摘要:

ANNUAL REPORTSPROGRESS OF CHEMISTRY.ON TEANNUAL REPORTSH. B. BAKER, C.B.E., D.Sc., F.R.S.E. C. C. BALY, C.E.E., P.R.S.H. BASSETT, D.Sc., P11.D.O.L. BRAIIY, D.s~.A.W.CROSSLEY, C.M.G., C.B.E.,F.R.S.H. W. DUDLEY, O.B.E., KSc., P11.D.U. R. EVAXS, M.A.J. J. Fox, O.B.E., D.Sc.C. S. GIBSON, O.B.E., M.A.A. J. GREENAWAY, F.I.C.I. 31. HEILBRON, D.S.O., D.Sc.T. A. HENRY, D.Sc.I!. G. DONNAN, C.B.E., M.A., F.R.S.ON THEC. I(. INGOLD, D.Sc., F.R.S.H. MCCOMB~E, D.S.O., M.C., D.Sc.J. I. 0. MAYBON, M.B.E., D.Sc.W. 13. MILLS, Sc.D., F.R.S.T. S. MOORE, M.A., R.Sc.J. R. PARTINGTON, M.B.E., D.Sc.J. C. PHILIP, O.B.E., D.Sc., F.R.S.R. H. PICICARD, D.Sc., F.R.S.T. S. PRICE, O.B.E., D.Sc., F.R.S.F. L. PYMAN, D.Sc., F.R.S.J. F. THORPE, C.B.E., D.Sc., F.R.S.W.P. WYNNE, D.Sc., F.R.S.G. T. bfORGAN, O.B.E., D.Sc., F.R.S.PROGRESS OF CHEMISTRYW. T. ASTBURY.Sir. W. H. RRAGG, K.B.E., F.R.S.II. V. A. BRISCOE, D.Sc.W. CLAYTON, D.Sc.J. E. COATES, O.E.E., D.Sc.C. Donfa:, M.A., D.Sc.F O B 1925.73. A. ELLIS, M.A.J. J.Fox, O.B.E., D.Sc.T. A. HEN’RY, D.Sc.C. K. INGOLD, D.Sc., F.R.S.H. J. PAGE, M.B.E., B.Sc.L. J. SPENCER, M.A., Sc.D., F.R.S.ISSUED BY THE CHEMICAL SOCIETY.V O l . XXII.LONDON :GURNEY dz; J A C K S O N , 33 PATEREOSTER ROW, E.C.4.1926PRINTED IN GREAT BRITAIN BYRICHARD CLAY & SONS, LIMITED,BUNGAY, SUFFOLICONTZNTS.PAGEGENERAL AND PHYSTCAT, CAFMTSTRY. Py J. I?. COATES, O.B.E.,D.Sc. . . . . . . . . . . . 11INORGANIC CHEMISTRY. By 11. V. A. BRISCOE, D.Sc. .. . 42ORGANIC CHEMISTRY :-Part ~.-ALIPHATIC DIVISION. By CHARLES DOR$E, M.A., D.Sc. . . 67Part II.-HOMOCYCLIC DIVISION. By C. K. INGOLD, D.Sc., F.R.S. . 105Part III.-HETEROCYCLIC DIVISION. By T. A. HENRY, D.Sc. . . 132ANALYTICAL CHEMISTRY'. By J. J. Fox, O.B.E., D.Sc., and B. A.ELLIS, M.A. . . . . . . . . . . 168BIOCHEMISTRY. By J. C. DRUMNOND, D.Sc., md H. J. PAGE, M.B.E.,B.Sc. . . . . . . . . . . . 194CRYSTALLOGRAPHY. By 11'. T. ASTDURP and Sir U'. H. BRAGG, K.B.E.,F.R.S. . . . . . . . . . . . 240MINERALOGICAL CHEMISTRY. By L. J. SPENCER, M.A., Sc.D., F.R.S. 259COLLOID CHEMISTRY. By WILLIAM CLAYTON, D.Sc. . . . 281PHOTOCHEMISTRY, 1914-1925. By A. J. ALLMAND, M.C., D.Sc. . . 33TABLE OD’ ABBREVIATIONS EMPLOYED I N THEREFERENCES.ABBREVIATED TITLE,A .. . . . .Amer. Chem. J. . . .Amer. J. Anat. . . .Amer. J. Phamn. . .Amer. J. PhysioZ. . .Amer. J. Xci. . . .Amer. Nin. . . .Aml. Asoc. Qtcim. ArycntinnAnal. Fis. &uim . .Analyst . . . .Annalen . . . .Ann. AppZ. Bid. . .Ann. Bot. . . . .Ann. Chim. . . .A m , Chim. anal. . .Ann. Chim. Appl. . .Ann. Chim. Phys. . .Ann. Facultd Sci. UarseilleAnn. Physik . . .Ann. Phys. Chem. . .Ann. Physique . . .Ann. Report .Ann. Soc. Gdd. Eelye(Bul1.jAnn. Soc. Gt?oZ. Belge (Publ.Congo Bclge) . . .Arch. d i Patalog. e din.Medica . . . .Arch. exp. Path. Pharm. .Arch. Gynak . . .Arch. Pharm. . . .Arch. Verdazcungskr. . .Arkiv Kem. illin. Geol. .Atti R. Accad. Lineei . .Australian J.Exp. Biol.Med. Sci. . . .Beitr. Chem. Physiol. Pat7~Beitr. Kryst. Alin. . .Ber. . . . . .Ber. Deut. physikal. Ges. .The1JOURNAL.Abstracts in Journal of the Chemical Society, orAmerican Chemical Journal.American Journal of Anatomy.American Journal of Pharmacy.American Journal of Physiology.American Journal of Science.American Mineralogist.Anales de la Asociaci6n Quimica Argentina.Anales de la Sociednd Espan6la Fisica y Quimica.The Analyst.Justas Liebig’s Annalen der Chemie.Annals of Applied Biology.Annals of Botany.Annales de Chimie.Annales de Ohimie analgti ue appliqu6e A 1’IndustriesAnnali di Chimica Applicats.Annales de Chiniie et de Physique.Annales de la Facult6 des Sciences de Marseille.Aiinalen der Physik.Annalen der Physik und Chemie.Annales de Physique.Annual Reports of the Chemical Society.Annales de la Soci6tB g6ologique de Belgiqne :(Bulletin).Aiiales de la SociBt6 ghologique de Belgique : (Publi-cations relatives au Congo Belge).Archivio di Patalogia e clinica Medica.Archiv fur experimentelle Patliologie und Pharma-Archiv fur Gynakologie.Archiv der Pharmazie.Archiv fur Verdauungskrankheiten.Arkiv for Kemi, Mineralogi och Geologi.Atti (Kendiconti, Memorie) della Renle AccademiaNazionale dei Lincei, classe di scienze fisichc,niatematiche e natnrali, Roma.Australian Journal of Esperiniental Biology andMedical Science.Reitrage z tir chemisclien Physiologic und Pathologie.Beitrage zur Krystallograpliie nnd Mineralogie.Berichte der Deutschen Chemischen Gesellschaft.Berichte der Deutschen physikalischen Gesellschaft.issued by the Bureau of Chemical Abstracts.*A l’A,aiiculture, h la darmacie et B la Hiologie.kologie.rear is not inserted in references t o 1925TABLE OF ABBREVIATIONS EMPLOYED IN THE REFERENCES.viiABBREVKATED TI*rm.Biochem. J. . . .Biochem. 2. . , .13011. C’him. farm. . .BreniLstof Chem. . .Urit. Assoc. R5ports . .BwZ. Soc. Chim. Romdnia .Bull. Acad. Sci. Cracow .B d l . Acad. Sci. ICitssie .Bull. Soc. chim,. . .Bull. Soc. chim. Belg. .Bull. SOC. Chim. bid. ,Bull. SOC. franc. Min. .Bull. U.S. Geol. Szcn*ey .Celbulosechem. . .Centr. Nin. . . .Chenz. Listy . , .Chcm. ATCUs . . .Chem. Umschau . . .Chem. Feekblnd , .C‘hem.Ztg. . . .Chem. Zentr. . . .Chim. et h c l . . . .Gompt. rend. . + .C. B. Acad. Sci. RiLssie .Conapt. rend. l’rav. Lab.Carlsberg. . . .Danske Vid. Selsk. McitJt. -fi. Medd. . . .Deutsch. Zed. Wock. . .Gazzetta . . . .Geol. For. Porh. . . .Giorn. Chim. Ind. Appl. .Ilelv. Chim. Acta . .Indian Forest Aec. . .Ind. Eng. Chem. . . .Inst. Ph ys. Chem. IZcs. TokyoJ. . . . .Jahrb: Min. 6eil.-Bd. .J. Agric. Res. . . .J. Agric. Sci. . . .J. Amer. Ceram. Soe. . .J. Amer. Chem. SOC. . ,J. Amer. Ned. Assoc. . .J. Amer. Phnrm. Assoc. .J. Amer. Soc. Agron. , .J. Assoc. Off. Agric. Chem.J. Biol. Chem. . . .J. Chem. Ind. Japan . .J. Chim. pltys. . . .J. Exper. Med. . . .J. F a . Eng. Tokyo . .JOURNAL.The Biochemical Journal.Biochemische Zeitsrhrift.Holletino Chimico farmaceutico.Brennstoff Chemie.British Association Reports for the Advancement ofRulBtinul Societiitei de Chimie din Romania.Bulletin international de 1’Acadkmie des Sciences deBulletin de 1’Acadkmie des Sciences de Russie.Bulletin de la Sociktk chimique de France.Bulletin de la Soci6td chimique de Belgique.Bulletin de la Socidtd de Chimie biologique.Bulletin de la Soci6tk franpaisa de Minhalogie.Bulletin of the U.S.Geological Survey.Cellulosechernie.Centralblatt fur Mineralogie, Geologie nnd Palaonto-logie.Chemickk V t y pro Vfdu a Prdmysl. Organ de la.“ Ceslta chemicka Spolednost pro Vedu a,Prfiniysl.”Chemical News.Cheniische Umschau auf dem Gehieto der Fette, Ode,Wachse, und Harze.Chemisch Weelrblad.Chemiker Zeitung.Chemisches Zentralblatt.Chimie et lndnstrie.Comptes rendus hebdomadaires des SQances deComptes rendus de 1’Acaddmie des Sciences de Russie.Conintes rendus des Travaux du Laboratoire Carls-Science.Cracovie.l’tlcaddmie des Sciences.berg.Meddelelser.Danske Videnskabernes Selskab, Mathematisk-fisiskeDeutsche medizinische Wochenschrift .Gazzetta chimica italiana.Geologiska Foreningens i Stockholm Forhandlingar.Giornale di Chimica Industriale ed Applicata.Helvetica Chimica Acta.Indian Forest Records.Industrial and Engineering Chemistry.Institute of Physical and Chemical Research, Tokyo.Journal of the Chemical Society.Neues Jalvbuch fur Mineralogie, Geologie und Pal&ontologie, Beilage- Band.Journal of Agricultural Research.Journal of Agricultural Science.Journal of the American Ceramic Society.J onrnal of the American Chemical Society.Journal of the American Medical Association.Journal of the American Pharmaceutical Association.Journal of the American Society of Agronomy.Journal of the Association of Official AgriculturalJournal of Biological Chemistry.Journal of Chemical Industry, Japan.Journal de Chimie physique.Journal of Experimental Medicine.Journal of the Faculty of Engineering, Tokyo Im-Chemists.perial Universityviii TABLE OF ABBREVIATIONS EMPLOYED IN THE REFERENCES.ABBREVIATED TITLE.J.Franklin Imt. . .J. Gen. Physiol. . . .J. Geol. . . . .J. Geol. SOC. Tokyo . .J. Indian Chem.Soc. . .J. Indian Inst. Sci. . .J. Indust. Hyqicne . .J. Inst. Brewing . .J. Inst. Metals . . .J. Zon Steel Inst. . .J. Laitdw. . . . .J. Oil Col. Chem. A:soc. .J. Opt. SOC. Amcr. . .J . Path. Bact. . .J. Pharmarcol. . . .J. Pharm. Chim. . .J. Physical Cheni. . .J. Physiol. . . .J. Physique. . . .J. Phys. Aadium . .J . Xoy. SOC. Testern Aus-tralia . . . .J. Buss. Phys. Chem. SOC. .J , Scientijc Gutruments .J . Soc. Chern. lnd. . .J . SOC. Dyers Col. . .J. SOC. Lerrthm Trades Chem.J . Soc. Phys. Chim. h’usse.Univ. Lesringrd . .J . S. Afr. Chem. Inst. .J. Tmt. Inst. . . .J . Washington Acad. Sci. .Klin. Woch. . . .Roll. Chcm. Beihefte . .Kolloid Z. . . . ,Landw. Jahrb. . . .Landw. Versuchs-Stat. .Mediz.h7aturwiss Arch. .Ment. COX Sci. Kyoto, .Mem. Dept. Agric. hdin .Mem. Munchester Phil. SOC.J. PT. Chcm. . -Mbm. SOC. €2. Sc;. Lie’ge .Mikrochein. . . .Min. Mag. . . . .dlonatsh. . . . .Naturwiss . . . .P . . . . . .Papierfabr. . . .Perf. Ess. Oil. Rcc. . .Pfliiger’s Archiv. . .JO u RNA L.Jonrnal of the Franklin Institute.Journal of General Physiology.Journal of Geology.Cliishitsugaku %asshi (Journal of the GeologicalQuarterly Journal of the Indian Chemical Society.Journal of the Indian Institute of Science.Journal of Industrial Hygiene.Journal of the Institute of Brewing.Journal of the Institute of Metals.Journal of the Iron and Steel Institute.Journal fur Landwirtsahaft.Journal of the Oil and Colour Chemists’ Association,Journal of the Optical Society of America.Journal of Pathology and Bacteriology.Journal of Pharmacology and Experimental Thera-Journal de Pharmacie et de Chimie.Journal of Physical Chemistry.Journal of Physiology.Journal de Physique.Journal de Physique e t Ic Radium.Journal fur praktische Chemie.Journal of the Royal Society of Western Australia.Journal of the Physical and Chemical Society ofJournal of Scientific Instruments.Journal of the Society of Chemical Industry.Journal of the Society of Dyers and Colourists.Journal of the Society of Leather Trades’ Cliemists.Journal de la SociBtk Physico - Chiniique Russe iJournal of the South African Chemical Institute.Journal of the Textile Institute.Journal of tl,e Washington Academy of Sciences.Klinische Wochenschrift.Kolloidchemische Beihefte.Kolloid -2eitschrift.Landwirtschaftliche Jahrbucher.Die Landwirtschaftliclien Versuchs-Stationen.Medizinisch-naturwissenscliaftliclies Archiv.Memoirs of the College of Science, Kyoto ImperialMemoirs of the Department of Agriculture in India.Memoirs and Proceedings of the Manchester LiteraryMkmoires de la Socikt6 R.des Sciences de LiBge.Mikrocheniie.Mineralogical Magazine and Journal of the Mineralo-gical Society.Monatshefte fur Chemie nnd verwandte Theile andererWissenschaften.Die Naturwissenschaften.% Proceedings of the Chemical Society.Papier - Fabrikan t ,Perfumery and Essential Oil Record.Archiv fur die gesamte Physiologie des Menschen undSociety of Tokyo).peu tics.Russia.l’Universit6 de Leningrad.University.and Pliilosophicnl Society.der Thiere.Pharm..J . . . . , Pharmaceutical Journal.Pharnt. Weekblad . . Pharmaceutisch WeekbladTABLE OF ABBREVLATIONS EMPLOYED IN THE REFERENCES. ixABBREVIATED TITLE.I’harnz. Zlg. . . .PJmrm. Zentr. . . .Ph71. Mag. . . .Phil. Tram , . .Pliysical Rev. . . .Physikal. Z. . . .Proc. Acad. Nut. Sci. P?da-delphia . . . .Proc. Camb. Phil. Soc. .Proc. Cotorado Bci. SOC. .Proc. Indiana Acad. Sci. .Proc. K. Akad. IVefoLsch.Proc. Nut. Acnd. Sci. , .Proc. Physical SOC. . .Proc. Roy. Soc. . . .Proc. Boy. SOC. Zdin. . .Proc. 80s. Exp. Biol. Ale(/. .Proc. U.S. Xnt. Museum .Quart. J. E,tp. Physiol. .Quart. J . Jifcd.. . .Aec. trav. chim. . . .AmsterdamRend. Accad. Sci. Pis. Mat.Napoli . . . .Rep. Imp. Ind. Aes. Instit.Osaka, Japan. . .Repert. Pharm . . .Rev. gCn. Coll. . . .Rev. 9th. Sci. . . .Iiocz. Chcna. . . .Sci. Bep. TGAoku Imp, Uniu.A’it;?6?igsber. Ges. Befiirdcr.ges. Nahrwiss. Marburg .Sitrungsber. Preuss. Akatl.IViss. Berlin , . .Skan. Arch. Pliysiol. . .Soil Sci. . . . .Stnhl ‘zc. Eiscn . . .Svansk.Farm. Tids. . .Tech. Iiep. TdhokuIrnp. Gniu.Tids. Kemi Bergvaesen .Trans. Amer. EZeclrochem.SOC. . , . .Trans. Ceram. Soc. . .Trans. Faradny Soc. . .Univ. Toronto, Sch. Eng.Res. Bull. . , .Univ. Toronto Studies. Geol.Ser. . . . .U.X. Dept. Agric. B d I . .Z. anal. Chem. . . .2. angew. Chem.. . .Z. anorg. Chem., . .2. Eleklrochent. . . .2. Krist. . . . .JOURNAL.Pharmazeutische Zeitung.Pharmazeutische Zentralhalle.Philosophical Magazine (The London, Edinburgh andDublin).Philosophical Transactions of the Royal Society ofLondon.Physical Review.Physikalische Zeitschrift.Proceedings of the Academy of Natural Sciences ofProceedings of the Cambridge Philosophical Society.Proceedings of the Colorado Scientific Society.Proceedings of the Indiana Academy of Science.Koninklijke Akadeniie van Wetenschappen te Amster-dam. Proceedings (English version).Proceedings of the National Academy of Sciences.Proceedings of the Physical Society of London.I’roceediiigs of the Royal Society.Proceedings of the Royal Society of Edinburgh.Proceedings of the Society for Experimental biologyProceedings of the United States National Museum.Qnarterly Journal of Experimental Physiology.Quarterly Journal of Medicine.Recueil deu travaus chimiques des Pays-Bas et de laItendiconto dell’ Academia delle Scienze Fisiche eIJLeports of the Imperial Industrial Research Institute,Repertorium der Pharmazie.Revue ghbrale des Colloides.YLevue g(tn6rale des Sciences pures et appliqndes.Roczriiki Cheniji organ Polskiego TowarzystwaScience Reports, Tbhoku Imperial University.Sitzungsbericlite der Gesellschaft zur BefiorderungSitzungsberich tc der Preussischen Altademie derSkandinavisclies Archiv fur Physiologie.Soil Science.Stahl untl Eisen.Svensk Fnrmaceutisk Tidskrift.Technology Reports of the TBhoku Imperial Univer-Tidsslirift for Keini og 13ergvaesen.‘l’ransaetions of the American ElectrochemicalTransactions of the Ceramic Society.Transactions of the Faraday Society.University of Toronto School of Engineering Research,University of Toronto Studies, Geological Series.United States Department of Agriculture Bulletins.Zeitschrift fiir analytische Chemie.Zeitschrift fur angewandte Chemie.Zeitschrift fur anorganische und allgemeine Chemie.Zeitschrift fiir Eloktrochemie.Zeitschrift fur Krystallographic.Philadelphia.and Medicine.Belgique.Matenlatiche Napoli.Osaka, Japan.Cliemicznego.der gesam ten Natur~isseiischaften zu Rl arburg.Wissenschaften zn Berlin.sity, Sendai, Japan.Society.Bulletin.AX TABLE OF ABBREVIATIONS EMPLOYED IN THE REFERENCES.AnBliEVIATED TITLE.Z.MetnTLlc. . . .2. PJanz. Dung. .2. Physik . . .Z. phpikal. Chem. .3. phyoiol. Chem. .Z. tech. Physik . .2. Unters. Nalw.-GeizeLsnn2. Vw. Deut. Zucker Ind.2. wiss. Photochem. .2. Zuckerind. Czechodov.JOURNAL. . Zeitschrift fur Metallkunde. . Zeitschrift fur Pflanzenernrihrung und Diingimg. . Zeitschrift fiir Pliysik. . Zeitschrift fiir physikalische Chemie, Stochiometrie. Tloype-Seyler's Zeitschrift fur pliysiolosgiche Chemie. . Zeitsclirift fiir tecliiiisclio Pliysik. . Zeitschrift fur Untersuchung der Nahrungs- und. Zeitschrift des Vereins der deutschen Zuclrer-. Zeitschrift fur missenscl~aftliche Photographie, Photo-. Zeitschrift fur Zuckerindustrie dcr Ceclioslovakisclienund Verwandtschaftslehre.Genussniittel.Industrie.physik und Photochemie.Republik

ISSN:0365-6217    

DOI:10.1039/AR9252200001

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

ANNUAL REPORTSON THEPROGRESS O F CHEMISTRY.GENERAL AND PHYSICAL CHEMISTRY.The Velocity of Chemical Reactions.THE difficult fundamental problems of the kinetics of chemicalreactions have continued to attract much discussion and experi-ment. The accepted view that reaction occurs through the agencyof activated molecules which have acquired a critical incrementof energy over the average tends to become more definite by theidentification of activated states with higher quantum states of themolecule, and a solution of the problem may be expected to followthe further development of our knowledge of quantum mechanicsas it affects the energy exchange between molecules.R. C. Tolman 1 points out that the well-known expressions foruni- and bi-molecular reactions : -dC/dt = kC = k’e--E/RTC, and- dC/dt = kCC‘ = k’dT .e-(E+E’)IRTCC’, have previously beendeduced only by assuming some possible but not inevitable mechan-ism, one fast enough to maintain the full Maxwell-Boltzmann quotaof active molecules in the reacting system or one involving radi-a t i ~ n . ~ By a mathematical analysis based on the “principle ofmicroscopic reversibility ” * he derives these equations withoutassuming any specific mechanism, and concludes that they givethe energy of activation under a wider variety of conditions thanhave hitherto been considered.The main problem is to find a mechanism of energy transfer1 J . Amer. Chem. SOC., 1925, 47, 2652.2 €4. Marcelin, Ann. Pihysique, 1915, [ix], 3, 120; A., 1915, ii, 328; J.Rice,Brit. Assoc. Reports, 1915, 397; W. H. Rodebush, J . Amer. Chem. SOC.,1923, 45, 606; A., 1923, ii, 303; J. A. Christiansen and H. A. Kramers,2. physikal. Chem., 1923, 104, 451 ; A., 1924, ii, 28.J. Perrin, Ann. Physique, 1919, [ix], 11, 5 ; A., 1919, ii, 177; W. C. McC.Lewis, J., 1918, 113, 471 ; Phil. Mag., 1920, [vi], 39, 26; A , , 1920, ii, 100.4 “ If we have a system in statistical equilibrium, the principle requiresnot only that the number of molecules in any given state shall remain con-stant, but that the number leaving that state in unit time by any particularpath shall be made up by the entrance of an equal number of molecules by thereverse of that partidar path ” (R. C. Tolman, Zoc. cit.).A* 12 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.adequate to supply activated molecules a t least as fast as they areused up by reaction.The position has been reviewed by M. Boden-stein,5 R. C. Tolman,6 and others.' In a purely thermal homo-geneous gas reaction activation may be effected (a) by collisions,( b ) by absorption of radiation. The simplest view is that activationresults from the inelastic collision of two molecules of sufficientlyhigh energy of translational motion relative to each other, thelatter being converted into internal energy of activation. In abimolecular change A + B = AB, reaction may depend on collisionbetween * (a) A* + B, or ( b ) A* + B*, or ( c ) A + B, in the last caseboth being activated by the collision itself. Tolman finds that thedata for well-defined second-order reactions are compatible with( b ) and (c), not with (a), but regards this as no proof of activationby collision.C. N. Hinshelwood lo regards the experimentalevidence as definitely in favour of ( c ) , the heat of activation, E,being a real measure of the relative kinetic energy that the moleculesmust possess in order that reaction may occur on collision. Onthe other hand, activation by simple collision has been proved tobe very far from adequate to maintain unimolecular reactions.The chance of two molecules of nitrogen pentoxide colliding withthe high energy of 24700/N cal. is very small. The view recentlyput forward by Sir J. J. Thomson l1 that certain molecules accumu-late by collision sufficient energy to cause dissociation implies anaccelerating effect by an inert diluent, which is contrary to recentobservation. l2The failure of simple collisions to account for the high rates offkst-order reactions accompanied by such large energy of activationled J.A. Christiansen and H. A. Kramers l3 to propose the " hotmolecule " theory whereby molecules are activated mainly bycollisional transfer of the heat of reaction ; thus for a unidirectionaldecomposition (regarded as exothermal) : AB (AB)* + [A* +B*]+A + B. The complex of resultants immediately after spon-taneous decomposition of (AB)* contains the heat of reaction as wellZ. Elektrochem., 1925, 31, 343.J . Arner. Chern. SOC., 1925, 47, 1524; A., ii, 799.A* signifies an activated molecule of A.' E.g., G.N. Lewis and D. F. Smith, ibid., p. 1508; A., ii, 799.9 LOG. cit.lo C. N. Hinshelwood and J. Hughes, J., 1924, 125, 1841; C. N. Hin-shelwood and R. E. Burk, Proc. Roy. SOC., 1924, A, 108,284; A . , 1924, ii, 751 ;C. N. Hinshelwood and C. W. Thornton, Phil. Mag., 1925, [vi], 50, 1135;Ann. Report, 1924, 11.l1 Phil. Mag., 1924, [vi], 47, 337; A., 1924, ii, 222.l2 See also criticisms by J. Rice, Trans, Puruduy BOG., Oct., 1925;l3 LOG. cit., Ref. 2.A,,ii, 1076 (part of a general discussion on photochemical reactions)GENERAL AND PHYSICAL CHEMISTRY. 13as the original energy of activation. This high-energy product(" hot molecule ") can then revert to normal by transfer of itsexcess energy to the reactant AB on collision, thus activating it,and so on.These reaction chains may be started by ordinaryhigh-energy collisions. There is strong experimental evidencethat such high-energy molecules can exist, and transfer theirenergy in this way.14 The theory leads to velocity equations ofthe right form, e.g., for a unimolecular reaction :-dC/dt = kC =AC* = A(p*/p)e-ElzTC, where C and C* are the concentrationsof the normal and activated reactants, respectively, p and p* thecorresponding a priori probabilities l5 of these states (p*/p is notvery different from unity), while A is the probability per secondthat an activated molecule will decompose ( l / A , the mean life-period of the latter, is about sec.). Although there is goodevidence that molecular chain mechanisms actually occur in somereactions, difliculties arise which appear to rule this out as a generalexplanation.lG Thus to keep a first-order course each decornpos-ition must be immediately followed by activation of reactant inorder to maintain the same statistical equilibrium A B e (AB)* aswould obtain in the absence of reaction, which involves the highlyimprobable assumption that the " hot molecule," in spite of itsnumerous collisions with indifferent molecules, preserves its highenergy content until it meets a reactant.The unimolecular rate ofdecomposition of nitrogen pentoxide is not influenced by di1uents.l'There is also the objection that decompositions are endothermic, sothat supplementary activation would appear to be necessary ;J. Rice l8 has, however, given reasons for doubting the validity ofthis criticism.No form of collision theory alone appears to beadequate in the case of unimolecular reactions.The only alternative is activation by absorption of radiationpresent in temperature equilibrium with the system. The well-known Lewis-Perrin theory l9 of activation by selective absorptionof radiation of frequency v ( A + hv +A*, and E = Nhv per mol.)l4 See, e.g., 0. Klein and S. Rosseland, 2. Physik, 1921, 4, 46; A., 1921,ii, 291; J. Franck, ibid., 1921, 4, 89; 1922, 9, 259; A., 1922, ii, 464; G.Cario and J. Franck, ibid., 1922, 11, 161 ; A,, 1922, ii, 809.15 " The a priori probabilities take account of the fact that each quantumstate of dehite energy content of a molecule may be realised in differentways, the p's representing the number of possible modes of realisation of eachstate" (A.C. McKeown, Phil. Mag., 1923, [vi], 46, 323).la R. C. Tolman, ref. 6; M. Bodenstein, ref. 5; G. N. Lewis and D. F.Smith, ref. 7; J. Rice, ref. 12.18 J. Rice, loc. cit., ref. 12.19 Trans. Paraday SOC., 1922, 1'7:l7 See refs. 33.Discussion on the Radiation TheorySee also a review of radiation theories by of Chemical Action, p. 545 et seq.H. S. Harned, J. B'ranklin Inst., 1923, 196, 1811.1 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.has been abandoned because the frequency predicted from thetemperature coefficient of reaction velocity does not in generalagree with absorption bandsY2O nor does it accelerate the reaction,and because activation by this means cannot occur with the speedrequired to account for known first-order rates.21 R.C. Tolman’scalculations 22 indicate, however, that this mechanism is a possibleone for bimolecular reactions. Attempts to improve the radiationtheory 23 found less favour than theories of collision, but on accountof the difficulties of the latter, especially as regards unimolecularreactions, attention has again been focussed, by G. N. Lewis,R. C. Tolman, E. K. Rideal, J. Rice, and others, on radiation as themost probable activating agency. T ~ l m a n , ~ ~ reviewing the varioussuggestions for a less restricted radiation theory, finds most promis-ing the view that, on the assumption of a nearly continuous seriesof high energy quantum states corresponding to the idea of theweakening of a chemical bond, energy may be absorbed over acontinuous range of frequencies, thus allowing an ample inflow.Somewhat similar ideas had been expressed by E.K. Rideal andW. C. McC. Lewis. G. N. Lewis and D. F. Smith,25 who support a“ general ” radiation theory, employ the concept of discrete lightquanta of relatively large size, thus facilitating collisional exchangeof energy between molecules and quanta. J. Rice 26 has subjectedthese latter developments to a searching criticism, without, how-ever, questioning the necessity of some form of radiation theory.These more recent views have not yet been formulated withsufficient precision for experimental test.W. E. Garner 27 maintains that the close agreement between thecritical increment from temperature coefficient with that calculatedfrom the kinetic theory ( E = 2 x total number of collisions xe-ElRT. P), assuming P == 1, i.e., every collision between activatedmolecules is “ fruitful,” cannot, as Hinshelwood 28 supposes, beaccepted as evidence that P is unity, or that the critical incrementfrom temperature coeEcient is the true energy of activation.20 The interesting observation has been made by W.T. David, Proc. Roy.Soc., 1925, A , 108, 617; A . , ii, 980, that the rate of explosion of gas mixturesis increased when the infra-red radiation superimposed on that emitted bythe burning gases is of the type that can be absorbed by the gases.21 J. A. Christiansen and H. A. Kramers, ref.2; R. C. Tolman, ref. 6.22 Ref. 6.23 See ref. 19 and R. C . Tolman, J . Amer. Cham. SOC., 1920, 42, 2506;1921, 43, 269; A., 1921, ii, 99, 248; J. Perrin, ref. 3.24 Refs. 6 and 23; J. Rice, ref. 12.25 Ref. 7.26 Ref. 12.27 Phil. Mag., 1925, [vi], 49, 4G3; 50, 1031; A., ii, 552, 1167.28 Ibid., 1925, [viJ, 50, 360; A., ii, 874.See also S. C. Roy, Z. Plqsili, 1925, 34, 400; A., ii, llG7GENERAL AND PHYSICAL CHEMISTRY. 15M. Born and J. Franck29 stress the importance of attackingproblems of chemical kinetics from the point of view of the Bohratom and the quantum laws of energy exchange. They considerthat in the collision reaction A + B+ C* + C + Q (heat ofreaction), the fact that the primary complex, C*, formed at themoment of collision contains Q plus the relative kinetic energy, X ,of A and B before collision does not of itself, as has often beenassumed, prevent the formation of C, for molecules can existtemporarily having a quantised energy content much greater than &.What does, however, prevent the formation of C is the infinitelysmall probability that Q + X will agree with any quantum state( X being continuous).The energy of this incompletely quantisedprimary molecule (or " quasi-molecule ") can adjust itself to adiscrete value neither by radiation nor conversion into translationalenergy, consequently C can be formed only if, during the period ofcollision, the complex is struck by a third atom or molecule, whichcarries off the excess energy (heat of reaction) as kinetic energy oftranslation, thereby converting C* into C.Such ternary collisionsare evidently unnecessary in the reaction type AB + C -+ AC + B,since the continuous energy of translation is available for adjust-ment to a definite quantum state, and it is suggested that thecatalytic effect of water vapour may be associated with a transitionfrom the addition to the relatively faster exchange type of reaction.They are also unnecessary in the addition type when one reactantis large enough for the quantum states to be practically continuous.Surface catalysis provides an extreme example of the latter ; whenB strikes adsorbed A, energy adjustment to the appropriate quantumstate can be established by the continuous energy reservoir of thesolid catalyst.M. Polhyi and E. WignerY3O while admitting themechanism of ternary collision, differ from Born and Franck inregarding the probability of combination resulting from binarycollision as finite, though small. M. Bodenstein31 points out thatthe ternary collision theory suggests an acceleration of reaction inthe presence of inert gases, which is not in accord with experiment.Whilst the existence of homogeneous bimolecular gas reactionsfree from " wall effect,s " has been established, the fact that reputedexamples of such unimolecular reactions have proved to be notindependent of surface/volume ratio or of pressure has led to seriouadoubts as to their actual existence. Thus the best defined example,that of the thermal decomposition of nitrogen pentoxide, was29 2.Physik, 1925, 31, 411; A., ii, 266; Ann. Physik, 1925, [iv], 76, 225;A., ii, 365; J. Franck, 2. Elektrochem., 1925, 31, 350; Natumuiss., 1924, 47,1063; A., 1925, ii, 836.30 2. Physik, 1925, 33, 429.31 Ref. 516 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.apparently catalysed by nitrogen peroxide.32 In view of its greattheoretical importance, this reaction has been carefully re-examinedby four independent investigator^,^^ who agree in finding no evidenceof catalysis or wall-effect and no variation of rate ( a ) over an enor-mous range of pressure down to less than 1 mm., (b) in the presenceof excess of argon, air, and nitrogen peroxide. Further, the rate ismuch the same in inert solvents over wide concentration ranges.=The absence of any retarding influence of diluents or of very lowpressures renders improbable any chain mechanism. According toH.S. Hirst and E. K. Ridea1,35 however, who worked a t pressuresdown to 0.01 mm., the rate, constant above 0.25 mm., begins toincrease a t this critical pressure, approaching a limiting valuefive times the normal as the pressure diminishes. This limitingvalue is in remarkably close agreement with the Dushman-Rideal 36equation :--dC/dt = ve-shv/RT. C, which suggests some form ofradiation mechanism of activation. The reaction is consideredto take the following course : one-fifth of the activated moleculesalways decompose independently of pressure, whilst four-fifthsdecompose only if, after activation, they fail to collide during aperiod of about 10-6 second (collision within this period causessimple de-activation).There seems to be no reason for doubtingthe unimolecular homogeneous character of this reaction.D. F. Smith 37 finds that the thermal decomposition of sulphurylchloride, which has been stated3* to be a wall reaction, is a first-order reaction independent of surface/volume ratio except to aslight extent at lower temperatures. According to D. L. Watson,39the thermal decomposition of four derivatives of oxalacetic esterin the pure liquid phase follows a unimolecular course, and inertsolvents are without influence on the velocity coefficients. Thephenyl derivative decomposes autocatalytically. It is shown that,by molecular chain activation, first-order reactions should be auto -32 F.Daniels and E. H. Johnston, J . Amer. Chem. SOC., 1921, 43, 53; A.,1921, ii, 249; R. H. Lueck, ibid., 1922, 44, 757; A., 1922, ii, 433; F. Daniels,0. R. Wulf, and S. Karrer, ibid., 1922, 44, 2402; A . , 1923, ii, 24.33 J. K. Hunt and F. Daniels, ibid., 1925, 47, 1602; A., ii, 801 ; E. C.White and R. C . Tolman, ibid., 1925, 47, 1240; A., ii, 682; H. S. Hirst, J.,1925, 127, 657; H. S. Hirst and E. K. Ridoal, Proc. Roy. SOC., 1925, A , 109,526.34 R. H. Lueck, ref. 32.36 S. Dushman, J . Amer. Chem. SOC., 1921, 43, 397; A . , 1921, ii, 315;E. K. Rideal, Phil. Mug., 1920, [vi], 40, 461; A., 1920, ii, 676; J. Rice,ibid., 1923, [vi], 46, 312; A., 1923, ii, 622; A. McKeown, ibid., 1923, [vi],46, 321 ; A., 1923, ii, 623.35 Ref.33.37 J . Amer. Chem. Xoc., 1025, 47, 1862; A . , ii, 876.38 C. N. Hinshelwood and C. R. Prichard, J., 1923, 123, 2725.39 Proc. Roy. SOC., 1925, A , 108, 132; A., ii, 556.see C. N. Hinshelwood, J., 1920, 117, 156; 1921, 119, 721.For similar reactionsGENERAL AND PHYSICAL CHEMISTRY. 17catalytic, and this is considered to be the essential character of allfour reactions. The thermal decomposition of ozone 40 is mainlyhomogeneous (second order), but not free from wall effect. Oxygenretards and indifferent gases accelerate the reaction. The mechan-ism proposed is : 0,e03* ; 03* + 0,e-Complex ; Complex +30,' it being assumed that the complex may break up into 0, or0, either spontaneously or on collision ; collision with oxygenfavours Complex + O,, and collision with an indifferent gas favoursComplex + 0,.This mechanism includes the possibility of mole-cular chain activation and Born-Franck ternary collisions.Theories which provide for energy transfer adequate to maintainknown reaction rates touch but one aspect of the question. Theenergy of collision in gases dried to inertness is presumably notaltered in the presence of minute traces of water, and in this sensemost reactions are catalytic. This point has been emphasised byR. G. W. NorrishY4l who considers that the inert " dry molecules "are partly activated by close association with water, which, in virtueof its high polarity, weakens the structure of the " resting '' mole-cule, so that the supplementary activation necessary for reactionmay be attained by collision.The catalytic activity of surfaces isdue to similar causes, non-polar surfaces such as paraffin wax beingnon-catalytic. The rate of photochemical union of hydrogen andchlorine is independent of the pressure of water vapour down toloe4 mm., when it begins to fall, reaching zero a t lo-' mm. water-vapour pressure.42 This corresponds to a gradual removal of thewater film. It is therefore suggested that the removal of thiscatalytically active film rather than " ultra-dryness " of the gasesis responsible for the suspension of reactions of dry gases in general.Quantitative studies of moisture effect on reaction rate are muchneeded.Heterogeneous Catalysis and Adsorption.A very considerable amount of work on this subject has beendone since it was last noticed in these Reports.43 I.Langmuir'swell-known theory43 has on the whole been substantiated and is40 R. 0. Griffiths and A. McKeown, J., 1925, 127, 2086.*l J., 1923, 123, 3006; H. S. Taylor, J. Physical Chem., 1924, 28, 897.42 M. Bodenstein and W. Dux, 2. physikal. Chem., 1913, 85, 297; A., 1913,ii, 1039; A. Coehn and G. Jung, ibid., 1924, 110, 705; A., 1926, ii, 142;R. G. W. Norrish, J., 1925, 127, 2316; A., ii, 1179; Trans. Faraday XOC.,Oct., 1925; A., ii, 1080.43 See the Reports of the Committee on Contact Catalysis (NationalResearch Council), especially the second report : W. D. Bancroft, J. PhysicalChew&., 1923, 2'7, 801; and third report : H. 5. Taylor, ibid., 1924, 28, 898.An excellent account is given by H.S. Taylor in his " Text-book of PhysicalChemistry " (Macmillan, 1924). See also the discussion on catalysis, J .Paraday SOC., 1922, 17, 60718 ANNUAL REPORTS ON THE PROGRESS Ol? CHEMISTRY.very generally accepted. A consideration of kinetic studies, of theparallel investigation of adsorptive capacity and reaction rate fort’he same catalyst, and of work on catalyst surfaces has, however,led H. S. Taylor to a “ concept of the catalytic surface which is,perhaps, more comprehensive than earlier efforts and which leadsto interesting general conclusions with reference to matter in thesolid state.” It has been fully established that the Langmuiractive areas or centres occupy only a small fraction of the surface,that they vary in their capacity both to adsorb and promote reaction,and that metallic catalysts are extraordinarily sensitive to heattreatment and poisoning, but the consequent reduction of catalyticactivity greatly exceeds that of adsorptive capacity.To accountfor these facts, a modification of the Langmuir concept is proposed,and illustrated by reference to a metallic catalyst such as nickel.Whilst giving no information about the surface, X-ray examin-ation 45 shows that active catalysts prepared by low-temperaturereduction of oxides consist of fine granules having the definitelattice structure of the crystals. The mode of production andsensitivity to moderate heat treatment (incipient sintering) suggestincomplete surface crystallisation, i.e., occasional groups of atomsfixed in metastable positions associated with high energy andchemical unsaturation relative to the atoms in the regular latticebelow (Fig.l).46NiINi Gas Phase NiI 1Ni- Ni Ni-I I INi- Ni- Ni- Ni- Ni-I l l 1 1I. -Ni- Ni- Ni- Ni- Ni- Ni- Ni- Ni-Ni- Ni-Ni- Ni- Ni-11. -Ni- Ni- Ni- Ni- Ni- Ni- Ni- Ni-Ni- Ni-Ni- Ni- Ni-l l l l 1 1 . 1 I I I I l lGranule ProperFIG. 1.From layer I1 (where each Ni is surrounded by six others) out-wards, the degree of constraint or saturation decreases to a varyingextent, the “ peak ” atoms differing from gaseous atoms only bythe single valence which holds them to the solid. While a freeatom can bind four CO groups, a singly anchored atom may adsorbthree such groups (or their equivalent), and a doubly anchored,two.Corner and edge atoms of a crystal are also unsaturated to44 Proc. Roy. Xoc., 1925, A, 108, 105; A., ii, 562.4 j G. L. Clark, W. C. Asbury, and R. 31. Wick, J . Arner. Chem. Soc., 1925,46 Bigure taken from H. S. Taylor; ref. 44.47, 2661 ; R. W. G. Wyckoff and E. D. Crittenden, ibid., p. 2866GENERAL AND PHYSICAL CHEMISTRY. 19different extents. Reactants such as hydrogen and ethylene maybe held by the same Ni atom (Langmuir postulated adsorption ofreactants on adjacent centres). The rise of activity of platinumand silver in oxidation catalysis is due to surface disintegrationleading to an increased number of unsaturated atoms. Moderateheat treatment causes atomic displacement to a more regularsurface with loss of energy, the more mobile singly-bound andhighly active atoms being the more readily displaced.That thesaturation capacity of a surface varies for different adsorbed gasesis thus to be expected ; there are, for example,47 more copper atomscapable of holding carbon monoxide than hydrogen. At highertemperatures, adsorption is increasingly confined to the moreunsaturated surface atoms and it is t o these that poisons firstbecome atta~hed.~8 Correlating the adsorptive and catalytic powerof copper for the reaction C2H4 + H, = C2H,, R. N. Pease 49found that poisoning by mercury, whilst not appreciably affectingthe weaker (high pressure) adsorption, destroyed both the stronger(low pressure) adsorption and the catalytic activity, and a coppercatalyst which strongly adsorbed 5 C.C.of carbon monoxide suffereda 90% loss of catalytic activity by adsorbing only 0-05 C.C. of thispoison, which means that the surface owed 90% of its activity toless than 1% of its strongly adsorbing centres.5* Thus even low-pressure adsorption measurements may give no true index ofcatalytic activity. That the varying degree of saturation ofsurface atoms involves varying catalytic activity is well illustratedby the progressive poisoning experiments of G. Vavoii and A.H u s s o ~ , ~ ~ who found that when platinum had been poisoned bycarbon disulphide just sufficiently to suppress the hydrogenation ofdipropyl ketone, it could still hydrogenate piperonal and nitro-benzene, whilst a further dose of poison stopped the former, butnot the latter reaction, which again could be poisoned by morecarbon disulphide.The amount of active surface is thus deter-mined by the reaction catalysed.Support for the theory outlined above is found in the high valuesof heats of adsorption, e.g., of hydrogen on nickel 52 : 13,500--20,5004 7 R. N. Pease, J. Amer. CI:em. SOC., 1923, 45, 1106, 2235; A., 1923, ii, 472,4 8 See, e.g., data for hydrogen on nickel: A. W. Gauger and H. S.49 R. N. Pease, ibid., p. 2296; A . , 1923, ii, 862.50 R. N. Peaso and L. Stewart, &id., 1925, 47, 1235; A., ii, 691; see also13. B. Maxted, Trans. Puraday SOC., 1917, 13, 36; E. B. Armstrong andT. P. Hilditch, ibitl., 1922, 17, 669.6 1 C'ompt.rend., 1922, 175, 277; A . , 1922, ii, 631.52 R. A. Beebe and H. S. Taylor, J. Amer. Chern. Xoc., 1924, 46, 43; A.,1024, ii, 159; B. Foresti, Guzzetta, 1923, 53, 487; 1924, 54, 132; 1925, 55,185; A., 1923, ii, 747; 1924, ii, 320; 1925, ii, 692.842.Taylor, ibid., p. 920; A., 1923, ii, 39820 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.cal. per mol., depending on its history. E. A. Blench and W. E.Garner 53 find values for oxygen on charcoal varying from 60,000cal., a t low temperatures and high adsorptions, to the surprisinglyhigh value of 220,000 cal. a t high temperatures and low adsorptions.As expected, there is a greater heat effect for initial than for subse-quent adsorption. The heat of formation of carbon dioxide fromsolid charcoal, which includes the endothermal breaking of carbonlinkings, is 97,000 cal., whilst from gaseous carbon it is 380,000 ~ a l .~ ~The high heat of adsorption indicates that some carbon links onthe surface are already broken, yielding atoms in a highly un-saturated and active state, so that their combustion resembles thatof gaseous rather than of crystalline carbon. The fact that theheat of combustion of the incompletely crystallised charcoal exceedsthat of graphite is also in agreement with the theory. E. F. Arm-strong and T. P. H i l d i t ~ h , ~ ~ who have made a thorough study ofcatalytic hydrogenation at nickel surf aces, express general agree-ment with this theory, but consider that the acting nickel atommay at the moment of catalytic change be actually deta?ched fromthe metal as a complex of nickel, oil, and hydrogen, which breaksup with deposition of the nickel.According to A. W. Gauger,5spure nickel and platinum distilled in a vacuum on to the surfaceof glass wool are catalytically inactive, so that activity depends oncondition rather than on extent of surface. He regards the moleculesor atoms a t active centres as having electrons in energy levelshigher than normal. 31. Bodenstein 57 refers to deformation of suchadsorbed molecules.Special interest attaches to the investigations of W. G. Palmer 58and F. H. Constable 59 dealing mainly with the catalytic dehydro-genation of alcohols (vapour) in the presence of copper. Thereaction rate is independent of pressure over a 12-fold range,showing that reaction occurs only in the layer in immediate contactwith the copper.The primary alcohols, ethyl, propyl, butyl,isobutyl, and isoamyl, decompose a t the same rate (isopropyl53 J , , 1924, 125, 1288; Nature, 1924, 114, 932; A., 1925, ii, 140.54 K. Fajans, Ver. Deut. Physikal. Ges., 1913, 14, 324.5 5 Proc. Roy. SOC., ,1925, A, 108, 111 ; A., ii, 562.5 6 J. Anter. Chem. SOC., 1925, 47, 2278; A., ii, 1072.5 7 Annalen, 1924, 440, 177; A., 1925, ii, 216.5 8 W. G. Palmer, Proc. Roy. SOC., 1920, A, 98, 13; 1921, A , 99, 412; A . ,1920, ii, 609; 1921, ii, 542; D. M. Palmer and W. G. Palmer, ibid., p. 402;A., 1921, ii, 541; W. G. Palmer, ibid., 1922, A , 101, 175; A., 1922, ii, 437;W. G. Palmer and F. H. Constable, ibid., 1924, A, 106, 250; 1925, A , 107,255; A., 1924, ii, 843; 1925, ii, 311.59 F.H. Constable,ibid., pp. 270, 279; A., ii, 311; Nature, 1925, 116, 275;A., ii, 983; Proc. Roy. SOC., 1925, A , 108, 355; A., ii, 804; Proc. Cuinb.Phil. SOC., 1925, 22, 738; A., ii, 881GENERAL AND PHYSICAL CHEMISTRY. 21alcohol five times faster) and with the same temperature coefficient,indicating identical mechanism and energy relations. The adsorbedmolecules are oriented with the hydroxyl group only in closeassociation with the surface. At the active centres the OH groupis distorted so that the hydrogen atom readily oscillates to thecopper, a second atom of hydrogen of the -CH2*OH group breakingaway automatically with formation of aldehyde. The energy ofactivation is supposed to be concentrated in the hydrogen atom ofthe OH group.The catalyst, prepared by successive oxidationand reduction at low temperature, is perfectly reproducible and adetailed study leads to views concerning the nature of the surfacewhich differ in no essential respect from those of H. S. Taylor.The active centres form only a very small fraction of the totalsurface. They are associated with varying critical increments,most of the reaction occurring at the centres of low increment.A mathematical analysis of the process is given.The varying catalytic and adsorptive activity of different portionsof a charcoal surface has been studied by E. K. Rideal and W. M.Wright,GO who express views in close agreement with those ofTaylor and Constable.By measuring the rate of absorption ofoxygen and evolution of carbon dioxide by charcoal suspended inwater (a zero-order reaction), they find the active fraction of thesurface to be 0*38%, this being the ratio of the number of moleculesof poison just sufficient to stop the reaction to the number necessaryto saturate the surface. In the catalytic oxidation of organicacids, 40% of the surface is active.Much discussion has centred round the question as to whetherthe active substance in a metal catalyst is the metal or an oxide.Thus M. C . Boswell and his associates maintain that the incom-pletely removed oxygen in nickel granules is vital for their activity.Recent work 62 appears, however, to have proved conclusively thatthe active substance is nickel.It is unlikely that the complex phenomena of promoter actionwill be explicable by any one theory.W. W. Hurst and E. K.Rideal 63 ascribe the promoting action of palladium on copper tointerface effects, the molecules a t the boundary between two solidphases being in a specially active condition. The promoting actionof irreducible oxides on nickel in the reaction GO2 + 4H2 = CH, +61 See H. S . Taylor, Report on Contact Catalysis, ref. 43; M. C. Boswelland C. H. Bayley, J . Physical Chem., 1925, 29, 11; A., ii, 215.62 A. W. Gauger, J . Amer. Chem. SOC., 1925, 47, 2278; A., ii, 1072; H.Adkins and W. A. Lazier, ibid., 1924, 46, 2291 ; A., 1924, i, 1278; C. Kelber,Ber., 1924, 57, [B], 136, 142; A., 1924, ii, 243, 244.J., 1925, 129, 1317.J ., 1924, 125, 685, 69422 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.2H,O is attributed by S. Medsforth 64 to dehydration or decom-position of intermediate compounds, and to selective adsorpt)ion.E. F. Armstrong and T. P. Hilditch 65 consider the effect mainlydue to an increase of surface. W. W. Russell and H. S. Taylor 66find no proportionate increase of adsorption with catalytic activityof nickel when promoted by thoria, so that the effect is to renderthe surface more active rather than more extensive. In conformitywith Taylor’s theory of the catalytic surface, an irreducible oxideprevents coalescence (sintering) of the nickel atoms, its chief functionbeing thus to produce a larger number of unsaturated atoms ofhigh activity.R. W. G. Wy~koff,~’ by an X-ray examination ofammonia-iron catalysts promoted by potash and alumina, findsthat the latter prevent the growth of the iron crystals.W. A. Bone and G. W. Andrew G8 have investigated the catalyticoxidation of carbon monoxide a t a gold surface a t 300”. Thetheoretical mixture 2CO + 0, reacts a t a rate proportional to itspressure when the catalyst has reached its normal activity bycontinued reaction. This normal activity is strongly stimulatedby previous exposure to either reactant or by reaction in a mixturecontaining excess of either reactant, and greatly reduced by keep-ing a t room temperature or a t 300” in a vacuum. After such alter-ations it reverts to its normal activity on continued reaction in thetheoretical mixture.They consider, therefore, that whilst bothgases are “activated” by association with the surface, suchactivation is by no means strictly confined to the surface layer,but extends to the more deeply “occluded” gases. This is ofconsiderable interest in view of the general conviction that surfacecatalysis is determined by a single adsorbed layer.C. N. Hinshelwood69 and his associates have investigated theinfluence of catalytic surfaces (heatcd wires) on gas reactions whichare bimolecular in the homogeneous phase. If the active surfaceof the catalyst remains saturated with adsorbed molecules, thereaction rate is independent of pressure (zero order), and no con-clusion can be drawn as to the number of molecules involved inthe catalytic reaction.With small adsorption, however, thisnumber is given by the order of reaction measured in the usual way.Intermediate states give illusory results. Zero orders are given by64 J., 1923, 123, 1452.6 5 Proc. Roy. SOC., 1923, A , 103, 586; A., 1923, ii, 551.66 J. Physical Chem., 1925, 29, 1325.6 7 LOC. cit., ref. 45.68 PTOC. Roy. Soc., 1925, A , 109, 459.69 C. N. Hinshelwood and C. R. Prichard, Proc. Roy. SOC., 1925, A , 108,211; A., ii, 567; J., 1925, 127, 327, 1552; C. N. Hinshelwood and R. E.Burk, ibid., pp. 1105, 2896GENERAL AND PHYSICAL CHEMISTRY. 23NH31W and HIlAu ; first orders by N,OIAu, N201Pt, HIIPt, NH31Pt,NH3(Si02. The catalyst promotes rapid first-order reaction, e.g.,of N,O = N, + 0, by “accepting ” oxygen atoms which thenevaporate as molecules.It also accelerates reaction by loweringthe energy of a c t i ~ a t i o n , ~ ~ which (calculated in the usual way) isfrequently about half the bimolecular value. There is no justi-fication, however, for attaching any important significance to theratio 2 : 1. A similar ratio is obtained by H. A. Taylor 71 for thedecomposition of hydrogen iodide a t glass walls and in the homo-geneous phase. Kinetic studies of the reduction of carbon dioxideby hydrogen at the surface of hot platinum and tungsten wires byC. N. Hinshelwood and C. R. Prichard 72 lend strong support tothe theory of H. S. Taylor.The activating effect of a polar surface has been strikinglydemonstrated by R. G. W. Norrish.73 Both dry chlorine andbromine react with ethylene rapidly on glass, still more rapidly onstearic acid, and scarcely at all on paraffin wax.This is regardedas strong evidence that molecular activation depends on inducedpolarity by association with a polar molecule. This reaction has beenemployed as a measure of the polarity of various surfaces.74The Surfaces of Liquids.According to the Langmuir-Harkins theory of the orientedunimolecular layer, which has been so firmly established as regardslong-chain substances with a polar end-group on water, wheresurface concentration and pressure can be directly measured, theexcess surface concentration of a solution is similarly restricted toa unimolecular layer, and the surface tension of the solution is dueonly to the stray fields of force of the molecules in this layer.Thelatter state is obviously less simple than the and recentwork 76 suggests that the phenomena at the surfaces of solutionscannot always be interpreted in quite such a simple manner. I nthe absence of trustworthy direct methods of measuring surfaceconcentration, r, it has generally been calculated from the surfacetension, U, of a solution of concentration C by the Gibbs equation :I’ = - C/BT . d ~ / d C , a form which is valid only for ideal solutions.The area, A , per molecule in the layer, obtained by assuming it tobe unimolecular, is generally in sufficiently good agreement with70 See also C. N. Hinshelwood and B. Topley, J., 1923, 123, 1014.72 J., 1925, 127, 806, 1546.73 J., 1923,123, 3006; 1925, 127, 2318; 1926, 55.74 N.K. Adam, R. S. Morrell, and R. G. W. Norrish, J . , 1925, 127, 2793.75 F. G. Donnan, Brit. Assoc. Rep., 1923, 59.‘13 See, e.g., 5. Sugden, J., 1924, 125, 1167; Ann. Report, 1924, p. 8.J. Physical Chem., 1924, 28, 984; A., 1924, ii, 74524 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.expected values to confirm the theory, but conclusions as to thestate of the surface molecules based on these values of A are notalways so certain as in the case of insoluble films. Recent measure-ments indicate that the acetic acid molecule occupies 28% morearea at an air-water than a t a hydrocarbon-water interface,77 andthat whilst pyrogallol (air-water) occupies only 16% more area thanphenol, which stands vertical, the o- and m-dihydroxy-derivativesmust be considerably inclined to, and the p-derivative flat on thesurface, giving incompressible although not close-packed films.78Ih recent work the importance of employing the Gibbs equationin its exact form has been emphasised, and activities have beenused instead of concentrations. Except for very dilute solutions ofnon-electrolytes, the concentration formula gives quite erroneousresults.A. K. Goard and E. K. Rideal 79 find that with increasingactivity of phenol in aqueous salt solution (due to increase of saltas well as phenol concentration) the adsorption increases to a maxi-mum, leading to values of A and of surface thickness in excellentagreement with accepted values of the dimensions of the benzenenucleus.The adsorbed phenol is thus contained in a single layerof close-packed, vertical molecules. Although this film is probablythe chief factor in determining the surface tension, the latter isdefinitely influenced through the film by molecules below it, indi-cating (contrary to the Langmuir-Harkins theory) the operationof forces exceeding molecular dimensions.and others points in the samepdirection, while E. Edser 81 considersthat attractive forces may be appreciable over a range of manymolecular diameters from the surface. The foundation of thefilm as well as the film itself cannot be neglected in a completetheory of surface tension.Salt solutions having a higher surface tension than water arecovered, according to Langmuir, with a single layer of orientedwater molecules.According to recent measurements 82 on suchsolutions, based on the Gibbs equation (activities), the apparentthickness of this layer decreases considerably with increasing con-centration, the effect depending on the nature of the salt. This isdifficult to reconcile with the single layer theory. Various sug-gestions are made, e.g., that the increasing diffusion pressure of1610; A., ii, 771.The work of T. Iredale7 7 W. D. Harkins and H. M. McLaughlin, J. Amer. Chem. SOC., 1925, 47,7 8 W. D. Harkins and E. H. Grafton, &id., p. 1329; A., ii, 658.7* J., 1925, 12'7, 1668.8o Phil. Mag., 1923, [vi], 45, 108s; 1924, 48, 177; 1925, 49, 603; A . , 1923,81 Brit. Assoc. Fourth Report on Colloid Chemistry, 1922, p.40.82 A. K. Goard and E. K. Rideal, J., 1925,127, 1668; IV. D. Harkins andH. M. Me Laughlin, J. Amer. Chem. SOC., 1925, 47, 2083; A , , ii, 959.ii, 379; 1924, ii, 663; 1925, ii, 508GENERAL AND PHYSICAL CHEM1S”RY. 25the ions forces them nearer the surface and thus perhaps modifiesthe orientation of the water molecules, and that the water shellof the ions becomes smaller or more tightly packed with increasingconcentration.The equation of state proposed by Langmuir g3 (following J.Traube) g4 for the “Gibbs layer” is FA = RT, where F , thesurface pressure, is the excess surface tension of the solvent overthat of the solution, and A is the area occupied by a gram-moleculeas surface excess. This two-dimensional analogue of the ideal gaslaw, whilst approximately valid for low values, fails at high valuesof F , suggesting a behaviour similar to that of compressed gases.R.K. Schofield and E. K. Rideal,s5 using the Gibbs formula(activities), find that for aqueous ethyl alcohol, with increasingconcentration, A first diminishes to a minimum, which is onlyslightly larger than the value corresponding to a close-packed film,then rises to a steady value three times the minimum for somereason not fully explained. Pyridine at a water-mercury inter-face shows similar behaviour. When, for aqueous solutions offatty acids, C, to C,,, a t benzene-water as well as air-water inter-faces, FAIRT is plotted against F , curves strongly resemblingthe corresponding ones for highly compressed gases are obtained,leading to P(A - B) = xRT as the equation of state of the surfacelayer for high values of F.B (compare b of the gas equation) isthe minimum area of an adsorbed gram-molecule under high surfacecompression, and 1 /x represents the lateral molecular cohesion,which increases with length of the carbon chain. This cohesion isgreatly reduced when the chains are in a hydrocarbon phase. Forsucrose at a water-mercury interface, x = 1 (no cohesion), givingthe exact analogue of the Sackur osmotic pressure equationP(V - b ) = RT, and the value of B, which is in striking agree-ment with the dimensions of the molecule from other sources,indicates that its long axis lies in the plane of the interface. Thegeneral conclusion is reached that the molecules adsorbed in aunimolecular layer from a weak solution affect the surface tensiononly by their thermal agitation. “At a given temperature theireffectiveness depends solely on their surface concentration, inter-facial areas, and lateral cohesion.” M.Volmer and P. Mahn&rt,86from direct measurements of the amount of benzophenone adsorbedfrom a crystal on the surface of mercury, obtain the same equationof state. It has also been deduced theoretically by S. C. Kar.8’83 J. Amer. Chem. Soc., 1917, 39, 1848; A., 1917, ii, 525.84 Annalen, 1891, 265, 27; A . , 1891, 1468.8 5 Proc. Roy. Soc., 1925, A , 109, 57; A., ii, 960; Nnlure, 1925, 116, 8%.a6 2. physikal. Chem., 1925, 115, 239; A., ii, 508.Physikal. Z., 1925, 26, 615; A., ii, 104526 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.An equation of this kind had previously been shown by N.K.Adam *8 to represent the behaviour of expanded films of insolublefatty acids.Organic vapours are reversibly adsorbed on mercury surfaces,giving, according to T. Iredale,8g unimolecular films. The con-siderable drop of surface tension caused by condensation from anearly saturated vapour indicates that the interfacial tensionbetween two liquids is not due exclusively t o the arrangement of asingle layer of molecules, but results from attractions extendingthrough a layer many molecules thick. Iredale's mode of usingthe drop-weight method has been adopted by othersg0 as beingmore rational than that of J. L. R. Morgan and W.D. Harkins.The continued study of long-chain surface films by N. K. Adam 91has shown that methyl esters of the alcohols do not form stablefilms, the methyl radical destroying the anchorage of the polargroup on water, and that with sufficient complexity of the mole-cular heads (e.g., the substituted ureas), a " two-dimensionalallotropy " occurs, depending on different types of packing in thefilm, and associated with a definite transition temperature. Penta-erythritol tetrapalmitate exists as a stable film with its four longchains parallel and perpendicular to the surface.A. P. Cary and E. K. Rideal,92 by placing crystals or lenses oflong-chain fatty acids and esters (instead of the usual solutionin a volatile solvent) on the surface of water, find that surfacesolution occurs, not by bulk spreading, but from the edge of contactof the lens or crystal,93 and a t a measurable rate until kineticequilibrium is reached between the substance and the film.Theprocess is reversible and occurs in two stages, first the productionof an expanded film under zero compression, F =crwater-um ;secondly, its condensation to an equilibrium pressure, F,, character-istic of the substance. The system is then the two-dimensionalanalogue of a saturated solution in equilibrium with the solidsolute. Contrary to the conclusions of A. Mar~elin,~~ there is a8 8 Proc. Roy. Soc., 1922, A , 101, 516; A., 1922, ii, 687; Ann. Report, 1923,I>. 22.Ref. 80.00 See A. K. Goard and E. K. Rideal, J., 1925, 12'9, 780.91 Summarising paper : J .Physical Chem., 1925, 29, 87; A., ii, 195;N. K. Adam and J. W. W. Dyer, Proc. Roy. SOC., 1924, A , 106,694; A., 1925,ii, 32.92 PTOC. Roy. SOC., 1925, A , 109, 301, 318, 331; A., ii, 1046-1048; Nature,1925, 115, 457; A., ii, 388.93 M. Volmer and P. Mahnert, Zoc. cit., find that benzophenone spreadsfrom a crystal placed on mercury directly, and not by vaporisation or bulksolution.94 Compt. rend., 1921, 173, 38; A., 1921, ii, 488GENERAL AND PHYSICAL CHEMISTRY. 27limit to the expansibility of the film due to the mutual attractionof the carbon chains. With increasing temperature dFe/dT has aconstant positive value through a considerable range, including thatover which the film changes from the condensed to the expandedstate. At the melting point of the crystal it changes sharply,becoming in some cases zero, in others negative, and finally aftera transition point less negative.The curves for different sub-stances are straight lines, generally parallel. The breaks areattributed to expansion of the lens-water interfacial film. Filmexpansion is regarded as due to hydration of the polar heads,this effect being opposed by attraction of the hydrocarbonchains for each other. An application of the Clapeyron equationto the two-dimensional system gives the latent heats of the changes,including approximately correct values of the latent heats of fusionof the crystals.The question of the rate of evaporation of water through a filmof insoluble fatty acid has been discussed. The conclusion ofG.Hedestrandg5 that such a film has no retarding effect has beenrefuted by N. K. Adamg6 and by E. K. Rideal,97 who has shownexperimentally that considerable retardation occurs, the effectbeing increased by an increase in surface concentration.Sir William Hardy,98 in a lecture to the Chemical Society, hasdiscussed the problems of interfaces. His well-known work onlubrication leads to the view that the surface forces responsiblefor the primary unirnolecular layer of oriented molecules on asolid, although acting directly over ranges comparable with moleculardimensions, are nevertheless by some means transmitted over muchgreater distances through secondary films, which, possibly onaccount of induced polarity, themselves are structured to a graduallydecreasing extent owing to the operation of thermal agitation.The essential differences between primary and secondary layers,and the factors governing their formation have been summarisedby Cary and Rideal.ggStrong Electrolgtes.Previous Reports have indicated that in recent yews the attemptto interpret the properties of solutions of strong electrolytes interms of a degree of dissociation measured by the conductivityratio has been abandoned.Instead much effort is being devotedto the exact determination of the thermodynamical properties of5 1 ~ J . Physz'cccl Chenz., 1924, 28, 1245; A., 1925, ii, 102.9 G Ibid., 1925, 29, 610; A., ii, 658.9g J., 1925, 127, 1207; Brit. Assoc. Fourth Report on Colloid Chemistry,9 7 Ibid., 1925, 29, 1585.1922, 18.5.LOC.cit., ref. 92, p. 30128 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.solutions, and for their expression the activity concept of G. N.LewisIt may perhaps be emphasised here that activities are not, asthey have been often regarded, empirical quantities which mustbe inserted into the theoretical equations in place of concentrations,in order to produce the observed results. They are in fact exactexpressions of the partial free energies of substances in solution. If AFis the free energy change (per mol.) in the transfer of a substance froma solution in which its concentration is c to a second solution in whichits concentration is co, then the ratio of the corresponding activitiesis given by AF = RT log, a/ao.If the solution were “ ideal,” thefree energy change in the transfer would be AF = RTlog, c/co.Now if the second solution be that which has been chosen as standard(usually an infinitely dilute solution), we may put a. = co, sinceonly the ratio of the activities has been defined. It is now evidentthat a/c, which is known as the activity coefficient f , is a measureof the deviation from the ideal relation.A number of important measurements of activities have appearedduring the year, among which the following may be mentioned :sodium hydroxide in aqueous solution,2 sodium hydroxide insodium chloride sol~tions,~ potassium hydroxide in potassiumchloride solution^,^ water in sodium chloride and potassium chloridesolution^,^ sulphuric acid in aqueous sulphate solutions,6 hydrogenchloride in ethyl-alcoholic s~lution,~ hydrogen chloride in methyl-alcoholic solution,s calcium, strontium, and barium chlorides inaqueous sol~tion,~ barium chloride in aqueous solution, lo hydrogenfluoride in aqueous solution.ll G.Scatchard has redetermined theactivities of hydrogen chloride in aqueous solution l2 and hasrecalculated the activities of potassium, sodium and lithium chlor-1 G. N. Lewis and M. Randall, “Thermodynamics and the Free Energyof Chemical Substances,” McGraw, Hill Book Co., 1923. Compare also H. S.Harned in “ A Treatise on Physical Chemistry,” edited by H. S. Taylor(Macmillan, 1924), p. 701.2 H. S. Harned, J . Amer. Chem. SOC., 1925, 47, 676; A., ii, 397.3 Idem, ibid., p.684; A., ii, 398.4 Idem, ibid., p. 689; A., ii, 398.6 Idem, ibid., p. 930; A., ii, 538.6 H. S. Harned and R. D. Sturgis, ibid., p. 945; A., ii, 538.7 H. S. Harned and M. H. Fleysher, ibid., p. 82; A., ii, 538.has been almost universally adopted.Many of theresults in refs. 2 to 7 are collected in a summarising paper by H. S. Harned,2. physikal. Chem., 1925, 11’7, 1 ; A., ii, 977.8 G. Nonhebel and H. Hartley, Phil. Mag., 1925, [vi], 50, 729; A., ii, 1061.9 W. W. Lucasse, J . Amer. Chem. SOC., 1925, 47, 743; A., ii, 399.10 J. N. Pearce and R. W. Gelbach, J . Physical Chem., 1925, 29, 1023;11 J. D. C. Anthony and L. J. Hudleston, J., 1925, 127, 1122.12 J, Amer. Chem. SOC., 1925, 47, 641; A., ii, 397.A., ii, 867GENERAL AND PHYSICAL CHEMISTRY.29ides and potassium hydroxide by the use of a form of the Debyeequation for extrapolation to zero concentration. l3 The activitiesand activity coefficients of a number of salts in aqueous solution(and in some salt solutions) are thus known with considerableaccuracy. The activity coefficients of a number of salts are plottedin Fig. 2 against their concentrations.It will be observed that with increasing concentration the activitycoefficient first diminishes, reaches a minimum, and rises again,FIG. 2.-J1 2Square root of concentration.becoming greater than unity at high concentrations. This behav-iour appears to be general.The first attempt to obtain a general formula for the change ofactivity coefficient with concentration was made by G.N. Lewisand G. A. Linhart,14 who showed that in very dilute solution theobserved values could be represented by an equation of the typelogf = - Pea', where p and a’ are constants. G. N. Lewis andM. Randall l5 suggested the empirical rule that for uni-univalentelectrolytes a’ = 1/2 and J. N. Bronsted 16 employed a similarl3 G. Scatcherd, J. Arner. Chem. Soc., 1925, 47, 648; A., ii, 397.l4 Ibid., 1919, 41, 1951; A., 1920, ii, 97.l6 “ Thermodynamics,” p. 345.l6 J . Amer. Chem. Soc., 1922, 44, 938; A., 1922, ii, 48230 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.relation, while B. A. M. Cavanagh l7 showed that an equation ofthis form followed from S. R. Milner’s theory of electrolytes. Whilstsuch an equation covers the diminution of the activity coefficienta t small concentrations, it is necessary to introduce another termto include the subsequent rise.Thus H. S. Harned18 has giventhe empirical equation logf = - pea' + ccc, where a is a thirdconstant, and has shown that values of the constants can be foundwhich satisfactorily reproduce the observed values over a widerange of concentration. J. N. Bronsted employed the similarequation logf = - 0 . 4 2 ~ ~ ’ ~ + ac for uni-univalent electrolytes.19The activity coefficient of an electrolyte at fixed concentrationin the presence of increasing concentrations of other salts followsa similar course, but the magnitude of the effect varies considerablyaccording to the valence type of the salts. In order to eliminatedifferences of the electric forces in equal concentrations of ions ofdifferent valencies, Lewis and Randall 2o introduced a quantitycalled the ionic strength (p), obtained by multiplying the con-centration of each ion by the square of its valency and dividingthe sum of the products by two.They were then able to statethe general principle that in dilute solutions “ the activity coefficientof a given strong electrolyte is the same in all solutions of the sameionic strength.” In stronger solutions, deviations appear owingto the individual behaviour of ions.Turning now to the attempts to explain the behaviour of strongelectrolytes in terms of interionic electric forces, the Debye-Huckeltheory 2 l has been greatly extended.22a P. Debye has given a moredirect derivation of his fundamental equation of the relationbetween activity coefficient and concentration.22b The first step1 7 Phil.Mag., 1922, [vi], 44, 226, 610.18 J . Amer. Chem. SOC., 1920, 42, 1805; 1922, 44, 252; A., 1920, ii, 664;l9 LOC. cit., ref. 16.20 J . Amer. Chem. Soc., 1921, 43, 1112; A., 1921, ii, 427.2 1 Ann. Report, 1924, p. 25.22 Bibliography below :-1922, ii, 255.(a) I?. Debye and E. Huckel, “ On the Theory of Electrolytes.”I. The freezing point lowering and reIated phenomena, Physikal. Z.,1923, 24, 185; A., 1923, ii, 459. 11. The limiting law of electrical con-ductivity, ibid., 1923, 24, 305; A., 1923, ii, 724. (b) P. Debye, “ TheOsmotic Equation of State and Activity of Dilute Strong Electrolytes,”ibid., 1924, 25, 97; A., 1924, ii, 386.(c) 0. Scharer, “The Theory ofSolubility Influences in Strong Electrolytes,” ibid., 1924, 25, 145; A.,1924, ii, 455. (d) I?. Gross and 0. Halpern, “ On the Dilution Law andDistribution of Strong Electrolytes,” ibid., 1924, 25, 393; A., 1925,ii, 117. (e) A. Frivold, “Contribution to Knowledge of So-calledAnomalous Properties of Strong Electrolytes,” ibid., 1924, 25, 465 ; A.,1925, ii, 396. df) P. Debye and J. McAulny, “The Electric Field oGENERAL AND PHYSICAL CHEMISTRY. 31is the calculation of the electrical potential of an ion in the solutiondue to all the other ions about it, which is effected by the combineduse of Boltzmann’s equation and Coulomb’s law. To a firstapproximation (neglecting the dimensions of the ion itself) it hasthe value I) = - eF,/D, where ei is the charge on the ion, D thedielectric constant of the medium, and K a quantity characteristic4x 8xe2 Nof the solution which is given by K~ = = B ~ P , DETin which ni is the number of ions of the ith kind per C.C.in the solu-tion, E the charge on a univalent ion, N the Avogadro number,E the gas constant per molecule, and p the ionic strength. Insteadof calculating the total electrical energy as before,22a Debye nowdeduces the work, W , which must be done in giving the ions theircharge, assuming them to be initially uncharged; W = X~niei$i/3for all the ions in one C.C.The free energy of the system is greater by this amount than ifthere were no electric forces between the ions, i.e., CAP =ENiET log ci/ciO + W ; * actually ZAF = ZN&T logfici/c,O, whenceit is only a matter of mathematics to deduce the result,for a salt giving vi ions of valency 2%.For an electrolyte giving ionsof valencies xlzz this reduces to loglOf = zlz,BY/Land at 0” B = 0.5.It must be clearly understood that these equations represent* For brevity, summation is taken to include the solvent and all the kindsof ions present.~~ ~~~~~~~Ions and Neutral-salt Action,” ibid., 1925, 26, 22; A., ii, 171. ( 9 ) E.Huckel, “ On the Theory of Concentrated Aqueous Solutions of StrongElectrolytes,” ibid., 1925, 26, 93; A., ii, 513. (h) 0. Redlich, “ On theTheory of Electrolytic Conductivity,” ibid., 1925, 26, 199; A., ii, 541.( i ) P. Gross and 0.Halpern, “ On the Temperature-dependent Para-meter in Statistics and the Debye Theory of Electrolytes, ibid., 1925,26, 403; A., ii, 566. ( j ) A. A. Noyes, “ Interionic Attraction Theoryof Ionised Solutes.” I. “ Critical Presentation of the Theory,” J . Amer.Chem. SOC., 1924, 46, 1080; A., 1924, ii, 658. 11. “ Testing the Theorywith Experimental Data,” ibid., p. 1098; A., 1924, ii, 659. (k) A. A.Noyes and W. P. Baxter, 111. “ Testing the Theory in Alcohol Solvents,”ibid., 1925, 47,2122; A., ii, 970. ( I ) P. Debye and L. Pauling, IV. “ TheInfluence of Variation of Dielectric Constant on the Limiting Law,” ibid.,p. 2129; A., ii, 970. (m) P. Gross and 0. Halpern, “Electrolytes inSolutions of Low Dielectric Constant,” Physikal. Z . , 1925, 26, 636; A.,ii, 1152.(n.) Compare also J. J. van Laar, ‘‘ On the Theory of StrongElectrolytes and its History,” 2. anorg. Chem., 1924,139, 10832 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the “ limiting law ” a t very small concentrations; in most casesconsiderable deviations occur below 0.W. A. A. Noyes z z j dis-cussed a large body of data and came to the conclusion that althoughdeviations begin a t quite small concentrations, the evidence sup-ported the truth of the equation in limiting cases. J. N. Bronstedand V. K. LaMer 23 have since determined the activity coefficientsof a number of complex cobaltammines of various valence typesin dilute salt solutions up to 0*02N, and find that they are com-pletely in accordance with the Debye equations.F. Hovorka andW. H. Rodebush 24 have determined the freezing points of solutionsof seven electrolytes between 0.01 and 0*001M, ‘‘ which show ratherremarkable agreement with the values derived from the formulaof Debye and Huckel.”On the other hand, M. Randall and A. P. Vanselow 25 find thatthe freezing points of solutions of hydrogen chloride, thallouschloride, and lead nitrate are not in good agreement. G. Scatchard,26however, claims that they are in agreement with the modifiedequation discussed below.The first step in the extension of the theory to more concentratedsolutions is to take account of the size of the ions. If the ion hasfinite size, the expression for the potential becomesz.$ K+i = - -- - D 1 +- Kas’where ai is the mean least distance of approach of the ccntre ofany ion to that of the ion in question.The activity coefficientequations becomeandassuming that the mean ionic radius has a mean value, a, for allions.It has been shown by Scatchard26 that this is equivalent to theempirical equation logf = - pc1I2 + CLC, and p = 0.5 for uni-univalentsalts. 0. Scharer has applied equation (4) to the solubilities of saltsin salt solutions.22c The ionic radius term a is unknown and is ailadjustable variable in the equation. He finds the values whichreproduce the experimental data best by a graphical method, andthus obtains equations which completely represent the solubilities23 J . Amer. Chem. SOC., 1924, 46, 555; A., 1924, ii, 30624 Ibid., 1925, 47, 1614; A., ii, 772.z 5 Ibid., 1924, 443, 2418; A , , 1925, ii, 33. 26 LOC.cit., ref. 12GENERAL AND PHYSICAL CHEMISTRY. 33of calcium sulphate, silver sulphate, thallous chloride, and variouscobaltammine salts in salt solutions, with and without a common ion.A. A. Noyes 27 pointed out that there is an irreconcilable differencebetween the results of the Debye and the Milner 28 calculations ofthe inter-ionic energy. The two theories have been further criticallycompared by S. R. Pike and G. N ~ n h e b e l , ~ ~ who come to the con-clusion that neither can do more than indicate the form of theequation. G. Nonhebel and H. Hartleym have examined theactivity coefficients of hydrogen chloride in methyl alcohol, ethylalcohol, and water with the same object.Whereas the Debyecalculation leads to the expression - logf = pdc- CYC, theMilner equation becomes - logf = I.OlSpf(c)d< where f(c) is atabulated function of the concentration. These authors concludethat the Milner equation without any adjustable constant cc repre-sents the data better than the Debye formula with one, and findthat the activity coefficients are well represented by empiricalequations of the form - logf = p’dc and that the values of P’/aare in good agreement with the Milner function f(c) at 000005n.Further work on this discrepancy will be welcome.R. H. Fowler 31 has examined the range of validity of the com-bined use of Boltzmann’s and Poisson’s equations with particularreference to the Debye-Hiickel theory and concludes that thevalidity of this theory cannot be regarded as established except forsmall values of the ionic concentrations.The Debye equation has been tested on another point (in whichit agrees with the Milner equation).The fundamental equationindicates that at the same concentration in different solventslog f K 1 /D3I2. This requirement has been confirmed by A. A. Noyesand W. P. Baxter,32 using the data for lithium chloride, hydrogencKloride, and sodium ethoxide in ethyl alcohol, and by G. Nonhebeland H. H a r t l e ~ . ~ ~It will be observed that equations (1)-(4), in which logf is neces-sarily negative, cannot account for the rise of the activity coefficientabove unity in concentrated solutions. I n order to explain this,Hucke122g has considered the change of dielectric constant of thesolution with concentration.It is assumed that the addition of2 7 LOC. cit., ref. 22, j , I .28 Phil. Mag., 1912, [vi], 23, 551; 1913, 25, 742; 1918, 35, 214, 362; A . ,1913,ii, 481; 1918, ii, 54, 148; Trans. Faraday Soc., 1919,15, 148; A . , 1920,ii, 152.2s Phil. Mag., 1925, [vi], 50, 723 ; A , , ii, 1061.31 Proc. Camb. Phil. SOC., 1925, 22, 861.32 LOC. cit., ref. 22, k.33 LOG. cit., ref. 8.47, 2098 ; A., ii, 971.30 LOC. cit., ref. 8.Compare also G. Scatchard, J . Amer. Chein. Soc., 1925,REP.-VOL. XXII. 34 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.salts causes a lowering of the D.C. by an amount proportional tothe concentration, as expressed by the formula D = Do - XSc,where 6 is the lowering produced by unit concentration of oneparticular kind of ion.A change of D.C. involves, in addition toits effect on the Coulomb law expression, a change in the electricalenergy of the ions themselves in the medium. If it be supposedthat the charge ed is located on a sphere of radius bi, the potentialat the surface is ei/Dbi and the corresponding electrical energyei2/2Dbi. I n bringing the ions from an infinitely dilute solution(D.C. = Do) to a solution of D.C. = D, the electrical energy willincrease byand this term must be added to the Coulomb expression in orderto obtain the complete electrical work term. In order to simplifythe calculation, Hiickel puts ai = bi and uses a mean value, a, forall the ions present, thus obtaining the result :wheref(K) is a complicated function of K which is found on cal-culation to be nearly proportional to the concentration.Hencefor a uni-univalent saltwhere A and B have the same values as before and C is a thirdconstant. Values of C corresponding to various values of 6 arecalculated and that value which fits the observed data best isselected. The activity coefficients of lithium, sodium, and potass-ium chlorides over the whole range of concentration are givenby the equation, assuming the values of the D.C. lowering coefficient,6, to be 20, 9, and 6, respectively. Equally good agreement withthe observed results for hydrogen chloride was obtained both onthe assumption that the hydrogen ion is free (H+) and that it existsas the hydrate (H30+), different values of the constants beingrequired for the two cases.It would appear that a considerable step forward in our knowledgeof the factors determining the behaviour of salt solutions has beenmade.It must be remembered, however, that in the final equationthere are two variable factors which can be selected to fit theobserved results. The outcome is not, therefore, a calculation ofactivities from fundamental data, and until the constants havebeen obtained independently the theory must be regarded as GENERAL AND PHYSICAL CHEMISTRY. 35derivation of the form of the empirical equation, taking accountof inter-ionic forces and the dielectric constant.The somewhat artificial character of the calculation is realisedby Debye and Hiickel, and the latter has given an exhaustive dis-cussion of the factors concerned in concentrated aqueous solutions.34The high dielectric constant of water means high polarisability inan electric field and the presence of molecules which act as electric“ dipoles.” I n the intense electric fields in the vicinity of ions thedipoles must be oriented and owing to the intensity of the forces 35it is probable that ‘‘ electric saturation,” i.e., total possible orien-tation, occurs. Each ion is therefore surrounded by an atmosphereof water “ bound ” by electrostatic forces.An applied electricfield must have a smaller effect on solvent molecules in the vicinityof ions than on the unoriented solvent, hence the dielectric constantis lowered by the presence of ions.This view was originally putforward by K. Fajans,36 and M. Born 37 has shown that the hydrationenergy of ions can be accounted for on the same basis.The salting-out effect of non-electrolytes by salts has beendiscussed by P. Debye and J. McAulay 225 from the same point ofview. The effect of introducing a strong electrolyte into a solutionof a non-electrolyte, according to these authors, is to cause themore polarisable components to amass themselves round the ions,where the electric field is great. If the solvent has the greaterpolarisation capacity, the effect is a displacement of the non-electrolyte from the vicinity of the ion (ie., an apparent diminutionof the solution volume) and a rise in its activity. If the non-electrolyte is more polarisable than the solvent and raises its D.C.,the effect is the reverse.Calculations of the increase of the activityof non-electrolytes by salts on these lines agree with the magnitudeof the effect.38 The importance of these theories on the questionof hydration in solution is obvious, but it is felt that the time isscarcely ripe for a general discussion.P. Gross and 0. Halpern have further considered22m the behaviourof electrolytes in solvents of low dielectric constant. They findthat the effect of the ionic charges on the osmotic properties maybe not only small, but also in the reverse direction of the Coulombeffect described above. The solute will thus appear to be associ-34 LOG. cit., ref. 22, g.35 At 3 x 10-8 cm., Hiickel estimates the potential gradient at 2 X lo636 Ber.Deut. Physikal. Ges., 1919, 21, 549, 709; A., 1920, ii, 12, 154.volts per cm.. 3 7 2. Physilc, 1920, 1, 45; A., 1921, ii, 166. Compare also 0. Bliih,ibid., 1924, 25, 220; A., 1924, ii, 824; Naturwiss., 1921, p. 732.38 Compare also E. A. Hafner and L. von Kiirthy, Arch. exp. Path. €’harm.,1924, 104, 148; A., 1925, ii, 283.B 36 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.ated. They are able to account qualitatively for the various typesof anomalous behaviour observed in non-aqueous solutions.The determination of the dielectric constants of solutions ofelectrolytes has thus become a matter of considerable importance.Until recently no direct means of measurement was available, butthe difficulty has been overcome by the use of electric oscillationsof short ~ a v e - l e n g t h .~ ~ The lowering of the D.C. of water by saltsis confirmed. I n the case of electrolytes such as tetrapropyl-ammonium iodide in alcoholic solvents, the initial decrease isfollowed by a rise.Conductivity of Strong Electrolytes.On the theory of complete dissociation the change of the equivalentconductivity of a strong electrolyte with dilution is ascribed tochanges in the inter-ionic forces. The theory of J. C. Ghosh did notsurvive P. Debye and E. Hiickel41 have treated theconductivity problem on the same basis as their theory of osmoticproperties. It was there postulated that every ion is immediatelysurrounded by an excess of ions of opposite charge.When theion is in motion through the solution, a finite time is required forthe redistribution of ions in this fashion (period of relaxation)and there will always be an excess of ions of opposite sign in itsrear, hence it will be subject to a retarding force. Further, sinceions of opposite sign are moving in different directions and dragwith them a certain amount of solvent, the viscous resistance t othe motion of an ion will be greater than if the other ions were atrest. Assuming Stokes’s law, Debye and Hiickel have computedthese effects and deduced the relation for dilute solutions :A0 - + K,b)d%,where A, and A, are the equivalent conductivities at infinite dilutionand at concentration c, wl = 1/2(1a/lc + &/la), la and Zc being themobilities of anion and kation, b the mean ionic radius, Kl and Kzconstants depending on the temperature and D.C.of the medium.The first term in the bracket represents the period of relaxationeffect, the second the viscosity effect. This equation agrees withthe empirical relation found by Kohlrausch 42 for the conductivityof dilute salt solutions, A. - A, = x l / c : Using a modified form of39 R. T. Lattey, Phil. Mag., 1921, [vi], 41, 829; A., 1921, ii, 426; K.Theodortschick, Physikal. Z., 1922, 23, 344; P. Walden, H. Ulich, and 0.Werner, 2. physikal. Chew., 1924, 110, 43; 1925, 115, 117; 1925, 116, 261;A., ii, 512, 773.40 Ann. Report, 1918, 11; 1919, 14.4l LOG. cit., ref. 22, a, 11.42 2. Elektrochem., 1907, 13, 333; A,, 1907, ii, 600GENERAL AND PHYSICAL CHEMISTRY.37Stokes’s law, 0. Redlich has obtained a modified equation whichgives exact agreement with the experimental results for aqueoussolutions. J. E. Frazer and H. Hartleya have determined theconductivities of fifteen univalent salts in methyl alcohol and findthat although they agree with the form of the equation, they arenot consistent with the value of w given above, indicating thatsome revision of the theory is necessary in this respect. C. W.Davies 45 also has given an empirical equation which is in goodagreement with the data of aqueous solutions, viz. : A, - & =Kdz(dc + dz). According to Frazer and Hartley, this is notapplicable to methyl-alcoholic solutions. A. Ferguson and I. Voge146have used an empirical equation of the form : A, - A, = Ben.Activities in Binary Liquid Mixtures and Deviations fromRaoult’s Law.Activities in binary liquid mixtures of non-electrolytes have alsoreceived much attention in recent years.The most general expres-sion of Raoult’s law of perfect solutions is that the activity of acomponent (taken as unity for the pure liquid) is equal to the mo1.-fraction. The deviations from Raoult’s law which occur in manysystems have been widely discussed in the past and have beenattributed exclusively to chemical and to physical effects. Theattempt to explain all deviations chemically (e.g., by solvation andassociation) failed, although they certainly occur in some systems.Attention has therefore been focussed on purely physical effects.A comprehensive theory of liquid mixtures has been developed byJ. H.Hildebrand and collab0rators.~7 In a perfect solution amolecule of any,component behaves exactly as if in its own pureliquid, and any deviation from ideality must be due to the differencebetween the forces acting on a given molecule in the solution andwhen it is surrounded solely by molecules of its own kind (Le., inthe pure liquid component). Deviations will obviously be leastwith liquids of very similar nature in which the intermolecular forcesare nearly identical. As a measure of the forces between moleculesin different liquids Hildebrand has taken the internal pressure.He has obtained concordant values of this quantity from a varietyof properties, the constants of van der Waals’s equation, surface43 LOG.cit., ref. 22, h.44 Proc. Roy. SOC., 1925, A , 109, 351; A., ii, 1163.45 J . Physical Chem., 1925, 29, 473, 973, 977; A., ii, 541, 871.46 Phil. Mag., 1925, [vi], 50, 971; A., ii, 1163.4 7 J . Amer. Chem. SOC., 1916, 38, 1452; 1017, 39, 2297; 1919, 41, 1067;1920, 42, 2180, 2213; 1921, 43, 500, 2172; 1923, 45, 682, 2828; A., 1916,ii, 518; 1918, ii, 36, 65; 1919, ii, 392; 1921, ii, 23, 24, 307; 1922, ii, 141;1923, ii, 315; 1924, ii, 94; J. H. Hildebrand, “Solubility” (Chem. Cat. Coy).,192438 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.tension, heat of vaporisation, and from solubility data, and hasshown that deviations from Raoult’s law are qualitatively pro-portional to the internal pressure difference of the components.This theory has been extended to solubility relations by theconsideration of the solubility curve up to the melting point of thesolute, at which the solubility expressed as mo1.-fraction in theliquid phase is unity. The “ ideal ” solubility curve for solutionswhich obey Raoult’s law is given by the relation : d log N/d( 1 /T) =- Lf/4-58, where N is the mo1.-fraction of solute, and Lf the latentheat of fusion of solute.Hence, if log N is plotted against 1/T, astraight line is obtained for an ideal solution having the slope- Lf14.68. When the solubility curves of a given solute in anumber of solvents are plotted in this way a family of curves isobtained deviating more or less from the ideal line.Such sets ofcurves have been obtained for na~hthalene,~8 iodine,4* s~lphur,~gand a number of organic compounds.50 The ratio of the actualslope of the solubility curve t o the ideal slope (a factor f ) has beenshown by F. S. Mortimer 50 to be related to the internal pressuresof the solvent and solute by the equation f = Kl - Kz + 1, whereKl and Kz are the relative internal pressures, referred to naphtha-lene as unity. He has described a chart by which the properfactor can be read off for any pair of substances the relative internalpressures of which are known. It is thus possible to predict themutual solubilities of many non-polar or slightly polar substanceswith some precision.Whilst Hildebrand’s theory gives a qualitative indication ofdeviations from Raoult’s law over a wide field, it has not beendeveloped quantitatively.J. A. V. Butler 51 considers that thepartial heat of solution is a better measure of the difference betweenthe forces acting on the molecules of a component in solution andin their pure liquids, and shows that in the case of thallium amal-gams,52 the logarithm of the activity coefficient, which representsthe deviation from Raoult’s law, is almost exactly proportional tothe partial heat of solution. Close proportionality is also shownby the less accurate data of a number of binary alloys.534 s J. H. Hildebrand and C. A. Jenks, J . Amer. Chenz. XOC., 1920, 42, 2180;49 Idem, ibid., 1921, 43, 2172; A., 1922, ii, 141.60 F. S . Mortimer, ibid., 1922, 44, 1416; 1923, 45, 633; A ., 1922, ii, 621;61 Ibid., 1925, 47, 117; A., ii, 539.62 T. W. Richards and F. Daniels, ibid., 1919, 41, 1732 ; G. N. Lewis and53 N. W. Taylor, ibid., 1923, 45, 2865; A., 1924, ii, 80.A . , 1921, ii, 23.1923, ii, 299.M. Randall, ibid., 1921, 43, 233; A., 1920, ii, 34; 1921, ii, 241GENERAL AND PHYSICAL CHEMISTRY. 39The Galvanic Cell and Potential DiSferences.The seat of the electromotive force in the galvanic cell has beendiscussed afresh by J. A. V. Butler.54 The establishment of theGibbs-Helmholtz relation between the electrical energy producedand the total energy of the reaction going on in the cell, and thewide use of the Nernst relation between the electrode potential andconcentration of metal ions caused attention to be focussed almostexclusively on the chemical effects a t the electrodes as the principalsources of the electromotive force.Recent physical investigations 55on the thermionic and photoelectric properties of metals have,however, demonstrated conclusively the existence of large metalcontact P.D.'s. The question arises, How are these to be reconciledwith the " chemical '' theory and in particular with the correspond-ence between the electromotive force and the energy of the chemicalreaction ? Butler meets this by showing that the energy of transferof electrons from one metal to another, on which the metal contactP.D. depends, is an integral part of the energy of the chemicalreaction. Thus the reaction Zn + Cu" = Cu + Zn" which occursin the Daniel1 cell consists of three parts : (1) the passage of zincions from the metal into the solution, (2) the deposition of copperions on the copper, and (3) the transfer of electrons from themetallic zinc to copper. It is shown that the energy change of thethird part is large, in fact of the same order of magnitude as thetotal energy of the reaction.In the galvanic cell the three stagesoccur at the two electrodes and a t the metal junction, and eachgives rise to its appropriate P.D. It thus appears that the twoconflicting theories of the galvanic cell, the " chemical '' and the" physical," are finally reconciled.It is further pointed out that the existence of large metal contactP.D.'s has an important bearing on the determination of theabsolute electrode potentials.The possibility of a metal junctionP.D. between the metal investigated and the reference electrodehas been overlooked, and it is likely that the discordant resultsobtained in methods employing mercury and those using othermetals is due to this cause.J. A. V. Butler has further given a kinetic theory of the P.D. atmetal electrodes (Nernst P.D.),56 a t oxidation electrode^,^' and at64 Phil. Mag., 1924, [vi], 48, 927; A., 1925, ii, 42.6 5 0. W. Richardson and K. T. Compton, ibid., 1912, [vi], 24, 592; A.,1912, ii, 1039; R. A. Millikan, Physical Rev., 1916, 7, 18; 1921, 18, 236;A. E. Hennings and W. H. Kadesch, ibid., 1916, 8, 209.66 Trans. Paraday SOC., 1924, 19, 720; A., 1924, ii, 598; compare Ann.Report, 1924, p.17.Trans. Paraday Xoc., 1924, 19, 734; A . , 1924, ii, 59840 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.metal junctions.58 The expression obtained for the electrodepotential of a metal is :U RT RTnF nP nF E = + __ logK + -- log C,in which U is the total energy change of the transfer of metal ionsfrom the metal to the solution and K is a small constant charac-teristic of the metal. The first two terms are equivalent to theNernst “ solution pressure.” By means of a cyclic process,SB it hasbeen shown thatU = X+ J - H - +F,where X is the latent heat of vaporisation of the metal, J is theenergy required to ionise it in the vapour state, H is the hydrationenergy of metal ions, and - +F the heat evolved in returning theelectrons to the metal (4 = thermionic work function).J. Heyrovskf 6o also has discussed the factors determining theNernst potential and by means of a thermodynamical argumenthas oht,nined a somewhat similar expression :H RT log P - + __ log c,RT= - P H Fin which P includes quantities which depend on the metal aloneand is regarded as the real “ solution pressure.’’ However, it maybe noted that the electrode potentials calculated by this expressiondiffer from the observed much more widely than those obtained byassuming that the electrical energy is simply equivalent to the totalenergy of the cell, and it is concluded from a similar argument thatthe metal contact P.D. is small (not greater than 0.2 volt), whichis contrary to a large body of experimental evidence.J. Heyrovsky 61 and collaborators have published an extensiveseries of researches on electrolysis with the dropping mercurycathode. An instrument called the polarograph is described 62which automatically records decomposition curves. It is claimedthat the dropping mercury cathode has a number of advantagesover electrodes hitherto employed. A fresh surface is continuallyexposed, reversible polarisation curves are obtained with veryminute currents and the hydrogen overvoltage is the highest whichhas been observed. A variety of problems has been investigated5 8 Phil. Mag., 1924, [vi], 48, 746.59 Loc. cit., ref. 54.60 J . Physical Chem., 1925, 29, 344, 406; A., ii, 404, 544; Rec. trm. chim.,61 Trans. Paraday Soc., 1924, 19, 692; A., 1924, ii, 598; RPC. truv. chim.,62 J . Heyrovsk$ and M. Shilrata, ibid., p. 496,1925, 46, 447; A., ii, 672; Compt. rend., 1925, 180, 1653; A . , ii, 793.1935, 44, 488-606; A., ii, 673-678GENERAL AND PHYSICAL CHEMISTRY. 41by its use. Its value has been strikingly shown by its independentindication of dvi-manganese in manganese salts. 63Two important papers on the Donnan membrane equilibriumhave appeared. The data of F. G . Donnan and A. J. Allmand 64on the distribution of potassium chloride between a pure aqueoussolution and a solution containing potassium ferrocyanide separatedby a membrane impermeable to the ferrocyanide ion, have beenrecalculated in terms of activities instead of concentrations byN. Kameyama.65 The distribution equilibrium found is in accord-ance with the ionic strength principle. R. Azuma and N. Kame-yama 66 have investigated the potential difference and equilibriumof sodium chloride and Congo-red across a semipermeable collodionmembrane. Assuming that Congo-red ionises as a uni-univalentelectrolyte and the ionic strength principle holds, the equilibriumresults are in agreement with the theory. It was not possible toprove that the P.D. was in agreement with the theoretical value,owing to the difficulty of eliminating liquid-liquid potentials.The theory of membrane equilibria has been restated by E. HiickelY6'in relation to the Debye-Hiickel theory.In conclusion, the Reporter desires to thank Mr. J. A. V. Butlerfor the great help he has given in the preparation of this Report.J. E. COATES.63 V. DolejEiek and J. Heyrovskfr, Nature, 1925, 116, 782; A. N. Campbell,64 J . , 1914, 105, 1941.66 Phil. Mag., 1925, [vi], 50, 849; A., ii, 1062.66 Ibid., p. 1264.6 7 Kolloid-2. (Zsigmondy Festschrift), 1925, 36, 204 ; A., ii, 528.ibid., p. 866; J. Heyrovskf, ibid., 1926, 117, 16

ISSN:0365-6217    

DOI:10.1039/AR9252200011

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

INORGANIC CHEMISTRY.IN the preparation of the Report for 1925 the task of selection hasproved as difficult as ever, and it is necessary again to draw attentionto the fact that many researches of interest and importance areomitted, or dismissed with a mere mention, often because theirsignificance can only be appreciated on careful study, whereas thisReport is written primarily for those who lack time for such study.Perhaps the most marked general tendency is seen in the increas-ing application of physical methods and criteria to chemical prob-lems, whereby it happens that much matter that could properly beincluded in this Report belongs as much to the preceding Reportand may there be found. Those of us who have always regrettedthe artificial, although apparently convenient, line drawn betweenchemistry and physics welcome the incursions of physicists intochemistry and of chemists into physics which now so frequentlyoccur.Subjects which appear to the Reporter to be of rather specialinterest are : the formation of compounds of helium; the long-delayed confirmation of the production of helium in discharge tubesdescribed by Collie and Patterson ; the reported production of goldby electrical discharges in mercury vapour; the production of anew peroxide of barium; the evidence that the atomic weight ofboron may vary with its source; the proof that carbon can bemelted and the determination of its melting and boiling points;the isolation of pure tin hydride, a new oxide and persulphide ofnitrogen, nitronium perchlorates, bromoazoimide, and the pseudo-halogen radicals oxycyanogen and selenocyanogen ; the proof of theexistence of sulphur sesquioxide ; and the detection of two hithertounknown elements of the manganese group. These matters, andmany others which chemists may find of equal or greater interest,are dealt with, all too briefly, in their appropriate order.Atomic Weights.Hydrogen, Lithium, Carbon.-Using a new modification of themass-spectrograph and the bracketing method of observation, withhelium = 4.000 as standard, the values H = 1.0079 and C = 12.000have been found.By the same method, it has been found that ifN = 14.008, the lithium isotopes have the atomic weights Lis =6.009 and Li7 = 7 012.11 J. L. Costa, Compt.rend., 1925, 180, 1661 ; Ann. Physique, 1925, [XI, 4,25; A., ii, 619, 1021INORGANIC CHEMISTRY. 43Boron.-Determinations of the ratio BCl, : 3Ag by nephelometrictitration with weighed silver in the usual manner, using borontrichloride prepared from boron minerals of known and widelyseparated origin, have given evidence of a variation in the atomicweight of boron. Boron from California gave B = 10.840, whilstsamples from Tuscany and Asia Minor gave B = 10.825 andB = 10.818, respectively : these results indicate that the Cali-fornian boron contains about 2% more of the isotope Bll than dothe other samples.2 Should the observation be confirmed, we havehere the first known case of a natural variation in the atomic weightof one of the lighter elements and it will become of interest to inquirewhether this variation existed originally or has resulted from apartial separation of isotopes occurring in nature through thepeculiar mode of formation of boron minerals by volatilisation ofboron compounds.The mean result now obtained is in agreement with those pre-viously r e p ~ r t e d , ~ but differs considerably from the mean of earlierdata, which were largely based on analyses of borax : it is thereforeof interest that a critical examination of the titration of borax glasswith hydrochloric acid standardised against silver has shown thatborax loses soda on fusion, that the glass is indefinite in composition,and that values of the atomic weight based on the use of thismaterial are .untrustworthy .4Carbon, Nitrogen.-An extension of earlier work on the densitiesand compressibilities of ethylene, nitrous oxide, and nitric oxidehas given the values : C = 12.000 and N = 14.003; N = 140006.~Alum inium.-Using pure a,luminium chloride prepared by theaction of chlorine on alumina and carbon a t a red heat, five deter-minations of the ratio AlC1, : 3Ag and two of the ratio AlCl, : 3AgC1gave in mean A1 = 26~971.~XiZicon.-Silicon tetrachloride, purified by repeated distillationin a high vacuum until it gave a constant vapour pressure, wasdecomposed by sodium hydroxide solution and used to determinethe ratio SiCl, : 4Ag.Four analyses gave in mean Si = 28.105 & 0-003 (mean devi-ation), confirming Baxter's value (28.063) as against that (28-3)formerly accepted.' An attempt has been made t o test the con-H.V. A. Briscoe and P. L. Robinson, J., 1925, 127, 696.Ann. Reports, 1922, 19, 34.H. V. A. Briscoe, P. L. Robinson, and G. E. Stephenson, J., 1925, 127,T. Batuecas, J. Chirn. phys., 1925, 22, 101; A., ii, 497.H. IGepelka and N. Nikolib, Chem. LiSty, 1925, 19, 158; A , , ii, 620.150.' 0. Honigschmid and M. Steinheil, 2. anorg. Chem., 1924, 141, 101;A., 1925, ii, 174.B* 44 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.stancy of the atomic weight of silicon from various sources, terrestrialand meteoritic : comparison of the densities of carefully purifiedsamples of tetraethylsilicane prepared from these sources disclosedno difference greater than that corresponding to a va,riation ofabout 0.02 in the atomic weight : the fact that the variations inrefractive index of the samples showed a general parallelism with thevariations in density was held to indicate that the observed densityvariations were, a t least in part, due to varying proportions ofimpurities and hence that the real variation in the atomic weightof silicon is less than 0-02.8Chlorine.-Redeterminations of the density and compressi-bility of methyl chloride yield for chlorine the value Cl = 3E~47.~Approximate evidence has been obtained for the constancy of theisotope ratio for chlorine, as no difference could be detected in theproportions of chlorine present in silver chloride prepared (a) fromvolcanic ammonium chloride from Vesuvius, ( b ) from water at adepth of 1573 m.in the Calumet and Hecla mines near Lake Superior,and ( c ) from ordinary barium chloride; lo and the atomic weightof chlorine from " shale balls " associated with the Canyon Diabolometeorite (although this chlorine is doubtfully of meteoritic origin)was found not to differ from that of " ordinary " chlorine by morethan 1 part in 2000 parts.llCopper.-The rejection by the German Commission on AtomicWeights of the value reported last year l2 has led to a series ofexperiments which shows that homogeneous cupric oxide, freefrom occluded gases, is in fact obtained by heating the oxide firstat 1000" in air and then in oxygen and finally for a long period a tabout 700" in oxygen. Hence the value Cu = 63-546 is reaffirmed.138eZenium.-Hydrogen selenide was prepared from carefullypurified selenium, either by direct union with hydrogen a t 700"or by the action of water on aluminium selenide, and purified bycondensation a t - 80".As a mean of 53 determinations by directweighing, the normal litre of hydrogen selenide weighs 3.6624 grams,whence the atomic weight of selenium is Se = 79*23.14Bromine.-Ammonium bromide was subjected to a prolongedsystematic fractional crystallisation involving about 2700 crystal-* F. M. Jaeger and D. W. Dijkstra, Proc. K . Akad. Wetensch. Amsterdam,9 T . Batuecas, Compt. rend., 1925, 180, 1929; 181, 40; A., ii, 753.1924, 2'7, 393; A., 1925, ii, 83.10 (Mlle.) E . Gleditsch, J . Chim. phys., 1924, 21, 456; A., 1926, ii, 174.11 A.W. C . Menzies, Nature, 1925, 116, 643; A., ii, 1109.12 Ann. Reports, 1924, 21, 28.13 R. Ruer and I<. Bode, Ber., 1925, 58, [B], 852; A., ii, 620.14 P. Bruylants, F. Lafortune, and L. Verbruggen, BUZZ. SOC. chim. Belg.,1924, 33, 687; A,, 1925, ii, 174INORGANIC CHEMISTRY. 45lisations and the bromine in the final head and tail fractions wasrigorously purified by chemical means, re-converted into ammoniumbromide, and used for gravimetric determinations of the ratioAg : AgBr, employing a special apparatus and technique obviatingtransference of the silver bromide during the operations of pre-cipitation, filtration, and weighing. Identical values were obtainedfor both end fractions, showing that fractionation had producedno change as great as 1% in the isotope-ratio, and the general meanvalue Br = 79.914 5 0.003 differs by less than 1 part in 50,000parts from Baxter's previous value, and confirms the acceptedfigure.l5Zirconium-Samples of zirconium material used for a'tomicweight determinations by Venable and Bell l6 have been found tocontain from 0.7% to l.Oyo of hafnium : a correction being appliedfor this impurity, the atomic weight of zirconium is Zr == 91.30-1.l' This figure is confirmed by determinations of thebromide : silver ratio, similarly corrected for traces of hafniumpresent, yielding the value Zr = 9 1 ~ 2 2 . ~ ~Holmium.-Material purified by fractionation as bromate andby partial decomposition of the nitrate and shown to be free fromyttrium and dysprosium by measurements of magnetic susceptibilitywas used for determinations of the ratio HoCl, : 3Ag, giving thevalue Ho = 163.47.19Hafnizcm.-Specimens of hafnium bromide of relatively highpurity, in one case containing only 0.16% of zirconia, were preparedby igniting hafnia with sugar charcoal in a current of nitrogensaturated with bromine and andyscd in the usual manner. Theresults, corrected for the effect of the small proportion of zirconiumpresent, give for the atomic weight of hafnium, Mf = 178-6 & 0*08.20Lead.-Determinations of the ratio of lead chloride to silver,with samples of lead extracted from pitchblende from the BelgianCongo, have given the values Pb = 206.19 and 206-14.21 Com-parison of the atomic weight of lead from Norwegian cleveite with1 5 P.L. Robinson and H. V. A. Briscoe, J., 1925, 127, 138; compareBaxter, J . Amer. Chern. SOC., 1906, 28, 1322.16 F. P. Venable and J. M. Bell, J . Amer. Chem. Soc., 1917, 39, 1598; A.,1917, ii, 479.I7 G. Hevesy, Nature, 1925, 115, 336; A . , ii, 255.18 0. Honigschmid, E. Zintl, and F. GonzSlez, Anal. 3%. Qudm., 1924,18 F. H. Driggs and B. S. Hopkins, J . Amer. Chem. Soc., 1925, 47, 363;20 0. Honigschmid and E. Zintl, Ber., 1925, 58, [B], 453 ; see also 2. anorg.2 1 13. Brennen, Compt. rend., 1925, 180, 252; Ann. Chim., 1925, [x], 4,22, 432; A., 1925, ii, 174.A., ii, 463.Chem., 1924, 140, 335; A., 1925, ii, 347, 255.127; A., ii, 174, 110946 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.that of ordinary lead (207.18) by determining the ratio PbCI, : PbSO,and by measuring the densities of saturated solutions of the nitrates,has given for the former material the value Pb = 206-17.22Bismuth.-In a repetition, with improved technique, of a methodpreviously reported,23 bismuth triphenyl purified by distillation ina, vacuum was treated with oxalic acid and the resulting oxalatewas ignited to oxide in an apparatus such that these operationsinvolved no transference of material. Fifteen experiments gavein mean the value Bi = 208.989,24 confirming the former determin-ations by the same method and in good agreement with the evidenceafforded by the mass-spectrograph that bismuth is a simple elementof mass number 209.25Group 0.Under certain conditions, in the presence of an electric glow dis-charge, mercury and helium combine to form mercury helide.This substance, the simplest formula for which is HgHe,,, is a com-paratively stable substance, but slightly absorbed in charcoal cooledwith liquid air and decomposed a t a bright red heat.26 Whenhelium is subjected to intense electronic bombardment at lowpressures in contact with a heated tungsten filament, both elementsdisappear with formation of a black deposit which is decomposedby nitric acid or aqueous potassium hydroxide with evolution ofhelium to yield tungstic oxide or a clear solution.I n the absenceof mercury vapour, the atomic ratio of the loss in weight ofthe filament and the loss of helium was 1 : 2 and there is thusstrong evidence for the formation of a stable compound WHe,.From mixtures with the vapours of mercury, iodine, sulphur,and phosphorus subject to electronic bombardment in the vicinityof surfaces cooled with liquid air, helium disappears compar-atively quickly and solid substances are obtained the behaviourof which suggests that they are compounds of helium stable a t- 180" but decomposing a t higher temperat~res.~' When heliumwas ionised by radon in presence of mercury, no evidence of com-pound formation could be obtained; but this is not necessarily a t22 (Mlle.) E.Gleditsch, (Mme.) Dorenfeldt, and 0. TV. Berg, J. Chim. Phys.,23 Ann. Reporte, 1921,18, 36.24 A. Classen and G. Strauch, 2. anorg. Chem., 1924, 141, 82; A., 1925, ii,25 F. W. Aston, Phil. Mag., 1925, [vi], 49, 1191; A., ii, 618.26 J.J. Manley, Nature, 1924, 114, 861; 1925, 115, 337, 947; A., ii, 57,2 7 E. H. Boomer, Proc. Boy. SOC., 1925, A , 109, 198; Nature, 1925, 115,1925, 22, 253; A., ii, 732.176.314, 696.16; A., ii, 925, 144INORGANIC CHEMISTRY. 47variance with the foregoing observations.28 These are of specialinterest in that they may account for numerous failures to repeatthe experiments of Collie and Patterson 29 indicating the productionof helium and neon in discharge tubes. It has now been found thatbombardment of the nitrides of magnesium and aluminium at thefocus of a concave cathode in a tube containing oxygen produceshelium, hydrogen, and neon, that discharge tubes after 60 hours'use, when powdered and heated at 800" in a vacuum, yield con-siderable amounts of helium, and that the rare gases were alwaysobtained in discharge tubes when using an induction coil giving a6-inch spark, but not with a larger c~il.~OBy compressing xenon in presence of water below 24", the criticaltemperature of decomposition, a crystalline hydrate with 6 or 7molecules of water is formed, the dissociation pressures of whichhave been measured over the range to 1.4".Xenon hydrate, witha dissociation pressure of 1-15 atm. a t 0", is much the most stableof the hydrates of the inert ga~es.~1Group I .The work of Coehn and Tramm32 indicated that a mixture ofoxygen and hydrogen dried sufficiently to preclude explosion onheating would, under the action of ultra-violet light, combine asreadily as the undried gases. This work has been very carefullyrepeated using six pairs of quartz tubes filled over mercury with agas mixture produced by electrolysis of an aqueous solution of verypure baryta, one tube of each pair containing pure phosphoric oxide.After drying in the dark for from 2 to 8 weeks, both tubes of eachpair were exposed to the same radiation from a quartz mercury-vapour lamp for several hours and the extent of reaction, as measuredby the rise of mercury in the tubes, was noted.In every case therewas markedly less reaction in the dried tube than in the other, andin those dried for 7 or 8 weeks no measurable contraction occurredin 5 or 6 hours' exposure to radiation. No ozone was produced ineither the wet or the dry gas.33If an electric light bulb is partly immersed in molten sodiumnitrate, and the filament is heated while a potential difference ismaintained between it and a positive electrode in the fused salt,thermionic emission will allow a current up to 0.3 amp.to pass28 S. C. Lind and D. C. Bardwell, Science, 1925, 61, 344; A., ii, 1181.2B J., 1913, 103, 419.30 R. W. Riding and E. C. C. Baly, Proc. Roy. Soc., 1925, A , 109, 186;31 De Forcrand, Compt. rend., 1925, 181, 15; A , , ii, 812.32 Coehn and T r a m , Ber., 1922, 56, 455.33 H. B. Baker and (Miss) M. Cctrlton, J . , 1925, 127, 1990.A., ii, 92548 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.through the glass, and metallic sodium, in amounts up to 0.3 granper hour, is deposited in the bulb.It is stated that sodium lampsgiving a pure sodium spectrum, may thus be prepared.=Recrystallisation from anhydrous ammonia can yield sodium andpotassium cyanides containing less than 0.1% of impurity and, bymeans of a gold-silver thermocouple, pure salts so prepared werefound to have them. p. 563.7" r f 0.3" and 634.5" -& lo, re~pectively.~~An important report has been issued upon the corrosionof copper, brass, and zinc in sea-~vater.~~ Corrosion of copper,whether pure or in brass, occurs by primary formation of cuprouschloride, which, in presence of oxygen, is further oxidised to thebasic chloride Cu,(OH),Cl,,H,O. Zinc corrodes by formation ofcarbonate, hydroxide, and oxychloride, but from brass is prefer-entially removed as chloride (" dezincification ").Miethe and Stammreich have reported that mercury, originallyfree from gold, after prolonged use in a mercury-vapour lamp canbe shown to contain small traces of gold which they believe to havebeen formed by atomic breakdown of Further detailshave now been given of the tests applied to detect gold, dependingprimarily upon separation of the bulk of the mercury by distillation :the residual drop of mercury is dissolved in nitric acid and thegold remaining is estimated by measuring the size of the sphericalcrystal aggregate under the microscope.It is claimed that it isthus possible to detect 1 x mg. of gold in 1 kg. of mercury.3*The atomic weight of gold so obtained has been estimated and foundto be the same as that of ordinary gold,39 although it has been statedthat gold, if obtainable by the transmutation of mercury, shouldhave an atomic weight not less than 198.39a These experimentsreceive confirmation by the independent observation that when acondensed discharge at 600,000 volts is passed between electrodesof mercury and tungsten wire immersed in hydrocarbon oils, theresulting viscous mass of carbon, oil, mercury, etc., can be madeto yield ruby glass and is therefore held to contain gold which wasnot present in the original mercury.40 Under other conditions, bothgold and a complex white metal containing much silver were formed.34 R.C. Burt, J. Opt. SOC. Amer., 1925, 11, 87; A . , ii, 921.35 Grandadam, Compt. rend., 1925, 180, 1598; A., ii, 704.36 G.D. Bengough and R. May, J . Inst. Metals, 1924, 32, 81; A., 1925, ii,3 7 A. Wethe and H. Stammreich, Naturwiss., 1924, 12, 597; Ann. Reports,38 H. Stammrsich, 2. anorg. Chem., 1925, 148, 93; A., ii, 1205.39 0. Honigschmid and E. Zintl, ibid., 1925, 147, 262; A . , ii, 924.39a F. W. Aston, Nnture, 1925, 116, 208; A . , ii, 633.40 H. Nagaoka, Nature, 1925, ll$, 93; J. Phys. Rudizcrn, 1925, [vi], 6,218.1924, 21, 35.209; A . , ii, 835, 1111INORGANIC CHEMISTRY. 49A claim for priority in the transmutation of mercury into otherelements has been made by G a ~ c h l e r , ~ ~ who states that repeatedpassage of momentary high-tension discharges between tungstenelectrodes in a silica tube containing mercury and uranium oxideresults in increased radioactivity due to the production of uranium-X.Group I I .Pure metallic beryllium has been prepared by electrolysis of afused mixture of sodium beryllium fluoride and barium berylliumfluoride.This electrolyte is maintained at 1350° in an Achesongraphite crucible which serves as anode, the cathode being an ironrod, water-cooled internally, to which the beryllium adheres.Chiefly because of the volatility of the fluorides a t the high tem-perature necessary for electrolysis, the yield of metal is low (45--50%), but it is obtained in a compact, crystalline form, dlS" 1.842,containing but traces of sodium or barium and little or no iron :freedom from other metallic impurities is attained if they are excludedfrom the electrolyte.Relatively large quantities of pure berylliaare conveniently prepared for this purpose by a process involvingsolution in aqueous sodium bicarbonate and reprecipitation as basicberyllium carbonate.42 Vapour pressure measurements for hydratedberyllium sulphate indicate that only the tetra- and di-hydrates,and possibly the monohydrate, exist : no evidence could be foundfor the existence of the hexa- and hepta-hydrates described in theliterature .g3Magnesia dissolves to a small extent (O-lyo) in mixtures of mag-nesium fluoride with alkali and alkaline-earth fluorides molten a t750-950°, and electrolysis of the melt yields metallic magnesiumof relatively high purity and, in particular, free from hygroscopicimpurities such as lead to rapid corrosion.Apparently the primaryaction is electrolysis of magnesium fluoride, but this compound isregenerated by reaction between the liberated fluorine and magnesiadissolved in the melt.44Some interesting experiments may be recorded upon the use of azinc arc as a means of reduction. If a direct-current arc is main-tained between a zinc anode and carbon cathode immersed in liquidcarbon disulphide a t O", a considerable yield of carbon subsulphide,about 50% of that expected according to the reaction 3CS2+4Zn -+dl A. Gaschler, Nature, 1925, 116, 396; A., ii, 925.4 2 A. Stock, P. Praetorius, and 0. Priess, Ber., 1925, 58, [B], 1571; A., ii,a3 F. Krauss and H. Gerlach, 2. anorg. Chem., 1924, 140, 61; A., 1925, ii,44 W. G. Harvey, Trans. Amer.Electrochem. Soc., 1925, 47, 220; 0. Ruff1090.314.and ItT. Busch, Z . anoyg. Client., 1925, 144. 87; A . , ii, 570, 669fio ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.C3S2 + 4ZnS, is obtained. With silicon tetrachloride at - 55"to - 15", using an aluminium cathode, the zinc arc produces mainlysilicon with some hexachlorodisilane (m. p. + 2.5"), and undersimilar conditions phosphorus trichloride yields mainly yellowphosphorus with some dichloride, P2C14, m. p. - 28", whilst borontrichloride gives chiefly boron with a small quantity of a new chloride,B2C14, m. p. - loo", b. p. 0°/44 mm. This chloride decomposesslowly a t the ordinary temperature into boron and boron trichloride,yields with water a fairly stable compound containing the BOBgroup, and with aqueous sodium hydroxide gives hydrogen accord-ing to the scheme B2C14+ 3H20 + B20, + 4HCl+ H,. Asthese effects are profoundly modified by the use of alternatingcurrent, they are not solely attributable to the reducing action ofzinc vapour a t arc temperatures.45When excess of hydrogen peroxide is added t o aqueous barytabelow 20", the white, crystalline hydrate, Ba0,,8H,O, first formedchanges to a buff -coloured, granular precipitate which, on dryingin a vacuum over phosphoric oxide, becomes a cream or buff-coloured, non-crystalline powder. This substance decolorisespotassium permanganate more rapidly than does barium dioxide,it liberates iodine from potassium iodide and bromine from potass-ium bromide in presence of nitric acid, and it reacts vigorouslywith sulphur but without formation of sulphur dioxide.It doesnot contain hydrogen peroxide, as this substance can be detectedneither in the moisture liberated from the solid on heating nor inthe ethereal extract of the solid. Analyses by decomposition ofthe solid a t 500-600" in nitrogen and by titration with permangan-ate in nitric acid solution show that the atomic ratio of oxygen tobarium is very approximately 3 : 1 ; hence it is apparently a newperoxide of the formula Ba0,.46Further work has confirmed the existence of calcium carbonatehexahydrate (d15" 1.789). It is formed by the action of atmosphericcarbon dioxide on sugar-lime solutions, is stable in such solutionsbelow 10.4", and above that temperature changes to a pentahydrate(dl? 1.834), stable between 10-4" and 17".No evidence wasobtained of the existence of lower hydrates and it appears thatabove 17" anhydrous calcium carbonate is the only stable phase.47An interesting observation has been recorded, applicable t o the.rapid estimation of many metals dissolved in mercury and, moreimportant, affording a rapid and efficient means of purifying mercuryfrom such metals. I n the latter operation a reasonable excess of4 5 A. Stock, A. Brandt, and H. Fischer, Ber., 1925, 58, [B], 643; A., ii, 570.4 6 (Miss) M. Carlton, J., 1925,127,2180; compare Ann. Reports, 1921,18,44.4 7 J. Hume, J., 1925, 127, 1036INORGANIC CHEMISTRY. 51the oxidising agent is used and thus such metals as zinc, man-ganese, cadmium, thallium, tin, lead, copper, chromium, iron,and bismuth are rapidly eliminated without loss of mercury.For example, by shaking with a concentrated solution of per-manganate in 6N-sulphuric acid containing a little ferric sulphate,14 grams of a mixture of zinc, cadmium, tin, lead, solder, andbismuth were completely removed from 480 grams of mercury,without loss of the latter, whilst shaking with a normal solution offerric sulphate in 2N-sulphuric acid removed 7 grams of zinc from200 grams of amalgam in 30 seconds.48Group I I I .In the course of a critical examination of methods of preparingboron, it has been found that "Moissan's boron," prepared byreducing boric oxide with magnesium, is a mixture of boron witha new oxide, B,O.Pure amorphous boron was obtained in smallyield by electrolysing a fused mixture of potassium carbonate,potassium chloride, and boron trioxide, using a carbon anode anda copper cathode, and fused boron by reducing Moissan's boronwith aluminium a t arc temperatures. Boron was found to replacegold, platinum, palladium, silver, mercury, copper, and lead fromtheir solutions, and hence, in the electrochemical series, occupies aposition just above lead.49 Alkali borates have been prepared ofa new type distinct from those previously known (MBO,, M,B,O,,M2BI0Ol6, M2B8013, and, probably, M,B,O,,,). Solutions ofpotassium tetraborate with excess of boric acid sufficient t o givea ratio B : K : : 2.5 : 1 yield at 115-120" microcrystalline prismsof the new pentaborate, K2HB,0,,2Hq0, which is more readilyobtained by heating concentrated aqueous potassium tetraboratea t 115-120" in a sealed tube and seeding the solution with thepentaborate.The corresponding sodium salt is easily obtained bysimple heating of borax and water a t 115" in a sealed t~be.~OGallium sulphate, Ga2(S0,)3,1SH20, has been found to be stablein air : the hydroxide is distinctly more acidic and less basic thanaluminium hydroxide. Solubility curves for gallium hydroxidein sodium hydroxide show a maximum a t about l0.3N-sodiumhydroxide, indicating the existence of trisodium gallate and mono-or &-sodium gallate as distinct phases, of which the former is solubleand the latter insoluble in water.514 8 A. S. Russell and D.C. Evans, J., 1925, 127, 2221.49 H. H. Kahlenberg, Trans. Amer. Electrochem. SOC., 1925, 47, 59; A., ii,50 V. Auger, Compt. rend., 1925, 180, 1602; A., ii, 697.51 R. Fricke and W. Blencke, 2. anorg. Chern., 1925, 143, 183; A., ii, 417.42552 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Earlier work having shown that thallium existed in two enantio-tropic forms and that the transformation of a- into p-thalliumwas accompanied by an abrupt change in the X-ray pattern, thisobservation was applied to redetermine the transition point, 231.3".Later investigation of the transition point by the thermal methodusing very pure electrolytic thallium gave the slightly higher value232.5" 0.5", which is preferred.52The technique devised in attempts to separate isotopes by theionic migration method has been developed and applied to theseparation of rare-earth mixtures.A 2 yo agar-agar gel containinga given mixture (0.5 N ) is placed in a long glass tube between similargels containing a faster kation (K') nearer the cathode and a slowerkation (Cr") nearer the anode. On electrolysis, the more mobilerare-earth katioii accumulates in the forward portion of the tube, andthe gel is then cut iqto slices and analysed. In three typical mixtures,yttrium-erbium, neodymium-praseodymium, and gadolinium-samarium, a very good separation was thus effected; with the firstpair, a long tube being used and the electrolysis continued for21 days, the purest fraction contained 99% of yttrium.53Pure metallic praseodymium has been prepared by electrolysisof the fused chloride, using a low current density.The praseo-dymia was prepared from cerium earth residues, several knownprocedures being used €or fractionation, of which the best was foundt o be fractional crystallisation of the double magnesium and man-ganese nitrates ; the final product probably contained less than 0.3');of impurity, chiefly neodymium and lanthanum. Praseodymium isa silver-white metal, corrodes rapidly in air, and is attacked slightlyby hot water and vigorously by free halogens and mineral acids;it has d2? 6.60, kindles in air at 290", but is not pyr~phoric.~*Metallic neodymium of moderate purity was obtained by electrolysisof the fused chloride containing a little sodium chloride; the firstproduct of electrolysis was the subchloride, NdCl,, which was sub-sequently reduced to the metal.Neodymium resembles praseo-dymium closely in appearance and in its reactions with air, water,and acids; it has d15' 7.05 and kindles in air a t 270"; it alloysreadily with iron, aluminium, nickel, and copper.55 Metalliccerium, free from iron, was obtained by electrolysing the fusedchloride in graphite cells with carbon anodes. It is very malleable62 G. Asahara, Sci. Papers, Inst. Phys. Chem. Ree. Tokyo, 1925, 2, 125, 253 ;A . , ii, 483, 645.53 J. Kendall and B. L. Clarke, Proc. Nut. Acad. Sci., 1925, 11, 393; A., ii,977.54 J. Wierda and H. C. Kremors, Trans. Amer. Electrochem. SOC., 1925, 48,6.5; A . , ii, 993.5 5 H. C.Kremers, ibid., 1925, 47, 221; A . , ii, 588INORGANIC CHEMISTRY. 53and ductile, moderately pyrophoric, and corrodes easily in dry air ;it has d15" 6.77 ; Brine11 hardness (500 kg.) 21 ; heat of combustion1.661 Cal./g. ; kindling temperature 165°.56Group IV.Colourless diamond has been found to have a heat of combustion7873 & 4 Cal./g. as compared with 7884 3 2 for carbonado,7856 & 1 for P-graphite, and 7832 & 1 for a-graphite, whence itwould appear, contrary to earlier results,57 that a t the ordinarytemperature white diamond is a less stable form than graphite.The relatively high value for carbonado may be explained on theassumption that it consists of white diamond containing a propor-tion of amorphous carbon having a heat of combustion of about8060 Cal./g.5* The transformation of diamond into graphite athigh temperatures is comparatively slow in a vacuum, beingincomplete in an hour a t 1500-1900", in marked contrast with therapid change in presence of gases ; it occurs more rapidly a t 2000",although sometimes without the swelling and disintegration observedin gaseous atmospheres, and the rate differs greatly for differentspecimens. 59Further pursuit of experiments previously reported 6o has affordedstrong evidence that carbon can be fused a t atmospheric pressure.Carbon rods 99.9% pure and constricted in the middle were heatedelectrically in an atmosphere of argon and observed by means of akinematograph camera.As the current was increased, no gradualdiminution of the cross section of the rod occurred, but a bright linesuddenly appeared a t the narrowest part, where, less than 0.1 secondlater, the rod parted and formed an arc.Afterwards, small globules,of equal density, were found in the vicinity of the arc, whence itseems clear that the rod parted by fusion and not by sublimation.The temperature of the rod a t the moment of parting, measuredby a radiation pyrometer, was independent of the pressure between0.21 and 0.935 atm., and this value, 3800" +- 100" Abs., was taken asthe melting point. The temperature of the arc formed was foundto depend on the pressure, varying from 3450" Abs. at 0.005 atm.t o 4330" Abs. a t 1.5 atm., and these values above 3800" Aba. arebelieved to represent the boiling point of graphite a t different56 H. C.Kremers and H. Beuker, Trans. Amer. Electrocheirb. SOC., 1925, 47,5 7 Berthelot and Petit, Ann. Chim. Phys., 1889, 18, 80.5 * W. A. Roth and W. Naeser, 2. ElektTochein., 1925, 31, 461 ; A., ii, 1140.~59 P. Lebeau and M. Picon, Conzpt. rend., 1024, 179, 1059; A., 1925, ii, 136.cQ Ann. Repork, 1922, 19, 49.213; A., ii, 58154 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.temperatures.61 This value for the melting point of carbon hasbeen independently confirmed by another method yielding thevalue 3760" & 65" Abs.62More detailed rontgenographic examination of amorphouscarbons indicates that, contrary to previous conclusions, amorphouscarbon is a true modification distinct from graphite.63The vapour-pressure curve of carefully purified hydrogen cyanidehas been determined, in one case 64 from 0" to 46', in another 65from - 15" to 180".I n the latter case, the critical constants,Tc = 183.5' &- O e l " , P, = 53.2 If 0.5 atm., dc = 0.195, were alsodetermined, whence the molecular latent heat of evaporation iscalculated as 6.76 kg.-cal. a t 25.6" (b. p.) and 7.22 kg.-cal. a t- 13.4" (m. p.).Surface " devitrificatioii " of fused silica vessels and tubing iswell known to occur in use; eventually the change proceeds so farthat the ware becomes fragile and useless. It is, therefore, ofconsiderable practical interest to know that it is due to a trans-formation, probably to cristobalite, which is greatly hastened bythe presence of crystal nuclei or "slag" particles and can beprevented or greatly minimised if, as soon as the change becomesnoticeable, the corroded surface layer is removed by momentaryimmersion in aqueous hydrofluoric acid containing a little sulphuricacid.Silica thus treated becomes clear and smooth and its usefullife is prolonged.66The properties of monogermane have been further investigated :it has m. p. - 165", b. p. - go", and its density as liquid a t - 142"is 1.523. Analysis has confirmed the formula GeH,, and thenormal litre of the gas weighs 3.420 grams. It decomposes intogermanium and hydrogen a t about 280".67 Independent deter-minations upon monogermane prepared by electrolysis of a sulphuricacid solution of germanium dioxide with lead electrodes and purifiedby condensation with liquid air and fractionation in Stock's61 E.Ryschkewitsch, 2. Elektrochem., 1925, 31, 54; A , , ii, 276; see alsoH. Kohn and M. Guckel, 2. Physik, 1924,27, 305 ; K. Fajans, 2. Elektrochem.,1925, 31, 63; A., ii, 100, 277.62 H. Alterthum, W. Fehse, and M. Pirani, ibid., 1925, 31, 313; A., ii, 759.63 0. Ruff, G. Schmidt, and W. Olbrich, 2. nnorg. Chem., 1925, 148, 313;64 R. Hara and H. Sinozaki, Tech. Rep. T6hoku Imp. Univ., 1924, 4, 145;6 5 G. Bredig and L. Teichmann, 2. Elektrochem., 1925, 31, 449; A., ii,66 F. C. Vilbrandt, Ind. Eng. Chem., 1925, 17, 835; A., ii, 1091.137 R. B. Corey and A. W. Laubengayer (with L. 31. Dennis), J . Amer.A., 1925, ii, 1125.A., ii, 279.950.Chern, SOC., 1925, 47, 112; A., ii, 493fNORd ANIC CHEMISTRY, 55apparatus confirm the foregoing data (b.p. - 88.5", m. p. - 164.5",mol. heat of evaporation 3.65 kg.-cal.; 68 b. p. - 90" to - 91°).6gGermanium glasses of four types, a very dense flint, a flint, aborate crown, and a barium crown glass, have been prepared andcompared in each case with a corresponding silicate glass in whichgermanium dioxide was replaced by an equimolecular proportionof silica. The germanium glasses closely resemble the silicate glassesexcept that the former have higher refractive indices and, as theymelt a t considerably lower temperatures, can more easily beobtained homogeneous and free from air bubbles. 70Tin hydride has been obtained in a state of fair purity (99.7%)by electrolysing a solution of tin sulphate between lead electrodeswith the addition of certain colloids (e.g., 0.5% of dextrin) to theelectrolyte, whereby the yield is increased and the product stabilised.The maximum concentration of hydride thus obtained in theevolved hydrogen is about 0.01 yo, but after the gas has been washedwith water and alkaline lead acetate solution, and dried by passagethrough tubes cooled to - 80" to - loo", the tin hydride may becondensed in liquid air and purified by fractional distillation andfractional condensation a t low temperatures.The hydride isrelatively stable at the ordinary temperature, decomposing onlyafter some days in glass vessels, but it is very sensitive and isdecomposed rapidly at ground glass joints, a t tin mirrors (evenwhen these are invisible to the naked eye), and in contact withcalcium chloride and phosphoric oxide.It decomposes rapidlyand completely a t about E O " , and it has thus been analysed andshown to have the formula SnH4. The solid hydride melts a t- 150" (& 2"). The gas does not react with aqueous alkali hydr-oxides (up to 15%), dilutc sulphuric acid, dilute or concentratednitric acid, sodium carbonate, copper sulphate, ferric chloride, orlead acetate, but is absorbed partly by concentrated sulphuricacid and strong aqueous alkali hydroxides and completely bysolid alkali hydroxides, soda-lime, and aqueous silver nitrate.In the last case, a black precipitate is formed containing both tinand silver.Reference may here be made t o an interesting general discussionof the group of volatile hydrides, of which the foregoing are mem-bers, where i t is held that the close physical similarity of these6 8 F.Paneth and E. Rabinox-its&, Ber., 1925, 58, [R], 1138; A., ii, 760.6s R. Schenk and A. Imker, ibid., 1925, 58, [B], 271; A., ii, 279.70 L. M. Dennis and A. W. Laubengayer, J. Amer. Chem. h%C., 1925, 4'9,1945; A., ii, 888.'1 F. Paneth and E. Rabinovitsch, Ber., 1924, 5'9, [B], 1877; F. Paneth,W. Haken, and E. Rabinovitsch, ibid., 1924, 5'9, [B], 1891; A . , 1925, ii,59, 6056 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.hydrides to the rare gases indicates that the hydrogen nucleiare " buried " in the molecule, which, therefore, presents a " rare-gas " surface.68A good deal of work has been done on zirconium and hafnium.These metals (and also titanium and thorium) are deposited inthick layers on a tungsten filament heated in the vapour of theappropriate iodide; it is stated that hafnium is denser thanzirconium, and has a 'higher melting point and a higher electronemission.72 Zirconium and hafnium phosphates precipitated fromGN-hydrochloric acid have the composition MO(H,P04), ; 73 theyare soluble in concentrated sulphuric or phosphoric acid and inoxalic acid and are reprecipitated on dilution or in the last caseon addition of alcohol or mineral acids; the solutions of hafniumphosphate are the less stable, and fractional precipitation as phos-phate constitutes an important step in the separation of hafniumand zirconium.74 These phosphates are also easily soluble inhydrofluoric acid and a method for separating hafnium and zir-conium has been based on this fact.'5 Further purification is insome cases effected by fractional solution in saturated sodiumcarbonate solution.76 A better method appears to be fractionationas ammonium and potassium double fluorides; by warming thecrude dioxides with ammonium fluoride and hydrofluoric acid,double fluorides of the type (NH,),RF, are obtained which areunsuitable for fractionation ; these are therefore converted intothe fluorides (NH4)zRFe (R = Zr, Hf), which are fractionallycrystallised until the hafnium content, originally 2-5%, is raisedto 38 yo. Subsequently fractionation by recrystallisation of thepotassium salts, K,RF6, may be made to yield a hafnium salt ofmore than 99.9% purity; in all these cases the hafnium salt isthe more soluble.77 Another interesting method of separation hasbeen proposed depending upon fractional distillation of the com-pounds 2RC14,PC1, : the zirconium compound, previously de-72 A.E. van Arkel and J. H. de Boer, 2. anorg. Chem., 1925, 148, 345;A., ii, 1193.73 G. Hevesy and K. Kimura, J . Amer. Chem. Xoc., 1925, 47, 2540; A., ii,1147.74 J. H. de Boer and A. E. van Arkel, 2. anorg. C'hcrn., 1925, 148, 84; A.,ii, 1185.7 s Idem, ibid., 1925, 144, 190; A., ii, 705.75 (Mlle.) M. AIaxquis, P. Urbain, and G. Urbain, Cotnpt. rend., 1925, 180,1377; J. Bardet and C. Toussaint, ibid., 1925, 180, 1936; A., ii, 699, 826.7 7 J.H. de Boer and A. E. van Arkel, 2. anorg. Chem, 1924, 141, 284;G. von Hevesy and E. Madsen, 2. angew. Chena., 1925,38,228 ; G. von Hevesy,J. L4. Christiansen, and V. Berglund, 2. anorg. Chem., 1925, 144, 69; A., ii,243, 425,505 ; see also Naamlooze Venootschap Philips' Glocilampsnfabriken,Yr. Pats. 568978 and 569016INORGANIC CHEMISTRY. 57scribed,7* is a white, crystalline solid, m. p. 164~5"~ b. p. 416",readily hydrolysed to form a compound, 2ZrCl,,POC13; this is itvitreous solid, b. p. 363-364", which can easily be reconvertedinto the former compound by the action of phosphorus penta-chloride. Hafnium forms analogous but rather more volatilecompounds, and thus, by repeated distillations, can be concen-trated in the head fractions : titanium and silicon chlorides aremuch more volatile, whilst iron and aluminium form additivecompounds much less volatile than those of hafnium and zir-conium; hence these impurities are eliminated a t an early stageof the fracti~nation.~~Group V .When nitric oxide is bubbled through liquid oxygen, or air actson solid nitric oxide a t - 185", a green solid is formed whicha t a slightly higher temperature is converted into a blue solid;analysis shows this to be the oxide N,O,.*O It is now reported thatthe green solid is a new oxide of nitrogen, nitroso-nitrogen trioxide,(N304)s.The conversion of this oxide into nitrogen trioxide isapparently irreversible and it is assumed, because of its instabilityand its instantaneous formation, that it is a peroxidised polymerideof nitric oxide produced according to the scheme :A similar explanation may be applied to the phenomena observedin the oxidation of nitric oxide at higher temperatures, supposing(NO), to yield O:N*NO-O*O-NO*N:O and NO to yield 0:N*0*0*N:0.81The nitric oxide compound of ferrous selenate, the seleniumanalogue of that responsible for the " brown ring " test, is obtainedby saturating with nitric oxide concentrated aqueous ferrousselenate (FeSeOp,5H,0) containing a little selenic acid.On coolingand adding a large excess of absolute alcohol saturated with nitjricoxide, brownish-black crystals are obtained, apparently having theformula FeSe04,N0,4H,0, which are unstable and lose nitric oxidewhen kept in air.82'* Paykiill, Ber., 1879, 12, 1719.A.E. van Arkel and J. H. de Boer, 2. anorg. Clzem., 1924, 141, 2S9;A., 1925, ii, 243.D. Helbig, Atti R. Accad. Lincei, 1903, 5, 166; A., 1903, ii, 361. Thisblue solid was also said, erroneously, to be N,O, ; F. Raschig, C?&em.-Ztg., 1911,35, 1096; A., 1912, ii, 346.R. L. Rasche, ,7. Amer. Chena. Soc., 1925, 47, 2143: A., ii, 988.82 W. Marichot andE. Linckh, Z . anorg. Chena., l924,140,37;A., 1925, ii, 31758 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Three independent investigations confirm the view that thethermal decomposition of nitrogen pentoxide is a true unimolecularreaction ; the temperature coefficient is very large (300% velocityincrease for 10" rise), hence there is probably no wall effect, andthere is no evidence that the reaction is autocatalytic.83An extremely interesting paper on the constitution of nitricacid must be inadequately summarised : consideration of absorptionspectra and electrical conductivity leads to the view that strongnitric acid is an equilibrium mixture of the pseudo-acid O,N*OH,the true acid present as the hydroxonium salt, (NO,)[H*OH,],and the salt-like electrolyte nitronium nitrate, (N0,),[(HO)3N],the proportion of the second-named being negligible in almostanhydrous nitric acid.The conception of nitronium salts isstrengthened by the fact that mixtures of almost anhydrous nitricand perchloric acids deposit nilronium diperchlorate,(c104)2[ (HOhNIm. p. 130" with decomposition, and nitronium monoperchZorate,ClO,[(HO),NO], decomposing above 130°, as stable salts whichcan be crystallised from perchloric acid and nitric acid, respectively.The reactions between perchloric, sulphuric, and nitric acids, ofwhich the foregoing are typical, are held to afford strong evidencefor the chemical theory of acids according to which their strength(acidity) is measured by their tendency toward salt formation andnot by their ability to furnish hydrogen i0ns.8~The previously unknown nitrides of zirconium, niobium, scand-ium, and erbium have been prepared by heating the correspondingoxides with the calculated quantity of carbon a t 1250" in nitrogen;they are solids of high melting point.85Nitrogen tetraselenide, prepared by passing a rapid stream ofammonia gas through a cooled solution of selenium monochloride incarbon disulphide and allowing the resultant solution to evaporate,was used for a determination of molecular weight by the cryoscopicmethod in glacial acetic acid, whence the formula is N4Se4.Nitrogentetrasulphide was obtained in good yield from sulphur monochlorideby a similar method, and both sulphides were observed to yield,on prolonged treatment with ammonia, dark coloured liquids,presumably additive compounds, characterised by a most offensiveodour.86 Sublimation of nitrogen sulphide containing free sulphur83 H. S. Hirst, J., 1935, 127, 657; E. C. White and R. C. Tolman, J. Amer.Chem. SOC., 1925, 47, 1240; J. K. Hunt and F. Daniels, ibicl., 1925, 47, 1602;A., ii, 554, G82, 801.84 A.Hantzsch [with L. Wolf], Ber., 1925, 58, [BJ, 941 ; A., ii, 634.86 E. Friederich and L. Sittig, 2. anorg. Chem., 1925, 143, 293; A., ii, 419.86 H. B. van Valkenburgh and J. C. Bailar, J . Amer. Chem. SOC. 19254'7, 2134; A., ii, 993INORGANIC CHEMISTRY. 59over silver gauze a t about 125" yields a film of a ruby-red com-pound which on keeping or a t 50" turns deep blue and behaves asblue nitrogen sulphide; in the absence of sulphur, the blue com-pound only is obtained. Sublimation of nitrogen sulphide withsulphur a t 125" in the absence of silver gauze produced smallquantities of a dark red, easily volatile liquid, resembling bromineand having an odour like that of iodine; it formed a pale yellowsolid a t - 80" and on analysis by decomposition gave data corre-sponding with the formula NS,; it is therefore regarded as a newnitrogen persulphide.87Dry bromine vapour reacts with sodium or silver azide, givingbromoazoimide, N,Br.This substance is extremely unstable,decomposing explosively on shock in all states of aggregationand even a t - 200"; it melts at about - 45". Bromoazoimide isinstantly hydrolysed by water, consequently bromine water reactswith sodium azide to form sodium bromide, azoimide, and hypo-bromous acid, and these further react, forming nitrogen. Hypo-bromous acid reacts even more rapidly with sodium azide, so thattwo equivalents of bromine are able to decompose two equivalentsof sodium azide.87aExtension of work previously reported 88 has shown that thespectrum of the glow of phosphorus trioxide is identical with thatof the glow of phosphorus and that the burning of hydrogen phos-phide in air shows the same ultra-violet bands with certain differ-ences in intensity.From these and other facts it is inferred thatlow-temperature combustion of phosphorus, the trioxide, andthe trihydride involves a common stage responsible for the chemicalanomalies and intimately associated with the characteristic light-emission .89Group V I .Further physical constants of ozone have been determined asfollows : m. p, - 251.4", b. p. - 112.3", critical temperature - 5",critical pressure (calculated) 67 atm., critical density 0.64, criticalvolume 89.4 c.c./mol., density of liquid a t - 183" 1-71 &- 0.06;the critical solution temperature of liquid ozone and liquid oxygenis - 155°.90 It has been found that appreciable quantities ofozone, much in excess of those to be anticipated by thermal form-ation, are produced by passing dry oxygen through quartz capillaries87 F.L. Usher, J., 1925, 127, 730.87a D. A. Spencer, J., 1925, 127, 216.89 H. J. Emel&us, Nature, 1925,115, 460; J., 1025, 127, 1362; A , , ii, 364,O0 G. M. Schwab, 2. physikal. Chern. 1924, 110, 599; A., 1925, ii, 149.Ann. Reports, 1924, 21, 46.74060 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.a t 750-1250', and that presence of moisture reduces the yield ofozone. This coniirms the view that hydrogen peroxide plays nopart in ozone f~rmation.~lBecause the provision of a convenient supply of hydrogen sulphideis a perennial laboratory problem, it seems worth while to directattention to the fact that a copious supply may be obtained bygently heating a mixture of sulphur and paraffin wax; the gener-ation of gas ceases almost immediately on withdrawing the sourceof heat and when a charge is spent it may easily be renewed if theprecaution is taken to mix the materials originally with ignitedasbestos.92 A number of compounds of metallic halides withhydrogen sulphide, named " thiohydrates," have been proved toexist and are formulated as follows : BeBr2,2H2S ; BeI,,2H2S ;A1CI3,H,S ; A1Br3,H,S ; A113,2H,S ; A11,,4H2S ; TiCI,,H,S ;TiC1,,2H2S ; TiBr4,H,S ; TiBr4,2H2S ; SnCI4,2H2S ; SnC14,4H,S.93Whilst it has long been known that sulphur reacts with sulphurtrioxide to produce a bluish-green solid and a blue liquid andWeber94 found the sulphur content of the bluish-green solid tocorrespond with the formula S,03, it has latterly been generallybelieved that the supposed sulphur sesquioxide was a " colloidalsolution." It has now been found that on adding pure redistilledsulphur to pure sulphur trioxide under careful exclusion of moisture,a violent reaction sets in after 30 seconds and a bluish-green solidis formed.The excess of sulphur trioxide may be removed bydistillation in a vacuum a t 30-40', and, although the substancebegins to decompose after a few minutes a t 15", it was possibleby two distinct methods of analysis to prove that the sulphurcontent was that required by the formula S203 and hence thatsulphur sesquioxide does exist.It is at once decomposed by water,with deposition of sulphur and formation of sulphuric, sulphurous,tri-, penta-, and possibly tetra-thionic acids. With sodium ethoxidein alcoholic solution, it forms sodium ethyl sulphoxylate, NaEtSO,,which on hydrolysis yields sodium sulphoxylate as a white, crystal-line solid moderately soluble in cold water and sparingly solublein alcohol, and practically unattacked by boiling concentratedsuZphuric and hydrochloric acids .95 The production of thionic acidsfrom sulphur sesquioxide and the known reactions and properties91 E. H. Riesenfeld, 2. EEektrochem., 1925, 31, 435; A., ii, 989 (compareAnn. Reports, 1924, 21, 48; E.H. Riesenfeld, 2. physikal. Chem., 1924,110,801; H. von Wartenburg, ibid., 1924, 110, 285; A., 1925, ii, 148, 147).92 A. Henwood, R. M. Carey, W. Goldberg, and E. Field, J. PrunklinInst., 1925, 199, 685; A., ii, 705.93 W. Biltz and E. Keunecke, 2. unorg. Chem., 1925, 147, 171; A., ii, 986.94 Weber, Ann. Phys. Chenb., 1875, 156, 531.95 I. Vogel and J. R. Partington, J., 1925, 127, 1614INORGANIC CHEMISTRY. 61of these acids and their salts have led to the followingformuh : 96SO,*OH S.S.s<S02*OHSO,*OH' . . SO,-OH SO,*OHSO,*OH '<S02*OH S:S<SO,*OHI Dithionic acid. Trithionic acid. Tetrathionic acid. Pentathionic acid.Solubility determinations for sodium and potassium sulphites pre-pared and handled in an atmosphere of hydrogen give no evidencefor the existence of NaHSO, or KHSO,, but show that only pyro-sulphites crystallise from acid solutions.Potassium pyrosulphiteis anhydrous at all temperatures and sodium pyrosulphite inequilibrium with its solution is anhydrous down to 5-5" and belowthat temperature may form a stable phase with 7 mols. of wateror a metastable phase with 6 mols. of water. The thermal decom-position of calcium, sodium, and magnesium sulphites has alsobeen studied in some detail.97 Work on the decomposition ofpolythionates in aqueous solution, on the influence of thiosulphateand sulphite on their stability, and on the action upon them ofalkali and hydrogen sulphide can only be referred to here.98Selenium monochloride and monobromide have hitherto beenprepared in absence of water, with the attendant experimentalcomplications, but it is now shown that these compounds mayeasily be prepared in quantity by dissolving the dioxide in theappropriate halogen acid and adding the requisite quantity ofelementary selenium.Gradual addition of excess of concentratedsulphuric acid then precipitates the selenium monohalide as an oilwhich can be separated and purified in the usual manner: theyield is 90%.99 Careful comparison of properties shows that thecompounds of selenium dioxide with the halogen acids, Se02,2HC1and Se02,2HBr, are identical with the hydrates SeOCl,,H,O andSeOBr,,H,O : the latter compound is obtained as a reddish-brownoil when hydrogen bromide is passed over selenium dioxide; ithas d2y 3,077; a t 115", it begins to decompose, yielding bromine,selenium monobromide, tetrabromide, and oxybromide, seleniumdioxide, water, and hydrogen bromide.On cooling the liquid to- lo", red selenium tetrabromide crystallises out; on a,ddition ofselenium dioxide, yellow needle crystals of SeOBr,, m. p. 40", are96 I. Vogel, J., 1925, W, p. 2228.97 F. Foerster, A. Brosche, and C. Norberg-Scliulz, 2. physiEaZ. C'hein.,1924, 110, 435; F. Foerster and K. Kubel, 2. anorg. Chem., 1924, 139, 361 ;A . , 1925, ii, 120.9* A. Kurtenacker and M. Kauffmann, 2. anorg. Chem., 1925, 148, 43, 225,256, 369; A., ii, 1189, 1190.90 V. Lenher and C. H. Kao, J . Amer. Chem. SOC., 1925, 47, 772; A., ii,42662 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.obtained, but stronger dehydrating agents, such as sulphuric acid,precipitate the tetrabromide.Selenium oxychloride may be con-veniently prepared by dehydrating the compound Se02,2HC1 with70% sulphuric acid: so obtained, it has m. p. 10-9", b. p. 176",The usual'methods for preparing selenic acid by oxidation ofselenious acid with halogen give a product of doubtful purity andinvolve removal of halogen acid by addition of silver carbonate orsome equivalent device., A much simpler and better method isrendered possible by the fact that the selenites of the alkali metalsand of barium and strontium are easily converted into selenates byroasting them in air; the preparation of the selenites may beeffected in the same operation by starting with a mixture of seleniumor selenium dioxide and metallic carbonate.If a solution ofpotassium selenate is precipitated with a slight excess of perchloricacid and the latter is distilled from the filtrate under reducedpressure, selenic acid of high purity is easily ~btained.~Molybdenum pentoxide is obtained by heating the oxysulphateor the oxyoxalate of tervalent molybdenum in a current of nitrogen :Mo20(S04), --j. Mo,O, + 2S0,; Mo,0(C204), -+ Mo,05 + 4CO.*Metallic tungsten has been obtained as powder or as a coherentdeposit on copper, nickel, or cobalt, by electrolysis of moltensodium tungstate at 950", with addition of tungstic oxide, and adetailed study has been made of the binary systems of lithiumtungstate with sodium tungstate and potassium tungstate and oftungsten trioxide with each of the f~regoing.~ Complex uranylcarbonates of silver and barium, Ag4U0,(C03)3 andhave been described.6d22" 2-424.1Ba,UO,(C0,)3,6H,O,Group VII.When chlorine dioxide is exposed to light, a dark-red oil is pro-duced reported in one case to be chlorine heptoxide, b.p. aboutSO", and in another to be chlorine hexoxide, C1,0, having a verylow vapour pressure, 1 mm. a t 20", d20" 1.65, and m. p. - 1" :1 C. W. Muehlberger and V. Lenher, J . Amer. Chem. SOC., 1925, 47, 1842 ;2 V. Lenher and C. H. Kao, ibid., p . 1521; A., ii, 817.4 W. Wardlaw and F. H. Nicholls, J., 1925, 127, 1311, 1487.6 J. A. M. van Liempt, 2. Elektrochem., 1925, 31, 249; 2. anorg. Chem.,A., ii, 890.V. Lenher and E, J.Wechter, ibid., p. 1522; A., ii, 815.1925, 143, 285; A,, ii, 694, 421.J. A. Hedvall, 2. anorg. Chern., 1925, 146, 225; A., ii, 990.and E. Padelt, 2. anorg. Chem., 1926, 147, 233; A., ii, 573, 991.7 H. Booth and E. J. Bowen, J., 1925,127,510; M. Bodenstein, P. HarteckINORGANIC CHEMISTRY. 63further work on this matter is evidently necessary to reconcilethese conflicting conclusions.Two pseudo-halogens have been obtained as free radicals.Electrolysis of an alcoholic solution of potassium cyanate with aflowing mercury cathode yields a solution containing oxycyanogen,(OCN),, which has not been isolated but in solution has an odourlike that of the halogens, liberates iodine from potassium iodide,and dissolves copper, zinc, and iron without evolution of gas.Selenocyanogen, (SeCN),, is prepared by the action of iodine a t 10”on excess of silver selenocyanate in ether, chloroform, or carbontetrachloride ; evaporation of the filtered solution yields seleno-cyanogen as a yellow, crystalline powder exhibiting the propertiestypical of halogens; it can be preserved in a vacuum, but becomesred in a few hours on exposure to air.*Three allotropic forms of manganese exist, a, p, and y, of whichthe p- and y-forms are present normally in commercial manganese ;a-manganese can only be obtained electrolytically, the 7-form isproduced when manganese is heated above 850” in a vacuum andsuddenly quenched, and the p-form is obtained from y-manganeseby sublimation in a vacuum at 1105°.9 I n the course of investig-ations on the oxidation of manganous salts to permanganic acidand on the reduction of that acid by arsenious acid, mangagcfluoride, orthophosphate, metaphosphate, and orthoarsenate havebeen described.1°Element No.75, Mendelbeff’s (‘ dvi-manganese,” has beendiscovered. Noddack and Tacke state that they have found tracesof elements 43 (eka-manganese) and 75 (dvi-manganese) in platinumores and in columbite and that examination of the X-ray spectrumof concentrates derived therefrom indicates the presence of 0-5 yoand 5%, respectively, of these elements. There seems, however,some doubt whether they have in fact obtained these elements, asthe X-ray spectra are inconclusive. These observers also reportthat tantalite and tungstite contain traces of element No.75 andthat sperrylith, gadolinite, fergusonite and zircon contain traces ofelement No. 43; they propose the names ‘(rhenium” andmasurium,” respectively, for these elements.llDruce and Loring, in the course of a search for element 93 inmanganese salts, after an urisuccessf ul attempt to effect a separation6 68 L. Birckenbach and K. Kellermann, Ber., 1925, 58, [B], 786; A,, ii, 568.9 A. J. Bradley, Phil. Mag., 1925, [vi], 50, 1018; A., ii, 1124.lo A. Tmvers, Bull. SOC. chirn., 1925, [iv], 37, 456; A., ii, 585.l1 W. Nodclack and I. Tacke, Naturwiss., 1925, 26, 567; W. Noddack, I.Tacke, and 0. Berg, Sitzungsber. Preuss. Akad. Wiss. Berlin, 1926, 400; A.,ii, 93964 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.by fractional crystallisation, obtained preparations comparativelyrich in dvi-manganese from the residual solution left after precipit-ation of the manganese as sulphide in an ammoniacal solution.The X-ray spectrum of the oxide thus obtained, photographed inthe research laboratory of Messrs.Adam Hilger, Ltd., gave definiteLa and Lp lines of element No. 75. Independently Dolejgek andHe yr ovsk y, by polar ogr a phic - elec t ro - anal y si s with a droppingmercury cathode, have obtained evidence of the presence of dvi-manganese in manganese sulphate solutions, and have confirmed thepresence of dvi-manganese in the products obtained by Druce andLoring.These workers, whose priority in publication is admitted byDolejgek and Heyrovsky, prefer the name dvi-manganese to thename " rhenium " proposed by Noddack and Tacke.As yet, little is known of the chemistry of dvi-manganese exceptthat the sulphide is not precipitated in ammoniacal solution, thatthe chloride is apparently volatile, that the oxide is insoluble incaustic alkalis though turned brown by them, and that an unstablepotassium dvi-manganate can apparently be obtained.Furtherwork on this element will be awaited with keen interest by allchemists .I2Group V I I I .By the action of potassamide on cobaltous thiocyanate in liquidammonia solution cobaltous amide, Co(NH,),, is obtained and thisat 120" loses ammonia to form cobaZtous nitride, Co,N,, as a blacksolid almost unaffected by water ; the action of iron wire on mercuricthiocyanate in the same solvent yields ferrous tetramminethiocyanate,Fe(SCN),,4NH3, which is converted by potassamide into ferrousnitride, Fe3N2.l3 A large number of complex cobaltic selenateshave been described.14Ruthen-ium tetroxide is obtained in a state of purity by distilling at 40-50"in a current of air an acidified solution of a fused mass of ruthen-ium powder (l), potassium permanganate ( S ) , and potassiumhydroxide (20) ; it forms long, golden-yellow needles, readily solublein water.The solution is unaffected by hydrofluoric acid, butreadily oxidises the other halogen acids, liberating free halogen andA good deal of work on ruthenium has been published.l2 J. G. F. Druce, Chem. News, 1925,131, 273; A., ii, 1124; F. H. Loringand J.G. F. Druce, ibid., 1925, 131, 337; Dolejgek and Heyrovskj., Nature,1925, 116, 782; see also ibid., 1925, 117, 16.l3 F. W. Bergstrom, J . Amer. Chem. SOC., 1924, 46, 2631; A., 1925, ii, 231.l4 J. Meyer, G. Dirska, and F. Clemens, 2. anorg. Chem., 1924, 139, 333;A,, 1925, ii, 422INORGANIC CHEMISTRY. 65yielding halogen derivatives of ter- and quadri-valent ruthenium.15A quantitative investigation of these reactions l 6 affords strongevidence of the octavalency of ruthenium in the tetroxide. Adetailed study has been made of the lower oxides of ruthenium:pure ruthenium dioxide may be prepared by heating rutheniumsesquichloride, Ru2C13, a t 600-700" in oxygen and also by heatingin a vacuum the tetrahydroxide obtained by the action of hydrogenperoxide on the trihydr0xide.l' Further investigation of tetra-chlorodioxyruthenic acid, H,RUO,C~~,~H~O,~~ has resulted in theisolation of a new ruthenium ammine, Ru(NH,)~(H,O)~C~,, am-monium and potassium hexachlororuthenates, (Mt4),RuC1,,0~5H,Oand K,RuC16, and also a potassium pentachlororuthenite differingin many respects from those previously described.lg This workmust be considered in conjunction with an investigation directedespecially to the chlororuthenites.20Ruthenium pentafluoride has been prepared by direct unionof its elements a t 280" and forms a dark green, transparent mass,m. p. 101", b. p. 270-2275", c P 5 " 2.963.21Osmium tetroxide has been found to exist in two forms : thewhite needles produced when the vapour condenses in a cooledreceiver melt a t 39.5", boil at 134", and are readily soluble andreactive; when heated a t 40", they are converted into a yellow,sparingly soluble and non-reactive form, m. p. 41", which may bereconverted into the white form by cooling in liquid air or bysublimation. Both forms had the calculated osmium contentand liberated the calculated weight of iodine from potassiumiodide.22Iridium tetroxide has been obtained by heating the pure hydroxidein nitrogen a t 350°,23 and whilst attempts to prepare tetrahalidesof iridium were unsuccessful, the monobromide, dibromide, tri-bromide, monoiodide, and di-iodide were obtained.24 Lastly,l5 F. Krauss and H. Kukenthal, 2. anorg. Chem., 1924, 136, 62; A., 1925,l6 0. Ruff and E. Vidic, ibid., p. 49; A., 1925, ii, 480.l7 L. Wiihler, P. Balz, and L. Metz, ibid., 1924, 139, 205; A., 1925, ii,ii, 480.149.Ann. Reporb, 1924, 21, 54.lD Howe, J . Amer. Chem. SOL, 1901, 23, 775; A., 1902, ii, 86.2o S. H. C. Briggs, J., 1925, 127, 1042; see also R. Charonnat, Compt. rend.,21 0. Ruff and E. Vidic, 2. anorg. Chem., 1925,143, 163; A., ii, 443.22 F. Krauss and D. Wilken, 2. anorg. Chem., 1925, 145, 151 ; A., ii, 894;compare H. von Wartenburg, Annalen, 1924, 440, 97; 1925, 441, 318; A.,ii, 231, 276.1925, 180, 1271 ; A., ii, 586.23 F. Krauss and H. Gerlach, 2. anorg. Chem., 1925,143, 125; A., ii, 424.a4 Idem, &id., 1925, 147, 265; A., ii, 1089.REP.-VOL. XXXII. 66 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.reference may be made t o the isolation of a number of compoundsof carbon monoxide with halogen compounds of iridium, osmium,rhodium, and ruthenium.25H. V, A. BRISCOE.25 W. Maiichot and H. Gall, Ber., 1925, 58, [B], 232; W. Manchot andJ. Konig, ibid., 1924, 57, [BJ, 2130; 1925, 58, [B], 229, 2173; A,, ii, 232,149, 232, 1193

ISSN:0365-6217    

DOI:10.1039/AR9252200042

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

ORGANIC CHEMISTRY.PART I.-~IPHATIC DIVISION,THE number of contributions in this section published during theyear under review is again very large. The year has been markedby steady progress, with very definite achievements in certain groups,notably among the higher fatty acids and the complex carbo-hydrates. It has been found convenient to review the subjectof optical activity every other year, so a detailed report willappear in the volume for 1926. Attention may, however, bedirected in passing to a paper on the optical activity of the n-alkyl p-toluenesulphinates and to another dealing with thearrest of the mutarotation of tetramethyl glucose, each of whichappears to open up a wide field.Alcohols and their Derivatives.Methyl alcohol can be obtained in a highly purified condition3by fractionating through a Hempel column of an effective length of1.3 metres, and refluxing with aluminium amalgam. To removeammonia, it is then refluxed under a column packed with dehydratedcopper sulphate.By this means methyl alcohol having a con-ductivity of 0.04 reciprocal megohm has been prepared. To testfor the presence of impurities in methyl alcohol, a reagent consistingof a concentrated solution of mercuric cyanide in 6N-sodium hydr-oxide is suggested. A white precipitate indicates the presence of aketone ; if the precipitate darkens on keeping, an aldehyde also ispresent. The reagent will show the presence of 0.002% of acetoneor 0-004y0 of formaldehyde if either is present alone. The mostsensitive test for water is the variation observed in the electricalconductivity of a dilute solution of hydrogen chloride in the alcohol.Ethyl alcohol can be dehydrated by successive distillation withcalcium chloride until a concentration of 98% is attained.Cetylalcohol in a nearly pure condition can be easily and quickly pre-pared by hydrolysis of spermaceti in aqueous-alcoholic potassiumH. Phillips, J., 1925, 127, 2552.H. Hartley and H . R. Raikes, ibid., p. 524.T. M. Lowry, ibid., p . 1385.4 J. J. Sudboroughand P. R. Ayyar, J . Indian Inst. Sci., 1925, SA, 49; A.,i, 1125.M. A. Youtz, J . Arner. Chem. Soc., 1925, 47, 2252; A., i, 1125.c68 ANNUAL REPORTS ON THE PROGRESS OB CHEMISTRY.hydroxide solution followed by extraction, under specified conditions,with light petroleum.It is purified by conversion into the acetate,which may be distilled under reduced pressure.The use of magnesium alkyloxides in the synthesis of alcohols hasbeen examined.6 These are prepared by passing the vapours of thealcohols over magnesium at 270-280'. In 1 hour the reaction iscomplete and on raising the temperature to 400-410" for 2 to 3hours more, the alcohol vapour, by interaction with the ethoxide,produces the higher alcohol. Et,hyl alcohol is thus found t o givebutyl alcohol in 12-18y0 yield, whilst propyl alcohol gives di-propyl alcohol ( p-methylpentanol) in 30 % yield. Primary acetylenicalcohols, CRIC*CH,*OH, are obtained readily 7 by the action ofgaseous formaldehyde on the magnesium bromide derivative of thecorresponding acetylene.Phenylpropiolic alcohol, for example,may be prepared in this way and it is noteworthy that all theseacetylenic alcohols have a fragrant odour.A study of the production of glycerol by the fermentation ofsugar 8 shows that the hydrogen-ion concentration of the solutionis the deciding factor. The addition of sodium hydrogen sulphiteduring the fermentation, in quantities sufficient to maintain theproportion of free sulphite constant, has an important effect on theproduction of glycerol, the amount of which, under such conditions,approaches 40% of the sugar converted. The best method for thepreparation of the simple methylalkylglycerols would appear to bethe treatment of the dibromohydrin with potassium acetate fol-lowed by hydrolysis of the diacetate with methyl alcohol.Theyield of, e.g., methyl-n-propylglycerol by this method is about 40%compared with less than 20% by other processes.A number of new asymmetric tertiary alcohols of high molecularweight have been prepared from methyl nonyl ketone by theGrignard reaction.10 On dehydration of these alcohols with aceticanhydride or sulphuric acid, water is lost and an ethylenic hydro-carbon results. It is found that in most cases the elements of waterare eliminated by reaction between the hydroxyl group and ahydrogen atom from the largest alkyl group present, e.g., methyl-ethylnonylcarbinol yields y -methyl- by-dodecene.It was formerly supposed that the gossypyl alcohol obtained fromcotton wax was present in three varieties. A closer examination 11shows that this is not the case and that the alcohols actually present6 A.Terentier, Bull. SOC. chim., 1924, [iv], 35, 1145.H. H. Guest, J . Amer. Chem. SOC., 1925, 4'7, 860; A., i, 627.Y. Tomoda, J . Pac. Eng. Tokyo, 1924,15, 193; A., 1925, i, 227.R. Delaby and G. Morel, Cokpt. rend., 1925, 180, 1408; A., i, 773.lo H. Thoms and B. Ambrus, Arch. Phamn., 1925,263, 241 ; A . , i, 789.l1 J . Text. Inst., 1924, 15, T, 337; A., 1925, i, 879ORGANIC CHEMISTRY. 69in the wax of American cotton are (a) montanyl alcohol, C,,H,80,( b ) gossypyl alcohol, C,0H620, and, in smaller quantity, alcohols,C,,H,,O and C,,H,,O, together with a glycol, C,,H,,02, which isprobably a mixture. The wax-ester compounds isolated, includedgossypyl carnaubate, gossypyl gossypate, and montanyl montanate.The catalytic power of salts in promoting acetal formation appearsto be connected with their capacity to form alcoholates.12 All theknown catalysts for acetal formation give acid solutions with water,but that hydrogen ion is the catalyst is disproved by the fact thatcalcium chloride, e .g . , is more efficient than zinc chloride or ferricchloride. The velocity of acetal formation with hydrogen chlorideRS catalyst has h e n investigated in thirty-two cases. The velocity isleast with methyl alcohol, n-butyl alcohol being next, but secondary,and especially tertiary, alcohols react much more rapidly. Thehighest reaction affinities were observed when four carbon atomswere situated on either the alcohol or the aldehyde side of the acetal,and the lowest when the aldehyde had a double bond in the by-position, as in furfuraldehyde and cinnamaldehyde. Butaldehydehad the slowest reaction speed, whilst furfuraldehyde and hept-aldehyde, at the other end of the series, reacted several hundredtimes more rapidly.The method suggested by Ghysels 13 for thepreparation of the formals of primary alcohols has been applied l4 tothe preparation of acetals CH,*CH( OR),. The alcohol mixed withparaldehyde is heated with 1 to 2 % of p-toluenesulphonic acid. Theisolation of the product is complicated by the formation of binaryazeotropic mixtures between the alcohol and the acetal. Theacetal, however, can be separated from these by the addition ofcarbon disulphide, which forms, in most yases, a further azeotropicmixture with the acetal.Ethyl acetate of high, purity is obtained l5 by heating alcoholwith glacial acetic acid and 0.1 yo of sulphuric acid for 10 minutes.The best yield of ethyl acetoacetate was obtained by the action ofclean sodium on a mixture of pure ethyl acetate containing 5% ofabsolute alcohol.A stable solution of ethyl hypochlorite can beobtained l6 by shaking hypochlorous acid with carbon tetrachloridecontaining 2% of ethyl alcohol. The ester formed remains dissolvedin the carbon tetrachloride. The solution can be used a t a lowtemperature to study the action of ethyl hypochlorite on organicl2 E. W. Adams and H. Adkins, J .Amer. Chem. SOC., 1025, 47, 1358, 13G8;A., i, 784, 785.l3 A., 1924, i, 490.l4 J. B6dow6, Bull. Soc. chim. Belg., 1925, 34, 41.lii K. G. Roberts, J . SOC. Chem. Ind., 1924,43, 2 9 5 ~ .1 8 M. C. Taylor, R. B. McMullin, and C. A. Gammal, J. Amer. Chem. SOC.,The yields amount t o some 65%.1925, 47, 395; A., i, 50170 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.c0mpounds.~7 This appears to consist generally in the hydrolysisof the ester to ethyl alcohol and hypochlorous acid with subsequentaddition of the latter a t an aliphatic double bond. Amylene, forexample, gives amylenechlorohydrin. On the other hand, with1 : 4-dihydronaphthalene direct addition of the ester occurs, 3-chloro-2-ethoxy-1 : 2 : 3 : 4-tetrahydronaphthalene being the chief pro-duct.Ethyl hypochlorite was also found very suitable for thechlorination of primary and secondary amines, ethylamine, forexample, yielding ethyldichloroamine.I n continuation of his studies on keto-enolic desmotropy, H. P.Kaufmannls shows that the capacity to add bromine is not acharacteristic property of all enols, as it may be suppressed by stericinfluences, or by the presence of negative groups ; and further, thatsome enols do not give a characteristic coloration with ferric chloride.The discrepancies obtained in the determination of enol in ethyldiacetylsuccinate as well as in y-methylacetylacetone are shown tobe due to water in the iodide solution emp10yed.l~ With alcoholicsodium iodide solution, the difficulties disappear.A chelate ring structure for the enolic form of acetoacetic ester isproposed 2O in conformity with evidence already adduced in the caseof ortho-substituted phenols.The argument is based upon thestatement that if the enol is chelate it will not be associated and itsb. p. will be lower than that of the ketone, and its solubility will beless in water and more in non-polar solvents. For the enol ofethyl acetoacetate, the requisite data are available from the work ofMeyer and Scholler.21 These results show that the solubilities andboiling point are in agreement with the above hypothesis of a ringstructure and the consequent absence of a hydroxyl group in theenol, for which the following formula is suggested :9 IH*O*CMe:CH*C( 0Et):O.Aldehydes and Ketone$.A new methodZ2 for the synthesis of aldehydes consists in theconversion of a nitrile, through the imino-chloride, into an aldehydecontaining the same number of carbon atoms.Anhydrous stannouschloride, dissolved in ether saturated with hydrogen chloride, isthe most satisfactory reducing agent. The reactions which occur areas follows :17 S. Goldschmidt, R. Endres, and R. Dirsch, Ber., 1925, 58, [B], 572; A.,i. 502.H. P. Kaufmann and E. Richter, ibid., p. 216; A., i, 231.19 H. P. Kaufmannand J. Liepe, ibid., p. 1560; A., i, 1241.2o N. V. Sidgwick, J., 1925, 127, 907.21 Ber., 1920, 53, 1410; A., 1920, i, 707.22 H. Stephen, J., 1925, 127, 1874ORGANIC CHEMISTRY. 71R*CN + HCI -3- R*CCI:NH; RCCKNH + SnC1, + 2HC1-+R*CH:NH,HCl+ SnC1,.As examples of the utility of the method, n-octaldehyde, myrist-aldehyde, and stearaldehyde, besides a number of aromatic alde-hydes, have been prepared, the yields in many cases being almostquantitative.The term ketocyclic desmotropy has been appliedB to thedesmotropy existing between an open and a cyclic form such as thatassumed in the case of the sugars and edablished for y- and 6-hydr-oxyaldehydes.Further work has shown that hydroxyaldehydes inwhich the hydroxy- and the aldehydo-groups are far apart are alsocapable of existing in cyclic forms. Thus t-hydroxynonaldehyde, bythe action of methyl-alcoholic hydrogen chloride, is converted intobeing thus formed. The general reaction may be represented asI I I I 0:C-S . . -? --+ HO-C-.. -C-OH L-o-_Iand either an acyl or an alkyl group may be substituted for thehydrogen atom.,* It is proposed to designate these cgclo-forms ofcarbonyl compounds by the general term “ lactoles,” aldo-lactolesand keto-lactoles being derived from hydroxy-aldehydes andhydroxy-ketones, respectively. The 0-alkyl derivatives of lactolesare called lactolides to express their relation to the glucosides. Thefollowing examples illustrate these new collective terms :acetate. The simpler sugars also >odd be included in thisnomenclature.A method for the reduction of aldehydes and certain ketones toalcohols has been worked out by H. Meerwein and R. Schmidt,26who have studied the conditions necessary for the action of metalalkyloxides on aldehydes.When an aldehyde is treated withaluminium ethoxide in absolute alcoholic solution the followingreactions appear to take place (a1 = 1/3A1) : R*CHO + alOEtR*CH( Oal)*OEt +R*CH,-Oal+ 0:CHMe. The second stage recallsthe decomposition of benzaldehydeacetal into acetaldehyde andbenzyl ethyl ether and the formation of aldehydes and hydro-23 B. Helferich and H. Koster, Ber., 1923, 56, [B], 2088; A , , 1923, i, 1177.24 B. Helferich and F. A. Fries, ibid., 1925, 58, [B], 1246; A., i, 1039.25 B. Helferich, ibid., 1919, 52, 1123.z6 Annnlen, 1926, 444, 221; A., i, 1239.72 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.carbons from ethers. By the use of aluminium ethoxide, yields ofSO--SO% of the amount of alcohol theoretically possible were ob-tained in the course of a few days at the ordinary temperature.Theprocess was successful also with a-unsaturated aldehydes and withthose containing nitro- or halogen radicals, but not with amino- orhydroxy-aldehydes. Those ketones which readily form alkyloxides,e.g., a-diketones, are the only ones easily reduced by this method.It is interesting from a biochemical point of view to note that thosealdehydes and ketones which readily reduce with aluminiumethoxide are easily reduced by phytochemical processes and viceversa. The alkyloxides of calcium and magnesium are withoutreducing action, as is also the less basic calcium ethoxychloride ; onthe other hand, magnesium ethoxychloride is as active as aluminiumethoxide. The paper contains an account of special methods for thepreparation of these reducing agents.An analogous explanation of the action of aluminium ethoxideis suggested by A.Verle~,~' who agrees that the Tischtschenko 28 re-action, SR-CHO = R*CO*O*CH,R, is quite secondary. He suggeststhat the cycle comprises four stages, of which the first results in theformation of a hemi-acetal (I), which passes to the compound (11).This then dissociates, as shown, and the compound (111) by inter-action with alcohol gives CH,R*OH. A similar interchange offunctional groups takes place with ketones and the aluminiumalkyloxides.Me*CHO + CH,R*O*Al(OEt),(111.)The sodium alkyloxides, however, react more rapidly. Methylnonyl ketone, for example, with sodium isopropoxide gives aquantitative yield of undecan-p-ol and acetone.An examination 29 of the utility of aluminium ethoxide as a reagentfor the condensation of aldehydes to esters shows that in its presenceacetaldehyde and heptaldehyde condense at about the same rate andfaster than benzaldehyde, which, itself, is faster than furfuraldehyde.Aluminium ethoxide reacts with certain metallic chlorides, formingcompounds of the type A1C13,3A1( OEt), in the case of aluminium andferric chlorides and HgCl2,2A1( OEt), in the case of mercuric andzinc chlorides.These compounds are much more active in ester27 Bull. Xoc. chim., 1925, [iv], 37, 537, 871; A., i, 783, 1034.28 A., 1907, i, 282.29 W. C. Child and H. Agkins, J . Anzer. Chem. Soc., 1925, 4'7, 798; A., i,632ORGANIC CHEMISTRY.73condensation than the aluminium ethoxide itself. A comparison ofanalogous catalysts in the case of the Condensation of acetaldehydeto ethyl acetate showed that the catalytic activity increased inorder from titanium ethoxide to aluminium ethoxide to aluminiumisopropoxide and aluminium butoxide, the efficiencies of the lasttwo being a)pproximately equal,A synthesis of a-hydroxyketones 30 is based upon the observationthat catalytic reduction converts the grouping -CCl(NO,)- into40- ; thus >CC1*N02+ 6H= :CO+NH,CI+H,O. Using hydro-gen with palladised barium sulphate as catalyst, y-chloro-y-nitro-pentane-pa-diol was converted into pentane-p-ol-y-one and p-chloro-p-nitrobutane-ay-dio1 into butan-p-ol-p-one, which latter appears toClaisen condensation shows that in a number of cases the condens-ation between ketones and esters is the normal one a t low tem-peratures, but a t higher temperatures alcoholysis takes place withdecomposition of the ay-diketone. Diethyl ketone, for example,reacts normally with ethyl acetate a t room temperature in the pre-sence of sodium to give y-methylhexa- pa-dione, MeCOCHMeCOEt,but on warming towards the end of the reaction, hexa-pa-dioneis formed.The explanation suggested is that the excess ofethyl acetate undergoes condensation with methyl ethyl ketone,which is produced by the decomposition of a sodium derivatriveof y-methylhexa-p6-dione according to the following scheme :(MeCOGMe*COEt)Na+SEtOH = NaOEt +C,HS-CO,Et + Me*CO*Et(or perhaps CH3*C02Et +Et.CO*Et).A large number of similarreactions were observed. Calcium hydride,32 when used as a,reagent with ketones, is found to resemble calcium carbide inthat it brings about condensation only with those compoundscontaining the group CO-CH,. On diethyl ketone, for example,it has no appreciable action. With methyl ethyl ketone, it givesone only of the possible isomeric homomesitones, CMeEt:CH*COEt,resembling, in this respect, similar condensing agents.The optimum conditions for the preparation of keten fromacetone are given by C. D. Hurd and W. H. Tallyn 33 as follows :the acetone must be passed through a " pyrex " tube kept a t 700"at the rate of 5 C.C. per minute. In this way, the maximum yield ofsome 40% is obtained. Acetylacetone also undergoes pyrogenicdecomposition into keten, the maximum yield of 16.7 yo beingobtained a t about 630".30 E.Schmidt and A. Ascherl, Ber., 1925, 58, [B], 356 ; A., i, 364.a1 G. T. Morgan, H. D. K. Drew, and C. R. Porter, ibid., p. 333; A., i, 363.32 C. Porlezza and U. Gatti, Gazzetta, 1925, 55, 224; A., i, 788.33 J . Amer. Chern. SOC., 1925, 47, 1427, 1779; A., i, 785, 885.U 74 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,Further contributions to the chemistry of the ketens are con.tributed by H. Staudinger and his co-workers. It was known thatdimethylketen, in an atmosphere of nitrogen or hydrogen and inthe presence of a trace of trimethylamine, gave a colloidal polymeris-ation product. It was discovered34 that in an atmosphere ofcarbon dioxide a t a low temperature addition products are formed ofthe nature 2Di,ICO, ; 3Di,2C02 ; 4Di,3C02.The first of these pro-ducts is a crystalline substance which was shown to be tetramethyl-acetonedicarboxylic anhydride ( p-lieto- EEyy-tetramethylglutaric an-hydride) (I), since on hydrolysis it yields dimethylmalonic andisobutyric acids. This compound was also obtained by thedecomposition of dimethylmalonic anhydride in a sealed tube at100" in the presence of trimethylamine. If the catalyst wereomitted, 1 : 1 : 3 : 3-tetramethylcyclobutane-2 : 4-dione(11) was formed in quantitative yield. The formation of thesesubstances is shown in the following scheme :however,ZMe,C<Eg>O (pressurekheated1 - gentle heat +NMe,+ 2c0,pressure heated(11.) CO*CMe, tAnalogous products were obtained by the interaction of carbondisulphide, and various carbimides, with dimethylketen a t 80" inthe presence of trimethylamine, although these differed in beinghighly polymerised.Amorphous polydimethylketens of highmolecular weight were obtained by keeping dimethylketen, contain-ing a trace of trimethylamine, at -80". The polymerides revert tothe mother-substance when heated at 100-200". A crystallinepolyketen, (C2H20),, has also been prepared which seems to form alink between the colloidal polydimethylketens and the crystallinecyclobutanedione compounds. In order to explain the differencesobserved in the physical properties of the crystalline and thecolloidal additive and polymerisation products of dimethylketen, itis supposed that the crystalline derivatives, e.g., P-keto-aayy-tetra-methylglutaric anhydride (I), contain closed rings, whilst in thecolloidal derivatives, ring closure, for various reasons, is impossibleand these compounds consist of long chains of units of the type.. (CO*CMe2*CO*NR*CO~CMe2*CO*NR*CO*CMe2), ., for example.Acids.The question of the formation of fatty acids from paraffins hasbeen studied by Marcusson,35 who submitted ozokerite to the action34 H. Staudinger, Helv. Chim. Ada, 1926, 8, 306; A., i, 786.35 Chem.-Ztg., 1925, 49, 166; A., i, 349ORGANIC CHEMISTRY. 75of oxygen in the presence of manganese dioxide and fuller's earth.At 125", the action was slow, but a t 150" an acid value of 39 wwattained after 90 hours.The liquid acid fraction consisted of amixture of polymerised unsaturated fatty acids. The solid acidsmelted a t 60-62" with a molecular weight of 384. Convenientmethods for the preparation of acids are given by various authors.S. G. Powell 36 finds that p-chloropropionic acid can be obtained ina yield of more than 50% by adding trimethylenechlorohydrin toconcentrated nitric acid. By the action of hydrogen chloride gason aniline trichloroacetate in the presence of copper, H. W. Doughtyand A. P. Black 37 have obtained a 75% yield of dichloroacetic acid.The optimum conditions for the preparation of n-valeric acid frommagnesium butyl bromide and carbon dioxide have been examined.38A low temperature between 0" and -20" is found essential 39 in orderto obtain a yield of the order of S0-S6~0.At higher temperatures,tributylcarbinol is produced, the yield of n-valeric acid falling tobelow 10% of the theoretical.J. W. E. Glattfield and L. P. Shearman,40 in continuation of theirresearches on " saccharinic acids," describe the pr6paration ofdl-ap-dihydroxyisobutyric acid. The saccharinic acids are definedas those acids which would result from the hydroxyaldehydes ofthe formula C,H,O, which have one hydroxyl group attached toeach carbon atom (except the aldehyde carbon atom), if the oxidationtook place a t the expense of one of the UOH groups-this groupitself becoming reduced to a iCH group. Thus ap-dihydroxyiso-butyric acid is regarded as a saccharinic acid derived from tri-hydroxyisobutaldehyde. The acid is obtained by the action ofsilver oxide on p-chloro-cc-hydroxyisobutyric acid, the yield being32% as compared with 10-15% by other methods.Simpler Unsaturated Patty t4cids.-Acetylenic compounds, onhydrogenation a t the ordinary temperature in the presence ofcolloidal palladium,41 or of are converted almost com-pletely into cis-ethylenic compounds.Among the acetylenic acidsinvestigated, phenylpropiolic acid is converted entirely into iso-cinnamic acid ; tetrolic acid into isocrotonic acid, and acetylene-dicarboxylic acid gives solely maleic acid. The general conclusionis drawn that acids of the type CRiC*CO,H react similarly on36 J . Amer. Chem. SOC., 1924, 46, 2879; A., 1925, i, 228.37 Ibid., 1925, 47, 1091; A., i, 628.38 H.Gilman and H. H. Parkor, ibid., 1924, 46, 2816; A., 1925, i, 228.39 D. Ivanov, Bull. SOC. chim., 1925, [iv], 37, 287; A., i, 503.40 J . Amer. Chem. SOC., 1925, 47, 1742; A,, i, 881 ; compare A., 1921, i, 7 ;41 M. Bourguel, Compt. r e d . , 1926, 180, 1753; A4., i, 883.42 A. GonzAlez, Anal. Fis. Q u h , 1925, 23, 100; A., i, 629.1922, i, 318.C* 76 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.hydrogenation with a metallic catalyst whether R is an aryl or analkyl group.Considerable attention has been devoted t o the problems associ-ated with fumaric and maleic acids. Maleic anhydride has beenobtained to the extent of 99% of the theoretical amount by distillingmaleic acid with 70% of its weight of phosphoric oxide at 100" underreduced pre~sure.~3 The almost quantitative conversion of fumaricor maleic acid into racemic or mesotartaric acid has also beenaccomplished by N.A. hlilas and E. M. Terry,44 using sodiumchlorate as the oxidising agent in the presence of osmium tetroxide.The question of the transmutation of maleic acid into fumaricacid has been examined by E. M. Terry and L. Ei~helberger,4~ whoconsider that the reaction is due to the formation, in the first in-stance, of an additive complex, each carboxyl group of the acidadding one molecule of the catalyst. The effect of this addition isto " activate " the complex a t the *C :C* linking, the active formbeing depicted as an electromeride, *C*C*, which thus becomes freeto assume the trans-configuration.The theory is based on measure-ments of the velocity of conversion of maleic acid in aqueous solutionin the presence of hydrochloric acid or of potassium thiocyanate.No by-products were formed and the velocity was found to be pro-portional t o the concentration of the catalyst and to the secondpower of the initial concentration of the maleic acid. It is thoughtthat the " activation " stage is comparatively slow, and that it isthe velocity of this that is actually measured. The action ofbromine on these acids in aqueous solution, which was found toresult in the formation of 78% of dibromosuccinate and 10% ofisodibromosuccinate, is similarly explained. H. Meerwein andJ. Weber46 also consider that the capacity of catalysts to causethe transformation of these stereoisomeric ethylenic compoundsdepends on their power of activating the double bond.Allsubstances, therefore, which are capable of addition a t thedouble bond should catalytically accelerate the transformation.Insupport of this view, it is shown that metallic potassium,which is known to have the power of addition at the ethyleniclinking, converts methyl maleate into methyl fumarate in thepresence of dry ether.Some interesting observations on inversion phenomena, coupledwith a discussion on the bearing of the results on the stereochemistry43 E. M. Terry and L. Eichelberger, J . Amer. Chem. Soc., 1925, 47, 1067;A., i, 631.O4 Ibid., p. 1412; A., i, 780.45 Ibid., pp. 1402, 1067; A., i, 780, 631.46 Ber., 1925, 58, [B], 1266; A., i, 1038.+ ORGANIC CHEMISTRY. 77of the orp-diols, sugars, etc., is contributed by R.Kuhn and F. Ebe1.47When hypochlorous acid reacts with maleic acid the sole productis a chloromalic acid I, m. p. 145", but with fumaric acid the reactionis not homogeneous, a chloromalic acid 11, m. p. 153.5", being one onlyof the products. These acids differ greatly in the ease of replace-ment of halogen by the hydroxy-group, the half-periods underidentical conditionsfor chloromalic acids I and I1 being 18and 200,000minutes, respectively.Loss of hydrogen chloride converts chloromalic acid I into afumarylglycidic acid, which was resolved into its optical antipodesand is therefore regarded as trans-oxidoethylene-orp-dicarboxylicacid (111).Chloromalic acid I1 yields a cis-oxidoethylene-ap-dicarboxylic acid (IV), which resisted all attempts at resolution.The trans-acid (111) on treatment with boiling water gave a mixtureof r-tartaric acid (37 yo) and mesotartaric acid (63y0), whilst thecis-acid (IV) gave only r-tartaric acid, the homogeneous reaction inthis case being comparable with that between hypochlorous acidand maleic acid. It thus appears that cis-compounds, in additivereactions, yield one derivative only, while trans-compounds give amixed product. These and other observations are included in thefollowing scheme,trans - oxidoe t hylene -up -diearbox ylic acid (111)Chloromalic acid I Of Hzo -+Chloromalic acid I1 action Of Hzo +k I"J.cis-oxidoethylene-up-dicarboxylic acid (11')T- and meso-tartaricacidsr- and rneso-tartaric acidsmeso-tartaric acid aloneT-tartaric acid alonewhich shows that it is possible to convert the cis-acid (IV) eitherdirectly into r-tartaric acid or indirectly, through chloromalic acid11, into mesotartaric acid. The claim that the conversion of cis-oxidoethylenedicarboxylic acid into r-tartaric acid is the firstrecorded instance of quantitative transfission of a ring system isdisputed by 5.B o e ~ e k e n . ~ ~Further light has been thrown on the double linking in suchgeometrical isomerides as fumaric and maleic acids by the applic-ation of the concept of the p a r a ~ h o r . ~ ~ This quantity, which involvessurface tension and density, can be expressed 50 as a simple4 7 Ber., 1925, 58, [B], 919, 1447; A,, i, 780, 1237.48 l b i d ., 1470; A., i, 1237.** S. Sudgen and H. Whittaker, J., 1925, 127, 1868.6o Ann, Report, 1924, p. 878 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.additive function of cert,ain atomic and structural constants. Ifthe values of these constants are known, the theoretical parachorcan be calculated. It has further been shown 51 that the parachorenables a distinction to be drawn between the two types of doublebonds predicted by the octet theory of valency, vix., the ordinarynon-polar double bond, which consists of two co-valencies, and thesemipolar double bond, made up of one co-valency and one electro-valency. The presence of one of the former is found to add 23-2 unitsto the parachor, whilst the latter lowers the parachor by 1.6 units.Langmuir has assumed that carbon-carbon double bonds are non-polar, and Sugden 52 has suggested that there must be free rotationround a semi-polar double bond, so that it would be expected thatunsaturated compounds exhibiting geometrical isomerism wouldhave a linking of the non-polar type.Measurements of theparachors of cis- and tra,ns-unsaturated esters are now recorded,and in every case the experimental value agrees closely with thetheoretical value, calculated on the assumption that a non-polardouble bond is present. The investigation included the esters offumaric acid and maleic acid, mesaconic and citraconic acids, andcinnamic and allocinnamic acids.It was suggested in a previous Report 63 that an X-ray study offumaric and maleic acids wight afford valuable information regard-ing the isomerism exhibited by this series of acids. The preliminaryresults of such an investigation are now rep0rted.5~Higher Fatty Acids and their Derivatives.-A very large amountof work has been carried out in this field during the year.Theseparation of the fatty acid components of the natural oils and fatshas been studied by various authors. The fractional distillation ofthe methyl or ethyl esters of the separated fatty acids has beenshown 55 to be a very satisfactory method for the separation of themixed fatty acids, provided that in certain cases the solid and liquidacids are separately esterified and other precautions talken.Theseesters form the basis of a new p r o c e d ~ r e , ~ ~ by which the position ofthe ethylenic linking in acids of the oleic series can be determined.Methods previously employed are complicated, and open to theobjection that migration of the ethylenic linking is not excluded,whilst the products obtained are complex mixtures from which itis difficult to deduce a structural formula. It was found that51 Sudgen, Reed, and Wilkins, J., 1925, 127, 1525.52 J., 1923, 123, 1864.63 Ann. Report, 1923, p. 69.54 K. Yardley, J., 1925, 127, 2207.5 5 E. F. Armstrong, J. Allan, and C. W. Moore, J. Xoc. Chem. Ind., 1925,56 E. F. Armstrong and T. P. Hilditch, ibid., p. 43T; A., i, 355.44, 631.; A., i, 353ORGANIC CHEMISTRY. 79oxidation of the methyl or ethyl esters with permanganate in hotacetone or acetic acid solution leads definitely to the production ofthe monobasic and dibasic acids corresponding to the position of theethylenic linking, in very high yield, viz., about 80% of the theoreticalyield of the dibasic, and rather less of the monobasic, acid.Ethyloleate gave azelaic acid amounting to 95% and nonoic acid 59% ofthe theoretical.Extending these methods to the constituents of whale oil fromSouth Georgia, the authors show57 that the unsaturated acidspresent include myristolenic acids C14 (1-1-5%), chiefly Ac-tetra-decenoic acid mixed with a small quantity of the Av- or Ae-acid;palmitolenic acid C,, (15 yo), identified as entirely Ac-hexadecenoicacid; an oleic acid C18, Ac-octadecenoic acid, with a very smallproportion of the A*-derivative.These are of the semi-drying ormoderately unsaturated type. In addition, however, some acidswere isolated which appear to be in a class apart. They fall intothe C,, and C,, series, and are so highly unsaturated that the averagetotal unsaturation, expressed in terms of ethylenic linking, amountsto four or five of the latter. In these acids, as in the others isolated,no double bonds appear nearer the carboxyl group than the A9:lo-position, an observation which may possess some biochemicalsignificance.Chinese wood oil is found to contain 58 up to 90% of the glycerideof a-elzeostearic acid. This, CH,*[ CH,],*[ CH:CH],*[CH2I7*C0,H,was converted under the action of ultra-violet rays into the p-derivative.Elzeostearic acid has been considered an isomeride oflinoleic acid, but a study of the molecular refractivities of the a- and6-acids, their glycerides and the ct-ethyl ester shows that in all prob-ability three conjugated double bonds are present. The formulagiven above is therefore suggested for these acids, and the highdegree of unsaturation has been confirmed by hydrogenation in thepresence of a nickel catalyst.The glycerides of cacao fat have been shown 59 to consist of 55%of glyceryl a-palmitate py-dioleate, 20 yo of glyceryl p-palmitateay-distearate, 25 yo of glyceryl a@-distearate y-oleate with smallquantities of glyceryl p-palmitate ay-distearate and tristearin.G. T. Morgan and A. R. Bowen60 also find that no higher acidE.F. Armstrodg and T. P. Hilditch, J . SOC. Chem., Ind., 1925, 44,58 J. Bijeseken and (Mlle.) H. J. Ravenswaay, Rec. trav. chim., 1925, 44See also Proc. K . Akad. Wetensch. Amsterdam, 1925,28, 386 ;59 K. Amberger and J. Bauch, 2. Unters. Nahr. Genussm., 1924, 48, 371;6a J . SOC. Chem. Ind., 1924, 43, 346; A., 1925, i, 114.p. 180T; A., i, 778.241 ; A., i, 507.A., i, 1129.A., 1925, i, 11480 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.than stearic acid is contained in cacao fat, so that it is useless as asource of eicosanoic acid. They note that stearic and eicosanoicacids form a compound Cl,H360,,C,oHm0, and that a mixture con-taining 50% of each is not separable by fractional crystallisation.The occurrence of a highly unsaturated acid, C2,H3,02, in variousalgs has been recorded.61 The acid gives a bromo-derivative,C,,H,,O,Br,, and on reduction yields behenic acid.Successful attempts to develop methods which could be appliedto the synthesis of the naturally occurring unsaturated fatty acidsare reported by G.M. and R. Robinson.62 Concentrating first onthe synthesis of oleic acid, it was found that this acid had previouslybeen obtained from 10-ketostearic acid, CH,=[CH,],*CO*[CH,],*CO,H,by reduction of the CO group followed by conversion to 10-iodo-stearic acid and treatment of this with alcoholic potassium hydroxide.The synthesis of 10-ketostearic acid was achieved by condensing ethylsodio-2-acetylnonoate and 9-carbethoxynonyl chloride. The re-sulting ester, CH3*[CH,],oCAc(C02E~)*CO~[CH2]8~~~2~~, on hydro-lysis, yielded 10-ketostearic acid (m.p. 83"), which was converted,by the methods given above, into oleic acid identical with a purespecimen from olive oil supplied by A. Lapworth, who 63 has madea careful study of the isolation of pure oleic acid and the propertiesof its salts. The synthesis proves that the double bond in oleic acidis in the A9:lO or AIO:ll position. To eliminate the latter alternative,attempts are in progress to synthesise shearolic acid, since this canbe reduced by zinc and hydrochloric acid, in the presence of titanouschloride, to oleic acid, a reaction which indicates that oleic acidpossesses the cis-configuration. The method of synthesis was alsosuccessfully employed in the case of lactarinic acid, which wasoriginally isolated by Bougault and Chavaux 64 from various speciesof fungi and shown by them to be 6-ketostearic acid.The synthesishas now been accomplished by condensation of ethyl 2-acetyl-n-tri-decoate and 5-carbethoxyvaleryl chloride, which gives the esterCH3*[CH,],o*CAc(C02Et)*CO*[CH,]4~C0,Et, from which, by gradu-ated hydrolysis, lactarinic acid, CH,*[CH,], 1*CO*[CN,]4G0,H,was obtained identical with the natural product. 4-Ketopalmiticacid, Cl6H30O3, also was prepared. Further development of thesemethods will be awaited with interest.This work has led to an accurate estimation of the highersaturated acids in specimens of oleic acid.65M. Tsujimoto, Chem. Umchau, 1925, 32, 125; A., i, 778.6a J., 1925, 127, 175.63 A.Lapworth, L. K. Pearson, and E. M. Mottram, Biochem. J., 1925, 19,O4 Compt. rend., 1911, 153, 572, 880.65 A. Lapworth and E. M. Mottram, J., 1925, 127, 1629.7; A., i, 355ORGANIC CHEMISTRY. 81The synthesis of arachidic acid and some other long-chain com-pounds 66 has revealed the fact that the melting points of methyland ethyl arachidate and of eicosyl alcohol previously observedare from 7" to 10" higher than the true values now recorded. Theregular rise in melting point in the even series of long-chain com-pounds is important, since it has been shown that from this rise,and other regularities, a crystal structure can be predicted 6' whichhas been shown by X-ray analysis to be correct.68 The synthesisinvolved a modification of Bouveault and Blanc's method : Ethylstearate gave octadecyl alcohol, and ethyl arachidate gave eicosylalcohol ; then, for example, octadecyl iodide was converted intomono-octadecylmalonic acid, which on heating gave arachidic acid.By a modification of the Krafft method, a number of the highermethyl ketones have been obtained,G9 among which methyl n-octs-decyl ketone and methyl n-nonadecyl ketone are new.Starting,for example, with erucic acid (I), behenic acid (11) was prepared byhydrogenation in the presence of palladium. From this, methyln-heneicosyl ketone (111) was formed, which on oxidation gaveheneicosoic acid (IV). The barium salt of this, distilled with bariumacetate, gave methyl n-eicosyl ketone (V).(IV.) C,(;H*,*CO,H -+ C,oH4,*CO*CH, (v.)The acid (111) proved to be identical with the heneicosoic acidisolated by Le Sueur and Withers 70 and isomeric, therefore, with thecluytinic acid of Tutin and Clewer.'l L.J. Simon,', in the course ofa series of investigations on the oxidation of Unsaturated fatty acidsby a mixture of sulphuric and chromic acids, finds that completeoxidation of the carbon takes place only if the unsaturated linkingis in a terminal position. This applies both to dibasic and to mono-basic acids. Ay-Pentenoic acid is an exception, and undecenoic acidreacts as though the CH,: group were not present, which observationseems to call for a revision of the structure assigned to this acid.The deficiency in the carbon completely oxidised amounts to nearly2 atoms per molecule in the case of straight-chain acids, of whichstearic, oleic, elaidic, tariric, taroleic, ketotariric, and others were6 6 N.K. Adam and J. W. W. Dyer, J., 1925, 127, 70.67 N. K. Adam, PTOC. Roy. Xoc., 1922, A , 101, 528.6* A. Miiller and G. Shearer, J., 1923, 123, 2043, 3152, 3156.69 G. T. Morgan and E. Holmes, J . SOC. Chem. Ind., 1925, 44, 1 0 8 ~ , 4 9 1 ~ .7O J., 1915, 107, 736.7l J., 1914, 105, 559.72 C q t . rend., 1925, 180, 833, 1405; A., i, 505, 77882 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.studied. In derivatives such as the ethyl esters and glycerides thereis a deficiency of nearly 2 carbon atoms for every carbon chain in themolecule.The difficult question of the drying of oils continues to producea number of reports.P. Slansky73 observes that the oxide andcarbonate of lead or calcium have a far greater effect on the dryingof linseed oil than the sulphate. He explains this by a developmentof the hypothesis of Harkins and Langmcir on the polar distributionof the molecules at a liquid surface, whereby the basic catalysts, invirtue of their affinity for the carboxyl groups of the glyceride endof the molecule, direct these groups inward, leaving the unsaturatedgroups outward, so that these more readily undergo oxidation. Anexhaustive study of the autoxidation of linseed oil ’* has confirmedthe accuracy of the pioneer work of Mulder on “linoxyn,” forwhich the formula C57H96020 is confirmed. This is the mosthighly autoxidised product obtainable by Mulder’s method andrepresents 70--80% of the dried oil.Attempts to separate thissubstance into two or more components failed, and its individualityis postulated. Experiments on the influence of light and temper-ature on the oxidation seem to show that the temperature is all-important and that the action of light is mainly due to a heatingeffect .75As to the mechanism of the “ drying ” of fatty oils by driers, A.Eibner and F. Pallauf 76 conclude that the autocatalytic agent isthe aldehyde peroxide primarily formed. The driers are stated, notonly to catalyse the formation of such peroxides, but also to take adirect part in the transference of oxygen.Monosaccharides.The mixture of sugars (formose) obtained by the action ofalkaline condensing agents on formaldehyde has been shown 77to contain sorbose in addition to dl-fructose and a ketopentose.The condensation is said to take place with great ease whenformaldehyde is heated in dilute solution under a pressure of 2atmospheres inthe presence of rnagne~ia.’~ Methyl alcohol and formicacid are first produced and the magnesium oxide dissolves.Theformation of sugars then begins and is complete in a few minutes.Ketoses are formed in this way, but not aldoses; dihydroxy-acetone and a pentose also were recognised among the products.73 Chem. Umschau, 1924, 31, 281; A., 1925, i, 114.74 G. W. Ellis, J . SOC. Chem. Ind., 1925, 44, 401, 4 6 9 ~ .7 5 Idem, ibid., p. 4 7 2 ~ .76 Chem. Umschau, 1925,32, 81 ; A., i, 777.7 7 W.Kuster and F. Schoder, 2. physioi. Chem., 1924, 141, 110; A., 1925,78H. Schmalfuss and K, Kalle, Ber., 1924, 57, [B], 2101; A., 1925, i, 116.i, 366ORGANIC CHEMISTRY. 83In the Report of last year it was stated 79 that, of the aldoses sofar constitutionally examined with respect to their internal oxiderings, galactose and mannose would appear to exist normally as1 : 5- or amylene oxides. Glucose, to which a 1 : 4- or butyleneoxide structure is generally ascribed, remained in doubt, but " shouldit be drawn into the analogy with galactose and mannose, then thefortuitous terminology of a y-sugar will acquire a new and generalmeaning in that such a compound will be one that gives rise on theoxidation of its tetramethyl derivative to a y-lactone as understoodin the ordinary sense," ie., as one having its lactone ring in the1 : 4-position.The important observation is now reported byW. N. Haworth 8o that the normal tetramethyl glucose yields onOxidation a S- and not a y-lactone, whilst the latter is obtained fromthe y-sugar. To glucose, therefore, is assigned the 1 : &oxide ringstructure, and it may now be said that all aldoses exist normally inthe amylene oxide form. This change in the formulation of glucose,if accepted, will necessitate alteration in t'he oxide ring linking in thecase of a large number of structural formulz assigned to glucosederivatives and carbohydrates based upon glucose.The above, with other observations recently recorded, emphasisesthe necessity for obtaining independent evidence for the internalstructure of each individual sugar or sugar derivative.Examinationof both normal and y-type of compounds has shown that the same1 : &oxide linking is present in tetramethyl y-fructose,sl thenormal sugars trimethyl xylose and tetramethyl galactose and prob-ably tetramethyl mannose. The y-derivatives of galactose, on theother hand, are of the 1 : 4-oxide structure.In extension of t<hese researches to the pentoses, it has now beenshown 82 that the normal stable derivatives of arabinose are of theamylene-oxidic type (11) and in all probability the same structureapplies to the free pentose (I).The evidence was obtained by oxidation of the trimethyl ambinose79 Ann. Report, 1924, p.73.80 Nature, 1925, 116, 430; A . , i, 1133; J., 1926, 89.81 W. N. Hsworth and W. H. Linnell, J . , 1923, 123, 294.** E. L. Hirst and G. J. Robertson, J . , 1925, 127, 35884 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.(III), which gave, in quantitative yield, trimethyl glutaric acid (IV).The results of the critical study of the methylation process carriedout during the past few years show that the oxide linking of a normalmethylaldoside remains unchanged during methylation, so that itmay be argued that the unsubstituted a- and p-methylarabinosides,from which the fully methylated derivatives are prepared, will alsocontain the same type of linking. A new derivative, trimethylp-methylarabinoside, m. p. 46--48O, was shown to have the sametype of oxide linking as the corresponding a-derivative discoveredby Purdie and Rose.83 These derivatives are shown to be inter-convertible forms of normal a- and p-trimethyl methylarabinoside.The presence of isomerides with a different oxide ring structurewas also indicated.Derivatives of Z-arabinose previously known are all dextro-rotatory.A new series of laevorotatory compounds has beenobtained which have a different oxide ring structure and belongto the class of y-sugars. Their synthesis was achieved 84 by con-densing Z-arabinose with the methyl-alcoholic hydrogen chloridereagent a t 18" instead of 100". A liquid y-methylarabinoside([.ID -71.3") results, which is very unstable to potassium pqrman-ganate and is readily hydrolysed by dilute acids.On methylation,and hydrolysis with 0.25 % acid, trimethyl y-arabinose was obtained,[a]D-396", the structure of which was determined by its behaviouron oxidation with nitric acid, which gave the lactone of a, tri-methoxyhydroxyvaleric acid and dimethoxyhydroxyglutaric acid,CO,H*CH( OMe)*CH( OMe)*CH( OH)*CO,H.These results, coupled with a consideration of Hudson's rule, make a1 : 3- or a 1 : 4-oxide structure certain and the 1 : 4 is preferred, asthe existence of a propylene oxide sugar has hitherto not beensubstantiated. It would seem to be established, therefore, that inthe pentose series the y-sugars also belong to the butylene oxidetype.A study 85 of the isomeric tetramethyl galactonolactones andtrimethyl arabonolactones still in progress makes i t probable thatboth in the case of galactose and arabinose the original sugars, andthe lactones and amides prepared from them, are mixtures of the1 : 5- and 1 : 4-isomerides.It is pointed out that, whilst galactoseand arabinose show such a marked tendency to react in both forms,the 1 : 5 being the normal, glucose and xylose under the sameconditions produce only one form. The relationship between theformule of the pairs of sugars is suggestive in this connexion.83 J., 1906, 89, 1204.s4 S. Baker and W. N. Haworth, J., 1925, 127, 365.8 5 J. Pryde, E. L. Hirst, and R. W. Humphreys, ibid., p. 348ORGANIC CHEMISTRY. 85Galactose. A rctbinosc. Glucose. x yzosc.H OHHO H H OHH O I H HIOH HO H 1 i IT OHHO H H OH11 OHThe structure assigned to the simpler methylated sugars whichare utilised as reference compounds in the constitutional study ofcarbohydrates should obviously be reviewed from time to timein the light of new developments.Of these reference corn-pounds, 2 : 3 : 5(or 2 : 3 : 4)so-trimethyl glucose has been ex-amined 86 from this point of view. Its structure forms the keyto the constitution of maltose and p-glucosan, and is of importancein connexion with the chemistry of starch. Part of the evidence onwhich its existing constitution has been based rested on the oxidationreactions with nitric acid, which experience has shown to be notentirely trustworthy.The new synthesis, however, which was designed to produce amethylated glucose with unsubstituted hydroxyl groups definitelyin the terminal positions 1 and 6, entirely confirms the structurepreviously employed.Evidence of the correctness of the consti-tution assigned to p-glucosan was also obtained. Triacetylglucosan (I) was converted into a triacetyl dibromoglucose byKarrer's process, identical with that obtainable from penta-acetylglucose and therefore having formula (11). The succeeding stagesmay be represented structurally as follows :r9H-i rCHBr r-CH-OMegH*OMe $H*OMeCH,Br CH,*OH(VI) proved identical with the trimethyl B-methylglucosideobtained directly from the trimethyl glucose which was the object ofcriticism. P-Glucosan was converted into trimethyl glucose asprevioudy recorded. The sugar, on acetylation, gave trimethylglucose diacetate, which, with hydrogen bromide, gave trimethyl86 J.C. Irvine and J. W. H. Oldham, aid., p. 272986 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.acetyl glucose bromohydrin, and this by the action of sodiummethoxide was converted into trimethyl p-methylglucoside identicalwith (VI) above. The formula for p-glucosan employed in (I) aboveis thus verified.A new synthesis of alkylglucosides has been achieved by E.P~CSU,~' who finds that a mixture of CC- and p-methylglucosides isobtained when d-glucosedibenzylmercaptal is heated with a methyl-alcoholic solution of mercuric chloride. The mercaptal can alsobe converted88 by methyl ethyl ketone in the presence of coppersulphate into a 76-isobutylidene ether, and this compound on suit-able treatment yields monomethyl-d-glucosedibenzylmercaptal.The latter, by the action of the ethyl alcohol and mercuric chloride,gives the ethyl ether of monomethyl d-glucose, from which4-methyl d-glucose, m.p. 156", is obtained. The constitution ofthis is deduced from its non-identity with 2-, 3-, or 6-methyl glucose.Trimethylglucosedibenzylmercaptal, by treatment with the methyl-alcoholic mercuric chloride reagent followed by hydrolysis, gave4 : 5 : 6-trimethyl d-glucose JI). This represents a case of the presenceof a propylene oxide ring, evidence for which was found in itsability to condense with acetone and to give a phenylhydrazone.r-o- 7(I.) CH( OH)CH( OH)*CH*CH( OMe)*CH( OMe)*CH,* 3Me.A further study 89 of the acetone sugars has shown that an amino-hexose can be obtained from galactose diisopropylidene ether bythe action of liquid ammonia followed by the removal of the iso-propylidene groups, although the position of the amino-group hasnot been definitely determined.Diiso-propylidene mannose 90 is similarly convertedinto diisoprop ylideiiemannos ylamine (I1 ;R = NH,). This compound, on heating,is transformed into a secondary amine,HQ*'>CMe, (C,,H,,O,),NH, the existence of which,coupled with the observation that dimethyl-amine reacts towards diisopropylidene mannose in the same way asammonia, makes it improbable that the primary amine containsthe basic group in an 1 : 4-bridge. The constitution of diisopropyl-idene mannose is now represented by the formula (11) above (R= OH)instead of that previously given.g1Under the action of triphenylmethyl chloride in anhydrous pyr-87 Ber., 1925, 58, [B], 509; A ., i, 515.8 8 Idem, ibid., p. 1455; A., i, 1242.89 K. Freudenberg and A. Doser, ibid., p. 294; A., i, 366.9" I<. Freuderiberg and A. Wolf, ibid., p. 300; R., i, 367.91 A., 1923, i, 1179.O*CH 6cMe2<0.()H IH.C---'(11.1 H,C*ORGANIC CHEMISTRY. 87idine, reactive hydrogen atoms present in the sugars and certainhydroxy- and amino-acids are replaced by the triphenylmethylresidue.92 d-Glucose, for example, yields triphenylmethyl-a-d-glucose, in which the triphenylmethyl group is probably attached a tthe 6-carbon atom ; ethyl p-hydroxypropionate gives ethyl p-tri-phenylmethyloxypropionate, and carbamide yields bistriphenyl-methylcarbamide, a compound remarkably resistant to the actionof alkali hydroxide.Triacetylglucal (I) is converted on boiling with water into adiacetyl derivative (11).This compound combines with two atomsof bromine, but on treatment with hydrogen in the presence ofplatinum black it takes up four atoms of hydrogen. It has re-mained uncertain whether this diacetyl compound was a directderivative of glucal or an isomeric conversion product (see below).M. Bergman,g3 who had advanced the view that a rearrangementof the glucal nucleus takes place on boiling with water and hadtherefore used the term diacetyl-9-glucal for the diacetate formed,now advances further evidence in support of this view.It is foundthat with palladium-black diacetyl-+glucal forms first a crystallinedihydro-+glucal diacetate (111), which on further reducttion givesa d-hexane-ct&C-tetrol diacetate. Both diacetyl-+-glucal and thedihydro-derivative (111) react with ethyl orthoformate to give ethylcycloacetals (IV and V). Compound (V) on hydrolysis yields theQHO QHOEti QHOEtip 2 EH I QH2 IQH2 QH ? (jH, ?QHO RHQH HY-J HY-J!ElAcgvHq HY*OH HV*OHHV*OAc HC;*OAc HY*OAc HY*OH H(i*OAcCH,*OAc CH,*OAc CH,*OAc CH,-OH CH,*OAc(1.1 (11.) (111.) (IV.1 (V.1same a-2 : 3-bisdeoxyglucose ethyl cycloacetal as is obtained by thereduction of (IV) with palladium-black.GZucosides.-Glycerol glucoside, first obtained by E. Fischer D4by saturating a glycerol solution of glucose with hydrogen chloride,can be obtained more easily by limiting the acid concentration to0.25% and heating to The constitution of this compoundwas established by methylation, which gave a hexamethyl glycerolglucoside. On hydrolysis, this gave 2 : 3 : 5 : 6-tetramethyl glucosetogether with a dimethyl glycerol identified as ap-dimethoxy-92 B.Helferich, L. Moog, and A. Jiinger, Ber., 1925, 58, [B], 872; A., i, 790.93 Annalen, 1925, 443, 238; A., i, 887.94 Ber., 1894, 27, 2483.95 H. S. Gilchrisf and C. B. Purvis, J., 1925, 127, 273688 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.y-hydroxypropane. The parent glucoside is therefore representedby the formulaCH2( OH)*CH( OH) *CH*CH( OH)*CH( OH) *CH*O*CH,*CH( OH)*CH2*OH.L 0-JDisaccharides.A study of the fission of y-methylfructoside by invertase 96includes the suggestion that the term y-sugar is confusing, now thata- and p-stereoisomeric forms of these labile sugars are known, andthe prefix ~ ( ~ T c ~ o s ) is proposed.It is found that both yeast-invertase and taka-invertase are active towards h-methylfructosidesand therefore the suggestion of Kuhng7 that the fructose portionof sucrose is attacked by the former enzyme and the glucose by thelatter cannot be maintained. Hudson has calculated the value[a]= $- 17" for the fructose component of sucrose, but this cannotbe the unknown a-fructose, the specific rotation of which, calculatedfrom its relationship to d-arabinose, is not in agreement. Thedifficulty is removed by regarding the fructose component as P-h-fructose, and the constitution of sucrose is considered to be bestexpressed by the formulaE.Fischer and K. Delbriick98 in 1909 obtained an iso-trehalose by the action of phosphorus pentoxide on a chloroformsolution of tetra-acetyl glucose. This product differed from trehal-ose in being laevorotatory, and according to a calculation of Hudson 99it is the pp-form of trehalose, the natural sugar being the acc-form.Up to now, methods have been wanting for the direct synthesis ofdisaccharides of the a-series, and as trehalose represents the extremecase of the a-type, experiments on its synthesis have been initiatedwith a view to discover methods which would lead to a trustworthymethod of synthesis for disaccharides of the type of sucrose andmaltose.The method adopted consisted in the action of hydrogenchloride on tetra-acetyl glucose at various temperatures and in thepresence, or otherwise, of dehydrating agents and catalysts. Withthe majority of these agents very little progress was made, but inthe case of zinc chloride a t 140" a 50% yield of a disaccharide wasobtained. The octamethyl ether of this product with [a]:' + 82.8'differed entirely from the octamethyl ether of trehalose, [a]:@ +Q6 H. H. SchIubach and G. Rauchalles, Ber., 1925,58, [B], 1842; A., i, 1243.O 7 A., 1923, i, 1033.s8 J. Amer. Chem. SOC., 1916, 38, 1571.e8 Ber., 1909, 42, 2776.H. H. SchlubachandK Maurer, Ber., 1925, 58, [B], 1178; A., i, 888ORGANIC CHEMISTRP. 89199.8", prepared for comparison, and whilst, on hydrolysis, the latterderivative gave a 73% yield of 2 : 3 : 5 : 6-tetramethyl glucose, theether of the new sugar gave only 17.5%. The rotation of the newsaccharide agrees fairly well with the value calculated by Hudsonfor ccp-trehalose ([~t]:? + 70"), but there is not a t present sufficientevidence to decide its identity.on the galactosido-glucose first prepared in 1902 by E.Fischer and E. F. Armstrong:by the action of sodium alkyloxide on a mixture of dextrose andacetochlorogalactose. The product has generally been regarded asidentical with melibiose and the synthesis would thus stand as theearliest accomplished among the &saccharides. The new investig-ation shows that the octamethyl derivative of the synthetic productis not identical with melibiose octamethyl ether, which has now beenprepared for the first time and proved to be, unlike the ether of thesynthetic product, crystalline, with m.p. 48.5". The physical con-stants of the synthetic octamethyl ether agree closely with those oflactose octamethyl ether and on hydrolysis 2 : 3 : 4 : 6-tetramethylgalactose is obtained, which shows that the galactose components inlactose and in the galactosidoglucose are identical. On the otherhand, the glucose component of the latter, isolated as a trimethylglucose, was not the same as that from lactose, so that the identityof the new sugar with lactose cannot be maintained.Pol ysacchar ides.By the oxidation of amylodextrin with bromine in the presence ofbarium carbonate, V.Syniewski 4 has obtained an amylodextrinicacid, c216H3480198, which has reducing properties equivalent to23.24% of maltose. The barium and lead salts indicate that thenew acid has a basicity of twelve, a result which is also in agreementwith the composition found for the hydrazide. The followingformula is assigned to the acid,Work on similar lines has been carried outr-0-1 [(C18)(>*(C6)-O-CH*[CH*OH],*CH*CH(OH)*C0,H)3]4this being based upon the author's formulation of amylodextrin,C216H3,201,, (which is formed from starch, C216H3600180, by theaddition of 6 molecules of water), fist suggested5 in 1902, vix.,[(c18){ > (C12))3]4, where (318 represents an amylogen residue, C,,maltose, and > union with the carbonyl linking.From this formulait would appear that glycuronic acid residues should be present in theH. H. Schlubach and W. Rauchenberger, Ber., 1925,58, [B], 1184;A., i,888.Ber., 1902, 35, 3146.Ibid., 1902, 324, 213; A . , 1903, i, 69.Annalen, 1925, 441, 277; A . , i, 36990 ANNUAL REPORTS ON TRE PROGRESS OF CHEMISTRY.new acid equivalent to 34.6% of glycuronic anhydride. Experimentshowed that 5.2% of furfural was actually obtained, which corre-sponds to 34% of glycuronic anhydride. This observation leadsto the suggestion that the glycuronic acid of the animal body isderived, not from the oxidation of the primary alcoholic group ofdextrose, but by the hydrolysis of an oxidation product of glycogensimilar to amylodextrinic acid.The author’s formula for starch, given in condensed form above,is based upon a union of four amylogen complexes.Amylogen isrepresented as(c6)*a*(c,)*y*(C6>@ 12(c6)*a*(c6)*~*(c6)(C6)*a’(Cfj)*~*(C6)the letters a, p, and y indicating linkings of these orders, and it waspredicted that under exclusively a-carbonyl hydrolysis a non-reducing “ limit dextrin I ” would be formed. V. Syniewski e, hasnow discovered an almost purely a-carbonyl-hydrolytic agent in thediastatic enzyme of ungerminated barley. Under its action amylo-dextrin is rapidly converted into maltose (64%) and the new “ limitdextrin I,” C72H132066. This substance does not reduce Fehling’ssolution and gives a blue colour with iodine, this property differentia-ting it from the products of the action of malt diastase on amylo-dextrin. With malt extract, it undergoes p-hydrolysis, giving thereducing “ limit dextrin I ” identical with the achroodextrin ofLintner.Acetylation shows that forty-eight hydroxyl groups enterinto reaction and considerations based upon the author’s formula foramylodextrin lead to the conclusion that six of the remaining oxygenatoms are present in a-carbonyl linkings and twelve in p-carbonyllinkings. Its formation is expressed by the equation :c216H3720186 $- 12H20 = 12C12H22011.+C72H132066~The polyamyloses isolated by Pringsheim and others from potatostarch have been classified by him (“ Die Polysaccharide,” 1923,p. 167) into gn a- and a (3-series. The former includes a hexa-amylose, [(C6H100,)2]3, and a tetra-amylose, [ (C6H1005)2]2 ; thelatter, a hexa-amylose, [(C6H1005)3]2, and a friamylose, (C6H1005)3.Although the letters a- and p- were not intended to have any con-stitutional significance, yet by a coincidence a- hexa-amylose isfound to belong to the a- series and a@-hexa-amylose, which isregarded by Ling and Nanji as identical with Baker’s a-nmylodextrin,falls among the members of the p-series.’ The suggestion of Pring-sheim is that starch and the amyloses consist of basal units (shownAnnalen, 1925, 441, 285.J., 1923, 123, 2669ORGANIC CHEMISTRY. 91in round brackets above) polymerised to the varying degrees shownwithin the angular brackets, the units being held together by sub-sidiary valencies. R. Kuhn 8 considers that neither the poly-amyloses nor the hexosans can be considered with certainty to bethe fundamental units of the starch molecule.The lengthy paperin which the arguments are advanced contains the observation thatby the action of maltase-free amylase (from green and kilned malt)on starch or amylose the whole of the maltose formed is of thep-form. Taka-diastase and pancreatic amylase, however, yield amaltose the mutarotation graph of which indicates the initial form-ation of the a-form of maltose. The amylases may thus be dividedinto a- and p-groups according to the form of maltose initiallyproduced.The use of biological methods under exactly controlled conditionshas led, a t the hands of Ling and Nanji,g to definite advances in ourknowledge of starch.These authors find that some of the starches,e. g . , potato starch, consist entirely of amylose (the inner portionof the granule) and arnylopectin (the outer portion) and that, if so,these constituents are present invariably in the proportions amylose66-6%, amylopectin 3303%. This ratio of 2 : 1 is also found tosubsist in the case of starches, e.g., rice starch, which do not consistentirely of amylose and amylopectin. They are able to explain thefailure of other workers, e.g., Pringsheirn and Wolfsohn,lO to obtainanything approaching such a high proportion of amylose by theresults of a histological investigation of the starch granules, whichshowed that, whilst some 25% of the " amylose " exists as a crystal-loid phase, forming a core round the hilum of the granule which isreadily extracted by water and dilute acids, the remainder is presentin a colloidal phase, dispersed uniformly through the amylopectinlayers.This portion is so strongly adsorbed as to resist extraction.Treatment with barley diastase a t 50°, however, converts the amyloseinto maltose and the amylopectin into ap-hexa-amylose.Certain starches, however, notably those of barley, wheat and rice,when treated with barley diastase in this way, leave a residue,amounting to about 7% in the case of wheat starch and 15% in thatof rice starch,* which has the properties of a hemicellulose. Lingand Nan-ji, who prefer the term amylo-hemicellulose,ll communi-cate the interesting discovery l2 that this polysaccharide derivative8 AnnaZen, 1925, 443, 1 ; A., i, 636.10 Ber., 1924, 57, [B], 887.11 Compare S.B. Schryver, Biochem. J . , 1923,17, 493.12 J., 1925, 127, 625; 2. ph,ysiol. Chem., 1924, 137, 265.* The proportions actually existing in the starch are found by Ling andNaimji to be approximately 10% for wheat and 20% for rice (Zoc. cit., p. 656).@ J., 1925, 127, 62992 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.is the calcium-magnesium, or the iron, salt of a silicic ester (comparealso lichenin). It is a white powder with a fairly definite silicacontent of 0.8 to 0.9%. The sugar produced by its complete hydr-olysis is exclusively maltose, which proves amylohemicellulose to bea derivative of a-hexa-amylose.The researches of Ling andNanji on amylopectin and its deriv-atives are summarised,l3 and may be followed by reference t o thefollowing scheme.The Htphlysis of Starch with Barley and Malt Diastase.+J. J.At 55" in presence of maltoseJ.Maltose (33%,) andStable Dextrin (660/,)Maltodextrin-/IisoMal t oseMaltose + isomaltose Maltose Glucose isoMaltose (4) Maltose +Ratio 1 : 2Amylopectin (33.3%)(Dephosphated with Barley Diastase)ap-Hexa-amylose (1)(Hydrolysed with Malt Diastase).- +$+at 55'' in absence of maltose (at 70")Maltose (33 yo)Maltodestrin -/3 -1 Maltodextrin-a (2)S-Clucosidomaltose (3) i \1.L.1 J 1 '4Limit 2 : 1p - Glucosidomaltose .-The trihexose l4 previously obtained fromamylopectin has now definitely been shown to have this constitu-tion, Taking advantage of an observation of Neuberg and Sane-yoski15 that the osazones of the bioses are capable of being hydr-olysed by enzymes, the action of the a- and p-enzymes, maltase andemulsin, on the osazone of the trihexose was examined; under theaction of maltase the products were glucosazone and isomaltose,under that of emulsin they were maltosazone and glucose.The con-stitution of the trihexose is therefore P-glucosidomaltose,C , H l 1 0 5 0 0 * C 6 ~ , , 0 4 0 0 * ~ 6 ~ l ~ ~ ~ .The structure of isomaltose is a t present uncertain, that previouslysuggested, viz., 1 : 5-glucosidoglucose, belonging to cellobiose. Thep-linkings used in the formula, e.g., (I) and (11) on p. 93, torepresent the isomaltose unit may either be 1 : 5 or 1 : 4, and theoxidic ring, butylene or amylene-oxide, respectively.The structure (I), previously assigned to @-hexa-amylose, de-mands the production of the two trihexoses named on the figure.Since the action of malt diastase a t 70" results exclusively in the pro-duction of p-glucosidomaltose, a modification is necessary, and of thestructures which could yield this trihexose as sole product, formula1s J., 1925, 127, 636.l* Ling and Nsnji, J., 1923,123, 2666.Biochem. Z., 1911, 34, 44ORGANIC CHEMISTRY. 93(11) is preferred, since it is in agreement also with observations onthe stable dextrin now to be described.In this connexion the authors have shown that, whilst a-hexa-amylose is converted by malt or barley diastase a t 50" into maltose,without the formation of intermediate products, ap-hexa-amylose,treated with malt diastase a t 70", gives p-glucosidomaltose.Afurther set of observations 16 shows that ap-hexa-amylose, treatedwith malt diastase a t lower temperatures, wix., between 30" and 70°,and in presence or absence of maltose,.gives rise to a series of pro-ducts intermediate between it and p-glucosidomaltose. The natureand formation of these products will be seen by reference to thescheme given above. The term maltodextrin is applied to all thenon-crystalline, intermediate products of the action of diastase on(111. )Pectic acid.(1.1afl-Hesa-amylose.starch possessing cupric-reducing power. The " stable dextrin "shown in the scheme is regarded by Ling and Nanji as a malto-dextrin of the highest type.Maltodextrin-a, C,,H,,O,,, and malto-dextrin-B, C2,H4,0,,, were isolated by Ling and Baker in 1895.17These three dextrins are now considered to be the only distinct typesof maltodextrin existing.The " stable dextrin " was first obtained by Brown and Morrisin 1885 l* as an invariable product of the hydrolysis of starch pasteby malt diastase a t 50". The determination of its constitution is aproblem of great importance both from a chemical and a technicalpoint of view. In order to attack this problem, Ling and Nanjistudied the origin of the dextrin, the conditions of its formation,and the nature of its products of hydrolysis with malt diastase.The stable dextrin was prepared in nearly theoretical yield bythe action of malt diastase on starch at 40".Amylopectin orc$-hexa-amylose, when treated with this enzyme between 30" andIs J., 1885, 47, 643.16 LOG. cit., p. 636. l7 J., 1805,67, 703; 1897,71, 51794 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.70" in the presence of excess of maltose, is converted one-third intomaltose and two-thirds into stable dextrin. In the absence ofmaltose, however, ap-hexa-amylose itself gives no stable dextrin.The molecular weight of this dextrin is of the order of 1923 andits reducing power R 14. The first factor would agree with theformulation of the dextrin as an open-chain compound of 12 hexoseresidues. The second, on the other hand, would exclude a com-pletely closed-chain structure. The considered view of the authorsis that it is partly composed of a closed-chain and partly of an open-chain structure, the basal molecule of both being the same.Theyregard it as a mixture, possibly a co-ordinated mixture, of two com-ponents, one of which is an open-chain compound identical with themaltodextrin p of Ling and Baker (M.wt. 693), the other a closed-chain compound of very much higher molecular weight with thesame C,, unit representing its closed-chain basal structure. Con-siderations based upon the reducing power of the various productsobtained upon fission lead to the conclusion that ap-hexa-amylosemust have the formula (11) given above and that maltodextrin-f3must possess the skeletal formula (IB) in the annexed scheme :[O r o 0-J) + Oa ro ,J-I--- 01 ---0s I01 LI---.-.-- I Oaj I.-+i ----o -8J 0 I-1 * _(14 (IB)0s 010sThe stable dextrin thus consists of two molecules of.a polymeriseltetra-amylose corresponding to maltodextrin- p (IA), united withone molecule of maltodextrin- p ( IB) .The constitution of maltodextrin-a was determined by similarconsiderations, coupled with the fact that it is formed when starchis hydrolysed by malt diastase at 70". It must be regarded as anintermediate product of the degradation of ap-hexa-amylose toP-glucosidomaltose. Its constitution and relationships are shownin the following scheme : .9@-Hexa-amylose. MaItodextrin-a. /3-GlucosidomaltoseORGANlC CBEMIS'PRY. 95By the polymerisation of p-glucosan (1 : 6-anhydroglucose)Pictet 19 has obtained four synthetic dextrins, these being di-, tetra-,hexa-, and octa-glucosans, respectively, no polymeride containingan odd number of units being observed.Irvine and Oldham,20 byusing zinc as a catalyst, have now prepared three new products,apparently a hepta-, a tetra-, and a tri-glucosan, which, in contrastwith those described by Pictet, readily yield a triacetate and con-tain three hydroxyl groups for each C, unit. But these hydroxylgroups are not uniformly distributed as they are with the isomericsubstances cellulose and hexa-amylose. The latter yield 2 : 3 : 6-trimethyl glucose and no other sugar. The synthetic dextrins areconstituted on a different model from that of these natural poly-saccharides, for on similar methylation treatment they give methyl-glucosides of 2 : 3 : 5 : 6-tetramethyl glucose, 2 : 3 : 5-trimethylglucose, and a dimethyl glucose which must be either 2 : 3- or 2 : 5-dimethyl glucose.Synthetic di(trimethylg1ucosan) gave the di-and the tetra-methyl glucose in the ratio of equal molecules, and thepoly(trimethylg1ucosan) gave the di-, tri-, and tetra-methyl glucosein equal molecular proportion.There is now, therefore, a series of polymerides from mono- toocta-glucosan with the exception of the penta-form. Monoglucosanyields 2 : 3 : 5-trimethyl glucose only, diglucosan yields a mixturefrom which trimethyl glucose is absent. The others all yield thissugar in equimolecular proportion with other homologues. A con-sideration of the mechanism of the polymerisation is based on thesignificant fact that all the polyglucosans yield a tetra- and a di-methyl glucose.The first action is the conversion of glucosan intoglucose, and the dimeride must then be formed, so that there are fourhydroxyl groups in one glucose residue to two in the other. Thefollowing structure is provisionally assigned to diglucosan :rFHI +HoOH~ ~ H - ~ - ~ ~ o c ~ ( ~ H ~ ~ c ~ ~ o H ) o bFH*OH r 0- 1!CHL-CH,In the case of triglucosan, the glucose residue is shown to beattached a t the terminal carbon atom C*.Pectins.-A distinct advance in our knowledge of the constitutionof this group of plant products has resulted from the observationthat when the linking of the constituent units of polysaccharides isother than 1 : 6, acids of the nature of conjugated glycuronic acid areHdu.C h h . Acta, 1918,1,226. go J., 1925, 127, 290396 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.formed by oxidation in alkaline or neutral solution.21 Thus lactosegives finally galacturonic acid, and sucrose glycuronic acid. Theseuronic ” acids should be formed from any polysaccharide in whichthe terminal carbinol group is free, and the potential reducing grouplinked. The pectins are known to be partly constructed of suchgalacturonic acid units, and a method for the estimation of “ uronic ”acids based upon their quantitative decarboxylation is described.Until recently, it was considered that there were three pectin sub-stances in plants, viz., the insoluble parent compound, protopectin,which, during the ripening process, gave rise to the soluble pectinogen,and this, on further de-esterification, was converted into pectic acid.It is now shown that iron is a more important constituent of thesesubstances than calcium-magnesium and that protopectin is, in allprobability, nothing but pectinogen in loose combination withmetallic ions, chiefly iron ions.There would then be two pectinsubstances only, pectinogen and pectic acid, and a critical study ofthe evidence leads the authors to conclude that the relation betweenthem is such that the only change \involved in the formation of pecticacid lies in the de-esterification of pectinogen and that the basalmolecules are identical. Since tetragalacturonic acid has beenobtained by the hydrolysis of pectic acid, the basal molecule cannotbe C17H24016 as suggested by previous workers,22 whilst the fact thatpectic acid contains 70.56% of galacturonic acid suggests that thebasal molecule is composed of six units, four of which are galacturonicacid units, the others being an arabinose and a galactose residue.There will thus be four free carboxyl groups in pectic acid.Pectinogen, which contains 6 to 9% of methoxyl groups, is regardedas the di- or tri-methyl ester.A schematic formula embodying theseopinions will be found on p. 93 (111), in which the sign + representsa carbinol group, @ a carbonyl group, and * a linking other than 1 : 6.The similarity of this structure to that of the basal molecule of theconstituents of the starch granule is noteworthy.In criticism of the statement that there are only two pectic sub-stances, a microscopical and chemical study has led M.J. Carrd 23to the conclusion that protopectin (preferably called pectose) ischemically different from the pectin to which it gives rise and thatboth are normally present in ripe fruit.Lignin.-The lignin isolated from flax by resolution with sodiumhydroxide was found 24 to have the formula C4SH48016 and to con-tain in this unit one active aldehydic group and nine hydroxy-groups,(621 D. N. Nanji, F. J. Paton, and A. R. Ling, J . SOC. Chem. Ind., 1925, 44,22 S. B. Schryver and D. Haynes, Biochem. J., 1916, 10, 639.2 6 3 ~ .Biochem. J., 1925, 19, 257. 24 Ann. Report, 1924, p.87ORGANIC CHEMISTRY + 97of which four were methylated. The application of similar methodsof investigation to the lignins obtained from various woods-poplar,birch, ash, spruce, larch, and pine-has shown25 that all theselignins are derivatives of the same hydroxy-compound,for which the name lignol is suggested. They differ only in thenumber of methoxyl groups present, which varies between 3 and 5.The isolation of lignin as sodium lignate has also been employedby M. M. Mehta,26 who finds that with 4% sodium hydroxidesolution, under 10 atmospheres pressure, the lignin is removedfrom all plant materials in 1 hour. The proportion of lignin foundby this method in a number of woody tissues is very much lowerthan that obtained by the hydrochloric acid method, but it isclaimed that the product represents more nearly the original ligninof the plant.This lignin melts a t 170" and has an iodine value of 139 andan acid value of 477.It is soluble in alcohol and dilute alkalis.The author considers that lignocellulose is a compound of a glucosidictype, the phenolic hydroxyl group of lignin condensing with thecarbonyl group of the reactive form of cellulose believed to bepresent in woody tissues.If hydrochloric acid (d 1.22) is allowed to act for a short timeonly on the wood substance, a lignin of a new type is obtained.27It is a light yellow powder, insoluble in the usual solvents, butsoluble in trichloroacetic acid, from which it is reprecipitated bywater in a form soluble in alkalis, acetone, etc.Heated a t 200°, itgives some 60% of its weight as a sublimate consisting of vanillic acidwith a little vanillin, but these products are the result of oxidation,as, in an inert atmosphere, neither is produced. The residueseems to be a decomposition product of dextrose, which supportsthe conclusion, previously drawn, that lignin is a 1 : 3 : 4-benzenederivative bound to a glucoside residue. It is regarded as a colloidalconiferin complex, evidence for this view being obtained from acomparison of the action of various reagents on lignin and onconiferin, respectively.The investigation of the lignosulphonic acid obtained fromspruce wood by the action of sulphurous acid, in the absence ofa base, at loo", reported last year 28 has led to a number of pub-lications on this simple method for the resolution of lignified tissues.C,*H~O*(CO),(CHO)(OH),,25 W.J. Powell and H. Whittaker, J., 1925, 12'9, 132.26 Biochem. J., 1925, 19, 958.27 K. Kiirschner, Brennatofl-Chem., 1925, 6, 117, 208, 304; B., 1926, 912;28 Ann. Report, 1924, p. 87.Milcrochem., 1925, 3, 1; A., i, 890.REP.-VOL. XXII. 98 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The c26 acid so obtained29 was stated by P. Klason3O tobe a mixture of a dibasic and a monobasic sulphonic acid,C40H400 12, 2H,S 0, and C40H400 12 ,H2S O,, respectively . He finds,however, that under the mildest possible conditions of the actionof sulphurous acid an acid, C,oH300,,H2S0,, is obtained which heconsiders to be the correct formula for this lignosulphonic acid.Under drastic treatment with sulphurous acid, a product wasisolated (as the p-naphthylamine salt) which appears to be thesulphonic acid of conif erylaldehyde.Provisionally, therefore,or-lignosulphonic acid is regarded as a sulphonate of polymerisedconiferylaldehyde. The opinion of Klason that his aldehydicor-lignin, C20HZ006, reacts with sulphurous acid by reason of thepresence of an acraldehyde or similar unsaturated aldehydic residuehas been examined by E. Hagglund,31 who finds that, with acralde-hyde itself, the sulphonic acid group attaches itself to the p-carbonatom relative to the aldehydic group, and not the a-one. It isshown that cinnamaldehyde undergoes a condensation of thealdol type with hydrochloric acid, and some of the anomaliesobserved in connexion with the reaction of lignosulphonic acidswith p-naphthylamine may be explained by the probability thator-lignosulphonic acid may undergo a similar aldol condensation.The addition of 0.1 to @5y0 of ammonia to the 7% sulphurousacid solution improved the process of resolution of lignified fibresout of all proportion to its active mass.32Plant Cuticles.-Some confusion has arisen by the use of theterms adipocellulose and cutocellulose for cork and cuticle, re-spectively. It is shown33 that the outer layer of the cuticle ofplants (as distinct from the cutinised layer) does not contain cellu-lose, and the term plant cuticle is preferred.The cuticle fromAgave arnericana has been carefully examined with a view to acomparison with the (ancient) cuticle found in bituminous coals.After suitable purification, the product, for which the term cutinis suggested, appeared to be definite.By the action of alcoholicpotash two acids were obtained from it : C,,H,,O,, cutic acid, andC13H2203, cutinic acid, the former being in greater proportion.The oleocutic acid described by Fremy appears to be a mixtureof these two semi-liquid acids.Cel2uZose.-The formation between cellulose and alkali hydr-oxides of definite compounds of the type (C,H1OO,),,M*OH is now2B C. Dor6e and L. Hall, J. SOC. Chem. Ind., 1924, 43, 2571.; A., 1924, i,30 Ber., 1926, 58, [B], 375, 1761; A., i, 371, 1246.3l Cellulosechem., 1925, 0, 29; A , , i, 643.32 C.F. Cross and A. Engolstad, J. SOC. Chern. Ind., 1925, 44, 2 6 7 ~ .33 V. H. Legg and R. V. Wheeler, J., 1925, 127, 1412.1048ORGANIC CHEMISTRY. 99regarded as established. These compounds are shown to be stableonly in aqueous alkaline solutions of medium concentrations andW. Vieweg,3* who has re-examined the question, proves that thecompounds do not exist in the aqueous-alcoholic solutions usuallyemployed for their investigation. These conclusions are confirmedby E. Heuser,35 who considers that the existence of the compound,( C,H,oO,),,NaOH, in solutions containing 16-24y0 of sodiumhydroxide is quite definite. That it is a chemical union is sup-ported by the fact that lithium and potassium hydroxides alsoreact with cellulose in the same molecular ratio, (C6H1006)2 : M*OH ;the compounds are stable, respectively, in solutions containing9-11Yo of lithium hydroxide and 25-35y0 of potassium hydr-oxide.36 Strong organic bases also 37 show a similar behaviour,some, such as trimethylsulphonium hydroxide, forming compoundsof the molecular ratio 2 cellulose : 1 base; others, such as tetra-methylammonium hydroxide, combining in the ratio 3 cellulose : 1base.With rubidium and czesium hydroxides, compounds areformed in the ratio (C,H,,O,), : M-OH, the caxium compoundbeing stable in solutions containing 45-60% of czsium hydroxide.These ratios represent the limit of chemical combination observed,the higher ratio, C6H1,0, : M-OH, indicated originally by Vieweg,not being confirmed. The swelling of the fibres in alkaline hydr-oxide solutions of various concentrations 38 proceeds up to thepoint a t which the compound is formed.Solutions of alkali hydr-oxides a t the concentration a t which the electrical conductivity isat a maximum produce maximum swelling. Ions with lowestatomic volumes are associated with the highest number of watermolecules, and the explanation given is that the alkali ion, enteringinto combination with the cellulose molecule, carries its associatedwater with it and distends the cellulose. The ionic nature of thealkali-cellulose union is supported by the fact that reaction doesnot proceed in alcoholic solution. In another memoir,39 it is alsoshown that maximum swelling occurs in solutions of the hydr-oxides corresponding with the fully hydrated ion, although theconnexion between maximum swelling and electrical conductivityis not confirmed.Thus with the lithium ion, which is supposed toattract to itself 17 molecules of water, a maximum swelling occursa t 6.6% LiOH, the composition of the solution being 1 molecule34 Ber., 1924, 57, [B], 1917; A , , 1925, i, 12; 2. angew. Chem., 1924, 37,1008; A., 1925, i, 119.36 2. angew. Chem., 1924, 37, 1010; A., 1925, i, 119.36 Idem, loc. cit.37 F. Dehnert and W. Konig, Cellulosechem., 1925, 6, 1 ; A., i, 369.38 E. Heuser and R. Bartunek, ibid., p. 19; A., i, 520.30 G. E. Collins, J . Text. Inst., 1925, 16, 1 2 3 ~ .D 100 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of lithium hydroxide to 17 molecules of water.For the otherhydroxides, the corresponding ratios are : NaOH, 12H,O (15.5%) ;KOH, 7H,O (38%) ; RbOH, 6H,O (49%). Rontgen spectroscopicmethods also have been applied to the study of theseproblems.40? 4 1 ~ 4 2Hess has shown 43 that the chemical structural form of celluloses ofall origins, whatever their degree of dispersion or solubility, is practic-ally identical, in cuprammonium solution, with that of normalcotton cellulose, and that in this solution the cellulose moleculereacts in its simplest form, z)ix., C6H1005. The solvent action ofcuprammonium solution on cellulose is generally considered toresult in the formation of a complex cellulose copper anion, whichforms with the cuprammonium kation the salt(C,H , 0 $u), ,Cu( NH3)4.44Another investigation supports J5 the view that the greater partof the copper in a solution of cuprammonium hydroxide exists aspart of the complex ion CU(NH~)~++, and to explain the observ-ations recorded, the interesting hypothesis is advanced that cupram-monium-cellulose solutions are members of the class of colloidalelectrolytes typified by the soap solutions.The strong baseCu(NH,),( OH), forms with cellulose, functioning here as a weakacid, a soluble basic salt in which the kation is '' crystalloidal "and the anion " colloidal." It is proved that each cellulose-hexose unit, C6HI0O5, is associated with one atom of copper. Theanionic micelle, consisting of a larger number (n) of condensedhexose groups carrying n negative charges, is, with the n hydroxylions, equivalent to n bivalent cuprammonium ions.The " solu-tion " of cellulose, therefore, may be represented by the equation(C6H1005)?2 + nCu(NH3)4(0H),CCU(NH,)4I,(C,H,O,),( OH), nH,O,the salt being highly ionised into ~ C U ( N H ~ ) ~ + + , nOH-, and(Cl&IO5)n-.By the optical method, it has been shown that lichenin is notidentical with cellulose.46 Lichenin is depolymerised on heatingin glycerol a t 240",47 giving lichosan the molecular weight of whichshows it to be a glucose anhydride, C6H1005. It polymerises40 J. R. Katz, Cellulosechem., 1925, 6 , 35.41 J. R. Katz and H. Mark, 2. Elektrochem., 1925, 31, 105; A., i, 640.42 R. 0. Herzog, Cellulosechem., 1925, 6, 39; A., i, 639.43 2. angew. Chem., 1924, 37, 993; A., 1925, i, 118.44 K.Hess and E. Messmer, Annalen, 1924, 435, 1.45 S. 31. Neale, J . Text. Inst., 1925, 16, 3 6 3 ~ .4 6 K. Hew, 2. angew. Chem., 1924, 37, 993; A., 1925, i, 118.( 7 H. Pringsheim, W. Knoll, and E. Kaston, Ber., 1925, 58, [B], 2135; A.,i, 1386ORGANIC CHEMISTRY. 101rapidly to lichenin, the Rontgen spectrum of which is identicalwith that of the original lichenin. Lichosan is therefore probablythe parent substance of lichenin. On acetolysis, it gives octa-acetyl cellobiose, and as lichinen itself, on methylation, gives2 : 3 : 6-trimethyl glucose, the constitutionr- 0 1L 0 -ICH*CH( OH)*CH( OH)*CH*CH*CH,*OHis assigned to lichosan.The alkali-soluble form of cellulose, called by its discovererCellulose A, has been shown48 to be capable of methylation upto a methoxyl content of 45% (a trimethyl cellulose requires 45.6%),which is higher than that so far obtained from the ordinary in-soluble cellulose.Hydrocellulose also yields a trimethyl derivativeapparently identical with trimethyl cellulose A and, like it, forminga colloidal solution in water. Both products, on treatment withmethyl-alcoholic hydrogen chloride, yield a trimethyl methyl-glucoside identical with that obtained from insoluble trimethylcellulose.*9 The product is, however, almost entirely in the a-formand not a, mixture of the a- and p-forms as assumed by Irvine andHirst.50 An a-configuration is therefore assigned to trimethylcellulose. Cellulose A forms the best starting point for the prepar-ation of 2 : 3 : 6-trimethyl glucose, the glucoside being obtained fromit in a yield of 88%.The authors comment on the remarkable factthat the same trimethyl glucose is obtained from the methyl ethersof such chemically different polysaccharides as cellulose, li~henin,~lstarch,S2 and p-he~a-amylose.~3The production of cellobiose through the acetolysis of cellulosehas occupied a prominent place in constitutional questions relatingto cellulose. W. Weltzein and R. Singer 54 in conjunction withK. Hess find that the action of acetic anhydride, containing 10%of sulphuric acid, on cellulose yields cellobiose octa-acetate, cello-dextrin acetates containing celloisobiose, and derivatives of themonoses, in approximately equal quantities, whilst with caellulosetriacetate the products are the same, but the proportion of cello-biose octa-acetate is very much smaller.An exhaustive fraction-ation of the cellodextrin acetates was made, resulting in theirclassification into six groups of varying solubility in alcohol andether, and with optical rotations, in chloroform solution, ranging4a K. Hess and W. Weltzien, Annalen, 1925, 442, 46; A., i, 517.6o LOC. cit., p. 530.K2 J. C. Irvine, Brit. Assoc. Rep., 1922, 17.63 J. C. Irvine, J., 1924, 125, 942.J. C. Irvine and E. L. Hirst, J., 1923,123, 620.61 Helv. Chim. Acta, 1924, 7, 366.AnnnTen, 1925, 443, 7 1 ; A., i, 641102 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.between - 24" and + 20". The best crystallised fraction of thesecellodextrin acetates yielded a celloisobiose, which was shown to beidentical with that described by Prosiegel and Knoth.Since celloisobiose octa-acetate cannot be transformed into cello-biose octa-acetate under conditions of acetolysis, it is probable thatthe conversion of cellulose into dextrose takes place through cello-isobiose and not directly.Investigations on this point and on theconstitution of celloisobiose are in progress, for the importance ofthis sugar as a first degradation product of cellulose-acetolysisis emphasised. If celloisobiose and not cellobiose is the primaryproduct of acetolysis, its quantitative formation from cellulosebecomes a possibility, which is under examination, and the formulaof Irvine, which was based upon a yield of cellobiose of 50%, wouldneed revision.T. O ~ a w a , ~ ~ by the acetolysis of sulphite woodpulp, claims to have obtained cellobiose octa-acetate in a yieldof 90% without any dextrose as a by-product, his conclusion beingthat cellulose is a complex of polymerised cellobiose units.Cellulose triacetate has been prepared 56 in well-defined crystalsfrom solutions in tetrachloroethane, the colloid apparently crystallis-ing in combination with the solvent. The mixture of di- and tri-acetates of which the acetone-soluble cellulose acetate, " cellite,"is composed can also be crystallised from hot benzene-alcoholsolution, the crystals being stable only in contact with the liquid.After 40 recrystallisations, the cellulose obtained on hydrolysiswas identical with the original cellulose, so that the existence ofmore than one isomeride in natural cellulose is unlikely.It is remarkable that the study of the oxidation of cellulose hasnever thrown any light on its constitution.No definite product ofoxidation, indeed, can bc found in the so-called oxycellulose, whichappears to consist of cellulose and cellulose A, with mechanicallyadherent compounds in minor proportion. The development ofcarboxyl groups 57 during oxidation, however, requires explanation.An interesting research58 defines more exactly the nature andformation of the oxycelluloses. It is shown that the oxycellulosesfall into two classes, (a) the non-reducing type with a markedaffinity for methylene-blue and power of fixing alkalis; coupledwith the low reducing power evidenced by small copper numberand slight solubility in sodium hydroxide solutions, (b) the reducingtype with high copper numbers and marked solubility in alkalinesolutions, but with low absorptive power for basic dyes and for6 5 J .Chem. Ind. Japan, 1924, 27, 884; A., 1925, i, 234.66 K. Hess, 2. angew. Chem., 1024,37, 993; A., 1925, i, 118.57 K. Hess, Papier-Pabr., 1925, 23, 122; A., i, 519.6 8 C. Birtwell, D. A. Clibbens, and B. P. Ridge, J . Text. Inst., 1925, 16,13; A., i, 234ORGANIC CHEMISTRY. 103alkalis. Oxycelluloses of type ( b ) , when boiled with dilute alkalis,become chemically indistinguishable from normal cellulose, whereasthose of class (a) are not altered by such treatment.The type ofoxycellulose produced is dependent on the alkalinity or acidity ofthe solution, those of type ( a ) being produced under alkaline, thoseof type ( b ) under acid conditions, A careful study of the variationproduced with hypochlorites and hypobromites of increasinghydrogen-ion concentration shows that from pH 12 to pR 2.7 thereis a rise in the copper number from 0.6 to 3.7 and a fall inthe methylene-blue absorption from 2.1 to 0.9, rapid changeoccurring near the neutral point.Compouds of Nitrogen and of Sulphur.The number of papers dealing with compounds containingnitrogen is very large and it is only possible briefly to refer toone or two. By the action of nitric acid on sodium fulminateat - 18", isocyanilic acid has been prepared for the first time inquantity.59 It is now shown that the acid is tetrameric, the silversalt being C4H,04N4Ag.By energetic treatment with thionylchloride, a substance, C40,N4, is obtained, accompanied by thefuroxandicarbonamide of Ulpiani. The substance C402N4 is thenitroacetonitrile of Steiner. It is now shown to have the consti-tution of dicyanofuroxan, C(CN):N(:o)>O, and isocyanilic acid&cN)==Nitself is deduced to be the dioxime of furoxandialdehyde,fr(CH:N*OH):N( :O)>o.C( CH:N*OH)==NThe acid was also synthesised from syn-chloroglyoxime by theaction of sodium hydrogen carbonate, the intermediate substance,CH(:N-OH)CiN:O, polymerising to the ring compound.A lengthy contribution on the nature of thiocarbamide and thethiuronium salts60 adduces proof that the acid hydrogen in thesalts of thiocarbamides is attached to the sulphur atom.Accord-ing to the position of the positive charge in the thiuronium ion,the salts may be of the sulphonium, carbonium, or immoniumtype, viz., (NR,),C:SR, (NR,),C-SR or (NR,)*SR-C:NR,. Theseideas are shown to be improbable and the basic function is prob-ably divided between the two nitrogen atoms, the ionic chargealternating from one to the other. A similar dynamic formula issuggested 61 for the guanidinium ion.4- + +69 H. Wieland and others, Annnlen, 1925, 444, 7 ; A., i, 1048.60 H. Lecher and others, ibid., p. 36; A., i, 1390.61 H. Lecher and F, Graf, ibid., 1925, 445, 61; A., i, 1392; compare A.,2924, i, 1051104 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.A product of hydrolysis of the proteins hitherto undescribedhas been isolated62 from isinglass.It is a strong base with theformula C,H,,O,N,, giving a tribenzoyl derivative. The evidenceseems to indicate that it is ae-diamino- p-hydroxy-n-hexoic acid andthe name " oxylysine '' is proposed. Its presence has been demon-strated in a variety of protein substances.A series of investigations G3 on the important biochemical productglutathione has culminated in a brilliant synthesis64 of this com-pound. Glutamic acid was converted into the hydantoinpropionicacid (I) by Dakin's method. The acid bromide of this, coupledwith cystine dimethyl ester hydrochloride in the ordinary way,gave di( hydantoinpropiony1)cystine (11).Boiling with calciumhydroxide opened the ring with the formation of a uramino-acid(111), which, on treatment with nitrous acid, gave the amino-acid(1V)-glutathione. This product was partly racemised, but aglutathione identical with the natural product was obtained from a702H vH,*S-y 3 2 UH*NH*CO*TH,(1). YH2 -+ hO,H YH, (11.1 -+( J H O N H > ~ ~ CH*NH>CObO*NH &O*NHVH,*S- FH2.S-cH*NH*CO 5?H2 VH*NH*CO*YH,(111.) bO,H VH2 C0,H QH2 PV.1YH*NH*CO*NH, CH*NH,C02H bO,Hglutamyl monobromide, prepared by the action of phosphorustribromide on glutamic acid, which was shown to have the con-stitution BrOC*CH,*CH,*CH(NH,)*CO,H. This substance whencoupled with cystine dimethyl ester gave diglutamylcystine orglutathione.These methods apply to the synthesis of all dipeptidesof the type R>CH*NHCOCH,*CH,*CH( NH,)*CO,H.CHARLES DOR~E. R,62 S . B. Schryver, H. W. Buston, and D. H. Mukherjee, Proc. Boy. Soc.,63 H. E. Tunnicliffe, Biochem. J., 1925, 19, 194, 199.64 C. P. Stewart and H. E. Tunnicliffe, ibid., p. 207.1925, B, 98, 58; A., i, 794ORGANIC CHEMISTRY. 105PART II.-HOMOCYCLIC DIVISION.Stereochemistry of Nitrogen, Sulphur, and Arsenic.Geometrical Isomerism of 0ximes.-The customary oxime con-figurations have long been taken for granted, and therefore therecent suggestion that they require inversion arrests attention.The methods which until recently had been generally acceptedare based fundamentally on the theory of preferential cis-inter-action. Thus Hantzsch’s method of orienting aldoximes, whichhas been employed since 1891, depends on the fact that the acetylderivative of one geometrical isomeride regenerates the parentoxime on treatment with alkalis, whilst the acetyl derivative ofthe other loses acetic acid, giving the nitrile; the assumption thatelimination can take place from cis- but not from trans-positionsunder the conditions employed is arbitrary.Similarly, in ascribingconfigurations to ketoximes on the basis of the Beckmann change,a cis-interchange of radicals is postulated :It has, however, long been known that preferential cis-eliminationand cis-addition, in spite of its simple mechanical interpretation,is not the rule amongst ethylenic compounds. Indeed, the occur-rence of the Walden inversion, proving that in substitution thenew group does not necessarily enter at the disrupted bond, appearsto establish the possibility not only of trans-addition to doublelinkings but also of trans-scission of rings :R;\R’f/XU+ R-C-R +R k /Rff,XY+R-C=C-R +Reversal of trans-addition leadsinterchange may be regarded asX-C-R /R:f + y I (Inversion)\ ~ , j f RT Ito transelimination, whilst tram-two mutually dependent internal - -substitutions. If, as is generally conceded, the initial stage insubstitution and rearrangement is the formation between theinteracting molecules or groups of a residual linking, which subse-quently establishes itself at the expense of another bond, thenD106 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Werner’s theory of the Walden inversion 1 can be extended to allthese cases : the application to the Beckmann rearrangement,regarded as a trans-interchange, would beR-C-R‘ R’-C-OH R’-GOR-NH II --+ I -+ ***..1 I *I...“-OH R-NThis view of the course of the Beckmann change, which was firstadvanced by H. Bucherer as early as 1914,2 is therefore clearlyconsistent with other known phenomena relating to substitution 9etc. If, however, it were found to apply generally, it would benecessary to reverse all configurations previously assigned tooximes on the basis of the Beckmann rearrangement.The f i s t evidence in favour of reversal was advanced by J.Meisenheimer in 1921 , who showed that triphenylisooxazole onfission by the ozone method yielded the benzoyl derivative ofp-benzilmonoxime, which must therefore be formulated as follows,although the opposite configuration had previously been assignedto this oxime on the basis of the Beckmann change :It follows that the Beckmann rearrangement must involve trans-interchange thus :Ph*C-COPh / Ph*NC + CO,H*Ph’*‘*.l:L()H \ PhNH.CO.COPhVarious observations have since been made tending to confirmthis conclusion.Thus the oximes of o-chloro- and o-bromo-benzo-phenone, which by the Beckmann rearrangement yield anilides ofthe substituted benzoic acids, pass with ease into benzisooxazoles :y6H4*GPh + C,H,Br$Ph + C6H4Br*~*OHO-N HO*N PhNSimilar deductions have been drawn from the study of other ortho-substituted aromatic ketone^,^ although the results are not in allcases conclusive.61 A.Werner, Ber., 1911, 44, 881; A., 1911, i, 424.8 Ber., 1921, 54, 3206; A., 1922, i, 152. Compere Ann. Report, 1922,4 J. Meisenheimer and H. Meis, ibid., 1924, 57, 289; A., 1924, i, 433.6 K. von Auwers and 0. Jordan, ibid., p. 800; A., 1924, i, 743; ibid.,1925, 58, 26; A., i, 264; K. von Auwers, M. Lechner, and H. Bundesmann,ibid., p. 36; A,, i, 265.‘‘ Lehrbuch der Farbenchemie,” p. 202.p. 8.6 Compare 0. L. Brady and G. Bishop, J., 1925, 127, 1358ORGANIC CHEMISTRY. 107The only case recorded in the literature in which the conversionof an oxime into a ring compound points to a Configuration inharmony with the older conception of the Beckmann rearrange-ment is that of benzoin-cc-oxime, which, according to E. Fischerand H.Hiitz,' is converted into an indole derivative, whereas the(3-oxime does not behave in this manner :Ph$*CH( OH)-/\ Ph * G*CH( OH)*{)\/ N*OH \/ I I - + NHowever, doubts about the constitution of the ring compoundhave been expressed by Fischer, and definite proof that it is not2-phenylindoxyl is afforded by L. Kalb and J. Bayer's synthesisof the latter, and its non-identity with the product obtained byFischer and Hutz. The compound must therefore be 2-phenyl-l-hydroxyind~le,~ and its formation from an oxime of the oppositeconfiguration to that depicted above can be explained, conformablywith Robinson's theory of the Wagner transformation, by meansof a six-membered partial valency cycle, involving (as in Bucherer'sview of the Beckmann change) a partial linking between the benzenering and the unoccupied side of the nitrogen atom :This case, therefore, falls into line with that view of the Beckmannchange which involves transposing the configurations customarilyassigned to ketoximes.In the case of aldoximes, the question a t issue is whetherHantzsch's assumption of the &-elimination of acetic acid fromthe acetyl derivative is correct.Arguments in favour of trans-elimination have been adduced by E. Beckmann, 0. Liesche, andE. Correns lo and by K. von Ahwers and B. Ottens,ll but the mostimportant evidence on the subject is that advanced by 0. L. Bradyand G. Bishop.12 The two forms of 2-chloro-5-nitrobenzaldoximewere prepared and oriented by Hantzsch's method.It was thenfound that the oxime whose acetyl derivative lost acetic acid inthis process readily underwent ring closure, yielding an isooxazole' Ber., 1895, 28, 585; A., 1895, i, 371.a Ibid., 1912, 45, 2150; A., 1912, i, 727.J. Meisenheimer and H. Meis, loc. cit.lo Ber., 1923, 56, 341; A., 1923, i, 228.l1 Ibid., 1924, 57, 446; A., 1924, i, 516. l2 J., 1925, 127, 1357.D* 108 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.and ultimately a hydroxy-nitrile, under conditions in which theisomeric oxime remained largely unchanged :4-(-AcOH)- NaOH + -Since ring formation would be expected to occur more readily whenthe hydroxyl group is vicinal to the halogenated phenyl groupthan when it is remote, this result indicates preferential truns-elimination of acetic acid in Hantzsch’s orientation process, and aconsequent reversal of the customary configurations of aldoximes.These authors regard their experiments rather as a significantindication than a complete proof that the configuration of aldoximesshould be inverted, and it would be desirable to maintain thisreserve for the present both with regard to aldoximes and ketoximes,if only for the following reason.All the evidence in favour ofinversion is based on the assumption that neighbouring groupsinteract most readily in ring closure, and are necessarily formedwhen a ring is broken. The first of these propositions is probablytrue in the great majority of cases; nevertheless it must be appliedwith caution, since the ready dehydration of urnphi-glyoximes l3shows that ring closure may, in certain circumstances, take placeby a mechanism which obviates any necessity for the eliminatedresidues to be originally in close proximity : l4The second gencralisation has been challenged by workers l5 whoclaim to have demonstrated “ trans-ring fission,” and although theinstances described are obviously fissions involving Walden in-versions (p.105) affecting only the configurations of groups aboutl3 J. Meisenheimer and W. Lamparter, Ber., 1924, 57, 276 ; A., 1924, i, 432.J. Meisenheimer, H. Lange, and W. Lamparter, Annulen, 1925, 444, 94;A., i, 1073.1 4 Compare Ann. Report, 1924, p. 113, and 0. L. Brady and G. Bishop,Eoc. cit.l5 R. Kuhn and F.Ebel, Ber., 1925, 58, 919, 2088; .4., i, 780, 1378; J.Boeseken, ibid., p. 1470; A . , i, 1237ORGANIC CHEMISTRY. 109the separated atoms (" Sprengstucke "),16 as, for instance, thehydrolysis of cis-ethyleneoxidedicarboxylic acid to racemic acid : l7OH(racemic acid) Ho2r/ A, ,,,/\I C0,H HO2C / COnHOH 'I + I/HIH H Hthere remain cases of so-called '' resonance action " or " nascentactivation '' in which chemical reaction in one part of a moleculebrings about some unexpected change in another.l* Now thischange may be a geometrical inversion. The formation of fumaricacid when copper maleate is decomposed with hydrogen sulphideis a case in point, for hydrogen sulphide has no action on maleicacid as such, either in the pure state or mixed with other coppersalts.l9Thus, unlikely though it may seem, the possibility is not com-pletely excluded that in Meisenheimer's experiment the fissionby ozone of one double bond of the isooxazole ring may give riseto inversion around the other, in which case the argument forinverting oxime configurations would collapse.It may, however, truly be said that the work of Brady, Meisen-heimer and their collaborators has established a strong prima faciecase in favour of inversion, although further evidence is desirablebefore the matter can be regarded as conclusively settled.I n the above discussion the geometrical character of the isomerismmet with in oximes is taken for granted-for reasons summa,risedin last year's Report.However, the complexity of oxime trans-formations is such that the Hantzsch-Werner geometrical con-ception must certainly be extended, as 0.L. Brady and P. Dunnoriginally suggested,20 by ascribing to each isomeride a tautomericcondition involving the appropriate nitrone form. The necessityCompare J. Boeseken,loc. cit.l6 J. Meisenheimer, Ber., 1925,58, 1491 ; A , , i, 1335.1 7 R. Kuhn and F. Ebel, ibid., p. 919; A , , i, 780.18 R. Anschutz, Annalen, 1887, 239, 161 ; A., 1887, i, 916; K. von Auwers,ibid., 1899, 309, 316; A., 1900, i, 84; H. Phillips, J., 1923, 123, 44; R.Stoermer and F. Bacher, Ber., 1924, 57, 15; A., 1924, i, 400; P. Walden,Ber., 1925, 58, 237; A., i, 349; R. Stoermer and P. K. Klockmann, ibid.,p. 1164; A., i, 927; F. R. Goss and C.K. Ingold, J., 1925, 127, 2776.The analogousconversion of citraconic acid into mesaconic acid is described by R. Franz,ibid., 1894, 15, 209; A., 1894, i, 403.H . Skraup, Monatsh., 1891, 12, 108; A., 1891, i, 1338.2O J., 1916, 109, 659110 ANNUAL REPORTS ON !I!IXE PROGRESS OF CHEMISTRY.for some such extension has recently been ernphasisedy2l and ithas been pointed out that the nitrone forms would necessarilyretain the distinctive geometrical configurations of the originalisomeric oximes.22 Thus it seems probable that in oxime chemistry,as in the chemistry of diazo-compounds, we encounter combinedtautomerism and geometrical isomerism, complicated also, nodoubt, by the ionisability of the individuals implicated.Without discussion of the bearing of these various factors onoxime transformations in general, reference may be made to theinterconversion of the geometrical isomerides.0. L. Brady andG. P. McHugh 23 have published a summary of the results obtainedon acylating sixteen aldoximes with eight different acylatingagents, and suggest that the changes of configuration observedare best accounted for by assuming the intervention of the nitroneform. Writing a for the configuration formerly regarded as anti,and /3 for the other one, the data may be tabulated as follows :Reagent.Acetic anhydride ..............................Benzoyl chloride ..............................Diphenylcarbamyl chloride ...............Ethyl chloroformate ........................Chloro-2 : 4-dinitrobenzene ..................Picryl chloride .................................Phen ylcarbimide ..............................a-Naphthylcarbimide ........................a-Oxime 8-Oxime(9 examples).(7 examples).a BB Ba or 8 (8) *B (8)a and B Ba aB C-,Ja B* Indicated by isolation of nitrile. t Oxime group split off.The explanation given, namely, that addition to the nitrone occursin two ways, one of which may lead to an inversion of configuration,corresponds closely with that offered by Brady and D ~ n n 2 ~ toaccount for other inversions of oxime configurations, and hasmuch to recommend it. I n its results it is equivalent to ascribinga pseudo-basic character to the isooxime structure : 2521 J. P. GriEths and C. K. Ingold, J., 1925, 127, 1698.22 In this connexion it is noteworthy that the complete set of four mono-and four di-oximes of p-methoxybenzil required by the geometrical theoryhas been described by J. Meisenheimer, H.Lange, and W. Lamparter,lOG. C i t .23 J., 1925, 127, 2414.24 LOC. Cit. 25 Ann. Report, 1924, p. 113ORGANIC CHEMISTRY. 11 1/o\ 9 >C-NH >C=NHwith consequent tautomerism in its salt-like additive products,and the possibility of geometrical inversion through the pseudo-salts :(pseudo-base. ) (base.)x X>&--NH-oR e =.C=NH.OR(pseudo-salt .) (salt.)Geometrical Isomerism of Hydraxones.-Pairs of stereoisomerichydrazones have frequently been described, but no method oforientation in which any degree of confidence could be placed haduntil recently been evolved.M. Busch, G. Friedenberger, andW. Tischbein26 have, however, described a series of hydrazonesof o-anilinoacetophenone which occur both in a (less fusible) andTo these it seems possible to assign definiteconfigurations, since the a-compounds combine with aldehydes,giving cyclic derivatives, whilst the p-isomerides yield open-chainaldehyde-ammonias and other complex substances :(more fusible) forms..1Ph*G*CH,.NHRNHR’*N.1Ph*E*CH,*yR Ph*$j*CH2*NHRN*NR‘*CHR” R”*CH( OH)*NR’*NOptically Active Sulphur Compounds.-The assumption that inoximes the hydroxyl group is bent out of the plane of the doublelinking attached to the tervalent nitrogen atom is now so familiarthat the theoretical problems to which this conception gives rise,especially when it is considered in relation to the failure which hasconsistently attended efforts to obtain optically active, open-chaincompounds of tervalent nitrogen, N-R,, /R1 tend to be overlooked.‘R3It is therefore of great interest that instances of optical activityin which only three groups are attached to the central atom havebeen recorded.27 The active compounds described are the ethyland n-butyl esters of p-toluenesulphinic acid, C,H,*SO*OR, whichwere obtained as d + Z mixtures, containing an excess of oneenantiomorph, by digesting the p-toluensulphinate of an activealcohol (Z-P-octanol) with ethyl or n-butyl alcohol ; a partial inter-change of alkyl radicals then took place in such a way as to favour26 Ber., 1924, 57, 1783; A., 1925, i, 41.27 H.Phillips, J . , 1925, 127, 2552112 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.one of the active forms, somewhat as in asymmetric synthesis.This clearly shows that in these sulphinic esters the toluene gronpmust be outside the plane formed by the sulphur atom and the twooxygefiatoms of the sulphoxyl group, the central sulphur atom andits three attached groups occupying the corners of a tetrahedron.This conclusion corresponds closely with the generally acceptedinterpretation of the optically active thionium salts described firstby Sir W. J. Pope and S. J. Peachey,28 and by S. Smiles.29 Here,it is true, there are four groups attached to the central atom, butone of these is an ionisable acid radical which cannot materiallyinfluence the spatial arrangement of the non-dissociable complex(Werner).This complex must therefore be asymmetric itself, thefour atoms in S -R, occupying the corners of a t e t r a h e d r ~ n . ~ ~Thus the two classes of optically active sulphur compounds mayboth be referred to type I (below) :[ cjPope and Peachey (1900).[o's<o!c"H 2 5 o c H 3 iPhillip (1925).Werner's principle that ionising linkings can be disregarded inconsidering stereochemical relationships enables a similar com-parison to be made between optically resolvable ammonium saltsand amine oxides; and since sulphoxides (to which sulphinic estersmay be likened) can be regarded as internal thionium compounds,related to ordinary thionium salts as amine oxides are to ammoniumsalts, a correspondence of configuration would be expected in bothcases.Thus we have two types (1 and 2) of spatial structureapplicable to those optically active compounds of sulphur andnitrogen, respectively, which have been described up to the presenttime :S[R1-s<~]+ [06S<3] 2(Thionium ion.) (Sul phoxides .)Type 1.T y p e 2.*28 J., 1900, 77, 1072.30 A. Werner, " Lehrbuch der Stereochemie," p. 317 (1904).* Any doubt which might have existed with regard to this structure isremoved by the recent investigation by W. H. Mills and E. H. Warren ( J . ,1925, 127, 2507).29 Ibid., p. 1174ORGANIC CHEMISTRY. 113Phillips's paper contains an interesting discussion of the possiblereasons for the fact that the sulphur atom does not occupy themost central position with respect to R,, R,, and R, in type 1.The obvious suggestion, to which the octet theory leads, that theplace of R, in type 2 is taken in type 1 by a '' lone pair " of electrons(A), is negatived partly on the ground of the non-asymmetriccharacter 31 of the tervalent nitrogen atom in NR,R2R,, wherethere would similarly be a " lone pair " of electrons (B) :R2 ..R2R3 R3R,:N: (B) (A) Rl:K:@ .. ..The conclusion drawn is that the positive charge associated withthe sulphur atom both in thionium salts and in sulphinic esters is-apart from the attachment of three dissimilar groups-the essentialcondition of asymmetry.Optically Active Arsenic Compounds.-Despite the probablesimilarity between the stereochemical configurations of compoundsof quinquevalent arsenic and those of corresponding derivativesof nitrogen and phosphorus, attempts to resolve arsonium com-pounds until recently met with little success, although G.J. Burrowsand E. E. Turner 32 obtained a solution of phenyl-a-naphthylbenzyl-methylarsonium iodide (I) which showed a feeble dextrorotation. Amuch more satisfactory case is now recorded by W. H. Mills and R.Raper,33 who have obtained optically pure enantiomorphous modi-fications of p-carboxyphenylmethylethylarsine sulphide (11), [M]2$4i1 + 60" and - 59".The compound (11) is constituted similarly to the amine and phos-phine oxides resolved by J. Meisenheimer, but whereas the lattersubstances are basic, forming salts of the types [R,R,R,N(OH)]Xand [R1R2R3P( OH)]X, the tertiary arsenic sulphides, R,R,R,As:S,are chemically indifferent, and the compound (11) derives itssalt-forming properties from the carboxyl group.Thus the arsenicatom is left, as far as possible, undisturbed by the processes of saltformation and decomposition necessary to the resolution, and thisfact may have contributed to its success.Mechanism of Isomeric Change.So many views have been expressed with regard to themechanism of tautomeric and isomeric changes that consider-s1 J. Meisenheimer and M. Schutze, Ber., 1923, 56, 1353; A., 1923, i, 839.s2 J., 1921, 119, 426. 33 Ibid., 1925, 127, 2479114 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.able interest attaches to cases suitable for detailed and quantitativestudy.An important investigation on this subject has beenpublished during the year by A. W. Chapman,34 who has examinedin some detail a case of the migration of a group in the amido-imidoltriad system :R 0=7-v R. o-v=Iy =e=It has frequently been suggested that in changes of this kindthe migration of the mobile atom or group is preceded by its dis-sociation from the remainder of the molecule, which then under-goes valency-rearrangement and, by subsequent recombination,produces the isomeric compound. The absence of by-productsformed by the combination of two similar radicals is thenaccounted for by regarding the dissociation as ionic in character,in conformity with the conception which assumes antecedention-formation in all organic reactions.The view that isomericchange occurs only subsequently to ionisation has recently beenapplied to rearrangements in the camphene series .35On the other hand, it has been held that such transformationsare entirely internal in character, and occur through the operationof partial valencies inside the system, without the interventionof ions.In common with other O-substituted derivatives of amides,N-phenylbenziminophenyl ether undergoes isomeric change onheating, the substituent attached to oxygen becoming transferredto the nitrogen atom of the amide group :(p (p)o-y=y -+ o=y-yPh Ph Ph PhThe reaction appears to be peculiarly well adapted to quantitativeinvestigation, as it proceeds without the formation of any by-product, and is not measurably reversible under the conditionsused.A dynamical study showed that it was strictly monomole-cular.In order to test the validity of the ionic mechanism, the electricalconductivity of the material was measured during the isomer-isation. At all stages the conductivity was small, but, as thereaction progressed, it increased from the value given by the pure34 J., 1925, 127, 1992.35 H. Meerwein and K. van Emster, Ber., 1922, 55, 2500; A , , 1922, ii, 751;H. Meerwein and R. Wortmann, Annalen, 1924, 435, 190; A., 1924, i, 188;H. Meerwein and F. Monforte, ibid., p. 207; A., 1924, i, 191; Ann. Report,1924, p. 96ORGANIC CHEMISTRY. 115imino-ether to a final steady value, which was identical, within thelimits of experimental error, with that characteristic of the care-fully purified amide.This proved conclusively that ions werepresent throughout the change, which might therefore be explainedin' terms of the ionic mechanism in the following manner :provided that appropriate assumptions with regard to the relativevelocities of the component changes were made to account for themonomolecular character of the complete reaction.It therefore remained to ascertain whether these ions are reallyresponsible for the transformation, and for this purpose the factwas utilised that N-p-tolylbenzimino-p-tolyl ether undergoes re-arrangement a t the same temperatures as N-phenylbenzimino-phenyl ether. If the change is ionic in one case, it should be soin the other, and a mixture of the two imino-ethers should giverise to ions which on recombination would yield, not only thetwo symmetrical products (I and 111), but also the phenyl-p-tolyl-compound (11) :No such interchange of groups occurred, each rearrangementproceeding independently of the other.It is, therefore, clear thatthe isomeric change of imino-ethers into substituted amides doesnot involve prior fission into ions, but is a purely internal process.Since this inference can probably be extended to other similarmolecular rearrangements, the conclusion may be drawn that theionic hypothesis is not generally applicable to such changes, althoughit may constitute a facilitating mechanism in certainMigratory Tendencies of Different Groups.-Numerous papershave been published within recent years on the relative migratorytendencies of different groups in the rearrangements which oftenaccompany the dehydration of a-glycols.It appears, however,that the controlling conditions are somewhat complex. In the36 Ann. Report, 1924, p. 98116 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.general case migration can obviously occur from either of thehydroxyl-bearing carbon atoms to the other :and a variety of carbonyl compounds may be formed, in additionto ethylene oxides-complicating factors which greatly increasethe difficulty of comparison. It appears, for instance, that inthe dehydration of a-naphthylhydrobenzoin all the possible productsare formed simultane~usly.~~A considerable simplification of method seems to have beenprovided by the discovery, by McKenzie and his collaborators, ofthe " semipinacolinic deamination " of amino-alcohols by means ofnitrous a ~ i d , ~ 8 since in this change migration occurs always awayfrom the hydroxyl-bearing carbon, as in the following case : 39Moreover the reaction does not appear prone to yield ethyleneoxides,Bo as was formerly supposed.41 If, therefore, two differentradicals are attached to the carbon atom bearing the hydroxylgroup, a decision with regard to their relative tendencies towardsmigration can be obtained. In this way the following comparisonshave been made : (a) p-anisyl>phenyl 42 (which agrees with con-clusions based on the more complex glycol dehydrations) ; 43( b ) phenyl7 a-naphthyl (glycol dehydrations had led to incon-clusive results) ; 44 ( c ) phenyl>meth~l.~~ It is to be hoped that37 A.McKenzie and W. S. Dennler, J., 1924,125, 2105; A. McKenzie andR. Roger, ibid., p. 844; A. Or6khov and M. Tiffeneau, Compt. rend., 1924,178, 1619; A., 1924, i, 729.38 A. McKenzie and A. C. Richardson, J., 1923,123, 79; A. McKenzie andW, S. Dennler, loc. cit. ; A. McKenzie and R. Roger, loc. cit. ; A. McKenzieand G, 0. Wills, J., 1925, 127, 283.30 A. McKenzie and G. 0. Wills, Zoc. cit. Compare F. Bettzieche, 2.physiol. Chem., 1924, 140, 273; A., 1925, i, 251.40 A. Orekhov and M. Roger, Compt. Tend., 1925,180, 70; A., i, 261.4 1 C. Pad and E. Weidenkaff, Ber., 1905, 38, 1686; 1906, 39, 2062; A.,1905, i, 436; 1906, i, 583.42 A.Orkkhov and M. Roger, Eoc. cit.43 M. Tiffeneau and A. Orkkhov, Bull. SOC. chim., 1925, (iv), 37, 430;44 A. McKenzie and W. S. Dennler, loc. cil. ; A. Ordkhov and M. Tiffeneau,d5 A. McKenzie and A. C. Richardson, Zoc. cit. ; A. McKenzie and R. Roger,A., i, 679.loc. cit.loc. CitORGANIC CHEMISTRY. 117further comparisons of this kind will be made, as the results cannotfail to be of importance in relation to the theory of affinity dis-tribution and its effect in facilitating isomeric change.With regard to the mechanism of these deaminations, it is clearthat they take place without the intermediate formation of glycolsor ethylene oxides.46 The explanations that have been suggestedhave been based on the conception of intermediate free radicals,as indicated by the preceding formulae.On the other hand, ethyleneoxides are known to undergo the corresponding rearrangements,although a t higher temperatures.47 It seems probable thatelimination of nitrogen from a cyclic diazo-oxide may fulfilthe same part in promoting the semipinacolinic deaminationas the elimination of water does in the Wagner rearrangement, themecha,nism of which was discussed in last year’s Report.Auto-oxidation and the Structure of Oxonides.It has long been known that when an unsaturated substance isoxidised by atmospheric oxygen in the presence of another com-pound incapable, under ordinary circumstances, of auto-oxidation,the latter also is sometimes oxidised. This phenomenon was a tone time described as the “ activation” of oxygen, and was re-garded as a consequence of the formation either of ozone or ofhydrogen peroxide.It was shown, however, by Engler and others 48 that the oxidisingagent produced during auto-oxidation is neither ozone nor hydrogenperoxide but a compound with oxygen of the unsaturated substanceitself.In the case of pinene, for instance, the activity of the auto-oxidation product is retained for years if the material is kept inthe dark, and the active constituent remains in the residue whenmuch of the unchanged pinene is removed by distillation. Thereactions of the active material, moreover, are not those of ozoneor hydrogen peroxide, but those of an organic peroxide.In most cases these peroxide-like substances are very difficult topurify, but analysis indicates that the number of added oxygenatoms is or some multiple of two if auto-oxidation takesplace a t more than one point in the molecule.In the case ofdimethylfulvene a definite dioxide has been isolated.504 6 A. Orhkhov and M. Roger, Zoc. cit. *’ M. Tiffeneau, A. Orekhov, and J. LBvy, Conzpt. rend., 1924, 179, 977;A., 1925, i, 544; J. LBvy and R. Lagrave, ibid., 1925, 180, 1032; A , , i,679.48 C. Englex and W. Wild, Ber., 1897, 30, 1669; A . , 1897, ii, 402; C.Engler and J. Weissberg, ibid., 1898, 31, 3046; A . , 1899, i, 221.40 C. Engler, ibid., 1900, 33, 1090, 1097, 1109; A., 1900, i, 399 et sep.6o C. Engler and W. Frankenstein, ibid., 1901, 34, 2933; A., 1901, i, 657118 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.These facts, and many others,51 are consistent with the Engler-Bach theory that the first stage of auto-oxidation consists in theaddition of molecular oxygen to give a “ moloxide ” (XO,), whichmay either oxidise more of the original substance to the monoxide(XO), or oxidise some other substance (if present) even althoughthis may not be auto-oxidisable in the ordinary sense :X + 0, = XO, (first stage)XO, + A = XO + A 0 (“ activation ” effect).{XO, + X = 2x0 (second stage)In some cases the action can be arrested a t the first stage; inothers the products from both stages are found; again in others 52the second stage follows very rapidly upon the first.These conceptions have been developed to a considerable extentby H.S t a ~ d i n g e r , ~ ~ who formulates the auto-oxidation of ethylenederivatives thus :R,C:CR,0:o + -The scheme is illustrated by reference to the ketens and otherethylenic compounds.The keto-ketens are readily auto-oxidisable, the sensitivitytowards atmospheric oxygen of diphenylketen being comparablewith that of tri~henylmethyl.~~I n general, the primary auto-oxidation products of ketens aretheir moloxides, which are precipitated as polymerides when oxygenis passed into an ethereal solution of the keten a t temperaturesbelow - 2OO.55 Dimethylketen dioxide, the most stable of theseries, is thus obtained as an amorphous powder which is violentlyexplosive. I n ethereal suspension at the ordinary temperaturedecomposition takes place without explosion, giving acetone andcarbon dioxide, a reaction comparable with the well-known divisionof P-lactones,61 A.Klages and S. Heilmsnn, Ber., 1904, 37, 1449; A,, 1904, i, 487;M. Tiffeneau, BUZZ. SOC. chim., 1902, [iii], 27, 1066; A., 1903, i, 81 ; 0. Wnllach,AnnaZen, 1905, 343, 28; A., 1906, i, 194; G. Ciamician and P. Silber, Ber.,1903, 36, 4266; A., 1904, i, 161.62 Ann. Report, 1924, p. 109.63 Ber., 1925, 58, 1075; A., i, 898.54 H. Staudinger, “ Die Ketene,” p. 49.5 5 H. Staudinger, K. Dyckerhoff, H. W. Klever, and L. Ruzicka, Ber.,1925, 58, 1079; A., i, 933ORGANIC CHEMISTRY. 119Diethylketen moloxide is less stable, and undergoes a similardecomposition into diethyl ketone and carbon dioxide. Phenyl-methylketen moloxide is still less stable, and must be prepared at- 80°, since a t higher temperatures it passes into acefophenoneand carbon dioxide.Diphenylketen moloxide is unstable even a tThe peroxidic character of these substances is shown by theirexplosiveness, and by the fact that they readily oxidise potassiumiodide solution. On the other hand, no loss of oxygen to givemonoxides (see below) takes place on thermal decomposition.When oxygen is passed into keten solutions at the ordinarytemperature the moloxide is not obtained, but two types of " second-ary " oxidation products are formed, namely, (a) ketones and carbondioxide,- 80".R,C:CO + 0, -+ R,,CO + CO,,(b) keten monoxides, which, like the dioxides, are obtained inpolymerised forms, although th'eir reactions can be most simplyR,C-CO represented by means of the monomolecular formula, ,o/ .The following table shows how the relative proportion of ketoneand carbon dioxide, obtained by auto-oxidation at the ordinarytemperature, varies with the stability of the moloxide prepared a tlow temperatures :Products of auto-oxidation a t the ordinarytlempera ture.Stability of ( a ) Ketone+carbon ( b ) KhtenKeten.moloxide. dioxide. monoxide.Me,C:CO Stable a t -10" About 85% None obtainedE t2C: CO Rather less stable 9 , 6W/O Small quantityMePhC:CO Stable at -80" 9 ) 30% Larger quantityPh2C:C0 Unstable at - 80" 9 9 15% Main productSince the quantity of ketone and carbon dioxide increases withincreasing stability of the keten moloxide, it is concluded thatthey are formed by the decomposition (thermal division) of thelatter.The variation in the quantity of keten monoxide producedshows that i t cannot be derived from the same proximate source asthe ketone and carbon dioxide, and for this reason the monoxide isregarded as arising from some earlier oxygen-addition productthan the oxide from which the ketone and carbon dioxide are formed.These conclusions, which are consistent with the properties of th120 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.moloxides, are expressed in the general scheme of auto-oxidationgiven above.Diphenylketen monoxide, although polymerised, behaves inmany ways as the a-lactone of benzilic acid. The direction ofaddition of methyl alcohol and aniline is curious, the productsbeing a-methoxydiphenylacetic acid and a-anilinodiphenylaceticacid, respectively, unaccompanied by the expected ester or anilideof benzilic acid.Diphenylethylene 56 yields a moloxide which is highly polymerisedand singularly stable; on heating, however, it breaks down intobenzophenone and formaldehyde :I n this reaction depolymerisation to the labile monomolecularoxide doubtless precedes division into the carbonyl compounds,since the production of benzophenone and formaldehyde during theauto-oxidation of diphenylethylene cannot be attributed to thedecomposition of polymerised moloxide, which is stable unlessheated.0xonides.-By analogy with the mechanism of auto-oxidationit is suggested 57 that the first step in the reaction between ozoneand an unsaturated substance is the formation of a “ molozonide,”corresponding in structure with a moloxide.The molozonide mayeither polymerise (just as the moloxides do), giving ozonides ofhigh molecular weight, such as are obtained from cyclopentene andcyclohexene, or it may isomerise to an “ isoozonide,” to which classthe stable, distillable ozonides, like ethylene ozonide, are assumedto belong, or it may undergo thermal division to give a ketone and aketone peroxide or acid.This view possesses clear advantages over most older viewsregarding the structure of ozonides. If, for instance, the iso-ozonide formula is compared with Harries’s ozonide formula, it isseen that the first is simi1a.r in certain respects to an acetal, whilstthe second represents a glycol peroxide. The latter on reduction6 6 H.Staudinger, Ber., 1925, 58,1075 ; A., i, 898.6 7 Idem, ibid., p. 1088; A., i, 898ORGANIC CHEMISTRY. 121ought, therefore, to give a glycol, whereas the former would beexpected to give the ketonic products actually obtained.R,C:CR, --f R2Q-QR2 --+ R2Q 7R2 R27--QR2 + 0-0:o 0--0 o*o*o/O\~0:o:o Molozonide i8oOzonide Harries's f orrnulrt(an acetal derivative) (a glycol derivative) .1 3.Polymeride R2E + 5R2 R&:O + O:CR2 R2C(OH)*CR2(OH)0 0:o (formed) (not formed) ' R*CO,H (if one R = H)It is noteworthy that the tendency to polymerisation is mostmarked in those cases in which conversion into an isoozonidemight be expected to occur with unusual difficulty owing to theoccurrence of the original double linking in a ring structure.Further,the presence of acetic acid appears to facilitate isomeric change,whereas solvents which tend to favour association cause, in manycases, the formation of highly polymerised substances.The rupture of the carbon chain which, according to this view,takes place when the molozonide undergoes rearrangement maybe compared with the change which occurs when ketone peroxidespass into esters : 581 c-&o:o -+ G"o--c:oMechanism of the Grignard Reaction.Since the classic investigations of P. Barbier and V. Grignard 59the addition between a magnesium alkyl halide and a carbonylcompound has usually been represented thus :the addition product (I) being a halogenomagnesium alkyloxide.Within recent years, however, dissatisfaction with this viewhas been expressed, and alternatives have been suggested.J. vonBraun and G. Kirschbaurn6O proposed an oxonium structure(11) for the addition compound, and J. Meisenheimer and J. Casper 61advanced a " co-ordination formula " (111) with magnesium as thecentral atom. In order to make the co-ordination number equal6* A. v. Baeyer and V. Villiger, Ber., 1899, 32, 3625; 1900, 33, 858; A.,1900, i, 133, 328.sB Compt. rend., 1899,128, 111; A., 1899, i, 323; ibid., 1900,130, 1323; A.,1900, i, 382; and later papers.60 Ber., 1919, 52, 1725; A,, 1920, i, 30.6 1 Ibid., 1921, 54, 1655; A., 1921, i, 654122 ANNUAL REPORTS ON THE PROGRESS OB CHEMISTRY.t o 4, a molecule of ether was included in the complex, but since theether-content of Grignard addition compounds prepared in thatsolvent varies both with the nature of the magnesium alkyl halideand with the carbonyl compound in a manner which is not fullyunderstood, it is simpler to consider the ether-free substances which,as is well known, can be isolated in the solid form.Leaving theether out of formula (111) would, according t o H. Rheinboldt andH. Roleff,Gz give to the magnesium atom the co-ordination number 3.RR”Co>Mg<g, Et20 (111.)Despite these various counter-suggestions, no clear demonstrationhad been given of the necessity for abandoning the previouslyaccepted view, until Rheinboldt and Roleff ingeniously took advantageof the observation made by K.Hess and H. Rheinboldt G3 thatGrignard addition compounds may decompose on heating with theelimination of an olefin and the formation, after addition of water,of a reduction product :[RR’C:O + MgBr*C,H,] ya$ RR’CHoOH + C2H4.It is evident that the normal Grignard reaction between RR”C:Oand R’MgX, leading to RR’R’’C-OH, yields no evidence of any lackof equivalence between R, R’, and R” in the initial addition com-pound, since all these groups are similarly situated in the finalproduct. On the other hand, the side-reaction observed by Hessand Rheinboldt marks off one of these groups from the other two,and can be used to test their equivalence in the compound under-going this decomposition. If, for instance, these compounds be ofthe type represented by formula (I), then the addition productsfrom‘G%>c:O + Mg<g and from ‘63>C:O + Mg<gshould be identical, and the subsequent course of the reaction shouldbe the same in each case; that is to say, the same by-productsshould be obtained, as well as the normal carbinol.This was tested 64 in cases in which R’ was a radical, like iso-butyl, capable of being eliminated as an olefin, and it was foundthat whereas benzaldehyde and magnesium isobutyl bromide gave,in addition to the expected secondary alcohol, a large yield of benzylalcohol, isobutylene behg elinkated,62 Ber., 1924, 57, 1921; A., 1925, i, 6.63 Ibid., 1921,54, 2043; A., 1921, i, 777.41, 2717; A., 1908, i, 881.Compare P.Schorigin, Ber., 1908,64 Ibid., 1924, 57, 1921; A., 1926, i, 6ORGANIC CHEMISTRY.123only the secondary alcohol was obtained when isovaleraldehydeand magnesium phenyl bromide were employed :Further, the bromomagnesium alcoholate, C6H5*CH(OMgBr)-c4H9,corresponding in constitution to formula (I), was prepared directlyfrom phenylisobutylcarbinol and was found to give no isobutyleneon heating, and no benzyl alcohol on subsequent treatment withwater, the original carbinol alone being recovered.From these and similar results, Rheinboldt and Roleff concludethat the initial addition products of magnesium alkyl halides withcarbonyl compounds cannot have a constitution in which the alkylgroup introduced with magnesium is equivalent in position to theothers, and, following Hess and Rheinboldt, they suggest formula (IV).Some such structure may well account for the elimination of theolefin, but, as J.Meisenheimer 65 points out, it is difficult to explainthe normal reaction on the basis of this formula alone. It is there-fore assumed that the original addition compound may undergorearrangement to a halogenomagnesium alkyloxide either with orwithout the elimination of an olefin (V and VI) :Theadoptolefin,J.RR'CH*OHscheme given is Meisenheimer's ; Rheinboldt and Roleffa slightly different interpretation of the elimination of thebut in other respects their conclusions are closely similar.The Metallic Ketyls.This field of investigation, opened up by W. Schlenk and T. Weichlin 1911, has been further explored during the past two years byBlicke and his collaborators, who have published detailed investig-ations of the action of sodium on benzaldehyde and a number ofbenzoic esters.Schlenk and Weickel 66 concluded that the coloured reactive com-pounds obtained previously by E.Beckmann and T. Paul 6' by the6 5 Annalen, 1925, 442, 180; A., i, 527.66 Ber., 1911, 44, 1182; A., 1911, i, 545.6 7 Annalen, 1888, 266, 1 ; A., 1889, 78124 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.action of sodium on benzaldehyde, benzophenone, and various otheraromatic ketones were not, strictly speaki'ng, the sodio-derivativesof glycols,R,C*ONaR,&ONa'2R2C:0 + 2Na +but were tervalent carbon compounds, to which the name " ketyl "was given :R,C:O + Na + R,y*ONa.The evidence in favour of the ketyl structure was originally purelychemical, being based, for instance, on the reactions with oxygen,iodine, and methyl iodide :R2C*o*o*cR2 ++ 2R2C:0 + 2Na0. 2R,b*ONa + 0, -+ h a h aI2R2C1 R,C:O + NaI.2R,C*ONa + I, + bNaR,C(CH,)*ONa Hzox R,C(CH,)*OH { R,CI*ONa -+ --+ R,C:O + NaI2R,&ONa + CH,I 4Later 68 it was shown that the soluble sodium compound of phenylp-diphenylyl ketone had a molecular weight closely correspondingwith the tervalent carbon formula, but, in order to account for thecircumstance that on treatment with water not only the alcohol andketone, but also the corresponding pinacol, may be produced, anequilibrium with the bimolecular form was assumed :R,(?*ONa H,O R29*OH1 HSO I 2R,C*ONa -+ 2R,C*OH - + r R 2 YR,CH*OH.This is also in agreement with the fact that the same sodium com-pound can be obtained from the ketone and from the pinacol by theaction of s0dium.6~The action of sodium on benzoic esters 'O appears to be similarto the above, but the bimolecular sodium compounds, which can beregarded as derived from di-alcoholates of benzil, spontaneously losetwo molecules of sodium alkyloxide, yielding benzil, which may beconverted by the further action of sodium into the disodio-compound68 W.Schlenk and A. Thal, Ber., 1013, 46, 2840; A., 1913, i, 1205.69 S. F. Acree, Amar. Chem. J . , 1003, 29, 588; A., 1903, i, 724.70 F. F. Blicke, J . Amer. Chem. SOC., 1925, 4'7, 229; A , , i, 662ORGANIC CHEMISTRY. 125of stilbenedi01.~1 The latter on treatment with water yieldsbenzoin : 72Phy==yPh +- Phc-GPh0 0 Na ONa ONap , o )PhC(OH):C(OH)Ph + PhCH(OH)*COPh.Similar cha.nges occur in the reaction between sodium andbenzaldehyde. When one atomic proportion of sodium is used inethereal solution, the metal dissolves and a coloured solution isformed, from which the ketyl separates as a deep green precipitateOn addition of water and acid, the green colour is immediatelydischarged and a solution is obtained containing benzyl alcohol,benzaldehyde, benzoic acid, benzyl ether , benzyl benzoate, andbenzoin.73 The first two of these substances are, apparently, thenormal products of the action of water upon the ketyl.The ketylreduces benzaldehyde to benzyl alcohol and is itself transformed intosodium stilbenediol, which is ultimately converted into benzoin inthe manner shown above.The benzyl benzoate is probably formed bythe action of sodium benzyloxide on ben~aldehyde,~~in which reactionbenzyl ether is known to appear as a b y - p r ~ d u c t . ~ ~ The benzylbenzoate may also give rise to sodium stilbenediol and thence tobenzoin :PhCH*OH + Ph*CH2*OH + PhGHO.It is noteworthy that the products obtained from benzaldehydeappear to arise mainly from the monomolecular ketyl, whereas inthe case of benzoic esters the bimolecular compound seems to be theprincipal source of the products obtained.71 H. Staudinger and A. Binkert, Helv. Chim. Acta, 1922, 5, 705; A., 1922,i, 1016; A. Scheuing and A.Hensle, Annalen, 1924,440,172; A , , 1925, i, 27.72 A. Lachman, J . Amer. Chem. SOC., 1924, 46, 708; A., 1924, i, 649.73 F. F. Blicke, ibid., 2560; A., 1925, i, 37.74 L. Claisen, Ber., 1887, 20, 646; A., 1887, 674; C. A. Kohn and WTrantom, J., 1899, 75, 1161.0. Kamm and W. F. Kamm, J . Amer. Pharnb. ASSOC., 1922, 11, 590126 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.An interesting property of the sodium ketyls, which appears tobe general, is their power to combine with another atom of sodium,giving a disodio-compound in which the metallic atom combinedwith carbon is extremely reactive : 76Thus the disodio-compound derived from benzophenone readilycombines with carbon dioxide or bromobenzene, yielding, aftertreatment with water, benzilic acid and triphenylcarbinol, respec-tively.This, no doubt, is the explanation of H. Frey's observationthat benzophenone, bromobenzene (1 mol.), and sodium (2 mols.)react to give an almost quantitative yield of triphenylcarbinol. 77The same end-product is obtained when benzoic esters are treatedwith bromobenzene and an excess of sodium,7s and a similar explan-ation can be given :,,>c:o P11 (2Naj ,Pb>CNa*ONa P h 2 c < g 2 a Ph,C:o~ h T a j Ph,CNa*ONa (P~B$ Ph,C*ONa (H,Oj Ph,C.OH.Derivatives of cycloPropane and cycloButane.Formation by Malonic Ester 8ynthesis.-Attention has often beendirected to the remarkable influence of substituents on ring closure.For example, the condensation of ethyl sodiomalonate with tri-methylene dibromide leads to a cyclobutane ester,79CH2<:2$ + 2CHNa(C02Et), --+ CH,<~~>C(CO,EB),,whereas condensation with ethyl ma'-dibromo- p p-dimethylglutarateyields, not the analogous cyczobutane derivative, but an isomericcydopropane compound :CMe2<:gg::$)g + 2CHNa(CO,R), --tCH*CO,RC0,R) C H (CO,R),'Two causes might be suggested to account for this difference.7 6 W.Schlenk, J. Appenrodt, A. Michael, and A. Thal, Ber., 1914, 47, 486;7 7 Ber., 1895, 28, 2520; A., 1896, i, 99.78 P. Schorigin, Ber., 1907,40,3115; A., 1907, i, 753; F. F. Blicke, J . Amer.Chem. Soc., 1925, 47, 229; A., i, 662.78 W. H. Perkin, jun., J . , 1887, 51, 4.80 W. H. Perkin, jun., and J. F. Thorpe, J., 1901, 79, 729.A . , 1914, i, 396; F. F. Blicke, Zoc.cit.CompareC. K. Ingold and J. F. Thorpe, ibid., 1919,115, 320ORGANIC CHEMISTRY. 127First, the effect of the carbethoxyl groups in increasing the reactivityof the adjacent carbon atoms might favour their direct union byelimination of hydrogen bromide. Secondly, substitution of thegem-dimethyl group would be expected to augment the stability ofthe cyclopropane compound relatively to that of its cyclobutaneisomeride.Apparently both these effects contribute to the differencesobserved, for H. R. Ing and W. H. Perkin 81 have now investigatedthe intermediate case, the condensation of ma'-dibromoglutaricester, in which the carbethoxyl groups are present but the gem-dimethyl substituent is absent, and have observed the simultaneousoccurrence of both cyclopropane and cyclobutane ring formation :CH(C0,R)CH2<CH(C02R) >c (CO,R), 7 (C)CH <CHBr*Co2R + ZCHNa(CO,R),CHBr*CO,RCH*CO,R(A) cH2'(I(C02R)*CH(C0,R)2As would be expected from the great difference in the ease of form-ation of five- and four-membered rings, the corresponding condens-ation of Ex'-dibromoadipic ester proceeds smoothly in one direction,82no cyclobutane derivative accompanying the cyclopentane esterformed :,CHBr *CO,R ,CH*CO,R\ + ZCHNa(CO,R), I_) qH2 C(CO,R), (D) (B) 82 CH\CHBr *CO,RIn the course of this work the interesting fact has been discoveredthat in the ring closures leading to the symmetrical esters (C) and(D), changes of configuration may take place.The dibromo-esters (A) and (B) each contain two equivalent asymmetric carbonatoms, and therefore exist in meso- and racemic modifications.Dur-ing the condensations replacement occurs at each of these carbonatoms, which remain asymmetric and equivalent in the final product.Hence, if no change of configuration took place, the meso-bromo-ester should yield the meso-ring-ester, and the racemic bromo-esterthe racemic ring-ester. The same products would be obtained if a82 W. H. Perkin, jun., and E. Robinson, J., 1921,119,1393 ; A. W. Bernton,J., 1925, 127, 2387.H. R. Ing, and W. H. Perkin, jun., {bid., 1924, 125, 1492128 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.change like the Walden inversion occurred at both asymmetriccarbon atoms. If, however, configurative change occurred at oneasymmetric carbon and not at the other, the meso-bromo-estershould yield the racemic ring-ester and vice versa.Such unsym-metrical inversions occur, because, in the first place, both the puremeso- and the pure racemic dibromoglutaric ester yield mixtures ofthe meso- and racemic ring-esters. Still more remarkable, however,is the fact that a complete inversion takes place in the very smoothcondensation of meso-dibromoadipic ester to give the racemiccyclopentane ester. Apparently the change of configuration doesnot precede the condensation in this case, because the meso-dibromo-ester is stable, and the tendency to isomeric change is in the otherdirection, namely, racemic- meso. The configurations of the ringesters were conclusively proved by the resolution of the racemictribasic acids derived from them on hydrolysis; 83 those of thedibromoglutaric acids appear to follow from their synthesis 84 bythe fission of cyclic compounds; and those of the dibromoadipicacids are established by the resolution of the racemic i~orneride.~~In passing, it may be noted that the cyclopropane ester (E) readilychanges by internal condensation into the dicyclic ketone (F), whichcan be isolated as its sodium compound (G).This is the simplestmember of the five-carbon ring series of compounds in which intra-annular tautomerism has been shown to occur.(F) CH2<s: (c02R)*$?0 CH2<$?(C02R)'R*0Na (G)C(CO,R)*CH-CO,R C( CO,R)*C*CO,RFormation of cycloPropane Cinnpounds by the Action of Alkalison Bromo-acids.-The method of producing cyclopropane compoundsby reactions 86 such asCHBr*C02Et (KOH) CR,<FH*C02H3 CH*CO,H -CHBr*CO,Et WOW c~,<y(OEW'"O2HCH*CO,H + --CR2<CHBrC02Et @toH)has recently been extended to several new cases.Ring closures ofthis character have been shown to be largely influenced by spatialdifferences due to substitution, and the order of facilitation of thereaction is as follows :83 W. H. Perkin, jun., and E. Robinson, loc. cit.; H. R. Ing and W. H.84 J. Thiele, Annalen, 1901, 314, 305; A., 1901, i, 181.85 B. Holmberg and E. Miillcr, Ber., 1925, 58, 1601 ; A., i, 1236.a6 W. H. Perkin, jun., and J. F. Thorpe, J., 1899, 75, 48; 1901, 79, 729.Perkin, jun., Eoc. citORGANIC CHEMISTRY. 129H>C<yMe*CO,H / H>C<QH*C02HH CH*CO,H \ H CH*CO,H H CH*C02H/ cH3>C<7H*C02H and QH2*CH2>c<$!H*C02H\ CH3 CH*CO,H CH,*CH, CH*CO,H/ cH2<CH2*CH2>c<QH*C02H \ FH2*CH2*CH2>c<QH*C02H\ CH2*CH2 CH*CO,H / CH,*CH,*CH, CH*CO,H.In the first of these cases 87 it is assumed, in conformity with otherevidence,88 that the branched chain residue in the glutaric acid has agreater space-filling capacity than the normal acetic acid residue,and thus tends to widen the angle at the central carbon atom :If this be admitted, the whole series falls into line with the require-ments of the spatial hypothesis, with the exception of the cyclo-heptane compounds, the anomalous behaviour of which it seemsimpossible to account for except on the supposition that the cyclo-heptane ring is puckered, or becomes so under the conditions inwhich the cyclopropane ring is formed.89Further evidence of the abnormal influence of the cycloheptanering is derived from the fact that the spiro-compound is definitelyless stable than its cyclohexane analogue, as is shown from a studyof the ring-chain tautomerism exhibited by its hydroxy-derivative.The relative stability of the individuals entering into the system(OH)CO,HR,C<Q CH*C02HStable form-if Balanced action if Stable form-if R, =(R, = C5H,,>) ( R, = Et, or Pra, ) (H,, Me,, or C,H,>)has been shown to be an important criterion of the effect of thesubstituents R, in modifying the stability of the cyclopropane ring,for whilst in the dihydrogen (R, = H2), dimethyl (R, = Me,), andcyclopentane series (R, = C,H,>) the open-chain keto-acid is thestable modification, in the cyclohexane series (R, = C,Hlo> ) thestrain in the three-membered ring is relieved to an extent whichrenders the hydroxy-ring compound the stable isomeride ; inter-8 7 C.K. Ingold, J., 1925,127, 387.8 8 C. K. Ingold and E. A. Perren, ibid., 1921, 119, 1582.8B J. W. Baker and C. K. Ingold, ibid., 1923, 123, 122; H. Meerwein,J . p r . Chem., 1922, 104, 161 ; A., 1923, i, 221 ; H. Meerwein and J. Schafer,ibid., p. 289; A., 1923, i, 324; F. Dickens, L. Horton, and J. F. Thorpe, J . ,1924,125, 1830.REP.-VOL. XXII. 130 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.mediate cases are known (e.g., R, = Et,) in which the two formspossess approximately equal stability.Now, if the cycloheptanering possesses a planar configuration, it should take its normalplace in the series, and its spirocyclopropanol acid should be evenmore stable relatively to its keto-acid than is the case with thecyclohexane compounds. It was found, however, that although thecycloheptane spiro-hydroxy-acid was present in sufficient amountto be isolated (yield l%), the keto-acid was the more stablei n d i v i d ~ a l . ~ ~ These cycloheptane compounds, therefore, closelyresemble their cyclopentane analogues, which contain an almoststrain-free ring, and their behaviour accords with the view that thecycloheptane ring exists in a multiplanar form.A very remarkable series of anoimlous reactions was encounteredby W.Haerdi and J. F. Thorpe 91 when invcstigating the influenceof a single phenyl substituent. The reaction of dibrorno-*p-phenyl-glutaric ester with alcoholic potash procceded normally, giving agood yield of ethoxy-ring ester :but, in the case of the monobromo-compound, the correspondingring -closureCH*CO,HPhCH<&I*C02HPhCH<CHBr*Co2R ---+CH,CO,Rcould not be effected either with potash or with pyridine, owingto the fact that practically quantitative reduction to p-phenyl-glutaric acid (or ester) occurred in the presence of these reagents.This phenomenon has not been encountered before in analogousexperiments with aliphat,ic halogenoglutaric csters, and must beattributed to the presence of the phenyl group.But the mannerin which this group imparts to the bromine atom the type of activityobserved, and why it does so only in the case of the monobromo-ester appear obscure notwithstanding recent discussions regardingsuch phenomena.In view of the fact that a bromine atom in bromocyclopropaneacids is frequently rather difficult to remove, the quantitativereduction by potash of the bromocyclopropane ester formulatedbelow represents another remarkable instance of the influence ofthe phenyl groupg29O J. W. Baker, J . , 1925, 127, 1678.91 Ibid., p. 1237.92 W. Haerdi and J. F. Thorpe, Zoc. citORGANIC CHEMISTRY. 131/ phcH<CH2*C02K CH2*Co2K + 2MeOH+KOBrCH,*CO,MeCH Br*COzMe @os'phcH<CH2-C0,Me '"y.id&p PhCH<CH2*co2Me + Br.PhCH<?Br'Co2Me --+ PhCH< CH*Co2H I + 2MeOH + KOBrCH*CO,Me (3K0g CH-C02HThe Occurrence of Carene and Sy1vestrene.--So few derivativesof cyclopropane have been found in nature that the suggestiong3that the carenes may prove to be widely distributed is of greatinterest.A3-Carene was first isolated by J.L. Simonsen from the essentialoil of Pinus longifolia in 192OJS4 and shortly afterwards the sameinvestigator obtained A4-carene from the oil of AndropogonJwa~ancztsa.~~ On treatment with hydrogen chloride both thesedicyclic terpenes yielded mixtures of dipentene dihydrochloride ands ylvestrene dihydrochloride .sCMe CMe/ \CH CH,CHc$ \CHA3-Carene A4-Carene/ (Ha) \ NCMe CMeCl CMeCl CMe/\\ /CH,c- y H Z vH ,CH2as$ CH, CH*C'<M,Dipentene Sylveetrene Sylveetrene.Dipentene. dihydrochloride.dihydrochloride.Now the recorded occurrence of sylvestrene in nature has alwaysseemed anomalous, since it is the only naturally occurring terpenederived from m-cymene, all other members of the series beingp-cymene derivatives, and it was therefore thought probable 97 that9* B. S. Rao and J. L. Simonsen, J., 1925, 127, 2494.D4 Ibid., 1920, 117, 571.96 Ibid.@' B. S . Rao and J. L. Simonsen, Zoc. cit.95 Ibid., 1922, 121, 2294.Compare Indian Forest Rec., 1924,10, 161 ; A., 1925, i, 1164.E132 ANNUAL REPORTS ON !FHE PROGRESS OF CHEMISTRY.although sylvestrene has been obtained from a considerable numberof natural sources, it might not exist as such in nature, but mightbe formed during the process of purification.Sylvestrene was first isolated from Swedish pine-tar oil, derivedfrom Pinus sylvestris, by A.Atterberg,98 who treated the appropriatefraction of the oil with hydrogen chloride, when sylvestrene dihydro-chloride, m. p. 72", was obtained. All subsequent investigatorsappear to have used this method of isolating sylvestrene fromnatural oils. It is significant that, in the course of his work, A.Atterberg 99 also isolated a hydrochloride of m. p. 50°, which is them. p. of dipentene dihydrochloride, and that this substance wasalso encountered and recognised by J. Bertram and H. Wahlbaumduring the purification of sylvestrene through its dihydrochloride.Moreover, several workers noticed that the most characteristicreaction of sylvestrene, the deep blue colour formed when a dropof concentrated sulphuric acid is added to a solution of the hydro-carbon in acetic anhydride, was not given by those fractions of theoriginal oil from which sylvestrene is obtained ; on the other hand,those fractions gave a colour reaction now known to be characteristicof carene.2An examination of the oil from Swedish Pinus sylvestris showedthat this contained no sylvestrene, although a considerable quantityof A3-carene was .isolated through its sparingly soluble nitrosate.Similarly a sample of oil from Pinus purnilio contained A3-carenebut no sylvestrene.From these results it would appear probable that sylvestrenedoes not occur as such in nature, and that carene, like its cycZo-butane isomeride, pinene, is widely distributed.This proof of the absence of sylvestrene from natural products isof theoretical interest, since it removes the only exception to theview that the isoprene-+geraniol union constitutes the fist step inthe formation of natural terpene structure^.^C.K. INGOLD.PART III.-HETEROCYCLIC DIVISION.THE work to be dealt with this year is greater in quantity and morevaried in character than that of last year, two features which addt o the difliculty of compiling this Report. A natural result of thisBer., 1877, 10, 1203; A , , 1877, i, 79. LOC. cit., p. 1208.1 Arch. Pharm., 1893,231, 301; A., 1893, i, 659.a Idem, ibid.; J. C. Umney, Pharm. J., 1895, 55, 167; A., 1896, i, 380;a B.S. Rao and J. L. Simonsen, Zoc. cit. Compare Ann. Report, 1924, p. 102.Morner, Svensk Farm. !l'ids., 1909, 317, 1913ORGANIC CHEMISTRY. 133is that much work, especially in groups in which there are fewworkers, has had to be left unnoticed, a t any rate for the present.Pyrrole Derivatives.In the previous Report mention was made of the application ofthe Gattermann reaction for the preparation of pyrrole aldehydesand the use of the latter for the synthesis of complex pyrroles.1Further examples of this are the preparation of 3-carbethoxy-2 : 4-dimethylpyrrole-5-vinyl-o-carboxylic acid 2 (I) and a new series oftripyrrylmethane~.~(1.) (11.1Reference may also be made now to a lengthy paper on the use ofmagnesylpyrrole in synthetic work, which will be of great assistanceto workers in this field, not only for its wealth of experimentaldetail, but also for the full bibliography of previous work.4The condensation of substituted pyrroles with formaldehyde inpresence of alkali has been investigated and gives promise of usefuldevelopment.Thus ethyl 2 : 4-dimethylpyrrole-3-carboxylatefurnishes in this way the 5-hydroxymethyl derivative (11), which canbe reduced to the aldehyde or, by the action of alkalis, acids, orboiling water, can be converted into the corresponding dipyrryl-methane.According to H. Fischer and H. Beller, the tetrapyrrylethanesobtainable from 2 : 3-dimethylpyrroles by the methods alreadyreferred to,6 like those furnished by 2 : 4-dimethylpyrroles, arereadily oxidised by ferric chloride to dipyrrylmethenes, in whichrespect both series differ from Etioporphyrin, whence it is concludedthat in this pigment the four pyrrole nuclei are not simply linkedtogether by the group C:C, but contain also two methine linkings.7Numerous papers have appeared on blood and bile pigments, butthese are mainly of biological interest.1 Ann.Reports, 1924, 21, 124.2 W. Kuster, E. Brudi, and S. Koppenhofer, Ber., 1925,58, [BJ, 1014; A., i,3 H. Fischer and M. Heyse, Annalen, 1924, 439, 246; A., 1925, i, 76.4 B. Oddo, Mem. R. Accad. Lincei, 1923, [v], 14, 510; A., 1925, i, 296; seealso Guzzetta, 1925, 55, 235, 242; A., i, 978, and T. N. Godnow and N. A.Naryschkin, Ber., 1925, 58, [B], 2703.5 H. Fischer and C. Nenitzescu, Annaten, 1925, 443, 113; A., i, 834; com-pare V.V. Tschelincev and B. V. Maksorov, J. Buss. Phys. Chern. BOG., 1916,48, 748; A., 1917, i, 164, and A. Einhorn, Annalen, 1905,343,207; A., 1906,i, 245. Ann. Reporta, 1923,20, 138; 1924,21, 124.972.7 Annalen, 1925, 444, 238; A., i, 1333134 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.For reasons already fully discussed,* K. Hess and H. Finkassigned to the alkaloid cuskhygrine formula I. Later experimentsby K. Hess and F, An~elm,~ on the synthesis of one of its degrad-ation products, di-N-methyldi-a-pyrrolidylmethane (11), led to amixture of stereoisomerides, which furnished three methiodides,none of which was identical with either of those obtainable from thedegradation product itself. An attempt has now been made lo toobtain further information on this subject by the reduction ofcuskhygrine. This creates a new asymmetric centre and results inthe formation of two stereoisomeric secondary alcohols, both ofwhich regenerate cuskhygrine on oxidation. A substance of formulaI implies two meso-forms and one racemic form, whilst formula 111,due to Liebermann and Cybulski,ll requires one meso- and one racemicform.The formation of two dihydro-compounds indicates thatcuskhygrine is either the racemic form of I or the meso-form of 111.Exhaustive methFlation of the two dihydrocuskhygrines leadsto n-undecane and n-undecan-c-ol and thus lends support to formula111, since a substance of formula I should yield E-ethylnonane and7-n- butylheptan- @ - 01.Previous work on the oxidation of nicotine has usually led to thesurvival and isolation only of derivatives of the pyridine half of themolecule.P. Karrer and R. Widmer l2 find that on oxidation ofN-methylnicotine (IV) with potassium ferricyanide N-methyl-nicotone (V) is formed, and this on oxidation with chromic acidyields Z-hygric acid, [a]= --80.12", from which is obtainable bymethylation Z-stachydrine (VI) identical with the natural productfrom Stachys tuberifera, or that formed from Z-proline by methyl-ation.It follows from this that Z-proline, Z-stachydrine, and Z-nicotine all8 Ann. Reporb, 1920, 17, 126. 13 Ibid., 1921, 18, 118.10 K. Hess and R. Bappert, Annalen, 1925, 441, 137, 151 ; A., i, 424.11 B~T., 1895, 28, 578; A., 1896, i, 310.12 Helv.Chirn. Acta, 1925, 8, 364; A., i, 1084ORGANIC CHEMISTRY. 135have the same l~vo-c~nfiguration.~~ There still remains to be ex-plained in this group the stereochemical relationship of betonicineto turicine, respectively Z- and d-forms (probably not enantio-morphic) of 4- hydroxystachydrine.14Pyridine Dericatiues.Most of the papers which come within this group relate to thepreparation of comparatively simple derivatives of pyridine, someof which are of importance as primary materials for synthesis, oras possible degradation products from naturally occurring nitro-genous substances, but they do not call for comment here.E. E. Blaise and M. Montagne l5 have found that whilst complex6- diket ones, containing electro- negative groups, undergo enolis-ation on treatment with ammonia and yield dihydropyridines, thesimpler acyclic &diketones furnish cyclohexenones under like con-ditions ; thus yv-nonadione with ammonia yields exclusively2-methyl-3-ethyl-A2-cyclohexen- l-one, but if ammonia is replaced byhydroxylamine hydrochloride, or, better, if the dioxime is heatedwith hydrochloric acid, 2 : 6-diethylpyridine is formed.C.F. H. Allen l6 has found that the &ketonic nitrile (I) formed bythe addition of phenyl styryl ketone to p-nitrophenylacetonitrile isconverted by hydrogen bromide in acetic acid, but not by acetylchloride , into 2 - ke to - 4 : 6-dip henyl- 3 - p - nitro phenylte trahydropyrid-ine (111), which with nitrous acid gives 2-hydroxy-4 : 6-diphenyl-3-p-nitrophenylpyridine.Since water appears to be essential forthe first part of this process, the change is presumed to take placeby the addition of water thus :CHPh*CH,-COPh CHPh*CH,*COPh PhHC*CH=CPhNO,*C,H,*CH-CN N02*C6H4*CH*CO*NH, N02*C,H4*CH*CO*NH(1.1 (11.1 (111.)and this view is supported by the fact that the cyanoacetamideadditive product, COPBCH, CHPh*CH(CN)*CO*NH,, is convertedinto the tetrahydropyridine derivative in presence of either acetylchloride or dimethylaniline.17B. D. Shawls has confirmed his suggestion that pyridine onreduction by sodium and alcohol is first converted into 1 : 4-dihydro-13 Compare Ann. Beports, 1924, 21, 61.14 J. A. Goodson and H. W. B. Clewer, J., 1919,115, 929.l5 Compt. rend., 1925, 180, 1760; A., i, 835; compare E.Knoevenagel,Annalen, 1894, 281, 25; A., 1895, i, 48.16 J . Amer. Chem. Soc., 1925, 47, 1733; A., i, 963; compare Kohler andAllen, ibid., 1924, 46, 1522; A., 1924, i, 855.1' E. P. Kohler and B. 1,. Souther, ihid., 1922, 44, 2903; A,, 1923, i, 243.18 J . , 1925, 127, 215; compare Ann. Reports, 1923,20, 147; 1924, 21, 125*I - I - 1 136 ANNUAL REPORTS ON THE PROURESS OF CHEMISTRY.pyridine, by the isolation of glutardialdehyde, as the dioxime,from the reduction liquor.An interesting modification of Hofmann's reaction has beendescribed. l9 When 1 : 2 : 6-triphenyl-4-piperidone, dissolved inbenzene, is treated with bromine, it is converted into 1 : 3 : 5-tri-bromo-2 : 6-diphenyl- l-bromophenyl-4-piperidone (I), which whenboiled in chloroform yields p - bromoaniline and dibenzylideneacetonedibromide (111).The following explanation of the reaction is given :C,H,Br*NH*CHPh*CHBr*CO*CHBr*CHPhBr with loss Of Brz -+C,H,Br*NH*CHPh*CHBr*CO*CH:CHPh.(11.) C,H4Br*NH2Br*CHPh*CHBr*CO*CH:CHPh with addition Of HBr +(111.1 C6H4Br*NH2,HBr + CHPhBr*CHBr*CO*CH:CHPhIt is assumed that the hydrogen bromide necessary is formed bydecomposition of part of the tribromo-compound (11), and thatHofmann's reaction always proceeds in this manner by formation ofan unsaturated isomeride and ultimate transfer of the negativegroups, resulting in decomposition.Further progress has been made in the chemistry of methylene-dihydropyridines. 2-p-Nitrobenzylpyridine methochloride is con-vertible by the general method into 2-p-nitrobenzylidene-1 -methyl-dihydropyridine. This and its 4-para-isomeride are so unusuallystable that a betaine-like structure involving the nitro-group issuggested, but this idea is scarcely tenable in view of the similarcharacteristics of the non-nitrated compounds.Benzylidene-2-benzylpyridine, C5H4N*CPh:CHPh, obtained by condensing benz-aldehyde with 2-benzylpyridine in presence of zinc chloride, furnishesa methiodide , which, on treatment with alkali, loses benzaldehydeand forms benzylidenemethyldihydropvridine. Stilbazole methiodideis similarly converted into benzaldehyde and 1 -methyl-2-methylene-dihydropyridinea20 The reactions of the methylenedihydropyridines(I) derived from a series of ethyl 4-alkylpyridine-3 : 5-dicarboxylateshave been investigated by 0.Mumm and collaborators.21 Onsuspension in water, they undergo a transformation represented bythe following scheme :Russe Univ. Leningrad, 1924, 55, 397 ; A., 1925, i, 1094.833.127.19 P. Potrenko-Kritschenko and V. B. de Katzman, J . SOC. Phys. Chim.Zo E. Koenigs, K. Kohler, and K. Blindow, Ber., 1925, 58, [B], 933; A., i,21 Annalen, 1925, 443, 272; A., i, 964; compare Ann. Reports, 1924, 21ORGANIC CHEMISTRY. 137NHMe NMeI fl*NHPh- f t . M e-\,=0NMe w.1 (V.) (VI.)The product at stage (V) has been isolated. With phenylhydrazinein dry ether, a similar change takes place and the phenylhydrazone(VI) has been obtained. Reduction of the methides in alcohol,ethyl acetate, or hexane in presence of platinum sponge convertsthem into the corresponding 2-methyl-2 : 3-dihydropyridines.Theauthors represent as follows, the additive compounds 22 formed bythe methides with carbon disulphide (I) and phenylthiocarbimide(11). The reaction with phenylcarbimide proceeds similarly, butco co SHk C 0 2 E t /CH NMe CH/ \PS CH(1.) (11.)the initial products (111) can be isolated in this case and these onboiling with alcohol may furnish dicyclic derivatives (IV) or a mixtureof (IV) and (V). 1 : 4 : 6-Trimethylmethylenedihydropyridine isC02Etfi,+Ph --\A/ CO or NMe \QC< f I k i P hexceptional in combining with 2 mols. of phenylcarbimide, andthe initial additive product yields two dicyclic isomerides (VI, VII).co CH /\/NMe CH NMe CH(111.) PV.) (V.1The commercial possibilities of nicotine as an insecticide are nodoubt in part responsible for the activity in the synthesis of pyridyl-22 Compare Ann.Reports, 1924, 21, 127.E138 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.pyrroles. The initial materials are mucic acid, a convenient sourceof pyrrole which has become available commercially, and a- andy-substituted pyridines, now readily made by the soda,mide reaction.The methods used are essentially those of Pictet and his colleaguesfor the synthesis of nicotyrine and nicotine. All the authors23concerned seem to be agreed that when 2-aminopyridine is dis-tilled with mucic acid the chief product is N - (2‘-pyridyl)pyrrole, butthe results recorded as obtained when this substance is subjected topyrogenic isomerisation are discrepant, although if the reactionproceeds as in Pictet and Crepieux’s case there,appear to be onlytwo possibilities.There was considerable activity during the year in the preparationof condensed pyridines.W. H. Mills, W. H. Palmer, and MissM. G. Tomkinson, in the hope of elucidating the nature of the iso-merism of the 9-acetoxy- and 9-amino-fluorenes (I) obtained by J.Schmidt and co-workers,24 prepared pyridofluorene and certain of itsunsymmetrically substituted derivatives (11). Attempts to resolvethe latter were unsuccessful and thus failed to produce evidencefor the non-coplanar configuration of the fluorene molecule, assumedto be necessary to explain the existence of Schmidt’s i~omerides.~~0. Seide 26 was.unable to convert methyl 2-acetamidopyridine-3-carboxylate (I) into 2 : 4-dihydroxy-1 : 8-naphthyridine (11) by theaction of sodium ethoxide, the only product being the anhydride of2-aminopyridine-3-carboxylic acid (111).C*OH N(1.) (11.) (111.)23 J. P. Wibaut and others, Rec. trav. chim., 1923, 42, 1033; 1924, 43, 526;A., 1923, i, 1232; 1925, i, 75; A. E. Tschitschibabin and I. G. Bylinkin,J . Ruse. Phys. Chem. SOC., 1924, 55, 100; A., 1925, i, 1174; Chem. Fabrikauf Aktien (vorm. E. Schering), D.R.-P. 412168; A., 1925, i, 1329.24 Ber., 1906, 39, 3895; 1908, 41, 1243; A., 1907, i, 43; 1908, i, 415.z5 J., 1924, 126, 2365; compare R. Kuhn and P. Jacob, Ber., 1925, 58,[B], 1432, 2232; A., i, 1260, 1404.26 Ber., 1924, 57, [B], 1806; A., 1925, i, 72; compare L.Schmid and B.Bangler, ibid., 1925, 58, [B], 1071; A., i, 1459ORGANIC CHEMISTRY. 139Similarly, J. M. Gulland and R. Robinson 27 were unable to obtainnaphthyridine derivatives from 3-amino-2-methylcinchoninic acid(IV) by the application of the Camps synthesis.CO-OH CHRiith,28 however, obtained 1 : 8-dihydronaphthyridine (V) by theaction of bromoacetal on 2-amino-3-methylpyridine, but there issome doubt as to the constitution of his initial material, whichdiffers in character from the 2-amino-3-methylpyridine prepared by0. Seide,28 whose data are confirmed by A. E. Tschitschibabin.28From 2-aminopyridine, by the action of bromoacetaldehyde or itsacetals, the latter author obtained pyriminazole (VII) (comnarep.155).N Me Me1(VIII.)Palazzo and Tamburini's 4-phenyl-1 : 8-naphthyrid-2-0ne,~~obtained by the action of sulphuric acid on 2-benzoylacetamido-pyridine (or l-benzoylacetamido-2-pyrimidine), is now shown 30 tobe 4-keto-6-phenyl- 1 : 2-divinylenedihydropyrimidine (VI), ringclosure having occurred at the pyridine N-atom and not at the3-carbon atom.The copyrine synthesis referred to last year 31 has been extendedby Gulland and Robinson 27 to the preparation of 10 : 15-diamino-1 : 8-dimethyldibenzocopyrine (VIII).Quinoline Derivatives.Useful modifications of the Doebner-von Miller quinaldine syn-thesis have been devised independently by c. Rath 32 and by F. A.21 J., 1925,127, 1493; R. Camps, Arch. Pharm., 1899, 237, 659; A., 1900,i, 31.28 Ber., 1925, 58, [B], 346; A., i, 437; 0.Seide, ibid., 1924, 57, [B], 1802;1925, 58, [B], 1733; A., i, 72, 1328; A. E. Tschitschibabin, ibid., pp. 1704,1707; A., i, 1328.29 Atti R. Accad. Lincei, 1911, [v], 20, i, 37; A., 1911, i, 327.0. Seide, Bcr., 1925, 58, [Bj, 352; A., i, 437; compare Ann. Reports,1924, 21, 126, and H. Finger and F. Kraft, Ber., 1924, 57, [B], 1950; A., 1925,i, 73.31 Ann. Reports, 1924, 21, 140 (ref. 68).32 Ber., 1924, 57, [B], 550, 715; A., 1924, i, 555, 667; compare Heller,ibid., p. 764; A., 1924, i, 768.E "140 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Mason.% Both authors prepared 1 : 2-dihydroquinaldine by reac-tions which may be shortly represented by the following linearscheme :CHMeCl*CH,*CH( OEt), + Ph-NH, -+ NHPh*CHMe*CH,*CH( OEt),(11.)In Rath's case (I), ring closure is effected by heating at 260" in asealed tube and in Mason's (11) by treatment with phosphoric oxidein benzene solution; in the latter reaction, hydrochloric acid,acetic acid, or acetic anhydride is ineffective, as is also heatingunder pressure as adopted in (I).Rath has investigated the reactionin a number of other instances with the following results :Amine.o-Toluidine.Methyl-o- toluidine.1 : 2-Dihydroquinoline.o - Aminoprop ylbenzene .Aniline.E th ylaniline .Aniline does notHalogenated product. Substance formed.Bromoacetal. 1 : 2-Dihydroquinoline.8-Bromopr opionace t a1 . 1 -Methyl- 1 : 2 - dihydr o -quinoline.Ethylene chlorohydrin.1-(/3-hydroxyethyl)-l : 2-di-hydroquinoline.quinoline and 3-ethoxp4-ethyl-1 : 2 : 3 : 4-tetra-hydroquinoline.8-Chloropropionacetal. 4-Ethoxytetrahydroquin-oline with some dihydro-Bromoacetal. 1 -Ethylindole with BorneChloroacetal. 4-Ethyl-1 : 2-dihydr0-quinoline.3-etho~y-l-ethyl-2 : 3-di-hydroindole.condense with styryl methyl ketone underDoebner-von Miller conditions, and the best yield (12.8%) of 2-phenyl-4-methylquinoline results when the two reagents are heatedwith a minute quantity of hydrochloric acid in a closed vessel at 135"for 5 hours. A number of substituted 2-phenylquinolines were thusprepared, but no quinoline derivatives could be obtained fromsulphanilic acid, o- and p-aminobenzaldehydes, phenylenediamine,amino-p-cresol, aminosalicylic acid, a-naphthylamine, tetrahydro-p -nap ht hylamine , p - aminoant hr ac ene , or - amino ant hr aquinone ,and only traces from o- and p-nitr~anilines.~~The direct and the indirect conversion of the toluene-p-sulphonylderivative of p-anilinopropionic acid into 4-keto-1 : 2 : 3 : 4-tetra-hydroquinoline (4-dihydroquinolone) by the action of (a) phosphoricChem., 1925, [ii], 111, 65, 83; A., i, 1451,83 J., 1925, 127, 1032.34 H.John and others, J.1462ORGANIC CHEMISTRY. 141oxide and ( b ) phosphoryl chloride followed in each case by hydrolysis,referred to last year,35 have been further investigated s6 by extensionto the corresponding substances,C,H,Me*N( S 0,~C7H7)*CH,~CH,oC0,H,derived from o-, m-, and p-toluidines.The p-toluidine compoundbehaves like its lower homologue, giving with phosphoryl chloridethe 3-chloro-compound (I. S0,X = SO,*C,H,) which, on acid hydro-lysis, yields the corresponding 4-keto-6-methyl-1 : 2 : 3 : 4-tetra-hydroquinoline and on boiling with methyl-alcoholic potassiumhydroxide is converted into 4-methoxy-6-methylquinoline (11)..' co(1.1 (11.) (111.)In the case of the o-toluidine derivative none of the 3-chloro-compound is formed and only a little of the 4-keto-8-methyl-1 : 2 : 3 :4-tetrahydroquinoline and its toluene-p-sulphonyl derivative (111).The latter is anomalous in behaviour and on boiling with acids suffersring scission, producing o-toluidine and p-o-toluidinopropionic acid.With the m-isomeride, the results are like those with the lowerhomologue, but two 3-chloro-derivatives (IV) and (V) are formed,(IV.) (V.) (VI.1both of which undergo hydrolysis and lose chlorine on boiling withhydrochloric acid, yielding the 4-keto-5- and -7-methyltetrahydro-quinolines, respectively.When, in place of the toluidines, p-anisidine and p-phenetidinewere used, the action proceeded as in the case of aniline and p-tolui-dine, but the amount of 3-chloro-derivatives formed in these caseswas small; thus p-anisidine gave 10% of the chloro-product, therest being the toluene-p-snlphonyl-6-methoxyketotetrahydro-quinoline (VI) .An attempt to extend this reaction to the preparation of 4-keto-tetrahydroisoquinoline derivatives from toluene-p-sulphonyl-benzylaminoacetic acid, CH,Ph*N( SO,X)*CH,*CO,H, was un-successful.Ann.Reports, 1924, 21, 129.86 G. R. Clemo and W. H. Perkin, jun., J., 1926, 127, 2297142 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.On treatment with sodamide in presence of xylene, quinolineyields 2-aminoquinoline in about 40% yield, but the reactionproceeds less smoothly than with pyridine. On nitration, Z-amino-quinoline furnishes a stable 2-nitroaminoquinoline, which is con-verted by sulphuric acid a t 130" into 6-nitro-2-aminoquinoline,and from 4-aminoquinoline a 6-nitro-derivative is similarly obtain-able.37 No evidence was obtained of the nitro-group remaining inthe pyridine ring as it does when nitroaminopyridines are isomerisedin like manner.Arising out of Spath's synthesis of the angostura alkaloids,38J.Roger and co-workers find that, when 2- and 3-methoxyquin-aldines condense with aromatic aldehydes, the products do not formcrystalline salts, but this is not the case when the methoxyl groupis in the 4-position or in the benzene n~cleus.3~ With 2-methoxy-lepidine, demethylation occurs and condensation products of thehydroxy-base are formed, which also yield amorphous salts. Un-methylated hydroxyquinaldines and hydroxyaldehydes impede orprevent condensation; thus in Spath and Brunner's synthesis ofcusparine 4o no condensation takes place if 4-hydroxy-%methyl-quinoline is substituted for 4-methoxy-2-methylquinoline or ifsalicylaldehyde is employed in place of piperonalHydrogen halide can conceivably be eliminated from 4-aminoquin-aldinium salts (I) in two ways, wix., with the formation of an imino-base (11) or a methylene base (111), and the latter is considered theMPh NHPh NHPh/\/\#Me\/ \/ NMe(11.) (1.1 (111.)more probable ; thus 4-anilinoquinaldine methiodide (I) , on warmingwith aqueous sodium hydroxide, yields a yellow base, which is re-garded as 4- anilino - 1 - met h y 1- 2 -met h y lene - 1 : 2 - di hy dr oquinoline .The same authors show that 4-chloroquinaldine methiodide withsodium carbonate or ammonia, in presence of alcohol, yields a violetsolution, which slowly deposits steel-blue crystals of a dye,C,,H,&&lI.This has the properties of an isocyanine and isbelieved to be formed in the following way :A.E. Tschitschibabin and otherg, Ber., 1925, 58, [B], 803; A., i, 838.38 Ann. ReportP, 1924, 21, 131.39 J . pr. Chem., 1925, [iii], 109, 88; 110, 86; A., i, 432, 974; compare40 Ber., 1924, 57, [B], 1243; A., 1924, i, 1226.4 1 0. Fischer, E. Diepolder, and E. Wolfel, J. pr. Chern., 1925, [ii], 109, 59;E. Spath and H. Eberstaller, Ber.. 1924, 57, [B], 1687; A., 1924, i, 1335.A., i, 438ORGANIC CHEMISTRY. 143The same dye was probably obtained by Friedel by the action ofphosphoryl chloride on acetomethylanilide. In this case, it issuggested that the dichloro-derivative, NMePh*CCl,Me, first formedcondenses with itself , giving the productNMePh*CMe:CH*CCl,*NMePh,HCl,from which, by ring closure with loss of methylaniline, 4-chloro-quinaldine is formed.The products isolated from the dye mother-liquors confirm this view of the mechanism of the reaction.42The idea that the enhanced reactivity characteristic of methylgroups adjacent to the nitrogen atom in heterocyclic bases might bedue to the capacity of the system -N=CMe- to pass into the system-NH*C(:CH,)- was raised by W. H. Mills and J. L. B. Smith threeyears and has now been subjected to detailed experimentalinvestigation by W. H. Mills and R. Raper.44 The reactivity isgreater in the quaternary salts than in the bases themselves, and thecondensations which result from this enhanced reactivity are broughtabout in presence of strong bases such as piperidine. It is supposed,therefore, that in a solution containing quinaldine ethiodide, piper-idine as a condensing agent, and a reactive substance of the typeX:O such as benzaldehyde, stage I of the reaction consists in theremoval of hydrogen iodide as piperidine hydriodide, with theformation of some methylene base, and stage I1 in the condensationof themethylene base with XI0 to form anintermediate basic productwhich then removes hydrogen iodide from piperidine hydriodide,regenerating piperidine and forming the new quaternary salt :42 0.Fischer, A. Muller, and A. Vilsmeier, J. pr. Chem., 1925, [ii], 109, 69;A., i, 439; compare C. Friedel, BUZZ. SOC. chim., 1894, [3], 11, 1027; A.,1895, i, 423; also A. Kaufmann and E. Vonderwahl, Ber., 1912, 45, 1404;A., 1912, i, 502.43 Ann. Reports, 1922, 19, 156.44 J., 1925, 127, 2466; compare Vongerichten and Hofchen, Ber., 1908, 41,3054; A., 1908,i, 914, and Ktinig, ibid., 1922, 55, 3301 ; A., 1922, i, 1188144 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The possibility of this mechanism in the case of the condensation ofquinaldinium salts with aldehydes and with nitroso-compounds hasbeen demonstrated by the isolation in a typical case of each inter-mediate compound or of a derivative, which leaves little doubt as tothe nature of the reaction.A series of carbocyanines (I) has been reduced to the correspondingmethylenediquinaldine (11) dialkyliodides, further demonstratingthe relationship already suggested 45 as existing between them.CsH6NR:CH*CH:CHoC,H6NR --3 C,H6NR*CH2*CH2CH2*C,H,NR(1.) (11.)The synthesis of compounds allied to the cinchona alkaloids hasbeen continued, but the products are of biological rather than newchemical interest.46 There has been a certain renewal of interest inthe cinchona alkaloids themselves. Quinotoxine oxime has beenprepared and reduced to arninoquin~toxine.~~ Attempts to intro-duce an amino-group into the vinyl side chain of quinine by directmethods were unsuccessful, but phthalylamido- and benzenesulphon-amido-derivatives of quinine were made by treating quinine chloridewith alkali derivatives of phthalimide and benzenesulphonamide,respectively.The acyl groups were removed with difficulty, butsome aminoquinine sulphgte was obtained and converted into aquaternary base, C,oH230N2*NMe,0H, which was isolated as thepicrate,48 An interesting series of copper derivatives of quinine hasalso been described.4sWhen the phenolic hydroxyl group in cupreine is methylated,quinine is formed, but the latter on demethylation yields apoquininein place of cupreine; hydroquinine on the contrary yields hydro-cupreine.The difference between apoquinine and cupreine is there-fore probably connected with the vinyl group in quinine, and in con-firmation of that view it has now been shown that apoquinine,unlike cupreine, is not hydrogenated in presence of nickel and therelationship between the two is probably not stereochemical.50p-isoQuinineis stated to be S-ethylidene-8-quinuclidyl-(6’-methoxy-4’-quinolyl)methan01.5~ Like quinine, it is convertible, by methodsp6 (Miss) F. M.Hamer, J., 1925, 127, 211.‘13 L. Ruzicka, C. F. Seidel, and F. Liebl, Helu. Chim. Acta, 1924, 7, 995;47 S. Friinkel and N. Diamant, Ber., 1925, 58, [B], 554; A., i, 674.A,, 1925, i, 289.S. FrLinkel, C. Tritt, M. Mehrer, and 0. Herschmann, ibid., p. 544;A., i, 573.48 F. Erben, ibid., p. 468; A , , i, 573.6o G. Giemsa and K. Bonath, ibid., p. 87 ; A., i, 291 ; compare S. Friinkeland C. Buhlea, ibid., p. 559; A., i, 573.61 J. Suszko, Rocz. Chem., 1925, 5, 358; A., i, 1448; compare Lippmannand Fleissner, Monatsh., 1891, 12, 332; 1893, 14, 554; A . , 18!)2, i, 82; 1893,i, 738; Bottcher, ibid., 1911, 32, 793; A,, 1911, i, 1011ORGANIC CHEMISTRY. 145that are virtually standardised for this series of alkaloids,52 into (1) aquinotoxine, which in this case is p-(3-ethylidene-Li-piperidyl)ethyl6'-methoxyquinolyl ketone and (2) a N-methylquinotoxine.Niquine, C1SH,402N,, obtained as a by-product in the preparationof p-isoquinine, is a secondary-tertiary base, possesses one ethyleniclinking, and probably a free hydroxyl group.53isoQuinoline Derivatives.Work in this group has as usual been almost entirely confined tothe isoquinoline alkaloids.When papaverine (I) or N-methyl-papaverinium salts are reduced by tin and hydrochloric acid, thereis produced, in addition to the tetrahydro-derivatives (11; R = Hor Me) expected, a small amount of the 2 : 4-dihydro-derivatives(111), pavine and N-methylpavine :It has now been shown 54 that isoquinoline, 1 -benzylisoquinoheor its methiodide, and 6 : 7-dimethoxyisoquinoline or its methiodide,are all reduced, in some instances almost quantitatively, to the tetra-hydro-derivatives and no reduction product of the pavine type wasobtained.The formation of the latter in the case of papaverheis therefore not due either to the presence of the two methoxylgroups in the isoquinoline nucleus, or to the attachment of thebenzyl group in position 1.The parent substances of the alkaloids berberine and papaverineare represented by formuh (IV) and (V) and the names "proto-papaverine " and '' protoberberine " have been suggested for them,to simplify the nomenclature of a number of synthetic bases of thistype, which have been prepared.55CH2 0 O/\/\CH,/'h/h/ / H2C<O! I IN'/" 0 CH,1:; 1 17 6CH, I(-jH -/-\ \9/vw\6/ ? /-\I (*)2 q 6 2 I CJ32 CH, ,ow.1 (v.) OH (VI.) -In 1913, H. Decker and his colleagues 56 described " l-piperonyl-norhydrastinine," to which they assigned formula (VI), as being62 See Ann.Reporb, 1918,15, 113; 1920,17, 117.69 Compare Ann. Reports, 1924, 21, 132.64 R. Forsyth, C. 'I. Kelly, and F. L. Pyman, J., 1925, 127, 1669.66 J. S. Buck, W. H. Perkin, jun., and T. S. Stevens, ibid., p. 1462.b0 Annalen, 1913,385,299; A., 1913, i, 289146 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.produced by the action of phosphoryl chloride in toluene on homo-piperonoylhomopiperonylamine. Repetition of this experimenthas resulted in the isolation of a different product, 6 : 7 : 3’ : 4’-bismethylenedioxy-3 : 4-dihydroprotopapaverine, to which formula(VI) is correctly assigned.This substance, like other l-benzyl-dihydroisoquinolines, is readily oxidised on exposure to air to the9-keto-derivative, which has the properties of Decker’s substance.55By the insertion of a %H,- linking between positions 2 and 2’ or2 and 6’ in protopapaverine (IV), protoberberine (V) can be pro-duced. It is probably carbon atom 6’ which reacts in preference to2’, and when the benzyl group is substituted in the nucleus thisresults in the production of the pseudo-series of alkaloids, $-ber-berine, $-protopine (VII), etc.,57 and it is probably this series towhich the following substances belong.The 6 : 7 : 3‘ : 4’-bismefhylenedioxy-3 : 4-dihydroprotopapaverine(VI) referred to above, on reduction yields the corresponding tetra-hydro-compound, which on condensation with formaldehyde furnishes2 : 3 : 10 : 11-bismethylenedioxyttetrahydroprotoberberine (VIII).The latter is oxidised in the normal way by iodine to the corre-sponding protoberberinium iodide, from which, via the chloride, bythe action of potassium hydroxide solution, the correspondingoxyprotoberberine and dihydroprotoberberine are obtainable 55 inthe same manner as with berberinium chloride, where the analogousproducts are oxyberberine and dihydroberberine.0-ICH,The work on berberine referred to last year 5’ has made it necessaryto find a new synthetical proof of the constitution of berberine.This has been achieved by using the p-piperonylamide of meconin-carboxylic acid (IX), which on prolonged treatment with phosphorylchloride gave, in a preliminary experiment, dioxyberberine (X) and,5 7 Ann.Reports, 1924, 21, 134ORGANIC CHEMISTRY. 147in further trials with larger quantities, oxyberberine (XI) via a,product, provisionally represented by formula (XII), which onreduction with zinc dust in boiling acetic acid, furnished oxyber-berine (XI), probably through (XIII) as an intermediary.CH(XII.)CO CH,Although a full explanation of the reactions involved cannot yetbe given, this synthesis establishes the accuracy of the formulaassigned to oxyberberine on many points and in particular leavesno doubt as to the position of the methoxyl groups. Oxyberberineon elec tr ol ytic reduction yields tetra hydro berb erine , from whichberberine can be prepared, and ,consequently the synthesis confirmsthe formulae assigned to berberine and the alkaloids canadine,palmatine, etc., derivable from it.58Among other attempts to synthesise berberine reference may bemade to one having veratrylnorhydrohydrastinine (XIV) as astarting point.59 It has been shown already that when this sub-stance is treated with formaldehyde and hydrochloric acid, inter-action occurs with the 6’- instead of the 2’- carbon atom and tetra-hydro-q-berberine (XV) results.When the 6’-carbon atom isblocked by a substituent, a nitro-group or a bromine atom, to forceinteraction with the 2’-carbon atom, condensation occurs but inneither case was the expected tetrahydroberberine derivative (XVI)formed.CH, CH,IN \/\A \/\/\ \/\/ YHO / /\CHa O/\/\CH, ()/\AHZC<OI I INH H,C<*I 1 IN H,C<OICH CH, VH CH,/I\ 10’ \/\ \p\OMe(XV.) CH, I (XVI.) bH2 I (XIV.) CH,113‘ r’IOMe$$Me (,!OMe v7 OMeIn the course of this work, it was noted that tetrahydroberberinereadily nitrates in position 6’ (XVI), whilst tetrahydro-$-berberine(XV) does not nitrate but is oxidised by nitric acid.In similar6 8 W. H. Perkin, jun., J. N. RLy, and R. Robinson, J., 1925, 227, 740;compare E. Spiith andH. Quietensky, Ber., 1925,58, [B], 2267; A., 1926, A, 82.69 R. D. Haworth and W. H. Perkin, jun., J., 1925,127, 1448148 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.attempts to use 7-demethylomethylpapaverinol (XVII) as a startingpoint for the synthesis of corydaline, only a +-corydaline derivative,7-demethylo -+-corydaline (XVIII), resulted.60CH2 C332I INCH CH2YHMe MeOH(,!,\/ OMeI lOMe(XVII.) 7 * O H(XVIII.) \/ I )OMeOMe\/OMeCorydaline is the principal alkaloid found in the tubers of CorydaZistuberosa, in which it occurs associated with a dozen or more otheralkaloids, on which much work has been expended and to all ofwhich constitutional formulze have now been assigned.The leastknown members of this series, corycavidine, C2,H2,0,N, cory-cavamine, C2,H210,N, and corycavine, C2,H2,05N, form a sub-group of closely related bases.for cory-cavine (11) and it is now shown62 that the other two bases are ofsimilar constitution ; corycavamine is represented as the keto-formof corycavine, since it is converted into that substance by heating a tA protopine (I) type of formula has been suggested(I.) Protopine (enol form).(11.) Corycavine(enol-form). (keto -f orm) .its melting point, and both alkaloids on treatment with methyliodide yield the same methine base, whilst corycavidine differs fromcorycavine in having the dioxymethylene group in ring A (formula11) replaced by two methoxyl groups.The preliminary observations 63 made on corycavidine are all in60 R. D. Haworthand W. H. Perkin, jun., J., 1925, 127, 1453.61 J. Gadarner and F. v. Bruchhausen, Arch. Pharm., 1922,280, 113.63 J. Gadamer, ibid., 1911, 249, 30; A,, 1911, i, 318.F. v. Bruchhausen, ibid., 1925, 283, 570ORGANIC CHEMISTRY. 149harmony with this view of its constitution, and, like other alkaloidsof similar constitution, the natural d-form (m.p. 212") changes intoan inactive form (m. p. 193") on the application of heat. The newdata brought forward may be summarised thus. Acetic anhydrideconverted the base mainly into the inactive form, but also producedsome N-acetyl derivative and a small amount of a yellowish-redquaternary base, and phosphoryl chloride, which converts cory-cavine quantitatively into the corresponding quaternary base, onlyacted on corycavidine a t temperatures high enough to produceaction in the dioxymethylene group. Reduction of the methylatedproduct gave an optically active tetrahydromethylcorycavidine,which was converted into an inactive anhydro-base by acetylchloride; this is assumed to be due to the presence of the group*CH,*CH(OH)*. Oxidation of this anhydro-base furnished methyl-acetoveratrone (IV) ; methylveratric acid (V) ; a nitrogen-freesubstance, m.p. 243", for which a formula derived from (VI) by thereplacement of the chain *CH,*CH,*NMe, by a carboxyl group isproposed ; N-methylhydrastinine (VII), also obtained in theoxidation of anhydroprotopine ; and the acid (VIII) correspondingto (VII).CH,*CH,*NHMe, 1 (VIII.)O/\/H2C<Ol I\/\co--o \,\/\ CH2-CH2*NMe*CH \/ CH,eCR,*NMe,CHqG) f- PI I V .\/PI/\CH (oH)-cHM~/\/ /\co CHMe/\m.1 (X-1From these, the structure (VI) representing anhydromethylcory-cavidine is built up and from this that of tetrahydromethylcory-cavidine, represented by the condensed formula (IX), in which P andVe represent the piperonyl and veratryl rings, respectively, and soback to corycavidine (X). The validity of the formula is supportedby a number of confirmatory data.Two other minor corydalis alkaloids, corybulbine and isocory150 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.bulbine, C2,H,,04N, are both convertible into corydaline, C,2H2,O4N,by nascent diazomethane, and all three alkaloids yield the sameapocorydaline when boiled with hydriodic acid, so that the twominor alkaloids can only differ from each other in the position of aphenolic hydroxyl group, and from corydaline in the replacementof a methoxyl by a hydroxyl group, Both corybulbine and iso-corybulbine yield ethyl ethers, which on drastic oxidation furnishthe methyl ethyl ether of nor-m-hemipinic acid, so that in bothcases the -OH group must be in ring A (I, 11, 111).This acid hasbeen synthesised from (a) 3-methoxy-4-ethoxybenzaldehyde and(6) 4-methoxy-3-ethoxybenzaldehyde by methods involving ringclosure to the corresponding dihydroisoquinoline and oxidation ofthis to the required acid, which is identical in both cases. Further,on gentle oxidation the two ethyl ethers yield homologues ofcorydaldine :corybulbine--+ 7-methoxy-6-ethoxy- l-keto-1 : 2 : 3 : 4-tetrahydroisoquinolinei~ocorybulbine+6-methoxy-7-ethoxy-l-keto-l: 2 : 3 : 4-tetrahydroieoquinolinecorydaline _3 6 : 7-dimethoxy-l-keto-1 : 2 : 3 : 4-tetrahydroisoquinoline(corydaldine)Both have been synthesised and shown to yield the samemethyl ethyl ether of nor-m-hemipinic acid on further oxidation.The relationship of the three alkaloids must therefore be as follows :This method has also been used to determine the position of the freehydroxyl group in corypalmine, C,,H,,O,N, another of the minoralkaloids of corydalis, which is known to yield d-tetrahydropal-matine, C,,H,,O,N, on rnethylati~n.~~ The ethyl ether of cory-palmine on oxidation with cold alkaline permanganate yields7-methoxy - 6 - ethoxy - 1 - keto - 1 : 2 : 3 : 4 - tetrahydroisoquinoline,whence it is clear that the hydroxyl group must be in position 6 inthe upper isoquinoline nucleus as in formula I1 (below) forjatrorrhizine and that corypalmine is in fact d-tetrahydrojatror-rhizine.64 E.Spiith and A. Dobrowsky, Ber., 1925, 58, [BJ, 1274; A., i, 1085;66 E. Spiith and E. Mosettig, Ber., 1925, 58, [B], 2133; A , i, 1447.compare F. v. Bruchhausen and K. Saway, A~ch. Pharm., 1925, 263, 602ORGANIC CHEMISTRY. 151By the same method, described above, it has been shown66that palmatine (I) is the methyl ether of jatrorrhizine (11), with whichit occurs in Calumba root, and that the free hydroxyl group in thelatter base occupies position 6 in the upper isoquinoline nucleus (11).Feist's columbamine from the same source is shown to be mainlypalmatine, but the isolation of a third alkaloid is foreshadowed forwhich this name is reserved. The constitution of palmatine hasalready been established by its synthesis from berberine,67 fromwhich it differs only in having a dioxymethylene group in place oftwo methoxyl groups, but the difficulty connected with the supposedsynthesis of berberine referred to in last year's Report 68 has ledto repetition of the work.69 This time berberine itself was used asthe starting point in place of tetrahydroberberine and the eliminationof the dioxymethylene group was effected by the use of hydro-chloric acid and phloroglucinol.In this way, the phenolic base(111), in which the two hydroxyl groups replace the dioxymethylenegroup of berberine, was produced, which on methylation furnishedsome palmatine (I) and also some jatrorrhizine (11).&Dieentrine, which occurs in Dicentra spp. along with protopine,tetrahydropalmatine, and sanguinarine (now believed to be amixture of chelerythrine and dehydrochelidonine), is regarded byGadamer 70 as having formula (11) and belonging to the phenanth-renoisoquinoline group recently re-named the aporphine group (seebelow).dl-Dicentrine has now been synthesised 71 from l-veratryl-hydrohydrastinine by converting this into the g'-nitro-derivative anddiazotising the corresponding 6'-amino-compound (I) in presence ofcopper powder, a method due to P ~ c h o r r . ~ ~ Dicentra thereforecontains alkaloids of both the diisoquinoline type (protopine andtetrahydropalmatine) and the phenanthrenoisoquinoline type(dicentrine, chelerythrine, and dehydrochelidonine) .E. Spiith and R. Duschinsky, Ber., 1925,58, [B], p. 1939; A., i, 1313;compare K.Feist and G. 1,. Dschu, Arch. Pharm., 1925,263,294; A., i, 830.6' E. Spath, Ber., 1921, 54, 3064; A., 1922, i, 166.BE Ann. Reports, 1924, 21, 133.'* Arch. Pham., 1911, 249, 680; A., 1912, i, 48.72 Ber., 1904, 37, 1926; A., 1904, i, 612.E. Spiith and H. Quietensky, Ber., 1925, 58, [BJ, 2267 ; A , , 1926, A, 88.R. D. Haworth, W. H. Perkin, jun., and J. Rankin, J., 1925, 127, 2018152 ANNUAL REPORTS ONCHH,C I NMe!l!HE PROGRESS OF CHEMISTRY.CH, NMeTo the account of the chelidonium alkaloids given last yearthere is only to be added a reference to the synthesisof aporphine(V), regarded as the parent of the series.73 For this synthesis,Pschorr's method (see above) was applied to l-o-nitrobenzyl-2-methyl-1 : 2-dihydroisoquinoline (111), obtained by condensingo-nitrotoluene with the +basic form of N-methylisoquinoliniumhydroxide.As would be expected, on " exhaustive methylation ''aporphine yields 1-vinylphenanthrene (VI) and trimethylamine.(111.) w.1 (V. 1 (VI. 1The most difficult group of the isoquinohe alkaIoids-morphine,codeine and thebaine-has also received a, considerable amount ofattention this year,74 but as this work seems to be still in activeprogress it may be more convenient to deal with it later.Among the minor alkaloids of opium it may be mentioned thattritopine 75 has now been shown to be identical with laudanidine.The latter, as was expected, proves to be the Zmvo-form oflaudanine .76Indole Derivatives.It has now been found that indole on complete hydrogenationat 225" in presence of nickel yields o-ethylcyclohexylamine, and not7* J.Gadamer, M. Oberlh, and A. Schoeler, Arch. P h m . , 1925, 268, 81 ;A,, i, 576.74 H. Wieland and others, Annalen, 1923, 433,267; A., 1923, i, 1222; ibid.,1925,444, 69; A., i, 1090; Ber., 1925,58, [B], 2000; A., i, 1448; E. Speyerand others, Annalen, 1924, 438, 34; A., 1925, i, 59; Ber., 1926, 58, [B], 1110,1113, 1117, 1120, 1125; A., i, 961, 962.75 E. Spath and R. Seka, Ber., 1925,58, [B], 1272; A., i, 1093.76 E. Spiith and E. Bernhauer, ;bid., p. 200; A . i, 294ORGANIC CHEMISTRY. 153octahydroindole as previously supposed, but the latter is producedby hydrogenation of indole a t atmospheric temperature in presenceof spongy platin~m.7~ The conclusion previously reached regardingthe influence of alkyl substituents is therefore modified and is nowstated in the form that the stability of the pyrrolidine ring in dicyclicperhydroindole bases is increased by the presence of alkyl substitu-ents, especially when these are near the nitrogen atom.Thus2-methylindole yields the octahydro-derivative a t 200" and onlyat 240-250' does scission of the ring occur, producing o-propyl-cyclohexylamine. 1 : 2-Dimethylindole gives the fully hydrogenatedproduct even at 240°.78The introduction of a positive cyano-group into the benzene ringof indolecarboxylic acid lowers the reactivity of the hydrogen atomsof the pyrrole ring. Thus the condensation product of 6-cyano-indolecarboxylic acid with aminodimethylacetal yields neither anindolediazine nor a carboline.79The investigation of physostigmine, C,,H,,O,N,, the principalalkaloid of Calabar bean, has reached a stage at which a constitu-tional formula can be assigned to it with a fair degree of certainty.80aOn hydrolysis, it yields carbon dioxide, methylamine, and eseroline,CI3H, 80N2, and the latter regenerates physostigmine on treatmentwith methylcarbimide, so that physostigmine must be the methyl-carbamido-derivative of eseroline. The latter furnishes an ethylether, eserethole, the methiodide of which on distillation furnishesphysostigmol ethyl ether. The latter has been synthesised andshown to be 5-ethoxy-1 : 3-dimethylindole *1 (I). This groupingmust also be present in eserethole, and with the replacement ofEtO- by HO-, in eseroline.The problem of formulating these tworesolves itself into ascertaining the manner in which the rest of themolecule (C3H7N) is attached. It was already known that the7 7 R. Willstlitter, F. Seitz, and J. von Braun, Ber., 1925,58, [B], 385; A,, i,428; compare Ann. Repo~ts, 1924,21,139; and R. Willstiitter and D. Jaquet,ibid., 1918, 51, 767; A., 1918, i, 391.78 J. von Braun and 0. Bayer, {bid., 1925, 58, [B], 387; A., i, 428.7s W. 0. Kermack, J., 1924, 125, 2285; compare Ann. Reports, 1924, 21,eoclA. H. Salway, J., 1912,101, 978; 1913,103, 351.81 Ann. Reports, 1924, 21, 143; compare E. Spiith and 0. Brunner, Bm.,139.1925, 58, [B], 618; A., i, 574154 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.nitrogen atom in this residue was tertiary and was present as:NMe,soc so that the expression can reasonably be extended thus :-CH2*CH2*NMe, which clearly implies a pyrroline ring as in (11)to represent eseroline, whilst physostigmine itself is eseroline withthe hydrogen of the hydroxyl group replaced by the methylcarb-amido- group, NHMeOCO 0.82Eserethole (I1 with EtO in place of KO) on reduction furnishesdihydroeserethole (111) and with this change a tertiary nitrogenbecomes secondary, implying the opening of the pyrroline ring as in(111).A study of the methylation products of this substance and otherallied derivatives led M. Polonovski and M. Polonovski S3a toEtO~\-6Me*CH,*CH2*NHMe EtO’>d)CHzCH,I II I \ / \ / \ F H 2 ( (IV.) NMeNMe\ \ f v C H 2(111.1 NMesuppose that in eserethole, and consequently in eseroline andphysostigmine, the chain beyond the asterisked carbon atom in(111) was unbranched and formed a N-methylpiperidine ring as in(IV), which on this view represents eserethole.The ready form-ation of 5-ethoxy-1 : 3-dimethylindole from eserethole referred toabove, however, clearly demonstrates the presence of a methylgroup as in (11) at position 3, and these authors have now acceptedStedman and Barger’s formula. Further evidence for the latterhas been obtained in various ways,82 for example, when eseretholemethiodide (V) is treated with alkali the methohydroxide (VI) firstformed undergoes tautomeric modification to eseretholemethine(VII), which is re-converted into the methiodide by hydriodic acid.2 CH2/\ alkali --?Me QH2 -+ -?Me YHz -+ - Me*CH2*CH,*NMe2--C‘H-NMe,I -CH--NMe,*OH -8HoOH(V.1 (VI.1 (VII.)The methine on oxidation by potassium ferricyanide or ammonia-cal silver nitrate in alcohol, behaves in a manner recalling thesob F.Straus, Annalen, 1913, 401, 350; 1915, 406, 332; A., 1914, i, 78;8Oc M. and M. Polonovski, BUZZ. SOC. chim., 1918, [iv], 23, 336, 356; 1923,82 E. Stedman and G. Barger, J., 1925, 127, 247; compare J., 1923, 123,BuW. SOC. chim., 1924, [iv], 35, 1492; A., 1925, i, 151; compare A.,1915, i, 448.[iv], 33, 970, 977; A., 1918, i, 504, 505; 1923, i, 940.758; 1924,125, 1373.1924, i, 980, 1093, 1094ORGANIC CHEMISTRY. 155oxidation of 1 : 3 : 3-trimethyl-2-indolinol to the correspondingindolin~ne,~~ and a compound, to which formula (VIII) is ascribed,is produced.The latter on exhaustive methylation yields trimethyl-amine, giving the unsaturated substance (IX) which is almost devoidof basic properties, yields a deep red picrate, and on reductionfurnishes (X), a substance which it is hoped to synthesise andthus to establish the formula now assigned to physostigmine beyondreasonable doubt. It has since been shown that this formulaaccounts equally well for the formation of various other series ofphysostigmine derivatives. 83*Glyoxaline Derivatives.The condensation product of chloroacetic acid and 2-aminopyridine,which was regarded as “ pyridylglycine,” NC5H4*NH*CH,*C0,H,85is now shown to be 2-pyridoneimine-l-acetic acid,C0,H*CH2*N:C,H,:NH,since it is converted by heating into 1 -methyl-2-pyridoneimineYMeN:C,H4:NH.86 Similarly the supposed sodium salt of pyrindoxyl(I or 11) produced by the action of sodium hydroxide solution on“ pyridylglycine ” (Z-pyridoneimine- 1-acetic acid) has been pre-pared in various other ways, which leave no doubt that it is 2-keto-2 : 3-dihydropyriminazole (111), ring closure having occurred at theN-atom of the pyridine ring, not a t carbon atom 3, owing to tauto-merism of 2-aminopyridine.CHIn confirmation of this, it is found that 2-amino-3-mefhylpyridineywhen similarly treated, furnishes 2-keto-7-methyldihydropyrimin-azole. Oxidation of these dicyclic compounds to the correspondingdyes is effected with a single equivalent of potassium ferricyanide,836 M.andM. Polonovski, Bull. SOC. chirn., 1925, [iv], 37, 744; A., i, 959.84 K. Brunner, Monatsh., 1896, 17, 253; A., 1896, i, 625.85 F. Reindel, Ber., 1924,57, [B], 1381 ; A., 1924, i, 1235.86 A. E. Tschitschibabin, ibid., p. 2092; A., 1925, i, 158; see also thisReport, p. 139156 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.so that Reindel's conception of these products &s pyroindigotins(IV) is untenable and the constitution (V) is suggested for them.-A 'I (V.) R\-N-~oH I 1- H o G-N-\/N--C C--"\/Nitration of 2-phenylglyoxaline, like that of 4-phenylglyoxaline, 87produces predominantly the p-compound, the proportions of p-, o-,and m-compounds isolated being 60, 1.5, and 0.2% of the theoretical.The introduction of carboxyl groups progressively diminishes thisratio of para to meta nitration of the benzene nucleus ; thus 2-phenyl-4(or 5)-glyoxalinecarboxylic acid gives a mixture of p - and m-nitro-compounds, from which by decarboxylation the correspondingp - and m-nitrophenylglyoxalines are obtained in the ratio 52 : 19With 2-phenylglyoxaline-4 : 5-dicarboxylic acid this ratio is reversed,the proportion of p- to wz- being 19 : 52.The study of the methylation of 4(or 5)-R-glyoxalines has nowbeen carried a stage further by the use of diazomethane and of methylsulphate in presence of aqueous sodium hydroxide.** The productsformed are the 5 : 1 (I) and 4 :1 (11) -isomerides.(I.) RR'*e>CHCH-NGHoNMe>CH (11.1CR-NProportions of 5 : 1- and 4 : 1-isomerides formed.1.R =NO2 350 : 1 0.33 : 1 45 : 12. R = R r 45: 1 1:l 10: 13. R = P h 0.2: 1 (not feasible) 0-5 : 1(a) Me,SO,. (b) Me,SO,+NaOH. (c) CH,N,.The results indicate that in each case the more basic isomeridepredominates, except when methylation takes place in presence ofalkali. Thus in series 1 and 2 [the figures in series 2 refer to 2 : 4-(or 5)-dibromo-G(or 4)-methylglyoxaline] the stronger base isthe 5 : l-isomeride and this is formed almost exclusively in (a),predominantly in (c), and in equivalence or less with the 4 : 1-isomeride in ( b ) under alkaline conditions. These results correspondwith those obtained by Auwers in alkylating indazoles.8 7 F. L. Pyman and E. Stanley, J., 1924,125, 2484; compare Ann.Reports,1924, 21, 148.88 W. G. Forsyth and F. L. Pyman, J., 1925, 127, 573; compare Ann.Reports, 1924, 21, 148, and V. K. Bhagwat and F. L. Pyman, J., 1925, 127,1832ORGANIC CHEMISTRY. 157It has been suggested 89 that the isomerism exhibited by pilocarp-ine and isopilocarpine (IV) is not stereochemical but due to attach-ment of the side chain in positions 4 and 5, respectively. Themethiodides of the two alkaloids, which it is assumed on this viewshould be identica1,gO are different, but as one is an oil and the othercrystalline, making comparison difficult, they were converted intothe methochloroplatinates, which are both solid, melt a t about thesame temperature, but show depression of melting point on admix-ture. The difference between the two alkaloids must therefore,it is suggested, lie in the nature of the side chain : both yield ozonides,which on decomposition by water furnish different acids, pilocarpineyielding the methylamide of homopilopic acid (1),89 m.p. 104",[a]$, + 127.7", whilst isopilocarpine gives the methylamide ofhomoisopilopic acid, m. p. 53", [a]:;; + 93.9".?o*CHEt>CH*CH,*CO*NHMe ~o'CHEt>CH*CH2-C<cH.~ NH*CHO-CH, -CH,(1- 1 (11.)Another alkaloid of j aborandi leaves, pilocarpidine, has beenthe subject of two investigations during the ~ e a r , ~ l a the results ofwhich confirm a suggestion made in 188792 that it is the iminecorresponding to pilocarpine and is therefore represented byformula 11. It is converted by cold methyl iodide into pilocarpine,which, on further methylation and appropriate subsequent treat-ment, yields pilocarpine methochloroplatinate, identical with thatof Langenbeck.89 Pilocarpidine, on treatment with sodiumethoxide, is converted into isopilocarpidine, and the latter on methyl-ation furnishes isopilocarpine, which, it will be remembered, is alsoformed by the action of heat or alkalis on pilocarpine.The secondinvestigation 91b confirms the formation of pilocarpine ( I V ) frompilocarpidine by methylation, but shows that at the same time anisomeric base, neopilocarpine (111), is formed.(111.) (IV.)Like pilocarpine, the new isomeride is converted into a stereoiso-meric base, isoneopilocarpine, on treatment with alkali. Analyticalproof has already been given that in isopilocarpine and probably alsoin pilocarpine, since the evidence available indicates that these8a W.Langenbeck, Ber., 1924, 57, [B], 2072; A., 1925, i, 151.QO Compare F. L. Pyman, J., 1910, 97, 1814.Bb E. Spiith and E. Kunz, Ber., 1925, 58, [BJ, 513; A., i, 575.916 R. Burtles, F. L. Pyman, and J. Roylance, J., 1925, 127, 581.@a Harnaok, Anndm, 1887, 238, 228; compare A., 1886, 85158 ANNUAL REPORTS ON THE PROGRESS ow CHEMISTRY.bases are stereoisomerides, the homopilopic complex is attached inposition 5 and that the dimethylglyoxaline resulting from its degrad-ation is the 1 : 5- and not the 1 : 4-comp0und.~~ This view is nowconfirmed by the synthesis of 1 : 5-dimethylglyoxaline (VII), whichresults from the oxidation of 2-thiol- 1 : 5-dimethylglyoxaline (V),made by the condensation of a-methylaminopropionacetal (VI)with thiocyanic acid.GMe-NMe N>C*SH 4(EtO),CH*CHMe*NHMe + HCNS + CH(VI.1The 1 : 4-isomeride was also made, but the primary material inthis case was not so easily obtained and its preparation gave riseto interesting side reacti~ns.~lbPyraxole Deriratires.In the course of an investigation of the action of ketens onhydrazines,94 a series of-3 : 5-diketopyrazolidines was obtained by theuse of carbon suboxide. Thus phenylhydrazine combines with thesuboxide to form the unstable substance (I), which, on keeping,changes into the tautomeric phenyl-3 : 5-diketopyrazolidine (11) ;this yields a phenylhydrazine addition product (111) identical withMichaelis’s derivative of supposed 1 -phenyl-3 : 5-pyrazolidone.9~NPh--rH+ , Ph--rH,NHPh*NH,C O*CH,*C 0 TPh--W 4 ICO*CH,*C *OH C O*CH,*C 0With nuclear-substituted phenylhydrazines, analogous substancesare formed, but in these cases a molecule of phenylhydrazine attachesitself to the substituted diketopyrazolidine formed by means of thep-nitrogen, the products being assigned formulae of the type (111).Several long papers have appeared on isomeric relationships inthe pyrazole ~eries.~6 In the first of these, it was shown that noevidence could be obtained for the existence of isomeric alkylpyr-azoles of types represented by formulte (IV) and (V), analogous(1.1 (11.1 (111.)=liH (V.)RN<dHCH93 F.L. Pyman, J., 1922,121, 2616; compareH.A. D. Jowett, ibid., 1905,94 J. van Alphen, Rec. trav. chim., 1924, 43, 823; A., 1925, i, 80.06 Ber., 1892, 25, 1502; A., 1892, i, 1004.06 K. von Auwers and others, ibid., 1922, 55, [BJ, 3880; 1925, 58, [B],628; A., 1923, i, 151 ; 1925, i, 585; J. pr. Chem., 1925, [ii], 110,153,204,236;A,, i, 1176, 1178, 1180.87, 794ORGANIC CEEMISTRY. 159with those found in the indazoles,g' and that it was improbable thatthe 3- and &derivatives of pyrazole were identical, as had beenassumed by Knorr and others. The formation of I : 3-derivativesin cases where 1 : 5-derivatives would be expected? as in the oxid-ation of 1 : 5-dimethylpyrazolidineJ is assumed to be due to theinstability of the latter. The 1 : 5-dialkylpyrazoles appear to beincapable of existence , but 3- and 5-phenyl- l-alkylpyrazoles havenow been prepared.It has been suggested that the instability of the 1 : 5-dialkylderivatives is due to mutual repulsion of electrochemically similargroups , but the experimental results indicate that this explanationis inadequate.Rojahn's preparation of 3-chloro- 1 : 5-dimethyl-pyrazole, by the action of methyl iodide on the sodium salt of5-chloro-3-methylpyra~zole~~~ appeared to negative the view thatthe 1 : 5-dialkyl derivatives are unstable? and this reaction hasbeen fully investigated. 5 - C hloro- 3 -methylp yr azole , formed from3-methylpyrazol-&one by the action of phosphoryl chloride, mayhave either formula (VI) or (VII). On methylation, it can furnisheither 3-chloro-1 : 5-dimethylpyrazole (VIII) alone, or it mixture ofthis with 5-chloro-1 : 3-dimethylpyrazole (IX), depending on themethylating agent used and the conditions o b s e r ~ e d .~ ~-Me -= Me T M e -Me c ( ) m e +-- C&JNH or cliC JN + ~111 (IN \/NMe N NH \(VIII.) (VI.1 (VII.) (=-IBoth chlorodimethyl derivatives yield the same 5-chloro-1 : 2 : 3-trimethylpyrazolium iodide (type XI) with methyl iodide, and thisquaternary salt on heating yields the 1 : 5-dimethyl derivative(type VIII), the methyl group a t position 2 being eliminated asmethyl iodide.Similarly, when 5-chloro-3-methylpyrazole is treated with ethylbromide in alcoholic sodium ethoxide, the tri-substituted pyrazolesformed are C1: Me : Et = 5 : 3 : 1 and C1: Me : Et = 3 : 5 : 1.Ifthese in turn are treated again with methyl iodide, the products aremixtures of isomerides in which C1: Me : Me : Et = 5 : 2 : 3 : 1 and3 : 2 : 5 : 1. The same tetra-substituted products are formed bythe action of ethyl iodide on the two 5 or 3-chloro-2 : 3- or 2 : 5-dimethylpyrazoles , so that the formation of these quaternary saltsis formulated thus, the iodine atom being regarded as ionicallyattached to the whole molecule and not specifically to either nitrogenatom :\1/N87 Ann. Reports, 1924,21, 150.O 8 Ber., 1922, 55, [B], 2959; A., 1922, i, 1183.Compare this Report, p. 156160 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.When heated, these quaternary pyrazolium salts are decomposedinto pyrazoles and alkyl halides, the alkyl group being in prefer-ence lost from the nitrogen contiguous to the chlorine atom,l unlessthe other alkyl group possesses weak affinity, for example, benzyl orally1 : thus, 5-chloro-2-benzyl-1 : 3-dimethylpyrazolium iodide yieldsbenzyl iodide and 3-chloro- 1 : 5-dimethylpyrazole, whilst 5-cbloro-1 : 3- dimethyl-2- ethylpyrazolium iodide furnishes 3-chloro- &methyl-1 -ethylpyrazole.It is clear, therefore, that the presence of a chlorine atom greatlyincreases the stability of the 1 : 5-dialkyl derivatives, which areactually more stable than the 5-chloro-1 : 3-dialkylpyrazoles.The later papers deal with a similar investigation of the influenceon stability of the replacement of the 3(or 5)-methyl group byphenyl and with the N-alkyl and N-acyl derivatives of methyl-pyrazoles.In a study of the conditions under which phenylhydrazones ofunsaturated compounds pass into pyrazolines, it is pointed out thatwhilst unsaturated ketones generally give pyrazolines directly,unsaturated aldehydes furnish phenylhydrazones, which may beisomerised to pyrazolines.The presence of the p-nitro-group inphenylhydrazine tends to inhibit the formation of pyrazolines, whilstmethylhydrazine favours it. Colour reactions are inadequate meansof distinguishing between phenylhydrazones and pyrazolines, andreduction to the corresponding aniline, or hydrolysis by mixedacetic and sulphuric acids, is suggested instead for the simple, andsubstituted phenylhydrazones, respectively.2When pyrazolines are treated with potassium cyanate in aceticacid solution, the corresponding carbamides, e.g., 3 : 5 : 5-trimethyl-pyrazoline-1 -carbamide (I), are f ~ r m e d .~ These compounds are weakbases, yield well-crystallised picrates, and with acids regenerate theoriginal pyrazolines. The by-product obtained in the action ofsemicarbazide on mesityl oxide no doubt belongs to this type.It is interesting to note that the pyrazoline obtained as a degrad-Compare Ann. Reports, 1924, 21, 147, 148, refs. 91, 92, 93.a K. von Auwers and A. Kreuder, Ber., 1925, 58, [B], 1974; A., i, 1454;8 R. Locquin and R. Heilmann, Compt. rend., 1925,180, 1757 ; A., i, 837.4 M. Scholtz, Ber., 1896,29, 610; A., 1896, i, 343; compare C. Harries andF. Kaiser, ibid., 1899, 32, 1338; A., 1899, i, 637; H.Rupe and S. Kessler,W., 1909,42,4503,4715; A., 1910, i, 16.93.compare ibid., 1909, 42, 4411; A., 1910, i, 70ORGANIC CHEMISTRY. 161ation product of catechin has now been synthesised and shown tohave the constitution (11), although the product first formed isCMe,*CH,*CMe It N(1.1 I NH,*CO*NCH*CH,*CHC,H3( OMe),N- NHIf; :I (111.)probably represented by (III).5 This possibility has led to aninvestigation of the chances of such A-isomerism among these com-pounds. Although Buchner and Heide have recorded such casesfor methyl ethyl 4-phenylpyrazoline-3 : 5-dicarboxylates, they couldobtain from these only one 3-phenylpyrazoline (type 11) by methodswhich would be expected to yield A-isomerides, and in the presentinstance all attempts to prepare such isomerides failed so far as3-arylpyrazolines were concerned. On the other hand, two 3 : 5-anisylphenylpyrazolines (types I1 and 111) and their 4-hydroxy-derivatives have been obtained, and also two 3 : 5-phenylmethyl-pyrazolines and distinct 3- and 5-methylpyrazolinee, but attemptsto prepare pyrazolines containing the double linking between carbonatoms 3 and 4 or 4 and 5 failed.lndazole Deriratives.The synthesis of tetrahydroindazoles from cyclohexanone referredto last year has been extended to mono- and di-methylcyclo-hexanones and it has been found that a methyl group in the ortho-position to carbonyl favours the formation of 2-alkylindazoles ; inthe para-position it exerts no directive influence, whilst two methylgroups in the meta-position to carbonyl favours the production ofl-alkylindazoles. With phenyl in place of methyl groups, the differ-ences in orienting effect are less distinct.'Although it has been possible to prepare a number of indazoles bythe method of Reich and Gaigailian,s viz., the action of sodiumhydroxide on substituted hydrazones of 2 : 6-dinitrobenzaldehyde,all attempts to use it for the preparation of 1-acylindazolesfailed.gThe compound obtained by heating o-arninobenzhydrazide inpresence of quinoline a t 200" has been regarded as ( a ) 3-hydroxy-K.Freudenberg and others, Annalen, 1924,440, 36,38; A,, 1925, i, 69, 70.Ann. Reports, 1924,21,149.K. von Auwers, L. von Sass, and W. Wittekindt, Annulen, 1925, 444,Ber., 1913, 46, 2380; A., 1913, i, 996.K.von Auwers and E. Frese, Bw., 1925, 58, [Bj, 1369.195; A , , i, 1181; compareibid., 1923, 441, 68; A., i, 310.BEP.-VOL. XXII. 162 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.indazole 10 and (b) benzisopyrazolone.11 Further investigation showsthat it is bimolecular and is to be regarded as di-3-hydroxyindazole(I).12 3-Cyano-2-phenylindazole-l-oxide (11) has been prepared byC H *C OH)*T-$4HNH-N*(OH)C*C,H4 (I.) l 6 I (the action of aniline on o-nitromandelonitrile in alcohol in presenceof sodium acetate.13The alkylation of 3- and 5-methylindazoles has been investigated l4to see whether they behave like the simple pyrazoles15 and thetetrahydroindazoles.16 5-Methylindazole (111) behaves exactly likethe latter in giving 1- or 2- or both alkyl derivatives, depending onthe reagent used and the experimental conditions, and that is alsotrue of the 5-methylindazole-2-carboxylates.3-Met hylindazole(IV), on the contrary, shows some difference between the behaviourof free alkylpyrazole and alkylpyrazole forming part of an indazolecomplex. I n 3-methylindazoleY for example, the methyl groupappears to exert scarcely any directing influence in benzylation,mixtures of 1- and 2-benzyl-3-methylindazoles being formed, withthe latter usually predominating. The o- and p-nitrobenzoyl deriv-atives of 3-methylindazole (IV) exist in both stable and labile forms.The introduction of a bromine atom a t position 3 in 5-methylindazolescarcely affects the course of subsequent methylation.The 3 : 5-dibromo- 1 : 2-dimethylindazolium bromide on heating yields3 : 5-dibromo- 1 -methylindazole exclusively, whilst the correspond-ing 5 : 7-dibromo-compound furnishes a mixture of the I-methyl and2-methyl derivatives. The introduction of halogen in the benzenering of indazole reduces the basic character ; thus 5 : 7-dibromo-indazole no longer forms a picrate and is soluble in alkalis, whilst the3 : 5 : 7-tribromoindazole is definitely acid in character. In general,the 3-halogenated indazoles are more acid than basic.The question of the constitution of the labile and stable forms of10 G. Heller and W. Kohler, Ber., 1923, 56, [B], 1595; A., 1923, i, 850.11 C. Thode, J. pr. Chem., 1904, [ii], 60, 92; A., 1904, i, 347.12 A.Hantzsch, Ber., 1925, 58, [B], 680; A., i, 702.13 G. Heller and G. Spielmeyer, ibid., p. 834; A., i, 838.l4 K. von Auwers and A. Lohr, J. pr. Chem., 1924, [ii], 108, 297; A., 1925,15 Compare this Report, p. 159.i, 73.l6 Ann. Reports, 1924, 21, 160ORGANIU CHEMISTRY. 163acylindazoles is simplified16 by the admission that many of thecompounds previously described as " stable 2-acylindazoles " maybe acyl- 1 -indazoles, since the labile 2- toluenesulphonylindazolesreadily pass into the stable 1-derivatives. This reduces the numberof isomerides from three to two and renders the assumption ofstereoisomerism unnecessary : the spectrochemical behaviour ofthe two forms supports the view that they are structural isomerides.The formation of 2-acylindazoles, by the action of acyl chlorides onindazoles a t low temperatures, or on the silver salt, is now representedas taking place thus :whilst with the sodium salts the strongly electropositive metallicatom reacts directly with the chlorine of the acyl chloride, so that1 -acyl compounds are produced directly.17In the present Report several examples of the thermal decomposi-tion of the quaternary salts derived from pyrazole and indazolehave been given18 and this reaction has been used to determinethe relative tenacity with which radicals are attached to nitrogenin indazolium salts, 4/ \NR X, by measurement of therelative proportions in which 1 -alkyl- and 2-alkyl-indazoles areformed.19 When R' = Me and R is represented by various alkylgroups, the tenacity with which R is held increases from methyl topropyl or isopropyl and then diminishes : allyl, benzyl and sub-stituted benzyl groups are held less firmly than the methyl group,and the same order is generally maintained for the same groupsin position 1.These results only differ from those arrived a t byvon Braun 2o by other methods, as regards the position of the n-butylradical and the equivalence of the propyl and the Csopropyl group.[c \NR'/ CH 1Oxazoles and isoOxaxoles.The observation that chlorinated compounds are formed by theinteraction of epichlorohydrin and sodium cyanamide has necessi-tated a revision of views previously published as to the course ofthe reaction between ethylene chlorohydrin and sodium cyanamide.21The first change is the hydrolysis of disodium cyanamide,l7 K. von Auwers, Ber., 1925, 58, [BJ, 2081; A., i, 1460.lR This Report, pp. 160, 162.l9 K. von Auwers and W. Pfuhl, Ber., 1925, 58, [B], 1360; A,, i, 1100.*O J. von Braun and J Weismantel, ibid., 1922, 55, [B], 3165; A., 1922,a1 E. Fromm and others, AnnuZen, 1925, 442, 130; A., i, 594; compare A.,i, 1150.1922, i, 529.B 164 ANNUAL REPORTS ON THE PROGRESS OB CHEMISTRY.NC*NNa,, to the monosodium salt, NCONHNa, and sodium hydr-oxide, followed by the formation of ethylene oxide, which combineswith the monosodium salt to form an alcoholate, which is at oncehydrolysed to 2-amino-oxazoline (cyyamidoethyl alcohol) (I, inwhich *N:C*NH, may also act as *NH*C:NH) already known.22 Thelatter reacts with ammonium chloride to form 2 : 2-diamino-oxazoline(guanidoethyl alcohol ; 11). Epichlorohydrin with sodium cyan-amide gives 2-imino-5-chloromethyloxazolidine (111) ; .the latteris converted by ammonia into a substance, which is probably 2-amino-5-aminomethyliminazoline (IV). With chloroacetic acid sodiumcyanamide yields as the main product dicyanodiamidoacetic acid(cyanoguanidoacetic acid), which can react in either of the two formsshown (V).CH2C1* $!H-o> C:NHCH,*N FH2'0>C*NH, CH,*NH T"2-O >C(NH,), CH,*NHA series of compounds of type 1 has been prepared by the dehydr-ation of amino-acids, usually with phosphorus pentachloride.23Closure of the ring becomes more difficult as the weight of the acylresidue increases; thus in the case of the acylglycine esters,R*CO*NH*CH,CO,Et or R*CO*NH*CHR'*CO,Et, the ethyl ester ofkovalerylglycine yields 5-ethoxy-2-isobutyloxazole (I ; R = C,H,),but that of n-hexoylglycine gives only a trace of oxazole, whilstthose of n-octoylglycine and its higher homologues remain un-attacked. The ethyl ester of d-cr-methyl-n-butyryl-Z-leucine yieldsthe optically active 5-ethoxy-4-isopropyl-2-sec.-butyloxazole, butthis on hydrolysis furnishes an inactive leucine. The hope that anactive amino-acid might be obtained in the hydrolysis in presenceof a second asymmetric carbon atom in the substituent acyl groupwas not realised.(I.) Eto'f?o>C*RR *CONThus hydrolysis of 5-ethoxy-2-1' : 2' : 2' : 4'-tetramethylcycZo-pentyl-4-isobutyloxazole (11), in which the groups C,H, and C9Hl,are both optically active, furnished only inactive leucine andd-campholyl-dl-leucine.22 S . Gabriel, Ber., 1889, 22, 1139; A., 1889, i, 848.z3 P. Karrer and others, Helv. Clhim. Acta, 1924, 7, 763; 1925,8, 203, 205;C. Granacher, $bid., 1925, 8, 211; A., 1924, i, 1118; 1925, i, 594ORGANIC CHEMISTRY. 165A comparison 24 of the optical properties of indoxazen with thoseof a number of isooxazoles confirms the structure (I) assigned to theformer.25An interesting series of isooxazoles has been prepared by theaction of hydroxylamine on substituted thioamides of ethyl acetyl-malonate.26 A typical example is 3-anilino-5-ketoisooxazole (11),formed by treating the additive compound of ethyl acetylmalonateand phenylthiocarbimide with hydroxylamine. With hydrazine,a similar series of pyrazoles is formed.The small yields obtained in reactions used for the preparationof cyclopropane derivatives, having a nitro-group attached to oneof the carbon atoms of the ring (I), is due to secondary reactionsin which hydrogen bromide is eliminated from the aci-form (11)of the nitro-compound, resulting in the formation of isooxazolinewhich are represented by formula 111, or its tautomericR*CH-CHCOR R*CH*CHBr*COR + I +\C/RNO, CH,*NO,R*CH*CHBr COR R-CHGHCOR(1.1(11.1 1 -+ I >o (111.1CH-NO, CH:N:Oform in which the oxygen is held between the nitrogen atom andcarbon atom 3 thus, C-N, (111) being preferred. These oxidescombine with water, aldohols, ammonia, and amines, forming com-pounds which are all similar in type and are represented, in the caseof the water additive product, by formula (IV) or (V), of which (V)is preferred on account of its similarity to that of a known hydroxy-isooxazolidone (VI), which, like these addition compounds, formsa copper derivative.281 1 I‘O/R*CHCH*COR’ R*CH-CHeCOR’ CH,*COH=N(OH), CH( OH)*N*OH R*CH--N*OH(IV.1 (V-1 (VI. 1In later work, phenylated derivatives of these isooxazoline oxides24 K. von Auwers, Ber., 1924, 57, [B], 461; A., 1924, i, 572.z5 A. Conduch6, Ann. Chim. Phya., 1908, [iii], 13, 5; A,, 1908, i, 154.26 D. E. Worrall, J . Amer. Chem. SOC., 1922, 44, 1651; 1923, 45, 3092;1924, 46, 2832; A., 1922, i, 874; 1924, i, 208; 1925, i, 308.27 E. P. Kohler, ibid., 1924, 46, 503, 1733, 2105; A., 1924, i, 571, 998, 1239.z 8 T. Posner, Ber., 1906, 39, 3515; A., 1907, i, 55.j ; 9-0 I >o I >166 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.were prepared, which are represented by the same type of formula,although they differ considerably in properties from the originalcompounds; thus they are not ruptured by strong bases, form noadditive compounds with water, etc., do not yield insoluble copperderivatives, and are dehydrated instead of being acylated by acidchlorides and anhydrides. These differences are ascribed to theabsence of the labile hydrogen atom in position 3 as in Ei-benzoyl-3 : 4-diphenylisooxazoline oxide (compare I V for numbers). 3 : 4 : 5-Triphenylisooxazoline oxide is obtained by the condensation ofnitrostilbene with phenylnitromethane in presence of sodiummethoxide, probably according to the following scheme :CHPh:CPh*NO, CHPh*CHPh*NO, CHPheCHPh3- - I - 1 >oCPh===N:O CH,Ph*NO, CHPh*NO,This product contains no reactive group except the system06 = fi:O characteristic of these compounds. It is readily convertedinto triphenylisooxazole 29 by boiling with aqueous-alcoholic sodiumhydroxide, and this " stripping " by the alkali is no doubt the sourceof the same isooxazole, which is the chief by-product of the reactionin which the oxide is formed. This oxide again differs markedly inits reactions from those previously described. Reduction with zincand acetic acid converts it into 2-hydroxy-3 : 4 : 5-triphenyliso-oxazoline, which is also obtained by the action of magnesium ethylbromide on the oxide. With phosphorus pentachloride the oxidebehaves like diphenylfuroxan 30 (diphenylisooxadiazole), oxygenbeing lost and triphenylisooxazoline formed.The condensation of 2-hydroxymethylenecyclohexanone withhydroxylamine hydrochloride gives a mixture of the two isomerictetrahydrobenzisooxazoles 31 of types I and I1 (R = H), the 4 : 5-compound (type I) predominating always and in presence ofQH2-CH2-y=?H(11.1CH,-CH,-G-GH(I*) hH2*CHR*C*O*N CH,*CHR*C:N*Ohydrochloric acid forming 85% of the product. 6-Methyl-2-hydroxymethylenecyclohexanone behaves similarly, and in thiscase attempts to increase the yield of the 3 : 4-product (type 11) bythe use of 2-ethoxymethylenecycZohexanone gave a mixture of pro-ducts (I11 and IV). I n neutral solution the free hydroxymethyIene29 Compare J. Meisenheimer and K. Weibezahn, Ber., 1921, 54, [B], 3195;A., 1922, i, 176.90 H. Wieland and 1,. Semper, Annalen, 1007, 358, 36; A., 1908, i, 108.31 K. von Aumers, T. Bahr, and E. Frese, Anmlen, 1925, 441, 54; A,, i,308ORGANIC CHEMISTRY. 167H,-CH,-$?H*CH:NOH $!H,-CH,-fl*CH:NOH $!H,-CH,-R*CNH,*CHMe*CO CH,*CHMe*C*OH CH,*CHR*C*ONa(111.) W.) (V.1 xketone also yields (IV), which readily loses water and forms the4 : 5-isooxazole (I). The course of the reaction therefore appearsto be-$XCH*OR’ _3 -$JH*CH(OR’)*NH*OH +-GO -co-?H*f?NH*oH -+ (111 and IV) -+- (I.)-COAll four substances are volatile liquids and the tetrahydrobenz-isooxazoles (I and 11) closely resemble the corresponding dialkyl-isooxazoles. The 4 : 5-compounds (I) are decomposed in the coldby sodium methoxide, giving the enolic forms of the cyanoketones(V), which yield oximes readily convertible by traces of alkali intoC-aminotetrahydrobenzisooxazoles, except in the case of 2-cyano-2-alk ylcyclohexanones .32T. A. HENRY.82 K. von Auwers, T. Bahr, and E. Frese, Annulen,, 1925, 441, 68; A.,i, 310

ISSN:0365-6217    

DOI:10.1039/AR9252200067

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

ANALYTICAL CHEMISTRY.THERE is no record during the year of any advance in analyticalmethods of an entirely novel character. As is usually the case,the publications generally deal with improvements in well-knownprocesses and applications to special problems. Certain attemptsto apply the methods of X-ray analysis beyond the rare earths havebeen recorded, and it seems not unlikely that progress in thisdirection may furnish another method of general utility. Thelimitations of various indicators have been the subject of furtherinquiry and several applications of electrometric titration havelikewise been communicated, further demonstrating the eleganceof this method when properly applied. New apparatus and micro-chemical methods of analysis are not dealt with in this Report,because they are not sufficiently numerous or important to callfor special attention on this occasion.Inorganic Analysis.Qualitative.-A series of reactions, carried out on a drop of solu-tion, has been devised for the qualitative analysis of solutionscontaining the nitrates of most of the metals of the first threegroups ; in another scheme, a preliminary separation into groupsis carried out by treating the precipitated sulphides of all themetals with acids of different concentration.l In this connexion,the interesting study on the behaviour of precipit,ated sulphides ofthe heavy met& is of importance.When nickel sulphide is pre-cipitated together with lead sulphide, it is appreciably soluble in1 : 10 hydrochloric acid, wherea,s its solubility in acid when pre-cipitated alone is small.Digestion with acetic acid of a mixtureof coprecipitated zinc and manganese sulphides fails to dissolveall the manganese. From among other examples given in thestudy may be cited the fact that the ordinary hydrogen sulphidemethod fails to effect a complete separation of mercury from zincand cadmium and of tin from cobalt.2Characteristic precipitates are given by copper in neutral solutionwith thiocyanate and tolidine and with iodide and benzidine;1 N. A. Tananaev, 2. anorg. Chem., 1924, 140, 320; A., 1925, ii, 324.2 F. Feigl, 2. anal. Chem., 1924, 65, 25; A . , 1925, ii, 70.3 G. Spam, i b i d . , 1925, 67, 31; A , , ii, 1003ANALYTICAL CHEMISTRY. 169the formation of a deep violet coloration due to copper bromidemay be used as a sensitive reaction for either of these ions.4 Tracesof gold may be detected by the alteration in colour of a silver solproduced from silver nitrate, metol, and sodium sulphite.Basic bismuth nitrate has been applied to the removal of phos-phates and of oxalates; 6 zirconium oxychloride has also beenused in the case of phosphates.' The method sometimes adoptedof eliminating phosphoric acid by heating the precipitated phos-phates with sodium carbonate is completely successful only in thecase of iron and barium.sAluminium salts in neutral solution yield a characteristic greenfluorescence with solutions of morin or of morinsulphonic acid,and it is claimed that the test is of great deli~acy.~ In the absenceof ferric iron, the formation of a crimson lake with aurintricarb-oxylic acid, insoluble in ammonia containing ammonium carbonate(by which interfering " lakes " from chromium and the alkalineearths are removed), indicates the presence of aluminium.1°A delicate test for cobalt depends on the formation of a blueprecipitate with sodium silicate, soluble in excess of the reagent,the pale green precipitate given by nickel under the same conditionsbeing insoluble.llThe characteristic precipitates or colorations given by solutionsof copper, iron, and cobalt salts with dinitrosoresorcinol have beenemployed as sensitive tests for these metals.12Sodium oxalate is less soluble in a saturated solution of am-monium oxalate than in water, and this fact has been utilised forthe detection of sodium.13 Alternatively, enough alcohol must beadded to the aqueous solution to produce a concentration of 30%alcohol by v01ume.l~ A filter dyed with crystal-violet is statedto be superior to blue glass in the flame test for potassium.15The intense red colour produced when sodium chloro-osmate isK.Scheringa, Phurm. Weekblad, 1925, 62, 173; A., ii, 326.5 A. Steigmann, Chem. Ztg., 1925, 49, 423; A., ii, 719.6 A. Keschan, 2. anal. Chem., 1925, 65, 346; 67, 81; A , , ii, 328, 1008.7 L. J. Curtman, C. Margulies, and W. Plechnor, Chem. News, 1924, 129,* A. Colani, Bull. SOC. chim., 1925, [iv], 37, 937; A., ii, 1001.a E. Schantl, Mikrochem., 1924, 2, 174; A . , 1925, ii, 440.10 L.P. Hammett and C. T. Sottery, J. Amer. Chem. SOC., 1925, 47, 142;l1 S. J. Tindal, Chem. News, 1925,130, 34; A., ii, 242.12 M. L. Nichols and S. R. Cooper, J . Amer. Chem. Xoc., 1925, 47, 1268;la J. Meyerfeld, 2. and. Chem., 1925, 6'4, 160; A., ii, 1202.l4 L. W. Winkler, Pha?m. .Zen.fr., 1925, 66, 669; A . , ii, 1095.200, 315; A., 1925, ii, 68.A., ii, 601.A., ii, 715.J. Meyer, Helv. China. Acta, 1925 8, 140; A . , ii, 601.F170 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.boiled with thiocarbamide in the presence of a little hydrochloricacid may be used as a test for osmium, the test being sensitive to1 part in 100,000.16Colour reactions of nitrates and nitrites with various organiccompounds are described.17 The nitrate and perchlorate of a-phenyl-P-diethylaminoethyl p-nitrobenzoate, whilst too soluble to be ofvalue for gravimetric determination of the anions, are availablefor their qualitative detection.l8 A study has been made of thedelicacy of the ferrous sulphate test for nitrate and nitrite and thediphenylamine reaction; l9 and a test for nitrate is described basedon reduction to nitrite by metallic lead, any nitrite originally presentbeing removed by appropriate mezLns.20Ammonia may be detected in the presence of and removedfrom a solution of an aliphatic amine salt by precipitation withsodium cobaltinitrite and sodium nitrite.21Quantitative.-Borax has been found to be suitable as a stan-dardising reagent, both for acids and for bases, the indicators ofappropriate pH range being methyl-orange and phenolphthalein,respectively.22 Aminosulphonic acid 23 and p-nitrobenzoic acidare other suggested standards.The mixture in equal proportions of neutral-red and phenol-redgives a sharp colour change at the point of real neutrality at px 7 ~ 0 7 .~ ~A detailed investigation of the influence of alcohol, salts, andtemperature on the change point of dimethyl-yellow, bromophenol-blue, and phenolphthalein has been made.26 Potassium ferritri-pyrocatechol-oxide is an indicator similar in many respects toPhenolphthalein in its behaviour. The colour change is due to analteration in the complex anion.27Chloramine T behaves like an inorganic hypochlorite, but ismuch more stable, so that with the addition of a small amount ofl8 L.Tschughaev, 2. anorg. Chem., 1926,148, 65; A., i, 1395.l7 S. VQgi, 2. anal. Clzem., 1925, 66, 14, 101; A., ii, 599; A. Novelli, Anal.Asoc. Quim. Argentina, 1925, 13, 13; A., ii, 900; L. Ekkert, Phamn. Zenbr.,1925, 66, 733; A., ii, 1200.1* C. S. Marvel and V. du Vigneaud, J. Amer. Chem. Soc., 1924, 46, 2661;A., 1925, ii, 240.19 F. L. Hahn and G. Jaeger, Ber., 1925, 58, [B], 2340; A., ii, 1199.20 Ibid., p. 2335; A , , ii, 1199.21 P. Leone, Qazzettn, 1925, 55, 246; A., ii, 907.22 M. G. illellon and V. M. Morris, Ind. Eng. Chem., 1925, 17, 145; A.,23 L. Herboth, Arch. Pliarm., 1924, 262, 517; A., 1925, ii, 155.24 W. M. Thornton, jun., and D. Getz, Anzer. J. Sci., 1925, [v], 9, 176;25 G. Chabot, Bull. SOC. chim. BeEg., 1925, 34, 202; *A., ii, 899.2 6 A.Richter, 2. anaE. Chem., 1924, 05, 209; A,, 1925, ii, 237.37 K. Binder, {bid., 1925, 66, 1; A., ii, 596.ii, 325.A., ii, 597ANALYTICAL CHEMISTRY. 171potassium iodide and starch as indicator, it can replace iodine inmost analytical processes.28When standardising thiosulphate solutions, considerable economyin potassium iodide may be secured by using a slight excess ofpotassium iodate over the amount required to produce sufficientiodine, a small crystal of the iodide, and titrating very slowly.This method would appear to be advantageous when large quantitiesof thiosulphate solutions are used.29 Hydrazine sulphate is pro-posed as a more satisfactory standard for iodometry than thio-~ u l p h a t e , ~ ~ whilst the conditions necessary for the accurate stan-ciardisation of thiosulphate solutions against iodine or potassiumpermanganate, dichromate or bromate are discussed in detail.31Attention is again directed to the greater delicacy obtainable bythe use of liquids such as benzene and carbon tetrachloride in theplace of starch.32 Methods depending upon the formation ofcyanogen iodide are applied to the determination of numeroustypes of substances, such as hydrazine, hydrogen peroxide, andcyanides .33Bromine solutions in N-potassium bromide are the most suitablefor general use for volumetric work. Applications of this reagentand of hypobromite to the determination of iron, tin, and othersubstances are described.34Reduction with liquid lead amalgam followed by titration withpermanganate has been applied to ferric and uranyl salts, totungstic, titanic, and molybdic acids, and to the determination ofphosphorus by reduction of the molybdenum in ammonium phospho-molybdate .35A rapid method of determining metals in mercury is based on the factthat all metals more electropositive than mercury, except cobalt, passrapidly into solution as sulphates when their amalgams are shakenwith permanganate in dilute sulphuric acid; the end-point is indi-cated by the breaking of the surface of the mercury into bubbles.3628 A.Noll, Chem. Ztg., 1924, 48, 845; A., 1925, ii, 66.29 M. Dimitrov, 2. anorg. Chern., 1924, 136, 189; A., 1925, ii, 598.30 E. Cattelain, J . Pharm. Chim., 1925, [viii], 2, 387; A., ii, 1197.31 S.Popov and J. L. Whitman, J . Amer. Chem. SOC., 1925, 47, 2259;32 N. Kana, S c i . Rep. Tdhoku Imp. Univ., 1925, 14, 101; A., ii, 1010;33 R. Lang, 2. anorg. Chem., 1925,142,229, 280; 144, 75; A., ii, 713.34 W. Manchot and F. Oberhauser, ibid., 1924, 139, 40; A., 1925, ii, 161 ;F. Oberhauser, ibid., 1925, 144, 257; A., ii, 828; R. Lang, 2. anal. Chem.,1925, 67, 1 ; A., ii, 1009.K. Someya, 2;. anorg. Chem., 1925,145, 168; 148, 68; A., ii, 904, 1201.A., ii, 1093.I. M. Kolthoff, Pharsn. Weekblad, 1925, 62, 878; A., ii, 1000.36 A. S. Russell and D. C. Evans, J., 1925, 127, 2221.F" 172 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The reaction between sodium hydroxide and solutions of a numberof metals has been followed electrometrically by the hydrogen andoxygen electrodes, and the possibility of graded precipitation ofhydroxides is discussed in detai1.37The pyridine-thiocyanate precipitation of copper has beenapplied to the separation of this element from mer~ury.~8 Ethylacetonedioxalafe may be utilised for the separation of copper,especially in small quantities, from cadmium and zinc39 For thequantitative conversion of cupric sulphide into cuprous sulphide,it is claimed that heating in an atmosphere of hydrogen and hydrogensulphide followed by cooling in an atmosphere of carbon dioxidecontaining methyl alcohol vapour gives accurate results, whereasthe method of heating in hydrogen alone is stated to lead toerroneous results ,40An iodometric determination of lead depending upon the pre-cipitation of lead as sulphite has been worked Knop'stitration of dichromate and iron in the presence of diphenylamineas indicator is applied to the determination of lead obtained aschromate.42 Some caution is necessary with dilute solutions orlead nitrate used as standards.These appear to undergo hydrolysison keeping, the lead content segregating towards the bottom oftop layers according as the water used is boiled or not, and inter-action of the lead salt with the glass is also involved.43Bismuth may be separated from lead by means of pyrogallol,with which bismuth forms a precipitate q~antitatively.~~ Freshlyprepared bismuth sulphide is completely soluble at 30" in hydro-chloric acid-1 of concentrated acid to 3 of water-whilst pre-cipitation as sulphide is complete in 1 : 5 a ~ i d .~ 5 The deep redcolour given by bismuth iodide with bases, e.g., tetra-acetylam-monium hydroxide, may be utilised for the determination of smallamounts of bismuth in tissue, e t ~ . ~ ~For the separation of cadmium from zinc by means of hydrogensulphide in acid solution, definite minimum acidity is necessary.Ammonium sulphate assists the precipitation ; 47 the cadmium may37 H. T. S. Britton, J., 1925,127, 2110-2159.38 G. Spacu, 2. anal. Ghem., 1925, 67, 27; A., ii, 1004.8g A. Jilek and J. Lukas, Chem. Listy, 1925, 19, 275; A., ii, 903.40 F. L. Hahn, 2. anal. Ghem., 1924,65, 134; A., 1925, ii, 160.41 C. E. Richards, Analyst, 1925, 50, 398; A., ii, 903.42 W. W. Scott, Ind.Eng. Chem., 1925, 17, 678; A., ii, 903.43 H. Bernhardt, 2. anal. Chem., 1925, 6'9, 97; d., ii, 1003.44 F. Feigl and H. Ordelt, ibid., 1925, 65, 448; A., ii, 442.45 S. Ramachandran, Chem. News, 1925, 131, 135 ; A., ii, 1005.46 A. Girard and E. Fourneau, Compt. Tend., 1925,181, 610; A., ii, 120'7.4 7 G. Luff, 2. anal. Chem., 1924, 65, 97; A., 1925, ii, 159ANALYTICAL CHEMISTRY. 173subsequently be precipitated and weighed as cadmium diammoniumferr~cyanide.~~Improvements in the separation of arsenic from antimony andtin by distillation of the chlorides have been effected, and it isfound that the volatilisation of the arsenic chloride is complete ifa current of carbon dioxide is passed through the apparatus main-tained a t water-bath temperature for 2 hours.49 A more rapidquantitative separation of the arsenic is stated to be obtainedif the special flask described provided with a fractionating inset isemployed.50Iron may be precipitated as hydroxide from hot dilute solutionscontaining an excess of ammonium thiocyanate by means ofpyridine, thereby allowing a separation from mercury.51 The highresults obtained by ignition of ferric hydroxide precipitated byammonia may be rectified by a second ignition following on treat-ment with a little nitric acid.52 Conditions have been worked out,especially with reference to ores, for the complete separation ofnickel and copper from iron by means of ammonia and ammoniumsalts.53For the colorimetric determination of iron, the ferrocyanidemethod is preferred to the thiocyanate method, with which phos-phates interfere.54 The difficulty in determining iron by salicylicacid or as thiocyanate when tartaric and citric acids are present issurmounted by taking advantage of the blue colour produced byalloxantin with ferric iron in alkaline solutions.55Aluminium, like iron and manganese, is precipitated on boilingsolutions of its salts with hexamethylenetetramine, which possessesthe advantage over ammonia that it does not absorb carbon dioxideand so avoids contamination of the precipitate with calcium.56Aluminium hydroxide, again like iron, precipitated by means of" infusible white precipitate '' (ClHg*NH,) filters more readily thanthe form produced by ammonia and is separated completely frommanganese in one operation.57 Either sodium alizarinsulphonateor the colouring matter of pzeonies may be used as indicator with48 G. Luff, Chem. Ztg., 1925, 49, 513; A., ii, 826.4Q K. Rohre, 2. anal. Chern., 1924, 65, 109; A., 1925, ii, 157.61 G. Spacu, 2. anal. Chem., 1925, 67, 147; A., ii, 1206.62 N. A. Tananaev, 2. anorg. Chem., 1924, 136, 184; A., 1925, ii, 603.53 E. G. R. Ardagh and G. M. Broughall, Univ. Toronto, Sch. Eng. Res.64 W. B. Walker, Analyst, 1925, 50, 279; A,, ii, 717.55 G. Denigk, Compt. rend., 1925, 180, 519; A., i, 441.5 6 C. Kollo and N. Georgian, Bul. SOC. Chim. Romdnia, 1924, 6, 111 ; A.,5 7 B. Solaja, Chem. Ztg., 1925, 49, 337; A., ii, 602.F. L. Hahn and H. Wolf, Ber., 1924, 57, [B], 1858; A,, 1925, ii, 68.Bull., 1925, 5, 227; A., ii, 603.1925, ii, 330174 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.potassium hydroxide for determining excess of sulphuric acid in asolution of aluminium s~lphate.~* In another method, the alumin-ium salt-is converted into a complex oxalato-compound by treat-ment with excess of alkali oxalate, and the “residual” aciditydetermined iodometricalIy.5gBoiling with sodium nitrite has been applied as a means ofseparating iron, chromium, aluminium, and phosphoric acid fromzinc, nickel, cobalt, and manganese.60 Sulphosalicylic acid alsohas been used for various separations in this group.61For the determination of zinc in solutions containing alkali ormagnesium salts, precipitation with thiocyanate and pyridinefollowed by ignition to oxide gives satisfactory results ; 62 cyanamidealso can be used for this purpose.63Two volumetric methods of determining manganese have beendescribed, one using permonophosphoric acid,64 the other dependingon the precipitation of manganous chromate 65 (MnCr04,2H,0) bymeans of potassium chromate and titration of the excess ofchromate.In the dimethylglyoxime determination of nickel in the presenceof iron and cobalt, high results are obtained due to the precipitationof an iron-cobalt-glyoxime unless the iron be in the ferrouscondition.G6 a-Furildioxime 67 and oxalenediuramidoxime 68 alsoare reagents for nickel.Details are given for a, colorimetricdetermination of cobalt in presence of nickel, utilising the colourproduced by ammonia and sodium peroxide.69It is found that citric acid does not prevent the complete pre-cipitation of calcium provided sufficient excess of ammoniumoxalate is used,’* and it has the advantage of causing the calciumoxalate to separate in a form not isomorphous with magnesium6 8 T.Sebalitschka and G. Reichel, Arch. Pharm., 1925, 263, 193; A., ii,602.60 F. Feigl and G. Krauss, Ber., 1925, 58, [BJ, 398; A., ii, 329.60 K. K. Jlirvinen, 2. anal. Chem., 1925, 66, 81; A., ii, 602.61 L. Moser and A. Brukl, Ber., 1925, 58, [B], 380; A., ii, 329.62 L. A. Congdon, A. B. GUSS, and F. A. Winter, Chem. Neuw, 1928, 131,63 W. Marckwald and H. Gebhardt, 2. anorg. Chem., 1925, 147, 42; A.,6* T. Heczko, ibid., 1925, 143, 129; A., ii, 440.66 B. N.Angelescu, Bul. Xoc. Chim. Romdnia, 1924, 6, 109; A., 1925, ii,6 6 J. G. Weeldenburg, Rev. trav. chim., 1924, 43, 465; A , , 1925, ii, 72.6 7 B. A. Soule, J . Amer. Chem. SOC., 1925, 4’9, 981 ; A., ii, 603.68 F. Feigl and A. Christiani-Kronwald, 2. anal. Chern., 1925, 65, 341;69 B. S. Evans, Analyst, 1925, 50, 389; A., ii, 904.70 W. F. Jakbb, Roczniki Chemii, 1923, 3, 308; A., 1926, ii, 69.65, 81, 97, 113; A., ii, 1002.ii, 1002.330.A., ii, 330ANALYTICAL CHEMISTRY. 1760xalate.~1 The question of the accuracy of the oxalate separationof calcium and magnesium has been examined again during the yearby several observers and suggestions for the best conditions ofseparation are given. 72Sodium salts are preferable to ammonium salts as precipitantsfor magnesium ammonium phosphate or arsenate.73 The accuratedetermination of magnesium in aluminium alloys is nowadays ofconsiderable importance.Small amounts of magnesium in thepresence of large quantities of aluminium are conveniently separat.edfrom most of the latter by precipitation with excess of alkalihydr0xide,7~ since the direct deposition of magnesium ammoniumphosphate in the presence of tartaric acid requires several days.75Mixed solvents consisting of alcohols and ethyl acetate areadvocated for the separation of the alkali perchlorates.76 Thedetermination of alkalis by Berzelius's process in silicate analysismay be hastened by heating to dull redness the product of thehydrofluoric-sulphuric acid treatment ; extraction of the coldmass with water leaves a residue free from alkalis.77 A practicablescheme for determining silica and lithium in lithium minerals isdes~ribed.'~Small proportions of iron and aluminium may be removed fromgallium by precipitation with excess of ammonium hydroxide,?gwhilst gallium may be separated from many metals with which itoccurs by extraction of its solution in 5-6N-hydrochloric acidwith ether.s0For the oxidation of precipitated germanium disulphide, hydrogenperoxide acting on an ammoniacal solution of the sulphide ispreferred to the more customary nitric acid.81Iron may be separated from tantalum and columbium as sulphideby adding oxalic and tartaric acids and then rendering alkaline71 W.F. Jakbb, Roczniki Chemji, 1925, 5, 159; A,, ii, 1095.la Bach, Chem.Ztg., 1925, 49, 514; A., ii, 825; R. Heilingotter, ibid.,241; A., ii, 437; V. Rodt and E. Kindscher, ibid., 1924, 48, 953, 964; A.,1925, ii, 158; G. Luff, 2. anal, Chem., 1925, 65, 439; A., ii, 438.73 L. A. Congdon and G. Vanderhook, Chem. News, 1925, 130, 241, 258,273 ; A., ii, 601.74 F. L. Hahn and S. Scheiderer, Ber., 1924, 57, [B], 1854; A., 1925, ii, 69.7 5 G. Jander, E. Wendehorst, and B. Weber, 2. anorg. Chem., 1925, 142,'6 G. F. Smith and J. F. Ross, J . Arner. Chem. Soc., 1925, 47, 762, 774,7 7 0. Cantoni, 2. anal. Chem., 1925, 67, 33; A., ii, 1001.7 8 A. Guntz and F. Benoit, Bull. SOC. chirn., 1925, riv], 37, 1294; A., ii,79 R. Fricke, 2. anorg. Chem., 1925, 144, 267; A., ii, 717.80 3%. H. Swift, J .Amer. Chem. SOC., 1924, 46, 2375; A,, 1925, ii, 71.81 E. B. Johnson and L. M. Dennis, ibid., 1925, 41, 790; A., ii, 442.329; A., ii, 715.1020; A., ii, 436, 437, 601.1202176 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.with ammonia. The rare metals are separated from the treatedfiltrate from the iron sulphide by means of “ cupferron.” 82 Thetwo metals can be separated from each other s3 by a process depend-ing on the differential hydrolytic dissociation between oxalotantalicand oxalocolumbic acids in the presence of tannin.Sexavalent uranium salts are preferably reduced to the quadri-vnlent form by means of lead and hydrochloric acid prior totitration, since the usual metallic reducing agents always produceslight over-reduction.84 Rare earths may be satisfactorily separatedfrom uranium by the oxalate method by conversion of the uraniuminto uranylsalicylic acid .s5The vanadium in a vanadate solution, obtained by oxidationwith alkaline hydrogen peroxide solution, may be determinediodometrically,86 whilst vanadium may be determined in thepresence of iron, e.g., in a vanadium steel, by titration with ferrousiron with diphenylamine as indicator.87From nitrite solution, small amounts of palladium can be cleanlyprecipitated by means of dimethylglyoxime in the presence oflarge quantities of platinum; 88 when, however, the proportion ofpalladium is high, precipitation with or-nitroso- p-naphthol, acetylene,dimethylglyoxime, or mercuric cyanide yields a bulky precipitatewhich retains some platinum.I n such a case, prior removal of thelatter metal as ammonium chloroplatinrtte is rec~mmended.~~Platinum may be quantitatively separated from ruthenium bytreatment with sodium hydroxide, glycerol, and bromine.g0Conditions have been worked out for the separation of zirconiumand hafnium from titanium, cerium, and thorium by means ofsodium a r ~ e n a t e . ~ ~Molybdenum trisulphide may be obtained in a form whichfilters readily by acidification of the molybdate solution treatedwith fresh ammonium polysulphide. It affords an oxide, on gentleroasting, which may contain traces of ferric oxide, silica, zinc oxide,copper oxide and vanadium pentoxide; these should be deter-mined and correction made for them.e2 I n the conversion of82 H.Pied, Compt. rend., 1924, 179, 897; A., 1925, ii, 442.83 A. R. Powell and W. R. Schoeller, Analyst, 1925, 50, 485; A., ii, 1096.84 0. Koblic, Chem. LGty, 1925, 19, 1 ; A., ii, 331.G. Canneri and L. Fernandes, Gazzetta, 1924, 54, 770; A., 1925, ii, 71.86 A. E. Stoppel, C. F. Sidener, and P. H. M-P. Brinton, J . Amer. Chem.87 K. Someya, 2. anorg. Chem., 1924, 139, 237; A., 1925, ii, 161; N. H.SOC., 1924, 46, 2448; A., 1925, ii, 73.Furman, Ind. Eng. Chem., 1925,17, 324; A., ii, 442.H. E. Zschiegner, Ind. Eng. Chem., 1925, 17, 294; A,, ii, 443.F. Krauss and H. Deneke, 2. anal. Chem., 1925, 67, 86; A., ii, 1005.go 0. Ruff and E. Vidic, Z. anoTg. Chem., 1925, 143, 163; A., ii, 443.B1 L. Rloser and R. Lessing, Monatsh., 1924, 45, 323; A., 1925, ii, 718.s2 W.Hartmann, 2. anal. Chzm., 1925, 67, 152; A., ii. 1206ANALYTICAL CHEMISTRY. 177molybdenum sulphide into oxide by ignition, a temperature of600" should not be exceeded.93 Two colorimetric methods of deter-mining molybdenum in the form of sulphide 94 or thiomolybdate 95in acid and ammoniacal solutions, respectively, are described.In the determination of boric acid through the methyl ester,aluminium, chromium, and iron must first be removed. A pro-cedure for securing the removal of these metals without loss ofboric acid is de~cribed.~6 This acid may be titrated with sodiumhydroxide in the presence of saturated solutions of salts, e.g.,calcium or lithium chloride, which are strong dehydrating agents .97The suggestion is made that the boric acid titration becomes possiblethrough dehydration.This may be so with glycerol, but scarcelyseems probable with mannitol, invert-sugar, and othcr compounds,seeing how small a concentration of these last is required.Mohr's chloride-silver titration can be carried out in faintly acidsolution (pH 5 to 7) by addition of a sodium acetate-acetic acid buffermixture to reduce the acidity.98 By treating a solution containingcyanides and halogen salts with sodium hydrogen carbonate andformaldehyde, the cyanides are eliminated as glycollates andhexamethylenetetramine, thus allowing the application of Volhard'smethod for halogens or thiocyanates in the usual way.g9 Reductionof chlorates in the presence of ferrous sulphate is most nearlycomplete (99%) in acid solution in the presence of potassiumiodide.1 A critical study of several different methods for theevaluation of chlorates has been made, with the result that all themethods, except one, were found satisfactory.2The accurate determination of small amounts of fluorine is awell-known analytical difficulty.Precipitation by calcium orthorium salts is unsatisfactory, for which purpose lanthanumacetate is now pr~posed.~ The process would, however, seem topresent certain difficulties, since a correction must be made foradsorbed precipitant.In the determination of large amounts of phosphoric acid by themolybdate-magnesia method, high or low results are obtainedaccording as the solution of the yellow precipitate in aqueous93 P.H. M-P. Brinton and A. E. Stoppel, J. Amer. Chem. SOC., 1924, 46,2454; A., 1925, ii, 72.s4 E. Wendehorst, 2. anorg. Chem., 1925, 144, 319; A., ii, 718.98 H. ter Meulen, Chem. Weekblad, 1925, 22, 80; A., ii, 330.O6 H. Funk and H. Winter, 2. anorg. Chem., 1925, 142, 257; A., ii, 714.9 7 M. Cikrtovit and K. Sandera, Chern. Liaty, 1925, 19, 179; A., ii, 714.@ * H. W. Doughty, J . Amer. Chem. SOC., 1924, 46, 2707; A . , 1925, ii, 238.ng E. Schulek, 2. anal. Chem., 1925, 66, 433; A., ii, 432.C. 0. Harvey, Analyst, 1925, 50, 538; A., ii, 1197.E. C. Wagner, 2nd. Eng. Chem., 1925, 17, 1183; A., ii, 1196.R. J. Meyer and M'. Schulz, 2. angew. Chem., 1925, 38, 203; A., ii, 698178 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.ammonia is acid or alkaline to litmus4 or more conveniently tobromothymol-blue,5 correct values being given a t the neutral point.Other chemists,6 however, find that the precipitate from neutralsolution is contaminated with magnesium molybdate and thenormal phosphate.As these writers obtain satisfactory pre-cipitation from slightly acid solution, it would seem that there issome further condition for precipitation not yet definitely laiddown. The Pemberton-Neumann method has been studied forthe purpose of eliminating errors,' and an improved method ofproducing a precipitate of magnesium ammonium phosphate freefrom other magnesium phosphates is described.8 Phosphates maybe rapidly determined by precipitation with silver nitrate in presenceof a slight excess of sodium acetate, the silver content of the pre-cipitate after dissolving in nitric acid being determined by titrationwith thi~cyanate.~Selenium may be quantitatively separated from tellurium byprecipitation by sulphur dioxide from cold solution of the twooxides in concentrated hydrochloric acid.1° Rydroxylamine hydro-chloride is found to be superior to hydrazine salts for the sameseparation, the oxides being dissolved in hydrochloric, tartaric, orcitric acid.llA rapid method of evaluating elementary sulphur is the oxidationwith hydrogen peroxide of the solution of sulphur in a, knownvolume of hot standard sodium hydroxide.12 Sulphites may bedetermined accurately by titration with iodate, free bromine,bromate, permanganate, or dichromate solutions containing iodide.13I n the absence of iodides, the amounts of bromate and dichromateused are less than those required for complete conversion of sulphiteinto sulphate, due, it is suggested, to the formation of dithionic acid.Iodate alone oxidises sulphites to sulphates ~omplete1y.l~ Methods4 J.M. McCandless and J. Q. Burton, Ind. Eng. Chem., 1924, 16, 1267;0 W. H. Ross, R. M. Jones, and A. R. Merz, J . Assoc. 08. Agric. Chem.,6 G. Jmgensen, 2. anal. Chem., 1925, 66, 209; A., ii, 824; R. J. Caro7 M. €3. Richards and W. Godden, Analyst, 1924,49,565; A., 1926, ii, 66;8 B. Schmitz, 2. anal. Chem., 1924, 68, 46; A,, 1925, ii, 67.s R. F. Le Guyon and R. M. May, Bull. SOC. chim., 1925, [iv], 37, 1291;10 V. Lenher and C. H. Kao, J .Amer. Chem. SOC., 1925, 47, 769; A., ii, 434.11 Idem, ibid., 2454; A., ii, 1199.18 F. Kiihl, 2. anal. Chem., 1924, 65, 185; A., 1925, ii, 156.13 W. S. Hendrixson, J. Amer. Chem. SOC., 1925, 47, 2156; A., ii, 1001.14 Idem, ibid., 1319; A., ii, 712.A., 1925, ii, 157.1925, 8, 407.and E. L. Larison, Ind. Eng. Chem., 1925, 17, 261.compare P. Nyssens, Bull. SOC. chim. Belg., 1925, 34, 232; A., ii, 1201.A., ii, 1202ANALYTICAL CHEMISTRY. 179are described for the volumetric determination of various sulphuracids in admixture.15Some notes on Nessler's solution have been published,16 and amodified reagent is described avoiding the use of potassium i0dide.l'Of various phenols tested, resorcinol and phloroglucinol alonecan replace phenol as fixing agents for nitrate nitrogen by theKjeldahl process in the absence of an accelerator.Even whenphenol itself is used, the potassium sulphate should not be addeduntil the first main reaction is completed.lsWater Analysis.For the detection of silicic acid in distilled water or sodiumchloride, potassium molybclate in nitric acid is added to the warmliquid. The green colour of the potassium silicomolybdate solutionmay be compared with that obtained from a standard sodiumsilicate solution. l9 I n many investigations, the presence of tracesof copper in water is undesirable. This metal may be detected indistilled water by adding a few drops of dilute hydrogen peroxidesolution followed by alcohol. A characteristic blue coloration isproduced, if copper is present, when a solution of alcohol-solubleguaiacum resin in pyridine is added to the water-alcohol mixture.The coloured substance is soluble in chloroform and ethyl acetate,the limit of sensitiveness is 1 in 108.20 Lead may be isolated fromwater for the purpose of colorimetric determination by precipitatingthe liquid with ammonia after addition of aluminium sulphate andsulphuric acid.21 An improved method of preparing the o-tolidinesolution for the determination of chlorine in chlorinated water isdescribed.22In comparing the dissolved carbon dioxide content of differentliquids, it has been found of value to determine the quantity of alkalinecessary to lower the hydrogen-ion concentration to a fixed level.The method of comparison chosen is that of determining the amountof carbon dioxide carried over when air is passed through thel5 A.Kurtenacker and K. Bittner, 2. anorg. Chem., 1924, 141, 297; 1925,142, 115, 119; A., ii, 239, 433, 434; E. Schulek, 2. anal. Chem., 1925, 65,352.l6 H. D. Richmond, Analyst, 1925, 50, 67; A., ii, 327; R. C. Frederick,ibid., 183; A., ii, 435.L. W. WinkIer, 2. Unters. Nahr. Qenussm., 1925, 49, 163; A., ii, 713.l8 B. M. Margosches and E. Scheinost, Ber., 1925, 58, [BJ, 1850, 1857;l9 R. Lorenz and E. Bergheimer, 2. anorg. Chem., 1924, 136, 95; A., 1925,2o G. Poirot, J. Pharm. Chim., 1924, [vii], 30, 393; A., 1925, ii, 242.21 W. W. Scott, Chem. News, 1925,131, 17; A., ii, 903.22 C. E. Roake, Id. Eng. Chem., 1925,17, 257; A., ii, 432.A., ii, 1094.ii, 600180 ANNUAL REPORTS ON THE PROGRESS OF CHENISTRY.different samples of water maintained a t a definite hydrogen-ionc~ncentration.~~ A form of flask has been described with theview of preventing the introduction of air when the reagents areintroduced into the water in Winkler's method for determiningdissolved oxygen.24 Nitrous acid, which interferes seriously withthis determination, may be removed by sodium azide.25A comparison of the Sorensen values of samples of sea-water ofknown salinity as determined by electrometric and colorimetricmethods using cresol-red has supplied the correction for the " salterror " of this indicator. Tables are given for the corrections tobe applied to the colorimetric determinations.26In solutions containing only small quantities of electrolytes,some indicators show a too acid reaction; for such solutions theindicators advised are a-naphthol-blue, cresol-red, neutral red,bromothymol-blue, bromocresol-purple, methyl-red, and methyl-orange.27#as Analysis.Several modifications of apparatus have been recorded fromamong which may be noted an improved form of the Bone andWheeler type with which samples of from 1 t o 5 ml.of gas may beaccurately analysed; 28 one in which the absorption vessel can bereadily detached from the burette and placed in a shaking machineso that four or five sets of absorption vessels may be used inrotation ; 29 and another for the accurate determination of smallquantities of hydrogen, methane, etc., in the presence of a, largeexcess of oxygen (or vice versa) in which the gases, after passingthrough a combustion chamber, enter a hair hygrometer, thealterations in the length of the fibre being an indication of thewater content, i.e., of the hydrogen or oxygen content of theoriginal gas.S0Attention is directed to the fact that oxidation of absorbedoxides of nitrogen by hydrogen peroxide in sodium hydroxidesolution-assumed in several recent researches to be complete-leads to formation of nitrite.For complete oxidation, the gasesare shaken in a closed bottle with acidified hydrogen peroxide for28 R. Legendre, Compt. rend., 1925,180, 1527; A,, ii, 714.$4 J. N. Friend, Chem. New8, 1925,130, 163; A., ii, 326.25 G. Alsterberg, Biochem. Z., 1926, 159, 36; A., ii, 1198.28 W.D. Ramage and R. C. Miller, J . Amer. Chem. SOC., 1925, 47, 1230;27 I. M. Kolthoff, Rec. trav. chim., 1925, 44, 275; A., ii, 596.2s D. S. Chamberlin and D. M. Newitt, Ind. Eng. Chem., 1925, 17, 621;29 11. N. J. Dirken, J . Scientific Instrument.9, 1924, 2, 55; A., 1925, ii, 154.3O L. Lowenstein, 2. physikal. Chem., 1924, 110, 799; A., 1925, ii, 154.A , , ii, 712.A., ii, 710ANALYTICAL CHEMISTRY. 1813 hours ; very small amounts such as occur (normally in the air orin products of combustion are separated by passing a measuredvolume of the gas through tubes cooled in liquid air, the con-densate being then oxidised as above for the purpose of deter-minati0n.~1Hydrogen and carbon monoxide are completely burnt to waterand carbon dioxide, respectively, whilst methane remains un-changed, when brought into contact with copper oxide a t 280-290".Mixtures of thew gases may thus be analysed, preferablyin a special gas pipette, which may be exhausted before introductionof the gases, so that errors due to absorption of air by the contactmass of ceric and copper oxides mamy be elirninat~d.~~The amount of carbon dioxide in a gaseous mixture may hdetermined by measuring the volume condensed by means of liquidair ; carbon monoxide is determined by oxidation, after removalof condensible gases, over heated iodine pentoxide, followed byliq~efaction.~~ Except in the case of fresh ammoniacal solutioncontaining not more than 5% of its volume of dissolved carbonmonoxide, cuprous chloride does not absorb this gas to complete-ness; 34 the slower absorption by cuprous oxide in sulphuric acidcontaining 8-naphthol may be hastened by using the reagent a t atemperature of about 60°.35A sensitive qualitative method for the detection of oxygen hasbeen devised dependent upon a coloration with pyrogallol andpotassium hydroxide ; nitrogen, hydrogen, acetylene, carbon mon-oxide, nitrous acid, nitric oxide, and ammonia do not interfere.36For another test, the oxygen is allowed to react with purified nitricoxide, the higher oxides of nitrogen affording a coloration with asulphuric acid solution of diphenylamine or with a dilute aceticacid solution of a-naphthylamine and sulphanilic acid.3' The com-pleteness and rapidity of absorption of oxygen by alkaline sodiumhyposulphite are increased by thc addition of 2yo of sodium anthra-quinone- 2-sulphonate .38Dilute ozonised air may be aiialysed with moderate accuracy byrapidly bubbling a large volume through potassium iodide, the31 A.G. Francis and A. T. Parsons, Analyst, 1925, 50, 262; A., ii, 713.32 J. Svdda, Chem. News, 1925, 130, 1; Chesn. Listy, 1925, 19, 41; A., ii,33 P. Lebeau and P. Marmmse, Compt. rend., 1925, 180, 1847; A., ii,34 H. R. Ambler, Analyet, 1925, 50, 167; A., ii, 436.3s T. C. Sutton and H. R. Ambler, ibid., 172; A., ii, 436.30 H. Schmdfuss and H. Werner, Ber., 1925, 58, [B], 71; A., ii, 238.Idem, J . pr. Chem., 1925, [ii], 111, 62; A., ii, 1198.38 Id. F. Fieser, J . Amer. Chern.SOC., 1934, 46, 2639; A . , 1926, ii, 238.154, 432.824182 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.iodine liberated being titrated with arsenite solution.comparison with standards is stated to be unsatisfa~tory.~~ColorimetricOrganic Analysis.Qualitative .-In cases of poisoning by formaldehyde, tests maybe applied directly to pieces of stomach wall ; 40 an intense magenta-red coloration with Schryver’s reagent is not, as hitherto supposed,specific for formaldehyde, since it is given by very small amountsof glyoxylic acid. The presence of formaldehyde in green leavescannot be considered as pr0ved.~1 Glycerol gives a positive color-ation in 0.04y0 solution by treatment with Schiff’s reagent, followingoxidation with ~ermanganate.~~Citric acid may be detected by oxidation with potassium dichrom-ate to acetone, which is identified by appropriate methods ; 43 andin the presence of tartaric acid by the blue coloration given withan acid solution of phosphomolybdic and vanadic acids.44 Lacticacid may be detected, e.g., in fruit juices containing other organicacids, by reason of the solubility of calcium lactate and the insolu-bility of the other calcium salts in 75% alcoho1.45The test €or acetone with sodium nitroprusside in ammoniacalsolution is most sensitive in the presence of ammonium sulphate ; 46full details of the colorations given by acetone and by acetaldehydewith nitroprusside in alkaline and acid solutions are tabulated .47Methylamine may be detected in the presence of large amountsof ammonia by the formation of dinitromethylaniline from chloro-2 : 4-dinitroben~ene.~8 A number of m-nitrobenzenesulphonamideshave been described as being particularly useful for the identificationof secondary amines .*9 The colour reaction following oxidationwith chromic acid serves to identify aniline and the three t o l ~ i d i n e s .~ ~Ammonia even in small amounts should be removed by aerationbefore application of the hypochlorite reaction for aniline.5139 H. von Wartenberg and G. von Podjaski, 2. anorg. Chem., 1925, 148,Jo C. Ghigliotto, Ann. Chim. Analyt., 1925, [ii], 7, 30; A., ii, 445.41 R. Fosse and A. Hieulle, Compt. Tend., 1924, 1’79, 636; A., 1925, ii, 162.42 I. M. Kolthoff, Pharm. Weekblad, 1924, 61, 1497; A., 1925, fi, 161.43 Rodillon, Repert. Pharm., 1924, 35, 233; A., 1926, ii, 246.4* W.Parri, Gioma. Chim. Ind. Appl., 1924, 6, 537; A., 1925, ii, 162.*5 A. Borntriiger, 2. anal. Chem., 1925, 66, 430; A., ii, 1007.4 6 H. W. van Urk, Pharm. Weekbkad, 1925, 62, 8; A., ii, 162.4 7 Idem, ibid., 2; A . , ii, 162.4 8 P. A. Valton, J., 1925, 127, 40.49 C. S. Marvel, F. L. Kingsbury, and F. E. Smith, J . Amer. Chem. XOC.,60 H. D. Murray, Chern. News, 1926,130, 23; A., ii, 163.6 1 E. S. West, Ind. Eng. Chem., 1924, 16, 1270; A., 1926, S, 163.391 ; A., ii, 1198.1925, 47, 166; A,, i, 244ANALYTIUAL CHEMISTRY. 183Tertiary amyl alcohol in sulphuric acid affords a colour rcactionwith tartaric acid and guaiacol,52 whilst benzyl alcohol may bedetected when present in fair proportion with hydrocarbons, alco-hols, ketones, etc., by conversion into benzyl ~ x a l a t e .~ ~A qualitative test for weak organic bases depends upon theformation of ferrichlorides upon interaction of the base and ferricchloride.54Various reactions are given for distinguishing the different alkylderivatives of barbituric acid used as hypnotics.55Colour changes are described for thirteen opium alkaloids whentreated in glacial acetic acid solution with basic magnesium hypo-chlorite and poured upon the surf ace of concentrated sulphuricacid.56 The melting points, solubilities, and microscopic appearanceof the picrates of several opium alkaloids are de~cribed.~'A blue coloration, characteristic of pentoses, develops when anaqueous solution of a pentose or of derivatives containing pentoseis poured upon a solution of P-naphthol in concentrated sulphuricacid.58 Pure glycyrrhizin, owing to its glucosidic nature, gives animmediate violet coloration in presence of sulphuric acid andaromatic hydroxyaldehydes.Pyrocatechol tannins give a heavy precipitate with nitrosomethyl-urethane, most pyrogallol tannins giving no precipitate.Whentreated twice with this reagent and then with iron alum and sodiumacetate, pyrogallol tannins develop a typical blue coloration, notgiven by pyrocatechol Two useful modifications of theferric citrate precipitation test for tannins have been described,61and also some notes on the identification of drugs containingtannins .62A greenish-blue colour test for Grignard reagent is obtained ontreatment with Michler's ketone, water, and iodine.63A comparative study has been made of the sensitiveness of thevarious tests for small amounts of a-naphthol in 6-naphthol; 64L.Ekliert, Pharm. Zentr., 1926, 66, 599; A., ii, 1006.53 A. S. Pfau, Perf. Ess. Oil Eec., 1925, 16, 190; A., ii, 905.54 R. Robinson, J., 1925, 127, 768.55 A. Zamparo, BOW. Chirn. Farm., 1926, 64, 257; A., ii, 907.6 G L. David, €'harm. Ztg., 1925, '70, 969; A., ii, 1010.G 7 C. W. Maplethorpe and N. Evers, €'harm. J., 1925,115, 137; A , , i, 1166.58 P. Thomas, BUZZ. SOC. Chirn. biol., 1925, 7, 102 ; A., ii, 604.G9 P. Bertolo, Giorn. Chim. Ind. Appl., 1925, 7, 404; A., ii, 1212.Go W. Vogel, CoZlegium, 1925, 189; A., ii, 827.G1 A.H. Ware, Analyst, 1925, 50, 335; A., ii, 905.c2 Idem, Pharm. J., 1925, 115, 131 ; A., ii, 1209.G3 H. Gilman and F. Schulze, J . Amer. Chem. Soc., 1925, 47, 2002; A , , ii,G4 T. Callan, J . SOC. Chem. Ind., 1925, 44, 1 2 5 ~ ; A., ii, 444.1011184 ANNUAL REPORTS ON r n ~ PROGRESS OF CHEMISTRY.these two substances may be differentiated by means of their colourreactions with sulphuric acid in alcoholic solution containinghydrogen peroxide and with formaldehyde in the presence of hydro-chloric acid.65 Benzyl-$-thiocarbamide forms salts with variousnaphthalenesulphonic acids, usually of definite melting point andsuitable for use as a means of identifying the acids.66&uantitative.-Numerous papers have appeared dealing with theultimate analysis of organic compounds, of which perhaps thc mostinteresting describes in detail a volumetric method for carbon andhydrogen in which the products of combustion other than carbondioxide and water vapour are removed by appropriate means.Reaction of the water with heated ‘‘ naphthyloxychlorophosphine,”C1,H,*P0C1,, liberates hydrogen chloride equivalent to the hydrogenin the substance; the gases are washed with a small volume ofwater to retain the hydrogen chloride, and the carbon dioxide isabsorbed in excess of standard barium hydroxide.Titration of thehydrochloric acid gives the hydrogen content of the substance, andtitration of the excess of barium hydroxide gives the carbon content.Details of the apparatus and preparation of the reagents are given.67Descriptions of the chromic acid oxidation 68 and of a rapid calori-metric bomb method are furnished.69 Following oxidation of anorganic compound with potassium iodate and sulphuric acid (thecarbon dioxide evolved being determined in the usual way), a deter-mination of the excess of iodate affords data for calculating thecomposition.7O Modifications of well-known methods for carbon,hydrogen, and nitrogen consist in the use of manganese dioxide a t400” and upwards 71 and in combustion with copper oxide in avacuum. 72If the decomposition of hydrazine in alcoholic potash solutioninto nitrogen and hydrogen by a catalyst prepared from palladiumchloride be carried out in the presence of an organic halogen com-pound, the halogen is eliminated and can be determined.73 Sodiumarsenite in alkaline solution may be used as a reagent for looselycombined halogen.,46 5 A. Zamparo, BoU.Chim. Farm., 1925, 64, 97; A., ii, 444.6 6 R. F. Chambers and P. C. Scherer, J . Ind. Eng. Chem., 1924, 16, 1272;67 J. Lindner, 8. anal. Chem., 1925, 66, 305; A., ii, 901.A., 1925, i, 127.J. W. White and F. J. Holben, Ind. Eng. Chem., 1925, 17, 83; A., ii,240; A. Desgrez and R. Vivario, Compt. rend., 1925, 180, 886; &4., ii, 436.69 H. D. Wilde, jun., and H. L. Lochte, J . Amer. Chem. SOC., 1925, 47, 440;A . , ii, 600.i o G. Vortmann, 2. anal. Chem., 1925, 66, 272; A., ii, 827.71 J. Heslinga, Rec. trav. chim., 1924, 43, 551; A., 1925, ii, 65.72 J. &Veda and 0.ProEke, Chem. Listy, 1925, 19, 163; A., ii, 719.i 3 31. Busch, 2. angew. Chem., 1925, 38, 519; A., ii, S23.74 A. Gutma,nn, 2;. ana2. Chem., 1924, 65, 246; A., 1925, ii, 238ANALYTICAL CHEMISTRY. 185The nitrogen in oil, coke, and proteins is converted quantitativelyinto ammonia by admixture with sodium carbonate and heatingin a current of moist hydrogen a t 100"; v 5 catalytic hydrogenationis similarly applied to organic nitrogen compound^.^^Destruction of organic matter with 30% hydrogen peroxide priorto the determination of inorganic poisons in viscera, etc., isdescribed ; 77 whilst a rapid method for the determination of arsenicin organic compounds depends upon decomposition with ammoniumpersulpha te . 8The important matter of determining oxygen in certain organicsubstances is again dealt with by a modification of the catalytichydrogenation method.The procedure is applied to organiccompounds containing nitrogen, sulphur and halogens. 7'3Formaldehyde readily reacts with potassium hydrogen sulphitewith formation of a neutral sulphonate, so that excess of the reagentmay be determined by titration with standard alkali hydroxide.8oWith potassium cyanide, the product first formed is the potassiumderivative of glycollonitrile, the hydrolysis of which is' acceleratedby magnesium sulphate. The excess of cyanide is titrated withsilver after the precipitated magnesium hydroxide has been dissolvedby addition of ammonium chloride. 81The conditions for the determination of tartaric acid in the formof its calcium salt are set out,g2 and this acid may be determinedby oxidation with a measured excess of dichromate.The lattermethod is applicable to sucrose, p-naphthol, salicylic and phthalicacids .83Acetylation of 2 : 4-dichloroanilii1e, which has already been usedby Orton for determining small amounts of acetic anhydride inglacial acetic acid, has now been adapted to the evaluation of theanhydride through the dichloroa~etanilide.~~A method for the determination of small quantities of lactic acidis based on the formation of acetaldoxime when the acid is distilledwith SOYo sulphuric acid and the distillate is passed into hydroxyl-amine.85 Acetone may conveniently be determined in the presence76 H. ter Meulen, Rec.trav. chim., 1925, 44, 271 ; A , , ii, 599.76 Idem, ibid., 1924, 43, 643; A., 1925, ii, 66.7 7 G. Magnin, J . Pharm. Chim., 1925, [viii], 1, 333; A., ii, 594.7 8 G. Newbery, J., 1925, 127, 1751.H. ter Meulen, Rec. trav. chim., 1924, 43, 899; A., 1925, ii, 166.8o G. Romeo, Ann. Chim. A p p l . , 1925, 15, 300; A., ii, 1009.*l E. Schdek, Ber., 1925, 58, [B], 732; A., ii, 606.82 M. Franpois and C. Lormand, J . Pharm. Chim., 1924, [vii], 30, 27G;83 K. Tiiufel and C. Wagner, 2. anal Chem., 1925, 67, 16; A., ii, 1007.A., 1925, ii, 75.W. S. Calcott, F. L. English, and 0. C. Wilbur, Ind. Emg. Chem., 1925,P. Leone and C. B. Tafuri, Ann. Chim. Appl., 1925, 15, 206; A., ii, 907.17, 942; A., ii, 1007186 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of alcohol by a vapour pressure method,8s whilst the 2 : 4-dinitro-phenylhydrazone may be used for the determination of very smallquantities in urine.8'Directions are given for the elimination of the interfering cyan-amide derivatives in the determination of cyanamlde,88 the calciumcompound of which can be assayed by treatment, after hydrolysis,with methylxanthhydrol, whereby xanthylcarbamide is producedand weighed.89The requisite conditions for the determination of oleic acid byconversion into dihydroxystearic acid have now been workedCinchonine as a tannin precipitant is of particular value in theanalysis of cutch and gambier, since the catechin, which is largelyabsorbed by hide powder, is not affected.g1From a potentiometric study of the titration of various alkaloids,methyl-red is recommended as indicator for strychnine, brucino,morphine, codeine, nicotine, hydrastine, atropine, and cinchonine ;methyl-orange for narcotine ; and p-nitrophenol for quinine, withappropriate buffer solutions in the last three instances.92 Similarresults for some other alkaloids are given el~ewhere.~3 Mixtures ofmorphine, narcotine, and codeine, titrated with silicotungstic acidby a conductometric method, give curves showing points of inflexioncorresponding with successive precipitation of the alkaloids.g4Novocaine may be determined colorimetrically in the presence ofseveral allied substances, by the colour formed on mixing withsolutions of sodium nitrite, hydrochloric acid, and sodium carbonatecontaining potassium guaiacolsulphonate ; sodium hydrogen sulphiteshould be removed before diaz~tising.~~ The blue condensationproduct with vanillin given by trytophan in presence of concentratedhydrochloric acid may be applied to determination of the amino-a ~ i d .~ 6 A filtered acid extract of suprarenal powder mixed withsolutions of sodium acetate and mercuric chloride produces in thepresence of adrenaline a red coloration which can serve for colori-metric comparison with a standard solution of z~drenaline.~'86 E. A. Vuilleumier, Ind. Eng. Chem., 1925, 17, 174; A., ii, 246.88 L. A. Pinck, Ind. Eng. Chem., 1925, 1'7, 459; A,, ii, 607.89 R. Fosse, P. Hagene, and R. Dubois, Contpt. rend., 1924, 179, 408;9O A. Lapworth and E. N. Mottram, J., 1925, 127, 1628.9 1 D.Hooper, Analyst, 1926, 50, 162; A . , ii, 443.92 H. B. Rasmussen and S. A. Schou, Pharm. Zentr., 1924, 65, 729; A.,C. Biilow, Science, 1925, 61, 344; A,, ii, 1210.A., 1925, ii, 761925, ii, 247.F. Miiller, 2. Elektrochem., 1924, 30, 587; A , , 1925, ii, 607.94 F. E. Raurich Sas, Anal. Pis. Quim., 1925, 23, 277; A., ii, 1011.OG P. Cheramy, J . Pharm. Chim., 1924, 30, 408; A , , 1925, ii, 247.O6 I. Kraus, J . Biol. Chem., 1925, 63, 157; A , , ii, 448.9 7 0. Bailly, J . Pharm. Chim., 1924,30, 404; A., 1925, ii, 248ANALYTICAL CHEMISTRY. 187A procedure devised to fulfil conditions considered best isdescribed for the determination of the copper number in the chemicalanalysis of cotton,98 also a method to circumvent the fact thatcopper numbers obtained from alkali-soluble celluloses by Schwalbe’smethod are not comparable with values similarly obtained fromalkali-insoluble celluloses, on account of the sensitiveness of theformer to the action of hot alkali.99Since appreciable errors may be incurred in the volumetric deter-mination of reducing sugars on account of copper sulphate penta-hydrate containing excess of moisture, Fehling’s solution shouldbe standardised against invert-sugar.l Superheating causes anerror which may be avoided by addition to the mixture of Fehling’ssolution and assay liquid of an inert powder to promote regularebullition -2Possible errors in Schoorl’s method for the determination ofinvert-sugar in liquids containing sucrose have been investigated ;allowance must be made for the fact that the sucrose reducesFehling’s solution to an extent diminishing with increasing quan-tities of this compound.3 Modifications have also been made bythe author of the method.4All carbohydrates, etc., that give hexoses on hydrolysis yield, ondistillation with 12 yo hydrochloric acid, hydroxymethylfurfur-aldehyde, so that the determination of pentosans by this methodmay leadl to erroneous results. A procedure for regulating thedistillation so as to yield fairly good results is given in some detail.5A lengthy paper deals with the determination and formation ofhydroxymethylf urfuraldehyde.6The influence of a number of substances such as chlorides andalkaline earths on the reducing action of dextrosc has been inves-tigated,’ and the interaction of dextrose and methylene-blue hasbeen placed on a quantitative basis.8Two descriptions of methods for the determination of chlorine inbenzaldehyde are given, one using a bomb calorimeter for the com-s8 D.A. Clibbens and A. Geake, J . Text. Inst., 1924, 152, 27; A., 1926, ii,906.ss K. Hess, Annalen, 1924, 440, 290; A., 1925, ii, 245.J. H. Lane and L. Eynon, J . SOC. Chem. Ind., 1925, 44, 150.1.; A., ii, 445.L. Pick, Z . Zuckerind. Czechos~ov., 1925, 49, 211,219,235,243; A., ii, 906.M. A. H. van den Hout, P. A. Neeteson, and A. L. van Scherpenberg,Chem. Weekblad, 1924, 21, 578; 1925,22, 126; A., ii, 74, 446; C. J. de Wolff,ibid., 78; A., ii, 245; C. van der Hoeven, ibid., 79; A., ii, 331.N. Schoorl, ibid., 132, 285; A., ii, 445, 828.F.W. Klingstedt, 2. anal. Chem., 1925, 66, 129; A., ii, 720.E. Troje, 2. Ver. Deut. Zucker Xnd., 1925, (828), 635; A., ii, 1210.P. Fleury and P. Tavernier, Bull. Soc. Chim. biol., 1925, 7 , 331; A , , ii,60.5; L. Rosenthaler, Pharm. Zentr., 1925, 66, 517; A., ii, 1006.* E. Knecht and E. Hibbert, J. SOC. Dyers Col., 1925, 41, 94; A , , ii, 606;188 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.b ~ s t i o n , ~ the other involving the gradusl distillation of comparativelylarge quantities of the aldehyde from iiitrosulphuric acid.1° Bothmethods claim great accuracy.Methods are described for the analysis of various mixtures ofphenol nitration products. These depend upon the bromineabsorbed and on the formation of nitron picrate.llAqueous solutions of aniline may be titrated with O.1N-sulphuricacid, using bromophenol-blue, p-dimethylaminoazobenzene, orCongo-red as indicator, the first being best.With the toluidines,results are less satisfactory.12An extensive and detailed review has been made of many methodsof determining mnillin, piperonal, and coumarin when alone or inadmixture. l3As the result of a critical investigation of the Hochst test fordetermination of anthracene, revised directions are now given.l4Anthracene may be determined in anthraquinone by a colorimetriccomparison of the charring which occurs on heating anthracenewith oleum, the comparison being made with colour standardsprepared from potassium dichromate and cobalt ch10ride.l~Physical Methods.From a consideration of the absorption constants of the twotautomeric forms of an indicator assumed to be in equilibrium andof the ionic dissociation of the indicator, it is concluded that wherethe pH value is dot extremely small, it should be a simple functionof the absorption ratio and independent of the concentration ofindicator, so that a tedious calibration is unnecessary.This isfound to be the case with so-called “ normal ” indicators such ascresol-red and bromothymol-blue ; crystal-violet and methyl-red,however, are classed as “abnormal,” in that there is a markeddeviation from the simple relationship expected.16 Work on the“ apparent ” dissociation constants of indicators has been extendedto thymol-blue, bromocresol-green, and sodium a-naphthol-2-sulphonate indophenol.l79 J. D. Bukschnewski, 2 . angew. Chem., 1925, 38, 723; A,, ii, 1000.10 T. H. Faust and T. Spiingler, Chem. Ztg., 1925, 49, 724; A., ii, 1000.11 1;. Desvergnes, Ann. Chim. Analyt., 1925, [ii], 7, 35, 65, 97; A., ii, 447,la C. M. Carson, Ind. Eng. Chem., 1925, 17, 62; A., ii, 447.l3 L. G. Radcliffe and E. H. Sharples, Perf. Ees. Oil. Rec., 1924, 15, 396,14 F. H. Rhodes, M. L. Nichols, and C. W. Morse, Ind. Eng. Cltem., 1925,15 H. P. Lewis, ibid., 1924, 16. 1184; A., 1925, ii, 74.l o F. Vlbs, Compt. rend., 1925, 180, 654; A., ii, 595. Compare W. R.17 W. C. Holmes and E. I?. Snyder, J. Amer. Chem. SOC., 1925, 47, 221,607.437; 1925, 16, 20, 51, 87, 156, 197, 271, 353, 387; A., ii, 1210.17, 839; A., ii, 1005.Rrode, Ann.Report, 1924, 21, 152.226, 2232 ; A., ii, 325, 999PLNALYTICAL CHEMISTRY. 189The spectrophotometric method has been examiiied with theidea of utilising the method as a, quantitative measure of substancesoxidisable by potassium permanganate. l8 The blue colour obtainedwith hydrochloric acid and solutions of cobalt is due to an absorptionspectrum of four bands, easily perceptible a t great dilution with adirect-vision spectroscope. This has been utilised to determinetraces of cobalt in nickel salts.19Traces of gold, down to in minerals or isolated by appro-priate means from solutions, may be detected by an examination ofthe arc and spark spectra. The line 2428.1 A. is considered themost suitable line of the spark spectrum for the detection of gold.20Quantitative methods of analysis with the aid of X-rays aredescribed.One method takes account of the relative intensitiesof the photographed spectrum lines; 21 another is a modificationof the method of determining the proportion of a metal in a mixtureof oxides containing it by adding known weights of another oxideuntil the intensity of one of its lines in the X-ray spectrum coincideswith that of the corresponding line in the spectrum of the metal theproportion of which it is desired to determine.22 This procedure hasbeen utilised to determine hafnium in zirconium materials, orzirconium in hafnium compounds.A strong collodion diaphragm, resistant to-a pressure of 40 atmo-spheres, is described for physico-chemical analysis of solutions.Itis built up of fine wire, surrounding an artificial silk envelope, whichin turn covers an enamelled metal tube pierced by small holes.23A t great dilutions, proteins such as egg-albumin will prevent thelowering of the surface tension of water by sodium oleate, andthis may be utilised for detecting minute quantities of proteins insolution .24When a solution containing sodium hydrogen tartrate andammonium molybdate is treated with a potassium salt, the reactionof the latter with the tartrate results in depression of the opticalrotation of the liquid, the extent of this depression serving as ameans of determining the amount of potassium added.25Additional mixtures of thallium salts (formate, malonate, andfluoride) have been prepared which allow of thc separation ofminerals of all specific gravities between 1 and 5.4.26H.Gombos, Biochem. Z., 1924, 151, 1 ; A., 1925, ii, 237.G. Denighs, Compt. rend., 1925, 180, 1748; A., ii, 826.2o P. Joliboisand R. Bossuet, Bull. SOC. chim., 1925, [iv],37,1297 ; A., ii, 1208.2 1 P. Giinther and G. Wilcke, Annalen, 1924, 440, 203; A., 1925, ii, 237.22 D. Coster and Y . Nishina, Chem. News, 1925, 130, 149; A., ii, 324.23 E. Fouard, Ann. Chim. Analyt., 1925, [ii], 7 , 33; A., ii, 324.24 P. L. du Nouy, Science, 1925, 61, 472; A., ii, 1212.2 s A. Wr6be1, Roczniki Chemji, 1924, 4, 287; A., 1925, ii, 240.28 E. Clerici, A$ti R. Amad. Liruei, 1956, [vij, 1, 329; A., ii, 694190 ANNUAL REPORTS ON m E PROURESS OB CHEMISTRY.Electro-chemical Methods.Electrolytic.-An economic rotating anode of thin platinum wireon a glass stirrer is described, which, although unsuited to methodsin which lead is deposited on the anode as peroxide, can be usedunder proper conditions for the successive deposition of copperand lead in the metallic state.Attention is directed to the unsuit-ability of anodes of large surface and oxidising power in certainelectro-analytical methods.27 Further work has been carried outon the use of graded potentials for the electrolytic separation ofvarious metals.28The solvent action of nitrous acid on electro-deposited leaddioxide may be overcome by addition of carbamide towards theend of the simultaneous electrolytic deposition of copper and lead.29Conditions have been worked out for the rapid electrolytic separationof tin from tungsten.This important separation is effected in thesolution containing excess of alkali sulphide by adding Rochellesalt and potassium hydroxide, followed by hydrogen peroxide andphosphate, and final electrolysis a t 60-70°.30 Copper is separatedcleanly from tin, antimony, and lead by the use of nitric and tartaricacids,31 whilst an adherent deposit of antimony may be obtainedfrom chloride solution in the presence of tartaric acid and hydrazine~ u l p h a t e . ~ ~Indium is deposited from acid or alkaline solutions on a dropping-mercury cathode. The reaction is reversible and requires a cathodicpotential of 0.503 volt for deposition of the metal from a molars0lution.~3 Nickel may be determined accurately in the presenceof chromium and iron from alkaline solution by the addition ofammonium oxalate and ammonium citrate.% Under no conditionswas it found possible to deposit nickel from oxalate electrolyteswithout some contamination by organic matter, although, in thecase of iron, contamination may be retarded sufficiently to allowof quantitative deposition by the addition of ammonium chloride.35EZectrometric.-Numerous papers dealing with electrometrictitrations and modifications of the electrometric methods have beenpublished. Several convenient types of calomel electrode have27 A.Lassieur, Bull. SOC. chim., 1924, [iv], 35, 1530; A., 1925, ii, 154.Idem, Comnpt.rend., 1924, 1'99, 632, 827; Ann. Chim., 1925, [x], 3, 235;A., ii, 159, 328, 711.29 H. Biltz, Ber., 1925, 58, [B], 913; A., ii, 715.30 A. Jilek and J. Lukas, Chm. =8tY, 1924, 18, 205; A., 1925, ii, 242.31 Idem, ibid., 378; A,, ii, 241.32 A. Schleicher and L. Toussaint, Chem. Ztg., 1925, 49, 646; A,, ii, 1004.33 J. Heyrovsky, Chem. LiSty, 1925, 19, 168; A., ii, 717.34 E. Rousseau, CJbim. et Ind., 1925, 13, 199; A., ii, 441.35 P. K, Frolich, AnaZyst, 1925, 50, 224; A., ii, 604ANALYTICAL CHEMISTRY. 191recently been described,36 whilst both hydrogen gas and a calomelcell can be dispensed with by combining a pure graphite electrodewith a platinum spiral electrode through a millivoltmeter. Thepotential is given as + 0.18 volt for 0-O1N-acid and - 0.73 for0.01N-alkali.37An antimony electrode may be employed where the hydrogenelectrode is inadmissible, e.g., in determining free acid in thepresence of oxidising agents.38 The use of two electrodes, polarisedby a constant potential of 0.2-1 volt applied with a large resistancein series, is recommended for electrometric analysis, since an abruptalteration in potential difference occurs at the e n d - p ~ i n t .~ ~ Modi-fications of the application of the three-electrode valve to electro-metric work have been made.40A simple differential method of electro-titration consists indivision of the solution to be titrated into two parts, platinum wiresconnected to a millivoltmeter being immersed in each. The twosolutions, also connected with a strip of filter-paper, are simul-taneously titrated, one burette being always kept 0.2 ml.ahead ofthe other. At the end-point, the voltmeter readings suddenlyattain a maximum, curves for the maximum being unnece~sary.~~For the potentiometric standardisation of titanous chloridesolutions, a solution of copper sulphate, free from iron and ofstrength determined accurately by electrolytic deposition, is recom-mended.42 The method can be applied to the determination ofcopper in the presence of mercury, lead, cadmium, zinc and arsenic.Titanous chloride titrations, followed potentiometrically, may beapplied also to determining vanadium, antimony, uranium, molyb-denum, selenium,43 and indirectly to manganese, e.g., in iron ores.44Bismuth solutions can be readily titrated by reduction from thetervalent condition by means of titanous chloride; the best resultsare obtained in 3% hydrochloric or in acetic acid solution, sodiumchloride and tartaric acid being added to prevent precipitation of36 C.J. Schollenberger, Ind. Eng. Chern., 1925, 17, 649; A., ii, 711; H. C.Parker and G. A. Dannerth, ibid., 637; A,, ii, 712.37 J. C. Brunnich, ibid., 631; A., ii, 711.38 I. M. Kolthoff and B. D. Hartong, Rec. trav. chim., 1925, 44, 113; A,, ii,39 R. G. van Name and F. Fenwick, J. Amer. Chem. SOC., 1925, 47, 19;40 K. G. Goode, ibid., 2483; A., ii, 1196; W. D. Treadwell and C. Paoloni,c1 D. C. Cox, J. Amer. Chern. SOC., 1925, 47, 2138; A., ii, 999.42 E. Zintl and A. Rauch, 2. anorg.Chem., 1925,146, 281; A., ii, 1003.43 0. TomiZek, C h e n ~ Listy, 1924, 18, 210, 233; A., 1925, ii, 243.44 A. McMillan and W. C. Ferguson, J . SOC. Chem. Ind., 1925, 44, 1 4 1 ~ ;325.A., ii, 694.Helv. Chim. Acta, 1925, 8, 89; A,, ii, 595.A . , ii, 441192 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.basic bismuth chloride and titanic acid, re~pectively.~5 By appro-priate modifications, the method may be applied to the determin-ation of bismuth in the presence of iron, lead, tin, cadmium, andarsenic, but not in the presence of antimony.46 A similar reductionoccurs with gold, which may be determined in presence of mercury,tin, lead, and copper; in presence of iron, a considerable amountof phosphoric acid should be added.47Stannous and antimonious chlorides may be titrated by potassiumdichromate in hydrochloric acid solutions, using the oxidation-reduction electrode to indicate the end-point ; the antimony maybe titrated separately, after addition of mercuric chloride.4* Theiron-dichromate titration is applied to the determination of ferrousand ferric iron in rnagnetite~.~~ The potentiometric determinationof chromium and vanadium in presence of each other has beendescribed and applied to the analysis of steel; 50 also to the deter-mination of tervalent cerium by oxidation of the cerous sulphateor chloride in a concentrated potassium carbonate solution.Forthe latter case, an oxygen-free atmosphere is necessary, and thetitration is effected by potassium ferricyanide.51A sudden large change in the potential occurs in the reactionbetween the halogens and potassium cyanide when the theoreticalquantities for the formation of cyanogen halide are pre~ent.~2 Asolution of mercurous perchlorate gives better results than thenitrate in the titration of chlorides or bromides, using a mercuryelectr0de.5~ Details are given for the electrometric titration ofhypochlorous acid, with comparison electrodes of neutral salts orfeeble oxidising agents,54 and of chlorous acid, particularly inpresence of the hypochlorous acid. 55Curves for the titration of hydrazine salts with bases are verysimilar t o that obtained with ammonium hydrogen sulphate; thereaction of hydrazine with iodine and with potassium bromate wasalso followed, as well as the complete oxidation of hydroxylamineto nitrate.5G45 E. Zintl and A, Itauch, 2. anorg. Chem., 1924,139, 397; A., 1925, ii, 442.46 Idem, ibid., 1925, 146, 291; A , , ii, 1004.47 Idem, ibid., 1925, 147, 256; A., ii, 1005.4 8 M. H. Fleysher, J. Amer. Chern. SOC., 1924, 46, 2725; A., 1925, ii, 243.49 H. R. Adam, J. S. Afr. Chem, Inst., 1926, 8, 7 ; A., ii, 717.60 I. M. Kolthoff and 0. Tomi&ek, Rec. truv. chim., 1924, 43, 447; A., 1925,61 0. Tomizek, ibid., 1925, 44, 410; A., ii, 716.53 E. Miiller and A. Schuch, 2. Elektrochem., 1925, 31, 332; A., ii, 825.53 C. Miiller and H. Aarflot, Rec. truv. c?km., 1924, 43, 874; A., 1925, ii, 65.54 ,4. Schleicher and L. Toussaint, 2. anal. Chem., 1925, 65, 399 ; A., ii, 433.h5 A. Schleicher and W. Wesly, ibid., 406; A., ii, 433.ii, 72.E. C. Gilbert, J. Arner. C’hem. Sac., 1924, 46, 2648; A., 1926, ii, 239ANALYTICAL CHEMISTRY. 193Between the limits pH 2-05 and 8-0, accurate determinations of thepH may be much more rapidly made by replacement of the hydrogenof a platinum-hydrogen electrode by quinhydrone added to thes0lution.~7 The ordinary hydrogen electrode may be replaced by asmall platinised platinum cathode set in a solution of which the pEis required and to which a small polarising current is applied until theevolution of bubbles just commences. This method is particularlyadvantageous for alkaline solutions.6* Of a number of metals andoxides tested for suitability to replace gas electrodes in measuringhydrogen-ion concentrations, the most promising were electrodes oftungsten-manganese sesquioxide and platinum-manganese sesqui-0xide.~9 J. J. Box.B. A. ELLIS.6 7 H. Niklas and A. Hock, 2. angeso. Chem., 1925, 38, 407; A., ii, 595.59 H. C. Parker, Ind. Eng. Chem., 1925, 17, 737; A,, ii, 899.S. Glasstone, Analyst, 1925, 50, 327; A , , ii, 822.REP.-VOL. XXU.

ISSN:0365-6217    

DOI:10.1039/AR9252200168

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

BIOCHEMISTRY.Introduction.THE same arrangement of subject matter has been adopted in thisReport as in that for the previous year, namely, soil chemistry,plant biochemistry, and animal and general biochemistry. Oncemore this results in the inclusion in the first part of the Report ofmuch matter that cammot strictly be termed biochemistry ; owingt o the importance of modern views on the inorganic and physicalchemistry uf the soil, and the undesirability of separating thediscussion of this from that of other bra.ncheo of soil chemistry,this anomaly is inevitable.Apart from the appearance of a few papers of outstandingimportance, the year under review is not marked by any radicaladvcznce in knowledge. No attempt has been made to cover thewhole field in detail, but a few of the more important subjects havebeen selected for special discussion.The I n o r g a n i c Colloids of the Xoil.The Weathering Process.IN recent Reports emphasis was laid on the important part playedby the colloidal aluminosilicates in soil phenomena ; attention wasdirected in the Report for 1923 to the work of Bradfield,l whichshowed that this inorganic colloidal material consisted of a definitecompound or mixture of compounds and not of a mixture of thehydrates of silica, alumina, and ferric oxide. Evidence of a similarnature was advanced by Gedroiz.2 Little is known at present withregard to the nature of the chemical reactions involved in the pro-duction of natural alumiiiohydrosilicates from the parent rock inthe prccess of weathering.R. Schwarz and R. Walcker3 haveadvanced a theory according to which transition of felspar intokaolinite consists first in the decomposition of the mineral into itscomponents : K,0,A1,03,6Si0, + 2KOH + 2A1(OH),+6Si02aq ;under special conditions the products reunite to form kaolin or anintermediate product. They show that aluminium hydroxide and1 Ann. Reports, 1923, 20, 201.Editorial Cttee. of the People’s Cornissariat of Agric., Leningrad, 1922.2. anorg. Chew&., 1025, 145, 304; A., ii, 887BIOCHEMISTRY. 195silicic acid in an aqueous medium in the proportion 1A120, : 6Si02precipitate a substance of the composition A1,0,,2Si02,2H20, whichon keeping becomes similar to kaolin. The most favourable zoneof reaction for complete precipitation is a t pH 443--5.0.A largeexcess of silicic acid remains in the solution, since the ratio ofalumina to silica in the precipitate is 1 : 2. According to theseworkers, therefore, the natural formation of kaolin, and thereforeprobably also of the other aluminium hydrosilicates in soil, is not dueto an ionic reaction, but to the mutual coagulation of aluminiumhydroxide sol and silicic acid sol. It must be admitted that,although Bradfield’s results showed conclusively that the syntheticmixture he used was quite distinct from the natural colloid, thepossibility that under suitable conditions the mutual precipitationof alumina and silicic acid might finally result in a definite compoundwas not tested in his work; the results of Schwarz and Walckershow that this may occur, although it has still to be proved that itactually does so in nature.It is well known that the type of product produced by weatheringis largely dependent on climatic conditions.R. Ganssen hasrecently published it summary of his views on the nature of theessential reactions involved in the chief types of weathering ofaluminosilicate rocks.4 He distinguishes three main types :“ Clay weathering,” which occurs under humid conditions in coldand temperate zones. Here the reaction consists, in the case ofpotash felspar, in the production of a mixture of a zeolitic silicate ofthe general composition 4-6Si02,A1203,K20,mH20 with a kaoliniticsilicate, 2Si02,A1203,2H,0, together with soluble potassium silicate,3-6Si02,K20,nH20, which is washed away and lost.Under semi-humid conditions in temperate and tropical zones, “ laterite weather-ing ” occurs. This may be true lateritisation in which the inter-mediate formation of a zeolitic silicate, 6Si0,,A1203,1<20,nH,0, isfollowed by the complete elimination of silica and potash in theform of soluble potassium silicate, 6Si02,K20,nH20, leaving behindhydrargyllite, A1203,3H20, the end-product of weathering in truelaterite soils. Alternatively, “ clay laterite ” weathering mayoccur, in which, parallel with the above lateritic process, a part ofthe felspar is converted into kaolinitic silicate which is not furtherchanged. Finally, there is the type of weathering which occurs inarid and semi-arid zones, termed ‘‘ hydration-weathering. ” Herethe chemical changes are a t a minimum.There is no leachingout of soluble products, and the chief reaction is one of hydrationonly, the felspar being converted by the addition of water into a,Mitt. aus den Lab. der PreussiFchen Geolog. Lasdes amtal., Heft 4,Berlin, 1922.a196 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.zeolitic silicate, 6Si0,,A120,,K20,~H20. I n another papery5 Ganssendeals with the production of loess soils, where the weathering is ofthe hydration type. The origin, distribution, and composition oflaterites are dealt with in a paper by C. 0. Swanson.6The reactive aluminosilicates of the soil differ in many respects fromtrue kaolinite; although there is no evidence for the occurrence oftrue zeolites in soils and clays, it is clear from recent work that thereactive inorganic colloids of the soil behave in a similar way tozeolites or permutites with regard to the ionic exchange and absorp-tion phenomena which they exhibit.A. Demolon' regards thereactive aluminosilicates of quaternary clays as zeolitic silicates with akaolinic nucleus, thus recalling van Bemmelen's well-known divisionof the weathered silicates in the soil into " complex A " (decom-posable by hydrochloric acid) and " complex B " (not decomposedby hydrochloric acid but decomposed by strong sulphuric acid),the latter being often referred to as of a kaolin-like nature.A careful study of the process of weathering of granite in theHarz mountains has been carried out by E.Blanck and H. Paterson.8From an analysis of the material soluble in hydrochloric acid fol-lowed by extraction with soda (" complex A "), they find valuesfor the molecular ratio of K,O : SiO, which range from 1 : 1.6 to1 : 2.9 and show marked fluctuations rather than a continuousgraduation as the degree of weathering increases. They concludethat the usually accepted value of 1 : 3 for this ratio in the weatheringcomplex of the soils of temperate regions is not well founded, andthat the value of " complex A " and of the molecular ratio ofalumina to silica as a means of characterising the type of weatheringhas been much exaggerated.Mention may also be made of other papers on the formation andproperties of zeolites, clays, and substances with a permutoids t r u ~ t u r e .~Soil ClassiJication.I n recent years, much attention has been directed to the relationbetween base exchange in soils and such questions as the formationof alkali soils and soil acidity. No apology is made for again layingemphasis on this aspect of the soil, since there appears to be a growingbody of evidence to indicate that many of the most important6 L O C . cit.8 J . Landw., 1924, 71, 181.9 0. Weigel, Sitzungsber. Ges. Beforder. ges. Naturwiss. Jlarburg, 1924, 73;A., 1925, ii, 709; G. Shearer, Trans. Ceram. SOC., 1923-1924, 23, 314; A.,1925, ii, 698; H. Kautsky end G. Herzberg, 8. anorg. C'hem., 1925, 147,81; A., ii, 941; G. N. Ridley, Chem. News, 1925,131,305; A., ii, 1130.J .Amer. Cemnz. Soc., 1923, 6, 1248.Compt. rend., 1925, 181, 673; A., ii, 1195BIOCHEMISTRY. 197chemical and physico-chemical changes in the soil can be satis-factorily interpreted in terms of ionic equilibrium and ionic exchangesassociated with the colloids of the soil. K. K. Gedroiz lo hasrecently published an interesting paper in which he has shown howthe relation between many of the chief soil types can be explainedfrom a consideration of the nature and amount of the exchangeablekations in soils. He divides soils into two main types according towhether they do or do not contain absorbed hydrogen in theirabsorbing complex. Soils of the latter type, which he termssaturated soils, are further subdivided according to the nature of theexchangeable base.In the tsernosem type, this is mainly calciumwith some magnesium; such soils are relatively stable and are butlittle affected by the peptising or dissolving action of water. Whenscdium is present in addition to calcium thero are threc possibilities :(a) saline soils (“ solontshak ”) containing dissolved sodium saltsin their water ; ( b ) alkaline soils ( ‘ I solonetz ”), where, owing to theabsence of appreciable quantities of dissolved neutral salts, theexchangeable sodium gives rise to alkali by hydrolysis. Whenthe absorbing complex is saturated with sodium it breaks downreadily under hydrolytic influences, so that in the absence ofchalk in the soil it gives rise to the third type, (c) (“ soloti ”), inwhich there has occurred an actual loss of a part of the absorbingcomplex, to an extent comparable with the alkalinity of the alkalinesoil from which it is derived.If, however, chalk is present, thisloss does not occur, and as the sodium is removed as carbonate,calcium re-enters into the complex to give a soil not differingmarkedly from the original soil, from which the alkaline soil wasderived by the action of sodium salts.Soils of the other main group contain absorbed hydrogen in theirabsorbing complex. They owe their characteristics to the fact thatthe absorbing complex, when markedly unsaturated with bases,shows a pronounced tendency to decompose and give rise to a com-plex of a new type; this tendency is, however, not so great as in thecase of alkali soils, where all the products of decompositioii of thecomplex may be washed away.Two types are distinguished :(a) laterite soils, in which there has been a sharply defined destruc-tion of the absorbing complex throughout the whole depth, withabundant accumulation of alumina and ferric hydroxide, and amarked impoverishment in silicic acid; ( b ) podsols, in which thedecomposition of the absorbing complex is confined to the surfacelayers of the profile, and the impoverishment in silicic acid is lessthan in the case of laterites.lo Nossov Agricultural Experiment Station, Agrochemical Div., PaperNo. 38, Leningrad, 1926198 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Gedroiz’s work refers chiefly to Russian soils, but most of theother recognised soil types can be referred to one of the abovedivisions or to intermediate stages between them.Another factorthat must be taken into account in any complete classification is theamount and character of the soil organic matter; here there aremany problems awaiting investigation.In .one respect Gedroiz’s views are not quite in accord with thoseof some other soil investigators. In referring to soils of the firstgroup discussed above as “ saturated,” he appears to consider thata soil with a neutral or slightly alkaline reaction is free fromexchangeable hydrogen. As a matter of fact, the inorganic colloidalmatter of the soil can go on ta.king up bases up to a reaction ofpR 10-11 ; similarly, a neutral salt will bring about a lowering ofpH in a soil even on the alkaline side of neutrality.As statedin last year’s Report,ll these facts can be explained by assumingthat the whole of the exchangeable hydrogen of the soil is replacedonly a t a pE of 10-11, and that for the attainment of neutralityit is sufficient for only a fraction of the total exchangeable hydrogento be replaced by basic kations. This distinction between themeaning of the term “ saturated ” as originally applied to the soilby Ramann, and its significance according to one modern school ofthought, is discussed by H. J. Page and W. Williams in the latterpart of a paper dealing with the exchangeable bases of Rotharnstedsoils . laThe Relation between Flocculation and Base Exchange.The flocculation of clay and soil suspensions and the physico-chemical factors controlling the physical condition of the soil aresubjects on which a large amount of work has been carried outduring the last twenty or thirty years, and very conflicting viewshave been advanced regarding the nature of the processes involved.Recent investigations on this subject, however, have to some extentcleared up the difficulties in this field, and have brought the pheno-mena more nearly into line with modern views on the nature of thereactive colloids of the soil.The marked variations in the flocculating power of neutralsalts according to the valency and atomic weight of the metal ofthe salt, which were investigated by A.D. Hall and C. G. T. Mor-rison several years were most exhaustively studied by Ged-roiz.14 The differences observed can be correlated with the veryl1 Ann.Reports, 1924, 21, 177, 183.12 Tram. Paraday SOC., 1924, 20, 1.14 Communication 24, Bureau of Agr., Scientific Committee of Main Dept.l3 J. Agric. Sci., 1907, 2, 244.of Land Organisation, 1915. St. PetersburgBIOCHEMISTRY. 199great variation in the physical state of suspensions of clay, accordingto the kation with which it is saturated. Clay saturated withcalcium is relatively hydrophobic and settles to a compact sediment,whereas clay saturated with sodium is very hydrophilic and pro-duces a very voluminous, jelly-like mass.15 G. Wiegner l6 hasshown, in a paper of outstanding importance, characterised by theelegance of the experimental methods used and by the soundness ofits theoretical basis, that a satisfactory and convincing explanationof these phenomena can be found in the variations in the degree ofhydration of the kations of the neutral salts used or with which theclay is saturated.The nature of the electrical double layer and themanner in which it is influenced by the hydration of the ions in theouter layer are first considered. When the mobile ions of the outerlayer are highly hydrated, they cannot approach so near to theinner layer, so that the effective distance between the two layersis increased and the potential of the inner layer increases. Thehigher the potential, the greater the stability, so that we shouldexpect the stability of a series of clays to increase in the orderH clay, Cs clay, Rb clay, K clay, NH, clay, Na clay, Li clay,and Ba clay, Sr clay, Ca clay, Mg clay,if we accept the usual order for the hydration of the various ions.From this it is easily seen that base exchange, by altering theion in the outer layer, can materially alter the stability of thesuspension.We should also expect that the most effective pre-cipitating ions would be those which are least hydrated, since theycan get nearer to the inner layer than heavily hydrated ions, andso can lower the potential more. We should expect a lithium clay,for instance, to be flocculated by the other ions in the followingorder, the least active ones coming first :Na', K., NH,', Rb', Cs', H'.The ion in the outer layer determines to a certain extent whetherthe clay tends to be hydrophobe in character or hydrophile, accord-ing as it is hydrated to a lower or greater extent.The differencebetween univalent and bivalent kations depends, not only on thedifference in charge, but also on the difference in their degrees ofhydration. These ideas were experimentally tested as follows.For otherwork on this subject see also G. Wiegner, R. Galley, and H. Gessner, ibid.,1924, 35, 313; A., 1925, ii, 3 6 ; R. Galley, Helv. C'him. Acta, 1924, 7 , 641;L. C. Wheeting, Soil Sci., 1925, 20, 363; R. Ed. Liesegang, Sprechsaal, 1923,56,513 ; 0. Nolte and E. Sander, Land. Vers.-Stat., 1924,102,219; E. Ramann,Soil Xci., 1924, 18, 387; A , , 1925, i, 223,1 5 K. K. Gedroiz, Zhur. Opit. Agron., 1924, 22, 29.16 Kolloid-Z., 1925, 36, Zsigmondy-Festschr., 341 ; A., ii, 527200 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Coagulation experiments were carried out by the ultramicroscopiccounting method.The percentage decrease in the number ofparticles after a given time was determined for five different con-centrations of electrolyte. Clays in which the bases had been com-pletely replaced by sodium, ammonium, potassium, and calciumwere used. The sensitivity to potassium chloride for the variousclays was in the converse order from the above, i.e., the sodium clayrequired the most potassium chloride for a given reduction in thenumber of visible particles. The order was the same for calciumchloride, which always flocculated better than potassium chloride.The determination of the comparative degrees of hydration wascarried out using an Ostwald viscosimeter, the assumption beingmade that the hydration will show itself in increased viscosity.TheViscosity rose in the series Ca, K, NH, and Na clay, but the rise wasnot large. A calcium or a potassium clay being used, the time takento reach a maximum viscosity when coagulation was effected withthe same quantity of different chlorides (a quantity insufficient forcomplete discharge being used) was determined. It was found thatthe more hydrated was the kation of the clay, the less sensitivewas the clay in the region of slow coagulation. The coagulationoccurs the more quickly the less hydrated are the coagulating ionsso long as they are of the same valency.Slight traces of alkali hinder the flocculation of clay by neutralsalts, although in higher concentrations alkalis have the oppositeeffect of facilitating flocculation.These facts can be interpreted onthe assumption that clays can absorb hydroxyl ions. Such absorp-tion was thought by Michaelis to occur; and in the work of S. E.Mattson, this process is invoked to explain the effect of alkalis onflocculation by multivalent ions. Mattson l7 made the importantdiscovery that in this flocculatlion there is usually little actualneutralisation of the charge on the particles. Clay particles withabsorbed hydroxyl ions are supposed to attract calcium ions, whichact as a link between adjacent particles. The floccules thus consistof smaller particles carrying hydroxyl ions and are held together bya sort of cement of calcjnm ions.As will be clear in the following discussion on Kappen’s views, thereality or not of this postulated ability of soil colloids to absorbhydroxyl ions is a crucial question in judging the rival views regard-ing the nature of soil acidity.It is much to be hoped that furtherwork on this subject will be forthcoming. If the view of the soilcolloids as colloidal aluminosilicic or humic acids is a correct one,it is somewhat difficult to understand why such electronegativeacidic material should absorb negative hydroxyl ions; it would in1 7 ?-oil. Chcm. Reihcfte, 1922, 14, 227BIOCHEMISTRY. 201many ways simplify matters if the influence of alkalinity on floccula-tion could be satisfactorily explained purely in terms of the kationicexchange which suffices for most of the other physico-chemicalphenomena of soil colloids.Further evidence that the absorptionof kations by the soil is to be regarded as a chemical process isafforded by P. N. Pavlov.ls The absorption of dyes by soils, whichhas often been proposed as a method of measuring the amount ofcolloidal matter in the soil, has been shown by J. A. Wilkinson andW. Hoff l9 to partake of the nature of a base exchange between thedyes and the bases in the soil; similarly, the absorption of saltsof organic bases by calcium permutite and by clay has been foundby E. Ungerer 2O to depend on base exchange. A. M. Smith 21 haspublished an investigation on the exchangeable bases in someScottish soils.The importance of exchangeable bases in the soilin relation to the supply of nutrient materials to the plant is wellillustrated by the interesting results obtained by A. von Nostitz.22It was found that when several agricultural plants were grown insand cultures they made far better growth when calcium, magnesium,and potassium were supplied in the form of their permutite complexesthan when they were supplied as soluble salts.The Nature of Soil Acidity.There is no diminution in the bewildering number of papersthat are published on soil acidity, and much confusion of thoughtstill exists with regard to this subject. The most prominent Germanworker on this subject is Kappen, whose views have received widealthough not unanimous support in German~.~3 Kappen dis-tinguishes four types of soil acidity which he appears to regard asdistinct phenomena.When a soil becomes sour owing to depletionof lime, the first type of acidity to develop is called by Kappen" hydrolytic acidity." This is manifested by the fact that treat-ment with sodium acetate solution gives rise to acidity in the liquid.This Kappen explains by assuming that in an only mildly de-calcified condition, the soil can take up the base of a hydrolysedsalt, leaving the free acid in solution. This it is supposed to do byl8 Kolloid-Z., 1925, 36, 78; A., ii, 281.lo J . Phgsical Chem., 1925, 29, 808; A , , i, l i 2 7 .2o Kolloid-Z., 1925, 36, 228; A., ii, 058.21 J. Agric. Sci., 1925, 15, 466.22 Landw.Vem.-Stat., 1925, 103, 159.23 H. Kappen, 2. Pflanz. Dung., 1924,3A, 200; A., 1925, i, 221 ; H. Kap-pen and K. Bollenbeck, ibid., 1925, 4A, 1 ; H. Kappen and R. W. Beling, ibid.,1925,6A, 1 ; E. Kurclrmann, ibid., 1925,5A, 1 ; A., i, 1032 ; 0. Lemmermann,J. Hudig, H. Niklas, 0. Nolte, D. J. Hissink, R. Ganssen, and E. Ramann, ibid.,1325, 48, 222, et seq.U202 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.absorbing the hydroxyl ion, which takes the sodium ion with itand thus the equilibriumis moved to the right.The next type of acidity to develop in the soil is called ‘‘ exchangeacidity ” ; a soil possessing this type of acidity gives an acid solutionwhen treated with a neutral salt, and since, as shown previously byDaikuhara, aluminium is then present in the liquid in an amountsufficient to account for the observed acidity on the assumption thatthis is due to the hydrolysis of aluminium chloride, Kappen regardsthis acidity as due to the direct exchange of aluminium with thekation of the neutral salt, this aluminium being present in the soilsilicates in the kationic condition.The next and more severe typeof acidity to develop is called by Kappen “neutral salt decom-position ” ; in this case, the addition of a solution of a neutral saltresults in a still higher hydrogen-ion concentration, not necessarilyaccompanied by an equivalent amount of aluminium, especiallyin the case of humic soils. This is again explained by assumingthe absorption of hydroxyl ions, which is supposed to be increasedby the presence of the neutral salt; the hydroxyl ion takes thekation of the neutral salt with it, and the hydrogen-ion concen-tration in the liquid increases accordingly. Finally, “ activeacidity ” develops in a soil entirely depleted of exchangeable ba.ses.It is to be noted that Kappen and his supporters admit thepresence of zeolitic or permutoid aluminosilicates in the soil;moreover, they regard the absorption of hydroxyl ion and kationwhich they postulate in the case of “hydrolytic acidity” and“ neutral salt decomposition ” as being merely intermediate tothe actual chemical combination of the kation with the silicate.However, they reject the explanation of Hissink and van der Spek z4and of GedroizYz5 according to which, by regarding hydrogen as anexchangeable kation, most of the phenomena of soil acidity can berationally and simply explained.Although considerable spacewas devoted to this section of the subject in last year’s Report,the persistence in some quarters of views of the type held by Kappenis sufficient excuse for devoting further space to the subject here.We know that the collgidal matter of soils has a definite affinityfor kations, and a tolerably well-defined saturation capacity ;moreover, the lower the degree of saturation with basic kations,the more acid is the soil. The work of Bradfield has providedCH3*C0,Na + H,O NaOH + CH3*C0,H24 D. J. Hissink and J. van der Spek, Chern. Weekblad, 1925, 22, 500; A., i,1525 ; J. van der Spek, Onderzoekingen der Rijkdandbowproefstations, 1922,162; D.J. Hissink, 2. Pflanz,. Dung., 1925, 4A, 137; A., i, 490.25 Zhur. Opit. Ayrm., 1924, 22, 3BIOCHEMISTRY. 203strong reasons for regarding the colloidal matter of the soil as trulyacidic in nature.26 Since this colloidal acid exists in the gel formon the surface of soil particles, we cannot apply ordinary stoicheio-metric formulie to the whole system of aluminosilicic acids andassociated kations. It is, however, possible to represent the con-dition a t varying degrees of saturation of the acid of the colloid on apercentage basis. Thus if x% of the total saturation capacity of acolloidal acid is neutralised by basic kations, we may write this asXR' [complex] (lOO-x)H* ; the whole range between complete saturationand complete desaturation is represented byxR' -.- [Complex] 100 H'.(100-x) H' --- [Complex] 100 R' + [Complex]The left-hand formula corresponds to the " normal " salt, theright-hand one to the free acid, and the intermediate formula to thewide range of " acid salts.'' We know that the state of completesaturation corresponds to a high pH value of about 10 or 11 andthat complete desaturation corresponds to a low p H of the order of3 - 5 4 . When R iscalcium, Hissink's results indicate that neutrality, pH 7, corre-sponds to a value of about 55 for x for many soils. The differentforms of soil acidity of Kappen can be rationally explained in termsof the variation of the value of x in the above formula. The higherthe value of x, the smaller will be the percenta,ge of hydrogen in thecomplex which is capable of exchange with other kations, and hencethe lower will be the equilibrium concentration of hydrogen ion inthe liquid when the soil is treated with a soluble salt.Hence in asoil with a comparatively small proportion of acidic hydrogen inthe colloidal phase, the salt of a "strong " acid such as hydro-chloric acid could only bring about a minimal amount of ionicexchange between the kation and this ionic hydrogen, since a verysmall amount of titratable acidity in the form of hydrochloric acidwould be sufficient to give rise to the small equilibrium concentra-tion of hydrogen ion in the liquid. By using the sodium salt of itweak acid, however, oonsiderably more acidic hydrogen can beexchanged for sodium before the same hydrogen-ion concentrationis reached in the liquid, since this concentration represents a muchhigher titratable acidity in the case of a weakacid like acetic acid.Only in the case of more highly desaturated soils, in which the valueof z is much lower, is the amount of acidic hydrogen in the colloidhigh enough for ionic exchange with the salt of a strong acid likeThe higher the value of x the higher is the p H .26 Ann.Reports, 1924, 21, 175. See also W. H. Pierre, Soil Sci., 1925, 20,285; A., i, 1526; A. do Dominicis and S . Dojmi, Annal. Chim. Appl., 1926,15, 183.Q* 204 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.hydrochloric acid to give an appreciable titratable acidity.Kap-pen’s distinction between exchange acidity and neutral salt decom-position rests mainly on the production of soluble aluminium in theformer case.27 The arguments used by Kappen against the viewthat this aluminium arises as a result of secondary reactions are notvery convincing. Space does not allow for a detailed discussionof this side of the question, which will be dealt with by the Reporterelsewhere, but granting such secondary reactions in the productionof soluble aluminium it is clear that the various forms of aciditydefined by Kappen can be consistently and simply explained asbeing all manifestations of the same acidic property of the soilcolloids, differilig only in degree and not in nature. It seemsunnecessary to resort to somewhat complicated explanations involv-ing the affinity of an electronegative colloid for the negative hydroxylion, when the known affinity of the colloid for positive kations,whether metallic or hydrogen, suffices to explain the phenomena.I n practice, one of the most important requirements is to deter-mine the amount of lime that must be added to render a sour soilsuitable for crop-growfh-that is to say, its so-called “ limerequirement.” As pointed out last yearY28 this is by no meanssynonymous with the amount of lime required to bring the soil toneutrality.Further evidence has been advanced that in manycases the harmful effects of soil sourness are due to deficiency ofcalcium rat,her than to actual acidity.29 Moreover, some workershold the view that the presence of soluble aluminium may beresponsible for infertility in some cases (see below).I n such cases,the lime requirement from the agricultural point of view is theamount of lime needed to remedy the lime deficiency or to removesoluble aluminium, not to render the soil neutral.I n any case, the amount of base required to bring the reaction ofthe soil to any given point is determined far less by the actualhydrogen-ion concentration of the soil suspension than by the bufferaction of the soil.30 Hence the study of the titration curves of soilsuspensions is of importance. This subject is dealt with together2 7 H. Niklas and A. Hock, 2. Pfzanx. Dung., 1925,5A, 370; A., i, 1525;A. Sokolov, J . Landw.- Wissensch. Moskau, 1924, 1, 411 ; L.Smolik, Compt.rend., 1925,180, 1773; A., i, 1032.28 Ann. Reports, 1924, 21, 183.29 A. Densch, Hunnius, and Pfaff, 2. Pflanz. Dung., 1924,3B, 248 ; A. Densch,ibid., 1924, 3A, 218; A., 1925, i, 221; G. W. Robinson and R. Williams,Trans. Paraday SOC., 1925, 20, 1; A., i, 222. J. R. Fleetwood, Soil Sci.,1925, 19, 441.30 J. Charlton, Mem. Dept. Agric. India, 1924, ‘7, 111; A., 1925, i, 768;E. W. Bobko and D. W. Druschinin, 2. Pflanz. Dung., 1925, 5A, 345; A., i,1525BIOCHEMLSTRY. 205with many other important questions in relation to soil reactionin an interesting series of papers by Crowther 31 which should beread in the original.Attention may also be directed to several papers dealing with thechanges undergone and caused by lime in theThe InJ'uence of #oil Reaction on Plant Growth.Several papers have been published dealing with the relationbetween the reaction of the soil and the growth of various agricul-tural crops.These serve to emphasise the well-known fact thatcrops vary widely in their sensitiveness to soil acidity. Thus thework of C. Olsen33 shows that although the optimum range of pHfor lucerne (6.5-7.0) differs but little from that for rye (6.0-6.5)or for buckwheat (6-0-7.0), the first-named crop gives 13% of itsoptimum growth in a soil of pH 4.0, whereas buckwheat and ryea t this reaction still give 90% and 82%, respectively, of the growtha t optimum pE. Olsen's work also shows in common with that ofM. Tr6nela that the majority of plants prefer a slightly acid orneutral reaction, and that excess alkalinity has a far greater de-pressing effect than has excessive acidity.0. Arrhenius,35 who hasalso investigated the growth of common farm crops in soils of vary-ing reaction, claimed to show that the curves illustrating therelationship between plant growth and the pH of the soil invariablyhave two maxima, but Olsen 33 could find no evidence for this in thecase of lucerne. Arrhenius36 could find little evidence that theinfertility of acid soils is often due to aluminium, since toxic quan-tities of this element are usually only detectable in very acid soils.This point has been specially investigated by 0. C. Magistad,37who has shown that more than three parts of alumina per millioncan be present in a soil solution only when the reaction is outsidethe range of p H 4-7-8-0.Important papers on the effects of soilacidity on plants have also been published by H. Kappen,38H. I C i r ~ t e , ~ ~ and A. Sch~ckenberg,~~ although in these cases the31 E. M. Crowther and W. S. Martin, J . Agric. Sci., 1925, 15, 237; A., i,876; E. M. Crowther, ibid., pp. 201, 222, 232; A., i, 875.32 F. Scheffer, J . Landw., 1925, '72,201; A , , i, 624; E. Blanck and W. Loh-mann, 2. Pflanz. Dung., 1924, 3A, 91; A., 1925, i, 223; E. Blanck andF. Scheffer, ibid., 1925, 4B, 66; A., i, 491; A. Gehring and C. Schulcke, ibid.,113; A. Gehring, ibid., p. 70; W. Renner, ibid., p. 417; A. Gehring and0. Wehrmann, Landw. Ver8.-Stat., 1925, 103, 279; A., i, 1031.33 Compt.rend. Trav. Lab. Carlsberg, 1925, 16, 1.34 2. Pflanz. Dung., 1925, 4B, 340.35 Ibid., 1925, 4A, 30; A., i, 490.3 7 Soil Sci., 1925, 20, 181; A,, i, 1371.38 2, Pflanz. Dung., 1925, 4A, 202; A., i, 874.39 Ibid., 1926, 5A, 129. 40 Ibid., 1924, 3A, 65.36 Ibid., p. 348 ; A., i, 766206 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.conclusions are somewhat, confused by the classification of acidityinto different types, as already mentioned on page 201.R. E. Neidig and H. P. Magnuson41 have published a series ofpapers dealing with the relative toxicity of the various salts, com-monly found in " alkali soils," to a number of agricultural crops.Nitrogen and Carbon Cycles i n the S o i l .Humic Matter.Of the many hypotheses that have been advanced with regardto the origin and mode of formation of humic acid, the ligninhypothesis of Fischer and Schrader 42 continues to attract anincreasing amount of attentioh.On the whole, the balance of theevidence appears to be in its favour. One of the principal opponentsof this hypothesis is J. Marcusson, who regards oxycellulose as theparent substance of humic acid.43 The most important argumentadvanced by him against the lignin hypothesis is based on the factthat sphagnum peat contains more than 40% of humic acid,although the sphagnum from which it is formed is stated to containvery little lignin. This is an argument that cannot be lightlydisregarded, and further work 011 the constituents of sphagnummoss and its humification is badly needed in order to clear up thispoint.In another paper, Marcusson 44 advances further arguments infavour of his assumption that humic acid contains furan nuclei.0.Burian45 also has described experiments purporting to demon-strate the formation of furfuraldehyde from humic acid, but thevalidity of his methods has been questioned by W. Eller,46 whoreasserts his opinion 47 that artificial humic acids prepared fromcellulose are not identical with natural humic acids.C. Wehmer 48 has advanced further evidence that in the decom-position of lignified tissues by fungi the cellulose disappears andthe lignin is converted into humic substances.Studies of the changes in farmyard manure during maturation androtting in the soil have been carried out by R.Balks49 and byE. BottiniY5O but although they provide interesting data on therelative rates of disappearance of various constituents (pentosansS . Vhgi, Biochem. Z . , 1925, 158, 357; A., i, 1023.4 1 Soil Sci., 1924, 18, 449; 1925, 19, 115; 20, 376; see also D. FBher and42 Ann. Reports, 1924, 21, 172.44 Ber., 1925, 58, [B], 869; A., i, '793.45 Brennstog-Chem., 1925, 6, 52; A., i, 372.46 Ibid., p. 55; A., i, 372.4 8 Brennstog-Chem., 1925, 6, 101 ; A , , i, 521.49 Landw. Yew.-Stat., 1925, 103, 221; A., i, 1031.Eo Annal. Chim. AppZ., 1925,15, 346.43 2. angew. Chent., 1925, 38, 339.Ann. Reports, 1923, 20, 200BIOCHEMISTRY. 207appear to be most rapidly attacked), they do not throw any directlight on the question of the parent substance of humic bodies.Wheeler and his co-workers have published further work on thehumic substances (or as they prefer to term them, ulmins) in coal.51As investigations on this subject and on soil humic substancesproceed, it is probable that an increasing number of points of contactwill develop.In a paper by S.A. Wak~man,~2 special attention is directed to theso-called " neutral humus " obtained by neutralisation of the acidfiltrate from the main humic precipitate produced when an alkalinesoil extract is acidified. This material, which has a high ash content,is soluble in both acids and alkalis. It appears doubtful, however,whether this fraction of the soil organic matter, which occurs inrelatively small amounts, is of any great significance, althoughWaksman attaches some importance to its effects in the soil.The Carbon-Nitrogen Ra.tio.Addition to the soil of carbohydrate material, or generally, oforganic substances of high C:N ratio, such as straw, has an im-portant effect on the amount of available nitrogen in the soil andtherefore on crop growth.53 There are good reasons for ascribingthis influence to the fact that in the presence of an excess of organicmaterial the soil organisms are in a position to multiply, providedthat there is available to them sufficient nitrogen for the synthesisof their cell protoplasm.Further papers on this subject, whichserve to strengthen this view, although they bring forward no newfacts of outstanding importance, have been published by T. L.Martin,54 T.L. Lyon, J. A. Bizzell and B. D. Wilson,55 and Ger-lach.56 In a paper by W. A. Albrecht and R. E. UhlandYs7 atten-tion is directed to the indirect effects of changes in moisture contentand aeration induced by a straw mulch, which must be taken intoaccount in their influence on nitrate content in addition to thedirect effect of carbohydrate derived from the straw.Of direct bearing on the relations between carbohydrate decom-position and nitrogen availability in the soil are the results ofH. Heukelekian and S. A. W a k ~ m a n , ~ ~ who have studied thedecomposition of cellulose by two typical soil fungi. They found61 W. Francis and R. V. Wheeler, J., 1925, 127, 2236; F. V. Tideswell andR. V. Wheeler, ibid., pp. 110, 125.62 Proc.Nut. Acad. Sci., 1925, 11, 463; A., i, 1528.63 Ann. Reports, 1923, 20, 241.64 Soil Sci., 1925, 20, 159; A., i, 1372.5 5 J . Arner. SOC. Agron., 1924, 16, 396; A., 1925, i, 347.b6 2. Pflanz. Dung., 1925, 48, 534.5 7 Soil Sci., 1925, 20, 253. J . Biol. Chem., 1925, 66, 323208 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.that the cellulose was completely decomposed by the organisms andcould be fully accounted for by the carbon dioxide evolved and thecarbon assimilated and built up into fungal tissue. The carbon andthe nitrogen assimilation bore a definite relationship to each other.A direct correlation thus exists between the amount of cellulosedecomposed and the amount of nitrogen transformed into insolubleorganic form .On the basis of relationships of this sort, Waksman 59 has ad-vanced an interesting explanation of the well-known and strikingfact that in most cultivated soils the C : N ratio is relatively constant,seldom showing more than small divergences from a value of about10.This Waksman explains by supposing that the C : N ratio ofthe organic matter of the soil, as a product of the action of soilorganisms, is controlled by the definite relation between the amountof carbonaceous matter assimilated by the soil organisms and theamount of nitrogen built up int,o their cells a t the same time.Any excess of nitrogen beyond the amount required for the assimila-tion of the carbon available will be converted into a soluble form andbe lost from the soil by leaching or by absorption by the roots ofplants.Thus the complete transformation of organic matter addedto the soil involves the passage of the whole of the carbon andnitrogen finally appearing as soil organic matter, through the stageof micro-organic cell material of fixed C : N ratio, with the necessaryresult that the C : N ratio of the whole of the resulting organicmatter is fixed within narrow limits. This explanation is, on theface of it, it very attractive one, and it seems almost inevitablethat in the process of decomposition of organic matter by soilorganisms such regulatory mechanism must operate. This is,however, not the whole story, for no account is taken of the extra-ordinary stability of the nitrogen compounds of the soil. Despitethe presence in the soil of innumerable protein-splitting, ammonify-ing, and nitrifying organisms, and of conditions favourable to theiraction, the bulk of the organic nitrogen of the soil is very resistantto degradation.The amount of nitrate and ammonia in the soilis never under ordinary conditions more than a small percentage ofthe total nitrogen. There are good grounds for believing that mostof this nitrogen is present in an unorganised form, i.e., not in theform of cell protoplasm of living organisms, in which condition itwould, of course, be immune from extensive breakdown. Yetaccording to Waksman’s hypothesis the nitrogen all passes throughthe stage of micro-organic protoplasm, and after the death of the5s J . Agric. Sci., 1924, 14, 555.e0 Compare H.Strrtche, H. Zikes, and G. Polcich, 2. Pflanz. Dung., 1925,6A, 66BIOCHEMISTRY. 209micro-organisms, of protein.00 Why is this protein not rapidlyattacked and broken down to ammonia and nitrate? It is clearthat if it persists in the soil in the form of protein it must be pro-tected in some way from the further action of micro-organisms,except at a very slow rate.Recent work in the Reporter’s laboratory at Rothamsted byR. P. Hobson 61 has provided definite evidence for the existence ofthe greater part of the soil nitrogen in the form of protein; more-over, it has been shown that this protein is associated with thehumic matter of the soil. This humic matter as ordinarily pre-pared always contains about 4% to 5% of nitrogen and has a C : Nratio not far removed from 10.Hitherto the form in which thisnitrogen exists has been a matter of much doubt; it was uncertainwhether it was an integral constituent of the humic acid moleculeor merely present as an associated impurity.The work of Hobson appears to indicate that the soil containsa humic matter-protein complex of tolerably constant composition.This would explain why the carbon-nitrogen ratio of the soil varieswithin fairly narrow limits and moreover the association of theprotein with the humic matter can easily be conceived as pro-tecting the former in some way from the action of micro-organisms.The small amount of nitrate and ammonia ordinarily present in thesoil would represent the breakdown of the small proportion of thetotal protein liberated by the slow oxidation of the associated humicmatter.Much further work is needed before this view can be fullyaccepted, but it provides a reasonable explanation of the knownfacts.Combining this view with that which supposes the origin ofhumic matter from lignin, we can envisage the course of the conver-sion of organic residues into soil organic matter as consisting oftwo converging series of changes. The fist consists in the con-version, whether by biological or purely chemical agencies is notyet known, of the lignin in these residues into humic matter; thesecond involves the conversion of the non-lignin constituents (mainlycarbohydrate and protein) into micro-organic protein. The productsof these two serieb then combine to give a humic matter-proteincomplex which is resistant to biological degradation and of approxi-mately constant composition.A useful survey of recent work on soil biochemistry is containedin a paper by Waksman 62 based on an extensive tour of most of thelaboratories of Europe in which work on soil microbiology is inprogress.61 Ph.D.(London), Thesis (not yet published).Soil Sci., 1926, 19, 201210 ANNUAL REPORTS ON !I'H.E PROGRESS OF CHEMISTRY.The Effect of Soil and Other Factors on Plant Crowth.The R61e of Silica in Phnt Nutrition.The striking results obtained by Lemmermann in his investiga-tions of the effect of colloidal hydrated silica on the yield of plantsgrown on media deficient in phosphates have been to some extentexplained by further work.It will be remembered that in theReport for 1922 63 the Reporter questioned the validity of Lemmer-mann's conclusion that the observed effects of colloidal silica weredue to its ability to replace phosphates in the plant, and pointed outthat analytical data for the relative amounts of silica and phosphoricacid taken up by the plants were required in order to decide therelative merits of Lemmermann's explanation and the one alreadyadvanced to account for the older Rothamsted results, according towhich the action of silica was an indirect one, in which the phosphateuptake by the plant was increased by the silica. 0. Lemmermann,H. Wiessmann, and K. Sammet 64 have now published the resultsof a further investigation, in which the required analytical resultsare forthcoming.These show quite definitely that the favourableaction of silica is correlated with an increased assimilation of phos-phoric acid by the plant. Lemmermann therefore abandons hisearlier views, and explains his results by the older hypothesis, towhich these later results quite definitely point, namely, that thesilica exerts a solvent action on the phosphate present in the soiland renders it more easily available to the plant. His coiiclusionswere criticised by E. Duchon, but Lemmermanii in his reply65satisfactorily answered these criticisms. Densch 66 and Gile andSmith6' also have obtained evidence of the action of silica inincreasing the availability of phosphates to the plant .68The In$uence of Boron on Plant Growth.The striking work of Miss Waringt~n,~~ which demonstrated thenecessity of small traces of boron for normal growth of manyleguminous plants, has been extended by Miss W.E. Brenchleyand H. G. Thornton.'O These workers ha\-e shown that small tracesof boron (1 : 500,000 parts of boric acid) are necessary for the proper63 Ann. Reporta, 1922, 19, 215.64 2. Pflanz. Dung., 1925, 4A, 265; A., i, 766; H. Wiessmann, ibid., p. 73.6 5 F . Duchon, ibid., p . 316; 0. Lemmermann, ibid., p. 326; A . , i, 767.66 Landw. Jahrb., 1924, 60, 142; A., 1925, i, 767.6 7 J . Agric. Res., 1925, 31, 247.6 8 See also D. R. Nanji and W. S. Shaw, J . SOC. Chem. Ind., 1925, 44, 1 ~ ;89 Ann. R e p o h . , 1923, 20, 219.70 Proc. Roy. Soc., 1926, 98, B, 373; A., i, 1368.A., i, 214BIOCHEMISTRY.211development of root nodules and that in the absence of boron thevascular supply of the nodules is defective. The nodules, insteadof supplying nitrogen compounds to the plant, tend to becomeparasitic, attacking the protoplasm of the host plant.Stimulants of Plant Growth.For many years past, somewhat surprising claims have beenadvanced on the Continent, particularly by Popoff, that considerableincreases in the yield of crops could be brought about by treatmentof the seeds with a great variety of chemicals. Several papers onthis subject have appeared during the past year.71 If the effectsclaimed are real, and if they can be cheaply and easily obtained,it would be a matter of considerable economic importance, but a tpresent the evidence cannot be regarded as entirely satisfactory.Many of the experiments demonstrate at the most that improvedgermination and growth of seedlings results ; in the absence of morecomprehensive tests, this cannot be accepted as evidence that theyields of the crops at maturity would be similarly improved.It is claimed that moderate dressings of copper sulphate in thefield, or steeping the seed in a weak solution of that salt, producedconsiderable increases in the yield of barley.72A. Saeger 73 has produced further evidence to that advanced lastyear by Clark and Roller 74 to show that certain lower plants can besatisfactorily grown for many months on end in a solution of purelyinorganic salts.Although evidence was obtained for a stimulationof growth by yeast extract or peat extract,75 the necessity of organicaccessory foods (auximones) for the growth of green plants cannotbe regarded as having been proved.The Eflect of Drying the Soil.A. N. Lebediantzev 76 has carried out a comprehensive series ofexperiments on the effect on its fertility of air-drying the soil. Ithas long been known that considerable increase in fertility couldresult from this treatment. This author's results showed that as anaverage of 91 pot experiments, a 45% increase in yield of millet wasobtained by air-drying a tsernosem soil. The greatest effect was'1 St. Konsuloff, Z. Pfianz. Dung., 1925, 4B, 84; H. Lundergardh, Biol.Zentr., 1924, 44, 465; Chem. Zentr., 1925, I, 2590; T.Bokorny, 2. PfEanz.Dung., 1925, 4A, 178; A., i, 489; W. Riede, ibid., 1924, 3B, 533.72 Densch, Landw. Jahrb., 1924, 60, 139; A . , 1925, i, 766; A. Densch andHunnius, Z. Pflanx. Dung., 1924, 3A, 369; A., 1925, i, 489.7 3 J. Gen. Physiol., 1925, 7, 517; A., i, $55.7 4 Ann. Reports, 1924, 21, 196.7 5 See also F. A. Mockeridge, Ani2. Bot., 1924, 38, 723; A., 1925, i, 106.76 Soil Sci., 1924, 18, 419212 ANNUAL REPORTS ON TEE PROGRESS OF CHEMISTRY.obtained by repeated drying and rewetting. Chemical analysis showedthat there was a marked increase in soluble nitrogen and phosphatecontent consequent on drying. It is suggested that the effect isakin to partial sterilisation and that the drying of the surface layersof the soil in the field by climatic influences plays a fundamentalr6Ze in determining its fertility.Plant Biochemistry.The Nitrogen Compounds of Plants.An exhaustive study of the nitrogen compounds occurring in therye plant at different stages of ripeness has been made by A.Kie~el.'~The most noteworthy feature is the high concentration of asparticacid during the early stages. Asparagine was not found a t anyst'age, and hence it is concluded that aspartic acid is not a fore-runner of asparagine. A further study of the proteins of rye maysupply the reason for the high content of aspartic acidIt appears that fungi bear a closer resemblance to animals than tohigher plants with regard to the intermediate form in which theirnitrogen occurs, since there is evidence that the urea of fungi seemsto be the analogue of asparagine in the higher plants, behaving as awaste product in the absence of carbohydrates but as a source ofnitrogen for the building up of protein in their presen~e.~sVickery has published further papers in which is recorded theisolation of a considerable variety of nitrogen compounds fron thejuice of the lucerne plant.79Jodidi has demonstrated the presence of amino-acids and poly-peptides in the ungerminated seeds of several cereals.S0Inulin.H. Colin has shown that the formation of inulin from hexoses inthe Jerusalem artichoke occurs mainly in the pith and woody cellsof the stem.S1 In other plants, however, such as chicory, thesynthesis is confined to the roots.*2 Enzymes are not thought toplay any part in the condensation of sugars to the state of laxm-losans, and the mechanism of the transformation is unknown.7 7 2.physiol. Chem., 1924, 136, 61.78 D. Prianischnikov, Biochem. Z., 1924, 150, 407; A., 1925, i, 213; N. N.Ivanov, ibid., 1924, 154, 376, 391; A., 1925, 341, 344.79 H. B. Vickery and C. S. Leavenworth, J . Biol. Chem., 1925, 63, 579;A,, i, 873; H. B. Vickery, ibid., 1925, 65, 81; A., i, 1370; H. B. Vickery andC. G. Vinson, ibid., p. 91 ; A., i, 1370; H. B. Vickery, ibid., p. 657.80 S. L. Jodidi, J . Agric. Res., 1925, 30, 587; A., i, 1027; S. L. Jodidi andJ. G. Wangler, &id., p. 989; A., i, 1224.81 Compt. rend., 1924, 179, 1186; A., i, 620.82 Idem, Bull. SOC. Chim. biol., 1925, 7, 173; A., i, 618BIOCHEMISTRY.213Pectin.According to F. W. Norris and S. B. S~hryver,*~ pectinogen,which is converted into pectic acid by the action of lime-water,occurs in the plant as a methylated pectic acid in loose combinationwith metallic ions such as calcium, with one of its four carboxylgroups unmethylated. M. H. Carre S4 contests Tutin's assertionthat " protopectin '' does not exist, and considers that it occurs inapple tissue, being converted into soluble pectin by hydrolysis. Apectic substance has been obtained from beech-wood by M. H.O'Dwyer.85 Tutin has shown that the leaves of apples affected with" silver leaf " disease are deficient in pectin in comparison withhealthy leaves.86 A study of the pectin of the peel of citrous fruitshas been made by H.D. Poore.8'Plant Phosphatides.V. Grafe and V. Horvat 88 have isolated from the juice of thesugar beet a water-soluble phosphatide giving oleic and palmiticacids, choline and glycerophosphoric acid on hydrolysis, and withN : P ratio of 1 : 2. From a study of the phosphatides of the soyabean, P. A. Levene and I. P. Rolf 89 find that the lecithin of thisplant contains less saturated fatty acids than animal lecithin;it contains, in addition to palmitic and stearic acids, oleic, lholic,and linolenic acids, and also possibly hydroxy-fatty acids. Thecephalin of soya beans, however, did not differ appreciably from theanimal product.The Absorption of Ions by Plants.D. R. Hoagland and A. R. Davis 90 have published an interestingpaper, summarising the results obtained in the laboratory of PlantNutrition of the University of California in a series of investigationson the absorption of ions from dilute solutions resembling soilsolutions, and discussing some of the problems arising out of thiswork.The interesting results obtained in the study of the fresh-water alga Nitella, already discussed in an earlier Report?l afford astriking i!liistration of the diffusion of ions from a, solution of lowconcentration to one of higher concentration. If the second law ofthermodynamics applies in such cases, this diffusion against theconcentration gradient can come about only by virtue of work donewithin the plant cell. In conformity with this, it was found that83 Biochem. J., 1925, 19, 676; A., i, 1226.8 5 Ibid., p.694; A., i, 1225. 8G Ibid., p. 414; A., i, 1028.U . S . Dept. Agric. Bull., 1323, pp. 1-19; A., i, 619.8 8 Biochem. Z., 1925, 159, 449; A . , i, 1522.J. Biol. Chem., 1925, 62, 759; 65, 545; A., i, 487, 1520.so New Phytologwt, 1925, 24, 99.84 Ibid., p. 257; A., i, 758.Ann. Reports, 1923, 20, 225214 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.there is a definite correlation between absorption of ions and degreeof illumination, and it seems probable that energy derived fromsunlight is indirectly involved in the absorption processes. Energyrequired by root cells for these purposes would, of course, be derivedfrom carbohydrates synthesised in the green parts of the plant.The above phenomenon only obtains so long as the living cell isuninjured.These living plant cells thus appear to possess the property ofone-way permeability.It is impossible to obtain uncontaminated cell sap from higherplants, but the observations that have been made on expressedjuices are indicative of a condition which is quite analogous in severalrespects to that which exists in Nitella.The total ion concentrationof the tissue fluids of the roots of barley, and still more of the stemand leaves, is much greater than that of the solution in which thebarley is grown.Many erroneous ideas have been held regarding the selectiveaction of plants. It is certainly not true that a plant necessarilyselects from a solution only, or even chiefly, those ions indispens-able to its growth.Many unessential ions may be absorbed veryreadily ; chlorine, although unessential, is absorbed much morereadily than sulphate, which is essential. The same may applyto sodium in comparison with calcium. Although the absorptionof the two oppositely charged ions of a salt is often far from equal,this occurs mainly as an ionic exchange, not by large alterations inhydrogen-ion concentrations which are necessarily self -limited.Thus when any considerable excess of potassium ion is removed froma solution of a single potassium salt, other kations such as calciumand magnesium appear in the solution.However, one ion may markedly affect the absorption of anotherion, whether of opposite sign, as evidenced by the much slower up-take of potassium from potassium sulphate than from the chloride,or of the same sign, as when tlhe absorption of calcium or potassiumis retarded by the presence of sodium, or when the absorption ofnitrate ions is hindered by the presence of chlorine ions.The relation of ion absorption to transport of water is also ofgreat interest.Water may be absorbed either more or less rapidlythan the ions present in the solution. An adequate supply ofphosphate may be obtained from a solution of very low phosphate-ion concentration without a proportionate absorption of water.In the words of the authors, ‘‘ It is equally incorrect to consider theplant either as an organism carefully selecting only the essentialions from a culture medium or as a sort of wick, taking up thesolution, evaporating the water, and leaving the solutes behind.BIOCHEMISTBY.215There is evidence that the reaction of the medium may have animportant effect on the absorption of ions.There are many instances to show that anions may be more readilyabsorbed from an acid solution and kations from an alkaline one.The reaction of the medium, however, may have very little effecton that of the cell sap of the plant.It has been shown that equally good growth of plants can beobtained from many culture solutions of widely varying composition.Not only is the plant not dependent on a culture solution of narrowlyrestricted ionic proportions, but also wide variations are permissiblein the concentration.Since the composition of the medium is one of the primary con-siderations involved in determining the composition of the plant,it is evident that the latter, in the case of ordinary soil experiments,cannot be used as a means of deciding whether a given species has acharacteristic composition.This can only be determined by thecomparison of different plants grown under the same conditions in thesame culture solution; scarcely any data of this sort are available.Among the many problems arising out of a consideration ofthe absorption and utilisation of ions by plants, special attentionis directed to such questions as the influence of potassiumon the transformations of the organic constituents ; the relativeparts played by different ions in the buffer system of the plant ; theimportance of ion-protein relations in the plant cell.Other recent papers on the absorption of ions by plants are notedbe10w.92Biochemistry of A ni ma1 s.Fat -soluble Vitamins.In last year’s Report the author made brief reference to theinfluence of ultra-violet radiation on calcium metabolism, but inview of the apparently widely conflicting statements that had thenbeen made in va,rious quarters it was, a t the time, considered thewiser course to defer further discussion of the matter until morelight had been thrown on the nature of the changes concerned.Last year much of the needed information was supplied, so thatthe subject now seems to be suitable for review.It will be recalled that in two directions there seemed to be aconnexion between ultra-violet radiations and the vitamins.Ina2 J. G. Wood, Austral. J . Exp. Biol. Med. Sci., 1925, 2, 45; A., i, 1024;G. Andr6 and E. Dsmoussy, Coitipt. rend., 1925, 180, 1052; A., i, 758; H.LundsgSrdh niid V. l’dorbvek, Biochena. Z., 1924, 151, 296; A., i, 214;E. S. Dowding, A m . Bot., 1925, 39, 459; A., i, 871216 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the fist place, the original observations of H~ldchinsky,~~ followedby the work of Hess 94 and the extensive researches of Miss Chickand her colleagues in had proved conclusively that ricketscould be cured as effectively by exposure to the short-wave radiationsof the quartz mercury-vapour lamp as by the administration ofanti-rachitic foods, e.g., cod liver oil, whilst, secondly, stimulationof growth in animals deprived of vitamin-A had been observed tofollow exposure to the radiation~.~6The natural tendency at first was to believe that the radiationshad brought about a synthesis of the active substances in thetissues of the exposed animals, but this belief was disturbed bythe claim of Hume and Henderson Smithg7 that a resumptionof growth of animals fed on the deficient diets could be.broughtabdut merely by placing them in vessels containing air thathad previously been exposed to the rays. For a time Websterand Hill’s 98 failure to confirm these experimental results was noless confusing than the announcement by Steenbock and Blackg9that food deficient in the fat-soluble vitamins may have growth-promoting and calcifying properties conferred on it by exposureto ultra-violet light.showed that the effect noted by Hume andSmith could not be attributed to ionisation of the air, but the firstclue to the cause of the discrepancy between the results of the latterinvestigations and those of Webster and Hill was provided by thedemonstration that the growth-promoting and anti-rachitic proper-ties of the contents of vessels irradiated prior to occupancy by theanimals resided not in the air but in the sawdust employed forbedding, which the animals ate.2Similar conclusions were reached by Nelson and Steenbock aftermaking an exhaustive investigation of the problem.s Confirmationthat foods deficient in the growth-promoting vitamin-A and theanti-rachitic vitamin-D were, after exposure to the short wave-length light of the quartz mercury-vapour lamp or carbon arc,capable of restoring growth and curing rickets was soon forth-coming.Chick and Tazelaar93 Deutsch.Med. Woch., 1919, 45, 712.9i Proc. SOC. .Expo. Biol. Med., 1921, 18, 298.95 Medical Research Council, Report NO. 77, 1923.96 Hume, Lancet, 1923, ii, 1318.98 Ibid., 1924, 18, 340; A,, 1924, i, $89.S9 J . Biol. Chem., 1924, 61, 405; A., 1924, i, 1272.1 Biochem. J., 1924, 18, 1346; A., 1925, i, 211.3 J . Biol. Chem., 1925, 62, 575.O 7 Biochem. J . , 1923, 17, 364.Hume and Smith, ibid., p. 1334; A,, 1925, i, 211.Hess and Weinstock, ibid., 1924, 62, 301; 1925, 63, 297; A., 1925, i.212, 750BIOCHEMISTRY. 217The next step was to discover how the ‘‘ activated ” foodstuffsexerted their physiological action.According to one theory the treated materials emitted secondaryradiations that exerted the curative action; a view that was to alarge extent based on the claim by Kugelmass and McQuarrie thatanti-rachitic substances such as cod liver oil emit a radiationcapable of (( fogging ” a photographic plate after passing throughquartz.5 Drummond and Webster showed that the experimentson which this view was based were faulty,G and shortly afterwardsKugelmass and McQuarrie admitted their error.’According to a more attractive hypothesis, physiologically activesubstances are produced from inactive precursors in the foods byphotochemical action of the radiations.Evidence in support ofthis view has gradually been forthcoming, and its unfolding con-stitutes one of the most remarkable series of events in modernbiochemistry.The precursor of the active substances found infoodstuffs on exposure to ultra-violet light was fnst traced to theoils and fats present, and finally identified with the sterols phytosteroland ch~lesterol.~~ 9, lo, l1According to Hess and Weinstock, irradiation of cholesterol a tfirst increases the amount of light transmitted, but this effect isreversed on prolonged treatment, and they trace a parallel changein the anti-rachitic potency. Cholesterol and phytosterol undergomarked chemical changes on exposure to ultra-violet light, beingconverted into pale yellow, waxy products with melting pointsgreatly below those of the original materials.These changes areprobably of the same nature as those noted by Schulze and Winter-stein l2 in sterols which had been exposed to daylight for longperiods, or those caused by X-rays.13 Rosenheim and Webster l4have shown that the anti-rachitic factor is formed both in presenceand in absence of oxygen. Dihydrocholesterol and dihydrophyto-sterol are not endowed with anti-rachitic potency by treatmentwith ultra-violet light. The nature of the physiologically activesubstance (or substances) produced from cholesterol and phyto-sterol is as yet unknown, but the fact that it can be so readilyprepared from these well-known compounds, obtainable in aScience, 1924, 60, 272.6 Nature, 1925, 115, 837; A., ii, 630.8 Hess, Weinstock, and Helman, J .Biol. Chem., 1925,63, 305; A., i, 750.Hess and Weinstock, ibid., 1925, 61, 181, 193; A., i, 1020.10 Stecnbock and Black, ibid., p. 263.11 Drummond, Rosenheim, and Coward, J. XOC. Chem. Ind., 1925, 44,l2 2. physioE. Chem., 1904, 43, 316; 1906, 48, 546.l3 Roffo, Compt. rend., 1924, 180, 228; A., 1925, i, 293.l4 Lanwt, 1925, i, 1025.Science, 1925, 62, 87.1 2 3 ~ ; A., i, 617218 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.reasonably pure state, encourages the belief that its identity willnot remain long undisclosed.The fist clear proof has been given that the animal organism(rat) possesses the power of synthesising ~ch~lesterol.~~ A con-siderable amount of work had been presented from time to timeindicating that cholesterol is synthesised in the bodies of man andanimals, e.g., the recent studies of Gardner and Fox l6 on infants,but Channon's carefully controlled experiments decide the matteronce and for all.The elucidation of the action of ultra-violet radiations on chole-sterol and closely related sterols has progressed so far that it isevident that it is the anti-rachitic factor (vitamin-D), and not thegrowth-promoting, anti-xerophthalmia vitamin-A that is pro-duced.l* Nevertheless, as an outcome of studies on irradiated food,it has been ascertained that the administration of the anti-rachiticvitamin-D can, under certain conditions, induce growth in animalsdeprived of the fat-soluble vitamins.17, l 8 These facts have neces-sitated a revision of the methods employed for the testing ofmaterials for the presence of vitamin-A by feeding experiments onanimals.The new methods not only render obsolete processeswhich take no regard of the disturbing effects which vitamin-Dmay produce, such, for example, as those recently described byJavillier, Baude, and LBvy-Lajeune~se,~~ and by Sherman andMunsell,*O or that suggested in the recently issued 7th edition ofthe American Pharmacopeia, as the method of assay of the growth-promoting potency of cod-liver oil, but also make it clear that aconsiderable proportion of the work carried out with the oldertechnique will have to be repeated by more trustworthy methods.Sources of error such as these characterise many biologicalmethods of assay, and serve to direct attention to the pressingneed for more accurate and, if possible, more rapid processes.Theclaim by Drumrnond and Watson 21 that the long-known colourreaction which cod-liver oils give with sulphuric acid can be takenas an approximate measure of their vitamin potency has not beenchallenged, although it has not, as yet, received very much atten-tion.22323 Unfortunately, the transient nature of the reaction15 Channon, Biochem. J., 1925, 19, 424; A., i, 1001.16 Proc. Roy. Soc., 1925, 98, B, 76.1 7 Steenbock, Nelson, and Black, J. Biol. Chem., 1924, 62, 275; A., 1925, i.107.Drummond, Coward, and Handy, Biochem. J . , 1925, 19, 1068.ID Bull. Soc. Chim. biol., 1925, '4, 831; A., i, 1364.2o J . Amer. Chem. SOC., 1925, 47, 1639; A., i, 1018.21 Analyst, 1922, 4'4, 341.22 Poulsson and Woidemann, Tids.Kemi Berpmesen, 1923, 3, 169.2s Sjijirslev, J . Biol. Chern., 1924, 62, 48BIOCHEMISTRY. 2 19renders it useless for the quantitative comparison of different oils,and attempts to stabilise the colour have been unsuccessful. Rosen-heim and Drummond24 have ascertained that a variety of otherreagents produce colours similar in character to that produced bystrong sulphuric acid, and that their intensities are in a strikingmanner proportional to the vitamin-A potency as determined byfeeding experiments on animals. Of the reagents giving colours,the most satisfactory are arsenic trichloride, trichloroacetic acid,and methyl sulphate, and their superiority over sulphuric acid restson the greater permanence of the colours produced.It was foundpossible to use the reactions as approximate colorimetric methodsof assay of vitamin-A with an accuracy at least of the same orderas that of the tedious animal tests. The value of these methods aswell as that of the colour reactions proposed by Bezssonov 25 as ameans of distinguishing the anti-rachitic vitamin from vitamin-Ais still under consideration.A group of Japanese investigators has announced the isolation ofvitamin-A in the pure condition 26 by the distillation of the unsaponi-fiable matter of cod-liver oil in a high vacuum, after completeremoval of cholesterol. The product, for which they propose thename “ biosterin,” corresponds with the formula C2,H42( OH),, andthe presence of one primary alcohol group and three double bondshas been established.Careful perusal of the details of their inves-tigation, however, leaves the impression that their method ofseparation could not be expected to yield a pure product, and alarge proportion of the analytical data for the derivatives, themajority of which were heavy oils, is of questionable value. Manycriticisms of the work of Takahashi and his colleagues are containedin a recent paper by Drummond, Chanizon, and Coward,27 in whichare also described their own attempts to isolate the active substance.Fractions of the same order of physiological activity as thoseobtained by Takahashi were frequently prepared, but were foundto be mixtures. Negative evidence was obtained regarding theidentity of vitamin-A, in that the following substances, all of whichhave a t one time or another been detected as constituents ofunsaponifiable fractions showing physiological activity, were foundto be without growth-promoting activity : cholesterol, spinacene(squalene) , oleyl alcohol, phytol, batyl alcohol, and selachyl alcohol.A large proportion of the active fractions appears to consist ofunsaturated alcohols, so that it is not unreasonable to suppose thatvitamin-A may be such a substance.2d Biochem. J., 1925, 19, 751.2s Compt.rend., 1924, 179, 572; A., 1925, i, 107.26 Takahashi, Makamiya, Kawakami, and Kitasato, Sci. Papers Inst. Phy8.Chem. Res. Tokyo, 1925, 3, 81; A., i, 1365.27 Biochem. J., 1925, 19, 1047220 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.A substance bearing some similarity to vitamins-A and -D asregards what is known of its chemical behaviour is one now generallyreferred to as vitamin-E.This dietary essential was first describedby Evans and Bishop,28 who found that rats would grow to maturityon a diet containing vitamins-A, -B, and -D, but would not repro-duce. Supplementing the diet with certain foodstuffs, e.g., wheatoil, cured the condition. Confirmation of the existence of thenewly-discovered factor has been forfh~oming,~~~ 31 and recentlyEvans and Burr have provided information concerning its nature.32It was found to be stable towards light, heat, acids, alkalis, oxidationand hydrogenation, and it could be concentrated in the unsaponi-fiable portion of wheat oil without loss.Removal of the cholesterolfrom this material and distillation of the residue in a, high vacuumyielded a fraction of very high physiological activity. Furtherinvestigation of this remarkable substance will be awaited withgreat interest. Meanwhile, it is curious to note how the focus ofattention on fats has shifted from the biochemistry of the glyceridesto the study of the long-neglected constituents of the unsaponifiablefraction.a4Funk’s suggestion to subdivide them into two groups, ( a ) vitaminsand (b) vitasterols, more or less corresponding to the present termswater-soluble (B and C ) and fat-soluble ( A , D and B), seems not onlyunnecessary but unwise, since it is based on the opinions that theformer contain nitrogen and that the latter are sterols.There isno trustworthy evidence that either view is correct, and one isentitled to doubt whether the time is yet ripe for a reconsiderationof the nomenclature of these substances.With regard to recent proposals for reclassifying theChemistry of Internal Secretions.Parathyroid.-Perhaps the most striking advance that has beenmade during the past twelve months in the field of research on theinternal secretions is the preparation by Collip from parathyroidglands of extracts showing marked physiological activity of thecharacter associated with the gland itself. In last year’s Reportthe author devoted space to the subject of parathyroid tetany, andpointed out that the modern tendency favours the theory that thiscondition is directly a result of disturbances of the concentration or28 Science, 1922, 56, 650.30 Mattil and Carman, J .Biol. Chem., 1924, 61, 729.31 Sure, ibid., 1924, 62, 371; A., 1925, i, 212.32 Proc. Nat. A c d . rSci., 1925, 11, 334; A., i, 1022.33 Funk, Bull. SOC. Chim. biol., 1926, 7, 1017.34 Randoin and Simonnet, ibid., p. 1020.Amer. J . Physiol., 1923, 63, 396BIOCHEMISTRY. 221condition of calcium in the blood rather than Paton's view that itis due to the toxic action of guanidines. This tendency will begreatly strengthened by the new work. Collip, Clark, and Scott 359 36extracted fresh ox-glands with 5% hydrochloric acid at 100" for1 hour, and removed fat and the bulk of protein matter by simplemeans.Oral, subcutaneous, or intravenous administration of theextract prevented the onset of tetany in dogs from which the para-thyroid glands had been removed, or cured the condition if it hadappeared. The immediate effect of the administration was to causea rise in the concentration of calcium in the blood, and the reliefof tetany or its prevention was associated with this rise. Theinfluence of the parathyroid extract on the level of blood calciumwas most remarkable, for it was found possible by raising the doseof the active principle to bring about a condition of " hypercal-czemia," even to the extent of causing collapse and death when thenormal concentration of calcium in the blood had been more thandoubled.The condition of " hypercalcBmia " is associated with a, curiousincrease in the viscosity of the blood.Further experiments with amore carefully purificd preparation of the hormone extracted fromthe glands indicated that whilst prolonged overdosage was invariablyfatal, a single massive dose was relatively harmless.37 The changesin concentration of calcium in the blood can be made the basis ofa method of assay of the potency of the extracts.It was found possible t o produce tetany by injection of guanidineinto dogs in which the calcium concentration of the blood had beenraised by administration of the hormone; a result which seemsclearly to dissociate guanidine tetany from that related to para-thyroid deficiency, and to disprove the idea of an antagonismbetween the two agents.An improved method of preparation of theactive principle has been de~cribed.~8 Preparations in O.1N-hydro-chloric acid retained their activity after keeping for 16 months inthe ice-chest.Thyroid-Indirect light is shed on the nature of the activeprinciple of the thyroid gland, thyroxin, by the interesting synthesisrecently carried out by H a r i n g t ~ n . ~ ~ It will be recalled thatKendall believed thyroxin to be a molecule containing the4 : 5 : 6-tri-iodo-2 : 4 : 5 : 6-tetrahydroindole nucleus. The evidencein favour of this view was slender, and no answer has yet been36 Nature, 1925, 115, 761.36 J . Biol. Chern., 1925, 63, 395, 439; A., i, 754.37 Collip and Clark, ibid., 1925, 64, 485; A., i, 1017.3* Hjort, Robison, and Tendick, ibid., 1925, 65, 117; A., i, 1364.3@ Ibid., 1926, 64, 29222 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.forthcoming to many calls for details of the synthesis of thyroxinwhich it was claimed had been effected by Kendall's colleague,O~terberg.~~ Harington considered that the properties of thesubstance described by Kendall would be more satisfactorilyaccounted for if the substance were a phenyl derivative of glutamicacid. Accordingly he attempted, and achieved, the difficult taskof synthesising 3' : 4' : 5-tri-iodophenylpyrrolidonecarboxylic acid,a substance having practically the same empirical formula as thatgiven for thyroxin by Kendall, which shows certain chemicalsimilarities to the latter substance.The synthetic product wasfound to be without the effect on the basal metabolic rate which ischaracteristic of the thyroid principle.The investigation of Hicks 41 on the ultra-violet absorptionspectra of thyroxin and tryptophan indicate that an indole nucleusmight be present in the former substance.Kendall regards 2-hydroxyindole-3-p-propionic acid as theprecursor of the active principle and has published his views on itsr6Ze as a catalyst of intravital oxidations."JOvarian Hormone.-Since Adler 43 first succeeded in producingartificial estrus in animals by the injection of aqueous extracts ofwhole ovaries, a number of methods for the preparation of activeextracts have been described.Of these the most important seemsto be that of Hermann and Fra1ike1,4~ who protected their processby patent rights.The alcoholic extract of ovaries, after removalof the solvent, was treated with ether and acetone to remove certainlipoid constituents; the bulk of the cholesterol was then removedby fractional crystallisation. The active material could, it wasstated, be further concentrated by distillation at 190" under lowpressures.General confirmation of many of the observations of Hermannand Frankel, which formerly received curiously little attention,has recently been provided by the work of Allen and Doisy 4 5 ~ 4 6and of Dickens, Dodds, and Wright.47 The latter investigatorshave prepared a highly active material in the form of a clear, lightbrown oil, soluble in the chief fat-solvents. Its activity is unaffectedby the removal of cholesterol or by heating to 200°, but seems tobe lessened by treatment with alcoholic sodium hydroxide.Bymeans of a series of injections an ovariectomised rat was kept in a40 Ann. Reports, 1919, 1920, 1923. 41 J., 1925, 127, 771.42 Proc. Soc. Exp. Biol. Med., 1925, 22, 307.43 Arch. Gynak, 1912, 95, 349. 44 Eng. Pats. 113, 3111 of 1915.45 J . Amer. N e d . ASSOC., 1923, 81, 819.46 Doisy, Ralls, Allen, and Johnston, J . Biol. Chern., 1923, 59, xliii; 1924,47 Biochem. J., 1926, 19, 851,61, 711BIOCHEMISTRY 4 223state of continuous cestrus for a period of 14 days. The productionof the hormone is believed to be localised in the ovarian follicle.48Insulin and Carbohydrate Metabolism.The rate of growth of the literature dealing with insulin and itsaction is truly alarming, and each year renders the task of selectinga few papers for review more formidable.The chemical nature of the active component of commercialinsulin preparations has been studied by Abel and Geili~ig,~~ whoconfirm the generally-accepted view that such materials are verycomplex mixtures.Neglecting inorganic constituents, the Americaninvestigators were able to separate the hormone from a number ofcrystalline amino-acids and a variety of protein-like fractions. Inthe course of these processes the rabbit unit was raised from 8 or12 to more than 40. Some evidence was obtained that the physio-logical potency is related to a form of labile sulphur in the product,and the authors are inclined to believe that this is an integral partof the insulin molecule.Phosphorus is not present. Their resultsare of great interest, but the evidence €or their views regarding theassociation between physiological potency and the presence of labilesulphur is somewhat inadequate.Burn and Dale 50 have studied the localisation of the action ofinsulin by observations on the decapitated and eviscerated cat.Such a preparation, in which a supply of sugar was provided bysteady infusion of dextrose, showed the typical fall of blood-sugarlevel on injection of the hormone. Since the skin took no part inthis, it must be attributed to the heart, lungs, and particularly themuscles. Confirmation of the increase in carbon dioxide productionfollowing insulin administration noted by previous investigatorswas obtained, and the authors also agree that the amount of theextra carbon dioxide is not sufficient to account for the sugar thatdisappears.Further evidence has been forthcoming to support the view thatinsulin plays a part in the synthesis of phosphoric esters of sugarprior to its degradati~n.~~ Brugsch and Horsters 52 think, however,that in addition to synthesis of hexosephosphates the formationof polysaccharides is effected by insulin.In another paper 53these investigators give reasons for believing that the tissues ofdepancreatised animals contain a normal amount of hexosephos-48 Allen, Amer. J . Anat., 1924, 34, 133.49 J . Phamacol., 1925, 25, 421; A., i, 1512 (abstract of earlier andpreliminary communication).J .Phy~iol., 1924, 59, 164. 51 See Ann. Reports, 1924.62 Biochem. Z., 1924, 151, 203; A., 1925, i, 208.53 Ibid., 1925, 155, 459; A,, i, 483224 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.phatase, but that the synthetic action of the enzyme which buildsup the phosphoric ester is inhibited in the absence of insulin. Someevidence is also being obtained that insulin accelerates the break-down of sugar by lower organisms. Noyes and Estill 54 findincreased production of lactic acid from sugar by Lactobacillusbulgaricus and L. acidophilus when insulin is present.Much uncertainty still prevails regarding the nature of theblood sugar, and the changes which, as some think, occur in itsmolecule under the action of insulin. Lundsgaard and Holb0llfound that when glucose solution was incubated at body temperaturewith finely divided muscle tissue the optical rotatory power andreducing values agreed.If insulin was present, the former dimin-ished.55g56 These results, as well as others they have recentlyrep~rted,~' confirm in many essentials the observations of Winterand Smith.58 They could, however, be accounted for by a changein the equilibrium between a- and p-glucose, without assuming theformation of a hypothetical y-glucose.The new form of dextrose with low reducing power has beentermed by them neoglucose. Winter and Smith,59 continuing theirstudy of the nature of the blood sugar, have found that the opticalrotation of diabetic blood is considerably increased on mildhydrolysis, and that phenylosazones with crystalline forms differingfrom that of glucosazone can be prepared.Whilst it is almost certain that obscure changes do occur in theblood sugar under certain conditions in the body, it is also apparentthat small changes in the optical rotations of complex mixturessuch as protein-free blood filtrates must be exceedingly difficult tointerpret.In this connexion Holden, 6o who has identified the reduced formof glutathione as a constituent of red blood corpuscles, believes thatthe presence of this optically active substance in the protein-freeblood may be responsible for many of the effects noted by Winterand Smith and others, and offered by them as evidence of the presenceof different forms of blood carbohydrate.Visscher 61 attributestheir results to variations in the reactions of the blood filtrates.The breakdown of carbohydrates in muscle remains the subjectof considerable interest. Embden and Zimmermann 62 have now64 Proc. Nat. Acad. Sci., 1924, 10, 415; A., 1925, i, 107.65 Compt. rend. SOC. Biol., 1924, 91, 1108.66 J . Biol. Chem., 1924, 62, 453; A., 1925, i, 208.5 7 Compt. rend. SOC. Biol., 1925, 92, 387, 395, 398, 525.6a Ann. Beports, 1922, p. 195.69 Proc. Roy. SOC., 1924, 97, B, 20.61 Amer. J. PhYSd., 1924, 68, 135; A., 1925, i, 1343.6a 2. phY8iOl. Chern., 1924, 141, 225; A., 1925, i, 729.6o Biochem. J., 1925, 19, 727BIOCHEMISTRY. 225placed beyond question the identity of the hexose diphosphate(lactacidogen) of muscle with that originally isolated by Hardenand Young from the fermentation of sugar by yeast.The twosubstances gave rise to the same neutral brucine salt.Embden has somewhat disturbed the accepted views on acidproduction in muscle during contraction by his announcement thatin the first phase, in which tension is developed, twentyfold as muchphosphoric acid as lactic acid is pr0duced.6~ After a short tetanus,lactic acid, but not phosphoric, continues to be produced for a fewseconds, hence the liberation of energy due to the formation oflactic acid is not limited to the phase of shortening. The phosphoricacid liberated in the early stage of tetanus may disappear duringthe later stages, whilst lactic acid is still being formed. Theseobservations suggested to Embden that the liberation of each ofthe two acids has its own special relation to the phenomena ofcontraction; it is possible that the sudden liberation of phosphoricacid produces a single contraction, whereas lactic acid alone ismainly responsible for producing maintained contractions.Meyerhof, Lohmann, and Meier 64 haw found that pyruvic acidwas able to replace lactic acid in the resynthesis of glycogen inmuscle, whereas dihydroxyacetone, glyceraldehyde, dihydroxy-maleic acid, glycollaldehyde, and methylglyoxal were of no valuein this respect.The parallel between the modes of breakdown ofsugar by plant cells and by animal cells is also emphasised by theclear indications from the work of Neuberg and Gottschalk 65 thatacetaldehyde is normally a step in the oxidation of sugar by muscle.The aldehyde was isolated by the ‘‘ fixation ” method with calciumsulphite, and appears to be formed by the action of decarboxylaseon pyruvic acid.It has also been identified amongst the productsof respiration of higher plants.66Glutathione.The outstanding paper of the year in the field of research onbiological oxidations is one from the laboratory of Sir GowlandHopkins on glutathione with reference to its influence on the oxid-ation of fats and protein^.^' Before dealing with the contents ofthat paper in some detail, reference must be made to the successwhich has rewarded the efforts of Hopkins’s colleagues, Stewartand Tunnicliffe, to synthesise the dipeptide.68 Its constitution asa diglutamylcystine is now definitely established.Klin.Woch., 1924, 3, 1393.64 Biochem. Z., 1925, 157, 459; A., i, 727.6 5 I b d . , 1924, 151, 169. 6 G Ibid., 1925, 158, 253; 160, 256.G 7 Biochern. J., 1925, 19, 787; A., i, 1490.68 Ibid., p. 207; A., i, 795.REP.-VOL. XXIl. 226 ANNUA4L REPORTS ON THE PROGRESS OF CHEMISTRY.It will be recalled that Hopkins and Dixon showed that washedmuscle tissue that had been extracted with boiling water, washedwith alcohol, dried in a vacuum and powdered was capable of takingup considerable quantities of oxygen in the presence of gl~tathione.~~The oxygen uptake when Clarke and Lubs’s phosphate buffermedia were employed was of the order of 400 c.mm. per gramof dry powder. It has now been found that the high concentrationof phosphate in the fluid exerted an inhibitive action, and that withpreparations of the tissue component and glutathione in Ringer’sfluid the oxygen uptake might be as much as five times as great.Even higher values, 5,000 c.mm.per gram, have been recorded byMeyerhof ,‘O who used preparations of the thermostable musclecomponent and thioglycollic acid, but the conditions differed fromthose prevailing in Hopkins’s studies. The further work both ofHopkins and of Meyerhof suggested that the substance in the dried,extracted tissue which formed with glutathione, or similar substance,an oxidation-reduction system might well be one containingunsaturated fatty acids in its molecule.71 To this point Hopkinsgives attention in his recent paper.In acid solution, pH 3.04.0, the reduced form of glutathionecatalyses the oxidation of unsaturated fatty acids, probably,Hopkins thinks, by a mechanism such as Meyerhof 72 suggested :+ MO,.G-SH + o, --j. G-SH-Q M G-SHG-SH G-SH-0 --+ G-SHWhen, however, the solution is nearly neutral, or its hydrogen-ionconcentration is that of living animal tissues, the heterogeneoussystem presented by an aqueous emulsion of unsaturated fatty acidsand reduced glutathione exhibits quite another behaviour. Underthese conditions, the dipeptide is rapidly oxidised to the disulphideform, so that the system becomes inert before more than a smallproportion of the fatty acid has been oxidised. In the presence ofrelatively high concentrations of glutathione, however, it is possibleto determine that there is still a quantitative relation between theoxidation of the -SH group and that of the fatty acid, but it is notof the type that has been traced when the reacting system isdefinitely acid.In the neighbourhood of neutrality it would seemas if the reaction involving simultaneous oxidation of the yeptideand fatty acid were more of the type :G-sH-? A :I!+ MO + H,O.G-SH-0G-sH + 0, --+ G-SH69 Ann. Reports, 1922.70 Pflug. Arch., 1923, 199, 531; A., 1924, i, 118.71 dnn. Reports, 1983. 72 Pflug. Arch., 1923, 199, 531; A., 1924, i, 118BIOCHEMISTRY. 227Curiously enough, the glycerides exhibit a behaviour diff eringin certain respects from that of the free fatty acids or their sodiumsalts.Hopkins has as yet obtained no clear evidence upon whichto base an explanation of the difference, but records the interestingfact that lecithin behaves like the latter rather than the former.Meyerhof believed that the oxygen uptake of thermostable prepar-ations of washed muscle in the presence of the sulphydryl groupbecame so small after further repeated extractions to remove allfatty substances that it was negligible. This Hopkins considers tobe due to t,he hydrogen-ion concentration of the systems studied bythe German investigator. Thus, at pH 3.5 such a system exhibitedno uptake a t all, but a t pH 7.6 it absorbed oxygen to an extent neverless than that of the preparation before extraction of the fattyconstituents. It was found that the fully-extracted tissue possessesat pH 7.6 the power to reduce the disulphide form of glutathione,and this, Hopkins discovered, is brought about by the action ofprotein. It is a curious fact that muscle tissue washed exhaustivelyto remove soluble constituents still gives a strong nitroprussidereaction, which Hopkins and Dixon attributed to a “ fixed -SHgroup.” Although no absolute proof has been given that thereaction is due to this group, almost all the observed facts can beexplained on the assumption that it is.Purthermore, Hopkinshas been at some trouble to satisfy himself that the so-called‘‘ fixed -SH group ” is in reality a unit of the protein constituentsof the tissue residue. His experiments with tissue preparationsindicate that at pH 7.6 the sulphydryl group of the proteins of thethermostable muscle residue is the only reducing agent left, andprobably the only factor, even in muscle which has been simplywashed, which reduces glutathione.Szent-Gyorgyi’s assumption 73that the fixed -SH is not oxidised by the disulphide glutathione isshown to be unjustified.Conclusive evidence that the special characters of the fat-freemuscle preparations are due to their proteins is provided by experi-ments on the oxygen uptake of pure proteins in the presence ofglutathione. E’irst, it will be recalled that Heffter 74 and Arnold 75showed that whereas the proteins of blood plasma gave no nitro-prusside reaction they could be made to yield the characteristiccolour after treatment with sodium sulphite.Secondly, egg-albumin, which gives no reaction in its natural state, does so afterit has been “ denatured.” These curious facts were further examinedby Harri~,’~ who concluded that they might be accounted for by7 3 Biochem. Z . , 1925, 157, 50. 74 Mediz. Naturwiss. Arch., 1907, 1, 81.7 5 2. physwl. Chem., 1914, 70, 300.76 Proc. Roy. Soc., 1923, 94, B, 426, 441.H 228 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.assuming the existence in the molecule of a thiopeptide linkingwhich on hydrolysis or keto-enol transformation would give riseto the -SH group. Hopkins has now shown that the reaction isdue to the reduction of a group in the protein complex. No proteinwhich fails to exhibit a nitroprusside reaction shows any tendencyto reduce solutions of the disulphide, whilst a protein such asgelatin, devoid of sulphur, cannot be made to yield the nitroprussidereaction.Glutathione, in promoting the oxidation of the reduced protein,i.e., one giving the nitroprusside reaction for the -SH group, causesan oxygen uptake more or less proportional to the amount of sul-phydryl group judged to be present, but it may be as much as tentimes that which would be necessary t o oxidise the group itself.On the cessation of oxygen uptake, which occurs when the nitro-prusside reaction is no longer given, it is possible to reduce theprotein once again by treatment with reduced glutathione or thio-glycollic acid, and the newly reduced protein exhibits once againthe capacity for oxygen uptake.In this manner, it is possible alternately to oxidise and reduceprotein so that the total oxygen uptake may be as high as 10 C.C.of oxygen per gram.It would seem, therefore, that withinphysiological ranges of reaction it is the proteins of the washedmuscle tissues that are responsible for the reduction of glutathione.The process can scarcely be merely one of hydrogen transport, for,as has been stated above, the oxygen uptake may be tenfold thatrequired for oxidation of the sulphydryl group in the protein.No evidence is yet available to account for this remarkably interestingfact.A study of the influence of hydrogen-ion concentration on thesystem thermostable muscle preparation-glutathione clears up anumber of differences between the results recorded by Meyerhofand by Hopkins. At pH 3.0-4.0, fat alone is oxidised, whether thereduced or the oxidised form of the dipeptide be present.Atp , 6.0, both fat and protein are oxidised in each system, whereasa t pH 7.6 the oxidation of fat is almost completely suppressed andthat of protein is predominant. Hopkins’s concluding paragraphis worth quoting. “ I am well aware indeed that on first acquaint-ance the curious and at many points obscure phenomena describedin this paper may seem to lack biological reality. The experimentalresults . . . are yielded by systems which contain actual cellconstituents in contact with one another, and depend upon actualproperties of these constituents. Such studies would seem to bea necessary, if remote, antecedent to a fuller understanding of thebehaviour of the same constituents in the organised phenomena ofthe living cell itself.BIOCHEMISTRY.229Oxidation of Fats.The study of the oxidation of fats, to which the work of Hopkins,dealt with in the previous section, directs attention, has beenconsiderably advanced by the investigations of Clutterbuck andRaper.77 For a long time it has been taught that oxidation of thesaturated fatty acid molecules in the living body occurs a t thep-carbon atom, so that the carbon chain is progressively shortenedby losing two atoms at a time. This theory was based to a, largeextent on the well-known researches of K n o ~ p , ~ ~ in which he studiedthe fate in the animal body of the phenyl derivatives of a series offatty acids, and was strongly supported by the observations ofDakin 79 on the oxidation of the ammonium salts of the acids byhydrogen peroxide.Clutterbuck and Raper, using conditions similar to but notidentical with those of D a b , obtained products which showed thatoxidation could occur at the y- and &carbon atoms, and possiblyalso a t the ct-.So far as could be determined in the case of stearic,palmitic and myristic acids, y- and 8-oxidations seemed to takeplace to about the same extent.In 1916 Hurtley 8o published a careful study of the 4-carbon-atomacids of diabetic urine in which he came to the conclusion that thetheory of p-oxidative degradation of fatty acids in the animal bodyis inadequate. This view was supported by an experimentalinvestigation of the oxidation of butyric acid by hydrogen peroxidein which he obtained over 50% of the theoretical yield of succinicacid.8lThis fact is of particular interest, because Clutterbuck and Raper,although as yet uncertain as to the further stages in the oxidationof the 7- and 8-keto-acids yielded by oxidation of the fatty acidswith hydrogen peroxide, find that both yield succinic acid.Thismeans that the carbon chain breaks between the y- and &carbonatoms to yield the 4-carbon acid.Whether other forms of oxidation than that a t the p-carbonatom occur in the living body is not yet known, but the authorsremark on the probability that the fatty acids placed in an en-vironment with a suitable oxidation potential will be oxidised ina manner dependent on the structure of the acid rather than on themeans by which the necessary potential is obtained.Another interesting point revealed by their experiments is thatthe first step in the oxidation of the saturated acids is probably7 7 Biochem.J., 1925, 19, 384.7 8 Beitr. Chem. Physiol Path., 1904, 6 , 150.79 J . Biol. Chem., 1908, 4, 77, 221, 227, 419; A., 1908, i, 74, 119; ii, 720.*l Cahen and Hurtley, Biochem. J., 1917, 11, 164.QuaTt. J . Med., 1916, 9, 301230 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the production of a series of keto-acids and not hydroxy-acids.This is quite in accordance with the opinion expressed in 1916 byHurtley, and is also in agreement with the recent observations ofQuastel, to which reference is made on p.231. The formation ofsuccinic acid as an intermediate product of the metabolism of fattyacids in &TO and the probability that it also occurs in vivo greatlyemphasise the importance of the thermolabile system (succin-oxydone) which Batelli and Stern discovered in muscle.82 Theformer even suggests a possible path by which fatty acids mightgive rise to sugar, for succinic acid is known to be easily convertedinto fumaric and malic acids in the tissues, and the latter is con-verted into glucose in the animal exhibiting phloridzin diabetes.Bacterial Metabolism and Anaerobiosis.During the past year or two, considerable attention has beendevoted, particularly by the Cambridge school of biochemistry, tochemical changes brought about by bacterial action.Stephenson and Whetham 83 noted that in its early stages thedegradation of glucose by BaciZZus coli is almost anaerobic in charac-ter.Increasing the tension of oxygen resulted in an increase inthe absorption of the gas and also in the output of carbon dioxide,without a parallel rise in the utilisation of sugar occurring. Atthe same time, the inhibition of bacterial activity due to theaccumulation of acidic products was definitely retarded. It wasconcluded that the increased oxygen uptake indicated the break-down of some of the inhibiting acid metabolites. The breakdownof glucose under anaerobic conditions is readily effected by B. coli,but no oxidation of lactic, succinic, or acetic acid or glycerol occurs.The reason for this is a t once apparent from a consideration of theenergetics of the reactions, for whereas the breakdown of glucoseto lactic acid liberates a supply of energy for utilisation by thebacteria, as far as can be determined, all the likely paths of anaerobicmetabolism of the other substances would be endothermic reactions.This view is supported by the observation that B.coZi possessesa thermolabile system (enzyme) capable of catalysing the reductionof methylene-blue in the presence of succinates under anaerobicconditions, and by the fact that this organism grows anaerobicallywith pyruvic, lactic, succinic, or fumaric acid or glycerol as the solesource of carbon, provided nitrates are present to act as a hydrogenacceptor enabling oxidations to proceed along the path normallyfollowed under aerobic condition^.^^ The actual steps by whichthe sugar molecule is degraded are becoming clearer.After the82 Biochem. Z., 1911, 30, 172. 83 Biochem. J., 1924, 18, 498.Quastel and Whetham, ibid., 1925, 18, 519BIOCHERXISTRY. 231appearance of lactic acid, the formation of pyruvic acid has been0bserved.~5 This is, it is believed, broken down to acetaldehyde,then to acetic acid and alcohol.86 The production of acetaldehydeduring the fermentation of a large number of sugars and polyhydricalcohols by B. coZi has been proved by employing the ‘‘ side-hacking”reaction with sodium sulphite by which Neuberg demonstrated itsformation during alcoholic fermentation by yeast.87Some light is thrown on the intermediate metabolism of thecarbon chain of aliphatic acids by studies on the action of bacteriaon succinic and fumaric acids.88 Both acids are fermented byB. pyocyaneus with the production of lower fatty acids, chieflyacetic ; the fermentation being greatly accelerated by aeration.Measurements of the gaseous exchange satisfy the changes repre-sented thus :Some doubt exists, however, regarding malic acid as an inter-mediate product, because it is apparently unable to act as a hydrogendonator to methylene-blue under anaerobic conditions. 89 Thisseems to suggest that oxalacetic acid may be derived directly fromfumaric, which, if true, is not in accordance with Wieland’s theoryof dehydrogenation.Fumaric acid has been detected amongst theproducts of fermentation of malic acid, but no trace of malic acidwas found in the fermentation of fumaric acid.g0Further examination of the dehydrogenations produced bybacteria show that anaerobic growth can be correlated with theactivating powers of the organisms. Growth under anaerobic con-ditions is only possible when the bacteria possess a system capableof activating some constituent of the medium to act as a hydrogenacceptor.g1, 92, g3The widespread employment of methylene-blue as a reductionindicator in biological studies such as these has led Clark, Cohen,and Gibbs 94 to investigate the equilibrium values of the reversible8 58 0878 88990919293Quastel, Stephenson, and Whetham, Biochem.J., 1925, 19, 304.Aubel and Salabarton, Compt. rend., 1925, 180, 1183.de Graaff and le Fevre, Biochem. Z., 1925, 155, 313.Quastel, Biochem. J., 1924, 18, 363.Quastel and Whetham, ibid., p. 519.Emmerling and Reiser, Ber., 1902, 35, 700.Quastel, Biochem. J., 1924, 18, 365.Quastel and Wooldridge, ibid., 19, 652.Quastel and Stephenson, ibid., 660. g4 J . Biol, Chem., 1925, 63, liv232 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.change. It has been established that the two electrochemicalequivalents concerned in the oxidation-reduction process are asso-ciated with exactly the same energy intensity, and that the hydrogenatoms entering into the ordinary formalistic equation of reductionare associated with ionisation constants of enormous differences.This might be inconsistent with a mechanical interpretation ofWieland’s theory.It is inferred that the reduction of methylene-blue consists in the transfer of an electron pair to this oxidant,with or without the subsequent addition of one or the other ofthe components of water according to the acid-base equilibrium ofthe solution.Electrode potential measurements with suspensions of bacteriagave data agreeing with those calculated from the data for thereduction of methylene-blue. The potentials thus established bytwo methods lie in a zone where there can be no appreciable quantityof either molecular hydrogen or molecular oxygen in equilibriumwith the system. If either gas be present, it can be considered inrelation to a dynamic process only, and not to a static equilibrium.I n this connexion, Thunberg 95 has recently studied the reduction-oxidation potential of the succinic acid-fumaric acid system con-taining succino-dehydrogenase, using the values for the oxidation-reduction potential of mixtures of methylenc-blue and leuco-methylene-blue determined by Clark at different hydrogen-ionconcentrations.Another aspect of anaerobic growth of bacteria concerns thelimited tolerance of oxygen exhibited by the organisms whichnormally flourish in the absence of air.Callow 96 has pointed outthat Wieland’s theory of cell respiration holds that water is splitinto (HO) and (€I), the latter combining with the oxygen of the airto form hydrogen peroxide, which is immediately broken down bythe widely distributed enzyme catalase with production of atomicoxygen.If an organism lacked the power to decompose hydrogenperoxide, the accumulation of this substance would readily accountfor the inhibitory action which atmospheric oxygen has on anaerobes.Of nine anaerobic organisms studied, none was found to containcatalase, whilst twelve aerobic species were capable of decomposinghydrogen peroxide.Callow failed to demonstrate the presence of hydrogen peroxidein cultures of anaerobic organisms, but M’Leod and Gordon, whoseconclusions in general coincide with those of Callow, were able todoOf some bearing on the oxidation-reduction systems of bacteria95 Xkan. Arch. Php&d., 1925, 46, 339.96 J . Path.Bact., 1923, 26, 320. 97 Ibid., p. 33BIOCHEMISTRY. 233is the question whether they contain glutathione. M’Leod andGordon, who obtained positive colour tests, think the reactionswere due to the reduction by the organisms of oxidised dipeptidein the broth.98 Callow and Robinson, on the other hand, areinclined to believe that certain bacteria actually form a substancegiving the nitroprusside reaction. It is uncertain whether thissubstance is glutathione or not. It is not hydrogen s u l ~ h i d e . ~ ~Some years ago Weinland reported that the intestinal worm,Ascuris Zumbriwides, does not require oxygen for its metabolismand lives equally well in atmospheres of inert gases. To accountfor the ability to perform muscular movements under these con-ditions Weinland suggested that the energy is derived from thebreakdown of glycogen according to the equation4C,H1,-,0, + 4H20 -- 9c02 + 3C4H9*CO2H + QH,.He detected carbon dioxide and a volatile acid resembling valericacid, but was forced to assume that the hydrogen is taken up by ahydrogen -acceptor and is not liberated.Weinland satisfied himselfthat the valeric acid was not produced by contamination withbacteria, but Fischer2 has recently demonstrated that he. wasincorrect and that the only acids formed under conditions of sterilityare lactic and phosphoric acids. Slater 9 has submitted Weinland’swork to a careful re-examination, and has found that although theworms are capable of prolonged existence in the absence of air,they achieve this only hy restricting their movements.For theirmetabolism they undoubt>edly require oxygen or its equivalent.Confirmation of the view that the volatile acids are products ofbacterial contamination was also obtained by him.Enzyme Action.For a number of years past, the output of literature dealing withenzyme action has been very large, but in the opinion of the reporterthe proportion of papers that have announced results of any out-standing interest has been curiously small.Dealing with general principles, the paper by Briggs and Haldane,*in which an examination is made of the theoretical basis of theequation of Michaelis and MentenY5 applied with success by Kuhnand others to numerous cases of enzyme action,6 is a valuablecontribution.The same may be said of a series of papers from the Toronto98 Biochein.J., 1924, 18, 937. sg ibid., 1925, 19, 19.2. BWl., 1901, 42, 55; 1902, a, 86.Biochem. J . , 1925, 19, 604.Biochem. Z., 1913, 49, 333.Oppenheimer’s “ Die Fermente und ihre Wirkungen,” 1924, 185.Biochem. Z., 1924, 144, 224.Ibid., p. 338.H234 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.school of biochemistry, in which are described researches on theenzymic synthesis of proteins. As far back as 1886 Danileffskyobserved the formation of a precipitate (plastein) when stomachextract was added to a concentrated solution of the products ofpeptic hydrolysis, and drew the conclusion that synthesis of asubstance resembling a native protein had occurred. Generalconfirmation of this observation was provided by Sawjaloff andother workers,’ but the conditions under which synthesis occurshad not been at all clearly defined.Hesse obtained plasteinformation from Witte’s peptone by papain or rennet a t pH 2.8 to5.4, but not when the acidity was greater than pH 2.8. No synthesistook place when the enzymes were inactivated. Wasteneys andBorsook9 have recently found that by the action of pepsin a tp H 4.0 on a concentrated solution of the products of peptic hydrolysisof egg-albumin a precipitate is formed which contains as much as39% of the nitrogen of the original solution, and is of the order ofmolecular complexity of the original protein. Plastein is rapidlyhydrolysed by pepsin at pH 1.7, but the proteoses left in solutionafter plastein has been synthesised are not attacked by the enzyme.This points to the re-formation by pepsin of a particular linkingwhich under other conditions of dilution and acidity may be rup-tured by hydrolysis.The effect of concentration is, as the earlierwork indicated, marked. Between concentratioiis of substrate(hydrolysed products) corresponding with about 8% and 25% ofprotein, the amount of protein synthesised by pepsin at the optimumhydrion concentration, pH 4.0, increases directly with the concen-tration. Below 8% no synthesis takes place, and it is inhibitedabove 25%. Peptic hydrolysis of egg-albumin can proceed tocompletion only when the concentration of protein is 6% or less.The interesting observation is recorded that by the action of trypsina t pH 5-7 on a solution of the products of peptic hydrolysis of egg-albumin a substance was obtained having similar properties to theprotein synthesised in the experiments with pepsin.Considerable light has been thrown upon the mechanism of theaction of tyrosinase on tyrosine by a series of careful investigationsmade in the past few years in Professor Raper’s laboratory atManchester. In 1923 it was shown that the formation of melanintakes place in stages, which can be clearly distinguished.Of thesethe first appears to be an oxidative one whereby the tyrosine isconverted by the enzyme into a red pigment which is the first7 2. plbysiol. Ghem., 1907-8, 54, 119; A., 1908, i, 234.8 Arch. Verhuungekr., 1923, 31, 275.8 J .Bwl. Chern., 1924, 62, 15; 1925, 62, 633, 675; 1925, 63, 563, 575;A,, i, 102, 472, 865BIOCHEMISTRY. 235visible sign of oxidation. At pH 6.0 this product is the main pig-mented substance formed, but in less acid solutions it rapidly passesinto a colourless substance and finally into melanin.1° Of theselast two changes the former appears to be of the nature of an intra-molecular rearrangement, whilst the latter is an oxidation greatlyaccelerated by the phenolase present in the preparations oftyrosinase.In the past, almost all theories of the action of tyrosinase ontyrosine were based on the assumption that deamination of theamino-acid takes place in the first phase. Thus Bach,ll who waslargely responsible for this view, suggested that the action oftyrosinase on tyrosine was to convert it into hydroxyphenyl-acetaldehyde, ammonia, and carbon dioxide, with the intermediateformation of the corresponding keto-acid.Later, in his opinion,came a complex change in which oxidation of the aldehyde,before or after condensation with ammonia, led to the formationof melanin. This view was accepted by Onslow.12 The studiesof Raper and Wormall l3 show, however, that there areno grounds for the assumption that deamination occurs, for notonly is there no production of ammonia during the oxidation oftyrosine by tyrosinase, but the enzyme has no action on solutionsof p-hydroxyphenylpyruvic acid, either in the presence or absenceof ammonia.Happold and Raper l4 support this evidence with the observationthat there is no aldehyde formation, liberation of ammonia ordecrease in arnino-nitrogen when tyrosinase (potato) acts on glycine,alanine or phenylglycine.The formation of ammonia noted byChodat and Schweizer l5 when tyrosinase acted upon amino-acidswas due to the p-cresol that was added as a component of thereacting system. The same action is shown by phenol and catechol,but not by resorcinol, quinol or p-benzoquinone. Much the sameconclusions were reached by Robinson and McCance.16 It issuggested by Happold and Raper that cehain phenols in $hepresence of amino-acids form intermediate o-quinone derivativeswhich attack the amino-acids with liberation of ammonia. Thenecessity of an amino-group for melanin formation is also apparentfrom the studies of Gortner,17 who found that whereas both tyrosineand p-hydroxyphenylethyl alcohol are oxidised by tyrosinase to a,lo Biochem.J., 1923, 17, 454.Biochem. Z . , 1914, 60, 221; A., 1914, i, 445.l2 Biochem. J., 1923, 1'7, 216.l3 Ibid., 1925, 19, 84; A., i, 473. l4 Ibid., p. 92; A., i, 474.l 5 Arch. Sci. Phye. Nat., 1913, 35, 140. l6 Biochem. J., 1925, 19, 251.Proc. SOC. Exp. Biol. Med., 1924, 21, 543: A., 1925, i, 474.H* 236 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.red pigment, only in the former case does the oxidation proceed tothe formation of black pigments.These new observations on the action of tyrosinase are closelyrelated to those recorded by Onslow and Robinson,18 who find thatan enzyme preparation from the potato tuber oxidises tyrosol,y-cresol or phenol to dihydroxy-derivatives which give rise toperoxides.3 : 4-Dihydroxyphenylalanine, for some time past regarded as aprobable early stage in the oxidation of tyrosine in vivo, is oxidisedby the potato enzyme to a red pigment, which in turn becomes ablack melanin.Onslow and Robinson think that the 3 : 4-di-hydroxyphenylalanine suffers oxidative deamination with formationof 3 : 4-dihydroxyphenylacetaldehyde and ammonia, which latertake part in the formation of melanin. As we have seen, the workof Raper and his colleagues throws doubt on this theory.Plant and Animal Nucleic Acids.Observations that may seriously disturb accepted views regardingthe relation between the nucleic acids from plant and from animalsources are reported from the laboratory of Walter Jones.It will be recalled that the former acids were considered to beclearly differentiated from the latter by their containing uracilinstead of thymine as one of the two pyrimidine bases in themolecule, and a pentose instead of a hexose sugar.It has, however,long been known that two substances, inosinic acid and guanylicacid, closely related in structure to the units of plant nucleic acids,can be isolated from animal tissue. Formerly it was somewhatgenerally assumed that they were derived from plant foods eatenby the animal; an explanation that had always seemed uncon-vincing. In 1923, Jackson 19 demonstrated the presence of anadenine nucleotide in blood, and Jones and Perkins 2o have nowreported that the p-nucleoprotein of the pancreas yields not onlyguanine nucleotide, but also adenine and cytosine nucleotides, inspite of the assumption made by certain experimenters that noadenine is present. The crystalline form, chemical composition,and properties of the isolated nucleotides correspond with thoseisolated from yeast nucleic acid.I n a more recent paper,21 it isshown that by treating yeast nucleic acid with dilute sodiumhydroxide a t room temperature it was decomposed into its con-stituent nucleotides without the separation of phosphoric acid orfree purine bases, and without deamination occurring. The nucleo-l8 Biochem. J., 1925, 19, 420.ao Ibid., 1924, 62, 291.J . Biol. Chem., 1923, 57, 121; 1924, 59, 529.2 1 Ibid., p.557BIOCHEMISTRY. 237tides of guanine, adenine, and cytosine were isolated in quantity,but no trace of the corresponding uracil compound was detected;a fact all the more remarkable because of the ease with which thisparticular nucleotide can usually be separated. The conclusion isdrawn, therefore, that the uracil derivatives hitherto described asisolated from yeast nucleic acid are secondary products arisingfrom the corresponding cytosine derivatives. It seems probable,as Jones and Perkins remark, that the distinction between animaland plant nucleic acids will in future not be so definitely drawn.Regarding the alternative structures proposed for the nucleicacids, Levene and Simms 22 have pointed out that the differenttheories require a different number of ionisable hydrogen atoms inthe nucleotide molecule. The results of a study by electrometricmethods of the dissociation constants of four nucleosides and thecorresponding nucleotides are in harmony with the structure proposedby Levene 23 in so far as they indicate that the latter compoundspossess only one (secondary phosphoric acid) group, which isdissociated at about pH 6.0, whereas the theory of Jones 24 requirestwo ionisable hydrogen atoms in this region.Additional evidencein support of Levene’s views of the structure of these compounds isprovided by the examination of the nucleosides which he has~ynthesised.~~Hemoglobin and Related Pigments.A most important series of contributions to our knowledge ofhaemoglobin has appeared from Professor Barcroft’s laboratory.It has been found 26 that the blood pigment can exist as such onlyin the neighbourhood of neutrality, for in definitely acid or alkalinesolutions it is converted into haemochromogen. The formation ofthis substance does not, as was previously believed, involve theseparation of globin from the iron-containing unit.Both haemo-chromogen and its oxide, haematin, are conjugated proteins contain-ing globin. Anson and Mirsky propose the name hcem for thenon-protein part of the molecule containing pyrrole nuclei and iron.Hem may be prepared from hmmin by reduction by sodiumhydrosulphite in alkaline solution, and it shows optical andchemical properties differing widely from those of hEmochromogen.It may, however, be converted into a substance indistinguishablefrom hemochromogen by the addition of globin. Moreover, haemmay be combined with other proteins, amino-acid or nitrogenous22 J . Biol. Chem., 1925, 65, 519; A., i, 1478.23 Ibid., 1919, 40, 415; A., 1920, i, 193.24 Amer. J . Physiol., 1920, 52, 193; A., 1920, i, 687.2 5 J . Biol. Chem., 1925, 65, 463; A., i, 1463.2 6 Anson and Mirsky, J . Physiol., 1925, 60, 50; &4., i, 1475238 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.bases of various types to yield a variety of “ haemochromogens,”all of which have similar but not identical properties. The import-ance of this discovery is far-reaching. I n the first place it revealsthe remarkable fact that haem is the iron- and pyrrole-containingunit of probably all the natural pigments of the haemoglobinKeilin’s studies28 of the widely occurring respiratory pigment cyto-chrome (formerly known as myohzmatin or histohaematin) supportthis view. The apparent universal presence of haem as a constituentpart of the respiratory pigments of plant and animal tissues rendersunnecessary the assumption, in order to explain the haphazarddistribution of haemoglobin in nature, that the capacity to synthcsisethe iron-containing unit has been developed independently manytimes. I n last year’s Report attention was directed to the indica-tions from Barcroft’s work that the nature of the protein boundto the iron-containing unit appeared profoundly to affect the gas-binding powers of the pigment. The new researches on hzm gosome way towards making clear how this occurs. Haem itself isfrom the biological standpoint an impossible gas carrier, if for noother reason than because it is practically insoluble in water. Astudy of the influence of globin on the properties of hrxzmoglobinhas been made by comparing haem, a series of htemochromogensand haemoglobins in respect to their combination with carbonmonoxide under different conditions. This study supports theconception of the blood pigment as a most highly evolved substance.a-Haemochromogen, p-haemochromogen, and hzmoglobin representsuccessive advances in the production from hzm of an ideal respir-atory pigment. Space will not permit more than brief referenceto an extremely valuable series of papers from the pen of Adair,Z9dealing with the physical chemistry of the haemoglobin system.Also of importance are the observations of Conant and Fieser30on methaemoglobin. The nature of this curious compound at lastseems reasonably clear. It appears that in the change frommethaemoglobin to hzmoglobin one hydrogen atom is involved,and that the two pigments are related one to the other as are ferricand ferrous compounds.Spermine.Careful investigations of the occurrence and nature of this veryinteresting substance have recently been recorded. Rosenheim hasmade a valuable survey of the literature on sperrnine3l and has27 Anson and Mirsky, J . Physiol., 1925, 60, 161; A., i, 1476.2 8 Proc. Roy. SOC., 1925, 98, B, 312; A., i, 1112.29 J . Biol. Chem., 1925, 63, 493, 499, 515, 517, 529; A., i, 850, 851.90 Ibid., 1925, 62, 595; A., i, 455.31 Biochem. J., 1924, 18, 1253; A., 1926, i, 180BIOCHEMISTRY. 239explained many of the conflicting opinions and statements thathave appeared. The characteristic crystals of the phosphate fromsemen were noted for the first t'ime, not by Bottcher in 1865 ashas generally been believed, but by Leeuwenhoek as far back as1678. Several new methods for the preparation of the phosphatewere worked out by Rosenheim, which led to its detection in variousanimal organs other than testes and in yeast.Wrede and Eanik 32 reinvestigated the base isolated from humansperm by K ~ n z , ~ ~ who gayc it the formula C2H,N. It -as found tobe cadaverine and not the base described as spermine by Schreinerin 1879.34 The latter substance was prepared from human semen,and found to be represented by the formula C,oH,,N4 : its propertiesand salts were examined.35 -4 fuller description of the isolation ofspermine from tissues and of its chief salts is given in a paper byDudley, Ri. C. Rosenheim, and 0. Rosenheim,36 who also adoptt,he formula CIoH26N4. It now appears highly improbable that thiscurious substance is in any way related to the internal secretionof the male reproductive organs, as was a t one time imagined,and the elucidation of its constitution will be awaited with greatinterest.J. C. DRUMMOND.H. J. PAGE.32 2. physiol. Chem., 1923, 131, 29, 38.33 A., 1888, 1122. 34 A,, 1879, 72.35 2. physiol. Chem., 1924, 138, 119.30 Biochern. J., 1924, 18, 1263; A., 1925, i, 294

ISSN:0365-6217    

DOI:10.1039/AR9252200194

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

CRYSTALLOGRAPHY.THE death in 1919 of Professor E. von Fedorov from starvation as aconsequence of the Russian revolution robbed the scientific worldof one of the most brilliant crystallographers of all time. He it waswho first proved the possibility of 230 types of crystal structure-a gigantic achievement in itself, although only one of many contri-butions to crystallography put forward by this remarkable man.Unfortunately, many of Fedorov's most interesting papers haveremained entirely or too long in the original Russian, with the resultthat during his lifetime the author never received full credit for hiswork nor crystallography the full benefit of it. A life of struggleagainst many reverses and misunderstandings ended in tragedy.The pleasure was denied him of outlliving the publication of whatmay be said to be his greatest conception, the practical expressionof all his crystallographic ideas, " Das Krystallreich." * Thepreparation for publication of this enormous work was completedby his pupils in 1920, but it is only during the last twelve monthsthat a copy has come into our hands.The object of " Das Krystallreich '' is the classification of allmeasured crystalline substances in a consistent and unambiguousmanner so that the list may afford a rapid and trustworthy means of" crystallochemical analysis." From mathematical considerationsof the space-lattices, Fedorov divides all crystals into two basictypes, cubic and hexagonal-prismatic, the former in its turn beingsub-divided into the hexahedral, octahedral, and dodecahedra1 classes,corresponding to the simple, body-centred, and face-centred cells,respectively.Furthermore, crystals of cubic type must be con-sidered as either tetragonaloidccl (the angle of the main prism lyingbetween 45" and 52$"), or trigonaloidal(521,-60°). The hexagonal-prismatic type includes all hexagonal and hexagonaloidal crystals.Fedorov then supposes that the faces with the densest distributionof corresponding points are revealed by the characteristic habit of acrystal, i.e., they predominate in a statistical investigation by reasonof their large size and frequent occurrence. Such faces he denotesby the simplest indices and the other (less important) faces by morecomplicated ones. In accordance with this way of regarding theByE.von Fedorov. VIII Series, Vol. xxxvi ofthe Proceedings of the Academy of Science of Russia.* " Das Krystallreich. Tabellen zur Krystallochemischen Analyse."Pp. Ixxiv. + 1050 + AtlasCRYSTALLOGRAPHY. 241morphology of crystals, the reader will find that for the majority ofcrystals described in “ Das Krystallreich ” the crystal-axes aredifferent from those usually adopted (in Groth’s “ ChemischeKrystallographie,” for instance). Fedorov considered that forevery crystal there is a “ correct setting ” (“ die richtige Aufstel-lung ”), which can be chosen from a study of the habit with the aid ofcertain rules enunciated by him. The characteristics of the habitare given by the “ habit symbol ” (“ das Komplexsymbol ”), in thegeneral caseN s ; & x ; Prtfbr t q .In this symbol, N = 3, 4, or 6, according as the crystal is tri-,tetra-, or hexa-gonaloidal; s denotes the class of structure (h forhexahedral, o for octahedral, and d for dodecahedral; no letter isused for the prismatic class) ; cc is the angle between the parametralplane and the basal pinakoid; 4 is the deviation of the prism anglefrom the true tetragonal, trigonal, or hexagonal angle.The anglesx, p, and + express in a similar manner the deviations of monoclinicand triclinic crystals from ideal orthogonal cells.After the “ habit-symbol ” of a substance has been derivedaccording to the rules given by Fedorov, it is an easy matter tolocate it in the tables. Accompanying it will be found a shortdescription of the substance and the literature relating to it.In thecase of symbols which are nearly the same, e.g., those of isomorphoussubstances, the author recommends that advantage should be takenof the colour, melting point, and the simpler chemical reactions.In the introduction to the tables examples of the determination ofthe various types of structure are discussed and a short history of thequestion is given. The second volume of the work (which describesand classifies some 9000 crystals) is an atlas of stereographic pro-jections of the crystals described in the first volume. Perhaps themost important feature of the work is the classification of crystals,not according to the ordinary crystal-class, but according to theirbasic structures as defined above.By this means Fedorov hassucceeded in bringing out and emphasising very many interestingrelations and resemblances between substances which were hithertoconsidered as unconnected. From the point of view of chemicalcrystallography, such an arrangement is invaluable. It is to behoped that X-ray analysts will take immediate advanta,ge of it.The Structure of Quartz.Of all the innumerable types of crystals which go to make up theFor hundreds earth’s crust, probably quartz is the most celebrated242 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of years it has excited the interest and curiosity of the layman andprofessed scientist alike. It will be recalled that it was on quartzthat Steno in 1669 established the Law of Constancy of Angle, thatquartz was quoted by Haiiy as a particularly good example of hisprinciple of “ hemihedrism,” that in quartz Arago in 1811 dis-covered the phenomenon of optical activity and Biot the law con-necting this activity with wave-length; and that through quartzalso it was first pointed out by Sir John Herschel in 1822 thatcrystals which are dextrorotatory are mirror-images of crystals whichare laworotatory.Time and again attempts have been made on theproblem of its structure, but with incomplete success even with thepowerful resources of X-ray analysis. Although it was one of theearliest crystals to be examined by the new methods, it has beenvery difficult to draw any really satisfactory conclusions aboutthe details of its structure.Recently1 the problem has beenattacked along new lines, with results which would appear to bevery near the truth, since they afford a reasonable explanation ofboth the intensities of reflexion and the physical properties of thecrystal, in particular the well-known series of twins.At 575”, ordinary (a-) quartz changes to p-quartz, the trans-formation corresponding to a symmetry change from trigonal-trapezohedral, space-group D34, to hexagonal-trapezohedal, space-group D64. The latter form, being much the simpler structure ofthe two, is more amenable to X-ray analysis and has yielded datathe interpretation of which has proved distinctly gratifying, notsimply on its own account, but because of the direct indicationswhich it gives of the structure of common (low-temperature) quartz.For all experiments point to this inference, that a-quartz i s a slightlydistorted form of p-quartz.The general features of the two latticesare remarkably alike. Disregarding the heat expansion, there islittle to choose between them except with regard to the intensitiesof reflexion of the different planes, and these intensity variations,of course, contain the key to the problem of the actual distortionrequired to produce one form from the other. The solution of thisquestion also has been attemptedY2 again with satisfactory agree-ment. A good idea of the structures now proposed for a- and 8-quartz may be obtained from Figs. 1 and 2. The larger circlesrepresent silicon atoms, the smaller ones oxygen.It will be easilyseen how one structure is derived from the other. They are bothbuilt on the basis of a threefold spiral of silicon atoms with anapproximate tetrahedral arrangement of oxygen atoms around eachsilicon atom. I n the hexagonal form, this oxygen arrangement is1 W. H. Bragg and R. E. Gibbs, PTOC. Rog. SOC., 1925, A , 109,405.2 R. E. Gibbs, &id., 1925, A , 107,561 ; 1926, A , FebFIG. 1.FIG. 2.FIQ. 3.[To face page 242.CRYSTALLOGRAPHY. 243almost exactly tetrahedral, and it is possible that it corresponds to astriving after the true tetrahedral symmetry which one might expectfor the quadrivalent silicon atoms. It will be remembered thatsilicon itself crystallises after the manner of diamond, i.e., eachatom is tetrahedrally surrounded by four others, whilst the recentlydetermined structure of P-cristobalite 2 (stable modification between1470" and 1710" examined between 290" and 430") preserves also thediamond arrangement of silicon atoms with an oxygen atom insertedbetween each pair.Thus in p-cristobalite each silicon atom issurrounded tetrahedrally by four oxygen atoms a t distances of1-541 A.U., with each oxygen exactly halfway between two silicons,but in p-quartz each silicon is surrounded by oxygen atoms nearlytetrahedrally at distances of 1-55 A.U. with the two oxygen-siliconlinkings (O\si/O) not collinear but inclined at about 155". Incommon ( a - ) quartz, it has been estimated that the two oxygenatoms lie neither in the same planes as the silicon atoms nor half-waybetween them, but rather in planes about c/9 above and below thesilicon planes.The regular tetrahedral character is lost, the oxygen-silicon linkings being now at about 147" due to a movement of thesilicon atoms of about 0.3 A.U. from their P-positions.The structure of the two forms of quartz outlined above offers avery reasonable explanation of the remarkable twinning exhibitedby a-quartz. The four well-known twins are all deduced in theoriginal paper, to which reference should be made for details. Thenature of other physical properties is also touched upon. A paperon P-quartz, giving similar experimental results and conclusions,is promised by Wyckoff .4The Crystullogruphy of Cellulose und Related Substances.It is now five years since the problem of the structure of cellulosewas first attacked by X-ray methods.Since then, thanks to thevaluable work of the Kaiser Wilhelm Institut fur Faserstoff chemie,an interesting series of experiqental results has been recordedwhich, although a final solution is still not available, purelychemical investigators cannot afford to neglect. If only for thisreason, a short review of the present situation seems desirable.For cellulose itself, the crystallo-chemical conclusions remainsubstantially the same as they were in 1921.5 The unit cell isorthorhombic or slightly monoclinic and contains the substance ofR. W. G. Wyckoff, Amer. J . Sci., 1925,9,448.Science, 1925, 62, 496.R. 0. Herzog and W. Jancke, 2.Phyeik, 1920, 3, 169; R. 0. H., W. J.,and M. P61,1Bnyi, ibid., p. 343; M. P61&nyi, Naturwiss., 1921, 9, 288; R. 0.Herzog, Cellulosechem., 1921, 2, 101 ; 1925, 6, 39; A,, i, 639244 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.four C,H,oO,-groups. The cell-edge which generally lies parallelto the fibre-axis seems to be fairly accurately determined and is thesame for the many varieties of cellulose that have been tested. Thelengths of the other two edges cannot be considered so trustworthy,for it is impossible to take rotation photographs about them, but itis very probable that the smallest group which is regularly repeatedthroughout the structure is (C6H1,0,),. This group may con-ceivably have to be multiplied by two, four, eight, or even a highernumber (although the evidence is as yet rather against such multi-plication), but odd multiples, such as three or five, of (C6H100,) areexcluded.Attempts have been made to enunciate somethingchemically more definite than this, but the discussion of these maybe left to the expert in cellulose chemistry. I n any case, there isstill much more crystallographic information required before we canfeel we are on safe ground. Most of the spots on cellulose photo-graphs are consistent with the cell proposed, but P6lAnyi hasobserved certain exceptions. Whether these are due to latticedisturbances or to the presence of another crystalline substancecannot yet be decided, but it is very likely that the latter explanationis the correct one.In the opinion of Herzog,6 the conception of cellulose as a two-phase system, an amorphous phase in which crystallites are em-bedded, helps to explain an important part of its behaviour.Inmany natural fibres, e.g., hemp and ramie, the chief axis of thecrystal cells and of the primitive fibres of the crystallites lies fairlyexactly along the fibre-axis. Microscopic investigation reveals theexistence of a primary isotropic substance in which the crystallitesare disposed. X-Rays also show the presence of a not unimportantquantity of amorphous matter, probably amorphous cellulose.Jancke has shown, from a large number of X-ray photographs ofbark fibres, that the dimensions of the crystallites in two directionsare about 112 and 66 k U . , respectively, with the third dimensionsomewhat similar.It is noteworthy that this observed crystallitesize is of the same order as that found, by diffusion experiments,for cellulose micelles, i.e., the particle size is conserved during thecrystallisation process.I n the deformation of metals by cold-working, hardening isproduced by gliding and crumpling of the glide-plane systems, butin cellulose the corresponding hardening does not seem to depend onany change in the crystallites, but rather on a flow and their moreuniform distribution in the inter-crystalline substance caused by theapplication of stress to the two-phase system. That the plasticdeformation depends substantially on this flow is evidenced by theBer., 1925, 58, [B], 1254; A., i, 1045CRYSTALLOGRAPHY.245close connexion between the stretching processes, quantities suchas the breaking-stress, and the water-content of the material tested.The greater the swelling, the more pronounced the flow; and thisfact is independent of whether or not the original material exhibitsfibre-structure. Extension brings about a very small increase inthe alignment of the crystallites, but films show no such effect onpressure or rolling.Cellulose which has been mercerised (treated under tension withstrong caustic soda solution, and subsequently washed) gives rise toa rather different X-ray diagram from that of native cellulose. Thelattice is very slightly increased, although the density remains practic-cally the same. argues from this that there is a chemicalrearrangement in the molecule (without increase of molecule size)of the crystalline constituent or constituents.The mercerisationprocess can be easily followed by means of JZ-rays, and the mechani-cal and X-ray changes do not run parallel. J. R. Katz and H. Markhave studied the swelling and mercerisation of cellulose,8 etc. Theswelling of cellulose, fibroin, and chitin in water and of cellulose(ramie) in aqueous solutions of zinc chloride, calcium thiocyanate,potassium iodide, and potassium iodide with mercuric iodide showsno lattice change, but in sufficiently strong solutions of the hydr-oxides of sodium, potassium, and lithium, or of ammoniacal copperoxide, a new X-ray diagram is produced. An enlargement up to4% may be observed.All artificial silks,9 with the exception of“ acetate-silk,” give rise to the same X-ray photograph as that ofmercerised cellulose. “ Cuprammonium-silk ” in particular, becauseof its fairly definite fibre-structure, shows this effect well.Chitin from various sources and silk-fibroin lo from nine differenttypes of silk have also been examined by X-rays. The results aresimilar to those for cellulose, that is, the crystallites are orientedwith a crystal-axis approximately parallel to the fibre-axis and areembedded in a cementing substance (“ Kittsubstanz ”) ; they possessrhombic or nearly rhombic symmetry and are based on unit cellsof the usual order of magnitude containing the substance of fourof the chemical groups given by the empirical formulagives an interesting comparison :HerzogHerzogTetraphenyl-Cellulose. Silk-fibroin.Chitin. UrBi3.cell in (A.u.)~ 680 675 ca. 1900 1965nM . . . . . . . . . . . . 653 500-660 ca. 1600 1467Naturwiss., 1924, 12, 955 et scq.Proc. K . Akad. Wetensch. Amsterdam, 1924, 27, 520; A., 1925, ii, 666;2. phy&kal. Chem., 1925,115, 385; A., ii, 660; Z . Elektrochena., 1925, 31, 105;A., i, 640; Cellulosechemie, 1925, 6, 35, 37; A., i, 639, 640.R. 0. Herzog and H. W. Gonell, Kolloid-Z., 1924, 35, 201.lo R. Brill, Annalen, 1923, 434, 204246 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The results in the last column, given for purposes of comparison,are due to Mark. The quantity nM is the product of the numberof molecules per cell and the molecular weight.If these unit cellsare correct, it certainly appears as if the respective true molecularweights are not very high multiples of the simplest empirical molecularweights.The rontgenographic comparison of plant- and animal-cellulose ' 9 l1has yielded a result of chemical interest. The animal-cellulosetunicin gives rise to a powder diagram in which the six interferencerings are identical in position and intensity distribution with therings obtainable from plant-cellulose (ramie). This observationconfirms what has been known to chemists for some time, that thesetwo celluloses are either identical or very nearly so. A photographof lichenin showed no such agreement.Growth and Deformation Structures in GerLeral.The substances briefly described above are more or less familiarexamples of that large class of crystalline structures which hasreceived the name of " growth-structures " (" Wachstumsstruk-turen ").These structures are crystal-aggregates which arecharacterised by the property of a statistical anisotropy in theirphysico-chemical behaviour. X-Rays show in the clearest possibleway that they are built up of crystallites arranged, not as in aquasi-isotropic medium with complete irregularity, but accordingto a plan in which some chief crystallographic direction coincidesmore or less exactly with an important direction in the structure.They recall a t once such typical structures as fibres, cellulose, silk,chitin, muscle, tendon, hair, electrolytic precipitates, etc.Scarcelyto be considered apart from these growth-structures is the classwhich may be described as " deformation-structures," as examplesof which may be quoted hard-drawn metal wires, rolled foils, andplastically deformed polycrystals in general. I n the realm ofgeology and among the framework and skeleton structures of biologyare numerous types of this statistical anisotropy of crystal-aggregates. The nature of a few of the most important or interestingmay here be indicated.The simplest case is the ordinary fibre structure associated withthreads of naturally grown cellulose and other fibrous substances.I n this type the crystallites are all oriented so that one of the edgesof the unit cell lies parallel to the fibre-axis, i.e., the direction offastest growth.A powder-photograph with the X-rays perpendi-cular to the fibre-axis becomes thus specialised into a rotation-photograph about the fibre-axis, and since this is a chief crystallo-11 R. 0. Herzog and H. W. Gonell, 2. physiol. Chem., 1924,141,63CRYSTALLOGRAPHY. 247graphic direction, thc spots lie on the usual series of hyperbola,(hkO), (hkl), etc. From these hyperbola the primitive translationof the crystal-lattice which lies parallel to the fibre-axis is accuratelydetermined and the other two axes are estimated more or lesscorrectly according to the degree of perfection of the photograph.A very definite example of this type is afforded by the various kindsof asbestos. For instance, in anthophyllite,12 the b-axis liesaccurately parallel to the fibre-axis and is 5-27A.U.long. Theother two axes are a = 8.7 B.U. and c = 12.40. The crystal-aggregates of benzene also constitute an important growth-structure.Here we observe without ambiguity that c = 6.S Lf.U., and, withgreat probability, that a = 7.6 B.U. and b = 9.6 A.U. In general,the direction of fastest growth in a growth-structure correspondsto the shortest edge of the unit-cell. (Cellulose appears to be anexception to this rule.) There are many variations and complic-ations of this simple fibre-structure, e.g., ring-fibres, spiral-fibres,the various forms of crossed fibres, etc. The theory and method ofdetection of these have been discussed very thoroughly by P6l$nyi,Weissenberg, and Mark,13 whilst many instructive examples of themhave been examined experimentally by Herzog and G0ne1l.l~ Ofcourse, much can be learned of these structures by purely opticalmeans, in which connexion W.J. Schmidt’s “ Die Bausteine desTierkorpers im polarisierten Lichte ” (Bonn, 1924) should bementioned, but X-rays have opened up immense fields in thisdirection. Many substances, hitherto held to be amorphous, haveproved to be either micro-crystalline or mixtures of crystals andtrue amorphous gels. Schmidt examined the spines of the sea-hedgehog in polarised light and observed simultaneous extinction.His deduction of single crystals has been beautifully confirmed by aLaue photograph. Similarly, the calcareous needles of certainsponges have proved to be “ bio-crystals.” These examplesrepresent one extreme, but all the various degrees of orientation,Irom single crystals to completely irregular polycrystals, have beenencountered, and investigated to a certain extent.The “ simplefibre structure ” represents the stage of development next belowthat of the true single crystal, then come the numerous types of“ multiple fibre structure,” an example of which is the enamel ofteeth. Herzog and Gone11 l4 give an X-ray picture of the enamell2 H. Mark, 2. Krist., 1925, 61, 75.l a K. Weissenberg, 2. Physik, 1921, 8, 20; Z . Krist., 1925, 61, 58; M.Pblanyi. 2. Physik, 1921, 7 , 149; 2. Krist., 1925, 61, 49; If. Mark, &bid.,1925, 61, 75.l4 Kolloid-Z., 1925, 36, 44; Naturwiss., 1924, 1153; Ber., 1926, 58, [B],222248 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of pig's teeth.It shows resemblances with the photograph of arolled foil, the most familiar type of multiple fibre structure.A remarkable group of growth-structures is that of electrolyticprecipitates.l29 l5 In this case, the results are influenced con-siderably by the experimental conditions such as current density,the nature of the electrolyte, of the cathode, and of foreign sub-stances introduced into the electrolyte. For instance, copper maybe deposited from acid copper sulphate solution so that the [ O l l ]axis stands perpendicular to the cathode-plane, but no orientationis observable if a solution of potassium cyanide and copper acetateis used. Similarly, silver separates irregularly from a silver-potassium cyanide solution, whilst in silver deposited from N/10-silver nitrate a t a current density of 0.010 amp./cm.2 [ I l l ] and to alesser degree [loo] appear as " fibre-directions." If now the currentdensity is increased to 0.022 amp.the statistical anisotropydisappears entirely. An experiment on " sputtered " platinumdid not yield a definite fibre-diagram and was not followed up.A well-known growth-structure, which is possibly also a naturaldeformation-structure, is that of graphite. Hassel and Mark lastyear examined it by'X-rays and found that the basal plane may beanywhere up to 30" on either side of the plane of the flakes. Thechief growth-direction in the plane of the flakes is parallel to thedirection [OlO] (orthohexagonal indices) with a spreading of &30°perpendicular to the plane and &lo" in the plane.This is aninstructive example of the way in which X-rays not only revealstatistical anistropy, but also may be used to determine the natureand degree of deviation from the ideal structures to which the naturalapproximate. A useful way of representing graphically the aniso-tropy and the observed spreading has been described by F. Wever.16As a final example of growth-structure we may mention pearl andmother-of-pearl. Dauvillier 16a has shown that natural pearlsgive X-ray photographs corresponding to the ordinary powderdiagram, whilst mother-of-pearl (nacre) gives diffuse Laue spots.This observation affords a means of discriminat'ing between naturaland artificial (Japanese) pearls. The latter are grown round anucleus of nacre.Thus, on taking an X-ray photograph of anartificial pearl we obtain both the powder diagram and the diffuseLaue spots. Shaxby 16a has continued these investigations ofDauvillier. He has confirmed his results that, with mother-of-pearl, a pseudo-hexagonal diagram is obtained when the X-rays arel5 Glocker and Ksupp, 2. Phyaib, 1924, 24, 121 ; R.. M. Bozorth, PJzysicuERev., 1925,26, 390; A,, ii, 1038.l6 2. PhysiE, 1924,28, 69.16a A. Deuvillier, Compt. rend., 1924,179, 817; J. H. Shaxby,ibid., p. 1602;A., 1925, ii, 93; Phil. Mug., 1925, 49, 1201CRYSTALLOGRAPHY. 249incident normal to the laminations, but a rectangular pattern whenthey fall parallel to the laminations.The observed spacings, too,agree with certain of those found by W. L. Bragg and Wyckoff foraragonite. There seems little doubt that the calcium carbonatethat forms the basis of pearl and of mother-of-pearl is in the formof aragonite (orthorhombic : pseudo-hexagonal).Much of our knowledge of the nature of deformation structuresand processes has been obtained through the study of strainedmetals. An enormous amount of work has been carried out in thisdirection, and it is impossible in this place to do more than hint a tthe mass of results and the far-reaching deductions that have beenmade from them. Briefly we may say that distortion of an originallyquasi-isotropic crystal-aggregate leads to a statistical anisotropyin the physico-chemical properties.An orientation of the crystalparts takes place which is at once revealed by X-ray examination.In ordinary technical experience, these effects, of course, are pro-duced and studied in the polycrystalline masses which constitutemetals in everyday use, but the most illuminating observations andideas have been obtained from the examination of the effect of stresson large single metallic crystals. The theory evolved from theseresults has been applied to the problem of metallic crystal aggregateswith great success. It is true that the simple uni-crystal theorydoes not explain everything that is observed in the deformation ofcrystal aggregates, but it undoubtedly clears up the major part ofthe problem. An instructive paper by Weissenberg l7 will wellrepay reading.What happens when a uni-crystalline wire, forinstance, is stretched is that gliding takes place in the systems ofglide-planes, and these are at the same time rotated more and moretowards parallelism to the direction of extension. Simultaneously,the cross-section of the wire is changed from a circle t o an ellipse andcharacteristic striations appear on its surface. Should there bemore than one type of glide-system present in the wire (as is generallythe case), these function in turn according to the values of the limit-ing stresses required to activate those most favourably placed. Thefinal result for infinite extension is that two of the glide-systems takeup positions which are symmetrical with respect to the axis ofextension.For instance, in the extension of a face-centred cubicmetal the chief glide-planes are the octahedra (1 1 l), whilst the chiefglide-directions are the face-diagonals [llo]. On careful extension,the zone-axis [ 1121, which lies symmetrically between two of theglide-systems, tends to set itself parallel to the axis of extension.Such a result was approximately realised by G. I. Taylor and C. F.Elam lS in the extension of an aluminium crystal. On the other1' Z. Krist., 1925, 81, 58.la €'roc. Roy. Xoc., 1923, A , 102, 643250 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.hand, Ettisch, P61&nyi, and Weissenberg l9 found [lll] and [lOOJ asend-directions for an Al-polycrystal, but P61Bnyi has shown that thisis probably a consequence of the fact that in a mass of crystals thereare frictional causes which involve a definite overstepping of thelimiting stresses of the two most favourably placed glide-systems, withthe result that all possible glide-systems function more or less andtry to arrange themselves so that the complete set of them issymmetrically disposed about the axis of extension.Similar conclusions hold for the processes which take place whenmetal foils are rolled.For rolled foils of aluminium, silver, copper,gold, and platinum,20 the (110) plane approximates to the plane ofrolling and the [112] axis to the direction of rolling. For rolledtungsten foil (body-centred), the corresponding plane and directionwere found by Gross to be (100) and [110], respectively.All theseeffects of cold-working can be studied directly by X-rays. In theinitial quasi-isotropic state, an X-ray photograph of a metal consistsof simple Debye rings (powder photograph), but after cold-workinga statistical anisotropy in the arrangement of the crystallites hasbeen brought about which shows itself by a characteristic change inthe X-ray diagram. A true powder photograph postulates allpossible orientations of crystallites, so that all planes may be in aposition to reflect X-rays. Such a condition does not hold aftercold-working, since certain crystal directions have been favouredduring the process. The consequence is that the Debye rings,uniform throughout in the photograph of an unworked metal,become discontinuous and show now as a symmetrical distributionof light and dark patches.Fig. 3, which is a photograph of a rolledgold foil taken on a cylindrical film co-axial with the primary beamof X-rays, and is reproduced from Mark's paper712 shows clearly theeffect described.As is well known, the cold-working of metals brings about markedchanges in their properties, notably in their hardness. It wasoriginally proposed by Tammann (" Lehrbuch der Metallographie ")that the cause of this hardening lay in the translations and rotationsof the glide-planes as outlined above, but it seems difficult to explainall the hardening in this way. Various other suggestions have beenput forward to supplement the " translation theory,"e.g., a destruc-tion of the lattice and the formation of a thermodynamicallyunstable state (by Czochralski); an " amorphous layer '' (byBeilby and Rosenhain) ; " local disturbances " (by Ludwik) ; and" hidden elastic strains " (by Heyn).But the observations andl9 2. Physik, 1921, 7, 181.2o N. Uspenski and S. Konobejewski, ibid., 1923, 16, 215; H. Mark andK. Weissenberg, ibid., 1923, 14, 528; 16, 314CRYSTALLOGRAPHY. 251considerations of P6lhyi and Gross lead to the assumption that,in the super-elastic deformation of a crystal, there takes place asplitting into thin layers which can glide over one another and havebeen definitely shown by X-rays to undergo bending. A specialdifficulty is inherent in this picture of the process, in virtue of thecircumstance that in the most strongly stretched outer layers theindividual glide-planes lie immediately against those glide-planeswhich are most shortened in the neighbouring element.Grosssupposes from this that small holes would actually arise, but heassumes that they are filled up by a fine folding of the surfaces of theglide-planes which makes them wave-like and uneven. Thisfolding has in fact been observed.21 We may picture the mechanismof cold-working thus, that there takes place a gliding along theglide-planes, generally accompanied by elastic bending of thegliding lamellae and a rotation of the crystal-elements into a certainorientation related to the chief deformation direction. The harden-ing is in the first place due to elastic bending of the glide-packetsand the consequent fine folding in the glide-planes.This it iswhich hinders further slipping. The hardening by rotation mustbe considered to be of secondary importance.An interesting outline of the recent investigations on deformationand recrystallisation has been contributed by F. Korber.22 Thereare many other papers worthy of discussion, but space forbids.23Other Inorganic Structures.Solid carbon dioxideis cubic and at liquid-air temperature the unit cell, which containsfour molecules, has a side oi 5-62 A.U. The structure. deduced hasthe symmetry of pyrites, (Th6). The molecules lie on non-intersectingtriad axes, each carbon atom between the two oxygen atoms belong-ing to it. Itshould be compared with the cubic form (p-cristobalite) of silicaSolid carbon dioxide 24 and solidThe arrangement is apparently a non-ionised one.2 1 Mark, P618nyi, and Schmid, 2.Physik, 1923,12, 115.22 Stahl u. Eisen, Febr. 12th and 19th, 1925.23 C. Benedicks, Nuture, 1925, 115, 230; A., ii, 188; E. Schiebold, 2.Metallk., 1924, 417, 462: A., 1925, ii, 1S6; J. Czochralski, ibid., 1925, 17,1 ; A., ii, 186; H. Rohrig, ibid., ,1925, 17, 63; A., ii, 282; R. Glocker, 2.Physik, 1925, 31, 3%; A., ii, 272; M. Pbliinyi, 2. Metallk., 1925, 17, 94;A., ii, 370; G. Sachs, ibid., p. 85; A., ii, 370; G. I. Taylor and C. F. Elam,Proc. Roy. SOC., 1925, A, 108, 28; M. PblBnyi and E. Sohmid, 2. Physik, 1925,32, 684; A , ii, 752; C. F. Elam, Phil. Mag., 1925, 50, 517; A., ii. 945; J .Iron Steel Inst., Sept., 1925; A., ii.946; PTOC. Roy. SOC., 1925, A, 109, 143;A., ii, 954.24 J. De Smedt and W. H. Keesom, Proc. Boy. Acad. Sci. Amsterdam, 1924,27, 839; H. Mark and E. Pohland, 2. Krist., 1925,61, 293.25 H. Mark and E. Pohland, ibid., p. 532252 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.which has recently been analysed. In carbon dioxide, the threeatoms are collinear, but in silica each silicon atom is surrounded bya tetrahedron of oxygen atoms. Solid ammonia also is cubic between-77" and -160". The cell again contains four molecules and has aside of 5-19A.U. The nitrogen atoms lie on non-intersectingtriad axes with the space-group T,. Three hydrogen atoms mustbe arranged trigonally about each nitrogen atom, but probably donot lie in the same plane with it.Barytes (BaS0,).26 The rhombic holohedral cell (a = 8.89,b = 5.45, c = 7.17 A.U.-Wyckoff) contains four molecules ofBaSO, and has the symmetry of Qh16.It is not pseudo-hexagonallike aragonite. There is evidence from the intensity measurementsthat the SO, group consists of a tetrahedron of oxygens round thesulphur (James and Wood), whilst according to Mark the metalatoms are not surrounded by equidistant anions, but each metal isclosely related to one particular anion. Strontium and leadsulphates, and potassium permanganate and perchlorate are alsofound to crystallise in the space-group Qh16, and anhydrous calciumsulphate in Qh17.Diop8ide [ CaMg( SiO,),] .27 The monoclinic prismatic cell hasdimensions a = 9.71, b = 8.89, c = 5.24, p = 105" 50'.There arefour molecules per cell and the space-group is C2Ii6.Manganese.28 Manganese, until last year, resisted all attemptsat X-ray analysis of its structure. This has proved to be due tothe fact that, as ordinary manganese, it always consists of a mixtureof allotropes. Three modifications have been identified. One ofthem (the y-form of Westgren, the a-form of Bradley) has beenobtained only by electrolytic deposition. It is face-centred tetra-gonal (four atoms per cell) with a = 3.77 and c = 3.53 B.U. West-gren considers it possible, although improbable, that it is in realitya hydride, but if it is pure manganese it gives a calculated densityof 7.21. It is apparently stable only at low temperatures, beingconverted by heat into the other two forms.This change does notappear to be reversible. According to Westgren and Phragmh,the allotrope stable at the ordinary temperature (they call it a-manganese) is cubic, a = 8.89, with 56 atoms per cell. The calcu-lated density is the same as that of the electrolytic form. At higher26 R. W. James and W. A. Wood, PTOC. Manchester Phil. SOC., 1924-25,69; Rime, Hentschel, and Schiebold, 2. Krist., 1925,61, 164; L. Pauling andP. H. Emmett, J . Amer. Chem. SOC., 1925, 47, 1026; A., ii, 485; R. W. G.Wyckoff and H. E. Merwin, Amer. J . Sci., 1925, 9, 286; A., ii, 485; H. Mark,2. Elektrochem., 1925, 31, 523; A . , ii, 1130.27 R. W. G. Wyckoff and H. E. Merwin, Amer. J . Sci., 1925,9,379; A., ii, 485.28 A. Westgren and G.Phragmh, 2. Physik, 1925, 33, 777; A , , ii, 1035;A. J. Bradley, Phil. Mag., 1925,50, 1018; A.,ii, 1124CRYSTALLOGRAPHY. 253temperatures, it changes to (Westgren’s) p-form, which also is cubic(a = 6.29 or 12-58) with 20 or 160 atoms per cell, the correspondingdensity being 7.29. Carbon dissolves in manganese in the same wayas in 7-iron, i.e., not by replacing metal atoms, but by penetratinginto the lattice spaces between them.Lithium potassium sulphate (LiKS04).29 The symmetry corre-sponds to the hexagonal space-group CG6, a = 5.13 and c= 8.60 B.U.There are two molecules of LiKSO, per cell. The potassium atomsare situated on a simple hexagonal lattice of axial ratio, a : c =1 : 0.838. The sulphate ions comprise two simple hexagonallattices of axial ratio, a : c = 1 : 1.6755, which fit together as if thesulphate ions were spheres in hexagonal close-packing.Thelithium ions alternate with the sulphate ions. Each sulphate ionis surrounded by six potassium atoms, and each potassium atom bysix sulphate ions. Each sulphur atom is surrounded tetrahedrallyby four oxygen atoms. The observed axial ratio of the structureis almost the theoretical value for hexagonal close-packing. Itappears from this as if the size of the unit is determined by the sizeof the sulphate ions alone, the metal atoms simply filling up as faras possible the interstices of the structure.Copper-zinc, silver-zinc, and gold-zinc alloys.3° As a result of theX-ray study of ten binary systems of alloys, Westgren and Phragmbnhave drawn the conclusion that the suggestions put forward to dateon the true difference between chemical compounds and solidsolutions are not based on sound arguments.In their opinion, thefundamental difference between solid chemical compounds and solidsolutions lies in their structure, that in an ideal chemical compoundstructurally equivalent atoms are chemically identical, whilst in anideal solid solution all atoms are structurally equivalent. Thesetwo structures represent extreme types, the former being com-paratively rare in metallic phases. Most phases seem to lie in theregion between the two extreme types, forming what might becharacterised as solid solutions in chemical compounds. X-Rayshave shown that in the copper-zinc, silver-zinc, and gold-zincsystems there are five different types of structure common to allthree. Two additional phases have been found in the gold-zincsystem.The five common systems, arranged according to increasingzinc content, are : a, face-centred cubic; p, czsium chloridestructure ; y , cubic with 52 atoms per cell ; E , close-packed hexa-gonal, axial-ratio 1.55-1-60 ; 7, close-packed hexagonal, axial-ratio, 1+30-1-90. A gold-zinc (7‘) phase with 50% of zinc wascubic with probably 32 atoms per cell ; another phase (y”), 53-54%28 A. J. Bradley, Phil. Mag., 1925, 49,1225; A., ii, 638.30 A. Westgren and G. Phragmh, ibid., 50, 31 1 ; A., ii, 746254 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Zn, appeared also to be cubic with about 90 atoms per cell.Inaccordance with the definitions, the Q-, q-, and probably the €-phasesrepresent ideal solid solutions, the f i s t one having copper, silver,gold, and the last two zinc as solvent. The other phases may beregarded as solid solutions in chemical compounds. The solventsof the p-phases are CuZn, AgZn, and AuZn.Other Organic Structures.Ethane and diborane, C,H, and B2H,.31 X-Ray powder photo-graphs of these two compounds in the solid state have shown thatstructurally they are very similar. There seems to be no doubt thatboron in diborane, like carbon in ethane, functions as a quadrivalentelement. They are both hexagonal with two molecules per cell.The centres of gravity of the molecules are arranged in hexagonalclose-packing, the molecules themselves possessing a t least three-fold symmetry.The distance between carbon atoms of the samemolecule is about 1-55 A.U., and about 3.5 A.U. between carbonatoms of neighbouring molecules. The corresponding numbers fordiborane are 1.85 A.U. and 3-7 A.U. The molecules in the crystalcorrespond to the ordinary chemical molecules.Long-chain cornpour~ds.~~ The X-ray investigation, described in aprevious Report, of these compounds has been continued, with manyinteresting results. The situation has been considerably clarifiedby the discovery that the crystals are mostly monoclinic or triclinic.As a consequence of this observation it has been decided that thelong spacing so prominent in photographs of chain compounds doesnot represent the true length of the molecule. The carbon chainsare in general inclined to the basal plane of the unit cell, and zlthoughthe increase in observed spacing per carbon atom is linear, thisregular change is merely the projection of the alteration in lengthof the carbon chain on the normal t o the basal plane.Stearic acidcrystals, for instance, are monoclinic, a = 5.60, b = 7.38, c =50.9 A.U., (3 = 59.7", with four molecules per cell and density ratherabove 1-05. The crystal habit appears to consist simply of (001)and (110). Stearolic acid appears to be triclinic, whilst for thenormal hydrocarbons the orthorhombic system seems to be indic-ated. Ten of the latter,33 between C,, and C,, have been investig-ated. The increase per carbon atom for the long spacing is 1.3 A.U.,a value considerably higher than that predicted from the theoryput forward by Muller and Shearer.Octadecane and eicosaneexist in two crystalline modifications. Sixteen aliphatic ketones,3431 H. Mark and E. Pohland, 2. Krist., 1925,62,103.32 A. Muller, Nature, 1925, 116, 45; A., ii, 748; R. W. G. Wyckoff andH. E. Merwin, Science, 1925,61, 613; A., ii, 1129.33 A. Muller and W. B. Saville, J., 1925,127,599.34 W. B. Saville and G. Shearer, ibid., p. 591CRYSTALLOGRAPHY. 255between C13 and C,, have also been examined. These fall into twosets, the increase per carbon (linear in both cases) being greater forthe methyl ketones than for the others. The results confirm theview that the active group, CO-CH,, produces a tendency for themolecules to arrange themselves end to end in pairs, and also showthat although the position of the *CO* group has no effect on thelength of the molecule, i t has a powerful effect on the intensitydistribution, a property which Shearer 35 has successfully appliedto the problem of localisation of such groups.R. E. Gibbs36 hasmeasured the spacings of fatty acids which are liquid at the ordinarytemperature. At hexoic acid deviations from the linear law appearand increase gradually down to propionic acid, an abrupt changeoccurring a t acetic acid. This corresponds to the changes observedin the freezing points.Inquiries similar to those outlined above are being carried out byother investigators 37 also, with similar results.J. J. Trillat 38 hasapplied the method to the examination of thin films of oleic, linoleic,and linolenic acids, containing one, two, and three double linkings,respectively. He has observed the changes which take place onoxidation a t these linkings .The unit cell of this compound contains thesubstance of four chemical molecules and exhibits, not the symmetryof the ditetragonal pyramidal class (as was hitherto believed), butthat of the tetragonal pyramidal (enantiomorphous) class. TheX-ray observations have been supplemented by a detailed crystallo-graphic and optical re-examination by T~tton,~O who has found thatthe substance is optically active, although it was not possible todetermine the angle of rotation.Calcium forrnate.*l The crystals are orthorhombic bipyramidaland not bisphenoidal, as was suggested by Plathan.The unit cellcontains eight molecules, a = 10.19, b = 13-41, c = 6.27 B.U.Space-group Qh5.In the monoclinic prismatic cell ofmaleic acid there are four asymmetric molecules. The crystalscan be bent and twisted in certain directions without fracture, and35 Proc. Roy. SOC., 1925, A , 108,655; A,, ii, 938; R. Robinson, Nature, 1925.116, 45; A., ii, 745.36 J., 1924,125, 2622.37 E. Friedel, Compt. rend., 1925, 180, 269; A., ii, 186; J. J. Trillat, ibid.,p. 280; A., ii, 1951; G. Friedel, ibid., p. 409; A., ii, 272; J. J. Trillat, ibid.,p. 1329, 1838; A., ii, 489, 752.I~dosuccinirnide.~~Maleic and fumaric acids.4238 Ibid., 1925,181, 504; A., ii, 1127.38 K.Yardley, Proc. Roy. SOC., 1925, A , 108, 542; A., ii, 746.40 Ibid., p. 548; A., ii, 747.41 K. Yardley, Min. Mag., 1925, 20, 290; A., ii, 430.p3 Idem, J . , 1925, 127, 2207256 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.twinning takes place with great facility on the (100) plane. Thecharacteristic features of this twinning are explained very reasonablyif the molecules actually in the twin plane are slightly different fromthose in the body of the structure-plano-symmetrical, in fact.Chemistry would suggest such a symmetry for the ‘‘ free molecules,’’from which the twins commence to grow symmetrically outwards.The space-group is CZh5 and a structure has been suggested to explainthe main X-ray results. Fumaric acid, which has hitherto defiedcrystallographic examination owing to the very complex twinning,etc., has yielded the result that it is anorthic with six molecules percell.Its crystallographic data have been determined solely by theBragg spectrometer. It should be noted that the unit cell containsthree times as many molecules as are required to produce triclinicpinakoidal symmetry, but examination of certain of its derivatives 43does not indicate association in the solid state for any other case.This is built on a simple tetragonallattice of space-group Dph7 with four chemical molecules per cell.The molecule appears to possess rhombic pyramidal (Czv) symmetry,one dyad axis parallel to the c-axis, which is the intersection of twoplanes of symmetry, (100) and (010).Pentaerythritol tetr~nitrate.~~Miscellaneous.Monoclinic Thallium Nickel and Thallium Cobalt Sulphates.4s-A full crystallographic examination has shown that these salts aretrue members of the isomorphous series of monoclinic, hexahydratecl,double sulphates and selenates, R,M(S04),,6Hz0.Non-magnetic Films of Ni~kel.~~---Nickel films have been prepared,by spattering in hydrogen, which are initially non-magnetic, butbecome magnetic when heated to 300400”.X-Rays show theordinary face-centred lattice for the magnetic films, but the non-magnetic films are apparently amorphous. From this result it isdifficult to avoid the conclusion that the ferro-magnetism of nickelis it property, not of the individual atom, but of the crystal-aggregate.Non-existence of the Clark-Duane Secondary X-Ray Spectra.47-In a previous Report were mentioned some experiments of Clarkand Duane which were claimed to have revealed the existence ofX-ray spectra in addition to those ordinarily found.Some of these43 K. Yardley, Phil. &fag., 1925, 50, 864; A . , ii, 1033.44 I. E. Knaggs, Min. Mag., 1925, 20, 346; A,, ii, 748.4 5 A. E. H. Tutton, Proc. Roy. SOC., 1925, A, 108,240; A., ii, 749.46 L. R. Ingersoll and S. S. De Vinney, Physical Rev., 1925, 26, 8 6 ; A . , ii,846.d7 A. P. Weber, 2. Physik, 1925, 33, 767; A., ii, 1034; A. H. Armstrong,W. Duane, and R. J. Havighurst, Proc. Nat. Acad. Sci., 1925, 11, 218; A., ii,1033 ; H. Kulenkampff, PhysikuZ. Z., 1925, 26, 657 ; A., ii, 1033CRYSTALLOGRAPHY.257spectra obeyed the Bragg law, whilst some were entirely anomalous.Neither type was ever satisfactorily explained, although a partialexplanation, based on our knowledge of X-ray absorption spectra,was put forward by W. Kosse1.48 Many workers have tried toreproduce Clark and Duane's results, but without success. Thereseems little doubt now that it is a spurious effect due to imper-fections in the crystals used. Careful work on very perfect alkalihalide crystals has proved that there is no anomalous reflexion ofX-rays characteristic of the constituent elements of the crystals.Furthermore, it has been shown that the structures of casiumtri-iodide and czsium dibromoiodide deduced from these supposedsecondary spectra are incorrect.49Etched Fig~res.~O-After discussing the kinetics of the dissolutionof a crystal, Tammann outlines a theory of the orientation of etchedfigures.According to this, the crystal surface is first attackedalong the lines of the crystal lattice in which the atoms entering intothe reaction are most closely packed. As the etching continues,figures are produced the outlines of which are parallel to the primarygrooves. A number of experimental cases are analysed, and on thewhole the agreement with theory is remarkably good. A veryingenious application of the study of etched figures has been madeby S. I. Tomkeiev 51 to the elucidation of the structure of aragonite.He has obtained striking quantitative agreement between theobserved etched figures and the structure he proposes for aragonite.Strange to say, this structure is in direct conflict with X-ray data,and it cannot be harmonised with the structure recently obtainedindependently by W. L. Bragg and R. W. G. Wyckoff. In spiteof arguments based on the etched figure, the conclusion seemsunavoidable that Tomkeieff 's structure is incorrect.Injluence of Atomic Arrangement on Refractive Inde~.~2--In aprevious Report it was described how a successful attack has beenmade on the problem of the calculation of the refractive indicesof crystals from refractivity data. This work has now beenextended. The indices of calcite, aragonite, and alumina have beencalculated on the assumption that the atoms composing the crystalsare ionised, and that each type of atom, when polarised by theelectric force of the incident radiation, acts as an electrical doublet48 2. Physik, 1924,23,278.49 R. M. Bozorth and L. Pauling, J. Arner. Chem. SOC., 1925, 47, 1561;50 G. Tammann, Z . anorg. Chem., 1925,146,413,420; A., ii, 942.61 Min. Mag., 1925,20,408; A,, ii, 1035.52 W. L. Bragg, Proc. Roy. SOC., 1924, A , 106, 346; A., 1925, ii, 92;K. Fajans and G. Joos, 2. Phy&k, 1924,23,1.A., ii, 748.REP.-VOL. XXII. 258 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.with a characteristic moment. It is also shown that it may bepossible later to reverse the process and deduce atomic arrangementfrom optical data.Atomic Structure Factor in the Intensity of X-Ray Rejlexion byCry~tals.~~-In this paper Hartree has attempted to give quantit-ative expression to the change in scattering power .of atoms withchange in glancing angle. It is clear that in dealing with the changein intensity of X-ray reflexion by crystals as the glancing angleincreases, we are not justified in assuming that all atoms are equiv-alent and subject to the same numerical adjustment. Hartree hasmade an analysis of the problem and from his conclusions drawn uptables of ‘‘ F-factors ” which are to be applied to the various typesof atoms taking part in the X-ray reflexion. For the sodium andchlorine ions the theoretical values are larger than the observed, andprobably the tables as a whole need modification to allow for theinfluence of certain obscure causes. These points are discussed byW. L. Bragg 54 in the communication succeeding Hartree’s.W. T. ASTBURY.W. H. BRAGG.53 D. R. Hartroo, Phil. May., 1925, 50, 289; A., ii, 735.64 Ibid., 306; A., ii, 735

ISSN:0365-6217    

DOI:10.1039/AR9252200240

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

MINERALOGICAL CHEMISTRY.Geochemistry.BISCHOF’S classical work on ‘‘ Chemical Geology ” dating from 1847,seems to have been almost forgotten, but there is now a revival inthe study of this comprehensive subject under the name “Geo-chemistry.” Recent books are: a new (fifth) edition of F. W.Clarke’s well-known “ Data of Geochemistry ” ; W. Vernadsky,“ La Geochimie ” (Paris, 1924) ; and, in Russian, A. E. Fersman,‘‘ Geochemistry of Russia.” The readable and very suggestivebook by Vernadsky contains the following chapters : I, Generalconsiderations on geochemistry ; 11, Silicon as silicates in the earth’scrust ; 111, Carbon and living matter ; IV, The radioactive chemicalelements. Fersman’s book deals with “ topomineralogy,” the dis-tribution of chemical elements, and the accumulation and associationof elements in certain places; genetic mineralogy in relation withgenetic types and cycles.European Russia is divided into twelvegeochemical regions or provinces.An elaborate paper by F. W. Clarke and H. S. Washington on“ The composition of the earth’s crust ” collects together theirprevious conclusions and gives the details on which these conclu-sions are based. The final calculations give for the average com-position of the solid crust to a depth of ten miles, including also thehydrosphere and atmosphere, the following percentages : 0, 49.52 ;Si, 25.75; Al, 7-51 ; Fe, 4-70 ; Ca, 3.39 ; Na, 2.64; K, 2.40; Mg,1.94; H, 0.88; Ti, 0-58; C1, 0.188; P, 0.12; C, 0.087; Mn, 0.08;S, 0.048; Ba, 0.047; Cr, 0.033; N, 0.030; F, 0.027; Zr, 0.023;Ni, 0.018; SrJ 0.017; V, 0.016; Ce, Y, 0.014; sum of remainder0.042%.It is seen that 99.5% of the crust consists of thirteenelements and but few common rock-forming minerals. These,together with those listed above and some others, are classed as“ petrogenic ” elements. “ Metallogenic ” elements are Cu, Zn,Ga, Ge, As, Se, Br and the others falling below them in the periodictable; they are of sporadic occurrence and are found only underBull. U.S. GeoE. Survey, 1924, No. 770, 841 pp.Part I of Vol. I (Petrograd, 1922); [Min. Mag. (Abstr.), 1925, 2, 4151.The work is to be completed in three volumes, each consisting of several parts.Prof. Paper U.S. Geol. Survey, 1924, No. 127; A . , 1925, ii, 63 (compareAnn.Report, 1923, 20, 261).I 260 ANNUAL REPORTS ON THE PROGRESS or OHEMISTRY.certain conditions as workable deposits of economic value. Thecompounds of these two “ natural ” groups of chemical elements,as represented in nature by minerals, are considered in detail.Petrogenic elements form mostly oxides and oxygen-salts, whilstmetallogenic elements form mostly sulphides, arsenides, and sulpho-salts.H. S. Washington wanders farther afield and considers the radialdistribution of certain elements in the earth’s i n t e r i ~ r . ~ From aconsideration of the composition of meteorites and rocks, thevelocity of earthquake waves a t different depths, and the density andcompressibility of minerals and rocks, he draws conclusions bearingon the distribution of matter within the earth.5 The followingzones are deduced : central core of nickel-iron, corresponding withmeteoric iron (3,400 km.thick) ; lithosporic shell consisting of patchesof silicates in a sponge of metal, corresponding with pallasites(700 km.) ; ferrosporic shell, corresponding with meteoric stones(700 km.) ; peridotitic shell (1,540 km.) ; basaltic shell (40 km.) ;and granitic shell or surface crust (20 km.).From the calculatedchemical composition, volume, and mass of each of these zones,the composition of the earth as a whole is deduced as : Fey 39.76(31-82 as free metal, and 7.94 in silicates) ; 0, 27.71 ; Si, 14-53 ; Mg,8.69; Ni (free), 3-16; Cay 2.52; Al, 1.79; S, 0.64; Nay 0.39; Coy0.23; Cry 0-20; K, 0-14; P, 0.11; Mn, 0-07; C, 0.04; Ti, 0.02;total, 100.00.It is noted that there is an excess of iron for com-bination with silicon and oxygen.The chemistry of the earth’s core has been further considered byL. H. BarnettY6 his calculations being based on the known densitiesof the earth as a whole and its crust and of the chemical elements,together with Washington’s data for the average chemical composi-tion of the crust. An irregular core of metallic substances (“ metallicfusion ”), probably more or less mixed with silicates, is estimateda t about 77.574 of the whole, whilst an irregular shell of silicates(“ slag ”), more or less mixed with metal, constitutes the remaining2205%. This core is estimated to consist of Fe, 90% ; Ni, Coy andCu, 7% ; the remaining 3% including gold and platinum a t 0.003%.G.Tammann considers that between the metallic core and the silicatecrust there is a zone of sulphides.’It is to be noted that speculations on the chemical compositionof the interior of the earth are based largely on a comparison of thecomposition of terrestrial rocks and meteorites. We may so pass4 J . Washington Acad. Sci., 1924, 14, 435; A . , 1925, ii, 234.5 Amer. J . Sci., 1925, [v], 9, 351; A., ii, 591. J . Geol., 1924, 32, 615.7 Z. anorg. Chem., 1924, 131, 96; 1924, 134, 269; A., 1924, ii, 163, 493(compare Ann. Report, 1923, 20, 262)MINERALOGFICAL WEMISTRY. 261from geochemistry to cosmochemistry. Both of these aspects ofthe subject are dealt with by A. E. Fersman in a small book entitled“ Chemical Elements of the Earth and the Cosmos.” * He considersthe laws of distribution and migration of the chemical elements inthe earth and in the cosmos, and traces a connexion between suchdistribution and their place in the periodic system and their atomicstructure.It is pointed out that everywhere-in the earth’s crust,in meteorites, the sun, planets, comets, and stars-there is a pre-ponderance of elements of the helium atomic group, namely thosewith atomic weights divisible by 4 and up to atomic number 28 (Ni).P. N. Chirvinsky has calculated an average composition for cosmicmatter from statistical data of the weights and number of meteoritesof different types that have been observed to fall on the earth’ssurface during the period 1492 to 1921.The percentage composi-tion arrived a t may be expressed by the formula M,Si,O,, which mayalso be written as a mixture of orthosilicate, metasilicate, and freemetal, M,SiO, + MSiO, + M, where M is a collective metal withmean atomic weight 40-58. Metals and metalloids are present invery nearly equal proportions by weight. This is taken to representa pseudo-element, “ cosmium,” with equivalent atomic weight25.59. An interesting and suggestive essay, entitled “ The evolutionand disintegration of matter,’’ has been written by F. W. Clarke.loIn the several recent papers descriptive of individual meteoritesan outstanding feature is the discovery in 1921 of an enormous massof meteoric iron in the desert of Adrar, at about 45 km.south-westof Chinguetti in Mauretania, French West Africa. As reported byA. Lacroix,ll it measures 100 metres in length and 40 metres inheight, and is perhaps 160,000 cubic metres in volume. Containingabout 20% of silicates, it represents a new type of meteorite inter-mediate between the siderites and pallasites ; further, the silicateportion consists largely of hypersthene rather than olivine.Amongst the mineral constituents of meteorites, quartz has beenmentioned as present in the St. Mark’s meteoric stone.12 Of thephosphates sparingly present in certain stones, i t is now found thatmerrillite has the composition Na,0,3Ca0,P,05, and is thus distinctfrom any known terrestrial mineral.13 In one stone it was foundassociated with chlor-apatite.Hydrocarbons (“ bitumen ”) have8 Peterburg, 1923 (in Russian); [Min. Mug. (Abstr.), 1924, 2, 2661.S Astronornische Nachrichten, 1924, 222, 103 ; [Min. Mag. (Abstr.), 1925,lo Prof. Paper U.X. Ceol. Xurvey, 1924, No. 132-D, 51.11 Compt. rend., 1924, 179, 309; A., 1924, ii, 693.l2 G. P. Merrill, Arner. Min., 1924, 9, 112.2, 3891.E. V. Shannon and E. S. Larsen, Amer. J . Sci., 1925, [v], 9, 250;A., ii. 321262 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.occasionally been recorded in meteorites ; and the suggestion is nowmade that these may have been formed by the action of water oncarbides after the arrival of the meteorites on the earth’s surface.14A problem to which some attention has lately been given, butwhich still remains unsolved, is that of the origin of tektites.15 Thisgeneral term includes the moldavites or “ bottle-stone ” found inriver-gravels in Bohemia and Moravia. These consist of a clearglass, and being of a rich green colour they have been used as gem-stones under the names “ pseudo-chrysolite ” and “ water-chryso-lite.” They are remarkable for their corrugated and deeply sculp-tured surfaces.At one time they were thought to be artificial, theproducts of an ancient glass-making industry, and this view is stillheld by some authors. Other kinds of tektites are the australites or“ obsidianites,” found in large numbers loose on the surface of theground in certain parts of Australia and Tasmania ; and the billiton-ites found in river-gravels and tin-gravels in Billiton and other placesin the East Indies.These consist of dark green or black glass withglossy surface, and are of curious button-like, dumb-bell, and othershapes with surface markings in concentric rings. They have beenthought to be of volcanic origin, the curious shapes being acquiredwhen molten drops of lava were shot out from volcanoes. Butthere are no recent volcanoes in Australia. The suggestion made byF. E. Suess in 1900 that tektites are of meteoric origin was onlyslowly accepted, but now there are many adherents to this view.None has been observed to fall. If they did fall they evidentlycame down in showers, like the meteoric stones which fell at Hol-brook, Arizona, in 1912, when more than 14,000 stones were pickedup. The main difficulty, however, is that presented by the chemicalcomposition of these glassy bodies.They are high in silica, 70% to88%, with only little lime and alkalis. They thus differ in composi-tion from artificial and volcanic glasses and very widely from anyrecognised meteorites.Constitution of Silicates.The papers on this subject are increasing in number, but it mustbe said that no real advance appears to be made. Various theoriesare being put forward and each is tested serially for different groupsof minerals. Much ingenuity is displayed in attempting to explainall cases by any one theory. The mica group has been studied most,and samples of the different types of formulae that have beenproposed are quoted below.l4 P. E. Spielmann, Nature, 1924,114, 276; A., 1924, ii, 867.1 5 V, Goldschmidt, Beitr.Kryst. Min., 1924, 2, 148.of recent papers in lllin. Mag. (Abstr.), 1922,1,406-9.A series of abstractMINERALOGICAL CHEMISTRY. 263B. Gossner doubts the existence of complex molecules correspond-ing with the empirical formule of silicates, for example E(AlSi308for orthoclase; and he expresses the composition by the combin-ation, analogous to double salts, of certain simple and stable mole-cules, such as SiO,Ca, Al,O,, AlO,H, SiO,, etc. In addition to thepapers mentioned in the last report, he has continued the series l6with the groups of chlorites, " brittle micas," monoclinic pyroxenesand amphiboles, alkali-amphiboles, babingtonite, gehlenite-melilitegroup, and micas. For example, the " building scheme " (Bauplan) forthe pyroxenes is based on the complex (double salt) SiO,Mg,SiO,Ca,in which Si0,Mg is rep€aceable by A120, or SiO,(Fe,Mn), and Si0,Csby Si0,Mg.The following are some of the formulae he gives for themicas :Muscovite . . . [Si0,,Si0,K,,A1,03],4Si0,,4A10,H.Biotite . . . [Si0,K,,Si0,Mg],3Si03Mg,3A10,H.Lepidolite . . . [Si03K,,Si0,Li,],4Si0,,4A10F.According to the theory of J. Jakob silicates are referred to theprototypes [Si04]R1,, [Si05]Rr6, and [Si06]Rr8, with or withoutadded SiO, groups. For the micas he postulates the following" part-molecules " (Teilmolekule) :and [Mg(Si05Si02)3]RT18. He gives detailed analyses, together withdensity and optical determinations, for eight specimens of mangano-phyllite (a variety of biotite containing some manganese) fromSweden.17 As an example of the type of formula, the following (inwhich, curiously, manganese does not appear) is deduced from oneof the analyses :50.07 A1(Si04), K,,, + 39"' 'A %.962 . [ ':86f3 I-W.Kunitz l 8 has made a noteworthy attempt to correlate thephysical and optical characters with the chemical composition forminerals of the mica group. Only few data, in which d l the deter-minations were made on the same sample of material, are availablefrom the literature. Thirty-two new analyses were therefore made16 Centr. Min., 1924, 97, 129, 267; 1925, Abt. A . , 1, 39, 73; 2. Krist.,1924, 60, 76, 302, 361; 1925, 61, 538; Chernie der Erde, 1925, 2, 103; A.,ii, 821.17 2. Krist., 1925, 61, 165.Jahrb. Min. Be&-Bd., 1924, 50, 365264 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of micas of various kinds, and in many cases the density and opticalconstants were also determined. It is shown that in biotite, etc., theestimation of water is often too low, due to the reaction 2Fe0 +H,O To obviate this, the mineral was heated withchlorate and the gases passed over platinised asbestos. Three mainisomorphous groups of micas are recognised : I, alumina-micas or themuscovite series, in which Al is replaceable to a limited extent(up to 10%) by Fern. 11, magnesia-iron micas or the biotite series,in which Mg and Fen are completely replaceable. 111, lithia-micasor lithionites; here a special tervalent group [2Li,Si], denoted as" Le," is completely replaceable by Fen.A summary of the resultswith formula? of the hypothetical end-members is quoted below.They show that with increasing iron there is a corresponding, oftenlinear, increase in the density and in the refractive indices. Therefractive indices are to some extent also modified by the completeisomorphous replacement of F and OH. Partial isomorphousreplacements are also Si-Ti, Si-Al, Al-Cr-Mn, and K-Na(but not K-H and A1-Mg, as required by some theories). Allmicas can be considered to contain the fundamental moleculeKAlSiO, (kaliophilite) with the addition of molecules correspondingwith kaolin, serpentine, and chlorites.Fe,O, + H,.End-members. n(u).Muscovite KH2Al,(Si0,), 1-5514A1:Fem = 10: 1 + 1.5719Phlogopite KH,AlMg,( SiO,), 1.5440Lepidomelane KH,AlFe~,(SiO,), 1.629Lepidolite KH,Al,Le( SiO,), 1.5290Zinnwaldite + 1.5485Protolithionite KH,AlFeI13( SiO,), 1.592(not known) KH,Fe~,(SiO,), -- .Biotite \y IN B ) . Nr). 2E.1.6810 1.5873 80' 40'1.6105 1.6148 58 10- 1.578 ?- (1.68) ?1.5520 1.5558 78 201.5745 1.5792 50 6 - 1.625 0- - -- - -d.2.8022.8852.7913.3402-8012.973.305-A. F. Hallimond l9 calculates from published analyses of the" acid " micas the molecular proportions on the basis (Si,Ti)O, = 600.In the soda- and potash-micas K,O+Na,O is then near 100. Themolecular proportions of R,03 plotted against RO give points alonga line from K20,3A1,0,,6Si0,,2H,O (muscovite) toK,0,2A1,03,R0,6Si0,,2H,0(phengite), showing a replacement of R,O, by RO, as previouslysuggested for glauconite.20 In the lithia-micas SiO, = 600, K,O =100, Li,O = 100, and R203 plotted against RO gives two series *K,0,Li,0,2A1,03,6Si0272H,0 (lepidolite) toK,0,Li,0,A1,03,R0,6Si0272H,0(cryophyllite), and lepidolite to K20,Li20,2A1,O3,3RO,6SiO2,2H2(l9 Min.Mag., 1925, 20, 305; A., ii, 819.*O Ibid., 1922,19, 330; A . , 1922, ii, SG1MINERALOGICAL CHEMISTRY. 265(protolithionite).for example, for muscovite :Graphical formule are written for each of these ;A10 A10 A10 A101 IK-0 0 b 0 0 0 0 O-Al( OH),\si/ \di-o-hi / \di-o --ki<O\si/K-0 \ ~ i - ~ - ~ ~ - ~ - ~ ~ - ~ - $ i - ~ - ~ i - ~ - ~ i ~ IK-O/ \O/ \O/ O / \O-Al(OH),and for protolithionite :Li A10 A10 Li0 0 0 0 1 1 1 II O-AI(OH),K-O/\O o/ ‘0 o/ ‘0 0 / \O-Al(OH),1\/ R \’ R \/ RA.N. Winchell 21 bases his studies of the mica group on the pro-position that isomorphism depends on the atomic volumes of thereplacing elements, rather than on their valencies-the replacing“ bricks ” in the crystalline structure must be of approximately thesame size, as given by their atomic volumes. Fluorine, chlorine, orhydroxyl may replace (or “ proxy ” for) oxygen rather than hydrogen;potassium does not “proxy” for hydrogen, nor titanium for silicon.Calculations from the best published analyses of biotites show arange in the atomic percentages (omitting 0, H, F) : Si 3143 to 38.5(Le., 5/16 to 6/16), Al 12.7 to 25 ( L e a , 2/16 to 4/16), Mg + Fen +Mn 16.5 to 36.8 (Le., 3/16 to 6/16>, and K (+ Na + Ba + Ca) near12-5 (2/16).The series therefore ranges from H4K2Mg6&Si60,(phlogopite) to H4K2Mg5A14Si,0,4 (eastonite), with the correspondingiron compounds H,K,Fe6~,Si602, (annite) and H K Fe5Al4?,O,(siderophyllite). Here titanium and ferric iron “iroxy formagnesium, and not for silicon and aluminium. The several analysesare plotted on a square diagram a t the four corners of which are theabove hypothetical compounds. The optical constants plotted onthe same diagram show some relations with the chemical composi-tion. In the above formulae the fundamental unit has in all cases16 atoms (H and 0 being omitted), and these micas are thereforereferred to the “ octophyllite ” or biotite system. In another groupof micas, the “ heptaphyllite ” or muscovite-lepidolife system, thereare 14 atoms in the fundamental unit.Here there are four end-members : H4K2A1,Si,02, (muscovite), H4K2Li6Si60, (polylithion-ite), H4K,A14Si,0p5 (phengite), and H4K,FeLI,A14Si,02, (protolith-ionite), which are placed a t the corners of a tetrahedron. Themajority of plotted analyses fall on or near two of the surfaces of21 Amer. J . Sci., 1925, [v], 9,309,415; A , , ii, 592.I266 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the tetrahedron, and are representative of two three-componentsystems , musc ovit epolyli t hioni te-pr o t olithionit e and muscoviteprotolithionite-phengife, which are referred to as the muscovite andlepidolite systems, respectively. The optical data of these micasare represented by contour lines on the same tetrahedron. Theoctophyllites and the heptaphyllites are the two main groups of themicas between which there are no mixed crystals; the former areusually dark-coloured and the latter are usually light-coloured, andthere are important differences in their optical characters.This idea of “ volume isomorphism ” in the silicates had beenpreviously considered by F.Zambonini22 and by E. T. Wherry2,in connexion with the well-known case of albite (NaAlSi,O,) andanorthite (CaAl,Si,O,)-this pair forming a complete series ofmixed crystals in the plagioclase felspars. Here NaSi and CaAl areevidently the replacing pairs. The sum of their atomic volumes 24as calculated from W. L. Bragg’s (1920) atomic radii are approxim-ately the same, and the two atoms taken together will fit into thesame crystalline structure.Further, i t is to be noticed that the sumof the valencies of the two pairs of replacing atoms is the same. Asimilar case is given by the isomorphism of diopside (CaMgSi,O,)and acmite (NaFeInSi20,), and also by calcite (CaCO,) and sodiumnitrate (NaNO,). This, however, seems to be only a re-statementof the fact pointed out by J. D. Dana as long ago as 1850 that themolecular volumes (molecular weightldensity) are approximatelyequal for these paks of isomorphous substances.The same replacement of NaSi by CaAl as in the plagioclases isalso worked out by A. N. Winchell 25 for the several minerals of thezeolite group.For example, the published analyses of thomsoniteare plotted on a square at the four corners of which are the lime andsoda molecules Ca,.!il,Si,,O,,Aq, Na6A16Silo03,,Aq, Ca5A1,,Si,0,,,Aqand Na,,Al,,Si,O,,,Aq, the varying ratios Al,O, : SiO, and CaO f Na,Obeing shown along the two co-ordinates. The analyses fall alonga curved line between the points Na,Ca,Al,oSi,o0,0,25H,0 andNa,Ca5Al, ,Si2,0,,,20H,0, which are regarded as the end-membersof an isomorphous series. Quite different results have been arriveda t for thomsonite by other authors. E. T. Wherry,2s by plottingNa,O against SiO,, obtains two well-marked clusters : one aroundthe composition NaCa2A15Si50,,,6H,0, corresponding with thom-8, 81.22 Atti (Rend.) R. Accad. Lincei, 1922, [v], 31, (i), 295; Amer. Min., 1923,23 Amer.Min., 1922, 7, 113.24 E. T. Wherry, ibid., 1923, 8, 1, calculates the atomic volumes : 0 = 1,25 Ibid., 1925,10, 88, 112, 145, 166.26 Ibid., 1923, 8, 121 ; 1925, 10, 342.H = 5, Si = 7, A1 = 11, Ca = 22, Na = 23 x 10-24 C.CMINERALOGICAL CHEMISTRY. 267sonite proper ; and the other around Na2Ca3A1,Si,0,,9H2~, corre-sponding with faroelite. Each of these minerals possesses definiteoptical constants, and there is no range of variation, as would be thecase in an isomorphous series. Deviations shown by some analysesare ascribed to mechanical mixtures with nafrolite or mesolite.From the same series of published analyses S. G. Gordon27 calculatesthe molecular ratios with Na20 = 1 ; CaO then ranges from 1-00to 5-97.When the total Na20 + CaO is plotted against SiO, andagainst H20 the analyses are grouped along straight lines, whichindicate the isomorphous mixing of the end-membersCaA1,Si20,,3H20 (“ calciothomsonite ”)and Na2Al2Si3Ol0,H2O.In other groups a similar wide diversity of opinion is also shownin recent papers. The melilite group was the subject of muchexperimental work at the Geophysical Laboratory in Washington.2sB. Go~sner,~~ however, regards as improbable the existence of suchcomplex molecules and he traces a connexion between these tetr-agonal minerals and the monoclinic (“ pseudo-tetragonal ”) pyrox-enes. They are regarded as double compounds CaO + pyroxeneof the form Ca0,[Si03Ca,Si03Mg], where Si0,Mg is replaceable byA120,, and Si206MgCa by Si206A1Na.Ca0,[Si03Ca,A1203],and meUte as 2Ca0,[Si20,MgCa,Si206A1Na].A. N. Winchell,3Oon the other hand, regards the molecules Ca2A12Si0, (gehlenite) andCa2MgSj 20 (gkermanite) as well-established end-mem bers of thegroup ; but the hypothetical molecule Ca3Al2Si3OI2 or(sarcolite) he thinks is doubtful. The last may be split up intoCa2A12Si07, Ca3Si20,, and SiQ,. Including Si with R, these, aswell as gehlenite and Bkermanite, reduce to the general type R,O, ;and they are therefore regarded as replaceable in the space-lattice ofmelilite. The excess of silica is supposed to fall into the inter-atomic spaces, thereby producing a considerable effect on the density,but little effect on the refractive indices.Correlations of the optical constants with the chemical composi-tion in isomorphous groups of minerals have been shown graphicallyon plots of various kinds by several authors, especially by A.N.Winchel131 in a scries of papers on the pyroxenes, amphiboles,scapolites, and micas. Accurately determined data, all determinedGehlenite is written( 9Ca,Na2)3A12Si30,22’ Proc. Acad. Nat. S c i . Philadelphia, 1924, 76, 103; A., 1924, ii, 868.2 8 Ann. Report, 1920, 17, 213; 1923, 20, 268.29 Ckeinie der Erdc, 1925, 2, 103; A., ii, 821.30 Ainey. J . Sci., 1924, [v], 8, 375; A., ii, 152.3l Ibid., 1923, [v], 6, 504; 1924, 7, 287; 1025, 9, 309, 415; Amer. Alitb.,1924,9, 108; 1925,10, 335.I* 268 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.on the same sample of material, and thus suitable for purposes ofcorrelation, have been given by H.S. Washington and H. E. Mer-win,32 and by N. Sundius 33 for various pyroxenes and amphiboles.Unfortunately, with many recent mineral analyses the authors omitto state the density of the material analysed. Many publishedmineral analyses have been made solely for purposes of identification,and these should not be taken into account when attempting toarrive at the constitution of minerals.The chemical composition of isomorphous groups of silicates(tourmaline, chlorite, mica) were studied by E. S. Fedorov34 bygraphically plotting the analyses. With three or four independentvariables, different methods of plotting involving a special geometrywere devised. The composition of various silicate minerals isrepresented by points on or in a “ chemical tetrahedron,” and thepositions of these points are expressed geometrically by symbolsresembling crystallographic indices.At the four corners of thetetrahedron are grouped the univalent, bivalent, tervalent, andquadrivalent elements, respectively 35 (oxygen being omitted).The symbol for quartz will then be (OOOl), for corundum (alsohaematite) (OOlO), spinel (0120), albite (1013), anorthite (0122), etc.The three main types of micas are (loll), (0445), and (4403), corre-sponding respectively with muscovite, biotite, and phlogopite.These points are all on the surface of the tetrahedron. Pointsrepresenting the more complex chlorites fall inside the tetrahedron,and all in a plane with the indices (6456).Amesite, -H@g > Fe 1 2 4 s io,or(4221),showstherelation6 x 4 + 4 x 2 + 5 x 2 + 6 x 1 = 0 ;and the same holds with the other chlorites, clinochlore (8523),delessite (5222), corundophyllite (20.11.8.6), etc.The System Alumina-Silica.The trimorphous minerals andalusite, fibrolite, and kyanite, withthe composition Al,SiO, or Al,03,Si02, are well known, and incertain rocks they are of abundant occurrence in nature. Kyaniteis typically a product of the dynamic (or pressure) metamorphism ofrocks, whilst andalusite and fibrolite are often the products ofcontact (or thermal) metamorphism. Neither andalusite norkyanite has been prepared artificially; and it is now said that thesupposed artificial fibrolite is not Al,O,,SiO,, but 3A1,03,2Si0,.32 Amer.Min., 1923, 8, 63, 104, 215.53 Qeol. F6r. PGrh., 1924, 46, 154.34 Bull. Acad. Sci. Russie, 1918, [vi], 12, 616, 625, 645, 1891; [Min. Mug.3 5 Similar to Fig. 2 in Ann. Report, 1923,20,267, but with univalent elements(Abdr.), 1925, 2, 4251.at one corner in place of MgO or CaOMINERALOGICAL CHEMISTRY. 269There is thus a recurrence of the once vexed question of the com-position of fibrolite. In the old text-books on mineralogy bamlite,buc holz i t e , fibr oli t e , monr oli t e , sillim ani t e , wort hit e , and xenolit ehave at one time or another ranked as distinct species. Analysesshowed widely varying ratios of alumina to silica, due, as now known,to the intimate intermixture of silica with the finely fibrous and densematerial (and the same is true of the artificial product). Theseminerals are now all united under the species fibrolite, and moderntext-books are all agreed on the formula Al,O,,SiO,, although noton the mineralogical name to be applied to the species.The nameFaserkiesel dates from 1792 and its equivalent fibrolite from 1802;whilst the name sillimanite, now in common use in petrography, wasfist given by G. T. Bowen in 1824.The system alumina-silica was studied experimentally in theGeophysical Laboratory at Washington in 1909,36 and the conclu-sion then arrived at was that the only compound is Al,SiO,. Thecrystalline product was identified with fibrolite, the crystallographicand optical characters agreeing with those of the natural mineral(although it was noticed at the time that the crystals were mixedwith glass and that they had refractive indices slightly lower thanthose of natural fibrolite) .Later work in the Geophysical Laboratory by N. L.Bowen3'and his collaborators, in 1924, showed that this artificial product,eliminating the glass, has the composition 3 ~ , o , , ~ s i o , . And it isfurther asserted that all " fibrolite " previously prepared artificiallyhas the same composition. A mixture of alumina and silica in equalmolecular proportions was found to crystallise from fusion as a,mixture of 3A1,03,2Si0, and cristobalite (SiO,) or glass. Above1810", this breaks down into corundum (Al,O,) and liquid. It wasalso found that natural fibrolite, when heated at 1545", breaks downto 3A1,03,2Si0, and a highly siliceous glass.This compound3A1,03,2Si0, is also described by the same authors as a naturalmineral under the name mullite. This was found as microscopiccrystals, which had earlier been referred to fibrolite, in the buchites(inclusions of fused slaty rocks in igneous intrusions) from the Islandof Mull in Scotland. None of the three minerals with the com-position AI,O,,SiO, could be obtained artificially, and they areignored in the equilibrium diagram of the system Al,O,--SiO, ; butin view of their abundant occurrence in nature, their existence can-36 E. s. Shepherd, G. A. Rankin, and F. E. Wright, Amer. J . Sci., 1909,[iv], 28, 293; Ann. Report, 1909, 6, 202. G. A. Rankin and F. E.Wright,ibid., 1915, 39, 1 ; Ann. Report, 1915, 12, 243.37 N. L. Bowen and J. W. Greig, J. Amer. Ceramic Soc., 1924, 7 , 238;N. L. Bowen, J. W. Greig, and E. G. Zies, J . Washington Acad. Sci., 1924,14, 183; A,, 1924, ii, 416270 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.not very well be denied. The conditions operating in nature areevidently very different from those in the laboratory and in thestudy.No essential difference is shown between the crystallographicand physical characters of fibrolite and mullite. Both are ortho-rhombic with the same prism angle and the highly perfect cleavageparallel to the brachy-pinakoid. The optical orientation is the samefor both, and also the wide difference between the birefringencesy-cx and p-cx on the planes (010) and (OOl), respectively.Theyalso give identical spectra by the X-ray powder method.38 Theonly difference is that the refractive indices of mullite ( a 1.642,y 1.654) are slightly lower than those of fibrolite (cx 1.657, y 1.677).When, however, the crystals of mullite contain small amounts ofimpurities (Fe,03 and TiO,) the values, cx 1-661 and y 1.682, actuallyexceed those for fibrolite.We have here a very unusual case showing an anomalous relationbetween chemical composition and crystalline structure. Crystalsin which there are isomorphous replacements are expected to bevery similar in their geometrical and physical properties; but herewe have identity of properties with a different molecular ratio of&,O, : SiO,. Malachite[CuCO,,Cu(OH),] and chessylite [2CuC03,Cu(OH),], though bothmonoclinic, are very different in structure and all their properties;matlockite (PbCI,,PbO) and mendipite ( PbC12,2PbO) are tetra,gonaland orthorhombic, respectively ; alamosite (PbQ,SiO,) and barysilite(3Pb0,2Si02), monoclinic and hexagonal ; and many other similarexamples could be cited.It would seem that some mistake has beenmade. The existence of fibrolite (Al,O,,SiO,) cannot be denied.39If the existence of mullite as 3A120,,2Si0, is confirmed, the sugges-tion may be made that the physical characters assigned to it arereally those of fibrolite. Many examples can be collected from theliterature of cases in which the chemical composition has beendetermined on material of one kind, whilst the crystallographicproperties have been determined on material of another kind.40Difficulties of this kind are frequently met with when dealing withfinely crystallised mixtures.The artificial reproduction of fibrolite or mullite is of mineralogicaland chemical interest, but it is also of considerable economic import-ance in the manufacture of refractory materials and ceramic ware.38 This is confirmed by F.Rinne, 2. Krist., 1925, 61, 113.39 Crystals of fibrolite from which excellent gems have been cut have recentlybeen described (Min. Mag., 1920,19, 107).40 For example, the characters of the so-called orthorhombic or P-tin, asquoted in the text-books, were determined on orthorhombic crystals ofstannous sulphide (Min. Mag., 1921,19,113).No similar case can be called to mindMINERALOGICAL CHEMISTRY.271It has been prepared on a large scale in a crystalline form by smeltingaluminous rocks or minerals with coke in a cupola furnace.*l Areview of the literature on the presence and development of artificial" sillimanite " in ceramic ware has been given by A. B. Peck.42 Healso describes an occurrence of andalusite-rock in California, whichis mined with an output of about 70 tons per week, the materialbeing used in the manufacture of the porcelain cores of sparking plugsfor automobiles. This mineral when heated a t about 1390" istransformed into a parallel aggregate of fibres of mullite withinterstitial glass, the density changing from 3.29 to 3.20. Since thevolume change accompanying this transformation is only slight, thepowdered mineral can be mixed with the clay body before fking.Kyanite is transformed at about 1370" into an irregular interlockingaggregate of mullite fibres with interstitial glass, there being here agreater change in volume (d 3.59 to 3.09).J. W. Greig 43 finds thatthis decomposition takes place at no definite temperatures, but islowest for kyanite and highest for fibrolite. Above 1050°, onlymullite is stable. The decomposition of kyanite and of andalusiteis accompanied by an absorption of heat.The stability relations of the three minerals andalusite,fibrolite, and kyanite have been studied by F. Ne~rnann.~~ Thespecific heat and heat of solution (in 40% hydrofluoric acid) weredetermined for each, and also for the mixture of mullite and silicaprepared from equal molecular proportions of alumina and silica.These data are applied in Nernst's heat theorem, and from the" A-U " (work-energy) diagram for the pair andalusite-fibrolite, itis concluded that fibrolite is the stable modification up to 1487", andthat andalusite is stable above this temperature.Kyanite as com-pared with fibrolite is completely unstable. Direct experimentsshow, however, that when heated at 1200" andalusite changes intomullite and glass ; and kyanite shows the same change at 1400".Colour in Minerals.Minerals that possess no colour of their own may, when welldeveloped as single crystals, be perfectly colourless, clear, and trans-parent. Examples are the rock-crystal variety of quartz and theIceland-spar variety of calcite.Often, however, the crystals arecloudy or opaque, due t o inclusions of foreign matter. If thisforeign matter consists of ferric hydroxide, the crystal may be41 A. Malinovsky, J . Am.er. Cera.m. SOC., 1920, 3, 40; Trans. Ceram. Soc.,1920,19, 140.42 Amer. Min., 1924,9,123; 1925,10,253; J . Amer. Ceram. SOC., 1925,8,407.43 J . Amer. Ceram. SOC., 1925,8, 465; A , , ii, 987.44 2. anorg. Chem., 1925,145, 193; A., ii, 849272 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.yellow, brown, or red, as often seen in quartz and calcite. Or again,crystal aggregates may be intermixed with impurities of variouskinds, as in the multi-coloured jaspers and marbles. I n such casesthe cause of the colour is obvious and is shown by an ordinarychemical analysis.I n other cases the crystal, though brightlycoloured, may still be perfectly clear and transparent : for example,the amethyst, cairngorm, and citrine varieties of quartz, which areused as gem-stones ; wine-yellow and violet calcite ; brilliant sky-blue halite (rock-salt); and fluorite with its wide range of delicatecolours. The colour of emerald and ruby has been attributed totraces of chromium (and in the artificial gem-rubies the colour isproduced by the addition of chromic oxide). But in the majorityof cases chemical analysis gives no clue as to the cause of the colour.This " dilute colouring " is due, according to the theory of C. Doelter,to the presence of a colloidal substance, and the different colours tothe degree of dispersity or size of the particles of the colloid.Butit may be doubted if colloids can exist in a solid crystalline medium.Crystals of organic compounds are capable of taking up traces ofaniline dyes, and it may be suggested that minerals are merely dyedwith traces of inorganic (in some cases organic) colouring matter.Some colours are clearly due to the interference of light broughtabout by structures in the stone (as in mother-of-pearl) ; and it isevident that the colours of minerals cannot be all explained by anyone theory. The main difficulty is presented by certain minerals thatexhibit remarkable changes in colour with change in temperatureand when exposed to radium emanations, ultra-violet rays, cathode-rays, X-rays ; and further, these changes are often accompanied bystriking luminescent and phosphorescent effects in the mineral. Suchchanges have been studied by C.Doelter and others, but with veryerratic results, and the same effects cannot always be repeated.The various colour-varieties of quartz have recently been investig-ated in detail by E. F. Holdem45 The colour of citrine he attributesto sub-microscopic particles of ferric hydroxide. Deep-ambercoloured material was found to contain 0.026% PezO3, whilstspecimens with a pale yellowish tinge contained only 0.008% toO - O l l ~ o . Further, the darker colour was closely imitated with acolloidal solution of ferric hydroxide of the same degree of con-centration, and the absorption-spectrum of light transmittedthrough this solution is identical with that of citrine.Pink crystalsof quartz contained O*O43 yo Fe203 and showed microscopic inclusionsof hzematite. This colour was imitated by mixing finely powderedhEmatite with sodium silicate. Rose-quartz showed in 27 analyses45 Amer. Min., 1923,8,117; 1924,9, 75, 101; 1925,10, 127,203; A., 1924,ii, 620MINERALOGICAL CHEMISTRY. 273of material from various localities a loss on ignition of @10---@25y0and solid impurities 0.13-0.29~0. Small amounts of MnO, TiO,,Fez03, COO, Li,O, andA1,03 were estimated. The manganese rangeswith the depth of colour (pale pink to deep pink) from 0.0002 yo to0.0006y0 as MnO; and the conclusion is drawn that the colour isdue to some manganic (Mnm) compound.The absorption-spectrumand dichroism of rose-quartz are similar to those of substancesknown to contain Mnm. Rose-quartz is decolorised a t about575", and when exposed to radium it becomes smoky. Contrary tothe statement in books on precious stones, the colour is not affectedby sunlight.46 The rose colour has been imitated in a silica gel bythe addition of manganic borate (O~Ol-O~OZ~o MnO). A rose-quartz with a bluish tinge contained 0.029y0 TiO, and showed underthe microscope abundant inclusions of fine hairs of rutile, to whichthe bluish colour is ascribed. Smoky-quartz is immediately de-colorised at 440" and slowlyat 235", and the colour is restored byradium radiations. The small amounts of iron, titanium, andmanganese shown by analysis bear no relation to the depth of thecolour ; whilst uranium (UO, 0~001-0~006~0) and free silicon aremost abundant in darker specimens. Free silicon was estimated byboiling the finely powdered mineral in aqua regia, when colloidalsilicic acid passes into solution ; the darker specimens gave Si 0.01 yo.The conclusion is drawn that the smoky colour is due to the scatter-ing of light by atoms of free silicon and that these have been liberatedby the action of radioactive substances.Amethyst is often associ-ated with iron minerals and it frequently contains inclusions ofgoethite and hcematite. It is decolorised at S6y0 and the violetcolour is restored by radium. Darker-coloured specimens becomeyellow when ignited and then show the same absorption-spectrumas citrine.Manganese and titanium are present in only smallamounts, which do not vary with the depth of colour. The averageamounts of Fe,O, in specimens free from visible inclusions range withthe colour from o-oo7y0 to o-14y0. The colour of amethyst is similarto that of ferric ammonium alum and is evidently due to some ferriccompound, which when heated breaks down to ferric hydroxide.The yellow and purple calcites from Joplin, Missouri, have beenstudied by W. P. Headdon4' with special reference to the phos-phorescent and luminescent phenomena which they display. Whenthe mineral is heated at 250" for twenty minutes, many of theseproperties a,re destroyed and the colour is discharged. The pro-4 6 A richly coloured specimen of rose-quartz exhibited in the BritishMuseum collection of minerals has been exposed to light since the year 1799.4 7 Arner.J . Sci., 1923, [v], 5, 314; 1923, 6, 247; 1924, 8, 509; Proc.Colorado Sci. SOC., 1923,11, 399 ; A., ii, 561274 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.perties are again restored by exposing the calcite to radium, and thematerial then acquires a yellow colour. Some colourless andpreviously unresponsive calcites when exposed to radium acquire ayellow colour and become responsive. Detailed chemical analyseswere made on large amounts of material (500 grams or even 25 15.).A strongly phosphorescent, yellow calcite from Joplin contained, inaddition to CaCO,, about 99-80yo : cerium earths 0.019, yttriumearths, 0.013, MgO 0.113, FeO 0-046, MnO 0.045, ZnO 0.014y0.The purple Joplin calcite gave : cerium earths 0.0397, yttriumearths 0.0149, MgO 0.0949, A1203 0-0076, FeO 0.0148, MnO 0.0477,ZnO 0.0048, CuO 0*0090%.The difference in colour cannot beexplained by these impurities in the calcite. It has, however, beennoticed that the purple calcite alone shows the absorption-spectrumof neodymium, and the suggestion has been made that this is thecause of the purple colour, though there is no direct evidence tosupport this view. A curious feature was noticed accidentally witha colourless calcite from Ingleside, Colorado. This is sometimesphosphorescent after exposure to sunlight, but only after it has beenwashed on the surface with dilute hydrochloric acid.48A change in colour due to oxidation of ferrous iron has beenobserved by A.J ~ h n s e n . ~ ~ Pale yellow to green crystals of sphenefrom the Alps when heated to redness in air for half an hour becomedeep reddish-brown, and they then show a different pleochroismand a slight difference in the optic axial angle. When again heatedin hydrogen, the original colour is very nearly restored. Materialthat contained before heating FeO 0.48, Fe,03 0.04%, gave afterheating in air FeO 0.40, Fe,O, o.1370, and after subsequent heatingin hydrogen Be0 0.52, Fe203 o.03~0. These changes are takent o indicate that there has been a diffusion of material in thesolid.A somewhat similar case is shown by the mineral chlorophreite,though here the change in colour due to oxidation takes place spon-taneously on exposure to air.This mineral, which occurs as patchesin dolerite near Edinburgh, is pale olive-green with glassy lustreon freshly fractured surfaces. On exposure, the colour changes todark green in about fifteen minutes, and after ninety minutes it isblack with pitchy lustre. It was found that this change takes placealso in the dark when the mineral is exposed to air; but not in anatmosphere of carbon dioxide, even on exposure to bright sunlight.The change is therefore due to oxidation, and not to the action oflight, The change from pale green to black can be induced artificiallyby heating a fragment of the mineral in the oxidising part of a Bunsen-48 Amer. J.Sci., 1924, [v], 8,509; A , , ii, 89.49 Jahrb. Min. Be&-Bd., 1923, 48, 136MINERALOGICAL CHEM'ISTRY. 275flame. Analysis of the fresh mineral shows the presence of Fe,Q312.37, FeO 9.18%.50A fugitive colour in sodalite is described from Dungannon inOntario.51 A rock, consisting of nepheline, cancrinite, and calcite,showed on freshly fractured surfaces bright pink spots, but in directsunlight these vanished in ten to thirty seconds. When the speci-mens are placed in the dark, the colour gradually returns, thoughnot to the same brilliancy. The material of the pink areas wasidentified as sodalite, but the analysis shows no constituent, beyonda trace of manganese, to account for the colour. This colour changeis evidently due to the action of light, and no further explanationcan be offered.It was first noticed a century ago in sodalite fromGreenland,52 and later in sodalite from India and in hackmanitefrom Russian Lapland.The action of radium radiations on the colour of mineralshas been studied by many workers, and a good account has recentlybeen given by S. C. Lind and D. C. B a r d ~ e l l . ~ ~ The colour producedby exposure to radium chloride or bromide is afterwards dispelledby heat or by exposure t o sunlight. The most marked effects aregiven by fluorite and kunzite. Fluorite of all colours becomes bluein 1-3 days; the material when afterwards heated to 70" gives ablue luminescence, and a t 180" the colour is discharged. Kunzite,the lilac-coloured variety of spodumene, becomes first colourless andthen emerald-green ; and is afterwards very brightly thermolumines-cent.Diamond becomes green only when exposed to a-radiation(not p- and ?-radiation through glass); this colour is apparentlylight-permanent, but is dispelled a t 450". A theory to account forthese changes assumes that certain groups of electrons are displacedand their vibration frequencies modified.New Minerals.A list of 211 new mineral names (not necessarily new minerals)covering the period 1922-1925, but including also a few earliernames that had remained buried in the scattered literature, hasrecently appeared.54 A selection of these not mentioned in previousReports is given below. A hrther crop of radioactive mineralsfrom the deposits of uranium ore in the Katanga district of the5O R.Campbell and J. W. Lunn, Min. Mag., 1925,20,435 ; A., ii, 1093.5 1 T. L. Walker and A. L. Parsons, Univ. Toronto Studies, Geol. Ser., 1925,5 2 F. Mohs, " Treatise on Mineralogy," translated by W. Haidinger, 1825,53 J. Franklin Inst., 1923, 196, 375, 521 ; Amer. Min., 1923, 8, 171, 201 ;54 L. J. Spencer, " Tenth list of new mineral names; with an index ofNo. 20, 5.2, 227.1924, 9, 35.authors." Min. Mag., 1925, 2Q, 444276 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Belgian Congo includes the new names : droogmansite,b5 dumont-ite,56 fourmarierite, and sklodowskite.57Some of these names are rather uncouth and they do not seem tobe well chosen for international use.58 The international aspect ofScience is of prime importance.An original paper is written in thelanguage of one country, but it is more widely read in the sum ofother countries.A system of Latin binomials (as in botany and zoology) was inuse a century ago for minerals, but this has long since been given up.Another method that has been tried without success is that of usingpurely chemical names. This is favoured by Groth in his ‘‘ Chem-ische Krystallographie ” ; for example, he substitutes for hannayitethe name Tetrahydrogendiammoniumtrimagnesiumtetraorthophos-phat-Oktohydrat. But this does not completely define the mineralhannayite-there may be others of the same composition. Further,future analyses of hannayite may prove this composition to beincorrectto the confusion of indexers.For such minerals astourmaline even Groth does not attempt a chemical name. Thesystem now in vogue, in spite of its confusion and faults, is the bestyet devised. It certainly is a convenience to use such names asdiamond and graphite for the crystalline modifications of carbonfound in nature; and calcite and aragonite for those of calciumcarbonate.Af~iZZite,~~ hydrated calcium silicate, 3Ca0,2Si02,3H20, or2H2CaSi04,Ca(OH),, found as a single, columnar aggregate of clear,colourless crystals in the Dutoitspan diamond mine at Kimberley,South Africa. The crystals are monoclinic and the mineral is quitedistinct from the several hydrated calcium silicates previouslyknown. It has an alkaline reaction and is slowly decomposed bywater.BardoZite,60 a dark-green, chlorite-like mineral with the empiricalformula K20 ,5Mg0 ,FeO ,2Fe03,A1,0,, 12Si0, ,2 1H,O, intermediatebetween biotite and chlorite in composition. It is of interest be-cause of its occurrence as a primary constituent in an igneousrock, namely in diabase at Bardo in central Poland.6 5 H.Buttgenbach, “Min6ralogie du Congo Belge.” Mdm. SOC. R. Sci.LiLge, 1925, [iii], 13.6 6 A. Schoep, Compt. rend., 1924,179,693 ; A., ii, 64 ; Bull. Soc. franc. Min.,1925, 48, 77.67 A. Schoep, Compt. rend., 1924,179,413 ; Bull. Soc.franc. Min., 1924,47,162; Bull. SOC. chirn. Belg., 1924,33, 562; A., 1924, ii, 868; 1925, ii, 235.6* L. J. Spencer, “ International agreement in mineralogical and crys-tallographical nomenclature.” Min.Mug., 1925, 20, 353.6s J. Parry and F. E. Wright, Min. Mag., 1925,20,277; A., ii, 429.6o J. Morozewicz, Bull. SOC. franc. Min., 1924, 47, 49; Spraw. Polsk.Inst. Geol., 1924, 2,217; 1925,3, 1MINERALOGICAL CHEMISTRY. 21 7Benjaminite, sulphobismuthite of lead, silver, and copper,Pbz(Ag,Cu),Bi4Ss, belonging to the klaprotholite group, and foundas grey masses in white quartz from Nevada.BromeZZite,62 beryllium oxide, BeO, found as small, white, hexa-gonal prisms in the iron mines at Lhgban in Sweden. It is veryhard, about 9 on the scale. X-Ray analysis shows the crystal-structure to be of the zinc oxide type.Canni~xarite,~~ a sulphobismuthite of lead, PbS,2Bi2S,, of recentformation as a sublimate in fumaroles on Vulcano, Lipari Islands.The acicular crystals appear to be orthorhombic.Chaprn~nite,~~ hydrated ferrous silico-antimonate,5Fe 0, 5SiO2, S b,O, ,2H,O,occurring as an olive-green, pulverulent material (probably ortho-rhombic) intermixed with native silver in the Keeley mine, SouthLorrain, Ontario.F0shagite,~5 hydrated calcium silicate, 5Ca0,3Si02,3H,0 orH,Ca5(Si0,),,2H,O, as a white fibrous (orthorhombic) mineral fillingveins in idocrase a t Crestmore, California.Fourmrierite, a hydrated uranium lead mineral occurring asminute, red, orthorhombic crystals intimately associated withkasolite, curite, and torbernite in the oxidised uranium ore of Kasolo,Katanga, Belgian Congo.H. Buttgenbach,66 by whom the name wasgiven, found also some silica, but this may belong to the associatedkasolite.Analyses by 5. M6lon 67 on material separated as far aspossible from other minerals suggested the formula Pb0,5U0,,10H20 ;while one by A. Schoep68 gave Pb0,4U0,,5H20, which, written in theform (UO,,Pb)O,H,O, suggests a, relation to becquerelite andschoepite.Chlorophoeni~ite,6~ basic arsenate of manganese and zinc withsmall amounts of calcium, magnesium, and iron, with the highlybasic formula R3As,08,7R(OH),. It is found a t Franklin Furnace,E. V. Shannon, Proc. U.S. Nat. Museum, 1924, 65, art. 24; A., 1924, ii,560. For other sulphobismuthites of lead see Cannizzarite and Goongarritebelow ; still others have been described by K. Johansson, A ~ k i w Kemi, Min.Geol., 1924, 9, no. 8.62 G. Aminoff, 2. Krist., 1925,62, 113.63 F.Zambonini, 0. de Fiore, and G. Carobbi, Rend. Accad. Sci. pis. Mat.64 T. L. Walker, Univ. Toronto Studies, Geol. Ser., 1924, No. 17, 5.6s A. S. Eakle, Amer. Min., 1925,10,97.6 6 Ann. SOC. GBol. Belg. (Publ. Congo Belge), 1924, 47 (for 1923-4), C 41.87 Ann. SOC. Ge'ol. Belg. (Bull.), 1025,47, B 200.68 Bull. SOC. franp. Min., 1924, 47, 157; Bull. SOC. chim. Belg., 1924, 33,69 W. F. Foshag and R. B. Gage, J . Wmhington Acad. Sci., 1924,14, 362;Napoli, 1925, [iii], 31, 24; A., ii, 709.658; A., 1925, ii, 236.A., 1924, ii, 773278 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.New Jersey, as small, monoclinic prisms, which are pale green bydaylight and pale purplish-red in artificial light (hence the name).EZutoZite,70 a form of calcium carbonate believed to represent thehigh-temperature a-form stable above 970".It is represented bycavities with the form of fir-trees ( Z X & T ~ ) in the nepheline-syenitesof the Kola peninsula in Russian Lapland. The dendritic crystalsthat have been leached out of these cavities were evidently anoriginal constituent of the igneous rock.EZZ~worthite,~~ hydrated metatitano-niobate of uranium (UO,18.5%), calcium, and iron, RO,Nb20,,2H,O, occurring as yellow orbrown, optically-isotropic masses in pegmatite a t Hybla, Ontario.In its degree of hydration it is intermediate between hatchettoliteand ampangabeite.Goong~rrite,~~ a sulphobismuthite of lead, 4PbS,Bi,S,, occurringas fibrous to platy (monoclinic 1 ) massses in a gold-quartz vein nearLake Goongarrie, Western Australia.Kempite ,73 hydrated oxychloride of manganese,MnC1,,3Mn0,,3H20,as small, emerald-green, orthorhombic crystals in manganese orefrom California .Kochite, 74 hydrated aluminium silicate, 2A1,0,,3Si02,5H20, as agranular aggregate of minute, cubic crystals a t Kochi-mura, Japan.HungunoZung b eini t e , manganese and potassium sul p hat e ,2MnS04,K,S04, as minute, pale-rose tetrahedra from Vesuvius.Itis analogous to the cubic double salt langbeinite, [2MgS04,K,S0,].NuZZite, orthorhombic, 3A120,,2Si0, (see p. 269).Burnsuyite,76 sodium titanosilicate, Na,0,2Si0,,2Ti02, occurringas brown, orthorhombic crystals resembling sphene in nepheline-syenite-pegmatite in the Kola peninsula, Russian Lapland.Sch~ZZerite,~~ hydrated arseno-silicate of manganese,SMnSiO, ,Mn3As,0,, 7H20,as pale-brown masses filling veinlets in zinc ore at Franklin Furnace,New Jersey. It has a pearly basal cleavage and is optically uniaxial,and is analogous to friedelite ~9MnSi0,,MnC1,,7€120].7O A.E. Fersman, C. R. Acad. Sci. Russie, 1922, 59; Bull. Acad. Sci.Russie, 1923, [vi], 17, 251.71 T. L. Walker and A. L. Parsons, Univ. Toronto Studies, Geol. Ser., 1923,No. 16, 13.7 2 E. S. Simpson, J . Roy. SOC. Wedern Atistralia, 1924,20, 65.73 A. F . Rogers, Amer. J . Sci., 1924, [v], 8, 145; A., 1924, ii, 693.74 S. KBzu, K. Seto, and K. Kinoshita, J . Geol. SOC. Tokyo, 1922,29, 1, 148;7 5 F. Zambonini and G. Csrobbi, Rend. Accad. Sci. Pis. &la€. Napoli,76 A. E. Fersman, C. R.Acad. Sci. Russie, 1922,59 ; E. E. Kostyleva, ibid.,7 7 R. B. Gage, E. S. Larsen, and H. E. Vasmr, Amer. Min., 1925,10, 9.Sci. Rep. Tdhoku Univ., 1924, [iii], 8, 1.1924, [iii], 30, 123; A., 1924, ii, 867; Gazzetta, 1925, 55, 414; A., ii, 898.1923, 55MINERALOGICAL CHEMISTRY. 279Swedenborgite, 78 antimonate of aluminium and sodium,NaAl,SbO,, as colourless, hexagonal crystals from Liingban,Sweden.Wen~elite,’~ hydrated phosphate of manganese, etc.,(Mn,Fe,Mg),(P0,),,5H,0,as rosettes of pale rose-red, monoclinic crystals from the phosphate-bearing pegmatites at Hagendorf , Bavaria. Similar crystals, alsorose-red and monoclinic from the same locality, but with thecomposition R3(PO4),,3H,O, have been called baldaufite.80New Books.“ A chart showing the chemical relationships in the mineralkingdom ” has been prepared by P.C. Putnam (J. Wiley & Sons, NewYork; Chapman & Hall, London, 1925). This will be found usefulto chemists as well a.s to mineralogists. It gives the answer to suchquestions as : “ How ma,ny and what are the minerals containinggermanium, and what are their compositions ? ” ; “ Does silveroccur with oxygen in any mineral ? ” ; or ‘‘ Do phosphides or silicidesoccur as minerals ‘2 ” It serves as an aid to determinative miner-alogy and the microchemical analysis of minerals. And, further,gives a t a glance a statistical survey of the affinities and the anti-pathies that hold in the mineral kingdom. The chart is printed on asheet measuring a yard across and is mounted on linen.Along theedges various chemical elements, acid radicals, etc., are listed,there being 93 and 54 such entries in the two directions. Rulingvertical and horizontal lines, 5022 “ boxes ” are thus provided, inwhich practically all known minerals are placed. A mineral ofcomplex composition will of course appear in several ‘‘ boxes.”The minerals are referred to by numbers 1-1632 ; and alphabeticaland numerical indexes are given in the text. It is thus possible tosee a t a glance what minerals contain, say, both lead and sulphur,lead and uranium, lead and aluminium, etc. The idea is a good oneand the chart will serve many useful purposes.A new edition has appeared of P. Niggli’s “ Lehrbuch der Miner-alogie.” The first volume (Borntraeger, Berlin, 1924) is really atreatise on crystallography, but two more volumes dealing withspecial mineralogy and mineral associations (“ Minerocoenology ” )are to follow. The treatment is fresh, and the book is full of noveland brilliant ideas, giving stimulus to research. H. Buttgenbach’s“ Les mineraux et les roches,” a general and elementary text-book,has reached a third edition (Dunod, Paris ; H. Vaillant-Carmanne,LiBge, 1924). A fifth edition of the late H. Rosenbusch’s well-In the original paper the name isG. Aminoff, 2. Krist., 1924, 60, 262.F. Mullbauer, ibid., 1925, 61, 333.F. Mullbauer, Zoc. cit., 334.given erroneously as Wentzelit, after Pater Hieronymus Wentel280 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.known " Mikroskopische Physiographie der Mineralien und Gesteine "is in preparation. The first half of vol. I (1921-4) has been revisedby E. A. Wulfing and deals with the methods of investigation,involving crystal-optics, separation of minerals, microchemical testsapplicable to powdered minerals and to thin sections, etc. Thesecond half by 0. Mugge gives a systematic description of the rock-forming minerals. In the first part so far issued (1925) the mineralsof the cubic, tetragonal, hexagonal (and trigonal) systems are dealtwith.W. Eitel in " Physikalisch-chemische Mineralogie und Petrologie "(T. Steinkopff, Dresden and Leipzig, 1925) gives a condensed reporton the work done during the past ten years on the many physical-chemical problems bearing on the formation and equilibrium ofminerals and rocks. Numerous references are given to the originalliterature and there is it long index of authors. The same author inhis prize essay " Uber die Synthese der Feldspatvertreter " (Akad.Verlagsgesell., Leipzig, 1925) gives a detailed review of the literatureon the synthesis of the felspathoid minerals (leucite, nepheline,gehlenite, melilite, sodalite, cancrinite, scapolite, etc.), with adiscussion and equilibrium diagrams of the various systems in whichthey have been obtained artificially by fusion. An account is alsogiven of his own work on carbonate-silicate fusions. The bearing ofthese experiments on the paragenesis of these minerals in naturalrocks is considered.A pamphlet 81 on " The physical chemistry of igneous rock form-ation " contains a series of ten papers by various authors, whichwere presented for general discussion at a joint meeting of theFaraday, Geological, and Mineralogical Societies in London. Con-tributed remarks and the discussion that arose are also included.L. J. SPENCER.a1 Reprinted from Trans. Paraday SOC., 1925,20,413

ISSN:0365-6217    

DOI:10.1039/AR9252200259

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

COLLOID CHEMISTRY.*THE development of colloid chemistry has been reviewed byW. D. Bancroft,l and a series of classical papers has been translatedand edited by E. Hatschek.2 A nomenclature and system forcolloid chemistry suggested by P. D. Zacharias would substitutethe term metachemistry in place of colloid-, capillary-, or dis-persoid-chemistry, so that one would be free from dogmatic restraintand able to use freely chemical and physicochemical methods.Solutions would be divided into three classes based on the size ofthe particles in solution. What are now termed colloid particlesbecome ‘‘ Teilchen ” (Gk. T ~ X V ) , these being elementary, compound,and complex. The author’s paper is decidedly heterodox in places.A. LumiAre believes that there are two colloidal states of matter,the molecular colloidal state and the micellary colloidal state, theclassification being based on the structure of colloids, not on theirproperties.In the first state the solute is dispersed in a solventas individual molecules but of high molecular weight, colloidalitybeing a consequence. The properties depend on the dimensionsand chemical functions of the molecules. The second state dealswith pseudo-solutions, stabilisation factors being prominent, andthe properties depend on the constitution of the molecular aggre-gates, the nature and importance of impurities, and the electriccharge.Another classification into two groups is suggested by L. Michaelisand Sh. D ~ k a n . ~ They are obligative colloids (which cannot existin true solution, e.g., mastic) and facultative colloids (which consistof suspensions of a solid, e.g., silver iodide, in its saturated solution).In the case of obligate colloids, hydrogen- and hydroxyl-ions holda special place amongst ions in respect t o their influence on electriccharge and consequently on the effect on general properties.* This Report has been prepared on behalf of the British AssociationCommittee on Colloid Chemistry (Prof. F.G. Donnan, Chairman; Dr. Wm.Clayton, Secretary; Prof. J. W. McBain, Mr. E. Hatschek, Prof. W. C.McC. Lewis) by the Secretary.J . Franklin Inst., 1925, 199, 727.“ Foundations of Colloid Chemistry ” (London, 1925).Kolloid-Z., 1925, 36, 39; A., ii, 196.Rev. gdn. Coll., 1925, 3, 161. Kolloid-Z., 1926, 37, 67; A , , ii, 963282 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Facultative colloids are influenced by electrolytes in general, andresults in this connexion are given relating to colloidal bariumsulphate.extends his previous work on the zone of colloid-ality by a short paper on the “ Simple Kinetic Principle of ColloidProcesses,” dealing with the behaviour of heated iron and steelto illustrate the general principle that maximum colloidality followswhen both the specific surface and the kinetic activity reachmedium values.Several contributions have been made by P.P. von Weimam.In an extensive paper 7 he reviews his work of several years underthe title “ The Precipitation Laws.” His four laws governing theprecipitation of solid substances from solution are given :The mean magnitude of the individual crystals ofprecipitates will progressively decrease as the concentration ofthe reacting solutions progressively increases.With progressively increasing concentration of thereacting solutions, the mean magnitude of the individual crystalsof precipitates (as determined after a definite time interval fromthe moment of mixing together the reacting solutions) will passthrough a maximum.For a set of dispersion media in which a solid sub-stance, X, has different solubilities, the precipitation curves forthat particular dispersion medium in which, other things beingequal, the dispersion is least, will occupy the lowest position beneathall other precipitation curves, and their beginning will be displacedto the left.Law I V .On substituting for the absolute concentration of thereacting solutions ( G ) the relative Concentration of the precipitat-ing substance, (&-L)/L (where Q = C/Z, since equal volumes aremixed) the precipitation curves without maximum for the sub-stance X precipitating from different dispersion media, whereL = Ll, L,, L3 . . . L,, will very closely approach one another,up to the point of sometimes almost merging into a, single curve.Here (&-I,) is the concentration of the dispersed phase pro-duced, L being the normal solubility of this phase. The ordinateof the curves expresses the mean size of the crystals, and theabscissz give the concentration of reacting solutions.The reviewis a valuable summary of von Weimarn’s researches. Anothersummary 8 deals with his general views on the colloid state, whilstthe influence of added substances on the permanence of disperseJ. AlexanderLaw I .Law 11.Law 111.Kolloid-Z., 1925, 36, 334; A., ii, 779.7 Chemical Reviews, 1925, 2, 217.8 Kolloid-Z., 1925, 36, 237; A., ii, 660COLLOID CHEMISTRY. 283systems receives theoretical treatment along lines familiar tostudents of von Weimarn’s work.gAn interesting contribution from H. Siedentopf lo deals withthe proof of the form of ultramicrons. The mathematics and useare described of an apparatus which can be used to measure micro-scopic and ultramicrbscopic dimensions, being based on the Michel-son experiment on the interferometer measurement of fixed starstoo small for the ordinary telescope.H.R. Kruyt and H. C. Tendeloo 11 criticise the point of viewtaken by Loeb on the question of the significance of the hydrogen-ion concentration as a factor in determining the condition oflyophilic sols. They believe “ the action of electrolytes on lyophiliccolloids does not differ in essence from that on lyophobic colloids.The peculiar matter from which the particles of a protein are builtup brings about that the H’ and OH’ ions have quantitativelyspecial function,” but not an all-determining function. Loebbelieved the isoelectric point to depend on a definite p H value,but Kruyt and Tendeloo find that the isoelectric point can bereached a t various pH values by adding a quantity of anotherelectrolyte just sufficient to produce discharge.Moreover, it ispossible to pass through the isoelectric point as a minimum by meansof ions other than H’ or OH’. Emulsoid sols must be regarded ashydrated suspensoids, electric charge still being one of the stabilityfactors. The authors consider that the essence of the problemof electric charge lies in the study of electrokinetic phenomena,these being observed in the whole region of colloids, lyophilic andlyophobic.Another pertinent criticism of Loeb’s work is given by W.Kopaczewski,l3 who believes that since the colloid state is anintermediate state defined by dispersion limits, its laws will beneither exclusively physical nor exclusively those of classicalchemistry.Sols.The preparation and properties of some protected silver solshave been described by I.D. Garard and G. E. Duckers.I3 Alkalinesilver nitrate solutions were reduced with formaldehyde or glucose,agar-agar, dextrin, and gum arabic being present as protectivecolloids. Gum arabic-silver sols were exceedingly stable againstKolloid-Z., 1925, 37, 151; A., ii, 969.lo Ibid., 1925, 36 (Zsigmondy Pestschr.), 1; A., ii, 637.l1 J. Physical Chem., 1925, 29, 1303; A,, ii, 1059.l2 “ L’Etat Colloidal et L’Industrie ” (Paris, 1925), Tome I, 40-50.l3 J . Arner. Chem. SOL, 1925, 47, 692; A., ii, 391284 ANNUAL REPORTS ON THE: PROGRESS OF CHEMISTRY.the addition of various electrolytes over a wide range of concen-tration. According to V. Mor&vek,l4 stable silver sols may beprepared by reducing ammoniacal silver nitrate with chloroformin the presence of gelatin, heating at 90" for about 20 minutes.Continuing the study of the analysis and constitution of SOIS,E.Fried and W. Pauli l5 find that silver sols prepared by thereduction of ammoniacal silver chloride with hydrazine hydrate,contain ammonium ion. Experiments on dialysis, conductivity,cataphoretic mobility and addition of electrolytes are described.The condition of the silver in protargol and collargol (therapeuticsols) has been investigated by I. M. Kolthoff and 0. Tomi6ek,16carrying out potentiometric titrations with iodine. Work closelyrelated in scope and methods has been published by R. B. Smithand P. M. Giesy.17W.Grundmann 18 shows that it is possible to prepare silicic acid solsof definite uniformity.Attention must be paid to the ratio ofhydrochloric acid and sodium silicate used. The solution must bedialysed immediately in collodion membranes of standard thick-ness, using distilled water at a definite rate of flow. Contaminat-ing vapours must be avoided. The sols are very stable and showvery little light-dispersion.By the addition of hydrochIoric acid to sodium silicate solutionstwo types of silicic acid sol are p0ssib1e.l~ 50 grams of sodiumsilicate in 200 C.C. of water + 70 C.C. of 20% acid gives a sol ofpH 4.5, whilst using only 150 C.C. of water gives a sol of pH 6 orhigher. The first sol shows a viscosity increasing with time; thesecond decreases with time owing to occluded silicate.The solsare negatively charged and stable at 20". By adding hydrochloricacid to the second sol to reduce its pH to about 4.5, sol I results;conversely, addition of caustic soda to sol I gives the second type.The constitution and stability of silicic acid sols have beeninvestigated by Wo. Pauli and E. Valk6.20 Sols were prepared byGraham's method, by saponification of the methyl ester of silicicacid, and by decomposition of silicon tetrachloride, Graham's solhas a well-defined conductivity and the constitution of the particlesmay be expressed : [z(SiO, + nH,O)ySiO,H] + yH+ (or yNa+).Dialysis furnished a sol wherein the kations H' and Na' are inter-14 Chem. Listy, 1925, 19, 195; A., ii, 775.16 Kolloid-Z., 1925, 36, 138; A., ii, 390.16 Rec.trav. cAim., 1925, 44, 103.17 J . Amer. P h m . Assoc., 1925, 14, 10.1* Kolloid-Z., 1925, 36, 328; A., ii, 775.Is H. R. Kruyt and J. Postma, Rec. trav. chim., 1925, 44, 765; A., ii, 861.2O Kolloid-Z., 1925, 36 (Zsigmondy Pmtschr.), 334; A., ii, 621.Considerable attention has been given to silicic acid solsCOLLOID CHEMISTRY. 285changeable. Very concentrated and pure stable sols result fromelectro-dialysis of dilute sols. The number of neutra1 moleculesassociated with a unit charge varied between 320 and 1200.By the oxidation of solutions of ferrous hydrogen carbonateby chlorine water or hypochlorous acid, ferric hydroxide sols areprepared.21 Sols are also produced when ferrous hydrogen car-bonate solutions are ovidised by air or hydrogen peroxide, providedsufficient ferric chloride is present as peptising agent.22 A longpaper by N.Kiihnl and Wo. Pauli23 discusses ferric oxide solsprepared by peptisation of precipitated ferric hydroxide by ferricchloride. The stability and constitution (" ionogenic character ")form the main theme. The same authors 24 deal with the structureof (Al-Fe) oxide sols, or what they term hetero-or mixed-peptides. These are sols obtained by peptisation of precipitatedaluminium hydroxide with ferric chloride, or of precipitated ferrichydroxide with aluminium chloride. Considerable discussion con-cerns the constitution of such sols, a mixed-crystal space latticewith Fe and A1 being suggested for the sol particles, an idea to betested by X-ray analysis.Colloidal bismuth has been prepared by A.Gutbier and T.Kautter 25 by reducing with aqueous sodium hydrosulphite a solu-tion of bismuth nitrate in aqueous glycerol, gum arabic beingpresent as stabiliser. Dialysis and subsequent evaporation on thewater-bath yields a black metallic residue containing up t o 36%of bismuth. From 1 to 2% colloidal sulphur is also included.The product redissolves in water, the particles being negativelycharged.The colloid chemistry of bismuth and its compounds forms thesubject of a detailed investigation in Wo. Ostwalds laboratory.26Various sols were prepared. The metal sol may be obtained byreduction of bismuth tartrate in feebly alkaline solution withsodium hydrosulphite, and the dark brown sol may contain up to3-5 mg.of bismuth per 1 C.C. By the action of hydrogen sulphideon bismuth nitrate solutions containing gum arabic, sols of bismuthsulphide are possible. Using the following concentrations of gumarabic (in %) 0.1, 0-25, 0.5, 1.0, the maximum concentration ofbismuth (in mg. per c.c.) was 0.5, 1, 7, 10, respectively. Colloidalbismuth sulphoiodide (BiSI) was prepared by the reaction betweenthioacetic acid and sodium bismuth iodide in the presence of gum21 G. Stadnikov and N. N. Gavrilov, Kolloid-Z., 1925, 37, 40; A., ii, 861.z2 N. N. Gavrilov, ibid., p. 46; A., ii, 860.28 Koll. Chem. Beihefte, 1925,20, 319 ; A., ii, 776.24 Ibid., p. 338; A., ii, 776.25 2. amrg. Chem., 1925, 146, 166; A., ii, 860.A.Kuhn and H. Pirsch, Koll. Chm. Beihefte, 1925,21, 78286 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.arabic. With this sol many tests were made on the efficiency ofsuch protective colloids as gum arabic, gelatin, and hzemoglobin.I n another paper, Kuhn and Pirsch 27 deal with the peptisation ofbismuth hydroxide and the action of glycerol and sugars as pep-tising agents. Sucrose and mannitol have optimum efficiency in0 -05N-solutions.Colloidal sulphur has been prepared by P. P. von Weimarn andS. Utzino.28 Pure rhombic sulphur (1 gram) is ground intensivelywith 0.9 gram of dextrose in an agate mortar; 0.15 gram is thenenergetically stirred into 100 C.C. of freshly-distilled water. Theauthors' sols contained between 30 @ 20 mg. pcr litre, the meanparticle size being 90 - 80 pp, the particles being negatively charged.The sols were stable for 5 to 10 days.The stability-period of thesols when treated with various electrolytes gave characteristiccurves, stability in days being plotted as ordinates and electrolyteconcentrations as abscissze. Three groups follow from these curves :(1) curves with a maximum (NaCl, CaC12, BaCl,, BaI,, CeCl,, HCl,H,SO,); ( 2 ) curves with two maxima (KCNS, Ca[CNS],); (3)curves with 1x0 maxima (KNO,), i.e., thc stability is always lowerthan in the normal sol. The results are discussed on the assumptionthat adsorption and chemical force are identical in nature, differingbut in degree.29The electrosynthesis of six sulphide hydrosols has been effectedby F.V. von Hahn,3O using molybdenum-, antimony-, lead- andcopper-glance, sphalerite and iron pyrites. The electro-methodswere the cathodic charging (Muller, and Lucas and Le Blanc),luminous arc (Bredig), and oscillating discharge (Svedberg). For thefirst time has been found a critical temperature for the electro-synthesis of metal sols, since molybdenum-glance would not dispersebelow 53".Treatment of a solution of mercuric chloride with hydrogensulphide or soluble sulphide gives a black sol of mercury sulphide,intermediate white and yellow double compounds forming. Theinfluence of excess of either reagent on the condition of the solproduced has been studied by N. I. M o r o ~ o w . ~ ~The photochemical decomposition of arsenic hydride results ina sol of arsenic.32 Bubbling arsine and hydrogen through water inquartz vessels irradiated by a quartz mercury-vapour lamp givesfirst a yellow sol, then red, blue, and bluish-violet sols, the last two2 7 Kolloid-Z., 1925,36 (Zs.igmondy Pestschr.), 310; A., ii, 525.28 Mem.CoLi. Sici. Kycitii Imp. Uniu., 1925, A, 8, 291.29 Compare Kolloid-Z., 1913, 12, 298.Ibid., 1925, 36 (Zsigmondy Festschr.), 277; A., ii, 522.a2 L. Dede and T. Wrtlther, Ber., 1925, 58, 99; A., ii, 197.31 Ibid., p. 21COLLOID CEEMISTRY, 287unstable. The particles are negatively charged, and the red solsare very stable towards electrolytes.Colloidal cobalt hydroxide has been prepared by C. Paal andH. Boeters 33 by alternately adding small amounts of aqueous cobaltchloride and sodium hydroxide to a solution of sodium protalbateor lysalbate.The resulting sol of cobaltous hydroxide oxidisesduring dialysis, especially if hydrogen peroxide is present, formingcobaltic hydroxide sol. Reduction of this solution by hydrogenin the presence of palladium slowly but completely results in ahydrosol of the meta1.34Hydrosols and gels of silver iodide have been described by A.Lottermoser, W. Seifert, and W. F~rstrnann,~~ the work beingbased on the conditions of titration of potassium iodide with silvernitrate.By the reduction of potassium permanganate with sodium arseniteat 65-70", sodium protalbinate being present', a stable brown solof an oxide of manganese was prepared by A. Anargyr~s.~~ Thesol rapidly liberates oxygen from hydrogen peroxide, especially inalkaline solution.Several publications on the dispersion of cellulose in aqueoussalt solutions are due to P.P. von Weimarn,3' but his work is toovoluminous to summarise here. The dispersion of clays is dealtwith by G. Wiegner,38 whose paper is useful for its theoreticalsurvey of the charge on dispersed particles in relation to stabilityand flocculation.Gold Sols.Using methods previously described (Kolloid-Z., 1923, 33, 78)by von Weimarn for preparing gold hydrosols, special attentionbeing given to dilutions and duration of heating, various stablesols are possible by reduction of gold chloride with formaldehyde.Further examination 39 of these sols has been carried out in relationto the factors influencing the size of the metal particles.As theconcentration of reacting solution increases, the average size ofthe crystalline aggregates increases, although the unit crystalsthemselves decrease in size.An important paper on reduction velocity and growth of thea3 Ber., 1925, 58, 1539; A., ii, 1090.34 LOG. cit., 1542; A., ii, 1072.35 Kolloid-Z., 1925, 36 (Zsigmondy Festschr.), 230; A., ii, 514.36 Compt. rend., 1925, 181, 419.37 Kolloid-Z., 1925, 36 (Zsigmondy Festschr.), 103; A., ii, 515; ibid.,p. 338; A., ii, 782; Rep. Imp. Ind. Res. Instit. Osaka, Japan, 1925, 5, 7 ;6, 9.38 KolEoid-Z., 1925, 36 (Zsigmondy Festschr.), 341.Jbid., p. 1; A., ii, 196288 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.particles in the preparation of gold sols has been contributed byR.Zsigmondy and E. Hu~kel.~O Mathematical theory. is supportedby experimental data on the formaldehyde reduction of gold saltseither alone or containing definite quantities of a red gold sol.Rise of temperature, and, to a lesser extent, increase in formaldehydeor the nucleus sol, hastens reduction, this occurring in the immediateneighbourhood of the solid particles.The mobility of the particles in gold hydrosols has been deter-mined by P. A. Thiessen and J. Heumann,41 who find a value of3 x cm./sec. under a potential gradient of 1 volt/cm., thisvalue being independent of the method of preparation, particlesize, and presence of protective colloids. When electrolytes suchas barium chloride and strontium chloride are added, the mobilityis reduced, but coagulation begins before complete discharge of theparticles is effected.L.Fuchs and Wo. Pauli 42 present a lengthy report of their workon the analysis and constitution of colloidal gold. The reportdeals with the Pauli theory of the chemical-complexity and originof charge of colloid particles (Die Zusammenfassung Naturwissen-schaften, 1924, 12, 421, 548) as applied to various gold sols. Thecolloid particles are considered as being covered with a surfacelayer of “ ionogenic gold complex,” the dissociation of which givesrise to the negative charge.in his “ Physico-chemical Studies on Gold Sols,”deals with sols prepared by several methods. Viscosity is namedas the most important factor in colloid systems and the suggestionmade that colloids divide on this basis into two great groups, thegold type and the protein type.Data are given relating to theviscosity and to the catalytic activity towards hydrogen peroxideof gold sols, correlating the results with the degree of dispersion ofthe metal. A Zsigmondy formaldehyde gold sol on ageing orflocculating shows a viscosity which passes through a minimum,but many experiments showed that exposure to light increasesthe viscosity of the sols. The catalytic decomposition of hydrogenperoxide is greater with fresh sols, especially as the alkali contentis increased. Zsigmondy’s “ nuclear ” sols have a catalytic effectdirectly proportional to the degree of dispersion.Gold sols have been used by P.Uhlenbruck44 to follow thedecomposition of protein by pepsin. The change in colour of theA.40 2. physikal. Chem., 1925, 116, 291; A., ii, 775.42 Koll. Chem. Beihefte, 1925, 21, 195.43 KoUoid-Z., 1926, 36 (Zsignaondy Bktschr.), 154; A., ii, 516.44 Ibid., p. 287; A,, i, 742.2. anorg. Chem., 1925, 148, 382; A., ii, 1157COLLOID CHEMISTRY. 289red gold sols runs parallel with the hydrolysis of protein, whilstthe degree to which the flocculated gold is peptised is taken as ameasure of the particle size of the decomposition products. H. A.Krebs45 has shown that gold hydrosols may be precipitated byproteins in two ways: (a) the protein is more acid than a t theisoelectric point, so that the positive colloid is mutually dischargedwith the negative gold ; ( b ) a protein-gold complex may be formed.The protein concentration must be small in the fiTst case, but hasno limits in the second.The reactions are respectively irreversibleand reversible (except in the isoelectric region), whilst the firstgives a blue precipitate and the second a coarse, red precipitate.Organosols.E. Hatschek and P. C. L. Thorne 46 have extended their previouswork on nickel sols in benzene and toluene (compare A., 1923, ii,645, 869), which showed that on heating nickel carbonyl in benzeneor toluene containing rubber sols resulted containing both positiveand negative particles. The pale green precipitate frequentlyobserved in benzene or toluene solutions of nickel carbonyl is dueto oxidation giving a hydrated basic nickel carbonate. In thepresence of 0.17% of rubber such precipitation does not occur,but a green sol ensues, all its particles being positively charged.Further work is required to determine whether organosols in generalcontain oppositely charged ions, and also what is the origin of thecharge.The presence of both positive and negative particles in aplatinum-rubber sol has also been observed by F. ever^.^' Whenthe platinum is flocculated by cataphoresis, it is readily peptisedagain, frequently by simply standing for some hours in the liquid.J. J. Bikerman 4* has prepared sols of arsenic trisulphide in nitro-benzene and in acetoacetic ester. Arsenic trichloride is dissolvedin the organic liquid and dry hydrogen sulphide passed through.A stream of dry air then removes hydrogen chloride and excesshydrogen sulphide.Sols contained up to 29. millimols. of arsenictrisulphide per litre were quite stable, and had a conductivity ofless than lo-' mho. per em. It was shown by cataphoresis teststhat coagulation of the sol results when the electro-kinetic potentialfalls to 25 x 10-3 volt irrespective of the organic medium or thesol dilution. Ferric chloride, copper acetoacetic ester, and tetra-propylammonium iodide were used as coagulants. Bikermanstates that the valence rule apparently holds for organosols ifstrongly ionised salts be used.4 5 Biochem. Z., 1925, 159, 311; A., ii, 1155.46 Kolloid-Z., 1925, 36, 12; A., ii, 197. 4 7 Ibicl., p. 206.REP.-VOL. XXII. KZ . physikal.Chem., 1925, 115, 261; d., ii, 632290 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.According t o F. S. Brown and C. R. nitrobeniene sols ofphosphoric oxide, calcium chloride, silica, alumina, and zinc chlorideare formed in the presence of hydroxyl compounds such as alcoholsor organic acids. The dehydrating agent adsorbs the OH- com-pound, thus becoming peptised. Organosols of grape sugar havebeen described by P. P. von Weimarn.50 A 0.3% solution in acetoneor 1% solution in ethyl alcohol is poured into excess of ether,benzene, tohen?, or xylene, giving violet, deep blue, or green sols.Similarly a chromatic sol (the colour changing with variation intemperature) was obtained by heating glycerol with a solution ofrubber in xylene.A. Kuhn and H.Pirsch 51 prepared colloidal bismuth compoundsin novel fashion. A mixture of the bismuth compound in lanolinwas ground intensively at the temperature of liquid air, givinghighly dispersed systems which could be diluted with sesame oilto form stable sols. In this way the sulphide, sulpho-iodide, andhydroxide sols were obtained containing 12-16 mg. of bismuthmetal per 1 c.c.; 15-20% of lanolin is present as protectivecolloid. Electrical dispersions were also successful in organicmedia.E. W. J. Mardles 52 in a paper on “ The Swelling and Dispersionof Some Colloidal Substances in Ether-Alcohol Mixtures ” treatsof the important phenomenon that characteristic solvent actionappears to be general with a large number of colloidal substancesand mixtures of liquids.Any complete explanation must involvethe significant fact that swelling precedes dispersion. The generalprinciple is stated “ that the characteristic solvent action of mixedliquids cannot be ascribed to the intrinsic action of one kind ofmolecule or molecular complex, but whenever molecular simplific-ation occurs in a liquid mixture there is increased solvent action.”Hence, loss of solvent power ensues when compound formationoccurs between the components of a binary mixture. “Theattraction between a colloidal particle and the molecules of themixed dispersion medium, due to the presence of mutually reactivegroups, appears to reach a maximum with certain combinations ofliquids because of the special spatial arrangement and interlockingof the various molecules in the complex resulting from their size,from the relative strengths of their affinity bonds, etc., so that itis necessary to consider the relative specific characters of the liquidand the colloidal substance.”It) J .Physical Cham., 1925, 29, 1312; A., ii, 1055.51 Koll. Chem. Beihefte, 1925, 21, 78.62 J., 1925, 127, 2940.‘0 Kolloid-Z., 1925, 36, 176COLLOID CHEMISTRY. 291Properties of Colloidal Systems.Investigating arsenious sulphide hydrosol in relation to gravitysettling, A. Dumanski 53 has observed over a period of four yearsa constant fall of the particles, calculated as a uniform rate of 0.031cm. per day. The sol concentration was 0.0651 gram per c.c.,and it stood in a glass tube 1 m.long by 2 cm. in diameter. Thework of Porter and Hedges ( A . , 1923, ii, 743) on the law of dis-tribution of particles in colloidal suspensions was based on theassumption that no contraction or expansion occurs in the form-ation of a dilute suspension of gamboge in water. This assumptionis justifiable according to the experiments made by J. R. H.CouttsY5* who showed by actual density measurements that thesimple additive law holds. W. W. Barkas 55 has shown that theformula used by Porter and Hedges holds within the limit ofexperimental error.Mie’s theory (Ann. Physik, 1908, 25, 378) of the colour of metalsols has been mathematically developed by G. J ~ b s t , ~ ~ who deducesa radiation formula for a sol of completely reflecting spheres dis-persed in a transparent medium.Gold sols were examined, theabsorption and emission spectra being calculated for several solswith gold particles ranging in diameter from 100-600 p.p. Goodagreement with values calculated from Mie’s theory were obtained.The maxima in the curves flatten as the particles increase in size.The curves are correlated with the colours of the sols, the familiarred sol containing the large particles. The absorption curves forsilver hydrosols have been studied by R. Feick, who finds Mie’soriginal theory not in agreement with experiment. Qualitativeagreement with the theory was found when the radiation andabsorption of colloidal mercury were calculated from the data byMeyer (Ann. Physik, 1910, 31, 1017).In a valuable summary, H.Freundlich 57 deals with sols whichcontain non-spherical particles. A vanadium pentoxide sol showsdouble refraction in a magnetic field (Majorana phenomenon),and when stirred, streaks are seen due to dityndallism or doublediffraction, the diffraction of light varying with the orientation ofthe rod-like particles in the liquid medium. The use of the azimuthdiaphragm in the ultra-microscopic examination of such sols isindicated. Closely connected are the experiments of H. Z~cher,~*who observed that when hot concentrated solutions of benzo-53 KoEloid-Z., 1925, 36, 98; A,, ii, 290.54 !Pram. Faraday SOC., 1925, 21, 63; A., ii, 290.55 Ibd., p. 66; A., ii, 289.6 7 Second Colloid Symposium, 1926, 46.68 Z . anorg. Chern., 1925, 147, 91; A., ii, 966.66 Ann.Physik, 1925, ‘76, 863; A., ii, 771.E292 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.purpurin 4B and chrysophenin are cooled, the sols contained long,oriented particles. Brownian motion is maintained as a rapidoscillation about an equilibrium position. When placed in amagnetic field, the sols become anisotropic and reflect polarisedlight.A. Prey 59 contributes a detailed discussion on the double refrac-tion (birefringency) of colloids. It is shown that in a lyophilicsystem of the gelatin type, the disperse phase is present as isotropic,spherical micelles which can be deformed. Crystalline, anisotropicmicelles characterise the lyophobe systems. These two classes ofcolloids differ as regards double refraction, although there isundoubtedly a gradual transition from the more or less emulsoidcolloids like gelatin to the other extreme represented by vanadiumpentoxide sols.The various cases of double refraction are sum-marised as: (i) double refraction due to form, due to orientedanisotropic particles small as compared with the wave-length oflight. They may be parallel, circular cylinders or parallel, oblongrods. These give positivc double refraction. Negative doublerefraction is due to connected lamellae or to parallel plate micelles;(ii) residual double refraction which remains when the doublerefraction due to form is eliminated by using as continuous mediuma liquid with the same refractive index as the particles; (iii) totaldouble refraction, %his being the sum of the two previouslymentioned.It has been shown by H.Freundlich and F. Oppenheimer 6othat on freezing hydrosols, the velocity of crystallisation of thewater is usually increased by the presence of non-spherical disperseparticles, but is increased by the presence of spherical particles.Twenty-two colloid systems (sols, emulsions, suspensions) werecooled to - 3" to - 7" and seeded with ice crystals. The resultsare explained on the theory of orientation of the water moleculesat the surfaces of the disperse particles.E. F. Burton and J. E. Currie 61 have studied the problem of themutual action of charged particles in liquid media, and haverecorded experimental evidence of mutual repulsion producedbetween similarly charged spheres in various liquids.Lead shotdropped through water, alcohol, benzene, toluene, and xylenecarry a negative charge ; through turpentine and carbon disulphidea positive charge, and through ether no charge. The experimentswere applied to the detection of a scattering effect of the shotparticles due to the possession of a charge.58 Koll. chem. Beihefte, 1925, 20, 209; A., ii, 200.6O Ber., 1925,58,143; A., ii, 203.61 Phil. Mag., 1925, 49, 194COLLOID CHEMISTRY. 293Particle Size.Hulet’s well-known observation of the increased conductivity ofa solution of barium sulphate has been repeated by D. Balareff,62who doubts that increase in solubility is to be attributed to thedecrease in grain-size. He suggests that impurities liberated fromthe broken crystals, e.g., barium chloride, may be the cause.The size-frequency analysis of colloidal suspensions and powderscontinues to attract workers, and this subject is already establish-ing itself as an important branch of colloid technique.Its technicalimportance is obvious in relation to clays, soils, pigments, andthe standardisation of manufacturers’ products. An excellentsurvey of the methods available accompanies Sven Oden’s mathe-matical analysis G3 of the grain-size frequency analysis. A biblio-graphy of 41 papers is appended. Another useful summary is thatof J. Parrish,G4 who devotes more attention to elutriation methods.A. Kuhn 65 describes ten methods (applicable to sols) includingthe measurement of light absorption, sedimentation weight,Brownian motion, osmotic pressure, ultrafiltration, dialysis, micro-scope and ultramicroscope enumeration, and X-ray analysis.The Ostwald-von Hahn “ flocculation meter ’’ ( A ., 1924, ii, 262)has been employed by R. Audubert and H. Rabat&,66 W. J. Kelly,67and R. H. Lambert and E. P. Wightman.68 The last authorsdescribe a photographic recorder for following the sedimentationrate. Sedimentation analysis applied to photographic emulsionshas been improved by F. F. Renwick and V. B. Sease. Sediment-ation analysis has been employed in the grain-size analysis ofclays 70 and tungsten powder.71 The frequency curve based onthe photographic study of blood corpuscles has been analysedby E. Ponder and W. G. Millar.72 P. V. von Hahn 73 discussesthe general problem of technical dispersoid-analysis, whilst aninteresting paper by P.Drinker 74 gives details of measuring theparticles of phagocytosed dusts and determining their size-frequencydistribution.63 Soil Sci., 1925, 19, 1.G5 KoEloid-Z., 1925, 37, 365.c2 2. anorg. Chem., 1925, 145, 122; A., ii, 853.64 J. Oil Col. Chem. ASSOC., 1925, 8, 195.Compt. Tend., 1925, 180, 1663; A., ii, 775.67 Second Colloid Symposium, 1925, 29.68 J . Opt. SOC. Amer., 1925, 11, 393.69 Second Colloid Symposium, 1925, 37.70 E. Schramm and E. W. Scripture, jun., J. Amer. Ceram. Soc., 1925, 8,71 K. Agte, H. Schonborn, and K. Schroter, 2. tech. Physik, 1925, 6 , 293.72 Quart. J . Expt. Physiol., 1925, 4, 319.73 Kolloid-Z., 1925, 37, 377; see also F.Hebler, ibid., 1925, 36, 42.74 J . Indust. Hygiene, 1925, 7 , 305.243294 ANNUAL REPORTS ON THE PROURESS OF CHEMISTRY.The globule-size analysis of emulsions has been investigated byA. J. St~mm,~5 using the Ostwald-von Hahn-Kelly sedimentationapparatus modified to deal with systems with a rising disperse phase.The same author collaborated with The Svedberg 76 to determinethe globule-size frequency of emulsions using scattered light. Thescattering of light (in the case of the emulsions studied-benzenein aqueous soaps) varies as the surface or square of the radius ofthe globules. An important paper by The Svedberg 77 concernscentrifuging, diffusion, and sedimentation analysis of colloids andsubstances of high molecular weight. The mathematics of grain-size analysis by means of the ultra-centrifuge is discussed as wellas a new diffusion method.Methods of Research.Recent advances in dark-field illumination have been summarisedby H.Siedent~pf,~~ who describes the theoretical principles andsome new dark- field condensers, including an oil-immersion lenswith an internal iris diaphragm. Another paper on optical techniqueis due to H. Z ~ c h e r , ~ ~ who deals with the general question of aniso-tropy in disperse systems, its detection and measurement.A useful instrument of research is the “ kinoultramicroscope,” acombination of the cinematograph and ultramicroscope. E. 0.Kraemer 8o points out its advantages, such as obtaining a permanentobjective record where, in the ordinary way, quantitative studieswith the ultramicroscope alone frequently involve the use ofstatistical methods.He used the instrument for determining thesize and the size-frequency of particles, investigating gel structureand recording the formation and coagulation of colloid particles.X-Ray methods in colloid research have been dealt with byR. 0. Herzog The former reviews recentwork on the application of X-ray spectrography, particularly inconnexion with the change liquid e solid. Mark describes theexperimental methods employed. X-Ray reflection of fatty acidfilms on glass furnished useful data relating to the molecularorientation of the fatty a~ids.~3The methods in use for determining the electric charge of colloidparticles have been discussed by I€.R. Kruyt 84 in a lucid andand by H. Mark.8275 Second Colloid Symposium, 1925, 70; A., ii, 1153.76 J . Amer. Chem. SOC., 1925, 47, 1582; A., ii, 774.77 Kolloid-Z., 1925, 36 (Zsigmondy Pestschr.), 53; A., ii, 528.78 Ibid., 1925, 37, 327. 79 Ibid., p. 336.Second Colloid Symposium, 1925, 57; A., ii, 1156.Kolloid-Z., 1925, 37, 355. a2 Ibid., p. 351.83 J. J. Trillat, Compt. rend., 1925, 180, 280.84 Kolloid-Z., 1025, 37, 358COLLOID CHEMISTRY. 295well-illustrated paper. The methods include : (1) macroscopiccataphoresis of coloured sols, (2) macroscopic cataphoresis of non-coloured sols, e.g. , Svedberg's ultra-violet fluorescence method,(3) ultramicroscope examination of the cataphoretic velocity ofsingle particles, (4) electric transport.R. Auerbach 85 reviews the methods of diffusion analysis, whilstE.C. Bingham 86 deals with the subject of plasticity in colloidcontrol.Dialysis.The permeability of various membranes for electrolytes has beeninvestigated by L. Michaelis 87 and by A. Fujita,88 both workersfinding, by different methods, that the mobility of anions is muchmore reduced than that of kations. Michaelis enters into thetheory of diffusion in considerable detail. W. Kopaczewski 89 givesthe results of tests on the rate of diffusion of 53 dyes in 1% aqueoussolution a t 25" through a collodion membrane under standardconditions.The use of tap-water in the dialysis of a hydrosol of silica witha parchment dialyser caused the sol to take up calcium, which,however, was easily removed by further dialysis against distilledwater.g0 The results confirm the work of Gutbier, Huber, andSchieber (Chem.Ztg., 1923, 47, 110) that 80% of the electrolytesin a sol may be removed by a first dialysis with tap-water, whichshould be free from iron. The technique of dialysis has beendescribed by H. Rheinboldt .91 The principles underlying dialysisare dealt with and the special apparatus described are the electro-dialyser (Pauli), extraction dialyser (Golodetz) , sealed dialyser(Gutbier and Mayer), vacuum dialyser (Golodetz).Electro-dialysis claims considerable attention in modern work.E. Heymann 92 compares the rate of removal of strong electrolytesfrom sols and finds electrodialysis to be 10 times more rapid thanultrafiltration and 100 times more rapid than ordinary dialysis.L.Kofler and A. Wolkenberg 93 freed various saponins from electro-lytes in this way. E. H. Harveyg4 reduced the ash-content ofagar-agar from 3.75% to 0.81 "/o (dry basis) by electrodialysis, whilst*5 Kolloid-Z., 1926, 37, 379. 86 Second Colloid Symposium, 1925, 106.8 7 J. Gen. Physiol., 1925, 8, 33; A., ii, 1150.8 8 Biochem. Z., 1925, 159, 370; A., ii, 1151.89 Rev. gdn. Mat Col., 1925, 39, 34, 105; A., ii, 529.E. Wilke-Dorfurt and M. Decker, Kolloid-Z., 1925, 36 (2higmondyPeatschr.), 305.91 Ibid., 1925, 37, 387.93 Biochem. z., 1925, 160, 398; A,, i, 1510.84 Amer. J . Pharm., 1925, 97, 66; A . , ii, 293.92 2. physikal. Chern., 1925, 118, 65296 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.W.F. Hoffman and R. A. Gortner 95 found that electrodialysis ofagar-agar for 18 hours removes calcium, but leaves silica andsulphur unchanged.Ultra filtrat ion.A short bibliography and historical survey of the methods usedin ultrafiltration have been given by 13. Rheinboldt .96 Summarisingthe methods and practical importance of ultrafiltration, L. Villa 97recommend’s Bechhold’s impregnation of a porcelain filter withcollodion or gelatin. Using gelatin, to retain colloidal platinumit is necessaryfor the membrane to have a concentration of 2%,for hzmoglobin 4%, and for deutero-albumose 10%. The mechan-ism of ultrafiltration is investigated by J. Duclaux and J. Errera,98who conclude that the membranes employed (nitrocellulose, de-nitrated nitrocellulose, and cellulose acetate) act as bundles ofcapillary tubes.Those liquids having no solvent or softeningaction on the membranes filter a t a rate proportional to theirviscosities. L. Zacharias 99 also discusses the mechanism of ultra-filtration, dealing especially with (I) the support for the mem-brane, ( 2 ) the membrane itself. Using collodion under standardconditions, he found the permeability of the membrane directlyproportional to the porosity of the support. Filtration rate isproportional to the number of layers of collodion deposited. Aliquid which causes the membrane to swell induces opposing effects,the pores open but they also lengthen, so that in some instancescompensation occurs and no extra permeability ensues.Unglazedporcelain carrying barium sulphate in its pores acts as an ultra-filter without the need of a membrane. Swelling or stretching isavoided in such a filter.E. Fouard has devised a collodion ultrafilter capable of stand-ing 40 atm. pressure, the membrane pores having diameters ofthe order 1 pp. Another apparatus designed to yield a uniformmembrane with gelatin or collodion is described by E. Muller.2Stirring speeds up the ultrafiltration of solutions when high pressuresare required, and for this purpose two forms of electromagneticstirrers have been described by B. Bruckner and W. O~erbeck.~A combination of ultrafiltration and electro-dialysis has beenused by H. Bechhold and A. Rosenberg4 to purify gelatin ands5 J .Biol. Chem., 1925, 65, 371; A., ii, 1158.96 Kolloid-Z., 1925, 37, 392.97 Arch. di. Patalog e. Clin. Medica, Sept., 1925, p. 425.95 Rev. gCn. Coll., 1925, 3, 97 ; A., ii, 530.gg Kolloid-Z., 1925, 37, 50.Kolloid-Z., 1925, 37, 237; A., ii, 1061.Ibid., 1925, 36 (Zsiymondy Pestschr.), 192.Biochem. Z., 1925, 157, 85; A., ii, 668.1 Ann. Chirn. Anal., 1925, 7, 33COLLOID CHEMISTRY. 297glue. A modification is the use of the electro-dialyser with anultrafilter at both the anode and kathode, permitting rapid removalof salts. The method has advantages over the usual ultrafiltrationtechnique.5 The probability that the protoplasmic permeabilityof lipoid-insoluble substances is due to an ultra-filtration processis discussed by R. Collander,6 who has also investigated thepermeability of the copper ferrocyanide membrane to acids.An important paper on the ultrafiltration of non-aqueous systemshas been contributed by H.Bechhold and V. Szidon.' By theBechhold-Konig method (2. angew. Chem.., 1924, 494) ultrafiltersfor non-aqueous solutions were prepared (amongst others) byimpregnating porous-clay filters with ether solutions of collodionwhich were then coagulated by benzene or toluene. Oil sols ofzinc and cadmium sulphides, ferric oxide, graphite, and iron andcopper oleate were thus ultrafiltered, as well as a number of dyessoluble in organic liquids. It was shown that the dye solutionscontain only a small portion as colloidally dispersed dye. Theporosity of the ultrafilters was determined by two methods, thesegiving concordant results.The first method is to ultrafilter variouscolloid solutions of known particle size, and the second or " air-bubble method" is based on the maximum pressure required toforce air through the ultrafilter.Viscosity.The work of several investigators on the measurement of theviscosity of colloid systems has been summarised by N. R. Dhar,8whilst the technique of the subject is reviewed by W. S t a ~ f . ~ Wo.Ostwald lo has investigated the velocity function of the viscosityof disperse systems. The deviations of the viscosity of colloidsystems from the Hagen-Poiseuille law are due to factors includedin the general term " structural viscosity," evidence for which isgiven by the variations of pressure or velocity of flow when acapillary viscosimeter is used for measuring viscosity.The velocityfunction of the viscosity of different colloidal solutions may bequantitatively expressed by an extension of the Hagen-Poiseuillelaw of the general form :P n = k p or = k p . t .Here V = the velocity of deformation or of flow (quantityltime),H. Bechhold, Z . Elektrochent., 1925, 31, 496; A., ii, 1158.Koll. Chem. Beihefte, 1925, 20, 273; A., ii, 201. ' Kolloid-Z., 1925, 36 (Zsignzondy Festschr.), 259 ; A., ii, 529.a J . Physical Chem., 1925, 29, 1556.lo Ibid., 1925, 36, 99; 167; 248; A., ii, 291, 392, 663.Kolloid-Z., 1925, 37, 397.K298 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.p = the pressure, t = time, = the total experimentally-deter-mined resistance to deformation (or the viscosity), and k and nare constants. The Ostwald capillary viscosimeter is recommended,but the equation agrees with measurements made with the Hessapparatus to within 1-2%.The Couette apparatus also gives resultswhich fit the equation. Considerable experimental da,ta is recordedand the work of many other workers referred to. R. Auerbach l1describes a capillary viscosimeter for use with a variable velocity offlow. The viscosity of water obeyed the Hagen-Poiseuille law, butly(, gelatin solution did not. The results with gelatin correspondwith the Ostwald exponential equation, provided the pressures areless than about 0.6 m. The change in viscosity with the rate ofshear has been studied by A. de Waele,12 who measured the viscosityof oil sols of mineral earths with a rotation viscosimeter. Theviscosity increased as the rate of rotation was increased.In an interesting account of the determination of viscosity oflyophile colloids, H.R. Kruyt l3 describes a modification of theOstwald viscometer. He found that agar and gelatin sols obeyPoiseuille’s law only when a t a temperature above their gelatinisingpoint. Hydrosols of starch, gum arabic, casein, ceria and silicaobey the law, hut vanadium pentoxide sols on ageing show markeddeviations. It is concluded that sols containing spherical primaryparticles obey Poiseuille’s law, deviations occurring when thespherical form is departed from.E. Hatschek,14 dealing with the variable viscosity of a two-phase system, shows that viscosity may decrease as the rate ofrotation increases owing to the formation of solvent films aroundthe dispersed particles, these films partly breaking down on rapidrotation.Peptisation and Protection.A. V.Slater l5 has classified numerous references to peptisationin an endeavour to return strictly to Graham’s use of the term.The author’s definition is, “ true peptisation is the transformationof a gel to a sol by addition of a small quantity of a dispersing agent.”I n addition to increased electric charge and lowered interfacialtension, a “ true solution pressure ’’ comes into play, the colloidparticles being drawn into solution by the solution pressure exertedby the peptiser. A theory of peptisation is also put forward byl1 Kolloid-Z.(Zsigmondy Futschr.), p. 252; see also K. Matthiius, ibid.,l2 Ibid., p. 332; A., ii, 777.l3 Ibid. (Zsigmondy Featschr.), p. 218; A., ii, 515.Ibid., 1925, 37, 25.J . SOC. Chem. Ind., 1925, 44, 4 9 9 ~ .p. 281 ; A., ii, 663COLLOID CHEMISTRY. 299K. C. Sen,l6 the theory assuming a high degree of adsorption anda suitable concentration of electrolyte. Omitting non-aqueoussystems in which the stability conditions are still obscure, Senbelieves that practically all the known cases of colloid formationin solution can be explained as cases of ion peptisation or peptis-ation by means of an ion-peptised colloid. It is extremely doubtfulwhether non-electrolytes can peptise a substance, and peptisationby an undissociated salt is improbable. The theory is extendedin a further paper 17 and the nature of the protective action raised.Sen believes that protective colloids confer stability owing to aHelmholtz double layer between the colloid particle and themedium.J. Traube and E.Rackwitz l8 have carried out important experi-ments on protective colloids. Protective action is considered torelate to three adhesion forces, viz., between the protective colloidand water, between the initial unprotected colloid and water, andbetween the two colloids. Capillary-active substances possess adecidedly smaller adhesion-force towards water than do the capillary-inactive substances, whence one would expect the protective actionfor hydrophobe sols to be greater with gelatin, albumin, dextrin(capillary-inactive) than with saponin, soap, bile-salts (capillaryactive).Proof of this theory was established by determining the" hydrosol number " after the manner of Zsigmondy's gold number,i.e., determining the amount of protective colloid required toprotect sols of gold, silver, carbon, ferric hydroxide, Prussian blue,sulphur and arsenic trisulphide. It was found that the capillary-active colloids had an essentially smaller protective effect than thecapillary-inactive for hydrophobe sols such as gold, silver, or carbon,but, as anticipated, this difference does not occur for sols of sulphurand arsenic trisulphide, i.e., colloids with a smaller adhesion-forcefor water. Further interesting experimental work supports thetheory.The chemical adsorption theory of protective action finds supportin experiments by S.S. Bhatnagar, M. Prasad and D. C. BahI,l9who measured the surface tension of soap solutions of variousconcentrations with and without such colloids present as arsenic,antimony, and cadmium sulphides. Marked adsorption of soap wasevidenced. Similarly, it has been observed that sugars are adsorbedby the particles in hydrosols of these sulphide sols and seleniummetal hydrosol.20l6 J . Physical Chem., 1925, 29, 1533.l8 Ibid., 1925, 37, 131; A., ii, 968.l9 J . I d . Chem. Soc., 1925, 2, 11; A., ii, 1155.*O J . Physical Chem., 1925, 29, 166; A., ii, 293.Kolloid-Z., 1925, 36, 193; A., ii, 666.a" 300 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The protective effect of gelatin on gold hydrosols varies withthe pH of the solution.H. V. Tartar and J. R. Lorah 21 find pro-tection most marked when the gelatin is a t the isoelectric point orpossesses a negative charge. Below pH 4.7, the gelatin becomespositively charged and its protective power falls rapidly as the p Hdecreases. Between p , 5 and 8 the hydrogen-ion concentration haspractically no influence on the protective action.B. Payaconstantinou 22 has investigated the protective action ofsoaps on gold hydrosols. For 0.1% sodium oleate a t 14" protectiveaction decreased as the size of the gold particle increased. Aseries of soaps was examined, the gold number being determinedat different temperatures. For sodium and potassium laurate,myristate, palmitate, stearate, and oleate, the gold number isreduced as temperature rises, i.e., protective action is enhanced.Sodium and potassium linoleates show the reverse effect.Similarresults have been obtained with arsenious sulphide sol in place ofthe goldW. Reinder~,~4 by determining the gold number of proteins a tvarying pH values, correlates the protective effects with the ampho-teric nature of the proteins. An interesting observation is recordedby A. Boutaric and G. Perreau,25 who protected gamboge suspen-sion by addition of electrolytes in amounts too small to effectfI occulation. If to this protected suspension, electrolyte is furtheradded until flocculation results, the amount of electrolyte requiredfor this effect is greater than is normally the case with an untreatedsuspension. In a later paper,26 a table is given relating t o theprotective action of the chlorides of uni-, bi-, and ter-valent metals,sodium silicate and alkalis on arsenic trisulphide sol against floccu-lation by sulphuric acid and chlorides.Coagulation.It is suggested by A.de G. Rocasolano 27 that the ultramicroscopeobservations of Brownian motion provide a ready means of studyingflocculation changes. A qualitative and quantitative study of theeffect of stirring on the coagulation of hydrophobic sols has beenmade by H. Freundlich and S. K. Basu.2s Copper oxide sol was21 J . Physical. Chem., 1925, 29, 792; A., ii, 864.22 Kolloid-Z., 1925, 36 (Zsigmondy Festschr.), 329; A., ii, 526; J .Physica23 J . Physical Chern., 1925, 29, 323; A , , ii, 393.24 Chem. Weekblad, 1925, 22, 481 ; A., ii, 1059.25 Compt. rend., 1925, 180, 1337.26 Cornpt. rend., 1925, 180, 1841.27 Kolloid-Z., 1925, 36 (Zsigmondy Pestschr.), 80; A., ii, 523.2a Z. physikal. Chem., 1925, 115, 203; d., ii, 522.Chem., 1925, 29, 319; A., ii, 393.Also in Rev. g h . Coll., 1925, 3, 129,167 ; A., ii, 526, 778, 863COLLOID CHEMISTRY. 301used in the quantitative work, the other experiments being donewith sols of arsenic trisulphide, ferric oxide, vanadium pentoxide,and gold. The larger the particles of the sol, the more does stirringfavour coagulation. Its influence is pronounced also when theelectrolyte is in high concentration and when ions of the markedflocculating power are used.These and other experiments of muchinterest support Smoluchowski’s theory of coagulation velocity.The views of L. Michaelis on the “ General Principles of IonEffects in Colloids ” are lucidly summarised in a lengthy paper.29Two effects are recognised : the electrostatic effect, depending onthe valency of the ions and almost entirely due to the ions bearinga charge opposite to that of the colloid. The lyotropic effect, whichis more pronounced with hydrophilic colloids, depends on thewater attracting power of the ions. It does not depend on thecharge sign and only becomes evident in relatively high concen-trations of electrolytes. In contrast to this, the electrostatic effectmay occur in very dilute solutions.According to W.0. Iiermack and W. T. H. Williamson,3° therate of sedimentation of kaolin suspensions under the influence ofvarious salts is markedly affected by variations in hydrogen-ionconcentration. As a rule, the decrease in the pH value favourssedimentation. With sodium chloride, however, sedimentation isincreased by a rise in pH, whereas potassium chloride hastenssedimentation a t all pH values. Chemical actions probably com-plicate the phenomena.In the coagulation of negative and positive colloids by acids andbases, Perrin’s rule ( J . Chim. Phys., 1905,3,50) is that the solutionspossessing equal flocculating power contain the same number ofhydrogen or hydroxyl ions, as the case may be. Notable exceptionsto this rule are recorded by G.Rossi and M. Andreanelli,31 whobelieve the phenomenon cannot be purely electrical.A. B. Weir 32 has investigated the critical concentrations ofhydrochloric, sulphuric, acetic, and citric acids necessary completelyto coagulate a sol of Prussian blue. Citric acid is normal in itsbehaviour, contrary to the results of Bradfield ( J . Amer. Chem.SOC., 1923, 45, 1243). There was no apparent stabilising effect ofthe different anions, a conclusion also reached by Tartar andGailey (ibid., 1922, 44, 2212), who worked with gamboge andmastic suspensions. With oxalic acid, however, a strong protectiveadsorption of the anion is indicated.Considering the mechanism of the adsorption of ions by colloidal29 Second Colloid Symposium, 1925, 1.3O Proc.Roy. SOC. Edin., 1925, 45, 59; A . , ii, 523.31 Qazzetta, 1925, 55, 99; A., ii, 394. s2 J . , 1925, 127, 2245302 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.particles, R. Audubert and M. Quintin33 give evidence for theview that the adsorption equilibrium is fundamentally dependenton electrostatic and osmotic forces and has nothing to do with thenature of the surface or with chemical action between the adsorbentand the adsorbed reagent.W. 0. Kermack and C. I. B. Voge3* have studied the action ofsalts with multivalent kations on hydrosols of gold and gumbenzoin. It was observed that “salts of tervalent kations areable to confer, under appropriate conditions of concentration andpH, a positive change on the particles of a negatively chargedsol.” A zone of precipitation separates the regions wherein thesol particles are negatively and positively charged, respectively.These zones are closely connected with the degree of hydrolysisof the salts.K.C. Sen,35 discussing the antagonistic action of electrolytes oncolloidal solutions, states the general rule that if an ion bearingthe same charge sign as the colloidal particles is more stronglyadsorbed or at certain coqcentrations becomes concentrated a t theinterface between the two phases, then the charge and dispersionof the suspension will be increased. The action of oppositelycharged ions in the system will thus be opposed. If, however,the oppositely charged ion is adsorbed in excess, coagulation occurswith a suspension and phase-reversal with an emulsion.Smoluchowski’s equation of coagulation velocity is confirmed byC.K. Jablczynski and P. Przezdziecka- Jedrzejovska 36 by experi-ments on the coagulation of antimony trisulphide hydrosol withpotassium chloride. Interesting comparison of the conditions ofelectrolyte coagulation of hydrosols of arsenic trisulphide, selenium,and tellurium with Oden’s sulphur hydrosols have been made byJ. J. Do01an.~’ Discussing the many factors influencing sol floccul-ation, the author believes that no general law holds for thequantitative effects of ions.The coagulation of arsenic trisulphide sol by barium chloridepoints to the conclusion, according to A. J. Rabinovits~h,~~ thatthe sol is a fairly strong complex acid dissociating into (As2S,),SHand H’.The coagulation of negatively charged stannic hydroxidehydrosol by means of electrolytes follows the Schulze-Hardy rule,with the exception of thorium nitrate. As the sol concentrationdecreases, the precipitation value of the electrolytes also diminishes.33 Compt. rend., 1925, 180, 513.34 Proc. Roy. Soc. Edin., 1924-1925, 45, 90; A., ii, 523.35 2. anorg. Chem., 1925, 149, 139.36 Bull. Soc. chim., 1925, 37, 608; A., ii, 665.37 J . Physical Chem., 1925, 29, 178; A,, ii, 29338 2. physikal. Chem., 1925, 116, 97; A., ii, 778COLLOID CHEMISTRY. 303Several exceptions to this rule were found and correlated with theadsorption by the sol particles of ions of the same sign. Similarresults were obtained using hydrosols of Prussian blue and ferricoxide.39The influence of adsorbed anions on the coagulation of hydrosolsof arsenic and antimony trisulphides is discussed by S.Ghosh andN. R. Dhar,m whilst K. C. Sen and M. R. Mehrotra 4 l deal with theinfluence of stabilising ions in the coagulation of hydrosols ofchromium hydroxide and copper ferrocyanide. Similar work onion antagonism when mixed electrolytes are used to coagulatearsenic trisulphide sol has been carried out by J. N. Mukherjee andB. N. G h ~ s h . ~ ~ S. Ghosh and N. R. Dhar43 believe that theabnormal behaviour of diluted sols towards coagulation by mixedelectrolytes must be attributed to the adsorption of stabilising ionsof the same sign of charge as the sol.The rate of coagulation of mixed colloids has been investigatedby K.Jabkzyriski and H. Lorentz-Zienko~ska.~~ It was foundthat the velocity of coagulation proceeds according to the same lawas for each sol separately, the experiments being conducted witharsenic and antimony trisulphide hydrosols. It is believed thatcoagulation is a purely physical phenomenon.An interesting case of coagulation has been reported by H. Freund-lich and F. Arsenic trisulphide hydrosol and Carey Lea’ssilver hydrosol when mixed give a colloidal solution which undergoescolour change and shows alterations when studied under the ultra-microscope. The reactions which occur in the light and in thedark are different. The dark reaction most probably depends onthe union of the silver and arsenic trisulphide particles.All theparticles are negatively charged, but, in spite of this, they cometogether owing to a strong chemical affinity. The reaction in lightis purely chemical. and oxygen is a co-operating factor. It is sug-gested that a silver thioarsenite is formed.Sensitisation.The phenomenon of the sensitisation of a colloidal solutiontowards coagulation continues to draw attention. An excellentsummary appeared by H. Freundlich in “ Colloidal Behaviour ”(Bogue), Vol. I, pp. 297-323.3s S . Ghosh and N. R. Dhar, J . Phpical Chem., 1925, 29, 435, 659; A., ii,40 Kolloid-Z., 1925, 36, 129; A,, ii, 386.41 2. anorg. Chem., 1925, 142, 345; d., ii, 665.42 J . Indian SOC. Chem., 1925, I, 213; A., ii, 394.43 J . Physical Chem., 1925, 29, 435; A., ii, 511.44 Bull SOC.chim., 1925,37,612; Rocz. Chem., 1925,5, 178; A., ii, 666,1000.45 Kolloid-Z., 1925, 36, 17; A,, ii, 198.78304 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.W. Beck 46 finds that lecithin or cholesterol added to ferric oxidehydrosol (positive) or molybdenum pentoxide hydrosol (negative)sensitises electrolyte coagulation. Lecithin sensitised Congo-redhydrosol but cholesterol protects this particular sol. G. Ettischand H. Runge 47 dispute Beck's claim that lecithin sensitises Congo-red hydrosol and they also give data showing that globulin is alsowithout effect, although Brossa (KoZZoid-Z., 1923, 32, 107) reportedsensitisation. The discrepancies in the results of various workersin this connexion are due to the salt content and the pH value ofthe systems used.The fact that gelatin may sensitise or protect a hydrosol ofcholesterol depends on the concentration of the gelatin.Accordingto W. 0. Kermack and P. Ma~Callum,~* the protective gelatin layeris unimolecular. When, however, " precipitation takes place, theamount of gelatin present is insufficient to form even a unimolecularlayer, although there is sufficient partially to neutralise the electriccharge on the cholesterol particle." The particles cease to repelone another "and having part a t least of their surfaces bare andcohesive, are precipitated." The experimental work included thedetermination of the cataphoretic P. D. between the cholesterolparticles and the medium in the presence of gelatin at variousconcentrations and a t various pH values.Using a negatively charged copper ferrocyanide hydrosol, K.C.Sen 49 observed that sucrose sensitised its coagulation with bariumchloride, but not with potassium chloride. Ethyl and propylalcohols sensitised the sol towards all coa8gulating ions.A mastic hydrosol is sensitised by sodium chloride towardscoagulation by X-rays, the longer waves having a more pronouncedaction than the shorter waves.5oGelatin.The peculiar position occupied by gelatin in colloid chemistryis reflected in the very active research in many directions. Theinfluence of neutral salts on the combination of gelatin with hydro-chloric, nitric, and sulphuric acids has been studied by J. C~ap6,~1who finds that K'>Na'>Ba">Ca" increases the combination, asdo also Cl', NO,', and 1', but not SO4", this decreasing it. Neutralsalts also influence the swelling of isoelectric gelatin, the Hofmeister4 6 Biochem.Z., 1925, 156, 471; A., ii, 527.4 7 Kolloid-Z., 1925, 37, 26; A., ii, 864.4 8 Proc. Roy. SOC. Ed&., 1924-25, 45, 71; A., ii, 525.49 J . Physical Chem., 1925, 29, 516; A., ii, 664.50 A. Dognon, Compt. rend. SOC. Biol., 1924, 21, 197; A., ii, 665.51 Biochea. Z., 1925, 159, 53; A., ii, 1157COLLOID CHEMISTRY. 305series holding.52 Though the pH has effect on the swelling, theneutral salt action masks this, and Loeb's view that swelling is dueto pH alone is erroneous. The increased dispersion of gelatin byneutral salts is shown by data gathered from ultrafiltration, specificrotation, viscosity, dialysis, gold number, and tannin precipitationtest.% The proteolytic activity of trypsin on gelatin a t 37" isunaffected by the presence of neutral salts, except that N - and 2N-sodium thiocyanate cause a slight decrease.Two papers deal with the surface tension of gelatin solutions.J. H.S. Johnston and G. T. Peard 55 find that rise in temperatureand presence of electrolytes decrease surface tension. Surfacetension data show two maxima, a t p, 4.7 and pH 2.8 to 3.0, minimabeing observed at pH 3.8 to 4.0 and pH 9.0. These result3s are inde-pendently confirmed by L. de Car0,~6 who agrees with Bottazzi andd'Agostino (A., 1913, ii, 115) that the non-dissociated form of thegelatin effects the most marked lowering of surface tension.Instead of the isoelectric point of gelatin being at pH 4.7,I.I. Shukov and S. A. Stschoukarev 57 find the value pH 5.6, andthey assume that gelatin is a mixture of two substances with differentisoelectric points. Several instances occur in the literature showingthat at p, 7-8, gelatin exhibits discontinuity in swelling, lightabsorption, gel strength, and titration curve. E. 0. Kraemer 58examines this problem and believes there is some important changein the system at this pH. His conclusion is that " the second ' iso-electric point ' of gelatin at a pH 7.8 should be due to a neutralisationof the electro-kinetic potential difference with a reversal in signat pH7.8. The discontinuity in swelling and other physical propertiesat this point would therefore reflect the influence of the electro-kinetic potential upon these properties." No second isoelectricpoint at this pncould be found by R.H. Bogue and M. T. O'C0nnell.5~Determinations of the specific rotation of 2% solutions of originallyisoelectric and ash-free gelatin a t 30" at pH values ranging from0-3 to 13.4 showed the specific rotation to vary with p,. Therotation is low at high concentrations of acid or alkali, rising asthe acidity or alkalinity decreases, and exhibiting a minimum valueat the isoelectric point, pH 4.7. A detailed study of the opticalactivity of gelatin systems has been made by E. 0. Kraemer andJ. R. Fanselow,60 who conclude that there is not sufficient evidence52 E. Stiasny and S.R. D. Gupta, Collegium, 1925, 13; A., ii, 392.53 Idem, ibid., 23; A., ii, 393.5 5 Biochem. J., 1925, 19, 281; A., ii, 659.5 6 A t t i R. Acad. Lincei, 1925, 1, 729; A., ii, 857.57 J. Physical Chern., 1925, 29, 285; A., ii, 386.6 8 Ibid., p. 410; A., ii, 519.59 J. Amer. Chem. SOC., 1925, 4'7, 1694; A., ii, 744.6o J. Physical Chem., 1925, 29, 1169; A., ii, 1057.G4 Idem, ibid., 57306 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.for the stat,ement of other workers that gelatin contains two relatedmolecular species. P. Vlhs and E. VellingerY61 investigating therotary power of gelatin a t different pH values (prepared by Loeb’smethod), found the diffusion of light to be a maximum at pH 4.7;two minima occur at pH 2.6 and pH 13. In t,he case of collagen,A.W. Thomas and M. W. Kelly 62 give evidence that two modi-fications exist, “ gel ” and “ sol,” the latter developing in solutionsat 40°, with an isoelectric point at about pH 8.Loeb’s work on the significance of the hydrogen-ion concentrationin the swelling of gelatin has been criticised by Wo. Ostwald,A. Kuhn, and E. Bohme.63 Three different gelatins, includingpure isoelectric gelatin, were examined in relation to swelling asinfluenced by different acids. Concentration and pH value beingmaintained constant, swelling differed in different acids. Theswelling of isoelectric gelatin was influenced in the gradationhydriodic acid>glycerophosphoric acid> sulphosalicylic acid>hydrochloric acid> sulphuric acid. Contrary to Loeb’s view, dibasicacids can exert a greater influence than monobasic acids, in a certainpH range, and the difference between the swelling effects of mono-basic and dibasic acids is always less than that between differentmonobasic acids.In mixtures of salts and acid there is a markedanion effect on the gelatin swelling, the Hofmeister ion series beingfollowed. The swelling of gelatin in aqueous solution is increasedby the presence of formalin, glycerol, phthalic acid, and by mag-nesium and manganese salts, there being an optimum concentrationin each case.64Several workers have investigated the elasticity of gelatin gels.H. J. Poole 65 contributes an important paper characterised by theexperimental technique employed in dealing with jellies.Theauthor concludes : “ The strain produced in gelatin jellies by theapplication of a steady stress is not a function of that stress aloneas in the case of perfectly elastic bodies, but is governed by a timefactor. The results of a study of this time factor or ‘ creep ’ givesupport to the theory that the jellies are two-phase (solid-liquid)bodies. It is shown that the creep is mainly due to a reversibleflow of the liquid phase in the interstices of the solid phase and, toa lesser extent, to an irreversible plastic deformation of the solidphase.” The solid phase is considered to be in the form of a meshof cylindrical fibrils or threads, t,he material of the threads beingin dynamic equilibrium with the water of the liquid phase. The61 Compt.rend., 1925, 180, 439; A., ii, 292.62 J . Amer. Chem. SOC., 1925, 47, 833; A., ii, 520.63 Koll. Chem. Beihefte, 1925, 20, 412; A., ii, 777.64 M. Popov and K. Seisov, Biochem. Z., 1925,156, 97; A., i, 606.65 Tram. Faraday Xoc., 1925, 21, 114; A., ii, 519COLLOID CHEMISTRY. 307ratio of gelatin in the solid phase to that in the liqiiid phase will beprogressively less as the temperature is raised.G. W. Scarth 66 determined the relation of the elasticity ofgelatin to p , by the method of transferring pre-formed gels from amedium of one pH to one of another pH, and comparing the exfensi-bility under a given stress after volume change is more or lesscompleted. The reciprocal of the extension has a minimum valuea t 1 3 ~ 4-7, and maxima at about pH 3 and 11, the latter maximumbeing the higher.Young’s modulus in the case of isotropic gelatinvaries very little between pH 4.7 and pH 11, falling slightly on theacid side of the isoelectric point. Three separate factors affectingelasticity are involved in pH change : (1) direct action of the reagentin combining chemically or by adsorption with the gelatin, (2) themodification of imbibition resulting from such combination,(3) structural changes induced by these effects. Scarth infers thatgelatin gels possess a heterogeneous structure which is modifiedby swelling agents as well as by heat. The major variations in thedegree of swelling must be due to changes in a positive force attractingwater.Details of a method for determining the elasticity of gelatin gelshave been given by E.Sauer and E. Kinkel,67 who find that withpure gelatin the modulus of elasticity varies at the square of theconcentration, but for lower-grade gelatins as the nth power ofthe concentration, n being characteristic for a given gelatin.A series of papers by S. Yumikura deals with the rate of diffusionof capillary active and inactive substances into gelatin gels. 68Previous work by R. Wintgen and H. Lowenthal (Kolloid-Z.,1924, 34, 289) having shown that gelatin and colloidal chromicoxide mutually precipitate each other to an extent depending onthe degree of dispersity and the concentration, the subject has nowbeen extended to the use of iron hydroxide sols, and the conditionsof precipitation have been worked The precipitation ofgelatin by tannin again receives attention.I. A. Smorodincevand A. N. Adova 70 find that pH has a distinct influence. The moreacid the gelatin sol the better is the precipitation. At % 10.06, a0.035% gelatin sol gives no precipitate with tannin. No precipitateforms a t pH 7 if the gelatin is less concentrated than 0.003%, whilsta t % 8.95, a concentration below 0.013% fails to give a precipitate.66 J . Phyaical Chem., 1925, 29, 1009; A., ii, 862.67 2. angew Chem., 1925, 38, 413; A., ii, 519.68 Biochem. Z., 1925, 157, 359, 371, 377, 383; A , , i, 735.69 R. Wintgen and E. Meyer, Kolloid-Z., 1925, 36 (Zsigmondy Featschr.),70 Z . phyaiol. Chem., 1925, 144, 255; A., i, 847.369 ; A., ii, 624308 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.H.B. Stocks and C. V. Greenwood 71 have observed that the carbo-hydrate-tragasol-is precipitated by tannin in similar manner togelatin. It was shown that gelatin films will imbibe solutions oftannin, but do not combine with the tannin.Jellies.P. P. von Weimarn’s views relating to “ the jelly condition ofmatter ” have been confirmed by experiments on disperse systemsof soaps in dry toluene. He regards the formation of a jelly as anextreme case of crystallisation. 72It is a peculiarity of concentrated ferric oxide hydrosols thatwith suitable amounts of electrolytes they set to pasty gels whichliquefy on shaking and re-set again on standing, the time taken inthe second setting being measurable and reproducible. It dependson the anion valency.The kinetics of this sol-gel change formsthe subject of an important paper by H. Freundlich and A. Rosen-tha1,73 the question being: Can one reach a region of constantsetting velocity when increasing electrolyte additions are made toconcentrated ferric oxide hydrosols ? It was found that increasingthe concentration of electrolyte (potassium chloride) did not alterthe value of the setting velocity.E. 0. Kraemer 74 has critically studied the question of thestructure of gelatin gels and concludes that “ gel formation is theresult of an incomplete or unsuccessful attempt at precipitation of asolid phase from a liquid system.” Regarding the micro-structureof the gels and the order of magnitude of the discontinuities withinthem, optical properties and general behaviour indicate a ratherfine-grained structure, but other considerations show that “ on amolecular scale such gels do not possess the high rigidity which theydisplay in bulk.” Cinematograph records were made of theBrownian movement of mercury particles (200-250 pp radius)in the gels, from which the author concludes that the structure ofweak gelatin gels is still considerably finer than the indicatingmercury particles and their displacements. R.H. Bogue 75approves the theory of a fibrillar structure for gelatin gels.Swelling phenomena have been further investigated, methods forthe quantitative estimation of swelling being outlined by P. A.Thie~sen.7~ The kinetics of swelling and shrinkage of gels have71 J .SOC. Leather Trades Chem., 1925, 2, 315; A., i, 1165.72 Kolloid-Z., 1925, 36, 175; A., ii, 390.73 Ibid., 1925, 37, 129; A., ii, 967.74 J . Physical Chem., 1925, 29, 1523.7 5 Ibid., 1925, 29, 1233; A., ii, 1058.7 6 Kolloid-Z., 1925, 37, 406COLLOID CHEMISTRY. 309been studied by I. S. Liepatov 77 and by W. B i l t ~ , ' ~ the latter usingequations based on the conception of lattice energy.E. Hatschek 79 prepared square prisms of gelatin gels, and, aftersetting, these were twisted or bent and so permanently deformed.Subsequent drying increased the deformation. If, however, theinitial gel were set in a twisted form, no further deformation resultedon drying, thus showing that in the former experiments the increaseddeformation was due to the applied sbress on the set gel, and notto its shape.Similar work on the course and character of shrinkinghas been reported by K. SchaumJso who, however, worked withgelatin drops, dried on surfaces such as mercury and glass.B. L. Clarke 81 has presented the general form of the curve relatingswelling capacity of agar-agar gels to the water content immediatelybefore swelling. The curve shows a well-defined maximum. Otherpapers on gels deal with : ( a ) double refraction and dichroism ofstained gels ; 82 (b) diffusion of sodium chloride in agar-agar gels ; 83( c ) coagulation of pectin; 84 (6) gels of calcium hydrate 85 and oftitanic; 86 ( e ) rubber gels; 87 (f) adsorption of acids and alkalis byagar gels.88 The mineral content of the agar is an important factor,especially in the acid adsorption.An interesting paper by E.H. Callow 89 deals with the velocity ofice crystallisation through supercooled gelatin gels (at - 3").Seeding the gels in tubes with ice crystals causes ice to separatedown the tubes a t a uniform velocity, which is less the more con-centrated the gel. Varying the pH with hydrochloric acid leadsto a minimum velocity at the isoelectric point (pH 4.7) and a maximuma t p H 2.6. Other data refer to the effects of neutral salts, and tosalts plus acids, e.g. , addition*of sodium chloride to gelatin-chloridegeIs retards the velocity of crystallisation to a marked extent.Liesegang Izings.WO. OstwaldgO advances a theory of Liesegang rings limited to7 7 Kolloid-Z., 1925, 36, 222; A., ii, 685.79 Ibid., p.202; A., ii, 667.Ibid. (Zsigmondy Pestschr.), 49; A., ii, 520.8o Ibid. (Zs igrtmndy If'estschr . 1, 199.J . Amer. Chem. Soc., 1925,47, 1954; A., ii, 863; compare E. H. Harvey,Amer. J. Phctrrn., 1925, 97, 447; A., ii, 965.82 H. Neubert, KolZ. Chem. Beihefte, 1925, 20, 244; A., ii, 201.83 R. Fricke, 2. Elektrochem., 1925, 31, 430.84 W. Kopaczewski, Bull. SOC. China. biol., 1925, 7, 419; R., i, 872.8 5 Justin-Mueller, Rev. gkn. Coll., 1925, 3, 73.86 S. Klosky and C. Marzano, J . Physical Chem., 1925, 29, 1125.H. Feuchter, Koll. Chem. Beihefte, 1925, 20, 434.J. Effront, Cornpt. rend., 1925, 180, 29; A., ii, 201.Proc. Roy. SOC., 1925, A., 108, 307; A,, ii, 777.Kolloid-Z., 1925, 36 (Zsigmondy Patschr.), 380; A., ii, 530310 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the periodic layers of precipitates in diffusion reactions. His" diffusion-wave theory " is based on two facts : (1) in all reactionsystems furnishing typical periodic layers, there exist a t least threemain diffusion waves.Two run counter to each other, the thirdresults from the union of the first two and advances in both direc-tions ; (2) many, probably all, typical periodic precipitates resultfrom systems belonging, in the sense of the mass-action law, to theso-called limited reactions, L e . , in contrast to such unilateral reac-tions as the precipitation of barium sulphate, they are incomplete.In illustration the following reaction is discussed in detail :[Jelly +Initially the diffusion wave of the external electrolyte (ammoniumhydroxide) into the gel is checked by the formation of magnesiumhydroxide, the concentration of ammonium hydroxide thus beingreduced.The diffusion wave of the internal electrolyte (mag-nesium chloride) advances towards the region of low concentrationof ammonia. Meanwhile the electrolyte ammonium chloride setsup a pronounced diffusion wave in opposite directions from a regionof maximum concentration. A condition is reached where theconcentrations of ammonium hydroxide and magnesium chlorideare so small and that of ammonium chloride so great, that nofurther precipitation of magnesium hydroxide can be formed inthat region. Experimental evidence supports the theory, as, forinstance, the fact that rhythmic precipitates dissolve in excess ofthe reaction electrolyte.Again, if the latter is previously addedto the gel, the resulting strata change in width and in the distanceseparating them.N. R. Dhar and A. C. Chatterjig1 have extended their workrelating to Liesegang rings. Their theory is that peptisation andcoagulation are essential factors in ring formation, the rings beingdue to coagulation of the peptised substance. The coagulum thenadsorbs the same material from its surroundings, thus leaving clearzones. Two classes of Liesegang rings are postulated. I n one theprecipitated layer is followed by a clear layer free from the reactantscausing the precipitate, adsorption of the sol having occurred. I nthe other class the precipitated layer is followed by a clear zonecontaining non-adsorbed peptised substance.The authors discussmany previous investigations by other workers in this field andinterpret their results according to the present theory, which iscapable of explaining the majority.K. Popp 92 has investigated in considerable detail the periodic91 Kolloid-Z., 1925, 37, 2, 89; A., ii, 865, 959.92 Ibid., 1925, 36, 208; A,, ii, 667COLLOID CHEMISTRY. 31 1precipitation of the system : MgCl, + 2NH,OH T+= Mg(OH), +2NH4HC1. The order of the reactants used has no appreciableinfluence on the results, which entirely support Ostwald's wave-diffusion theory. The results are conveniently summarised asfollows :-Decrease inRings. MgC1,. NH,OH.NH,Cl. Gelatin. Temperature.Number. Increase. Decrease. Increase. Constant. Slower form-ation.Width. Increase. Decrease. Increase. Increase. Increase.Distance between. Decrease. Increase. Decrease. Increase. Increase.P. P. von Weimarn's 93 view of the problem is that periodic ringscan result in so many different ways that a single point of viewcannot explain them all. He believes a fundamental factor is theperiodic alteration in the concentration of protective colloid anddisperse phase caused by the precipitate-forming reactantsmeeting.Periodic strata in dilute gelatin gels, with silver nitrate andpotassium dichromate as reactants, are influenced by the age of thegel and by illumination. Most interesting results were obtained byG. W.Scott-Blair.94 The distance to the last Liesegang ring increasedas the gel aged up to ten days, but with further ageing no strataformed. The facts seem t o be connected with a change in the gelstructure. Light of various wave-lengths influences the periodicityof the layers to different extents, the effect being irreversible, sinceif the gel is melted and allowed to re-set, the irregular periodicityof layers persists. Fundamentally distinct from this is the actionof ultra-violet light, which after a few hours' irradiation so affectsthe gel that rings will not form ; melting and re-setting now permitsthe normal Liesegang phenomenon.W. M. Fischer95 bases a theory of the formation of rhythmicprecipitation in gels on the variation of the time of precipitationfrom saturated solutions of salts of different valencies.U-Shapedbands in gelatin gels are described by G. V. Stuckert 96 and a newLiesegang pattern formed by coloured salts in solid gels has beenstudied by E. R. Riegel and L. Widg~ff.~'Rhythmic crystallisation of sodium sulphate in thin agar-agarfilms is influenced by several factors, light increasing the rate andtoo rapid drying causing irregularities. The gel must have a low93 Kolloid-Z., 1925, 37, 78; A., ii, 959.94 Phil. Mag., 1925, 49, 90; A,, ii, 519.95 Z . anorg. Chem., 1925, 145, 311; A , , ii, 853.96 Kolloid-Z., 1925, 37, 238; A,, ii, 1061.J . Physical Chem., 1925, 29, 872; A., ii, 863312 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.agar-agar content, and the salt solution should commence diluteProteins.( 0 .2 5 ~ ) .98A. Blanche-tiere 99 has reviewed the evolution of our knowledgeof the chemical structure of proteins. An extensive paper byW. F. Hoffman and R. A. Gortner 1 gives the results of severalyears’ work on proteins and the results in places radically disagreewith Loeb. The paper is too long for summary here, but thefollowing quotation regarding the isoelectric point is of interest.“ The measured isoelectric ‘ point ’ of a protein probably is not adefinite point but should in all probability be referred to as anisoelectric range. The position of this isoelectric range on thepH scale is dependent on the chemical composition of the protein.The calculated isoelectric point is very near the hydrogen-ionconcentration of neutral water. This is what would be predictedon the theory that a t the higher concentrations of acid and alkalithe binding of acid and alkali follows the adsorption law.Thecalculated isoelectric points are not related to the chemical com-position of the protein.’’believes that the albumins are distinct chemicalindividuals, their amphoteric character being due to the presenceof free amino- and carboxyl groups, and not to the group *CO*NH*.H. R. Kruyt states his reasons for believing the solutions of albuminto be true colloid systems.As pointed out by S. P. L. Sorensen, an important question incolloid chemistry is how far it is possible to apply to protein solu-tions the theories derived from the study of real solutions.I n apaper on the solubility of proteins he records observations on theprecipitation of several proteins and the conditions of their solubilityin water and salt solutions. It is shown that the behaviour ofalbumins when precipitated with ammonium salts does not excludethe application of the phase rule in its usual form and with its usualconsequences. This probably extends to other protein precipitations.Electrolyte-free, water-soluble proteins (glutin, serum-albumin,and ovalbumin) have been obtained by F. Modern and W. Pauliby dialysis followed by electrodialysis The same authors have98 F. 0. Anderegg and G. W. Daubenspeck, Proc. Indiana Acad. Sci., 1925,34, 171.99 BUZZ. SOC. C h i n . biol., 1925, ‘4, 218.I. M. Kolthoff1 Second Colloid Symposium, 1925, 209; A., i, 1479.appears in J .Physical Chem., 1925, 29, 760; A., ii, 1011.8 Ibid., 473; A., ii, 1056.A further paperChem. WeekbZad, 1925, 22, 489; A., ii, 1055.J . Amer. Chem. SOC., 1925, 47, 457; d4., i, 602.Biochem. Z., 1925, 156, 482; A., ii, 518COLLOID CHEMISTRY. 313shown that electrolyte-free blood-albumin and egg-albumin formchlorides with hydrochloric acid, at the same time giving positiveand negative protein ions due to a hitherto unrecognised com-bination of hydrochloric acid with amphoteric ions.The isoelectric points for gliadin and glutenin have been deter-mined by E. L. Tague ' as pH 6.5 and pH 7.0, respectively.Several papers deal with the molecular weight of proteins.L. J. Harris finds the equivalent combining weight of a proteinby adding successive amounts of acid or alkali to the protein andobserving a physical constant of the solution which follows.Acurve relating this constant to the acid or alkali added will havea sharp discontinuity at that point corresponding to the additionof a constant equivalent of acid or alkali. From similar con-siderations, E. J. Cohn, J. L. Hendry and A. M. Prenbiss9 havedetermined the minimal molecular weight of proteins : gelatin10,300, zein 19,400, gliadin 20,700, egg-albumin 33,800, serum-albumin 45,000, casein 192,000. Several other values are alsogiven. From surface tension measurements of very dilute egg-albumin solutions, P. L. du Noiiy lo calculates the upper limit forthe molecular weight as 30,800.Further, he finds iti probable thatthe dimensions of the space occupied by one molecule of crystallineegg-albumin are 30.9 x 30.8 x 41-7 A.U.A review of the coagulation of proteins by heat has been pre-sented by M. Sorensen and 8. P. L. Sorensen.11 Decompositiondoes not accompany such denaturation, unless the heating withhot water is continued. Water is always lost by egg-albuminwhen denaturation occurs, but it is not known whether this loss isa constant. The conclusion reached by H. Wu and D. Y. Wu l2is that denaturation of egg-albumin by heat, acid, or alkali isundoubtedly a hydrolytic process. Exceptional was horse-serum-albumin which, on heating in 0.05 N-hydrochloric acid, was notdenatured.When globulin is heated in water at lOO", its subsequent solu-bility in alkali is reduced to 20y0, in hydrochloric acid to 2.5y0, andin neutral salt solutions to 1% of that of the original protein.M.Adolf l3 discusses in considerable detail the changes so producedby heating globulin.Anal. Asoc. Quim. Argentina, 1925, 23, 93. .J . Amer. Chem. SOC., 1925, 47, 418; A., ii, 391.* Proc. Roy. SOC., 1925, B, 97, 364; A., i, 450.J . Biol. Chem., 1925, 63, 721.lo lbid., 1925, 64, 595; A., ii, 939.i1 Compt. rend. Trav. Lab. Carlaberg, 1925, 15, 1.l2 J . Biol. Chem., 1925, 64, 369; A., i, 1110.l3 Koll. Chem. Beihefte, 1926, 20, 288; A., ii, 199314 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.I n the precipitation of albumin by salts there is an “irregularseries ” or “ tolerance zone.” The first zone of precipitation isobtained with very dilute heavy-metal solutions, the zone of noprecipitation (tolerance zone) being obtained with increasing con-centration of heavy-metal salt.A second zone of precipitation hasbeen shown to be due to denaturing of the albumin. A. W. Thomasand E. R. Norris,l* who have investigated this problem, find thefirst precipitation zone depends on the pH of the solution and thetolerance zone is due to the passage of the solution from the alkalineto the acid side .of the isoelectric point of the protein.Several workers have dealt with casein. According to M. Fischen-ich and M. P~j18nyi,~~ casein ion takes no part in the conductivityof casein solutions. Experiments on the golubility of casein inhydrochloric acid and in mixtures of phosphoric acid and sodiumphosphate lead to the conclusion that casein is a mixture of differentsubstances.Results of Loeb and of Pauli relat.ing to the osmoticpressure, membrane potential, viscosity, and electrical conductivityin alkaline caseinate solutions have been confirmed by K. Kondo.ls0. S. Adair l7 has determined the osmotic pressures of solutionsof various hzemoglobins by a direct method. Rapid equilibrium isattained by a special osmometer and measurements are made a t 0”.H. C. Wilson l8 discusses the increase in osmotic pressure whichresults when haemoglobin is dialysed in an osmometer againstacetic acid, basing his explanation on Donnan’s theory of membraneequilibrium.An important paper on membrane equilibrium has been con-tributed by E.Huckel.19 This treatment is largely mathematicaland concerns an exact thermodynamic theory of membrane equili-brium for ideal and real solutions of completely dissociated elec-trolytes. The Debye theory of electrolytes is applied to themembrane equilibrium of the strong electrolytes and is confirmedby the data of Donnan and Allmand on the system potassiumferrocyanide-potassium chloride.F. Chodat 2o has applied Donnan’s theory of membrane equili-brium to the swelling of gelatin in weak acids. N. Kameyama 21discusses Donnan and Allmand’s results on the membrane equi-librium of potassium chloride against potassium ferrocyanide, froml4 J . Amer. Chem. SOC., 1925, 47, 501; A., i, 603.l5 Kolloid-Z., 1925, 36, 275; A ., ii, 662.l6 Compt. rend. Trav. Lab. Carliberg, 1925, 15, 39; A., ii, 518.l7 Proc. Roy. SOC., 1925, A., 108, 627; A., ii, 965.l8 Biochem. J., 1925, 19, 80; A,, ii, 292.l9 Kolloid-Z., 1925, 36 (Ziigmondy Pestschr.), 204; A., ii, 528.2o Bull. SOC. Chim. biol., 1925, 7, 113; A., ii, 521.21 Phil. Mag., 1926, 50, 849; A., ii, 1062COLLOID CHEMISTRY. 315the point of view of the newer concepts of activity coefficients, andfinds good agreement.A good review of the modern work on proteins and the Donnanequilibrium has been given by D. L. Hitchcock.22 The same author 23has investigated the adsorption of protein from solutions by ~01-lodion discs. The adsorption is a maximum at the isoelectric point.Soap$.Several important papers have appeared from the Bristol labor-atory.McBain 24 in his Royal Institution lecture on " Soaps andthe Theory of Colloids " surveys the work of his laboratory, finallypointing out that the behaviour of the highly complex mixtures ofsaponified oils and fats with various electrolytes met with in soap-boiling can be treated largely on the simple basis of a three-coni-ponent system. Phase-rule models may be employed to follow andpredict quantitatively all the soap-boiling processes. Such acomplete survey has, for the first time, been made of the stablesystems of water, soap and sodium chl0ride.~5 Observations arerecorded upon equilibria in nearly 300 systems containing puresodium palmitate, water, and sodium chloride over a range of tem-perature up to 200" (in sealed tubes).The behaviour of the systemis apparently independent of time. Summarising their work,McBain and Langdon state that in any soap system, whetherprepared from a commercial oil or pure soap, the following phasesexist : true lamellar crystals, crystalline curd fibres, anisotropicliquid " neat soap," anisotropic liquid " middle soap " (existencepreviously unsuspected), isotropic liquid. All the soap-boilingoperations depend on equilibria between these phases. " Thelimits of the field of existence of isotropic liquid solutions of sodiumpalmitate, with and without salt, have been accurately determinedfor temperatures up to 150". This single phase includes whollycrystalloidal and wholly colloidal solutions and ranges a t sufficientlyhigh temperatures from pure water up to pure anhydrous liquidsodium palmitate, the two being miscible in all proportions above316"."W.C. Quick26 confirms previous work showing that the ionicmicelle in soap systems is a hydrated colloidal aggregate of simplefatty ions. I n a solution which is weight normal with regard topotassium chloride and potassium laurate, accurate determinationswere made of the transport of each of the constituents during22 Physiol. Rev., 1925, 4, 505.23 J . Gen. Physiol., 1925, 8, 61; A., ii, 1054.24 Proc. Roy. In&. Gt. Britain, March 20 (1925), 6 pp.25 J. W. McBain and G. M. Langdon, J., 1925,127, 852.2% Ibid., p. 1401316 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.electrolysis.The quantities of potassium, laurate, and chlorideions transported were 0.47, 0-1 9, and 0.32 equivalent, respectively.Only three-fifths of the total current is carried by potassiumchloride, the remaining two-fifths by the ionic micelle. It wasshown that the hydration of potassium laurate in ATw-solution, whereit is entirely neutral (neutral colloid and ionic micelle), amounts to12-8 mols. of w-ater per equivalent of laurate, this confirming thevalue found by McBain and Jenkins by the wholly independentultrafiltration method (J., 1922, 121, 2325).Miss M. E. Laing 27 summarises the work of several investigatorsat Bristol on the unstable states of solutions of sodium behenate.At room temperature a 0.05-0.5 N,-sodium behenate solution isa hard white curd.By special heat-treatment curd formation istemporarily suspended, clear, very mobile liquids ensuing, charac-terised by marked hydrolysis. The largest constituent of theunstable mobile solutions is neutral undissociated soap, the nextlargest being colloidal acid sodium soap with the equivalent quantityof free sodium hydroxide. There is only about 5% of dissociatedsoap.The constitution of the system sodium stearate-water has beeninvestigated by A. von Buzagh,2s who infers that the water in soapgels is held mechanically. Ultrafiltration yields a liquid with aconductivity less than that of the original solution and it is suggestedthat this is due to adsorption of stearate molecules by stearic acidresulting from hydrolysis.Experiments by W.A. Patrick, W. L. Hyden, and E. F. Milau 29show that sodium oleate in ethyl-alcoholic solution is a simpleelectrolyte, being highly ionised at the boiling point in the case ofdilute solutions. Even at high concentrations dissociation occurs.A small amount of water has little, if any, effect upon the dissociation.The change in degree of dispersion of soap solutions when treatedwith uni- and bi-valent metal chlorides is ascribed by R. Minakami 30to ionic antagonism. The coarse-grained structure due to additionof lithium chloride changes to a fine-grained structure when smallamounts of magnesium chloride are added.The viscosity of aqueous soap solutions has attracted severalworkers. N. A. Jajnik and K, S. Malik31 used solutions of puresodium palmitate and stearate, finding that the viscosity variesdirectly as the concentration and inversely as the temperature27 J., 1925,127, 2751.28 Chem.Zentr., 1925, 96, 11, 271.29 J . Phg8icul Chem., 1925, 29, 1004.30 Biochm. 27.. 1925, 158, 306; A., ii, 860.31 Kotloid-Z., 1925, 36, 322; A., ii, 779COLLOID CHEMISTRY. 317The palmitate has the lesser viscosity, but as the concentration andtemperature decrease the viscosities of the two soap solutionsapproach each other ; N/20- and N/Z4-solutions at 60" have almostidentical viscosities. The results are held to support the view ofMcBain on the constitution of soap solutions. From the work ofH. Freundlich and H. J. Kores 32 on the viscosity of soap solutionsit is concluded that solutions of sodium oleate show no elasticity,whilst solutions of sodium stearate only do so in concentratedsolutions.Mixed dilute solutions of these two soaps show a pro-nounced elasticity. The ultramicroscope revea,led long threads inthe mixed solutions, although the initial separate solutions did notcontain them. The threads probably represent a mesomorphousphase. Commenting on this investigation, E. Hatschek 33 drawsattention to the considerable elasticity shown by even dilutesolutions of ammonium oleate.In connexion with the X-ray examination of soaps as thin filmson various metal supports, J. J. Trillat 34 shows that the affinitybetween a metal and fatty acids to form soaps may be gauged bya study of the spectrum intensity produced. The analysis of soapfilms according to Miss M.E. Laing's experiments on bubbles fromsodium oleate solutions, shows the presence of acid sodium soapand not free oleic acid.35Another attempt to standardise a method for comparing thedetergent efficiencies of soaps is based on the observation that whendilute soap solutions are shaken with powdered flake graphite inpresence of air, the appearance of a white band at the lower boundaryof the froth indicates the presence of an excess of soap. Thegraphite is standardised against an ammonium palmitate solutioncontaining sufficient excess of ammonia to insure maximum detergentpower.36Starch.Electrolyte-free starch sols have been obtained by M. same^,^'by heating to 120" and separating into fractions by electro-dialysis.The different fractions give different colours with iodine and havedifferent gold numbers.The molecular weights vary from 90,000to 156,000. It is further shown by Samec 38 that the iodine colourof starch sol components is, within wide limits, independent of the32 Kolloid-Z., 1925, 36, 241; A., ii, 663.33 Ibid., 1925, 37, 25; A., ii, 862.34 Compt. rend., 1925, 180, 1838; A., ii, 752.35 Proc. Roy. SOC., 1925, A , 109, 28; A., ii, 960.36 R. M. Chapin, J. Ind. Eng. Chem., 1925, 17, 461.37 Compt. rend., 1925, 181, 477; A., ii, 1153.30 Koll. Cltem. Beihefte, 1925, 21, 55318 ANNUAL REPORTS ON !CHE PROGRESS OF CHEMISTRY.mean molecular weight. No simple relation could be found con-necting iodine colour and gold number.H.D. Murray 39 has measured the concentrations of the varioussubstances formed when a solution of iodine in carbon tetrachlorideis shaken with an aqueous solution of starch with and without theaddition of small quantities of potassium iodide, From his data hesuggests that starch iodide is an addition compound, the anion ofwhich, in dilute potassium iodide solutions, has the formula(C6H1005)nI'5, where n is approximately 15. Prom his work onthe influence of adsorption on the colour of precipitates, N. R. Dharinfers that it is probable that the blue colour of adsorption com-pounds of iodine with starch, dextrin, cholalic acid, and basiclanthanum acetate is due to the existence of iodine in the colloidalcondition in such compounds.A paper by S.M. Neale *l deals with the elasticity and tensilestrength of starch films, their general behaviour resembling that ofa ductile metal.Capillarity.The thermodynamics of capillary action have been discussed byL. Gay,Q2 who derives the thermodynamic laws of capillarity andinvestigates the restrictions on the phase rule in systems wherecapillaryforces are propounded. Using the equation K = T ~ v ( l +cos 0), where W = adhesion, or work done in separating a solidfrom a liquid, TLT = free surface energy (surface tension) at theliquid-vapour boundary, 8 = angle of contact, N. K. Adam andG. Jessop have investigated the angles of contact and the polarityof solid surfaces. Since W measures the adhesion of solid andliquid, and 2 T ~ y the cohesion of the liquid, the equation shows thatwhen 8 = 0" the solid-liquid attraction is a t least as great as theliquid-liquid attraction ; 8 = 180" indicates no solid-liquid attrac-tion, whilst 8 = 90" shows this adhesion to be half that of the liquidcohesion. From this point of view determinations of 0 against watergive a quantitative guide to the polarity of a solid surface.Theauthors "attempted to use the values of W for solid surfaces oflong-chain aliphatic compounds as an indication of the orientationof the surface molecules. If many polar groups are at the freesurface, the angle of contact should be low; if the surface consistssolely of the hydrocarbon ends of the chain, the angle should beapproximately the same as for paraffin wax." An angle of about39 J., 1925, 127, 1288.40 J.Physical Chrn., 1925,29, 1394.41 J . Text. Imt., 1925, 15, T, 443; A,, ii, 783.42 J . Chim. Phyg., 1925, 22, 116.43 J., 1925, 127, 1863COLLOID CHEMISTRY. 319100" was found for paraffin wax, whether solidified in air or water,or scraped in air; similarly for octadecyl iodide. The nine sub-stances used give results explicable on the authors' theory. In anextension of this w0rk,~4 the " blooming " of varnish films is treatedas an indication of polarity, and the above method compared withthe catalytic activity method of Norrish (J., 1923, 123, 3006).The attractions for water parallel the veiling properties of thevarnishes; if the attraction of water for varnish exceeds 70% ofthat of water for itself, veiling occurs, but there is no veiling whenthe attraction is less than 45-50%.E.K. Carver and F. Hovorka45 have determined the capillaryrise of water and benzene in capillary tubes of glass, copper, silver,and zinc and found the height to be the same in each case, a resultcontradicting the earlier work of Bigelow and Hunter ( J . Physz'caZChem., 1911, 15, 367).Interesting work has been carried out by J. G. Popesco 46 relatingto the capillary properties of mercury. Mercury was formed asdrops in a vacuum and in various gases (0, N, H, CO,, CO, NH,).The surface tension of mercury in a vacuum was determined as436.3 dynes/cm. When mercury drops formed in a vacuum areexposed to gases, the surface tension is less than in a vacuum, anddecreases (towards a limit) with time.Mercury, as drops made ina gas, has a surface tension greater than in a vacuum, but the valuedecreases until in about 24 hours a constant value is reached, lowerthan in a vacuum. Ultra-violet illumination of a negatively chargedmercury drop in a vacuum causes a reduction in surface tension.The results are discussed on the theory of adsorption-orientation(Langmuir, Frenkel, and Harkins).The electrocapillarity of mercury as influented by colloids formsthe subject of an important paper by K. Sandera.47 Kuhera'sdropping-mercury electrode method was used (Ann. Physik, 1903,11,529,698). The surface tension of the dropping-mercury cathode(interface solution/mercury) is greatly influenced by the concentra-tion and the capillary-activity of added colloids, even smallamounts (e.g., 0.001 % gelatin, 0.01 % glycogen, 0.05% gum arabic)of capillary-active colloids sufficing to displace the maximum of theelectro-capillary curve.Arsenious sulphide sol requires a minimumconcentration of 0-5%, ferrous hydroxide sol 0.1 %. Generalising,positive colloids displace the maximum of the electrocapillary curveto the more negative polarising potential, negative colloids to the44 N. K. Adam, R. S. Morrell, and R. G. W. Norrish, ibid., p. 2793.4 6 J . Amer. Chem. SOC., 1925, 47, 1325; A., ii, 647.4 7 Rec. trav. chirn., 1925, 44, 480-7; A., ii, 659.Ann. Physique, 1925, 3, 402; A., ii, 962320 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.positively polarising potential.The results are discussed in con-nexion with adsorption, Helmholz layer, and adsorption potential.K. Schultze 48 has investigated the connexion between capillarityand evaporation and efflorescence. For true (circular) capillariesthe evaporation of water is independent of the cross-sectional area,but is greater the nearer the meniscus approaches the end of thecapillary. As the dist’ance between the meniscus and the endincreases, the evaporation rapidly slows down. The slope of thecapillary is without influence provided there is no change in theposition of the meniscus. I n the case of “ mixed” capillaries(irregular cross-section) evaporation depends on the cross-sectionand the form of the meniscus. Such conditions are present in evapor-ation from granular and porous materials.The work has beenextended to a consideration of the relation between capillarityand wetting.49The extent to which surface forces influence the wetting of yarnduring sizing is examined by F. D. Farrow and S. RT. Neale,so theirdata including surface tensions of solutions of starches, sodiumoleate, cyclohexanol, and Turkey-red oil, as well as interfacial tensionof these solutions against paraffin and castor oil.W. Bachmann and C. Brieger 51 find a connexion between theheat of wetting of lubricating oils and metal (pure copper). Thebetter lubricating oils had the higher heats of wetting, and inagreement with this is the observation that a small addition ofunsaturated acid such as oleic, to a petroleum oil produced a rela-tively large increase in the heat of wetting.Such a mixture hasbeen found by Southcornbe and Wells (J. SOC. Chem, Ind., 1920,39, 5 1 ~ ) to have enhanced lubricating efficiency.W. Kopaczewski 52 has investigated the electrocapillary analysisof natural and synthetic dye sols using strips of filter-paper. Electro-negative dyes ascend to the same height as water, colouring theupper edge of the paper more deeply, whilst electropositive dyes risebut little, staining being pronounced a t the liquid contact. Ampho-teric dyes form bands of light and deep colour, whilst colloids of lowsurface tension show good ascension independent of the electriccharge.Xurface Tension.Considerations based on the Eotvos expression ( d A /dT) VmY3 =constant, where A = capillary constant of a liquid, V , = molecular4’ Kolloid-Z., 1925, 36, 65-78.4’ Kolloid-Z., 1925, 377 10.50 J .Text. Inst., 1925, 16, 209 T.61 Kolloid-Z., 1925, 36 (Z8igrnondy 3’errtsc?w.), 142; A., ii, 510.ompt. rend., 1925, 180, 1530; A., ii, 828COLLOID CHEMISTRY. 321volume, have led Brillouin 53 to the conclusion that the moleculesin the surface layer of a liquid are about as far apart as are themolecules in the interior of the liquid. The molecular significanceof surface tension has been discussed by N. K. Adam and G. Jessop 54on the basis of experiments on the development of streamers a t theinterface of two liquids during mixing. Very interesting workhas been carried out on a large number of liquids by C.V. Ramanand L. A. Ramdas 55 relating to the connexion between the scatter-ing of light a t liquid surfaces and surface tension. Lowering of thesurface tension, or increase in refractive index, is accompanied bya more intense surface opalescence. Thus, when oleic acid spreadson water in quantity just sufficient to prevent camphor movements,the surface opalescence is about twice as great. Addition of furtheroleic acid results in an enormous increase in surface films. In thiscase, a discontinuous surface results, due to minute globules ofoleic acid.S. Sugden 56 has dealt with the mathematics underlying the deter-mination of the surface tension of a liquid by the method of rise incapillary tubes.When water drops into the saturated vapours of carbon tetra-chloride, light petroleum, toluene, benzene, chloroform, triethyl-amine, and ethyl ether, the surface activity of these vapoursinfluences the surface tension of the water to an extent parallelwith the interfacial activity of the corresponding organic liquidson water.57 The effect of capillary-active substances on the surfacetension of salt solutions has been investigated by W.Seith.58Solutions of methyl, isopropyl, isobutyl, and isoamyl alcohols, andof aniline, in pure water at various concentrations were treated withsolutions of salts such as the chlorides of sodium, potassium, lithium,magnesium, and barium, also magnesium sulphate and urea, andthe surface tensions determined by the method of Stocker (Z.physikal.Chern., 1920, 94, 149). The surface tension lowering dueto the presence of the capillary-active alcohols is intensified by thepresence of the salts, the effect increasing with the salt concentra-tion. Curves relating surface tension to quantity of capillary-active solute give, for the systems containing different concentra-tions of salts, a family of curves cutting in one point. Ionic hydra-tion is considered the underlying cause of the salt effect. The degree53 Compt. rend., 1925, 180, 1248; A., ii, 496.K4 Proc. Roy. SOC., 1925, A , 108, 324; A,, ii, 772.65 Ibid., 109, 150, 272; A., ii, 952, 1046.66 J . Amer. Chem. SOC., 1925, 4'9, 60.57 V. Korh, Rec. trav. chim., 1925, 44, 460; A., ii, 659.s8 2. phy8ikaE. Chem., 1925, 117, 257; A., ii, 961.REP.-VOL.XXII. 322 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of hydration of the ions may be calculated from the lowering ofsurface tension produced.R. G. Schulz deals with the distribution of surface-activesubstances between water and organic solvents, and W. D. Rarkinsand H. M. McLaughlin 6o consider unimolecular film formationbetween liquids. The number and disposition of molecules in unitarea are considered from the standpoint of molecular dimensionsand the theory of orientation.The lowest surface tension so far found for a dilute aqueoussolution is that of 0.1 M-sodium nonoate, the value being 20.2dynes/cm. a t 20". Addition of sodium hydroxide sufficient to makethis solution 0.005 M with respect to the base increases the surfacetension to 45.4 dynes/cm., and at 0.008 JI to 4843 dynes/cm.There-after additions of sodium hydroxide decrease the surface tensionlinearly. The explanation given 61 is that the extremely lowsurface tension is due to a surface film of sodium nonoate andnonoic acid resulting from hydrolysis. Sodium hydroxide, byrepressing hydrolysis, raises the surface tension due to removal ofthe acid, further sodium hydroxide then increasing the activity ofsodium nonoate in the solution and also its concentration in thefilm, thereby lowering surface tension.The surface tensions of the two liquid phases formed by waterand phenol at different temperatures have been determined byA. K. Goard and E. K. Rideal.62 The difference between thesurface tensions of the two phases diminishes regularly up to thecritical solution temperature, and no " inversion point " a t 40" to45" was found.Greater miecibility of the liquids is accompaniedby a decreasing difference in the surface tension of the phases. Itwas found that the phase richer in the low-tension component hadthe higher surface tension. For determining the interfacial tensionbetween two liquids, P. L. du Nouy 63 recommends the well-knownplatinum ring tensimeter, the tension being measured directly indynes from the force required to drag the ring from the dinericinterface.Wo. Ostwald and A. Steiner 64 have published an interestingpaper on the inter-connexion of surface tension and frothingcapacity. Low surface tension of a liquid is, of itself, not sufficientto confer the ,capacity to foam. Liquids of quite high surface5 9 Koll.Chem. Beihefte, 1925, 21, 37; A., ii, 956.Go J. Amer. Chem. SOC., 1925, 47, 1610; A., ii, 771.6 1 W. D. Harkins and G. L. Clark, ibid., p. 1854; A., ii, 857.63 J., 1925, 127, 780.6a Cornpt. rend., 1925, 180, 1579; A., ii, 647.Kolloid-Z., 1925, 36, 342; A., ii, 771COLLOID CHEMISTRY. 323tension can foam, and in some cases reduction of surface tensioncan destroy foaming.Useful data relating the surface tension of wort and beers tothe colloid constituents and pE values have been presented byG. T. Peard and J. H. St. Johnston,G5 their work bearing directlyon the problem of frothing. A similar communication is due toJ. King.66Interface Ph)enornena.Of the many phases of colloid research one of the most importanttheoretically, and one which is attracting increasing attention,concerns the phenomena of concentration gradient at interfaces,chiefly the air-liquid interface.Numerous papers have appearedduring the year dealing with surface concentration, molecularstructure of surface films, orientation, and surface energy.A general discussion from the point of view of thermodynamicsdeals with the effect of surface energy on colloidal equilibri~rn.~’The free energy of a surface is considered to consist of that energycovered by the ordinary concept of surface tension and also acertain free energy due to a potential difference between the surfaceof a particle and the surrounding liquid. The discussion deals withchanges in surfaces in relation to area only, not to thickness ordensity.Two interesting reviews deal with “ Chemistry at Inter-faces ” (W. B. Hardy) 6 8 and “ The Structure of Surface Films onWater” (N. K. Adam).69The Gibbs adsorption equation has been deduced thermodynamic-ally by M. Vo1merJ70 whilst A. Frumkin 71 gives a simple method forthe proof of the Gibbs equation. Addition in drops of solution oflauric acid in light petroleum to water causes the surface tensionof the water to decrease as the ether evaporates. As soon as thesurface layer is “saturated” with lauric acid a further drop ofetheral solution but slowly disappears. The time required to reachthis condition is definite and reproducible. Frumkin in this wayfound the “ saturation capacity ” of the water surface to be 5.2 xmol. of lauric acid per sq.cm. Now connecting the surfacetension depression of water containing lauric acid in solution withconcentration, the quantity - du/d log C may be calculated graphi-cally. Frumkin found for this quantity 13-9, whence Gibbs’s6 5 J . Imt. Brewing, 1925, 31, 416.e6 Ibid., p. 32.6 7 H. 0. Halvorson and R. G. Green, Second Colloid Symposium, 1025, 185,J., 1925, 127, 1207.J. Physical Ghem., 1925, 29, 87; A., ii, 195.70 Z. physikal. Chem., 1925, 115, 253; A,, ii, 539.7l Ibid., 1926, 116, 498; A., ii, 866.L324 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.equation, - (l/RT)du/E log C, gives 5-7 x 10-10 mol. of lauric acidper sq. cm.Frumkin 72 has also considered the distribution of a substancebetween two phases, connecting the partition coefficient with thework done in transferring one mole of the substance from onephase to the other.His considerations when applied to the dis-tribution between internal liquid and surface layer, lead to Traube’srule for the increase in adsorbability in homologous series.A comprehensive review of work concerning the P.D.’s andelectrical charges arising at a liquid-gas irterface has been publishedby H. W. Gilbert and P. E. Shaw,73 who add a bibliography. Theelectrical properties of unimolecular films of adsorbed insolublesubstances have been investigated by A. Pr~mkin,’~ who measuredthe P.D. at the interface air-adsorbed film. The observed effectsin the case of the higher members of homologous series can beexplained on the basis of Langmuir’s orientation theories, but theeffect per mole is less than in the case of the lower members of theseries.R.K. Schofield and E. K. Rideal 75 have examined the surfacetension-concentration curves for aqueous solution of severalcapillary-active organic substances. It is believed that themolecules of these capillary-active substances are adsorbed froma dilute solution in a unimolecular layer and ‘( that the effect theyproduce on the surface tension is due to their thermal agitationalone. At a given temperature their effectiveness depends solelyon their surf ace concentration, their interfacial areas and theirlateral cohesion.” A critical examination is made of Traube’sviews on surface tension in relation to osmotic pressure, and amodified equation is reached : P(A - B) = xRT, analogous to thatof Amagat connecting the pressure and volume of highly compressedgases.Here P = surface tension, A = area occupied by a gram-mole of the active substance at the interface, B = limiting area ofa gram-mole under high compression, and l/x = measure of thelateral molecular cohesion. The equation accords with data forwater-air, water-benzene, and water-mercury interfaces.A. Cary and E. K. Rideal 76 have dealt in three papers with thebehaviour of crystals and lenses of fat on the surface of water.‘( In an experimental study of the process of surface spreading onwater and solutions of 0.01 N-hydrochloric acid of organic com-pounds containing a long chain terminating in a polar group,The agreement in the two results is excellent.72 2.phyaikal. Chern., 1925, 116, 501; A., ii, 866.73 Proc. Phys. SOC. (London), 1925, 37, 195; A., ii, 795.74 8. physikal. Chern., 1925,116, 485; A., ii, 873.7 5 Proc. Roy. Soc., 1926, A, 109, 57; A., ii, 960.7 O lbid., pp. 301, 318, 331; A*, ii, 1046, 1847, 1048COLLOID CHEMISTRY. 326including acids, esters, ethers, phenols and nitriles, it is foundthat unimolecular films spread from crystals as well as lenses, adefinite equilibrium surface tension or two-dimensional pressurecharacteristic of the substance in question being established.”When an oil film spreads, this is due to the pushing effect of incomingmolecules (from the lens or crystal) rather than the attractive pullof the uncontaminated water.The second paper deals with theeffect of temperature on the pressure of a film in equilibrium witha crystal or lens of various organic long-chain compounds ending inpolar groups. Highly insoluble solid compounds do not affect thesurface tension of water below a certain definite temperature,above which, until the melting point is reached, surface tensiondecreases linearly with temperature rise. A sudden change in theslope of the curve occurs at the melting point, but the linear relationcontinues to hold. Exceptions were noted and an explanationwas advanced. The third communication concerns the effect ofthe polar group on the equilibrium pressure.Although furtherexperimental work is necessary, it seems that the slope of thesurface-tension curve up to the melting point is determined by thehydrocarbon chain, and thereafter the polar group is the importantfactor.From very accurate measurements of the surface tensions ofsodium chloride solutions from 0.1 to 5M, W. D. Harkins andH. M. McLaughlin71 deduce that the apparent thickness of thewater film on a solution of sodium chloride is 4 A.U. at a concen-tration of 0.1 M , falling to 2.3 B.U. a t 5N. The thickness is, there-fore, of the order of a linear dimension of a water molecule and itis suggested that the ions in the solutions “ keep buried beneath amonomolecular film of water. As the concentration of salt increases,the diffusion pressure forces the ions closer and closer to the surface.”Several papers deal with unimolecular films in various connexions,prominent being those by P.L. du N0iiy,78 J. F. C~~rrihre,~~ andW. D. Harkins and J. W. Morgan.80 Studies of surface concentra-tion comprise several contributions. J. M. Johlin 81 determinedthe surface tension of ash-free isoelectric gelatin a t 40” at the air-liquid boundary for various concentrations of aqueous solution,the change in surface tension being noted with the increasing ageof the interface. The change in surface tension with time takesplace according to the equation cr = a/tn, where u = surface tension,7 7 J . Amer. Chem. Soc., 1925, 47, 2083; A., ii, 959.713 J . phy8. Radium, 1925, 6, 145; A., ii, 844; J .Expt. Med., 1925, 41, 663.70 Rec. trav. chirn., 1925, 44, 121 ; A., ii, 287.*1 J . Phyaical Chem., 1925, 29, 271, 1129; A,, ii, 388, 1054.Proc. Nat. Acad. Sci., 1926, 11, 637; A., ii, 1148326 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.t = time, a and n constants. The relation holds well for dilutesolutions over a considerable period of time. Johlin found theequation also valid in the case of sodium oleate solutions of 1 to0.0001% concentration. It also held for colloidal sulphur, and nosatisfactory explanation is as yet advanced as to why this shouldbe so. The same equation expresses the rate of surface concentra-tion of casein, crystalline egg-albumin, and crystalline hemoglobin. 82E. Keiser 83 finds that cholesterol and its esters decrease thesurface tension of water.The surface activity of the esters fallsoff as the number of carbon atoms in the acids increases. J. B.Leathes 84 produces striking photographic evidence for the orient-ation of molecules a t the interface between cholesterol and water(and aqueous solutions).An important paper by A. Frumkin 85 gi,ves the surface tensioncurves of the higher fatty acids together with an equation for thecondition of the surface layer. The curves relate to solutions ofcaprylic, caproic and lauric acids, Wilhemy’s method being used.It is shown that the deviation in form of the curves from thoseshown by the lower fatty acids is explicable on the effect of attrac-tive forces and (finally) condensation phenomena in the adsorbedlayer.The equation of Szyszkowski (2. physikal. Chern., 1908,64,385) may be modified to include a term depending on the mutualattraction of the adsorbed molecules, and it will then satisfy theobserved data.A. K. Goard and E. I<. Rideal86 raise the interesting question asto whether the presence of a unimolecular adsorbed film of oriented(phenol) molecules at a water surface solely determines the surfacetension. Their results indicate that molecules at greater depthsalso have an influence upon it. “ A complete theory of surfacetension should cover both the surface film and the ‘ foundation ’upon which that film rests.”Adsorption.A general review of the theories of adsorption is given in a paperby L. Abonnenc. 87 The various adsorption equations proposedby Langmuir, A.M. Williams, Freundlich and others have beendiscussed by A. Gorbatschev,s8 his investigations dealing with thedensity of the lines of force at the adsorbing surface.LOC. cit., p. 897.83 Biochem. Z., 1925, 154, 321.84 The Lancet, 1925, 853, 958, 1019.8 5 2. physikal. Chem., 1925, 116, 466; A., ii, 856.8u J., 1925, 127, 1668.Rev. gkn. Sci., 1925, 36, 262.2. physikal. Chem., 1925, 117, 129; A., ii, 959COLLOID CHEMISTRY. 327Wo. Ostwald and H. Schulze 89 have shown that the adsorptioncurve obtained when (Co - C) is plotted against C has an S-formif the curve includes C = Here Co = initial per-centage of solute in solution, and C = percentage of solute in solutionwhen adsorption is complete. Simultaneous adsorption of solventas well as solute must be accounted for.The paper is an importantcontribution to adsorption problems and should be read in con-junction with another discussion on the S-curve, given by K. W.E’lor~v.~~ M. P6lAnyi 91 has derived an equation connectingadsorption with swelling pressure and osmotic pressure. It isargued by B. Iljin92 that adsorption is not a specific phenomenon.Assuming a purely electrical origin for adsorption forces, he derivesan equation connecting the heat of adsorption and adsorptioncapacity with the dielectric constant and surface energy of theadsorbent .93Adsorption from Gases.-W. D. Bancroft 94 has written a generaldiscussion of the work done by various investigators on electri-fication in relation to the removal of adsorbed gas films.Anexperimental investigation of the dynamical equation of the processof gas adsorption was undertaken by D. H. Bangham and W. Sever,95who confirm the equation of d log s/d log t = constant (llm) for theearly stages of the process of sorption on glass surfaces. Heres = quantity of gas adsorbed in time t . For time-sorption databeyond the range of obedience to the first equation, the equationlog C/(U--- s ) = ktl’m holds, c being the limiting values of s as tapproaches infinity.B. Iljin 96 derives formulze for calculating the extent of adsorbingsurfaces. Three different methods give the adsorbing surface of1 gram of charcoal as being of the order lo5 sq. em. It is provedthat for equal values of the heat of adsorption the quantities of gasadsorbed per sq.cm. of different surfaces (carbon and mica) are thesame. The surface energy of an adsorbent is a measure of itsadsorption activity.W. A. Patrick and his collaborators have published several import-ant papers on adsorption. Previous work by Patrick on the relationof capillarity to adsorption is reviewed, particularly in relation tosilica gel experiment^.^^ Accurate measurements have been madeand C = 100.Kolloid-Z., 1925, 36, 289; A., ii, 657. Ibid., p. 215; A., ii, 657.s1 2. physikal. Chem., 1925, 114, 387; A., ii, 290.Q2 2. Physik, 1925, 33, 435; A., ii, 958; Physikal. Z., 1925, 14, 497ss Phil. Mag., 1925, [vi], 60, 1144; A., ii, 1149.94 J . Physical Chem., 1925, 29, 20.B6 Phil.Mag., 1925, [vi], 49, 935; A , , ii, 507.s6 2. physikal. Chem., 1925, 116, 431; A., ii, 856.97 Kolloid-Z., 1925, 36 (Zsiqmondy Festschr.), 272; A., ii, 509328 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of the adsorption of carbon dioxide and nitrous oxide by silica gelat O", ZOO, 30°, and 40", at pressures below one atm~sphere.~~ Theresults point to the fact that the liquid in the capillaries at tem-peratures near the critical temperature exhibits an increase insurface tension due to capillary forces. The critical temperatureis raised in the pores of the adsorbent. In another investigati~n,~~a dynamic method was used to follow the adsorption of vapours ofalcohol, carbon tetrachloride, benzene, and water by silica gel.With the exception of water, excellent agreement was found withthe equation V = K(Pa/Po)1In, based on the capillary theory ofadsorption. Here P = the partial pressure at equilibrium of thevapour adsorbed, Po = the saturation pressure at the temperature,CT = surface tension, V = C.C.of vapour adsorbed per gram of gel.K and l/n are constants depending only on the gel structure.Water shows anomalous behaviour due to increased viscosity ofthe adsorbed water, the internal pressure having been decreased bycapillary and surface tension forces. Further support of thecapillary adsorption theory is given by data concerning the adsorptionof butane by silica gel.1Patrick and C. E. Greider have measured the heats of adsorptionof sulphur dioxide and water vapour by silica gel at 0".In eachcase the difference between the heat of adsorption and the heat ofliquefaction is explained on the basis of surface energy consider-ations. R. C. Ray3 has determined the adsorption of nitrogenperoxide by silica gel at different temperatures and pressures,Freundlich's empirical equation holds for all the cases investigated.except when the saturation pressures were approached. Withincertain limits, the water content of the gel exerts no influence onthe amount of adsorption.Various investigators have employed glass as the adsorbingsurface. D'Huart * studied the adsorption of water vapour,alcohol, chloroform, benzene and toluene vapours. The wateradsorbed varies as the surface area of the glass and as the vapourpressure.The organic vapours were adsorbed but to a very smalldegree. The rate of sorption of ammonia by a glass surface a t 0"was measured a t various pressures by D. H. Bangham and F. P.The results at all pressures and times over the experimentalrange accorded with the equation S~ = kp& p . dt, where s = thesorption value at time t, pt = the momentary pressure, and ~ Y L iss8 J . Physical Chem., 1925, 29, 421; A., ii, 508.99 W. A. Patrick and L. H. Opdycke, ibid., p. 601; A., ii, 656.1 W. A. Patrick and J. S. Long, ibid., p. 336; A , , ii, 382.2 Ibid., p. 1031.6 J. Physical Ghem., 1925, 29, 113; A., ii, 284.Ibid., p. 7 4 .Compt. Tend., 1925, 180, 1594; A., ii, 657COLLOID CHEMISTRY. 329approximately constant (about 12). In the case of carbon dioxide,analogous results were obtained, but m varied with the pressure,t o which the sorption value was much more sensitive. “ While forstrictly constant pressure experiments with ammonia it was con-cluded that logs would be a (nearly) linear function of log (p2t),for carbon dioxide, under the same conditions, logs would be a(non-linear) function of log (p5t).” Similar work has been doneby these authors, using nitrous oxide and sulphur dioxide.6E.Moles and R. Miravalles 7 believe that in the adsorption ofhydriodic acid by glass, capillary condensation may occur, and thatin addition to true adsorption chemical reaction between the acidand glass can take place. I. R. McHaffie and S. Lenher * studiedthe films of water adsorbed from the gas phase on plane glass andplatinum surfaces when the pressure of the water vapour was nearthe saturation value.Their method directly measures the numberof molecules adsorbed from a saturated vapour on a known area ofa plane surface. The adsorption was calculated from measurementsof the decrease in pressure in the system when passing from tem-peratures at which all the water present was in the gas state (anda t pressures proportional to the absolute temperature) to tem-peratures where the entire mass of water was in the vapour state(and the pressures equalled the vapour pressure of the water a tthe corresponding temperature). Adsorption began a t a finitepressure and was reversible. The glass adsorbed much more thandid platinum. cm.in thickness for glass, and 0 to 1.13 xNumerous papers deal with charcoal as an adsorbent for gases.The whole subject is reviewed by I.L. Ab~nnenc.~ The questionof the adsorptive power of charcoal in relation to activation is con-sidered by H. Herbst,lo 0. Ruff and E. Hohlfeld,ll F. Konig l2and H. H. Lowry and S. 0. Morgan.13 The difference between theadsorptive power of charcoal before and after compression has beendealt with by E. Urbain,14 who goes into the question of porosityin relation to gas adsorption. Hydrogen activates graphite as asorbent for oxygen, but has no influence on the adsorption for carbondioxide.15The adsorbed film varied from 0 to 5.3 xem. for plat,inum.6 D. H. Bangham and E. P. Burt, ibid., p. 540; A., ii, 657,7 Anal.Fig. Quim., 1925, 23, 223.B Rev. gdn. Sci., 1925, 36.11 Kolloid-Z., 1925, 36, 23; A., ii, 192.12 Pharrn. Zentr., 1925, 66, 645; A., ii, 1054.13 J. Physical Chem., 1925, 29, 1105.14 Compt. rend., 1925, 180, 63; A., ii, 191.15 D. H. Bangham and J. Stafford, J., 1925, 12’7, 1086.J., 1925, 127, 1559.See also W. Mecklenburg, 2. angew. Chem.,1925, 37, 873. lo Koll. Chem. Beihefte, 1925, 21, 1.L330 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The use of charcoal in gas-masks to adsorb poisonous gases fromair has been dealt with by W. Mecklenburg 16 in an important paper.The general problem of the adsorption equilibria of mixtures of twogases is of great interest. R. Lorenz and E. Wiedbrauck l7 usedcharcoal, adsorbing from mixtures of carbon dioxide and hydrogen.As the carbon dioxide in the initial gas phase is increased, the timerequired for establishing equilibrium decreases, but the amount ofgas required to saturate the charcoal increases, Carbon dioxideis adsorbed more easily than is hydrogen, temperature has butlittle effect.Other mixtures which gave very interesting resultswere carbon dioxide-carbon monoxide and carbon dioxide-ethylene.Other adsorbents investigated in relation to gas adsorption aresilica gel,l* alumina,lg titania,20 and cellulose nitrate.21 B. Foresti,22measuring the heat of adsorption of hydrogen on nickel, cannotconfirm the results obtained by Beebe and Taylor ( J . Amer. Chem.SOC., 1924, 46, 43).Adsorption from Solution.-It has been shown by H.L. Richard-son and P. W. Robertson 23 that adsorption from solution may bedetermined by a cryoscopic method. The adsorption of any sub-stance soluble in the chosen solvent may be determined from itsfreezing-point depression curves, it being a simple matter to followthe rate of change of adsorption with concentration. Adsorptionfrom various systems by means of carbon and silica gel lead E. Berland E. Wachendorff 24 to the conclusion that an important factorin adsorption is the lyophobe and lyophile character of the adsorbent,and that the behaviour of the latter with the solvent requires con-sideration. With a given adsorbent and different liquids, thecapacity for adsorbing solutes is the more pronounced thesmaller the heat of wetting of the adsorbent.W. A.Patrick and D. C. Jonesz5 believe “that adsorption bysilica gel is due to a phase separation in the capillaries caused bypreferential wetting followed by the production of highly concavesurfaces of solute which brings about a lowering of the solubilityof the solute in the solvent.” A study of the adsorption of water1% 2. Elektrochem., 1925, 31, 488.l7 2. anorg. Chem., 1925, 143, 268; A., ii, 382.18 H. A. Fells and J. B. Firth, J . Physical Chem., 1925, 29, 241.l* J. H. Berry, ibid., p. 1462; L. A. Munroe and F. M. 0. Johnson, J . Ind.-Eng. Chem., 1925, 88.F. Bischoff and H. Adkins, J . Amer. Chem. SOC., 1925, 47, 807.21 D. Costa, Cfazzzetta, 1925, 55, 540; A., ii, 956.z2 Ibid., p. 185.23 J . , 1925, 127, 553.24 Kolloid-Z., 1925, 36 (Zsiymondy Festschr.), 36 ; A., ii, 507.25 J . Physical Gi&em., 1925, 29, 1 ; A . , ii, 193COLLOID CHEMISTRY. 331from n-butyl alcohol by silica gel leads Patrick and IN. F. Ebermaii 26to the conclusion that a liquid in a capillary has a greater surfacetension than the bulk liquid under the same conditions, the differencebeing greater the higher the tempera ure. As the dispersity ofsilica gel is increased, the adsorption forces increase but in a greaterproportion. The adsorption is only due in part to increase inspecific surface, the main effect depending on the increased proximityof the solid surfaces, the radii of the capillaries so produced beingless than the range of the attractive forces causing adsorption.The upper limit for the thickness of the adsorbed layer on silica gelis about 5 molecules, the data being calculated from the adsorptionof nitrobenzene in kerosene solution.W. A. Patrick and E. H. Barclay 27 divide adsorption phenomenainto 3 classes : (u) chemical adsorption, (b) molecular adsorption,(c) capillary adsorption. “ Chemical adsorption would include allcases where attractive forces between the adsorbent and adsorbedsubstance were so strong as to be equal to real chemical attractiveforces.”An extensive paper by J. N. Mukherjee 28 concerns the nature ofhydrolytic adsorption, i.e. , cases where acids or alkalis are liberatedby the interaction between solutions of salts having a neutralreaction and insoluble substances which do not give an acid oralkaline extract with water. Hydrolytic adsorption is explainedon the author’s theory of the distribution of ions in the Helmholtzelectric double layer (Phil. Mug., 1922, 44, 330, 340).An interesting investigation by J. S. Beekley and H. S. Taylor 29deals with the adsorption of silver salts by silver iodide, this havinga definite known crystal-lattice even in the spongy precipitate inwhich form it was used. Univalent silver salts were chosen so asto eliminate the factors of varying electric charge and valence.The adsorption of silver salts followed the order: benzoate>acetate > nitrite > bromate > naphthalenesulphonate > benzene-sulphonate > nitrate > chlorate > ethylsulphate > perchlorate. I ngeneral, the less soluble salts are the more strongly adsorbed. Theresults agree with certain theoretical deductions concerning thefactors influencing the attraction of silver ions from solution bythe crystal surface. Thus, great affinity of the anion in solutionfor the silver ion (as manifested by high solubility) means lessenedattraction by the crystal and therefore less adsorption.The use of charcoal as adsorbent is indicated in several papers,and a review of the chief properties of the more important technical2 6 J . Physicol Cliem., 1925, 29, p. 220; A., ii, 284.2’ Ibid., p. 1400. 28 J. Indian C‘hena. Soc., 1925, 2, 191.29 J . Physical Chewb., 1925, 29, 942; A., ii, 855.L* 332 ANNUAL REPORTS ON THE PROURESS OF CHEMISTRY.active charcoals has been given by H. Herbst.30 Impregnation ofactive charcoal with a dry, indifferent salt decreases the purelystatic adsorption capacity in direct proportion to the salt content,but the adsorption velocity falls off more quickly. At 80% salt,the adsorption velocity in relation to that of the initial activecharcoal is nil. To determine the efficiency of a charcoal asadsorbent, E. Dingemanse and E. Laqueur 31 find the methylene-blueadsorbent test very satisfactory.The question of the adsorption efficiency of charcoal in viscousmedia is of interest. The work of G. Weissenberger and H. Wald-mann32 on the adsorption by various charcoals of iodine fromaqueous glycerol solutions and several organic solutions shows thatFreundlich’s concentration function holds in all cases. The adsorp-tion, x/m, increases as the viscosity decreases, but not in directproportion, the relation being x/m = ,/vUr where 7 = viscosityand p and Ur = constants.dealing with the adsorption of hydrogen andhydroxyl ions by activated sugar charcoal, finds that acids areadsorbed whereas alkalis such as potassium hydroxide are negativelyadsorbed. His results lead him to the conclusion that the Harkins-Langmuir orientation theory is applicable to the interface charcoal-solution. In another paper the idea is advanced that “ the adsorbedmolecules of solute are oriented at the solid-liquid interface, themore polar portion being on the solution side.” For aqueous soh-tions, the introduction of polar groups into a solute decreases itsadsorption by charcoaL3*E. J.WILLIAM CLAYTON.30 KolI. Chem. Beihefte, 1925, Zf, 1; A., ii, 966.31 Biochem. Z., 1926, 160, 407; A., i, 1500.32 Moncctsh., 1925, 45, 393.38 J . Amer. Chern. SOC., 1925, 47, 1270; A., ii, 656.34 F. E. Bartell and E. J. Miller, J . Phy8icd Chem., 1925, 29, 982

ISSN:0365-6217    

DOI:10.1039/AR9252200281

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

PHOTOCHEMISTRY, 19 14-1925Synopsis.I. Introductory. (xiii) Analogies between(i) Preliminary. Photochemical and(ii) New Inorganic Photo- Other Types ofchemical Reactions. Chemical Change.(iii) Photochemistry of Chlor-ine. (i) Thermodynamics and11. General. (ii) Radiation Theory of(i) Absorption Spectrum Chemical Kinetics andand Photosensitivity Photochemistry.Spectrum. (iii) The Photochemical(ii) Intensity and Velocity. Equivalent Law.(iii) Concentration and IV. Mechanism of PhotochemicalVelocity. Change.(iv) Absorbed Light and (i) Preliminary.Velocity. (ii) The Primary Process.(v) Temperature and ( a ) Dissociation.Velocity. ( b ) Activation.(vi) Photosensitisers and ( c ) Life of ActivatedPhotocatalysts. Molecules.(vii) Negative Photocatalysts (iii) Fate of Activated Mole-and Inhibitors.cules.(viii) Solvent and Velocity. (a) Deactivation by(ix) Photochemical Station- Radiat ion.ary States. ( b ) Deactivation by(x) Photochemical Extinc- Collision.tion. ( c ) Collisions with(xi) Photochemical Induc- Acceptors.tion. ( d ) Reaction Chains.(xii) After-effects in Photo- ( e ) Effect of Waterchemical Reactions. Vapour .111. Energetics.Photochemistry.I. Introductory.(i) Preliminary.IN choosing the last twelve years as the period to be covered by thisReport, the Reporter has been guided by two considerations.First, the commencement of the period roughly coincides with aconsiderably increased interest in the subject, due to the intro-duction by Einstein of the quantum theory into photochemistryunder the form of the Photochemical Equivalent Law.The out334 ANNUAL REPORTS ON THE PROGRESS OE’ CHEMISTRY.break of the War certainly effectively disguised this increasedinterest as far as the output of actual published work was concerned.But 1914 rather than 1919 nevertheless seems the more logicalstarting year to choose. Secondly, an excellent progress report,covering the transition years 1909-1913, was published in 1914 byWinther.2 This afforded a starting-point of another kind, and thepresent Report may, in that sense, be regarded as a continuation ofthat of Winther.Limifations of space primarily, but also other reasons, havedecided the Reporter to omit consideration, except incidentally, ofcertain important aspects of the subject.These are-the photo-chemistry of the photographic emulsion and of solid systemsgenerally ; photosynthesis in its usual special significance ; thera-peutic and other practical applications of light action which fallwithin, or border on, the field of photochemistry ; photogalvanicphenomena ; photo-reactions in organic chemistry, except wherequantitatively worked out ; phototropy ; technique of quantitativework. These subjects would either demand for adequate treatmentmore space than is available, or have been fully discussed recently,or are in too early a stage of development to justify discussion.It is believed that these omissions will give the Report a morehomogeneous character than would have been possible otherwise.(ii) New Inorganic Photochemical Reactions.Comparatively few, new, purely inorganic reactions have beendiscovered.Cario and Franck have shown that molecularhydrogen a t low pressures can be dissociated to atoms if insolatedin presence of mercury vapour by light of wave-length 254 pp. Ifmixtures of hydrogen and certain reducible gases at ordinary pres-sures are similarly insolated in presence of mercury by a lamp richin the same radiation, rapid interaction takes place.4 Amongstother gases, nitrous oxide is reduced to water and nitrogen. Mooreand W. A. Noyes, j ~ n . , ~ have shown that oxygen reacts with mercuryt o form traces of mercuric oxide in the light of the quartz-mercurylamp, even if the light is cut off just before the admission of oxygen,whilst the reaction between mercury and nitrogen peroxide isaccelerated.According to Noyes,S quartz-mercury light, fromwhich rays of shorter wave-length than 215 pp have been filteredout, will cause nitrogen and hydrogen in presence of boiling mercuryt o form ammonia up to about the thermodynamic equilibriumconcentration. Warburg has studied the ozonisation of liquid~ x y g e n . ~ Winther has shown that oxygen can be ozonised inpresence of zinc oxide by irradiation with light of wave-lengthPHOTOCHEMISTRY, 19 14-1 925. 335which would have no action on oxygen alone. The zinc oxide isunchanged. The mutual reaction bet ween ozone and hydrogenperoxide solutions is much accelerated in light.g The photo-decomposition of gaseous chlorine dioxide was shown by Bowen loto give an unstable, reddish-brown liquid.The subject was fol-lowed up by Booth and Bowen 11 and by Bodenstein, Harteck, andPadelt.12 Itcan also be formed by irradiation of a mixture of ozone and chlorinewith red light, which is absorbed by, and activates, the ozone.A number of new organic substitution and addition photo-reactions in which the halogens take part have been discovered, butwill not be enumerated here. It may, however, be mentioned thatthe combination of carbon monoxide and oxygen and the decom-position of sulphuryl chloride l4 and of chlorine monoxide l6 mustbe added to the list of reactions which are sensitised for visiblelight by chlorine. Bonhoeffer l6 has shown that the decompositionof carbonyl bromide and of ozone will take place in blue light in thepresence of bromine.Winther 1 7 has shown the oxidation ofhydriodic acid solutions by oxygen to iodine to be sensitised forblue light by I,- ions first formed by a dark reaction, and has pointedto other previously known reactions as being examples of suchauto-sensitisation. von Strachoff l8 draws the same general conclu-sion. Trautz l9 has demonstrated the photochemical union ofcarbon monoxide and bromine. Noddack 2o and Griiss 21 havestudied the chlorination of trichlorobromomethane dissolved incarbon or silicon tetrachloride, and Griiss21 has shown that, inpresence of bromine and in carbon tetrachloride solution, blue lightcan cause the oxidation of trichlorobromomethane by oxygen tocarbonyl chloride.von Goldberger 22 has demonstrated thatcarbonyl chloride is reduced by hydrogen in ultra-violet light, carbonmonoxide and hydrogen chloride being the chief products.Dhar 23 has shown that a number of reactions that proceed withappreciable velocities in the dark are materially accelerated bylight. Such are the reduction of iodine, bromine, a,nd other oxidisingagents by various organic acids and their salts; the reduction ofiodine by nitrites and by ferrous salts, etc. The equilibrium2Fe++ + I,- 2Fe*++ + 31- is moved to the right when the solutionis insolated 24 by yellow light.25 The slow decomposition of aqueoussolutions of alkali metal perchlorates, periodates, and iodates bylight from a powerful quartz-mercury lamp is noted by Oertel26(that of bromates and chlorates had already been recorded 27).Matthews and Curtis 28 have shown that mixtures of potassiumiodide with either the chlorate, bromate, or iodate undergo com-paratively rapid decomposition in these circumstances, with liber-The latter workers showed the liquid to be C1,0,336 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.ation of iodine.According to Mukerji and D h ; ~ r , ~ ~ sunlight acceler-ates the decomposition of nitrous acid solutions. The photode-composition of nitrogen pentoxide is sensitised for blue light by thepresence of the peroxide.30 Norrish and Rideal31 have shown thatlight of wave-length about 275 pp causes the union of hydrogen andsulphur vapour at 300-340°, and Benrath32 records the photo-reduction of aqueous solutions of sulphur dioxide, and of the oxy-acids of selenium and tellurium, to the free element by oxalic acid.Sulphuryl chloride can be decomposed by light of a suitable wave-length.l4> l9 The reaction is a complex one.According t o Baur,33pure solutions of potassium ferrocyanide are not acted on by light,the photosensitivity of ordinary solutions being due to the presenceof f erricyanide .The great majority of photo-reactions in which the electro-positive constituent of a metallic compound is the active photo-chemical agent are photo-oxidations of organic substances (chieflyaliphatic alcohols, hydroxy-acids and dicarboxylic acids), theinorganic compound either being reduced to a lower stage of oxid-ation or acting as a carrier for oxygen.Many have been noted forthe &st time during the period under review, and, in particular,the photochemical properties of some of the rarer metallic com-pounds have been investigated. The results, however, are of theusual type, and need no further notice. One curious reactiondeserves mention-that between zinc oxide and an aqueous silvernitrate solution in sunlight. Following up the work of others,Baur and Perret 34 showed that, whilst the final result of the reactionis essentially the production of metallic silver, oxygen, and zincnitrate, an unstable peroxide of silver (probably AgzO,) is formed asan intermediate product of the reaction.(iii) Photochemistry of Chlorine.The last twelve years have been marked by intensive work,much of it quantitative, directed towards the elucidation of themechanism of already known reactions. Chlorine still remainsthe photochemical element of mystery, and the majority of paperspublished on the photo-reactions of this element still note somestriking new experimental results or conclusions-not always, itis true, subsequently confirmed.The following is a summary ofpapers on the photochemistry of chlorine which have appeared sincethe beginning of 1914 :From the laboratory of Jesus College,Oxford, have come experimental papers by D. L. Chapman andWhist0n,3~ and by M. C. C. the first two dealing chieflywith the effect of concentration and the third with that of lightCombination with hydrogenPHOTOCHEMISTRY, 1914-1925.337intensity. The latter subject has also been studied by Baly andBarker.37 Weigert and Kellermann 38 have investigated the initialstages of the reaction by new experimental methods. Coehn and hiscollaborators 39 have studied the effect oh the reaction of the additionof traces of water vapour to the thoroughly dried gases. Marshall,after showing that the introduction of hydrogen atoms into ahydrogen-chlorine mixture in the dark caused formation of hydrogenchl~ride,~O investigated the photochemical reaction from the pointof view of quantum efficiency over a large range of pressure.41Experiments of this nature promise to be of great value. Quantumefficiency measurements have also been made by Kornfeld andMiiller.42 Padoa and Butironi 43 have studied the temperaturecoefficient in light of various wave-lengths, whilst Coehn and Jung 39dand W.Taylor 44 have published work on the effect of wave-lengthon velocity. Padoa and Butironi found the reaction to go withlight of wave-length 530-550 pp, Coehn and Jung conclude that540 pp is the limiting wave-length which will bring about the change,whilst Taylor gives 490 pp, the limit of the continuous absorptionband of chlorine, as the same critical wave-length. Bowen45 hascriticised these conclusions of Taylor and of Coehn and Jung.Finally, inhibition phenomena due to the presence of ammoniahave been investigated by Norrish.46 Theoretical papers on themechanism of the reaction have been published by B~denstein,~'Gohring,4s D.L. Chapman and M. C. C. Chapman,49 Bertho~d,~Oand Cathala.51Combination with carbon monoxide. This reaction has beenworked on by Bodenstein,l3 Bonhoeffer,16 Cathala,52 and Coehnand Tramm.39a, These last authors, and also Bodenstein, foundthe reaction to be much retarded if the gases were exhaustivelydried.Cornbination with sulphur dioxide. This reaction has been studiedby Trautz,lgLe B1anc,l4Bonhoeffer,l6 and by Coehn and Tramm.39aJCombination with ozone.Substitution reactions. The chlorination of methane has beenworked on by Whiston, 53 of solutions of trichlorobromomethane byNoddack 2o and by Gruss,21 of toluene at - 80" by Book and Eggert,54and of solutions of various aliphatic compounds in carbon tetra-chloride by Benrath andReactions sensitised by gaseous chlorine.Work has been done onthe decomposition of sulphuryl chloride,14 ozone,16 and chlorinemonoxide,15 the union of carbon monoxide and oxygen,13 and thesynthesis of ~ a t e r . ~ 6Remtions i n aqueous solution. The photo-decomposition ofchlorine water has been studied under various conditions by Mil-In red light, Cl,06 can result.1338 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.b a ~ e r , ~ ~ Benrath and T ~ c h e l , ~ ~ Benrath, Schaffganz, and Ober-b a ~ h , ~ ~ and by Allmand, Cunliffe, and Maddison.60 Anderson andH. S. Taylor 61 report that a solution of hydrogen peroxide con-taining a small amount of chlorine decomposes very rapidly inultra-violet light.Nasaroff 62 has worked on the kineticsof the addition of chlorine to cinnamic acid in carbon tetrachloridesolution.According to Plotnikov, 63 solutions of chlorine in carbontetrachloride, exposed to light, undergo a periodic variation in titre.Griiss and Benrath and Hertel55 state, on the other hand, thatperfectly pure carbon tetrachloride is not an acceptor for chlorine.Plotnikov 64 nevertheless does not hesitate to assert the real existenceof periodic reactions as a new type of photochemical change.In view of theremarkable photochemical properties of the element, attemptscontinue to be made to " activate " it in the absence of an acceptor.Le Blanc and Volmer 65 and Bodenstein and H. S. Taylor 66 havebrought hydrogen into contact with chlorine within an interval of1/1000-1/1500 second after the light had been cut off from thelatter, but without any hydrogen chloride formation.Similarfruitless experiments were made by Wendt, Landauer, and E ~ i n g . ~ ~On the other hand, these last observers were able to confirm olderwork in that a pre-insolation of chlorine alone shortens the inductionperiod for a subsequent photo-reaction between hydrogen andchlorine. '' Activation " of chlorine for subsequent dark reactionsis reported by Venkataramaiah 68 and by Schaum and Feller.69Venkafaramaiah used both electrical discharges and radiation fromiron arcs, and claims to have evidence that some sort of a complexmolecule is formed. 70 The latter authors used electric dischargesonly. They, as also Wendt and his co-w0rkers,~7 suggest theformation of C1, as a possibility.Gohring48 draws the same con-clusion from another point of view. Radel 71 and Jones 72 havestudied the formation of the clouds produced in moist chlorine orchlorine-air mixtures on insolation, and their results in both casesare of considerable interest. The same phenomenon has beenremarked by Weigert and Kellermann.38bFinally may be mentioned a paper by Weigert 73 in which anattempt is made to work out a general mechanism for all gaseouschlorine phot.0-reac tions.Miscelkaneous reactions.,4ction of Eight on, and actication of, chlorine.11. General.(i) Absoyption Spectrum and Photosensitivity Spectrum.It is, of course, universally recognised that absorption of radiatlion,not necessarily by the reacting substance, must precede photoPHOTOCHEMISTRY, 19M-1925.339chemical change. On the other hand, answers to the followingqueries still remain t o be given. Amongst those rays which areabsorbed, why are some photochemically active and others not ?If a particular wave-length inside an absorption band can causechemical change, will this also be the case for every other frequencyinside the band? Assuming that a certain frequency range canbring about photochemical change, how will the photosensitivity, orrate of chemical change for the same incident energy (expressed inergs/cm.2. second), depend on the frequency ? Given the quantita-tive absorption spectrum, the answer to this last question is, ofcourse, directly connected with the rate of chemical change per unitof absorbed energy and its dependence on frequency, a subject whichhas been inuch worked on in recent years.For the moment, how-ever, we will consider the matter from the point’ of view set outabove.To account for the marked differences observed between thephotochemical effects resulting from absorption in different parts ofthe spectrum, several workers have postulated the existence of twotypes of absorption band-photochemical and thermal. Such adistinction was already made by P l o t n i k ~ v , ~ ~ prior to 1914, and,in a different form, is implicit in Henri and Wurmser’s Law ofElementary Photochemical A b s ~ r p t i o n . ~ ~ Winther and Oxholt-Howe, 76 from their work on photodecomposition of organic ferricsalts, conclude that a photosensitive substance consists of two“ constituents,” one photosensitive and one absorbing purelythermally.The observed absorption curve results from the super-position of the absorption curves for the two “ constituent’s.”Tian9 regards observed absorption curves as complex in the sameway. Andrich and Le B l a n ~ , ~ 7 working on the bromination oftoluene and of its solutions in different solvents, found that short-wave ultra-violet light caused rapid reaction in cases where theabsorption spectrum in that region resembled that of free bromine(photochemical absorption) and little or no action in cases where theabsorption curve indicated marked solvation of the bromine (thermalabsorption). Coehn and S t u ~ k a r d t , ~ ~ from work on the decompos-ition and synthesis of the hydrogen halides, drew conclusionspractically identical with those suggested years before by Luther 79-namely, that photochemical action is connected with the occurrenceof steep, well-defined bands, indicating resonance and forced vibra-tions in the absorbing molecules, whilst broad and ill-defined bandsdenote thermal absorption.Luther was thinking in terms of theelectromagnetic theory of light absorption, but his ideas on themechanism of degradation of energy during the process of thermalabsorption are applicable, with slight changes, when using the theor340 ANNUATJ REPORTS ON THE PROGRESS OF CHEMISTRY.of discontinuous absorption. Thus, Warburg, whilst admittingthat a change in the character of absorption with frequency (andthus a difference in character between thermal and photochemicalabsorption) is possible,80 if unlikely, suggests 81 that the loss ofenergy during absorption, by collision of the absorbing moleculeswith neighbouring molecules, which is regarded as the cause of broadabsorption bands and lines, may also be responsible for suchabsorption resulting in little or no chemical change, but in theproduction of heat.In the case of the continuous absorptionbands of chlorine and bromine, Ribaud 82 explains the same energydegradation as due, not to collisions with contiguous gaseousmolecules, but to intra-moZecuZar perturbation, probably electronicin nature. (Energy degradation of this sort had also been takeninto account by Luther.) It may be significant that chlorine andbromine are both photochemically active within these regions.In the case of chlorine, indeed, W.Taylor 44 draws the conclusionthat only absorption within the continuous absorption band willphotoactivate the gas, and that absorption in the neighbouringregion of fine structure bands is without effect. Bowen45 haspointed out an apparent flaw in his reasoning. I n any case, it iscertain that the first question posed above can only be answeredwhen we have more exact knowledge of the mechanism of absorptionof radiation by molecules. Such knowledge is accumulating fairlyquickly [see Section IV (ii)], and in these circumstances, the attemptsof Weigert 83 to work out from this point of view the mechanism oflight absorption and photochemical change are perhaps somewhatpremature.The question of the threshold or critical frequency necessary forphotochemical change has been attacked in several ways, but isstill undecided.In the case of the decomposition of sulphur dioxideto sulphur trioxide and sulphur, Hill 84 concludes that, within thesulphur dioxide absorption band, any frequency will decompose thegas, provided that the intensity is sufficient. Plotnikov’s 74 ideathat only a small range of frequency near the long wave-lengthlimit of the band is active, is shown not to hold by Andrich andLe Blanc 77 in the case of the bromination of toluene, and is indeedrefuted by many other examples. A number of attempts have beenmade to calculate the lowest critical frequency which will causereaction from considerations based on the quantum theory.Theirvalidity is, however, very doubtful. For example, the heat ofdissociation of a single molecule has been equated to the magnitudeof a quantum (which gives the limiting frequency) by Bowen 85 inthe case of the formation and decomposition of the hydrogen halides,by Bowen and Sharp in the case of the dissociation of nitrosyPHOTOCHEMISTRY, 1914-1925. 341chloride, and by Coehn and Jung 39d for the formation of hydrogenchloride. Volmar 87 has made similar thermochemical calculationsof the limiting frequency required for the photolyses of certainaliphatic derivatives, and Job and Emschwiller s8 have used thecritical frequency in the decomposition of ethyl iodide to makecalculations of the same type.now declares that there are no grounds for expecting such relationsto exist. This is the view of Fran~k.~O Rideal and Williams25find that the minimum frequency required to effect the photo-oxidation of Pe*+ ions by iodine ( 5 7 9 ~ ) corresponds to the resonancepotential of iodine molecules (2.34 -J= 0.2 volts).Finally, attemptsto calculate the limiting frequency by equating the correspondingquantum, in accordance with the well-known radiation theory ofW. C. McC. Lewis and of Perrin, with the molecular heat of activ-ation, as calculated from the temperature coefficient of the thermalreaction, have not been uniformly successful. Daniels and John-ston30 did not find nitrogen pentoxide photosensitive at 1.16 p, asthe theory predicted, whilst what at first appeared to be an excellentconfirmation in the case of the photo-depolymerisation of dianthra-cene 91 has recently been shown to be fallacio~s.~~ The calculationsby €€ill 84 of the wave-length required for sulphur dioxide decom-position do not carry conviction, nor does the extent of agreementwith the theory found by W.A. Noyes, jun., and Koupermang3 inconnexion with oxalic acid decomposition. On the other hand,Griffith and Shutt 94 found ozone to be photosensitive a t about700 pp as forecasted, whilst Norrish and Rideal consider that thepredictions of the theory have been confirmed in the case of thephotochemical union of hydrogen and sulphur .31With regard to the observed dependence of photosensitivityon frequency inside a given band, practically all the data publishedindicate that it increases with frequency. Such data include thework of Boll95 on the hydrolysis of the chloroplatinic acids, ofSpencer 96 on the photolysis of sodium hypochlorite solutions, ofWinther and Oxholt-Howe 76 on the decomposition of the ferricsalts of organic acids, of Tian 97 on the decomposition of hydrogenperoxide solutions, and of W.Taylor 44 on the combination ofhydrogen and chlorine. Berthelot 98 once again states his views onthe analogy between frequency in photochemical reactions andtemperature in thermal reactions-an analogy in the light of whichthe experimental facts appear normal.Weigert 836 has pointed outthat, if the Einstein Law [see Section I11 (iii)] holds, the photo-sensitivity-wave-length curve should be similar to the absorptioncurve, but displaced unsymmetrically towards the red. Thisdisplacement has long been known to occur in certain reacti~ns,?~bBowen, in his late342 ANNUAL REPORTS ON THE PROGRESS OF CEEMISTRY.and the considerable sensitivity to the red of iodine-potassiumoxalate mixtures reported by Berthoud and Bellenot 99 may perhapsbe noted in this connexion.Mention should finally be made of new experiments comparingthe action of complex light with the sum total of the action producedby the component bands or rays. Previous to 1914, Luther andForbes loo had found these to be equal for the oxidation of quinine bychromic acid, whilst Plotnikov 74 had obtained considerably greaterreaction, in the case of the addition of bromine to cinnamic acid,from the summed effects of the single rays, than when using thecomplex beam.Padoa,lol reinvestigating this reaction, obtainsqualitative confirmation of Plotnikov’s results, whilst findingconsiderable complications owing to the existence of inductionperiods. The results depend on the order in which the differentstrips of the spectrum are allowed to act on the solution. The sametype of result was got for the decomposition of Eder’s solution, andfor the ferric chloride-oxalic acid arid the hydriodic acid-oxygenreactions.lo2 On the other hand, for the hydrogen-chlorine reaction,the yield in white light much exceeded that given by the summedreactions of the different parts of the spectrum.lO1 The significanceof these data cannot yet be discussed with advantage.Attentionmay, however, be directed to some probably relevant results ofKuhn,l03 who found the quantum efficiency for ammonia decom-position to decrease with increasing monochromatism of the ultra-violet light used.(ii) Intensity and Velocity.Themethods used for altering the light intensity differ considerably-interposition of a number of sheets of tissue paper of knownextinction, of various forms of diaphmgms of known fractionalaperture or of crossed Nicol prisms ; change in slit width when work-ing with dispersed monochromatic light ; variation of distancebetween light source and reaction vessel; a rotating sector.Theuse of the last device seems to the Reporter to be open to an obviousobjection if the object of the experiment is to discover the formof the functional relation between velocity and intensity-it is, onthe other hand, well adapted for the investigation of true inductionprocesses or of dark reactions superposed on primary light reactions.Proportionality between intensity and velocity has been found inthe cases of the hydrolysis of the chloroplatinic acids,05 the decom-position of hydrogen peroxide solutions and also of water to hydrogenperoxide and hydrogen,0 the decomposition of potassium cobalti-oxalate solutions,lO* and for the initial stages of the photolysis ofThis has been investigated in comparatively few casesPHOTOCHEMISTRY, 1914-1 925.343uranyl formate solutions.105 I n the last case, the extreme intensitiesused were in the ratio of about 1 : 280. The case of the combinationof chlorine and hydrogen is a particularly interesting one. Baly andBarker 37 found that a sixfold increase in the intensity increased thevelocity about ten-fold, and Cathala 51 expresses their results byproportionality between 13’2 and rate. On the other hand, M. C. C.Chapman 36b for an intensity ratio of 6 : 1, Marshall 41 for a ratio of20 : 1, and Kornfeld and Muller 42 for a ratio of 64 : 1, found pro-portionality between intensity and velocity. In Marshall’s experi-ments, the total pressure was only 5.9 em. of mercury-all otherinvestigators were using mixtures at about one atmosphere pressure.Berthoud 50 is of opinion that Mrs.Chapman’s earlier experiments 36asuggest that the rate of this reaction may, in circumstances, beproportional to P. D. L. Chapman lo6 thinks this may be so incomplete absence of any inhibitors.The proposed relation is of much interest, as it would suggestthe primary reaction to be the dissociation of chlorine molecules toatoms as the result of their absorption of light, the chlorine atomsthen reacting further at a rate proportional to the first power of theirconcentration. This actually appears to be the type of mechanismin the photosynthesis of hydrogen bromide from its elements , whereBodenstein and Liitkemeyer 10’ have shown that the rate of reactionis proportional to the square root of the rate of energy absorption,and thqrefore presumably to IY2.This relation between velocityand intensity has also been found by Berthoud and Bellenot 99 forthe reaction between iodine and potassium oxalate in aqueoussolution. Earlier kinetic experiments of Dhar 23d point to the sameresult, which has been confirmed recently by Chaprnan.lo6 Accord-ing to Berthoud,log a similar relation holds for the addition ofbromine to cinnamic acid, to a-phenylcinnamonitrile , and tostilbene. In the carbon dioxide assimilation reaction, sensitised bychlorophyll, the rate of assimilation increases less rapidly thanthe intensity.log For the photo-oxidation of hydriodic acid toiodine (sensitised by I,- ions), Winther, 110 working with mono-chromatic light of ?, = 366 pp, obtains the remarkable result thatthe rate (over a fifty-minute interval) at first increases more or lessproportionally with the intensity, and then, comparatively rapidly,becomes independent of any further increase in the latter.Ber-thoud lo8 believes, from Winther’s figures, that the 11’2 relationholds here also.One other case has been noted, in which the relation betweenvelocity and intensity is similar to that reported by Baly andBarker 37 for the hydrogen-chlorine reaction, ~ L ‘ i z . , the destruction ofcertain fluorescing dyes, such as eosin, in aqueous solution by light344 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.A very rapid disappearance of the fluorescence in intense light wasfirst observed by Perrin.lll Wood 112 showed that a certain influxof light a t high intensity broke down the dye far more extensivelythan the same amount a t low intensity, and this was confirmed byPringsheim,l13 who also discusses possible explanations of theeffect in this and in a subsequent paper.l14Our knowledge of the subject of threshold intensity remains muchas it was.Whereas, on the electromagnetic theory of light absorp-tion, the existence of such a definite effect appeared quite natural,this is not the case when using the quantum theory. Hill 84 indicatesthe possible presence of such an effect in the decomposition of sulphurdioxide by light of A = 313 ~ ~ f l . . And the experiments of Dhar andSanyal 115 on photosynthesis in tropical sunlight may perhaps beinterpreted in the same way.But the matter requires carefulinvestigation, with due regard paid to the time factor. Of course,in reactions like the breakdown of the dye solutions referred toabove, where the mechanism probably involves collision betweentwo molecules activated by light, a practical threshold intensity maywell occur.(iii) Concentration and Velocity.The controversy between the intensity and absorption formulationsof photochemical kinetics was cleared up just before the beginningof the period covered by this Report, and, as is known, in a waywhich demonstrated that the two conceptions represented extremecases of a more comprehensive formulation. The introduction ofthe quantum theory gave a rational theoretical basis to thisgeneralised mode of treatment, whilst the results of experimentalwork carried out during the last twelve years can, with few exceptions,be satisfactorily fitted into the scheme.With regard t o the con-centration of the absorbing substance, in the great majority of ca'sesthe true order of the reaction is one, and the apparent order liesbetween the limits of zero and one. With complete absorption ofthe active radiation, it is zero. Such was, for example, the case (ornearly so) in experiments on the decomposition of sulphurylchloride,14 of ammonia 103 and of uranyl oxalate solutions,l16 andin the hydrolysis of monochloroacetic acid by water.l17 Caseswhere the order lies between zero and unity, depending on thethickness of insolated layer, the concentration of the absorb-ing substance or the extent of the reaction are (absorbingsubstances mentioned first) the reduction of aromatic ketones 118or of ammonium dichromate 119 by aliphatic alcohols, and thedecomposition of carbon tetrachloride solutions of chlorine monoxideand chlorine dioxide,120 aqueous solutions of sodium hypochl~rite,~PHOTOCHEMISTRY, 19161925.345formic acid, 121 oxalic acid 122 and uranyl forrnate,lo5 and of nitrosylchloride 86 and formaldehyde vapour.22 Reactions found to be ofthe first order, and probably of the same 0 + 1 type, were the unionof very dry chlorine and carbon monoxide,13 of sulphur vapour andhydrogen,31 the decomposition of potassium permanganate solu -ti0ns,1~~ and the reduction of titanium tetrachloride by mandelica~id.12~ Reactions of the second order for the absorbing constituentwere found in the cases of the hydrolysis of the chloroplatinic acidsYg5the addition of bromine to a-phenyl~innamonitrile,~~~ and thede-ozonisation of ozone-oxygen mixtures.126 Further, Boden-stein 13 found that the velocity of reaction of ordinarily dried carbonmonoxide-chlorine mixtures was of the second order with respectto chlorine.The hydrogen-chlorine reaction also shows discrepantresults. Whereas n for chlorine, according to D. L. Chapman andWhiston,35 is unity (possibly of the 2 +l type), M. C. C. Chapman 36afinds n = 1.6, whilst Berthoud50 would wish to conclude from herresults that n = 1, and Cathala 51 that n = 1.5.There are also two cases in which the observed orders of reactionare difficult to reconcile with the results given by quantum efficiencyexperiments, v i x ., the decomposition of solutions of hydrogenperoxide 93 97$ 1.27 and of potassium cobaltioxalate.10* Details cannotbe gone into, but one would expect in the two cases higher andlower orders, respectively, than those actually found.Finally, those cases 999 107 in which the velocity varies as 1u2 alsogive, or tend towards, n = 0-5 for the reaction order of the absorbingsubstance.Xensitisecl reactions invariably have an order of the 0+1 type forthe optical sensitiser. This is the case for the following chlorine-sensitised reactions : ozone l6 and chlorine monoxide 15 decom-position, water synthesis ; 46 for the bromine-sensitised transform-ation of maleic into fumaric ester; 128 for the decomposition ofoxalic acid in aqueous solutions sensitised by a low UO,SO,con~entration.~5~ 122The reaction order for non-absorbing substances is, with very fewexceptions, of the 0 + 1 type.Examples are numerous, and onlythose will be referred to in which a change in order was observedaccompanying a change in concentration. For example, n fortrichlorobromomethane in its reaction with chlorine increasescontinuously from zero as the mixture is diluted with carbontetrachloride 2o or silicon tetrachloride.21 Lazareff 129 investigatedthe photo-oxidation of solid dyes by oxygen at various pressures upto 120 atmospheres, and found that, as the pressure increased, n,originally unity, steadily fell. In the reactions between titaniumtetrachloride and mnndelic acid 124 and between uranyl sulphate an346 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.oxalic acid 122 in aqueous solution, the same dependence of n on theconcentration of the organic acid was experimentally found-a zerovalue at high concentrations, becoming greater as the concentrationwas decreased.The best known exception to this rule is perhapsafforded by hydrogen in the hydrogen-chlorine reaction, where ncan approach - 0.5 in certain circ~mstances.3~b We are here,however, dealing with a definite inhibiting action of the hydrogen,bound up with the simultaneous presence of oxygen.(iv) Absorbed Light and Velocity.The form of the function connecting these two magnitudes isintimately bound up with what has been discussed in the twopreceding sections, i.e., it depends on the relation of intensity tovelocity, and on the reaction orders for the absorbing and non-absorbing reactants.The simplest case occurs when velocity isproportional to the first power of the intensity, and all the relevantvalues of n are zero. Velocity will then be proportional to theabsorbed light, independent of any of the concentration terms inthe system (incidental complications apart), and moreover will havethe maximum value possible with the given experimental conditions(light source, disposition of reaction vessel, temperature, etc.).In any case, if the order for the absorbing substance is of the 0 + 1type and the concentration of any non-absorbing substance suffi-ciently high, the velocity at any instant will be proportional to therate of absorption of light.It does not seem necessary to give a list of reactions in which suchproportionality has been found.In any case, it clearly exists inall those reactions where the Einstein Photochemical EquivalentLaw holds. Where the true order of n for the absorbing substanceis other than unity, this proportionality will disappear. Thus, inthose cases 99 107 where n is 0.5, the velocity is proportional to thesquare root of the rate of absorption of energy. Whilst in caseswhere n = 2 (e.g., the hydrolysis of the chloroplatinic acids 95 andpossibly the decomposition of hydrogen peroxide solutions l2 7,an increase in the rate of absorption of energy caused by increasingthe concentration of the absorbing substance will bring about aproportionately greater increase in velocity.(v) Temperature and Velocity.!Phis relation has been determined for a large number of reactions,too many to enumerate.The values obtained still justify the truthof the statement that the temperature coefficients of photochemicalreactions are, as a rule, less than those of thermal reactions. Thus,omitting reactions in solids, values of 1.05 or less are reported bPHOTOCHEMISTRY, 19 14-1 925. 347Berthelot 130a for the photolysis of aqueous solutions of laevuloseand of oxalic acid-ferric chloride mixtures, by Bolin and Linder 131for the decomposition of Pehling’s solution in glass, by Plotnikov forthe oxidation of aqueous ethyl alcohol by ammonium dichromate 119and for the polymerisation of vinyl chloride,13z by Padoa andMinganti 133 for the decomposition of Eder’s solution in ultra-violet light, by Bodenstein 13 for the union of chlorine and carbonmonoxide and for the chlorine-sensitised reaction between oxygen andcarbon monoxide, by Kuhn lo3* 13* for ammonia decomposition, byRideal and Norrish 123 for the decomposition of permanganatesolutions, and by Anderson and Robinson122 for the uranyl sulphate-oxalic acid reaction.On the other hand, temperature coefficientsas high as 3 are noted (before 1914, the only reactions known withvalues greater than 1.5 were certain oxidations in red light investi-gated by Trautz,135 and the bromination of toluene 136), particularlyin a number of reactions between oxalic and formic acids (or theirsalts) and oxidising agents, worked on by Dhar 23d and by Berthoudand Bellenot .99 These reactions have comparatively high darkreaction velocities, a fact which may well be significant.Temper-ature coefficients less than 1 are reported by Trautz l9 for the unionof chlorine and sulphur dioxide, by Bodenstein 137 for the unionof chlorine and carbon monoxide (confirming a former observationof Chapman and Gee13*) and by Pad0a1~~ in the case of the hydrogen-chlorine reaction, when carried out in presence of a trace of iodine,above 20°, and in blue or violet light.Plotnikov 64 still holds to his view that the temperature coefficientsof all photochemical reactions can be divided into three groups,centring around values of 1.03, 1.20, and 1.40.But the evidence isstrongly against him. In only one case (Kuhn’s work on ammoniadecomposition 134) has the temperature coefficient been referred tothe same amount of light absorbed at the different temperatures.This point is important if there is any appreciable change in extinc-tion coefficient with temperature.One relation of importance emerges from the mass of data. Thetemperature coefficient of a given reaction sensitive to a wholeseries of frequencies would appear to increase with increasing wave-length. For example, Padoa and Minganti,133 for the decompositionof Eder’s solution, found a value of 1.05 for ultra-violet light,increasing to 1-75 for green light, whilst Padoa and Butir0ni,4~ forthe hydrogen-chlorine reaction, found 1-17 for ultra-violet light,increasing to 1.50 for green light.Similarly, for hydrogen peroxidedecomposition, Tian found 1.15 when using a light source rich inshort ultra-violet radiation, whilst Mathews and Curtis 140a obtained1.5 (imagined by them to be rather too high) employing a Uvio348 ANNUAL REPORT8 ON THE PROGRESS OF CHEMISTRY.lstmp, and K ~ r n f e l d , l ~ ~ also using low-frequency ultra-violet light,got 1-32. Griffith and McKeown 141 quote similar figures for ozonedecomposition. In view of the fact that thermal temperaturecoefficients become less a t higher temperatures, the analogy drawnby Boll 95 and by Berthelot 1309 98 between temperature in thermalreactions and frequency in photochemical reactions gains interestfrom the above data.One exception to the generalisation has beenreported, also by P a d ~ a , l ~ ~ who finds that, for the reaction betweenhydriodic acid and oxygen in aqueous solution, the temperaturecoefficient decreases with increasing wave-length. An importantpaper by Tolman 143b on the theory of the subject will be mentionedlater.(vi) Photosensitisers and Photocatalysts.By pholosensitisers are understood those substances which, whenadded to a chemical system, by virtue of the light they themselvesabsorb without undergoing permanent change, make the systemsensitive to light in a frequency region where it was previouslynon-sensitive, or, less strikingly, materially increase its photo-sensitivity in a certain part of the spectrum.The most interestingnewly discovered examples of photosensitisation, in which thehalogens,l3. 14. 159 16, 17, 18, 2 1 mercury,% 49 6 and zinc oxide 8,34are the photosensitisers, have already been menti0ned.1~4 Suchphotochemical reactions are clearly simpler in one respect thanreactions in which the absorbing substance disappears during theinsolation, and, as such, are being made the subject of much study.Some of the conclusions already drawn will be mentioned later.Reference may here be made to two suggestive papers on opticalsensitisation by Winther,8? 145 to Baur’s views on the same sub-ject,146 and to the work of Fajans 147 on the sensitisation of solidsilver bromide by ionic adsorption.Photocatalysts are, strictly speaking, those substances, which,when added to an insolated system in which a photochemicalreaction is already taking place, increase the speed of this reactionwithout in any way affecting the amount of light of the effectivewave-length absorbed, or undergoing any permanent change.From this point of view, many so-called photocatalysts are reallyphotosensitisers, as, for example, is the case in certain of the organicdecompositions and oxidations brought about in visible light inpresence of small quantities of ferric or uranyl salts.Our know-ledge of the mode of action of photocatalysts themselves is scanty,although some very interesting work has been done during theyears under discussion. Much of this relates to the catalytic effectof traces of water vapour, which is just as striking in photochemicaPHOTOCHEMISTRY, 19 144925.349as in thermal reactions. Intensive drying will more or less com-pletely inhibit the combination of chlorine with carbon mon-oxide 1 3 ~ 3 9 ~ 9 b and with sulphur dioxide,l4~ 39a~ b and the dissociationof hydrogen chl0ride.3~a~ b It similarly inhibits the union ofhydrogen and chlorine in visible light,39a9 b y c but not completelyunless the water vapour pressure is reduced to a calculated figureof lo-' mm.39d I n ultra-violet light, even drying to this limit stillpermits of complete combinati0n.3~c According to Coehn andTramm, drying has no effect on the photochemical union of hydrogenand oxygen,148 or on the decomposition of hydrogen bromide ori0dide.3~01b Baker and Carlton dispute the first of these results,finding water to be a positive catalyst.The case of the reaction2CO + 0,Z 2C0, is a curious one. Coehn and Sieper 149 confirmthe former observations of D. L. Chapman, Chadwick, and Rams-bottom 150 to the effect that water vapour is a negative catalyst forthe dissociation, whilst Coehn and Tramm 151 find it to have noinfluence on the combination. Some of the explanations given ofthe above results will be considered in Section IV (iii) e.The work of Griffith and his collaborators on the effect of variousgaseous additions on the deozonisation of ozone by visible and long-wave ultra-violet light is of interest.In the presence of hydrogen,this decomposition is catalysed (quite apart from the simultaneouschemical interaction with the hydrogen), and the results are inter-preted in terms of fruitful collisions between newly-formed, high-energy water molecules and ozone mo1ecules.l26 In a secondpaper,152 the effect of other gases is investigated and compared,and found to increase in the order CO,, CO, Ne, A, He, H,. Thesame type of collision theory fits the results best.(vii) Negative Photocatalysts and Inhibitors.The study of this subject has resulted in the discovery of newfacts, but of little else. Oxygen, in addition to the many knownreactions, has been found to retard the decomposition of solutionsof organic ferric and also one of the photo-changes under-gone in light by tetrabenzoylethylene.153 On the other hand, Bolland Henri 154 showed that it had no effect on the photolyses ofsolutions of the chloroplatinic acids or of dilute UO,SO,-H,C,O,mixtures, facts which were used by them to refute the general r6Zeassigned by Bodenstein 155 to oxygen in photochemical reactions.M.C. C. Chapman 36a has shown that, in the case of the hydrogen-chlorine reaction, the retarding effect of oxygen is probably boundup with the fact of the presence of hydrogen. The same view, in itspecial sense, is taken by Norrish,46 whilst Gohring 48 and Cathala 51believe chlorine dioxide formation to be the explanation. Theorie350 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of general application are put forward by Weigert 83b and byWinther, lg5 based respectively on the oxygen molecules beingacceptors for electrons or for active secondary radiation.Waterretards carbon dioxide disso~iation,~4~ the chlorine-sensitisedcombination of carbon monoxide and 0xygen,l3 and (when presentin larger amounts than for the gas reactions) the reduction ofaromatic ketones by alcohols,ll8 the polymerisation of vinyl~ h l o r i d e , l ~ ~ and the transformation of N-chloroacetanilide intop-chloroacetanilide. 156Nitric oxide and sulphur dioxide are negative catalysts for thechlorination of methane 53 and the dissociation of carbon dioxide 39brespectively, whilst examples of reaction products themselvesacting as inhibitors are furnished by hydrogen bromide in thehydrogen-bromine reaction lo' and by hydrogen in ammoniadecomposition.103 (More cases have also been observed in whichthe product of reaction retards by the mere fact of its absorbing theactive radiation-internal light filter action or negative photosensitisa-tion.) I n several cases of photo-oxidations of organic acids bymetallic salts, chlorine ions have been found to exert a markedretarding effect.105~ 1249 157, 158 Retarding agents for the decom-position of chlorine water have been worked on by Milbauer 57 andby Benrath and his pupils,58* 59 and for the decomposition ofhydrogen peroxide solutions by Mathews and Curtis lgO and byAnderson and Tayl0r.1~~~ What seems to be a significant contri-bution to the study of the mechanism of inhibitors in gaseousreactions, is the paper of Norrish 46 on the effect of ammonia on theinitial stages of the hydrogen-chlorine reaction, in which muchevidence is brought forward in favour of the reaction being a surfaceone.(viii) Xolvent and Velocity.No systematic investigation on these lines has been carried out,and the data which have appeared are not very conclusive. Andrichand Le Blanc 77 find the bromination of toluene in short ultra-violetlight to proceed less rapidly in pure toluene than in hexane solution,and still more slowly in ethyl acetate solution.As mentionedalready, they connect these changes with the nature of the absorp-tion curve and solvation of the bromine. Olivier l60 finds the acidchlorides of benzenesulphonic acid derivatives to be oxidised by airmore easily in ether than in chloroform, whilst there was no actionin carbon tetrachloride or in carbon disulphide. According tovon Euler,lG1 the photo-decomposition of the halogenoacetic acidsis far more rapid in ether than in benzene solution.Meyer andEckert obtain more rapid oxidation of dihydroanthracene disPHOTOCHEMISTRY, I9 14-1 925. 351solved in acetic anhydride or in ethyl alcohol than in methyl alcohol.Stobbe and Schmitt ,163 in studying for various wave-lengths theoxidation by air of ethyl iodide dissolved in carbon tetrachloride,benzene and alcohol, found complex differences, apparently depend-ing on internal light-filter action, or photosensitisation by liberatediodine, etc.Swensson 164 finds benzene, and still more, alcohol, toretard the bromination of xylene and toluene. In the latter case,he connects the effect with the fixation by the alcohol of hydrogenbromide, which is a positive catalyst. Lifschitz and Joffe 165have studied the changes of certain leuco-derivatives of the tri-phenylmethane series in ultra-violet light, and find more rapidreaction in alcohol than in ether or benzene. According to Plot-n i k ~ v , ~ ~ ~ the solvent has a considerable effect on the polymerisationof vinyl chloride. The best results are obtained in methyl alcohol.In carbon tetrachloride the reaction is rapid a t the start, whilst incarbon disulphide, nothing happens. In benzene, the results areabnormal.Mathews and Williamson 156 show that the rate offormation of p-chloroacetanilide from N-chloroacetanilide dependson the solvent, and moreover in the order ethyl alcohol > benzeneor glacial acetic acid > dilute aqueous acetic acid. Water hereplays an important rSZe. Winther 166 has directed attention to anapparent relation between rate of reaction and dielectric constantof solvent.(ix) Photochemical Stationary States.A system is said to be in a photochemical stationary state whenits final composition in a light field of constant intensity and qualityis different from the composition corresponding to thermodynamicequilibrium, and when, on cutting off the light, it changes, or tendsto change, to the thermodynamic equilibrium state.Prior to 1914,it was thought by some (e.g., by Coehn) that such stationary stateswere governed by the mass-action law, but this is now recognisedby all not to be so. Their formation and existence result from theopposition of two reaction velocities, but at least one of these is aphotochemical reaction velocity, not subject to the ordinary lawsof dark chemical kinetics.The possible types of stationary state which may occur have beendiscussed by Coehn and Stuckardt 78 and by Le Blanc.14 Coehnand Sieper 149 have investigated the case of carbon monoxide-oxygen-carbon dioxide, wherg the presence or otherwise of watervapour has a remarkable and profound effect. Coehn and Stuck-ardt 's have worked on the synthesis and decomposition of hydrogenchloride, bromide, and iodide, and on the effect of wave-length onthe stationary states.Le Blanc l4 has studied the complex case o352 ANNUAL REPORTS ON !E€E PROGRESS OF CHEMISTRY.sulphuryl chloride-sulphur dioxide-chlorine. The liberation ofiodine and the existence of a photo-equilibrium in insolated systemscontaining uranyl salts and hydriodic acid have been demonstratedby Hatt,lo5 and Rideal and Williams 25 have investigated a similarreaction where a ferric salt takes the place of a uranyl salt. Anumber of cases of stationary states set up under the influence ofultra-violet radiation have been reported in connexion with cis-and trans-stereois~merides.~~~~ 16* In one of these-the trans-formation maleic acid ZZ fumaric acid-the stationary state con-centrations found by Kailan 169 agree well with the values calculatedby E.Warburg 170 from his measurements of the energetics of thetwo component reactions. Other systems in which stationarystates have been described include phenylacetaldehyde and itspolymeride ; 171 the very complex case of hydrogen-oxygen-water-hydrogen peroxide examined by Tian ; a-phenylcinnamonitrile,bromine, and the addition product ; lZ5 leuco-compounds of thetriphenylmethane group, and the corresponding colouring matters ;lS5aqueous solutions of potassium nitrate in ultra-violet light.172 Inthe last example, the opposing dark reaction suggested isKNO, + 0 + KNO,.(x) Photochemical Extinction.Little need be said here. No cases have been reported, andinvestigators clearly do not expect to find them.The reason isthat, whereas the theory of electromagnetic absorption of light didnot contradict the possibility of the existence of such a phenomenon,the case is otherwise with the discontinuous theory of absorption,which sharply separates off light absorption and subsequentchemical happenings. On the older theory, photochemical extinc-tion or “chemical absorption” was looked on by some as exceed-ingly probable, as can be seen from a paper of Tian.9 It may beadded that Winther, in his 1909-1913 report: did not dismiss thepossibility in the case of endo-energetic or “ work-storing ” reactions.(xi) Photochemical Induction.Some new cases have been noted and are generally explained bythe former theories-the gradual destruction of an inhibitor or theformation of a positive catalyst by light.In some instances, thedark production of a photo-sensitiser has been shown to be respon-sible for the inception of the photo-reaction. Examples of the lasttype of action are furnished by nitrogen pentoxide decomposition,30and the oxidation of hydrogen iodide by oxygen in aqueous solu-tion,17 where the thermal production of nitrogen peroxide or ofI,- ions respectively is necessary before the photo-reaction caPHOTOCHEMISTRY, 1914-1926. 353commence. In the decomposition of hydrogen peroxide solutionsin presence of potassium ferrocyanide,173 the formation in light of aphoto-catalyst is clearly responsible. Destruction of a negativecatalyst (an ammonium salt) was shown to determine the inductionperiod in the oxidation of potassium oxalate by bromine in aqueoussolution,99 and a similar state of affairs probably exists in an aqueoussolution of formic acid containing added uranyl and vanadyl salts,which shows marked indu~tion.~05 Induction periods were alsonoticed during the reduction of carbonyl chloride by hydrogen,22the chlorine-sensitised union of carbon monoxide and oxygen,13the photolysis of oxalic acid, whether solid or in solution,93 thereaction between bromine and tartaric acid in aqueous solution,174and in the chlorination of certain aliphatic derivatives in carbontetrachloride solution.55 The papers of Norrish 46 and of Jones 72are of importance from the point of view of the mechanism involvedin inhibited chlorine reactions, and it is of interest that both intro-duce the surface of the vessel as a factor.Finally may be notedthat a curious “ negative induction ” is reported by Kornfeld andMiiller 42 in very sensitive hydrogen-chlorine mixtures.(xii) A f ter-eljects in Photochemical Reactions.These have been found to occur in the cases of the reactionbetween p-nitrosodimethylaniline and potassium ferrocyanide 175and the decomposition of hydrogen peroxide solutions in presenceof this saltJ173 in the bromination of toluene, hexane, and h e ~ t a n e , l ~ ~and the reaction between aqueous bromine and tartaric acid,174in the decomposition of Fehling’s solution in ultra-violet light 131and the transformation of N-chloroacetanilide into p-chloro-acetanilide.156 The suspected and sometimes proved cause of sucha phenomenon is usually the production of a “dark” catalystduring the photo-reaction.After-effects of a different nature, depending on the formationduring the photochemical reaction itself of an essential inter-mediate product, whose subsequent rate of reaction is sufficientlyslow to enable its presence to be detected after the cessation ofillumination, have been studied for the first time by Weigert andKellermann 38 in connexion with the initial stages of the hydrogen-chlorine reaction, and by D.L. Chapman,l06 who has followed upsome observations of Berthoud and Bellenot.99 Their furtherinvestigation promises to be of quite special interest,(xiii) Analogies between Photochemical and Other Types of ChemicalChange.Such comparisons are frequently, from a limited point of view,Boll 95 and Berthelot 1309 98 have directed of considerable interest.REP.-VOL.XXII. 354 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.attention to the analogy, from the point of view of kinetics, betweenthe effect of temperature in thermal reactions and frequency inphotochemical reactions, The Einstein Photochemical EquivalentLaw [see I11 (iii)] has been compared with Faraday's Law ofElectroly~is,l~~~ 8oy and frequency with decomposition voltage.98Baur has worked out in detail a whole theory of photochemicalchange on an electrochemical analogy, imagining the absorptionof light to polarise the molecule, with subsequent " electrolysis "and formation of " anodic " and " cathodic " prod~cts.l~~p 1 5 8 ~ 34s 179A comparison between the chemical action of the silent dischargeand that of light is made by E.Warburg.ls0 Berthelotgs andBancroft 181 have pointed out resemblances between photochemistryand fermentation reactions and contact catalysis respectively.111. E n e r g e t i c s.(i) 7'hermodyarnics and Photochemisiry.The irruption of the quantum theory into photochemistry hasprofoundly modified the point of view from which the energeticsof the subject is regarded. Before this event, many attempts weremade (particularly by Trautz, Weigert, and Byk) to treat photo-chemical problems by the aid of classical thermodynamics. Suchattempts had no great success, and the reason is obvious if thequantum theory be accepted.There is clearly a fundamentalincongruity between, on the one hand, the generalised, non-specificmethods of classical thermodynamics as applied, for example, t oa case of thermal equilibrium, and, on the other, the " activated "molecule resulting from an individual elementary photochemicalprocess, and capable, in virtue of its specific energy content, ofkinetic behaviour of a type quite different from that of the sur-rounding " un-activated " molecules. According t o Nernst andNoddack,lS2 the only valid application of thermodynamics to photo-chemistry is the decision as to whether or not a particular darkreaction is a possible one for the primarily formed activated molecule.(ii) Radiatioia Theory of Chemical Kinetics arid Photochemistry.Two main applications of the quantum theory to photochemicalenergetics can be distinguished, and others will doubtless come.The first, which has attracted much attention during the last fewyears, is based on the Radiation Theory of Chemical Reactivity,which is a combination of Planck's radiation theory with ideasfounded on thermodynamics and statistical mechanics and pre-viously put forward by Arrhenius and Marcelin.W. C. McC. Lewis,Trautz, and Perrin have independently developed forms of thistheory, and it is perhaps Perrin 183 who has most explicitly regardePHOTOCHEMISTRY, 19 14-1 9%. 355photochemical reactions as particular cases of thermal reactions,with a consequential similarity of treatment.It has already beenpointed out [Section I1 (i)] that a relative lack of success has inpractice attended this attempt a t assimilating photochemical withthermal reactions. Mention of a paper by Winther lS4 may beadded in this connexion. I n any case, the soundness of the whole" radiation " treatment of thermal reactions, particularly in itssimplest form, has been strongly challenged. Tolman 143 has putforward a modified form of the theory, based on statistical mechanicsand the quantum theory, and embracing photochemical reactions,whilst Weigert 185 has discussed similar modified views in a morequalitative way.(iii) The Photochemical Epuicalent Law.The other, and more important, quantitative application of thequantum theory is contained, of course, in the Einstein Law of thePhotochemical Equivalent.The Reporter has recently discussedfully certain aspects of this law, and, to save space, will refer readerst o this paper 178 for details, and deal with the subject here in outlineonly (see also The law itself in its simplest form, Vix.,that photochemical decomposition of a single molecule results fromthe absorption of a single quantum by this molecule, was formu-lated prior to 1914 and a thermodynamic proof given.1a2byc Adeduction of the relation on different lines appeared later,ld and madeit clear that the law only applies to the primary process of photo-chemical change, and, further, that this primary process is normally,not a disruption of the absorbing molecule, but an activation of thesame, followed by chemical reaction of the activated molecule.The activated form as described has the properties of a higherBohr state, and it is questionable whether the law will hold for othertypes of primary product, even supposing them to be formed,which also is doubtful.Much experimental work has been carried out during the lasttwelve years with a view to test the predicted relation betweenabsorbed energy and amount of photochemical change.Detailshave been given elsewhere,178 and mere reference will be made tothe papers of WarburgyS13 1809 1 8 6 y 17O Berthoud and Belle-notYg9 Bodenstein,13 Boll,95 Bonhoeffer,lG Book and Eggert,54Bowen,139 1 4 9 lS7 Buchi,l16 Eggert and Borinski,l28 Eggert andNoddack,lss Gruss,21 Hatt,lo5 Kornfeld,12? Kuhn,lo3, 134 NoddackY20P U S C ~ , ~ ~ ~ Rideal and Norrish,lsg Rideal and William~,~5 RudbergY1l7Vranek,lo4 Weigert and Scho11er,190 and Winther and Oxholt-H ~ w e .~ ~ A convenient and rational nomenclature in which toexpress the results has been drawn up by Warburg.809l 8 2 ~ l85).M 356 ANNUAL REPORTS ON THE PROGRESS Or CHEMISTRY.Work not included in the above list is summarised in the followingtable, where y signifies the quantum efficiency, or the number ofabsorbing molecules which have reacted per quantum absorbed.Reaction.Chlorophyll sensi-tisation of CO,assimilation.1,- sensitisation(aqueous solu-tion).of O,+HIDissociation ofNOC1.Dissociation ofC1,O (sensitiseclby C l d .H,+CI,.H2C,04 decom-position.O-C GH4(N02)*CH0 + O-C 6H4(NO)-C0,HAuthor.0.Warburg andNegelein.lO9Bowen.86Bodenstein andKistiakowski .I5Kornfeld andM~Iler.~,Anderson andRobinson.l22$ 9Weigert andBr0drnann.l 91Y .I n molecules ofCO,, 0.23 for0.66 p , 0.23 for0*578p, 0.20for 0 . 4 3 6 ~ .I n molecules ofHI, 6.5-83 for0.366 p.1-91-2.17 for2.0 for 0 . 4 3 ~ .0.47 p.u p to 2 . 8 ~ 1 0 4for 0.35.p.2 . 5 4 ~ lo4 for0.436 p.In molecules ofH2C204, 0.05for 0.20-0.28p ; 0.027 for0.365 p .0.0007 for0*20-0*30 p.0.40-0.61 for0.366 p ; 0.39-0.52 for0.405p; 0.34-0.65 for0.436 p.Remarks.Varies regularly withrate of absorption ofenergy by system,increasing as thisbecomes less. Forsame rate of energyabsorption, practi-cally independent ofA between 0.280 pand 0.436 p.Same for direct asfor ssnsitised re-action.Falls with decreasingpressure. Used lowpressures and Hgexcess.Ordinary gaseouspressures.For O.lN-H,C,O, +0.01M-U0,S04.Be-came less if [U0,S04]were decreased.Independent of con-centration.The actual values of quantum efficiency found vary enormously-in the period under review between 2.5-243 x lo4 for the hydro-gen-chlorine reaction 41, 42 and 0.0007 for decomposition of aqueoussolutions of oxalic acid.122 On the strict original interpretationof the law, the value unity should be got in every case, independentof wave-length and intensity of light, concentration, the presenceof other substances, and temperature. This is far from being thecase.The nature of the discrepancies found has been dealt withelsewhere.178 Here it will only be stated that y usually increaseswith frequency, often with concentration and with temperature(although only one case of the latter kind has actually been mea-~ u r e d ) , l ~ ~ and is frequently dependent on the presence of othePHOTOCHEMISTRY, 1914-1925. 357substances (positive and negative catalysts). In Kuhn’s experi-ments on ammonia decomposition,l03 he found y to decrease withincreasing homogeneity of light. The effect of intensity is not veryclear. Winther 192 has recently discussed cases in which thegreater the rate of absorption of radiation (which brings in intensityand concentration) the smaller is the quantum efficiency.In thehydriodic acid-oxygen reaction , sensitised by I,- ions, he considersthat only those I,- ions which absorb a single quantum are capableof causing the formation of iodine-those which take up more thanone quantum are inactive. On the other hand, the experimentalresults and the theory put forward byPringsheim,ll3* 11* in connexionwith the destruction of fluorescent dyes by light, indicate that thequantum efficiency should increase with the radiation density andthe concentration.It is not surprising that certain authors, more particularlyPlotnikov,l93 should have protested against the application of theterm “ law ” to the Einstein photo-equivalent relation. Its validitywithin well-defined limits, and the usefulness of the conception,cannot, however, be denied, and some of Plotnikov’s counter-proposals are distinctly retrograde.A juster appreciation iscontained in a paper by Nernst and Noddack.182 The first step ina photochemical reaction is undoubtedly the absorption of a singlequantum by a single molecule. This may or may not result in the“ activation ” of the molecule-the “ activated ” molecule, ifformed, may or may not undergo or take part in a secondarystoicheiometrical dark reaction. These two main causes of deviationfrom the Einstein relation will be considered in the next section ofthis Report.IV. Mechanism of Photochemical Change.(i) Preliminary.A consideration of this subject naturally divides itself into twoparts, one dealing with the mechanism of the primary photochemicaleffect, the second with that of secondary thermal reactions.Inrespect of both of these sub-divisions, we have reached a veryinteresting stage of development, and it seems likely that, in thenext few years, many of the questions a t present in the foregroundwill be substantially, if not completely, answered. The advancehere forecasted will primarily be due to an increased knowledgeof the mechanism of absorption of light by molecules and of itsconsequences, and to a more certain interpretation of the significanceof spectral data. Too many of the views put forward during thelast twelve years have taken little account of our existing store o358 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.knowledge on these subjects, and, as the latter increases, it is safeto prophesy that other views held to-day by many photochemistswill have to be jettisoned.(ii) The Primary Process.(a) Dissociation.-Probably influenced by the fact that, in theoriginal proof of the Einstein law,la the primary process taken asan example was a monomolecular dissociation, it was assumedearly that, provided that the absorbed quantum was greater thanthe energy needed to dissociate a single molecule (qo), such dis-sociation was bound to occur as an immediate result of absorption.Thus, Warburg suggested the following as primary reactions-f orozone formation, 0, -20 ; 186a for gaseous hydrogen bromide lSGband iodide 186~ decomposition, the monomolecular dissociation ofthe halogen hydride.Nernst 479 1773 lg4 proposed the reactionC1,+2C1 as the primary process in the photosynthesis of hydro-chloric acid, and this was concurred in by Gohring,48 Berthoud,50and Cathala.51 Bowen 85 treated the whole of the photochemistryof the halogen hydrides from the same point of view. Primarymonomolecular dissociations were also proposed for the photolysesof ammonia lo3 (into N + H, + H), nitrosyl chloride,s6 certainclasses of aliphatic and solutions of uranyl oxalate 116and potassium permanganate,lsg as also for the reactions of bromineor iodine with potassium oxalate 99 and of hydrogen with sulphurvapour (S, --+ 2S).31Stern and Volmer,195 in a very important paper, were the firstto point out that certain fluorescence phenomena (e.q., of iodinevapour) showed that a molecule could absorb and re-emit a quantumseveral times greater than corresponded to the energy of dis-sociation without being split up.Combining this fact with Bohr'sviews on light absorption, they asserted that the primary productof light action would invariably be an activated molecule with anatom in a higher quantum state (Bohr state). Collision withanother molecule (not yecessarily of the same nature, and, still less,activated) would always be necessary for chemical change. Suchchemical change might well be dissociation of the absorbing sub-stance-but as the result of a collision or secondary reaction.Warburg, who had previously 1 8 a applied Stern's conception of abimolecular reaction to cases where hv < qo (e.g., to ammoniadissociation), agreed that activation in the Bohr sense is probablythe immediate result of absorption, but would not exclude thepossibility of an immediately subsequent monomolecular dis-sociation.180 However, the views of Stern and Volmer haverecently gained general acceptance.For example, the first stagePHOTOCHEMISTRY, 19 14-1 925. 359of the hydrogen-chlorine reaction have been formulated by Coehnand Jung 3 9 ~ as (a) C1, + hv --+ Cl,’, ( b ) Cl,’ + C1, +Cl, + 2C1.This change in opinion is largely due to the work of Born andFranck,lS6 who have analysed the possible conditions under whicha molecule can decompose as a direct result of absorbing radiation,and come to the conclusion that a subsequent collision with anothermolecule of some sort or another is necessary. I n view, however, ofthe hydrogen-chlorine mechanism just mentioned, it is interestingto note that Franck,197 in a very recent paper, states that certaintypes of homopolar molecules, including the halogens, can bedirectly dissociated, into a normal and an excited atom, by absorp-tion of light of wave-length shorter than the long wave-lengthlimit of the continuous absorption band.I n the case of chlorine,this corresponds with the experimental result, already mentioned,found by W. Taylor.44(b) Actiz.ation.-In contrast with the clear idea of the ‘‘ activa-tion” of an atom afforded by the conception of the higher Bohrstate, with an actual loss of an electron as a limiting case, our viewson the nature of an “ activated ” molecule are relatively obscure.According to Volrner,l98 who found the electrical conductivity ofvarious photosensitive substances to increase on insolation, theactivation consists in a loosening or partial separation of valencyelectrons.The same view was put forward by B~denstein,~~ as amodification of his former theory 155 of complete electron separationas the primary process. It is also adopted by La~areflF,1~~ and hasbeen developed in recent years in a number of papers byWeigert,lg0J l g 9 1 83~ 7 3 ~ 185 who ascribes photochemical reactions insolid systems to an actual passage of an electron from one particleto another. Electron loss mechanisms are also postulated forspecific reacting solid systems by F a j a n ~ , ~ ~ ~ and by Moore andW.A. Noyes, j ~ n . ~ Baur’s 146~ 1583 34~ 179 view that an activatedmolecule is polarised or partially ionised has already been dealtwith. The limiting case of this conception-ionisation into posi-tive and negative ions-has not been proposed. Finally, War-burg 170 suggests that an activated molecule is one in which theconstituents (uncharged) have been widely separated as the resultof the absorption of a light quantum. If the separation becomescomplete, we have the case of dissociation already dealt with.enables us, in some measure, todecide between these conceptions. The essential result of theabsorption of a quantum of visible or ultra-violet light is to raise avalency electron to a higher quantum state.The internal con-figuration of the molecule is thereby changed, and there is, as asecondary result, an increase in the rotation and oscillation quan-Recent physical work ls6> 197360 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,tum numbers, coupled with, and determined by, the increase inelectronic energy. The change in rotational energy is small, andcan be neglected. If the absorbing molecule is heteropolar, e.g.,hydrogen bromide, the increase in energy of oscillation is alsoproportionately small, and there is no chance of a monomoleculardissociation (which would be into ions, and not into atoms) takingplace. If the absorbing molecule is homopolar, the state of affairsis somewhat different. With a certain type of linking (by van derWaals's forces, as Franck puts it), it is possible for the molecule totake up large amounts of oscillation energy, so much so, thatdissociation into an excited and a normal atom eventually results.The halogens, as bas been seen above, probably come under thiscategory.With another type of homopolar molecule, linking byshared electrons, of which hydrogen and oxygen form examples,although oscillation energy can be very much increased by lightabsorption, there is no chance of a monomolecular dissociationinto atoms.It thus appears that, in general, the " electron-loosening "mechanism of Stark (compare Luther's very similar ~iews),'~bsupported, as we have seen, during the last twelve years by Volmerand others, describes the state of a photo-activated molecule betterthan the other conceptions put forward by photochemists.Baur'spolarisation idea corresponds, qualitatively only, to what happens(in addition) in heteropolar molecules, and Warburg's conceptionof the partial separation of neutral constituents can be applied(in addition) t o homopolar molecules. In any case, these activatedmolecules represent unstable systems, with a strong tendency topart with their energy of activation.Activation does not, of course, necessarily follow absorption.The increase in energy brought about by the absorption of thequantum may be too small to activate the molecule for the parti-cular reaction. This will be so if the absorbing molecule is originallyin too low a quantum state.This aspect of the subject has beentreated by T ~ l m a n , l * ~ ~ who has shown the connexion between thetemperature coefficient of the reaction and the proportion of mole-cules which will be in a position to react as the result of quantumabsorption. Weigert lS5 also has laid emphasis on the importanceof the initial energy state of the absorbing particle. If the reactionis bimolecular, the total heat of activation can, in principle, becontributed to by the two reacting molecules. Bodenstein 201considers the bromination of toluene from this point of view.H. S. Taylor and Marshall4 show that, in the mercury-sensitisedreduction of carbon monoxide by hydrogen, the carbon monoxideis probably not ActivatedPHOTOCHEMISTRY , 1914-1 925.361(c) Life of Activated Molecules.-This is obviously an importantquestion, as collision between an activated molecule and some otherone is normally necessary before reaction of any kind can tlakeplace. The nature of an activated molecule being as explained,it follows that its life must be of the same order as that of a higherBohr state, i.e., 10-7-10-8 second (for a list of the determinations,see 40). Noddack 2O and Griiss 21 calculated for particular casesvalues of the order of 10-9-10-7 second. The negative results ofLe Blanc and Volmer and others,657 G6, 67 on the insolation ofchlorine before allowing it to come into contact with hydrogen, arein qualitative agreement, and, as Warburg 180 has pointed out, areevidence against the assumption that chlorine atoms are the primaryproduct of light action in this case.There is, however, one class ofreactions the kinetics of which appears to indicate the existence ofactivated molecules of comparatively long life, i.e., reactions photo-sensitised by halogens .202 Franck, Nernst and others have expressedthe opinion lZ8 that-halogens must be capable, in some way or other,of stabiliaing a quantum taken up in a higher Bohr state. Possiblythe explanation may be a metastable halogen molecule, of the typepostulated by Franck and Grotrian 203 to explain the long-livedfluorescence which can be excited in mercury vapour under certainconditions. There may also be mentioned here a paper by To1man,204which contains calculated examples of durations of higher quantumstates amounting to as much as one second.(iii) Fate of Acticated Molecules.(a) Deactication by Radiation.-We have seen that molecules of acertain particular kind can (probably) break up spontaneously asthe result of the absorption of a sufficiently large quantum. I nother cases, however, if they do not, during their life period, en-counter another molecule, collision with which will bring aboutchemical reaction, they will lose energy, and revert t o the un-activated condition.Cases in which this lost energy appears asradiation have been much studied by physicists (e.g., resonanceradiation and fluorescence in rarefied gases) and similar conceptionshave been introduced to explain de-activation in photo-sensitivesystems. The more energy lost in this way, the smaller, of course,will be the photochemical utilisation of the originally absorbedenergy.Triimpler 205 found that oxalic acid, which quenches thefluorescence of uranyl salts far more strongly than does formic acid,undergoes photolysis in a uranyl salt mixture much more easilythan does the latter. Pringsheim 1139 114 thinks that the majorityof activated molecules tend to lose their energy by fluorescence,and that, for chemical action to result, the absorbed quantum must3l362 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.be comparatively large, or there must be a favourable probabilityfactor, involving a high light intensity or close proximity of twoactivated molecules.in order to explain the difficulty with regard to the longlife of the activated molecule in the halogen-sensitised reactionsreferred to above, suggests that chlorine molecules are capable ofisochromatic fluorescence or resonance radiation, and that absorbedlight is constantly being re-emitted and reabsorbed by other mole-cules until finally transformed into heat (translational energy) orchemical energy. Such resonance radiation is not observed onaccount of the weak absorption, and therefore weak fluorescence, ofchlorine.(The “ van der Waals” type of linking assumed byFranck lg7 for the chlorine molecule would perhaps render suchresonance radiation possible.) Weigert explains in this way theabsence of the Budde effect in dry chlorine, and Ludlam206 putsforward an identical view of the absence of the same phenomenon indry bromine.Winther 1849 8> 1459 2079 110 supposes the activated molecule of aphotosensitiser, such as chlorine, zinc oxide, or the I,- ion, to lose itsenergy in the form of short ultra-violet radiation (i.e., the moleculeof the sensitiser transforms the absorbed radiation up to a higherfrequency), and that it is the absorption of this radiation whichbrings about the sensitised reaction.He accounts for the frequentretarding action of oxygen by its absorption of this radiation, andsuggests that induced (dark) reactions are caused by similar absorp-tion of short ultra-violet chemiluminescent radiation resulting fromthe primary reaction.(b) Deactiration by CoZlisiox.-If an activated molecule, duringits life-period, strikes another molecule, a number of things mayhappen. Of these, the most frequent is the degradation of its energyof activation into heat (energy of translation).Physics furnishesa number of well-known examples. Thus, the resonance fluores-cence of iodine or of mercury becomes weaker if the pressure of thevapour itself is increased, or if foreign gases are admixed; this isascribed to collisions between inactive molecules and activatedmolecules before the latter have had time to radiate, the energy ofactivation being transformed by collision into kinetic energy oftranslation.?08 The fact that absorption lines in gases becomebroader at high pressures and are very generally broad in solutionis regarded as evidence that the absorbing molecules are being“ damped ” by collision with neighbouring parti~les.~g (Thequantum theory substitutes for this impact damping an effect due tothe fields of neighbouring atoms on the configuration and energy ofthe excited electron orbit in the activated molecule.82) WarburPHOTOCHEMISTRY , 19 14-1 925.363ascribes to this damping the low quantum efficiencies frequentlyobt'ained in reactions in solution. The degree of activation conferredon the absorbing molecule by the absorbed quantum would besufficient, if it could be utilised, to bring about the chemical change-but, before it can be utilised, it is reduced below the critical levelby the interaction of solvent molecules. WeigertY209 in a number ofpapers, has insisted on the importance, from this point of view, oftaking into account the orientation and the whole environment ofan absorbing molecule in a photochemical system-the absorbedquantum is very frequently only partly utilisable.There are conditions in which such collisions between activatedmolecules and others do not appear to cause energy degradation, or,if they do, it is negligible in amount-the halogen-sensitised reactionsalready referred to.Thus, in the bromine-sensitised transformationof maleic ester to fumaric ester in carbon tetrachloride solution,128there must be several thousand inactive encounters between activ-ated Br2' molecules and carbon tetrachloride molecules before aneffective one takes place. Or, alternatively, a single collision onlycauses a very slight energy loss.According to Stern and Volmer,lg5the greater the electron affinity of the unactivated molecule, thegreater will be the energy dissipation on impact. As has been seen,it appears necessary, in the case of the halogens, to assume apeculiarly stable type of activated molecule.(c) Collisions with Acceptors.-Before, however, an activatedmolecule radiates or loses sufficient of its energy by interaction withneighbouring particles, it may collide with an " acceptor," i.e., amolecule which, in circumstances, may be capable either of reactingwith the activated molecule, or of itself alone undergoing chemicalchange as a result of the encounter, or, by giving an opportunity forthe quantised energy content of the activated molecule to adjustitself to new molecular configurations, of permitting the latter t oundergo chemical change.By no means all such encounters seemto be effective in causing chemical reaction. Thus, unproductivecollisions between activated and normal ammonia molecules,accompanied by energy dissipation, may account for the lowquantum efficiency observed in ammonia decomposition.1866 Thesame type of phenomenon, complicated by the presence of othergases, appears in the deozonisation of ozone.126, 1 5 2 9 13'$ 141 Thereis then, from this point of view, no sharp distinction betweenacceptors and non- acceptors.But there can also be collisions which, whilst ineffective from thechemical point of view, and causing the deactivation, complete orpartial, of the original activated molecule, do not result in thisenergy of activation being completely degraded ; it is simply passedM* 364 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.on, perhaps with loss, from the one molecule to the other, the latterbecoming activated.(If the two molecules are identical in chemicalnature, the result is the same as an elastic collision, or one nearlyso.) From the point of view of the quantum theory, the result ofsuch an impact is simply an extreme case of the degradation ofenergy by collision considered in the last section.Our knowledge of this type of collision we essentially owe toFranck. In a series of papers appearing from about 1913 onwards,he studied the interactions between moving electrons and gas atoms,and was able to show that, on collision, the kinetic energy of theelectron was changed, in accordance with the quantum theory,into energy of activation of the gaseous atom (First Type RayZessCollision) 210 If the kinetic energy of the electron were less than theamount corresponding to the one quantum necessary, the collisionswere perfectly elastic.The next step was taken by Klein andRosseland,211 who showed the necessity, in such circumstances, ofSecond Type Rayless CoEZisions, in which an atom in a high B o bstate, by encounter with an electron, completely loses its energy ofactivation, which is turned into energy of translation of the electron.Franck212 extended these views so as to embrace collisions withtransfer of quantised energy between activated and unactivatedatoms or molecules of the same or of different kinds, and appliedthe conception to the transfer of energy in photochemical reactions,particularly photosensitised reactions.Thus, the photosynthesisof water by visible light in presence of chlorine 56 will proceed byprimary activation of the chlorine, collision between activated Cl,‘molecules and oxygen molecules, resulting in deactivation of theformer and activation of the latter, and, finally, interaction betweenthe acceptor, hydrogen, and the activated 0,’ molecules. It hasalso been suggested that such secondarily activated 0,’ moleculesmay play a part in deozonisation,202 and in the reaction betweenoxygen and trichlorobromomethane,21 both sensitised by chlorine.In the former of these reactions, there must either be such raylesstransfer of energy between activated and normal chlorine molecules,or else elastic collisions.The beautiful work of Kautsky and his colleagues213 forms anindirect confirmation of the above views, in that they have shownthat chemiluminescence and the induced chemiluminescence whichthey discovered are the exact reversed counterparts of photochemicaland sensitised photochemical reactions.When chemical reactions result, there are several cases to dis-tinguish.The activated molecule may undergo isomeric change, asin the transformation of maleic into fumaric a~id.1‘~ Or it maydissociate. Thus, processes such as Cl,’ + C1, +2C1+ C12,39e HI’ PHOTOCHEMISTRY, 1914-1 925.365HI -+H + I + ~ 1 , 1 3 7 N O C ~ + NOC~ -+ NO + ci + NOCI, s,’ +S, --+ 2s + S,, etc., may be supposed to follow the appropriateactivation processes. There is no necessity for the second moleculeto be of the same nature as the first, its function being merely toallow of adjustment, in accordance with quantum mechanics,lg6~of the energy changes involved in the activation and subsequentchemical reaction. Thus, in the hydrogen chloride and hydrogensulphide syntheses, the Cl,’ and S,’ molecules could equally well bedissociated by collision with hydrogen molecules.On the other hand, it may be the activated molecule which willdissociate the normal, or in some other way change it chemically.For the four equations as written above, these two possibilities are,of course, indistinguishable as far as chemical result is concerned.I n other cases, particularly in photosensitised reactions, it is quiteclear that it is the normal molecule which is decomposed.Thus, wewould have Cl,‘ + SO,CI, -+ C1, + SO, + C1,.I n the photosyntheses of hydrogen sulphide and hydrogen chlorideby short wave-length ultra-violet light, and, therefore, with highlyactivated S,’ and C1,’ molecules as primary products, the reactionsS,‘ + H, -+ S, + 2H and (31,’ + H, --3 C1, + 2H 39C are con-ceivable. One of the best known and simplest examples of this isthe dissociation of hydrogen in short wave-length ultra-violetlight as sensitised by mercury vapourj3 where we haveHg + hv _3 Hg’.Hg’ + H, --+ Hg + 2H.I n some sensitised reactions, the high quantum efficiency obtainableshows that the activated molecule of the sensitiser is only slightly,and not completely, deactivated as the result of a single impactwith the acceptor-the quantum is, as it were, distributed over alarge number of molecules of the acceptor.128Finally, we have fhe case where the two molecules react togetheron collision (Stark’s thermophotochemicaZ reaction Thismechanism has been proposed in many cases-e.g., NH,’ +NH3+N, + 3H2 ; 1866 HBr’ + HBr -fH, + Br, ; lg5 0,’ + 03---+30, ; 126C1,O’ + C1,O 4 2C1, + 0,.15 Collisions between activated andnormal molecules of the chloroplatinic acids 95 and of potassiumnitrateY8l between Cl,’ and trichlorobromomethane 182 and between(21,’ and H, molecules 473 49 are regarded as the stage following lightabsorption in the respective reactions concerned.(d) Reaction Chains.-The summary of current views on themechanism of photochemical change so far given does not accountfor cases in which y is much greater than unity.Such reactionsare, without exception, exothermic. The combination of hydroge366 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.and chlorine and the decomposition of hydrogen peroxide solutionsare extreme cases. The products a t the instant of their formationcontain, not only the energy of activation originally absorbed, butalso the liberated energy of reaction, and the suggestion that thisenergy store might in some way bring about further decompositionwas an obvious one, and was made a good many years ago.Severalviews have been taken as to how this is brought about. Baly 373 214thinks that the energy excess is radiated by the product in the formof infra-red quanta of frequencies which coincide with absorbingfrequencies of the original photosensitive molecules. More of thelatter are thus activated. Anderson and H. S. Taylor 159 speak ofthe originally absorbed quanta being emitted by hydrogen peroxidemolecules during decomposition, and being reabsorbed by othermolecules. Kornfeld 215 has shown that no radiation is liberatedduring the combination of carbon monoxide and chlorine (a reactionin which y is high) which will pass through quartz and, after itspassage, bring about the combination of carbon monoxide and oxy-gen, although this reaction is sensitised by chlorine in a mixturein which some carbonyl chloride has already been formed.Thisexperiment is interesting in connexion with Winther's suggestions[Section IV (iii) a].The generally favoured explanation of the high quantum yield,however, assumes the formation of reaction chains, a conceptionfirst introduced by Bodenstein lS5 to account for the big quantumyields in the hydrogen-chlorine reaction. These reaction chainsusually fall into one or other of two classes. In the one, the primaryprocess has, as one of its products, a free atom or group. Thisenters into reaction with a molecule of one of the substances originallypresent, forming another group or atom as a reaction product, whichacts similarly, and so on, the chain of reactions being brought to anend by the gradual combination of the free atoms or groups with oneanother.I n the other type of chain, an energy-rich activated mole-cule of one of the products is supposed to activate a molecule of oneof the reactants by collision, this activated molecule then forminganother activated molecule of resultant, and so on. There is thusa succession of rayless transfers of energy (Franclc tramfers). Thechain in this case will come to an end by reason of a gradual dissipa-tion of energy during collisions, either during the legitimate impactwith the molecule of reactant, or during impact with other, non-reactive, molecules.The best known example of the " atomic " chain is that suggestedby Nernst *' t o account for the hydrogcn-chlorine reaction.It isc1, + hv + 2x1.Cl + H,+ HC1+ H.H + C12+ HC1 + C1, etc.PHOTOCHEMISTRY, 1914-1925. 367finishingby2C1+C12; 2H+H,; H + Cl+HCl. Thechlorin-ation of methane could be described similarly, with substitution ofCH,, CH,Cl, etc., groups for H atoms. Berthoud and Bellenot 99propose a chain of the natureI + C204-- + I- + C,04-C204- + I, 4 2C0, + I- + I, etc.,for the iodine-potassium oxalate reaction. Recently, H. S. Taylor216has suggested the following mechanism for the reduction of ethyleneby hydrogen in presence of mercury, a reaction discovered by himin conjunction with Marshall : *Hg’ + H, -+ 2H (Cario and Franck reaction 3,€3 + C,H4 -3CzH5C2H, + H, --+C,H, + H, etc.I n such chains, each of the steps subsequent to the primary reactionmust be a spontaneous change, and exothermic. I n this connexion,however, it must be remembered that the products of reaction willbe in possession of a portion of the heat of reaction of the last linkin the chain in which they have taken part-partly possibly asquantised energy of activation, partly doubtless as energy of trans-lation.Further, the molecules that enter into each step will differfrom one another in energy level. Consequently, a thermochemicalcalculation is not in a position to declare definitely that a certainstep is impossible because it is (thermodynamically) endothermic.An example is furnished by the reaction Br + H, 4 H + HBr,which is certainly endothermic in this sense, a fact which wasadduced as a reason why a H,-Br, mixture is practically inertphotochemically a t the ordina,ry temperat~re.1~~ Bodenstein andLutkemeyer 107 have, however, shown, almost beyond doubt, thatthe reaction is an essential stage in the photosynthesis of hydrogenbromide which can be effected a t higher temperatures.Examples of the “ rayless transfer ” type of chain are furnishedby the similar mechanisms suggested by Bodenstein 47 and by D.L.and M. C. C. Chapman49 for the hydrogen-chlorine reaction, in-volving activation of chlorine molecules by HCl’ and H2C12’ mole-cules respectively, and by Kornfeld 127 for hydrogeii peroxidedecomposition (complex steps involving formation and disappear-ance of activated H+’ ions and 0’ atoms).The most direct evidence bearing on the actuality of reactionchains of one sort or another is contained in the work of Weigert andKellermann,38 who demonstrated the fact that hydrogen andchlorine continue combining together for a short period after thelight is cut off.Recently, “ rayless transfer ” reaction chains havebeen introduced into the kinctics of thermal reactions 217 as 368 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.possible explanation of a well-known difficulty concerning rates ofreaction and activation. This is not the only recent instance whichcould be given of the close relations now existing between photo-chemical and dark kinetics.107~ 1379 1 4 1 9 218(e) Egect of Water Vapour.-Mention must finally be made of thebearing of recent work on the part played by water in the union ofhydrogen and chlorine and on the mechanism of the chain reactionto be adopted.Stern and V ~ l m e r , ~ ~ ~ taking the view that collisionis necessary before an activated molecule can break up, suggestedthat the first stage in the reaction might beCl,’ + H,O --+ HC1+ OW: + C1followed by C1+ M, +H + HC1, etc., as in the Nernst chain. Thevelocity of reaction would be independent within wide limits of[H,O], as was found by Bodenstein and Water was thuspostulated as an essential constituent in the reaction, and therewas definite, though not undisputed, evidence to show that this wasthe case. Coehn and Tramm 39a confirmed the necessity for waterwhen using visible light, and Coehn and JungJsgc assuming theimpossibility of the (probably endothermic) reaction C1 + H, -+HC1 + H, which was implicit in Stern’s mechanism, suggested thefollowingCl,’ + c1, + c1, + 2c1.H + C1, -+- HC1 + C1 1 etc.Weigert 73 (and later Bowen 85) criticised this mechanism asinvolving water in the chain, in which circumstances [H,O] wouldcertainly be of importance. Weigert put forward the view that an“ adsorption complex ” of H,-Cl,-H,O is necessary for the initiationof the primary process, before the chain sets in (earlier workers hadimagined such a complex) and that the presence of the water enablesa smaller quantum to start the reaction than would otherwise be thecase.Bowen, assuming the Mernst chain, suggested that thewater acted by virtue of a surface action on the walls of the vessel,preventing the union of hydrogen atoms to molecular hydrogen, areaction which would end the chain.Coehn’s mechanism was criticised by CathalaYs1 who pointed outthat the relative numbers of impacts which would take place betweenchlorine atoms and water molecules on the one hand, and betweentwo chlorine atoms on the other, in experiments quoted by Coehnand J ~ n g , ~ ~ d in no way corresponded with the numbers necessitatedby the high quantum efficiency obtained. He suggested that thefunction of the wate? molecule, as an electric dipole with a largeC1+ H,O -+ HC1+ OHOH + H, -+ H,O + PHOTOCHEMISTRY, 19 1P-1925. 369stray force field, was to induce greater chemical reactivity in thosemolecules within its sphere of influence.Norrish 469 220 reinforcedCathala's criticism of Coehn's mechanism, and in addition, pointedout a fallacy in the former's own argument. Like Bowen, hesuggested that the effect of the water was exerted on the surfaceof the reaction vessel, and supported his argument by a consider-ation of the details of the experiments of Coehn and Jung. Hisview is that a water-chlorine complex, such as ,>o<g;, isformed on the surface of the vessel, but is so structurally weakenedby adsorption that light can bring about its decomposition intowater molecules and chlorine atoms, the Nernst chain then following.Chapman lo6 accepts the evidence of the necessity of the presenceof water, rejects Bowen's suggestion as to the part played by thelatter, and proposes a chain mechanism of a new (addition product)type which may be represented as follows :HCl,' + H,O --+ :i>O<zc1 cl>o<g + H, -+ c"l>o<E + HC1g>O<E + C1, + g:>O<z + HC1 etc., etc.Here the subject, which is very much under discussion, can beleft, and the Report concluded.A.J. ALLRIAND.REFERENCES15 Ann. Physik, 1912, [iv], 37, 832. l b Ibid., 1912, [iv], 38, 881. 1c J .Physique, 1913, 3, 277. Id Verh. deut. physikal. Ges., 1916, 18, 318. 2 2.wiss. Photochem., 1914, 14, 19; A., 1915, ii, 199. 2. Physik, 1922, 11,161; A., 1922, ii, 809. 4 H. S . Taylor and A. L. Marshall, J. 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ISSN:0365-6217    

DOI:10.1039/AR9252200333

出版商:RSC    

年代:1925

数据来源: RSC