摘要:

ANNUAL REPORTSPROGRESS OF CHEMISTRY.ON TElANNUAL REPORTSF. W. ASTON, M.A., D.Sc., F.R.S.8. RARRATT, H.A.W. L. BnAGG, F.R.S.H. Y. A. BRISCOE, D.Sc.J. A. V. BUTLER, M.Sc.J. E. COATES, O.B.E., D.Sc.J. c. DRUMMOXD, D.Sc.ON THEU . A. ELLIS, M.A..J. J. Fox, O.B.E., D.Sc.W. E. HAWORTH, DSc., P1i.D.T. A. HENRY, D.So.C. I<. INGOLI), D.Sc., F.R.S.13. J. PAGE, M.B.E., B.Sc.PROGRESS OF CHEMISTRYF O R 1926.ISSUED BY THE CHEMICAL SOCIETY.&ommittre ofChairman : N. Y. SIDQWIH. B. HAKEI:, C.B.E., D.Sc., F.R.S.IL C. C. BALY, C.B.E., F.R.S.H. BASSETT, D.Sc., Ph.D.k’. G. DOWNAN, C.B.E., M.A.. F.R.S.H. W. DUDLEY. O.B.E., M.Sc., l%D.U. R. EVANS, M.A.J. J. Fox, O.B.E., D.Sc.C. S. GIBSON, O.B.E., &LA.R. W. GRAY, O.B.E., Ph.D.A. J.GREENAWAY, F.I.C.T. A. HENRY, D.Sc.C. K. ISGOLD, D.Sc., F.R.S.H . V, A. nRIWOE:, D.Sc.I~uhlitatiotr :CK, M.A., Sc.D., F.R.S.H. KING, D.Sc.H. MCCOMB~E, D.S.O., M.C., D.Sc.W. H. MILLS, Sc.D., F.R.S.T. 8. MOORE, 1RI.A.. I:.Sc.G. T. MOXGAN, O.B.E., D.Sc., F.R.S.1;. J. P. OKTON, M.A., F.R.S.J. R. PARTINCTON, M.H.E., D.Sc.5. 0. PHILIP, O.B.E., D.Sc., F.R.S.R. H. PICKARD, D.Sc., F. R.S.T. S. PRICE, O.B.E., D.Sc., F.R.S.F. L. PYMAN, DSc., F.R.S.R. ROFIIW~OX, D.Sc,, F.R.S.J. F. THOKPE, C.B.E., D.Sc., F.R.S.VOl. XXIII.LONDON:GURNEY & J A C K S O N , 33 PATERNOSTER ROW, E.C.4.1927PRlhTED IN QAEAT BRITAIN BYRICHARD CLAY % SONS, LIMITED,BIJNOAY, aumo'oLCONTENTS.PA01GENERAL AND PIZYSICAL CHEMISTRY. By J.E. COATES, O.B.E.,D.Sc., and J. A. V. BUTLER, M.Sc. . . . . . . 11INORGANIC CHEMISTRY. By H. V. A. BRISCOE, D.Sc. . . . 49ORGANIC CHEMISTRY :-Part ~.-ALIPHATIC DIVISION. By W. N. HAWORTH, DSc., Ph.D. . 74Part II.-HOMOCYCLIC DIvIsioN. By C. K. INGOLD, DSc., F.R.S. . 112Part III.-HETEROCYCLIC DIVISION. By T. A. HENRY, DSc. . . 160ANALYTICAL CHEMISTRY. By J. J. Fox, O.B.E., DSc., and B. A.ELLIS, M.A.. . . . . . . . . . . 186BIOCHEMISTRY. By J. C. DRUMMOND, D.Sc., and H. J. PAGE, M.B.E.,B.Sc. . . . . . . . . . . . . 209CRYSTALLOGRAPHY. By W. L. BRAOO, F.R.S. . . . . 267ASTON, M.A., D.Sc., F.R.S.. . . . . . . . 280SPECTROSCOPY. By S. BARRATT, B.A. . . . . . . 296SUB-ATOMIC PHENOMENA AND RADIOACTIVITY. By Fa WTABLE OF ABBREVIATIONS EMPLOYED IN THEd5BREYIATED TITLE.A ., . . .A.Abhandl. Xennt.'KohieAnter. Choa. J. , .Amer. J. Physiol. .Amer. J. Sci. . .Anter. Rev. TuberculosisAnal. R s . Quim. .Analyst , . . Annalen . I .Ann. Appl. Baol. .Ann. Bat. . . .Ann. C h h . . .Ann. Chiin. anal. .Ann. Chim. Appl. .Ann. Physik . .Ann. I'hysiqzre . .Ann. Roports . .Ann. Ilcp. Apppl. Chem.Arch itnl. Mzol. .Arch. Phwm. . .Arch. Sci. phys. nat. .Arkiv Kent. Min. Geol.Aslrophys. J. . .Atti 11. Accad. Lincei .B. . .Bakt. Abha&. . .Rer. . .Ber. Deut. bot. Ges.Miochem. J. , .Biochcm. Z. . ,BOl. @a%. *Brgnwtof Chem. .Bull. Acad. Sci. Rozwzainc.Bull. int. Acnd. Polonnise .BuZl. Sci. Pharm. . ,Bull. Sac. chim. , .Bull. Soc. chim. Belg. .REFERENCES.JOURNALAhstracts in Journal of the Chemical Society.British Chemical Abstracts,* Section A.Gesanimelte Alhandlungen zur Kenntnis der Kohle.Ariierican Chemical Journal.American Journal of Physiology.America11 Journal of Science.American Review of Tuberculosis.Anales de la Sociedad EspmBla Fisica y Quimica.The Analyst.Jnstos Liehig's Annalen der Chamie.Annals of Applied Biology.Annals of Botany.Anuales de Cliimie.Aunales de Ohimie analgti ue sppliqide Al'Industrie,Annali di Cliiniica Applicata.Annalen der Physik.Annales de Physique.Annual Reports of the Chemicrtl Society.Annual Ileiiorts on the Progress of Applied Chemistry.Archives italieiiues de Biologie.Archiv der Pharmazie.Archives des Sciences physiques e t naturelles.hrlriv for Kemi, Mineralogi och Geologi.Astrolbhysicnl Journal.Atti (Kendiconti, Memorie) della Reale AccademiaNaxionale dei Lincei, classe di scienze fisiclic,niateniatiche e natunlli, Roma.British Chemical Abstracts,* Section B.Centralnnstalten f8r f8rsokovasendet p% jordhruk-somr%det Bakteriologiska avdelringen (Germantmsl.).Borichte der Dentschen Chemischen Gesellschaft.Herichto der Deutschen botanischcn Gesellschaft.The Hiochaniical Journal,Biochemische Zeitschrift.Botanical Gazette.Brennstoff Cheniie.Bulletiu de la Section Scieiitifique de l'hadkmieRoumaine.Bulletin international de 1'Acadhmie Poloneiae desh I'Ayriculturs, r?.la Plarniacie et h la Riologie.Sciences.Bulletin des Sciences Pharmacologiques.Bulletin de la SociBtA chimiqua de France.Bulletin de la Socikth chimiqne de Belgiquc.* The rear is not inserted in rsferenaefl to 1926TABLE OF ABBREVIATIONS EMPLOYED IN THE REFERENCES. viiABBREVIATED TITLE.Bull.Soc. Chim, b i d .Cwncgae Inst. bl‘ashiiiglonCeElulaseeAem. . .Chem. awl I d . . .Chem. Listy . .Chem. News . .Chem. IZetirzcs . . Chem. Weekblad .Chm. Ztg. , ,Chem. Zentr. , .Compt. rend. . ,ona apt. wad. SOC. ~ $ 0 1 .JOURNAL.Bulletin de la Soci6t.d de Chimie biologique.Carnegie Institiite of Washington Publications.,, . Cellulosechemie. . Chemistry and Industry. . Cliemick6 Listy proVEdu a Prilmysl. Organ de la‘‘ Ceskb chemickA SpoleEnost 1lro Vedu aPrKnlysl.” . Chemical News., Chemical Review. . Chemisch Weekblitd.. Chemiker Zeitung., Chemisches Zentrnlblatt. . Comptes rendus hebdcmadaires des SQances de, Cornrites rendus hebdoliiadaires de Shances de I:&l’Acad6mie des Sciences.Socihth de Biolopie.Can~pt. rmd. Traw. Lab. Comntes rendas des Travnns du Loboratoirc Carls-C i r M e r g . . . .Conit.22 Univ. Agr. Expf.Sfa. Memoir . . .Dezels. Landw. Presse . IQas- 16. Wasserfach . .Qazxstta . . . .Oiorn. Chim. Id. AppL .Hob. Chim. Acta . .Ind. E?kg. Chem . . .J . . . . I .Jahresb. . , . .J. Agric. Res. , . ,J. Agrie. Sci. , , .J . Anur. C h m . SOC. . .J. Anier. Need. Assoe. , .J . Amer. Pharm. Assac. .J. Amer. SOC. Agron. .J . Amcr. Water JVa~1.sAssoo. . . . ..T. Bad. . . .J. Bzochem i Japan) . .J. Biol.Chem. . .J. Canada Med. k s a e . .J . Chem. Education . .J. Chim. phvs. .J. Call. Agrio. Hokkaid;Imp. Univ. I . .J. Dept. Agric. K ~ u s ~ ~ Luniv. . . . J. Exper. i k d . . . . J. Franklin Inst. . .J. Ben. Physiol. . . .J. Gidian Chem. S’oc. . ,J. Opt. Sac. Amer. . .J. Pharm. Cliim. . .J. Physical L‘lkem. . .J. Phy;riaI. . . .J. Physique. , . .J . Phys. findirm . . J. PO^. H o d . Sci. . .J, pr. Chem. . , . J. Buss. Phys Chem, Sac. IJ . Soc. Chem. Ind. . .berg.Station Memoirs.Cornell University Agricultiirnl ExperimentDeu t,sche Land wirtscli aftlielie Pr e sse.Gas- ond Wasserfnch.Gazzetta chimica italiana.Giornale di Chimica Industriale ed Applicata.IIelvatica Chimica Acta.Industrial and Engineering Chemistry.Journal of the Chemical Society.Jahresbericlit iiber die Fortsuhritte der Chemic.Journal of Agricultural Research.Journal of Agricultural Science.Jonrnal of the American Chemical Society.Journal of the American Mediral Association.Journal of the Aniericiin Pharmaceutical Associat’ion..Journal of the American Society of Agronomy.3onrnal of the Ameiican Water Works Association.3ournal of Racteriology.Jonrnal of Biochemistry (Japan).Journal of Biological Chemistry.Journal of the Canadian Medical Association.Journal of Chemical Education.Journal de Chimie physique.Joiiriirtl of the College of Agriculture, HokkaidoJournal qf t h e Dapartnieot of Agricultnre, IiyushuImperial University, Japan.University.Journal of Experimental Mediciiio.Journal of the Franklin Institute.Journal of General Physiology.Quarterly Journal of the Indian Chemical Society.Journal of the Optical Society of America.Journal de Pharmacie e t de Chimie.Journal of Physical Chemistry.Journal of Physiology.Journal de Physique.d o u i ~ ~ a l de Physique e t Ic Radiiun.Journal of Poiiiology and Horticultriral Science.Journal fur praktische Chemie.Journal of the Physical and Chemical Society ofJournal of the Society of Chemical Industry.RussiaVai TABLE OF ABBREVLQTIONS EMPLOYED IN THE REFERENCES.ABBREVIATED TITLE.J.Soc. Chon. Japan . ,J . Soc. Dyers Col. . .J. Text. Inst. . . .mim. Woch. . .Koll. Chm. Beih’eftte . .Kolloid-2. . . . ,Landzo. Jahrb. . . .Landw. Jahrb. Schwei: .Landw.Versuehs-Stat. .Me&. K. Vetenakaprakad.Memo Coll. Sei. Kyoto, .Mem. Mancheater Phil. Soc.Mikrockein. . . .Mitt. tuisa. tech. Arb. Be-publ. (Rtcss.) . . ,Nonatah. . . . .Naturiuiss . . . INew York Agric. ESP. Stat.Nobd-Imt. , I .P . . . . . .PflJger’s Archiv. . ,Pharm. Weekblad . ,Pharm. Zentr. . . .Phzl. Mag. . . .Phil. Trars. , ,Physical Rev. . . .Phyrikal. 2. . I Proc. Camb. Phii. Soe. .Proc. Imp. Aend. Tokyo. .Proc. K. Akad. IVt$enseh.Proc. Nat. Acad. Sci. . . PTM. Physical Soc. . ,Proc. Roy. Soe. . , ,Proc. Soe. Exp. Biol. Ned. .Ree. trav. chim. . . .Rocz. Chem. . . .9. Afr. J. Sci. . . .Sci&ifiC Agrie. . .am:. Papers Id. Phys.Chcm. Rrs. Tokyo . .Sei. Proc. Roy. Dnblin 9oc.ScL Xep.T8haku Imp. Univ.Silmngsbcr. .&idelberg.Akad. Wiss. . . .Sitzzmgsber. Preuas. Akad.Wiss. Berlin . . .906. Seient. Fennicae . .Soil sci, . . .Stahl u. E&en . . .AmsterdamJOURNAL.Journal of the Chemicnl Society of Japan.Kwagaku Kwai Shi.)Journal of the Society of Dyers and Colourists.Journal of the Textile Institute.Illinische Wochenschrift.Kolloidchemisohe Beihefte.Rolloid ZeiBchrift.Lsndwirtschaftliche Jahrbiicher.Landwirtsol~aftliclie Jahrbiicher Scbweize.Die Landwirtschaftlichen Yersuchs-Etationen.Meddelanden frdn Kunglig-VetenskapsakademieaeNobel-Institut.Memoirs of the College of Science, Kyoto ImperialUniversity.Memnilo and Proceedings of the Manchester Literaryand Philosophicnl Society.Mikrorhcmie.Mitteiluugen iiber wissentschaflich-technischen Arbeiti i i der Repuhlik (Kuss.).Monntshefte fur Chemie und verwandte Theile andererWissenschaften.Die Naturwissenschaften.New York Agricultural Experiment Station Bulle-Proceedings o f the Chemical Society.Archiv fur die gesanite Physiologie des Menechen und(Nippontinq.d.London.Physical Review.PhyRikalische Zeitschrift.Proceedings of the Cambridge Philosophical Society.Proceedings of the Imperial Academy of Japan.Koninklijke Akademie van Wetenschappen te Amster-dam. Proceedings (English version).Proceedings of the National Academy of Sciences.Proceedings of the Physical Society of London.Proceedings of the Royal Society.Proceedings of the Society for Experimental Biologyand Medicine.Recueil des travaux chimiques des Paye-Bas s t de laRelgique.Roczniki Cheinji organ Polskiego TowarzystwaClieniicznego.South African Journal of Science.Scientific Agriculture.Scientific Papers of the Institute of Physical andScientific ProceediiigR of the Royal Dublin Society.Science Reports, TBhoku Im rial University.Sitzungsberichte der HeiGberger Akademie derSitzungsberichte der Preussiechcn Akademie derAota Societatie Scientiarum Fennicae.Soil Science.Stahl und Eisen.Chemical Rerearch, Tokyo.Wissenschaften.Wissenschaften 211 BerlinTABLE OF ABBREVIATIONS EMPLOYED IN THE REFERENCES. ixABBREVIATED TITLE.r3vemk Rein.Tidskr. . .Tram, Avikw. Elsctrocheirb.soc. . . 9 ,T~a7i.s. Furaday Soc. . . i"rans. Roy. 8oc. Cmada .~~krainc &em. J. . .Vwh. deczlt. physikrcl. GES. ,1 Viss. Yerof. 8iemna- Ko,w.X. anal. Chum. . I .2. angeut. Chm.. . .X aiwrg. Chon. . . .3. Chm. Plbarnk. . .X. duuts. G a t . Gcs. . .Z. Elektrochcm. . . I Z. Krist. . . . .3. +?mi~z, DIOUJ. . .2. Physik . . . .%. physikal. Chew&. . .3. ph ysika2. eheii 1. Uict c r r.2. phyS.Wl. Chcm. . ,JOURNAL.Svensk Kemisk Tidskrift.Transactions of the American ElectrochemicalSociety.Transctctiona of the Faradiay Society.Transactions of the Royal Societv of Canada.Ukrainian Chemical Joiirnal. "Verhandlungen der deutschen phyeikalischen Gesell-Viusenuchaftlinhe Verofleutlichungen BUS demZeitschrift fur analytische Chemie.Zeitschrift fur angewandte Chemie.Zeitschrift fur anorganische und allgerneine Chemia.Zeitschrift fiir Chemie und Phwmecie (ErlenmeyerZeitschrift der deutschen Geologischen Geaellschaft.Zeitschrift fur Elektrochemie.Zeitschrift fur lirystallogra hie.Zeitschrift fiir Pflaneenern&rung und Diingung.Zeitschrift fiir Physik.Zeitschrift fur physikalischa Chemie, StdcbiometrirZeihchrift fur den physikaliachen und chamieciisnHoppe-Seyler's Zeitvclirift fur pl~ysiolosgichs Chemie.schaft.Siemens-Konzern.und Lewinstein).und Verwandtschaftvlehre.Unterricht.A

ISSN:0365-6217    

DOI:10.1039/AR9262300001

出版商:RSC    

年代:1926

数据来源: RSC

摘要:

TABLE OF ABBREVIATIONS EMPLOYED IN THE REFERENCES. ixERRATUM:ANNUAL REPORTS for 1925.Page LineI73 6* f o r d C tetra-ecetyl ” read ‘‘ tetra-cetyl.”-* From bottom.A

ISSN:0365-6217    

DOI:10.1039/AR9262300009

出版商:RSC    

年代:1926

数据来源: RSC

摘要:

ANNUAL REPORTSON THEPROGRESS OF CHEMISTRY.GENERAL AND PHYSICAL CHEMISTRY.No attempt is made to report progress in more than a few fields.The output of work on solutions of electrolytes warrants a con-tinuation of last year’s Report on this subject, and a section onreaction velocity in such solutions is added. References to opticalactivity and mutarotation seem desirable as a sequel to the 1924Report. Subjects not recently dealt with are entropy, chemicalconstants, and electrification a t surfaces.The Third Law of Themnodynamics and the Entropies ofSolids and Liquids.Perhaps the most fundamental of physico-chemical problems isthe relation between the maximum work and the correspondingtotal energy change of a chemical reaction. A knowledge of thisrelation in general would enable all kinds of chemical equilibriato be calculated from thermal data alone (heats of reaction atsuitable temperatures, and the heat capacities of substances fromabsolute zero up to the highest temperature for which the equi-librium is to be calculated).The relation may be stated mostsimply in terms of the entropy change in the reaction by meansof the equation AA - AU = - T . AS, or by the analogous equationAF - AH = - T . A#. Here, AU is the total-energy increase inthe reaction, AH = AU + P . AV the “ heat content ” increase(i.e., the heat absorbed in a reaction a t constant pressure), AAthe maximum work done on the system, and AF = AA + P . AVthe free-energy increase of the system. The problem thereforereduces to a consideration of the entropy changes in reactions.The concept of entropy as a quantity which can be definitelyevaluated is chiefly due to G.N. Lewis and G. E. Gibson, whomade the first systematic tabulation of the entropies of element8and compounds.1 The entropy of a solid a t a temperature T,referred to its entropy at absolute zero, is given by the integrall J . A m r . Chem. Soc,, 1917, 39, 2564; A., 1918, ii, 2912 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.AS? = (C,/T) I dT, where C, is its heat capacity; and theentropies of liquids and gases are obtained by summing similarexpressions for all the heat changes required to bring them fromthe solid crystalline state a t absolute zero to the given temperature.The entropy change in a chemical reaction involves, in additionto the entropies of the substances concerned (referred to absolutezero), a knowledge of the entropy change in the reaction a t absolutezero, since ASP = A#,, + XAST.The third law of thermo-dynamics as formulated by Nernst was equivalent t o the state-ment that the entropy change in all reactions of (' condensed ''systems (solids or liquids) is zero at the absolute zero of tempera-ture. In 1920, Lewis and Gibson showed that this could not betrue when supercooled liquids or solid solutions are involved, andthey proposed to restrict the law to crystalline bodies, stating itthus : I ' If the entropy of each element in the crystalline form betaken as zero a t absolute zero, the entropy of any pure crystal a tabsolute zero is zero, and the entropy of any other substance isgreater than zero." E.D. Eastman3 has since argued that thereis a complete series of gradations from a perfectly crystalline sub-stance to t,he haphazard arrangement in an amorphous solid, andthat complicated systems of a low order of symmetry may haveappreciable positive entropy. L. Pauling and R. C. Tolman, how-ever, deny this and, in a statistical investigation of the entropy ofsupercooled l i q ~ i d s , ~ conclude that the entropy of a perfect crystala t the absolute zero is not dependent on the complexity of theunit of crystal structure: The third law may be tested by com-paring the entropy change in a reaction as deduced from equilibriummeasurements [ASP = (AH - A F ) / T ] with the entropy change(ZAA';), calculated from the heat capacities.Lewis and Gibson,in their 1917 paper, showed that the available data, of somewhatlow accuracy, supported the law (in its more general form). In1920, G. E. Gibson, W. M. Latimer, and G. S. Parks found thatthe thermal entropies of formation of formic acid and urea werein good agreement with the values obtained from equilibriummeasurements. In 1922, Lewis, Gibson, and Latimer drew upa revised table of entropies and demonstrated, in a number ofcaaes, close agreement with the requirements of the law. T. J.Webb has obtained a further confirmation in the cases of hydrated1'J . Amer. C%m. SOC., 1920, 42, 1529; A . , 1920, ii, 585.Ibid., 1924, 48, 39; A , , 1924, ii, 143.Ibid., 1926, 47, 2148; A ., 1925, ii, 952.Ibid., 1920, 42, 1633; A., 1920, ii, 686.6 Ibid., 1922, 44, 1008; A , , 1922, ii, 471.J . Phyaical Chm., 1926, aS, 816; A . , 1926, ii, 867QENERAL AND PHYSICAL CHEMISTRY. 13cadmium chloride (CdCl,,26H2O) and cadmium iodide. H. L. J.Biickstrom 8 investigated the change aragonite + caleite for thesame purpose, but found a difference, which he ascribed to an errorin the specific-heat curve of calcite at low temperatures.Further work has been done to confirm the conclusion thatsupercooled liquids and solutions have greater entropy than thecorresponding pure crystals, The first test of the point by Gibson,Parks, and Latimer 9 with solutions of ethyl and propyl alcoholwas inconclusive. R. Wietzel 10 found that there is probably anentropy difference between amorphous and crystalline forms ofsilica a t absolute zero.G . E. Gibson and W. P. Giauque l1 showedthat supercooled liquid glycerol almost certainly has a greaterentropy than the crystalline form. Now F. Simon and F. Lange lahave reinvestigated these cases and find in the case of silica anentropy difference of 0-9 -J= 0.3 unit, and in the case of glycerol4.6 & 0.3 units, a t absolute zero.The third law, in the form given it by Lewis and Gibson, i6being used to determine the free energies of substances whichcannot be conveniently determined by equilibrium measurements.Thus G . S. Parks and K. K. Kelley 13 have determined the entropiesof the oxides of magnesium, calcium, aluminium, and (ferric) ironand of magnetite a t 25" by heat-capacity measurements and haveobtained therefrom values of the free energies.Similar measurementshave been made with zinc 0xide.l' The free energy so determinedis in good agreement with the values obtained by direct methods,for which data are in this case available. The free energies of thefollowing organic compounds have been determined by the samemethod : Methyl, ethyl, and n-butyl alcohols 1 5 ; isopropyl alcohol,acetone, ethylene glycol, acetic acid, and palmitic acid Is; tert..butyl alcohol, mannitol, erythritol, and n-butyric acid 17 ; n-propylalcohol, ethyl ether, and dulcitol.18The entropy of a solid substance could evidently be calculatedfrom its complete specific-heat equation.Whilst the specific-heatequations for solids a t low temperatures account well for the forma J . Atmr. C h m . SOC., 1925, 47, 2432; A., 1925, ii, 1162. ' I b i d . , 1920,42, 1542; A., 1920, ii, 586.la 2. anwg. Chem., 1921, 116, 7 1 ; A., 1921, ii, 504.l1 J . Amr. Chem. Soc., 1923, 46, 83; A., 1923, ii, 124.la 2. Physik, 1926, 38, 227; A., 1000.Is J . Physical Chem., 1926, 30, 47; A., 232.C. G. Maier, G. S. Parks, and C. T. Anderson, J. Arne?. Chcm. Soc., 1926,G . S. Parks, ibid., 1925, 47, 338; A4., 1025, ii, 491.G. 8. Parks and K. K. Kelley, !bid., p. 9089; A , , 1925, ii, 949.G. S. Parks and H. M. Huffrnan, ibid., p. 2788.48, 2564; A., 1210.l 7 G. M. Parks and C. T. Anderson, ibid., 1926, 48, 1506; A., 78414 ~ N U U REPORTS ON THE PROGRESS OP CHEMISTRY.of the curve, an exact calculation of entropy on the same basis isnot yet feasible.Attempts have been made to find empirical equations for thoentropies of solids a t a given temperature. According to Latimer,19the entropy of an atom in a solid is a function of its mass, M , andof the constraints by which it is held.At temperatures a t whichthe specific heats have reached the equipartition value the con-atraints are held to be the same, and Latimer found that theentropies of 16 salts a t 25" were given by the sum of terms, S298. =$R log M - 0.94, for all the atoms in the salt. This equationdoes not apply to the metals themselves. E. D. Eastman20 hasattempted to introduce it term depending on the constraints of theatoms and has found that the equationwhere V is the atomic volume and p the compressibility, givesapproximately the entropies of many metals.Recently R. M.BufEngton and W. M. Latimer 21 have made some accurate measure-ments of the coefficients of expansion of solids a t low temperatures.Their measurements confirm the relation of E. Gruneisen 22 that theratio of the specific heat to the volume coeEcient of expansion ofa substance is nearly independent of the temperature. They usethis ratio (CP/3a, where a is the linear coefficient of expansion) forexpressing the " constraints " of different substances and findthat the equationgives the experimental entropies of a number of metals. It alsoapplies to salts when M is replaced by the geometrical mean ofthe weights of the ions.Szgr = +R log M + R log p312/V + 42.1,Smg $R log H + H log V - +R log (CP/3ti)r= 180.+ 26.5The Entropies of Gmes and Dissolved Substances.Simple thermodynamical considerations lead to the followingequation for the entropy X of ti mol. of perfect monatomic gas, attemperature T and pressure p :0. Sackurz3 showed that the constant So is proportional solely toM3/2, where M is the molecular weight of the gas, and the equationbecomesS = ~ R l o g T - R R ~ g p + S o . . . . , (1)S = $22 log T - R log p + SR log M + [SJo . . . (2)I* J. Arne?. Chem. soc., 1921, 43, 818; A,, 1921, %, 380.20 Ibid., 1923, 45, 80; A . , 1923, ii, 124.* I Ibzd., 1926, 48, 2305; A., 1088.9 1 Ann. Physik, 1908, Gv], 28, 211; A., 1908, ii, 563.23 Ibid., 1911, [iv].36, 958; A . , 1912, ii, 145GENERAL AND PHYSICAL CHEMISTRY. 15where [S], is a universal constant. H. Tetrode, and later S a ~ k u r , ~ ~evaluated this constant from statistical considerations, obtainingthe expressionwhere k is the gas constant per molecule (= R / N ) , r is the electroniccharge and h is Planck’s quantum constant. G. N. Lewisz5 hasalso made a calculation of [S], on the basis of his theory of “ ultimaterational units.” The expression obtained (in the same notation) is[S], = R log { ( 2 ~ ) 3 ’ 2 k 6 ‘ 2 ~ 5 ’ 2 / h 3 } , . . . . (Ba)where c is the velocity of light. The values of these expressionsare - 2.30 (Tetrode) and - 2.63 (Lewis). Experimental valuesare not known with sufficient accuracy to permit a decision betweenthe two expressions, but theoretical considerations appear to favourthe Tetrode expression.z6R.C. Tolman 27 determined the entropies of a number of gasesindirectly from vapour-pressure data and, except in a few casesin which a large extrapolation had to be made, found good agree-ment with (2). Lewis, Gibson, and Latimer28 showed that infour cases for which direct thermal data were available (He, A, Cd,and Hg vapours), there was remarkable agreement between thetheoretical and experimental values. It may be noted, however,that the data were not sufficiently accurate to distinguish betweenthe two values of [S], above. More recently, W. H. Rodebushand A. L. DixonZ9 have determined the entropies of vapoursof zinc and lead by vapour-pressure measurements and findgood agreement with the theoretical values.Similar measure-ments with sodium vapour by Rodebush and T. de Vries30 showonly moderate agreement. Tolman has also shown3’ that if anatmosphere of electrons be considered as a monatomic gas, itsentropy, as nearly as it can be computed from various thermionicdata, agrees with the theoretical value.The molecules of polyatomic gases may possess rotational andvibrational energy which must be taken into account in calculatingtheir entropies. Tolman 32 made the assumption that the entropy24 Ann. Phyaik, 1912, 38, 434; 1913, 40, 67; A., 1913,iL 128. 0. Sterngave a kinetic deduction of the same equation, Physikal. Z., 1913, 14, 629.* $ Physical Rev., 1921, ii, 18, 121.p e Compare H.C. Hicks and A. C. a. Mitchell, J . Amer. Chem. Soc., 1920,17 Ibid., 1920, 42, 1185; A., 1920, ii, 468.Ibid., 1925, 47, 1036; A . , 1925, ii, 492.ao Ibid., p. 2488; A., 1925, ii, 1142.* I Ibid., 1921, 43, 1692; A., 1922, ii, 18.Ibid., 1920, 42, 1185; A., 1920, ii, 468.48, 1520; A., 784.** Loc. cit., ref. (6).LOC. cit., raf. (27)16 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of any gas is the sum of the entropy of a perfect monatomic gasunder the same conditions and the entropies of its rotational andvibrational energies. These are given by ~2'Cr,d log T, where C, =C,, - 4R is the difference between the actual heat capacity of thegas and the value for a monatomic gas. Only in one case, that ofhydrogen, of which the heat capacity drops to the value for amonatomic gas above its boiling point, can this equation be appliedto experimental data.Attempts have been made to evaluate this integral by theoreticalcalculations of the rotational and vibrational energies.In theca0e of a diatomic gas, it appears that only rotational energyneed be considered. H. C. Urey has to evaluatethe rotational energy of such gases by the uEie of an expressionof F. Reiche34 which gives the rotational energy of a moleculein a state characterised by two quantum numbers n,, n2 ast = P(n, + n2)/8x12, where I is the moment of inertia of themolecule. The relative numbers of molecules in different quantumstates are given by statistical equations ; I is obtained from themaxima A,, h2 of the band spectrum by the classical equationI = k T [ h , h , / x c ( ~ , - A,)],. Similar methods are applied to sym-metrical polyatomic gases, e.g., methane. R.C. Tolman andR. M. Badger extended this method,35 and recently H. C. Hicksand A. C. G. Mitchells6 have made a careful study of hydrogenchloride from the same point of view. Using '' half quantum "numbers to specify the possible rotational states of the moleculethey find the value of j C r d log T between 0" K. and 298" K. to be6.75. The value of the total entropy obtained by adding this tothe corresponding entropy for a monatomic gas agrees well withthe experimental figure.Another method of dealing with rotational energies is by theuse of an equation37 deduced by 0.Sackur, H. Tetrode, andothers :Good agreement was found in this case.S = SR log T + +R log M + R log V + S+R log I , , , , + S, . (3)$8 J . Amer. Chem. SOC., 1923, 46, 1446; A , , 1923, ii, 633.Ann. Phyaik, 1919, [iv], 58, 667.J . Amw. Chem. Soc., 1923, 46, 2277; A . , 1923, ii, 830.34 J . AWT. Chem. SOC., 1926, 48, 1620; A., 784.'7 0. Sackur, Ann. Physik, 1913, [iv], 40, 87; A . , 1913, ii, 128; H. Tetrode,ibid., 1912, [iv], 38, 441: L. Schames, PhyhkuZ. Z., 1920, 21, 38; A . , 1920,ii, 172; R. C. Tolman, J . Amer. Chem. Soc., 1921, 45, 866; A., 1921, ii, 381;P. Ehrenfest and V. Trkal, PTOC. K . Akad. Wetemch. Amsterdam, 1920, 23,162; A., 1920, ii, 738; Ann. Phyaik, 1921, 66, 609.Compare R. C.Tolrnan, Phy8iCd Rev., 1923, ii, 22, 470.LOC.cit., ref. (26)GENERAL AND PHYSICAL CHEMISTRY. 17where I,, I,, I , are the moments of inertia. This equation cannotbe employed directly, owing t o lack of information about momentsof inertia. Urey expressed- his results in terms of this equation,substituting the moments of inertia obtained by the methoddescribed above. Latimer and Eastman 38 have given variousempirical equations for the entropies of diatomic gases.A further important advance in this field has been made byW. M. Latimer and R. M. B~ffington,~~ who have calculated forthe f i s t time the entropies of inorganic ions in aqueous solution.Knowing the entropies of the solid salts and the heat-content andfree-energy changes on solution, it is possible to calculate theirentropies in solution.The entropies are obtained for a “hypo-thetical molar concentration,” i.e., they are obtained from dataat very small concentrations and converted to the correspondingvalues at unit (molar) concentration on the assumption that thesolution remains ideal. Although expressed as entropies in a(hypothetical) molar solution, they refer therefore to the propertiesof ions a t great dilutions.It is only possible to obtain in this way the sum of the entropiesof the ions of the salts; but relative values for individual ions,referred to the entropy of the hydrogen ion as zero, are readilyobtained and are sufficient for most purposes. The authors furthercalculated the entropies of the ions in the gaseous state by theequation for perfect gases and thus obtained values for the entropiesof solution of gaseous ions.The values so obtained exhibit aremarkable parallelism with the energies of solution of the gaseousions.@ Further, when these entropies were plotted against theatomic radii of the ions as deduced from the crystal measurementsof W. H. and W. L. Bragg, a linear relationship was discovered forions of each charge. It is concluded that the entropy of solutionof gaseous ions is to a high degree a function solely of the size andcharge of the ion.The relative entropies of ions in aqueous solution can be appliedt o a great variety of thermodynamical problems. A number ofexamples are given in this paper, and in a further paper W. M.Latimer 41 has used the data to calculate the normal potential ofthe fluorine electrode.3 8 LOC.cit., refs. (19) and (20).so J. Amer. Chem. Soc., 1926,48, 2297 ; A., 1102. K. F. Herzfeld attemptedto calculate electrolytic normal potentials on the assumption that the entropiesof dissolved ions are the same as in the gaseous state at the same concen-tration (Ann. Physik, 1918, [iv], 56, 133; A., 1918, ii, 289). Later he reversedthe calculation and estimated from normal potentials and solubilities, the“ bound energy ” (= TJS) of ions relative t o the silver ion (2. Ekktrochem.,1922, 28, 460; A , , 1923, ii, 12).u 1%’. 31. Latimer, ibid., 1926, 48, 1234; A., 648. 41 Ibid., p. 286818 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.Chemical Constants.The so-called '' chemical constants," or integration constantsof the Clausius vapour-pressure relation, d log pjdT = AH/RTe,are intimately connected with the entropies of the correspondinggases.Since investigations in the two fields have been carriedon by different groups of workers practically independently, it isconvenieiit to deal with them separately, but the results in onefield have obvious bearings on the other.In the earlier attempts t o evaluate chemical constants by Nernstand his school, empirical equations for the variations of heatcapacities with temperature were employed which were wide ofthe truth a t low temperature^.^^ The true integration constantis obtained by giving AH its value AH = AHo + I".Cp. dT,where AC, is the difference between the heat capacities of gasand solid, whenceAH,, + /cAC~ dT .dT + i, RT2 RT log p = -and accurate heat-capacity data a t low temperatures are requiredto determine the integration constant i. For a perfect gas havingconstant heat capacity C, down to absolute zero, iR + C, =So - SgS, where S,, is the entropy constant of the gas [equation(l)] and Xos the entropy of the condensed phase a t absolute zero.According to the Nernst heat theorem, S,,s is zero 42a; hence, for amonatomic gas, the Sackur-Tetrode calculation [referred to theabove equation (2a)l leads to the value i = log ( ( Z m ) 3 ' 2 k S / 2 / h 3 } .Using gram-molecular weights and converting to common loga-rithms we obtain the chemical constant C = C, + log,, M , whereC, is a universal constant numerically equal to - 1.589.A.C. G. Egertona collected the available experimental datafor ten substances (based on measured vapour pressures except intwo cases) and obtained a weighted mean - 1.596 f 0.008, ingood agreement with the theoretical value. I?. Simon,M however,using values of C determined for 14 elements, found considerabledeviations which appeared to increase with increasing heat ofvaporisation. Notable divergences are exhibited by the elementssodium and potassium, as first observed by R. Ladenburg andR. Mink~wski.~~ Recent investigations have confirmed these68 Compare A. C . G . Egerton, Phil. Mag., 1920, [vi], 39, 1 ; A., 1920, ii, 84.4Zo According to Lewis and Gibson this must be limited t o crystalline solids,43 Proc.Physical SOC., 1925, 37, 75; A,, 1926, ii, 277.u 2. physikal. Ohem., 1924, 110, 572; A , , 1925, ii, 98; ibid., 1926, 123,4 5 2. Physib, 1921, 8, 137; A., 1932, ii, 191.see ref. (2).404; A., 1103. Compare K. Wohl, ibid., 1924, 110, 166; A., 1926, ii, 98OENBRAL AND PHYSICAL CHEMISTRY. 19discrepancies. F. Simon and W. Zeidler 46 have redetermined theheat capacities of these elements a t low temperatures and obtainvalues of C greater than the theoretical values by + 0.52 f 0.23(Nrt) and + 0.33 0.32 (K). W. Edmondson and E g e r t ~ n , ~ 'whiIst criticising certain of these calculations, have substantiallyconfirmed this result.I n the calculation of the Sackur-Tetrode expression, identical"quantum weight factors" are assigned to solid and vapourphases.If the identity of these factors is not assumed a moregeneral expression is obtained, viz., i = log {gg/g, . ( Z ~ r n ) ~ ' ~ k ~ ' ~ / h ~ ) where gg and gs are the weight factors for the gaseous and solidstates. The nature of the quantum weight factors has been dis-cussed by A. Einstein,48 0. Stern,49 W. Schottky,50 and R. H.F0wler.~1 If gg/g8 = 2, i will be greater than the Sackur-Tetrodevalue by log 2. I n the case of the alkali metals, according toSchottky there is spectroscopic evidence for g, = 2, and if g, = 1the experimental values are approximately accounted for.In the last equation, the term g, refers to the solid (or con-densed) phase. It implies a finite entropy of the condensed phaseSoa = R log g,. A. Eucken and F.Fried 52 have attempted todetermine whether solids have finite entropies a t absolute zeroby comparing the integration constants, ig, of the equilibrium-constant equation of a number of gaseous reactions, with Xi, thealgebraic sum of the vapour-pressure constants of the substancesconcerned. These two quantities are only identical if all valuesof Sos are zero. They find differences outside the experimentalerror in most cases. These would be covered by a zero entropy of& R log 2, but the data are not sufficiently precise for a quantitativeagreement to be made out. Fried 63 has made a further test ofthe same point by determining electromotively the free energyof reactions of the type MO + H, = M + H,O (M = Hg, Pb, or2Ag), and comparing it with calculated values involving the chemicalconstant of hydrogen.It is claimed that the results indicatefinite zero-entropies. It may be observed that it is not entirelyclear that these calculations are always referred to the solids ascondensed phases.Little progress has been made in accounting for the chemical46 2. physikal. Chem., 1926, 123, 383; A., 1103.4 7 Proc. Roy. SOC., 1927, [A], 113, 620, 633.4a Verh. deut. physikal. UM., 1914, 16, 820.4p Ann. Phyeik, 1916, [iv], 49, 823; A., 1916, ii, 379.6 1 Phil. Mag., 1923, [vi], 44, 1, 497; 1926, [vii], 1, 845; A,, 663.62 2. Physik, 1924, 29, 36; A , , 1926, ii, 97.53 2. physikal. Chem., 1926, 123, 406; A., 1105.Physikal. Z . , 1921, 22, 1 ; A., 1921, ii, 179; ibid., 1932, 23, 9, 44820 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.constants of polyatomic molecules.The following equation forthat part of the chemical constant which is dependent on rotationalenergy, i, = log (8x2~kfh2u), where f is the geometrical mean ofthe moments of inertia of the molecule and u a symmetry factor,has been obtained in a number of ways 54 [compare equation (3)].A. Eucken, E. Karwat, and F. Fried55 determined the chemicalconstants of a number of gases and compared them with the valueobtained by adding the above term to the “ monatomic ” constant,using optical values of I and ignoring the factor u. The resultsshowed no concordance, which might be ascribed to the absenceof the factor a. Mention may be made of recent determinationsof chemical constants of the following : Chlorine,66 bromine,57iodine,ss and hydrogen halides.Sg No satisfadtory agreement hasbeen obtained between the values (between which large discrepanciesoften occur) and the theory.In the Seckur-Tetrode calculation, the quantum theory isimplicitly applied to the translational motions of gases, whilst incalculations of chemical constants it is assumed that that part ofthe heat capacity which depends on the translational energy is aconstant down to the absolute zero. W.Nernst 6o employed adegradation theory according to which the heat capacities of gasesfell off a t low temperatures in the same way as do those of solids,and obtained a value i = log ((2m)3’2k5’2/&3}, which is almost indis-tinguishable numerically from the Sackur-Tetrode value.Theconditions which must be fulfilled by a gas the heat capacity ofwhich falls off to zero at absolute zero have been examined byK. Bennewitz,61 whilst the difficult question of the applicabilityof quantum theory to the translational motions in gases has beendiscussed by several authors.62 F. I. G. Rawlins 63 has recently64 Ref. (37). Also M. Saha and R. Sur, Phil. Mag., 1926, [vii], 1, 279;A., 234; K. SzBll, 2. Physik, 1926, 36, 292; A., 570.6 6 2. Physilc, 1924, 29, 1 ; A., 1925, ii, 98; ah0 A. Eucken and E. Karwat,2. phyeikal. Chem., 1924, 112, 467; A., 1924, ii, 820.6 6 R. R. S . Cox, Proc. Cantb. Phil. SOC., 1926, 22, 491; A., 1025, ii, 645.6 7 R. Suhrmann and K. von Liide, 2. Physik, 1924,29, 71 ; A., 1925, ii, 96;sn K.Jellinek and R. Uloth, ibid., 161, 157; A., 463.00 Z. Ekktrochem., 1916, 22, 185; A., 1916, u, 469.e2 A. Einstein, Sitzungsber. Preuss. Akad. Wisa. Berlin, 1924, 261 ; 1925, 3,18; A., 1925, ii, 405, 624; M. Planck, ibid., 1925, 49; A., 1925, ii, 495; A.Schidlof, Arch. Sci. phys. nat., 1924, [v], 6, 281, 381; A . , 1925, ii, 483;ibid., 1926, [v]. 8, 5 ; A., 463; E Schrodinger, Sitzungaber. Preusa. Akad.Wias. Berlin, 1925, 434 ; A+, 1926, ii, 951 ; Physzkd. Z., 1926, 27, 95; A,,463.K. Jellinek, 2. anorg. Chem., 1926, 152, 16; A,, 569.F. I. G. Rawlins, Trans. Fwaday Soc., 1926, 22, 233; A., 1087.2. phyrikal. Chem., 1924, 110, 725; A , , 1925, ii, 97.Proc. Physical Soc., 1916, 38, 176; A., 567GENERAL AND PHYSICAL CHEMISTRY, 21summarised some aspects of the present state of knowledge ofspeoific heats a t low temperatures and chemical constants.Solutions of Electrolytes.In continuation of the1925 Report,l the following investigations for the purpose of furthertesting the Debye-Huckel theory of strong electrolytes may benoted.The limiting law for tervalent ions has been confirmed bysolubility measurements of [Co(NH3) a)"'[Co(CN)6]"' in sodiumchloride solutions.2 The effect of the dielectric constant of themedium has been confirmed by measurements of the activitycoefficients of hydrogen chloride in aqueous glycerol ~olutions,~and by similar measurements in sucrose solutior~s.~ The effect oftemperature as predicted by the theory has been confirmed bysolubility measurements of silver iodate a t 75".The theory hasbeen tested in certain non-aqueous solvents.has studied the freezing-point depressions of some salts in aceticacid and in liquid ammonia, obtaining results which are mainlyin agreement with the theory. Similar measurements with cyclo-hexanol as solvent show good agreement with the equations.'In his extension of the theory to concentrated solutions, it willbe remembered that E. Huckel attempted to take into account theeffect of varying dielectric constant of the solutions, and, on theassumption that the dielectric constant varies linearly with the ionconcentrations (i.e., D = Do - S c ) , he found that the correspondingterm in the expression for log f was approximately proportionalto the concentration.8 G.Scatchard9 has tested this equationfor aqueous and alcoholic solutions of hydrogen chloride, and findsthat it is in good agreement with the data up to 1M. H. S. Harned 10has studied the activity coefficients of hydrogen chloride in con-centrated chloride solutions with the same object, and finds thatthere is " remarkable agreement between the observed resultsand the general theory of Debye and Huckel. In fact, nothingAnn. Report, 1025, 22, 27.J. N. Bronsted and N. J. Brumbaugh, ,J. Amer. Chem. SOC., 1026, 48,2015; A,, 907.W. W. Lucasse, 2. phyaikal. Chem., 1926, 121, 254; A., 796; J. Amer.Chem. SOC., 1926, 48, 626; A., 474.G. Scatchard, ibid., p. 2026; A., 911.W. P. Baxter, ibid., p. 616; A., 474.Ibid., p.2263; A,, 1102. ' E. Schreiner and 0. R. Frivold, Z. physikal. Chem., 1926, 124, 1 ; A,,* Ann. Report, 1925, 22, 34, equation (6).J. Amer. Chem. SOC., 1926, 47, 2098; A., 1925, ii, 971.Rapid progress continues in this field.Thus T. J. Webb1208.io .Tbid., 1926, 48, 326; A,, 35422 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.seriously contradictory to their general theory has developed fromthe numerous results on chloride solutions considered,’’ It isfound that in solutions of constant total ionic strength logfH,,is proportional to its concentration up to 3M. Values of 6 for thesalts are obtained from the Huckel expression, and making thearbitrary assumption that BE. = Sa,, relative values are obtainedfor the ions. In the case of lithium and hydrogen chlorides, thesevalues are so great as to lead to negative values of the dielectricconstant in solutions above 4M.It is suggested that the linearvariation of log f with concentration (when interionic electricaleffects according to the simpler theory have already been takeninto account) has a deeper significance than Hiickel’s theory implies.G. Akerlof has made a similar study of sulphate solutions.11 Thevalue of 6 for the sulphate ion is negative, ie., it is more polarisablethan water and increases the dielectric constant of the medium.All the available data of single and mixed salt solutions are collectedin a paper by H. S. Harned and G. Akerl6f.l2 Good agreementwith the Huckel expression is exhibited in solutions of singleelectrolytes, but only moderate agreement in mixed electrolytes.kerlof 13 has further put forward the idea that the solubility ofa salt is higher the greater its effect (positive or negative) on thedielectric constant of the medium, Using the values of 6 obtainedabove, he shows that there is a close parallelism between the twoquantities.The linear variation of log f with concentration has also beenconikmed by E.Guntelberg 1* for hydrochloric acid in (HC1, MCI)mixtures of constant total-ion concentration. This is shown tobe a consequence of J. N. Bronsted’s rule l5 of the linear variationof the osmotic coefficient in such solutions, and to apply only tomixtures of salts of the same ion-type. The same author hasdiscussed BrBnsted’s principle of the specific interaction of ions lSand its relation to the Debye-Hiickel theory.According to thisprinciple, the activity coe&cient of an ion is made up of two factors :(1) a coeficient of interaction between the ion and other ionspresent, and (2) a “ salting-out ’’ coefficient depending solely onthe other ions present. I n factor (l), it is supposed that ions areuniformly influenced by ions of their own sign and that specificeffects arise only from the interaction of ions of opposite sign.The physical basis of this principle is found in the Debye-Huckell1 J. Amer. Chem. Soc., 1926, 48, 1160; A,, 688.Physikal. Z . , 1926, 27, 411; A., 796.l3 J . Physical Chem., 1926, 30, 1585.l4 2. phpikal. Chem., 1926,123, 199; A., 1207.l6 J.A m . Chem. Soc,, 1922, 44, 877; A,, 1932, ii, 481; ibid., 1923, 45,2898; A., 1924, ii 94GENERAL AND PHYSICAL CHEMISTRY. 23conception, according to which there is in the immediate vicinityof any one ion, a great preponderance of ions of the opposite signand these only are responsible for the specific effects. The Debye-Huckel theory appears to be superior in that it obtains directlythe interionic electrical effects of all kinds. Bronsted‘s formulationis, however, advantageous in the interpretation of relations incertain types of mixed salt solutions (e.g., solubilities of slightlysoluble salts in solutions of various ion-types).I n the last Report, it was pointed out that there is a differencebetween the Milner and the Debye and Hiickel calculations of theinterionic electrical energy (the former being two-thirds of thelatter).This difference has now been elucidated. E. Q. Adamshas pointed out that the quantity obtained by Debye and Hiickelin their first calculation is the free energy change (AF) due tointerionic electrical forces, in the trawfer of ions from a givensolution t o a very dilute solution in which electrical forces arenegligible. Debye and Huckel directly evaluated, in fact, theelectrical work done in removing an ion from its ion atmosphere.Milner, on the other hand, calculated the electrical work done inseparating the ions of a given solution to an infinite distance fromone another. This is the maximum (electrical) work done in aninfinite dilution ( A ; Adams’s AA).Since the latter is two-thirdsof the former, the discrepancy is explained.Debye and Huckel regarded the quantity obtained by themas the mutual potential energy of the ions in solution (U,) andattempted to determine the corresponding work term by meansof the Gibbs-Helmholtz equation AIT = - J U e / T 2 . dT. Inorder to get a result of the correct form, they were obliged to treatthe dielectric constant as independent of the temperature. SinceU, is itself a free-energy quantity, it is necessary to reverse thisprocess to get the true total-energy change. In this way, E. Q.Adams and N. Bjerrum 17 h d that the heat of dilution of a saltsolution is given by AU = - +A(1 + d log Did log T). N. Bjerrumapproaches the matter on the basis of Debye’s second calculation,in which he obtained the electrical work of charging all the ionsin the solution (reversibly) simultaneously.This corresponds to A ,the electrical work of dilution. Debye calculated the correspond-ing free energies of transfer of ions by obtaining the differential ofA for a small addition of one ion species :SA/Sni = Ai = - ~ ~ u z i 2 / 2 0 .Bjerrum greatly simplified the derivation by showing that thel6 J . Amer. Chent. Soc., 1926, 48, 621; A., 474.l7 2. physikal. Chern., 1926, 119, 146; A,, 47624 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.same result may be obtained by considering the electrical work ofcharging a single ion in the given solution. J. A. V. Butler I* hasshown by an independent argument that the quant.ity so obtainedis in reality a free-energy quantity.There appears to be considerable uncertainty about the valueof d log Did log T above; Adams gives - 1.5, Bjerrum - 1.315.Apart from this, Bjerrum compared recorded heats of dilution ofsalt solutions with this equation.The experimental figures (neces-sarily referring to moderately concentrated solutions) are highlyspecific and show little relation to the calculated value. W. Nernstand W. Orthmann l9 have determined the heats of dilution ofsome salts a t very low concentrations. They find even among saltsof the same ion-type no agreement with the equat,ion; in fact,some give positive and others negative values. The theory ofthe heat eflects corresponding to the free-energy changes is thereforeunsatisfactory.that Milner’s theoryaccounts better than Debye’a for the activity coefficients of hydrogenchloride in methyl alcohol is disputed by G.Scatchard.21 Theformer authors, however, questionz2 his method of dealing withthe data. G. NonhebelB has investigated the activity coefficientsof hydrochloric acid a t extreme dilutions. He finds that theequation log,, f = - 0.39fi best fits the results; the Debye-Hiickel theory gives logl, ,f = - 0*5051/& whilst Milner’s givesapproximately log,, f = - 0.37dC.The problem of the determination of the activity coefficients ofan individual ion-species in a salt solution has received some atten-tion. If the activity coeEcients of one kind of ion (e.g., chlorineion) of a salt were known, it would be possible, by correlating thesalts, to determine them in all cases. D.A. MacInnes 24 attemptedthis method by making the assumption that the two ions of potassiumchloride (which have nearly the same weight and mobility) havethe same activity coefficients a t each concentration. G. N. Lewisand M. Randall adopted the same assumption.26The individual activity coefficients could be measured directlyin a concentration cell ‘( with transport ” if the value of the liquid-junction potential were known, since the E.M.F. of such a cellThe claim of G. Nonhebel and H. Hartley18 Phil. Mag., 1927, [vii], 3, 213.1) Sitzungsber. Preuss. Akad. Wias. Berlin, 1926, 51; A,, 579.20 Ann. Repurt, 1925, 22, 33.2 1 Phil. Mug., 1926, [vii], 2, 577; A., 1006.22 IW., p.586; A., 1006. Is Ibid., p. 1085.24 J . Amer. Chem. Soc., 1919, 41, 1086; A., 1919, ii, 385; ibid., 1921, 48,‘ 5 “ Thermodynamios,” 1923, p. 381.1217; A., 1921, ii, 619QENERAL AND PFIYSICAL CHEMISTRY. 25(e.g., H,(HClcllHClc21H2) is given by RT/F . log al/a, + EL,where EL is the liquid-junction potential. If. S. Harned26 hassubjected the '' thermodynamic method " of computing liquid-junction potentials, first used by D. A. MacInnes and J. A. Beattie,27t o a rigorous analysis and has obtained data for the individual ionactivities in mixed chloride solutions.According t o the theory of electrolytic dissociation as formulatedby Arrhenius, the degree of dissociation of an electrolyte is givenby a = &/Am. In the case of strong electrolytes, a decisive massof evidence indicates that dissociation is complete at all dilutions,and variations in the equivalent conductivity A, must be ascribedto changes in the ionic mobilities with concentration.The dis-sociation of weak electrolytes, formerly calculated by the sameformula, must now be corrected for variations in the ionic mobilities.M. S. Sherrill and A. A. Noyes 28 have considered several cases of'' moderately ionised " acids. The true degree of dissociation isgiven, not by &/A, but by A,/&, where A, is the value of theequivalent conductivity for complete dissociation a t the particularconcentration measured. Values of A, are obtained by the Kohl-rausch rule from the equivalent conductivities of completely ionisedsubstances a t the same concentrations, thus :(&)c HA = HC1 f NEA - NaCI.The ionisation constants obtained from the true degrees of dis-sociation are further corrected for the effect of electrical forces bymultiplying each ionic concentration by its activity coefficient,thus : KHr = (fH.a)(fAp a ) / ( l - a)c. In this way, satisfactoryconstants are obtained for the first atage of ionisation of phosphoricand sulphurous acids, and for the second stage of ionisation ofsulphuric acid, assuming in the last case that the first hydrogen iscompletely ionised. D. A. MacInnes 29 has applied similar methodsto a number of weak acids and obtains excellent constants, exceptin the case of acetic acid, in which the values show a definite trendwith concentration. This may be due to inaccurate data, or, it issuggested, to the effect of variations in the dielectric constant ofthe solution, which are not taken into account.The variation of the ionic concentration of water in salt solutionshas been studied.The true equilibrium constant of the ionisationof water is the activity constantKw = UH. . ~ O H . / ~ H , O = fH* . foHI . mw2/aHa0,where m, is the concentration of hydrogen and hydroxyl ions in26 J . Physical Chem., 1926, 80, 433.27 J . Amer. Chern. SOL, 1920, 42, 1117; A , , 1920, ii, 466.Ibid., 1926, 48, 1861; A,, 1006. *I IM., p. 2068; A., 90686 ANNUAL REPORTS ON THE PROORISS OF CHEMISTRY.the solution. An increase of the dissociation of water and otherweak electrolytes on the addition of salts was predicted by J.N.Br8nated.30 Since the activity coefficients of ions initially decreasewith increasing total-ion concentration, the concentrations rn,must increase in order to maintain the equilibrium constant. E.Schreiner31 made some exact calculations of the effect on thebasis of equations representing the effect of salt concentration onactivity coefficients. The older electromotive methods of deter-mining the ionic product of water involved cells with liquid junctions.A new method of determining relative values of the “activitycoefficient product,” fH. . foBt/aRIO, from a combination of datafrom cells without liquid junctions, has been developed.32 Whenthis quantity is known, the ionic concentrations can be determined,suce m, = mB.= may. = u, =. . on. axso). e dissociationof water in solutions of potassium and sodium chlorides,32bromides,33 and sulphates 34 and of lithium chloride 35 has beendetermined in this way. The curves for the alkali-halide solutionsare given m Fig. 1. The dissociation rises t o a maximum a t aboutao J . Amev. Chem. SOC., 1920, 42, 781; J., 1921, 119, 574.31 2. anorg. Chem., 1924, 135, 3 5 7 ; A., 1924, ii, 524.aa H. S. Harned and G. M. James, J. Physical Chem., 1926, 30, 1060; A.,s4 G. Akerlof, Zoc. cit., Ref. (11).36 H. S. Harned and F. E. Swindells, J. Amer. Chem. Sot., 1926, 48;126;l/K-l(f- -~-.~ --- ThH. S. Harned, J . Amer. Chem. SOC., 1925, 47, 930; A , , 1925, ii, 538.907.A,, 246GENERAL AND PHYSICAL CHEMISTRY.270 4 N . I n the sulphate solutions, the maximum value is greaterand the curve flatter.J. Colvin 36 has determined the ion-activity product of water inaqueous glycerol solutions, up to 40% glycerol, by means of electro-motive measurements involving liquid junctions. He h d s thatthe dissociation constant of water remains practically unchangedover the whole range.Ion Hydration in Aqueous Xolution.A number of determinations of the degree of hydration of ionsin aqueous solutions, by means of distribution experiments, haveappeared. The principle of the method, first employed by J. C.Philip,37 is that if the ions are combined with water, the amountof " free water " available for dissolving another substance isreduced.The distribution of a suitable substance between a non-aqueous solvent and the salt solution is studied. Assuming thatthe true distribution coefficient between the solvent and the " freewater " is the same as in pure water, the amount of " free water )'can be determined, and hence the amount combined with the ions.J. N. Sugden38 has made an extensive series of measurements ofthe distribution of acetic acid between amyl alcohol and salt solu-tions, and has deduced the corresponding hydration figures. Exceptin the case of sulphates, the hydration values so obtained arepractically independent of the concentration and, further, areadditive for the ions of salts. Nitrates and chlorates were foundto have negative hydration values, i.e., they increase the apparentamount of water.Relations between the hydration figures andthe viscosity and also the molecular conductivity a t infinite dilutionwere found. For these reference must be made to the paper.Similar measurements have been made by 8. Glasstone and col-l a b o r a t o r ~ , ~ ~ who have determined the solubilities of ethyl acetatein salt and other solutions, and by H. A. Tayl~r,~O who determinedthe partition ratio of hydrogen chloride between benzene and saltsolutions. The latter concluded that there is no appreciabledifference between " free " and combined water, the aqueoussolutions behaving like pure water.It should be observed that the validity of this method dependsa s J., 1925, 127, 2788; A., 246.3 7 Trans. Faraday SOC., 1907, 3, 140; A., 1907, ii, 935; J ., 1907, 91, 711.a s J . , 1926, 174; A., 244.88 S Glasstone and A. Pound, ibid., 1925, 12'7, 2660; A,, 1926, 18; S.Glasstone, D. W. Dimond, and E. C . Jones, ibid., 1926, 2936; S. Glasstone,D. W. Dimond, and E. R. Harris, ibid., p. 2939.Compme J. W.Corran and W. C. McC. Lewis, J . Amw. Chem. SOC., 1922, 44, 1673; A., 1922,ii, 691.J . Physical Chem., 1926, 29, 995; A , . 1925, ii, 85828 ANNUAL REPORTS ON TEE PROGRESS OX CEEMIBTRY.entirely on the truth of the assumption that the solubility in the'' free " water of a salt solution is the same as in pure water. Themeasurements give primarily the relative activity coefficiente ofthe solute employed in various salt solutions, and the relationsfound are not necessarily to be interpreted aa the result of hydration,The problem is identical with that of the " salting-out " effect ofelectrolytes on non-electrolytes, which has recently received muchattention.In many cases, in dilute solutions a t any rate, the effect of anelectrolyte on the solubility of a non-electrolyte is given by V.Rothmund's equation,41 log so/s = kc, where so is the solubilityin water, and s that in a salt solution of concentration c.J. 8.Carter 42 has found that the solubility of iodine in salt solutionscan in most cases be represented by this equation. K. Linder-strom-Lang 43 has made an extensive series of determinations ofk for hydroquinone, quinone, boric acid, and succinic acid. Ageneral explanation of the effect has not been found. A.McKeowniound,44 using P. C. L. Thorne's that there was a correlationbetween the effect of sodium chloride on the solubility of ether inaqueous solutions and its effect on the heat of solution, a relationwhich has a statistical basis. Linderstrom-Lang finds that thisis not general.According to P. Debye and J. McAulay4s the effect is due tothe influence of the electric field of ions on other components of asolution, which causes the more polarisable molecules to amassthemselves round the ion, and the less polarisable molecules to bedisplaced from the vicinity of ions. McAulay4? has consideredthe efiect of non-electrolytes on the solubilities of salts from thesame point of view. He deduces a relation between the dielectricconstant of the solvent and solubility, which accounts fairly wellfor the solubilities of aalts in alcohol-water mixtures.He furtheroutlines a theory suggested by Debye, of which greater detail ispromised later, in which the distribution of water and alcoholmolecules is given as a function of the distance from an ion. Thecurves show that the proportion of molecules of water (the morepolarisable constituent) to alcohol increases rapidly a t 1-2 A.V.from the ion.A new approach from which, it appears, conclusive evidence41 2. physikal. Chem., 1900, 33, 401; d., 1900, ii, 467; ibid., 1909, 69,623; A . , 1909, ii, 980; also Setschenov, ibid., 1889, 4, 117; A . , 1889, 1044.J . , 1925,137, 2861; A,, 236.J . Amcr. Chem. Sococ., 1922, 44, 1203; A ., 1922, ii, 552.43 Compt. rend. Trav. Lab. CarBberg, 1924, 16, 1 ; A., 1925, ii, 30.45 J . , 1921, 119, 262. '' J . Physical Chem., 1926, 30, 1202; A., 1089.4 8 d n n . Report, 1926, 22, 35QENERAL AND PHYSICAL CHEMISTRY. 29as to the nature of the hydration of ions may be obtained, has beenopened up by the study of the energy changes in the solution ofgaseous ions. These may be determined from certain atomisticdata.40 W. M. Latimer 49 has made some new calculations of theenergy of solution of gaseous ions in water, making use of his ionicentropies, and finds a remarkable agreement between his valuesand those calculated by the expression of M. Born,50 AE = (e2/2r)(l -l/B), wherer is the radius of an ion.of charge e , and D is the dielectricconstant of the solvent, using the ionic radii calculated by W.H.and W. L. Bragg from crystal measurements. This equation is asimple electrostatic expression for the energy change in bringinga charged sphere into a medium of dielectric constant D. Latimer’srelation, already described,51 that the entropies of solution ofgaseous ions of one sign vary linearly with the game radii, againshows that the energy effects on the solution of gaseous ions aredetermined by their size and charge. In very dilute solutions, thereis no evidence of specific ion-water combinations, though in con-centrated solution specific effects depending on the nature of theion may come in.T. J. Webb has attempted a direct calculation of the free energiesof solution of gaseous This quantity is regarded as beingmade up of two parts : (1) the difference between the energyrequired to charge the ion in the solution and in a vacuum ; and(2) the work done in compressing the solvent owing to the effectof an electric field on the solvent “ dipoles.” The free energy ofhydration is obtained as a function of the radius of the ‘‘ cavity )’containing the ion in the solution.This radius is obtained byuse of the partial volumes of salts in solution. The apparentvolume of a salt in solution is equal to the volumes of the ion cavities,less the contraction caused in the solution (electrostriction). Anexpression is deduced for the last quantity and by a combinationof the equations it is possible to determine the radii of the ioncavities and the free energies of hydration.The values are checkedby determining some corresponding lattice-energies of solid saltsand electron affinities of halogens. It may be also observed thatK. Jabtczyhki determined limiting volumes of salts in solutionand found values in agreement with the crystal measurements ofBragg.Compare A. Gyemant, 2. Physik, 1924, 30,540.4 6 Ann. Report, 1920, 17, 3.49 J . Amer. Chm. Soc., 1926, 48, 1234; A., 684.so 2. Physik, 1920, 1, 46.I2 PTOC. Not. A d . Sci., 1926, 12, 624; A., 1008; J. A m r . Chem. Soc.,6B Rcoz. Chem., 1923, 3, 362; A.. 1926, ii, 33.61 This Report, p. 17.1926, 48, 2689 j A.. 120890 ANNUAL REPORTS ON THE PROGRESS OF CHB3IISTRP.Velocity of Reaction in Solutions.As indicated in previous Reports,l research in this field, includingthe study of ion catalysis and salt action, has been much concernedwith the significance of thermodynamic activity as a factor deter-mining reaction velocity.Although this question is still open,there appears to be a fairly general conviction that activity is animportant factor. The bearing of the modern theory of electrolytesis beginning to be explored.J. N. Bronsted2 has attempted a general formulation of thefactors governing the rate of ionic reactions in dilute solutions,especially the kinetic salt effect, which is, broadly speaking, muchgreater in reactions between ions than between neutral moleculesor neutral molecules and ions. Thermodynamical considerations,supplemented by the hypothesis that the rate of a reaction A + B =C + D i~ determined by the rate of formation of an unstableintermediate complex A,B (“ critical complex ”), lead to an expres-sion for the velocity, v = k .C A C B , f&fB/fn,B (f is the activitycoefficient), provided that a change of the medium (as, e.g., inchange of ion concentration) involves only activity, not concen-tration, change of the substrate. The charge of A,B is the algebraicsum of that of A and B. Taking the activity coefficients of ionsto be determined only by their charges and the total ion con-centration, and assuming A,B to behave as an ordinary ion, thesign and approximate magnitude of the activity factor F = fzAfa.f(8A+cg) can be evaluated from activity data or from the approxim-ate relation 3 log f = - z2di, where x is the charge of the ion andthe ionic strength, whence v = kCACBe2zAzbdi approximately.For a reaction between a neutral molecule and an ion, F evidentlyrepresents the salt effect on the activity of the former, which, indilute solution, is relatively small and approximately linear.Forreactions between ions, considerable (exponential) salt effects areindicated-positive if the reacting ions have the same, negative ifdifferent signs. Experimental data agree with the theory, butnot always quantitatively.4 The influence of ions increases rapidlywith their valency. In accordance with Bronsted’s ii principle ofthe specific interaction of ions,” the activity coefficient of a1 Ann. Report, 1922, 19, 18; 1924, 21, 34; H.S. Taylor, “PhysicalChemistry,” p. 779.a 2. physikal. Chem., 1922, 102, 169; A , , 1922, ii, 699; ibid., 1925, 115,337; A., 1925, ii, 681.J. N. Bronsted and V. K. La Mer, J . Amer. Chem. Soc., 1924, 46, 555;A,, 1924, ii, 306.A large number of examples are given by J. N. Bronsted, lac. c i t . , ref. (2).6 See this Report, p. 22GENERAL AND PWSICAL CHEMISTRY. 31reactant ion is chiefly influenced by ions of the opposite sign,especially if multivalent.Although recognising its practical value, N. Bjerrum6 andJ. A. Chriatiansen 7 criticise the theoretical basis of Bronsted’sformula, which, however, the former deduces by assuming a differentmechanism of reaction, and also from the kinetic theory. Christian-sen obtains an expression in formal agreement with Bronsted’sby applying the kinetic equation for a gas reaction to solutions,8account being taken of the increased “ inactivation factor,” andespecially of the effect of interionic forces in modifying collisionfrequency and concentration near an ion.The nature and difficultiesof the problem are further exemplified in relation to a study of thereaction between hydrogen peroxide and iodine in which thesalt effect-slightly positive for the salt type Kc1, slightly negativefor the type K,SO,, positive and greater for the type BaCl,-isattributed to changes in the proportion of hydrogen peroxide towater molecules around an iodine ion following the influence onits electric field of the surrounding cations.Factors such as therelative volumes, polarisability, and dipole properties of thesemolecules may be 0perati~e.l~has given a very general kinetic interpretationof activity by which he claims to justify the expression of reactionrates in terms of activities when rates are defined as “ moles trans-formed in 1 mole of all components.” With this modification, heis in agreement with the Bronsted expression.Brief reference may be made to recent studies of reactions betweenions :(1) lorn of the Sffime sign (Strong positive salt effect).-(@) Ter-molecular reduction of ferric chloride by stannous chloride : l2bivalent have twice the effect of univalent cations, and the reactionis bimolecular a t high salt concentration. (6) Bimolecular reactionbetween the cations of mercuric nitrate and chloropentammino-cobaltic nitrate : 13 anions are much more effective than cations.G .Scatchard2. physikal. Chem., 1924, 108, 82; A , , 1924, ii, 240; ibid., 1925, 118,251; A., 131. ’ Ibid., 1924, 113, 35; A., 1925, ii, 47.Previously considered by M. Trautz, 2. anorg. Chem., 1919,106, 149; A.,J. A. Christiansen, 2. physikal. Chem., 1925, 117, 433; A., 1926, 33.See in this connexion Ann. Beport, 1925, 22, 35; this Report. p. 28.J. Amel. Chem. SOC., 1923, 45, 1681; A., 1923, 5, 626,U’. F. Timofbev, G. E. Muohin, and W, G. Gurevitsch, 2. physikal. Chem.,l3 J. N. Bronsted and C. E. Teeter, J . Phyaicul Chem., 1924, 28, 670; d.,1919, ii, 327.1935, 115, 161 ; A., 1926, ii, 686.1924, ii, 74532 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.( G ) Oxidation of iodide by ferricyanide.14 (d) Saponification ofesters of dibasic acids : l5 the first stage shows a small (linear) salteffect, the second a large positive (exponential) effect-the cationiccharge is the chief factor and the activity factor P calculated fromthe ionic strength accounts for the observed rates.( e ) The photo-decomposition of uranyl formate in formic acid : 16 the magnitudesof salt effects are in good accord with Brbnsted’s theory.(2) Ions of Opposite sign (Strong negative salt effect).-@) Re-action between hydrogen, iodine, and iodate ions; here the salteffect is quantitatively accounted for by the factor F = 1 0 - 2 . 2 0 J 2 ~over a considerable range of ion concentration.The factor 2.20is greater than the value calculated from the Debye theory. Thereaction in acetate buffers is accounted for in a similar way.17( b ) Reduction of ferric salts by thiosulphate.l*When the reacting system contains a weak electrolyte the additionof neutral salt may displace its equilibrium,19 and the consequentchange of concentration gives rise to a “secondary salt effect,”the “primary effect” being due to activity change on1y.m Theformer depends on salt effects on the activity factor in the expres-sion for the dissociation constant of the weak electrolyte :K = (~Ac*l[B,I/~(AB),l)(f,f,/f,) ;such activity effects can be calculated approximately on t,he basisof the interionic-attraction theory. The salt action is positive ornegative according to the type of weak electrolyte.Writing theequilibrium as A + B =e C + catalyst ion, the general rule is :As the sum of the squares of the ionic charges of the reactants isgreater or less than this sum for the resultants, so the secondarysalt effect is negative or positive. This principle has been experi-mentally verified.20 The catalytic decomposition of nitrosotri-acetonamine by hydroxyl ions shows, e.g., a positive effect in thepresence of piperidine, negative in the presence of phosphate , andvery little effect, as expected, in the presence of sodium amino-acetate 2 1 (NH,CH,GOO’ + H,O + NH,*CH,*CO,H + OH’).14 C. Wagner, 2. physikal. Chem., 1924, 113, 201; A., 1925, ii, 49.1 5 J. N. Bronsted and A. Delbanco, 2. anorg.Chenb., 1925, 144, 248; A , ,1 6 G. Berger, Rec. trav. chim., 1925, 44, 47; A., 1925, ii, 313.1 7 E. Abel and F. Stadler, 2. phpikal. Chem., 1926, 122, 49; A,, 1009.18 J. Hollute and A. Martini, 2. anorg. Chem., 1924, 140, 206; 141, 23;19 J. N. Bronsted, J . , 1921, 119, 674.20 Ref. (13); J. N. Bronsted and C. V. King, J . Amer. Chem. Soc., 1925, 47,2 523; A., 1925, ii, 1171; J. N. Bronsted and K. Pedersen, 2. physikal. Chem.,1924, 108, 186; A . , 1924, ii, 331.1925, ii, 684.1925, 144, 321; A , , 1925, ii, 305, 215, 702.11 ill. alpatrick, J . Amer. Cheat. Soc., 1926, 48, 2091; A., 919GENERAL AND PHYSICAL CHEMISTRY. 33(3) Ions and Neutral Molecules.-It is in the large class of reactionsbetween neutral molecules and ions, including ion catalysis, thatthe question of the significance of activity has received the mostattention.The unirnolecular decomposition of hydrogen peroxide 22in bromine-bromide solutions (virtually, catalysis by hydrogenbromide of constant concentration) is given by the equat'ion- d[H,O,l/dt = kJH,O,I[H'I"r'] ,fkmfor ionic strengths not exceeding 1.0 ; the * ' concentration !' velocitycoefficient k, (in contrast with the " act,ivity ? ' velocity coefficient,k,) shows a marked drift,. Similar relations apply to the chlorine-chloride reaction.22 J. A. Christiansen % has criticised this formul-ation in the particular case of the above react'ion. Thc conversionof 3-chloroacetanilidc into p-chloroacet,anilide 24 is exactly pro-portional t o the activit'y product of t'he hydrogen chloride catalyst.The rate of addition of hydrogen chloride to quinone in ethyl-alcoholic solution is stated 25 to be governed by the activity productof the hydrogen and chlorine ions. Proportionality between rateand activity is also supported in studies of the reaction betweenformic acid and bromine or iodine.268.W. Pennycuick 27 has attempted to settle the disputed questionwhether the inversion of sucrose follows strictly the unimolecularlaw. His very accurate measurements 28 show a small increaseof k during reaction. Postulating that water molecules are activ-ated by association with hydrogen ions, w = k [sugar mols. per mol.H,0][H',nH20], the last term being assumed proportional to thehydrogen-ion activity which does apparently increase slightlyduring inversion.Previous investigators 29 found no evidence ofthe latter, but T. W. J. Taylor and It. F. Bomford30 observed a7% increase in the presence of salt. G. Scatchard's31 analysis2 z W. C. Bray and/or R. S. Livingston, ibi&., 1913, 45, 1251; A , , 1923,ii, 473; ibid., p. 2048; A . , 1023, ii, 747; ibid., 1915, 47, 2069; A . , 1925,ii, 981; ibid., 1926, 48, 46, 53, 406; A., 246, 251, 364.23 2. physikal. Chem., 1925, 117, 448; A., 1926, 33.24 H. 8. Harned and H. Seltz, J. Amcr. Chem. rSoc.. 1922, 44, 1476; A . ,1922, ii, 631; A. C. D. Rivett, Z. phpikal. Chem., 1913, 82, 201; 85, 113;A . , 1913, ii, 205, 1041; G. Akerkf, Medd. I<. Votenskapsakad. Nobel-Znsl.,1922, 6 , No. 2.z 5 L. Ebert, 2.Etekhmltem., 1966, 31, 113, 209; A., 1995, ii, 408, 586.28 D. L. Hammick, W. K. Hutchison, and F. R. Snell, J., 1925,127, 2715;D. L. Haminick and M. Zvegintzov, J., 1926, 1105; A,, 691.2 7 J . Amer. Chem. Soc., 1926, 48, 6 ; A., 949.2 8 Ann. Repolt, 1924, 21, 14.l8 H. A. Feles and J. C. Morrell, J. dmer. Chem. Soc., 1912, 44, 2071; A . ,Jo J., 1924, 125, 2016; A., 1924, i, 1256.81 J. Amer. Chem. SOC., 1926, 48, 2259; A,, 1107.A,, 1926, 32.1922, ii, 832; C. M. Jones and W. C. McC. Levis, J . , 1920, 117, 1120.REP.-VOL. XXIII. 34 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.of Pennycuick’s data indicates, however, constancy of rate towithin a few parts per 1000, the observed increase being attributedto a systematic error. Scatchard32 has come to the conclusionthat the difficulties attending the accurate electrometric measure-ment of hydrogen-ion activity in sucrose solutions are such as torender inconclusive the previous attempts of himself and others 34to determine the mechanism of the inversion process by fitting therates of reaction with formuls containing this activity.It mayhere be noted that the same author, discussing the correlationof reaction rate and viscosity, indicates the great experimentaldifficulties involved, and shows that the kinetic theory requiresno viscosity effect. A viscosity correction has been employed byW. C. McC. Lewis and others.35The acid catalysis of lactone formation, which shows all thecharacteristic features of hydrolytic reactions, has been studiedin water, ether, and water-ether mixtures by H.S. Taylor andH. W. Close.as New evidence is found for believing that the rateis determined by the hydrogen-ion activity only, the activity,viscosity, and hydration factors employed by previous investig-ators 37 being regarded as very uncertain.According to M. Kilpatrick 38 the rate of decomposition of nitroso-triacetonamine by alkali is decreased in the presence of glycerolto about the same relative extent as the decrease of the hydroxyl-ion activity in J. Colvin’s30 measurements of hydrogen- andhydroxyl-ion activities in glycerol-water mixtures ; the increasedactivity of the hydrogen-ion in such mixtures would explain theaccelerating effect of glycerol in hydrogen-ion catalysis.The theories of salt action mentioned above refer in the firstplace to dilute solutions.G. Grube and G. Schmidm find thatthe salt effect on the hydrolysis of cyanamide by dilute nitric acidin solutions of nitrates (linear a t low salt concentrations) is ex-ponential for concentrations from 1N to saturation ; k = k,,ercwhere k and k, are velocity coefficients for solutions of the same32 J. Amer. Chem. Sac., 1926, 48, 2026; A., 911.a3 Idem, ibid., 1923, 45, 1581; A., 1923, ii, 626; ibid., 1921, 43, 2387;A., 1922, i, 230.* I T. Moran and W. C. McC. Lewis, J., 1922, 121, 1613; C. M. Jones andW. C. McC. Lewis, ref. (29).35 Ref. (29), and Ann. Report, 1942, 19, 19; W. H. Garrett and W. C. MoC.Lewis, J. Amer. Chen. Soc., 1923, 45, 1091; A., 1923, ii, 47fi; J.Colvin,Trans. Faradau Sac., 1926, 22, 241; A., 1109.a s J. Physical Chem., 1025, 29, 1085; A., 1926, ii, 1070.87 Uarrett and Lewis, ref. (35).as Ref. (21).40 2. physikul. Chem., 1926, 118, 19; A,, 474; also 0. Schmid and R.This Report,, p. 27, ref. (36).Olsen, ibid., 124, 97GENERAL AND PHYSICAL CHEMIBTRY. 35acidity containing respectively c and 0 equivalents of salt, and Tis the " specific salt effect." This relation is valid for other reactions,whilst a similar relation, a = aoe''c, applies to the salt effect onthe thermodynamic activities 41 except a t low concentrations( < 1 W ) where, owing to interionic forces, a lowering of ion activityoccurs. This law is considered incompatible with the "dualtheory )) of catalysis.The fact that T and r' are independent oftemperature 42 does not agree with Bjerrum's theory that catalysisis determined by the equilibrium H',nH,O =$ H' + nH,O. WhilstGrube and Schmid's relation is in agreement with Huckel's activityexpression,43 Schmid and Olsen 42 prefer to account for deviationsfrom the exponential law (activities) a t low concentrations, not bythe interionic-attraction theory, but on the basis of G. Tammann'stheory of internal pressure.44 From the measured external-pressureeffect on the hydrogen-electrode potential (in the absence of freehydrogen g a ~ ) , ~ 5 and assuming internal-pressure changes due t othe salt to exert the same effect on the electrode as external pressure,the true salt effect (total effect less pressure effect) on the hydrogen-ion activity is in agreement with the exponential equation a t lowas well as a t high salt concentrations.G.&erlof,46 in a very recent paper, gives strong evidence infavour of the general rule that the velocity always follows theactivity of the catalyst ion for hydroxyl- as well as hydrogen-ioncatalysis in salt solutions. I n the hydroxyl-ion catalysis of thedecomposition of diacetone alcohol the curves expressing thechange, with salt concentration, of the reaction velocity and ofthe hydroxyl-ion activity are, for a series of chlorides, in the sameorder, just as in the acid catalysis of the N-chloroacetanilide trans-f~rmation.~' The salt effect on the hydroxyl-ion activity, thermo-dynamic and catalytic, is the reverse of that on the hydrogen-ionactivity, and an attempt is made to relate reaction velocities inacid and alkaline salt solutions to the water equilibri~m.4~ b e r -lof 49 has found the relation klk, = (cb/a,JDIC''* for the I\.'-chloro-acetanilide transformation in acid-salt solutions (D is a constant ;C concentration of salt; and a , a,, the hydrogen-ion activities41 For a review of the literature see ref.(40).45 G. Schmid and R. Olsen, ref. (40), where further references and a dis-43 Ann. Report, 1923, 22, 34, equation (6); this Report, p. 21.44 G . Tammann, " Uber die Beziehungen zwischen den inneren Krilften4 5 G. Tammann and H. Diekmann, 2. anorg. Chem., 1926, 150, 129; A.,46 J . drner. Chem. Soc., 1926, 48, 304C.4 7 Refs.(24) and (46).48 Medd. K . Vetenskapsakad. NobeLIwt., 1926, 6, No. 2, 1 ; A., 1926, 126.See also this Report, p. 21.cussion of Bjerrum's theory are given.und Eigenschaften der Losungen " (Hamburg and Leipzig, 1907).360.4 B This Report, p. 2636 ANNUAL REPORTS ON THE PROQRESS OF CITEMIISTRY.with and without salt, respectively). His earlier relation 50 E = cvafor ester hydrolysis has been questioned.51Following A. L a p w ~ r t h , ~ ~ N. ’Bjerrum 53 and others, F. 0. Riceand associates advocate a theory of unhydrated-ion catalysis(‘( protions,” present in small concentration), which they extendto a general theory 55 that the velocity is determined by the con-centration of (‘ residual )’ molecules in equilibrium with othercomponents of the system.The theory is largely based on acomparison of the temperature coefficients of similar reactions.The affinity for water of the hydrogen ion being greater than thatof the hydroxyl ion, neutral solutions are “ catalytically alkaline,”and the catalytic minimum point for reactions catalysed by bothions should be at practically the same acidity for all such reactions.This minimum is in fact often found 56 a t about pE 5. Incon-sistencies with the theory are indicated in that the minimum(pH 4.8) for the autocatalytic reaction between iodine and acetonein aqueous solution is not affected by temperature and neutralsalts,ss and that the p H values for benzamide and acetamidehydrolysis are higher than predicted, viz., 598 and 6.2, respe~tively.5~Further support has been given to the theory 58 that substancessubject to hydrolytic reaction in the presence of both acid andalkali (e.g., esters) are weak ampholytes, the rate being determinedby the concentration of the positive or negative ester ion, whichis increased respectively by the acid or alkaline catalyst, and iscalculable from the two equilibrium constants K , and Kb.Assum-ing equal reactivity of these ions, the relation between rate and p ,5 O Ann. Report, 1922, 19, 19.61 Gmbe and Schmid, ref. (40); also ref. (46).6* J., 1908,93, 2187; also J. Kendnll and P. M. Gross, J . A ~ E T . Chem. ~Soc.,1921, 45, 1416; A., 1922, ii, 32.6a 2. anorg. Chem., 1920, 109, 275; also E. Sohreiner, ibid., 1922, 121, 321 ;A., 1922, ii, 468; ibid., 1924, 135, 333; A ., 1924, ii, 524.54 F. 0. Rice and M. Kilpatrick, J . Amer. Chem. SOC., 1923, 45, 1401; A.,1923, ii, 548; F. 0. Rice and W. Lemkin, ibid., p. 1896; A., 1923, ii, 678;F. 0. Rice, ibid., p. 2808; A . , 1924, ii, 98; F. 0. Rice, C. F. Fryling, andW. A. Wesolowski, ibid., 1924, 46, 2405; A , , 1925, ii, 48; F. 0. Rice andC. F. Fryling, ibid., 1925, 47, 379; A . , 1925, ii, 556.6s The general character of this theory has been disputed; see C. N. Hinshel-wood, Chem. Revieuw, 1926, 3, 230 ; idem, ‘‘ The Kinetics of Chemical Changein Gaseous Systems,” 1926, p. 155; R. C. Tolman, J . Amer. Chem. SOC., 1925,47, 1626.61 For collected data see M. Bergstein and M. Kilpatrick, J . PhysicalChem., 1926, 30, 1616.I. Bolin, 2.anorg. Chem., 1925, 143, 201; A , , 1925, ii, 411.6 8 H. von Euler and 0. Svanberg, b. physiot. Chem., 1921, 115, 139; A.,1922, i, 219; H. von Euler and E. Rudberg, 2. anorg. Chem., 1923,127, 244;A., 1923, ii, 840; 2. Physik, 1923,16, 64; A , , 1923, ii, 647GENERAL AND PHY SIOAL CHEMISTRY. 37is given by a symmetrical U-curve with a minimum a t the isoelectriopoint :v = ko + k,,t.[E'l + kdE'1 = Lo + k.,,t.Ka[H']/k,~ + Em.Ka/[HIwhere E' and E' are the ester ions and A and B are constants.Recent work59 is in good agreement with the theory. Contraryto earlier observations,60 the two limbs of the curve are of equalslope. Ethyl benzenesulphonate (non-ampholyte) shows quitedifferent behaviour. Some doubt attaches to the significance ofko ; possibly it gives the activity of the ' * zwitterions." Salts havevery little effect on the catalytic-minimum pH.The inversion ofsucrose has been discussed from the same point of view.61Studies on the catalytic minimum of the iodine-acetone reaction(referred to above), in buffer solutions, have been made by H. M.Dawson and associates.62 Not only is support found for the" dual " theory of catalykis, which has found little favour in recentyears, but it is extended to the anion, the observed rates beinggiven by the equation v = kH.[H'] + k,,[HA] + k,.[A'] with theaddition of the term koH,[OH'] a t low hydrogen-ion concentration.Assuming complete dissociation of the salt, and also the validityof the concentration " expression for the dissociation constant,K,, of the weak acid, a symmetrical U-curve is theoretically pre-dicted when v is plotted against pa, in excellent agreement withexperimental data.Catalytic activity is proportional to volumeconcentration of the catalyst calculated from K,, and no oonnexionis found between velocity and thermodynamic activity.Mutarotation.Recent research on the mechanism of mutarotation of the sugarsis of interest in relation to the claim of J. W. Baker, C. K. Ingold,and J. F. Thorpe63 to have obtained conclusive proof that thisphenomenon is purely a tautomeric change involving (contrary tothe previously accepted view) no intervention of water. Accord-ing to T. M. Lowry and E. M. Richards,64 the experimental results= k o + B I H ] + A / [ H ] .. . . * (4)58 K. G . Karlsson, Z. anorg. Chem., 1925, 145, 1; A,, 1925, ii, 877.E o IbLd., 1931, 119, 69; A., 1922, ii, 40; Bnn. Repart, 1922, 19, 19.61 H. von Euler and A. Olander, 2. anorg. Chem., 1926,156, 143; A., 1108.6 3 H. 31. Dawsonand J. S. Carter, J . , 1926, 2382; A., 1108; H. M. Dawsonand N. C. Dean, abid., p. 2872 ; H. &I. Dawson and C. R. Hoskins, ibid., p. 3166.83 Ann. Repmt, 1924, 21, 13; J., 1924, 125, 268; A., 1924, i, 262. Theseauthors based their conclusions on a mathematical analysis of the dynamicsof mutarotation, end on the observation that very small amounts of waterhad no effect on the velocity of mutarotation of tetra-acetyl glucose dissolvedin ethyl acetate, and of glucose in methyl alcohol.J., 1925,127, 1386 ; A., 1925, i, 886 ; Bee also T.M. Lomrg, zbid., p. 1371 ;A . , 1925, 1, 886 (a reply to Baker, Ingold, and Thorpe, and a general dis-cusaion of the meohamsm of mutarolabon)38 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,of these authors were largaly invalidated by the presence of unknowncatalytically-active impurities, in the absence of which muta-rotation can generally be suspended in a dry solution. Further, int’he presence of the very small amounts of water used by Baker,Ingold, and Thorpe, the value of dk/d[H,O] should be so small as tobe experimentally indistinguishable from the zero value which theyfound and regarded as incompatible with the ‘‘ hydrate theory.”Lowry 64 has re-examined the whole question, and, on the basisof modern views on valency, has extended his mechanism for acidand alkaline ester-hydrolysis to the analogous mutarotation of thesugars, thus going far towards a reconciliation of previously con-flicting views.Both phenomena are regarded as ionic in character.The former proceeds through the formation of bi-polar molecules(ewitterions) by addition of H+ and OH-, one of these being derivedfrom the acid or alkali, the other from water, thus :P + F1OH H OHCH,-CO.O.CH, =+= CH,*$:-?*CH, =+= CH,*C + HOCH,.The latter is attributed to the formation, by a similar ionic mechan-ism, of an intermediate aldehyde form of the sugar; but as this isnot necessarily hydrated, it may be produced by isomeric changewithout addition of water. Since the hydroxyl ion does not thenplay any essential part in this change, the proton transfer (‘i proto-tropic change ”) can proceed in any medium which is capable of(1) accepting a proton from one part (OH group) of the sugarmolecule, and (2) giving a proton to another part (C-0-C group).Regarding an acid as a ‘‘ proton donator ” and a base as a “ protonacceptor,” an effective solvent for mutarotation should thus beamphoteric in character, e.g., water; acidic and basic solventsshould be effective only in the presence of water, or of each otherif water is absent.This view has received striking experimentalsupport.s5 In general, pure, dry, neutral solvents are ineffective,whilst pyridine and cresol, ineffective when dry, become active inthe presence of water, and develop great catalytic activity whenmixed in the dry state.The “ hydrocatalysis )’ theory has thusbeen not only maintained but extended.H. von Euler’s theory of ester hydrolysis, referred to above, hasbeen applied to the mutarotation of glucose.66 The U-shapedk-pE curve is nearly symmetrical, with a shallow minimum at theT. M. Lowry and I. J. Faullmer, J., 1925, 127, 2883; A., 1926, 148.6 5 Refs. (58), (59), (61); H. von Euler, A. Olander, and E. Rudberg, 2.anorg. Chem., 1925,146, 45; A , , 1925, ii, 876; H. von Euler end A. Olander,ibid., 1926, 152, 113; A., 580GENERAL AND PHYSICAL CHEMISTRY. 39isoelectric point pH 5 ; k changes little between pH 2 and pE 8.The two dissociation constants of the amphoteric sugar are of theorder K , = 10-13, Kb = 10-ls, whence can be calculated the con-centration of sugar anions and cations t o which the rate is pro-portional ; between p , 2 and p E 8 the determining factor is regardedas a function of the zwitterions or neutral molecules.Equation (4)reproduces the experimental data.07 The nearly-equal slope ofthe two arms of the curve indicates approximately equal reactivityof the two sugar ions, kcat. and kan. being a t least 1000 times greaterthan k,. R. Kuhn and P. Jacob 68 are in general agreement withvon Euler, but, from a study of salt action, they believe that thevelocity of mutarotation depends on activity rather than on con-centration of the reactants, and they therefore find evidence forthe conclusions of Baker, Ingold, and Thorpe in the fact that thevelocity remains unchanged in solutions varying from 2%--50% ofsugar in spite of a 200/, change in the activity of water.I n thisconnexion, it may be noted that G. G. Jones and T. M. Lowry 69find no relation whatever between the velocity of mutarotation oftetramethyl glucose in water-acetone mixtures and the aqueousvapour pressure of such mixtures ; they conclude that the catalyticeffect of water is proportional neither to its concentration nor toi t 3 activity.Optical Activity.In the last Report on this subject,l prominence was given tocriticisms of T. M. Lowry’s well-known system of classifying rotatorydispersion as “ simple ” or “ complex,” according as it can orcannot be expressed by a one-term Drude equation. The systemwas regarded as lacking justification on practical as well as theor-etical grounds, and a return to the older classification into “ normal ”and “ anomalous ” rotatory dispersion was considered desirable.These conclusions were largely based on H.Hunter’s examinationof the two-term Drude formula = ko/(h2 - hO2) + kJ(X2 - h?),which indicated that a sharp distinction between simple and com-plex rotatory dispersion would be difficult, except when the complexdispersion was also anomalous, and impossible if the componentpartial rotations of the coinplex dispersion were of similar sign?Recent work has, however, proved that the difficulties in the6 7 C. S. Hudson’s empirical formula is thus given a theoretical significance;J . Ante?. Chem.Soc., 1907, 29, 1672; A., 1907, ii, 942.6 8 Z. phipikal. Chem., 1924, 113, 389; A., 1926, ii, 49.J . , 1926, 720; A., 481. Ann. Report, 1924, 21, 3, 61.2 J., 1924. 125, 1198; A., 1924, ii, 645.3 ‘‘ I n practice it will be impossible to detect the departure of the I/= - pcurve froiii linearity when k, and k, are both positive. If the rotation con.stants are of opposite sign, and if b,>b, when ,&,>A, detection will be possibl40 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.practical application of Lowry‘s system are by no means so greatas Hunter suggested. Complex rotatory dispersion was easilydemonstrated in ten halogen derivatives of ~amphor,~ althoughonly one of them showed anomalous dispersion. With one exception(where a more complex equation was required), all these dispersionscould be represented by two-term equations, the terms being.ofsimilar sign in three cases and of opposite sign in the others ; butonly in one case were the conditions fulfilled that the rotationconstants should be opposite in sign and Ic,<k, when h,71,.3Further, the undesirability for practical reasons of abandoningthe classification of rotatory dispersion as simple and complex, infavour of the normal and anomalous grouping, is evident from theconsideration that, in critical cases, the latter depends on knowingwhether a reversal of sign would occur if the dispersion-curve couldbe followed into the infra-red region (usually impracticable a tpresent), whilst the former can be checked by direct observationup to the limit of transparency in the ultra-violet.For example,the rotatory dispersion of P-bromocamphor is complex but normal,5since k,>k, when Ao>hl, but the margin is so narrow that thecalculated curve only just fails to cross the A-axis ( L e . , CL just failsto suffer reversal of sign); any doubt as to the validity of theequation would a t once make the extrapolation into the infra-redregion so uncertain that it would be impossible to decide whetherthe rotatory dispersion were normal or anomalous.6 As a practical,and in the first place empirical, method of Classification, Lowry’ssystem seems to be justified.The question of its theoretical significance as distinct from itspractical utility has been recognised in the attempts to correlateonly in very rare cases.The only condition under which the experimentaldata can be expected to show the effect whieh Lowry and Dickson regard asevidence of ‘‘ complex ” dispersion is when the rotation constants are oppositein aign and k,<k, when Ao>A,.”4 J. 0. Cutter, H. Burgess, and T. M. Lowry, {., 1925, 127, 1260; d.,1925, ii, 743. For other examples see E. M. Richards and T. M. Lowry,ibid., p. 1512; A., 1925, ii, 934.(Ann. Report, 1924, 21, 3.)6 T. M. Lowry and J. 0. Cutter, ibid., pp. 606, 608; A., 1925, ii, 356.T. M. Lowry has introduced the term ‘‘ quasi-anomalous ” t o describecases of ‘‘ complex but normal ” rotatory dispersion (e.g., camphor), in whichalthough Iso and k, are of opposite sign, the resulting dispersion-curve showsno obvious anomalies, merely because the relative magnitudes of k, and k,are not such a@ to give rise to a reversal of sign.See ref. (5), p. 608 ; T. 31.Lowry, J. Chint. physique, 1926, 23, 6 6 5 ; Nature, 1926, 117, 274.T. M. Lowry and E. M. Richards, J., 1924,125, 2511; A., 1925, ii, 265 (areply to Hunter’s criticisms and a discussion of the practical and theoreticaljustification of the use of the Drude formula).* See R. H. Pickard and H. Hunter, ibid., 1923, 125, 436, and Ann. Report,1923, 20, 15 et segUENERAL AND PHYSICAL CHEMISTRY. 41the wave length 7b0 of the dispersion constant in the Drude formula(as determined from rotatory-dispersion measurements only) withthat of the head of the dominant absorption band 1,.Such acomparison has been made in the case of ~ a m p h o r , ~ camphor-q ~ i n o n e , ~ and nine halogeno- and five sulphonic 9 derivatives ofcamphor; h,, always exceeds ha by roughly 100-150 A.V. Thediscrepancies are, a t any rate in part, accounted for by the dis-placement of h, due to superposition of selective and generalabsorption, and these results are regarded as affording some justi-fication for the use of the Drude formula from the themetical stand-point, since, according to the theory h, represents the wave-lengthof the band controlling rotatory dispersion.sA summary and discussion of the types of optical superposition,any of which may cause complex or anomalous rotatory dispersion,has been given by T. M. Lowry and J.0. Cutter.lo Six classesare now distinguished, viz., those of : (a) Two separate media;(6) two mixed, stable, fluid media; (c) two molecular types derivedfrom one optically-active compound, one type being generally thatcomposing the crystal, the other being produced either (i) bypolymerisation, dissociation, or isomeric change of the solute, or(ii) by chemical reaction with the solvent ; ( d ) radicals of oppositeactivity in one molecule; ( e ) induced asymmetry of double bondsin an asymmetric molecule ; (f) possibly two natural frequencies(i) in a single crystal, (ii) in a single molecule. A recent study4of the mono- and di-halogeno-substitution products of camphorstrongly supports the general validity of the principle of opticalsuperposition, the different asymmetrical centres in a moleculecontributing independent partial rotation to the observed total.11E. Darmois,12 reviewing physical theories of optical rotation,concludes that none of them can explain the considerable effectsof solvent, concentration, and temperature, and that physico-chemical theories [e.g., of dynamic isomerism, class ( c ) above]provide a satisfactory mechanism.Support for the isomeridetheory is found by A. Haller and R. Lucas l3 in the approximateCOnStanCy of the ratio ([.]A - [ctIB)/([alA - [.IC) over the range4358-6708 A.U. for various derivatives of camphor in five solvents,including phosphoric acid l4 (A, B, and C refer to different solvents).This rule, a consequence of Biot's law of mixtures, is accurately8 E.M. Richards and T . M. Lowry, J., 1925, 127, 1503; d., 1925, ii, 934.lo Refs. (6) and ( 6 ) .l1 See criticisms by T . 8. Patterson, Nature, 1926, 117, 786, and remarksl* J . Phys. Radzum, 1925, [vi], 8, 232; d., 1926, ii, 1119.13 Compt. rend., 1925, 180, 1803; R. Lucas, ibid., 181, 45; A . , 1925, ii, 742.l4 Idem, ibid., 1926, 182, 1022; A., 662.by T. M. Lowry, ibid., p. 787.B 42 ANNUAL REPORTS ON THE PROGRESS OZF CHEMISTRY.obeyed when B is a mixture of A and C. Again, the dextrorotationof camphor, less in formic acid than in benzene, becomes a slightlsvorotation in concentrated nitric or phosphoric acid, and a stronglaevorotation in concentrated sulphuric acid.15 Camphor is there-fore considered to exist in solution as an equilibrium mixture oftwo forms, a and p, of opposite rotatory power, the two terms ofthe Drude formula for camphor 5 representing the effects of theseisomerides.The approximate agreement of the positive term withthe rotation constant for crystalline camphor suggests the identityof the or-isomeride with crystalline camphor, as in the case of tartaricacidsfs According to L. Longchambon,17 there is no justificationfor regarding the Drude terms as characteristic of such CL and pisomerides, but R. Lucas14 maintains that as a first approxim-ation they may be so regarded. It may here be noted thatLowry and his associates have obtained strong evidence that incamphor the superposed optical effectB are (1) that of the fixedasymmetry of the saturated carbon atoms, -and (2) that of theinduced asymmetry of the ketonic group, since in most camphorderivatives the positive partial rotation is controlled by a dis-persion constant corresponding approximately with the wave-lengthof the ketonic absorption band.6T.M. Lowry and W. R. C. Coode-Adams 1* have measured withthe greatest possible accuracy the rotatory power from infra-redto ultra-violet (25170-2263 d.U.) of a quartz column nearly50 cm. long. The dispersion formula- 0.1905, 9.5639 2.3113h2 - 0,0127493 - h2 - 0*000974 a =which is valid for the whole range, postulates the existence ofbands of selective absorption a t 1130 and 310 d.U., the influenceof infra-red bands being covered by the small constant, - 0.1905.In spite of numerous attempts to find a general physical theoryof optical activity which can be experimentally tested, it cannotbe said that any great success has yet been attained.The incor-poration by Drude of a rotation term in his theory of dispersionnecessarily provided for optical rotation, but no real explanationof the phenomenon was thereby aff orded.12 Further, the theorytook no account of solvent and concentration effects. The latterwere associated with the refractive index of the medium in theLorentz-Livens theory, which, however, did not explain the con-R. Lucas, Compt. rend., 1926,182, 378; A., 337.l0 Ann. Report, 1924, 21, 59.1' Compt. rend., 1926,182, 769; A., 559.la Roy. Soc., Dec., 1926 (in press); Nature, 1926, 118, 861GENERAL AND PHYSICAL CHEMISTRY.43nexion between rotation and molecular asymmetry. The latertheories of M. Born,1Y C. W. Oseen,20 F. Gray,21 and A. Land622were, on the other hand, definitely based on molecular asymmetry;they agree broadly in ascribing rotation to unsymmetrically-disposedelectron resonators coupled together, i.e., reacting by mutualinduction. The relations obtained are complex and do not permitof estimating the order of magnitude of the effect. (Sir) J. J.Thornson's theory,23 although physically and mathematicallysimpler, involves molecular magnitudes at present unknown.A new attack on this problem has recently been made by R. deMallemann,24 who has extended the ordinary dispersion formulsby the introduction of the single notion of molecular asymmetry ;his analysis involves the orientation theory put forward by Lan-gevin in connexion with the Kerr effect.The problem of calculatingoptical rotation appears thus to have been brought appreciablynearer solution. The rotation calculated for a tetrahedral moleculeof the type CHClBrI is of the right general order of magnitude,which is all that can be hoped for a t present. Complete solutioninvolves a fuller knowledge of molecular structure than we yetpossess. Optical rotation, according to this theory, (1) dependson the geometrical form only of the tetrahedron which is deter-mined by the atoms a t the apices (the analysis does not call forknowledge of the forces producing the structure), (2) is proportionalto the product of the refractivities of the four atoms, thus accountingfor the known influence of heavy atoms and of double bonds.Itappears, further, that as regards rotation an asymmetric group ofatoms behaves almost independently of the rest of the molecule.The analysis indicates great sensitiveness of optical rotation t omolecular structure, so that failure to express the experimentalvariations by any simple law is not surprising.Electrification at Surfaces."It has long been realised that the Helmholtz conception of theelectrical double layer a t surfaces as two layers of ions of oppositecharges confronting each other a t a 6xed distance (condenser19 Ann. Physik, 1918, [iv], 55, 1 7 7 ; A , , 1918, ii, 283.22 Ann. Physik, 1918, 56, 225; PhysibaE. Z., 1918, 10, 300.*3 Phil. Mag., 1920, [vi], 40, 713.*' A,nn. Physique, 1924, [XI, 2, 5 ; 1925, [XI, 4, 456; A . , 1926, ii, 1029;Compf. rend., 1923,177, 427; 1925,181, 106, 298, 371; A., 1925, ii, 840, 935,1030. See also ref. (12). * See the Faraday Society's discussion on electrification at surfsoes(Trans, Pa'oraday SOC., 1926, 22, 434). Some of the papers contributed &rereferred-to below.Ibid., 1915, 48, 1. 21 Physical Rev., (Z), 1916, 7, 47244 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.fashion) is inadequate. J. Billiter and G. Gouy suggestedthat ions in the liquid form a diffuse layer. D. L. Chapman3applied the Boltzmann equation to obtain the distribution of ionsin a diffuse layer, but his equations have been shown to be in-adequate.4 0.Stern 5 has therefore postulated a combination ofthe two types-a (‘ condensed ” double layer near the surface ofseparation ; beyond it, in the liquid, a ( ( diffuse ” layer of ions.The “ thermodynamical )’ potential difference (E) measured acrossthe surface is the total P.D. due to both layers. On the otherhand, electrokinetic measurements give the P.D. (l) across thatpart of the interface which is capable of displacement parallelto the surface, i.e., the .‘ diffuse ’) layer. The two P.D.’s have beenmeasured by H. Freundlich and co-workers,B at glass surfaces in avariety of solutions. Not only do they differ, but they may be ofopposite sign. Whilst the E P.D. is not much influenced by thesalt concentration, the 4-c curves are very characteristic for saltsof different types.There is no satisfactory theory of the relationbetween [ and C, since Stern’s equation cannot be applied to actualcases.H. Lachs and J. Kronman,’ however, find that these potentialscan only be reproduced within 14%. It is to be expected thatonly P.D.’s which depend on a thermodynamical equilibriumbetween the two phases are definite and reproducible (thus a metalonly gives a definite P.D. in solution containing its ions), and theabove cases do not come within this category. Measurements ofc and 1 a t the surfaces of slightly soluble salts and solutions con-taining their ions are therefore of greater value. A. Gyemant *has made such measurements with barium sulphate, and R. Labeswith barium sulphate, zinc oxalate, lead chromate, and silver1 2.physikal. Chcm., 1903, 45, 307; A , , 1904, ii, 18.J. Physique, 1910, [iv], 9, 457; Ann. Physique, 1917, [ix], 7, 129; A.,Phil. Mag., 1913, [vi], 25, 47.5. Also K. F. Herzfeld, Physikal. Z . , 1920,* A. Frumkin, Phil. Mag., 1920, [vi], 40, 376; A . , 1920, ii, 578; 0. K.1917, ii, 291.21, 28.Rice, J . Physical Chcm., 1926, 30, 1501.2. Elektrochem., 1924, 30, 508.H. Freundlich and P. Rona, Sitzungsber. Preuss. dkad. Wiss. Berlin,1920, 20, 397 ; H. Freundlich and G. Ettisch, 2. phys-ikal. Chem., 1925, 116,401 ; A., 1925, ii, 873. Summary of results by H. Freundlich, Trans. FaradaySOC., 1926, 22, 440.Bull. Int. Acad. Polonaise, 1925, A , 289; A., 1926, 803.* 2. physikal. Chem., 1922,103, 260 ; d., 1923, ii, 52.The 6 P.D. betweensolid salts and their solutions was first realised by F. Haber, Ann. Physik,1908, [iv], 26, 927 ; .4., 1908, ii, 802. A. Oyemant has discussed the theoryof ionic adsorption applied to such cases, 2. physikal. Chem., 1924,108, 387 :A., 1924, ii, 391.9 Ibid., 1925, 116, 1 ; A , , 1925, ii, 796GENERAL AND PHYSIUAL CHEMISTRY. 45chloride. The latter has worked out a detailed theory. Sinceions of opposite charge to the solid accumulate near the surface-and to a greater extent the greater their concentration in thesolution-the electrokinetic potential is small in concentratedsolutions. I n more dilute solutions, specific effects are observable,and in the absence of specific adsorption of ions, the theory indicatesthat an ion influences the electrokinetic potential the more thesmaller the solubility product of the salt which it forms with eitherof the component ions of the solid.This conclusion is confirmedby the experiments.A. Prumkin and associates have made measurements of theP.D. a t the surface of aqueous solutions by F. B. Kenrick’s method,1°in which the P.D. is measured between the solution flowing downthe inside wall of a cylindrical tube and a stream of a standardsolution flowing down its axis. In salt solutions,ll the outersurface is in nearly all cases negatively charged ; the predominanceof anions, thus indicated near the surface, is greater the less theirenergy of hydration, and the effect on the P.D. is in the sameorder. Similar measurements have been made with organic com-pounds.The results are in accordance with the orientation ofmolecules in the surface layer, and give valuable information asto their polarity. Aliphatic alcohols, esters, amines, etc.,12 increasethe positiveness of the surface owing to their orientation with therelatively positive alkyl groups outwards. Strong acids and neutralsalts have the opposite effect, owing to the greater attraction ofwater for cations than for the carboxyl group. I. Traube’s adsorptionrule (viz., that as the number of methyl groups increases in arith-metical progression, the adsorption from solutions of the sameconcentration increases roughly in geometrical progression) holdsalso for these P.D.’s. Aromatic compounds show similar relations.13The effect of methyl groups is, however, less than in aliphaticcompounds and the presence of polar groups in the nucleus mayreverse the effect.This method is only applicable when the surface equilibriumis quickly reached.A method has been devised l4 for use withla 2. physikal. C’hem., 1896, 19, 625; A., 1896, ii, 460.l 1 A. Frumkin, ibid., 1924,109,34 ; A., 1924, ii, 462. Compare A. Frumkin,8. Reichstein and R. Kulvarskaya, Kollcid Z., 1926, 40, 9 ; A., 1091. A.Frumkia and A. Donde (2. physilcal. Chent., 1926, 123, 339; A., 1104) findthat mercury can be substituted for the standard solution.A. Frumkin, ibid., 1924, 111, 190; A . , 1925, ii, 109.l3 A. Erumkin, A. Donde and R. Kulvarskaya, ibid., 1926, 123, 321; A.,1092.l4 A.Frumkin, ibid., 1925, 116, 485; A., 1926, ii, 873; Kolloid Z., 1924,35, 340; A . , 1925, ii, 544; Trans. Kurpcv. Inst. Chem. [Russia], 1925, No. 4,66; A., 1926, 109346 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.solutions giving insoluble unimolecular films, in which the P.D.is measured between the stationary solution and either a glowingwire or a wire containing some radioactive material, in order tomake the air-gap sufficiently conducting. In these cases, theP.D. is proportional to the amount adsorbed until a completeunimolecular layer is formed, after which it remains constant.has worked out an elaborate statistical theory ofthe surface charges of inorganic electrolyte solutions, and is ableto account for Frumkin's results. A. Garrison l6 has used a con-denser method to determine the surface charges of electrolytes.R. D.Kleeman and C. R. Pittsl7 have ako studied the sign ofthe charge furthest from the solution by another method. H. W.Gilbert and P. E. Shaw l8 have recently summarised the literatureon the determination of electric charges a t gas-liquid interfaces.The study of the surface phenomena of mercury in electrolyticsolutions promises to give particularly valuable information abouteIectrification a t surfaces and also about the effect of an electricfield on the constituents of the solution, for it is the unique casein which the P.D. can be varied a t will by polarisation and theeffects on the surface tension observed a t the same time. Theclassical equation of Gibbs and Helmholtz, dy/dV = - e, whichequates the rate of change of surface tension with applied P.D.to thecharge on the double layer e, has been obtained in numerous ways.R. K. Schofield19 has identified e with the amount of adsorbedmercury ions and has directly determined this amount by aningenious method, obtaining results in good agreement with theequation.lQa A. Frumkin 20 has discussed the effect of the adsorptionof anions and cations and of neutral capillary-active substances onthe electro-capillary curve. In the latter case, variations of surfacetension are given by dy = - e . dV - BTAdpA. The first termon the right represents the effect of electrification, the second(in which PA is the amount of adsorbed substance A , and pA itschemical potential in the solution) the lowering of surface tensionproduced by the capillary-active substance.Since ra is itself aW. Wessel1 5 Ann. Physik, 1925, [iv], 77, 21; A., 1925, ii, 795.16 J . Physical Chem., 1925, 29, 1617; A,, 1926, 130.1 7 Ibid., p. 608; A , , 1926, ii, 659.18 Proc. Physical Soc., 1925, 37, 196; A., 1925, ii, 798.10 Phil. Mag., 1926, [vii], 1, 641; A., 672; Trans. Faradcay Soo., 1926,22, 452. Compare A. Frumkin, Z. physika2. Chem., 1922, 103, 65; A . ,1923, ii, 64.1- W. A. Patrick and P. W. Bachman ( J . Physical Chem., 1926, 30, 134 ;A., 239) and J. E. Rosenburg and G. Stegeman (ibid., p. 1306 ; A,, 1201) alsohave investigated the adsorption of ions at the mercury surface.*o Phil. Nq., 1920, [vi], 40, 363, 375; A., 1920, ii, 678; also ref. (19)GENERAL AND PHYSICAL CHEMISTRY. 47function of V , this equation does not give the complete variationof y with V , Frumkin21 has applied the equation Ay=A log (Bcfl)for the lowering of surface tension produced by an active substanceand has obtained B as a function of the electric-field strength inthe form B = B,e+lRT, where 4s is the additional electrical workof adsorption due to the electric field, On this basis, the effectof amyl alcohol on the electro-capillary curve is satisfactorilyaccounted for. Capillary-active neutral substances in general onlylower the surface tension in the vicinity of the electro-capillarymaximum, i.e., when the electric field strength is low. The amountadsorbed is therefore diminished by increasing the P.D. a t theinterface in either direction. It has been found by direct measure-ment 22 that the adsorption of n-octoic acid a t the surface of silveriodide increases to a sharp maximum a t about the isoelectricpoint.0. K. Rice 23 has investigated the surface tension of chargedsurfaces, obtaining the expression dy/dV = - e - Eridpi/dV, inwhich the second tcrm represents the effect of the adsorption ofions (pi is the chemical potential in the superficial layer of ionsof the i t h kind). These terms are interpreted from the point ofview of electrostatic theory. A detailed analysis of the changesproduced by electrolytic polarisation a t the mercury surface andthe therinodynamical theory of their effects on the surface tensionhas been given by J. A. V. Butler.24 It is held that Gibbs’sequation by itself is inadequate to account for the electrocapillarycurves, an electrostatic effect in addition having to be taken intoaccount.dyldT‘ = - 2e - aHg.FHg. - Pd{SI’,dpz}/dT’,in which the first term represents the electrostatic effect, thesecond the effect of adsorbed mercury ions, the third the effect ofother adsorbed ions or molecules. I n the third term rs itselfvaries wi+.h Ti, and this variation can only be calculated by kineticmethods. An application of the theory of ionic adsorption isoutlined which accounts quantitatively for the electro-capillarycurves in iodide solutions and is capable of accounting qualitativelyfor all types of curves exhibited by salt solutions.0. K. Rice 25 has examined the application of various theoriesof the electrolytic double layer to the electro-capillary curves.Chapman’s equation 26 is inadequate. As an alternative to Stern’sThe following equation is obtained,2 1 Z. Physik, 1926, 35, 792; A,, 347.52 A. Frumkin and A. Obrutshewa, Nature, 1926,117, 790; A., 674.2s J. Physical Chem., 1926, 30, 1348; A., 1202.24 Proc. Roy. SOO., 1927, [A], 113, 694.25 J . Physical Chem., 1926, 30, 1501. 28 Compare ref. (3)48 ANNUAL REPORTS ON THE PROURESS OF CHEMISTRY.theory of a " condensed " double layer a t the surface and a diffuselayer in the solution, i t is suggested that the electronic charge inthe mercury may not reside entirely a t the surface but may also bediffuse. The two assumptions give very similar results but are notentirely adequate, E. Liebreich 27 has put forward evidence forthe belief that the maximum of the electro-capillary curve corre-sponds with the formation of hydroxide or basic salt on the surfaceof the mercury by cathodic polarisation. P. L. Usher2* hasexamined electro-capillary curves in salt solutions in connexionwith the electrokinetic behaviour.J E. COATES.J. A. V. RUTLER.27 Z. Elektrochem., 1926, 32, 162; A,, 478. Compare E. Liebreich and28 J. Phyeical Chem., 1926, 30, 954; A,, 803,W. Wiederholt, %bid., 1924, 30, 263; A , , 1925, ii, 44

ISSN:0365-6217    

DOI:10.1039/AR9262300011

出版商:RSC    

年代:1926

数据来源: RSC

摘要:

INORGANIC CHEMISTRY.THE Report for 1926 has been prepared in the same manner asprevious Reports and, to save space, the reader’s attention may bedirected to the remarks prefacing the Report for 1925, which areapplicable to this one also.Among subjects which appear to be of special interest are severalcases of apparent transmutation of elements (hydrogen to helium,inercury to gold, lead to mercury and thallium), further work onthe hydrides of boron, the discovery of the missing rare-earthelement (No, 61) ‘. illinium,” and a good deal of work on the effectsof intensive drying, noted in several parts of the Report.Atomic Weights.The technique previously developed for determiningthe density of oxygen has been applied to determine the normaldensity of helium.The value obtained is 0.17846 a t 0’ and760 nim. a t sea level in latitude 45”, g being taken as 980.398.Hence the atomic weight of helium is 4a000 with an experimentalerror affecting the 4th decimal on1y.lA flotation method has been utilised to compare thedensities of samples of boric oxide prepared from six boron mineralsfrom different parts of the world. The boric oxide beads weresealed in glass tubes with the same mixture of dry, inert, organicliquids of known density, and the temperature of flotation of thebeads in each sample was then observed. The mean density offused boric acid a t 18” is 1,7952. The densities of the severalsamples varied from 1.79711 to 1.79404, indicating variations inthe atomic weight of boron from 10.847 t o 10.788.The threesamples for which previous determinations of the ratio BCl, : 3Aghad given the values 10.841, 10.825, and 18.818, gave relative valuesdeduced from the densities 10.847, 10423, and 10.818.2Silicon. A similar flotation method, using glass floats of appro-priate density, previously calibrated by determination of theirflotation temperatures in a mixture of organic liquids of knowndensity, has been applied to compare the densities of, and hence the1 G. P. Baxter and H. W. Starkweather, Proc. Nut. Acod. Sci., 1925, 11,231; 1926,12, 20; A., 1925, ii, 1045; A,, 1926, 233.* H. V. A. Briscoe, P. L. Robinson, and G . E. Stephenson, J., 1926, 70;A., 219; compare Ann. Repvrte, 1926, 22, 43.Heliunz.Boron50 ANNUAL REPORTS ON TEE PROQRESS OF CHXMISTRY.atomic weights of the samples of silicon in, preparations of silicontetrachloride derived from five precisely known localities in Canada,the United States, Sweden, Scotland, and France, and subjectedto a rigorous purification by fractional distillation under exclusionof moisture, first a t atmospheric pressure and afterwards in avacuum.The extreme values for the atomic weight of silicondeduced from the densities of silicon tetrachloride are 28.058 and28.063, the maximum variation thus being one part in 6000 parts,and the probable error of individual relative values of the atomicweight considerably less than this. These results are held to showthat any variation in the atomic weight of silicon from differentsources is substantially less than one unit in the second decimalplace,3 and confirm and extend the conclusion deduced from pyknom-etric measurements of the density of tetraethylsilicane by Jaegerand Dijl~stra.~Chlorine.Determinations are recorded of the ratio AgCl : Ag,using samples of chlorine derived from the sea, from three mineralsof non-marine origin, viz., apatite, wernerite, and socialite, and froma meteorite. The mean value of the atomic weight for chlorine incommon salt and the three terrestrial minerals is 35.457 & 0.0002,whilst that of the meteoritic chlorine is 35.458 5 0-0005. Thesedeterminations afford further evidence, much more precise thanthat hitherto available, that the atomic weight of chlorine doesnot vary with its source.6Metallic germanium derived from the germaniumtetrachloride previously used for atomic-weight determinations,Gwas converted into germanium tetrabromide, and this compound,after purification by 13 fractional distillations in a vacuum, wasused for determinations of the ratios GeBr, : 4Ag, GeBr, : 4AgBr.The mean of 32 analyses gave Ge = 72.60, a value identical withthat given by analysis of the tetrachloride.'Silver. A thorough investigation has shown that silver oxideis much more stable than has hitherto been supposed, and that,when it is prepared by precipitating silver nitrate with baryta underrigid exclusion of organic matter and carbon dioxide, it may be3 P.L. Robinson and H. C. Smith, Nature, 1926, 118, 303; A., 999; J.,1926, 1262; A., 771; H.V. A. Briscoe and P. L. Robinson, Nature, 1926,117, 377; A,, 331.4 F. M. Jaeger, 2. Elektrochem., 1926, 32, 328; A., 870; compare Ann.Reports, 1925, 22, 44.6 W. D. Harkins and S. B. Stone, J. Amer. Chem. SOC., 1926, 48, 938;A., 553.6 Ann. Reports, 1924, 21, 28.7 G. P. Baxter and W. C . Cooper, J. Phy&cal Chem., 1925, 29, 1364; A.,Cermaniurn.1926, 5INORGANIC CHEMISTRY. 51heated in a current of pure air at 120' for a week without decom-position, and thereafter will yield a white chloride on treatmentwith hydrochloric acid. By heating pure silver oxide thus pre-pared in a silica tube a t 350---100', in a current of pure dry air, 6direct determinations were made of the ratio Ag,O : Ag, giving amean value for the atomic weight of silver Ag = 107.864 f 0.0013.The original paper must be consulted for interesting details of thepreliminary investigation into the stability of silver oxide and of theapparatus and methods used in the actual determinations.8 Ninedeterminations of the silver remaining after ignition of silvercarbonate, prepared and dried under the conditions found to giveB minimum of decomposition, gave a mean value for the atomicweight of silver Ag = 107.86.*Lead.I n the course of unsuccessful attempts to obtain someseparation of the isotopes present in ordinary lead by irreversiblevolatilisation and by the Grignard process, 18 values for the ratioPbCl, :2Ag were obtained, giving a mean value for the atomicweight of lead Pb = 207.217 f <O.OO1.loFour determinations of the ratio PbC1, : 2Ag upon lead extractedfrom a specimen of uraninite from the Black Hills, South Dakota,gave a mean value for the atomic weight of lead Pb = 206.07.When a correction is applied for the known thorium content of themineral, it appears that the atomic weight of uranium-lead in thisspecimen is Pb = 206-02. It is of interest that the high lead-uranium ratio, 0.23, of this relatively pure uranium-lead indicatesan age for the mineral of a t least 1500 million years.llTitanium.I n continuation of work previously reported, 17determinations of the ratio TiCl, : 4Ag, made on material from thelater stages of the fractionation of the tetrachloride, yielded resultsfor the atomic weight of titanium lying within the limits 47483-47.922 and giving the mean value Ti = 47.90.11a.GTOUP 0.A development in the methods of detecting helium hss affordedevidence of the production of that gas from hydrogen.By remov-ing the relatively condensable gases with charcoal and liquid air,burning hydrogen with excess of oxygen on a platinum or palladiumcatalyst, absorbing the residual oxygen with charcoal, and examining* H. L. Riley and H. B. Baker, J . , 1926, 2510; A., 1190.9 G. H. Jeffrey and A. W. Warrington, Chem. News, 1926, 132, 373; A.,T. W. Richards, H. S. King, and L. P. HaI1, J . Amer. Chem. Soc., 1926,T. W. Richards and L. P. HalI, i b d , p. 704; A,, 449.11s G. P. Baxter and A. Q. ButIer, ibid., p. 3117; compare Ann. Reports,694.qS, 1530; A,, 771.1923, 20, 3062 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the residual gas spectroscopically in a minute glass capillary, itis possible to detect quantities of helium as small as 10-8 or 10-9 C.C.and thus to detect the gas evolved from active thorium precipitates,and determine the quantity in quite small samples of natural gas.When hydrogen free from helium is passed over heated palladium,the issuing gas is found to contain helium, and the quantity of heliumappears to be increased when the hydrogen is allowed to remainin contact with palladium-black, spongy palladium, or palladisedasbestos a t the ordinary temperature.Although the behaviour ofthe catalyst is somewhat irregular, and its activity diminishes withtime, there is a rough proportionality between the duration ofcontact of the hydrogen with the metal and the quantity of heliumfound thereafter.Catalysts inactive to hydrogen, and occasionallycatalysts which readily absorb hydrogen, do not yield helium, but,in general, a catalyst active towards hydrogen does produce helium,A catalyst which has become inert may be revived in the usualmanner, and may then produce helium. Specimens of finely.divided palladium which have been preserved for a time a t theordinary temperature always yield helium on heating. There is,of course, some neon in this gas, but the ratio of helium to neon isusually much greater than that in air. These observations all leadto the conclusion that the palladium in this case acts purely as acatalyst for the conversion of hydrogen into helium, and this viewis confirmed by the further observation that a similar, although less,effect is produced by platinum.12Measurements of the surface tension of liquid helium in contactwith its saturated vapour by the method of capillary rise have shownthat the molecular surface tension increases linearly with fall oftemperature down to 2.4" Abs., and thereafter approaches a constantvalue in the neighbourhood of 1.5" Absi.13 By observing the absolutetemperatures and pressures a t which a tube system, containingliquid helium, became blocked, it has been inferred that the fusioncurve of helium is described by the following points : 1.l0, 2 6 atm.;2.2") 50 atm, ; 3-2") 86 atm. ; 4.2") 150 atm. When helium was frozenin a glass tube, no boundary surface was visible between the solidand liquid phases, whence i t appears that the refractive indices ofsolid and liquid helium must be closely ~imi1ar.l~ It has been shownthat quartz glass is permeable to helium under a pressure of 100 atm.a t laboratory temperatures, whereas under the same experimentalconditions no permeability to hydrogen could be detected.1512 F.Paneth and K. Peters, Ber., 1926, 59, [B], 2039; A., 1077.13 A. T. van Urk, W. H. Keesom, and H. K. Onnes, Proc. K. Akad. Wetenach.l4 W. H . Keesom, Compt. rend., 1926, 188, 26, 189; A., 892, 893.H. M. Efsey, J . Amer. Chem. Soc., 1926, 48, 1600; A., 895.Amsterdam, 1925, 28, 958; A,, 1926, 568INORGANIC CHEMISTRY. 53Croup I.Some interesting work is reported on the reduction of aqueoussolutions of metallic salts by hydrogen under pressure.Withsolutions containing 3-30% of platinum chloride, the yield ofplatinum in unit time increases with temperature and with pressureof hydrogen, whilst the proportion of the total platinum precipit-ated increases with diminishing initial concentration of the solution.Presence of iron and nickel salts and mineral acids greatly retardsor inhibits the reduction.16 The action of compressed hydrogenon hot copper sulphate solution yields, first the basic saltCuSOp,2Cu( OH),, then cuprous oxide, and ultimately copper, thequantity of which increases with the amount of free sulphuric acidpresent. At 150°, there is some reduction of sulphuric acid andthis facilitates the separation of basic salts and cuprous oxide;a t higher temperatures copper sulphide is produced.This reduc-tion of sulphuric acid is accelerated by the precipitated copper.Chromic acid, alone or in the presence of sulphuric acid, is reducedt o the oxide, Cr,O,,H,O ; whilst potassium dichromate, acidifiedwith sulphuric acid, a t 300" and 80 atm. of hydrogen, yields smallviolet-grey crystals of a salt, K20,2Cr,0,,3SO,,H,O, insoluble in acidor alkali. From nickel formate, under relatively drastic conditions,anhydrous, crystalline nickelous oxide is produced ; lower temper-atures and pressures give a quantitative yield of metallic nickel.Phosphoric acid is not reduced a t 350°, but lead hydrogen orthophos-phate is reduced to lead hydrogen phosphite, hypophosphorous acid,and colloidal lead oxide.Red phosphorus a t 200" and 90 atm. isconverted into black phosphorus, but under milder conditions ityields phosphine and phosphoric acid. Many other interestingreactions are described in the original papers.17A good deal of evidence converges on the view that many of theso-called metallic hydrides are in fact not stoicheiometric compoundsbut solid solutions approximating closely thereto. Even calciumhydride, usually regarded as a typical salt-like hydride of the typeformed by the alkali and alkaline-earth metals, is found to containless hydrogen than is required by the formula CaH,, and t o show,even a t 20", a measurable hydrogen pressure, steadily increasingwith time, even after 9 days. On removing hydrogen from calciumhydride, the substance slowly separates into two portions, oneapproximating closely to CaH,, the other poorer in hydrogen. Simi-larly, it is found that dry copper hydride always contains lesshydrogen than is required by the formula CuH and loses hydrogen16 V.Ipatiev and A. hdreevBki, C m p t . rend., 1926, 183, 51; A., 921.l 7 V. Ipatiev and others, Ber., 1926, 69, [B], 1412; A,, 921; V. N. Ipatievend B. A. Mouromtsev, Compt. rend., 1926, 183, 505; A., 111484 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.progressively when heated.18 Observations on the absorption ofhydrogen by praseodymium, neodymium, zirconium, and thorium,and on the dissociation of the products, indicate that these hydridesalso, as well as those of cerium and lanthanum, are solid solutionswhich, under favourable conditions, may approximate to, but neveractually attain, the composition and stability of stoicheiometriccompounds.lgA thorough investigation of the action of copper on concentratedsulphuric acid has shown that whilst a t all temperatures from 16"to 270" the completed reaction is represented by the equation Cu+2H,S04 --+ SO, + CuSO, + 2H,O, there actually occur at leastfour different reactions :(i) 5cu + 4H,SO, = cu,S + 3CuS0, + 4H,O ;(ii) Cu,S + 2H,SO, = CuS + CuSO, + 2H,O + SO, ;(iii) CuS + 2H,S04 = CuSO, + 2H,O + SO, + S ;(iv) S + 2H,SO, = 2H20 + 350,.In the temperature range 100-120°, action (i) is much more rapidthan actions (ii) and (iii) ; hence sulphide formation is particularlyevident.At 270", actions (ii) and (iii) are so rapid that the presenceof sulphides as intermediate compounds is not readily detected.The crystalline deposit formed is anhydrous copper sulphate, whichis white when formed a t high temperatures, but a t lower temper-atures is grey, owing to inclusion of black sulphides; micro-scopic examination of the crystals gave evidence that this salt isdimorphous.20Evidence is adduced that discrepancies in the literature relativeto basic copper sulphates are attributable to the formation of highlystable intermediate compounds, and that the basic salt obtained byboiling solutions of copper sulphate for a short time is5CuS04,9Cu( OH),,2H20.This salt can easily be produced in quantity if the acid producedon hydrolysis is removed as it is formed by interaction with sodiumnitrite present in the solution.On prolonged boiling with water,this basic salt or copper sulphate yields CuS04,2Cu(OH),. Byhydrolysis of copper sulphate in solutions over a small range of con-centration near saturation, a new basic salt, 2CuS04,Cu( OH),,4H20,was obtained which has apparently eluded previous observers owing toits decomposition by water. Two other basic salts, CuS04,3Cu( OH),and 2CuS04,3Cu( OH),, were recognised as definite compounds.1* a. F. Huttig, 2. angew. Chem., 1926, 39, 6 7 : A., 354; G. F. Huttig andF. Brodkorb, 2. anorg. Chem., 1926, 153, 235, 309; A., 694, 809; see alsoH. Miiller and A. J. Bradley, J ., 1926, 1670.A. Sieverts and E. Roell, ibid., 150. 261; 153, 289; A., 356, 810.*O C. W. Rogers, J., 1926, 264MORGANIU OHEMISTRY. 55The original paper contains a very thorough discussion of the wholeliterature of the basic copper sulphates in the light of the presentwork and merits careful study.21Reinvestigation of the cuprous alkali thiosulphates has disclosedthe existence of the ammonia compounds Cu,S20,,2K2S203,NH3 andCu,S203,Na2S,03,2NH,.22Silver perchlorate is unique among typical metallic salts in beingreadily soluble in toluene, the solution saturated a t 25' containing50.3% of the salt : below 22.6" the solid phase in equilibrium with thesolution is AgClO,,C,H,, and the solubility falls off rapidly a t lowertemperatures. These observations are incidental to an examinationof the ternary system-silver perchlorate-toluene-water-for theresults of which the original paper must be consulted.23Further application of the Steele-Grant microbalance and themethods previously described has shown that optimum concen-trations of chlorine exist for the chlorination of both fresh andpreviously-chlorinated silver films, that photochemical decom-position of silver chloride and silver iodide a m s may proceed to theextent of 94-95y0, and that there is no evidence of the formation ofsubchloride or ~ubiodide.~~Group I I .Compact masses of beryllium have been prepared by electrolysingthe double fluoride a t 1200" in a graphite pot with graphite anodespreviously impregnated with the salt.The rotating cathode has aberyllium tip held in a water-cooled holder and is slowly raised aselectrolysis proceeds: thus a solid rod of beryllium is obtained.The crude metal is free from impurities except about 0.05% each ofiron, carbon, aluminium, and magnesium and about 0.005~0 nitrogen;by sublimation in beryllia pots, carbide-free metal containing lessthan 0.02% iron was obtained. Beryllium has d 1-84 and m. p,about 1280" ; it takes a high polish, resists atmospheric corrosionwell, does not readily ignite, is non-ductile, and has a Brine11 hard-ness usually about 140 but in one annealed sublimate as low as 90.,lInvestigations of the viscosities of solutions of beryllium sulphate,selenate, and oxalate containing dissolved beryllia, and of theconductivities of neutral and basic solutions of beryllium chlorideCompare, however, H.T. S. Britton, ibid.,p. 2868.A. Benrath, H. Niehaus, H. Meekenstock, and H. Essers, 2. unwg.Chew., 1926, 151, 31; A., 367.A. E. Hill and F. W. Miller, J. Amr. Chern. Soc., 1925, 47, 2702; A.,1926, 26.E. J. Hastung, J., 1925,127, 2691; 1926, 1349; compare Ann. Repwta,1922, 19, 43; 1924, 21, 35.s1 A. C. V i v h , Trana. FurMEay Soc., 1926, 22, 211; A,, 1114.a1 G. Fowles, J., 1926, 184556 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.and oxalate, yield results consistent with the view that the sulphateand selenate solutions contain a complex cation, Be,xBeO, where xon the whole is less than 4. In the course of this work, berylliumbensenesulphnate and p-bluenesulphonate were obtained as crystal-line salts with 4H,0.32By using a crucible, stirrer, and thermometer-sheath made of a5 : 2 mixture of bole and alumina, which softens only a t 1560" andis not attacked by the melt, it has been possible to make a thermalanalysis of the calcium and magnesium silicides.Two calciumsilicides, CaSi, m. p. 1220", and CaSi,, m. p. 1020°, are formed,and there is some evidence for a third compound, Ca,Si, m. p. 920".Both CaSi and CaSi, are decomposed by water, yielding spontane-ously inflammable silicon hydrides. Thermal analysis of mag-nesium-silicon melts shows only the compound Mg,Si, m. p. 1070",already known, but when the melt is rapidly cooled from above1050", a second silicide, MgSi, is obtained, which is also formed byvolatilisation of magnesium when Mg,Si is kept at temperaturesabove 600".Above 1100", both silicides dissociate, yielding theelements .aA thermometric study of the setting of plaster of Paris, in whichthe maximum on the time-temperature curve was taken as thetime of setting, shows that setting occurs in two stages : (a) aslightly exothermic absorption with contraction in volume, and ( 6 ) amarkedly exothermic reaction between the absorbed liquid and theabsorbent with an attendant increase in volume. The acceleratingeffect of cations in this change is in the order K>NH,>Na>Li;Zn = Cu>Mg : the decelerating effect of anions is in the orderI > NO,> Br >Calcium sulphate, on being heated with carbon at 900" 0s withhydrogen a t 600400", yields calcium sulphide, but above 900" thisproduct reacts with undecomposed sulphate, yielding lime andsulphur dioxide ; a t higher temperatures, interaction occursbetween carbon monoxide and sulphur dioxide, producing sulphur,with carbon oxysulphide as a by-product.35 Simple dissociation ofcalcium sulphate begins at 960" and the dissociation pressure reaches97 mm.a t 1230"; in an equimolecular mixture with amorphoussilica, dissociation begins at 870" and produces a pressure of 817 mm.8% N. V. Sidgwick and N. B. Lewis, J . , 1926, 1287; see general discussionof co-ordinated additive compounds of beryllium, R. Fricke, 2. angew. Cltem.,1926, 39, 317; R . Fricke and 0. Rode, 2. anorg.Chem., 1926, 152, 347;R. Fricke and L. Havestadt, ibid., p. 357; A., 368, 694, 695.33 L. Wohler and 0. Schliephake, ibid., 1926, 151, 1; A., 368.a4 H. A. Neville, J . Physical Chem., 1926, 30, 1037; A,, 899.36 J. Zawadzki, J. Konarzewski, W. J. Lichtenstein, S. Szymankiewicz,and J. Wachsztejnski, Rocz. Chem., 1926, 6, 120, 236; A., 923INORGANIC CHEMISTRY. 57a t 1280". The effect of alumina and ferric oxide has also beenstudied.3sWhen baryta is heated with cupric sulphide or lead sulphide itbrings about a partial reduction to metal (72;/, in 1 hr. a t 1150"in the case of copper) according to the equations of the type : 37CuS + BaO --+ CuO + BaS ; 4CuO + Bas -+ BaSO, + 4Cu.From a study of the solubility curves and the composition of thesolid phases in the system M,O,-BaO-H,O a t 20°, only two bariumaluminates could be isolated, wiz., 2BaO,A1,O3,5H,O, stable insolutions containing from 3.5 to 2.10,', of barium oxide, andBa0,A1,03,6H,0, stable in concentrations of from 2.1 to 1.2% ofbarium oxide. Sevcral coinpounds described in the literature werenot obtained.The former compound is rapidly decomposed by waterinto the latter, which is also decomposed by a large excess of waterinto barium hydroxide and gelatinous aluminium hydroxide.38The cooling curves of calcium amalgams and their microstructureswhen frozen on glass surfaces are consistent with the existence ofthree compounds, CaHg,, CaHg5, and CaHg,,, and the second ofthese may be obtained in relatively large crystals by pouring theamalgams into water.39Stock has directed attention to the possibility that workers exposedto the vapour given 08 by mercury a t laboratory temperatures maycontract very serious mercury poisoning, unless there is an ex-tremely good system of ventilation.The condition of chronicpoisoning thus developed can only be cured by several years'abstention from all work involving the use of mercury. Someworkers deny the possibility of such poisoning, but others can con-firm Stock's experience>O It seems possible that much depends onpersonal idiosyncrasy, so that, whilst some persons are relativelyimmune, others may in fact contract chronic mercurial poisoningunder ordinary laboratory conditions ; if so, a clear case exists forthe exercise of greater precaution than has been customary in theuse of mercury.a6 (Mlle.) G.Marchal, J. Chim. phys., 1926, 23, 38; A., 359; BUZZ. SOC.chim., 1926, [iv], 39, 401; A,, 487.37 W. Biltz and E. von Muhlendahl, 2. anorg. Chem., 1925, 150, 1 ; A.,1926, 136; I. A. Hedvall, Svensk Kem. Tidskr., 1923, 37, 166; from Chem.Zeatr., 1925, 11, 1946; J. A. Hedvall and E. Norstrom, 2. anorg. Chem.,1926, 154, 1 ; A., 368, 695.sB G. Malquori, Uazzetta, 1926, 56, 5 1 ; A,, 810.39 A. Eilert, 2. anorg. Chem., 1926, 161, 96; A,, 356.40 A. Stock, 2. angezo. Chem., 1926, 39, 461; A. Schmidt, ibid., p. 786;G . Pinkus, ibid., p. 7 8 7 ; H. Reihlen, tbid., p. 788; F. Gradenwitz, zbid., p.788; L. Wolff,ibid., p. 789; A. Stock, ibid., p. 790; K. Hofer, ibid., p.1123;A,, 707, 815, 122358 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.I n heating mercury in a sealed silica bomb, a marked distinctionbetween the liquid and vapour phases was observed immediatelybefore the bomb burst above 1000" ; hence the critical temperatureof mercury certainly lies above that temperature.41By using the metal as the liquid in a V-shaped silica manometertube, closed a t one end by a sealed-in thermocouple sheath andopen a t the other end t o a measured applied pressure of nitrogen,measurements have been made of the vapour pressures of mercuryfrom 200" (14 mm.) to 397.5" (1490 mm.), of cadmium from 500"(14 mm.) to 836" (1536 mm.), and of zinc from 625" (16 mm.) to982' (1517 mm.).43Group I I I .Some interesting additions have been made to our knowledge ofthe boron hydrides. Pure diborane has d-112' 0.447 (liquid), d-183'0.577 (solid), and slowly decomposes a t the ordinary temperature,yielding pentaboron hydride, B5Hll, b. p.0°/57 mm., m. p. about- 129". Unlike the higher hydrides, diborane is not oxidised by airor oxygen a t 15": it is hydrolysed by excess of water to boricacid and hydrogen. Ammonia with B5H1, yields hydrogen and scompound, B,H,(NH,),, which closely resembles that formed fromB5H,.43 This ammine when heated gives a compound, B,N,H,.Diborane and ammonia a t 15" give an additive compound,B,H6,(NH3),, which in solution behaves as an alkaline solution ofdiborane, when,heated in a sealed tube gives B,N3H,, and reactswith hydrogen chloride according to the scheme : B,H6(NH3), +2HC1 = B,H,Cl,(NH,), + 2H,. The action of ammonia ondiborane a t about 200" leads to the replacement of the hydrogenatoms by amino- or imino-groups, SO that when excess of ammonia,is used, the ultimate product is boroimide, B,(PU'H),.If theammine, B,H,(NH,),, is similarly heated, an analogous actionoccurs, but the amount of ammonia available is insufficient forcomplete replacement of the hydrogen atoms, and the main and-onlyvolatile product is the compound B3N3H,, mixed with non-volatilecondensed substances of composition between (BNH,), and (BNH),.The compound B3N,H6 has b. p. 0"/84.8 mm., m. p. -58.0", d-651.00 (solid), d-57' 0.898 (liquid), do' 0.824 (liquid), and is unusuallystable. At a high temperature, it decomposes into the compound(BNH), and hydrogen.It is indifferent to oxygen. In cold water,it dissolves to an initially neutral solution, which gradually becomesalkaline ; warm water causes quantitative hydrolysis t o boric acid,4 1 L. A. Sayce and H. V. A. Briscoe, J., 1926, 957.4 1 C. H. M. Jenkins, Proo. Roy. Soc., 1926, [A], 110, 456; A., 333.'3 Ann. Report.?, 1924, 21, 37; compare {bid., 1923, 20, 38INORGANIC CHEMISTRY. 59ammonia, and hydrogen. Ice-cold water yields the hydmte,B,N3H6(H20),, which is converted by anhydrous hydrogen chlorideinto the compound, B3N3H,Cl,(H,0),, and hydrogen. The sub-stance B,N3H, and hydrogen chloride slowly yield the non-volatilecompound, B3N3H6(HC1),. Ammonia is absorbed by the compoundB,N,H,, but the reaction appears complex.The behaviour of theNHvBH compound is best expressed by the constitution BH<NH,BH>NH.The action of iodine on diborane affords mainly boron tri-iodide,m. p. 48-1", and oily products. Diborane is readily converted byhydrogen iodide in the absence of a catalyst a t 50" into the unstableiodo-derivative, B,H,I, m. p. -110", b. p. 0"/78 mm., 2.0(solid), d-loS. 1.8 (liquid). Even a t low temperatures it decom-poses moderately rapidly into diborane and boron tri-iodide. It israpidly and quantitatively hydrolysed by water to boric acid,hydrogen iodide, and hydrogen. It is converted by sodium amal-gam a t -35" into the hydride, E4H10, for which the constitutionBH,-BH,*BH,*BH, is rendered probable if the '' ethane " structurefor diborane be accepted.A study of the infra-red absorptionspectrum of diborane and its X-ray analysis affords strong evidencefor the constitution BH,*BH,, and the following structures areinferred €or the other hydrides : B,H, = BH,.[BH],*BH, ; B5H,1=BH,-[BH],*BH,.A modified nomenclature for the boron hydrides is suggested,according to which the term borane is restricted to the "limithydrides " containing tervalent boron, e . g., B2H, = diborane,B3H5 = triborane, B,,H,, = decaborane. The hydrides richer inhydrogen (the only hydrides already isolated) are termed '' hydro-boranes," thus, B,H,, dihydrodiborane ; B,H,, dihydropentaborane ;B5Hl1, tetrahydropentaborane.&Boron sulphide is prepared by heating boric oxide with aluminiumsulphide in a current of nitrogen a t 1200-1300" : silicon disulphide(m.p. 1090", d 2.02) is similarly obtained when sand is substitutedfor boric oxide and is separable from accompanying silicon mono-sulphide by reason of its different ~ o l a t i l i t y . ~ ~The freezing-point diagram of the system boron trifluoride-hydrogen sulphide shows two eutectics a t -148" and -140", with22% and 5374, of hydrogen sulphide, respectively, between whichlies a maximum a t -137" indicating the existence of a compoundBF,,H,S which is apparently much dissociated a t its melting point44 A. Stock and E. Pohland, Bw., 1926, 59, [B], 2210, 2215, 2223; A.46 E. Tiede and M. Thimann, ibid., p. 1703; A,, 1112.BH3*BH2.BH*BH,*BH3 ; BGH1, = BH3fBHI4*BH3 ; B1,HId =Stock, ibid., p.2226; A., 1217, 121860 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.and should therefore not hinder the separation of the constituentsby fractional di~tillation.~~By rapid manipulation and exact adherence to specified con-ditions, aluminium hydroxide is obtained in three forms, c(, p, andy, which behave as distinct chemidal compounds, all of the formulaAl(OH),. By heating any one of these in a sealed tube at 250"with 10% ammonia, aluminium metahydroxide, AlO.OH, isobtained, having neither basic nor acidic properties but showingremarkable ability to adsorb enzymes ~electively.~'Several fluoroaluminates have been prepared and all these can berepresented, in conformity with other known aluminium compounds,with a.co-ordination number of 6, if in certain cases the nucleusis doubled, e . g., [F,Al<~>AlF4](N2H4),. A similar mode offormulation is applicable to a new potassium aluminium fluoride,A1F,,2KF,2H2O, and also t o a number of complex organic fluoridesof iron and chromium.48Thallium metasilicate, Tl,SiO,, is obtained as a white, amorphousprecipitate when a 4% solution of sodium metasilicate is slowlyadded to a solution containing 20,/; of thallous nitrate and 4% ofthallous hydroxide. An excess of thallous hydroxide must alwaysbe present, as the silicate readily undergoes hydrolysis. Thalliumorthosilicate, Tl4SiO4, is prepared (i) by adding a concentratedsolution of sodium metasilicate to a boiling 16.5% solution ofthallous hydroxide, a crystalline, canary-yellow precipitate beingobtained] which consists of the orthosilicate together with a littlemetasilicate ; (ii) by boiling thallium metasilicate with an excess of0-75N-thallous hydroxide solution ; (iii) by shaking finely-divided,precipitated silica with an excess of thallous hydroxide solution.Both the above thallium silicates are anhydrous] in contradistinctionto the metasilicates of sodium and lithium, which contain 9 mols.and 1 mol.of water, respecti~ely.~~Cerium, lanthanum, praseodymium, neodymium, and samariumhave been prepared as chemically pure metals by electrolysis ofthe fused chlorides in graphite cells, using graphite anodes.5046 A. F. 0. Germann and H. S. Booth, J. Physical Chem., 1926, 30, 369;A., 475.4 7 R.Willstatter, H. Kraut, and 0. Erbacher, Bet., 1025, 58, [BJ, 2448,2458; A., 1926, 34, 35.4 * H. Weinland, I. Lang, and H. Filrentscher, 2. anorg. Chem., 1925, 150,47; A,, 1936, 136.49 K. A. Vesterberg and C . U. Willers, Arhv Kemi, Mzn., Geol., 1926, 9,No. 26, 1; A., 695.E. E. Schumacher and J. E. Harris, J. Amer. Chem. Soc., 1926, 48,3108; see also, for the similar preparation of yttrium, A. P. 'Thompson,1%'. B. Holton, and H. C . Kremers, Tram. Amer. Electrochem., Soc., 1926, 49,161; A., 489INORGANIC CHEMISTRY. 61Further work has confirmed the individuality of the black oxide ofpraseodymium, Pr,O,,, which has d20' 6-61, and is not dissociated upt o 900" : it is regarded as a salt-like compound of R,O, with a higher0xide.~1Persistence in the search for element 61 has been rewarded bysuccess.Examination of the L-series X-ray lines of carefully puri-fied samples of rare earths showed a single faint line in the correctposition for L, 61.52 Fractional crystallisation of the cerium earthsas the magnesium double nitrates concentrates element 61 betweenneodymium and samarium, both having broad absorption bandscapable of masking any bands due to element 61, and fails to give asufficient concentration of this element for certain detection by theX-ray spectrum. If, however, these earths be fractionated as thebromates, element 61 is separated from neodymium and samariumby terbium and gadolinium, respectively. Terbium has but oneabsorption band and gadolinium has none ; hence it became possibleto observe faint bands a t 6700 and 5905 A.and stronger bands a t5830,5816, and 4520 if. attributed to the new element. The X-rayemission spectra of the samples showing these bands gave linescorresponding closely with the calculated positions for La,, and LB,,of element 61 ; the authors therefore claim to have discovered thiselement and propose for it the name " illinium." 53Group I V .Pure carbon tetrafluoride has been isolated by liquefying andfractionating the gases evolved a t a carbon anode used in theelectrolysis of fused beryllium fluoride; it differs from the com-pounds previously described as carbon tetrafluoride, which wereprobably mixtures. It has b. p. -150°, do' 3.034 (air = l),M 87-4, is decomposed by sodium at 500", by calcium at 600°, andundergoes partial dissociation a t 1100'.54Further work on the melting point of graphite, with an improvedapparatus in which higher pressures of argon and a closer approxim.ation to black-body )' radiation could be obtained, has given them. p. 3845" & 45' Abs., and shorn that there is no systematicvariation of m. p. over the pressure range 2-9 atm.655 1 W. Prandtl and K. Huttner, 2. anopg. Chem., 1926, 149, 236; A., 1926,137; compare Ann. Reports, 1924, 21, 40.52 C. J. Lapp, R. A. Rogers, and B. S. Hopkins, Physical Rev., 1925, [ii],25, 106; A., 1926, 1083; compare Ann. R e p r f s , 1924, 21, 39.53 J. A. Harris and B. S. Hopkins, J . Amer. Chem. SOC., 1926, 48, 1585;A., 810; J. A. Harris, L.F. Yntema, and B. S. Hopkins, aid., p. 1594; A.,780; compare L. Rolla and L. Fcrnandes, Qazzetta, 1926,58, 435; A,, 1083;13. Brauner, Nature, 1926, 118, 84; A., 780.54 P. Lebeau and A, Damiens, Compt. rend., 1926, 182, 1340; A., 710.6 6 E. Ryschkewitsch and F. Merck, 2. Elelctrochem., 1926, 32, 42; A,,232; compare H. Herbst, Phy9ikaZ. Z., 1926, 27, 366; A., 67062 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.In the presence of finely-divided palladium and absence of air,carbon monoxide is oxidised by water to carbon dioxide, withsimultaneous production of palladium hydride. Owing to thoisolation, in previous work, of small amounts of barium formate,it has been assumed that the primary action consisted in the additionof water to carbon monoxide, with formation of formic acid, which issubsequently decomposed into carbon dioxide and hydrogen.Theexperimental conditions have therefore been arranged in such amanner as to remove formic acid, if produced by hydration of carbonmonoxide, from the dehydrogenating action of palladium, using forthis reason alkaline solutions containing a sufficient amount of ethylalcohol; the presence of alcohol or sodium hydroxide has noinfluence on the ‘‘ oxygen-free combustion,’’ of carbon monoxide.Under these conditions, carbonate is immediately formed in thesolution, and therefore must be produced directly from carbonmonoxide; its production is accompanied by an increase in thehydrogen content of the palladium. Sodium formate, added beforethe experiment, is found unchanged in amount a t its conclusion.The production of carbonate is invariably less, and that of hydrogengreater, than corresponds with the volume of carbon monoxideabsorbed.This is caused by the very slow action of palladium onethyl alcohol, from which hydrogen is withdrawn, with productionof acetaldehyde, which, however, never Ieads to that of recognisableamounts of carbon dioxide.56The energy of the spark discharge necessary to ignite mixtures ofcarbon monoxide (2 vols.) and oxygen (1 vol.) varies with themoisture content of the gases; for gases saturated at 17” andcontaining 2% of water the energy is 4.6 x 10-3 joule; for gasessaturated at O”, containing 0.6% of water vapour (by vol.) it is29.0 x lo3 joule ; when the gases are dried over calcium chlorideand contain 0.03% of water, it is 126 x lo9 joule; whilst after dry-ing the gases for 6 months over phosphorus pentoxide, the minimumenergy required for ignition is about 0.3 joule.When the gases aredry, the explosion is softer and at atmospheric pressure the reactionis incomplete, its extent depending partly upon the energy of thedischarge. At higher pressures, the gases are more readily ignitedand the action proceeds further, so that above 10 atm. ignition isinstantaneous and the reaction is complete. Spectrograms ofexplosion flames in dry mixtures at 25 atm. show a complete absenceof the steam lines characteristic of the ordinary combustion of carbonmonoxide .57W. Traube and W. Lmge (and, in part, R.Stahn, R. Justh, and P.Baumgarten), BeT., 1925,58, [B], 2773; A,, 1926,257; compare Ann. Repwts,1912, 9, 44.s 7 W. A. Bone and F. R. Weston, Proc. Roy. SOC., 1926, [ A ] , 110, 615;A,, 480; W. A. Bone, R. P. Fraser, and D. M. Newitt, ibid., p. 634; A., 480INORGAMU CHEMISTRY. 63It has been found that in the chlorination of ferro-silicon the yieldof silicon hexachloride may be increased somewhat by adding silicontetrachloride to the chlorine ; this is, of course, in accordance withMartin's conclusions as to the mechanism of this chIorinati~n.~~By gradually adding to liquid ammonia a solution of disiliconhexachloride in anhydrous ether, ammonium chloride and diaminodi-iminodisilane, NH,.Si(:NH).Si(:NH).NH,, are formed. At -10")this compound loses ammonia to form polymeric tri-iminodisilane,Sf(iNH)>NH, which is stable at the ordinary temperature but de-Si(.NHIcomposes above 400" with some formation of silicocyanogen, Si,N,.These compounds are extremely sensitive to oxygen and moisture.From the products of the action of magnesium phenyl bromide ondisilicon hexachloride, dichlorodiphenylmonosilane, SiPh,Cl,, b.p.166"/17 mm., has been is0lated.~9In the course of further experiments upon silicic acids, the curiousobservation has been made that a certain form of silicic acid isvolatile in steam.60Pure germanochloroform has been prepared by the action ofhydrogen chloride on germanium dichloride; it has m. p. -71")b. p. 75*2", dw 1.93, and the vapour pressure has been measuredover the range -25" to 78.3".Decomposition of the compoundbegins a t 140" and is rapid a t 170") a t first by dissociation to yieldGeCI, + HC1, later to give the tetrachloride and metallic germanium.It is oxidised, even a t 0") by oxygen, probably according to thescheme : 4GeHC1, + 0, = 2GeC1, + 2GeC1, + 2H20.61 German-ium tetrachloride when pure, or in ethereal solution, reacts with dryammonia to give hexamminogermanic chloride, [Ge,GNH,]Cl,, as awhite powder which has no appreciable ammonia pressure a t theordinary temperature and may be kept for some days over con-centrated sulphuric acid without loss of weight. In aqueoussolution or in moist air it is slowly hydrolysed forming germanichydroxide. When the solid is treated a t 0' with ammonia at 3 atm.,it forms a second ammine, GeCl,,lGNH,, as a colourless liquidhaving an ammonia pressure of 760 mm. a t -4".Compoundsanalogous to the hexammine have been obtained with mono-, di-,and tri-ethylamines, propylamine, and butylamine.62Tertiary stannous phosphate, Sn,(PO,),, is a white, amorphousJ. I3. Quig and J. A. Wilkinson, J . Amer. Citem. Soc., 1926, 48, 902;A,, 589; compare G. Martin, J., 1914, 105, 2836.68 R. Schwarz and W. Sexauer, Ber., 1926, 59, [B], 333; A,, 369.6o R. Willstatter, H. Kraub, and K. Lobinger, ibid., 1925, 58, [B], 2462;L. M. Dennis, W. R. Orndorff, and D. L. Tabern, J. Pkysical Chem.,A., 1926, 36.1926, 30, 1049; A., 924.Oa W. Pugh and J. S. Thomas, J., 1926, 1051; A., 69564 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.powder, 4Z4* 3.823, insoluble in water, but soluble in mineralacids and alkali hydroxides ; it is produced by adding a 10% solu-tion of disodium hydrogen phosphate to a cold lo?/, solution ofstannous sulphate containing a little sulphuric acid.Stannoushydrogen phosphate, SnHPO,, crystallises in colourless tablets,d::''" 3476, from the solution obtained by dissolving granulatedtin in phosphoric acid (d 1.23), or in small, silky crystals on addingwater to a solution obtained by dissolving tin in phosphoric acid(d 1.5). Stannous dihydrogen phosphate, Sn(H,PO,),, results onheating the previous salt with phosphoric acid a t 140" and coolingthe solution over phosphoric oxide ; it crystallises in the form ofhighly refractive rhombs, dF'80 3.167, which are readily decom-posed by water.Stannous pyrophosphate, Sn,P,O,, is obtained asa white powder, 4.009, when the monohydrogen phosphate isheated a t 380-400" in a current of carbon dioxide. Stannousmetaphosphate, Sn(PO,),, is a white, glassy mass, d:Fg 3038, formedby heating the dihydrogen phosphate a t 390" in a current of carbondioxide. The stannous phosphates are more readily hydrolyseclthan the corresponding lead compounds, but otherwise are relativelystable.63Pure zirconium metal has becn obtained by preparing the puretetraiodide, resubliming it in a closed apparatus, and volatilisingit a t 600" in a vessel containing a fine tungsten wire heated electric-ally to 1800". Under these conditions, the iodide dissociates andpure zirconium is deposited as a rod, of which the tungsten wireforms only O.Olyo by volume.It has m. p. 2200" Abs., d 6.5, iscomparable with copper in ductility, and retains its lustre in air a tthe ordinary temperature but is superficially oxidised a t hightemperatures.64A new method of separating hafnium from zirconium makesuse of the fact that freshly-precipitated zirconium phosphate issoluble in oxalic acid and, on adding hydrochloric or sulphuricacid, is reprecipitated in a form which is readily filtered and affords acomparatively rapid separation of the hafnium in the precipitates.100 Kg. of a preparation containing 476% of zirconium and less than0.5% of hafnium were treated, and after 26 fractionations hafniumcontaining not more than 1% of zirconium was obtained.Thehafnium content of each fraction was determined with an X-rayspectrograph and confirmed chemically at intervals. This methodof separation has the advantages over fractional crystallisation ofthe double fluorides that it is more rapid, and that the hafniumA., 585.Is K. Jablczynslii and IY. Wiyckovslii, 2. anorg. Chem., 1926, 152, 207;J. L1. de Boer and J. D. Fast, ibid., 158, 1; A,, 699INORGANIC CHEMISTRY. 65accumulates in the less instead of in the more soluble fraction.From the pure hafnium phosphate, the metal (d 12.1) was preparedvia the hydroxide, oxide, chloride, metal, iodide, metal.65Some most interesting work is reported by Smits. A quartzapparatus, resembling a mercury-arc lamp but heated externally bygas-burners, was filled with molten lead of the highest purity andrun as a lead-arc lamp, in which, by rocking the tube, the arc wasmade and broken several times per second.At first, the lampshowed the lead spectrum only, but after running a t 80 volts and40 amp. for 10 hours, the spectrum of the light emitted showedstrong lines of mercury and thallium, and in experiments in whichsparking was employed to obtain high current densities, spectrashowing all the principal lines of mercury were obtained. In otherexperiments, a heavy spark-discharge between lead electrodesimmersed in carbon disulphide produced a fine deposit of dispersedlead. This lead was collected and heated in air and the distillate,when treated with iodine vapour, gave visible traces of mercuriciodide ; the same test applied to the lead electrode material gavenegative results.The earlier experiments with the quartz-lead lamp were neces-sarily of short duration, as the tubes were so blackened by a filmof lead silicate and silicon that observation became impossibleafter a few hours.A modified design of lamp now employed permitsmuch longer runs and the light after 39 hours shows a very strongmercury spectrum. In yet another experiment, 850 g. of leadremoved from a lamp after being used to produce an intermittentarc for 188 hours were heated to 800" in a quartz apparatus in acurrent of pure nitrogen, which then passed through two U-tubescooled in liquid air where 5 mg. of mercury condensed.Preciselysimilar treatment of the same quantity of the same sample of originallead which had not been used in a lamp gave no trace of mercury.These results are interpreted to indicate that a transmutation oflead into thallium and mercury has occurred, and whilst, of course,their general acceptance must await independent confirmation, theexperiments here referred to do seem to afford strong evidence oftransmutation.66Group V.The heat of formation of active nitrogen has been determined bycausing a current of activated gas to react with nitric oxide in acalorimeter and measuring the heat evolved and the amount of6 5 J. H. de Boer, 2. anorg. Chena., 1926,150, 210; A,, 373.66 A. Smits end A. Karssen, 2. Elelctrochem., 1926, 32, 578; A. Smita,Nature, 1926, 117, 13; A,, 106; compare idem, 2.anorg. Chew., 1926, 155,369; A,, 1016; (Miss) .4. C. Davies and F. Horton, Nature, 1926, 117, 152;A., 221; A. Smite., ibid., p. 620; A., 554.REF.-VOL. XXIII. 66 m& REPORTS ON THE PROQREBS OF CHEMISTRY.nitrogen peroxide produced. The mean value obtained for the heatof formation, 42,500 cal./g.-mol. (about 2-0 volts), supports thehypothesis that active nitrogen is nitrogen in a metastable molecularform. Observations of the effect of various gases in extinguishingthe fluorescence of active nitrogen indicate that only those for whichthe critical increments are less than a value approximately equal tothe above heat of formation have a positive effect.67 On the otherhand, the second positive group of bands, which predominates inthe discharge on activation of nitrogen, is believed to be due to theatom.68Nitrous oxide has been synthesised by passing an electric dis-charge through nitrogen a t a low pressure contained in a tube offused silica, the walls of which had previously been saturated withoxygen by passing a discharge through the tube lilled with thatgas.The nitrous oxide was isolated as i t was formed by condensingit in a U-tube surrounded with liquid air.60In the course of measurements of its compressibility up to 160atm. and over the temperature range -SO" to lo", it has been ob-served that under prolonged compression nitric oxide decomposes,yielding a blue, liquid mixture of nitrous oxide and nitrous anhydride.At 700 atm.the decomposition is very rapid. Freshly-preparedand liquefied nitric oxide is but faintly blue in colour, and the puresubstance would probably be colourless, but multiple liquefactiondoes not effect purification, since the intensity of the blue colouris thereby gradually increased.50 On the other hand, nitric oxideis formed in appreciable amounts (up to 25% of that required by theequation 2N,O + 2NO + N,) by dissociation of nitrous oxideat 1300". At lower temperatures (700"), the decomposition isslower and proceeds chiefly according to the exothermic reaction,2N,O + 2N, + 0, ; the former, slightly endothermic, reaction isfavoured by rise of ternperat~re.~~It has been found that the decomposition of nitrogen pentoxideis not accelerated by infra-red radiation corresponding with its strongabsorption bands ; this is contrary to the predictions of the radiationtheory.72 A study of the thermal decomposition of nitrogen pent-6 7 E.J. B. Willey and E. K. Rideal, J., 1926, 1804; A., 893; E. J. B.Willey, Nature, 1926, 117, 381; A., 336; ibid., 118, 735; A., 1213.M. Duffieux, ibid., 117, 302; A., 336; compare (Lord) Rayleigh, ibid.,p. 381; A., 336.D. L. Chapman, R. A. Goodman, and R. T. Shepherd, J., 1936, 1404;E. Briner, H. Biedermann, and A. Rothen, He2v. Chiin. Acta, 1935, 8,Aq 811.923; A., 1926, 16.'l E. Briner, C. Meiner, and A. Rothen, ibid., 1926, 9, 409; A., 686.72 H. A. Taylor, J . Amer. Chem. Soc., 1926, 48, 677; A., 485; compareF. Daniels, ibid., p. 607; A., 485INORGANIC CHEMISTRY.67oxide a t low pressures has shown that dissociation is not retardedby lowering of pressure, but below a critical pressure, approxim-ately 0.25 mm., it is gradually accelerated with falling pressure until,a t the lowest pressures, the rate of dissociation becomes approxim-ately constant a t about five times the normal value. This curiousobservation is quite irreconcilable with all '' chain " mechanisms,and is most readily interpreted on the assumption that a definitefraction of the activated molecules always undergoes decompositionirrespective of pressure, but that a larger fraction (about four-flfths)does not decompose if i t collides within 10-6 see. after activation,but is deactivated by collision. Calculations on this basis are ingood agreement with experiment.A possible explanation of thetwo different types of activated molecules is offered, based on thefact that there are four N-0 linkings, and only one shared N-0linking in the molecule of the pentoxide. Activation of one linkingcauses decomposition-activation of the shared linking invariablyso; activation of the others, only after a time interval and ifcollisions do not intervene.73A number of reactions of elements electronegative to nickelupon ammonio-bases in liquid ammonia solution have been investig-ated : the initial reaction is of the type C1, + 2KOH j KC1 +KClO + H,O. By the action of sodamide or potassamicle uponexcess of tin amalgam, new sodium and potassium ammoniostann-ites, Na (or K)[Sn(NH,)J, have been obtained.'* A break a t 310"in the decomposition curve of the compound PCl,,lONH, corre-sponds with a break observed a t the same temperature with amixture of ammonium chloride and sand, and thus suggests thatthe substance is partly a mixture of ammonium chloride and theamine P(NH,),-a view which is supported by the action of liquidammonia on the sul~stance.~~Pyridine hydrazinedisulphonate is prepared in S0-85% yieldby the action of chlorosulphonic acid on a, suspension of hydrazinesulphate in cold pyridine and subsequent precipitation of the saltby addition of ethyl alcohol ; the corresponding ammonium (+ H,O)and sodium (+ 2H,O) salts are described.The pyridine salt isoxidised by sodium hypochlorite in the presence of water a t -20"to the azo-compound, isolated by addition of potassium chloride aspotassium azodisulphonate, S0,K.N:N.S03K.70Red or yellow phosphorus reacts with water a t 238-360" and'3 H.S. Hirst and E. K. Rideal, Proc. Roy. Soc., 1925, [ A ] , 109, 626; A.,74 F. W. Bergstrom, 6. Physical Chem., 1926, 30, 12; A., 264.7 6 H. PerpBrot, Bull. SOC. ckim., 1925, [iv], '37, 1640; A., 1926, 137.76 E. Konrad and L. Pellens, Ber., 1926, 69, [B], 136; A., 370.1926, 3268 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.57-360 atm. to form phosphine and orthophosphoric acid thus :4P, + 12H20 + 3H,PO, + 5PH,. If hydrogen be added, theproportion of phosphine increases until, with dry hydrogen at 360"or less, it is the sole product. When phosphorus is heated withwater for a short time a t 248" and 48 atm.and the reaction is rapidlyinterrupted, there is formed a crystalline purple phosphorus, d 1.93,which has an ignition temperature 210". At higher temperatures,and pressures (360-380" and )90 atm.) crystalline black phos-phorus, d 3.06, is formed, apparently by decomposition of phosphinefirst formed.The velocity of air-blast required to remove the glow from phos-phorus and maintain it downstream may be used as a measure ofthe rate of propagation of the glow. Using this method in an exten-sion of Rayleigh's experiments, it has been found that inhibitors,such as ethylene, benzene, chloroform, and aniline, diminish the rateof propagation, and to an extent which is lessened by rise oftemperature, and thus act in this matter just as oxygen d0es.7~The addition of stannic chloride, either as solid or in very con-centrated solution, to a concentrated solution of sodium hypophos-phite produces a voluminous, white precipitate of a strongly reduc-ing substance, the analysis of which corresponds with the formulaSnCI,,Sn( H2P0,),,3H,0.When heated, the substance is dehydrateda t 140", and decomposes a t 190" with a characteristic reddeningand the evolution of phosphine. If the heating is stopped imme-diately the red colour appears, and the mass extracted with con-centrated hydrochloric acid, a bright red residue remains, whichhas very strong reducing properties and a composition approximat-ing closely to that of phosphorus suboxide, P40.79A large number of new complex metallic phosphites and pyro-phosphates have been prepared.soPhosphorus nitride, PN, has been obtained by passing a dischargebetween aluminium electrodes in nitrogen a t about 200 mm.in atube lined with yellow phosphorus, extracting the product withcarbon disulphide, and heating the residue in porcelain a t 550"in a stream of nitrogen a t 12 mm. pressure. The residual nitride isa voluminous, yellowish-brown powder, very resistant to chemicalagents .81The preparation of an acid barium vanadate, 2Ba0,3V20,,12H,O,7 7 V. Ipatiev and W. Nikolajev, Ber., 1926, 59, [B], 695; A,, 487.H. J. Emelhs, J., 1926, 1336; A., 777.A. Terni and C. Padovani. Atti R. Accad. Lincei, 1925, [vi], 2, 501; A.,A. Rosenheim, S.Frommer, H. Gliiser, and W. Hiindler, 2. anorg. Chem.,1926, 265.1926, 153, 126; A., 696.81 W. Moldenhauer and H. Dorsam, Ber., 1926, 59, [B], 926; A., 696INORGANIC CHEMISTRY. 69has been described ; and from this salt, by interaction with metallicsalts, similar vanadates of nickel, cobalt, copper, beryllium, cad-mium, and manganese are obtained. They take up gaseous ammoniaslowly, and combine more rapidly with liquid ammonia, to formhexammines.82Group V I .Excess of hydrogen sulphide acts upon 1% aqueous potassiumpermanganate according to the scheme 10KMn0, + 22H,S +3K,S04 + lOMnS + 2K,S,03 + 22H20 + 5s ; in the earlier stagesof the reaction some dithionate is formed.83 Experiments upon thedecomposition of dilute aqueous thiosulphuric acid have shown thatthe yellow colour characteristic of such solutions is due to a sulphurcompound derived from the oxide S,03; about 407; of the totalsulphur present exists in this formas4 In contirmation of this, it isfound that anhydrous thiosulphates with liquid sulphur dioxide a tlow temperatures yield yellow solid compounds, K,S,O,,SO, andRb,S,O,,SO,, which give clear yellow aqueous solutions in whichthe equilibrium S,O," + SO,The method of intensive drying has been applied to a furtherstudy of the complexity of the solid state; repeated distillationof the dried ice-like form of sulphur trioxide yields the high-melting(as distinct from the low-melting) asbestos-like form, and this givesmarked evidence of complexity by a great decrease of vapourpressure (from 591 to 37 mm.) on distillation.This low vapourpressure is substantially constant a t 18", but a t higher temperaturesit increases, approaching asymptotically the value corresponding toinner equilibrium. The establishment of equilibrium is hastenedby incidence of X-rays, and all forms yield identical X-ray photo-graphs. The original papers should be consulted for a full accountof the experimental method and of the argument directed toestablish the great complexity of the system formed by this simplecompound.86It is convenient here to mention other work of a kindred nature.To determine whether intensive drying results in a fixing of theinner equilibrium, or a displacement of the inner equilibriumfollowed by fixation, measurements of the vapour pressure ofintensively dried nitrogen tetroxide and m-hexane have been made.Nitrogen tetroxide, after intensive drying for 23 months a t the(S,O,(SO,)]" exists.858 3 F.Ephraim and G. Beck, Helv. Chim. Acta, 1926, 9, 35; A., 370.83 H. B. Duaaicliff and S. D. Nijhawan, J., 1926, 1; A., 256.84 E. H. Riesenfeld and E. Grimthal, Medd. K. Vetenskapsukud. NobeLInst.,O 5 F. Foerster and R. Vogel, Z . anorg. Chern., 1926, 155, 161; A., 1016.8 8 A. Smits and P. Schoenmaker, J . , 1926, 1108, 1603; A., 669, 785.1925, 6, No. 9, 1 ; A., 1926, 25770 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.ordinary temperature in an apparatus the glass of which was notfreed from capillaries, showed an increase in the vapour pressure of1.9 cm.of mercury; a part of the liquid was then distilled off, andthe increase fell to 0-4 cm., but after a further 11 days this hadrisen to 1.47 cm. In another apparatus made of capillary-free glass,a much more rapid drying effect was obtained, for after 16 monthsthe vapour pressure had risen by 3.3 cm. On raising the temper-ature, the increase passed through a maximum, as had been antici-pated on theoretical grounds. The changes of vapour pressure, andof colour to a deeper brownish-red, prove that the drying processhad effected a displacement of the inner equilibrium in the directionN,04 + 2N0,.With n-hexane, intensive drying a t about 40" results in a decreaseof vapour pressure. After only 14 weeks, this reached 0.9 om.,showing that, in contrast to nitrogen tetroxide, the iilner equilibriumis here shifted towards the less volatile component.The decreasewas augmented by raising the temperature, and after distilling offa portion of the liquid a t the drying temperature, the vapourpressure tended to revert to its previous value, showing that theinner equilibrium had not been reached.s7Pyrosulphuryl chloride has been prepared by the action of carbontetrachloride on sulphuric or chlorosulphonic acid a t SO", and is ahygroscopic substance, 1.834, n:"" 1,449, b. p. 57'130 mm.,52'115 mm., having a characteristic odour. When heated, it dis-sociates irreversibly according to the schemes S,O,Cl, --+ SO, +SO, + C1, and S,O,Cl, -+ SO, + SO,Cl,. Measurements of itsdiamagnetism and molecular refraction indicate the constitution :When chromium trioxide is heated a t 263") oxygen is evolved andthe liquid slowly solidifies to a dark brownish-violet mass of a newoxide CrsO1,, which, like the known oxide, Cr5012, appears to be achromate of chromium.89 The chromium carbonyl, Cr(CO),, hasbeen prepared by slowly adding ethereal magnesium phenyl bromideto an ether-benzene suspension of chromium chloride in presence ofcarbon monoxide belowSelenic-uranic acid, H,[U03(Se04)],2H,0, diselenic-uranic acid,H,[UO4(SeO4),],2H,O (and with 6H,O), and triselenic-diuranic acid,8 7 A.Smits, W. de Liefde, E. Swart, and A. Claassen, J . , 1926,2657; A.,1206; A. Smits, ibid., p. 2655; A., 1206; compare S. B. Mali, 2. anorg.Chem., 1925, 149, 150; A,, 1926, 117; J.W. Williams, J. Arne?. Chem. Soc.,1925, 47, 2644; A,, 1926, 15.88 V. Grignard and P. Muret, Compt. rend., 1926, 183, 581; A,, 1113;ibid., p. 713; A., 1218.s(:o)(ocl)*o~s(:o)(ocl).~~A. Simon and T. Schmidt, 2. anwg. Chem., 1926, 153, 191; A., 697.go A. Job and A. Cased, Compt. rend., 1926, 183, 392; A., 1017INORGANIC CHEMIETRY. 71H6[U02(U04)(Se04)3],7H,0, and a number of potassium andammonium salts derived therefrom, have been prepared.91By heating the known uranium nitride, U3N4, a t 1740" and 1900",two new nitrides, U,N4 and U,N,, are obtained : these differ fromU,N, in being completely soluble in acids with the evolution ofhydrogen and conversion of the nitrogen into ammonium salts.92Group V I I .Several oxidising reactions of fluorine have been investigated.Fluorine with aqueous ammonium hydrogen sulphate or drypotassium hydrogen sulphate yields considerable amounts of thepersulphates, in the latter case accompanied by potassium fluoro.sulphonate, KFS03.gSHydrogenchloride is found to combine readily with certain metallicsulphates, forming compounds of the type XS04,2HC1 ; this occurschiefly in the cases where the metallic chlorides do not readily yieldhydrogen chloride when treated with concentrated sulphuric acid,and the temperature a t which the evolution of gas begins is approxim-ately the dissociation temperature of the complex.94 Determinationshave been made of the vapour pressure of pure chlorine dioxide fromthe f .p. -59" t o the b.p. +l1°.95In an interesting investigation of the influence of water on theunion of halogens with hydrogen, it has been observed that whilstthe combination of hydrogen and iodine can be inhibited by inten-sive drying, the decomposition of hydrogen iodide, similarly driedand a t the same temperature, proceeds apparently unhindered.Hence, in this case, as in those previously mentioned, intensive dry-ing skifts the position of equilibriumag6Iodic acid and stannic chloride in dilute nitric acid solution yield,according to the conditions, dihydroxytetraiodatostannic acid,Sn(IO,),(OH),H,, or stanni-iodic acid, Sn(I03),H2. The alkali-metal salts of the latter acid and also of tetrahydroxydi-iodato-stannic acid, Sn(103)2(0H)4H2, have been prepared.Iodic acid andantimony pentachloride yield trihydroxytri-iodatoantimonic acid,Sb(I03)3(OH)3H.9791 J. Meyer and E. Kasper, 2. anorg. Chem., 1926, 155, 49; A., 926.92 0. Heuder, ibid., 154, 363; A., 909.98 F. Fichter and K. Humpert, Helv. Chim. Acta, 1926, 0, 467, 602, 692;a* F. Ephraim, Ber., 1925, 58, [B], 2262; A,, 1926, 36; itid., 59, [B], 790;95 F. E. King and J. R. Partington, J., 1926, 625; A.. 569.98 B. Lewis and E. I<. Rideal, J . Anzev. Chena. Soc., 1926, 48, 2553; A,,$ 7 P. R$y and S. N. Ray, J. Indian Chem. Soc., 1926, 3, 110; A,, 1015.A., 699, 925.A,, 587.111172 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.Although a good deal of discussion has taken place upon thesupposed discovery of dvi-manganese previously reported, nothingsubstantial has been added to our knowledge of the element.gBGroup V I I I .New hydrides of cobalt, iron, and chromium have been obtainedby the interaction of the chlorides of those metals with hydrogenin presence of magnesium phenyl bromide.Cobalt hydride has theformula CoH,; iron dihydride, FeH,, is a black powder; ironhexahydride, FeH,, is a black, viscous oil; chromium trihydride,CrH,, is a black p r e ~ i p i t a t e . ~ ~A study of the composition of various ferro- and ferri-cyanides,prepared in a variety of ways, has led to the conclusion that ordinaryPrussian blue is the ferrous salt of a complex acid formulated asThe identity of the absorption spectra of ferronitricoxide salts inaqueous solution confirms the view that they all give the samecoloured cation, FeNO' : and the similarity between these spectraand those of the black series of Roussin's salts lends support to theview that the latter should be formulated 2A number of interesting papers on complex cobalt salts cannotbe summarieed in the space available and must be dismissed with areference ?Platinum tribromide is obtained by heating platinum tetrabromidebetween 370" and 405" ; above 410°, the tribromide loses bromineto form the dibromide, but this is stable over a range of only 5'.J.Heyrovsk9, Nature, 1926, 117, 16; A,, 138; J. G. F. Druce, ibid.,p. 16; A., 138; V. Dolejitek, J. G. F. Druoe, and J. Heyrovsky, ibid., p. 159;A., 227; V. Dolejgek and J. Heyrovskf, Chem. Listy, 1926, 20, 4 ; A,, 258;F.H. Loring, Chem. News, 1926, 152, 101; A., 338; 0. Zvjaginstsev, M.Korsunski, and N. Seljakov, Nature, 1926, 118, 262; A., 934; B. Polland,Con~pt. rend., 1926, 183, 737; A., 1194; F. H. Loring and J. G. F. Druce,Chem. News, 1925, 131, 337; A., 12.Q Q T. Weiohselfelder and €3. Thiede, Annulen, 1926, 447, 64; A., 372.N. Tamgi, Cfazzetta, 1925, 55, 951; A., 1926, 259.W. Manchot and E. Linckh, Ber., 1926, 59, [B], 406, 412; A., 452, 453.E. H. Riesenfeld (with W. Petrich), iMedd. K . Vetenskapsakad. Nobel-Inst., 1925, 6, No. 6, 1 ; A., 1926, 259; R. Klement, 2. anorg. Chem., 1926,150, 117; A., 372; F. L. Hahn, H. A. Meier, and H. Siegert, ibid., p. 126;A., 372 ; F. M. Jaeger and P. Koets, Proc. K. Akad. Wetensch. Amsterdam, 1926,29, 5 9 ; A., 697; J. Meyer and K. Grohler, 2. anorg. Chem., 1926, 155, 91;A., 925; B. K. Paul and P. V. Sarkar, A m . Chim., 1926, [XI, 5, 199; A., 588INORGANIC CHEJIISTRY. 73Platinum tetraiodide is produced by heating platinum with iodinein a sealed tube a t 240-300", and this is converted to the tri-iodidea t 350400°.4Tensimetric determinations of the molecular weights of cis- andtrans-dichlorodiamminoplatinum in liquid ammonia show that thecis-salt has a normal and the trans-salt a double molecular weight.The latter salt is therefore formulated :The action of hydrogen peroxide or ozone on complex compoundsof bivalent platinum renders the platinum quadrivalent and therebyadds two negative groups to it. Thus, from Peyronne's chloride areobtained the dihydroxy-compound, [Pt,SNH,,Cl,(OH),], and a newhydroxypentamminoplatinic carbonate, [Pt,5NH,,0H],(C03),.gBy passing carbon monoxide into a suspension of palladouschloride in anhydrous alcohol at 0", or by passing the gas, chargedwith methyl alcohol vapour, over palladous chloride a t 15", the com-pound PdCl,,CO is obtained. It readily decomposes into palladiumand carbon dioxide.7Ruthenium tetrachloride, RuC1,,5H20, has been obtained ashygroscopic, reddish-brown, monoclinic crystals. It is formed whena solution of hydroxytetrachlororuthenic acid in concentratedhydrochloric acid is saturated with chlorine for 5 hours a t 100" andthen evaporated in a current of dry chlorine. It is hydrolysed indilute solution, but in a strong solution is stable a t 15", does notliberate iodine from potassium iodide, gives a black precipitate withsilver nitrate and forms crystalline double salts with potassium andammonium chlorides.*Two new chlorides of rhodium, RhCl and Rha,, result from theaction of chlorine on rhodium a t 948-96gb; and by dissociationof rhodium trioxide a t 750" in oxygen, two new oxides, Rh,O andRho, insoluble in acids, but readily reducible by hydrogen, havebeen ~ b t a i n e d . ~H. V. A. BRISOOE.L. Wohler and F. Miiller, 2. anwg. Chem., 1925, 149, 377; A., 1926, 259.H. Reihlen and K. T. Nestle, Annalen, 1926, 447, 211; A., 699.L. Tschugaev and W. Chlopin (with E. Fritzmann), 2. anwg. C?bem.,' W. Manchot and J. Konig, Ber., 1926, 50, [B], 883; A,, 698; compare1926, 151, 253; A., 373.W. Manchot, ibid., 1925, 58, [B], 4518; A., 1926, 138.S. Aoyama, 2. anorg. Chem., 1926, 153, 246; A., 698.L. Wohler and W. Muller, ibid., 1925, 149, 125; A,, 1926, 138.C

ISSN:0365-6217    

DOI:10.1039/AR9262300049

出版商:RSC    

年代:1926

数据来源: RSC

摘要:

ORGANIC CHEMISTRY,PART I.--~PHATIO DMSION.C a r b o h y d r a t e s .Oxide-Ring Structure in the Sugar Group.The traditional formulae for a- and p-glucose (I and 11) and fora- and p-methylglucoside (I11 and IV) have been accepted withoutserious question and in the absence of rigid proof during severaldecades. Fischer’s choice of a five-membered ring to representthe cyclic system in glucosides and disaccharides established a modeof formulation which has been generally accepted for 40 years.The same cyclic structure has been applied to the free sugars them-selves, in view of their existence in two stereochemical forms quiteapart from the usual d- and I-enentiomorphs.first showed the structural relationships of a- and p-glucoses to u- andB-methylglucosides, and this experimental proof carries convictionindependently of the precise oxide-ring structure which may beapplied to these substances.E. F.Armstrongr- r- r--(1.1 (11.1 (111.) PV.1A criticism of the validity of Fischer’s statexent as to the struc-tural identity of 05- and p-methylglucosides was contributed byNef 2 in 1914. The latter author discovered a second crystallinegluconolactone which he described as a $-lactone, isomeric with t,hey-gluconolactone already known, He deduced from this resultthat the two lactones should correspond with two structurallydifferent types of glucoses or methylglucosides, and as only twosuch forms were known he advanced the opinion that a- andp-methylglucosides contained different oxide rings, one being abutylene oxide and the other a propylene oxide.J ., 1903, 83, 1306. 2 Annalen, 1914, 403, 204ORC3AMC CHEMISTRY.-PART I. 75Fischer’s reply 3 is noteworthy not merely since it confirmed theessential stereochemical relationships as opposed to the structuralisomerism of the glucosides suggested by Nef, but because in thesame paper he announced the discovery of a new variety of methyl-glucoside which he designated the y-form. This was structurallydifferent from either of the previously known forms, and wasprepared by condensing glucose with methyl alcohol a t a lowertemperature. The idea that this new glucoside might be correlatedwith Nef’s second lactone was not developed, but the occasion isinteresting hietorically since the comparative study of derivativesof y-sugars alongside those of the normal sugars has latterlyfurnished the initial data for the revision of the structural formulaewhich has now been proposed.A scrutiny of the evidence for the butylene-oxide formulaascribed to glucose and the normal glucosides reveals little morethan an assumed analogy of their ring structure with that of they-lactones to which sugars most readily give rise on oxidation.Inasmuch as the “ lactol I’ ring of a sugar is not preserved duringoxidation to the lactone, the latter being formed through theintermediate stage of the open-chain acid, the supposed identityof the cyclic forms of lactone and sugar is seen to depend on anassumed similarity of tendency of open chains, whether they bealdoses or polyhydroxy-acids, to undergo the same type of ringclosure.Although there are grounds for this expectation as betweenaldoses and ketoses, yet there is less immediate reason for anticipat-ing the same consistency in type, character, or stability of ringforms as between, say, hexoses and their carboxylic acids.This problem has been studied4 from the standpoint of thelactones derived from simple methylated sugars, and in a series ofpapers a comparison has been made of those lactones obtainedfrom methylated hexoses and pentoses of the normal or usual typewith others which were derived from the methylated y-sugars.The two series of lactones differed widely in their properties, but i twas found that sugars giving lactones of one structural type couldbe so transposed as to give lactones of the second type.A simplifiedexample of this inter-relationship as applied to glucose is as follows :A partly substituted glucose was selected, having substituentmethyl groups in the 2 : 3 : 6-positions, and, although this is knownto possess an oxide-ring structure, it is preferable a t this stage toBer., 1914, 47, 1980.W. N. Haworth, Nature, 1925,118, 430; W. Charlton, W. N. Haworth,end S. Peat, J . , 1926, 89; A., 273; W. N. Haworth end G. C. westgerth,ibid., p. 880; A., 600; W. N. Haworth and V. S. Nioholson, Bid., p. 1899;A., 102576 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.represent this 2 : 3 : 6-trimethyl glucose provisionally by the aldoseformula (V) in order to avoid any anticipation of the issue of theargument.Clearly the oxide ring can only be in either position1 : 4 or 1 : 5. On oxidation, the sugar (V) gives the 2 : 3 : 6-tri-methyl gluconic acid (VI), and this passes easily and almost com-pletely into the lactone (VII) which, on the basis of Hudson’s lactonerule,5 is identified as a y-lactone, Le., having the ring in position1 : 4. Methylation of the exposed hydroxyl group leads to thefully methylated 2 : 3 : 5 : 6-tetramethyl gluconolactone (VIII),which has latterly6 been obtained as a crystalline solid. Thisyields the crystalline phenylhydrazide of the corresponding acid.The same lactone is also obtained on oxidising the tetramethyly-glucose derived from the methylation of Fischer’s y-methyl-glucoside, and therefore the structure of tetramethyl y-glucose isrepresented by formula (IX), and Bischer’s y-methylglucoside thuscontains a butylene-oxide ring.(1) q H 0(2) H*v-OMe(3) Me0-V-H(4) H-Y*OH(V.1r-$!O*OHH*(j.OMeMeO4j.H 0H*V*OH --3HOOH&,.OMeWI.)YO---H*y.OMeCH,.OMeOX.) (VIII.) (X.)6 J.Amer. Chem. SOC., 1910, 32, 338.6 W. N. Haworth and S. Pest, J . , 1926, 3094ORGANIC CHEMISTRY .-PART I. 77Reverting now to 2 : 3 : 6-trimethyl glucose (formula V), thissugar passes on methylation to the normal crystalline tetramethylglucose, which on oxidation yields a liquid tetramethyl glucono-lactone differing markedly in properties from the above 2 : 3 : 5 : 6-tetramethyl lactone, and gives rise to a different crystalline phenyl-hydrazide.This liquid lactone can only be a 6- or 1 : 5-lactone (X),since this is the only alternative available, inasmuch as the remainingpositions are occupied by methyl groups. This definitely fixes theconstitution of normal crystalline tetramethyl glucose as an amyleneoxide (XI).A second and independent line of argument is based on a com-parison.of the chemical behaviour of the two series of lactonesobtainable from the normal and from the y-derivatives of glucose,galactose, arabinose, and xylose. The two series of lactones differedessentially both in the rate and in the extent of their hydrolysisin water, as determined by polarimetric data, and, partly, bytitration. Those derived from the methylated y-sugars hydrolysedslowly and very incompletely ; those from the normal methylatedsugars hydrolysed rapidly and much more completely, and theseresults are expressed graphically by the authors in a series of curves.Now y-galactonolactone and y-arabonolactone give on methylationthe same products respectively as those obtained by direct oxidationof tetramethyl '' y "-galactose and trimethyl '' y "-arabinose andtherefore the fortuitous use of the term ' ( y "- in the latter nomen-clature happens by coincidence t o acquire a structural meaning,and these sugars are 1 : 4- or butylene oxides.On the other hand,the tetramethyl galactonolactone derived from normal tetramethylgalactose has already been shown to be an amylene oxide. Similarly,the normal forms of trimethyl arabinose and trimethyl xylose areknown to be amylene oxides and thus give 6- or 1 : 5-lactones, sincethey pass on oxidation to trimethoxyglutaric acids.To summarise: Of the four sugars examined, three givemethylated " y "-derivatives which are true butylene oxides.Thesame three also give methylated normal derivatives which areamylene oxides, leaving only the two methylated glucoses to beallocated. Now the properties of the lactone obtained fromcrystalline tetramethyl glucose (prepared from u- or @-methyI-glucoside) are almost indistinguishable from those of the amyleneoxide or %lactones from methylated normal galactose and arabinose,and thus by analogy the normal crystalline tetramethyl glucoseis given the amylene-oxide structure, thus confirming the resultalready reached from the first line of reasoning.The difference in the properties of lactones of the two types isagain illustrated by the work of P.A. Levene and H. S. Simms,'J. Bwl. Chem., 1926, 68, 737; A., 102578 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.who have confirmed the presence of five- and six-membered ringsin methylated sugars of different origin.A third line of argument has also been presented, furnishing afinal confirmatory proof. Crystalline tetramethyl glucose (XII) wasoxidised 8 with nitric acid and xylotrimethoxyglutaric acid (XIII)was isolated, and consequently by these independent lines of investig-ation the amylene-oxide structure of u- and p-methylglucosidesand crystalline tetramethyl glucose is indicated, and by inferencethe same structure is applied to free glucose.{ H X l IH.‘.OM0Ha ’*OMe 1CH,-OMe(XII.) .H (XIII.)H. . I L: -Methylation of rhamnose under a variety of conditions furnishesa normal trimethyl methylrhamnoside of definite structural form.Oxidation of this with nitric acid gives a quantitative yield ofZ-arabotrimethoxyglutaric acid, CO,H.[CH~OMe],*CO,H, and thisresult can only be interpreted on the basis of the amylene-oxidestructure for this methylated sugar. From a comparison of thestereochemical forms of rhamnose, i t is suggested,lO however, thatone of these forms is not a normal variety of the sugar and containsa different ring structure, and a similar view is held with regard toone of the stereochemical forms of mannose.Contrary conclusions as to the structure of methylglucosides arereached, however, by Hudson,ll who has instituted R comparison ofthe rotatory relationships of the methylglucosides with those of themethylarabinosides, xylosides, and galactosides.The argumentsadvanced by this author favour the old formula for the a- andp-methylglucosides. Replying to this criticism, Drew and Haworth l2question the validity of conclusions based on a comparison of themagnitude of rotatory values displayed by optically active systemsso dissimilar as the methylglucosides and arabinosides, since thering-forming oxygen joins in the first case two asymmetric atomsdirectly and in the second case only one such atom. AcceptingHudson’s lactone rule as true, namely, that the rotation sign tends8 E.L. Hirst, J., 1926, 360; A., 386.8 E. L. Hiret and A. K. Macbeth, ibid., p. 22; A., 273.10 C. S. Hudson, J. Amer. Chem. Soc., 1926, 48, 1427; A., 714.11 Ibid., p. 1434; A., 714.11 J., 1926, 2303; -A., 1126ORGANIC! CHEMISTRY.-PART I. 79to be in the positive sense when the lactone ring formation engagesa hydroxyl group on the right of Fischer’s projection formula,and, conversely, tends to be negative when a hydroxyl group onthe left is engaged in ring formation, then it is argued that aparallel significance should be attached t o the spatial placing ofthe ring to the right or the left in the free sugars or their glucosides.This possible extension of Hudson’s lactone rule to the sugarsproposed by Drew and Haworth can only be tested if the rotatoryeffect of the reducing group can be eliminated as is the case in thelactones themselves.This can be achieved in those cases where thecrystalline u- and p- forms of sugars are already known, since themean of the specific rotations of these two forms of the same sugargives the rotatory effect of the remaining carbon atoms. Thus, ifthe rotation effect of the reducing carbon in the a- and p-modific-ations be expressed by + A and --A respectively, and all theremaining carbon atoms in the sugar chain be considered as havinga rotation + B , then the rotation of the a-variety is expressed by + A + B, and similarly that of the p-variety by - A + B. Thesum of these values, halved, gives the rotation effect of B.Proceeding in this way i t is shown that where the amylene-oxidering would engage a hydroxyl group on the right of the projectionformula the equimolecular mixture of K- and p- forms has a positiverotation, and in the converse case the sign is negative.Thereappear to be few, if any, exceptions to this rule when authenticdata are available, but two cases, mannose and rhamnose, me ex-cluded, since for other reasons the u- and p- forms are consideredto be abnormally related. Non-crystalline sugars are clearlyexcluded from the scope of this survey, as also, but on differentgrounds, are the simple pentoses, since the amylene-oxide ring in,e.g., xylose and arabinose joins the two terminal carbon atoms, oneof which is not asymmetric.Except in the simple pentosos, ringclosure is effected by exercising rotational movement round thecarbon intermediately situated in the chain, the effect of which isto bring the atoms constituting the ring into one central plane,with its addenda laterally extended. Thus the aldose form ofglucose (XIV) changes to the amylene oxide form by the inversionof the groups round C(5), as in (XV)80 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.This generalisation is markedly displayed in the case of thosemonoses prepared by Fischer by ascending the sugar series from thehexoses to the octoses. Thus, whilst the lactone rule holds ifthe butylene oxide ring is applied to those higher lactones whichare intermediate stages in the ascent of the sugars, the adoption ofa similar rule breaks down if the derived sugars are regarded asbutylene oxides, but holds in all authentic cases if the sugar isconsidered as amylene-oxidic. For example, the equimolecularmixture of the two glucoheptoses has a positive rotation when thering engages the hydroxyl group a t carbon atom 4 of the glucosechain, but when gluco-octose is reached the rotation is negative,and in this case the hydroxy1 group on C(3) is directed t o the left.The normal aldoses having been said to conform to the generaltype of amylene oxides, the characteristic ketose, fructose, is nowshown to fall within the same generalisation. The lsvorotatoryfructose, or Isvulose, gives on methylation a crystalline tetramethylfructose which is similarly lsvorotatory.By oxidation with nitricacid, this sugar is degraded to arabotrimethoxyglutaric acid (XVII)and dimethyl mesotartaric acid (XVIII), both products beingrecognised as the crystalline amides.13 The amylene-oxide formula(XVI) is therefore ascribed to tetramethyl fructose, and presumablyalso to free fructose. Accompanying these products of oxidationis a crystalline ester to which is given the provisional formula (XIX).It is probable that the degradation product described by previousQH20Me .....................yo&Me0y.HH.y.OMeH. '-0Me&O,H(XVI.) (XVII.)18 W. N. Heworth and E. L. Hirst,press, Bid., p. 1720; A,, 942.H O . r E 1p 2 H Me0.y.HH+'.OMe H*v-OMeH*y.OMe H O O M ~CO,H 4H2(XVIII.) (XIX.)J., 1926, 1868; A,, 1126; C.F. AllORGANIC CHEMISTRY.-PART I, 81authors as the diethyl ester of dimethoxyhydroxyglutaric acid isthe monoethyl ester corresponding to (XIX), and accordingly thisearlier claim 14 to have established the butylene-oxide structure ofnormal fructose is disputed.If this dethronement of the older fructose formula from itsposition in the ketose series be accepted, the implications are asimportant as those resulting from the revision of the older glucoseformula in the series of the aldoses. In the same paper describingthe experimental proof of the new structural formula of fructose,Kaworth and Hirst have also revised the constitution previouslyassigned to tetramethyl y-fructose, the dextrorotatory sugar isolatedfrom methylated sucrose, raffinose, and inulin.These authorspropose the butylene-oxide formula for derivatives of y-fructoseon the analogy of the structure already assigned by one of them tothe y-aldoses. Against this view, G. McOwan l5 has revived thepropylene-oxide formula for tetramethyl y-fructose, and has adducedevidence, largely critical of earlier work, in support of his proposal.It is suggested that the primary product isolated by oxidation oftetramethyl y-fructose with nitric acid is not a trimethoxyvalero-lactone, but a keto-ester (A) or (B), whence i t is argued that theoriginal sugar is a propylene oxide as represented by (C). Theketo-ester (A) or (B) is not definitely characterised, and it wouldseem that the isolation of a product (A) would equally well satisfythe requirements of a butylene-oxide structure.FH,*OMeyH,*OMe ,-Y*OH FO*OMeYO OYH-OMe - YO‘H*OMe LYH yH.OMeZo*oMe UH-OMe CH,*OMe(4 (C) (B)Whilst the arguments already outlined may be said to have estab-lished the amylene-oxide structure of the representative referencecompounds, a- and p-methylglucosides, crystalline tetramethylglucose, etc., it is urged by several authors l6 that the unsubstitutedglucose has not necessarily the same oxide ring.Doubt is thus caston the inter-relationship of E- and p-glucoses with a- and p-methyl-glucosides, which was considered to have been firmly establishedby E. F. Armstrong. The reason advanced for this uncertainty isthe existence of glucose diacetone, which has been shown to have thebH,.OMe14 J.C. Irvine end J. Patterson, J . , 1922, 121, 2696.1; J . , 1926, 1742; A., 941.K. Freudenberg and K. Smeykel, B e y . , 1926, 58, 100; A., 274; P. A.Levene and H. S. Simms, J . Bid. Chem., 1926, 68, 737; A., 102582 ANNUAL REPORTS ON TEE PROGRESS OB CHEMISTRY.butylene-oxide structure (D),17 since it gives, after methylation andelimination of the acetone residues, 3-methyl glucose. The latterrtugar yields the same osazone as the monomethyl fructose derivedfrom a-fructose diacetone, which has therefore the constitution (E).I- 1 I IYH,.OH(D) (E) (F)The isomeric p-fructose diacetone is assigned the constitution (F),which differs structurally from that of the a-isomeride, and notmerely stereochemically.Now, as glucose passes 80 readily into the compound (D) bysimple condensation with acetone, the inference is drawn that thebutylene-oxide ring in the diacetone derivative may have beenpre-formed in the original glucose, which in such case would retainits old position as a butylene-oxide sugar despite the amylene-oxidestructures of a- and p-methyIglucoside and crystalline tetramethylglucose. This hypothesis receives some support l9 from,the analogyof the diacetone derivative of mannose, to which is allocated also abutylene-oxide structure (G).qH*OH r-1 10-p-H 0cMeZ<O.F.H 1H'FHmgGE>CMez(GI (HIOn the other hand, to galactose diacetone the constitution (H) isdefinitely assigned.,OFrom a consideration solely of the oxide-ring structures of thediacetones it is suggested that, whilst fructose and galactose possessamylene-oxide rings, mannose and glucose, on the other hand,'7 J.C. Irvine and J. Patterson, J., 1922, 121, 2146.I * H. Ohle, I. Koller, and G. Berend, Ber., 1925, 58, 2575; A., 1926, 150.18 H. Ohle and G. Berend, ibid., p. 2560; A., 1926, 150; X. Freudenbergand A. Wolf, ibid., 1926, 59, 836; A., 601; J. C. Irvine and A. F. Skinner,J., 1926, 1089; A., 714.10 15. Freudenberg and K. Smeykal, Be?., 1926, 59, 100; A., 274ORGANIC CHEMISTRY .-PART I. 83contain the butylene-oxide rings, This argument is only validif i t be assumed that the ring systems of the parent sugars remainunimpaired by the entry of acetone groups in the adjoining hydroxylpositions.There is, however, much reason to doubt the accuracyof this assumption.21 It appears to be the accepted rule thatacetone, like boric acid, condenses with cis-hydroxyl groups inadjoining carbon atoms in cyclic systems,22 and unless thisprinciple is abrogated, the structure of xylose diacetone shouldbe (J), which is seen to present yet another type of sugar ring-ar-i ), VH">CMe22 H-7-0rYH">CMeH*Y-OL--p 1 H O - ~ HH*F-o>me, ----OHCH,. 0 "*b-O>CMe, CH2* 0(J) (K)propylene oxide-which would be the first authentic case of theexistence of a sugar derivative in a third structural form, sincetwo varieties, the normal and the y-form of xylose, are also known.If this should prove to be the case, or alternatively, if the secondform of a galactose diacetone (K) should be isolated differing from(H) in having a butylene-oxide ring, then the truth with regardto the formation of acetone derivatives of sugars will be thatacetone condenses with appropriately situated hydroxyl groups inany sugar regardless of any pre-formed sugar ring.The ringsystem in the parent sugar will then have been shown to adjustitself to that position left open after the entry of acetone residuesby a process of preferential selection. A reason would thus beprovided for bhe existence of acetone-sugars containing rings of avariety of types, formed quite irrespectively of the original ringsystem in the parent free sugar. The shift in the position of attach-ment of the oxide ring in glucose during its condensation with acetonewould, indeed, correspond with that which is known to occur, forexample, when amylene-oxidic galactose condenses a t room temper-ature with methyl alcohol to give a butylene-oxidic y-methylgalactoside.Monosaccharides.From the point of view of the possible synthesis of a-glucosides,the preparation 23 of p-chloro-3 : 4 : 6-triacetyl-2-trichloroacetyl-al H.Ohle and I<. Spenoker, Ber., 1926, 59, 1836; A., 1126.22 J. BBeseken and Mlle. A. Julius, Rec. trav. ckim., 1926, 45, 489; A,*3 P. Brig1 and H. Keppler, Ber., 1926, 59, 158s; A., 941.818. Compare also earlier work84 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.glucose is of importance, since this readily gives rise to a-methyl-glucoside on boiling with methyl alcohol in presence of silvercarbonate. The better-known halogen derivative, a-bromotetra-acetylglucose (tetra-acetyl-glucosidyl bromide), yields onlyp-glucosides under similar conditions. In this connexion, theisolation of p-chlorotetra-acetylglucose 24 as a pure crystallinecompound is of significance, but the preparation of this reagentrequires the application of most stringent conditions.The prepar-ation of a stable form of glucose25 is reported which is said tocontain a different ring structure from either the normal or theusual y-type. Derivatives of this variety have been isolated as apenta-acetate and a trimethyl sugar xvhich are said to possessconsiderable stability of grouping and to contain a hexylene-oxidering.A new aminohexose,Z6 containing the amino-group in position 3and therefore differing structurally from glucosamine, has beenprepared from glucose diacetone, whilst 3-chloro-glucose 27 alsohas been obtained from the same source by the agency of phos-phorus pentachloride and sodium carbonate, a method whichpays tribute to the remarkable stability of the combined acetoneresidues in glucose diacetone.A study of the conditionsz8 ofentry of substituted groups into glucose monoacetone is also con-tributed, showing that position 6 is first attacked by reagents, andif this is already substituted, then position 5 is preferred, since theoxide ring in this acetone compound engages the positions 1 : 4.In continuation of previous work on the preparation of sugarcarbonates, a series of five derivatives of arabinose and xylosecontaining carbomethoxy- and carbethoxy-groups is reported.29Improved experimental conditions for the preparation of thesimple oxidation products of sugars are described.30 These includeI-arabonic, I-mannonic, and I-gluconic acids and the related lactones.The extension of this work t o the '' uronic " acids will be welcomedin view of the study of the structure of the pectins.The supposedsemicarbazones of gaIacturonolactone and mannuronolactone arenow shown to be semicarbazides of the unoxidised acids. A synthesisof sarcosine glucoside is described,31 and the action of carbamide2L H. H. Schlubach, ibid., p. 840; A., 600.2 5 H. Pringsheim and S. Kolodny, %bid., p. 1135; A, 822.z 8 I<.Freudenberg, 0. Burkhart, and E. Braun, ibzd., p. 714; A., 601.*' J. B. Allison and R. 31. Hiron, J. Arner. Ckenz. SOC., 1926, 48, 406; A,,386.H. Ohle and E. Diclrhiiuser, Ber., 1925, 58, 2593; A., 1926, 161.p8 W. N. Haworth and W. Maw, J., 1926, 1751; A., 940.30 H. Kiliani, Ber., 1925, 58, 2344; 1026, 59, 1469; A., 1926, 51, 940.31 K. JIaurer, i b ~ d . , 1926, 69, 827; A., 602ORGANIC CHEMISTRY .-PART I. 85on glucose, fructose, and mannose has been carefully studied,leading to an improved method of preparing gluco~eureide.~~Modified conditions for the preparation of hexoseanilides are alsoreported.%A series of interesting sugar nitrates 34 which are crystalline hasbeen prepared from glucosan, comprising 2 : 3 : 4-trimethyl glucose1 : 6-dinitrate, which can be converted into the corresponding2 : 3 : 4-trimethyl methylglucoside 6-mononitrate ; also the corre-sponding triacetyl glucose dinitrate and tetra-acetyl glucose mono-nitrate, the latter giving a tetra-acetyl glucose on hydrolysis.Other crystalline compounds of great interest are triacetyl methyl-glucoside 6-mononitrate, which hydrolyses to the triacetyl methyl-glucoside, and triacetyl methylglucoside-6-isohydrin.The occurrence of a thio-sugar in the adenine nucleoside fromyeast is reported.This sugar also contains a methyl group andappears to be a derivative of a k e t ~ s e . ~ ~Methylation of diethylmercaptoglucose, first by methyl sulphateand then by Freudenberg’s method, yields the completely methyl-ated derivative, and treatment of this with mercuric chloride leadsto the isolation of pentamethyl glucose.36 This is noteworthy asthe first example of the preparation of a true sugar-aldehyde.Thebehaviour of the latter with methyl alcohol is of marked interestin that it passes to the dimethylacetal with excessive ease. Theseproperties illustrate the difference between a heterocyclic-ring typeof sugar of the usual kind and the simplest open-chain type, and itis to be hoped that the study of this unique sugar compound will bepursued.3lzitarotation and Classi$cation.Lowry has continued his classical studies in dynamic isomerismand has measured the velocity of mutarotation of tetramethylglucose and of tetra-acetyl glucose in aqueous acetone. Thesignificant result emerges that acetone diminishes the catalyticactivity of water.37 Thus in a 5074 mixture of water and acetonethe velocity of mutarotation of tetramethyl glucose is about 20%of that in pure water.The catalytic activity of the water is notin proportion to its total concentration and is not a simple linear32 A. Hynd, Biochem. J., 1926, 20, 198; A., S o l ; B. Holferich and W.Kosche, Ber., 1926, 59, 69; A,, 273.ss C. N. Cameron, J. Amel.. Chem. SOC., 1926, 48, 2233, 2737; A., 1026,1228.J. W. H. Oldham, J., 1925, 127, 2940; A,, 1926, 151.P. A. Levene and G . M. Meyer. ibid., 1926, 69, 176; A., 1026.G . G . Jones and T. M. Lowry, J., 1926, 720; A., 491.s6 P. A. Levene and H. Sobotka, J. BioE. Chem., 1925,6S, 551 ; A., 1926, 6286 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.function of its activity as measured by its partial vapour pressureabove the solution.A maximum velocity of mutarotation for glucose, twenty timesthat shown in pure water, is attained by using a mixture of pyridinewith twice its weight of water as In the absence of water,pyridine and also cresol have by themselves no appreciable catalyticproperties, but a dry mixture of two parts of cresol and one part ofpyridine is twenty times more active than is water in promotingthe mutarotation of tetramethyl glucose.This increased activityis attributed to the amphoteric character of the mixed solvent, andthe conclusion is reached that to promote a change in position of anatom within the sugar molecule it is necessary to supply a mediuminto which a proton can escape and from which a proton can beprovided.This hypothesis is supported by the observation that theonly substances known to act as catalysts for the mutarotation ofsugars possess either acidic or basic properties, or both. Ethylacetate or acetone fails to accelerate this change even in presence ofwater, and in the dry condition these solvents and also pyridine arequite inert.Alcohols can be regarded as amphoteric in the sense that theycan liberate either hydrogen or hydroxyl to suitable chemicalreagents, although they do not necessarily possess susciently strongacidic and basic properties to react as complete catalysts for themutarotation of sugars. On this assumption a series of experimentshas been conducted with the use of the purest methyl alcohol.Itwas recorded 39 that methyl alcohol, mixed with three times its weightof cresol, gave a maximum coefficient which was ten times that ofmethyl alcohol alone, and further, that methyl alcohol mixed withtwo-thirds its weight of pyridine gave a value twenty times asgreat as the former mixture. It is concluded that since methylalcohol is sufficiently acidic to form a complete catalyst withpyridine, and sufficiently basic to form a complete catalyst withcresol, it must also be able to function alone as an amphotericsolvent to promote mutarotation of sugars. The velocity in ethylalcohol is eighty times less than the velocity in water. Otherexperiments show that neutral salts largely affect the speed ofmutarotation of a- and p-glucose, which display their minimumstability a t about the same pH value.It does not follow, however,that the dissociation constants of the sugars correspond. Appar-ently there is no evidence for the existence of a third undissociatedintermediate form, a conclusion which is of value in considering the38 T. M. Lowry and I. J. Feulkner, J., 1925, 127, 2883; A,, 1926, 148.as I. J. Faulkner end T. M. Lowry, J., 1926, 1938; A,, 1026; H. vonEuler and I. Hedstrom, Arkiv Kerni, Min., Beol., 1926, 9, No. 17, 1 ; A., 714ORUANIC CHEMISTRY .-PBRT I. 87oxide-ring structure of free glucose. The region of maximumstability of glucose a t 20" is pa 4.83 and the value of the specificreactivity of the dextrose anion is 66.The curves showing mutarot-ation plotted against p= indicate that glucose functions as a veryweak acid and also as a very weak base.40It is suggested that Fischer's classification of the d- and I-seriesof the sugars breaks down in the case of arabinose, and that for thenormal forms of the aldoses the configuration of the middle groupof the oxide ring (carbon atom 3) is the deciding factor in thisclassification. According to this view,41 the natural arabinosebelongs to the d-series instead of to the 1-series.Disacchar ides.The constitution of maltose has been reviewed during the yearand three papers have been published dealing with the nature ofthe oxide ring and with the position taken up by the biose linking.The diagnosis of the trimethyl glucose separated from the cleavageproducts of heptamethyl methylmaltoside now establishes thepositions of the methyl groups, this fragment being recognised as2 : 3 : 6-trimethyl glucose.42 The effect of the two papers communic-ating this result is to overturn Fischer's structural formula formaltose, which had been supported by the previous diagnosis ofthe above fragment as 2 : 3 : 4-trimethyl glucose.Since this newexperimental work does not, however, differentiate between thealternative formula (I) and (11) for maltose, the determination ofthe structure of this disaccharide remained inconclusive.1 rFH-OH r ~ H - ~ rFH-OH rFH-1 YHaOH 1 YH*OH I I $!"*OH 1 YH*OH'YH*OH '(iK*OH YH*OH 0 YH*OH (II.) I Y,H- $!H*OH I LYH 1 ?".OH IL yH $!H- YH CiH J(1.1CH,*OH CH,*OH CH,*OH CH,*OHThe problem was finally solved 43 by application of experimentalmethods which were independent of the solution based on thediagnosis of the above trimethyl glucose.Maltose was oxidisedto maltobionic acid, which gave on methylation methyl octamethyl-maltobionate (111). By the hydrolysis of this product, crystalline2 : 3 : 5 : 6-tetramethyl y-gluconolactone (IV) was isolated along with40 H. von Euler and A. Olander, 2. anorg. Chem., 1926, 152, 113; A,, 680.41 J. G. Maltby, J., 1926, 1629; A., 822; C. J. de Wolff, Chem. Weekbhd,42 J. C. Irvine and I. M. A. Black, J . , 1926, 862; A., 602; C. J. A. Cooper,1926, 23, 353; A., 940.W. N. Haworth, and S. Peat, &id., p. 876; A,.602.W. N. Hamorth and S. Peat, ibid., p. 309488 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the expected 2 : 3 : 4 : 6-tetramethyl glucose. The recognition ofthe structure of this lactone left no doubt as to the position occupiedby the biose linking in maltose, the constitution of which is nowrepresented by (I).YH*OMe 0 YH*OMe I H*OMe CHmOMe 0VH-OMe I YHaOMe --3 $H.OMe bH*OMe I$!H*OMe VH-J YHaOMe bH-OMe ICH,-OMe CH,.OMe CH,*OMe CH,.OMeYOae ~I-YH- -l YO-7VH- _I YHaOMe YHsOH ----f bH- J(111.) (IV.)This result ascribes t o maltose the same structural formula asis given to cell0biose,4~ the difference being that whereas theformer is a glucose-a-glucoside the latter is a glucose-p-glucoside.Furthermore, a direct determination of constitution which excludesthe use of methyhted products confirms this cellobiose structure.Cellobiose was degraded 45 through the octa-acetate of cellobiono-nitrile t o the gluco-arabinose (VI), which yielded three isomericcrystalline hepta-acetyl derivatives and also a crystalline sugar.Finally, the degradation t o a glucotetrose (VII) was reached, andthis product was found to be incapable of forming an osazone.This circumstance is ascribed to the location of the biose linking a tthe second carbon atom of the tetrose unit, and since this linking ispresumably unimpaired by the successive stages in the degradation,the biose linking in cellobiose is attached to the fourth carbonatom in the reducing hexose residue.It follows, therefore, thatcellobiose has the constitution (V).rTH*OH r-FH- 1 r(iH*OH rGlucose GlucoseI (;H.OH 0 s VH*OH yH.0J-J 0 residue rresidueO ~ H ~ O H 1 ~ H - O H 0 - OGH----I 1 CH-J ~ H .O H 1 1 +H.OH+LAH +H- LCH,~)H,.oH CH,.OH(V.) (VI.1 (VII.)CHmOH 044 W. N. Haworth and E. L. Hirst, J., 1826, p. 1858; A., 1126; W. Chad.M. G. ZemplBn, Bet., 1926, 50, 1254; A., 822.ton, W. N. Haworth, and S. Pest, &id., p. 89; A., 273ORQANIC CHEMISTRY .-PART I. 89The application by this author of a similar method to the case oflactose led to the isolation of a galacto-arabinose (IX) which fieldeda phenylosazone, and also of a galacto-erythrose (X) which wasincapable of yielding an osazone. From these experiments, itfollows that lactose has the constitution (VIII).These resultsconfirm the constitutional formuls already ascribed to cellobioseand lactose by earlier workers.46Closely associated with the question of the relationship of cello-biose to the structure of cellulose is the isolation of celloisobiose andcellotriose from the polysaccharide. Revised details for the isolationof these cleavage fragments are the properties havingpreviously been ill-defined. The disaccharide which has beendesignated celloisobiose is considered to represent a constituent partof the cellulose molecule, but its complete characterisation and itsstructure remain as a problem for the future. The hypothesis48that cellobiose and celloisobiose should be considered as one struc-turally identical pair and maltose and isomaltose as a secondsuch pair does not seem to be warranted by the facts alreadyobserved.49Fischer’s isomaltose, prepared by the action of acid on glucose, isshown to be a mixture containing also gentiobiose.The purifiedisomaltose has been characterised and its synthesis achieved fromdi-bvog1ucosan.m Gentiobiose has already been synthesised byenzyme action on glucose, but a new synthesis 51 is now reported bythe use of methods which leave the constitution open to nodoubt.Condensation of 2 : 3 : 4-tribenzoylglucosyl fluoride (XI) iseffected with acetobromoglucose (XII) in presence of silver oxide.From the crystalline product the acyl groups are removed bymethyl-alcoholic ammonia, yielding gentiobiosyl fluoride, andthis gives gentiobiose on boiling in aqueous solution with calciumcarbonate.The disaccharide was identified by its octa-acetateand its osazone, and its synthesis by these methods confirms the( 6 G . ZemplBn, Be?., 1926,59,2402 ; A., 1229 ; W. N. Haworth and Miss G. C.Leitch, J., 1918, 113, 189; W. Charlton, W. N. Haworth, and S. Peat, Eoc. cit.47 H. Ost, 2. angew. Chem., 1926, 39, 1117; A., 1127.4 * J. C. Irvine and Black, Zoc. cit.40 W. N. Haworth and S. Peat, Eoc. cit.A. Georg and A. Pictet, Helv. China. Acta, 1926, 9, 612; A., 823; A.Pictet and A. Georg, Compt. rend., 1926, 181, 1035; A., 1926, 152; A, Georgand A. Pictet, Helv. Chim. Acta, 1926, 9, 444; A., 602; H. Pringsheim,J. Bonde, and J. Leibowitz, Ber., 1926, 59, 1983; A., 1127; J. V. Iqajev,Chem. Listy, 1926, 20, 251; A., 714; H.Berlin, J. Amer. Chem. Soc., 1926,48, 1107; A,, 602.51 B. Helferich, K. Bauerlein, and F. Weigand, Annalen, 1926, 447, 27;A., 386; B. Helferich, W. Klein, and W. Schafer, ibid., p. 1990 ANNUAL REPORTS ON TEE PROGRESS OF CHEMISTRY.constitution (XIII) already assigned to gentiobioae by earlierworkers.52[JZtBzYH-OBz I YH*OBzLYHCH,. OH CH,*OAcA striking example of a Walden inversion which emphasises theneed for caution in selecting methods of investigation of the sugarsis encountered in the interaction of aluminium chloride and lactoseocta-acetate.53 Under specified conditions, a 20% yield of thechlorohepta-acetate of a new disaccharide, neolactose, is obtained,which is recognised as d-galactosido-d-altrose.The reactioninvolves the inversion of the groups 2 and 3 in the reducing glucoseresidue in lactose. This is not a solitary instance, since a similarinversionThe constitution assigned to sucrose in earlier investigations isadversely affected by the new experiments already commented onin this Report (p. SO), which invalidate the oxide-ring structureapplied to normal fructose. The methylated representative of thelatter sugar is crystalline tetramethyl'fructose, and the constitutionformerly assigned to it by Irvine and Patterson h5 on the basis of itsoxidation was (XIV).(XI.) (XII.) (XIII.)has been effected also with cellobiose.CH,*OBle(XIV.) (XV.)This is considered to be erroneous and the new constitution(XV) is now allocated by Haworth and Hirst 56 to this importantreference compound.In the latter paper, it is indicated that the62 W. N. Haworth and B. Wylam, J., 1923,123, 3120.63 A. Kunz and C. S. Hudson, J. Arne?. Chem. SOC., 1926, 48, 1978, 2435;64 C. S. Hudson, ibid., p. 2002; A., 941.6 6 J., 1922, 121, 2696; W. N. Haworth and E. L, Hiwt, J., 1926, 1868;66 LOC. cit.A., 941, 1127.A., 1126OBUAlIC CHEMISTRY ,-PART I. 91interpretation of earlier results on the oxidation of the isomericfructose derivative, the liquid tetramethyl y-fructose, must also beerroneous, since the formula (XV) now definitely reserved for thenormal fructose derivative had previously been applied to thissugar by Haworth and W. H. Linnell.57The resdjustment of the oxide-ring formula of tetramethyly-fructose, a product derived from methylated sucrose, remainsto be effected.The constitution (XVI) is tentatively ascribed toBucrose by Haworth and Hirst, indicating the fructose residue asa butylene oxide. A criticism of the earlier sucrose formula ispresented also by M c O ~ a n . ~ ~ This author suggests that the liquiddegradation product obtained from tetramethyl y-fructose is aketodimethoxypropanecarboxylic ester, and on the basis of thisinterpretation the formula (XVII) is suggested for sucrose, whichrepresents the fructose residue as a propylene oxide. This con-clusion appears to be based, however, on the older formula fornormal tetramethyl fructose.Turanose and melezitose have been the subjects of a constitutionalstudy by two authors and it appears to be established that the lattertrisaccharide has its three hexose units arranged in the sequenceglucose-fru~tose-glucose.~~ Completely methylated melezitoseundergoes hydrolysis with acetic acid to give normal tetramethylglucose and a product which on methylation gives octamethylturanose.Hydrolysis of the latter with mineral acid leads to normaltetramethyl glucose and a trimethyl y-fructose, which is consideredto be the 1 : 3 : 4-isomeride. The author 60 interprets these resultson the basis of the new butylene-oxide structure for the y-fructoseunit, turanose being indicated by the symbol (XVIII) and melezitoseby (XIX).6 7 J., 1923,123, 294.6s G. McOwan, J., 1926, 1737; A., 941.6e R. Kuhn rand G. E. von Grundherr, Be?., 1926, 59, 1655; A., 1127.G .Zemplh, ibid., p. 2230, 263992 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.YH,*OHry.OH A ?"-OHCH,-O.Glucose residue'EiFGlucose (XVIII.) residue (XIX.)Starch.Although maltose is the characteristic product of the enzymecleavage of starch, this disaccharide does not appear to be formedby either the acid hydrolysis or the acetolysis of the polysaccharide.On the contrary, two quite different acetates are produced accordingas the inner or the outer substance of the starch granule is subjectedto acetolysis. The first of these, amylose, yields the acetate ofdihexosan, an anhydro-disaccharide which can be hydrolysed togive the disaccharide amylobiose,l whilst amylopectin, the secondstarch substance, yields initially the acetate of trihexosan.Bothdihexosan and trihexosan are also obtained by heating amylose andamylopectin, respectively, with glycerol.2 Furthermore, hydrolysisof the starches with cold concentrated hydrochloric acid leads tothe isolation of the reducing sugars amylobiose and amyl~triose,~which are characterised through their osazones as a disaccharideand .a trisaccharide, and amylobiose appears to be quite differentlyconstituted from maltose.Again, whilst under special conditions starch can be completelydegraded by ferments to maltose, the more usual procedure yields75% of the latter biose along with a limiting product, a dextrin,which is now identified with trihexosan,J and by the use of a malt-amylose of a special character, the inner starch material, amylose,gives rise to dihexosan as the limiting product.5 The relationshipof trihexosan to dihexosan is apparent in that from the former, bythe action of emulsin,6 dihexosan can be isolated along with thepolymeride tetrahexosan.Then, by the agency of either mineralacid or barley diastase, dihexosan is converted into maltose. Ifdihexosan were to be identified with anhydromaltose as is suggested,then the internal structure of these products could be easily eluci-A. Pictet and R. Jahn, Helv. Chim. Acla, 1922, 5, 640; A., 1952, i, 987;1 H. Pringsheim, Ber., 1926, 50, 3010.H. Pringsheim and K. Wolfsohn, Ber., 1924, 57, 887; -4., 1924, i, 714.3 IF. Pringsheim, Ber., 1924, 57, 1581.6 K. Sjoberg, Ber., 1924, 57, 1251; A., 1924, i, 1169.H.Pringsheim and A. Beiser, Biochem. Z., 1924, 148, 336.A. Pictet and R. Salzmann, Hela. Chisw. Acta, 1925, 8, 948; A., 192652; compare .4., 1924, i, 1288ORGANIC CHEMISTRY .-PART I. 93dated, since the constitution of maltose is now finally decided.That there must be some close connexion between these productsand maltose is confirmed, inasmuch as hexahexosan is convertedby the agency of acetyl bromide into hepta-acetyl m a l t ~ s e , ~ and isalso transformed directly into maltose by amylase or emulein.Some progress has been made in the study of these breakdownproducts. For example, trihexosan undergoes partial methyl-ation,s giving a monomethyl derivative which is considered to behomogeneous. Since this yields on hydrolysis 6-monomethylglucose, proving that the terminal primary alcohol residue in theassociated glucoses is not concerned in the internal linkings, theisolation of this product renders doubtful the formula, first proposedby Pringsheim and L e i b o ~ i t z , ~ containing internal 1 : 6-oxiderings.A quantitative conversion of starch, amylose or amylopectin, intoglucose occurs by the use of a combination of pancreatic and maltamylases ; 10 whilst a technical ferment, “ biolase,” transformsstarch, but not amylobiose, into glucose, accompanied by ti smallamount of a reducing trisaccharide 11 which may be identical withthe P-glucosidomaltose obtained by Ling and Nanji, although thebehaviour of the latter towards enzymes is not in agreement withprevious results.The view that starch, when purified, can behydrolysed by salts, amino-acids, and peptones is now said to beerroneous .12Amylobiose is intimately related to dihexosan, and is now obtain-able also through a-tetra-amylose, The methylation l3 of amylo-biose seems to be arrested when only six methyl groups have beenintroduced, and that this is an example of steric hindrance only issuggested in that one further hydroxyl residue can be protected byintroducing an acetyl group. Hydrolysis of hexamethyl amylobiosesucceeds only in establishing the structure of one half of the mole-cule, since crystalline 2 : 3 : 4 : 6-tetramethyl glucose was isolated ;the remaining residue resembles a 3-monomethyl methylglucosidewhich behaves rather like a y-sugar derivative.The constitutionof this interesting biose is thus nearing solution.The relationships of dihexosan and amylobiose to the newP. Castan and A. Pictet. ibid., p. 946; A., 52.R. Kuhn and W. Ziese, Ber., 1926, 59, 2314; A., 1230.Ber., 1924, 57, 884; A., 1924, i, 714.lo H. Pringsheim and J. Leibowitz, Ber., 1926,59, 991 ; A,, 715; R. Kuhn,BeT., 1924, 57, 1965; A., 1925, i, 11; Annalen, 1925, 443, 1; A . , 1925, i,636.l1 H. Pringsheim and E. Schapiro, Ber., 1926,59, 996; A., 715.l2 K. Takene, Biochem. Z., 1926, 175, 241; A., 1059.lS H. Pringsheim and A. Steingroever, Ber., 1926,159, 1001 ; A,, 71594 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.structural formula for maltose have been considered, and adoptingthe revised formulae for glucose and y-glucose, Pringsheim l4advances the tentative suggestions :Maltose is regarded as a transformation product of dihexosanor trihexosan involving hydrolysis and rearrangement of the oxiderings, and thus the occurrence of maltose as an essential residue inthe starch molecule is considered improbable.In view of the funda-mental discoveries recorded in the ensuing section dealing with theelementary unit of cellulose, Pringsheim hesitates to apply theabove results in the sense of attributing to either dihexosan ortrihexosan the character of the ultimate unit of starch. The latterhypothesis is doubtful for other reasons also,l5 depending on theapplication of Hudson's views to the stereochemical relationships ofthese products.The synthesis of starch in nature is attributed tothe formation of a labile glucose having the property of directlyassimilating carbon dioxide.Earlier experiments on the investigation of methylated starch l6are supplemented by the preparation of a completely methylatedtrimethyl starch17 which is found to undergo conversion into2 : 3 : 6-trimethyl methylglucoside. Alternative possibilities forthe molecular unit of starch are discussed and in the view of theauthors this unit must contain nine or a multiple of nine hydroxylgroups. The simplest unit is thus considered to be a trihexosan ora hexahexosan, and suggested formulae, e.g. (XX), are communi-cated. The same authors consider that maltose residues occm inthe starch complex, and B formula for maltose differing structurallyfrom cellobiose is adopted (compare p.$8). Thus if cellobiose isgiven an amylene-oxide structure, maltose is said to be constitutedon the basis of the presence of a butylene-oxide group in thereducing hexose residue. These views differ essentially from thoseof Pringsheim, who regards trihexosan and dihexosan as containing14 Ber., 1926, 59, 3012.16 H. Pringsheim and J. Leibowitz, Bw., 1926, 68, 2808; A., 1926, 276.16 Ann. Report, 1922, 19, 81.1' J. C. Irvine and J. Maodonsld, J., 1928, 1602; A., 823ORGANIC CHEMISTRY .-PART I, 96no pre-formed maltose groupings, and deprecates the identificationof the hexosans with the fundamental unit of starch.7 0 IryH-O--CH.CH(OH)CH( OH).CH.CH*CH,*OH0 YHOH(xx*) I YH-OH 0L'iH~H-O-CH*CH(OH)CH(OH)*CH.CH,.OHCH,.OH L- 0 -ICellulose.Experiments of the greatest significancc in relation to the CODstitution of cellulose are reported by Hess and Pringsheim and theirco-workers.A redetermination of the molecular weight of cellulosediacetate in an acetic acid solution, from which dissolved oxygenis eliminated by a vacuum, gives a mean value corresponding closelywith that required for a glucose-anhydride diacetate.l8 This valueremains constant for some days and then gradually increases toinfinity. There appears to be no evidence of the intermediateformation of the dimeride, (C6HlD06)2, and the material isolatedfrom the solutions is identical with the initial crystalline substance,undergoing the same sequence of changes when redissolved. Thisbehaviour is not restricted t o the cellulose diacetate, but extendsalso to crystalline cellulose triacetate and lichenin triacetate.In-asmuch as these cellulose acetates are convertible into pure cellulose,and this again into acetates without apparent change in structure,these results furnish strong evidence in support of the view of Hessthat the structure of cellulose may be represented by a glucoseanhydride which, differing from other glucosans, is capable of swell-ing and is sparingly soluble in water.When cellulose triacetate is heated in presence of naphthalenea t 235", the molecular weight is diminished to the value of 288,corresponding with the triacetate of anhydrogluc~se.~~ Thisdiminution in complexity is accompanied by increased solubilityin acetone and by a fall in viscosity, although there is no change inrotation.Removal of the acetyl groups discloses an anhydro-glucose which is termed cellosan and is soluble in water. At 73-80",the molecular weight is in agreement with the simple formulaSimilarly, lichenin acetate is transformed by an analogousl8 K. Hese and G. Sohultze, Innalen, 1926, 448, 99; A., 715; K. Hess,la H. Prinffsheim, J. Leibowitz, A. Schreiber, and E, ICasten, Annden,C6Hl005.Kol1.-Chem. Beih., 1926, 23, 93; A., 1127.1926, 449, 163; A., 94296 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.procedure into lichosan,20 which also is a glucose anhydride. Theclose relationship of lichenin to cellulose is apparent from theconversion of the former into cellobiose by ferments.Moreover,cellulose hydrate, oxycellulose, generated from viscose by perman-ganate, and hydrocellulose, obtained by reduction of viscose, aIlgive Rontgen diagrams identical with that of lichenin, thus provingthat these products have the same crystalline constituents.21 Theconversion of cellulose into lichenin (viscose cellulose) is regarded asa change of modification only. Cellosan and lichosan are con-sidered to be the elementary units of cellulose and lichenin, and thusthese polysaccharides are regarded as the products of associatedglucose anhydrides, a hypothesis which was previously advanced onthe basis of the experimental work of Hess 22 on the nature of thecopper-ammine solutions of cellulose.Cellosan appears to undergoreassociation in solution, and it is significant that the specificrotations of cellulose and cellosan are identical in similar solvents,as are also the rotations of lichenin and lichosan. The reassociationof the elementary units thus seems to call into play no readjustmentof grouping or of intra-molecular valen~y,~3 and this feature providesabundant ground for speculation as to the nature of the forcespromoting molecular aggregation.Considerable light is thrown on this problem by the study of thepolymerisation off ormaldehyde. Staudinger has isolated a long seriesof oxymethylene diacetates 24 by the action of acetic anhydride onpolymerised formaldehyde. Nineteen apparently individual pro-ducts were recognised of the generaltypeCH,*CO.[O*CH,],.OCOCH,,in which the value of x varies from 1 to 22, most of these being low-melting solids.A corresponding series of oxymethylene-dimethylethers has also been isolated in which the magnitude of x rangesfrom 6 to 75. This study is supplemented by the consideration of thegeneral problem of polymerisation as applied to vinyl derivatives,styrene, and caoutchouc.The acetolysis of cotton cellulose, if allowed to proceed to a stageimmediately preliminary to the formation of cellobiose octa-acetate,gives an amorphous powder which is soluble in organic media anddextrorotatory. This wits subjected to deacetylation and methyl-ation, and the main product consisted of a colourless glass whichwas recognised as essentially a tri(trimethy1 1 : 4-anhydro-glucose)20 H.Pnngsheim, Bw., 1926, 59, 3008.a 2 Ann. Repom, 1924, 21, 91 ; 1925, 22, 100; compare S. M. Neafe, J . Tezt.23 H. Pringsheim and J. Leibowitz, Ber., 1926, 58, 2808; A., 1926, 275.24 Ber., 1926, 59, 3019.E. Ott, Helv. Chim. Actu, 1926, 9, 31; A,, 387.Inst., 1926, 16, ~ 3 6 3 ; A., 1926, 241ORGANIC CHEMISTRY.-PART I. 97mixed with a methylated trisac~haride.~~ An analysis of themixture agreed with a 70% content of the former and 30% of thelatter, as did also molecular-weight determinations. Hydrolysisof this mixture of products yielded 2 : 3 : 6-trimethyl glucose(84%) and also 2 : 3 : 4 : 6-tetramethyl glucose (7%). Evidence ofthe presence of an acetylated disaccharide other than cellobiosewas also recorded.The authors conclude from these results thatsupport is given to the application of the poly(1 : 4-anhydro-glucose) structure to cellulose, and they modify their earlier sugges-tion of four possible constitutional formula by the elimination ofidentical representations and by the introduction of amylene-oxiderings into the glucose residues. The direct evidence available is tosome extent obscured by the non-homogeneity of the originalacetates.Another series of investigations 26 on cellulose indicates the easeof methylation which is secured by employing cellulose regeneratedfrom viscose or cellulose acetate. Also by utilising depolymerisedcellulose, obtained as hydrocellulose from viscose staple fibre, ninemethylations with methyl sulphate sufficed to introduce a completecomplement of methyl groups corresponding t o trimethyl cellulose.The same result is obtained when dimethyl cellulose prepared fromviscose cellulose is first acetylated and then twice methylated.Themost striking result appeared to be that obtained by methylatingcellulose triacetate from cotton linters, inasmuch as a trimethylcellulose was isolated after only six methylations. This product issoluble in acetic acid, and almost completely dissolves in cold water.Determinations of molecular weight give 800 as the lowest value fora hydrocellulose.Inulin.Acetylation of inulin in presence of pyridine a t temperaturesbetween 20" and 60" leads to an 80% yield of inulin hexa-acetate,m.p. 135". Molecular-weight determinations indicate that thisproduct is hexa-acetyl difructose anhydride,27 and the view thatinulin is built up from the unit Cl2H,,O1, is supported by theseresults. Hydrolysis of the hexa-acetyl derivative regeneratesinulin, which in turn gives back the hexa-acetyl difructose anhydrideon reacetylation. Inulin has been dissolved in liquid ammonia, andit is remarkable that from this solution it can be recovered un-changed.2s J. C. Irvine and 0. J. Robertson, J., 1926, 1488; A,, 823.z6 E. Hewer and N. Heimer, Cdlulosechem., 1926, 6, 101; A., 1926, 602;57 M. Bergmann and E. Knehe, AnnaZen, 1926, 449, 302; A., 1230; M.H. le B. Gray, Ind. Eng. Chem., 1926, 18, 811; A,, 1026.Bergmann, Be?., 1926, 69, 2079.REP.-VOL.X-. 98 ANNUdL REPORTS ON !FEE PROGRESS OB OHEMISTRY.A c i d s , F a t s , a n d W a x e s .Ultra-violet light decomposes a boiling solution of formic acidwith the production of hydrogen and carbon dioxide and also intowater and carbon monoxide.1 The intermediate formation of methylalcohol or formaldehyde has been disputed, but it is established thatif the formic acid is sufficiently concentrated, the greater part of thenascent hydrogen and carbon monoxide reacts with the formic acidto give formaldehyde, etc.lQ The catalytic decomposition of formicacid in presence of metals is largely influenced by the dispersivity ofthe latter, and falls rapidly as the catalyst becomes aggregated.Oxalic acid undergoes electrolytic reduction to glyoxylic acid insolutions containing 2% of sulphuric acid.By continuous additionof oxalic and sulphuric acids during the progress of the electrolysisa solution containing more than 12% of glyoxylic acid has beenprepared. A detailed study 2 of this process is communicated,including the methods of isolation of the product. Pyruvic acidmay be obtained 3 in yields of 90% by the oxidation of methylglyoxalwith bromine water. Propiolic acid is convenientIy prepared bythe action of carbon dioxide on sodium a~etylide,~ and the purecrystalline acid obtained by this method can be kept indehitelywithout polperisation occurring. Propiolic anhydride is readilyobtained from the sodium salt by the agency of thionyl chloride.By employing the same procedure, and using disodium acetylide,acetylenedicarboxylic acid is obtained.Oxidation of the sodium derivative of acetowetic acid or its ethylester by means of hydrogen peroxide yields mainly a-hydroxy-acetoacetic acid or its corresponding enol form.6 This acid graduallypasses into acetylcarbinol by loss of carbon dioxide, and by sub-sidiary reactions acetonylacetone, glyoxylic acid, and other pro-ducts are formed.The possibility of the formation of carbohydratein the living organism from acetoacetic acid is discussed on thebasis of these results. The addition of ethyl diethoxyacetate insuccessive portions to sodium ethoxide in ether gives rise to theester enolate, which decomposes in presence of ice, yielding di-cthoxymethylene.6 The same product may also be obtained byconverting ethyl formate similarly into the sodium derivative ofhydroxyethoxymethylene, C(ONa)OEt, followed by chlorinationE.MiilIer and H. Hentschel, Be?., 1926, 59, 1854; A., 1124.W. Mohrschulz, 2. Elektmchcm., 1926, 89, 434; A,, 1110.C. Neuberg and G. Gorr, Biochem. Z., 1926, 186, 442; A., 272.F. Straus and W. Voss, Ber., 1926, 60, 1681; A., 1124.P. W. Clutterbuck and H. 5. Reper, Bbchem. J., 1926, 20, 69; &, 427.11. Scheibler, Ber., 1926, 59. 1022; A., 711.l5 A. J. Allmand and L. Reeve, J., 1926, 2853ORGANIC CHEMISTRY .-PART I. 99with phosphoryl chloride and treatment with sodium ethoxide.The products appear to be true derivatives of carbon monoxide andcompounds of bivalent carbon.Thallous salts of organic acids have been prepared by titrationwith thalloua hydroxide solution, and many of these crystallinesalts are described. Their utility in synthetic work is illustrated,'and they possess obvious advantages over the silver salts as a meansof preparing the corresponding esters by digestion with alkglhalides.Small quantities can easily be manipulated and traces ofthe acids readily recognised owing to the facility with which esteri-fication proceeds. Palmitic, stearic, and oleic acids give thalloussalts, m. p.'s 115", 119', and 78-82', respectively, and these showdouble m. p.'s and appear to be anisotropic liquids between thesepoints. Tartaric acid gives a tetrathallium derivative, losing,however, two of the metallic radicals by the agency of carbondioxide.The two stereoisomeric hydroxystearic acids (m.p. 95" and 132')may be prepared by the oxidation of oleic acid and elaZdic acid,respectively, by concentrated hydrogen peroxide in acetic acid oracetone solution.8 Under the same conditions, methyl oleate andelaldate give the corresponding esters of the two isomerides. If theoxidation be conducted, however, under alkaline conditions thedihydroxystearic acid having the higher m. p. is obtained from oleioacid, indicating 8 transformation of the geometric isomerides.By an application of the method described in the last Report(p. SO), r-ketosteario acid has been synthesised.9 Reference to thefreezingpoint curve for mixtures of 1-ketostearic and K-ketostearioacids indicates that the product obtained by treating stearolic acidwith sulphuric acid and then with water consists of a mixture ofthese two acids.In addition to the above, the following have also been preparedby the same authors : 6-ketomyristic acid and its oxime, K-ketonona-decoic acid and its amide, and K-ketobehenic acid and its amide.Partial hydrogenation of stearolic acid in presence of nickel hasgiven rise to oleic acid, and by the same procedure behenolic acidyields erucic acid.10 The corresponding products obtained byreduction with zinc and acetic acid are elaidic and brassidic acids.It is argued on thermochemical grounds that no secondary changesare involved in the former of these methods of reduction, and7 G.H. Christie and R. C. Menzies, J ., 1925, 127, 2369; A., 1926, 66;C. M. Fear and R. C. Menziee, J . , 1926, 937; A,, 604.8 T. P. Hilditch, J., 1926, 1828; A,, 938.9 G. M. Robinson and R. Robinson, ibid., p. 2204; A., 1024.10 A. Gonz&lez. Anal. Fk. Quh., 1926, 24, 166; A., 712100 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.therefore that oleic and erucic acids have the cis-codguration whilstelaidic and brassidic have the trans.Incomplete hydrogenation of castor oil in presence of a nickelcatalyst a t 80a leads to a convenient process 11 for the preparationof ethyl h-hydroxystearate, m. p. 51". After reduction, the mixedglycerides are converted into the corresponding ethyl esters andrecrystallised. Either by heating ethyl A-hydroxystearate withp-naphthalenesulphonic acid a t 220" or by treating the free acidwith thionyl chloride, and then with ethyl alcohol, this is trans-formed into the isomeric ethyl AA-octadecenoate, and from this bothforms of the related acid are obtained, the elaldic type havingm.p. about 40", and the oleic type m. p. about 10". The latter isisomerised partly to the elafdic type by nitric acid a t 25" in presenceof mercury. Ethyl Xp-dibromo-octadecanoate readily loses 1 mole-cule of hydrogen bromide to give ethyl bromo-Ah-octadecenoate,but under more drastic conditions, using alcoholic potassium hydr-oxide, AA-octadecinenoic acid, m. p. 34*2", is produced. Oxidationof the acetylenic acid with alkaline permanganate leads to decane-aK-dicarboxyh, nonane-at-dicarboxylic, sebacic, and hexoic acids,whilst further successive oxidation with chromic acid gives hexoic,valeric, and decane-ah.-dicarboxylic acids.It would thus appearthat elimination of water from A-hydroxystearic acid occurs ex-clusively to form the AA-unsaturated acid.The acid, C,,H,,O,, which is designated nervonic acid 12 and isobtained by hydrolysis of the cerebroside isolated from humanbrain, yields on reduction with hydrogen and colloidal palladium asaturated fatty acid, m. p. 88". This is said to be identical withn-tetracosoic acid. The hydrolysis of certain cerebrosidefractions gives rise to a new acid, C24H4603, which is probably anunsaturated hydroxy-acid.From the crude arachidic acid prepared from arachis oil, ahexacosoic acid, C,,H,,O,, of m.p. 79" has been isolated l3 andthis is probably identical with cerotic acid from beeswax. Theunsuspected presence of this acid explains the difficulties experiencedin isolating lignoceric acid, C,,H,,O,, and also the discrepanciesobserved as t o its physical constants. The m. p. of the latter isgiven as 80.5-81". An X-ray examination1, of the hexacosoicacid confirms this observation.Crystalline stearolactone 15 is formed as one of the products of11 A. Gr6n and W. Czerny, Ber., 1926, 59, 54; A., 269; compare Thornsl a E. Klenk, 2. physiol. Chem., 1926, 157, 283, 291; A., 1124.1s D. Holde and N. N. Godbole, Ber., 1926, 59, 36; A., 268.14 G. T. Morgan and E. Holmes, Nature, 1926, 117, 624; A., 712.1s A. Blumenstock, Monatsh., 1926, 48, 333; A., 697.snd Decked, A., 1921, i, 219ORGANIC CHEMISTRY .-PART I.101the action of zinc chloride on oleic acid, and also by sulphonation ofpure oleic acid followed by distillation and fractional crystallisation.Not only oleic acid, but also the unsaturated acid of linseedoil, is reduced by the action of a methyl-alcoholic solution ofhydrazine on fats.16 The products are &st isolated as the hydr-azides, and the free acids are obtained by heating these with sulphuricacid and benzaldehyde.Polymethylenedicarboxylic acids containing 11-19 carbon atomsin the chain and designed for conversion into the correspondingketones were prepared by methods 1’ which clearly indicate theirconstitution. Thus nonane-w-diol, prepared by the reduction ofazelaic ester by the action of sodium and alcohol, and also decane-aK-diol, were converted into the dibromides and thence, through thecyanides or by condensation with ethyl malonate, into the highercarboxylic acids.The esters of these were reduced to the corre-sponding glycols, which provided new materials for similar synthesesA variation of this method was also employed ; thus the dibromo-compounds, through their magnesium derivatives, were condensedwith monochlorodimethyl ether, yielding the dimethoxy-derivativesof hydrocarbons containing two more carbon atoms in the chain :IliCgBr*[CH,],*MgBr + 2CH,C1*OMe+MeO*[CH2]n+2*OMe. By theaction of dry hydrogen bromide on the latter, the correspondingdibromo-derivatives were obtairted.The compounds isolated by these methods range from nonane-to heptadecane-dicarboxylic acids.Them. p.’s of the even-numbereddicarboxylic acids fall from the one acid to the next, whilst them. p.’s in the odd-numbered series rise, so that the curves for thetwo series of m. p. tend to converge.Bothvarieties give, when boiled with aqueous sodium carbonate, aa’-dihydroxysuberic acid.18 When ethyl ua’-dibromosuberate isdigested with methyl-alcoholic potassium hydroxide, it yields theopen-chain unsaturated acid, suberocolic acid, reduction of whichyields two forms of dihydrosuberocolic acid. Other products ofthis treatment with alkali are cyclohexene-1 : 2-dicarboxylic acidand aa’-dimethoxysuberic acid. Dimethoxyazelaic acid anddihydroxyazelaic acid in stereoisomeric forms were isolated bysimilar treatment of ethyl mi’-dibromoazelate.Synthetic waxeshave been prepared lo by heating mixtures of the higher acids andalcohols in iron vessels or in the presence of molten tin, the esterA second form of ad-dibromosuberic acid has been isolated.l6 J. van Alphen, Rec. trctw. chim., 1925, 44, 1064; A., 1926, 46.P. Chuit, Helv. Chim. Acta, 1926, 9, 264; A,, 499.l8 F. R. Goss and C . K. Ingold, J., 1926, 1471; A., 820.l9 A. Griin, E. Ullrioh, and F. Krezil, 2. angezo. Chem., 1926, 39, 421; A.,690102 ANNUAL REPORTS ON THE PEOQRESS OF UHEMISTJ3Y.mixture so formed having the consistency, plasticity, and con-choidal fracture of most waxes. The pure alcohols also combinewith the acid chlorides when heated in an atmosphere of carbondioxide and give almost quantitative yields of wax esters.Thefobwing have inter alia been prepared : ptricosyl myristate,palmitate, and stearate, and the corresponding e-heptacosyl,x-hentriacontyl, and a-pentatriacontyl esters.The complex process involved in the electrolysis of potassiumacetate has again been the subject of inquiry,ZO and in a recentcommunication the “ discharged ion ” theory as originally proposedby Crum Brown and Walker is supported as against the “ oxidation ”theory. It has been shown that synthesis takes place in non-aqueous solutions to which the oxidation theory cannot be applied.O p t i c a l A c t i v i t y .Of the views put forward respecting the spatial configuration ofthe ammonium salts, those deserving of more serious considerationassign to the four positive radicals attached to the nitrogen atom adisposition which is either tetrahedral or pyramidal, these beingthe only arrangements in which the valencies linking the nitrogenatom with these radicals can be represented as inter-equivalent.Whilst on general grounds the tetrahedral configuration of theammonium salts must be regarded as the more probable, no directexperimental evidence had hitherto been obtained which enabled adefinite decision to be made between this and the pyramidal con-figuration.W. H. Mills and E. H. Warren1 have decided thisimportant question by a successful resolution of 4-phenyl-4’-carbethoxybispiperidinium-1 : 1‘-spiran bromide,in which a pyramidal configuration would be symmetrical whilstib tetrahedral distribution should exhibit dissymmetry.It musttherefore be concluded that, in quaternary ammonium compounds,the four positive radicals are disposed tetrahedrally about thenitrogen atom, the fifth radical being attached as a negative ion.This conclusion is confirmed by the previous failure t o resolvetrimethylenetetrahydroisoquinolinium Salk2 In the case of theamine oxides, Nabc(O), upon which further work is contributed byMeisenheimer and his colleagues, the double bond between oxygenaa D. A. Fairweather and 0. J. Walker, J., 1926, 3111.3 H. 0. Jones and J. G. H. Dunlop, J . , 1912,101, 1748.Annalen, 1926, 449, 188; A,, 1240.J., 1926,127, 2607; A., 1926, 178.J. Meisenheimer, E.Glawe, H. Greeske, A. Schorning, and E. ViewegORGANIC CHEMISTRY.-FART I. 103and nitrogen is semi-polar, the oxygen atom both figuring as thefourth positive radical and taking the place of the negative ion ofthe ammonium salts. Wedekind has found it impossible to effect;t resolution of quaternary ammonium bases with a double linkingat the nitrogen atom, both when the double linking is betweennitrogen and carbon, as in CPh:NMePhI, and when it is situated -*i PhN:NPhBr'between two nitrogen atoms in a ring, as in PhCeN 7Many writers, following Werner, had assumed that the salts ofbivalent metals with 8-diketones and similar substances wereexamples of 4-co-ordination compounds, and that they possessed,therefore, a tetrahedral configuration of which the metallic atomwas the centre.Such structures should clearly give rise t o thepossibility of optical activity due to the normally bivalent metallicitom alone, just as is the case with the octahedral structures ofcorresponding derivatives of normally tervalent metallic atomssuch as cobalt and iron. H. Burgess and T. M. Lowry had demon-strated this probability by an examination of the mutarotation ofberyllium benzoylcamphor ; but their results were perhaps notdecisive owing to the presence of additional optical activity due tocarbon. Now, however, Mills and R. A. Gotts 6 have suppliedfurther proof of the hypothesis by the resolution of the beryllium,copper, and zinc salts of a p-diketone itself free from moleculardissymmetry. They employed benzoylpyruvic acid, effecting theresolution of the metallic salt by coupling it with brucine ar strych-nine.Thus, in the case of beryllium, they obtained both the d-and the 1-rotatory salt of the structure *C'0,Bruc. 60,Bruc.these salts inutarotating in chloroform to the same (d) value. Inaddition, they were able to replace the brucine radical by the di-methylammonium radical, and to show that the salt still retainedthe optical activity due to the metallic atom, although this activityvanished after about 2 hour in alcoholic solution.These experiments seem to furnish positive evidence, not only ofthe tetrahedral disposition of the valencies of the normally bivalentmetallic atom in its 4-co-ordinated state, but also of the existence* In this formula (following Mills and Gotts), the nature of the bondabetween beryllium and oxygen is left undefined.a E, Wedekind, Annalen, 1925, 442, 119; A , , 1928, i, 678.Lowry, J., 1925,127, 1080; A ., 1925, ii, 632.J., 1924, 125, 2081; A., 1925, i, 46; see also I. J. Faulkner and T. M.J., 1920, 3121104 ANNUAL REPORTS ON THE PROURESS OF CHEMISTRY.of a real linking between the metallic atom and the carbonyl oxygenatom of the p-diketone. It will not be forgotten that the metallicderivatives of p-diketones are still sometimes represented as organo-metallic compounds in which the metal is linked to the inter-ketonic carbon atom. In the case of silver acetylacetone, forexample, there is some evidence, although indecisive, in favour ofthe existence of both 0-Ag and C-Ag salts, since alkyl substitutiongives a mixture of the 0-alkyl- and C-alkyl-acetylacetones.If suchwere the case with the benzoylpyruvic acid salts of the bivalentmetals studied, salt formation would be accompanied by the develop-ment in each case of two similar dissymmetric carbon atoms,Current theory, however, is opposed to such a conception of themetallic salts of p-diketones, particularly in the case of a metal likecopper. A resolution of the salt of a symmetrical p-diketonewith a tervalent metal (e.g., a ferric salt) would supply decisiveevidence for the more widely accepted view ; whilst an answer tothe question as to whether or not a copper salt of a symmetrical@-diketone is resolvable would throw light upon the equivalenceor otherwise of the linkings between the metal and the two oxygenatoms of the p-diketone.In this connexion it may be remarked that I.Lifschitz 6 hasclaimed the preparation, from d-alanine and cobaltic hydroxide,of each of the salts d-[Co-d-alanine,] and I-[Co-d-alanine,], in whichthe cobalt atom exhibits octahedral dissymmetry although it is notassociated with atoms or groups in the outer co-ordination sphere.With regard to the distribution of the groups about the copperatom in its 4-co-ordinated compounds, reference may be made toN. Schlesinger's copper salts of bis-imino-acids, which exist inreddish-violet and blue varieties. In this instance, cis- andtrans-isomerism is held to be present, in which case the arrangementof the groups about the copper atom would be planar-unless tetra-hedral nitrogen were assumed ' 5 to be present.R.Charonnat has succeeded in resolving potassium rutheno-nitrosopyridinodioxalate, [Ru(NO)(C,H,N)(C,O,),]K, by doubledecomposition with quinine hydrochloride.The possibility that corresponding compounds of nitrogen,phosphorus, and arsenic might possess similar stereochemicalconfigurations has led to many attempts to resolve arsonium com-pounds, but until recently the only positive result was that recordedby G. J. Burrows and E. E. T ~ r n e r , ~ who obtained a solution of6 Proc, K . Akad. Wetensck. Amsterdam, 1924, 27, 721; A , , 1925, i, 522.7 Ber., 1925, 58, 1S77; A . , 1928, i, 1249.' O H . Reihlen, 2. onorg.Chem., 1926, 151, 7 1 ; A., 467.8 Compt. rend., 1924, 178, 1423; A., 1925, ii, 886.9 J., 1921, 119, 426ORGANIC CHEMISTRY .-PART I. 105phenyl-u-naphthylbenzylmethylarsonium iodide (I) which showeda small dextrorotation. The preparation of the optically pureenantiomorphous modifications of p-carboxyphenylmethylethyl-arsine sulphide (PI), [BIZ1 3-60" and --59", by W. H. Mills and R.Raper,lo definitely proves that arsenic can function as a centre ofdissymmetry.The grouping R,R,R&s:S forms a chemically indifferent complexunlike the tertiary amine and phosphine oxides resolved by Meisen-heimer, which are basic substances. The salt-forming propertiesof this arsenic compound are derived from the substituent carboxylgroup and the arsenic atom is thereby left as far as possible undis-turbed by the process of salt formation and decomposition involvedin the resolution experiments.Here again it seems probable thatthe four radicals are tetrahedrally distributed with respect to thearsenic atom, and that, as in the amine and phosphine oxides, asemipolar doubleibond is present (in this case, between arsenic andsulphur).Of much interest, also, is the resolution11 of a co-ordinatedarsenic compound which contains, apparently, arsenic of octahedraloonfiguration and is possessed of high rotatory power. The sub-stance is tripyrocatechylarsenic acid, discovered by R. F. Weinlandand J. Heinzler,lZ to which has been ascribed 13 the formulaAlthough the discoverers of optical activity in this compoundfavour the above formula, the possibility that the compound iscorrectly represented as having the three pyrocatechyl radicalsoctahedrally distributed around the central arsenic atom should notbe overlooked,l4 in spite of the tenacity with which a molecule ofwater is retained in the acid and in all its salts.The case of arsenic appears to afford the first recorded instanceof an element which gives rise t o dissymmetry of both tetrahedrdand octahedral type.A compound of 4.~0-ordinated boron, disalicylatoboric acid,J., 1925, 127, 2479; A,, 1926, 77.I1 A.Roaenheim and W. Plato, Ber., 1925, 58, 2000; A . , 1925, i, 1412.12 Ber., 1919,52, 1316; 1920, 53, 1365; A . , 1919, i, 442; 1920, i, 778.18 H. Reihlen, A. Sapper, and G. A. Kall, 2.clnorg. Chem., 1925, 144, 218;1 4 Compare W. H. Milk and R. A. Gotts, loc. oit.A., 1925. i, 912.D106 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.[B(O,C*C,H,*O),]H, in which boron possesses a tetrahedral configur-ation, has been resolved l6 by means of its strychnine salt.The existence of the semipolar double bond, poatulated byLomy l6 some three years ago, has now been established by twoindependent experimental methods, depending respectively onthe study of molecular volumes and on the detection of moleculardissymmetry. By making use of the function yli4M/(D - d ) (wherey = surface tension, M = mol. wt., D = density of liquid, d =density of vapour), S. SugdenI7 compares molecular volumes a tequal surface tensions. The value of this function, known as theparachor, is increased by 23 units by each non-polar double bond,whatever the atoms which it joins, e.g., in >C=O, >C=C<,>C=N-, -N=O, but the semipolar double bonds in the systems>SO, 3N0, and PPO produce a minute decrement of molecularvolume.18 In this way, the nitro-group was shown to contain onlyone non-polar double bond, whilst the sulphinates, sulphonates,and sulphates do not contain any.The importance of these observations is seen in the discovery ofoptical activity in compounds which have only three groups attachedto a central sulphur atom.The demonstration by H. Phillips l gthat the sulphinates can be obtained in optically active forms, asin the case of ethyl p-toluenesulphinate, provides substantialexperimental evidence that the constitution of this ester is notaccurately represented by the usually accepted formula (I).L S < , + OEt (11.)7 7If the oxygen and the sulphur were united by a symmetricalnon-polar double bond, the compound would, on the basis of thoolder space formulq be obviously symmetrical.This formula (I)is also in codict with the postulates of the newer theories of valency,since the presence of a non-polar double bond between the sulphurand the sulphoxyl oxygen atom would create a surplus of vdency16 J. Boeseken and J. Meulenhoff, Proc. K . B k d . 'CVe&mch. Amsterdam,1924, 27, 174; A., 1924, i, 776; J. Meulenhoff, 2. anorg. Chem., 1925, 142,373; A , , 1525, i, 920.16 J., 1923, 123, 822.J., 1924,126, 1177; A., 1524, ii, 662.S.Sugden, J. B. Reed, and H. Wilkins, J., 1926, 127, 1626; A , , 1925,Ibid., p. 2552; A,, 1926, 159.ii, 536ORGANIC CHEMISTRY.-PART I. 107electrom*(lO instead of 8) in the valency shell of the sulphur atom.Since the determination of the molecular parachor of ethyl dl-p-toluenesulphinate revealed that the sulphur and the oxygen werelinked by a semipolar double bond, formula (11) was adopted asmore accurately representing the constitution of this. ester. Thenewly-discovered dissymmetric ester molecule can therefore beconsidered as having a tetrahedral configuration in which theapex is occupied by the positively-charged sulphur atom, twoother corners by the p-tolyl and the ethoxy-group, respectively, whilstthe remaining corner is occupied by the oxygen atom, united tosulphur by a semipolar double bond. From such considerations,P.W. B. Harrison, J. Kenyon, and H. Phillips 20 were led to revisethe accepted formula (111) for the sulphoxides and to suggest a newformulation (IV) which carried witah it the implication that mixedsulphoxides should exist in an optically active state.4’-Amino-4-methyldiphenyl sulphoside (V) and m-carboxy-phenyl methyl sulphoxide (VI) were prepared and resolved intoenantiomorphous modifications.It is to be noted that the oxidation of the active sulphinates andsulphoxides to sulphonates and sulphones, respectively, results indisappearance of the optical activity.It may now be considered as definitely established that the fourthvalency of quadrivalent sulpbur differs from the three other valencies.This experimental fact is in agreement with the electronic theoriesof valency, according to which sulphur, when quadrivalent, is linkedto other atoms by three co-valencies and one electrovalency, a con-clusion which was foreseen by Werner.21 Here is a further exampleof the general rule, already illustrated in the case of Werner’s theoryof co-ordination, that each new development of the theory of valencyhas been accompanied by and has received its final sanction from thediscovery of a new kind of opticaI activity.22An interesting procedure for the recognition and resolution of anexternally compensated conglomerate of d- and I-forms is described 23by G.T. Morgan, W. J.Hickinbottom, and T. V. Barker in their10 J., 1926, 2079; A., 1031.z1 “ Lehrbuch der Stereochemie,” 1904, p. 317.21 T. M. Lowry, Natuse (Suppt.), May, 1926, p. 40.83 P w . Roy. SOC., 1926, [ A ] , 110, 602; A., 503108 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.paper on the stereoisomeric py-diamino-n-butanes. Their method,which may be applied to dl substances having definite meltingpoints, has been successfully used for the recognition of +racernoidsand racemoids.The Resolution of Simple Types of Carbon Compounds.Some interesting resolutions of compounds containing only oneor two carbon atoms have recently been demonstrated. It willbe recalled that chloroiodomethanesulphonic acid (I) is relativelyoptically stable (Pope and Read), whereas fluorochlorobromoacetic? Bryo& ?rbl( Br) c1(IV.) H-C-SO,H H-Y--CO,H (V.1acid (11) becomes racemised immediately on liberation from its activealkaloidal salts (Swarts).It has now been shown 24 by J. Readand A. M. McMath that chlorobromomethanesulphonic acid (111) isat the same time more active and less optically stable than the corre-sponding acid (I) in which iodine replaces the bromine atom. Thebromo-acid (111) was resolved by the use of active hydroxyhydrind-amine, the resolution being accompanied, in acetone solution, bythe deposition of the crystalline I-A, I-B salt (when the 1-base wasused), followed by that of crystals of the &-A, I-B salt. The lattersalt was progressively transformed, by further crystallisation fromacetone, into the 1-A, 1-B salt, thus exhibiting a behaviour similar tothat observed by Pope and Peachey25 during the resolution ofmethylethylpropylstannonium iodide by means of d-camphor-x-sulphonic acid.The resolution of chloro- and bromo-sulphoaceticacids (IV), by Backer, Burgers, and Mook,,O and subsequently (inthe case of the chloro-acid) by Read and McMathF7 and of chloro-bromoacetic acid (V) by the latter authors,2s affords further instancesof optical activity amongst simple types of compounds.The period under review has seen the disappearance for allpractical purposes of the Kaufler formula, in accordance withwhich the rings in benzidine and other derivatives of diphenyl, anda4 J., 1925, 127, 1572; A , , 1925, i, 1126.* 5 P., 1900, 16, 42, 116.26 H.J. Backer and W. G. Burgers, J., 1925, 127, 233; A., 1926, i, 359;PTOC. K . Akad. Wetensch. Amate~dam, 1925, 28, 64; A., 1926, i, 631; IF. J.Backer a d H. W. Mook, ibid., p. 05; A , , 1925, i, 632.27 J . , 1926, 2192; A,, 1025.28 Ibid., p. 2183; A., 1024ORGANIC CHEMISTRY .-PART I. 109even in naphthalene and fluorene, were regarded as situated ininclined planes (see p. 120). There remains, however, the un-doubted resolvability of certain ortho-substituted diphenic acids ;and this can only be accounted for in a satisfactory manner byassuming that the rings, while co-axial, are not co-planar. Thishypothesis, unlike that of Kaufler, accords with the stereochemistryof the Kekulk benzene ring, in which the six bonds to hydrogen orto substituent atoms are situated in the plane of the ring.Pope and Mann have shown 38 that apy-triaminopropane,CH,(NH,)~CH(NH,)~CH,(NH,), is capable of forming co-ordinationcompounds with cobalt and rhodium in which the triamine occupiesthree co-ordination positions. The cobalt salt is represented bythe formula [Co ptn,]CI,, where " ptn " denotes the triaminopropanemolecule.It will be seen that ptn replaces 3NH3 in hexammino-cobaltic chloride, [Co(NH3),]C13, the molecule of the triamine beingbent a t an angle of 60" about the central carbon atom, so that theorganic chain is wrapped about three corners of the octahedron.Of three possible arrangements of this kind the authors consider theirresolvable formto be the most probdble (the thick lines represent the ptn molecule) ;but apparently a labile resolvable modification has also a transientexistence, since the authors have detected fugitive optical activityin the chloride.G.T. Morgan and J. D. M. Smith report 39 that Combes's ethylene-diaminobisacetylacetone is capable of occupying four co-ordinationpositions around cobalt. The compound thus obtained wasresolvable, and two optically active stereochemical modificationswere isolated.The question as to whether the adsorption of dyes by animaland vegetable fibres is a physical or a chemical process is stillunsettled. Porter and his collaborators recorded that one of thea* Compl. rend., 1924, 178, 2085; Proc. Roy. SOC., 1925, [ A ] , 107, 80;8s J., 1925,127, 2030; A., 1925, i, 1457.40 C.W. Porter and C. T. Hirst, J. Amer. Chem. SOC., 1919, 41, 1264; A.,1919, i, 658; C. W. Porter and H. K. Ihrig, (bid., 1923, 45, 1990; A., 1923,i, 1027.I n this case also the optical activity was fugitive.A , , 1925, i, 373; J., 1926, 2675. Compare also J., 1026, 482, 489110 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.optically active isomerides of a dissymmetric azo-dye waO selectivelyadsorbed by wool and silk, and G. T. Morgan and D. G. Skinnerobtained 41 similar results. These results, however, have not beenconfirmed by the recent work 42 of W. R. Brode and R. Adams.T h e Walden Inversion.An interesting aspect of the Walden inversion is illuminated bya paper 44 from J. Kenyon, H. Phillips, and H. G. Turley, in whichan account is given of the transformation of ethyl l 1 d ".lactate toit0 fully active benzoyl derivative by either of two routes, one ofwhichleads to the" d "- andthe other to the" 1 "-benzoylderivative :JPbO*D* $'PhCO&1 "- I 1 d 2,-Et CH 0 2~>c<o'c*phEt0,C CH3>C<H OCOPh HHere it is possible to decide definitely a t what stage the completeinversion occurs, because atoms of the Same elements are attached tothe dissymmetric carbon atom before and after transformation.The authors trace an analogy in the behaviour of the p-toluene-sulphonoxy-radical and the halogen atom in such reactions of similara-substituted esters, and reach conclusions regarding relative con-figurations which are opposed in some respects to those expressed 45by G.W. Clough as a result of his studies of the effects of temperature,concentration, and the presence of inorganic' salts on the rotatorypowers of related active compounds.Clough's important conclusion, that the naturally occurringamino-acids possess the same relative configurations (loc. cit.,p. 539)) is now confirmed,46 and is extended to include the simpleralkaloids.A. RlcKenzie, R. Roger and G. 0. Wills have observed 47 thatwhen I-p-amino-cm-diphenyl-n-propyl alcohol (I) is treated withnitrous acid, it is changed into the highly active d-ketone (111),the asymmetric carbon atom (asterisk) retaining its activity, even4 1 J., 1925,127, 1731; d., 1928, i, 1191.42 J. Amer. C"he7n. Soc., 1926, 48, 2193, 2202; A,, 1031.44 J., 1925, 127, 399; compare also H.Phillips, J., 1923, 123, 44.4 6 J., 1918, 113, 526; compere also J . , 1926, 1674.46 P. Karrer, K. Escher, and R. Widmer, Helv. Chim. Acta, 1926, 0, 301;A., 505.J., 1926, 779; A,, 610ORGANIC CHEMISTRY .--PART I. 111although in the intermediate stage (11) it is associated with onlythree groups. It is not known whether a Walden inversion accom-panies the change. The authors offer the tentative suggestion thatthe asymmetry is temporarily retained owing to the presence of anelectric charge on the carbon atom, although they leave undefinedthe nature and origin of the charge. As they mention, a similarbut more definite hypothesis has already been advanced48 by E.Biilmann in connexion with the action of silver ions upon a-bromo-propionic acid, and more recently B.Holmberg has utilised thosame conception in connexion with the changes undergone bychlorosuccinamic acid. This hypothesis of dissymmetric carbonassociated with three dissimilar radicals and a positive charge isparalleled by that advanced by Kenyon, Phillips, and Turley forthe active sulpho~ides,~~ and is in accordance both with the con-ceptions of Werner and with Baeyer’s hypothesis of carboniumsalts. In the case under discussion, it would seem possible to regardthe unsaturated carbon atom (formula 11) as carrying a positivecharge, the neighbouring unsaturated oxygen carrying a negativecharge, these charges resulting from the ionisation of a ca,rbon tooxygen linking in the intermediate oxide :If then the change to (111) occurred by the migration of a phenylradical carrying an electron (Le.of a phenyl anion), the chargeswould automatically disappear during the transformation, as, infact, they do.Optically active ketones of the foregoing type are very readilyracemised by a trace of alcoholic alkali, and McKenzie, Roger, andWills suggest that loss of activity is brought about by enolisationafter formation of an additive complex with potassium ethoxide,the tendency towards enolisation being practically nil in the ketonealone.48 Annalen, 1912, 388, 330; A., 1912, i, 420.60 LOC. cit.Ber., 1926, 59, 1569; A,, 937112 ANNUAL REPORTS ON THE PROGRESS OF CHENISTBY.I n continuation of the work of Senter upon the influence of thesolvent in displacements involving the optically active carbon atom,it has been found 51 that the bromo-acid produced by the action ofhydrogen bromide upon a given active p-hydroxy-p-phenylpropionicacid in various solvents has always the same sign; and that thesame is true of the conversion of the active p-bromo-acid into thep-hydroxy-amide by means of ammonia in various solvents.Thephenomenon of solvent inversion has, therefore, been demonstratedso far only in the case of phenylhalogenoacetic acids.W. N. HAWORTH.PART 11. HOMOCYCLIC DIVISION.Large Carbon Rings.INVESTIOATIONS of outstanding interest have been publishedduring the year by Ruzicka and his 'collaborators, who have pre-pared a series of homologous ring ketones, (CH,),,>CO, extendingto the ketone with a ring of 18 carbon atoms.Since no pde mono-cyclic compound having a carbon ring of more than 8 atoms haspreviously been obtained, this work constitutes a most notableadvance in our knowledge of homocyclic types.The preparation of ring ketones by the distillation of the calciumsalts of the normal-chain dicarboxylic acids has in the past beenlimited to cyclopentanone, cyclohexanone and cycloheptanone(suberonc), which can be obtained in upwards of 30% yields fromadipic, pimelic, and suberic acids, respectively. H. Mayer andG. K. H. Derlon 1 believed that they had prepared cyclooctanonefrom calcium azelate, but it is now clear that their product con-tained cyclohexanone, methyl heptyl ketone, and an unidentifiedketone, in addition to cyclooctanone.The first satisfactory synthesisof a cyclooctane derivative was carried out by 0. Wallacl~,~ whoprepared cyclooctanone by oxidation of the crude cyclooctanolobtained by the action of nitrous acid on suberylmethylamine(Demjanov's reaction 4). This work, together with that of Ciamicianand Silber and of Willstatter on the degradation of the alkaloidG. Senter and A. M. Ward, J., 1924,125, 2137; A , , 1925, i, 31; J., 1926,l Annalen, 1893, 275, 363; A . , 1893, i, 557; Bev., 1898, 31, 1957; A . ,* L. Ruzicka and W. Brugger, Helv. Chim. Acta, 1926, 9, 339; A,, 811.127, 1847; A., 1925, i, 1128.1898, i, 638.Annales, 1907, 353, 328; A . , 1907, i, 602.9. J. Demjanov, J. Rusa. Phys. C'kem. Soc., 1904, 36, 166; A ., 1904,i, 410ORGANIC CHEMISTRY .-PART It. 1134-pelletierine, represents the approximate sum of our previousknowledge of cyclooctane and its derivatives. Ruzicka and Bruggerhave now shown that 6% of pure cyclooctanone can be obtainedfrom calcium azelate, and 10% from cerium azelate; their maindiscovery, however, is the fact that the use of the thorium saltincreases the yield to 25%, thus rendering cyclooctanone for thefirst time a readily accessible material for the preparation of cyclo-octane derivatives. The identified by-products which arise duringthe distillations of these salts are those which would be formed ifa part of the azelate were to undergo oxidative fission to a pimelateand an acetate, whilst another part lost a carboxyl group as carbondioxide :CH,*CH,*CH,*CO,H CH,GH,*CH,-COhH2GH2*CH2-CH2*C02H - dH2*CH2*CH2dH,,-*--\ (cyclooctanone, m.p. 28') + co, $!H2*CH2'CH2mC02H + CH,.CO,H FH,*CH,*CH,.CO,HCH,.CH,-CO,H CH2*CH,*CH,*CH,IFH,.CH,*CH, CH,*CH,*CH,*CO*CH,CH,*CH,dO hH,*CH,*CH,*CH,As R. Willst,&tter and T. Kametaka suspected,* the ketoneobtained by distillation of calcium sebacate is a mixture,8 butpure cyclononanone may be obtained by distilling thorium sebacate.The yield is only 1.5% and the by-products are suberone, methyloctyl ketone, and an unidentified higher ketone, corresponding,therefore, with the by-products accompanying cyclooctanone fromthorium azelate :(;'H,*CH2*CH,>C0 CH,.CH,*CH,*CO*CH, FH,CH,*CH,*CH,>COCH,.CHz*CH, bH,.CH,*CH,*CH,.CH, CH,*CH,*CH,*CH,(cyclononanone, m.p. 0')The reaction is therefore unsatisfactory as a starting point for thepreparation of cyclononane derivatives, but Ruzicka and Brugger 10have applied a modification of the Demjanov process to cycZooctanone5 LOC. cit.6 Ber., 1907, 40, 3876; A . , 1907, i, 936. Compare R. Willstiitter end7 N. Zelinsky, ibid., p. 3277; A . , 1907, i, 780.8 L. Ruzicka and W. Brugger, Helv. CAim. Acta, 1926, g, 389; A., 726.9 L O C . eit.Bruce, ibid., p. 3980; A . , 1907, i, 1018.lo Ibid., p. 399; A,, 727114 ANNUAL REPORTS ON THE PROGRESS OF OHEMISTRY.with results which appear to form the basis of a feasibIe preparativemethod :The cyclononanol is easily separated and can be smoothly oxidisedto the cyclic ketone.The higher ketones,ll from C,, to CIS, were obtained by vacuumdistillation of the thorium salts of the long normal-chain aw-di-carboxylio acids.12 The ketones were separated from the crucicdistillates in the form of semicarbazones, from which they wereafterwards regenerated, and their structures were established byoxidation to the corresponding polymethylene-am-dicarboxylicacids. The yields of the ketones passed through a minimum(0.1--0.2%) a t cyclodecanone and thereafter slowly rose with theincreasing number of carbon atoms.The ketones from cyclododecanone to cycZooctadecanone aresolids a t the ordinary temperature :No.of Catomsinring ... 10 11 12 13 14 15 16 17 18M.p. of cyclic ketone ... ? ? 59" 32" 52' 63" 56' 63" 71'As the molecular weight of the ketone increases, its odour changes;cyclodecanone, cycloundecanone and cyclododecanone have theodour of camphor ; the odour of cycloterdecanone faintly resemblesthat of cedarwood, and in the ascending members of the series(C14 to C18) the odour of cedarwood becomes increasingIy apparentwhen the vapours are in high concentration.At greater dilutions,however, the predominant odour of cyclotetradecanone and especiallyof cyclopentadecanone is that of musk, whilst the odours of thehighest members, cyclohexa-, cyclohepta-, and cycloocta-decanone,under similar conditions, resemble that of civet.cyctoPentadeoanone is now being manufactured, under thetrade name " exaltone," as an artificial substitute for musk.Stability of Large Carbon Rings.-A striking discovery, which is,however, in complete agreement with the Sachse-Mob theory of11 L.Ruzicks, M. Stoll, and H. Schinz, Helw. Chim. Acta, 1920, 9, 249;A., 616.In This vol., p. 101ORUANIC CHEMISTRY .-PART II. 115strainless rings,la is that these large rings, once formed, are just asstable as 5- and 6-membered rings.14 The cyclic ketones fromsuberone to cyclooctadecanone underwent no change (except asmall amount of charring and polymerisation) when heated withconcentrated hydrochloric acid at 180-200" ; certainly degradationto smaller molecules did not occur, and there was no evidence ofany ring-fission or isomeric change. cycloHeptadecanone waspassed over thoria a t 400420" and recovered unaltered. cycle-Pentadecane and cycloheptadecane, two well-defined, crystallinehydrocarbons, m.p.'s 61' and 65", which were prepared by reductionof the semicarbazones of the corresponding ring ketones, wererecovered completely unchanged after heating with phosphoms andfuming hydriodic acid a t 250". It is pointed out l5 that accordingto the elementary strain theory a 7-ring is comparable with a 4-ringand a 17-ring with a 3-ring.No. of carbon atoms in ring ... 3 4 7 17Angular distortion (Baeyer) ... +24" 44' SOo 44' -9" 33' -224' 41'But the corresponding 3- and 4-membered ring compounds wouldnot, of course, survive such treatment.Fomzatiolt of Large Carbon Rings.-If, however, we consider,not stability, but tendency to formation, the difference between thesmall and the large rings is in the opposite seme.In contrast tothe numerous methods by which 3- and 4-membered carbon ringsmay be prepared, the rings containing from 10 t o 18 carbon atomsare accessible by only one method, and in small yield. The yieldsobtained by the distillation of thorium and calcium salts appeart o show a maximum a t cyclohexanone :CIlutaric ........................ 0 0 4Adipic ........................ 16 45 6Pimelic ........................ 70 40-50 6Suberic ........................ ti0 36 7Azelaic ........................ 20 6 8Sebacic ........................ 1.5 <1 9Data such as these may be partly correIated by assuming 16 thatthe formation of a ring depends on the product of two factors. One,connected with the distance between the two ends of a chain,will favour the production of small rings ; the extreme case of thelS Ann.Report, 1924, 21, 92. Compare J. 'VV. Baker, J., 1926, 127, 1678;W. A. Wightman, ibid., p. 1421; J., 1926, 2641; F. W. Kay and hi. Stuart,ibid., p. 3038; W. Huckel, Annalen, 1926, 451, 109; W. Huckel and H.Friedrich, ibid., p. 132.1' L. Ruzicka, W. Bruggsr, M. Pfeiffer, H. Schinz, and M. Stoll, Helv.China. Acto, 1926, 9, 499; A., 727.Acid. Th-salt (%). Ca-salt (yo). C-atoms in ring.Idem, ibid. Idern, aid116 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.operation of this factor would be represented by the formation of adouble bond. The second factor will depend on the intrinsicstability of the ring, and will favour the production of strainlessrings.The idea may be expressed graphically (Fig. 1) : curve arepresents the " distance factor," and it falls continuously withincreasing length of the chain which is to be closed ; curve Z, depictsthe ('strain factor," rising to a point between C, and C6 and there-after remaining constant, since the higher rings are strainless.Apart from these main features, the curves are, of course, arbitrary,and the resultant curve, c, represents some kind of mean betweenthem, with its minimum at C, and its maximum between C, and c6,corresponding with the observed data.FIG. 1 .Number of carbon atoms.Physical Properties of Large Rings.-The increment in mqlecularvolume a t 20" of the normal aliphatic hydrocarbons, for eachadded CH,-group, is 16 units and is constant from C, to C,, ; theincrement for the alioyclic hydrocarbons is not constant, but risesfrom about 13 to 16 over the same range.Again, the incrementfor the open-chain ketones is approximately 16g units and is sensiblyconstant; that for the cyclic ketones, on the other hand, risesbetween C, and C,, from 14 to IS&. The following table illustratesthese contrasts : 17l7 L. Ruzicka, W. Brugger, M. Pfeiffer, H. Schinz, and M. Stoll, Helv.Chim. Ada, 1926, Q, 499; A,, 727ORGANIC CHEMISTRY.-PART II. 117Hydrocarbons d ( X / d ) . Ketones d ( M / d ) .7 r , , I- -Aliphatic. Cyclic4 Aliphatic. Cyclic,No. ofC-atoms.4667891011121314151617181915.016-016.515.416.116.216.015.916.715.716.915.916.516.2 -12.6 16.014.0 17.313.0 16.813.2 16.815.717.2Mean 16.516.3 \Mean16.0J15.3MeanMean16.516.2--13.714.814.513.614.9Mean15.6Mean15.616.616.616.7 -That the increments for the cyclic series should, in each case,from about 4, upwards, be within a unit of the figure characteristicof the corresponding aliphatic homologues, agrees, of course, withthe hypothesis of multiplanar configurations ; for these large ringswill be wholly collapsed, and so crumpled that the volume requiredby an added CH,-group will be the same as if it were added to asimilarly crumpled aliphatic chain.In the intermediate ringafrom C, to Cl0, the collapse is probably only partial, in the sensethat a certain amount of space inside the ring, and dependent onthe existence of the ring, becomes a more or less permanent additionto the volume occupied by the molecule.In the rings below C ,distortion during thermal agitation is largely eliminated ; the mole-cule now has a characteristic shape and the internal space nowrepresents a quite d e h i t e addition to the volume occupied, part ofwhich is assigned to each of the constituent methylene groups.Thus as we descend the series the volume of the molecule increasesrelatively (Lee, decreases more slowly than it otherwise would)and the decrements become smaller.The volumecontribution of CH, in a hydrocarbon (open-chain) is known tobe 16.1 units. The molecular volumes of the cycloparaffins, dividedin each case by the number of CH, groups in the ring, are asfollows :No.ofCH,groups(lz) .. . 4 6 6 7 8 . . . 15 17( M / d ) / n . . . . . . . 20.4 18.8 18.0 17.3 1 6 . 8 . . . 16.1 16.1The numbers for the smaller rings ( P 8 ) obviously represent thevolume occupied by the CH, group, plus a share of the internalThe matter may be illustrated in another way118 ANNUAL REPORTS ON THE PROGRESS OF OFEMISTRY.space: in the 15- and 17-membered rings there is no internalspace and the normal value obtains.Occurrence of Large Rings in hTature : Muscone and Civetme.-Until this year no monocyclic 18 compound containing a ring ofmore than six carbon atoms had been proved to occur in the animalor the vegetable kingdom.lQ It is now clear, however, that musconefrom the musk-deer contains a ring of fifteen carbon atoms,20whilst civetone from the civet cat contains a 17-membered carbonring.21Muscone, a liquid ketone, C,,H,,O (semicarbaxone, m.p. 134O),was isolated from musk by H. Walbaum.22 It is saturated and hencemonocyclic, and its optical activity shows that it must contain anasymmetric carbon atom. Since racemisation does not occur onconversion into the sodio-derivative of the enol, the centre ofasymmetry cannot be a tertiary carbon adjacent to the ketonegroup. Oxidation yields decane-aK-dicarboxyh acid, from which itfollows that an uninterrupted chain of a t least 10 methylene groupsmust be present. Several 13-, 14- and 15-ring formula are con-sistent with these conclusions, but the identity of the d o u r withthat of certain methylcyclopentadecanones, which were prepared bydistillation of the appropriate thorium salts, was taken as indicatinga 15-ring structure, and the surmise was c o n m e d by reducingmuscone to methyIcycZopentadecane, CH,*CH<(CH,),4, which wasalso prepared from one of the synthetic ring ketones.It remainedto determine the relative positions of the methyl and ketone groups,the possibilities being represented by p- y-, and 8.methylcyclo-pentadecanone :HMe-CH2.CH2- H2 H2.CHMe-CHz-FH2 H,*CH,*CHMe* H280(b) (muscone)( 8 H2)lO co ( 8 Hzho( Y )Final identification was rendered diEcult by the fact that musconeand many of its more closeIy related derivatives are optically active.The y-methyl formula was excluded as improbable, because them. p.of the semicarbazone of a synthetic (inactive) specimen ofthis ketone was lowered by admixture with muscone semicarbazone ;and a decision in favour of the p-methyl formula was made on theground that the methyltridecane-au-dicarboxylic acids, obtained by16 The qualification is intended to exclude bicyclic heterocyclio compoundswith a single hom~cyclic ring, like tropine and $-pelletierine, and also bridgedhomocyclic compounds such as the carenes.80 8 H 2 h(8)19 But cycloheptane occura in Caucasian petroleum.10 L. Ruzicka, Helu. China. Aota, 1926, 0, 716; A,, 1142.11 Idem, ibid., p. 230; A., 614.33 J . pr. Chern., 1906, 73, 488; A., 1906, i, 696ORGAN10 CHEMISTRY .-PART IT.119oxidation of muscone and its benzylidene derivative, althoughoptically active, agreed much more closely in their properties withthe synthetic a- and p-methyl acids, CO,HCUCMe~(CH,),,.CO,H andC0,H~CH,.CHMe.(CH2)ll*C02H, to be expected from a ketonehaving the 9-methyl formula, than with the isomeric y- and &methylacids, C0,H~(CH,)2*CHMe.(CH~)lo~C0,H andCO,H.(CH,),.CHMe*(CH,),~CO,H,corresponding with the 8-methyl ketone structure.23 This proofof the constitution is admittedly not quite complete.Civetone, an unsaturated ketone (m. p. 31") having the compositionC1,H3,0, was obtained from civet by Sack.24 It contains one doublelinking and, therefore, a single ring, and the character of the ring isrevealed by the fact that the dihydro-derivative, obtained bycatalytic reduction, is identical with synthetic cycloheptadecanone(m. p.63"). The position of the double linking follows from theobservation that azelaic acid, but no higher polymethylene-aw-dicarboxylic acid, is formed on oxidation.This determines the formula, and it is interesting from the bio-logical point of view t o compare it with that of oleic acid and tospeculate on the possibility of their biochemical interconversion.21fp(CH,),.CH, + gH.(CHd 7)COCH*(CH,)7C0,H CH*(CH2)7(oleic acid) (civetone)Stereochentistry. The Diphenyl Problem.A remarkable outcome of work published during the year is theproof that a coincidence of errors was directly responsible forChristie and Kenner's fundamental discovery (1922) that certainderivatives of diphenic acid are capable of optical reiolution.Forthe past 4 years, however, the same errors have obscured the wholeappearance of the stereochemical problem thus opened. Kow,with their rectification, effected in a series of papers published inrapid succession, the whole problem enters upon a new phase.*J L. Ruzicka, Hdv. Chim. Ada, 1926, 9, 1008. '' E. Sack, Chem. Ctg., 1915, 39, 538; A., 1915, i, 888120 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The reported existence of the ring compounds of benzidine,(1)-(VI), which had been described by a number of independentw0rkers,~5 led F. Kaufler,26 in 1907, to propose his folded structure(VII) for the diphenyl system. J. C. Gain and his co-workers(1912-14)) believing that they had established the existence oftwo o-dinitrobenzidines and two pairs of m-dinitrotolidinea 27(VIII-XIII), adopted the Kauflor formula as an explanation ofthese conventionally inexplicable isomerides, and supported theirconclusions by the preparation of further " Kaufler compounds(types XIV and XV) from bonzidine and tolidine by condensationwith the a-diketones glyoxal and benzi1.28IC>NH2X,X ,C>"zx (9%X Mei b N H 2Me[X = NO,](XII.) (XIII.)Independently of these investigations, J.Schmidt and A. Klimpfhad recorded experiments 29 which appeared definitely to orient analready known dinitrodiphenic acid (prepared from a dinitrationproduct of phenanthraquinone 30) as the 6 : 6'-derivative (XVI).When, therefore, J.Kenner and W. V. St~bbings~lobtained a different* l W. Miohler and A. Zimmermenn, Ber., 1881,14, 2178; A . , 1882, i, 182;J. Borodin, Jahresb., 1860, 366; 2. Chem. Pharm., 1860, 641; J. Strekosch,Ber., 1872, 5, 240; G. Koller, Ber., 1904, 37, 2882; A., 1904, i, 778; H. Schiffand A. Vanni, Annalen, 1890, 258, 363; A . , 1890, 1297; J. Barzilowski, J.* 6 Annalen, 1907, 351, 161; A., 1907, i, 307; Ber., 1907, 40, 3250; A . ,RWs. Phy8. Chern. S O C . , 1891, 23, 69; A., 1892, 854.1907, i, 794.J . , 1912, 99, 2298; 1914, 103, 1442.g8 I b d , 1914, p. 1437.pB Ber., 1903, 36, 3745; A . , 1904, i, 71,aa G. Schulze, Annalen, 1880, 203, 95; A., 1880, 814.31 J., 1921, 119, 693ORGANIO CHEMISTRY .--PART II. 1216 : 6'-dinitrodiphenic acid (from 2-iodo-3-nitrobenzoic acid andcopper powder) they naturally concluded that they were possiblydealing with a pair of '' Kaufler stereoisomerides " (XVII andXVIII).The allocation of configurations presented no difficulty,for the new compound on reduction gave the dilactam (XIX),whilst the old one had already been formed from a phenanthraquinoneand converted (by Schmidt and Kiimpf) into carbazole.32 Itfollowed that the new acid might be capable of optical resolution :(XVI.) (XVII. c;S, non- (XVIII; t~ana, (XIX.)resolvable. ) resolvable .)and it was.=Since then, the following compounds (XX-XXIV) have beenresolved, though none has been obtained in more than one in-active (racemic) modification :(XXIII.) 8 7 gozH (XXIV.) 88NO CO,HL O C .cit.Idem, a i d .Idem, J . , 1923, 125, 779.G. H. Christie, C. W. James, and J. Kenner, ibid., p. 1948. *' G . H. Christie, A. Holderness, and J. Kenner, J., 1926, 671: A., 518.F. Bell and J. Kenyon, Chem. and Ind., 1926, 45, 864; compare G. H.33 G. H. Christie and J. Kenner, J., 1922, 121, 614.Christie, i b i d . , p. 934122 ANNUAL REPORTS ON THE PROUEESS OB OHEMISTRY.In addition, the following have been investigated with the objectof resolving them, but have so far resisted resolution (XXV-XXIX) :I n 1920, C. V. Ferrivs and E. E. Turner 41 investigated Cain’asupposed ring compounds (types XIV and XV), and were unablcto confirm the conclusions which had been drawn with regard tothem. This year, Turner and his collaborators have systematicallyoverhauled the whole of the evidence on which Kaufler based hisspace formula, with the result that no part of it survives.42 Thecarbonyl compound (I) contains a free amino-group and is probably(IA) ; the thiocarbonyl compound (11) is certainly (IIA) ; the oxalylcompound (111) contains a free amino-group ; the phthalyl corn-pound (IV) is really (IVA) ; the phthalyldiethyl derivative is nota chemical individual ; the nitrobenzylidene compound (VI) has thestructure (VIA).43 In addition, Cain’s condensation product frombenzidine and benzil is really ( X I V A ) , ~ whilst the glyoxal condensa-tion products, which also were formulated as ring compounds, arehard, brown resins of unknown molecular weight.[NQ(C6H4),.NH],CO N~*(C,H,),.N:C:S NHz.(C6H*),.N<~~>c6H4P *) (Ira.) (IVA.)Next, it is proved45 that the most fully investigated of Gasin’spairs of isomerides, na.mely, the two dinitrobenzidines (VIII andIX), are, in fact, structurally distinct (XXX and XXXI).Theobservation that they give different tetra-amines on reduction 46z9 F. Bell and J. Kenyon, lac. cit. ; J., 1928, 2705; A.. 1241; ibid., p. 3044.C. H. Christie, loc. cit. ‘l J., 1920, 117, 1140.R. J. W. Le FBvre and E. E. Turner, J., 1926, 2476; A., 1131.H. G. Dennett and E. E. Tuner, 8id.. p. 478; A., 391.‘4 R. J. W. La FBvre and E. E. Turner, bc. cit.4 6 Idem, a%&, p. 1 7 K O ; A, 946.0. L. Brctdy and G. P. MaHugh, J., 1923,123, 2047OBUANIU OHEMISTRY .-PART 11. 123is therefore explicable, but the statement that these yield identicaldiquinoxalines is, by implication, an error.Independently, it isalso shown 47 that Schmidt and Kampf’s proof of the constitution ofthe long-known dinitrodiphenic acid is without foundation, the pairof compounds (XVII and XVIII) handled by Kenner and Stubbingsbeing actually position isomerides (XXXII and XXXIII) ; and thatthe individual (XXXIII) previously regarded as probably belongingto the cis-, non-resolvable class, can, in fact, be resolved. The twopairs of supposedly stereoisomeric dinitrotolidines (X-XIII) stillremain unchallenged (except by implication), but the indirectevidence is very strong that the recorded observations on thesecompounds are to be accounted for in some other way than thatchosen by their discoverers.NO2 NO, NO,NH2&k2 N H , m 2(XXX.) (XXXI.)Thus, not only the phenomenon which Kaufler’s space-formulawas invented to explain, but also that which it was afterwardsresuscitated to interpret, do not exist; and the formula itself haslost castej8 The sole remaining relevant fact is that six sub-stituted diphenic acids have been resolved, and it is thus possible toview the matter afresh.Attempts are being made to do so.E. E. Turner and R. J. W.Le FBvre49 attribute the possibility of optical resolution to arepulsion between ortho-substituents which tends t o push theplanes of the rings apart (by rotation about the internuclear bond),whilst the attraction between the ortho-carbon atoms tends to limitthe angular separation ; the ‘ I repulsion ’) is regarded as eitherelectrical or spatial in origin :v (enantiomorphoue forms)F.Bell and J. Kenyon suggest4 7 GI.. H. Chriatie, A. Holderness, and J. Kenner, Zoo. cit.48 Compare R. Kuhn apd F. Zumstein, Rep.., 1926, 58, 488; A., 613.that, owing either to theirelectrical character or to their size, two ortho-groups, (X) and (Y),Chem. and Ind,, 1926, 45, 831. ‘O Ibi& p+ 864; J., 1926, 3046124 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.act as obstacles to the passage of an ortho-group (Z) on the othernucleus, thus preventing interconversion of the optical antipodes :X7 (enmtiomorphous forms)W. H. Mills 51 holds a similar view, and in addition points outthat, if it is legitimate to assume a considerable degree of mole.cular rigidity, spatial considerations alone are able to provide anFIG.2.1* Reproduced by w permission from Chemiatry and Industry.explanation for all the optically active diphenyl derivatives hithertorecorded. Thus in 6-chlorodiphenic acid (Fig. 2) the carboxylgroup attached to the lower nucleus can pass neither the chlorineatom (large circle) nor the other carboxyl group, and hence isconfined to a limited region in front of the plane of the upper ring ;in the enantiomorph, similarly depicted, the corresponding carboxylgroup would be always behind the: plane of the upper ring : 52Actually, 6-chlorodiphenic acid has not yet been investigated, but61 C h m . and Ind., 1926,46, 883, 906.6 1 The nuclear hydrogen atoms are omitted from the figure, as i t is assumedthat they would be too small to limit the mutual relative rotations of thephenyl rings by the mechanism discussedORQANIC CHEMISTRY .-PART II.125the argument applies to all the diphenic acids which have hithertobeen obtained in optically active modifications (XVI and XX-XXIV). It should be stated that molecular dissymmetry originat-ing in co-axial but non-coplanar nuclei was one of the possibilitiesoriginally envisaged by Christie and Kenner ; but the “ obstacletheory ” of the mechanism whereby the enantiomorphous formsmaintain their individuality appears to be B definite advance,because, not only does it afford a satisfying explanation of all therecorded positive observations, but it also shows why the attemptedresolutions of other diphenyl derivatives (XXV-XXIX) wereunsuccessful : for in each of these a t least one of the three ortho-groups which, according to the hypothesis, are required to producestable enantiomorphs is absent from the molecule.On the assumption that the ortho-substituents are such as willform effective obstacles to the relative rotation of the phenyl nuclei,resolvable diphenyl derivatives should conform t o the typesA X A Xwhere A and B are different from each other, and X and Y also aredifferent from each other, although neither is otherwise precludedfrom identity with A or B.The case is, in fact, comparable withthat of allene derivatives,;>c=c=c<y, Xthe essential condition being the indirect attachment to the centreof dissymmetry of two pairs of unlike groups by en arrangementwhich prevents their occupying a common plane ; but, in diphenylderivatives, the centre of dissymmetry resides, not in an atom, butin B bond.It remains to be seen whether small, but highly polar,groups (e.g., fluorine or ionised hydroxyl in 6 : 6’-difluorodiphenicacid or an alkaline solution of 6 : 6’dhydroxydiphenic acid), whichfrom the purely spatial point of view would hardly be expected toconstitute effective obstacles, are also capable of imparting potentialoptical activity to the molecule.It may be added that certain reactions which caused Kenner andStubbings 55 to postulate cia-trans inversion-for example, theformation of a hydrazide from the same dinitrodiphenic acid whichwhen reduced yields the dilactam :E.* Loc, cit.Compare also E. E. Turner and R. J. W. Le FBvre, Zoo. cG?126 ANNUAL REPORTS ON THE PROQRESS OB OHEMISTRY.-1 NH-COare readily explained on the new theory ; because an ortho-groupattached to one phenyl nucleus will, in its mean position, beapproximately equidistant from the two ortho-positions of the othernucleus, and the formation of a ring in either direction should bepossible.Other Xtereochemical Problems.-Definite advances have beenmade during the year in other stereochemical problems, but forthe most part along lines already laid domi by past work.The optical resolution of sulphinic esters, reported last year," ha8been followed up by the resolution of the two sulphoxides (XXXIV)and (XXXV) 55 and the aulphilimine (XXXVI),s6Every case of this kind naturally strengthens the evidence of thestability of the sulphonium octet ; but the question why the latentfourth valency of sulphonium sulphur should so rigidly maintain itsplace in the tetrahedral arrangement, whilst the correspondinglatent valency in neutral tervalent nitrogen does not appear to doso, remains for the present unanswered (except for the suggestionthat it has something to do with the positive charge).Bradg and Bishop's experiment, reported last year,57 on kooxazolering closure with aromatic aldoximes, has now been paralleledfor ketoximes by Meisenheimer and his collaborators with corre-sponding results,5* which therefore favour the general proposal t o64 Ann.Report, 1925, 22, 111.65 P. W. B. Harrison, J. Kenyon, and H. Phillips, J., 1926, 2079; A,,60 S, G. Clarke, J. Kenyon, and H. Phillips, J., 1927, 188.57 Ann. RepoH, 1925, 22, 107.m J. Meisenheher, P. Zimmermann, and M. von Kummer, Annalen, 1926,1030.448, 205; A,, 406ORGAKTU CEEMISTEY.-PABT II. 127invert oxime configurations. A special feature of the year's workon this subject is, however, the fact that it has been attacked fromthe physical side. N. V. Sidgwick has shown 59 that the solubilityand volatility of the enolic forms of p-diketones and @-ketonic esterscan be accounted for by the structure (XXXVII), where the arrowrepresents a co-ordinate link formed by two electrons from theoxygen atom. T.W. J. Taylor and E. K. Ewbank 6o now pointout that the same theory, applied to the isomeric monoximes ofa-dilretones, satisfactorily explains, not only their physical properties,but also their chemical differences; for the isomeride which is themore volatile and soluble in non-polar solvents is that which showsleast carbonyl reactivity. This view, of course, implies definitestereochemical con3gurations for each pair of oximes, and in thecase of benzil the configurations so arrived at (XXXVIII andXXXIX) are identical with those deduced by Meisenheimer fromthe oxidative fission of triphenylisooxazole : 61PhG-GPh PhG- P h-HtO H0.N 0 N. OHtOThe fact that only u-bendmonoxime gives metallic co-ordinationcompounds with iron, cobalt, and copper is accounted for by thehypothesis that an attack by the metal cation on the carbonyloxygen atom constitutes the f i s t step in the formation of thesecompounds.On the whole, the balance of evidence seem8 atpresent to be more heavily loaded on the side of the inversion ofthe customary oxime configurations, but 0. L. Brady and R. F.Goldstein 62 record observations showing that aromatic cc-aldoximes(Le., the isomerides which less readily yield nitriles) are strongeracids than the isomeric p-aldoximes, and that is a weight in the otherpan.Taylor and Ewbank apply their considerations t o the alliedproblem of the configuration of hydrazones, with very satisfactoryresults. Thus of the two hydrazones of glyoxylic ester,63 one is aliquid and is more volatile and less soluble in water than the other,and the liquid isomeride has the normal molecular weight in benzene,whilst the other is a solid and is associated in solution.The con-figurations (XL) and (XLI) follow, and accord well with the factthat, whereas the liquid form reacts only slowly with phenyl-carbimide and not a t all with diphenylketen, the solid isomeridecombines readily with both these reagents :(XXXIX; 6%) -r(+G- (XXXVII.) (XXXVIII; a-.)6a J., 1925,121, 907.a1 Ann. Report, 1925, 22, 106.4, 228; A., 1921, i, 326.Ibid,, 1926, 2818.li2 J., 1926, 1918; A., 1039.H. Staudinger, L. Hmnmett, and J. Siegwart, H&. Chim Acta. 1921128 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.#*OEt gH+*OEtNH,9N 0GH-N-VHtO(XL; liquid form.)H(XLI; solid form.)Other examples discussed are the camphorquinone hydrazonesinvestigated by M.0. Forster and A. Zimmerli,B4 and in this con-nexion it should be mentioned that the following statement, whichoccurs in last year’s Rep0rt,~5 is misleading: “Pairs of stereo-isomeric hydraaones have frequently been described, but no methodof orientation in which any degree of confidence could be placed haduntil recently been evolved. ” The Reporter had overlooked thefact that in the course of the work referred to above (1910-1911)Forster and Zimmerli had oriented pairs of hydrazones and substi-tuted hydrazones by the method of ring formation which has beenapplied only within comparatively recent years to other pairs ofhydrazones and to the oximes.Further work on the truxillic acida has led to the revision of aformula previously proposed for c-truxillic acid,66 and this, togetherwith a new investigation of y-truxillic acid,67 confirms the allocationof configurations amongst the five truxillic acids given in theAnnual Report for 1924 (p. 95).Optical Activity Dependent on Co-mdinated Beryllium, Copper, a dZiq-An important paper on this subject has just appeared.T.M. Lowry and H. Burgess 68 had observed that beryllium benzoyI.camphor, when dissolved in chloroform or benzene, shows mutarota-tion, which they ascribed to the gradual disappearance of opticalactivity associated with the beryllium atom ; they pointed out thatthis atom would probably act as a centre of dissymmetry in aspiran arrangement such as that represented in Fig.3.W. H. Mills and R. A. Gotts gg have now shown that an inmtivep-diketone, namely benzoylpyruvic acid, C,H,gC~oCH,~COoCO,H,which in itself is devoid of molecular dissymmetry, can acquire iton conversion into its beryllium derivative. Two brucine salts ofthis derivative were prepared, and these, when dissolved in chloro-form, exhibited changes of rotatory power which were substantiallyequal and opposite ; also the diBcult task of removing the aIkaloidwithout destroying the sensitive optical activity associated withthe beryllium atom was accomplished with a large degree of success.64 J., 1910, 97, 2156. Compare J., 1911, 99, 478.B G Ann. Report, 1925, 22, 111.6 6 R. Stoermer, J.Neumaerker, and R. Schmidt, Ber., 1925, 58, 2707;67 R. Stoermer and F. Fretwurst, ibid., p. 2718; A,, 1926, 291.EB J., 1924,1$25,2081.A., 1926, 290.as Ibid., 1926, 3121ORGANIC CHEMISTRY .-PART 11. 129The tetrahedral arrangement thus established for the four oxygenatoms surrounding the beryllium atom (Fig. 3) corresponds with thatdeduced for the crystalline state by Sir W. H. Bragg and G. T.Morgan 'O from their study of basic beryllium acetate :Alkaloidal salts of the analogous copper and zinc derivatives ofbenzoylpyruvic acid were also prepared, and they showed an opticalbehaviour closely similar to that of the beryllium compound ; therecan be no doubt that this is due to a corresponding cause. Sincocopper and zinc ark both capable of forming tho-ordinated deriva-tives in which the groups are almost certainly octahedrally disposed,these observations are of considerable interest because they indicatethat when two of the six co-valencies become latent the remainingfour assume a tetrahedral configuration.It is pointed out that aFIG. 3.similar conclusion must apply to arsenic in view of the opticalresolution of tripyrocatechylarsenic acid, H[As(C,H~O,:)~],~~ andof p-carboxyphenylmethylethylarsine sulphide, R1R,R3AsS.72Orienting Effects in Benzene Substitutions.A considerable amount of attention has recently been devoted tothe study of the mcchanisrn of aromatic substitution. Definiteexperimental and theoretical advances have been made, but a tthe same time it has become increasingly evident that a completelysatisfactory interpretation is still indefinitely remote.I n themeantime, the complexity of the subject seems to render an interimreport desirable.(i) Orienting Effect of Po2e.s.-(The seat of the charge in a complexion may conveniently be termed a '' pole.")The established phenomenon of intramolecular ionisation (e.g.,in semipolar double linkings) and the probable occurrence of bothm Proc. Roy. Soc., 1923, [ A ] , 104, 437; A , , 1924, i, 7.'I1 A. Roeenheim and W. Pleto, Ber., 1925, 58, 2000; A., 1925, i, 1412.7a Ann. Report, 1926, 22, 113.REP.-VOL. XXIII. 130 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.incipient intramolecular ionisation and incipient ionic dissociationin organic molecules render impossiblo a sharp distinction betweenelectrically charged and uncharged atoms.Nevertheless, thoseatoms which carry one or more of the integral charges created by theionic dissociation of a strong electrolyte may be conveniently con-sidered together in regard to their orienting effects, because theseprobably represent the extreme (and therefore most easily appre-hended) examples of phenomena which other atoms are also able tobring about in various lesser degrees according to their severalelectrochemical characters.The orienting influence of a positive pole directlyattached to the nucleus is readily stated : it is exclusively m-direct-ing so far as is known. The main established examples are thebromination of phenyltrimethylammonium bromide,'3 and thenitration of phenyltrimethylamrnonium nitrate,74 of diphenyl-iodinium nitrate,75 triphenylhydroxyphosphonium nitrate,76 tri-phenylantimony dinitn~te,~' triphenylbismuth dir~itrate,'~ anddiphenyl-lead dinitrate.'g In these instances, the observed orientingeffects are substantially identical, despite the fact that the chargedatom ranges in atomic weight and electrochemical character fromnitrogen to lead and from lead to iodine.Further, since in no casehas any 0- or p-isomeride been isolated, it appears that the side-chains present in all these compounds are amongst the strongestm-directing groups known. The inference, that a positive poleattached to the nucleus is m-orienting independently of the natureof the charged atom, has been drawn by D.Vorlknder.80The introduction of successive saturated carbon atoms (e.g.,-CH,- groups) between a positive pole and the nucleus diminishesthe m-orienting effect. Ionised benzylammonium salts are nitratedlargely, but not wholly, in the rn-position; 82, 83 p-phenylethyl-ammonium salts, on nitration, also undergo m-substitution, but to asmaller extent ; and with y-phenylpropylamrnoiium salts theproportion of m-derivative is smaller stilLs4 The steady diminution'3 D. Vorldndor and E. Sicbort, Ber., 1919, 62, 283; A., 1919, i, 310.7 4 I d e m , ?bid.11. Vorlander and K. Buchiner, Bcr., 1925, 68, 1898; A . , 102.5, i, 1133.1,7 6 A. Jlichaelis and H. v. Soden, Annaleia, 1885, 229, 324; A . , 1588, 1134;7 7 G. T. Morgan and F.M. G. Micklethwait, J., 1911, 99, 2286.7 * D. Vorlander and E. Schroedter, Be?., 1925, 58, 1900; A . , 1925, i, 1255.Positive poles.I?. Challenger and J. F. Wilkinson, J., 1024, 125, 2678; A . , 1925, i, 172.D. Vorlhder and E. Spreckels, ibid.D. Vorliinder, ibid., 1919, 52, 262; A., 1919, i, 519.81 €3. Flurscheim and E. L. Holmes, J., 1926, 1562; A., 830.a a H. R. Ing and R. Robinson, ibid., p. 1656; A., 946.8 3 F. R. Goes, C. K. Ingold, and I. S. Wilson, ibid., p. 2440; A,, 1132.F. R. Goes, W. Hadart, and C. K. Ingold, J . , 1927, 250ORGAlPIC OHEMISTRY,-PART 11. 131in the amount of m-substitution with increasing length of thecarbon chain may be illustrated by the following series :Nitration of:) h e 8 \/CH,.*Me, )CH,*CH,*NMe, + \jCH,CH2*CH,*&Me3Approximate proportion of m-nitro-derimtive :( l O O ~ ~ .) (SS?;.) (19%) (j %. )Thcse are the only examples which aro at present available toillustrate the principle, but there can be little doubt that it is ageneral one, and that analogous series of homologous sulphoniiim,phosphoilium, arsonium, or other " .onium " salts would shorncorresponding relationships.There is reason to assume that the introduction of unsaturatedcarbon atoms (e.g., -CH=CH- groups) between a positive pole andthe benzene nucleus would cause an even more rapid damping outof the m-orienting influence. As a matter of fact, salts of the t-ypesdo not appear to have been investigated, but the close correspond-ence between ammonium salts and nitro-compounds (below)suggests that even in the &st member of such a series the m-orient-ing effect of the positive pole would be reduced to a very smallorder.The powerful op-directing influence of a negativepole has long been familiarly illustrated by the rapid and exclusiveop-substitution of phenols and thiophenols in alkaline solution.No very simple examples are available to illustrate the probabledecrease in the intensity of the effect with increasing distance betweenthe negative pole and the nucleus, but a decrease of op-reactivitycan be inferred from general experience, for instance, the circum-stance that benzyl mercaptan has never been observed to couplewith diazo-salts or undergo op-halogenation in alkaline solution.Dipoles.The semipolar double linkings in the nitro- and sulphonegroups furnish clear cases of established intramolecular ionisation : s5Negative polea.-8-60-0 )K,The orienting effect of such groups, in so far as it arises from theionic charges present, might be expected to be that of a free poleii, 938.86 S.Sugden, J. B. Reed, and H. Wilkins, J., 1925, 127, 1525; A., 1925132 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.corresponding with the end of the dipole nearer the nucleus, some-what diminished, however, by the partly compensating contraryinfluence of the more distant pole of opposite sign.In illustration of this principle, the estimated proportions inwhich m-substitution occurs in the nitration of nitrobenzene,86phenylnitromethane, and p-phenylnitroethane may be comparedwith the corresponding data for the ammonium salts referred toabove : *'(48%) (13%)Each of these figures is definitely less than the corresponding onefor the free positive ion, and the diminution may represent thecompensating influence of the terminal negative pole.Primary,secondary, and tertiary benzylamine and p-phenylethylamine saltsgive lower values than the corresponding quaternary compounds,and it is suggested 83,84 that they also exemplify dipole action.The above series also illustrates the diminution of the effect withdistance, which, in addition, is indicated by certain observations onthe nitration of sulphones ; and the far stronger damping effectof the -CH:CH- group as compared with the -CH,-CH,- group isshown by a comparison of p-phenylnitroethane and w-nitrostyrene : 89+ -)&&*Me(mainly meta-.) (30% meta-.) (only traces of mete-.)The investigation of sulphone compounds referred to aboveenables the compensating effect of the negative end of a dipole to beillustrated in another way.Sulphonic acids are strong electrolytes,and their anion contains, in addition t o the doubly-charged sulphuratom, three equivalent, negatively charged oxygen atoms. Sul-phonic esters, on the other hand, cannot undergo ionisation, andtherefore contain two negatively charged oxygen atoms and aneutral oxygen atom. The removal of the alkyl group thus resultsin the charging of the oxygen atom to which it was attached, and theeffect of increasing by this means the total compensating negativecharge in the ratio 312 is shown in the following comparison of the* a A.F. Holleman and B. R. de Bruyn, Rec. trav. chim., 1900, 19, 79;A., 1900, i, 481.8 7 J. W. Baker and C. K. Ingold, J., 1926, 2462; A.. 1131.8 8 R. F. Twist and S. Smiles,>., 1925,127, 1248; A.,'1926, i, 902; comptareC. K. Ingold, E. H. Ingold, qnd F. R. Shaw, Chem. and Ind., 1926, 45, 836.Compare also N. Martinet and A. Haehl, Compt. rend., 1921, 173, 775; A , ,1921, i, 864.8' B. Priebs, Annalen, 1884, 225, 347; A., 1886, 160ORGANIC CHEMISTRY.-PART 11. 133results obtained in the nitration of a benzylsulphonic ester and thecorresponding (ionised) acid :0-)CH,.&/O-+\O-(32% mets-.) ( 14y0 meta-.)(ii) Theoretical Considerations.-In view of the electrical constitu-tion of matter, the circumstance that positive and negative poles,respectively, represent the most powerful known meta- and ortho-para-directing in%uences strongly suggests that m-orientation isassociated with an attraction, and op-orientation with a repulsion,of certain nuclear electrons by the directing group.This consider-ation provides a starting point for the interpretation of older theoriesof the orienting action of groups.The theory of alternating residual affinity by which B. Fliirscheimhas with considerable success interpreted orienting effects, as well asthe theory of alternately polarised atoms with which D. VorlBnder,for instance, illustrated his observations, must now both be admittedto lead t o certain inconsistencies. In particular, both are affectedby the circumstance that, whatever may happen within the benzenering itself, there is, in certain cases, a demonstrable absence ofalternation in the side chain (compare the homologous ammoniumsalts and nitro-compounds).Nevertheless, both views containmany enduring features, which it is desirable to recognise beneaththe different modes of expression.The alternating affinity figure (I) for op-substitution, interpretedin terms of the electronic theory of valency, means that,, relativelyt o hydrogen, the atom X allows its electrons to come more underthe iduence of the positive atomic nucleus of C,, which to a corre-sponding extent relinquishes its control of electrons held in con-junction with Corttho (11).The alternate polarity figure for the samecase represents Cortho as negative relatively to C,, which it is to agreater or less degree if the adjustment mentioned has occurred (111).I n formula (11), the p-position is reached by mutually accom-modating adjustments of electrons from the two double bonds,and another method of attaining the ssme end is to use the con-ception of direct para-affinity exchange (IV) ; on this view a weaksecond-order effect might reach the m-position..134 ANNUAL REPORTS ON THE PROQRBSS OB CHEMISTRY.The formation of residual affinities (represented by loosely-heldelectrons) in the op-positions accords with the fact that op-orientedsubstitutions arc often practically instantaneous a t the ordinarytemperature, whilst m-substitutions are notoriously slow.Oneconception, not essentially new, of m-substitution is that it is aresidual effect produced by the disappearance of free affinity fromthe oppositions, and this might arise from the reversal of the pro-cesses represented in (11) and (IV). This, it may be remarked, a tleast seems to explain why it is that in the absence of other dis-turbances the effect of a weak op-orienting group, like methyl,outweighs that of a strongly m-directing group, such as -NMe,, incompetition, and why the further substitution of a mono-substitutednaphthalene (or anthraquinone) containing a m-directing group(NO,, SO,H, CN, CO,H, etc.) in one ring always occurs in theunsubstituted nucleus.The various series of papers in which views of this type haverecently been expressed 90 differ in the details, and the taskof presenting a connected account is not without difficulties ; more-over, there are many points which are quite incapable of definitedetermination a t the present time.Thus electron shifts originatingin an atom with a latent valency may be taken to represent either amomentary complete covalency displacement leading to an “ activephase,” or a residual valency displacement varying in amount butmore or less permanently present in the molecule :I-*%Syinklo!s ’.’$ and r‘.’$(VI.) denote establishment of i - and ..I- respectively.\ Y& \, A’”’(V.) 11-1;The evidence on this question provided by the physical properties ofbenzene derivatives will be considered in a later section. The otherpoints requiring elucidation fall mainly under three headings : (a)the origin of the orienting influence in groups other than poles anddipoles, ( b ) the mode of transmission of the effect through thenucleus, (c) the mechanism of the substitution which ensues at theactivated position.The remainder of this section will be devotedto a discussion of these points (taken in the reverse order) in so faras recent experiments seem to assist in their elucidation.(iii) Action of Substituting Agents.-If the development of residualvalencies in the nucleus (I1 or IV) is accepted, it is necessary toA. LEtpworth, J., 1922, 121, 416; J. Allan, A. E. Oxford, R. Robinson,and J.C. Smith, J . , 1926, 401: A., 397; A. W. Francis, J. Amer. Chem.Soc., 1926, 48, 1631; A., 828; H. J. Lucas, ibid., p. 1827; A,, 943; C. K.Ingold and E. H. Ingold, J., 1926, 1310; A., 833; C. K. Ingold and P. G .Marshall, ibid., p. 3080ORGANIC CHEMISTRY.-PART 11. 135assume that, after the preliminary attachment of the reagentmolecule has occilTred, some much more powerful factor operatesand ca,rries the process to completion by a comparatively directroute. It may be thought that the tendency of hydrion andhydroxide ion to form undissociated water will frequently providethe necessary driving force, and this view is embodied in thefollowing symbolic expression for a nitration (6 + and 6- denotefractional charges, and the arrows the assumed directions of electrondisplacement) : 91Possibly the reason why hypochlorous acid chlorinates more easilythan it oxidises aromatic compounds is that the tendency to formundissociated water from its ions is greater than the tendency t oform ionising hydrogen chloride.This conception assumes the prior addition of an incipientlyionised molecule.The alternative is to suppose 92 that a small partof the reagent is fully ionised and that the attack is by the positiveion ; and it is a t first sight a credible alternative because there areclear cases of nuclear attack by undoubted positive ions, forexample, diazonium ions. So far as chlorination by hypochlorousacid is concerned, however, the issue has been ingeniously resolvedby F. G . Soper and G.F. Smith,93 who have shown by dynamicexperiments that in the chlorination of a phenol the reaction occursbetween the phenoxide ion and the hypochlorous acid molecule.The great reactivity of the phenoxide ion, a s compared with mole-cular phenol, accords with the very strong op-orienting effect whichwould be expected to arise from the repulsion of electrons by a,negative pole. That the second factor entering into the expressionfor the reaction velocities is the concentration of the hypochlorousacid molecule, clearly shows that this, and not the hypotheticalpositive chlorine ion, is the halogenating agent ; for the concentrationof the positive ion would be proportional (HOCI =e= OH' + Cl') tothat of the undissociated hypochlorous acid divided by the hydroxyl-ion concentration (which was varied in the experiments), so thatthe assumption of chlorination by the ion would lead to totallydifferent velocity relations. It is probable Bd that similar con-clusions apply to chlorination by chlorine and to other halogenations.9 1 C.K. Ingold and E. H. Ingold, Eoc. cit.02 Compare H. Baines, J., 1922,121, 2810; V. Cofman, J., 1919,115, 1040;93 J . , 1926, 1552; A., 831. Idem, ibid.A. W. Francis, J . Amer. Claem. SOC., 1925, 47, 2340; A., 1025, i, 1261136 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,A general conception of aromatic substitution must envisagesubstitutions depending, not only on the dissociation of the reagentinto ions, but also its separation into neutral radicals,91 and in thisconnexion recent observations on the electrolytic oxidation ofaromatic compounds are of considerable interest; for an anion oncontact with its anode presumably becomes a neutral radical.Theexperiments 95 alluded to show that a so-called '' negative "hydro@ group is introduced into the nucleus in the same positionsas those in60 which a " positive " nitro-group would enter ; forinstance :Me MeM e 0 -+ M e o O HThis is to be expected, for the neutral hydroxyl radical (or O.SO,Hradical, if the electrolysis is in sulphuric acid) will contain one electronless than t,he number required to form the stable group, and willtherefore seek out the negative centres of the aromatic nucleus,simulating in this respect the behaviour of a " positive " group.(iv) Nuclear Transmission of Orienting Effects.-The decisionbetween mechanisms which employ the conjugation of the Kekul6double linkings (11) and those which assume direct para-transferenceor shift (IV) must be separately decided in each group of cases.It is, however, germane to the general question to refer here to thecontrast between the remarkable facility with which orientinginfluences traverse an aromatic nucleus and their apparent almosttotal inability to pass through even one carbon double linkingsituated in a side-chain.The contrast between the ' almost complete inhibition of p-sub-stitution in the nitration of nitrobenzene and the facility with which0-substitution (and p-substitution) takes place in w-nitrostyrene,despite apparent analogy based on the conjugation of the systems,has long been recognised, and now a still more striking illustrationhas been provided.96 In the nitration of 4-phenylpyridinium sul-phate the effect of the pole after traversing the pyridine ring is9 5 F .Fichter and J. Meyer, Helv. Chim. Acta, 1928, 8, 74; A . , 1925, i,800; F . Fichter and P. Latter, ibid., p. 438; A . , 1925, i, 1055; F. Fichterand M. Adler, ibid., 1926, 9, 279; A., 809; F. Fichter and-M. Rinderspacher,ibid., p. 1093.$6 R. Forsyth and I?. L. Pyman, J., 1926, 2912ORGANIC CHEMISTRY .-PART 11. 137capable of producing a Iarge proportion of m-substitution in thebenzene ring (28.5% isolated out of 79.2% of identified isomerides) :in the case of 2-phenylpyridinium sulphate, the meta-proportion ispossibly a little higher, but certainly of the same order (34.9%isolated out of 52.376) ; in the case of 3-phenylpyridinium sulphateit appears to be small (none isolated out of 64.3%).The two viewsof the orienting process may be expressed by formule (VII) and(VIII), in which the applications to the 2- and 4-phenyl compoundsare represented together :Ph---It 'I , ,and i t is noteworthy that the numerical data approximately accordwith anticipation based on a comparison with tertiary benzyl-ammonium s a h , Ph+$%+-NR,H, using (VIII).Further examples emerge from recent studies with diphenylcompounds.97 pp'-Dibromodiphenyl nitrates mainly in the 0-position. The prior introduction of a m-nitro-group in one ringcauses, however, simultaneous o- and m-nitration in the other :whilst the presence ,of an o-nitrogoup in one ring leads exclusivelyto m-nitration in the other (* represents the positions of sub-st.itution) :1 +(v) Orienting Influence of Groups.-The orienting effects of groupswhich do not contain poles are naturally dominated by the con-stitutions of the groups.op-Directing groups.It is a commonplace of orientation theoriesthat groups attached t o the nucleus by unsaturated atoms, that is,those which possess latent valencies, lead invariably to op-orient-ation in the ordinary substitution processes. For the neutral atomsN, 0, F, which belong to this class and, in the combined state,contain the same number of electrons, it has been shown that the" H.G. Dennett and E. E. Turner, J., 1926, 476; A., 390; R. J. W.Le FBvre and E. E. Turner, ibid., p. 2041; A., 629. For similar but lesscomplete studies of the nitration of diphthalylbenzidine, and of diphenylitself, see also idem, ibid., p. 1789; A., 946; H. H. Hodgson, ibid., p. 2384;A., 1133; F. Bell and J. Kenyon, ibid., p. 2705; A., 1241.E138 A."UAL REPORTS ON TEE PROGRESS OF CHEMISTRY.oporienting power runs parallel with those properties which areinterpreted as indicating activity on the part of the unsharedelectrons ; in other words, the op-directive power diminishes withincreasing strength of the restraining nuclear charge, that is, withincreasing atomic number : N>O>F. This order is inferred fromthe observations 98 represented byasi@f? HAc M G O O N e 4% NMeAc ~ 3 % ~LC,()F OMe ,where the figures denote the isolated or estimated proportions ofthe mononitro-isomerides obtained on nitration of the correspondingo-disubstituted compounds.The complete interpretation of suchresults as these involves a consideration of the disturbances whichmight be caused by the alkyl and acyl groups, but it may be noteda t once tbat in the second and third examples the nitrogen atom stillcontrols the situation despite the fact that the distribution of alkyland acyl groups is such as to handicap its action.Alkyl groups contain no unshared electrons ; they neverthelesspromote op-substitution, although not very powerfully, and sub-stitution of the same type occum if the carbon atom adjoining thering is replaced by a tetracovalent silicon or tin at0rn.~9 There isreason to think that these atoms allow their shared electrons to becontrolled by the nucleus of an attached carbon atom to a greaterextent than would hydrogen in a similar situation.g9a At any rate,this general statement seems to accord with the effect of replacinghydrogen by alkyl in composite groups, when an increase in theop-orienting influence (or diminution in the m-directing influence) ofthe entire group takes place.This is interpreted in accordancewith G. N. Lewis's electron-displacement mechanism and is wellillustrated by the nitrations of benzoic esters : 1C6H,.C0,H C,H,.CO,Me C6H,*C02Et23% 1.5% 6% 66%- - - -(m-, 80*27&.)2 (wL-, 73.27A.) (T~L-, 68.474.)'8 C.K. Ingold and E. H. Ingold, J., 1026, 1310; A., 833; E. L. H o h e sand C. K. Ingold, ibid., p. 1328; A., 831..a9 D. Vorlander, K . Kunze, and E. Sclmoodter, Be?., 1926, 58, 1900; A .1925, i, 1255.9esH. J. Lucas and H. W. Moyse, J . Amer. Chem. Soc., 1926, 47, 1459;A., 1925, i, 770; H. J. Lucas, T. P. Simpson, and J. M. Carter, ibid., p. 1462;A., 1925, i, 766.1 A. F. Holleman, Rec. trav. ciiim., 1899, 18, 267.Probably the true value for the un-ionieed carboxyl group is slightlyhigherORQANIU CHEMISTRY.-PART II. 139and mixed pyrocatechol and quinol ethers : 337.8% 62.2% 35.7% 64.3% %:Ea()OMe OPTS M e O D M e O o P r aIn the last two series, the order of the effects of the ethoxy- andn.propoxy-groups is not the same, and the investigators attributethis to the distribution over the molecule of a considerable propor-tion of the effect of the larger alkyl group.The opposite influence of acyl groups, namely, the enhancementof m-orienting and the weakening of op-orienting effects, has longbeen recognised, and is familiarly illustrated by the fact that sub-stitutions in o- and p-alkyloxyphenyl esters are controlled by thealkyloxy-group.The effect may be consistently interpreted as theresult of a partial appropriation of electrons by the carbonyl oxygenatom ; this confers partial dipolar (betaine) character on thecarboxyl and carboxylamide groups, and in phenyl esters the smallpositive charge next the nucleus, although it may not be strongenough to bring about m-substitution, will oppose the op-orientingmovement of the lone electrons :Many more or less complex illustrations of this phenomenon areavailable, but some particularly striking examples in which theeffect is enhanced by the use of bivalent acyl groups, like succinyl,have recently been published? Under conditions in which succinanil,phthalanil, etc., yield mainly p-nitro-derivatives, the correspondingp.tolils substitute to the extent of 76-84y0 in the position indicated :Succinyl, phthalyl, 3-nitrophthalyl,Ra = { tetrachlorophthalyl.As the authors remark, the bivalent acyl radical '' doe0 not suffici-ently influence the amino-group to enable m-substitution to occur,but i t so reduces its directive influence in the case of p-toluidine asJ.Allen, A. E. Oxford, R. Robinson, and J. C. Smith, J., 1928, 401;A,, 397.0. L. Brady, W. G. E. Quick, and W. F. Welling, J., 1926, 127, 2264;A., 1926, i, 1400140 ANNEAL REPORTS ON THE PROGRESS OF CHEMISTRY.to enable the comparatively feebly directive methyl group to takecontrol.’’m-Directing groups. The halogens are recognised from thestability of their ions and other evidence to be elements of highelectron-affinity, and the consideration of such a series asC,H5CH2C1 C6H5*CHC12 C6H5’CC13 } (for nitration)(meta-, 404.) (meta-, 35%.) (meta-, 64o/,.)shows that the introduction of each halogen atom independentlyoperates in favour of m-substitution. The action, in fact, is theopposite of that associated with alkyl groups, and the contrast hasbeen illustrated 87 by the introduction of methyl and bromine inplace of the hydrogen atoms of the rather strongly m-orientinggroup -CH,*NO, :In these cases, the sharing of the lone halogen electrons with theattached atom is impossible without disruption of the molecule, andin chlorobenzene, etc., where the sharing process can, and pre-sumably does, occur (leading to op-substitution), it may be supposedthat there is a simultaneous attraction towards the halogen nucleusof all its electrons, shared and unshared, weakening the op-orientingeffect. Probably two simultaneous effects, ‘-+Cl, which may betermed ‘‘ tautomeric,” g-1, and inductive,” + , would be propa-gated by different paths in the nucleus, and it is doubtless in thisdirection, amongst ot,hers, that the explanation of many obscurephenomena, for instance the 0-lp- ratio, is to be sought.In thecarbonyl group and similar groups, there will be a shifting ofelectrons towards the more electronegative element and the tauto-meric and inductive effects will collaborate, Ph+CO. In theamidine salt group, the effect of a positive pole is superimposedin addition ; accordingly benzamidine nitrates almost wholly in them-position.6One is reminded of the problem of the o-lp-ratioby the recent re-investigation of the nitration product of benzil,which contains mmr-, om’-, and 00’-derivatives (70%, 20%, and lo%,respectively) but no considerable quantity of p-substitutedisomerides.6 Amongst the m-orienting groups, the rule seems to beIc-)1 1(-4The o-lp-ratio.5 R.Forsyth, V. K. Nimkar, and F. L. Pyman, J., 1926, 800; A., 611.6 F. D. Chattaway and E. A. Coulaon, ibid., 1070; A., 728ORGANIC CHEMISTRY .-PART IT. 141that those with a real double bond similar to that in benzoyl com-pounds give mainly o-by-products, whilst those composed whollyof single (or semipolar double) bonds yield p-products in greateFquantity. These and other regularities of a like kind may be partlycollated (probably steric hindrance and the varying electron-seeking tendencies of different reagents are also factors) by suppos-ing that tautomeric disturbances reach the para-position moreeasily than the ortho-, whilst with inductive disturbances, whichare generally weaker, the reverse is the case.Using T and I forthe two types of disturbance, and + and - for promoting andimpeding eflects, the different cases may be tabulated :(i) + I = o>p (toluene).(ii) - I = p>o (phenyl- and benzyl-ammonium salts, benzene-(iii) -.T--I = o>p (benzoyl compounds, nitrobenzene).(iv) + T - I = p>o (halogenobenzenes, phthalanil).The spatial factor seems to be present in the predolninatingp-nitratioxi. of tert.-b~tylbenzeee,~ and the effect of varying thereagent is well brought out by recent studies on the mercurationof toluene and nitrobenzene.s Comparison of the results with thoseobtained for nitrationsulphonic acid, benzotrichloride).is instructive :The observations are, of course, on a footing with the well-knownpredominating o-mercuration of benzoyl compounds. In themercuration of these compounds, as in their nitration, the quantityof o-by-product exceeds the quantity of p - ; the noteworthy featureis that in mercuration the quantities of ortho- and para- takentogether exceed that of the meta-derivative.A considerable amountof substitution in the position adjacent to the nitro-group also takesplace in the mercuration of the three nitroto1uenes.QIn view of its possible connexion with the subject, reference maybe made to H. Wieland and H. Jung’s discovery lo that the long.known product of the oxidation of trinitroresorcinol with bromineS. Coffey, J., 1925, 127, 1029; 0. Dimroth, Annalen, 1925, 445, 148;CompereS. Coffey, J., 1926, 637; A., 628; ibid., p.3215; H. Burton, F. Ham-’ D. F. du T. Malherbe, Ber., 1919, 52, 319; A., 1919, i, 261.A., 1926, 312; J. Jurgens, Rec. trav. ohirn., 1926, 45, 61; A., 312.A. F. Hollemen, Rec. trav. chirn., 1923, 42, 356.mond, and J. Kenner, ibid.. p. 1802; A,, 966.lo Annden, 1925, 445, 82; A . , 1925, i, 1374142 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.water is a derivative of isovaleric acid, in the formation of whichpcarbon atoms have become united :/NO, h7 0,*H/)OH Br b-CO,HNOQNO, NO,*Br,C--g;CBr,*NO,Special Mechanisms.-Doubtless there are many substitutions inwhich special mechanisms determine a particular type of result ; insuch cases, either the circumstances of the reaction or collateralevidence of some other kind should indicat'e, if it does not elucidate,the cause of the anomaly.An interesting example is furnished byrecent work on the nuclear alkylation of phenols, through their salts,in non-ionising solvents (benzene, toluene) by alkyl halides, which,when ionising solvents (methyl and ethyl alcohols) are employed,cause exclusive substitution on oxygen.11 In these nuclear alkyl-ations, the substituent invariably enters the ortho-position, evenalthough the para-position may be unoccupied. The relevantcircumstances are, first, that the reaction occurs only in non-dissociating media, and secondly, that only reactive, readily hydr-olysable, alkyl halides can be used. This suggests, fist, that thereaction is one which requires the presence, not of the phenoxide ion,but of the undissociated metallic sa1t,l2 and, secondly, that theincipient intramolecular ionisation of the alkyl halide must exceed acertain necessary minimum.Both points are incorporated in thescheme :I !..j ~ +HNa Naa+d 4 OH0 IS- -+@,O) )y + Na' + I', >&.-,. RSf + +?t" (0 IS-c I'Hand the possibility of a cyclic mechanism is clearly established by therelated rearrangements of aryl allyl ethers, in which the allyl groupmigrates to the ring. That these reactions are actually analogous is11 L. Claieen, 2. angew Ch~m., 1923, 36, 478; A., 1923, i, 1094; idem,D.R.-P. 412169; A . , 1925, i, 1410; L. Claisen, F. Kremers, F. Roth, andE. Tietze, Annalen, 1925,442, 210; A., 1925, i, 656; L. Claisen and E. Tietze,ibid., 1926, 449, 81; A., 1034.11 The existence of undissociated salts ( e .g . , sodium iodide) in feebly ionis-ing organic solvents can probably be inferred from the fact that such solutions,&cording to measurements of conductivity, appear to conform to the require-ments of the law of masa action within wide limits (Professor H. M. Dawson,private communication)ORGANIC CHEMISTRY .-PART II. 143plainly indicated by the fact that here again the group enters onlythe ortho-position even when the para-position is unoccupied. I nthese cases, however, the cyclic mechanism may be demonstrated l3by the use of a y-substituted allyl group, which becomes an a-sub-stituted allyl group in the product of the rearrangement :Note.-A considerable body of work has recently been carried outon the replacement of atoms and groups other than hydrogen, and onthe influence of substituents on the reactivity of atoms and groupssituated in another side-chain; limitations of space render itdesirable to postpone reporting on these two important branches ofthe general theme.Physical Properties of Benzene Derivatives.Some interesting parallelisms have been drawn between the effectof the presence of a group in an aromatic compound on its meltingpoint, boiling point, and dielectric constant, on the one hand, andthe orienting influence of the group, on the other.Such comparisonsare instructive because they indicate that directive influence is toa considerable extent a permanent specific property of the moleculeand not merely a, temporary factor brought into play only a t themoment of reaction through some " activation " process.Melting Point and Boiling Point.-".W. Francis, D. H. Andrews,and J. Johnston l4 point out that if a, series of monosubstitutedbenzenes, C,H,X, are arranged in accordance with Holleman'sseries for diminishing op-orienting power and increasing m-orientingpower, the m. p.'s and b. p.'s fall through the op-series and risethrough the m-series ; and a similar relation exists for compounds ofthe type HX :op-Orienting. m. Orienting.r A . X = OH>NH, > Br > C1 > CH, > H <CHO<N0,<S0,H<C02HC,H,X.42' -6' -31" -45' -994' 5' -13' 5 O 66' 121' {z::: 183' 1 8 4 O 158' 132" 110" 80' 179' 210" - 249O{z:p": 100" -39" -69' - 83' -153' -258' -21' -HX .0°-77" -87' -112' -184' -259' - - - 90101013 L.Claisen end E. Tietze, Ber., 1925, 58, 275; A . , 1925, i, 389; ibid.,1 4 J. Anter. Chem. SOC., 1926, 48, 1624; A,, 828.-1926, 59, 2344; A., 1241144 ANNUAL RBPORTS ON THE PROGRESS OF CHEMISTRY,The correspondence, although striking, is obviously imperfect ;thus the order chosen for the orienting action of NO, and CO,H isnot that which would be deduced from the relative proportions ofm-derivative given by nitrobenzene and benzoic acid on nitration ;and, again, the position given to OH( >NH,) is probably based onsubstitution reactions (e.g., aqueous bromination) in which the realorienting group is not -OH but the pole -Oo (p. 135).Turning to disubstituted benzenes, C,H,XY, the same workers,and also I.A. Pastak,15 direct attention to a genera1 rule governingthe relative melting points of 0-, m-, and p-isomerides. It is that,whereas the p-compound has the highest m. p., of the other twoisomerides that in which the groups co-operate in their directiveeffect has the lowest m. p. Both parts of the rule are violated, forexample, by the chlorobenzaldehydes, in which the m. p. sequence iso >p > m instead of p > m > o ; nevertheless it appears to bold goodin about 70-80% of the available examples.Such rules as these, even when they may not be perfectly obeyed,clearly point to the existence of a connexion, however indirect,between the properties under comparison, and it will be agreed that" any indication may be valuable in a field in which so little is knowndefinitely.')Dielectric Constant.-In the same paper, Francis, Andrews, andJohnston direct attention to an approximate regularity in thedielectric constants of the monosubstituted benzenes representedin the table above. Like the m. p.'s and b. p.'s, these constantsfall from phenol to toluene and rise from benzene to nitrobenzeneprovided that we except chlorobenzene, the constant of which ishigher than that of phenol. Similar approximate relations betweenthe dielectric constant and orienting properties of compounds havebeen pointed out previously.16The interest which a t present centres around the dielectric con-stant, however, arises from the fact that a theory bas been pro-vided whereby it is possible t o trace the connexion between theconstant and certain definite structural properties of the molecule.l*It is necessary to consider the chain of reasoning briefly in order tobring out the power, and the present limitations, of the method as ameans of elucidation of molecular structure.1s J.Chim. phys., 1926, 22, 48, 264; A., 1925, i, 531; ii, 759.16 H. G . Rule, J., 1924, 125, 1121; H. G. Rule and T. R. Patterson, ibid.,p. 2155.1 7 p. Debye, Physikal. Z., 1912, 13, 97; J. J. Thomson, Phil. Mag., 1914,27, 757; A., 1914, ii, 450; C. P. Smyth, ibid., 1923, 45, 849; 1924, 47, 530;J. Amer. Chein. SOC., 1924,46, 2151; .4., 1924, ii, 810; R. Gans, Ann. Phycrik,1921, 64, 481.18 Compare G . N. Lewis, '' Valency and the Structure of Atoms end Mole-cules " (1923)ORGANIC CHEMISTRY .-PART 11.145If in a molecule the mean electrical centre (analogous to centre ofgravity) of all the electrons and the corresponding centre of all thepositive atomic nuclei do not coincide, the molecule as a whole willbe equivalent to a dipole and will possess a definite electric moment(v). In the presence of an electric field, such molecules will tend toorient themselves in the direction of the field ; but this tendencywill be opposed by thermal agitation, with the result that there willarise a statistical average degree of alinement depending on thetemperature. The molecular fields thus reinforce the exciting fieldpassing through the substance. The moments of the orienteddipoles will, however, be greater than in the undisturbed condition,because the field itself will create a further intramolecular separationof & charges in the same direction until the effect of the whole field(original + induced) is just balanced by the restoring forces.Thegross increase in the field (determining the dielectric constant E) thusdepends on the sum of two terms, one of which (the orientation-polarisation, P,) represents the contribution, limited by temperature,of the oriented dipoles, whilst the other ( P E + PA) denotes the effectof the additional electrical separation as limited by the ‘‘ rigidity ”(“ Bindungsfestigkeit ”) of the charges. The latter term is dividedinto two parts, PA and PE, because one can be evaluated moreeasily than the other ; for the part depending on the displacementsof the relatively very light electrons (the electron-polarisation, PE) isthe only part which contributes to the ‘‘ dielectric constant “ (Le.,the square of the refractive index, 12) in the rapidly oscillatingelectric fields of visible light.The other part (the atom-polaris.ation, PA), which arises from the relative displacements of the com-paratively heavy atomic nuclei, can only be evaluated directly ifthe appropriate optical data for the far infra-red region (slowerelectrical oscillations) are available ; its chemical interest is, however,just as great as that of the dipole moment, since it also measures aspecific molecular property, namely, the tendency towards incipientdivision into ions.Debye’s equation (modified),c - 1 .M a2-1 M 4nN&2 9kT 2 = ; g + i ‘ d + P A + - - EL2,k = Boltzmnnn’s gas constant. N = Avogadro’s number.which, in accordance with the above summary may be abbreviatedto P = PE + PA + P,, applies primarily to vapours, but withsuitable modification is also applicable to dilute solutions in anappropriate solvent. Its application to strong solutions and pureliquids having dipolar molecules i s not 80 good owing to intermole.cular action, especially ‘‘ dipole association,” +=;, which tend146 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.to Iower the value of e.lg It remains to be added that in equatingPZ to the Lorentz expression [BL] a wave-length in the red region ischosen, since, for a colourless substance, this is sufficiently far fromthe (ultra-violet) frequency of the resonating electrons to rendernegligible the omitted correction for dispersion ; the correctionfactor (1 - Ai/h2) can, however, be applied if necessary.SimilarlyPA + PB can be equated t o [ R ~ ] i n f ~ ~ - ~ ~ d only if the refractive indexis taken well beyond the infra-red bands due to the vibrating atoms.T h e Dipole Moment and Atom-polarisation of Benzene.-Recently-determined values for the dielectric constant,20 refraction, and dis-persion of benzene in the liquid state near the ordinary temperaturegive P = 26.6 and PE = 25.7. Since P = Pa + PA + P,(llq.), itfollows that PA + Pp(,,g.) has the small value 0.8, and there are twoindirect reasons for inferring that the whole of this is to be laid tothe account of atom polarisation. First, similar small values ofPA+ P,(uQ,) are invariably observed in very diverse types of mole-cules provided that their projections on three space-axes are sym-metrical (marked *) : 21p-xylene.* nz-xylene.o-xylene. mesitylene.*'~iC1Ti(Co)4,*PA f PMlIq.) 1.3 4.0 7.0 1.5 2.1 - I -.-CI-C-H H--CCI* CI-C-CI Br-C-H Br--CH*II II II23.6 27.6 3.0C1-C-H I I C1- 4- H H-G-H Br-G-H H-C-BrPA pp(I1q.) 34'66 2.7Secondly, in the solid state there can be no free orientation of themolecules (P, = 0) and therefore dipole substances should show adiminution in the dielectric constant when frozen. This is wellillustrated in the case of water, for which P drops 8 units on fr.eezing :p(llq ) = ~g + PA + P,u(ii,.) = 17.: ; pn = 3.7 ; .a . P A + pp(ilq,) = 13.8.p(d.) = PE f PA = 9.0; PI = 3.7; :. PA = 5.8.Here the approximate value of the refractive index in the far infra-red is known (n2 = 4) and the derived estimates PB + PA = 9 andPA= 5.3 are in good agreement. In the case of benzene, however,there is no diminution in P on passing from the liquid to the solid,but, on the contrary, a very small increase (P<II,., 26.5 ; P(ml.) 26.9).A similar behaviour is shown by the symmetrical substance carbontetrachloride .211s L. Ebert, 2. physikal. Chem., 1924, 113, 1; A . , 1925, ii, 14; ibid., 1925,114, 430; A., 1925, ii, 262.20 W. Graffunder, Ann. Physik, 1923, 70, 225.L. Ebert, Zoc. c i t . ; J.Errera, J. Phys. Radium, 1925, 0, 390; A., 1926,226ORCANIU CHEMISTRY .-PART II. 147An eIaborate theoretical investigation has led R. Sanger 22 to theclonclusion that the dipole moment of benzene is probably zero, andi t is of interest to compare the corresponding estimate of its atom-polarisation (0-8) with that of a typical ionising substance such aswater (5.8).The Dipole Moment of Benzene Substitution Products.-A varietyof circumstances points to the conclusion that dipole moment is 8property of groups.23 The following data for benzene homologuesC,H,X ............ X = Me. Et. Pra. PrS. Bu*O.P A i- p p ( l i q . ) *..*.. 2.9 3.4 3.0 3.5 3.0apply to the liquid state, in which the polar orientation is imperfect;nevertheless the approximate constancy of the values clearly showsthat both the atom-polarisation in the aliphatic side-chain and theeffect of all the carbon atoms after the first on molecular dipolemoment are inappreciable.On contrasting these results with thefollowing series (which relate to the vapour-free polar orientation),H. Me. Et.R*OH{PA + ; : 56.3 54.7 54.9it becomes evident that an effect of the hydroxyl group is now underobservation; and, since the values of PA for hydrocarbons and evenfor water are small in comparison with these observed values forPA + P,, by far the greater part of them must be attributed to P,,which is therefore sensibly constant in the three compounds.The smallness of PA for many classes of compounds renders itpossible, as an approximation, to neglect it in comparison with P,for defhitely dipolar molecules, and to calculate the dipole momentof the individual molecule (p) from the approximate equationP - PE = 4xNp2/9kT. An interesting and important series ofdata 24 relating to benzene derivatives has been treated in this way.The values of p for some monosubstituted benzenes are as follows :CH,.Br. C1. NO,. SMe,.CeHsX{: 0.43 1.56 1.58 3.75 1.39 X lO-'*E.S.U.From these data alone it is, of course, impossible to tell in whichdirection the charges are distributed as between the group and thenucleus; but, as Sir J. J. Thomson pointed the electricmoment of a polysubstituted benzene should be the vector sum of thePhysikal. Z., 1926, 27, 165; A., 456.23 L. Ebert, loc.cit.; C. P. Smyth, loc. c i t .a4 K. Hdjendahl, Nature, 1926, 117, 896; A., 779. The dielectric con-stants were determined in benzene solution (non-dipolar solvent) and extra-polated to i h i t e dilution in order to eliminate the effect of dipole association.2 6 Phil. Mag., 1923, 46, 613; A., 1923, ii, 082148 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.moments due to the groups, provided that these groups act in-dependently and that the hexagonal symmetry of the ring is notdistorted by substitution. It follows that the investigation ofdisubstituted benzenes must reveal the relative signs of the com-ponent effects; thus the moment of p-nitrotoluene should be thesum of the moments of toluene and nitrobenzene if, and only if,the two groups cause an unlike displacement of i charges whenattached separately to the nucleus.In the following table, theexperimental values of the molecular dipole moment, g, for a numberof polysubstituted benzenes are compared with the values calculatedby compounding the moments (above table) due to the separategroups :Formula (a and ZI fromSubstance. p (obs.). p (calc.). previous table).o-Dinitrobenzene ... 5.95 x 10-18 6.50 x 10-18 l / i F + a i 2 5 2 5 G Z W = d3am- ,, ... 4.02 3.75 da2 + a2 + 2a2 C 0 8 120" = aP- ,, ... 0.8 0.00 Zero from symmetry.8-Tribromobenzene 0.3 0.00 Zero from symmetry.o-Nitrotoluene . , . . I , 3.56 3.62 d a Z + be - 2ab cos 60'P- 9 , ...... 4.30 4.18 d a 2 + bZ - 2ab cos 180°= a + bo-Chloronitrobenzene 4.25 4.75 %"a2 + b2 + 2ab cos%O"m- ,t 3.38 3.27 daz> ba + 2ab cos 120'-p-Bromonitrobenzene 2.69 2.19P- 1 , 2-52 2.17 m b 2 + 2ab cosIb-6"= a - bV'a'+b2 + 2ab cos 180°= a - bPerfect agreement is not to be expected, because, a8 the values fortribromobenzene and p-dinitrobenzene show, atom-polansation isnot negligible; also the assumptions made in compounding thevectors are probably only approximately fulaled.Nevertheless,the results show clearly that the dipoles due to NO,, C1, and Br areof the same sign, whilst that due to Me is of the opposite sign. Sincethe dipole due to NO, must be in the direction of its semipolardouble linking, these results may be taken as establishing permanentelectron shifts in the directions :f-- __f __fC,H,.Me C,H,*Hal C,H,*NO,These are the directions deduced for the inductive dispIacementfrom aromatic substitution data, and it is of considerable interestthat the same results, supplemented by those of another worker,,,lead t o the sequencerepulsion electron attraction +- ______j Me > H c I c Br c C1 <NO,which is also in agreement with expectation based on orientation2 6 J.Errera, Compt. rend., 1926, 182, 1623; A., 779ORGANIC CREM'ISTRY .-PART II. 149reactions. Part of the large moment of nitrobenzene is, of course,due to the dipolar constitution of the nitro-group itself.It follows from the sequences N>O>Hal and Hal>O>Ndeduced for tautomeric electron-repulsion and inductive electron-attraction in oriented substitutions that the f i s t effect is at amaximum and the second a t a minimum for N ; hence, when thesign of the dipole in dimethylaniline has been determined, it shouldbe possible definitely to answer the question whether tautomeric,like inductive, effects are associated with a permanent displacementof the electrons.Concluding Notes.-The Reporter is more than usually consciousof the fact that the foregoing account is far from representative ofthe different types of work falling within the Homocyclic Division ofOrganic Chemistry which have signalised the year under review,and one of the most serious omissions relates to the study of naturalproducts in which noteworthy advances (apart from those con-nected with muscone and civetone) have been made, includingthe complete elucidation, by analytical methods and synthesis, ofthe constitution of thyroxine.This important investigation, how-ever, is being dealt with in the Biochemical section of these Reports,and partly on this account, and partly because the space which hasbeen occupied is already too great, it seems desirable to leave thegeneral topic of natural products to be dealt with on a futureoccasion.It should also be mentioned that the supposed '' meta-ring ''compoundsdiscussed in the Annual Reports for 1920 (p. 73) have now beenshown to possess different constitutions : 27C. K. INGOLD.8 7 A. F. Titley, J., 1926, 508; A., 512150 ANNUAL REPORTS ON TEE PROGRESS OF CHEMISTRY.PART III.-HETEROCYCLIC DIVISION.Pyrrole Derivatives.T. M. LOWRY has pointed out that the nitrogen atom in thepyrrolidine nucleus of the nicotinium ion must be regarded a8asymmetric, a view supported by the fact that, like some otheralkaloids, nicotine changes its sign of rotation on conversion into asalt, for example, nicotine [a]D -169' ; nicotine acetate, [a],, +IS*So.I n the course of a paper mainly concerned with the configurationof certain amino-acids exhibiting dextrorotation, P.Karrer, K.Escher, and (Mlle.) R. Widmer conclude that 1-proline, I-hygricacid and I-stachydrine must belong to a group the configuration ofwhich is typically represented by 1-asparagine. The group includesd-glutamic acid, d-glutamine, d-ornithine, and d-lysine, and theysuggest that these natural constituents of protein, as well as someof the simpler alkaloids, such as nicotine, possess a uniformconfiguration.G. Korschun and (Mme.) C.Roll are of opinion that the first stagein the action of hydrazine on asdiketones is the direct addition ofone molecule of the reagent, after which elimination of water mayoccur in either of two ways :(a) elimination of imino-hydrogen with hydroxyl, followed byring closure to a 1 : 2-diazine.( 6 ) a hydrogen atom of the methylene group is eliminatedwith the hydrokyl group, followed by ring closure to an amino-pyrrole.H,*CR(OH)*NH*NH, +CH,*CR:N*NH, x HRCOR C~HR-COR.1 CH:CR*NH*NH, ~ YH:CR.T.NH,~HR-COR CR=CRThe relative mobilities of the hydrogen atoms, which depend onthe nature of the substituents and the conditions, especially thetemperature, determine which reaction will take place.On thisview of the mechanism, the heats of formation of an aminopyrroleand the isomeric 1 : 2-diazine should be approximately the same,and this has been found t o be the case for ethyl 1-amino-2 : 5.di-methylpyrrole-3 : 4-dicarboxylate (I), 15664 cal., and ethyl 3 : 6-di-Nature, 1926, 117, 417; A,, 338.Helv. C h h . Acia, 1926, 9, 301; A., 505.* BUR. Boc. c h h . , 1926, [iv], 39, 1223; A., 1 1 ORGANIC CHEMISTRY.-PART XI. 151methyl-4 : 5-dihydro-1 : 2-diazine-4 : 5-dicarboxylate (11), 1588.2ca1.4Syntheses of many simple and complex pyrroles have beendescribed by H. Fischer and his co-workers chiefly by methodsreferred to in previous report^.^ Pyrryl ketones have been success-fully prepared by the Friedel-Crafts process, both with aryl and withalkyl radicals,6 and new syntheses of cryptopyrrole (2 : 4-dimethyl-3-ethylpyrrole) and of xan thopyrrolecarboxylic acid, both importantdisintegration products of chlorophyll and blood pigments, havebeen recorded.' A study has also been made of the colouringmatters formed in Ehrlich's test (p-dimethylaminobenzaldehyde inhydrochloric acid).8 Thus ethyl p-5-carbethoxy-2 : 4-dimethyl-3-pyrrylmethylmalonate (111) gives the deep-violet coloured ethylp-5-p-dimethylaminobenzylidene-2 : 4-dimethyl-3-pyrrylmethylmal-onate (IV).(111.) NH-- I cMe>C*CH,~CH(CO,Et)z -+ C (C0,Et):CMeAetioporphyrin and the corresponding aetiohaemin and aetio-phyllin were isolated by Willstatter in 1913 as the parent substancesof a number of proximate degradation products of chlorophylls andhsemoporphyrins and have since been prepared from porphyrinsfrom other sources.Aetioporphyrin is therefore an importantproduct in these difficult and complex investigations and its synthesisby H. Fischer and J. Klarer is of considerable interest both to thebiologist and to the chemist. Cryptopyrrole (2 : 4-dimethyl-3-ethylpyrrole), on bromination in cold acetic acid, yields a compound,C,,H,,N,Br,, believed to be represented by (V), which is convertedGEt-fiMe GEt-fiMe GMe-GEt7.NH-F YNH.?(v.) YNH.CBr I_;H QH C==C CH (lrI.)CMeICEt t- Et=-CMeym=+ 2 . 9 ?.N=F*CH,BrCMeXEt* A. Gounder and (Mme.) C. Roll, ibid., p. 1222; A,, 1155.1923, 20, 136; 1924, 21, 124; 1925, 22, 133, and Annalen, 1926, 450,H.Fischer and F. Schubert, 2. phy8iOl. Chem., 1926, 155, 99; A., 737. ' With B. Wdach, Ber., 1925, 58, 2815; A., 1926, 178; with J. Klarer,With C. Nenitzesou, 2. physioz. Chem., 1925, 145, 295; A., 1926, 178.AmzcEZen, 1926, 448, 175; 450, 181 ; A., 962, 1261 ; compare H. Fischer109; A., 1256.Anitah, 1926, 447, 48; A., 412.and B. U'elach, ibid., 1926, 450, 164; A,, 1261152 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.by sulphuric acid into a substance (VI) indistinguishable in crystallographic characters, absorption spectrum, and solubility fromWillstatter's aetioporphyrin. With ferric chloride, it gives thecorresponding aetiohsmin and with magnesia and potassiumhydroxide in methyl alcohol the appropriate aetiophyllin.Anisomeric substance, isoaetioporphyrin, has also been obtained,1° aswell as other substances of this series.ll The name " porphin " issuggested for the parent substance of this type free from p-sub-stituents and efforts are now being made to synthesise it.Indole and Allied Substances.Work in this group has been, as usual, largely concerned withproblems bearing on the constitution of natural products or theirsynthetic analogues, but a few observations on the primary materialshave been made. J. van der Lee l2 suggests that in Nenitzescu's 13preparation of indole by the reduction of ow-dinitrostyrene withiron filings and acetic acid, in which a yield of 30% is claimed, thointermediate products must be ow-diaminostyrene and o-amino.phenylacetaldehyde.In continuation of work on the now well-known transition ofindole to quinoline, G.Heller and collaborators l4 have shown that,although the main product of the action of diazomethane on isatinis 2 : 3-dihydroxyquinoline, some 3 : 4-dihydroxyisoquinoline isalso formed. B-chloro- and 5-bromo-isatins furnish the corre-sponding 2 : 3-diketotetrahydroquinolines with the halogen ineach case in the 6-position.E. C. Kendall, A. E. Osterberg, and B. F. MacKenzie,lk inattempting the synthesis of substances with formuls akin to thatsupposed by the same authors to represent the constitution ofthyroxine, have prepared an interesting series of complex indolederivatives, but the main object of this work has become ofsecondary importance in view of Harington's l6 demonstration thatthis hormone is not heterocyclic in structure.W.H. Perkin and L. Rubenstein 1' found great difficulty in thepreparation and use of phenylhydrazines of the type(MeO),C,H,*NH*NH,H. Fischer and P. Halbig, Bnnalen, 1926, 448, 193; 1926, 450, 151 ; A.,963, 1256.11 H. Fischer and others, ibid., pp. 132, 201; A., 1256, 1261.Rec. trau. chim., 1925, 44, 1089; A., 1926, 179.Ber., 1925, 58, 1063; A , , 1925, i, 973.Ibid., 1926, 59, 704; A., 620.J. Amer. Chem. isoc., 1926, 48, 1384; A., 734; compare L. Kalb andBiochem. J., 1926, 20, 293, 300; A., 644, 724.co-workers, Ber., 1926, 59, 1868, 1860; A,, 1151, 1152.1' J., 1926, 357ORGANIC CHEMISTRY.-PART III. 153required for the production of a series of dimethoxyindoles to beused for conversion into carbolines and diazines related to harmineand harmaline.The 2 : 5- and 3 : 4-dimethoxyphenylhydrazineswere, however, obtained, of which the latter, by condensation with(a) cyclohexanone and (a) ethyl pyruvate, furnished 6 : 7-dimethoxy-1 : 2 : 3 : 4-tetrahydrocarbazole and ethyl 5 : 6-dimethoxyindole-2-carboxylate, respectively. Both these substances gave the“ brucine reaction ” with nitric acid, thus affording some supportfor the view that in brucine the two methoxyl groups are in theortho-position.lsIsatin.-There has been considerable activity in the preparationand study of derivatives of isatin, some of which have found applic-ation in medicine. Although these new substances are importantin many ways, they are not of sufficient general interest to warrantdetailed a t tent ion here.About 1840, Laurent and Erdmann independently studied theaction of ammonia on isatin under various conditions and isolateda number of compounds to which several investigators have recentlydevoted attention.A. R’eissert and H. Hoppmann l9 find thatLaurent’s “ isatinammonia ” is 3-arnino-3-hydroxy-2-ketodihydro-indole (I) and is the primary product of the reaction. Isatin-3-imide (11) (Laurent’s “imesatin ”) is formed when ammonia ispassed into the suspension until the isatin is just all dissolved, whilstthe prolonged action of ammonia on isatin, suspended in alcohol,produces Laurent’s “imasatic or isamic ” acid (111), which is3-isatinimidyl-o-aminomandelic acid.If alcohol is replaced bywater as the suspending medium, the same substance is formedalong with Laurent’s “ imasatin,” which is regarded as 3-isatin-imidyl-3-dioxindole (IV), since it can be synthesised by warmingisatin with isatinimine in alcohol. “ Amasatin ” or ‘‘ isamide ” issimilarly shown t o be 3-isatinimidyl-o-aminomandelamide (V),NH~~~:>c:N.c(oH)(co,H).c,H,.NH, (111.)N H < ~ ~ ~ ~ c : N . c ( o H ~ < - ~ ~ ~ N H (IV.)NH<~~::>C:N.C (OH) (co-NH,).c,H,-NH, (v. 1It has also been shown that Laurent’s “ isatan ” (Erdmann’s“ isatide ”), obtained by reducing disulphoisatide with ammoniuml9 Ber., 1924, 57, 972; A , , 1924, i, 874.*@ A. Wahl and W. Hansen, Compt. rend., 1924, 178, 214, 393; A., 1924,Compare J ., 1925,127, 1161.i, 322164 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.hydrogen sulphite, is represented by LefBvre’s formula 21 (I) andyields, when boiled in naphthalene solution, indine which has beenshown by various workers 22 to be identical with isoindigotin (11).Laurent’s (‘ isatide ” has been obtained by several investigatorsby the reduction of isatin and is represented by Lefhe’s formula 23(111) ; it is not converted into indine by boiling naphthalene.Disulphoisntide is the sulphur analogue of this, with the *OHgroups replaced by .XH groups. L. Sander 22 suggests that Laurent’s(‘ sulphisatide,” produced by the action of hydrogen sulphide on a,cold alcoholic solution of isatin, is 3-thioloxindole and states thatit is converted by cold alcoholic sodium hydroxide into indine (iso-indigotin), which in turn is transformed by warm alcoholic soda intoLaurent’s (‘ hydrindine.” The latter is identified as hydroxy-dihydroisoindigotin, to which formula (I) was assigned by P.Fried-kinder and L. Sander.23 It therefore appears that “ isatan )’ and(‘ hydrindene ” may be identical. It should be added that theN-amino-derivative of the substance represented by (I) has beenprepared by P. W. Keber and H. Keppler 24 by condensing 1-amino-oxindole with isatin in alcohol.Indigotin.-Some discussion has taken place regarding the variousmodifications of the Baeyer formula for indigotin (I) that have fromtime to time been put forward. W. Madelung and 0. Wilhelmi 25have pointed out that although the imino- and carbonyl groups ofindigotin are not readily responsive to the usual reagents, thepresence of the carbonyl groups can be made manifest by the use ofsuch reagents in the case of di-iminoindigotin 26 (11) and from the21 L.Lefbvre, Bull. SOC. china., 1910, [iv], 19, 113; A., 1916, i, 430. Forsimilar compounds of 7-methylisatin, see A. Wehl and T. Faivret, Compt.rend., 1925, 180, 589, 790; A . , 1925, i, 588; A,, 1926, 79; Ann. Chin&., 1920,[XI, 5, 314; A., 960.12 L. Lefbvre, EuZE. Roc. chi7?t., 191G, [iv], 19, 111; A , , 1910, i, 430; corn-pare L. Sender, Bep., 1928, 58, 820; A., 1925, i, 977.23 Ber., 1924, 57, 648; A., 1924, i, 662.24 Ibid., p, 778; A., 1924, i, 761.2 5 Ibid., p.234; A., 1924, i, 422; compare, however, Thiele and Pickard,26 W. Madelung, ibid., 1913, 48, 2259; A . , 1913, i, 903,ibid., 1898, 51, 1252; A., 1898, i, 493ORGANIC CHBWSTRY.-PART In. 165latter it is possible to prepare indigotindioxime 27 and other similarderivatives by the use of the usual reagents. The stability ofindigotin also suggests some sort of connexion between the carbonyland the imino-groups and lends support to such formulse as thoseproposed by M. Claasx 28 (111) and by I. Lifsohitz and H. Lour% 29(111.) ( IV. )(IV), which only differ on the point of representing the connexionin question by rigid bonds or by residual affinities. Such formulsare not readily applicable to the dioxime, bisphenylhydrazone, etc.,of indigotin, although these derivatives are closely related opticallyto indigotin itself.Madelung and Wilhelmi therefore prefer aformula of the type developed by Scholl 3O (V) or the modified form(VI), which has the advantage that it is also applicable to thio-indigo and oxindigo, where the :NH group is replaced by the singleatoms S and 0 so that the co-ordinating hydrogen atom shown in(V) is not available. Formula (V) and (VI) have the furtheradvantage that they account for the absence of cis- and trans-isomerism in indigotin, which is required by the Baeyer formula,although some workers have specified a preference for either thecis- 310 or trans- 31b form as representing ordinary indigotin, a t leastin some of its reactions. On this particular point, R.Robinson32has put forward the formula (VII) or its extension (VIII), which also(VII.) (VIII.)satisfactorily accounts for the absence of a second form. A newformula in detailed (IXa) and simplified (1x6) forms has also been*’ Annulen, 1914, 405, 58; A., 1914, i, 738.2 8 Ber., 1916, 49, 2079; A . , 1916, i, 839.** Ibid., 1917, 60, 897; A , , 1917, i, 580.Georgievio’s ‘‘ Die Beziehungen zwiachen Farbe und Konstitution vonParbstoffen,” 1920. Compare T. M. Lowry, J. SOC. Chem. Ind., 1925,44,230.31 See, for example, ( a ) K. G. Falk and J. M. Nelson, J. Amer. Chem. SOC.,1907, 29, 1739; A., 1908, i, 107; (b) T. Posncr and W. Kemper, Ber,, 1924,57, 1311; A., 1924, i, 1237.J. Soc. Dyers Col., 1921, 37, 77156 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.suggested by H.King 33 based on the J. J. Thomson formula forbenzene, which accounts a t least as well as anything yet suggestedfor the various anomalies referred to above.CH CO CO CHPyridine Dericatives.A comparatively simple method of obtaining pure pyridine hasbeen described, depending upon the preparation of the perchlorate,which is much less soluble than those of the bases usually accom-panying pyridine in the commercial product.34A fuller account has now been given of the degradation of pyridineto gl~tacondialdehyde.~~ Pyridinium-1-sulphonic acid (I), obtainedby the action of various sulphonating agents on pyridine in carbontetrachloride, on treatment with cold concentrated sodium hydroxidesolution, yields the disodium derivative of u-imino-r-hydroxy-AB8-pentadiene-N-sulphonic acid (111, which is hydrolysed by warmalkalis to the sodium derivative of enolic glutacondialdehyde (111).g=g:0 p=pxGH F + RH-RHNaO*CH N(S0,)oONa NaOeCH YH YH so2 + CH=N<O(1.1 (11.1 (111.)The inverse process of building up pyridine and its derivativeshas also received some attention. L. E. Hinkel and W. R. Made1have observed that the substitution of a bromine atom or a nitro-group in position 3 in p-dimethylaminobenzaldehyde leads to anincreased yield of the dimethyldihydropyridine derivative obtainedin Hantzsch’s condensation pr0cess.~8Carbazide (or azoimide) dissolved in benzene and heated to 150ein a closed vessel produces pyridine and if the pressure be maintaineda t 6 to 7 atmospheres during the process some aniline also is formed.With toluene the products are y-picoline and toluidine and withp- cymene , carvacrylamine and 2-met hyl- 5-isoprop ylpyridine ?33 J.SOC. Chem. Ind., 1925, 44, 135, 285; compare Lowry, Zoc. cit.34 F. Amdt, A. Kirsch, and P. Nachtwey, Ber., 1926, 59, 1074; A., 843.35 P. Baumgarten, ibid., 1926, 59, 1166; A., 844; compare Ann. Report.9,38 J., 1926, 161; A,, 413.37 T. Curtius and A. Bertho, Sitzungsber. Heidelberg. Akad, Wies., A , , 1924,3; 1925, 3; A., 1926, 1152.1924, 21, 125ORGANIC CHEMISTRY.-PART m. 157When a solution of acetone, formaldehyde, and methylamine hydro-chloride is boiled for 8 hours, racemic a- and p-forms of 4-hydroxy-3-aoetyl- 1 : 4-dimethylpiperidine are producedF8 On oxidation withbarium hypobromite, both are converted into the 3-carboxylic acids(IV), which are of interest owing to their partial similarity to ecgonine(V) in structure and to the fact that, like the latter base, they yieldlocal anaesthetics on benzoylation, followed by esterification withmethyl alcohol.FH,-YH*CO,H CH,-~H-~H*CO,H(IV.) NMe 'Me-OH 1 YMe yH.OH W.1bH2--kH2 CH,-C H-CH,It has been assumed hitherto that the condensation of isovaler-aldehyde with ammonia in presence of alumina gave as sole product3 : 5-diisopropyl-2-isobutylpyridine, but it now appears 39 that twoother bases are also formed, (a) 3 : 5-diisopropyl-4-isobutylpyridineand (6) 3 : 5-diisopropylpyridine. A series of alkylpyridines hasalso been made by the action of organo-magnesium halides ona-piperidino-nitriles, the cyanogen group of the latter being replacedby the alkyl radical of the magnesium compound.40Contrary to the experience of H.Meyer 41 that 2- and 4-pyridonesdo not acylate, A. E. Tschitschibabin and co-workers have beenable to prepare benzoyl and pnitrobenzoyl derivatives of 2-pyridone,and also an acetyl derivative, which, however, is only formed inthe absence of water.42 Among other investigations on derivativesof pyridine, reference may be made to a number of papers on 2-, 4-,and 2 : 5-aminopyridines and on hydrazo- and azo-derivatives ofpyridine,M which contain much useful information but cannot bedealt with here in the necessary detail to be of value. Nitrationexperiments with 2-, 3-, and 4-phenylpyridines show that the pyrid-inium residue has mainly a para-directive effect, although in thecase of 2- and 4-phenylpyridines a considerable amount of m-nitr-C.Mannich, with G . Ball and L. Stein, Arch. Pharm., 1926, 264, 65, 77;80 (Mlle.) M. P. Oparina, J . Russ. Phys. Chem. SOC., 1925, 57, 319; A., 1926,A. E. Tschitschibabin andA,, 522, 523.844; compare H. Ljubavin, A., 1873, 1023;co-workers, A , , 1906, i, 451; 1923, i, 1121, 1122, 1123.M. Velghe, Bull. SOC. chim. Belg., 1926, 35, 229; A., 1044.I1 Monalah., 1905, 26, 1303; A . , 1906, i , 107.It J . Ruse. Phys. Chem. SOC., 1925, 56, 153; A., 1926, 179; Ber., 1925, 58,2650; A., 1926, 179.A. E. Tschitschibabin and others, Ber., 1926, 59, 2048, 2055; A., 1153;J .Ruae. Phye. Chem. SOC., 1926, 57, 297, 301; A., 845; L. Sohmid and B.Becker, Monatsh., 1926, 46, 671, 675; A., 845.E. Konigs and others, Ber., 1925, 58, 2571 ; 1926, 59, 316, 321 ; A.,178,412, 413188 ANNUAL REPORTS ON THE PROGRESS OF OHEMISTRY.ation occurs.45 The carboxyl groups in potassium collidine-3 : 5-dicarboxylate are not replaced by nitro-groups on heating withnitric acid up to 200'. Nitration of collidine itself with nitrio andfuming sulphuric acids produces 3-nitro-2 : 4 : 6-trimethylpyridine.QsQuinoline Croup.J. Meisenheimer and E. Stotz,47 after a critical survey of theliterature of the dihydroquinolines, conclude that the substancesprepared by M. X'reund and E. Speyer 48 by the action of organo-magnesium halides on quinoline methiodides are, as then suggested,1 -methyl-2-alkyl-l : 2-dihydroquinolines, showing but little tendencyto polymerise, except in the case of the 2-phenyl derivative.Asecond group made by G. Heller and ~o-workers,~~ by reductionwith zinc dust of the pseudo-bases precipitated from solutions ofquinoline methiodides by sodium hydroxide, are bimolecular andwere assigned formula (11)) mainly on the ground that identicalproducts were obtained by the reduction of Freund's bases (I), thenascent hydrogen being assumed to catalyse polymerisation. Itis suggested as more likely that Heller's process produces firstunstable 1 : 4-dihydro-compounds, which then polymerise, with theformation of a new tetramethylene ring (111).(1.1 (11.) (111.)The third group described by R5ith,50 as produced by the actionof halogenoacetals on toluidines, is not, as assumed by that author,identical with Freund's bases and, according to W.Konig and R.B ~ c h h e i r n , ~ ~ the chief product of the action of chloro- or bromo-acetal on o-toluidine is 4-ethyl-o-toluidine. In this oonnexion,it is interesting to note that F. A. Mason 52 has found, on re-examin-ation of his product, that it is 2-methylquinoline and not 1 : 2-di-hydroquinaldine. Similarly, the " 4-keto-2-methyl-1 : 4-dihydro-4 b R. Forsyth and F. L. Pyman, J., 1926, 2912; compare this Report,4 6 P. J. van Rijn, Rec. trav. ehim., 1926, 45, 267; A,, 525.4 7 Ber., 1925, 58, 2330; with K. Bauer, 2320; A,, 1926, 76.4 * Ibid., 1904, 37, 4666; A., 1905, i, 156.48 Ibid., 1914, 47, 2893; A., 1915, i, 300; compare W.If. Mills 4nd R.Raper, J., 1925,127, 2466; A., 1926, 7 7 ; E. Rosenhauer, H. Hoffmann, A.Schmidt, and H. Unger, Be?., 1926, 69, 946, 2356; A., 735, 1260; and Ann.Repwte, 1923, 20, 151 ; 1925, 22, 143.p. 175.60 Ber., 1924, 57, 550, 715; A., 1924, i, 555, 667.61 Ibid., 1925, 58, 2868; A,, 1926, 178.6z J., 1926, 955; compare J., 1925, 127, 1032ORGANIC CHEMISTRY .-PART m. 169quinoline ) ) obtained by G. Heller and A. SourLis 53 by the reductionof 0-nitrophenylhydroxyethyl methyl ketone with zinc dust andcold 33% acetic acid is, according t o J. Meisenheimer and E. Stotz,2-methylquinoline N-oxide, and similar N-oxides have been pre-pared from pyridine and is~quinoline.~~E.Rosenhauer and H. Hoffmann49 have prepared three moreexamples of the crystalline 2-methylenedihydroquinoline basesreferred to last year. These were obtained by the cautious additionof dilute sodium hydroxide solution to aqueous solutions of 2-methyl-,2 : 4-dimethyl-, and 2 : 4 : 6-trimethyl-quinoline methosulphate(methiodide in the latter two cases), followed by immediate extrac-tion with ether. This process is practically identical with Heller'smethod of obtaining '' methyldihydroquinolines " and probablyexplains some of the anolualies referred to in the discussion by Meisen-heimer and Stotz referred to above. J. E. Humphries also hasfound that the interaction of 2-methylquinoline and allied bases ortheir quaternary salts with 4 : 4'.tetramethyldiaminobenzhydrol inpresence of acetic acid affords another instance of the anomalousreactivity of the 2-methyl group in heterocyclic compounds.554-Methoxy-2-methylquinoline condenses under ordinary conditionswith aromatic aldehydes to produce the corresponding 4-methoxy-2-styrylquinolines, but if the reaction takes place under pressure,wandering of the methyl group occurs and some of the corresponding2-styryl-1-methyl-4-quinolone is also formed.Piperonal is excep-tional in giving only one product, the alkaloid dehydro~usparine.~~A normal condensation also takes place between m-nitrobenzalde-hyde and 2-methylquinoline, the sole product being 2-m-nitrostyryl-q~inoline.~'A series of amino-derivatives of styryl- and anil-quinolines hasbeen prepared for bactericidal examination.Of the two series,the styryl derivatives are the more powerful antiseptics and as arule the potency is increased by methylation or acylation of theamino-group, sulphonation or other methods of increasing the soh-bility, or the introduction of a further condensed nucleus. TheBtyryl side-chain is less effective in position 4 than in position 2,and acidic groups in position 6 lower the activity, which is completelylost with an azo-group in this position.58bs Ber., 1908, 41, 2692; A , , 1908, i, 913.6 4 Ibid., 1925, 58, 2334; 1926, 50, 1848; A., 77, 1152.6 6 J . , 1926, 374; A., 414.6 8 J. Troger and E. Dunker, J. ;or. Chent., 1926, [ii], 112, 196; A,, 525;s 7 T. W. J. Taylor and C. P. Woodhouse, J., 1926, 2971; compare W.68 0.H. Browning, J. B. Cohen, S. Ellingworth, and R. Gulbrmsen, PTOC.compare Ann. Reports, 1924, 21, 131 ; 1925, 22, 142.Wartanian, Ber., 1890, 23, 3648; A., 1891, i, 329.Roy. Soc., 1926, [B], 100, 293; A., 1153160 ANNVAL REPORTS ow THE PROGRESS OF CHEMISTRY.Naphthaquinolines of two types, angular (I) and linear (11),are known to be produced simultaneously by the application of theSkraup reaction to ar-tetrahydro-p-naphthylamine.59Both types are also formed in the quinaldine synthesis with eitherar-tetrahydro-a- or -p-naphthylamine 60 and the course of the reac-tion has been investigated in the latter case. A nearly quantitativeseparation of the two p-isomerides can be effected through thehydriodides, that of the alzg.-isomeride being almost insolublewhen precipitated in dilute hydrochloric acid. The total yield ofthe crude mixed bases is 35% of the theoretical, of which 65% isthe angular isomeride (3-methyl-7 : 8 : 9 : 10-tetrahydro-p-naphtha-quinoline, Type I), the remainder being the linear base (%methyl-6 : 7 : 8 : 9-tetrahydro-a-anthrapyridine, Type 11). From thesedata, it is concluded that the tetramethylene group in ar-tetrahydro-p-naphthylamine, used as a primary material in the quinaldinesynthesis, has no directive influence in the formation of the thirdring and that the energy content determines which isomeride willbe formed. The energy content of the four systems is in the order(III)>(IV) and (VI)>(V). Systems (111) and (V) should yieldlinear, and systems (IV) and (VI) angular tricyclic compounds.The energy difference between (V) and (VI) is so marked thatp-naphthylamine gives angular compounds exclusively.The differ-ence between (111) and (IV) is less marked, hence a mixture of iso-merides is formed with the angular form predominant in the caseof ar-tetrahydro-p-naphthylamine.A number of naphthaquinoline and naphthaisoquinoline deriv-atives have been prepared by C. 8. Gibson, K. V. Hariharan, K. N.Menon, and J. L. Simonsen.61 The condensation of @-naphthyl-amine with paraldehyde 62 was found to proceed smoothly (to dl-1-methyl-1 : 2 : 3 : 4-tetrahydro-P-nt1,phthaquinoline as a h a 1 pro-69 J. von Braun and H. Gruber, Ber., 1922,55, 1710; A . , 1922, i, 762.$0 J.Lindner and others, Monatsh., 1924, 44, 337;A , , 1924, i, 1102; A., 1926, 410.61 J . , 1926, 2247; A., 1154.6z 0. Doebner and W. von Miller, Ber., 1884, 17, 1711 ; A., 1884, 1373.1925, 46, 226, 231ORGANIC CHE,PISTRY.-PbRT III. 161duct, through 3-chloro-l-methyl-P-naphthaquinoline as describedbelow), but 2-methyl-a-naphthaquinoline could not be obtained bycondensing a-naphthylamine with paraldehyde as described byDoebner and von Miller and recourse was had to st modification ofKnorr's method,e viz., condensation of a-naphthylamine withethyl acetoacetate, the new feature being the use of diethylamineas a catalyst. By this means, ethyl p-1-naphthylaminocrotonate(VII) was obtained, which on heating a t 240" was converted into4-hydroxy-2-methyl-a-naphthaquinoline (VIII), and this yielded(El-2-methyl-1 : 2 : 3 : 4-tetrahydro-a-naphthaquinoline (IX) bytreatment with phosphorus pentachloride followed by reductionof the 4-chloro-derivative with sodium and ethyl alcohol.CMoNHCMe:CH*CO,Ef '*'/ .. AUnder the conditions prescribed by Knorr,63 the main productis 8-di-a-naphthyl~arbarnide,~~ accompanied by some p-1-naphthyi-aminocrotono-a-naphthylamide (X) ; the latter can be hydrolysedto acetoaceto-a-naphthalide (XI), which can with daculty beinduced to undergo ring closure t o 2-hydroxy-4.methyl-a-naphtha-quinoline (XII). From this, the corresponding tetrahydro-deriv-ative can be made through the chloro-compound as described above.C*OHThese dficulties in the use of a-naphthylamine as a primarymaterial in the synthesis of naphthaquinolines are not encounteredin the case of the 4-nitro- and 4-bromo-a-naphthylamines, whichreadily condense with paraldehyde, furnishing the corresponding6-nitro- or 6-bromo-2-methyl-~-naphthaquinoline. The importanceof substituents in position 4 in facilitating condensation with par-aldehyde is emphasised by s.U. Nair and J. L. Simonsen in a laterpaper describing the preparation of a series of acenaphthpyridines.65Comparatively little work has been done during the year onnaturally-occurring quinoline bases. It has been shown that theL. Knorr, Ber., 1884,1?, 543; A . , 1884, 1198; compare M. Conrad andL. Limpach, ibid., 1888, 20 531; A., 1888, 503.I4 Compare (Miss) W. G. Hurst and J.F. Thorpe, J . , 1916, 107, 934.66 J . , 1926, 3140.REP.-VOL. XXIII. 162 ANNUAL REPORTS ON THE PROGRESS OB CHEMISTRY.B-acid formed by the hydrolysis of oryzanin from rice is 2 : 6-di-hydroxyquinoline-4-carboxylic acid.6s No success attended attemptsto introduce arsinic acid residues into diazotised solutions of variousamino-derivatives of reduced cinchona alkaloids,67 but arsino-derivatives of phenylcinchoninic acid can be so made 68 and arecapable of reduction to arseno-compounds. By the use of arsenictrichtoride on dehydroquinine, the arsenical compound (I; Q =the quinolyl and Q = the quinuclidine nucleus) 69 is produced, Ontreatment with ammonium carbonate solution, one of the arsenicgroups is lost with the formation of chloroarsinosoquinine (11).With quinine and dihydroquinine the compounds C2,H2,02N2CI,RsAsCl,*CH:CCl*Q’(HCl) *CH( O*kSCl,)*Q( OMe) ,HCl @S action of-f (1.1 ammonium carbonate)AsO*CH:CCl*Q’*CH(OH)*Q.OMe (11.)and C,,H2,0,N2C1,As are formed ; these are converted by ammoniumcarbonate solution into the arsenious esters, C,,H,,O,N& andC,,H~O,N,As, which contain the arsenic atom united to the secon-dary alcohol group thus, -CH*O.AsO.isoQuinoline Group.What is regarded as the trans-form of decahydroisoquinolinehas been prepared by L.Helfer 70 from trans-o-carboxycyclohexane-acetic acid 7 1 by converting the latter into its imide and reducingthis with sodium and boiling amyl alcohol. Reduction of thelactam of o-p-aminoethylphenylacetic acid by sodium and ethylalcohol produces a mixture of bases from which 8-homotetrahydro-isoquinoline (I) was isolated with 0- p’-aminoethyl- p-phenylethylalcohol, NH,*CH2*CH,*C6H4*CH2-CH2.0H, as a by-pr0duct.7~C6H4<g2:g2>m ae 3:(1.1 (11.) (In.)68 Y.Sahaehi, Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1926, 4, 207;6 7 F. X. Erben, E. Philippi, and 0. Maulwurf, Bey., 1926, 59, 2150; A,,a* H. 0. Calvery, C. R. Noller, and R. Adams, J. A m r . Chem. Soc., 1925,60 F. X. Erben and others, Bey., 1925,68, 2854; A., 1926, 188.70 Hclv. China. Acta, 1926, 9, 814; A,, 1150. For cis-form, see ibid., 1923,‘1 A. Windaus, W. Hiickel, and G. Reverey, Bey., 1923, 56, 91; A., 1923,7 1 J. von Braun and H. Reich, Annulen, 1925, 445, 225; A,, 1925, i, 1406;A., 846.1169.47, 3068; A,, 1926, 187.6, 785; A., 1923, i.1228.i, 220.Bey., 1925, 58, 2765; A,, 1926, 176ORGANIC CHEMISTRY.-PART KU. 163It has been found feasible to prepare naphthaisoquinolines 61by the application of a method 73 used by Kaufmann and Radosevibfor the preparation of simple isoquinolines, which depends on treat-ment of the oximes of y-ketobutylbemenes with phosphorus penta-chloride. a- and p-Naphthaldehydes condense readily with acetoneto give 1- and 2-y-ketobutenylnaphthalenesJ C,,H,.CH:CH*COMe,which on catalytic reduction furnish y-ketobutylnaphthalenes,C,,,H7~CH,~CH,~COMe ; from the oximes of these, 4-methyl-1 : 2-dihydro-P-naphthaisoquinoline (11) and 1-methyl-3 : 4-dihydro-a-naphthaisoquinoline (111) , respectively, were obtained althoughin small yield.This year's work includes many important papers on alkaloidsof this group.These alkaloids belong to three types : (A) benzyl-isoquinolines with a sub-section of meconylisoquinokes ; (B) di-isoquinolines, including alkaloids such an cryptopine, developedfrom i t ; and (C) the phenanthrenoisoquinolines with morphineand the related alkaloids, codeine and thebaine, as a sub-section.Means of converting type (A) into type (B) or (C) are now well known.Benzytisoquinolines.-A considerable number of these productshave been prepared in preliminary attempts to synthesise (1)members of the diisoquinoline or berberine group of towhich reference has been made in the last two Reports of this series,and (2) representatives of the phenanthrene group of isoquinolinealkaloids to whioh attention is directed later in this Rep0rt.~6The formation of N-oxides when heterocyclic bases and alkaloidsare treated with hydrogen peroxide, perbenzoio acid, and similaroxidising agents is now well known.A. M. Drummond and A.McMillan '13 have prepared a derivative of this type (I) from nar-cotine, the reactions of which indicate that it is a true N-oxidein which the structure of narcotine is preserved. It yields a crys-talline hydrochloride which contains a free carboxyl group, andis therefore represented by (11), and is readily hydrolysed to a hydr-oxy-acid, from which the hydrochloride can be regenerated, and forwhich the betaine structure (111) is suggested.Me $?H Me YH Me YH\OH(11.1 VH*OHj/L k? $/&e<:lH $ / w e(I.) p j j c o v=-o (\)CO,H 1 (jCO.0 \Be?., 1916, 49, 675; A ., 1916, i, 502.R. D. Haworth and W. H. Perkin, jun., J., 1925,137, 1434; A., 1926,i , 968; R. D. Haworth, W.H. Perkin, jun., and J. Rankin, W., p. 1444;A . , 1925, i, 969; Ann. Regort8, 1924, 21, 133; 1926, %, 146.76 R. Robinaon and (Miss) H. West, J., 1926, 1986; A,, 1046.J . , 1926, 2702; A., 1263164 ANNUAL REPORTS ON THE PROQRESS OF OHEMISTRY.Mention was made last year 77 of the proof by E. Spiith andco-workers that the alkaloid tritopine is merely impure laudanidineand that, since the latter is converted into 1-laudanosine by diazo-methane, whilst laudanine on similar treatment yields dl-laudan-osine, and both on ethylation and oxidation of the ethyl etherfurnish 4-methoxy-3-ethoxybenzoic laudanidine must bethe laevo-form of laudanine.This year the same investigators,continuing this work on the minor alkaloids of opium, have shownthat pseudopapaverine, to which 0. Hesse assigned the formulaC,,H,,O,N, is merely impure papaverine, C,,R,,O,N, and thatKonig’s methylenepapaverine, C,,H,,O,N, obtained by the con-densation of papaverine with formaldehyde, yields papaveraldineon oxidation, takes up two atoms of hydrogen to form a dihydro-derivative, and therefore must have the constitution shown below.79Similarly, they have found that codamine, C,,H,,( OH)( OMe),N, onmethylation furnishes d-laudanosine, but on ethylation and oxidationof the ethyl ether, 3 : 4-dimethoxybenzoic (veratric) acid wasobtained, so that in this case the free hydroxyl group of codamine,represented by the ethoxy-group in the ethyl ether oxidised,, mustbe in the quinoline and not in the benzyl nucleus.Codamine there-fore is not Llaudanidine. The second product of the oxidationproved to be the mixed methyl and ethyl ether of nor-m-hemipinicacid, which leaves it certain that the free hydroxyl group of codamineoccupies either position 6 or 7 in the isoquinoline nucleus. Thedecision in favour of position 7 was reached by (1) discovering theconditions under which dl-laudanosine could be oxidised to N-methyl-corydaldine, a substance which has been synthesised and aboutwhose constitution there is no doubt, (2) synthesising the two mixedethers (ethoxy in 6 or 7, methoxy in 7 or 6) corresponding t o N -methylcorydaldine, and (3) oxidising the ethyl ether of codamine(a homolaudanosine) under the conditions determined in (1) andidentifying the ‘‘ corydaldine ” produced with one of the mixedethers referred t o under (2).The product in question proved tobe 6-methoxy-7-ethoxy-N-methylcorydaldine 8o (I below).In early attempts to synthesise laudanine, H. Decker and T.Eichler 81 obtained an isomeride, pseudolaudanine, which theyregarded as a laudanosine in which one of the four methoxyl groups,and probably one in the isoquinoline nucleus, is replaced by hydroxyl.This speculation brings pseudolaudrtnine into close relationship7 7 Ann. Repwte, 1925, 22, 152.7s E. Sp&th [withR.Seka], Ber., 1925,68, 1272; A . , 1925, i, 1093; [with7e E. Spiith and N. Polgar, Be?., 1926, SQ, 2787.*O E. Spiith and H. Epetein, ibid., p. 2791.B1 Annden, 1913, 395, 377; A., 1913, i, 289.E. Bernhauer], ibid., p. 200; A., 1925, i, 294ORGANIC CHEMISTRY .-PART III. 165with codamine, since it would be either cU-codamine, or the latterwith the positions of the hydroxyl and methoxyl groups in the is0-quinoline nucleus interchanged. The letter is now found to statethe relationship correctly since, by the process outlined above, ityields on oxidation 7-methoxy-6-ethoxy-N -methylcorydaldine(compare I below), The foregoing proofs rest on the correct for-mulation of laudanosine and laudanine, both of which have beensynthesised by methods which leave no doubt of their constitution."The inter-relationships of these bases may be represented as follows :CH2 CH2 CH2YHt MeOf)OC€& e --f Me04 M e O / D , NMe+ Ho\A./4,)IOMe !\,,,,).MeOMe OMeLaudanosine.Lauhnine, lazcdanidinc(tritopine) .By ethylationand oxidation.OMe OMe OMePapaverine Methylenepapaverine.( pseudopapavevine).Diisoquinoline Allcaloids.-The transition from the benzyliso-quinolines to the diisoquinolines is effected by the insertion of itCH, group between positions 2 and 2' (berberine series) or 2 and 6'(pseudoberberine series), the latter being the position usually takenup in the direct synthesis of such products, and in attempts tosynthesise the natural alkaloids of this type it has been necessaryto build up the heterocyclic ring of isoquinoline as in the synthesisof oxyberberine effected recently.83 On the same lines, substanceRda A.Pictet and (Mlle.) M. Finkelstein, Compt. rend., 1909, 148, 925; A , ,1909, i, 323; E. Spath and N. Lang, Moltatah., 1921, 42, 273; A., 1922,i, 56%Codamine with -0Me and -OH interchanged = pseudoleudenine.8 3 Compare Ann. Reporte, 1924, 21, 133; 1925, 22, 146166 ANNUAL REPORTS ox THE PROGRESS OF CHEMISTRY.allied to oxyberberine have been obtained 84 by condensing homo-piperonylamine (I) with homophthalic acid and with 4 : 5-dimeth-oxyphthalic acid (II), producing in the latter case 2-homopiper-ony1.6 : 7-dimethoxyhomophthalimide (1111, which is converted byd ~ ~ l i a into the'corresponding amic acid, the methyl ester of whichon dehydration yields oxypseudoberberine (IV).(11.) CH, ?T::cq: NH2+2 CH2The condensation with homophthalic acid gives rise in like mannerto 2-homopiperonylhomophthalimide (V), but in this case the methylester of the corresponding amic acid, on treatment with phosphorusoxychloride, yields two products, 2 : 3-methyIenedioxyoxyproto-berberine (yI) and 2 : 3-methylenedioxyoxyisoprotoberberine (VII).Further work has also been done on the Corydalis alkaloids.The method described last year 85 for the conversion of berberineinto palmatine and jatrorrhizine has been applied t o d-, 2-, andd2-tetrahydroberberines and has furnished the corresponding d- , 1-,and dl-tetrahydropalmatines.86 The constitutions assigned t ooorybulbine and isocorybulbine 87 have been con6rmed by inde-pendent work 88 and by their simultaneous formation by the partialdemethylation of oorydaline 89 by heating this for a short time with'( R.D. Haworth, W. H. Perkin, jun,, and H. S. Pink, J., 1925,127, 1709;A , , 1926, i, 1168.Ann. Reports, 1925, 22, 151.a * E. Spgth end E. Mosettig, Ber., 1926, 59, 1496; A., 965.e.' Ann. Reports, 1925, 22, 150.a@ E. Spiith and H. Holter, Ber., 1926, 59, 2800.J. Gadamer and K. Sawai, Arch. Pharm., 1926, 264,401 ; A,, 1161ORGAWC CHEMISTRY.-PART m. 167hydrochloric acid. From calumba root, E. Spiith and G. Burger 90have isolated a new alkaloid, tetrahydrooolumbamine,which is converted by diazomethane into dl-tetrahydropahatine andby diazoethane into a monoethyl ether, which on oxidation yields,like isocorybulbine, 6-methoxy-7-ethoxy-1-keto-1 : 2 : 3 : 4-tetra-hydroisoquinoline and must therefore have the constitution (VIII).C,,H,,WH)(OMe),,OHBerberrubine g1 and palmatrubine 92 are produced by heatingberberinium and palmatinium chlorides, respectively, and both havebeen regarded as similarly constituted, since they are reconvertedinto the iodides or other salts of the parent alkaloids on treatmentwith methyl esters, It has now been found that tetrahydro-berberrubine ethyl ether on oxidation furnishes hydrastic acid and4-methoxy-3-ethoxyphthalic acid, whilst tetrahydropalmatrubineethyl ether yields rn-hemipinic acid and 4-methoxy-3-ethoxyphthalicacid.Berberrubine and palmatrubine are therefore regarded asphenol-betaines (IX) in which the positions marked * are occupiedby a dioxymethylene group and two methoxy-groups, respective1y:OCoptis japonim has been shown by Z.Kitasato 93 to contain anew alkaloid, coptisine, C,,HIBO,N. This is regarded as 2 : 3 : 9 : 10-bismethylenedioxyprotoberberine (X),@* since by the prolongedaction of phloroglucinol and sulphuric acid it is converted, by lossof two dioxymethylene groups,95 into an unstable phenolic base,which on methylation and reduction furnishes tetrahydropalmatine.This alkaloid is closely related to a series of products prepared byR. D. Haworth and W. H. Perkin in the course of their synthesis90 Ber., 1928,59,1488; A,, 963; and compare Ann. Reports, 1925,22, 151.91 G.Frerichs and P. Stoepel, Arch. Pharm., 1913, 251, 321; A., 1913,i, 1094; I(. Feist and Sandstede, ibid., 1918, 256, 1.02 I<. Ftlist and G. L. Dschu, ibid., 1925, 263, 294; A., 1925, i, 830,9s Proc. Imp. Acad. Tokyo, 1926, 2, 124; A., 1160.94 For nomenclature, see Ann. Reports, 1925, 22. 145.9 5 Compare E. Spath and H. Quietensky, Bey., 1925, 58, 2267 ; A,, 1926, 82168 ANNUU REPORTS ON THE PROQRESS OF CHEMISTRY.of protopine (see below) ; thus the tetrahydro-derivative, m. p. 215",used in the purification of coptisine must be identical with thelatter authors' 2 : 3 : 9 : 10-bismethylenedioxytetrahydroprotober-berine, m. p. 219°.96 Coptisine is also of some biological interest,since all the species of Coptis so far examined are stated to haveyielded berberine.Important contributions have been made during the year to thechemistry of t,he cryptopine section of diisoquinoline alkaloids bythe conversion of berberine into P-homochelidonine g7 (a-ahcrypto-pine) and by the synthesis of cryptopine and p r o t ~ p i n e .~ ~ Theformer transformation was effected by converting anhydrotetra-hydroinethylberberine, by treatment with perbenzoic acid in chloro-form-ether solution below 5", into the amine oxide (XI), which inpresence of acetic and hydrochloric acids isomerises to a-allocrypto-pine (XII).MeOoCH2*NMeG€12*CE2()~>cH~ CH,*COThe final stages in the synthesis of cryptopine (=I) and proto-pine (XIV) have been aobieved by the s&me method, viz., the oxid-ation of anhydrodihydrocryptopine-A (XIIIA) and anhydrodihydro-protopine-A (XIVA), respectively, with perbenzoic acid and isom-erisation of the resulting amine oxides.98Me0 (XII.)(XIIIA.)(XIII.)** J ., 1926, 1780, 178119 7 R. D. Heworth end w. H. Perkin, jun., J . , 1928, 445; A., 417.98 Idem, ibid., p. 1769; A,, 964ORGANIC CHEMISTRY .-PART III. 169The preparation of the initial materials for these final stagesinvolved the discovery of a method for making 3 : 4-methylene-dioxyhomophthalic acidam This was then condensed with p-veratryl-ethylamine to N - 8-veratrylethyl-3 : 4-methylenedioxyhomophthal-imide (XV), and this converted into the corresponding amic acid(XVI), the methyl ester of which was transformed by phosphorusoxyohloride 1 into oxyepiberberine (XVII).OMe OMeOMe .H,C-0 CO CH,The latter was reduced to tetrahydroepiberberine (XVIII),which, on methylation and treatment of the methiodide by silverchloride, furnished the methochloride.This occurs in two separ-able, crystalline forms, identical with the a- and &forms of kodi-hydrocryptopine chloride, either of which on conversion by theusual method yields a mixture of the anhydro-bwes, Viz., anhydro-dihydrocryptopines-A (XIIIA) and -B (XIX) a ; the former of thesewas converted as described above into cryptopine. The synthesisof anhydrodihydroprotopine-A (XIVA) was carried out on analogouslines, the initial condensation being effected between 3 : 4-methylene-dioxyhomophthalic acid and p-piperonylethylamine.o@*iH~-@ vi:hy+&o-CH,. *CH2*CH, OMe -+ (XIIIA.) andH,&O (XVIII.)H,C-0 (XIX.)AU the known diisoquinoline alkaloids, natural or synthetio, are0’ R.D. Hsworthand W. H. Perkin, jun., andT. 8. Stevens, J., 1926,1764;1 Compare this Report, p. 166.1 W. H. Perkin, jun., J., 1918,113, 518; A., 1918, i, 348.A,, 951.a Idem, ibdd., 1916, 100, 938, 941.B 170 ANNUAL REPORTS ON THE PROGRESS 08 CHEMISTRY.of the " angular " type in structure (see formulae above) and it isof interest to record the production of the &st linear form, for theskeleton (XX) of which the name " paraberine " has been coined.*Considerable dificulty was experienced in finding a suitable startingmaterial, but eventually 3 : 4-dimethoxyphenyl 3 : 4-methylene-dioxyatyryl ketone was reduced and converted into the isonitroso-derivative (XXI).This, on reduction with stannous chloride underspecial conditions, gave the corresponding amine, which condensedwith formaldehyde to give 6 : 7-methylenedioxy-3-(3' : 4'-dimethoxy-benzoy1)-1 : 2 : 3 : 4-tetrahydroisoquinoline (XXII). The latter wasoxidbed by iodine to the corresponding unreduced isoquinoline(XXIII), closely resembling papaveraldine in structure and pro-perties. On reduction of this, the corresponding secondary alcohol,which resembles papaverinol, was formed. By electrolytic reductionin hot dilute sulphuric acid of substance (XXIII), a base (XXIV)corresponding with tetrahydropapaverhe was formed and this wasconvertedinto 2 : 3-methylenedioxy-11 : 12-dimethoxy-6 : 15 : 16 : 17-tetrahydroparaberim (XXV) by the action of formaldehyde andhydrochloric acid.This substance exhibits a general similarity in properties to tetra-hydroberberine and its pseudo-isomeride ; unlike these, however,it is not oxidbed by iodine to the corresponding quaternary iodide(berberinium or +berberinium iodide), but is converted into acrystalline hydriodide of an amorphous base, which is 2 : 3-methyl-enedioxy-11 : 12-dimethoxy-6 : 17(or 6 : 15)-rlihydroparaberine.It is suggested that the diEEculty of forming such linear structuresand the small yields obtained may account for the invariable, soR.Campbell, R. D. Haworth, and W. H. Perkin, jun., J., 1926, 32;A., 303ORGANIC CHEMISTRY .-PART m. 171far as present knowledge goes, occurrence of the angular forms innature.Phemnthrenoisoquinolines.-The alkaloid boldine, which has beenknown since 1872, is shown to have the formula C,,H,,O,N.Itundergoes the typical reactions of this type of isoquinoline alkaloid,furnishing eventually 2 : 3 : 5 : 6-tetramethoxy-8-vinylphenanthreneon " exhaustive methylation." It contains two methoxyl groupsand yields a dimethyl ether, which is identical with glaucine (I).Its skeletal structure is therefore certain and it is considered likelythat there is one hydroxyl group in each of the rings 1 and 4.sCH, NMe CH, NMe~ e ~ f ' f ' F i f \ l ~ ~ , 4'- HA HMe0&8H"8H2co 'i" (11.1Me0 FHMeo\/\/\/CH,(1.1 Me*$f ' 1Me \ / C*OHCH, NMeMeO4'V'C6&: "04+,(,?\J' (111.1H2C-Sinomenhe, CIgH2,O4N, appears to offer an interesting varianton the natural alkaloids of this type in containing a.carbonyl groupin the fourth ring. It is converted into methylethylamine andsinomenol, C,,HI4O,, which is regarded as 3 : 4-dihydroxy-5 : 6.di-methoxyphenanthrene, on treatment with 66% potassium hydr-oxide solution. On this and other grounds it is represented byformula (II).6 Of the small group of natural alkaloids of this type,only two, vuiz., glaucine (I) and dicentrine (111), have been synthesisedand the latter has now been resolved into its enantiomorphs.7 Thefinal stage of such syntheses is due to Pschorr * and consists in di.azotising, in presence of copper, the appropriate 2'-aminobenzyl.tetrahydroisoquinoline, and the way was opened for the preparationof a series of the latter materials with the discovery by E.Hopeand R. Robinson that cotarnine and allied bases can be condensedwith 0-nitrotoluene and its derivatives to give o-nitrobenzyItetra-K. Warnst, Ber., 1925, 58. 2768; 1926,69, 86; A, 1926. 185, 311.6 K. Goto, Proc. Imp. A d . Tokyo, 1926, 2, 7, 167; A,, 1160.7 R. D. Haworth, W. H. Perkin, jun., and J. Renkin, J . , 1926, 29; A.,310; compare Ann. Reporta, 1926, 23, 151.8 Eer., 1904, 57, 1926; A., 1904, i, 612. ' J., 1911, 99, 2114172 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,hydroisoquinolines. An instance of the application of these tworeactions waa given last year in the synthesis of aporphine by J.Cadamer, M. Oberlin, and A. Schoeler.10 In a preliminary investig-ation of the possibilities of synthesising a series of these alkaloids,R.Robinson and J. Shinoda l1 have condensed laudaline 1, (I-hydr-oxy6 : 7 - dimethoxy - 2 -methyl - 1 : 2 : 3 : 4 - tetrahydroisoquinoline)with 2 : 4-dinitro-3-methoxytoluene t o give the substance (IV), andCH, NMe CH, NMe/\A&&H2 AcHN /yyyg 0 2 N y & ) \ / k..HN;p$g'#' A/ 1 (V.1 OMe 1 Me0w.1'Y%eMeo\//OMeCH, NMe21WI.) M e 0 0OMeconverted this with difliculty 13 into anhydrolaudaline-2-amino-4-acetamido-3-methosytoluene (V), from which the methiodide (VI)was prepared by Pschorr's process, followed by treatment withmethyl iodide. Replacement of the acetamido-group in this meth-iodide by hydroxyl should give the methiodide of an alkaloid havingone of the formula which have been suggested for iso~orydine.~'blorphine Sub-group.-Of the numerous papers published relatingto morphine, codeine, and thebaine, the two of moat general interestare probably those of J.M. Gulland and R. Robinson Is and of H.Wieland and M. Kotake l6 in which an approximation to an agree-ment regarding the formula to be assigned to codeine and thebaineis perceptible. On the ground that codeine and the methylmorphi-methines show strong evidence of unsaturation,17 the formerauthors now adopt formula (I), whilst Wieland and Kotake suggest10 Ann. Rep&*, 1926, 22, 152.11 J., 1926, 1987; A., 1048.1' F. L. Pyman, J., 1909, 05, 1266.1' Compare R. Robinson and (Mias) H. Weat, J., 1926, 1986; A., 1046.1' J.Qademer, Arch. Pharm., 1911, 249, 503; A., 1911, i, 1011.1s Mm. Manokeeter Phil. Soo., 1924-26, 80, 79; A.,1926, 83.1' Annakn, 1926, 444, 69; A . , 1826, i, 1090; Ber., 1926, 58, 2009; A .l7 See, for example, R. S. Cehn end R. Robinson, J . , 1926, 908; A., 745,1926, i. 1448.which contain8 aleqe, diacussion of the relative merits of formulae (I) and (11)ORGANIC CHEMIBTRY .-PART III. 173formula (11), which d8er.5 from that of Knorr and Horlein is onlyin the removal of the ethylenic linking from Cs-C14 to C,-C,.\4 CH\/ CH(1.) (11.1 (111.)There is, it will be seen, agreement as to the position of thedouble bond at C,-C, and for different reasons on the part of thetwo groups of authors, so that the question may be regarded &E tothat extent simplified.The remaining difference of opinion, thepoint of attachment of the C, ethanamine chain at C, (G. and R.)or C, (W. and K.) requires further experimental evidence for itedecision. C. F. van Duin, R. Robinson, and J. C. Smith ID haveshown that neopine, ClsH210aN, one of the rarer alkaloide ofopium, is a p-codeine, since on hydrogenation it yields dihydro-codeine, whilst it0 methosulphate, on warming with potassiumhydroxide solution, is converted into p-methylmorphimethine (seebelow). Neopine is therefore represented by formula (111),20 whichdiffers from codeine (I) only in the transfer of the ethylenic linkingfrom C,-C, to the more protected position C8-Cl,.The relationships of the six methylmorphimethines have beenre-investigated by E.Speyer and K. Koulen.21 These products areformed by the action of caustic alkali on the methiodides of codeine,isocodeine, allo-+codeine, and +codeine, these bases being them-selves monomethyl ethers of morphine and the a-, p-, and y-Go-morphines, respectively. To theae must now be added neopine(see dove), of which the corresponding " morphine " is unknown.Each of theae codeine methiodides yields a corresponding methyl-morphimethine, some of which are convertible into others by theaction of hot alcoholic potassium hydroxide. These points may besummarised thus :Ber., 1907, 40. 3341; A., i, 789.J., 1926, 903; A., 745.I E Compare formula (VII) for /3-methylmorphimethine (0. and R.).21 Annalela, 1924, 488, 34; A . , 1925, i, 59; compare R.S. Cahn, J., 1926,2562; A., 1264174 m u REPORTS ON THE PROGRESS OF CEEIKISTRY.P r h r y Base -3 Nethyhted Base + MethylmorphirnethinePrimary + SecondaryMorphine Codeinemethiodide a- + p-P-k- alZ0-q [ stable to alkaliyis- q &a-is0 iso- y- * 8-unknown P PThe new results indicate that these six methylmorphimethinescan be arranged in three groups, a- and y- being stereoisomeric andrepresented by formula (IV), E- and 5- also are stereoisomerides(formula V), whilst in p- and 6- the ethylenic linking has moved (VI)from C,-C,, to C,,-C,, (Knorr and Horlein formula). The authorsinterpret their results on the Knorr and Horlein formula, but inpart a t least there is no diEculty in transferring them to the morerecent formula for codeine given above, e.g., p- and 6- methyl-morphimethines would, on Gulland and Robinson’s formula, berepresented by (VII) instead of (VI), whilst from Wieland andKotake’s codeine formula (11) the representation of the p- anda-methines would probably be (VI).(VII.)0HOOH CH\/CH2The other papers, far too numerous to mention here, on alkaloidsof thie sub-group represent a large amount of work, often laboriouORGANIC CHEMISTRY .-PART III.176and not specially fruitful, but which has added much to om h o w -ledge of these interesting substances.Dicmoles.G1yoxalines.-Among the more interesting organia arsenicalcompounds prepared recently are glyoxaIine-4’(or 5’)-carboxy-p-aminophenylarsinic acid (I), and its 3-amino-derivative (NH, at *),prepared by the application of the BarMchmidt reaction toglyoxaline-4(or 5)-carboxy-p-aminoanilide and the correspondingamino-derivative?2 The isomeric o-compound does not couple with(1.) &o~E~GNE*CO*C<CH-NH 9 (11.)N=YH G-CO-Y*\sodium arsenite because treatment with nitrous acid gives rise to asparingly soluble, crystalline diasoimide (11, G = glyoxaline nucleus).2-m- and 2-p-Aminophenylglyoxalines also were prepared andsubmitted, under a variety of experimental conditions, to the Bart-Schmidt reaction, but no arsinic acid was formed, and it is suggestedthat in such cases the conditions favourable for the reaction are alsothose in which the glyoxeline nucleus can couple with the diazo-tised base, leading to the formation of insoluble azo-compounds.2-o-Aminophenylglyoxaline yields a small amount of the triazine(111), whilst 4-p-aminophenylglyoxaline gives a very small yield of4-phenylglyoxaline-p-arsinia acid (IV).A triazine analogous instructure with (111) was obtained from 4-o-aminophenylgIyoxaline.The latter was not resolvable into enantiomorphs through thenormal d-tartrate or the dicamphor-10-sulphonate, an observationof interest in connexion with the current discussion on the represent-ation of diphenyl. So far it has not been possible t o introducearsenic directly into the glyoxaline nucleus.23The determination of the nature of the orienting influence in thenitration of the phenylglyoxalines and their derivatives is stillengaging attention.24.As a result of a, comparative study of thenitration of the benzamidines25 and phenylpyridines,26 it is con-I. E. Balsban and H. King, J., 1925, 127, 2701; A., 1926, 187.23 LOC. cit. and I. E. Bslaban, J., 1926, 569; A., 623.24 Compare Ann. Reports, 1924, 21, 148; 1925, 22, 156.2 6 R. Forsyth, V. K. Nimkrtr, and F. L. Pympn, J., 1926, 800; A,, 611.2 6 R. Forsyth and F. L. Pyrnen, ibid., p. 2912176 ANNUAL REPORT6 ON TEE PROQRESS OR CBEWSTRY.sidered that @ 2-phenylglyoxaline (I) (p-nitration predominant) thedirective factor is the glyoxalinium ion as a whole, which behavesas an aromatic complex and exerts a para-directive influence likethe phenyl group in diphenyl. In 2-phenyl-4 : 5-dihydroglyoxaline(11) (m-nitration predominant), it is suggested that the aromaticcharacter of the glyoxaline nucleus is lost and that the meta-directive influence is exerted by the amidinium ion, also present inthe salts of benzamidine and benzenyltrimethylamidine (111), whichsimilarly nitrate mainly in the m-position.I n the special caseof 2-phenylglyoxaline-4 : 5-dicarboxylic acid (m-nitration pre-dominant), it is believed that the change in directive influence maybe due either to a difference in the influence of glyoxaline " base "and " ion," the dicarboxylic acid being non-salt-forming, or to theaccumulation of acidic groups, since in the monocarboxylic acidp-nitration, although less than in 2-phenylglyoxaline, is still pre-dominant, just as in the series benzyl chloride, benzylidene chloride,and benzotrichloride there Ps a progressive change from para- tometa-nitrati~n,~~ The case of 4 : 5-dibromo-2-phenylglyoxaline,however, lends no support to this view, since it gives 63% of p-nitro-compound and only 14% of an unidentified isomeride.Hydantoins.-The additions to the literature on this subjectduring the last three years have been largely concerned with thesynthesis of new species.Many of these products have been pre-pared with a view to testing their pharmacological action, but muchuseful information on the formation and reactions of these sub-stances has also been obtained. An interesting example is thatafforded by the synthesis of glutathione 28 in w h i ~ h di(hydantoin-propiony1)cystine is an important intermediate.H. Biltz and K,Slotta 29 have described a method for the synthesis of hydantoins,depending upon the conversion, by the action of potassium cyanate,of aminoacetonitriles so into hydantoic acid nitriles (I), followed bysimultaneous hydrolysis and ring closure with hydrochloric acid tothe hvdantoin (11).Although the supposed stereoisomeride of ethyl 4-p-anisylidene-hydantoin-3-a-propionate turns out to be actually ethyl 4.paniayl-idenehydantoin-1-acetate, the same investigators have been able to3' A. F. Holleman, Re. traw. chim., 1914, 33, 1; A . , 1914, i, 513.9' J . pr. Chem., 1926, [ii], 118, 233; A., 1045.1 9 N. D. Zelinsky and a. Stctdnikov, Ber., 1908, 41,2061 ; A . , 1908, i, 607.Compsre Ann. Reporla. 1926, 22, 104ORQANIC CHElKISTRY.-PART m.177demonstrate the existence of two forms of the 1 : 3-disubstitutionproducts of both benzylidene- and anisylidene-hydantoins. Theabsence of stereoisomerism in the former is assumed to be due totautomerism, by which the double linking responsible for stereo-isomerism may become saturated.NH*CON=&CH,R NH*Co + co< co<SH*(!XCHRThe isomeride of lower melting point is invariably transformedinto that of higher melting point by boiling alcoholic hydrogenchloride, but the reverse change has been effected only in one case,viz., 1 : 3-dimethy1-4-ar~isylidenehydantoin,3~ and then only in smallamount by the action of alkali : both forms yield the same 1 : 3-di-methylanisylhydantoin on reduction.31 The lsvo-forms of 2-thio-5-methyl- and l-benzoyl-2-thio-5-methyl-hydantoins have beenprepared 32 by T.B. Johnson's method 33 from Lalanine and benzoyl-Lalanine. Alkali causes racemisation in both cases, due to enoh-ation. In the case of the benzoyl derivative, two equivalents ofalkali are necessary, as the first merely produces a salt withoutdisturbance of the centre of asymmetry.CHMe*NBz>cS ~ yHMe-NBz>C.aK --3 RMe-NBz>C.SK 60-NH GO- " C(0K)-NPyrazoZes.-H. J. Backer and W. Meijer34 find that in the pre-paration of pyrazolones by the action of hydrazine on ketonic estersthe first product is a 5-hydroxy-5-alkyloxydihydropyrazole (I),which may then lose either alcohol, producing the pyrazolone, orwater, forming an alkyloxypyrazole. The latter have long beenknown as by-products of the reaction 35 and the yield can be increasedto from 20 to 30:& by using a concentrated solution of hydrazinehydrochloride in methyl or ethyl alcohol.The 5-alkyloxypyrazoles described are readily nitrated in position4, except when the latter is occupied as in the 5-alkyloxy-4-alkyl-pyrazoles.Although Rosenmund's method for the preparation of aldehydes81 D.A. Hahn and E. Gilman, J. Amer. Chem. SOC., 1925, 47, 2941, 2953;A., 1926, 180, 181; compare E. P. Carr and M. A. Dobbrow, ibid., p. 2961;A., 180.31 B. Sjollema and L. Seeklee, Reo. trav. chim., 1926, 45, 232; 4., 414.9n J . BioZ. Chem., 1912,11, 97; A., 1912, i, 390; Amer. Chem. J., 1913, 49,69,197; A., 1913, i, 203, 399; J. Arne*. Chem. Soc., 1913, 35, 1130; A., 1913,i, 1104.84 Rcc.hau. chim., 1926, 45, 82, 428; A., 305, 741.*s L. Wolff, Ber., 1904, 37, 2827; A., 1904, i, 722178 A ~ U A L REPORTS ON TEE PROGRESS OF CHEMISTRY.by reduction of acid chlorides cannot be applied to %methyl-,4-bromo-3-methyl-, or 4-methyl-pyrazole-5-carboxylio acid or t o3 : 5-dimethyl- or 3-phenyl-5-methyl-pyrrtzole-4-carboxylic acid, asall these undergo dehydration on treatment with thionyl chloride,it can be used for the 1-methyl derivatives of these acids and theanalogous derivatives of pyrazole-3-carboxylic acid, but the yieldsare sma11.36Several long papers on isomeric relationships in the pyrazoleseries have appeared, but these are concerned mainly with experi-mental details and there is nothing of importance to add to thesummary given last year, beyond the new points that (a) alkylationof ethyl 5-methylpyrazole-3-carboxylate, followed by elimination ofthe carboxyl group, leads to the production of both 1 : 3- and 1 : 5-dialkylpyrazoles, ( b ) alkylation of pyrazolecarboxylic acids invariablygives rise to two isomeric acids, where two are theoretically possible,and (c) direct alkylation of 3(5)-methylpyrazole produces both 1 : 3-and 1 : 5-dialkyl derivatives.37I&a.zoles.-The preparation of a considerable number of newindazole derivatives has been described, among which may bementioned a series of indazyl-fatty acids.The latter were obtainedby the action of the ethyl ester of the appropriate bromo-acid onindazole, the acid residue entering the latter in position 2 a t tem-peratures ranging from 100" t o 120" and also in position 1 in varyingamounts a t higher temperatures.In presence of alkali alkyloxideboth isomerides are invariably formed. The two indazylaceticacids furnish the corresponding 1- and 2-methylindazoles by decarb-oxylation, when distilled under reduced pressure, but indazyl-P-propionic acid on similar treatment gives indazole and acrylic acid.I n the case of ethyl cc-bromoisobutyrate, the product of the primaryreaction is 2-ethylindazole, due, it is thought, to hydrolysis of theester by the hydrobromic acid formed in the initial stages followedby alkylation of the indazole by the ethyl bromideL. F. Fieser 39 has submitted 6-nitroindazole t o a number ofreactions vith a view to comparing the behaviour of heterocyclicsystems with benzene, without detecting any marked differences.Further, comparison of the reduction potential of sodium 6 : 7-indazolequinone-4-sulphonate with that of potassium p-naphtha-quinone-4-sulphonate, in buffer solutions over a wide range of p,,36 C. A.Rojahn and H. E. Kiihling, Arch. Phnrn,., 1926, 264, 337; A,,846 ; compare Ann. Reports, 1924, 21, 149.57 K. voh Auwers with H. Hollmann, Ber., 1926, 59, G01, 1282; with H.Nauss, &id., p. 611; with H. Stuhlmsnn, {bid., p. 1043; A,, 623, 624, 741,847; compare C. A. Rojahnand H. E. Kuhling, Ber., 1926,59, 607; A., 624.3 8 X. von Auwers and H. a. Allardt, Ber., 1926, 59, 95; A,, 307.3 0 J . Amer. Chem. soc., 1926, 48, 1097; A., 625ORGANIU UEEMISTBY .-PART III.179gave average values 0.620 and 0,630 volt, indicating a close relation-ship between the benzene and pyrazole rings.If, as already suggested,@ the supposed 1-acetylindazole is reallythe seven-membered ring substance 4 : 5-bemo-7-methylhept-1 : 2 : 6-oxdiazine (I), then the similarly produced '( 1-acetyl-3methylindazole " (11) (4 : 5-benzo-3 : 7-dimethylhept-1 : 2 : 6-oxdi-azine) should not be readily oxidised.41 This is found to be the caseas regards perbenzoic acid ; with potassium permanganate, how-ever, it yields o-acetamidoacetophenone, and the formation of thisis not readily explained on anything but the oxdiazine formule.It was not found possible to prepare (' 1-benzoylindazole " fromo-chlorobenzaldehydebenzoylhydrazine by ring closure withsulphuric acid, but the halogen atom of the 2-chloro-5-nitro-deriv-ative proved more mobile and by the use of potassium carbonate,copper powder, and potassium iodide in boiling cumene, 4-nitro-l-benzoylindazole was produced, identical with that of K.von Auwersand K. Schwegler.a2 The supposed 1-acetylindazole being disposedof, K. von Auwers and H. G. Allardt * have continued their investig-ation of the other two and, by a study of the addition of acetyliodide to (a) 2-methylindazole and ( b ) 1-methylindazole, have cometo the conclusion that the primary additive products are representedby formulae (111) and (IV) respectively, since the former is decom-(111.)posed by water into 2-methylindazole and the stable acetylindazole,m. p.41", which is now regarded as 1-acetylindazole (formerly calledstable 2-acetylindazole) ; it regenerates (111) when treated withmethyl iodide. The second additive product (IV) on treatmentwith water forms 1-methylindazole and acetic acid, the non-appearance of the expected 2-acetylindazole, rn. p. 106" (formerlycalled labile 2-acetylindazole), being due to the instability of thelatter. This isomeride does not react with methyl iodide a t atmo-spheric temperature and decomposes when heated, so that it hasnot been possible to form the additive product (IV) by the inversemethod.This discussion is extended by K. von Auwers and E. Frese 44 to40 See Ann. Reports, 1924, 21, 160.4l J. Meisenheimer and 0.Senn, Ber., 1926, 59, 199; A., 414.4t Ibid., 1920,63,1211; A., 1920, i, 640.48 Ibid., 1926,59,90; A., 306; compare Ann. Reports, 1924,21, 150; 1925,44 Ber., 1926, 59, 539; A., 629.22, 162180 ANNUAT, REPORTS ON THE PROQRESS OF OHEXISTRY.the monoacetyl derivatives of 7-amino-6-methylindazole, of whichtwo forms have been obtained, represented by formula (V) and (VI),/\I I 7 NA M7 I I 7 */ -. ''m (v**.'(V.) M7 \ :I \ i.. w.1 \\/\/AcHN N AcIN NHN=CMederived, respectively, from the labile 7-acetamido-2-acetyl-5-methyl-indazole and the stable 7-acetamido-1-acetyl-5-methylindazole. Ofthe latter two, the first is formed from the parent base by the actionof acetic anhydride a t 100" and is converted into the second bydistillation under reduced pressure.Analogous di- and mono-benzoyl derivatives were also obtained. Rolonged ebullition of7-amino-5-methylindazole with acetic anhydride gives rise to a tri-acetyl derivative instead of the expected anhydro-base (VII), and,similarly, anhydro-bases could not be obtained from either themono- or the di-acetyl derivative by the use of various dehydratingagents. Further, it was not found possible to prepare an anhydro-base from 7(4)-amino-2-methylbenziminazole by the use of eitheracetic acid or anhydride and this method of converting o-diaminesinto anhydro-bases appears not to be capable of general application.Diazines.Pyrazine Derivatives.-According to J. von Braun, 0. Goll, andF. Z0be1,~~ the piperazine ring (hexahydropyrazine) is a veryunstable structure, the replacement of the 4-methylene group of thepiperidine by the imino-group causing much greater weakness thanits replacement by oxygen as in morpholine.Thus the action ofammonia on piperazinedipiperidium bromide leads to fissionexclusively in the piperazine ring. With cyanogen bromide,dimethylpiperazine furnishes methylvinylcyanamide and methyl-@-bromoethylcyanamide. Similarly, when piperazinebisdihydro-isoindolinium bromide (I) is treated successively with silver oxideand boiling water, it is the piperazine ring which is opened, leavinga@-bisdihydroisoindylethane (11). The corresponding piperazid-ditetrahydroisoquinolinium bromide under like conditions yieldsa~-di-2-tetrahydroisoquinolylethane and 2-@-hydroxyethyltetra-I s Ber., 1926, 59, 936; A., 739OROANIC CHEMISTRY.-PART III.181hydrokoquinoline along with some acetaldehyde and tetrahydroiso-quinoline.On treatment with methyl iodide, piperazine yields first 1 : 4-di-methyl- and then 1 : 1 : 4 : 4-tetramethyl-piperazine. Similarly,2 : 5-dimethylpiperazine yields first the 1 : 2 : 4 : 5-tetramethylderivative and finally 1 : 1 : 2 : 4 : 4 : 5-he~amethylpiperazine.~~C. Stoehr 47 showed that 2 : 5-dimethylpyrazine on reduction withsodium in alcohol produces two stereoisomeric forms (a and p) of2 : 5-dimethylpiperazine. The p-form, like the a-form, has now beenresolved into its enantiomorphs and the two are shown to be respec-tively trans- and cis-forms. They are produced in the proportion19 : 1 in the initial reduction.48 Enolic forms of various 2 : 5-di-ketopiperazines have been obtained and have been the subject ofinteresting biological ~peculations.4~Pyrimidines.-Previous investigation having shown that gly-oxalines (cyclic amidines) and open-chain amidines yield on methyl-ation mixtures of isomeric N-methyl derivatives,M the work hasbeen extended 5 1 to the partly cyclic amidine, 4-anilino-2-phenyl-6-methylpyrimidine (I).This yielded a methiodide, m.p. 220°, in which the second methylgroup must be either at N 1 or 3 in the pyrimidine ring, since ontreatment with alkali it yields, not the colourless base representedby (II), but a yellow, unstable base which must be either 4-phenyl-imino-2-phenyl-3 : 6-dimethyl-3 : 4-dihydropyrimidine (111) or the1 : 6-dimethyl isomeride of this (IV).This on further methylation furnishes a product which is identicalwith that obtained on methylation of (11) and must be 4-methyl-anilino-2-phenyl-3 : 6(0r 1 : 6)-dimethylpyrimidinium iodide (V =46 E. Abderhalden and R. Haas, 2. physiot. Chem., 1925, 148, 245; 149,94; A., 1926, 79, 181.L7 J . pr. Chem., 1893, [ii], 47,439; 1897, [ii], 55, 49; A., 1893, i, 486; 1897,i, 298. '* F. B. Kipping and W. J. Pope, J., 1926, 1076; A., 739; compare W. J .Pope and J. Read, J., 1912, 101, 2325; 1914, 105, 219.40 E. Abderhalden and co-workers, 2. phy8iOl. Chem., 1925, 148, 100, 298 ;1926, 152, 88; 153, 83; 155, 195, 200; 157, 140; A., 181, 305, 630, 740,959, 960.m F. L. Pyman, J., 1923.123, 367, 3359 and Ann. Reports, 1924, 21, 147;1925, 22, 156.j1 R. Forsyth and F. L. Pyman, J., 1926, 2502; A., 1156182 ANNUAL REPORTS ON THE PROGRESS OB CHEMISTRY.3 : 6 form). In the original methylation, the second iodide, m. p.182-183”, formed proved t o be a molecular mixture of (V) with theoriginal base (I). Substance (V) on distillation yields the methyl-anilino-base (II).These results are in harmony with those obtained by the applic-ation of methyl salts t o those partly cyclic amidines which containone of their nitrogen atoms as a member of an aromatic nucleus,such as the suitably substituted thiazoles,62 2-aminopyridine 63 and1-aminobenzthiazole.” The reason for this preferential methylationof the ring nitrogen atom is probably not the weaker basicity of thisnitrogen atom but the general structure of the molecule, partlycyclic amidines of the type now discussed tending to react in theform in which the cyclic nitrogen is doubly linked, that is, as amino-derivatives of aromatic compounds rather than as the isomericiminodihydro-derivatives.Among a considerable number of interesting observations onuracil, thymine, cytosine, and other pyrimidine derivatives, referencemay be made to the isolation of 5-methylcytosine from the hydro-lytic products of the nucleic acid of Bacillus tuberculosis 55 and towork from the same laboratory on the reduction of cytosine (I) byhydrogen in presence of colloidal platinum. The products arehydrouracil (11) and ammonia. With 5-nitrouracil, &amino-NH-m $0 i H NH-C‘H, . NH-bH,(1.1 (11.) (111.) (IV.1uracil is fist formed and then partly hydrolysed first to 5-hydroxy-uracil (isobarbituric acid) and iinally to a new substance, to whichformula (111) or (IV) is assigned.56H. Biltz and T. Kohler 57 have produced what appears t o besatisfactory evidence that 5-benzoylbarbituric acid (V) is formedwhen barbituric acid is treated with benzoic anhydride and that theacyl group also takes up the same position in the 1 : 3-dialkyl-N= .NH, YH-70 F-YO FTO YO CH, g-ZE;OH YO COsf G. Young and S. I. Crookes, J., 1906, 89, 59.58 A. E. Tschitschibabin and R. A. Konowalowa, Ber., 1921, 54, 814; A . ,64 R. F. Hunter, J . , 1926, 1385; A., 849.6 6 T. B. Johnson and R. D. Coghill, J . Arne?. Chern. Soc., 1925, 47, 2838;5 6 E. B. Brown and T. B. Johnson, ibid., 1924, 46, 702 ; A . , 1924, i, 567.67 Ber., 1923, 66, 2482; A., 1924, i, 210.1921, i, 460.A., 1926, 79ORGAXIU CHEMISTRY .-l?ART Ill. 183barbituric acids. With hydroxylamine, it yields the o x h e of5-amino-5-benzoylbarbituric acid (VI), and it is converted by methylsulphate in presence of alkali into the methyl ether of the enolicform (VII). A similar study has been made of 5-nitrobarbituricacid. 58rH-7070 EBz $0 CHBz &OK?) *CPh :NOHNH-bO NH-C- OMe(V.1 WI.) (VII.)The ingenuity of inventors in kcling new variants of alkyl-barbituric acids for use as hypnotics shows little diminution and inthis connexion mention may be made of an attempt to correlatestructure with therapeutic action in this group.69 P. Fleury hasdescribed in a preliminary fashion a number of mercury derivativesof dialkyl- and other barbituric acids which may belong to thetype described by E. Rupp and I<. Miiller61 as produced by theinteraction of mercuric acetate and sodium diethylbarbiturate.Here a precipitate is &st formed of the acetoxymercuri-derivative(VIII.) Etzg 70 /Et,C 70I.(VIII), and the fltrate from this, on further treatment with theorganic component, gives the more complex mercury compound (IX).NH-QO NH-(ilor 7 0 - v -?-YOQO gEt2 (IX.1 1 FO-lfHO-N*Hg*OAc ~ o - N * H ~ 2-~- oPurine Croup.In this group, a considerable number of syntheses have beeneflected, especially by H. Biltz and his co-workers.62 Among thesemay be mentioned that of 5-amino-4-hydroxy-4 : 5-dihydrouricacid,s3 which is converted by nitrogen trioxide into the correspondinguric acid glycol. The atability of these two aubstances towardsvarious reagents has been studied in comparison with that of thecorresponding +-uric acid derivatives. H. Wieland and C. Schopf 64have isolated yellow (xanthopterin) and white (leucopterin) pigments6 a H. Biltz and K. Sedlatscheck, Ber., 1924, 67, 330; A., 1924, i, 429.m A. W. Dox, J . Amer. Pharm. Assoo., 1923, 12, 602; A , , 1924, i, 668;6o Bull. SOC. chim., 1925, [iv], 37, 1656; 1926, [iv], 39, 99; A., 305, 420.Ia Bcr., 1924, 57, 175; 1926, 68, 2190; A., 1924, i, 431; 1925, i, 14626s H. Biltz and W. Klernm, Annakm, 1926, 448, 134; A., 96?.J . Amer. Chem. Soc., 1924, 48, 2843; A., 1925, i, 301.Arch. Pharm., 1926, 264, 362; A., 852.Ber., 1925,68,2178; 1926, 59, 2067; A., 1925, i, 1464; A,, 1926,1168184 ANNUAL REPORTS ON THE PROURESS OF CHEMISTRY.from the wings of lemon and white butterflies and suggest thatthese may be represented by the following formulae, respect,ively :Much attention has been directed during the last three years toattempts to determine the mechanism of oxidation of uric acid andits derivatives. With a variety of agents tried in acid, neutral, orbuffer solutions by H. Biltz and H. S ~ h a u d e r , ~ ~ oxaluric acid (111)is the most constant product, and, although it can arise from suchpossible intermediates as uric acid glycol, alloxan, or allantoin, theexperimental evidence aupports, but does not clearly establish, theview that it comes from the hypothetical hydroxydicarbamidoethane-carboxylic acid (I), for which the names hydroxyacetylenediuine-carboxylic acid and hydroxyglycolurilcarboxylic acid also havebeen used.YH-C(CO,H)*NH NH2 Y"2 NH2 c* NH-C(OH)-NH NH-C-QO 70 ($02H), 70 $0 P HNH NH- 0(1.) (11.) (111.)This has already been postulated as the precursor of uroxanic acid(11), obtained when uric acid is oxidised in alkaline solutions,66 andit is now suggested that during oxidation in acid or neutral solutions,uroxanic acid is not formed because under these conditions carbondioxide is spontaneously lost from hydroxydicarbamidoethane-carboxylic acid (I). All attempts to isolate the latter have failed,but in suitably oxidised uric acid solutions its presence is regardedas proved since, by acidification with acetic acid followed byreduction with sodium amalgam, dicarbamidoethane (IV) (acetylene-diureine) is obtained. This substance is also produced Then allantoin(V) is reduced under similar conditions in presence of sulphuric acid.In this case, reduction is believed to precede ring formation, andthis is regarded as further evidence for the monocyclic structure (V)of a l l a n t ~ i n . ~ ~ A general discussion of the breakdown of uric acid8 6 J . pr. Chetn., 1923, [ii], 108, 10s; A., 1924, i, 569.6 4 R. Berend, Annalen, 1904, 338, 141; A., 1904, i, 950; compere H.Biltz and F. Max, Ber., 1920, 63, 1964; A . , 1920, i, 884.6 7 H. Biltz and G. Sohiemann, J . pr. Chem., 1926, [ii], 113, 77; A,, 741;compare H. Biltz and F. Max, Ber., 1921, 64, 2461; A., 1921, i, 893, and H.Biltz and H. Hmisoh, J. pr. Chem., 1926, [ii], 112, 138; A., 414ORQAEIC CHEMISTRY .-PART III. 186glycols and their degradation products has been published byK. H. Slotta.e8The smooth conversion of 4 : 5-dimethoxy-4 : 5-dihydrouric acid(uric acid glycol dimethyl ether) into allantoin (V) by potassiumhydroxide appears to be exceptional, since allantoins are either notformed or are produced in minute quantity by the action of alkalison other uric acid glycol ethers. Thus, in the glycol ethers con-taining a methyl group in position 3 in the pyrimidine ring, fissionoccurs between positions 1 and 6, methylamine, cyanic acid, andcarbon dioxide are lost, and a substituted hydantoin is formed,6Balthough disruption may be less complete than this, as with1 : 3 : 7-trimethyluric acid glycol dimethyl ether (VI) which, ontreatment with 30% potassium hydroxide solution, gives 4-8-di-methylcarbamido-6-methoxy-1 -methyl-A3-glyoxal-2-one (VII).NMe.CO.T( OMe).NMe NHMe FH(OMe)*NIVIe>CO kO*NMe*C( 0Me)-NH >CO + CO.me*C-----N(VI.) (VII.)T. A. HENRY.K. H. Slotts, J. p. Chem., 1925, [ii], 110, 264; A . , 1925, i, 1189.H. Biltz and H. Klein, Ber., 1925, 58, 2740; A,, 1926, 182. For a similarstudy of the action of alkalis on alkyluric acids, see E. S. Gatewood, J. Amw.Chem. Soc., 1923, 45, 3056; 1925, 47, 2175, 2181; A., 1924, i, 218; 1925,i, 1188, 1189. Compare L. Piaux, Bull. SOC. chirn., 1925, [iv], 37, 311; 1926,[iv], 59, 1471; A., 1925, i, 592; A,, 1926, 1261

ISSN:0365-6217    

DOI:10.1039/AR9262300074

出版商:RSC    

年代:1926

数据来源: RSC

摘要:

ANALYTICAL CHEMISTRY.THERE is little of entirely novel character to report in analyticalchemistry during the year under review. Several improvementsand advances in potentiometric and conductometric determinationshave been recorded. The difficulties attaching to many of theprocesses of estimating and detecting substances by the ordinarymethods are again discussed and examined in detail. Micro-chemical determinations are likewise being actively investigated,with a considerable measure of success. Some attention has beendirected to the separations of the rarer alkali metals and a usefulmodification of the bleaching method for the colorimetric deter-mination of fluorine has been described. We have, in this Report,given a rbume' of the more important methods for the estimationof large and of small quantities of fluorine (excluding the well-known silicon fluoride method), since the accurate determinationof this element is becoming of increasing importance in manydirections.Inorganic Analysis.for the rapidand ready detection of certain metals by use of drops of the solutionsto be tested have now been extended to embrace all the commoncations; the scheme avoids the use of hydrogen sulphide.Theprecipitates produced in solutions of the heavy metals by 36 aliphaticand heterocyclic bases have been studied with a view to the possibleapplication of the results to the separation of various metals. Inparticular, the violet-blue precipitate yielded by glyoxaline withcobalt constitutes a delicate test for this metal.Diphenylthio-carbazone forms highly-coloured compounds with a number ofheavy metals most of which are soluble in chloroform and carbondisulphide. Sensitive and characteristic tests for zinc and copperare based on this rea~tion.~Traces of silver in ores can be detected by microchemical reactionsdue t o the formation of rubidium silver gold ~hloride.~ The form-1 N. A. Tananaev, Z. anorg. Chem., 1924, 133, 372; 140, 320; A . , 1924,2 Ulcraine Chem. J., 1926, 2, 27; A., 927.8 E. J. Fischer, W k . Ver6ff. Siemens-Konz., 1925, 4, 171; A., 1926, 492.6 W. Geilmann, 2. anwg. Chem., 1926, 155, 192; A., 1019.Qualitative.-The methods previously describedii, 671; 1925, ii, 324.Ibid., p. 158; A., 1926, 491.18ANALYTICAL CHEMISTRY.187ation of a copious white precipitate on addition of 1% brucinesulphate and potassium bromide t o a cadmium solution serves t odetect this metal in the presence of copper,6 and the reaction maybe utilised to differentiate between bromides and chlorides. Micro-scopic examination of the deposit on a copper wire acting as cathodeis capable of revealing mercury when present to the extent of O ~ Y0.5 mg. per litre.'Aluminium gives with an extract of dried alkanet root a charac-teristic purple lake when ammonia is added in excess.8Nickel sulphate gives with a large excess of concentrated hydriodicacid an intense red colour similar t o that of ferric thiocyanate;this colour disappears on sufficient dilution by water. Charac-teristic effects on the colour and absorption spectra of solutions ofcobalt salts are induced by hydrobromic and hydriodic acidsSBSolutions of cobaltous salts give with potassium ferrocyanide in thepresence of ammonia a red coloration, perceptible in very dilutesolutions, and the test is not vitiated by a considerable excess ofnickel salts.1° The sensitiveness of the borax bead test for cobaltcan be greatly increased by microscopical examination of minuteborax beads.11The sensitivity of a number of reagents for the strontium ion hasbeen worked out ; calcium can be detected, after removal of bariumand strontium as chromates by prescribed methods, by means ofpotassium ferrocyanide.12 Sodium ferrocyanide in the presence ofcalcium chloride gives a precipitate with aqueous solutions con-taining rubidium and cssium ; potassium and ammonium are onlyprecipitated from 50% ethyl-alcoholic solution, whilst sodium andlithium are not affected. These reactions afford a means of soparat-ing the alkalis.13 Thallium even in dilute solution also forms aprecipitate when calcium acetate is used with sodium ferrocyanide.14Complete qualitative separations of the various metals of thealkali group are described in a lengthy paper.15 Optimum con-e R.Meurice, Ann. Chim. anal., 1926, [ii], 8, 130; A., 703. ' H. S. Booth and N. E. Schreiber, J . Amer. (?hem. SOC., 1925, 47, 2625;* H. W. Estill and R. L. Nugent, ibid., 1926, 48, 168; A., 263.lo L. Minddev, Mitt. wiss.-tech. Arb. Republ. [Ems.], 1924, 13, 57; A.,A,, 1923, 40.G.Denig6s. Compt. Tend., 1926, 183, 55; A., 930.1926, 264.l1 J. M h , KoZZ.-Che+n. Beih., 1926, 23, 309; A., 1116.l* D. Raquet, Ann. Chim. anal., 1926, [ii], 8, 3; A., 262.Is T. Gaspar y Arnal, Anal. 2%. Q u h , 1926, 24, 99; A., 691; F. Diaz deRada and T. Gaspar y Arnal, &bid., p. 160; A., 702.T. Gaspar y Arnal, ibid., p. 153; A,, 703.S. At0 and I. Wada, Sci. Papers Imt. Phys. Chem. Rw., 1926, 4, 263;A., 929188 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.ditions under which the oxalate test for sodium should be carriedout are described; borax is the only common sodium compoundwhich does not respond to this test. Potassium pyroantimonateis a better reagent and may be used in presence of boric acid.ls Theprecipitation of sodium magnesium uranyl acetate in the presenceof alcohol is of value in the detection of small quantities of sodiumin the presence of potassium and magnesium, but is valueless forquantatitive work.1'For the microchemical detection of germanium, no characteristicreagent was discovered; the most practicable test was found todepend on the conversion into sodium fluogermanate or rubidiumgermanomolybdate following a preliminary separation from severalelements which normally give positive tests with fluorides andmolybdates.ls In the absence of iron and metals of the fist twoanalytical groups, the coloration given with pyrocatechol indicatesthe presence of cerium even in minute traces.19The hydrogen peroxide test for titanium is not suitable for spotanalysis on filter-paper ; for this purpose, the red coloration givenby chromotropic acid is most satisfactory.Copper, iron, andtitanium interfere with the ferrocyanide spot-test for uranium,but this difficulty may be obviated by reducing the former withpotassium iodide and decolorising the iodine with thiosulphateaaOThe lakes formed by " aluminon " (aurintricarboxylic acid) with anumber of the rarer metals have been more completely investigated ;with the exception of the beryllium lake, all are dissolved ordecolorised by ammonium carbonate.21 Reactions of a number ofhydroxyanthraquinone derivatives with zirconium and hafniumare described ; the reddish-violet solution obtained in the case ofalizarinsulphonic acid is a sensitive reagent for fluorides, which,by converting the zirconium into a complex fluoride, cause thesolution to become yellow.22 As the result of a study of the reac-tions between vanadic acid, hydrogen peroxide, and sulphuric acid,the best concentration of sulphuric acid for the detection of vanadiumby this test has been workedTraces of soluble ruthenium salts may be detected by heatingthe solution, rendered alkaline with sodium hydroxide, in a current16 N.Schoorl, Pharm. Weekblad, 1926, 63, 555; A., 814.1 ) E. Crepaz, Ann. Chim. Appl., 1926, 16, 219; A., 1019.15 E. M. Chamot and H. I. Cole, Mibochem., 1926, 4, 97; A., 1019.19 L. Fernandes, Cfazzetta, 1925, 56, 616; A,, 1926, 140.20 N. A. Tananaev and 0. A. Pantschenko, 2. anorg. Chem., 1926, 160,21 A.R. Middleton, J . Amr. Chem. Soc., 1926, 48, 2125; A., 930.22 J. H. de Boer, Rec. traw. chim., 1926, 44, 1071; A., 1926, 40.15 J. Meyer and A. Pawlettct, 2. anal. Chern., 1926, 89, 15; A,, 1020.163; A., 377. See also Ukraine Chem. J., 1926, 2, 43ANALYTICAL CHEMISTRY. 189of chlorine; a brown coloration in an absorbent consisting ofaqueous alcohol containing hydrochloric acid indicates ruthenium.24Reactions of the platinum metals with a number of typical organicand inorganic compounds have been tabulatedlZ5 and a schemefor the qualitative separation of these metals has been worked out.26Specific and delicate tests for nitrate and for hydroxylamine basedupon conversion into nitrite and application of the diazo-reactionhave been described, together with appropriate methods for thepreliminary removal of nitrites.27 A test for iodate, available inthe presence of bromate, chlorate, and nitrate, depends upon theliberation of iodine by reaction with thiocyanic acid.2* The effectsproduced by salts of cobalt, copper, and mercury serve to distinguishbetween carbonates and bicarboyates, sulphites and bisulphites.2QBromine, liberated by suitable methods from bromides, hypobromites,or bromates, may be detected in very small amounts by the cparac-teristic crystalline precipitate it produces in a solution of m-phenyl-enediamine in 5% sulphuric acid.3OQuantitative.-Pyridinium perchlorate may readily be obtainedfrom technical pyridine in a pure state free from homologues, andcan be used as an acidimetric ~tandard.~l Borax or potassiumiodate, used under appropriate conditions, is preferred to sodiumcarbonate for the standardisation of hydrochloric acid.32 Constant-boiling hydrochloric acid remains unaltered in strength for longperiods and is therefore available for dilution for standard solutions.33Two studies have been made of the variability of standard sodiumthiosulphate solutions.34 The high results obtained in the titrationwith thiosulphate of the iodine set free by potassium dichromate inacid solution are stated to be due to liberation of iodine by atmo-spheric oxygen in the presence of chromic salts ; normal values areobtained if the reaction solutions are first boiled and the processcarried out in an atmosphere of carbon dioxide.35Methods depending upon the formation of cyanogen halide have94 H. Remy, 2.angew. Chew, 1926, 39, 1061; A,, 1219.p 6 S. C. Ogburn, jun., J . Amer. Chern. SOC., 1926, 48, 2493; A,, 1117.26 Idem, ibid., p. 2607; A., 1117.2 7 J. Blom, Ber., 1926, 69, [B], 121; A., 375.*a J. Bicskei, 2. amrg. Chem., 1926, 151, 127; A., 375.29 T. Gasper y Amal, Anal. p68. Qukm., 1926, 24, 267; A., 928.80 C. W. Mason and E. M. Chamot, Mikrochem., 1926,4, 145; A., 1220.$1 F. Arndt and P. Nechtwey, Ber., 1926, 59, [B], 448; A,, 626.Is I. M. Kolthoff, J . A m . Chem. SOC.. 1926, 48, 1447; A., 813; Pharm.98 J. A. Shaw, I d . Eng. Chem., 1926, 18, 1066; A., 1220.8' C. M a p , 2. awl. Chem., 1926, 68, 274; A., 814; E. Schulek, ibid.,v6 K. Bottger and W.Bottger, ibid., 1926, 69, 146; A,, 1221.WeekblacE, 1926, 03, 37; A,, 1926, 139.p. 387; A., 1017190 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.been studied comprehensively and applied to the determinationof chloride, bromide, and iodide, alone or in Thetitrations of thiocyanic acid, of arsenious acid, and of antimonywith potassium bromate have been investigated from the point ofview of the optimum acidity ; the potentiometric method permitsof a wider range and therefore is preferred to the use of methyl-orange?'Extract of blue cabbage, used as an indicator, gives a series ofcolour changes between pH 2 and pH 11, ranging from red throughblue ( p , 6.8-7.1) and green ( p , 8) to yellow; it is, however, ex-tremely sensitive to carbon dioxide.38 An aqueous solution ofyatrenum (which consists of an iodohydroxyquinolinesulphonic acidwith an equivalent of sodium bicarbonate) is strongly colouredbetween p K 1 and p , 8, with maximum intensity a t pH 4 ; the possi-bility of its use, with buffer solutions, as an indicator is discussed.39Under special lighting conditions, quinine 40 and umbelliferone 4 1may be used as fluorescent indicators. The first is suitable forturbid liquids and both are available for coloured solutions.Vanadous sulphate is an even more powerful reducing agent thantitanous sulphate ; whilst the latter maintains its titre in 4iV-sulph-uric acid in a burette exposed to air for 12 hours, vanadous sulphatemust be used within 1 Uranous sulphate is a mild reducingagent the solution of which is stable in air.Its preparation anduse for the determination of ferric salts are described inDiphenylamine as an internal indicator has been applied in con-junction with reduction by liquid amalgams to the determinationof phosphoric acid, ferricyanide, chromic acid, and ferric salts.44" Citarin," the sodium salt of anhydromethylenecitric acid, canbe used for the quantitative precipitation of silver and of gold,owing to the liberation of formaldehyde from the hot alkalines0lution.~5 Small amounts of silver can be separated as metalfrom large quantities of lead or copper by boiling the alkalinesolution in the presence of glycerol.*656 R. Berg, 2. anal. Chem., 1926, 69, 1; A., 1017.5 7 T. Nakazono and 8. Inoko, J .Chem. SOC. Japan, 1926, 47, 20; A,, 1115.38 T. Milobedzki and S. Jajte, Rocz. Chem., 1926, 6, 177; A,, 927.39 IF. W. van Urk, Phamn. VeekbM, 1926, 63, 685; A,, 813.4 1 R. Robl, Ber., 1926, 59, [B], 1725; A., 1115.43 C. Vortmann and F. Binder, 2. anal. Chem., 1925, 67, 269; A., 1926,263.K. Someya, 2. anorg. Chem., 1926, 152, 368, 382, 386; A., 702, 706;see dso 8ci. Rep. TGhoku Imp. U n k , 1926,15,399, 417, 426; A., 1116, 1117.L. Vanino and 0. Guyot, Arch. Pharm., 1926, 264, 98; A,, 491.R . Mellet and A. Bischoff, Compt. rend., 1926, 182, 1616; A., 813.A. S. Russell, J., 1926, 497; A., 692.46 E. Donath, Chm.-Ztg., 1926, 60, 222; A., 491ANALYTICAL CHEMISTRY. 191Lead may be separated from silver as phosphate from slightlyammoniacal tartrate solution, the temperature of precipitationbeing less than 80' to avoid reduction of the silver ; silver may beseparated by addition of potassium iodide to the boiling ~olution!~The effect of varying concentrations of hydrochloric acid on theprecipitation of cadmium , bismuth, and lead by hydrogen sulphidehas been investigated once more and the requisite conditions fordirect separation of metals of this group are described!8Suggestions are given to prevent oxidation of cuprous iodide inWinkler's gravimetric method for the determination of copper ascuprous iodidenPg Benzoin monoxime does not separate coppercompletely from iron, aluminium, or zinc, its use in this connexionbeing critici~ed.5~ The micro-determination of copper by electro-lysis and iodometric titration is applied to 0.5 mg.and less.s1Bismuth solutions hydrolyse in the presence of bromide andbromate to basic bismuth bromide. This reaction, which is moredelicate than that due to hydrogen sulphide, has been applied tothe separation of bismuth from zinc, copper,'cadmium, and lead.6aThe methods for the complete removal of mercury from solutionby deposition on copper and subsequent determination by sublim-ation have been reinvestigated and placed on a satisfactory basissuitable for large or small q u a n t i t i e ~ . ~ ~ A number of papers dealwith the determination of very small quantities of mercury theseparation of which is effected by electrolysis on gold and weighingthe metallic mercury ; conversion into red mercuric iodide serves asa confirmatory testss4In the absence of gold, mercury, selenium, and tellurium, arsenicmay be precipitated by stannous chloride and determined as theelement, in which form it may be weighed; the results tend to behigh.65 With certain modifications, arsenic may be reduced to*' G.Vortmann and 0. Hecht, 2. anat. Chem., 1925, 67, 276; A., 1926,262; G. Vortmann, Analyst, 1926, 51, 456; A., 1019.W. Manchot, G. Grassl, and A. Schreeberger, 2. anal. Chem., 1926, 67,177; A., 1926, 40; see also S. Krishnamurti, J., 1926, 1549; A., 814.I. M. Kolthoff and H. A. Kuylman, Chem. WeekbEacE, 1926, 23, 185;A., 592.so E . Azzalin, Ann. Chim. AppZ., 1925, 16, 373; A., 1926, 140.I1 IT. Schoorl and H. Begem-, Rec. trau. chim., 1925, 44, 1077; A., 1926,64 L.Moser and W. Maxymowicz, 2. anal. Chem., 1925, 67, 248; A., 1926,6* B. S. Evana and S. G. Clarke, Analyst, 1926, 51, 224; A,, 704.64 A. Stock and R. Heller, 2. angew. Chem., 1926,89,466; A,, 703; A. Stockand E. Pohland, ibid., p. 791 ; A., 814; H. S. Booth, (Miss) N. E. Schreiber,and K. G . Zwick, J. Am?. C h m . rSoc., 1926, 48, 1815; A., 929.40; H. B. Dunnicliff and K. Ram, Kolloid-Z., 1926, 38, 168; A., 376.264.R. Fnidli, Pharm. Zentr., 1926, 67, 241; A., 591192 ANNUAL RBPORTS ON THE PROGRESS OB CHEMISTRY.element and determined in the presence of selenium.66 I n theGutzeit test, a freshly-prepared mercuric bromide paper is highlysensitive and preferable to mercuric chloride; 57 the use of glasswool in place of filter-paper and cotton wool in the purifying tubeof the Guteeit or Marsh apparatus considerably lengthens theeffective life of the tube.58 Arsenic acid may be determined byreduction with titanous chloride and back titration with ferricalum.59Iron may be titrated with titanous chloride in the presence ofcopper by the use of the chromic acid compound of s-diphenyl-carbohydrazide, which is reduced instantly by cuprous chlorideand very slowly by titanous chloride.60 Iron is quantitativelyprecipitated under certain conditions from 2N-acid solution con-taining 2% ammonium salt by the addition of an alkali salt ofbis-p-chlorophenylphosphoric acid ; the precipitate is Gnally con-verted into hydroxide by treatment with ammonia.61Aluminium can be satisfactorily separated from magnesium,even in the absence of added ammonium salts, by adding ammoniauntil p , 7 is reached (blue with bromothymol-blue), but magnesiumis carried down if pa exceeds 7.62 Chromium salts are completelyoxidised to chromic acid by boiling in alkaline solution with leaddioxide, the excess of which is readily removed by Htration.68 Adirect permanganate titration method similar to the Volhardmethod for chromium 6* and manganese 65 salts, depending uponthe use of excess of sodium acetate, has been worked out and isshown to be available in the presence of much iron. The varyingfactors influencing the oxidation of manganese salts to permanganicacid and the conditions for securing complete oxidation have beenstudied,66 and it is shown that sulphuric acid may advantageouslybe substituted for nitric acid in the determination of manganeseby the bismuthate method.676 6 R.Fridli, Pharm. Zentr., 1926, 87, 369; A., 702.G. Kemmerer and H. H. Schrenk, Ind. Eng. Chem., 1926, 18, 707; A,,928.66 T. J. Ward, Amlyst, 1926, 51, 457; A., 1018.59 A. W. Francis, J . Amer. Chem. SOC., 1926, 48, 665; A,, 490.O D L. Brandt, Stahl u. Eisen, 1926, 46, 976; B., 762.F. Zetzache and M. Na.chmam, Helv. Chim. Acta, 1926, 9, 420; A., 705.A. Lasieur, Ann. Chim. anal., 1926, [ii], 8, 97; Compt. rend., 1926, 182,E. Muller and W. Messe, 2. anal. Chem., 1926, 89, 165; A., 1222.B. Reinitzer and P. Conreth, ibid., 1926, 88, 81; A., 492.as Idem, ibid., p. 129; A., 705.A. Travera, Compt. rend., 1926, 182, 1088; Ann.Chim., 1926, [XI, 8, 56;B. Perk, I d . Eng. Chm., 1926, 18, 697; A., 704.384; A., 376.A., 704ANALYTICAL CHEMISTRY. 193The oxalate separation of calcium and magnesium continues toattract attention, and the effective separation is shown to be dueto the degree of supersaturation of magnesium oxalate; 68 it isimportant to note that calcium oxalate is rapidly and quantitativelyconverted into carbonate by heating in it current of dry carbondioxide a t 675-800°.6gThe cobaltinitrite method for the determination of potassiumis shown to be available in the presence of sulphate and is thusbetter than the perchlorate in this case ; further confirnation thatthe composition of the precipitate after drying at 100" isK2NaCo(N0,),,H,0 has been obtained.70 It has been foundadvantageous to replace the acetic acid by tartaric acid in preparingthe reagent.71 Determination of the cobalt in the precipitatedcobaltinitrite has been applied to the micro-determination of smallquantities of potas~iurn,~~ whilst for micro-determination of sodiumuse is made of the triple nitrite 6NaN02,9CsN0,,5Bi(N0,), throughelectrolytic separation of bismuth.73Rubidium may be precipitated quantitatively as silicotungstate,RbsSiWlzOez, by addition of sjlicotungstic acid, but in the presenceof more than 1% of potassium the precipitate requires furthertreatment with I)% salt solution to remove co-precipitated potass.ium.74 Both rubidium and cssium may be precipitated from thealcoholic solution of their chlorides and weighed as chlorostannates.If the two metals are present together, the cssium is subsequentlyseparated as a triple chloride with antimony and iron and thenconverted into and determined as perchlorate.The precipitateformed by the addition of sodium cobaltinitrite to a solution of arubidium salt contains varying proportions of sodium, but thecssium salt, precipitated a t 80°, is definitely CS,CO(NO,)~,H,O. 75Thallium also is quantitatively precipitated a t 80" by sodiumcobaltinitrite, the product dried a t 100-110" having the compositionTl;NaCo(NO,),. In other methods for determination of thallium,the metal is either weighed as element or estimated volumetrically,the thallium being precipitated by a measured excess of potassium6E W.M. Fischer, 2. anorg. Chem., 1926, 153, 6 2 ; A,, 703.H. W. Foote and W. M. Bradley, J. Amer. Cheni. Soc., 1926, 48, 676;A,, 491.'O M. A. Hamid, Artalyst, 1926, 51, 450; A,, 1019; L. le Boucher, Anal.Pls. Qlsim., 1925, 23, 540; A., 1926, 491.'l M. Wikul, 2. anorg. Chem., 1926, 151, 338; A., 491.M. Delaville and P. Cmlier, Compt. rend., 1926, 182, 701; A,, 491.78 E. Tschopp, Helv. Chim. Actct, 1925, 8, 893; A,, 1926, 39.7 4 P. Freundler and (Mlle.) Y. MBnager, Compt. rend., 1926,182, 1158; A,,76 W. Strecker md F. 0. Diaz, 2. anal. Chem., 1925,87, 321; A., 1926, 261.702.REP.-VOL. XXIII. 194iodide.'% Thallous salts are quantitatively oxidised by potassiumiodate in the presence of a large excess of hydrochloric acid and sodetermined,77 or by potassium bromate.Thallic salts may alsobe titrated potentiometrically with titanous chloride in the presenceof ammonium acetate.78The requisite but simple precautions for the accurate determin-ation of uranium gravimetrically as U,08 following precipitationas (NH4)2U207 or volumetrically by means of permanganate arediscussed. T9 Sodium cacodylate separates uranium from othermetals of the iron group. The precipitate is [(CH,),AsO],UO, andmay be weighed in this form.80 Zirconium may be quantitativelyseparated from all elements except hafnium as insoluble phenyl-arsinate from a solution containing 10% hydrochloric or sulphuricacid. The precipitate is ignited directly to zirconia. Double pre-cipitation is necessary for the complete separation from thorium,uranium, phosphoric acid, and iron.Thorium phenylarsinate isthe only rare-earth salt of the acid insoluble in excess of acetic acidand this is used in tho application of this reagent to the analysis ofmonazite.81 Zirconium citrate, although soluble in ammonia orcitric acid solution, is only sparingly soluble in water, whilst hafniumcitrate is readily soluble.s2 Zirconium hydroxide is soluble inammonium carbonate solution a t 70' ; this property has beenapplied to the separation from iron and aluminium. Thorium, ifpresent, accompanies the zirc0nium.8~ Niobium (columbium) canbe determined in the presence of tantalum by reducing it withhydrogen to the tetroxide and ascertaining the increase in weighton ignition; tantalum pentoxide is not reduced.The black colourof the tetroxide is a sensitive qualitative test for ni0kium.8~Palladium may be separated from the other platinum metals andfrom the commoner metals by means of benzoylmethylglyoxime.Precipitation is carried out in acid solution, with certain precautionsif antimony, molybdenum, vanadium, or tungsten is present.85ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.76 W. Strecker and P. de la Pefia, 2. anal. Chem., 1925,67,256 ; A,, 1936,262.7 7 A. J. Berry, Analyst, 1926, 51, 137; A., 376.78 E. Zintl and G. Rienacker, 2. anorg. Chem., 1926,153, 276; A,, 703.G. E. F. Lundell and H. B. Knowles, J. Amer. Chem. Soc., 1925, 47,2637; B., 1926, 1016.8o E. Isnard, Bull. Sci. Pharm., 1925, 32, 131.A.C. Rice, H. C. Fogg, and C. James, J . Amer. Chem. SOC., 1926, 48,D. H. Drophy and W. P. Davey, Physical Rev., 1925, [ii], 25, 882; A,,R. Lessing, Z. and. Chem., 1925, 67, 341; A., 1926, 263.0. Ruff and F. Thomas, 2. attorg. Chem., 1926, 156, 213; A., 1222.J. Hand, A. Jilek, and J. Lukas, Chem. News, 1925, 131, 401; 1926,895; A,, 593.1926, 1117.132, 1; Chsm. &sty, 1926, 20, 68, 133; A,, 141ANALYTICAL CHEMISTRY. 195Titanous sulphte in the cold reduces salts of gold, palladium, andplatinum (and some base metals) t o the metallic state and thuseffects a separation from iridium; a method for the separation ofplatinum and rhodium depending upon this reduction is given.86The treatment of the iridium-ruthenium-iron alloy (obtained afterextraction of a lead button) necessary to isolate the iridium isdescribed in detail.87Except in very small concentrations of the metal, the brownish-red colour produced by hydrogen peroxide with solutions ofmolybdic acid containing excess of sodium hydroxide can beused, under certain conditions, for the determination of molyb-denum.Ammonium salts must first be removed by boiling thesolution with sodium hydroxide.88 A solution of quinquevalentvanadium in phosphoric acid is reduced quantitatively by theaddition of potassium iodide to the quadrivalent state, with liber-ation of the equivalent amount of iodine.89Tellurium is completely precipitated as the element by boilingits solutions in alkali sulphides with sodium sulphite ; in the presenceof potassium cyanide, separation from gold, copper, and seleniumcan be effected.Lead, bismuth, and mercury must f i s t be removedby appropriate methods.g0 Solutions of selenious or tellurous acidcan be determined in the absence of hydrochloric acid, by titrationwith permanganate in the presence of disodium phosphate ; if thetwo elements are present together, the tellurium is determined firstof all by dichromate.91In the absence of heavy metals, small quantities of bromides,chlorides, cyanides, and thiocyanates may be titrated with mercuricnitrate, sodium nitroprusside being used as indicator and theTyndall effect being employed to observe the end-point. Themethod is applied to perchloric acid after reducing it by means oftitanous sulphate and oxidising the excess with ammonium per-sulphate.92 Comparison has been made of several methods ofevaluating perchloratesg3 and full details for conversion into chloridewithout loss of chlorine by heating with sodium carbonate areI.Wade and T. Nakazono, Sci. Papers Inst. Phys. Chem. Res., 1923,W. R. Schoeller, Analyst, 1926, 61, 392; A., 931.A. D. Funck, 2. anal. Chem., 1926, 68, 283; A,, 815.8D T. Heczko, ibid., p. 461; A., 1926, 1020.A. Brukl and W. Maxymowicz, ibid., p. 14; A., 1926, 490.* l W. T. Schrenk and B. L. Browning, J . Amcr. Chem. SOC., 1926, 48, 2550;p2 I?. Konig, 2. anal. Chem., 1926, 88, 385; A., 1017.1, 139; A., 1926, 141.A., 1115.D. Dobroserdov, Ukraine Chem. J . , 1926, 2, 1 ; A,, 928196 ANNUAL REPORTS ox THE PROGRESS OF CHEMISTRY.givenaQ4 This reduction may also be effective by fusion with sodiumnitrate and gradual addition of copper powder.95Small quantities of iodide, bromide, and chloride may be estimatedwith fair accuracy when present together by releasing the halogensone a t a time by increasingly powerful oxidising agents.Thoseselected are acid ferric sulphrtte for iodine, cold chromic anhydridefor bromine, and permanganic acid for chlorine, the halogens beingremoved by aspiration after treatment.90 Iodides may be titrateddirectly in sulphuric or phosphoric acid solution by permanganate,ethyl acetate being present to extract the iodine liberated, therebyenabling the end-point to be discerned ; manganous sulphate mustbe added if bromides and chlorides are also pre~ent.~'The exact determination of fluorine is a matter of considerabledifficulty and continues to attract attention.The ordinaryBerzelius method depending upon the precipitation of calciumfluoride always gives low results and quantities of the order of0.1% may be missed entirely.For the small amounts found in rocks, the method of G. Steiger,QButilising the bleaching effect of fluorides in acid solution on theyellow colour produced by hydrogen peroxide with titanium sulphate,is well adapted for use. Calibration curves must be constructedfor this method and precautions taken as regards the concentrationof alkali sulphate, acidity, and temperat~re.~~ G. Starck showedthat with soluble fluorides it is possible to utilise the insolubilityof PbFCl for the determination.He found that saturated leadchloride solution effected complete separation from the neutralsolution ; the precipitate was granular and readily filtered andother salts which did not affect lead exerted no influence. Thismethod has been applied to the determination of fluorine in ores oflow or medium fluorine content. The ore is fused with fusionmixture, sulphur is oxidised by sodium peroxide, and the melt isextracted with aqueous sodium carbonate. Some hydrochloric acidis added and the neutralisation is then completed with nitric acid.PbFC1 is precipitated by means of lead acetate containing aceticacid. The precipitate is filtered off, washed, and redissolved innitric acid and the chlorine contained is determined by a suitableD.Dobroserdov andV. Erdmann, Ukraine Chem. J., 1926,2, 16; A., 927.96 K. Kurschner and K. Scharrer, 2. anal. Chem., 1926, 68, 1 ; A.,9 6 P. L. Hibbard, Id. Ens. Chem., 1926, 18, 67, 836; A., 260, 928.9' F. L. Hahn and H. Wolf, Chem.-Zlg., 1926, 50, 674; A., 1220.98 J . Amer. Chem. Soc., 1908, 30, 219.98 H. E. Merwin, Amer. J . IS&., 1909, [ii], 28, 119.490.12. anorg. Chm., 1911, 70, 173; A . , 1911, ii, 436ANALYTICAL CHEMISTRY. 197method. It was found that zinc, sulphates, and phosphates havebut little effect on the result.8A method used by A. Greeff 8 depends upon the fact that theaddition of ferric chloride to a neutral solution of fluoride producesa white or faintly buff-coloured precipitate of M,FeF,. TO theneutral solution of the fluoride, salt and a strong solution of potass-ium thiocyanate are added and the fluid is titrated with ferricchloride solution until a weak yellow colour persists.The end-point is improved by adding sufficient of a mixture of equal partsof alcohol and ether to the aqueous solution and titrating withferric chloride until the red colour persists in the ether layer.4The insolubility of thorium fluoride, ThF4,4H,0, in very dilutenitric acid or in acetic acid 5 provides a method by which as littleas 0.01% of fluorine may be detected. The process consists inadding a slight excess of thorium nitrate to the solution, justacidified with nitric or acetic acid. The precipitate is igniteddirectly to thorium oxide.Phosphates must f i s t be separated inthe usual way, whereas silicofluorides precipitate their fluorinedirectly and can be estimated. I n this process the acidity is bestkept within the limits of 3 / b to 3/50 of acetic acid.6The difficulties of fluorine determination in basic slag due to thepresence of phosphates and vanadium have been surmounted byfusion, extraction of the melt, neutralisation, and treatment withsolid silver sulphate. The last operation and also the atration ofthe precipitated phosphate and vanadate are conducted in thedark. The fluorine is then determined colorimetrically a t 19" to36" by the bleaching effect on an acid solution of titanium sulphatecontaining hydrogen peroxide. Curves are drawn connecting bleach-ing effect with concentration of fluorine, up t o 25 mg.of fl~orine.~This process is clearly applicable to other phosphates.Another colorimetric method for fluorine depends on the bleachingof the blue lake produced by zirconium oxychloride with sodiumalizarinsulphonate in hydrochloric acid. The fluoride, if notalready in solution, is obtained from insoluble fluoride by digestionon a water-bath with 10% zirconium oxychloride solution to whichis added an equal volume of concentrated hydrochloric acid and* F. G. Hawley, Ind. Eng. Chem., 1926, 18, 573; B., 1926, 672.1. See a180 W. D. Treadwell and A. Kohl, Helv. Chim. AcEa, 1926, 8, 600;Ber., 1913, 46, 2511; A., 1913, ii, 97E.A . , 1926, ii, 1197.F. Pisani, Compb. rend., 1916, 162, 791; A., 1916, ii, 393.(I F.A. Gooch and M. Koboyashi, Amar. J . LSci., 1918, [iv], 45, 370; A.,R. G . Warren, C. T. Imminghem, and H. J. Page, J. Agric. Sci., 1925,1918, ii, 177.15, 616198 ANNO& REPORTS ON THE PROGRESS OF CHEMISTRY.1 C.C. of a 0.03% solution of sodium alizarinsulphonate. A similarsolution is prepared without fluoride and both solutions are dilutedto a suitable bulk. Both solutions are then titrated with standardpotassium fluoride until the orange tint is the same. The methodapplies to fluoborates, fluotitanates, fluosilicates, and fluoalumin-atesa8 It is shown that optimum precipitation as, e.g., calciumfluoride occurs in the presence of excess of an alkaline-earth ion ofconcentration 0.027 mol./litre. The addition of a little ferricchloride and some ferrous salt to a fluoride which is to be titratedby using aluminium chloride enables a satisfactory end-point to beobtained in the potentiometric titration.9The azidodithiocarbonate radical, -S*CSN,, resembles the halidesanalytically, Volhard’s method affording the best results.1°A colorimetric method for the determination of minute quantitiesof hydroxylamine, based on the reaction with benzoyl chloridefollowed by addition of ferric chloride, has been described.11Some convenient volumetric process for determining sulphateswould be of great advantage generally.It is found l2 that excessbarium chloride may be titrated with standard potassium stearateand B.D.H. “ universal ” indicator, the solution reacting alkalineas soon as all the barium has been precipitated as stearate.Un-fortunately, the method breaks down in the presence of 1% or moreof neutral salts, which affect the end-point in either direction.13I n a similar process, the excess barium chloride is estimated bytitration with standard potassium chromate until the solutionbecomes alkaline to methyl-red.14 Precipitated benzidine sulphatemay be titrated with sodium hydroxide ; and a modified procedurenecessary in the presence of lead is des~ribed.1~ For the micro-determination of sulphuric acid, it is recommended to bring aboutthe precipitation with barium chloride in the presence of traces ofcolloidal celluloid, which cause rapid flocculation of the bariumsulphate. The method of preparing the celluloid is described andit is stated that adsorption of barium chloride is negligible with thesmall quantities used in micro-analysis.16J. H.de Boer and J. Basart, 2. anorg. Chem., 1926, 126, 213; A., 690.W. D. Treadwell and A. Kohl, HeEv. Chim. Acfa, 1926, 9, 470; A., 701.lo A. W. Browne and G . B. L. Smith, J . Amer. Chem. SOC., 1926, 47, 2898;l1 G. W. Pucher and H. A. Day, J. Amer. Chem. Soc., 1926,48,672; A., 490.l2 H. Atkinson, AnaEyst, 1925, 50, 690; A., 1926, 38; ibid., 1926, 51, 140;A,, 1926, 39.B., 358.Idem, ibid., 1926, 61, S1; A., 261.l4 A. A. B r i d , 2. amrg. Chern., 1926,156, 210; A., 1221.l5 Vlastimii and M. Matula, Chem-Ztg., 1926, 50, 486; A., 928.l8 E. Eigenberger, 2. anal. Chem., 1920, 68, 220; A., 701ANALYTIOAL CHEMISTRY.199Two methods of procedure for the permanganate titration ofhypophosphorous acid and its salts, and the precautions for pre-venting undesirable reduction of the permanganate, have beeninve~3tigated.l~Water Analysis.Free chlorine may be detected and determined in water for drink-ing purposes by means of the red colour developed on treatmentwith acetic acid and then with dimethyl-p-phenylenediamine.The comparison is made with standard iodine solutions treatedsimilarly.l* The sensitivities of the o-tolidine and the starch-iodide test for chlorine have been c0mpared.1~ For the determin-ation of iodides in natural waters, a method depending on oxidationto iodate by means of hypochlorite has been worked out ; additionof potassium iodide to the acid solution then results in the liberationof a quantity of iodine six times as great as that originally presentas iodide.20The somewhat high values found by titration for the carbonicacid concentration of distilled water are due to improperly neutral-ised indicators and to the slowness with which the carbon dioxideescapes into the atmosphere ; the requisite conditions for this deter-mination areThe methods for the determination of dissolved oxygen havebeen critically reviewed ; 23 treatment with ferricyanide, hypo-chlorite, permanganate, carbamide, or azoimide for the purposeof eliminating interfering oxidisable impurities is not consideredto be of general value.A new method is advanced using brominefor the oxidation of interfering substances, the excess being removedby salicylic acid ; Winkler's method, unmodified, is then applied.Apparatus for this determination has been adapted so that onlysmall quantities of water are required.23Methyl-red is not a suitable indicator for ascertaining thehydrogen-ion concentration of waters approaching neutrality ; fordistilled water, the sodium salt of methyl-red or of chlorophenol-red is better, but the most accurate indicator is heptamethoxy-17 D.Koszegi, 2. anal. Chem., 1926, 68, 216; A., 7 0 2 ; I. 11, Kolthoff, ibid.,16 I. &I. Kolthoff, Chein. Weekblad, 1926, 23, 203; B., 517.19 A, M. Buswell and C. S. Bomff, J . Amer. lYuter Works Assoc., 1925, 14.384: B,, 1926, 174.20 H. W. Brubaker, H.S. van Blarcom, end N. H. Walker, J. Amer. Chem.soc., 1926, 48, 1502; B., 630.21 I. RI. Kolthoff, Biochem. Z., 1926, 176, 101; A,, 1116; Chenz. Weekblud,1926, 23, 381 ; A., 1018.2 2 G. Alsterberg, Biocham. Z., 1926, 170, 30; A., 591.28 C. Risch, zbad., 1925, 161, 465; A.. 1926, 140.1926, 6Q, 36; A,, 1018200 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.triphenyl~arbinol.~~ For such unbuffered solutions, bromothymol-blue should be adjusted to a pure dark green colour by addition ofalkali ; since, however, this solution is not stable, a neutral solutionof p-nitrophenol is preferred.25A series of solutions of pE values ranging from 12.5 to 2 andcalibrated by means of the quinhydrone electrode has been preparedin a medium consisting of acetone and water (9 : 1 by volume) ; thecolour changes of a large number of indicators with these solutionsand with water are tabulated.26 Permanent standards preparedfrom potassium chromate and dichromate are recommended forcomparison with nitro- and dinitro-phenols in the determinationof hydrogen-ion c~ncentration.~~ The use of methyl-orange ordimethyl-yellow gives slightly high pE values with the hydrogenphthalate series of solutions, for which bromophenol-blue or methyl-red is better suited; the Sorensen series of citrate solutions arerecommended for use with methyl-orange.28 Standard alkalinebuffers produce with some indicators a salt error which in extremecases may amount to two units as compared with the pH valuesof sodium hydroxide solutions.29Gas Analysis.For the colorimetric determination of free chlorine in air by theuse of o-tolidine, comparison is made with a series of standardsmade by mixing dilute solutions of copper sulphate and potassiumdichromate.30 A study of the concentrations of cuprous chloridenecessary to obtain maximum absorption of carbon monoxideshows that the ammoniacal solutions are more efficient than acidsolutions?l In a review of the various methods for the detectionand determination of carbon monoxide in small concentrations, itis shown that accurate quantitative results are obtained only bycombustion.With practice, however, the time required to producea coloration with ammonium chloropalladite or with ammoniacalsilver nitrate affords a fairly accurate measure of the concentrationof the gas in ahas224 I.M. Kolthoff, Chem. Weekblad, 1926, 22, 690; A,, 1926, 139.26 H. T. Stern, J. BioZ. Chem., 1926, 05, 677; A,, 1926, 38.*a F. M. Cray and G. M. Westrip, Trans. Paraday Soc., 1926, 21, 326; A,,27 A. Janke and S. Kropacay, Biochem. Z., 1928,174, 120; A., 927.28 I. M. Kolthoff, Rec. ~ a v . chim., 1926, 45, 433; A,, 701.29 J. W. MoBain, 0. E. Dubois, and K. G. Hay, J . Gem. Phyaiol., 1926, g,80 L. E. Porter, Ind. Eng. Chem., 1926, 18, 730; A,, 927.81 L. Moser and F. Hanika, 2. anal. Chem., 1926, 67, 448; A,, 376;.s* H. Kast and H. Selle, Qua- u. Wasserfach, 1926, 09, 812; A,, 1018.1926, 374.461; A., 690ANALYTICAL CHEMISTRY. 201Organic Analysis.Quditative.-A large number of qualitative tests for formalde-hyde have been critically examined with the view of ascertainingthose best suited for the detection of small quantities, particularlyin the presence of such substances as acetaldehyde, furfuraldehyde,and carbohydrates.Primary alkyl bromides and iodides are readily converted intothe corresponding mercuric alkyl halides, which are well-definedsubstances suitable for purposes of identification."4 The mono-substituted acetylenes also may be identified by the formation ofcharacteristic mercury derivatives, (CRE3&Hg.363 : 6-Dinitrobanzoyl chloride is particularly suitable as a reagentfor alcohols ; the esters form definite molecular compounds witha-naphthylamine.A number of esters from anthraquinone-p-carboxyl chloride are also describedF6 u-Naphthylcarbimide reactsreadily with primary and secondary alcohols, less readily withtertiary, giving urethane derivatives?' Examination of the pro-ducts of reaction of their toluenesulphonates with ammonia, amines,or hydrazine enables a distinction to be made between primaryalcohols, secondary alcohols, and phenols.38A review of the colorimetric tests for lactic acid depending uponthe formation of acetaldehyde and subsequent reaction with phenolsshows that these are, in general, not very trustworthy.Phloro-glucinol and p-cresol are the most sensitive phenols. Methods forthe isolation and identification of the acid in gastric juices aregi~en.3~ The purple colour of the ferric salicylate complex ischanged by the addition of minute quantities of substances capableof repressing the ferric ion, and a method of testing for the'absenceof citrates or tartrates is based on this effe~t.4~The red colour given by quinine on addition of bromine andphenylhydrazine hydrochloride followed by ammonia is not shownby other common alkaloids.It is inhibited by alkalis, morphine,codeine, and excess of reagent~.~l Either benzidine or citric acid38 T. Sabalitschka and C. Harnisch, Phurm. Zentr., 1926, 67, 289, 309, 324,339, 357, 371, 387; A,, 853.s4 C. S. MarveI, C: G. Gauerke, and E. L. Hill, J . Amer. Chem. ij'oc., 1925,47, 3009; A., 1926, 144.36 J. R. Johnson and W. L. McEwen, ibid., 1926, 48, 469; A., 495.36 T. Reiohstein, Helu. Chint. Actu, 1926, 9, 799, 803; A., 1225.3' V.T. Bickel and H. E. French, J . Amer. Chem. Soo., 1926, 48, 747; A,,I n each case the sensitivity is indicated.33617.K. Freudenberg and H. Hess, Annulen, 1926, 448, 121; A., 935.ID G. Capelli, Ann. Chim. Appl., 1925,16, 53; A., 1926, 632.J. B. Peterson, I d . Eng. Chem., 1926,17, 1146; A., 1926, 84.G. W. Hargreevee, J . Amer. Pharm. A~uoc., 1926, 15, 100; A., 967.0 202 ANNUAL REPORTS ON 'plw PROGRESS OF CHEMISTRY.in sulphuric acid solution gives with morphine and several relatedalkaloids a series of colour changes which may be extended bydilution and addition of ammonia.42 3 : 5-Dinitrobenzoic acid giveswell-defined, crystalline precipitates with some of the principalalkaloids and is recommended as a reagent for their recognition;photomicrographs are appended.@The characteristic colorations given with phosphomolybdic acidfollowed by ammonia constitute a sensitive reaction for distinguish-ing between 0-, m-, and p-dihydroxyphenols.MColour reactions for phenols are obtained by dusting sodiumnitroprusside over the surface of a solution standing over concen-trated sulphuric acid and shaking gently until the surface of contactbecomes coloured.45 a-Naphthylcarbimide reacts readily with hotmonohydric phenols and with aromatic amines, giving urethanesand carbamides, respectively.46Quantitative.-Modifications of the Kjeldahl method for nitrogen,employing copper powder or an iron-copper couple, have beendescribed which give good results with such compounds as phenyl-hydrazine, alkaloids, and pyrazolone ring compouiid~.~~ Othervariations of the method are de~cribed.~sAn apparatus is described for the determination of arsenic andof mercury in organic compounds by treatment in a current ofhydrogen, the elements being weighed as In the absenceof halogens, selenium may be determined in an organic compoundby the ordinary Carius combustion, whereby selenious acid isformed; this is estimated by titration with silver in the presenceof zinc oxide.60In the alkalimetric determination of formaldehyde by means ofsodium sulphite, thymolphthalein is a better indicator, particularlyfor dilute solutions, than phenolphthalein ; still better results areafforded by the latter indicator if the solution be saturated withsodium chloride before titration.51L.Ekkert, Pham. Zentr., 1926, 67, 498; A., 965.4a E. Navmo, Anal. Pis. Quh., 1926, 24, 283; A., 965.44 K. Brauer, Chem.-Ztg., 1926, 50, 663; A., 1036.46 L. Ekkert and L. W. Winkler, Pharm. Zen&., 1926, 07, 566; A,, 1033.46 H. E. FrencF and A. F. Wirtel, J . Amer. Chem. Sot., 1926, 48, 1736;47 K. Kiirschner, 2. anal. Chem., 1926, 08, 209; A., 702; see also K.48 A. C. Andersen and B. M. Jemen, ibid., 1926, 07, 427; A,, 375; A. EIek49 H. ter Meulen, Rec. trav. chim., 1926, 46, 364, 368; A., 490, 492.60 W. E. B r d t and R. E. Lyons, J. AM. Ohem. ism., 1926, 48, 2642; A.,51 IC. TLufel and C. Wagner, 2;. anal. Chem., 1928, 68, 26; A., 635.A,, 830.Kiirschner and K. Scharrer. ibid., p. 1 ; A., 490.and H.Sohotka, J. Amer. Chem. SOC., 1926, 48, 601; A., 632.1266ANALYTICAL CHEMISTRY. 203A convenient table has been constructed showing the relationbetween percentage, density, and freezing point of acetic acid forconcentrations of 90% and upwards; the disturbing effect of pro-pionic acid is discussed.52 A rapid thermometric method forevaluating acetic anhydride depends upon the reaction with aniline,toluene being used as a di1uent.B A gasometric method involvingthe decomposition of anhydrous oxalic acid in dry pyridine byacetic anhydride into carbon monoxide and dioxide has also beendescribed. 54A general method for the determination of the carbonyl groupdepends upon the conversion of the aldehyde or ketone into thecorresponding phenylhydrazone, the excess of phenylhydrazinebeing determined iod~metrically.~~ It is claimed that this methodis better than that of Benedikt and Strache ( A ., 1893, ii, 560),which employs Fehling’s solution. The isopropylidenedioxy-groupmay be determined by hydrolysis with hydrochloric acid; theliberated acetone is determined iod~metrically.~~Dehydration of alcohols may result in the formation of unsatur-ated hydrocarbons or cyclic hydrocarbons. The former may beestimated in the presence of the latter by the action of perbenzoicacid in chloroform solution.57 Dihydroxyacetone boiled withphosphomolybdic acid reduces it 180 times as rapidly as doesdextrose, thus permitting a colorimetric determination of thedihydroxyacetone in the presence of dextrose.58Conditions for the determination of diguanide gravimetrically asthe nickel derivative, Ni(C,H,N,),, have been worked out togetherwith the extra precautions rendered necessary by the presence ofguanylcarbamide.59Arginine in fairly acid solution is precipitated quantitatively byflavianic acid (2 : 4-dinitro-cr-naphthoI-7-sulphonie acid) even inpresence of histidine, and may be determined microchemicallyby this means.g0 The tryptophan content of proteins is readilyand accurately ascertained by means of the reaction with formalde-hyde and sulphuric acid.,1 A number of other papers also deal6* H. D. Richmond and E. H. England, Analyst, 1926, 51, 283; B., 646.68 H. D. Richmond and J. A. Eggleston, ibid., p. 281; B., 646.64 E. L.Whitford, J . Amer. Chern. SOC., 1925, 47, 2939; A., 1926, 189.6 6 E. G . R. Ardagh and J. G. Williams, ibid., p. 2983; Tram. Roy. SOC.I 6 A. Griin and R. Limpacher, Ber., 1926, 59, [B], 695; A., 632.S. Nasletkin and L. Briissoff, J. p . Ohm., 1926, [ii], lla, 169; A., 420.68 W. R. Campbell, J. Biol. Chem., 1926, 67, 69; A., 443.C. D. Carby, Id. Eng. Oh., 1926, 18, 819; A,, 1164.6o A. Kossel and W. Staudt, 2. gAysioE. Chem., 1926,156, 270; A., 967.J. Tillmans and A. Alt, Biochm. Z., 1925, 164, 136; A., 1926, 189Canada, 1926, [GI, 19, 111, 73; A., 1926, 189.0. Fiirth, ibid., 1926, 169, 117; A., 633204 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.with the determination of certain amino-acids.62 The precipitationof proteins, pure or impure, by means of trichloroacetic acid hasbeen investigated from the quantitative aspect.63Aldehyde sugars are completely oxidised t o the correspondingacids in the cold by excess of standard iodine in alkaline solution.642 : 4-Dibromophenylhydrazine furnishes a means of quantitativelyseparating galactose from xylose, , rhamnose, dextrose, lzevulose,maltose, and lactose, but not from arabinose.66Aromatic nitro-compounds may be determined by reduction inthe cold with titanous chloride in the presence of sodium citrate.After a short period, the excess of the reducing agent is estimatedeither potentiometrically by means of iron alum or volumetricallywith thiocyanate as indicator.66 An advantage claimed for thisprocedure is that chlorination of the nitro-compound does notoccur.Nitrobenzene is reduced by titanous chloride in presence ofsodium hydroxide ; the excess of titanous chloride is oxidised in air,and the resultant aniline estimated by the bromide-bromatemethod.67 A gasometric method of estimating primary aromaticamines is based upon diazotisation and decomposition in a nitro-meter of the diazo-compound with acid ferrous sulphate solution ;the nitric oxide formed is removed and the volume of nitrogenthen remaining is found to be equivalent to the amine present.68Aniline and similar aromatic amines may be accurately titratedpotentiometrically with sodium nitrite solution, an average potentialof + 0.58 volt a t the end-point being independent of the amine.6QIn the absence of free mineral acid, benzidine is completely pre-cipitated by mercuric chloride as benzidine mercurichloride ; con-versely, mercury is quantitatively precipitated by excess of benzidineacetate.70The oxidation of quinol by iodine is quantitative only if thehydrogen-ion concentration is less than 10-5N a t the end-point.Methods for the determination by chemical or potentiometric means62 M. T. Hanke, J . Bid. Chem., 1925, 66, 475, 489; A., 1926, 633; J. M.Looney, ibid., 1926, 69, 519; A., 1050; S. L. Jodidi, J . Amw. Chem. Soc.,1926, 48, 751; A., 636; Y. Okuda, J . Dept. Agric. Kyusha Univ., 1925, 1,163; A., 1926, 190.e3 F. B. Seibert, J . Bid. Chem., 1926, 70, 265; A., 1164.64 M. E. Pauchard, J . Pharm. Chim., 1926, 8, 248; A,, 535.'6 E. VotocBk, V.Ettel, and B. Koppovrt, BUZZ. Soc. chim., 1926, [iv], 39,( 0 I. M. Kolthoff and C. Robinson, Rec. Irav. chim., 1926, 45, 169;67 I. M. Kolthoff, Chern. Weekblad. 1925, 22, 558; A., 1926, 84.68 P. Grigorjev, 2. anal. Chem., 1926, 69, 47; A., 1049. *' E. Muller and E. Dachselt, 2. Elektrochem., 1925, 31, 662; A,, 1926, 314.70 W. Herzog, Chern.-Zig., 1926, 60, 642; A,, 1050.278; A., 601.A*, 420ANALYTICAL OHEMISTRY. 206are described, as well as the use of dichromate as the oxidisingagent.7fPhysical Methoh.A study of the absorption spectra of a large number of solutionsof different dyes has demonstrated that the width, B, of the absorp-tion band is connected with the concentration by the expressionB = Aed+y, where d is the thickness of the solution and A and yare constants for absorption bands.72 Absorption-spectra maximahave been listed for the azo-dyes obtained from a number of phenolsby coupling with pnitrobenzenediazonium chloride.73Magnesium electrodes are recommended for the production ofboth arc and spark spectra, since the magnesium lines between7000 and 3500 8.are not numerous and do not mask those of otherelements. 74 Data are given relating to the transmissive propertiesof the various types of spectral fllters employed for visible, ultra-violet, and infra-red radiation.75Details are given for the spectroscopic detection of extremelyminute quantities of mercury in vacuum tubes.76The quantity of ozone present in the atmosphere has been deter-mined by measuring the intensity of a number of Fraunhofer trans-mission lines in the region of the ultra-violet absorption band ofozone a t 3000 to 3300 A.77 Most inorganic substances exhibit nofluorescence or phosphorescence when examined in the ultra-violetlight (from a mercury arc) of wave-lengths 4400 to 2800AL., butmany salts do fluoresce.This test may be used to indicate certainimpurities.78The radio-micrometer has been used to measure the iodine con-tent of starch-iodide.79Small quantities of water may be determined in methyl alcohol,otherwise pure, by measuring the critical solution temperature ofthe sample with hexane.sOA simple X-ray spectrograph of the rotating-crystal type isdescribed,81 and details of a high-vacuum X-ray spectrometer withI.M. Kolthoff, Rec. truv. chim., 1926, 45, 745; A., 1266.J. Sebor, Chem. Listy, 1926, 20, 55, 174; A., 590.73 H. Wales and S. Palkin, J . Ame~. Chem. Soc., 1926, 48, 810; A., 615.E. Dureuil, Compt. rend., 1926, 182, 1020; A., 593.7 6 K. S. Gibson, J . Opt. SOC. Amer., 1926,13, 267; A., 1117.J. J. Manley, PTOC. Physical SOC., 1926, 38, 127; A., 376.7 7 G . M. B. Dobson and D. N. Harrison, Pfoc. Physical SOC., 1925, 38, 74;7 8 R. Robl, 2. angew. Chem., 1926, 39, 608; A., 701.7s J. Field and L. G. M. Baas-Becking, J . Oen. Physiol., 1926, 0,445; A., 590.M. M. Rising and J. S . Hioh, J. Amer. Chem. SOC., 1926, 48, 1929; A.,J. T. Xorton, J . Opt. SOC. Anw., 1926, la, 231; A., 1020.A., 1926, 140.967206 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.rotatory plate-holder end suitable crystal gratings for particularranges of wave-lengths are given.8aElectrochemical Methods.Electrolytic.-Polarisation curves of solutions of metals containingtraces of more noble metals from the electrochemical point of view,obtained with the aid of the dropping mercury cathode, show anumber of undulations the positions and dimensions of which arecharacteristic of the metallic impurities present.Various applic-ations of this process are described, which is sensitive to aboutlo-' g.-equivalent of metal per litre.@Copper free from cadmium may be deposited a t 1 amp. and 4 voltsby electrolysis with a rotating anode of a nitrate solution con-taining nitric, tartaric, and hydrofluoric acids,84 whilst completeseparation from bismuth is obtained by electrolysis a t 60" of asolution of the metals containing phosphoric acid.s5Conditions have been worked out for the electro-deposition ofantimony from hydrochloric acid solution containing hydrazinetmlphate.s6 Tellurium also may be rapidly determined by electro-lysis in a malonic acid solution containing ammonium sulphate andtartrate.8'Potenti0metric.-The reduction of compounds of the platinummetals to the metals by means of titanous chloride in acid solutionhas been followed potentiometricalIy ; very sharp end-points ereobtained with palladium and platinum.S8 Mercuric salts are reducedto metallic mercury by titanous chloride in hot acetic acid solution,containing ammonium chloride and also a bismuth salt 8s carrier.The method may be applied in the presence of arsenious, anti-monious, stannic, lead, cadmium, and bismuth salts and of smallquantities of iron salts.8B Iron may be determined, followingreduction with stannous chloride, in hydrochloric acid solution, bytitration a t 50" with standard potassium bromate in the presenceof cobalt chloride.The amount of bromate used in the oxidationis ascertained from the positions of the two turning points (stannousto stannic and ferrous to ferric) on the titration curve.B0 A similaraa M. Siegbahn and R. Thorreus, J . Opt. Soc. Amer., 1926,13, 236; A., 1020.84 A. Jilek and J. Lukas, ibid., p. 18; A., 262.86 W. Moldenhauer, 2. ungem. Chem., 1926, 39, 464; A., 692.86 A. Schleicher with L.Toussaint and P. H. Troquay, 2. and. Chem.,J. Heyrovskp, Chem. &9ty, 1926, 20, 122; A., 690.1926, 69, 39; A., 1020.J. Lukae and A. Jilek, Chem. Lisly, 1926, 20, 396; A., 1018.88 F. Miiller, 2. anal. Chent., 1926, 69, 167; A., 1222.89 E. Zintl and G. Rienilcker, 2. u w g . Chent., 1926,155, 84; A., 929.90 0. Collenberg and K. Sandved, ibid., 1926,149, 191; A., 1926, 140ANALYTICAL OHEMISTRY. 207method serves for the determination of gold, any aurous chloridepresent being first oxidised by addition of chlorine water; thesolution is then titrated against standard ferrous ~ u l p h a t e . ~ ~If the potentiometric titrations of cerous and cupric ions withpotassium ferrocyanide and of barium, lead, and mercurous ionswith potassium chromate are carried out a t 70" in a 30% ethyl-alcoholic medium, errors due to solubility of the precipitates andt o adsorption of ions thereon are eliminated and the potential a tthe end-point is rendered much sharper and steeper.92By suitable adjustment of conditions, it has been found possibleto effect progressive separation of iodide, bromide, and chloride(as the silver salts) from ammoniacal solution.93 Importantinvestigations and improvements in the potentiometric titrationof halides have also been made and Clark's method lends itself tothe accurate determination of the three halides in mixtures.94A platinum electrode, coated electrolytically with gold, is suitablefor the titration of oxidising acids.The results obtained withchromic, iodic, and periodic acids are described, the E.M.F.beinga linear function of the pE value of the acid, but varying withdifferent acids.95 In the determination of phosphates by titrationwith a uranyl solution in presence of acetic acid, the addition ofquinol or potassium ferrocyanide affords a sharper end-point.Alternatively] using a mercury electrode] titration may be carriedout a t 70" after addition of a known amount of mercurous sulphate,the fall in voltage a t the end-point being very sharp.s6Aromatic nitroso- and nitro-compounds may be titrated directlya t 50-80' with titanous chloride, alcohol being used as solventif necessary. The break in the curve is much more pronounced inpresence of Rochelle salt.97Attention is directed to the advantages of, and methods are givenfor using, the quinhydrone electrode in the measurement of hydrogen-ion concentration, by a number of authors.9sThe potential of a platinum electrode against a solution con-91 E. Miiller and F. Weisbrod, 2. anorg. Chem., 1926, 156, 17; A., 1117.'2 J. A. Athanitsiu, Compt. rend., 1926,182, 619; A., 376; J. Chim. phys.,OS H. T. S. Britton, Analyst, 1925, 50, 601; A., 1926, 39. *' W. Clerk, J . , 1926, 749 ; A., 590 ; E. Lange and E. Schwartz, 2. Elektro.* 5 L. Maleprade, Bull. SOC. chim., 1926, [iv], 39, 325; A., 490.* 6 S. Bodforas, Svensk Kern. T<dskr., 1925, 37, 296; A., 1926, 1018.1926, 23, 601; A., 929.chem., 1926, 32, 240; A,, 701.E. Dachselt, 2. anal. Chem., 1926, 68, 404; A., 1049.W. Ackermann, Collegium, 1926-1927.208; A,, 813; A. Hock, 2. angew.Chem., 1926, 39, 647; A., 701; C. W. 0. Hetteraohij and J. Hudig, Chem.Weekblacl, 1926, 23. 2; A,, 139; 5. B. O'Sullivm, Tram. Paraday Sac., 1925,21, 319; A., 1925, G, 822; L. Smolik, Biachem. Z., 1926, 172, 171; A., 927208 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.taining both ferrous and ferric ions is a function of the ratio of thetwo ions present under limiting conditions of concentration andacidity. If E, is the potential of the electrode against the acidalone and E that of the solution when iron salts are present, thena t 18" we have E = E, + 0.0577 log {[Fe*"]/[Fe"]). Hence the totaliron or the ferrous iron in a solution having been determined,measurement of the potential under standard conditions enablesthe proportion of each of the iron ions to be ascertainedag9 A newmethod for the conductometric analysis of weak acids and baseshas been described,l and also a method, applicable to iodometry,in which a P.D., between two platinum electrodes immersed in thewell-stirred iodine solution, of the same order as the polarisationE.M.F. is maintained.2Simple comparison electrodes for the titration of reducing sub-stances such as arsenious oxide and ferrous and vanadyl salts withpermanganate have been developed and details of the electrodesare furnished.3J. J. Box.B. A. ELLIS.se P. Hirsch and R. Ruter, 2. anal. Chem., 1926, 68, 328; A., 930.P. Hirach, ibid., p. 160; A., 700.C . W. Foulk and A. T. Bawden, J. Amer. Chem. SOC., 1926, 48, 2045; A.,927.a R. Lang, 2. Elektrochem., 1926, 32, 454; A., 1116

ISSN:0365-6217    

DOI:10.1039/AR9262300186

出版商:RSC    

年代:1926

数据来源: RSC

摘要:

BIOCHEMISTRY.THE material in this Report is arranged in the same manner asthaL adopted in the past two years : soil, plant, and animal bio-chemistry. I n one respect, however, an alteration has been made,Work on the physical and inorganic chemistry of the soil has beenomitted, in so far as questions of what may be termed pure soilchemistry are concerned. These have been left for discussion inthe Report by one of us on Soils and Fertilisers in the AnnualReports on Applied Chemistry. The soil problems dealt with inthis Report are those in which biochemical processes in the soilitself, or the relation of soil conditions to plant growth, are involved.There is no advance of outstanding importance to record, a tleast as far as soil and plant biochemistry are concerned.Sincethe war, great advances have been made in our knowledge of thechemistry of the soil, and we appear now to have reached the stagewhere the new points of view are being consolidated and mattersof detail are being cleared up, in preparation for further advances.With regard to plant chemistry, we are still groping in the darkwithout any very clear indication of the direction in whioh fruitfuladvances in knowledge are to be found.The Humic Matter of the 8oil.I n the Reports for 1924 and 1925,l the lignin hypothesis of theorigin of humic matter, the detailed development of which is due toF. Fischer and his co-workers, was discussed. This hypothesiscontinues to gain ground. One type of evidence on. which thishypothesis rests is that depending upon the analysis of plant materialin various stages of humification. Further evidence of this typehas been advanced during the past year by W.Grosskopf and byS. Odkn and S. Lir~dberg.~ The former investigator analysedsuccessive layers of the humic soil in a pine wood. He found amarked relationship between the loss of lignin and the formationof humic matter. The latter was determined by making use of thesolvent action of acetyl bromide, which is stated to dissolve com-pletely all undecomposed plant materials. Odkn and Lindberghave similarly analysed a number of peats of varying age. Theyfound that cellulose gradually disappears and that the sum of1 Ann. Reports, 1924, 21, 172; 1925, 22, 206.2 See also F. Fischer, 2. Deuts.Ceol. Oes., 1925, A, 77, 534; B., 1926, 393.3 Brennstof-Chenz., 1926, 7, 293; B., 939.4 Ibid., p. 165; B., 668.20210 ANKUAL REPORTS ON THE PROGRESS O F CHEMISTRY.lignin plus humic substances remains more or less constant : asthe lignin content falls, humic matter takes its place. From con-siderations based on P. Klason’s views on the constitution of l i eand Eller’s views on the chemical nature of the process of humusformation, they develop a hypothesis for the structural relationshipof humic acid to lignin. It is supposed that the coniferyl par-aldehyde unit of lignin is converted into a conjugated furan deriv-ative by internal condensation thus ;CHHThere is Borne evidence for the presence of furan nuclei in lignin andhumic acid.By simultaneous oxidation and reduction of a sub-stance of formula (1I);there could be produced the acid (111), con-taining two phenolic hydroxyl groups in the ortho-position. Inan oxidising medium, o-dihydroxyphenols of this type readilyundergo condensation into a quinonoid substance thus :, .................... . ” - YOW -C*IOH H:O*C- I ( :--C*OIH HO$- c c .....................A O AThe production of a ring of this type is thought to be characteristicof the humification process, which involves the production of stronglycoloured products from oolourless ones. O d h and Lindbergsuggest structural formula for humic and ligno-humic acids involvingthe combination of units of structure (I), (11), and (111). Thusthey formulate a, ligno-humic acid built up from (11) and (111)and a humic acid built up from two units of formula (111) thus :Me C0,H C0,H C02HLigno-humic acid.Humic acid.See Ann. Report, 1923, 20, 209BIOCEEMISTRY. 211Formula (IV) corresponds to an equivalent weight of 322, whilst(V) has an equivalent weight of 362 or 176 according as i t behavesa8 a mono- or a di-basic acid. OdBn’s earlier determination of theequivalent weight of natural humic acid from peat gave the value330-345, whilst the value calculated by Hissink from the exchange-able base content of ‘‘ saturated ” humio soils is 176.These speculations are interesting in that they combine the viewsof Eller and Fischer, but the present position of the subject doesnot warrant their being regarded as anything more than speculations.H. Strache and A.Brandl have determined the carbonyl contentof lignin, humic acid, and coal by treatment with phenylhydrazineand determination of the excess of the latter with Fehling’s solution.Lignin contained only 0.2%, whilst humic acid from lignite contained3.2%. The subsequent conversion of lignite into coal involved afall in the carbonyl content, anthracite containing only 1%. Itwill be noticed that there are no carbonyl groups in the formulsproposed by OdBn.S. A. Waksman has published a series of papers dealing with theorigin and nature of the humic matter of the soil. The fist of thesepapers consists of a comprehensive review of the literature of thesubject, The lack of satisfactory methods of characterising humiamatter is emphasised, and it is pointed out that many of the productsreferred to loosely as humus, humic acid, etc., are undoubtedly nothomogeneous ; many of the conflicting statements in the literatureare due to this fact.In another paper of the series, it is shown thatof the various constituents of straw the lignins are the most resistantto the action of fungi and bacteria. Thus they tend to accumulatein the soil, and in Waksman’s view they constitute a considerablepart of the soil humic matter. If lignins are removed from straw orlucerne meal, the rate of decomposition of the material is hastenedand the amount of residual matter is greatly reduced. It wasfound that when lignin was introduced into the soil it could berecovered almost quantitatively, after incubation, as “ humus.”As pointed out in last year’s Report,* the nitrogen content of thehumic matter of the soil is not explained by current hypothesesas to the origin of the latter.In that Report attention was directedto Waksman’s views on this subject, which are still further developedin the papers now under notice, and to the work of Hobson on thestate of the nitrogen in humic acid.The possibility still exists that the humic matter of soil may be of’ S. A. Waksman, SaiESci., 1926, 22, 123, 323; B., 1926, 892, 990; S. A.Brennatoff-chem., 1926, ’7, 341.Waksman and F. 0. Tenney, ibid., p. 396; S. A. Waksman, ibid., p. 421.Ann. Report, 1925, 22, 208212 ANNUAL REPORTS ON THE PROGRESS OB CHEMISTRY.8 two-fold character.The work of A. C. Thaysen, W. E. Bakes,and H. J. Bunker 9 supports this view. These workers found thatthe humic matter which constituted a high proportion of an ancientEgyptian linen cloth yielded a chlorine derivative very similar tothat obtained from Eller’s artificial humic acid. The humic com-pounds from peat, however, gave on chlorination a mixture ofsubstances partly soluble in ether. The ether-soluble fraction wassimilar to the chlorine derivative obtained from lignin humic acid,whilst the ether-insoluble fraction resembled the chlorine derivativeof the artificial humic acid obtainable from sugar or cellulose.J. Marcusson,lQ who has hitherto been a firm supporter of thecellulose hypothesis of the origin of humic matter and coal, nowbelieves that both lignin and cellulose are concerned in the process.C.G. Schwalbe and R. Schepp,ll however, still favour the cellulosehypothesis. They describe the production of humic products andof “ coal-like ’’ substances by the action of oxalic acid and magnesiumchloride on cellulose, sugars, and wood; sugars are regarded as anintermediate phase in the process. Bergius’s results on the artificialproduction of coal from cellulose and lignin have been criticised byH. Tropsch and A. von Philippovich l2 on the grounda that Bergiusneglected to consider the appreciable formation of water-solubleproducts in his experiments. Further progress in this field of workis hindered by the scanty knowledge of the chemical nature of lignin.A considerable amount of work is, however, now being carried outon this subject.Two valuable monographs on lignin by W. Fuchs l3and by Kurschner 14 have recently appeared (see also p. 230).Carbon and Nitrogen Transformations in the Soil.It is generally recognised that the application of lime or chalkto the soil hastens the decomposition of organic matter, althoughthe view that the action of lime in this respect is greater than thatof chalk was shown t o be untenable by J. W. White and F. J.Holben15 on re-examination of the data from the plots of thecontinuous manurial experiment in Pennsylvania. A furtherexamination of these data shows that on soil regularly carryingcrops in rotation the effect of treatment with lime is actually t o* Biochem.J . , 1926, 20, 210.lo 2. angew. Chem., 1926, 39, 898; B., 809.l1 Ber., 1925, 68, 2500; B., 1926, 145.1’ Abhandl. Kennt. Kohle, 1925, 7, 84; B., 1926, 858.1* “ Die Chemie des Lignins ” (Berlin), J. Springer, 1926.l6 Soil Sci., 1925, 20, 313; B., 1926, 26.‘‘ Zur Chemie der Lignb Korper ” (Stuttgart), F. Enke, 1925. 116 pp.See oleo Ann. Rep. Appl. Chem.,1924, 0, 438BIOCHEMISTRY. 213cause an increase in the organic matter content of the soil. This isdue to the fact that the use of lime, by liberating more plant nutrientsfrom the dung which is added a t the same time, gives rise to muchlarger crops and thus to much larger crop residues (stubble, etc.).The organic matter left in the soil by the decomposition of theseresidues more than counterbalances the increased loss in organicmatter of the added dung caused by the action of the lime.M.Bachlo has studied the rate of oxidation of the carbon offarmyard manure which has been added to the soil. As an averageof the results obtained with various types of soil, he found that75% of the added carbon disappeared from the soil in the first year.The loss of pentosans was even more rapid than this, but the lossof lignin was much slower.On the addition of carbohydrate material to the soil, the pro-duction of carbon dioxide as a result of the action of micro-organismsrises t o a maximum and then falls. D. V. Bal has made a studyof this action in the case of Bacillus prodigiosus. He found that thefall in carbon dioxide production occurred despite the fact thatthere was still present a residue of undecomposed sugar and ofsufficient of the other nutrient materials required by the organism.Nevertheless, the addition of a further supply of sugar causedcarbon dioxide production again to rise and this effect could beobtained repeatedly by further additions of sugar.This curiousresult may be in some way connected with the production of toxicby-products by the organism, but further work is needed to establishthis.B. M. Bristol-Roach,ls in an investigation of the relation ofcertain soil alga to various carbohydrates and related compounds,has demonstrated the ability of soil algse to grow in the dark if asuitable supply of organic food is provided. These alga are thusable to function either auto-trophically as green plants in the lightor hetero-trophically, in the same manner as fungi and most bacteria,in the dark.Their auto-trophic activity can be of little signifhncein most soils, since it could only occur at the surface (although thiseffect is of considerable importance in the gaseous exchanges ofwater-logged soils in the tropics), but the possession of the power ofliving saprophytically in the interior of the soil renders soil algaea factor which must be taken into consideration in studying thebiochemical changes of the soil.S. A. Wakaman and C . E. Skinner have studied the micro-ls Landw. Vera.-Stat., 1926, 104, 245; B., 640.l7 Ann. Appl. Biol., 1926, 13, 231.18 Ann. Bot., 1926, 40, 149.19 J . Bact..1926, 12, 57214 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.organisms concerned in the decomposition of celluloses in the soil.They conclude that under anaikobic conditions and in humid soilsthe fungi are largely concerned in the process, but that in and andalkaline soils the aerobic bacteria play an important part. Underanaerobic conditions, bacteria are the only organisms concerned.This is true, not only of soils, but probably also of the decompositionof celluloses in all natural processes. Although some actinomycetesare capable of decomposing cellulose, they do not seem to play anydirect part in this process in the soil ; their action is largely limitedto the secondary products. As already shown by earlier work byWaksmanZ0 and by other investigators, the extent of the decom-position of cellulose is dependent on the supply of available nitrogencompounds, but this decomposition goes on to a greater extent inanaerobic than in drobic conditions for a given supply of availablenitrogen, since under anaerobic conditions a much smaller amountof energy is liberated and utilised by the organisms.Furtherresults on the relation between available nitrogen and cellulosedecomposition are reported by J. A. Anderson21; the maximumdecomposition of cellulose was found t o occur when the proportionof nitrogen t o cellulose equalled or exceeded 1 : 35. Nitrification isnot prevented by the presence of cellulose, but the nitrate producedis utilised by the organisms as soon as it is formed.Ammoniacan be used by the organisms directly.The effect of the relation between available nitrogen and ferment-able carbohydrate material on the presence of nitrates in the soiland their supply t o the growing plant, as well as the bearing of thisfactor on the carbon : nitrogen ratio of the soil, has been discussedin these Reports for 1923 and 1925,22 and subsequent work has addedlittle t o our knowledge of the position as there set forth. T. L.Lyon,zS in a paper read a t the symposium on soil bacteriology-nitrification studie,eheld by the American Society of Agronomyat Chicago in November, 1925, has given a, useful summary of thisquestion. C. Barthel and N. Bengtsson24 have shown how thesame factor operates in the breakdown of roots and stubble in thesoil; thus oat-straw contains enough nitrogen t o supply the needsof the bacteria responsible for its decomposition, so that it rots morequickly than pure cellulose in sandy soils of low nitrogen content.Similarly, R.P. Thomas and H. J. Harper 25 have shown that1 0 Ann. Report, 1925, 22, 207. Soil Sci., 1926, 21, 115; B., 457.22 Ann. Reports, 1923, 20, 213; 1925, 22, 207.** J . Amer. SOC. Agron., 1926, 18, 834. See also B. D. Wilson and J. K.z4 Mitt. 300 der Landw. Zentralversuchanst. (Sweden), 1926; Bakt.25 Soil Sci., 1926, 21, 393; B., 640.Wilson, Cornell Uniu. Agr. Expt. Sta. Memoir, 95. 1925.Abhandl., 40, 1; B., 640BIOCHEMISTRY, 215straw can be ploughed in after the second cut of a clover or legumeley without any harmful effect on the succeeding crop; the legu-minous residues supply suilicient nitrogen for the decompositionof the carbohydrates of the straw.R. C. Collison and R. J. Corn 26claim to have shown that the harmful effect of incorporating strawin the soil on the subsequent crop is due to two factors ; in additiont o the effect in reducing available nitrate, it is claimed that a toxicdecomposition product is formed from the straw.No satisfactory explanation has yet been advanced for theconsiderable Iosses of free nitrogen that occur in the manure heap,in sewage, and in soil receiving heavy dressings of dung. M. Lemoigneand P. L. Dopter 27 have isolated various bacteria from soil anddung which are capable of bringing about losses of nitrogen in purecultures.This loss occurs after their first rapid growth is over.Other papers dealing with nitrihation were read a t the above-mentioned symposium by W. A. Albrecht, A. L. Whiting, and H. J.Harper and B. Boatman.28 Albrecht showed how all normalcultivation operations have an augmenting effect on nitrate produc-tion in the soil but excessive cultivation or mulching with strawmay cause a decrease. A. L. Whiting has made a study of thefactors controlling the rate of nitritication of organic materials.This rate is greatest for water-soluble substances and for readilyhydrolysable compounds. Fresh green plant material producesnitrate more quickly than after drying. He gives a useful referencelist of more than 200 organic materials which have been classifiedaccording to their rate of nitrification, Harper and Boatman showthat the nitrification of sulphate of ammonia is more rapid when it isapplied in small than in large amounts.H. J. Harper 29 has alsoexamined a large number of soils with regard t o their ammoniacontent in relation to their reaction and their content of totalnitrogen and nitrates. He could find no correlation between thesefactors.Sulphur and Soil Fertility.Attention has been directed in recent Reports 30 to the effect ofsulphur oxidation on soil reaction and to the possible limitation offertility in some soils by deficiency of sulphur. R. H. Simon andp6 New York Agric. Exp. Btat., 1925, Tech. Bull. 114, 35 pp.; B., 1926,416.See also H. H. Hill, J . Agric. Res., 1926, 33, 77; B., 840.27 Cmpt.rend., 1926,183, 160; A., 979.s8 W. A. Albrecht, J. Amer. SOC. Agron., 1926, 18, 841; A. L. Whiting,ibid., p. 854; H. J. Harper and B. Boatman, ibid., p. 876.J . Agric. Res., 1925, 31, 649; B., 1926, 335.Ann. Repvrte, 1922, 19, 209, 213; 1923, 20, 214; Ann. Reports Appl.Chern., 1922, 7, 375; 1923, 8, 422216 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.C. J. Schollenberger 31 and R. E. Stephenson 32 have shown thatin the soil the rate of oxidation of sulphur depends in a markeddegree on its fineness of division. A. LeducB has reviewed theresults of various experiments indicating the influence of lackof sulphur on soil productiveness. From the investigations ofJ. M. Fife,34 it appears that the benefits obtained by the additionof sulphur to a soil very deficient in this element may be due, notonly to the direct influence of the supply of sulphur to the growingplant, but also to a beneficial effect on the micro-organisms concernedin ammonification and nitrification.When sulphur was added tosuch a soil containing an ample supply of all other nutrients exceptnitrogen, which was added in the form of dried blood, althoughthere was no rise in the numbers of bacteria developing on nutrientagar, oonsiderabIe increases in the production of ammonia andnitrates were observed. W. W. Johnston35 has shown that, on asemi-arid soil in Oregon which had been found to give crop increaseswhen treated with sulphur, the effect of cropping was t o decreasethe sulphate content, but that in humid soils cropping had thereverse effect.Thus the benefit or otherwise of sulphur additionsmay depend, not only on the sulphur content of the soil, but alsoon whether crop growth can stimulate sulphate formation enough tosupply the needs of the plant. It can on humid but not on semi-arid soils. J. R. Neller 36 has found that the addition of sulphuror gypsum to soil under greenhouse conditions caused an increasein yield and in the percentage of nitrogen in lucerne and clover.For the liberation of potash in an available form in the soil, sulphurwas found to be superior to gypsum by 0. M. Shedd.37 The additionof chalk favoured sulphur oxidation, but hindered liberation ofpotash,Plant Nutrition.Nitrogen Supply.-W.H. Appleton and H. B. Helms38 haveshown that the rate of absorption of sodium nitrate by oata andcotton when applied a t different stages of growth is the more rapidthe later the nitrate is applied. In both cases, there was a closecorrelation between the rate of growth and the rate of nitrogenuptake. The effect of the amount of nitrogen supplied, on thegrowth of the sunflower, has been studied by A. Rippel and 0.Ludwig ; 39 for smaller rates of nitrogen supply, the actual rate of(1 Soil Sci., 1925, 20, 443; B., 1926, 208.*a Ibid., 1926, 21, 489; B., 762.a4 Soil Sci., 1926, 21, 245; B., 600. 36 IbicE., p. 233; B., 457.36 Ind. Eng. Chcm., 1926, 18, 72; B., 208.8' Soil Sci., 1926, 22, 335.a8 J . Ainer. Soo. Agron., 1925, 17, 696; A., 1926, 871.39 Biochem.Z., 1926, 177, 318; A., 1280.83 Scientijc Agric., 1926, 0, 218BIOCHEMISTRY. 217growth is less, but in the first half of the growth curve the relativeproduction of dry matter and the relative absorption of nitrogenare greater with the smaller dressing. The same authors40 haveattempted to correlate the uptake of nitrogen with that of basesfor broad beans and oats grown in sand with or without the additionof combined nitrogen. The excess of nitrogen in the plants abovethat which could have been absorbed in the form of nitrates com-bined with the bases present in the plant (allowance being made forthe bases combined as phosphates and sulphates) is expressed as apercentage excess of nitrogen. As would be expected, this figureis much higher with broad beans when combined nitrogen is with-held.In the case of oats, the excess is still greater when nitrogenis given, whereas nitrogen-starved oats show a large excess of bases.T. W. Turner 41 has demonstrated the contrast between the responseof barley and make, compared with that of flax, to variations inthe nitrogen supply. The former two crops show large increasein the top : root ratio with increasing dressings of nitrate, which isdue to a stimulation of the growth of tops, not to a depression ofroot formation. In the case of flax this effect is not very marked.Beyond a certain low level of nitrogenous dressing, further increasesin nitrogen supply produce no appreciable change in the ratio oftop0 t o roots.No conclusive evidence is available regarding the benefit orotherwise of growing leguminous crops in association with non-legumes.J. H. Stallings 42 has demonstrated that wheat plantsgrown with soy-beans benefited, apparently by obtaining solublenitrogen compounds, from the latter. It is possible that this nitrogenwas obtained in the form of ammonia, which is the only form ofsoluble nitrogen that could be found in the growing soy-bean plants.Phosphate #upply.--It is known that the soil factors governingthe supply of phosphate to the growing plant are markedly differentfrom those concerned with the supply of most other nutrients.Much attention is being directed to this question at the presenttime. M. von WrangellP3 and her co-workers have published aseries of lengthy papers on this subject during the past year.Shedistinguishes three factors for the supply of phosphate from the soil :(1) the phosphate concentration of the soil solution; (2) the rateat which this concentration is restored after disturbance of theequilibrium between the soil and the soil solution; (3) the total40 Ber. DeU. bot. Oes., 1925, 48, 537; A., 1926, 439.‘1 Soil Sci., 1926, 21, 303; B., 601. Lp Ibk!., p. 253; B., 601.48 M. von Wrangell, Landw. Jahrb., 1926, 68, 627; M. von Wrengell andE. Kooh., ibid., p. 677; M. von Wrangell and W. Haase, ibid., p. 707; M. vonWrengell end L. Meyer, ibid., p. 739; B., 841, 842218 ANNUAL REPORTS ON THE PROGRESS or CHEMISTRY.reserve of soluble phosphate in the soil. The phosphate concentra-tion of the soil solution, obtained by the hydraulic press method,is regarded as being partioularly important because one is dealing,not only with an easily soluble material, but also with subgtances oflow solubility the concentration of which depends to a large extent onthe presence or absence of other ions.The phosphate concentrationin the soil solution varies between very wide Iimits for differentsoils. Raw subsoil and poor peat soils show values as low as 0.02 mg.P,O, per litre, whilst humic sandy soils and rich garden soils maygive values as high as 2 mg. or more per litre. The average valuefor most soils is from 0.1 t o 0.2 mg. per litre. I n any given soil,the phosphate concentration of the soil solution is relatively constantand varies little during the year, but according to Wrangell’s resultsit is a function of the moisture content of the soil, increasing withthe latter, This is explained by assuming that with increasedwater content there is an alteration in the structure of the soilparticles which renders the phosphates more soluble,It is considered that the characteristic phosphate concentrationof any given soil is determined more by the absorptive power of thatsoil than by any variation in the chemical nature of the phosphatereserves or of the phosphates added in the form of manure.Insupport of this view, it is shown that the solubility of the phosphatesof calcium, aluminium, and iron in water is much higher than thatrepresented by the phosphate concentration found in soil solutionsand is reduced to figures more comparable with the latter only bythe presence of lime.The rate a t which the phosphate Concentration of the soil solutionis restored sfter reduction of the latter was studied by Wrangell byexpressing the soil solution, then remoistening and again expressingthe soil solution after varying intervals. Some aoils show a rapidrate of readjustment, whilst in others the rate is very slow.Thisrate is determined by the amount of reserve phosphate in the soiland also by the absorptive power of the latter ; soils of low absorp-tive power give a much more rapid readjustment than do stronglyabsorptive soils.The total reserves of relatively soluble phosphate in the soil areregarded as the most important factor in the phosphate nutritionof crops.These reserves are determined by Wrangell by repeatedextractions of small quantities of soil with large volumes of waterand extrapolation of the curve showing the rate of falling off ofphosphate concentration in the successive extracts. The resultsshowed a good correlation with determinations of ‘ I available ”phosphate by Neubauer’s seedling method.In explanation of the claimed superioriby of the determinatioBIOCHEMISTRY. 219of total reserves of phosphate over that of the phosphate concen-tration of the soil solution as a measure of the amount of availablephosphate in the soil, it is suggested that the phosphate concentrationof the liquid close to the surface of the soil particles is higher thanthat in the bulk of the liquid; the root hairs of the plant maytherefore be in 8 position t o absorb phosphate from concentrationshigher than those indicated by analyses of the soil solution.It issupposed that only in extreme cases can the phosphate concentrationfall so low (lesa than 0.05 mg. per litre) that it becomes a limitingfactor in plant gromth.Investigations of a similar type have been carried out in theUnited States by F. W, Parker and J. W. Tidm0re,4~ whose resultsregarding the characteristic phosphate concentration in the soilsolution of different soils are similar to those of Wrangell. Theyalso found that the phosphate concentration of the soil solutionand of soil extracts from the untreated soil and from the soil aftertreatment with superphosphate or basic slag was increased by theaddition of lime.No marked effect was observed in the case ofsoils treated with rock phosphate, whilst after the addition ofsteamed bone flour lime caused a reduction in phosphate concentra-tion. Parker and Tidmore put forward similar views to those ofWrangell with regard to the probable existence of a higher concen-tration of phosphate in the immediate neighbourhood of the soilparticles than in the bulk of the soil solution, which they explainby the application of the Donnan theory. They differ, however,from Wrangell in regard to the limit of phosphate concentrationbelow which the plant is supposed to suffer from deficient phosphatesupply. Wrangell carried out water-culture experiments in whichthe concentration of the medium was maintained by constantcirculation. Her results appear to show that plants were able t outilise phosphate from solutions a t least as dilute as 0.1 mg.P,06per litre; she places the limit provisionally a t 0.03 mg. per litre.Parker and Tidmore, on the other hand, base their views on theresults of D. R. Hoagland and J. C. Martin,45 who found that barleyin water culture grew satisfactorily with a concentration of phosphateof 1.1 mg. per litre but suffered when the value fell to 0.7 mg. perlitre. One respect in which these views appear t o be inadequateis in regard to the marked difference in the ability of difTerent plantsto utilise insoluble phosphate. None of the hypotheses so faradvanced accounts for this difference satisfactorily; the roots ofdifferent plants would appear to possess in widely differing degrees,whether by root excretions or otherwise, the power of utilisinginsoluble phosphates.44 So4 Sci., 1926, 21, 426; B., 763.46 Ibid., 1923, 16, 367220 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Papers on this subject have also been published by M. Domonto-vitch,46 G. Ingham, 47 E. Truninger 48 and E. Ungerer.4QSupply of Bases.--In continuation of his investigations into thefactors controlling the concentration and composition of the soilsolution,60 J. S. Burdsl has published a paper dealing with theconcentration of cations in the soil solution as determined bybiological processes. Using the displacement method of obtainingthe soil solution, he has followed the rate a t which the concentrationof cations is re-established after the original soil solution has beenreplaced by water. The amount of cations present is determinedby the amount of anions formed by oxidative processes.In soilsrich in nitrates, the concentration of calcium and other cations islargely determined by the nitrate content, but when this is reducedto a low value by absorption by plants or otherwise, other anions,notably the bicarbonate anion, take the place of the nitrate. Vari-ations in the nitrate content of soils are thus no indication of vari-ations in the content of cations. F. W. Parker and W. W. Pate 52have studied the relation between the state of saturation of thesoil with calcium ions, which is correlated with its hydrogen-ionconcentration, and the '' availability " of calcium, determined byits ease of replacement by potassium acetate solution. They showthat the availability is lowest in soils of high hydrogen-ion concen-tration and vice versa, although they have not investigated therelationship between the availability so determined and the responseto liming obtained in vegetation experiments with the same soils.The injurious action of heavy applications of lime on some soilshas been investigated by E.W. Bobko, B. A. Golubev, and A. F.Tu1in.s This action cannot be ascribed to a development ofalkalinity, since both on very light soils and on heavy soils the p Evalue was raised to about the same figure, 8, but only on soils ofthe former type was the harmfuI effect observed.They ascribethis effect t o the development of excessive biological activity withthe production of excessive concentrations of calcium, bicarbonate,ammonia, nitrate and sometimes nitrite ions ; these products attain ahigher concentration in the light soil owing to its lower absorptive46 Contrib. Sci. Inst. Fertilisers, Leningrad Bull., 1924, 12, 141; A,, 1926,4' S. Afr. J . Sci., 1926, 22, 122; B., 1926, 840.45 Landw. Jahrb. Schweiz., 1925, 88, 807; B., 1926, 416.4s 2. PJant. Diing., 1926, A, 7, 362.60 Ann. Rep&, 1923, 20, 208.61 Soil Sci., 1926, 20, 269; B., 1926, 101.6 1 J . Amer. SOC. Agron., 1926, 18, 470.I* 2. Phnz. Diing., 1925, A, 6, 128; B., 1926, 1024.762.See also Ann.ReportAppZ. Chem., 1926, 10, 447BIOCHEMISTRY. 22 1capacity. The harm seems to be done mainly by the accumulationof ammonia, since the symptoms disappear as soon as the ammoniais nitrified or washed out.The relation between the supply of manganese to the plant andlime-induced chlorosis is shown by the results of E. Gilbert, F. T.McLean, and L. J. Harden.54 These workers found that chlorosiawhich occurred only on heavily-limed soils was associated with alower manganese content of the plant and could be cured by theapplication of manganese either to the soil or sprayed in solutionon the plant ; the application of iron in various forms had no effect.J. S. McHargue 55 maintains that manganese is particularly con-cerned in the synthesis of chlorophyll.Clausen5s records theprevention of " yellowing off " of oats by treatment of the soilswith manganese. T. Wallace and C. E. T. Mann,57 from an analysisof the leaves of chlorotic fruit trees, find a higher percentage ofcalcium and potassium in these leaves compared with those ofhealthy trees. These results are contrary to those recorded byother workers on lime-induced chlorosis, but are in agreement withthose obtained by H. Colin and A. Grandsire 58 in an investigationof congenital chlorosis or albinism.Attention is also directed to the investigations of W. Elliott,J. B. Orr, T. B. Wood, A. Crichton, W. Godden, and E. M. Cruik-shank 58 on the mineral content of pasture grass and its effect onherbivora.The principal bearings of this work are on the questionof animal nutrition, but the results are also of interest with regard toplant nutrition. Samples of herbage from natural pastures ofconsiderable variation in feeding quality do not differ appreciablyin their content of energy material, but marked differences in theircontent of ash constituents are found, these differences beingcorrelated with their feeding quality. The ash content of the herbagerises to a maximum during the summer and then falls. Theinfluence of mineral manures is clearly traceable in the ash contentof the herbage.The Toxic Aluminium Hypothesis of Infertility of Sour Soils.For some years past, much attention has been devoted to thepresence of soluble aluminium compounds in acid soils and the r6leof aluminium in soil infertility and toxicity.*O F.Hardy 61 hasSoil Sci., 1926, 22, 437.Deuts. Landw. Presse, 1926, 53, 326.O b Ind. Eng. Chern., 1926, 18, 172; A., 438.b7 J . Pm. Hart. Sci., 1926, 6, 115.Compt. rend., 1925, 181, 133. '' J. AgTiC. S C i . , 1926, 16, 59.See Ann. RepoTts, 1922, 10, 213; 1923, 20. 218; 1924, 21, 182; 1926,22, 205. 61 J . Ag~ic. Sci., 1926, 16, 616; B., 1024222 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.published a critical review of the present position of the subject.The following summary is largely based on that review.When acid soils are extracted with solutions of neutral salts, asin the estimation of soil acidity by some of the proposed methods,considerable quantities of aluminium as well as iron and manganeseare found in the extract.Aluminium in acid soils was regardedas the cause of their infertility, and soil acidity came to be lookedupon as a merely secondary consequence of the known susceptibilityof aluminium salts to hydrolysis. Subsequent work showed thataluminium could be detected by ionic reactions in soil extractsonly when their hydrogen-ion concentration was higher than thatcorresponding to pE 4.5 (Rice). It was therefore assumed that inless acid soils and extracts the soluble aluminium occurred as un-ionised hydrated alumina hydrosol. The demonstration of theinability of the aluminium in acid soils and extracts to pass throughsemipermeable membranes was held to support this view. It wasthen maintained that, so far from soil acidity being a consequenceof the hydrolysis of aluminium salts, the reverse was the case;ionised aluminium was supposed to occur only when the acidity ofthe soil or extract was sufficient to convert the un-ionised hydroxideinto an ionised salt (Denison).The recent work of Magistad hasadded considerably to our understanding of the position. Hestudied (a) the influence of hydrogen-ion concentration on thesolubility of aluminium originally present as sulphate, ( 6 ) the amountof aluminium in soil solutions displaced from soils of variousreactions, and (c) the state of occurrence of aluminium in soilsolutions. He showed that, between the pH limits of 4-7 and about8, only very small amounts of aluminium existed in solution, eitherin simple aqueous solutions derived from aluminium sulphate or indisplaced soil solutions, and that these small amounts existed incolloidal dispersion and not in true molecular or ionic solution.He therefore concluded that aluminium should not exert toxiceffects on plants unless the reaction of the medium lay outside therange of pa 4.7-86.This was supported by vegetation experimentsin sand a t various pR values in presence and in absence of aluminium.Although certain species of plant showed some sensitiveness toaluminium toxicity, this was never strong a t reactions less acidthan pH 5, and most plants showed much more sensitiveness tohydrogen ion than to aluminium.Hardy goes on to discuss the position in regard to recent workon the physico-chemical properties of hydrated alumina, withspecial reference t o its isoelectric point and the formation of co-ordinakd complex anions and organo-compounds. Soluble alu-minium in both these forms, as well as in the form of simpIe ionBIOUHEMISTRY.223or more complex colloidal electrolytes, may possibly penetrate plantroot cells and be translocated within the plant, but it appears t oexert true toxic effects only when existing as simple ions or themore soluble colloidal electrolytes ; absorption of aluminium inother, non-toxic, forms may result in the accumulation ofaluminium in certain regions of the plant, with consequent dis-turbance of metabolic processes and predisposition to certaindiseases. The use of dialysis experiments, which has contributedto the above views, is questionable, since dialysis disturbs theequilibrium conditions in hydrated colloidal systems and sincedialyser membranes do not simulate plant cell membranes.HOW-ever, there is considerable evidence derived by other means t osupport the conclusion that within the reaction range a t whichtoxic aluminium compounds cannot exist in soils-a range whichincludes that of the reactions of most soils-hydrogen ions mayexert a controlling influence on plant growth. It is, however,inadmissible to apply in this connexion a strict reaction range t oall soils; moreover, the variations in the sensitiveness of differentspecies of plants must not be disregarded.The recently published work of J. Line 62 is in full accord with themain conclusions outlined above.He could fhd only very smallamounts of soluble aluminium in acid soils, and could not correlatethese amounts with crop yields from these soils. In addition t othe direct toxic effect of hydrogen ion above certain concentrations,the precipitation of phosphates, with consequent phosphate starv-ation of the plant, may be responsible for the harmful effects wronglyattributed to the direct effect of aluminium in solution cultures(compare Gile, Magistad).The Penetration of Xalts into Plants, and their Inorganic NutritiveRequirements.In addition t o the large numbers of papers on the toxic or stimu-lating action of various inorganic salts on plant growth and onthe penetration of various ions into plant-tissues, special mentionmust be made of the work of D.R. Hoagland and his co-workersand of W. F. Gericke. The former, in collaboration with P. L.Hibbard and A. R. has continued his investigations on theinfluence of light, temperature, and other conditions on the abilityof the cells of Nitella to concentrate halogens in the cell sap. Ithas been shown that this fresh-water alga can absorb bromine fromvery dilute solutions containing bromide, without damage to thecell8, until the concentration of bromine inside the cell may beJ. Agric. Sci., 1926,16, 335; B., 891.e3 J. Gsn. Physiol., 1926, 10, 121224nearly sixty times that in the surrounding medium. This absorptiondoes not occur in the dark, light being essential to the process, thetemperature coefficient of which is comparable more with that of achemical reaction than with that of a diffusion process.The processmay take a month or more to reach equilibrium. Chlorine may belost from the cell as a result of the accumulation of bromine, orvice vema, but both these elements may accumulate together toconcentrations much higher than those in the surrounding liquid.Osterhout 64 has recently advanced the view, from work on theabsorption of carbon dioxide or hydrogen sulphide by Valmia, thatthe penetration of living protoplasm is confined to undissociatedmolecules, ions being unable to enter. Whilst this view is sup-ported by the work of M. Irwin 65 on the absorption of brilliant-cresyl-blue by Nitella, M. M.Brooks 66 could find no evidence for itfrom her results with Valonia and solutions of arsenic or arseniousacids. Hoagland, Hibbard, and Davis prefer to interpret theirresults as involving the absorption of ions, in view of the very dilutesolutions employed and from other considerations. They directattention to a number of points of dissimilarity between Osterhout'sresults and their own which throw doubt on the applicability of theformer's views to the processes they have studied.W. F. Geri~ke,~' who has already published preliminary accountsof his experiments on the nutrient requirements of wheat a t differentstages of growth, has now published fuller details. It is knownthat the greater part of the absorption of inorganic elements bycereals occurs in the earlier part of their growth, the later stagesbeing most marked by elaboration and translocation of organicmaterials inside the plant.Gericke has attempted to ascertain towhat extent the plant could therefore be deprived of certain nutritiveelements in the later stages of its growth without detriment. Work-ing with water cultures, he made the rather surprising discoverythat when plants were grown for the first few weeks in a completenutrient solution and then transferred, when they had made only asmall fraction of their total growth, to a solution deprived of eitherpotassium, magnesium, sulphur, or phosphorus, they producedmarkedly more grain and straw than did plants grown to maturityin the complete nutrient solution. When the plants were deprivedof phosphorus after 4 weeks, they produced nearly 50% more strawand more than 2 i times as much grain as when they were supplied64 W.J. V. Osterhout and M. J. Dorcas, J. Qen. PhyaioZ., 1926--1926,9,255;a5 Ibid., 1926, 9, 661; A., 647.8 6 Amer. J . Physiol., 1926, 70, 116; A., 645.67 Bot. Uaz., 1925, 80, 410.ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.W. J. V. Osterhout, &d., 1925-1926, 8, 131BIOCHEMISTRY. 225with this element throughout their growth. Calcium, iron, andnitrogen, however, are needed apparently for most of the period ofgrowth; deprivation of the plants of these elements a t any periodof the growth up t o ten weeks from the commencement caused adiminished yield of grain and straw. No explanation has yet beenadvanced for these interesting results, which would, however,appear to have important bearings on the relation of soil conditionsto crop production.Synthesis and Metabolism of Carbon Compounds in Plants.The occurrence of aldehydes in plants and their r81e in metabolicprocesses are attracting much attention, but interest has shiftedfrom formaldehyde to acetaldehyde.The occurrence of the formeras a step in the photosynthetic process now seems t o be definitelyestablished. G. Klein and 0. Werner 68 have isolated it from variousplants by means of " dimedon " (dimethyldihydroresorcinol). Itwas obtained only from tissue containing chlorophyll, which wasexposed to light. Narcosis with phenylurethane or the presence ofhydrogen cyanide resulted in its absence.T. Sabalitschka andH. Weidlir~g,~~ in continuation of their work on formaldehydeassimilation by plants, have shown that the aquatic plant Elodeacamdensis can polymerise formaldehyde to higher carbohydratesirrespective of whether t,he plant is illuminated or not. Theoptimum concentration of formaldehyde in the liquid is 0.024%.The same authors 70 have obtained similar results with acetaldehyde,the optimal concentration in this case being 0.032%. G. Kleinand K. Pirschle,71 also using dimedon, have demonstrated thepresence of acetaldehyde in actively respiring organs of plants andin roots and leaves. K. Pirschle 72 has found relatively largequantities in germinating seeds rich in fat. He considers that it isprobably formed during the utilisation of dextrose from the fatof the seeds, but it may also be an intermediate stage in the con-version of fat into sugar.C. Neuberg and A. G~ttschalk,~~ andalso J. BodnL, C. Szepessy, and J. Ferencz~,~' have found alcoholaa well as acetaldehyde in germinating seeds, in relative amountssupporting Neuberg's view that acetaldehyde is an intermediateproduct in alcoholic fermentation of sugar.P. Haas and T. G. Hill 75 have continued their study of the water-** Biochem. Z., 1926, 168, 361; A., 439.Ibid., 1926, 172, 45; A., 871. 70 Ibid., 1926, 176, 210; A., 1182.Ibid., 1926, 168, 340; A., 439. 72 Ibid., 1926, 169, 482; A,, 547.73 Ibid., 1925, 160, 256; A,, 1926, 98. '' Ibid., 1926, 165, 16; A,, 1926, 438. '' Ann. Bot., 1925, 39, 861; 1926, 40, 709; A,, 1926, 99, 1066.REP.-VOL.XXIII. 226 ANNUM, RBPORTS ON THE PROGRESS OF CHEMISTBY.soluble chromogen--“ hermidin ”-isolated from Mercurialis. Theoxidation of this chromogen to the blue pigment “ cyanohermidin,”and thence to the yellow “ chrysohermidin ” is not due to enzymeaction. Equal amounts of oxygen are required for the two stages.The process is reversible, the yellow pigment being reduced to theblue and thence to the chromogen by the aluminium-mercurycouple, whilst hermidin itself can effect the first stage of the reduc-tion. It is suggested that hermidin plays some part in the oxidationmechanism of the plant. R. K. Cannan 76 has measured the electrodepotentials of the system hermidin-cyanohermidin.Nitrogenous Metabolism and Constituents of Plants.The relation between calcium supply and protein content ofleguminous plants, t o which reference has been made in recentReports, has been further studied by J.M. Ginsburg and J. W.S h i ~ e . ~ ’ Working with soy-beans in soil and in water-cultures, theyfound that variations in the supply of calcium in the form of nitrateor chloride had no significant effect on nitrogen uptake, but thepresence of calcium carbonate definitely increased the nitrogencontent of the plant. Since, however, this was always to be corre-lated with lower hydrogen-ion concentration in the medium, it ispossible that the latter factor is the determining one and that theeffect of calcium carbonate is due to its influence in reducing thehydrogen-ion concentration.Moreover, the view that calciumsupply caused increased protein synthesis is not supported by theirresults, since the increased nitrogen content of plants grown in thepresence of calcium carbonate was wholly due to an increase in thenon-protein nitrogen.The complete inadequacy of our knowledge of the compositionof the cell sap of plants is the chief hindrance to a better under-standing of the processes involved in protein synthesis and nitrogen-ous metabolism. The work of H. B. Vickery 78 and his associatesin Osborne’s laboratory a t New Haven, to which brief reference wasmade last year, marks the beginning of an attempt to improve ourknowledge in this field. The most widely occurring soluble nitrogencompound in plants appears to be asparagine, which is often regardedas the chief form in which nitrogen compounds are translocated.79Vickery’s results show that this substance is the most important76 Biochem.J., 1926, 20, 927; A., 1183.7 6 J . Bid. Oh-%.. 1926, 65, 657; A,, 1926, 99.Ann. Report, 1924, 21, 190.Soil. Sci., 1926, 22, 175; B., 969.See also Ann. Report,See also A. Tokarewa, 2. physioL Chem.,1925, 22, 212.1926, 158, 28; A,, 1183BTOUHEMWI?RY. 227simple constituent among the soluble nitrogen compounds inlucerne. A number of other amino-acids have been isolated fromthe hydrolysis products of the soluble nitrogen compounds, includingserine and alanine, which have not hitherto been recorded as con-stituents of plant juice.Vickery 80 has also commenced a study ofthe simpler nitrogenous constituents of yeast ; the basic substancesnot precipitated by Neuberg’s reagent consist largely of cholineand nicotinic wid. Yeast appears to be incapable of methylatingnicotinic acid, and bases of the betaine type, if present, can occurin only very small proportions. R. Fosse 81 claims to have demon-strated the presence of nllantoic acid in extracts of Pheolus andsuggests that the urea produced on heating extracts of some plantsis formed by hydrolysis of allantoic acid. T. Sabalitschka andC. Jungermann 82 have followed the variations in alkaloid contentof Stryehnos nux vomica during germination and early growth.Initially decomposition of the alkaloid appears to occur, but latera resynthesis takes place, the nitrogen being apparently derivedfrom the reserve protein of the seed.0.Loew claims to show that the protein present in the cells ofgrowing plants exists in a very labile form differing in structurefrom the stable modification which can be isolated from the plant.A. C. Chibnall and C. E. Grover,8* in commencing a study of leafcell cytoplasm, have investigated the soluble proteins which passreadily into solution when the leaves of plants are extracted withwater. They resemble glutelins in their properties and theirisoelectric point lies between pH 4.0 and 5.0, in which range theirsolubility is a t a minimum. In all cases, the leaf cell-sap had a pxhigher than the above range, indicating that the protein exists inthe cells in the form of anions.Soluble protein could not be obtainedfrom the leaves of plants of which the leaf cell-sap was not alkalinewith respect to the isoelectric range. F. A. Csonka, J. C. Murphy,and D. B. Jones 85 have examined a number of vegetable proteinsby a modification of Sorensen’s method. The more soluble proteinghad lower isoelectric points and required more ammonium sulphatefor salting-out. The isoelectric points of globulins from differentsources were very close together ; the same is true of the albuminsand prolamins.J . Biol. Chem., 1926, 68, 585.Compt. rend., 1926, 182, 869; A., 548.Biochem. Z., 1926, 167, 479; A,, 440.Chem.-Ztg., 1926, 50,429; A,, 871; Ber., 1925, 56, [B], 2805; A., 1926,Biochem. J . , 1926, 20, 108; A., 441.See also A. C . Chibnall, J . Amer.439.Chem. Soc., 1926, 48, 728.s5 Ibid., p. 763228 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.T. Tadokoro, Y. Nakamura, and S. Watanabe 86 have made acomparison of the properties of oryzanin preparations from commonrice and from glutinous rice. The protein from common rice appearsto be more complex than the other, as shown by hydrolysis and alsoby its greater resistance to decomposition by pancreatin. W. F.Hoffman 87 has isolated from rice a protein, soluble in 70% alcohol,which approximates in composition to the alcohol-soluble proteinsof maize. B. Takahashi and T. Itagaki88 have isolated twoglobulins from the adzuki bean (Adzukia subtrilobata). M. C.McKee and A. H. Smith a9 have isolated two proteins from theedible portion of the cauliflower.Carbohydrate and Xtructural Constituents of Plant Tissues.From X-ray analysis of plant fibres, 0.L. Sponsler 90 concludesthat the wall of the fibre has a lattice structure in which the unitcell has the dimensions 8-10 x 5.40 x 10.30 &, and contains twoC,H,,O, groups. These cells are supposed to be arranged in unitsof four in the crystallographic unit. The C,H,,O, groups appearto be of two types which are arranged alternately in chains. Thestructure of the fibre as a whole is thought to be that of a series ofconcentric layers of unit cells.H. Colin and A. de Cugnac 91 describe the isolation of gramininand tricitin, lsvulosans from Arrhenatherzcm bulbosum and Triticumrepens, respectively.They have no reducing action and on hydrolysisyield only laemlose. Enzymes capable of hydrolysing them arefound in the plants from which they were prepared.W. H. Dore 92 has published a useful review of the present stateof pectin chemistry, whilst a monograph on the same subject hasbeen published by R. Sucharipa.93Pectic substances can be divided into three groups, protopectin,pectin, and pectic acid. Protopectin, formerly called pectose, occursin unripe fruits and other parts of plants and is insoluble, Theother forms of pectin are derived from it. Pectin itself, whichoccurs naturally in the juice of ripe fruits or may be obtained from88 J . C022. Agric. Hokkaido Imp. Univ., 1925, 14, 129; A., 1926, 1066.8 7 J . Biol.Chem., 1925, 88, 501; A., 1926, 441.88 J . Biochem. (Japan), 1925, 5, 311; A., 1926, 1066.89 J . Biol. Chem., 1926, 70, 273; A., 1183.90 J . Uen. Physiol., 1926, 9, 677; A., 760.9 1 Bull. SOC. Chim. biol., 1926, 8, 621; A., 1066.g8 J . Chem. Education, 1926, 3, 505.98 " Die Pektinstoffe " (Braunechweig), Serger and Hempel, 1926. 188 pp.See also Ann. Report, 1925, 22, 213; F. W. Nonis, Biochem. J . , 1926, 20,993; A., 1183; W. H. Dore, J . Amer. Chem. SOC., 1926, 48, 232; B., 171;M. A. Griggs and R. Johnstin, Ind. Eng. Chem., 1926,18, 623; B., 643; W.Honneyman, J. Text. InBt., 1925, 16, T., 370; B., 1926, 187BIOCHEMISTRY. 229protopectin by mild hydrolysis, is soluble. Pectic acid is a productof further hydrolysis of pectin; it occurs in over-ripe fruits.Von Fellenberg showed in 1917 that pectin is the methyl ester ofpectic acid and in the same year Ehrlich stated that the carboxylgroups of pectic acid were present in galacturonic acid units, Ehrlichalso isolated, by hydrolysis of pectin, a tetragalacturonic acid inwhich four galacturonic acid groups are condensed with the elimin-ation of three molecules of water.I n the production of this sub-stance from pectin, galactose as well as methyl alcohol is split off.Tutin’s view that pectin is the dimethyl isopropenyl ester of pecticacid, based upon his identification of acetone among the productsof saponification of pectin has not been accepted by later workers.Schryver and Haines, from the concordant analyses of pectic acidsprepared from four different sources, derived the formula C17H24016.Subsequently Carre and Haines concluded that pectic acid is dibasic,having found that the product isolated by Schryver and Haineswas a calcium salt with the formula C,,H,,016Ca. Quite recently,Nanji, Paton, and Ling have isolated a substance which they regardas the basic unit of pectin and which in their view contains a hexa-ring in which four contiguous galacturonic acid units are combinedwith arabinose and galactose.A unit of this constitution has theformula CsH6,0,, ; it would appear to be identical with Schryverand Haines’s pectic acid, with which it closely agrees in elementaryanalysis. The known fission products of pectic acid can all beaccounted for on this basis. Pectin is the corresponding methylester.The partly methoxylated intermediate products describedby Fellenberg and Sucharipa can be accounted for by assumingthat only part of the carboxyl groups is methylated. Norris andSchryver, who have accepted the above hexa-ring structure, con-clude that in the original pactic substance of the plant one carboxylgroup is free and the other three groups are methylated. Proto-pectin may be regarded as tho result of the condensation of thisfourth carboxyl group with other radicals.Pectin solutions are probably not true solutions but sols ; althoughpossibly in some cases the gelatinous precipitates obtained by theaddition of salts may be metallic pectates, this method of coagulationappears to be chiefly due to the normal coagulation of a sol by anelectrolyte.The action of a small amount of acid on a solutioncontaining pectin and sucrose gives a stable gel, constituting thematerial of the well-known fruit jellies. With regard to the r81e ofpectic substances in plants, these apparently occur mainly asincrustive substances. The middle lamella which cements togetheradjoining cell-walls consists largely of protopectin. The earlierview that protopectin is a calcium salt of pectin has been questione230 ANNUAL REPORTS ON THE PROGRESS OB CHEMTSTRY.by von Fellenberg and recently Sucharipa has put forward evidenceto show that it is a combination between pectin and celldose, thesetwo substances being liberated in uniform proportions uponhydrolysis of protopectin.The marked changes in texture which accompany the ripeningand over-ripening of fruit may be regarded as due to (a) the dis-ruption of the union between cellulose and pectin, to which thefirmness of unripe fruit is due, ( b ) the saponification of pectin withresultant complete disintegration of the tissue structure in theover-ripe or rotten fruit.From the work of Nanji, Paton, and Ling, the synthesis of pectinin the plant may be supposed to occur by the condensation ofgalactose to'a hexa-galactan, which is thenoxidised andmethoxylated.Von Fellenberg regards pectin as the precursor of lignin ; in growingtwigs, increase in lignin is accompanied by decrease in pectin, whilstthe presence of methoxyl groups in both substances is in favour oftheir being related.W. Fuchs 94 also regards lignin as a productderived from pectin by loss of oxygen and water.M. M. Mehtag5 maintains that lignin can be quantitativelyliberated from its union with cellulose in wood by heating with 4%sodium hydroxide solution for 1 hour a t 10 atmospheres. It canbe isolated and estimated by precipitation of the resulting liquidwith acid and extraction of the product with alcohol. The sub-stance so obtained is brown and acidic and melts a t 170"; it issoluble in dilute alkalis and in dilute alcohol. Earlier preparations(e.g., by Wilhtatter's method) are regarded as impure. The ligninis thought to be combined as a glucoside in lignocellulose. C. Dor6eand E. C. Barton-Wright find that the lignocellulose present inthe stone cells of the pear resembles that present in forest woodsrather than annual lignocellulose such as that of jute.The stone-cell material contains 80% of lignocelluloso, of which three-quartersare cellulose and one-quarter is lignin. About three-quarters of thiscellulose appears to be true a-cellulose, the remainder consistingof p-cellulose, which yields 74% of its weight of furfural. Theremaining 20% of the stone-cell material consists largely of analkali-soluble furfuroid which yields, besides furfural, acids of thegalacturonic type. This result is of interest in relation to theabove-mentioned suggestion of von Fellenberg and of Fuchs regard-ing the origin of lignin from pectin.9704 Brennstoff-Chem., 1926, 7, 302.98 Ibid., 1926, 20, 502; A,, 872.9' For other papers on lignin, aee A.Friedrich and J. Diwald, MonatBh.,1925, 46, 31; B,, 1926, 151; H. Urban, Cellulosechem., 1826, 7, 73; B., 631;K. Freudenberg and H. Hem, BrennatofiChem., 1926, 7, 351; A. R. Bowenend A. W. Naah, Fuel, 1926, 5, 138; B., 474.p 6 Biochem. J., 1925, 19, 958BIOCHEMISTRY. 231The hemicelluloses of beechwood have been isolated by M. H.O'Dwyer.98 One of them yields xylose and glycuronic acid onhydrolysis, whilst the other resembles pectin in giving arabinose,galactose and galacturonic acid.Plant Phosphatides.P. A. Levene and I. P. Rolf, in continuation of their work onthis subjectJg9 have further examined the lecithin previouslyisolated from the soy-bean.1 They have also isolated a fractioninsoluble in glacial acetic acid, resembling the cuorin described byErlandsen in 1907, yielding on hydrolysis palmitic, stearic, linoleicand linolenic acids, aminoethanol, and barium glycerophosphate.V. Grafe and H.Magistris have further studied the water-solublephosphatides of plants. These appear to occur in the dialysate fromNorwegian peas in combination with pigment and carbohydrategroups. By extraction of the peas with warm alcohol, the phos-phatide could be obtained free from these substances. Thephosphatide complex present in water dialysates of plant foodstuffsis thought by these authors to possess vitamin activity.Frost Resistance of Plants.Earlier work carried out by R. Newton has shown that on theapproach of winter there is an accumulation of hydrophilic colloidsand of sugars in wheat plants.The hydrophilic colloids increasethe water-retaining powers of the tissues and the sugars tend tostabilise the proteins against frost denaturation. Newton has nowpublished, in conjunction with W. R. Brown: the results of a morecomprehensive study of this subject, in which the changes occurringin winter wheat plants, of varying degrees of hardiness, have beenfollowed during the autumn and winter months. By analysing thepress juice as well as the entire tissues, a t intervals throughout theinvestigation, it was possible to study the distribution of the con-stituents between the cell contents and the supporting framework.The most important adaptation to the onset of wintry conditionsis the reduction of moisture content, which takes place to thegreatest extent with the hardiest varieties, tbe resulting concentrationincreasing the resistance to freezing.The bulk of the colloids inthe cell contents consisted of proteins; 90% of the whole proteinof the plant was contained in the fluids. Pentosans were found tobe restricted almost wholly to the structural parts of the plant.9 8 Biochem. J., 1926, 20, 656; A., 983.1 J. Biol. Chem., 1926, 68, 285; A., 982.2 Biochern. Z., 1926, 176, 266; 177, 16; A., 1279, 1280.8 J . Agric. Sci., 1926, 16, 522; B., 991.w Ann. Report, 1925, 22, 213232 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,Concentration of sugar increased most in the hardiest varieties, thusgiving them the greatest resistance to frost denaturation of proteins.There was no evidence that lipoids play any important part in thephysiology of frost resistance of wheat.The commonly held view,first advanced by MacDougal,4 that pentosans were of the greatestimportance in frost resistance would not appear to be tenable inthe case of wheat. Moreover, the work of J. Doyle and Miss P.Clinch indicates that for conifers also there is no apparent con-nexion between cold resistance and pentosan content of the leaves.Enzymes.Space does not permit of a general review of the very large amountof work that is being published on this subject. However, thepublication by R. Willstatter of two summaries of the resultsobtained by him and his collaborators provides a convenientopportunity to take stock of the position in that section of thesubject that he has studied during recent years : the methode ofisolation and characterisation of enzymes.So many lengthy papershave issued from the Munich laboratory that the task of masteringtheir contents is formidable, and the opportunity of learningWillstatter’s own opinion regarding the most important advancesin the subject is a weIcome one.Touching the specificity of enzymes, it is pointed out that,although different proteoclastic enzymes may attack the samesubstrate, they do so a t different atomic groupings. An interestingfurther development of this is the result recently obtained byR. Kuhn, according to which there are two invertases, whichhydrolyse sucrose by attaching themselves to the glucose and laevuloseradicals respectively.Willstiitter’s method for the isolation of yeast invertase consistsin the rapid killing of fresh yeast with ethyl acetate and removalof the cell sap poor in enzyme which separates during the first hour.By autolysis of the residue a t neutral reaction is obtained an invertasesolution contaminated with only one-tenth or one-twentieth of theyeast material.If the yeast is first allowed to ferment a very weaksolution of sucrose, maltose, or glucose, its invertase content can beincreased 15-20 times (but not its content of other enzymes),The invertase solution obtained as above from such an inver-tase-enriched yeast is eight times purer than the best invertinpreparations.The fermentation of a biose by yeast does not follow the course4 Carnegie Inst.Wash., Publn. No. 297, 1920.6 Ber., 1926, 59, [B], 1; A., 321; Naturwiss., 1926, 14, 937.Sci. Proc. Roy. Dublin. SOC., 1926, 18, 219, 265; A,, 1280BIOCHEMISTRY. 233supposed by Fisoher and Lindner, involving the preliminary hydro-lysis to monoses before alcoholic fermentation occurs. Maltosecan be fermented by maltase-free yeasts, and yeasts rich in maltasecan ferment maltose under such conditions ( p , 4-5) that maltosefission by maltase is impossible.The quantitative estimation of enzymes is possible if the influenceof time, temperature, concentration of substrate, acidity, etc.,is studied and these conditions are accurately defined. Specialaccount must be taken of variations in specificity.Thus pancreatiolipase is a powerful fat-hydrolysing agent, but without much actionon other esters ; for liver lipase the converse is true. One mg. ofdried pancreas will hydrolyse as much methyl butyrate as 0.4 mg.of liver, but in saponifying olive oil it is as active as 10 g. of liver.It has not yet been possible to standardise conditions sufficientlyin the case of peroxydase to obtain constant results.I n the purification of enzymes great difficulties are met with inthe removal of contaminating substances. Chemical methodscannot be used, since the enzyme may be altered. Willstatter hasutilised with great success the method of absorption on dry kaolinand other substances. Each step of the process is quantitativelyfollowed.The amount of enzyme absorbed by 1 g. of the absorbentis called the absorption value (A.W.). By suitably altering theconditions it was possible to increase the A.W. of alumina forinvertase from 0.15 to more than 200, a t which value 1 g. of aluminaheld the invertase from 12--14 kg. of fresh yeast, and the weight ofthe ‘‘ absorbate ” was 2.;3. g. The absorbed material was not a homo-geneous substance, but an enzyme-containing complex. Gels ofaluminium hydroxide exist in three forms, K, p, and y. The y-formis the most stable, and the strongest absorbent of saccharase. Whenseveral enzymes occur together (e.g., pancreas), they can often beseparated through selective absorption on different absorbents.The freeing of an enzyme from its associated impurities has oftena marked effect on its specificity.Thus purified trypsin acts onlyon peptone, histone, and certain prolamines ; trypsin and entero-kinase act on fibrin, casein, and gelatin, whilst erepsin can act onnone of these, but only on simple peptides unattackable by activatedtrypsin.Almost all the properties usually ascribed to enzymes belongactually t o the accompanying impurities; even the optimum pHis not a function of the enzyme itself, but depends also on thesubstrate. Thus carica and pineapple protease hydrolyses fibrinbest a t pa 7.2, but gelatin and peptone a t pH 5.0. In these cases,the optimum falls within the isoelectrio ranges of the substrates,but in other cases, as in that of human and canine gastric lipase,a 234the optimum pErises with the purity of the enzyme.Unpurifiedpreparations of gastric lipase act best a t pH 5-6, but after absorptionon kaolin or alumina the best action is a t pH 8, which is the value forpancreatic lipase. This phenomenon is explained on the assumptionthat in the purification there is removed a substance that hindersaction in alkaline media, and aIso another that favours action inacid media.The use of homogeneous enzyme preparations may prove of greatvalue in the study of the constitution of the proteins, as it allows ofpartial and specific decompositions whereby definite groupings canbe identified.The “ molecule ” of an enzyme appears to consist of a colloidalcarrier and a purely chemically active group.The specificityof the enzyme is vested wholly in this active group, which canapparently be transferred from one colloidal carrier to another.It has not yet been possible to separate the enzyme molecule properfrom the colloidal carrier without loss of activity.ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.B i o c h e m i s t r y of A n i m a l s .Internal Secretions.Thyroxine.-When last year the Reporter gave an account ofHarington’s opening researches on the nature of the active principleof the thyroid gland, he had little idea that within twelve monthsthe constitution of that compound would have been revealed and itssynthesis effected by one of the most perfectly planned andbrilliantly executed investigations that have ever reflected crediton the British School of Biochemistry.It will be recalled 1 that Harington’s synthesis of 3’ : 4’ : B’-tri-iodophenylpyrrolidonecarboxylic acid was carried out because theempirical formula is practically the same as that proposed forthyroxine by its discoverer Kendall, and because the properties ofthe active substance might be more satisfactorily accounted for bythe structure of a phenylglutamic acid than by the indole structureput forward by Kendall.The absence of any physiological activityin the product of Harington’s synthesis led him to direct a mainattack on thyroxine itself.In the first place, he succeeded in so modifying Kendall’s methodof isolating thyroxine from the thyroid gland that he obtained yieldsas high as 0027% ; that is, approximately twenty-five times aBlarge as the yields obtained by the American investigator.3 Nextlie established t,he empirical formula of the purified substance as1 Ann.Report, 1925, 22, 222. a Biochem. J., 1926, 20, 293BIOCHEMTRTRY. 235being C15Hlr0,NI,, instead of C1,Hl,O3NI3 derived from Kendall'sanalyses. The third step was to determine the structure of themolecule, and the evidence accumulating during this part of thestudy led Harington to believe that the iodine-free substance,deiodothyroxin, was the p-hydroxyphenyl ether of tyrosine (11).Proof of the correctness of this belief was soon provided by thesynthesis of this compound and the demonstration of its identitywith the product formed by removing the iodine from naturalthyroxine.The synthesis was effected as follows :M e O e r + H O O -+ M e O o - 0 - 01AlternativeIy the aldehyde (I) could bepiperazine :(11.1condensed with diketo-M e O o O o + HHr A 2 0Z H O ~ - O ~ , ~ C H ( N H , ) ~ C O , H +- OC\ ,kHMe O o - O - & HThe final stage of this brilliant achievement has just been reported,namely, the insertion of the four iodine atoms and the synthesis ofthyroxine itself.4As Harington pointed out in his earlier paper, it seemed probablethat the iodine atoms would occupy the 3 : 5 : 3' : 5'-positions, iffor no other reason than the known existence of 3 : 8-di-iodo.tyrosine in natural products. This surmise has proved to be correct.Quinol monomethyl ether was condensed with 3 : 4 : 5-tri-iodo.* Biochern.J., 1926, 20, 300.Report of the meeting of the Biochemical Society (Dec. Sth), J. Soo. Chem.Znd., 1926, 45, 931236 ANNUAL REPORTS ON THE PROCRESS OF CHEMISTRY,nitrobenzene to give 2 : 6-di-iodo-4-nitro-4’-methoxydiphenylether (III). This was converted through the amine (IV) and thenitrile (V) into the aldehyde (VI), which condensed with hippuricI Iacid to give the corresponding azlactone (VII). The benzamido-cinnamic ester obtained from this, on treatment with hydriodicacid and red phosphorus, gave p-[3 : 5-di-iodo-4-(4‘-hydroxy-phenoxy)phenyl]-a-aminopropionic acid (VIII). Finally, on treat-ment with iodine in ammoniaoal solution, (VIII) was convertedinto the tetra-iodo-compound (IX), p-[3 : 5-di-iodo-4-(3’ : 5’-di-iodo-4’-hydroxyphenoxy)phenyJ]-cc-aminopropionic acid, a sub-stance indistinguishable chemically and physiologically from naturalthyroxine.The intravenous administration of 14 mg.of the synthetic pro-duct to two myxmdematous patients in three doses over a period of6 days caused a rise in the basal metabolic rate from - 45% to + 3% in one case, and from - 32% to - 6% in the other; in bothcases, the expected increases in pulse rate and loss of weight werealso observed.West has reported that the related compounds 3 : 5-di-iodotyrosyl-3’ : 5‘-di-iodotyrosine and the diketopiperazine corre-sponding to 3 : 5-di-iodotyrosine are without effect on the basalmetabolism.Proc. SOC. Exp. Biol. Med., 1926, 23, 629BIOCHEMISTRY. 237Gstrin.-Steady advances are reported in the study of ovariansecretion.Parkes 6 has pointed out that the ordinary cyclicoccurrence of estrus in the adult female mouse is maintained in theabsence of follicles and corpora lutm, and that there is char evidenceagainst the view that the responsible hormone, termed by himcestrin, is elaborated by the follicle.It is also apparent from his researches that cestrin is being con-stantly produced by the ovary, so that it is necessary to supposethat during pregnancy and lactation, when cestrus does notnormally occur, there is an inhibitory action, believed to be exertedthrough the persistent corpus luteum, which prevents the attain-ment of the threshold concentration of estrin necessary for theproduction of cestrus.Definite evidence of this balanced hormone action is provided bylater work in which i t is shown that the injection of cestrin duringthe early stages of pregnancy invariably causes the rapid reappear-ance of cestrus and the termination of pregnancy; the same effectsare produced in the later stages if a larger dose is administered.The chemical nature of cestrin has been further examined byRalls, Jordan, and Doisy,s who obtained from liquor folliculi a fattymaterial free from cholesterol, of which 0.034-09 mg.is 1 ratunit. By fractionation with light petroleum, the unit may bereduced to 0.015 mg. The active principle can be distilled in a highvacuum, but always suffers considerable loss in potency withoutany gain in purity.The activity does not withstand acylation or bromination but isunaffected by hydrogenation or hydrolysis.Tentatively, it issuggested that the hormone molecule contains a hydroxyl groupand a double bond. Hartmann and Isler 9 confirm the observationthat estrin may be distilled in a high vacuum and state that theactive fraction consists of esters of higher unsaturated acids. Onsaponification, the activity is transferred to a material whichdistils a t 145"/0.02 mm. The preparation of a physiologicallyactive, water-soluble substance of somewhat different propertiesis described by Laqueur, Hart, de Jongh, and Wijsenbeek.10 I t srelation to the product known as cestrin is not clear, but theseauthorities regard their preparation, which they term menformon,as a purer form of the active principle.Secretin.-In a preliminary communication J.Mellanby 11 claims8 PTOC. Roy. Soc., 1926, [B], 100, 151.7 Parkes and Bellerby, J . Phyaiol., 1926, 62, 145. * J . Bid. Chem., 1926, 69, 3 5 7 ; A., 1064.Biochem. Z., 1926, 175, 46; A., 1064.lo Proc. R. Akad. Wetemsch. Amsterdam, 1928, 28, 890; A., 1926, 546.l1 J . Physbl., 1926, 01, XXXVII; A., 1064238 ANNUAL REPORTS ON THE PROGRESS OF UHEMISTRY.to have isolated secretin. His method for its preparation inspireslittle confidence that anything approaching a pure compound hasbeen obtained, but his products appear to be highly active. OnsIender evidence, it is suggested that secretin is a polypeptide.Insulin.-No appreciable abatement of the flood of papers dealingwith insulin from one aspect or another is yet apparent, and thetask of selecting those most suitable for review is still a formidableone.With regard to the chemical nature of the active principle of theinternal secretion of the pancreas, Punk l2 claims to have isolatedinsulin by way of its compound with flavianio acid and suggestsalternative formulse C,,Hl,,02~1,S and C,4H,14024N2,S, eitherof which might represent a polypeptide with about 15 conbtituentamino-acids.Abel l3 has prepared a crystalline compound, ofdefinite melting point (233") , having powerful insulin actions andgiving several colour reactions characteristic of protein derivatives.On the other hand, Allen and Murlin l4 claim to have prepared ahighly active product which gives none of these colour reactionsand therefore could not be of the nature of a peptide.As yet, theevidence in support of these various claims seems confusing.Passing reference must be made to the rather startling experi-mental results recorded by Bertrand and Mbhebceuf,15 althoughtheir significance is far from clear. Starting from the discoverythat the pancreas of all the species investigated contained, in com-parison with other organs, relatively large quantities of nickel andcobalt, and that preparations of insulin itself contain these elements,an investigation was made into the relation between the physio-logical activity of the pancreas and the presence of the metals. In-jection of small doses of nickel or cobalt salts intensified the insulineffect in rabbits and dogs, and it is now claimed that injection ororal administration in human cases of diabetes has sometimes beenfollowed by an alleviation of symptoms.The much discussed question of the fatre of the sugar which dis-appears from the blood under the action of insulin seems a t last tohave been answered in a satisfactory manner. The theory thatinsulin promotes the esterification of blood-sugar with phosphoricacid is not supported by an extension of the work of Burn and Dalecarried out by Best, Hoet, and Marks.1' From this investigation,carefully controlled a t all points, it seems clear that the immediatel2 Science, 1926, 63, 401; A., 1063.l3 Proc.Nat. Acad. Sci., 1926, 12, 132; A,, 1063.l4 Amer. J.Phyeiol., 1925, 75, 131; A,, 1926, 1063.15 Compt, rend., 1926, 182, 1305, 1506; 183, 5, 267, 326; A., 869, 971.l7 Proc. Roy. Soc., 1926, [B], 100, 62; A,, 870.Ann. Report, 1925, 22, 223BIOCHEMISTRY. 239effects of insulin in the diabetio are an accelerated combustion ofsugar and the synthesis of a further quantity of glycogen. Theseworkers proved conclusively that no significant portion of thesugar which leaves the blood is stored in the muscles as a phosphoricester and that where excess of sugar is available a large proportionis deposited as glycogen in the skeletal muscles. Insulin hypo-glycemia lasting 1-3 hours does not appreciably reduce theglycogen reserves of the resting skeletal muscles of the preparationof spinal cat, the disappearance of glycogen from the muscles ofnormal rabbits under the effect of large doses of insulin being chieflydue to the convulsions.In an attempt to make a balance sheet of the glycogen-sugarsystem in the insulin-treated animal, Best, Dale, Hoet, and Marks1*were able to show that the reducing sugar which disappears from aneviscerated spinal preparation under the action of the hormone isequal to the sum of the glycogen deposited in the muscles and thedextrose equivalent of the oxygen absorbed.This balance ispreserved whether the blood-sugar is maintained a t a high level bythe infusion of dextrose or allowed to fall to a low level by restrictingthe supply. Similar conclusions have been reached by Bessingerand Lesser.’s@Much discussion still centres round the question whether insulin‘‘ activates ” the dextrose molecule by assisting to convert it intoa more readily oxidisable form.The original theory of Winter andSmith,l9 after being somewhat generally rejected, was revived ayear or more ago in a modified form by Lundsgaard and Holb011.20The latter investigators have during the year under review publishedseveral more papers in support of their theory that ‘( new glucose ”is formed from =-p-dextrose under the influence of insulin and anessential factor derived from muscle-tissue.21 Both their methodsand the interpretation of their results have been rather severelycriticised, for example, by Paul 22 and by Anderson and Carruthers,aso the whole question must still b e regarded as an open one, par.ticularly in view of the experiments of Visscher.24In connexion with the studies on the nature of the substances thatwill relieve the symptoms of insulin hypoglycsmia in animals, it isinteresting to note that glyceraldehyde is ineffe~tive.~~ In view of18 Proc.Roy. SOC., 1926, [B], 100, 5 5 ; A., 870.ls@Biochew. Z., 1926, 168, 398. lW A m . Report, 1922, 19, 195.20 Ibid., 1925, 22, 224.21 J. B i d Chew., 1926, 68, 457, 476, 485; 70, 71, 79, 83, 89; A., 861,2s Biochem. J., 1926, 20, 656: A., 861.2 4 Amer. J. Physiol., 1926, 76, 59; A,, 636.2 5 Reeves and Hewitt, J . Phyaiol., 1926, 61, Proc. XXXV; A,, 1063.1171. pa Ibid., 1920, 68, 425; A., 869240 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the disputed position of this substance in the table of normaldegradation products of glucose, this evidence is of considerablevalue, particularly as dihydroxyacetone, on the other hand, servesto restore the blood-sugar level.2sThe conversion of dihydroxyacetone is, however, according toMason 27 and also Kermack, Lambie, and Slater,28 neither rapid norquantitative.Glucosan and its polymeride, tetraglucosan, arealleged to be of vaIue in the diabetic organism and they have beenused to some extent in Germany for treatment. Deuel, Mandel, andWaddell 29 and Winter 30 could find no justification for this practice.Glucosamine 31 and glutose 32 are of no value in counteractinginsulin symptoms, but gl~ca1,3~ possibly because of its readyoonversion into mannose, is of service.Glycolysis.Much attention has been paid to the phenomenon of glycolysisduring the past year and several important papers have appeared.Considerable interest attaches to the experiments of Irving,34 fromwhich it is deduced that the rate of disappearance of dextrose froman isotonic saline solution in which erythrocytes are suspended isindependent of the initial concentration, being linear over a widerange of values.The temperature coefficient between 27" and 3 7 Ois 2.1. On what appear to be adequate grounds, the conclusion isreached that the degradation of glucose, if not its oxidation, is asurface reaction as far as the corpuscle is concerned and that it doesnot appear to involve the intervention of an organic phosphorus~ornpound.~~a Confirmation of the rate of glycolysis being in.dependent of the initial concentration of sugar is provided byHolb~ll's experiments on both normal and diabetic bloods.35 Otherstudies of the conditions affecting the rate of glycolysis in blood arereported by the last-mentioned investigator 36 and by Brugsch andHor~ters.~'The fundamentally important nature of the conversion of sugar26 Campbell and Hepburn, J . Biol.Chem., 1926, 68, 675; A., 979.27 J . Canad. Med. Assoc., 1926, 16, 367; A,, 1054.** Biochem. J., 1926, 20, 486; A., 861.a* Proo. SOC. Exper. Biol. Med., 1926, 23, 431.30 Biochem. J., 1926, 20, 668.31 Moschini, Arch. ital. Biol., 1924, 74, 117; A., 1926, 1063.32 Benedict, Dakin, and West, J. Bid. Ohem., 1926, 68, 1 ; A,, 754.33 Winter, Biochem.J., 1926, 20, 668.34 Biochem. J., 1926, 20, 613; A., 854.31 Comppt. rend. Soc. Bid., 1925, 93, 1684; A., 1926, 1051.36 Ibid., p, 1681; A,, 1926, 1051.-37 Biochem. Z., 1926, 175, 90; A,, 1055.ah Ibid , p. 1320BIOCHEMISTRY. 24 1into lactic acid is being emphasised more and more every day. Twoyears ago, the Reporter directed attention t o the studies in War-burg's laboratory on the glycolytic powers of the cancer cell.38These results, received a t the time with some reserve, seem now tohave been adequately Rat carcinoma tissue convertssome 9% of its weight of glucose into lactic acid aerobically perhour, and sarcoma cells are slightly more active, these glycolyticpowers being 60-100 times higher than that of blood.40 Figuresof the same order are given by human tumour tiss~es.~1The inability of the tumour cells to oxidise fully the lactic acidformed by glycolysis is me11 illustrated by the experiments ofWarburg, Wind, and N e g e l e i ~ ~ .~ ~ ~ Blood loses about 577; of itsglucose in passing through the vesseIs of a tumour, as compared with18% on passing through the liver. The inefficiency of the oxidisingmechanisms for degrading lactic acid in tumour cells is such that66% of the glucose that disappears in passing through a tumourappears in the venous blood in the form of lactic acid. Mendeland Bauch question whether the lactic acid thus produced would besufficient, except in the case of very large malignant growths, toraise significantly the concentration of this acid in the blood.43Schumacher suggests, however, that determinations of lactic acidin the blood might be of diagnostic value in certain cases.43I n support of the work of Warburg and his colleagues, Bierichhas found that the lactic acid content of tumour tissues shows awide variation, the absolute limits lying about 100% higher thanthose for normal tissues.44 Little is yet known of the cause of thelowered oxidation in cancerous tissues.Holmes 45 has found that ingenera1 they contain abnormally small amounts of reduced gluta-thione, and may be slow in reducing the dipeptide added in itsoxidised form. Rat sarcoma and carcinoma tissue were found, onspectroscopic evidence, to be deficient in the respiratory pigmentoytochrome. Less definite findings are recorded by Bierich andHalle46 and by Bierich and Ro~enbohm,~' who conclude that theamounts of reduced glutathione and cytochrome in canceroustissues may show wide variations, whereas Thomson and Voegtlin 47afound tumours to be richer in glutathione than most normal tissues.38 Ann.Report, 1924, 21, 208.39 E.g., Ron& and Deutsch, KEin. Woch., 1926, 5, 1216.(0 Negelein, Biockem. Z., 1925, 158, 121.4l Stahl and Warburg, Rlin. Woch., 1926, 5, 1218.414 Ibid., p. 829.44 2. physiol. Chem., 1926, 155, 245; A., 860.4 5 Biochem. J . , 1926, 20, 812; A., 971.46 2. physiol. Chem., 1926, 158, 1 ; A,, 1169.4 7 Ibid., 1926, 155, 249; A., S60.42 Ibid., p. 1272. 43 Ibid., p. 497.wU J . Biol. Chem., 1926, 70, 801242 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Lactic Acid and Muscle.The disturbance of accepted ideas caused by Embden’s announce-ment last year 48 that the liberation of energy due to the formationof lactic acid is not limited to t’he phase of contraction of muscle basnow abated in consequence of a careful re-examination of thequestion by Meyerhof and Lohmann.Contrary to Embden,@ theyfind that the formation of lactic acid is coincident with contractionif moderate stimuli be employed.” When, however, muscle istetanised directly, much lactic acid is liberated during recovery.Meyerhof has isolated from muscle an enzyme preparation thatforms lactic acid from starch or glycogen a t a rate about two-thirdsof that brought about by the muscle-tissue i t ~ e l f .~ l The prepar-ation may be separated by filtration through a Berkefeld ‘ I candle ”into two constituents, both of which are essential. It forms lacticacid from hexosephosphates, but a t a slower rate than from starchor glycogen--a result that casts some doubt on the intermediateformation of phosphoric esters in this reaction.5aSome doubt has been expressed by Deuticke 63 as to the accuracyof the popular view that lactic acid is largely responsible for muscularrigor. According to his view the accumulation of acid leads t ochanges in the physical properties of the muscle colIoids, which, upto a certain point, are reversible. Beyond this point, even althoughrigor is not yet evident, the change, the inception of which is accom-panied by acid production, becomes irreversible and even if someof the acid be removed from the muscle, rigor nevertheless sets in.The changes in the properties of the muscle colloids are exemplifiedby the inability to esterify phosphoric acid, although the power tohydrolyse hexosephosphate is retained.Muscle in this conditioncannot hydrolyse glycogen because of the loss of the power to formthe hypothetical intermediate hexosephosphate.Closely related to these results are those recorded by Hoet andMarks,54 who investigated the rigor that sets in almost immediatelyafter death from ovordosage with insulin or prolonged administrationof thyroid. Such rigor is not due to accumulation of lactic or otheracid, but the determining factors are the absence of glycogen and adecreased amount of lactacidogen in the muscle.It is suggestedthat for the appearance of rigor there is needed a disappearance fromthe muscle of hexosephosphate, probably, as Deuticke suggested,4 8 Ann. Report, 1926, 22, 225.40 Embden, Hirsch-Rauffmann, Lehnartz, end Deuticlte, 2. physiol. CJlem.,60 Biochem. Z., 1926, 158, 128; A., 427.6 1 Pfliigef’o Arch., 1925, 210, 790.63 Z. physiol. Chem., 1928, 149, 259.64 Froc. Roy. SOC., 1926, [B], 100, 72.1926, 151, 209; A., 427.Naturwias., 1920, 14, 190BIOCHEMISTRY. 243as a consequence of a failure of the synthetic mechanism. T bwould occur either from exhaustion of the supplies of raw material,glycogen, or from actual damage or death of the synthetic mechanismitself.The hypothesis advanced by Poster that there may be twodistinct paths by which lactic acid can arise from carbohydrate inthe tissues seems now superfluous, since Dudley 55 has shown thatthe failure to detect glyoxalase in an aqueous extract of rabbit’smuscle was due to faulty technique.Considerable importance must be attached to the experimentalresults of Burn and Marks 56 in view of the light they cast on thesources of sugax in the body.The livers of dogs or cats that havebeen fed for some time largely on fat yield, on perfusion with bloodof the same species, a reducing substance, presumably sugar, a t therate of 2 to 4 mg. per g. of liver per hour. At the same time, theremay be an appreciable formation of glycogen. It has been satis-factorily demonstrated that the sugar does not arise from lacticacid, nor can more than a small fraction be accounted for by themetabolism of profein.It was impossible t o obtain clear evidencethat there was a disappearance of fat proportionate with the sugarformed, because the total amount of fat was so large and the per-centage in different lobes so variable. ‘‘ Nevertheless,” as theseinvestigators remark, “we know of no other source from whichthe sugar could have come.” The production of sugar in theseexperiments was not obviously influenced by insulin, adrenalin, orpituitary extract.Biological Oxidations.Once again it is the duty of the Reporter to devote a considerableproportion of his allotted space to this subject, because theyear under review has seen the publication of several papers ofoutstanding interest.In the first place, there is the important paper by Cannan, Cohen,and Clark,67 dealing with the reduction potentials of cell suspensions,which, together with the related study of Clark, Cohen, and Gibbs 58on the use of methylene-blue as an oxidation-reduction indicator,considers the fundamental questions underlying a vast amount ofrecent work on biological oxidations, too often inadequately con-sidered by some investigators.The electromotive behaviour of cellsuspensions in the absence of foreign reversible systems such SLB thewidely employed methylene-blue shows that electrode measurementss6 Biochem. J., 1926, 20, 314; A,, 640.6 6 J. Phyeiol., 1926, 01, 497; A,, 1055.s7 United Btstes Health Service Pub.1926, supp. 55 ; A., 1009.68 Ibid., Reprint No. 1017, 1925.See A., 1925, i, 1495244 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.can be substituted for such indicators and that the electrometriomethod has obvious advantages, not the least of which is theprovision of a continuous record of the full course of the reaction.In the presence of an indicator such as methylene-blue, titrationcurves are obtained from which it is possible, by utilising the datafrom experiments on the dye in pure buffer solution, to deduce thevelocity of reduction of the dye by the cell suspension with Iesstrouble and with an accuracy far greater than is possible in such atechnique as that described originally by Thunberg.The cellsuspension under anaerobic conditions gradually develops a morenegative potential, traversing the zones of the series of reversibleindicators employed in oxidation-reduction studies by Clark.Should one of these dyes be present, the potentials pass smoothlyinto the equilibrium potentials of the dye system, the dye is pro-gressiveIy reduced, and the potentials then pass smoothlyout of thatparticular zone.This behaviour could be explained if one made the reasonableassumption that small quantities of active poising material werebeing slowly liberated from a large reserve. Tentatively it is sug-gested by the authors that this rep$esents the ‘‘ intramolecularadjustments of electronic structures into forms to which the electro-chemical considerations may be applied ”; in other words, oneform of what is now somewhat generally termed “ activation ” ofmolecules.Certain of the facts revealed by this study suggest that thereexists a correlation between the characteristic potential and themetabolism characteristic of species, but this question touches onthe fundamental problem of the relation that the potentials of a cellsuspension bear to conditions within the intact cell, on which as yetlittle trustworthy information has been gained. The authors ofthis most interesting paper sound many warnings that should beborne in mind by students of these problems.Not the leastimportant of these is the suggestion that the events of aerobiosis andthose of anaerobiosis should be sharply differentiated.The widespan covered by the potentials of anaerobic cell suspensions probablyrepresents a condition entirely distinct from that which exists in theaerobic state, in which it is conceivable that a dynamic equilibriumbetween reductive and oxidative reactions permits a more or lesspermanent stabilisation of the system.If so, there may be, as Needham and Needham think,5* a definitelevel of potential inside the living cell.From these considerations it is obvious that in the ‘’ methylene-blue technique ” of Thunberg and similar methods of studying5a PTOC. Roy. Soc., 1925, [B], 98, 259BIOCHEMISTRY. 245anagrobic oxidations, only one narrow part of the whole reducingzone of the cell suspension has been selected.Since the addition of methylene-blue a t once poises the potentialof the suspension a t a position outside the range of aerated prepar-ations, the question arises as t o the relation of events occurring in thepresence of methylene-blue and those in the true anaerobiosis ofthe cell.Cannan, Cohen, and Clark have also paid some attention to thestudy of the washed-tissue system so extensively employed byHopkins and by Thunberg.Exhaustive washing yields a prepar-ation that holds the electrode most erratically, the tendency towardsnegative potential disappearing as the water-soluble componentsare removed. The addition of any one of Thunberg’s “meta-bolites ” (e.g., succinete) a t once causes the electrode to register thetypical steady trend towards the negative potential, presumably asactivation of their molecules occurs, Washed tissues which failto reduce methylene-blue still actively reduce 2 : 6-dichlorophenol-indophenol and do so after boiling or in the presence of molecularoxygen. The reducing substance can be removed by alcoholextraction and may be, in part, the thermostable “ hydrogendonators ” described by Hopkins and Meyerhof.60 These electro-chemical studies also confirm the observation that cells containthermostable ‘‘ hydrogen donators ” capable of reducing gluta-thione, it being noted in passing that the potentials of themethylene-blue system render it particularly suitable for the studyof this particular oxidation-reduction system.No less important is the stimulating paper by Quastel 61 ontheory of the mechanisms of biological oxidations and reductionsdeduced from a study of the dehydrogenations produced by resting,that is, non-proliferating, bacteria.As this author remarks, ‘‘ Novery obvious chemical connexion appears to exist between thosemolecules capable of performing the functions of a hydrogen donatorin presence of bacteria or muscle-tissue and it seems necessary, inorder to comprehend the activity of these molecules, to resort to ahypothesis which claims that for every such molecule there is,related to it, some specific enzyme.” Thus Bacillus coli was foundto activate 56 substances out of 103 that were examined, and theprospect of having to admit the existence of 56 specific “ hydrogentransportases ” was sufficient to lead Quastel to question whethersome more satisfactory explanation could not be found.In the fistplace, he examined the question of the site of activation. Obviouslythis change does not occur in the surrounding medium, since thiswould postulate that the thermolabile catalysts, for some agent of6o Ann. Report, 1922, 19, 189. Biochen. J., 1926, 20, 166; A,, 434246 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.this type is known to play a part, act extracellularly. On reason-able grounds it is shown that the site of reduction of methylene-blue ia probably not in the interior of the cell, so that the conclusionis reached that this change occurs a t the cell surface,If activation of the substrate occurs a t a cell interface, notnecessarily the surface, the molecule would revert to a ‘‘ normal ”condition when it is out of contact with the structure.On thesegrounds, it would seem reasonable to assume that the important siteof activation is where the reduction of the methylene-blue occurs,namely, a t the cell surface.Based on the theories of orientation of Hardy, Langmuir, andAdams, the author has attempted to picture a cell surface overwhich are scattered many locally intense electric fields, which,together with the electrical condition of the molecule itself, must,as J. J. Thomson has pointed out,62* 1 3 ~ induce “ activation ” byvirtue of their distorting influence on bonds between atom andatom. Thus an acid of the type A-CH=CH-C0,H may beregarded as assuming the activated form A-C-CH,-CO,H, ifA be a radical having no directive influence on the movement of theproton ; the effect of the carboxyl group (17 electrons) being to pro-duce electric fields a t the a-carbon atom, and to a far less extent a tthe p-atom, that will attract positive electricity.Hence on oxid-ation, that is, addition of negative electricity, the p-carbon atom willbe the one affected.Thus, for example, fumaric and crotonic acids on activation maybe regarded as CO,H*C*CH,-CO,H and CH,C*CH,*CO,H, respect-ively. Therefore, fumaric acid will attract hydrogen because ofthe field acting a t the unsaturated carbon, whereas activatedcrotonic acid, owing to the effect of the methyl radical, shouldbe less readily reduced and more readily oxidised.Experimentsshow this to be true.Thie attempt by Quastel t o introduce electrochemical con-siderations into biochemical oxidation-reductions is noteworthy, andwould seem to find experimental justification in the studies ofCannan, Cohen, and Clark already discussed above.It does not follow that the existence of specific catalysts need bedenied. The structure of the cell surface, or, for that matter, of allthe cellular surfaces, is an assemblage of inseparable enzymes. Itis, however, unnecessary to postulate the existence of a large numberof distinct enzyme systems dealing with oxidations and reductionswhen it is possible to regard specificity of behaviour as belonging tothe molecules rather than to the enzymes.** Phil. Mug., 1923, 46, 506; A , , 1923, ii, 682.vv \/a* NatuTe, 1923,112,826BIOCHEMISTRY a 247Bearing on this work and on that of Cannan, Cohen, and Clark,are the observations of Kodama,6Q that hypoxanthine and aldehydegive no reduction potential when activated by xanthine oxydase,but do so in the presence of methylene-blue or oxygen.He statesthat in the former case the potential is merely that of the dye, whilstin the latter it is that of hydrogen peroxide. The failure to demon-strate the development by activated xanthine a t an inert electrodeof a reduction potential consistent with its reducing power suggeststhat we are not yet entitled to generalise from the observations ofCannan, Cohen, and Clark. A better appreciation of conditionsgoverning the behaviour of inert electrodes in such irreversiblesystems seems t o be necessary to further progress in this matter.Xanthine oxidase shows a high degree of specificity towards thehydrogen donator, but, as far as has been ascertained, none towardsthe acceptor.66has filled in a very important gap in our knowledge of theaction of tyrosinase on tyrosine by isolating 1-3 : 4dihydroxy-phenylalanine in small amounts as a product of the reaction.It isitself rapidly oxidised by tyrosinase to the unstable red pigmentpreviously described,67 the stages being probably :O H ~ , - C H ( N H , ) . C O , H + OHRaperCH,*CH( NH,) +CO,H(red, unstable compound) --+ melanin.The conversion into melanin is believed to be a simple rearrange-ment, because this substance contains almost the same percentageof nitrogen as its red precursor.The isolation of 3 : 4-dihydroxyphenylalanine is an importantstep, for it not only places on a firm basis the experimental work ofBloch 88 on pigment formation in skin, but overcomes an obstaclewhich previously made one hesitate to accept the view that tyrosineis the parent substance of adrenaline.Closely related to these studies are the remarkable results of theinvestigations of Harrison and Garrett 6Q on the induction ofmelanism in certain moths.Observation of these species, of which*' Biochem. J., 1926, 20, 1095; A., 1175.66 Ibid., p. 703; A., 977. 66 Ibid., p. 735 ; A., 977.6 ' Compare Ann. Report, 1925, $22, 236.6 a 2. phyaiol. Chem., 1916-17, 98, 226.6* Proc.Roy. Soc., 1926, [B], 99, 241248 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Silenia bilunaria is typical, proved that the moths in the vicinityof large towns are usual19 darker in colour than those in the country.The obvious explanation that this was due to natural selection notbeing found adequate, other causes were sought, with the resultthat the melanism waa traced to a constituent of their food. Lamsreared on plants exposed to the fumes and smoke of factoriesdeveloped a large proportion of melanic forms, and the actualexciting factor was shown t o be small traces of manganese or leadin the sooty deposit on the leaves.The melanism could be induced with ease by feeding the larvaon natural fresh food whioh had been watered with a very dilutesolution of manganese sulphate or lead nitrate.The amazing feature of the results is, however, that, once induced,the melanism is inherited, usually as a Mendelian recessive.Thefact that in one species the acquired character was a dominant leadsthe authors to reject the hypothesis that the melanism was latent.Y'he Chemistry of Specific Reactions.In the Annual Report for 1923, the Reporter directed attentionto the progress that had then been made in the study of the chemicalnature of the specific bacterial substances. Further evidence thatthe specific substances of certain types of organism are either them-selves polysaccharides or, are intimately associated with suchcompounds has accrued.Heidelberger, Goebel, and Avery,70 in a series of papers, describethe isolation of substances with specific properties from the Estrain of Friedlander's bacillus and from Pneumococcus type 11.In both cases the active substances are nitrogen-free, dextro-rotatory polysaccharides, yielding mainly glucose on hydrolysis,and with marked acidic properties.Similar results are describedby Laidlaw and D ~ d l e y . ~ ~ a Heidelberger and his colleagues statethat the specific substance of Pneumococcus type 111 is a Isevo-rotatory, nitrogen-free polysaccharide containing glucose andglycuronic acid, whilst that of type I contains nitrogen, possibly,it is suggested, as a nitrogenous sugar derivative linked togalacturonic acid.Siebert and Long,71 in a series of papers on the chemical natureof the active principle of tuberculin, have described the separationof a protein with which the activity is associated.By treating thisproduct by Hopkins's method for isolating crystalline ovalbumin,70 J. Exp. Med., 1925, 42, 701, 709, 727; A., 1926, 545.7QaBrit. J . Exp. Path., 1925, 6, 197,Amer. Rev. Tubercu~osis, 1926, 13, 393; A,, 1178BIOCHEMISTRY. 249a crystalline product was obtained which gave typical proteinreactions and a marked biological reaction in tuberculous animaki2The complex system known to serologists as complement has beenexamined with considerable care by Gordon, Whitehead, andWormall.73 To the recognised three factors, (1) the globulin com-ponent (mid-piece), ( 2 ) the albumin component (end-piece), and(3) a heat-stable factor usually associated with the globulin fraction,they have added a fourth factor, also thermostable, which is anessential constituent of the haemolytic system.This fourth factoris associated with the albumin fraction, is inactivated by ammonia,and is not dialysable. Serum that has been inactivated by am.monia retains its opsonic activity, so that the fourth factor may beregarded as playing no part in opsonic action.Studies of the diffusible and non-diffusible calcium of serumindicate that the latter fraction is connected with complementactivity ; some parallel may be traced between the calcium contentof various fractions and the power to replace or reactivate theammonia-treated serum. Attempts to reactivate this material byaddition of calcium in various forms were, however, unsuccessful.No alteration in dialysable calcium occurs during the inactivationwith ammonia.Hemoglobin and Related Pigments.Advances of the first order of importance have been recorded inthis field of research during the past year, and encourage one in theview that we are a t last gaining a clear knowledge of the chemicalstructure of these respiratory pigments as well as of their truebiological significance.How far our knowledge of hemoglobinhas been extended during the past few years is clearly revealed inthe masterly presentation of the subject made before the ChemicalSociety early in this year by Professor Barcroft,7* in whose laboratory~t large proportion of the advances have been made.The syntheses of etioporphyrin and etiohaemin by Pischer andKlarer from 2 : 3-dimethyl-4-ethylpyrrole is an outstanding event,since they forecast the synthesis of the related dicarboxylic acidhaematix~.~~Apart from this narrow gap, the synthesis of hemoglobin has inone sense been effected, because Hill and Holden have succeededin combining purified globin with free hsmatin between the pH limitsof 5 and 9 and converting the product into oxyhemoglobin spectro-scopically indistinguishable from the natural substance.76 The72 Science, 192G, 63, 619; A., 1062.73 Biochem.J., 1926, 20, 1028, 1036, 1044; A,, 1166.7 4 J., 1926, 1146; A., 760. 7 6 Annden, 1926, 448, 178; A., 962.7 6 J.'Phy.&ol., 1926, 61, XXII260 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.demonstration by Keilin 77 that ‘‘ acid hsmatin ” prepared fromoxyhemoglobin is the same as ‘‘ oxidised hem ” prepared fromh m i n clears up one more point of confusion for which the oldernomenclature was to a large extent responsible.The relation between the blood pigment derivatives may there-fore be represented by the following arrangement :acid Hematoporphyrin Oxidised hsm +- Oxyhsmoglobin t X k JHem alkali HBmin -AArtificial Hzemochromogen 7 HaemoglobinSeveral points of interest stand out from the recent researchesrepresented by this chart.The combination of the acidic hemwith basic substances of many types to give a variety of hsmochrom-ogens is in itself vastly interesting, but it is indeed remarkable thatwhereas their formation usually demands a great preponderance ofthe components, the combination between globin and ham isalmost complete.Moreover, the globin complex is one of the fewhemochromogens that are soluble in high degree, and seems to beunique in its property of passing into hsmoglobin on adjustment ofthe hydrogen-ion con~entration.~~The artificial production of metallic compounds of the porphyrinsstudied in detail by Hill 79 has also revealed many curious pointsthat are of considerable significance from the standpoint of thebiological value of haemoglobin. Many metals-iron, nickel,cobalt, manganese, zinc, copper, silver, potassium, eta-may becombined with porphyrin to yield compounds which Barcroft woulddescribe as being on the “ h a m level.” Of these, only three,namely, the complexes with iron, manganese, and cobalt, have thepower of being oxidisable and reducible, and only one of these, theiron compound, has a spectrum that suggests ham rather thanhremochromogen.Furthermore, i t is ody this one compound thatwill unite with globin or other basic compounds to yield true hsmo.‘7 PTOC. Roy. SOC., 1926. [B], 100, 129; A,, 857.‘ 8 Anson and Mirsky, J. Phyaiol., 1925, 69, 50.79 Biochem. J . , 1925, 10, 341.hsemochromogens (alkaline hrematinBIOUHEMI8TRY. 26;lchromogens. This work throws .light on the nature of other pig-ments such as turacin, which is a copper-porphyrin compoundincapable of uniting with basic nitrogen compounds and notexhibiting oxidation and reduction reactions.From a study of the relation between turacin and hematinKeilin 80 is inclined t o believe that cytochrome may be a modifiedhaemochromogen compound present in two distinct degrees of dis-persion, there being evidence that the u- and p-haemochromogensdescribed by Anson and Mirsky 81 differ only in their dispersion.Schamm 82 reports a study of cytochrome and the related myohsm-atin of MacMunn, in which he confirms Keilin’s original observ-ations and traces a relation between the porphyrin of these pigmentsand u-hsmatoporphyrin.A very careful and much needed re-examination of the methodsemployed for measuring the osmotic pressure of hsmoglobin hasbeen made by Adair,83 who has elaborated a technique that seemsabove criticism.The osmotic pressure measured on dialysedhaemoglobin by previous investigators ranged from 3.5 to 12 mm.%of protein.Re-determinations by means of the improved methodgave values of 3.2 mm. or less, and it has been shown that highervalues are obtained only when acid or base remains bound to theprotein, or when the experimental conditions are otherwise un-satisfactory.The smallest possible molecular weight of the pigment being16,700, Adair’s estimate of the value of n as 4 gives an absoluteweight of 68,000.Discussion still centres round the question of the oxygen contentof methsmoglobin. Nicloux and Rochead maintain that it con.tains one atom of oxygen less than oxyhsmoglobin and one atommore than hsmoglobin, whereas Conant and Scott,a5 criticising theexperimental procedure of Nicloux, assert that methmoglobincontains only one-fourth as much oxygen as oxyhsmoglobin.Vitamins.Vitamin-A,-No progress has been recorded during tho past 12months in the direction of ascertaining the chemical nature of thissubstance, but Weidemann,s6 during his studies of the substancespresent in the unsaponifiable fraction of the oil from the livers ofKeilin, Proc.Roy. Soc., 1926, [B], 100, 129; A,, 857.Ann.. Report, 1925, 22, 238.2. phyeiol. Chem., 1926, 152, 55, 147; A,, 537.83 Proc. Roy. SOC., 1925, [B], 98, 523.84 Bull. Boc. Chim. biol., 1920, 8, 71; A., 780.0 5 J . Bwl. Ohm., 1926, 60. 675. ( 6 Bioohern. J., 1926, 20, 686252 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Greenland sharks, Xomniosus microeephlus, has conhmed theobservation of Drummond, Channon, and Coward 87 that neitherbatyl alcohol nor selachyl alcohol possesses growth-promotingproperties.The colour reactions described by Rosenheim and Drumm0nd,8~and believed by them to be due to vitamin-A and possibly suitablefor its quantitative estimation, have been further studied by Carrand Price, 88 whose modifications, employing antimony chlorideand an evaluation of the colour by means of the standard glasses of aLovibond tintometer, are great improvements. Their evidencegoes to support the idea that the blue colour is produced from thevitamin.Fearon 89 has described another colour reaction, given by certainproducts containing vitamin-A on treatment with pyrogallol in thepresence of trichloroacetic acid and an oxidising agent.Thepermanence of the red colour produced seemed a t first to indicatethat it might be very suitable for purposes of assay, and support forthis view was advanced by Willimot and Moore 9o and by von Euler,Myrback, and Karl~son.~lFurther study, however, has revealed that the reaction describedby Fearon is not associated with the presence of the vitamin ; thechromogenic substance passes, on saponification of an oil in which itis present, into the fatty acid fraction, whereas the vitamin passesinto the unsaponifiable residue.92 The substances responsible forthe two colour reactions can thus be separated ; moreover, certainsubstances have been found, e.g., sardine oil, which give a strongFearon reaction but do not respond to the test with arsenic orantimony chloride. Such products are found to be devoid of growth-promoting activity when tested on animals.The non-specificity ofFearon’s test is confirmed by Willimot, Moore, and woke^.^^Vitamin-B.-Ever since the discovery of this dietary factor, orfactors, for it is still uncertain whether one or more than one sub-stance is responsible for the physiological action of extracts of yeast,wheat embryo and rice polishings, speculation has been rife regard-ing its r81e in the animal organism, In one or two directions, therehas been a tendency for these speculations to take dehite shape,and in none more than in that which views this vitamin as playingan essential part in the oxidative mechanisms of the tissues.A considerable amount of experimental evidence has been pre-Ann. Report, 1925, 22, 219.** Biochem. J., 1926, 20, 497; A., 870.89 Ibid., 1925, 19, 888; A., 1920, 207.8o Ibid., 1926,20, 869; A., 980.91 2. physiol. Chem., 1926, 157, 263; A,, 1181.a2 Lancet, 1926, 11, 806; A., 481. 88 Biockem. J., 1926,20, 1292BIOCHEMISTRY. 253sented in support of this idea, particularly by Abderhalden and byHe~s.9~ The latter investigator holds the clear-cut view that theyeast-vitamin is either the mother-substance of the oxidisingenzymes or is essential to their formation in the tissues. Abder-halden has not committed himself to so clearly-defined an opinion,but shares with Hess the general view that the oxidative powers ofthe cell are greatly lowered in the absence of vitamin-B.The main evidence in support of their case is provided by the factthat animals suffering acutely from a deficiency of this vitaminexhibit greatly lowered body-temperature and oxygen uptake.Additional support is derived from experiments which it is claimeddemonstrate that isolated tissue and cell suspensions show diminishedrespiration unless adequate amounts of the vitamin-B are added.The greater part of these studies has been recently submitted tore-examination, with the result that doubt is cast on the accuracy ofthe conclusions of Hess and Abderhalden.95 Investigations of theoxygen uptake and oxidising power of suspensions of tissues removedfrom animals suffering from a deficiency of vitamin-B gave resultsclosely agreeing with those obtained with normal preparations.I n studies of the intact animal (rat) confirmation of the fall ofbody temperature and gaseous metabolism was obtained, but theywere observed to occur only shortly before death and to resemblein many ways the similar conditions in the premortal stage ofinanition.Comparative examination revealed the fact thatstarvation plays a very large part in the chain of events that followa deficiency of vitamin-B, because, as Mendel and Cowgill haveshown, this dietary principle is related in some essential mannerto the complex phenomenon of appetite. In the absence ofvitamin-B the food consumption falls until the animal is virtuallystarving, and it remains to be discovered whether there is any otherconsequence of the deficiency more obscure than this.It must beborne in mind that the greater part of this investigation was carriedout on rats, so that the actual relation of the results to the con-ditions in birds and man known as avian polyneuritis and beri-beri,respectively, is as yet uncertain. I n the rats there was no appreci-able difference between the nerve lesions noted in vitamin-Bdeficiency and in simple inanition.Vitamin-D.-In last year’s Report an account was given of theinteresting and important discovery that highly purified cholesterol,after exposure to ultra-violet radiation, was endowed with anti-rachitio properties similar to those by which the vitamin-D has beencharacterised. Further work reported during the past 12 monthsOL &.physiol. Chem., 1921,117, 284; A., 1922, i, 399.O S Drummond and Marrian, Biochem. J . , 1926, 20, 1229254 ANNUAL REPORTS ON THE PROQRESR OF CHEMISTRY,has maintained the extraordinary interest in this subject. BiIh @*has detected antirachitic powers in the resinous product isolatedfrom cholesterol after boiling with previously ignited fuller's earthin carbon tetrachloride, benzene, or xylene. No active preparationswere made when ethyl acetate or various alcohols were used assolvents. In a later paper,g7 he described the isolation of LIproduct, supposed to be C,,H,,,O,, believed by him to be apolymerised cholesterol, which itself possessed no antirachiticproperties, but which he considered to be an intermediate productin the formation of the active substance.The evidence he adducesin support of this view is, however, of the slenderest nature.Rosenheim and Webster,Qs by removing the unchanged choleaterolfrom the irradiated product by precipitation with digitonin, wereable to concentrate the antirachitic activity in the filtrate, theirpreparation being physiologically protective to rats in doses as smallas 0.01 mg. daily. Hess, Weinstock, and ShermanQg did not a tfirst succeed in effecting this separation, because they irradiatedtheir material in air, whereas Rosenheim and Webster employed anatmosphere of nitrogen; later they were able to confirm the state-ment that oxidation of the active substance may occur duringexposure and result in a reduced yield.99@This fact throws doubt on the correctness of the view of Vollmerand Serebrijski,* that the antirachitic activation of cholesterol isessentially a peroxide formation. The uptake of oxygen noted byhim and by Hamano seems entirely unrelated to the phenomenonof vitamin formation.In an attempt to correlate the production of the vitamin with theknown structural units of the cholesterol molecule, Rosenheim andWebster 3 have studied a large number of derivatives and relatedsubstances-cholesteryl chloride, cholestene, cholestenone, copro-sterol, a-amyrol, and the possibly related hydrocarbon squalene(see later) were not rendered antirachitic by ultra-violet light, butactive preparations were made from ergosterol and the acetate andpalmitate of cholesterol. These facts seem to point to thenecessity of the secondary alcohol group and the unsaturated linkingbeing intact before activation can occur. An extension of thesestudies recently reported has forced the authors to express another08 J . Biol. Chem., 1926, 67, 7 6 3 ; A., 646. *' Bills and McDonald, J. BioZ. Ohem., 1926, 68, 821; A., 981.Biochem. J . , 1926, 20, 537; A., 870.I@ J . Bwl. Ohem., 1926, 67. 413; A,, 646.@*a Hese, Weinstock, and Sherman, ibid., 1926, 70, 123; A., 1182.1 Biochem. Z., 1926, 176, 84; A., 1181.IM., 1926,109. 432 ; A., 646.Rosenheim and Webiter, J . SOC. Chem. h d . , 1926, 46, 932BIOQHEAUSTRY. 266view, because it was found that a specimen of cholesterol regeneratedfrom the dibromide could not be activated by ultra-violet light.The proffered explanation is that I r pure ” cholesterol prepared inthe usual manner may, even after repeated saponification andrecrystallisation, retain traces of an impurity which is the precursorof the vitamin, and for which the name vitasterol is proposed. Treat-ment with bromine irreversibly changes this substance as far a8 itspower to give rise to the vitamin is concerned, so that cholesterolregenerated from the dibromide cannot be activated.This conclusion confirms that deduced by Heilbron, Kamm, andM ~ r t o n , ~ from an entirely different line of argument. In repeatingthe work of Hess and of Schultz and Ziegler on the absorption bandsof cholesterol, these investigators observed that the absorptionspectrum of “ pure ” cholesterol was apparently a compound one.By fractional crystallisation of 2 kg. of the raw material they con-centrated a least soluble fraction, weighing 5 g., which exhibitedthree well-defined absorption bands a t 293, 280, and 269 pp, whilstthe purified cholesterol showed only general absorption in theultra-violet. These characteristic bands disappeared when thissubstance mas irradiated in alcoholic or ethereal solution, and thesuggestion is advanced that such a product is, in view of theseproperties, more likely to be the precursor of the vitamin than purecholesterol. In this connexion, it may be recalled that Hess6showed some years ago that the curative rays of the spectrum in thedirect treatment of rachitic children by light have wave-lengthsin the vicinity of 290 pp.Spermine.The researches into the constitution of this interesting tissuecomponent reported last year have been continued duringthe past 12 months. Dudley, Rosenheim, and Starling7 foundthat destructive distillation of the hydrochloride yielded pyrrol-idine, whilst decamethylspermine sulphide on degradationyielded hexamethylspermine and tetramethyltrimethylenediamine,NMe,*[CH,],.NMe,.This evidence suggested the presence of the chains N-GGGNand N-GGGGN in the molecule, which together with the factthat there are two amino- and two imino-groups present suggestedtwo alternative formula :(a) NH,~[CH2’],-NH~[CH2]4*NH*[CH2]8*NH, and(b) NH2*[CH,],~NH~[CH,],*NH~[CH2],*NH,.J . Soc. C h m . Ind., 1926,46, 932.J . Biol. Chem., 1926,69,415; A,, 1065.J. Amer. Med. ABBOC., 1922, 78, 1596.Biochem. J., 1926,20, 1082; A,, 1128256 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The synthesis of the compound (a) was accomplished by con-densing a6-diaminobutane (putrescine) with y-bromo-u-phenoxy-propane. Treatment of the resulting a6-bis[y'-phenoxypropyl-aminolbutane with hydrobromic acid resulted in replacement of thephenoxy-groups by bromine, and the subsequent action of ammoniagave the required et6-bis[~'-aminopropylamino]butane. This com-pound was found to resemble the natural base in all respects.Most of the observations reported by Wrede 8 agree with theformula established by Dudley, Rosenheim, and Starling. Thesame investigators have also examined the constitution of a relatedbase, termed spermidine, which accompanies spermine in extractsof animal tissues.9NH2~[CH,],-NH*[CH,],.NH,This substance appears to beand its synthesis has been achieved.J. C. DRUMMOND.H. J. PAGE.8 2. physiol. Chem., 1926, 153, 291; A,, 751. * Report of the Meeting of the Biochemical Society, Nov. 8th, 1926;J. SOC. Chem. Ind., 1926, 45, 839

ISSN:0365-6217    

DOI:10.1039/AR9262300209

出版商:RSC    

年代:1926

数据来源: RSC

摘要:

CRYSTALLOGRAPHY.SECTIONS of the subject which have been selected for special treat-ment in this Report are “ The Dynamics of the Crystal Lattice ” and‘‘ The Intensity of X-Ray Reflexion.” The former has not beendealt with in the Annual Reports for several years and considerableprogress has been made, although our knowledge of the forcesbetween atoms is still so fragmentary. The immense importanceto chemistry of a precise examination of the forces in crystals needhardly be emphasised. A discussion of the “ Intensity of X-RayReflexion ” has been included in this Report on crystallography,because the successful examination of crystalline structure isdependent on a knowledge of the laws which govern reflexion.Every advance in this knowledge implies a correspondingly greaterpower of examining the finer details of structure.I n order to keepthe Report within the allotted length, certain other aspects havebeen touched on very briefly. The structures of metals and alloys,and the study of imperfectly crystallised bodies have been dealt withrecently and do not form the subject of special sections in thepresent Report.‘‘ Die Verwendung der Rontgenstrahlen in Chemie und Technik,”*by Hermann Mark, mill be welcomed by crystallographers. Markwrites with authority, for he has won general recognition as a mostdistinguished experimentalist amongst those who are investigatingcrystalline structures in Germany. The book is a valuable additionto the existing literature, because the author’s point of view differsfrom that adopted in other well-known books.Mark devotesmuch space to the technique of X-ray analysis, and to the technicalapplication of the results which can be obtained, the book beingdesigned for the use of those who are engaged in industrial research.The article on “ X-Ray Diffraction Data from Crystals andLiquids ” in the International Critical Tables, by R. W. G. Wyckoff,contains a valuable summary of experimental observations. It isregrettable that the author has, in these International Tables,replaced the time-honoured Schoenflies notation of space-groups byone which he has devised himself, for although Schoenflies’s notationis not ideal and more consistent systems might be found, it has* “ Handbuch der Angewctndten Physikaliachen Chemie,” Ed.XIV,Barth, Leipzig.2 57REP.-VOL. XXIII. 258 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the merit of being universally accepted and is familiar to all crystallo-graphers. It would be preferable to examine alternative notationsvery thoroughly and to obtain a general consent before replacingSchoenflies’s historical terminology, as i t is of prime importanceto avoid the confusion caused by several systems. The structuresaro so described in the tables that the atomic positions can be foundby consulting Wyckoff’s book, “ The Structure of Crystals,” as akey. A striking feature brought out by the tables is the simplicityof the compounds which have as yet been analysed a t all completely,and the small number of crystal types which account for the majorityof forms.It emphasises the limitations of the new science, whichhas as yet succeeded in mastering so few of the more complexstructures.An article on the structures of solids and their analysis by X-raysby P. P. Ewald * has recently appeared in the “ Handbuch derPhysik” series. The article describes the standard methods ofanalysis and summarises the results. It is no easy task to selectfrom the large number of published analyses those which may berelied on with confidence, and to judge to what extent these analysesare definite and where they become speculative. Ewald gives avery good critical review of the subject, illustrating the structureswith excellent figures. The introduction to the study of crystalsymmetry is well planned to help the student, giving all the necessaryideas while being much less formidable than the treatment by otherauthors.Crystalline Symmetry and Etch-Figures.K. F.Herafeld and A. Hettich 1 have studied the etch-figures ofsylvine, potassium chloride. If their conclusions are substantiated,it will be necessary to revise accepted ideas about the relationshipbetween the symmetry of a crystalline structure and the externalsymmetry displayed by the crystalline faces, or by etch-figures.Sylvine has been assigned by the mineralogist to a hemihedral(holoaxial) class of the cubic system because the four-sided figureswhich appear when a cube face of the crystal is etched are oftentwisted from the symmetrical position, and all in the same direction.Herzfeld and Hettich claim (1) that all potassium chloride crystaleof a crop etched by the same solvent show figures twisted in thesame sense, whereas one would expect half the crystals to be right-handed and half left-handed; (2) that when precautions are takenagainat all contamination by impurities, particularly by organicSee elso A.Hettioh, 2. Hnkt., 1926,64,* ‘‘Handbuch der Physik,” B a d XXIV, pp. 191469. Springer, Berlin.1 2. Physik, 1926, 38, 1; A., 589.265CRYSTALLOGRAPBY. 259matter, the etch-figures are always symmetrical. They concludethat the asymmetryis to be traced to impurity in the etching fluid, notto the crystal structure. If a trace (0.1 mg.) of optically active amylalcohol be added to the purified system, the etch-figures are greatlyincreased in number and again indicate holoaxial symmetry bybeing twisted. Similarly, if a crystal which only shows symmetricalfigures be removed from the solution, touched with the h g e r , andreplaced, unsymmetrical figures appear.The lowering of symmetryis ascribed to small traces of organic matter which has the asym-metry of an optically active substance, and is absorbed on thecrystal face. J. J. P. Valeton2 criticises these conclusions, anddenies that two faces of a crystal which belong to the sameform can be acted on differently by a foreign body. Itappears, however, that Herzfeld and Hettich are justified indrawing their conclusion that this difference is possible. Two facesof a crystal derived from each other by a symmetry operation of thefirst sort, such as rotation about an axis, must be identical in allrespects, but two faces related by an operation of the second sort(reflexion) present surfaces which are the mirror images of eachother as regards conformation. An optically active moleculemay be adsorbed on the one face and not on the other, and it istheoretically possible that the presence of an active substance maycause a holosymmetrical crystal to appear holoaxial in the develop-ment of either its faces or its etch-figures.If this very interesting conclusion is verified by further investig-ation (the attempt to reverse the figures by using amyl alcohol ofopposite rotatory power has not yet been made), it casts light on apuzzling problem.Crystallographers have, for instance, assignedpotassium chloride, ammonium chloride, cuprous oxide, and barium,strontium, and lead nitrates to holoaxial classes. These crystals donot rotate the plane of polarisation of light, and in each case X-rayanalysis assigns a structure of higher symmetry (cubic holohedralto the Grst three, pyritohedral to the last three). A similarexplanation would'apply to all these cases, a trace of optically activecontamination determining the development of an apparentlyholoaxial form. It may be necessary to investigate anew manycases where a low type of symmetry has been assigned to a crystalon the evidence of rare forms.The Interpretation of Rotation Photographs.The rotating crystal method of Rinne, Schiebold, and PbliLnyi isbecoming increasingly prominent as a.convenient and powerfulmethod of determining the space-group of a crystal. A mono.a 2. Phyaik, 1926, 39, 69; A,, 1086260 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRYchromatic beam of X-rays falls on a crystal which is rotated aboutan axis perpendicular to the beam and the reflexions are receivedon a photographic plate, or on a cylindrical film centred about theaxis of rotation. The crystal may be turned through a limited arc,or be completely rotated during the exposure. It is desirable touse a single crystal which is as perfect as possible, but very smallspecimens a fraction of a cubic mm. in volume suffice. The methodlends itself readily to a measurement of the cell-dimensions, and thelarge number of reflexions which are recorded provides amplematerial for the determination of the space-group.The principaldifficulty encountered is that of assigning indices to the spots onthe plate or film, and some care must be exercised in doing this inorder that trustworthy results may be obtained.Methods of analysing the photographs have been described byS~hiebold.~ Recently an exhaustive discussion of the geometricalproblem has been published by J. B. Bernal.4 This is the firstaccount in English which has appeared, and the care with whichthe author has prepared it will be widely appreciated. The ex-amination of crystals with all types of symmetry is described, andnumerous formulae are given.The array of formula appears somewhat forbidding a t a firstglance, but the nature of the problem must be borne in mind, Intreatises on crystallography considerable space must be devoted tothe description of methods of assigning a crystal to one of the32 classes and of measuring its axial ratios with the goniometer,although experience has led to a choice of the most direct methods.Here the geometrical problem is of the simplest, a goniometer beingused to measure the angles between faces by observing reflexions ofa light-signal.In X-ray analysis, a far more complex problempresents itself. Reflexion takes place a t all possible planes withinthe crystal, a t angles depending on the spacing of the planes andthe wave-length used. The very complicated record on plate orfilm contains enough information t o pake possible the choicebetween the 230 space-groups, and to give the' dimensions of theunit cell.It is therefore not surprising that the technique ofinvestigation is lengthy to describe and requires some apprentice-ship in practice. No doubt experience will indicate ways ofshortening the work, as has happened in the older and much simplerscience of goniometrical measurement. Several such ways aredescribed in Bernal's paper.The Dynamics of the Crystal Lattice.Some of the most interesting work on crystal structure which has2. Physik, 1924, 28, 355. Proc. Roy. Soc., 1926, [ A ] , 113, 117CRY STdLLOCtRAPHY. 261appeared in the last two or three years is concerned with the dynamicsof the crystal lattice.The pioneer in this field was Max Born, andhis classical treatment is surveyed in his monograph ‘‘ Atomtheoriedes festen Zustandes.” Its application is as yet confined to crystalstructures which may be regarded as composed of ions,* for prac-tically nothing is known about the forces between neutral atomsunited by bonds of other types. In the case of the crystals com-posed of ions, however, simple assumptions about the interatomicforces lead t o a highly interesting explanation of many crystalproperties. As this subject has not been dealt with recently inthese Reports, a brief summary may be of interest.In the absence of external forces distorting its structure, an ion issupposed to be isotropic or spherically symmetrical. When twoions are in proximity, the following forces exist :1.An attraction or repulsion between the ionic charges.2. An intrinsic repulsive force, dependent on the electronicconfigurations of the ions, which is inappreciable a t largedistances but rapidly rises to a high value as the ions approachone another.3. Forces due to the polarisation of the ions in each other’selectric fields.The electrostatic forces of the first type obey Coulomb’s law,and depend on the ionic charges and the distance between ioniccentres. The intrinsic repulsive forces act independently of ioniccharge, and are of the same nature as those which come into play,for instance, when two atoms of an inert gas rebound from eachother in a gaseous collision. Born attempted to give these forcesa formal expression by defining the potential energy of two ions a ta distance r apart as being b ] ~ .As is well known, Born deducedthe index n for the ions in crystals of the sodium chloride typefrom the volume-elasticities of the crystals, for the compressibilityof the crystal depends on the rate a t which the intrinsic repulsiveforce increases as the ions are forced together. Tho index n wasshown to have a valup of about 9. Values for b were assumed suchthat attractive and repulsive forces in the crystals balanced eachother. The heats of formation of the crystals from dispersed ionswere then calculated, work being done by the electrostatic forcesand against the repulsive forces as the ions came together. Bornhas devised an ingenious series of checks which show that thesetheoretical values are in good agreement with observation.* The esamination of the equilibrium conditions in crystalline argon (F.Simon and C.von Simson, 2. Physik, 1924, 25, 160; A . , 1924, ii, 686; J. E.Lennard-Jones and P. A. Taylor, PTOC. Roy. SOC., 1925, [ A ] , 100, 476; A.,1926, 11) is an exception t o the above statement262 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.A further step was taken by Born and W. Heisenberg in calcul-ating the effect of ionic polarisation. In a symmetrical crystal suchas that of sodium chloride, where every ion is surrounded by neigh-bouring ions, polarisation does not take place. If the salt is sub-limed, and the ions dispersed as molecules of sodium chloride, eachion i s strongly polarised by its partner, In any calculation of energychanges where ions are distorted, this polarisation must be takeninto account.The response of the ion to an external field is expressedby a constant K, the ion acquiring an electrical moment aE in a fieldof strength E. Born deduces values of a from optical constants.We may summariso by saying that the lattice theory in its simpleform assigns to the ions constants 2, n, b,-and CT. 2 measures theionic charge Be and a the " polarisability " of an ion. The constantsb and n determine the potential energy b / P due tto the intrinsicrepulsive forces between a given pair of ions. Ionic models definedby these constants can be used in an examination of the followingcrystalline properties :Energy of crystal lattice.Surface energy of crystal face.Dimensions and axial ratios of crystal lattice.Elastic constants and strength of crystal.Characteristic frequencies of the lattice.Characteristic vibrations of groups such as Coil, SO,".Piezo-electric effect.Relative stability of alternative crystalline forms.Refractive indices.Optical activity.Born's calculation 8 of the latent heats of sublimation of the alkalihalides is a good example of the application of these conceptions.The potential energy U which is lost when a system of dispersedions Na' and Cl' comes together to form a crystal can be calculated.Starting with the same system of dispersed ions, the energy V canbe calculated which is lost when the ions come together in pairs toform molecules, The heat of sublimation 8, when the solid cryst'alpasses into gaseous molecules, can be measured, and the threequantities should be connected by the equation U -8 = v.The following table shows the extent to which the relation is satisfied,all energies being expressed in kg.-cals.per g.-mol.U. 8. u - s. V . ( V d .NaF 222 56.6 16.5 161 (147)NaCl 182 44.3 138 139 (121)NaBr 172 38.6 133 133 (114)N d 158 37.0 121 126 (106)2. Phyaik, 1924, 23, 388; A , , 1824, ii, 434. 6 LOG. citCRYSThLLOGRAPHY. 263The quantities (V,) have been calculated without allowance forthe mutual polarisation of the ions in a molecule, which has beenmade in calculating V , and it will be seen that V is much closer toU - S than V,.Similar agreement is obtained for the remainderof the alkali halides.A further and fundamental advance has been made by J. E.Lennard-Jones,7 who has linked up the intrinsic repulsive forcesbetween ions with the corresponding forces between atoms of theinert gases of similar electronic configurations. Lennard- Jonesfinds, in the first place, that the equations of state, thermal con-ductivities, and viscosities of the inert gases can be explained byinverse-power laws of the form 'hm with suitable constants. Inorder to express the intrinsic force, n must be given values of 9, 10,or 11. The van der Waals attractive force is also important in thegaseous state and a corresponding term must be added, but i t is soweak in comparison with the electrostatic forces between ions incrystals that it may be neglected in this case.In order to connectthe forces between ions with those between inert-gas atoms, furtherassumptions must be made. For instance, the index .n for twoargon-like ions K and C1' is supposed to be the same as that forargon itself. The force constant 1, between two similar ions isgiven by the equation A1 = xn-l A,,,where x represents the ratio of thedimensions of the ion to those of the inert-gas atom with a constantx,,, Similar assumptions enable the force constants between unlikeions to be calculated. The ratios of the dimensions are based onconsiderations of refractivity (due originally to Wasastjerna) andatomic theory.Starting with kinetic-theory data, Lennard- Jones has calculatedthe length of unit-cell edge for crystals of the sodium chloride andcalcium oxide type, obtaining general agreement within 1 or 2% ofthe observed values.This is in itself a very striking achievement,and has recently been followed by a more elaborate analysis.Crystals of the calcite type referred to the customary axes arecharacterised by a rhombohedra1 angle which lies between 101" 56'(CaCO,) and 103" 25' (ZnCO,). The form of the crystalline structureis the result of eqiiilibrium between forces of attraction and repul-sion. W. L. Bragg and S. Chapman attempted to calculate therhombohedral angle theoretically by applying the principle ofvirtual work to small deformations of the structure, using a method7 Proc. ROY. SOC., 1925, [ A ] , 109, 684; A,, 1926, 11; J.E. Lennard-Jonesand (Miss) B. M. Dent, 8% 1926, [ A ] , 112, 231; A,, 888. These papersgive further references t o the work of these authors.8 Zbid., 1924, [ A ] , 106, 369; A . , 1925, ii, 92; compare Ann. Beport. 1924,21, 328264 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.which made it possible to obtain an approximate result withoutknowing the intrinsic repulsive forces. J. E. Lennard-Jones and(Miss) B. M. Dent,g and J. Topping and S. Chapman lo have extendedthe investigation and taken into account the repulsive forces. Avalue for the effective distance between carbon and oxygen atomsmust be assumed, since the nature of the bond is unknown. Lennard-Jones has shown that the sizes and shapes of the unit cell for all thecarbonates can be explained by a distance of 1.08 d. between thecarbon and oxygen of a CO, group.Conformations of equal poten-tial energy form contour lines in a graph where ordinate and abscissadefine the shape and size of the unit cell, and these contour linessurround a point of minimum potential energy which corresponds tothe conformation of equilibrium. A comparison for magnesiumand calcium carbonates is given below.MgCO,. CaCO,.(Calc.). (Obs.). (Calc.). (Obs.). -- -Rhombohedra1 angle ............ 102’ 24’ 103’ 21’ 102’ 18’ 101” 55’Distance between C-atoms ,. . . . . 4.66 4-61 4.96 4.96Thus the demity and shape of the calcite crystal hove been calculatedf r m measurements of thermal conductivity and viscosity of neon andargon.It is interesting to compare measurements of the CO, group madein very different ways.X-Ray measurements probably definethe distance of the inner electrons surrounding the oxygen nucleusfrom the carbon nucleus, and givevalues between 1.24A. and 1.34A.11The double refraction of calcite l2 is accounted for by a dis-tance of 1-27 d, from carbon to an isotropic polarisable 0” ion.The form of calcite is explained by Lennard-Jones on the assump-tion of a distance of 1.08 d., as defining the mean centre from whichthe electrostatic and repulsive forces act. Another line of attackis provided by the characteristic vibrations of the CO, group, butthis has so far met with little success. It is well known that ioiissuch as CO,” and SO,” are associated with definite frequencies inthe infra-red region characteristic of the groups in crystah and insolutions.H. Kornfeld,13 S. Chapman and A. E. Ludlsm,l4 andP. A. Taylor 15 have tried to account for the infra-red frequencies9 Proc. Roy. SOC., 1927, [ A ] , 113, 673, 690.10 Ibid., p. 668.11 (Sir) W. H. Bragg, PhiE. Trans., 1916, [ A ] , 215, 253; R. W. G. TTyokoff,l a W. L. Bragg, Proc. Roy. SOC., 1924, [ A ] , 106, 346: A , , 1925, ii, 97.1s 2. Phyeik, 1924, 26, 205; A., 1925, ii, 12.14 Phil, Mag., 1925, [vi], 50, 822; A., 1925, ii, 1026.1s Ibid., p. 1158; A., 1926, ii, 1115.Amer. J. Sci., 1920, 50, 317CRYSTALLOGRAPHY. 268due to oscillations of atoms in the CO, group, but the attempts haveled to paradoxical results, and it seems that we do not yet knowenough about the interatomic forces within the goup.Certain papers by F.Hund l6 are of great interest, The majorityof diatomic compounds crystallise in three typical forms. I n thecmium chloride type, ions of one kind occupy cube corners and thoseof the other kind cube centres, each ion having eight neighbours ofopposite sign. In the sodium chloride type the correspondingnumber is six, and in the zinc sulphide type four. Hund calculatesthe heat of formation of the three types for different inverse-powerlaws of repulsion in order to determine which is the most stableform. He shows that, ceteris paribus, when n>35 it is the c&umchloride type, when 35>n>6 it is the sodium chloride type, and forsmaller values of n the zinc sulphide type.Similar conclusions arereached as to the criteria which differentiate between the alternativeforms typified by CaF,, TiO,, Cu,O. The author further shows that thepolarisability is a highly important factor in determining the typeof crystal. Ions which are easily polarised are more likely to set as" molecular crystals " than as '' ionic crystals '' (Koordinations-gitter). If a is large, a symmetrical lattice is not the most stableform, since potential energy is further reduced by a one-sideddeformation of pairs of ions. As an intermediate stage betweensymmetrical crystals like sodium chloride, on the one hand, andgroups of molecules, on the other, there are the very interestinglayer crystals (Schichtengitter).In cadmium iodide and zirconiumsulphide, co-ordination takes place in sheets of symmetrically-placed positive and negative ions, but these sheets are separatedfrom each other as definitely as distinct molecules would be. Themolecule has indehite extension in two directions only, as comparedwith three in sodium chloride. Hund discusses the limiting valnesof a for which these layer-crystals become the type of greateststability.The results are suggestive as indications of the dependence ofcrystalline form on ionic properties, but it is doubtful whethersufficient is known about the intrinsic repulsive forces t o makepossible the application of so delicate a test, particularly when it isremembered that change of temperature (a factor not taken intoaccount in the calculations) often causes one form to change toanother.The most uncertain feature of all these examinations intocrystalline dynamics would appear to be the assumptions madeabout the intrinsic repulsive forces. The constants of an inverse-power law can be adjusted 80 as to explain lattice-spacings andl6 2. Physilc, 1925, 34, 833; Physikd. Z., 1925, 26, 682; A., 1925, ii,1132.I 286 m A L mPORTS ON THE PEOQRESS OB CHEMISTRY.crystal-compressibilities, but it does not follow that the same lawwill hold true over other ranges of interatomic distance. In calcula-tions of crystal energy such as those made by Born, this does notmatter greatly, for the work done against the repulsive forces onlyappears as a correction to the far greater work done by the electro-static forces, and the adjusted inverse-power law will give a fairapproximation to the most important part of the correction.In thecalculation of crystalline axial ratios, and of the relative stabilityof different types, it is important to know the law of force over a widerange of distance, and the assumption of a simple inverse-power lawmay lead to very wrong conclusions. Lennard- Jones’s deductionof the law from kinetic-theory data is less open to criticism becausea wide range is here involved. A more complete understanding ofthe intrinsic repulsive forces, however, appears to be most desirablefor further advance.G. Heckmann 17 has worked out the constants of the diatomiccrystals (NaCI, CsC1, and ZnS types), taking into account, not onlythe electrostatic and intrinsic repulsive forces, but also the forcesdue to polarisation of the ions.He shows what modifications areto be introduced into the usual formulae of Born for the dielectricconstants, piezo-electric constants, and wave-lengths of the “ Rest-strahlen.” The only elastic constants not affected by thenew theoryare Young’s modulus, the modulus of rigidity, and the coefficient ofcompressibility. The calculation of the surface energy of crystalsis important because of its bearing on the forces operative a t inter-faces in chemical action. Born l8 has made calculations of thequantity. J. E. Lennard-Jones and P. A. Taylor l9 recalculatedthe values with improved values for the constants determining therepulsive forces, and recently J. Biemiiller20 has considered theeffect of polarisation of the ions.He shows that this may lower thevalue of the surface energy by as much as 40% in extreme caseg,although the correction may in other cases be only a few units %.A paper by H. G. Grimm and A. Sommerfeld 21 raises an interestingpoint concerning the relation between chemical bonds and crystal-line structure. The authors ascribe the tetrahedral type of structure(ZnS, BeO, AUX) to a tendency on the part of the atoms towards acompleted four-electron shell, analogous to the well-known tendencytowards a %shell, 8-shell, and 18-shell. They point out thesimilarity between these structures and the diamond structure.To quote from a recent lecture by Sommerfeld “ Tetrahedral1’ 2.Phyaik, 1925, 31, 219; 2. Krist., 1925, 61, 260.18 Atomtheorie des featen Zustandes,” p. 743.10 Proc. Roy. Soc., 1925, [A], 109, 496; A., 1926, 11.20 2. Physik, 1926, 88, 759; A,, 1086. s1 Ibid., 36, 3 6 ; A., 660URYSTALLOGRAPEY. 267structure is only found in those binary compounds in which bothpartners are equidistant and a t most four places from a 4-shell;that is, from the elements C, Si, Qe, Sn, Pb.” Hund, as has beenmentioned above, ascribes the formation of these compounds to alow index n for the repulsive forces (“ soft ” atoms), but the possi-bility of its being due to a totally different type of bond must beborne in mind.The Intensity of X-Ray Reflexion.Progress towards a more complete understanding of the arrange-ment of the atoms in crystals is dependent on a knowledge of thelaws which govern X-ray diffraction.In seeking to extend thepowers of X-ray analysis, we are confronted with a problem whichis very like that of improving the resolving power of an opticalinstrument. When the possibilities of analysis were first realised,the most general application of the principles of interference sufficedfor the simple structures that were then attempted, but greaterprecision is needed when complex structures are under examination.In an X-ray examination, the waves scattered by the crystal unit indifferent directions are measured by an ionisation chamber orphotographic plate, and from their recorded strength an image ofthe scattering object is built up step by step.A resolving powerwhich will reveal a t once the coarse ‘‘ black and white ” of the rock-salt structure is powerless to deal with the faint half-tone shadeswhich outline the organic molecule.Recently P. P. EwaldZ2 directed attention to the erroneousassumptions often made in crystal analysis-in particular, to theassumption that intensity of reflexion is proportional to the squareof the “ structure factor.” A paper by W. L. Bragg, C. G. Darwin,and R. W. James 23 reviews the subject of ‘‘ Intensity of Reflexion.”The difficulties of precise analysis arise in the theoretical interpret-ation of the results of experiment, and not in the quantitativemeasurements, which can easily be made with sufficient accuracy.In the first place, it is necessary to know the laws which govern thescattering of X-rays in different directions by the individual atom.This will depend on the electronic configuration of the atom, forinterference between waves Scattered by the electrons in the atomwill take place.The scattering depends on the heat-motions of theatoms, which cause a diminution of scattering power as the temper-ature rises. It is probable that the Compton effect plays a largepart, for much of the radiation which is scattered is altered in wave-length and therefore is not included in the regularly-diffracted beam.Ia Phyeikat. Z., 1926, 26, 29.2s Phil. Mag., 1926, [vii], 1, 897; A., 663268 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.There is evidence, which will be discussed below, of a reversal ofphase when long waves are scattered by inner electrons belongingto atoms of high atomic weight.These factors all influence theamount of radiation scattered by an atom. The combination ofthe waves from these atoms to form a wave scattered by thestructural unit a8 a whole, and the further combination to form thewave reflected by a homogeneous fragment of crystal, all appear t obe governed by the classical laws of interference, and to lend them-selves to exact analysis. Difficulties arise again, however, when weattempt to apply a theory of intensity of reflexion to actual crystal-structures.The intensity of reflexion may be calculated on the suppositionthat a crystal is absolutely perfect, plane succeeding plane withmathematical regularity.Given the atomic arrangement, andhence the amount of radiation scattered by each unit of structure, aformula can be deduced for the total radiation reflected as a crystalis rotated through the reflecting position (this is a convenient wayof defining reflecting power). On the other hand, a crystal may beregarded as a mosaic of minute crystalline fragments, each perfectin itself but irregularly joined to its neighbours. On this assumption,a second formula for reflecting power can be deduced which is quitedifferent from the first. The two formula were f i s t worked out byDarwin in 1914, but the importance of the formula for the perfectcrystal was not properly realised until Ewald arrived at the sameformula independently many years afterwards.The reflectingpower calculated by the second formula may be 10-50 times asgreat as that for a perfect crystal, the apparent paradox of a greaterreflecting power for the imperfect crystal being explained by thelarger range of angles over which it reflects.The most important difference between the two formula lies intheir dependence on " Structure Factor." It is customary todenote by the symbol F the power of the structural unit to scatterX-rays in a given direction, expressed in terms of the radiationscattered by a single electron, so that F is a numerical ratio which isa dimensionless function of angle of scattering, wave-length, andatomic dimensions. The perfect crystal reflects X-rays completelyover a short range of angles which is proportional to F, so that Fappears in the first power in the expression for reflecting power.The imperfect crystal reflects a weaker beam over a wide range ofangle, the integrated reflexion being proportional to F z .It is, ofcourse, essential to know which formula should be used in any givencase. In general, it would appear that actual crystals tend to beof the mosaic type, but are too perfect for it to be possible to applythe " imperfect crystal ') formula without correction. The correcCRYSTALLOGRAPHY. 269tions take the form of allowances for “ primary extinction ” and‘‘ secondary extinction ” initiated by Darwin. A mathematicaldiscussion of the re0ecting power in intermediate cases betweenthe large perfect crystal and the small, homogeneous fragment isgiven by I.Waller.24The final results of quantitative analysis, when corrections forextinction have been successfully applied or have been renderedunnecessary by the use of the powder method, can be expressed a aseries of measurements of the scattering coefficient F. Thesevalues of F represent the data by the aid of which the image of thescattering unit must be formed. Two courses may be followed,and it is interesting to trace the relation between them. The usualcourse consists in making assumptions about the scattering powersof the individual atoms, and testing various models by comparingthe values of F calculated for them with those actually observed.Recently W.Duane 25 hag proposed a very simple way of invertingthis process. He shows that the values of F are the coefficients in aFourier series which represents the spatial distribution of scatteringmatter in the crystal structure. Series can be formulated whichgive the density of scattering matter a t a point, its radial distributionaround an atomic centre, or its distribution in sheets parallel to agiven crystal plane. R. J. Havighurst 26 has applied Duane’sformula to experimental measurements on rock-salt by Bragg,James, and Bosanquet, and has calculated the electron density alongcertain lines in the rock-salt crystal. The results are shown inFig. 1. The four curves represent the density plotted as ordinatein passing (1) along a cube edge through alternate atoms of chlorineand sodium, ( 2 ) along the cube diagonal, (3) along a face diagonalthrough atoms of chlorine alone, and (4) along a diagonal throughatoms of sodium alone.The directness of the method is a veryattractive feature. No assumptions about atomic positions orscattering power are made, the experimental results being directlyapplied to a determination of the distribution of scattering matter,which may in its turn be interpreted as due to the atomic arrange-ment.The new method has its limitations. X-Ray analysis measuresthe coefficients F of the terms of the Fourier series, but not theirphases, which must be deduced from considerations of symmetryand of probable crystalline arrangement. Further, the number ofterms in the series which can be measured is limited by the numberof spectra yielded by the crystal, and the series often convergesAnn.Physik, 1926, 79, 261.2 5 PTOC. Nat. Acod. Sci., 1926, 11, 489.* 6 Ibid., p. 502; 1926,12, 380; A., 780270 ANNU~L REPORTS ON THE PROQRESS OB CHEMISTRY.slowly. The absence of higher terms from the series when summedmay give a very erroneous idea of electron distribution, just as amicroscope of low reaoIving power may add false detail to an image.Nevertheless, the method has very great possibilities and will noFIGURE Idoubt be widely used in future analysis. Its application to thecomplex crystal beryl 2' and to the mercurous halides shows howit can be used for direct determination of parameters. Duane'swork is based on a quantum theory of diffraction, but A.H.2' W. L. Bragg and J. West, Pmc. Roy. SOC., 1926, [ A ] , 111, 691; A., 889.R. J. Havighurst, J . Amer. Chem. rSoc., 1926, 48, 2113; A., 996CRYSTALLOGRAPHY, 27 1Compton 29 has shown that the classical theory of diffraction leadeto an exactly similar expression. Since the Fourier analysis yields theaverage distribution of scattering matter directly, it would appear tobe the best way of detecting asymmetry of the atom in the crystal-line structure. It is one of the most interesting additions to thetechnique Qf X-ray analysis of recent years.The temperature factor has been the subject of a theoretical studyby I. Wt~ller.~Q Debye originally proposed an expression e-M forthe temperature factor of a cubic crystal, in which6h2 sin2€l cp(x)yk0' A 2 - ' x M =Characteristic temperature 0 of crystalActual temperature Twhere 5 = ____ ___ - __ ..--aWaller has deduced that the temperature factor should be e-2K, note-do. R. W. James 31 has measured the factor for rock-salt betweentemperatures of 90" and 900" K. He has proved that llil varieswith sin28/A2 to a high degree of accuracy by using different facesas reflectors, and has shown that Waller's formula (not Debye's)is closely obeyed between 90" and 600" K. Beyond this temperature,the intensity of reflexion falls away more quickly than is indiciitedby theory, presumably owing to a change in the elastic constants ofthe crystal. These measurements of temperature factor are interest-ing because they yield a direct estimate of the amplitude of vibrationof the atoms in ehe crystal.The F-curves of individual atoms can be obtained from the studyof simple crystals, and trustworthy measurements are accumulating.R.W. James and J. T. Randall32 have measured the scatteringpowers of calcium and fluorine in calcium fluoride. R. J. Havig-hurst 33 has published curves for calcium, fluorine, lithium, andsodium, working with lithium, sodium, and calcium fluorides.A. Claassen34 has obtained values for iron and oxygen in Fe,O,.Havighurst's measurements are especially interesting because theywere made with crystalline powders, so that secondary extinctionwas absent. By grinding the powder to very fine dimensions,Havighurst tried to avoid primary extinction. His results with thefinest powders are in close agreement with each other and with those2.Phy8ik, 1923, 17, 398; " Theoretische Studion zuc Interferenz u.Dispersionstheorie der Rdntgenstrahlen," Uppsals Univeraiteta Areskrift,1925..29 Physical Rev., 1926, 27, 510.31 Proc. Manchester Lit. Phil, SOC., 1926, 71.3a Phil. Mag., 1926, [vii], 1, 1202; A., 663.ss Proc. Nat. Acad. Sci., 1926, 12, 380; A,. 780.Proc. Physical SOC., 1926, 38, 482; A,, 1072272 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of Bragg, James, and Bosanquet for large rock-salt crystals aftermaking allowance for secondary extinction. An accurate determin-ation of the F-curve is interesting, because i t gives evidence as tothe distribution of electrons in the atom.Bragg, James, andBosanquet used a ‘‘ trial and error ” method of fmding electronicdistribution which explained the F-curves. R. J. Havighurst 35and A. K. Compton 36 have applied the Fourier analysis to the sameproblem. The electron-distribution curves of Compton are similarto those obtained by Bragg, James, and Bosanquet and by Havig-hurst from the same data, but show more detail. The radial dis-tribution falls to zero at about 1-1 A. from the centre of the sodiumion, and 2.0 A. from the centre of the chlorine ion. Compton findsinteresting peaks in the radial distribution curves which he attri-butes to the orbital extremities of different electronic groups in thecrystal.In deducing electronic configurations, however, the possibleinfluence of the Compton effect must be borne in mind, for it mayvitiate conclusions drawn by using the classical laws of interference.H.Kallmann and H. Mark 37 examined the possible interference ofthe modified radiation, which Compton has shown to be scatteredwith a change of wave-length and explained by a quantum hypothesis.E. J. Williams 38 has discussed the influence of the Compton effecton the F-curve. It is assumed (1) that only the unmodified radiationcontributes to reflexion, and (2) that Compton’s criterion for modi-fication (as developed by Jauncey) holds, vizq, that if the deflexionof the sc&tered quantum gives spfficient energy to the scatteringelectron to eject i t from the atom, the ray is modified. Otherwisethe quantum is scattered without change of wave-length. Williamsapplies this criterion to atomic models for calcium and fluorinecalculated by Hartree.The F-curve, allowing for thc Comptoneffect, falls more steeply than the classical curve due to Hartree,and is smoother in outline. I n fact, i t approximates much moreclosely to the observed F-curve. The work of Williams and Jaunceymay lead to a satisfactory agreement between theory and experiment,which has hitherto been unobtainable.A fundamental point is raised by H. Mark and L. S ~ i l a r d . ~ ~Rubidium bromide (111) planes consist of alternate sheets ofrubidium and bromine atoms. These atoms are SO nearly alike inscattering power that (111) and (333) reflexions, for which the atomsare in opposition, are in general too weak to be observed, If,35 PTOC.Nat. Acad. Bci., 1925, 11, 506.37 2. Physilc, 1926, 36, 120; A., 551.8 8 Phil. Mug., 1926, [vii], 2, 657; A,, 988.s9 2. Physik, 1925, 33, 688,3 6 LOC. citCRYSTALLOGRAPHY. 273however, a wave-length between the Rb and Br R-absorption edgesis used, the reflexions appear (Sr K,-radiation fulfils this condition).The K-electrons alone can be concerned in the effect, and thepositive result obtained by Mark and Szilard means that the scatteredwaves from these electrons in rubidium and bromine differ inamplitude or phase. A difference in phase would correspond to thedifference in phase on the classical theory of the response of anoscillator to forced vibrations of higher or lower frequency.It maybe necessary t o give a negative sign to the contributions to theF-curve from the K-electrons of atoms of high atomic weight.The preceding discussions deal largely with atomic structure,but the points which are raised are of vital importance to crystalanalysis. Refinement of technique is essential in order that X-raymethods may be used to the full in examining structure.Inorganic Crystals.Among the more interesting of the inorganic structures recentlyanalysed are potassium and sodium trinitrideam Sodium trinitride,NaN,, is rhombohedra1 with one molecule to the unit cell. Thesodium atoms lie a t the corners of the unit rhombohedron (a = 5.481 B., u = 38" 43'). The three nitrogen atoms are collinear and liealong the diagonal of the rhomb, one atom a t the centre of the cell,the others symmetrically on either side of it a t a distance of 1.17 A.Potassium trinitride, KN,, forms tetragonal crystals, with fourmolecules to the unit cell (a = 6,094 A,, c = 7.056 A).The N,group has the same form and dimensions as in sodium trinitride,but the lines of the groups are perpendicular to the tetragonal axesand a t an angle of 45" to the cell edges. The difference in structurebetween the sodium and potassium salts is in all probability due tothe much greater size of th6 potassium ion. Many similar casesoccur ; e.g., sodium nitrate has a calcite structure whilst potassiumnitrate is orthorhombic and similar to aragonite.We may compare with the N, group the structures of solid nitrousoxide and solid carbon dioxide.41 These compounds form cubiccrystals with symmetry of the pyrites type.The groups N,O and CO,are well marked and are linear, the atomic centres lying on the fournon-intersecting trigonal axes. In nitrous oxide, the distancefrom nitrogen to oxygen is given as 1.15 d., which indicates a close' 0 S. B. Hendricks and L. Pauling, J. Amer. Chem. Soc., 1925, 47, 2904;A,, 1926, 113.41 J. de Smedt and w. H. M. Keesom, proc. K. AEad. Wetenoch. Amsterdam,1924, 27, 839; A., 1925, ii, 484; H. Mark and C. Pohland, 2. Krbt., 1925,61, 293; J. C. McClennan and J. 0. Wilhelm, Tr~cne. Roy. SOC, Canada,1926, [iii], 19, 111, 51; A., 1926, 13274similarity between the groups N,O and N3. The Iength of the cubeedge is 5.74 A.For carbon dioxide Mark and Pohland give 5.62 A.for the cube edge, and de Smedt and Keesom agree with this.McClennan and Wilhelm give 5.74 A., but this is not in goodagreement with the accepted value of the density of solid carbondioxide at the temperature of liquid air. The three estimates ofthe distance C-0 differ greatly, for Mark and Pohland give 1.59 8.,McClennan and Wilhelm 1.25 A., and de Smedt and Keesom1.05 A. Evidently further investigation is needed. It is interest-ing to note that the distance N-N is of the same order as thedistance N-0 in the NO,' group of sodium nitrate.Further evidence of the existence of definite complex ionic groupshaving a form which is permanent from compound to compound isgiven by the analysis of several sulphates.Lithium potassiumsulphate 42 (hexagonal), barium sulphate, strontium sulphate, leadsulphate,& and anhydrite, the anhydrous form of calcium sulphate,44have now been analysed. In all these compounds tbe SO, grouphas approximately the same size and form. The four oxygenatoms are arranged with their centres a t the corners of a nearlyregular tetrahedron whose edge is about 2.5 A. and at whose centrethe sulphur atom lies. The space occupied by the group in thedifferent crystals can be accounted for by describing about the centresof the oxygen atoms spheres of radius 1.35 A. The group can thusbe considered as made up of four 0-2 ions held together strongly bythe S+Gion a t its centre. The distance S-0 is about 1.55A.Barium, strontium, and lead sulphates are members of an interestingisomorphous series including among other compounds the per-chlorates and permanganates of potassium, rubidium, caesium, andammonium.Measurements on potassium perchlorate and perman-ganate 45 show that the structures of these compounds are essentiallysimilar to those of the sulphates and indicate that the XO, group hasvery much the same dimensions in all of them and is the determiningfactor in deciding the structure. The crystals of the barytes groupare orthorhombic and the structure belongs to the space groupVj:. Each metal ion is surrounded by twelve nearly equidistantoxygen neighbours belonging to the SO, groups.Anhydrite, although also orthorhombic, belongs to the group V;:ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.4: A.J. Bradley, Phil. Mag., 1926, [vi], 49, 1225; A , , 1925, ii, 638; com-pare Ann. Report, 1925, 22, 253.4s R. W. James and W. A. Wood, Proc. Roy. Soc., 1925, [ A ] , 109, 595;A., 1926, 13.44 J. A. Wmastjerns, SOC. Scient. Fennica, 1925, 2, 26; Phil. Mag., 1926,[vii], 2, 992; A., 1195; E. C. S. Dickson and W. Binks, kbid., p, 114; A+,781.d6 R. W. Jamea and W. A. Wood, Zoc. citCRYSTALLOGRAPHY a 27 5and has a structure quite different from that of barium sulphateThe crystal hm two reflexion planes of symmetry on the intersectionof which the sulphur atoms lie. The oxygen atoms form a tetra-hedral group about the sulphur and lie in pairs on the symmetryplanes. The calcium atoms lie on the intersections of the planes andalternate with the SO4 groups.We have here an interesting caseof two compounds, chemically closely akin, forming very differentcrystals, while compounds as distinct chemically as barium sulphateand potassium perchlorate form very similar crystals. There seemsto be little doubt that the size of the ionic domain of the metal ion isthe determining factor. K and Ba" are similar in size, but Ca"is considerably smaller, so that twelve oxygen ions can no longerpack round it.The idea of a desnite atomic or ionic domain must of course beapplied with proper caution, but so much evidence that an approxi-mately constant volume is occupied by an ion of a given type fromcrystal to crystal is now available that i t would be foolish to ignoreit altogether.By its aid it has been possible to attack some of themore complex inorganic structures of lower symmetry, where theatoms are fixed by a number of parameters. Most of these com-pounds contain oxygen, and a knowledge of the fact that the centresof two oxygen atoms do not as a rule approach closer to one anotherthan about 2.7 A., unless held by very strong forces, as in some of thecomplex ions, is of great use in selecting structures which are probablephysically from those which are possible geometrically.Good examples of this may be found in the analyses of a number ofthe gem-stones, which consist as a rule of oxygen in combinationwith ions such as Be",Al"',Si"",E'e"', and Mg", all of whichare smallcompared with the oxygen.The latter, therefore, appear frequentlyto be nearly close-packed either in cubic or hexagonal array, whilstthe smaller ions are able to pack in the holes between the oxygenaholding them together, but slightly distorting or expanding theclose-packed structure and lowering its symmetry. Compoundswhose dimensions indicate that they are essentially hexagonallyclose-packed oxygen ions are aluminium oxide,46 beryllium oxide,47chrysoberyl, BeAl,0,,48 and 0livine.4~ The first two of these4 0 W. L. Bragg, Proc. Roy. Soc., 1924, [A], 106, 346; A . , 1925, ii, 92;S. B. Hendricka and L. Pauling, J. Amer. Chem. SOC., 1925, 47, 781; A , ,1925, ii, 368.p 7 L. W . McKeehan, Proc. Nat. Acad. Sci., 1922, 8, 270; A . , 1922, ii, 766;G. Aminoff, 2.Kriet., 1926, 62, 113; A., 1926, 227; W. Zachariasen, 2.physikal. Chem., 1926, 119, 201; A., 662.'e. W. L. Bragg and G. B. Brown, Proc. Roy. Boo., 1926, [A], 110, 34; A.,227.La Idem, 2. Knkt., 1926, 68, 638; A,, 996276 ANNUAL REPORTS ON THE PROGRESS OB CHEMISTRY.crystals are hexagonal; the others are orthorhombic. I n othercases, a local close-packing of oxygen ions occurs whilst there areconsiderable spaces elsewhere. An example of such a structure isberyl, Be3A.12Si,0,,.~ In this crystal, the silicon and oxygen atomsform rings of the composition Si,O,,, built up by SiO, groups, eachjoined to its neighbour on either side by an oxygen atom held incommon. The distance 0-0 in an SiO, group is 2-54if. Thiscloser grouping may be compared with that in the group SO,.The crystalline forms of silica, viz., quartz,61 crist~balite,~~ andtridymite,s3 also show the grouping of oxygen atoms in tetrahedraabout the silicon atoms.The recent analysis of tridymite by Gibbsextends the very striking relationship between the many modific-ations of silica. The distance 0-0 in the SiO, groups of thesecrystals is about 2.52 A. Garnet, Ca,AI,Si,O,,, has been analysedby G. Menzer,a and here again the distances between the oxygenatoms are everywhere about 2.7 8.In a series of papers, H. Ott 55 has investigated the structures ofthe four modifications of carborundum, Sic. In all these structures,the carbon atoms are surrounded tetrahedrally by four silicon atomsand vice versa, the distance from carbon to silicon being 1.008.There are two simple ways of making an arrangement of this type-one, analogous to the structure of diamond, typified by the cubiczinc-blende lattice, the other typified by the hexagonal zinc sulphide,wurtzite.The so-called amorphous modification of carborundumhas the simple zinc-blende lattice ; the other modifications, however,are trigonal or hexagonal and show remarkable alternations of thezinc-blende and wurtzite lattices along the axes. Modification I1is hexagonal, a = 3.09 A., c = 15.17 A., with 6 molecules to the cell.Modification I is trigonal, but expressed in hexagonal terms the unitcell has 15 molecules, a = 3-09 8., c = 37.9 if. Modification I11 isdihexagonal, a = 3.09 A., c = 10.09 8. No other simple com-pounds are known in whicd the dimensions of the elementary cellare so large, It might be expected that, with the two types ofarrangement possible, twinning would take place very readily, butthat the twinning should be so regular and on the small scale of theelementary cell is very remarkable.m W.L. Bragg and J. West, Proc. Roy. Soc., 1926, [ A ] , 111, 691; A.,(Sir) W. H. Bmgg and R. E. Gibbs, aid., 1926, [ A ] , 109, 405; A., 1926,889.13.6* R. W. G. Wyckoff, Amer. J. Sci., 1925, 9, 448; A . , 1926, ii, 638.65 R. E. Gibbs, Proc. Roy. Xoc., 1926, [ A ] , 113, 361. '' 2. KTkt., 1926, 03, 157.5 6 Ibid., 1925, 61, 616; 02, 201; 63, 1 ; A,, 1926, 562CRYSTALLOGRAPHY. 27 7V. M. Goldschmidt 55a has prepared a most interesting and valu-able summary of present knowledge about the structure of thesimple inorganic compounds.I n many cases, where a few membersonly of a series of crystals had been analysed, he and his collaboratorshave completed the examination of the series. This extensive surveyhas revealed interesting relationships between the structures of thecompounds. The relationships are interpreted by considering twoproperties of the ions which build up two crystals as being of primeimportance, their size and the extent to which they can be polarised.A broad treatment along these lines introduces law and order intothe mass of information about inorganic structure, and it is strikingto see what an immense number of compounds have structureswhich approximate to certain simple types.The summary coversso wide a field that it is difficult to select any of the special pointsin it for mention; a study of it should be made by anyone who isinterested in chemical crystallography.Interesting work on the structure of metals and alloys has beendone during the year. The diacussion of this is reserved for a futureReport, both on account of lack of space and because the researchesin general have not reached that stage of completion which isdesirable for a Report.Organic Crystals.Cellulose.-Readers of last year’s Annual Report who are interestedin the X-ray investigation of cellulose will find it profitable to con-sult a recent communication by R. 0. H e r ~ o g . ~ ~ This is a dis-cussion of all the experimental data that are as yet available, andis the most complete account in English that has appeared hitherto.Rubber.-In the same connexion must be mentioned also theimportant work of E.A. Hauser and H. Mark 57 on the structureof rubber. These authors have investigated in detail thephenomenon, discovered by J. R. Katz, 5a that rubber when stretcheddevelops a strongly-marked crystalline structure, which disappearson heating, or on releasing the tension. In the unstretched state,the structure is apparently amorphous, but on extension rubbergives rise to an X-ray photograph similar to that usually obtainedfrom asbestos, Le., it develops a structure made up of crystalliteswhich are all oriented so that a certain crystallographic axis always56n I‘ Geochemische Verteilungsgesetze der Elemente VII.Die Gesetze derKrystallochemie,” Norake Vidensk4p-Akademi I, Mat. Nat. Kl., 1926, No, 2.sB J . Phyaical Chem., 1926, 30, 467; A., 677.6 7 Koll. Chem. Beih., 1926, 23, 6 4 ; A., 1098; Ambronn Festschrift, 1926,6 8 h’olloid-Z., 1925, 36, 300; 37, 19; A., 1925, ii, 887, 969.63278 ANMTAL REPORTS ON THE PROQRESS OF CHEMISTRY.points along the direction of tension.5B As the extension is in-creased, the positions of the spots on the photograph remain un-altered, but their intensity increases to a degree nearly proportionalt o the extension, whilst the intensity of the ‘ r amorphous ” ringdecreases in a similar manner. A careful examination of thephotographs has furthermore shown that the amount of crystallinephase is increased, not by the growth of old crystallites, but by thecontinuous formation of new crystallites.A possible crystal unithas been deduced which contains four C,H,-groups. This im-portant result shows that the molecular weight is relatively small-an observation similar to the one already made on the crystalliteaof cellulose. In the papers mentioned, the physical properties ofrubber are discussed in connexion with these striking results.Long-chain Compounds.-X-Ray investigation of these compoundscontinues to yield new and interesting results. The latest paper 60on the subject deals with a phenomenon previoudy observed byMiiller in the hydrocarbons, viz., the existence of two or morecrystal forms. Piper, Malkin, and Austin have examined thispolymorphism in greater detail.They have observed three typesof X-ray spectra for the higher fatty acids, besides recording variousirregularities in spacing associated apparently with different modesof preparation and mounting. The authors do not appear to bejustified in interpreting their observations as indicating the existenceof a t least two forms of chain. Until the space-group and completestructure of the crystals have been worked out, nothing further canbe concluded than that they are capable of existing in polymorphousforms, as happens in the case of so many other crystals. An ex-ceedingly interesting point deserves mention, viz ., that mixtures ofstearic and palmitic acids show only one long spacing which iscontinuously variable with the composition of the mixtures, afterthe manner of ordinary isomorphous mixtures, even though thereis more than 4 A. difference between the normal lengths of the twochains.i-Erythrito1.-This compound has been shown 61 to be based onthe space-group C$ of the tetragonal-bipyramidal class. Thebody- centred cell contains eight molecules, each being symmetricalabout either a centre or a dyad axis of symmetry. But, in agree-ment with the conclusions of stereochemistry, the crystal evidenceis strongly in favour of a centro-symmetrical molecule.Tervalent Metallic Acetyhcetone-s.62-From X-ray examination of60 Compare Ann. Report, 1925, 22, 247.60 S. H. Piper, T. Malkin, and H. E. Austin, J., 1926, 2310; A., 1083.61 W. G. Burgers, Phil. Mag., 1926, [vii], 1, 289; A., 339.62 W. T. Astbury, PWC. Roy. SOC., 1926, [A], 112, 448; A., 996CRYSTALLOGRAPHY. 279a series of ten of these compounds, the nature of the remarkableisotrimorphism which they collectively exhibit has been elucidated.The a-(monoclinic) form, space-group C&, and the p-(orthorhombic)form, space-group Czb, each contain four chemical molecules, whilstthe y-( orthorhombic) form, space-group C:", contains sixteenmolecules, and must therefore be assumed to be built up of associatedgroups of four molecules each. The molecular distribution in allthree cases is similar, the difference lying in the respective molecularorientations. Although the molecules in all three caseB are crystallo-graphically asymmetric, there is little doubt that the atomic con-figuration known to stereochemistry holds in all three structures.All three forms are racemates.Basic Beryllium Acetate and its Hornol~gues.~~-Laue photographsof basic beryllium acetate have shown that its space-group is TA,and that, consequently, its molecular symmetry is only twelvefold,namely, four triad axes and three dyad axes. Even this lower typeof symmetry is more than would be expected unless we neglect thehydrogens of the methyl groups. Their effect on the crystal sym-metry must be inappreciable, otherwise i t would be difficult toexplain the dyad axes which the methyl groups undoubtedly possess.A similar moIecular distribution prevails in the basic pivalate, butin this compound (monoclinic domatic, space-group Ct) the sub-stituted methyl groups assert themselves and the molecular sym-metry is completely lost. Certain observations have been made alsoon the basic butyrates which point to asymmetric molecules, as isto be expected.The writer wishes to acknowledge his indebtedness t o Dr. J. E.Lennard-Jones, Dr. A. Westgren, Mi. W. T. Astbury, and Mr. R. W.James for assistance in the preparation of the Report.pi. L. BRAGQ.63 G. T. Morgan and W. T. Astbury, ibid., p, 441; A,, 995

ISSN:0365-6217    

DOI:10.1039/AR9262300257

出版商:RSC    

年代:1926

数据来源: RSC

摘要:

SUB- ATOMIC PHENOMENA AND RADIOACTIVITY.THE two years (1925-6) under review may possibly be consideredsomewhat disappointing as far as actual advance in nuclear physicsis concerned. In radioactivity itself, the most interesting problems,such as the mechanism of disintegration and the origin of actinium,still appear too difficult of direct access, although the work ofanalysis of p-ray spectra and the more accurate fixing of constants,so necessary in the preparation for further advance, is well main-tained. In two other important fields, the disintegration of nucleiby the impact of a-rays, and the measurements of nuclear massesby the mass-spectrograph, there has now come the inevitable periodof quiescence awaiting the development of new weapons, It thushappens that the period is most remarkable for an unprecedentedactivity in alchemy, if by such term we designate attempts a ttransmutation by operations ludicrously inadequate, to all appear-ance, for such a tremendous task. Fortunately, the epidemicseems on the wane.Although experiments, even the wildest,should never be discouraged, progress is retarded rather thanadvanced by adopting the least likely, although most sensational,explanation of results. One cannot help feeling that the workexpended in the futile attempts to make gold from mercury mighthave been much more profitably used to develop our knowledgeof the structure of atoms along more rational, although more prosaic,lines.Mass-spectra and Isotopes.The last of a series of papers 1 on results obtained with the originalmass-spectrograph appeared early in the period under review.Itcontains a complete list of isotopes thus far identified 2 and indicatessome of the difficulties in the way of dealing with the remainingelements. Since then fresh discoveries in connexion with isotopicconstitution are recorded in the case of two elements only :Mercury.-The original mass-spectrograph was incapable ofresolving the lines of isotopes of this element which differed by oneunit, so that the mass-numbers included in the unresolved bandF. W. Aston, Phil. Bug., 1925, [vi], 40, 1191; A., 1925, ii, 618.* Compare Ann. Report, 1924, 21, 240.28SUB-ATOMIC PHENOMENA AND RADIOACTIVITY 6 281were uncertain. By means of a new and more powerful instrument,these lines have now been clearly resolved and the constitutionhas been more definitely settled.3 The mass-numbers and corre-sponding approximate intensities of the isotopes of mercury are198(4), 199(5), 200(7), 201(3), 202(10), and 204(2), which are in goodaccordance with the atomic weight.If other isotopes exist, theymust be present in very small proportion.SuZphur.--In the early work with this element, its principalconstituent was shown to be of mass-number 32, and since, withthe resolving power then available, this could not be distinguishedfrom 32.06, the atomic weight, it was considered safer to ascribethe fainter satellite lines 33 and 34 to hydrides. Under the increasedresolving power of the new instrument, this view is untenable,and it is shown that the latter are really isotope^.^ This was con-firmed by a negative mass-spectrum, obtained by prolonged exposurewith both fields reversed, which showed all three lines.S34 is aboutthree times mqre abundant than P3, the two together amountingto about 3% of the whole.By means of a mass-spectrograph of special design, for whichan accuracy of 0.03y0 is claimed, J. L. Costa 5 has compared themasses of some of the lighter atoms by the method of bracketing.Assuming a standard value of 4*0000 for helium, he obtains for thehydrogen atom a value 1.0079, for the lighter lithium isotope 6.009,and for the carbon atom 12.000. value of 14-008 for thenitrogen atom, the heavier isotope of lithium has a mass between7-010 and 7.013.G. Stettcr 6' has combined the principle of themass-spectrograph with the scintillation method to determine themass of the high-speed particles-protons-emitted by paraffin whenbombarded with a-particles. Using the a-particles themselves asstandard, he obtains the expected result corresponding with thetheoretical weight of the hydrogen nucleus.A discovery which may prove of great importance in the futurestudy of mass-rays is that made by C. H. Kunsman that a pre-viously fused mixture of iron oxide and a small quantity of an oxideof an alkali or alkaline-earth metal when used as a hot anodebecomes a constant and abundant emitter of singly-charged positiveions of the corresponding metal. Positive ion currents of the orderof lo4 amp./cm.2 are obtained in a vacuum of 10-o mme8 TheAssumingF.W. Aston, Nature, 1925, 116, 208; A., 1925, ii, 833.4 I d e m , ibid., 1926, 117, 893; A., 771.Ann. Physique, 1925, [XI, 4, 425; A,, 1925, ii, 1021.2. Physik, 1925, 34, 158; A., 1925, ii, 1021.7 Science, 1925, 62, 269; A., 218.8 H. A. Barton, G. P. Harnwell, and C. H. Kunsman, Physical Rez*.,)_1926,ii], 27, 739; A., 769282 A ~ A L REPORTS ON THE PROGRESS OF CHEMISTRY.emission of positive ions from heated salts has also been studiedby G. C. Schmidt and H. E. Ives.loBy measuring the current carried by the positive ions emitted bylithium, the relative proportions of its two isotopes have beendetermined.11 When proper corrections had been applied, Li7 waBfound to be 14 times more abundant than LiS, in good agreementwith the accepted atomic weight, 6.94.A method of treatmentof photographic plates by partial removal of the gelatin is described12by which their sensitivity to the impact of mass-rays is largelyincreased. Unfortunately, the method is both difficult and uncer-tain. Tho keeping properties of the product are also very poor.These plates were, however, essential to the identification of theisotopes of the less favourable elements.A number of papers dealing with the structure of atoms andisotopes have appeared: H. Stintzing13 elaborates a system inwhich all the atomic masses, including those of isotopes, can berepresented by a scheme of tetrahedra; R. Reinicke 14 modifiesand extends this scheme; H. Nagaoka l6 considers the relationbetween atomic weight and atomic number, and makes the startlingsuggestion 16 that within the nucleus of the atom two protons maycombine to produce a helium nucleus, the additional two units ofmass being produced by the energy absorbed in the process.Otherspeculative papers on the periodic table are those of D. de Barros,17T. Hori,l* E. W. Washburn,lg and S. Schtschukarev.20Art$cial and Natural Separation of Isotopes.Few attempts a t artificial separation are t o be recorded, noneof them yielding positive results. J. E. G. Pilley21 gives a fullaccount of his attempts to separate the isotopes of chlorine andof magnesium by ionic migration in agar gel under a potential of300 volts, and suggests possible causes of failure.H. Brennen 22S Ann. Phyaik, 1926, [iv], 80, 588: A., 877.10 J . Franklin Inst., 1926, 201, 47; A., 218.11 M. Morend, Compl. rend., 1926, 182, 460; A,, 331.1% F. W. Aston, Proc. Can& Phil. SOC., 1925, 22, 548; A . , 1925, ii, 706.14 Ibid., 1926, 37, 210; A., 773.16 Proc. Imp. Acad. Tokyo, 1926, 2, 112; A., 1075.18 Ibid., p. 204; A,, 1076.1 7 Compt. rend., 1925, 181, 719; A,, 1926, 7.18 Mem. Call. Sci. KyZ6, 1926, 9, 371; A., 879.1s J. Amer. Chem. SOC., 1926, 48, 2351; A., 1075.20 Neue Anachauungen in der Chemie, 1924, 9, 61 ; A., 1925, ii, 462.21 Phil. Mag., 1925, [vi], 49, 889; A,, 1925, ii, 462.38 Cow@. rend., 1925, 180, 282; A., 1925, ii, 174; Ann. Chim., 1925, [XI,13 2. Ph?/&k, 1925,34, 686; A,, 1926,7.4, 127; A., 1925, ii, 1109BOB-ATOMIU PHENOMENA AND RADIOACTIVITY. 283has investigated the claim= that the isotopes of lead could beseparated by means of the Grignard reaction, and finds no traoeof such effect, T.W. Richards24 also reports the same result,and, in addition, a failure to separate the isotopes of lead by irre-versible evaporation. Ammonium bromide has been subjected toprolonged fractional crystallisation 25 and the atomic weights ofthe bromine in the final head and tailfractions have been determined.No separation was observed.In regard to natural separation indicated by inconstancy of atomicweight, chlorine has been further examined by Mlle. E. Gleditsch,2sW. D. Harkins and S. B. Stone,27 and A. W. Menzies,2s but althoughvery wide ranges of terrestrial and meteoric sources were used,no variation was detected.The atomic weight of silicon fromvarious sources has been determined 29 with extreme variatioiis28-058 and 28.063. Furthermore, the densities of samples of silicontetrachloride made from similar sources have been measured by aflotation method of extraordinary deli~acy.~O Here the calculatedapparent variation of atomic weight for silicon was not greaterthan 0.005 of a unit.On the other hand, Briscoe 31 reports a definite variation in theatomic weight of boron from three different sources. Determin-ations by means of boron trichloride and also density measurementsgive practically identical results, viz., California, 10.847 ; Tuscany,104323 ; and Asia Minor, 10-818. A valuable confirmation of thisresult is afforded by the fact that differences of the same orderhave been found by 0.Honigschmid (private communication),who gives 10.818, 10,825, 10.840 as the atomic weights yielded bythree different samples of boron of unknown origin. This is thefirst well-substantiated variation of an element, not of radioactiveorigin, in natural atomic weight. It is interesting to note that ifany action leading to separation takes place a t all, boron, of allT. Dillon, R. Clarke, and V. M. Hinchy, Sci. Proc. Royal Dublin SOD., 1922,17, 53; A., 1922, ii, 710.24 T. W. Richards, H. S. King, and L. P. Hall, J. Amer. Chem. Soc., 1926,48, 1530; A., 771.2 5 P. L. Robinson and H. V. A. Briscoe, J., 1925, 127, 138; A., 1925, ii,620.J .Chirn. physique, 1924, 21, 456; A., 1925, ii, 174.2' Proc. Nat. Awd. Sci., 1925, 11, 643; A,, 1925, ii, 1108; J . Amer. Chem.SOC., 1926, 48, 938; A,, 553.I8 Nature, 1925, 116, 643; A., 1925, ii, 1109.2o H. V. A. Briscoe and P. L. Robinson, ibid., 1926,117,377; A., 331.*O P. L. Robinson and H. 0. Smith, J., 1926, 1262; A,, 771.a1 H. V. A. Brisooe and P. L. Robinson, dbid., 1925, 127, 696; A., 1925,ii, 346; H. V. A. Briscoe, P. L. Robinson, end a. E. Stephenson, {bid., 1926,70; A.,219284 ANNU& REPORTS ON THE PROGRESS OF CHEMISTRY.elements, is the most likely t o indicate it, for its two isotopes notonly differ by 10% in mass, but are both present in considerableproportion.Spectra of Isotopes.Mlle. B. Perrette32 has compared the line spectrum of ordinarylead of atomic weight 207.2 with that of uranium lead, 206.14,using a vacuum arc in conjunction with a Fabry-Perot interfero-meter. Differences of the order of 0.007 8.are found for severallines,inagreement with the earlier work of M e r t ~ n . ~ ~ F. A. Jenkins34has compared the spectra of samples of mercury differing by 0.18unit in atomic weight and of chlorine differing by 0.097 unit. Noreal shift of the mercury lines could be observed, but very smallshifts, e.g., 0.0012 A. for 4741 8., were detected in the case of someof the chlorine lines.In the region of band spectjra, R. S. Mulliken35 continues hisvaluable series of papers on the isotope effect. He has studied theband spectra produced by the action of active nitrogen on the halidesof copper and shows these are explainable by quantum mechanics.In the case of the iodide, complete data are given and the wave-lengths of 260 band heads measured.Every Cue31 band was found,whenever of sufficient resolution and intensity, to be accompaniedby a weaker Cu"I band. He has reinvestigated the band spectrumbetween 3800 and 5300 B., obtained by Jevons 36 by the action ofactive nitrogen on silicon tetrachloride, and shows that the emittermust be a molecule SiN. The photographs show that each of theSi2sN band heads is accompanied by weaker satellites correspondingto Si29N and Si30N exactly a t the theoretically expected positions.W. Jevons37 has obtained evidence of the isotope effect in the bandspectra of the discharge through the vapour of stannic chloride.ArtiJicial Disintegration and Transmutation.Continuing their research on the collision of swift a-particleswith atomic nuclei, Sir E.Rutherford and J, Chadwick3s haveinvestigated the scattering of u-particles by a number of elementswith the aid of much-improved scintillation methods. Gold,platinum, silver, and copper show no deviation from the simple laws,Cornpt. rend., 1925,180, 1589; A., 1925, ii, 646.Proc. Roy. Soc., 1921, [A], 100, 84; A , , 1921, ii, 611.34 Nature, 1926, 117, 893; A,, 771.a5 Physical REV., 1926, [ii], 25, 119; A., 1925, ii, 259; ibid., p. 259; A , ,1925, ii, 346; ibid., 86, 1; A., 1925, ii, 833; ibid., p. 319; A., 1925, ii, 1020;Nature, 1926, 116, 14; A., 1925, ii, 731.36 Proc.Roy. Soc., 1913, [A], 8g, 187; A . , 1913, ii, 813.Ibid., 1926, [A], 110, 365; A., 222.Phil. Mag., 1925, [vi], 50, 889; A,, 1925, ii, 1109SUB-ATOMIC PHENOMENA AND RADIOACTIVITY. 285it being assumed that the colliding particles are point charges andthat the inverse-square law of force holds, I n the case of gold,this was proved true down to distances of approach between 3.2 XOn the other hand, light elements, suchas magnesium and aluminium, showed remarkable deviations whichwere of the same type whether the scattering angle observed was90' or 135'. No law of force yet proposed seems adequate toexplain these results, P. Debye and W. Hardmeier39 and W.Hardmeier 4O suggest that they are probably due to the incompleterigidity of the nucleus giving rise to polarisability.The subject isalso discussed by A. Smekal 41 and E. G ~ t h . ~ ~As has been already reported,& Rutherford and Chadwick demon-strated the disintegration of all elements from boron to potassiuminclusive, with the exception of carbon and oxygen, and obtainedinconclusive results with lithium and beryllium. On the otherhand, Kirsch and Pettersson stated that they had succeeded indisintegrating all these four elements, and also claimed that theycould distinguish between protons and a-particles by the qualitiesof the scintillations observed. The Vienna workers have publishedseveral papers in support of their claims,44 and Chadwick45 hasrecently reinvestigated several of the points a t issue.Using newoptical systems of great efficiency, he was unable to detect theemission of protons of a range greater than 4 cm. in air from beryl-lium, carbon, or oxygen. A very small effeot in the case of lithiumcan be ascribed to traces of impurity, Hence, whatever explanationmay be given for the discrepancies between the observations madea t Vienna and those made a t Cambridge, there seems no doubtthat these four elements have nuclei differing in some fundamentalway from the others.In contradistinction to these now well-authenticated cases oftransmutation, in which the most violently energetic forces in nature,corresponding to millions of volts, are employed, there are numerousclaims of transmutation of one element to another by the use ofprocesses of quite ordinary quality.The most important of theseis that of mercury into gold, claimed by Miethe to take place inan ordinary mercury-vapour lamp as already reported.4s Thecaution then advised has been amply justified. The claim wasand 1 x 10-11 om.Phy&ikaZ. Z., 1926, 27, 196; A,, 450. 40 Ibid., p. 574; A., 990.41 Ibid., p. 383; A., 772. 42 Ibid., p. 607; A., 880.is Ann. Report, 1924, 21, 246.44 H. Pettersson and G. Kirsch, Physikal. Z., 1924, 25, 588; A , , 1925, ii,623; G. Kirsch, ibid., 1925, 28, 379; A., 1928, ii, 621; ibid., p. 457; A , , 1925,ii, 923.4 6 Phil. Mag., 1926, [vii], 2, 1050; A., 1191.d E Ann. Report, 1924, 21, 248286 ANNUAL REPORTS ON THE PROQRESS OB CHEMTSTRY.based upon the idea that it should be quite easy to bring aboutthe collapse of a planetary electron into the positively chargednucleus.As has been pointed this is fundamentally unsound.Furthermore, such a process must result in an isobare of atomicnumber one unit less. Now an examination of all the species ofatoms known a t present reveals the fact that every pair of isobaresknown with certainty differs by two units of atomic number, andalso that elements of odd and of even atomic number differ funda-mentally in their isotopic grouping. There is obviously no evidencefor this type of change in nature.Miethe's claim has been supported by H. N a g a ~ k a , ~ ~ who employeda high-tension condensed discharge between electrodes of mercuryand tungsten, immersed in hydrocarbon oils, and detected bothsilver and gold in the residues.Ultimately, enough of the " trans-mutation " gold was prepared by Miethe to enable an atomic.weightdetermination to be made. This was performed by 0. HBnigschmidand E. Zintl,4e and the value obtained was indistinguishable fromthat of ordinary gold, viz., 197.2. At the same time, mercury wasshown by the new mass-spectrograph to contain no appreciablequantity of an isotope of mass-number less than 198 (vide supra).I n the face of these facts, i t became very difficult t o defend thetransmutation theory, and numerous attempts were made to dis-cover an alternative explanation for the presence of the gold.This led to a lively controversy as to the possibility of freeing mercuryfrom gold by distillation, A.Miethe and H. Stammreich 6o main-taining that this could be done, whilst E. H. Riesenfeld and W.Haase 5 1 and W. Venator 52 took the opposite view. Miethe'sexperiments 53 were repeated by A. Piutti and E. Boggio-Lera,"who obtained negative results, and by F. Haber, J. Jaenicke, andF. Matthias,66 who were satisfied that the minute traces of goldthey found could be attributed to the materials employed. Thesame result was obtained by E. Tiede, A. Schleede, and F. Gold-schmidt .56The experiments of M. W. Garrett 57 are particularly convincing.(?lAnn. Report, loo. cit.40 Nature, 1925, 116, 95; A., 1925, ii, 835; J. Phys. Radium, 1925, [vi],6, 209; A., 1925, ii, 1111.49 2. anorg. Chem., 1925, 147, 262; A , , 1925, ii, 924.61 Ibid., 1925,58, [B],2828; A., 264; ibkl., 1926,59, [B], 1625; A., 922.68 2.alzgew. Chem., 1926, 39, 229; A., 486.68 A. Miethe and H. i3tammreich, 2. anorg. Chem., 1926,150,350; A., 367.dl Qiorn. Chim. I d . Appl., 1926, 8, 69; A., 699.6 6 2. anorg. Chem., 1926,153, 153; A., 699.6 6 Ber., 1926, 59, [BJ, 1629; A., 922.67 Ndure, 1926, 118, 84; A., 773; Proc. Roy. Soc., 1920, [A], 119, 391;Ibid., 1925,149, 263; A., 119; Ber., 1926,69, [B],359; A.,493.A., 10168VB-ATOMIU FHlNOHENA AND RADIOAUTIVITY. 281Using every precaution, he repeated Miethe’s experiments, but evenafter an interrupted arc had been run for 288 hours in a silicon tubecontaining mercury and hydrogen, no gold could be found. Thetest employed was so delicate that he could have detected one ten-thousandth part of the quantity of gold which Miethe’s results led oneto expect, Garrett also attempted to prepare indium from tin, andscandium from titanium, in each case with negative results.Othercontributions to the subject are made by L. KauIJK8 F. S t ~ m p f , ~ ~A. S. Russell,BO (Miss) A. C. Davies and F. Horton,61 and E. Duhmeand A. Lotz.62 The balance of the experimental results is unmis-takably in support of the theoretical conclusion that the introductionof an electron into a nucleus is not to be brought about by suchmeans.Other claims of transmutation are of a more extravagant natureand may safely be set aside awaiting confirmation. R. W. Ridingand E. C. C. Baly 63 state that they are able to disintegrate nitrogenby cathode-ray bombardment and that the result of this is theformation of helium and neon.A. Smits 64 claims to have trans-muted lead into mercury and thallium in an arc, and F. Panethand K. Peters 65 have come to the surprising conclusion that hydro-gen may be turned into helium by dissolving i t in palladium.Unless all modern views of the stability of atomic nuclei are wrong,i t would appear that in all these cases the presence of an elementhas been mistaken for its creation.Radiation and the Structure of the Nucleus,The magnetic spectra of primary p-rays emitted by radioactivenuclei, and of secondary @-rays produced by y-rays, have beenwidely studied. The most important result is a definite proofthat in the pray type of disintegration the emission of the y-raytakes place after the ejection of the electron from the nucleus.Fifteen lines of low energy from 4290-12,670 volts in the p-rayspectrum of radium-B were measured by D.H. Black.66 Onanalysis of the values so obtained, it was found that eleven of thesecorresponded to an atom of number 83, whilst with an atom ofnumber 82 i t was possible to account for only six of them. Thissuggested that the original measurements of Rutherford and Andrade68 Chem. Bentr., 1924, ii, 1049; A., 1925, ii, 177.2. PAyaik, 1924. 30, 173; A., 1925, ii, 619.Nature, 1925, 116, 312; A,, 1925, ii, 924.Ber., 1926, 50, [B], 1649; A., 930.61 Ibki., 1926,117,152; A., 221.*a Proo. Roy. floe., 1928, [A], 109, 186; A., 1926, ii, 925.64 Nature, 1926,117, 13; A., 106.O 5 Ber., 1926, 59, [B], 2039; A., 1077.6 6 PYOC.Camb. Phil. ~SOC., 1925, $32, 832, 838; A., 1926, 6288 ANNUAL REEORTS ON THE PROGRESS OF CHEMISTRY.in 1914 of the natural y-ray spectrum of radium-B, which corre-sponded with an atom of number 82, were probably erroneous.These observations were therefore repeated,67 the original rock-saltcrystal method being used. The new results were in exact accordwith Coster’s data for an element of number 83. Furthermore,the energies of the three main y-rays from radium-B and the strongestfrom radium4 were measured by C. D. Ellis and W. A. Wooster 68to an accuracy of 1%. These results were also in agreement withthose calculated on the view that the emission follows the nucleardisintegration.0. Hahn and Frl. L. Meitner e9 have measuredthe p-ray spectrum of radioactinium and its products, and from theirresults the energies and wave-lengths of the y-rays from radio-actinium, actinium-X, and actinium-Q” are calculated by Meitner,’Oand shown to be those expected from the atom resulting from thea- and p-ray changes and not from the original atom, thus confirmingthe results of the Cambridge workers. C. D. Ellis and W. A.Wooster 71 give a further discussion of the p-ray type of disinte-gration in which the view of Meitner, that y-rays are emitted duringthe reorganisation of the nucleus after the disturbance caused bythe disintegration electron, is extended to the idea that the y-raysare emitted by the electronic system of the nucleus.Discussionson the origin of continuous and other p-ray spectra are given byA. Piccard 72 and by J. Thibaud.73 The latter concludes thatEinstein’snumerical relation between the energy of a y-ray and thatof the electron which it excites is completely verified. He is unableto find any evidence of the J-electron level of Barkla.Radium Products.-The natural p-ray spectrum of radium-Band -C has been mapped out by J. d’Espine,’4 who observed a bandof high-velocity particles with Hp values between 15,000 and 27,000,and gives a table of lines which agree with those already given byEllis and Skinner.75 A direct determination of the distributionof intensity in this spectrum was started by L. F. Curtiss.76 Thiswork has been continued with improved apparatus by R.W.6 7 (Sir) E. Rutherford and W. A. Wooster, Proc. Camb. Phil. Soc., 1925, 22,68 Ibid., p. 844; A., 1926, 6.7o Ibid., p. 807; A,, 1926, 106.71 Proc. Camb. Phil. Soc., 1925,22, 849; A,, 1926, 6.7 3 J. Phya. Radium, 1925, [vi], 6, 334; A., 1926, 106.834; A., 1926, 6.(0 2. Physib, 1925, 34, 795; A,, 105.Compl. rend., 1924, 179, 815; A., 1925, ii, 257; ibid., 1925,180, 138; A.,1925, ii, 176; J . Phya. Radium, 1925, [vi], 6,334; A,, 1926,106; Anw. Physique,1926, [XI, 6, 73 ; A., 333.74 Compt. rend., 1925, 180, 1403; A., 1925, ii, 622.7 5 Proc. Roy. SOC., 1924, [ A ] , 105, 60; A., 1924, ii, 85; ibid., p. 165; A.,7 6 Proc. Camb. Phil. SOD., 1925,22, 597; A , , 1925, ii, 622.1924, ii, 137SUB-ATOMIC PHENOMENA AND RADIOACTIVITY.289Gurney," whose measurements lead to the conclusion that bothradium-B and radium-C possess a genuine continuous pray spectrumquite distinct from the line spectrum which is superposed upon it.The latter is attributed to the conversion of y-rays into p-rays, theprobability of which is about 1 to 7 . The natural p-ray spectrum ofradium-D has been mapped out by L. F. curt is^,^^ and that ofradium-E by ( m e . ) I. Curie and J. d'E~pine.'~Thorium Products.-The p-ray spectrum of thorium disin-tegration products has been examined by W. Pohlmeyer 8o andby D. H. Black.81 The latter gives measurements of 17lines ascribed to thorium-B, that a t Hp 1398 being extremelystrong. For thorium-C and -D, 16 lines were measured, thestrongest being Hp 541.A group of lines of very high energies ofmore than 2.5 x lo6 volts was recorded, probably due to thorium-Dand arising from the conversion of a single y-ray in the K and Llevels of the atom. Quantitative measurements of this spectrumhave been carried out by R. W. Gurney 82 in continuation of hiswork with the radium products (vide supra). The results suggesta law of '' p-ray disintegration," namely, that no y-rays of highenergy can be emitted by those radioactive substances which expeltheir nuclear electrons with low energies. The probability thata y-ray of 150,000 volts energy emitted by thorium-€? is convertedin the K level is a t least 1 in 4. For the y-ray of 40,000 volts fromthorium-D, the probability of conversion in the L level is morethan 1 in 5.A rapid method of purifying mesothorium-2 from its mixturesis described by D.K. Yovano~itch,~~ and its magnetic spectrum isfound to contain 43 lines of energies between 8 x 106 and 3.9 .Xlo* volts. The primary p-ray spectrum of mesothorium-2 has alsobeen studied by J. Thibaud 84 and found to be similar to the second-ary p-ray spectrum of element 89, according to theory. A furtherstudy of the secondary p-ray spectrum from lead gave two lines inthe y-radiation of 333 and 459 k.v. respectively, confirming theresults of M. de Broglie and Cab~-era.~~ The reIation between the7 7 Proc. Roy. Soc., 1925, [ A ] , 109, 540; A., 1926, 5.78 0-t. rend., 1926, 181, 31; A., 1925, ii, 732.ID 2. Physik, 1924, 28, 216; A., 1925, ii, 347.s1 Nature, 1925, 115, 226; A ., 1925, ii, 177; Proc. Roy. isoc., 1925, ( A ] ,sa IbirE., 1926, [A], 112, 380; A., 990.C. Chamie, Compt. rend., 1926, 182, 380; A., 3321.$4 Compb. r e d . , 1924, 179, 1322; A., 1925, ii, 85.8 6 Ibid., 1923, 178, 295; A., 1923, ii, 109.REP .-VOL . XXIII .Physical Rev., 1926, [ii], 27, 257; A., 450.It)@, 166; A . , 1926, ii, 922.J . C h h . phys., 1926, 23, 1 ; A., 331 [compare (Mlles.) E. Gleditsch and290 ANNUAL REPORTS ON TEE PROGRESS OR OHEMISTRY.intensity of excited p-ray emission and atomic number has beenworked out by M. de Broglie and J. Thibaud.86Heat developed in Radioactivity.The increase in the heating effect of radium preparations overa period of 1st years has been measured by Mme.M. Curie aad D. K.Yovanovitchs7 and shown to amount to 11%. This is provedto be that theoretically expected from the growth of polonium.The distribution of energy developed by different types ofradiation has been investigated by J. Thibaud.88 Taking Ruther-ford and Robinson's value g9 for the total heat set free from 1 g. ofradium in radioactive equilibrium, viz., 135-137 cal./hr., andcalculating the kinetic energy of wparticles and recoil effects as117.7 cal. and of P-radiation as 12-1 cal., he ascribes the balance ofabout 7 cal. to y-radiations. He points out that the latter willnot be of constant frequency, but that their relative intensitiesenable a mean quantum t o be calculated. In this way, the meanquanta of y-radiation from radium-B, radium-C, and radium aregiven as 302, 1010, and 187 k.v., respectively.The value for 8,the number of atoms disintegrating per second, being taken as3-57 x 1010, the total energy of the y-rays is 7.27 cal./hr. Theagreement of this figure with the balance above is taken to supportthe hypothesis that each a-particle emission from the nucleus isEollowed by a single y-ray.An elegant balance method, by which the small heating effect ofy-rays may be directly measured in the presence of the a-rays, hasbeen worked out by C. D. Ellis and W. A. W o o ~ t e r . ~ ~ This consistsin measuring the difference in rise of temperature of aluminium andlead blocks exposed to the mixed rays. The a-rays, being completelyabsorbed, produce the same heating effect in each metal, but adifferential effect is produced by the y-rays owing to the higherabsorbing power of the lead.By this means they have measuredthe total y-ray energy from one curie of radium-B and radium-Cto be 8.6 & 0.4 cal./hr. From the absorption coefficients of Ahmad?lthe y-ray energieaare in the ratio of 1 to 9, so that, of the abovefigure, 0.86 cal./hr. is attributed to radium-B and 7.7 cal./hr. toradium-C, corresponding with 185 and 1660 k.v., respectively.86 Compt. rend., 1925, 180, 179; A,, 1925, ii, 165 (compare Ellis, Proc. Roy.&oc,,'1921. [A],99,261; A., 1921,ii, 422).87 J. Phya. Radium, 1925, [vi], 8, 33; A , , 1925, ii, 464.8 8 C o q t . r e d . , 1925, 180, 1166; R., 1925, ii, 464.89 P i d . Mag., 1913, [vi], 25, 312; A., 1913, ii, 269.91 Proc.Roy. Soc., 1924, [A], 106, 507; A., 1924, ii, 440; ibiel., 106, 8; A.,Proc. C a d . Phil. SOC., 1025,22, 695; A., 1925, ii, 622.1924, ii, 582SUB-ATOMIC PHENOMENA AND RADIOACTIVITY. 291R. W. Lawson92 points out that the value obtained by Hess of25.2 cal./hr, for the total heat developed by 1 g. of radium free fromits disintegration products, when corrected for the y-ray energy lost,becomes 25.5 cal./hr., a figure much better in accordance with thevalue 3.72 x 1010 for 2 than with the lower value 3.40 x 101o.wA. Holmes and R. W. Lawson 94 have made a complete and veryinteresting investigation into the effect of the radioactivity of potass-ium and rubidium in geological heat-development. For this purpose,they take for the velocity of the p-rays 0.90~ and 0*60c, and thehalf-periods 1.5 x 1012 and 1.0 x 1011 years, respectively.Theextreme rarity of rubidium renders its effect negligible, but owingto the high abundance of potassium relative to uranium and thorium,its effect is in the aggregate of the same order of importance as thatof these vastly more active elements.u-Rays.A very complete investigation of the ionisation caused by u-par-ticles in different gases has been made by R. W. G ~ n e y , ~ 5 whohas measured the total ionisation produced by beams of u-particlesof definite energy in xenon, krypton, argon, neon, helium, oxygen,hydrogen, and nitrogen. Particles of residual ranges from 7-18 om.were employed, the former limit being imposed by the small quan-tities of krypton and xenon available.I n the five monatomiagases, the ionisation increases with increasing atomic number,a result to be expected from the decreasing ionisation potential.It is less in the diatomic gases, indicating that the energy is expendedin other ways. The ratios found for different gases are not inde-pendent of the velocities of the a-particles. Gurney96 has alsomeasured the stopping powers of the five rare gases and of hydrogenand oxygen, which are in good agreement with those calculatedby R. H. Fowler.97(Mlle.) I. Curie g8 has published a series of papers on the variationof range, initial velocity, and ionising power of the a-particlesfrom polonium ; the experiments were done in oxygen and nitrogen,and it is concluded that three-quarters of the a-particles havevelocities differing by less than Q.3y0.The initial velocity is given92 Nature, 1925,116, 897; A., 1926, 5.'8 Ann. Report, 1924, 21, 283; H. Geiger and A. Werner, 2. Physik, 1924,P4 Nature, 1926, 117, 620; A., 554; Phil. Mug., 1926, [vii], 2, 1218.O 5 Proo. Roy. SOC., 1925, [ A ] , 107, 332; A., 1925, ii, 256.9 5 Ibid., p. 340; A., 1925, ii, 256.21, 187 ; A., 1924, ii, 226.Proo. C a d . Phil. Soc., 1925,22, 793; A., 1925, ii, 834 (compare 1,. Loeb9@ Om@. red., 1924, 178, 761; A., 19215, ii, 175; ibid., 1925, 1S0, 831;end E. Condoa, J . Franklin Imt,, 1926, 200, 695; A,. 1928, 5).A., 1925, ii, 348; A m . P&dque, 1826, [XJ, 8,299; A . , 1926,ii, 894292 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.as 1.593 x lo9 cm./sec. In air, the range is 3.87 om., and maximumionisation occurs a t 4.5 mm.from the end. The velocity a t thatpoint is 0.57 x lo9 cm./sec.The stopping powers of various metals for a-particles have beenmeasured by J. Comigny.g9 For speeds of 1.59 to 1.09 x 1 0 9cm./sec., the logarithms of the stopping powers, when plottedagainst atomic numbers and atomic weights, give straight lines ofslopes tan-l 0.552 and 0.5, respectively. 8. Rosenblum,l however,from similar work, concludes that, except for platinum, the massper unit area which reduces the speed of the a-particle by the samefraction is a linear function of the atomic number. The singlescattering of a-particles by gold foil has been measured for smallangles by D.C. Rose.2 His curves indicate that the K-shell is notionised to any appreciable extent.Continuing his work3 on the capture and loss of electrons bya-particles, G. H. Henderson * has determined quantitatively theratio of the number of doubly-charged to the number of singly-charged particles in equilibrium. He finds that this is independentof the material through which the a-particles have passed. J. C.Jacobsen gives measurements of the mean free path for captureand IOBS of electrons by a-particles in air and hydrogen. Fromthese, he concludes that the probability of capture of electronsis considerably greater in air than in hydrogen under conditionsin which that of loss is the same.In a series of papers, S. C. Lind and D.C. Bardwell 6 describechemical action brought about by the influence of a-particles fromradon (niton). The velocity coefficients of the reaction thesebring about in electrolytic gas show interesting variations withpressure. Saturated hydrocarbons condense, methane and carbondioxide combining to form a wax-like solid. Similar actions bythe p- and y-rays of radium have been studied by J. Errera and V.HenrL7Long-range Particles.-Tho ratio of the number of long-rangeparticles to the number of a-particles of ordinary range frompolonium deposited on various metals has been measured by (Mlle.)I. Curie and N. Ystmada.s They state that the number of long-rangem Compt. rend., 1926, 182, 1614; A., 772 ; ibid., 183, 127 ; A., 879.1 Ibid., p.198; A., 879.4 Ibid., 1925, [A], 109, 157; A., 1925, ii, 922.6 Nature, 1926, 117, 858; A., 665.8 J . Amer. Chem. Soc., 1924, 46, 2003; A., 1924, ii, 840; ibid., 1925, 47,2675; A., 1926, 4; ibid., 1926, 48, 2335; A., 1077.7 J . Phya. Radium, 1920, [vi], '7, 226; A., 1077.8 Compt. rend., 1925,180,436 ; A., 1926, ii, 255 ; ibid., p. 1487 ; A,, 1926, ii,a Proc. Roy. SOC., 1926, [ A ] , 111, 677; A., 880.Ibid., 1923, [ A ] , 102, 496.g2l; J. Pltya. Radium, 192 5 , [vi], 6,376; A., 1926, 220SUB-ATOMIU PHENOMENA AND RADIOACTIVITY. 293particles i0 roughly proportional t o the quantity of polonium. Inoxygen and carbon dioxide, their number is roughly 10 per lo7=-particles. Thea-rays from thorium8 and thorium-C’ have been studied by (Frl.)L. Meitner and K.Freitag,lousing a special form of Wilson apparatus.The ratio of the number of a-particles from thorium8 to thosefrom thorium-a‘ was34.3 : 65.7, and the observed ranges in differentgases were in agreement with the values calculated by Bohr. Long-range particles of ranges 9.5 and 11.5 cm. were in the proportion ofabout 70 and 200, respectively, per million of the whole. Thetracks of range longer than 20 cm. were much finer and are ascribedto protons. Similar work has been carried out by K. Philipp,l1who confirms these results.12I n air, there are about three times as many?Radioactive Constants.L. Bastings 1s has determined the decay constant of radium-E,1 = 0.139 d a p l , corresponding with a half-period of 4.98 days.This value is challenged by G.Fournier,l4 who employs a piezo-electrometer and obtains for three different sources values of 4.86,4.86, and 4.84 days, supporting the original value 4.85 given byThaller. On the other hand, L. F, Curtiss 15 estimates the half-period as 5.07 days, in agreement with the results of Antonof,Meitner, and Bastings. The decay constant of radon has also beenmeasured by Bastings,16 who for its half-period gives 3.833 days,a slightly higher value than that previously given by Curie andChami8.l7 B. Batscha estimates the half-period of thoron a tabout 53 seconds. W. P. Widdowson and A. S. RussellI9 haveinvestigated mesothorium-2 and ascribe to i t a half-period of5.95 hours, 4% lower than that obtained by Hahn.20 P. Bracelin’s 21measurements of the half-period of radium-I3 and radium4 givefor the former from 26.7 to 26.8 min., and for the latter 19.72 f0.04 min.A. W. Barton,Z2 using a modification of Jacobsen’sCompere Bates and Rogers, Nature, 1923, 112, 435; A . , 1923, ii, 720;Proc. Roy. Soc., 1924, [ A ] , 105, 97, 360; A , , 1924, ii, 84, 296.lo 2. Physik, 1926, 37, 481; A., 772.11 Ibid., p. 518; A., 772.l1 Compare S. Rosenblum, Compt. rend., 1925,180, 1332; A . , 1925, ii, 463.l3 Phil. Mag., 1924, [vi], 48, 1075; A., 1925, ii, 9.Compl. rend., 1925, 181, 502; A . , 1925, ii, 1110.1 5 Physical Rev., 1926, [ii], 2’7, 672; A., 771.l6 Proc. C a d . Phil. SOC., 1925, 22, 562; A , , 1925, ii, 621.l7 J . Phye. Radd’um, 1924, [vi], 5, 238; A . , 1925, ii, 8.Is 2.phyaikaE. chem. Unterr., 1924, 37, 117; A., 1925, ii, 177.19 Phil. Mag., 1925, [vi], 49, 137; A., 1925, ii, 463.2o Physikal. Z., 1908, 9, 245; A., 1908, ii, 454.a1 Proc. Camb. Phil. Soc., 1926, 25, 150; A., 553.Phil. Mag., 1926, [vii], 2, 1273284 ANNUAL REPORTS ON THE PROGRESS OF CEEMIGTRY.apparatus for the investigation of the decay constant of radium-a’,confirms the existence of this body and estimates its half-period tobe of the order of 10-6 second. The average life-period of ioniumhas been found to be 29,000 years by 0. Koblic,% who assumesHonigschmid’s figure for the ionium-thorium ratio.W. D. Harkins and W. G. Guy 24 have measured the radioactivityof many elements by a very delicate balance method. Twenty-fiveof these gave an activity less than 3.3 x 10-6 that of uranium.They conclude that rubidium is 1.39 times as radioactive as potass-ium, but the radiation from rubidium is 10 to 15 times less penetrat-ing than that from potassium, hence their activities cannot be tracedto a common source.( m e . ) S. Maracineanu 25 makes the remark-able announcement that the activity of uranium oxide is alteredby as much as 50% by exposure to sunlight, and that ordinary leadacquires radioactive properties by the same treatment. Thiswill need very strong confirmation, for it is contrary to all acceptedviews.Cosmic Rays and Xtellar Xatter.The original discovery by Kolhorster that exceedingly pene-trating rays were detectable a t high altitudes has led to very interest-ing results.Although G. Hoffmann 26 and F. BBhounek *’ considerthat a t sea level all the radiation observed can be explained as comingfrom known radioactive sources, and that the experiments of L.Myssovski and L. Tuwim 28 are not conclusive, yet R. A. Millikanhas obtained proofs of the presence of penetrating extra-terrestrialradiation a t high altitudes of a reasonably unambiguous character.In his latest communication on the subject,”O he describes the resultsobtained by sinking two specially designed electroscopes in high-altitude snow lakes. The readings obtained in two lakes a t differentaltitudes are perfectly consistent with each other, when allowance ismade for the absorption by the air between, and can only beexplained by the presence of two types of radiation of unprecedentedhardness directed towards the earth from outer space.The CO-efficients of absorption give wave-lengths 0*00038 A. and 0.00063 d.The former corresponds to 32 x 106 volts, about 50 times theps Chem. Liaty, 1926, 19, 389; A., 105.Proo. Nat. Acad. Sci., 1926,11, 628; A,, 1925, ii, 1109.BuU. A d . Sci. Roumaine, 1924, 9, [3-41, 1; A., 1925, ii, 348; Comipt.Phy8ikaZ. Z., 1925, 28, 669; A , , 1925, ii, 1110; ibid., 1926, 27, 291; A.,rend., 1925, 181, 774; A., 6.656.87 Ibid., p. 8 (compare V. F. Hess, ibid., p. 159; A., 450).Z. Phyaik:, 1925, 35, 299; A., 221.Science, 1925, 62, 446; A., 460.30 R. A. Millikan and G. Harvey Cameron, Physical Rev., 1926, 28, 851SUB-ATOMIC PHENOMENA AND RADIOACTIVITY I 295frequency of y-rays. These should be capable of producingsecondary p-rays which could penetrate brass walls 5 mm. thick.They are, nevertheless, only about one-thirtieth of the frequencyof radiation expected to result from the simultaneous annihilationof one proton and one electron.31In connexion with these cosmic rays i t is of interest to note thatastronomers have long decided that the only possible way in whichthe stars can maintain their radiation is by some procees of annihil-ation of the matter of which they are composed. I n attemptingto postulate physical conditions under which ordinary matter mightbe expected to behave in this way, very formidable difficulties areencountered. J. H. Jeans 32 does away with these entirely by boldlypostulating that matter as we know it cannot, under any conceivableconditions, transmute itself into radiation, and that the interiorof stars, that is, the vast bulk of the material universe, containselements of a type unknown and unknowable on earth. Hesupposes that these have atomic weights as high as 300, and thatin their atoms a planetary electron is capable of collapsing into thenucleus and simultaneously annihilating itself and a proton in thatprocess. I n order to avoid explosive instability, he makes theingenious hypothesis that, as soon as the temperature rises so highthat all the planetary electrons are stripped from the nucleus, theoperation becomes impossible. This theory covers most of thefacts, but the quality of cosmic radiation, which is the only form ofinformation on the point that we can get from the stars a t present,8eems to indicate a more gradual type of degradation.F. W. ASTON.s1 M. Home, Nature, 1926,117,194; A., 22133 Nature, 1926, 118, [Supp.], 29

ISSN:0365-6217    

DOI:10.1039/AR9262300280

出版商:RSC    

年代:1926

数据来源: RSC

摘要:

SPECTROSCOPY,THERE: have been several well-marked stages in the development ofspectroscopy, and during some of these the chemical importance ofthe subject has certainly been small. This is not true of its presentaspect, and it seems probable that its chemical interest will con-tinue to increase for some time. In the years following the pioneerinvestigations of Bunsen and Kirchoff, the interest lay in such workas the assignment of the many new spectra to the elements andcompounds responsible for them. This led to important chemicaldiscoveries, and, in particular, t o the recognition of new elements.The second phase of the subject was marked by importantinstrumental improvements-the introduction of high-dispersionspectroscopes, interferometers, etc.-rather than by new theoriesor discoveries.With the aid of these improved instruments,trustworthy wave-length standards were constructed, and by 1913,when this phase ended, about 100,000 lines had been measuredwith tolerable accuracy. In spite of this industry, scarcely anyprogress had been made with a theory of spectra, and the cataloguesof lines in Kayser’s “ Handbuch der Spectroscopie ’) are a sufficientdemonstration of the state of the subject in the absence of anyco-ordinating theory. Within the last twelve years, the quantumtheory of spectra has proved itself competent to establish order,and even spectra as complex as that of the iron arc have beendisentangled into related groups of lines on an ordered plan. Theuses of the new theory are not limited to formal spectroscopy.Atheory of atomic structure has been based upon it ; and problems ofvalency and molecular structure, which have intrigued manygenerations of chemists, may be solved by its further application.The growth of spectroscopy in all its branches has recently beenso rapid that a brief report of this nature must, in any case, beinadequate. The material selected for review has been chosen tocover the very varied chemical interests of the subject.The Interpretation of Line Spectra.From the chemist’s standpoint, the most important product ofthe study of line spectra is a useful atomic model. It is, of course,doubtful whether anything so crude as a model can adequatelyrepresent those changes of atomic configuration which apparently29SPECTROSCOPY. 297produce spectra, but the approximations to reality which cancertainly be achieved are in any case invaluable.The com-plete line spectrum of an element consists of a number of series,and the component lines of each series are connected by a simpleexpression.In the hydrogen spectrum, which is the simplest ofall, the expression takes the formThe empirical facts of line spectra are briefly these.Y = N(l/n2 - l/m2),where n and rn have integral values, and N is the “ Rydberg con-stant.” Replacing n by the values 1, 2, 3, and 4, and m by suitablesequences of integers, four series are obtained corresponding toknown lines in the far ultra-violet (n = l), the visible and nearultra-violet (n = 2), and the infra-red (n = 3 and 4 *).The samesimple expression, with iV replaced by 4 N , gives the frequenciesof the series lines of ionised helium. The empirical expression,even in an approximate form, for the series emitted by more com-plex atoms contains two more constants, and becomesv W l / ( n + !+)2 - + c12)21,where p1 and p2 are fractional constants. The spectrum of eachelement contains various series, in each of which v1 and p2 haveCharacteristic values (principal, diffuse, sharp, etc., series), and,further, each series may be composed of doublets, triplets, or ofsti? more complex groups of lines.?No theory of these regularities could be developed on the basisof classical mechanics ; in fact, it was difficult to account in thisway even for the existence of sharp lines in a spectrum, quiteapart from their distribution.The general belief, which hasproved erroneous, was that on atom must possess characteristicvibration periods corresponding to the frequencies of its spectrallines. This standpoint was abandoned in the successful Bohrtheory, first published in 1913. The two terms which appear inthe empirical expression for a series line (e.g., Nin2 and iV/W forthe hydrogen linee) are now correlated with two states of the atom,with different internal energies. The line is supposed to be emittedowing to a. change from the state with the greater energy W , tothat with the less W , (by a mechanism still obscure) and the liberatedenergy appears as a quantum of light of a definite frequency givenby hv = TV, - W2. The internal-energy changes in the atom* This fourth series was pradieted by Bohr, and observed by F.S. Brackett(dstrophys. J., 1922, 58, 154; A . , 1923, ii, 103).For full discussion of these regularities, see A. Fowler, “Report onSeries Spectre,” 1922, Physical Society of London; and F. Paschen andR. Gdtze, “ Serimgesetze der Linienspectren,” 1922, Springer, Berlin.K 298 A ~ A L REPORTS ON TEE PROGRESS or OHEMISTRY.are taken to be due to variations in the orbits of the valency elec-trons. It was found that the series relationship could be accountedfor with the further assumption that only orbits with certain radiiare possible ‘‘ stationary states,” viz., those for which the angularmomentum of the system is a multiple of a fixed unit.A d e h i t equantum number, corresponding to this multiple, was ascribed toeach orbit. This quantum number determines roughly the sizeof the orbit, and is now called the “ principal quantum number.”Bohr was at once enabled to calculate the value, hT, of the Rydbergconstant, to account for the line spectrum of hydrogen, and to pre-dict the spectra of singly-ionised helium and doublyionised lithium IThe theory could, in fact, account for the spectral behaviourof the simple systems consisting of a nucleus with a charge e, Ze,3e, etc,, accompanied by a solitary planetary electron. In con-sidering such atoms, the motions of the electron could be treatedas if controlled by a pure Coulomb (or inverse-square) attractionfrom a point nucleus, and the orbits were therefore taken t o beellipses, with the circle as a special case.It was soon realised thatthis simple treatment could not be continued in the extension ofthe theory to more complex atoms, or even in the explanation ofthe h e structure of the hydrogen lines, revealed under high dis-persion. The presence of other electrons in addition to the radiat-ing one disturbs the simple Coulomb field, and the effect of thisperturbation, it has been shown, is t o cause a uniform precessionof the major axis of the elliptical orbits in their own plane.* Thisprecessional frequency must vary with the ratio of the major tothe minor axis, becoming greater as this ratio increases. It hasbeen found that by introducing a second quantum number con-trolling the ratio of the axes, and therefore also the precessionalfrequency, some of the regularities in the spectra of complex atomscan be accounted for.This second quantum number is called the“azimuthal quantum number.” In effect, each of the originalBohr orbits, with a given principal quantum number, is thus replacedby a group of orbits of difierent ellipticities, and with azimuthalquantum numbers 1, 2, 3, 4, etc. The energy of each orbit in agroup will be different, the amount depending on the degree ofperturbation of the central field. These differences are correlatedwith the appearance of the constants and pLZ in the series formulagiven above. In each sequence of terms of the type N/(m + p)2,* The disturbing force in the hydrogen atom is taken to be the relativisticchange of rnms of the electron, due to its varying velocity in an ellipticalorbit. This perturbation is, of course, of e much smaller order than thatproduced by the presence of other eleotrops.The latest views on the hydrogenspectrum are discussed by A. Sommerfeld in “ Three Lectures on AtomicPhysics,” 1936, hlethuenSPECTROSCOPY. 299the azimuthal quantum number (k, the “ ellipticity ” of the orbits)is regarded as remaining constant, whilst the principal quantumnumber (Lea, the size of the orbits) takes all possible values. Theseparate existence of the principal, diffuse, etc., series of an elementis therefore due to the precessional motion of the electron in anon-Coulomb field, and all such series should coincide in the spec-trum of an atom in which there is no perturbation of the field-acondition nearly realised in the hydrogen atom.The occurrence of doublets, triplets, etc., in series spectra stilllacked a theoretical interpretation.This was provided in 1920 bySommerfeld with the introduction of a third or “ inner ” quantumnumber. Shortly afterwards, M. A. Catalhn 1 discovered that thespectra of some elements, such as manganese and chromium, containgroups of lines of previously unsuspected complexity such as septetsand octets. These “ multiplets ’’ were found to fit the scheme of‘’ inner quantum numbers ’’ devised for the simpler groups. Thisthird quantum number was introduced in purely formal manner,but the necessity for its introduction is regarded as an indicationof a precession of the orbital plane of the electron about theinvariant axis of the atom. To deal with the Zeeman effect andother phenomena, a t least one more quantum number must beadded to the previous three, so that a t present an electronic orbitis considered t o require four suitably chosen quantum numbers forits complete description.There is a difficulty in finding a physicalinterpretation for the fourth quantum number, as an electronhas always been treated as a point-mass with only three degreesof freedom. The explanation has been offered that the dimensionsof the electron must also be taken into account, and that it maypossess energy in virtue of a spinning motion about an axis of rotationin the electron itself.There is little doubt, however, that additionalquantum numbers will be found necessary for the complete descrip-tion of spectroscopic obser~ations,~ and it is clear that the import-ance of the physical model is a t present diminishing and that manydevelopments in spectroscopic theory are now proceeding alongpurely formal lines. The resources of the model, nevertheless, meby no means exhausted, as the investigation of H. N. Russell andF. A. Saunders4 into the arc spectra of the alkaline earths has* Compare G . E. Uhlenbeck and S. Goudsmit, Nature, 1926,117, 264; A.,215.Compare A. E. Rusrk snd R. L. Chenault, Phil. Mag., 1925, [vi], 50,937;d., 1925, ii, 1103, and the introduction of a “fine quantum number’’ toaccount for line satellites.’ Astmphya. J., 1926, 61, 38; A . , 1925, ii, 911. See also A. E. Ruark,J. Opt. SOC. Amer., 1925, 11, 199; A., 1926, ii, 1016.Phil. TTane., 1922, [ A ] , 223, 127; A., 1922, ii, 726300 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRP.recently proved. These spectra contain series which do not fit intothe ordinary series scheme, and yet are related to it, as shown by thetriplet separations, etc., and the terms expressing these additionalseries have been called ‘I anomalous terms,” or ‘‘ primed terms.”It has been found that these spectra can be accounted for in termsof the model by postulating simultaneous changes in the orbits ofboth the valency electrons of the alkaline earths ; the frequency ofthe line emitted is determined by the algebraic sum of the energychanges involved.This pretty extension of the original theory 6has served as a valuable guide to other spectra. Thus it is probablythe simultaneous movements of electrons which account for theextreme complexity of the spectra of the halogen atoms, and ofother atoms containing several loosely-bound electrons.Only the behaviour of the valency electrons has been consideredin the preceding account, but the ultimate goal of the study ofline spectra, so far as it is concerned with an atomic model, is thecomplete assignment of orbits to all the electrons surrounding thenucleus of any atom. The pioneer attempt a t a spectroscopicsolution of this wider problem was made by N. Bohr 6 from con-siderations of both X-ray and optical spectra.The assignmentof orbits involved calculations based on classical mechanics andthe correspondence principle which have since been criticised. HLconclusions have been corrected and developed, especially byJ. D. Main Smith and by E. C. Stoner,* who utilised other relevantdata such as are aeorded by valency regularities, X-ray intensities,etc. It is impossible to enlarge on their results in this Report, buti t would seem that the electronic configurations of all the elementsare now known with a fair degree of certainty. A general theoryof complex spectra has just appeared which confims these deduc-tions of configuration with the aid of semi-empirical rules forfixing the inner orbits. Hund has also attacked the converseproblem-the prediction of spectroscopic terms from a knownelectronic configuration-and has predicted the constitution of theterms in the rare-earth spectra,1° which have as yet defied empiricalanalysis.There are evidently good grounds for Fowler’s surmise 11that in the future the theory of spectra will be so far developed6 For general theory, see W. Heisenberg, 2. Phyaik., 1925, 32, 841; A , ,6 Ann. Phyeik, 1923, [iv], 71, 228; A . , 1923, ii, 679.7 ‘( Chemistry and Atomic Structure,” 1925, Benn.8 Phil. Mag., 1924, [vi], 48, 719; A . , 1925, ii, 85; ibid., 1925, [vi], 49,1289; A., 1925, ii, 618.9 F. Hund, lac. cit.; and 2. Physik, 1925, 34, 296; A , , 1926, ii, 912, 1104.1925, ii, 729; and F. Hund, ibid., 33, 345; A . , 1925, ii, 912.10 2.Physik, 1925, 33, 856; A . , 1925, ii, 1038.11 Pres. Address. Brit. Assoc.. Section A, 1926SPECTROSUOPY. 301that it will become possible to calculate the positions and intensitiesof spectral lines with greater accuracy than they can be measured.Line Intewities.An experimental departure in which considerable progress hasbeen achieved in recent years is the quantitative study of lineintensities. Spectrophotometry itself is a comparatively latearrival, and spectroscopists in the past have usually been contentwith visual comparisons of intensity, which cannot be more thanqualitative in character. L. S. Ornstein, H. B. Dorgelo, and theirassociates l2 have recently made accurate intensity comparisons oflines, by photographic methods, beginning with a study of doubletand triplet intensities, and extending the work to the comparisonof lines in quite different spectral regions.In the latter measure-ments, the experimental difficulties are vastly increased, owing tothe varying sensitivity of the photographic plates for different wave-lengths. The principle of their measurements is the usual one ofreducing the intensity of a stronger line by introducing screens ofknown opacity until, in an equal time of exposure, it produces thesame blackening of the plate as the weaker line. In this way, alldiscussion of the uncertain law of blackening in relation to exposuretime is avoided. The results of their measurements are of sur-prising simplicity. For example, the intensity ratio of the pairsin the sharp series (213 - ms) of the alkali metals was found l3t o be 2 : 1, within the experimental limit of 4%.For the tripletsin the alkaline-earth spectra the ratios were 5 : 3 : 1, and, in general,simple integral ratios were found to govern the intensities of thecomponents of multiplet's of any complexity, both in arc- and spark-spectra. It is from results such as these that one may hope forinsight into the mechanism of spectral emission, a subject whichthe Bohr theory has so far left very vague. The authors havedeveloped " summation rules ') from their observations, by whichthe intensity ratios in a group of lines can be predicted from thestatistical weights of the initial and final states of the atom, whichare concerned with the emission of the lines.Results of interest of another kind have emerged from similarmeasurements on lines in different spectral regions.(Miss) C. E.Bleeker and I. A. Bongers l4 measured the intensity distributionamong the members of the sharp and the diffuse series of rubidiumand cesium when excited in flames of different temperatures, andSee reviews of methods, results, and literature : L. S. Ornstein, PTOC.Physical SOC., 1925, 37, 334; H. B. Dorgelo, Physikal. Z., 1925, 28, 756;A., 1926, 109.l3 H. B. Dorgelo, 2. Physik, 1924, 22, 170; A . , 1924, ii, 282.l4 2. Phyaik, 1924, 27, 196; A . , 1926, ii, 7730.2 ANNUAL REPORTS ON TRE PROGRESS OF CHEMISTRY.they found that the distribution is independent of such temperaturevariations. This constancy of ratio would not be expected if thelines were simple temperature emission, as their intensities shouldthen be controlled by Kirchoff's law, and the ratio would varywith temperature.On the other hand, similar measurements havesince been made on the principal-series lines15 and the relativeintensities have been found to vary with temperature in the expecteddirection. It is concluded that the principal series may be emittedas temperature radiation, whilst the excitation of the subordinateseries is purely chemical, and is caused by the reactions proceedingin the flame.Atomic Absorption Spectm.When an element gives a monatomic vapour, it is possible tocompare the emission and the absorption spectrum of its atoms. Thetwo spectra are found to be closely related, but the relationshipwas very puzzling before the advent of the Bobr theory.Nonew lines appear in the absorption spectrum ; indeed, it is alwaysmuch simpler than the emission spectrum. Thus alkali-metalvapours only absorb wave-lengths corresponding to the lines oftheir " principal " series. The diffuse and the sharp series, which arequite prominent in the arc emission spectrum, do not appear inthe absorption spectrum a t all. The reason for this selective actionof the vapour is now obvious. The valency electrons of the un-excited atoms are always bound in the innermost orbit, called the" ground " or " normal )' orbit. This, of course, has characteristicprincipal and azimuthal quantum numbers. It is only the lineswhich correspond (in absorption) to a transition from this particularorbit to outer ones which can appear in the absorption spectrum.There is no mechanism by which the remainder can be absorbed.Such observations, therefore, may be used in determining thenormal state of the atom, and they have frequently been employedfor this purpose.16It is a further deduction from the theory that if a sufficientconcentration of excited atoms, with electrons in outer orbits,can be produced in the vapour, then additional series should appearin absorption.Forexample, R. W. Wood l7 observed abnormal absorption in mercuryvapour which was irradiated with an intense beam of X 2537, theThis point has been verified in several ways.18 (Miss) C .E. Bleeker, Tram. F a r d a y Soc., 1926, 21, 479; A,, 657.18 Bog., for V, Ti, So, H. Gieseler and W. Grotrian, 2. Phyeik, 1924, 25,342; d., 1924, ii, 713; and for the iron group, E. v. Angerer and G. J. JOOS,Ann. Physik, 1924, [iv], 14, 743; A., 1924, ii, 841; and K. Majumdar, 2.Phyaik, 1926, 89, 562.1' Proc. Roy. Soc., 1924, [ A ] , 106, 079; A., 1925, ii, 3SPECTROSCOPY. 303resonance line. The normal atoms absorbed this radiation, and,in the interval before recovery of the normal state by re-emissionor collision, they were able to absorb light corresponding to othermercury lines. W. H. McCurdy 38 observed the absorption of thewell-known yellow line 5875, and of 4471, etc., by excited helium.When atoms possess metastable states, it is comparatively easyto obtain the necessary concentration of excited atoms by electricalexcitation. H.B. Dorgelo,le for example, observed such phenom-ena in neon, and used the time interval between the cessation ofexcitation and the disappearance of abnormal absorption to measurethe life-periods of the metastable states. Finally, it is a deductionfrom Saha's theory of temperature ionisation 2o that a t sufficientlyhigh temperatures a proportion of excited atoms must be inequilibrium with the normal variety, the source of the excitationbeing the violent thermal agitation. At these temperatures, theabsorption spectra should become richer in lines, and should includesubordinate series. This phenomenon has been experimentallyrealiscd with several vapours.A. S. King 2 1 found that the Museand the sharp series of the alkali metals appeared in absorptionwhen the vapours were heated in an electric furnace to about 2000".Many astrophysical observations fit in with the same view. TheBalmer series of hydrogen is prominent in the absorption spectrumof many classes of stars, but it has proved excessively difficult toproduce the series in absorption in the laboratory.22 The reasonfor the discrepancy is that the series is emitted during the returnof the electron from outer orbits to the second one. The normalorbit is the first, and so atomic hydrogen as produced in thelaboratory can absorb only the Lyman or ultra-violet series. Onthe other hand, the temperature of the stars is suflcient to securea large enough proportion of excited atoms of the type which canabsorb the Balmer series, i.e., of those with the electron in thesecond orbit.In addition to their line spectra, metallic vapours exhibit a veryinteresting continuous absorption.This begins suddenly a t thelimit of the series absorption and extends with decreasing intensityinto the region of shorter wave-lengths. Such absorption isexhibited, for example, by sodium vapour, and it has been thesubject of recent study by G . R. Harrison.= The same type ofl a PTOC. Nat. Acad. Sci., 1926, 12, 231; A., 549.l9 2. Phyeik, 1925, 34, 766; A., 1926, 101.2o See Ann. Report, 1923, 20, 5.Asttophys J., 1922, 56, 380; A., 1922, ii, 810; see also N. K. Sur andR. N. Ghosh, Phil. Mag., 1925, [vi], 49, 60; A ., 1926, ii, 453.xx See, however, B. W. Wood, Phil. Mag., 1926, [vii], 2, 876; A,, 1069.** Phyeical Rev., 1924, 24, 466; A., 1926, ii, 6304 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.spectrum is also observed beyond the limit of the EaIrner series insome stars such as Vega. These phenomena indicate the existenceof a photo-electric effect in the vapour, for, since absorption oflight of the same wave-length as the series limit is just sufficientto produce ionisation of the atom, it follows that with absorptionof greater frequencies the electron is not only freed, but is ejectedwith an appreciable kinetic energy as well. As the absorption iscontinuous, ordinary quantum restrictions cannot apply to it, butattempts are being made to formulate a quantum theory of suchspectra,24 especially as parallel phenomena have proved ofimportance in the X-ray region.Corresponding continuous emission spectra are also known, e.g .,for heli~m.~5Molecular Spectra.As would be anticipated, in number and complexity molecularspectra vastly exceed those of the elements, and the theoreticaltreatment they have received is correspondingly incomplete, inspite of the wide interest they have aroused during the last eightyears. Ever since the pioneer investigations of Hartley andHuntingdon in 1879, much attention has been paid to the spectraassociated with liquids and solutions, and absorption curves havebeen widely, and often dangerously, quoted in discussion of theconstitution of organic molecules.From the present theoreticalstandpoint, this work is of very little use. The only molecularspectra which can hope for an immediate theoretical interpretationare those of gases and vapours. I n liquids, the influence of neigh-bouring molecules introduces incalculable effects on the spectra.In general, it is true, if a vapour exhibits a spectrum composedof closely-packed fine lines, then the liquid or solution will show acorresponding absorption band, shifted in position, and with thefine structure merged into a continuous absorptiom26 There is,however, no more necessary connexion between the two thanthere is between the absorption spectrum of sodium vapour andthat of the liquid metal.Even when the discussion is limited to the spectra of gases andvapours, the amount of available material can hardly be exaggerated.The molecules of which the spectra are known are not restricted tothose which have been isolated in the laboratory. In fact, many,or most, of the better-known molecular spectra originate from24 J.R. Oppenheimer, Nature, 1926, 118, 771.2 J F. Paschen, Sitzungaber. Preuse. Akad. Wiss. Berlin, 1926, 135; A., 7 6 6 .* 6 Compare J. E. Purvis, J., 1923, 123, 2516; and H, G . de Laszlo, Proc.Roy. SOC., 1926, [ A ] , 111, 355; A,, 775SPECTROSCOPY. 305such molecules as CN, CH, NH, OH, which are incomplete accord-ing to the ordinary valency rules. Such fragmentary moleculesare evidently produced in great numbers from ordinary compoundswhen the latter are excited by the usual methods of obtainingspectra-such as the arc and flame, or in vacuum tubes-and theirlife is suficiently long to allow the emission of characteristic spectra.The observation of the spectra of more complex molecules such asthose of ordinary organic compounds is, in fact, seriously restrictedby this disintegrating effect of the exciting force, and as suchobservations are often of especial interest to chemists, the methodsof overcoming the difficulty, and of obtaining the spectra ofunchanged molecules, may be enumerated.First, if a rapid stream of vapour is passed through a vacuumtube, the spectrum of the ordinary molecules will be enhanced a tthe expense of the spectra of the fragments, as these are given noopportunity of collecting in the tube.Schuster, many years ago,obtained the spectrum of NH, by this method, although a vacuumtube med with ammonia in the ordinary way only shows thespectra of nitrogen, hydrogen, and NH. Secondly, the dischargemay be so modified that its disintegrating action is minimised.W. H. McVicker, J. K. Marsh, and A. W. Stewart observed that thepassage of a high-frequency, or Tesla, discharge through organicvapours, such as those of benzene and its derivatives, gave rise t ospectra which were evidently those of the intact molecules. Ina series of papers since 1923 they have described many such spectra.27The same spectra can be excited as fluorescence in the vapour,but their intensity is then too low for practical purposes. Finally,there is the method which has been most generhlly adopted-the observation of the absorption spectrum of the vapour.Bearingin mind the conclusions of the previous section, it might be expectedthat only a part of the full molecular spectrum would be obtainedin this way. Spectra due to the change of the molecule from oneexcited state to another should not appear, but only those in whichthe normal state of the molecule plays a part, Actually there isusually very little difference between the absorption and the emissionspectrum of a complex molecule, a conclusion reached, e.g., byMcVicbr, Marsh, and Stewart in the investigations just quoted.One may conclude that the number of possible excited states ofsuch molecules is strictly limited by the alternative of disintegration.Band spectra are as characteristic of molecules as series spectraare of atoms.All evidence, both experimental and from theory,goes to show that an atom cannot emit a spectrum with bandFirst paper, J., 1923, 123, 642; 888 also Phil. May., 1924. [vi], 48, 6211 iA,, 1925, ii, 86306 ANNUAL REPORTS ON THE PROQRESS‘OF CHEMISTRY.characteristics. There have certainly been recent statements tothe contrary. M. DuffieuxZ8 asserts that measurements of thephysical half-widths of the lines in the ‘‘ cyanogen ” bands prove theemitter to be the nitrogen atom. The width of a line, however,often exceeds that due to the simple Ddppler effect. The linemay, for example, be an unresolved doublet, and there are manycauses of further broadening. The method can only be reliedupon to give a minimum value for the molecular weight, and suchmeasurements merely prove that the emitter of the ‘I cyanogen ’)bands cannot be lighter than the nitrogen atom, whilst it may bemuch heavier.Actually, there is conclusive evidence of otherkinds that both nitrogen and carbon are essential for the appear-ance of the spectrum, and that it must therefore be of molecularorigin.The empirical relation between the lines in a band spectrum,discovered originally by Deslandres, has been expressed in manyforms, from which we may seIect v = A + Brn + Cm2, whereA , B, and C are constants and m takes a succession of integralvalues. A typical band contains a large number of lines, crowdingtogether towards a sharp lr head.” This head ” may be at eitherthe long 01 the short wave-length end of the band, which is said tobe (( degraded ” in the opposite direction to the head.A completeband spectrum usually consists of several groups of such bands.This description hoIds for band spectra in the visible and the ultra-violet region. Bands in the infra-red may have a much simplerstructure (see below). It has always been realised that the empiricalexpression was only an approximation, failing near the head, andJ. N. Thielej29 as early as 1897, suggested that the head of a bandcould not be taken to have the same important physical significanceas the limit of a series spectrum, but that its position was in somesense accidental. The quantum theory of band spectra, whichhas grown up during the past 8 years, has enabled their analysisto be carried much further by providing us with an insight intotheir constitution, and, incidentally, Thiele’s supposition has beencompletely confirmed.The internal energy of an atom can only change by the move-ment of one or more electrons from inner to outer orbits, or viceversa.The possible changes in a molecule are not so limited. Inthe discussion of band spectra, three types of energy change arerecognised : (1) Changes in energy of rotation of the molecule,(2) changes in energy of vibration, and (3) changes in electronic con-28 Ann. Physique, 1925, [XI, 4, 249; A . , 1925, ii, 1023; Nature, 1926, 117,302; A,, 336.Aatrophya, J., 1897, 6, 66SPECTROSCOPY.307figuration. The production of a line in a band spectrum in generalinvolves changes of all three types, and the frequency of the lineis determined by the algebraic sum of the three energy changes,according to the Bohr frequency condition mentioned above(AE = hv), but spectra are obviously to be expected as well whichcorrespond t o molecular transitions affecting only the rotationalenergy, or only the rotational and vibrational energies. Suchspectra are known, and it is from a consideration of these that thegeneral theory can best be approached.Rotation Spectra .-The quantum restriction placed upon mole-cular rotation is that, if the system is rotating and not emitting,the angular momentum must be an integral multiple of h/2x.Thisleads to the following expression for a pure rotational spectrumv = h(2m - 1)/8x21,where I is the moment of inertia of the molecule and nz takes theusual succession of integral values. Such a spectrum would consistof a number, of equallyspaced lines. From non-spectroscopicevidence, I ig known t o be of the order of lo4 for lighter molecules,and therefore such rotational spectra should appear in tllc farinfra-red, between, say, 30 and 100 p, This is a m c u l t regionfor experiment, but such ban& have been found in the absorptionspectrum of water vapour, etc. A recent investigation is that ofM. Czerny 30 on the rotational spectrum of hydrogen chloride.Rotation- Vibration Spectra.-If the molecule is treated as a simpleharmonic oscillator, then the vibrational energy should only changeby multiples of definite energy unit,* which may be written hv,.Superimposed upon this change will be alterations in the rotationalenergy, of the kind just mentioned, and these may be either positiveor negative in sign. The result should be the appearance of aspectrum of the type1) = nv0 f h(2m - 1)/8X21,i.e., systems of equally-spaced lines disposed about fundamentalfrequencies nv,, n being a succession of integers.Actually, anotherfactor must be taken into account. If the oscillation energy changes,then the mean distance of separation of the atomic centres willalso change, and so must the value of I . Further, changes in therotational velocity will react on the vibrational energy.The netresults of these disturbances are : (1) In such spectra the lines arenot quite equally spaced but close up slightly with increasingso 2. Physik, 1925, 34, 227; A . , 1926, ii, 1024.* Leaving out of account the restriction set by the Selection Rules, whichdisappears with non-harmonic oscillators308 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.frequencies, and (2) the “ over-tone ” bands, corresponding todifferent values of n, are also not quite equally spaced.Many such spectra are known in the near infra-red region (1-10 p).It must be mentioned that the (‘ zero lines,” corresponding tom = 0, do not appear in observed spectra, and this has led to muchdiscussion concerning the possibility of the “ rotationless state.”Bands involving Electronic Chnges.-The most general case of amolecular energy change is one involving, not only rotational andvibrational changes, but also the transition of a valency electronfrom one orbit to another.The energy associated with such atransition is of the same order as that of the atomic transitionswhich produce line series, and therefore “ electronic ” bands areusually found in the visible or ultra-violet regions. The expressionfor such spectra must clearly be more complex than those previouslygiven. For one thing, the moment of inertia of the molecule willbe considerably affected by electronic changes. Suppose themoment of inertia of the molecule in the initial state is I , and inthe final state, after emission, it is I’. Then if hvk is the vibrationalenergy change and hv, the simultaneous electronic change, the linesof the band should be given byit being assumed that the selection rule holds, viz., that m can changeonly by f 1.This expression is of the same form as the empiricalone mentioned previously, viz., v = A + Bm + Cm2, but now thethree constants have been assigned a definite physical significance.It will be noted that the theory as given above would predict twoseries of band lines starting from a common (‘zero line,” andcorresponding, respectively, to an increase and a decrease of therotational quantum number during emission. It has been foundthat the rotational quantum number may also remain constant,in which case a third series should start from the same zero line,and be given byIn general, then, a band should consist of three branches :Zero (Q) branch, v = A + Cm2 [m + m].Positive (R) branch, v = A + Bm + Cm2 [m + (m - l)].Negative (P) branch, v = A - Bm + Cm2 [(m - 1 ) --+ m].A graphical illustration of the relationship of the three branchesis given in Fig.1SPECTROSCOPY. 309The concentration of lines a t the head of a band is a more orless accidental result of the way in which the P-curve bends backupon itself, with increasing values of m. The important frequency,it is now realised, is not the head, but tjhe zero line, i.e., A, theconstant in the band law. The zero line itself (and often neigh-bouring lines also, in each branch) is not developed in observedspectra.vk in the formula will, in general, have several values, as therewill be various vibrational states, and a band head will correspondF I G .I.m--------- -- - - - -A HEADto each. From many observations,3l i t would appear that thedifferences between the various values of vk are often nearly thesame for the '' electronic ') bands in the ultra-violet and the visibleregion as for the " vibration-rotation " bands in the near infra-red.The factors determining the intensity-distribution among thecomponent lines in a band are still somewhat uncertain,32 but ingeneral the most intense line will be that associated with the mostprobable rotational velocity, so that the intensities should increasewith the rotational quantum number (m) up to a certain maximumand then decrease gradually to a negligible value.AH the tem-perature rises, the intensity-maximum should move to the highermembers of a band, and more lines should become visible, corre-sponding to greater rotational velocities. Several observers haves1 Compare E. C. C. Baly, Phil. Mag., 1915, [vi], 30, 510; A., 1916?ii, 714.?z Compere R. Sewig, 2. Phy8ik. 1926, 96, 511; A,, 223310reported such temperature-effects. R. T. Birge 33 found them forthe cyanogen bands. R. S. Mulliken34 notired that many morelines appeared in the arc spectrum of BO and of CuI than whenthe same spectra were excited a t ordinary temperatures by activenitrogen. J. C. McLennan, H. G. Smith, and C. A. Leas6 foundthat the expected intensity changes occur in the He, spectrumwhen the vacuum tube is surrounded by liquid air or hydrogen.The foregoing theory is the basis of the modern analysis of bandspectra, but, as would be expected, the spectra of most moleculesdo not conform exactly with the simple theory, but exhibit peculi-arities of their own.For example, it is not uncommon to find morethan the theoretical three branches starting from a common zeroline, and as many as twelve have occasionally been recognised.One modification of the theory which has been necessary is theintroduction of '' half-quantum " numbers. The expressions givenabove demand that the P and R branches should extrapolate intoeach other, as the constants are the same for both. More usually,however, the extrapolated lines of one branch fall exactly half-waybetween the observed lines of the other.This has led to theassumption that there are two sets of rotational states, with quantumnumbers differing by 4. The same assumption offers an explanationof the '' missing lines " near the band origin.Much interest a t present attaches to the investigation of thevarious electronic states of molecules. Theory suggests, as wehave seen, that an entire system of bands corresponds to a singleelectronic transition, and hence to a single line, or more generallyto a single multiplet in an atomic spectrum. Analogies haveaccordingly been sought between the excited states of atoms andthose of molecules. The band spectrum of helium provided thefirst evidence of such a parallel. This spectrum was discovered,and has since been analysed, by W.E. Curtis.36 It is attributedto an unstable molecule He, formed in the discharge by the unionof two atoms in metastable states. A. Fowler 37 observed that theheads of some of these bands were arranged in the same way asthe lines in a series spectrum, and that the Rydberg constant hadeven its normal line-spectrum value. 0. W. RichardsonS8 hasjust disentangled six Q branches from the maze of lines in theANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.3s A8tWphy6'. J., 1922, 55, 273.s4 Physical Rev., 1925, [ii], 25, 291; 26, 15; A . , 1925, ii, 348, 833.3 6 Proc. Roy. SOC., 1925, [ A ] , 113, 183.3 8 Ibid., 1913, [ A ] , 89, 146; A., 1913, ii, 811; ibid., 1922, [ A ] , 101, 38;37 Ibid., 1915, [ A ] , 01, 208; A., 1915, ii, 118.See also W. E. Curtis andIbid., 1826, [A], 118, 568.A., 1922, ii, 330; ibid., 1923, [A], 103, 315; A., 1923, ii, 361.R. cf. Long, &!id., 1925, [ A ] , 108, 513; A , , 1925, ii, 722SPECTROSCOPY. 311secondary, or molecular, spectrum of hydrogen, the zero lines ofwhich are all arranged according to a line-series law, with termsalmost identical with the corresponding terms of the helium-doublet series, so that we have here the band analogue of thehelium-doublet principal series. It is not s U r p r i s 4 that thespectra of the two simplest possible molecules have the closestconnexion with line spectra of all the band spectra so far examined,but there are indications that the electronic states of more complexmolecules also tend to follow the same fundamental law>9 R.S.Mulliken in a series of papers,4o in which the work of other authorsis also summarised, has put forward evidence for analogies betweenthe electronic states of certain molecules and those of atoms possess-ing the same number of valency or outer electrons ; e.g., the mole-cules BO, CN, SiN, A10 all have one valency electron (on the“ octet ” theory), and just as the principal series of sodium (withits one valency electron) is composed of doublets, so these moleculesgive rise to double-headed bands. In the same way, triplets appearin the spectra of the alkaline earths, and triple-headed bands inthe spectrum of CO, and a similar parallel can be drawn betweenthe spectra of NO and A.R.Mecke 41 has observed that the terms in the hydride spectraof Zn, Cd, and Hg (Le., of ZnH, CdH, and HgH) resemble the termsin the atomic spectra of the elements immediately preceding themin the Periodic Table. Such observations may finally prove avaluable guide to the structure of molecules.The analysis of a band spectrum already gives very variedinformation concerning the structure and behaviour of the moleculeresponsible for it. Pirst, it gives values for the moment of inertiaof the molecule, Le., for the distance between the atoms. Thespacing of the lines near the band origin is, very nearly, inverselyproportional to the value of I . Thus hydride spectra can oftenbe picked out by mere inspection, as I is very small, and the spacingunusually great.Secondly, the direction in which an electronicband is degraded indicates whether the atomic centres have movedtogether or become more widely separated as the result of theexpulsion of the electron to an outer orbit. Bands for which I’>Iare degraded towards the longer wave-length side, whilst if I’<Ithey are degraded towards the ultra-violet.The degree of stability of a molecule, again, may be indicatedby its spectrum. With the brief space available for the discussion2o H. Sponer, 2. Physik, 1925, 34, 622; A., 1926, 8.4o Physzccb~ Rev., 1925, [ii], 25, 291; A . , 1925, ii, 346; ibid., 1926, [ii],26, 561; 1926, [ii], 28, 481; A., 8, 1079.4 1 2. Phyeik, 1926, 36, 795; A., 667312 ANNUAL EEPORTS ON THE PROGRESS OF CHEMISTRY.of this point, it will perhaps be best to take a single example. Aband attributed to a molecule CaH occurs a t about A 3520, and hasbeen analysed into P and R branches.The intensity in each branchincreases smoothly up to na = 10 ; the band then suddenly ends.This behaviour is most readily explained by the supposition thatthe molecule cannot receive a further rotational energy quantumwithout di~sociating.~2 The absence of any associated bands inthe same spectral region similarly suggests that the moleculecannot take up even a single vibrational quantum without dis-sociation. Curtis 45 has suggested that the He, spectrum is limitedby similar considerations. A further discussion of the subject isgiven by H. Ludloff ,44The application of Saha’s theory to the prediction of the effectof temperature on atomic absorption spectra has been mentionedin a previous section.A similar effect would be predicted for mole-cules sufficiently stable to possess several ‘‘ excited ” electronicstates; i.e., a percentage of the molecules should pass from thenormal to the nearest excited state at sufficiently high temperatures,and new absorption bands should appear. This phenomenon hasbeen observed with oxygen. One set of bands is present in theultra-violet at the ordinary temperature, and others appear con-secutively as the temperature is raised.46The foregoing discussion has been limited to the spectra ofdiatomic molecules. Any more complex molecule must possessmore than one effective axis of rotation, and, in addition, thepossibilities of various vibrational and electronic changes alsorapidly increase.The study of the spectra of such moleculesbecomes correspondingly diEcult, although there are indicationsthat, as has so often happened before in spectroscopic matters, thephenomena are not so complicated as a &st pessimistic survey wouldpredict. V. Henri 46 has been engaged for some years on the experi-mental study of the absorption spectra of organic molecules, andhe has arrived a t several interesting generalisations. In additionto “ rotation ” and “ vibration-rotation ” spectra, the vapours ofmany substances exhibit ‘‘ electronic ” bands. Some of these lastbands have the ordinary band structure described above; othershave no fine structure, but are truly continuous over a range ofsay, 6-10 A.Finally, other bands of the same substance may becontinuous and 100 8. wide. Proceeding along the absorption(2 R. S. Rfulliken, Physical Rev., 1925, [ii], 25, 509; A., 1925, ii, 469.43 L O G . cit.4 3 C. Fuchtbauer and E. Holm, Physikal. Z., 1925, 26, 345; A . , 1925, ii,4 6 “ Structure des Molecules,” Pub. de la SOC. Chim. Phys., XII, Hermann,44 2. Physib, 1926, 39, 528.626.1925SPECTROSCOPY. 313spectrum from Iong to short wave-length, there is a universalorder for these types of bands : (1) fine-structure bands, (2) narrowcontinuous bands, (3) wide continuous bands, The interpretationset upon the narrow continuous bands, by Henri, is that the rota-tional energy of the molecule is not quantised during their pro-duction, whilst, to account for the bends 100 A, wide, it is suggestedthat for these neither the rotational nor the vibrational, but onlythe electronic, energy is quantised.Henri has also analysed manyof the fine-structure bands into their P, Q, and R branches, obtain-ing in this way the corresponding moments of inertia of the molecule.This method applied to the spectra of formaldehyde, acetone,carbonyl chloride, and other ‘’ Y-shaped ” molecules has led himto conclude 47 that such molecules behave as if symmetrical, withonly two effective moments of inertia, one about an axis along thestem of the Y and the other about a perpendicular axis.As a typical example of the spectra of organic substances, wemay take the naphthalene spectrum, which has recently beendescribed by V.Henri and H. G . de The absorptionspectrum contains five distinct regions-one in the infra-red(3.25-9.81 p), one in the visible (7140-6060 8.), and three in theultra-violet. Of these last three, the first (3192-2818 8.) consistsof bands with a h e structure, the second (2818-2000 8.) of con-tinuous bands 5-10 A. wide, and the third (below 2000 A.) ofbands 100 8. wide. These observations, it will be noted, are inagreement with the generalisations just mentioned. Henri deducesfrom these facts that there are four “ excited ” electronic states ofthe naphthalene molecule, which we may call E l , E,, E,, and E,,the “normal” state being E,. The infra-red absorption bandsare regarded as vibration-rotation bands only, whilst the otherfour groups represent excitation to the four ‘‘ excited ) ’ states.The supposition is supported by observations on the fluorescenceand cathodo-luminescence spectra of the same molecule. I nposition and structure, the former corresponds exactly to thetransitions E,-E, and E2-E,, and the latter to E,-E, andE,--E,.The heads of the bands with fine structure (E2-ICo)agree with the formula v = 32485.4 + 474.4 n + 203.4 p + 62.6 q,in which n, p, and q have integral values, say + 4 to - 4. Thepositions of the heads are fixed by the vibrational frequencies, aswe have seen, and for a diatomic molecule one of the variable termswould suffice. Here there are three, and it is concluded that thereare three characteristic vibration frequencies of the naphthalenemolecule concerned in the production of these bands.47 V.Henri and S. A. Schofi, C’ompt. Tend., 1926, 182, 1612; A,, 714.48 Proc. Roy. SOC., 1924, [ A ] , 106, 662; A . , 1924, ii, 613314 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Spectroscopic Analysis.In the first rush of spectroscopic discovery, the early workersin this field must have expected qualitative and quantitativeanalysis to be revolutionised by the new methods. Such hopeshave not been realised. The spectroscope is called in as an occasionalally of the conventional chemical procedure, but in spite of a. vastlyincreased range of instruments, and equally important improve-ments in technique, its application-except for a very few industrialuses-is still by no means widespread.There are, however,potentialities in spectroscopic analysis which have not been fullyappreciated in recent years, owing perhaps to the general pre-occupation with the physical side of spectroscopy.Qualitative Analysis.-This side of the subject will be dismissedvery briefly. The importance of the method lies in its rapidityand the certainty of detection of many elements, including mostmetals. Unfortunately, the sensitivity, so great for some elements,is by no means maintained for all, whilst others, notably C1, Br, I,0, N, S, and Se, are difficult to detect a t all by the usual spectro-scopic procedure, although special methods could doubtless bedeveloped. Since spectroscopic literature has become less chaotic,and trustworthy tables are now available for the identification oflines, the importance of this application is likely to increase.Itsremarkable sensitivity is well illustrated by A. de Gramont’s recentdiscovery that zinc is a constituent of all animal organisms.@The progress of a qualibative analysis is as follows. The materialto be examined is introduced into an arc, or into a condensedsparkJ5’J and the spectrum photographed, generally over the aave-length range 7000-2000 if., for which a spectrograph with a quartztrain is required. A comparison spectrum,51 often that of theiron arc or the gold spark, is cast upon the same plate. The wave-lengths of the lines from the unknown material can then be foundby micrometer measurements on the plate. When their wave-lengths have been obtained, the lines have to be identified withknown spectra, For this purpose, tables 52 are required of themore important lines of the elements, arranged in order of wave-length, and irrespective of origin,Raies U1timee.--In the detection of traces of an element by the&” For a description of the apparatus, see papers quoted below, and F.Lome, “ Optisohe Messungen,” Steinkopff, 1925.61 Tables of lines in such comparison spectra are given in Kayser’s “ Hand-buoh der Spectroscopic,” Vols.V, VI, and VII, and in Twyman’s ‘‘ Wave-length Tables,” Hilger, 1923.62 Kayser, “ Tabelle der Hauptlinien,” Springer 1920; Twyman, op. c d .Cornpt. rend., 1920, 170, 1037; .4., 1920, ii, 388SPECTROSCOPY.316foregoing method, there is a further point to be remembered.Two lines that are of equal intensity in an ordinary spectrum maybe very unequal when the element is present only in small quantity,and the line8 which persist a t the greatest dilution may be compara-tively inconspicuous in the spectrum from a. richer material. Thisfact was appreciated &st by W. N. Hartley in 1884. He arrangedthe lines of many elements in the order of their ‘( persistency.”More recently, de Gramont 53 has studied the same problem.Lines persisting in the spectrum, with very small quantities of theelement present, he called “raies sensibles,” and the last to dis-appear “raies ultimes.” The latter, he also observed, are notalways prominent in the full spectrum from an undiluted material.The selection of these sensitive lines by Hartley and de Gramontwas effected quite empirically, but modern theory has shown thattheir choice has a definite and important physical basis.The“ persistent lines,” “ raies ultimes,” and the closely analogous“long lines” of Lockyer are lines which are emitted during thereturn of electrons from some of the inner “ excited states ” to theinnermost or “normal” state of the atom. They are thereforenearly related t o - a n d are often identical with-the resonancelines of the elements.This subject has been discussed by 0. Laporte and W. F.Meggers 54 with the following conclusions. “ Raies ultimes ” arecombinations of the lowest term with the first higher non-meta-$,table term of the same series system; resonance lines are com-binations of the lowest term with a term of the highest multiplicitybelonging to the atom.If, therefore, the lowest term is one of themaximum multiplicity, the “ raie ultime ” and the resonance linewill be the same.55 Both neutral and ionised atoms provide “ raiesultimes ” ; thus those listed by de Gramont for calcium are 3933,3968, and 4227. The fist two are due to the singly ionised calciumatom, and the third is from the neutral atom.Quantitative Amly~is.-~4pplications of spectroscopic observationsto quantitative analysis have proved slow in development. Whatis needed for such purposes is some spectroscopic quantity whichvaries in a determinable manner with the proportion of an elementpresent in the sample under examination. Such a quantity,63 There is 8 long series of papers by A.de Gramont on this subject in theCompt. r e d . and elsewhere, beginning in 1907. See especially Compt. rend.,1920, 171, 1106; A . , 1921, ii, 73. A bibliography to 1923 and a list oflines are given by Twyman, o p . cit.6 4 J. 0p.L 8 0 c . Amer., 1925, 11, 459; A,, 1926, 216.6 5 See elso A. de Gramont, Compt. rend., 1922, 176, 1025; A., 1923, ii,517; W. I?. Meggers and C. C. Kiess, J. Opt. SOC. Amer., 1924, 9, 372; H. N.Russell, A6trOphY6. J., 1925, 61, 223316 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.unfortunately, is not easy to find, and although several proposalshave been made, the ideal solution is still lacking.The followingvariables have all been suggested : the intensity of the lines of theelement in question, the number of the lines visible, the “ length ”of the lines in a spark, and the time taken for the lines of a volatileelement to disappear from the spectrum.56 The ideal generalmethod of solving this problem would be the determination of theintensities of the characteristic lines of an element produced by aspecimen when subjected $0 some standard excitation. This pro-cess is impracticable for several reasons. Accurate spectral-intensitydeterminations, although they can now be done, are still dispro-portionately difficult. Also there is no known law connecting theintensity of a line with the percentage of the corresponding elementpresent in the specimen.Several more indirect methods have beenproposed from time to time, and a t least one of these has considerablepossibilities. The first important proposal was that of N. L~ckyer,~’who observed that the ( ( length )’ of a spectrum line in the spark(Le., the distance from the pole through which it spreads along thespark-gap) decreases with the proportion of the correspondingelement. A comparison of the length of lines from an unknownmaterial with the lengths of the same lines from EL series of standardsof known composition enabled him to make satisfactory quantitativeanalyses of alloys. The method is obviously too cumbrous for use.A better method was introduced by W. N. Hartley, who discovered,as stated above, that when the quantity of any element present ina material is gradually diminished to a very small value, lines duet o that element successively disappear from the resulting spectrum,until only a few are left.Working with solutions of salts, he,and, later, Leonard and Pollolr, tabulated the lines still observablewith decreasing percentages of metal present (1.0, 0.1, 0.01, and0.001%). By comparison of a spectrogram with these tables 58they obtained upper and lower limits for the percentage of anyelement present. This method is very circumscribed, and theresults may perhaps be described as “ semi-quantitative,” but itstill serves to give a rapid indication of the proportion of anymetal that may be present.A third procedure-and the most satisfactory-has beendeveloped by de Gramont 69 and a t the Bureau of Standards byW.F. Meggers, C . C. Kiess, and F. J. Stimson.60 The principle is335; for the determination of lead in copper.6 5 C. W. Hill and G. P. Luckey, Trans. Amer. Electrochem. Soc., 1917, 32,6 7 Phil. I‘rana., 1874, 164, 479. )* Reproduced by Twyman, op. cit.5# Ann. Chim., 1909, [viii], 17, 437; 1916, [ix], 3, 269; A,, 1915, ii, 499.60 Bull. Bureau of Standards, 1922, 18, 2 3 5 ; Sci. Paper, NO. 444; A.,1923, ii, 81SPECTROSCOPY. 317to compare the intenaity of lines in a spectrogram from the materialunder examination with their intensities in a series of spectrogramstaken under the same conditions from materials of known com-position, An illustration may be supplied from the paper quoted.This investigation was concerned with the analysis of alloys inwhich one element predominated. A very pure sample of thiselement was first obtained, and was used in the preparation ofseveral graded series of alloys, each aeries containing one of themetals, suspected as present in the primary alloy, in the proportions0.001, 0.01, 0.1, 1.0, and 10.0% (sometimes intermediate com-positions as well).These alloys were introduced as the poles of acondensed-spark apparatus, and their spectra were successivelyphotographed. The spectrum of the alloy under analysis was thentaken with the same apparatus. By matching intensities in thislast plate with those in the standards, the analysis was effected.The following table will serve as an indication of the accuracyachieved in this way.The alloys analysed were samples of boiler-plug tin.Spectrographic. Chemical.7 --- ,---------'-,Cu. Pb. Be. Zn. Ni. Cu. Pb. Fe. Zn.NO. 1. 0.1 0.1' 0.005 0.001 0.001 0.08 0.10 0.03 -NO. 3.* 0.8 0.6 0.02 0.04 0.01 0.76 0.63 0.02 -NO. 4.* 0.6 1.0 0.01 0.15 0.01 0.65 0.98 0.042 -NO. 2. 0.6 0.06 0.1 0.07 0.001 0.62 0.04 0.04 0.06* Theee samples also showed spectrographically, Ag 0~001, Bi 0.01:;.Analyses were made in the Aame way of gold used in the XanFrancisco mint, and of samples of platinum metals.Such results leave no doubts of the feasibility of quantitativespectrographic analysis. The necessities for its success are the useof a standard form of apparatus, constant observing conditions,and the careful preparation of a series of comparison samples.Inprecision, the results, for the constituents present only in smallquantity, must often surpass those obtained by gravimetric methods.It is precisely for such determinations, into which the manipulationof abnormally small precipitates, etc., must enter, that the normalmethods become unsatisfactory. The spectroscope, as the abovetable shows, easily distinguishes between chemically similar elementswhich require a highly complex " wet " separation. The time takenin making a spectrographic analysis, once the standard plateshave been prepared, is small in comparison with that consumed bythe ordinary methods. The spectroscopic methods clearly have agreater attraction for chemists faced with a long series of routineanalyses. Such restricted demands have been made upon th318 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.methods that their limitations in many directions are still uncer-tain.There are, however, several papers by de Gramont dealingwith applications, in addition to those to which reference hasalready been made. One of these 61 discusses the quantitativeanalysis of steels, and another contains an interesting summary ofthe uses of spectroscopy during the 'CVar.62 Reference may alsobe made to a paper by C. A~er-Welsbach,~~ and to one by S. JuddLewis 64 on the determination of nickel in fats.The foregoing account has by no means exhausted the quantitativeapplications of the spectroscope. It is difficult, as we have seen,to make a complex molecule emit a characteristic emission spectrum,but such molecules usually possess well-marked absorption spectra,and these have been used in a variety of ways for the estimationof the corresponding compound.The well-known band spectrumof nitrogen peroxide, for example, has served for the estimation ofthe gas,es utilising the same principle as that employed for emissionspectra by de Gramont, Meggers, etc., L e . , comparison with a seriesof standard plates. The use of a spectrophotometer would renderunnecessary this tedious preparation of standards. Many sub-stances which are colourless, and therefore cannot be determined" colorimetrically," have an absorption band in the ultra-violet,and so can be estimated by these methods.Finally, reference may be made to an ingenious method ofestimating carboxyhemoglobin, due to H.Hartridge.66 Bothhemoglobin and carboxyhemoglobin have a narrow absorptionband in the green, but the two bands are not identical in position,although they overlap. Thus, if carbon monoxide is graduallyintroduced into a solution of haemoglobin, the band appears toshift gradually towards the red until saturation is complete and theposition of the carboxyhemoglobin band has been reached. Hart-ridge has shown that by measuring the shift it is possible to estimatethe carbon monoxide to within 1%. He has introduced an instru-m e n t t h e '' reversal spectroscope "-for the rapid measurement ofthis shift, The principle of this instrument cannot be given here,but may be found in the paper quoted above.The Auroral Spectrum.There are still three spectra of uncertain origin and of outstandingastrophysical interest.These originate, respeebively, in nebulae,81 Compt. rend., 1921, 173, 13; A . , 1921, ii, 474.$2 Bull. Officiel de la Direction des Rwherches et des Inventions, 1920,64 J. Soe. Chem. Ind., 1918, 35, 883.6 6 R. Robertson and S. S. Napper, J., 1907, 91, 781.8 6 Pmc. Roy. Roc., 1923, [A], 1053, 676; A., 1923, ii, 106.No. 9, 480. 63 Monatsh., 1923, 43, 387; A., 1923, ii, 247SPECTROSCOPY. 319in the solar corom, and in the aurora. In spite of the remarkablewave-length relationships observed by Nicholson, as early as 1912,in the first two spectra, we are still quite ignorant of the natureof the atoms+r molecules-which are responsible for them.Thethird problem, the origin of the auroral green line, promises to bemore tractable.The aurora typical of high latitudes is observed a t heights between90 and 470 km., and its spectrum shows the nitrogen bands, and aprominent green line a t about 5577 8. The night sky also showsa " chronic " aurora, not confined to high latitudes or to particulardays, but actually increasing in intensity, for example, from thenorth to the south of the British Isles. Lord Rayleigh6' hasphotographed the spectrum of the " chronic " aurora a t differentlatitudes, Rith exposures of the order of 100 hours, and he hasfound that the green line is very prominent, whilst the nitrogenbands do not appear a t all.The mystery is heightened by thefact that, according to theory, helium should be the main con-stituent of the atmosphere above 130 km., whereas the heliumlines are certainly absent from the auroral light. Many hypotheseshave been put forward concerning the origin of the famous greenline. geocoron-ium," one of the &st of these was the identification of the linewith a prominent krypton line. More accurate wave-length deter-minations disposed of this somewhat tame solution. Recently,several other views have been advanced, but before these aredescribed, an investigation may be mentioned which has, to a smallmeasure, limited the possibilities. The " chronic " aurora is farmore intense over parts of the United States than over England,and the intensity there was sufficient for Babcock68 to photo-graph the green line through a Fabry-Perot Qtalon, with a ten-hourexposure. This investigation gave the wave-length as 5577,350 8.with extreme certainty, and the width of the line as 0.035 8.,which is the Doppler width of a helium line a t 218' K. As hasbeen pointed out in an earlier section, this result merely fixes aminimum value for the molecular weight of the emitter. H. Bon-gards69 identiiied the green line with a line from the blue, orenhanced, spectrum of argon. This opinion was coupled with avery speculative hypothesis as t o the origin of the argon. Heconsidered that calcium nuclei are ejected from the sun and, intheir passage, either gain two electrons or lose an a-particle, andS n d y become argon atoms, radiating in the upper atmosphere.Passing over the suggestion of an ad hoc elementIbid., 1921, [A], 100, 367; 1922, [ A ] , 101, 124, 312.6 8 A8tTOphy8. J., 1923, 67, 209.69 Physikal. Z., 1923, 24, 279320 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.L. Vegard 70 obtained a remarkable phosphorescence spectrum bybombarding solid crystalline nitrogen with cathode rays. Thisspectrum contained broad bands in the green, one with a maximumin the neighbourhood of the auroral line. The bands, he found,became narrower as the size of the crystals diminished, and heput forward the view that 5577 was the limiting form of thisspectrum, with crystals of molecular dimensions, further supposingthat such crystals are present in the upper atmosphere. Thistheory has been strongly criticised on many grounds.71 Finallywe come to McLennan’s latest investigation of this question.72He has obtained a green line, of wave-length 5577.35 d., by electricalexcitation, first in helium containing a little oxygen, and, later,in pure oxygen alone. The line cannot yet be correlated withany of the recognised series spectra of oxygen, but, judging fromits Zeeman effect, it is of atomic and not of molecular origin. Theidentification of this line with the auroral one is by far the mostpromising solution of the problem that has been proposed. Theagreement between the wave-lengths is excellent, and the oxygenspectrum is not so rich in lines that a coincidence is probable. Someexplanation, of course, is still required of the prominence of thisparticular line in the aurora, and of the absence, or extreme faint-ness, of the ordinary oxygen spectrum. It must be admitted thatthe explanation of the spectroscopic phenomena of the aurora,even of the green line alone, is still pleasantly incomplete.S. BARUTT.‘O N&ure, 1924, 114, 716; A . , 1924, ii, 805; Compt. rend., 1925, 180, 1084;A , , 1925, ii, 474.7 1 E.g., J. C. McLennan and G. M. Shrum, Proc. Roy. Soc., 1924, [ A ] , 106,138; A., 1924, ii, 642; and R. d’E. Atkinson, ibid., 1924, [ A ] , 106, 429.72 J. C. McLennan and G. M. Shrum, Pmc. Roy. Sac., 1925, [ A ] , 108, 501;A . , 1925, ii, 723; J. C. McLennan, J. H. McLeod, and W. C. McQuarrie,Nature, 1926, 118, 441; A,, 985

ISSN:0365-6217    

DOI:10.1039/AR9262300296

出版商:RSC    

年代:1926

数据来源: RSC