摘要:

ANNUAL REPORTSON THEPROGRESS O F CHEMISTRYANNUAL REPORTSG. M. BENNETT, M.A., Ph.D.H. V. A. BRISCOE, D.Sc.H. M. DAWSON, D.Sc., Ph.D.F. G. DONNAN, C.B.E., LL.D., F.R.S.H. W. DUDLEY, O.B.E., Ph.D., F.R.S.A. C. G. EOERTON, M.A., F.R.S.W. E. GARNER, D.Sc., A.I.C.C. S. GIBSON, O.B.E., M.A., F.R.S.A. J. GREENAWAY, F.I.C.W. N. HAWORTH, D.Sc., F.R.S.I. M. HEILBRON, D.S.O., D.Sc., F.R.S.G. G. HENDERSON, M.A., D.Sc., F.R.S.J. T. HEWITT, D.Sc., F.R.S.C. N. HINSHELWOOD, M.A., F.R.S.ON THEC. K. INOOLD, D.Sc., F.R.S.J. KENYON, D.Sc.H. KING, D.Sc.W. H. MILLS, Sc.D., F.R.S.EMILE S. MOND.T. S. MOORE, M.A., B.Sc.J. R. PARTINGTON, M.B.E., D.Sc.E. K. RIDEAL, MA., D.Sc., F.R.S.R. ROBINSON, D.Sc., F.R.S.F. M. ROWE, D.Sc., F.I.C.J. L. SIMONSEN, D.Sc.S.SMILES, O.B.E., D.Sc., F.R.S.S. SUGDEN, D.Sc.PROGRESS OF CHEMISTRYW. T. ASTBURY, Ph.D.J. W. BAKER, D.Sc., Ph.D.H. BASSETT, D.Sc., Ph.D., D.+-Sc.G. M. BENNETT, M.A., Ph.D.J. D. BERNAL, M.A.E. J. BOWEN, M.A.B. A. ELLIS, M.A.E. H. FARMER, D.Sc.J. J. Fox, O.B.E., D.Sc.D. C. HENRY, M.A.F O R 1931.C. N. HINSHELWOOD, M.A., F.R.S.S. G. P. PLANT, M.A., D.Phil.A. G. POLLARD, B.Sc., A.I.C.J. PEYDE, M.Sc.E. K. RIDEAL, M.A., D.Sc., F.R.S.R. K. SCHOFIELD, M.A., Ph.D.N. V. SIDOWICK, O.B.E., M.A., Sc.D.,W. A. WOOSTER. Ph.D.F.R.S.ISSUED BY THE CHEMICAL s o c I m Y .6bitor :CLARENCE SMITE, D.Sc.VOl. XXVIII.L O N D O N :T H E C H E M I C A L S O C I E T Y1932PRINTED IN GREAT BRITAIN BYRICHARD CLAY & SONS, LIMITED,BUNQAY, IIUFFOLKCONTENTS.PAGEGENERAL AND PHYSICAL CHEMISTRY. By C.N. HINSHELWOOD,M.A., F.R.S. . . . . . . . . . . 13INORGANIC CHEMISTRY. By H. BASSETT, D.Sc., Ph.D., D.-2x3.-Sc. .ORGANIC CHEMISTRY :-Part ~.-ALIPHATIC DIVISION. By E. H. FARMER, D.Sc. . . .Part II.-HOMOCYCLIC DIVISION. By G. M. BENNETT, M.A., Ph.D.,and J. W. BAKER, D.Sc., Ph.D. . . . . . .Part III.-HETEROCYCLIC DIVISION. By S. G. P. PLANT, M.A., D.Phil.By J. J. Fbx, O.B.E., DSc., and B. A.ELLIS, M. A. . . . . . . . . . . ANALYTICAL CHEMISTRY.BIOCHEMISTRY.CRYSTALLOGRAPHY (1930-31).By A. G. POLLARD, B.Sc., A.I.C., and J. PRYDE, M.Sc.By J. D. BERNAL, M.A., and W. A.WOOSTER, Ph.D. . . . . . . . . .COLLOID CHEMISTRY. By W. T. ASTBURY, Ph.D., D. C. HENRY, M.A.,E. K.RIDEAL, M.A., D.Sc., F.R.S., and R. K. SCHOFIELD, M.A.,Ph.D. . . . . . . . . . . .4966105147179212262322THE STRUCTURE OF SIMPLE MOLECULES. By N. V. SIDGWICK,O.B.E., M.A., Sc.D., F.R.S., and E. J. BOWEN, M.A. . . . 36TABLE OF ABBREVIATIONS EMPLOYED IN THEAbbreviated Title.A. . . . . . .Acta Phytochim. . . .Amer. Inst. Met. Eng. Tech.Amer. J . Bot. . . .Amer. J . Pharm. . . .Amer. J . Sci. . . .Amer. Min. . . . .Anal. Asoc. Quim. ArgentinaAnal. Farm. Bioquim. .Anal. Fis. Quim., . .Analyst . . . . .Angew. Bot. . . . .Annalen . . . .Ann. Acad. Brasil. Sci. .Ann. Bot. . . . .Ann.Chim. . . . .Ann. Chim. analyt. . .Ann. Chim. Appl. . .Ann. Fdsif. . .Ann. Inst. Anal. Phys:Ann. Physik .. .Ann. Reports . . ,Ann. Sci. agron. franp. .Ann. Soc. Sci. Bruxelles .Pub.Chem.Apoth.-Ztg. . . . .Arch. Eisenhuttenw. . .Arch. Phurm. . . .Arch. Physique biol. . .Arch. Sci. phys. mt. . .Arhiv Hemiju . . .Arizona Agric. Exp. Sta.Arkiv Kemi, Min. Geol. .Atti 111 Cong. Naz. Chim.Atti R. Accad. Lincei . .Tech. Bull.Atti R. A d . Sci. Torino .Australian J . Exp. Biol.B. . . . . . .Ber. . . . . .Ber. deut. hot. G a . . .Ber. deut. physikal. Ges. .Biochem. J . . . . .Biochem. 2. . . . .Boll. chim.-farm. . . .Bot.Qaz. . . . .Brennstoff.-Chem. . .Brit. J . Exper. Path. . .Med. Sci.REFERENCES.FULL TITLE.Abstracts in Journal of the Chemical Society (until1925) or in British Chemical Abstracts,* SectionA.Acta Phytochimica.American Institute of Mining and MetallurgicalAmerican Journal of Botany.American Journal of Pharmacy.American Journal of Science.American Mineralogist.Anales de la Asociacih Quimica Argentina.Anales de Farmacia y Bioquimica (Buenos Aires).Anales de la Sociedad Espan6la Fhica y Quimica.The Analyst.Angewandte Botanik.Justus Liebig’s Annalen der Chemie.Annals da Academia Brttsileira de Sciencias.Annals of Botany.Annales de Chimie.Annales de Chimie analytique et de Chimie rtppliquhe.Annali di Chimica Applicata.Annales des Falsifications et des Fraudes.Annales de 1’Institut d’Analyse physico-chimique,Leningrad.Annalen der Physik.Annual Reports of the Chemical Society.Annales de la Science agronomique franpaise ete trang&re.Annales et Bulletin de la Soci6t6 royale des Sciencesmhdicales et naturelles de Bruxelles.Apo theker-Zeitung.Archiv fiir das Eisenhuttenwesen.Archiv der Pharmazie.Archives de Physique biologique.Archives des Sciences physiques et naturelles.Arhiv za Hemiju i Farmaciju.Arizona Agricultural Experimental Stations Tech-Arkiv for Kemi, Mineralogi och Geologi.Atti del 111” Congress0 nazionale di Chimica pura edapplicata (May, 1929).Atti (Rendiconti, Memorie) della Reale AccademiaNazionale dei Lincei, classe di scienze fisiche,matematiche e naturali, Roma.Atti della Reale Accademia delle Scienze di Torino.The Australian Journal of Experimental Biology andMedical Science.British Chemical Abstracts,* Section B.Berichte der deutschen chemischen Gesellschaft.Berichte der deutschen botanischen Gesellschaf t .Berichte der deutschen physikalisohen Gesellschaf t.The Biochemical Journal.Biochemische Zeitschrift.Bolletino chimico-farmaceutico.The Botanical Gazette.Brennstoff -Chemie.The British Journal of Experimental Pathology.Engineers Technical Publications.nical Bulletins.The y m is not inserted in references t o 193viii TABLE OW ABBREVIATIONS EMPLOYED IN THE REFERENCES.Abbreviated Title.Bul.Chim. SOC. RomdrGBul. SOC. Stiinte Cluj . .Bull. Acad. Polonaise . .Bull, Acad. roy. Belg. . .Bull. Acad. Sci. Roumaine .Stiin.Bull. Assoc. Chim. Sucr. .Bull. Chem. SOC. Japan .Bull. Sci. pharmacol. . .Bull. Soc. chim. . . .Bull. Soc.chim. Belg. . .Bull. Soc. Chim. biol. . .Bull. SOC. frang. Min. .Bull. Soc. Pharm. BordeauxBull. Torrey Bot. Club .Bull. Trav. Dep. Chim.Bull. Univ. Asie centrule .Bull. West Va. Univ. Sci.Inst. Hyg. $tat.Assoc.Bur. Stand. J . Res.Canadian J . Res.Cellulosechem. .Centr. Min. . .Chem. and lnd. .Chem. Erde . .Chem. Fabr. . .Chem. Listy . .Chem. News . .Chem. Obzor . .Chem. Reviews .Chem. Umschau .Chem. Weekblad .Chem. Zentr. .Chem.-Zta. . .Cdl. Czech. Chem. Comm. .Coll. Xymp. Ann. . .Coll. Symp. Monograph .Compt. rend. . . .Compt. rend. Soc. Biol. .Contr. Boyce ThompsonDamk Tidsskr. Farm. .Deut. Z. gerichtl. Med. .Ergeb. Agrik.-chem. . .Farm. Bhur, . . , .Inst.FULL TITLE.Buletinul de Chimie pur5 si applicatg SocietateaBuletinul Societiitii de Stiinte din Cluj.Bulletin Internationale de 1’AcadBmie Polonaise desSciences et des Lettres.Acad6mie royale de Be1gique.-Bulletin de la Classedes Sciences.Bulletin de la Section Scientifique de, 1’AcadBmieRoumaine.Bulletin de 1 ’Association des Chimistes de Sucrerieet de Distillerie et des Industries Agricoles deFrance et des Colonies.RomBn5 de Stiinte.Bulletin of the Chemical Society of Japan.Bulletin des Sciences pharmacologiques.Bulletin de la SociBt6 chimique de France.Bulletin de la SociBtB chimique de Belgique.Bulletin de la SocihtB de Chimie biologique.Bulletin de la SociBt6 frangaise de Min6ralogie.Bulletin des Travaux de la SociBtB de Pharmacie deBulletin of the Torrey Botanical Club.Bulletin des Travaux du DPpartement de Chimie deBulletin de l’Universit6 de 1’Asie centrale.Bulletin of the West Virginia University ScientificBureau of Standards Journal of Research.Canadian Journal of Research.Cellulosechemie.Zeitschrift fur Gerust-, Inkrusta-tions- und andere Begleitstoffe der Cellulose.Centralblatt fur Mineralogie, Geologie, und Palaon-tologie.Chemistry and Industry.Chemie der Erde.Die Chemische Fabrik.Chemick6 Listy pro VGdu a Pr8mysl. Organ de la“ CeskB chemickh SpoleEnost pro VEdu aPriimysl. ’ ’Chemical News.Chemickp Obzor.Chemical Reviews.Chemische Umschau auf dem Gebiete der Fette,Chemisch Weekblad.Chemisches Zentralblatt.Chemiker-Zeitung.Collection of Czechoslovak Chemical Communica-Colloid Symposium Annual.Colloid Symposium Monograph (now issued underComptes rendus hebdomadaires des SBances deComptes rendus hebdomadaires de SBances de laContributions from Boyce Thompson Institute.Dansk Tidsskrift for Farmaci.Deutsche Zeitschrift fur die gesammte gerichtlicheErgebnisse der Agrikulturchemie.Farmatxevtichnii Zhurnal.Bordeaux.1’Institut d’Hygi6ne d’fitat (Warsaw).Association.Oele, Wachse, und Harze.tions.foregoing title).l’Acad6mie des Sciences.SociBtB de Biology.MedizinTABLE OF ABBREVIATIONS EMPLOYED IN THE REFERENCES.ixAbbreviated Title.Fbrh. 111 Nord. . . .Fortschr. Min. . . . KemistmbtetCazzetta . . . .Helv. Chim. Acta . . .Illinois Agric. Exp. Sta.Ind.Chem. . . . .I d .Eng. Chem. .Ind. Eng. Chem. (Anai.)Indian J . Physics . .Iowa State Coll. J . Sci. ,J . . . . . . .J . Agric. Res. . . .J . Agric. Sci. . . .J . Amer. Ceramic SOC. .J . Amer. Chem. SOC. . .J . Amer. Phamn. Assoc. .J . Amer. Soc:Agrm. . .J . AppE. Chem. Russia .J . Assoc. Off. Agric. Chem.J . Biochem. Japan . .J . Biol. Chem. . . .J . Chem. I d . Russia . .J . Chim. physique . .J . Counc. Sci. Ind. Res.J . Dept. Agric. S. AustraliaTech. Bull.AustraliaJ . Econ. E n t m . . .J . Exp. Agron. RussiaJ . Exp. Med.J . Fm. Agric. HoikaiioJ . Franklin Inst. . .J . Gen. Chem. Russia .J . @en. Physiol. . .J . Ind. Eng. Chem. .J . Indian Chem. SOC. .J . Indian Inst. Sci. .J . Inst. Metals . .J . Iron Steel Inst. .J .Landw. . .harm. Big. . .J . Phamn. Chim. . .J . Pharm. Soc. JapanJ . Phys. Radium . .J . Physical Chem. .J . Physid. . . .J.pr.Chem., . .J . Rms. Phgs. Chem. Soc. .J . Sci. Inst. , . .J . Soc. Chem. I d : . .J . Soc. Chem. Ind. Japan .J . SOC. Dyers Col. . .FULL TITLE.Nordiska Kemistmotet Forhandlingar och Foredrag,Fortschritte der Mineralogie, Kristallographie undGazzetta chimica italiana.Helvetica Chimica Acta.Illinois Agricultural Experimental Stations TechnicalThe Industrial Chemist and Chemical Manufacturer.Industrial and Engineering Chemistry.Industrial and Engineering Chemistry : AnalyticalIndian Journal of Physics.Iowa State College Journal of Science.Journal of the Chemical Society.Journal of Agricultural Research.The Journal of Agricultural Science.Journal of the American Ceramic Society.Journal of the American Chemical Society.Journal of the American Pharmaceutical Association.Journal of the American Society of Agronomy.Zhurnal prikladnoi Chimii.Journal of the Association of Official AgriculturalJournal of Biochemistry (Japan).Journal of Biological Chemistry.Journal of Chemical Industry of Russia.Journal de Chimie physique.Journal of the Council for Scientific and IndustrialJournal of the Department of Agriculture of SouthJournal of Economic Entomology.Journal of Experimental Agronomy, Russia.Journal of Experimental Medicine.Journal of the Faculty of Agriculture, HokkaidoImperial University.Journal of the Franklin Institute.Journal of General Chemistry (Russia).Journal of General Physiology.Journal of Industrial and Engineering Chemistry(now Industrial and Engineering Chemistry).Quarterly Journal of the Indian Chemical Society.Journal of the Indian Institute of Science.Journal of the Institute of Metals.Journal of the lron and Steel Institute.Journal fiir Landwirtschaft.Journal de Pharmacie de Belgique.Journal de Pharmacie et de Chimie.Journal of the Pharmaceutical Society of Japan(Yakugakuzasshi).Journal de Physique et le Radium.Journal of Physical Chemistry.The Journal of Physiology.Journal fur praktische Chemie.Journal of the Physical and Chemical Society ofJournal of Scientific Instruments.Journal of the Society of Chemical Industry.Journal of the Society of Chemical Industry, JapanJournal of the Society of Dyers and Colourists.A 23rd Meeting, Helsingfors.Petrographie.Bulletins.Edition.Chemists.Research (Australia).Australia.Russia.(K6gy6 Kwagaku Zasshi)X TABLE OF ABBREVIATIONS EMPLOYED IN T€IE REFERENCES.Abbreviuted Title.J .Soc. Glass. Tech.J . SOC. Leather T;ades"J . Text. Inst. . . .J . Text. Sci. . . . .Jahrb. kgl. preuss. geolog.Landesanst . Bergakad.Jahrb. Min., Bei1.-Bd. .Jahrb. wiss. Bot. . . .K. 8venska VetenskapsKolloidchem. Beih. . .Kolloid-Z. . . . .Lancet . . . . .,Landbouw. (Java) . .Landw. Jahrb. . . .Latvij. Univ. Raksti . .Magyar Chem. Fol. . .Magyar Gy6. T h u s . $rt. .Mem. Coll. Sci. Kyoto .Mem. Dept. Agric.India .Mem. Nanchester Phil. Soc.Mkm. Poudres . . .Mem. Ryojun Coll. Eng. .Met. and Alloys . . .MetalInd. . . . .MetaElu.Erz . . .Metallwirt. . . . .Mikrochem. . . . .Min. Mag. . . . .Missouri Exp. Sta. Res.Mitt . deut . Materid- prii f.Mitt. Kaiser- Wilh. Inst.Nitt. kgl. bayr. Moorkultur-Mitt. Lebensm. Hyg. . .Monatsh. . . . .N . Carolina Agric. Exp.Nach. Ges. IViss. G6ttingen.Nut. Centr. Univ. Sci. Rep.Naturwiss. . . . .Natuurwetensch. Tijds. .New Humps. Agric. Exp.Sta. Bull. . . . .Nippon Kogyokwaishi .Chem.Akad. H a d .Bull.Berlin-DahlemEisen forsch.anstaltSta. Tech. Bull.Neft. Khoz. . . .FULL TITLE.Journal of the Society of Glass Technology.Journal of the International Society of LeatherTrades' Chemists.The Journal of the Textile Institute.Journal of Textile Science.Jahrbuch der koniglichen preussischen geologischenLandesanstalt und Bergakademie.Neues Jahrbuch fiir Mineralogie, Geologie undPaltiontologie, Beilage-Band.Jahrbucher fiir wissenschaftliche Botanik.Kongliga Svenska Vetenskaps Akademiens Hand-lingar.Kolloidchemische Beihefte.Kolloid-Zeitschrift .The Lancet.Landbouwkundige Serie (Proefstation voor de JavaLandwirtschaftliche Jahrbucher.Lat vi j as Universit Ltes Raks t i .Magyar Chemiai Foly6irat (Hungarian ChemicalMagyar Gy6gyszerBsztudomhnyi TArsasBg lhtesitoje.Memoirs of the College of Science, Kyoto ImperialMemoirs of the Department of Agriculture in India.Memoirs and Proceedings of the Manchester LiteraryMBmorial des Poudres.Memoirs of the Ryojun College of Engineering.Metals and Alloys.The Metal Industry (London).Metal1 und Erz.Me tallwirtschaft, Metallwissenschaf t , Metalltechnjk.Mikro chemie .Mineralogical Magazine and Journal of the Minera-Missouri Experimental Stations Research Bulletins.Mitteilungen der deutschen Materialpriifungsan-Mitteilungen DUS dem Ksiser-Wilhelm Institut fiirMitteilungen der koniglichen baeyerischen Moor-Mitteilungen &us dem Gebiete der Lebensmittelunter-Xonatshefte fiir Chemie und verwandte TheileNorth Carolina Agricultural Experimental StationsNachrichten von der Gesellschaft der WissenschaftenNational Central University (Nanking) ScienceDie Naturwissenschaften.Natuurwetenschappelijk Tijdschrift.Neftyanoe Khozyaistvo (Petroleum Industry).New Hampshire Agricultural Experimental StationsNippon Kwagaku Kwaishi (Journal of the ChemicalSuikerindustrie).Journal).University.and Philosophical Society.logical Society.stalten.Eisenforschung zu Dusseldorf.kulturans talt .suchung und Hygiene.anderer Wissenschaften.Technical Bulletins.zu Gottingen.Reports.Bulletins.Societv of Janan).Norsk Geol.Tidsskr. . . Norsk Geoiogisk fidsakriftAbbreviated Title.Norsk Videnskabsselskab. .Nova Acta (Upsala) .NuovoCim. . . . .Oesterr. bot. 2. . . .Oesterr. Chem.-Ztg. . .Ohio Agric. Bxp. Eta. Bull.PJEanzenbau . . . .Pharm. J . . . .Pharm. Weelcblad . .Pharm. Zentr. . . .Phil. Bag. . . . . Pharm.-Ztg.. . . .Phil. Trans. . . . .Phot. J . . . . .Physicd Rev. . . .Physikal. 2. . . . .Phytopath. . . .Plant Physioi. . . .Planta . . . . .Forstwirts.Proc. Acad. Sci. AmsterdumTABLE OF ABBREVIATIONS EMPLOYED IN 9%CE REFERENCES. X iPoln. Jahrb. Land- u. Polish Agricultural and Forestal Annual.Proc. Amer. Acad. . .Proc. Assoc. SouthernProc. Imp. Acad. TokyoProc. K. Akad. . Wetensch:Proc. Nut. Acad. Sci. . .Proc. Nova Scotian Inst. Sci.Proc. Physical Soc. . .Proc. Roy.Soc. . . .Proc. Roy. SOC. Edin. . .Proc. SOC. Exp. Biol. Med.Protoplmmcb. . . .PrzemystChem. . . .Quart. J . Pharm.. . .Rec. trav. chim. . . .Agric. WorkersAmsterdamRev. brad. Chim. . .Rev. Chim. pura appl. .Rev. Fac. Cienc. quim. LaRev. gin. Colloid.. . .Rhode I. Agric. Exp. Sta.Rocz.Chem.. . . .PlataBull.Schweiz. me&. Woch.Bci. Papers Inst. Ph&Chem. Res. TokyoBci. Rep. TGhoku Imp. Univ.Sewnamdd. . . .FULL TITLE.Skrifter udg. af Videnskabsselskabet i Oslo.Nova Acta Regiae Societatis Scientiarum Upsaliensis.I1 Nuovo Cimento.Oest,erreichische botanische Zeitschrift.Oesterreichische Chemiker-Zeitung.Ohio Agricultural Experimental Station Bulletins.Wissenscheftliches Archiv fiir Landwirtschaft. Ab-teilung A. Pflanzenbau.Pharmaceutical Journal.Pharmaceutisch Weekblad.Pharmazeutische Zentralhalle.Pharmazeutische Zeitung.Philosophical Magazine (The London, Edinburgh andDublin).Philosophical Transactions of the Royal Society ofLondon.The Photographical Journal.Physical Review.Physikalishhe Zeitschrif t .Phytopathology.Plant Physiology.Zeitschrift fiir wissenschaftliche Biologie.AbteilungE. Planta. Archiv ~ wissenschaftliche Botanik.Proceedings of the Royal Academy of Sciences ofProceedings of the American .Academy of Arts andProceedings of the Association of Southern Agri-Proceedings of the Imperial Academy of Japan.Koninklij ke Akademie van Wetenschsppen te Am-Proceedings of the National Academy of Sciences.Proceedings of the Nova Scotian Institute ofProceedings of the Physical Society of London.Proceedings of the Royal Society.Proceedings of the Royal Society of Edinburgh.Proceedings of the Society for Experimental Biologyand Medicine.Internationale Zeitschrift fiir physikalische Chemiedes Pro toplasten.Przemysi Chemiczny.Quarterly Journal of Pharmacy and Pharmacology.Recueil des t.ravaux chimiques des Pays-Bas et dela Belgique.Revista brasileira de Chimica.Revista de Chimica pura e applicata.Revista de la Facultad de Ciencias quimicas (Univer-sidad nacional de La Plata).Revue gkkrale des Colloides.Rhode Island Agricultural Experimental StstiozlsBulletins.Roczniki Chemji organ Polskiego TowarzystwaChemicznego .Schweizerische medizinische Wochenschrift.Scientific Papers of the Institute of Physical andChemical Research, Tokyo.Scientific Reports, TBhoku Imperial University.La Semana m6dica (Buenos Aires).Amsterdam (English Version).Sciences.cultural Workers.sterdam.Sciencexii TABLE OF ABBREVIATIONS EMPLOYED IN THE REFERENCES.Abbreviated Title.Sitzungsber .H eidel bergerSitzungsber. Preuss. Akad.Soil Sci. . . . .Akad. Wiss.Wiss. BerlinSprechsaal . . * .Stahl u. Eisen . . .State Inst. Tobacco Invest.S u m e n Kem. . . .Svensk Kem. Tidskr. . .Tech. Rep. TGhoku . .Tidsskr. Kjemi Berg. . .Trans. Ceramic SOC. . .Trans. Faraduy doc. . .Trans. Inst. Pure Chem.Trans. Roy. SOC. Canada .Trans. Sci. Inst. Fert. .Bull. ( U.S.S.R.)Reag.Trans. State Inst. Test.Building Hat. . . .Tsch. min. petr. diitt. .Tzvet. Met. . . .U U r . ~ r o z i a i . . .Ukraine Chem. J . . .U.S. Dept. of Agric. . .U.S. Public Health Rep. .Univ. of Calif. Expt. Sta. ofColl. of Agric.Univ. Toronto StudiesGeologyVerhandl.I I K m m . Intern.Bodenkunde Gesell.BudapestWelsh J . Agric. .2. a d . Chem. .Z. angew Chem. .2. anorg. Chem. .Z . Elektrochem. .2. Krist. . .2. M e a l k . . .Z . Parasitenk. .2. PJlanz. Dung. .2. Physik . .2. physikal. Chem.Z. physiol. Chem.8. tech. Physik. .2. Unters. Lebensm.2. wiss. Mikr. .2. wiss. Phot. .ZemeRt . . .FULL TITLE.Sitzungsberichte der Heidelberger Akademie derSitzungsberichte der Preussischen Akademie derSoil Science.Sprechsaal fur Keramik, Glas und verwandte Indus-trien Fach- und Wirtschaftsblatt.Stahl und Eisen.State Institute for Tobacco Investigations.Suomen Kemistilehte (Acta Chemica Fennica).Svensk Kemisk Tidskrift.The Technology Reports of the TBhoku ImperialTidsskrift for Kjemi og Bergvaesen.Transactions of the Ceramic Society.Transactions of the Faraday Society.Transaction9 of the Institute of Pure ChemicalTransactions of the Royal Society of Canada.Transactions of the Scientific Institute of FertilisersTransactions of the State Institute for Testing Build-Tschermaks mineralogische und petrographischeTzvetnine Metallni (Non-ferrous Metals).Udobrenie i Urozhai (Fertilisers and Crops).Ukraine Chemical Journal.United States Department of Agriculture.United States Public Health Service : Public HealthReports.University of California, Experimental Station of theCollege of Agriculture.University of Toronto Studies : Geological Series.International Society of Soil Science (German Ver-The Welsh Journal of Agriculture.Zeitschrift ftir analytische Chemie.Zeitschrift fur angewandte Chemie.Zeitschrift fur anorganische und allgemeine Chemie.Zeitschrift fur Elektrochemie (und angewandtephysikalische Chemie).Zeitschrift fur Kristallographie.Zeitsc hrif t fur Me tall kunde.Zeitschrift fur Parasitenkunde (Abteilung F.Zeit-schrift fur wissenschaftliche Biologie).Zeitschrift fur Pflanzenernahrung und Dungung.Zeitschrift fur Physik.Zeitschrift fur physikalische Chemie, StochiometrieHoppe-Seyler's Zeitschrift fiir physiologische Chemie.Zeitschrift fur technische Physik.Zeitschrift fur Untersuchung der Lebensmittel.Zeitschrift fur wissenschaftliche Mikroskopie undZeitschrift fiir wissenschaftliche Photographie,Zement (Wochenschrift fur Hoch- und Tiefbau).Wissenschaften.Wissenschaften zu Berlin.University.Reagents (Moscow).(Moscow).ing Materials and Glass.Mi tteilungen.sion of Proceedings at 2nd Meeting).und Verwandt schaf t slehre.fiir mikroskopische Technik.Photophysik und Photochemie

ISSN:0365-6217    

DOI:10.1039/AR9312800001

出版商:RSC    

年代:1931

数据来源: RSC

摘要:

ANNUAL REPORTSON THEPROGRESS OF CHEMISTRY.GENERAL AND PHYSICAL CHEMISTRY..MUCH of the work published during the past year has been devotedto extending or consolidating advances to which reference has alreadybeen made in these Reports. This circumstance has not renderedany easier than usual the selection of matters to be discussed. Thefollowing pages, therefore, can in no sense claim to be complete : a tbest it may be hoped that they will provide a more or less representa-tive sample of the kind of investigation which has been going on. Inthe newer quantum theory no fundamental advances have been made,but there have been several important applications to problems ofchemistry. The interest of these applications is so great that thepossibility of simplifying the mathematical technique of quantummechanics, even with some sacrifice of formal accuracy, is one whichshould be very well worth exploring.Definite advances are being made in solving the problem of thestructure of the atomic nucleus, but so far there is not even theglimmering of a theory about the forces which hold the nucleustogether.There has been much valuable systematic work in connexion withthe theory of solutions, crystal structure, and especially the elucid-ation of molecular structure with the aid of measurements of dipolemoments and of the Raman effect.In the field of chemicalkinetics there has also been considerable activity.Atoms, Electrons, and Protons.Much work has been published dealing with the theoreticalimplications of the quantum mechanics.The success of this ingiving a quantitative account of a very large variety of physicalphenomena is more and more demonstrated: but the feeling isalso growing that something more fundamental than the formalismof this calculus is desirable, and that there may, for example, besomething to be said for re-introducing phase relationships in dealin14 HINSHELWOODwith atomic interactions,l instead of treating the matter entirely interms of the rather difficultly understandable exchange energy. Butthe time is hardly ripe for the discussion of this in these Reports.There have been several more detailed discussions of the theory ofmolecular forces,2 including interesting attempts to draw con-clusions about molecular structure (see following section) .3 Anotherdevelopment of interest to chemists is the discussion from thequantum mechanical point of view of collision processes and the con-ditions governing the interchange of energy which may occur duringthem. C.Zener,* for example, considers the collision between anatom and a diatomic molecule : it appears that in simple systems theprobability of an interchange of vibrational energy is quite a smallone. Ionic and electronic collisions have also been considered by anumber of authors. The variation of effective atomic cross sectionfor various types of electronic collision is discussed by H. S. W.Massey and C. B. 0. Mohr.5 I n a general way it appears that thecomplex experimental relationships can be accounted for.Experimental work on the diffraction of electrons has continued.6P.M. S. Blackett and F. C. Champion have studied the scatteringof slow a-particles by helium and confirmed Mott’s theory of theprocess, which yields results differing from classical theory.The most interesting development in the whole field is probablythe experimental one due to Rutherford and his school, which carriesus a step further in the understanding of the nature of the atomicnucleus. For the last year or two interest has been rather centredon the quantum mechanical theory of nuclear disintegration, whichgives in general terms a roughly quantitative description of thephenomena of a-particle emission, but, from its nature, does not tellmuch about the structure of the nucleus or the “mechanism” ofdisintegration.The success of the new investigation depends upona method for counting a-particles accurately : * the small ionisationcurrent caused by the particle traversing a few millimetres of its1 Compare R. M. Langer, BuffaIo Meeting of Amer. Chem. SOC., Sept. 1931.2 W. Heitler and G. Rumer, 2. Physik, 1931, 68, 12; A., 547; R. de L.Kronig and W. G. Penney, Proc. Roy. SOC., 1931, [ A ] , 130, 499; A., 407; M.Delbruck, ibid., 1930, [ A ] , 129, 686; A., 17; J. E. Lennard-Jones, ibid., p .538; A., 17; F. Hund, 2. Physik, 1931, 73, 1.3 L. Pauling, J . Amer. Chem. SOC., 1931, 53, 1367; A., 670.Physical Rev., 1931, 37, 556; A,, 543.Proc. Roy. SOC., 1931, [A 1,132, 605.F. L. Arnot, ibid., 1931, [ A ] , 130, 655; A., 542; R.Wierl, Ann. Physik,Proc. Roy. SOC., 1931, [ A ] , 130, 380; A., 280.1931, 8, 521 ; A., 665.* (Sir) E. Rutherford, F. A. B. Ward, and C. E. Wynn-Williams, ibid.,1930, [A], 129,211 ; A., 1930,1338; C. E. Wynn-Williams and F. A. B. Ward,ibid., 1931, [A], 131, 391 ; A., 666GENERAL AND PHYSICAL CHEMISTRY. 15path is amplified by means of a valve. The corresponding ionisationproduced by a p-particle is too small to be recorded. By suitablearrangement of the amplifying and recording system it is possible tocount a-particles even in presence of a strong y-radiation. Adifferential method was then developed which allowed the countingof those particles having ranges between say x and x plus a fewmillimetres, instead of as usual the total number with rangesexceeding a given amount.This was rendered possible by the useof a double ionisation chamber of special construction : the numberstopping within a region about 2 mm. broad could be detected andcounted. With the new counter it was possible to detect the missingshort-range or-particles from the dual disintegration of radium-C-those corresponding to the C" branch.Since 1919 it has been known that radium-C, in addition to thenormal 7-cm. range particles, gave rise to a group of long-rangeparticles. Analysis of these by the new method reveals the factthat they can be resolved into a t least 9 homogeneous groups between7 cm. and 12 cm. range, the ranges and relative numbers in eachgroup being determined. Prom the ranges the velocities and energiescan be estimated by the usual methods.The existence of these long-range groups is now correlated with the emission of y-rays in aremarkable manner.The general theoretical picture is as follows. Radium-C emits a@-particle giving rise to radium0 : some of the a-particles in thenew nucleus are in excited levels, from which they either escape aslong-range particles, or fall to a lower level with emission of a y-ray.It is from the ground level of the radium-C' nucleus that the normal7-cm. range particles are supposed to come. (In certain cases theremay be emitted instead of the y-ray itself a @-particle liberated fromthe outer atom by some process of internal conversion.)l* The firstpoint which emerges is that the maximum energy which could bereleased in a transition from a level corresponding to the particles ofhighest energy to the ground level is about equal to the maximumenergy of any @-ray line in the magnetic spectrum of radium-C (theselines come largely from the conversion of y-rays).From the energies of the fast a-particles a series of energy levelsabove the normal level can be calculated.Assumed transitionsbetween these or from them to the ground level can then be comparedwith the energies of y-rays or the corresponding p-rays of the magneticspectrum. The intensity of the y-rays is of the order of one quantum(Lord) Rutherford, F. A. B. Ward,and W. B. Lewis,Proc. Roy. SOC., 1931,lo Compare R. H. Fowler, ibid., 1930, [A], 129, 1; A., 1930, 1338; C.D.[A], 131,684; A., 890.Ellis and G. H. Aston, ibid., p. 180; d., 1930, 133916 HTNSHELWOOD :for each two or three disintegrations, but the number of nuclei whichdisintegrate to give the fast particles is of the order of 1-10 in amillion, so that the probability of a change in energy level withemission of radiation is very much greater than that of the escape ofone of the “excited” a-particles. The energy differences of thea-particle states are not only of the same order of magnitude as they-ray energies, but in several examples numerical agreement wasfound, lending still stronger support to the idea that the quantum ofy-radiation is emitted during an a-particle transition in an excitednucleus.Working on this basis, Lord Rutherford and C.D. Ellis l1 analysethe numerous y-rays from radium-C‘ into an orderly scheme. Twokinds of energy-level system are theoretically possible. In the first,a given particle could occupy a series of energy levels of differentquantum numbers, in a manner analogous to the successive electronicstates of the hydrogen atom. In the second, the different levels aredue to the excitation of varying numbers of particles to the samehigher state. The Pauli principle rules out this second class ofsystem for electronic states, but permits it in the case of a-particles.Rutherford and Ellis take as their working hypothesis the simpleassumption that transitions occur whereby the number of particlesin a single excited state changes in one act from r to r’ withemission of a quantum of radiation.If E~ and c2 are the energies ofeach of the particles in the ground state and the excited state beforethe transition, and E,‘ and E ~ ‘ the corresponding quantities after thetransition, then, if n is the total number of particles, the totalenergies before and after the transition are given respectively by(n - r ) ~ ~ + m2 and by (n - r ’ ) ~ ~ ’ + TIEZ’ ( E ~ ’ and E ~ ’ are changedbecause there is necessarily a mutual action of the a-particles). Theseconsiderations indicate that the energies of the y-rays should berepresentable in the form hv = p E , - qEz, where p and q areintegers. The experimental data are found to be compatible withsuch a scheme, though it is not excluded that slightly differentschemes might fit the facts equally well.R.H. Fowler,12 considering the quantum mechanical aspect ofthe problem in the light of these new results, finds by the analysis ofa very rough and ready model, vk., a one-dimensional model in whicha-particles act on one another with potential energies of a quadraticform, that the energy levels are such as to give rise to y-rays offrequencies represented by an expression of the form hv = p ( E , -qE,). The necessary modification of the formula of Rutherford andEllis would not do violence to the experimental facts.11 Compare R. H. Fowler, Proc. Roy. Soc., 1031, [A], 132, 667.12 Nature, 1931, 128, 453GENERAL AND PHYSICAL CHEMISTRY. 17Physical Theory and Benzene Structure.In the last Report reference was made to the work of E.Huckel onthe quantum mechanical interpretation of the " rigidity " of chemicaldouble bonds. The simpler structural problems of organic chemistryare so beautifully and completely treated with the aid of the tradi-tional ideas that the translation of these ideas into the language ofwave mechanics must be regarded rather as a satisfaction to thephysicist than as a real advance in chemistry. But there arecertain problems which the ordinary conceptions of chemistry havenot been able to solve without the aid of auxiliary ideas sometimes ofa rather indefinite character. Prominent among these problems arethe questions of the structure of aromatic compounds and theorientation of substituents in the benzene nucleus. Here especiallythe introduction of new guiding principles is particularly valuable,and we may well look with interest to see whether a quantummechanical treatment does indeed go a step beyond re-interpretingwell-tried old ones.It must be remarked at the outset that any-thing like a complete quantum mechanical analysis, starting fromfirst principles, of a problem so complex as the structure of benzeneis impossible. Even the treatment of the hydrogen molecule has tobe based upon approximations, which already take for grantedcertain empirically established facts. For example, as F. Hundpoints when Heitler and London neglected the Coulomb forcesbetween two hydrogen atoms in comparison with the " exchangeforce" they were virtually taking advantage of the empiricalinformation that the inert gases have in fact no chemical affinity.Indealing with benzene, therefore, Huckel l4 has to begin by makingvarious assumptions the validity of which cannot be estimatedexcept by reference to the results. Nevertheless, certain discoveriesemerge which appear to be of great importance.The method of analysis is based upon the fact that in benzene thereare six bonds over and above those engaged in the single linkagesof carbon to carbon or carbon to hydrogen. Thus there are sixelectrons not accommodated in ordinary non-polar single bonds(each carbon brings four outer electrons, each hydrogen one : total30. Huckel takes themore general case of n CH groups in a ring and n electrons, and triestwo methods of approximation.In the first, each electron is thoughtof as assigned to one ring atom in a definite quantum state, and theinteraction between them is investigated by methods analogous tothose which have been successfully applied to the determination ofinteraction in many-electron systems in connexion with ferro-magnetic phenomena. It transpires that rings with an odd numberlS 2. Phyeik, 1931, 73, 1. l4 Ibid., 1931, 70, 204.The 12 single bonds require 24, leaving 6)18 HINSHELWOOD :of carbon atoms should possess a greater energy content thanthose with an even number, but there appears to be no other resultof obvious chemical interest. The second method of approximationneglects at first the “ exchange energies ” of the electrons, andconsiders the n electrons in a field of force which varies periodicallyround the ring.The possible quantum states of these electrons areworked out, and the important result appears that, when the Pauliprinciple is introduced (Le., that only two electrons of opposite spinscan occupy the same quantum state), systems of electrons of 2, 2 +4 = 6, 2 + 4 + 4 = 10 are found to constitute “ closed groups,”somewhat analogous to the closed groups in the atoms of the periodicsystem. Since C2H2 is not a ring and C,,H,, is not known at all, thesix-electron system occupies a unique place, and the stability of theclosed group is evidently responsible for some of the characteristicproperties of benzene and the aromatic compounds. The 8-group isnot a closed one, which may well explain the well-known lack ofaromatic character shown by cyclooctatetraene.Heterocyclic six-membered rings such as pyridine, or five-membered rings such asthiophen, in which the heterocyclic atom can contribute more thanone electron can also show aromatic properties. Although the effectof the disturbed cyclic symmetry on the behaviour of the electronsin these examples cannot be calculated, it is not ah all unreasonablet o suppose that the importance of the closed groups of six persists.To sum up, we may say that while quantum mechanics cannot solvethe benzene problem in anything like a complete way, it shows thatthere is good ground for believing that ring systems in which a groupof six electrons unaccommodated in single bonds occurs will possessspecial properties and probably unusual stability.This appears tobe a result of great importance.Huckel has also dealt with the problem of benzene substitution,lsmaking approximate estimates of the disturbance of charge distribu-tion of the electrons caused by the presence of a substituent. Accord-ing t o his arguments, the negative charge in, for example, nitro-benzene is increased relative to benzene in the ortho- and para-positions and reduced in the meta-position, Le., in this example theelectrons are “ repelled from the carbon atom where the substitutionhas taken place and from themeta-carbon atom towards theortho- andpara-atoms.” This is an effect of the opposite sign from that postu-lated by the simple theory of “ alternating polarities,” but accordingto Huckel a carbon atom where there is a defect of negative chargewill repel a hydrogen nucleus, thereby lessening the work which mustbe done in removing it.Substitution thus becomes easier. Meta-substitution occurs therefore in the nitrobenzene example.lo 2. Phyeik, 1931, 72, 310GENERAL AND PHYSICAL CHEMISTRY. 19It should be mentioned in this connexion that L. E. Sutton 16 hasshown by direct comparison of the dipole moments of correspondingaromatic and aliphatic compounds that " electron drifts " away fromor towards the substituent group can in fact be detected. This isimportant, since for the first time it establishes the physical reality ofthe electrical changes which various current theories of organicreactions postulate.The conception of the " electronic cloud " which Schrodinger'stheory introduces has hitherto proved useful in forming a picture ofseveral phenomena : e.g., the interaction of the clouds was used byHuckel in interpreting the properties of the double bond, and histheory of induced polarities deals with disturbances of the electricdensity associated with the 6 '' ring " electrons of benzene.In a stillsimpler'example repelling or attracting hydrogen atoms with the aidof an unequal density distribution can be pictured thus :-It seems possible that an interpretation of some of the mostimportant quantum mechanical results relating to molecular forcescould be worked out, which would enable chemists to solve theirparticular problems with the aid of rules determining the behaviourof electron clouds.These rules would be simple and approximate andutilisable in their proper sphere in much the same waty as that inwhich Faraday used the lines of force, or van 't Hoff the rigid directedbond. It is to be hoped that the possibility of constructing somesuch theory will be investigated.Potential-energy Curves and their Applications.For the interpretation of the physical and chemical behaviour ofdiatomic molecules consideration of the potential-energy curve isoften of great help. This curve (Fig. 1) represents the potentialenergy of the molecule as a function of the distance between theatoms, and has the form shown in the figure. At the point wherer = r,, the energy is a minimum and the molecule is in its normalequilibrium state.When it is vibrating the atoms may be atl6 Proc. Roy. SOC., 1931, [A], 133, 66820 HINSHELWOOD :distances greater or smaller than ro. For the smaller separations theenergy increases very rapidly towards indefinitely great values, sincethe compressibility of a molecule is very limited. As the separationof the atoms exceeds the equilibrium value the energy increases atfirst fairly rapidly and in approximate accordance with the law ofa, simple harmonic oscillator, and then more slowly as the bindingforces between the atoms get weaker and weaker. Finally theenergy reaches a constant limiting value corresponding to completedissociation of the molecule. The distance D in the figure representsFIQ.1.the energy of dissociation. An exact theoretical equation for theform of this curve is hardly possible to obtain, since it will dependupon the variation of binding force with distance, but various semi-empirical equations are used, the constants in which can be evaluatedby the aid of data obtained from band spectroscopy. One of themost convenient of these equations is that of P. M. Morse 1' whichwill be briefly explained, since it is likely to become of increasingimportance in chemical calculations.The energy of the molecule is represented by the expression2De - - t o ) - - 2a(r - r,,) E(r) = Del7 Ph.ysical Rev., 1929, 34, 57; A., 1929, 975GENERAL AND PHYSICAL CHEMISTRY. 21E(r) is the energy for a displacement r of the two atoms, D is thedissociation energy, and a is a constant.This expression possesses the following properties : as r approaches00, E comes asymptotically to the value zero, i.e., the energy of thecompletely separated atoms is taken as the standard level; E has asingle minimum of - D a t r = r o ; when r = 0 the value of E ,although not infinite as it should be, is very great, which is a goodenough approximation.Thus the general shape of the curve isprovided for. The equation has a further important property : ifwe write down Schrodinger’s wave equation for an oscillator andsubstitute the above value for the potential energy and then deter-mine the allowed values for the various energy levels of the vibratingsystem, we obtain a series of the same form as one of the best ofthe empirical spectroscopic equations.The constants of the twoexpressions can be equated, and thus a can be expressed in terms ofspectroscopic data. For the nth level Morse’s equation gives W(n) =hao(% + 4) - (h2aO2/4D)(n + +)2. The spectroscopic vibrationallevels can be well expressed by the formula W(n) = hwo[(n + 8)- x(n + +)2] : wo is the frequency of oscillations small enough tobe simple harmonic ; from the original equation it is easily found tobe equal to - - , where p is the ‘c reduced mass.” Afterequation of constants and simplification, the value finally found fora is 0-2454(&fo0x)t, where M = MIM,/(M1 + M,), M , and M ,being the atomic weights of the two nuclei on the oxygen scale andwo being expressed in wave numbers.Morse also gives an empiricalrule for finding ro, wiz., riao = 3000 A.3/cm. : the latter, however,is not regarded as of universal validity.Among the applications of the potential-energy curve, we mayfirst consider the approximate estimation of the energies of activationof chemical reactions. Reference was made in the last Report l8 tothe calculations of Villars. The idea underlying these has beenextended and modified by Eyring and Polanyi, in a series of veryinteresting calculations based on the London theory of valency andof intermolecular forces.lg The force between two atoms is made upof two parts : an electrostatic part called the Coulomb force, and aforce depending on the quantum mechanical phenomenon ofresonance,20 and going by the name of the “exchange force.” Invery simple examples the magnitude of these forces can be estimated.In molecule formation the exchange force is the more important.In2x TD>f PAnn. Reports, 1930, 27, 19.l9 H. Eyring and M. Polanyi, 2. physikal. Chem., 1931, [B], 12, 279; A.,Zo Ann,. Reports, 1930, 27, 24.688; H. Egring, J . Amer. Chsrn. SOC., 1931, 53, 2637; A., 114022 HINSHELWOOD :calculating an energy of activation we must be able to estimate theforces acting between a number of atoms present together: e.g.,between three atoms when we are considering a reaction of the typeY + XZ = YX + Z ; or between four atoms in a reaction of thetype WX + YZ = WZ + XY. As we have just seen, informationabout the energy of diatomic combinations can be derived from theband spectra of the diatomic molecule ; the next step is renderedpossible by some formulze of London’s which give the total energy ofa system of three or four atoms in terms of the energies which theseatoms would possesss if they existed as isolated pairs (diatomicmolecules) with nuclear separations equal to their actual distancesapart in the polyatomic codiguration. For three atoms the totalenergy is given bywhere Q = A + B + C, the sum of the three Coulomb energies ofthe three atoms taken in pairs, and a, 8, and y are the exchangeenergies of the three possible isolated molecules. For four atomsthe expression becomesE = Q + [${(a - P)’ + (a - yI2 + (P - y)’P= Q + “a1 + a2 - 81 - PJ2 + (a1 + a2 - y1 - yJ2 +(P1 + P2 - y1 - y2)2)lfwhere Q is the sum of six Coulomb energies, and al, a2, .. . , etc.,are the exchange energies of the six diatomic combinations. Toproceed further some rather bold approximations are necessary.The total energies of the diatomic combinations are first obtainedfrom the band spectra of the corresponding molecules. A roughestimate, based upon the analogy of very simple cases such as H2where actual calculation is possible, is then made of the proportionof the total energy which is Coulomb energy and the proportion whichis exchange energy : thus the separate terms of the above formulze arefound. To assume that the proportion is constant for differentdistances of the atoms is obviously a rough and ready procedure, butis more or less justified by the fact that the Coulomb energy is ingeneral only a small fraction of the total. We now can calculatein principle the total energy of any configuration of three or fouratoms and can thus study its variation as one molecule approachesanother from a great distance and comes into chemical reaction withit. If we startwith XZ at the normal molecular distance, and Y far removed, andthen bring up Y, the energy increases : it passes through a maximumand can then fall again if, for example, Z is removed to infinityleaving the molecule YX behind.The “ reaction ” which hasoccurred has involved passage over an “energy pass.” The minimumheight which can be found for this pass for any separation andThe results of such a calculation are as followsGENERAL AND PHYSICAL CHEMISTRY.23direction of approach is the energy of activation of the reaction.Corrections for change in the zero point energy of the molecules whichaccompanies the reaction must also be applied in a rough manner.The calculation of the course of the energy as the molecules approachfor “reaction” is simplified by the fact that London showed in ageneral way that reactions of the type Y + XZ require least activ-ation when the three atoms remain in a straight line. Eyring andPolanyi have estimated the heats of activation of the reactions H,(para) + H = H2 (ortho) + H; H + HBr = H, + Br; and H $Br, = HBr + Br. For the first they obtain 13 kg.-cals., for thesecond 10, and for the third zero.For the first the experimentalvalue is uncertain but lies between 4 and 11 kg.-cals. ; the second andthird are merely known to belong to the class of atomic reactionswith very small inertia.Eyring has made similar calculations for reactions of the typewhere X is a halogen. The numerical results are very uncertainbecause it is necessary to assume ad hoc that the Coulomb energy is36% of the total energy and the figure assumed makes a good dealof difference. The most interesting result, however, is a comparativeone independent of this assumption; namely, that the reactionbetween molecular iodine and hydrogen should occur more easilythan the reaction by way of iodine atoms, whereas with the otherhalogens the atomic mechanism is energetically preferred.This ofcourse is in striking accord with experiment.This is a convenient place to refer to the theory of adsorptioncatalysis of M. Born and J. Franck and M. Born and V. Weisskopf,21which, although not making use of actual potential-energy curves,depends upon general theoretical considerations concerning thepotential energy of molecules in relation to the atomic separations.The idea underlying the theory can be illustrated by an analogy. Ina homogeneous collision reactiqn two molecules must meet possessingthe energy of activation; quantum mechanically there is a finiteprobability of transformation by leakage 22 whether they possess thisenergy or not. But during the short time of a collision the probabilityis vanishingly small unless the energy is practically equal to orgreater than the activation energy : when adsorbed on a surface thesojourn of molecules in proximity to one another is long enough forthe probability of transformation to attain a finite value.Thetheory is thus a combination of the old chemical idea that thesurface keeps in proximity molecules which otherwise would havelittle opportunity to react and the principle underlying the GamowH2 + X = HX + H ; H + X, = HX + X ; X2 + X‘= XX’+ X21 2. phyeikal. Chem., 1931, [BJ, 12, 206; A., 576.22 Ann. Repom, 1930, 27, 2624 HINSHELWOOD :theory of radioactive change with its extensions to the spontaneouschemical changes in molecules.23 Born and Weisskopf take anidealised picture of a molecular rearrangement, namely two masspoints acting on each other with forces and capable of existing in twopositions of stable equilibrium at different separations.Thus therewill be two sets of states corresponding to various energy levels of theinitial and final products of the quasi-chemical rearrangement. I fthere were no interaction between the two sets of states the Schro-dinger equations for them would be independent, but a perturbationterm is introduced on account of the mutual potential energy of theatoms and the crystal surface on which they are assumed to beadsorbed. When there are two energy levels, one in the initial setand one in the final set, which correspond, transition by quantummechanical resonance occurs. The exact correspondence of energywould be extremely unlikelywithout the crystalsurface, which may actin one of two ways.It either takes up itself the difference between thetwo energies, or it makes the transition possible in virtue of the strongand variable mutual potential energy between atoms and surface. Arather elaborate calculation leads to the result that the probabilityof transition depends very markedly on the displacement which theatoms have to suffer in the process. If this is of the order of 0-5 A.it appears that the transformation can occur in a few seconds. Toarrive at this result special assumptions have to be made about theoscillation quantum numbers. The authors remark that this pictureof adsorption catalysis is not the only possible one : “ lowering of theenergy threshold, resolution of chemical linkages under the influenceof the adsorption forces, intermediate reactions with the atoms of thesurface, etc., may be essential factors.” It must be remarked herethat the experimental evidence has already shown that all thesefactors and especially the first are in fact of great importance.Howmuch room this leaves for the operation of the quantum mechanicalleakage phenomenon is a difficult question.A very different but equally interesting type of potential-energycurve is that representing the potential energy of an ct-particle inthe neighbourhood of a nucleus. When the distance is greater thanabout 10-12 cm., the particle is repelled in accordance with Coulomb’slaw, and the potential energy is represented by the part ab of thecurve sketched in Fig.2. For smaller distances the curve mustfollow a course such as bcd, eventually passing into the region of“ negative energy,’’ since a-particles inside nuclei are in fact in astable condition, and under the influence of attractive rather thanrepulsive forces.24 The shape of the curve nearer to the centre of23 Compare ,4nn. Reportcr, 1930, 27, 26, 317.24 G. Gamow, “ Constitution of Atomic Nuclei,” Oxford, 1931GENERAL AND PHYSICAL CHEMISTRY. 25the nucleus than b is a fascinating question connected with the mostfundamental problems of nuclear structure and stability. Atpresent only rough and tentative guesses can be made, but eventhese are proving helpful. For example, the course abet may bepostulated as an approximation, the potential energy being sup-posed to drop suddenly to the value in the stable position.Thetwo characteristic magnitudes are then x and y in the figure.H. M. Taylor,25 working on this basis, has shown that Rutherfordfand Chadwick’s results on the deviations of a-particle scattering inhelium from that required by the Coulomb law can be accountedfor if suitable values are chosen for the two constants z and y.Knowing these, the energy of binding of an a-particle inside anucleus can be estimated : here, however, the result is not quitesatisfactory, showing that the schematic simplilication is too greator is of an inappropriate form. It turns out that the energy lostwhen two a-particles unite to form a nucleus of mass 8 wouldcorrespond to a mass defect of 0.28%, which is very much too26 Pmc.Roy. SOC., 1931, [A], 134, 10326 HINSHELWOOD :large, compared with the known mass defects of elements such ascarbon and oxygen.Liquids and Solutions.Work continues on the properties of " intensively dried " liquids.The fundamental experimental fact, stated without prejudging anytheoretical issue, is that a liquid which has been sealed up withphosphorus pentoxide for a considerable time frequently will notgive a rapid continuous stream of vapour unless it is heated to aconsiderably higher temperature than would have been necessarybefore the drying process. This means either that some innerequilibrium in the liquid has been displaced, or that the rate ofevaporation from the liquid surface has been considerably lowered,rendering the liquid very liable to what is virtually superheating.26On general theoretical grounds the latter alternative appears muchmore probable, since it is easy to understand that during thestorage with phosphorus pentoxide either something (such as wateror colloidal dust particles) is removed which would have facilitatedevaporation, or that something (such as phosphorus pentoxideitself) is introduced which by concentrating itself in the surfacelayer impedes the free passage of molecules into the vapour phase.The former alternative would be very surprising from the thermo-dynamic standpoint, since it would mean that a small quantityof a foreign substance produced a change in free energy of thesystem out of all proportion to that produced by further additions.This would be extremely remarkable since thermodynamic functionsin general are linear in the concentration for small additions.Froma kinetic point of view it would also be remarkable, since if a verysmall addition of water produced a finite shift in equilibriumthrough the bulk of a liquid phase it would mean that each watermolecule exerted an influence far beyond the range of ordinarymolecular forces. This could only happen by some kind of trans-mitted polarising effect, the existence of which would imply thatliquids possess a " structure." J. W. Smith 27 has recently studiedthe distillation of ethyl bromide from one evacuated bulb to anotheracross a, constant-temperature gradient, and finds that the ratedecreases considerably as the '' drying " of the liquid proceeds.28The vapour pressure, however, remains unaltered, and moreover,there is no evidence of any fractionation of the dried liquid during26 Compare inter alia E.Cohen and W. A. T. Cohen-de Meester, Proc. K .Akad. Wetsnsch. Amsterdam, 1930, 33, 1003; A., 294; 8. Lenher, J . PhysicalChem., 1929,33,1579; A , , 1929,1372.2' J., 1931, 2573.28 Compare the work of R. Stumper, Kolloid-Z., 1931, 55, 310; A., 906,on the acceleration of evaporation by colloidal matterGENERAL m D PHYSICAL CHEMISTRY. 27distillation, such as would be expected if a shift in an innerequilibrium had occurred. This observation is parallel to that ofRodebush and Michalek, who some time ago observed that the rateof evaporation and of condensation of ammonium chloride werediminished by a process of drying.The earlier observation ofSmith and Menzies that dry calomel had zero vapour pressure alsomeans that the rate of evaporation was zero under the conditionsof the experiment rather than that the equilibrium value had beenreduced to nought. There are two analogies, differing in principle,in terms of which these various results may be explained. One isthe apparent zero value of the vapour pressure which would befound for slightly contaminated mercury a t ordinary temperatures,the other is the complete non-efflorescence of a perfect salt hydratecrystal in the absence of nuclei.The literature contains a number of confiicting results about theinfluence of drying on static properties such as surface tension andvapour pressure.(Miss) E. J. Greer 29 found that the addition ofvery minute traces of water to well-dried benzene gave rise to apartial pressure of several mm. a t 20" : this would indicate that ameasurable change in the total vapour pressure may occur withoutthe shifting of any equilibrium in the " dried " liquid itself.A. W. C. Menzies,30 on the other hand, finds that it is quite easyby simple distillation to free benzene from water to such an extentthat further changes in vapour pressure on further drying arenegligible. S. L. Wright, junr., and Menzies 31 have also failed tocodinn the existence of delays in the establishment of vapour-pressure equilibrium, or to find an influence of pre-treatment onthe boiling points of such liquids as benzene, carbon tetrachloride,and bromine. W.A. West and Menzies38 explain Baker's resultswith acetic acid, where changes of, vapour pressure were observedduring several days, as due to fractionation of a liquid containingsome water. Smits and others33 have recently shown that thecomplete removal of dissolved gases from liquids is a much morem c u l t matter than had been previously supposed. This raisesthe question whether a number of earlier observations on thechange of vapour pressure on drying are not redly to be explainedby the presence of permanent gases. Repetition of some of theearlier experiments has failed to show any change in the vapour20 J .Amer. Chem. SOC., 1930, 52, 4191; A., 34.30 J . Physical Chem., 1931, 35, 1655; A., 901.31 J . Arner. Chem. SOC., 1930,52, 4699; A., 1931, 294.32 J . Physical Chem., 1929, 33, 1893; A., 1930, 145.33 A. Smits, E. L. Swart, P. Bruin, and W. M. Mazee, 2. phyaikd. Chem.,1931,153,255; A., 43028 HINSHELWOOD :pressure when adequate precautions are taken to free the liquidsfrom gases.While no doubt a number of unexplained observations remain,the impression grows in strength that changes in static propertiesof liquids on “drying” are usually spurious effects, while thedynamic effects are genuine but not more mysterious than otherinfluences of nuclei, surface films, or catalysts.If some of the statements in the literature about the influence ofexcessively minute traces of impurity on the physical properties ofliquids are true, then it is difficult to escape the conclusion thatsomething of the nature of a structure exists in certain liquidsunder suitable conditions, and that infiuences from a single moleculeare transmitted by some kind of polarising influence, affecting stringsor clusters of molecules. Experimentally the situation is not unlikethat prevailing in psychical research where, we are told, most of theevidence can be ruled out, but a small obstinate residuum has tobe contended with.A matter of considerable interest in connexion with this generalquestion of the structure of liquids is the possible existence of twoliquid forms of certain substances.Two liquid forms of helium 34with a transition temperature depending on the pressure have beendescribed. From discontinuities in the curves showing the vari-ation with temperature of such properties as density, specific heat,viscosity, and dielectric constant, the existence of two liquid formsof nitr~benzene,~~ carbon di~ulphide,~~ and ether 37 has been inferred.But with nitr~benzene,~~ at least, careful re-investigation of theproblem indicates that the effects claimed are not real. It is t Qbe hoped that the phenomenon will be quite definitely establishedas real in certain examples or explained away in the near future.Among the most clarifying advances of the last ten years inphysical chemistry has been the recognition of the part played bypurely electrostatic forces in determining the properties of dilutesolutions of electrolytes. Conductivity, osmotic pressure, and thethermodynamic properties deducible from it, mutual solubilityinfluences of electrolytes, and the so-called salt effect on reactionvelocity all depend to a greater extent on the interionic forcesthan on any other single factor : indeed, the Debye-Hiickel theory34 W.H. Keesom and K. Clusius, Naturwiss., 1931, 19, 462; A , , 1004;Proc. K . Akad. Wetensch. Amtlterdam, 1931, 34, 605; A . , 1004.35 J. Mazur, Nature, 1930, 126, 993; 1931, 127, 741, 893; A . , 1931, 148,792, 899.36 M. Wolfke and J. Mazur, ibid., p. 926; A . , 896.37 J. Mazur, ibid., 1930,126, 649; 1931,127, 270; M. Wolfke and J. Mazur,38 N.B. Massey, F. L. Warren, and J. H. Wolfenden, J., 1932, 91.ibid., 1930,126, 684GENERAL AND PHYSICAL CHEMISTRY. 29of electrostatic interaction is so closely followed by many strongelectrolytes at high dilution that deviations from it can now beregarded, not so much in the light of a failure of a theory as ofuseful positive information about the intrusion of other specificfactors. These specific factors do in fact continue to reveal them-selves in a number of instances. For example, among the morerecent results are the following : in nitromethane solution tetra-ethylammonium salts behave in agreement with the Debye-Hiickel-Onsager theory of conductivity, but other salts, which behave asstrong electrolytes in alcoholic solution, are weak electrolytes innitromethane39 in spite of its greater dielectric constant.Thusmolecule formation is by no means controlled by electrostaticforces, even though the behaviour of ions can be predicted in termsof them if molecule formation does not actually occur.Two further important consequences of the Debye-Huckel theoryof interionic forces in dilute solutions have been investigated. Thefirst, relating to the viscosity of dilute solutions of electrolytes, isexplained in another section of the report. The second is that indilute solution the partial molar volume of an electrolyte, or therelated quantity, the apparent molecular volume, is proportional tothe square root of the concentration. In 1929 Masson 40 showed thatsuch a square root relation held for a number of electrolytes, andlater W.Geffcken4l elaborated. the matter. 0. Redlich and P.Rosenfeld42 have now shown that such a relation is a necessaryconsequence of the Debye-Eiickel theory. They derive theequationV: is the limiting value of the partial molar volume T2 at idbitedilution; w = QCv,zS2, where v, = number of ions of kind S permolecule, and z is the valency of the ion; q is a constant dependingupon the temperature, the dielectric constant of the solvent, thevariation of the dielectric constant with pressure, and the com-pressibility of the solvent. The " apparent molecular volume," 4, is related to the " partial molar volume " by the relation m G =d - ) , where m = the number of g.-mols. of solute per 1000 g.ofsolvent. For 4 the following equation holds : 9 = $0 + t q . w3I2. c*/~.From the examination of the experimental data made by Masson- - v, = v; + qUF= . c1'2-dm8s C. P. Wright, D. M. Murray-Rust, and (Sir) H. Hartley, J., 1931, 199;compare also the results for nitrobenzene, W. F. K. Wynne-Jones, ibid., p.795.40 (Sir) D. 0. Masson, Phil. Mag., 1929, 8, 218.41 2. phy8ikal Chem., 1931, [A], 155, 1.4a Ibid., p. 65; 2. EEektrochem., 1931, 37, 70530 HINSHELWOOD :and by Geffcken, the square-root relation appeared to hold for agiven electrolyte up to fairly high concentrations, but the slope ofthe curves exhibiting the relation varied from example to examplein an apparently individual manner. Redlich and Rosenfeld,examining the best experimental data, come to the conclusion,however, that at higher concentrations the lines are really curvedand that at great dilution they all converge to a single straight line,with the anticipated slope.While the best test can be made withthe data for uni-univalent electrolytes, the influence of the valencyfactor with multivalent electrolytes is, as far as can be seen,approximately in accordance with the theory. Examination ofdata for methyl-alcoholic solutions indicates that the influence ofthe solvent on the constant q can also be accounted for.There is no doubt that electrostatic forces may play a considerablepart in determining solubility, but it is also clear that their influenceis only one among many factors. By comparing theoretical pre-dictions of solubility, based upon a purely electrostatic theory,with the experimentally found relations, an idea can be formedof the importance of the electrical factor.The general principleunderlying such calculations is as follows. Some simple model ofan ion or molecule is adopted and its electrical energy in a mediumof given dielectric constant is worked out. The difference betweenthe electrical energies it possesses in two different media is thenequated to the work of transfer from one medium to the other,i.e., to ET In K , where K is the partition coefficient. Such calcul-ations are successful only in a very genera1 and qualitative way forionic partition coefficients. R. P. Bell43 has recently extendedthem to the solubility of dipole molecules, and thus obtained aninteresting picture of the extent to which the electric moment ofsuch molecules determines their behaviour.As a model he assumesa spherical molecule of dielectric constant unity, with a dipole a tits centre, the distance between the two charges of the dipole beingsmall compared with the radius of the sphere, He points out thatonly in rather extreme examples can the treatment give quantitativeresults, since it would predict, for example, equal solubilities fornon-polar gases such as hydrogen, oxygen, and nitrogen. Withstrongly polar molecules, such as ammonia and water, there is amuch better chance of success, and Bell finds for the relativesolubilities of these two substances in a number of solvents adependence upon the dielectric constant agreeing fairly well withthat anticipated by the theory, especially for the solvents of higherdielectric constant.For the solubility of the mercuric halides, regular relations areJ., 1931, 1371; Trane. Paraday Soc., 1931, 27, 797GENERAL AND PHYSICAL CHEWISTRY.31also found. The conditions under which the method of calculationis more or less adequate appear to be, therefore, when the dipolemoment of the solute is large, the dielectric constant of the solventis large, and also when the dipole molecule itself has a large diameter,since then the approximation involved in regarding the solvent asa continuous medium is better justified.As exemplified by examples referred to in a later section, theelectric moment of molecules does not appear to determine theiradsorption on surfaces to any important extent.However, asmight be expected, the degree of ionisation of a dissociable group inan interface influences the interfacial tension to a marked degree.The interfacial tension between aqueous and benzene solutions ofthe higher fatty acids varies with the hydrogen-ion concentrationof the aqueous phase over just the range which would be expectedif it were determined by the degree of ionisation of the unimolecularinterfacial layer, although in certain examples specific effects aresuperimposed. R. A. Petersu has recently shown that the inter-facial tension of the system benzene-water-hexadecylamine varieswith hydrogen-ion concentration in just the opposite sense to thatfor the long-chain acids, but over approximately the same range,and indeed that the interfacial-tension changes follow rather closelythe dissociation curve for a weak base.Here, therefore, we haveanother example of a phenomenon where electrostatic forces are ofpredominant importance.The Viscosity of Solutions of Electrolytes (by H. W. THOMPSON).Measurements of the viscosity of dilute solutions of electrolyteshave recently acquired considerable theoretical interest. TheDebye-Huckel interpretation of the conditions existing in suchsolutions, and the theoretical derivation of the Kohlrausch square-root relation between equivalent conductivity and concentrationwere based upon the idea that in the neighbourhood of any ionthere will be more ions of unlike than of like sign.The “ionicatmosphere” will normally be symmetrical, but will become dis-torted when the central ion moves. It possesses a c‘ thickness ”and requires a definite time for its establishment-these magnitudesbeing determined by the ionic concentrations, the valencies, thetemperature, and the dielectric constant of the solvent. Thevelocity of the central ion, moving under the influence of an electricfield, will depend on the properties of the atmosphere.It is not unnatural to suppose that the ionic atmosphere plays apart in determining the viscosity and in particular its variationwith salt concentration.44 Proc. Roy. SOC., 1931, [A], 133, 14032 KINSHELWOOD :The viscosity of liquids and solutions has been studied experi-mentally for a long time.Earlier workers confined themselvesprimarily to the construction of reliable viscometers : later workdealt primarily with the connexion between viscosity and molecularstructure, and with questions such as that of molecular association.Hubner first investigated the viscosities of a series of salt solutionsand found that addition of salt sometimes decreased the viscosityof the solvent. Sprung concluded that salts could be divided intotwo groups : those of the first depress the viscosity of water at lowtemperatures but increase it somewhat a t higher temperatures,while those of the second group always increase the viscosity.The work of Slotte, Arrhenius, Wagner, Ranken, and Taylor andGetman led to the suggestion of various empirical relationshipsexpressing the coefficient of viscosity, q, as a function of the con-centration.Griinei~en?~ working a t greater dilutions, discoveredthat the curves of viscosity plotted against concentration exhibita negative curvature a t the dilute end. He attempted, but not verysatisfactorily, to explain the results in terms of the electrolyticdissociation theory. M. P. Applebey 46 confirmed the existence of‘‘ negative curvature ” and also the fact that electrolytes maycause either an increase or a decrease in the viscosity of the solvent.He suggested that two opposing factors operate in determining theviscosity of a solution : on the one hand, there is a depolymerisationof triple water molecules which tends to decrease viscosity, and onthe other, there is ionic friction which increases it.With feeblyhydrated ions the second factor will be small compared with thefirst, and accordingly a net decrease in viscosity will be observed.I n general, however, ions will be hydrated to such an extent that,at any rate at the higher dilutions, a net increase of viscosity willbe found.G. Jones and M. Dole 47 have recently redetermined the viscositiesof solutions of barium chloride at various concentrations. Theirresults are not in agreement with any of the earlier empirical rela-tionships. While at the higher concentrations there is a certaindegree of proportionality between fluidity (reciprocal viscosity) andconcentration, yet a t the lower ones, i.e., in the region of the so-callednegative curvature, a systematic discrepancy exists.Jones andDole propose to account for this qualitatively as follows. Accord-ing to the Debye-Huckel theory of the ionic atmosphere, the effectof the interionic forces in opposing the motion of an ion in anelectric field is proportional to the square root of the concentration4ti Wise. Abhandl. Techn. Reichsanstalt, 1905, 4, 151, 237.46 J., 1910, 97, 2000.47 J . Amer. Chem. SOC., 1929, 51, 1073,2950; A., 1929, 767, 1385GENERAL AND PHYSICAL CHEMISTRY. 33in very dilute solutions. Thus for the fluidity the following rela-tionship is indicated : + = 1 + A d z + Bc. For all strong electro-lytes, A will have a negative value (the fluidity decreasing withconcentration), and for non-electrolytes it will be zero; B can onlybe regarded in the first instance as an empirical coefficient.Therelation can be re-expressed as (+ - l)[<c = A + Bdc, or if thehigher concentration term be neglected, q/qo = 1 + K&, where Kis a fresh coefficient.Jones and Dole re-examined the older data, which appeared toobey the relation, although there is a lack of data for high dilutions.They accordingly predicted that at high dilutions the viscosity ofsolutions of all strong electrolytes will be greater than that of purewater even in the case of salts which a t ordinary concentrationsshow a diminution of viscosity. This requirement was alreadysatisfied by the results of K. Schneider 48 working with solutions ofpotassium chlorate : an increase in viscosity occurred between 0and 0-05N, but at higher concentrations a falling off was observed.The same is true of nitric acid solutions, where W.Bousfield49found that at 11" and below N/32 the viscosity exceeds that ofwater. At higher temperatures the viscosity exceeded that ofwater at all concentrations examined.A mathematical investigation of the problem from the stand-point of the Debye-Hiickel theory enabled H. Falkenhagen andM. Dole 50 to derive the relation q/qo = 1 + K 6 . The simplecase of a uni-univalent electrolyte with ions of equal mobility wasfirst studied. The calculation leads to the resultK = (e/60q0udDx} x 0.491 x lolo,where e is the electronic charge, q the viscosity of the solvent, u thereciprocal of the frictional force acting on the ions, D the dielectricconstant of the solvent, k: the Boltzmann constant, T the absolutetemperature, and x the valency of the ions.H. Falkenhagen hasrecently extended the calculations to include any single ~ a l t . ~ 1The only salt with ions of approximately equal mobility ispotassium chloride, for which the calculated value of K is 0.0046.A series of theoretical values for various salts are given by Falken-hagen and Dole. W. E. Joy and J. H. Wolfenden52 have nowconfirmed the value of H predicted for solutions of potassiumThe latter form is now most common.4 8 Di88., Rostock, 1910.so Phyaikal. Z., 1929, 30, 611; A., 1929, 1389; 2. physikal. Chern., 1929[B], 6,159 ; A., 1930,155 ; also H. Felkenhegen, " Reviews of Modern Physics,"1931, 3, 412; Nature, 1931,127, 439; A., 560.5 1 2.physikal. Chem., 1931, [B], 13, 93; A., 905; Physikal. Z., 1931, 32,365 ; A., 686.63 Proc. Roy. SOC., 1931, [A], 134, 413.J., 1915, 107, 1781.REP.-VOL. XXVIU. 34 HINSHELWOOD :chloride, nitric acid, rubidium nitrate, and potassium chlorate.Some earlier determinations of the viscosity of rubidiumnitrate solutions by H. G. Smith, J. H. Wolfenden, and (Sir) H.Hartley 53 also exhibit the Falkenhagen-Dole effect. This effectprovides a further confirmation of the idea of the ionic atmosphere,and the influence of electrostatic forces in determining the propertiesof dilute solutions.Surface Chemistry.So many papers have been devoted to various aspects of surfacechemistry that it is necessary to devote a section again this yearto a few at least of the divisions of this rapidly expanding subject.The explanation of the nature of adsorptive forces in terms of thenewer theories of molecular forces has been discussed by F.Londonand M. P01anyi.~~ It appears, as one might have expected, thatthe dipole moment of the adsorbed molecule is of secondary import-ance only in adsorption phenomena, a conclusion which is supportedby the experiments of H. Cassel and F. Salditt 55 on the adsorptionof various vapours by mercury. It is also of interest to note inthis connexion that C. A. Sloat and A. W. C. Menzies 56 find theadsorption of various alkali bromides by lead sulphide not to berelated in any way to the lattice dimensions of the deposited salt.Three of the six salts examined give orientated deposits on leadsulphide, but there appeared to be no preferential adsorption ofthese.Among many other papers on the more general aspects ofadsorption phenomena may be mentioned a detailed discussion ofthe nature of the boundary layer in " lubrication " phenomena bySir W. HardyY5' in which chains of highly polarised moleculesstretching from one of the solid surfaces to the other are pictured.A general theory of the quantum mechanics of adsorptioncatalysis is dealt with in another section. has alsoderived a theoretical expression for the rate of a heterogeneous gasreaction, using assumptions analogous to those employed in theconsideration of homogeneous reactions : the results generally arein good agreement with experiment.Even if the details of Topley'scalculation are not accepted in their entirety, his results seem toshow that the introduction into the theory of adsorption catalysisof quantum mechanical " leakage " effects is far from necessary.On Dhe whole, much more work has been done on adsorptionconsidered as a statical (equilibrium) phenomenon than on theB. Topley53 J., 1931, 403.5 5 Ibid., 1931, 19, 110; A . , 421.5 6 J . Physical Chem., 1931, 35, 2022; A , , 904.6 7 Phil. TTans., 1931, [A], 230, 1 ; A., 559.6 8 Nature, 1931, 128, 115; A., 918.64 Naturwiss., 1930, 18, 1099; A., 1931, 161GENERAL AND PHYSICAL CHEMISTRY. 35dynamical aspect of the process.We may, however, now considersome papers dealing with this important side of the subject. Ex-periments on the exchange of energy between helium atoms andsurfaces of tungsten and of nickel are described by J. K. Roberts,59the method of investigation being that of studying the heat lossfrom a wire of the metal surrounded by the gas. The accommodationcoefficient is found to vary with the state of adsorbed gas films onthe wires. T. Alty,SO by measuring the rate of evaporation from awater surface and extrapolating to zero pressure, obtains the idealrate of evaporation into a vacuum : by comparing this with therate a t which molecules strike the surface from the saturatedvapour it is found that, in order that there may be equilibrium,only about 1% of the incident molecules actually enter the liquid.G.Veszi 61 estimates that when the atoms in a metal vapour arereflected from the surface of a stream of oil, they sojourn in somecases for a period of the order of 104 to 10-5 see. on the oil surface.An interesting relation between catalysis and accommodation comesto light in the work of K. F. Bonhoeffer and A. Parkas 62 on thetransformation of para-hydrogen into the equilibrium mixtureunder the influence of a heated platinum wire. The suggestedmechanism of the catalysis is that the para-hydrogen is adsorbedby the metal in the atomic form, and that re-evaporation in themolecular form subsequently takes place, ortho- and para-hydrogennaturally coming off in the equilibrium proportion.The usualplatinum catalytic poisons inhibit the transformation, while a traceof oxygen accelerates it. Now at lower temperatures, where nocatalysis occurs, heat exchange between the wire and the gas takesplace only by the process of reflexion of molecules from the surface.But a t higher temperatures adsorption of the striking moleculesand their subsequent evaporation play a considerable part in theenergy exchange, and one finds that the accommodation coefficient,as inferred from the amount of electrical energy required to main-tain the wire at a given temperature, increases abnormally, and thatthis increase sets in just as the catalytic activity appears. Poisonedplatinum a t the same temperatures continues to show a normalcoefficient.Under normal conditions both direct experiment and indirectevidence from the kinetics of heterogeneous reactions show that therate at which an adsorption equilibrium is established is very great.Slow processes are usually interpreted as solution phenomena or59 Proc.Roy. SOC., 1930, [ A ] , 129, 146; A., 1930, 1340.60 Ibid., 1931, [A), 131, 554; A,, 904.62 Ibid., 1931, [B], 12, 231; A., 691.2. physikab. Chem., 1930, [B], 11, 211; A., 1931, 16236 HINSHELWOOD :chemical changes. H. S. Taylor 63 has, however, recently suggestedthat these slow changes are of more fundamental importance thanhas hitherto been assumed. He says “there are now numerousdata showing abnormal variations in the extent of adsorptionwith both temperature and pressure, large variations in the velocityof attainment of equilibrium in different adsorption systems andin the velocity of evaporation of adsorbed gases inconsistent withthe present adsorption theory.” Taylor suggests that true adsorp-tion per se is not necessarily a rapid process, but one which takesplace with a characteristic velocity determined by the same kindof factors as those which govern the rate of chemical changes, andin particular that an activation energy may in some cases benecessary for a molecule to be adsorbed by a surface.He pointsout that a diatomic molecule can in principle be adsorbed in twoways, either molecularly or with accompanying resolution intoatoms. The first kind of process would be expected to have a verysmall heat of activation, but the second may well require theabsorption of very considerable amounts of energy; it would thusbe improbable a t low temperatures, but would have a high temper-ature coefficient.Some of the conclusions which may be drawnfrom these postulates are as follows. At low temperatures molecularadsorption will predominate, the total amount adsorbed in this waydecreasing as the temperature rises. In a certain higher range oftemperature the total adsorption increases again, not on account ofchanged equilibrium conditions, but because the veZocity of theactivated atomic adsorption, hitherto negligible, now becomes appre-ciable. In this region equilibrium will not be attained instan-taneously, and it may be found that the large amounts of gastaken up at a higher temperature are more or less tenaciouslyretained on rapid cooling to a temperature where they would notoriginally have been taken up.Furthermore, the heat of adsorp-tion will vary with temperature according to whether the molecularor the atomic type of adsorption is predominating. Some examplesof the evidence that effects of this kind are indeed observed maynow be quoted. The adsorption of hydrogen by nickel above- 100” is rapid : at lower temperatures, A. F. Benton and T. A.WhiteG4 found the adsorption a t a given temperature to varyaccording as the saturation was effected at the actual experimentaltemperature or at a higher one with subsequent cooling. Between- 183” and - 191” adsorption was rapid but a t higher temperaturesit was slower, suggesting according to Taylor’s point of view that aprocess with an activation energy is coming into play.Taylor63 J . Arner. Chern. SOC., 1931, 53, 578; A., 421.64 Ibid., 1930,52,2326; A., 1930, 990GENERAL AND PHYSICAL CHEMISTRY. 37quotes other evidence of a similar kind, such as the diminishingadsorption by platinum as the temperature falls, the “ plurality ofprocesses ” involved in the fixation of oxygen by charcoal, and thehysteresis phenomena observed in the adsorption of oxygen bysilver and gold.It will be readily admitted that the processes postulated byTaylor may in principle play an important part in adsorptionphenomena, and that the conclusions he draws from his postulatesare correct. But it is open to considerable doubt at the momentwhether the experimental observations which he quotes in his firstpaper are really to be identified with the operation of such pro-cesses. It is necessary first to show that, the abnormal temperatureinfluences and the hysteresis effects are not really due to solution.Taylor argues that the amounts of gas involved are higher than theknown solubilities, and that in these adsorption effects the surfacefactor is all important, which it would not be in a solubility pheno-menon.But to this must be said that it is not a question of theequilibrium solubility, but rather of rate of solution. At lowtemperatures the penetration of a gas into the lattice of a, metalwill in general be excessively slow: at higher temperatures theporosity increases and gas can penetrate a few layers of atoms notfar removed from the surface, especially when the surface structureof the metal has been loosened and to some extent opened up byvarious chemical or physical treatments. Where gas has oncepenetrated, gas can penetrate again more easily than before, andin the case of a metal which has had the outer layers of its massopened up, we may have a fairly easy absorption or removal of gaswhich appears something like the rapid establishment of anequilibrium.But this is very far from being the true solubility :persevering treatment at higher and higher temperatures will makethe metal more and more porous. It is improbable that with amassive metal the true solubility would be attained except underquite exceptional conditions, so that Taylor’s argument about themagnitude of solubility effects seems inconclusive.Increasinglygreat ease of penetration of metals by gases as the temperaturerises (the penetration being in any case slow and difficult, and,moreover, retarded by the gas already taken up), is a, factor whichundoubtedly must be taken into account, and which will inevitablymask the effects discussed by Tayl0r.6~ These important effectsought, however, to exist, and it may be possible with experimentalwork of some delicacy to isolate them from the other complications,as we shall see below in dealing with some of the most recent work.(It may be remarked here that failure of the so-called Polanyi-65 Compare E.W. R. Steacie, J . Physical Chem., 1931,35, 2112; A., 90438 MNSHELWOOD :Hinshelwood equation G6 when a measured heat of adsorption isused does not necessarily indicate that another energy term, Taylor'sactivation energy of adsorption, is to be introduced. Accordingto Taylor's well-established theory of active points, the heat ofadsorption on the active points responsible for the catalysis willnot bear any definite relation to the average heat of adsorptionrevealed by a calorimetric measurement .)In pursuing the idea of activated adsorption, Taylor and William-son 67 have found some interesting results on the adsorption ofhydrogen by manganous oxide and manganous oxide-chromiumoxide mixtures. The process is slow with manganous oxide at 0"and loo", and between 184" and 305" increases in rate ten-fold,corresponding to a " heat of activation " of about 10,000 calories :with the promoted oxide both kinds of adsorption can be studied,one with a negligible "heat of activation" and the other withthe high and variable value for this quantity.The adsorption isreversible. W. E. Garner and F. E. T. Kingman 68 find that acatalyst of zinc and chromium oxides adsorbs hydrogen and carbonmonoxide a t low temperatures " without dissociation of the mole-cules," whereas above 100" the adsorption becomes irreversible andthe gases can only be removed as water or carbon dioxide.F. E. T. Kingman has also made observations on the criticalincrement of adsorption of hydrogen by charcoal. 69In connexion with the discussion of the part played by actualpenetration, rather than surface adsorption, in the processes classedunder the general heading of sorption, the work of M.G. Evans 70on the sorption of ammonia by chabazite is of great interest. Hefinds that when ammonia is taken up the X-ray diagrams of thechabazite show distortion of the space lattice. This distortion,caused by actual penetration of the ammonia molecules, mayultimately shatter the crystal. While it is not probable that allslow sorption depends upon such effects, this work shows thatspecific allowance for the possibility of such penetration must bemade in any given example.In certain examples, notably with oxygen and charcoal, the heatof adsorption for the first portions of gas taken up is greater thanfor subsequent portions.A. F. H. WardY7l however, has foundthat the heat of adsorption of hydrogen by activated copper isindependent of the concentration of gas on the surface. In these6 6 J. K. Dixon, J. Amer. Chem. Soc., 1931, 53, 17G3; A., 803; H. Dohse67 H. S. Taylor and A. T. Williamson, J . amer. Chem. SOC., 1931, 53, 813,6 8 Trans. Faraday Soc., 1931, 27, 322.70 Proc. Roy. SOC., 1931, [ A ] , 134, 97.and W. Kalberer, 8. physikal. Chem., 1929, [B], 5, 131 ; A., 1929, 1231.2168 ; A., 421,902.69 Nature, 1931, 128, 272.7 1 Ibid., 1931, [ A ] , 133, 506, 522GENERAL AND PHYSICAL CHEMISTRY. 39experiments there was a clear separation observable between theinstantaneous adsorption and a slow subsequent process of solution.Ward adduces evidence to show that the dissolved hydrogen is notsplit up into atoms as has often been supposed, and also givesreasons for supposing that penetration of the copper by the hydrogenoccurs by diffusion along the boundaries of metal grains ratherthan by diffusion into the lattice.These considerations are relevantalso in connexion with the above remarks on Taylor’s views.An interesting new method of investigating surface films hasbeen developed by J. H. Schulman and E. K. Ridea1,72 followingup a technique introduced by Guyot and by Frumkin. Thepotential difference at the surface of an aqueous solution bearinga thin film of a substance such as a fatty acid is measured electro-metrically, one electrode being a calomel electrode making contactwith the liquid in the trough, the other being an air electrode,consisting of a metal plate above the solution with the interveningair gap ionised by a radioactive preparation.The acidity of theaqueous layer can be varied, the state of compression of the filmcan be altered as in the Langmuir-Adam trough, and the variationsin surface potential studied, Theoretically the difference ofpotential at the surface is given by AV = 4mp, where n is thenumber of molecules per sq. cm. of surface and p is the effectivevertical component of the average electric moment. By thismethod transitions, for example, from vapour to liquid expandedfilm can be observed. The values of p in different states 6f thefilms can be found and conclusions can be drawn about the structureand configuration of the films.The authors give evidence for theexistence of a new phase appearing in the transition from theliquid to the vapour state of films of fatty acids. There are alsoindications that in the vapour films the molecules are horizontallyorientated.A. J. Allmand and others 73 have continued a detailed andsystematic study of the adsorption isotherms of gases and vapours.One of the most important results 74 of the more recent of theseinvestigations is the strong indication found that the adsorptionof vapours by porous solids such as charcoal is definitely discon-tinuous in nature : the curves representing amount adsorbedplotted against pressure of the vapour in the gas phase showingbreaks, or even horizontal steps where the amount adsorbed72 PTOC. Roy.SOC., 1931, [A], 130, 259, 270, 284; A., 299.73 A. J. Allmand and R. B. King, ibid., p. 210; A., 160; A. J. Allmand andA. Puttick, ibid., p. 197; A., 160.7 4 A. J. Allmand and L. J. Burrage, ibid., 1931, [A], 130, 610; A., 558;compare also A. F. Benton and T. A. White, J . Amer. Chem. SOC., 1931, 53,2807; A., 100540 HINSHELWOOD :increases suddenly for a small increase of pressure. The inter-pretation of these observations depends upon the fact that thesurfaces possess regions of different adsorptive power, and uponthe fact that the adsorbed vapour may change from a two-dimen-sional gas to a two-dimensional liquid at certain critical pressures.Mention should also be made of the work of N.I. Kobosew andW. L. A n ~ c h i n , ~ ~ who study adsorbed gas films by the method ofelectron bombardment, measuring, not the ionisation potential ofthe adsorbed gas as in the experiments of J. H. Wolfenden 76 andof G. B. Kistiak~wsky,~~ but the actual rate at which the gasbecomes desorbed under the influence of the electron stream.While the interpretation of some of their observations seems alittle speculative, it is interesting to note that Kobosew and Anochindistinguish three " desorption potentials " of hydrogen fromplatinum, corresponding to the release of the gas from plane sur-face, edges, and corners of the solid respectively. Complex relationsare found when oxygen and hydrogen are simultaneously presenton the surface.Xtructure of Natural Products.As an example of the way in which complex natural structuresare being investigated, reference may be made to the work ofJ.B. Speakman 7* on the micelles of wool fibre. The methodsused are interesting : the elastic properties of wool fibres in dryair and in water are quite different; fibres in methyl or ethylalcohol behave as in water, while fibres in butyl or amyl alcoholbehave as though dry. Thus the capillary space in the wool fibreis probably of about the same size as the molecule of propyl alcohol,in which liquid an intermediate behaviour is found. When ittakes up a liquid, a wool fibre may swell and subsequently beable to take up another liquid which could not have penetratedinto the dry wool.By studying the elastic properties of the fibresin mixed liquids, information about the structure of swollen fibrescan be obtained. This is supplemented by observations on changeof length on swelling, comparison with X-ray data, and deductionsfrom various other facts to give a detailed picture. The woolfibres have a " plate-like " structure, and are arranged with theirlong axes parallel to the fibre length: they are probably aboutten times as long as thick. The micellar thickness is about 200 8.,and the intermicellar distance about 6 A., increasing on swelling in7 5 2. physikal. Chern., 1931, [B], 13, 63; A., 903.7 6 Proc. Roy. SOC., 1926, [ A ] , 110, 464; A., 1926, 217.7 7 J.PhysicalChem., 1926,30, 1356; A., 1926, 1188.7 8 Proc.Roy. SOC., 1931, [ A ] , 132, 167; A., 1003GENERAL AND PHYSICAL CHEMISTRY. 41water to about 41 8. This makes the internal surface of woolsomething of the order of a million sq. cm. per gram.An extremely interesting account of X-ray studies of hair andother animal fibres has been published by W. T. Astbury andA. Street,79 who find that all animal hairs appear to give sub-stantially the same X-ray diagram. When the hair is stretched,one form of X-ray photograph (the " a ") gives place to another(the " p ") corresponding to a unit cell of quite changed dimensions.This transformation seems to depend upon the reversible change ofa certain group of length 5.15 8. into another of length 6.64 a.,and plays a very important part in determining the elastic propertiesof hairs, which are in many ways remarkable.The " p " form ismore vulnerable to the attack of sodium sulphide, and in thisconnexion it is a suggestive fact that the most intense X-rayreflexion given by stretched hair has the same spacing as the mostimportant reflexion which the substance cystine gives. In thiswork we see, however incompletely, that interrelation of micellarstructure, chemical structure and behaviour, and mechanicalproperties upon which the function of living matter must depend.Chemical Kinetics.In the Annual Report for 1927 it was remarked that if the theoryof collisional activation in unimolecular reactions proved to begenerally applicable, then the distinction between unimolecularand bimolecular gas reactions would become one of degree only.This anticipation i s apparently being fulfilled, and the classicaldivision of reactions into orders is losing a good deal of its signifi-cance.Naturally in a change of the type X + Y = XY we stillhave a bimolecular reaction in the older sense, but complicationsarise in reactions of the types XY = X + Y, and 2XY = X, + Yz.In all known thermal reactions of the first of these two latter types,activation is by collision (though in principle we can hardly yet ruleout the possibility that real non-collisional unimolecular changesmay be discovered), and thus these changes do not differ in principlekinetically from those of the second type. The essential differenceis merely one in the time which elapses between activation andreaction, and therefore in the relative importance of deactivationof the active molecules by subsequent collision before the chemicaltransformation has occurred.In general we may say: rate ofactivation = k,c2; rate of deactivation = k,c . a, where u is theconcentration of active molecules ; rate of actual chemical trans-formation = k,a. For a stationary concentration of active mole-713 Phil. Tram., 1931, [ A ] , 230, 75; A., 897.B 42 HINSHELWOOD :cules k1c2 = E,c . a + E3a; whence the rate of reaction is Ic3a =klc2/(1 + k 2 / k 3 . c ) . According as the ratio E2lI1.3 is great or small,the reaction approximates to the classical unimolecular or bimole-cular type. Only when the chance of deactivation is absolutelyzero can the reaction remain bimolecular up to indefinitely greatpressures.I n reactions of the type 2XY = X, + Y, this con-dition might be fulfilled if both molecules had to be transformed atthe moment of impact or never, as, for example, when the processXY = X + Y is energetically impossible. Even here, however,deactivation at really high pressures could occur by ternary collision,so that in general we must not expect simple definite orders ofreaction, but only approximations to a given order in a givenregion of pressure. The principle that simple molecules givebimolecular reactions while complex molecules give unimolecularreactions should be stated in the form that complex moleculesundergo reactions which become kinetically unimolecular at rela-tively low pressures while simple molecules react bimolecularlyup to relatively very high pressures.Turning to some of the recent experimental evidence illustratingthese ideas, we may first take the decomposition of nitrous oxide.When this was first investigated, a reaction depending upon collisionof two molecules was called bimolecular, and unimolecular reactionswere supposed to be changes of isolated molecules produced by anagency such as radiation: in this sense the decomposition ofnitrous oxide proved to be definitely bimolecular.However, overits whole course the reaction did not give good bimolecular con-stants, nor did the straight line obtained by plotting the reciprocalof the time of half change against the pressure pass through theorigin, as it should in a classically perfect bimolecular reaction :complicating factors were known to exist.N. Nagasako andM. Volmer,go making measurements up to pressures of 10 atmo-spheres, state that the reaction tends to become kinetically uni-molecular. H. C. Ramsperger and G. Waddington,gl treating thereaction as a quasi-unimolecular one, show that only two squaredterms are involved in the activation process, so that the reactionstill belongs to the category of those with a simple activationmechanism. Whether we should regard the actual process of thechemical transformation a t higher pressures as N,O = N, + 0, orwhether the chemical process is still to be regarded as essentially2N,O = 2N, + 0, with a marked deactivation at high pressuresby ternary collisionsthe binary collisions being assumed to havea small but finite duration-is a t the moment an open question.2.physikal. Chem., 1930, [B], 10,414; A . , 1931, 174.Proc. Nut. Acad. Sci., 1931, 17, 103; A . , 671GENERAL AND PHYSICAL CHEMISTRY. 43If the former is the real mechanism it is very interesting, since a tquite low pressures another homogeneous unimolecular decomposi-tion of nitrous oxide has recently been detected.sa Thus therewould be two independent modes of activation of the N,O molecule.The decomposition of ozone,83 bimolecular as ordinarily measuredin the gas phase a t comparatively low pressures, becomes uni-molecular in carbon tetrachloride solution. While it is possiblethat the mechanism of the solution reaction may be quite different(involving a chain process in which the solvent takes part) there isat least an interesting possibility that the solvent merely acts asan enormous concentration of inert gas, and so aids the quasi-unimolecular reaction of ozone to attain its limiting unimolecularrate, the action being analogous to that of hydrogen and otherinert gases on certain gas reactions definitely known to be of thequasi-unimolecular variety.Further interesting examples of quasi-unimolecular reactions havebeen discovered.In the unimolecular decomposition of germaniumtetraethyl,M the rate of reaction begins to fall off at about 70 mm.The limiting velocity is given by the expression In k = 32.8 -51,00O/RT; 8-10 degrees of freedom appear to be involved in theactivation process.The thermal decomposition of dimethyltri-azene 85 is a homogeneous reaction of the same type; the ratefalls off a t initial pressures of about 10 mm., the constant beinggiven by Ink = 26.74 - 33,80O/RT.H. J. Schumacher and G. Sprenger 86 have studied the thermaldecomposition of nitryl chloride, 2N0,CI = 2 N 0 , + Cl,, which theydescribe as a reaction of the first order. As far as the influence ofpressure on the rate of change goes, it approximates much moreclosely to a reaction of the second order, since the influence ofpressure on the unimolecular velocity constants even at 10 atmo-spheres shows no sign of diminishing (as it should in a quasi-unimolecular reaction). Moreover, the relation between the heatof activation and the absolute rate of change is more nearlycharacteristic of reactions of the bimolecular type.The heat ofactivation is 20,500 calories. Taking, for example, the experi-mental data for 140" and 506 mm., the number of molecules whichwould react in a simple bimolecular reaction with activation in82 F. F. Musgrave and C. N. Hinshelwood, Proc. Roy. SOC., 1932, in the8s E. J. Bowen, E. A. Moelwyn-Hughes, and C. N. Hinshelwood, ibid., 1931,84 R . L. Geddes and E. Mack, J . Amer. Chem. SOC., 1930, 52, 4372; A.,8 5 H. C. Ramsperger and J. A. Leermekers, ibid., 1931,53,2061; A . , 916.86 2. physikal. Chem., 1931, [B], 12, 115; A., 1931, 915; ibid., 13, 267.press.[A], 134,211.1931, 7844 HINSHELWOOD :two squared terms only is about 5 x 1017, while the actual numberreacting is about 2.3 x Thus we are within about one powerof ten of the theoretical number ; this is more characteristic of the" bimolecular " region than of the " unimolecular " region.The authors apparently prefer t o call the reaction unimolecular,principally because the complete course of the change for a giveninitial concentration is adequately described by an equation of thefirst order.But it appears also that the products of reaction havea specific accelerating influence, so that this constancy of theunimolecular k must be largely accidental. Although this matteris really one of nomenclature, it is mentioned here because a gooddeal of confusion sometimes arises now about the use of the term" order of reaction " and some convention should perhaps be agreedon.As a result of complications due to catalysis by products andso on, the order deduced from the influence of the initial concen-tration is not always the same as that which gives the best equationto express the course of the reaction with time for a given initialpressure. This comes to light particularly clearly in the nitrylchloride reaction. It seems to the reviewer that the more significantorder is that which describes the influence of changing pressure.The slow decomposition of diazomethane 87 between 140" and220" is stated to be bimolecular ; probably over an extended rangeof pressures the order would also prove variable here. The thermaldecomposition of methane, according to G.C. Holliday and W. J.Gooderham,88 takes place in two stages in the first of which twomolecules of methane react together to give C,H,. Interestingpreliminary observations 89 on the reaction C1, + Br, = 2BrC1indicate that it may be a bimolecular reaction proceeding accordingto the simplest possible law, with a heat of activation of about14,000 cals.The observation 90 that the decomposition of nitrogen pentoxideceases entirely below a certain pressure does not appear t o becorrect, though a definite falling off in the specific rate in the neigh-bourhood of 0-06 mm. now seems to be e~tablished,~~ in accordancewith theoretical expectations. This reaction therefore is also of thequasi - unimolecular class.E. W.R. Steacie, J. Physical Chern., 1931, 35, 1493; A., 916.** J., 1931, 1594; A., 915.89 W. Jost, 2. physikal. Chem., 1931, [BJ, 14, 413.O0 C. Sprenger, ibid., 1928, 136, 149; A., 1928, 1099.01 H. C. Ramsperger and R. C. Tolman, Proc. Nat. Acad. ScG, 1930, 16,6 ; A., 1930,547; H. J . Schumacher and G. Sprenger, ibid., p. 129; A . ,1930, 708; J. H. Hibben, J. Physical Chem., 1930, 34, 1387; A., 1930, 1127;J. H. Hodges and E. F. Linhorst, Proc. Nat. Acad. Sci., 1931, 17, 28; A,,436GENERAL AND PHYSICAL CHEMISTRY. 45If it turns out to be true that quite simple molecules such as N,Ocan survive the activating collision and decompose spontaneouslygiving a free atom after a certain finite lapse of time, then thereverse process, namely, the combination of two simple structuressuch as atoms to give one molecule, becomes a thermodynamicnecessity.In these circumstances the generally accepted principlethat ternary collisions are necessary for- combination between twoatoms to occur loses its general validity. According to M. Volmer 92the newly formed molecule may be in a state where the quantisationof vibrational energy is no longer sharply defined. If this is so thenecessity of the ternary collision to allow the correct adjustment ofthe energy of the molecule formed t o the quantum requirements nolonger exists.An interesting study has been made by G. B. Kistiakowsky andM. Nelles 93 of the slow isomerisation in the gas phase of dimethylmaleate into dimethyl fumarate, which occurs in the region of300".The reaction is of the quasi-unimolecular type, but unlikemost reactions of this kind it shows an abnormally small rate, beingonly about 103 of that calculat'ed on the assumption that twosquare terms are involved in the activation process. Thus, not onlyare the degrees of freedom of the molecules mostly inactive, but inaddition a great many of the collisions are from the chemical pointof view inelastic.In the following will be briefly summarised a few results ofoutstanding importance in connexion with the mechanism ofchemical reactions.D. L. Chapman and F. B. Gibbs 94 have shown that if chlorine issufficiently purified from oxygen it combines with hydrogen at arate proportional to the square root of the light intensity. This isbecause the chlorine atoms propagating the reaction chains areremoved by recombination rather than by the chemical action offoreign substances (as occurs in the incompletely purified gasesj.Thus the hydrogen-chlorine combinations falls into line with thecorresponding bromine reaction, the rate of which is usually pro-portional to the square root of the intensity, but becomes propor-tional to the fist power of the intensity in the presence of certaindeliberately introduced impurities.In connexion with the well-known induction period in the hydrogen-chlorine reaction, shownlong ago by Chapman to be due to the presence of nitrogen tri-chloride, it should be mentioned that the photosensitised decompos-ition of this latter substance has been studied by J.G. A. Griffithssa 2. phyaikal. Chem., 1931, [BJ, 13, 299.O3 Ibid., 1931, Bodenstein Festband, p. 369; A., 1230.s4 Nature, 1931,127, 854; A,, 80646 HINSHELWOOD :and R. G. W. NorrishYs5 and correlated with the inhibition of thehydrogen-chlorine combination. M. Bodenstein and W. Unger 96have discovered another mechanism by which the chains in thephotochemical hydrogen chloride formation are broken, namely, adirect chemical reaction in t'he gas phase between some of thechain carriers and a gaseous silicon compound formed by theaction of activated chlorine on the glass or silica walls of thevessel.Franck and Bodenstein 97 have suggested the following modific-ation of the Nernst chain in the combination of hydrogen andchlorine :(1) c1, + hv = 2c1;(2) C1+ H20 + H, = HCl + H,O + H ;(3) H + C1, + H, = 2HC1+ H ;(4) H + 0, + H, = H,O + OH;(5) H + 0, + C1, = HCl + (210,.For the rate of reaction this scheme gives the equationwhich expresses adequately most of the experimental results ( I isthe intensity).The chief experimental reason for introducing thenew hypothesis is the necessity for the presence of a small con-centration of water vapour reported by Coehn and Jung. Thusstep (2) is one of the simplest reactions which can follow (1) if ahydrogen atom is to be produced as in the original Nernst chain.The concentrations of steam molecules and chlorine atoms are,however, very minute, and if it be supposed that at each step inthe cycle of changes a chlorine atom and a steam molecule mustmeet, there is the greatest difficulty in accounting for the observedrate of reaction. To avoid this difficulty, chlorine atoms areassigned no r6le except in the first link of the chain, the subsequentsteps all depending on the reaction and re-formation of hydrogenatoms in the series of termolecular processes represented above.It is also interesting to note that the photochemical formation ofhydrogen chloride takes place with an effective quantum yieldwhen the light is absorbed in the band region of the chlorinespe~trum,~8 i.e., where activated molecules and not free atoms are9 5 Nature, 1931,127, 14; Proc. Roy.Soc., 1931, [A], 130, 591; A., 179, 578.B6 2. physikal. Chem., 1930, [B], 11,253 ; A . , 1931, 319.9 7 M. Bodenstein, Faraday Society, Liverpool Meeting, 1931 ; Trans.98 E. Hertel, 2. physikal. Chem., 1931, [BJ, 14, 443.FaraduySoc., 1931, 27, 413; A., 1136(3ENERA.L AHD PHYSICAL CHEMISTRY. 47primarily formed. These molecules are supposed to give atoms insubsequent collisions.The following investigations illustrate interesting points ofprinciple in connexion with the theory of chain reactions. H. W.Melville and E. B. Ludlam 99 have studied the influence of a longseries of foreign gases on the lower critical limit encountered in theoxidation of phosphorus vapour, and have established a definitecorrelation between the influence of the gas and the diffusioncoefficient through it of the chain-propagating molecules, thus con-firming the view that at the critical limit the branching of thechains just ceases to be kept in check by deactivation at the wall ofthe vessel. In this connexion also reference may be made to anelaborate mathematical treatment of chain reactions by theapplication of the classical diffusion equations.A curious phenomenon shown by mixtures of hydrogen sulphideand oxygen has been observed by H. W. Thompson : underappropriate conditions a series of successive explosions takes place,each being preceded by an increasing time lag. The effect seems tobe connected with the formation of a catalytic substance during aninduction period and the occurrence of an explosion when a criticallimit is reached, the explosion being incomplete, however. Duringan ensuing induction period a critical concentration is againreached.Norrish3 has observed a sharp limiting pressure of chlorine inmixtures with hydrogen and oxygen above which an explosionoccurs when the gases are exposed to the light of a mercury lampat 300".In the last report reference4 was made to the fact that atomicreactions of the type Na + C1, = NaCl+ C1 may not alwaysoccur without activation, as the work of Polanyi and others ondilute alkali metal-halogen flames had suggested. The wholequestion has been dealt with in a paper by H. von Hartel andM. P ~ l a n y i , ~ who find that in the reactions between sodium vapourand the methyl halides the activation energy is nil for the iodideand rises regularly through the bromide and chloride to the fluoride.There is also an appreciable " inertia " associated with the reactionbetween sodium vapour and cyanogen, but since this is independentV. Bursian and V . Sorokin, 2. physikal. Chem., 1931, [BJ, 12, 247; A.,2 Nature, 1931,127,629; A., 689; also H. W. Thompson and N. 8. Kelland,99 Proc. Roy. SOC., 1931, [A], 132, 108; A., 1014.688.J., 1931, 1809; A., 1014.Nature, 1931,127, 853; A., 805.Ann. Reports, 1930, 27, 20.5 2. physikal. Chem., 1930, B, 11, 97 ; A., 17448 GENERAL AND PHY SIC& CHEMISTRY.of temperature it must depend upon some kind of " steric ) ) factorrather than upon the necessity for ,activation. Although theprinciple that atomic reactions do not require activation ceases t obe absolute, it remains true to say that many such reactions doproceed without activation, and also that the heat of activation ofothers is generally quite small.C. N. HINSHELWOOD

ISSN:0365-6217    

DOI:10.1039/AR9312800013

出版商:RSC    

年代:1931

数据来源: RSC

摘要:

INORGANIC CHEMISTRY.THERE has been a steady output of papers on Inorganic Chemistryduring the past year but rather smaller in amount than for someyears past. The discovery of the missing alkali metal-No. 87-byJ. Papish has been announced,l but it is not possible at present tosay whether the claim rests on any sound basis. Optically activecompounds of nickel have been prepared which owe their activityto six-co-ordinated nickel.2 Reports on all atomic-weight work inthe previous year will in future be issued at the beginning of eachyear by the Committee on Atomic Weights of the InternationalUnion of Chemistry. This makes it unnecessary to consider atomic-weight determinations in the present Report. The first report onatomic weights under the new r6gime dealt with work publishedduring 1930 and was issued in June.3The other special topics which have been considered in the lasttwo annual reports no longer seem to call for special mention, andany paper bearing upon them, to which it is desired to refer, will bementioned under the group of elements most directly affected.Group 0.The transition temperature of the two forms of liquid helium islowered as the pressure is in~reased.~ Further details have beenpublished of improved methods of extracting krypton and xenonfrom liquid-air residues, and of the redetermination of variousconstants.5Group I.It is becoming increasingly evident that the peculiar effects onthe boiling of liquids produced by very complete removal of tracesof moisture are due to superheating and not to a true elevation ofboiling point brought about by some disturbance of the inner1 See note in Nature, 1931,128, 696 ; J.Papish and E. Wainer, J . Amer.Chem. SOC., 1931,53,3818 ; A., 1348.2 G. T. Morgan and F. H. Burstall, J., 1931,2213; A., 1168; Nature, 1931,127, 854; A., 895.J., 1931,1617.4 W. H. Keesom and K. Clusius, Proc. K . Akad. Wetensch. Amsterdam, 1931,5 F. J. Allen and R. B. Moore, J . Arner. Chem. Xoc., 1931, 53, 2512, 2522;34,605; Naturwiss., 1931,19,462; A , , 1004.A., 111750 BASSETT :equilibrium of the liquid.6 The direct formation of hydrogen per-oxide from hydrogen and oxygen has been studied between 510"and 650" at pressures of 5-760 mm. and it has been shown to be aprimary product.' The yield of hydrogen peroxide (and of ammon-ium persulphate) in the electrolytic method of preparation can beconsiderably increased by using a streaming electrolyte.* Thedisplacement of arsenic, antimony, and bismuth from solutions oftheir salts by hydrogen under high pressure has been studied.9No anhydrous polyiodide of potassium can exist at 25" or above,lObut the hydrated compounds KI,,H,O and KI,,H,O, as well as thebenzene compound KI,,2C6H6, all exist a t 25".11 The polybromidesof cssium are analogous to the polyiodides in so far as tri- andtetra-bromides exist but not a pentabromide.12 Pure sodiummonoxide may be prepared by heating sodium azide with sodiumnitrite or nitrate in a nickel crucible.The reaction is smooth andeasy to control but is not applicable to potassium monoxide.Reac-tion with oxygen to form peroxide is only slow at moderate tem-peratures, but a t 100" nitric oxide reacts vigorously to form, amongother products, sodium hyponitrite, which can be obtained in a verypure state by suitable treatment. Various decompositions ofsodium hyponitrite have been studied.13T. G. Pearson and P. L. Robinson have continued their work onpolysulphides and have examined those of lithium, potassium, andrubidium.14 Rubidium and caium metaplumbates 15 and hypo-phosphites have been prepared. An account has been publishedof much further work on the curious salt-like compounds of sodiumwith certain heavy metals such as Na4Sn9 and Na,Pb, which are6 E. Cohen and W. A. T. Cohen-de Meester, Proc.K . Akad. Wetensch.Amsterdam, 1930, 33, 1003 ; A . , 1931, 294 ; A. Smits, E. L. Swart, P. Bruin,and W. M. Mazee, 2. physikal. Chem., 1931,153, 255; A., 430; J. W. Smith,J., 1931, 2573.7 R. N. Pease, J. Arner. Chem. SOC., 1930, 52, 5106; A., 320.8 E. H. Riesenfeld and A. Solovian, 2. physikal. Chem., Bodenstein Fest-band, 1931,405; A., 1248.V. V. Ipatiev, jun., M. N. Platonova, and V. S. Malinovski, Ber., 1931,64, [B], 1959; A., 1242; V. V. Ipatiev, jun., andV. I. Tichomirov, ibid.,p. 1951 ;A., 1242; V. V. Ipatiev, jun., I. R. Molkentin, and V. P. Theodorovitsch,ibid., p. 1964; A., 1243.lo Ann. Reports, 1930, 27, 67; W. D. Bancroft, G. A. Scherer, and L. P.Gould, J . Physical Chern., 1931, 35, 764; A., 580.11 N. S. Grace, J ., 1931, 594; A., 580.12 N. Rae, ibid., p. 1578; A., 921.13 5. R. Partington and C. C. Shah, ibid., p. 2071; A., 1140.1 4 Ibid., pp. 413, 1304, 1983; A . , 443, 807, 1139.l5 E. R. Sbiera, Bul. Fac. Stiinte Cernauti, 1927,1, 59; Chem. Zentr., 1931,l6 L. Hackspill and J. Weiss, Compt. rend., 1931, 192, 425; A., 443.i,1262; A., 1931, 808INORGANIC CHEMISTRY. 51soluble in liquid ammonia in the form of ammines.l' A numberof interesting compounds of the alkali metals with salicylaldehydehave been prepared by F. M. Brewer,l8 who has by their help beenable to establish the following covalency numbers : lithium 4 ;sodium 4 ; potassium, rubidium, and czesium 4 and 6.The dissociation pressures of the reaction 2CuC1, 2CuC1+ CZ,have been measured between 360" and 500".19The existence of the compounds Cu2C1,,2C0 and Cu2Br,,2CO hasbeen established by a study of the gas pressures during the actionof carbon monoxide on cuprous chloride or bromide.The iodideprobably yields a similar compound, but far more slowly. Similarsilver and gold compounds could not be obtained.20The products precipitated by the action of sulphite upon solutionsof cupric selenite depend upon the pH of the solution and mayconsist of cuprous oxide, cuprous or cupric selenide, or selenium.The conditions under which pure cuprous or cupric selenide can beobtained have been established.,l Cupric perchlorate has beenprepared as a hepta- and a di-hydrate, as well as a number ofammine derivatives.22 The conductivities of the copper (zinc ornickel) salts of various alkyl-substituted malonic acids have beenmeasured,23 and potentiometric measurements have been made withthe copper salts of various substituted aminoacetic acids.% Con-clusions are drawn as to the effects of the substituents on complex-anion formation.Silver hydride is a salt-like compound showing great analogy tolithium hydride.It can be obtained by prolonged action of atomichydrogen on silver There are two modifications of silveriodide stable below 146", one cubic (zinc blende type) and onehexagonal (wurtzite type). Another cubic variety is formed above146°.26 A number of well-crystallised salts of bivalent silver havebeen prepared in which the argentic ion has been stabilised in thefirst place by co-ordination with ad-dipyridyl and secondly by1931,154, 1, 41 ; A., 695 ; Ann.Reports, 1929,26, 42.l7 E. Zintl, J. Goubeau, W. Dullenkopf, and A. Harder, 2. physikal. Chem.,J., 1931, 361 ; A., 443.(Mlle.) A. E. Korvezee, Rec. traw. chim., 1931, 50, 505; A., 684.2o 0. H. Wagner, 8. anorg. Chem., 1931,196, 364; A., 581.21 W. Geilmann and F. W. Wrigge, 2. anorg. Chem., 1931, 197, 375; A.,22 R. Portillo and L. Alberola, Anal. Fis. Quim., 1930, 28, 1117; R. Portillo,23 D. J. G. Ives and H. L. Riley, J., 1931, 1998; A., 1126.24 H.' L. Riley and V. Gallafent, ibid., p. 2029; A., 1126.25 E . Pietsch and F. Seuferling, Natwwiss., 1931, 19, 573; A., 1019.26 R. Bloch and H. Moller, 8. physikal. Chem., 1931, 152, 245; A.,809.ibid., p.1125; A., 1931, 49.44452 BASSETT :union with strongly oxidising anions such as the nitrate, chlorate,perchlorate, or persulphate ions.27The superconductivity of gold-bismuth alloys has been shown tobe due to the definite compound Au2BLz8 Direct introduction ofgold into the aromatic nucleus has been shown to be possible by theaction of auric chloride on various aromatic compounds.29 A largenumber of derivatives of auric bromide have been prepared 30 whichshow that probably auric gold always has a co-ordination number offour and that auric bromide itself is (AuBr,), where n is at least 2.Group 11.A number of beryllium compounds have been prepared from thepurified basic acetate, and their behaviour on electrolysis in anumber of non-aqueous solvents has been examined.None of thesesolutions is suitable for the preparation of metallic beryllium.31In corrosion experiments with magnesium and magnesium alloys,a mixture of chromic acid and silver chromate has been found usefulfor removing corrosion products .32 Dehydration isotherms showthat only monohydrates and octahydrates of strontium and bariumhydroxides exist. It is doubtful whether calcium hydroxide formsany hydrate.33 The peroxides of all three metals form octahydrates,however, which react as true peroxides, liberating iodine from neutraliodide solutions and not yielding free hydrogen peroxide Thenextracted with ether.34 Several barium polysulphides have beenisolated but individual calcium compounds could not be 0btained.~5Various equilibria involved in the formation of calcium cyanamidefrom calcium cyanide or carbide have been in~estigated.~~No evidence could be found for the various compounds of halogenacids with mercuric sulphate stated to exist by previous workers,but a compound HgSO,,HgI, was obtained.37 The preparation ofHgI,[Zn(NH,) and of some similar compounds has been described.3*27 G.T. Morgan and F. H. Burstall, J., 1930, 2594; A., 1031, 234.28 W. J. he Haas and F. Jurriaanse, Naturwiss., 1931, 19, 706; A., 1224.29 M. S. Kharasch and H. S. Isbell, J . Amer. Chem. SOC., 1931, 53, 3053;30 C. S. Gibson and W. M. Colles, J., 1931, 2407; , A . , 1316,3 l H. S. Booth and G. G. Torrey, J . Physical Chem., 1931, 35, 2465, 2492;32 L. Whitby, J . SOC. Chem. Ind., 1931, 50, 83r; B., 544.33 C.Nogareda, Anal. Pis. Quim., 1931, 29, 33; A., 412; G. F. Hiittig, A.Arbes, Z. Herrmann, and C. Slonim, 2. anorg. Chem., 1931, 196, 403; A., 567.34 Idem, ibid., p. 131 ; A., 412.3 5 P. L. Robinson and W. E. Scott, J., 1931,693 ; A., 695.36 A. Cochet, 2. angew. Chem., 1931, 44, 367; H. H. Franck and H. Hei-37 M. Pai6, Compt. rend., 1930,191, 941 ; A., 1931, 50.38 M. E. Vojatsakis, Bull. SOC. chim., 1931, [iv], 49, 1029; A., 1130.A., 1172.A., 1249.mann, ibid., p. 372; A . , 807, 808INORGANIC CHEMISTRY. 53Group I I I .Solutions of B2H6 in liquid ammonia owe their electrolytic con-ductivity to the salt B2H4,2NH4. The reactions which occur duringthe electrolysis of the solution a t -75" have been in~estigated.~~The two principal reactions lead to the formation of B2H4{NH2)2and of B2H5-NH2.Several forms of aluminium hydroxide exist, and attempts havebeen made to elucidate their relation~hips.~O The precipitation ofaluminium hydroxide has been followed conductometrically.40aBy the addition of hydrogen peroxide to cold solutions of alkalialuminates, precipitates are obtained which are said to be per-aluminat esCalcium and cadmium indates, CaO,In,O, and Cd0,1n20s, havebeen prepared by calcining a t 900" nitrates mixed in the rightproportion.42The formation of a film of metal on.the glass walls of the reactiontube during the reduction of thallous or lead chloride by hydrogenis attributed to the formation of volatile thallium or lead h~drides.4~The reduction of thallic chloride by thiocyanate in aqueous solutionhas been examined.44 Lanthanum and neodymium amalgams canbe prepared by electrolysis of alcoholic chloride solutions with amercury cathode.44u Details of a simplXed method for extractinglanthanum from cerite with nitric acid have been published. Largequantities of material can be handled and a good product is saidto be 0btained.~5 Ceric selenate 46 and cerous sulphide 47 have beenprepared, and a number of double sulphates and double selenatesof neodymium have been examined.48 Many anhydrous acetatesand acid acetates of rare-earth metals have been as wellas a number of complex ceric salts of organic acids.50 Solubilities39 A.Stock, E. Wiberg, H. Martini, and A. NickIas, 2.physikal. Chem.,Bodenstein Festband, 1931, 93 ; A., 1248.40 V. Kohlschutter and W. Beutler, Helv. Chim. Acta, 1931, 14, 305, 330;A . , 581 ; H. Kraut and H. Humme, Ber., 1931,64, [ B ] , 1697; A., 1020.40a R. A. Robinson and H. T. S. Britton, J., 1931,2817.41 J. PdSek, Coll. Czech. Chem. Comm., 1930,2,653; A., 1931,50.42 L. Passerhi, Gazzetta, 1930,60, 754; A., 1931, 151.43 E. Pietsch and F. Seuferling, Naturwiss., 1931,19, 574; A., 1020.44 I. K. Taimni, J., 1931,2433; A., 1253.4Pa L. F. Audrieth, E. E. Jukkola, R. E. Meints, and B. S. Hopkins, J .4 6 R. Llord y Gamboa, Anal. Pis. Quim., 1930,28, 1145; A., 1931,51.46 J. Meyer and F. Schulz, 2. anorg. Chem., 1931,195, 127; A., 323.4 7 Picon, Compt. rend., 1931, 192,'684; A., 582.4 8 J.Meyer and (Frl.) C. Kittelmmn, 2. anorg. Chem., 1931,195,121 ; A., 321.49 A. Kotovski and H. Lehl, ibid., 109, 183; A., 1020.5 0 L. Lortie, Ann. Chim., 1930, [XI, 14,407; A., 1931, 182.Amer. Chem. SOC., 1931, 53, 1805; A., 80554 BASSETT :of lanthanum hydroxide and oxalate a t 25" have been determined,51and also of neodymium selenates over the temperature range 0-100". 52Group IV.I n the oxidation of methane by oxygen a t 360" and 100 atmospherespressure, as much as 17% of the methane burnt has been obtainedas methyl alcohol, and 0.6% as formaldehyde with no trace ofperoxide.53 The reaction is over in a few minutes and it is con-cluded that the hydroxylation theory of combustion is still to bepreferred to the peroxidation theory.A 17% yield of potassiumoxalate can be obtained by the interaction of carbon dioxide withmetallic potassium a t 230-240".5*Pure Tic, ZrC, HfC, NbC, and TaC have been prepared, and alsoTm, ZrN, TaN, and the borides of the same metals. Details of thepreparation and properties of the compounds are given.55Disilicon hexafluoride, Si,F6, has been prepared by the interactionof the hexachloride with anhydrous zinc fluoride. It is instantlyhydrolysed by moisture.56 The formation of monosilicic acid andits polymerisation have been ~tudied,~' and a number of complexcyclohexanol derivatives of silicic acids have been prepared byinteraction of cycZohexano1 and silicon tetra~hloride.~~Dehydration of hydrated stannous chloride by acetic anhydrideis a convenient way of preparing the anhydrous compound.59Stannites and thio-oxystannites of calcium, strontium, and bariumhave been made by combination of stannous oxide or sulphide a thigh temperatures with the alkaline earth.60There are only two polymorphic forms of lead monoxide, the redand the yellow.Black forms obtained from solution or by theaction of heat or light on the red or the yellow form owe their colourto the presence of metallic lead.61 Two types of lead dioxide aresaid to exist.6251 I. M. Kolthoff and (Miss) R. Elmquist, J. Amer. Chem. SOC., 1931, 53,1217; A., 677.52 J. A. N. Friend, J., 1931, 1802; A., 1020.53 W. A. Bone, Nature, 1931, 127,481; 128, 188; A., 598, 1030.54 31. Lemarchands and H. L. Roman, Compt. rend., 1931,192,1381 ; A., 921.55 A.Agte, K. Moers, Heyne, and K. Becker, 2. anorg. Chem., 1931, 198,56 W. C. Schumb and E. L. Gamble, J. Amer. Chem. SOC., 1931, 53, 3191 ;5 7 H. Kraut, Ber., 1931, 64, [B], 1709; A., 1021.5 8 R. Signer and H. Gross, Annalen, 1931, 488, 56; A., 1021.59 H. Stephen, J., 1930, 2786; A., 1931, 182.6 o S. Tamaru and H. Sakurai, 2. anorg. Chem., 1931,195,24; S. Tamaru andO1 M. P. Applebey and H. M. Powell, J . , 1931, 2821.62 E. J. Rode, J . Rzcss. Phys. Chem. SOC., 1930, 62, 1419; A., 1931, 61.233; A., 921.A., 1140.Y. Tanaka, ibid., p. 35; A., 320, 321INORGANIC CHEMISTRY. 55The electrolytic formation of amalgams of titanium, uranium, andvanadium has been examined, and also some of the properties of theamalgams so obtained.63 Cobalt and zinc orthotitanates have beenprepared and added to the spinel gr0up.~4 The extraction ofgermanium from germanite has been described.65 Methods havebeen given for preparing germanic nitride,G6 sulphate, and oxychloride(Ge20C1,),67 ai:d of a number of double compounds of germaniumdichloride and tetrachloride with organic bases.68 Work ongermanium imide and germanomolybdic acid reported last year hasbeen confirmed by other workers.69Zirconium dibromide has been prepared as a black powder whichreacts violently with water, liberating hydrogen.It is obtaineda t 350" by the reaction 2ZrBr,+ ZrBra + ZrBr2, whilst ZrBr,is prepared by reduction of ZrBra with aluminium in an atmosphereof hydrogen a t 450". It is a bluish-black powder giving with watera rapidly fading yellow solution from which hydrogen is liberatedand which has powerful reducing properties.70 Normal zirconiumoxalate can be precipitated from methyl-alcoholic solution, and alsothe aniline derivative (PhN),Zr.71 Zirconium and hafnium sulphatesare very difficult to prepare free from excess of ~ulphate.'~Group v.The properties of nitrogen trifluoride have been examined andseveral intermediate stages in its formation have been isolated,including NH,F and NHF2 and a yellow compound which is thoughtto be NF,.These are all gases at ordinary temperature andpressure.73 Nitrogen tri-iodide also has been isolated by the actionof dry ammonia on various iododibromides. 74The action of nitric oxide on alkaline hydroxides 75 and upon63 R.Groves and A. S. Russell, J., 1931, 2805 ; A., 1377.64 L. Passerhi, Guzzettu, 1930, 60, 957; A., 1931, 289.6 5 W. I. Patnode and R. W. Work, Ind. Eng. Chem., 1931,23,204; B., 495.66 W. C. Johnson, J. Arner. Chem. SOC., 1930,52, 5160; A., 1931, 322.6 7 R. Schwarz, P. W. Schenk, and H. Giese, Ber., 1931, 64, [B], 362; A.,446.A. Tchakirian, Cornpt. rend., 1931, 192, 233; A., 322; J. S . Thomas andW. W. Southwood, J., 1931, 2083; A., 1140.69 Ann. Reports, 1930, 27, 65; J. S. Thomas and W. Pugh, J., 1931, 60;C. G. Grosscup, J. Amer. c'hem. SOC., 1930,52, 6154; A., 1931,322.7 0 R. C. Young, J. Arner. Chem. SOC., 1931, 53, 2148; A., 922.71 H. S. Gable, ibid., 1931, 53, 1276, 1612; A., 696.7 2 G. von Hevesy and E. Cremer, 2.anorg. Chem., 1931,195, 339; A., 322.73 0. Ruff, W. Menzel, Hecht, E. Hanke, L. Staub, H. Wallauer,. andE. Ascher, ibid., 197, 273; 0. Ruff and E. Hanke, ibid., p. 395; 0. Ruff and(Frl.) L. Staub, ibid., 198, 32; A., 696, 809.74 H. W. Cremer and D. R. Duncan, J., 1930,2750; A., 1931, 182.76 E. Barnes, J., 1931, 2605 ; A., 137956 BASSETT :various reducing agents 76 has been examined. Various reactionsof (HSN), have been studied, and the product obtained by theaction of chlorine upon N4S4 is shown to have the formula (NSCl),and is considered to be N<sc1:N>SC1.77 Variations in the densityof red phosphorus dependent upon the temperature and pressure atwhich it has been produced from white phosphorus have beenexamined. 78Direct union of the elements yields phosphides and arsenides ofniobium, tantalum, molybdenum, and tungsten,59 and variousphosphides result from the action of hypophosphites on acid oralkaline solutions of nickel or cobalt salts.80The compounds AlCl,,PH,, AlBr3,PH,, and AlI,,PH, are allreadily formed and can be sublimed. Beryllium halides do notcombine with phosphine.81Addition compounds of phosphorus pentachloride and antimonypentachloride with pyridine have been reported.82Nickel arsenide, Ni3As2, results from the prolonged action offhely divided 'nickel, reduced at a low temperature, upon a hotsolution of arsenious chloride.8,Antimony bromodi-iodide, SbBrI,, results from the action ofbromine upon ethyldi-iodostibine, although chlorine yields only thetri-iodide. ** X-Ray examination of the system bismuth-iodineshows that only the tri-iodide exists and no s~b-iodide.~~ There aredefinite indications of the existence of a compound Bi,03,3H,0.s6A large number of internally complex organic acid salts of bismuthand of ter- and quinque-valent antimony and arsenic have beendescribed.87 From a study of the isomorphous relationships of itssalts with those of several other metals, it is concluded that polonium76 H.Gehlen, Ber., 1931, 64, [BJ, 1267; M. L. Nichols and C. W. Morse, J .Physical Chem., 1931, 35, 1239; H. B. Dunniclifl, S. Mohammad, and J.Kishen, ibid., p. 1721 ; A . , 922.77 A. Meuwsen and H. Holch, Ber., 1931, 64, [B], 2301 ; A. Meuwsen, ibid.,p. 2311 ; A., 1254.7 8 V. N.Ipatiev, A. Frost, and A. V. Vedenski, Bull. SOC. chim., 1931, Liv],49,670; A., 898.79 E. Heinerth and W. Biltz, 2. anorg. Chem., 1931,198, 168; A., 809.8o R. Scholder and H. Heckel, ibid., p. 329; A., 922.81 R. Holtze and F. Meyer, ibid., 197, 93 ; A., 583.82 J. C. HuttonandH. W. Webb, J., 1931, 1518; A., 922.83 G. Arrivaut, Compt. rend., 1931, 192, 1238; A., 810.8 5 V. Caglioti, Qazzetta, 1930, 60, 933 ; A., 1931, 323.86 G. F. Huttig, T. Tsugi, and B. Steiner, 2. anorg. Chern., 1931, 200, 74;87 A. Rosenheim, I. Baruttschisky, W. Bulgrin, W. Plato, and G. Ebert,SCl'NR. E. D. Clark, J., 1930, 2737; A . , 1931, 183.A., 1235.ibid., p. 173; A., 1254INORUANIC CHEMISTRY. 57can have valencies of three and four.88 An elaborate study has beenmade of the electrolytic reduction of vanadium through all thestages from quinque- to bi-valent, various kinds of electrodes behg~ s e d .8 ~ The exact procedure in the electrolytic reduction of vanadicacid for the satisfactory isolation of crystalline vanadous sulphateheptahydrate has been worked out, and details given of the prepar-ation of the relatively stable ammonium, potassium, and rubidiumvanadous sulphates. Vanadous salts of other acids are less stableand are difficult to prepare.90The interaction of niobium and tantalum pentoxides with theoxides of various metals has been studied in the solid state, andindications have been obtained of the formation of a number of newniobates and tantalates.91 In an account of the isolation of proto-actinium in the industrial treatment of pitchblende, it is shownthat about 85% of the element present in the mineral dissolves withthe uranium during the digestion with sulphuric acid.This wasrecovered by adsorption on a gel of tantalic acid.92Group V I .The formula H2S,6H20 has been deduced for the hydrate ofhydrogen sulphideg3 It has been suggested that thiosulphonic acidis the primary product of the interaction of hydrogen sulphide andsulphur dioxide in presence of mercury and absence of water.94The effect of catalysts on the combination of sulphur monochloridewith chlorine has been considered, as well as several peculiarities ofthe reaction.95It has been shown that colloidal sulphur prepared from sodiumthiosulphate is the sodium salt of a sulphur-polythionate complex,and that there is a definite equilibrium in the sol between the poly-thionate which is free and that which is bound, ie., attached to thecomplex.As the sol ages, more and more polythionate becomesfree. The behaviour of the sol towards coagulants is quantitativelydetermined by the amount of bound p0lythionate.~6Selenium dioxide combines directly with hydrogen chloride orM. Guillot, J. Chirn. physique, 1931, 28, 92; A., 697.F. Foerster and F. Bottcher, 2. physikal. Chem., 1930, 151, 321; A.,J. Meyer and (Frl.) M. Aulich, 2. unorg. Chern., 1930,194,278; A., 1931,1931, 178.178.91 W. Jander and H. Frey, ibid., 1931,196, 321 ; A., 447.O2 F. Reymond, J . Chirn. physique, 1931,28,409; A., 1255.O3 (Mlle.) A.Korvezee and F. E. C . Scheffer, Rec. trav. chim., 1931, 50, 256;94 B. S. Rao andM. R. A. Rao, Nature, 1931,128,413; A., 1134.95 T. M. Lowry and G. Jessop, J., 1931, 323; A., 438.96 H. Bassett and R. G. Durrant, ibid., p. 2919.A., 58358 BASSETT :bromide.g7 A number of complex selenocyanammines have beenpre~ared.~s Several papers have been published which deal withthe passivity of chromium.99A large number of very complex ammines of tervalent molybdenumhave been described,l and so have complex cyanides and thio-cyanates of quadrivalent molybdenum and complex oxalates andhydroxylamine * derivatives of sexavalent molybdenum. A numberof complex molybdenum sulphates have also been investigated.5Molybdenum-blue is considered to be M00,,4MoO,,xH~0.~Several oxy-salts (permolybdates) result from the action of hydrogenperoxide upon ammonium molybdate.7 The precipitates formedby the interaction of sodium molybdates with various metal saltsmay consist of normal molybdate, basic molybdate, molybdic acid,or various mixtures, according to circumstances.8 All the pre-cipitates obtained by means of sodium tungstates are essentiallybasic in nature.9 5Na,0,12W03,28H,0 was obtained by the actionof formic acid upon sodium tungstate. Similar potassium andbarium salts were also prepared.10 Apparently W,O, does notexist, and only WO, and W,Oll of the lower oxides of tungsten arestable. l1 Several complex quinquevalent molybdenum salts ofpreviously known types have been recorded.12Group V I I .Improvements in detail of some importance in the preparation ofA number of the physical constantsO 7 T.W. Parker and P. L. Robinson, J., 1931, 1314; A., 923.O 8 G. Spacu and C. G. Macarovici, Bul. SOC. Stiinte Cluj, 1930, 5, 169;Chem. Zentr., 1930, ii, 708; A., 1931, 183.O9 E. Miiller and 0. Essin, 2. Elektrochem., 1930, 36, 963 ; E. Miilk and K.Schwabe, ibid., 1931, 37, 185; W. J. Miiller, ibid., p. 328; A., 1931, 173, 571,915.A. Rosenhehn, G. Abel, and R. Levy, 2. anorg. Chem., 1931,197,189; A.,697.G. A. Barbieri, Atti R. Accad. Lincei, 1930, [vi], 12,55; 13, 376; A., 183,1255.H. M. Spittle and W. Wardlaw, J . , 1931, 1748; A., 1035.W. F. Jak6b and B. Jezowska, Rocz. Chem., 1931,11, 229; A., 923.F. H. Nicholls, H. Saenger, and W.Wardlaw, J., 1931, 1443; A., 923.C. R. ZinzadzB, Bull. SOC. chim., 1931, [iv], 49,872; A., 1021. ' V. Caglioti, Gazzetta, 1931, 61, 257; A., 923.* H. T. S. Britton and W. L. German, J . , 1931, 1429; A., 911.lo R. H. Vallance, ibid., p. 1421 ; A., 923.11 E. Tarjh, Naturwiss., 1931, 19, 166; A., 447; J. A. M. van Liempt,l2 A. Paulssen von Beck, 2. anorg. Chem., 1931,196, 85 ; A., 447.l3 L. M. Dennis, J. M. Veeder, and E. G. Rochow, J . Amer. Chem. Soc., 1931,fluorine have been recorded.13Idem, ibid., p. 709; A., 697.Rec. trav. chirn., 1931, 50, 343; A., 583.53, 3263; A., 1248INORGANIC CHEMISTRY. 59of fluorine monoxide have been measured, as well as its chemicalbehaviour towards numerous elements and compounds. It iswithout action on dry glass and is non-explosive, but, physiologically,it is more dangerous than fluorine.14A rapid and economical method of preparing large quantities ofiodine trichloride 15 has been described, and a number of newpolyhalides have been prepared.16 Solubilities and dissociationpressures of many of the latter have been measured, and it has beenshown that stability of the anion is favoured by symmetry and bythe presence of one, but not more than one, iodine atom.17 Isobarsof the thermal decomposition of iodic acid show that H1308 is formedat 70" and 120, a t 200".When heated in air, 120, begins todecompose a t 275O.18Observations made on the transformation of pink manganesesulphide into the green form do not altogether agree with thosereported last year.l9 A phosphate of tervalent manganese,NH4H,Mn1rI(P04)2, has been recorded.20 Conflicting views havebeen put forward as to the existence of definite hydrates ofmanganese dioxide.21There has been great activity in connexion with rhenium sincepotassium per-rhenate became available commercially.22 Much ofthe arc spectrum of rhenium has been ma~ped,~3 and many physicalconstants of the metal have been measured.The melting point ofrhenium is very high, being 3440" 50" Abs.= The fusion diagramof the system tungsten-rhenium has been examined.25 Much workl4 0. Ruff and W. Menzel, Z . anorg. Chem., 1931,198,39; A . , 810.l5 E. C. Truesdale and F. C. Beyer, J. Amer. Chem. SOC., 1931,53,164; A.,l6 H. W. Cremer and D. R. Duncan, J., 1931, 1857; A ., 1022.l7 Idem, ibid., p. 2243 ; A., 1236.l8 E. Moles and A. Perez-Vitoria, Z . physikal. Chem., Bodenstein Festband,lo Ann. Reports, 1930,27, 73 ; H. B. Weiser and W. 0. Milligan, J. Physical2o A. Yakimach, Compt. rend., 1931,192, 1652; A., 1022.21 A. Simon and F. Feher, KoZZoid-Z., 1931, 54, 49; A., 306; W. Biltz and0. Rahlfs, Nach. Ges. Wiss. Gcittingen, 1930, 189; Chem. Zentr., 1931, i, 46;A., 683.324.1931, 583 ; A., 1225.Chem., 1931,35,2330; A., 1140.22 Ann. Reports, 1930,27, 73.H. Schober and J. Birke, Naturwiss., 1931,19,211; A . , 404; W. Meidinger,2. Physik, 1931,68, 331; A., 540; W. F. Meggers, BUT. Stand. J . Res., 1931,6, 1027; A., 993.24 C. Agte, H. Alterthum, K. Becker, G. Heyne, and K. Moers, Naturwiss.,1931, 19, 108; 2.anorg. Chem., 1931, 196, 129; A., 288, 448; K. Moeller,Naturwiss., 1931, 19, 575; A., 1001.25 K. Becker and K. Moers, Metallwirt., 1930, 9, 1063; Chem. Zeniir.,1931, i, 750; A., 67660 BASSETT :on the analytical chemistry of the element has been published duringthe past year 26 and summaries of its chemistry and geochemistryhave appeared.27Rhenium tetrachloride and a number of rhenichlorides have beenprepared.28 Black ReOz and purplish-red Re20, can be obtainedby suitable reduction methods from per-rhenic acid.29 Copper,nickel, and cobalt per-rhenates and various ammines of thesecompounds have been de~cribed.~~ Re,S, is precipitated fromaqueous solutions of potassium per-rhenate by either hydrogensulphide or sodium thiosulphate.On heating it yields ReS,. Thecorresponding selenides were also prepared.31 Thio-derivatives ofper-rhenic acid have been recorded,32 but it is doubtful whether theyreally e ~ i s t . ~ 3 Densities of solutions of per-rhenic acid have beenmeasured34 and so has the heat of formation of ReS2.35Group YIII.The behaviour on heating of hydrated ferrous and ferric oxideshas been described,36 and also the reduction by hydrogen of ferricoxide.37 Crystalline Fe203,4H,0 has been obtained by slowhydrolysis of a boiling dilute solution of ferric ethoxide in absoluteA number of reactions of the iron carbonyls have been described,including the formation of Fe(CO),H2, which is a volatile yellow oil,by the action of bases on iron pentacarb~nyl.~~ Further experi-ments with iron nitrosyls are described which are considered to26 C.Agte et al., 2. anorg. Chem., 1931, 196, 129; A., 448; F. Krauss andH. Steinfeld, ibid., 197, 52; A . , 589; W. Geihann, F. Weibke, F. W. Wrigge,and K. Briinger, ibid., 195, 289; 199, 65, 77, 120, 347; A., 328, 1025, 1143.27 I. and W. Noddack, 2. angew. Chem., 1931, 44, 215; 2. physikal. Chem.,1931, 154, 207 ; A., 583, 707.28 E. Enk, Ber., 1931,64, [ B ] , 791 ; A., 810; H. V. A. Briscoe, P. L. Robin-son, and E. M. Stoddart, J., 1931,2263 ; A . , 1255.z9 Idem, ibid., p. 666; A . , 584; H. V. A. Briscoe, P. L. Robinson, and A. J.Rudge, ibid., p. 3087.30 Idem, ibid., p. 2211; A., 1139.31 H. V. A. Briscoe, P. L. Robinson, and E. M. Stoddart, ibid., p. 1439; A .,32 W. Feit, 2. angew. Chem., 1931, 44, 6 5 ; 2. anorg. Chew&., 1031, 199, 263;33 H. V. A. Briscoe, P. L. Robinson, and E. M. Stoddart, J., 1931,2976.35 I. R. Juza and W. Biltz, 2. Elektrochem., 1931, 37, 498; A . , 1128.36 G. F. Huttig and H. Moldner, Z. anorg. Chern., 1931,196, 177; A , , 432;37 E. J. Rode, ibid., p. 1453; A., 1931, 53.38 R. A. Thiessen and R. Koppen, Z. anorg. Chem., 1931, 200, 18; A . , 1255.39 W. Hieber and F. Leutert, Naturwiss., 1931,19, 360; A . , 810; W. Hieberalcoh01.38924.A . , 924, 1255.W. Feit, 2. anorg. Chem., 1931,199,271; A., 1223.E. J. Rode, J . Russ. Phys. Chem. SOC., 1930,62, 1443; A . , 1931, 53.and H. Vetter, Ber., 1931, 64, [B], 2340; A . 1266INORGANIC CHEMISTRY. 61oppose the view that certain of them-such as Fe(S*CS*OEt),(NO),-contain univalent iron.40 The red colour of the alkali ferrithio-cyanates and of ferric thiocyanate itself is attributed to the ionFe(CNS),”’ and the molecular weight of ferric thiocyanate in benzeneand ether is found to correspond with the formula Fe[Fe(CNS)6].41Ilmenite and ferrous orthotitanate have been prepared by heatingtogether at 900” suitable mixtures of titanium dioxide and ferrousoxalate.Ferric orthotitanate was similarly prepared, the indi-viduality of the three compounds being confirmed by an X-rayanalysis.42Persulphatopentamminocobaltic sulphate, formulated as[CO(SO~)~(NH~)~](SO~)II,H~O, has been prepared, and the conclusionhas been drawn that persulphuric acid is HSO, and not H2S,08.43Several t e t ramminoco baltic complexes containing t hiosulphate aresaid to have been 0btained.~4Various nickel dimethylglyoxime salts and related compoundshave been prepared in an endeavour to find an explanation of thedifferent behaviour of bivalent cobalt, nickel, and copper towardsdimethylglyoxime.The main difference is attributed to thetendency of nickel t o remain co-ordinatively quadrivalent whilecobalt tends to be co-ordinatively sexavalent .45A number of tris-ad-dipyridyl nickelous salts have been prepared,and the resolution of the chloride has been effected with the helpof ammonium &tartrate,. The active forms are rapidly racemisedin aqueous s0lutions.~6 The effect of the temperature to which ithas been heated on the solubility of nickel oxide in sulphuric acidhas been examined in connexion with the extraction of copper oxidefrom roasted nickel-copperThe arsenides RuAs2, RhAs,, PdAs,, IrAs2, and PtAs, were pre-pared by heating a mixture of the chloride with excess of arsenicin a current of hydrogen.48A number of complex derivatives of tervalent ruthenium 49 and4O H. Reihlen, E.Elben, and J. Everet, Annalen, 1931, 485, 43; A . , 449.41 H. I. Schlesinger and H. B. Van Valkenburgh, J . Amer. Chem. SOC., 1931,42 B. Pesce, Gazzetta, 1931, 61, 107; A., 584.43 C . Duval and (Mme.) Duval, Compt. rend., 1930, 191, 843; A., 1931, 53.44 P. B. Sarkar and T. Das-Gupta, J. Indian Chem. Soc., 1930, 7, 835; A.,4 5 E. Thilu and H. Heilborn, Ber., 1931,64, [ B ] , 1441 ; A., 938.46 G.T. Morgan and F. H. Burstall, Nature, 1931,127, 854; J., 1931, 2213;47 M. Prasad and M. G. Tendulkar, J., 1931, 1403, 1407; A., 924.4 8 L. Wohler and R. F. A. Ewald, 2. anorg. Chem., 1931,199, 5 7 ; A., 1022.4s R. Charonnat, Compt. rend., 1930,191, 1453; A., 1931, 184; Ann. Chirrz.,53, 1212; A., 670.1931, 184.A . , 895, 1168.1931, [XI, 16, 6 ; A., 126662 BASSETT :rhodium 50 have been reported in all of which the ruthenium andrhodium have a co-ordination number of six. The action of variousoxidising agents on OsS, has been examined.51 The optical activitiesof a number of tetrammine salts of bivalent platinum and palladiumshow that the four linkings cannot lie in a plane.52 On the otherhand, Werner’s views as to the structures of the two forms ofPt(NH3),C12 are supposed to be confirmed by the behaviour of thetwo compounds with oxalic acid.53By the interaction of very dilute solutions of disodium hydrogenphosphate and ammonium chloroplatinate a t room temperature, thecompoundsare formed.This has some bearing on the accurate analysis of sometypes of silicates, for there is a possibility of the above platinumcompounds, formed from platinum dissolved from the apparatus,being precipitated with magnesium ammonium phosphate.%Definite equilibria of the type, PtBr,” + 6C1’ Z PtC16” +6Br’,exist and light accelerates attainment of equilibrium in aqueoussolution. The concentration of chloride ion must be 660 times thatof bromide ion for the equilibrium to be shifted 99% from left toright, while the concentration of bromide ion must be 25 x lo3that of iodide ion to cause a like shift in the reaction PtI,” + 6Br‘PtBr,” + 61’.These figures indicate the relative order inwhich the halogen ions tend to co-ordinate with platin~m.~5[Pt(NH,),C1(NH,)](H2P04), and [Pt(NH3)4C1(NH,)](H2PO,)OHSystems and Equilibria.Co-Cr s6; Cr203-SiO, 5 7 ; NaI + KCl --j KI + NaCl 5 8 ;NaN03-Na2S04-MgC12-H20 59 ; strontium amalgams ; Fe-P-G. A. Barbieri, Atti R. Accad. Lincei, 1931, [vi], 13, 433; A., 1141.Si 61 , - Th(NO,),-Et,O-H,O 62 ; U02(N03)2-Et20-H20 63 ; Li20-51 E. Fritzmann and E. M. Zuhn, 2. anorg. Chem., 1931,199,374; A., 1141.52 H. Reihlen and W. Hub, Naturwiss., 1931,19,442; Annalen, 1931, 489,53 A. A. Griinberg, Helv. Chim.Acta, 1931, 14, 455; A . , 698.54 B. E. Dixon, J., 1931, 2306; A . , 1256.6 5 H. I. Schlesinger and R. E. Palmateer, J. Amer. Chem. SOC., 1930, 52,5 G F. Wever and U. Haschimoto, Mitt. Kaiser- Wilh. Inst. Eisenforsch., 1929,5 7 E. N. Bunting, Bur. Stand. J . Res., 1930, 5, 325; A., 1931, 41.6 8 N. M. Waksberg, J. Rum. Phys. Chem. SOC., 1930,62, 1259; A., 1931,41.69 G. Leimbach, Caliche, 1929-30, 11, 340, 386, 428; A., 1931, 41.6 o G. Devoto and E. Recchia, Qazzetta, 1930, 60, 688; A., 158.61 W. Hummitzsch and F. Sauerwald, 2. anwg. Chem., 1930,194, 113; A.,62 P. Misciattelli, Gazzetta, 1930, 60, 533; A . , 1931, 159.63 Idem, &id., p. 839; A , , 1931, 160.42; A., 924, 1167.4316; A., 1931,54.11, 293 ; A., 1931, 41.1931, 158INORGANIC CHEMISTRY.63SiO,64 ; HgCl,(HgBr,)-HgS0,65 ; carbides of high m. p.'? Na,SiO,-Fe,O,-SiO, 67 ; [Co(NH,),Cl]Cl, + 2HBr t [CO(NH,)SC~IB~, 4-2HC168 ; Li-Cu 69 ; Bi-Se 70 ; .Al-Mn ; CU-Mn ; F e M n 71 ;CaO-Si0,-H,O 72 ; MgO-FeO-Fe,O, 73 ; KNO,-Ca(NO,),-H,O 74 ;(NH,),S 0,-MnS0,-H,O, T1,SO4-MnS O,-H,O, Rb,S 04-~so4-H,O 75 ; Ba(CNS),-NaCNS-H,O and Ba(CNS),-KCNS-H,O 76 ;Fe-GSi 77 ; Li-Ag 78 ; I,-H,O 79 ; Zr0,-Be0 ; KN03-Ca(NO,), 8 l ; RbN03-RbC182 ; NaHC0,-Na,SO,-H,O a3 ; Cd-Ag 84 ; NaN03-NaI03-H,0 s5 ; Mg(I0,)2-Mg(N0,)2-H20 86 ;Ag,SO, + Tl,Cl, S Tl,SO, + Ag2C1287 ; W-Re s8; CoC1,-Co(NO,),-H,O 89 ; (CH,) 6N4-MgC12(CaC1,)-H,0 ; KmS-Hg(CNS),-H,O 91; MgSO, + 2KNO, Mg(NO,), + K,S0,91a;64 F. C. Kracek, J . Physical Chem., 1930,34,2641; A., 1931, 169.~ 3 5 M.Pai6, Compt. rend., 1930,191, 1337; A., 1931, 169.66 C. Agte and H. Alterthum, 2. tech. Physik, 1930,11, 182; A., 1931, 170.67 N. L. Bowen, J. E. Schairer, and H. W. V. Willems, Amer. J . Sci., 1930,68 A. Benrath and H. Pitzler, 2. anorg. Chem., 1930,194,358 ; A., 1931, 170.69 S. Pastorello, Gazzetta, 1930,60, 988; A., 1931, 296.7 O N. Parravano and V. Caglioti, ibid., p. 923 ; A., 1931, 296.71 T. Ishiwara, Sci. Rep. TGhoku Imp. Univ., 1930,19, 499; A,, 1931, 296.7 2 A. Vigfusson, Amer. J . Sci., 1931, [v], 21, 67; A., 310.'3 H. S. Roberts and H. E. Merwin, ibid., p. 145; A., 310.74 M. A. Hamid and R. Das, J . Indian Chem. SOC., 1930, 7, 881; A., 1931,7 5 A. Benrath, 2. anorg. Chem., 1931, 195,'247; A., 310.7 8 V.J. Occleshaw, J., 1931, 65; A., 310.7 7 A.7 8 S. Pastorello, Gazzetta, 1931, 61,47; A., 418.7 9 F. C. Kracek, J. Physical Chem., 1931, 35,417 ; A., 418.[v], 20, 405; A., 1931, 170.310.and F. Pobogil, Coll. Czech. Chem. Comm., 1931, 3, 61; A., 418.0. Ruff, I?. Ebert, and H. von Wartenberg, 2. anorg. Chem., 1931, 196,A. P. Rostkovski, J. Russ. Phys. Chem. SOC., 1930, 62, 2055; A., 1931,335 ; A., 431.431.82 Idem, ibid., p. 2067; A., 1931, 432.83 S. 2. Makarov and N. M. Waksberg, ibid., p. 1863; A., 1931, 432.84 P. J. Durrant, Inst. Metals, Mar. 1931; A., 556.s5 E. Cornec and A. Spack, Bull. SOC. chim., 1931, [iv], 49, 582; A,, 800;86 A. E. Hill and S. Moskowitz, ibid., p. 941 ; A., 568.s7 S. I. Sokolov, J . Russ. Phys. Chem. SOC., 1930, 62, 2329; A., 1931,K.Becker and K. Moers, Metallwirt., 1930, 9, 1063; Chem. Zentr.,A. E. Hill and J. E. Donovan, J . Amer. Chem. SOC., 1931, 53, 934; A., 568.668.1931, i, 750; A., 1931, 676.89 V. Cuvelier, Natuurwetensch. Tijds., 1931, 13, 75; A., 684.Dl C. W. Mason and W. D. Forgeng, J. Physical Chem., 1931, 35, 1123 ; A .,O l a A. Benrath and A. Sichelschmidt, 2. anorg. Chem., 1931,197, 113; A.,V. Evrard, ibid., p. 105; A., 684.684.68564 BASSETT :LiBr03-H20 O2 ; SO,-NH,I (or alkali iodide) 93 ; PbO-H,O 94 ;Fe,03-CuO-S03 95 ; Cu-Sn 96 ; Ca-Na 97 ; SrC1,-FeCl,, SrC1,-CoCI,,ZnCl,-FeCl,, ZnCl,-CoCl, 98 ; Li,Br,-MgBr, 99 ; BaS0,-H,S04-H,O ; Al,03-Cr203-Mg0 ; K,SO4--H2SO4-H2O 3 ; Na,S04-Na,Cr,O,-H,O ; K,SO,-K,Cr,O,-H,O ; NaNO,(KNO,)-NaNO,(KNO,)-H,O ; NaNO,(KNO,)-NaCl(KC1)-H,O 6 ;Na,Cr,O,-NH,Cl-H,O ; Fe-S-C ; Fe-N ; Fe-G-V 10 ; AI-Ag 11 ;Cr-C l2 ; Cr,03-A1,0, l3 ; CaO-Fe20, l4 ; Pb1,-AgI 15 ; ZnO-HN0,-H,O l6 ; PbO-N,05-H,0 l7 ; K,O-CaO-SiO, l 8 ; K2S04-MgS04--NaC1-H,0 l9 ; Alsi 2O ; Ca-Bi 21 ; Fe-GW 22 ; Ag,O-B2 J.P. Simmons and W. F. Waldeck, J . Amer. Chem. SOC., 1031, 53, 1725;O3 H. W. Foote and J. Fleischer, ibid., p. 1752; A., 799.Q p G. F. Huttig and B. Steiner, 2. unorg. Chem., 1931,197, 257; A., 799.O 5 G. Tunell and E. Posnjak, J . Physical Chem., 1931, 35, 929; A., 800.O6 M. Hamasumi and 5. Nishigori, J . Study Met., 1930, 7, 535; A., 900.O 7 E. Rinck, Compt. rend., 1931,192,1378; A., 900.O a A. Ferrari and A. Inganni, Atti R. Accad. Lincei, 1930, [vi], 12, 668 ; A.,O9 A.Ferrari and C. Colla, ibid., 1931, [vi], 13, 78; A., 901.A., 799.1931, 901.N. R. Trenner and H. A. Taylor, J . Physical Chem., 1931, 35, 1336; A.,K. J. A. Bonthron and R. Durrer, 2. anorg. Chem., 1931, 198, 141; A.,A. V. Babaeva, Trans. Inst. Pure Chem. Reag., 1931,11, 114; A., 911.A. V. Rakovski and E. A. Nikitina, ibid., p. 5; A., 911.ti A. V. Rakovaki and A. V. Babaeva, ibid., p. 15; A., 912.6 A.V.RakovskiandD.S.Slavina,ibid.,p.20; A.,912.7 J. Gerasimov, ibid., p. 34; A., 912.R. Vogel and G. Ritzau, Arch. Eisenhuttenw., 1930-1, 4, 549; Stahl u.901.911.Eisen, 1931, 51, 793; B., 1931, 807.0 W. Koster, ibid., pp. 537, 740; B., 807.10 R. Vogel and E. Martin, ibid., pp. 487,715; B., 807; H. Hougardy, ibid.,pp. 497, 592 ; B., 808; M.8ya, Sci. Rep. T6hoku Imp. Uniw., 1930, 19, 449 ;A., 1931, 297.11 E. Crepaz, Atti I I I . Cong. Nax. Chim., 1929, 371; Chem. Zentr., 1931, i,2158; A., 1931, 1005; T . P. Hoar and R. K. Rowntree, Inst. Metals, Mar.1931 ; A,, 556.12 K. Hatsuta, J . Study Met., 1931, 8, 81 ; A., 1005.13 E. N. Bunting, Bur. Stand. J . Res., 1931, 6, 946; A., 1010.14 J. Konarzewski, Rocz. Chem., 1931, 11, 516; A., 1010.l5 F. E. E. Germann and C. F. Metz, J . Physical Chem., 1931,35, 1944; A.,16 H. G. Denham and D. A. Dick, J., 1931, 1753; A., 1011.17 H, G. Denham and J. 0. Kidson, ibid., p. 1757; A., 1011.18 G. W. Morey, F. C. Kracek, and N. L. Bowen, J . SOC. Glass Tech., 1931,l9 D. Langauer, Rocz. Chem., 1931,11, 477; A., 1011.20 V. Fuss., 2. Metallk., 1931, 23, 231 ; B., 929.21 E. Kurzyniec, Bull. Acad. Polonaise, 1931, [A], 31; A., 1118.1010.15, 57'11; A., 1011INORGAXIG CHEMISTRY. 65H2023 ; KRe0,-H,024 ; AgN0,-Ca(N0,)2[Ba(N0,)2] 25 ; CU(C~O~)~-H20 and CU(C~O~),-HC~O~-H~O~~ ; Cr-Fe 27 ; F e S n 28 ; Al-Cr 29 ;Ag-Bi(Sb or As) 30 ; Au-Sb, Ag-Sn31; Cu-Mg 32 ; FeO-MnO ; MnS-MnO ; MnS-MnSiO, ; MnS-Fe,Si0433 ; C O C ~ , - Z ~ C ~ , ~ ~ ; Li,S04-AI2(SO4),-H,O S5 ; A~-CU,O.~~H. BASSETT.22 S. Takeda, Tech. Rep. Tdhoku Imp. Univ., 1931,10,42; A., 1118.23 R. P. P. Mathur and N. R. Dhar, 2. a w g . Chem., 1931, 199, 387; A.,24 N. A. Pushin and D. KovaE, 2. anorg. Chem., 1931,199,369; A., 1119.25 A. P. Palkin, Bull. Univ. Asie centrale, 1929,18, 77; A., 1931, 1128.28 C. Smeets, Natuurwetensch. Tijds., 1931, 13, 247; A,, 1128.27 F. Adcock, G. D. Preston, and C. E. Webb, Iron and Steel Inst., Sept.28 C. A. Edwards and A. Preece, ibid. ; B., 1053.29 M. Goto and G. Dogane, Nippon Kogyokwaishi, 1927, No. 512, 931 ; A.,30 S. J. Broderick and W. F. Ehret, J. Physical Chem., 1931, 35, 2627; A.,31 0. Nial, A. Almin, and A. Westgren, 2. physikal. Chem., 1931, [B], 14,81;a2 W. R. D. Jones, Inst. Metals, Sept. 1931 ; Advance copy; A., 1224.33 J. H. Andrew, W. R. Maddocks, D. Howat, and E. A. Fowler, Iron and34 H. Bassett and W. L. Bedwell, J., 1931, 2479; A., 1235.8s J. P. Sanders and J. T. Dobbins, J. Physical Chem., 1931, 35, 3086; A.,86 J. A. A. Leroux and K. W. Frohlich, 2. Metallk., 1931, 23, 250 ; A., 1235.11 19.1931, Advance copy; B., 1013.1931, 1223.1223.A., 1223.Steel Inst., Sept. 1931; Advance copy, 1, 13; A., 1235.1235.REP. -VOL . XXTTU.

ISSN:0365-6217    

DOI:10.1039/AR9312800049

出版商:RSC    

年代:1931

数据来源: RSC

摘要:

ORGANIC CHEMISTRY.PART I.-ALIPHATIC DIVISION.01,efinic and PolyoleJinic Additions.Mono-oleJins.-The work of the past few years on the subject ofolefinic and polyolefinic addition has increasingly focused attentionon the following features of the addition process : (1) the polarisedstate of the olefin molecule, (2) the condition and manner in whichthe addendum enters reaction, (3) the point of attack in the olefinicchain (Ca, Cb, etc.), (4) the influence of substituents on the course andspeed of reaction and (5) the influence of reaction conditions (tern-perature, solvent, catalytic action, etc.). All of these enter intoconsideration in connexion with orientation problems.How profound are the effects of catalytic action on the orientationof addition products is to be gathered from the elaborate experimentsof J.P. Wibaut and his collaborators 1 on the addition of gaseoushydrogen bromide to gaseous vinyl bromide in the presence of glasswool, asbestos and of metallic bromides. I n these experiments theproportion of the isomeric dibromoethanes formed in the reactionvaried extensively with changes in the chemical composition andphysical condition of the catalyst, and quite frequently withoutassignable cause. The proportion also varied with the temperatureof interaction, but there was no interconversion of the isomeridesthemselves when heated alone, or in the presence of catalysts.Similar experiments with acetylene and hydrogen bromide indicatedthat the primary formation of vinyl bromide takes place withgreater difficulty than its subsequent conversion into dibromo-e t hanes.It has been shown by the same workers and independently byG.N. Burkhardt and W. Cocker2 that the interaction of vinylbromide with solutions of hydrogen bromide is very sensitive tochanges of temperature, concentration and solvent , and apparentlyto some extent of illumination. It is suggested by the latter authorsthat for reactions in which the molecular activations are practicallyexclusively thermal, the reactivity of vinyl bromide towards the lessconcentrated aqueous solutions of hydrogen bromide can be repre-lc-7 0sented schematically by CH,-CH-Br, in which the existence +Rec. traw. chirn., 1931, 50, 313; A., 698. Ibid., p. 837; A., 1031ORGANIC OHEMISTRY.-PART I.67of a " conjugative " effect 3 activating the @-positions for interactionwith hydrion, and a " general " effect 3 minimising the effectivenessof these polarisations, is indicated. A large fraction of the generaleffect is considered to be transmitted by paths immediately outsidethe molecule, in which circumstances it would be especially sensitiveto changes in the conditions external to the molecule such as wouldarise from changes of solvent and temperature. This effect wouldbe most important near a halogen atom. The addition in questionis a reaction which is characteristic of the ethylene bond itself; anatom or group immediately adjacent to a double bond would affectsuch a reaction by enhancing or suppressing, in some degree, one orother of the two opposite polarisations which are possible in theethylene bond.This would give a mixed product unless the polaris-ing group had a powerful effect. On the other hand, a propertywhich is not shown by the ethylene bond, e.g., addition of cyanideion to kationoid carbon, would show itself at the carbon atom moreremote from the polarising group and a single product would beexpected if the reaction proceeded a t all (compare the formation ofethylenediamine by the action of ammonia on vinyl chloride) .4Quite other considerations would enter into the discussion of orient-ation in additions promoted by light and by surface action : thechemical composition of catalytic surfaces may exert an influenceon the steric positions taken up by molecules in the adsorption layer(" directed adsorption "), but a more important influence than thisin determining the orientation of addition products is probablythe electronic distortion of the unsaturated system which takesplace in the process of adsorption.A more comprehensive hypothesis relating to the influence ofsubstituents on the orientation of olefin addition products has beenadvanced by C.K. Ingold and E. H. Ingold : 5 in this the orientationprinciples developed in connexion with aromatic substitution andtautomeric phenomena are applied with suitable modification toadditive processes. It is pointed out that when X-Y adds toR-C,=CB, the process being initiated by the orientation of( 6 +)Y to (6 -)CB (addition of Brz, HBr, etc.),6 the electron-0f hCompare J.Allan, A. E. Oxford, R. Robinson, and J. C. Smith, J.,1926, 404; A., 1926, 397; A. Lapworth and R. Robinson, Mem. Man-Chester Phil. SOC., 1927, 72, 43,ti J . , 1931, 2354; A., 1267.R. Engel, Bull. SOC. chim., 1887, [ii], 48, 96.It is admitted by the authors that addition initiated by the attack of(6 -) Hal. would also be theoretically possible, provided that the intrinsicallysmall reactivity of negative halogen could be overcome by the attachmen68 FARMER :demand made on R might have any value between a very small oneand that which corresponds to the development of a free integralcharge on C,; the actual value in a given case will depend on thatdegree of electrostriction between X and C, which is necessary todetermine the consolidation of the initial union between Y and Cg,or, in other words, on the degree to which the second stage of addition" backs up " and overlaps the first.This in turn depends, inter alia,on the degree of prior polarisation of X-Y, and the case of maximalelectron-demand will arise in the addition of previously formed ordissociated ions.The majority of those groups which activate anionotropic systemsand promote aromatic hydrogen-replacement by ordinary substitut-ing reagents will increase the additivity of an ethylene towardsreagents such as halogens, halogen halides, and nitrogen peroxide,the more active ions of which are positive, and will decrease reactivityto such addenda as hydrogen, hydrogen cyanide, nitromethane, andethyl malonate, whose more active ions are negative ; and similarlymost of those substituents which facilitate prototropy and aromatichalogen-replacement by basic reagents will deactivate the ethylenenucleus towards the former group of reagents and activate it towardsthe latter.It is recognised, however, that there are stronglyrestrictive limits to the validity of this reasoning.It should be borne in mind that when two groups are attached toan ethenoid centre, the separate groups may not compound simply.For example, if de-activation results when two substituents arepresent, it does not necessarily follow that either would act in thissense if present singly, Furthermore it is not dissymmetric sub-stitution and the consequent electrical dissymmetry of the doublelinking which constitute the primary influence of substitution ;for the electron-displacements of the addition process must besubstantially confined to the ethenoid centre and hence it is thepolarisability of the corresponding electrons, not their state ofpolarisation, which is the important factor.The classes of substituent for which distinctive effects on speedsof addition are expected to arise either when the constituent is theonly one attached to the ethylenic centre, or when if is present inconjunction with other like or unlike groups, are symbolised asfollows :of a sufficiently powerful electron-sink to the olefinic residue.It is not yetknown whether any of the available groups (GHO, GOR, 'NO,) are in factcompetent to cause this anticipated reversal of normal reactivity; the prac-tical criterion which would reveal such an occurrence would be that the rateof addition would pass through a.minimum as the efficacy of the electron-sink was progressively increasedORGANIC CHEMISTRY.-PART I. 69Class ......... (1) + I (2) - I (3) - I - T (4) - I + TClass ......... (5) + I + T (6) + I - T (7) Z t TExample ... : C + - O e :c+co,e0Example ... :C+Me :C-+NMe,@ :6%C02H :G-,BrP n 0:C---Ph u0The methyl group (Class 1) repels electrons and should thereforefacilitate the addition of a reagent such as bromine, the reactive ionof which is positive.TSI (S-1 (a+) n(&-) ........... Me+CHzzCH,. B r B rThe accumulation of methyl groups should (in the absence of groupspossessing a mechanism for electromeric change) produce, andindeed has been shown in the case of alkylethylenes to produce, aprogressive increase in the speed of addition.The carboxyl group(Class 3), the - T effect of which is weak, either alone or in thepresence of a substituent of Class 1 or 2, should invariably de-activate :this has been illustrated for acrylic and crotonic acids. Withrespect to the action of substituents of Class 4 it cannot be decideda p ~ i ~ r i whether the activating + T will fail to compensate, or willover-compensate, the de-activating - I effect; in vinyl bromideit is shown experimentally that the bromine substituent definitelyde-activates and it is to be expected that any dibromoethylene andtetrabromoethylene will exhibit strong passivity.The phenylgroup, like bromine, exhibits duplex polar action (& T) but withthe difference that both the component effects are polarisabilities :of the two electromeric effects, it is the one symbolised by + Twhich electron-demanding reaction should stimulate, wherefore thephenyl group should be an activator. The relative rates of bromineaddition to styrene and ethylene show that this is the case, and thewell-known passivity of te t rap hen ylet h ylene , and of certain otherstilbene derivatives, is probably quite wrongly attributed to de-activation by phenyl groups.The orienting influence of solvents is traced by C. K. Ingold and(Miss) E. Ramsden 7 t o that portion of the effect of a polarisinggroup which is transmitted outside the molecule itself : the latter intravelling through the medium is profoundly affected by the natureof the medium.For additions to R*CH:CH,, where R is an alkylgroup, the externally propagated orienting influence is consideredto repel electrons, anions, and the negative ends of polarised mole-cules, and to attract protons, kations, and the positive ends ofpolarised molecules. This effect must tend to orientate the adden-J., 1931, 2746; A., 139170 FARMER :dum in the sense of the expression R*CH(H)*CH,(X). Certainaspects of the problem relating to the comparison of the orientinginfluence of solvents are discussed by the same authors. I n con-nexion with the orienting influence of media, the statement that thecomposition of the product obtained by addition of hydrogenbromide to ally1 bromide in glacial acetic acid is greatly changedwhen the reaction is carried out in a magnetic field is of interest.*Information with regard to the location in the olefinic system ofthe point of initial attack does not emerge from a knowledge of thecoqstitution of the addition products.The case of the halogens is,however, amenable to practical treatment on the assumption thatthe positive end of the halogen molecule initiates reaction : thus foraddition of ICl, the location of the iodine atom in the additionproduct indicates the point of initiation of addition, and in testscarried out with propylene, styrene, and crotonic acid the resultsare found to be in accordance with the foregoing considerationsconcerning the directive influence of substituent s .gA useful review of the literature referring to the formation ofethylene chlorohydrin is contributed by E.D. GI-. Frahm.lo Thisauthor appraises the efficiency of the various practical expedientswhich have been adopted for improving the yield of chlorohydrinand depressing that of dichloride formed according to the scheme :C,H,CI, f- H,O + C1, =s H' + C1' + HOCl+ C,H,(OH)Cl.Acceleration of chlorohydrin formation and diminution of dichlorideproduction were found to result from the catalytic action of certainmetallic salts and it is suggested that chlorohydrin formation fromethylene and chlorine in aqueous media takes place by way ofethylene oxide.The degree of hydration of ethylene and propyleneproduced by heating with hydrochloric, hydrobromic, or hydriodicacid, or with aqueous solutions of various chlorides or of silvernitrate, at 100-200" does not exceed 0.6y0 even a t a pressure of800 Ib. per sq. in.; high pressures, and temperatures of 227427",are reported to favour hydration.11It is remarkable that p-chlorocrotonic acid and its sodium saltrapidly undergo catalytic reduction, although p-chlorobutyricacid does not.llU The reduction proceeds in stages-rapidly toR. H. Clarke and K. R. Gray, Trans. Roy. SOC. Canada, 1930, [iii], 24,111, 111; A., 1931, 598; see also R. H. Clarke. and E. G. Kallonquist, ibid.,p. 115; A . , 1931, 597.* C. K. Ingold and H. G. Smith, J ., 1931, 2742; A., 1391.lo Rec. trav. chim., 1931, 50, 261; A., 598.l1 R. D. Snow and D. B. Keyes, I d . Eng. Chem., 1930, 22, 1048; A , ,C. Pad, H. Schiedewitz, and K. Rauscher, Ber., 1931, 64, [B], 1521 ; A.,1562; A. V. Frost, J. Appl. Chern. Russia, 1930, 3, 1069; A., 1931, 1267.934ORGANIC CHEMISTRY.-PART I. 71crotonic acid and then more slowly to butyric acid. The differencein rate of hydrogenation between chlorocrotonic and chloroiso-crotonic acids serves to confirm the cis-tram nature of the isomerismexisting between these acids.The conclusions recently reached by A. Michael and J. Ross l2with respect to the manner in which alkylated malonic and cyano-acetic esters divide when acting as addenda in the Michael reactionare considered by N.E. Holden and A. Lapworth l3 to be erroneous.The latter authors suggest, and bring evidence in support of theview, that the apparently realisable partition of an alkylatedsodio-ester such as ethyl sodiomethylmalonate in the mannerCH,-i--CNa (C0,E t) , instead of Na-/--CMe (C0,E t)2 resultsfrom an interchange (in effect) of *CO,Et (*CN for an alkylatedcyano-ester) for the H of the CHNa group in the normal additionproduct. Thus in additions to ap-unsaturated esters of the generaltype R*CH:CH*CO,Et the normal addition product (I) may sufferextensive change to the isomeric compound (11) either intramole-cularly (e.g., via the sodio-derivative of the Dieckmann product 111)or by an intermolecular process.l4 The occurrence of such a changeunder the conditions utilised by Michael and Ross ( i e ., the employ-ment of & whole molecular proportion of sodium ethoxide for effectingcondensation) is not inconsistent with already known reactivities.R*CI-I:CH*CO,E t R*CH*CHNa*CO,E t + - 3 - 1 (1.)/ cMe(Co2Et)2CNaMe(CO,Et),R*CH*CNa( CO,Et), R*CH----- CH*CO,Et(11.1 I I >co (111.)CHMe*CO,E t CMe( C0,Et)In connexion with the characterisation of conjugated butadienesby the formation of crystalline addition products with maleicanhydride, certain olefins (e.g., styrene and indene) have beenshown to yield non-crystalline polymolecular addition products withthe same reagent; in one case (as-diphenylethylene), however, arelatively simple, although rather high-melting, crysta2Zine additionproduct has been obtained and there appears to be need for theexercise of care in applying the Diels-Alder reaction to the diagnosisof conjugated unsaturation.l6l2 J . Amer. Chern. SOC., 1930,52,4598; 1931,53,1150; A., 1931, 67; 603.13 J . , 1931, 2370; A., 1272.The transformations are represented for convenience in terms of con-l5 T. Wagner-Jauregg, Ber., 1930, 63, [B], 3213; A . , 1931, 198; Annulen,ventionally formulated sodio-derivatives.1931, 491, 172 FARMER :Polyok$ns.-A notable synthesis of an open-chain poly-ene hasbeen achieved by P. Karrer and A. Helfenstein in producing ahydrocarbon containing squalene from farnesyl bromide. l6 Theconversion is brought about in ethereal solution by the action ofpotassium or activated magnesium, and the product yields thecrystalline hexahydrochloride described by I.M. Heilbron, E. D.Kamm, and W. M. Owen.17 Squalene is therefore correctly repre-sented by the formula( CMe2:CH*CH,*CH2*CMe:CH*CH,*CH,-CMe:CH*CH2*),.Recognition that the crystalline additive compound of isoprenewith sulphur dioxide is a cyclic sulphone has been followed by theproduction of an isomeric compound by the action of ultra-violetlight on a solution of the first compound.18 The double bondappears to be retained in the original position and the possibilitythat the cause of isomerism resides in the sulphone group is rejectedon chemical grounds. The two substances yield the same dihydro-derivative and are considered to display cis- and trans- attachmentsrespectively of the *CH,*SO,*CH,* chain to the terminals of theethylenic bond, so giving planar and pleated ring configurations.An important point affecting the classification of additive reactionsin the conjugated poly-ene series turns on the mechanism of theMichael reaction.If in this reaction the addendum attacks bymeans of its anion, as in hydrogen cyanide additions,l9 then it mustbe assumed that any polarisations of the unsaturated molecule whichare capable of influencing the additive mode must exist before theanion enters the unsaturated molecule ; moreover, any plurality ofaddition products in a given instance must be explained by assumingdifferent polarisations of the butadienoid molecule, leading to theproduction of isomeric anions such as A and B, which are onlyinterconvertible via the retrograde Michael reaction (&product =Sreactants ap-product).Me*CH*gH-CH:CH*CO,Et Me*CH:CH*CH*gH*CO,Et I (*)CH(CO,Et), (4 I CH(CO,Et),(capable of prototropic change) (non-tautomeric)This is necessarily the case, since the prospect of attachment of theaddendum at the 8-carbon atom would be non-existent were it notfor the presence of a group such as carbonyl in the molecule (in otherwords, the addendum in the Michael reaction is not an additive16 Helv. Chirn.Acta, 1931, 14, 78; A., 333.17 J . , 1926, 1630; A., 1926, 816.l8 E. Eigenburger, J. pr. Chem., 1931, [ii], 129, 312; 131, 289; A., 600,la A. Lapworth, J., 1903, 83, 995; 1904, 85, 1206.1268ORGANIC CHEMISTRY.-PART I.73reagent for purely ethylenic centres) ; therefore, granting successfulattack by the anion of the reagent, it follows that the influence of theactivating group (carbonyl) is felt, and is effective in promotingreaction, at the &carbon atom-that is to say, a state of conjugationis effectively established or induced in the poly-ene chain.It has been found by E. H. Farmer and T. N. Mehta 2o that theratios in which ap- and as-ester-addition products are formed fromthe members of a series of alkyl-substituted butadiene-a-carboxylicesters are not those to be expected on the basis of an anionotropicallycontrolled incidence of addition products. Taking sorbic ester asthe standard, it is seen from the figures quoted that (a) deprivationCH,-CH:CH*CH:CHX 7-10 CH,*CH:CH*CH:CX, no additionCH,:CH*CH:CHX (2” CH,CH:CMe*CH:CHX 70-74.5CH,CH:CH*CMe:CHX (7 CH,*CH:CH*CH:CHAc 27-29CH,*CMe:CH*CMe:CHX no addition* Not exactly determined.of the S-methyl group, or introduction of a p-methyl group, repressesap-addition, (b) introduction of p- and S-methyl groups, or intro-duction of an a-carbonyl group, represses both ap- and as-addition,and ( c ) introduction of a y-methyl group, or replacement of thecarboxylic activating group by acetyl, strongly augments orp-addition.Modification of the ester addendum appears, as might be expected,only to affect the ease of addition.J.Bloom and C. K. Ingold 21 regard Farmer and Mehta’s resultsand certain supplementary results which they furnish relating toa-methylsorbic ester (not more than 2% ap-addition), cinnamylidene-acetic ester (entirely or almost entirely ap-addition), and styryl-cinnamic ester (little or no addition) as defkitely supporting the viewthat the reagent attacks in the form of its anion.They assumethat the conductivity of unsaturated ions, including dipolar ions,guarantees the distribution between CS and Cp of the positivecharge produced by the primary polarisation, whilst the greaterlability of double-bond electrons than of single-bond electronsdetermines the dominant reactivity of CS :aP (%I* aP (%I*(sorbic ester)[X = CO,R]This holds provided the conditions of substitution in the CS : C,,- andCp : C,-units, which determine the respective degrees of reversibility2o J., 1930, 1610; 1931, 1904, 2661; A., 1930, 1163; 1931, 1397.21 Ibid., 1931, 2765; A., 1391.c 74 FARMER :of the corresponding addition reactions, are comparable.The effectof modifying the existing state of substitution in the sorbic estersystem should then be of the kind observed, the phenyl groupexerting the orienting influence by virtue of its electron-releasingproperties.The formation, under suitable conditions of reaction, of ana@ -es ter - addition product of ethyl muconate, almost entirely freefrom isomerides, has confirmed the view that the extensive pro-duction of my-products formerly noted is to be attributed to @,Py-equilibration in the presence of sodium ethoxide.22I n hydrogen halide addition to conjugated compounds it might beanticipated that the hydrogen atom of the hydrogen halide molecule,probably as the ion, would initiate attack, and experiments intendedto test this point have been carried out.Here, however, thepossibility of attack a t the p- (or @'-)carbon atom of the butadienechain enters. Experiment shows that the mode of addition ofhydrogen bromide to @y and a8-dimethylbutadiene is compatiblewith reaction initiated at the terminal carbon atom, and completedin accordance with anionotropic principle^.,^The same questions as to which ion or pole of the addendummolecule initiates reaction, and which atom of the conjugatedmolecules furnishes a seat of attack, enter into the consideration ofadditions by other unsymmetrical reagents such as iodine chloride.C.K. Ingold and H. G. Smith 24 find that this reagent, when addedto butadiene, behaves in a way which might be anticipated on thebasis of the mechanism imputed to bromine addition : 25 a mixtureof CH,I*CH:CH*CH,Cl and CH,I*CHCl*CH:CH, is formed, con-formably with the initial entrance of iodine at the a-carbon atom.The results of I. E. Muskat and H. E. Northrup for the additionof chlorine to butadiene 26 confirm expectations based on knownresults for bromine addition,,' as to the simultaneous formation of@- and a6-dichlorides. Other statements of Muskat and hiscollaborators 2* relating to the 78-hydrogenation of p-vinylacrylicCompareE. H. Farmer, ;bid., 1923, 123, 3324.Furtherhydrobromination results (unpublished) obtained at the same time by theseauthors, which refer to piperylene and aa-dimethylbutadiene, can be bestexplained on the basis of hydrion attack initiated at the a- (or a'-) carbon atom.22 E.H. Farmer and T. N. Mehta, J . , 1931, 1762; A., 1037.23 E. H. Farmer and F. C. B. Marshall, ibid., 1931, 129; A., 460.24 Ibid., p. 2752; A., 1391.25 Ann. Reports, 1 9 2 8 , s . 131.26 J . Amer. Chem. SOC., 1930, 52, 4043; A., 1930, 1553.27 E. H. Farmer, C. D. Lawrence, and J. F. Thorpe, J . , 1928, 729; A . ,1928, 604.28 I. E. Muskat and B. Knapp, Ber., 1931, 64, [B], 779; A., 719; I. E.Muskat and L. Hudson, J . Amer. Chem. SOC., 1931, 63, 3178; A., 1148ORGANIC CHEMISTRY.-PART I. 75acid under catalytic conditions and the (apparently complete)formation of a @-addition product of the same acid with hypo-chlorous acid are inadequately established by the published experi-mental evidence : moreover, unpublished observations by the writerand his collaborators show that the statements only partiallyrepresent the facts.Isomeric forms (two) of apy8-tetrachlorobutadiene are obtainedas a by-product in the preparation of trichloroethylene from tetra-chloroethane by elimination of hydrogen chloride.29 The formationof both saturated and unsaturated four-carbon molecules fromhexachloroethane takes place apparently with moderate facility,but reversion to a two-carbon molecule (hexachloroethane) has onlybeen accomplished by exhaustive chlorination of the halogenateddiene .Acids.New instances of polporphism amongst carboxylic acids andesters have been recognised. Malonic, succinic, and glutaric acidsare dimorphous, the curve of transition points following a similarcourse to that of the melting p0ints.~0 Ethyl palmitate, ethylstearate, cetyl acetate, octadecyl acetate, ethyl cetylmalonate (aswell as cetyl chloride) have also been found to be dim0rphous.3~It isfound that sodium antimonyl tartrate (tartar emetic itself is tooinsoluble for freezing-point determinations to be made) is presentin the unimolecular condition in dilute aqueous solution, and itappears by analogy with a-phenylethylammonium and p-nitro-a-phenylethylammonium antimonyl tartrate, which contain nowater of crystallisation, that the water of tartar emetic is not con-stitutive.Tartar emetic is only weakly acidic, but is easily esterified :A new formula has been proposed for tartar emetic.32consequently only one carboxyl groupcan be bound to antimony.TheOH2 formula (I) is advanced which differsfrom Schiff’s formula in the addition0:y.oHy.o>Sb. . . . .(1.1 CO,K*HC*Oof a water molecule attached t o antimony by a residual valency.It represents an unstrained condition as shown by models andis supported by the fact that the water molecule in bariumantimonyl tartrate, although not in tartar emetic itself, is re-placeable by pyridine, the product probably existing as the acid29 E. Miiller and F. Huther, Ber., 1931, 64, [ B ] , 589; A . , 597.so F. D. laTour, Compt. red., 1930,191, 1348; 1931,193, 180; A., 1931,91 J.W. C. Phillips and S. A. Mumford, J., 1931, 1732; A., 1003; J. C.82 H. Reihlen and E. Hezel, Annalen, 1931, 487, 213; A., 936.198, 1036.Smith, ibid., p. 802; A., 68476 FARMER :[C,H,N . * * . SbC,H,O,]H in the solid state, and as the salt[H20 * * . - SbC,H206]H,C5H5N in solution. The existence ofthe auxiliary valency in (I) is supported by the loss of wat,er fromthe sodium salt in an evacuated vessel at room temperature (but fr0.mthe potassium salt, only a t 120") and by the existence of the freeacid only in the anhydrous form. Unlike the corresponding boronand arsenic compounds, tartar emetic is only slightly hydrolysed toHK(C,O,H,) and Sb(OH),, but its acid reaction is due to "intra-molecular hydrolysis. "Measurements of the specific conductivity of the complexesformed by tartaric and boric acids in solution have led M.Amadori 33(I) Dextro. (11) LZVO. (111) Meso.to the conclusion that the spatial disposition of the groups in thethree tartaric acids is to be represented by the models (I, 11, and 111),rather than by the well-known Fischer models in which the carboxylgroups are on the same side of the molecule. It is considered thatboric acid complexes are formed to about equal extents by the activeand inactive acids and that they contain two (*O*CH*CO,)BOHgroups which are disposed on opposite sides of the molecule; thesegroups if projected on to a plane normal to the axis of the centralcarbon atoms would have the relative dispositions indicated infigures IV and V.83 Bazzetta, 1931, 61, 216; A., 822ORGANIC CHEMISTRY .-PART I.77Various views have been put forward with regard to thespontaneous decomposition of dihydroxymaleic acid in aqueoussolution according to the equationHO,C*C( OH):C( OH)*CO,H -+ OH*CH,*CHO + 2C0,The suggestions have in turn been made that the decompositiondepends on hydration of the acid to trihydroxysuccinic acid, or theproduction of the bivalent negative ion ( C4H206)", and consequentlyon the ionising power of the medium, on the production of theunivalent negative ion (C,H,O,)', and finally on the concentrationof the undissociated acid solvated on the carboxyl group. It is nowshown from the relation existing between the velocity coefficient ofdecarboxylation and the degree of dissociation of the free acid, itslithium hydrogen salt, and lithium salt solutions of varying pH, thatthe univalent ion (C4H306)' is the actively decomposing consti-tuent.,5 The decomposition of the free acid appears to occur atthe velocity for the ion and the ratio of the ionisation coefficientsof the acid is that of a tram-acid of this series.Boric acid exerts astabilising action proportional to its own concentration and that ofthe dihydroxy-acid, and st kinetic investigation points to theformation of an equimolecular complex. Organic solvents depressthe formation of the active ion and forthe solvents water, acetonitrile, methylinverse proportionality of - log k (fordecarboxylation) is established. The catalytic influence on thedecomposition of the salts of heavy metals and of weak bases hasalso been studied.Conditions for the catalytic hydrogenation of carboxylic acids andesters to the corresponding alcohols have been investigated by anumber of workers.36 Various catalysts (copper chromite, nickel,cobalt, copper, etc.) are used in conjunction with high pressures, andtemperatures ranging from 250" to above 300"; at temperaturesabove 350" reduction can be carried to the hydrocarbon stage. It isnot essential, however, for the smooth reduction of the carboxylgroup to use high pressures, and provided a sufficiently activecatalyst is employed3' there is no hindrance to bringing about34 H.J. H. Fenton, J., 1895, 67, 774; 1905, 87, 804; S. Skinner, ibid.,1898, 73, 483; A.Locke, J. Amer. Chem. SOC., 1924, 46, 1246; A., 1924, i,708.(p2H R'o>B<oH OH+ alcohol, ethyl alcohol, and acetone theH02(JY-C*035 W. Franke and G. Brathuhn, Annalen, 1931, 487, 1; A., 936.86 W. Normann, 2. angew. Chern., 1931, 44, 714; A., 1269; H. Adkinsand K. Folkers, J . Amer. Chern. SOC., 1931,53, 1095; A., 698; W. Sohrauth,0. Schenck, and K. Stiokdorn, Ber., 1931, 64, [B], 1314; A., 932.87 0. Schmidt, Ber., 1931, 64, [B], 2061; A., 126878 FARMER :reduction a t atmospheric pressure ; thus, ethyl oleate in the presenceof copper chromate a t 270-280" yields octadecyl alcohol.Oleic acid is convertible to the extent of 50% into elaidic acid byheating with sulphur ; 38 erucic acid is likewise stated to be smoothlyconverted into brassidic acid when heated with 30% nitric acid andsome sodium nitrite.39 Oleic acid suffers oxidation by dilutepermanganate solution into the corresponding elaido- and oleo-dihydroxystearic acids; both of these substances, as well as thecorresponding dibromostearic acids, are resolvable through thestrychnine salts ; oleo-dichlorostearic acid is reported to yield withalcoholic potash stearolic acid and Aqt-octadecadienoic acid, thelatter of which is in turn convertible into stearolic acid by heatingwith the same reagent at a higher temperature.m From the parachorvalues obtained for oleic, elaidic, AB-oleic, erucic and brassidic acidsit is concluded that oleic and erucic acids have a &-configurationwhereas elaidic, M-oleic, and brassidic acids have a trans-con-f i g ~ r a t i o n .~ ~ The hydroxyoleic acid from ergot oil has beeninvestigated and found to be exactly similar in its physical con-stants and behaviour on oxidation to ricinoleic acid : the twosubstances are concluded to be identical.42 cis- and trans-Forms oferucylacetic (AE-tetracosenoic) acid have been synthesised, and theformer found to be identical with nervonic a ~ i d . 4 ~An observation which has an important bearing on currentattempts to determine the constitution of the higher unsaturatedfatty acids concerns the isomerisation of mono-olefinic esters duringcatalytic reduction. Methyl oleate, palmitoleate and erucate, whentreated a t 114-220" with insufficient hydrogen to produce completesaturation (nickel-kieselguhr catalyst), yield mixtures of esters inwhich unsaturated isomerides of the original esters occur ; thedouble bond in these isomerides occupies a position adjacent to thatit occupied in the original compounds, and both the original com-pounds and their isomerides appear to be present in cis- and trans-forms.44 Possibly the isomerisation is to be attributed to the com-38 G.Rankov, Ber., 1931, 64, [B], 619; A., 601.39 Idem, J . pr. Chem., 1931, [ii], 131, 293; A., 1272.40 Y. Inoue and B. Suzuki, Proc. Imp. Acad. Tokyo, 1931, '7, 261, 265;A., 1271.41 G. B. Semeria and G. Ribotti-Lissone, Guzzettu, 1930, 60, 862; A . , 1931,149.42 H. Matthes and 0. H. Kurschner, Arch. Phurm., 1931, 269, 88, 101;A., 602.43 J. B. Hale, W.H. Lycan, and R. Adams, J. Arner. Chem. SOC., 1930,52, 4536; A., 1931, 65.44 T. P. Hilditch and N. L. Vidyarthi, Proc. Roy. SOC., 1929, [ A ] , 122, 562;A . , 1929, 423; A. Steger and H. W. Scheffers, Chem. Umschuu, 1931, 38, 45,61; A., 711ORGANIC CHEMISTRY.-PART I. 79paratively high temperatures employed, since oleic acid is found tosuffer isomerisation to the A1-acid when heated at 250" in contactwith alumina ; at any rate the occurrence of isomerism presentsa complicating factor in the determination by reductive proceduresof the number and constitution of the polyolefinic acids which occurin natural products.T. P. Hilditch and N. L. Vidyarthi have deduced from the natureof the oxidation products of partially hydrogenated methyl linoleatefrom soya bean and cotton seed oil that the unsaturation is ofAoA-ty~e.~~ Y.Inoue and B. Suzuki have found by a similar methodthat a methyl isolinoleate derived from the oil of silkworm pupae isalso a A%ompound but differs from linoleic ester in having a&-configuration about the &-double bond.47CH,*[CH2I4*CH:CH*CH,*GH CH,-[CH,],*CH:CH*CH,$HCH*[CH,],*CO,H H0,C*[CH2]7*CHBy debrominating a solid tetrabromostearic acid prepared frompoppy and soya bean oils, W. C. Smit 48 has obtained an oily linoleicacid (m. p. - 12" to - 11") to which the A%onstitution is assigned ;by thermal dehydration of ricinelaidic acid, however, he obtained aproduct consisting of a solid AeK-compound (m. p. 54") admixed withliquid (probably stereoisomeric) isomerides ; likewise by the distill-ation of ricinoleic acid he obtained an oily mixture which appearedto contain both AeA- and AeK-linoleic acids, including a second form(m.p. 56") of the AeK-acid. The constitutions of the unsaturatedacids were determined by ozonisation.The conjugated AeK-linoleic acid and its ethyl ester combinenormally with maleic anhydride and by means of this reaction it hasbeen verified that the dehydration product of ricinoleic acid containsboth AOA- and AeK-holeic acids (about 15% and 75% respe~tively).~~Ethyl AeK-linoleate when partially hydrogenated is stated to yieldethyl Ah-elaidate, probably of the elaidic acid configuration. 5oEarlier work on the partial hydrogenation of ethyl linolenateindicated that, although some isomerisation occurs in the process,the unsaturated centres are probably to be assigned to 01- andAppositions and also to a point beyond the fourteenth carbon atomof the chain.46951 Later results obtained by partial hydrogenation4 5 K.H. Bauer and M. Krallis, Chem. Umschau, 1931, 38, 201; A . , 1034.4 6 Proc. Roy. Soc., 1929, [ A ] , 122, 563; A., 1929, 423.47 Proc. Imp. Acad. Tokyo, 1931, 7 , 15; A., 601.48 Rec. trav. chim., 1930, 49, 539; A., 1930, 891.49 J. Boeseken and R. Hoevers, ibid., p. 1166; A., 1931, 198.50 Idem, ibicl., p. 1161; A., 1931, 196.6 1 T. P. Hilditch, Chem. Umchau, 1930,37, 354; A., 1931, 335.Linoleic mid iSoLinoleic aci80 FARMER :methods indicated that the linolenic acid prepared from the solidhexabromide was a Aenbornpound and suffered hydrogenation instages, the OL- and go-linkings being reduced more readily than thehp-linking ; furthermore no migration of double linkings duringhydrogenation was noticed.52 It has since been concluded 53 thatthe AA-linking is first saturated, yielding AeE-octadecadienoic acid,from which the A”-isomeride is formed by shifting of the unsaturatedlinkings. On treatment with 2 mols.of hydrogen the remote doublelinkings of these two diolefinic acids are saturated, forming At- andAe-oleic acids, the latter of which yields the AT- (and probably At-)acid by isomerisation.Couepic acid, a new isomeride of elzostearic acid, which occursin the oil from Couepia grandijlora, gives oxidation products whichindicate that the acid is a geometrical isomeride of the knowna- and @-forms of elzeostearic acid,CH3*[CH,]3*[CH:CH]3*[CH2],*C02H.54Behenolic acid has been synthesised from the undecenoic acidobtainable from castorKetones.W.Bradley and R. Robinson 56 found that dibenzoylmethanes,R*CO*CH,*CO*R,, suffered fission by aqueous caustic soda in such away that the stronger of the two acids R*CO,H and R,*CO,H wasin nearly all cases produced in the greater relative amount. Thefission was considered to be a characteristic of the diketonic phasesof the tautomeric system present and the hydrolysis was thoughtprobably to result from the formation and decomposition of acomplex anion as in the scheme :R*CO*CH,*CO*R, + 8H + R*C(OH)(8)*CH2*CO*R1 -+RC8, + H*CH,*CO*R,Hence the chief factors controlling the change were taken to be( a ) the rates of formation of the two possible complex ions and ( b )the extent to which each of these breaks down with the formationof carboxylate ions.Experi-ments on the alkaline hydrolysis (0.1N-sodium hydroxide) and the1271.Several recent researches bear directly on this question.61 K.H. Bauer and E. Ermann, Chem. Umschau, 1930, 37, 241 ; A., 1930,b3 H. van der Veen, ibid., 1931, 38, 89; A., 712.54 J. van Loon and A. Steger, Rec. trav. chim., 1931, 50, 936; A., 1034;compare J. van Loon, ibid., p. 638; A., 822.55 R. Bhattacharya and J. L. Simonaen, Proc. X‘v. Indian S C ~ . Cong., 1928,153; A., 1931, 1271.6 6 J . , 1926, 2366; A., 1926, 1145ORGANIC CHEMISTRY.-PART I.81acid alcoholysis (alcoholic hydrogen chloride) of nine unsymmetricalP-diketones of the general formula CH,*CO*CHR*CO*R’ show thatthere is no relationship between the amounts of acid produced byfission and their strengths.57 The hydrolysis and the alcoholysisfigures differ considerably and it is suggested that the ratio of theamounts of CH,*CO,Et and R*CO,Et produced by alcoholysis is ameasure of the extent of enolisation of the respective carbonylgroups. Further experiments on the rate of alkaline alcoholysis(alcoholic sodium ethoxide) of six p-diketones and five p-ketonicesters 58 show that, although the ketonic esters are the more stable,the rate of alcoholysis of both diketones and ketonic esters increasesvery greatly with substitution on the carbon atom between thecarbonyl groups.The rate of alcoholysis of the diketones has beenmeasured in the presence both of hydrogen chloride and of sodiumethoxide and it is found that arrangement of the diketones in theorder of decreasing reactivity with respect to acid alcoholysispresents them (with one exception) in the order of increasing react-ivity towards alkaline alcoholysis. Diethyldibenzoylmethane, whichcannot enolise, readily suffers alcoholysis and hydrolysis.A. Michael and J. Ross 59 have formed the opinion that carbonylderivatives which do not form enolates with alkali react primarilyby addition of the alkali to the carbonyl group to form the group>C(OM)(OH). The slightly neutralised energy of the alkali in thiscomplex loosens the affinity of the C-atom for the directly attachedC-atoms so that cleavage can occur by hydrolysis.The ruptureshould take place at the carbon linking which is most weakened bythe positive influence of the alkali atom. Fission, however, is notdenied to enolic centres, and the fission of a sodium enolate byaqueous alkali is represented thus :R*CO*CH:C( ONa)R, + H,O + R-CO*CH,-C( ONa) (OH)*R, +R*CO*CH, + R,*CO$aAs regards the point of hydrolytic fission in the @-diketone molecule,it is considered that if the energy of the metal, in the alternativelyformed enolates ROC( ONa):CH*CO*R, and R*CO*CH:C( 0Na)-R,, ismore effectively neutralised in the first than in the second, fissionwill occur preferentially at the enolic centre of the second ; the pointa t which p-diketones are attacked by ordinary carbonyl reagentsdepends on whether the latter add more facilely to the carbonyl than5 7 W.M. Kutz and H. A h , J . Amer. Chem. SOC., 1930, 52, 4036; A.,s8 Idern, ibid., p. 4391; A., 1931, 69. Compare N. L. Drake and R. W.69 Ibid., 1931, 53, 2394; A,, 1035.1930, 1559.Riemenschneider, ibid., p. 5005; A., 1931, 19782 FARMER :to the *C(OH):C* group. Michael and Ross have also sought to showthat “ the principle of maximum neutralisation ” satisfactorilyexplains the course of reaction in the alkylation of mixtures of enolicesters or of a substance such as or-acetyl-or’-carbethoxylsuccinicester,60 when the enolic centres in each instance are made to competefor sodium.The experimental results are striking and are held toshow that the velocity relations applying to the action of alkylhalide upon the sodio-derivatives which are present, depend upon thefree positive energy of the sodium : thus, the proportions of thesodium enolates present a t the beginning of reaction become ofimportance only when the respective velocities of reaction are nearlyequal.All ketones which are structurally capable of enolisation, althoughnot necessarily appreciably enolised under ordinary conditions,appear to suffer displacement of the keto-enol equilibrium in favourof the enolic forms in the presence of excess of Grignard reagents :the enolic forms are thereby fixed as magnesium organo-enolates anda volatile hydrocarbon is liberated.61 Now when Grignard reagentsinteract with @-diketones, relatively normal products are obtainedonly from those compounds which are largely or entirely enolic.62Then two molecules of the reagent enter into reaction, liberating onemolecule of hydrocarbon, thus :PhMgX PhMgX Ph*CO*CH,*COPh --, Ph*H+Ph*C(OMgX):CH*COPh ~ 3Ph*C( OMgX):CH*CPh,*OMgX 4 Ph*CO*CH,*CPh,*OH.If the diketones are added to only one equivalent of the reagent,half of the material is recovered unchanged.The little-enolisedmono- and the di-substitution products of these simple diketonesalso react with two equivalents of the reagent. Addition takesplace to one of the carbonyl groups and the resulting magnesiumcompound suffers fission :PhMgX PhCO*CHPh*COPh -+ Ph*CO*CHPh*CPh,( OMgX) +PhMgX Ph*C( 0MgX):CHPh + Ph,CO --f Ph,C( OMgX).A similar kind of cleavage takes place when oxido-ketones aretreated with Grignard reagents.636o The assumption that the position which the alkyl group ultimatelyoccupies in this compound is necessarily that at which it enters duringalkylation appears to be no more justified than the similar assumption withrespect to the position taken up by the alkyl group of an alkylated addendumin the Michael reaction (compare p.71).61 Ann. Reports, 1930, 27, 100; V. Grignard and H. Blanchon, Bull. SOC.chim., 1931, [iv], 49, 23; A., 465.E. P. Kohler and J. L. E. Erickson, J . Amer. Chem. Soc., 1931,53, 2301 ;A., 1060.63 E. P. Kohler, N. K. Richtmyer, and W. F. Hester, ibid., p. 205; A., 354ORGANIC CHEMISTRY.-PART I.83The r61e of sodium in the acetoacetic ester condensationwhetheras true condensing agent or as a mere generator of sodium ethoxide-has been the subject of renewed discussion. The fact is stressed thatsodium produces two distinct types of reaction with aliphatic esters,wix., the acetoacetic ester and the acyloin types of condensation.64The metal itself is considered to be the direct cause of the acyloincondensation and to produce a t the same time sodium ethoxide :2R*CO,Et 5 ONa*CR(OEt)*CR(OEt)*ONa 2ONa*CR:CR*ONa + 2NaOEt.There are no data available to show whether the primary additionproduct reacts directly with more sodium or first loses sodiumethoxide to yield the free diketone; there is no need, however, toassume that reaction proceeds, when possible, through the enolform, or to postulate special mechanisms to account for the slownessof reaction of an ester which cannot enolise.With regard to theacetoacetic ester condensation it is deduced, from the proportions ofacetoacetic ester, alcohol and hydrogen which are actually producedby the action of sodium on ethyl acetate, that the r6le of the metal isimprobably other than that of a generator of sodium ethoxide, thelatter being the real condensing agent.It has been shown that the catalytic reduction of ethyl aceto-acetate in the liquid phase in presence of a nickel catalyst yieldsmixtures of ethyl p-hydroxybutyrate and the condensation productCHMe(OH)*CH2*C02*CHMe*CH2*C02Et. 65 The latter is the reduc-tion product of the compound which is usually supposed to be anintermediate in the formation of dehydracetic acid and would point tothe possibility that the formation of bimolecular reduction productsof the kind in question is related to the enolising capacity of theparticular acetoacetic ester employed, under the actual conditionsof its reduction.This view is supported by the results of experi-ments in which no solvent, and solvents of different ionising powerare employed, and by use of acetoacetic esters incapable of ionisation.The function of the base employed as condensing agent in theKnoevenagel and allied reactions remains obscure in spite of severalnew investigations. The first stage of the union, without condensingagent, of formaldehyde with malonic ester (to yield hydroxymethyl-malonic ester) 66 constitutes a bimolecular reaction, the velocity of64 J.M. Snell and S. M. McElvain, J . Amer. Chem. Soc., 1931,53,750,2310;A., 464, 1035. Compare B. B. Corson, W. L. Benson, and T. T. Goodwin,ibid., 1930, 52, 3988; A., 1930, 1559.66 H. Adkins, R. Connor, and H. Crarner, ibid., 1930, 52, 5192; A., 1931,197.66 K. N. Welch, J., 1931, 653; A., 603; compare A. C. 0. Hann and A.Lapworth, ibid., 1904,85,46; E. Hope and R. Robinson, ibid., 1911;99, 211784 FARMER :which varies inversely as the hydrogen-ion concentration ; ifammonia or trimethylamine is added as catalyst, the pH value of themixture not being allowed to change, little acceleration of thereaction ensues, but if piperidine is added rapid acceleration setsin.I n the reaction between cinnamaldehyde and malonic acid(in aqueous alcohol), however, the velocity of reaction increases withincrease in the hydrogen-ion concentration if the catalyst be one ofvarious amino-acids ; 67 moreover, urea and similar weak bases whendissolved in acetic acid are found to form very efficacious catalystsfor the Knoevenagel reaction. The catalytic influence in the lattercases is imputed to the kation of the amino-acid or the kation of thehighly-dissociated salt formed from the weak base and acetic acid.I n the Doebner reaction (more properly designated, it appears,the Verley reaction) the nature of the condensation product cannotbe correlated with the order of the base employed.68 Further, it isclear that the action of pyridine in yielding @-unsaturated acids isquite abnormal with respect to the general action of bases (even ofother tertiary bases, or bases of similar strength) although, remark-ably enough, the use of traces of pyridine leads to the production ofnormal py-unsaturated products.The catalytic activity of the basemight presumably here also be imputed to the kation of a salt formedwith malonic acid but could not generally be attributed to thelowering brought about by the base in the acidity of the medium.W. Cocker, A. Lapworth, and A. T. Peters 69 show that thePinner-Kotz theory with respect to the action of potassium cyanideand chloral in forming potassium dichloroacetate is capable ofextension to cover a group of reactions including the conversion ofcyanohydrins into amino-nitriles (a reaction proceeding by way ofthe free aldehyde or ketone), and the reversible formation of acetals.Some details with regard to the reactivity of ketones in acetalformation are recorded by G.F. Pfeiffer and H. Adkins.'OOxidation Processes and Peroxides.Several noteworthy attempts have been made to throw light onoxidation processes which employ or involve the formation ofperoxide compounds : these comprise oxidations by ozone, byhydrogen peroxide, and auto-oxidation processes.Ozonisation of an undiluted aldehyde gives rise to a mixture of thecorresponding acid and peracid, containing the former in excess :C7 K. C. Blanchard, D. L. Klein, and J.MacDonald, J . Amer. Chern. SOC.,1931, 53, 2809; A., 1017.6 8 S. E. Boxer and R. P. Linstead, J., 1931, 740; A., 935.69 Ibid., p. 1382; A., 1037.70 J . Amer. Chem. Soc., 1931, 53, 1043; A., 606ORGAXIC CHEMISTRY.-PART I. 85in this way the whole of the ozone is used up (2R-CHO + 0, --+R*CO,H $- R*CO,H). On the other hand, ozonisation of thealdehyde in solution causes more extensive oxidation than isaccounted for by the amount of ozone used; it is suggested in thiscase that ozone itself catalytically promotes interaction between theozonide first formed and oxygen (R*CHO,O, + 0,+ R*CO,H + 0,),and this behaviour probably also characterises the ozonisation ofolefins in solution. 7 1From the form of ozone-absorption curves relating to unsaturatedhydrocarbons treated with ozonised oxygen, G.Brus and G. Peyres-blanques 72 have concluded that the primary products of reactionare normal ozonides and that the number of double linkings can bededuced from the data. Perozonide formation appears to occursubsequently, probably by addition of an atom of oxygen at theketo-group. A recent re-examination of the well-known “ lsvulicaldehyde diperoxide ” of Harries 73 has shown that this substance isa decomposition product of caoutchouc ozonide, which is progressivelyformed when solutions of’ the latter are allowed to stand for a longtime. It can be obtained in yields representing 15-20% of thecarbon skeleton in the caoutchouc employed. In character it isacidic, peroxidic, but non-aldehydic : it does not behave as a peracidbut yields lzevulic acid (over 90% yield) on reduction with aluminiumamalgam.The formula (A) of Harries is replaced by the bimolecularformula (B).CH,*C*CH,*CH,*CH*O CH,*C*CH,*CH,*CO,H0\4 0 AA. Rieche and his collaborators have shown that aldehydes readilyunite with alkyl hydrogen peroxides to give monohydroxydialkylperoxides, R*CH( OH)*O*OR, and with hydrogen peroxide itself togive hydroxyalkyl hydrogen peroxides, RCH( OH)*O*OH, and thecorresponding di- a-hydroxyalkyl peroxides. Ethylidene peroxide,it is interesting to note, could be obtained not only by dehydrationof hydroxyethyl derivatives (mono- or di-), but also by warmingbutylene ozonide or by the auto-oxidation of ethyl ether. The modeof decomposition of these substances is de~cribed.7~71 F. G.Fischer, H. Dull, and J. L. Volz, AnmaZen, 1931,486, 80; A., 604.73 R. Pummerer, G. Ebermayer, and K. Gerlach, Ber., 1931, 64, [B], 804;A., 733.I4 A. Rieche and F. Hitz, ibid., 1930, 63, [B], 2642; A., 1930, 1554; A.Rieche and R. Meister, ibid., 1931, 64, [B], 2328, 2335; A., 1267, 1268.Compt. rend., 1930,190, 601; A., 1930, 44986 FAl3MER :The oxidation of malonic, tartaric, maleic and similar dibasic acidsby means of hydrogen peroxide at 100" proceeds through an acid-hydrogen peroxide complex but does not involve the formation of aperacid; 75 the oxidation of formaldehyde by acidified hydrogenperoxide is stated to yield either formic acid and hydrogen(2CH,O + H202 I_, BH*CO,H + H,) or formic acid and water.76Considerable interest attaches to the suggestion that the auto-oxidation of ethers proceeds by addition of molecular oxygen to theethereal oxygen atom.77 The immediate product is represented tobe of oxonium type and suffers decomposition in two different ways :(R-CH2),0 -+ (R*CH,)28*O*8 _I, R-EH, + R*CH,*O*O*8R*CH,*O*O*O*CH,R + R*CHO + H,O --F --+ R*CH,*OH+R-CH,*O*O*OH + R*CH,*OH+R-CHO+H,ODifferences which have been observed in the behaviour of peraceticand perbenzoic acid towards unsaturated substances are now foundto be only of secondary character : both reagents form primarilycyclic oxides, but fission of the oxide ring may occur subsequentlyunder the conditions of reaction.78 Solutions of peracetic acid havebeen applied to the determination of the degree of unsaturation inoils and fats 79 and i t is claimed the method gives in the cases examinedresults which are in agreement with the Wijs iodine values and aremore concordant than those obtained by the perbenzoic acid methodof Nametkin and Abakumovski. Apparently, however, oxidationat the ethylenic linking does not inevitably occur with peracids,80since styryl methyl ketone is reported to yield p-phenylvinyl acetatewith perbenzoic acid (CHPhXHAc + CHPh:CH*OAc).Oxidationof the acetylenic linking takes place less readily than is the case withthe ethylenic linking and follows, when it occurs, a more complicatedcourse of reaction.slPolymerisation.For many years opinion has been divided between the " cyclo-butane " formula of Kramer and Spilker for dicyclopentadiene, andthe cyclohexene formula of Wieland.The isolation of cydopentane-7 5 W. H. Hatcher and W. H. Mueller, Canadian J . Res., 1930, 3, 291; A.,1930, 1558.76 H. S. Fry and J. H. Payne, J. Amer. Chem. SOC., 1931, 53, 1973; A.,819.7 7 N. A. Milas, ibid., p. 221; A., 334..J. Boeseken and G. C. C. C. Schneider, J . pr. Chem., 1931, [ii], 131, 285;A., 1150.?* W. C . Smit, Rec. trav. chim., 1930, 49, 691; A., 1930, 1020.J. Boeseken and A. Kremer, ibid., 1931, 50, 827; A., 1050.81 J. Boeseken and G. Slooff, ibid., 1930, 49, 95; A., 1930, 322ORGANIC CHEMISTRY .-PART1 : 3-dicarboxylic acid from amongst the oxidation products of thedihydrogenated dimeride shows that Wieland's formula is correct(KGamer and Spilker)(Wieland)Thus dimerisation of a simple cyclic butadiene is now definitelyknown to follow the course which is characteristic of the open-chainbutadienes.S2 Further polymerisation, leading to the formation oftri-, etc., cyclopentadienes, probably occurs at the reactive ethylenelinking in ring (2).The dimeride of isoprene, obtained together with dipentene andcaoutchouc by heating the hydrocarbon alone or with aceticis a 1 : 3-menthadiene; formerly this com-pound was regarded by Harries as a CHMe A/ \ dimethyloctatriene.Similarly the dimer- Erne ide obtained by heating apyS-tetramethyl-\ / butadiene with concentrated formic acidYHMev CHMe is the met hylpropenylhexamet hylcyclo-Degradation of the triisobutylene pre-pared by the action of sulphuric acid on tert.-butyl alcoholindicates that the polymeride is produced in conformity withthe additive mechanism indicated in the scheme :CMe,:CH, CMe2*CH, CMe,:CH, CMe,*CH,(14 hexene (I). 84+ = I Y I - + CMe,: C [ HI CMe , CMe,:C* CMe , CMe,:CH[H] CMe,:CHTwo additional isomerides of the final product appear, however, tobe formed, and these could arise if double-bond movement occurreda t the dimeride, and at both dimeride and trimeride stages of thepolymerisation, respectively.85If polymerisation of this type be considered to apply to butadienoid ,hydrocarbons, it is obvious that by taking into account both aP- andas-types of addition, long polymeric chains could be formulated inwhich the same isopentene unit occurs indefinitely but the end groups82 K.Alder, G. Stein, and H. Finzenhagen, Annalen, 1931, 485, 223; A.,473.** T. Wagner-Jauregg, ibid., 1931, 488, 176; A., 1031.81 P. van Romburgh and G. van Romburgh, Proc. K . Akad. Wetensch.a5 R. J. RlcCubbin, J . Amer. Chem. SOC., 1931, 53, 356; A., 333.Amsterdam, 1931, 34, 224; A., 81988 FARMER :change according to the additive scheme adopted. Thus, if for theunsymmetrical compound, isoprene, it be assumed that the adden-dum molecule may (in effect) divide in the mannerH-CH:CH*CMe:CH, or H-CH:CMe*CH:CH,and add at the aP- or as-positions of the conjugated monomeride,dimeride, etc., hydrocarbon, then six formulations become possiblein which the unit (CH,*CH:CMe*CH,) = U recurs but the end groupschange ; in this way the polymerides (A), (B), (C), etc., are formed : 86(A) CH,:CMe*CH,*CH,*[U],*CH:CMe*CH:CH,(B) CH,:CH*CHMe*CH,*[U],*CH:CMe*CH:CH,(C) CH,*CMe:CH*CH,*[U],*CH:CMe*CH:CH,On ozonolysis such substances should yield not only large quantitiesof laevulaldehyde, laevulic acid, and lzevulic acid peroxide, but smallquantities of one or more of formaldehyde, pyruvaldehyde, acet -aldehyde or the corresponding acids, etc.The recognition of these end groups and their accurate quantit-ative estimation in relation to the quantity of laxtilaldehyde and thederivatives thereof formed at the same time would give definiteinformation concerning the non-cyclic nature of the polymeride, itsmolecular weight, and the mechanism of its formation.A newattempt to identify and estimate the ozonolysis products of caout-chouc 87 has demonstrated the formation of the laevulic series ofproducts to an extent corresponding to nearly 90% of the carbonskeleton of the polymeride; in addition, small quantities of aceticacid, acetone (regarded as an impurity), a substance fermentable byyeast, carbon dioxide, formic acid, and succinic acid, have beenrecognised. Now, although none of the minor products can bedefinitely stated to have its origin in an end group, there is littledoubt that at least 2% of the acetic acid produced is a primaryfission product of caoutchouc, and not merely a decompositionproduct of laevulic acid; the origin of the fermentable substance(possibly pyruvic acid) is still in doubt.The statement of Harrieshpopos of the cyclic formula for rubber, that no ozone fission productscontaining less than five carbon atoms were to be obtained, is plainlyill-founded. The question of terminal groups remains open and itssolution awaits further improvement of experimental technique.The polymerisation of many substances is actively catalysed byozonides and peroxides. Ozonised mixtures of two isobutyleneshave been found to accelerate the polymerisation of styrene, indene,py-dimethylbutadiene, and furfuryl alcohol but not of stilbene,R. Purnmerer, G. Ebermayer, and K. Gerlach, Ber., 1931, 64, [BJ, 809;86 G. S. Whitby, Trans. Inst. Rubber Id., 1929, 5, 190.A., 733ORGANIC CHEMISTRY.-PART I. 89o-hydroxybenzyl alcohol, and P-methyl-AP-butene.88 The velocityof polymerisation generally increases with increasing concentrationof the catalyst up to 2% ; moreover the catalytic activity is inherentin the original ozonides, and not in any decomposition products, sincethe activity diminishes rapidly on keeping. The polymerisation ofunsaturated hydrocarbons is strongly accelerated by simultaneouslyoccurring auto-oxidation processes-more effectively, indeed, thanis accomplished by addition of peroxides.89 Probably the actualcatalysts in these cases are primary peroxides which have a morepowerful accelerating action than that of the polymeric peroxidesultimately found among the polymerisation products. Polymeris-ation and peroxide-formation (polymeric) take place side by side,in proportions varying with the chemical constitution of the unsatur-ated compound and the availability of oxygen.When acrylic acid is polymerised by irradiation, non-homogeneous,amorphous products result.Polymerisation is considered to followthe scheme :. * CH(C02H)*CH2 - * - + xCO,H*CH:CH, -+*CH(C02H)*CH2.[CH(C02H)*CH2],, 1*CH(C02H)*CH,*Similarly, irradiation of vinyl acetate in chloroform is stated toyield a product of the type Me-CH( OR)*[CH,*CH( OR)],*CH,*CHCl,.The properties of these polymerides and of polyvinyl alcohols aredescribed.90 Further details are available with respect to theformation of polyoxymethylenes from formaldehyde 91 and it hasbeen shown that polymerisation of aqueous formaldehyde withcalcium hydroxide yields a solution which contains pentoses,hexoses, and possibly some heptose~.~~Nitrogen Compound8.The synthesis of the simple amino-acids and their derivatives hasattracted so large a measure of attention that it is impossible in thespace a t the writer’s disposal to do more than indicate the maingroups of compounds which have formed the subject of investigation.Improved methods of carrying out the Strecker and Kolbesynthesis of a-amino-acids have been described in detail ; 93 methods8 8 R.C. Houtz and H. Adkins, J. Amer. Chern. SOC., 1931, 53, 1058; A.,89 H. Staudinger and L. Lautenschliiger, Annakn, 1931, 488, 1 ; A,, 1031.90 H. Staudinger and H. W. Kohlschutter, Ber., 1931, 64, [B], 2091 ; A.,1270; H. Staudinger and A.Schwalbach, Annakn, 1931, 488, 8; A., 1032.91 H. Staudinger, R. Signer, and 0. Schweitzer, Ber., 1931, 64, [B], 398;A . , 465.92 P. Karrer and E. von Krams, Helv. Chim. ActGT, 1931,14, 820 ; A , , 1037.93 W. Cocker and A. Lapworth, J., 1931, 1391; A., 943.59790 FARMER :for preparing a-amino-acids and a m i d e ~ , ~ ~ N-alkylated p-amino-esters , y- amino-, w -amino -, and various dimet hylamino - andbi~dimethylamino-~~ derivatives of fatty acids have been workedout ; and syntheses of dl-aspartic acidYgg creatine and alacreatine,lserine,2 ethyl aminomalonate and its derivative^,^ derivatives ofl y ~ i n e , ~ and various aminohydroxy- and hydroxyamino-acids 6 havebeen recorded. The formylation of amino-acids,' their acetylationby beten,* and the preparation of glycerol esters therefrom have alsobeen s t ~ d i e d .~A series of investigations by A. Skita and F. Keil and theircollaborators lo deals with the production of the more complexamines by the catalytic reduction of carbonyl compounds in thepresence of simple amines. In most cases colloidal platinum is usedas catalyst. Schiff's bases, or mixtures of the aldehyde and primaryamines from which the bases are formed, yield secondary amines onreduction ; aldehydes of high molecular weight give secondaryamines with ammonia, but the simpler aldehydes yield tertiaryamines. Ketones react usually with aliphatic amines to produceN-substituted imines which are further reducible to secondaryamines : under suitable conditions, however, substantial amountsQp T.Curtius and others, J. pr. Chem., 1930, [ii], 125, 211; A., 1930, 752;H. Krause, Chem.-Ztg., 1931,55, 666; A., 1402; W. Cocker and A. Lapworth,J., 1931, 1894; A., 1402; R. Locquin and V. Cerchez, Bull. SOC. chim., 1930,[iv], 47, 1386; A., 1931, 338; D. M. Birosel, J . Amer. Chem. SOC., 1931, 53,3039; A., 1149; P. S. Yang and M. M. Rising, ibid., p. 3183; A., 1160.95 J. DQcombe, Compt. rend., 1930, 191, 945; A., 1931, 76.Q6 A. Miiller and E. Feld, Monutsh., 1931, 58, 22 ; A., 943.s7 B. Flaschentrgger with F. Halle, T. Hosoda, F. Gebhardt, and B. Blech-man, 2. physiol. Chem., 1930, 192, 245, 249, 253, 257; A., 1931, 76.Q8 V. Prelog, Coll. Czech. Chem. Comm., 1930, 2, 712; A., 1931, 204.Qs M. S. Dunn and B.W. Smart, J. Biol. Chem., 1930,89,41; A , , 1931, 76.H. King, J., 1930, 2374; A . , 1930, 563.S. K. Mitra, J . Indian Chem. SOC., 1930, 7, 799; A., 1931, 205.R. Locquin and V. Cerchez, Bull. SOC. chim., 1930, [iv], 47, 1274, 1252,1287, 1377, 1381; 1931, [iv], 49, 42, 47; A . , 1931, 205, 338, 471.R. Enger and H. Steib, 2. physiol. Chem., 1930,191,97; A., 1930, 1419;R. Enger and F. Halle, ibid., p. 103 ; A., 1930, 1420 ; R. Enger, ibid., p. 117 ;A . , 1930, 1420.W. J. N. Burch, J., 1930, 310; A . , 1930, 460.L. W. Jones and R. T. Major, J . Amer. Chem SOC., 1930,52, 1078; A . ,1030, 754; M. Tomita and J. Karashima, 2. physiol. Chem., 1930, 187, 238;A . , 1930, 585.R. E. Steiger, J. Biol. Chem., 1930, 86, 695; A., 1930, 752.M. Bergmann and F.Stern, Ber., 1930, 63, [BJ, 437; A., 1930, 459.L. Haskelberg, Compt. rend., 1930, 190, 270; A., 1930, 328.lo Ber., 1928, 61, [B], 1452, 1652; 1929, 62, [B], 1142; A., 1928, 1120,1228; 1929, 808; Monatsh., 1929, 53, 753; A., 1929, 1436; Ber., 1930, 63,[B], 34; A., 1930, 327ORGANIC CHEMISTRY.-PART I. 91of primary amines may arise. From diketones and primary amines,N-substituted amino-alcohols can be obtained ; in this way a-phenyl-propane-ap-dione, when reduced together with methylamine, givesephedrine-a method of preparation for the latter which had beenindependently employed by R. H. F. Manske and T. B. Johnson.llTertiary amines are formed by the reduction of nitriles, alone or inthe presence of ketones, and in some cases also by the reduction ofaldehydes admixed with secondary amines.Acylvinyl- and arylvin yl-amines of the general formulaR=CO*CH:CH*NR,R,may be conveniently prepared by the action of ammonium chlorideor the hydrochloride of an amine on the sodium salt of aliphatic andaromatic hydroxymethylene ketones.l2By the action of dry hydrogen sulphide on dry amines (usuallyin ether at 0") M. Achterhof, R. F. Conaway, and C. E. Boord haveprepared a series of amine hydrogen ~u1phides.l~ The salts from themore volatile amines decompose in air, giving sulphur, but thosefrom the less volatile amines suffer oxidation to the correspondingthiosulphates.The structure of sphingosine derived from cerebroside mixtureshas been the subject of renewed in~estigati0n.l~ It is now foundthat, whereas the ozonolysis of triacetylsphingosine yields tetra-decoic acid (and aldehyde) together with a-amino- py-dihydroxy-n-butyric acid, the oxidation of dihydrosphingosine yields palmiticacid; moreover the oxidation of sphingosine sulphate also givestetradecoic acid.It is concluded, therefore, that sphingosine has theconstitution CH,*[CH,],,*CH:CH*CH( NH,)*CH( OH)=CH,*OH.New derivatives of asparaginedialdehyde l5 and hydrazinoprop-aldehyde16 have been obtained and many new examples of theformation of hydrazides, azides, and carbamides of mono- andpoly-carboxylic acids and lactones are furnished by the researchesof T. Curtius and his collaborators.17Muscarine has been successfully purified by the precipitation and11 J .Amer. Chem. SOC., 1929, 61, 580; A., 1929, 441.12 E. Benary, Ber., 1930, 63, [B], 1573; A., 1930, 1026.13 J . Amer. Chem. SOC., 1931, 58, 2682; A., 1041.14 E. Klenk, 2. physiol. Chem., 1929,185,169; A., 1930, 73; E. Klenk andW. Diebold, ibid., 1931, 198, 25; A., 829.1 5 A. Wohl and E. Bernreuther, Annalen, 1930, 481, 1 ; A . , 1930, 1021.16 A. Wohl and A. Pranschke, Ber., 1931, 64, [B], 1381; A . , 937.17 T. Curtius, G. von Briining, and H. Derlon, J. pr. Chem., 1930, [ii], 125,6 3 ; A., 1930, 766; T. Curtius and W. Sandhaas, ibid., p. 90; A., 1930, 757;T. Curtius and H. Sauerberg, ibid., p. 139; A., 1930, 757; T. Curtius, W.Sieber, F. Nadenheim, 0. Hambsch, and W. Ritter, ibid., p. 152; A., 1930,766 ; T. Curtius and W. Dorr, ibid., p.425 ; A., 1930, 75692 FARMER :crystallisation of its salt with the radical [(NH,),Cr(SCN),]- ; analysisof the salt indicates the formula [C,H,,O,$]+ for the muscarine ion.Since muscarine contains a hydroxy-group, gives trimethylamineand dihydroxy-n-valeric acid by the Hofmann degradation, andbehaves as an aldehyde, it is considered to have the constitutionOH*CHEt*CH(CHO)*NMe3*OH or (less probably)CHO CII ( OH ) *CHE t*NMe,*OH. l8Cystine may be satisfactorily reduced to cysteine by the actionof sodium in liquid ammonia,lg by aluminium amalgam in aqueoussolution,20 or catalytically in the presence of spongy palladium.21Treatment of a solution of cystine in dilute sulphuric acid with silversulphate, followed by neutralisation to pH 5-6, causes precipitationof 70--85(70 of the total nitrogen in the form of a compound(C,H50,NSAg),,Ag,S0,.Decomposition of this compound withhydrochloric acid yields a solution containing more than 90% of itsnitrogen in the form of cysteine.22 The silver compound differsfrom the apparently normal silver salt of cystine and is regarded asa silver mercaptide.The question of the ketimine-enamine tautomerism of B-amino-acrylic esters has been examined by K. von Auwers and W. Susemihl 23with the aid of refractivity determinations. Ketimino-forms,because they contain no conjugated system, should display normaloptical behaviour : enamines, on the other hand, with the systemN*C:C*C:O, should exhibit marked exaltation. The optical data,particularly in the case of ethyl p-aminocrotonate and its derivatives,are shown to be in harmony with the constitutionbut cannot be explained in relation to the alternative structuresNHR-CMe:CH*CO,Et ,YHMeNR:CMe*CH,*CO,Et and NH - >CH*CO,Et.Marked differencesare observed between the keto-enolic and ketimine-enamine typesof tautomerism, since in the latter type an equilibrium mixturedependent on the nature of the compound and the external con-ditions does not appear to exist in the molten material in which theenamine form predominates. The conditions which determine thedegree of enolisation in oxygen compounds appear to be little, if atall, active with corresponding nitrogen compounds.18 F. Kog1,H. Duisberg, and H. Erxleben, Annulen, 1931,489,156 ; A., 1279.19 V.du Vigneaud, L. F. Audrieth, and H. S. Loring, J . Anzer. Chem. SOC.,20 E. Gebauer-Fiilnegg, ibid., p. 4610; A . , 1931, 76.21 M. Bergmann and G. Michalis, Ber., 1930, 63, [B], 987; A . , 1930, 754.22 H. B. Vickery and C. S. Leavenworth, J . Biol. Chem., 1930, 86, 129;2s Ber., 1030, 63, [B], 1072; A., 1930, 897.1930, 52, 4500; A., 1931, 76.A., 1930, 754ORaANIC CHEMISTRY.-PBRT I. 93According to A. Hantzsch, a comparison of the ultra-violetabsorption of t ric hloroace t amide , its pi peridine - derivative,CCl,*CO*NC,H,,, and the iminoether CCI,*C( 0Me):NH in methylalcohol, water, and chloroform indicates that the equilibriumCCI,*CO*NH, CCl,*C( 0H):NH is displaced extensively to theright in chloroform and further in water; similarly, benzamideappears to be almost completely dissolved as the iminohydrinPh*C(OH):NH.M Comparison of the boiling points of the amides,methylamides, and iminoethers shows that amides and methyl-amides exist mainly in the iminohydrin form R*C(OH):NH andR-C(OH):MMe.The anomalies in the boiling points of the amidesand methylamides are attributed to association caused by thepresence of the hydroxyl groups and consequent difficulty in passinginto the unimolecular condition. In contrast to the acid amides,thioacetamide appears to be present as the true thioamideCH,*CS*NH, in chloroform or ether and only to a minor extent asthe iminothioether in water.Hantzsch further considers that the two additive productsderivable from hydrogen halides and nitriles are respectively identicalwith the products obtained by the interaction of amides and phos-phorus pentachloride and hitherto regarded as imide chlorides,R*CCI:NH, and amide chlorides, R*CC&-NH,.25 They are actuallynitrilium salts, the former being monohalides [R*C"NH]Cl, and thelatter dihalides [R*CNH]Cl,HCl, in which the second acid moleculeis not structurally combined.Nitriles dissolved in concentratedsulphuric acid are present as completely dissociated sulphates[R*C_IUH]SO,H ; amides also when dissolved by sulphuric acidyield completely dissociated sulphates. Aromatic amides are con-sidered to yield iminohydrinium salts [Ar*C( OH):NH,]SO,H inconformity with the view that the free amides are preponderatinglyiminohydrins, ROC( 0H):NH ; the true tertiary amides, Ar*CO*NR,,however, also yield similarly constituted iminohydrinium salts.The transformation of nitrilium sulphate into iminohydriniumsulphate takes place slowly but completely at the ordinary tem-perature. The conversion of nitrile into amide in aqueous solutiondepends on the formation of nitrilium salts, which pass by additionof water into iminohydrinium salts: these are hydrolysed toamides.A ketenimino-structure is also supposed to be assumed by aceto-nittile in reacting with ethylmagnesium bromide, the product,24 Ber., 1931, 64, [B], 661 ; A., 608.2s Ibid., p. 667; A., 608; compare J.Verhulst, Bull. SOC. chim. Belg.,1930, 39, 563; A., 1931, 47194 FBMER :CH,:C:N*MgBr, reacting with water (addition at the ethyleniclinkage) to yield some aceta'mide.26Saturated nitriles are obtainable in good yield by passing many ofthe members of the fatty acid series, together with ammonia, overheated silica gel.27 New details relating to the preparation of anumber of clp-(cis- and trans-) and py-unsaturated nitriles 28 arerecorded.It is a matter of considerable interest that hydrogen chloride hasbeen found to combine with liquid (or dissolved) hydrogen cyanide,to yield the sesquichloride 2HCN,3HC1; hydrogen bromide andiodide also yield sesquihalides with hydrogen cyanide, but theformation of no such compound as HCN,HCl has been observed.29The sesquichloride, when heated alone or with liquid hydrogencyanide, or when kept in a vacuum over sodium hydroxide, wasfound to yield chloromethyleneformamidine, NH:CH-N:CHCl, ahygroscopic solid: this when heated with quinoline yielded abimolecular hydrogen cyanide-evidently imidoformylcarbylamine,NH:CH*N:C.Mono-, Di- and Tri-saccharides.In last year's Report reference was made to C.S. Hudson'scontention that change of ring form may and does occur during themethylation of sugars, certain of W. N. Haworth's conclusionsrespecting the structural representation of the sugars thereby beingvitiated. The validity of the principle of optical superposition, asutilised by Hudson in arriving at his suggested formulze for certainof the mono- and di-saccharides, has been examined by W. N.Haworth and E. L. E r s t in considerable detail and it is shown thatreliance on the principle in classifying the sugars leads to seriousinconsistencies and necessitates the postulation of structures a tvariance with the bulk of the experimental evidence.30In particular, Hudson ascribes to a-mannose and a-methyl-mannoside a different ring structure from that of p-mannose anda- and p-glucose and their glucosides and tetra-acetates, and assumes26 G.Mignonac and C. Hoffmann, Compt. r e d . , 1930, 191, 718; A., 1930,1564.27 J. A. Mitchell and E. E. Reid, J . Amer. Ch,em. Soc., 1931, 53, 321; A . ,339.28 R. Breckpot, Bull. SOC. chirn. Belg., 1930, 39, 462; A . , 1931, 194; G .Heim, ibid., p. 458 ; A . , 1931, 205 ; P. Colmant, ibid., p. 568 ; A., 1931, 472 ;P. Bruylants and H. Minetti, BuEl. Acad. TOY.Belg., 1930, [v], 16, 1116; A.,1931, 205; P. Bruylants, ibid., 1931, [v], 17, 1008; A . , 1403; P. Bruylantsand L. Ernould, ibid., p. 1027; A., 1403.L. E. Hinkel and R. T. Dunn, J . , 1930, 1834; A . , 1930, 1421.30 J., 1930, 2615; A . , 1931, 200; compare K. Freudenberg, Sitzungsber.Heidelberger Akad. Wiss., 1931, No. 2, 3 ; A . , 825ORGANIC CHEMISTRY .-PART I. 95that the true structural isomeride of p-mannose (and a- and p-glucose,etc.) should be an unknown form of or-mannose having [.ID 4- 77"'since such a value would bring the rotational difference between thisu- and the known p-form into line with those that are found for thetwo glucoses. Hudson's scheme moreover requires that this varietyof u-mannose, and not the normal variety (+ 30")' occurs as acombined residue in 4-glucosido- a-mannose and in 4-galactosido-a-mannose.It has now been conclusively proved by hydrolysis with emulsinthat the mannoside residue in 4-glucosido- and 4-galactosido-a-methylmannoside is the normal pyranoside variety of a-methyl-mannoside and not the hypothetical form of Hudson; 31 moreoverit has been demonstrated that both forms (a- and p-) of methyl-mannoside which are obtainable in the normal manner from mannosehave an identical six-atom structure 32 and that derivatives of4-glucosido- and 4-ga~ac~osido-ma~ose retain unimpaired theirstructural rigidity during methylation.33 From the manner inwhich the optical rotatory power of different methylated lactonesvaries from solvent to solvent there can be little doubt that con-figurational relationships, e.g., the cis- relationship of methoxylgroups in the methylated molecules, have a profound influence onthe optical rotatory powers of substances which cannot alter theirring structure under the infiuence of solvent and are to be lookedto as the source of some of the observed discrepancies in correlatingrotational data.Other demonstrations of the presence of a pyranose structurerefer to penta-acetyl p-d-mann~se,~~ P-methylgala~toside,~~ gly-curonic diisopropylidenegalac t ~ s e , ~ * and 5-met hoxyke tose .39The phenomenon of acyl migration in sugars and polyhydric31 W. N. Haworth, E. L. Hirst, H. R. L. Streight, H. A. Thomas, and J. I.Webb, J., 1930, 2636; A., 1931, 200; W. N.Haworth, E. L. Hirst, (Miss)M. M. T. Plant, and R. J. W. Reynolds, ibid., p. 2644; A., 1931, 200. Com-pare H. S. Isbell, Bur. Stand. J. Res., 1930, 5, 1179; A., 1931, 201.32 W. N. Haworth, E. L. Hirst, H. G. Bott, and R. S. Tipson, J., 1930,2653; A., 1931, 200.s3 W. N. Haworth, E. L. Hirst, and H. R. L. Streight, ibid., 1931, 1349;A., 939; W. N. Haworth, E. L. Hirst, and (Miss) M. M. T. Plant, ibid., 1931,1354; A., 939.34 W. N. Haworth, E. L. Hirst, and J. A. B. Smith, ibid., 1930, 2659; A.,1931, 200.35 P. A. Levene and R. S. Tipson, J. Biol. Chem., 1931,90, 89; A . , 337.36 A. Muller, Ber., 1931, 64, [B], 1820; A., 1039.9 7 J. Pryde and R. T. Williams, Nature, 1931, 128, 187; A., 1036.88 P. A. Levene and G. M. Meyer, J. Biol. Chem., 1931, 92, 257; A.,88 E.F. Hersant and W. H. Linnell, Quart. J. Pharrn., 1931, 4, 52;1276.A , , 82596 FARMER :alcohols has attracted further attention. Certain changes in thepolarity of the acyl group appear to increase the tendency towardsthe formation of cyclic dioxolane derivatives by attracting themobile hydrogen to the CO-group. p-Hydroxyethyl trichloro-acetate, for instance, is unobtainable in the open-chain form : allattempts to prepare it yield the ortho-ester isomerideF*,*O OHIn other instances the strong tendency towards hydrogen migrationfacilitates fission of the acetate molecule into two molecules ofaldehyde on heating, e.g., benzyl trichloroacetate yields benzaldehydeand chloral (CH,Ph.O*CO*CCI, -+ Ph-CHO + CCI,*CHO) .40New examples of the appearance of " y "- or ortho-ester-forms ofsugar acetates have been reported for triacetyl methyl-d-riboside 41and hepta-acetyl 4-glucosidomethylmannoside 42 and migration ofacetyl occurs during the methylation of 2 : 3 : 4-triacetyl a-methyl-glu~oside.~~ The kinetics of acyl migration have been studied forsolutions of 3-acetylisopropylideneglucose by K.Josephson,44 whofinds that a proportionality exists between the rate of acyl migrationand the concentration of hydroxyl ion over a considerable range ofacidity. The '' y "-form of monoacetyl methylrhamnoside, how-ever, is unstable in acid solution and the change whereby theglycosidic methyl group of this compound is hydrolysed, and theacetyl group transferred wholly to Cz, appears to be catalysed byhydrogen ions .45Several interesting observations have been made with regard tothe properties of the free aldehyde forms of sugars and the occurrenceof the aldehyde phase in certain ordinary sugar reactions.Appar-ently the free aldehyde form of galactose is produced in the form-ation bf the phenylhydrazone, since after acetylation the product isidentical with the phenylhydrazone generated from penta-acetylaldehydogala~tose.~~ Also the ring form of glucose oxime wouldseem to open to the aldehydo-form when submitted to the Wohlprocedure for the production of glucononitrile : a t least, hexa-acetylaldehydo-glucose oxime (I) is formed in the process and yieldspenta-acetyl glucononitrile by loss of acetic acid, whereas the cyclic40 H.Hibbert and M. E. Greig, Canadian J . Res., 1931, 4, 254; A., 820.41 P. A. Levene and R. S. Tipson, J . Biol. Chem., 1931, 92, 109;43 H. S. Isbell, J. Amer. Chem. SOC., 1930, 52, 5298; A., 1931, 201.43 W. N. Haworth, E. L. Hirst, and (Miss) E. G. Teece, J., 1931, 2858.44 Ber., 1930, 63, [Bl, 3089; A., 1931, 199.45 w. N. Haworth, E. L. Hirst, and H. Samuels, J., 1931, 2861.46 M. L. WoIfrom and C. C . Christman, J . Amer. Chem. Soc., 1931,53,3413 ;C€€,*O>C<CC1,~A., 938.A,, 1276ORGA.NIC! CHEMISTRY .-PART I. 97hexa-acetyl @-glucose oxime (11) which is produced at the same timedoes not yield the nitrile when heated.47HQ*OAc 1 Ac ( Ac O)N*QHAcsO+ AcO*QH bHQ*OAc QHZNOAc Ho*7JqAcsO+ HO*$?H %GG-AcO*VHH Hw :FJ= CH,*OH CH,*OAcPenta-acetyl aldehydogalactose forms well-defined crystallinecompounds with alcohol and with water.These, unlike the freepenta-acetyl aldehydo-sugars themselves, show mutarotation inalcohol-free chl~roform.~~ The curve for the alcoholate falls rapidlyto a minimum and then increases rather less rapidly to a value higherthan the original ; its form points to the presence in solution of twosemi-acetal individuals in equilibrium with the aldehyde and alcohol :(11.)HT*OAcHQ*OAc(1.)CH,*OAcOH OEtThe aldehydrol, on the other hand, under like conditions shows onlya steady fall in rotation along an exponential curve indicating asimple unimolecular decomposition into free aldehyde and water.Lactose phenylosazone also exhibits mutarotation in methyl alcoholbut not in anhydrous alcohol-free solvents ; the mutarotation ofosazones does not appear to arise from tautomerism betweendihydrazone and azo-forms, since fructose methylosazone, which doesnot possess a labile hydrogen atom, exhibits mutarotation.48~Constitutions have been established, as the result of synthesis,of two natural glucosides : aesculin is formulated as 6-glucosidoxy-7-hydroxyco~rnarin~~ and euxanthic acid as the compound (I) inwhich the sugar residue is glycuronic acid, probably attached to thenucleus by a p-glucosidic linking.50 In addition, the formuhtion ofmonotropitoside (gaultherin) as a primeveroside of methyl salicylate(111) has been synthetically demonstrated.51The aldobionic acid from gum arabic, referred to in last year'sReport, is now shown to be a glycuronosido-galactose in which the4 7 M.L. Wolfrom and A. Thompson, J . Amer. Chem. SOC., 1931,53, 622 ;A., 467.48 M. L. Wolfrom, ibid., p. 2275; A . , 1039.4 h E. VotoEek and F. Vdentin, Arhiv Hemiju, 1931,5, 155 ; A., 1274.49 F. S. Head and A. Robertson, J . , 1930, 2434; A., 1931, 73.50 A, Robertson and R. B. Waters, ibid., 1931, 1709; A., 1040.5 1 Idem, ibid., p. 1881; A., 1400.REP.-VOL. XXVm. 98 FARMER :reducing group of the glycuronic acid residue is joined to the 6-posi-tion of the galactose residue. 52 Sedosan (anhydrosedoheptose) isformulated as the 2 : 7-anhydropyranose (II).538-(R = o-C,H,*CO,Me.)The hexosemonophosphate obtained by R. Robison throughfermentation of glucose or fructose in presence of sodium phosphateis reported to be glucose-6-phosphate, which has now been synthesisedfrom isopropylideneglucose ; 54 methylation of Robison’s productis reported to yield two distinct forms of the corresponding methyl-glycoside.55The saccharals of epimeric sugars prove to be identical, as wouldbe expected : d-glucal is identical with d-mannal, and d-xylal withd-lyxa1.56 It has also been found that tetra-acetyl hydroxyglucalyields the same osazone as tetra-acetyl hydroxygalactal,57 and, byaddition of chlorine, followed by hydrolysis, yields both tetra-acetylglucosone hydrate and triacetyl glucosone hydrate. 58 Bothglucal 59 and +-glucal 6o have pyranose structures, and the latter,which has the double bond in the 2 : 3-position7 constitutes theunsaturated unit in +-cellobial ; the reduction products of +-glucaland $-cellobial, vix., 2 : 3-dideoxyglucose and 2 : 3-dideoxycellobiose,are also pyranose forms.It is suggested as the result of oxidation(hydroxylation) experiments with galactal that the group attachedto the C,-atom in glucals (e.g., OH, OMe, or OAc) may have a direct-ing influence on the spatial disposition of the hydroxyl group which5 2 S. W. Challinor, W. N. Haworth, and E. L. Hirst, J . , 1931, 258; A . ,53 H. Hibbert and C. G. Anderson, Canadian J . Res., 1930,3,306 ; A . , 1930,54 P. A. Levene and A. L. Raymond, J. Biol. Chem., 1930, 89, 479; 1931,5 5 E. J. King, R. R. McLaughlin, and W. T. J. Morgan, Biochem. J., 1931,56 M.Gehrke and F. Obst, Ber., 1931, 64, [ B ] , 1724; A., 1038.57 M. Bergmann and L. Zervas, ibid., pp. 1434, 2032; A., 939, 1275.5 8 K. Maurer and W. Petsch, ibid., p. 2011; A., 1275.59 E. L. Hirst and C. S. Woolvin, J . , 1931 1131; A., 1399.6o 3%. Bergmann and W. Freudenberg, Ber. 1931, 64, [ B ] , 158; A . , 336.465; see Ann. Reports, 1930, 27, 109.1560.91, 751;25, 310; A., 600.1931, 92, 757, 765; A . , 1931, 63, 933, 1148ORGANIC CHEMISTRY .-PART I. 99enters a t the C,-atom, thus being responsible for the predominatingcis- or tmns-dispositions at the C,- and C,-atoms produced inaccordance with the scheme :Alcohols react with acetohalogeno-sugars (mono- or di-saccharides)in the presence of mercuric acetate to produce glycosides of the sugaracetates, the a- or p-configuration of which is to some extentgoverned by the proportions of the reactants.62 By replacing thealcohol with a sugar derivative possessing one free hydroxyl group,the formation of the acetyl derivatives of di- and tri-saccharides canbe effected with some control over the nature (a- or p-) of the glyco-sidic linking.63 A somewhat similar method of coupling, employingsilver carbonate, calcium chloride and iodine in place of mercurysalts, has been applied to the synthesis of tri- and tetra-saccharideacetates.64Recent observations in relation to turanose and melezitose 6 5indicate that these sugars are more correctly represented by thestructures originally assigned to them by G. Zemplkn and G.Braun G6 than by those subsequently assigned by G.C. Anew disaccharide, neotrehalose, synthesised from triacetyl glucose1 : %anhydride and tetra-acetylglucose, appears to be the hithertounknown a-glucosidyl- p-glucoside. 6*Polysaccharides.Indin.-Following the suggestion that glucose may occur as aproduct of hydrolysis of i n ~ l i n , ~ ~ it has been pointed out that the61 P. A. Levene and R. S. Tipson, J . Biol. Chem., 1931,93, 631 ; A., 1400.62 G. ZemplBn, Ber., 1929,62, [B], 990; A., 1929, 683; G. Zemplh andZ. S. Nagy, ibid., 1930,63, [B], 368 ; A., 1930,456 ; G. Zemplh, ibid.,p. 1820;A., 1930, 1167; G. Zemplh and A. Gerecs, ibid., p. 2720; A., 1931, 72.63 G. Zemplbn, Z. Bruckner, and A. Gerecs, ibid., 1931, 64, [ B ] , 744;A., 716; G.Zempldn and A. Gerecs, ibid., p. 1545; A., 1039; G. Zemplbnand Z. Bruckner, ibid., p. 1852; A . , 1040.64 B. Helferich and R. Gootz, ibid., p. 109; A . , 337.6 5 E. Pacsu, J . Amer. Chem. SOC., 1931, 53, 3099; A., 1149.66 Ber., 1926, 59, 2230; A . , 1926, 1229.6 7 J . , 1927, 588; A., 1927, 450.68 W. N. Haworth and W. J. Hickinbottom, ibid., 1931, 2847.60 Ann. Reports, 1929, 28, 102100 FARMER :iodine value of the acid hydrolysis product of inulin is compatiblewith a glucose content in inulin of 5y0.7* Recent experiments ofR. F. Jackson and E. McDonald, however, show that inulin fromdifferent sources (members of the family Composita?) gives onhydrolysis with acid about 92% of fructose, 3% of glucose, and 5%of a group of refractory difructose anhydride^.^^ This group ofdisaccharides is stated to be invariably a constituent of inulinregardless of the plant from which the inulin is extracted or of thedegree of purification to which the inulin is subjected.Sincepolysaccharides related to inulin do not yield the disaccharides, it isconcluded that the latter form an integral part of the inulin moleculeand are not produced by side reactions occurring during hydrolysis.The occurrence of the disaccharides in such constant proportionsregardless of the source of the inulin or of its degree of purificationis taken to indicate that inulin is essentially a homogeneous sub-stance; in other words, it is composed of similarly constructedmolecules, each of which contains the refractory difructose residues.The whole molecule must then contain not less than 110 hexoseresidues, which upon condensation and loss of 110 mols.of water,would produce a polysaccharide having the molecular weight 18,000(compare E. Berner’s value of 3,500 and H. D. K. Drew and W. N.Haworth’s value of not less than about 4,000).Three crystalline difructose anhydrides have been isolated byJackson and McDonald which differ from the anhydrofructoseisolated by J . C. Irvine and J. W. Stevenson.72 A new difructoseanhydride acetate has been derived by the action of inulinase oninulin,v3 but the corresponding difructose anhydride is not as yetknown to be different from all the compounds of Jackson andMcDonald.It is suggested that inulin-bearing plants contain a series ofpolysaccharides of varying complexity which culminate in inulinitself.71 As the series is ascended there is a diminishing ratio ofglucose to fructose until inulin is reached.In the dahlia the develop-ment of the more complex members of the series has proceeded tosuch an extent that inulin is the predominating polysaccharide : amore nearly complete elimination of glucose is therefore to beexpected in the dahlia inulin than in that of plants which appear tohave less ability to synthesise inulin.‘O 13. Pringsheim, J. Reilly, and others, Ber., 1930, 63, [B], 2636; A . , 1930,7 1 Bur. Stand. J. Res., 1930, 5, 1151; 1931, 6, 709; A., 1931, 202,72 J . Amer. Chem. Soc., 1929, 51, 2197; A., 1929, 1046.1562.827.H. Pringsheim and W.G . Hensel, Ber., 1931, 64, [B], 1431 ; A., 941ORGANIC CHEMISTRY.-PART I. 101Lc~vun.-H. Hibbert and his collaborators 74 accept the view thatin the growing plant glucose units which later unite to form starchand cellulose are convertible, to a considerable extent, into fructosewith the resulting formation of l z v u l ~ s a n s . ~ ~ The wheat plant,after growing spikes, contains in its stem an alcohol-insolublesubstance which yields a large amount .of fructose; immaturewheat grains, however, contain 6% of laevulosan and an equalpercentage of starch; as maturity approaches, starch is formed inincreasing quantities (50-60 yo) while lzvulosan gradually falls toabout 0.4%. The presence of these polymerised anhydrofructoses(lzemlosans) is held not to be confined to any group of plants : onthe contrary, their occurrence is widespread and the existence of anumber of polymerides intermediate between fructose anhydride andinulin is to be expected.Although various observers agree that bacteria can synthesiselaevulosans from sucrose, and, indeed, new preparations of lzevanfrom sucrose have been obtained by the action of B.mesentericusand B. ~ubtilis,~~, 76 no case appears to have been recorded in whichbacterial action has produced a lzevulosan from glucose, as appearsto occur in the plant. Lzevan is apparently produced only fromthose sugars containing the furanose ring of fructose. Theproduct obtained by employment of B. mesentericus gives a 97%yield of fructose; it also gives a triacetate differing markedly fromthat of inulin, and a trimethyl derivative which gives 1 : 3 : 4-tri-methylfructofuranose on hydrolysis.The polysaccharide appearsto be built up from the anhydro-fructofuranose unit with linkingsat positions 2 and 6 of the fructose chain and is probably to berepresented : 74HO H HO H HO HCH,-0The hydrolysis of laevan with 0-1N-oxalic acid at 65" proceeds a tapproximately the same rate as that of sucrose and inulin.77Starch.-The view that natural starch is composed of amylopectinand amylose is not generally accepted. These substances arereported to be formed by the successive depolymerisation and74 H. Hibbert, R. S. Tipson, and F. Brauns, Canadian J. Res., 1931,4,221;75 H. Colin, Bull. SOC. Chirn. biol., 1925, 7, 173; A., 1925, i, 618.7 6 H.Hibbert and F. Brauns, Canadian J . Res., 1931,4, 596; A., 1276.7 7 H. Hibbert and E. G. V. Percival, J. Amr. Chem. SOC., 1930, 52, 3996;A., 827.A . , 1930, 1661102 FARMER :repolymerisation of natural starch, and their distinctive character-istics to arise from differences in physical character or from admixturewith other substances. '8 A substance containing both phos-phorus and nitrogen is reported to be present in potato- and wheat8-starch, combined with the polysaccharide by means of a radicalcontaining phosphorus ; the bulk of both phosphorus and nitrogencan be extracted, the characteristics of the starch becoming some-what changed in the process. The phosphorus content of certainpotato-starch degradation products has been found to attain a valuebetween that corresponding to a disaccharide-H3P0, and a tri-saccharide-H3P0, aggregate.79W. N. Haworth and E. G. V. Percival have shown that the biosederivable by degradation of trimethylamylose with acetyl bromidecontains two glucopyranose units and conclude that the essentialstructure of the original polysaccharide comprises maltose residuesjoined to form a chain of a-glucopyranose units thus : 80Treatment of anhydrous maltose with hydrofluoric acid is foundto give a polymeride (maltan) which is indistinguishable from asimilar substance (amylan) obtainable from anhydrous potato-starch by the same treatment.81 The isolation of various newamylosans is reported.S2The glycogens obtained from different sources are stated to beidentical, observable distinctions being attributed to differences inthe degree of polymerisation and of esterification with phosphoricacid.83 Degradation experiments carried out with trimethylglycogen show that glycogen is undoubtedly constituted on the samegeneral plan as starch and consists largely of a-glucopyranoseresidues joined in a continuous chain as shown for starch above.8078 J. Effront, Ann. Xoc. Zymol., 1930, 2, 1; A., 1931, 469; S . von Naray-Szab6,Z. physikal. Chem., 1930,151,420; A., 1931,202. Compare M. Samec,E. Pehani, and J. Stojkovib, Kolloidchern. Beih., 1931, 33, 103; A., 941. '' M. Samec and W. Bendger, Kolloidchem. Beih., 1931, 33, 95; A . , 941;M. Samec, S. Seligkar, and V.Zitko, ibid., p. 449; A., 1277.8o J . , 1931, 1342; A . , 941.B. Helferich, A. Starker, and 0. Peters, Annalen, 1930, 482, 183; A . ,1931, 74.82 H. Pringsheim, A. Wiener, and A. Weidinger, Ber., 1930, 63, [B], 2628;A., 1930, 1561 ; H. Pringsheim, A. Weidinger, and P. Ohlmeyer, ibid., 1931,64, [B], 2125; A . , 1277.83 K. M. Daoud and A. R. Ling, J . SOC. Chem. Id., 1931, 50, 365, 379;A., 1277ORGANIC CHEMISTRY.-PART I. 103Cellulose.-Further considerations relating to the molecular sizeof cellulose as deduced from viscosity measurements have been putforward by H. Staudinger and 0. Schweit~er.~~ The viscosity ofsolutions of purified cotton in Schweitzer’s reagent diminishes withtime without becoming constant after four weeks, the change depend-ing on the oxidative degradation of the macromolecules of thecellulose by copper oxide.Calculation of the molecular weight ofcellulose from the viscosity of its solutions in Schweitzer’s reagentshows that a more or less profound degradation of the moleculeoccurs according to the method of purification. The highestobserved value (190,000) is for purified cotton ; slight degradationaccompanies mercerisation. Sulphite-cellulose and copper-silk aremore appreciably affected (mol. wt. 80,000-65,000 and 35,000respectively).The general trustworthiness of Staudinger’s procedure in applyingthe measurement of viscosity to the determination of the molecularweight of cellulose and its derivatives is, however, questioned byK. Hess and his co11aborators,*5 who point out that the viscosimetricproperties appear to be dependent on fibre purification (and accom-panying disorganisation), during which foreign matter having agreat influence on the viscosity is removed.Treatment of the fibrewith 2% caustic soda and dilute hypochlorite solution, for example,is stated to remove a, non-cellulose material localised on the outerlayers, and a further component is removed by chlorine dioxide.Other workers as a result of a study of the action of dilute acids oncellulose have regarded the latter as a mixture of a crystalline phase(the source of polysaccharides) enveloped in an amorphous skinwhich is destroyed under more or less drastic conditions.s6It is contended, however, that the viscosity method is justified bythe complete analogy which exists between the behaviour of thesesubstances and that of synthetic, highly polymerised compounds.87With both synthetic and natural products, deviations from theHagen-Poiseuille law become more marked with increase in mole-cular weight and more noticeable in concentrated than in dilutesolution. They are not observed in very dilute solution (sol solution)in which the molecules have freedom of movement. It is main-tained that diminution of the viscosity of cellulose solutions withincreasing purification of the preparations is not due to the removal*4 Ber., 1930, 63, [B], 3132; A., 1931, 202.85 K. Hess, C. Trogus, L. Akim, and I. Sakurada, ibid., 1931,64, [B], 408;A., 469; K. Hess and I. Sakurada, ibid., pp.1174, 1183; A., 828; compareK. H. Meyer and H. Mark, ibid., p. 1999; A., 1276.86 Bouchonnet, Jacquet, and Mathieu, Bull. SOC. chim., 1930, [iv], 47,1266; A., 1931, 202.8’ H. Staudinger, Bet-., 1931, 64, [B], 1688; A., 1040104 ORGANIC CHEMISTRY.-PART I.of incrusting matter, but to the degradation of the sensitivemacromolecules.Formaldehyde appears to have an important influence on cellulosewhen applied in mercerisation operations with sulphuric acid or inthe action of acetic anhydride-acetic acid mixture at 100°.88 I nthe former case the fibres are protected and an enhanced affinity forsubstantive dyes is conferred, and in the latter the action of the acidmixture is retarded, the fibres are rendered immune to substantivedyes, and their property of linear swelling on treatment with sodiumhydroxide solution is modified. It is suggested that the formal-dehyde can so modify (immunise) the cellulose that the specificaction of sodium hydroxide (cellulosate formation) is excluded.The action of the formaldehyde is conceived to result in the form-ation of hydroxymethyl ethers of cellulose : I_',C*OH + CH20 +h3OCH,*OH I or + (zC=O),CH,.Questions relating to the adsorption of sodium hydroxide bycellulose are considered by S.Liepatov and N. Sokolova 89 and byG. Champetier.gO The last author demonstrates by a titrationmethod the formation of the compounds (C6H,005)2,NaOH,(C6HI0O 5) ,,2NaOH, ( C6H lo0,),,3NaOH, and C6H ,,,o ,,NaOH insolutions containing 10 to 60% of caustic soda.The interactionof sodium with cellulose in dry liquid ammonia a t its boiling pointyields rapidly the monosodio-derivative (1Na : lC6H1005), thetheoretical amount of hydrogen being evolved ; further reaction isthen slow, but yields eventually the Na,-deri~ative.~lIt is possible by use of mixtures of phosphoric acid and nitric acidto obtain cellulose nitrate preparations (free from phosphate-nitrateesters) corresponding in nitrogen content to the pure trinitrate( 14.14y0 N).92 The process is accompanied by swelling of the fibres,which facilitates access of acid to the interior of the material andthus ensures uniform action. Nitration effected in this way isrelatively slow, the nitric acid mercerising the cellulose beforeesterification commences.With other nitrating mixtures, only thenitric acid is active as an esterifying agent, but the maximum degreeof nitration always falls short of the pure trinitrate.93Degradation of cellulose to the triose, tetraose, and hexaose stageshas been accomplished by partial hydrolysis with very concentrated88 M. Schenk, Helv. Chim. Acta, 1931, 14, 520; A., 717.89 2. anorg. Chern., 1930, 192, 383; A., 1930, 1562.Compt. rend., 1931, 192, 1593; A . , 941.91 P. C. Scherer, jun., and R. E. Husser, J . Amer. Chem. SOC., 1931, 53,2344; A . , 1041.s2 E. Bed and G. Rueff, Ber., 1930, 63, [B], 3212; A., 1931, 203; Cellulose-chem., 1931, 12, 53; A., 606; C. Trogus, Ber., 1931, 64, [B], 406; A., 409.93 R. C. Farmer, J . SOC. Chem. Id., 1931, 60, 75; A., 717ORGANIC CHEMISTRY.-PART II.105hydrochloric acid,w and to the tetraose and hexaose stages byhydrolysis of appropriate acetate fractions by Zemplbn’s method.95Similarly, methylation of acetone-soluble cellulose acetate, followedby the acetolysis, deacetylation, and further methylation of thederived trimethyl cellulose, has yielded decamethyl P-methylcello-trioside and a methylated cellodextrin which is possibly a cello-tetraose deri~ative.~6E. H. BARMER.PART II.-HOMOCYCLIC DIVISION.Tautomerism.(Continuedfrom Ann. Reports, 1929, 26, 116.)Prototropy.-Triad systems. The first clear case of three-carbonprototropic change in a system of the type NR,GH:CH*CH,*NR’,,in which covalency changes beyond the limits of the system itselfare structurally excluded, has been investigated by C.K. Ingoldand E. R0thstein.l The previous case examined by these authorswas complicated by superimposed anionotropic changes. The iso-meric bis-quaternary salts (I) and (11) have now been prepared andtheir individuality as separate, structural isomerides has beenproved. In the presence of moderate concentrations of hydroxideor alkoxide ions, however, they undergo facile prototropic inter-conversion :8 @8 e 8 { NEt,*CH,*CJXCK*h!teEt,}X, e { NEt3*CH:CH*CH2*beEt,} g2(1.1 (11.)Since the hydroxy- and methoxy-derivatives of the type{ $R3*CH2*CH (OR”) *CH,-gR ’, } g2(R” = H or Me)‘could not be converted by ordinary reagents intothe unsaturated derivatives, the possibility that interconversion ofthe latter is preceded by addition of water or alcohol to the doublelinking (as in the case of the diisobutylenes) is excluded.Finally,it should be noted that, whereas the unsymmetrical glutaconicesters often do not maintain their individuality as separate isomer-ides,3 the bis-quaternary propene derivatives have separate indi-94 L. Zechmeister and G. Toth, Ber., 1931, 64, [B], 854; A., 716.86 F. Klages, ibid., p. 1193; A., 827.96 W. N. Haworth, E. L. Hirst, and H. A. Thomas, J . , 1931, 824; A., 941.1 J., 1931, 1666; A., 1042.8 F. Feiat, Anlzalen, 1922, 428, 26, 61, 71; A., 1922, i, 621, 653.Ann. Reports, 1929, 26, 119.D 106 BAKER AND BENNETT :vidual existence. This is in agreement with the view4 that themore strongly m-directive NR, group is less effective in promotingprototropic mobility than is the more weakly m-directive GORgroup because, unlike the latter, it cannot provide a seat for theanionic charge.isfurnished by the conversion of 1 : 2- into 2 : 3-diphenylindene underthe influence of ethoxide ions.,Important light on the conditions governing mobility andequilibrium in the ay-diphenylmethyleneazomethine (A) and di-phenylpropene (B) systems has been obtained by C.W. Shoppee.78A further example of the mobility of the indene structurekl(111.1 p-C,H,R*CH:N*CH,Ph G C,H,R*CH,*N:CHPh (IV. Akap C ,H,R*CH:C( CO,E t)*CH,Ph s C,H,R*CH,*C( CO,E t):CHPh B(V.) WI.)The following table summarises the data obtained :@- 0.054 0.557 6.82 - 7.09 7.83 0.322 Ak,+k, (hr.-') { - <<0.060 0-058 0.39 - 0.64 1.02 - B0.149 0.370 0.887 (1.0) 1.08 1.13 1.23 A rZl - 0.77 - - 0.85 1.00 1-08 BR ...............NR,. NMe,. OhIe. I. (H.) Br. GI. Me........................................... K87.0 73.0 63.0 (50.0) 48.0 47.0 45.0 A - 56.5 - - 54.0 50.0 48.0 B ...... Equilibrium % of {p ,;;Dipole moment of C,H,R,e.8.u. x 10-1* ............ - +1*39 -0.80 -1.25 - -1.51 -1.56 +0.50Mobility clearly runs parallel to the inductive (-1) effect, increasingin the order p-NMe,<Me<OMe<Hal., and is thus obviously de-pendent on the ease of ionisation of the proton. On the other handthe simple view that equilibrium is controlled solely by the relativestability of the electromeric forms of the ion * cannot be main-tained, since, interpenetrating a series of groups of the polar typeI (NR, and Me) which in themselves are correctly arranged, isa series of groups (NMe,, OMe, Hals.) of the polar type - I + T,the expected order of which is completely inverted.Analysis ofthe system (111) s ion e (IV), in which the concentrationof the intermediate ion is presumed to be small, shows that theequilibrium constant K = v1/v2/v3/v4 = ~ 1 / ~ 4 / v z / v 3 , that is, it is the@2'1 %Va 2'4H. Burton and C. K. Ingold, J . , 1928, 904; A., 1928, 634.Ann. Reports, 1928, 25, 119.A. Garcia Banh and F. Calvet, Anal. Pis. Quim., 1929, 27, 49; A . , 1929,688. ' J., 1930, 968; 1931, 1226; A., 1930, 912; 1931, 834.Ann. Reports, 1927, 84, 106ORGANIC CHEMISTRY.-PART II.107ratio of the ratios of the rates of ionic dissociation (facilitated by- I and - T and retarded only by + I effects) and ionic associa-tion (facilitated by + I and + T and retarded only by - I effects).Hence equilibrium, as opposed to mobility, involves two rate-affecting phases which partake of the nature of side-chain reactionsof the opposite types. By analysis of his results the author showsthat, as in cyanohydrin f~rmation,~ the co-existence of two antagon-istic processes of control must be assumed, and, since it is shownthat it is the + T effect which is important, this process of duplexcontrol must apply to a stage in which the external reagent iselectron-seeking, that is, to the reassociation stage, which is thusof fundamental importance in controlling the equilibrium.Thus inethe electromeric ion C,H,R*CH*N*CHPh in which the anionic chargeis distributed between C, and C,, recombination of the proton willoccur preferentially at C, either if R strongly attracts electrons(- I , absorption of charge on C,) or if it strongly repels or releasesthem easily (strong + I + T ; the charge developed on the carbonatom para, to R repels electrons from Ca to C,,) ; but if R repels orreleases electrons only slightly (weak + I + T), the tendency forthe aromatic ring to absorb the charge on C, may be frustrated,causing ppeferential recombination a t this point.In making use of data derived from the orient-ing effects of groups in aromatic substitution as a practical criterionof their polar effect in prototropy, care must be taken not to deduceI effects, which constitute a permanent polarisation of the mole-cule, by the purely mechanical inversion of & T effects representingmainly a polarisability called into play only at the demand of thereagent.Thus, whereas benzene hydrogen substitution demandsavailability of electrons a t the point of reaction and is thereforefacilitated by + I and + T effects and retarded only by - 1effects, prototropy depends on the positivity of the field at the seatof ionisation and is therefore facilitated by - I and - T effectsbut retarded only by $- I effects. Hence, retardation of benzenehydrogen substitution does not run parallel with facilitation ofprototropy unless electromeric effects of either sign are structurallyimpossible.As C. W. Shoppee l1 has pointed out, it does notfollow that, because a p-carbethoxy-group (- 2') tends to stabilisethe py-phase in the system citraconic-itaconic esters,l2 a P-methylgroup (+ I ) should therefore stabilise the ap-phase. ConsiderationA. Lapworth and R. H. F. Manske, Ann. Reports, 1928, 25, 147, andref. 27.a YPentad systems.l1 J., 1930, 968; A., 1930, 912.l a Ann. Reporb, 1927,24, 113108 BAKER AND BENNETT:of the two enolide ions in the critical stage shows that the - Teffect of the p-carbethoxy-group (b b,) acts on displaceable double-bond electrons, inhibiting a3. The + I effect of the p-methyl group(c) acts on the p-carbon, charging it negatively and directing theQR bcr, OR4.A- &I >c==c-c-c-0Y l V S VJ IORelectrons away from a2 into the alternative route a ; since a3 dependson initiation from a2 (which in turn depends on a), the + I effect(c) will also indirectly inhibit a3. Hence, in accord with experimentalresults,13 the methyl group, like the carbethoxy-group, should favourrecombination of the proton at C, with consequent stabilisation ofthe py-phase.Further results of G. A. R. Kon and R. P. Linstead and theirco-workers indicate that some factor other than the purely polarmust affect the position of equilibrium in such systems.14 The resultsobtained for a series of acids of the type CHR1R2*CR3:CR4*C02Hin N-sodium ethoxide at 25" are as follows : l5% aP-Form at yo a#l-Fom atRIR2.R3. R4. equilibrium. R1R2. R3. R4. equilibrium.H, H H 100 EtMe H H 23Me H 100 MeH Et H 21 ZiH Me H 33 MeH Et Me 50E t a Me Et 57 EtH PP H 33Me, H H approx. 10 ** In the case of the isohexenoic acid the quantitative results are onlyapproximate owing to the complication introduced by the addition of alcoholto the aP-ester, which reaction is appreciably faster than the tautomericchange.Here the qualitative effect of a-, P-, and y-alkyl substituents followsthe lines expected from theory.16 More difficult to interpret is theeffect of a substituent methyl group on the position of equilibriumin cyclohexylidene- and cyclopentylidene-acetic acids and the corre-sponding methyl ketones. Pure dry cyclohexylidene- and cyclo-l3 A. A. Goldberg and R.P. Linstead, J., 1928, 2343; A., 1928, 1214.14 Compare Ann. Reports, 1927, 24, 112.1 5 Ann. Reports, 1927, 24, 111; R. P. Linstead, J., 1930, 1603 ; 1929, 2498;A,, 1930, 1162, 64; R. P. Linstead and J. T. W. Mann, J . , 1,930, 2064; A.,1930, 1405; G. A. R. Kon, E. Luton, R. P. Linstead, and L. G. B. Parsons,J., 1931, 1411 ; A., 934.Ann. Reports, 1927, 24, 111ORGANIC CHEMISTRY .-PAR,T II. 109hexenyl-acetic acids are interconvertible in carbon dioxide at 150°,17the proportion of the py-form (83%) in the equilibrium mixtureclosely approximating to that (88%) observed when equilibrationis effected in sodium ethoxide. The position of equilibrium issimilar in the case of the corresponding cyclopentylideneacetic acid,although mobility is much greater.l8 The effect of a- and ringsubstituent methyl groups in the systems (CH,), >C:CH*COR issummarised in the following table : l9Acids (R = OH).Ketones (R = Me).r- A \ -7 9; CCB-FOW % aP-FonnSubstituent. at equili- Mobility, at equili- Mobility,Ring. a*. brium. 10 ( k , + k , ) hr.-l. brium. lo4 (k,+k,) min.-l.n = 5- H 12 1 43 700- Me 32 0.0075 02-Me H 11.5 0-15 03-Me H 9 0.27 25 -4-Me H 7 0.42 13.5 600-700--n=4- H 14 22 84 ca. 3000- Me 38 0.58 64 3000Thus, although, as would be expected, introduction of a methylgroup in the a-position causes a marked shift in the equilibriumtowards the ap-form and a strong retardation of mobility in bothacid series, the reverse effect is observed in the ketone series, similarsubstitution here favouring the py-phase, the effect on mobilitybeing much less marked.In the cyclohexene acid series nuclearmethylation causes a slight displacement (4>3>2) in favour of thepy-phase, and a similar small decrease in mobility, whilst in thecorresponding ketone system introduction of a methyl group inposition 2 stabilises the &-form to the almost complete exclusionof the a@-form, similar substitution in position 3 or 4 exerting nopronounced effect .The more facile mobility of the system >CH*CO*OR =+> C:C( OH)*OR compared with that of its extended pentad-enolform >CH*C:C-CO*OR =+ >C:C*C:C(OH)*OR 2o is illustrated byresults obtained by W. E. Hugh and G. A. R. Kon.21 Ethyl cyclo-pentylidenemalonate is converted by sodium ethoxide into thesodio-enol.Weak acids such as benzoic are able to catalyse only17 R. P. Linstesd, J., 1930, 1603; A., 1930, 1163.l* Compare Ann. Reports, 1929, 26, 118.19 G. A. R. Kon and R. S. Thkur, J., 1930, 2217; A., 1930, 1582.20 Ann. Reports, 1927, 24, 109.2 1 J . , 1930, 776; A., 1930, 773110 BAKER AND BENNETT :the keto-enol change and not the less facile three-carbon tauto-merism and the product contains 30--50% of the py-ester.OEt OEtHCH,*CH,I \C*CHdH,-CHNContrary to the authors’ previous suggestion22 that the cyclo-hexane ring exerts a special attraction for the double linking, similartreatment of ethyl cyclohexylidenecyanoacetate causes no conversioninto the py-form, nor was any such conversion observed in the caseof ethyl a-c yano - p - et hylcinnamat e or of ethyl a-cyano- y-phenyl-P-methyl-Aa-butenoate.I n these cases, however, the system isterminated by the combination <gz2R, which is probably moreeffective in promoting mobility than is the group <COzR.23 Thecyano-group will tend to absorb the charge on Ca,24 thus promotingreassociation of the proton a t C, with a consequent stabihation ofthe crp-form. Moreover, in ethyl a-cyano-p-ethylcinnamate thephenyl group in the p-position will activate Cy towards a proton25and thus further displace equilibrium in favour of the ap-phase.R. P. Linstead26 attributes the effect of p- and y-phenyl sub-stituents to an element of stability associated with conjugatedsystems, termed the “ Thiele factor ” by A.Lapworth and R. H. F.Man~ke.~’ The latter authors regarded this as not necessarily ofa polar nature : R. P. Linstead asserts that it is non-polar, but theview that the phenomenon is essentially of a polar nature seemsequally tenable and undoubtedly of more value in correlating alarge number of experimental facts.The Glutaconic Problem-Some years ago a study of the additionof cyanoacetic esters to glutaconic esters led E. P. Kohler andCO R22 G. A. R. Kon and E. A. Speight, Ann. Reporb, 1927,24, 113.23 Ibid., 1927, 24, 110.24 J. W. Baker, K. E. Cooper, and C . K. Ingold, dbid., 1928, 25, 138.25 Ibid.,p. 146.26 J., 1929, 2498; A., 1930, 64.27 J., 1928, 2535; A., 1928, 1246ORGANIC CHEMISTRY.-PART 11. 111G. H. Reid28 to the conclusion that these reactions proceed aswould be expected with ap-unsaturated esters, the results lendingno support to the conception of a " normal " form of the glutaconicesters having a symmetrical formula and a capacity for additionin the 1 : 3-positions.The whole subject is now being re-examined in the South Ken-sington laborat~ries.~~ The resolution of " normal '' ocy-dimethyl-glutaconic acid into optically active forms 30 points directly to theunsymmetrical structure CO,H*CMe:CH*CHMe*CO,H.A carefulexamination of the tautomerism of some cyanoglutaconic estersby G. A. R. Kon and H. R. Nanji has led to the isolation of both theAa- and the AB-isomeride of ethyl a-cyano- py-dimethylglutaconate,C0,Et *C( CN):CMe*CHMe*CO,Etand CO,Et*CH( CN)*CMe:CMe*CO,Etand the proof that both the " normal " and the labile form describedbefore 31 consist of the equilibrium mixture arising from the catalyticaction of sodium ethoxide on the Aa-ester.These results are in fact adequately explained without the specialassumption of a " normal " form, and the view that the isomerismof the glutaconic acids and their derivatives is due to the occurrenceof three-carbon tautomerism together with cis-trans isomerism will,no doubt, now be generally accepted.This was substantially thecontention of F. F e i ~ t , ~ , who, however, seems to have over-emphasised the single factor of cis-trans isomerism, regarding thethree-carbon systems as always dynamic. In actual fact, where acrystalline substance is isolated, a static formula must be assignedto it, and both structural and steric isomerism may be expectedto occur.In an investigation of some substituted glutaconic esters fromthis point of view G.A. R. Kon and E. M. Watson find that twoforms of the ester of a-benzyl-p-methylglutaconic acid arise, shownby ozonolysis to be structurally isomeric. These are found to bethe cis-ap- and the trans- py-isomeride : the remaining stereoisomer-ides (trans-ap and cis-py) have not yet been isolated.33Two anomalous cases still remain which have hitherto beenregarded as evidence of the " normal, " form of glutaconic acids.28 J . Amer. Chem. SOC., 1925, 47, 2803; A., 1926,48.29 J . , 1931, 1011.30 T. H. McCombs, J. Packer, and J. F. Thorpe, ibid., p.547; A., 604.31 J., 1931, 660; A., 608; compare N. Bland and J. F. Thorpe, J., 1912,82 LOC. oit., ref. 3.33 J., 1932, 1.101, 871 ; Ann. Reports, 1912,9, 86-89112 BAKER AND BENNETT :The first of these is the isolation,3* from the products of the reactionof ethyl sodioc yanoacet ate with ethyl p- hydroxyglutarate (whichunder the experimental conditions gives “ nascent ” ethyl glutacon-ate), in addition to the expected 1 : 2-additive product, of a smallproportion of ethyl cyclopentanone-2 : 4-dicarboxylate (hydrolysed tocyclopentanone-3-carboxylic a~id).~5 This must be produced bycyclisation of ethyl cc-cyano- p-carbethoxyadipate apparently formedby 1 : 3-addition :-yH*CO,Et TH( CO,Et)*CH( CN)*CO,Et,-CH*CO,Et+ 7%CH,*CO,EtCH(CO,Et)*CH, 1 \C:NH --+CH,-CH( C0,Et )/TH2CH( C0,H)-CH,I \co I CH,- CH,/It should bb noted, however, that in ethyl glutaconate a stronglypolar carbethoxy-group is present on each side of the double linking,with a methylene group intervening on one side only.Hence, justas the addition of iodine chloride to a double bond occurs in bothsenses, only the major product being in accord with Markovnikov’srule,36 the by-product in the above reaction may possibly be due,not to 1 : 3-addition, but to reversed 1 : 2-addition :GH*CO,EtCH*CH,*CO,Et CH,*CH,*CO,Et - QH (C02E t ) *CH ( CN)*CO,E tIf this explanation is correct, there only remains the second anomaly,namely, the reported isomeric forms of the ester of 3-methylcyclo-propene-1 : 2-dicarboxylic acid.37 Some explanation of this willno doubt soon be found.Transannular Tautmerism.--The isolation of two transannular(also termed transannelar) isomeric hydrocarbons is described byE.Bergmann.3s Benzhydrylideneanthrone is converted by phenyl-magnesium bromide into 10- hydroxy- 1 O-phenyl-9- benzhydrylidene-9 : 10-dihydroanthracene, which is reduced by sodium formate andformic acid to a mixture of 10-phenyl-9-benzhydrylidene-9 : 10-dihydroanthracene and 10-phenyl-9-benzhydrylanthracene. Thelatter is converted into the former through its sodium derivative.3 p C. K. Ingold and J. F. Thorpe, J., 1921, 119, 492.3s F. W. Kay and W. H. Perkin, J., 1906,89, 1645.36 A. Michael, J. pr. Chmn., 1899, 60, 450; A., 1900, i, 321.s7 Ann.Reports, 1923,20, 107-110.38 Be?., 1930, 63, [B], 1037; A., 1930, 902ORUANIC CHEMISTRY.-PART II. 113C 6 H 4 < b 6 H 4@‘Ph1I - C6H4<7)C,H,2e CPhc6H4<c>6H4CHPhThe possibility of both prototropic and anionotropic changes in9-arylidene-9 : 10-dihydroanthracene derivatives of type (11) mustbe borne in mind 39 in the interpretation of the results obtained bybromination of 9-alkyl- or 9-aryl-anthracenes, the investigation ofwhich has been continued by E. de Barry Barnett and his collabor-ators. It will be noticed that the intermediate dibromide (IV),which is presumably the initial product in the bromination, can passdirectly by elimination of hydrogen bromide into derivatives oftype (11) or (111), and, when such derivatives are formed, con-ditions governing the mobility and equilibrium of prototropic systemsare obviously involved.Derivatives of type (I), however, cannot[HI’(1.1“l;I?y+ /+ (111.) \BrCHR,\ /Brc6H4</ YC 6 H 4 UV.1H’ ‘Brbe thus directly obtained and their formation indicates that con-ditions governing anionotropic changes must be considered. Inthis respect the effect of cc-chlorine substitution on the brominationof 9-substituted anthracenes is instructive. Bromhation of 4-chloro-9-benzyl- and 4 : 5-dichloro-9-methyl-anthracene affords, respec-tively, 4-chloro-w-bromo-9-benzyl- and 4 : 5-dichloro-9-bromomethyl-anthra-cene 40 (both of type I), which are the stable forms anticipatedin the anionotropic system involved.39Ann. Rep&, 1928,%, 130.40 J.W. Cook, J., 1928, 2802; A., 1928, 1365114 BAKER AND BENNETT 1The following table summarises the effect of nuclear substitutionon the relative proportions of derivatives of types (11) and (111) inthe bromination of various 9-arylanthracenes :Predominant form ofNuclear substituent. RZ. bromination product. .................. Unsubstituted 41 Ph, H I112-Chloro 42 Ph, H I11l-Chloro 43 ........................... Ph, H 70% (11) 30% (111)Unsubstituted 4 5 p-CI*C,H,-, H I111 : 5-DichIoro 45 p-CI.C,H,-, H I12 : 3-Dimethyl 46 Ph, H I111 : 4- ,, 47 Ph, H I1In these cases prototropic change is involved and the effect ofnuclear chlorine-substitution is readily explained by the - I effectof the chlorophenyl nucleus, which, by withdrawing electrons fromthe central nucleus, will tend to stabilise the negative charge ofthe electromeric anion on the nuclear atom Cl0 with the resultant..............................1 : 8- or 1 : 5-Dichloro 44 Ph, H I1 ........................................................................@HR ICHR I1 c:> @ CBrIon-Type (111). Ion-Type (11).preferential (1-chloro-) or exclusive (1 : 5- or 1 : 8-dichloro-) form-ation of derivatives of type (11). The case of 1 : 4-dimethyl sub-stitution is, from this point of view, an0malous.4~Anionotropy.-A study of further examples confirms the con-clusions previously reported 49 relating to the factors affecting thernobiEity of anionotropic systems. Thus in boiling acetic anhydrideboth methylvinylcarbinyl and crotyl trichloroacetates afford thesame equilibrium mixture containing 55% of the former, whilsta-m-4-xylylallyl alcohol is converted into 2 : 4-dimethylcinnamylalcohol by acetylation and subsequent hydrolysis.5O41 J. W. Cook, J., 1926, 2161; A., 1926, 1131.42 E. de B. Barnett and J. L. Wiltshire, J., 1928, 1822; A., 1928, 995.43 J. W. Cook, J., 1928, 2802; A., 1928, 1365.44 E. de B. Barnett, N. F. Goodway, and J. L. Wiltshire, Ber., 1930, 63,46 E. de B. Barnett and J. L. Wiltshire, ibid., 1929, 62, [B], 3072; A., 1930,46 E. de B. Barnett and F. C. Harrison, ibid., 1931,64, [B], ‘535 ; A., 612.47 E. de B. Barnett and L. A. Low, ;bid., p. 49; A., 341.48 Compare E. de B. Barnett and C. L. Hewett, ibid., p. 1572; A., 1058.4D Ann.Roports, 1928, 25, 127.50 H. Burton, J., 1930, 248; A., 1930, 460.[B], 472 ; A., 1930, 465.202ORUANIC CHEMISTRY.-PART II. 115The increased activation of a three-carbon anionotropic systemby polynuclear aryl groups is illustrated by the conversion of a-and P-naphthylvinylcarbinols into y- 1- and y-2-naphthylallylp-nitrobenzoates, respectively, by the action of p-nitrobenzoylchloride and pyridine, under which conditions the correspondingphenyl derivatives each give the ester of the original alcohol.51The position of equilibrium of such systems, however, islargely affected by experimental conditions. Thus, whereas theaction of anhydrous hydrogen halides on either cinnamyl ora-phenylallyl alcohol gives only cinnamyl halides, treatment ofcinnamyl chloride with 70 yo aqueous-alcoholic potassium hydroxideaffords 20-25%, and with silver oxide in absolute alcohol, 35-45%,of a-phenylallyl ethyl ether.52CHPh:CH*CH,-Cl *- CHPh.CH CH, =+ p. @ne mCHPh*CH:CH, Ph*CHCl*CH:CH,The formation of the ether is readily explained by the greaterco-ordinating power of the ethoxide, relative to that of the chlorideion. In the halides recombination of the anion occurs exclusivelyin the y-position to the phenyl group, but the ethoxide ion combinesin the a-position, indicating a considerable displacement of theequilibriu‘m under these conditions in favour of the other electro-meric form of the kation.Differences in experimental conditions also explain C. Prhvost’s 53failure to confirm H.Burton’s results (above) on the interconversionof crotyl and mefhylvinylcarbinyl esters, since the low dielectricconstant of the solvents (toluene and trichloroacetic acid), the lowertemperatures, and the shorter periods of heating employed mayprevent a system of such small mobility from attaining completeequilibrium.Aromatic Substitution.(Continued from Ann. Reports, 1930,27, 130.)General Theory. Dynamics of Aromatic Substitution.-Themodern electronic view of aromatic substitution has been elab-orated almost exclusively from observations of the proportions of62 J. Meisenheimer and J. Link, Annalen, 1930, 479, 211; A., 1930, 769 :compare H. Gilmm and S. A. Harris, J . Amr. Chem. Soc, 1931, 53, 3541;A., 1290.E. Burton, J., 1931, 759; A., 723.53 Bull.SOC. chim., 1931, [iv], 49, 261; A., 601116 BAKER AND BENNETT:isomerides simultaneously formed, but four years ago the importancewas emphasized of considering not only the proportions of iso-merides, but also the relative velocities of substitution, and pre-liminary data of the latter kind were rep0rted.5~ Accurate measure-ments of the reduced velocity of substitution of toluene relativeto benzene have now been furnished by C. K. Ingold, A. Lapworth,E. Rothstein, and D. Ward,55 and the effect of certain modificationsin experimental conditions has been ascertained. Under standardconditions (nitration by acetyl nitrate at 30") the values of the partialrate factor F (previously designated as the coefficient of activation,oix., the factor by which the introduction of the directing groupincreases the probability of substitution at a given nuclear carbonatom) for the o-, rn-, and p-positions are respectively 40, 3.0, and51.Hence, in agreement with the earlier findings of C . K. Ingoldand F. R. Shaw,= the methyl group not only causes a large increasein op-reactivity but also a small increase in m-reactivity. Altera-tion of the reagent and solvent to nitric acid in nitromethane gaveidentical values for F , whilst changing the temperature to 0"resulted in a slightly higher reduced velocity and generally highercoefficients of activation.It was shown by A. E. Bradfield and B. Jones 56 that in o- andp-substituted alkoxybenzenes the two substituents contributecharacteristically and additively to the logarithm of the velocityof nuclear halogenation, on the assumption that in the equationfor the critical energy increment k = ae-E'RT, variations in k aredue entirely to variations in E, a remaining constant.The halo-genation of a further series of phenyl ethers and of p-tolyl ethersXof the general formula RO O M e at 20" and 35" has now beenstudied.57 There is little difference between the rates of chlorin-ation of corresponding chloro- and bromo-ethers, and the groupcontributions for the new phenyl ethers examined are in agree-ment with the earlier results. The data also serve to confirm theoriginal hypothesis above mentioned and to discredit three other(more complicated) possible assumptions.At the same time someof the figures reveal a definite tendency to departure from thesimple additive relation in directive effects of groups. Thus therelative effects in the series of tolyl ethers agree with the resultsfor phenyl ethers when X is NO, but not when X is a halogen;64 Ann. Reports, 1927, 24, 152.55 J., 1931, 1969; A., 1405.56 Ann. Reports, 1928, 25, 143.5 7 A. E. Bradfield and B. Jones, J . , 1931, 2903; A. E. Bradfield, W. 0.Jones, and F. Spencer, ibid., p. 2907ORUAHIU CHBMISTRY .-PART II. 117and in general the relative directive effects are 5-15% lower inthe tolyl ether series than for the corresponding phenyl ethers.The conclusion that the nitroso-group is m-directive 68 was basedmainly on the slow velocity of bromination and absence of p -substitution of nitrosobenzene in acetic acid, in which solvent it isnot associated, and on the reaction of the bromine in p- but not inm-bromonitrosobenzene with silver nitrate in acetic acid.Cautionshould be observed, however, in accepting this conclusion, sinceR. J. W. Le F h r e 59 has found that p-bromonitrosobenzene reactswith silver nitrate under conditions in which even picryl bromide(activation by three nitro-groups) is unattacked. Moreover,nitrosobenzene can be mono-p-brominated in benzene, a solventin which it is also unimolecular. The most satisfactory view ofthe properties of the nitroso-group would seem to be that it is capableof electromeric effects of either sign,60 aromatic hydrogen substi-tution or replacement of halogen being controlled by displacements,of type (I), whereas hydrolytic reactions (e.g., the hydrolysis ofp-nitrosodimethylaniline) are initiated by those of type (11).Ionogenic Systems.-By analogy, with Schiff ’s bases, which havepreviously been proved 61 to exist, in concentrated sulphuric acidsolution, as salts of the type PhCH:NHA.r}%, J.W. Baker 62 hassuggested that the intensely coloured solutions formed by benzalde-hyde and acetophenone in the same medium are due to the formationof oxonium salts of the type PhCR:OH}HSO,, the ions of whichare in equilibrium with the colourless, pseudo-salt form. Partition(between sulphuric acid and ligroin) and colorimetric data indicatethat the equilibria@ -0- 0f - - - __ - - -- - - - -- - colourless - - _- - - _- - - - _- - ____ - - ___ - - - 3 coloured87+ PhCR:O + HO*S03H + PhCR(OH)*O*SO,H T- O*803H + PhCR:OH +are displaced largely towards the right even in SOY0 sulphuric acid.As in the case of Schiff’s bases, the distribution of the positivecharge on the carbonium-oxonium kation causes a considerableincrease in the proportion of m-nitration observed under these5% Ann.Reports, 1930,27, 130.59 J., 1931, 810; A., 945 : but compere D. L. Hammick, ibid., p. 3105.6O R. Robimon, Chem. and I d . , 1925, 44, 456.61 Ann. Rep&, 1930,27, 136.soluble f -- ----- --- ---- insoluble in ligrob _________ - __________ __-62 J., 1931, 307; A. 486118 BAKER AND BENNETT :conditions.63 Thus in 7.3% oleum, benzaldehyde and acetophe-none afford 90.8 and 90.0% of the m-isomeride, respectively. Thisproportion decreases gradually as the concentration of the sul-phuric anhydride is diminished until in 8076 sulphuric acid thevalues are 83.9 and 83*1%, and in nitric acid (d 1.53) alone, 72.1and Toy0, respectively.Moreover, in all cases, addition of ammon-ium sulphate to the sulphuric acid nitrating medium causes 5t de-pression in the amount of m-isomeride formed, comparable bothin magnitude and in type with that observed in the case of Schiff’sbases, an indication that substitution occurs mainly through thekation of the oxonium salt.MisceZkcneous.-Further examples of the effect of experimentalconditions in altering the proportion of isomerides formed havebeen recorded.Thus, although the occurrence of a large amount(85%) of m-substitution when phenylboric acid is nitrated withnitric acid (d 1.53) has been confirmed, in acetic anhydride a 65%yield of a mixture containing 95% of o- and 5% of p-nitrophenyl-,boric acid is obtained.64 Pending further investigation, this resultsuggests that the explanation of the m-directive power previouslygiven65 should be accepted with reserve.That the nature of the substituting reagent also affects tlre posi-tion of substitution is illustrated by results obtained with diphenylderivatives and diphenyl ethers. Thus p-acetamidodiphenyl etheris nitrated 66 and brominated 67 respectively in the positions shown :these results forming a parallel with those obtained by J. Kenyonand P.H. Robinson in the case of 4-acetamidodiphenyl. Nitra-tion of 4-acetamido-4’-methoxydiphenyl ether also occurs in posi-tion 3, whilst p-methoxydiphenyl ether is brominated in the 4’-position. Similar differences are found by F. Bell 69 in the caseof 3-bromo-4-p-toluenesulponamidodiphenyl, which is nitrated inposition 5, but brominated in position 4’. The explanation of theseresults may lie in the lower degree but higher frequency of activa-tion in position 4’ than in position 3 or 5,’* so that the more ener-G3 J. W. Baker and W. G. Moffitt, J., 1931, 314; A., 485.64 W. Seaman and J. R. Johnson, J . Amer. Chem. SOC., 1931,53,711; A., 502.6 5 Ann. Reports, 1930, 27, 133.6 6 M. Oesterlin, Monutsh., 1931, 57, 31 ; A., 479.6 7 ,Ann.Reports, 1930, 27, 142.70 A. Lapworth and R. Robinson, Mem. Munchester Phil. SOC., 1927, 72,J . , 1926, 3050; A., 1927, 142. J . , 1931, 2338; A., 1284.43; A., 1927, 546ORGAN10 CHEMISTRY.-PART II. 119getically negative-centre seeking reagent, bromine, enters position4’. When bromination of 3- bromo-4-p- t oluenesulphonamidodi-phenyl is carried out in pyridine, the activating power of the p -toluenesulphonamido-group is increased by removal of its incip-iently ionised hydrogen by salt formation, and the second bromineenters at position 5.In conclusion, attention may be directed to investigations on theaction of bromine on phenols,71 and on the chlorination of iodo-phenols. 72Polycyclic A r m t i c Compounds.No systematic report on this subject has been made for severalyears, but limitation of space restricts the following summary to abrief outline of a few of the more important lines of general develop-ment. Attention may be directed to the monograph on ‘‘HigherCoal Tar Hydrocarbons ’’ by A.E. Everest which gives an accountof the chemistry of higher polycyclic aromatic hydrocarbons up tothe end of 1926.After removal of 1 : 6-, 2 : 6-,and 2 : 7-dimethylnaphthalenes from low-temperature coal tar,2 : 3-dimethylnaphthalene has been isolated as its 6-sulphonic acidand converted into various derivatives. 73The ct-directive catalytic infiuence of mercury in the sulphon-ation of naphthalene finds a parallel in the exclusive formation of@-derivatives when tetrahydronaphthalene is condensed with alkylbromides or acyl chlorides in the presence of aluminium halides,other metallic halides affording mixtures of a- and p-derivatives.74Catalytic dehydrogenation of the products affords S-alkylnaphth-alenes and p-naphthyl ketones, respectively. Similar condens-ation of tert.-butyl chloride with naphthalene itself, however, givesa mixture of di-tert. - butylnaphthalenes.75By modifications of the general method involving ring-closureof substituted y-phenylbutyryl chlorides with aluminium chloride,followed by reduction and subsequent catalytic dehydrogenation,I. M. Heilbron and his co-workers have synthesised l-methyl-5-,-6-, and -7-eth~lnaphthalene,’~ and 2 : 3 : 5-, 1 : 3 : 5, and 1 : 3 : 8-t~imethylnaphthalene.~~ . Neither the 1 : 3 : 5- nor the 1 : 3 : 8-derivative is identical with the trimethylnaphthalene obtained bydehydrogenation of tetracyclosqualene.78 Since the oxidation productsNaphthalene.-Alkylnaphthalenes,71 G. Heller (with others), J. pr. chem., 1931, [ii], 129, 211; A., 477.72 S. Buchan and H. McCombie, J., 1931, 137; A., 346.73 0. Kruber, Ber., 1929, 82, [B], 3044; A., 1930, 202.74 A. Barbot, Bull. SOC. chim., 1930, [iv], 47, 1314; A., 208.75 W. Gump, J . Amer. Chem. SOC., 1931, 53, 380; A., 341.76 J. Harvey, I. M. Heilbron, and D. G. Wilkimon,J., 1930,423 ; A., 1930,693.7 7 D. G. Wilkinson, J., 1931,1333; A., 948. 78 Ann. Reports, 1927,24,128120 BAKER AND BENNETT:of the latter could arise only from the 1 : 3 : 8- or the 1 : 2 : 5-tri-methyl derivative, it must be the latter,79 a conclusion subsequentlyconfirmed by the synthesis of this hydrocarbon by L.Ruzickaand J. R. Hosking.80 The same hydrocarbon results from thecatalytic dehydrogenation of Congo copal oil.81 The syntheses of1 : 5-, 1 : 8-,82 and 2 : 8-83dimethylnaphthalene have also beeneffected. The conversion of 2-methylnaphthalenes into benz-anthracenes is discussed on p. 126.Substitution of naphthalene derivatives. The problem of orient-ation in the naphthalene nucleus is complex from both the experi-mental and the theoretical point of view. The study of this fieldon modern lines has not yet made much progress, but a few recentinvestigations may be mentioned.The nitration of cc-chloro- or a-bromo-naphthalene occurs SUC-cessively at positions 4, 5 , and 8, and of a-alkoxynaphthalenes a tpositions 2, 4, and 5.85 Nitration of 2-chloro-, bromo-, or alkoxy-naphthalene yields the 1 : 6 : 8-trinitro-derivati~e.~~ The halogenatom in such compounds is readily replaced by positive-centreseeking groups such as OH, OR, and S.The influence of a nitro-group in producing high reactivity in a halogen atom is found byJ. Salkind 87 not to extend from one ring to the other of the naphth-alene nucleus. On the other hand it is well known that inhalogen substitution a group often deactivates one nucleus asa whole relative to the other.84Chlorosulphonic acid converts l-methylnaphthalene into the4-sulphonic acid,88 although 2-methylnaphthalene is stated to givethe 8-sulphonic acid.89 Further nitration of a mixture of 4- and5-nitro-l-methylnaphthalene gives the 4 : 5-dinitro-derivative,whilst the presence of some 2 : 4-dinitro-compound is indicatedby the formation of 2-nitro-4-amino- and 4-nitro-2-amino-l-methyl-naphthalene on reducti~n.~OI. M.Heilbron and D. G. Wilkinson, J., 1930, 2546; A., 80.8o Helv. Chim. Acta, 1930, 13, 1402; A., 231.81 L. Wertenburg and J. P. Wibaut, Rec. trav. chim., 1931, 50, 188; A . , 484.82 V. Veselg and F. &ursa, Coll. Czech. Chm. Comm., 1931, 3, 430; A.,83 V. Vesely and A. Medvedeva, ibid., p. 440 ; A., 1282.84 Ann. Reports, 1926, 23, 134; 1930,27, 140.85 H. W. Talen, Rec. trav. chim., 1928, 47, 329, 346; A , , 1928, 405.86 E. J. van der Kam, ibid., 1926, 45, 564, 722 ; A., 1926, 1029, 1239.87 Ber., 1931, 64, [B], 289; A., 474; compare Ann.Reports, 1929, 26, 132.R. E. Steiger, Helv. Chim. Acta, 1930, 13, 173; A., 1930, 593.K. Dziewoliski and A. Wulffsohn, Bull. Acad. Polonaise, 1929, A , 143;*O V. Vesely, F. &ursa, H. OlejnSek, and E. Rein, Coll. Czech. Chm. Comm.,1282.A., 1929, 803.1929, 1, 493; 1930,2, 145; A., 1929, 1288; 1930, 593ORQANIU CHEMISTRY.-PBRT II. 121An investigation of the bromination of p-naphthol by K. Friesand K. Schimmelschmidt 91 has explained various discrepanciesin the literature. Such bromination affords, successively, thel-mono-, 1 : 6&-, and 1 : 4 : 6-tri-bromo-deri~atives.~~ The tetra-bromo- p-naphthols, formed by bromination in acetic acid, consistof the 1 : 3 : 4 : 6-, 1 : 3 : 5 : 6-, and 1 : 3 : 6 : 8-derivativesY thelast two compounds not being formed by simple substitutionprocesses.The reaction C,,H,*OH(p) + Br, CIoH,Br*OH +HBr is reversible, since treatment of l-bromo-p-naphthol with asaturated solution of hydrogen bromide in acetic acid in the presenceof potassium iodide (to remove bromine) affords p-naphthol. Thecourse of bromination is largely influenced by the conversion ofp-naphthol into quinonoid forms. Bromination of keto-bromides(the formation of which is favoured by the addition of sodiumacetate to remove hydrogen bromide) and subsequent reductionof the products gives rise to different derivatives from thoseobtained when bromo-p-naphthols are brominated. Thus 1 : 3 : 6-and not 1 : 4 : 6-tribromo-p-naphthol is produced when 1 : 1-dibromo-2-keto-1 : 2-dihydronaphthalene is brominated and theproduct reduced.The mechanism of the formation of the 1 : 6-dibromo-compound and its successive reconversion into the6-bromo-derivative and into p-naphthol is indicated in the followingscheme :Br Br Br,-HBr 1slow2 7HBrSimilar ketonisation of 2 : 4-dibromo- a-naphthol is suggested as9 1 Annulen, 1930, 484, 245; A., 216.92 Compare H. Franzen and G. Stauble, J . p r . Chern., 1921, [ii], 103, 362;A., 1922, i, 450122 BAKER AND BENNETT :the mechanism of its conversion into the indigotin type of deriv-ative (I) under the influence of alkali : 93OH 0 0Bromination of 1 : 5-dihydroxynaphthalene yields the 2 : Ci-dibromo-derivative, which, on oxidation, affords 2 : 6-dibromo-5-hydroxy-1 : 4-naphthaquinonq only one of the rings being converted intothe quinonoid f0rm.~4An interesting new re-action of various aryl diazosulphonates of p-napht hol- 1 -sulphonicacid has been investigated by F.M. Rowe and his ~ollaborators.~5Whilst acidification of a solution of 4’-nitrobenzene-2-naphthol-l-diazosulphonate (11) in a molecular quantity of sodium hydroxidegives a quantitative yield of Para-red (p-nitrobenzeneazo-fi-naphth-ol), addition of the diazosulphonate in sodium carbonate solutionto an excess of sodium hydroxide and subsequent acidificationgives only a trace of Para-red, the main product being the sodiumsalt of 3 - (4’- nit rop hen y 1) - 1 : 3 - di h y dr op ht halazine - 4 -acetic - 1 - sul-phonic acid.This compound, to which structure (V) is provisionallyassigned, is converted by boiling hydrochloric acid into the corre-sponding 1 -hydroxy-derivative (VI).Although the condensation products of diazotised p-nitroanilinewith 1 -halogeno- or 1 -methyl- p-naphthol are true diazo-oxide~,~~the initial stage in the above reaction is the formation, not of adiazo-oxide (XII) as postulated by H. T. Bu~herer,~’ but of sodium4’-nitrobenzene-l-azo-fi-naphthaquinone-l-sulphonate (111), ringfission and subsequent cyclisation of the acid (IV) giving thedihydrophthalazine derivative (V). The corresponding hydroxy-compound (VI) is reduced to l-hydroxy-3-(4’-aminophenyl)tetra-hydrophthalazine-4-acetic acid (VII).The possible alternativeisoquinoline structure (XIII) is shown to be untenable by a com-parison of its properties with those of ~V-4’-nitrophenylaminoiso-93 R. Willstiitter and L. Schuler, Ber., 1928, 61, [B], 362; compare S.94 A. S.WheelerandD. R. Ergle, J. Amer. Chem. SOC., 1930,52,4872; A., 217.98 F. M. Rowe, E. Levin, A. C. Buri~s, J. S. H. Davies, and W. Tepper,J., 1926, 690; A., 1926, 625.g6 F. M. Rowe and A. T. Peters, J., 1931, 1065; A., 835; compare J.Pollak and E. Gebauer-Fiilnegg, Monutsh., 1928, 50, 310; A., 1929, 58.9 7 Ber., 1909,42,47; A., 1909, i, 193; H. T. Bucherer and C. Tama, J. pr.Chem.. 1930,127,39; A., 1930, 1280; compare A. Wahl and R. Lantz, Bull.SOC. chirn., 1923, 33, 97; A . , 1923, i, 209.Naphthalene-azo- and diazo-compounds.Goldschmidt and H.Wessbecher, ibid., p. 372 ; A., 1928, 408, 409ORGANIC CHEMISTRY .-PART 11. 123carbostyril-3-carboxylic acid (XIV), a rational synthesis of whichmas effected.SO,*N:NR NaO,S\/N:NR CH*N:NR ~CH:CH*CO,Na J7 S03NaI _ _ , i(11.1 (111.) (IV.1CH*SO,Na CH-OH CH*OHHC1 -+Qg - + / ‘($C-CH,*CO,H CH*CH,*CO,H // C*CH,.CO,Na , I’CHI 4(XII.)(VIII.) (IX.)Zn + HCl I oxidation 1 Me,SO,C=OMe phthdic acid +benzoquinone $pRf1XJS}8H p HMeC*OMe co(R = p-NO,*C,H,* ; R’ = p-NH,*C6H,*)Boiling with dilute mineral acids converts (VI), with eliminationof acetic acid, into 4’-nitro-3-phenylphthalaz- 1-one 98 (VIII).98 F. M. Rowe and E. Levin, J., 1928, 2658; A,, 1928, 1262124 BAKER AND BENNETT :The latter, in agreement with the betaine structure assigned,exhibits both acidic and basic properties and is reduced to thecorresponding amino-compound (IX), similarly obtained from(VII). The isomeric 4’-nitro-3-phenylphthalaz-4-onej which wassynthesised for comparison, is insoluble in alkali and does not yieldsalts with mineral acids. On the other hand, cold acid potassiumdichromate merely decarboxylates the acetic acid side chain in(VI), giving 4’-nitro-3-phenyl-4-methylphthalaz- 1 -one (XI).99A similar series of derivatives is obtained from 3’-nitrobenzene-land 2’ : 6‘-dichloro- and 2’ : 6’-dibromo-4’-nitrobenzene-2-naphthol-l-diazosulphonates,2 but it is perhaps significant that in this seriesof decreasing - I and increasing + T effects there is an increasingtendency towards the formation of the corresponding benzeneazo-p-naphthols.This, together with the fact that, with the diazo-sulphonates derived from such components as aniline, toluidine,2 : 5-dichloroanilineY and anthranilic acid, no formation of phthal-azine derivatives was observed, the presence of a nitro-group being,in fact, essential, suggests that the latter reaction is favoured by apowerful - I effect, whilst conversion into the benzeneazo-p-naphthol is facilitated by a + T effect. The observation that thenew reaction does not occur with the derivative from diazotisedsulphanilic acid may possibly be explained by the presence of the-++/- 0b anion S-0 in the alkaline medium, but the close polar similarityof the NO, and S0,R groups suggests that an examination of thederivatives from diazotised sulphanilic esters or p-aminophenyl-sulphones would be of interest.The scheme given on p.123 summarises the main results (includingthose obtained on methylation of the phthalaz-l-ones, which cannotbe dealt with in detail in this Report), the constitutions being thoseprovisionally assigned by the authors. The structure (VI), however,is open to the criticism that a nitrogen atom with two unsharedelectron pairs could scarcely be stable in juxtaposition to an am-monium nitrogen atom. A more probable constitution for thissubstance is the dihydrophthalaz-l-one structure (XV). 3 : 4-Elimination of acetic acid from its betaine form (XVI) would thenreadily explain its conversion into the phthalaz-l-one (VIII).The formation from the diazosulphonate would be represented bythe following scheme, which also suggests a reason for the facilit-ating effect of - I groups in the substituent R (see above).09 F.M. Rowe, E. Levin, and A. T. Peters, J., 1931, 1067; A., 835.1 F. M. Rowe, M. A. Himmat, and E. Levin, J., 1928,2556 ; A., 1928,1262.2 F. M. Rowe, C. Dunbar, and N. H. Williams, J., 1931, 1073; A . , 835ORGANIC CHEMISTRY.-PART TI. 12570,Naacids --+H*CH2*C02NaC*OH co--+CH*CH,*CO,H CH*CH,* C0,H- AcOH - 3 (VIII.) (XVI.)CH ;\H\ '\CH,*CO,HThis view of the structure (XV) receives support from thefact that preliminary experiments have recently indicated thatN-methyl derivatives of substances of this type can be prepared.,Anthracene.-Certain evidence has been adduced in favour ofthe Armstrong rather than the Graebe-Liebermann structure foranthracene.Thus reduction of active benzyloxanthrone-2-carb-oxylic acids affords inactive 9-benzylanthracene-2-carboxylic acid,4whilst the presence of two double linkings at the 9- and 10-positionsagrees well with the observation that anthra- /\/I\,\ cene reacts additively with ap-unsaturatedacids and esters to form stable derivatives 1 11 :IaoIl I of the type anthracene-9 : 10-endomaleic \/\I/\/ anhydride (I). Such arguments are based,however, on a static conception, and itseems unlikely that the 9 : 10-bridged an-thracene form would be any more permanent than is the Dewarphase in benzene.g(1.)J Private communication from Professor F.M. Rowe.4 H. Goudet, Helu. Chim. Acta, 1931,14, 379; A., 619.6 Compare E. Clar, Ber., 1931, 64, [B], 1676, 2193; A., 1044, 1292.0. Diels and K. Alder, Annalen, 1931, 486,191 ; A., 848126 BAKER AND BENNETT :Alkylanthracenes. The presence of 2 : 6- and 2 : 7-dimethyl-,*2 : 3 : 6-trimethyl-, and 2 : 3 : 6 : 7-tetramethyl-anthracene in low-temperature tar has been codrmed by direct synthesis of thesehydrocarbons.’ The appropriate methyl-substituted benzophenone(prepared by condensation of the Grignard compound of a halogeno-methylbenzene with p-toluonitrile) is slowly converted into theanthracene on heating :Me MeM e o r + C N O M e M e ) C O O M e ---+Aromatic hydrocarbons may be conveniently alkylated by treat -ment with the appropriate alcohol and 80% sulphuric acid a t70-80”.* Thus, with benzyl alcohol, toluene and o-xylene afford,in addition to phenyl-p-tolylmcthane and 4-benzyl-o-xylene,anthracene and 1 -methylanthracene, respectively, the latter result-ing from oxidation of the intermediate 9 : 10-dihydro-derivatives.Owing to their carcinogenetic properties the synthesis of benz-and dibenz-anthracenes has recently assumed considerable import-ance.Distillation of l-benzyl-2-methylnaphthalene with zinc dustaffords mainly 1 : 2-benzanthracene together with a little of the2 : 3-compound, whilst the corresponding .ketone gives the 1 : 2-derivative exclusively.9 By the condensation of 2-methylnaphth-alene with p-naphthoyl chloride, E.Clar lo obtained Z-methyl-1 : 2’-dinaphthyl ketone, pyrogenic decomposition of which gives1 : 2 : 5 : 6-dibenzanthracene. I n the similar decomposition of2-methyl-1 : 1’-dinaphthyl ketone J. W. Cook l1 has shown thatisomerisation to the 1 : 2’-ketone probably precedes cyclisation,since 1 : 2 : 5 : 6-dibenzanthracene is again formed and not the1 : 2 : 7 : 8-compound (as stated by Clar). The same compound isobtained by pyrolysis of 1 : 4’-dimethyl-1 : 1’-dinaphthyl ketonewith elimination of the methyl group in the a-position to a con-densed ring.* Described by J. Lavaux and &.I. Lombard (BulE. SOC. chirn., 1910, [iv], 7,539; A., 1910, i, 548) as the 2 : 7-, and 1 : 6- or 1 : 7-derivatives, respectively.G. T. Morgan and E. A. Coulson, J . , 1929, 2203, 2551; 1931, 2323; A .,1929, 1436; 1930, 80; 1931, 1282.H. Meyer and K. Bernhauer, Monatsh., 1929, 53 and 54, 721 ; A., 1929,1441.K. Dziewoliski and E. Ritt, Bull. Acad. Polowise, 1927, 3, [ A ] , 181 ; A.,1928, 52.lo Ber., 1929, 62, [B], 350; A., 1929, 435.l1 J . , 1931, 487, 489; A., 612ORUANIC CHEMISTRY.-PART II. 127By the action of Grignard reagents on 1 : 2 : 5 : 6-dibenzanthra-quinone and dehydration of the resulting diols a series of 9 : 10-dialkyl-1 : 2 : 5 : 6-dibenzanthracenes has been prepared : l2 thespectrum of the dibenzyl derivative is almost identical with thatof the carcinogenetic mixture obtained by the action of aluminiumchloride on tetralin.13 Similar spectra are shown by phenanthra-naphthene and phenanthrafluorene. Pyrogenic decomposition of1 : 5-dibenzoyl-2 : 6-dimethylnaphthalene affords 2’ : 1’-anthraceno-1 : 2-anthracene l 4 (11), 1 : 2 : 3 : 4 : 5 : 6-tribenzanthracene(111) is obtained by similar methods.15andAnthraquinone derivatives.According to A. Meyer l6 conversionof anthraquinone-a-sulphonic acid into the p-acid by heating withsulphuric acid occurs only in the presence of metallic mercury.Since the p-acid is stable under the same conditions, the almostexclusive a-substitution observed l7 when anthraquinone is sul-phonated in the presence of mercury salts cannot be due to theprimary formation of the p-acid and subsequent isomerisation.Disulphonation of anthraquinone in the presence of mercury saltsgives 1 : 5-(4O-&y0), 1 : 8-(23y0), and traces of the 1 : 6- and 1 : 7-disulphonic acids.The a-directive catalytic influence of mercuricsalts is also emphasised in a systematic re-investigation of thesulphonation of or-chloro- and dichloro-anthraquinones by A. A.Goldberg,ls in the course of which 1 : 2 : 3-, 1 : 2 : 5-, 1 : 2 : 6-,1 : 2 : 7-, 1 : 3 : 6-, 1 : 3 : 7-, 1 : 4 : 5-, and 1 : 4 : G-trichloroanthra-quinones are synthesised and oriented.An interesting series of A2-tetrahydroanthraquinones hydro-genated in the “ twin ” positions (designated as y in naphthaleneand 6 in anthracene), obtained by addition of hydrocarbons withl2 J. W. Cook, loc. cit.lS I. Hieger, Biochem. J., 1930, 24, 505; A., 1930, 807.l4 E. Clar, F. John, and B. Hawran, Ber., 1929,62, [B], 940, 950; A., 1929,l5 L.F. Fieser and E. M. Dietz, ibid., p. 1827; A . , 1929, 1055.l6 Compt. rend., 1926, 183, 519; Bull. SOC. chim., 1927, [iv], 41, 1627; A.,1926, 1146; 1928, 781.1’ H. E. Fierz-David, Helv. Chim. Acta, 1927, 10, 197; 1928, 11, 197; A.,1927, 463 ; 1928, 293.1s J., 1931, 1771 ; A . , 1062.689128 BAKER AND BENNETT:conjugated double linkings to benzo- and naphtha-quinones wasmentioned in Part I of last year’s Report.19Bolecular Compounds.Under this heading some reference will also be made to therelated subjects of association and chelation. If these phenomenaare approached from the merely physical point of view, theirexplanation may be attempted exclusively in terms of dipoleassociation and intermolecular forces due to the residual valencyfields of the molecules or van der Waals forces.Many chemists,however, although admitting the importance of the considerationsmentioned, prefer to regard the formation of new chemical mole-cules as a, principal factor. Thus, N. V. Sidgwick20 in particularhas represented association as involving the formation of newmolecules by means of co-ordinate linkages, and the extension ofthis view to molecular compounds in general would seem reason-able.21 Molecular compound formation and association will thenbe regarded as similar intermolecular co-ordination phenomenabetween different and like molecules respectively, whilst chelationmay be regarded as the analogous intramolecular process. It maybe pointed out that this view follows the trend of modern chemicaltheory, which has been increasingly to attempt the representationby definite structural formula? of complexes a t first regarded asindefinite assemblages, the most important instance of this beingWerner’s theory, and another recent one the polymerisation theoryof H.Staudinger.22The isolation of a crystalline specimen is definite evidence of achemical fact, but it is necessary to bear in mind that forces of thesecond order may contribute largely to the stability of a crystalassemblage. A true molecular compound will survive, to someextent at least, in the liquid or dissolved condition, and proof ofthis survival in the liquid state is very desirable. To take a recentexample, compounds have been isolated in which either deoxycholicacid or apocholic acid (dihydroxy-carboxylic acids, saturated andcontaining one double bond, respectively) is associated with 8 mols.of either stearic or palmitic acid or of cetyl It is difficultto believe that these are united by chemical bonds.The recent appearance of a new edition of the important mono-lb Ann.Reports, 1930, 27, 89.2o “ The Electronic Theory of Valency,” 1927, p. 132.21 T. M. Lowry, Chem. and Id., 1924, 43, 218 ; G. M. Bennett and G. H.Willis, J., 1929, 256 ; A., 1929, 436.22 Ann. Reports, 1929, 26, 105-115.23 H. Rheinboldt, 2. physiol. Chem., 1929,180, 180; A., 1929, 443ORQANIC CHEMISTRY.-PART 11. 129graph on molecular compounds by P. Pfeiffer 24 makes availablean admirably classified survey of this field.Chelate Compounds.-The chelate ring in o-substituted aromaticcompounds, first suggested by P.Pfeiffer 25 for l-hydroxyanthra-quinone, was closely studied by N. V. Sidgwick and his colleagues.26An examination has now been made 27 of the parachors of certainaromatic compounds having the chelate ring. Four substances ofthe type o-C,H,(OH)X (where X is NO,, CHO, or C02Me), such as(I), consistently show a defect in their parachor values of 14.4below that calculated (due allowance being made for the presenceof a six-membered ring), whereas the corresponding methyl ethersgive normal values. Of this defect, 1.6 is regarded by the authorsas due to the transferred electron and 12.8 as associated with therise in the covalency of hydrogen from 1 to 2.In passing from ter-to quinque-valent phosphorus in the chlorides there is a similarcontraction of 25 units. These figures can equally well be numeric-ally explained by means of formulae involving singlet linkages.28S. Sugden regards the hydrogen atom with four shared electronsas inconsistent with Pauli’s principle. N. V. Sidgwick29 contendsthat this is not so, a second quantum group being permissible,but that the odd electron of the singlet linkage would on the otherhand be definitely anomalous.Marked differences of boiling point and solubility have beenascribed to self-co-ordination in the o-nitrobenzyldialkylamines (II),30but the melting points of o-nitrodialkylanilines31 should not betaken as evidence of chelation, and the four-membered ring whichwould be formed is improbable on stereochemical grounds.Itseems unjustifiable, moreover, to postulate chelate rings involvinghydrogen attached to carbon.3224 “ Organische Molekulverbindungen,” 2nd Ed., 1927.25 Annalen, 1913,398,137; A., 1913, i, 879.26 Ann. Repwts, 1924, 21, 104.27 N. V. Sidgwick and N. S. Bayliss, J., 1930, 2027; A., 1240.28 S . Sugden, “ The Parachor and Valency,” 1930, p. 150; and J., 1927,29 LOC. cit. and J., 1924, 125, 532; A., 1924, i, 506.30 G. M. Bennett and G. H. Willis, Zoc. cit.31 H. H. Hodgson and A. Kershaw, J., 1930, 497; A., 1930, 595.32 W. Kistiakowski, 2. physikal. Chem., 1928, 137, 383; E. de B. Barnettand J. A. Low, Ber., 1931, 64, [B], 49; T. M. Lowry and W.V. Lloyd, J.,1929, 1784; A., 1929, 22, 1186; 1931, 341.1173; A., 1927, 714.REP.-VOL. XXVIII. 130 BAKER AND BENNETT:A number of chelate metallic compounds are referred to in thefollowing section.The subject of association cannot be discussed here in detail,but reference may be made to reviews of the evidence from observ-ations of molecular polarisation by J. Errara 33 and C. P. Smyth.34Metal Co-ordination Cmpounds.-The lithium halides form withaliphatic amines a series of compounds decomposing a t or belowlaboratory temperature and containing 1 - 4 and sometimes 5molecules of amine per atom ofCompounds of the type MB,HB [where HB is +indoxyl-spiro-cyclopentane and M is lithium, sodium or potassium], soluble intoluene, are formed even in presence of a large excess of the alkali.36They are satisfactorily represented as co-ordination compounds,c/c=o,\C-”Ithe metal being 4-covalent and combined,MgoE‘c\c as in the annexed formula.Alkali-metalderivatives of diketonic substances andpounds with a second molecule of the parent substance; and alkalio-nitrophenoxides combine with one molecule of ~alicylaldehyde.~’All these products are bichelate compounds with 4-covalent metalNH-c// I of salicylaldehyde tend to form com-atoms.A number of addition compounds of calcium, strontium, andbarium halides with one, two, or three molecules of mono- anddi-methylaminoacetic acid and betaine have been des~ribed,3~ suchas CaBr,,X,; BaI,,X,,4H20; SrC12,X,4H,0, where X is a mole-cule of the N-methylated glycine.Following Pfeiffer,39 the authorsformulate them with the carboxyl group co-ordinated to the metal,the alkylamino-groups being left free (I). The survival of a freeamino-group is, however, improbable: the formula (11) is to bepreferred, as it overcomes t,his difficulty and a t the same time showsthe analogy of the betaine complexes with the others.{ [Me,N*CH,*C( OH) :O],Ba( H20),)12 [( Me,lfH-CH,*C~),Ba( H20) ,]IT,(1.1 (11.133 “ The Dipole Moment and Chemical Structure,” P. Debye, 1931, p. 101.3 4 “Dielectric Constant and Molecular Structure,” 1931, p. 169; C. P.Smyth and others, J. Amer. Chern. Soc., 1929,51, 1736, 3312; 1930, 52, 1824;A., 1929, 994; 1930, 135, 841. See also N. V. Sidgwick, Zoc. c i t . and 2.EZeEtrochem., 1928, 34, 445; C.T. Zahn, Physical Rev., 1931, [ii], 37, 1516;A , , 1928, 13; 1931, 895.35 A. Simon and R. Glauner, 2, unorg. Chem., 1929,178,177; A . , 1929, 431.36 N. V. Sidpick and S. G. P. Plant, J . , 1925, 127, 209; A., 1925, i, 298.37 N. V. Sidgwick and F. M. Brewer, ibid., p. 2379; F. M. Brewer, J., 1931,38 W. K. Anslow and H. King, Biochem. J . , 1928,22, 1253; A., 1928, 1362.39 Op. cit., p. 140.361 ; A . , 1926, 71 ; 1931, 443ORGANIU CHEMISTRY.-PART II. 131A series of compounds of calcium chloride with four and of calciumiodide with six molecules of various amides such as urea, thiourea,urethane, phenylurea, and antipyrine have been prepared.40o-Phenylenediamine and o-tolylenediamine form a number ofcomplexes with cadmium and zinc chlorides and bromides contain-ing either two, three, or four molecules of amine per atom of themetal,41 such as Br2, and there are indicationsof the occurrence of isomerism.The octammine type is unusual andtherefore of particular interest : a cubic configuration is suggested.One or two complexes with m- and p-phenylenediamines are described,but evidence as to their molecular complexity would be desirable.A study of the conductivities in acetone and of the parachors ofsome sulphonium and ammonium mercuri-iodides leads to the con-clusion that they should be formulated as [R,N]+[HgI,]- andI *I [R,S]+[HgI,]- and that the negative ion may be I-Hg<I or I-HgeIThe compound of mercuric iodide and dibenzyl sulphide is a non-electrolyte and may be written R2S-Hg<I or alternatively withsinglet linkages.42Remarkably stable chelate compounds of dimethylthallium withP-diketones and salicylaldehyde have been prepared, a typicalstructure being Me T1’ b H .4 3 Parachor determinations onthese and other derivatives of P-diketones ‘with beryllium andaluminium are held by S. Sugden to point to the formula of thetype No It is here againequally possible to reconcile them with the alternative formula.The free diketones may contain some chelate form and some open-chain diketone.The hydrocarbons stilbene, dimethylbutadiene, and caroteneyield definite compounds with antimony and ferric chlorides ofthe composition X,2MC13.4540 F. R. Greenbaum, J . Amer. Phrrn. ASSOC., 1929,18, 784; A., 1929, 1169.41 W.WaM, F6rh. 111 nord. KernistmBtet, 1928, 172; A., 1929, 167.d2 H. J. Cave11 and S. Sugden, J., 1930, 2672; A., 26.43 R. C. Menzies, N. V. Sidgwick, E. F. Cutcliffe, and J. M. C. Fox, J., 1928,44 J., 1929,316; A., 1929,427; compare N. V. Sidgwick and L. E. Sutton,45 H. von Euler and H. Willstaedt, Arkiv Kerni, Min. Geol., 1929,10, B, 9 ;Zn NH2 C H [ ( N H h 4 ) JIO-CR‘O=CR/OTCRb H with singlet linkages.44-1288 ; A., 1928, 746.J . , 1930, 1472; A., 1930, 1062.A., 1930, 333132 BAKER AND BENNETT :A stable pink complex of nickel chloride with three molecules ofad-dipyridyl has been resolved into optically active forms throughthe tartrate. The salt [Ni,3dipy]C12,6H20 had [a]5461 + 550", theactivity vanishing rapidly in aqueous solution.46Nickel cyanide combines with aliphatic and aromatic amines,the complexes containing one or two molecules of the base.*' Thelack of further co-ordinating power in the compoundis held to show that the nickel is 4-covalentY the phenyl nucleusproviding one point of attachment.The molybdenum derivatives of several P-diketones prove tohave the composition MoO,[R*CO*CH*CO*R], and are typical co-ordination compounds.48The discovery of bivalent silver salts 49 has been followed by thepreparation of several complexes of the type [AgB,]X2, where Bis a-phenanthroline 50 or ad-dipyridyl.51I n forming co-ordination compounds with copper salts, themolecule of thiourea (tu) tends to form a, bridge between meta,latoms so that, besides the simple compound [Cu,2tu]N03,H20,there result others such as [Cu2,5tu](N03),,2H,0 ; [C~,,7tul(NO~)~ ;[Cu5,11tu](N03)5,8H20.The cyclic ethylenethiourea ( = etu) doesnot cause this complexity, and a series of compounds results suchas [ Cuy4etu]X, [Ag,4etu]X, [ Cd ,4e tu]X2 , [ Hg , 3etu]X2 , [ Pd ,4etu]X2together with one or two complexes with lower co-ordinationnumbers such as [Ag,3et~]C1.~1"The co-ordination -of chloroplatinic and chloroplatinous acidswith spy-triaminopropane, CH2(NH2)*CH(NH2)*CH,-NH2, yieldsthe interesting compounds[Ni( CN),,CH,Ph*CH,-NH,]which were each resolved into their optically active components byF. G. Mann.52 The central carbon atoms (*) are asymmetric. Acomplex with the same base of the formula [PtB2]12 was also pre-pared in which all the amino-groups are definitely engaged, makingthe metal 6-covalent.A number of other co-ordination compounds46 G. T. Morgan and F. H. Burstall, J., 1931, 2213; A., 1168.4 7 E. Hertel, 2. anorg. Chern., 1929, 178, 202; A., 1929, 380.4 8 G. T. Morgan and R. A. S. Castell, J., 1928, 3252.49 Ann. Reports, 1928, 25, 44.50 W. Hieber and F. Miihlbauer, Ber., 1928, 61, 2149; A., 1381.51 G. T. Morgan and F. H. Burstall, J., 1930, 2694; A., 234.51u Idem, J., 1928, 143; A., 1928, 278.52 J., 1927, 1224, 2904; 1928, 890, 1261; 1929, 409, 651; A., 1927, 754;1928, 157, 622, 745; 1929, 545, 678. Compare Ann. Reports, 1826, 23, 109OWANIC CIfEM3STRY.-PART II. 133of nickel, cobalt, and platinum with various aliphatic diamines suchas mono- and tri-aminotriethylamine, p-methyl-, p-hydroxy-, andp-bromo-trimethylamine have been described by the same author.The volatile acetylacetonate of trimethylplatinum 53 and asimilar derivative of diethylgold are evidently chelate compounds.The latter was isolated in the course of experiments with diethyl-gold bromide in which a number of other compounds of 4-covalentgoldwere describedsuchas the amines [Et2AuBr,NH3], [Et&uBr,Py],[Et2Au en]Br, and [Pra&u en]Br.From gold bromide there werealso prepared deep-coloured complexes [AuBr,,B] (where B ispyridine, quinoline, isoquinoline, 2-aminopyridine, or di-2-pyridyl-amine) and the compounds [AuBr,,Py,]Br and [Au en2]Br,.Compounds with Co-ordinated Oxygen.--Aliphatic alcohols yieldcrystalline hexacyanocobaltiates of the types [ROH,],[Co(CN),]and [ROH,],H[Co( CN),] which are evidently normal alkoxoniumderivatives.55 More complicated compounds are formed fromalcohols, ethers, and acetone with hydrogen chloride or bromideat low temperatures,s6 such as Et20,2HX and Et20,5HC1.Tri-phenylcarbinol yields with sulphuric acid the compoundCPh ,*OH,4H2S 0,. 57The coloration shown by cholesterol in chloroform with sulphuricacid is due to a red equimolecular compound, cholesterol sulphate.58The shape of the solubility curves of a number of aliphatic andcyclic ethers,59 of the isomeric butyl alcohols,60 and of cyclohexanolin water 61 indicates that there is some combination between thesesubstances and the water.There are several factors involved, butthe figures for the isomeric methyl butyl ethers show the expectedincrease of solubility arising from the increased co-ordinatingpower of an oxygen atom under the influence of the polar effectsof the adjacent methyl groups. That dibenzyl ether causes thepartial dissociation of benzoic and acetic acids dissolved in it mayalso be attributed to co-ordination of the acids with the ether.6263636s R. C. Menzies, J . , 1928, 565; A , , 1928, 609.54 C. S. Gibson and J. L. Sirnoneen, J., 1930,2531 ; C. S. Gibson and W. M.Colles, J., 1931, 2407 ; A., 78, 1316.5 5 F. Holzl, T. Meier-Mohar, and F. Viditz, Monutsh., 1929, 52, 73; A.,1929, 898.56 D.McIntosh,Proc.NovaScotiun Inst. Sci., 1928,17,112,116; A., 1929,292.5 7 H.R. Dittmar, J . Physical Chem., 1929,33, 633; A., 1929, 656.58 V. J. Nikolaev and S. A. Krastelevskaja, J . Rum. Phys. Chem. SOC., 1928,59 G. M. Bennett and W. G. Philip, J., 1928, 1930; A., 1928, 944.60 D. C. Jones, J . , 1929, 799; A., 1929, 638.61 N. V. Sidgwick and L. E. Sutton, J., 1930, 1323; A., 1930, 988.62 G. M. Bennett and G. H. Willis, J., 1928,2306; A., 1928, 1089.60, 1211 ; A., 1929, 61134 BAKER AND BENNETT :A qualitative test for weak bases, depending upon the formationof ferrichlorides in solution, is given by most oxygen, nitrogen, andsulphur c0mpounds.6~A crystalline sulphate of nitrobenzene, [Ph*NO,H]HSO,, has beendescribed, which is an ele~trolyte.~~ The increase in the conduc-tivity of sulphuric acid caused by addition of p-nitrotoluene is greaterthan with nitrobenzene, whilst dinitrobenzene has no such effect.Nitrobenzene forms an equimolecular compound with stannicchloride and the existence of the compounds 2PhN02,SnCI,(Br,)is deduced from the viscosity curves of mixtures of these suh-stances. 65A study of the freezing points of mixtures of carbon tetra-chloride and chloroform with acetone and ether66 shows theexistence at low temperatures of a number of compounds such asCCl,,Et,O ; CC14,2Et,0 ; CCl,,COMe, ; CHCl,,3Et20 ; CHCI3,2Et2O ;CHCl,,Et,O ; and 2CHC13,Et20.Cmpounds of Polynitro-aromatic Substances.-The largest groupof molecular compounds (apart from co-ordination compounds ofthe metals) comprises those formed by the union of substancessuch as di- and tri-nitrobenzene or picric acid with bases, aromatichydrocarbons or their derivatives.In the development of ourknowledge of this class of complex J. J. Sudborough,67 A. Werner,68and P. Pfeiffer 69 took prominent parts.The problem of their structure is a difficult one : but it is clearfrom a general review of the facts that, if they are formed by mutualco-ordination of the components, the hydrocarbon or base is thedonor molecule and the nitro-compound the acceptor. 7O Theirdepth of colour is in general roughly parallel with their stability 7land the influence of polar groups substituted in either componentis consistent with this view.A further illustration of this point is provided by the series ofcompounds described by C. A.Buehler and his colleagues fromm-dinitrobenzene, 2 : 4-dinitrotolueneJ 2 : 4-dinitrophenol, andchloro- and bromo-2 : 4-dinitrobenzenes with a series of bases,63 R. Robinson, J., 1925,127, 768; A., 1925, ii, 606.61 E. Cherbuliez, Helv. Chim. Acta, 1923,6, 281 ; A., 1923, i, 452. Comparc6 5 F. de Carli, Atti R. Accad. Lincei, 1929, [vi], 10, 186, 250, 372; A . , 1930,66 W. F. Wyatt, Trans. Faraday SOC., 1929, 25¶ 43; A., 1929, 254.G 7 J . , 1901, 79, 622; 1910, 97, 773; 1916,109, 1339.6 8 Ber., 1909, 42, 4324; A., 1910, i, 20.70 G. M. Bennett and G. H. Willis, Zoc. cit.7 1 P. Pfeiffer, op. cit., p. 348.I. Masson, J., 1931, 3200.26, 284.60 op. citORGANIC CHEMISTRY .-PART 11. 135hydrocarbons and naphthols. 72 The stability of the productsdiminishes with substitution in the dinitro-compound in the orderCl>Br > OH>H >Me >NH2.p-Chloronitrobenzene also combineswith cc-naphthol.Other recent additions to the list of such compounds are severalfrom tetryl with aromatic hydrocarbon^,^^ a compound of 1 : 3 : 4 : 5-tetranitrobenzene with benzene (1 : 1),74 and of 4 : 4'-dithiolarseno-benzene with picric acid (1 : 2).75 Others are mentioned in thediscussion below.The stability of such complexes in solution has been the subjectof repeated investigation. R. Behrend in 1894,76 by measuringthe joint solubilities of anthracene and picric acid in alcohol a t25", found a dissociation constant for the compound of 4-7-57;and the union of picric acid and p-naphthol was studied in a similarmanner.77 Determinat'ions of freezing points of solutions of thecomponents in nitrobenzene by F.S. Browsl 78 show a dissociationconstant for naphthalene picrate of 0.23 and for naphthalene-s-trinitrobenzene of 0.46. The free energy of formation of the formercompound was calculated to be 2080 cals. per mol., which agreeswell with the value 2150 cals. found by J. N. Bronsted fromdeterminations of E.M.F. in the system naphthalene-picric acid-potassium chloride-hydrochloric acid-~ater.7~The same question has been examined by H. von Halban andE. Zimpelmann 80 by the photoelectric determination of the absorp-tion of light in solutions of various concentrations at more thanone temperature. The following values of the heats of formation(&) and the equilibrium constants ( K ) at 25" were found :Compound.Solvent. Q (cals.). K.Acenaphthene-s-trinitrobenzene ... Tetrachloroethane 2450 0.41Acenaphthenem-dinitrobenzene ... Y f 1350 3-15Acenaphthene-picric acid ......... 9 , 950 0.50Anthracene-picric acid ............... Chloroform 3990 0.2272 C. A. Buehler with A. G. Heap, J . Amer. Chem. SOC., 1926,48,3168; withA. Hisey and J. H. Wood, ibid., 1930, 52, 1939; with C. R. Alexander andG. Stratton, ibid., 1931, 53, 4094; A., 1927, 141; 1930, 905.N. N. Efremov and A. M. Tichomirova, Ann. Inst. Anal. Phys. Chem.,1928, 4, 65, 92.74 A. F. Holleman, Rec. trav. chirn., 1930, 49, 112, 501; A., 1930, 333, 900.75 S. Krishna and R. Krishna, J . Indian Chem.Soc., 1929,6,665; A., 1929,76 2. physikal. Chem., 1894, 15, 183; A., 1895, ii, 71.' 7 B. B. Kuriloff, ibid., 1897, 23, 90, 673; A., 1897, ii, 397, 484.78 J., 1925, 127, 345; A., 1925, ii, 296.7 9 2. physikal. Chem., 1911, 78, 284; A., 1912, ii, 20.80 Ibid., 1925, 117, 461; A., 1926, 25.1320136 BAKER AND BENNETT :A precise investigation of such equilibria by the partition methodhas recently been published by T. S. Moore, F. Shepherd, and E.Goodall,sl who have examined a range of substances wide enoughto reveal the effects of substitution. Compound formation betweenpicric acid and a series of aromatic substances in chloroform a t18" is calculatled from indirect determinations of the free picricacid present. The latter is found by observing the concentrationin an aqueous phase in contact with the chloroform.Similarlywith aniline and a series of aromatic substances in chloroform a t25", the aniline in the water phase being determined bromometric-ally. The assumption of (1 : 1)-combination gives good equilibriumconstants K . A relatively small effect which the added substancesexert on the partition curves is studied and is expressed by the''. depression constants " below.K .Benzene ... 0.09Toluene ... 0.12o-Xylene ... 0.16p - ,, ... 0.16Mesitylene 0.18Tetrahydro -naphthalene 0.26?I%- ,, ... 0.14Picric Acid Cmpounds.K .Bromobenzene ...... 0.09 Nitrobenzene ......o-Dichlorobenzene 0.10 m-Dinitrobenzene ...... P- 9 7 0.03 o-Nitrotoluenea-Bromonaphthalene 0-23 p- ......a-Methylnaphthalene 2.76 s-Trinitrotoluene ...8- ?, 3-44 NitronaphthaleneY YNaphthalene .........2.17 2 : 4-Dinitrotoluene...Aniline Cmpounds.K .Nitrobenzene ..................... 0.01 m-Dinitrobenzene ........................ ............... Y , a-Nitronaphthalene 0.02 P-p-Chloronitrobenzene ......... 0-03 2 : 4-Dinitrotoluene ............m-Bromonitrobenzene ......... 0.06 1 : 6-Dinitronaphthalene ......s-Trinitrotoluene ...............K.0.561.030.410.570.671.021.02K.0.170.180.150.570.56Depression Constants.Picric acid. Aniline.Hexane ... 0-54 o-Nitrotoluene ...... 0.01 a-Bromonaphthalene 0.06Hexachloro- Toluene ............... 0.12 Naphthalene ......... 0.07benzene 0.38 p-Xylene.. .............0.15 o-Dichlorobenzene 0.06Carbon tetra- a-Methylnaphthalene 0.09 p-Dichlorobenzene 0-06chloride 0.27 j3- 9 9 0.09 Bromobenzene ...... 0.06The depression constants may be regarded as minor influenceson mutual solubility arising from differences of polarity among thesubstances, and the smaller values of K in the aniline series maybe attributed to increases of solubility arising in a similar way,although some would regard the colour produced as evidence ofcombination. With di- and tri-nitro-compounds the authorsregard the K values as representing combination of the aniline.cycloHexane 0.48 p - ...... 0-02 Carbon tetrachloride 0- 10 9 7*1 J., 1931, 1447; A , , 949ORGANIC CHEMISTRY .-PART If. 137In the picrate series the naphthalenes combine more than thebenzenes and the union is increased by methyl groups but dimin-ished by chlorine atoms in agreement with the general conclusion(p. 134) as to the function of the components.There is, however, a large increase of combination evident whenone or more nitro-groups are introduced into the molecule, althoughthe converse result might have been expected from the oppositepolar nature of the methyl and the nitro-group.The solutionsin these cases, nevertheless, show relatively little colour. A paleyellow compound of picric acid with nitronaphthalene was isolated(previously detected from the freezing-point curve).82The authors ascribe the different type of union here involvedto mutual dipole association of nitro-groups in the two substances. 83It is equally possible to attribute the union to the basic propertyof the nitro-group as exhibited in nitrobenzene sulphate (p.134).The stability and conditions for isolation of solid molecularcompounds have been discussed by 0. Dimroth 84 and E. Bamberger.For the reaction A + B e C, they write the equilibrium constantK = [C]/[A][B] = G . c/ab, in which a, b, and c are the solubilitiesof A, B, and C in a given solvent, and G is a stability constant forthe crystalline molecular compound C which is independent of thesolvent used. a! may also be written as Xc/XA. SB, where Xc, XA,and SB are the degrees of saturation of the compounds C, A, and Brespectively. This law is verified for anthracene picrate with thesolvents alcohol, chloroform, ether, petroleum, and carbon tetra-chloride.It leads to a precise statement of the conditions underwhich a solvent causes the decomposition of a molecular compound.No decomposition occurs when the quotient (solubility of the moresoluble component)/(solubility of the less soluble component) < G.By determining the free picric acid in a small volume of waterin equilibrium with partly decomposed compounds, the followingrelative order of increasing stabilities is found for a series of picrates :benzene < fluorene <anthracene <indene < phenanthrene < naphthal-ene <acenaphthene < a-methylnaphthalene < p-methylnaphthalene.The problem of formulating these substances has attractedconsiderable attention. Werner 85 argued that the nitro-group is82 P.L. Jovinet, Mdm. Poudres, 1928,23, 36; A., 1928, 1085.83 The freezing-point curve of nitrobenzene with m-dinitrobenzene has mean-while revealed the existence of an unstable (1 : 1) compound, and that ofnitrobenzene and 8-trinitrobenzene a (2 : 1) compound (D. L. Hammick,L. W. Andrew, and J. Hampson, J., 1932, 171).84 Annalen, 1924, 438, 67; A., 1925, ii, 36.85 LOC. cit. The argument from colour development would indicate combin-ation of tetranitromethane with a wide range of unsaturated or basic sub-stances; see E. M. Harper and A. K. Macbeth, J., 1915, 107, 87, 1824.E 138 BAKER AND BENNETTa point of attachment, since aliphatic nitro-compounds such astctranitrometbane and hexanitroethane yield similar complexes.Definite structural formuh for the base-nitro-compound complexeswere discussed by Sudborough in his earlier papers, but in 1915 86he adopted the residual valency conception of P.Pfeiffer, whichmay be represented by the typical formuh C,H,(NO,), . . . C&,and C,H3(N02), . . . . C,,H,*NH,. This was also supported byJ. Kenner.87The idea that a more precise formulation should be possiblehas been recently revived 88 and it is suggested that the unionmust be through a single nitro-group, any others present in thesame molecule having an indirect reinforcing effect. In support ofthis it was shown that, although molecular compounds of mono-nitrobenzenes (excepting nitrophenols) have hitherto been prac-tically unknown, the substances (I) and (11), in which the nitro-group is similarly reinforced by other electron-attracting groups,do yield such complexes.0Ar-N<NO2$ 0NR3(11.) (111.)The nitro-compound is regarded as united to an amine throughthe basic nitrogen atom as suggested by Werner and the union isnow formulated as in (111).Combination with hydrocarbons isregarded as occurring with one ethylene bond in the polarisedform - 1.. 'H-CH-. The occurrence of 1 mol. of ethylene or ofbenzene in metal co-ordination compounds such as [PtCl,,NH3,C,H,],[Ni(CN),,NH3,C6H6], and the nickel cyanide complex mentionedon p. 132, points definitely to the provision of one covalency by onemolecule of ethylene or one benzene nucleus.The behaviour of dinitrobenzenes with ammonia should havesome bearing on the question of structure here involved.W. E.Garner and his colleagues have found 89 that m-dinitrobenzenecombines slowly with (anhydrous) ammonia, the complex thenrapidly ionising to give a coloured negative ion containing theorganic substance. The nature of the positive ion is less clear,but it is regarded as NH, or N,H,. . .@86 L O C . cit.8 7 J. Kenner and M. Parkin, J., 1920,117, 855.88 G. M. Bennett and G. H. Willis, Zoc. cit.M. J. Field, W. E. Garner, and C. C. Smith, J., 1925, 127, 1227; W. E.Garner and H. F. Gillbe, J., 1928, 2889; A., 1925, ii, 792; 1929, 29ORUANIC CHElKIS”RY.-PruzIT 11. 139The question of the structure in the crystals of these molecularcompounds has, been attacked by the X-ray method 90 and it hasbeen shown that they have crystal lattices distinct from those oftheir components.Suggestions are made as to the arrangement ofthe units, but the positions of the atoms have not been determined.The formation of distinctf yellow and red isomeric compoundsof picric acid or dinitrophenols with halogenated amines is termedby E. Hertel ‘‘ complex isomerism ” and the substances are formul-ated as [(NO,),C,~*O][NH,Ar] (yellow) and HO*C,H,(NO,), . . . .ArNH, (red).s1The production of colour in the formation of molecular compoundsis a circumstance which has been of considerable importance intheir study. Mention may be made of some observations on halo-chromism in chalkone derivatives 92 and in styrylquinoxalines 93and of a recent theory of the probable origin of colour in quin-h ydrones .94The Bile Acids.(Continued from ,4nn. Reports, 1928, 25, 163.)9 QImportant modScations in the formulze of all the cholane deriv-atives must follow from the recent developments in this field. Thenew evidence indicates that ring I11 and probably also ring I areeach seven- instead of six-membered (compare cholanic acidformula, p. 140).The structure (111) originally assigned g5 to the tetrabasic acidC1,H,,O, obtained from pyrodeoxybilianic acid (I) through thedibasic diketo-acid C23H3406 (11) has been found to require re-vision.96 The passage from the diketo-acid (11) to (111) involvedthe shortening of the side chain by two carbon atoms, and as relatedcompounds such as choloidanic acid s7 retained their complete sidechain under similar conditions, it seemed doubtful whether (11)was actually attacked in this way.The dibasic keto-acid, C1SH220s(IV), obtained by heating the tetrabasic acid (111), was reduced byso E. Hertel, 2. physihd. Chem., 1930, [B], 7, 188; 1930, [B], 11, 69, 77;91 E. Hertel and I(. Schneider, {bid., 1930, 151, 413; L931, [B], 13, 387;O8 W. Dilthey, L. Neuhaus, and W. Schommer, J . pr. Chmn., 1929, [ii], 123,D3 G. M. Bennett and G. H. Willis, loc. cit.s4 E. Weitz, 2. Elektrochem., 1928, 54, 638; A., 1929, 190.96 H. Wieland and F. Vocke, 2. physiol. Chent., 1928, 177, 68; A., 1928,O * Idem, &id., 1930,191, 69; A., 1930, 1436.9 7 Ann. Reports, 1927,24, 137.A., 1930, 668; 1931, 153.A., 210, 1114.235; 1930, [GI, 124, 81; A., 1929, 1300; 1930, 604.1007. Compare Ann.Reports, 1928,2!5, 160140 BAKER AND BENNET*:Me Me0- & ~ C ~ & f e * ( C H , ) , * C O , HL-- Lo\/Cliolanic acid (1928) (I.) Pyrodeoxybilianic acid(11.) Dibasic C ,,-diketo-acid(V.) Tribasic C,,-acid (IV.) Dibasic CIS-ke to -acid (111.) Tetrabasic C,,-acitlMe(VIII.) [ = (V) corrected]k 2 H \ '2E:CO2H(vI.) [= (IV) corrected]J. (VII.) [ = (111) corrected]MeI /'IA, (IX.) I ' ICO,H CHMe*(CH,),-CO,H?U Me1Me /rI ICHMeC0,H (CH,),*CPh,*OH HO=CPh, (CH,),*CPh,.OHJ.Mep32-q-CH2~ x I I . l ~ ! - > 3 CH, \ / CH-CH>CH2 \ +- f d; (XIII.)QH CHMe*CO,H CHMe8FG02H CPh,-OH (XIV.) OH*CPh, CH,*CO,ORGANIC CHEMISTRY.-PART n.141Clemmensen’s method to the dibasic acid CI5Hz4O4 (IX), and thelatter converted by the action of phenylmagnesium bromide on itsester into an acid tertiary alcohol (X) and a ditertiary alcohol (XI).The acid carbinol was oxidised to the dibasic acid C,4H2204 (XII),whilst the ditertiary alcohol yielded the diphenylcarbinol deriv-ative (XIII) of this acid. In either case a repetition of the Grignardand oxidation processes led finally to the carbinol acid (XIV)(derived from an acid C13H2,04). This shortening of the side chainby one carbon atom at a time would be impossible if the dibasicketo-acid had structure (IV), but the alternative structure (VI)with side chain longer by 2CH, groups is in complete agreementwith these results. If structure (VI) be accepted for the acidC15H2205, the tetrabasic C,, acid must be (VII), not (111), and thetribasic acid C,,HzoO6 must be (VIII) instead of (V).The occurrenceof n-butane-aryy-tricarboxplic acid together with (VII) in theoxidation products from the dibasic diketo-acid (11) is equallywell accounted for by the new formulae, which explain more readilythe simultaneous production of a-methylglutaric acid.Since the acids (VI), (VII), and (VIII) have two more carbonatoms in the side chain than was originally supposed, there mustbe a hydrogen atom and not an ethyl group in position 10 in thesecompounds. This, however, leaves C2H4 unaccounted for in theformule of the dibasic diketo-acid C,H,,O, and all related sub-stances. Two possibilities are discussed by the authors to meetthis difficulty.The less probable assumption is that in the courseof the oxidation of (11) a 10-ethyl group migrates to some otherpart of the molecule and is then oxidised away. The alternativeconclusion seems almost inevitable, namely, that the missing atomsform part of ring 111 of the cholane skeleton. It has not beenrigidly proved that this ring is six-membered : the availableevidence is consistent with its being one of 7 carbon atoms.In the first place the suggestion adopted was that a CHMe groupwas inserted between C,, and CIz so that (I) should bebut later work has pointed to the CHMe group being between C,and C,, whereby rings I and I11 will both be seven-membered.The first indication of this comes from a detailed study 98 of the98 H.Wielasd and V. Deulofeu, Z. physid. Chern., 1931,198,127; A., 841142 BAKER AND BENNETT:two dihydroxycholenic acids, C24H3804, obtained by dehydrationof cholic acid.99 Of these, one is catalytically reduced to deoxy-cholic acid, and consequently has the normal bile acid skeleton.The second (apocholic acid) is not so hydrogenated and a morecomplicated relationship seemed possible. However, the two acidsby the action of bromine yield with loss of hydrogen bromide thesame dihydroxycholadienic acid, C2,H3,04. Catalytic reductionsaturates only one of the two double bonds in this substance andthe product is very similar to apocholic acid but differs from itin rotatory power.These results are in any case inconsistent with the earlier cholicacid formula with a six-membered ring 111.For apocholic acidcannot have its double bond between C,, and C13, as it would thenbe readily reducible just as is the same bond in the cholatrienicacid from cholic acid. Nor has the other dihydroxycholenic acidan ethylenic linkage a t C12-C13, since it does not yield the chola-trienic acid by loss of water. That a double bond may have wanderedis probable, sulphuric acid and zinc chloride being the reagentsused in the reaction, but it is unlikely that it will have migratedinto another ring and consequently there must be seven membersin ring 111. suggest that the inert W. Borsche and A. R. ToddI\CH,/double bond in these acids is in fact a bridge, and they represent ringI11 in apocholic acid as (XV) with the CMe between C,, and C12.(XVII.)HO-CHOn the other hand, H. Wieland and V. Deulofeu prefer the formuh(XVI), (XVII), and (XVIII) for apocholic acid, dihydroxycholenicacid, and dihydroxycholadienic acid respectively. The environ-ment of the central double bond explains its inertness.55, 2302; A., 1921, i, 865; 1922, i, 1027.9g F. Boedecker and H. Volk, Ber., 1920, 53, 1852; 1921, 54, 2489; 1952,1 2. physiol. Chem., 1931,197, 173; A., 841ORGANIC CHEMISTRY .-PART II. 143upoCholic acid yields by loss of water on heating a cholatrienicacid in which, again, one tlouble bond resists hydrogenation. Alittle cholanic acid was, however, detected which suffices to confirmthe normal carbon skeleton of these substances.A closer examination of pyrocholoidanic acid has, moreover,2provided evidence that ring I is seven-membered. It is not a keto-anhydride acid as hitherto assumed (XIX) but a keto-lactonic acid.(XIX.) WX.) (XXI.)Titration with cold alkali reveals a second carboxyl group (be-sides that in the side chain), and hot alkali three : diazomethane,moreover, yields a dimethyl ester.The dehydration thus involvesonly one carboxyl group and if the keto-acid (XX) is first formed,the keto-lactone structure (XXI) seems probable. But this formulais contrary to Bredt's rule that a double bond is not stable adjacentto the bridge head of a bridged six-membered ring.3This difficulty is overcome by the use of the new formula so thatcholoidanic acid is (XXII) and the pyro-acid is (XXIII).1 CHMel C Me 1A (XXII.) 1 \ I / CO,H CH-C*CH,-CO,H ? F*CH2*Co2H91 V=zQ (XXIII. )0 CH2\ /€I02C*CH2---6H*C02Hv coThe formation of two stereoisomerides is also accounted for.These corrections are fundamental and further evidence will soon,it may be hoped, allow of a permanent revision of all the formulaein the cholane group.Ergosterol.(Continued from Ann.Reports, 1927, 24, 148.)Chemical investigation of the phytosterols has been principallyconcerned with ergosterol 4 on account of the connection betweenH. Wieland, L. Ertel, and W. Schonberger, 2. physiol. Chem., 1931, 197,31 ; A., 841.J. Bredt, H. Thouet, and J. Schmitz, Annalen, 1924, 437, 1 ; A. Windausand A. Bohne, ibid., 1925, 442, 7; A., 1924, i, 643; 1925, i, 552.4 Other sterols : see Ann.Repwts, 1929, 26, 211, and H. Wieland, withM. Asano, Annalen, 1929,473, 300; with G. A. C. Gough, ibid., 1930,482, 36;with W. M. Stanley, ibid., 1931, 489, 31; F. Reindel and A. Weichmann,ibid., 1930,482, 120; H. Sandqvist and J. Gorton, Ber., 1930, 63, [B], 1935;A., 1929, 1200; 1930, 1431; 1931, 1164; 1930, 1578, 1431144 BAKER AND BENNETT:this compound and vitamin-D, the latter having been isolated as acrystalline isomeride of the steroL5Ergosterol, obtained from yeast, is purified as the acetate or thebenzoate.6 Its molecule, C2,H420, contains four rings, a hydroxylgroup, and three double bonds. Complete reduction yields ergo-stane, C27H48, a hydrocarbon isomeric but not identical with thesimilar products from cholesterol, coprosterol, and sitosterol.Thecarbon framework is shown to be similar to that of cholesterol bythe observation of 0. Diels and A. Karstens that the main productsof dehydrogenation of ergosterol with selenium are the same twocrystalline hydrocarbons, CIsH16 and C25H24, previously found asdehydrogenation products of cholesteryl chloride. It is thereforeprobable that ergostane is a stereoisomeride of cholest ane. Thereare, indeed, indications that cholesterol may be converted intoergosterol by heat and the saturated derivative of sitosterol isequally closely related.lOOxidative degradation of ergosterol has yielded few resultsowing to the extreme sensitiveness of the sterol to all reagents :it absorbs oxygen (5 atomic proportions) from t'he air.6 F.Reindeland K. Niederlander 11 have, however, isolated a tribasic acid,C,H,(C02H)3, from the products of oxidation with nitric acid.This appears t o be a cyclopentadiene derivative arising from a&membered ring in the nucleus. An aldehyde, C,H,,*CHO, wasalso obtained by ozonisation, which yields on oxidation a methyl-glutaric acid, and points to the group >C:CH*CH,*CH,*CHMe, inthe side chain of ergosterol.When the sterol is catalytically reduced, two molecular pro-portions of hydrogen are added to give ergostenol, C2,H4,0, ortlhree with formation of the completely saturated ergostanol,C27H480.127 l3, 14Compare Biochemistry section of this report, p. 212.R. K. Callow, Biochem J ., 1931, 25, 79; A., 618.A. Windaus and W. Grosskopf, 2. physiol. Chem., 1922,124, 8 ; A., 1923,i, 75; F. Reindel and E. Walter, Annalen, 1928, 460, 212; A., 1928, 295.Compare 0. Diels, W. Glidke,and P. Kording, ibid., 1927, 459, 1 ; A., 1928, 169.F. C. Koch, E. M. Koch, and I. K. Ragins, J. BioZ. Chem., 1929, 85, 141 ;H. B. Lemon, ibid., p. 159; A., 1930, 256, 257; R. Schonheimer, Naturwiss.,1930,18, 881 ; A., 1930, 1577.lo F. S. Spring, J., 1930, 2664; A . , 219.l1 Annalen, 1930, 482, 264; A., 1930, 1578.l2 F. Reindel and E. Walter, Annalen, 1928, 460, 212 ; I. M. Heilbron andW. A. Sexton, J., 1929, 921; A., 1928, 295; 1929, 809.l3 F. Reindel, Annalen, 1928, 460, 131; A., 1928, 295.l4 F. Reindel, E. Walter, and H. Rauch, Annulen, 1927, 452, 34; I.M.Heilbron and F. S. Spring, J., 1929, 2806; A., 1927, 241 ; 1930, 210.* Annalen, 1930, 478, 129; A., 1930, 470ORGANIC CHEMISTRY .-PART 11. 145A significant observation is the production of a dibasic acid,C25H44( CO,H),, when ergostanol (allo-a-ergostanol = hexahydro-ergosterol) is oxidised with chromic acid 13 to the ketone ergostanone.This acid when heated gives a ketone, C26H440, by loss of carbondioxide and water, which points t o the rupture in the first placeof a six- or seven-membered ring.In connexion with vitamin-D the study of various isomeridesof the sterol is of the greatest importance, and a large number ofexperiments in this direction have been recorded of which a shortaccount will now be given. The changes in structure no doubtinvolve movements in position of the double bonds and changes insteric arrangement of more than one kind.The location of thepoints of unsaturation is a matter of difficulty, and the conclusionsso far reached must be regarded as tentative.Isomeric change in ergosterol was fist brought about by theaction of hydrogen chloride upon its acetate,l* the product, ergo-sterol-B (isoergosterol), being obtained in several stereoisomeric forms(ergosterols B,, B,, and B3). The only effect here is an alterationin position of the double bonds or possibly conversion of a cis-into a trans-configuration with respect to a double bond in the sidechain ; 15 for the products all yield the same perhydro-derivative.The addition of two atoms of hydrogen (sodium and alcohol) l6and their removal at another point by means of mercuric acetateor perbenzoic acid 173 1% 2o yields ergosterol-D : these operations ininverse order furnish ergosterol-P ; 18 and yet another isomeride,ergosterol-E, has been described as resulting from the combinationof these processes with the hydrogen chloride treatment.19 Adifferent series of compounds arises when the sterol is convertedby mercuric acetate into its dehydro-derivative and this is subjectedto the catalytic action of finely divided nickel at 220°.20 Theproducts, ergostatrienone-D and u-ergostatrienone, yield onreduction ergosterol-D and the new isomeride u-ergostatrienol.In the study of the irradiation of ergosterol with ultra-violetl5 A.Windaus, K.Dithmar, H. Murke, and F. Suckfull, Annakn, 1931,1* A. Windaus and J. Brunken, ibid., 1928, 460, 225; A., 1928, 424.l7 A. Windaus and A. Luttringhaus, ibid., 1930, 481, 119; A., 1930,1178.l* A. Windaus, W. Bergmami, and A. Luttringhaus, ibid., 1929, 472, 195 ;A. Windaus, W. Bergmann, and H. Butte, ibid., 1930, 477, 268; A., 1929,1065; 1930, 338.Is I. M. Heilbron, F. Johnstone, and F. S. Spring, J., 1929, 2248; A., 1929,1442.2O A. Windaus and E. Auhagen, Annalen, 1929, 472, 185; A., 1929,1065.488, 91 ; A., 1061146 ORGANIC CHEMISTRY.-PART 11.light, two physiologically inactive sterols, suprasterols I and 11,have been isolated besides the vitamin-D.21Certain sterols undergo isomerisation when heated with sodiumethoxide in ethyl alcohol at ZOO": this results in the productionof epi-derivatives (in which the configuration of the >CH*O€I groupis inverted), hydrogenation of a double bond occurring to some extentat the same time.15 Finally, the production of isomerides by suc-cessive dehydration and hydration l5 and by the action of benzoylchloride, followed by hydrolysis (ergosterol-C),2O has not yet beenthoroughly investigated.The isomerides B, D, E and F all retain their three double bondsand are reducible to ergostanol.Like ergosterol itself, they giveinsoluble addition compounds with digitonin. A second group ofsubstances is not precipitated by digitonin, but is converted byheating with sodium ethoxide into members of the first group.They are reduced catalytically to epiergostanol, the relationshipof which to ergostanol is evident from their oxidation to the com-mon ketone ergostanone.A third group, including u-ergosteroland the products of irradiation, is not precipitated by digitonineither at once or after heating with sodium ethoxide. These iso-merides also still have three double bonds but on complete hydro-genation they yield neither ergostanol nor epiergostanol. It is asyet uncertain whether the difference here is of a steric kind or oneinvolving a change in the structure of the carbon skeleton.A number of attempts have been made to define the exact posi-tions of the double bonds in ergosterol and its isomerides, but thisproblem has not yet been solved. One argument 22 used is basedon the similarity of the absorption spectra of ergosterol and ofcholesterilene, C27H44, a dehydration product of cholesterol, butapart from the uncertainty of such evidence it cannot yet beclaimed that the structure of this hydrocarbon has been deter-mined beyond doubt. It may be taken as certain, however, thatconjugated double bonds are present in ergosterol, dehydroergo-sterol, ergosterol-B,, -D, and -F, dehydroergosterol, the two supra-sterols, and vitamin-D-all of which combine with maleic anhydride.23The isolation of the vitamin will no doubt lead to a still morerapid development of t'he chemistry of ergosterol and the furtherresults will be awaited with great interest.J.W. BAKER.G . M. BENNETT.21 A. Windaus, J. Gaede, J. Koser, and G.Stein, Annalen, 1930, 483, 17;22 I. M. Heilbron, R. A. Morton, and W. A. Sexton, J., 1928,48, 347; A. C.z3 A. Windam and A. Luttringhaus, Ber., 1931, 64, [B], 860; A., 840.A., 1577.Bose and W. Doran, J., 1929, 2244; A., 1928, 219, 410; 1929, 1432ORGANIC CHEMISTRY.-PART III. 147PART 111 .-HETEROCYCLIC DIVISION.Oxygen Ring Compounds.THE past year has produced another crop of important develop-ments in the chemistry of those natural products which containan oxygen atom as part of a heterocyclic system.Although previous investigations have made it clear that scopo-letin, which has been isolated from several different natural sources,has the structure (I), its synthesis from 2 : 4-dihydroxyanisole isnot without interest. The latter compound was transformed firstinto 2 : 4-dihydroxy-5-methoxybenzaldehyde (11) by condensationwit'h hydrogen cyanide in ether in Dhe presence of zinc cyanide andhydrogen chloride, and then into O-acetylscopoletin by heating with(1.) (11.) (111.)sodium acetate and acetic anhydride.Hydrolysis led to scopoletin,identical with the naturally occurring substance. A similar seriesof reactions starting from 2 : 5-dihydroxyanisole led to 6-hydroxy-7-methoxycoumarin (aesculetin monomethyl ether) .2 The latterproved to be identical with the product derived from the hydrolysisof aesculin methyl ether, so that the position assigned to the glucoseresidue in axculin (111) is thus confirmed.The problem of determining the exact positions occupied by thehydroxyl or methoxyl groups in natural products belonging t o theflavone and related types is frequently one of great difficulty,largely because the synthetical methods employed are not alwaysfree from ambiguity.Considerable doubt has recently existedconcerning the validity of the formulae previously assigned tobaicalein and wogonin, two flavones which have been isolated fromthe roots of Scutelluria bairnlensis. The view that baicalein is5 : 6 : 7-trihydroxyflavone (IV) rested upon the fact that it isapparently identical with the compound obtained by G. Bargellini 51 F. S. H. Head and A. Robertson, J., 1931, 1241 ; R. Seka and P. Kallir,Ber., 1931, 64, [I?], 909; A., 737.2 R. Seka and P. Kallir, ibid., p. 622; A., 606.a F . S. H. Head and A.Robertson, J., 1930, 2434; Ann. Reports, 1930, 27,4 K. Shibata, S. Iwata, and M. Nakamura, Acta Phytochim., 1923, 1, 105;178.L4., 1923, i, 591.Gazzetta, 1919, 49, ii, 47; it., 1919, i, 545148 PLANT :by the action of hydriodic acid on 2 : 3 : 4 : 6-tetramethoxy-w-benzoylacetophenone. The 'constitution accorded to Bargellini's0 RO 0 Me0(W. ) (V.) (VI. 1product, for which there were at first two alternatives, depended,however, upon the fact that it differed from a hydroxychrysin whichhad been regarded as 5 : 7 : 8-trihydroxyflavone (V; R = H).Wogonin (a dihydroxymethoxyflavone) has been demethylated toa trihydroxyflavone which is not identical with baicalein, and itsdimethyl ether was found to be different from baicalein trimethylether.' Furthermore, by heating 2 : 3 : 4 : 6-tetramethoxyaceto-phenone with aluminium chloride and treating the product-supposed to be 2-hydroxy-3 : 4 : 6-trimethoxyacetophenone (V1)-with benzoic anhydride and sodium benzoate, wogonin dimethylether was obtained.Wogonin has been regarded, therefore, as5 : 7-dihydroxy-8-methoxyflavone (V; R = Me). It has becomeapparent, however, that hydroxychrysin cannot be 5 : 7 : 8-tri-hydroxyflavone, and, furthermore, the evidence for the structuresassigned to baicalein and wogonin became less sound when it wasreported a few months ago * that the substance (VI) was in reality6-hydroxy-2 : 3 : 4-trimethoxyacetophenone. More recently, how-ever, it has transpired that the latter observation was unsound, andfurther work9 has now confirmed the nature of (VI) and estab-lished definitely the structures of the natural products.Antiarol(3 : 4 : 5-trimethoxyphenol) was transformed into its ethyl etherand then converted into 2-hydroxy-3 : 4-dimethoxy-6-ethoxy-acetophenone (VII) by the action of acetyl chloride and aluminiumchloride. The position of the hydroxyl group was confirmed bythe coloration which is developed with ferric chloride. After treat-ment with benzoic anhydride and sodium benzoate, followed byde-alkylation, 5 : 7 : 8-trihydroxyflavone was obtained. It provedto be identical with the demethylation product of wogonin, and itnecessarily follows that baicalein is correctly represented by theformula (IV). A re-investigation of Bargellini's synthesis of thelatter substance has indicated, however, that it is by no means as6 M.Nierenstein, Ber., 1912, 45, [B], 499.* K. Shibata and S. Hattori, J . Pharm. Xoc. Japan, 1931, 51, 15; Chem.0 S. Hattori, Acta Phytochim., 1931, 5, 219.S. Hattori, Acta Phytochim., 1930, 5, 99; A., 493.Zentr., 1931, i, 3358ORGANIC CHEMISTRY.-PUT fII. 149satisfactory as it appeared to be, for it has been reported thatt,he reaction leads more frequently to the isomeric 5 : 7 : 8-trihydr-oxyflavone. Similarly the action of hydriodic acid on 2 : 3 : 4 : 6-Me0 0EtOt etramet hoxy - a-anisoylacet ophenone, which Bargellini l1 has em -ployed for the synthesis of scutellarein (VIII; R = H), is statedto yield mainly 5 : 7 : 8 : 4'-tetrahydroxyflavone, the structure ofwhich was confirmed by the anisoylation and subsequent demethyl-ation of (VI).Further conhmation for the structure assigned tobaicalein is derived from the fact that its trimethyl ether yieldsantiarol, in addition to benzoic acid and acetophenone, when boiledwith aqueous potassium hydroxide for several hours.It has recently been reported l2 that the anisoylation of 2 : 4-di-hydroxy-3 : 6-dimethoxyacet ophenone (IX) proceeds normally andthat the product obtained on subsequent demethylation is5 : 7 : 8 : 4'-tetrahydroxyflavone (X). These observations are in-compatible with earlier statements 13 to the effect that the reactiontakes an unexpected course resulting in partial demethylation andthe formation of (VIII; R = Me), and the ultimate synthesis, onMe0 HO 0further demethylation, of scutellarein.Portunately the constitu-tion assigned to scutellarein is not involved in this ambiguity, sincealternative syntheses have been developed.The structure allotted to citronetin, a compound obtained bythe hydrolysis of the glucoside citronin, has been confirmed14 bythe use of a reaction which has previously been employed forsynthesising fla~an0nes.l~ The action of o-methoxycinnamoylchloride on phloroglucinol in nitrobenzene in the presence ofaluminium chloride yielded, among other substances, 5 : 7-di-lo S. Hattori, loc. cit.l1 Gazzetta, 1915, 45, 69; A., 1915, i, 84.l2 S. Furukawa and H. Tamaki, Chem. Zentr., 1931, ii, 2161.l3 F. Wessely and G. H. Moser, Monatsh., 1930,56, 97; Ann.Reports, 1930,14 3. Shinoda and S. Sato, Chem. Zentr., 1931, ii, 2326.l5 See Ann. Reports, 1928, 25, 169.27, 174150 PLANT :hydroxy-2’-metlhoxyflavanone (XI), which proved to be identicalwith the natural product.Further interesting observations have been made regarding theconversion of quercetin (XII) into cyanidin (XIII). Thus, whilethe action of sodium amalgam in alkaline solution on quercetinpent amethyl ether leads readily to the pseudo-base of pentamethyl-H O O A V H a Me0 €IO&-&Hcyanidin, quercetin itself gives a negligible quantity of cyanidin.That the failure of the process under these conditions is due to thepresence of the free hydroxyl group in the 3-position is madeprobable by the fact that a good yield of cyanidin chloride is obtainedwhen similar treatment is applied to rutin (a rhamnoglucoside ofquercetin with the sugar residue in the 3-position) and the reactionmixture is heated with hydrochloric acid.16 It has also beenreported l7 that a small yield of pentamethylcyanidin chloride canbe obtained by the reduction of quercetin pentamethyl ether withtitanium trichloride in methyl-alcoholic ammonia.Of considerable interest is the isolation of several isoflavoneglucosides from the soya bean.ls One of these, which has beencalled “ genistin,” yielded, on hydrolysis, glucose and the previouslyknown genistein (XIV; R = OH).The constitution of theglucose-free product was indicated not only by the properties ofits simple derivatives, but also by alkali fission into formic acid,phloroglucinol, and p-hydroxyphenylacetic acid.An examinationof the product derived from the hydrolysis of the methylatedglucoside showed that it was 7-hydroxy-5 : 4’-dimethoxyisoflavone,from which it follows that the glucose residue in genistin is in the7-position. A second glucoside, daidzin, has given glucose and a@H2 C*OHHO co (XI.) HO CO (XII.)c1r”? 0 (XIV.)HomHQ*Ho@doH H (XIII.) R COhitherto unknown isoflavone (XIV; R = H) t o which the name“ daidzein ” has been given. Alkaline hydrolysis of the latterl6 Y . Asahina and M. Inubuse, Ber., 1931,64, [B], 1256; A., 940.1’ P. Karrer, Y . Yen, and I. Reichstein, Helu. Chim. Acta, 1930, 13, 1308;l8 E. Walz, Annalen, 1931, 489, 118.A., 233ORGANICY CHEMISTRY .-PART IU.151yielded formic acid and 2 : 4-dihydroxyphenyl p-hydroxybenzylketone, the identity of which was established by its synthesis fromresorcinol and p-hydroxyphenylacetonitrile by means of a Hoeschreaction. The glucose residue is again attached in the 7-position,since the methylated glucoside, on hydrolysis in two stages, gave2 : 4-dihydroxyphenyl p-methoxybenzyl ketone. At least one otherisoflavone glucoside has been isolated from the same source, but theexact positions of the substituents in the glucose-free material havenot yet been determined.The earlier applications of the anthocyanidin syntheses of Prattand Robinson to substances containing the glucose residue, culmin-ating in the synthesis of cczllistephin chloride,1g foreshadowed thepreparation of other flower pigments, and further extensive work inthis field has now been described.The acetylated p-glucoside (XV),from the action of dry silver carbonate on O-tetra-acetyl-or-glucosidylbromide and w-hydroxy-3 : 4-diacetoxyacetophenone (XVI) inchloroform solution, has been treated in chloroform-ether withO-benzoylphloroglucinaldehyde (XVII) and dry hydrogen chloride.OAcC 0 C ) O A c I ~ ~ ~ ( ) C 0 * C H 2 * 0 HCH,*O*C,H,O( OAc),(XV. 1 (XVI.) (XVII. )The resulting flavylium salt, on hydrolysis with aqueous sodiumhydroxide and subsequent acidification with hydrochloric acid,yielded 3-@-glucosidylcyanidin chloride 2O (XVIII ; R = H), whichproved to be identical with a specimen of chrysanthemin chloridefrom the flowers of the deep-red chrysanthemum.By a similarseries of reactions O-benzoylphloroglucinaldehyde and the tetra-acetylglucoside of the 6)-hydroxy-ketone (XIX) ultimately gave3-~-glucosidylmalvidin chloride 21 (XX), which was shown t o bec10 OR r”lidentical with cenin chloride, an anthocyaninOMec o e I OMe I (XIX.)CH2*OHfrom the skins ofpurple-black grapes. Furthermore, 3- p-glucosidylpeonidin chlor-ide 22 (XVIII; R = Me), from the tetra-acetylglucoside of o-hydr-See Ann. Reports, 1928, 25, 166.2o S. Murakami, A. Robertson, and R. Robinson, J., 1931, 2665.21 L. F. Levy, T. Posternack, and R. Robinson, ibid., p. 2701.2z L. F. Levy and R. Robinson, ibid., p. 2715152 PLANT :oxy-4-acetoxy-3-methoxyacetophenone and O-benzoylphloroglucin-aldehyde, was found to be identical with oxycoccicyanin chloride,a pigment of American ~ranberries.~~ The galactoside obtainedby the action of dry silver carbonate on w-hydroxy-3 : 4-diacetoxy-acetophenone and O-tetra-acetyl-a-galactosidyl bromide has beenconvert,ed by a similar process into 3-p-galactosidylcyanidin chlor-ide 24 (XVIII; R = H; C6Hl1O, = galactose residue), which isapparently identical with natural idaein chloride.These synthetical methods have been further extended to thepreparation of several flavylium salts with a sugar residue in ot’herc10 OMer”?than the 3-po~ition.~~ For example, 7- p-glucosidylpelargonidinchloride (XXI) was obtained from O) : 4-dihydroxyacetophenonec10r”?and the tetra-acetyl- p-glucoside (XXII), while a related seriesof reactions gave ultimately 5- @-glucosidy Ipelargonidin chloride(XXIII), which was found t o be identical with pelargoneninchloride derived from the partial hydrolysis of pelargonin chloride.c1r”7H O & E O H(XXIII.)()EO(AcO),C,H,O*O(=I*) OBZ c6H1105*0The definite characterisation of many of these glucosides hasrevealed several very interesting generalisations. For instance,the presence of a free hydroxyl group in the 3-position renders the23 (Miss) K. E. Grove and R. Robinson, Biochem. J., 1931, 25, 1706.24 (Miss) K. E. Grove and R. Robinson, J., 1931, 2722.25 A. Leh, A. Robertson, R. Robinson, and T. R. Seshadri, ibid., p. 2672;L. F. Levy and R. Robinson, ibid., p. 2738ORGANIC CHEMISTRY.-PART III.153molecule very susceptible to attack by oxidising agents,26 so thatsuch compounds rapidly decolourise dilute solutions of ferric chloride.Thus, for example, the yellow-brown colour of a very dilute ferricchloride solution was comparatively rapidly discharged by pelar-gonidin chloride and its 4'-, 5-, and 7-p-glucosides, but was unchangedby callistephin chloride (3-p-glucosidylpelargonidin chloride), 3- p-glucosidylpeonidin chloride (XVIII ; R = Me), and luteolinidinchloride 27 (XXIV) after a much greater period of time. Analogousimportant generalisations can be drawn from a study of the dis-tribution of these substances between amyl alcohol and dilutehydrochloric acid, and also from a careful examination of theircolour reactions in a range of buffered solutions of graded pH.2*With the aid of these characteristic features it is possible to makefar-reaching deductions concerning the structures of other naturallyoccurring anthocyanins.For instance, cyanin, pelargonin, peonin,and malvin have hitherto been considered t'o be Ei-biosides, but,since there are now clear indications that there are sugar residuesin both the 3- and the 5-position, these anthocyanins must be regardedas 3 : 5-diglucosides. On the other hand, mecocyanin, prunicyanin,and keracyanin are biosides with the sugar group in the 3-position.29Furthermore, the colour reactions, etc., of the anthocyanins andanthocyanidins have been made the basis of methods for examiningand detecting the nature of the anthocyanins present in numerousc10 OH h 0flPh (XXV.)H (XXIV.) HO COflowers.30 A very interesting outcome of the latter investigationis the observation that the colours of these salts can be modifiedto a remarkable degree by the presence of other substances (co-pigments) which apparently form with them weak additive com-plexes.The actual colours of the flowers themselves may dependto a considerable extent upon this factor.Other investigations among natural products belonging to theoxygen ring types have included studies into the position of thesugar group in a few miscellaneous glycosides. Baicalin, from the26 Compare P. Karrer, R. Widmer, A. Helfenstein, W. Hiirliman, 0. Niever-gelt, and P. Monsarrat-Thomas, Helv. Chim.Acta, 1927, 10, 729.27 A. Le6n and R. Robinson, J., 1931,2732.2 8 Compare A. Robertson and R. Robinson, Biochem. J., 1929, 23, 35.29 (Mrs.) G. M. Robinson and R. Robinson, Nature, 1931,128, 413.30 (Mrs.) G. M. Robinson and R. Robinson, Biochem. J., 1931,25, 1687154 PLANT :roots of Xcutellaria baicalensis, yields glycuronic acid and baicalein(5 : 6 : 7-trihydroxyflavone) on hydrolysis, and it has now beenshown31 that the glycuronic acid residue is in the 7-position(formula XXV) from a comparison of the reactions of baicalinwith those of primetin (5 : 6-dihydroxyflavone). Thus it gives amonomethyl ether which develops a violet-brown colour with ferricchloride, indicative of a free hydroxyl group in the 5-position.Furthermore, baicalin itself , like primetin, gives a green colour withferric chloride, and is very readily oxidised.It has been con-cluded 32 that the product obtained from myricitrin, a rhamnosideof myricetin (5 : 7 : 3’ : 4’ : 5’-pentahydroxyflavonol), by methyl-ation and subsequent hydrolysis is myricetin 5 : 7 : 3’ : 4’ : 6’-pentamethyl ether (XXVI), from which it follows that the sugarresidue, as in several other flavonol glycosides, is in the 3-position.The bioside hesperidin, which yields rhamnose, glucose, and hes-0 OMe 0Me0 CO (XXVI.) HO CO (XXVII.)(XXVIII.) Ho()g%H : C H e M eMe OMeperitin (XXVII ; R = H) on hydrolysis, has been shown 33 to havethe biose residue in the 7-position (XXVII; R = C,,H2,09). Onmethylation and subsequent hydrolysis it gave 4-hydroxy-2 : 6-di-methoxyphenyl3 : 4-dimethoxystyryl ketone (XXVIII) (the flavan-one structure readily isomerises to the chalkone), which has beensynthesised by the interaction of veratraldehyde and 4-hydroxy-2 : 6-dimet hoxyacetophenone.Many int,eresting and important investigations of the methodsused for the synthesis of chromones and coumarins have recentlybeen described.The extremely valuable reaction whereby theacylation of certain polyhydroxyacetophenone derivabives leads tothe production of several chromone types3* cannot be used witho-hydroxyacetophenone itself. It has now been found,35 however,that the process can be applied to 2-acetyl-l-naphthol. 1 : 4-a-Naphthapyrones (I) result from the action of a mixture of the31 K.Shibata and S. Hattori, Acta Phytochim., 1930, 5, 117; A . , 493.32 S. Hattori and K. Hayashi, ibid., 1931, 5, 213.33 F. E. King and A. Robertson, J., 1931, 1704.34 See Ann. Reports, 1929, 26, 152.35 A. S. Bhullar and K. Venkataraman, J., 1931, 1165ORGANIC CHEMISTRY.-PART III. 155anhydride and alkali salt of the appropriate acid upon this com-pound, but the simultaneous formation of the 3-acyl derivatives (11) eo O/\ &yo O/\COR &,"(1.) (11.) (111.)is a marked feature of the process, whereas analogous carbon-acylation is very rare in the aforementioned benzene series. Thereaction can also be applied to l-acetyl-2-naphthol with the form-ation of 1 : 4-pa-naphthapyrones 36 (111) ; simultaneous carbon-acylation again occurs when acetic anhydride is used.Furtherexamples of this reaction involving the use of simpler hydroxy-ketones have been described.37 By acylation of 2-hydroxy-4 : 6-dimet hoxy propiophenone and 2 - hydroxy-4 : 6-dimethoxy-n-butyro-phenone, for example, chromones of the type (IV) have beenprepared. Acetylation of 2-hydroxy-4 : 6-dimethoxyacetophenoneunder vigorous conditions gave a product, believed to be (IV;R = Me; R' = Ac), in which acetylation in the 3-position hasapparently taken place. A further extension38 of the reaction tothe acylation of 4 : 6-diacetylresorcinol (V) has yielded the di-chromones (VI) and the chromones (VII).R R 7?The condensation of phenols with p-ketonic esters has beenextensively employed for the synthesis of both coumarins andchromones.It has previously been considered that, in general, theformer result when sulphuric acid is used as the condensing agent,and the latter in the presence of phosphoric oxide. More recentstudies 37, 39 of the reaction have shown, however, that while -the36 B. K. Menon and K. Venkataraman, J., 1931, 2591.37 F. W. Canter, F. H. Curd, and A. Robertson, ibid., pp. 1245, 1255;F. W. Canter, A. R. Martin, and A. Robertson, ibid., p. 1877.38 K. C. Gulati and K. Venkataraman, ibid., p. 2376.39 D. Chakravarti, J. Indian Chem. SOC., 1931, 8, 129, 407; A., 962, 1304;A. Robertson, W. F. Sandrock, and Miss C. B. Hendry, J., 1931,2426156 PLANT :use of sulphuric acid always leads to the formation of coumarins,when this is replaced by phosphoric oxide, the nature of the productdepends upon the particular phenol which is employed.Thus,although simple monohydric phenols and quinol yield chromones,resorcinol, orcinol, pyrogallol, phloroglucinol, phlorogl ucinol di -methyl ether, and a-naphthol give coumarins. The course of thereaction is apparently independent of the nature of the 8-ketonicester.An investigation 40 of the condensation of a-formylphenylaceto-nitrile, CHO.CHPh.CN, and benzoyloxymethylenephenylaceto-nitrile, CH(O*COPh):CPh*CN, with polyhydric phenols in dry etherin the presence of zinc chloride and hydrogen chloride has made itclear that the reaction leads, in general, t o the correspondingderivatives of 3-phenylcoumarin and not t o the isomeric isoflavones(3-phenylchromones). For instance, the use of resorcinol resultsin.the formation of 7-hydroxy-3-phenylcoumarin (VIII). Thecondensation, which involves the interaction of the cyano-groupand a phenolic hydroxyl group, is interesting, therefore, because itdoes not follow the normal course of the Hoesch reaction.It is possible in the space available to mention only a very fewof the more outstanding of the remaining points in the year's out-put of work on oxygen ring compounds. Coumarins substituted inthe 3-position can readily be converted by treatment with phenyl-magnesium bromide in dilute solution a t room temperature intothe corresponding 2-phenylbenzopyrylium salts (e.g., X from IX),but, when the reaction is carried out in hot concentrated solution,the 2 : 4-diphenyl-A2-chromens (e.g., XI) are formed.41 The formerc1(IX.) (X.> (XI.)reaction, however, gives only poor yields of the benzopyryliumsalts when applied to coumarins substituted in the 4-position, butthe more vigorous conditions lead readily t,o the production of2 : 2-diphenyl-A3-chromens (XII).Of some interest is the observation 42 that coumarone and diphenyl-40 I.0. Badhwar, W. Baker, B. K. Menon, and K. Venkataraman, J., 1931,4 1 I. M. Heilbron and D. W. Hill, J., 1927, 2005; I. M. Heilbron, D. W.42 N. A. Orlov and V. V. Tiatschenko, Ber., 1930,63, [B], 2948; A., 233.1541.Hill, and H. N. Walls, J., 1931, 1701ORGANIC CHEMISTRY.-PART IIT.. 157ene oxide are formed in good yields when the vapours of coumarinand xanthone respectively are submitted at atmospheric pressureto temperatures of 860-880".Open-chain ketones do not losecarbon monoxide to give simple products under similar conditions.The recent preparation of derivatives of acetylene oxide, inwhich there is an unsaturated 3-membered oxygen ring, is a note-worthy feature in this field. These substances resulted in pooryields by reactions analogous to those which lead to the ethyleneoxides. The action of powdered potassium hydroxide on desylPhC---CPh(CH,,,<"H2>CH2(XII.) (XIII.) (XIV.)chloride, CHPhClCOPh, in toluene has given the diphenyl deriv-ative (XIII), while the monophenyl compound has been obtainedfrom phenacyl bromide by the use of silver oxide.43 The productswere found to be comparatively stable, but gave desyl chloride andphenacyl chloride respectively when heated for two hours withconcentrated hydrochloric acid at 120".The preparation of cyclotellurobutane (tetrahydrotellurophen)(XIV; n = 2) by a process essentially similar to that previouslyused for the synthesis of cyclotelluropentane 44 (XIV; n = 3) hasbeen de~cribed.,~ The action of aluminium telluride on &tetra-[ CH,],Br C,H 8:Te*[CH,] ,*Te:C,H s(xv.) c,H,:T/ I I (XVI.)Br \Br Brmethylene dibromide led to a mixture of the telluronium salts (XV)and (XVI), which dissociated, on heating, to give tetramethylenedibromide and cyclotellurobutane.A more convenient procedurewas found by dissolving amorphous tellurium in as-tetramethylenedi-iodide at 130".The cyclotelluributane 1 : 1 &-iodide, C4Hs:Te12,which was formed was reduced by passing sulphur dioxide throughits suspension. in boiling water. cycZoTellurobutane exhibited theadditive properties characteristic of the saturated cyclic telluro-and seleno-hydrocarbons.5-Membered Nitrogen Ring Compounds.A noteworthy feature of the chemistry of pyrrole derivatives isthe recent resolution of 1 - o - carb oxy p heny 1 - 2 : 5 - dimet hy lp y rr ole -43 W. Madelung and M. E. Oberwegner, AnnaZen, 1931,480,201.44 See Ann. Reports, 1928, 25, 196.4 5 G. T. Morgan and F. H. Burstall, J., 1931, 180158 PLANT :3-carboxylic acid 46 (I) and 2 : 5 : 2’ : 5’-tetramethyl-1 : 1‘-dipyrryl-3 : S’-dicarboxylic acid 47 (11) into optically active components.ItH0,C H 0 ,C*C=CMeHCZCMe(1.1 (11.)is probable that the activity of these compounds is due to restrictedrotation similar to that observed in the diphenyl series, although itis just possible that its origin may lie in the asymmetric nitrogenatoms.The action of aliphatic diazo-compounds on pyrroles may pursuevarious courses.48 The use of diazoacetic ester has been found toresult in the introduction of the *CH,*CO,Et group into the nucleusat an a-carbon atom, if this is available, but diazo-ketones anddiazo-ketonic esters react differently. For instance, benzoyl-phenyldiazomet hane and 2 : 4-dimethylpyrrole yielded the product(111), which has apparently resulted from the intermediate formationof diphenylketen. In fact, the latter substance has been shown toadd directly to 2 : 4-‘dimethylpyrrole with the formation of (111).MeC C*CO*CHPh, MeC C*CO*CHMe*CO,Et,Hs-EMe Hg-gMev NH (IV.)v NH (111.)Similarly, diazoacetoacetic ester and 2 : 4-dimethylpyrrole reactedtogether to give the compound (IV).Ketens and isocyanic estersare stated t o combine additively with pyrroles with the formationof ketones and amides respectively.Very interesting results have also been obtained by 0. Diels,K. Alder, and their collaborators in an extension of their study ofadditive processes to certain heterocyclic systems. Furan behavedCOae(VII.)in a manner similar to that observed in unsaturated carbocyclicsystems, and with maleic anhydride yielded the product *9 (V).46 L. H. Bock and R.Adams, J. Amer. Chem. Soc., 1931, 53, 374; A., 362.4 7 C. Chang and R. Adams, ibid., p. 2353; A., 1074.4 8 C. D. Nenitzescu and E. Solomonica, Ber., 1931, 64, [B], 1924; A., 1305.49 0. Diels, K. Alder, andE. Naujoks,BeT., 1929,02, [B], 654; A., 1929, 570ORGANIC CHEMISTRY.-PART III. 159With dimethyl acetylenedicarboxylate it gave a similar substance(VI) besides a compound (VII) derived from the further additionof a second molecule of f~ran.~O In the a-pyrone series similaradditive reactions have been realised. Thus methyl coumalategave with maleic anhydride in boiling toluene the product (VIII),but in boiling xylene the reaction proved to be rather more com-plex and led to (IX).51 In the pyrrole series, however, the additive4 H L ,MeO2C.G HTCO>O CH*COyMeO,C*f(o TH \FHCO>OHC $0 CH*CO HC HYCO CHCO‘CH’ \ C H Y(VIII.) PX-1processes are of a different character and do not result in the form-ation of polycyclic derivatives. The main reactions are illustratedby the addition of maleic acid to 2-methylpyrrole with the formationof (X), or of acetylenedicarboxylic acid to 1-methylpyrrole with theproduction of (XI) .52 Certain indole derivatives closely resemblethe pyrroles in this respect, but the reactions may also be moreHc-GHHcj/c.C( C02H) :CH*CO,HHFl -P MeCQ*CH (C0,H) *CH,*C02HNH (X.) (XI.)Me C0,H MeC ‘co NHMe CO CONH NH(=I*) (XIII.)complex. For example, 2-methylindole and maleic anhydridegave not only (XII) but a, further reaction product (XIII).53 Inthe case of indole and 3-methylindole the course of the reaction wascomplicated by the primary polymerisation of the indole.The tendency for the 2 : 3-linkage in the indole skeleton to com-bine additively with OH and NO,, or 20H, which is such a markedfeature of the action of nitric acid on the N-acyl derivatives oftetrahydrocarbazole (XIV ; n = 2) and dihydropentindole (XIV ;n = l), has been found to be enormously diminished when thisso 0.Diels, K. Alder, H. Nianburg, and (Frl.) 0. Schmalbeck, Annalen,1931, 490, 243.51 0. Diels, K. Alder, and K. Niiller, ibid., p. 257.s2 0. Diels, K. Alder, and D. Winter, ibid., 1931, 486, 211; A., 849;0. Diels, K. Alder, and €3. Winckler, ibk?., 1931, 490, 267.53 0. Diels, K. Alder, and W. Lubbert, ibid., p.277160 PLANT :system is contained in more complex polycyclic types.54 Thus,of many compounds investigated, only one, viz. , 7-benzoylbenzo-pentindole (XV), was found to give an addition product (XVI) ofthe kind mentioned.(XW.) (XV.) (XVI.)The synthesis of certain compounds in which a nitrogen atom iscommon to two fused ring systems is of considerable interest inview of the probable occurrence of similar structures in somealkaloids, e.g., lupinine. When the addition product obtained from2-methylpyridine and bromoacetone was distilled in steam in thepresence of sodium hydrogen carbonate, 2-methylpyrrocoline (XVII)was obtained,55 and the reaction has been applied to other analogouscases. Pyrrocolines have also been reported from the action ofacid anhydrides on Z-met!hylpyridine, e.g., l-propionyl-3-methyl-f) =====QH f)======y*CO*CH,Me HR-9H HvH N*[CH,],;CN\\,N\//CM" N A P H CH CMe(XVII.) (XVIII.) (XIX.)pyrrocoline (XVIII) when propionic anhydride was used.56 Inaddition, potassium pyrrole has been treated 57 with P-cyanoethyltoluene-p-sulphonate, and the 1-p-cyanoethylpyrrole (XIX ; n = 2)so obtained made to undergo a Hoesch reaction with the formationof 3-keto-4 : 5-dihydrodi-(l : 2)-pyrrole (XX).Similarly, y-l-pyrryl-butyronitrile (XIX; n = 3), from the interaction of potassiumpyrrole and y-bromobutyronitrile, yielded 8-keto-5 : 6 : 7 : %tetra-hydropyrrocoline (XXI).coHY==(i-(iO H 2 ~ ~ = 7 H Hg-(iHMeH C v C ONMe(XXII.)/ HHC\/NyCH, CH H, H2cx, bii?(XX.1 (XXI.)54 S.H. Oakeshott and S. G. P. Plant, J., 1928, 1840; S. A. Bryant and5 5 A. E. Tschitschibabin, Ber., 1927,60, [B], 1607; A., 1927,885.6 6 A. E. Tschitschibabin and F. N. Stepanov, Ber., 1930, 63, [BJ, 470 ; A .5 7 G. R. Clemo and G. R. Ramage, J . , 1931, 49.S. G. P. Plant, J., 1931, 93.1930, 619ORGANIC CHEMISTRY .-PART III. 161Turning to natural products of the indole type, it is of interest torecord that an examination 5* of the basic substances which can beextracted from toad secretions goes to show that bufotenine, forwhich the structure (XXII) has previously been suggested,59 is anindole derivative of the formula (XXIII), while bufotenidine is therelated betaine (XXIV). When calycanthine, an alkaloid from-G*CH2*CH(NMe,)*C02H G-CH2-yH-70/CH Me3N-0NMe(XXIV.)o v , H NMe OT(XXIII.)CaZycanthus glaucus, was first benzoylated, and then either oxidisedwith potassium permanganate or treated with alkali, it yieldedbenzoyl-N-methyltryptamine, the constitution of which was estab-lished by its preparation from tryptamine (3-p-aminoethylindole)by the action of an excess of inethyl iodide and subsequent benzoyl-ation.On the basis of these results 6o it has been suggested thatthe alkaloid is a p-carboline derivative containing the group (XXV).It may also be mentioned that tryptophol (XXVI), derived fromthe action of yeast on tryptophan, has recently been synthesisedby the reduction of ethyl indolyl-3-acetate with sodium and alcohol.Work dealing with glyoxaline derivatives and published duringthe past two years includes the synthesis 62 of I-2-thiolhistidine (IV).This is of special interest in view of the close relationship betweenthis compound and several natural substances, and of the prob-ability that it may itself be found among the products of thehydrolysis of proteins. Natural I-histidine (I) was converted firstinto its methyl ester dihydrochloride and then, by benzoylation,into methyl ay8-tribenzamido- Av-pentenoate (11), which, withmethyl-alcoholic hydrogen chloride, gave methyl a6-dibenzamido-y-ketovalerate (111).The dihydrochloride of the correspondinga6-diamino-y-ketovaleric acid, obtained by boiling with 20%s8 H. Wieland, G. Hesse, and H. Mittasch, BeT., 1931, 64, [B], 2099; A .,1310.6B H. Handovsky, A., 1920, i, 495.6o R. H. F. Manske, Canadian J . Res., 1931, 4, 275; A., 855..st R. W. Jackson, J. Biol. Chem., 1930, 88, 659; A., 97.J. N. Ashley and C. R. Harington, J., 1930, 2586.REP.-VOL. XXVIII. 162 PLANT :hydrochloric acid, yielded, on treatment with one molecular equi-valent of sodium thiocyanate, the monohydrochloride of Z-Z-thiol-H02C*CH(NH2)*CH2*$-NH>CH MeO2C.QH--CH2*~=CH*NHBzHC-N NHBz NHBz(1.) (11.1Me02C*~H*CH2*CO*CH2*NHBz H02CoCH(NH2)~CH,o~-NH~c.~HNHBz HC-N(111.) (IV.)histidine (IV).interact ion of cc8-diamino- p - ket obut ane dihydr oc hloride,HCl,NH2*CH2*CO*CH2*CH2*NH2,HC1,and sodium thiocyanate is closely related to the above synthesis.It is noteworthy that this substance does not show to any appreciableextent the physiological properties of histamine.The preparation of 2-thiolhistamine 63 (V) by theAmong the naturally occurring glyoxalines, anserine, recentlyisolated from bird muscle-ti~sue,~~ has been shown to have theconstitution (VI).65 Thus it yielded, on hydrolysis with baryta,p-aminopropionic acid and an N-methyl derivative of dl-histidine.The relative positions of the side-chain and methyl group wereindicated by the fact that anserine gave 1 : 5-dimethylglyoxalinewhen distilled with soda-lime.Anserine differs from the closelyrelated carnosine only in having the methyl group attached to thenitrogen atom of the glyoxaline ring. When the hydrolysis iseffected by the use of 20% sulphuric acid for 6-8 hours, theseproducts yield E-methylhistidine and Z-histidine respectively.66Of interest is the preparation of 1 : Z-diphenylglyoxalino-4 : 5(3' : 2')-quinoline 67 (VII). This was accomplished by firstheating the azlactone (VIII), from the condensation of o-nitro-benzaldehyde with hippuric acid, with aniline in the presence ofcopper powder to obtain o-nitrobenzylidenebenzamidoacetanilide63 F. L. Pyman, J., 1930, 98.64 D. Ackermann, 0. Timpe, and K. Poller, 2. physiol. Chem., 1929, 183,1 ; A . , 1929, 944.e 5 W. Linneweh, A. W. Keil, and F. A. Hoppe-Seyler, ibid., p. 11 ; A.,1929, 944; F. L. Pyman, J., 1930, 183; W. Keil, 2. physiol. Chem., 1930,187, 1 ; A . , 1930, 617.G 6 W. Linneweh and F. Linneweh, 2. physiol. Chcm., 1930, 189, 80; A.,1930, 1049.6' K.S. Narang and J. N. RBy, J., 1931, 976ORGANIC CHEMISTRY.-PUT III. 163(TX). The latter gave 5-keto-1 : 2-diphenyl-4-o-nitrobenzylidene-4 : 5-dihydroglyoxaline (X) on treatment with phosphoryl chloride,N(VII.) (VIII.) (IX.)and the formation of the glyoxalinoquinoline (VII) was theneffected by reduction with zinc dust and acetic acid. A relatedNPoq--r. (XI.) 4 c o NH3duct (XI) has been obtained by the condensation of hydantoiwith o-nitrobenzaldehyde, and the reduction of the 5-o-nitrobenzyl-idenehydantoin thus formed with hydriodic acid and phosphorus.6sCyanine Dyes.-Of very considerable interest is the recentinvestigation 6g of the structure of indolenine-yellow, a dye obtainedby the action of nitrous acid on 2-methylene-1 : 3 : 3-trimethyl-indoline (I) in acetic anh~dride.~O It was originally thought thatthe substance possessed the formula (11), but it has now beenR Xshown that the reaction results in the elimination of hydrogencyanide and that the constitution of the dye is, in reality, that ofCMe, Me,Can indocyanine (111).The reaction is, therefore, very closelyrelated t o one already described 71f~r the preparation of thiocyanines.6 8 J. Kozak and L. Musiak, Bull. Awd. Polonaiae, 1930, [A], 432; A., 366.as R. Kuhn, A. Winterstein, and G. Balser, Ber., 1930, 63, [B], 3176; A.,70 D.R.-P. 459,616; Chem. Zen.fr., 1928, i, 3119.71 Miss N. I. Fisher and Miss F. M. Hamer, J., 1930, 2502 ; see Ann. Reports,238.1930, 27, 187164 PLANT :When the methylene base (I) was treated in glacial acetic acid withsodium nitrite and then with perchloric acid, the perchlorate (IV)was isolated, and this was subsequently converted into indolenine-yellow (111) by heating with a further quantity of the base (I) inacetic anhydride.The latter stage involved the loss of water andhydrogen cyanide.Another surprising new met hod for the production of thiocyanines(V) has been discovered; 72 it requires the interaction of methyl-magnesium iodide and an N-alkylbenzthiazolone (VI) in benzenesolution, and apparently involves the evolution of methane by amechanism which is not at present obvious.S S SR IThe scope of the +-cyanine reaction (the action of alkali on amixture of the alkyliodides of 2-iodoquinoline and quinaldine) ,which has already been applied to the preparation of numerousFrom 2-iodopyridinealkyliodide and quinaldine alkyliodide, the 4-cyanines (VII) wereobtained, while the analogous dyes (VIII) resulted from a similarreaction with 2 -iodo- p-napht haquinoline alkyliodide and p -napht ha-quinaldine alkyliodide.The +-cyanines (IX) were prepared eitherfrom 2-iodoquinoline alkyliodide and p-naphthaquinaldine alkyl-has now been further extended.74R' X (VIII.)iodide or from quinaldine alkyliodide and 2 -iodo- p-napht haquinolinealkyliodide by the action of alkali. Analogous thio-$-cyanines were72 W. Kanig, W. Kleist, and J. Gotze, Ber., 1931, 64, [B], 1664; A., 1076.73 See Ann. Reports, 1928, 25, 181 ; 1930,27, 186.7' Miss F. M.Hamer and Miss M. I. Kelly, J., 1931, 777ORGANIC CHEMISTRY .-PART In. 165obtained by a similar process from 2-iodo-p-naphthaquinolinealkyliodide and 1 -met hylbenzt hiazole alkyliodide.Alkaloids.Pyridine Group-An extension of the recent work 75 on thenature of the products from Lobelia inflata has indicated the presenceof several minor alkaloids, of which one-lobinine, C18H2702N-has been the subject of a detailed The interesting con-clusion is reached that this alkaloid may have the structure (I), inwhich there is a 7-membered ring. Its simple reactions clearlydemonstrate its nature as an alcohol, a ketone, and a tertiary amine,and much of the evidence for the size of the ring system is derivedfrom a study of the degradation of the corresponding diketone,Cl8H2,O2N.When the methiodide of the last substance wasp 2 - 7 J 3 2\/QH2 p 2 ;\". COPh*CH,-CH CH*CH,-CHMe.OHQH2 ( p 2COPh*CH,*CH CH*CH,-CHPh*OH NMe(1.) v NMe (11.)treated with aqueous sodium bicarbonate, it gave dimethylamineand an unsaturated diketone, C,,H,O,, which was transformedultimately into the corresponding saturated compound, C17H240,.The latter yielded, on oxidation, benzoic acid and suberic acid,CO,H-[CH,],*CO,H, from which it is concluded that it has theformula COPh*[CH,],*COMe. It is admitted, however, that theseresults could be accounted for on the basis of the structureCOPh.[CH,],*COCH,Me for the saturated diketone, in which caseit would be possible to formulate the alkaloid as a piperidine deriv-ative similar to the better-known members of this group.Never-theless, the 7-membered ring structure is favoured on the groundsthat, unlike the other Lobelia alkaloids, lobinine gave neitherl-methylpiperidine-2 : 6-dicarboxylic acid nor 1 -methyl-2-carboxy-piperidine-6-acetic acid on oxidation. The relative positions ofthe carbonyl and hydroxyl groups are indicated by the fact thatthe alkaloid, like lobeline (11), readily yields acetophenone.Preliminary work on the nature of the bases contained in AnabasisaphgZh has been de~cribed,~' and it is noteworthy that lupinine hasbeen isolated from the lower-boiling fraction. In addition, a newalkaloid, anabasine, believed to be 3-(2'-piperidyl)pyridine (111) has7 5 See Ann. Reports, 1929, 26, 169.76 H.Wieland, M. Iahimasa, and W. Koachara, Annalen, 1931,491, 14.7 7 A. Orechov and G. Menschikov, Ber., 1931,64, [B], 266; A., 498166 PLANT :been obtained. In support of this structure it has been observedthat the compound can be benzoylated and nitrosated. Oxidationwith potassium permanganate gave nicotinic acid, and dehydro-genation resulted in the loss of six atoms of hydrogen and theformation of a product which is apparently 2 : 3’-dipyridyl (IV).The structure (111) has previously been advanced 78 for nicotimine,CH,a minor alkaloid from tobacco, but tlhe latter appears not to beidentical with anabasine.Of considerable interest is the observation 79 that a by-product,C,H,Op,, always accompanies the nicotinic acid obtained by theoxidation of nicotine with nitric acid.The reactions of this com-pound suggest that it is 4-nitro-5-(3’-pyridyl)pyrazole (V), and itsformation clearly involves very remarkable changes in the molecularstructure .isoQuinoZine Group.-A description has appeared *O of the applic-ation to the synthesis of hydrastine (I; R = H) of two routespreviously used for the preparation of the closely related a-gnosco-pine (dZ-narcotine). The condensation of hydrastinine (11) andnitromeconine (111) led, on subsequent reduction, to a mixture ofOMeR e M eCH CO/ \H2C NO,O a O M e (111.)OC OMethe two stereoisomeric, inactive aminohydrastines (I ; R = NH,).After separation of the mixtaure and removal of the amino-groupvia the hydrazino-compounds, the corresponding stereoisomeric7 8 A.Pictet, Amh. Pham., 1906, 244, 388.79 G. A. C. GoughandH. King, J., 1931, 2968.80 E. Hope, F. L. Pyman, F. G. P. Remfry, and R. Robinson, J., 1931,81 E. Hope and R. Robinson, J., 1914,105, 2086.236ORGANIC CHEMISTRY.-PART m. 167dZ-hydrastines were obtained. Similarly, the condensation ofhydrastinine with iodomeconine gave a mixture of the two stereo-isomeric iodohydrastines ( I ; R = I). The exact relationship ofthese inactive forms to the natural Z-hydrastine is not yet clear.Earlier degradative experiments have indicated the main featuresin the constitution of oxyacanthine, and have enabled two formulie,differing only in minor details, to be advanced for theFurther work 83 has now provided confirmation for these structuralviews.The product obtained from oxyacanthine methyl ether bythe Hofmann degradation process gave two well-defined substanceson oxidation with ozone. One of these proved to be 2’-methoxy-diphenyl ether-4 : 5’-dialdehyde (IV) and yielded the correspondingdicarboxylic acid (already known) on further oxidation. The otherwas a base, C,,H,,O,N,, which contained three methoxyl groupsand gave a dimethiodide. The latter salt was easily broken downby alkali to give trimethylamine and a nitrogen-free compound,C,1H,,06, which was found to be a dialdehyde containing twoethylenic linkages. These reactions are satisfactorily explainedwith the aid of formula (V) for the base C25H3406N2, but there isno evidence yet to indicate the exact locations of the methoxylgroups and the ether linkage.Until such information is forth-coming, several alternatives of the type (VI) exist as possibilitiesfor oxyacanthine. It is probable that one of these represents theclosely related alkaloid berbamine.MeN HzY&oMe A OMe Me0 o,egeMe0 (IV.) b o € € (v;dMe2N*CH2*CH, OMe Me0 CH,*CH,*NMe,(V.1 OHCOOMe o&klHOIn last year’s Report 84 itl was mentioned that the formula (VII)had been tentatively suggested 85 for chelidonine ; valuable experi-mental evidence in support of this structure is now forthcoming.86Ann. Reports, 1929, 26, 173.83 F. von Bruchhausen and P. H. Gericke, Arch. Phccm., 1931, 269, 115;84 Ann. Reports, 1930, 2’7, 195.85 F. von Bruchhausen and H. W. Bersch, Ber., 1930,63, [B], 2520.86 E.Spath and F. Kuffner, Ber., 1931,64, [B], 370; A., 500.A., 636168 PLANT :The oxidation of N-acetylanhydrochelidonine 87 with nit,ric acid hasbeen found to yield benzene-1 : 2 : 4-tricarboxylic acid, while theoxidation of chelidonine with potassium permanganate gavehydrastic acid (VIII) and 3 : 4-methylenedioxybenzene-1 : 2-dicarb-oxylic acid. Confirmation of the nature of the fundamental ringsystems in chelidonine and the closely related alkaloid sanguinarineis derived from the fact that the latter substance yields, on zincdust distillation, a base which is now identified as a-naphthaphen-anthridine (IX). The position of the alcoholic hydroxyl group isCH,indicated by the result's obtained from an application of the Hofmannand Emde degradation processes to chelidonine.This structure for chelidonine being accepted, the known factsconcerning sanguinarine and its relationship to the former alkaloidsuggest for it the formula (X).The alkaloids homochelidonine,Cz1H2,0,N, and chelerythrine, C2,H,@,N*OH, are very closelyrelated to chelidonine and sanguinarine respectively, and probablydiffer from them only in having one of the two methylenedioxy-groups replaced by two methoxyl groups. On this assumption aninvestigation has been made 88 of some of the reactions of chel-erythrine chloride in order to determine which methylenedioxy-group is involved. When oxidised with potassium permanganateunder various conditions it yielded the methylimide (XI) of hemi-pinic acid and also hydrastic acid.It was observed, furthermore,that chelerythrine chloride gave a-naphthaphenanthridine (IX) onzinc dust distillation. The indications are, therefore, that homo-87 Derived from chelidonine by acetylation as described by J. Gadamer,8 8 E. Spath and F. Kuffner, Ber., 1931, 64, [B], 1123.Arch. Phamz., 1924, 282, 265ORGANICchelidonine is representedCHEMISTRY.-PART III. 169by the formula (XII) and chelerythrineby (XIII).CH,HO-c/. g>CH, "oO>CH2' H Me0 (&e*OHM e O R c > m e Me0 (XIII.)Me0 CH, (XII.)The assumption regarding the nature of the relationship betweenchelerythrine and sanguinczrine has been shown to be valid byremoving the met hylenedioxy-groups from dihydrochelerythrineand dihydrosanguinarine by treating these products with phloro-glucinol and boiling 50 yo sulphuric acid.The hydroxy-compoundsso obtained, on subsequent methylation, both yielded the samederivative 89 (XIV) .Me0 @ EEoA??H\T/V CH CH, CHCH, CH2/ \ / \H2Y p QHMeOMe M>d CH, \/CH, H&\/(XIV.) CH, (xv.) CH,Reference has been made in a previous Report to the preparationof substances which might, in view of the known facts concerningthe structure of emetine, possess amcebicidal properties. Since it isthought that emetine can be represented by the formula (XV),glthe work has now been extendedg2 to the synthesis of the closelyrelated 10 : ll-dimethoxy-1 : 2 : 3 : 4 : 6 : 7-hexahydrobenzpyrido-(XVI.) (XVII.) (XVIII.)coline (XVI; n = 4).8-chlorovalero- p-veratrylet hylamide,This was accomplished by first convertingCH,Cl*CH,*CH,*CH,*CO*NH*CH,*CH,*C,H,( OMe),,*Q E.Spath and F. Kuffner, Ber., 1931, 64, [B], 3034.QO Arm. Reports, 1929, 26, 172.81 W. H. Brindley and F. L. Pyman, J., 1927, 1067.Q2 R. Child and F. L. Pyman, J., 1931, 36.F 170 PLANT :into 1 - 8- chlorobutyl- 6 : 7 - dimethoxy - 3 : 4 - dihydroisoquinoline(XVII) by the action of phosphorus oxychloride. The latter gavethe salt (XVIII) on warming, and the desired base (XVI; n = 4)was then obtained by reduction. A similar series of reactionsstarting from y-bromobutyro- p-veratrylethylamide led to theanalogous base (XVI; n = 3), but, when these products and someof the intermediates were examined, they were found not to possesspronounced physiological properties.The view has been expressed 93 that trilobine and homotrilobine,alkaloids from species of CoccuZus, belong to the l-benzyltetrahydro-isoquinoline group, but the evidence so far available does not dis-close the complete structures, The isolation of two additionalalkaloids from Cocculus trilobus has also been described.94 One ofthese, trilobamine, is apparently closely related to oxyacanthineand berbamine.Aporphine Group.-It has been demonstrated 95 that three well-defined alkaloids of the aporphine type can be extracted from thebark of LuureZia Novce Zealandice.One of these, pukateine (I),contains a methylenedioxy- and a phenolic hydroxyl group, andthe formula assigned to it is based upon an examination of theproducts derived from an application of the Hofmann method of MeOO\ili,degradation and from various processes of oxidation.The secondalkaloid, laureline (11), contains a methylenedioxy- and a methoxy-group, but is different from pukateine methyl ether.ative reactions support the formula (11).Its degrad-The third, laurepukine,93 H. Kondo and M. Tomita, Chem. Zentr., 1931, i, 1114.94 H. Kondo and M. Tomita, Arch. Pham., 1931, 269, 433.s5 G. Barger and A. Girardet, HeZv. Chim. Acta, 1931, 14, 481, 604; A.,749, 750ORGANIC CHEMISTRY.-PART IlI. 171which is now characterised for the fist time, contains a methylene-dioxy- and two phenolic hydroxyl groups. The evidence for itsstructure is less conclusive than in the two previous cases, but thealkaloid may be represented by the formula (111), or possibly (IV).Confirmation of these structural views from synthetical experimentswill be awaited with interest.Considerable confusion has existed concerning the exact relativepositions of the hydroxyl and methoxyl groups in certain well-known members of the aporphine class, although the locations ofthe oxygen atoms have been definitely established by the synthesisof the fully methylated derivatives. For some time past theformula (V) has been accepted for corytuberine, while the structures(VI) and (VII) respectively represent.the prevailing views 96regarding corydine and isocorydine (the two alternative mono-methylcorytuberines). More recent work,97 however, indicates thenecessity for a further revision of these formula Corytuberinediethyl ether, on oxidation with potassium permanganate, gave4-methoxy-3-ethoxybenzene- 1 : 2-dicarboxylic acid, a result incom-patible with the structure (V).Furthermore, by partial ethylationof corytuberine, a mixture of the two possible monoethyl etherswas obtained, and this, on oxidation with potassium permanganate,gave the two products , 4- met hoxy- 3-et hoxybenzene- 1 : 2 -dicarb-oxylic acid and 5-methoxy-4-ethoxybenzene-1 : 2 : 3-tricarboxylicacid. It thus follows that corytuberine must be represented bythe formula (VIII).HOMe0Me0CH2(VII.1 (VIII.) (IX.)e6 J. Go, Chern. Zentr., 1930, i, 234; Ann. Reports, 1930,27, 196.07 E. Spath and F. Berger, Be?., 1931, 64, [B], 2038172 PLANT :The structures of corydine and isocorydine were revealed in thefollowing way. The methylenedioxy-group was removed frombulbocapnine methyl ether (IX) by treatment with phloroglucinoland sulphuric acid, and the resulting dihydric phenol gave corydineon partial methylation.Corydine must therefore have the struc-ture (X), a fact which is confirmed by the observation that bothcorydine and its ethyl ether give 3 : 4-dimethoxybenzene-1 : 2-di-carboxylic acid on oxidation, and, in view of these results, the onlypossible formula for isocorydine is (VI).AcoThe earlier aporphine syntheses based on the Bischler-Napieralskireaction98 have involved the formation of methyl ethers and sohave thrown no light upon problems of the above type.Theprobability that synthetical methods may ultimately assist insettling some of these difficult points is now foreshadowed by astudy 99 of the possibility of employing in these reactions materialsin which phenolic hydroxyl groups are protected by carbethoxy orbenzyl radicals. So far the experiments have not advanced beyonda preliminary exploratory stage, and further results will be awaitedwith interest.Previous experience has shown 98 that the application of theBischler-Napieralski reaction to the appropriate derivative of theamide (XI) proceeds satisfactorily only when a strongly p-directinggroup in the 3-position promotes the formation of the isoquinolinering. I n other cases the main reaction results in an alternativedehydration process with the production of neutral substances t owhich the structure (XII) has been assigned.A further study ofthe conditions which promote or prevent the formation of anisoquinoline derivative in such cases has recently been made,l andit is clear that the effect of the 2’-nitro-group on the neighbouringmethylene group is such as greatly to assist the alternative process,since it has been found that 4’-methoxyphenylaceto-p-phenylethyl-amide (XIII) readily yields 1 -p-methoxybenzyl-3 : 4-dihydroiso-See Ann. Reports, 1928,25, 185; 1929,26, 174.H. Kondo and S. Ishiwata, Ber., 1931, 64, [B], 1533.99 J. M. Gullsnd and his collabor~tors, J., 1931, 2872, 2881, 2885, 2893ORGANIC CHEMISTRY .-PART III. 173quinoline when treated with phosphorus oxychloride in boilingtoluene.The 2'-nitro-group is, however, necessary for the com-pletion of the aporphine synthesis, and its effect is overcome onlywhen such groups as methoxy and benzyloxy are present in the3-position.MeoQ ( 7 3 2(XIII.)Anotherreaction isco o;,,0-9 (XIV.)interesting application of the Bisc hler-Napieralskiobserved in the facile conversion of numerous acyl-o-xenylamines (XIV) into khe corresponding phenanthridine deriv-atives (XV) by heating with phosphorus oxychloride.2DiisoquinoEine Group.-Further confirmation of the fact thatsinactine, an alkaloid from Sinomenium acutum, must be regardedas Z-tetrahydroepiberberine (I) has been obtained by the resolutionof it synthetical specimen of dZ-tetrahydr~epiberberine.~ Theproperties of the Z-form of the latter base were found to be inagreement with those described for the natural product.OMe O-CH,Some time ago evidence was produced4 to show that nandinine,an alkaloid from Nandina: domesticu, is d-tetrahydroberberrubine(11), but considerable doubt is now cast upon its real nature as theresult of a recent investigation 5 of the purification and resolutionof tetrahydroberberrubine. It is found that the physical constantsof d-tetrahydroberberrubine are in reality quite different from thosegiven for nandinine .Lupin AZ7caZoids.-The past year has been one of great activityin the field of the chemistry of the lupin alkaloids.Some of the2 G. T. Morgan and L. P. Walls, J., 1931,2447.3 E.Spiith and E. Mosettig, Ber., 1931,64, [B], 2048.Z. Kitssato, Acta Phytochh., 1927, 3, 175; Ann. Reprts, 1927, 24, 172.E. Spzith and W. Leithe, Ber., 1930, 63, [B], 3007; A., 242174 PLANT :published statements are polemical in character, so that muchconfusion exists, but, since most of the work has been directedtowards testing recent structural formulze, the results are of con-siderable general interest.Although the homogeneity of lupinine has been doubted duringthe year, it now seems certain that the substance which melts at68-69' is a single compound.6 Interesting results, however, havebeen obtained 7 from the degradation of a less pure specimen(m. p. 63-65') derived from the seeds of the yellow lupin, and itis claimed that these support Karrer's formula (I) for the alkaloid.For instance, lupinane, Cl,HlgN, obtained by the dehydration andsubsequent hydrogenation of the alkaloid, was converted intobromolupinanecyanoamide, CI1Hl9N2Br, on treatment with cyanogenbromide.The lupinanecyanoamide, C,,H,,N,, obtained from thelatter by removal of the bromine, yielded a secondary piperidinebase, CloH,lN, on hydrolysis. Dehydrogenation of the latter withsilver acetate in acetic acid at 180" led to the corresponding tertiarypyridine base, C1,HISN, which was shown by oxidation to be amixture of 3-methyl- and 6-methyl-2-n-butylpyidine. Thus, bythe action of potassium permanganate, the following products wereobtained : 2 -n- butylpyridine- 6 -carboxylic acid, 2 -met hy lpyr idine -6-carboxylic acid, pyridine-2 : 3-dicarboxylic acid, and 3-methyl-pyridine-2-carboxylic acid. These results can be explained withthe aid of Karrer's formula, but require the assumption that thelupinine used contained an isomeride (11), to which the name'' aZZolupinine " has been assigned; the relative amounts of theoxidation products indicated that the base (I) preponderated. It hasbeen more recently stated * that the pyridine derivatives whichsuggest the presence of allolupinine are not obtained from a specimenof lupinine melting at 68-69'.CH, CH*CH,*OH CH, CH,H2+9d\p2 H2CAFH\CH2 (11.)(I.) H,C'\/NvCH, H , q , p y C H 2CH, CH, CH, H*CH,.OHOf considerable importance in connexion with the structure tobe assigned to lupinine is the recent synthesis of octahydropyrido-coline (111). This has been achieved by first condensing ethylpiperidine-2-carboxylate with y-bromobutyronitrile to give theC. Schopf, E. Schmidt, and W. Braun, Ber., 1931, 64, [B], 683; A., 635;P. Karrer, ibid., p. 942; A . , 750. ' K. Winterfeld and F. W-. Holschneider, ibid., p. 137; A,, 370.K. Winterfeld, ibid., p. 692 ; A., 635.G. R. Clemo end G. R. Ramage, J., 1931,437ORGANIC CHEMISTRY.-PART III. 175nitrile (IV). The corresponding dicarboxylic ester, prepared fromthis by the action of alcoholic hydrogen chloride, was submitted tothe Dieckmann react ion, and ethyl 1 - ket o-octahydropyridocoline-2-carboxylate was obDained. l-Keto-octahydropyridocoline, pre-pared from the latter by hydrolysis with dilute sulphuric acid,yielded octahy&opyridocoline when reduced with amalgamatedzinc and concentrated hydrochloric acid.Although the decarboxylation of lupininic acid (V) with soda-lime leads to a complex mixture, there has been isolated from it,after reduction with palladium and hydrogen, a base, CgH,,N,which has the same molecular formula as, but is not identical with,octahydropyridocoline. This result does not of necessity invalidateKarrer’s formula for lupinine, since fundamental changes of structuremay occur during the formation of the new base.The fact that lupanine, C1,H2,0N2, and sparteine, C,5H26N2, arestructurally closely related is made probable by the interestingobservation 10 that d-lupanine can be reduced with hydriodic acidand red phosphorus to a base which appears to be identical withnatural Z-sparteine. In an attempt to establish one of the fouralternative formulze previously advanced by Karrer and his col-laborators for sparteine, the alkaloid has now been degraded toa saturated hydrocarbon, Cl5H,,, by repeated applications of theHofmann process and catalytic hydrogenation of the intermediateproducts.12 On the basis of these four formulze this hydrocarbonmight be one of three isomeric pentadecanes, all of which have beenprepared synthetically, but the physical properties are such as tolead to no really definite conclusions.Interesting alternative views concerning the structures of lupanineand sparteine have been advanced. It has been reported thatlupanine has now been made to yield p-lupinane, C,,H,,N, and anoily product which gives the pyrrole pine-shaving reaction, byheating with fuming hydriodic acid and red phosphorus for fifty10 G. R. Clerno, R. Raper, and C. R. S. Tenniswood, J., 1931, 429.11 See Ann. Reports, 1929, 26, 182.12 P. Kmer, B. Shibita, A. Wettstein, and L. Jacubowicz, Hdv. Chim.Acta, 1930,13, 1292 ; A., 241176 PLANThours at 240". In view of this result and the fact that sparteinecan be degraded to 2-methylpyrrolidine, the formula (VI), or someclosely related alternative such as (VII), may represent 1~panine.l~The sparteine structure is derived by replacing the >CO groupby >CH,. Hydroxylupanine, C,5H,,0,N,, would have the samefundamental structure, differing from lupanine in having a hydroxylgroup in the place of a hydrogen atom. Lupanidine, which hasbeen isolated l4 from the mother-liquors of lupinine and is isomericwith lupanine, may have the structure (VIII) in view of the possiblepresence of allolupinine in crude lupinine. These views must atpresent be regarded as rather speculative. In fact, the soundnessof the experimental work upon which they are partly based hasbeen q~esti0ned.l~ Thus it has been asserted that p-lupinane can-not be obtained from pure lupanine by the action of hydriodic acidand red phosphorus, and that its isolation in the work describedabove may be explained by the presence of lupinine in the sampleH27-p32 CH, CH,H2cvc? H2flH'p32 70 H,C N CH,CH CH \/\/H2C,,NQH2CH, CH,(VI.) (VII.) (VIII. )of lupanine employed. This criticism has, however, been resisted,16and it has been re-affirmed that p-lupinane can be obtained fromlupanine .Cytisine, an alkaloid from the seeds of Cytisus laburnum, mayultimately prove to be closely related to the lupin bases. Althoughcomparatively little evidence is at present available regarding itsconstitution, the few known reactions of the substance are not allsatisfactorily explained by the formuh hitherto put forward, andsome recent structural views l7 are accordingly of interest. Thealternative formulz (IX) and (X) have been suggested partly asthe result of an examination of the products of the exhaustivemethylation of the alkaloid. If these views are sound, the pro-l3 K. Winterfeld and A. Kneuer, Ber., 1931, 64, [B], 150; A., 371.l4 A. Kneuer, Diss., Freiburg i. Br., 1929.l5 G. R. Clemo, Miss G. C. Leitch, and R. Raper, Ber., 1931, 64, [B], 1520.l6 K. Winterfeld, A. Kneuer, and F. W. Holschneider, ibid., p. 2415.l7 H. R. Ing, J., 1931, 2195ORGANIC CHEMISTRY .-PART III. 177duction of 6 : 8-dimethylquinoline, 2-hydroxy-6 : 8-dimethylquhol-ine, and ammonia when cytisine is reduced with hydriodic acid andMe iuMered phosphorus must involve primarily a rupture of the pyrrocolineskeleton, followed by the formation of the quinoline nucleus. Otherreactions of the alkaloid can be accounted for with the aid of theseformulB, but the direct evidence for the pyrrocoline structure is atpresent scanty.Morphine Group.-The production of thebainone (I) during thecomplex transformations of the morphine alkaloids has not hithertobeen observed,18 although some simple derivatives of it have beenisolated. It has now been reported,lg however, that it accom-panies metathebainone (11) in the product of the reduction ofthebaine by means of stannous chloride and concentrated hydro-Me0H0Q\p2 C CHchloric acid, and, under the most favourable conditions, may formthe main constituent. It is also produced during the reduction ofcodeinone under similar conditions. These results have enabledinteresting deductions to be made concerning the complex changeswhich ensue when thebaine is treated with concentrated hydro-chloric acid, but the latter cannot be adequat,ely dealt with in thescope of this Report.Strychnine.-Although much published work dealing withstrychnine and brucine has again appeared during the year, thel8 The “ thebainone ” prepared by Pschorr by reducing thebaine withstannous chloride and concentrated hydrochloric acid is now called “ meta-thebainone ” in accordance with the revised nomenclature of this group (seeAnn. Reports, 1930, 27, 197).1s C. Schopf and H. Hirsch, Anmlen, 1931, 489, 224178 ORGANIC CHEMISTRY.-PUT III.chemistry of this group is so complex that only that which has avery direct bearing on suggested structural formulae can excitewidespread interest, and only those aspects will be surveyed inthis review. I n the development of the recent formula for strych-nine 2o much has depended upon the nature of dinitrostrychol-carboxylic acid. Last year, from the evidence then available, thisacid was regarded 21 as possessing one of the formula (I) and (11).Subsequent investigations 22 have shown, however, that dinitro-strychol can be transformed by the usual Curtius reactions into aurethane, so that it mustCO-Hnow be considered not as a dihydroxy-OHquinoline but as an indolecarboxylic acid, probably of the struc-ture (111). Dinitrostrycholcarboxylic acid, therefore, is 5 : 7-di-nitroindole-2 : 3-dicarboxylic acid (IV). The stability of dinitro-strychol is very surprising and is largely responsible for the failuret o recognise its true nature at an earlier date. The latest strychninet*C02HC*CO,H (Iv')(111.)NO, NH NO, NHformula, containing a quinoline skeleton, now rests on a less solidfoundation, but it is not necessarily definitely excluded by thisrecent development. It is important to observe, however, that thedoubt which has existed regarding the presence of the quinolinesystem in dinitrostrycholcarboxylic acid has been coupled withthe opinion 23 that the strychnine molecule contains a dihydroindoleskeleton, which was a feature of the earlier formula of Fawcett,Perkin, and Robinson.Of some interest is the isolation24 of three new alkaloids fromthe strychnine mother-liquors. These are a-colubrine, C2,H2403N,,the isomeric p-colubrine, and $-strychnine, probably Cz,H2,03N2 orS. G. P. PLANT. C21H2403N2'2o See Ann. Reports, 1928, 25, 193; 1929, 26, 181; 1930, 27, 199.21 K. N. Menon, W. H. Perkin, and R. Robinson, J., 1930, 830.22 K. N. Menon and R. Robinson, J., 1931, 773.p3 H. Leuchs, Ber., 1931, 64, [B], 461.24 K. Warnat, Helv. Ohirn. Acta, 1931,14, 997; A., 1312

ISSN:0365-6217    

DOI:10.1039/AR9312800066

出版商:RSC    

年代:1931

数据来源: RSC

摘要:

ANALYTICAL CHEMISTRY.ONE of the most interesting analytical publications of the year isthe “ Festschrift ” to Wilhelm Bottger contributed by his pupilsand co-workers. This contains an important paper by I. M. Kolthoffembodying a fundamental discussion of the sensitiveness of pre-cipitation reactions,2 which sets out from the rule laid down byBottger many years ago, namely, E = L + S, where E is thesensitiveness, L is the solubility on the Nernst solubility law, and Sis the visibility of the precipitate. This rule held strictly for silverhalides, but failed in other cases, since the expression involved theassumption that L and 8 were constant. Such an assumption couldscarcely hold strictly except in the few cases of Precipitates wherethe solubility and visibility are largely independent of the particlesize and method of precipitation. Now the variation of solubilitywith particle size for a completely dissociated salt of low solubilitymay be derived by means of the expression RT/M .log S,/8 =2o/pr, in which 8,/S is the ratio of the solubility of particles of smallradius r (of the order of<p) to that of the solubility of fair-sizedcrystals, p is the density, and G the surface tension, other lettersbearing their usual meaning. If the value of SJS is calculated forvarious insoluble substances, e.g., barium sulphate or silver chloride,it is found that increases of solubility of altogether different ordersof magnitude are found, quite apart from questions of the crystallineor colloidal character of the precipitates.This consideration goes along way towards explaining the differences found in the quantitativeprecipitation of substances of the same order of solubility. It alsopoints to the necessity for careful specification of the size of theprecipitated particles when “ supersaturation ” is considered inrelation to quantitative precipitation, for the solubility of bariumsulphate, for example, may be nearly 1000 times as great for smallas for large crystals of the order of 2p, whereas that of silver chlorideremains almost constant within a much wider range of particle size.It follows, further, that if the first precipitate of barium sulphatefrom a very dilute sulphate solution is very small, the solution is notsaturated with reference to barium sulphate.On this account, aswell as that of size of Precipitated particle, and departure fromRayleigh’s law of scattering of light, the visibility term S of Bottger’sexpression cannot be regarded its constant even for the same sub-2. anal. Chem., 1931, 86, 1-190. Ibid., p. 34180 FOX AND ELLIS:stance. Now the intensity of light scattered by particles of smalldimensions varies as nv2/A4, where n is the number of scatteringparticles, v the volume of the particles assumed to be of equal size,and A is the wave-length of the scattered light. Where the particlesare less than 0.1 i . ~ the law is valid. If it is applied to a fixed quantityof precipitate, the peculiar result emerges that the brightness of thescattered light may be much less although the number of scatteringparticles is increased enormously.For example, if the particles are0.01 p a t the start, and grow to 0.1 on standing, the intensity of thelight scattered in the first case is far less than that of the second caseof the larger particles, despite the fact that originally there were1000 times as many scattering particles. This considerationemphasises once again the necessity for the strictest regulation of theconditions of precipitation in nephelometric measurements in orderto obtain particles of constant size with which to conduct determin-ations. It also indicates the need for the observer to obtain calibra-tion curves for each substance he is estimating. When nephelo-metric determinations of sols are made, this is still more necesary,since the intensity of the scattered light does not then follow thelaw in all cases.3The desirability of careful reconsideration of each case wherenephelometric methods are to be employed in atomic-weightdeterminations and similarly accurate work is discussed by C.R.Johnson in a series of papers.* It is commonly assumed that theequal opalescence end-point as used by Richards and Wells for thesodium chloride-silver titration is equally applicable in all cases.Now, the nephelometric method is remarkably sensitive, quite smallchanges in the character of the sols causing relatively large variationsin intensity of the scattered light. Hence the assumption that theopalescence end-point will be equally balanced for multivalent asfor univalent ions does not necessarilyapply.In fact, if the vastlydifferent coagulating powers of multivalent and univalent ions aretaken into consideration, it seems more probable that the former ionswill favour unbalanced actions, thus rendering the equal-opalescenceend-point method doubtful until it has been shown definitely toapply to any particular multivalent ion. Johnson therefore sug-gests an alternative end-point, called " standard solution end-point,"the object being to determine the absolute quantities of silver andhalide ions in the liquid under the conditions of the test, rather thanthe relative quantities as is usually the case. It is shown thatshaking and cooling of the supernatant liquid in determining the3 H.Bechold and F. Hebler, Kolloid-Z., 1922, 31, 70.J . Physical Chem., 1931, 35, 540, 830, 2237, 2581; A., 456, 584, 1141,1256ANALYTICAL CHEMISTRY. 181quantity of chloride may result in leaving an excess of halide in thesupernatant liquor, and such a result would have the effect of lower-ing the value for the calculated atomic weight.The magneto-optic method of analysis has been applied to theinvestigation of the isotopes of Au, Pt, Rh, Ru, Ta, and Th,5 butthe search for element 87 by the method indicated that there is apossibility of obtaining values for the time-lags between Faradayeffect and magnetic field, which are the same for different complexions of very nearly equal molecular weights. Thus, complex ionssuch as SnC1,' or ReC1' will have a molecular weight of about thesame magnitude as would be expected for the atomic weight ofelement 87 and would thus appear in the same position wheninvestigated by magneto-op t ic analysis.For some time past, investigations of spectral absorption of highprecision have been carried out in the infra-red region of the spec-trum, mostly by means of apparatus depending upon the effect ofthe infra-red radiation transmitted by gases or liquids, on thermo-piles of great delicacy, combined with galvanometers of highsensitivity.The technique is not easy, but the circumstance thatcertain groups of atoms gave characteristic bands in the infra-redpointed to the possibility of utilising the measurement of these bandsas a means of analysis.It is, for example, now well established thatcompounds with a C-H group always show oscillation bands veryclose to 0.9 p, 1 p, and 3.4 p, a fact which is easily seen when thebands of chloroform and carbon tetrachloride are compared. Theintroduction of '' neocyanine " sensitised photographic platespermits of the photography of the near infra-red up to about 1 p andbeyond with some ease and rapidity, and it therefore becomespossible to utilise glass spectrographs in this region. In this way,it has been found possible to detect 1% of ethyl or butyl alcohol incarbon tetrashloride, for these substances show the characteristicbands of C-H, but also show the -OH oscillation band a t 0-96 p.This band does not disappear until the concentration of the alcoholis lower than 0.1%.6 It is an interesting point, theoretically, toobserve that the 0.96 p band has its maximum at about 20% con-centration of the alcohol and it becomes weaker on dilution.Thispeculiarity is similar to that observed in the Raman effect withnitric acid, which was attributed to electrolytic dissociation, and asimilar explanation is advanced to explain the diminution inintensity of the -OH bands of the alcohol when dissolved in carbontetrachloride.Owing to the comparative ease with which the Raman spectraF. Allison and E. J. Murphy, Physical Rev., 1930, [ii], 36, 1097.R. Freymann, Compt. rend., 1931, 193, 928182 FOX AND ELLIS:may be obtained, it is not surprising that the attempt to bring themethod into use as an analytical procedure is receiving attention.Itis found that a- and p-pinene, carene, and camphene show charac-teristic displacements of the scattered radiation, and that a terpenemixture gives the Raman spectra of all the constituents. Sincethese spectra are readily picked out, the possibility arises of utilisingthe effect quantitatively.7 A further application is in the detectionof isomerides. For instance, ha-hexene in methylethylcycEopropanegives its characteristic Raman line, 1642 cm.-l, so that some 2% ofthe hexene is detectable.8The use of arc and spark spectra in the quantitative determinationof metals in alloys has made important advances in convenience ofapplication and certainty of results. Particularly striking are theresults now obtained by utilising for the photometer the rotatinglogarithmic wedge-sector as applied originally to spectrum analysisby Scheibe and Neuhausser. The rotating sector in this case is ofentirely different character from that usually employed in determin-ing extinction coefficients in absorption spectra.It consists of adisc from which a part of the periphery is cut away in such a mannerthat the circumferential aperture, 0 (expressed as a fraction of onecomplete revolution), measured a t a, distance 1, radially inwards fromthe outermost part of the disc, follows the relation - log 0 =0.3 + 0.2 1. The advantage of this scheme is that small variationsin the arc or sparking voltages, or in the development of the photo-graphic plates, do not throw the results out.This was one of thedefects of the earlier methods employed by Hartley, Pollock, deGramont, and others. From the shape of the sector opening in frontof the spectrograph slit, it follows that the spectrum lines are thinwedges instead of the ordinary parallel-sided lines. The length ofthe wedges varies with the intensity of the lines, this being the effectof cutting the sector to accord with the logarithmic expression givenabove. In order, then, to apply the method in practice to a metal,say nickel in steel, a number of spectra of standard specimens ofnickel steel is photographed, and the difference in the length of thewedge given by some well-known nickel line from that of a neighbour-ing iron line is plotted against the percentage of nickel.It will beseen that, by employing this difference method of " line-pairs," smallvariations in conditions are eliminated since it is known experi-mentally that the differences remain constant. In a typical case,G. Dupont, P. Daure, and J. Allard, Bull. SOC. chim., 1931, [iv], 49, 1401.* R. Lespieau, M. Bourguel, and R. L. Wakernan, Compt. r e d . , 1931, 193,9 F. Twyman and C. S. Hitchen, Proc. Roy. SOC., 1931, [ A ] , 133, 72; A . ,238; A., 1147.1260ANALYT1CA.L CHEMISTRY. 183for example, the arc lines Nil3415 and FeA3418 are employed,permitting reasonably accurate and rapid determinations of nickelin steel to be made up to 5% of the element.10 A further advantageof the wedge-sector method is that it has been successfully employedfor determining metals in their solutions as chlorides.In this case,a special kind of sparking vessel for the solutions was devised,ensuring constant supply of fresh liquid during the time required forphotographing the spectrum, and eliminating rnculties arisingfrom decomposition of the solutions around the electrodes and fromincrustations. For solutions, an ‘‘ internal standard ” is obtainedby adding a known and definite amount of the chloride of somemetal which does not occur as an impurity in the material underexamination, but which gives lines close to those of the metal beingdetermined. It is often possible to choose pairs of lines, one fromthe standard and one from the metal, whose relative intensities arenot affected by varying spark conditions, so-called ‘‘ homologouspairs ” of 1ines.ll The extent t o which spectrum analysis has nowbeen carried is well illustrated by its utilisation for the analysis ofminerals.12 While it is too much to expect that a complete analysisof a mineral can be made in this way, it is undoubtedly the fact thatmany of the metallic elements and some of the non-metals can bedetermined very accurately by spectroscopic methods.Thesensitiveness of the method may be very great indeed. It has beenshown that as little as 1 y of chromium can be detected with a carbonarc, and as small a quantity as 6 x y when dissolved in fuseda1~mina.l~ Again, as little as 0.5 part per million of aluminium canbe estimated approximately in the ashes from biological material,14using pure copper electrodes for production of the arcs.A com-prehensive investigation on the determination of certain elementssuch as titanium in aluminium by utilisation of “ homologous pairsof lines ” is now available, with details of the manner in which thisprocedure may be utilised practically.15Attention is directed to a development in the methods of determin-ing halogens, including fluoride, in organic compounds. There arefew convenient and rapid methods for this purpose, especially incompounds containing high proportions of halogens. The processemploying sodium and absolute alcohol fails in many cases, givinglow results, and the method of oxidation by hot sulphuric acid andlo F. Twyman and A. A. Fitch, J .Iron Steel Inst., 1930, ii, 289.l1 E. Schweitzer, 2. anorg. Chem., 1927, 164, 127.l2 See F. Lgwe, Fortschr. Min., 1927, 12, 220.J. Papish and W. J. O’Leary, I d . Eng. Chem. (AnaE.), 1931, 3, 11 ; A.,455.l4 D. Tourtelotte and 0. S. Rask, ibid., p. 97; A., 662.l5 A. Schleicher and J. Clermont, 2. anal. Chern., 1931, 86, 191, 271184 FOX AND ELLIS:an oxidising agent also has limitations and requires special apparatusfor successful operation. E. Chablay l6 first utilised the action ofsodium dissolved in liquid ammonia for determining halogens inorganic compounds, and this was followed by F. B. Dains and his co-workers l7 and by C. w. Clifford.18 The process has been re-examinedand simplified so that it is available as an ordinary laboratorymethod.I n some cases, where two halogen atoms are attached to thesame carbon atom, cyanide is formed, but this is eliminated in theprocess described by T. H. Vaughn and J. A. Nie~w1and.l~ Toavoid the delay in decomposition resulting from insolubility of theorganic compound in liquid ammonia, an organic liquid unacted onby sodium in ammonia is added, e.g., dimethylacetal or ether. Thereaction is then complete in a few minutes, and ammonium nitrateis added to the liquid ammonia before this is allowed to evaporateand the excess of sodium destroyed. The halogen is determined inthe sodium halide by the usual methods, and the process is statedto be suitable for micro-determinations. An important advantageof this method is that it can be used to decompose organic fluorinecompounds containing other halogens as well.Some definite advances are announced in the practical develop-ment of the use of thermionic valves as accessories for determiningpH values and in potentiometric titrations of all kinds.Especiallyimportant is the use of non-aqueous solvents as applied to thedetermination of the acidity of organic substances such as oils. Oneof the earlier suggestions was to use amyl or (later) butyl alcoholsaturated with lithium chloride and containing quinhydrone.20At first, the alcoholic solution of lithium chloride was used both as areference half-cell and for dissolving the oil, but later a silver-silverchloride half-cell was found to answer. Since a saturated solutionof lithium chloride in butyl alcohol is not a good solvent for oils orresins, a more convenient method was devised by B.L. Clarke,L. A. Wooten, and K. G. Compton.21 I n this case the problem isto overcome the difficulty arising from butyl-alcoholic solutions ofhigh specific resistance. The principle adopted for measuring thetitration is to arrange the circuit so that any change in the potentialof the indicator electrode causes a large deflexion of some indicatingmeter, and this is secured by using vacuum tubes which have highgrid insulation. The procedure is to dissolve the oil in dry butylalcohol containing a little quinhydrone, and add about one-tenth ofAnn. Chim., 1914, [ix], 1, 510.Ibid., 1919, 41, 1051.l7 J . Amer. Chem. SOC., 1918, 40, 936; 1920, 42, 1573.19 I d .Eng. Chem. (Anal.), 1931, 3, 274; A., 1393.2O H. Seltz and L. Silverman, ibid., 1930, 2, 1 ; B., 1930, 248.z1 Ibid., 1931, 3, 321ANALY!CICAL CHEMISTRY. 185the volume of saturated lithium chloride-butyl alcohol mixture.The liquid is kept free from air in a flask filled with nitrogen, and theindicator electrode is bright platinum wire immersed in the liquid,the reference electrode being a calomel half-cell with an agar-agarsalt bridge. A curve is plotted for the titration, giving micro-ammeter deflexions against volume of reagent used. Very sharpmaxima of the curves are readily obtained at the end-point.The problem of potentiometric titrations in cases where readilyreducible substances are present and the hydrogen electrode is inapplic-able is one that arises from time to time in practice. Tungsten elec-trodes seemed to, present possibilities and were found to be usefulin certain solutions;22 they would appear to offer scope for moreextended application.A useful electrode is the antimony-antimon-ous oxide electrode, for it has been shown to be available for suchdifficult titrations as hydrocyanic, sulphurous, selenious, and telluricacids with a, very fair degree of accuracy.23Despite its convenience, the glass electrode has not received theextended use it deserves in determinations of pH values, although i tcan be used for measurements up to p= 9.5 or thereabouts. Part ofthis is doubtless due to the very high resistance of the glass bulbsused, but this need not be serious if the special glass now availableis used, for the resistance may be reduced to a few megohms, therebypermitting the convenient utilisation of the valve electrometer.Animportant scheme is given in detail by C. Morton 24 for the determin-ation of glass-electrode potentials by a ballistic method which getsrid of a troublesome feature, namely, the " creeping " of the zero ofthe galvanometers. This has been accomplished by the introductioninto the anode circuit of a high resistance, across which is thegalvanometer in series with a large capacity of 4 pF or so. We havefound this scheme quite satisfactory in use, especially where obser-vations have to be continued over long periods.There is not much information available on p , values at com-paratively high temperatures, despite the necessity for having suchdata when determinations have to be made in conditions wherecooling is inadvisable. The scheme laid down by S.Stone 25 istherefore of importance. It describes suitable forms of electrodevessels and electrodes. The silver-silver chloride reference electrodeis used in conjunction with a platinum-hydrogen electrode, and p Rvalues for buffer mixtures up to 10 and above 100" are recorded.The change in pH may be positive or negative and is nearly constantin most mixtures for a considerable range of p H .22 H. T. S . Britton and E. N. Dodd, J., 1931, 829; A., 699.23 H. T. S . Britton and R. A. Robinson, ibid., p. 458; A., 585.24 Ibid., p. 2977. 25 Rec. trau. chim., 1930, 49, 1133; A., 184186 FOX AND ELLIS:There is little doubt that, wherever possible, actual determinationof the pH by a potentiometric method is on the whole more satis-factory than colorimetric methods, which are, however, goodenough for much practical work when it is sufficient to know thep , within about & 0.1 unit.Numerous factors influence theaccuracy of the colorimetric tests, &ch as salt effects, proteineffects, and particular errors due to the indicators themselves.Wide-range indicators have to be used with care and may lead toerroneous results in unbuffered solutions such as extracts obtainedin paper testing, from soils, sugar liquors, and so on. Theseindicators are safe with well-buffered liquids or in those cases wherethe p H of the indicator is near that of the liquid under test.It isusually better to use a number of short-range indicators wheneverthe solution is suspected to be unbuffered.26 A further considerationin the preparation of the indicators is that considerable variationsin colour may occur in several ways, especially from the method ofpreparing the indicator, its storage, andIt must always be remembered in the use of coloured indicatorsfor determining pH, that salts may have a definite effect on thecolour of an indicator, and that this varies with the concentrationof the latter. This effect has been measured and even applied todetermine the dissociation of acetic acid.28 The salt error may withsome indicators be serious enough in certain alkaline buffers them-selves, e.g., glycine buffers, to show large discrepancies betweenthe p , values of sodium hydroxide solutions and those of thestandard buffer which gives the same colour with the indicator.29These considerations emphasise the necessity for considering care-fully the choice of indicator in relation to the liquid under examin-ation.For turbid liquids there are the so-called “achromaticindicators,” which are mixtures of indicators so chosen that themiddle point of the colour change in one is complementary to thatof the other, the resulting transition point of the mixed indicatorbeing grey.3o As an example, a mixture of bromocresol-green,neutral-red, and phenolphthalein indicates sharply at pE 4-5 and 8.5,and is therefore available for the titration of phosphoric acid.An interesting method of identifying a solid when the meltingpoint cannot be used because of decomposition, depends upondetermining the b.p. of the saturated solution in a suitable apparatus.If the solid under test is the same as the solute, then the b. p. of the26 F. R. McCrumb, I n d . Eng. Chem. (Anal.), 1931, 3, 233; A., 1023.27 M. G. Mellon and G . W. Ferner, J . Physical Chem., 1931, 35, 1025.28 N. V. Sidgwick and L. A. Woodward, Proc. Roy. Xoc., 1930, [ A ] , 130, 1.20 J. W. McBain, (Miss) M. E. Laing, and 0. E. Clark, J. Gen. Physiol.,30 E. L. Smith, Quart. J . Pharm., 1930, 499; A., 184.1929, 12, 695ANALYTICAL CHEMISTRY. 187saturated solution will not be affected on addition of the unknownsubstance.With due precautions the procedure is available likewisefor ascertaining the purity of a s~bstance.~~A problem which is sometimes of considerable importance inanalysis is the determination of the density of solids when smallquantities only are available. Heavy liquids of suitable range arenot always available for the denser materials. A device is describedwhich gives satisfactory results with as little as 0.05 g. of solid,whether in the form of powder or massive.32 This consists of aglass tube fitted with a capillary side arm on which there are twomarks. The quantity of some suitable liquid, weighed from a weightburette, required to occupy the space between the two marks isascertained. A determination can then be made readily, by fillingthe tube as far as the lower mark with the liquid, introducing aweighed portion of the solid, and then introducing sufficient Iiquidto fill the instrument to the second mark from the weight burette.It is obvious that the weight of liquid displaced by the solid can befound with some accuracy provided precautions be taken to reducevaporisation when volatile liquids are used.The discovery that per-rhenates of certain organic bases, e.g.," nitron," give insoluble compounds is of much value for determiningthe element.Rhenium sulphide may be precipitated from a hotsolution of a rhenium salt acidified with hydrochloric acid. Theprecipitation is rather slow, but the insoluble sulphide is easilyconverted into per-rhenate by suspending it in sodium hydroxidesolution and adding hydrogen peroxide.From an acetic acidsolution the rhenium can be obtained quantitatively as nitron~er-rhenate.~~ The sulphide reaction is delicate, and the precipit-ation with nitron is nearly complete, particularly if nitron acetate ispresent.34 A difficulty arises from the co-precipitation by nitronof any molybdenum present in the solution. Fortunately, molyb-denum can be removed as Mo02(C9H60N), by the use of 8-hydroxy-quinoline in acetic acid solution, leaving the rhenium in solution.35The separation of the bulk of the molybdenum may be effected bydistillation of rhenium chloride a t 175-20O0 from a sulphuric acidsolution of the per-rhenate. The precipitation of the remainingmolybdenum by hydroxyquiiioline can then be carried 0 ~ t .~ 5 ~ Analternative method of estimating rhenium takes advantage of the31 J. 0. Halford, J . Amer. Chem. Xoc., 1931, 53, 2640; A., 1022.32 E. W. Blank, Ind. Eng. Chem. (Anal.), 1931, 3, 9 ; A., 456.33 W. Geilmann and F. Weibke, 2. anorg. Chem., 1931,195, 289; A., 328.34 W. Geilmann and A. Voigt, ibid., 1930, 193, 311 ; A., 1930, 1547.55 W. Geilmann and F. Weibke, ibid., 1931, 199, 347; A., 1143.S5a Idem, ibicE., p. 120; A., 1025188 FOX AND ELLIS:insolubility of thallous per-rhenate 35h from a solution acidified withacetic acid. The thallous per-rhenate is weighed after being drieda t 140", but the results are somewhat low, most likely owing tovolatilisation.Inorganic Analysis.Qualitative.-The sensitivity of certain tests is increased byshaking the aqueous solution with an immiscible and byobservation under strong ill~mination.~~ Schemes are proposedfor the systematic detection of the commoner k a t i ~ n s , ~ ~ and certainanions,39 using 0.1-g.samples. A detailed summary has been madeof the application of organic reagents to mineral qualitative analysis ;40the sensitivity of such reagents generally increases with their mole-cular weight.41 Notes are given for the detection of traces ofchromate in presence of permanganate, of hydrogen sulphide inwater,42 and of nickel in cobalt salts,43 and further observations aremade on the detection of certain heavy metals with diphenylthio-~arbazide.~~ Quinoline 45 and hexamethylenetetramine, ammonia,and h y d r a ~ i n e , ~ ~ have been applied as microchemical reagents ;certain metals afford colour reactions with ammonia in presenceof resorcin01,~7 and the properties of hydroxylamine as a precipitanthave been e~amined.~SAmmoniacal picric acid gives characteristic crystalline precipitateswith copper and some other heavy metals; 49 2 : 7-diaminofluorenecan serve as reagent for copper, zinc, and ~adrnium,~O and " direct-35b F.Krauss and H. Steinfeld, 2. anorg. Chem., 1931, 197, 52; A., 589.36 I. Stone, Ind. Eng. Chem. (Anal.), 1931, 3, 325; A . , 1022; see also Feigl37 W. Bottger and B. M. Schall, ibid., Emich Festschr., 1930, 29 ; A., 1930,3 8 A. Scheinkmann, 2. anal. Chem., 1931,83, 176; 85, 344; A., 587, 1260;39 Idem, ibid.; S. I. Dijatschkovski and T. I. Isaenko, J . Gen. Chem. Russia,40 B. Tougarinoff, Ann. SOC. Sci. Bruxelles, 1930, 50, [B], 145; A . , 188.4 1 V. V. Tamchyna, Mikrochem., 1931, 9, 229; A., 701.42 F. Feigl, ibid., Emich Festschr., 1930, 125; A., 1930, 1547.43 Idem, ibid.; F. Feigl and H. J. Kapulitzas, 2. anal. Chem., 1930, 82,44 H. Fischer, Mikrochem., 1930, 8, 319; A., 328.45 I. M. Korenman, Pharm. Zentr., 1930, 71, 769; A., 1931, 188.46 P. Rby and P. B. Sarkar, Mikrochem., Emich Festschr., 1930, 243; A . ,47 L. Bey, Bull. SOC. chim., 1930, [iv], 47, 1192; A., 1930, 1545.48 J. C. Roldhn, Anal. Fds. Quim., 1930, 28, 1080; A . , 1930, 1547.49 I. M. Korenman, Pharm. Zentr., 1931, 72, 225 ; A., 701 : J . Chem. Ind.Russia, 1931, 8, 276; A., 927.50 J.Schmidt and W. Hinderer, Ber., 1931, 64, [B], 1793; A., 1045.and others, Mikrochem., 1931, 9, 165; A., 590.1545.C. J. van Nieuwenberg, Mikrochem., 1931, 9, 199; A., 698.1931, 1, 81 ; A., 925.417; A., 455.1930, 1544ANALYTICAL CHEMISTRY. 189green B ” for c0pper.5~ Boiling potassium cyanide solution dis-solves zinc, but not cadmium cyanide; 52 methods are describedfor the detection of zinc and silver,54 bismuth,55 andcadmium. 56The elements of the aluminium group are separated from thoseof the iron group by boiling the nitric acid solution with sodiumcarbonate, hydroxide, and peroxide; 57 2 : 2‘-dipyridyl in slightlyacid solution is a sensitive test for ferrous salts, with which it givesa red coloration.58 Reactions of simple and complex iron com-pounds have been investigated.59 The detection’ of chromium 6oand of manganese 61 in minerals and rocks is described, as alsoa number of methods for cobalt, as czesium cobaltinitrite,62 withsodium thi~sulphate,~~ with thi~glycollanilide,~~ and with eriochromeblue-black B and red B.65pNitrobenzeneazoresorcino1, besides being a specific reagent formagnesium,66 is a useful indicator over the range p H 10.8-13.0;a number of other dyes has been investigated, but in all cases cobaltand nickel give the same reactions as magne~ium.~’ For themicrochemical detection of sodium, a uranyl acetate solution isused; 68 modifications of the triple acetate test have been made.69Molybdic acid gives a violet coloration with potassium cetyl-51 P.Sisley and David, Bull. Soc. chim., 1930, [iv], 47, 1188; A., 1930,52 N. A. Tananaev and N. S. Fedulov, Ukraine Chew. J., 1930, 5, (Sci.),53 K. M. Filimonovitsch, ibid., p. 383; A., 927; A. Sergeev, ibid., p. 227;54 A. Sergeev, loc. cit.55 G. Lochmann, 2. anal. Chem., 1931, 85, 841; A., 1262.56 J. S. Pierce and W. T. Forsee, I d . Eng. Chem. (Anal.), 1931, 3, 188;b7 S. Ato, Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1930, 14, 287;5 8 F. Feigl and H. Hamburg, 2. anal. Chem., 1931, 86, 7 ; A., 1261.59 0. Baudisch, Biochem. Z . , 1931, 232, 35; A., 589.H. Leitmeier and F. Feigl, Tsch. Min. Petr. Mitt., 1931, 41, 95; A., 455.61 H. Leitmeier, ibid., p. 87; A., 454.62 H. Yagoda and H. M. Partridge, J . Amer. Chem. SOC., 1930, 52, 4857;63 M.G. de Celis, Anal. Pis. Quim., 1931, 29, 262; A., 814.64 T. Bersin, 2. anal. Chem., 1931, 85, 428’; A . , 1262.6 5 E. Eegriwe, ibid., 1930, 82, 150; A , , 1930, 1547.66 J. V. Dubskj. and A. Ok”, Chem. Listy, 1930, 24, 492; A., 327; I.B7 I. M. Kolthoff, Milcrochem., Emich Festschr., 1930, 180; A., 1930, 1544.68 A. Martini, ibid., 1931, 9, 422; A., 926.P. Feldstein and A. M. Ward, Analyst, 1931, 56, 245; A., 587; R.Montequi and R. de SBdaba, Anal. Pis. Quim., 1931, 29, 255; A., 812.1546.213; A . , 327.A., 327.A,, 701.A., 454.A., 329.Stone, Science, 1930, 72, 322; A., 56190 FOX AND ELLIS:xanthate; 70 delicate tests €or zirconium 71 and germanium 72 aredescribed, as also observations on Feigl's rhodanine reagent forsilver, which gives colorations with gold and palladium.73Limits are given for the sensitivity of the colour reaction of freehalogens with p-aminodimethylaniline. 74 A drop test for thedetection of bromides depends on the formation of eosin fromfluorescein ; 75 preferential precipitation of silver chloride is utilisedfor detecting chlorides in presence of bromide. 76 Chlorates producean opalescence when shaken with saturated aqueous hydrogensulphide, whereas perchlorates and nitrates do not .77 Additionof a solution of benzidine acetate to one of a fluoride in presenceof mercuric acetate affords, under certain conditions, a yellowprecipitate. 78or inpresence of thiocyanate 80 is described. Capillary tubes are recom-mended for storing reagents such as diphenylamine which areunstable in solution ; the 2 : 4-diamino-6-hydroxypyrimidine re-action may be applied to the microdetection of nitrite.81 Thereaction of nitric acid with diphenylbenzidine follows a coursesimilar to that with diphenylamine, but the colour is about twiceits intense and much more affected by excess of reagent.82 Areaction with an acid-alcoholic solution of vanillin occurs withhydrogen peroxide or perborates.83&uccntitative.-Tartrazine and phenosafranine are shown to besuitable adsorption indicators for the mutual titration of chlorideor bromide with silver nitrate.S* Several papers deal with electro-70 J. V. Tamchyna, Chem. Listy, 1930, 24, 465; A . , 329.7 1 F. Pavelka, Mikrochem., 1930, 8, 345; A., 329 ; F.Feigl, P. Krumholz,72 W. Geilmann and K. Briinger, 2. anorg. Chem., 1931, 196, 312 ; A . , 455.73 F. Feigl and H. Leitmeier, Tsch. Min. Petr. Mitt., 1931, 41, 188; A.,701; F. Feigl, P. Krumholz, and E. Rajmann, Mikrochem., 1931, 9, 165;d., 590.A drop method for detecting ferrocyanide when aloneand E. Rajmann, ibid., 1931, 9, 395; A., 928.74 H. E. Tremain, Ind. Eng. Chem. (Anal.), 1931, 3, 225; A., 699.7 5 A. V. Pavlinova, Ukraine Chem. J., 1930, 5, (Sci.), 231; A . , 325.7 6 G. G. Longinescu and T. I. Pirtea, Bull. Acad. Sci. Roumaine, 1930, 13,7 7 T. P. Raikova-Kovatscheva, 2. anal. Chem., 1930, 82, 415; A . , 451.7 8 C . Pertusi, Atti I I I Cong. Naz. Chim., 1929, 573; A . , 925.'9 A. V. Pavlinova and T. N.'Bach, Ukraine Chem.J., 1930, 5, (Sci.), 235;80 Idem, ibid., p. 233; A., 326.81 F. L. Hahn, Mikrochem., Emich Festschr., 1930, 143; A., 1930,a2 H. Riehm, 2. anal. Chem., 1930, 81, 439; A., 1930, 1542.83 C. Griebel, Mikrochem., 1931, 9, 313; A., 925.84 A. J. Berry and P. T. Durrant, Analyst, 1930, 55, 613; A . , 56.195; A . , 185.A . , 326.1542AXALY!Mc)AL CHEMISTRY. 191metric methods for ascertaining p3H85 and with oxidation-reductionindicators.86 Sixteen dyes of different colours have been selectedas suitable internal indicators in volumetric bromate reactions. 87The manner in which the chlorine ion contaminates a numberof precipitates shows that three types of precipitation process maybe recognised. 88 Despite criticism,sg J. Dick upholds his methodfor the rapid drying of precipitates and extends it to a numberof 0thers.~1 A white rod and much indicator are used €or thetitration of dark-coloured liquids.92 The technique of accuratevolumetric analysis as applied to delicate w0rk,~3 the sources oferror in micro-acidimetric tit ration^,^^ the factors affecting deter-minations with the centrif~ge,~5 and the analytical sigdcance ofageing phenomena 96 are discussed.The benzidine reaction for " active " iron may also be used inalcoholic solution and is most sensitive at p , 3.95.97 The presenceof more than 5% of iron prevents the removal of phosphate byboiling with a nitric acid solution of stannous 11itrate.~8Errors in the determination of water by drying are discussed; 99other methods involve decomposition of a-naphthyloxychloro-85 R.J. Fosbinder, J. Lab. Clin. Ned., 1931, 16, 411; A., 811 ; I. M.Kolthoff and T. Kameda, J. Amer. Chem. SOC., 1931, 53, 821; A . , 585;H. T . S. Britton and R. A. Robinson, J., 1931, 458; A., 585; P. Vignon,J. SOC. Leather Trades' Chm., 1931, 15, 367; A., 1141; V. Morani, Ann.Chim. Appl., 1931, 21, 83; A., 450; S. 0. Rawling and G. B. Harrison,Phot. J., 1931, 71, 108; A., 450; M. Kilpatrick, jun., and E. F. Chase, J.Arner. Chem. Soc., 1931, 53, 1732; A., 811; S. Stone, Rec. trav. chim., 1930,49, 1133; A . , 184; B. Elema, (:hem. Weekblad, 1931, 28, 223, 234; A., 699;H. T . S. Britton and E. N. Dodd, J., 1931, 829; A., 699.88 I. M. Kolthoff and L. A. Sarver, J. Amer. Chem. SOC., 1930, 52, 4179;A., 54; J.Knop, 2. anal. Chem., 1931, 85, 253; A., 1256; L. Michaelis, J.Biol. Chem., 1931, 91, 369; A., 687.G. F. Smith and H. H. Bliss, J. Amer. Chem. SOC., 1931, 53, 2091; A . ,925.88 2. Karaoglanov and B. Sagortschev, 2. anorg. Chem., 1931, 198, 352;A . , 926.68 L. Moser and L. von Zombory, 2. anal. Chem., 1930, 81, 95; A., 1930,1149.O0 Ibid., 1931, 83, 105; A , , 584.91 Idem, ibid., 1930, 82, 401 ; A., 453.E. Rossmann, Chem.-Ztg., 1931, 55, 403; A., 810.O3 W. Ponndorf, 2. anal. Chem., 1931, 84, 289; 85, 1 ; A . , 1022, 1259.O4 J. Mika, Mikrochem., 1931, 9, 143; A., 584; 2. anal. Chem., 1931, 86,O 5 K. S. Greene, J. Amer. Chem. SOC., 1931, 53, 3275; A., 1256.O 6 H. Fischer, 2. angew. Chern., 1930, 43, 919; A., 1930, 1541.O 7 A. Simon and T. Reetz, 2.anorg. Chem., 1930, 194, 89; A., 57.s9 M. Dolch and K. Buche, PJlanzenbau, 1930, 4, 6 4 ; A., 1023.54; A., 1256.A. Kriiger, 2. anal. Chem., 1930, 82, 62; A., 67192 FOX AND ELLIS :phosphine,l distillation with chlorinated hydrocarbonsY2 and ebul-lioscopic procedure with methyl alcohol or a ~ e t o n e . ~ Formuhare derived for calculating the state of combination of the con-stituents in mineral waters based on the dissociation constants ofthe acid radicals present and the pH of the water; * methods aregiven for the determination of fluorine, cEsium and rubidium,6and arsenic, molybdenum, and bismuthArsenite solutions are best prepared by dissolving arseniousoxide in carbonate-free sodium bicarbonate solution. Sulphatesof such aromatic amines as aniline and toluidine serve satisfactorilyas standards in alkalimetry ; perchloric acid is similarly applied.loStandardisation of thiosulphate solution by means of ceric sulphateis described.llMicrochemical methods are applied to the determination oftraces of various metals, of hydrogen and carbon monoxide iniron, and of metallic carbonyls in air; l2 the determinations andseparations of the metals of the hydrogen sulphide group have beencritically studied,13 as has also the separation of lead from barium,strontium, and calcium sulphate with ammonium acetate.14 Con-ditions are given for the quantitative separation of lead as chromatefrom iron,l5 bismuth,16 mercury and copper ; l7 precipitation as1 E.Dittler and H.Hueber, 2. anorg. Chem., 1931, 195, 41; A., 325;ibid., 199, 17; A . , 1023; J. Lindner, 2. anal. Chem., 1931, 86, 141; A . , 1257.2 T. R. Fairbrother and R. J. Wood, Ind. Chem., 1930, 6, 442; A . , 185;H. Lundin, Chem.-Ztg., 1931, 55, 762; A., 1256; G. Middleton, Phurm. J.,1931, 12'7, 86; A., 1023.in mineral waters.S. Bakowski, Rocz. Chem., 1931,11, 49, 269, 490; A . , 585, 811, 1023.4 L. Fresenius and 0. Fuchs, 2. anal. Chem., 1930, 82, 226; A . , 1930,5 J. Casares and R. Casares, Anal. Pis. Quim., 1930, 28, 1159; A., 55.6 L. Fresenius, 2. anal. Chem., 1931, 86, 182; A., 1256.8 I. Tananaev, Ukraine Chem. J., 1930, 5, (Sci.), 217; A . , 326.1541.0. Steiner, ibid., 1930, 81, 389; A . , 1930, 1541.E. Strasser, 2. anal. Chem., 1930, 82, 114; A ., 1930, 1541.450 ; see also G. F. Smith and 0. E. Goehler, ibid., p. 61 ; A., 451.1283; A . , 700.1930, 107; A . , 1930, 1546.10 G. F. Smith and W. W. Koch, Ind. Eng. Chem. (Anal.), 1931,3,52; A.,11 N. H. Furman and J. H. Wallace, jun., J. Amer. Chem. SOC., 1931, 53,12 R. Lucas, F. Grassner, and E. Neukirch, Mikrochem., Emich Festschr.,13 P. Wenger and C. Cimerman, Helv. Chim. Acta, 1931, 14, 718; A . , 1261.14 I. Majdel, Arhiv Hemiju, 1930, 4, 76; A . , 1930, 1544; 2. anal. Chem.,1931, 83, 36; A., 453; F. Feigl and L. Weidenfeld, ibid., 84, 220; A . , 926;W. W. Scott and S. M. Alldredge, Ind. Eng. Chem. (Anal.), 1931, 3, 32; A.,453.1 5 H. Funk and 0. von Zur-Muhlen, 2. anal. Chem., 1931,85,435; A., 1260.16 H. Funk and J. Weinzierl, ibid., 1930, 81, 380; A., 1930, 1545.3 7 H.Funk and J. Schormiiller, ibid., 82, 361; A., 187ANALYTICAL CHEMISTRY. 193chromate from dilute perchloric acid is recommended.18 Neutralsolutions of lead salts may be titrated with molybdate l9 or sodiumThe oxychloride is preferred for the separation ofbismuth from lead; 21 lead and bismuth may be titrated by thefiltration method 22 previously used for calcium, magnesium, e t ~ . ~ ~Cadmium may be determined gravimetrically or volumetricallyby means of ammonium m0lybdate.~4 Further observations havebeen made on the use of salicylaldoxime as a reagent for copper ; 25its place may be taken, though without advantage, by variousstructurally-related compounds.26 Separation of copper fromcadmium may be effected with gallic acid 27 or potassium formate,2sand from zinc with iodide and thio~ulphate.~~ Among volumetricmethods for copper, the iodide 3O and one involving permanganateoxidation following precipitation by Spacu’s reaction have receivedattentioa31 Copper and titanium are precipitated from slightlyacid solution by 5 : 7-dibromo-8-hydro~yquinoline.~~The precipitated mercuric sulphide obtained directly from acidsolution is excessive; 33 a method is evolved, particularly fororganic compounds, involving distillation as mercuric chloride ina stream of gaseous hydrogen ch1oride.a Volumetric methods aredescribed for mercuric cyanide 35 and mercurous chloride,36 andD.J. Brown, J. A. Moss, and J. B. Williams, Id. Eng. Chem. (Anal.),1931, 3, 134; A., 701.l@ R.C. Wiley, P. M. Ambrose, and A. D. Bowers, ibid., 1930, 2, 415; A , ,1930, 1545.2o S. Komaretzky, 2 . anal. Chem., 1931, 84, 407; A., 1024; E. Beneschand E. Erdheim, Przemys-t Chern., 1931,15, 153; A . , 701.21 W. Hertel, Metall u. Erz, 1930, 27, 557; A . , 588.22 H. T. Bucherer and F. W. Meier, 2. anal. Chem., 1931,83, 351 ; A . , 588.23 Idem, ibid., 1930,82, 1 ; B., 1930, 1153.24 R. C. Wiley, Ind. Eng. Chem. (Anal.), 1931, 3, 14; A., 453.25 0. L. Brady, J., 1931, 106; F. Ephraim, Ber., 1931, 64, [B], 1215; A.,26 F. Ephraim, Ber., 1931, 64, [:B], 1210; A., 813.27 P. N. Das-Gupta and H. Saha, J . Indian Chem. SOC., 1931,8,19; A . , 813.28 E. I. Fulmer, Ind. Eng. Chem. (Anal.), 1931, 3, 257; A., 1025.2s H. Brintzinger, 2.anal. Chem., 1931, 86, 167; A., 1260.R. Intonti, Ann. Chim. Appl., 1930, 2Q, 583; A., 187; B. Park, Ind.31 J. Golse, Bull. SOC. chim., 1931, [iv], 49, 84; A., 454: L. Cuny, J . Pharm.32 R. Berg and H. Kiistenmacher, Mikrochem., Emich Festschr., 1930, 26 ;33 E. P. Fenimore and E. C . Wagner, J . Amer. Chem. SOC., 1931,53,2453;34 Idem, ibid., p. 2461; A , , 1025.35 E. Cattelain, J . Pharm. Chim., 1930, [viii], 12, 529; A., 187.36 D. Koszegi, Pharm. Ztg., 1931, 76, 524; A., 813.813 : W. Reif, Mikrochem., 1931, 9, 424; A., 927.Eng. Chem. (Anal.), 1931, 3, 77; A . , 454.Chim., 1931, [viii], 13, 513; A., 813.A . , 1930, 1546.A., 1025.REP.-VOL. XXVm. 194 FOX AND ELLIS :Deniges’s cyanide method has been modified.37 The importanceof determining minute traces of mercury is again emphasi~ed.~~Bismuth, aluminium, and zinc, precipitated by S-hydroxy-quinoline are determined colorimetrically with a phosphotungsto-molybdate reagent ; 39 a method has been devised €or determiningsmall quantities of bismuth in organs without decomposing them.40Reduction of stannic salts by lead41 and of antimony also byhypophosphorous acid 42 prior to titration have been examined,particularly as regards the interfering effects of other metals ;reduction with iron powder for small amounts of tin is preferred toaluminium.43 Some notes on the Gutzeit arsenic test are recorded ; 44conditions are given for the use of iodide catalyst in the titrationof arsenious acid and ~ermanganate.~~Diphenylaminesulphonic acid is recommended as indicator forthe titration of iron, especially as tungstate does not interfere,46despite its larger correction.47 Further data are recorded on thepractical applications of Knop’s original method ; 48 p-phenetidinehas also been used as the indicator,49 and on the micro-scale, varioustriphenylmethane dyes.50 The oxidation of ferrous iron by iodinein presence of phosphate proceeds slowly to ~ompletion.~~ Ironmay be separated from manganese by hydrazine hydrate,52 fromcobalt by various mercury-ammonium derivatives, 53 and fromzinc, manganese, etc., by he~amethylenetetramine.~~37 0.Procke, Coll. Czech. Chem. Comm., 1930, 2, 593; A., 1930, 1546.38 A. Stock, Naturwiss., 1931, 19, 499; A., 1025 ; A. Stock, H. LUX, F.Cucuel, and F.Gerstner, 8. angew. Chem., 1931, 44, 200; A., 588; B. L.Moldavski, J . Appl. Chem. Russia, 1930, 3, 955; A., 589.39 M. Teitelbaum, 2. anal. Chem., 1930, 82, 366; A., 188.40 N. A. Valiaschko and P. K. Virup, Ukraine Chem. J., 1930, 5, (Sci.),41 S. G. Clarke, Analyst, 1931, 56, 82; A., 590.42 B. S. Evans, ibid., p. 171 ; A., 590.43 R. Holtje, 2. anorg. Chem., 1931, 198, 287; A., 928.44 T. J. Ward, Analyst, 1930, 55, 630; A., 55; J. P. Mayrand, J . Amer.Pharm. ASSOC., 1931, 20, 637; A., 1024.4 5 R. Lang, 8. anal. Chem., 1931, 85, 176; A., 1258.46 L. A. Xarver and I. M. Kolthoff, J . Amer. Chem. Xoc., 1931, 53, 2902;A., 1141. 4 7 Idem, ibid., p. 2906; A., 1141.4 8 C. J. Xchollenberger, ibid., p. 88; A., 328; 0. Rothe and A.P. Sobrinho,Rev. brasil. Chim., 1929, 1, 129; A., 814.49 L. Szebellddy, Magyar Chem. Pol., 1930, 36, 40; A., 188.6o J. Knop and 0. Kubelkov&, 8. anal. Chem., 1931, 85, 401 ; A., 1261.51 W. D. Bonner and H. Romeyn, jun., I n d . Eng. Chem. (Anal.), 1931, 3,52 A. JilekaridV. Vicovskf, Coll. Czech. Chem. Comm., 1931,3,379 ; A., 1261.53 B. golsja and V. Matovinovid, Arhiw Herniju, 1931, 5, 232; A., 1260.54 1’. Ray, A. K. Chattopadhya, and D. Bhaduri, 2. anal. Chem., 1931,275; A., 702.85; A., 454.86, 13; A., 1281ANaLYTICAL CHEMISTRY. 195If iron and nickel are present, a single treatment with hypobro-mite does not suffice to oxidise chromium salts completely,55 butthey can be so oxidised by perchloric acid.56 Observations aremade on the determination of the oxide content of aluminium,57and on the precipitation of aluminium, chromium, and iron bypotassium cyanate.58 Aluminium may be precipitated by hydrazinecarbonate. 59The precipitation of manganese salts by water-soluble carbon-ates,60 the oxidation by persulphate in presence of silver salts,61and precipitation as manganese ammonium phosphate G2 have beenexamined. Precautions to be observed during precipitation ofcobalt 63 and nickel 64 as sulphide and subsequent conversion intometal and oxide respectively are enumerated, and also in the cobaltthiocyanate colorimetric comparison.65A scheme for the determination of zinc combined in mixtures asoxide, silicate, ferrite, sulphate, and sulphide is presented.66 Smallconcentrations of lead do not interfere with the precipitation ofsmall quantities of zinc by S-hydroxyq~inoline.~~Following precipi tation of oxalate, an alkalimetric titration isapplied to small amounts of calcium.68 Calcium, barium, andstrontium, present in pairs, itre separated by the varying solubilityof their bromides in isobutyl d ~ o h o l .~ ~ For precipitation of calciumas oxalate in presence of arsenate, a slight excess of ammonia a thigh temperature is recommended.70 For micro-determination,5 5 E. Schulek and A. Dbzsa, Z. anal. Chem., 1931,86, 81; A., 1262.5+3 L. H. James, Ind. Eng. Chem. (Anal.), 1931, 3, 258; A . , 1026.5 7 A. M. Shandorov, Tzwet. Met., 1930, 672; A . , 813: H. Lowenstein, 2.5 8 B. J. F. Dorrington and A. M. Ward, Analyst, 1930, 55, 625; A ., 56.59 A. Jilek and J. Lukas, Chem. Listy, 1930, 24, 365; A . , 1930, 1547.6O Idem, ibid., 1931, 25, 225, 249; A., 927; Coll. Czech. Chem. Comm., 1931,3, 1S7; A . , 702.61 R. Lang and F. Kurtz, 2. anal. Chem., 1931, 85, 181; A., 1261; J. H.van der Meulen, Chem. .WeekbZad, 1931, 28, 377; A., 927.62 P. Nuka, Latwij. Uniw. RaEsti, 1931, 2, 1 ; A., 1142.63 M. M. Haring and M. Leatherman, J. Amer. Chem. SOC., 1930,52, 5135;64 M. M. Haring and B. B. Westfall, ibid., p. 5141; A., 325.6 5 E. S. Tomula, 2. anal. Chem., 1931, 83, 6 ; A., 454.66 V. Tafel and G. Sille, 2. angew. Chem., 1930, 43, 948; A . , 1930, 1545;13’ M. E. Stas, Pharm. Weekblud, 1931, 68, 93; A . , 453.6 8 C. H. Fiske and E. T. Adams, J. Amer. Chem. SOC., 1931, 53, 2498;A., 1024; C. H.Fiske and M. A. Logan, J. Biol. Chem., 1931, 93, 211; A.,1342.69 L. SzebellBdy, Magyar Chenz. Pol., 1929, 35, 59, 63, 100; A., 186, 187.70 J. T. Dobbins and W. M. Mebane, J . Amer. Chern. SOC., 1930, 52 4285;anorg. Chem., 1931, 199, 48; A., 1025.A., 325.1931, 44, 792; A., 1260.A., 56196 FOX AND ELLIS:calcium is precipitated as triple nitrite with potassium and nickel,71as ~ x a l a t e , ~ ~ or as picrolonate; 73 a method in which calcium andmagnesium are titrated in the same solution is specially suited forthe analysis of dolomite.74 Calcium may conveniently be separatedfrom magnesium by precipitation as molybdate. 75 Direct volu-metric methods for barium depend upon the use of sodium rhodiz-onate as indicator 76 and upon the fact that potassium chromatereacts alkaline to bromothymol-blue and phenol-red.77 Variousmethods of determination of strontium a,nd of its separation fromcalcium are reviewed.78 Investigations on magnesium may bedivided into those using phosphate 79 and those involving use of8- hydroxyquinoline. 8OVarious modifications and adaptations of the triple acetatemethod for sodium and the cobaltinitrite method for potassium s2have been made. The direct sulphate method gives low resultsin the presence of 5-substituted barbituric acids.83 Other methods71 M. Mousseron, Bull. SOC. Chim. biol., 1930, 12, 1014; A., 1930, 1543;ibid., 1931, 13, 831 ; A., 1259.72 L. Velluz and R. Deschaseaux, ibid., p. 797; A., 1259; Compt.rend.SOC. Biol., 1930, 104, 976 ; A., 588.73 R. Dvorzak and W. Reich-Rohrwig, 2. anal. Chem., 1931, 88, 98; A.,1259.74 K. L. Maliarov, J . Russ. Phys. Chem. SOC., 1930, 62, 1529; A., 56;Mikrochem., 1931, 9, 132; A., 588; compare also G. A. Pantschenko, UkraineChem. J., 1930, 5, (Sci.), 187; A., 327.7 5 R. C. Wiley, Ind. Eng. Chem. (Anal.), 1931, 3, 127; A., 701.' 6 L. Zombory, Magyar Chem. Pol., 1929, 35, 90; A., 187.7 7 S. Balachovski, 2. anal. Chem., 1930, 82, 206; A., 1930, 1544.7 8 W. Noll, 2. anorg. Chem., 1931, 199, 193; A., 1259.'9 J. I. Hoffman and G. E. F. Lundell, Bur. Stand. J . Res., 1930, 5, 279 ;A . , 55; M. Javillier and D. Djelatides, Ann. Palsif., 1931, 24, 133; A., 701;V. NjegovanandV.Marjanovid, Arhiv Hemiju, 1931,5,243; A., 1259; idem, 2.anal.Chem., 1930, 82, 154; A., 1930, 1544; J. Majdel, ibid., p. 425; A.,452.J.C.RedmondandH.A.Bright,Bur.Xtand. J.Res., 1931,6,113; B.,396;F. L. Hahn, 2. anal. Chem., 1931,86, 153; A., 1259; W. A. Hough and J. B.Ficklen, J . Amer. Chem. SOC., 1930,52,4752; A., 327; K. Nehring, 2. Pfla<nz.Dung., 1931, 21, [A], 300; A., 1142; R. Berg, W. Wolker, and E. Skopp,Mikrochem., Emich Festschr., 1930, 18; A., 1930, 1546.A. M. Butler and E. Tuthill, J . Biol. Chem., 1931, 93, 171; A., 1342;J. T. Dobbins and R. M. Byrd, J . Amer. Chem. SOC., 1931, 53, 3288; A.,1259; E. R. Caley and D. V. Sickman, ibid., 1930, 52, 4247; A., 56; A.Blenkinsop, J . Agric. Sci., 1930, 20, 511; A., 186; R. A. McCance and H. L.Shipp, Biochem. J . , 1931, 25, 449; A., 926.82 J.Fischer, Biochem. Z . , 1931, 238, 148; A., 1259; R. A. Herzner,ibid., 237, 129; A., 1259; P. J. Van Rysselberge, I n d . Eng. Chem. (Anal.),1921, 3, 3; A., 452; P. N. Grigoriev and S. S. Korol, J . Chem. I d . , Russia,1931, 8, 68; A., 700.83 G. W. Collins, I d . Eng. Chem. (Anal.), 1931, 3, 291; A,, 1024ANALYlTCAL CHEMISTRY. 197for potassium depend upon titration of the acid tartrate,s4 uponcolorimetric comparison of the picrate,s5 and upon the use of lithiumchloroplatinate. 86 To convert alkali sulphates into chlorides insilicate analysis, they are heated with hydrazine hydrochloride ; 1 3 ~small quantities of alkalis are separated from acids insoluble inwater, e.g., tungstic acid, by electrodialysis.88Beryllium may be separated from aluminium by means of guan-idine carbonate; 89 the sulphite process of separating these twoelements has been reinve~tigated~~o and further details given forthe microanalysis of beryllium silicate rocks.91 For low concen-trations of titanium, accurate results by the colorimetric methodare obtainable by comparing solutions of identical c01our.~~ Furtherseparations of gallium by means of camphoric acid are rec0rded.~3For molybdenum, the permanganometric method 94 and precipit-ation as lead molybdate95 have been examined.In the presenceof molybdate, tungsten is determined colorimetrically by meansof rhodamine-B, otherwise a quinol sulphate solution may be used.96Potassium chloride acts as an anti-oxidant, enabling manipulationof uranous compounds to be carried out within an hour or so in thepresence of air ; 97 zirconium is quantitatively precipitated byexcess of selenious acid from hot slightly acid solutions.98 I n theseries of investigation on the analytical chemistry of tantalum,niobium, and their mineral associates, a detailed technique isdescribed 99 and also the separation of titanium from zirconiumand hafnium.1 Quantitative conversion of lanthanum oxalateinto oxide does not occur below 800";.coprecipitation of basicL. Clarke and J. M. Davidson,.Ind. Eng. Chem. (Anal.), 1931, 3, 324;A . , 1024.8 5 E. R. Caley, J . Amer. Chem. SOC., 1931, 53, 539, A., 452.8 c G. F. Smith and A. C. Shead, ibid., p. 947; A., 587.W. Mylius, Sprechsaal, 1930, 63, 972; A ., 700.8 8 G. Heyne, 2. angew. Chem., 1931, 44, 328; A., 926.89 A. Jilek and J. Kota, Coll. Czech. Chem. Comm., 1931, 3, 336; A., 1024.91 H. Thurnwald and A. A. Benedetti-Pichler, Mikrochem., 1931, 9, 324;ga H. Ginsberg, 2. anorg. Chem., 1931, 198, 162; A . , 814.93 S. Ato, Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1931, 15, 289; A,,v4 T. Doring, 2. anal. Chem., 1930, 82, 193; A . , 1930, 1548.95 H. A. Doerner, Metal Id., London, 1930, 37, 444; A . , 589.96 G. Heyne, 2. angew. Chem., 1931, 44, 237; A . , 589.9 7 C . Ouellet, Helv. Chim. Acta, 1931, 14, 967; A . , 1262.O 8 S. G. Simpson and W. C. Schumb, J. Amer. Chem. SOC., 1931, 53, 921;99 W. R. Schoeller, Analyst, 1931, 56, 304; A., 814.A. Travers and Schnoutka, Compt. rend., 1931, 192, 285; A., 452.A ., 927.927.A . , 590.A. R. Powell and W. R. Schoeller, ibid., 1930, 55, 605; A., 57198 FOX AND ELLIS:chloride may be avoided by adding the lanthanum solution to alarge excess of soda or ammonia.2Full details are given of a procedure recommended for the de-termination of ~ s m i u m . ~ Special attention has been given to thedetermination of small quantities of ~ i l v e r . ~ The chemical reactionsof polonium are reviewed, with special reference to their analyticalsignificance.Iodometric and gravimetric methods are described for thedetermination of small amounts of thallium, the former beingapplied particularly to organs.The boric acid-alcohol flame coloration has been applied quantit-atively.8 Boric acid may be separated from dilute sulphuric acidsolutions of heavy metal salts by distillation with methyl alcohol ;this process has been used for natural waters and plant materials.1°Carbon monoxide is oxidised to dioxide by a suspension of iodinepentoxide in oleum,ll by copper oxide deposited on quartz,12 andby silver oxide.13 A number of modified methods of determiningcarbon dioxide are described; l4 the aniline method and the sodiumiodide-acetone method have been adapted to give concordant resultsfor carbonyl chloride in presence of other chlorine compounds.152 I.M. Kolthoff and (Miss) R. Elmquist, J . Amer. Chem. SOC., 1931, 53,3 R. Gilchrist, Bur. Stand. J . Res., 1931, 6, 421; A., 814.4 E. Schulek, Mikrochem., Emich Fest,schr., 1930, 260; A., 1930, 1543;J.Golse, Bull. SOC. Pharm. Bordeaux, 1930, 68, 53; A., 452 : C. Egg, Schweiz.med. Woch., 1929, 59, 84; A,, 186.1225; A., 702.5 M. Guillot, J . Chim. physique, 1931, 28, 14; A., 591.0 R. Fridli, Magyar Gy6. Thrsas. &rt., 1929, 5, 479; A., 56; Deut. 2. yes.7 L. Moser and W. Reif, Mikrochem., Emich Festschr., 1930, 215; A.,8 W. Stahl, Latvij. Univ. Raksti, 1930, 1, 369, 400; A , , 326; 2. anal.8 E. Schulek and G. Vastagh, ibid., 1931, 84, 167; A., 812.gerichtl. Med., 1930, 15, 478; A., 328.1930, 1545.Chem., 1931, 83, 268, 340; A., 587.10 L. V. Wilcox, Ind. Eng. Chem. (Anal.), 1930, 2, 358; A., 1930, 1543.11 H. A. J. Pieters, Chem. Weekblad, 1931,28, 335; A., 812; 2. anal Chem.,1931, 85, 50; A., 1258.12 A. Schmidt, 2.angew. Chem., 1931, 44, 152; A., 926; H. A. J. Pieters,2. anal. Chem., 1931, 85, 113; A., 1258.13 Idem, ibid.; W. Manchot and G. Lehmann, Ber., 1931, 64, [B], 1261;A., 926.l4 C. A. Jacobson and J. W. Haught, Bull. West Va. Univ. Sci. ASSOC.,1930, 2, No. 4, 8; A., 700; E. M. Emmert, J . Assoc. Off. Agric. Chem., 1931,14, 386; A., 1142; U. Boklund, Biochem. Z., 1931, 233, 478; A., 1024;J. Lindner and F. Hernler, Mikrochem., Emich Festschr., 1930, 191; A.,1930, 1543; M. Nicloux, Compt. rend. SOC. Biol., 1929, 101, 182; A., 186.15 J. C. Olsen, G. E. Ferguson, V. J. Sabetta, and L. Scheflan, Ind. Eng.Chem. (Anal.), 1931, 3, 189; A., 700ANALYTICAL CHEMISTRY. 199Hydrogen is readily absorbed by a silver permanganate reagent ; l6two manometric methods for the determination of hydrogen peroxideare described.17 Work on helium is continued.18Continuing his bromo-iodometric investigations, J.H. van derMeulen 19 describes methods (a) of determining iodate and bromatetogether, ( b ) of determining iodate, bromate, and chlorate together,(c) of oxidising bromide to bromate with hypochlorite, ( d ) of destroy-ing excess of hypochlorite by boiling with sodium formate or alittle osmic acid, ( e ) of reducing chlorate to chloride by arsenite,with osmate as catalyst, (f) or by ferrous sulphate in presence ofhydrobromic acid and osmate as catalyst. Other papers in thehalogen group deal with bromides,21 iodine and iodides,22and fluorides.23Some conditions for determining nitrates by phenoldisulphonicacid are laid down.24 Nitrates are quantitatively reduced electro-l6 F.Hein and W. Daniel, Chem. Fabr., 1931, 381; A., 1256.l7 A. Fujita and T. Kodama, Biochem. Z., 1931, 232, 15; A., 699.F. Paneth and W. D. Urry, Mikrochem., Emich Festschr., 1930, 233;A., 1930, 1543; Z. physikal. Chem., 1931, 152, 110, 127; A., 327; ibid.,Bodenstein Festband, 1931, 145; A., 1258; V. A. Sokolov, Neft. Khoz., 1930,19, 292 ; A., 452.l9 Chem. Weekblad, 1930, 27, ( a ) p. 578; ( b ) p. 618; 1931, 28, (c) p. 82;( d ) p. 235; ( e ) p. 258; (f) p. 348; A., 1930, 1542; 1931, 55, 325, 699, 699,811.2o A. V. Frost, Trans. Inst. Pure Chem. Reagents, 1929, No. 300, 187; A.,1930, 1541; G. G. Longinescu and T. J. Pirtea, Bul. Chim. Soc. RomlinciStiin., 1928, 31, 77; A., 585; I.E. Orlov, Z. anal. Chem., 1931, 84, 185;A., 811; A. B. Keys, J., 1931, 2440; A., 1257; V. N. Kolitscheva and R. V.Teis, J . Russ. Phys. Chem. Soc., 1930, 62, 1957; A., 450 : 0. TomiEek and 0.ProEke, Coll. Czech. Chem. Comm., 1931, 3, 116 ; A., 450 ; H. RUOSS, Z. anal.Chem., 1930,81, 385 ; A., 1930, 1541 ; Cousin and DUfour, J . Pharm. Chim.,1930, [viii], 12, 439; A., 55.21 Z. Szabb, Z. anal. Chem., 1931, 84, 24; A., 811; B. S . Evans, Analyst,1931, 56, 590; B., 1009 ; M. Bobtelsky and R. Rosovskaja-Rossienskaja,2. anorg. Chem., 1931, 199, 283; A., 1257.22 R. W. Teiss, Z. anal. Chem., 1930, 82, 116; A., 1930, 1542; H. Ditz,Z. anorg. Chem., 1930, 194, 147; A., 185; F. L. Hahn, ibid., 1931, 195, 75;A., 325; H. A. Liebhafsky, J .Amer. Chem. SOC., 1931, 53, 165; A., 325;R. E. Remington, J. F. McClendon, and H. von Kolnitz, ibid., p. 1245; A.,699; P. Fleury and J. Courtois, BUZZ. SOC. chim., 1931, [iv], 49, 860; A.,1023.23 A. Kurtenacker and W. Jurenka, Z. anal. Chem., 1930, 82, 210; A.,1930, 1542; M. Karasiliski, Bull. Acad. Polonaise, 1931, [A], 143; A., 1257;P. Mougnaud, Compt. rend., 1931, 192, 1733; A., 1023; A. V. Frost, Trans.Inst. Pure Chem. Reagents, 1931, 10, 53; A., 925; G. Batchelder and V. W.Meloche, J . Amer. Chem. Xoc., 1931, 53, 2131 ; A., 925 ; H. Ginsberg, Chem.-Ztg., 1931, 55, 608.24 B. A. Skopintzev, J . Appl. Chem. Russia, 1930, 3, 747; A., 326; Z.anal. Chem., 1931, 85, 244; A., 1257200 FOX AND ELLIS:lytically at a copper or nickel cathode.25 A phosphate buffer ofpH 7.4 is recommended for the recovery of free ammonia fromammonium chloride and sulphate solutions ; 26 oxidation of am-monia to nitrogen by bromine is quantitative in solutions of p=76---9.5.27 A volumetric method for very small quantities ofammonia, especially in waters, is described.28 Alkali azides aretitrated with silver nitrate in presence of potassium chromate ; 29hydrazine and semicarbazide may be determined by oxidationwith potassium iodateY30 and nitrites colorimetrically with rivanol ; 31the reaction between nitrite and iodide has been examined.32Several papers deal with the determination of phosphoric acid ; 33and methods are given for the removal of phosphate ions fromsolution in analysis.34 Hypophosphites and arsenites are deter-mined by reaction with mercuric chloride.35 Potassium perman-ganate is applied colorimetrically as a reagent for lower oxides inphosphoric oxide.36Modifications have been introduced into certain methods ofdetermining persulphate to increase their accuracy ; 37 a schemeis proposed for mixtures of Caro’s acid, persulphate, and hydrogenperoxide.38 Further observations are made on volumetric methodsfor ~ulphates,3~ and on the precipitation as barium sulphate in the26 L.Szebellhdy and B. M. Schall, 2. anal. Chem., 1931, $6, 127 ; A., 1257.26 M. S. Nicholls and M. E. Foote, Ind. Eng. Chem. (Anal.), 1931, 3, 311 ;27 B. Levy, 8. anal. Chem., 1931, 84, 98; M. Tschepelevetzky, S. Posd-A., 1023.niakova, and R. Fein, ibid., p.106; A., 1024.S. K. Hagen, ibid., 83, 164; A., 586.2s A. Majrich, Chem. Obzor, 1930, 5, 3; A., 186.3O V. Hovorkrt, Coll. Czech. Chem. Comm., 1931, 3, 285; A., 925.31 W. M. Rubel, 8. Unters. Lebensm., 1930, 60, 588; A., 586.32 C. A. Abeledo and I. M. Kolthoff, J. Amer. Chem. Soc., 1931, 53, 2893;A., 1142.33 A. del Campo, Anal. Pis. Quim., 1930,28, 1153; A., 55; H. T. Buchererand F. W. Meier, 2. anal. Chem., 1931, 85, 331 ; A., 1258; H. Thurnwald andA. A. Benedetti-Pichler, ibid., 86, 41 ; A., 1258 ; S. L. Lieboff, J . Lab. Clin.Med., 1931,16,495; A., 1258; R. Biazzo, Ann. Chim. Appl., 1931,21,21, 75;A., 452; ibid., p. 105; A., 700; G. DenigBs, Bull. SOC. Pharm. Bordeaux,1930, 68, 1 ; A., 927 ; M. Ishibashi, Chikashige Anniv. Vol., 1930, 1 ; A., 586 ;A.von EndrBdy, 2. anorg. Chem., 1930,194, 239; A., 186.34 A. Kegans, Latvij. Univ. Raksti, 1929,1, 65; A . , 1930, 1543; J. Bougaultand E. Cattelain, J. Pharm. Chim., 1931, [viii], 14, 97; A., 1142.35 A. Ionesco-Matiu and (Mme.) A. Popesco, ibid., 13, 12; A., 326.36 J. W. Smith, J., 1931, 528; A., 587.37 A. Kurtenacker and H. Kubina, 2. anal. Chem., 1931, $3, 14; A . , 452.38 K. Gleu, 2. anorg. Chem., 1931, 195, 61; A., 326.I. M. Kolthoff and E. 13. Sandell, Ind. Eng. Chem. (Anal.), 1931,3,115; A.,451 ; Chatron, J. Pharrn. Chim., 1931, [viii], 13,244; A . , 586; M. Dominikiewicz,Bull. Trav. Dep. Chim. Inst. Hyg. Ztat. (Poland), 1930, 31, No. 1, 3; A., 185ANALYTICAL CHEMISTRY. 201presence of lead salts 40 and of various chromium compound^.^^ Abuffered ammonia solution is added prior to the oxidation ofthiocyanate by iodine.42With the view of application to the analysis of natural selenides,methods have been devised for determination of copper 43 andsilver selenites 44 in the presence of the corresponding selenides.For the rapid precipitation of selenium, large quantities of hydrazinehydrochloride are recommended.45 Both selenious and silicicacids may be determined colorimetrically by reaction with pyrrolealthough the colour fades rather rapidly.46 A nitric-perchloricacid mixture is used for the determination of silica in vegetablesubstance^.^'Organic Analysis.Qualitative.-For purposes of identification of various phenolsthere are described the corresponding phenoxyacetic acids 48 and3 : 5-dinitrobenzoates ; 49 of fatty acids, the p-bromophenacylesters and alkylbenziminazoles; 51 of alcohols, the p-nitro-phenylurethanes ; 52 of alcohols and phenols, the p-xenylcarb-amates; 53 of primary and secondary alcohols and certain phenols,the hydantoin-3-acetates; 54 of carbonyl compounds, the 2 : 4-dinitrophenylhydrazones ; 55 of halides, as 3 : 5-dinitrobenzoates 5640 B.TBzak, Arhiv Henziju, 1930, 4, 7 8 ; A., 1930, 1542.41 E. A. Eikitina and A. V. Ihbajeva, Trans. Inst. Pure. Chem. Reagents,42 H. A. Page1 and H. J. Koch, J. Amer. Chem. SOC., 1931, 53, 1774; A . ,43 W. Geilrnann and F. W. Wrigge, 2. anorg. Clbem., 1931, 197, 353; A.,44 F. W. Wrigge, ibid., p. 369; A., 813.*5 E. Benesch and E. Erdheim, Chem.-Ztg., 1930, 54, 954; A., 185; K.4 6 R.Berg and M. Teitelbaum, Mikrochem., Emich Festschr., 1930, 23;4' L. Lematte, G. Boinot, E. Kahane, and (Mme.) M. Kahane, Compt. rend.,48 C . F. Koelsch, J. Amer. Chem. Xoc., 1931, 53, 304; A . , 345.49 M. Phillips and G. L. Keenan, ibid., p. 1924; A., 837.5O S . G. Powell, ibid., p. 1172; A., 621.51 R. Seka and R. H. Muller, Monatsh., 1931, 57, 97; A . , 600.5 2 R. L. Schriner and R. F. B. Cox, J . Amer. Chem. SOC., 1931, 53, 1601;53 G. T. Morgan and A. E. J. Pettet, J., 1931, 1124; A., 834.6 4 R. Locquin, V. Cerchez, and A. A. Policard, Bull. SOC. chim., 1931, [iv],5 5 0. L. Brstdy, J., 1931, 75tj; A., 937.5 6 C. L. Tseng and E. J. H. Chu, Nat. Centr. Univ. Sci. Rep., [A], 1930,1931,10, 20; A., 925.811.813.Wagenmann and H.Triebel, Metall u. Erz, 1930, 27, 231 ; A., 186.A., 1930, 1546.1931,192, 1459; A., 926.A . , 709.49, 595, 600, 602, 607; A., 966.1, 9 ; A., 504.G 202 FOX AND ELLIS:and as anilides; 57 of ethers, as alkyl 3 : 5-dinitrobenzoates orbromo-derivatives. 58The sensitivity of various methods, old and new, for the detectionof carbon disulphide has been a~certained.5~ The blue colorationproduced with iodine and lanthanous salts is a delicate test foracetic acid; benzoic acid and homologues of acetic acid reactsimilarly or inhibitatively.60 Colour reactions are described forcertain higher aliphatic acids,61 pnaphtho1,62 phenols generally,63and o-dihydroxyphenols in particu3ar764 for certain diamino- andnit roamino - di phen y 1 sul p hides , 65 gl y oxaline derivatives and tyro -sine,66 thiolglyoxalines,67 morphine,68 adrenaline,69 salicylic acidand salol, 7O phenyl o-aceto~ybenzoate,~~ tannin, gallic acid, andpyrogallol, 72 quinones,73 aromatic amines 7* and the toluidines inparticular, '5 ephedrine,76 cystine,77 eugenol and clove carbo-57 A.M. Schwartz and J. R. Johnson, J . Amer. Chem. Soc., 1931,53, 1063;5 8 H. W. Underwood, jun., 0. L. Baril, and G. C. Toone, ibid., 1930, 52,59 F. Feigl and K. Weisselberg, 2. anal. Chem., 1931, 83, 93; A., 638;6o E. Tschirch, Oesterr. Chem.-Ztg., 1931, 34, 38; A., 601; D. Xruger and61 L. Ekkert, Pharm. Zentr., 1931, 72, 228; A., 710.62 G. de Haas, Pharm. Weekblad, 1931, 68, 29; A., 347.63 C. D. Leake, Proc.SOC. Exp, Biol. Med., 1930, 28, 148; A., 856; V. E.Levine, J . Amer. Pharm. ASSOC., 1931, 20, 537; A., 972 ; &I. Franqois and(Mlle.) L. Seguin, Bull. Soc. chim., 1931, [iv], 49, 650; A., 972; L. Rosen-thaler, Pharm. Ztg., 1931, 76, 8 8 8 ; A., 1174.A., 597.4087; A., 1930, 1554.S . L. Malowan, ibid., 84, 406; A., 1078.E. Tschirch, Mikrochem., 1930, 8, 337 ; A., 335.64 J. H. Quastel, Analyst, 1931, 56, 311 ; A., 856.G5 H. H. Hodgson and W. Rosenberg, J . Soc. Dyers Col., 1930, 46, 267;A., 84.G6 E. Gebauer-Fulnegg, 2. physiol. Chem., 1930, 191, 222; A., 1930, 1605;J. A. Shnchez, Semana mdd., 1930, I , 1579; A., 108.6 7 G. Hunter, J., 1930, 2343; A., 1930, 1596.O 8 F. Bamford, Analyst, 1931, 56, 586; A., 1312; L. Rossi, Anal.Farm.69 B. Azzolini, Boll. cJzim.-farm., 1931, 70, 665; A., 1315.70 L. Ekkert, Pharm. Zentr., 1930, 71, 744; A., 88.71 H. Szancer, ibid., 1931, 72, 68; A., 351.72 M. N. A. de Celsi and S. A. Celsi, AnaZ. Farm. Bioquim., 1931, 2, 56;73 R. Craven, J., 1931, 1605; A., 972.74 I. de Paolini, Atti R. Accad. Sci. Torino, 1930, 65, 201 ; A., 638.75 W. H. Patterson, J., 1930, 2401 ; A., 1930, 1605.7 6 W. H. Hartung, F. Crossley, and J. C. Munch, J . Pharm. Chim., 1931,[viii], 13, 474; A., 724; J. Sivadjian, ibid., 1930, 12, 266; A., 1930, 1460;idem, ibid., 1931, 14, 61 ; A., 1079.Bioquim., 1930, 1, 106; A., 1319.A., 1174.7 7 J. A. SAnchez, Semana mt?d., 1930, 11, 31 ; A., 1930, 1563.78 H. Szancer, Bull. Sci. pharmacol., 1929, 36, 611 ; A., 1930, 1605203 ANALYTICAL CHEMISTRY.hydrates and related benzene, naphthalene, eft-,p-benzoquinone, and quinoline,go and the aitro-group.slThe Scott-Wilson reagent for acetone and acetaldehyde can bemade specific for the Micro-crystallographic data aregiven for mesaconic acid and certain of its derivatives; 83 thefluorescent properties of umbelliferone enable its formation frommalic acid and resorcinol to serve as specific tests for these sub-stance~.~* Differentiation of cyclic monophenols and monoaminesfrom polyphenols and polyamines is effected by means of phospho-tungstic and phosphomolybdic reagents.85 Triketohydrindenehydrate is not a trustworthy reagent for the products of proteinhydrolysis.86 The action of iodine and bromine on unsaturatedbarbituric acid derivatives in bicarbonate solution is described ; 87" veronalides " are diagnosed micro-crystalloscopically.88Alkaloids are classified in nine groups according to their sensitivitytowafds precipitating agents, their solubility in water and thebasic strength of the free alkaloids; 89 a tabulation is made of themicrochemical reactions of 78 alkaloids with a number of reagents.90Limiting concentrations for the micro-precipitation of alkaloids bysodium alizarinsulphonate are recorded ; 91 sulphonic acids of otheranthraquinone derivatives form crystalline precipitates with organicbases.92 Microchemical methods are described for the detectionof strychnineJS3 I-ephedrine and ephet~nine,~~cytisine,~~ echinopsine,96nicotineJS7 colchi~ine,~~ piperineJ99 and choline.1 The formationJ.S. Hepburn and M. Lazarchick, Amer. J. Pharm., 1930,102,560; A., 69.P. K. Bose, Analyst, 1931. 56, 504; A., 1148.8o L. Ekkert, Pharm. Zentr., 1931, 72, 51; A., 375..82 L. Klinc, Arhiv Hemiju, 1931, 5, 212; A., 1273.83 13. €3. Mottern and G. L. Keenan, J . Amer. Chem. SOC., 1931, 53, 2347 ;84 L. Columbier, Ann. Palsif., 1931, 24, S9; A., 698.8 5 A. Marenzi, Anal. Farm. Bioquim., 1930, 1, 99; A., 375.86 H. Gardner, Lancet, 1930, ii, 525; A., 972.*' J. Bougault and J. Guillon, Compt. rend., 1931, 193, 463; A., 1308.8 8 G. Denighs, Mikrochem., 1931, 9, 316; A., 966.ee C. C. Fulton, J. Assoc. Off. Agric. Chem., 1930, 13, 491 ; A., 243.J. F. H. Amelink, Pharm. Weekblad, 1931, 68, 159, 211, 221; A., 504.91 L.Rosenthaler, Apoth.-Ztg., 1930, 45, 638; A., 375.s 2 W. Zimmermann, 2. physiol. Chem., 1930, 188, 180; 189, 155; 192,93 V. D. Gnesin, Farm. Zhur., 1930, 293; A., 1079.94 L. Rosenthaler, 2. anal. Chem., 1931, 86, 61 ; A., 1319.s5 G. Klein and E. Farkass, Oesterr. Bot. Z., 1930, 79, 107; A., 213.96 G. Klein and F. Schusta, ibid., p. 231; A., 639.9 7 G. Klein and E. Herndlhofer, ibid., 76, 222; A., 639.# * G. Klein and G. Pollauf, ibid., 1929, 78, 251 ; A., 778.SY G. Klein and M. Krisch, ibid., p. 257; A., 778.G. Klein and A. Zeller, ibid., 79, 40; A., 778.A., 1036.124; A., 1930, 941, 1170, 1605FOX AND ELLIS: 204of the substance responsible for the thalleioquinine reaction isretarded by a decrease in p,.2Reactions of choline and le~ithin,~ creatine and ~reatinine,~a l a n i ~ ~ e , ~ antipyrine and pyramidone,6 narceine,' dulcine,s andmezcaline are given.Sodium nitroprusside gives colour reactionswith a variety of organic cornpounds.lO Iodine tetrachloride isused for the microchemical identification of a number of alkaloids ; l1p-toluenesulphonic acid is suggested as condensing agent for thedetection of alcohols by the odour of their esters, and isopropylalcohol can be recognised in presence of ethyl alcohol by its reactionwith protocatechualdehyde. l2An account is given of the application of micro-sublimationmethods to the identification of small quantities of materials, l3and an apparatus described for the extraction of benzoic and otheraromatic acids.l4&uantitative.-Sulphur is eliminated in direct combustions forcarbon by a plug of asbestos upon which red lead has been~ub1imed.l~The extent to which combustion tubes and the materialsused in organicelementary analysis yield water on ignition has been investigated ; l6advantages are claimed €or copper tubes in corn bust ion^.^^ Investig-ations on the elementary analysis of organic compounds may be re-viewed under the following heads : carbon and hydrogen,18nitrogen, l9J. Eisenbrand, Arch. Phwm., 1931, 269, 65; A., 639.J. A. Shchez, Xemana ma., 1930, I, 1416; A., 75.Idem, ibid., 11, 616; A., 246.Idem, ibid., 1931, I, 651 ; A., 1042.M. Ribitre, J. Phurm. Chim., 1930 [viii], 12, 444; A., 99. ' J. A. Sanchez, Anal. Farm. Bioquim., 1931, 2, 68; A., 1174.Idem, ibid., p.63; A., 1174.L. Rosenthaler, Pharm. Ztg., 1931, 76, 653; A., 1318.lo T. Pavolini, Boll. chim.-farm., 1930, 69, 713; A., 1930, 1605.l1 L. Rosenthaler, Pharm. Ztg., 1931, 76, 524; A., 857.l2 Idem, ibid., 775; A., 971.l3 A. Chalmeta, Anal. Pis. Quim., 1930, 28, 1407; A., 246.l4 A. N. Leather, Analyst, 1931, 56, 299; A., 856.l5 W. H. Blatchley, I d . Eng. Chem. (Anal.), 1931, 3, 13; A., 503.lG J. Lindner, Ber., 1931, 64, [B], 1560; A., 1078.N. Klatschin, 2. anal. Chem., 1930, 82, 133; A., 1930, 1604.H. Lieb and H. G. Kraineck, Mikrochem., 1931, 9, 367; A., 971 ; J. B.Niederl and J. R. Meadow, ibid., p. 350 ; A., 971 ; A. Verdino, ibid., p. 123 ;A., 638 ; A. Friedrich, ibid., p. 20 ; A., 374 ; M. Furter, ibid., p.27 ; A., 374 ;F. Herder, ibid., 1930, Emich Festschr., 148; A., 107; E. P. Griffing and C.L. Alsberg, J. Amer. Chem. Xoc., 1931, 53, 1037; A., 638; E. Stansfield andJ. W. Sutherland, Canadian J. Res., 1930, 3, 318; A . , 1930, 1604.W. J. Saschek, I n d . Eng. Chern. (Anal.), 1931, 3, 198; A., 700; N. %I.Stover and R. B. Sandin., ibid., p. 240; A., 1024; W. F. Allen, ibid., p. 239;A., 1024 ; 0. R. Trautz and J. B. Niederl, ibid., p. 151 ; A., 752 ; J. J. Rutgers,Cornpt. r e d . , 1931,193, 51 ; A., 1024; J. Schmidt and W. Maier, Ber., 1931ANALYTICAL CHEMISTRY. 205halogensY20 and phosphorus.21 A volumetric method of deter-mining methoxyl and ethoxyl groups is described 22 which mayalso be used on the micro-scale; z3 modifications are made inthe micro-Zeisel process to render i t applicable to polymethoxy-compound^.^* The Fuchs-Hunter-Edwards method for determiningcarboxyl groups is adapted for micro-w0rk.~5 The use of benzyl-alcoholic alkali is recommended for the determination of acetylgroups in substituted acetamides.26 Some errors in analyticalbromination have been investigated, and a process is detailed forthe measurement of organic unsaturation.27Oxidation of small amounts of ethyl alcohol with chromic acidgives results comparable with those obtained by the specific gravitymethod; 28 a modified micro-Zeisel process has been applied tothis alcoh01.2~ Reaction with ethyl formate and ethoxide to givesodium formate serves to prepare anhydrous alcohol and to deter-mine the water content of alcoh01.~0 A n account is given of theuse of Ilosvay’s reagent for the determination of traces of acetylene.31Reaction of formaldehyde or hexamethylenetetramine with methoneshould be effected in neutral solution.32 Modifications of existingmethods are made for the determination of solid saturated33 and64, [B], 778; A ., 752; F. Govaert, Natuurwetensch. Tijds., 1931, 13, 127;A., 856; idem, Mikrochem., 1931, 9, 338; A., 971; idem, Ann. Chim. analyt.,1931, [ii], 13, 229; A., 1142; J. C. Harral, Analyst, 1931, 56, 527; A., 1174;M. Weizmann, J. Yofe, and B. Kirzon, 2. physiol. Chem., 1930,192, 7 0 ; A.,1930, 1604; A. C. Anderson and B. N. Jensen, 2. anal. Chem., 1931, 83,114; A., 638; 0. R. Trautz, Mikrochem., 1931, 9, 300; A., 971.2o B.Bobradski, Rocz. Chem., 1931, 11, 301; 2. anal. Chem., 1931, 84,225; A., 856; F. Schulz, Coll. Czech. Chem. Cornm., 1931, 3, 281; A., 945.21 W. C. Davies and D. R. Davies, J . , 1931, 1207; A., 856..32 F. Viebock and A. Schwappach, Ber., 1930, 63, [ B ] , 2818; A , , 107.23 F. Viebock and C. Brecher, ibid., p. 3207; A., 246.?* (Miss) G. M. Ware, Mikrochem., 1930, 8, 352; A., 374.25 S. Tsurumi and Y. Sasaki, Sci. Rep. 176hoku Imp. Univ., 1930, 19, 681 ;A . , 504.26 S. Sabetay and J. Sivadjian, J. Pharm. Chim., 1931, [viii], 13, 530; A.,856.27 H. M. Buckwalter and E. C. Wagner, J. Amer. Chem. SOC., 1930, 52,5341 ; A., 193.28 S. G. Liversedge, Analyst, 1931, 56, 595; A., 1267; M. Nicloux, Compt.rend., 1931, 192, 985; A., 752; idem, Bull.SOC. Chim. biol., 1931, 13, 857;A., 1327.2D J. B. Niederl and B. Whitman, 2. anal. Chem., 1931, 86, 65 ; A., 1318.30 F. Adickes, W. Brunnert, and 0. Lucker, Ber., 1930, 63, [B], 2753; A.,61.31 W. Riese, 2. angew. Chem., 1931, 44, 701; A., 1318; see also E. Czak6,ibid., p. 388; A., 819; and E. Pietsch and A. Kotovski, ibid., p. 388 ; A., 819.32 V. Ionescu and C. Bodea, Bull. SOC. chim., 1930, [iv], 47, 1408; A . , 335.33 T. P. Hilditch and J. Priestman, Analyst, 1931, 56, 354; A., 935206 FOX AND ELLIS:of solid unsaturated34 fatty acids, and for Okey’s method forchole~terol.~~ Methods involving the use of iodine monochlorideor bromide are found to be unsuitable for the determination ofthe iodine value of cholesterol owing to substitution ; Kaufmann’smethod is preferred, with that of Rosenmund and Kuhnhenn assecond choice.36 A quantitative separation of saturated and un-saturated sterols depends on the fact that cholesterol dibromideis not precipitated by digitonin.37 Work on the oxidation of sugarsby iodine in presence of alkali,3* by ferri~yanide,~~ and by cupro-potassium carbonate solutions 4O has been extended.A colori-metric method with acid molybdate is applied to laevulose in presenceof certain other sugars ; 41 some factors governing the fermentationof polysaccharides are discussed.42The humic acid content of dilute solutions is ascertained bypermanganate oxidation under prescribed condition^.^^ The com-position of the phospho- and silico-tungstates of choline and alliedbases has been rec0rded.~4 The pDH at which phosphotungstateprecipitates of certain bases appear depends largely on the con-stitution of the base;45 reaction between nicotine and silico-tungstic acid, applied volumetrically, does not appear to be stoicheio-metric.46 Values of pH a t the end-point of the neutralisation ofalkaloid bases have been deduced, and suitable indicators for thetitration selected ; 47 colorimetric methods are described for mor-34 L.V. Cocks, B. C. Christian, and G. Harding, Analyst, 1931, 56, 368;35 M. Yasuda, J . Biol. Chem., 1931, 92, 303; A., 1318; M. E. Turner, ibid.,36 H. Werner, 2. Unters. Lebensm., 1931, 61, 331; A., 1318.37 R. Schonheimer, 2. physiol. Chem., 1930, 192, 7 7 ; A., 1930, 1616.35 G.M. Kline and S. F. Acree, Ind. Eng. Chem. (Anal.), 1930, 2, 413; A.,1930, 1560; Bur. Stand. J . Res., 1930, 5, 1063; A., 199.39 A. C. Hulme and R. Narain, Biochem. J., 1931, 25, 1051; A., 1274;E. M. Widdowson, ibid., p. 863; A., 1102; 0. Lehmann, Planta, 1931, 13,575; A . , 1038.40 H. A. Schuette and J. N. Terrill, J . Amer. Chem. SOC., 1930, 52, 4960;A . , 199.41 H. Bredereck, Ber., 1931, 64, [B], 1730; A . , 1039.42 E. Schmidt, M. Atterer, and H. Schnegg, Cellulosechem., 1931, 12, 235;43 D. J. W. Kreulen, Brennstoff-Chem., 1031, 12, 265; A., 1148.44 L. Lematte, G. Boinot, E. Kahane, and (Mme.) M. Kahane, J . Pharm.Chim., 1931, [viii], 13, 371; A., 606; Cornpt. rend., 1930, 191, 1130; A.,338.A., 935.p. 495; A., 1174; see R.Olrey, ibid., 1930, 88, 367; A., 1930, 1303.A., 1038.45 R. A. Peters, Biochem. J., 1930, 24, 1852; A., 374.46 B. Kasansky, 2. anal. Chem., 1931, 83, 107; A., 639.47 E. B. R. Prideaux and F. T. Winfield, Analyst, 1930,55,561; A., 246;compare also F. Reimers, Dansk Tidsskr. Farm., 1931, 5, 42; A., 752ANaLYTICAL CHEMISTRY. 207phine, heroine, and physo~tjgmine,~8 cryogenin,@ tryptophan,50strychnine, emetine, cinchonine, and quinine,51 cystine 52 and~ y s t e i n e . ~ ~ Serine in hot alkaline solution gives ammonia, glycine,alanine, and oxalic and lactic acids.54 The precipitate formedfrom choline with excess of gold chloride is stable to concentrationand can be washed with water.55 In dilute alcohol-ether solutionnovocaine, but not cocaine, is precipitated by picric acid; 56 amixture of chloroform and isopropyl alcohol is recommended forthe extraction of morphine from its aqueous s~spension.~~ Con-ditions are prescribed for the quantitative saponification of thelactone group in narcotine and santonin.58 An iodo-gasometricmethod for determining cysteine (or, after reduction, cystine) isdescribed.59Pyramidone is quantitatively precipitated by an excess of mercuricchloride ; antipyrine is precipitated also, but not quantitatively.60Mercurimetric methods have applied to citrates, salicylates, andbenzoates.61 Verley , and Bolsing’s method has been applied tothe determination of the hydroxyl group in castor oil and variousphenols.62 Determination of phenylhydrazine gasometrically isapplied to the evaluation of the carbonyl group of ketones andaldehydes; 63 the method involving formation of iodoform fromthe COMe group in acetone can be extended to many ketones con-taining this group.64Conditions for the alkalimetric titration of 2 : 4-dinitrophenol48 L.David, Pharm. Ztg., 1931, 76, 706; A., 972.50 T . Ruemele, 2. anal. Chem., 1931, 84, 81; A., 1079. I51 C. A. Rojahn and R. Seifert, Arch. Pharm., 1930, 268, 499; A., 1930,1605.52 M. X. Sullivan, U.S. Pub. Health Rep. Suppl., 1929, No. 78; M. X.Sullivan and D. B. Jones, ibid., No. 82; M. X. Sullivan and W. C. Hew,ibid., No. 86; A., 1930, 1604.G. Denighs, Bull. Pharm. Soc. Bordeaux, 1930, 68, 49, 51; A., 604.53 Idem, ibid., Reprint No. 1450; A., 831.54 F. S. Daft and R.D. Coghill, J . Biol. Chem., 1931, 90, 341; A., 638.5 5 L. Pincusson and E. von Heyden, Biochem. Z., 1931, 234, 484; A.,56 F. Weiss, Apoth.-Ztg., 1930, 45, 724; A., 375.5 7 H. Baggesgaard-Rasmussen and S. A. Schou, Arch. Pharm., 1930, 268,5 8 A. P. Snesarov, J . Chem. Ind. Russia, 1931, 8, 161; A . , 752.5B H. D. Baernstein, J . Biol. Chem., 1930, 89, 124; A., 108.6o R. Machtou, J . Pharm. Chim., 1931, [viii], 13, 329; 4., 639.61 A. Ionescu-Matiu and (Mme.) Popesco, ibid., 14, 54; A., 1079.62 S. Marks and R. S. Morrell, Analyst, 1931, 56, 428; A., 1035; Hupp-63 S . Marks and R. S. Morrell, Analyst, 1931, 56, 508; A., 1149.g4 V. Cuculescu, Bul. Pac. Stiilzte Cernauti, 1928, 2, 143 ; A., 752.829.673; A., 371.mann, Pharm. Ztg., 1931, 76, 113; A., 752208 FOX AND ELLIS:are prescribed ; 65 cuprammonium sulphate precipitates picricacid as a picrate which may be weighed.66 Trinitrotoluene, butnot trinitroxylene, is converted by p-nitrosodimethylaniline inpresence of pyridine and a trace of iodine into the azomethinecompound which is weighed.67 Reduction with titanous chlorideis applied on a micro-scale to various aromatic nitro-compounds.68Examination has been made of the methods of analysing cres01s.~~Physical Methods.There has been a discussion on titration in Wood's light.'OCalcium oxalate is considered unsuitable for nephelometry, 71 whichhas been applied to the determination of sulphates.72Methods involving extinction coefficients have been applied tobenzene in alcohol 73 and to t h i ~ c y a n a t e .~ ~ Photoelectric methodsare used for dilute solutions generally 75 and for certain hydroxy-acids. 76 The copper salts of the amino-acids show characteristicabsorption curves. 77 Partition constants for pairs of fatty acidsbetween ether and water have been ascertained ; 78 camphor affectsthe surface tension of a dilute alcohol solution proportionately. 79An " isopyknoscopic " method can be used for ascertaining theconcentration of solutions of pure compounds. Radiometricmicroanalysis is used in sulphide determinations and oxidimetry. *lAtmospheric ozone is determined by an optical method; s2 the6 5 A. Suchier, 2. anal. Chem., 1931, 85, 434; A., 1318.6 6 M. Franqois and (Mlle.) L. Seguin, Ann. Palsif., 1930, 23, 481 ; A ., 107.67 S. Secareanu, Ber., 1931, 64, [B], 834; A., 752.6 8 S . Maruyama, Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1931, 16, 196;60 P. Dumont, J . Pharm. Belg., 1930, 12, 1, 21, 41, 65, 87; A., 375.70 A. G. Nasini and P. de Cori, Atti I I I Cong. Naz. Chim., 1929, 668; A . ,924.71 A. I. Polinkovski, Trans. State Inst. Test. Building Mat., 1929, No. 27,11; A., 1259.72 Chatron, J. Pharm. Chim., 1931, [viii], 13, 321; A., 586; S. W. Pamand W. D. Staley, I d . Eng. Chem. (Anal.), 1931, 3, 66; A., 451.73 G. Gr6h and E. Faltin, Magyar Chern. Pol., 1930, 36, 156; A., 638.71 C. Urbach, Biochem. Z., 1931, 237, 189; A., 1257.7 5 M. Matsui and T. Noda, J . SOC. Chem. Ind. Japan, 1930, 33, 517; A.,7 6 A. S. Williams, R. H.Muller, and J. B. Nieder!, Mikrochem., 1931, 9,7 7 H. Ley and B. Arends, 2. physiol. Chem., 1930,192, 131 ; A., 1930, 1604.C. 1%. Werkman, Iowa State Coll. J . Sci., 1930, 4, 459; A., 374.79 M. L. Nichols and A. Stubblefield, 2. anal. Chem., 1931,86,30; A., 1318.A. Del Campo, C. Nogareda, and M. G. de Celis, Anal. Pis. Quim., 1931,81 R. Ehrenberg, Mikrochem., Emich Festschr., 1930, 120; A., 1930, 1542.s2 A. I. Duninowski, Compt. rend., 1930, 191, 859; A . , 55.A., 1318.325.269; A., 936.29, 386 ; A., 924ANALYTICAL CHEMISTRY. 209pressure at which phosphorus starts to glow is governed by theproportion of hydrocarbon in the air or oxygen.83 Mixtures maybe analysed by monochromatic transmission.84 A method forreducing the errors of colorimetric determinations is recorded.85X-Ray methods have been applied quantitatively to certainrare-earth mixtures, 86 to copper-silver and -zinc alloys, 87 to certainother binary alloys,88 and qualitatively to distinguish betweenmagnesite and dolomites.89 Spectro-analytical methods are de-scribed for the determination of traces of mercury,w of strontiumin calcium,g1 of traces of nickel and chromium,92 of binary alloys,93of various gases,9* of metals in s0lution,~5 and qualitatively fortraces of impurities in metals ; 96 a means of increasing the accuracyof quantitative emission spectral analysis is indi~ated.~'EZectroEytic.-Small electrodes are described for qualitativemicroelectrolysis.98 Several papers deal with the electro-analyticalseparation of copper.99 Lead is deposited free from antimonyfrom alkaline tartrate solutions under certain conditions.lThe series of polaro-graphic studies with the dropping-mercurycathode have been continued.283 J.Tausz and H. Gorlacher, 2. anal. Chem., 1931, 83, 81; A . , 587.84 M. Barnard and P. MeMichael, I d . Eng. Chem. (Anal.), 1930, 2, 363;8 5 F. F. Hahn and R. Klockmann, 2. angew. Chem., 1930,43,993; A., 54.86 P. Giinther, A. Kotovski, and H. Lehl, 2. anorg. Chem., 1931, 200, 287;H. Terrey and E. G. V. Barrett, J. Physical Chem., 1931, 35, 1156; A.,G. R. Fonda and G. 13. Collins, J. Amer. Chem. SOC., 1931, 53, 113; A.,F. Halla, -Monatsh., 1931, 57, 1 ; A , , 453.W. Gerlach and E..Schweitzer, 2. anorg. Chem., 1931, 195, 255; A., 328.A., 1930, 1541.A., 1261.702.328.91 K.Ruthardt, ibid., p. 15; A., 327.92 A. J. de A. Gouveia, Rev. Chim. pura appl., 1930, 5 , 41; A., 1143.93 G. Guzzoni, Atti 111 Cong. Naz. Chim., 1929, 636; A., 924.94 B. de la Roche, Bull. SOC. chim., 1930, [iv], 47, 1326; A., 185.95 F. Twyman and C. S. Hitchen,Proc. Roy. SOC., 1931, [A], 133,72 ; A., 1260.96 L. h e y , Compt. r e d . , 1930, 191, 1049; A., 187; H. E. Redeker and9 7 G. Scheibe, C. F. Linstrom, and 0. Schoettler, 2. angew. Chem., 1931,g 8 H. J. Brenneis, Mikrochem., 1931, 9, 385; A., 924.gS H. Holemann, 2. anal. Chem., 1930, 81, 161; A . , 57; idem, ibid., 82,273; A., 187; T. L. Kelly and J. J. Molloy, J. Amer. Chem. SOC., 1931, 53,1337; A . , 702; C. Zbinden, Bull. SOC. Chim. biol., 1931, 13, 36; A., 701;N.H. Furman, Ind. Eng. Chem. (Anal.), 1931, 3, 217; A., 701.P. A. Leighton, J. Amer. Chern. SOC., 1930, 52, 4169; A., 1930, 1546.44, 145; A , , 924.E. M. Collin and H. J. S. Sand, Analyst, 1931, 58, 90; A., 588.J. Heyrovskg and V. Nejedlg, Coll. Czech. Chem. Comm., 1931, 3, 126;A., 451; K. Suchy, ibid., p. 364; A., 1025; J. Prajzler, did., p. 406; A.,1261 ; J. Heyrovsk;j, Arhiv Hemiju, 1931, 5, 162; A., 12572 10 FOX AND ELLIS:Potentiometric.-Methods are described for the titration of leadwith ~hromate,~ of silver i ~ d i d e , ~ of silver, cupric, and mercuricions with c~balt~icyanide, of iridium,6 of bivalent platinum,' ofuranium,' of zinc,9 of ferric and dichromate ions with uranoussulphate,lo of ferrocyanide and nitrite mutually,ll of Caro's acidand hydrogen peroxide,l2 of carbonate,13 of phosphoric acid,14of cystine and cysteine,ls of certain drugs l6 and alka1oids,l7 ofpiperidine in mixture with pyridine and its homologues, l8 andof amino-nitrogen.lg The point of inflexion on the titration curveof zinc chloride with sodium hydroxide occurs before two equivalentsof the alkali have been addedm20The value of two solid electrodes in cases involving titrationswith ferrocyanide and with silver nitrate,21 and some factors con-cerned in differential titration 22 have been studied.Conduct0metric.-The titration of sulphate and ofmolybdenum, tungsten, and thallium,24 the influence of smallamounts of carbonic acid on the titration of acids and bases,25R. W. Gelbach and K. G. Compton, Ind. Eng. Chem. (Anal.), 1930, 2,397; A., 1930, 1545.* E. Lange and R. Berger, Z. Elektrochem., 1930, 36, 9SO; A., 186.L. Czaporowski and J. Wierciliski, Rocz. Chem., 1931, 11, 95; A., 588.S. C. Woo and D. M. Yost, J . Amer. Chem. Soc., 1931, 53, 884; A., 590.0. Stelling, Svensk Kem. Tidskr., 1931, 43, 130; A., 814.D. T. Ewing and (Mrs.) M. Wilson, J. Amer. Chem. Soc., 1931, 53,2105 ;A., 927; N. H. Furman and I. C. Schoonover, ibid., p. 2561; A., 1026; M.A. Luyckx, Bull. SOC. chim. Belg., 1931, 40, 269; A., 1026.E. Brennecke, 2. anal. Chem., 1931, 86, 175; A., 1260.lo E. H. Ducloux, Rev. Pac. Cienc. quim., L a Plata, 1930, 7, 11, 97; A.,11 J. V. Romb, Anal. Pis. Quirn., 1930,28, 1045; A., 1930, 1542.l2 E. Muller and Q. Holder, 2. anal. Chern., 1931, 84, 410; A., 1023.l3 A. Ringbom, ibid., p. 161; A., 812.l4 A. Sanfourche, Compt. rend., 1931, 192, 1225; A., 812.l5 K. Yamazaki, J . Biochem. Japan, 1930, 12, 207; A., 374.l6 L. Maricq, Bull. SOC. chim. Belg., 1931, 40, 361; A . , 1318.1 7 Idem, ibid., 39, 496; A., 375; M. L. Holt and L. Kahlenberg, J. Amer.1s A. Travers and Franquin, Compt. rend., 1930, 191, 1340; A., 375.1025.Pharm. ASSOC., 1931, 20, 11; A., 375.J. Roche and (Mme,.) A. Roche, Bull. SOC. Chim. b i d , 1931, 13, 835; A.,1318.20 M. Prytz, 2. anorg. Chem., 1931, 200, 133; A., 1260.2 l J. A. Atanasiu and A. J. Velculesco, 2. anal. Chem., 1931, 85, 120; A.,z2 D. A. MacInnes and I. A. Cowperthwaite, J . Amer. Chem. SOC., 1031, 53,23 I. M. Kolthoff and T. Kameda, Id. Eng. Chem. (Anal.), 1931, 3, 129;24 G. Jander, 2. angew. Chem., 1930, 43, 930; A., 1930, 1548.25 W. Poethke, 2. anal. Chm., 1931, 86, 45; A., 1256.1260.555 ; A., 450.A., 699ANALYTICAL CHEMISTRY. 211and the titration of organic acids and bases in benzene 26 have beenstudied. For binary mixtures of formic, acetic, propionic, andn-butyric acids, the antilog of K x lo3 is a linear function of thecomposition.27 On account of ready oxidation in alkaline solutionpreventing the use of ordinary indicators in the determination ofthe acetyl group in acetylated derivatives of polyhydric phenols,the conductometric method is utilised.28 J. J. Fox.B. A. ELLIS.26 V. K. LaMer and H. C. Domes, J . Amer. Chem. SOC., 1931, 53, 888;27 E. I. Fulmer, E. E. Moore, and R. L. Foster, J . Physical Chem., 1931,28 C. Torres, A. S. Capuchino, and L. Socias, Anal. Pis. Quim., 1930, 28,A., 584.35, 1227; A., 1078.694; A., 1930, 1605

ISSN:0365-6217    

DOI:10.1039/AR9312800179

出版商:RSC    

年代:1931

数据来源: RSC

摘要:

BIOCHEMISTRY.UNQUESTIONABLY the most striking achievements in biochemistryduring the past year are to be seen in the noteworthy advances inour knowledge of the fat-soluble vitamins and of their precursors.In particular it is the pleasing task of the Reporter to review thesteps which have led to the isolation for the first time of a crystallinesubstance which has every claim to be regarded as a vitamin in astate of purity. The culmination of much patient work carried outprincipally in this country, in Germany, and in Holland has resultedin the identification of the antirachitic vitamin D with a crystallineisomeride of ergosterol to which Dr. Bourdillon and his co-workershave given the name of " calciferol."In the section devoted to plant biochemistry particular attentionhas been given this year to matters relating to, or arising from, themineral nutrition of plants.To make this portion of the Report ascomplete as possible, reference has been made to many publicationswhich appeared prior to the year under review, but have not hithertobeen noted in these Reports.Vitamin D and Ergosterol.It will be evident from the review of the position given in theReport of last year,l that the methods and results there describedprovided a reasonable basis for the expectation that the workers inthe Medical Research Council's laboratory would before long havethe pure vitamin in their hands. Events have fully justified thisexpectation. In the course of the year under review there weredescribed, in addition to the crystalline material already mentionedin the Report of last year,2 three other crystalline preparations ofvery high antirachitic potency.The main properties of these aresummarised in Table I.TABLE I.Max. U. V.Preparation. M. p. Rotation. absorption. Analysis.Angus et al. ............... 123-125" [a]546l +260" 270 mp Cz,H,,Oin alcoholin etherm acetoneCNH4,O Reerink and van Wijk 115-117° [a]? +loo" -Windaus .................. 122-123" [a]6461 + 169" 265-270 mp C,,H,,OThe first-mentioned of these preparations, to which the name" calciferol " was first given, was described by T. C . Angus, F. A.1 Ann. Reports, 1930, 27, 277. Ibid., p. 278BIOCHEMISTRY. 213Askew, R. B. Bourdillon, H. M. Bruce, R. K. Callow, C. Fischmam,J.St. L. Philpot, and T. A. Webster.3 It is essentially the crystalhepreparation described last year, obtained in larger quantity and in astate of greater purity by improvements in the technique of pre-paration and isolation. The second preparation is that of E. H.Reerink and A. van Wijk,4 whilst the third was obtained by A.Winda~s.~ All three preparations proved to have approximatelythe same antirachitic activity ranging from 20,000 to 25,000international units 6 per milligram of substance. The absorptionspectra were similar, and all three substances might lay claim to beregarded as isomerides of ergosterol, as will be seen from the analy-tical data quoted. None the less, the speciiic rotations of the threepreparations varied considerably, and it seemed evident that theycould not be regarded as being identical or homogeneous.On theother hand, there was strong presumptive evidence that the anti-rachitic activity of calciferol was an inherent property of the crystalsand was not due to traces of an active contaminant, but the possiblepresence of an inactive impurity could not be excluded. It is to benoted that the distillation method used by Angus et al. for theisolation of the crystalline substance involved the subjection of theirradiation product to temperatures of the order of 150". On theother hand, Windaus obtained his crystalline material with theavoidance of high temperatures. He treated irradiated ergosterol,freed from unchanged sterol, with maleic anhydride in ether at roomProc.Roy. SOC., 1931, B, 108, 340; A., 881.Biochem. J., 1931, 25, 1001 ; A., 1197.Proc. Roy. Xoc., 1931, B, 108, 568; A., 1098.The international unit of antirachitic potency was defined at the Leagueof Nations Conference in June, 1931. It is the " vitamin D activity of 1 mg.of the International Standard Solution of irradiated ergosterol." The standardsolution is made by dissolving a particular sample of irradiated ergosterol inolive-oil, so that 1 gram of the oil contains 0.1 milligram of the irradiatedmaterial. 1 Milligram of the oily solution therefore contains 1/10,000 milli-gram of the mixed products of irradiation, and this, by definition, contains1 international unit of vitamin D activity. It was fixed a t this value, sinceexperiments showed that 1 unit per diem, given to a rachitic rat, was aboutthe dose required to produce healing in ten days, the total amount adminis-tered being, therefore, ten units.The international unit has the same valueas the unit previously adopted by the Medical Research Council, which bodyhas been mainly responsible for the adoption of the present InternationalStandard. It is probable that in the near future the unit will be more con-veniently re-defhed in terms of pure calciferol. I f this is done, it is likelyto be on a strictly comparative basis so that the unit will remain unchangedin value, but will be referred to a given weight of a standard sample of purecalciferol.The information embodied in this footnote has been given to the Reporterby Sir H.H. Dele, C.B.E., F.R.S., of the Medical Research Council, London214 POLLARD AND PRYDE:temperature. The portions which had reacted with the anhydridewere then removed with dilute potash solution, and the .remainingproduct readily crystallised on evaporation of the solvent. Recrys-tallisation was easily effected from various solvents. The Reerinkand van Wijk preparation was obtained by methods permitting ofthe irradiation and all subsequent extraction and crystallisationprocedures being carried out in a vacuum at the ordinary tem-perature.With these facts in mind the Medical Research Council workersturned their attention to the possible presence in their crystallinematerial of the products of thermal decomposition of the irradiationproducts.They were able to show that, when the active crystallinematerial was heated a t 180", it was transformed into an inactivecrystalline isomeride of ergosterol which had a remarkably highdextrorotation, and to which they gave the name " pyrocalciferol."It therefore seemed highly probable that calciferol obtained bydistillation might be contaminated with-pyrocalciferol and that suchcontamination might well account for its high dextrorotation.A considerable advance was foreshadowed when R. K. Callow 7referred to the preparation of a crystalline ester-the 3 : 5-dinitro-benzoate-of calciferol from which the active crystalline materialcould be regenerated by hydrolysis. Evidence was obtained of theseparation of the ester into two components, and it was suggested,that the distilled product was a mixture, or a molecular compound,of pyrocalciferol and a substance with a higher antirachitic activibythan any product obtained up to that time.F. A. Askew, H. M.Bruce, R. K. Callow, J. St. L. Philpot, and T. A. Websters laterpublished results fully confirming this hypothesis. The activecrystalline material was treated with 3 : 5-dinitrobenzoyl chloridein pyridine, and the product separated by fractional crystallisationinto two esters, both of which were repeatedly recrystallised.Calciferyl3 : 5-dinitrobenzoateY m. p. 147-149", yields on hydrolysiscalciferol, m. p. 114-5-117", having [a]52:i1 + 122~5"~ [a]:' + 102-5"in alcohol, and + 98-5", [a]5' + 81" in acetone. Its solutionin alcohol has an intense absorption band with a maximum a t265 mp and it possesses an antirachitic activity of 40,500 inter-national units per milligram, which is approximately twice that ofany previous preparation containing vitamin D.Pyrocalciferyl3 : 5-dinitrobenzoate, m. p. 167-5-169.5", on hydrolysis yields7 " Chemistry a t the Centenary Meeting of the British Association," Hefferand Son, Cambridge, 1932. (The Reporter is indebted to Mr. J. DavidsonPratt of the Association of British Chemical Manufacturers for a copy of theproofs of this forthcoming publication.)Nature, 1931, 128, 758BIOCHEMISTRY. 215pyrocalciferol, m. p. 93-95", having [a]:'& + 624", [a%* + 502"in alcohol. The maximum absorption is at 284 mp. Pyrocalciferolhas no antirachitic activity.Both calciferol and pyrocalciferol havebeen shown on analysis to have the same empirical formula asergosterol.In addition to pyrocalciferol there is present in the crystallinematerial obtained by Dr. Bourdillon and his co-workers9 anotherirradiation product, which has been called " sterol X." Thissubstance has been isolated in a crystalline condition (see Table 11).Its colour reactions with trichloroacetic acid and with mercuricacetate in nitric acidlo indicate the presence of a AlZ2 (or A1:13)-linkage, which is also present in ergosterol but not in calciferol orpyrocalciferol. As in the case of the two last-mentioned sterols," sterol X " forms a crystalline 3 : 5-dinitrobenzoate by means ofwhich it has been separated from the corresponding ester of calci-ferol.The supposition that calciferol is a direct product of the irradiationof ergosterol is confirmed by the isolation of its 3 : 5-dinitrobenzoatefrom the undistilled, crude irradiation product.The ester and theparent calciferol thus obtained are identical with those obtained fromthe distilled material, and the yield is such that the greater part ofthe antirachitic activity of the crude resin can be accounted for bythe calciferol actually isolated as theester. Sterol X is also foundin the undistilled irradiation product.It will be realised from the foregoing that the substance firstprovisionally called " calciferol " proved to be a mixture, or solidsolution, of two molecular compounds of true calciferol (or purevitamin D) with pyrocalciferol and with sterol X.None the lessthe name calciferol is retained (at least by the British workers) for thevitamin, since it is pointed out 11 that the term vitamin D is incon-venient when referring to esters and other derivatives of the com-pound, and the adoption of a new name would tend to confusion.While these developments were occurring in this country a paperby A. Windaus, A. Luttringhaus, and M. Deppe12 carried theGerman work a stage further. The crystalline product alreadydescribed was further characterised and termed " vitamin D1."In an addendum to this paper by 0. Linsert there wasmentioned aF. A. Askew, R. B. Bourdillon, H. M. Bruce, R. K. Callow, J. St. L. Philpot,and T. A. Webster, Proc. Roy.SOC., 1932, B, 109, 488. (The Reporter isindebted t o Sir H. H. Dale, C.B.E., F.R.S., Director-in-Chief of The MedicalResearch Council's laboratory, for a proof copy of this paper.)lo 0. Rosenheim, Biochem. J., 1929, 23, 47; A., 1929, 359; 0. Rosenheimand R. K. Callow, ibid., 1931, 25, 74; A., 529.l1 F. A. Askew, R. B. Bourdillon, et al., Zoc. cit.12 Annalen, 1931, 489, 262; A., 1464216 POLLARD AND PRYDE:second crystalline substance which was referred to as (( vitamin D2.”Its quoted optical rotation and melting point were very similar tothose of calciferol, sufficiently so to suggest identity to the Britishworkers. At first Windaus regarded D, and D, as independentantirachitic substances of approximately equal activity. Later, asa result of interchange of materials and results with the Britishworkers, Windaus and his colleagues, making use of the dinitro-b e ~ o y l esters, were able to fractionate D, into D, and an inactivesubstance which is identical with sterol X, and for which the Germanworkers have suggested the name “ lumisterin.” 13 It has furtherbeen established that the antirachitic activity of D, is twice that ofthe D, crystalline material, and therefore equal to that of purecalciferol. There can therefore remain little doubt that the calciferolof the British workers and the vitamin D, of the German workers areidentical and approximately pure specimens of the antirachiticvitamin.l* In Table I1 a summary is given of the salient proper-ties of the known transformation products and of their derivativesarising from ergosterol in the course of the formation of vitamin D.There remains to be considered the crystalline material isolatedby Reerink and van Wijk.The experiments of these workers ledthem to the conclusion that their active crystalline material (whichthey called substance L) was formed in one step from ergosterol whenthe latter was subjected to radiations not shorter than 284mp inwave-length. This is inferred from the fact that the rotation of theergosterol during irradiation shows a linear dependence on its degreeof transformation as deduced from a determination of the unchangedergosterol by the digitonin method. Whilst the transformation ofergosterol into vitamin D must be regarded as a simple uni-molecular rearrangement, it is now quite clear that other trans-formation products are formed concurrently, and it seems veryprobable that substance L is a mixture of calciferol and one or moreof the inactive irradiation products.Criteria of Purity of CaZciferoL-In any other class of chemicalcompounds the evidence of purity and homogeneity discussed in theforegoing paragraphs would be accepted as convincing.In the sterolgroup, however, the occurrence of association compounds and ofsolid solutions is very frequent, and this renders difficult the attain-ment of certainty regarding the purity of a new compound. It isat the present time impossible to secure complete proof that theactivity of calciferol is not due to small quantities of an intensely13 A.Liittringhaus, Chem.-Ztg., 1931, 55, 936. Presumably the Englishl4 A. Windaus and A. Luttringhaus, 2. physiol. Chem., 1931,203, 75 (adden-equivalent “ lumisterol ” will be adopted in this country.-J. P.dum); F. A. Askew, R. B. Bourdillon, et d., Zoc. citTABLE 11.Properties of Calciferol, and Allied Compounds, andMeltingSubstance. point.Sterols.1. Purified calciferol ............ 114.5-117'2. Vitamin D, ( a ) ............... 114 -1153. Vitamin D, ( c ) ............... 124 -1259 9 (b) ............... 110*5-113*5, 9 ( d ) 124 -127 ...............[a]%. -- Ethylalcohol. Acetone.f122.5" + 98.5"+ 120 - + 174 - + 176 -- -- 4. Pyrocalciferol ............... 93 - 95 +6245. Sterol X ........................116.5-118.5 +220ducts (e) ..................... 123 -125 +260ducts (f) to to-6. Crystalline distillation pro--Crystalline distillation pro- 119 -123 + 220 -7. Calciferol-pyrocalciferol, 120 -122.5 + 374 I121 -125 3251 : 1 mixture.3 : 6-Dinitrobenzoates. In benzene.1. Of calciferol .................. 147 -149 +69.5 + 1052. Of vitamin D, ( 9 ) ............ 145 -147 +70.5 +105.53. Of pyrocalciferol ............ 167-5-169.5 + 2604. Of sterol X ..................... ,139.6-141.5 + 24 -( a ) Prepared by Windaus, Luttringhaus, and Deppe (Zoc. cit.).( b ) Prepared by Windaus (not quite pure).( c ) Prepared by Askew, Bourdillon, et aZ. (Eoc. cit.).( d ) Prepared by Windaus.[a]$'. - E thy1alcohol. Acetone.+l02.5" + - ++ 141 - ++ 502+ 176-(e)(f)( 9 218 POLLARD AND PRYDE:active contaminant, but this is rendered most improbable by therelative ease with which closely allied sterols (pyrocalciferol andsterol X) can be separated from it without perceptible antirachiticactivity.Moreover, the different preparations of calciferol -showvery little variation in physical properties, whether prepared fromthe irradiation products of ergosterol by direct esterification, or afterremoval of contaminants, or by distillation and subsequent esteri-fication. Due allowance being made for the errors in the biologicalmethod of assay, a reasonable constancy in the antirachitic activitymay also be claimed. Finally, calciferol yields crystalline esterswhich, on recrystallisation and hydrolysis, give back the originalsterol with unchanged physical and biological properties.It is to be anticipated that the nature of the active group orgroups in vitamin D should soon be elucidated. The results alreadyoutlined point to the presence of three double bonds, as in ergosterol,but one a t least of these bonds is in apositiondifferent from that ofthe parent sterol.Windaus l5 accepts as proved the view that theantirachitic activity is specifically associated with the presence ofthe hydroxyl group. I n support of this he points out that, if thehighly active crude irradiation product is carefully treated withphenyl isocyanate, a derivative completely lacking in antirachiticactivity is obtained. But if this derivative is warmed with alcoholicpotash, it is reconverted into a highly active material.Altern-atively, ergosterol phenylurethane may be irradiated. It is foundto undergo some change, but it does not acquire antirachitic activity.If, however, the irradiation product is hydrolysed, a highly activesubstance is produced.Toxic E#ects of Excess of CalciferoZ.--In recent years many observ-ations have been made concerning the toxic effects of excessiveadministration of irradiated ergosterol and of other preparationscontaining vitamin D. Various aspects of the resulting patho-logical manifestations have been attributed to the vitamin itself andto its accompanying contaminants, for instance, the “ calcinosis ”factor.16 I n view of the advances of the past year there is littledoubt that a clearer insight into such problems will be gained, andif the calcinosis factor, and similar hypothetical substances, are realentities their differentiation from the true vitamin should be rela-tively simple.I n the meantime attention is directed to somepreliminary results recorded by Askew et a1.l’ Tests carried outon mice show that the minimal toxic dose of calciferol is of the order0.1 mg., of crude calciferol8-2 mg., and of a preparation of Windaus’sD, 0.2 mg. The ratio of the toxic dose (in mice) to the curative15 L O C . cit.17 F. A. Askew, R. B. Bourdillon, et al., Zoc. cit.l6 Ann. Reports, 1930, 27, 279BIOCHEMISTRY. 219dose (in rats) is therefore about 400011. These results are notclaimed as final, but they support the view that the toxicity is aninherent property of the pure vitamin and is not due to a contamin-ant.A. Windaus, P. Busse, and G. Weidlichls and L. J. Harrisand J. R. M. Innes19 have arrived a t a similar conclusion. Thelast-mentioned workers have furnished evidence which substantiatesthe theory that vitamin D exerts its toxic action by raising theblood calcium or phosphate. It is shown that this increase isassociated with an increased net absorption from the gut, which isof special importance in hypervitaminosis with diets rich in calcium,but also that the shaft of the bone may provide an important addi-tional source in certain circumstances, for instance, on lowcalcium diets and with a larger excess of vitamin D.Vitamin A and Carotene.In the Reports for the past two years 2O there have been reviewedthe results of numerous investigations of the possible relationshipof the hydrocarbon carotene to vitamin A.Interest in this field hascontinued to develop, and the newly acquired biological interest ofthe hydrocarbon has stimulated the organic chemist t o provide muchinteresting and welcome information concerning its chemical nature.On this purely chemical side the investigations of Professors P.Karrer and R. Kuhn are especially noteworthy.The Carotenoids.-Karrer states that there are ten basic types ofcarotenoid pigmenk21 These are found in plants and in animalsboth in the free form and, in some cases, as esters. Three carotenoidsare carboxylic acids, namely, crocetin, CgOH24O4, bixin, C2,H,O4,and azaffrin, and these alone are stable in the presence of oxygen.Three carotenoids are hydrocarbons, namely, lycopene, C4,H5,, andthe two isomeric a- and @-forms of carotene, c40H56.The remainingmembers of the group contain two or more hydroxyl groups. Theseare the a- and @-xanthophylls, C40H,,0,, zeaxanthin, C,H5,02,violaxanthin, C40H5604, and capsanthin, C34H4803 or C3,H,03.Carotenes.-Of these natural pigments, only the a- and P-carotenesare capable of restoring growth in animals which have been deprivedof vitamin A. Partial reduction of a- and P-carotenes yields a- and@-dihydrocarotenes,22 which have not yet been crystallised. Theseboth contain the p-ionone ring with its double bond. It has beenl8 2.physiol. Chem., 1931, 202,246.19 Biochem:J., 1931, 25, 367; A., 659.2O Ann. Reports, 1929, 28, 245; 1930, 27, 276.21 “ Chemistry at the Centenary Meeting of the British Association,” Heffer22 J. H. C. Smith, J. Biol. Chem., 1931, 90,597; A., 491.and Son, Cambridge, 1932220 POLLBRD AND PRYDE:claimed that these dihydrocarotenes can serve as a source of vitaminA,23 but J. C. Drummond states that this is not so when precau-tions are taken to free the hydrogenated product from all traces ofunchanged carotene. It has likewise been claimed 25 that di-iodo-carotene is biologically active, but this appears to be so only in as faras carotene is regenerated from it in the body. Kuhn 26 and Karrer 27and their respective co-workers have made a study of the separationof the a- and P-carotenes.Kuhn states that a-carotene melts a t175-176" and has [a]cd + 365" in benzene, whilst the p-form meltsa t 181-182" and is optically inactive. The ratio of a-caroteneto @-carotene varies considerably in different plants and manycarotenes are found to consist exclusively of the p-form. In TableI11 there are reproduced some of Kuhn's figures regarding therotatory power and a-carotene content of different preparations.TABLE 111.MateriaI. r a]% a-Carotene, yo.Palm oil .......................................... + 120-170" 30-50Horse chestnut leaves ........................ 90 25Carrots .......................................... 30-70 10-20Sorb apples .................................... 50 15Stinging nettlesGrassSpinachCapsicum fruitsThe carotene prepared from the corpora Zutea of cows consistsexclusively of the p-form, the explanation for which is found in theoccurrence of the p-form alone in grass.A mutual interconversionof the ct- and p-forms does not seem to occur in vivo. A third form ofthe hydrocarbon, called isocarotene,28 is known, but this does notoccur as a natural product, nor does it give rise to vitamin A in theanimal body.29 It is formed when @-carotene is precipitated withan excess of iodine and the resulting iodide decomposed with sodiumthiosulphate or mercury. It contains 13 double bonds like theopen-chain lycopene, that is, two more than natural carotene.The formula of carotene has already been discussed in these23 P.Karrer, H. von Euler, H. Hellstrorn, and M. Rydbom, Svensk Kern.Tidslcr., 1931,43,105 ; H. von Euler, P. Karrer, H. Hellstrom, and M. Rydbom,Helv. Chim. Acta, 1931, 14, 839; A., 1097.24 " Chemistry at the Centenary Meeting of the British Association," Hefferand Son, Cambridge, 1932.25 Ann. Reports, 1929, 26, 246.26 R. Kuhn and E. Lederer, Naturwiss., 1931, 19, 306; Ber., 1931, 64, [B],27 P. Karrer, A. Helfenstein, H. Wehrli, B. Pieper, and R. Morf, Helv. Chim.28 R. Kuhn and E. Lederer, Zoc. cit.29 R. Kuhn and R. Brockmann, Ber., 1931,64, [B], 1859; A., 1097............................... 0 0 11349.Acta, 1931, 14, 614; A., 733BIOCHEMISTRY. 221Reports 30 and it will suffice. to state here that the formula originallysuggested is retained for a-carotene, whilst two alternative ringstructures, each with an asymmetric carbon atom, are tentativelyadvanced for a-carotene, the optically active form :-Me\ /Me Me\ /Me/c\ --CH=Q QH2 .. . * -CH,*yH 7H2MeC CH,/c\ . . . .MeCH CH,\ / CH\ /CH2i"; /A \Carotene and Vitamin A .-The structural relationship of caroteneto vitamin A remains to be elucidated. H. R. Bruins, J. Overhoff,and L. K. Wolff 31 have measured the diffusion constants of caroteneand vitamin A in xylene and from these the ratio of the molecularweights of the two substances has been calculated. A molecularweight of about 330 is deduced for the vitamin. The molecularweight of carotene is 536, so that a simple direct relationship betweenthe hydrocarbon and the vitamin appears to be excluded.P.Karrer, R. Rlorf, and K. SchOpp,3, from the ozonisation of the purestavailable preparations of vitamin A, have obtained geronic acid,which is also obtained by a similar treatment of carotene :Me\ /MeA CHz fi--CH=Me, ,MeCF/HzbO*OHGeronic acid.The inference is that vitamin A contains in its molecule the samering as p-ionone and p-~arotene.~~ A substance of the followingstructure, which might be obtained by oxidative disruption of amolecule of carotene, has been tentatively discussed by Karrer as aworking hypothesis in considering the structure of the vitamin :303233492 ;Me\ ,MeQH2 /5 E-[-CH=CH- r =CH-],-CH-CH*CH,*OHCH2 CMe\ /CH2Ann. Reports, 1930, 27, 167.Helv.Chim. Acta, 1931, 14, 1036; A., 1463.See also R. Pummerer, L. Rebrnann, and W. Reindel, Ber., 1931, 64, [B],s1 Biochem. J., 1931, 25, 430; A., 771.A., 491222 POLLARD AND PRYDE:As has already been stated, both the a- and the p-form of caroteneare biologically active. H. von Euler 34 finds that the p-form showssome advantage in this respect over the a-form, but it is clear thatboth forms show a biological activity which’ must be independentof the asymmetric carbon atom. Certain results quoted by R.Kuhn 35 show that the p-form has a decided advantage when smalldoses are given and when the feeding period is short. With largeramounts of the carotenes and longer feeding periods the differencebecomes smaller, but does not disappear, as will be seen from theresults given in Table IV.There is general agreement that the transformation of caroteneinto the vitamin takes place in the liver, although von Euler doesnot exclude the possible participation of the bone marrow in theprocess.Indeed, H. S. Olcott and D. C. McCann36 claim to haveTABLE IV.NoMg. Carotene . of rats. per day.8 0.45 a7 1.00 a8 1.00 a6 0.45 /38 1.00 /38 1.00 /3Feeding period indays.6121961219Blue units per g.liver using SbC1,test (av. values).819029080400825effected the transformation in uitro by incubating the hydrocarbonwith fresh liver tissue or with an aqueous extract of liver. Theagent responsible for the change is destroyed by heat and is thereforeregarded as an enzyme, to which the name carotenase is provisionallyassigned.H. von Euler,37 on the other hand, has not been able t oobtain clear evidence of such a transformation in uitro, and 13.Ahmad 38 states that it does not occur.T. Moore39 was one of the first workers in the vitamin field toobtain direct evidence of the accumulation of vitamin A in the liversof animals fed on carotene. Moore40 now finds that the concen-tration of the vitamin in the “ storage ” fats of the body as a resultof such feeding is only about 1/100,000 that of the concentration inthe liver, whilst other tissues give very weak or negative reactions34 H. von Euler, P. Karrer, H. Hellstrom, and M. Rydbom, Zoc. cit.35 “ Chemistry a t the Centenary Meeting of the British Association,” Heffer36 J.Biol. Chem., 1931, 94, 185.37 “ Chemistry at the Centenary Meeting of the British Association,” HefferBiochem. J., 1931, 25, 1195; A., 1196.39 Ann. Reports, 1929, 26, 247; 1930, 27, 276.40 Biochem. J., 1931, 25, 275; A., 529.and Son, Cambridge, 1932.and Son, Cambridge, 1932BIOCHEMISTRY. 223for the vitamin (von Euler and his co-workers state that bonemarrow is a rich source of the vitamin). In another communicationMoore41 points out that the. vitamin A reserves of the averagemammal per gram of liver tissue are of much the same order as thoseof the average fish, the superiority of the extracted mammal-liveroil being largely due to the much smaller amount of fat present.The use of the mammal, however, affords the very great advantagethat the diet can be arranged so as to ensure that the vitamin Acontent of the liver will approach its maximum.A suitable animal,such as a rat or a pig, may be “ fattened up ” on a diet rich incarotene or preformed vitamin A and so used as a “ factory ” for theconcentration of the vitamin. Moore’s experiments along theselines, on animals fed with red palm oil, have yielded highly con-centrated preparations of the vitamin with a minimal daily rat doseof 0-001 mg. The degree of concentration attained in these experi-ments will be appreciated from Table V. In this the “ blue units ”quoted, in reference to the antimony trichloride colour test, are notnecessarily the same as those used by other workers. Thus theTABLE V.Blue units Approx.minimalMaterial. per mg. rat dose (mg.).Butter fat ............................................. 0.02 20Cod-liver oil .......................................... 1 1Jersey cow-liver oil ................................. 100 -Cod-liver oil concentrates ........................ 400 0.005Liver oil of rat fed on Red Palm oil ............Concentrate from liver oil of rats fed withR.P.O. ............................................. 2000 0.00 1600 -Concentrate from pig fed with R.P.O. ......... 2600 -figure 2,600 blue units per mg. corresponds to a blue value of 40,000calculated on the cod-liver oil scale of Drummond and Hilditch.Moore points out that, as far as can be judged, the biological activityof the best concentrates is not more than 2 or 3 times that of carotene,and that this slight superiority might be visualised as being due tothe inefficient conversion of the extremely unstable carotene, orpossibly to the cutting down of the molecule during conversion.The latter possibility accords with the views of Karrer42 and ofBruins, OverhoB, and Wolff 43 already discussed.Spectrographic Behaviour of Vitamin A .-In previous Reportsreference has been made to the spectrographic test for vitamin Aintroduced by R.A. Morton and I. M. H e i l b r ~ n . ~ ~ These investig-41 “ Chemistry at the Centenary Meeting of the British Association,” Heffer42 L O C . cit. 43 L O C . cit.44 Ann. Reports, 1928, 25, 268; 1929, 26, 248.and Son, Cambridge, 1932224 POLLARD AND PRYDE:ators, together with their collab0rators,4~ have made a systematicstudy of materials containing vitamin A with respect to the antimonytrichloride colour reaction and the ultra-violet absorption spectrum.It must be borne in mind that the band at 620 mp, observed in thecolour test on concentrates, is shifted to 604-608 mp in the presenceof the unsaturated bodies existing in the unfractionated liver oils.There is also a band at 583 mp which can be similarly displaced asfar as 565 mp.In most oils this band is near 572 mp but it is almostcompletely masked by the 608 mp maximum. Some oils are encoun-tered in which the 572mp band predominates. The main con-clusions arrived a t in the above-mentioned investigations have beensummarised by Morton and Heilbron 46 as follows : (1) The parallel-ism between the intensity of the 606 mp band of the colour test andthe intensity of the 328 mp band of the spectrogra,phic test breaksdown so seriously in extreme cases as to render it improbable thatthe 606 m p chromogen is vitamin A.(2) The 572 mp chromogenand the substance responsible for the 328mp band are probablyidentical. (3) The blue colour obtained with rich oils and con-centrates is often far deeper than it ought to be on the basis ofcorrelation between the colour and the ultra-violet absorption.This is due to an increase in the 620 mp chromogenic power, whichmay be due to a removal of inhibitors or to a real increase in thechromogen content on saponification. The relationship betweenthis chromogen and vitamin A is obscure.(4) Many oils are encoun-tered in which the blue colour is developed much more strongly ifthe oil has been allowed to stand for a few weeks, or has otherwisebeen subjected to oxidation processes. I n such cases the 328 mpband does not show a similar increase.A statistical analysis 47 of all the data accumulated by biological,chemical, and spectrographic investigation of ten oils and threeconcentrates is regarded by Morton and Heilbron 48 as confirmingbeyond all reasonable doubt the claim of the 328mp band to beregarded as a direct property of vitamin A. Since the 583 mp bandof the colour test runs very closely parallel with the 328 mp bandit too must be accepted as a property of the vitamin. On the other45 R.A. Morton, I. M. Heilbron, and A. Thompson, Biochem. J., 1931, 25,20; A., 529; J. A. Lovern, R. H. Creed, and R. -4. Morton, ibid., p. 1341 ; A.,1195; A. E. Gillam and R. A. Morton, ibid., p. 1346; A., 1195; I. M. Heil-bron, A. E. Gillam, and R. A. Morton, ibid., p. 1352; A., 1195; J. A. Lovernand R. A. Morton, ibid., p. 1336; A., 1196.4 6 “ Chemistry at the Centenary Meeting of the British Association,” Hefferand Son, Cambridge, 1932.47 (Miss) K. H. Coward, F. J. Dyer, R. A. Morton, and J. H. Gaddum,Biochem. J., 1931, 25, 1102; -4., 1196.48 L O C . citBIOCHEMISTRY. 225hand, there is little doubt that fish liver oils contain two chromogensactive in the antimony trichloride test.Enzymes.J. B. S. Haldane 49 has published an interesting theoreticaltreatment of the molecular statistics of an enzyme action.K.Zeile and H. Hellstrom 5O have found that horse-liver catalase is aniron-porphyrin compound with a spectrum resembling that ofalkaline haematin, and that its amount, reckoned in milligrams ofcombined iron, can be measured photometrically with great accuracyby converting it into pyridine-haemochromogen. The assumptionis made that each molecule of liver catalase contains only one atomof iron, and Haldane's mathematical treatment of the data of Zeileand Hellstrom leads him to the deduction that a molecule of catalaseat 0" catalyses the destruction of about 2 x 105 hydrogen peroxidemolecules per second. The mean life of the active catalase-hydrogenperoxide molecule is calculated to be about lo-' second and thevelocity constant for the union of catalase and hydrogen peroxideexceeds 7 x lo6.These values are compared with similar dataderived from other enzymes and from haemoglobin. In concludingthis remarkably interesting study, Haldane points out that, althoughenzymes in the cell are in general acting neither a t their optimaltemperature, p H , nor substrate concentration, it would seem fromthe examples discussed that an enzyme molecule must commonlytransform 100 or more substrate molecules per second. As a veryactive cell, such as baker's yeast, metabolises about 10-6 of a gram-molecule of oxygen per gram dry weight per second, we can get someidea of the possible complexity of the transformation undergone init.If 5% of the dry weight of the cell consists of enzymes of anaverage molecular weight of 50,000, then 1 gram dry weight containsgram-molecule of such enzymes, and less than 1% of this wouldbe required for any particular process, for example, the activationof oxygen. I n other words, the average atom, on its metabolicpath through the cell, may be dealt with by more than 100 catalystsin succession.Crystdline Urease.-An investigation of the chemical nature ofcrystalline urease has been published by E. Waldschmidt-Leitz andF. Steigerwaldt,51 who have used the preparations first described byJ. B. Sumner.52 J. B. Sumner and K. Myrback 53 found it impossible4g Proc. Roy. SOC., 1931, B, 108, 559; A., 1089.Go 2. physiol. Chem., 1930,192, 171; A., 123.51 Ibid., 1931, 195, 260; A., 521.52 J .BioZ. Chem., 1926, 69,435; 70, 97; A., 1926, 1061, 1176.53 2. physioC. Chem., 1930,189,218; A., 1930, 1217.REP.-VOL. XXVIII. 226 POILARD AND PRYDEto decide whether the purest crystalline urease obtainable consistedentirely of the enzyme, but found such urease to be as pure as thebest invertase and to be readily prepared from crude material witha 700- to 800-fold increase in activity. Waldschmidt-Leitz andSteigerwaldt now find that, contrary to the statement of H. Ta~ber,~*the crystalline material, which is of globulin character (confirmingJ. B. Sumner and D. B. Hand 55), does not lose its activity when it issubjected to the action of trypsin and other proteolytic enzymes,although the globulin is hydrolysed.If, then, the crystallineglobulin is not simply a carrier of the active urease, the suppositionthat the crystalline material is itself the enzyme is not warranted,since its breakdown products seem to retain the enzymic activity.Sumner has undoubtedly obtained highly active urease preparationsin a crystalline form, but it is considered possible that the enzymemay be obtained free from admixed protein or protein-breakdownproducts.Crystalline Pepsin and Trypsin.-J. H. Northrop 56 has describedcrystalline preparations of high peptic activity. These are proteinin nature with an estimated molecular weight of 33,000 to 40,000.The nitrogen content, optical rotation, and proteolytic activity wereconstant for six different preparations and remained unchangedthroughout seven recrystallisations.Data from solubility determin-ations in different salt solutions, the rate of inactivation by heat andalkali, and the determination of the diffusion coefficient suggest thatthe crystalline material is a pure substance, although the possibilitythat it is a solid solution cannot be excluded. The inactivation a tpH 10.5 and its reversal yield an active material possessing the samephysical characteristics as the original material, which affordsfurther evidence that the proteolytic activity is a property of themolecule itself. P. A. Levene and J . H. Helberger 57 find that afterfive recrystallisations the pepsin contains only 3.3% of its totalnitrogen as basic nitrogen.J. H.Northrop and M. Kunitz 58 have prepared from commercialsamples of trypsin a crystalline protein which can digest casein andgelatin in neutral solution.Enzymes and Dyes.-The a f i t y which certain dyes show towardsenzymes has already been made the basis of a most useful method forpurifying pepsin.59 It seems that a study of the interactions of dyes54 J . Biol. Chem., 1930, 87, 626; A . , 1930, 1217.66 J . Amer. Chem. SOC., 1929, 51, 1255; A., 1929, 723.6 6 J . Gen. Physiol., 1930, 13, 739, 767; 1931, 14, 713; A., 1930, 1317;57 Science, 1931, 73, 494; A,,, 984.68 Ibid., p. 262; A., 655.1931, 1090.Ann. Reports, 1928, $3, 244227 BIOCHEMISTRY.and enzymes may help in other ways to elucidate the structure andmode of action of the latter. The fact that certain dyes havespecific toxic actions on enzymes, and on the catalytic activities oftissues, has been utilised by J.H. Quastel and A. H. M. Wheatleyin an investigation of the oxidation of a number of substrates byB. wli. have observed that undercertain conditions substances of the indicator type (phenolphthaleinand bromothymol-blue) inhibit the hydrolysis of methyl butyrateby liver esterases. In Table VI are given some of the figuresE. Bamann and M. SchmellerTABLE VI.Nature ofDye (1 /5000). dye. Glucose.Malachite green ... Basic 100Brilliant green . . . . . . . . 68Methyl violet 6B . . . . . 100Crystal violet 9 9 97Methylene blue . . . . . . . . 67Auramine .............. 93Acrifiavine .............. 100Neutral red ...........92Chrysoidine ........... 95Pyronine .............. 39S af ranin e .............. 98Bismarck brown ... 0Acid green .............. 0Soluble blue ........... 0Water blue ......... ,, 0Orange G .............. 0Crystal scarlet 9 9 Congo red .............. 0Benzopurpurine . . . . . 0......Acid fuchsine ...... Azid 0...... 1Lactate.9266889133879572342086401708401531suc-cinate.72674653756145371962282357271022Formate.71468692286468504417622700901416022obtained by Quastel and Wheatley for the percentage inhibition bydyes of oxygen uptakes by B. coli in the presence of various substratesat p H 7.4 and 37".The most important fact demonstrated by these results is thatall the highly toxic dyes are basic, whilst the acid dyes have little orno action at the concentration and p H employed.This leads to theconclusion that the dehydrogenases responsible for the activationof glucose, lactate, succinate and formate are essentially acidic incharacter. An exception is observed in the case of Bismarck brown,a tetrazo-dye which is basic, unlike the other two tetrazo-dyes(Congo red and benzopurpurine) included in the table. It is there-fore apparent that, although basicity of the dye plays an importantpart in determining its combination with dehydrogenase, this is notthe only factor involved; the structure of the dye molecule is alsoconcerned. The action of dyes on the oxidation of succinate by80 Biochern.J., 1931, 25, 629; A., 765.81 2. phg8iol. Chem., 1931,194, 1; A,, 392228 POLLARJ) AND PRYDE:muscle tissue proved to be similar to that found with B. coli, but onthe other hand dyes were without inhibitory action on the oxidationof succinate by brain tissue.Selecting a particular enzyme of wide biological distribution,J. H. Quastel 62 has observed the action of dyes on fumarase, bothin cell-free preparations and in the intact cell. Here a muchgreater specificity of behaviour of the dyes towards the enzyme isobserved. Thus both basic and acidic dyes are toxic; among theacid dyes those of the Congo red series and of the triphenylmethaneseries are toxic, the former being the more effective.Congo red istoxic at a concentration of 1.2 x lo-* M . Trypan-blue and trypan-red are likewise toxic. The enzyme present in the intact cell doesnot always show the same behaviour towards a given dye as when it ispresent in a cell-free extract. This difference is ascribed to thepermeability of the cell membrane and is illustrated by the resultsquoted in Table VII. From this it would appear that B. coli isalmost freely permeable to members of the triphenylmethane series,whereas it is resistant to Congo red and toluidine blue.TABLE VII.Comparison of Percentage Inhibitions effected by Dyes on Fumarasein the Cell Extract and in the Intact Cell (B. coli).Dyes (1 /5000). Intact cell. Cell extract.Congo red ....................................... 59 97Methyl violet ................................. 88 82Water blue ....................................66 57Toluidine blue ................................. 56 90It is not to be supposed that Congo red and trypan-blue aregeneral enzymic poisons; thus neither has a toxic action on urease.There must be some close relation between the structure of fumaraseNH2R + CO (NHR),First s-carbamide derivative.NH,*C6H4*CO*NHR + CO(NH*C613[,*CO*NHR)2m-Aminobenzoyl derivative. Second s-carbamide derivative..1.1\ NH2*C6H, *CO*NH*C,H,*CO*NHRm’-Aminobenzoyl-m-amino-benzoyl derivative.CO(NR*C,H,*CO*NH*C,H,.CO*NHR),Third s-carbamide derivative.and that of the Congo red series of dyes. This consideration ledQuastel 63 to test the action on fumarase of other trypanocidal6* Biochem.J., 1931, 25, 898; A., 983. 68 Ibid., p. 1121; A., 1188BIOCHEMISTRY. 229agents, not belonging to the Congo red series. The well-knomtrypanocide Bayer 205 was found to be toxic, but the main interestin this stage of the investigation lies in the actions of six naphthyl-aminedisulphonic acids and their s-carbamides synthesised by I. E.Balaban and H. King.G4 The free acids and their first s-carbamides(see formulz) are inert. Toxicity begins t o be apparent with thesecond carbamide derivatives (s-carbamide of m-aminobenzoyl-naphthylaminedisulphonic acid) and is very marked with the thirdcarbamide derivatives (s-carbamide of m‘-aminobenzoyl-m-amino-benzoylnaphthylaminedisulphonic acid). Table VIII records someof the percentage inhibitions observed.TABLE VIII.Percentage Inhibitions of Fumarase Activity by Naphthyluminedi-sulphonic Acids and their s-Carbamide Derivatives.Conc. 1 l4000.Freud’s Amino-G- C- Amino-J- H- 2R-acid. acid. acid. acid. acid. acid.Free acid ............ 1 0 0 0 3 36 1st s-carbamide ... - I2nd 9 , ... 5 32 17 19 8 953rd 9 3 ... 83 90 94 95 22 95Quastel draws attention to the parallelism which exists betweenthe inhibition of the action of fumarase and trypanocidal actionwhich, as was shown by Balaban and King, begins only at the seconds-carbamide stage of combination and is most marked at the thirdstage. The parallelism with the substantive properties of thesederivatives to cotton, which also increase from the first to the thirdcarbamide stage, is most suggestive, and Quastel argues that theremust be some structure in common between the fumarase enzyme,cotton fibre, and the trypanosome which makes for specific combin-ation or adsorption.Glyoxalase and Sodium lodoacetate.-Attention was directed in theReport of last year 65 to Lundsgaard’s investigations of the inhibi-tory action of iodoacetic acid on the formation of lactic acid bycontracting muscle.Sodium iodoacetate is not a general enzymicpoison. It does not affect glycogenolysis or the breakdown ofphosphagen. It does not interfere with the action of ptyalin orinvertase. It prevents the alcoholic fermentation by yeast without,however, affecting the oxidative metabolism. Lundsgaard formedthe opinion, which has gained general acceptance, that iodoaceticacid is a specific inhibitor of glycolysis and therefore interferes withsome stage of the degradation of glucose to lactic acid.Theseconsiderations led H. W. Dudley 66 to investigate the action of- 3 464 J., 1927, 3068; A., 1928, 164.66 Biochem. rT., 1931, 25,439; A., 766.66 Ann. Reports, 1930, 27, 269230 POLLARD AND PRYDE:sodium iodoacetate on the enzyme glyoxalase, detectable in prac-tically all mammalian tissues, where it is active in the conversion ofmethylglyoxal into lactic acid. It is found to be a powerful inhibitorof this enzymic process, and the observation has an importantbearing on the views advanced by H. D. Dakin and H. W. Dudley 67regarding the possible r6le of rnethylglyoxal as the immediateprecursor of lactic acid in the normal glycolytic chain of reactions.These views are obviously strengthened by Dudley’s new observ-ations, and it is suggested that sodium iodoacetate owes its power ofinterfering with normal glycolysis to its action as an inhibitor ofglyoxalase .Molecular Weights of Proteins.From time to time in these Reports references have been made tothe determination of the molecular weights of proteins.68 Thesereferences were mainly t o the work of T.Svedberg, whose ultra-centrifugal methodiof measuring the rates of sedimentation of largemolecules has been of the greatest service, and has in general yieldedresults in excellent agreement with those obtained by other methodswhere these have been available. In 1929 Svedberg 69 gave a shortsummary of his main results.He stated that all stable nativeproteins studied up till then might be grouped into two classes asfollows : (1) Those with a molecular weight of the order of lo6, suchas hzmocyanin, and (2) those with a molecular weight of 35-210 xlo3. The mole-cules of the first and fourth sub-group are spherical and have a radiusof 2-2 and 4.0 mp respectively, whilst those of the other sub-groupsare not spherical. The spherical nature or otherwise of the moleculeis deduced from a calculation of the molar frictional constant. Themolecules of most of the members of the fourth sub-group are easilydisaggregated by increasing the p H . At the same time it was statedthat a protein may, according to the p H of the medium in which it ispresent, appear with the molecular mass, size, and shape of anotherprotein.A further communication by Svedberg 70 conveniently summarisedhis more recent work in this field.Most of the protein molecular-weight determinations had been carried out on material purified bythe use of ammonium sulphate as a precipitating or crystallisingagent. In the attempt to isolate lactalbumin from cow’s milk it wasobserved that the molecular weight increased during purification,the figures obtained ranging from 12,000 to 25,000. It was foundthat the bulk of the native material in cow’s milk, from which theThe latter class is divisible into four sub-groups.6 7 J. Biol. Chem., 1913, 15,463.6 8 Ann.Reports, 1925, 22, 294; 1928, 25, 235, 239; 1930, 27, 34, 271.70 Ibid., 1931, 128, 999. Nature, 1929, 123, 871; A., 1929, 836BIOCHEMISTRY. 231lactalbumin was formed, had a low molecular weight, probably notexceeding 1000, and that the progressive condensation to form largermolecular complexes was due especially to the action of theammonium sulphate used in the purification. I n view of this dis-covery the molecular weights of many of the proteins previouslystudied were re-examined without any chemical treatment, or a t leastunder conditions closely resembling those of the native occurrenceof the proteins. I n the case of ovalbumin it was found that whenegg-white is diluted with 1% sodium chloride solution, the sedi-mentation consta'nt is always lower than that of purified ovalbumin,which is 3.5 x lO-I3 and corresponds to a molecular weight of34,500.71 This value represents the upper limit of the condens-ation process in the case of this protein.On the other hand, bloodserum diluted with 1% sodium chloride solution gives a sediment-ation constant which is of the same order of magnitude as that ofpurified serum albumin and purified serum globulin. I n the case ofthe vegetable seed protein amandin, a 10% sodium chloride extractof almonds showed the presence of a high-molecular protein with asedimentation constant of the same order of magnitude as that ofpurified amandin, but a substance of much lower molecular weightwas also found to be present. Hzmoglobin has in all cases givenmolecular weights of 68,000 and does not appear to be affected bythe ammonium sulphate treatment.Phycocyan and phycoerythrin( N , 208,000) from algE likewise have molecular weights which areunaffected by purification. The sedimentation constant of hzmo-cyanin is 98 x 10-13 and is constant under various conditions, as,for instance, in the undiluted blood of Helix pomatia (proteinconcentration 3%), in the blood diluted with 1% sodium chloridesolution (protein concentration 0.1 yo), and in purified hzmocyanin.This protein is therefore present in the blood of Helix with the sameenormous molecular weight, namely, 4,930,000, as in purifiedhaemoc yanin.The general conclusion made from these observations is that mostproteins do possess the same molecular weights in their native stateas in the purified laboratory products.On the other hand, thereare instances of the protein existing in the living organism as a low-molecular pro-protein which may be converted into the real proteinby the " purification " process, especially by the action of ammoniumsulphate.Attention is called by W. T. Astbury and H. J. Woods 72 to aninteresting theoretical aspect of these results on protein molecular71 See also J. T3. Nichols, J. Amer. Chem. SOC., 1030, 52, 6176; A . , 374;72 Nature, 1931, 127, 663; A., 752.13. Sjijgren and T. Svedberg, ibid., p. 5187; A., 374232 POLLARD AND PRYDE:weights. The sequence of the numbers 1, 2, 3, and 6 as multiplesof Svedberg's value of 34,500 is discussed in relation to the peptidechain and its possible crystallographic combinations. It is con-sidered that the value 34,500 is due to the vibrational instability ofpeptide chains of length greater than a certain limit.The disruptiveaction of high energy quanta on the length and cohesion of thesepeptide chains is shown in experiments on unstretched wool, which,after exposure for many hours to the full beam of a Shearer X-raytube, shows many of the properties of wool which has been exposedunder tension to the action of steam.From an examination by means of the ultra-centrifuge of theprotein fractions obtained by electrodialysis of serum, P. vonMutzenbecher '3 has obtained results which are in accord with theviews of Svedberg. Both the water-soluble and the water-insolublefraction are found to be polydisperse and the specific rate of sedi-mentation of the water-soluble fraction varies greatly, but liesbetween those found for serum globulin and albumin prepared bysalting out with ammonium sulphate.The insoluble fraction con-tains several components of high molecular weight and the resultsobtained for this fraction agree well with those found by T. Svedbergand B. Sjogren 74 for euglobulin prepared in another way. Promthe soluble fraction, after the removal of the pseudoglobulin, slightlyimpure crystalline albumin can be obtained. Both the solublefraction and the pseudoglobulin have higher rates of sedimentationin electrolyte-free solutions than in solutions containing electrolytes,and both contain appreciable amounts of components of highmolecular weight.Fractionation of the serum proteins by removalof electrolytes therefore does not lead to the production of mono-disperse systems. Only in a solution containing salts is a homo-geneous globulin molecule stable. The general conclusion is thatfor the fractionation of the proteins of serum electrodialysis is not asufficiently protective met hod.On the other hand, results which do not accord well with theforegoing have been recorded by G. S. Adair and M. E. Robinson 75in an analysis of the osmotic pressures of serum proteins. It isstated that serum albumin can be recrystallised four times withoutchange in the molecular weight. The mean value of the molecularweight of horse serum albumin is 72,000 j, 3,000.Similar valuesare found for the albumins of ox and sheep sera. The mean valueof the molecular weight of the unfractionated globulin of the horseis 175,000, and the unfractionated globulins of the ox and the sheepBiochem. Z., 1931, 235, 428; A., 1175.74 J. Amer. Chem. Soc., 1930, 52, 2855; A., 1930, 1197.76 Biochem. J., 1930, 24, 1864; A., 248BIOCHETKCSTRY. 233give similar results. Euglobulin prepared by a rapid method isfound to resemble total globulin, so that Svedberg’s value for totalglobulin, namely, 103,800, is lower than that found by Adair andRobinson, who conclude that the state of aggregation of the proteinsin the untreated serum appears to be the same as their state ofaggregation in the purified proteins prepared by the methods usedin these investigations.It must none the less be conceded thatSvedberg’s views furnish us, in certain cases, with a conception of theprotein as a labile molecule, which seems a fitting physical basis forits biological r6le.A study of horse serum globulin from a rather different standpointhas been published by J. W. McBain and E. Jameson,76 who haveanalysed their observations in a phase diagram. It is found thatthere is a great similarity to the behaviour of soap, both in respectof the forms of globulin and soap which separate and in the shapes ofthe areas representing the solutions of the two substances. Globulinsolution, euglobulin, and pseudoglobulin are regarded as being threephases of the same substance, dehydrated globulin. A solution ofglobulin is the ordinary isotropic solution, whilst euglobulin andpseudoglobulin are liquid crystalline phases, or a liquid and a glasswhich are slightly doubly refracting.The Molecular Weight of Insulin.-T. Svedberg and B.Sjogren 77have investigated by ultracentrifugal methods the molecular weightof insulin, using a crystalline preparation for the purpose. Over ap H range of 4-5 to about 7-0, insulin is stable and its sedimentationconstant has a value of 3-47 x Outside its stability rangedissociation into low molecular products takes place, but thisdissociation is reversible if the substance has not been brought toofar into the acid or alkaline region and has not been kept there toolong. At p H 6-7-6.8 a mean value for the molecular weight of35,100 is found.It is concluded thatcrystalline imulin is a homogeneous and well-defined protein of theovalbumin class, and that its synthesis is therefore a very remotepossibility. It may be remarked in passing that the experiments ofA. F. Charles and D. A. Scott 78 and of W. Corneli,79 on the action ofproteolytic enzymes on insulin, have not so far yielded any evidenceof the hydrolysis of insulin into smaller and physiologically activemolecules.The molecule is spherical.76 Trans. Faraday Soc., 1930, 26, 768; A., 376.7 7 T. Svedberg, Nature, 1931,127,438; A., 658; B. Sjogren and T. Sved-berg, J . Amer. Chem. Soc., 1931, 53, 2657; A., 1096.Trans. Roy. Soc. Canada, 1930, [iii], 24, v, 95; A., 397.2.physiol. Chem., 1931,199 217; A., 1194.H234 POLLARD AND PRYDE:A New 8ynthesis of Methionine.The amino-acid methionine, first isolated by Mueller in 1922, wassynthesised by Barger and Coyne.so A second synthesis has beendescribed by W. Windus and C. S. Marvel.81 Neither of thesemethods, however, made the substance more easily available thanthe natural product, which is very troublesome to isolate. G.Barger and T. E. Weichselbaum 82 have now described an improvedmethod of synthesis which gives a yield of 58% on the basis of thep-chloro-a-methylthiolethane employed. The latter is made toreact with ethyl sodiophthalimidomalonate and the resulting com-pound (I) is hydrolysed first with alkali t o yield the phthalamido-malonic acid (11) and then with acid to yield methionine (111) :CH3-S*CH2*CH2*C(C0,Et)2*N<co>C6H4 co (I.)1 NaoHt CH3*S*CH2*CH2*C(C0 H)2*NH*CO*C6H**C02H (11.)ECIJCH3*S*CH2*CH2*CH(NH2)*C0,H (111.)d-3 : 5-Di-iodotyrosine as a Constituent of the Thyroid Protein.The previous work of Harington has been summarised in earlierReports.83 During the past year C.R. Harington and S. S. Randall 84have recorded the isolation of d-3 : 5-di-iodotyrosine from theprotein of the thyroid gland. They were able to secure the opticallyactive acid by making use of proteolytic enzymes. Harington andRandall 85 have already described the isolation of dl-di-iodotyrosineby means of the graduated hydrolysis of the thyroid gland materialwith barium hydroxide. This work was repeated shortly afterwardsby G.L. Foster,86 who obtained 33% of the total iodine of the glandas di-iodotyrosine and 16% as thyroxine. The materials now usedby Harington and Randall for the isolation of the optically activeacid were the various mother-liquors containing acid-soluble organic-ally80818283848586combined iodine which were obtained as by-products in theAnn. Reports, 1928, 25, 233; Biochem. J . , 1928,22, 1417; A., 1929, 175.J . Amer. Chem. Soc., 1930, 52, 2575; A., 1930, 1026.Biochem. J . , 1931, 25, 997.Ann. Reports, 1926,533,234; 1928,25,261; 1930,27,274.Biochem. J., 1931, 25, 1032; A., 1178.Ibid., 1929,23,373 ; A . , 1929, 839.J . Biol. Chem., 1929, 83, 345; A., 1929, 1191BIOCHEMISTRY. 235course of the isolation by Harington and Salter 87 of 2-thyroxine bythe enzymic digestion of that thyroid gland.The filtrates from thepeptic digestion of crude iodothyreoglobulin, after fractionationwith silver nitrate, yielded a product which was subjected to trypticdigestion and finally t o the action of erepsin. After this treatmentit was possible, by a simple fractionation, to separate d-di-iodo-tyrosine in a pure condition. It showed in N-hydrochloric acid[or]5461 + 3.85". We therefore now have evidence that both Z-thyr-oxine and d-3 : 5-di-iodotyrosine are constituent amino-acids of thecharacteristic protein of the thyroid gland. These are the only twoiodine-containing compounds of the thyroid gland and the iodinewould normally appear t o be about equally distributed betweenthem, although variations in such distribution may occur and wouldaccount for discrepancies between iodine content and physiologicalactivity of thyroid preparations.A New Tribasic Acid present in Liver Extracts.Last year there was described the isolation from liver extractsby H.D. Dakin and his co-workers 88 of a dipeptide of p-hydroxy-glutamic acid and y-hydroxyproline. This substance, which wasobtained as a crystalline quinine salt, produced a strong reticulocyteresponse in cases of pernicious anzmia. In the course of the earlierwork evidence was obtained of the presence of a second quinine saltof higher quinine content,. This has now been isolated by H. D.Dakin and R. West 89 in a crystalline condition and is differentiatedfrom the first-described quinine salt by its higher melting point andoptical rotation, its lower solubility in water, and the fact that itgives no amino-nitrogen on hydrolysis.The free acid is provisionallyconsidered to have the formula (I). When the acid is administeredintravenously to cases of pernicious anzemia in the form of a singledose (0.25 to 0-75 g.), it is found that a distinct rise in reticulocytesCH3*QH-yH*CH2*CH( CO,H), CH3*$-E*CH2*CH3HO,C*H,C*CH CO --+ HO,C*H,C*C CH +\/(1.1 CH,*lj-$*CH,*CH3 (11.)NH v NHCH,*C CH\/ (111.1NHsometimes follows. But the response is neither as prompt nor asquantitatively striking as that following the administration ofAnn. Reports, 1930, 27, 274.J . Biol. Chem., 1931, 92, 117; A., 974.88 Ibid., p.273236 POLLARD AND PRYDE:structurally related substances, a description of which is promisedlater. The new acid is not regarded as being responsible for anylarge share in the reticulocyte response evoked by liver extracts.On the other hand, Dakin and West attach some importance tothe acid as a possible precursor of the porphyrin nucleus of haemo-globin. When the acid was heated in a sealed tube with excess ofbaryta at 120-130" there was obtained an ether-soluble pyrrole-carboxylic acid, CgHl3O2N, which was isolated as the picrate (pro-visional formula 11). At 155-165", hEmopyrrole was produced(provisional formula 111). Dakin and West point out that themethylmalonic acid side chain present in the new acid occurs in eachof the four pyrrole rings of uroporphyrin.From the chemicalstandpoint the acid would therefore appear to be more directly alliedto uroporphyrin than to coproporphyrin or hzmatoporphyrin, sincethe synthesis of the latter substances would require the eliminationof 4 and 6 molecules of carbon dioxide respectively from each groupof four pyrrole rings in the porphyrin nucleus.The Female Sexual (GTstrous-producing) Hormone.When the Report of last year was written the position with regardto the estrous-producing hormone was that A. Butenandt and G. F.Marrian had both satisfactorily characterised their active Erystallinepreparations as C1sH2202 and ClsH2,03 respe~tively.~O It was clearthat the two workers were handling different but very closely relatedsubstances. Marrian had identified the substance C18H2,03 as atrihydric alcohol with one phenolic hydroxyl, whilst Butenandt'ssubstance, with one molecule of water less than Marrian's, wasshown to be a hydroxy-ketone.A. Butenandt and F. Hildebrandt 91have now succeeded in isolating Marrian's substance by his methodfrom a chloroform extract. of the urine of pregnancy, and from theresidual oil obtained from the isolation of Butenandt's own substance.The latter substance (C18H2,02) has also been obtained by B.Skariy1bki,~2 whilst S. A. Thayer, L. Levin, and E. A. Doisy 93 havealso described, in a paper which makes rather inadequate referenceto the work of Marrian and of B~tenandt,~* the isolation of theClSH2,O3 substance. Butenandt and Hildebrandt have converted,by distillation with potassium hydrogen sulphate, the C18H2403Ann. Reports, 1930, 27, 271.2.physiol. Chem., 1931, 199, 243; A., 1195.g2 Ibid., 1931, 196, 19; A., 771.93 J. Biol. Chern., 1931, 91, 655; A., 879 (see nlso E. A. Doisy and S. A.Thayer, ibid., p. 641; A., 579).94 A. Butenandt and G. F. Marrian, 2. physiol. Chem., 1931, 200, 277; A.,1337; G. F. Marrian and A. Butenaadt, Nature, 1931,128,306; A., 1337BIOCHEMISTRY. 237substance into the C,8H220, substance identical with that isolateddirectly from the urine. The dehydrated substance is now charac-terised as the follicular hormone (dioxyoestrin) and the other as itshydrate (t4rihydroxycestrin). It appears that the physiologicalactivity of the hydrate is much lower than that of the hormone anddecreases with purification.Thus the hydrated product with amelting point of 276' and [a]D + 34.4" has only 2% of the activityof the hormone, but, on the other hand, the hormone prepared bydistillation of this hydrate is fully active. The two forms-thehormone and its hydrate-are not interconvertible by any of thesteps used in their isolation and both must therefore be present in theurine of pregnancy.The hormone C18H2202, like the hydrate, is acidic and G. F.Marrian and G. A. D. Haslewood 95 have shown that this acidity isdue to the phenolic hydroxyl group. Thus by subjecting trihydroxy-oestrin (1) to the dehydrating action of distillation with potassiumhydrogen sulphate, followed by met'hylation with methyl sulphate,and (2) to methylation, followed by dehydration, they have obtainedby these alternative procedures products yielding identical oximes.The dehydration product of trihydroxyoestrin monomethyl ether istherefore identical with dioxyoestrin monomethyl ether.Thisproves that in the conversion of trihydroxyoestrin into dioxyoestrinwater is eliminated from the 'two non-acidic hydroxyl groups of theformer. It also shows that the acidity of dioxyoestrin is due to thephenolic hydroxyl group and not to enolisation of the carbonylgroup.In addition to the cestrous-producing substance decribed above,both Marrian and Butenandt isolated from the urine of pregnancy asecond, but physiologically inactive, crystalline substance whichproved to be a saturated dihydric alcohol.* Butenandt called thissubstance pregnandiol and assigned to it the composition C,1H3,0,.On oxidation there was formed the saturated diketone, C21H3202,pregnandione, and by Clemmensen reduction of the latter A.Butenandt, F.Hildebrandt, and H. Briicher 96 have obtained thecorresponding hydrocarbon, C21H36, pregnane. These workers havealso prepared the same hydrocarbon by reduction, with zinc amalgamand hydrochloric acid, of aetiocholyl methyl ketone, C21H340,obtained from cholanic acid. On the basis of these results a closeaffinity of pregnandiol with the basic ring systems of the bile acids9 5 J. SOC. Chem. Id., 1931, 50, 1044.* The Reporter was in error in confusing, in the Report of last year, thisinactive substance with the active crystaIline material (see Ann.Repor&, 1930,27, 272, lines 1, 2, 22, 23).Ber., 1931, 64, [B], 2529238 POLLARD AND PRYDE:is deduced, and the formuke appended are ascribed to the alcohol,the diketone, and the hydrocarbon :CH,I CH3IPrsgnandiol Pregnandione PregnanePregnandiol is thus a neutral oxidation product of the bile acidsor sterols. It is sterically related to the coprosterol-cholanic acidseries. It is not found in male urine nor in normal female urine.On the other hand it is absent from the urine of the pregnant mare,and the indications are a t present against a specific association ofthis interesting alcohol with the condition of pregnancy.8pecif;c Carbohydrates and Immunology.(Continued from Ann.Reports, 1929,26,239-241.)W. F. Goebel and 0. T. Averyg7 have described the synthesis ofthe p-aminobenzyl ether of the specific polysaccharide of Type I11pneumococcus and the coupling of the ether, by means of the diazo-reaction, with protein. The steps in the process involved theinteraction of p-nitrobenzyl bromide and the polysaccharide, thereduction of the ether so obtained to give the p-aminobenzyl ether,the diazotisation of the latter, and finally the alkaline coupling of thediazonium chloride with the protein. The protein used was serumglobulin and the immunological specificity of the “synthetic antigen ”so obtained has been studied by 0. T. Avery and W. F. GoebeLg8The remarkably interesting result emerges that the synthetic antigenshows, in rabbits, the type-specific antipneumococcus response whichneither one of its constituents alone is capable of inciting wheninjected singly into these animals.It must be borne in mind thatthe carbohydrate alone, although specific in its reactions, has notbeen shown to be antigenic, that the antigen used in these investig-ations has in common with the Type I11 pneumococcus only thespecific capsular polysaccharide, and that the protein to which it isconjugated is of widely remote biological origin. Rabbits immunisedwith the synthetic antigen acquire an active immunity againstinfection with virulent Type I11 pneumococci, and the sera of suchimmune rabbits contain type-specific anti-substances which (a)87 J . Exp.Xed., 1931, 54,431. O6 Ibid., p. 437BIOCHEMISTRY. 239precipitate the Type I11 capsular polysaccharide, (b) agglutinateType I11 pneumococci, and (c) specifically protect mice againstType I11 infection. These results afford strong evidence in favourof the view that an effective, active immunity can be developed inwhich the only antibacterial anti-substances formed are thosedirected against the capsular polysaccharide.Avery and Goebel are careful to point out that in the present stateof our knowledge it would be hazardous to predict the precise con-ditions under which complex carbohydrates by themselves mayfunction as antigens, and that their present study simply definescertain conditions under which the Type I11 pneumococcus poly-saccharide, in chemical union with a foreign protein, is renderedspecifically antigenic in animals in which the carbohydrate alone hasnever been found to incite anti-substance formation.That suchcaution is wise is shown by a claim of J. Z o ~ a y a , ~ ~ who states thatthe anthrax specific polysaccharide adsorbed on collodion particlesis antigenic.Further advances in the chemical characterisation of the specificand non-specific polysaccharides of Type IV pneumococcus havebeen recorded by M. Heidelberger and F. E. Kendall.99aPlant B ioc h em i s t ry.Mineral Nutrients and their Eflects on Plant Growth.Mechanism of the Intake of Minerals.-Much attention continuesto be devoted to the complex problem of the manner in which theroot cell membranes of plants exert an apparent selective powerin their permeability to electrolytes and are enabled to maintainwithin the tissues a higher salt concentration than exists in thesurrounding medium.W.J. V. Osterhout maintains his view that the actual penetra-tion of electrolytes takes place in the molecular condition. Thusthe accumulation of potassium chloride in Valonia results from theentry of molecular potassium hydroxide, its combination with weakacids within the cell and subsequent conversion into potassiumchloride by hydrochloric acid molecules which have penetratedseparately. The relative permeabilities of basic molecules areassumed to depend on their respective thermodynamic potentials.The weight of general opinion, however, favours the view thatthe penetration of electrolytes is an ionic phenomenon, an interestingtheoretical discussion of which is given by G.E. Briggs.2 The9g Science, 1931, 74, 270; A., 1335.J . Exp. Med., 1931, 53, 625; A., 1335.1 J . Qen. Physiol., 1930, 14, 286, 301; A., 129.Proc. Roy. SOC., 1930, B, 107, 248; A., 129240 POLLARD AND PRYDE:suggestion is made that cell membranes exhibit alternating phasesof permeability favouring the entry of anions and kations respec-tively.The more practical aspects of this problem in its relation to thenutrient condition of soils further involve consideration of quanti-tative water movements associated with the entry of electrolytes.I n this connexion the work of J. F. Breazeale3 on the absorptionof nutrients by plants at low soil-moisture conditions is of value.A continuous film of moisture is assumed to exist between the soiland the root hairs at all moisture contents above the wilting point.The passage of ions from soil solution to plant is controlled by theirelectrical charges and does not necessarily involve the simultaneousentry of water.Provided sufficient water remains in the soil tomaintain the system, the water consumption of the plant is to alarge extent an independent process. Interesting support for thisview is given by the observation that plants may take in waterthrough portions of the root system located in moist soil andexude water from other rootlets situated in a drier soil area. Onthe other hand, there is indirect evidence of a close relationshipbetween the intake of water and of electrolytes by plants, typicalof which is the observation of B.S. Meyer4 that the addition ofsoluble salts to soil produces a marked decrease in the water require-ment of cotton plants, which is roughly proportional to the amountof salt added.It is now generally conceded that plants can absorb electrolyteswith as much or possibly even greater ease from dilute solution asfrom more concentrated ones and that with the possible exceptionof phosphates the mineral nutrients are present in natural soilsolutions in sufficient quantity for the normal growth of plants.W. U. Behrens 6 points out that the intake of nutrients from solu-tions of this order of dilution involves the expenditure of freeenergy which is presumably available from chemical reactionstaking place within the cell.A critical survey of current views on the mineral intake of plantsand of their relationship to laboratory methods for the examinationof the nutrient status of soils is given by D.R. Hoagland.'Nitrogen Assimilation.-The vexed question of the relative valuesof ammonia and of nitrates in plant nutrition has received consider-able attention recently. Although the direct intake of ammoniumArizona Agric. Exp. Sta. Tech. Bull., 1930, No. 29, 137; A., 535.4 Amer. J . Bot., 1931, 18, 79; A . , 552.F. W. Parker and W. H. Pierre, Soil Sci., 1928, 25, 337; B., 1928, 534.2. PJEanz. Diing., 1928,11, A , 93, 150; B., 1928, 683.Plant Physiol., 1931, 6, 373; A., 1202BIOUHEMISTRY.241salts is now generally recognised, as also is Prianishnikov’s con-ception that ammonia represents the first essential stage in plantmetabolism, it is doubtful whether agricultural chemists in generalare yet prepared to accept his view that the principal function ofnitrates in plant nutrition is to provide an alternative and less toxicsource of nitrogen to act as a regulator of the ammonia concentra-tion within the cells.* Among numerous investigations of the rela-tive rates of intake of ammonium and nitrate ions by plants, somedivergence of opinion is apparent. This is traceable in some casesto that ever-recurring source of confusion, vix. , the comparison ofresults of water cultures and soil cultures, and in others to the factthat assimilation rates as judged by the removal of ions from culturesolutions and as measured by the growth rates of plants are basedon two very distinct functions.Both the nitrate and the ammonium ions appear to be morereadily absorbed from dilute solutions, e.g., 0.0005N, than from moreconcentrated ones,g and under similar conditions ammonia absorp-tion predominates in the younger stages of plant growth and thatof nitrate later.lo,lls l2Nitrogen assimilation is largely dependent on the reaction of thenutrient.From neutral or slightly acid solutions, any difference inthe ease of assimilation of nitrate or ammonium ions is in favour ofthe latter. The intake of nitrates is much less affected by extremesof reaction and predominates in media of pH<5.0 and >7.0.Theoptimum reaction for the intake of both forms of nitrogen is p E 6.0appr0x.1~, 14, l5, l6 The reduced efficiency of ammonium salts invery acid media (pH <3.6) recorded by W. Mevius l7 is attributedto an unusually rapid intake of ammonia under these conditionsand to the production of a toxic alkalinity in the root sap. Asimilar explanation is offered by Willis and Davies l* for the de-pressed plant yields resulting from feeding with very concentratedsolutions of urea.In an interesting paper by M. K. Domontovitsch and A. I. Gros-chenkov,19 it is shown that nitrogen supplied as ammonium sulphateTrans. Sci. Inst. Fert. (Moscow), 1929, No. 61, 99; R., 1930, 74.K. Schmid, Diss., Hohenheim, 1930; B., 989.lo J .A. Naftel, J. Amer. SOC. Agron., 1931, 23, 142; B., 603.l1 T. L. Loo, J . Fat. Agric. Hokkaido, 1931, 30, I, 1; B., 1149.l2 L. G. Willis and E. A. Davies, N . Carolina Agric. Exp. Sta. Tech. Bull.l3 J. A. Naftel, loc. cit.l5 D. Prianishnikov, Biochem. Z., 1929, 247, 341; A., 1929, 728.l6 K. Pirschle, Ber. deut. bot. Ges., 1929, 47, 8 6 ; A., 1930, 262; Z. Pjlanz.Dung., 1931, 22, A , 51; B., 1022.l7 2. PJEanz. Diing., 1928,10, A , 208; B., 1928, 278.1928, No. 30.l4 T. L. Loo, Zoc. cit.LOG. cit. 2. P&fiz. Dung., 1929, 14, A, 194; B., 1929, 788242 POLLARD AND PRYDE:produced greater dry matter yields than as sodium nitrate but theratio of root : total plant was greater in the case of nitrate. More-over the effect of light in increasing dry matter production wasgreater when nitrogen was supplied as nitrate than as ammoniumsalts.That factors other than reaction and concentration of themedium affect the crop-producing efficiency of nitrates and ofammonia is indicated by I. G. Dikussar.20 He records that in a seriesof media containing increasing proportions of potassium, calcium,and magnesium salts the efficiency of ammonium sulphate risessteadily in media of pH 5.5 but declines in those of pH 7.0. Undersimilar conditions, increasing salt concentrations have no effect onthe efficiency of sodium nitrate at pH 5.5 but improve it at pH 7.0.It is also shown that the ash constituents of plants receiving nitrogenas ammonium sulphate are less than when sodium nitrate is supplied.The ammonium ion is said to reduce the permeability of roots tocalcium and magnesium.In a comparison of the efficiencies ofseveral forms of nitrogen the same author records that, under theconditions of his experiments, ammonium sulphate produced theheaviest yields at pH 7.0, whereas at pH 5.5 the order of efficiencywas sodium nitrate > ammonium nitrate > sodium nitrite > am-monium sulphate. In a more recent paper Prianishnikov (Udobr.Uroxhai, 1931,3, 53) records best growth of beet a t pH 7.0, using am-monium sulphate, and a t pH 5.5, using sodium nitrate. In acid mediathe use of ammonium salts reduced the intake of calcium, the effectbeing counteracted by additions of calcium sulphate. With sodiumnitrate as the source of nitrogen, increasing concentrations ofcalcium, magnesium, and potassium salts in the nutrient reducedthe yields.In a somewhat similar investigation Pirschle,21 inhis more recent paper, shows that ammonia assimilation isassociated with a relatively greater phosphate intake, and thatof sodium nitrate with a greater potash intake. It is significantthat better growth was produced by mixtures of ammonium salts,nitrate and urea than by either ammonium salts or nitrate alone.The utilisation of nitrites by plants is examined by W. Meviusand I. Dikussar,z2 who show that in neutral or alkaline solutionmaize can utilise nitrites without metabolic disturbances, since thedistribution of nitrogen in the plant tissues appears normal inrelation to the nitrogen intake. The optimum nitrite concentra-tion is approx.50 p.p.m. a t pH 7.0. With high concentrations ofnitrite protein synthesis is retarded and there follows an accumul-ation, within the tissues, of amides and ammonia but not of nitrite.20 Landw. Jahrb., 1930, 72, 79; B., 1930, 961.2 1 L O C . cit.22 Jahrb. wiss. Bot., 1930, 73, 633; B., 989BIOCHEMISTRY. 243Amino-acids may also be assimilated by plants.23 They are not,however, equally utilisable, glycine and alanine being inferior toasparagine and aspartic and glutamic acids.Intake and E#ects of Potassium.-A relatively small number ofpapers fall to be considered in this section. In connexion with thepractical use of fertilisers the question of the (‘ physiological ”reaction of potassium salts arises, and reference should be made tothe work of M.G6rski and 0. Dabr~wska.~~ The physiologicaleffect of potassium chloride is shown to be influenced by the reactionof the nutrient medium both directly and also indirectly throughits action on the anion intake of plants. In media of pH 5.7-7-1potassium chloride solutions are physiologically acid to plants andat pH <4.4 definitely alkaline.The minimum concentration of potassium in nutrients requisiteto produce optimum growth is of considerable interest in connexionwith soil solution investigations. R. P. Bartholomew and G.Janssen 25 have examined this for a number of crops and obtainedvalues varying from 0.5-3-0 p.p.m. The fact that symptoms ofpotash starvation are less frequent than might be anticipatedduring the rapid intake of potassium from such dilute solutionsis explained by the rapidity of internal transport of potash fromolder to the more rapidly growing tissues.No confirmatory evidence of the selective adsorption of theisotope K41 by plants 27 was obtained as the result of examin-ations of sugar beet by K.Heller and C. L. Wagner 28 or of cottonand wheat by H. H. L o w r ~ . ~ ~Intake of Phosphctte.-The doubt expressed by N. Comber, F.W. Parker, and others whether the phosphate concentration in thesoil solution was such as to provide for adequate plant growth hasbeen one of the principal stumbling blocks to the belief that themineral intake of plants is entirely in the dissolved condition.Further light is thrown on this problem by the work of J.W. Tid-m0re,~0 who finds that satisfactory crops of maize, tomato, andsorghum may be produced in soils having (0.05 p.p.m. of phosphatein the displaced soil solution, whereas in culture solutions a con-centration of 0.1 p.p.m. is necessary: L. J. H. Teakle31 doubtsthe possibility of a direct relation between the phosphate intake23 Ergeb. Agrik.-chem., 1930, 2, 143 ; B., 821.24 Poln. Jahrb. Land- u. Porstwirts., 1930,24,46 ; B., 456.25 Proc. Assoc. Southern Agric. Workers, 31st Conv., 1930, 242 ; B., 647.27 F. H. Loring and J. G. F. I)ruce, Chem. News, 1930,140, 34.28 2. anorg. Chern., 1931,200,105; A., 1342.29 J . Amer. Chem. SOC., 1930,52,4332; A., 141.30 J . Amer. SOC. Agron., 1930, 22, 481; A , , 83.s1 Plant Physioi., 1929, 4, 213244 POLLARD AND PRYDE:of plants and the concentration of phosphate in the nutrient medium.If such a relationship exists, it seems likely to lie within the range0.1 to 1.0 p.p.m.of phosphate in the medium. A similar figure isarrived at by F. W. Parker and W. H. Pierre.32Relationships between the intake of phosphates and of othermineral nutrients were examined by 0. Owen 33 during investigationsof the possible use of the tomato as an indicator of the nutrientrequirement of soils. A relationship exists between the supplyof potash in soils and the intake of phosphate and vice versa. Thephosphate and potassium contents of the leaves of the tomato areinversely related, whereas in the fruit the relationship is probablydirect.S. H. EckersonJx also working with tomatoes, gives afurther instance of the inter-related effects of nutrients and of thedifficulty attending the interpretation of results of direct observ-ations of plant growth. Plants supplied with adequate nitratebut deficient phosphate show symptoms of nitrogen starvation.In this case phosphate exhaustion is followed by a cessation ofcatalase activity and the breakdown of normal metabolism is shownby the accumuIation of nitrates, sugars, and starches and an in-creasing acidity.The essential character ofboron in the mineral nutrition of plants has been emphasised inrecent years by Haas and his colleagues with citrus, by E. S. John-son 35 with potatoes and tomatoes, and by T.R. Swanbach 36 withtobacco.The minimum requirement of boron in nutrient solutions set byA. L. Sommer and C. B. Lipman3' at 0.5 p.p.m. has since been con-firmed by several workers. The effects of boron deficiency seemvaried. A. L. Sommer and H. Sorokinzs record abnormal rootdevelopment and extensive changes in the structural tissues. A. R.C. Haas and L. J. Klotz 39 show that boron is essential to cell divisionin the meristematic tissue of growing points, and in an interestingpaper from A. I. Smirnow,40 boron is shown to regulate the growthof stems with respect to root and leaves in tobacco. No effect onnitrogen storage or metabolism in tobacco could be ascribed toSecondary Plant Nzl.trients.-Boron.3 2 LOC. cit.33 J . Agric. Sci., 1931, 21, 442; A., 1200; ibid., 1919, 19, 413; B., 1929.34 Contr.Boyce Thompson Inst., 1931, 3, 197; A . , 1200.35 Soil Sci., 1928, 26, 173; B., 1929, 222; also (with DorB), Science, 19.28,36 Plant Physiol., 1927, 2, 475.3 7 lbid., 1926,1, 231.39 Hilgardia, 1931, 5, No. 8, 175; A., 1340.40 U.S.S.R. StcGts Inat. Tobacco Invest. Bull., 1930, No. 30; B., 457.732.67, 324.38 Ibid., 1928, 3, 237; A . , 1929, 855BIOCHEMISTRY. 246boron. Relationships between boron deficiency and susceptibilityto disease in plants are indicated by F. M. Eat0n.~1 Spot blotchin cereals did not appear in cultures free from boron, but increasedin intensity with the amount of that element applied. On theother hand, powdery mildew appeared only in the absence of boron.Chemical features of boron deficiency include increasing gumformation and high carbohydrate accumulation in leaves.In anygeneral consideration of experimental results of this nature dueregard must be paid to the significant observation of A. R .C. Haas 42that plants can usually obtain sufficient boron for normal growthfrom the glaze of the earthenware jars frequently used in plantculture investigations.Beneficial effects on plant growth resulting from appfic-ations of copper in fungicidal preparations, together with the generaldistribution of copper both in soils and in plants, have contributedto the belief that this element may be essential to plant nutrition.Definite proof of this is difficult to establish, since the minimumamount of copper required by plants now appears to be verysmall and, further, the accumulation of copper in seeds is shownto be very general.Earlier observations of C. B. Lipman andA. L. Sommer 43 indicated that in the absence of copper the pro-duction of flowers appeared restricted even in plants otherwiseappearing normal. Further work by C. B. LipmanandG. Mackinney44not only conhms the failure of barley to produce seed in copper-free nutrients but suggests that copper is necessary for phases ofplant growth other than flower and seed formation. In experimentswith flax, tomatoes, and sunflowers by A. L. Sommer 45 extremelypoor growth is recorded in the absence of copper, whereas theaddition of as little as 0.06 p.p.m. produces 12-40 times as muchgreen matter.The effect of copper deficiency does not appear inthe plants until 5-7 days after the transference of seedlings tocopper-free media. The suggestion is made that copper acts asan auto-oxidant in plant metabolism.The effects of copper and other heavy metals on the growth offungi are considered below.Iodine. Little of importance has been added to our knowledgeof relationships between iodine and plant growth. The stimulativeeffects recorded some years ago by 0. Loew and Stoklasa have byno means received general confirmation 46,47 ; and the few papersCopper.41 Phytapath., 1930, 20, 967; B., 269,42 Bot. Gaz., 1930, 84, 410; B., 1930, 834.44 Ibid., 1931,6,693; A., 1201.4 6 T. von Fellenberg, Mitt. Lebensm. Byg., 1927, 18, 263.4 7 H. Elleder, Z.€@wz+z Diirag., 1928,12, A , 87 : B., 1928, 796.43 Plant Physiol., 1926, 1,231.4s Ibid., p. 339 ; B., 733246 POLLBRD AND PRYDE:appearing in the current year’s literature report effects of an oppositecharacter. I n culture solutions as little as 1.27 p.p.m. of iodinedepressed growth.4s The more cxtensive researches of K. Scharrerand his co-workers 49 show that in soil cultures, iodide, iodate, andperiodate of potassium injure the germination and developmentof cereals to extents which decrease in the order named. I n watercultures similar results were obtained, the degree of injury of varioussalts being in the order potassium iodide >sodium iodide> aqueousiodine> potassium iodate> sodium iodate> potassium periodate>sodium periodate.Although the crop-increasing effects of iodinecompounds lack adequate confirmation, the increased iodine contentof crops grown with “ iodised ” rxanures 5O appears to be definitelye~tablished.~~ The significance of this point in relation to humanpathology, together with a comprehensive survey of the generalposition of iodine in agriculture, is given by W. Gaus and R.Griessbach. 52Sodium. The long-standing problem of the r6le of sodium inplant nutrition is revived but not greatly clarified by the observ-ations of P. de S ~ r n a y , ~ ~ which indicate considerable selectivity inthe assimilation of potassium and sodium among different speciesof plants. The sodium content of sugar-cane leaves, normallysmall in comparison with that of potassium, increases considerablyduring the ‘early stages of ripening.With restricted phosphatesupplies, the intake of sodium declines and relatively large amountsof potassium, together with iron and chlorides, accumulate in theleaves. Coconut palms even when grown a t great distances fromthe sea accumulate large proportions of sodium chloride. 0.Eckstein54 reports beneficial effects on the growth of oats fromadditions of sodium salts to soils of low sodium content but highadsorptive power. In soils of low adsorptive capacity sodiumsalts depressed growth, presumably as a result of relatively highconcentrations in the soil solution. V. Vincent and 5. Herviaux 55attach importance to the accumulation of sodium in parts of plantsin which physiological activity is greatest.This accumulation ismore marked in plants grown on acid soils.Manganese. Although considerable attention has been given4 s M. Cotton, Bull. Torrey Bot. Club, 1930,57, 127; A , , 537.4s K. Scharrer and W. Schropp, Biochem. Z., 1931,236, 187; 239, 74; A.,50 K. Scharrer et al., Angew. Bot., 1927, 9, 187 ; Naturwiss., 1927,15, 539.5 1 Von Fellenberg, Zoc. cit.52 2. PJlanz. Diing., 1929,13, A , 321 ; B., 1929,570.53 Bull. Assoc. Chim. SUCT., 1930, 47, 370; B., 409.54 Ergeb. Agrik.-chem., 1930, 2, 125; B., 606.5 6 Ann. Sci. agron. franp., 1929,46, 444; B., 1930, 962.1099,1200BIOCHEMISTRY. 247to the importance of this element in the chemistry of soils, itsbearing on plant nutrition has received little examination recently.In experiments with ChEoreEEa, E.F. Hopkins 56 observes thatincreased growth due to the presence of manganese increases withthe alkalinity of the medium. The optimum concentration of theelement is 1 in 5,000,000, whereas the lower toxic limit is 1 in 50,000.The function of manganese is assumed to be that of regulating theratio of ferrous to ferric iron within the tissue. W. B. S. Bishop 57has examined the effects of manganese a t various concentrationson plant growth. Manganese is normally concerned with chloro-phyll activity and carbon aasimilation. Higher concentrations donot become toxic as a result of reduced iron intake. Additionsof calcium counteract manganese toxicity. Further examplesof the apparent association of pathological conditions with man-ganese deficiency aregiven by G.Samueland C. s. Piper 58 in thecase of speck disease in oats, by H. A. Lee and J. S. McHargue 59with the Pahala blight of sugar cane, and by L. G. Willis in thedebatable question of chlorosis.The Chemistry of Plant Juices.There has been a considerable revival of interest in this subjectconsequent upon many attempts to correlate the composition ofplant fluids either with the metabolic changes and distribution ofvarious plant constituents or with external nutritional conditions.For the latter purpose, difficulties in the interpretation of resultsare often associated with the obvious practical difficulty of assessingdifferences between the contents of the rising stream of nutrientand of cell fluids containing partly or wholly metabolised materials.Meyer 61 has emphasised the fact that the nature of the solublematter expressed from green plant tissues depends considerablyon the technique employed in obtaining it, and more particularlyon any form of preliminary treatment of the material which mayaffect its moisture content.This is further confirmed by J. D.Sayre and V. H. Morris.62 The expressed juice from materialsubjected to a preliminary grinding process contained practicallythe same amount of sugar in the successive portions extracted.Preliminary mincing, however, resulted in a steady decline insugar content as successive fractions were removed. The use ofhigh pressure (5000 lb. per sq. in.), followed by pressure filtration5 6 Science, 1930, 72, 609; A., 400.5 7 Australian J .Exp. Biol. &led. Sci., 1928, 5, 125; A., 1928, 1060.6 8 J . Dept. Agric. S . Australia, 1928,31, 696; A., 1928, 1064.59 Phytopath., 1928, 18, 775.6O N . Carolina Agric. Exp. Sta. BuU., 1928, No. 267; B., 1929, 408.61 Plant Physiol., 1929,4, 103. Ibid., 1931,6, 139; A., 775248 POLLARD AND PRYDE:of the expressed juice, is advocated. A serviceable press for smallamounts of material is described by W. Leach.63 Examinationof the pH and phosphate contents of expressed juices obtained atvarious pressures by M. M. McCool and W. J. Youden indicatesa steady decrease in these values with rising pressure. A furthervariation in technique involves the killing of the tissue by immersionin hot water prior to expression of the sap.65 Juices so obtainedhave a much higher osmotic pressure than those from similar butliving tissue.It is stated that this difference is not the outcomeof decomposition of plant constituents resulting from the preliminarytreatment.Physical Properties.-In many respects, investigations of plantjuices are still in a very undeveloped stage, and such physicalcharacteristics as are easy of determination have, very naturally,formed the basis of much research of a pioneering character. Thusthe freezing points and specific conductivities of juices from variousorgans of sorghum plants are measured by J. H. Martin, J. A.Harris, and I. D. Jones,G6 and the values compared at different stagesof growth.It is of interest to note that under low soil moistureconditions these physical characteristics were not appreciablyaltered, nor was any evidence obtained of the presence of colloidally" bound " water in the juices. Among different varieties of sorghumthe specific conductivity of the juices showed considerable variation,but the freezing points were not very different. Use has also beenmade of these physical properties in attempts to elucidate relation-ships between the concentration of nutrients in the soil solutionand that of the plant juices. J. A. Harris and T. A. Pascoe 67indicate a positive correlation between the freezing-point depression,specific conductivity, and sulphate content of cotton-leaf juices andthe specific conductivity and soluble sulphate content of the soil.Reaction.-Other investigators have utilised the reaction of plantsaps as a basis of comparison. Changes in the pH of nutrient mediaproduce changes in internal sap reaction which are greater in rootsaps than in those of leaves.6s In an interesting investigationR.A. Ingalls and J. W. Shive 69 find the hydrogen-ion concentrationof plant juices t o vary inversely with the light intensity to whichthe plants are exposed, differences being greater in fleshy- than inthin-leaved plants. The soluble iron content of the juices varies63 Ann. Bot., 1931, 45, 537; A., 1201.64 Contr. Boyce Thompson Inst., 1931, 3, 267; A , , 1201.6 5 H. Walter, Ber. deut. bot. Bes., 1928,46, 639; A., 1929, 360.66 J.Agric. Res., 1931, 42, 67; A., 775.O 7 Ibid., 1930, 41, 767; A,, 399.89 Pkmt Physiol., 1931,6, 103; A., 776.. 6 8 Pknh [Z. wiss. BioZ.], 1931,12, 676; A., 775BIOCHEMISTRY. 249with the hydrogen-ion concentration. Plants whose juices arecharacterised by low hydrogen-ion concentrations have high total-and low soluble-iron contents, the order being reversed in juicesof high hydrogen-ion concentrations. An examination of the differ-ences in pH of the fluids dram from various organs of the sameplant is described by J. D. Sayre 7O in the case of maize. Greatestacidity exists in the sap of sheath tissues. The buffer capacityand also the phosphate, nitrate, total nitrogen, amino-acid, andcolloid contents are much greater in juices from sheath and leaftissues than in those from the stems.From time to time it hasbeen suggested that the reaction of plant juices is related to theextent of injury by boring and sucking insects. In the case ofmaize, neither pH nor the total acidity could be correlated withinfestation by the European maize borer. J. M. Robertson andA. M. Smith'l have recorded changes in the reaction of potatotuber sap. In the dormant stage little difference exists in thedistribution of aoidity in various parts of the tuber. The beginningof sprouting is associated with rising acidity in areas adjacent toactive eyes, this being a result of internal changes and independentof the pE of soil. During growth the acidity of the sap increasesas maturity is approached. Sigdcant changes in pH are associatedwith the incidence of disease.A similar investigation of changesin the reaction and other characteristics of the juices of Frenchbeans during various stages of growth is recorded by C . N. Acharyaand B. N. Sa~tri.'~ The reaction and buffer system of plant juicesare examined by C. T. I n g ~ l d , ~ ~ who stresses the importance of thecarbon dioxide present, not only in actual determinations of pHvalues but in the more general consideration of composition andphysiological activities. In the sap of potato tubers the principalbuffer agents are the citrates, malates, and phosphates present, theeffects of proteins, asparagine, and oxalates being of surprisinglylittle significance in this respect. The buffer index (p) of saps maybe represented as the summation of the indices of all the singlebuffer systems present over any given range.The @-curves areU-shaped, and to their form, proteins and amino-acids contributevery little. S. H. Martin and c o - ~ o r k e r s , ~ ~ in a series of papersdealing with sunflower and other plants, arrive at similar conclusions.Inorganic Constituents.-Changes in the base contents of sapswith growth have been examined, in most cases with a view to70 Ohio Agric. Exp. Sta. Bull., 1930, No. 446, 38; A., 399.7 1 Biochem. J . , 1931,25,763; A., 1102.72 J . Indian Inst. Sci., 1931, 14, A , 1; A., 1102.78 Protoplasma, 1930, 9, 441, 447, 456 ; A., 272.74 Ibid., 1927,1, 497, 522; 2, 45; 1928,3, 273, 282; A., 1928, 92, 1406250 POLLARD AND PRYDE:correlation with corresponding concentrations in nutrient media.Thus the nitrate content of the sap of maize is observed by N.A.Pettinger 75 to be closely correlated with that of the soil bearingthe plant, and the phosphate content of the sap with the amountof fertiliser applied. There is also a somewhat obscure but never-theless definite proportionality between the brown coloration ofthe clarified press juice and the available potash content of thesoil. These relationships are considered sufficiently rigid to permitthe utilisation of sap analyses as indications of the nutrient statusof soils. The p H of the saps examined is closely correlated withamounts of potash fertiliser applied to the soil but not with theinitial potassium content of the soil.M. M. McCool and M. D.Weldon 76 examined the saps of a number of agricultural cropsand observed a general relationship between the concentration ofindividual ions in the saps and the proportions of these added tosoil in the form of fertilisers. A deficiency of any one essentialnutrient such as would reduce the growth rate of the plant is fol-lowed by an abnormally high accumulation of other nutrients in thesap. The subsequent addition to the soil of the deficient elementtends to bring the concentration of all nutrients in the sap to anormal proportion. An interesting observation is reported by E.Canals, J. Canay6, and E. Cabanes,77 who show that sodium,potassium, magnesium, and phosphates present in plant juices arealmost entirely dialysable, whereas calcium in nearly all cases isin a non-dialysable form.Indications of a process akin to baseexchange between kations in nutrient solutions and those in plantsaps are given by P. G e n a ~ d , ~ ~ who examined the press juices ofcells after exposure to solutions of electrolytes. Equilibrium be-tween kations within and without the cells is reached in accordancewith the law of mass action. Results of a similar character areobtained by W. C. Cooper and W. J. V. O s t e r h ~ u t . ~ ~ The intake ofammonia by Valonia is followed by pH changes in the sap and adepletion of potassium.Formation and Distribution of Certain Plant Constituents.Nitrogen Compounds.-Growing interest in the nitrate-reducingpowers of the roots of various species of plants is exemplified bythe work of W.Dittrich,so who suggests a system of plant classific-ation based on the capacity for nitrate accumulation. The reduc-7 5 J . Agric. Res., 1931, 43, 95; B., 1111.76 J . AmeT. SOC. Agron., 1928, 20, 778; B., 1929, 106.7 7 Bull. SOC. Chim. biol., 1930, 12, 1022; A., 1930, 1482.78 Rev. gCn. Colloid., 1930, 8,241; A., 1930, 1482.79 J . Bm. Physiol., 1930,14, 117; A., 1930, 1483.80 Planta [Z. wiss. Biol.], 1930,12, 69; A., 130BIOCHEMISTRY. 25 1tion of nitrates is ascribed to enzymic action and as such is largelycontrolled by the pH of the plant sap. Optimum reducing poweris associated with pH 7.6 in the sap. Marked differences existbetween the reducing power of stem saps and those of roots andleaves.Nitrate-accumulating plants utilise this form of storednitrogen when external supplies are exhausted, e.g., when grown inmedia containing carbohydrates only.Numerous investigations of the distribution of the nitrogen ofplants under various conditions of growth have appeared. Thetranslocation of nitrogen and the rates of synthesis or decompositionof protein within the plant are largely controlled by the water presentin the tissues. According to K. Mothes81 a deficiency of waterinduces protein decomposition and reduced carbon dioxide pro-duction in older leaves and simultaneously a synthesis of proteinand increased respiration in younger leaves. Under these condi-$ions the younger portions of the plant would appear to continuetheir growth a t the expense of the older portions.Much interest centres round nitrogenous changes in fruit trees.A.S. Mulay 82 records a winter accumulation of nitrogen in the barkof Bartlett pear shoots, falling steadily during the growth periodand recurring as the dormant season approaches. These changesfall mainly on the insoluble nitrogen fraction. Correspondingchanges occur in the total nitrogen of the woody tissues, but herethe soluble nitrogen is mainly concerned in the fluctuations. Thesoluble protein, which forms 6-12% of the total nitrogen of thebark, accumulates towards autumn and decreases again as springapproaches. In the wood, similar variations occur, although thesoluble proteins are present in smaller proportions than in thebark.Potter 83 and his colleagues in New Hampshire have madesomewhat similar investigations with apple spurs, with specialreference to conditions coincident with fruit bud formation. Infruiting spurs the total nitrogen is higher and starch content lowerthan in non-fruiting spurs. Fruit bud formation is associated withan accumulation of insoluble nitrogen and a lowered proportion ofsoluble carbohydrate. The association of shoot production withstem areas containing accumulations of nitrogen is shown also byP. A. D a v i e ~ , ~ ~ who finds that cuttings of XaZix nigra develop rootsfrom stem areas of low nitrogen content and shoots from those ofhigh nitrogen content.81 Planta [Z. wiss. Biol.], 1931,12, 686; A., 660.*2 Plant Physiol., 1931, 6, 333, 519; A., 990, 1197.8s G.F. Potter, H. R. Kraybill, S. W. Wentworth, J. T. Sullivan, and P. T.Blood, New Humps. Agric. Exp. Sta. Tech. Bull., 1930, No. 41; A., 400; G .F. Potter and T. G. Phillips, ibid., No. 42; A., 400.*4 Bot. Gaz., 1931, 91, 320; A,, 883252 POLLARD AND PRYDE:Reference should be made to a very thorough examination ofboth nitrogenous and mineral constituents of the oat plant fromthe seedling stage to maturity by T. W. Fagan and J. E. Watkin 85;and also to papers by M. Steiner and H. Loffler 86 on the distributionof ammonia and volatile amines in various plants, and by G. M.Armstrong and W. R. Albert,87 on the effect of fertilisers on thenitrogen distribution in cotton.Carbohydrates .-Seasonal variations of the carbohydrate dis t ri -bution in plants have again formed the subject of a number ofinvestigations.In the roots of Geum urbanum, J. Cheymol 88records accumulations of mono- and di-saccharides, hydrolysableby emulsin, during periods of reduced chlorophyll activity, ofpolysaccharides in proportion to the vegetative activity of the plant:and of geoside, which occur mainly in the spring. Storage of carbo-hydrates in stem bases in dormant periods is also recorded in thecase of Xtipa pulchra by A. W. Sampson and E. C. McCarty,s;together with significant data of carbohydrate metabolism bearingon the system of intensive grazing. Thus, regenerative growthfollowing cutting or grazing leads to utilisation of the carbohydratereserves. In the younger stages of growth, cutting does notseriously reduce the final accumulation of carbohydrate whenvegetative growth ceases; but if cutting is delayed until after theflowering stage, the maximum carbohydrate storage for the dormantseason is not developed and reduced growth in the ensuing seasonmay result. The association of rapid growth in trees with the appear-ance of relatively high proportions of reducing substances is referredto in an examination of sugar prunes by L.D. Davis.go In a com-parison of bearing and disbudded trees during periods of activegrowth, the former were characterised by high proportions ofreducing substances and low starch contents in the aerial partsand low starch contents 'in the roots.A series of papers by M.Samec and colleagues 91 makes a notableaddition to the chemistry of starches. Characteristic differencesbetween amylo- and erythro-substances are examined. In solsobtained by boiling potato starch with water under pressure,amylo-substances are the more strongly absorbed by cotton. Theviscosity of amylo-sols increases fairly rapidly with rise of temper-8 5 Welsh J. Agric., 1931, 7, 229; A., 1339.8 6 Jahrb. wiss. Bot., 1929, 21, 463; A., 1931, 990.8 7 J. Agric. Res., 1931, 42, 689; B., 775.8 8 Bull. SOC. Chim. biol., 1931, 13, 470; A., 883.89 Hilgardia, 1930, 5, 61 ; A., 660.80 Ibid., 1931, 5, 119; A., 1339.9 1 [With E. Pehani], Kolloidchem. Beih., 1931, 33, 103; A., 941; [withR. Klemen], ibid., p. 254; A., 1198; [with D. Andrib], ibid., p.269; A., 1124BIOCHEMISTRY. 253ature, and is considerably altered by the presence of neutral salts.Erythro-sols, under these conditions, are but little affected ; butare the more readily hydrolysed by acids and by hydrogenperoxide. Amylo-substances are concluded to be more highlyassociated and hydrated and to carry greater electric charges thanerythro-substances. Amylo-pectins obtained by the fractionaldissolution of starches are shown to contain fatty acids, and maybe used in conjunction with data of X-ray.spectra as a basis for ageneral classification of starches into two groups typified by potatoand wheat starches. The migration velocities of the constituentsof potato starch are in the order amylo-pectin>amylose>erythro-amylose.In a later paper92 the isolation of starch derivatives of highphosphate content is described.One of these appeared, from itsmolecular weight and phosphorus content, to be of intermediatecomposition between a compound of 1 molecule of phosphoric acidwith a di- and a tri-saccharide. The neutralisation curve of thissubstance exhibits two discontinuities resembling those of phos-phoric acid itself. The isolation of this compound( 2) has a signi-ficant bearing on the nature of “ phytovitellin” previously rec~rded.~sPhytovitellin contains both nitrogen and phosphorus associatedwith the polysaccharide and linked w5th it through the phosphorusradical. This combination appears weaker in wheat than in potatostarch. Preferential removal from wheat starch of nitrogen withrespect to phosphorus by alkali leaves a residue exhibiting proper-ties similar to those of potato starch and containing electrochemic-ally active phosphorus.Further treatment with hot water removesa substance containing phosphorus, and the starch reverts to thewheat type.The nature of hemicelluloses has been examined by I. A. Preece 94and by E. Anderson.95 The former author concludes that freehemicellulose is a simple urono-xylan, while the latter assumesthe existence of a second type of hemicellulose yielding aldobionicacid on hydrolysis, thus resembling the plant gums. A generalsurvey of the chemistry of hemicelluloses is given by S. A. Waksmanand R. A. Diehm 96 in an introduction to an extensive investigationof the decomposition of these substances by micro-organisms.The distribution of lignin in woody tissues, examined after92 M.Samec [with S . Selisker and V. Zitko], Kolloidchem. Beih., 1931, 33,g3 M. Samec [with W. Bendger], {bid., p. 95; A., 941.94 Biochem. J., 1931, 25, 1304; A., 1198.9 5 J . Biol. Chem., 1931,91,659; A., 884.96 Soil Sci., 1931, 32, 73, 97, 119; A , , 1192.449 ; A., 1277254 POLLARD AND PRYDE:removal of cellulosic material, appears to vary in woods of differenttypes. From hardwoods the lignin residue consists only of themiddle lamella, whereas that from soft woods contains secondarylayers in additi~n.~' In jarrah wood, H. E. Dadswell98 describesthe lignin as occurring in fine radial lines in the cell walls. Hiswork further suggests that chemical combination of cellulose andlignin in wood cells is unlikely.The possibility that a high lignincontent in wheat straw is conducive to lodging by causing extremebrittleness is suggested by J. Davidson and M. Phillips.99In a suggestive investigation of lignins from a variety of plants,relationships are suggested between the botanical origin of ligninsand the position of the principal maximum in their ultra-violetabsorption spectra. Such spectroscopic evidence confirms thepresence in lignin of partially methylated di- and tri-hydric phenolgroups.Further optical investigations of wood fibres by K. Preudenberg,F. Sohns, W. Diirr, and C. Niemann2 lead to the assumption thattwo stages occur in the formation of lignin, vix., (1) the condensationof many (probably 12) molecules of hydrated 7-3 : 4-dihydroxy-phenyl-ap-propylene glycol to form a chain in which the freephenolic groups may be methylated, and (2) condensation orpolymerisation of these chains into larger aggregates by chemicalaction or possibly as a post-mortem process.GZucosides.-Several new glucosides have been isolated anddescribed, and further investigations are recorded of the structureof others already known.From Salix purpurea, C. Charaux and J.Rabat6 3 have obtained the p-glucoside, salipurposide, m. p. 227",a monoglucoside, C,,H2,0,,, yielding on hydrolysis dextrose andthe phenol, salipurpol, C,,H,,O,.Salireposide,4 m. p. 206", has been obtained from the bark ofSaZix repens. Hydrolysis with dilute acid yields dextrose, benzylalcohol, and an unknown phenol.Gaultherioside, isolated from Caultheria procumbens,5 is hydrolysedto dextrose, xylose, and ethyl alcohol.It is not hydrolysed byrhamnodiastase. From black alder bark, M. Bride1 and C. Charaux 69 7 W. M. Harlow, Ind. Eng. Chem., 1931, 23, 419; A., 883.98 J . Counc. 2%. Ind. Res. Australia, 1931, 4, 185; A., 1339.99 Science, 1930, '42, 401 ; A., 537.1 R. 0. Hertzog and A. Hillmar, Ber., 1931, 64, [B], 1288; A., 942.2 Cellulosechem., 1931,12, 263 ; A., 1278.3 Compt. rend., 1931, 192, 1478; A., 1199; Bull. SOC. Chim. biol., 1931, 13,4 N. Wattiez, Bull. SOC. Chim. biol., 1931, 13, 658; A., 1100.6 Compt. rend., 1930,191,1161,1374; 1931,1W&1269; A,, 131,274,886.590, 814; A., 1100, 1341.J.Rabat6 and S . Rabat6, ibid., p. 604; A., 1100BIOCHEMISTRY. 255prepared frangularoside, C21H200,, a rhamnoside yielding an un-known product , frangularol, on hydrolysis. Frangularoside in thebark exists in a form of combination from which it is liberated byan enzyme present in the bark. The parent substance, on hydrolysiswith acid, yields a considerable proportion of emodol, and withyeast, 1 molecule of frangularoside to 2 molecules of dextrose.E. Walz 7 publishes an extensive examination of some glucosidesof the soya bean, from which genistin, daidzin, and three saponin-glucosides were obtained. To genistin, from which dextrose andgenistein are produced on hydrolysis, is ascribed the formula (I),R COdaidzin having a similar formula with R = H.The three saponin-glucosides (aglucones) are characterised bythe presence of both pentose and dextrose residues, accompaniedby flavone derivatives.It is probable that one of these is a hydroxy-methyl derivative of 8-hydroxyisoflavone.Further investigations of natural glucosides by A. Robertsonand colleagues have elucidated the structure of hesperidin, to whichis assigned the formula (11).In an interesting paper A. Cugnac 9 shows that the glucosides ofEuropean Graminem are principally of the lsvulosan type whereasthose of warmer climates contain sucrosans. The lzevulosans occurin the stems and tend to accumulate in the roots, particularly inlater season of growth.Organic Acids.-Among investigations of the distribution of thesimpler organic acids of plant materials, should be mentioned thoseof Nelson and his colleagues, who have examined the commoncereals and a number of vegetables.10 Oxalic, citric, and malicacids are common to the vegetable plants.Wheat, barley, maize,oats, and rye all contain aconitic, malic, citric, and small amountsof oxalic acid and in addition malonic acid is found in wheat, barley,and oats, and tricarballylic a,cid in barley and maize. The presenceand function of oxalates in seeds and fruits is the subject of a seriesof papers by A. Niethammer, in whose view the separation ofAnnalen, 1931, 489, 118; A., 1304.* F. E. King and A. Robertson, J., 1931, 1704; A , , 1040.9 Bull. SOC. Chirn. biol., 1931, 13, 126 ; A., 661.10 E.K. Nelson and H. Hasselbring, J . Amer. Chem. SOC., 1931, 63, 1040 ;A., 601 ; E. K. Nelson and H. H. Mottern, ibid., pp. 1909,3046 ; A., 884, 11 99266 POLLARD AND PRYDE:calcium oxalate crystals in fruit cells results from the presenceof carbonaceous material in excess of immediate requirements andis a temporary storage phenomenon rather than the deposition ofunutilisable material. The crystals gradually disappear as thefruit ripens and with this disappearance there is associated theformation of acetaldehyde.11 This temporary formation of calciumoxalate is observed in a wide range of fruits and seeds.us 13Aluminium.-It is convenient here to consider the question ofthe presence of aluminium in plants. Much has been written ofthe relationship between soil acidity and the injurious effects ofaluminium on plant growth, but considerable difference of opinionexists as to whether acid soil injury is entirely attributable to thepresence of soluble aluminium.It is now shown14 that in watercultures lettuce can withstand considerable changes in acidity(pE 7.5-3.2) without appreciable injury, whereas the presence ofextremely small amounts of aluminium has a marked inhibitoryeffect. Barley yields in soils, however, are closely correlated withthe amount of " active " aluminium present.l5 The susceptibilityof different species of plants to aluminium poisoning varies con-siderably and in many cases a highly acid medium is not a necessarycondition for aluminium injury.16More recently the position of aluminium as a normal constituentof plants has received attention.In the early work of Burgess andPember17 an accumulation of aluminium in roots and leaves ofacid-soil plants was observed and little appeared in the stems.Other investigators record similar observations.l*, l9 G. Bertrandand G. Levy20 have traced variations in the aluminium contentsof a number of edible roots with age. Greatest accumulations ofaluminium occur in leaves, those of spinach, rhubarb, and radishbeing particularly rich in this element (100-280 mg. per. kilog.dry weight). A detailed examination of the leaves of mulberry grownon various types of soil indicates considerable quantities of alu-l1 Planta [ Z . wiss. Biol.], 1930, 12, 63, 399; A., 133, 537; Biochern.Z . ,1930, 227, 462; A., 133.l2 Z . Unters. Lebensm., 1931, 61, 103, 217; A., 885.l3 J. Greger, Planta [Z. wiss. Biol.], 1930, 12,49; A., 133.l4 B. E. Gilbert and F. R. Pember, Soil Xci., 1931, 31,267; B., 604.l5 Burgess and Pember, Rhode I. Agric. Exp. Sta. Bull., 1923, No. 194.l6 F. T. McClean and B. E. Gilbert, Soil Sci., 1927, 24, 163; B., 1937, 855 ;l' L O C . cit.la E. V. McCollum, 0. R. Rask, and J. E. Becker, J. Biol. Chem., 1928,77,19 L. Kahlenberg and J. 0. Cloes, ibid., 1929, 83, 261; 1930, 85, 783; A . ,2o Compt. rend., 1931,102, 626; A., 662.Plant Physiol., 1928, 3, 293.753; 1930,85, 779; A., 1928, 793; 1930, 492.1929,1098; 1930,492BIOCHEMISTRY. 257minium in the intracellular juices in all cases, stems, bark, and leafveins having higher proportions than the soft leaf tissues.It isconsidered unlikely that aluminium can enter the plant in suchquantities as were observed and be deposited in the tissues withoutbeing concerned in some a t least of the metabolic processes of theplant 5.21Nutrition and Composition of Plants as related to the Incidence andControl of Diseases.The steadily increasing interest in the control of plant diseases,both by direct application of chemical poisons and indirectly bythe elimination of predisposing causes due to faulty nutrition, hasresulted in the publication of numerous investigations on thissubject. The majority of these are more properly considered fromthe agricultural point of view. However, since the more purelybiochemical aspects of these problems are becoming increasinglyapparent, certain typical investigations seem suited for inclusionhere.Nutritional factors have been shown to play an importantpart in the spread of “ wildfire ” in tobacco.22 As has been notedin a number of instances, the greatest predisposing causes are adeficiency of potash and a relative excess of nitrogen. The effectof phosphates seems much less definite. A deficiency appears toincrease the plant’s susceptibility but, on the other hand, generousapplications of phosphatic manures do not produce a correspondinglyincreased resistance. I n this case soil reaction was a relativelyunimportant factor. The existence of such relationships is alsoindicated by investigations from a rather different point of view.I n many cases diseased plants contain significantly different pro-portions of mineral and other constituents from normal plants.Thus palms, infected with “ decline ” disease, have lowered contentsof nitrogen, phosphorus, and potassium, higher calcium, and lesscarbohydrates than healthy specimens.It is significant that theproportions of the “ secondary ” nutrients sodium, magnesium,sulphur, and chlorine are not appreciably affected by disease, and,moreover, the recognised treatment (addition of copper sulphateto the soil) results in changes in composition tending to approachthe Similarly, tobacco plants infected with mosaicdisease contain smaller proportions of reducing sugars, disaccharides,starches, and pentosans than healthy plants.24 Investigations of21 D.Ongaro, Atti R. Accad. Lincei, 1931, [vi], 13, 202; A . , 1200.22 K. Boning, 2. Parasite& [Z. wiss. Biol.], 1930, 2, 645; A., 133.21 A. R. C. Haas and L. J. Klotz, HiZgurdia, 1931, 5, 611 ; A., 1201.24 A. A. Dunlap, Amer. J . Bot., 1931, 18, 328; A., 886; compare Ann.Reports, 1930, 27, 240.REP.-VOL. XXKIII. 258 POLLARD AND PRYDE:spike disease reported last year 25 have been extended to Dodomaviscosa by B. N. Sastri and N. Narayana, who record that diseasedplants are characterised by increased contents of sugars and starchesand lowered amounts of calcium.26Problems concerning the effects of fungicides and insecticideson plant growth and composition are tending to indicate in nouncertain manner the need for an extension of the scope of fun-damental research to cover the conditions obtaining in the fieldapplication of these poisons.A prominent instance appears inconnexion with the use of petroleum oils in insecticides. Injuryto plant foliage and fruit from these oils is not always outwardlyvisible, nor is the immediate cause of the injury understood. Themany attempts to correlate physical and chemical properties ofoils with their injurious action seem doomed to failure unless moredefinitely biochemical facts are made clear. Oil injury to foliagebears some relationship to respiratory activity. The work of J.Green and A. H. Johnson2' indicates that oils having more than16% of sulphonatable matter increase, and those with less than16% decrease, respiratory rates of bean leaves.V. W. Kelley,28however, working on deciduous fruit trees, finds that all petroleumoils, irrespective of the degree of purification, reduce respirationrates. The effect is mainly confined to the under surface of leavesand is greater in old than in young leaves. A general discussionof the effects of various grades of oils on the growth of plants isgiven by C. W. Wo~dworth.~~Biochemistry of Moulds.The widespread interest in the growth and metabolism of moulds,which in late years has received such an impetus from the develop-ments in fermentation industries, has again been maintained duringthe year under review.Nutrition.-The apparent selectivity in the assimilation of nitro-genous foods already noted in the case of the higher plants findsits counterpart in the case of moulds.In culture solutions Asper-gillus oryxce 30 can utilise either nitrates or ammonium salts or bothsimultaneously. A predominance of ammonium salts results inretarded growth and the medium becomes increasingly acid. Theaddition of phosphates minimises reaction changes and growth is25 Ann. Reports, 1930, 27, 239.26 J . Indian Inst. Sci., 1930, 13, A, 147; A., 537.2 7 Plant Physiol., 1931, 6, 149; A., 774.2 8 Illinois Agric. Exp. Sta. Bull., 1930, No. 353, 581; A., 1339.29 J . Econ. Entom., 1930, 23, 848; B., 268.3O T. Sakamura, Planta [Z. wiss. Bid.], 1930, 11, 765; A . , 125BIOCHEMISTRY. 259improved. Absorption of nitrate-nitrogen tends to maintain aconstant pH in the medium and both growth and nitrogen intakeare high. The form of nitrogen utilised is also affected by thenature of other constituents, notably the carbohydrates.Nitrateabsorption is favoured by sugars in the order laevulose> sucrose>dextrose. Reaction changes in the medium associated with theassimilation of different forms of nitrogen vary with different speciesof fungus. F. Labrousse 31 shows that Cladosporium cucumerinumand Verticillium dahlice utilise ammonium nitrate and sulphateand produce an immediate acid reaction, but with calcium nitritean immediate alkaline reaction results. With Xclerotinia Zibertianaand 8. minor, the media become increasingly acid as growth proceeds.An extensive and general investigation of this aspect of fungalnutrition is given by K.R i ~ p e l . ~ ~ The enzyme activity of fungiis frequently influenced by the supply of nutrients. G. von Dobyand E. Feher 33 showed that the production of mycelium of Penicil-Eium 'was but little affected by the absence of calcium, but wasmarkedly depressed if magnesium was omitted and ceased entirelyin the absence of phosphates. The increased invertase productionresulting from the addition of sugar to the medium was normal inthe absence of calcium or with a moderately reduced phosphatesupply, but was reversed where magnesium was absent or wherethe phosphate concentration was small. The optimum p H of themedium for invertase production was not, however, appreciablyaffected by the nature of the nutrient salts used.has shown that the effectsof copper, zinc, and iron salts on the growth, pigmentation, andspore production were of a general character for a number of speciesof fungus, although minor varietal differences in the pH, ammonia,and sugar contents of the media are apparent.Aspergillus nigeris reported by W. Schwartz and H. Steinhart 35 to take up a moreor less definite amount of copper in the early stages of growth, a ta rate which is practically independent of the concentration ofcopper in the medium. This copper intake probably represents adefinite metabolic requirement. Stimulative effects of copper,zinc, and manganese on the growth of AspergiZlusJlavus and Rhixopusnigricans are examined by ,J. S. McHargue and R. K. Calfee,36optimum effects being obtained with concentrations of 5-0, 1.0, andEffects of Heavy-metal Salts.-Metz31 Compt. rend., 1931, 192, 980; A . , 768.32 Arch. Milcrobiol., 1931, 2, 72; A . , 1333.33 2. physiol. Chern., 1931, 196, 89; A . , 876.34 Arch. Mikrobiol., 1930, 1, 197; A . , 1094.s5 Arch. Milcrobiol., 1931, 2, 261 ; A . , 1334.36 Bot. Qaz., 1931, 91, 183; A . , 876260 POLLARD AND PRYDE:2.5 p.p.m. of the respective metals. In mixtures of these metalsthe stimulatory action is shown to be an additive function. Allmetals increase the fat and decrease the nitrogen content of themycelium. The assimilation of mineral nutrients by Aspergillusis increased by copper and zinc and decreased by manganese.Tannase.-The ability to utilise tannin as a sole source of carbonis shown only by Penicillium citromyces and Aspergillus, amongmany species examined by A. Rippel and J. KeselingV3' Theproduction of tannase takes place only in the presence of tannin,but is not associated with the power of utilisation of tannin by thefungus. Earlier observations of Nierenstein, that the amount ofgallic acid obtained from gallotannin by means of tannase prepar-ations was less than the theoretical proportion, are now explained 38by the fact that A . niger contains, in addition to tannase, a pyro-gallase which destroys gallic acid. The same organism grown on adextrose-peptone medium is also shown to produce a guanidasebringing about the quantitative decomposition of guanidine tourea and ammonia.39Production of Organic Acids by Fungi.-Factors controlling theproduction of fatty acids by A. niger are examined by C. P~ntillon.~OThe total production of fatty acids is approximately the same inneutral and in slightly alkaline media, but decreases somewhat inacid media. The molecular weight of the acids produced is practic-ally independent of the reaction of the medium, but reaches aminimum a t the period of fructification. The iodine value of theacids produced averages 30 in neutral media, and is slightly greaterin acid conditions. The suggestion of Challenger and others thatsaccharic acid is an intermediate product in the conversion ofdextrose and gluconic acid into citric acid by A . niger is now negativedby K. Bernhauer and H. Siebenauger 41 after examination of numer-ous strains of this organism. Further, when A . niger is grown onsucrose media with minimal amounts of ammonium nitrate, evidenceis advanced by Molliard42 indicating that citric and gluconic acidsare distinct oxidation products of the sugar, citric acid not beingproduced from gluconic acid. Oxalic acid is not formed unlesssodium gluconate or acetate is added to the medium, and in thesecircumstances it is considered to be a definite excretion product.Citric acid production as a function of the reaction of the medium37 Arch. Mikrobiol., 1930,1, 60; A., 1094.38 Biochem. J., 1931, 25, 752; A., 983.39 N. N. Ivanov and A. N. Aretiasova, Biochem. Z . , 1931, 231, 67; A., 524.40 Compt. rend., 1930,191, 1148; A,, 125.4 1 Biochem. Z., 1931, 230, 466; A . , 524.42 Cornpt. rend., 1931, 192, 313; A., 524BIOCHEMISTRY. 261is examined by A. F r e ~ . ~ 3 In Citrmyces gkaber citric acid formationis optimal at pE 3 4 and is inhibited a t pE 2. I n A . niger, optimumproduction occurs at pH 2. I n both cases addition of calciumcarbonate to produce pE 3 - 4 favours the production of the acid.Further neutralisation to produce pH 6.0 increases the formationof gluconic acid from A . niger. I n various acetate media Penicillium(sp. '1) produces succinic, fumaric, oxalic, l-malic, and citric acids,the nature and quantity of the acids varying with the particularacetate provided. Alkali-metal salts favour the formation ofcitric and probably of oxalic acids. The suggested44 mechanismof the production of citric acid from sugars involves the followingsteps : pyruvic acid and acetaldehyde -+ ethyl alcohol + aceticacid + succinic + fumaric -+ Z-malic acids. A parallel ex-amination of the action of A . niger by K. Bernhauer and H. Sieben-auger45 indicates a yield of 16% of citric acid on the acetatedestroyed. Ethyl alcohol, fumaric, malic, and glycollic acids areall converted into citric acid. The production of kojic acid fromtrioses is examined by F. Challenger, L. Klein, and T. K. Walker.46Evidence supports the conception that the formation of the acidfrom pentoses and hexoses occurs via the intermediate breakdownto triose, followed by direct condensation to kojic acid. Theproduction of two new acids by PeniciZEium glaucum on sucrosemedia is reported by N. Wijkman,47 viz., glauconic acid 1, C,,H,,O,,m. p. 202", probably containing one or more lactone rings, andglauconic acid 2, C18H2006, probably tetrabasic.A. G. POLLARD.J. PRYDE.43 Arch. Mikrobiol., 1931, 2, 272; A'., 1333.44 T. Chrzaszcz and D. Tiukov, Biochem. Z., 1930, 229,343; A , , 394.4 5 Ibid., 1931, 240, 232; A., 1333.4 6 J., 1931, 16; A., 625.4 7 Annalen, 1931, 485, 61 ; A., 523

ISSN:0365-6217    

DOI:10.1039/AR9312800212

出版商:RSC    

年代:1931

数据来源: RSC

摘要:

CRYSTALLOGRAPHY,THE past two years have seen a rapid extension of the well-triedmethods of crystal-structure analysis over the whole field ofchemistry, and even beyond it into biological questions. In themetrical structural chemistry of the future it will take its place withthe study of spectra and the optical and magnetic properties ofmolecules. Already the systematic inorganic chemistry, particu-larly for metallic substances, salts, and silicates, needs to berewritten round the data supplied by crystal analysis. At the sametime crystal physics has increasingly succeeded in correlatingphysical properties with crystal structure, and structure withfundamental quantum mechanical relations.An important landmark is the publication of the Strukturberichtof the Zeitschrift f u r Kristallographie.Professor P. P. Ewald andC. Hermann have produced a model of a book of reference. Itcontains in its 800 pages practically all the relevant data that hadappeared in crystal structural work up to the end of 1928. Thearrangement is simple and facilitates reference. It is partlygeometrical and partly chemical. Substances are classified in thefollowing sections : A, element's; B, compounds of type AX;HI, A,(BX4), ; H,, A,(EXk),,.. Then follow : other inorganiccompounds ; L, alloys ; 0, organic compounds.In each section are given, first, detailed descriptions of well-established crystal types, all on a uniform plan with diagrams, notonly of the crystal but of the atomic neighbourhoods, togetherwith numerical data on all crystals of that type.Next followcritical abstracts of all papers on substances belonging to the section,whether they belong to the recognised types or not. The uniformityof the treatment of the very heterogeneous material is of great value,as it enables systematic relations to be seen much more easily thanfrom reading original papers. The only criticism that might bemade is that-inevitably, at the time the work was started-thebasis of classification was not as satisfactory as the present systemsbased on crystal chemistry. Metallic compounds are found, forinstance, scattered through many of the classes, and the relationsbetween the different silicate structures are concealed. This wouldbe of little importance if the very existence of the Strukturberichtdid not tend to make the type symbols, e.g., B, for sodium chloride,H,, for spinel, etc., pass into general use.c, AX,; D, AmX,; F, Am(XY), or A,(XYZ),; G, Am(BX,)nCRYSTALLOGRAPHY.263Wyckoff’s second edition of his “ Structure of Crystals ” gives usan up-to-date English text-book of the subject which has been badlyneeded. The first part deals with the technique of the analysis ofcrystals and contains adequate and critical descriptions of the chiefmethods used. It would have been better if the arrangement ofthe first edition had not been so closely followed. The second part,dealing with the results of structure analysis, is admirable. Nodetail is attempted, but the essential features of every importantstructure are brought out and emphasised by clear and beautifuldrawings.The complete bibliography up to the end of 1930 is alsovery valuable.The second edition of Wyckoff’s “ Analytical Expression of theResults of the Theory of Space Groups ” contains some usefulperspective drawings of symmetry elements. Meyer and Mark’s“ Der Aufbau der Hochpolymeren Organischen Naturstoffe ’’ isreviewed in another section of this report.Nomenclature of Space Groups.-In 1930 a committee of theInternational Congress (see Ann. Reports, 1929, 26, 276) metin Zurich.l Here it was decided to set in hand the preparationof International Tables for Crystal Structure and to arrangefor the publication of standard abstracts according to therecommendation of a sub-committee.2 For both these purposes anagreed notation for symmetry elements, crystal classes, and spacegroups was needed.The committee finally agreed on the Hermann-Mauguin notation. This is a rational system of notation putforward in principle by C. Hermann and subsequently simplifiedby Ch. Mauguin.4 As it is likely to be widely if not universally usedin the future, the following brief account of it is given.I n this notation the minimum elements of symmetry needed todevelop the group are directly symbolised instead of being enumer-ated as in older systems. I n each symbol the first place is takenby a capital letter standing for the lattice type : P stands for aprimitive lattice, A , B, C for lattices face-centred on the (loo),(OlO), (001) face respectively, I for body- (inner) centred, and Ffor face-centred lattices.The rhombohedra1 lattice is designatedby R, and the hexagonal by C or H according as the crystallographic.axes coincide with or are perpendicular to the primitive translationsof the lattice. Next follows the notation for the elements ofsymmetry : 1, 2, 3, 4, 6 for axes of simple rotation; 1, 3, 3, 6 foraxes of rotation-inversion ; and 2, ; 3,, 3, ; 4,, 4,, 4, ; 6,, 6,,6,, 6,, 6,-2. Krist., 1930, 75, 159.J. D. Bernal, P. P. Ewald, and C. Mauguin, ibid., 1931, 79, 495.Ibid., 1928, 68, 257; 1929, 69, 226, 250, 533; 1931, 76, 559.Ibid., p. 529264 BERNAL AND WOOSTER :for screw axes. 1 indicates asymmetry, 1 a centre of symmetry;2 would indicate a symmetry plane, but owing to their specialimportance planes of symmetry are designated by letters : m standsfor a reflexion plane, other letters for glide planes, a, b, c for glideplanes with 8 translation parallel to the a, b, c axes, n and d for one-with 8 or & translationrespectively, parallel to [Oll], [loll, or[110].The symmetry of any space group can be designated in terms ofthese elements only by using an invariable order.First comes thelattice symbol P, A, B, C, I, F, R, or H ; next follows the symbol ofthe principal axis (except in the orthorhombic holoaxial class, wherethe arbitrary order a, b, c is followed, and in the holohedral class,where plane symbols are used instead). If there is a plane ofsymmetry perpendicular to this axis, it follows it immediately,separated by an oblique rule /, e.g., 2/m for monoclinic holohedry.Next follow the secondaryaxes or planes with the convention thatan axis symbol is only put when there is no corresponding planeperpendicular to it.Thus the holohedral classes are designatedby : Ci - T, C 2 h - 2/m, V , - mmm, D4h - 4/mmm, D3,, - 3m,Da - 6/mmm, o h - m3m (the cubic system is always characterisedby 3 in the second place).The different space groups of any crystal class are distinguishedby the different notations for glide planes and screw axes.The great advantage of this notation is that each space groupsymbol gives all its symmetry elements without recourse to memoryor tables. It is particularly valuable to X-ray workers, because bythe use of a few simple rules the space group symbol can be writtendown direct from observed absent reflexions, and from the symbolthe co-ordinates of the equivalent points can be written down.I n accepting this notation at the conference, it was decided thatin order to preserve historic continuity it should be used in conjunc-tion with the Schoenflies notation for a period of years, as, e.g.,Vi6 - Pnma, O9 - Im3m.-CRYSTAL PHYSICS.Since the last Report on this subject in 1929 there have beennotable advances in nearly all its branches.Here only three willbe dealt with, vix., the growth and solution of crystals, liquidcrystals, and the relation between optical properties (including theRaman spectra) and structure. This somewhat arbitrary limitationis rendered necessary by the rapid developments which have beentaking place, and it has been thought better to deal fairly fully with8 few subjects rather than very shortly with them allCRYSTALLOGRAPHY. 265Growth, Volatilisation, Melting, and Xolution of Crystals.Investigations into the growth, volatilisation, melting, andsolution of crystals have been pursued for many years, and thisReport includes work carried out before 1929. In order to give asclear an idea as possible of this extensive and involved subject it istreated under the following headings : crystallisation in vapours,melts, solids, and solutions.Each of these four divisions is againsubdivided into three main parts, vix., the formation of nuclei,crystallisation, and volatilisation or melting or solution.The conditionsgoverning this phenomenon are but little known.Nuclei are formedwhen a sufficient degree of supersaturation is reached, but what thatis in any particular case, and what determines it, isThe growth of crystals in a vapour is found tobe influenced by (a) temperature of formation, ( 6 ) vapour pressureof the gas at the temperature of growth, (c) presence of other gases,( d ) orientation of the crystal with respect to the direction of flowof the vapour, ( e ) preferential directions of growth, (f) size of crystals.Although in most of the experi-ments mentioned below no direct measurements of this quantityhave been made, its influence on the formation of crystals may tosome extent be estimated from the following facts.prepared single crystals of tungsten by decomposing the gaseoushexachloride at 110" with a tungsten filament a t 1000".M. Piraniand W. Fehse produced graphite by decomposing substituted andother hydrocarbons with a glowing carbon filament heated to1500-2000"; A. E. van Arkel and J. H. de Boer 8 prepared puretitanium, zirconium, hafnium, and thorium by heating a tungstenfilament to 2000" in the pure vapours of the metallic tetraiodides,and also the carbides and nitrides of these metals by decomposingthe chlorides in the presence of small quantities of gaseous carbonand nitrogen compounds respectively. E. Sutter produced crystalsof a-, y-, and S-iron by decomposing a mixture of ferric chloridevapour and hydrogen by means of a tungsten or iron wire heatedto the appropriate temperature.M. Straumanis 10 found that thebest crystals were produced when the vapour of zinc or cadmiumcondensed on a surface a few degrees below the melting point.(6) Vapour pressure of the gas at the temperature of growth.Van Arkel and de Boer used their metallic iodides at atmosphericpressure, but Koref obtained a more coherent deposit, whoseIbid., 1923, 29, 168.Crystallisation in Vapours.-Fmmution of nuclei.Crystal growth.(a) Temperature of formation.F. KorefM. Volmer and A. Weber, 2. physikal. Chem., 1926, 119, 295.2. Elektmchem., 1922, 28, 511.2. anorg. Chem., 1925, 148, 345. 9 Diss., Groifswald, 1927.lo 2. physikal. Chem., 1931, [B], 13, 316.I 266 BERNAL AND WOOSTER :crystals were single, if the vapour pressure of the tungsten hexa-chloride-hydrogen mixture was at 12 mm.of mercury. Thetemperature of the chamber was 110" and the boiling point of thehexachloride is 347". also found thatlow pressures favoured the growth of large crystals, better graphitecrystals being obtained a t a pressure of 2 mm. of carbon tetrachloridethan at pressures up to 25 mm. Straumanis lo concluded that ahigh density in the atomic stream favoured the growth of largecadmium and zinc crystals. (Miss) C. P. Elam l1 prepared crystalsof a-, p-, and y-brass from copper by heating it in the vapour ofzinc. Which compound of brass was formed depended on thetemperature and vapour pressure of the zinc.I n Koref's experiments, hydrogenseemed to have no influence on the deposition of crystals, but vanArkel and de Boer found that because of chemical action anycompound of carbon or nitrogen inhibited metallic depositionentirely.I n general, it appears that inert gases hinder the distill-ation of a volatile solid from one part of the container to another.P. Kapitza l2 found that bismuth formed an amorphous depositwhen distilled on a cold surface, but a crystalline one on a hotsurface. The same phenomenon was observed long ago whenfilms of bismuth, silver, and gold were spluttered on to glassplates. l3(d) Orientation of the crystal with respect to the direction of theflow of the vapour. M. Volmer l4 distilled a beam of zinc atoms,allowing them to impinge on an inclined glass plate.He showedthat the crystals oriented themselves, the (0001) plane growing withits normal parallel to the beam. This was also observed withcadmium atoms. Straumanis l o found that the basal plane in zincand cadmium was usually parallel to the surface of the glass tubeon which they were grown. In Koref's experiments the orientationof the tungsten crystal was determined solely by the original orient-ation of the core. Pirani and Pehse found that the graphite crystalsinvariably grew with the normal to the basal plane perpendicular tothe rod.M. Volmer and I. Ester-mann15 condensed the vapour from mercury a t - lo", in theabsence of inert gases, on a surface a t - 63". Small hexagonalplates parallel to (0001) were formed, 10,000 times as wide as theyM.Pirani and W. Fehse(c) Presence of other gases.(e) Preferential directions of growth.l1 J . Inst. Metals, 1930, 43, 217.13 J. Patterson, Phil. Mug., 1902, [vi], 4, 652; J. A. Becker and L. F.Curtis, Physical Rev., 1920, 15, 457; F. K. Richtmyer and L. F. Curtis, ibid.,p. 465.Proc. Roy. SOC., 1928, [ A ] , 115, 358.l4 2. Physik, 1921, 5, 31. Ibid., 1921, '7, 13CRYSTALLOGRAPHY. 267were thick. When about 0-3 mm. across, they fluttered down.The enormous disparity in the dimensions shows the power of thedirective crystalline effect. The theory advanced to explain theunexpectedly rapid rate of growth is that mercury atoms impingingon the plate did not bounce off, but wandered over the surface,increasing the number of atoms which could become attached tothe edges of the growing plate.This marked directional effectseems to be exhibited more strongly in crystals grown from vapoursthan in those from melts and solutions. In the Reporter's (W. A. W.)own experience, sublimed crystals of naphthalene, CrCl,, FeCl,,AlCl,, MOO,, AsI,, SbI,, and BiI, all occur in very thin plates, whereasfrom the melt or solution the tendency is for them to occur in moreequally developed forms. Zinc and cadmium also grow in thinhexagonal plates, the step-like surface of which shows that theyhave grown from the inside outwards. Observations on crystalsgrown from melts and solutions suggest that their growth starts a tthe edges and spreads inwards.Koref observed that after the single crystal-line rods, obtained by decomposing tungsten hexachloride vapour,had reached a certain diameter they ceased to grow as single crystals,small ones growing on the sides in random orientations. Size playsso important a r6le in growth from fusion that it seems likely thatmuch remains to be discovered on the effect of size on crystallisationfrom the vapour.Volatilisation.G. Aminoff l6 has shown that crystals of thymol,ammonium chloride, a-sulphur, etc., show preferential directions ofvolatilisation. Spheres were allowed to evaporate and the resultingfacets photographed. Straumanis lo has investigated the details ofthe process in cadmium by lowering the vapour pressure in the vesselin which cadmium crystals have been growing. Pits developed inthe basal plane similar to the etch pits obtained by solution, andshowed the same characteristic thickness of step observed on theedges of crystals grown in the vapour.Crystallisation and Solution in Melts.-Formation of nuclei.Whereas some substances crystallise from a melt very readily,others may be supercooled and remain amorphous for an indefiniteperiod.The origin of the nuclei from which the crystals arise hasled to much speculation and experimental work. Some crystallinesubstances when raised just above their melting points and thencooled recrystallise readily, but if heated to a considerably highertemperature they cam become supercooled before crystals reappear.This would suggest that nuclei can persist in an apparently fusedsubstance, a supposition supported by the theoretical work of(f) Size of crystal.l6 2.Rrist., 1926, 61, 373; 1927, 65, 23268 BERNAL AND WOOSTER :R. Bloch, Th. Brings, and W. Kuhn.17 L. Graf l8 found it neces-sary to heat copper, silver, and gold about 150" above their meltingpoint in order to get good single crystals, free from small disorientedones. E. Scheil,lg A. Goetz,2* and A. G. Hoyem and E. P. T.Tyndall 21 have found a similar treatment necessary in preparingcrystals of aluminium, bismuth, and zinc. After cooling below themelting point, crystallisation may be induced in various ways. Asharp blow with a hammer on an anvil can induce it just below themelting point in water, benzene, and fused hydrated calciumchloride.22 Scratching the inside of a vessel containing a super-cooled liquid with a glass rod is known to promote crystallisation,also exposure to air, or impregnation by dust particles.Hoyem andTyndall 21 found that in growing single crystals by gradually drawinga rod out of the melt, other crystals arose with a random orientationunless the surfaces were kept free from impurities. Although theReporter can find no account of it, it seems probable that crystallineparticles of isomorphous substances act as nuclei when put into asupercooled melt. H. Pollatschek 23 found that salol crystallisedmore rapidly in a copper than in a glass tube, under similar condi-tions of supercooling, so that measurements on the rate of crystal-lisation could not be made in the former.A common practice atthe Geophysical Laboratory, Washington, when dealing withartificial silicates which prove very slow in crystallising, is to takethe glass which results on cooling the melt, pound it to a fine powder,heat it, and cool it, and repeat the whole process many times. Thisapparently accelerates the rate of crystallisation. There is ananalogy here with the cold working of metals which must be per-formed before a polycrystalline material can be made to recrystalliseas a single crystal. The pounding of the glass or the shaking ofviscous liquids may be methods of setting up strains which pre-dispose them towards crystallisation. W. Kondoguri 23a has inves-tigated the increase in the number of nuclei formed in a given timedue to the application of an electric field to crystallising salol andpiperine.Growth. The factors which influence the growth of crystals froma melt are : (a) temperature gradient at the surface of the crystal,( b ) thermal conductivity of the solid, (c.) viscosity of the melt--degree of supercooling, (d) impurities , including dissolved gases,(e) state of strain in solid, or a magnetic field, [f) relative sizel7 2.physikal. Chem., 1931, [B], 12, 415.2. Physik, 1931, 67, 400.2o Physical Rev., 1930, 35, 193.22 5. Young and W. van Sicklen, J . Amer. Chem. SOC., 1913, 35, 1067,23 2. physilcal. Chem., 1929, 142, 289.23a 2. Physilc, 1928, 47, 589.lo 2. Metallk., 1929, 21, 124.'21 Ibid., 1929, 33, 84CRYSTALLOGRAPHY. 269parallel and perpendicular to the direction of growth, (9) specificcharacters of crystal directions.F.Stober 24 has shown that in order to get large flawless crystals ofsodium nitrate from a fused melt, it is necessary to adjust thetemperature gradient near the surface of the growing crystal verycarefully.Ideadly, the isothermal surfaces are made parallel to thecrystal surface, and the crystallisation front advances at the samespeed as the isotherms. To enable this to happen, the temperaturegradient is maintained a t such a value that the liquid near thecrystal is as mobile as possible, since the velocity of crystallisationfalls with increasing viscosity [see (c), below]. P. Kapitza l2 foundin growing bismuth crystals from the melt that a strong temperaturegradient was required perpendicular to the (1 1 1) plane if the crystalswere to be flexible. A theory on the rate of crystallisation in itsrelation to the thermal constants of the solid and melt, and thetemperature gradients, has been given by H.P~llatschek.~~In a discussion of theattempts to make artificial diamonds, Stober points out thatMoissan found it necessary to cool the iron containing the carbonvery rapidly, whilst other workers using silicate melts had to givecooling periods of the order of weeks. This difference he attributesto the different thermal conductivities of iron and silicates. Bothrequire the temperature gradient a t the surface of the growingcrystals to be great enough to prevent the melt becoming too viscous.The outside of the iron must therefore be cooled to set up thisgradient, whilst it arises only too easily in the silicates.(c) Viscosity of the melt.If the melt becomes too viscous, thecrystallisation becomes slow. If the supercooling is large and atthe same time rapid, the melt may solidify to a glass. The rateof growth plotted as a function of the temperature in pure glycerol 26gives a curve starting from zero a t the melting point, rising t'o amaximum about 10" below this temperature, and then falling againto zero.(d) Impurities, including gaseous inclusions. Stober 27 foundthat a growing single crystal had the remarkable property of rejectingimpurities. Copper and glass spheres dropped on a crystal of sodiumnitrate, growing in a crucible from the bottom upwards, were pushedu p by the crystal surface as it rose.This also occurred with theminute air and water bubbles which are always present when thecommercial product, is melted. When the melt was saturated with24 2. Kriat., 1924, 61, 306.26 M. Volmer and M. Marder, ibid., 1931, 154, 109.27 Chem. Erde, 1931, 6, 357.(a) Temperature gradient a t the surface of the crystal.(b) Thermal conductivity of the solid.Probably this is typical of many melts.25 2. physikal. Chem., 1929, 142, 289270 BERNAL AND WOOSTER :quartz grains, these could not be ejected and a single crystal grewround them, with a texture closely simulating t,hat of Pontainebleausandstone. The same power of ejecting impurities is found inbenzophenone,28 when it is contaminated with certain dyes.Thecrystals grow quite colourless if the crystal is allowed to grow inopt'imum conditions, but if the degree of supercooling is increasedtthe dye is taken up by the crystal quite regularly, giving rise topleochroism. The mixture can show " Entmischung," the dyeseparating out as inclusions, leaving the crystal body clear. It hasbeen suggested that the flexibility of bismuth crystals dependsupon the amount of impurity, but Kapitza has shown that singlecrystal rods of bismuth may be flexible in one half and brittle inthe other, the temperature gradient atl the growing surface beingthe determining factor.12 Graf,1* on crystallising copper, foundthat the following impurities were not ejected : 0.4y0 copperoxide, o.03~0 sulphur, 0.027; iron, but that they were uniformlydistributed through the crystal.P. W. Rridgman 29 found thatgaseous impurities had a bad effect on the growth of metal crystals,but Graf 18 obtained the same crystals of copper, silver, and goldwhether he grew them in a vacuum or in an inert gas. Hoyem andTyndall 21 found on preparing single crystals of zinc (containing0-000025~0 As, 0.028y0 of matter oxidisable by permanganate asFe, and 0.0020% of chlorides) by withdrawing a rod from the melt,there was a tendency for particular orientations to change gradually,whereas with a purer metal (0~0000250/, As, 0.0056% of matteroxidisable as before) the change was sudden.From these examples it is clear that we must distinguish betweentwo types of impurity, those which can accommodate themselves tothe lattice, and are taken up in solid solution, and those whichcannot be taken up in this way, c.g., oxygen in aluminium.Thiskind of impurity tends to be pushed out of the crystal as it grows,but if the viscosity of the melt is too high, or the volume of theimpurity too great, this becomes impossible, and the impuritybecomes embodied in the crystal.(e) State of strain in the solid, and the effect of a magnetic field.Hoyem and Tyndall 21 inoculated molten zinc with a single crystalof known orientation and proceeded to withdraw it as a singlecrystal rod, keeping the rate of withdrawal and the temperaturegradient above the level of the molten zinc constant. They foundthat the bath of zinc had to be kept within a small range of tem-perature if the orientation was to remain the same throughout thewithdrawal, for beyond the limits of this range the direction of the28 G.Tammann and E. Laass, 2. anorg. C'Jaem., 1928, 172, 65.29 Proc. Amer. Acad., 1925, 80, 305CRYSTALLOGRAPHY. 27 1hexad axis changed through about 50°, independent of the orient-ation of the seed crystal. Their conclusion, that ‘‘ the temperaturegradient existing in the liquid zinc just before it solidifies is the mainfactor determining the contlinued and successful growth of a par-ticular orientation,” seems to be unproven, since they did notinvestigate other possible influences, such as change in the rate ofwithdrawal. It appears likely that it may be due to the zinc glidingon the basal plane, the temperature having a secondary effect bycontrolling the weight of the just solidified portion.The observ-ations are analogous to those made by Kapitza,12 who found itimpossible to grow a crystal of bismuth with its (111) plane per-pendicular to its length if it were subjected to the slightest strainwhile cooling. A. Goetz30 has investigated the effect of growinga part of a single crystal of bismuth in a ma,gnetic field. The twohalves of the crystal show different densities and specific resistances.(f) Relative size parallel to the direction of growth and perpen-dicular to it. F. Stober 3l brings forward much evidence to showthat the rate of growth in a particular direction is inversely propor-tional to the area of a perpendicular cross-section.A quantitativetest of this assumption was made on crystallising sodium nitrate.By slow cooling, the whole content of a nickel crucible could bemade to grow as a single crystal, with its optic axis perpendicularto the isotherms. More rapid cooling caused the growth of anumber of parallel rods, having the same orientation as the singlecrystal. The average area of the rods varied approximately as theinverse of the time taken over cooling. Stober applied this relationto some hitherto unexplained results obtained by other workers.32Another application of this principle is to be found in the rapidrates of growth often seen in crystals which form needles, thinplates, and sheaf-like growths. In attempting to explain the relationbetween rate of growth and area of growing face, Stober seems tobe on less certain ground.He assumes that the gravitationalattraction which one atom exerts on an approaching atom isprimarily responsible. The gravitational field near to a single rowof atoms must be periodic and may possess marked directive proper-ties. These are very much less a t the surface of an actual crystalbecause the atoms in the body of the crystal smooth out thevariations in the forces produced by the single row of atoms. Simi-larly, the greater the area of a face the less is the force of attractionexperienced by an atom approaching the face. On this ground30 Physical Rev., 1930, 34, 193; 35, 193; 36, 1752.31 Chern. Erde, 1931, 6, 453; Jahrb.Min., Bed.-Bd., [ A ] , 1928, 57, 156.32 M. Volmer and G. Adhikari, 2. Physik, 1925, 35, 170; F. Bernauer,Jahrb. Min., Bed.-Bd., [A], 1928, 57, 1131272 BERNAL AND WOOSTER :Stober attempted to explain why slowly cooled sodium nitrategrows as a single crystal whilst the rapidly cooled melt forms narrowcrystal rods. This explanation can scarcely be correct because ofthe enormous disparity between the crystal and atomic dimensions.It can hardly make any difference to the gravitational forces a t theface of a growing crystal whether it is a millimetre or a centimetreacross. But if every new layer of a growing crystal had to start ata corner or edge and then travelled inwards, a crystallisation frontwould be able to advance more rapidly if the number of edges andcorners were increased by the decrease in the area of the individualcrystals.(Sir) H. Miers 33 suggests that the crystal itself and theparticles about to be deposited are in mechanical resonance. Werethis so, then the characteristic frequency of a large crystal wouldbe low and might correspond to a slow rate of deposition, thusaccounting for Stober’s empirical result.All substances whichcrystallise as needles or plates do so with a definite relation to thecrystal axes. Stober 34 suggests that the crystallisation front ofsodium nitrate is always perpendicular to the optic axis because itis the direction of greatest heat conductivity. It would be valuableto establish this relation for other crystals. Whilst this type ofexplanation gives an indication of the direction of elongation, thereason why some crystal faces appear rather than others remainsobscure, and, at present, we cannot do more than attribute to eachface a specific rate of growth.(h) The process of melting.The study of the behaviour of crystalfaces during melting is made very difficult by the immediatesolidification of some of the adhering liquid on removing it fromthe melt. The X-ray method used by A. Miiller 35 is very powerful.A fine beam of X-rays was directed on some molten paraffin verynear the surface of a, crystal of the same substance. For a smallrange of temperature above the melting point, the diffractionpattern showed that there was still a considerable amount oforientation among the molecules. Apparently the crystal dissolvesin sheets of molecules.A similar orientation of the molecules of aliquid near to a solid surface is well brought out in the experimentsby J. J. Trillat.36Growth of Crystals in the Solid State.-An immense literature hasgrown up during the last few years on the recrystallisation of solids,but it is principally concerned with problems of strain and mechanical(9) Specific characters of cryst’al directions.33 Science Progress, 1907. 34 Chem. Erde, 1931, 6, 440.35 Proc. Roy. SOC., 1930, [A], 127, 417.s6 See summary, “ Fortschritte der Rontgen Forschung,” p. 33; Akad.Verlag. Ges., Leipzig, 1931CRYSTALLOGRAPHY. 273properties in metals. This Report does not include this work except&s illustrating particular features of solid recrystallisation which aredealt with here.References to a few papers dealing with therecrystallisation of metals are given.37Nuclei for recrystallisation do not ariseunless the material has been strained to some extent; generallyonly a small deformation is required. In some cases they may belatent, as they may not develop for hours after other nuclei havegrown into grains of considerable size. The rate of formation ofnuclei for a given degree of deformation is higher the higher thetemperature. The presence of impurities generally facilitatesnucleus 'formation.The conditions which appear to affect the growth of analready formed nucleus ere : (a) temperature, ( b ) impurities,(c) orientation of neighbouring grains.The size of the crystal seems to have no effect on the growth,contrary to what one might expect, since it influences growth frommelts and vapours.38(a) Temperature. Tammann and Dreyer 38 have investigatedthe effects of cold working and subsequent heating on camphor,pinene hydrochloride, and ice.The substances were compressedto about a quarter of their original thickness and then annealed a tvarious temperatures. The more powerful the compression and thenearer the annealing temperature lay to the melting point the greaterwas the rate of advance of the crystal grain boundaries. The samegeneral result has been found to hold good in metals. Apparentlythe rate of recrystallisation tends to infinity as the temperatureapproaches the melting point.The limit is set by the impuritieswhich the crystal has to push out of the way.Most work on the recrystallisation of metalsshows that large single crystals can only be grown in pure substances.A considerable quantity of impurity not only causes spontaneousgrowth from many centres but appears to hinder the growth of thegrains by forming a kind of skin round the boundary of the grow-ing crystal. The existence of these skins was demonstrated byTammann and Dreyer : distillation of the substances from the plateafter the recrystallisation left a fine residue outlining the boundariesof the crystal grains, the rest of the plate being quite clean. Theskin formed round metal grains may be similarly demonstrated bydissolving away the metal without evolution of gas.This expulsions7 G. Tammann, 2. amrg. C h n . , 1930,185, 1; A. E. van Arkel and J. J.A. Ploos van Amstel, 2. Physik, 1930, 62, 43, 46; W. G. Burgers, ibid., 1930,59, 651 ; U. Dehlinger, Ann. Physik, 1929, [v], 2, 749.sB R. Karnop and G. Sachs, 2. Phyaik, 1930, 80, 464; G. Tclmmann andK. L. Dreyer, 2. anorg. Chem., 1929, 182, 289.Formation of nuclei.Growth.( b ) Impurities274 BERNAL AND WOOSTERof impurities is not surprising since the same phenomenon is foundin the growth of crystals from melts. This may give the key to thespontaneous growth of crystals after deformation, which, causingthe grains to slip along certain planes, breaks the skins of impurities,and allows the pure material of one grain to come into contact withthat of another.37 A less deformed crystal can then proceed togrow at the expense of a more deformed one.This expulsion ofimpurities may also be able to account for Schiller structures,observed in various minerals. Under the microscope they are seento consist of orientated, regularly-shaped inclusions, bounded bycrystal faces. They are usually attributed to a change in com-position on cooling (“ Entmischung ”), the components whichseparate out taking up their position in cracks previously dissolvedout by magmatic solutions. In the light of the facts given above,it appears more probable that the original crystal suffered a strainand, in consequence, broke up into a much finer grained material.Subsequent cooling caused “ Entmischung ” to occur, and therejected components were thrown out as insoluble material.Duringrecrystallisation that followed the straining (which would be facili-tated by a rise in temperature, but could take place slowly withoutit), the impurities would migrate to the boundaries of the grainsand there crystallise out. The regularity o€ the inclusions is to beexplained by the known regularity of the glide planes produced bypressure. The homogeneity of the matrix is due to the recrystal-lisation after the ejection of the impurities. A similar explanationmay also apply to the calcium-rich minerals such as epidote zonallyarranged in recrystallised albite. Deformation may also be pro-duced by y-radiati~n,~g and recrystallisation in sodium chloridethen occurs at room temperatures.Przibram has taken cine-matograph photographs of large grains being produced during therecrystallisation.Tammann and Dreyernotice a very marked tendency in crystals of camphor and ice forthe basal plane, if suitably oriented, to grow a t the expense of allother planes. The great advantage of experimenting with trans-parent doubly refracting crystals is apparent here, a similarinvestigation in metals being far more difficult to carry out.Growth from and Solution in Solvents.--Formation of nuclei. Whenthe supersaturated aqueous solution of an inorganic salt (e.g., sodiumnitrate) is cooled, a temperature is reached a t which it is possibleby inoculation to cause crystallisation. At the same concentration,crystallisation may also be induced by other methods, such as violentshaking, scratching the side of the vessel with a glass rod, violentss K.Przibram, 2. Elektrochern., 1931, 37, 535.( c ) Orientation of neighbouring grainsCRYSTALLOGRAPHY. 275impact, etc. Although other workers have contradicted his asser-tion, it seems probable from the work of Miersm that there isa maximum temperature (about 10" below the first temperatureat which it is possible to cause crystallisation by inoculation) atwhich the solution if left quite alone will crystallise spontaneously.The long controversy which has continued over the existence of the" supersaturation temperature " for a given concentration cannotbe more than mentioned here. If the saturated solution be inocul-ated with an isomorphous substance, crystals can be caused todeposit on this as nucleus, but the degree of supersaturation requiredis dependent on the kind of nucleus ~ s e d .~ 1 The same phenomenonhas been shown by M. Volmer and A. Weber,42 who investigatedthe degree of supersaturation required to cause crystals of oneinorganic salt to grow on various insoluble substances. Theymention that sodium nitrate tends to grow on the edges of calciteand that the side faces of barytes, gypsum, and mica cleavage plateswere active in precipitating this salt. I n some cases the depositionof foreign nuclei is clearly subjected to a directive force, e.g.,potassium iodide on muscovite, cyanite on staurolite, potassiumchloride on rock-salt.Growth. The conditions governing the growth of a cryshal fromsolution are : (a) temperature, as it affects the degree of super-saturation, (b) impurities in the solution, ( c ) size and shape of thecrystal, and effect of surrounding faces, (d) specific characters ofcertain crystalline directions.(a) Temperature as it affects the degree of supersaturation.Following the general reasoning applied to many physicochemicalproblems, the rate of increase of the distance x between two parallelfaces on a crystal has been shown 43 to be given approximately bythe formula dxldt = k(c - co)> where c is the prevailing concentrationa t time t, and c,, is that corresponding to equilibrium between saltand solution.The habit of the crystals has been observed tochange with the degree of super~aturation.~~ In addition tochanging the degree of supersaturation, temperature must alsochange the viscosity, but the effect of this on the rate of growthdoes not appear to have been investigated.The influence on the crystal habitof impurities dissolved in the solution has been known in certaincases for a very long time.The work of H. E. Buckley 45 ha.s( b ) Impurities in the solution.40 Inst. Metals, May Lecture, 1927.*l I. N. Stranski and K. Kuleliew, 2. phyeikal. Chem., 1929, 142, 467.42 Ibid., 1926, 199, 277.43 M. le Blanc and W. Schmandt, ibid., 1911, 77, 614.44 A. Shubnikov, 2. Krist., 1914, 53, 433.45 Ibid., 1930, 73, 443; 75, 15; 76, 147; 1931, 78, 412; 80, 238276 BERNAL AND WOOSTER :shown how extensive and remarkable these effects are with a largenumber of inorganic salts. He has also attempted a correlationof the lattice dimensions on the crystal faces whose growth rates aremost affected by the impurity and the atomic distances charac-teristic of the dissolved ionic impurity.Progress in this subject isnot easy, and there are few cases where such a correspondenceexists. I. Kurbatov46 has shown how the occurrence of largecrystals, particularly of sparingly soluble substances, e.g., barytes,may be explained by the occurrence of supersaturated solutionsof barium and sulphate ions in non-equivalent proportion. Thisstate is established by soluble impurities. Frl. Buschendorf 47 hasdescribed an occurrence of fairly large crystals of barytes whichmust have grown during historical times, and an analysis of thesolution in which the crystals occurred showed that it containedbarium, calcium, iron, carbonate, and sulphate ions.The mechanism by which a change in habit is brought about bydissolved impurities is still obscure.The theoretical work ofW. Kossel 489 49 and I. N. Stranski 50 indicates that, as in the caseof crystallisation from melts, each new layer has to start a t a corneror edge and then spreads across the face at a great speed. Thetime taken in crystallisation thus depends on the probabilityof a new set of atoms being oriented at a corner or edge. If animpurity be introduced, and this adheres to the growing surface, itis clear that the rate of spreading of the layers across the surfacewill be impeded by the presence of the foreign ions.This processis well illustrated by the case of rock-salt and urea. The occurrenceof the octahedral face in the former means that this is slower growingthan the cube. Since the octahedral face in rock-salt contains onlynegative or positive ions, it is to be expected that a polar bodylike urea will be more likely to become attached to this face thanto the cube face with its mixed ions. This would cause the (111)faces to have a rate of growth slower than normal, and to be pre-dominant in a crystal grown in such a solution. The absorptionof dyes on the surfaces of growing crystals 5l shows that theimpurity is very closely associated with the surface during growth.( c ) Size and shape of the crystal, and the effect of surroundingfaces.M. Bentivoglio 52 has shown that the rate of growth ofseveral crystals, including the double sulphates of the generalformula R',R"(SO,),,GH,O, is, over a range of 0.3-6.0 mm., inde-4 6 A. Shubnikov, 2. Krist., 1931, 77, 164; A., 677.4 7 Centr. Min., 1930, 467.49 Naturwiss., 1930, 18, 901. 50 2. physikal. Chem., 1928, 136, 259.51 T. S. Eckert and W. G. France, J . Arner. Ceram. SOC., 1927, 10, 579;62 PTOC. Roy. Soc., 1927, [ A ] , 115, 67.Nach. Ges. WGs. GBttingen, 1927, 135.F. G. Keenen and W. G. France, ibid., p. 821CRYSTALLOGRAPHY. 277pendent of their size. Certain inorganic salts, such as the alums,Rochelle salt, potassium ferrocyanide, etc., can be grown t o verylarge crystals, and it seems that there could not be much reductionin the rate of growth for a given amount of supersaturation, for if SOthey could not grow to this extent with such rapidity.The shapeof the crystal is determined by the fact that it tends to be boundedby the slowest-growing faces, and the rate at which these developis, according to Bentivoglio, not affected by other faces which maybe present except when the latter develop so rapidly that theyimpoverish the solution surrounding the more slowly-growing faces.K. Spangenberg 53 and A. Neuhaus s4 have shown that for variousalums and for rock-salt the rate of growth for a given form dependson what other forms are present. If other faster-growing forms arepresent, the form grows more slowly than when the other forms growmore slowly.In spite of the careful mewurements of the aboveauthors, one is compelled to remember that under other conditionswhere the supersaturation is greater the rate of growth of faces ofthe same form is not the same for all faces of that form. Forinstance, potassium chloride crystallising from a supersaturatedsolution on a microscope slide almost invariably shows some crystalswhich have grown into long needles, bounded by the cube facesonly. Potassium permanganate crystallising slowly grows equably,but from a drop on a microscope slide it often crystnllises in a massof fine needles. It is very dif5cult to understand how a cubiccrystal can have a different rate of growth for two faces of the cubicform, under identical conditions.* One of the most importantobservations that remain to be made is the variation of the con-centration gradients over different faces of a cubic form when theyare growing a t different rates.(d) Specific characters of certain crystalline directions.Anexplanation of the action of urea on the habit of rock-salt has beenattempted in terms of the different solubilities of the cubic and theoctahedral faces. Such an explanation was dismissed by theexperiment of F. G. C ~ t t r e l l , ~ ~ who showed that an octahedron of53 Juhrb. Min., Bei1.-Bd., [A], 1928, 57, 1197.64 2. Krist., 1928, 15.5 5 Min. Mag., 1908, 15, 39.5 6 J. PhysicaZ Chem., 1906, 10, 52.* (Sir) H. Miers 56 suggests that the needle-shaped crystal is due to thesolution’s being in the labile state, i.e., at a concentration such that it canproduce nuclei spontaneously. He considers that the needle advances con-tinuously into a labile region of the solution, and that the sides which do notgrow are surrounded by a layer of metastable liquid.It is difjficult to under-stand how this can be the explanation, because these same quiescent sidesstrtrt to grow in this supposedly metastable region as soon as the end of theneedle ceases to grow rapidly278 BERNAL AND WOOSTERrock-salt grown from a urea- bearing solution remained unaffectedwhen immersed in a pure solution of salt saturated at the same tem-perature. Stranski and Kuleliew,41 in investigating the depositionof sodium nitrate on the isomorphous substances calcite, siderite, andrhodocrosite, found that the nitrate crystals deposited first a t thecorners and then a t the edges.Deposition in the middle of therhombohedra1 faces occurred last of all, and then only in cracks orirregularities. Hopper crystals may he grown from supersaturatedsolutions of sodium chloride and from several of $he isomorphoussubstances. Here the growth is confined entirely to the edge, andseems to support the supposition that in a normal crystal depositionalways starts a t the corner or edge, the layer continuing,right acrossthe face.* There may therefore be two factors d-etermining thedifferences in the rate of growth perpendicular to the various faces :(i) the probability of the layer beginning a t the edge or corner of aface, and (ii) the rate a t which the layer can complete itself.A crystal bounded by plane faces in general has itsfaces rounded by dissolution, and other crystal forms are developedon it.A rock-salt cube dissolving in an aqueous solution of urea firstdevelops faces approximately of (25, 1, 0 ) and then the icositetra-hedron (25, 1, 1) which is unchanged in shape on further solution.57Etch pits and figures of various kinds are the usual phenomenaaccompanying the first stage of solution. A great deal of work hasbeen done on the " geometrical " aspect of solution. Spheres ofvarious substances have been dissolved in various agents, and thefinal shape taken up by the body (which does not alter on furtheraction of the agent) has been examined.58The factors which affect solution phenomena are : ( a ) temperature,as it affects the degree of under-saturation, ( b ) impurities in thesolution, (c) specific characters of certain crystal directions.( a ) Temperature as it affects the degree of under-saturation.The rate of solution, measured in mg.per unit area, has been foundto be approximately proportional to the degree of under-saturation(difference between momentary concentration a t the crystal faceand the saturation value).43 There seems to be but little differencebetween growth and solution velocities for the same degree ofunder- and super-saturation. With a small degree of under-satur-ation, the final end-shapes are bounded by relatively sharp edges,whereas with a large under-saturation it is usually much moreirregular .s7Solution.67 W.Schnorr, 2. KTist., 1915, 54, 309.5 8 For summary of this work, see Jahrb. Min., Bei1.-Bd., 1929, 60,* For theoretical confirmation of this see Refs. (48), (49), and (60).111CRYSTALLOGRAPHY. 279( b ) Impurities in the solution. Remarkable changes in the habitare brought about by solution in the presence of impurity. Recentwork of G. Friedel 59 and L. :Royer 60 is still more surprising. Theyfound that calcite gives etch-figures symmetrical about (011) in aninactive, but unsymmetrical in an active, solvent. Dolomite givesetch-figures on (100) and (TOO) enantiomorphous with respect to(011) in an inactive solvent, but, in an active, quite dissimilarfigures. Calamine etched by an inactive solvent gives pits sym-metrical with respect to a plane parallel to (loo), but an activesolvent indicates that a diad axis parallel to c is the only symmetrypresent.Further, if a d-acid is etched by a Z-alcohol, the etch figuresare enantiomorphous with those of a Z-acid etched by a d-alcohol.They are quite different from those obtained by etching a d-acidwith a d-alcohol. So far, these results have not been substantiatedby other workers, and in one case 61 contradictory evidence wasobtained. Etch figures are of so much importance in crystalstructure work that it is desirable that this phenomenon should beplaced on a sure footing.An enormousamount of data has been collected about this subject, and by workingwith single crystals of metal methods have been devised to eliminatethe effect of shape, impurities, and strain in the crystal.Thesolution figures and “ end-shapes ” which have been obtained arevery elegant, but quite inexplicable in terms both of structure andof the character and behaviour of the molecules in solution.The difference between crystal growth in a vapourand in a liquid, be it a melt or solution, is that the molecules or atomsin a vapour are usually unco-ordinated as they come near a crystal,whereas the immediate liquid environment of a crystal is almostcertainly a well-ordered one. A problem still to be investigated isthat of the “pre-crystal” existing in the liquid, and the factorswhich influence it.In the researches outlined above, no attempthas been made to explain why crystals have the directive forceswhich play such an important part in their growth. It is, however,clear that in a general kind of way, there are certain types of habitwhich are associated with a corresponding structure ; but it is almostimpossible to draw any certain conclusions from the mass of inform-ation that has been collected on the growth and solution of crystals,because very few of the aspects have been investigated from all sides,and insufficient systematic work has been carried out.(c) Specific characters of certain crystal directions.ConcZusion.69 Compt. rend., 1927, 184, 780.6o Bull. Xoc. frang. Min., 1930,53, 350; Compt. rend., 1929,188, 1176, 1303;61 T.M. Lowry and M. A. Vernon, 2. Krist., 1929, 70, 384.189, 932 ; 1930,190, 503280 BERNAL AND WOOSTER :Liquid Crystals.Half a volume of the Zeitschrift fur Kristallographie (1931, 79,Hefte l/4) has been devoted to the problem of liquid crystals. Itwas the editor’s aim to promote the study of the subject by enablingthe workers to arrive a t an accepted terminology, and to settle con-troversies by discussion. The first part of the volume containscontributions by the investigators who are interested in the subject,largely original, but also containing useful reports on other people’swork. This is followed by criticisms of one another’s work, whichgive a useful summary of current views. In a publication which ispresumably representative of European work, it is regrettable thatthere is not a single English contribution.Short summaries of thepapers are given below.The physical properties of the mesomorphous stases in general, andtheir importunce as a principle of clussi$cation (G. Friedel and E.Friedel). The word “ stasis ” is defined as applying to the differentstructural types of matter, e.g. , the crystalline stasis, or gaseousstasis, thus setting free the usual words “ state ” or “ form ” fortheir more ordinary meanings. “ Mesomorphous ” is coined todescribe the liquid-crystalline stases. To avoid confusion indealing h t h those mesomorphous stases which may show a varietyof appearances under the microscope, the word “ structure ” isreserved for a particular molecular state, and the word “ texture ”for homogeneous states in which the structure is constant.Thus,the texture may vary while the structure stays constant. There arefour stases in which a substance may occur, but not more than four :the solid crystalline, the smectic, the nematic, and the amorphousliquid. Mesomorphous stases differ from crystalline ones in havingfewer vectorial properties. They are spontaneously anisotropic,and change reversibly from one stasis to another a t a definitetemperature which is determined by the pressure. The smecticstasis is characterised by being very viscous, whereas the nematicis mobile. The authors have studied in great detail the opticalcharacter of many of the substances showing these properties. Bothsmectic and nematic stases are uniaxial, and under certain conditionsthey show interference figures in convergent polarised light.Certaincholesterol derivatives are nematic and show enormous rotatorypower. The differences in the X-ray pattern shown by smectic andnematic stases are also dealt with.Chemistry of liquid crystals (D. Vorlander). All substanceswhich on melting pass into liquid crystals have long-shaped orflat molecules. There is no distinction, as far as the capacityfor forming liquid crystals i s concerned, between those moleculeCRYSTALLOGRAPHY. 281which are symmetrical in their chemical formula and those whichare not. Polymorphism is very well marked in some liquid crystals,e.g., in p’-phenylbenzal-p-aminocinnamic acid ethyl ester thereare five melting points and four liquid-crystalline states.Theseare clearly differentiated by their viscosity, optical properties,and latent heats. Non-pleochroic liquid crystals when arrangedparallel show a uniaxial optically positive character, whereascircularly pleochroic liquids are negative in such circumstances. Acomparison of the optical properties of a number of organic substancesis also given.Experimental and theoretiml basis of the swarm hypothesis in liquidcrystals (L. S. Ornstein). The “ swarm hypothesis ” postulatesthat a molecule, by its shape or other characters, is able to orientatethe molecules around it. The author endeavours on this basis toexplain the optical, magnetic, and electrical effects, and the effectof the walls of the containing vessel.The scattering of light byliquid crystals is treated theoretically, and the predictions are verifiedby experimental observation. A magnetic field produces verymarked and rather complicated effects on the opacity of liquidcrystals, and changes in the dielectric constant are also well marked.A magnetic field perpendicular to the walls produces a decrease inthe dielectric constant by an amount which diminishes as thetemperature of the transition to the amorphous liquid is neared.Parallel to the walls, however, it produces a very much smallerincrease in the dielectric constant. The explanation given is thatthe molecules are oriented parallel to the walls of the vessel, and byreason of their mutual action this orientation extends some distanceinto the liquid.The long molecules are assumed to be anisotropicboth magnetically and electrically. They tend to set parallel tothe magnetic field, and at right angles to the electric field. Thusthe magnetic field perpendicular to the walls of the vessel causesthe molecules to turn round and thus to lessen the dielectric constant.When parallel to the walls, however, the magnetic field serves tobring the molecules in the middle of the tube more nearly parallelto the ones near the walls, and so to increase the dielectric constant.The size of the largest molecular group in the liquid crystal comesout to be 3 x cm. on the theory set out here. The action of thewalls is brought out clearly in the following experiment.A silverplate attached to a thermo-couple is immersed in a liquid crystal.A magnetic field applied perpendicular to the plane of the plateproduces a heating effect when switched on, and a cooling effectwhen switched off. If it is applied parallel to the plane of the plate,no such effect is obtained. The fundamental basis of the swarmhypothesis is given according to classical thermodynamics282 BERNAL AND WOOSTER :The optics of mesophases (H. Zocher). A discussion is given ingeneral terms of the various optical phenomena of liquid crystals.Explanations of the colours observed are given on the basis of theknown structures of mesophases.X-Ray investigation of Ziquid crystals (K. Herrmann and A. H.Krummacher). The authors criticise certain conclusions of deBroglie and E.Friedel on the size of the liquid-crystal molecule.The molecule diffracts the X-rays into a diffuse ring, which breaksup in a magnetic field into two “ brushes,” which stretch from thecentre outwards, and are orientated so that the line joining them isperpendicular to the direction of the magnetic field. The photo-graph of phenetoleazoxybenzoic acid ally1 ester, obtained with theviscous and mobile phases orientated by the magnetic field, arevery similar, the former being the better orientated. Photographsof crystals which had solidified when under the action of a magneticfield show the same orientation though not quite so marked.Measurements of the brushes give mean values for the dimensionsof the molecule perpendicular to its length which are in agreementwith what we should expect from its known chemical formula andthe sizes of atoms.The author is concerned onlywith mobile liquid crystals, which from their dielectric charactersfall into two groups, vix., symmetrical and unsymmetrical molecules.As an example of these, we have anisaldazine,CH30*C6H,*CH:N*N:CH*c6H4*ocH3,and p e t hoxybenzalamino- a-methylcinnamic acid ethyl ester,C,H ,O*C ,H,*CH:NC,H,*CH:CMe*CO,E t .The substances havingsymmetrical molecules show a reduction in dielectric constant whenthe field is perpendicular to the plates of the condenser, and a smallincrease when parallel. The amount of these changes depends onthe temperature, magnetic field, and electric field between thecondenser plates.When the unsymmetrical molecules are actedon by a magnetic field parallel to the electric field, there is a smallincrease in the dielectric constant. These differences are attributedto the tendencies of the symmetrical and unsymmetrical moleculesto set themselves respectively parallel to and perpendicular to thecondenser plates. By making certain assumptions, the dipolemoment of the molecules may be calculated from the experimentaldata (p = 2.3 x 1O-l8). By assuming dipoles to be present, the sametheoretical treatment may be used as for paramagnetism. This hasbeen done by Born, who finds a value for p 50% higher than thatobserved. The changes of the dielectric constant with constantmagnetic field and different electric fields are found.By applying theLangevin formula to the experimental curves, a molecular momentDielectric constant (W. Kast)CRY STALLOGRL4PHY. 283106 times that actually observed is obtained. The conclusion isthat groups of dipoles must be present in the anisotropic melt.Magnetic susceptibility (W. Kast). Both with p-azoxyanisole(mobile) and p-azoxybenzoic acid (viscous) there is a decrease indiamagnetic susceptibility on passing from amorphous liquid toliquid crystal. The general conclusion from the change of con-ductivity, of dielectric constant, and of susceptibility with temper-ature is that the number of swarms decreases with the temperature.The number of molecules which go to make up one swarm is estimateda t about lo5.Thiscontains a mathematical development of a simplified case to showthe dependence of the properties of liquid crystals on the temperature.Of the symmetry groups of amorphous and mesomorphous phases(C.Hermann). MM. Friedel have postulated that (1) the nematicstasis has the centre of gravity of the molecule orientated a t random,but that the molecules have their axes more or less parallel; (2) inthe cholesteric stasis the directions of the molecular axes form aspiral; (3) in the smectic stasis the centres of gravity lie in parallelplanes in addition to all the axes being parallel. E. Alexander andK. Herrmann have assumed that (1) in the nematic stasisthemoleculesform straight lines, (2) in the smectic and cholesteric stases themolecular centres of gravity form plane nets.C. Hermann proceedsto determine the total number of possible arrangements of the mole-cular axes, centre of gravity, etc., after making some assumptionsabout the equivalence of the molecules and the finite size of theconstituent atoms. This purely geometrical analysis is quiteexhaustive, and the author of it has shown exactly what character-istics the X-ray pattern of the various geometrical arrangementsshould have. The three or four types mentioned above are shownto be particular cases of the twenty possibilities.This is ageneral account of the nature and properties of all kinds of meso-morphous states. All forms of molecular aggregation-particularlybundles and plates of molecules-are considered, and a series ofobjections is raised to the swarm theory.A full discussion of thephenomenon of cloudiness and the ultramicroscopic and viscousproperties of liquid crystals is given, also the relationship of meso-morphous and colloidal systems.On the double refraction of thin layers of anisotropic liquids in amagnetic jield, and the orientating force within this layer (V.Frbedericksz and V. Zolina). When a liquid crystal is held betweena convex lens and a plane glass plate, with a magnetic field per-pendicular to the glass plate, and observed in polarised light, aProblems of the theory of anisotropic liquids (C. W. Oseen).On mesomorphous and colloidal systems (W. Ostwald)284 BERNAL AND WOOSTER :complicated phenomenon is seen. Up to a certain distance fromthe centre the field is dark, but beyond this there is a family of veryfine concentric bright and dark fringes.The critical boundarybetween the inner a,rid the outer field is independent of the cleannessof the glass walls; the critical thickness x and the magnetic field Hare related by the equation xH = constant = k, where k dependson the temperature. The theory given by Ornstein is able to explainthese phenomena. From this theory it may be deduced that themolecules lying on the glass itself do not move at all when themagnetic field is applied. Further, the authors find no evidence ofan inner dipole field and do not regard the swarm theory as beingessential for the explanation of their results.The discussion which follows is full of interest, but an account ofit cannot be given here.Though many controversial points areargued, there does not appear to be any marked agreement betweenthe various schools of thought.Optical Properties and Crystal Xtructure.Raman spectra of a great many crystals have been determinedsince the last Report on this subject in 1929. A summary and fullbibliography of the work up to 1930 have been given by S. Bhaga-vantam.62 The principal groups of crystals which have beenexamined are diamond,63 sulphur,64 inorganic chlorides, 65 calciteand aragonite,66 inorganic ~ulphates,6~, 68, carbonatesY68nitrates, 69, 70 chlorates, bromates, selenates, phosphates, 71 hydr-oxides, cyanides, and thiocyanates. 72 Certain groups of atoms arefound to have characteristic frequencies, and in this connexion theRaman spectra are extremely useful in supplementing the X-rayanalysis.Sulphur is a good example of it case in which the existenceof polymerisation may be detected by this method. The strongRaman line a t 1332 cm.-l in diamond corresponds to a frequency ingood agreement with that calculated from its known specific heatproperties. The examination of the chlorides leads to the conclusion62 Indian J . Physics, 1930, 5, 237; A., 1930, 1498.63 C. Ramaswamy, ibid., p. 97; S. Bhagavantam, ibid., pp. 169, 573; A.,64 P. Krishnamurti, ibid., p. 105; 1931, 6, 7 ; A., 997.65 Idem, ibid., 1930, 5, 113; A., 1930, 1344.6 6 S. Bhagavantam, 2. Krist., 1931, 77, 43; A., 668.6 7 P. Krishnamurti, Indian J. Physics, 1930, 5, 183; A,, 1930, 1344.68 N.Ernbirikos, 2. Physik, 1930, 65, 266; A., 1930, 1499.69 C. Ramaswamy, Indian J . Physics, 1930, 5, 193; A., 1930, 1344.?* P. Krishnamurti, ibid., 1930, 5, 1.'1 C. Schaefer, F. Matossi, and H. Aderhold, 2. Physik, 1930, 65, 289; A.,72 P. Krishnamurti, Indian J . Physics, 1930, 5, 633, 651 ; A., 146.1930, 1345; 1931, 145.1930, 1499CRYSTALLOGRAPHY. 285that covalent linkings in HgCl,, Hg,Cl,, ZnCl,, CdI,, SbCl,, BiCl,,and PCl, are necessary for the Raman effect to occur ; compoundspossessing only electrovalent linkings do not show Raman spectra,i.e., the chlorides of Li, NH,, Mg, Ba, Cu(ic), Ag, Cd, Sn(ous), andTh, and the iodides of K and Pb. The Raman spectra of the sul-phates show that the sulphate ion is easily deformable, beingaffected by the degree of hydration, size of the surrounding ions, andthe paramagnetism of the kation.The Raman line of the sulphateion is displaced much less from the exciting line in solution than inthe solid except in the case of MgS04,7H,0, where the converse istrue at certain concentrations of the solutions. I n the nitrates, theinactive frequency of the nitrate group appears as a sharp line, andon solution the greatest changes in its frequency are observed innitrates of the light and the heavy atoms. The results may besummarised by saying that the smaller the volume of the kation thegreater the frequency shift from its value in solution. The resultof the researches on the XY, group confirms the conclusion drawnfrom infra-red analysis, wix., that all the radicals form three-corneredmolecules with four inner frequencies, one of which is inactive.Inthe XY, groups, four frequencies only two of which are active arefound, again in confirmation of the work in the infra-red. Sodiumhydroxide shows a frequency shift (3630 cm.-l) considerably differentfrom that of water (3450 cm.-l), and is important in showing howthe Raman lines may be used to distinguish between water ofcrystallisation and of constitution. For the study of crystalstructure it seemed that the polarisation of Raman lines wouldprove most helpful, but up to the present the phenomenon is sur-rounded with difficulties both experimental and theoretical.73 Largecrystals appear to be necessary and different observers obtaindifferent results.That the Raman lines corresponding to the waterin gypsum vary markedly on changing the orientation of the crystalwith respect to the incident light and its plane of polarisation,suggests that this phenomenon may be very important as an aid tostructure analysis. The temperature variation of the Ramanspectrum of quartz and benzene has been studied by (Mlle.) M. J.Ney.'4 She finds that the Raman lines of benzene become broaderas the temperature rises, whilst those of quartz do not. Thisbroadening is attributed to molecules which rotate at the highertemperature. This would be an elegant method of showing in anyparticular case when rotating molecules were present.73 C. Schaefer, F. Matossi, and H.Aderhold, Physikal. Z., 1930, 31, 801 ;A., 1930,134$; 2. Physik, 1930, 65,319; J. Cabannes and (Mlle.) D. Osborne,Cornpt. rend., 1931, 193, 156.l4 Bull. Acad. Polonaiae, 1931, [A], 106; A., 1211; 2. Physik, 1931, 68,684; A., 665286 BERNAL AND WOOSTER :The relation between double refraction and crystal structure hasbeen treated by the Reporter 75 in an empirical way. Structuresmay be divided into the following types, which are characterised bycertain degrees of double refraction : (1) layer lattices-strongnegative double refraction except when the substance containshydroxyl ions ; (2) chain lattices-strong positive double refractionwhen the chain is parallel to the optic axis; (3) structures withstrongly asymmetric groups-double refraction large, the electricvector of the ray having the higher index being parallel to theshortest bonds ; (4) lattices with only symmetrical groups-lowdouble refraction ; ( 5 ) lattices consisting of a three-dimensionalnetwork-low double refraction ; (6) certain iron- and titanium-bearing substances-high double refraction which is not due tomarked asymmetry in the crystal lattice.Structures of organic compounds are generally too complicatedto permit of any similar generalisations, but in simple cases of long-chain or ring compounds this is not so.Thus, K. Banerjee 76 sawthe probable orientation of the naphthalene and the anthracenemolecule in their respective crystals from the optical and magneticproperties, and verified his expectations by means of X-ray analysis.CRYSTAL CHEMISTRY.V.M. Goldschmidt 77 has recently given another illuminatingaccount of the present state of the subject. The multiplication ofX-ray crystal analyses, with their greater accuracy and trustworthi-ness, and the development of quantum mechanical theory havebrought further confirmation of the essential rightness and fruitful-ness of his original assumptions on ionic size and co-ordination. Onthe theoretical side, the most important work has been the explan-ation of the physical nature of the effective forces holding crystalstogether. The fundamental ideas of ionic (electrostatic) cohesionand electron-sharing (valency) bonds have been considered in fargreater detail and the relations between them and the less well-known (the molecular and metallic) forces are beginning to appear.The HomopoZar Bond.-For the homopolar bond the most import-ant recent work from the point of view of crystal chemistry is thatof J.C. Slater and L. Pauling. The former 78 has calculated inter-molecular distances in molecules and crystals on the assumptionthat for electron exchange bonds both atoms will be a t such a76 W. A. Wooster, 2. Krist., 1931, 80, 495.7 6 Ind. J . Sci., 1929, 4, 557.7 7 Fortschr. Min., 1931, 15, 74.'* Physical Rev., 1930, [ii], 35, 509 ; 36, 57 ; 1931, [iiJ, 37, 481 ; A., 1930,1234CRYSTALTiOGRAPHY. 287distance that their maxima &J (electric density) coincide, while inthe case of ionic compounds repulsive forces prevent ions approach-ing closer than to a point where their density is about 10% of themaximum, In the second paper he suggested that exchange andionic phenomena both take part in very different degrees in differentmetals, and thus arrived at a reasonable value for the interatomicdistance of sodium.Pauling 79 has developed the case of homopolar binding in muchgreater detail.The theory cannot be discussed here, but some ofits most important contributions to crystal structure may bementioned. By means of it, he is able to predict the direction andstrengths of bonds formed between atoms sharing s, p y or d electrons.He concludes that “ p electrons will form stronger bonds than selectrons,” and that “ the bonds formed by p electrons in an atomtend to be oriented at right angles to one another.” This accountsfor the electric moment of water and ammonia, and also for thecurious square As, group in CUAS,.I n certain cases the 0-H bondmay be electronic. “ An atom, in which only s and p eigenfunctionscontribute to bond formation and in which the quantisation in polarco-ordinates is broken, can form one, two, three, or four equivalentbonds, which are directed toward the corners of a regular tetra-hedron.” This accounts for the tetrahedral carbon atom with freerotation about single, but not about double, bonds, and the tetra-hedral AX, groups, and also explains the pyramidal SO,, ClO,, etc.,configurations (see Slater),S0 and the kinked NO,’ ion. In specialcases, 3 s bonds may make larger angles, as in NO,,CO,, and graphite.With d electrons more variations are possible, “with a single deigenfunction no more than four strong bonds can be formed, andthese lie in a plane” as in the PtCl,” ion, “but if three d eigen-functions are available, stronger bonds directed toward tetrahedroncorners can be formed,” as CrOa”, while “ if two d eigenfunctions areavailable, six equivalent eigenfunctions can be formed.These formstrong bonds, of strength 2.923, directed toward the corners of aregular octahedron ” as in PtC1,” or towards those of a hexagonalprism as in MoS,. Besides the prediction of bond directions andstrengths, magnetic moments can be predicted or used as acriterion for the nature of bonds in complex structure.Ionic and Atomic Radii.--The two types of bond, homopolar andionic, have been shown by quantum mechanics to pass continuouslyinto each other.For purposes of crystal analysis the distinctionbetween bond types, in limiting cases such as the silver halides, isJ . Arner. Chem. Xoc., 1931, 53, 1367; A., 670; Physical Rev., 1931, 37,11 85.E o See J. C. Slater, ibid., 38, 325288 BERNAL AND WOOSTER :not a practical necessity. For the prediction of interatomic dis-tances and co-ordination, the concept of ionic radius and co-ordin-ation is quite satisfactory in the great majority of cases, even whereit is known that other forces are involved. The utility of this con-ception is only doubted outside the ranks of crystal structure workersby those who do not appreciate how far it has developed from theconception of a rigid hard ion to one whose size depends in a calcul-able way on the forces acting on it.Further, ionic sizes can besubstantiated quite apart from crystallography by pure quantummechanical calculation of electron distribution in atoms, and fromcalculations of lattice energy.W. H. Zachariasen 81 has prepared a new table of empirical radiiof ions of the inert-gas type. To apply these to ordinary crystalsthey must be corrected for co-ordination number, Coulomb force,and radius ratio. They are given as radii of corresponding univalentions for the co-ordination number 6. Zachariasen bases his workon the fundamental Born equationQ> = Ax,z2e2/R + B/R”@ is the lattice energy, x1 and x2 the charges on the ions, R the distancebetween them, A is the Madelung constant depending on the crystalstructure, B the Born repulsion constant, and the index n has values5,7, 9, 10, 12 for ions of the He, Ne, A, Kr, and X type respectively.From this he is able to find that approximatelyR12/R8 = R,/R, = R,/R, = R,/R, = ”-U1*391,R12/R9 = R8/R6 = R,/R, = ”-U1*296.(The subscripts here refer to co-ordination numbers.)The correction for valency is carried out by the approximate equationRZlt, = Rll/*-UzX where R , , is the actual interionic distancebetween ions of charge xl, z2, and R,, the standard univalent ionicradius.No correction for radius ratio is attempted; this is negligibleexcept when anions are in contact as in lithium chloride, sodiumsulphide, etc., where it leads to increase of interionic distance.Butthe estimate of the amount depends on a complete knowledge ofthe crystal energy.The table of ionic radii thus obtained is semi-empirical in so faras it bases itself on the values 1.33 and 1.81 A. for K’ and Cl’, butin 60 out of 81 cases it predicts an interatomic distance to within0.02 A. of the observed, and the nine cases when the difference isgreater than 0.05 all contain large ions of Br’, 1’, S”, Se”, and N”’,which are certainly in contact.2. K?%8t., 1931, 86, 137CRY STALLOORAPHY. 289To extend the theory of rare-gas type ions to those of the transitionmetals is much more difficult, because here the apparent ionic radiusvaries much more with the type of compound. Goldschmidt 82has made a beginning in the case of the first row of B group metalsCu+ (7.69), Zn++ (17~89)~ Ga3f (30~58)~ Ge4+ (45.50), As5+ (62*4),See+ ( 8 1 ~ 4 ) ~ comparing them to the corresponding Na+ (5*12),Mg++ (14~97)~ M3+ (28~32)~ Si4+ (44~95)~ P5+ (64.74), S6f (87.67). Thefigures in the brackets represent the ionisation potentials in volts;it will be seen that, whilst CuI>NaI, SeVI<SVI, whereas Si" ==: &Iv.According to Goldschmidt, other things being equal, a greaterionisation potential will lead to a decrease in interatomic distance,particularly with polarisable anions (presumably due to greaterexchange probability).Thus while the apparent radius of thetransition-metal ions in fluorides is, in general, greater than that ofthe corresponding inert-gas ion, yet in sulphides, bromides, andhydroxides, etc., they will be larger for arsenic and seleljiuIL1, equalfor germanium, and smaller for gallium, zinc, and copper.Thepractical equivalence of gallium and aluminium, germanium andsilicon, is shown to have wide geochemical importance.The case of the atomic radii of metals is even more complex.W. Hume-Rothery 83 has put forward an interesting semi-empiricalrelation d = n(l/uZ)% between d, the interatomic distance of ametallic element, and n the quantum number of the last closed shell ;2 is the atomic number, a is a constant depending on the valency,and x is approximately $. This equation gives a surprisingly goodagreement with observation. Other relations between ionic andatomic diameters have been suggested by E.Herlinger.g4The work of Niggli and his school 85 (see Ann. Reports, 1930, 27,289) lies outside the main course of crystal chemistry. Avoidingthe hypothesis of atomic size, they concentrate on the inter-atomic distances and the space pattern formed by the atomiccentres. I n this sense, it is a logical development of Weissenberg'stheories, but, owing to its geometrical rather than physical pointof view, it has not so far found much application in practice. Itsundoubted value is diminished by an extremely elaborate andprolix presentation.Apart from the development of existing theories, the past twoyears have seen the emergence of the ideas of molecular rotation andNorsk Qeol. T'idaskr., 1931, 12, 247.e3 Phil.Mag., 1930, [vii], 10, 217; A., 1930, 1233.84 2. Krist., 1931, 80, 465.s5 P. Niggli, ibid., 1930, 74, 375, 502; 75, 228; 1931, 76, 235; 77, 140;P. Niggli and F. Laves, ibid., 1930, 73, 381; 1931, 78, 208; P. Niggliand E. Brandenberger, ibid., 79, 379; F. Laves, ibid., 1930, 73, 202; 76, 277;T. Ito, ibid., 1930, 73, 357.REP.-VOL. XXVIII. 290 BERNAL AND WOOSTER :the hydrogen bond, which have thrown much light on obscure andcontroversial questions of crystal structure.Molecular Rotation in Crystals.-An anomaly in the entropy ofsolid hydrogen, led Pauling 86 to consider the possibility of movementof molecules in crystals. A molecule in a crystal is not fixed;considered as a rigid body, it can move about an equilibriumposition, and will do so with greater energy a t higher temperatures.But if the energy is such that the amplitude of these vibrationsapproaches x/2, there is the possibility of the molecule turning endfor end, and with further increase of energy the vibration may passinto rotation if the cohesion of the crystal is maintained.Wave mechanics do not give a sharp criterion between vibrationaland rotational motion.At every temperature there is always apossibility of the molecule turning end for end. Nevertheless, apractical criterion can be found separating the two states. If nis the quantum number of the vibration of the molecule, there willbe vibration or rotation according aswhere I is the moment of inertia and 2V0 is the total change ofpotential of the molecule passing from a position of stable to unstableequilibrium in the crystal.This expression can be approximatelyevaluated from specific-heat and band-spectrum data, giving thefollowing values of no + 1 and Vo :I,. N,. 0,. CO. CH,. HCI. HBr. HI. H,.no + 1 ...... . ........... 350 7.0 8.5 7.1 1.6 10.7 10.5 11.1 (0.4Vo, cels./mol. ......... 25000 450 600 600 90 1700 1300 1200 (56T (Abs.) transition 35.4O 43.8' 20.4' 98' 117' 126'The value of no + 1 for hydrogen shows that even a t absolute zerothe molecules are rotating, while for iodine rotation will not takeplace in the solid at all, as n = 12-15 a t the melting point. I n theother cases the transition takes place at a definite temperature ortemperatures below the melting point.These transitions have longbeen observed as maxima in the specific-heat curve and are nowexplained for the first time. (For further theoretical treatment,see T. E. Stern.87)This brilliant theory has already received confirmation in manyfields. From the equation we may expect rotation when the momentof momentum I of the molecule or the potential V of the directingforces is small. This will occur, not only for molecules, but forions and radicals movable about bonds permitting free rotation.Pauling had already predicted that in the structure occurring in86 PhysicaZ Rev., 1930, [ii], 36, 430; A., 1930, 1357.Proc. Roy. SOC., 1931, [A], 130, 551CRYSTALLOQRBPHY. 291the high-temperature form of the ammonium sa1ts;with transitiontemperatures for : NH41 (- 42-5"), NH4Br (- 38.0"), NH,C1(- 30-4'), the NH; ions are rotating and to be considered as spheresrather than tetrahedra.Similar examples have since been foundfor more complex ions. Ammonium nitrate, for instance, has beenfound by F. C. Kracek, S. B. Hendricks, and E. Posnjak 259 to havefive forms : a rhombic form, T<- 50°, with both NH,' and NO,'fixed ; another T<32", with NH,' rotating and NO,' fixed ; a mono-clinic form, T<125"; a tetragonal with NO,' rotating aboutthe normal to the plane of the ions; and finally the high-temper-ature cubic form, T> 125", isomorphous with sodium chloride whereboth NH,' and NO,' are rotating freely. Similar effects have beenobserved in sodium nitrate 260 and sodium ~ u l p h a t e .~ ~ ~ In general,the more symmetrical high-temperature polymorphs of inorganicsalts such as sodium sulphate and potassium chlorate 2679 268 probablyare due to complete or partial rotations.The diflticulty of placing hydrogen atoms in hydrated or co-ordination compounds is largely removed by this conception.Ammonia and water are, for instance, often found on triad or tetradaxes of symmetry too high for their intrinsic symmetry, e.g., inCo(NH,),Cl, and alum. In all these cases the true symmetry of theradicals is infinite owing to rotation. Rotation will always takeplace about single bonds unless hindered by stereochemical con-siderations. Similarly, in the high-temperature form of tridymiteand cristobalite, the oxygen atoms probably do not lie anomalouslyin the straight line between two silicon atoms, but rotate about it ata small distance. One of the most interesting applications of theidea of rotation is in the settling of the controversy on the form ofaliphatic chains (see Report for 1928).Examination of paraffinsand fatty acids pointed to a zigzag chain of carbon acids, while inthat of long-chain amine halides the carbon atoms lay on tetradaxes and seemed necessarily collinear. This is now shown to be dueto rotation about an axis parallel to the chain length. S. B. Hend-ricks489 has shown, by repeating his experiment at liquid-airtemperatures, that a larger cell appears, pointing to a zigzag chainat rest. On the other side, A. Miiller 470 has shown, by heatingparaffin crystals to within a few degrees of the apparent meltingpoint, that while the cell remains unchanged, the disappearance ofcertain X-ray reflexions points to rotation of the molecules abouttheir long axes (see p.305).The Hydrogen Bond.-The position of hydrogen atoms has alwaysbeen a great difficulty in crystal structure. They are too light toaffect the intensities of X-ray reflexion, yet they obviously occupyspace and play a considerable part in the dynamics of the structure292 BERNAL AND WOOSTER :The rotation of molecules and radicals furnishes one explanationof the failure to fit them into crystal structure. More importantis the conception of the hydrogen bond postulated by Huggins,appearing more and more frequently to explain X-ray crystalanalyses and finally given a theoretical explanation by Pauling.79The bond is not covalent but ionic. With atoms of large electronaffinity (fluorine, oxygen, and possibly nitrogen) the hydrogen atommay lose its electron and become a small positive ion which, there-fore, has the co-ordination number two, and can thus form thegroup [F’H’F‘]’ or [O”HO“]”’. Such groups have long beenrecognised in crystals : the former occurs in all acid fluorides. Forthe latter, two cases occur. If, as in magnesium hydroxide, the sumof bond strengths (see Report for 1929) reaching the oxygen atom is 1,we may safely assume an (OH) group, with the proton inside theoxygen atom. If, however, as in potassium dihydrogen phosphate,282staurolite, Fe(OH),,Al,Si,O,,, a p ~ p h y l l i t e , ~ ~ ~ H,KCa4Si,0,,(OH)8F7and lepidocrocite, FeO(OH), the sum of bond strength is 8, occurringtwice for each hydrogen, we must expect a [O”’”’]”‘ group.Thiswill occur most easily when the oxygen atoms are attached to highlycharged small positive ions. We may say, therefore, that inanhydrous acids and acid salts, hydrogen behaves like a positive ion ;otherwise it is attached by a covalent link to oxygen and appears ashydroxyl ion. (In acid hydrates the hydrogen bond may be brokenby the formation of oxonium ions, OH,’.) Apart from structuralevidence, the hydrogen bond is also suggested by Raman spectra.88It is impossible to give any account of the crystal structuresanalysed in the past two years. Instead, a fairly complete list isappended giving both new crystal types established and substancesbelonging to well-recognised crystal types.What follows is in thenature of a commentary on this list, stressing the chemical andsystematic rather than the geometrical and crystallographic aspects.For this reason, few axial lengths are given and only the shape andsymmetry of ions and molecules are considered.Metallic CrystaZs.-The classification of metallic and semi-metallic structure has progressed much in the last years and is nowfairly complete except for our lack of knowledge of the compoundsof the alkali and alkaline-earth 89 These being omitted,metallic and semi-metallic substances so far studied can be classifiedinto four main groups : TT’, TM, TD, MM’, where T stands for atransition element including copper, silver, and gold ; M for a metal88 C .Kasper, J . Amer. Chem. SOC., 1931, 58, 2424; A., 893.e0 U. Dehlinger, Ergebnisse der Exakten Natumissenechctfte, 1931, 10, 325 ;J. D. Bemal, Ergebnbse der Technischen R6ntgekunde7 1931,2, 200; Metccll-wirt, 1930, 983; M. Neuburger, 2. Krist. ,1931, 80, 103; A., 1217CRYSTALLOGRAPHY. 293or semi-metal of the other B sub-groups including (Mg), Al, Si, P,and S, but excluding the halogens, and D is one of the first-rowelements, H, B, C, N.TT’ is represented by the transition metals themselves, theirextensive solid solutions with each other and their compounds. Thegreat majority of these are face-centred, body-centred, or hexagonalclose-packed in structure, and only differ from solid solutions by thearrangements of the atoms of their components regularly with respectto each other, thus acquiring electrical and mechanical propertiesmore like those of pure metals than alloys.This has been particu-larly well studied in the case of AuCu and AuCu, by U. Dehlinger 126and K. Oshima and G. Sachs,lZ5 and for AgPt and AgPt, by C. H.Johannson and J. 0. Linde.12’The allotropy of metallic elements has been much studied byX-rays.89 The transformations of thallium, cobalt, and manganesehave been fully confirmed, and new allotropic phases have beenfound for chromium, tungsten, nickel, and rhodium. In all thesecases, however, it is not quite clear that the possibility of sub-hydrides has been excluded, which might account for the com-plicated structures observed.The TD or interstitial compounds of the transition metals withhydrogen, boron, carbon, or nitrogen, practically unknown threeyears ago, have now been so thoroughly studied, principally byG.Hagg,l40* 143 that it is possible to form a general picture of theirconstitution. Nearly all fall into six groups 12a,4, 12b,4, 8a,4,12a,6, 12b,6, 8b,6, in Hagg’s notation, in which the metal atomsare respectively cubic face-centred (12a), body-centred @a), hexa-gonal close-packed (12b), or simple hexagonal (8b) lattices with thenon-metallic atoms (or in some cases atom pairs C2,H2) in theinterstices between 4 or 6 metal atoms. The metallic lattice thusformed differs little from that of the pure metal with a slightlylarger lattice parameter and greater cohesion, and often with a slightdistortion to lower symmetry.The kind of structure seems todepend primarily upon the relative size of the inserted atoms.Where this is too large, as in Fe,B, FeB, FeSi, Fe,P, more compli-cated structures result. S. B. Hendricks and P. B. Kosting162have determined the structure of several of these compounds. Inall of them, the co-ordination of metal atoms about the non-metalis preserved. Of particular interest are the compounds of the iron-carbon system. The structure of the unstable tetragonal marten-site has been studied in detail by E. Ohman,ld4 and its formationfrom austenite (y-iron) and breakdown into ferrite (a-iron) andcementite (Fe,C) have been studied on single crystal specimensby G.Kurdjumov and G. Sach~.l*294 BERNAL AND WOOSTER :The details of the cementite structiire have been determined byS. B. Hendricks and by S. Shim~ra.l4~ They differ only in theposition of the carbon atoms. According to the more probablestructure of Hendricks, the carbon atoms lie between distortedoctahedra of iron atoms which themselves occupy positions inter-mediate between face-centred and body-centred co-ordinations.For TM compounds, recent work has extended and confirmedHume-Rothery’s rules (Ann. Reports, 1929,26,289). The characterand crystal structure of the compound are determined by the ratioof electrons to atoms, counting electrons from the last completedshell of Ne( lo), Ni(28), Pd(46) (the eighth-group metals themselvescounting as zero).As the ratios get larger, the character of thecompound becomes less and less metallic : Ratio 3 : 2, body-centredcubic or p-Mn structure; 21 : 13, y-structure; 7 : 4, close-packedhexagonal; 5 : 2, NiAs structure; 4 : 1, FeS, structures (pyriteand marcasite). This illustrates quantitatively the natural expect-ation that the greater the proportion of the metalloidal elementor the higher its group the greater the departure from metalliccharacter of the resulting compound.The most curious of these ratios and structures (that of the 21 : 13,y-structures) has been extended to the compounds of the eighthgroup. A. Westgren and W. Ekman 1659 166 have prepared alloysX5ZnZ1, where X = Fe, Co, Ni, Rh, Pd, Pt, and Ni,Cd,,, all with oneor other of the varieties of y-structure.A. J. Bradley and C. H.Gregory,lss on the other hand, have made an exhaustive studyby means of X-ray intensities of Cu,Cd, and Cu5Zn8, and havefound that, although the atomic positions are essentially the samein these structures, the different kinds of atom are not similarlydistributed in the two cases studied. Electron number seems todictate the structure chosen ; individual atomic positions aredetermined quasi-statistically by considerations such as atomic size.The compounds of the heavy B-group metals, Hg, T1, Pb, Bi, arein general different from those of the elements in correspondinggroups: CuHg, for instance, forms a y-structure but with theproportion of electrons 19 : 13 instead of 21 : 13.Nothing new has been found about the structures of the B-groupmetals, but an important generalisation has been pointed out byHume-R~thery.~~ Except for the heavier elements, all B-groupelements have structures in which each atom has ( 8 - N ) nearestneighbours where N is the group number of the element.Thus,in BrVII each atom has one neighbour, in SeIV 2, in AsV 3, in Gem 4,in GaIII 5, and finally in ZnII 6. This is clearly a consequence of thepartially homopolar nature of the binding in these cases.SO W. Hume-Rothery, Phil. Mag., 1930, [vii], 9, 65; A . , 1930, 279CRYSTALLOGRAPHY. 295Several MM’ systems have been studied, but except for simplerock-salt structures such as SnSb, none of their structures has beenworked out.More, however, has been done on sulphides. Themarcasite structure has been found by M. J. BuergerZo6 to beessentially similar to pyrites, formed of S, groups co-ordinatedwith 6Fe. Argentite, acanthite, chalcocite (Ag,S and Cu,S) ,04have been shown to be closely related, but the complete structureshave not been worked out. J. W. Gruner203 has written a verycomplete account of present knowledge of the structure of sulphidesand sulpho-salt s.As in previous years, more of crystal structure work has beendone on ionic compounds than on all other substance types puttogether. Nearly all the structures found, however, agree withthe picture of structure as elaborated by Bragg, Goldschmidt, andPauling, and in a great number of cases the structures themselvesmay be predicted by Pauling’s rules (see Ann.Reports, 1929, 26,295) and need only have the atomic positions checked by X-rayanalysis. As before, we will divide them somewhat arbitrarily intofive sections: (1) simple ionic oxides and halides, (2) salts withpolyatomic ions, (3) hydrated salts and co-ordination compounds,(4) complex oxides, hydroxides, basic and mixed salts, ( 5 ) silicates.(1) Xirnple Halides and Oxides.-E. Zintl and A. Harder 208 haveanalysed the structures of all the alkali hydrides. These, unlikethe transition-metal hydrides (see p. 293), are plainly ionic incharacter and have a sodium chloride structure. The latticedimensions a (in 8.) are : LiH, 4.084; NaH, 4.880; KH, 5.700;RbH, 6.037; CsH, 6-376.The radius of the hydrogen ion H’is 1.36-164 A., thus lying between fluorine (1.31) and chlorine(1.81), though nearer the former, so that mixed crystals can beformed between LiH and LiF. The alkali cyanides studied byG. Natta and L. Passerini 209 are also isomorphous with the halides :the radius of CN‘ may be taken as 1.92, lying midway betweenthat of C1’ (1.81) and that of Br’ (2.00). Thus we have the sequenceof univalent negative ions : F, H, C1, CN, Br, I.Apart from this, the chief advance here has been the elucidationby P. Ebert, H. Brakken, and N. Wooster of the structure of AX,compounds, particularly difficult on account of their hygroscopicproperties. Most of the halide structures lately studied are foundto be based on a close packing of halogen ions and thus resembleeach other in lattice dimensions and general character.Thus,referring them to hexagonal axes, we have :LiC1. MgC1,. CrCl,. FeCl,.a ........................ 6-28 6-20 6-02 5.92c ........ . ............... 17.8 17.3 17.3 17.296 BERNAL. AND WOOSTER :In all these cases the metal ions lie between six C1’ ions, the differencebeing that in the first case the C1’ ions are similarly surrounded bysix Li’ ions, while in others, owing to the higher polarising power ofthe kations, the C1’ ions have three or two kation neighbours onone side only, giving rise to layer lattices. Where the valenciesof the kations are different, mixed crystal formation can even takeplace, as between LiBr and MgBr,.The fluorides have structures different from those of the otherhalides but they are also based on close packing.In the halidesof the heavy metals, lead chloride and mercuric bromide, F. D.Miles,221 M. Mathieu,222 and H. J. Verweel and J. M. Bijvoet 223have shown that there is a tendency to form definite molecules,so that these are strictly only semi-ionic compounds. The tetra-halides are also molecular (see p. 303).Among oxides, the structure of the C group of the sesquioxides,of which bixybite is the type, is particularly interesting, as it isthe first case where two alternative structures are absolutely in-distinguishable by X-ray methods. The structure consists of(FeMi)” ions in a slightly distorted cubic close packing, each sur-rounded by a much more distorted 0” octahedron.The metalatoms are fixed by a parameter, a change of sign of which does notaffect the X-ray intensity. L. Pauling and M. D. Shappel1235find that the negative value gives reasonable interionic distances,whereas the positive value originally chosen by W. Zachariasen 236does not. Chromic, molybdic, and tungstic anhydrides, studied byH. Briikken 242 and W. A. Wooster 340 and N. I V o o ~ t e r , ~ ~ ~ are notisomorphous. The second appears to be a larger lattice based 011molybdenum-oxygen octahedra sharing edges. The third, althoughtriclinic, approximates to a cubic structure of side 3.75 A., withthe tungsten atoms a t the corners and the oxygen atoms halfwayalong the edges.(2) Anhydrous SaZts.-The chief interest in the Structure of saltswith complex ions lies in the light that can be thrown on the sizeand shape of the ions.These may now be classified as follows :linear ions, XX, XY, XYZ, BX,; straight or angular, planar ionsBX, ; tetrahedral or square ions BX, ; octahedral ions BX,. Of thefirst type the carbides or more properly the acetylides have beenshown by M. von Stackelberg214 to be ionic compounds of (CiC)”or (H*CiC)‘, forming tetragonal crystals and showing evidenceof belonging to a cubic (rotating 1 ) form a t higher temperatures.He has also shown245 that the hexaborides CaB,, SrB,, etc., havea CsCl structure of Ca and B,, the latter an octahedron of boronatoms. This is very difficult to understand in terms of either ionicor homopolar binding. The azides, NNN’, 246-248 have straighCRTSTALLOGRAPHY.297N Cl ions, but the nitrites, 0 0, and chlorites, 0 0, have been definitelyshown by G. E. Ziegler 251 and G. R. Levi and A. Scherillo 250 tohave angular ions according to the predictions of Zachariasen 252and Slater 8O (see Ann. Reports, 1929, 26, 301).Sodium sulphite and lithium iodate, which have been verycarefully studied by Zachariaseny2539 254 show pyramidal AX, groups ;the latter may even be considered as a mixed oxide, L i T and 0;’.The very interesting group of fluocarbonates studied by I. Ofteda1264have been shown to be based on a hexagonal net of [Ce,(La, Nd, etc.)of side 4-09 8. as in the trifluorite tysonite,226 CeF,. TheCO,” groups pack between these layers parallel to the trigonalaxes, thus giving rise to positive instead of the negative birefringenceof most other carbonates.The close similarity of the hexagonalnet of these compounds gives rise to parallel growths and continuousreplacement of F, by CO, in single crystals.Of AX, types, most interesting are the cubic, high-temperatureforms of the perchlorates of Nay Ag, NH,, K, Rb, Cs, and T1, studiedby K. Herrmann and W. Ilge267 and by H. Brakken and L.Harang,268 which are essentially of sodium chloride type. In thiscase also the high symmetry may be due to rotation or oscillationof the group C10,’.Potassium dihydrogen phosphate has been investigated by J.West 282 with an elegant application of the Fourier method avoidingall a priori assumptions of scattering power, extinction, etc.Inthis way an almost regular tetrahedron is found for the PO, group,of 2.46-2-6 A. side. The distribution of the tetrahedra withrespect to each other and to the potassium ions strongly suggestsa hydrogen bond between neighbouring PO, groups, so that theformula might be writtenH H0 0HOPOHOP0H.--0 0H K H0 0HOPOHOPOH _ _0 0H HI II IThe structure of apatite, the leading member of an importantgroup of mineral phosphates, has been fully worked out by S. vonNBray-Szab6 283 and RI. Mehme1,284 who agree in essentials. It isan excellent example of the influence of crystal structure on thevery existence of compounds. To form Ca,(PO,), crystals seemsIt298 BERNAL AND WOOSTERto iiivolve a geometrically difficult arrangement! of atoms, for it isnever formed in nature or artificially.Instead [CaS(PO,),]* bala,ncesits electric charge by the addition of one halogen atom which liesbetween three calcium atoms on triad axes, so that the formulamay be written (Ca,F)*Ca,(PO,),.(3) Hydrated Salts, etc.-As the result of recent work, the r d eof water of crystallisation is becoming clearer.g1 Where water isfound in a crystal, apart from hydroxyl groups decomposed onlyat high temperatures, it can occur in a variety of ways : (1) Asisolated molecules or chains of molecules in holes in a firm structure(zeolitic water); here it can be removed and replaced withoutdestruction of the crystal. (2) I n sheets separating anhydroussections of the crystal; the classical case is gypsum.(Here isan interesting case of isomorphism between gypsum, CaS0,,2H20,brushite, CaHP04,2H20, and ardealite, Ca,HP04S0,,4H20.)299(3) Co-ordinated as tetrahedra, octahedra, etc. , around definiteatoms in the structure K,[Mg(OH,),](SO,),. (4) Possibly in thecase of polyhydrates a continuous ice structure exists, in the holesof which the ions are placed,Two important examples of isomorphous series of hydrates havebeen analysed in the last two years. The structure of NiSnC1,,6H20,studied by Pauling, 304 is that of the large series of the general typeA11BIVX,,6H20 (or 6NH,), where A can be Mg, Mn, Zn, etc., B isSi, Sn, Pd, Pt, etc., and X is F, C1, Br, I . The structure is essentiallya body-centred cubic caesium chloride structure, with [A116H20]+2for Cs and [BX6]-2 for C1.The water or ammonia molecules andthe halogen atoms form almost regular octahedra round the metalatoms, but the larger size of the last lead to distortion to rhom-bohedral symmetry.W. Hofmann 306 has analysed Tutton’s monoclinic double sulphatesM12MIIX0,,6H,0, where MI is I<, NH,, T1, etc., MI1 is Mg, Zn, Cd,etc., and X is S, Se, etc. ; and by a method of comparing intensitiesof reflexion between (NH4),Mg(S0,),,6H20 and Tl2Mg(SO4),,6H,O,(NH,),Cd( S O4),,6H,O, and (NH,),Mg( Se04),, 6H,O, he has deter-mined the parameters of MI, MI1, and X. The position of theoxygen atoms and water molecules is less certain, but the best fitis obtained by placing the former in the usual tetrahedron round Xand the latter in an octahedron round MI1.(4) Complex Oxides, Hydroxides, etc.-The mixed oxides andhydroxides do not form a class of their own.They are connected91 L. Hackspill and A. P. Kieffer, Ann. Chim., 1930, [XI, 14, 227; A., 1930,1535; F. J. Garrick, PhiZ. Mug., 1930, [vii], 9, 131; A., 1930, 276; A. Seye-wetz and Brissaud, Compt. rend., 1930, 190, 1131; A., 1930, 872; W. H.Keesom and H. H. Mooy, Nature, 1930, 126, 243; A., 1930, 1233CRYSTALLOGRAPHY. 299by isomorphous relations t,o the simple oxides (Fe203, hematite ;E’eTiO,, ilmenite), to the complex-ion salts (Ag2Mo0, ; A12Mg04,spinel) and to the silicates (Mg2Si04, olivine ; A12Be04, chrysoberyl).Their distinguishing character is their heterogeneity and the absenceof highly charged small positive ions, so that no electrostatic valen-cies higher than 1 exist throughout the structure.They may be classified by means of the kation oxygen (hydroxy-fluorine) co-ordinations found in them.These co-ordinationsrange from 4 (only in spinels and allied structures) to 6, which isthe rule for most of the following kations : Sb5+, Nb5+, Tit5+, Ti4+,Sn4+, A13+, Sc3+, Ga3+, Cr3+, Fe3+, Mg2+, Mn2+, Fe 2+, Ni2+, Co2+,Cu2+,Zn2+,Li+ ; 6-8forZr4f7Hf4+, Ce4+,U4+, Th4+, (Sm3+. . . .cp3+),Y3+, Ca2+, Cd2+, Na+; and 8-12 for (La3+. . . . Sm3+), Sr2+, Ba2+,Pb2+, K+, Rb+, Cs+.The following seven types of structure have been observed :[A2]6[B]40, Spinel ; 1:A]6[B]603 Ilmenite ;[A2I6[Bl6O5 Pseudobrookite ; [A]6[B2]60s Columbite ;[A2]6-s[B,]60, Pyrochlorite ; [A2]8-12[B]603 Perovskite ;[A3]s[B2]6[C,]40,2 Garnet.A and B may be any of the metals of the above list, with therestrictions that the co-ordination rules be observed and that thepositive charge of the kations is exactly balanced.This can bedone by adjusting the charges between the A and the B atoms bysuch replacements as Nb5+, Fe2+, by Ti4+, Fe3+, or, where the totalcharge is deficient, by the replacement of oxygen by hydroxyl orfluorine, so that, for instance, the general formula for a pyrochloritemay be written[a4A4+ /a.,A3+ /a,A2+ /a,A+I6[b,B5+ /b4B4+ /b,B3fl6/xO /y( OH) / x Fwhere a,+ a3 + a2 + a, = 2; b, -/- b, + b, = 2 ; x 4- y + 2 = 7 ;and 4a4 + 3a, + 2a2 + a, -+ 5b5 + 4b4 + 3b3 = 2x + y + 2.The spinels are still providing most material for study.Manynew examples of this already large group have been found, includingsuch unexpected compounds as CUA~,O~, MgGa204, Ni,Ge04, andZn,Sn04. In last year’s Report on Geochemistry, critical remarkswere made on the indehite formulze given by X-ray workers tospinels. Unfortunately, this indefiniteness is due to Nature. Thespinel cell is a definite entity, a cube of side 8-1-83 A,, containing24 metal atoms and 32-36 oxygen atoms. Any spinel can, how-ever, always be considered a mixed crystal between true spinel,A2BX,, and y-A1203, or magnetic Fe,03. The structure of thelast has been determined by J. Thewlis328 from intensity measure300 BERNAL AND WOOSTER :ments. The four extra oxygen atoms are placed in positions pre-serving an Fe-0 distance of 1-9 A.; otherwise the structure is thatof spinel. The accepted spinel structure has been questioned byP. Machatschki 329 and T. 3'. W. Barth and E. Posnjak 330 in differentsenses. Machatschki, by changing the oxygen parameters from0.375 to 0.384 in MgAz,O,, and making the aluminium octahedratighter and the magnesium tetrahedra looser, gets both better agree-ment with intensities, and interatomic distances more in accordwith modern views. Barth and Posnjak, on the other hand, propose,from the study of MgGa,O, and MgPe,04, the more radical changeof half the Ga(Fe"') atoms to the tetrahedral positions, leavingthe remainder of the MgGa( Fe" Fe***) in statistical distributionover the octahedral positions, so that the spinel formula should bewritten as (MgAl)AlO,, and magnetite as (Pe" Fe"')Fe"'O4, whilstMg2Ti04 would remain as before. Both these suggestions may be true,but further work is needed.CaIn20, and CdIn,04 340 belong to therelated Mn304, hausmannite type. On account of its complexity,P-alumina has occupied the attention of X-ray crystallographersfor some years. W. L. Bragg, C. Gottfried, and J. West345 havefinally decided that it is really an acid aluminate, Na,AI,,O,,,. Itmay be considered a compound of corundum (aluminium 640-ordinated), y-Al,03 (aluminium 4-co-ordinated), and sodiumaluminate, arranged in layers.The titanates, pseudobrookite, Fe,Ti05, and columbite,(E'e,Mn)(Nb,Ti),06, have been analysed by L.Pauling 342 and J. H.Sturdivant 341 ; both titanium and niobium are found in 6-co-ordin-ation.H. R. von Gaertner,Ng F. Machafs~hki,,~~ and E. Branden-berger 357 have investigated complicated niobates and antimonates.Of these, loparite, (Na,Ca,ce),(Nb,Ti),O,, appears to belong to theperovskite type with a small cubic cell a = 3.84 8., whilst theothers, atopite, mauzelite, and koppite, belong to a new type,that of pyrochlorite, also cubic, a In this type, A2B207,A seems to be 6-8-co-ordinated (the oxygen positions are uncertain)and B 6-co-ordinated.Of complex hydroxides, hambergite, Be2B03(OH), is the onlyone that has been fully analysed. Zachariasen's work 344 is partic-ularly interesting in showing B**' always co-ordinated with 30.TheBO,"' triangles lie parallel to the c axis, giving rise to strong positivebirefringence.The oxides and hydroxides of aluminium and iron have beenmuch studied, but no new structures have been advanced. Thesystems are very complex : there are at least four forms ofA1,O8,3H,O distinguishable by X-rays.10 ACRYSTALLOGRAPHY. 301Some very complex ionic: compounds come most naturally intothis section. The boleite--pseudoboleite group,xPbCl,,z~AgCl,xCu( OH),,has given rise to controversy,348 but it seems that instead of beingcubic they form a related tetragonal group with multiple relationbetween the axes as in the bastnaesite group (see above).(5) Silicates.-The analysis of the silicate structures and the dis-covery of their natural classification have been the greatest triumphof X-ray crystallography.In the last two years the field has beennearly covered. The structures of all the common silicate types, aswell as those of many rarer ones, are now known. W. L. Bragg, whowith his school has accomplished most of the work, has given a fullaccount 360 of all silicate structures determined up till now in " TheStructures of Silicates '' (2nd edtn., 1932), so no description of newstructures will be attempted here. Machatschki's classificationof silicates has been extended and modified by V. M. Goldschmidtand S. Nhray-Zab6. It is based essentially on the mode of bindingof tetrahedra of (sio4)4' and also of (B04)5-, (Be0J6-,(Zn04)6-, etc. The simple silicates, those containing no other4-co-ordinsted ion, form a series of increasing acidity :(sio4)4-, separate tetrahedra (orthosilicates) ;(Si20,)6-, pairs of tetrahedra with one corner shared (disilicates) ;(Si309)6-, ring of tetrahedra [benitoite, BaTi(Si,Og)] ;(Si601s)12-, ring of tetrahedra (not yet found except in the beryl-(Sin 0,) 2n - , chain of tetrahedra (me tasilic a te s , pyroxenes) ;(Si4n011n)6n-, band (double chain) of tetrahedra (amphiboles) ;(SiZn05n)2n-, sheet of tetrahedra (mica, talc, chlorite group),SiO,, framework of tetrahedra (tridymite, quartz).This main sequence can be varied in two ways.losilicate, beryl) ;never found in simple silicates.With any simplesiIicate can be combined groups, chains, or sheets of oxides orhydroxides, thus Mg,SiO,, olivine, combined with Mg( OH), sheetsgives the norbergite, clinohumite series; rows of ALO, exist withAISiO, in cyanite, and Al,F, groups in topaz, A1,F2Si04.Thisgives rise to a whole series of basic silicates corresponding to eachsimple silicate and extending to cases such as talc, MgSi20,,2Mg(OH),,where the simple silicate MgSi,05 is not stable. On the otherhand, some of the Si4+ in a silicate can be replaced by AP+(B3+,Be2+),either in stoicheiometric or in indefhite amount, increasing thenet charge of the complex ion. Thus, diopside, CaMg(SiO,),,gives rise to augite, (Ca,Na)(Mg,E'e,Al)(A1,Si),O,, and tremoliteto hornblende. With more acid silicates, such as the mica an302 BERNAL AND WOOSTERfelspar group, only aluminosilicates are stable, the first beingcharacterised by sheets of tetrahedra with the ratios (Si,Al)205, thesecond by various spatial frameworks of formula (Si,Al)O,.I ngeneral, beryllo- and boro-silicates resemble aluminosilicates, butsome structures can be formed which would be impossible forsimple silicates such as phenakite, Be,SiO,. A silicate can, ofcourse, be basic, hydrous, and aluminous a t the same time, andthis is the cause of much of the apparent complexity of silicateformulE.Notable work of the past two years includes the structure of theorthosilicates sphene, CaTiSiO,, by W. H. Zachariasen ; 363 eulytite,Bi4(Si04)3, by G. Menzer; 362 and the establishing of Si,O, groupsin thortveitite, melitite,367 h a r d y s t ~ n i t e , ~ ~ ~ m e l i ~ h a n i t e , ~ ~ ~ andvesuvian,370 and of the (Si309)6- group in benitoite by Z a ~ h a r i a s e n .~ ~ ~The complete scheme of the monoclinic and orthorhombic pyroxenesand amphiboles has been worked out by B. E. Warren.376-380 Thesehave all been shown to be derivable from bhe simplest type, mono-clinic pyroxene (diopside). The rhombic pyroxenes are formed by areflexion of the cell in the (100) plane, the monoclinic amphibolesby a doubling of the b axes, and consequently of the silica chains.The rhombic amphiboles arise in turn by reflexion in the (100)plane, The wollastonite, CaSiO,, group is shown to have no re-lation to the pyroxenes and to be triclinic instead of monoclinicas had been previously supposed.376The study of the mica group has been carried out by Pauling 385and by W.W. Jackson and J. West.386 The great variety of platyminerals, micas, brittle micas, chlorites, and tales, have beenshown to be produced by various combinations of hexagonal layersof (Si4nOlo,)-4n, (Si,,AI,O (Si2nA12,0 10n)-6n, etc., withMg(OH),,Al(OH),,A10( OH), and neutralised by ions of K', Nit',Ca**, Mg**, etc. The structure of apophyllite 392 shows i t to be analternative net-like silicate based on square, instead of hexagonal,meshes.Thestructure of these is not exactly known, but that proposed by F.Schiebold 400 must be near the truth. The zeolites 411-40 have beenmuch studied, especially by Pauling. The frameworks on whichthese compounds are based seem chiefly of three types. Thosebased on squares and collapsed octagons (danburite, felspar type),those based on squares and hexagons (cuboctahedra) (ultramarine,sodalite type), and those based on hexagons alone (tridymite,nepheline type).More complex arrangements are found in thefibrous natrolite, scapolite, and helvine groups. X-Ray analysishas been used successfully in the study of synthetic silicates andDanburite 399 is a borosilicate closely related to the felsparsCRYSTALLOGRAPHY. 303even of glasses. It will probably become indispensable in thesefields. It has already proved that the synthetic amphibole formedin the magnesia-silica system is really olivine.42sV. M. Goldschmidt 338 has shown that germanium forms a wholeseries of compounds isomorphous with all the chief types of silicates(incluciing germanium-olivine, phenakite, and pyroxene), so thatin future the study of the silicates must include that of the germ-mates.Molecular Compounds.--Enough simple molecular compoundshave been analysed to show that fundamentally all have the samestructure, that of cubic close packing.435-450 An exception ispara-hydrogen, which is hexagonally close packed.The latticedimensions of all simple molecular elements and compounds so fardetermined are set out below (in A.U.), r being the “effectiveniolecular radius :F‘.1.33Br’.3.03-75~ = 6 . 1 21.88--H2.Ne. NH,. CH,. Cl’. A. HCl. H,S. H,P.4.52 5-19 5.89 - 5-43 5-50 5.79 6.311-60 1-80 2.08 1.8 1.92 1.95 2-04 2.23Kr. HBr. 13,Se. H,As. 1’. X.HI.5.59 5.77 6.05 6.40 - 6.18 6.101.98 2-04 2.14 2.26 2.2 2.19 2.21~ = 6 . 6N,. co. N,@. co,. 0,. NO,. I,. cos.5.63 5-63 5.73 5-62 Ortho- 7-77 a=4.80 4.09rhombic. 6 mols. b=7-25 a=98’per cell. c=9*782.00 1-99 2-03 1-99 4 mols. 1 mol.per cell. per cell.SiF,. ZrC1,. SiI,. GeI,. SnI,. CHI,.5.41 10.32 12.0 11.9 12-23 a=6*82= 2 ~ 5 . 1 6 = 2 ~ 6 * 0 = 2 ~ 5 * 9 5 =2X6.12 ~ = 7 . 5 2Effective 8 mols. 2 mols.radius of per cell. per cell.halogen 1.51 1-81 2.12 2.10 2.16 2-15The atomic diameters of the rare gases in the solid state are about0.75 of t h a t deduced from their gaseous properties, as pointed outby Kee~om.~l It is interesting to notice that the series Ne, -, -,H,N, H4C ; A, HCI, H,S, H,P; Kr, HBr, H,Se ; X, HI, with totalelectron number 10, 18, 36, and 54 respectively, have structureswith only slightly increasing lattice parameters.(The only excep-tions are hydrogen fluoride and water, which polymerise.) Theother tri- and poly-atomic molecules have similar structures withlarger cells and lower symmetry, but in these rotation takes placeat higher temperatures. Where the atoms are large, as in I,, COS,CHI,, SnI,, etc., the close-packing of the molecules gives place tothat of individual atoms. The case of nitrogen peroxide is stillin dispute. L. Vegard 444 finds 6 linear molecules of ON0 in a cell304 BERNAL AND WOOSTERS. B. Hendricks,445 from Vegard's measurements, finds 3plane molecules 0 o>N-N<OO. Other more complex molecularsubstances, Fe,(CO),, 455 and B10H14,456 have been studied butwithout much information on the nature of themolecules. Si(OCH,),,studied by W.Eulitz,457 shows a regular tetrahedral arrangementof OCH, about Si. Particularly interesting is the study of thevarious forms of sulphur and selenium and their solid solutionsby F. Halla, E. Mehl, and F. X. B o s c ~ , ~ ~ ~ ~ 461 pointing in everycase to an asymmetrical molecule 88 or Se,. Plastic sulphur hasbeen shown by J. J. Trillat and J. Forestier462 to have a fibrousstructure, a = 9-35 A,S. B. Hendricks46s has given an excellent survey of the present stateof knowledge of the structure of organic compounds. The essentialdifficulty in their analysis is that they are composed mostly of hydro-gen, carbon, nitrogen, and oxygen, the first of which gives no X-rayreflexion, whilst those of the other three are practically indistinguish-able.Some crystals, owing to simplicity or high symmetry, are suit-able for complete X-ray analysis, but the great majority are not, andneed to have their structures elucidated by means of a knowledgeof molecular form, interatomic distances drawn from other anaIyses,Raman spectra, etc., while for the orientation of the molecules. aknowledge of probable interactions of radicals and the informationgiven by cleavage, refractive indices, etc., is needed. Such analysescannot be used as authoritative except in the one important pointof molecular symmetry, which can be indubitably proved by X-rays.It is obviously necessary to proceed by a method of systematicresearch over the whole field, and this has been pushed forwardrapidly.A.Muller 470 has published another important paper on thehydrocarbons. Hydrocarbons of 11, 15, 17-21, 23, 24, 29, and30 carbon atoms were found to crystallise in the normal state (seeAnn. Reports, 1928, 25, 293), those of 5-10, 16, 18, and 20 carbonatoms in another form with smaller c spacing. Measurementsa t liquid-air temperatures and near the melting point show, first,that the coefficients of expansion are very different in differentdirections, C, = 0-00017, Cb =I 0.00005, CC < 0.00002, showingthat the expansion is nearly entirely due to the temperature affectingthe van der Waals forces between hydrogen atoms, the carbonchains exhibiting no measurable expansion.Secondly, the lateralanisotropy is very marked. The expansion is much greater on thea direction than the b, leading to a closer approximation to hexa-gonal close packing, as can be seen from the variation of the twoahortest intermolecular distances b and D : at liquid-air temperCRYSTALLOGRAPHY. 305atures, they are 4.9 and 4-35 ; at room temperatures, 4.9 and 4.46 ;a few degrees below the melting point, 5-0 and 448. Just belowthe melting point the two different distances give place to one at4-86, while in the liquid this increases to 5.2 A. These changesare no doubt due, first, to oscillations of the molecules about theirlong axes, a t higher temperatures to rotations while still in the solid,and finally, to translatory movements in the liquid.N. Fuchs 473has observed and photographed crystals of C,,H,,, on a liquid surfaceonly 1 molecule thick. The interfacial angles agree exactly withthose of Muller's hydrocarbons. The n-fatty acids and alcohols havebeen much studied, particularly by S. H. Piper and T. MalkinF7' T.Malki.13,~~~ and J. Thibaut and F. D. La and unsaturated long-chain compounds by J. Hengstenberg and R. K ~ h n . ~ ~ ' , 489Of other aliphatic compounds, three groups in particular havebeen studied in the last two years : (1) the amino-acids, peptides,and compounds containing the group R*CO*NH*R; (2) the sugars;(3) cyclohexane and its derivatives. The amino-compounds, whichhave been studied in connexion with the attempt to discoverthe structure of proteins (see this vol., p.332), are examples ofmolecular crystals where the chief cohesive forces are electrostaticbetween the negative carbonyl and the positive imino- or amino-radicals; hence the high densities and melting points. R. W. G.Wyckoff has redetermined the parameters of urea from absoluteintensity measurements; it is now one of the most exactly knownorganic structures. J. Hengstenberg and E'. V. Lene1491 and J.D. Bernal 492 have determined the structure of glycine. The mole-cules form sheets parallel to the cleavage. There is some evidencethat in the solid " zwitter-ions "332 C-K~ - are formed. + NH,Among other amino-acids studied by the latter are alanine,where the molecules NH3*CHMe*602 show a well-marked pseudo-plane of symmetry, and [CO,H*CH(PJH,)*CH,*S*],, I-cystine, where6 molecules with diad axes of symmetry are arranged in a spiralabout a six-fold screw axis.Of ring compounds, diket~piperazine,~~~diethylbarbituric acid,494 and spirohydantoin 495 have beenstudied.The sugars have been studied chiefly by J. Hengstenberg andH. Mark,496 K. Andress and L. Reinhardt,501 T. C. M a r w i ~ k , ~ ~ ~and E. G. Cells and space groups can be established, butthe difficulties of stereoisomerism and the absence of useful opticalindications owing to the preponderance of the hydroxyl effectshave prevented any trustworthy determination of structure. Every-306 BERNAL AND WOOSTER :thing points, however, to the existence of an almost plane ring0 7. 0. Hassel 504 has shown that cyclohexane is cubic, a = 8-41 c-0A., 4 molecules per cell, and the molecule must have ditrigonalscalenohedral symmetry 3.This points to a strainless alternatingHis later investigations (with H. Kringstad) 505 oftrans- 1 : 4-dibromo- and -di-iodo-cyclohexane show that these com-pounds also possess a centre of symmetry. The cyclohexanols havebeen studied by A. L. Patterson 506 and T. N. White,506, 507 butthe same difficulties occur as in the sugars.Aromatic compounds have been more studied than ever before,but, except for a few mentioned below, no information is furnishedas to molecular structure. The weight of evidence in favour of theplane ring is, however, increasing. (Mrs.) K. Lonsdsle 509 hasmade a determination of the structure of hexachlorobenzene byFourier analysis.Although the evidence for a flat ring is not asconclusive as in the case of hexamethylbenzene, the chlorine andcarbon atoms have been shown to lie in nearly a regular hexagon.(Miss) I. E. Knaggs 510 has shown that hexa-aminobenzene has atrigonal axis. A great number of substituted benzene compoundshave been examined by E. Hertel and K. S ~ h n e i d e r . ~ ~ ~ , 513 In allcases, space groups have been found, but while in some, e.g., trini-troresorcinol, the structure he proposes is in accord with the opticaldata, in others there are definite contradictions, and in still morethere is no evidence. The arguments relied on for suggestingstructures depend on considerations of packing, which, thoughthey may lead to correct structures, are not unambiguous.Of thethree dinitrobenzenes, m- has a plane of symmetry, p - a centre,and 0- is asymmetric. 2 : 4 : 6-Tribromobenzonitrile has a planeof symmetry.Thetwo rings lie in a plane which is slightly tilted to the (100) planes.This orientation, predicted by K. Banerjee 517 from optical andmagnetic data, has been accepted by J. M. Robertson 518 and (Sir)W. Bragg, who had found similar atomic positions but had con-nected them wrongly in molecules, thus arriving a t a structurewith puckered rings.516 This is an excellent example of the im-portance of using optical methods for organic crystals.The stilbene-azobenzene series has been much studied ; theevidence points to a planar straight double ring, C,H,*X*X*C,H,.Graphite seems to be the last product in the condensation of benzenerings.U. Hofmann and A. Frenzel 524 have shown that graphitecrystals can be oxidised reversibly to graphitic acid without change/c\ring.The structure of naphthalene is now fairly well establishedCRYSTALLOGRAPHY. 307in the prismatic spacings of the lattice (i.e., without altering thebenzenoid nets), but with a change in the c spacing from 3-4 to6.9 8., and then by hydration to 11.3 d. This is by far the largestreversible change in crystal structure ever observed.E. Hertel526-530 has done valuable work in examining a largenumber of molecular compounds among organic substances. Ingeneral, they have cells bearing simple relations to those of theircomponents. The X-ray method is coming more and more into usefor the identification of organic compounds; it has the additionaladvantage of giving as well the maximum molecular weight.Forinstance, K. Bruckl533 has proved the identity of the alkaloidsbanisterine and harmine, C,,H,ON,, in this way, and it can beapplied just as easily to complicated compounds of unknown com-position and structural formula.The application of X-ray methods to the study of colloids andfibres and to biological problems is dealt with in another part ofthis volume (p. 322).The following is a list of the chief papers on the X-ray analysisof crystals published in 1930 and 1931. Papers containing suchmeasurements incidentally and not leading to cell or space groupare omitted, and others may have been overlooked.The papersare arranged according to the classification of substances used inthe text :A. Metallic compounds. (1) Elements. (2) Intermetallic com-pounds and systems of transition metals. (3) Interstitial com-pounds. (4) Compounds of transition and B-group metals, andsemi-meta.ls.B. Ionic compounds. (5) Simple oxides and hdides. (6) Anhy-drous salts. (7) Hydrates and co ordination compounds. (8)Complex oxides and hydroxides.C. MoZecular compounds. (10) Simple molecular compounds.(11) Long-chain compounds. (12) Other aliphatic compounds.(13) Aromatic compounds.In each group, compounds belonging to recognised types aregiven first. These are designated by the letters used for them inthe “Strukturbericht.” Next comes a list of new or uncertainstructures, and finally in the sections on metals a list of systemsexamined by X-rays, whether these contain definite compoundsor not.Asterisks attached to the reference number give some indicationof the kind of investigation: ** signifies a complete structuredetermination giving atomic positions determined by intensitymeasurements, * a determination giving cell and space group.Absence of a mark usually refers to simple powder photographs.(9) Silicates308 BERNAL AND WOOSTER :3 .Interstitial compounds.Known types : 12a,4. TiH, TiH,, Zr,H, ZrH, Pd2H.12b,4. Ti,H, Zr2H, Ta2H.8a,4. TaH.141, 143.lZa,6. Mn4N, Fe,N, Mo,N, W,N, ScN, TIN,VN, CrN, ZrN, NbN, ScC, Tic, VC, ZrC,NbC, MoC, TaC.140, 141.lZb,G.Cr2N, Mn2N, Fe,N, Pe3N, V2C, Mo,C, Ta2C.w2c.8b,6. MoN, MoC, WC.1409 141.(Hagg's notation : see p. 293.)New structures : Fe,C (martensite) 144*, 145*, 1479 148 ; Fe,CFe2N, Fe3N w2** ; VC,, La, Ce, Pr, Nd, C,, UC,, ThC, 244, 245.(cementite) 146**, 147, 149** ; Pe2B 159, 160, 161*, FeB, Fe,P,Systems : Pt-He 137 ; Pd-H 138 ; Fe-N 151-155 * Cr-C 156,157 * V-C 158,Pe-V-C 158 ; Fe-W-C 150 ; Fe-B 159, 160 ; T i - 6 0 161.4. Metallic compounds of B-group metals, semi-metals, and sulphides,etc.Known types : A4. Xi 200. A9. C 201. €33. Sic 202.Bl. SnSb lg5. B13. NiS (millerite) 205**. 6'18.FeS, (marcasite) ,06**.D82. Cu5Zn,, Cu5Cd8 lG8** ; Ag5Hg8 172 ; I?:e6Zn2,,CO~Z~Z,, Ni5Zn2,, Rh5Zn,,, Pd5Zn2, l G F .0 8 3 .Cu7Hg6 173, 174 7 * Ni 5 Cd 2 1 166.D84, Pt,Zn,, l G 6 .(y-Structures)(p-Mn Xtrzccture) CoZn 166 ; Cu,Si l80CRYSTALLOGRAPHY. 309New structures : AgLi, AgLi, ; TiAI, 177 ; p-CuAl 178 ;C~23AI21 179* ; FeSi 181** ; Cu15Si, l80 ; Cu,Sn lS2 ; CUgAs,1*6Cu,As lM, lS5 ; Au2Bi lg2 ; Ag2S u)4 ; CdSb, Cd,Sb, 194 ; BiSe,Bi,Se, ls7 ; Bi,Te, 198 ; Cu,(FeGe)S, (germanite) 207 ; Mg2N2.1gySystems : Cu-Li 163 ; Ag-Li 164 - , Fe, CO, Ni, Rh, Pd, Pt-Zn,Ni-Cd 165, 166 ; &-Zn 169 ; Ag-Cd 171 ; cu-~g 173, 174 ; Ag-Hg 172 ;Ti-AI 177 , - Mn-& 130, 176 ; Fe-M 175 ; &-& 178, 179 ; h-si 180 ;Ag-Sn lS9 ; Au-Sn 183 ; Ni-Bi 190 ; Cu-As 184 ; &-Sb 187 ;Cu-Bi lgl ; Ag-As, Ag-Sb, Ag-Bi 188 ; Au-Sb 189 ; Cd-Sb 193,194 ;Sn-Sb lg5 ; Sn-Bi 196 ; Bi-Se, Pb-Bi lS7 ; Bi-Te lS8.5.Ximple ionic compounds.Known types: BI. LiH, NaH, KH, RbH, CsH 208**; NaCN,B2. CsCN 209. C3. Cu,O 231. C9. SiO, 237. D51.C6. MgBr,, MnBr,, FeBr,, CoBr,, MnI,, FeI,,C O I , . ~ ~ ~ C19. CdCl 2 F * * , 216.New structures : AgI (above 146") 213 ; AgCN 211* ; PbCl, 221*, 222 ;HgBr, 223** ; MF, 224; FeF,, RhF,, PdF, 225* ; CeF, 226** ;(Mn,Fe),O, (bixybite) (C-sesquioxides) 235**, 236 ; ZrO, 238 ; CrO,S O * , 242* ; M003241**, 242** ; WOSa2* ; Mg,N,lg9*.Systems : LiH-LiF 208 ; NaCN-NaCl, NaBr, NaI ,09 ; NaC1-AgCl ; CuI-AgI 212 ; LiBr-MgBr, ; CaF,-SrF, 215 ;CaC12-MIIC12 (M = Co, Fe, Mn, Cd) 215 ; M1llO-M,IIO, M;I( OH),-M,II(OH), (MI1 = Mg, Ca, Mn, Co, Ni, Zn, Cd) 220; E'e,O,-Cr203, Fe,O,-Mn,O, 233 ; Th-Th02.239KCN, RbCN ,09* ;Fe20,.234 0 5 2 .L&203.2359 236.AICI, 227 ; CrCl 3 228** ; AsI, 229*, 230** ; SbI,, BiI, 229* ; NiO 232,6. Anhydrous salts.Known types : C11. CaC2**, SrC,, BaC,, La, Ce, Pr, NdC, 244.GI. CoCO, 257 ; (Ca, Mn)CO, 255. GZ. KNO 3 ;H2. KMnO, 269**. H3. CaCrO, ,'l**. H4.H22. KH,P04 282***.SrCO,, BaC0,.258BaW0273**.New structures : CaB,, SrB,, BaB, 245; NaHC,, KHC, 244* ;T1HF,249;RbN 3 247,248*; Ba(N,),=**; Pb(N,),S6; Hg(CN0),246;NH4C102*, AgClO,, Ca(C102)2, et~.,~O; NaNO, 251** INa,S0,253**; LiIO, 254** ; BaCa(C03)2.256Polymorphism of NaNO326o** ; KNO, 262 ; RbNO, 263 ;(NH,)NO, 259*.Fluocarbonates : RFCO, (bastnaesite), BRFCO,, CaCO,(parisite), RFCO,,CaCO, (synchisite), SRFCO,, BaCO,(cordylite) (R = La, Ce, Pr , . .)264**310 BERNAL AND WOOSTER :a-NaClO, 2 6 5 3 266* ; a-(NH,)ClO, 265; p-(cubic)-RClO, (R = Na,AgMnO, 270* ; SrCrO, 271 ; PbCrQ, 272 ; KBF, 274 ; Na2S04 277:g ;polymorphs of Na,SO, 275 ; Ag2S04 276* ; K2S04 278* ;K2Cr04 279*, ,go** ; (NH,),CrO, 281* ; Ca,P(PO,), (apatite) 283:kx:9""' ; AgHgI, 285* ; KPF,, NH,PF6, CsPF6 286 ; Na3NF6 ;(NH,),&F, 288*, 289* , - K,Cr207, (NH,),Cr207 290*, 291 7 - K,S206Group : CaCrO, (crocoihe), Ca1206 (lautarite), CaI,O,,CaCrO,Systems : HgSO,-HgCl,, HgS02-Hg12.295 Reactions between7.Salt hydrates, co-ordination compounds, etc.Known type : H41. (NH4)2CuC1,,2H,0.301New structures : CuS0,,5H20 (dehydration of) 297 ; CaS04,2H20(gypsum)298 * *, CaHPO, ,2H,O (brushit e) , Ca,S O4,CaHP0,,4H,O(ardealite) 299* ; BeS0,,4H20 ,0°** ; M11X2(H,0)6 (M = Ca,Sr, Ba; X = C1, Br, I) ,02; M11M1VX,1(H20)6 (MI1 = Mg,Mn, Fe, Ni, Co, Zn ; MIJ' = Si, Ti, Zr, Sn, P t ; X = P,Fe, Co .. .) ,04**; M21M11(X04),,6H,0 (MI = K, NH,,T1, etc.; MI1 = Mg, Fe, Zn, Cd, etc.; X = S, Se, etc.) ,05*,,06** ; K3M111(CN), (MIII = Cr, Mn, Fe, Ir) 307* ; K,PbMII(NO,),,K3Mn(N0,),,3H,O(M = Cu, Ni . . .) 308; ~ a ~ 0 2 ( ~ ~ 3 * ~ ~ * ~ (H*COO),Cu,2H20 and 4H20 310, 311 ; C(NH,),Cl 312'k ;(SMe,),SnCI,, (SMe,Et),SnC16, (PMeEt,),SnC1,.313*Ag, NH,, K, Rb, CS, T1) 26'*3 2'8*.292**, 293*.(dietzite) 294*.solid salts.296c1, Br, I), M11M'1'(c~)6(NH3,H20)6 (Jf'I = Co . . .; MIn = Cr,8. Complex oxides and hydroxides.Spinel type : H I I . General 325, 326, 327 ; MgA120, 329** ; MgFe,O,,MgGa,0,330** ; ZnFeO,, CdFe,O, 333 ; MgCr,O,, CdCr,O, 334 ;CuA1204, ZnAl,O,, ZnCr,O,, ZnFe,O,, MnFe20, 335 ; ZnGa20, 331 ;Co2Ti04, ZqTiO, 336 ; Mg,TiO,, Co,Ti04, Zn,TiO,, Mn2Ti0, 337 ;Ni,GeO, ; Zn,Ti04, Zn,SnO, 339.y-Alumina type : y-A1203 324 ; Fe,O, (magnetic) 328**.Hausmannite type : CdIn,O,, CaIn204.x0*Related structure : Na2~,,O3, (p-alumina) 345** ; Ca,AI,06 346* ;Ilmenite type : (74.NiTiO, 339 ; FeTi0,.343Related structures : (Fe,Mn)(Nb,Ta),o, (columbite) 341'g* ;Perovskite type : G5. (Ca,Ce,Na),(Nb,Ti),06 (10parite).~~~*Pyrochlor type : (Na,Ca),Nb,O,(O,OH,F) (pyrochlorite) 349* ;CaFe,0,,CdFe20,, (Sr,Ba,Pb)Fe,O, .32Fe,TiO ( pseudobrookite) .342* *(Ca,Mn,Na,),Sb,07 (atopite and mauzelite) 356* CRYSTALLOGRAPHY. 31 1Garnet type : H31.NnCa2~As301, (berzeliite) 358* ;Na,Li ,M2F 12(cryolithionite) .359*Complex hydroxides : AlO( OH),FeO( OH),MnO( OH) 3193 3207 321 ;Fe,0,,4H,0322 ; Be,BO,(OH) (hambergite) 344*:k ; K, Fee*, Fe"',Al(S0,) (OH),H,O (voltaite and similar compounds) 3529 353 ;xPbCl,, yAgC1, xCu( OH), (boleite, pseudoboleite, cumengite) 348 ;Mn3(As04),,ZMn ( OH), (arsenoclasite) .,55Systems : Ba(OH),-H,O, NiO-Ni,O,-H,O, FeO-Fe,O,-H,O 314 ;Al,O,-H,O ; V,O,-K,O, Nb,05-H,0, Ta,05-H,0 323 ;MgCO,-Mg(OH),-H,O 351 ; Zn(OH),-ZnX,-H,O (X = C1, Br, I,NO,, $30,) 350 ; Mg0-Fe0-Fe,0,332 ; CaA1,04-H,0 347 ; Fe,O,-CUO-SO~-H~O.~~9. Xilicates.General , 6 0 3 361 ; germanates 338.Orthosilicate types : Ni,Si04, olivine type 339 ; Bi,(SiO,),(eulytite) 362** ; CaTiSiO, (titanite) 363** ; Al,SiO, (cyanite,sillimanite, andalusite) (revision) 365** ; Mn7SiO12 ( b r a ~ n i t e ) .~ ~ ~Polysilicate types : Sc,Si,O, (thortveitite) 366** ;(melitite) 367** ; Ca,ZnSi,O, (hardystonite) 368:k ;(meliphanite) 369* ; CeloAl,(Mg,Fe),Si,0,4( OH), (vesuvi-anite) 370** ; H,XYgB3Si6031 (tourmahe) 3713 372 ; BaTiSi,O,(benitoite) 373** ; (Na,Ca,Fe)6ZrSi,018(OH7Cl) (e~dialite).,~*Metasilicate types : CaSiO, (wollastonite) , HNaCa,( SiO,), (pect-Monoclinic pyroxenes : XY(SiO,), (diopside) (X = Ca, Na ;Y = Mg, FeIII, Az) 376**; XY(SiO,), (clino-enstatite) (X = Li,Mg; Y = Mg, Al).376**(Ca7Na)2(Mg>Az) (si,Al)20 7(Ca,Na),Be(Si,Al),( O,OH,F),olite).375*, 376*Rhombic pyroxenes : (Mg,Fe) (SiO,), (enstatite) .377**8 378*Monoclinic amphiboles : H,Ca,Mg,(Sio,), (trem~lite).~~~**Rhombic amphiboles : H,Mg,(SiO,) (anthophyllite) 380** ; otherSerpentine : H4Mg3Si209 (chrysolite) .384**Mica types : Micas; K&U4010(OH,F), (X = Mg, FeII, FeIII,MnII, MnIII, Ti, Li ; Y = Si, A1 ; n = 2-3) ; Ca&Y,Olo(OH,F),(brittle micas) 385* ; KAl,(Si,Al)Olo(OH), (muscovite).386**Chlorite8 : X,Y,0,0(OH)8 387* (kaolins) ; A12Si2010(OH)8 388-391 ;H8KCa,Si8020(OH)8F (apophyllite) 392** ; Be,SiO, (phenakite),Zn,SiO, (willemite) 393** ; (MnFe,)Si,O,( OH,Cl), (pyrosma-lite) 394 ; AlBeSiO,(OH) -(euclase), Ca,BSiO,(OH) (datolite) 395* ;A1,(A1,Fe)Ca,(Si04),(OH) ( e p i d ~ t e ) .~ ~ - ~ ~ *a m p h i b ~ l e s . ~ ~ l - ~ ~ ~ 312 BERNAL AND WOOSTER :Felspar types : CaB,Si,O, (danburite) 399** ; (Ca, Na, K) (Si,Al),O,(felspars) .m*Nepheline type : X2Y2Si,08 (X = Li, Nay K ; Y = A, Sc, Y,La, Nd, Pr, Sm, Er) 4019 402* ; NaAlSiO, (nepheline) 403*9 ,04* ;KAlSiO, (kaliophilite) 404*9 405* ; NaASi,06,H20 (analcite) 403,Zeolites 411 ; Na4A13Si301,C1 (sodalite), (MnYFe,Zn),Be3Si30,,S406**, 407**, 408*, 409 ; L ~ S i 4 0 1 0 (petalite),410”(helvine) ,12* ; Na2Al,Si30,,,2H,0 (natrolite) 41% 413*y 414 ;(scapolite) 411*9416 ; (Na,Ca),A1,Si,01,(C03,S04,C1) (davyne) ,l1*9417 ; (cancrinite) 411*9 4179 418 ; (Na,Ca)Al,Si7018,6H20 (heul-andite) 4149 415* ; CaAl,Si401,,6H,0 (chabazite) 419*, 420; otlirrhydrous silicates : ~ h a m o s i t e , ~ ~ ~ pyrosmalite.422*Silicate systems and synthetic silicates : Fe,O,-SiO, 425 ; Cr,O,-SiO, 423 ; MgO-SiO, 425 ; K,O-CaO-SiO, 424 ; CaO-Si0,-H,O 431 ;p-CaSiO, 428 ; y-Ca,Si04, Ca,SiO,, Ca3Al,06 429 ; Ca,Si04 430;gla~ses.43~~ 433(Na>Ca)4M3(AlYSi )Ssi So,,( clY s047c03)10.Simple molecular compounds.Known types : AI. Ne 435 ; Kr 4369 437 ; Xe 438 ; HC1, HBr(high) 440. A3. H, (~ara).~39C2. CO,, N 2 0 F ClO. H20.458y459Dl. PH,, ASH,.^^, D I I . SiI, 451 ; ZrC14.452*01. CH4.4489 &’** 011. CH13.449aNew structures : HCI, HBr, HI (low) 440 ; H,S, H,Se 441*9 442 ;NO, 444*, 445 ; COS 447* ; SiF, 450** ; UCl, 452 ; Fe3(CO),, 455* :B,0H1,456 ; C(CH,*O*CHO),, pentaerythritol tetraformate 4533(explosive) .466454* ; Si(OCH,), 457** ; S, Se 460,461*, 462,463 ; p 464, 465 ; SbOrganic.-General .4611. Long-chin compounds.Paraffins 4699 470**~ 471, 729 , 7 4 4 ~ 3 ; C3,H7, (2-dimensional crys-tals 473 ; n-fatty acids 4779 ,789 4793 4809 481 ; dicarboxylicacids482* ; alcohols C,H,+,NH,I (n = 4-12) 485**, 486**,489** (rotation).Unsaturated chains : CHBr,*CBr:CBr*CHBr, 4** ;CH,*O*CO[*CH:CH*C( CH3):CH*],CH:CH*CO*OCH3,methyl bixin 487* ; C6H5*[CH:cH],*C6HS, diphenylpolyenes488**.12. Other aliphutic compounds.Amino-compounds : (NH,),CO, urea 490** ; NH,*CH,*CO,H,glyche 491**~ 492* ; amino-acids 492* ; peptides 492*, 493 ; di-ketopiperazine 492* ; diethylbarbituric acid 494* ; d + dZ-spiro-hydai~toin.~~~:CRYSTALLOURAPHY. 313Sugars : d-glucose 49G*, 497* ; d-laevulose 496* ; mannitol, dulcitol,mannose 4987 499*3 500* ; arabinose, xylose, rhamnose 501*a 502* ;lactones and pyranoses.503*cyclo-Hexane derivatives : cyclohexene, trccns-dibromocyclo-hexane 504, 505* ; quebrachitol, inositol, quercitol 504*, 505*95m* ; ~yclohexanediols.~06*~ 507*13. Aromatic cornpounds .Benzene, thiophen 508 ; hexachlorobenzene 509*** ; hexa-amino-benzene 510 ; 1 : 3 : 5-trinitrobenzene, 2 : 4 : 6-trinitrotoluene 527 ;picric acid 511 ; trinitroresorcinol, trinitrophloroglucinol 512* ;lead styphnate 246*; o-, m-, and p-dinitrobenzene, 4 : 6-di-nitroxylene, 2 : 6-dinitrophenol 513* ; 2 : 4 : 6-tribromobenzo-nitrile 514* ; m-iodobenzoic acid 515** ; naphthalene and anthr-acene 516**7 517**9 518 ; azobenzene 520 ;p-nitrostilbene 521* ; diphenyl, dimesityl, dl-3 : 3’-diamino-dimesityl, hexachlorodiphenyl, diphenic acid, o-tolidine 522,523 ; naphthacarbazole 531* ; aniline picrate, 2 : 4 : 6-trinitro-diphenylamine 529* ; tetrabromo-a- and - p-naphthylamine 530 ;triphenylbismuthine dichloride 525* ; strychnine 532* ; harmine533* ; graphite and graphitic acid 5232 524 ; other complex organiccompounds 531,534 ; molecular compo~nds,519*, 526*, 527*, 52% 530*lol J.C. McLennan and R. M’. McKay, Trans. Roy. SOC. Canada;, 1930, iii,24, 111, 33; A., 413. lo2 J. C. McLennan and R. J. Monkman, ibid., 1929,iii, 23, 111, 255; A., 1930, 533. lo3 M. C. Neuburger, 2. anorg. Chem., 1931,197, 219; A., 671; 27. Krist., 1931, 78, 164; A., 1217. lo4 W. A. Wood,Phil. Mag., 1931, [vii], 12, 853. lo5 K. Sasaki and S. Sekito, J. SOC. Chem.Ind. Japan, 1930, 33, Suppl. 11, 482. lo6 H. Hartmann, F.Ebert, and 0.Bretschneider, 2. anorg. Chem., 1931, 198, 116; A., 805. lo‘ J. C. McLennanand R. W. McKay, Trans. Roy. SOC. Canada, 1930, iii, 24, 111, 1 ; A., 413.loB E. ohman, Svensk Kem. Tidskr., 1930, 42, 210; A., 1930, 1503. lo9 C.Agte, H. Alterthum, K. Becker, G. Heyne, and K. Moers, Natumiss., 1931,19, 108; A., 288.ll1 G. Mayer, 2. Krist., 1929, 70,383; A., 1930, 140. 112 A. E. van Arkel and W. G. Burgers, 2. Metallk.,1931, 23, 149; A., 896. 114 G.Bredig and E. S. von Bergkampf, 2. physikal. Chem., Bodenstein Festband,1931, 172; A., 1217. 115 F. 31. Jaeger and J. E. Zanstra, Proc. K . Akad.Weten8ch. Amsterdam, 1931, 34, 16; A., 791. 116 S. Sekito, 2. Krist., 1930,74, 189; Chem. Zentr., 1930,ii, 1945; A., 288. 117 0. Weinbaum, 2. Metallk.,1929, 21, 397; A., 1930, 149.118 N. Ageev and G. Sachs, 2. Physik, 1930,63, 293; A., 1930, 1510; Mitt. deut. Materialpriif. Berlin-Dahlem, 1930, No.13, 50; Chem. Zentr., 1931, i, 1065; A., 794. llD D. Stockdale, J . Inst.Metals, 1931, 45, 127 ; A., 556.120 S. Tanaka and C. Matano, Mem. Coll. Sci. Kyoto, 1930, [A], 13,343 ; A . ,1930, 1509. l 2 2 0.Eisenhut and E. Kaupp, 2. Elektrochem., 1931, 37, 466; A., 1118. 123 J. L.Haughton, R. J. M. Payne, and G. D. Preston, Inst. Metals, 1931; A., 1224.124 N. S. Kurnakov and N. V. Ageev, ibid.; A., 1224. 125 2. Physik, 1930,anthraquinone 519* ;K. Moeller, ibid., p. 575; A., 1001.113 S. 13. Kendricks, 2. Krist., 1930, 73, 376.121 G. Sachs and J. Weerts, 2. Physik, 1930, 60, 481314 BERNAL AND WOOSTER :63, 210.126 Ibid., 64, 359. 127 Ann. Physik, 1930, [v], 5, 762; 6, 458;7, 408; A., 1930, 1510. 128 E. Persson, 2. physikal. Chem., 1930, [B], 9, 25.130 T. Ishiwara, Sci. Rep. Tdhoku I m p , Univ., 1930, 19, 499; A., 296.131 W. G. Burgers and J. C. M. Basart, 2. Krist., 1930, 75, 155; A., 414.132 0. L. Roberts and W. P. Davey, Met. and Alloys, 1930, 1, 648; A., 150.133 A. Osawa, Sci. Rep. l'dhoku I m p . Uniu., 1930, 19, 109, 247. 134 S.Nishigori and M. Hamasumi, ibid., 1929, 18, 491; A., 1930, 419. 135 S.Sekito and Y. Matsunaga, J . Study Met., 1929,6, 229; A., 1930, 1245. 136 E.Keunecke, 2. Elektrochem., 1930, 36, 690; A., 1930, 1380. 137 H. Damiano-vich, Anal. ASOC. Quim. Argentina, 1929, 17, 95; A., 1930, 435. 138 G.Tammann, 2. anorg.Chem., 1930, 188, 396; A., 1930, 699. 139 A. Westgren,Xvensk Kem. Tidskr., 1930, 42, 193; A., 1930, 1351.140 2. physikal. Chem., 1929, [B], 6, 221 ; A., 1930, 147. 141 .XvensJc Kem.Tidskr., 1931, 43, 187; A., 1215. 142 2. physikal. Chem., 1931, [B], le, 33;A., 414. 143 Ibid., 11, 433; A., 413. 144 Nature, 1931, 127, 270; A., 415.145 2. Physsik, 1930, 64, 325; A., 1930, 1355. 146 2. Krist., 1930, 74,534; A., 415. 147 S . Sekito, Sci. Rep. TGhoku I m p . Univ., 1931, 20, 313, 369.148 K. Tamaru and S. Sekito, ibid., p. 377. 149 Proc. I m p . Acad. Tokyo, 1930,6, 269; A., 1930, 1351.151 G.Hiigg, 2. physikal. Chem., 1930, [B], 8, 455; A., 1930, 1097. 152 0. Eisenhutand E. Kaupp, 2. Elektrochem., 1930, 36, 392; A., 1930, 996. 153 S. Epstein,H. C.Cross, E. C. Groesbeck, and I. J. Wymore, Bur. Stand. J . Res., 1929, 3,1005; A., 1930, 419. 1 5 4 P. H. Emmett, S. B. Hendricks, and S. Brunauer,J . Amer. Chem. XOC., 1930, 52, 1456; A., 1930, 699. 155 S. Brunauer, 31. 3:.Jefferson, P. H. Emmett, and S. B. Hendricks, ibid., 1931, 53, 1178; A., 799.lSa A. Westgren and G. Phragmen, 2. anorg. Chem., 1930,187, 401 ; A., 1930,681. 157 K. Hatsuta, J . Study Met., 1931, 8, 81; A., 1005. 15* M. Oya,Xci. Rep. Tdhoku I m p . Uniu., 1930, 19, 449; A., 297. 159 F. ?Tevcr, 2. tech.Physik, 1929, 10, 137; A., 1930, 148.1931, [B], 12, 413;A., 151, 896. 161 L. R. Brantley, 2. Krist., 1931, 77, 505; A., 780;J. Amer. Chem. Soc., 1930,52,3956. la2 Z.Krist., 1930,74,511 ; A., 415. la3 S .Pastorello, Gazzetta, 1930, 60, 988; A., 296.164 Idem, ibid., 1931, 61, 47;A., 418. 113~ Arkiu Kemi, M i n . Geol., 1931, 10, [B], No. 11; A., 900.166 W. Ekman, 2. physikal. Chem., 1931, [B], 12, 57; A., 418. 168 Phil.Mag., 1931, [vii], 12, 143; A., 896. 169 (Miss) C. F. Elam, Inst. Metals, A.,1930, 536.170 G. Tammann and H. J. Rocha, 2. anorg. Chem., 1931, 199, 289; A , ,1223. 171 C. W. Stillwell, J . Amer. Chem. SOC., 1931, 53, 2416; A., 901.172 A. J. Murphy and G. D. Preston, Inst. Metals, 1931; A., 1224. 173 N.Katoh, 2. physikal. Chem., 1929, [B], 6,27 ; A., 22. 174 N. Katoh, Bull. Chem.SOC. Japan, 1930, 5, 13; A., 1930, 400. 175 W. L. Flink and K. R. VanHorn,Amer. Inst. Min. Met. Eng. Tech. Pub., 1930, No. 351; A., 158. 1 7 6 A. J.Bradley and P. Jones, Phil.Mag., 1931, [vii], 12, 1137. 177 W. L. Flink,I<. R. Van Horn, and P. M. Budge, Amer. Inst. Min. Met. Eng. Tech. Pub.,1931, No. 393; A., 676. 1 7 8 I. Obinata, Mem. Ryojun CoZZ. Eng., 1931, 3,285, 295; A., 676; Nature, 1930, 126, 809; A., 33. 179 G. D. Preston,Phil. Mag., 1931, [vii], 12, 1980.180 S. Arrhenius and A. Westgren, 2. physikal. Chem., 1931, [B], 14, 66;A., 1223; lslH. Moller, Natumoiss., 1930, 18, 734; A., 1930, 1351; F. Weverand H. Moller, 2. Krist., 1930, '95, 362 ; A., 549. lE2 J. 0. Linde, Ann. Physik,L. J. Wood, J . Amer. Chem. SOC., 1930, 52, 3833; A., 1930, 1510.150 W. A. Wood, Phil. Mag., 1930, [viii], 10, 659; A., 1930, 1503.160 G. Htigg, 2. physikal. Chem., 1930, [B], 11, 152CRYSTALLOGRAPHY. 3151931, [v],:8,124; A ., 414. 183 S. Stenbeck and A. Westgren, 2. physikul. Chem.1931, [B], 14,91; A., 1223. 194 N. Katoh, 2. Krist., 1930,76,228; A., 418;Bull. Chem. SOC. Japan, 1930, 5, 275; A., 1930, 1509. lE5 F. Machatschki,Centr. Min., 1930, [ A ] , 19; Chem. Zentr., 1930, i, 1918; A., 1930, 1352.l a 6 Idem, Jahrb. &fin., 1929, [A], 59, 137; Chem. Zentr., 1929, ii, 1639; A.,1930, 280. 187 E. V. Howells and W. Morris-Jones, Phil. Mug., 1930, [vii],9, 993; A., 1930, 849. la8 S. J-. Broderick and W. F. Ehret, J . PhysicalChem., 1931, 35, 2627, 3322; A., 1223. 1139 0. Nial, A. Almin, and A. West-gren, 2. physikal. Chem., 1931, [13], 14, 81; A., 1223.lS0 G. Hagg and G. Funke, ibid., 1930, [B], 6,272 ; A., 1930, 284. lS1 w. F.Ehret and R. D. Fine, Phil.Mag., 1930, [vii], 10, 551; A . , 1930, 1503-192 W. J. de Haas and F. Jurria,anse, Natumuiss., 1931, 19, 706; A., 1224.193 M. Chikashige and T. Yamamoto, Chikashige Anniv. Vol., 1930, 195; A.,671. 19* F. Halla and J. Adler, Z. anorg. Chem., 1929, 185, 184; A.,1930, 147. 195 E. G. Bowen anti W. Morris-Jones, Phil. Mag., 1931, [vii],12, 441; A., 1118; Nature, 1930, 126, 846; A., 33. lS6 D. Solomon andW. M. Jones, Phil. Mag., 1931, [vii], 11, 1090; A . , 676. l S 7 N. Parravanoand V. Caglioti, Gazzetta, 1930, 60, 923; A., 296. F. Korber and U.Haschimoto, 2. anorg. Chem., 1930, 188, 114; A., 1930, 681. lS9 G. Hagg,2. Krist., 1930, 74, 95; Chem. Zentr., 1930, ii, 1033; A., 549.200 A. G. Nasini and A. Cavallini, Atti III Cong. Nuz. Chim., 1929, 463;Chem.Zentr., 1931, i, 2163; A., 1001. 201 M. Hirata, Sci. Papers Inst. Phys.Chem. Res. Tokyo, 1931, 15, 219; A., 1002. 202 H. Briikken, 2. Krist.,1930, 75, 572; Chem. Zentr., 1931, i, 213; A., 549. 203 Amer. Min., 1929,14, 470; A., 1930, 671. 204 J. Palacios and R. Salvia, Anal. Pis. Quim.,1931, 29, 269; A., 789. 205 N. H. Kolkmeijer and A. L. T. Moesveld, 2.Krist., 1931, 80, 91; A . , 1265. 206 Amer. Min., 1931, 16, 361. 207 W. F.de Jong, 2. Krist., 1930, 73, 176; A., 1930, 1352. 208 2. physikal. Chem.,1931, [B], 14, 265; A., 1358. 209 Gazzetta, 1931, 61, 191; A . , 789.210 M. le Blanc and J. Quenstkidt, 2. physikal. Chem., 1930, 150, 321; A.,1930, 1511. 2 1 1 H. Briikken, Norslc Videnskabsselskab., PGhr. 11, 1929, 48,169. 212 G. Lunde and P.Rosbaud, Z . physikul. Chem., 1929, [B], 6, 115;A., 1930, 149. 213 R. Bloch and H. Moller, ibid., 1931, 152, 245; A . , 444.214 A. Ferrari and C. Colla, A t t i R . Accad. Lincei, 1931, [vi], 13, 78; A., 901.215 E. Rumpf, Z. physikal. Chem., 1930, [B], 7, 148; A., 1930, 537. 216 A.Ferrari, Atti 111 Cong. Naz. Chim,., 1929, 4, 52; Chem. Zentr., 1931, i, 2162;A., 1001. 217 L. Pading and J. L. Hoard, 2. Krist., 1930, 74, 546; Chem.&372tT., 1930, ii, 2103; A., 414. A. Ferrari and F. Giorgi, A t t i R. Accad.Lincei, 1929, [vi], 9, 1134; 10, 522; A., 1929, 1369; 1930, 400. 219 A. Fer-rariand A. Inganni, ibid., 1929, [vi], 10, 253; 1930, [vi], 12, 668; A., 1930,285; 1931, 901.220 G. Natta and L. Passerhi, Atti III Cong. Naz. Chim., 1929, 365; A.,1005.222 Bull. Xoc. chim.,1929, [iv], 45, 1002; A., 1930, 138. 223 2. Krist., 1931, 77, 122; A., 671.234 A. Ferrari and A. Scherillo, Gazzetta, 1929, 59, 927; A., 1930, 400.22s F. Ebert, 2. anorg. Chem., 1931, 196, 395; A., 549. 226 I. Oftedal, 2.physikul. Chem., 1931, [B], 13, 190; A . , 1002. 227 V. E. Laschkarev, 2.anorg. Chem., 1930, 193, 270; A . , 1930, 1503. 228 N. Wooster, 2. Krist.,1930, 76, 363.230 D. Heyworth, ibid., 75, 574; A., 549; Physical Rev., 1931, [ii], 38, 351;A., 1115. 231 M. C. Neuburger, Z. Krist., 1931, 77, 169; A., 671 ; 2. Physik,1931, 67, 845; A., 549. 232 0. G. Bennett, R. W. Cairns, andE. Ott, J . Amer.ohem. Soc., 1931, 53, 1179; A., 549. 233 P. E. Wretblad, 2. anorg. Chem.,221 Proc. Roy. Soc., 1931, [A], 132, 266; A ., 1001.229 H. Briikken, ibid., 74, 67; A., 549316 BERNAL AND WOOSTER :1930,189, 329; A., 1930, 849. 234 T. Katsurai and T. Watanabe, Sci. PapersI m t . Phys. Chern. Res. Tokyo, 1930,13, 89; A.,1930, 846. 235 2. Krist., 1930,75, 128; A., 415. 286 Ibid., 1929, 70, 187; A., 1930, 139. 237 L. Krejciand E. Ott, J. Physical Chem., 1931, 35, 2061; A., 909. 238 W. M. Cohnand S. Tolksdorf, 2. physikal. Chem., 1930, [B], 8, 331; A., 1099. 239 W. G.Burgers and J. A. M. van Liempt, 2. anorg. Chem., 1930,193, 144; A., 1930,1538.240 Nature, 1931, 127, 782; A,, 789. 241 N. Wooster, ibid., p. 93; 1931,128, 35; A., 289, 897; 2. Krist., 1931, 80, 504. 242 Ibid., 78, 484; A., 1115.244 Naturwiss., 1930, 18, 305; 2. physikal. Chem., 1930, [B], 9, 437; A., 1930,Ci72, 1351.245 2. Elektrochem., 1931, 37, 542; A., 1218. 246 F. D. Miles,J., 1931, 2532. 247 L. Pauling, 2. physikal. Chem., 1930, [B], 8, 326; A.,1930, 983. 248 P. Gunther and P. Rosbaud, ibid., p. 329; A., 1930,983; ibid.,1930, [B], 6, 459; A., 1930, 401. 249 0. Hassel and H. Kringstad, %.anorg. Chem., 1930, 191, 36; A., 1930, 1099.250 2. Krist., 1931, 76, 431; A., 789. 251 Physical Rev., 1931, [ii], 38,1040; A., 1218. 253 W. H.Zachariasen and H. E. Buckley, Physical Rev., 1931, [ii], 37, 1295; A., 896.254 W. H. Zachariasen and F. A. Barta, ibid., p. 1626; A., 1001. 2 5 5 P. Krieger,Amer. Min., 1930,15, 23; A., 1930, 1502. 256 B. Gossner and F. Mussgnug,Centr. Min., 1930, 321; Chem. Zentr., 1930, ii, 2362; A., 672. 257 A.Ferrariand C. CoIIa, AttiR. Accad. Lincei, 1929, [vi], 10, 594; A., 1930, 401. 258 J. M.Cork and S. L. Gerhard, Amer. Min., 1931, 16, 71. 259 Nature, 1931, 128,410; A., 1215.260 F. C. Kracek, J. Amer. Chem. SOC., 1931, 53, 1183,2609, 3339; A., 540,1115,1359. 261 D. A. Edwards, 2. Krist., 1931, 80, 154. 262 F. C. Kracak, J .Phy8ical Chem., 1930, 34, 225; A., 1930, 402. 263 A. P. Rostkovski, J . Russ.Phys. Chern. SOC., 1930, 62, 2067; A., 432. 264 2. Krist., 1929, 72, 230;1931, 78, 462; 79, 437; A., 1930, 1099; 1931, 1116, 1218. 265 C. A. Schus-terius, ibid., 1931, 76, 455; A., 548. 266 W. H. Zachariasen, ibid., 1930, 73,141; A., 1930, 1351. 267 Ibid., 1930, 75, 41; A., 414. 268 Ibid., p. 538;A., 549. 269 R. C. L. Mooney, Physical Rev., 1931, [ii], 37, 1306; A., 897.270 W.Biissem and K. Herrmann, 2. Krist., 1930, 74, 458; A., 414.271 J. H. Clouse, ibid., 1930, 76, 285; A., 414. 272 R. Brill, ibid., 1931, 77,506; A., 780. 273 J. Palacios and I. Navarro, Anal. Pis. Quim., 1931, 29,21 ; A., 414. 275 F. C. Kracekand C. J. Ksanda, J. Physical Chem., 1930, 34, 1741; A., 1930, 1099. 276 K.Herrmann and W. Ilge, 2. Krist., 1931, 80, 402. 277 M. Y . Colby, ibid., 1931,77, 49; A., 671. 278 A. Ogg, Phil. Mag., 1930, [vii], 9, 665; A., 1930, 671.279 M. Y. Colby, 2. Krist., 1931, 78, 168; A., 1218.2 8 l D. J .Bujor, ibid., 1931, 78, 1; A., 1218. 282 Ibid., 1930, 74, 306; Chem. Zentr.,1930, ii, 1658; A., 289. 283 Ibid., 1930, 75, 387; A., 550. 284 Ibid., p. 323;A., 550. 286 H. Seifert,ibid., 1931, 76, 455; A., 549.287 G. Menzer, Fortschr. Min., 1929, 13, 56;A., 1930, 140. 288 Idem, 2. Krist., 1930, 73, 113; A., 1930, 1351. 289 L.Pauling, ibid., 1930, 74, 104; A., 671.290 B. Gossner and F. Mussgnug, ibid., 1930, 72, 476; A,, 1930, 1352.29l P. L. Stedehouder and P. Terpstra, Physica, 1930,10, 113 ; A., 27. 292 M. L.Huggins and G. 0. Frank, Amer. Min., 1931, 16, 580. 293 W. H. Barnesand G. V. Helwig, Canad. J. Res., 1931, 4, 565; A., 1115. B. Gossnerand I?. Mussgnug, 2. Khst., 1930, 75, 410; A., 550. 285 M. Paid, Compt.rend., 1930, 191, 941, 1337; A . , 50, 169. 286 (Mme.) Mathieu, Mathieu, and262 J . Amer. Chem. SOL, 1931,53,2123; A., 897.274 B. Pesce, Gazzetta, 1930,60, 936; A., 289.280 W. H. Zachariasen and G. E. Ziegler, ibid., 1931, 80, 164.285 J.A. A. Ketelaar, ibid., 1931, 80, 190; A., 1359CRYSTALLOGRAPHY. 317Paid, ibid., 1931,192, 416; A., 444. 207 V . Kohlschutter and H. Nitschmann,2. physikal. Chem., Bodenstein Festband, 1931, 494; A., 1252. E.Onorato, 2. Krist., 1929, 71, 277; A., 1930, 672. 299 F. Halla, ibid., 1931,80, 349; A., 1359.801 L. Chrobak, Bull. Acad.Polonaise, 1929, [A], 361 ; A., 1930, 20. 302 Z. Herrmann, 2. anorg. Chem.,1930,187, 231; 1931,196, 79; 197, 212, 339; A., 1930, 528; 1931, 414, 671,789. 303 0. Hassel, 2. Krzkt., 1931, 79, 531; A., 1215. 304 L. Pauling,ibid., 1930, 72, 482; A., 151. 305 F . Halla and E. Mehl, 2. anorg. Chem.,1931, 199, 379; A., 1115. 306 W. Hofmann, Z. Krist., 1930, 75, 158; 1931,78, 279; A., 415, 1001. 307 C.Gottfried and J. G. Nagelschrnidt, ibid., 1930,73, 357; A., 27. 308 A. Ferrari and C. Colla, Atti R. Accad. Lincei, 1930,[vi], 11, 755; A., 1930, 1388. 3n8 W. F. de Jong, Physica, 1930, 10, 101;A., 1930, 1351.310 M. Prasad and H. M. Mapara, Indian J . Physics, 1931, 6, 41; A., 1002.311 K. J. Kabraji, ibid., pp. 81, 115; A., 1218. 312 W. Theilacker, Z. K k s t . ,1931, 76, 303; A., 550. 313 R. Corey and R. W. G. Wyckoff, Radiology, 1930,15, 241. 314 G. F. Huttig et al., 2. anorg. Chem., 1930, 189, 183, 190; 1931,196, 177, 403; A., 1930, 700; 1931, 432, 567. 315 E. Klever, Trans. Ceram.SOC., 1930, 29, 149; A., 1930, 1375. 816 H. P. Rooksby, ibid., 1929, 28,399; A., 1929, 1407. 317 G. F. Huttig and C. Kostelitz, G. F. Huttig andR. Kassler, 2.anorg. Chem., 1930, 187, 1, 16, 24; A., 1930, 543. V.Ipatiev, Ber., 1930,03, [B], 2365; A., 1930, 1387. 318 W. F. de Jong, Natuur-wetensch. T i j b . , 1930, 12, 69; A., 1930, 984.320 A. Ferrari and A. Scherillo, 2. Krist., 1931, 78, 496; A., 1116. 321 H.Wagner, Kolloid-Z., 1931, 54, 310; A., 564. 322 P. A. Thiessen and R.Koppen, 2. anorg. Chem., 1931, 200, 18; A., 1255. 323 G. F. Huttig and A.Konig, ibid., 1930, 193, 81, 93, 200; A., 1930, 1538. 324 W. Biltz and A.Lemke (with K. Meisel); W. Biltz and A. Sapper, ibid., 1930,186, 373, 387;A., 1930,390. 326 S.Holgersson and A. Serres, ibid., 1930,191, 35; A., 1930, 1355. 327 E. Rinne,Jahrb. Min., 1928, 58, 43; Chem. Zentr., 1929, i, 1556; A., 1930, 1137.32B Phil. Mag., 1931, [vii], 12, 1089.330 J .Wash. Acad. Sci., 1931, 21, 255; A., 1001. 331 F. Buschendorf, 2.physikal. Chem., 1931, [B], 14, 297; A., 1359. 332 H . S. Roberts and H. E.Merwin, Amer. J . Sci., 1931, [v]. 21, 145; A., 310. 333 E . Posnjak, ibid.,1930, [v], 19, 67; A., 1930, 279. 334 S. Holgersson, 2. anorg. Chem., 1930,192, 123; A., 1930, 1352. 335 K. Prcsserini, Gazzetta, 1930, 60, 389; A.,1930, 1007. 336 Idem, ibid., p. 957; A., 289. S. Holgersson and A.Herrlin, 2. anorg. Chem., 1931, 198, 69; A., 897. 338 Nach. Ges. Wiss.Gcittingen, 1931, 184. 338 N. W. Taylor, Z. physikal. Chem., 1930, [B], 9, 241 ;A., 1930, 1241.34l 2. Krist., 1930, 75,88; Chem. Zentr., 1930, ii, 2757; A., 415. 342 2. Kriat., 1930, 73, 97; Chem.Zentr., 1930, i, 2230; A., 1930, 1351. 343 B.Pesce, Gazzetta, 1931, 61, 107;A., 584. 344 2. Krist., 1931, 76, 289; A., 549. 345 Ibid., 1931, 77, 255; A.,789. 347 T. Thor-valdson, N. S. Grace, and V. A. I'igfusson, Canad. J . Res., 1929, 1, 201; A.,1930, 162. 348 B. Gossner, Z. Kriat., 1930, 75, 365; A., 671 ; M. G. Friedel,ibid., 1930, 73, 147; R. Hocart, ibid., 74, 20. 349 Jahrb. Min., 1930, [A], 61,1 ; A., 289.35O W. Feitknecht, Helv. Chim. Actot, 1930, 13, 22; A., 1930, 436. 361 H.IKenzel and A. Bruckner, 2. Elektrochem., 1930, 36, 63; A., 1930, 435. 352 B.300 P. Schonefeld, ibid., 1931,78, 16; A., 1218.325 €1. Forestier, C'ompt. rend., 1931, 192, 842; A., 671.329 2. K&t., 1931, 80, 416.340 L. Passerini, Gazzetta, 1930, 60, 754; -4., 151.s46 F. A. Steele and W. P. Devey, ibid., 1930, 73, 17318 BERNAL AND WOOSTER:Gossner and T.Biiuerlein, Ber., 1930, 63, [B], 2151 ; A., 1930, 1386. 353 B.Gossner and M. Arm, 8. Krist., 1929, 72, 202; Chem. Zentr., 1930, i, 2514;A., 1930, 1352. 35* G. Tunell and E. Posnjak, J. Physical Chem., 1931, 35,929; A., 800. 355 G. Aminoff (with R. Blix), I<. SvensEu Vetenskaps Alead.Handl., 1931, iii, 9, No. 6, 52; A., 1028. 356 8. Kpist., 1930, 73, 159; Chem.Zentr., 1930, i, 2713; A., 1930, 1352. 3 5 7 Ibid., 1931, 76, 322; A., 549.358 F. Machatschki, ibicl., 1930, 73, 123; Chem. Zentr., 1930, i, 2713; A.,1930, 1352.360 2. Krist., 1930, 74, 237; A., 289; Nature, 1931, 128, 210, 248; A.,1115; J. SOC. Glass Tech., 1930, 14, 295; A., 789. 361 S. von NBray-Szab6,Z. physikal. Chem., 1930, [B], 9, 356; A., 1930, 1241.362 2. Km'st., 1931,76, 454; 78, 136; A., 550, 1218. 363 Ibid., 1930, 73, 7 ; A., 1930, 1351.364 G. Aminoff, K . Svenska Vetenskaps Akad. Handl., 1931, [iii], 9, NO. 5, 14;A., 1002. 3G5 J. S. Hey and W. H. Taylor, 8. Krist., 1931,80,428. 366 W. H.Zachariasen, ibid., 1930, 73, 1; A., 1930, 1351. 367 B. E. Warren, ibid.,1930, 74, 131; A., 289. 3613 B. E. Warren and 0. R. Trautz, ibid., 1930, 75,525; A., 550.371 F.Machatschki, ibid., 1929, 70, 211; 1929, 71, 45; 1931, 76, 475; A., 550, 595.372 W. Kunitz, Chem. Erde, 1930, 4, 549; A., 1930, 1016. 373 Z. Krist., 1930,74, 139; A., 289. s74 B. Gossner and F. Mussgnug, Centr. Min., 1930, [A],81; A., 289. 3 7 5 Idem, ibid., 1929, [A], 175; A., 1930, 140. 376 3.3. E.Warrep and J.Biscoe, Z. Krist., 1931, 80, 391. 377 B. E. Warren and D. I.Modell, ibid., 1930, '75, 1 ; A., 415. 378 B. Gossner and F. Mussgnug, ibid.,1929, 70, 234; A., 595. 379 B. E. Warren, ibid., 1930, 72, 42, 493; A., 1930,844, 1352.380 B. E. Warren and D. I. Modell, ibid., 1930, 75, 161; A., 1931, 550.381 B. Gossner and F. Spielberger, ibid., 1929,72, 111 ; A., 1930, 1352. 382 G.Greenwood and A. L. Parsons, Univ. Toronto Studies Geology, 1931, 30, 29.3s3 H. Johansson, 2. Krist., 1930, 73, 31 ; A., 1930, 1343. 384 B. E. Warrenand W. L. Bragg, ibid., 1930, 76, 201; A., 415. 385 Proc. N a t . Acad. Sci.,1930, 16, 123; A., 1930, 732. 386 Z. Krist., 1930, 76, 211 ; A., 415. s87 L.Pauling, Proc. N u t . Acad. Sci., 1930, 16, 578; A., 1930, 1396.388 C. S.Ross and P. F. Kerr, J . Amer. Ceram. SOC., 1930, 13, 151; A., 1930, 569.389 E. T. Wherry, C. S. ROSS, and P. F. Kerr, Coll. S y m p . Ann., 1929, 7, 191 ;A., 1930, 1267.391 K.Yamamoto, J . Xoc. Chenz. I n d . Japan, 1931,34,244; A., 1029,1266. 392 W. H.Taylor and S. von NAray-Szab6,Z. Krist., 1931,77, 146; A., 671. 393 W. L.Bragg, ibid., 1930, 72, 518; Chem. Zentr., 1930, i, 1917; A , , 1930, 1351.394 B. Gossner and F. Mussgnug, ibid., 1931, 76, 525. 395 Idem, aid., 1929,70, 171; A., 1930, 140. 396 D. J. Bujor, ibid., 1931, 78, 386; A., 1116.3g7 F. Machatschki, Centr. Min., 1930, [A], 89, 154; A., 289. 398 B. Gossnerand F. Mussgnug, ibid., [A], 369; A., 415. 399 C. Dunbar and F. Machatschki,2. Krist., 1930, 76, 133; A., 415.400 Fortschr.Min., 1929, 14, 62; A., 1930, 1352; Juhrb. Min., Bei1.-Bd.,1931, 64, [A], Reinhart Brauns Festband, p. 251. 401 W. Eitel and G.Tromel, Portschr. Min., 1929, 14, 28; A., 1930, 1352; Naturwiss., 1930, 18,469; A., 1930, 1241. 402 G. Tromel, 2. Krist., 1930, 73, 64. 403 E. Schie-bold, Naturwiss., 1930, 18, 705; A., 1930, 1099. 404 F. A. Bannister, Min.Mag., 1931, 22, 569. 405 B. Gossner and F. Mussgnug, 8. Krist., 1930, 73,187; A., 1930, 1352. 406 H. Hartwig, Naturwiss., 1930, 18, 601; A., 1930,984; 2. Krist., 1931, 78, 173; A., 1030. 40' W. H. Taylor, a i d . , 1930, 74,359 G. Menzer, ibid., 1930, 75, 265.3F9 W. H. Zachariasen, ibid., 1930, 74, 226.3'0 B. E. Warren and D. I. Modell, ibid., 1931, 78, 422; A., 1116.390 F. Kastner and F.K. Mayer, Chem. Erde, 1931,6, 269; A., 595CRYSTALLOQRBPHY. 3191 ; A., 550. 408 F. Klistner, ibid., 1931, 77, 353; A., 789. 409 F. A. Ban-nister, Min. Mag., 1931, 22, 469; A., 595.411 L.Pauling, Pmc. Nat. Acud. Sci., 1930, 16, 453; A., 1930, 1240. 412 Idem,Z. Krist., 1930, 74, 213 ; A., 289. 413 F. Halla and E. Mehl, ibid., 1930, 75,481; A., 1931, 550. 414 A. L. Parsons, Univ. Toronto Studies Geol., 1931,29, 27. 415 J. Wyart, Compt. rend., 1930, 190, 1564; A., 1930, 984. 416 B.Gossner and K. Briickl, Jahrb. Min., 1928, [A], 58, 349; A., 1930, 1100.417 B. Gossner and F. Mussgnug, 2. Krist., 1930, 73, 52; A., 1930, 1352.4l8 F. Zambonini and A. Ferrari, Atti R. Accad. Lincei, 1930, [Vi], 11, 782;A., 1930, 1397.421 H. June, Chem. Erde, 1931,6, 275; A., 1030.B. Gossner and F. Mussgnug, 2. Krist., 1931, 76, 525;A., 650. 423 E. N. Bunting, Bur. Stand. J.Res., 1930,5,325; A., 41. 424 G. W.Morey, F. C. Kracek, and N. L. Bowen, J . SOC. Glass Tech., 1931, 15, 57;A., 1011; 425 N. L. Bowen and E. Posnjak, Amer. J . Sci., 1931, 22, 193,203. 426 J. A. Hedvall and P. Sjoman, 2. Elektrochem., 1931, 37, 130; A.,582; Svensk Kem. Tidskr., 1930, 42, 40; A., 1930, 559. 427 P. Sjoman,TeEn. Samf. Handl., 1930, No. 7; A., 1010. 428 Ehrenberg, 2. physikal.C'hem. , 1931, 14, 421. 429 I. Weyer, Zement, 1931, 20, 48 ; A., 921.431 V. A. Vigfusson. Amer. J . Sci., 1931,[v], 21, 67; A., 310. 432 J. T. Randall, H. P. Rooksby, and B. S. Cooper,Z. Krist., '1930, 75, 196; A., 550; Nature, 1930, 125, 458; A., 1930, 526.433 J. T.Randall and N. Gee, J. SOC. Ulass Tech., 1931, 15, 41; A., 1004.435 J. de Smedt, W. H. Keesom, and H. H. Mooy, Proc. K. Akad. Wetensch.Amsterdam, 1930, 33, 255; A., 1930, 671. 436 W. H. Keesom and H. H.Mooy, Nature, 1930, 125, 889; A., 1930, 983; Proc. K . Akad. Wetensch.Amsterdam, 1930, 33, 447; A., 1930, 1099. P3' G. Natta and A. G. Nasini,Nature, 1930, 125, 889; A., 1930, 983; Atti R. Accad. Lincei, 1930, [vi], 8,141; A., 288. 438 Idem, Nature, 1930, 125, 457; A., 1930, 528. 439 W. H.Keesom, J. de Smedt, and H. H. Mooy, Pmc. K. Akad. Wetensch. Amsterdam,1930, 33, 814; A,, 150.440 G. Natta, Nature, 1930, 126, 96; 1931, 127, 235; A., 1930, 1099; 1931,414. 441 L. Vegard, Natumoiss., 1930, 18, 1098; Nature, 1930, 126, 916;2. Krist., 1931, 77, 23; A., 150, 671. 442 G. Natta, A t t i R. Accad. Lincei,1930, [vi], 11, 679, 749; A., 1930, 1350. 443 G. Natta and E. Casazza,Gazxetta, 1930, 60, 851; A., 150. 444 2. Physik, 1931, 68, 184; A., 548;1931,71,299; A., 1218. 445 Ibid., 1931,70,699; A., 1115. 446 L.Vegard,ibid.,1931,71,465; A., 1218. 447 Idem,Z.Krist., 1931,77, 411; A., 789. 448 H.H.Mooy, PTOC. K. Akad. Wetensch. Amsterdctm, 1931,34,550; Nature, 1931,127,707; A., 790. 449 Idem, Proc. K . Akad. Wetensch. Amsterdam, 1931, 34, 660;A., 1002.450 G. Natta, Gazzetta, 1930, 60, 911; A., 151. 451 0. Hassel and H.Kringstad, 2. physikal. Chem., 1931, [B], 13, 1; A., 897. 452 H. Hansen,ibid., 1930, [B], 8, 1; A., 1930, 981. 453 F. M. Jaeger, Chem. Weekblad, 1930,27, 50; A., 1930, 280. 454 M. A. Bredig, 2. Krist., 1930, 74, 49; A., 551.4 5 5 R. Brill, ibid., 1931, 77, 36; A., 671. 456 H. Moller, ibid., 1931, 76, 500;A., 549. 458 J. M. Adams, Proc. Roy. SOC., 1930,[A], 128, 588; A., 1930, 1099. 459 E. Brandenberger, 2. Kriet., 1930, 73,429; A., 288.461 Ibid., 1931,[B], 11, 455; 12, 377; A., 414, 788. 462 Compt. rend., 1931, 192, 559; A.,548. 463 G. Briegleb, 2. physikal. C'hem., 1929, 144, 321, 340; A., 1930, 22.410 B. Gossner and F. Mussgnug, 2. Krist., 1930, 74, 62; A., 289.419 J. Wyart, Compt. rend., 1931, 192, 1244; A., 789.420 M. G. Evans, J., 1931, 1556; A., 902.430 R. Brill, ibid., 1930, No. 34.449u M. L. Huggins and B. A. Noble, Amer. Min., 1931, 16, 519.457 Ibid., 1931, 80, 204.460 2. phy8ikal. Chem., 1930, [B], 10, 149; A., 1930, 1503320 BERNAL AND WOOSTER :464 G. Natta and L. Passerini, Nature, 1930,125, 707 ; A., 1930, 671. 465 A. V.Frost, J . Russ. Phys. Chem. Soc., 1930, 62, 2235; A., 671. 466 H. vonSteinwehr and A. Schulze, Z. Physik, 1930, 63, 815; A . , 1930, 1258. 468Chem. Reviews, 1930, No. 4. 469 T. Malkin, Nature, 1931, 127, 126; A., 290.470 Proc. Roy. SOC., 1930, [ A ] , 127, 417; A., 1930, 844. 471 Nature, 1930,126, 278; A., 1930, 1241. 472 G. L. Clark and H. A. Smith, Ind. Eng. Chem.,1931, 23, 697; A., 897. 473 2. physikal. Chem., 1931, [B], 15, 285; A., 1218.4 7 4 G. H. Graves, Ind. Eng. Chem., 1931,23, 762; A., 1002. 4 7 5 R. D. Bennett,J . Franklin Inst., 1931, 211, 481; A., 670. 4 7 6 C. Pawlowski, J . Chim.physique, 1930, 27, 266; A . , 1930, 1085. 477 F. Francis, S. H. Piper, and T.Malkin, Proc. Roy. SOC., 1930, [A], 128, 214; A., 1930, 1161. 478 Y. Tanaka,R. Kobayashi, and K. Shimizu, J . SOC. Chem. Ind. Japan, 1930, 33, 364;d., 1930, 1504. 479 Compt. rend., 1930, 190, 945; 191, 200; A., 1930, 740,1100.480 A. Joff6 and P. Lukirsky, J . Phys. Radium, 1930, [vii], 1, 406; A.,289. 4 8 1 R. Spychalski, Rocx. Chem., 1931, 11, 427; A . , 1008. 483 W. A.Caspari, J., 1929, 2709; A., 1930, 139. 483 J. Amer. Chem. SOC., 1930, 52,3739; A., 1930, 1350. 484 W. Eissner and R. Brill, Z. Krist., 1931, 79, 430;A., 1219. 4e5 R. W. G. Wyckoff, ibid., 1930, 74, 25; A., 551. 486 Ibid., p.29; A., 551. 4s7 Ibid., 1930, 76, 174; A., 415. 488 Ibid., 1930, 74, 301.489 Nature, 1930, 126, 167.490 Ibid., 1930, 75, 529; A., 550. 491 Ibid., 1931, 77, 424; A., 790. 492Ibid., 1931, 78, 363; A., 1002. 493 F. V. Lend, Naturwiss., 1931, 19, 19;A., 152. 4g4 E. Hertel, 2. physikal. Chem., 1930, [B], 11, 279; A., 289.495 (Sir) W. Pope and J. B. Whitworth, Proc. Roy. SOC., 1931, [ A ] , 136, 357.496 Z. Krist., 1929, 72, 301; A., 1930, 983. 497 0. L. Sponsler and W. H.Dore, J . Amer. Chem. SOC., 1931, 53, 1639; A., 790. 498 Nature, 1931, 127,11; A., 152. 499 T. C. Marwick, Proc. Roy. SOC., 1931, [A], 131, 621; A . ,897.501 Z. Krist., 1931,78, 477; A., 1116. 502 J., 1931, 2313; A., 1275. 503 J. Young and F. W.Spiers, 2, Krist., 1931, 78, 101; A., 1219. 504 2. Elektrochem., 1931, 37, 540;A., 1219. 505 Tidsskr. Kjemi Berg., 1930, 10, 128; A., 27. 506 Z. Krist.1931, 78, 76; 80, 1; A., 1219. 508 G. Bruni,and G. Natta, Atti R. Accad. Lincei, 1930, [vi], 11, 929, 1058; A., 152.509 Proc. Roy. SOC., 1931, [A], 133, 536.510 Ibid., 1931, [A], 131, 612; A . , 897. 511 M. A. Bredig and H. Moller,Z. Krist., 1929, 71, 331; A., 1930, 672. 512 2. physikal. C%em., 1831, [B],12, 139; A., 551. 513 E. Hertel, ibid., 1930, [B], 7, 188; A., 1930, 668.514 M. A. Bredig, 2. Krist., 1930, 74, 56; A., 672. 515 H. P. mug, E. Mack,jun., and F. C. Blake, J . Amer. Chem. SOC., 1929, 51, 2880; A., 1929, 1368.516 J. M. Robertson, Proc. Roy. SOC., 1929, [A], 125, 542; A., 1929, 1367.517 Nature, 1930, 125, 456; A., 1930, 528. 518 Ibid., p. 456; A., 1930, 528.519 E. Hertel and G. H. Romer, 2. physikal. C l h P m . , 1930, [BJ, 11, 90; A.,152.521 E.Hertel and G. I-. Romer, 2. Krist., 1931, 76, 467; A . , 660. 522 G. L. Clarkand L. W. Pickett, Proc. Nut. Acad. Sci., 1930, 16, 20; A., 1930, 528; J.Amer. Chem. SOC., 1931, 53, 167; A., 290. 523 H. Thiele, Kolloid-Z., 1931,56, 129; A., 1124; 2. anorg. Chem., 1930,190, 145; A., 1930, 872. 624 Ber.,1930, 63, [B], 1248; A., 1930, 875; Z. Elektrochem., 1931, 37, 613. tit5 G.Greenwood, Arner. Min., 1931, 16, 473. 526 E. Hertcl and H. Kleu, 2.physikal. Chem., 1930, [B], 11, 59; A., 153. 537 E. Hertel and G. H. Riimer500 G. W. McCrea, Nature, 1931, 127, 162; A., 290.507 Ibid., 1931, 80, 5; A., 1219.520 M. Prasad, PhiE. Mag., 1930, [vii], 10, 306; A., 1930, 1241CRYSTALLOGRAPHY. 321ibid., p. 7 7 ; A., 153. 528 E. Hertel, ibid., Bodenstein Festband, 1931, 267;A., 1219. 52g E. Hertel and K. Schneider, ibid., 1931, [B], 12, 109; A . , 415.530 Idem, ibid., 1931, [B], 13,387; A., 1114; 2. Elektrochem., 1931,37, 536;A., 1218. 531 A. Ferrari and A. Scherillo, 2. Krist., 1931, 80, 45; A., 1219.532 T. C. Marwick, Nature, 1930, 126, 438; A., 1930, 1353. 533 2. Krist.,1930, 74, 202. 534 A. Burgeni, F. Halla, and 0. Kratky, ibid., 1929, '41, 263;A., 1930, 844.J. D. BERNAL.W. A. WOOSTER.REP.-VOL. XXMII.

ISSN:0365-6217    

DOI:10.1039/AR9312800262

出版商:RSC    

年代:1931

数据来源: RSC

摘要:

COLLOID CHEMISTRY.I WAS entrusted by the Council to arrange for the preparation of aReport on Colloid Chemistry. The last Report (1923) consistedlargely of a general summary of the whole subject. Since it hasbeen found by experience that in such special fields a Reportreviewing some selected topics of importance is of more generalutility than one covering the whole range of subjects, 41 have askedDr. W. T. Astbury, Mr. D. C. Henry, and Dr. R. K. Schofield toprepare monographs on branches of colloid chemistry with whichthey are particularly well acquainted.E. I<. RIDEAL.PART I.-THE STRUCTURE OF FIBRES.By W. T. ASTBURY.The very considerable advances in our knowledge of the structureof fibres that have been made during the last five years or so are duealmost entirely to the interpretation of their X-ray diffractionphotographs in the light of developments in the chemistry of com-pounds of high molecular weight.For a number of years previouslyit had been known that vegetable and animal fibres give rise tocharacteristic X-ray photographs-now generally described as'' X-ray fibre photographs "-but for reasons which appear below,these photographs were of too indeterminate a nature to be analysedsuccessfully without the help of more decisive chemical inform-ation than was at the time available. The deduction, by Haworth,Freudenberg, and others,2 of the structural formula of cellulose as along chain of hexagonal ring systems proved sufficient, however, tosupply the chemical impulse required, and from that time onwardsthe subject has developed so rapidly, the X-ray and chemical resultsmutually reinforcing one another, that it is now possible to form acomprehensive picture of the whole field of fibre structure and refereach individual case to comparatively simple common principles.P.Schemer, Nach. Ges. Wiss. Gdttingen, 1918, 98; R. 0. Herzog andW. Jancke, 2. Physik, 1920,3,196 ; R. 0. Herzog, W. Jancke, and M. Polanyi,ibid., p. 343; M. Polanyi, Naturwiss., 1921, 9, 337; 0. L. Sponsler, J. Gen.Physiol., 1925-26, 9, 221, 677; 0. L. Sponsler and W. H. Dore, ColloidSymposium Monograph, 1926, 4, 174; 0. L. Sponsler, Nature, 1927, 120, 767;1930, 125, 633 ; Naturwiss., 1928, 16, 263.2 W. N. Haworth, " The Constitution of Sugars,'' London, 1929PLATE I.FIG.~.-RAMIE.FIG. 3.-sTRETCHED RUBBER.FIG. Z.-uNSTRETClIE:U RUBBER.FIG. 4.-NATURAL SILK.[To face puge 322PLATE 11.FIG. ~.-u-KERATIN. FIG. KERATIN.FIG. 7.-FEATHER KERATINCOLLOID CHEMISTRY. 323A very thorough and valuable account of the structure of compoundsof high molecular weight, in both their chemical and their crystallo-graphic aspects, was given by K. H. Meyer and K. Mark in 193OY3and more recently the scheme has been completed by the inclusionof the elastic protein fibres such as hair.4Genera 1 Character is t ics .A typical X-ray fibre photograph, obtained simply by sending afine beam of X-rays perpendicularly through a bundle, about 1 mm.thick, of parallel fibres, is that of ramie (Plate I, Pig. 1).Thissubstance gives one of the best-defined fibre photographs known,in the sense that it simulates closely the ideal “rotation photo-graph ” of a single visible crystal; but it has, in common with themore indeterminate photographs of silk, hair, etc., certain featureswhich we have learnt always to associate with the structure ofnatural fibres. In the first place, the ideal fibre photograph isgeometrically equivalent to the single crystal rotation photograph,that is, the photograph given by a single crystal rotating about anaxis perpendicular to the X-ray beam. It follows from this thatfibres are in general composed, either wholly or partly, of a multitudeof crystals, or pseudo-crystals, so lying in the body of the fibre as tohave always one and the same crystallographic axis approximatelyparallel to the length of the fibre, while all crystallographic directionsperpendicular to this preferred axis are in random orientation.* Inthe second place, the crystalline particles of the fibre substance,whose existence is thus demonstrated by X-ray reflexion eventhough their dimensions are submicroscopic, must be considerablylonger than they are thick, because the X-ray reflexions, or “ spots,”lying on or near the equator of the typical fibre photograph arealways broader and more diffuse than those lying on ’or near themeridian of the photograph.This is a consequence of the diffractionprinciple, according to which the resolving power decreases with thenumber of diffracting centres. The fibre crystals are therefore longenough in a direction parallel t,o the fibre axis to contain sufficientdiffracting centres to give rise, on the meridian, to comparativelysharp spots (which are X-ray reflexions, from planes perpendicularto the fibre length), but so thin perpendicular to the fibre axis thatthe crystal planes parallel to this axis reflect only broad, diffuse3 “ Der Aufbau der hochpolymeren organischen Naturstoffe,” Leipzig, 1930.4 W.T. Astbury, “The Molecular Structure of Natural Fibres.” (Alecture published by Metropolitan-Vickers Electrical Co., Manchester, 1931.)* Such an effect could arise, of course, simply from the fact of using a bundleof fibres for the X-ray photograph, but the present evidence is that there isno selective orientation perpendicular to the fibre, even in single fibres (seelater)324 ASTBURY :X-ray beams.In general, we may say that the crystallites have anaverage thickness of no more than 100 A.U., and an average lengthperhaps ten times as great (see below).It is natural to identify these long, thin crystallites revealed byX-rays with the " micelles " postulated long ago by C. Nageli andinvestigated in detail more recently with the aid of polarised light,Gsince water adsorption in cellulose, silk, wool, etc., produces apercentage lateral swelling which is some 15 times greater than thelongitudinal swelling without a corresponding change occurring inthe X-ray photographs. The water is therefore in the main adsorbedon the surface of the crystallites or micelles.It does not follow, ofcourse, that we are justified in ascribing sharp boundaries to thecrystallites : the observed X-ray and swelling effects could quitewell arise from ill-defined aggregates of widely varying thickness.The combination of numerous X-ray observations with the mostrecent concepts in the chemistry of compounds of high molecularweight leads to the conclusion that the elongated, submicroscopiccrystallites which are the basis of fibre structure are in reality noother than bundles, of various thicknesses and of varying degrees ofperfection, of long-chain molecules which are in general linearpolymerides of relatively simple chemical units. For instance,cellulose molecules being long chains of @-glucose residues linked byprimary valencies-what are known in German literature as " Haupt -valenzketten "-it is clear that such chains can be grouped togetherby the operation of ordinary crystallographic forces to form bundles,long and of well-defined periodicity parallel to the fibre axis, but thinand possibly of ill-defined periodicity perpendicular to the fibre axis.Reversible Transformations in Fibre Xtructure.The X-ray photographs of natural silk (fibroin), and of the variouscellulose fibres, both natural and artificial, exhibit no fundamentalchange when the fibres are stretched even to the breaking point.I nthose cases where there is a lack of strict alinement of the crystallites,the alinement is improved by stretching, as might be expected ; butthe essential features of the photographs remain unchanged. Onthe other hand, the photograph of animal hairs (keratin) undergoes,a t extensions exceeding about 25%, a transformation into another,and different, fibre photograph, which is replaced once more by thenormal photograph when the fibres are returned t o their originallength.' The two X-ray photographs of hair are thus a physical'' Die Micellartheorie " (Ostwald's Klassiker der exakten Wissensehaften,Nr.227, Leipzig, 1928) ; H. Mark, Naturwiss., 1928, 16, 892.A. Frey, Jahrb. wiss. Bot., 1925-26, 65, 195; A. Frey-Wyssling, 2. zuiss.Mikr., 1930, 47, 1.W. T. Astbury, J . SOC. Chem. Ind., 1930, 49,441; J. Text. Sci., 1931, 4, 1COLLOID CHEMXSTRY. 325record of a reversible intramolecular transformation involvingchange of length.That rubber undergoes an intramoleculartransformation on stretching was discovered by J. R. Katz,s but inthis case the change is from an amorphous state (unstretched) to acrystalline state (stretched). Except for this difference, that theX-ray photograph of normal rubber (Plate I, Fig. 2) is an“ amorphous photograph ” and that of stretched rubber (Plate I,Fig. 3) a true fibre photograph, while the photographs of bothnormal and stretched hair art: fibre photographs, the two reversiblechanges appear to be quite analogous, and due to the unfolding ofcoiled molecular chains which tend to return to their original foldedstate when the tension is removed. It seems clear that the molecularchains of rubber are polyrnerised isoprene, while those of keratinare apparently polypeptides.The General Theory of Fibre Structure.The special features of natural fibres revealed by X-ray analysisand described briefly above suffice to give a rational explanation oftheir general properties in comparatively simple It hasalready been mentioned how the well-known swelling and opticalphenomena follow, but perhaps the most striking conclusions relateto their characteristic elastic properties.Natural silk and thecellulose fibres exhibit only a little true elasticity, since Hooke’s lawfails a t extensions of 1 or 2yo, and there is only a partial recoveryfrom higher extensions. (This partial recovery is the so-called“ Nachwirkung,” and is probably due to irregularities among themicelles and on their surfaces.) If now the molecular chains whichare the basis of fibroin and cellulose are already extended as far asis stereochemically permissible, fibres built from them in the waydescribed will stretch only in virtue of internal slipping between thechain bundles, and complete recovery from extension beyond theHooke’s law limit will be impossible.This argument is in fullagreement with the findings of X-ray analysis, which show (1) thatthe repetition of chemical pattern along the fibre axis correspondsclosely with what we should expect from extended polypeptide andcellulose chains, respectively (see Fig. 2 and Fig. la); and (2) thatthe chain bundles are preserved more or less int’act during extension.It seems probable that the fibres break finally through a completeseparation of micelles a t the point of rupture, for l\llleyer and Markhave shown that the work required to break a cellulose fibre is lessthan what would be required to break the primary valency bonds inthe molecular chains.Nevertheless, owing to the great length ofthese chains and the additivity of intermolecular forces along their8 Chem.-Ztg., 1925, 49, 353; Naturwis$., 1925, 13, 411326 ASTBURY :HO*FH /"\ (I'HOCH CH-CH,*OH/"\CH,*CO-NH*(iH pHO*CH CH*CN,*OHPH\ Celliilose chain. PH\ Chitin chain.F I G . 2.Rl I/Co\~H/CH\Co/:\CH/co\~H/ II i l~f- 3.5 B. -+>I ' R2This line of reasoning obviously fails-or, a t least, is incomplete-in the case of animal hairs, simply because the photograph ofunstretched hair does not agree with what we should expect fromextended peptide chains such as we must conclude are present innatural silk.Similarly, the photograph of unstretched rubber isalso anomalous, for it is only an " amorphous " photograph contain-ing no information at all as to periodicities in the chains of poly-merised isoprene. But the X-ray analyses of both stretched hair andstretched rubber are in good accord with previous chemical con-siderations, for we find that the photograph of stretched hair isanalogous to that of unstretched silkyg while that of stretched rubbercan be explained on the basis of long molecular chains with periodicitycorresponding to isoprene units linked in the cis-configuration.109 W.T. Astbury and A. Street, Phil. Trans., 1931, [ A ] , 230, 75; W. T.Astbury and H. J. Woods, Nature, 1930,126, 913.10 K. H. Meyer and H. Mark, Ber., 1928, 61, 1939; H. Fikentscher andH. Mark, Kolloid-Z., 1929, 49, 135327 COLLOID CHEMISTRY.Stretched hair, then, is built of fully extended peptide chains likethose in natural silk (whether stretched or unstretched), andstretched rubber is built of extended isoprene chains which formcrystallites on alinement. Both substances, when the tension isreleased, may be caused to recover their original length-in the caseof hair, through the action of water, etc.,ll and in the case of rubberthrough the action of heat l2-whereupon the original (abnormal)photographs reappear. The remarkable long-range elasticity ofhair and rubber-hair may be stretched to twice: and rubber to tentimes its original length 13-is thus, in each case, to be ascribedsimply to an intramolecular change which may be brought aboutby tension, and is accompanied by unfolding of molecular chains andconsequent considerable elongation.As would be expected, theload-extension curves of hair and rubber are closely analogous,4just as are those of viscose and natural silk.4The main fundamental properties of natural fibres may thereforebe explained in terms of the following three generalisations :(1) Fibres are built of long, thin, sub-microscopic crystallites ormicelles, which are bundles, of various sizes and of various degreesof perfection, of molecular chains of relatively simple chemical unitslinked before and behind by primary valencies.In ca,ses such assilk, ramie, hair, wool, etc., the crystallites lie with their long axesroughly parallel to the fibre axis ; in other cases, such as cotton, theyare inclined a t a constant angle to the fibre axis.14 The opticalproperties, adsorption phenomena,15 and the general physico-chemical behaviour3 of fibres are the consequences of this sub-crystalline or micellar structure.(2) Fibres may consist of extended molecular chains, e.g., cellulose,natural silk, stretched rubber, stretched hair, or of folded molecularchains, e.g., unstretched rubber and unstretched hair.(3) The extended molecular chains being incapable of furtherextension, fibres composed of such chains extend by internal slippingfrom which they cannot recover their original length : but foldedchains may unfold and pass into the extended state, thus giving riseto long-range elasticity. An intermediate form of extensionphenomenon is that due to alinement of chains or micelles : themaximum possible extension by this mechanism is 57%.1611 S.Shorter, J . Text. Inst., 1824, 15, 2 0 7 ~ ; J . Soc. Dyers Col., 1925, 41,212; J. B. Speakman, J . Text. Inat., 1926,17,457~; 1927,18,431~.la L. Hock, Kolloid-Z., 1925, 35, 40.13 H. Mark and G. von Susich, ibid., 1928,46, 11 ; A., 1928, 1186.14 R. 0. Herzog and W. Jancke, Z. physikal. Chem., 1928, [A], 139, 235.1 5 J. B. Speakman, J. SOC. Chem. Id., 1930,49,209~.16 H. J. Poole, Trans.Paraday soc., 1925, 21, 114; A., 1925, ii, 519; W.T. Astbury and A. Street, Phil. Trans., 1931, A, 230, 75328 ASTBURY :Cellulose and its Derivatives.During the last few years a considerable amount of informationhas been acquired, chiefly by X-ray analytical methods, concerningthe detailed molecular structure of the two forms of cellulose, nativecellulose and mercerised cellulose (" Hydratcellulose "), and ofsixteen of their derivatives. It is impossible here to go into theseresults with any thoroughness, but K. Hess and C. Trogus l7 havecompiled a valuable summary in which it is shown how the twocelluloses and ten of their derivatives appear to be based on aperiodicity along the fibre axis of 2 x 5-15 A.U., while of the remain-ing six derivatives, in order to interpret their X-ray photographs,it seems necessary to assume for four of them 3 x 5.15x.U., foranother 4 x 5.15 A.U., and for still another (trinitrocellulose)5 x 5.15 A.U.It is concluded from these data that the dimension,5.15 A.U., which is the length of a glucose residue, stands in a closerrelation to the constitution of cellulose than does the dimension,10-3 A.U., the length of a cellobiose residue (see Fig. la) ; that isto say, that the cellobiose residue does not pre-exist in the cellulosemolecule, as has been suggested by Haworth.2 It is true that theseanomalous fibre periodicities are a t the moment a source of somedisquiet with regard to the true nature of the cellulose chain, but inview of the fact that many existing fibre photographs defy unambiguousevaluation, there does not yet appear to be sufficient reason toaccept the conclusions of Hess and Trogus as final.The cellulosechain may be based fundamentally on a repetition of the cellobioseresidue, but it does not follow from this that the periodicity of thechain should remain a constant multiple of 5-15 A.U. for each andevery possible type of addition or substitution reaction along itssides. Moreover, it is only in the case of native cellulose l8 and ofmercerised cellulose l9 that we can feel any certainty about thetrue size of the unit of pattern.The atomic arrangement in the two celluloses has now beeninyestigated in some detail ; but it will suffice here to state that theybear a very simple relation to each other based on a small rotationof the molecular chains about their long axes.20 It would appearthat mercerised cellulose is the stable form, since it is always pro-duced from the native fibre when the latter has been sufficiently1 7 2.physikal. Chem., Bodenstein Festband, 1931, 385.18 H. Mark and K. H. Meyer, ibid., 1929, [B], 2, 115; R. K. Andress, ibid.,p. 380; 0. L. Sponsler, Nature, 1930, 125, 633; Protoplasma, 1931, 12, 241;R. 0. Herzog and W. Jancke, 2. physikal. Chem., 1928, [A], 139, 235.19 R. K. Andress, ibid., 1929, [B], 4, 190; A. Burgeni and 0. Kratky, ibid.,p. 401 ; K. Weissenberg, Naturwiss., 1929,17, 181.2o W. T. Astbury and T. C. Marwick, Nature, 1931, 127, 12COLLOID CHEMISTRY. 329swollen to separate the chains, and the swelling agent afterwardsremoved.Much of our knowledge of the structure of the cellulosederivatives is due to a long series of investigations by Hess andTrogus.21 As would be expected, the side spacings of the crystallitesformed in these derivatives vary in a manner depending on the natureof the groups substituted down the sides of the original cellulosechains, while, as mentioned above, in the majority of cases investig-ated the fibre period remains unaltered (10.3 A.U.). The chitinchain, an acetylglucosaminc? chain, is shown diagrammatically inFig. l b . I t s fibre periodicity has been determined by H. W. Gone11 22as 10.4 A.U.Natural Silk.The original results of R. Bri11,23 who obtained good fibre photo-graphs of several varieties of natural silk (Plate I, Fig.4), are mostsatisfactorily explained by the suggestion of K. H. Meyer and H.Mark that the fibroin crystallites or micelles are built of extendedpolypeptide chains consisting for the most part of glycine andalanine residues. The unit of pattern repeats itself along the fibreaxis at an interval of almost, exactly 2 x 3.5 B.U. (see Fig. 2), andthe side spacings of the X-ray photographs are also in good agree-ment with what would be expected from parallel chains of amino-acidresidues. More recently, 0. Kratky 25 has used, instead of naturalfibres, the actual secretion in the spinning gland of the silk-worm.By ‘‘ cold-working ” this secretion by stretching and rolling, he hasobtained thin films 1-2 m.long and 2-3 mm. wide in which thereis a higher degree of crystallite orientation than is found in the fibres(see above). The X-ray photographs of such specimens throwfurther light on the true dimensions of the unit of pattern of fibroin,so that whichever is correct of the possible unit cells put forward, itseems clear that the separation of the parallel polypeptide chainslies somewhere between 4.5 and 6.1 B.U.The above remarks refer to the familiar diffraction diagram givenby the silk of Bombyx mori. The same author has shown, however,that a different X-ray pattern is given by the silk of Thelea poly-phemus, Satonia, Pavonia, and Jamamai. In these cases the fibreperiod appears to be 7.2 & 0-25 B.U. (instead of 6.95 3 0-25 A.U.for Bombyx mori), but it is not certain, on account of difficulties ofmeasurement, whether this particular deviation is a real one, though21 K.Hess and others, Ber., 1928,61, 1982 ; 2. physikal. Chem., [B], 4-9.22 2. Physik, 1924,25,118; K. H. Meyer and H . Mark, Ber., 1928,61, 1936 ;A., 1924, ii, 588 ; 1928, 1228.2s Annalen, 1923, 434, 204.25 2. physikal. Chem., 1929, [BJ, 5, 297; 0. Kratky and S . Kuriyama, ibid.,24 Bey., 1928, 61, 1932.1931, [ B ] , 11, 363.L 330 ASTBURY :there is no doubt as to the general difference of the fibre pattern ofthe silk of Satonia from that of Bombyx mori.Animal Hairs, etc.It appears to be now definitely established that animal hairs,together with nails, horn, spines, whale-bone, etc., are built funda-mentally from one and the same protein, a-keratin, so named todistinguish it from the extended form of the same protein, p-keratin,which is developed by stretching the natural fibres.4$ '9 I n orderto account quantitatively for the observed maximum extension,approximately 100 yo, and the dimensional characteristics of theX-ray photographs of the unstretched and the stretched form,respectively (Plate 11, Figs.5 and 6), the following intramoleculartransformation has been put forward :\The details of such a reversible change, that is to say, the correctorientations of the linked units of the main chain and the precisenature of the side chains involved, have yet to be worked out; butthe skeleton framework postulated has proved remarkably success-ful in explaining the basic properties of hair structure.Further-more, it has thrown light on the properties of proteins in general,inasmuch as it has shown how, by suitable folding of a normalprotein chain, ring systems may be formed which are of the natureof diketopiperazine rings,2s and resistance to chemical attackenhanced by the internal saturation of residual valencies (see below).2o N. Troensegaard, 2. physiol. Chem., 1923, 127, 137COLLOID CHEBEISTRY. 331A striking example of this phenomenon is a.fforded by the action ofsteam on animal hairs. It is a well-known fact that stretched hairloses its power of recovery when exposed to steam and becomes“ set ” in the elongated form (“ permanent set ” of wool, “ permanentwave ” of human hair).X-Ray analysis shows that this is due to asusceptibility of the extended protein chain (p-keratin) to the attackof steam which is absent in the folded chain (a-keratin). That hairwhich has been steamed while stretched can no more return to thea-form is shown conclusively by the “ fixing ” of the p-photograph.too, that the normal form ofanimal hairs which gives rise to the X-ray photograph of a-keratinis not in a state of maximum contraction, since it is possible tocontract it still to half its original length ! Thus the keratin chainof hair has in reality an extensibility of some 300~o-from - 50%to + 100%-and so compares favourably with such an enormouslyelastic substance as india-rubber.Another X-ray observation in the field of the molecular structureof fibrous epidermal proteins is of peculiar interest for palaeontologyand evolutionary theory.Hitherto it has been usual to classifyfeathers and scales with animal hairs, etc., under the heading ofkeratin. An X-ray photograph (Plate 11, Fig. 7) shows that thisclassification is incorrect ; that, in fact, the molecular structure of agoose quill, for instance, is quite different from that of the proteinwhich has been described above as a-keratin. The same X-raydiffraction pattern as is given by feathers is given also by tortoise-shell, so that the affinity between reptiles and birds and theirdifferentiation from the ma,mmals have now been demonstrateddirectly by the methods of molecularIt has now been dernon~trated,~,Micelle Xixe.A classical paper due to M.von Laue 28 gives the general theory ofthe determination of the dimensions of minute crystals by means ofthe diffraction of X-rays, the possibility of which was first shownby P. As mentioned above, the method dependsessentially on the relation between the resolving power of the crystallattice and the total number of diffracting centres in the lattice.Thus by measuring the broadness of each X-ray reflexion we can,after making allowance for the dimensions of the specimen underexamination, etc. ,30 estimate t’he average thickness of the crystallites27 T. C. Marwick, J . Text. Sci., 1931, 4, 31.28 2. Krist., 1926, 64, 115.29 Zsigmondy, “ Kolloidchemie,” 4 A d . , 394 ff.30 R. Brill, 2. Krist., 1928, 68, 387; 1930, 75, 217; R.Brill and H. Pelzer,2. tech. Physik, 1929, 10, 663; 2. Krist., 1928, 72, 398; 1930, 74, 147; J.Bohm and F. Gauter, ibid., 1928, 69, 17332 ASTBURY :perpendicular to each reflecting plane and so build up a fairlycomplete picture of the shape of the crystallites as a whole. Thisis probably the most accurate method of estimating the size andshape of colloidal particles a t present available. It shows, forexample, that the cellulose micelles in ramie are on the averageabout- 55 A.U. thick but over 600 A.U. long,31 which means that thetotal internal surface of 1 g. of this fibre amounts to 7 x lo7 sq. ~ m . ~Similarly, Hengstenberg 31 has found 500 A.U. and 150 A.U. for thewidth and thickness, respectively, of the crystallites in stretchedrubber, with again a length of over 600 A.U., results which offer aready explanation of the fact that these crystallites, in very highlystretched rubber, assume a still more selective orientation thanis foundin cellulose fibres.13 Owing to their flatness, the crystallites in highlystretched rubber films lie with their long axes parallel t o the axis ofstretching and their broader sides roughly parallel to the plane ofthe film.The X-ray photographs of animal hairs point to dimensions ofthe same order for the crystallites or micelles of keratin as thosefound for other textile fibres, but as yet no quantitative results areavailable by the diffraction method.J. B. Speakman has, however,devised an interesting method, based on ingenious deductions fromcombined swelling and tensile data, of estimating the micelle sizein the wool fibre.32 He has concluded that the micelles are of theorder of 200 A.U.thick and are separated in the dry fibre by about6 A.U., this latter distance being increased to some 40 B.U. in thewater-swollen fibre. Thus, since the micelles are a t least ten timesas long as they are thick, the total internal surface is of the order oflo6 sq. em., and the total amount of intermicellar water adsorbedby wool from saturated air is 20.5% of the dry weight, a value inclose agreement with that found from a study by the same author ofthe effect of water adsorption on the rigidity of wool.Miscellaneous.The Molecular Weights of Pr~teins.~~-The results of the X-rayanalysis of protein fibres, such as natural silk and hair, affordevidence of the strongest kind in favour of the peptide chain theoryof protein structure.There seems to be little doubt that in thesesubstances long peptide chains are grouped together to form com-paratively thin bundles. By analogy with such crystallographic OFpseudo-crystallographic groupings of peptide chains, it has now been31 J. Hengstenberg, 2. Krist., 1928, 69, 271 ; R. 0. Herzog and D. Kriiger,J . Physical Chem., 1926, 34, 466.32 Proc. Roy. SOC., 1931, [ A ] , 132, 167.33 W. T. Astbury and H. J. Woods, Nature, 1931, 127, 663COLLOID CHEMISTRY. 333proposed that the results of T. Svedberg’s investigations 34 of theparticle-weights (“ molecular weights ”) of proteins by means of theultra-centrifuge can a t least be partly explained on the basis offamiliar crystallographic theory : for, if we assume that Svedberg’sunif.“ molecular weight ” of 34,500 is that of a single protein chain-and the single chains in protein textile fibres appear to haveweights of this order-it is then possible to derive the 2-f01dY3-fold, and 6-fold multiples of this weight by arguing that they aresimple crystallographic combinations based on the operation of2-fold and 3-fold symmetry axes.It should be noticed that nosecond-order symmetry elements, and therefore no enantiomorphouschains, are involved, with the result that the sequence 1, 2, 3, and6 times 34,500 may be expressed as well-known crystallographicgroupings corresponding to the space-groups Ci, Ci, Ci, D:, thelast-named being the space-group of quartz.The Denaturation of Proteilz~.~~-C.Rimington has suggested thatthe reversible intramolecular transformation which is undergone bythe keratin complex when animal hairs are stretched is probablyclosely analogous to the tautomeric change which accompanies thedenaturation of proteins in general. Denaturation, which can bebrought about by both mechanical and chemical agencies, involvesloss of solubility at the isoelectric point and some modification of thereactivity of the sulphur groups; but that there is no scission of themolecule is demonstrated by the absence of change in the acid- andbase-binding capacity, and in the osmotic pressure. Rimington’sdeduction from these observations is that denatured proteins are tobe classified with unstretched hair.I n particular, as he points out,affinity for water would be enormously diminished by the rearrange-ment of peptide linkages into what are virtually closed ring systems.I n this connexion, it is interesting to note that stretched hair isdefinitely in a more reactive state than unstretched hair.sThe pH Xtability Region of Insoluble Proteins.-Svedberg’s 34measurements of the stability of a number of soluble proteins as afunction of the pR of the environment have shown that each of themono-disperse proteins has a fairly wide stability region whichincludes the isoelectric point. By a totally different technique,Speakman 36 has now shown that the insoluble protein, wool keratin,also conforms to the same rule.The resistance of the wool fibre toextension is far less in either acid or alkaline solution than in dis-tilled water, which gives at once a method for studying the stabilityof keratin in various media. Speakman has measured the decrease34 Kolloid-Z., 1930, 51, 10.35 Nature, 1931, 127, 440; Trans. Faraday Soc., 1931, 2’9, 223.36 Nature, 1931, 127, 665334 ASTBURY :in the amount of work required to stretch a wool fibre by 30% of itsoriginal length, and has plotted the value so obtained against the pHof the medium in which the stretching was carried out. The finalcurve is shown in Fig. 3. It bears a remarkable resemblance to thecurves published by Svedberg and obtained by means of the ultra-centrifuge, even to the extent that the isoelectric point (a.t p H 4.8 forwool3') is located, not in the middle of the stability region, buttowards the region of lower p X values.Further details of theseimportant experiments will be found in the original communic-ation : 36 it will be sufficient here to state that Speakman ha,s shownthat, from the point of view of pH stability considerations, theparallel between wool keratin and the proteins studied by Svedbergis strikingly complete.FIG. 3.- 1 1 3 5 7 9 11 13P H spn Stability Curve of Wool Keratin (Speakman).MineraE Fibres.-In the field of inorganic fibres, X-ray analysesof silicate structures which have been carried out chiefly a tManchester by W. L. Bragg 38 and his co-workers have shown thatthe fibrous silicates, such as asbestos, resemble the organic fibres inthat they are also built up of long chains, based in these cases onthe linear repetition of certain characteristic silicon-oxygen group-ings.The most fundamental unit in silicate structure is a tetra-hedron of four oxygen atoms enclosing a silicon atom. The chainswhich are formed by the repeated linking of such units are in realitygigantic acid radicals held together sideways by the attractions ofthe metallic ions.37 J. B. Speakman, J. SOC. Dyers Col., 1925, 25, 172.3 8 8. Krist., 1930, 74, 237COLLOID CHEMISTRY. 335X-Ray Investigation of the Structure of a Single Ramie Fibre.-By means of an elegant micro-method devised by K r a t k ~ , ~ ~ it is nowpossible to take X-ray fibre photographs of localised areas which areconsiderably smaller than the cross-section of a single ramie fibre.K.Eckling and 0. Kratky 4O have applied this technique to the studyof the texture of the single biological cell which constitutes such afibre, but have failed to obtain photographs substantially differentfrom what is given by the usual macro-investigation of bundles offibres. From these results, it must be concluded that the micelleorientation throughout the fibre is no higher than the axially sym-metrical distribution which has always been met with in previousX-ray fibre analyses.PART II.-ELECTROEINETIC PHENOMENA.By D. C. HENRY.UNDER the heading electrokinesis is grouped a set of phenomena,originating a t the interface between two phases, in which theapplication of a tangential electric field produces a relative dis-placement of the two phases, or vice versa.The main phenomenaincluded are therefore : electrophoresis (cataphoresis), i.e., the motionof suspended particles through a liquid under the action of anapplied electric field, toget her with the converse effect--eZectro-phretic or migration potential ; and electrosmosis (electric endosmose),with the converse effect, stream potential, in which the passage of aliquid through a capillary tube or diaphragm is respectively theresult or the cause of a potential gradient in the same direction.In this Report will be reviewed in turn the apparatus and techniqueemployed in investigating these effects, the principal experimentalresults obtained, and finally the theoretical relationship betweenelectrokinesis and the electrical double Eayer, to the existence of whicha t interfacial surfaces electrokinetic phenomena are attributed.Since these subjects have only incidentally been referred to in pastAnnual Reports, the present survey will not be restricted to anyparticular period of years, although in general recent work willreceive most attention.For a general description of the phenomena,and for the classical investigations, reference can be made toSmoluchowski’s monograph l on “ Electric Endosmose ” or to oneof the standard textbooks on Colloids.239 2. Krist., 1930, 73, 567. 40 Z.physika1. Chern., 1930, [B], 10, 368.1 See Graetz, “Handbuch der Elektrizitijlt und des Magnetismus,” Bd. 2,p.379 (Leipzig, 1914) ; this monograph will be referred to as “ Sm.”2 E.g., H. Freundlich, “ Colloid and Capillary Chemistry ” (trsl. Hatfield,London, 1926); T. Svedberg, “ Colloid Chemistry,” 2nd. Ed. (New York,1928) ; H. R. Kruyt, “ Colloids,” 2nd Ed. (New York, 1930)336 HENRY :Apparatus and Technique.(1) The electrophoresis of suspended particles or colloidal solutionshas been investigated by three principal methods, vix., the moving-boundary method, the transference method, and the microscopicmethod.( a ) The moving-boundary method depends on a determination ofthe rate of motion, under a known potential gradient, of a horizontalsurface of separation of colloidal solution and clear supernatantliquid.The apparatus used is, as a rule, based on the well-knownU-tube of E. F. B ~ r t o n , ~ with or without the addition of wide-boretaps in the limbs designed to facilitate the formation of a sharpboundary ; since such taps almost inevitably introduce someirregularity into the bore of the limbs, and a perfect boundaryis readily obtainable without their use by sufficiently slow filling ofthe U-tube from below, they are not to be recommended exceptwhere speed of operation is a main consideration. Non-polarisableelectrodes have been employed with the object of preventingdisturbances by gas evolution and products of electrolysis. Thesame ends are achieved, in addition to other advantages, by placingthe main electrodes in long U-shaped side limbs in which products ofelectrolysis may accumulate without detriment ; subsidiary elec-trodes (taking negligible current) are fitted in the main vessel nearthe boundaries, and are used to measure and control the potentialfall in the latter.6Several critical discussions of moving-boundary technique havebeen published, of which that by H.R. Kruyt and P. C. van derWilligen appears especially valuable. Among the points discussedare the disturbances arising from heat generated by the current,uncertainties in the potential gradient a t the boundary, and themost suitable composition of the supernatant liquid. Kruytemploys intermicellar fluid, which may be obtained by centrifuging,3 Phil. Mag., 1906, [vi], 11, 436 ; A., 1906, ii, 275.A.Coehn, 2. Elektrochem., 1909, 15, 653; A., 1909, ii, 841 ; L. Michaelis,Biochem. Z., 1909,16,81; A., 1909, i, 277; F. 0. Howitt andE. B. R. Prideaux,J . Sci. Inst., 1930, 7, 89 ; A., 1930, 568.See, e.g., L. Michaelis, ref. (4).H. R. Kruyt and P. C. van der Willigen, Kolloid-Z., 1928, 44, 22; A . ,1928, 238; S. G. T. Bendien and L. W. Janssen, Rec. trav. chim., 1927, 46,739.Ref. (6); see also H. R. Kruyt, Kolloid-Z., 1925, 37, 358; A., 1926, 122;T. Svedberg, Colloid Symposium Monograph, 1923, 75; J. N. Mukherjee,Proc. Roy. SOC., 1923, [ A ] , 103, 102; J . Indian Chem. SOC., 1928, 5, 593; A.,1929, 143; L. Engel and W. Pauli, 2. physikal. Chem., 1927, 126, 247; A.,1927,511COLLOID CHEMISTRY. 337ultra-filtration, or coagulation 8 of the sol.Mukherjee givesreasons for preferring to use, in some cases, a suitably chosen elec-trolyte solution of the same conductivity as the sol. Whicheversupernatant liquid is used, a completely uniform potential gradientis both theoretically and experimentally unattainable. Mukherjee loattempts to overcome this difficulty by measuring the potentialgradient in the neighbourhood of the boundary with the help ofsmall non-polarisable electrodes inserted into the limbs of theelectrophoresis tube, while Kruyt l1 shows how the required correc-tion may be made by means of observations on the boundaries inboth limbs (incidentally supplying a rational explanation for thefrequently observed difference in the speeds of the two boundaries,which was attributed by E.17. Burton l2 to settling under gravity).The moving-boundary method has been adapted to use withcolourless sols, both by employing the Tyndall beam l3 to locatethe boundary, and also by photographing the fluorescence of proteinsols irradiated by ultra-violet light.14Numerous variations of apparatus have been described, somewith a view to biological requirements, others designed primarilyfor rapid semi-qualitative observations.15The highest precision a t present attainable by the moving-boundary method under favourable conditions and with all dueprecautions would appear to be about 2%,16 but only a fewinvestigations can lay claim to a higher precision than 5%, andF. Powis, J., 1916, 109, 739; A., 1916, ii, 521; S.W. Pennycuick, J.,1930, 1447 ; A., 1930,994.J . Indian Chem. SOC., 1928, 5, 593; A., 1929, 143; J. N. Mukherjee,S. P. Rai-Choudhuri, and A. S. Bhattacharyya, ibid., p. 735; A., 1929, 261.lo Proc. Roy. SOC., 1923, [A], 103, 102.l1 Ref. (6).l2 Proc. Roy. SOC., 1919, [ A ] , 95, 480; A., 1919, ii, 323.l3 H. R. Kruyt, Kolloid-Z., 1925,37, 358; A . , 1926, 122; H. R. Kruyt andH. J. C. Tendeloo, Kolloidchem. Beih., 1929, 29, 413; A., 1929, 1381 ; A. V.Dumanski and A. G. Kniga, Kolloid-Z., 1926, 39, 40; A., 1926, 679.l4 T. Svedberg and E. R. Jette, J . Amer. Chem. SOC., 1923, 45, 954; A.,1923, i, 614; N. D. Scott and T. Svedberg, ibid., 1924, 46, 2700; A., 1925, ii,204; T. Svedberg and A. Tiselius, ibid., 1926, 48, 2276; A., 1926, 1104.l6 For examples of biological uses, see C.Todd, Brit. J. Exper. Path., 1927,8, 369; F. VIBs, Arch. Physique biol., 1927, 6, 139; A. P. Krueger, R. C.Ritter, and S. P. Smith, J. Exp. Med., 1929, 50, 739. For qualitativeapplications, see W. D. Horne, Xnd. Eng. Chem., 1928, 20, 1147; A., 1929,44; G. Ettisch and D. Deutsch, Physikal. Z., 1927, 28, 153; A., 1927, 310;A. Janek, Kolloid-Z., 1924, 34, 103; A . , 1924, ii, 247; R. Fiirth, ibid., 1925,37, 200; A., 1925, ii, 1057. A U-tube apparatus for use with oil emulsionshas been described by H. Limburgh, Rec. trav. chim., 1926, 45, 854.16 See, e.g., H. R. Kruyt and P. C. van der Willigen, ref. (6) ; J. N. Mukherjee,S. P. Rai-Choudhuri, and A. N. Ilao, J . Indian Chem. SOC., 1928, 5, 697; A.,1929,261338 HENRY :it is quite uncertain how far either of these limits represents theaccuracy of determination of a true electrophoretic velocity.( b ) The transference method depends on the same principles as thedetermination of an ionic transport number by Hittorf’s method.The apparatus may consist of two (or three) vessels connected bysyphons,17 of a two-compartment tube as used for ionic transportnumbers,l* or of a U-tube apparatus,lS similar t o that used in themoving-boundary method, arranged to prevent access of the colloidto the electrodes.Engel and Pauli claim a precision of 5 Z%, and Paine one of5% by the transference method.This method has the advantageof eliminating the uncertainty in the potential gradient which is thechief difficulty in the moving-boundary method.Its own limit isprobably set by analytical considerations.( c ) The microscopic method differs from those described above inthat the motion of individual particles is observed in the microscopeor ultramicroscope, which is a considerable advantage for theoreticalstudies. On the other hand, it is inapplicable to concentrated oramicroscopic sols, and, in consequence of the Brownian movement,can only be expected to give representative results by the observ-ation of large numbers of particles. P. Tuorila20 has shown thatthe indivual observations conform to Gauss’s law of errors, andhence calculates the number of observations required to secure agiven degree of precision in the mean. For a general description ofthe method, reference may be made to Smoluchowski’s mono-graph 21 or to one of the text-books cited.A general discussion ofthe method has been given by Kruyt.22 Observations are usuallymade by timing particles across a pair of eyepiece cross-wires, buttwo alternative methods, one involving photographic registrati~n,~~the other the use of alternating applied potential^,^^ have beendescribed, and appear to have decided advantages over the moreusual method. A rotating electric field has also been employed.251’ G. Varga, Kolloidchem. Beih., 1919,11, 3 ; A . , 1921, ii, 371 ; R. Wintgen,2. physikal. Chem., 1922, 103, 238; A . , 1923, ii, 78; H. H. Paine, Trans.Paraday Xoc., 1928,24,412 ; A., 1928, 1093.Is R. Wintgen and M. Biltz, 2.physikal. Chem., 1923, PO’S, 403 ; A . , 1924,ii, 156; R. Wintgen and H. Lowenthal, ibid., 1924, 109, 378; A., 1924, ii,534.19 L. Engel and W. Pauli, ref. (7); J. W. McBain and R. C. Bowden, J . ,1923,123, 2417.20 Kolloid-Z., 1928, 44, 11; A., 1928, 235.22 Refs. (6) and (7).23 T. Svedberg and H. Anderson, KoLZoid-Z., 1919, 24, 156 ; A., 1919, ii, 315.24 Idem, ibid. ; 0. Bliih, ibid., 1925, 37, 267; Ann. Physik, 1926, 79, 143;A., 1926, 23, 676.25 E. M. Pugh and C. A. Swartz, Physical Rev., 1930, 36, 1495; A., 1931, 36.21 Sm.,p. 382COLLOID CHEMISTRY. 339Electrophoresis cells have been described by : T. Svedberg,26 H. R.KruytY2’ P. Tuorila 28 (rectangular cemented cells with platinumelectrodes); H. R. Kruyt and A. E. van ArkelZ9 (as above, butelectrodes arranged to render gas evolution innocuous) ; K.van derGrinten 3O (rectangular cell, partially open, quick in use, platinumelectrodes) ; S. Mattson 31 (circular section all-glass cell, easilycleaned and filled, platinum electrodes); J. H. N o r t h r ~ p , ~ ~ M.Kunitz 33 (rectangular cemented cell, non-polarisable electrodes) ;J. H. Northrop and M. K ~ n i t z , ~ ~ H. Abramson35 (cell drawn fromglass tube to flat section, easily cleaned and filled, non-polarisableelectrodes). Extreme cleanliness is essential, and the all-glass cellsare preferable to those with cemented joints. Unfortunately noneof the all-glass cells hitherto described has a true rectangularcross-section, which in certain circumstances (see below) is mostdesirable.The observed velocities of the particles are compounded of thetrue electrophoretic velocity and the streaming motion of theliquid set up by electrosmosis a t the cell walls.With a closed cell,the streaming motion is in one direction near the walls, and in theopposite direction in the centre of the cell. For a cell whose depthis small compared with its width, R. Ellis 36 and M. Smoluchowski 37have shown how the two velocities may be disentangled by meansof observations made a t different depths in the cell; for such cellsthe precise form of the narrow sides is immaterial, and certainpatterns of all-glass cells are suitable. With deeper cells such as aredesirable for use with the slit ultramicroscope, Smoluchowski’scalculation is not valid, while Ellis’s method of correction, though intheory applicable, is impossibly cumbersome in practice ; instead,the correction needs to be calculated by the formuls published byC.G. Sumner and D. C . Henry,38 which are valid for any ratio ofdepth to width, but require the cross-section t o be strictly rectangu-lar. The use of either method of correction presupposes a com-pletely closed cell, and one cannot a priori assume the process to beapplicable to a cell such as van der Grinten’s. It appears, however,26 Nova Acta (Upsala), 1907, [iv], 2, No. 1, 149; Kolloid-Z., 1919, 24, 156.27 Ibid., 1916, 19, 161.28 Ref. (20). 29 Kolloid-Z., 1923, 32, 91 ; A., 1923, ii, 226.30 Compt. rend., 1924, 178, 2083; J . Chim. physique, 1926, 23, 226; A.,31 J .Physical Chem., 1928, 32, 1532 ; A . , 1928, 1323.32 J. Cen. Physiol., 1922, 4, 629.34 Ibid., 1925, 7, 729.36 2. physikal. Chem., 1911, 78, 321; A., 1912, E, 13.37 Op. cit., p. 382.3 8 Proc. Roy. SOC., 1931, [A], 133, 130; A., 1232.1934, ii, 664; 1926,467.33 Ibid., 1924, 6, 413.35 Ibid., 1929, 12, 469; A., 1929, 478340 HENRY :from his results, as recalculated by H. Abram~on,~~ that the surfacetension a t the open ends is sufficient to prevent any bodily displace-ment of the liquid, so that Smoluchowski’s formula may be applic-able; van der Grinten’s own method of calc~lation,~O based on hisclaim that the streaming velocity is zero in the centre of the cell, is,as Abramson shows, based on a misinterpretation of his results, andis almost certainly erroneous.To avoid these complications,M. Mooney 41 has devised a cell in which the return flow takes placein an auxiliary and much wider tube ; the flow in the observationaltube is then sensibly constant over the whole cross-section, whichsimplifies comparative observations.Vertical electrophoresis tubes have also been used for the investig-ation of the movement of gas bubbles and oil drops,42 the electro-phoretic force being directly compared with the gravitational forceby methods analogous to those employed by hlillikan with oil dropsin air. For the same purpose there have been employed 43 horizontalcircular tubes which are kept in rotation about a horizontal axis inorder to maintain the bubble or drop on the axis of the tube.The precision of the microscopic method probably exceeds that ofall but the best determinations by the other two methods, and maybe better than &- 2%.( d ) Miscellaneous electrophoretic methods.Qualitative 44 andquantitative 45 electrophoretic investigations have been made byobservation of the deflexion of a suspended fibre or needle in theelectric field. Other methods employed include the motion of asingle drop of mercury46 and the lateral deflexion of a stream ofmercury droplets4’ or of a jet of colourless sol; 48 in the latter case39 J . Physical Chem., 1931, 35, 289; A., 429.40 Also adopted by H. R. Kruyt and G. S. de Kadt, Kolloidchem. Beih.,41 Physical Rzv., 1927, 29, 218 ; A., 1928, 1315.42 Idem, ibid., 1924, 23, 396; J.W. McBain and R. C. Williams, ColloidSymposium Annual, 1930, 105 ; D. A. Newton, Phil. Mag., 1930, [vii], 9, 769 ;A., 1930, 858.43 H. A. McTaggart, ibir?., 1914, [vi], 2’7, 297 ; 28, 367 ; 1922, [vi], 44, 387 ;Trans. Roy. SOC. Canada, 1924, 18, iii, 129; A., 1914, ii, 762; 1925, ii, 509; T.Alty, Proc. Roy. SOC., 1924, [A], 106, 315; 1926, [A], 110, 178; A., 1926,239; B. W. Currie and T. Alty, ibid., 1929, [A], 122, 622; A., 1929, 390.44 P. A. Thiessen, 2. anorg. Chem., 1929, 181, 379; F. Fairbrother andF. Wormwell, J., 1028, 1991; A., 1028, 1097; A. Garrison, J . Amer. Chem.SOC., 1923, 45, 37; A., 1923, ii, 115.1931, 32, 249; A., 796.4 5 C. G. Sumner and D. C. Henry, ref. (38).46 S. Bodforss, 2. Elektrochem., 1923, 29, 121.47 A.Frumkin, J. Russ. Phys. Chem. SOC., 1917, 49, 207.48 R. H. Humphry, Kolloid-Z., 1926, 38, 306; A., 1926, 577; R. H. Hum-phry and R. s. Jane, Trans. Paraday SOC., 1926, 22, 420; A., 1926, 1204;E. A. Lantz and 0. A. Pickett, Id. Eng. Chem., 1930, 22, 1309COLLOID CHEMISTRY. 341the jet was made visible by means of the Topler “ schlierenEff ekt.”(2) Electrophoretic Currents.-When particles are allowed to fall,or bubbles to rise, through a liquid, under the action of gravity, apotential gradient is set up in the liquid parallel to the direction ofmotion. This phenomenon, the converse of electrophoresis, hasso far only led to qualitative results. The classical investigationsare those of Dorn, Makelt, Billiter, and The only recentinvestigations have been published by E.3’. Burton and J. E.Currie 5O and by R. D. Kleeman and C. R. P i t t ~ . ~ l(3) E2ectrosmosis.-For a full account of the earlier work in thisfield, reference should be made to Smoluchowski’s monograph. 52For the investigation of electrosmosis through diaphragms (whetherin the form of a membrane or of a plug of powder) almost all formsof apparatus are in principle based on that of J. Perrin,53 in whichthe passage of liquid through the diaphragm is indicated by themotion of a meniscus in a capillary tube connected to the vessel onone side of the diaphragm. The most notable modification is thatof B r i g g ~ , ~ ~ who connected the capillary so as to serve as a returnpath for the liquid; a bubble in the capillary serves to indicate theelectrosmotic flow.Platinum electrodes were used, and conse-quently the apparatus had t o be open to the air to allow for theescape of evolved gases. A. Gyemant 55 and F. Fairbrother andH. Mastin employ non-polarisable electrodes which allow theapparatus to be constructed as a closed system.The potential fall across the diaphragm has been calculated bymost workers in terms of the total current flowing, the specificconductivity of the liquid, and the ‘‘ effective dimensions ” of thediaphragm; the last magnitude is determined by calibration witha liquid of known conductivity. Pairbrother and Mastin pointout that this mode of calculation assumes the conductivity of theliquid in the pores of the diaphragm to be identical with that of theliquid in bulk, which is known both theoretically57 and experi-mentally58 not to be the case.These authors therefore use sub-49 See Sm., p. 385.5O Phil. Mag., 1925, [vi], 49, 194; A., 1925, ii, 531.51 J . Physical Chem., 1925, 29, 508; A., 1925, ii, 659.52 Op. cit., pp. 366, 388, 401.53 J . Chim. physique, 1904, 2, 601; 1905, 3, 50; A., 1905, ii, 138.54 T. R. Briggs, H. S. Bennett, and H. L. Pierson, J . Physical Chem., 1918,See also A. Strickler and J. H. Mathews, J . Amer. 22, 256; A., 1918, ii, 214.Chem. SOC., 1922, 44, 1647 ; A., 1922, ii, 688.55 2. physikal. Chem., 1922,103, 260; A., 1923, ii, 52.56 J . , 1924,125, 2319; A., 1925, ii, 47.5 8 F. Fairbrother, J., 1924, 125, 2495; A., 1925, ii, 129.5 7 Sm.,p. 396342 HENRY :sidiary non-polarisable electrodes to make a direct determinationof the potential fall across the diaphragm.Another source of errorin the usual electrosmotic technique arises from the fact that, owingpartly to viscosity and partly to surface tension, a quite appreciablepressure difference between the two ends of the apparatus is requiredto move the bubble in the capillary. This difference causes a certainamount of back flow through the diaphragm, with the result that theelectrosmotic flow per unit current, which should be independentof the permeability of the diaphragm, is found to diminish as thepermeability increases.59 The error is minimised by using as widea capillary as is consistent with the sensitivity required, by ensuringabsolute freedom from grease, and by avoiding the use of undulypermeable diaphragms.60 The error may be allowed for by determin-ing either the pressure required to move the bubble in a blankexperiment, or the pressure difference established during the electr-osmotic flow experiment, a differential manometer being used.6lThe reproducibility attainable in electrosmotic experiments is,under specially favourable conditions, with well-defined diaphragmsand pure liquids, as high as -J= 1% ; 62 with solutions, and especiallywith diaphragms liable to vary in packing, it is certainly much lower.(4) The method of stream potentiaE G3 has been applied in the main(though not exclusively) to investigations with capillary tubes ofglass or quartz, and is carried out by forcing liquid from one vesselto another under a well-defined and constant pressure differencewhich is, as a rule, provided by a compressed gas. The potentialdifference produced is measured by a compensation method with thehelp of metallic or non-polarisable electrodes in, or connecting with,the terminal vessels.Typical forms of apparatus are described byH. R. ICruyt and P. C. van der Willigen,6* H. Freundlich and P.R ~ n a , ~ ~ and H. Eachs and J. Biczyk.66 The last-named workersfound that a great improvement in reproducibility resulted from acareful shielding from electrostatic influences of all parts of thecompensation circuit, and from a thorough control of the carbon59 See, e.g., A. Strickler and J. H. Mathews, ref. (54) ; J.N. Rlukherjee andP. Kundu, J . Indian Chem. SOL, 1926, 3, 335; A., 1927, 409.60 F. Fairbrother and M. Balkin, J., 1931, 389; A., 434.61 Unpublished experiments made in the Reporter’s laboratory show thatthe error due to back pressure may be considerable, and that the two methodssuggested for applying a correction give concordant results, the latt,er beingthe more trustworthy.62 In this connexion, see F. Fairbrother and H. Varley, J., 1927, 1584;A., 1927, 826; H. C. Hepburn, Proc. Physical Xoc. 1926, 38, 363; A., 1926,1100.63 See Sm., pp. 372, 378. 64 Kolloid-Z., 1928, 45, 307; A., 1928, 1091.6 6 Xitzungsber. Preuss. Akad. Wiss. Berlin, 1920, 20, 397.6 6 2. physikal. Chem., 1930, [A], 148, 441; A., 1930, 1119COLLOID CHEMISTRY. 343dioxide content of the water used, to variations in which the electro-kinetic potential is very sensitive. It is further essential 67 that therate of flow employed should lie well below the limit a t whichPoiseuille’s law ceases to hold.With these precautions results areobtainable with st given capillary which are reproducible to within2y0 both in pure water and in electrolyte solutions.Stream-potential measurements have also been carried out withporous diaphragms; typical forms of apparatus are described byD. R. BriggsMention must be made of a special technique by which the electso-kinesis of proteins may be more easily investigated than by themethods employing the Tyndall beam or fluorescence in ultra-violetlight. It has been shown 7O that many solids adsorb a layer ofprotein from aqueous solufion and behave electrokinetically likeparticles of protein.This has been applied to electrophoresis bythe micoscopic method, with particles of glass or quartz,71 to themoving-boundary method with colloidal gold particles,72 and to thestream-potential method with a quartz capillary.73 Results areobtained which are concordant among themselves and with thoseobtained by the fluorescence method.and by W. McK. Martin and R. A. G ~ r t n e r . ~ ~Experimental Results.The observational data of electrokinetic investigations are quanti-ties such as “ the electrophoretic velocity under unit potentialgradient,” “ the electrosmotic flow per coulomb,” or “ the streampotential per atmosphere pressure difference ” ; in view of uncer-tainties in the theoretical interpretation of these data, J.W.McBain 74 has strongly urged that the results of electrokineticresearches should be recorded in terms of the observed magnitudesonly. While it is undoubtedly highly desirable that the lattershould invariably be included in the published report to facilitate67 See, e.g., H. R. Kruyt and 1’. C. van der Willigen, ref. (64) ; H. Freundlichand G. Ettisch, 2. physikal. Chem., 1925, 116, 401 ; A., 1925, ii, 873.6 8 J . Physical Chem., 1928,32, 641; A., 1928, 713.69 Ibid., 1930, 34, 1509; A., 1930, 1124.7o H. Davis, J . Physiol., 1922, 57, 16; H. Freundlich and H. Abramson,2. physikal. Chem., 1928, 133, 51; A . , 1928, 587; H. Abramson, J . Amer.Chem.SOC., 1928, 50, 390; A., 1928, 364; Colloid Symposium Monograph,1928, 115; J . Gen. Physiol., 1930, 13, 169, 657; A., 1930, 1250; J . PhysicalChem., 1931, 35, 289 ; A., 429.71 H. Abramson, ref. (70).72 E. B. R. Prideaux and F. 0. Howitt, Proc. Roy. SOC., 1929, [A], 126,126;73 D. R. Briggs, J . Amer. Chem. Soc., 1928, 50, 2358; A., 1928, 1193.74 J . Physical Chem., 1924, 28, 706; A., 1924, ii, 594; Colloid SymposiumA., 1930, 169.Monograph, 1926, 7344 HENRY :re-interpretation in the event of any alteration in the theoreticalpoint of view, it would appear inconvenient and cumbersomeentirely to avoid discussion in terms of the current theories, pro-vided that the underlying assumptions are recognised; in thisReport, therefore, we shall follow the usual practice and adopt thecommonly accepted interpretations of electrokinesis, based on thetheories of Helmholtz and Smoluchowski, 75 bearing in mind theprobability that these may require modification in the future.Onthese theories the observational data in question are related bysimple formuls 76 to a magnitude known as the “ electrokineticpotential ” (designated <), and it is to an evaluation and interpret-ation of this quantity, and of its variation with conditions, that themajority of electrokinetic investigations are directed.The <-Potential at the Interface between Pure Phases.-Coehn’srule,77 which states that, of two dielectrics in contact, that withthe higher dielectric constant is charged positively, is not confirmedby recent investigations, though there are indications of a morefundamental generalisation of which it may in certain circumstancesbe the manifestation.A. Strickler and J. H. mat hew^,^^ and morerecently W. McK. Martin and R. A. G ~ r t n e r , ~ ~ have investigatedthe <-potential a t the interface cellulose-organic liquid. Theformer authors conclude that the magnitude of the electrokineticeffect, but not its sign, is roughly determined by the dielectricconstants, while both investigations lead to the conclusion that theorientation of polar molecules a t the interface is a determining factor.This idea gains quantitative support from the work of F. Fairbrotherand M. Balkin,so who find that of the 14 liquids used by them forwhich dipole moments are known, < for all but one (acetone) is alinear function of the dipole moment multiplied by the molarsurface area ; in agreement with this, the non-polar liquids benzeneand carbon tetrachloride give zero electrosmosis.The non-zeroresult obtained by Strickler and Mathews with benzene they attri-bute to impurities in the benzene. F. Pairbrother and F. Worm-well 81 have made qualitative observations of the electrokineticpotential of solids against their own melts; all the solids investig-ated (except o-chlorophenol and benzene, which gave zero results)were found to be positive against the corresponding liquids. It isnot certain whether this is in contradiction to Coehn’s rule or not,as there is considerable uncertainty about the dielectric constantsof solids at their melting points.75 H. von Helmholtz, Wied.Ann., 1879, 7, 3 5 7 ; “ Gesamm. Abhandl.” ii,76 See p. 349.p. 855; Sm., p. 379; M. von Smoluchowski, Krakau Anzeiger, 1903, p. 182.7 7 Sm., p. 401. 78 Ref. (54).Ref. (69). so Ref. (60). Ref. (44)COLLOID CHEMISTRY. 345The Influence of Electrolytes in Aqueous Solution on the &Potential.-The older views on this subject may be summed up in the generalis-ations : (1) The ion of opposite sign to the charge on the solid phasehas a preponderating influence, and tends to lower the numericalvalue of C; (2) the efficacy of an ion in influencing the value ofC increases with its valency and with its adsorbability.The evidence for the general truth of the “ valency effect ” isample; reference may be made to the text-books, and amongnumerous more recent papers to those of H.Freundlich and H. P.Zeh,s2 F. Fairbrother and H. Mastin,S3 and H. R. Kruyt and P. C.van der Willigen. s4The evidence for the “ adsorbability effect ” is more equivocal,since the electrokinetic effect is sometimes taken as a measure ofadsorbability ; 85 a t the same time it is just those ions which on othergrounds are known, or by analogy may be expected, to be stronglyadsorbed, which exert an influence on C greater than is to be anti-cipated from their valency ; examples are hydrogen, hydroxyl,heavy-metal, complex, and organic ions, especially those of highmolecular weight.s6The first generalisation has required considerable modification.Limiting ourselves, for simplicity of discussion, to the case of anegatively charged solid phase, we find, in the first place, that saltsof a univalent kation frequently cause in low concentration anincrease 87 in the numerical value of C, to be followed in higherconcentrations only by the decrease which is to be expected if the“ ion of opposite charge ’’ exerts the preponderating influence.This is more particularly the case when the anion is of high valencyor adsorbability, as, e.g., FeC6N6”” with arsenious sulphide 501~8882 Z . physikal. Chem., 1924, 114, 65; A., 1925, ii, 115.83 J., 1925, 127, 322; A., 1925, ii, 302.84 KoZToid-Z., 1928,45, 307; A . , 1928, 1091.85 See, e.g., J. N. Mukherjee and H. L. Ray, J. Indian Chem.Soc., 1924, 1,173; A., 1925, ii, 385; J. N. Mukherjee and P. Kundu, ibid., 1926, 3, 335;A., 1927, 409.8 6 See, e.g., H. R. Kruyt and P. C. van der Willigen, ref. (84); J. N. Muk-herjee and B. C. Roy, J., 1924,125, 476; A., 1924, ii, 313; C. E. A. Winslowand E. H. Fleeson, J. Gen. Phylsiol., 1926, 8, 195; A., 1926, 324; P. Tuorila,Kolloidchem. Beih., 1928, 27, 44; A . , 1928, 950; D. R. Briggs, J. PhysicalChem., 1930,34, 1326.8 7 See, e.g., H. R. Kruyt, Kolloid-Z., 1918, 22, 81; A., 1918, ii, 289; H. C .Hepburn, Proc. Physical SOC., 1926, 38, 363 ; A., 1926, 1100 ; A. Ivanitzkajaand M. Proskurnin, Kolloid-Z., 1026, 39, 15; A . , 1926, 679; L. Orlova, Z .physikal. Chem., 1928, 134, 345; A . , 1928, 701; A. von Buzagh, Kolloid-Z.,1929,48,33 ; 49,35 ; A., 1929,763,1236 ; 1%.Lachs and J. Biczyk, 2. physikal.Chem., 1930, [ A ] , 148,441 ; A., 1930, 1119.88 H. Freundlich and H. P. Zeh, ref. (82)346 HENRY :or hydroxyl with manganese oxide,@ platin~m,~O kaolin,g1 and glass.92I n the second place, we commonly find that the nature of the anionhas quite a considerable influence on the form of the C-c curve overthe whole range of concentrations.93 Similar conclusions hold,mutatis mutandis, for positively charged solids. It would thus appearthat modification of the c-potential is caused not merely by adsorp-tion of the ion of opposite charge, a process which is easily under-standable since it can be attributed to simple electrostatic attraction,but also by adsorption of the ion of like charge, which is not soreadily explicable.The ability of a charged surface to adsorb ionsof like charge is further exemplified by the frequency with which amultivalent or strongly adsorbed kation is able not only to reduce ther-potential of a negative supface to zero, but even to reverse i t ; 94the ions which accomplish this latter feat would seem necessarilyto be adsorbed in opposition to electrostatic forces. This is, ofcourse, not impossible, for there certainly exist modes of adsorptionwhich are not directly electrostatic in origin, but it must not beforgotten that a change in the r-potential is not inevitably bound upwith a corresponding change in the electric charge on the solidphase.I n experiments with a salt-like solid, the solubility of the saltwhich may be formed by an ion of the added electrolyte with oneof the ions of the solid appears to have a considerable influence onthe apparent ad~orbability.~~89 B.Ghosh, J., 1926, 2605; A., 1926, 1203.90 S. W. Pennycuick, J., 1930, 1447; A., 1930, 994.91 A. Reifenberg, Kolloid-Z., 1930, 53, 162.92 H. R. Kruyt and P. C. van der Willigen, ref. (84).93 See, e.g., J. N. Mukherjee and H. L. Ray; J. N. Mukherjee and P. Kundu,ref. (85); J. N. Mukherjee and S. G. Chaudhury, J . Indian Chem. SOC., 1925,2, 296; A., 1926, 352; J. Glixelli and J. Wiertelak, Kolloid-Z., 1927, 43, 85;1928, 45, 197; A., 1927, 1139; 1928, 953; A. Rabinerson, ibid., 1928, 45,122 ; A., 1928, 833.94 See, e.g., A. Boutaric and G. Perreau, Compt. rend., 1927, 184, 814; A.,1927, 410; B.Ghosh, ref. (89); J . N. Mukherjee and B. C. Roy, P. Tuorila,C. E. A. Winslow and E. H. Fleeson, ref. (86); A. von BuzBgh, ref. (87); S.W. Pennycuick, ref. (90); F. Fairbrother and H. Mastin, ref. (83); A. J.Stamm, Colloid Symposium Monograph, 1928, 361; A., 1929, 759; H. Lim-burgh, Rec. trav. chim., 1926, 45, 854; A., 1927, 109.S5 Thus, e.g., H. R. Kruyt, A. C. W. Roodvoets, and P. C. van der Willigen(Colloid Symposium Monograph, 1926, 304; A., 1928, 17) attribute a risingelectrophoresis curve t o changes in the dielectric constant, while A. J. Rabino-vitsch and E. B. Fodimann (2. physillal. Chent., 1931, 154, 255; A., 682)attribute the same effect to alterations in the structure of the electrical doublelayer brought about by interchange adsorption.96 J.N. Mukherjee and H. L. Ray; J. N. Mukherjee and P. Kundu; ref.(85)COLLOID CHEMISTRY. 347With proteins, as might be expected from their amphotericnature, the hydrogen-ion concentration of the solution has a pre-ponderating effect, and not a great deal is known about the effectsof other ions. Reference may be made to publications alreadycited 97 and to the numerous papers of J. L ~ e b . ~ sClosely related to the subject matter of this section is the study ofthe influence of dilution on the <-potential. Increase,99 decrease,land even reversal of C has been observed to take place on dilutionof a colloidal solution. These effects are presumably due to areadjustment of the electrolyte adsorption equilibrium betweencolloidal particle and medium, and the result obtained will dependon the shape of the C-c curve and on the initial electrolyte content ;for example, a silver iodide sol prepared in the presence of excesssilver nitrate is positive, whilst silver iodide is negative to purewater; dilution of the former sol naturally therefore leads to areversal of the sign of <.The Influence of Non-electTolytes on the <-Potential.-This has beenthe subject of a few investigations.Alcohols, acetone, urea, andcane sugar in considerable concentration * reduce the electrophoreticvelocity (v) in all cases examined; in general, the same applies tothe magnitudes qv/D (proportional to <) and qv (proportional tothe surface charge in an electrical double layer of constant thickness).A variation in the structure of the double layer therefore appears tobe indicated.6 An extensive investigation 7 has recently beencarried out using quartz powder with quite dilute aqueous solutionsof various alcohols, amines, and fatty acids. The electrophoreticvelocity is lowered by the acids and the four lowest aliphatic alcohols,but raised by amyl and hexyl alcohols and by both aromatic andaliphatic amines-by the latter in surprisingly low concentration.97 Refs.(13), (71), (72), and (73).98 J . Gen. Physiol., 1919-1923.g9 S . S. Bhatnagar and D. C. Bahl, Kolloid-Z., 1930, 50, 48; A., 1930, 291;I. Remesov, Biochem. Z., 1930,218, 86; A., 1930, 416.1 J. N. Mukherjee, S. G. Chaudhury, and S.P. Rai-Choudhuri, J. IndianChem. SOC., 1927, 4, 493; A., 1928, 15.2 H. R. Kruyt and P. C. van der Willigen, 2. physikal. Chern., 1928, [ A ] ,139, 53; A., 1929, 136; A. Lottermoser and W. Riedel, Kolloid-Z., 1930, 51,30 ; A., 1930, 696.H. R. Kruyt and P. C. van cler Willigen, ref. (2).4 S. S. Bhatnagar and D. C. Bahl, ref. (99); J. N. Mukherjee, S. G. Chaud-hury, and S. P. Rai-Choudhuri, ref. ( l ) , see above; J. N. Mukherjee, S. P.Rai-Choudhuri, and A. N. Rao, J . Indian Chem. SOC., 1928,5,697; A., 1929,261.5 7 is the viscosity and D the dielectric constant.6 See G. Ettisch and A. Zwanzig, 2. physikaE. Chem., 1930, [A], 147, 151 ;7 S. H. Whang, Kolloidchem. Beih., 1931, 32, 169; A . , 429.A., 1930, 697348 HENRY :I n the presence of non-electrolytes, the <-c curves for electrolyteadditions are modified in form.sThe Eflect on Electrophoresis of Irradiation.-This has beenexamined with visible and ultra-violet light and wit’h X-rays,lo andfound to be small or non-existent.Surface Conductivity.-It was predicted by Smoluchowski l1 thatthe existence of an electrical double layer at an interface must giverise to the phenomenon of surface conductivity.This was con-firmed by Stock,12 and has recently been observed by severalworkers ; l3 in the last-quoted paper Smohchowski’s theoreticalrelation between the surface conductivity and the c-potential isemployed to calculate relative values for the thickness of the doublelayer and for the fixed charge. Some recent experiments l4 throwconsiderable doubt on the validity of the relation in question, sincefor glass in contact with a solution of hydrogen chloride in drybenzene, cyclohexane, and carbon tetrachloride, there was no cor-relation between the surface conductivity and the <-potential.Thecarbon tetrachloride solution, for example, which gave much thegreatest surface conductivity, showed zero electrosmosis at allconcentrations of hydrogen chloride.The Electroviscous B@ect.-M. von Smoluchowski l5 showed thatthe apparent viscosity of a suspension of charged particles shouldbe greater than that of a similar suspension of uncharged particles,and deduced a relationship between this “ electroviscous effect ”and the <-potential. The former has been studied in both lyo-philic l6 and lyophobic l7 sols, and provides a valuable method forstudying changes in the C-potential in cases not readily amenableto ordinary electrokinetic technique .Electrokinesis and the Stability of Colloidal Solutions.-That a* J.N. Mukherjee, S. P. Rai-Choudhuri, and A. N. Rao, ref. (4), p. 347.9 K. Schaum and P. Friederich, 2. wiss. Phot., 1924, 23, 98.Physik, 1929, 56, 6S4; D. A. Newton, Phil. Mag., 1930, [vii], 9, 769.10 S. S. Bhatnagar, R. S. Gupta, K. G. Mathur, and K. N. Mathur, 2.11 Sm., p. 396.l3 F. Fairbrother, J., 1924, 125, 2495; A . , 1925, ii, 129; J. W. McBain,C. R. Peaker, and A. M. King, J . Amer. Chem. SOC., 1929, 51, 3294; A . , 1930,37; J. W. McBain and C. R. Peaker, J . Physical Chem., 1030, 34, 1033; A .,1930, 704; H. B. Bull and R. A. Gortner, ibid., 1931, 35, 309; A . , 435.l2 Sm., p. 398.14 F. Fairbrother and M. Balkin, J . , 1031, 1564; A . , 014.l5 Kolloid-Z., 1916, 18, 190.l6 H. R. Kruyt and H. G. Bungenberg de Jong, 2. physikal. Chem., 1922,100, 25 ; Kolloidchem. Beih., 1928, 28, 1 ; H. G. Bungenberg de Jong, Rec.trav. chim., 1924, 43, 189; R. H. Humphry and R. S. Jane, Trans. ParadaySOC., 1926,22,420; Kolloid-Z., 1927,41,293; B. J. Holwerda, Rec. trav. chim.,1928, 47, 248 ; H. J. C. Tendeloo, ibid., 1929, 48, 23.17 Idem, Kolloid-Z., 1927, 41, 290; N. R. Dhar and S. Ghosh, ibid., 1929,48, 43COLLOID CHEMISTRY. 349relationship exists between the stability of lyophobic sols and thecharge on the colloidal particle is undoubted, the general view beingthat a sol becomes unstable when the C-potential is reduced below acertain “ critical potential.” 18 This generalisation appears to bevalid in many cases, but apparently fails when the coagulating ionis of low valency and adsorbability. Space does not permit a dis-cussion of the considerable volume of work which has been done onthis problem of stability and the critical potential ; some of the mostprominent among recent publications on the subject are referred to.19The Theory of Electrokinesis.Helmholtz’s well-known theory of electrokinesis 2O was based onthe suggestion made by Quincke that there exists at the interfacebetween two phases an “ electrical double layer ” consisting of twolaminar distributions of electrification, equal in amount but oppositein sign, forming a kind of parallel plate condenser of which the“inner sheet’’ is firmly attached to the rigid phase, while the“ outer sheet ” resides in the mobile phase.This theory, with aslight modification introduced by Pellat, was extended and general-ised by Smoluchowski,20 and leads to the fundamental equations :U / X = D</47q (electrophoresis) . . . . (1)V / J = E/P = D < / ~ x ~ K (electrosmosis and stream potential) . (2)(U is the electrophoretic velocity under potential gradient X , V thevolume of liquid electrosniotically transported per second by acurrent J , and E the stream potential set up by a pressure differenceP ; D, 3, and K are respectively the dielectric constant, viscosity,and specific resistance of the liquid). Subject to certain restrictions,Smoluchowski’s theory indicates that equation (1) is applicable tothe electrophoresis of suspended particles of any shape, and also tothe electrosmotic velocity of a liquid in the neighbourhood of asurface to which the applied field is tangential, and that equation (2)is applicable both to capillary tubes and to porous diaphragms.Thonecessary restrictions are given by Smoluchowski, and have beenH. Freundlich and G. V. Slottman, ibid., 1927, 129, 305; H. Mueller,Kolloidchem. Beih., 1928, 26, 257; P. Tuorila, ibid., 1928, 27, 44; A. March,Kolloid-Z., 1928, 45, 97; J. N. Mukherjee and S. P. Rai-Choudhuri, Nature,1928, 122, 960; S. Mattson, Soil Science, 1929, 28, 373; D.R. Briggs, J .Physical Chem., 1930, 34, 1326; S. W. Pennycuick, J., 1930, 1447; H. R.Kruyt, A. C. W. Roodvoets, and P. C. van der Willigen, Colloid SymposiumMonograph, 1926, 304; H. R. Kruyt and D. R. Briggs, Proc. Acad. Sci.Amsterdam, 1929,32, 384; H. R. Kruyt and E. F. de Haan, Kolloid-Z., 1930,51, 61.l8 F. Powis, 2. physikal. Chem., 1915, 89, 186.2O See ref. (75)350 HENRY :discussed in detail by M. MooneyY2l D. C. Henry,22 and E. Manegoldand K. S ~ l f . ~ ~ Following the suggestion of M. G o u ~ , ~ ~ the “ outersheet” of the double layer i s nowadays considered to be, not alaminar distribution of electrification, but a diffuse ionic “ atmos-phere,” producing a continuous rather than a sudden fall of potentialfrom the rigid phase into the liquid.It is not agreed whetherSmoluchowski’s theoretical deduction is applicable to a doublelayer of this type. P. Debye and E. Hiicke125 and E. Hiicke126consider it is not, and replace equation (1) byU / X = CDCjq, . . . . . . . (3)where C is a constqnt depending on the shape of the particle, andhaving the value 1/6x for a sphere. On the other hand, Mooneyand Henry have both shown that Debye and Hiickel’s conclusionsrest on a particular assumption, not generally realised in practice,about the distribution of the applied electric field, and Henryclaims to have shown that for electrically insulating particles ofspherical or cylindrical form and of sufficiently large size, equation(1) holds. Debye and Hiickel’s conclusion that the electrophoreticvelocity of a particle should depend on its shape is supported byD.A.NewtonY27 K. van der GrintenY2* andB. W. Currie ; 29 the first twoauthors quoted, however, assume that the surfaces of broken particlesof a given material will have the same C-potential as surfaces preparedby fusion or polishing, an assumption which H. Abramson30 andD. C. Henry31 claim to be erroneous. By making use of the dis-covery previously referred to, zlix., that particles of glass, quartz, andmany other materials adsorb a layer of protein from dilute solutionand behave electrokinetically as protein, H. Abramson 32 has shownmost conclusively that the electrophoretic velocity of a relativelylarge particle does not depend on its shape, and that equation (1)is generally valid in such cases.This is confirmed for wax sus-pensions by D. C. Henry 33 and for a macroscopic cylindrical surfaceby C. G. Sumner and D. C. Henry.34Equation (1) strictly applies to the motion of a single particle in21 J . Physical Chem., 1931, 36, 331 ; A., 429.22 Proc. Roy. SOC., 1931, [A], 135, 106; A., 1232.23 Kolloid-Z., 1931, 55, 273; A., 905.24 Compt. rend., 1909, 149, 645; J. Physique, 1910, 9, 457; see also 0.Stern, 2. Elektrochem., 1924, 30, 508.z 5 Physikal. Z., 1924, 25, 49.27 Phil. Nag., 1930, [vii], 9, 769 ; A., 1930, 858.28 Compt. rend., 1924,178, 2083; A., 1924, ii, 664.29 Phil. Mug., 1931, [vii], 12, 429; A., 1122.3O J . Physical Chem., 1931, 35, 289 ; A., 429.31 Ref. (22). 32 Ref. (30). 33 Ref. (22).34 Proc.Roy. Soc., 1931, [ A ] , 135, 130; A . , 1233.2G Ibid., p. 204COLLOID CHEMISTRY. 35 1an infinite liquid; a correction to take account of the hydro-dynamical interaction of a multiplicity of particles has recentlybeen published.35Some doubt has now been thrown on the validity of the Helm-holtz-smoluchowski equations from a different direction. N. Thon 36points out that for the electrophoresis of a variety of solid particlesin the presence of electrolytes, the maximum of the <-c curve, whenit occurs, is found at a concentration in the neighbourhood of 1 milli-mol. per litre, and similarly minima occur at about 3 millimols. perlitre. On the other hand, in stream-potential measurements withglass capillaries, the maxima and minima occur at concentrationsroughly a thousand times smaller.This is taken to indicate thatthe " '5" as evaluated by electrophoresis is not the same as thatarrived a t by stream-potential measurements. G. Ettisch andA. Zwanzig37 find that albhough t: (by stream potential) is in-dependent of the applied pressure in aqueous solutions, this isfar from being true in aqueous methyl alcohol, and conclude that < is not a constant independent of the experimental method andconditions employed. E. Manegold and K. Solf 38 find similarlythat the electrosmotic transport through a, membrane filter is notproportional to the current, as required by equation (2), but thatV / J diminishes with increasing J . They attribute this behaviourto alterations in the effective viscosity, spec& conductivity, anddimensions of the electrical double layer, and propound a quantita-tive theory to take account of these factors. It is evident thatdirect comparisons of the principal electrokinetic methods areurgently required; in the only recent investigation of this type,3ga comparison of the electrophoretic and stream-potential methodsapplied to surfaces covered with the same protein indicates that thetwo methods do actually lead to the same value of <, but this needsconfirmation over a wider field.PART III.--COLLOID CHEMISTRY OF CLAYS.By R.K. SCHOFIELD.Base Exchmge.-The discovery of the phenomenon of baseexchange is due to J. T. Way, who found that soil has the powerof removing small quantities of dissolved base, such as ammonia or35 W.0. Kermack, A. G. McKendrick, and E. Ponder, Proc. Roy. SOC.Edin., 1929, 49, 170; A., 1929, 878.36 2. physikal. Chern., 1930, 147, 147; A., 1930, 696.38 Ref. (23).3~3 H. A. Abramson and E. B. Grossman, J . CTm. Physiol., 1931, 14, 563.37 Ref. (6)352 SCHOFIELD :lime, from the solution. He also observed that when a solution ofa salt, such as potassium sulphate, percolates through a soil, someof the potassium sulphate is removed and an equivalent quantify ofcalcium sulphate appears in the solution. He explained thisphenomenon by supposing an amount of lime, which had previouslybeen taken up by the soil, had exchanged with potash ; hence theterm ‘‘ base exchange.” In the light of the electrolytic dissociationtheory, the phenomenon might be called kationic exchange, as itis evident that it is sufficient to suppose that kations only areinvolved ; nevertheless, the older word is still usually employed.The phenomenon is of great importance in agriculture, as itprovides a mechanism by which plant nutrients, which would other-wise be readily washed out of the soil, are retained for the use ofsucceeding crops.The buffer action involved in the phenomenonalso stabilises the pH in the soil, thereby rendering it more equitableas a medium for plant life. A right understanding of the phe-nomenon is proving to be of increasing service in the ceramicindustry, for important changes are brought about in the physicalproperties of clays as a result of quite small changes in the propor-tions of the exchangeable kations.Base exchange is the basis ofthe “ permutit ” water-softening process, which relies on the factthat when present in equal concentrations, calcium ions are takenup by the permutit in preference to sodium. Apart altogether fromthese practical applications, the study of this subject has an importantbearing on general colloidal theory, and it is this aspect which ischiefly emphasised in the following paragraphs.Before discussing in detail the colloid chemistry of clay, it isnecessary to make clear exactly what materials may beconsidered as falling into this category. To the agriculturist, clayconsists of the finely divided mineral constituents of a soil, Origin-ally the division was fixed with respect to a convenient time ofsettling through water, but it was later found that the particleswhich settled through water faster than about 1 cm.an hour usuallyshowed little base exchange activity. This imposes an upper limitto the particle size of about 2 p. In the discussion that followsthe above definition is implied. To the ceramist, the word “ clay ”means rather a material consisting of small laminated particleshaving the firing properties required for pottery work. For thispurpose, a material is used containing particles larger than thoserecognised as agricultural clay, but here again these particles donot contribute appreciably to the base exchange capacity of thematerial.When clay is washed with dilute acid, an exchange occurs betweenthe hydrogen ions and other kations which had previously beeCOLLOID CHEMISTRY.353held by the clay. The material thus produced is generally spokenof as a hydrogen clay, or, sometimes, as an acid clay. The reasonfor specifying that the acid should be dilute is that in strong acid,particularly when hot, kations come into solution as a result of thedecomposition of the clay particles. In support of the view thatno important decomposition occurs with dilute acid may be citedthe experiments of W. P. Kelley and S. M. Brown,l S. Mattson,2and B. D. JVik~n,~ which show that the same quantities of exchange-able base are removed by N/ZO-hydrochloric acid as by N-ammoniumchloride or by electrodialysis of the clay. At the same time, it wasfound that the dilute acid removed small quantities of silica andsesquioxides-rather more than the electrodialysis-while prac-tically none was removed by N-ammonium chloride.Even withdilute acid, the amount (reckoned in equivalents) is only a fewunits % of the exchangeable bases.The view that hydrogen clay is a colloidal acid has been supportedby a number of lines of evidence. F. E. Rice and S. Osugi * studiedthe rate of inversion of cane sugar in soil suspensions. Theyshowed that inversion only took place in the presence of the soil,not in the water extract, and, further, that its rate was proportionalto the quantity of the soil used. They interpreted this inversionas being caused by the acidity of the soil, stating that these soilacids are not soluble in water and therefore cannot be removed bywater extraction.confirmed theresult that th.e acidity of an acid soil suspension increases with theconcentration of the soil as measured by the rate of inversion ofsucrose, and also by the hydrogen electrode, but they showed thatthe proportionality between the hydrogen-ion concentration andthe soil concentration only held over a limited range. R. Bradfield,Gusing electrodialysed colloidal clays, compared the variation of thepH of the clay concentration with that obtained on dilution ofacetic acid, and argued from the similarity of the two curves thatthe clay should be regarded as a weak colloidal acid. This pointhas been investigated in great detail by G. Wiegner and H.Pall-mann ' in a series of papers, who showed quite generally for an acidcolloidal system that an electrode can be affected by hydrogen ionsR. M. Salter and M. F. MorganUniv. of Calif. Agric. Expt. Station of Coll. of Agmc., 1924, Tech. Paper,J . Agric. Res., 1926, 33, 663.Ibi&., 1918,5, 333.(I Ibid., 1924, 28, 170.7 Verhdl. 11. Komm. Intern. Bodenkunde Gesell. Budapest, Teil B., 1929, 92;Z. PfEanz. Dung., 1930, [ A ] , 1 6 , l ; Ergeb. Agrik.-chem., 11, 1-37 ; G. Wiegner,Kolloid-Z., 1930, 51, 49; J . SOC. Chem. Id., 1931, 50, 10311; H. Pallmann,Kolloidchem. Beih., 1930, SO, 334.REP.-VOL. XXVIlI. MNo. 16.Soil Sci., 1928, 26, 407.J . Physical Chem., 1923, 27, 117354 SCHOFIELD :dissociated from the colloidal particle, so that, if a hydrogen clayis dispersed in pure water, the acidity increases as the concentrationof the clay increases, and, in fact, the increase in hydrogen-ionconcentration is proportional to the concentration of the colloidalsol provided the clay concentration be not too large.Further, ifa salt such as sodium chloride is added to the clay, the dispersionmedium becomes more acid, but the acidity of the clay is decreased,that is, the effect of increasing the concentration of the clay on thehydrogen-ion concentration of the sol was decreased. They showedthese results were not mere electrode effects by checking thepotentiometer measurements of the hydrogen-ion concentrationagainst measurements on the rate of inversion of cane sugar ; andfurther, that for a deflocculated colloidal system both methodsgave almost exactly the same value for the hydrogen-ion concen-tration, while for a flocculated system the sugar inversion gave ahigher value than the potentiometric, which was interpreted as dueto the sugar molecules being able to get inside the loose flocculesand to be inverted there, while the electrode was unaffected by theselocked-up hydrogen ions.These experiments provide strongevidence that the particles of an acid clay are surrounded by aswarm of hydrogen ions which can be displaced by other kations.The clay shows all the properties of a true colloidal acid, as described,e.g., by L. Michaefis.8A suspension of hydrogen clay may be titrated potentiometricallyagainst an alkali by using a hydrogen electrode or, in the lowerpH range, a quinhydrone electrode, and the curve so obtained bearsat least a superficial resemblance to that for a weak acid.Thoseworkers who have been reluctant to accept the colloidal acid theoryhave stressed the fact, first ascertained by Bradfield, that the positionof the titration curve with sodium hydroxide differs considerably fromthat obtained with baryta. It might be urged that this difference,although somewhat larger than that obtained with, say, phosphoricacid, is, nevertheless, of the same nature. A striking fact was laterpointed out by H. B. O a k l e ~ , ~ vix., that if titrations are carried outin the presence of an NI2-solution of the chloride of the same metal,the curves for the different alkalis are all superimposed, providedthe p H do not exceed 9.In other words, the clay will take up adefinite amount of base and reach a definite pH for a given additionof hydroxide when the added kation is sodium, potassium, calcium,or barium. Although Oakley did not emphasise the fact, this resultis in reality very singular. For, in the case of simple weak acids,Colloid Symposium Monograph, 1925, 2, 1 ; “ The Effect of Ions in Col-loidal Systems,” Williams & Wilkins Co., Baltimore.13 J . , 1927, 2819COLLOID CHEMISTRY. 355the titration curves with different bases become more nearly coin-cident the weaker the solutions, and become increasingly moredivergent with the addition of neutral salts, whereas the reverse istrue of clays.Nevertheless, there is no doubt about the fact, ofwhich use is made in the measurement of soil acidity. In the caseof an aqueous soil suspension the pH varies considerably accordingto the season, being influenced by the concentration of salts in thesoil solution. The addition of potassium chloride to the solutionreduces the pH, and gives a value which is much more stable andpractically uninfluenced by seasonal conditions.The instability of a clay particle in a medium of pH greater than 9has made it f i c u l t to decide whether or not there is a definitenumber of equivalents of exchangeable hydrogen associated witha given weight of clay. At high p H ’ S in the presence of the alkalikations soluble aluminates and silicates are formed, while with thealkaline-earth kations it is probable that aluminates and silicatesare still formed, but, being insoluble, form a layer over the clayparticles.Both the method of R. Bradfield,lo in which hydrogenclay is added to a strong base, and also that of D. J. Hissink,ll inwhich a soil is placed in excess baryta, and the amount not taken updetermined either by simple or conductimetric titration, are opento objection on this ground. The difficulty in finding an end-pointin the titration of a hydrogen clay with an alkali has led someworkers to advocate the theory that the process involved is one ofadsorption in which both the hydroxyl ions and the kations aretaken up. In support of this view, S. Mattson l2 quotes an experi-ment showing that when a hydrogen clay is treated with calciumhydroxide, the gain in weight of the oven-dried clay corresponds toan adsorption of calcium hydroxide and not to a replacement ofhydrogen ions by calcium ions.Such an experiment cannot,however, be regarded as having any direct bearing on the questionas to whether or not a hydrogen clay in water is a colloidal acid.Whether or not the dried clay is an anhydride of the acid, andwhether the dried calcium clay is a hydrate, are obviously irrelevantto the point at issue. The problem is very similar to that of decidingwhether carbonic acid exists in solution or whether the bicarbonateion is formed by a direct union of the hydroxyl ion with carbondioxide.Permutik-A considerable proportion of the work that has beencarried out on base exchange in permutits was published beforemany of the properties of the hydrogen clay outlined above came tolo J .Amer. Chem. Soc., 1923, 45, 2669.l1 2. PJEanz. Dung., 1926, [A], 4, 137.12 soil sci., 1928, s, 289356 SCHOFIELD :light. At this time it was also supposed that the laws governingbase exchange in permutits could be applied directly to clays.While there is undoubtedly a great similarity between the behaviourof permutits and zeolites on the one hand, and clays on the other,important differences nevertheless exist. As instances of suchdifferences may be cited the difference in speed a t which equili-brium is reached in the two systems. J. T. Way initially showedthat for clays this is attained almost instantaneously, while withpermutits it may take many hours.G. Wiegner l3 has interpretedthis result as showing that, whereas base exchange in clays is anexternal surface phenomenon, that in permutits takes place insidefine capillaries. This idea is supported by the fact that a largekation, such as methylene-blue, can quantitatively displace all theexchangeable base from a clay, but is not taken up appreciably bya permutit. In the case of zeolites, it is usually considered that theexchangeable ions occupy positions in the crystal lattice itself, andthat exchange in this case occurs by a movement of the ions throughthe crystal.Various attempts have been made to formulate quantitative lawsconnecting the equilibrium concentration of ions in the solution withthose held by the permutit. It has been found that, using a per-mutit containing only one kind of kation and a chloride of thealkali and the alkaline-earth metals, the amount of exchange dependsonly on the total amount of permutit and salt present, and not onthe actual concentration of the salt, that is, the exchange is inde-pendent of the amount of water present.l* As to the relationbetween the amount of salt added and the amount of kationsexchanged, two distinct methods of attack have been used : theempirical method, which uses Freundlich’s adsorption isotherm,and a semi-theoretical method, which employs the law of massaction to give some kind of theoretical justification to the formulaproposed. The Preundlich isotherm gives a tolerably accuraterepresentation of the effect of the quantity of added salt on thetotal exchange taking p l a ~ e .1 ~ The Freundlich equation statesthat, if the quantity of permutit, or clay, remains constant(a - c ) = kcup,where a is the initial concentration of the added kation, c itsJ. SOC. Chem. Id., 1931,50,65~.1 4 R. Ganssen, Jahrb. der Kgl. preuss. geolog. Landesanst. u. Bergakad., 1906,26, 179; 27, 63; V. Rothmund and G. Kornfeld, 2. anorg. Chem., 1918,103,129; 108, 216; G. Wiegner and K. W. Miiller, 2. PJanz. Dung., 1929, [A],14,321.16 G. Wiegner and H. Jenny, Kolloid-Z., 1027, 42, 268; G. Wiegner, J .Landw,, 1912,60, 111, 192; H. Jenny, Kolloidcliem. Beih., 1927,23,428COLLOID CHEMISTRY. 357equilibrium concentration, and k and l / p are constants.equation can be rewritten aswhere x is the amount of the added kation adsorbed by the substrateand in this form is seen to be independent of the actual concentra-tions.It suffers from the weakness that it allows of no upper limitfor x, which must in reality exist. But over the range of concen-trations usually employed it gives a very fair representation of theexchange.The second method, based on the law of mass action, has beendeveloped in two forms. The developed by V. Rothmundand (Frl.) G. Kornfeld and based on the ordinary mass-actionlaw in solution, isThisx = k"c/(a - C)]VP' . . . . * (1)where [B,] is the concentration of kation 1, [B,] that of kation 2,and [ ] solution refers to the concentration of the kation in thesolution, while [ 3 clay refers to the amount of the kation adsorbedper g.of clay, and K and n are constants. Anderegg and Lutz, andindependently Kerr, claimed that for soils n = 1 if [B,] and [B,]have the same valency, but Kerr claims to have shown that if [B,]and [B,] have different valencies the formula should be[B1I2 clay = K([Bl]2 solution)CB21 clay [B,] solutionwhere [B,] is a univalent and [B,] a bivalent kation, and from thisresult concludes that clay behaves as a monobasic acid. Thisformula is not independent of concentration, so appears to be incontradiction to Wiegner and Muller's results for permutits, inwhich they showed that, even if the valencies of the two kationsdiffer, their equilibrium distribution is independent of the actualamount of water present.This contradiction needs furtherinvestigation.The second form developed by Langmuir for adsorption a t aninterface, and independently by P. W. E. Vageler l7 as an empiricalequation, iswhere y is the quantity of the base adsorbed, and z the amount ofthe base in equilibrium with the substrate (Vageler first assumed zl6 R. Gans, Centr. Min., 1913, 699, 728; V. Rothmund and G. Kornfeld,Ref. (14); F. 0. Anderegg and R. P. Lutz, Soil Sci., 1927, 24, 403; H. W.Kerr, J . Amr. SOC. Agron., 1928, 20, 309; Soil Sci., 1928, 28, 385.1 7 Landbouw. (Java), 1928, No. 6,244; P. W. E. Vageler and J. Woltersdorf,2. PJEanz. Dung., 1930, [A], 15,329.Y = SxlV + 358 SCHOFIELDwas the amount of base added), X is the maximum exchange capacityfor the substrate, and C is a constant. No critical comparative studieson the relative efficiencies of these three equations have been made.A comparison of the replacing power of different kations has beenworked out in considerable detail for permutits,18 but not so exten-sively for ~ 1 a y s .l ~ For a clay, or permutit, saturated with a givenbase, the lithium kation is the weakest replacer of the adsorbedbase, and sodium, potassium, rubidium, and czesium follow in order ;finally comes hydrogen, which is the strongest replacer. For per-mutits, and probably for clays, though this point has not beenproperly confirmed, a given concentration of a definite kation candisplace more lithium from a lithium permutit than sodium froman equivalent amount of sodium permutit, and so on.For thealkaline earths, magnesium is the weakest replacer, followed inorder by calcium, strontium, and barium; but, unlike the case ofthe alkali metals, a given concentration of a definite kation displacesmore barium than calcium and more calcium than magnesium.This result holds for both clays and permutits. The explanationoffered by Wiegner and Jenny for this anomaly is that the ions areheld to the permutit by hydroxyl bindings, and, since magnesiumhydroxide is more insoluble than calcium hydroxide, the magnesiumis assumed to be more tightly bound to the permutit surface than isthe calcium., Similarly, for strontium and barium.Wiegner and Jenny, working with permutits, expressed theirexperimental results by fitting to them equations of the form (1).They found that 1/p’ depended mainly on the valency of theadsorbed and added kations, and the constant of proportionalitydepended both on the kation initially present in the permutit andon the exchanging kation.For a permutit containing a given base,k’ was smallest when lithium was the added kation, and increasedsteadily to czesium for the alkali kations, and was smallest whenmagnesium and largest when barium was the added kation for thealkaline-earth kations. Further, the constant k’ appeared to beproportional to the true ionic volume of the ion, i . e . , its volumededuced from X-ray crystallographic data. Wiegner and Jennyinterpreted these results on the ionic hydration theory, namely,that for an ion of a given valency the smaller its radius the morestrongly it is hydrated, and therefore the larger its effective volume.Thus, the lithium ion, being heavily hydrated, is effectively largerthan the cssium ion.As further evidence in favour of the hydrationhypothesis it was shown 2o that, if the base exchange was carried out18 H. Jenny, ref. (16); G. Wiegner and H. Jenny, ref. (16).19 K. K. Gedroiz, J. Exp. Agron. (Russ.), 1918,19, 269; 20, 31.20 Wiegner and Jenny, ref. (16)COLLOID CHEMISTRY. 359in alcoholic solution, not only was the amount of exchange increased,but the relative order of the ions was altered, and, in fact, in an80% alcoholic solution potassium was more strongly adsorbed thanwas cEsium or sodium, which are equally strongly adsorbed, so that,as the alkali ions become dehydrated the relative difference inreplacing power between them becomes more nearly equal. Wiegnerand Muller 21 tried to see how far a simple reduction of the dielectricconstant of the dispersion medium would explain the increasedexchange due to dehydration, and investigated the effect on theexchange of two sugars, vix., glucose, which reduced the dielectricconstant of the water very considerably, and cane sugar, whichaffected it but little. They found that neither sugar had anyappreciable effect, and explained this by assuming that the surfaceson which base exchange takes place in a permutit are situated inpores, whose size is such that sugar molecules are too large to enter,but alcohol molecules are small enough to do so.In confirmationof this explanation, Wiegner l3 has shown that tri- and tetra-methyl-ammonium ions are barely adsorbed by permutits, whilst even themonomethylammonium ions are adsorbed less strongly than theammonium. Thus the pore size in permutits seems to be such asto allow alcohol and ammonium ions and even, to a certain extent,monomethylammonium ions to enter, but to be too fine to giveaccess to larger ions.In considering the external influences which might affect baseexchange, Wiegner l5 studied the effect of temperature and foundthat it exerted no appreciable influence between 0" and 50". Theeffect of the anions has been studied by A. Baumann and U.Gully,22E. Ungerer,23 and A. N. P ~ r i , ~ ~ whose results bear out the view thatthe anions influence the phenomenon only in so far as they affectthe activity of the kations and the hydrogen-ion concentration.Flocculation Phenomena.-When soil is shaken with about 100times its weight of dilute (say 0.1%) sodium carbonate solution, thesuspension does not clear if allowed to stand for weeks or even foryears. It is only necessary to add a small quantity of acid (slightlymore than sufficient to neutralise the carbonate) to cause all thesuspended material to settle, leaving a clear supernatant liquid.The first condition is usually spoken of as deflocculated : the secondas flocculated. In the deflocculated condition the soil particles areseparately dispersed, and the smallest of them can be seen underthe ultramicroscope to execute Brownian movement.To obtainthe size distribution curve by observation of the rate of settling, a21 Ref. (14).23 2. PJlanz. Dung., 1930, [ A ] , 18,342.24 Mem. Dept. Agric. India, 1930.11, 1.22 Mitt. kgl. bayr. Moorkulturanstalt, 1910, 4, 39360 SCHOFIELD :soil is always brought into the deflocculated condition by the additionof ammonia, sodium carbonate, or sodium hydroxide according tothe method employed. P. Tuorila25 has followed the transitionfrom the flocculated to the deflocculated condition in the case ofclay suspensions, about 0.1 yo by weight, which are sufficiently diluteto be studied in the ultramicroscope. The suspensions used wereapproximately monodisperse, i e ., all the suspended particles wereof approximately the same size. When more than a critical amountof flocculant has been added to such a system, coagulation proceedsat a rate which follows the Smoluchowski equation for rapid coagul-ation, i.e., the rate of decrease of the particle numbers depends onlyon the initial number of particles present in unit volume, and is notincreased by further additions of the flocculant or influenced by itsnature, provided that it be either a neutral salt or a dilute acid.The conclusion to be drawn from this result is that, under rapidcoagulation, the encounters between the clay particles are broughtabout solely, or a t any rate mainly, by their Brownian movement,and that two particles once having come together remain together,When less than the critical amount of flocculant has been added,coagulation proceeds at a slower rate, but does not in general followthe Smoluchowski equation for slow coagulation, which supposesthat only a certain constant fraction of the encounters of the par-ticles leads to their adhering, the fraction increasing with theamount of flocculant added.According to this equation, thereciprocal of the particle numbers should increase linearly with thetime. Tuorila showed that, with a clay suspension, the rate ofincrease of 1/N falls off with the time, Le., the particle numbers donot diminish as rapidly as one would expect from the Smoluchowskitheory. Tuorila was inclined to attribute this discrepancy to a lackof uniformity in the size of the clay particles, resulting in a variationof the electrokinetic potentials.An alternative explanation is thatthe secondary particles do not remain stable under collision, asassumed by Smoluchowski, but that there is a certain probabilityof their partial break up. This suggestion is made more plausibleby the fact that a flocculated clay suspension is readily redispersedif sufficiently diluted.A further case has been investigated by Wiegner 26 and Tuorila 27in which collisions between particles are brought about by sedi-mentation of some particles relative to others in the suspension.Provided a sufficient electrolyte concentration be present , theyshowed that this mechanism was sufficient t o account for the decreasein particle numbers in such a system.Much of the earlier work on26 2. Pjlanz. Dung., 1928, [A], 11, 1 6. 25 Kolloidchem. Beih., 1928,27,44.37 Holloidchem. Beih., 1927, 24, 1COLLOID CHEMISTRY. 361the flocculation of soil suspensions has been complicated by the factthat these two mechanisms have not been separated.The majority of agricultural clays, when freed from solubleelectrolytes, are readily dispersed in water and remain deflocculant .Several workers have determined the quantity of a neutral salt whichmust be added to produce a recognisable stage of flocculation. Muchof the earlier work gave conflicting results because insufficientaccount was taken of the influence of the exchangeable base in theclay. This point is illustrated by the curve (Fig.4), which givesFIU. 4. . 4Milli-equivs. of NaOH added to the hydrogen clay.the concentration of sodium chloride required to produce a definitedegree of flocculation in clays containing increasing amounts ofexchangeable sodium, these clays being prepared by adding increas-ing amounts of sodium hydroxide to hydrogen clay. Measurementsof this kind have been made by R. Bradfield,28 and A. I?. Josephand H. B. O a k l e ~ . ~ ~ The sigmoid shape of the curve accounts forthe " anomalous flocculation " discovered by Oakley,30 for, on theaddition to a hydrogen clay of a mixture of sodium chloride andsodium hydroxide, corresponding to the straight line OA on thediagram, flocculation first occurs at P, deflocculation at &, and theclay again flocculates at R.It is evident that only mixtures repre-28 3. Amer. SOC. Agrm., 1925,17, 253. a* Nature, 1926, 117, 624.Ibid., 118,661.M 362 SCHOFIELD :sented by lines falling between Oh' and OC will give rise to thisphenomenon. I n discussing the flocculating action of neutralsalt's, it is important to distinguish cases, such as the above, in whichthe kation of the salt is the same as that combined with the clay,and the more general one where this is not the case and where theconditions will be complicated by base exchange. In the specialcase where a neutral salt is added to a hydrogen clay, the complicationfrom this cause is not very great, since unless an alkali or a salt ofa weak acid is present, little of the hydrogen will exchange with theadded katioii.K. I<. Gedroiz 31 showed that the flocculating powerof kations increases with their valency, which is in accordance withthe Hardy-Schulze valency rule. 'Tuorila 32 gives evidence to showthat the rate of coagulation is closely connected with the electro-kinetic potential as determined by their cataphoretic mobility.The results are the same for the kations in a given valency class,but are found to depend somewhat on the valency.M. S. Anderson,33 S. M a t t ~ o n , ~ ~ and L. D. Eaver 35 have shownthat suspensions of clays containing a bivalent alkaline-earth kation(magnesium, calcium, strontium, barium) are less stable and havea lower electrokinetic potential in the absence of electrolytes thanclays containing a univalent alkali kation (lithium, sodium, potass-ium) or hydrogen, as is shown in Table I.As may be seen,TABLE I .Mean electrokinetic potential of clays relative to the calcium clay.Anderson. Mattson. Baver.Ca-clay ..................... 100 100 100Mg-clay .................. 99 - 110K-clay ..................... 134 - 164Na-clay .................. 149 191 169H-clay ..................... 23 168 128Anderson found that a hydrogen clay has a lower electrokineticpotential than the corresponding calcium clay, but this result hasnot been confirmed by other workers. Mattson, however, madethe interesting observation that electrolytes depress the electro-kinetic potential of a hydrogen clay much more rapidly than acalcium clay, and, in fact, it does not require a large electrolyteconcentration to give the hydrogen clay a lower electrokineticpotential than the calcium clay.If clays containing an alkali kationare considered, the more hydrated the kation, or the lower its atomic31 Bureau of Agric. and Soil Sci., Scientific Communications of Dept. of(Used only Land Organisation and Agric., Petrograd, 1915, Comm. No. 24.in the English translation issued by U.S. Dept. of Agric., 1923.)32 Kolloidchem. Beih., 1928, 27, 44.33 J . Agric. Res., 1929, 38, 565.a 5 Missouri Expt. Sta. Res. Bull. No. 129, 1939.34 Soil Sci., 1929, 28, 373COLLOID UHEMISTRY. 363weight, the higher is the electrokinetic potential of the pure claysuspension, and the more stable it is. Mattson further showed thatif the theory of the critical potential is valid for clay suspensions,then this potential depends on the exchangeable ion present.Forinstance, he calculated a critical potential of - 55 millivolts for asodium clay, whereas that for the corresponding calcium clay wasonly - 22 millivolts.These results throw much light on an apparent anomaly in thebehaviour of many colloidal suspensions. In general, if an elec-trolyte is added to an electronegative sol its electrokinetic potentialis depressed, unless the electrolyte is a sodium or potassium salt,in which case it often rises a little before falling. Mattson, forexample, found that if potassium chloride is added to a calcium claysuspension, the electrokinetic potential first rises a little beforefalling, but if it is added to a sodium clay suspension the electro-kinetic potential falls continuously. This anomaly is probably dueto secondary effects consequent upon base exchange.When potassium chloride is added to a calcium clay suspension,a certain amount of calcium will be exchanged for potassium,giving a clay containing both adsorbed calcium and adsorbedpotassium.The introduction of potassium into this system raisesits electrokinetic potential, and if this rise more than counterbalancesthe depressing effect of the added electrolyte, the electrokineticpotential of the clay particles rises. But if the clay is a sodiumclay, the exchange of potassium into the complex with sodium willdepress the electrokinetic potential of the clay particles, so botheffects reduce the potential.Anderson and Mattson 36 showed that the higher the ratio of silicato sesquioxides in a clay, or the higher its exchange capacity, thehigher is the electrokinetic potential of the clay suspension whencontaining a given kation, in the absence of added electrolyte, andthe more stable is this suspension.Mattson 34 considered that thiseffect pointed to a greater hydration of a clay with the high exchangecapacity. He showed that if clays were dehydrated by using 75%alcohol as the dispersion medium, the concentration of added elec-trolyte is more nearly the same for different clays, as Table 11, takenfrom his paper, shows.The exchange capacity for Sharkey and for Norfolk clay is respec-tively 0.796 and 0.207 milli-equiv.per g.In general, when a very dilute clay suspension coagulates it neverclears completely unless centrifuged, and the complex particles areeither not visible or barely visible to the naked eye. A charac-teristic of the coagulation of clay suspensions in alkaline media isa6 U.S. Dept. of Agric. Bull. No. 1452, 1926364 SCHOFIELD :that large loose aggregates, or flocs, are formccl, which settle rApidly,leaving a clear dispersion medium, and that this flocculation isseveral times more rapid than the usual rapid coagulation in aneutral medium. Thus, Brownian movement cannot be the onlyagent bringing about encounters between the particles. The earlyinvestigators who studied this effect explicitly, e.g., N.M.M a t t s ~ n , ~ ~ and F. Hardy,39 only studied the effect in the presenceof calcium salts, but it was not until Tuorila40 investigated thcinfluence of other kations that a critical discussion of this effectcould be undertaken. He showed that the possibility of the form-ation of a weakly soluble salt was an essential part of the pheno-TABLE 11.Concentration of electrolyte required to coagulate a clay suspension inaqueous and in alcoholic solution.Dispersion NaCl coagulating an KCl coagulatingmedium. Clay. Na-clay. a K-clay.0.08 0-030.004 0-003 Water {g?;;~75% Alcohol { :!:% 0.0010.0010-00050*0003menon. Tuorila showed that if sodium hydroxide is added to aclay suspension containing the chloride of a bivalent metal in solu-tion, the more insoluble the hydroxide of this metal the lower is theconcentration of the chloride required to bring about this abnormallyrapid flocculation. He further showed that, whenever this floccul-ation takes place, the conditions are such that if any colloidalparticles of the hydroxide were formed in the suspension they wouldbe electropositive and, therefore, of opposite charge to the clayparticles.If such a hydroxide suspension is mixed with a claysuspension an extremely rapid and analogous flocculation sets in.The course of this flocculation was followed under the ultra-microscope, and it was shown that the rate of decrease of particlenumbers is much greater than is given by the Smoluchowski theoryfor rapid coagulation of monodisperse systems of spherical particles.The quantity Alp, the ratio of the attractional radius of a particleto its hydrodynamical radius, was as high as 70 after coagulationhad been proceeding for 90 seconds, had fallen to 20 after 6 minutes,and after 2 hours had only fallen to 4, while for the same claysuspension coagulating in a neutral medium A/p was about 2, socollisions between particles are evidently caused, not only by theirBrownian motion, but also by the attractional forces between them.37 J .Agric. Sci., 1920, 10, 425; 1921, 11, 450; 1922, 12, 372.30 Kolloidchem. Beih., 1922,14,227.s9 J . Physical Chern., 1926, 30, 254. 40 Ref. (26)COLLOID CHEMISTRY. 365R. K. Schofield and G. W. Scott Blair 41 have measured the depthof the sediment of flocculated clay thrown down from suspensionsof clay containing different exchangeable ions by varying theamounts of the corresponding chlorides, and have also made relativemeasurements of the strength of the rigid structure of the sediments.They found that the substitution of calcium for some of theexchangeable hydrogen does not affect the sediment volume, nor isthis influenced by the concentration of calcium chloride and bariumchloride until these reach normality of about N = 1. When theclay contains exchangeable sodium or potassium ions, high con-centrations of the corresponding chlorides are required to flocculatethe clay. In these cases, and whenever the clay is suspended in achloride of about N-concentration or above, a thixotropic gel oflarger volume is formed. The strength of the rigid structure of thesediment depends on the exchangeable ions present and on thenature and concentration of the added salt. The relationshipsinvolved appear to be complex. The reproducibility of the sedimentvolume obtained in dilute salt solutions suggests that a measurementof this quantity may be of use in soil studies.The distinction between a flocculated and a deflocculated claysuspension persists even when the suspension is relatively concen-trated. Just as the condition of many colloids in suspensions isjudged by their viscosity, so observations on the flow propertiesof clay suspensions may be used in studying this distinction. Theproblem is, however, complicated by the fact that clay suspensionsdo not obey Poiseuille's law, except a t great dilution, and conse-quently the flow properties of the more concentrated pastes cannotbe represented by a single constant. R. E. Wilson and IF. P.following E. C. Bingham,43 showed that the graph connecting therate of flow and applied pressure is linear except for low pressuresbut that the linear portion when extrapolated does not pass throughthe origin but makes a positive intercept on the pressure axis.The flow at high pressures can therefore be expressed by twoconstants, one representing a stress and measured by the intercept,and the other analogous to viscosity which can be calculated fromthe slope (sometimes termed pseudo-viscosity). M. SirnonisJu andlater, W. L. Shearer 45 and others, studied the influence of flocculantsand deflocculants on these properties. In general, .a paste shows ahigher intercept and a higher pseudo-viscosity when flocculated41 Tram. Paraday SOC., 1931, 27, 629.42 J . 1n.d. Eng. Chem., 1922,14,1120.43 " Fluidity and Plasticity " (McGraw-Hill Book Co.), 1922; and earlier44 Sprechsaal, 1905, 38, 697, 881, 1625; 1906, 39, 1167, 1184.O5 J . Amer. Ceram. Soc., 1928,11, 542.papers366 COLLOID CHEMISTRY.than when deflocculated. Use is made by ceramists of this fact inadding sodium silicate and similar deflocculants to the casting slip.When deflocculated, the clay will pour at a low water content, andhence a minimum amount of water has to be extracted by thecasting to produce a hard body. G. W. Scott Blair and E. M.Cr~wther,~s and later, Schofield and Scott Blair,47 have studied thecharacteristics of the flow of clay pastes in considerable detail, andhave demonstrated the great complexity of the system. An accountof these studies is outside the scope of this Report.The phenomenon of deflocculation is met with in “ alkali ” soils.48Where, as is frequently the case, the condition has been broughtabout by the accumulation of sodium salts in the soil, no deterior-ation in the physical condition occurs while the salt content remainsabove a certain critical amount. The reduction of the salt con-centration below this value, however, brings about a completechange which, by analogy with the behaviour of the dilute sus-pensions discussed earlier in this report, is recognised as defloccul-ation. The soil, although wet and sticky, allows water to percolateonly very slowly. The presence of soluble calcium salts in sufficientquantity prevents this deflocculation. I n reclamation work, calciumsulphate, and sometimes calcium chloride, are spread over thesurface before irrigating, or, if the soil contains calcium carbonate,a salt resistant crop is grown and ploughed under, using only asmall amount of water. The carbon dioxide thereby evolvedbrings sufficient calcium bicarbonate in solution.46 J . Physical Chem., 1929, 33, 321.4 7 Ibid., 1930, 34, 248; 1931, 35, 1212; G. W. Scott Blair, ibd., p. 374;48 ( S i r ) E. J. Russell, “ Soil Conditions and Plant Growth,” Sixth Edition,#oil Sci., 1931, 31, 291.1932, Chap. 4 (Longmans)

ISSN:0365-6217    

DOI:10.1039/AR9312800322

出版商:RSC    

年代:1931

数据来源: RSC

摘要:

THE STRUCTURE OF SIMPLE MOLECULESI. METHODS.THE last few years have seen the development of a variety of quitedistinct methods of physical investigation, throwing light on thedetails of molecular structure ; so that it is now possible to elucidatethe structure of covalent molecules by the converging results of aseries of independent physical arguments. These methods areapplicable in principle to complex as well as simple molecules, buttheir results are naturally more easily interpreted in the simpler cases.The application of wave-mechanics to the sharing of electrons hasbeen greatly extended in the last two years ; of special interest forthe subjects here discussed are the work of E. Hiickel,2 giving atheoretical basis for the absence of free rotation of doubly linkedatoms, and two recent papers by L.Pauling ; in the first of these hecalculates the valency angles, and finds that while in a 4-covalentatom they should normally have the tetrahedral value of 109-5",with atoms of covalencies of 2 or 3 the angles are approximately 90".Another important conclusion is that bivalent nickel, palladium, andplatinum and other transitional elements should form 4-covalentcompounds in which attached groups occupy the corners of a squarewith the metallic atom at its centre.4 W. Heisenberg has, however,pointed out that the basis of these calculations, which is also thatof the work of Heitler and London, is not quite certain. Pauling'ssecond paper deals with the conditions under which links of one andof three electrons are possible.The number of properties of a molecule which can be investigated,and which are of greater or less value for the determination ofstructure, is very large.In this Report only a fe,w of the moreimportant will be discussed; these are the distances between thelinked atoms, the force constants of the links (the forces required tomove the atoms further apart or nearer together), the mean restoringforces during vibration, the energy involved when the atoms formthe link, the angles between the valencies, and the dipole momentsof the links, which express the ratio in which the linking electronsare shared between the atoms.1 See Ann. Reports, 1930, 27, 10.3 J . Amel.. Chem. SOC., 1931, 53, 1367, 3225.4 Seep. 399.5 '' Chemistry at the Centenary (1931) Meeting of the British Association."2 2.Elektrochem., 1930, 36, 641.See also J. C. Slater, PhysicalRev., 1931, 37, 481368 SIDGWICE AND BOWEN :The experimental methods concerned involve the use of radiationsfrom the far infra-red down to X-rays, and, recently, electron waves ;the measurement of the heat properties; and the determination ofdielectric constants. Since the same information is often given byvery different methods, it is convenient to discuss the methods firstand the results later.Spectroscopic Methods.Molecules can absorb or emit energy in three ways : (1) by thechange of an electron from one orbit to another, (2) by a change ofthe oscillational or vibrational energy of the atoms, and (3) by achange in the rotational energy.The energies concerned can beexpressed in caIories per gram-molecule, in “volts,” or more correctlyelectron volts (the unit being the energy gained by an electron infalling through a potential drop of one volt), or in terms of thewave-length, wave-number, or frequency of the radiation emittedor absorbed. The following table gives an idea of the magnitude ofthe three kinds of quanta concerned.Energy. Separation7- in band ofKilocals./ Wave-length, Wave-number, 6000 A.,Transition. Volts. g.-mol. A. cm.-’. A.Rotational +aTB 0.023 1235 x lo4 8.1 3Electronic 1-10 23-230 12,350-1,235 8,100-81,000 (6000)Oscillational or & 2.3 123,500 810 300vibrationalor 1235por 0-1235 cm.The methods may be classified according to the region of thespectrum examined.Far Infra-red Absorption Spectru of Gases. 6-Molecules possessingan electric moment can absorb far infra-red radiation by an increaseof rotational energy (m+ m + 1).Hence a diatomic molecule(with one degree of freedom) gives an absorption spectrum in thisregion of almost equally spaced lines, the frequencies of which wereshown by Heisenberg to be :v = mh/4x2Jwhere m is an integer, and J is the moment of inertia of the molecule.Since we know the masses of the atoms, this enables us to measure r,the distance between the nuclei, from the relation :J = M1M2 x 1.65 x r2 g.-cm.2MI + M2where M , and M , are the gram-atomic weights of the atoms.Berlin, 1930),ThisSee “Das Ultrarote Spektrum,” C.Schaefer und F. Matossi (SpringerTHE STRUCTURE OP SIMPLE MOLECULES. 369method has been applied, for example, to determine the interatomicdistances in the hydrogen halides.'In principle, this method can be applied to more complex mole-cules which give several different moments of inertia. The experi-mental technique of this region (23-200 p) is, however, particularlydifficult, from the feebleness of the radiation obtainable, the lackof transparent materials for the construction of cells and prisms, andthe overlapping of different spectral orders consequent on thenecessity of using gratings for a range of frequencies of manyoctaves. Hence most investigators of infra-red spectra have con-tented themselves with the somewhat easier technique of the nearinfra-red region.Near Infra-red Absorption Spectra.-When the electric moment ofa molecule is changed by the absorption of a quantum of vibrationalenergy, that molecule is capable of absorbing near infra-red radiation,and passing from one vibrational state (almost always n .= 0) toanother (n = 1,2,3, etc.).Such a transition is coupled with changesin the rotational state of the molecule, leading to an absorption bandcomposed of lines given by the relation :The usual rotational changes are rn+ m + 1 (P branch) andm --+ m - 1 (R branch) ; in special cases the Q branch (Am = 0)is observed. These rotation-vibration spectra are investigated, bythe use of a source such as a Nernst glower, an absorption cell withsuitable transparent ends, mirrors to focus the radiation, a prism ofrock-salt or sylvine, generally combined with a grating, to disperseit, and a thermopile to record the transmission.Diatomic molecules such as the hydrogen halides show a simpleseries of absorption bands corresponding to the vibrational tran-sitions 0- 1, 2, etc., each with a rotational fine structure fromwhich values of J , and so of r, can be obtained for the molecule in itsnon-vibrating state and for the molecule with one or more vibrationalquanta. As would be expected, the values of r increase with thevibrational energy of the molecule.The spectra obtained from polyatomic molecules are naturallyvery complex, owing to the interpenetration of bands correspondingto different transitions, and the greatest interest centres at presentround triatomic molecules such as H,O.The results so far obtainedmust be regarded as provisional until the identscation of thefrequencies observed with particular transitions is more definitely7 M. Caemy, 2. Phy~ilc, 1923,16,321; 1925,34,227; 1927, 235; 45,476370 SIDGWICK AND BOWEN :established. When correct identifications are made, the structureof a simple molecule can be deduced from considerations of twokinds.(a) From the number of moments of inertia of the molecule, givenby the fine structure of the infra-red bands. A linear triatomicmolecule is easily differentiated in this way from a triangular one,and from the values of the moments the dimensions of the mole-cule can be obtained.( b ) Prom the number and values of the vibrational frequencies ofthe molecule.For a triangular triatomic molecule the angle a tthe apex between two similar bonds can be found from the threecharacteristic frequencies. 89 9Raman Spe~tra.~9 lO-Wlien monochromatic light is scatt’ered bythe molecules of a transparent substance, the greater part has itsfrequency unchanged, but a small fraction is scattered a t discreteother frequencies, the frequency differences between exciting andscattered lines corresponding to changes in one of the characteristicvibrational or rotational levels of the molecule. Rotational tran-sitions are indicated by lines very near the spectral line scatteredwithout frequency change ; vibrational transitions by lines muchfurther away.The latter are not coupled with simultaneousrotational changes, i.e., they correspond to Q branches (Am = 0 ) ,and therefore afford much clearer data on vibrational levels than dothe near infra-red absorption bands, which are restricted to vibrationchanges involving a change of electric moment, and are complicatedby P and R rotational branches. Raman lines are excited for alltypes of vibration in which there is a change of polarisibility withphase.ll The two methods of investigation are thus supplementaryto one another, and, besides directly affording material on which tobase views of molecular structure, are, taken together, of very greatimportance in interpreting the complexities of electronic bandspectra (p. 371).The study of this new scattering phenomenon, predicted by A.Smekal 12 and first discovered by (Sir) C.V. Raman,13 has now beentaken up by a great number of investigators. The scattered lines8 N. Bjerrum, Ber. deut. physikal. G‘es., 1914,16, 737; R. C. Yates, Physical9 K. W. F. Kohlrausch, “ Der Smekal-Raman Effekt,” Springer, Berlin,10 C. Schaefer and F. Matossi, ‘‘ Der Ramaneffekt,” Borntraeger, Berlin,11 A. S. Ganesan and S. Venkateswaran, I n d . J . Phys., 1929, 4, 195.l2 Natumuiss., 1923, 11, 873.13 C. V. Raman and K. S. Krishnan, Nature, 1928, 121, 501, 619; I n d . J .Rev., 1930, 36, 555.1931.1930.Physics, 1928, 2, 399THE STRUCTURE OF SIMPLE MOLECULES. 37 1are faint, and most experimenters have used modifications of tttechnique due to R.W. W00d.l~A. Dadieu and K. W. F. Kohlrausch l5 were the first clearly toshow that particular atomic groupings give characteristic Ramanlines. They identified the single Raman line observed for diatomicmolecules with the natural frequency of the system as given by theordinary mechanical expression :-1 frequency = 2x ,J&orwhere w = frequency (sec.-l), M = the reduced mass of the system(1/M = l/Ml + l / M 2 ) , and4 = the force constant of the link whichis vibrating, t h a t is, the force which arises when the nuclei are dis-placed unit distance from their equilibrium position. The forceconstant f is approximately proportional to the energy of dissociationof the link to which it refers, as is shown by the constancy of theempirical expression :f = 5.86 x 10-2Mw2 dynes/cm.v(cm.-l) 2/M(gms.)/A(where A is the dissociation energy of the link in kilocalories permole), which varies over a wide range of examples from 290 to 390.The amplitude of Vibration a can be obtained from the relation :a (cm.) = 8-187 x lo4 d l / M o ,from which can be fount1 the mean restoring force during thevibration :Values of the quantities f and K are given in Table I (p.401).I n the case of more complex molecules, lines of particular fre-quencies varying only slightly in different compounds have beenidentified with particular linkages, and in some cases with particulartypes of vibration of those linkages, i.e., the bending or stretching ofthe link.l6 As with the near infra-red measurements, the numberand value of the vibrational frequencies, and of the rotationalfrequencies of the Raman lines, enable us to deduce the size, shape,and force constants of molecules that are not too complex.Aninteresting development has been the construction of molecularmodels with masses and springs which closely imitate the Ramanspectra of carbon tetrachloride, benzene, etc.17N. N. Pal and P. N. Sen Gupta, l n d . J . Phy8., 1930,5,609.K (dynes) = fa/2 = 24.0 x 10-lO 2/03Ml4 Physical Rev., 1930, 36, 1421; Trans. Paraday SOC., 1929, 25, 792;l6 Ber., 1930, 63, [B], 251.l6 D. H. Andrews, P h y s w ~ l Rev., 1930, 36, 544.l7 C. F. Kettering, L. W. Shutts, and D. H. Andrews, ibid., p. 531372 SIDGWICK AND BOWEN :Raman data, when fully interpreted, promise to provide moreaccurate knowledge of the structure of molecules than any otherspectral method.Much work is now being done in following theshift of particular lines associated with the vibration of particularlinkages (and so related to their force constants) in series of similarcompounds, and from work of this kind a great deal of light is likelyto be thrown on constitutive problems of quite complex organiccornpounds.15s 18, 155absorbradiation at frequencies which produce an electronic transition,simultaneous changes also occur in the vibrational and rotationalstates of the molecule, leading to the production of a complex bandsystem associated with each electronic transition. l9 The case ofdiatomic molecules has been very fully investigat'ed, and greatadvances have been made in such problems as the coupling of largeor small vibration changes with the electronic transition, and theeffect of nuclear spin on the rotational states of the molecule.Suchcompleteness of detail is unlikely to be attained for more complexmolecules for some time; nevertheless it is possible in certain casesto arrive a t a structure for a polyatomic molecule from a consider-ation of its electronic absorption spectrum in the gaseous state.The analysis of the spectrum is facilitated by introducing the fre-quencies of the normal molecule as obtained from Raman or nearinfra-red data. I n favourable cases the moments of inertia of themolecule both in the normal and in the excited state can be calculatedfrom the fine structure of the vibration bands, while from the re-lationships of the frequencies of the vibration bands themselves theforce constants of the two states can be obtained.The method isthus very similar to that used with Raman or near infra-red spectra,with the addition that structures can be deduced both for the normaland for the electronically excited molecule. It has, however,serious limitations ; the complexity of the spectrum is liable to leadto incorrect assignment of lines; the spectrum may be structure-less, as with HI or C1,O; and where large moments of inertia areinvolved it is difficult to obtain satisfactory resolving power for theexamination of the rotation lines.I n Table I are given data on the structure of molecules obtainedby spectral methods.Entirely satisfactory results by any of thesemethods are a t present limited to diatomic and rectilinear triatomicmolecules. Of more complex molecules, H,O 1 4 0 9 14*, 149, H,S 1499 143,C10, 15*, and SO2 152 are undoubtedlytriangular, NH, 141 is pyramidal,l 8 Dadieu and Kohlrausch, Zoc. cit., (ref. 15); M. E. High, Physical Rev.,l 9 Ann. Reports, 1926, 23, 296.Electronic Band Absorption Spectra.-When molecules1931,38, 1837; W. D. Harkins and H. E. Bowers, .ibid.,ip. 1845TBE STRUCTURE OF SIM.PLE MOLECULES. 373and COCI, 151, S,Cl,, SOC1, 152, and CH,O 144 are Y-shaped, but thevalues of the angles and distances a t present obtained by spectralmethods must be regarded as subject to revision.X-.Ray Methods.These may be discussed under two heads, according as the materialexamined is a solid or a gas.Determination of Crystal Rructure by X-Rays.-This applicationof X-rays is too familiar to need detailed discussion here.20 Itdepends on the power of the atoms, or rather of their electrons, toscatter the X-rays, so that the crystal can be used as a grating, theinteratomic distances being of the same order as the wave-length ofthe radiation.Hence, if the wave-length is known (this can now bechecked by the use of ruled gratings at a very small glancing angle),the spacing of the atomic grating can be determined. If the arrange-ment of the atoms in the crystal can be ascertained (alternativearrangements are sometimes possible), we can calculate from themeasurements the distances between pairs of atoms.For the simplerstructures these distances can be determined with an accuracy of0.05--0.1%.21 The method was extended by P. Debye and P.Schemer 22 to crystal powders, so that it can be used where it is notpossible to obtain single crystals of any size.X-Ray Interference in Vapours.-This is a new development ofgreat importance, which we owe to Debye and his 24, 25, 26, 27In the solid state the molecules are under some restraint, and thedistances between the atoms, and more especially the valency angles,may be thereby modsed. Debye and Scherrer’s application oftheir powder method to liquids leads to great difliculties of inter-pretation, as we are not sure whether the distances we are measuringare between atoms of the same or of neighbouring molecules.28With a gas these difficulties do not arise ; the regular distances mustbe between atoms of the same molecule in an unconstrained state.On the other hand the scattering power of the quantity of materialzo See W.H. and W. L. Bragg, “ X-Rays and Crystal Structure,” 1926;R. W. G. Wyckoff, “ The Structure of Crystals,” 1924.z1 V. M. Goldschmidt, Geochem. Vert., 1927, 8, 21.22 Nach. Ges. Wiss. Bdttingen, 1916, 16; Physikal. Z., 1916, 17, 277. Seealso A. W. Hull, Physical Rev., 1917, 10, 661.23 P. Debye, L. Bewilogua, and F. Ehrhardt,’PhysikaZ. Z . , 1929, 30, 84;P. Debye, &id., p. 524; H. Mark, 2. angew. Chern., 1931,44, 125.z4 P. Debye, Physikal. Z., 1930, 31, 142, 419.z 5 P.Debye, Z . Elektrochern., 1930, 36, 612.z6 L. Bewilogua, Physikal. Z . , 1931, 32, 265.z7 H. Gazewski, a i d . , p. 219.’* see, however, Debye, aid., 1930, 31, 348; Debye and H. Menke, ibid.,2nd Edn., 1931.p. 797374 SIDGWICK AND BOWEN:contained in a small volume of the gas is minute in comparison withthat in a solid or liquid, and prolonged exposures are necessary.Originally some 24 hours were required, but this has now beenreduced to 4 or 5. The method is essentially the same as that usedfor powders or liquids, a narrow beam of X-rays being passed througha small chamber through which the vapour of the substance is flow-ing, and the scattered rays being received on a photographic plate.The calculation of the interatomic distances from the trace on theplate involves considerable mathematical difficulties ; allowancemust be made for the distortion of the electronic orbits, and also forthe Compton effect.These difficulties have now, however, beenovercome,29 and it has been possible to measure the distances with anaccuracy greater than 1 yo.Method of Electron-Ray Interference.We now know that electrons in motion are accompanied by, orconsist of, systems of waves whose length is given by the de Broglierelation :A = h/mvwhere m is the mass and ‘u the velocity of the electron.30When a narrow pencil of electrons passes through a vapour, theelectrons are scattered, and their waves produce interferencepatterns which can be received on a photographic plate.Thus thegeneral nature of the method is the same as in Debye’s experimentswith X-rays. The necessary corrections for determining thedistances have now been worked and the results agree wellwith those obtained by the X-ray method : thus for the distancesbetween the chlorine atoms in carbon tetrachloride R.Wierl 319 329 33, 34, 35 found 2.98 A. and Debye 2.99 9 0.03 A. Therelative accuracy of the two methods has been in dispute, but wemay conclude 36 that the errors of the electron ray method are slightlythe larger. It has, however, certain great practical advantages overthe X-ray method. The interaction between the electrons and the29 For a general account, see Debye, in ‘* Chemistry a t the Centenary (1931)Meeting of the British Association.”30 For its experimental verification, see G.P. Thornson, Nature, 1928, 122,279 ; “ Wave Mechanics of Free Electrons,” New York, McGrew Hill BookCo., 1930.See also Mark andWierl, “ Die experimentellen und theoretischen Grundlagen der Elektronen-beugung,” Berlin, Borntraeger, 1931 ; “ Elektroneninterferenzen,” LeipzigerVortriige, 1930, p. 13 ; Ann. Reports, 1930, 27, 31.32 2. Elektrochem., 1930, 36, 675.34 Wierl, Physikal. Z., 1930, 31, 366, 1028.35 Ann. Physik, 1931, 8, [v], 521.36 L. Bewilogua, Physikal. Z . , 1931, 32, 114.31 H. Mark and R. Wierl, 2. Physik, 1930, 60, 741.33 Nuturwiss., 1930, 18, 205THE STRUCTlJRE OF SIMPLE MOLECULES. 375molecules of a gas is much more intense than that of X-rays, and theelectrons have a much stronger photographic effect; these twocauses cut down the time of exposure to not more than 1/10,000 ofthat required for X-rays.I n Wierl’s experiments electrons ofabout 40 kilowatts energy (wave-length 0.06 pi.) were used, and thetime of exposure was not more than a few tenths of a second. Thisis more than a mere practical convenience. Many organic com-pounds decompose far below the temperatures at which they boilunder atmospheric pressure, and it is thus impossible to obtaintheir vapours except at great tenuity; such substances couldscarcely be examined by the X-ray method, as the feeble scatteringwould necessitate enormously long exposures, whereas with electronrays quite short exposures would suffice.The electron ray method is equally applicable to solids, and hereit has another advantage over the use of X-rays.Owing to the moreintense interaction of the electrons with the molecules, they penetratea very much shorter distance into the material than X-rays, and sogive us more information about the state of the surface layers.Heats of Formation of Links.The energy evolved when two atoms form it covalent link bysharing a pair of electrons (or absorbed when this link is broken)is a magnitude of obvious importance for characterising the link,and determining the thermodynamic stability of the moleculeproduced. For diatomic molecules this can be measured directlyby various methods; for others it can be calculated if we know theheat of formation of the molecule from its elements in their ordinarystates (e.g., solid carbon, gaseous hydrogen, oxygen, nitrogen, etc.),and also the heat required to convert these elements from theirordinary states into atoms-the heats of atomisation.When a, diatomic molecule composed of two similar atoms can bedissociated thermally to a measurable extent, the heat of atomisationor linking can be determined from the change of the dissociationconstant with temperature, by means of the van ’t Hoff isochore.In this way the molecules Cl,, Br,, I, and H, can be examined.Heats of Atomisation of Diatomic Molecules.37, 389 399 4Q, 419 42- (a)37 R.T. Birge, Molecular Spectra in Gases, Bull. Nat. Res. Council, 1926,ll.38 H. Sponer, “ Optische Bestimmung der Dissociationwarme von Gasen,”39 R.Mecke, “ Bandspektra,” Handb. Phys., 1929, 21.40 G. Herzberg, “ Die Priidissoziation und verwandte Erscheinungen,” Erg.41 M. Rabinovitsch, 2. Elektrochem., 1931, 37, 91.42 For complete literature, see Landolt-Bornstein, 6te Adage, ZweiterErg. exakt. Naturwiss., 1927, 8.exakt. Naturwiss., 1931, 10.Erganzungsband, 1931, p. 1614, etc376 SIDGWICK A.ND BOWEN:(b) The absorption bands of certain molecules (halogens, ICl, 0,)corresponding to an electronic excit.ation show a vibration bandstructure which converges to a sharp limit (accurately obtainable bya very short extrapolation of the band series), beyond which is acontinuous band stretching towards the short wave part of thespectrum. Franck has shown that the energy corresponding tothis limit is to be identified with the heat of dissociation of themolecule-not, however, into normal atoms, but into one normal andone excited atom.If the excitation state of the second atom can beidentified, and its energy subtracted from that corresponding to thespectroscopic dissociation, the normal dissociation energy is obtained.This method is capable of an accuracy of 0.2 kilocalorie if no error ismade in arriving a t the state of the excited atom produced. Theexcitation state is found from an exact knowledge of the spectro-scopic terms for the atom, together with the values of the normal(thermal) dissociation heat derived from methods less refined incharacter but not subject to this uncertainty as to the states of theproducts of dissociation.(c) The type of spectrum in (b) i s shown only by molecules inwhich the internuclear distance is greatly altered by electronicexcitation. In other cases, direct observation of the convergencelimits is not possible, because states of high vibrational quantumnumber are improbable. Molecules possessing electric momentsshow in the infra-red region bands corresponding to increases in thevibrational energy of the non-electronically excited molecule, theconvergence limit of which gives the dissociation energy of the linkto which the vibration belongs.This method involves a long anduncertain extrapolation, and is not available for non-polar moleculessuch as N2 or H,, which cannot change their vibrational states in thenon-electronically excited state by absorption.A more genera1method consists in an extensive and detailed analysis of the bandsystems shown by a molecule both in absorption and in emission.It is then possible in some cases to arrive at the values of the differentelectronic energy levels of the molecule, and a t those of the lowervibrational sub-levels associated with them. A long extrapolationof these vibrational sub-levels, varying in accuracy in different cases,and a determination of the distances of the limits from the groundlevel provide values for the heat of dissociation of the molecule,either into normal atoms if the sub-levels belong to the ground state,or into one normal and one excited atom if they belong to an excitedstate. In the latter event means must be found for specifying theexcited state of the atom produced.By this method a very largenumber of dissociation energies have been estimated, such as thoseof the molecules H,, Se,, Te,, CO, NO, AgCl, HgCl, LiH, as well as oTHE STRUCTURE OF SIMPLE MOLECULES. 377molecules not easily accessible to the chemist, as N2+, 02+, C,, CN,SiN, BO, TiO, CO+, SO, CS, HgH, Li,, Na,, K,.(d) The heat of dissociation DN, of the molecule N2 has beenobtained from that of the molecule N2+, DNz+ (method c), by makinguse of the relation :where I , and I2 are respectively the energies of ionisation of theneutral atom and the neutral molecule, which are obtainable fromspectroscopic data and critical potential measurements. Anaccurate solution of a problem of this kind requires precise identific-ation of measured data with particular energy states, which at lastseems to have been achieved in this case.Application to Polyatomic Molecules.-The sum of the energies ofthe links in a polyatomic molecule is directly obtainable by acombination of the ordinary thermochemical heat of formation ofthe substance with the heats of atomisation of the elements com-posing it.Where the ordinary heats of formation of the gaseousmolecules refer to the elements in a solid or liquid state, correctionmust be made for the latent heat of fusion and of volatilisation ofthat element. Many heats of linkage of this kind, as, for example,that of PH,, cannot yet be estimated for lack of the appropriatedata ; in this case, for phosphorus. Of the greatest importance is thequestion of the heats of linking in carbon compounds.The linkenergies in molecules of the type CH,, CCI,, CO, can be found if thelatent heat of volatilisation of solid carbon to carbon atoms is known.The most probable value of this quantity at the ordinary temper-ature is 150 kilocalories, as the values of the C-H link deduced fromit are fairly close to those obtained from the extrapolated convergenceof infra-red bands of organic substances (see above) and frompredissociation spectra, as described below.When the molecule contains more than one kind of link we canmake progress only if we assume that the energies of particularlinks remain sensibly constant in different compounds. Thisassumption cannot be true, but it appears to be nearly so for relatedcompounds.E’or example, by assuming that the link energy ofC-H remains constant, the values obta4ed for the link C*C from theheats of formation of the saturated paraffins up to C,, do not varybeyond the experimental error. For this calculation any heats offormation which refer to the liquid parafhs must be corrected forthe latent heats of volatilisation, which can conveniently be obtainedfrom H. von Wartenberg’s formula 43 with a further correction toreduce the value to the ordinary temperature. Similarly, fromdata for aromatic hydrocarbons, consistent values for the energies ofIs 2. Elektmchent., 1914, 20, 444.DN, == DN,+ + Iz - I 378 SIDGWICK AND EOWEN:the C-H and C-C links, but different from those for the paraffins, areobtainable.By extending the assumption into regions where itcannot be so accurate, and making use of the heats of formation ofethers, aldehydes, esters, amines, unsaturated hydrocarbons, etc.,fairly consistent values can be obtained for the energies of such linksas C-0, C=O, N-H, C=C, CEC, C-N, etc.Predissociation Spectra.-Certain molecules show, a t points in theirvibration-rotation absorption spectra associated with an electronicexcitation, a fusion of the rotation lines within the vibration bands,which can most simply be interpreted as the formation of unstablemolecules which dissociate into two atoms or residues.44 Theenergies corresponding to these limits are close to (though greaterthan) those of the links which are broken.I n this way the linkenergy in the S, molecule can be obtained, as well as approximatevalues for the link energy of C-H and C-C in aldehydes and ketones.Other Methods.-There are a few other methods of estimatinglink energies which are less accurate or less important.(a) Photosensitisation. An atom is excited to a known state byabsorption, and allowed to pass on this energy by collision to amolecule which is dissociated if the energy available is greater thanand close to its dissociation energy. The heat of dissociationH,O + H + OH can be roughly estimated in this way,45 which isof limited application.The energy of combination of two atoms,e.g., of Na and C1, to give a molecule can be passed by collision toanother atom, which is thereby raised to excited states recognisableby their fluorescent emission spectra. The highest emission stateobservable gives a lower limit for the heat of linkage of the moleculeformed.(c) Photometric methods.Where the molecule formed is inequilibrium with its dissociation products, as in 2BrC1 Br, +C12,46 its energy of linkage can be calculated by applying the van't Hoff isochore to its equilibrium constant, found by estimatingoptically the concentrations of the reactants. This can be done byphotometric means either on their absorption bands or on theirfluorescent emission spectra, according to the case examined.(d) Molecular beam method.47 There are two methods based on theuse of a " unidimensional " molecular beam of the substance.(1) When the atom possesses a magnetic moment and the mole-(b) Chemiluminescence.44 K.F. Bonhoeffer and A. Farkas, 2. pkysikal. Chem., 1928, 134, 337.45 E. Gaviole and R. W. Wood, Phil. Mag., 1928, 6, 1191; H. Senftleben4 6 W. Jost, 2. physikal. Chem., 1931, [ A ] , 153, 143,4 7 See further, p. 381.and (Frl.) I. Rehren, 2. Physik, 1926, 37, 529THE STRUCTURE OF SIMPLE MOLECULES. 379cule does not (Liz, Na,, K,, Bi,), the former only is deflected in aninhomogeneous magnetic field, so that the atoms and molecules canbe collected separately on a plate and their relative amountsestimated. Prom the temperature variation of the proportions theheat of dissociation can be calculated.4*(2) The relative proportion of atoms and molecules in a molecularbeam can be found by the spreading of a rapidly rotating beam.The heat of dissociation can t’hen be found as before from the temper-ature coefficient of the mass-action constant .492Measuremen.t of Dipole Moment.50If the centres of action of the positive and negative parts of amolecule do not coincide, the molecule is polar : it is electricallyequivalent to a rod with a positive charge a t one end and a negativecharge a t the other, and in an electric field it tends to arrange itselfwith its negative end towards the positive pole. Its dipole momentis given by the product of one of the charges into the distancebetween them. Every isolated atom is non-polar. When twoatoms share electrons, if they share them equally, the moleculeproduced will also be non-polar, but if unequally, it will be polar,51the atom which has the greater share being at the negative end of thedipole.Experiment shows that covalent links between unlike atomsare in general polar.The methods of measuring dipole moments depend almost whollyon the determination of dielectric constants. If E is the dielectricconstant of a medium of density d, containing the molar fractionsf,, f, of two substances of molecular weight M,, M,, the “meanmolecular polarisation ” PI, is related to the separate molecularpolarisations P,, P, by :f l M l + f2%d P,, = P,fi + P2f2 =“A & + 2 xThis relation depends on the Clausius-Mosotti equation, whichtakes no account of the mutual influence of the dipoles a t closeranges; it can thus only be applied when the polar molecules are so48 A.Leu, 2. Physilc, 1928, 49, 498; Lewis, ibid., 1931, 69, 786.49 I. F. Zartman, Physical Rev., 1931, 37, 383.50 P. Debye, “ Polar Molecules,” 1929; C. P. Smyth, “ Dielectric Constantand Molecular Structure,” 1931. See also H. Sack, “ DipoImomente undmolekulare Strukture,” Erg. exakt. Wiss., 1929,8,307, and Leipziger Vortrage,1929.51 The words polar and non-polar are used throughout in their strictphysical sense, and mean possessing or not possessing a dipole moment. Tothis meaning they should always be confhed : their use in other senses, forexample, to distinguish ionised from non-ionised links, or associated fromnon-associated liquids, has led to much confusion380 SIDGWICK AND BOWEN :far apart that this influence can be neglected, i.e., to a gas, or adilute solution of a polar substance in a non-polar solvent.A molecule can be polarised by the electric field in three ways :(1) The electrons are displaced with respect to the nuclei.Thisgives the electron polarisation PB. This change is very rapid, ofthe order of 10-15 sec. : it thus follows the oscillations of the electricfield up to the far ultra-violet.(2) The nuclei themselves may be displaced owing to the shift ofthe electrons. This atomic polarisation, PA, is less rapid, about10-12 - 10-13 see. : it follows the field up to frequencies in theinfra-red.(3) If the molecule has a permanent dipole moment, it will tendto orient itself in the field.This orientation polarisation, Po, isrelatively slow, requiring about 10-lO see.The dielectric constants themselves are commonly measured withwireless waves of the order of 100 m. wave-length, that is, with aperiod of about 3 x 10-7, so that the results include all three formsof polarisation. The relation of the molecular polarisation to thedipole moment was shown by Debye to be given by :P=++%+m) 4x v2where N is the Avogadro number, a,, the electronic and atomicpolarisations, p the dipole moment, k the gas constant per molecule,and T the absolute temperature. Hence in order to measure p werequire to eliminate PE and Pa. This can be done in two ways.P E and PA are independent of temper-ature, whereas Po, as the equation shows, is inversely proportionalto it, since the thermal agitation opposes the orientation of thedipoles.Hence if P is determined at several temperatures, andthe values are plotted against the reciprocal of the temperature, theresult will be a straight line, which will be horizontal if the substanceis non-polar, and if it is polar will be inclined to the horizontal at anangle from which p can be calculated.This is the most accurate method, since it eliminates both theelectronic and the atomic polarisation.(B) Optical method. A simpler but rather less accurate methoddevised by Debye and Lange is that in which the electron polar-isateion is determined by using oscillations which are too rapid tocause orientation, i.e., the waves of visible light, of which there areabout 1014 per second.The molecular refractivity, calculated bythe Lorenz-Lorentz formula, is the electronic polarisation. Henceif we subtract the molecular refractivity from the total polarisationas measured by wireless waves, we get the value of PA + Po. PA(A) Temperature methodTHE STRUCTURE OF SIMPLE MOLECULES. 381cannot be determined by this method. Its amount is usually small:for a substance of fairly large moment the orders of magnitude arePE 20, Pa about 5, Po 200. Debye has pointed out that somecorrection is automatically made for FA if we calculate the refrac-tivity not, as should strictly be done, for f i n i t e wave-length, butfrom the refractive index for sodium light. This uncertainty aboutPa is the weakness of the otherwise most convenient optical method.Where the moment is large t'he error introduced is not serious, butwhere it is small or zero, this term may become of greater importance ;any value of p less than about 0.4 x 10-l8 obtained by this methodmay mean that the substance is non-polar.Another method sometimes employed to obtain PE and FA is tomeasure the dielectric constant of the solid substance.We cannot,however, always be sure that orientation is impossible in thesolid.Most of the values of the dipole moment have been obtained bythe optical method, and in solution. Many substances have beenshown to give the same values of the moment in the gaseous state,and in solution in a variety of non-polar solvents such as benzene,carbon disulphide, carbon tetrachloride, and the liquid paraffins.Benzene is the most commonly used; but recent work has shownthat this particular solvent can sometimes combine with a solutein such a way as to affect its moment ; thus iodine has a moment of1-0 52 in benzene, but zero in hexane and cyclohexane : 53 aluminiumbromide a moment of 4.89 in benzene and zero in carbon disulphide.64Molecular Beam Method.--This is an entirely different method,which, although its results are so far less accurate than those of thedielectric methods, can sometimes be used where they fail, and in anyevent is of value as giving an independent codrmation of the truthof the general theory.It is founded on the famous atomic beamexperiments by which Stern and Gerlach determined the magneticmoments of atoms.Its first electrical application was due to E.Wrede,66 who showed in this way that the molecules of the alkalinehalides, which cannot be investigated by the dielectric methods, havemoments of the order of 10 x 10-18. It has since been greatlyextended by J. E~termann.~' The substance to be investigated isheated in a minute oven to a temperature at which it has a perceptible52 The moments of polar molecules have values up to about 8 x 10-l8E.S.U.6s H. Miiller and H. Sack, Pbysihml. Z., 1930, 31, 815.54 E. Bergmann and L. Engel, ibid., 1931, 32, 507.55 For a full account of this method and its various applications, see R. G. S.66 2. Physik, 1927, 44, 261.6 7 2. pbpiFUtl. Chm., 1928, B, 1, 164; 2, 287; Leipz.Vortr., 1929, 17.To save specs they are all multiplied by 10ls.Fraser, " Molecular Rays," Cambridge, 1931382 SIDQWICK AND BOWEN:but very small vapour pressure. A stream of molecules, too farremoved from one another to collide, and with a velocity given bytheir temperature, in accordance with the gas laws, issues througha narrow (0.01 mm.) slit into a high vacuum, and by means of asecond slit is cut down to a narrow and very thin ribbon of rays.This is passed through a highly inhomogeneous electric field, andthen received on a brass plate cooled with liquid air, and thetrace which the molecules form is observed with a microscope.I n the absence of the field the molecules go straight through theapparatus, and condense on the plate in a narrow vertical line, lessthan 0.15 mm.wide. When the field is put on (Estermann used21,000 volts) it affects even non-polar molecules, since the electronpolarisation causes an induced dipole, and so they move towardsthe stronger part of the field; but the trace shifts as a whole. If,however, the molecules are polar, the effect of the field on any onedepends on the inclination of its dipole to the field, and so the traceis broadened to an extent depending on the moment of the molecule.So far it has not been found possible to deduce more than a roughestimate of the moments.This method can be used with substances which are not volatileenough for the dielectric constant of their vapours to be measured,and which are not soluble enough in non-polar solvents for thesolution method to be practicable.Its most remarkable successwas with pentaerythritol, C(CH,*OH),, m. p. 250-255", which wasshown to have a moment of about 2.0 x 10-ls.11. RESULTS.Dimensions.The methods already described for measuring the lengths of thelinks between atoms give us the distances between the atomicnuclei. To make them intelligible we have to try to determine the" radii " of the atoms concerned. In the light of modern theoriesof atomic structure it is difficult to say exactly what the " outside "of an atom means, or what its true radius is. For our presentpurpose this difficulty can be avoided by using the word radius in thesense of effective radius, as meaning the contribution which eachatom makes to the length of the link with another atom.As we have seen, the dimensions of links can be determined bothin the solid and in the gaseous state.It does not seem that the stateof aggregation makes much difference to the length of a covalentlink; and this is to be expected, since the forces between the mole-cules of a covalent solid are small in comparison with those betweenthe component atoms of the molecule : in carbon tetrachloride, foTHE STRUCTURE OF SIMPLE MOLECULES. 383example, the latent heats of fusion and evaporation are both about7 kg.-cals. per g.-mol., while the separation of the CCl, moleculesinto their component atoms needs about 270 kg.-cals. On the otherhand, in discussing the data derived from the study of solids, whichare by far the most numerous, we have to deal with the distinctionbetween the two kinds of link, electrovalent and covalent; thisambiguity does not arise with gases, since the only molecules whichcan be obtained in the gaseous state, except at very high temper-atures, are covalent. But with solids both kinds of link occur, andit is clear, largely through the work of V.M. Gold~chmidt,~8 that thenature of the link has an effect on its length. This conclusion,however, only emerges after a rather detailed examination of thefacts. The values given by Goldschmidt and others for the radiusof an atom in the neutral and ionised states differ widely (e.g., K2.27, K+ 1-33 ; C1 0.97, C1- 1-81 A.U.) ; but the effects of a positiveand a negative charge are in opposite directions; they thereforeneutralise one another to a considerable extent in a salt, and whilethe radius of each atom is very different according as the link isionised or covalent, the effect on the sum of the two radii, which iswhat is actually measured, is much less. In fact it is of the sameorder as that of two other influences which Goldschmidt hasemphasized.The first is the deformation of the ions by one another,to which are due the small changes observed in the differences of theinteratomic distances of, say, the sodium and potassium salts of thesame halogen as we pass from one halogen to another : this mayamount to as much as 5%. The second, which probably applies tocovalent as well as to ionised links, is the effect of the type of lattice,of what Goldschmidt calls the “ co-ordination number,” which hasnothing to do with the Werner theory, but is merely the number ofnearest neighbours which the atom has in the crystal.As thisnumber gets smaller the distances between the atoms decrease, andin extreme cases (going from 12 to 4) as much as 15% : the decreaseis, however, sufficiently regular to be allowed for. When regard ishad to these modifying influences, it can be shown that there is adefinite change in the distance when the link passes from the electro-valent to the covalent form. In the compounds of silver andcadmium given in Table I1 (p. 402), those which are ionised in thecrystal are distinguished by square brackets, and it will be seenthat in all of these the observed distance is greater than that cal-culated for the covalent state.Often the distinction between thetwo kinds of link appears more clearly from the type of crystal6 8 “ Geochemische Verteilungsgesetze,” VII, Oslo, 1926 ; VIII, Oslo,1927; Ber., 1927, 60, 1263. See also L. Pauling, J. Arner. Chern. SOC., 1927,49, 765384 SIDGWICK AND BOWEN:lattice, the covalent compounds favouring, as we should expect, themore open types, while true salts assume the most close packedform.In considering molecular structure we are essentially concernedwith the covalent link, and with the effective radii of neutral at0rns.5~A list of these radii for some of the more important elements is givenin Table 11. The constancy of these magnitudes, even under verydiverse conditions of observation, is surprising.The distancebetween two singly linked carbon atoms is found from the crystalstructure to be 1.54 A.U. in diamond,60 1.6 in solid ethane,61 1.55in the side chains of hexamethylbenzene,62 and 1.55 in long-chainparaffins 63 ; while by electron scattering we get 1.5 from the vapourof paraffins and naphthene~.~4 The “ aromatic ” link is 1-42 ingraphite,64 1.45 in solid hexamethylbenzene,62 1.45 in solid naph-thalene,65 and 1.4 in benzene vapour as measured both by X-ray andby electron scattering.34~ 35 The double link C:C is 1.35 in solidstilbene,66 and 1-31 according to the spectrum of the Swan bands.67The agreement between the interatomic distances observed incompounds, and those calculated from the values for the elements,whether the data are got from the solid or the gas, and whether bymeans of the crystal structure, or the band spectra in any of theirforms, or the scattering of X-rays or electrons, is remarkably close,not only among organic compounds, but generally, even among thecompounds of the metals where these are not ionised; and it holdsalso with the hydrogen halides, in spite of the exceptional characterof the hydrogen atom.A series of examples is given in Table 11,the calculated values being obtained from the atomic radii in thesame table. The values marked “ corr.” are corrected on thehypothesis that a double link is 14% and a triple 23% shorter than asingle link. These are the observed differences with carbon (0.22and 0-36 b.U.); and while we do not know the effect on otherelements, we may assume that it is of the same order, especiallysince the interatomic distances for carbon and the succeeding elements5a A remarkable series of simple relationships between the atomic radii(especially those of the metals) and the atomic numbers has been pointed outby W.Hume-Rothery (Phil. Mag., 1930, 10, 217).6o W. Ehrenberg, 2. Krist., 1926, 63, 320.61 H. Mark and E. Pohland, ibid., 1925, 82, 103.62 (Mrs.) K. Lonsdale, Proc. Roy. SOC., 1929, 123, 494.63 A. Mdler, ibid., 1927, 114, 542 ; 1928, 120, 437.64 E. Ott, Ann. Phy8ik, 1928, 85, 81.65 K. Banerjee and J. M. Robertson, Nature, 1930, 125, 456.6 G J. Hengstenberg and H. Mark, 2. Krist., 1929, 70, 283.67 Quoted by I(.H. Meyer and a. Mark, “Aufbau d. hochpolymerenorg. Naturstoffe,” Leipzig, Akad. Verlagsges., 1930, p. 17THE STRUCTURE OF SIMPLE MOLECULES. 386present a much more regular series if they are corrected on thisbasis : c-c. E N . o=o. F-F .Observed ............... 1-54 1.11 1.20 1-36Correction - 0.34 0.20Corrected ............... 1.54 1-45 1.40 1.35In polyatomic molecules the measurement of interatomic distancescan also give us information about the angles between the valencies.The general question of stereochemical configuration will be dis-cussed later,68 but we may consider here the very remarkableinvestigations of Debye and of Wierl with their collaborators, bythe X-ray and the electron method respectively, on the chlorinatedmethanes.They measured, with concordant results,25* 26 theC1,Cl distances in carbon tetrachloride, chloroform, and methylenechloride, and the C-C1 distance in methyl chloride. In the sym-metrical CCl,, the valency angles are all obviously 109.5". From theobserved CI,Cl distance of 2-99 A.U. this gives C*C1 as 1-82. InH,C*Cl, C*C1 has the same value. We can therefore assume that ithas this length in the intermediate compounds as well, and thisenables us to calculate the angles between the C*C1 valencies as follows :............... -c-c. N-N. 0-0. F-F .Compound. C1,CI. Val. angle.CC1, ................................. 2.99 109.5'CHC1, .............................. 3.1 1 116.4CH,Cl, ...........................3-23 123.8It is clear that with the successive replacements of chlorine byhydrogen the distance between the carbon and the chlorine remainsconstant, but the angle between the C*C1 valencies increases (as theThorpe-Ingold theory assumes), and by about 6 or 7% on eachreplacement. The results are of great interest as giving us a,definite idea of the extent to which the valency angles can bemodified by the other groups present in the molecule.The general conclusion to which the study of molecular dimensionsleads is that in covalent links the effective radii are remarkablyconstant, and are but little affected either by the conditions of themolecule, whether solid, liquid, or gaseous, or by the other atomswhich it contains. The angles between the valencies are much moresubject to change.In the older stereochemistry great stress waslaid on the valency angles, but relatively little attention was paidto the interatomic distances. It is now clear that the constancy ofthese two factors is in the reverse order.Heats of .Formation of Links.As we have seen,69 these values can be determined for diatomicmolecules directly; for polyatomic molecules the sum of the values68 p. 308. 6s p. 376.REP .-VOL. XXVIII. 386 SIDGWICK AND BOWEN:for all the links in the molecule can be calculated if we know theheat of formation of the molecule from its elements, and the heats ofatomisation of those elements. If we are to obtain values for theindividual links, we must assume that these are independent of theother links in the molecule, or that we know how the latter affectthem.The heats of atomisation of the elements, a knowledge of which isessential to the problem, have only become known with any accuracyin the last few years-even now only a limited number are known-and hence the subject is of comparatively recent development,One of the first to draw attention to it was K.Fajans,‘O who showedthat the heat of rupture of the C-C link was almost the same inethane and in diamond. Further investigations were made byA. von Weir~berg,~~ A. E ~ c k e n , ~ ~ H. G. Grimm,73 and H. Wolff, andothers; the results are summarised by Grimm 74 and by Eucken ‘5 ;their data, however, need some revision in the light of later deter-minations of the heats of atomisation.The last column of Table I contains a series of values of the heatsof rupture of covalent links.For a diatomic molecule the heat ofrupture of the link is twice the heat of atomisation. Two othervalues of the heat of atomisation should be added; for solid sulphur65-6 and for solid carbon 150 kg.-cals. per gram-atom. The heat ofrupture of the C-C link in solid carbon is of course half this, or75 kg.-cals.The values given in the table for compounds are mostly derivedfrom their heats of combustion through the heats of formation.Where the links are all the same (H,O, NH,, CH,), the value givenis the total heat divided by the number of links. Where they aredifferent, rather uncertain assumptions must be made as to theconstancy of the heat of a particular link.With the organic com-pounds the value 93-6 for C-H (derived from methane) is usedthroughout. This is probably accurate for alkyl radicals. .A com-parison of benzene and naphthalene derivatives indicates that theheats of the links C-C and C-H are about 9 units higher when thecarbon forms part of an aromatic ring, but as the basis of thesecalculations is somewhat doubtful, the aromatic compounds areomitted from the table. This uncertainty as to the effect on theC-H link of the state of combination of the carbon affects the values70 Ber., 1920, 53, 643; 1922, 56, 2826.71 Bey., 1919, 52, 1501; 1920, 53, 1347, 1519; 1923, 56, 463.7 2 Annalen, 1924, 440, 111.73 2. physikd. Chem., 1922, 102, 134; 2. Elektrochem., 1925, 31, 474.74 Geiger-Scheel, “ Handbuch der Physik,” 1926, 24, 532.7 5 “ Handbuch der chemischen Physik,” Leipzig, Akad.Verlagsges., 1930,p. 882THE STRUCTURE OF SIMPLE MOLECULES. 387given for multiple links of carbon to carbon, nitrogen, and otherelements ; these are calculated on the value found for C-€I in theparaffins, as we have no means of finding its true value in theethylene and acetylene derivatives. As they stand, the values formultiple links are interesting :Abs. Rel. Abs. Rel. Abs. Rel. Abs. Rel.C--C 71.0 1 C-N 55 1 C-0 70.5 1 C-S 58.7 1C=C 125.2 1-8 C=N 111 2.0 C=O 163 2.3 C I S 127 2.2C Z C 165 2.3 -CzN 183 3.4 CGO 235.5 3.3-N?C 184 3-4It is remarkable that while with the link of carbon to carbon theheat of formation increases much less rapidly than the number oflinks, which entirely agrees with what we should expect from thebehaviour of unsaturated compounds, with the link of carbon tonitrogen, oxygen, or sulphur the heat of formation of a double linkis at-least twice, and that of a triple link more than three times,that of a single link.As will be realised, the question of the heats of formation of linksis of great importance, but so far the subject is little developed.We need to accumulate accurate data on the heats of atomisation ofmore of the elements, and the heats of combustion of a large numberof compounds of the most varied types.Dipole Moments.76The methods of measurement described above give us the dipolemoment of the whole molecule.This may be conceived t o be madeup of a series of partial moments pertaining to each of the links;these are obviously directed magnitudes, and their vector sum isthe moment of the molecule.If we knew the values of each of thepartial moments, and the angles which they make with one another,we could calculate the molecular moment. We cannot yet do thiswith any great accuracy, but it can often be done sufficiently nearlyto enable us to decide between two chemically possible structures,and in this way the study of dipole moments has already proved ofgreat value.In the first place, if the molecule is non-polar, the partial momentsmust balance one another, and the molecule must be symmetrical.The diatomic elemeiitary gases H,, N,, O,, Cl,, etc., are found to benon-polar, as we should expect.Triatomic molecules of the typeAB, should be non-polar if the three atoms lie in a straight line,7 6 Complete lists of dipole moments published up to date will be found inSmyth, op. cit. (1931) : also in Debye, " Polare Molekeln," Leipzig, Hirtzel,1929, with supplementary lists for 1929 and 1930. Moments quoted withoutauthority in the text (which are expressed in terms of the unit 1 x IO-l*E.S.U.) will be found in these lists388 SIDGWICK AND BOWEN :provided the links are the same, as they usually will be; if thevalencies are inclined to one another, the molecule will be polar.It has thus been shown that CO,, CS,, and N,O are rectilinear, whileH,O, H,S, and SO, are triangular. (Many of these conclusions areconfirmed by the spectra, and also by the scattering methods ofDebye and Wierl.) A molecule AB, will be non-polar if all the atomslie in a plane and the valency angles are equal; hence NH,, since ithas a moment of 1.5, cannot be plane but must be pyramidal, asmust PH, (0.55) and ASH, (0.15).A pentatomic molecule AB, canbe non-polar on the tetrahedral model, or if the five atoms lie in aplane. CH, and CCl, are non-polar, and the plane formula is ruledout, because if it were true CH,Cl, (in the trans-form, which mustbe the more stable) would be non-polar, whereas it has a moment of1.5. Thus the tetrahedral configuration is established, and thesquare pyramid, which was a t one time suggested, is shown to beimpossible.When we come to more complicated molecules, we need to getsome idea of the moments of individual links.We have first,however, to find the direction or sense of the moments. This canbe done by an ingenious method suggested by J. J. Thomson 77 andfirst used by J. W. Williams.78 Since the benzene ring is planar,the moments of t'he links C-X, C-Y in a para-substituted moleculeC,H,XY will lie in the same straight line. Hence if the directionof these moments with respect to the ring is the same, they willoppose, and if it is the opposite they will strengthen, one another.This enables us to divide the links into two classes of oppositesense : it is found, for example, that C-Cl, C-Br, and C-NO, belongto one class, and C-CI-I, and C-NH, to the other ; and it is easy tosee, on more general grounds, that the first class must have thenegative end of the dipole remote from the ring.In finding the moments of individual links, the first difficulty isthat of the C-H link.All saturated paraffins (22 have so far beenexamined 79) are non-polar; but it can easily be shown that, if weassume the tetrahedral model, this absence of polarity can beexplained by the symmetry of the molecule, and is compatible withany value of the moment of C-H. There is good reason to thinkthat this moment is small: it is commonly assumed to be 0.4(Williams, and A. Eucken and L. Meyer 80), but all that we reallyknow is that it lies somewhere between 0.4 and zero.has calculated the values for C-H and C-Cl from the observedL.E. Sutton7 7 Phil. Mag., 1923, 46, 513.79 See R. W. Dornte and C. P. Smyth, J . Amer. Chem. SOC., 1930, 52, 3 5 4 .* l Proc. Roy. SOC., 1931, 133, 689, note.Physikal. Z . , 1925, 29, 174.Phy8ikal. z., 1929, 30, 397THE STRUCTURE OF SIMPLE MOLECULES. 389moments of chloroform and methylene chloride, using the anglesbetween the C-Cl valencies given by the measurements of Debyeand Wierl, on the assumptions (a) that the C-H valencies inmethylene chloride have an angle of 109.5", ( b ) that this angle isreduced by the expansion of the C-Cl angle to 100". He finds thatm(C-H) (this is a convenient symbol for the moment of the linkC-H) is for (a) 0-15, and for ( b ) 0.20 : the corresponding values form(C-Cl) are (a) 1.5 and ( b ) 1.41. The moment of C-H is in anycase small, compared with mo8t of those with which we have to deal,and we may provisionally assume the value 0.4.The moments ofother links can then be calculated from the observed moments ofthe simpler molecules. For example, m(CH,Cl) = 1-9 : the resultantof the moments of the three C-H links is equal (assuming angles of109.5") to that of one : hence m(H,C-Cl) = m(H-C-Cl) = 1.9. Asm(C-H) = 0-4, m(C-Cl) = 1.5. The uncertainty as to the valueof m(C-H) implies that m(C-Cl) may be as large as 1-9. Themoments of other links can he calculated by similar methods, andthe results are given in Table I11 (p. 402), the atom which is at thepositive end of the dipole being always printed first. These valuesare only provisional; they depend on three assumptions whichcannot be strictly true : (1) the value for m(C-H) ; (2) the assump-tion that the value for a given link is unaffected by the other linksin the same molecule : this seems to be approximately true exceptin the aromatic derivatives (see p.392); (3) the assumptionthat the valency angles can be taken to be 109.5". This last pointinvolves two questions. As we saw from the distances in thechlorinated methanes, the angles between the valencies of a 4-covalentatom such as carbon vary to some extent with the nature of theatoms attached to it, but amounts of variation such as were foundin these compounds would not change the values for the links bymore than a few tenths of a unit. It is, however, maintained byPauling3 that with covalencies of 2 or 3 the normal angle is not109.5" but 90".This would make a more serious difference to thevalues calculated for the individual links, when the central atom hasa covalency of less than 4. For example, water has a moment of1.87. If the angle between the 0-H valencies is 109.5", m(0-H) =1.87 + 1.155 = 1.62. If it is go", m(0-H) = 1-87 + 1.414 = 1.32.In the same way, m(NH,) -= 1-5; if the angles are tetrahedral,m(N-H) = 1.5 : if they are 90", m(N-H) = 1.06. The figures inthe table are calculated for angles of 109.5" and a C-H value of 0.4.Inspection of the table shows that (1) the element of the earlierperiodic group (counting hydrogen as belonging to Group I) is alwayspositive so far as is known ; but we do not yet know the moments ofany links of carbon to elements in the first three groups other tha390 SIDGWICK AND BOWXNhydrogen.(2) I n the link X-Y, where X and Y are in differentperiodic groups, if X, the positive member, remains the same, andY represents a series of elements from the same group, the momentalways diminishes as the atomic number of Y increases, except inC-0 and C-F, which seem to have smaller moments than C-S andC-CI; the exception does not hold with H-0 and H-S : m(H-F) isof course unknown. On the other hand,if we keep Y (the negativemember) constant, and replace X by another atom of the sameperiodic group, we get, so far as we can judge from the scanty data,the opposite result : the heavier X is, the lgrger the moment.It will also be noticed that in the series H-C, H-N, H-0, thoughthe increase is continuous, it is much greater between H-C (0.4)and H-N (1.5) than between H-N and H-0 (1.6).This may beconnected with the fact that in H-C alone the negative atom hasno unshared valency electrons.FZexibZe MoZecuZes.-A conclusion of very general interest whichemerges from the dipole measurements concerns the behaviour of" flexible " molecules and the meaning of the free rotation of singlylinked atoms. As we have seen, a para-disubstituted benzene withthe two substituents the same would be expected to have zeromoment, and many such molecules, for example,p-C6H4CI2,p-C6H4I2,P-C6H4(CH3),, are found to be non-polar. But others are definitelypolar : p-C6H4(O*CH,), 1.74, p-C6H4(CH0), 2.35, p-C6H4(CH2C1)2,2-23, etc.I n all these it will be noticed that the resultant momentof the substituent group does not lie in the central line of the molecule ;quinol dimethyl ether, for example, may, without any departure ofthe valency angles from the normal, have any configuration between(I) and (11).(11.)H,C/ '-<)-O\CH 3H3C \ O - ( l t o \(1.1 CH3Of these, (I) is symmetrical and non-polar, while (11) should havea considerable moment. The mutual repulsion of the dipoles wouldtend to make the molecules assume the non-polar form. L. Meyer 82has pointed out that such molecules are under two opposinginfiuences : (1) the work required to deflect the groups from thefavoured position, which is the intramolecular potential of thedipoles, and (2) the energy of the thermal agitation, which i s givenby kT, where k is the gas constant per molecule (= BIN), and Tthe absolute temperature. If the potential is much the larger, themolecule will remain in its position of minimum (if it is symmetrical,of zero) moment; if the thermal energy is much the larger, the2.physilcccl. Chem., 1930, [B], 8, 27THE STRUCTURE OF SIMPLE MOLECULES. 391potential will have a negligible effect, and the molecule will assumeall possible positions with equal frequency. Meyer also shows 83that the potential of the moments pl, b, at a distance d apart isapproximately p1 - p2/d3. Hence for a molecule a t the ordinarytemperature with two moments of the order of 1 x E.S.U.,the thermal energy kT(4 x 10-14 erg) will equal the potential ifd = 3 x cm., which is about twice the distance between twolinked atoms (other than hydrogen) in an organic molecule.Weshould therefore expect that in a molecule such as ethylene dichloridethe repulsion of the dipoles would have a large effect, while in quinoldimethyl ether and other p-di-substitution products of benzene,where the two dipoles are about 6 B.U. apart, its effect would bevery small. In compounds of the latter type, as we have seen, thisis borne out by experiment; and with ethylene dichloride directmeasurement with X-rays has shown 24 that the two C-Cl links aremainly in the most remote (" trans ") position, but that they aredisturbed by thermal agitation to an extent which correspondsclosely to that.required to account for the observed dipole moment.With molecules of this type, for which the electrical and thermalenergies are of comparable magnitude, it should be possible to showthat the moment increases with rise of temperature. This has beenthe subject of a number of papers 84; the facts are not yet quitecertain, but seem on the whole to support the theory.Chemists have long realised that the principle of free rotation ofsingly linked atoms with their attached groups did not necessarilyimply that these atoms were continuously rotating ; it was foundedon the absence of isomerides capable of passing into one another bysuch rotation, and hence it only implied that the molecule was freeto take up the most favoured of all the forms which this rotationpermitted. The application of the methods of scattering, and ofthe measurement of dipole moments, has shown us how far andunder what conditions the rotation can occur.It is clear that inconsidering, especially in relation to its reactivity, the forms whicha complicated molecule can assume, we must take into account theeffect of the forces between the dipoles on its configuration, and weare beginning to learn how this can be done.The Co-ordinate Link-The theory that a co-ordinate link is acovalency formed of two shared electrons, both derived from oneof the two linked atoms, has been regarded by some chemists as8s For a further discussion of this, see C. P. Smyth, R. W. Dornte, andE. B. Wilson, jun., J.Amer. Chem. SOC., 1931, 53, 4242.84 L. Meyer, loc. cit.; R. Sanger, Phyeikal. Z., 1931, 32, 21; Meyer, ibid., p.260; Smyth and co-workers, J . Arner. Chem. SOC., 1931, 53, 527, 2005, 2988,4242392 SIDGWICK AND BOWENimprobable, on account of the large electrostatic displacement whichit implies; but the measurement of the moments of molecules con-taining such links has confirmed it. With the bivalent carboncompounds, such as carbon monoxide and the isocyanides, there isevidence of the presence of a co-ordinate link in which the carbon actsas acceptor, and it has been shown 85 that the moments of thesecompounds agree closely with those to be expected if an electron istransferred from the nitrogen or oxygen to the carbon. Again, itseries of co-ordinated compounds have been shown to have excep-tionally large moments (from 4 to 9 units), such as the sulphoxidesand sulphones,s6 and the compounds of the halides of beryllium,boron, and aluminium with ethers, nitriles, and amine~.~' Theabnormal increase of molecular polarisation with concentration shownby the alcohols 88 indicates that their association is accompaniedby the formation of co-ordinate links of large moment. The relationbetween the power of a hydrogen atom to act as acceptor, and theposition in the periodic table of the atom to which it is alreadyattached, again supports the theory.89 It is well known that thispower varies greatly : the hydrogen in C-I3 cannot act as acceptor :in N-H it does so reluctantly, in 0-H and F-H very readily.I nthe same way the co-ordinating power of the hydrogen is muchgreater in N-H than in P-H, in 0-H than in S-H, and in F-H thanin C1-H; its power in X-H increases as X changes from an earlierto a later group in the first period, or within a given group fromthe second period to the first. But these are precisely the directionsin which the moment of X-H, in which H is always positive, increases ;and if the formation of a co-ordinate link consists in the hydrogentaking a share in a pair of unshared electrons of another atom, weshould expect it to do so the more readily, the larger its positivecharge.Dipole Moment and Organic Structures.The study of dipole moments has thrown light on a whole seriesof problems of structure in organic chemistry, and the results maybe briefly summarised.(1) Substitution in Benzene.-The theories of the influence ofgroups on the reactivity of organic molecules which have been put85 D.L. Hammick, R. C. A. New, N. V. Sidgwick, and L. E. Sutton, J.,1930, 1876.86 E. Bergmann, L. Engel, and S. Shndor, 2. physikal. Chem., 1930, [B], 10,397; 0. de Vries and W. H. Rodebush, J. Amer. Chem. SOC., 1931, 53, 2888.87 H. Ulich and W. Nespital, 2. angew. Chern., 1931, 44, 750.L. Lange, 2. Physik, 1925, 33, 169; J. Errera, Leipzjger Vortriige, 1929,pp. 25, 105.89 N. V. Sidgwick, Z. Elektrochem., 1028, 34, 440THE STRUCTURE OF SIMPLE MOLECULES. 393forward by Lapworth, Robinson, Ingold, and others agree in ascrib-ing the phenomena to a displacement of the electrons in the molecule,and any such displacement must be reflected in the dipole moments.The first attempt to test these theories from the physical side hasbeen made by L.E. Sutton,"o with respect to the problem of sub-stitution in benzene. The moment of a molecule R-X is differentaccording as R is an alkyl or an aryl group; and Sutton has shownthat there is a simple relation between the sign of this differenceand the directing power of the group X in benzene. If we call thosemoments of which the positive end is away from R positive, and thosein the opposite direction negative, then if m(Ar-X) - m(Alk-X)is positive, X directs ortho-para : if it is negative, X directs meta.For example :m(Ar-CH,) + 0.45 : m(Alk-CH,) 0 : Diff.+ 0.45m(A.r-NH2) + 1.55 : m(Alk-NH,) + 1-23 : Diff. + 0.32m(Ar-Cl) - 1-56 : m(Alk-Cl) - 2.15 : Diff. + 0-59m(Ar-CC1,) - 2-07 : m(CH3*CC1,) - 1.57 : Diff. - 0.50m(Ar-N02) - 3.93 : m(Alk-NO,) - 3.05 : Diff. - 0.88The first three groups of course direct ortho-para, the last two meta.Wherever this rule has been tested it has been found to hold.These results strongly support the view that the electrons of thebenzene ring are liable to suffer displacement under the influence ofa substituent, and that this determines the position which furthersubstituents take up ; moreover the direction of the displacementis that postulated for the electromeric effect by the Lapworth-Robinson theory. The observed displacement, as the aboveexamples show, is of the order of one-tenth of that which would becaused by the transference of an electron from one atom of thering to the next (about 7.4 units), and we might suppose either thata small proportion of the molecules underwent the full transference,or that all of them suffered a small displacement.As Sutton pointsout, the latter must be true, since in chlorobenzene, for example,substitution is much slower than in benzene; if only a smallproportion of the molecules were affected, the rest would react aseasily as before, and the rate of reaction of the compound as a wholewould not be seriously diminished.It is of interest to compare this conclusion of Sutton's with thesubstitution rule put forward by D. L. Hammick and W. S. Illing-worth.g1 This rule, which seems to hold in every case, states thatif in C,H,-X-Y, Y is in a later periodic group than X, then thedirection is meta, but that if not (i.e., if it is in the same or an earliergroup, or if there is no Y, as in C6H5Cl) then it is ortho-para. NowProc.Roy. Xoc., 1931, 133, 668. g1 J., 1930, 2358.N 394 SIDGWICK AND BOWEN:in a link X-Y, as we have seen, if Y belongs to a later periodic groupthan X, it is the negative end of the dipole, but if to an earlier, thepositive end. If we accept the conclusion, that the ortho-paradirecting power involves an electronic drift in the ring away fromthe substituent, we can distinguish three cases (the arrow in thering indicates the drift) :-I+ X-YIn the first and third, the drift is in the same direction as themoment of the substituent, and may be supposed to tend to relievethe strain which this causes; but in the second, where there is onlyone atom in the substituent group, we have to assume a drift in theopposite direction to the moment, which indicates that someprinciple, other than induction, is operative, which we do notunderstand.(2) Diphenyl Derivatives.-The Kaufler formula for diphenyl, inwhich one ring was supposed to be folded over on the other,92 wasdisproved by dipole rneas~rements,~~ which showed that thep,p’-di-derivatives X*C,H,-C,H,*X had almost the same momentsas the corresponding p-di-derivatives of benzene ; they were non-polar so long as the moment of X was symmetrical to the centralaxis of the molecule, and only polar when this could be explainedby the flexibility of the X group.(3) cis - trans - Isomerism. - A cis - disubstituted ethylene,CHXZCHX, should be polar, and its trans-isomeride non-polar, sothat the moments give a simple method of determining the con-figuration.This test has been applied by J. Errera 94 to the di-halogen substitution products of ethylene. He finds that thedichloride, dibromide, and chlorobromide in the trans-form are92 For a summary of the chemical arguments for and against this formula,see C. K. Ingold, Ann. Reports, 1926, 23, 119. For the explanationof theoptical activity of diphenyl derivatives, see F. Bell and J. Kenyon, Chem. andInd., 1926,4, 864; W. H. Mills, ibid., p. 884; W. H. Mills and K. A. C. Elliott,J ., 1928, 1291.93 J. W. Williams and A. Weissberger, J . Amer. Chem. SOC., 1928, 50, 2332;Z . phgsikal. Chem., 1929, [B], 3, 367; A. Weissberger and R. Sangewald,ibid., [B], 5, 237; J. W. Williams and J. M. Fogelberg, Physikal. Z., 1930,31, 363.$4 Compt. rend., 1926, 182, 1623; Physikal. Z., 1926, 27, 764; “Polarisa-tion didlectrique,” Paris, 1028THE STRUCTURE OF SIMPLE MOLECULES. 395non-polar, and in the cis-form have moments of about 1.5 : withthe chloroiodides one form has p = 0-57 and the other p = 1-27.Since the moments of C-CI and C-Br are practically identical, whilethat of C-I is smaller, we should expect a residual moment in thetram-chloroiodide but not in the tram-chlorobromide. The assign-ment of structures previously made to the isomerides on othergrounds agrees with the dipole measurements, except in thechloroiodides.This conclusion has been confirmed for the dichlorides by D e b ~ e , ~ ~who has shown by the X-ray method that the distance between thechlorine atoms in the cis-compound is 3.6 and in the trans-compound(4) Compounds of Type CA,.-The configuration of these com-pounds has been the subject of much discussion.Guillemin andV. Henri suggested, on the basis of spectroscopic measurement^,^^that a molecule CA, could have the form of a square pyramid withthe carbon at the apex. The X-ray examination of the crystalstructure of pentaerythritol, C( CH,*OH),, was believed to indicatethat the arrangement of the groups round the central carbon atomcould not be tetrahedraLg6 Later work has weakened the force ofboth of these lines of arg~ment.9~ The dipole moments appear tobe conclusive in favour of the tetrahedral structure.CH,, CCl,,C(NO,),, and C(CH2hal),, where ha1 = CI, Br, I, have all beenshown to be non-polar. On the other hand, compounds CA, inwhich A = O-CH,, O*C,H,, CH,*OH, CH,*O*CO-CH,, CH,*O*NO,,CO*O*CH,, CO*O*C,H, have moments from 0.8 to 3-9.98 These,however, are all groups with unsymmetrical moments, whoseflexibility is sufficient to account for their polarity. The absenceof polarity in pentaerythritol tetrachloride, tetrabromide, andtetraiodide, which was confirmed for the first two by the beammethod, is remarkable. A symmetrical and non-polar arrangementof the four CH,hal groups is of course possible, but it seems unlikelythat the potential of the moments would be sufficient to fix the95 V.Guillemin, Ann. Physik, 1926, 81, 173; V. Henri, Chem. Reviews,1927, 4, 189.g6 H. Mark and K. Weissenberg, 2. Physik, 1923, 17, 301 ; M. L. Hugginsand S. B. Hendricks, J . Amer. Chem. SOC., 1926, 48, 164.9 7 Fordhe spectroscopic evidence, see A. E. Ruark and H. C. Urey, “ Atoms,Molecules, and Quanta,” 1930, p. 436; for the crystal structure, I. Nitta, Bull.Chem. SOC. Japan, 1927,1, 62; A. Schleede, 2. anorg. Chem., 1928,168, 313;172, 121; also H. Miiller and A. Reis, 2. Krist., 1928, 68, 385; (Miss) I. E.Knaggs, PTOC. Roy. SOC., 1929, 122, 69.98 J. W. Williams, Phy8ikaE. 2.. 1928, 29, 683; L. Ebert, R. Eisenschitz,and H.von Hartel, 2. physikal. Chem., 1928, [B], 1, 94; I. Estermann, ibid.,1929, [B], 2, 287; Leipziger Vortrilge, 1929, p. 17; 0. Fuchs, 2. PhysiE, 1030,63, 824.4.7 A.U396 SIDQWICK AND BOWEN :molecules in this position, especially as the orthocarbonates,C( Oalk),, are polar. It is probable that steric influences co-~perate.~~(5) Bivalent Carbon Compounds.-The dipole moments indicatethat in carbon monoxide and the isocyanides the carbon is triplylinked to the oxygen or the nitrogen, the third link being co-ordinate :o z c R--MI-CThe link of carbon to oxygen or nitrogen has, as we have seen, aconsiderable moment, the carbon being positive. C=O andR-N=C should therefore be highly polar, and the moment inthe latter should have its positive end remote from the group R.Carbon monoxide is almost non-polar (0-l), and it has been shown 85that the moment of the -NC group in the aryl isocyanides (3.5) isin the opposite direction.This can only be explained by the trans-ference of an electron to the carbon in the formation of the (third)co-ordinate link, and the effect of such a transference through thedistance separating the two atoms is in good agreement with themagnitudes of the observed moments. The existence of a triplelink between the atoms is codrmed by the heats of formation andthe parachors, and further for carbon monoxide by the interatomicdistance (obs. 1.14, calc. 1.13 A.U.) and by the force constant (18.6(6) 0ximes.-A decision between the opposed theories of Hantzschand Meisenheimer as to the configuration of the syn- and anti-oximes has been promoted by the measurement of the moments ofx 105).(I.) O 2 T 4 - a 0 O+N-CH, o > N - o - f a 0 H,C-N+O (11.)the N-ethers of p-nitrobenzophenoneoxime. loo The -N+ 0group should have a moment comparable with that of the nitro-group, and hence the moment of the syn-compound (I) should belarge, and that of the anti-compound (11) small.It was found thatthe a-compound (m. p. Ego), which according to Meisenheimer hasthe syn-formula, gave p = 6-60, and the p-compound (m. p. 136"),1-09. This seems conclusive in favour of the Meisenheimer theory.The only known N-ether of p-nitrobenzaldoxime was found.to havea moment of 6.4, indicating the syn-configuration.(7) Axo-compounds.-It was pointed out long ago by Hantzschthat the remarkable stability of azobenzene (b.p. 293") shows thatit must have the more stable anti-configuration. This has beenconfirmed by the dipole moment, which is zero. The pmonochloro-99 A. Weissberger and R. Siingewald, Physilcal. Z., 1929, 30, 792.lo" L. E. Sutton and T. W. J. Taylor, J . , 1931, 2190THE STRUCTUXE OF SIMPLE MOLECULES. 397and p-monobromo-derivatives have almost the same moments lo1(1.55 and 1.42) as chloro- and brorno-benzene (1.55 and 1.52).(8) Axides and Aliphatic Diazo-compounds.-These compoundswere originally assumed to have ring structures, but this view waslater abandoned in favour of open-chain formulE, mainly throughthe work of Thiele and Staudinger, who showed that they gavederivatives containing these open chains.This argument is notconclusive, because the double link between nitrogen atoms (unlikethat between carbons) is very strong, and the rings, if present, aremore likely to break at the single link. The possible structures,assuming that the atoms have complete octets, areR-N<g nTR - N t N f N(1.) (11.) (111.)Of these, formula (I) should have a small moment, owing to thesymmetry of the ring, while the moments of (11) and (111) should belarge, because they contain a co-ordinate link. The volatility ofthe azides and diazo-compounds suggests lo2 that they have smallmoments; the parachor values lo3 are also in favour of the ringstructures, though the difference between the two calculated valuesis so small that this cannot be regarded as decisive.Recently, themoments of phenyl-, p-tolyl-, and p-chlorophenyl-azides have beenfound 104 to be 1-55, 1.96 and 0.35, indicating that the N, group hasa moment of about 1-5, with the negative end away from the aromaticring. This is the wrong direction for structure (111), and too smallfor (11), which should have a moment of 3 4 (compare diphenylsulphoxide, R,S + 0, p == 4.1). Also the practical absence ofpolarity in the p-chloro-compound indicates that the moment ofthe group is symmetrical to the axis, and this is possible only forstructure (I).Thus the moments favour the ring structure for the aromaticazides. This is remarkable, since the X-ray examination of thecrystal structure of the metallic azides has shown 105 that the azideion has a rectilinear codguration.This implies the presence oftwo double links, so that the ion must be written N-N-tN orN=N=N; it is thus quite symmetrical, and has no turning- f -lol El. Bergmann, L. Engel, and S. Sfindor, Ber., 1930, 63, 2572.lo2 N. V. Sidgwick, J., 1929, 1108.lo3 H. Lindsmann and H. Thiele, Ber., 1928, 61, 1529.lo4 L. E. Sutton, Nature, 1931, 128, 638; E. Bergmann and W. Schutz,lo6 S. B. Hendricks and L. Pitding, J . Amer. Chem. SOC., 1925, 47, 2904.ibid., p. 1077398 SIDGWICK AND BOWEN :moment; but if it passes into the covalent state by the addition ofan imaginary phenyl kation, this must attach itself to a terminalnitrogen, giving the highly polar and so presumably less stablestructure (11). This may be why the ion and the covalent form havedifferent structures.The moments of the aliphatic diazo-compounds have not yetbeen determined.Preliminary (unpublished) measurements byL. E. Sutton indicate that they are not large, as the volatility alsosuggests, and so favour the ring structures. The supposed opticalactivity found in the diazo-compounds by P. A. Levene, W. A.Noyes, and H. Lindemann, which would necessitate structure (111),has been shown to be due to an impurity.lo6General Stereochemical Conclusions.The classical methods of stereochemistry have shown that thereis a tetrahedral arrangement of the groups surrounding 4-covalentatoms of beryllium, boron, carbon, nitrogen, silicon, phosphorus,sulphur, copper, zinc, arsenic, selenium, tin, and tellurium I07 ; andan octahedral round 6-covalent atoms of aluminium, chromium,iron, cobalt, nickel,los copper, arsenic, rhodium, iridium, andplatinum.The examination of crystal structures shows that theseconfigurations, for 4- and 6-covalent atoms respectively, are almostuniversal. The only exceptions for which there is experimentalevidence are the 4-covalent compounds of bivalent palladium andplatinum, and quite recently, nickel. Werner's view that the4-covalent platinous compounds have the four groups and thecentral atom in a plane was attacked by Reihlen,lo9 but has appar-ently been vindicated by A. Hantzsch,llo who showed that the twoforms of P t ( ~ y ) ~ C l , have the same molecular weight in phenol.With palladium, F.Krauss and F. Brodkorb 111 obtained isomericforms of the analogous Pd(py),Cl, and of Pd(C2H5*NH,),CI,, andshowed that these had the same simple molecular weight in solution.T. M. Lowry 112 adduced evidence of a different kind in favour ofthese plane structures. He pointed out that R. G. Dickinson 113had found that while zinc, cadmium, and mercuric salts of the typeK,[X(CN),] formed cubic crystals, whose structure indicated atetrahedral form of the ion, the salts K,[PdCl,], (NH,),[PdCI,], and106 A. Weissberger and R. Haase, Ber., 1931, 64, 2896.107 For tellurium, see H. D. K. Drew, J., 1929, 560; T. M. Lowry and F. L.108 G. T. Morgan and F. H. Burstall, Nature, 1931,127, 854; J., 1931, 2213.109 H. Reihlen and K.T. Nestle, Annnlen, 1926, 447, 211.1 1 O Ber., 1926, 59, 2761.111 2. anorg. Chem., 1927, 165, 73.113 J . Amer. Chem. SOC., 1922, 44, 774, 2404.Gilbert, ibid., p. 2867.llZ Xature, 1929, 123, 548THE STRUCTURE OF SIMPLE MOLECULES. 399K,[PtCI,] formed tetragonal crystals, in which X-ray analysis showedthe metal to be at the centre of a square, with the chlorine atomsat the four corners.On the other hand, F. G. Angell, H. D. K. Drew, and W. Ward-law 11* have examined the two forms of the thioether compound(Et,S),PtCl,, and find that, while both have the normal molecularweight in benzene, their chemical behaviour shows greater differencesthan cis-trans isomerism will account for. In particular, with silveroxide the a-form reacts slowly with liberation of the thioether andprecipitation of platinous oxide or hydroxide, while the @form israpidly converted into the soluble and fairly strong base(Et,S),Pt(OH),.The structures which they propose for the twoforms seem for various reasons unsatisfactory, but their resultscertainly indicate that these compounds need further investigation.This question assumes peculiar interest in the light of Pauling’srecent conclusion from wave mechanics that bivalent nickel,palladium and platinum, unlike the non-transitional elements, canform 4-covalent compounds of the plane type, which can further bedistinguished by their smaller paramagnetic moments. This con-clusion has recently been supported by the discovery of s. Sugden l15that the nickel compound of benzylmethylglyoxime occurs in twoisomeric formsPh*CH,-$-G-CH, Ph*CH2-EI_;--CH3O t N N-OH O t N N-OH\g \& Ni/k oti4; R-OHPh*CH,-C-C-CH,r\HO-i t-+OH,C-C-C-CH,Phand that these are diamagnetic.With a tetrahedral configurationthe two forms would be optical antimerides, and should be para-magnetic.The general principles of structure which these physical investig-ations show to be applicable to the volatile compounds of the lighterelements, with which we are mainly concerned, may be brieflysummarised. G. N. Lewis’s conception of the two-electron link, inwhich the electrons may come either one from each of the linkedatoms (normal) or both from one (co-ordinate), holds for all but afew molecules,3 and the dipole moments indicate that the electronsare shared nearly (within 20%) equally between the two atoms.The maintenance of the valency octet is a condition of stabilitywhich is almost always fulfilled.For the configuration of themolecules the tetrahedral atomic model of van ’t Hoff has received114 J., 1930, 340. 115 J . , 1932, 246400 SIDGWICK AND BOWEN:the fullest support, not only for atoms forming four, but also forthose forming two or three links, although in the two last casesPauling's theoretical conclusions indicate a valency angle of 90"rather than 109.5", a view which it is not yet possible to test experi-mentally. The valency angles can change to some extent with thenature of the groups in the molecule, but apparently not muchmore than 15%.The effective radii of the atoms are now known, and are evidentlyremarkably constant factors in determining the configuration ofthe molecule; apart from certain ascertained changes due to themultiplicity of the link (up to 20%) and in crystals to the natureof the lattice (rarely more than 5%), the differences betweenobserved and calculated values of the distances between linkedatoms scarcely exceed the experimental error.But the form whichthe molecule assumes, through the liberty of free rotation of singlylinked atoms, without change of the valency angles or of the lengthof the links, is largely determined by the intramolecular attractionsof its dipoles, especially when these are near together.As a final example, we may repeat the conclusions reached for aseries of familiar triatomic molecules :o=c-0, s=c=s :[NtN=N]- :N t 0 - N[C=N=O]-H-CZN :\HH-0\HH-So=shORectilinear.Spectrum, dipole moment.Crys t a1 structure.Spectrum, dipole moment.Crystal structure.Spectrum.Triangular.Spectrum, dipole moment.Dipole moment.Spectrum, dipole moment.The last example may be dealt with in more detail. The altern-ative structure O=SzO gives the sulphur a valency group of 10electrons, 8 being shared.This would presumably imply a straightline molecule, but we cannot be sure what effect the decet wouldhave. It is, however, a very improbable structure, because a valencygroup of more than 8 electrons never occurs unless either (a) theyare all shared or (b) it can be reduced to the normal form by assumingthat two of the electrons become inert; but (b) is only found in theheavier elements.The chemistry of sulphur supports this con-clusion. A quadrivalent and 4-covalent sulphur atom never occurs ;the stability of the optically active compounds of the type RR,S-+THE STRUCTURE OF SIMPLE MOLECULES. 401proves that they cannot assume the tautomeric form RR,S=O(containing the decet) which would lead to racemisation ; whileSC1, has been shown by T. M. Lowry and G. Jessop 115a to occuronlyin the solid state, and then probably as the salt [SCl,]CI. Thefinal proof that in SO, one of the oxygen atoms is singly and theother doubly linked is given by the values of the force constantsfor the two links, which are 7.23 and 4.93 x lo5 respectively.TABLE I.1G’3H-Hdui128w 2 rn w 2116H103 5.0611.322.24.55 151.2051.1071-351.932.262-660.9291.2821.4211-6171241251261261271267777128 4.14 15128 7.14 15118 117208 11863.5 11957.4 120,121.45.8 12136.0 122146.5102.286.770.911089.887.483-393.671-0125.21655511118018818470.572.6181.3160165235.558.712773.272.560.042.8126.90 3N2 NF-Fc1-CI F2 c1, 3.212-471.69129 1.32 15121121Bi2 Br-BrHF H-FHC1 H - C lHBr H-BrHI H-IH-0:&:*OH H-0NHS H-NH-SH-SCH.4 H - CC,Hs C-CC2H4 C=CC2H2 CECCH,*NH2 C NCH,*NCO C=NHCN C E NCH,-CN - C SCH,*NC -NECCH,*OH C-0I 2 1-1CH3*NH2 H-N4.43-562-9130 3.47 15131 2.94 15131 2.52 156.34 132 4-59 156-04 132 4-45 153-77 133 3-094.58 134 3.624-31 135 2-059-36 135 3.8816.4 136 6.324.86 132 2-2215151515151517-9 137 6.17 154-98 132 2.25 15 c-0 c=oc-0 c=oG O c-sc-s c=sC - c lC - c l11.9 137 4.49 151.14 6 18.6 15 6.28 153-01 133 1-44 153-12 138 1.48 15CHiBr C-BrCH,I C-I so, s=o2-61 139 1.23 152.15 139 1-05 15llba J., 1930, 782402 SIDGWICK AND BOWEN :TABLE 11.A.Atomic Radii in a.77. : from the Elements.Element. Radius. State. Ref. Xlement. Radius. State. Ref.H 0.37 Gas 123 Si 1.17 Solid 21C 0-77 Diamond 60 cu 1.28 Metal 146N 0-55 Gas 125 1.44 Metal 1400 0.60 Gas 124 1.12 Metal 147F 0.68 Gas 126 Zn 1.33 Metal 147c1 0.97 Gas 126 Cd 1.49 Metal 147Br 1.13 Gas 127 Ge 1.22 Metal 21I 1.33 Gas 126 Sn 1.40 Grey tin 21B.Dimensions of Links in B . U .Com-pound. Link.HF H-FHCI H-ClHBr H-BrHI H-IH,O H-0H--NN,O N-N co, 0-0H,S H-Scs, s-sH,CO C-0KClO, Cl-0K,SO, S-0H,CCI C-CICCl, C-C1CBr, C-BrSiC1, Si-C1GeCl, Ge-CISnC1, Sn-Cl3 c-0Distance. Distance. - Com- - Calc. Corr. Obs. Ref. pound. Link. Calc. Obs. Ref.1-05 0.93 7 CuCl Cu-Cl 2.25 2-34 1451.34 1.28 7 CuBr Cu-Br 2-41 2.46 1451-50 1.42 7 CUI CU-I 2.61 2.62 1451.70 1-62 7 cu,o cu-0 1.88 1.85 580.97 1.08 1.03 140 cu,s 2.32(l:i: g7 0-92 1.10 0.97 1411.37 1.13 1.14 62.30 2.37 2.38 34, 1422.52 2-25 24,27, 341-41 1.25 1433.63 3.40 { i:;: 2,:i41.37 1.15 1.2 1441.56 1.67 1.56 1531.64 1.66 581.74 1-83 25,261.74 1.85 25,261.90 2.05 342.14 2-02 342-19 2-10 342.37 2.33 34AgFI A r FAg[Cl] Ag-ClAg[Br] Ag-BrAg[I]a Ag-IAgIp Ag-IAg2O Ag-0 2: ;gI;BeS Be-SZnF, Zn-FZnO Zn-0ZnS Zn-SCd[F] Cd-FCd[O] Cd-0CdS Cd-S2.12 '2-46 582.41 2.77 212.57 2.88 212.77 3-05 212.77 2-81 212.04 2.04 212.48 2-61 581.72 1.65 1452.16 2.10 212-01 2.04 211-93 1.97 212.37 2-35 582-17 2.34 212.09 2.35 212.53 2.53 21TABLE 111.Dipole Moments of Links, x 1018.H-C 0.4 H-N 1.5 H-0 1.6 H-F (2)H-P 0-55 H-S 0.8 H-C1 1-03H-As 0.15 ' H-Br 0.78H-I 0.38C-N 0.4 C-0 0.7 C-F 1.3 c=o 2.3CZN 3.1 c-s 1.0 c-Cl 1.6C-Se 0.9 C-Br 1.4C-Te 0.7 C-I 1.2Y-C1 0-8 As-CI 2.0 Sb-Cl 3.8 P-J3r 0.6 As--Ur 1.7-~ ~~~116 E. E. Witmer, Physical Rev., 1926, 28, 1223; R. T. Birge, Proc. Nat.Amd. Sci., 1928, 14, 12; 0. W. Richardson and P. M. Davidson, Proc. Roy.SOC,, 1929, 123, 466. 11' R. Frerichs, Physical Rev., 1930, 36, 398; V.Kondratbev, 2. physikal. Chern., 1930, [B], 7, 70. G. Herzberg, Nature,1928, 122, 505; R. T. Birge, Trans. Paraday SOC., 1929, 25, 707; J. KaplanTHE STRUCTURE OF SIMPLE MOLECULES. 403l’roc. Nut. Acad. Sci., 1929, 15, 1929. 119 H. von Wartenberg and H. S.Taylor, Nach. Bes. Wiss. Qdttingen, 1930, 119.lZ1 R. Kuhn, Z. Physik,1927,39, 77. lZ3 R. T.Birge and C. R. Jeppesen, Nature, 1930,125, 463. lZ4 G. H. Dieke and H. D.Bebcock, Proc. Nat. Acad. Sci., 1927, 13, 670. lZ5 F. Rdsetti, ibid., 1929, 15,515. l z 6 R. Mecke, 2. Physik, 1927, 42, 390; Physikal. Z., 1927, 28, 479.1 2 7 R. Mecke, “ Bandspecktra.” 128 F. Rasetti, Nature, 1929, 124, 93 ;Physical Rev., 1929, 34, 367. lzS S. Bhagavantam, I n d . J . Phys., 1930, 5, 35.180 R. W. Wood and G. H. Dieke, Physical Rev., 1930, 35, 1355. 131 E. 0.Salant and D. Sandow, Physical Rev., 1931, 37, 373. 132 S. Venkateswaran,I n d . J . Phys., 1930, 5, 129. 133 Idem, ibid., p. 219; 1931, 6, 51. 134 R. G.Dickinson, R. T. Dillon, and IF. Rasetti, PhysicaE Rev., 1929, 34, 582. 135 P.Daure, Ann. Physique, 1929,12, 375. 136 S. Bhagavantam, Nature, 1931,127,817. 137 Kohlrausch, “ Der Smekal-Raman Effekt.” W. West and(Miss) M. Farnsworth, Trans. Faraduy SOC., 1931, 27, 145. 139 C. E. Clectonand R. T. Dufford, Physicul Rev., 1931, 37, 362.141 R. M. Badger and R.Mecke, 2. physikal. Chem., 192!3, [B], 5, 333; R. M. Badger, Physicul Rev.,1930,35,1038. 142 €3. K. PlylermdE. F. Barker, Physical Rev., 1931,38,1827 ;R. G. Dickinson, R. T. Dillon, and F. Rasetti, ibid., 1929, 34, 582; C. P.Snow, Proc. Roy. SOC., 1930,128,294. 143 TV. Mischke, Z. Physik, 1931,67,106.144 V. Henri and S. Schou, ibid., 1928, 49, 774. 145 V. M. Goldschmidt, Z.Elektrochem., 1928, 34, 459. 146 Idem, Z. physikul. Chem., 1928, 133, 397.147 J. W. Ewald and K. Herrmann, Z. Krist., 1926-1928. 148 C. R. Bailey,Trans. Paraclay SOC., 1930, 26, 203. la9 F. Hund, 2. Physik, 1925, 31, 81;1927, 43, 805.150 C. R. Bailey, A. B. D. Cassie, and W. R. Angus, Proc. Roy. SOC., 1930,130,133,142 ; W. W. Watson and A. E. Parker, Physical. Rev., 1931,37,1484.151 V. Henri and 0. R. Howell, Proc. Roy. SOC., 1930, 128, 178. 152 F.Matossi and H. Aderhold, 2. Physik, 1931, 68, 683. 153 W. H. Zachariasen,2. Krist., 1930, 73, 141. 154 H. C. Urey and H. Johnstone, Physical Rev.,1931, 38, 2131.120 A. Elliott, Proc. Roy. SOC., 1930, 127, 638.lZ2 G. E. Gibson and W. Heitler, ibid., 1928,49, 465.’140 A. Eucken, 2. Elektrochem., 1920, 26, 377.155 R. W. Wood, ibid., p. 2168.N. V. SIDGWICK.E. J. BOWEN

ISSN:0365-6217    

DOI:10.1039/AR9312800367

出版商:RSC    

年代:1931

数据来源: RSC

摘要:

INDEX OF AUTHORS’ NAMES.ABAEUDEOVSKI, 86.Abel, G., 58.Abeledo, C. A., 200.Abramson, H. A., 339, 340, 343, 350,Acharya, C. N., 249.Achterhof, M., 91.Ackermann, D., 162.Acree, S. F., 206.Adair, G. S., 232.Adams, E. T., 195.Ad-, J. M., 319.Adams, R., 78, 158.Adcock, F., 65.Aderhold, H., 284, 285, 403.Adhikari, G., 271.Adickes, F., 205.Adkins, H., 77, 81, 83, 84, 89.Adler, J., 315.Ageev, N. V., 313.Agte, A., 54.Agte, C., 59, 60, 63, 313.Ahmad, B., 222.Akim, L., 103.Alberola, L., 51.Albert, W. R., 254.Alder, K., 87, 125, 158, 159.Alexander, C. R., 135.Alexander, E., 283.Allan, J., 67.Allard, J., 182.Alldredge, S. M., 192.Allen, F. J., 49.Allen, W. F., 204.Allison, F., 181.AUmand, A. J., 39.Azmin, A,, 65, 315.Ahberg, C.L., 204.Alterthum, H., 59, 63, 313.Alty, T., 35, 340.Amadori, M., 76.Ambrose, P. M., 193.Amelink, J. F. H., 203.Aminoff, G., 267, 318.Amoy, L., 209.Anderegg, F. O., 357.Anderson, A. C., 205.Anderson, C. G., 98.Anderson, E., 253.hderson, H., 338.Anderson, M. S., 362, 363.351.Andress, K., 305, 328.Andrew, J. H., 65.Andrew, L. W., 137.Andrews, D. H., 371.Andrib, D., 252.Angell, F. G., 399.Angus, T. C., 212.Angus, W. R., 403.Anochin, W. L., 40.h l o w , W. K., 130.Applebey, M. R., 32, 54.Arbes, A., 52.hen&, B., 208.Aretissova, A. N., 260.Arkel, A. E. van, 265,273,313,339.Arm, M., 318.Armstrong, G. M., 252.Amot, F. L., 14.Arrhenius, S., 314.Arrivaut, G., 56.Asahins, Y., 150.-0, M., 143.Ascher, E., 55.Ashley, J.N., 161.Askew, F. A., 213, 214, 215, 216, 218.Astbury, W. T., 41, 231, 323, 324,326, 327, 328, 332.Aston, G. H., 16.Atanasiu, J. A,, 210.Ato, S., 189, 197.Atterer, M., 206.Audrieth, L. F., 53, 92.Auhagen, E., 146.Aulich, (F’rl.) M., 57.Auwers, K. von, 92.Avery, 0. T., 238.AZZOW, B., 202.Babaeva, A. V., 64, 201.Babcock, H. D., 403.Bach, T. N., 190.Badger, R. M., 403.Badhwar, I. C., 156.Baemtein, H. D., 207.BBuerlein, T., 317.Baggesgaard-Raamussen, H., 207.Bahl, D. C., 347.Bailey, C. R., 403.Baker, J. W., 110, 117, 118.Baker, W.. 156.40406 INDEX OF AUTHORS’ NAMES.Bakowski, S., 192.Balaban, I. E., 229.Balachovski, S., 196.Balkin, M., 342, 344, 348.Balser, G., 163.Bamann, E., 227.Bamberger, E., 137.Bamford, F., 202.Bancroft, W.D., 50.Banerjee, K., 286, 306, 384.Bannister, F. A., 318, 319.Barbieri, G. A., 58, 62.Barbot, A., 119.Bargellini, G., 147.Barger, G., 170, 234.Baril, 0. L., 202.Barker, E. F., 403.Barnard, M., 209.Barnes, E., 55.Barnes, W. H., 416.Barnett, E. deB., 113, 114, 129.Barrett, E. G. V., 209.Barta, F. A., 316.Barth, T. F. W., 300.Bartholomew, R. P., 243.Baruttschisky, I., 56.Basart, J. C. M., 314.Bassett, H., 57, 65.Batchelder, G., 199.Baudisch, O., 189.Bauer, K. H., 79, 80.Baumann, A., 359.Baver, L. D., 362.Bayliss, N. S., 129.Bechold, H., 180.Becker, J. A., 266.Becker, J. E., 256.Becker, K., 54, 59, 63, 313.Bedwell, W. L., 65.Behrend, R., 135.Behrens, W. U., 240.Bell, F., 118, 394.Bell, R.P., 30.Benary, E., 91.Bendger, W., 102.Bendien, S. G. T., 336.Benedetti-Pichler, A. A., 197, 200.Benesek, E., 193, 201.Bennett, G. M., 128, 129, 133, 134,Bennett, H. S., 341.Bennett, 0. G., 315.Bennett, R. D. 320.Benrath, A., 63Benson, W. L., 83.Bentivoglio, M., 276.Benton, A. F., 36,39.Berg, R., 193, 196, 201, 210.Berger, F., 171.Berger, R., 210.Bergkampf, E. S. von, 313.Bergmann, E., 112, 381, 302, 397.Bergmann, M., 90, 92, 98.138, 139.Bergmann, W., 145.Bed, E., 104.Bernal, J. D., 263, 292, 305.Bernauer, I?., 271.Berners, E., 100.Bernhauer, K., 126, 260, 361.Bernreuther, E., 91.Berry,A. J., 190.Bersch, H. W., 167Bersin, T., 189.Bertrand, G., 256.Beutler, W., 53.Bewilogua, L., 373, 374.Bey, L., 188.Beyer, F.C., 59.Bhaduri, D., 194.Bhagavantam, S., 284, 403.Bhatnagar, S. S., 347, 348.Bhattacharya, R., 80.Bhattacharyya, A. S., 337.Bhullar, A. S., 154.Biazzo, R., 200.Biczyk, J., 342, 345.Bijvoet, J. M., 296.Billiter, 341.Biltz, M., 338.Biltz, W., 56, 59, 60, 317.Bingham, E. C., 365.Birge, R. T., 375,402,403.Birke, J., 59.Birosel, D. M., 90.Biscoe, J., 318.Bishop, U. B. S., 247.Bjerrum, N., 370.Blackett, P. M. S., 14.Blake, F. C., 320.Blanchard, U. C., 84.Blanchon, H., 82.Bland, N., 111.Blank, E. W., 187.Blatchley, W. H., 204.Blechman, B., 90.Blenkinsop, A., 196.Bliss, H. H., 191.Blix, R., 318.Bloch, R., 51, 268, 315.Blood, P. T., 251.Bloom, J., 73Bluh, O., 338.Bobrhnski, B., 305.Bobtelsky, M., 199.Bock, L.H., 158.Bodea, C., 205.Bodenstein, M., 46.Bodforss, S., 340.Boedecker, F., 142.Boeseken, J., 79, 86.Bohm, J., 331.Boning, K., 257.Bottcher, F., 67.Bottger, W., 179, 188.Bohne, A,, 143.Boinot, G., 201,206INDEX OF AUTHORS’ NAMES. 407Boklund, U., 198.Bone, W. A., 54.Bonhoeffer, K. F., 35, 378.Bonner, W. D., 194.Bonthron, K. J. A., 64.Boord, C. E., 91.Booth, H. S., 52.Born, M., 23.Borsche, W., 142.Bosch, E. X., 304.Bose, A. C., 146.Bose, P. K., 203.Bott, H. G., 95.Bouchonnet, 103.Bougault, J., 200, 203.Bourdillon, R. B., 213, 215, 216, 218.Bourguet, M., 182.Bousfield, W., 33.Boutaric, A., 346.Bowden, R. C., 338.Bowen, E.G., 315.Bowen, E. J., 43.Bowen, N. L., 63,64, 319.Bowers, A. D., 193.Bowers, H. E., 372.Boxer, S. E., 84.Bradfield, A. E., 116.Bradfield, R., 353, 355, 361.Bradley, A. J., 294, 314.Bradley, W., 80.Brady, 0. L., 193, 201.Briikken, H., 296, 297, 315.Bragg, (Sir) W. H., 306, 373.Bragg, W. L., 300, 301,318,334,373.Brand, 289.Brandenberger, E., 300, 319.Brantley, L. R., 314.Brathuhn, G., 77.Braun, G., 99.Braun, W., 174.Brauns, F., 101.Breazeale, J. F., 240.Brecher, C., 205.Breckpot, R., 94.Bredereck, H., 206.Bredig, G., 313.Bredig, M. A., 319, 320.Bredt, J., 143.Brennecke, E., 210.Brenneis, H. J., 209.Bretschneider, O., 313.Brewer, F. M., 51, 130.Bridel, M., 254.Bridgman, P. W., 270.Briegleb, G., 319.Briggs, D.R., 343, 345, 349.Briggs, G. E., 239.Briggs, T. R., 341.Bright, H. A., 196.Brill, R., 316,319, 320,329, 331.Brindley, W. H., 169.Brings, T., 268.Brintzinger, H., 193.Briscoe, H. V. A., GO.Brissand, 298.Britton, H. T. S., 53, 58, 185, 191.Brockmann, R., 220.Broderick, S. J., 65, 315.Brodkorb, F., 398.Bronsted, J. N., 136.Brown, D. J., 193.Brown, F. S., 135.Brown, S. M., 353.Bruce, H. M., 213, 214, 215.Bruchhausen, F. von, 167.Bruckner, Z . , 99.Briicher, H., 237.Bruckl, K., 307, 319.Bruckner, A., 317.Briinger, K., 60, 190.Briining, G. von, 91.Bruin, P., 27, 50.Bruins, H. R., 221, 223.Brunauer, S., 314.Bruni, G., 320.Brunken, J., 145.Brunnert, W., 205.Bruylants, P., 94.Bryant, S. A., 160.Buchan, S., 119.Bucherer, H.T., 122, 193, 200.Buckley, H. E., 275, 316.Buckwalter, H. M., 205.Budge, P. M., 314.Buche, K., 191.Buehler, C. A., 134, 136.Buerger, M. J., 295.Bussem, W., 316.Bujor, D. J., 316, 318.Bulgrin, W., 56.Bull, H. B., 348.Bungenberg de Jong, H. G., 348.Bunting, E. N., 62, 64, 319.Burch, W. J. N.,.90.Burgeni, A., 321, 328.Burgers, W. G., 273, 313, 314, 316.Burgess, 256.Burkhardt, G. N., 66.Burns, A. C., 122.Burrage, L. J., 39.Bursian, V., 47.Burstall, F. H., 49, 52, 61, 132, 157,Burton, E. F., 336, 337, 341.Burton, H., 106, 114, 115.Buschendorf, F., 276, 317.Busse, P., 219.Butenandt, A,, 236, 237.Butler, A. M., 196.Butte, H., 145.Buztigh, A. von, 345, 346.Byrd, R. M., 196.398.Cabanes, E., 260.CabaGes, J., 286408 INDEX OFCaglioti, V., S6, 58, 63, 315.Cairns, R.W., 316.Caley, E. R., 196, 197.Calfee, R. K., 259.Callow, R. K., 144, 213, 214, 215.Calvert, F., 106.Canals, E., 250.Canay6, J., 250.Canter, F. W., 155.Capuchino, A. S., 211.Casares, J., 192.Casares, R., 192.Casazza, E., 319.Caspari, W. A., 320.Cassel, H., 34.Cassie, A. B. D., 403.Castell, R. A. S., 132.Cattelain, E., 193, 200.Cavallini, A., 315.Cavell, H. J., 131.Celsi, S. A., 202.Cerchez, V., 90, 201.Chablay, E., 184.Chakravarti, D., 155.Challenger, F., 261.Challinor, S. W., 98.Chalmeta, A., 204.Champetier, G., 104.Champion, F. C., 14.Chang, C., 158.Chapman, D. L., 45.Charaux, C., 254.Charles, A. F., 233.Charonnat, R., 61.Chase, E.F., 191.Chatron, M., 200, 208.Chattopadhya, A. K., 194.Chaudhury, S. G., 346, 347.Cherbuliez, E., 134.Cheymol, J., 252.Chikashige, M., 315.Child, R., 169.Christian, B. C., 206.Christman, C. C., 96.Chrobak, L., 317.Chrzaszcz, T., 261.Chu, E. J. H., 201.Cimerman, C., 192.Clar, E., 125, 126, 127.Clark, 0. E., 186.Clark, R. E. D., 56.Clarke, B. L., 184.Clarke, L., 197.Clarke, R. H., 70.Clarke, S. G., 194.Cleeton, C. E., 403.Clemmensen, 141.Clemo, G. R., 160, 174, 175, 176.Clermont, J., 183.Clifford, C. W., 184.Cloes, J. O., 256.Clouse, J. H., 316.Clark, G-. L., 320.AUTHORS’ NAMES.Clusius, K., 28, 49.Cochet, A., 52.Cocker, W., 65, 84, 89, 90.Cocks, L. V., 206.Coehn, A., 336.Coghill, R.D., 207.Cohen, E., 26, 50.Cohen-de Meester, WT. A. T., 26,Cohn, W. M., 316.Colby, M. Y., 316.Colin, H., 101.Colla, C., 64, 315, 316, 317.Colles, W. M., 52, 133.Collin, E. M., 209.Collins, G. B., 209.Collins, G. W., 196.Colmant, P., 94.Columbier, L., 203.Comber, N. M., 243, 364.Compton, K. G., 184, 210.Conaway, R. F., 91.Connor, R., 83.Cook, J. W., 113, 114, 126, 127.Cooper, B. S., 319.Cooper, K. E., 110.Cooper, W. C., 250.Corey, R., 317.Cork, J. M., 316.Cornec, E., 63.Corneli, W., 233.Corson, B. B., 83.Cotton, M., 246.Cottrell, F. G., 277.Coulson, E. A., 126.Courtois, J., 199.cousin, 199.Coward, (Miss) K. H., 224.Cowperthwaite, I. A., 210.Cox, E. G., 305.Cox, R. F. B., 201.Cope, 234.Cramer, H., 83.Craven, R., 202.Creed, R.H., 224.Cremer, E., 5.5.Cremer, H. W., 55, 59.Crepaz, E., 64.Cross, H. C., 314.Crossley, F., 202.Crowther, E. M., 366.Cucuel, F., 194.Cucuelescu, V., 207.Cugnac, A., 255.Cuny, L., 193.Curd, F. H., 155.Currie, B. W., 340, 350.Currie, J. E., 341.Curtis, L. F., 266.Curtius, T., 90, 91.Cutliffe, E. F., 131.Cuvelier, V., 63.Czak6, E., 205.50INDEX OF AUTHORS’ NUES. 409Czaporowski, L., 210.Czerny, M., 369.Dabrowska, O., 243.Dadieu, A., 371.Dadswell, H. E., 254.Daft, F. S., 207.Dabs, F. B., 184.Dakin, H. D., 230, 235.Dale, (Sir) H. H., 213, 215.Damianovich, H., 314.Daniel, W., 199.Daoud, K. M., 102.Daa, R., 63.Das-Gupta, P. N., 193.Das-Gupta, T., 61.Dame, P., 182, 403.Davey, W.P., 314, 317.David, L., 189, 207.Davidson, J., 254.Davidson, J. M., 197.Davidson, P. M., 402.Davies, D. R., 205.Davies, E. A., 241.Davies, J. S. H., 122.Davies, P. A., 251.Davies, W. C., 205.Davis, H., 343.Davis, L. D., 252.De Boer,’J. H., 265.Debye, P., 350, 373, 374, 379.De Carli, F., 134.De Celis, M. G., 189, 208.De Celsi, M. N. A., 202.Dhcombe, J., 90.De Cori, P., 208.De Haan, E. F., 349.De Haas, G., 202.De Haas, W. J., 52, 315.Dehlinger, U., 273, 292, 293.De Jong, W. F., 315, 317.De Kadt, G. S., 340.De la Roche, B., 209.Delbriick, M., 14.Del Campo, A., 200, 208.Denham, H. G., 64.Denigbs, G., 200, 203, 207.Dennis, L. M., 58.De Paolini, I., 202.Deppe, M., 215.Derlon, H., 91.De Sadaba, R., 189.Deschaseaux, R., 196.De Smedt, J., 319.De Sornay, P., 246.Deulofeu, V., 141, 142.Deutsch, D., 337.Devoto, G., 62.De Vries, O., 392.Dhar, N.R., 65, 348.Dick, D. A., 64.Dick, J., 191.Dickinson, R. G., 398, 403.Diebold, W., 91.Diehm, R. A., 253.Dieke, G. H., 403.Diels, O., 125, 144, 158, 159.Dietz, E. M., 127.Dijatschkovski, S. I., 188.Dikussar, I. G., 242.Dillon, R. T., 403.Dilthey, W., 139.Dimroth, O., 137.Dithmar, K., 145.Dittler, E., 192.Dittmar, H. R., 133.Dittrich, W., 250.Ditz, H., 199.Dixon, B. E., 62.Dixon, J. K., 38.Djelatides, D., 196.Dobbins, J. T., 65, 195, 196.Doby, G. von, 259.Dodd, E. N., 185, 191.Doring, T., 197.Doerner, H. A., 197.Don, W., 91.Dogane, G., 65.Dohse, H., 38.Doisy, E.A., 236.Dolch, M., 191.Dole, M., 32, 33.Dominikiewicz, M., 200.Domontovitsch, M. K., 241.Donovan, J. E., 63.Doran, W., 146.Dore, W. H., 320, 322.Dorn, 341.Dornte, R. W., 388, 391.Dorrington, B. J. F., 195.Downes, H. C., 211.Dbzsa, A., 195.Drake, N. L., 81.Drew, H. D. K., 100, 398, 399.Dreyer, K. L., 273.Druce, J. G. F., 243.Drummond, J. C., 220.Dubsk9, J. V., 189.Ducloux, E. H., 210.Dudley, H. W., 229, 230.Diill, H., 85.Diirr, W., 254.Dufford, R. T., 403.Dufour, 199.Duisberg, H., 92.Dullenkopf, W., 51.Dumanski, A. V., 337.Dumont, P., 208.Dunbar, C., 124, 318.Dulncan, D. R., 55,59.Duninowski, A. I., 208.Dunlap, A. A,, 257.D u n , M. S., 90.Dunn, R. T., 94.Dunnicliffe, H.B., 56410 INDEX OF AUTHORS' NAMES.Dupont, G., 182.Durrant, P. J., 63.Durrant, P. T., 190.Durrant, R. G., 57.Durrer, R., 64.Duval, C., 61.Duval, (Mme.), 61.Du Vigneaud, V., 92.Dvorzak, R., 196.Dyer, F. J., 224.Dzieworiski, K., 120, 126.Eaton, F. M., 245.Ebermayer, G., 85, 88.Ebert, F., 63, 313, 315.Ebert, G., 56.Ebert, L., 395.Eckerson, S. H., 244.Eckert, T. S., 276.Eckling, K., 335.Eckman, W., 294.Eckstein, O., 246.Edwards, C. A., 65.Edwards, D. A., 316.Eegriwe, E., 189.Effront, J., 102.Efremov, N. N., 135.Egg, C., 198.Ehrenberg, H., 319.Ehrenberg, R., 208.Ehrenberg, W., 384.Ehret, W. F., 65, 315.Ehrhardt, F., 373.Eigenberger, E., 72.Eisenbrand, J., 204.Eisenhut, O., 313, 314.Eisenschitz, R., 395.Eissner, W., 320.Eitel, W., 318.Ekkert, L., 202, 203.Ekman, W., 314.Elam, (Miss) C.F., 266, 314.Elben, E., 61.Elema, B., 191.Elleder, H., 245.Elliott, A., 403.Elliott, K. A. C., 394.Ellis, B. A., 211.Ellis, C. D., 15, 16.Ellis, R., 339.Elmquist, (Miss) R., 54, 198.Emmert, E. M., 198.Emmett, P. H., 314.EndrBdy, A. von, 200.Engel, L., 336, 338, 381, 392, 397.Engel, R., 67.Enger, R., 90.Enk, E., 60.Ephraim, F., 193.Epstein, S., 314.Erdheim, E., 193, 201.Ergle, D. R., 122.Erickaon, J. L. E., 82.Ermann, E., 80.Ernould, L., 94.Errera, J., 130, 392, 394.Ertel, L., 143.Erxleben, H., 92.Essin, O., 58.Estermann, I., 266, 381, 395.Ettisch, G., 337, 342, 347, 351.Eucken, A,, 386, 388, 403.Euler, H.von, 131, 220, 222.Eulitz, W., 304.Evans, B. S., 194, 199.Evans, M. G., 38, 319.Everest, A. E., 119.Everet, J., 61.Evrard, V., 63.Ewald, J. W., 403.Ewald, P. P., 262, 263.Ewald, R. F. A., 61.Ewing, D. T., 210Eyring, H., 21.Fagan, T. W., 252.Fain, R., 200.Fairbrother, F., 340, 341, 342, 344,345, 346, 348.Fairbrother, T. R., 192.Fajans, K., 386.Falkenhagen, H., 33.Faltin, E., 208.Farkas, A., 35, 378.Farkass, E., 203.Farmer, E. H., 73, 74.Farmer, R. C., 104.Farnsworth, (Miss) M., 403.Fedulov, N. S., 189.Fehdr, E., 259.Feher, F., 59.Fehse, W., 265, 266.Feigl, F., 188, 189, 190, 192, 202.Feist, F., 105, 111.Feit, W., 60.Feitknecht, W., 317.Feld, E., 90.Feldstein, P., 189.Fellenberg, T, von, 245, 246.Fenimore, E.P., 193.Fenton, H. J. H., 77.Ferguson, G. E., 198.Ferner, G. W., 186.Ferrari, A., 64, 315, 316, 317, 319,Ficklen, J. B., 196.Field, M. J., 138.Fierz-David, H. E., 127.Fieser, L. F., 127.Fikentscher, H., 326.Filimonovitsch, K. M., 189.Fine, R. D., 315.Finzenhagen, H., 87.Fischer, F. G., 85.320INDEX OF AUTHORS’ NAMES. 41 1Fischer, H., 188, 191.Fischer, J., 196.Fischmann, C., 213.Fisher, (Miss) N. I., 163.Fiske, C. H., 195.Fitch, A. A., 183.Flaschentrager, B., 90.Fleeson, E. H., 342, 346.Fleischer, J., 64.Fleury, P., 199.Flink, W. L., 314.Fodimann, E. B., 346.Foerster, F., 57.Fogelberg, J. M., 394.Folkers, K., 77.Fonda, G. R., 209.Foote, H. W., 64.Foote, M. E., 200.Forestier, H., 317Forestier, J., 304.Forgeng, W. D., 63.Forsee, W.T., 189.Fosbinder, R. J., 191.Foster, G. L., 234.Foster, R. L., 211.Fowler, E. A., 65.Fowler, R. H., 15, 16.Fox, J. J., 211.Fox, J. M. C., 131.Frahm, E. D. G., 70.France, W. G., 276.Francis, F., 320.Franck, H. H., 52.Franck, J., 23.Franqois, M., 202, 208.Frank, G. O., 316.Franke, W., 77.Franquin, 2 1 0.Franzen, H., 121.Freedericksz, V., 283.Frenzel, A., 306.Frerichs, R., 402.Fresenius, L., 192.Freudenberg, K., 94, 254.Freudenberg, W., 98.Freundlich, H., 335,342,343,345,349.Frey, A., 261, 324.Frey, H., 57.Freymann, R., 181.Frey-Wyssling, A., 324.Fridli, R., 198.Friedel, E., 280.Friedel, G., 279, 280.Friedel, M. G., 317.Friederich, P., 348.Friedrich, A., 204.Friend, J.A. N., 54.Fries, K., 121.Fritzmann, E., 62.Frohlich, K. W., 65.Frost, A., 56.Frost, A. V., 70, 199, 320.Frumkin, A., 340.Fry, H. S., 86.Fuchs, N., 305.Fuchs, O., 192, 395.Fiirth, R., 337.Fujita, A., 199.Fulmer, E. I., 193, 211.Fulton, C. C., 203.Funk, H., 192.Funke, G., 315.Furman, N. H., 192, 209, 210.Furter, M., 204.Furukawa, S., 149.Fuss, V., 64.Gable, H. S., 55.Gaddum, J. H., 224.Gaede, J., 146.Gadke, W., 144.Gaertner, H. R. von, 300.Gallafent, V., 51.Gamble, E. L., 54.Gamow, G., 24.Ganesan, A. S., 370.Gans, R., 357.Ganssen, R., 356.Garcia Ban&, A., 106.Gardner, H., 203.Garner, W. E., 38, 138.Garrick, F. J., 298.Garrison, A., 340.Gaus, W., 246.Gauter, F., 331.Gaviola, E., 378.Gazewski, H., 373.Gebauer-Fulnegg, E., 92, 122, 202.Gebhardt, F., 90.Geddes, R.L., 43.Gedroiz, K. K., 358, 362.Gee, N., 319.Geffcken, W., 29.Gehlen, H., 56.Gehrke, M., 98.Geilmann, W., 51, 60, 187, 190, 201.Gelbach, R. W., 210.Genaud, P., 250.Gerasimov, J., 64.Gerecs, A., 99.Gerhard, S. L., 316.Gericke, P. H., 167.Gerlach, K., 85, 88.Gerlach, W., 209.German, W. L., 58.Germann, F. E. E., 64.Gerstner, F., 194.Ghosh, B., 346.Ghosh, S., 348.Gibbs, F. B., 45.Gibson, C. S., 52, 133.Gibson, G. E., 403.Giese, H., 55.Gilbert, B. E., 256.Gilbert, F. L., 398412 INDEX OF AUTHORS’ NAMES.Gilchrist, R., 198.Gillam, A. E., 224.Gillbe, H. F., 138.Gilman, H., 115.Ginsberg, H., 197, 199.Giorgi, F., 315.Girardet, A., 170.Glauner, R., 130.Gleu, K., 200.Glixelli, J., 346.Gnesin, V.D., 203.Go, J., 171.Goebel, W. I?., 238.Goehler, 0. E., 192.Gorlacher, H., 209.Goetz, A., 268, 271.Gotze, J., 164.Goldberg, A. A., 108, 127.Goldschmidt, S., 122.Goldschmidt, V. M., 286, 289, 301,303, 373, 383, 403.Golse, J., 193, 198.Gonell, H. W., 329.Goodall, E., 136.Gooderham, W. J., 44.Goodway, N. F., 114.Goodwin, T. T., 83.Gootz, R., 99.Gbrski, M., 243.Gortner, R. A., 343, 344, 348.Gorton, J., 143.Gossner, B., 316, 317, 318, 319.Goto, M., 65.Gottfried, C., 300, 317.Goubeau, J., 51.Goudet, H., 125.Gough, G. A. C., 143, 166.Gould, L. P., 50.Gouveia, A. J. de A., 209.Gouy, M., 350.Govaert, F., 205.Grace, N.S., 50, 317.Graf, L., 268, 270.Grassner, F., 192.Graves, G. H., 320.Gray, I(. R., 70.Green, J., 258.Greenbaum, F. R., 131.Greene, H. S., 191.Greenwood, G., 318, 320.Greer, (Miss) E. J., 27.Greger, J., 256.Gregory, C. H., 294.Greig, M. E., 96.Griebel, C., 190.Griessbach, R., 246.Griflfing, E. P., 204.G f i t h s , J. G. A., 46.Grignard, V., 82.Grigoriev, P. N., 196.Grimm, H. G., 386.Grinten, K. van der, 339, 350.Groesbeck, E. C., 314.Gr6h, G., 208.Groschenkov, A. I., 241.Gross, H., 54.Grosscup, C. G., 55.Grosskopf, W., 144.Grossman, E. B., 351.Grove, (Miss) K. E., 152.Groves, R., 55.Griinberg, A. A., 62.Griineisen, 32.Gruner, J. W., 295.Gunther, P., 209, 316.Guillemin, V., 395.Guillon, J., 203.Guillot, M., 67, 198.Gulati, K.C., 155.Gulland, 6. M., 172.Gully, U., 359.Gump, W., 119.Gupta, R. S., 348.Guzzoni, G., 209.Gyemant, A., 341.Haas, A. R. C., 244, 245, 257.Haase, R., 398.Hackspill, L., 50, 298.Hligg, G., 293, 314, 315.Hagen, S. K., 200.Hahn, F. L., 190, 196, 199, 209.Halban, H. von, 135.Haldane, J. B. S., 225.Hale, J. B., 78.Halford, J. O., 187.Hall, F. P., 365.Halla, F., 209, 304, 315,317 319,321.Halle, F., 90.Hallonquist, E. G., 70.Hamasumi, M., 64, 314.Hambsch, O., 91.Hamburg, H., 189.Hamer, (Miss) F. M., 163, 164.Hamid, M. A., 63.Hammick, D. L., 117, 137, 392, 393.Hampson, J., 137.Hand, D. B., 226.Handovsky, H., 161.Hanke, E,, 55.Hann, A. C. O., 83.Hansen, H., 319.Hantzsch, A., 93, 398.Harang, L., 297.Harder, A., 51, 295.Harding, G., 206.Hardy, F., 364.Hardy, (Sir) W., 34.Haring, M.M., 195.Harington, C. R., 161, 234.Harkins, W. D., 372.Harlow, W. M., 254.Harper, E. M., 137.Harral, J. C., 205.Harries, 86INDEX OF AUTHORS’ NAMES. 413aH aaHElaHHaBI3Iarris, J. A., 248.;arris, L. J., 219.hrris, S. A., 115.:amison, F. C., 114.Lamison, G. B., 191.:artel, H. von, 47, 395.hrtley, (Sir) H., 29, 34.!artmaan, H., 313.,artFg, W. H., 202..artmg, H., 318.:arvey, J., 119.:aschimoto, U., 62, 315.Haakelberg,-L., -90..Haslewood, G. A. D., 237Hassel, O., 306, 316, 317, 319.Hasselbring, H., 2.55.Hatcher, W. H., 86.Hatsuta, K., 64, 314.Hattori, S., 148, 149, 154.Haught, 5.W., 198.Haughton, J. L., 313.Haworth, W. N., 94, 95, 96, 98, 99,100, 102, 105, 322.Hawran, B., 127.Hayashi, K., 154.Head, F. S. H., 87, 147.Heap, A. G., 135.Hebler, F., 180.Hecht, 55.Heckel, H., 56.Hedvall, J. A., 319.Heidelberger, M., 239.Heilborn, H., 61.Heilbron, I. M., 72, 119, 120, 144,Heim, G., 94.Heimann, H., 52.Hein, F., 199.Heinerth, E., 56.Heisenberg, W., 367.Heitler, W., 14, 17, 403.Helberger, J. H., 226.Helfenstein, A., 71, 153, 220.Helferich, B., 99, 102.Heller, G., 119.Heller, K., 243.Hellstrom, H., 220, 222, 225.Helmholtz, H. von, 244.Helwig, G. V., 316.Hendricks, S. B., 291, 293, 294, 304,313, 314, 395, 397.Hendry, (Miss) C. B., 155.Hengstenberg, J., 305, 332, 384.Hemi, V., 395, 403.Henry, D.C., 339, 340, 350.Hensel, W. G., 100.Hepburn, H. C., 342, 345.Hepburn, J. S., 203.Herlinger, E., 289.Hermann, C., 262, 263, 283.Hermann, K., 282, 316, 403.Herndlhofer, E., 203.Hernler, F., 198, 204.145, 146, 156, 223, 224.Herrlin, A., 317.Hem-, K., 283, 297, 316.Hem-, Z., 52, 317.Hersant, E. F., 95.Hertel, E., 46, 132, 139, 306, 307,Hertel, W., 193.Hertzog, R. O., 254.Herviaux, J., 246.Henberg, G., 375, 402.Herzner, R. A., 196.Henog, R. O., 323, 327, 328, 332.Hess, K., 103, 328, 329.Hess, W. C., 207.Hesse, G., 161.Hesser, W. F., 82.Hevesy, G. von, 55.Hewett, C. L., 114.Hey, J. S., 318.Heyden, E. von, 207.Heme, G., 54, 59, 197, 313,Heyrovak3, J., 209.Heyworth, D., 315.Hezel, E., 75.Hibben, J.H., 44.Hibbert, H., 96, 98, 101.Hickinbottom, W. J., 99.Hieber, W., 60, 132.Hieger, I., 127.High, M. E., 372.Hildebrandt, F., 236,237.Hilditch, T. P., 78, 79, 205.Hill, A. E., 63.Hill, D. W., 166.Hillmar, A., 254.Himmat, M. A., 124.Hinderer, W., 188.Hinshelwood, C. N., 43.Hinkel, L. E., 94.Hirata, M., 315.Hirsch, H., 177.Hisey, A., 135.JEIissmk, D. J., 355.Hitchen, C. S., 182, 209.Hitz, F., 85.Hoagland, D. R., 240.Hoar, T. P., 64.Hoard, J. L., 315.Hocart, R., 317.Hock, L., 327.Hodges, J. H., 44.Hodgson, H. H., 129, 202.Holemann, H., 209.Holtje, R., 56, 194.Holzl, G., 133.Hoevera, R., 79.Hoffman, J. I., 196.Hoffmrt~, c., 94.Hofmann, U., 306.Hofmann, W., 298, 317.Holch, H., 56.Holden, N.E., 71.320, 321.E. L., 94, 95, 96, 98, 105414 INDEX OF AUTHORS’ NAMES.Holder, G., 210.Holgersson, S., 317.Holleman, A. F., 135.Hollidav. G. C.. 44.Holsch&der, F. W., 174, 176.Holt, M. L., 210.Holwerda, B. J., 348.Hope, E., 83, 166.Hopkins, B. S., 53.Hopkins, E. F., 247.Hoppe-Seyler, F. A., 162.Home, W. D., 337.Hosking, J. R., 120.Hosoda, T., 90.Hougardy, H., 64.Hough, W. A., 196.Houtz, R. C., 89.Hovorka, V., 200.Howat, D., 65.Howell, 0. R., 403.Howells, E. V., 315.Howitt, F. O., 336, 343.Hoyem, A. G., 268,270.Hudson, L., 74.Hueber, H., 192.Huckel, E., 17, 18, 19, 350, 367.Hiihn, W., 62.Hurliman, W., 153.Huther, F., 75.Huttig, G. F., 52, 56, 60, 64, 317.Huggins, M.L., 316, 319, 395.Hugh, W. E., 109.Hull, A. W., 373.Hulme, A. C., 206.Hume-Rothery, W., 289, 294, 384.Humme, H., 53.Hummitzsch, W., 62.Humphrey, R. H., 340, 348.Hund, F., 14, 17, 403.Hunter, G., 202.Huppmann, G., 207.Husser, R. C., 104.Hutton, J. C., 50.Ilge, W., 297, 316.Illingworth, W. S., 393.Ing, H. R., 176.Ingalls, R. A., 248.Inganni, A., 64, 315.Ingold, C. K., 67, 69, 70, 73, 74, 105,Ingold, C. T., 249.Ingold, E. H., 67.Innes, J. R. M., 219.Inoue, Y., 78, 79.Intonti, R., 193.Inubuse, M., 150.Ionesco-Matiu, A., 200, 207.Ionescu, V., 205.Ipatiev, V. N., 56, 317.Ipatiev, V. V., jun., 50.Irvine, (Sir) J. C., 100.106, 110, 112, 116, 394.Isaenko, T. I., 188.Isbell, H. S., 52, 95, 96.Ishibashi, M., 200.Ishimasa, M., 165.Ishiwara, T., 63, 314.Ishiwata, S., 172.Ito, T., 289.Ivanitzkaja, A., 345.Ivanov, N.N., 260.Ives, D. J. G., 51.Iwata, S., 147.Jackson, R. F., 100.Jackson, R. W., 161.Jackson, W. W., 302.Jacobson, C. A., 198.Jacquet, 103.Jacubowicz, L., 175.Jaeger, F. M., 313, 319.Jakdb, W. F., 58.James, L. H., 195.Jameson, E., 233.Jancke, W., 322, 327, 328.Jander, G., 210.Jander, W., 57.Jane, R. S., 340, 348.Janek, A., 337.Janssen, G., 243.Janssen, L. W., 336.Javillier, M., 196.Jefferson, M. E., 314.Jenny, H., 356, 358.Jensen, B. N., 205.Jeppesen, C. R., 403.Jessop, G., 57, 401.Jette, E. R., 337.Jezowska, B., 58.Jilek, A., 194, 195, 197.Joff6, A., 320.Johannson, C. H., 293.Johansson, H., 318.John, F., 127.Johnson, A.H., 258.Johnson, C. R., 180.Johnson, E. S., 244.Johnson, J. R., 118, 202.Johnson, T. B., 91.Johnson, W. C., 55.Johnstone, F., 145.Johnstone, H., 403.Jones, B., 116.Jones, D. B., 207.Jones, D. C., 133.Jones, G., 32.Jones, I. D., 248.Jones, L. W., 90.Jones, P., 314.Jones, W. M., 315.Jones, W. O., 116.Jones, W. R. D., 65.Joseph, A. F., 361.Josephson, K., 96INDEX OF AUTHORS’ NAMES. 41 5Jost, W., 44, 378.Jovinet, P. L., 137.Joy, W. C., 33.Jukkola, E. E., 53.Jung, H., 319.Jurenka, W., 199.Jurriaanse, F., 52, 315.JUZB, I. R., 60.Kabraji, K. J., 817.Kalberer, W., 38.Kastner, F., 318, 319.Kahane, C., 201,206.Kahane, (Mme.) M., 201, 206.Kahlenberg, L., 210, 256.Kallir, P., 147.Kam, E.J. van der, 120.Kameda, T., 191, 210.Kamm, E. D., 72.Kapitza, P., 266, 269, 270.Kaplan, J., 402.Kapsulitzas, H. J., 188.Karaoglanov, Z., 191.Karashima, J., 90.Karasiliski, M., 199.Karrer, P., 72, 89, 150, 153, 174, 175,Karstens, A., 144.Kasansky, B., 206.Kasper, C., 292.Kassler, R., 317.Kast, W., 282, 283.Katoh, N., 314, 315.Katsurai, T., 316.Katz, J. R., 325.Kaupp, E., 313, 314.Kay, F. W., 112.Keenan, G. L., 201,203.Keenen, F. G., 276.Keesom, W. H., 28,29,298,319.Keil, A. W., 162.Keil, F., 90.Keil, W., 162.Kelland, N. S., 47.Kelley, V. W., 258.Kelley, W. P., 353.Kelly, (Mrs.) M. I., 164.Kelly, T. L., 209.Kendall, F. E., 239.Kenner, J., 138.Kenyon, J., 118, 394.Kermack, W.O., 351.Kerr, H W., 357.Kerr, P. F., 318.Kershaw, A., 129.Kelians, A., 200.Keseling, J., 260.Ketelaar, J. A. A., 316.Kettering, C. F., 371.Keunecke, E., 314.Keyes, D. B.; 70.Keys, A. B., 199.219, 220, 221, 222, 223.Kharasch, M. S., 52.Kidson, J. O., 64.Kieffer, A. P., 298.Kilpatrick, M., jun., 191.King, A. M., 348.King, E. J., 98.King, F. E., 154, 255.King, H., 90, 130, 166, 220.King, R. B., 39.Kingman, F. E. T., 38.Kirzon, B., 205.Kishen, J., 56.Kistiakowski, W., 129.Kistiakowsky, G. B., 40, 45.Kitasato, Z., 173.Kittelmann, (Frl.) C., 53.Klages, F., 105.Klatschin, N., 204.Kleeman, R. D., 341.Klein, D. L., 84.Klein, G., 203.Klein, L., 261.Weist, W., 164.Klemen, R., 252.Klenk, E., 91.Kleu, H., 320.Klever, E., 317.Kline, G.M., 206.Kline, L., 203.Klockmann, R., 209.Klotz, L. J., 244, 257.Klug, H. P., 320.Knaggs, (Miss) I. E., 306, 395.Knapp, B., 74.Kneuer, A., 176.Kniga, A. G., 337.Knop, J., 191, 194.Kobayashi, R., 320.Kobosew, N. I., 40.Koch, E. M., 144.Koch, F. C., 144.Koch, H. J., 201.Koch, W. W., 192.Kodama, T., 199.Kogl, F., 92.Koelsch, C. F., 201.Konig, A., 317.Konig, W., 164.Ktippen, R., 60,317.Korber, F., 315.Koser, J., 146.Koster, W., 64.Kojszegi, D., 193..Kohler, E. P., 82, 110.Kohlrausch, K. W. F., 370, 371, 403.Kohlschutter, H. W., 89.Kohlschutter, V., 53, 317.Kolitscheva, N. N., 199.Kolkmeijer, N. H., 315.Kolnitz, H., von, 199.Kolthoff, I. M., 54, 179, 189, 191, 194,Komaretsky, S., 193.198, 200, 210416 INDEX OF AUTHORS’ NAMES.Kon, G.A. R., 108, 109, 110, 111.Konctrzewski, J., 64.Kondo, H., 170, 172.Kondoguri, W., 268.KondratBev, V., 402.Kording, P., 144.Koref, F., 265.Korenman, I. M., 188.Kornfeld, (Frl) G., 356, 357.Korol, S. S., 196.Korvezee, (Mlle) A. E., 51, 57.Koschara, W., 165.Kossel, W., 276.Kostelitz, C., 317.Kosthg, P. B., 293.KO&, J., 197.Kotovski, A., 53, 205, 209.KovaE, D., 65.Kozak, J., 163.Kracek, F. C., 63, 64, 291, 316, 319.Kraineck, H. G., 204.Krallis, M., 79.Krastelevskaja, S. A., 133.Kratky, O., 321, 328, 329, 335.Krause, H., 90.Krauss, E. von, 89.Krauss, F., 60, 188, 398.Kraut, H., 53, 54.Kraybill, H. R., 251.Krejci, L., 316.Kremer, A., 86.Kreulen, D.J. W., 206.Krieger, P., 316.Kringstad, H., 306,316,319.Krisch, M., 203.Krishna, R., 135.Krkhna, S., 135.Krkhnamurti, P., 284.Krishnan, K. S., 370.lG%, A., 63.Kronig, R. de L., 14.Kruber, O., 119.Kriiger, A,, 191.Krueger, A. P., 337.Kruger, D., 202, 332.Krumholz, P., 190.Krummacher, A. H., 282.Kruyt, H. R., 335,336, 337,339, 340,Ksanda, C. J., 316.Kubelkovit, O., 194.Kubina, H., 200.Kiirschner, 0. H., 78.Kiistenmacher, H., 193.Kuffner, F., 167, 168, 179.Kuhn, R., 163, 219, 220, 222, 305,Kuhn, W., 268.Kuleliew, K., 275.Kundu, P., 342, 345, 346.Kunitz, M., 226, 339.Kunitz, W., 318.Kurbatov, I., 276.342, 345, 346, 347, 348, 349.403.Kurdjumov, G., 293.Kurilov, B. B., 135.Kuriyama, S., 329.Kurnakov, N. S., 313.Kurtenacker, A., 199, 200.Kurtz, F., 195.Kutz, W.M., 81.Kurzyniec, E., 64.Laass, E., 270.Labrousse, F., 259.Lachs, H., 342, 345.Laing, (Miss) M. E., 186.La Mer, V. K., 211.Lang, R., 194, 195.Langauer, D., 64.Lange, E., 210.Lange, L., 392.Laager, R. M., 14.Lantz, E. A., 340.Lantz, R., 122.Lapworth, A., 67, 71, 72, 83, 84, 89,90, 107, 110, 116, 118.Laschkarev, V. E., 315.La Tour, F. D., 75, 305.Laue, M. von, 331.Lautenschlager, L., 89.Lavaux, J., 126.Laves, F., 289.Lawrence, C. D., 74.Lazarchick, M., 203.Leach, W., 248.Leake, C. D., 202.Leather, A. N., 204.Leatherman, M., 195.Leavenworth, C. S., 92.Le Blanc, M., 275, 315.Lederer, E., 220.Lee, H. A., 247.Leermakers, J.A., 43.Le FBvre, R. J. W., 117.Lehl, H., 53, 209.Lehmann, G., 198.Lehmann, O., 206.Leighton, P. A., 209.Leimbach, G., 62.Leitch, G. C., 99, 176.Leithe, W., 173.Leitmeier, H., 189, 190.Lemarchands, M., 54.Lematte, L., 201, 206.Lemke, A., 317.Lemon, H. B., 144.Lenel, F. V., 305, 320.Lenher, S., 26.Lennard.Jones, J. E., 14.Leon, A., 152, 153.Leroux, J. A. A., 65.Lespieau, R., 182.Leu, A., 379.Leuchs, H., 178.Leutert, F., 60INDEX OF AUTHORS’ NAMES. 417Levene, P. A., 95, 96, 98, 99, 226.Levi, G. R., 297.Levin, E., 122, 123, 124.Levin, L., 236.Levine, V. E., 202.Levy, B., 200.Levy, G., 256.Levy, L. F., 151, 152.Levy, R., 58.Lewis, W. B., 15.Ley, H., 208.Lieb, H., 204.Liebhafsky, H. A., 199.Lieboff, S.L., 200.Liempt, J. A. M. van, 58, 316.Liepatov, S., 104.Limburgh, H., 337, 346.Linde, J. O., 293, 314.Lindemann, H., 397.Lhdner, J., 192, 198, 204.Ling, A. R., 102.Linhorst, E. F., 44.Link, J., 115.Linnell, W. H., 95.Linneweh, F., 162.Linneweh, W., 162.Linsert, O., 215.Linstead, R. P., 84, 108, 109, 110.Linstrom, C. F., 209.Lipman, C. B., 245.Lipman, H., 244.Liversedge, S. G., 205.Llord y Gamboa, R., 53.Lloyd, W. V., 129.Lochmann, G., 189.Locke, A., 77.Locquin, R., 90, 201.Loeb, J., 347.Loffler, H., 252.Loew, O., 245.Lowe, F., 183.Lowenstein, H., 195.Lowenthal, H., 338.Logan, M. A., 195.Lombard, M., 126.London, F., 34.Longinescu, G. G., 190, 199.Lonsdale, (Mrs.) K., 306, 384.Loo, T.L., 241.Loon, J. van, 80.Loring, F. H., 243.Loring, H. S., 92.Lortie, L., 53.Lottermoser, A., 347.Lovern, J. A., 224.Low, J. A., 129.Low, L. A., 114.Lowry, H. H., 243.Lowry, T. M., 57, 128, 129, 279, 298,Lucas, R., 192.Ludlam, E. B., 47.Lubbert, W., 159.401.REP.-VOL. XXVIII.Lucker, O., 205.Luttringhaus, A., 145, 146, 215, 216.Lukas, J., 195.Lukirsky, P., 320.Lunde, G., 315.Lundell, G. E. F., 196.Lundin, H., 192.Luton, E., 108.Lutz, R. P., 357.Lux, H., 194.Luyckz, A., 210.Lycan, W. H., 78.Macarovici, C. G., 58.McBain, J. W., 186, 233, 338, 340,Macbeth, A. K., 137.McCance, R. A., 196.McCann, D. C., 222.McCarty, E. C., 252.McClean, F. T., 256.McClendon, J. F., 199.McCollum, E. V., 256.McCombie, H., 119.McCombs, T.H., 111.McCool, M. M., 248,250.McCrea, G. W., 320.McCrumb, F. R., 186.McCubbin, R. J., 87.McDonald, E., 100.MacDonald, J., 84.McElvain, S. M., 83.McHargue, J. S., 247, 259.Machatschki, F., 300, 315, 318.Machtou, R., 207.MacInnes, D. A., 210.McIntosh, D., 133.Mack, E., jun., 43, 320.McKay, R. W., 313.McKendrick, A. G., 351.Mackinney, G., 245.McLaughlin, R. R., 98.McLennan, J. C., 313.McMichael, P., 209.McTaggart, H. A., 340.Maddocks, W. R., 65.Madelung, W., 157.Majer, W., 204.Majdel, J., 192, 196.Major, R. T., 90.Majrich, A., 200.Makarov, S. Z., 63.Makelt, 341.Maliarov, K. L., 196.Malinovski, V. S., 50.Malkin, T., 305, 320.Malowan, S. L., 202.Manchot, W., 198.Manegold.E., 350, 351.343, 348.Manny F. G., -132..M a n , J. T. W., 108.Manske, R. H. F., 91, 107, 110, 161.418 INDEX OF AUTHORS' NAMES.Mapara, H. M., 317.March, A., 349.Marder, M., 269.Marenzi, A., 203.Maricq, L., 210.Marjanovi6, V., 196.Mark, H., 103, 305, 323, 324, 325,326, 328, 329, 373, 374, 384, 395.Markovnikov, 112.Marks, S., 207.Marrian, G. F., 236, 237.Marshall, F. C. B., 74.Martin, A. R., 155.Martin, E., 64.Martin, J. H., 248.Martin, S. H., 249.Martin, W. McK., 343, 344.Martini, A., 189.Martini, H., 53.Maruyama, S., 208.Marvel, C. S., 234.Marwick, T. C., 305, 320, 321, 328,Mason, C. W., 63.Massey, H. S. W., 14.Massey, N. B., 28.Masson, (Sir) D. O., 29.Masson, I., 134.Mastin, H., 341, 345, 346.Matano, C., 313.Mathews, J.H., 341, 342, 344.Mathieu, (Mme.), 103, 316.Mathieu, M., 296.Mathur, K. G., 348.Mathur, K. N., 348.Mathur, R. P. P., 65.Matosse, F., 284, 285, 368, 370, 403.Matovinovid, V., 194.Matsui, M., 208.Matsunaga, Y., 314.Matthes, H., 78.Mattson, S., 339, 349, 353, 355, 362,Mauguin, C., 263.Maurer, K., 98.Mayer, 3'. K., 318.Mayer, G., 313.Mayrand, J. P., 194.Mazee, W. M., 27, 50.Mazur, J., 28.Meadow, J. R., 204.Mebane, W. M., 195.Mecke, R., 375, 403.Medvedeva, A., 120.Meggers, W. F., 59.Mehl, E., 304, 317, 319.Mehmel, M., 297.Mehta, T. N., 73, 74.Meidinger, W., 59.Meier, F. W., 193, 200.Meier-Mohar, T., 133.Meints, R. E., 53.Meisel, K., 317.331.363, 364.Meisenheher, J., 115.Meister, R., 85.Mellon, M.G., 186.Meloche, V. W., 199.Melville, H. W., 47.Menke, H., 373.Menon, B. K., 155, 156.Menon, K. N., 178.Menschikov, G., 165.Menzel, H., 317.Menzel, W., 55, 59.Menzer, G., 316, 318.Menzies, A. W. C., 27, 34.Menzies, R. C., 131, 133.Merwin, H. E., 63, 317.Metz, 259.Metz, C. F., 64.Meulen, J. H. van der, 195, 199.Meuwsen, A., 56.Mevius, W., 241, 242.Meyer, A., 127.Meyer, B. 5., 240, 247.Meyer, F., 56.Meyer, G. M., 95.Mever. H.. 126.M&er; J.,'53, 57.Meyer, K. H., 103, 323, 325, 326, 328,329. 384.Meyer, L., 388, 390, 391.Michael, A., 71, 81, 112.Michaolis, L., 191, 336, 354.Michalis, G., 92.Middleton, G., 192.Miers, (Sir) H., 272, 275, 277.Mignonac, G., 94.Mika, J., 191.Milas, N.A., 86.Miles, F. D., 296, 316.Milligan, W. O., 69.Mills, W. H., 394.Minetti, H., 94.Misciattelli, P., 62.Mitchell, J. A., 94.Mitra, S. K., 90.Mittasch, H., 161.Modell, u. I., 318.Moldner, H., 60.Moller, H., 51, 314, 315, 319, 320,395.Moeller, K., 59, 313.Moelwyn-Hughes, E. A, 43.Moers, K., 54, 59, 63, 313.Moesveld, A. L. T., 315.Moffitt, W. G., 118.Mohammad, S., 56.Mob, C. B. O., 14.Moldavski, B. L., 194.Moles, E., 69.Molkentin, I. R., 50.Molliard, 260.Molloy, J. J., 209.Monkman, R. J., 313.Monsarrat-Thomas, P., 153INDEX OF AUTHORS’ NAMES. 419Montequi, R., 189.Mooney, M., 340, 350.Mooney, R. C. L., 316.Moore, E. E., 211.Moore, R. B., 49.Moore, T., 222.Moore, T. S., 136.Mooy, H.H., 298, 319.Morani, V., 191.Morey, G. W., 64, 319.Mod, R., 220, 221.Morgan, G. T., 49, 52, 61, 126, 132,157, 173, 201, 398.Morgan, M. F., 353.Morgan, W. T. J., 98.Morrell, R. S., 207.Morris, V. H., 247.Morris-Jones, W., 315.Morse, C. W., 56.Morse, P. M., 20.Morton, C., 185.Morton, R. A., 146, 223, 224.Moser, G. H., 149.Moser, L., 191, 198.Mosettig, E., 173.Moskowitz, S., 63.MOM, J. A., 193.Mothes, K., 251.Mottern, H. H., 203, 255.Mougnaud, P., 199.Mousseron, M., 196.Miihlbauer, F., 132.Miiller, A., 90, 95, 272, 391, 304, 384.Miiller, C., 58, 75.Miiller, E., 210.Miiller, H., 349, 381.Miiller, K. W., 356, 359.Miiller, R. H., 201, 208.Miiller, U., 159.Mueller, W. H., 86.Miiller, W. J., 58.Mukherjec, J.N., 336, 337, 342, 345,Mulay, A. S., 251.Mumford, S. A., 75.Munch, J. C., 202.Murakami, S., 151.Murke, H., 145.Murphy, A. J., 314.Murphy, E. J., 181.Murray-Rust, D. M., 29.Musgrave, F. F., 43.Musiat, L., 163.Muskat, I. E., 74.Mussgnug, F., 316, 318, 319.Mutzenbecher, P. von, 232.Mylius, W., 197.MyrbBck, K., 225.346, 347, 348, 349.Nadenheim, F., 91.Nii eli, C., 324.Naftel, J. A., 241.Nagasako, N., 42.Nagelschmidt, J. G., 317.Nagy, Z. S., 99.Nakamura, M., 147.Nametkin, S. S., 86.Nanji, H. R., 111.Narain, R., 206.Narang, K. S., 162.Narayana, N., 258.Njray-Szab6, S. von, 102,297,318.Nasini, A. G., 208, 315, 319.Natta, G,, 295, 315, 319, 320.Naujoks, E., 158.Navarro, I., 316.Nehring, K., 196.Nejedlf, V., 209.Nelles, M., 45.Nelson, E.K., 255.Nenitzescu, C. D., 158.Nespital, W., 392.Nestle, K. T., 398.Neuburger, M., 292.Neuburger, M. C., 313, 315.Neuhaus, A., 277.Neuhaus, L., 139.Neukirck, E., 192.New, R. C. A,, 392.Newton, D. A., 340, 348, 350.Ney, (Mlle.) M. J., 285.Nial, O., 65, 315.Nicholls, F. H., 58.Nicholls, M. S., 200.Nichols, J. B., 231.Nichols, M. L., 56, 208.Nicklm, A., 53.Nicloux, M., 198, 205.Niederl, J. B., 204, 205, 208.Niederlander, K., 144.Niemann, C., 254.Nienburg, H., 159.Nierenstein, M., 148, 260.Niethammer, A., 255.Nieuwenberg, C. J. van, 188.Nieuwland, J. A., 184.Nievergelt, O., 153.Niggli, P., 289.Nikitina, E. A., 64, 201.Nikolaev, V. J., 133.Nishigori, S., 64, 314.Nitschmann, H., 317.Nitta, I., 395.Njegovan, V., 196.Noble, B.A., 319.Noda, T., 208.Noddack, I., 60.Noddack, W., 60.Nogareda, C., 52, 208.Noll, W., 196.Normann, w., 77.Norrish, R. W. G., 46.Northrop, J. H., 226, 339.Northrup, H. E., 74.Nuka, P., 195420 INDEX OF AUTHORS’ NAMES.Oakeshott, S. H., 160.Oakley, H. B., 354, 361.Oberwegner, M. E., 157.Obinata, I., 314.Obst, F., 98.Occleshaw, V. J., 63.Oesterlin, M., 118.Oftedal, I., 297, 315.Ogg, A., 316.Ohlmeyer, P., 102.Ohman, E., 293.OkB6, A,, 189.Okey, R., 206.Olcott, H. S., 222.O’Leary, W. J., 183.OlejniEek, H., 120.Olsen, J. C., 198.Ongaro, D., 257.Onorato, E., 317.Orechov, A., 165.Orlov, I. E., 199.Orlov, N. A., 156.Orlova, L., 345.Ornstein, L.S., 281.Osawa, A., 314.Osborne, (Mlle.) D., 285.Oseen, C. W., 283.Oshima, K., 293.Osterhout, W. J. V., 239, 250.Ostwdd, W., 283.Ott, E., 315, 316, 384.Ouelett, C., 197.Overhoff, J., 221, 223.Owen, O., 244.Owen, W. M., 72.Oxford, A. E., 67.Oye, M., 64, 314.osugi, s., 353.Paal, C., 70.Packer, J., 111.Pacsu, C., 99.Pagel, H. A., 201.Pa%, M., 52, 63, 316.Paine, H. H., 338.Pal, N. N., 371.Palacios, J., 315, 316.Palkin, A. P., 65.Pallmann, H., 363.Palmateer, R. E., 62.Paneth, F., 199.Pantschenko, G. A., 196.Papish, J., 49, 183.Park, B., 193.Parker, A. E., 403.Parker, F. W., 240, 243, 244.Parker, T. W., 58.Parkin, M., 138.Pm, S. W., 208.Pmavano, N., 63, 315.Parsons, A. L., 318, 319.Parsons, L.G. B., 108.Partington, J. R., 60.Partridge, H. M., 189.Patwoe, T. A., 248.Passerhi, K., 317.Passerhi, L., 53, 55, 295, 315, 317,Pastorello, S., 63, 314.Patnode, W. I., 65.Patterson, A. L., 306.Patterson, J., 266.Patterson, W. H., 202.Pauli, W., 336, 338.Pauling, L., 14, 286, 287, 290, 296,298, 300, 302, 315, 316, 317, 318,319, 367, 383, 397.Paulssen von Beck, A., 58.Pavelka, F., 190.Pavlinova, A. V., 190.Pavolini, T., 204.Pawlowski, C., 320.Payne, J. H., 86.Payne, R. J. M., 313.Peaker, C. R., 348.Pearson, T. G., 50.Pease, R. N., 50.Pehani, E., 102, 252.Pelzer, H., 331.Pember, F. A., 266.Penny, W. G., 14.Pennycuick, S. W., 337, 346, 349.Percival, E. G. V., 101, 102.Perez-Vitoria, A., 59.Perkin, W.H., 112, 178.Perreau, G., 346.Perrin, J., 341.Persson, E., 314.Pertusi, C., 190.Peace, B., 61, 317.Peters, A. T., 84, 122, 124.Peters, o., 102.Peters, R. A., 31, 206.Petsch, W., 98.Pettet, A. E. J., 201.Pettinger, N. A., 250.Pfeiffer, G. F., 84.Pfeiffer, P., 129, 134, 138.Philip, W. G., 133.Phillips, J. W. C., 75.Phillips, M., 201, 254.Phillips, T. G., 251.Philpot, J. H. L., 213,214, 215.Phragmen, G., 314.Pickett, L. W., 320.Pickett, 0. A., 340.Picon, 53.Pictet, A., 166.Pieper, B., 220.Pierce, J. S., 189.Pierre, W. H., 240, 244.Pierson, H. L., 341.Pieters, H. A. J., 198.Pietsch, E., 61, 63, 205.Pincussen, L., 207.320INDEX OF AUTHORS’ NAMES. 421Piper, C. S., 247.Piper, S. H., 305, 320.Pirani, M., 265, 266.Pirschle, K., 241.Pirtea, T.I., 190, 199.Pitts, C. R., 341.Pitzler, H., 63.Plant, (Miss) M. M. T., 95.Plant, S. G. P., 130, 160.Plato, W., 56.Platonova, M. N., 50.Ploos van Amstel, J. J. A., 273.Plyler, E. K., 403.PoboFil, F., 63.Poethke, W., 210.Pohland, E., 384.Polanyi, M., 21, 34, 47, 322.PoIicard, A. A., 201.Polinkovski, A. I., 208.Pollak, J., 122.Pollatschek, H., 268, 269.Pollauf, G., 203.Poller, K., 162.Ponder, E., 351.Ponndorf, W., 191.Pontillon, C., 260.Poole, H. J., 327.Pope, (Sir) W. J., 320.Popesco, (Mme.), 207.Popesco, A., 200.Portillo, R., 51.Posdniakova, S., 200.Posnjak, E., 64, 291, 300, 317, 318,Posternack, T., 151.Potter, G. F., 251.Powell, A. R., 197.Powell, H. M., 54.Powell, S.G., 201.Powis, F., 337, 349.Prajzler, J., 209.Pranschke, A., 91.Prasad, M., 61, 317, 320.Pr&bk, J., 53.Preece, A., 65.Preece, I. A., 253.Prelog, V., 90.Preston, G. D., 65, 313, 314.PrBvost, C., 115.Prianishnikov, D., 241.Prideaux, E. B. R., 206, 336, 343.Priestman, J., 205.Pringsheim, H., 100, 102.ProEke, O., 194, 199.Proskurnin, M., 345.Pryde, J., 95.Prytz, M., 210.Pnibram, K., 274.Pugh, E. M., 338.Pugh, W., 55.Pummerer, R., 85, 88, 221.Puri, A. N., 359.Pushin, N. A., 65.319.Puttick, A., 39.Pyman, F. L., 162, 166, 169.Quastel, J. H., 202, 227, 228.Quenstiidt, J., 315.Rabat6, J., 254.Rabat& S., 254.Rabinerson, A., 346.Rabinovitsch, A. J., 346.Rabinovitsch, M., 375.Rae, N., 50.Ragins, I.K., 144.Rahlfs, O., 59.Rai-Choudhuri, S. P., 337, 347, 348,Raikova-Kovatscheva, T. P., 190.Rajmann, E., 190.Rakovski, A. V., 64.Ramage, G. R., 160, 174.Raman, (Sir) C. V., 370.Ramaswamy, C., 284.Ramsden, (Miss) E., 69.Ramsperger, H. C., 48, 43, 44.Randall, J. T., 319.Randall, S. S., 234.Rankov, G., 78.Rao, A. N., 337, 347.Rao, B. S., 57.Rao, M. R. A., 57.Raper, R., 175, 176.Rasetti, F., 403.Rask, 0. S., 183, 256.Rauch, H., 144.Rauscher, K., 70.Rawling, S. O., 191.Ray, H. L., 345, 346.Ray, J. N., 162.Ray, P., 188, 194.Raymond, A. L., 98.Rebmann, L., 221.Recchia, E., 62.Redeker, H. E., 209.Redlich, O., 29.Redmond, J. C., 196.Reerink, E. H., 213.Reetz, T., 191.Rehren, (Frl.) I., 378.Reich-Rohrwig, W., 196.Reichstein, I., 150.Reid, E.E., 94.Reid, G. H., 11 1.Reif, W., 193, 198.Reifenberg, A., 346.Reihlen, H., 61, 62, 75, 398.Reilly, J., 100.Reimers, F., 206.Rein, E., 120.Reindel, F., 143, 144.Reindel, W., 221.Reinhardt, L., 306.349422 INDEX OF AUTHORS’ NAMES.Reis, A., 396.Remesov, I., 347.Remfry, F. G. P., 166.Remington, R. E., 199.Reymond, F., 57.Reynolds, R. J. W., 95.Rheinboldt, H., 128.Ribere, M., 204.Ribotti-Lissone, G., 78.Rice, F. E., 353.Richardson, 0. W., 402.Richtmyer, F. K., 266.Richtmyer, N. K., 82.Rideal, E. K., 39.Rieche, A., 85.Riedel, W., 347.Riehm, H., 190.Riemenschneider, R. W., 81.Riese, W., 205.Riesenfeld, E. H., 50.Riley, H. L., 51.Rimington, C., 333.Rinck, E., 64.Ringbom, A., 210.Rinne, E., 317.Rippel, K., 259, 260.Rising, M.M., 90.Ritt, E., 126.Ritter, R. C., 337.Ritter, W., 91.Ritzau, G., 64.Roberts, H. S., 63, 317.Roberts, J. K., 35.Roberts, 0. L., 314.Robertson, A., 97, 147, 151, 152, 163,154, 165, 255.Robertson, J. M., 249, 306, 320, 384.Robinson, (Mrs.) G. M., 153.Robinson, M. E., 232.Robinson, P. H., 118.Robinson, P. L., 50, 52, 58, 60.Robinson, R., 67, 80, 83, 117, 118,134, 151, 152, 153, 166, 178.Robinson, R. A., 53, 185, 191.Robison, R., 98.Rocha, H. J., 314.Roche, (Mme.) A., 210.Roche, J., 210.Rochow, E. G., 58.Rode, E. J., 64, 60.Rodebush, W. H., 392.Romer, G. H., 320.Rojahn, C. A., 207.Roldcin, J. C., 188.Roman, H. L., 54.Romburgh, G.van, 87.Romburgh, P. van, 87.Romeyn, H., 194.Rombn, J. V., 210.Rona, P., 342.Roodvoets, A. C. W., 346,349.Rooksby, H. P., 317, 319.Rosbaud, P., 315, 316.Rosenberg, W., 202.Rosenfeld, P., 29.Rosenheim, A., 56, 58.Rosenheim, O., 215.Rosenthaler, L., 202, 203, 204.Rosovskaja-Rossienskaja, R., 199.Ross, C. S., 318.Ross, J., 71, 81.Rossi, T., 202.Rossmann, E., 191.Rostkovski, A. P., 63, 316.Rothe, O., 194.Rothmund, V., 356, 357.Rothstein, E., 105, 116.Rowe, F. M., 122, 123, 124.Rowntree, R. K., 64.Roy, B. C., 345, 346.Royer, L., 279.Ruark, A. E., 395.Rubel, W. M., 200.Rudge, A. J., 60.Rueff, G., 104.Ruemele, T., 207.Ruff, O., 55, 59, 63.Rumer, G., 14.RUOSS, H., 199.Russell, A. S., 55.Russell, (Sir) E.J., 366.Rutgers, J. J., 204.Ruthardt, K., 209.Rutherford, (Lord), 14, 16.Ruzicka, L., 120.Rydbom, M., 220, 222.Sabetay, S., 205.Sabetta, V. J., 198.Sachs, G., 273, 293, 313.Sack, H., 379, 381.Saenger, H., 58.Sanger, R., 391.Siingewald, R., 394, 396.Sagortschev, B., 191.Saha, H., 193.Sakamura, T., 258.Sakurada, I., 103.Sakurai, H., 54.Salant, E. O., 403.Salditt, F., 34.Salkind, J., 120.Salter, R. M., 353.Salter, W. T., 235.Salvia, R., 315.Samec, M., 102, 252, 253.Sampson, A. W., 252.Samuel, G., 247.Samuels, H., 96.SBnchez, J. A., 202, 204.Sand, H. J. S., 209.Sandell, E. B., 200.Sanders, J. P., 66.Sandhaas, W., 91.Sandin, R. B., 204INDEX OF AUTHORS’ NAMES. 423SQndor, S., 392, 397.Sandow, D., 403.Sandqvist, H., 143.Sandrock, W.F., 155.Sanfourche, A., 210.Sapper, A., 317.Sarkar, P. B., 61, 188.Sarver, L. A., 191, 194.Sasaki, K., 313.Sasaki, Y., 205.Saschek, W. J., 204.Sastri, B. N., 249, 258.Sato, S., 149.Sauerberg, H., 91.Sauerwald, F., 62.Sayre, J. D., 247, 249.Sbiera, E. R., 50.Schaefer, C., 284, 285, 368, 370.Schairer, J. E., 63.Schall, B. M., 188, 200.Scharrer, K., 246.Schaum, K., 348.Scheffer, F. E. C., 57.Scheffers, H. W., 78.Scheflan, L., 198.Scheibe, G., 209.Scheil, E., 268.Scheinkmann, A., 188.Schenck, O., 77.Schenk, M., 104.Schenk, P. W., 55.Scherer, G. A., 50.Scherer, P. C., jun., 104.Scherillo, A., 297, 315, 317, 321.Scherrer, P., 322, 331, 373.Schiebold, E., 318.Schiebold, F., 302.Schiedewitz, H., 70.Schimmelschmidt, K., 121.Schleede, A., 395.Schleicher, A., 183.Schlesinger, H.I., 61, 62.Schmalbeck, (Frl.) O., 159.Schmandt, W., 275.Schmeller, M., 227.Schmidt, A., 198.Schmidt, E., 174, 206.Schmidt, J., 188, 204.Schmidt, K., 241.Schmidt, O., 77.Schmitz, J., 143.Schnegg, H., 206.Schneider, G. C. C. C., 86.Schneider, K., 33, 139, 306, 321.Schnorr, W., 278.Schnoutka, 197.Schober, H., 59.Schoeller, W. R., 197.Schonberger, W., 143.Schonheimer, R., 144, 206.Schapf, C., 174, 177.SchOpp, K., 221.Schoettler, O., 209.Schofield, R. K., 365, 366.Scholder, R., 56.Schollenberger, C. J., 194.Schommer, W., 139.Schonefeld, P., 317.Schoonover, I. C., 210.Schormiiller, J., 192.Schou, S.A., 207, 403.Schrauth, W., 77.Schriner, R. Z., 201.Schropp, W., 246.Schuette, H. A., 206.Schulek, E., 198.Schulek, F., 195.Schuler, L., 122.Schulman, J. H., 39.Schulz, F., 53, 205.Schulze, A., 320.Schumacher, H. J., 43, 44.Schumb, W. C., 54, 197.Schusta, F., 203.Schusterius, C. A., 316.Schutz, W., 397.Schwabe, K., 58.Schwalbach, A., 89.Schwappach, A., 205.Schwartz, A. M., 202.Schwartz, R., 55.Schwartz, W., 259.Schwejtzer, E., 183, 209.Schweitzer, O., 89, 103.Scott, D. A., 233.Scott, N. D., 337.Scott, W. E., 52.Scott, W. W., 192.Scott Blair, G. W., 365, 366.Seaman, W., 118.Secareanu, S., 208.Seguin, (Mlle.) L., 202, 208.Seifert, H., 316.Seifert, R., 207.Seka, R., 147, 201.Sekito, S., 313, 314.Selilikar, S., 102, 253.Seltz, H., 184.Semeria, G.B., 78.Senftleben, H., 378.Sen-Gupta, P. N., 371.Sergeev, A., 189.Serres, A., 317.Seshadri, T. R., 152.Seuferling, F., 51, 53.Sexton, W. A., 144, 146.Seyewetz, A., 298.Shah, C. C., 50.Shandorov, A. M., 195.Shappell, M. D., 296.Shaw, I?. R., 116.Shead, A. C., 197.Shearer, W. L., 365.Shepherd, F., 136.Shibata, K., 147, 148, 154.Shibita, B., 175424 INDEX OF AUTHORS’ NAMES.Shimizu, K., 320.Shimura, S, 294.Shinoda, J., 149.Shipp, H. L., 196.Shive, J. W., 248.Shoppee, C. W., 106, 107.Shorter, S., 327.Shubnikov, A., 275, 276.Shutts, L. W., 371.Sichelschmidt, A., 63.Sicklen, W. van, 268.Sickman, D. V., 196.Sidgwick, N. V., 128, 129, 130, 131,133, 186, 392, 397.Siebeniiuger, H., 260, 261.Sieber, W., 91.Signer, R., 54, 89.Sille, G., 195.Silverman, L., 184.Simmons, J.P., 64.Simon, A., 59, 130, 191.Simonis, M., 365.Simonsen, J. L., 80, 133.Simpson, S. G., 197.Sisley, P., 189.Sivadjian, J., 202, 205.Sjogren, B., 231, 232, 233.Sjiiman, P., 319.Skariyfiski, B., 236.Skinner, S., 77.Skita, A., 90.Skopintzev, B. A., 199.Skopp, E., 196.Slater, J. C., 286, 287, 297, 367.Slavina, D. S., 64.Sloat, C. A., 34.Slonim, C., 52.Slooff, G., 86.Slottman, G. V., 349.Smart, B. W., 90.Smeets, C., 65.Smirnow, A. I., 244.Smit, W. C., 86.Smith, A. M., 249.Smith, C. C., 138.Smith, E. L., 186.SmitL, G. Y., 191, 192, 197.Smith, H. A., 320.Smith, H. G., 34, 70, 74.Smith, J.A. B., 95.Smith, J. C., 67.Smith, J. H. C., 219.Smith, J. W., 26, 50, 200.Smith, S. P., 337.Smits, A., 27, 50.Smoluchowski, M. von, 335,339,344,Smyth, C. P., 130, 379, 388, 391.Snell, J. M., 83.Snesaro-v, A. P., 207.Snow, C. P., 403.Snow, R. D., 70.Sobrinho, A. P., 194.348.Socias, L., 211.Sohns, F., 254.Sokolov, N. A., 199.Sokolov, S. I., 63.Sokolova, N., 104.Solaja, B., 194.Solf, K., 350, 351.Solomon, D., 315.Solomonica, E., 158.Solovian, A., 50.Sommer, A. L., 244, 245.Sorokin, H., 244.Sorokin, V., 47.Southwood, W. W., 55.Spack, A., 63.Spacu, G., 58.Spiith, E., 167, 168, 169, 171, 173.Spangenberg, K., 277.Speakman, J. B., 40, 327, 332, 333,Speight, E. A., 110.Spencer, F., 116.Spielberger, F., 3 18.Spiers, F.W., 320.Spittle, H. M., 58.Sponer, H., 375.Sponsler, 0. L., 320, 322, 328.Sprenger, G., 43, 44.Spring, F. S., 144, 145.Spychalski, R., 320.Stackelberg, M. von, 296.Stahl, W., 198.Staley, W. D., 208.Stamm, A. J., 346.Stanley, W. M., 143.Stansfield, E., 204.Starker, A., 102.Stas, M. E., 195.Staub, L., 55.Stauble, G., 121.Staudinger, H., 89, 103, 126.Steacie, E. W. R., 37, 44.Stedehouder, P. L., 316.Steele, F-. A., 317.Steger, A., 78, 80.Steib, H., 90.Steiger, R. E., 90, 120.Steigerwaldt, F., 225.Stein, G., 87, 146.Steiner, B., 56, 64.Steiner, M., 252.Steiner, O., 192.Steinfeld, H., 60, 188.Steinhart, H., 259.Steinwehr, H. von, 320.Stelling, O., 210.Stenbeck, S., 315.Stepanov, F.N., 160.Stephen, H., 54.Stern, F., 90.Stern, O., 350.Stern, T. E., 290.Stevenson, J. W., 100.334INDEX OF AUTHORS’ NAMES. 426Stickdorn, K., 77.Stillwell, C. W., 314.Stock, 341.Stock, A., 53, 194.Stockdale, D., 313.Stoddart, E. M., 60.Stober, F., 269, 271, 272.StojkoviC., J.,. 102.Stoklasa, 245.Stone, I., 188, 189.Stone, S., 185, 191.Storer, N. M., 204.Stranski, I. N., 275, 276.Strasser, E., 192.Stratton, G., 135.Straumanis, M., 265, 266.Street, A., 41, 326, 327.Streight, H. R. L., 95.Strickler, A., 341, 342, 344.Stubblefield, A., 208.Stumper, R., 26.Sturdivant, J. H., 300.hmsa, F., 120.Suchier, A., 208.Suchfr, K., 209.Suckfiill, F., 145.Sudborough, J. J., 134, 138.Sugden, S., 129, 131, 399.Sullivan, J.T., 251.Sullivan, M. X., 207.Sumner, C. G., 339, 340, 350.Sumner, J. B., 225, 226.Susemihl, W., 92.Susich, G. von, 327.Sutherland, J. W., 204.Sutter, E., 265.Sutton, L. E., 19, 131, 133, 388, 392,393, 396, 397.Suzuki, B., 78, 79.Svedberg, T., 230, 231, 232, 233, 333,335, 336, 337, 338, 339.Swart, E. L., 27, 50.Swartz, C. A., 338.Szab6, Z., 199.Szancer, H., 202.Szebelledy, L., 194, 195, 200.Tafel, V., 195.Taimni, I. K., 53.Takeda, S., 65.Talen, H. W., 120.Tama, C., 122.Tamaki, H., 149.Tamaru, K., 314.Tamaru, S., 54.Tamchyna, J. V., 190.Tamchyna, V. V., 188.Tammann, G., 270, 273, 314.Tanaka, S., 313.Tanaka, Y., 54, 320.Tanamev, I., 192.Tananaev, N. A., 189.Taryh, E., 58.Tauber, H., 226.Tausz, J., 209.Taylor, H.A., 64.Taylor, H. M., 25.Taylor, H. S., 36, 38, 403.Tayloi, N. W., 317.Taylor, T. W. J., 396.Taylor, W. H., 318.Tchakirian, A., 55.Teakle, L. J. H., 243.Teece, (Miss) E. G., 96.Teiss, R. V., 199.Teitelbaum, M., 194, 201.Tendeloo, H. J. C., 337, 348.Tendulkar, M. G., 61.Tennkwood, C. R. S., 175Tepper, W., 122.Terpstra, P., 316.Terrey, H., 209.Terrill, J. N., 206.Thzak, B., 201.Thakur, R. S., 109.Thayer, S. A., 236.Theilacker, W., 317.Theodorovitsch, V. P., 50.Thewlis, J., 299.Thibaut, J., 305.Thiele, H., 320, 397.Thiessen, P. A., 60, 317, 340.Thilu, E., 61.Thomas, H. A., 95, 105.Thomas, J. S., 55.Thompson, A., 97, 224.Thompson, H. W., 47.Thomson, G. P., 374.Thomson, J.J., 388.Thon, N., 351.Thorpe, J. F., 74, 111, 112.Thorvaldson, T., 317.Thouet, H., 143.Thurnwald, H., 197, 200.Tichomirov, V. I., 50.Tichomirova, A. M., 135.Tidmore, J. W., 243.Timpe, O., 162.Tipson, R. S., 95, 9G, 99, 101.Tischtschenko, W. W., 156.Tiselius, A., 337.Tiukov, D., 261.Todd, A. R., 142.Todd, C., 337.Tolksdorf, S., 316.Tolman, R. C., 44.TomiEek, O., 199.Tomita, M., 90, 170.Tomula, E. S., 195.Toone, G. C., 202.Topley, B., 34.Torres, C., 211.Torrey, G. G., 52.Toth, G., 105.Tougarinoff, B., 188.0 426 INDEX OF AUTHORS’ NAMES.Tourtelotte, D., 183.Trautz, 0. R., 204, 205, 318.Travers, A., 197, 210.Tremain, H. E., 190.Trenner, N. R., 64.Triebel, H., 201.Trillat, J. J., 272, 304.Tromel, G., 318.Troensegaard, N., 330.Trogus, C., 103, 104, 328, 329.Truesdale, E.C., 59.Tschepelevetzky, M., 200.Tschirch, E., 202.Tschitschibabin, A. E., 160.Tseng, C. L., 201.Tsugi, T., 56.Tsururni, S., 205.Tunell, G., 64, 318.Tuorila, P., 338, 339, 345, 346, 349,Turner, M. E., 206.Tuthill, E., 196.Twyman, F., 182, 183, 209.Tyndall, E. P. T., 268, 270.360, 364.Ulich, H., 392.Underwood, H. W., jun., 202.Unger, W., 46.Ungerer, E., 359.Urbach, C., 208.Urey, H. C., 395, 403.Urry, W. D., 199.Vageler, P. W. E., 357.Valentin, F., 97.Valiaschko, V. A., 194.Vallance, R. H., 58.Van Horn, K. K., 314.Van Rysselberge, P. J., 196.Van Valkenburgh, H. B., 61.Varga, G., 338.Varley, H., 342.Vastagh, G., 198.Vaughn, T.H., 184.Vedenski, A. V., 56.Veeder, J. M., 58.Veen, H. van der, 80.Vegard, L., 303, 319.Velculesco, A. J., 210.Velluz, L., 196.Venkataraman, K., 154, 155, 156.Venkateswaran, S., 370, 403.Verdino, A., 204.Verhulst, J., 93.Vernon, &I. A., 279.Verweel, H. J., 296.Veself, V., 120.Veszi, G., 35.Vetter, H., 60.Vickery, H. B., 92.Vicovsky, V., 194.‘iditz, F., 133.‘idyarthi, N. L., 78, 79.‘iebock, F., 205.rigfusson, V. A., 63, 317, 319.Tignon, P., 191.Tincent, V., 246.rirup, P. K., 104.Ws, F., 337.rocke, F., 139.Togel, R., 64.Toigt, A., 187.Tojatsakis, M. E., 53.Tolk, H., 142.Jolmer, M., 42,265, 266,269, 271, 275.Jolz, J. L., 85.Jorlander, D., 280.JotoEek, E., 97.Naddington, G., 42.Nagenmann, K., 201.Wagner, C.L., 243.Wagner, E. C., 193, 205.Wagner, H., 317.Wagner, 0. H., 51.Wagner-Jauregg, T., 71, 87.Wahl, A., 122.Wahl, W., 131.Wainer, E., 49.Wakernan, R. L., 182.Waksberg, N. M., 62, 63.Walrsman, S. A., 253.Waldeck, W. F., 64.Waldschmidt-Leitz, E., 225.Walker, T. K., 261.Wallace, J. H., jun., 192.Walleuer, H., 55.Walls, H. N., 156.Walls, L. P., 173.Walter, E., 144.Walter, H., 248.Walz, E., 150, 255.Ward, A. F. H., 38.Ward, A. M., 189, 195.Ward, D., 116.Ward, F. A. B., 14.Ward, T. J., 194.Wardlaw, W., 68, 399.Ware, (Miss) G. M., 205.Warnat, K., 178.Warren, B. E., 302, 318.Warren, F. L., 28.Wartenberg, H. von, 63, 377, 403.Watanabe, T., 316.Waters, R. B., 97.Watkin, J.E., 252.Watson, E. M., 111.Watson, W. W., 403.Wattiez, N., 254.Webb, C. E., 65.Webb, H. W., 66.Webb, J. I., 96.Weber, A,, 265, 275AUTHORS’ NAMES. ..-...-- b INUEA UJ! 427Webster, T. A., 213, 214, 216.Weeds, J., 313.Wehrli, H., 220.Weibke, F., 60, 187.Weichmann, A., 143.Weichselbaum, T. E., 234.Weidenfeld, L., 192.Weidinger, A., 102.Weidlich, G., 219.Weinbaum, O., 313.Weinberg, A. von, 386.Weinzierl, J., 192.Weiser, H. B., 59.Weiss, F., 207.Weiss, J., 60.Weissberger, A., 394, 396, 398.Weisselberg, K., 202.Weissenberg, K., 328, 398.Weisskopf, V., 23.Weitz, E., 139.Weizmann, M., 206.Welch, K. N., 83.Weldon, M. D., 250.Wenger, P., 192.Wentworth, S. W., 251.Werkman, C. H., 208.Werner, A,, 134.Werner, H., 206.Wertenburg, L., 120.Wessbecher, H., 122.Wessely, F., 149.West, J., 297, 300, 302.West, R., 236.West, W., 403.West, W.A., 27.Westfall, B. B., 195.Westgren, A., 66, 294, 314, 315.Wettstein, A., 176.Wever, F., 62, 314.Weyer, I., 319.Whang, S. H., 347.Wheatley, A. H. M., 227.Wheeler, A. S., 122.Wherry, E. T., 318.Whitby, G. S., 88.Whitby, L., 62.White, T. A., 36, 39.White, T. N., 306.Whitman, B., 206.Whitworth, J. B., 320.Wibaut, J. P., 66, 120.Wiberg, E., 63.Widdowson. E. M.. 206.Widmer, R.; 163.Wiegner, G., 363, 366, 369, 360.Wieland, H., 139, 141, 142, 143, 161,Wiener, A., 102.Wiercihski, J., 210.Wierl, R., 14, 374.Wiertelak, J., 346.Wijk, A. van, 213.Wijkman, N., 261.166.Wilcox, L. V., 198.Wiley, R. C., 193, 196.Wilkinson, D. G., 119, 120.Willems, H. W. V., 63.Williams, A. S., 208.Williams, J. B., 193.Williams, J. W., 388, 394, 395.Williams, N. H., 124.Williams, R. C., 340.Williams, R. T., 95.Williamson, A. T., 38.Willigen, P. C. van der, 336, 337, 342,345, 346, 347, 349.Willis, G. H., 128, 129, 133, 134, 138,139.Willis, L. G., 241, 247.Willstaedt, H., 131.Willstlitter, R., 122.Wilson, B. D., 353.Wilson, E. B., jun., 391.Wilson, (Mrs.) M., 210.Wilson, R. E., 365.Wiltshire, J. L., 114.Winckler, H., 159.Windaus, A., 143, 144, 145, 146, 213,215, 216, 219.Windus, W., 234.Winfield, F. T., 206.Winslow, C. E. A., 342, 346.Winten, D., 169.Winterfeld, K., 174, 176.Winteratein, A., 163.Wintgen, R., 338.Witmer, E. E., 402.WohIer, L., 61.Wohl, A., 91.Wolfenden, J. H., 28,33,34,40.Wolff, H., 386.Wolff, L. K., 221, 223.Wolfke, M., 28.Wolfrom, M. L., 96, 97.Wolker, W., 196.Woltersdorf, J., 357.woo, s. c., 210.Wood, J. H., 136.Wood, L. J., 314.Wood, R. J., 192.Wood, R. W., 371, 378,403.Wood, W. A., 313, 314.Woods, H. J., 231, 326, 332.Woodward, L. A., 186.Woodworth, C. W., 258.Woolvin, c. s., 98.Wooster, N., 296, 316, 316.Wooster, W. A,, 286, 296.Wooten, L. A., 184.Work, R. W., 55.Wormwell, F., 340, 344.Wrede, E., 381.Wrettblad, P. E., 316.Wrigge, 3’. W., 61, 60, 201.Wright, C. P., 29.Wright, S. L., 27428 INDEX OF AUTHORS’ NAMES.Wulffsohn, A,, 120.Wyart, J., 319.Wyatt, W. F., 134.Wyckoff, 263, 305, 317, 320, 373.Wymore, I. J., 314.Wynne-Jones, W. F. K., 29.Wynn-Williams, C. E., 14.Yagoda, H., 189.Yakimach, A., 59.Yamamoto, K., 318.Yamamoto, T., 315.Yamazaki, K., 210.Yang, P. S., 90.Yasuda, M., 206.Yates, R. C., 370.Yen, Y., 150.Yofe, J., 205.Yost, D. M., 210.Youden, W. J., 248.Young, J., 268, 320.Young, R. C., 55.Zachariasen, W. H., 288, 296, 297,300, 302, 316, 318, 403.Zahn, C. T., 130.Zambonini, F., 319.Zamtra, J. E., 313.Zartman, I. F., 379.Zbinden, C., 209.Zechmeister, L., 105.Zeh, H. P., 345.Zeile, K., 225.Zeller, A., 203.Zemplh, G., 99.Zener, C., 14.Zervas, L., 98.Ziegler, G. E., 297, 316.Zimmerman, M., 203.Zimpelmann, E., 135.Zintl, E., 51, 295.Zinzadzd, C. R., 58.Zitko, V., 102, 253.Zocher, H., 282.Zolina, V., 283.Zombory, L. von, 191, 196.Zsigmondy, 33 1.Zuhn, E. M., 62.Zur-Miihlen, O., von, 192.Zwanzig, A., 347, 351

ISSN:0365-6217    

DOI:10.1039/AR9312800405

出版商:RSC    

年代:1931

数据来源: RSC