摘要:

ANNUAL REPORTSON TEEPROGRESS OF CHEMISTRYANNUAL REPORTSRI. P. APPLEBEY, M.A., E.Sc.H. BASSETT, D.Sc., Ph.D.H. V. A. RRISCOE, D.Sc.W. M. CUMMING, D.Sc.E’. G. DONNAN, C.B.E., M.A., F.R.S.H. W. DUDLEY, O.B.E., AI.Sc., P1i.L).J. J. Fox, O.E.E., DSc.C. S. GIBSON, O.H.E., 1I.A.R. W. GRAY, O.B.E., Ph.D., F.R.S.A. J. GREENAWAY, F.I.C.C. K. INGOLD, D.Sc., F.R.S.J. KENYON, D.Sc.U. It. EVAXS, M.A.T. A. HENRY, D.Sc.ON THEH. KING, D.Sc.T. S. MOORE, M.A., 13.S~.G. 1’. MORGAN, O.H.E., D.Sc., F.R.S.I<. J. Y. ORTON, M.A., F.R.S.J. R. PARTINGTON, M.B.E., D.Sc.J. C. PUILIP, O.B.E., D.Sc., F.R.S.F. L. PYMAN, D.Sc., P.R.S.R. I<, RIDEAL, M.A., P1i.I).K. ROBINSON, D.Sc., F.R.S.d. F. THORPE, O.B.E., D.Sc., F.H.S.‘r. s. PRICE, o.B.E., D.SC., F.R.S., ,L I,.SIBIONSEN, I).Sc.’ 5. SUGI)gh, asC.PROGRESS OF CHEMISTRYJ. D. BEKNAL, 3l.A.A. J. BRADLEY, P1i.D.W. L. BRAGO, M.A., F.R.S.H. V. A. BKISCOE, D.Sc.A. C. CEIBNALL, M.A., Ph.D.B. A. ELLIS, M.A.J. J. Fox, O.B.E., D.Sc.W. N. HAWORTH, D.Sc., Ph.D., F.R.S.E. L. HIRST, M.A., Ph.D.FOR 1928.H. HUNTER, D.Sc.C. K. INGOLI), D.Sc., F.R.S.It. W. JAMES, M.A.S. G. P. PLANT, D.Ph., M.A.J. PRYDE, bi.Sc.E. K. RIDEAL, M.A., Ph.D.P. L. ROBINSON, D.Sc.A. S. RUSSELL, M.C., M.A., D.Sc.0. H. WANBBBOUCH-JONES.ISSUED BY THE CHEMICAL SOCIETY,VOl. xxv.LONDON :T H E C H E M I C A L SOCIETY1929PRINTED IN GREAT BRITAIN RYRICHARD CLAY & SONS, IdMITED,BUNGAY, SUFFOLKCONTENTS.PAOEGENERAL AND PHYSICAL CHEMISTRY.By H. HUSTER, D.Sc. . 11INORGANIC CHEMISTRY. By H. V. A. BRISCOE, D.Sc., and P. L.ROBINSON, D.Sc. . . . . . . . . . 36ORGANIC CHEMISTRY :-Part ~.-ALIPHATIC DIVISION. By W. N. HAwoRrrI, D.Sc., Ph.D.,F.R.S., and E. L. KIRST, M.A., Ph.D. . . . . . 67Part II.-HOMOCYCLIC DIVISION. By C. K. INGOLD, D.Sc., F.RS. . 111163 Part III.-HETEROCYCLIC DIVISION. By S. G. P. PLANT, D.Ph., M.A.ANALYTICAL CHEMISTRY. By B. A. ELLIS, M.A., and J. J. Fox,O.B.E., D.Sc. . . . . . . . . . . 198BIOCHEMISTRY. By A. C. CHIBNALL, BLA., Ph.D., and J. PRYDE,M.Sc. . . . . . . . . . . . 222CRYSTALLOGRAPHY. By W. L. BRACG, M.A., F.R.S., R. W. JAMES,M.A., J. D. BERNAL, M.A., and A. J. BRADLEY, Ph.D. . . 276SUB-ATOMIC PHENOMENA AND RADIOACTJVITY. By A. S. RUSSELL,K C ., M.A., D.Sc. . . . . . . . . . 303CATALE'SIS. By E. K. RIDEAL, M.A., Ph.D., and 0. H. WANSBROUGH-JUNES . . . . . . . . . . . 32TABLE OF ABBREVIATIONS EMPLOYED IN THEAbbreviated Title.A . . . . .A , . . . . Amer. Chcm. J . . .Awwr. J. Phmn. .Amer. J. Sci. . .Anal. Fis. &uim .Analyst . . . Annalen . . .A m . Acad. 9ci. FennieacAnn. Bot. . . .Ann. Chim. . .Ann. Chim anal. .Ann. Chirn. A w l . .Ann. Phyaik . .Aim. Physiqqie . .Ann. Rcports . .Arch. Phrm. . .Arch. Sci. phys. nut. .A ~ k i v Xem. Min. Geol.A ~ l ~ q p h p . J. . .Alti 11. Accad. Lincei .Apth.-Ztg. . .B . . . . .Ber. . . .Ber. Siichs. Ges. CVis’iSs.Biochtrn. J. . ,Biochm. 2. . .Boll. Chim. farm. .Brit. Aseoc. Reports .Bul. SOC.chim. Rol,tdniaB.ulZ. A&. roy. Belg.REFERENCES.FULL TITLE,Abstracts in Journal of the Chemical Society.British Clietnical Abstracts,* Section A.American Chemical Journal.Ameriuan Journal of Pharmacy.American Journal of Science.Anales de la Sociedad Espancla Fisica y Quimica.The Analyst.Justus Liebig’s Annalen der Chemie.Annales Academia Scientiarum Fennicae.Annals of Botany.Annales de Chimie.Annales de Chimie analyti ue appliquie h l’Indu&trie,Annali di Chimica Applicata.Annalen der Physik.Annales de Physique.Annual Reports of the Chemical Society.Apotheker-Zeitung.Archiv der Phannazie.Archives des Sciences physiqnes et naturelles.Arkiv for Kemi, Mineralogi och Geologi.Astrophysical Journal.Atti (Kendiconti, Memorie) della Reale AcademiaNazionale dei Lincei, classe di scienze hiclie,matematiche e naturali, Roma.British Chemical Abstracts,* Section B.Berichte der Deutschen Chemischen Gesellechaft.Berichte uber die Verhandlungen der KoniglichSiichsiscben Gesellschaft der Wissenachaften(math.-phys. Klasse).The Biochemical Journal.Biochemiache Zeitschrift.Bolletino Chimico farmaceutico.Report8 of the British Association for the Advance-Buletinul Societiitei de Chimie din RomQnia.A l’Agriculture, h la Plarmacie et P la Riologie.ment of Science.. Acadkmie royale de Belgique-Bulletin de la ClaeseBull. Chem. Soc. Japan . Bulletin of the-Chemical Society of Japan,B d l . Inst. Phys. Chem. Res. Bulletin of the Institute of Physical and ChemicalTokyo .. . . Research, Tokyo.Bull. Soc. chim. . . Bulletin. de la Sociktd chimique de France.Bull. Soc. chim. Belg. . Bulletin de la SociBtR chimique de Bel$que.Bull. Soc. Chim. bioZ. . Bulletin de la SociBtB de Chimie biologpque.des Sciences,The year is not inserted in references to 1928viii TABLE OF ABBREVIATIONS EMPLOYED IN THE REFEREN~ES.A6brevidtw.i Title.Celluloseehem. . . .Chem. Lhty . . .C h . News w , .C h . Reviews . .C h . Weekbtad' . .Chcm. Zentr. . . .Cium.-Z&g. . . .Chim. et Ind. , . .Chinese J. Physiol. . .Compt. rend. . . .Compt. rend. Trav. Lab.D.S.I.R., €€.M,*Stat.' O&Dansk Tidsskr. Fawn. .Dmt. meti?. Wochenschr. ,Fernt-cnlforsch. . . .Gazutta . . . . oi-. mim. rnd. A ~ Z . .HeEv.Chim. Acta . .Ind. Eng. Chcm.. . .Indian J. Physics . .J. . . . .J. Agric. Rks. . . .J. Agric. Sci. . , .J. AM. Chem. Soc. . ,J. Amer. Med. Assoc.. .J. Anzer. Water WorksAssoc. . . . .J. Assoc. Of. Agric. Chcm.CarlsbergJ. BioE. Chein. . .J. Chain. Ind. MoscowJ. Chim. phys. . .J. Franklin Inst. ..I Gen. Physwl. . .J. Indian Chin. Soc. .J. Jndiun Imt. Sci. .J. Id. Hygiene . .J. Inst. Mctals . .J. Pharm. Chim. .J. Pharm. Bxp. Ther.J. Physical Chem. .J. Physwl . . .J. Physique. . . .J. Russ. Phys. Chcm. Sm. .J. S. African Chew Inst. .J. Soc. Chcm. lnd. . .J. SOC. Chem. Ind. Japan .J. SOC. Chem. Japan , .KgZ. Damkc Videnskap.SehJc. rnath.-fys. Me&. .J . p . Chcm. . . .FULL TITLE.Cellulosechemie.Chemickd Lists pro V4du a PrSmysl.Organ de la" CeskB chemickh Spolednost pro Vcidu aPrflniysl. 'IChemical News.Chemical Reviews.Chemisch Weekblad.Chemisches Zentralblatt.Chemiker- Zeitung.Chimie et Industrie.Chinese Journal of Physiology.Corn tes rendua hebdomadaires des SOances deCorn tes rendus des Travaux du Laboratoire Carls-Department of Scientific and Industrial Research,Dansk Tidsskrift for Farmaci.Deutsche medizinische Wochenschrift.Fermentforschung.Gazzetta chimica italiana.Giornale di Chimica Industriale ed Applicata.Helvetics Chimica Acta.Industrial and Engineering Chemistry.Indian Journal of Physics.Journal of the Chemical Society.Journal of Agricultuid Research.Journal of Agricultural Science.Journal of the American Chemical Society.Journal of the American Mediral Association.Journal of the American Water Works Asnociation.Journal of the Association of 05cial AgriculturalJournal of Biological Chemistry.Journal of Chemical Industry, Moscow.Journal de Chimie physique.Journal of the Franklin Institute.Journal of General Physiology.Quarterly Journal of the Indian Chemical Society.Journal of the Indian Institute of Science.Journal of lnduatriol Hygiene.Journal of the Institute of Metals.Journal do Pharmacie et de Chimie.Journal of Pharmacology and Experimental Thera-Journal of Physical Chemistry.Journal of Physiology.Jouriial de Physique.Journal fur praktische Chemio.Journal of the Pliysical and Chemical Society ofJournal of the South African Chemical Institute.Journal of the Society of Chemical Industry.Journal of the Society of Chemical Industry, Japan.Journal of the Chemical Society of Japan.(NipponKongelige Danske Videnskapernens Selskab, mathe-P' Acaddmie des Sciences.!erg.His Majesty's Stationery Office.Chemists.peutics.Rmsia.(IGgyij Kwagaku Zasshi.)Kwagnku Kwai Shi.)matisk-fyaiske MeddelelserTABLE OF ABBREVIATIONS EMPLOYED IN THE REFERENCES. ixAbbreviated Title.Me&. K. Yetenskapsnkad.Nobel-Inst. . . .Xem. Coll. Sci. Kyoto. .Mein. Munchester Phil. SOC.Mikrochem. . . .Min. Mag. . . . .Monatsh. . . . .Nach. Ges. Wiss. Gottingcn.Naturwiss. . .Natuurzoetemch. TGds.Neue Jahrb. H i 7 a .Norsk Qeol. TidsskriftNorsk. Yid. Akad..Notiz. china. -id.Pharm. Zentr. . .Phil. Mag. . .Phil. Trans. . .PhysicaE Rev. . .PhysikaE. 2. . .Physiol. Abs. . .Physiol. IZeviews. .Plant Physwl. . .Proc. Am&. Acad. Arts Sci.Proc. Casib. Phil. SOC. .Proc. Imp. Acad. Tokyo .Proc. Indiana Acud. 8ci. .Proc. lndiana Chcm. S‘oc. .Proc. Iowa Acad. Sci. .Proc. K. Akad. Wetcnsch.Proc. Nnt. Acad. Sci. . .Proc. Nova Scotia Inst. Sci.Proc. Roy. SOC. . . .Proc. Roy. SOC. New SouthW a h . . . .Proc. SOC. Exp. Biol. Med. .Pub. Pac. Sci. Univ. JfasarrjkAmsterdamRec. trav. chim. . . .Rev. gdn. Colloid. . .Roca Chm. . . .Say. Papers Inst. Phys.Ckm. Res. Tokyo . .Sci. Rep. Tdhoku Imp. Univ.Sitzzcngsber. Preuss. Akad.Wiss. Berlin . . .Skand. Arch. Physiol. .FULL TITLE.Meddelanden frLn l<unglig-~etenskapsaliademjensMemoirs of the College of Science, Kyoto ImperialMemoirs and Proceedings of the Manchester LiteraryMikrochemie.Mineralogical Magazine and Journal of the Minera-Monatshefte fur Cheinie und verwandte Theile andererNachrichten von der Gesellschaft der WissenschaftenDie Naturwissenschaften., ,..Natuurwe tenschappelijk 1 Ijdschrift.Neue Jahrbuch fur Mineralogie.Norsk Geologisk Tidsskrift, Oslo.Skrifter utgitt av det Norske Videnskaps-Akademi iNotiziario chimico-industriale.Pharmazentische Zentralhalle.Philosophical Magazine (The London, Edinburgh andDublin).Philosophical Transactions of the Royal Society ofLondon.Physical Review.Physikalische Zeitschrift.Physiological Abstracts.Physiological Reviews.Plant Physiology.Proceediiigs of the American Academy of Arts andSciences.Proceedings of the Cambridge Philosophical Society.Proceedings of the Imperial Academy of Japan.Proceedings of the Iiidiana Academy of Sciences.Proceedings of the Indiana Chemical Society.Proceedings of the Iowa Academy of Science.Koninklijke Akadeniie van Wetenschappen te Amster-dam.Proceedings (English version).Proceedings of the National Academy of Sciences.Proceedings of the Nova Scotia Institute of Science.Proceedings of the Royal Society,Proceedings of the Royal Society of New SouthNobel-Institut.University .and Philosophical Society.logical Society.Wissenschaften.zu Gottingen.Oslo. I, Matem. -Naturvid.Klasse.Wales.Proceedings of the Society for Experimental BiologyPublications de la Facultk des Sciences de l’Universitt5and Medicine.Masaryk (Spisy vydavanb Prirodovhdeckon Fa-coulton Masarykovy University).RecueiI des travaux cliimiqnes des Pays-Bas et de laBelgique.Revue gherale des Colloides.Roczniki Chemji organ Polskiego TowarzystwaChemicznego.Scientific Papers of the Tnstitute of Physical andChemical Research, Tokyo.Science Reports, TBhoku Imperial University.Sitzungsberichte der Preussischen Akademie derWissenschaften zu Berlin.Skandinavisches Archiv fur Physiologie.AX TABLE OF ABBREVIATIONS EMPLOYED IN THE REFERZNCES.Abbreviated Title.Tram. Amer. Electrochem.SOC. . . .Trans. Faraday Soc. . .Trans. Roy. 8oc. Canada .Fkraine Chem. J. . .U. S. Pub. Health Rep. .Wiss. Verof. Siemens-Konx.Z. anal. Chem. . , .Z. angew. Chm.. . .Z. anorg. Chem. . . .z. BWl. . . . .Z. Elektrochnz. . . .Z.Krist. . . . .Z. Metallk. . . . .Z. Physik . . . .2. physikal. Chem. . .Z. physwl. Chcm. . .Zentr. Min. #ml. . .FULL TITLE.Transactions of the American ElectrochemicalTransactions of the Faraday Society.Transactions of the Royal Society of Canada.Ukrainian Chemical Jonrnal.United States Public Health Reports.Wissenschaftliche Veroffentlichungen aus demZeitschrift fur analytische Chemie.Zeitschrift fur angewandte Chemie.Zeitschrift fur anorganische und allgemeine Chemie.Zeitschrift fur Biologie.Zeitschrift fur Elektrochemie.Zeitschrift fiir Krystallographie.Zeitschrift fur Metallkunde.Zeitschrift fiir Physik.Zeitschrift fur physikalische Chemie, StochiometrieHoype-Seyler’s Zeitschrift fur physiologische Chemie.Zentralblatt fur Mineralogie, Geologie, und PalLon-Society.Siemens - K on zern.und Verwandtachaftslehre.tologie

ISSN:0365-6217    

DOI:10.1039/AR9282500001

出版商:RSC    

年代:1928

数据来源: RSC

摘要:

X TABLE OF ABBREVIATIONS EMPLOYED IN THE REFERZNCES.ERRATA.VOL. XXIV, 1927.Page, Line.151 7* for “(I, n)” read “(I, +).”151 6* for “(T, -+)” r e d “(T, n).”354 4 for “Subramanian, V., 221, 223” read “Snbrahmanyan, V.,221. Subramaniam, V., 223.”* From bottom

ISSN:0365-6217    

DOI:10.1039/AR9282500010

出版商:RSC    

年代:1928

数据来源: RSC

摘要:

ANNUAL REPORTSON THEPROGRESS OF CHEMISTRY.GENERAL AND PHYSICAL CHEMISTRY.THE large output of research in this branch of the subject has beenmaintained and, in accordance with the practice of previous years,this Report is confined to a few topics which have been brought intoprominence during the year and have not been reported upon forsome time.Injra-red Spectroscopy.Four important papers 1 on this subject have been published bySir R. Robertson and J. J. Fox (one of them in collaboration withE. S. Hiscocks). The first part of the investigation consisted ofan elaborate study of the conditions necessary for ensuring successin the work, the object of which was to measure the infra-redabsorption of ammonia, phosphine, and arsine. The source ofenergy employed was a Nernst filament, backed by a concavemirror and enclosed in an asbestos housing.It was supplied with acurrent of 1 amp. at 110 volts from a battery of accumulators, asthe supply from the mains was not sufficiently steady. An accountis given of the difficulties encountered and the masterly way in whichthey were overcome : the calibration of the spectrometer, correctalinement of the observation tubes, electromagnetic and mechanicalshielding of the galvanometer, and the method of attachment of theleads were all very carefully carried out in order to ensure highaccuracy of the results. The care expended on this part of the workis made evident by the fact that the bismuth-silver 20-junctionthermopile was shielded to protect it from the effect of adiabaticcompression of the air of the laboratory, e.g., by the sudden closingof a door.The method of observation used for the most part in theseinvestigations was to bring alternately into the optical path twotubes, the one containing gas and the other gas-free.This resulted1 PTOC. Roy. SOC., 1928, [ A ] , 120, 128, 141, 161, 189; A,, 107322 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.in speedier and more accurate working than the alternative methodof using one tube only and evacuating it to determine the emissionof the Nernst filament. Two tubes, 100 and 450 mm. long, wereemployed, according as strong or weak bands were being explored.Interesting details are given for the calibration of the wave-lengthdrum of the spectrometer for prisms of rock-salt, quartz, andfluorite, and special care was taken to allow for the effect of temper-ature on the refractive indices of these materials.2 The gases usedwere prepared with the utmost regard for purity.The resolutioneffected was not sufficient to show fine structure below 2.2 p withthe quartz prism : bands were partly resolved from 2.2 p (quartz),4 p (fluorite), and 5 p (rock-salt), and the fine structure was revealedin the bands above 3 p (quartz), 6 p (fluorite), and 8 p (rock-salt).In the case of unresolved bands, the centre near the peak was takenas the oscillation frequency. The partly resolved bands show threepeaks, of which the centre one was taken as the oscillation fre-quency, the side peaks also being evaluated.In the case of thefully resolved bands, the positions of the rotation maxima imposedon the oscillation band are given. The results are calculated interms of percentage absorption against wave number, and thespectra of the three compounds are compared.Ammonia has the most complicated spectrum, but all threegases have in common a main sequence of harmonic bands (I, 11,. . . V or VI), ammonia has a second sequence (C, D, . . .) notpresent in phosphine or arsine, a faint sequence (a, b, . . .), andbands at 4.05 and 10.55 p. Phosphine and arsine have also asecond sequence (A‘, B’, . . . and A”, B”, . . .) and a sequence(a, p, . . .) not present in ammonia. The main bands I-VI arenearly in harmonic sequence and their intensity in general decreasestowards the visible region of the spectrum.These bands are allof the same type characterised by an intense zero (Q) branch withless intense side branches (P and R). The ammonia band a t10-55 p has the unique feature of possessing two Q branches closetogether. Beer’s law ( I = I,,E-~~) is obeyed for all the gases atlower pressures in the case of the fine structure bands, but deviationsoccur, particularly at atmospheric pressure, and these are, nodoubt, connected with the fusion of the bands.Nearly constant ratios are found to exist between the vibrationnumbers of the members of the main sequence common to thethree gases, and the second sequence (A’, B’, etc.) in phosphineand arsine has a common ratio similar to that in the main series.There are thus certain degrees of freedom common to the threegases.The molecular moments of inertia for the three compoundsAnn. Reports, 1927, 24, 14GENERAL AND PHYSICAL CHEMISTRY. 13are calculated from the mean spacing differences determined fromthe fine structure of some of the bands, and are compared with thevalues given by the classical energy relation for three degrees offreedom in the following table :J~ x 1040 (c.g.s.1 J , x 1 0 4 0 (c.g.s.1from band structure. from energy relation. J , / J l .NH, ............ 2-78 3-49 1.26PH, ............ 4.78 6.24 1-30ASH, ............ 5-83 or 6-51 8-28 1.27 or 1.49The fairly constant ratio in the last column indicates that the factorused with kT in the classical equation should be less than 3/2.The results may be taken to support a tetrahedral model for themolecule of ammonia, but appear to indicate that the oscillationsare greater in number than can be accounted for by considerationof valency bonds alone.If the molecule of ammonia be consideredas a tetrahedron (and it is unnecessary to place the nitrogen atomat any great distance from the plane of the hydrogen atoms), thereappear to be six possible modes of vibration : (1) nitrogen againstthe plane of the hydrogen atoms (i.e., along a line directed towardsthe centre of gravity of the model), (2) nitrogen against one hydrogenatom, (3) hydrogen perpendicular to a line joining it to the centreof gravity of the model, (4) nitrogen as in (3), (5) the moleculerotating about its centre of gravity, and (6) the molecule rotatingabout an axis through the line joining the nitrogen atomto the centre of gravity.Plane models are possible, but moredifficulties are encountered with these than with the tetrahedralmodel. These considerations apply likewise to phosphine andarsine. Work on the infra-red absorption of the N-H linking insubstituted ammonias has been carried out by J. W. Ellis and byE. Hulth$n and S. Nakamura.4A. A. Levin and C. F. Meyer 5 have studied the infra-red absorp-tion spectra of acetylene, ethylene, and ethane between 2 and 15 p.Each gas shows a characteristic structure for its vibrational-rotational bands. Acetylene shows three main absorption regionswhich were resolved into lines which are alternately intense andfaint, and have the same average spacing in the three bands.Themolecular moment of inertia of acetylene calculated from thespacing of the fine structure of the principal bands is in agreementwith that obtained from the classical theory of energy on theassumption of a linear molecular structure. Ethylene shows sevenJ . Amer. Chem. SOC., 1927, 49, 347; 1928,50, 685; A., 1927, 291; 1928,458.Nature, 1927, 119, 235; A., 1927, 185.5 Proc. N a t . Acad. Sci., 1927, 13, 298; A,, 1927, 918; J . Opt. SOC. Amer.,1928, 16, 137; A,, 67014 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.regions of absorption. Two of these lack Q branches, one shows astrong Q branch, and the other four show sharp Q branches togetherwith P and R branches.Ethane shows bands each consisting of asingle succession of absorption maxima. An expression for theshape of an infra-red absorption line has been developed by D. M.Dennison,'j who shows that the absorption coefficient may beexpressed by means of two damping curves involving the numberof molecules per unit volume, the temperature, and the effectivediameter of the molecule. The formulz are applied to the case ofhydrogen chloride, and a value of 10.8 x 10-8 cm. is obtained forits effective diameter. The infra-red emission spectrum of hydrogenhas been examined,' and 6 higher members of the Paschen serieswith wave-lengths in accordance with the Bohr theory have beenobserved.Rotatory Bispersion.An attempt has been made to decide the vexed question of thespatial configuration of optically active molecules by reference torotatory dispersion curves and temperature-rotation curves. Theauthors of this attempt reject as incomplete the view that anomalousrotatory dispersion is due to an infra-red rotatory electron and anultra-violet rotatory electron of the same sign,g and also the viewthat it is due to two ultra-violet rotatory electrons of opposite sign,loand have put forward the theory that it is due to " one or morerotations of electronic origin in the ultra-violet and a rotation ofmolecular origin, due to atomic oscillations, in the infra-red." Itis considered that the partial rotation due to the infra-red term,although small in the visible region, is of great importance, since,being of molecular origin, its sign is of necessity the same as thatof the molecular configuration.The conventions of nomenclaturehere are important : an infra-red term of hvorotatory molecularorigin will contribute a dextrorotatory dispersion to the rotatorypower, since the latter of necessity changes sign on crossing a band,and the visible and accessible region of the spectrum is on the high-frequency side of the infra-red band. Nevertheless-since thegreater part of the rotatory power in the region of the spectrumaccessible to experimental observation is due to the ultra-violetrotatory electron system which, owing to the fact that it absorbsenergy on the high-frequency side of the accessible region of thePkyerical Rev., 1928, [ii], 31, 603; A,, 571.A.H. Poetkar, ibid., 1927, [ii],, 30, 418; A., 1927, 1117; Nature, 1927,119, 123; A., 1927, 177.8 C. E. Wood and S. D. Nicholas, J . , 1928, 1671, 1696, 1712, 1727; C. E.Wood, A. E. Chrismen, and S. D. Nicholas, ihid., p. 2180.9 R. W. Wood, " Physical Optics," Macmillrtn, 1919 ed., p. 492.l o T. M. Lowry and It. 0. Cutter, J., 1926, 127, 604GENERAL AND PHYSICAL CHEMISTRY. 15spectrum, contributes a partial rotation of its own sign to the totalrotatory power-a molecular structure which contributes a laevorota-tory term (one of negative sign) to the dispersion equation is saidto possess a dextro-configuration. Various possible cases areconsidered, the initial treatment being similar to work alreadypublished11 except that, in this instance, the visible region of thespectrum lies between the absorption bands instead of on the low-frequency side of them.The authors accept the Drude equationas the basis of their theoretical arguments, and by considerationof one infra-red and two ultra-violet terms they are led to an inter-esting extension of existing theory when the ultra-violet terms areof opposite sign and the one of highest frequency has a sign oppositeto that of the infra-red term, i.e., when cc = kl/(h2 - 1;) - kz/(h2 -1;) - k3/(h2 - 1;) and A1<h,<A,. I n this case, the dispersioncurve can cross the axis only in one way, that is, when daldh hasthe same sign as the ultra-violet term of highest frequency. Whenthis occurs, the anomalies (maximum on the curve and point ofidexion) must of necessity lie in the region of rotatory power ofthis sign. This case is illustrated above, where the full curve EF11 Ann.Reports, 1924, 21, 316 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.is the sum of the partial rotations represented by the dottedcurves.Under these conditions, Lowry’s criterion for the limiting conditionfor anomaly l2 requires modification. Whereas, on the older view,El was required to be greater than E , when ll was less than A, foranomaly to occur, the present theory extends the region of variabilityof k, to include the case of its equality to k, withoutl causing thedisappearance of the anomaly, since the curve is made to cross theaxis even when it1 = k, by the influence of the infra-red term,however small this may be.If the influence of the infra-red termis large, of course, E2 may even appreciably exceed El withoutcausing the anomaly to disappear. It follows from this that in allcases of anomalous dispersion the sign of $he high-frequency term in theDrude equation is, regardless of its magnitude, opposite to that of theinfra-red term, and hence the same as that of the conJguration of themolecule. Reference to the sign of the infra-red term thus becomesnecessary for determining configuration only in cases of simpleand complex but not anomalous dispersion. The term “ simple ”is here applied to dispersions which require only one ultra-violetterm in the Drude equation.It is considered that the infra-red term in the dispersion equationis due to the atomic tetrahedron about the asymmetric carbonatom, and that the ultra-iriolet terms are due to much lighterelectronic tetrahedra similarly disposed. With eight electronsabout the carbon (or other) atom, two tetrahedra would be obtainedwhich, when displaced in opposite directions in response to lightwaves, would give rise to anomaly in the region between the nearultra-violet and the infra-red basic frequencies, and possibly in thevisible region ; when displaced in the same direction would give riseto complexity but not to anomaly; and when displaced in the samedirection and acting as a single tetrahedron, would give rise tosimplicity of rotatory dispersion.The above rule for determining configuration gives, when i t canbe applied, an absolute specification of configuration, and thus, forthe first time, configurations of unrelated compounds may becompared, but the assignment of absolute space formuke requires,in addition, a knowledge of the order of the deflexion of the fourgroups involved, and this is at present available only in the casesof homologous series and other classes of compound structurallyrelated by synthesis.Many cases of this kind are reviewed by theseinvestigators.When anomaly is present , information regarding configurationmay be obtained by a consideration of temperature-rotation curves.l2 Ann. Reports, 1914, 11, 15GENERAL AND PHYSICAL CHEMISTRY. 17After a detailed examination of the possible cases, these authorsarrive at this conclusion, amongst others ; that the configurationof a compound may be determined from a family of temperature-rotation curves by the following considerations : (a) the slope ofthe curve, da/dT, where it crosses the axis of zero rotation is positivefor a compound of d-configuration if the maxima on the curves areon the high-temperature side of the anomalous region, and ( b ) themaxima move from high to low temperatures as the wave-lengthincreases.These considerations are reversed if the region of anomalyis on the high-temperature side of the maxima, and the conditionsfor a compound of Z-configuration are, of course, mirror images ofthose for compounds of d-configuration.The validity of the Drude equation has been questioned byT.Bradshaw and G. H. Livens,13 who have applied an equation(previously derived by one of them 14) to the rotatory dispersionof quartz. by means of theequationwith = 0.010627; = 78-22 p2.His later, more accurate readings 16 between Ah 2.5170 and 0.2280 pcompelled him to modify his formula towith h: = 0.0127493 ; h.2 = 0.000974 p2 ;so that A, is now right down in the very short ultra-violet regionof the spectrum instead of in the long infra-red region, and theeffect of the infra-red term is replaced by a constant.Neither of these formulze, however, represents the results obtainedby J. Duclaux and P. Jeantet l7 for the region between hh 0.3086and 0.185398 p, and, furthermore, the constant term in Lowry'ssecond equation is improbable since i t cannot be reconciled withany theory of dispersion.Bradshaw and Livens have fitted allthese observations by means of the formulaLowry fitted his first series of dataa = A,/(h2 - 1:) -+ A2/(h2 - 1;) + A,/X2 . . (1)a = A,'/(P - 1:) + A2'/(A2 - A;) - A,'. . . (2)845.694 0-40235 838-4320 0.1331233 - - __1 2 - g- - (12 -a=12 - 1; (h2 - 1 y(3) A2 - 13" (12 - 13")Z * - - 43,05794 2 1 19.11 7 + +--where 1; = 0.01274912, 1; = 0.01208000, Xt = 80 p2, and a is indegrees per mm.l3 Proc. Roy. Soc., 1929, [ A ] , 122, 245.14 G. H. Livens, Phil. Mag., 1914, 27, 994.15 Phil. Trans., 1912, [ A ] , 212, 261.T. M. Lowry and W. R. C. Coode-Adams, ibid., 1927, [ A ] , 226, 391; A.,17 J . Ph,ysique, 1926, 7, 200; A., 1926, SS6.1927, 81318 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.This formula fits the latest of Lowry’s figures no better thanformula (Z), even although it contains nine adjustable constants asagainst five, but i t possesses four advantages : (a) it has a moresatisfactory theoretical basis; ( 6 ) it agrees with the figures ofDuclaux and Jeantet to 1 part in 2000 parts (the accuracy claimedfor the experimental figures) even at h = 0.1850 p, whereas equation(2) shows divergences of 1 part in 200 parts; ( c ) it accounts for thepractically constant effect of the infra-red absorption band ; and( d ) it does not introduce a new band in the extreme ultra-violetbut only splits the old ultra-violet band into a close doublet.The refractive and rotatory dispersions of monoethyl 18 andmonoisoamyl l9 aspartates have been examined.In both casesthe rotatory dispersion is anomalous and shows two inflexionssimilar to those in a refractive dispersion curve when passing throughan absorption maximum, but the relation between the refractiveand the rotatory dispersions of these esters is not apparent untilthe curve of dnldh (where n denotes the refractive index) plottedagainst A is compared with the rotatory dispersion curve. Thisbehaviour is not exhibited by the dialkyl esters 2o of asparticacid, which show normal rotatory dispersion. The anomalousbehaviour of the monoalkyl esters is accounted for by internal saltformation.The rotatory dispersion of tartaric acid as measured by T. M.Lowry and P. C. Austin21 has been expressed by F.Biirki22 bymeans of the equation [R] = A/h2~a/*z - B/h2cb/Aa, where A , B, a, andb are constants. The validity of the conclusions of Lowry andAustin-that the addition of sufficient boric acid to aqueous solutionsof tartaric acid ‘‘ fixes ” one of its hypothetical dynamic isomeridesand thus, by eliminating one component of an alleged mixture oftwo substances of opposite rotation and unequal simple rotatorydispersion, produces simple rotatory dispersion in the solution-is rendered doubtful by the work of R. De~camps,~~ who has carriedthe dispersion measurements on these solutions to A = 0.2537 p.He finds that these solutions, although exhibiting apparently simplerotatory dispersion in the visible region of the spectrum, manifesttheir real complexity when observations of rotatory power are pushedinto the region of shorter wave-length.Similar measurements onM. L. Pagliarulo, Atti R. dccad. Lincei, 1927, [vi], 5, 505; A., 1927,610.Is Idem, ibid., 6, 157; A., 1928, 220.2o F. P. Mama and G. Dello Jojo, ibid., 5, 294; A., 1927,500; F. P. Mama,21 Phil. Trans., 1922, [ A ] , 222, 249; A , , 1922, ii, 418.22 Helv. Chirn. Acta, 1928, 11, 369; A., 460.23 Compt. rend., 1927, 3.84, 453, 876; A,, 1927, 307, 409.ibid., 1928, 7, 148; A., 460GENERAL AND PHYSICAL CHEMISTRY. 19solutions of molybdomalic complexes 24 show that these, too, exhibitcomplex rotatory dispersion. A considerable amount of work hasbeen published on the rotatory dispersion of tartaric acid and thetartrates, both alone 25 and in the presence of other salts,26 and thegeneral conclusion seems to be that tartaric acid does exist in twoforms in solution, possibly as simple and complex ions, or in someisomeric forms such as those postulated by Lowry and by Long-chambon.Similar views for alkyl tartrates have been recentlyadvanced by R. Lucas.2'R. de Mallemann 28 has elaborated a theory of rotatory dispersionby considering the mutual action of the atoms of the anisotropicmolecules concerned. When the symmetrical elements in themolecule are arranged so that two of their principal planes areparallel, the rotation should be proportional to the square of thebirefringence. He considers that in every asymmetric medium thereare three directions of propagation of electromagnetic disturbancesmutually a t right angles, so that the properties of the medium maybe completely specified by two symmetrical tensors, the electro-elastic tensor which determines the refractive index, and the rotatorytensor which determines the optical activity.W.Pfleiderer 29 has measured the absorption spectra, the refrac-tive dispersion, and the optical and magnetic rotatory dispersionsof some coloured derivatives of camphor and finds that all thedispersions are anomalous. He has also shown that the magneticrotatory power of toluene in the visible region of the spectrum isproportional to Adnldh. The magnetic rotatory dispersions ofwater and ethyl alcohol 30 and of methyl and n-propyl alcohols 31have been measured for a considerable distance into the ultra-violet region of the spectrum, and in all cases the results can beexpressed by equations of the form = K[h2/(12 - wheren is the refractive index a t wave-length A, 6 is Verdet's constant, lois the wave-length of the absorption band controlling the dispersion,and K is a constant.The values of A, for water and for methyl,ethyl, and n-propyl alcohols are found to be 0.1192, 0.1100, 0*1114,and 0.1138 p, respectively, and it is satisfactory to observe that these2' E. Darmois and R. Descamps, Compt. rend., 1927, 185, 705; A., 1927,26 R. Descamps, Compt. rend., 1927,184,1546; 185,116; A., 1927,723,823.26 E. Darmois, ibid., 184, 1239, 1438; A., 1927, 610, 723; Ann. Phy8ique27 Compt. rend., 1928, 186, 857 ; A., 461 ; see a1,lso P.C. Austin, J., 1928,'* Compt. rend., 1927, 184, 1241, 1374; A., 1927, 610.1126; see also T. S. Patterson and C. Buchanan, J., 1928, 3006.1928, [XI, 10, 70; A., 1320.1825, 1831.2D 2. Physik, 1926, 39, 663; A., 1927, 8.30 D. J. Stephens and E. J. Evans, Phil. Mag., 1927, [vii], 3, 546.31 D. 0. Jones and E. J. Evans, ibid., 1928, [vii], 5, 693; A., 46120 ANNUAL REPORTS ON THE PROGRESS O F CHEMISTEY.are the octave harmonics of weak bands actually observed (in thecase of the alcohols) at 0.2207, 0.2231, and 0.2273 p, respectively.It is considered that the vibrations of lower frequency correspondingto these latter bands do not contribute materially to the magneticrotatory power. It is somewhat remarkable that the magneticrotatory powers of mixtures of water and ethyl alcohol cannot becalculated from a linear-mixture law, since the curve obtainedwhen the compositions of such mixtures are plotted against theirVerdet’s constants is markedly sigmoid in character.G . Calcagni 32has investigated the action of a magnetic field on optically activeas well as on optically inactive substances. He finds that for allsubstances, whatever their concentration, a S-pole at the observerend of the tube gives rise to Z-rotation.S. Mitchell 32a has added one more to the very small number ofsubstances which have been shown to exhibit the Cotton effect(a maximum of rotatory power on one side of an absorption bandand a minimum on the other). Caryophyllene nitrosite forms ablue solution in alcohol, and its rotatory dispersion curve in thissolvent has a positive maximum a t h = 0.6250 p, passes throughzero a t A = 0.6800 p, and is thereafter negative.Its absorptionspectrum shows a narrow band with its head at h = 0.6800 p.Further value is added to these observations by the fact that theabsorption spectra for this solution for right- and left-handedcircularly polarised light were examined, and it was found, inaccordance with expectation, that the extinction coefficients forleft-handed circularly polarised light were greater than the corre-sponding values for right-handed circularly polarised light.The Law of Mass Action.R. D. Kleeman 33 has questioned the accuracy of the law of massaction in the form log K = CV logp deduced by van ’t Hoff forreactions between perfect gases.He draws a distinction betweenmolecules which dissociate when isolated from a reaction systemand those which do not. He terms the former class “sepro-unstable ” and the latter class ‘‘ sepro-~table,~~ and considers thatgaseous reactions in general involve both kinds of molecule. For.instance, in the reaction 2C0, 2CO + 0,, since there is apossibility of the further reaction 0, 20, CO, and 0, are termedsepro-unstable, and CO and 0 sepro-stable. Sepro-stable moleculesobey the gas laws, but sepro-unstable ones do not unless by dis-32 Notiz. chim.-ind., 1927, 2, 429; Chern. Zentr., 1927, ii, 2263; A., 1928,32a J., 1928, 3268.a8 Phil. Mag., 1928, [vii], 5, 268; A,, 239.461GENERAL AND PHYSICAL CWEMISTRY.21sociation they give rise to the same number of resultant molecules asreactant molecules which disappear. In fact, whilst the equationof state for one mole of a sepro-stable ideal gas is v = RT/p, thatfor one mole of a sepro-unstable ideal gas is w = RT/p + E(A,/pn),where Anis a function of the absolute temperature and EA, is zerofor a sepro-unstable gas which does not undergo change of volumeon dissociation. By considering a gas reaction aA + bBcc! + dD, where A and €3 are sepro-stable and C and D are sepro-unstable, employing the classical method of van 't Hoff ' S equilibriumbox, and applying the perfect-gas law to A and B, but the abovemodification of it to C' and D, he arrives at the result that theequilibrium constant, K , is dependent on a factor eKIB2', where X is afunction of the partial pressures of the reacting gases and hence of thevolumes, temperature, and masses of the components of the mixture.Only when X = 0 is van 't Hoff's classical derivation, which ignoresthe possibility of sepro-instability, valid.In some cases X is smallfor relatively large degrees of sepro-instability, in which case, ofcourse, the law as here derived is very little different from theclassical form. The classical law is also a close approximation tothis newer form when the degree of sepro-instability is either verysmall or very great. The possibility of the dependence of theequilibrium constant on the volumes and masses of the reactinggases may also be deduced from kinetic considerations.In a gasreaction? e.g., 2C0, =+= 2CO + 02, the chance of dissociationdepends on the probability of collision of two molecules of CO,, i.e.,on k,[C0,]2, where k, is the velocity coefficient, but since onlyactivated CO, molecules will react, an activation factor, K ~ , mustbe introduced, the value of which must depend on the number andkind of previous collisions which the molecule has suffered. Wethen haveSimilarly, for the reverse action,Hence K = K l k l / K 2 & . Since k, and k, express chances of encounterper unit concentration and are therefore dependent only on theabsolute temperature, but K, and K 2 depend upon the frequenciesof the encounters and upon their nature, and are therefore functionsof the temperature, volumes, and masses of the reactants, we seethat unless K , = K,? K will also be a function of these variables.In a subsequent paper 34 this author considers a reaction M,a +M p various molecules, and derives a differential equationnumber of molecules dissociating per second = ~ ~ k , [ C 0 , ] 2 .number of molecules recombining per second = K2k2[ C0l2[ O,].v(apl?v)T, Ha, ,we - H a v a ( a P a / W T , iwa, M,, - Mev@p&)~, M ~ , M# = 034 Phil.Mag., 1928, [vii], 5, 620; A., 58922 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.by classical thermodynamic methods, and also a similar one when themass of one of the reactants is the independent variable instead ofthe volume. The former equation is applied to various cases ofgaseous reacting systems to evaluate the functional dependence ofK upon v, 27, and M .Special cases for which K is a function of Tonly are discussed. I n this paper fihe ideal-gas law is employedin the form pv = MBT, but in two later papers 35 the same authorarrives at the conclusion that the thermodynamically correctequation is pv = @fRT, where 5 is a function of T which becomeszero when T = 0. It is also a function of v but does not differappreciably from unity unless v is very large. This result has avery far-reaching effect on the kinetic theory of gases, and it isdeduced, amongst other results, that gaseous substances which donot interact chemically nevertheless affect each other’s internalenergies by contact, so that the nature of matter must be continuallychanging, and an atom must therefore bear the impression of allits previous history.It also follows that the equilibrium constantof the law of mass action is almost always a function of the volumesand masses of the reactants from this cause also, but that this effectis appreciable only when the volume is very large. In continuationof these investigation^,^^ the nature of the dependence of on thevolume of the system is derived and it is concluded that E decreasesas v increases. Several applications of this theory are studied and amethod of experimental investigation is suggested, but it is pointedout and emphasised that the magnitudes of these effects are verysmall indeed, and that they may even elude measurement at present.“ But temporary changes may be induced in the atoms of a substancewhich give rise to a temporary and pronounced departure in thechemical behaviour as shown by the phenomenon of datalyticaction.’ ’These somewhat startling results have not escaped criticism, andR. P. Goldstein 37 has raised objections to Kleeman’s derivationof the law of mass action for sepro-unstable molecules, but gives toofew details to enable the value of his objections to be assessed. Healso asserts that Kleeman’s factor K in his kinetic derivation ismerely the activity coefficient of the concentration term. I n hisreply,S8 Kleeman derives his original expression in another wayand disposes of the second criticism by taking a concrete example.Another reply to Goldstein’s second point, although it has not beenmentioned by Kleeman, would appear to be that, since the deriv-ation is applied to perfect gases, the activity coefficients are bydefinition equal to unity, and hence cannot be identified with K.35 Phil.Mug., 1928, [vii], 5, 668, 1191; A., 470, 055.8 8 Ibid., 1929, [vii], 7, 63. 8’ Ibid., p. 206. 38 Ibid., p. 206GENERAL AND PHYSICAL CHEMISTRY. 23Cohesion of Xolids.The problem of the laws of interatomic and intermolecular forcewas rather neglected in the early part of this century, but present-day demands on engineering materials are rapidly emphasisingits importance. In a general survey of the problem of cohesion,C. H. Desch 39 summarises the phenomena of interest to the engineerand metallurgist, depending on the nature of cohesion, under tenheads : (1) the tenacity of solids as measured by ordinary tensiletests is very much less than that demanded by theory; (2) theelastic limit is not a physical constant-permanent deformation,especially in single crystals, appears to set in a t the lowest stresseswhich can be applied; (3) failure under alternating load is byfatigue a t lower stresses than those which cause failure under staticload; (4) cold working has a remarkable effect on the properties ofmaterials; ( 5 ) strain depends on the rate of application of stress;(6) the inter-crystalline boundaries have important effects on theproperties of solids ; (7) the nature of crystalline surfaces is of im-portance in the study of lubrication and welding problems; (8) theproblem of adhesives and solders and the coherence of electrolyticdeposits ; (9) the diffusion of solids ; and (10) the nature of cohesionand its relation to the intrinsic-pressure term in the gas equation ofvan der Waals.A.F. Joffh 40 has investigated the first of these points by meansof some ingenious experiments on rock-salt. By simple tensiletest, this crystal fails at about 0.4 kg./mm.2, whereas theory predictsa tensile strength of 200 kg. /mm.2 ; by ordinary electrical methods,too, rock-salt fails at about 300,000 volts/cm., whereas theoryrequires a dielectric strength of about 100,000,000 volts/cm., adiscrepancy of almost exactly the same ratio. I n the mechanicaltests, the results are vitiated by the presence of minute cracks onthe surface of the crystal which cause intense localisations of stress,and by rapidly removing these cracks (which take time to develop)by solution, breaking loads much nearer to the theoretical areobtained.In this manner, breaking stresses up to 160 kg./mm.2were observed. The fact that no increase in breaking load wasobserved when the crystal was immersed in saturated salt solution,which obviously cannot dissolve its surface, is an indication that theabove explanation of the effect is the correct one and that theincrease in strength was not caused by plastic deformation of thecrystal by testing in water. Nevertheless, the possible objectionthat plastic deformation was responsible for the observed increasein strength was removed by carrying out the experiment in another3s Trans.Faraday Soc., 1928, 24, 53; A., 111.'O Ibid., p. 66 ; A,, 111 ; Phy&al. Z., 1927,28, 911 ; A., 11224 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.manner. A sphere of the material was subjected to stresses pro-duced by unequal thermal expansion. It was first cooled in liquidair and then plunged into molten lead. By this means it wassubjected to a stress of 70 kg./mm.2 and it did not fail under thissevere treatment. The discrepancy between the observed. andtheoretical electrical strengths is due mainly to (a) the productionof Joule heat in the material, (b) ionisation by collision, (c) irregulardistribution of the field, and (d) mechanical stress set up by thefield. It has been completely removed in the case of other dielectrics(glass and mica) by using films 0.2 p in thickness.Further reductionin thickness to 0.014 p did not cause any increase in dielectricstrength. These results open up interesting possibilities inconnexion with the preparation of insulators, condensers, etc.The plasticity of metals and the behaviour of single crystals havebeen studied by M. P616nyi 41 and G. S a ~ h s , ~ ~ and it is shown thatslip planes and lines are always lattice planes and lines in mono-crystalline bodies, and that, in general, the most important planesand lines are those which are most closely packed with atoms.Experiments on fatigue and elastic hysteresis in metals are describedby H. J. Gough 43 and B. P. Haigh,44 and the latter author showsthat the hysteresis-time curves obtained when annealed ductilemetal rods are subjected to approximately sine-wave tensile stressesat a frequency of 2000 cycles per second are characterised by threewell-defined sections : (a) a brief evolution of heat over not morethan 2.5 x 105 cycles, during which period the hysteresis falls to aminimum value, ( b ) a nearly constant, but slowly rising value of thehysteresis, and (c) a rapid increase of hysteresis, immediatelyfollowed by fracture.The properties of non-metallic elements inrelation to their cohesive forces have been studied by A. M. Taylor,45who points out that cohesion may be explained in terms of attractiveforces between electric doublets or between unlike charges. Innon-metals, the bonds are homopolar and the cohesion originates inthe forces between electric doublets, whilst in polar salts (withheteropolar linkages), the force between the ionic charges is super-imposed on this.The electric doublets are produced by the deform-ation of the electron shells surrounding each nucleus, and have amoment p = aE, where E is the intensity of the electric field pro-ducing the deformation. The constant a may be obtained fromthe atomic refractivity or from the correction to the Rydbergconstant in the formula for the series spectra of the element. Thecohesive force is then given byFc = =w9 + x q r ) - CFR(T),41 Tram. Paraday Soc., 1928, 24, 72; A., 9. 42 Ibid., p. 84; A., 111.Ibid.,p. 137; A., 111. 44 Ibid.,p.125; A,, 111. 45 lbid.,p. 167; A., 111GENERAL AND PHYSICAL CHEMISTRY. 25in which the first term represents the effect of the ionic charges,the second that of the electric doublets, the third the repulsion ofthe electron shells, and r is the lattice dimension. I n polar lattices,the cohesive forces vary inversely as the square of the distance,provided that no deformation of the electron shells occurs. Sincethis latter effect gives rise to electric doublets, the force betweenwhich varies inversely as the fourth power of the distance, increasein a is accompanied by an increase in the compressibility, and thiseffect is shown by potassium chloride, bromide, and iodide. Fornon-metallic elements both a and the compressibility are high,and the force between two doublets may be written F = Cp2/+ -p/rn, where C, p, and n are constants. By elimination of p, thisleads to F' = - Cp2(4 - n)/r5, whilst for salts the correspondingexpression is F' = - (er)2(2 - n)/r5.Since p is small comparedwith er, and (4 - n) for non-metals is smaller than (2 - n) for salts,the high compressibility of non-metallic elements compared withsalts is in accordance with theory. F' varies more rapidly with rin non-metallic elements than in polar salts, i.e., the restoring forceacting on a displaced particle is more markedly anharmonic in non-metals than in salts. This points to a higher coefficient of thermalexpansion in the former case, which is in agreement with observation.The cohesion of soldered joints has been studied by T.B. CTOW,*~who finds that, with electrolytic copper rods joined by eutecticsolder, contact alloys were formed at the joins and that fractureoccurs through these.T. W. Richards,47 after reviewing the progress of research (largelyhis own) on the relation between the volumes and compressibilities ofsolids and the comparison of the energy changes with the changesof volume which occur during a chemical reaction, arrived at theconclusion that both cohesion and chemical affinity exert pressurewhich tends to diminish the volume of the system concerned. Themain influences at work in any physico-chemical atomic contactsmay be represented by an expression equating compressing anddistending agencies in equilibrium, thus, p + x = x,, + Pe, inwhich p represents the external pressure, x the sum of all the intrinsiccompressing effects, x p the intrinsic repulsive effects, and Po thethermal pressure, which may be approximately evaluated as Ta/p,where a and p are the coefficients of thermal expansion and com-pressibility, respectively.Since both x and x,, are observed todiminish with increase of volume, this equation may be writtenwhere the subscript indicates properties measured in some standardstate, and m and n are unknown and are not necessarily constant.P + X0(210/@ = *%(vo/u>n + TalP46 Tram. Paraday Xoc., 1928,24, 159. 4 7 Ibid., p. 111; A., 11226 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.However, n must certainly be greater than m, otherwise a slightincrease of external pressure would cause the substance to collapse.This equation leads to an expression for the internal pressure,xo = 1/P(n - m).The values of no for different elements computedby means of this equation are large, but appear quite reasonable.For binary compounds the equationis suggested, in which x is the fraction of each atom subjected onlyto cohesive pressure, xl, and (1 - x) is the fraction subjected tointense chemical pressure, x2. It is estimated that whilst, forexample, the pressure between the molecules of liquid bromine is ofthe order of 5000 atmospheres, that between the bromine atoms inthe molecule is of the order of 100,000 atmospheres. From thenumerical values of this kind thus deduced, it appears that thewidely held view, that the latent heats of vaporisation and ofchemical reaction represent simply the net amount of work doneby affinity when molecules (in the former case) or atoms (in thelatter) approach one another from a considerable distance, iscorrect.The value of the index in a power law of molecular force is dis-cussed by A.W. Porter,48 but it is concluded that no trustworthydeduction can yet be made. Glass is considered as a fourth stateof matter 49 since there is a marked discontinuity in the physicalproperties, e.g., the heat capacity, when a liquid passes into theglassy form. Moreover, the glassy and crystalline states havenearly the same heat capacity. A glass, like a liquid, possesses arandom arrangement of its units but, like a solid, is held togetherby fixed, rigid linkings.It is considered improbable that the glassylayer formed by polishing a solid surface is the result of actualliquefaction, since, once a group of molecules is torn from its positionin the lattice, it is practically impossible, under ordinary polishingconditions, to force it back within the range of molecular cohesion,5*and, moreover, the solidification of a fused layer might result inrecry~tallisation.~~ The compressibility of metallic alloys has beenstudied by R. F. Mehl and B. J. Mair,52 who find that it is alwaysless than that indicated by the simple-mixture law, the deviationincreasing as the dissimilarity of the metals increases. The differ-48 Trans. Forachy SOC., 1928, 24, 108.49 G. S. Parks and H.M. Huffman, Science, 1926, 64, 363; A,, 1927, 300.50 J. W. French, Nature, 1927, 119, 527; A,, 1927, 510.5 1 N. K. Adam, ibid., p. 162; A., 1927, 192.52 J . Amer. Chem. Soc., 1928, 50, 55; A., 229; see also R. F. Mehl, Amer.Inet. Min. Met. Eng., Tech. Pub., 1928, No. 67; A., 699GENERAL AND PHYSICAL CHEMISTRY. 27ence is attributed to the chemical affinity of the metals. A classi-fication of metallic substances into the following groups has beensuggested 53 : (a) metallic elements, which may be isotopicallysimple or complex ; (b) primary metallic solid solutions which retainthe crystal structure of the parent metal and form the end phasesof ordinary equilibrium diagrams ; (c) secondary solid solutionswith a crystal structure different from that of the parent metal, butwith no indication of the formation of compounds; and (d) inter-metallic compounds.W. Hume-Rothery has also critically reviewedexisting theories of the metallic state.54 Drude’s electron gastheory, the electrical doublet theory of Thornson, the theory ofWien and Gruneisen, Lindemann’s electron lattice theory, andBridgman’s theory all account more or less for the electrical andthermal properties of metals, but Lindemann’s theory is the onlyone which is in general agreement with compressibility data andtensile properties. It is also the only one which gives an explanationof the plasticity of metals, which is considered to be due to therelatively great size of the positive ions compared with the electronswhich form the other components of the lattice.The supra-conductivity shown by some metals at the temperature of liquidhelium is considered to be due to the precessional motion of theelliptic electronic orbits causing the zones of repulsion round themetallic ions to vary periodically. This conception agrees withthe fact that supra-conductivity is shown by some metals and notby others. New statistical methods have been applied to theproblem of the distribution of electrons in a metal by J. E. Lennard-Jones and H. J. Woods,55 by A. Sommerfeld 56 to account forelectrical and thermal effects, and by other workers in studies ofelectron emission from cold metals 57 and of the Volta effe~t.5~Oxide Films on Metals.The study of metallic corrosion has greatly extended our know-ledge of the properties and the conditions of formation of oxidefilms upon the surface of metals.It will be convenient to discussthis subject under two headings : (a) films formed by atmosphericaction, and (b) films formed by electrolytic action.(a) Films formed by Atmospheric Action.-The production ofb3 W. Hume-Rothery, Phil. May., 1928, [vii], 5, 173; A., 222.64 Idem, ibid., 1927, [vii], 4, 1017; A,, 111.5 5 Proc. Roy. SOC., 1928, [ A ] , 120, 727; A., 1299.5 6 2. Physik, 1928, 47, 1, 43; A., 467; see also Naturwiss., 1927, 15, 825;6’ W. V. Houston, 2. Physik, 1928, 47, 33; A., 467.68 C. Eckart, ibid., p. 38; A., 467.1928, 16, 374; A., 68128 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.colours (temper colours) on steel and other metals has generallybeen assumed to be due to the formation of transparent oxide filmswhich are sufficiently thin to give rise to interference effects.59This has been confirmed experimentally by U.R. Evans,6o who hasshown that the bands of colour produced by heating one end ofa strip of iron can be caused to move along the strip without changingtheir order if the thickness of the graduated film of oxide is uniformlydiminished by careful cathodic reduction in dilute acid. A similareffect has been obtained by C. W. Mason by simple solution inacid, and by R. C. Gale 62 by polishing. Confirmatory evidence ofthe real existence of an oxide film on passive iron mirrors depositedon glass by thermal decomposition of the pentacarbonyl has beenobtained 63 by following the changes in the condition of polarisationof the light reflected from the mirrors before and after exposureto the air. F.H. Constable 64 has shown that oxidation colourson copper may be made homogeneous if precautions are taken inpreparing the film to ensure uniform oxidation a t all parts of thesurface. His results agree with the interference theory, and theabsolute thickness of the oxide film calculated from the density ofthe oxide and the mass of oxygen absorbed per unit area of surfaceagrees moderately well with the thickness calculated from theposition of the absorption band and the corresponding refractiveindex. The connexion between tarnishing and reflecting power hasalso been studied by G.And0.65 By means of X-ray powderphotographs, R. M. Bozorth e6 has found that the protective coatingdue to the action of steam on iron a t 700°, followed by cooling inair, consists of layers of FeO, Fe,O,, and Fe20, in the order ofoxidation, the respective thicknesses being estimated as 100, 2, and0.2 p. The rate of formation of oxide films on metals has beenstudied very thoroughly by using optical, electrical conductivity,and gravimetric methods. N. B. Pilling and R. E. Bedworth 67find that at high temperatures copper, nickel, zinc, and iron obeya parabolic law, W2 = kt, for the increase of weight with time.Cadmium and aluminium show a similar behaviour at first, but the69 G. Tammann, 2. anorg. Ch.e?n., 1920, 111, 78; 1922, 124, 25; G.Tam-mann and W. Koster, ibid., 1922, 123, 196; A . , 1922, ii, 831.6o Proc. Roy. Soc., 1925, [ A ] , 107, 228; A , , 1925, ii, 288.61 J . Physical Chem., 1924, 28, 1233; A., 1925, ii, 108.62 J. SOC. Chem. Ind., 1921, 43, 3 4 9 ~ ; A., 1925, ii, 109.153 H. Freundlich, G. Patscheke, and H. Zocher, 2. phyailal. Chent,., 1927,128, 321; 130, 289; A., 1927, 1037, 1149.64 Proc. Roy. SOC., 1927, [ A ] , 115, 570; A., 1927, 930.15j Mem. COX Sci. Kyoto, 1928, [-4], 11, 85; A, 717.6 G J . Arner. Chem. Soc., 1927, 49, 969; A,, 1927, 602.c 7 J . Inst. Metala, 1923, 29, 629UENERAL ABND PHYSICAL CHEMISTRY. 29rate of increase of weight diminishes rapidly later. J. S. Dunn 68finds a similar law for 95/5 and 90/10 brass, but suggests WZ = E,dfor 71/29 brass, where n is slightly greater than 2.I n a laterpaper,69 he finds that between 209" and 284" copper obeys theparabolic law, but that about 200" deviations occur which heattributes to the existence of a transition point for the oxide nearthis temperature.W. H. J. Vernon 7O finds that heating copper for a short time inair a t 75" confers immunity from tarnishing, presumably by theformation of an invisible oxide film. The fact that similar heatingat 65" does not have this effect suggests that there is a minimumthickness of the film required for protection, and calculation indicatest h a t this minimum film is the unit lattice of cuprous oxide. I n the'' Second Experimental Report to the Atmospheric CorrosionResearch Committee (British Non-Ferrous Metals Research Associa-tion)," $1 this author distinguishes three kinds of weight increment-time ciirve a t ordinary temperatures :(i) The parabolic relationship already referred to, where the processof tarnishing is regulated by the diffusion of the atmosphere througha continuous solid film which itself thickens as a result of thisprocess. This is true for copper except a t the very beginning ofthe process when the film is not completely formed (on a plate ofmetal the film forms from the edges, inwards).In this case, it issomewhat remarkable to note that the rate of attack is determinedby the conditions prevailing at the time of the initial exposure,and that the external conditions may subsequently vary withinextremely wide limits without disturbing the course of the attack.He also finds that oxide films on copper are relatively imperviousto oxygen at ordinary temperatures, and very impervious tohydrogen sulphide, but that sulphide films are relatively perviousto both oxygen and hydrogen sulphide.This is the case with a perviousfilm like that on zinc, where the velocity pf oxygen addition dependsonly on the rate of diffusion of the atmosphere to the surface to beattacked.(iii) A curve beginning as a parabola and rapidly flattening towardsthe time axis.This kind of curve is obtained with aluminium andlead. It is characteristic of the adsorption isotherm, and it issuggested that this phenomenon plays a part in the mechanismof formation of the film. The curves obtained for brass in theirearlier stages resemble the copper curves, but in their later stagesresemble those for zinc.(ii) A linear relation, W = E't.6 8 Proc.Roy. SOC., 1926, [ A ] , 111, 203.'1 Traw, Faraduy SOC., 1927, 23, 113; B., 1927, 626.6@ Ibid., p. 210. ' 0 J . , 1926, 227330 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The variation of the velocity of film formation with temperaturehas also been studied in the case of copper,68s 7Os 72 and has beenfound to follow the van 't Hoff isochore. The slope of the straightline obtained when the logarithm of the velocity coefficient isplotted against the reciprocal of the a.bsolute temperature is less forfilm formation than in the case of the similar curve for the dis-sociation of cupric oxide, thus indicating that the intermediateformation of this oxide is not a possible mechanism.An empiricalequation, K = aT*, has also been proposed for the variation of K ,the oxidation velocity coefficient, with temperature for copper 67 andfor 60/40 brass. 70(b) Films fwmed by Electrolytic Action.-Temper colours havebeen produced by anodic attack on iron in aqueous caustic sodaby superimposing alternating on the direct and also bythe action of chromate solutions containing chloride. 73 The oxide-film theory of passivity, however, has not hitherto secured fullacceptance, chiefly for two reasons : (i) no film is usually visible on apassive metal, and (ii) metals covered with a visible film are oftennot passive. The second objection may be met by pointing outthat a film which is thick enough to be seen is likely to crack becauseof the difference between the specific volumes of the oxide and thatof the metal conta.ined in i t .6 7 The first objection has now beenremoved by U. R'. E ~ a n s , ~ 4 who has isolated the film of oxide whichcauses passivity of iron. Pure electrolytic iron was renderedpassive by treatment with chromate, nitrite, or caustic soda, andthe film was ruptured along a line, either by trimming the metal orby scratching. The iron was then removed by anodic treatment insodium chloride solution or by dissolving it in a saturated solutionof iodine in potassium iodide. In this manner the film was obtainedas thin transparent flakes preserving the original form of the surfaceof the specimen.This film is permeable to chloride ions, which maytherefore cause the underlying iron to be attacked if conditions aresuch as to allow of the production of local electric currents. Similarfilms were isolated from passive copper and aluminium, but thepassivity of copper is less persistent than that of iron, although thepassivity of aluminium is more so. No film could be isolated fromiron passivated in nitric acid, but E. S. Hedges 75 has obtainedconvincing indirect evidence of its existence and nature. He hasshown that the lowest concentration of nitric acid required topassivate electrolytic iron at 30" is SS%, and that this result isreproduced with ease, provided that great care is taken t o ensurethat the specimen is passed rapidly through the surface of the acid,78 A.J. Allmand and R. H. Barklie, Trans. Far&y SOC., 1926, 22, 34; B.,1926, 277, 497.74 J . , 1927, 1020.73 U. R. Evans, J . SOC. Chem. I n d . , 1926, 44, 163.1..7 b Ibid., 1928, p. 969GBN'JERAL AHD PHYSIUAL CHElllISTRY. 31which has an activating effeot. By whirling passive iron a t 3000r.p.m. in concentrated nitric acid, it becomes active after a shortperiod of induction which corresponds to the time taken to dissolvethe film of oxide. This result is counter to the theory of A. S m i t ~ , ~ ~which predicts that the more rapid removal of ions from the surfaceof the metal by whirling should produce a greater disturbance of theinner equilibrium at the surface, and should thus produce a greaterpassivity.The reality of the presence of the oxide film on thesurface of pwsive iron is shown by the fact that this metal beginsto dissolve in nitric acid a t 746-7545" whatever the concentrationof the mid, and that freshly ignited ferric oxide is not appreciablydissolved by concehtrated nitric acid until this temperature isreached. Other metals (cobalt, nickel, and copper) are renderedpassive by concentrated nitric acid at - 11". The fact that passivityis shown by met& outside the iron group indicates that explanationsbased on the theory that passivity is due to the assumption by themetal atoms of an electron structure of the inert-gas type (e.g., foriron, 2, 8, 8, 8 inatead of 2, 8, 14, 2), as suggested by A. S. Russell,''S.Glmstone,78 and W. D. Lansing79 are not likely to be correct.Hedges has also shown that anodic films-not necessarily of oxide-are formed, in some cmes in a periodic manner, by copper and silver,8ozinc, cadmium, mercury, tin, and lead,81 and iron, cobalt, nickel,and aluminium,82 and that these films follow the regions of highcurrent density at the edges and corners of a rectangular electrode.83G. G r u b @ has reviewed and discussed some theories of passivity,and concludes that anodic passivity is caused in iron, cobalt, andmanganese by the deposition of films of oxide of the type M,O,.Electrd Potentials.The use of oxidation-reduction potentials in biological work israpidly extendmg, and an adequate introduction to the theory andpractice of the various methods employed is to be found inW.M. Clark's " The Determipation of Hydrogen Ions," which hasnow attained a third edition.85 The treatment of the subject bymeans of a space model with pH, percentage oxidation, and potentialM co-ordinates brings out well the dependence of oxidising orreducing intensity on pE, and the method is capable of wider applic-ation. The use of the symbol rH to denote the decadic logarithmof the reciprocal of the equivalent hydrogen pressure of an oxidation-78 " Theory of Allotropy," Longmans, 1922, p. 345. '' Nature, 1926, llS, 456; 1926,117, 47; A., 1925, ii, 406; A,, 1926, 133.7n PhyeiOaa Rev., 1927, [ii], 29, 216; A., 1928, 1303.a4 2. Elektrochem., 1927, 88, 389; A., 1927, 1034.86 BeilliBre, Tindall end Cox, 1Q28.J., 1926, 2887.Ibid., p.2682.J., 1926, 1533.88 Ibid., p. 2878. 8a &d., 1927, 271032 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.reduction system is now discouraged by its originator 86-it hasevidently proved a dangerous tool in unskilled hands. The numberof oxidation-reduction indicators continues to increase. A colori-metric method of determining oxidation-reduction potentials hasbeen worked out for methylene-blue by P. Hirsch and R. Ruter.87This is somewhat similar to the well-known method for p,, butsince another variable, the acidity of the solution, affects the results,it is necessarily somewhat more complicated. M. Phillips, W. M.Clark, and B. Cohen 88 have made potentiometric and spectro-photometric studies of Bindschedler’s green and toluylene-blue forthis purpose, and have compared the behaviour of the indaminedyes with that of the thiazines-the basic indamine dyes form usefulalternative oxidation-reduction indicators to the acidic indophenols.E.Aubel, L. Genevois, and R. Wurmser 89 have determined theoxidation-reduction potentials of a number of dyes, and G. Blixhas investigated the decolorisation time of methylene- blue inhexose-phosphate mixtures. Oxidation-reduction buffer solutionsare also described 87 for various ranges of pH-for example, cuprous-cupric chlorides in potassium chloride, ferrous-ferric oxalates inoxalate and in citrate buffers. The behaviour of various dyes inaccelerating the attainment of oxidation-reduction potentials insystems containing dextrose has also been ~tudied.~lThe polarographic method of determining oxidation-reductionpotentials of organic compounds at a dropping-mercury cathode bythe automatic tracing of voltage-current curves has been described.92It has been applied to isovaleraldehyde,g3 for which the equationx = - RTJ2P.log k’/([H+I2 x CgaH0) is valid. For a 0.1868M-solution in 0-1N-hydrochloric acid, log E’ = 34.672, and m-theadsorption coefficient for the aldehyde a t the electrode-is 1.380in a strongly acid solution, and depends on the pH of the solution.It is claimed that the polarographic method is twenty times assensitive as Schiff’s reagent for the detection of aldehydes. Whenthis method is applied to the reduction of pyridine solutions,94 theagreement between the observed results and the equation is lesssatisfactory, especially in alkaline solution, but the curves obtainedindicate that reduction of both ions and molecules of pyridineoccurs.The reduction of nicotinic acidg5 by this method occurs2. arial. Chenb., 1926, 69, 193; A,, 1927, 23. Op. cit., p. 387.88 US. Public HeaEth Service, Suppl. 61 ; A., 129.8s Compt. rend., 1927, 184, 407; A., 1927, 316.Skand. Arch. Physiol., 1927, 50, 8 ; Chena. Zentr., 1927, ii, 1352; A.,s1 R. Wurmser and J. Geloso, Compt. rend., 1928, 186, 1842; A., 846.92 M. Shikata, Mem. Coll. Agric. Kyoto, 1927, 4, 1; A., 1928, 136.s3 M. Shikata and I. Trachi, ibid., p. 9; A., 1928, 136.O4 Idem, ibid., p. 19; A., 1928, 136.1928, 260.85 Idem, ibid., p.35; A., 1928, 136GENERAL AND PHYSICAL CHEMISTRY. 33in two stages. The method has also been applied to the Iuicro-detection of lead and c0pper,~6 and of reducing substances infermented liquors.97 It has been shown by the same method thatthe normal reduction potentials of maleic and fumaric acids areidenticaLg8A study of Haber's glass electrode has been made by W. S.Hughes,99 and it is recommended that the glass used should be asfree as possible from potash, alumina, and borates : the bulb shouldbe thin and devitrification should be avoided. The behaviour ofthe cell is best explained on the hypothesis that the hydrogen-ionconcentration in the glass phase is maintained relatively constantby the buffer action of the sodium acid silicate contained in it.Many metals are capable of utilisation as electrodes to give end-points in the potentiometric titration of acids and bases, and success-ful results by using tungsten, molybdenum, arsenic, antimony,bismuth, aluminium, and tin for this purpose have been rec0rded.lThe antimony-antimony trioxide electrode has been very fullyinvestigated, and it is considered that the unsatisfactory resultshitherto obtained with it are due to the dimorphism of the oxide.Antimony trioxide changes from the cubic to the rhombic form a t570" lo", and the form produced by the hydrolysis of the tri-chloride is naturally the metastable one (rhombic). Trustworthyresults with this electrode are obtained only when this metastablephase and dissolved oxygen are eliminated and equilibrium isapproached from the alkaline side.When these precautions aretaken, the potential is a linear function of the pH, and the normalpotential referred to the hydrogen standard is + 0.1445 & 0.002volt. Since the electrode thus prepared is permanent and constantand requires little attention, it is considered to be superior to thehydrogen electrode. A new method of avoiding liquid junctionpotentials, with their attendant uncertainties, in the determinationof electrode potentials, has been de~cribed.~ A fine-meshed earthedmetal gauze is placed above and parallel to the surface of the solution,and is surmounted by a parallel metal plate connected to an electro-meter. The air in the vicinity of the metal gauze is ionised bymeans of a constant radioactive source, and the potential differenceg6 M.Shikata, Mem. Coll. Agric. Ky6t6, p. 49; A., 1928, 136.9 7 M. Shikata and K. Shoji, ibid., p. 75; A., 1928, 136.98 P. Herasymenko and Z. Tyvoliuk, 2. Elektrochem., 1928,34, 7 4 ; A., 482.l J. 0. Kloss and L. Kahlenberg, Trans. Amer. Electrochem. SOC., Sept.E . J. Roberts and F. Fenwick, J . Amer. C'hern. Soc., 1928, 50, 2125; A,,J., 1028, 491.1928; A., 1203.1098.3 M. Andauer, 2. plc.y~il;nl. C l m t b . , 1027, 125, 135; A., 1927, 316.REP.-VOL. XXV. 34 AXNUAL REPORTS ON "HE PBOQRESS OF CHEMISTRY.between the electrode and the solution is determined from thechanges in the leakage current from the charged electrometer whenthe electrode, plus a source of known potential in series with it, isconnected to earth.A number of new methods of potentiometric titration haveappeared.A useful collection of the methods in use up to 1926has been p~blished,~ but readers should beware of the mathematicaltreatment of the titration error on p. 79 which has apparently beencompetently deduced but has subsequently been badly muddledand unintelligently abbreviated. B. Cavanagh 5 has describedan absolute method of potentiometric titration which avoids theuse of liquid junctions. It depends on the fact that the E.M.F.between two different electrodes in the same solution is E = E, +RT/F . log (C, x C,), where C , and C, are the concentrations of therespective ions. The end-point E.M.F. for one ion can thereforebe calculated if the concentration of the other and the appropriateionic or solubility products are known.In effect, the method thusconsists of combining the reference half-cell in the same solutionas that to be titrated. The use of a potentiometer may be avoidedby employing an end-point cell of similar construction connectedin opposition in the usual manner. Theoretically, it should bepossible to adjust the concentration of one ion so that when theother is at the end-point concentration, the total E.M.F. is zero,and thus avoid even the use of a reference end-point cell. Thepossibility of actually realising such conditions, however, dependson the numerical values of the normal electrode potentials concerned.Thus, for example, with a hydrogen and a silver chloride electrode,for the E.M.F. to vanish when the pH = 7 would require a chloride-ion concentration of about 1011N, whereas with a quinhydrone and asilver chloride electrode the corresponding concentration is onlyN/450. Several cases are examined and limits of accuracy arediscussed. The same author has devised a modified method ofpotentiometric titration depending on changes of potential at theindicator electrode, and has given tables from which the end-pointof a titration can be evaluated by a method of successive approxim-ation without actually reaching it. The absolute uncertainty ofthis method is of the order of one-fifth of the solubility of the pre-cipitated salt (or other corresponding constant), but somewhathigher precision may be obtained by modified methods '---forwhich tables and curves are also given-provided that the titration4 I. M. Kolthoff and N. H. Furman, " Potentiometric ~itrstions," Wiley6 J., 1927, 2207.Ibict., p. 855.and Sons, 1926.Ibid., 1928, 843GENERAL AND PHYSICAL CHEMISTRY. 35curve canforms to an equation deduced by thermodynamicmethods :In this equation, M denotes the number of C.C. of reagent still tobe added to complete the titration, n is the normality of thereagent, y’ and y are respectively the activity coefficients of thepositive and negative ions, 0’ and 8 are the fractions of the ionsnot adsorbed by the precipitate, s2 is the activity product of theions concerned, V is the volume of the solution, E is the potentialof the electrode, P, R, and T have their usual thermodynamicsignificance, the suffix e denotes end-point values, and the alternativesigns in the last term are used in conformity with the sign of thecharge on the ion corresponding to the nature of the electrode used.E. Miiller and H. Kogert * have described a modification of thebimetallic electrode method of potentiometric titration, usingelectrodes of the same metal and obtaining the end-point by deter-mining the maximum potential difference instead of the maximumrate of change. They have also described a method9 by which twosimilar electrodes are placed a t some distance apart in the solutiont o be titrated, the reagent is introduced near one, and the solutionis stirred towards the other. The first electrode is therefore incontact with a solution containing excess of the added reagent,and thus acquires a potential different from that of the second,which is in contact with the mixed solution. At the end point, thetemporary deflexion of a galvanometer connected across the twoelectrodes is said to be practically zero.HAROLD HUNTER.8 2. physikal. Cl~ern., 1938, 136, 437; A., 1203.9 Ibid., p. 446

ISSN:0365-6217    

DOI:10.1039/AR9282500011

出版商:RSC    

年代:1928

数据来源: RSC

摘要:

INORGANIC CHEMISTRY.THE steady revival of interest in Inorganic Chemistry which hasbeen apparent for some years has become more marked during theperiod covered by this Report. A considerable increase in thevolume of useful and interesting work has enhanced the dif%cultyof selection and adequate treatment. The Report follows thegeneral lines of those of previous years, and the remarks prefacingthe Report for 1925, to which the reader’s attention may be directed,are applicable in the present case.Subjects which appear to be of special interest are: helides(p. 40); the chemical evidence that c&um and titanium are not‘‘ simple ” elements (pp. 37,38) ; the evidence that the heavier iso-tope of potassium is probably responsible for the radioactivity of thatelement (p.42); reactions of beryllium and its salts in liquidammonia (p. 44); a full investigation of calcium nitrides (p. 45);a new classification of the rare earths (p. 48); the products of thereaction of carbon disulphide with sodium amalgam (p. 50) ;silicic acids and the silicates (p. 51); germanium compounds (p.6 3 ) ; nitrogen trifluoride (p. 54); compounds of sulphur andselenium (pp. 57, 58) ; the chemical properties of rhenium (p. 60).Reference may be made to a type of glass-to-glass joint on theball-and-socket principle which appears to have been in use amongmetallurgists in Germany for some time and to have given excellentresults. The pieces of glass forming the joints are flanged andground to an accurately standardised curvature in the form of ballsand sockets which are thus interchangeable.The joints are madegas-tight by the thinnest possible film of grease applied to theengaging surfaces, which are held together by a special clamp.Advantages of such joints are that they may be made betweendifferent materials with much less risk of fracture than is the casewith ordinary ground joints, that they are flexible to a certaindegree, that they do not seize, and that they are made and brokenwith a minimum of movement of the rest of the apparatus.1Atomic Weights.Neon and Argon.-The normal density of neon, after exhaustivechemical purification followed by fractional adsorption, is found toE. I. Lewis, J . Soc. Chem. I&., 1928, 47, 1238INORGANIC CHEMISTRY. 37be 0.89990, whence the atomic weight is Ne = 20.182.By similarmethods the normal density of argon has been found to be 1078364,whence A = 39.943. By rejecting the conventional assumptionthat the value of PV for one atmosphere is correct, distributing theerrors by finding the best straight line representing the observedvalues of some simple function of the density plotted against thepressure, and then extrapolating to zero pressure, small differenceshave been found between the calculated and observed values of thedensities a t different pressures. The effect on the deduced atomicweight is always less than 0.001 unit, although fortuitously the thirddecimal place is affected in the case of neon and argon. The valuescalculated by this method are : Oxygen 16.000, nitrogen 14.008,neon 20.183, argon 39.944.The value of the limiting density ofoxygen is 1-42764, which yields as the limiting value of the molalvolume 22.4146 litres (g = 980~616).~Ccesium.-On account of the discordance between the dataobtained for this element by chemical methods and by the mass-spectrograph, the ratio CsCl : Ag has been redetermined, the cEsiumbeing purified by recrystallisation of the alums and not, as previously,of the dichloroiodide. Four determinations gave in mean Cs =132.809 -& 0.012, this " probable " error being within the experi-mental error, -& 0.015, estimated from the known errors of weighingand t i t r a t i ~ n . ~ This result confirms the accepted atomic weight,4Cs = 132.81, and thus indicates a " packing fraction " of - 14 xlo4, appreciably greater than that to be inferred from Aston'scurve.5 It is therefore suggested (compare titanium, below) thatcasium may be not a " simple " element, as has been supposed, buta mixture of isotopes.SiEver.-A preliminary account of determinations of the ratiosBa(C10,), : BaC1, : 2Ag indicates that the derived ratio Ag : 4 0gives Ag = 107.880, in agreement with the accepted value.6Erbium-Erbium giving a constant equivalent is obtained fromerbium-yttrium material from gadolinite, by fractionation using thenitrate fusion method or by fractional precipitation with sodiumnitrite.' The mean of six determinations of the ratio ErC13 : 3AgG. P.Baxter and H. W. Starkwesther, Proc. Nat.Acad. Sci., 1928, 14,T. W. Richards and M. Franqon, J . Amer. Chem. Soc., 1928, 50, 2162;* T. W. Richards and E. H. Archibald, Proc. Amer. Acad. Art8 Sci., 1903,ti F. W. Aston, Proc. Roy. SOC., 1927, [ A ] , 115, 487; A,, 1927, 914.6 0. Honigschmid, 2. Elektrochem., 1928,34, 625; A., 1168.60, 57; A., 343.A., 1069.38, 443 ; A., 1903, ii, 366.A. E. Boss (with B. S . Hopkim), J , Amer. Chern. SOC., 1928, 50, 298;A., 34338 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.gave Er = 167.64 (Ag = 107.88), a figure but slightly lower thanthe accepted value 167.68.*Titanium-Titanium tetrabromide has been purified and analysedby the methods previously employedg for the preparation andanalysis of titanium tetrachloride which had given Ti = 47.90.Ten determinations lo of the ratio TiBr, : 4Ag have given Ti =47.900 5 0.0013, the extreme deviation being for the whole series0.019 unit and for six of the results less than 0.007 unit.This valueconfirms the earlier determination and accords with the general rulethat the masses of individual isotopes fall short of the integral valueswhen the mass number is between 20 and 200, but it leads to apacking fraction nearly three times as large as that derived fromAston's c~wve.~ In the first examination of titanium in the mass-spectrograph, Aston 11 found doubtful indications of an isotope ofmass 50, besides the main isotope of mass 48, and it seems possiblethat the discrepancy may be due to an undiscovered lighterisotope.Nitrogen.-The mean density of nitrogen, obtained from fourdifferent sources, has been found to be 1.25049 &- 0*00003 g./litre.The most probable value of the atomic weight is 14.0082 & 0.00042.12Antimony.-The ratio SbBr,: 3AgBr has been found in 25determinations l3 on material from five different sources.Theresults in terms of atomic weight range from 121.744 to 1210754, thevariation being less than the estimated experimental error.Uranium-Uranous chloride has been prepared and analysed bythe methods previously used for the bromide,14 and 19 determin-ations of the ratio UCl, : 4Ag and 18 of UCl, : 4AgC1 have been made.The results for both ratios lead to the value U = .%38.14.15Intensive Drying.The work published in this field during the year presents a conflictIt has been pointed out that the view l6 that the rise in boilingof evidence and is therefore reported here without comment.* K.A. Hofmann, Ber., 1910, 43, 2631; A., 1910, ii, 1073.G. P. Baxter and G. J. Fertig, J . Arner. Chem. SOC., 1923, 45, 1228; A.,1923,ii,498; G. P.BaxterandA. Q. Butler,ibid., 1926,48,3117; A,, 1927,86.lo Idem, ibid., 1928, 50, 408; A., 343.l1 F. W. Aston, Phil. Mag., 1924, [vi], 4'7, 397; A., 1924, ii, 225; comparel2 E. Moles and J. M. Clavera, 2. anorg. Chem., 1927,16'7,49; A,, 1927,1120.l3 K. R. Krishnaswami, J., 1927, 2534; A,, 1927, 1120.l4 0. Honigschmid, 2. Elektrochem., 1914, 20, 452; A., 1914, ii, 662; 0.Honigschmid and (Mlle.) 8. Horovitz, Monai%h., 1916,3'7,185; A., 1916, ii, 484.lS 0. Honigschmid and W.E. Schilz, 2. anorg. Chem., 1928,1'40,145 ; A., 669.Ann. Reports, 1924,21, 238.D. Balarev, J . pr. Chem., 1927, ii, 116, 57; A,, 1927, 613INOWANIO CHEMISTRY. 39points of substances dried over phosphoric oxide may be due to thepresence of phosphoric acid or its esters is untenable, and that thepresence of phosphorus in dried liquids is due to phosphorus trioxidein the pentoxide used.17 Other workers la report that, after about4 years' intensive drying with phosphorus pentoxide at the ordinarytemperature, no abnormal rise was observed in the boiling points ofbenzene and carbon tetrachloride.Nitrogen peroxide and phosphoric oxide when heated togethergive rise to at least three simultaneous reactions : (a) they form anadditive compound ; (b) the peroxide is dissociated into nitric oxideand oxygen to a greater extent than is the moist gas, and theseproducts do not recombine in cooling; (c) the nitric oxide decom-poses into its elements at a greater rate than normally.The lasteffect is ascribed to the catalytic effect of the large surface ofphosphoric oxide, whilst the relative extent to which these reactionsproceed depends on the temperature and duration of the heating.Nitrogen peroxide which has been intensively dried a t the ordinarytemperature, however, does not dissociate very considerably intonitric oxide and oxygen when heated a t 550" for 24 hours, but whenheated a t 620" for some time seems to revert to the normal state,possibly owing t o a superficial decomposition of the glass.In thedried gas the rate of polymerisation of the coloured NO, moleculesto form colourless N20, molecules is retarded.lgIt has been suggested20 that inner transformations in the liquidphase of a single substance have not yet been stopped by theprocess of intensive drying, the evidence of surface tension beingrejected as an untrustworthy criterion for internal equilibria, andother evidence being discarded on the grounds that it was obtainedunder conditions of rapid evaporation or distillation which did notallow the attainment of equilibrium.Group 0.The observations that the heat of vaporisation of liquid heliumshows a maximum near 3" Abs.21 and that the plot of surface tensionagainst temperature shows a change in direction at 2.4" Abs.22 have17 H.B. Baker, J., 1927, 2902; A., 1928, 10; idem, J. pr. Cham., 1928, ii,I* S. Lenher and F. Daniels, Proc. Nat. dcad. Sci., 1928, 14, 606; A,,10 J. W. Smith, J., 1928, 1886; A,, 953.20 A. Smits, J., 1928, 2399; A., 1189.21 L. I. Dana and €3. K. Onnes, Proc. K . Akad. Wetensch. Amsterdam, 1926,28 Ann. R e p W , 1926,23,52.118, 96; A., 354.1189.29, 1051; A., 1927, 10140 AXNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.an added significance by reason of the discovery that the heating andcooling curves, taken at 38 mm. pressure, show a slight halt at 2.3"Abs. These data are held23 to indicate that helium forms twodifferent liquid phases, having a heat of transformation (calculatedfrom the specific heats 24) of -0.13 g.-cal./g., to yield the form stableat higher temperatures, which has the higher density and surfacetension and the lower heat of vaporisation.Similar properties havepreviously been observed only in more complex substances.Mercury oscillating with the production of a glow dischargein contact with certain pure common gases at pressures of afew mm. has been shown to yield solid compounds, whilst asingle experiment with helium resulted in a lessened gas pressurefrom which the synthesis of a helide was inferred. The firstquantitative work led to the formula HgHeIo, but from one of aseries of subsequent experiments, where the pressure changes werealmost negligible, the formula HgHe or HgHe, was deduced fromthe density of the gaseous mixture, measured with an Aston micro-balance, and the weight of mercury obtained by decomposing thecompound on a heated platinum spiral and weighing the resultantmercury with a special microbalance.As it was not possible tocondense the supposed helide a t the temperature of liquid air, theyield was increased by the use of various synthesisers, of which themost efficacious was a form of Siemens ozone-generator containingplatinised asbestos, the optimum gas pressure being 6 mm. Althoughthe compound was rapidly resolved into its constituents by anintense beam of ultra-violet light, an expected absorption line wastwice obtained, whilst further evidence confirming the synthesis wasobtained from interferometer measurements .25While the above work is obviously of a preliminary nature andshould be received with caution, the formation of compoundscorresponding with the hydrides appears possible on the assumptionthat the helium can exist in a hydrogen-like form, in which oneelectron is relatively far from the nucleus 26 and the scintillationsobserved in a zinc sulphide screen after helium had been passed overa radioactive deposit in a high-frequency discharge-tube may beattributed to this cause, and not to radium emanation or impuritiesin the gas.Further development of these new attacks on the" inert " gases will be awaited with interest.23 W. H. Keesom and M. Wolfke, Compt. rend., 1927, 185, 1465; A.,1928, 469; idem, Proc. K. Alcad. Wetensch). Amsterdam, 1928, 31, 90;A,, 696.24 L. I. Dana and H.K. Onnes, ibid., 1926, 29, 1060; A., 1927, 101.26 J. J. Manley, Phil. Mag., 1927, vii, 4, 699; A., 1928, 256.26 D. M. Morrison, Proc. C a d . Phil. SOC., 1928, 24, 268; A., 684INOWAHIC UHEMISTRY. 41Group I .Investigations of the action of hydrogen under pressure2' havebcen extended to aqueous solutions of lead nitrate : reactioncommences a t 130-150°, and a t 250" a series of basic salts areproduced along with increasing proportions of lead oxide as thetemperature is raised. The hydrolysis liberates nitric acid, but thisdoes not accumulate in the solution since it is reduced by hydrogen :thus the previous addition of nitric acid merely delays the reactionsbut does not affect the ultimate products. Gold surfaces acceleratethe reduction of nitric acid : hence in gold tubes at 250" and 80 atm.initial pressure, crystalline, blood-red lead oxide, d 8*59-8.79, isproduced, whereas in quartz tubes under similar conditions therequisite temperature is 300" or more.At 260-270" in quartztubes yellow lead oxide is formed in thin, crystalline leaflets, whilst at300" and 200 atm. initial pressure colourless lead oxide results. Theseparation of metallic lead occurs a t 250-275" and upwards,according to pressure. Water in the absence of hydrogen has noappreciable action on the precipitates.28Prom a comparison of the densities of the hydrides of sodium,d 1.38, potassium, d 1.47, rubidium, d 2.60, and cmium, d 3.42, withthose of the respective metals, it appears that union with hydrogencauses a contraction of the metal lattice which increases with theatomic volume of the metal.This effect is even more pronouncedin this case than with the hydrides of the alkaline-earth metals, butin both groups the molecular volumes approximate to those of thecorresponding fluorides, and the lattices may be assumed to be of therock-salt type.29 The heats of formation of the hydrides of cerium,praseodymium, and lanthanum have been shown to differ verylittle from those of the alkaline-earth compounds, but whereas thelatter substances are considerably denser than the correspondingmetals, the reverse is true of the hydrides of the rare earths andtitanium, zirconium, and vanadium, which show similarity in severalways and are by their semi-metallic nature a t once sharplydifferentiated from the salt -like hydrides formed by elements of thefist and second groups and from the metallic hydrides of the metalsof Group VIII.3OPure hydrogen peroxide has do" 1.4649, whilst for solutions con-taining A% by weight d = 0.9486 + 0.0051638, provided A is 95or more.The pure liquid shows a great tendency to supercool and27 Ann. Reports, 1926, 23, 53; 1927, 24, 42.28 V. Ipatiev and V. Ipatiev, jun., Ber., 1928, 61, [B], 624; A., 603.2p M. Proskurnin and J. Kasarnov&i, 2. anorg. Chern., 1928,170, 301 ; A.,30 A. Sieverts and A. Gotta, Z . anorg. Chern., 1928, 172, 1 ; A., 712.B 269742 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.for correct determination of the m. p. ( - 0.89") must be kept within0.1" below that temperature and continuously stirred31Anhydrous lithium sulphite has been isolated, the existence ofthe monohydrate confirmed, and derivatives with acetone, acet-aldehyde, and benzaldehyde prepared ; but all attempts to isolatethe hydrogen sulphite have been unsuccessful.32The chemiluminescent combination of sodium vapour withchlorine at pressures of about lo3 mm.has been studied by allowingthe vapour and the gas to stream into the opposite ends of a tube100 cm. x 3 cm., whereupon reaction took place over 10-20 cm.of the tube length with the deposition of sodium chloride which wascollected on a series of adjacent glass rings. At the pressures used,each molecular encounter resulted in reaction, so the reactionvelocity could be calculated from the precipitate distribution.Thecorresponding light distribution along the reaction zone was deter-mined photographically, and the efficiericy calculated by comparingthis distribution with the reaction-rate distribution. It is con-cluded that the reaction occurs in the gas phase, the primaryreaction, Na + C1, --+ NaCl + C1, being non-luminescent ; theemission arises from the secondary reaction, Na,, + C1 _jl NaCl +Na, in which the NaCl molecule retains the reaction energy, and bycollision transmits this energy to a free sodium atom. It is estimatedthat the second-reaction proceeds 1000 times faster than the first.%A most interesting piece of worka on the isotopes of potassiumhas been reported, affording evidence that, of the isotopes ofpotassium, K41 is mainly, if not wholly responsible for the radio-activity of the element.The matter is dealt with fully in theReport on Radioactivity,35 but it may here be recorded that if thisconclusion is correct the p-ray change of potassium will give rise toan isotope of calcium, Ca4I, which should be present in detectableamounts in potassium minerals.Determinations of the vapour density of potassium at 950" by aspecial modification of the Victor Meyer method have shown thatthe ratio [KJ/[K] does not exceed 5 x ; hence it appears thatthe alkali metals probably contain only about 2% of diatomicmolecules at their boiling points. Following a re-examination ofthe band spectra of these metals, absorption spectra of their mixed31 A.C. Cuthbertson, G. L. Matheson, and 0. Maas, J. Amer. Chem. SOC.,1928,50, 1120; A., 577.s2 J. A. N. Friend and D. W. Pounder, J., 1928, 2245; A., 1103.33 H. Beutler and M. P61&nyi, 2. Phykk, 1928, 47, 379; A,, 491.34 G. von Hevesy, Nature, 1927,120,838; A., 1928, 4; G. von Hevesy andM. Logstrup, 2. a m g . Chem., 1928,171,l; A., 684; M. Biltz and H. Zeigert,Phy8ikaE. Z., 1928,29, 197; A., 464.Seep. 308INORGANIC CHEMISTRY. 43vapours were obtained, and as metals having a measurable pro-portion of polyatomic molecules show bands in their absorptionspectra, the bands here found afford evidence that the alkali metalsform a complete series of binary molecules with each other in thevapour state.36In the presence of cupric oxide as catalyst mixed with potassiumor sodium hydroxide, potassium nitrate may be reduced to nitriteby hydrogen at 440480" or by carbon monoxide or water gas at220--400", the yields being 96, 65-70, and 70-76y0 respectivelyof the theoretical amount.37If copper is heated with twice its weight of sulphuric acid at 130-170" the chief reaction is 6Cu + 6H2S04 --+ 4CuSOp + Cu2S +SO +6H20,3* whilst a t 270' with excess of acid the reaction isCu + 2H2S04 + CuS04 + 2H20 +A careful investigation has been made of the solubility of hydrogenin silver foil (0.40 and 0.12 mm.thick) between the temperatures200" and 900" and a t pressures from 5-80 cm. Below 400" thesolubility is extremely small ; the absorption Q increases rapidlywith rising temperature, the values of log Q being practically a linearfunction of temperature, whilst at constant temperature the ratiodP/& is a constant.From Henry's law it follows that the dissolvedgas must be dissociated into atoms, or else it must exist in the formof a dissolved hydride containing one atom of hydrogen to themolecule.40Electrolysis of concentrated silver fluoride solutions with highcurrent density yields a t the cathode pure silver, whereas with lowcurrent density pure crystalline silver subfluoride, d 8.57, is obtained,which is decomposed by water into silver and silver fluoride butis unattacked by concentrated silver fluoride solutions. Whenheated, even in the complete absence of water, silver subfluoridedecomposes to pure silver and fluorine and thus furnishes a methodfor the preparation of fluorine.The subfluoride crystals conductelectricity, and in contact with silver wire act as rectifiers.41By electrolysis, using platinum electrodes in a divided cell withS-lOyO solution of silver nitrate containing 40% of pyridine asanolyte and 10-15% sulphuric acid as catholyte,42 an unstable,36 J. M. Walter and S. Barratt, Proc. Roy. SOC., 1928, [ A ] , 119, 257; A., 812.37 J. Milbauer and V. JudeniE, Chem. Obzor., 1926, 1, 16; idem, Chem.Zentr., 1927, ii, 1338; A,, 1928, 252.38 J. G. F. Druce, Chern. News, 1928,136, 81; A,, 378.39 G. Fowles, &id., p. 257; A,, 602.40 E. W. R. Stoacie and F. M. G. Johnson, l'roc. Roy. SOC., 1928, [ A ] , 117,41 A. Hettich, 2. anorg.Chem., 1927, 167, 67; A., 1927, 1165.4 2 G. A. Barbieri, Ber., 1927, 60, [B], 2424; A., 1928, 139.662; A,, 22944. ANNUAL REPORTS ON THE PROGRESS OF CHEM'ISTRY.orange-red crystalline compound, Ag(N0,),,4C5H5N, is produced insmall yield, the silver being bivalent. It liberates iodine frompotassium iodide and oxidises chromium and manganous salts tothe chromic and permanganic condition.A series of double thiosulphates of silver with the alkali metalsand ammonium has been prepared by the gradual addition of aqueoussilver nitrate to an ice-cold, well-agitated solution of the appropriatethiosulphate. The sparingly soluble compounds separate directlyfrom the mixture, whilst the more freely soluble may be precipitatedby the addition ofWhen a dilute solution of silver nitrate is treated with sodiumcarbonate and potassium persulphate at 70-80" silver peroxide isprecipitated ; in the presence of an iodate, almost homogeneous silverperiodate, AgJO,, is nearly quantitatively precipitated in place ofthe oxidc.44Qroup I I .A new, simple, and direct method of purifying beryllium will bewelcomed by those who have tried the older methods.Thepowdered oxide is placed between two perforated plates in a silicatube and heated in a current of carbonyl chloride at 450" for 1-2hrs., whereby iron and aluminium are removed as volatile chlorides.Calcium chloride and any beryllium chloride may then be removedby washing with water, and the residue is pure beryllium oxide.45By dissolving beryllium in a liquid ammonia solution of potassium,a potassium ammonoberyllate [empirically KBe(NH,),] is obtainedas a colourless solid vigorously hydrolysed by water and resemblingthe corresponding aluminate rather than the magnesiate : a sodiumsalt may be similarly obtained. Beryllium cleansed with a liquidammonia solution of ammonium chloride is insoluble in pure liquidammonia but dissolves slowly when sulphur is present in solution,forming a yellow precipitate of ammoniated beryllium mono- orpoly -sulphide .46 Ammoniated beryllium halides, BeCI,, 4NH,,BeC1,,2NH3, and BeBr,,4NH3, have been obtained by dissolvingberyllium in liquid ammonia containing an excess of ammoniumhalide, whilst ammonobasic beryllium salts,3Be(NH2),,BeI,,4NH3, 3Be(NH2),,BeBr,,4NH3,3Be(NH,),,BeBr,,8NH3, and 5Be(NH2),,BeI,,4NH3,have been prepared by the action of liquid ammonia solutions ofnormal beryllium halides on metallic beryllium.4'43 A.Rosenheim and G. Trewendt, Ber., 1928, 61, [BJ, 1731 ; A., 1199.44 G. A. Barbieri, Ber., 1927, 60, [B], 2427; A,, 1928, 142.4 5 E. Chauvenet and E. Duchemin, Cornpt. rend., 1927,185, 716; A., 1927,46 F. W. Bergstrom, J . Amer. Chem. SOC., 1928, 50, 652; A,, 493.47 Idem, ibid., p. 657; A., 493.1155INORGANIC CHEMISTRY. 45Calcium carbide reacts slowly at the ordinary temperature withbromine, about SO-90~o of the carbon being converted into hexa-bromoethane after 3.5 months, but a t higher temperatures freecarbon only is formed. Chlorine at the ordinary temperature yields3-5% of hexachloroethane, further attack probably being preventedby the layer of calcium chloride formed on the surface of the carbide.Very little reaction occurs with iodine at the ordinary temperature,but 35-37 yo of tetraiodoethylene, together with considerableamounts of free carbon, are obtained after heating a t 100-160" insealed tubes for some hours.A 20% yield of carbon disulphide andmuch carbon are obtained when calcium carbide and sulphur areheated at 270", but only traces of the disulphide are formed at 500".It is suggested that these reactions are preceded by adsorption andbegin with the formation of calcium halide or sulphide and carbon;the carbon may then either polymerise or react further to formhalogen compounds or carbon disulphide.The yields are deter-mined by the ratio of the three reactions concerned, for if polymerisedcarbon accumulates, the carbide becomes coated with a layer ofcarbon and the f i s t reaction is prevented.48The reaction of calcium with nitrogen is autocatalytic and is mostrapid with the finely divided metal such as results from the decom-position of calcium hexammine at low temperature and pressure.The speed of the reaction rises to a maximum at 450", falls to zeroat 600", and increases again beyond the melting point of calcium.Except at low temperatures, in which case there is a deficit of2-3%, the amount of nitrogen fixed corresponds with the formulaCa,N,, and the pressure of nitrogen evolved on reheating is highest ifthe original nitride is prepared at a low temperature, if reheating israpid, and if the time between the two operations is short.Thenitride may be black, bluish-black, reddish-brown, green, or yellow,according as it is prepared at 350", 350-600", 600--850", 850-1100",or above 1100", respectively, and each type has a particular dissoci-ation pressure, the dissociation of the yellow variety alone beingreversible. The black nitride is pyrophoric. These phenomena maybe explained by the assumption that the unstable combination CaNis formed at low temperatures and then decomposes irre~ersibly.~~The dissociation pressure of strontium carbonate lies on a curvesimilar to and between the curves for calcium and barium carbonates.Extrapolation gives 1258" as the temperature at which the dissoci-ation pressure is one atmosphere.No evidence of the existence ofa basic carbonate has been found.50 Hydrogen chloride diminishes4 8 E. Biesalski and H. van Eck, 2. angew. Chem., 1928, 41, 720; A., 852.49 P. Dutoit and A. Schnorf, Compt. rend., 1928,187, 300; A,, 1103.50 E. 0. Jones and M. L. Becker, J . , 1927,2669; A., 1928, 1946 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the solubility of radium chloride to a greater extent than that ofbarium chloride, whilst radium chloride does not influence appreci-ably the solubility of the barium salt. These facts underlie anindustrial treatment of certain ores whereby the saturated solutionof mixed chlorides is saturated with hydrogen chloride and theprecipitate so obtained, containing all the barium and radium, issubjected to a fractional precipitation by the same mean~.~1The existence of a tradtion point in zinc at 175" has now beenconfkmed by microscopical examinati~n.~ZThe white additive compound, 3Hg12,4m3, produced by theaction of excess of ammonia on Hg12,2NR3, dissolved in 10%ammonia at 21" deposits microscopic dark purple crystals ofHg9N,I, by the reaction 3(3Hg12,4NH,) + nNH3+ Hg9N,I, +12NH,I + (n - 4)NH3.53 Mercury reacts vigorously with ammon-ium persulphate in concentrated ammonia solution with the form-ation of mercuric tetramminopersulphate, [ Hgn ( NH3),]S,08 , whichloses ammonia in air but can be recrystallised from concentratedammonia solution.54Group I I I .Boric oxide, prepared by dehydrating boric acid below 800",pouring into carbon tetrachloride a t 0", and powdering, is a rapidand efficient drying agent until it has absorbed 25% of its weight ofwater, corresponding to the formation of metaboric acid.If thedehydration temperature exceeds 800", the product exhibits aninduction period which is probably due to the formation of molecularc0rnplexes.~5The critical temperature of boron trichloride, previously undeter-mined, is given as 178-8" & O.ZO.56Work on boric acid and the alkali perborates previously reported 5'has been continued with special reference to the solid alkali per-borates. By the addition of ethyl alcohol to a solution of lithiummonoborate and hydrogen peroxide, lithium perborate, LiB03,2H,0or LiBO2,H2O2,H2O, was precipitated, from which, by recrystallisationfrom water or by careful dehydration, the lower hydrate, LiB03,H20or LiB02,H202, was obtained.Purther dehydration by heating a tA. G. Eliseev, Ann. Inst. Anal. Physico-Chim. Leningrad, 1926, 3, 443 ;A., 1928, 31.62 G. I. Petrenko, 2. anorg. Chern., 1927, 167, 411 ; A., 1928, 10.63 M. Franpois, Cornpt. rend., 1928, 186, 1206 ; A., 603.54 F. Fichter and S. Stern, Helv. Chim. A&, 1928, 11, 754; A., 971.5 5 J. H. Walton and C. K. Rosenbaun, J. Ame~. Chern. Xoc., 1928,50, 1648 ;5 6 T. W. Parker and P. L. Robinson, J . , 1927, 2977; A., 1928, 114.A., 852.Ann. Repork, 1927, 24, 48INORGANIC CHEMISTRY. 47100" in a vacuum causes the substance to lose active oxygen, andsimultaneously to acquire the property of reacting with water withthe liberation of oxygen, possibly owing t o the formation of(LiB02),,02, and ultimately the monoborate remains. The completechange in crystal structure attending the formation of the mono-borate suggests that the original compound cannot be regardedmerely as monoborate with hydrogen peroxide of crystallisation.Ammonium and potassium perborates apparently exist only ashemihydrates, KB03,0-5H20, and attempts to remove this water byheating lead to their decomposition, as with the lithium salt.It isinferred that the only true alkali perborate is the anhydrous sodiumsalt containing a boron atom with the co-ordination number 3; theother alkali perborates are regarded as salts of dibasic acids con-taining two boron atoms with the co-ordination number 4, the lithiumand hydrated sodium salts having the formula M2( B,06,2H,0) andthe potassium and ammonium salts M,(B,06,H20).68Silver ultramarine, Ag,A16si6030s3, is obtained by heating silvernitrate in a sealed tube at 120-130" with ultramarine.From thisproduct a series of alkali, alkaline-earth, and even alkyl (n-butyl)ultramarines has been prepared by heating it with solutions of theappropriate chlorides or, preferably, i0dides.6~A description has been given of the preparation of the indiumoxides : In203 by igniting the hydroxide to constant weight, In,Oby the action of a reducing gas at 500" on In203 followed by sublim-ation in a high vacuum a t 650-750", and In0 as a residue fromthe last operation.60 The properties of these oxides are recorded,and also the preparation and properties of the correspondingsulphides.The problem of the molecular structure of thallium tri-iodide hasbeen investigated by examining (a) its reactions in methyl alcohol oracetonitrile, in which it exhibits the general reactions of a thallicsalt, and (b) the absorption spectra of the tri-iodide and severaladditive compounds, which all show two bands separated by1400 A.U., whereas substances containing the tri-iodide ion give twobands separated by 650-720 A.U.It is inferred that in thalliumtri-iodide the iodine atoms are not present as a tri-iodide ion, butare joined, a t least in part, by covalent linkages directly to themet al.611927, 16'7, 193; A., 1928, 32.1927, 30, 885; A., 1928, 463.6* H.Menzel (with J. Meckwitz and W. Kretzschmar), 2. anorg. Chem.,59 F. M. Jaeger and F. A. van Melle, Proc. K . Akad. bvetensch. Amaterdam,6o A. Thiel and H. Luckmann, 2. anorg. Chem., 1928, 172, 353; A., 852.6l A. J. Berry and T. M. Lowry [with (Mrs.) R. R. Goldstein and F. L.Gilbert], J., 1928, 1748; A., 107148 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Group IT. Group 111.A. 13.Ct3B.InSa, Eu, GdLaDY, Ho, Er,Tu, Yb, LuUaThe Bare Earths.From a consideration of solubility data and of the magnetic ionicmoments a’s a function of the number of electrons in the tervalentGroup IV.A. B.SnTbCe, Pry Nd, I1Hfion, the rare-earth metals are inserted in the periodicfollows :table asGroup V.A.TaPb T1 I 11 j Hg IIt is claimed that this scheme places the whole of the elements ofthe rare-earth group into MendelBev’s periodic system withoutdestroying its symmetry or impairing its utility in the slightest, andthat whilst rigorous testing is difficult because of the lack of manyessential data, a broad line taken through those available confirms,in general, the proposed arrangement. It will be remarked thatthe new arrangement does not change the position of the rare earthsin the table as usually accepted but simply gives a more detailedstatement of their distribution in that position.62An attempt has been made to determine the analogies whichexist between the compounds of scandium and those of othertervalent elements, the iron and the rare-earth groups.In thesolubility of its salts it resembles the elements of the rare earths, butit also exhibits many close analogies with the iron group; thus theacetylacetonates are isomorphous with those of iron, and the doublealkali sulphates with those of aluminium, whilst it forms a seriesof double alkali sulphates corresponding with the anhydrous alums,which are quite unknown in the rare-earth series; its basic nitratesclosely resemble those of chromium. Spectroscopic evidence usingthe acetylacetonates confirms its relationship with the aluminiumfamily. No such intimate relationship is found, however, betweenthe simple salts of scandium and those of either the rare-earth orthe iron group of elements, scandium occupying a transitional positionbetween the two groups.A study of numerous new salts of gadolin-ium and europium, similarly directed, shows that these elementsresemble both the cerium and yttrium groups of the rare-earthelements and form a transition between the two groups.63The use of perchloric acid, in preference to nitric acid, in the separ-62 J. F. Spencer, J . Amer. Chem. Xoc., 1928, 50, 2G4; A., 461.63 P. B. Sarker, Ann. Chim., 1927, [x}, 8, 207; A., 1928, 32INORGANIC CHEMISTRY. 49ation of various members of the rare-earth group has been advocated,and a number of perchlorates and hexa-antipyrineperchlorates havebeen prepared and de~cribed.~*The anhydrous chlorides of lanthanum, cerous cerium, praseo-dymium, neodymium , samarium, dysprosium, yttrium , holmium ,and thulium have been prepared by dehydrating the hexahydratesa t 100-200" in a stream of hydrogen chloride under reducedpressure.Melting points, densities, and pH values in solution havebeen recorded,65 the last confirming (except in the case of dyspros-ium, which appears more basic) the order of basicity given byHopkins.Neodymium selenate and its penta- and octa-hydrates have beenprepared, and evidence of the existence of a dodecahydrate has beenobtained .66Work on the displacement of spectra occurring during compoundformation has been ~ontinued.6~ It is based on the hypothesis thatthe electrostatic attraction of the kation for electrons of theremaining sheaths becomes more pronounced when the anion involvesthe valency electrons of the kation with greater intensity and con-sequently draws these sheaths towards the nucleus: hence con-traction occurs, the paths of the vibrating electrons becomingshorter, light of a shorter wave-length is emitted, and a displacementof the spectrum towards the ultra-violet takes place.This displace-ment is very marked in the series anhydrous iodide, bromide,chloride, and fluoride of praseodymium. Since the anhydrouscompounds can unite with water, ammonia, etc., by means ofresidual affinities, the atom does not exert its full chemical affinityin them. This is, however, fully displayed in solution, when the atomis freed from the circle of restricting atoms, and the contractionthereby caused explains the observed displacement of the spectrumtowards the violet.Another aspect of the matter is that thelessened importance of the anion, by reason of electrolytic dis-sociation, accounts for the disappearance of the difference in positionof the lines observed in the solid salts.68 This interesting inquiryhas been further extended to praseodymium salts of oxygenatedacids, the observations on which tend to support the foregoinghypothesis .69A., 494.64 E. M7ilke-DOrfurt and 0. Schliephake, 2. anorg. Chem., 1928, 170, 129;6 5 J. H. Kleinheksel and H. C. Kremers, J. Amer. Chern. SOC., 1928, 50,6 6 J. A. N. Friend and A. A. Round, J., 1928, 1820; A., 972.6 7 F. Ephraim and R. Bloch, Be?-., 1926, 59, [B], 2692; A., 1027, 121.69 Idem, idid., p. 72 ; A., 217.959 ; A,, 603.Idem, ibid., 1928, 61, [B], 6 5 ; A., 21750 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Group I V .Graphitic acid, prepared from Ceylon graphite, is crystalline andhas a well-defined X-ray spectrum somewhat similar to that ofgraphite.When heated cautiously to about 200" it decomposesexplosively, yielding incipiently crystalline, voluminous '' carbon I, "which differs from graphite in the closer proximity of the inter-ference lines (002) and (111). Decomposition at 200" under pressuregives the more distinctly crystalline " carbon I1 " having a spectrumclosely approximating to that of lustre carbon prepared at goo",except that again the same interference lines are closer, whilstdecomposition under sulphuric acid a t 150" produces the morehighly crystalline " carbon 111," in which the arrangement is similarto that in retort graphite.These products from graphitic acid differfrom lustre carbon and retort graphite in the remarkable sharpnessof their interferences.'*By shaking carbon disulphide with 0.8% sodium amalgam, extract-ing the product with 90% alcohol, and treating the extract withmethyl sulphate, it has been possible to obtain : methyl tetrathio-oxalate, (CS*SMe),, m. p. 100.9", b. p. 2lOo/0.1 mm. (decomp.), @*1.619, hydrolysed t o oxalic acid ; methyl methylxanthate, C3qOS2,b. p. 168"/765 mm., converted by alcoholic ammonia into ammoniumthiocyanate ; methyl trithiocarbonate, b. p. 224"/760 ; an isomericmethyl tetrathio-oxalate, m.p. 71.6", d:' 1.658, apparently stereo-isomeric with that described above ; tetramethylthiolethylene,(SMe),C:C(SMe),, m. p. 61.5", di!* 1.397, which gives a correspondingbromo-derivative, C,H,,Br,S,. The production of methyl methyl-xanthate is due to a subsidiary reaction, since the compound is notproduced when the crude product of the reaction is treated directlywith methyl sulphate. Carbon disulphide appears to be able t ocombine additively with sodium, giving *CS*SNa and :C(SNa),, butthe mechanism is not yet explained. A solution of sodium in liquidammonia reacts vigorously with carbon disulphide, producing abrown mass which, with methyl sulphate, yields methyl tetrathio-oxalate, methyl trit hiocarbonat e, t e t ramet h ylt hiolet h ylene, andmethyl sulphide.'lSolid azido-carbon disulphide reacts explosively with chlorine andbromine, although not with iodine.By carrying out the formerreactions in cooled, non-aqueous solutions, the monohalogenoazido-dithiocarbonates, XS*CS*N,, are probably produced, whilst by theaction of bromine in ethereal solution on silver azidodithiocarbonatethe tribromo-derivative results, Br,S*CS=N,. On hydrolysis with'O U. Hofmann, Ber., 1928, 61, [B], 435; A., 379.'l B. Fetkenheuer (with H. Fetkenheuer and H. Lecus), Ber., 1927, 60, [B],2528; A., 1928, 141INORQANIC CHEMISTRY. 51potassium hydroxide, the monobromo-compound gives potassiumazidothiocarbonate, KSGS-N,, and this salt in concentrated aqueoussolution gives immediately with iodine a heavy blackThe thermal equilibrium of carbonyl bromide even a t theordinary temperature lies well in favour of the components and isattained very slowly from carbon monoxide and bromine, but thecompound may readily be prepared by heating a mixture of carbontetrabromide and concentrated sulphuric acid (d 1433) a t 150-170",and purifying the distillate by two distillations following treatmentswith mercury and powdered antimony, respectively.The colourlessliquid, 615' 2.52, is stable up to about 150", is less readily hydrolysedby water than the corresponding chloride, and has a similarphysiological action.73A number of water-soluble salts are insoluble in acetic acid, and inthis solvent, as double decomposition occurs as readily as in water,certain sulphates which normally form hydrates can be precipitatedin the anhydrous condition.Certain metal acetates behave inacetic acid as do the corresponding bases in water; thus zincacetate is insoluble but dissolves readily when sodium acetate isadded .74The statement that ultra-violet absorption spectra indicate theformation of considerable quantities of gaseous silicon monoxideduring the reduction of the dioxide by carbon at 1500" is of interestas being, apparently, the first evidence for the existence of a loweroxide.75Melts of the composition Na,S,08 (orthotrisilicate) and Na,Si,O,(metatrisilicate) give on crystallisation Na,SiO, + Na,Si,O, andNa,Si,O, + SiO,, respectively; the dehydration of silica gel byacetone indicates the presence only of H2Si,0,; and the precipit-ation of sodium metasilicate, disilicate, or hydrogen silicate withbarium chloride gives a mixture of barium metasilicate anddisilicate except in the presence of large excess of sodium hydroxide,in which case the former only is produced. From these facts it isinferred that SiO," and Si,05" are the only anions present in solutionsof alkali silicates, and that the equilibrium is usually largely infavour of the disilicate A similar inference is drawn from theexhaustive extraction of water from preparations of hydrated silicawith liquid ammonia in a special extraction apparatus.For meta-72 W. H. Gardner and A. W. Browne, J . Amer. Chew,. Sac., 1927, 49, 2759;A,, 1928, 34.73 S. Lenher and H.J. Schumacher, 2. phy&kaE. Chem., 1928, 135, 85 ; A.,847 ; H. J. Schumacher and S. Lenher, Ber., 1928, 61, [B], 1671 ; A., 1200.74 A. W. Davidson, J . Amer. Chew. Sac., 1928, 50, 1890; A., 947.7 2 K. F. Bonhoeffer, 2. physikal. Chem., 1928,131, 363; A., 379.713 R. Schwarz and H. Richter, Ber., 1927,60, [B], 2263; A., 1928,3352 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.silicic acid, the product has the composition 6Si02,2H20,4NH3 at- 78.5", but with rise of temperature it loses ammonia in stagesof one molecule, yielding finally 6Si0,,2H20,NH,, stable at theordinary temperature. These results support the view that theminimum molecular formula for the acid is 6Si02,6H20. Partlydehydrated metasilicic acid preparations give the same compounds,whilst disilicic acid yields the product 2Si02,H,0,NH3, which,since it loses ammonia in a continuous and not a step-wise mannerwhen examined in the tensimeter, gives no evidence that the acid ismore complex than 2SiO,,H,O. Similar experiments with pre-parations having the composition of '' granitic '' (orthotrisilicic) andmetatrisilicic acids (respectively, 3Sio2,2H,0 and 3Si0,,H20) indi-cate that these are not definite compounds, and X-ray examinationsupports this view.77Well-defined substitution products, monoacetatomonoiodosiloxen,Si,03H,I( OAc), and diacetatodibromosiloxen, S~,O,H,B~,(OAC)~,have been prepared by adding to siloxen successive small amountsof a solution of the halogen in acetic anhydride, and removing theliquid phase from the solids in the reacting system before each newaddition of halogen ; otherwise, with bromine, only Si,O,H,Br,( OAc)is formed.Brominating in carbon disulphide and removing thehydrogen bromide yields successively tetrabromosiloxen, Si603H2Br4,and hexabromosiloxen, Si603Br6. These compounds are all yellowishsolids of unknown constitution.78 By their regulated hydrolysiswith 80% alcohol, or by the action of sulphur dioxide dissolved inacetone, the following hydroxysiloxens are obtained : Mono-[8i60,HS*OH, yellow], di- [Si,O,H,( OH),, brownish-red], tri-[Si,O,H,(OH),, red], tetra- [Si603H2(0H)4, brownish-violet], andhexa- [Si,O,(OH) 6, black]. Hexahydroxysiloxen is extremelyexplosive in air, this tendency increasing in these compounds withincreasing number of SiOH groups and Si-Si linking~.'~Germanium tetrafluoride is best obtained by the thermal decom-position of pure barium fluogermanate, prepared by dissolvinggermanium oxide in 48% hydrofluoric acid solution and adding asaturated solution of the theoretical quantity of barium chloride ;the granular precipitate, after drying at 120", rapidly evolves gaswhen heated at 700".The product, purified by fractional distillationat - 104", is a colourless, fuming gas, condensable at the temperatureof liquid air to a mass of white crystals which sublime when thetemperature is allowed to rise. Liquid germanium tetrafluoride7 7 W. Biltz, 2. Elektrochern., 1927, 33, 491; A., 379; W. Biltz and E.78 H. Kautsky and A. Hirsch, ibid., 170, 1 ; A., 496. '* H.Kautsky and H. Thiele, ibdd., 173, 116 ; A., 854.Raldfs, 2. anorg. Chem., 1928, 172, 273; A., 864IXORQANIC CHEMISTRY. 53exists at -115" under its own vapour pressure of 3032 mm. Whenpassed into water, the gas yields a t first a clear acid solution (fromwhich potassium hydroxide precipitates potassium fluogermanate)and later a gelatinous precipitate of hydrated germanium dioxideseparates. Glass in presence of moisture is rapidly etched by the gas,but quartz is not attacked below 700°, nor is there any evidence ofdissociation a t 1000".80Attempts to prepare germanium dichloride by reduction of thetetrachloride and other methods have failed, but reduction of amixture of germanobromoform and germanium tetrabromide by zincgives the dibromide as a colourless crystalline solid, which decom-poses (2GeBr, = Ge -b GeBr,) when heated, is insoluble in hydro-carbons, is soluble in a.lcoho1 and acetone, and is hydrolysed by waterto yellow, hydrated germanous hydroxide.It absorbs bromine toform the tetrabromide, and with hydrogen bromide yields germano-bromoform (m. p. -24" approx.). The di-iodide, obtained by theaction of concentrated hydriodic acid on an excess of a mixture ofhydrated mono- and di-oxides of germanium below 40°, is a yellowsolid crystallographically similar to lead iodide ; its solutions possessreducing properties; and on heating in a vacuum it yieldsgermanium and the tetraiodide.81The optimum temperature for the reduction of germaniumdisulphide to the monosulphide in a current of hydrogen is about480".The very hard, black crystals of the monosulphide arepractically insoluble in mineral acids, but are dissolved by fusedpotassium hydroxide or by prolonged digestion with aqueouspotassium hydroxide.82 Reduction of germanic salts with zinc and25% sulphuric acid produces brown germanous oxide, which isstable when dry and almost insoluble in hydrochloric acid. When,however, reduction is effected with hypophosphorous and hydro-chloric acids at 100" for 2 hours, followed by neutralisation in thecold with ammonia an orange-yellow hydroxide is obtained, which issoluble in alkalis and hydrochloric acid. The hydrochloric acidsolution yields the chloride (GeCl,), which is hydrolysed by waterto a white oxychloride, is a strong reducing agent, and gives withhydrogen sulphide the orange-red sulphideThe densities of ordinary lead chloride and uranium lead chloride(Pb = 206.05) are = 5.909 & 0.001 and 5.884 5 0.001, respec-tively, whence the identical molecular volumes, 47.07 c.c., areL.M. Dennis and A. W. Laubengayer, 2. physikal. Chem., 1927, 130,520; A., 1928, 33.*1 F. M. Brewer and L. M. Dennis, J . Physical CJhern., 1927, 31, 1526; A.,1927, 1156.82 L. M. Dennis and S. M. Joseph, ibid., p. 1716; A., 1928, 33.8s J. Bardet and A. Tchakirian, Compt. rend., 1928, 186, 637; A., 38054 ANNUAL REPORTS ON "HE PROGRESS OF CHEMISTRY.calculated. The densities of the saturated aqueous solutions differ,but the molecular volumes of the salts in these solutions are againidentical. Different increases in the refractive index of water arecaused by the addition of equal weights of the two salts, but themolecular refractivities of the dissolved salts are identical.Theequivalent conductivities of the almost saturated solutions arepractically equal and the heats of precipitation of the chromates areidentical.84Group v.Nitrogen trifluoride has been obtained by electrolysing fusedanhydrous ammonium hydrogen fluoride. It is a colourless gas atthe ordinary temperature, and, according to analysis and densitymeasurements, has the formula NF,. It is condensed by liquid airto a colourless mobile liquid which boils under atmospheric pressurea t - 119" and freezes below -210". Vapour-pressure measure-ments have been made between -125" and -194", and themolecular heat of vaporisation is calculated to be 2400 g.-cal.Nitrogen trifluoride is insoluble in water and unattacked by wateror hydrogen, but when sparks are passed through a mixture of thegas with water vapour, hydrogen fluoride and oxides of nitrogen areformed.With hydrogen under the same conditions the reactionis very violent, nitrogen and hydrogen fluoride being obtained.The gas is remarkably stable; it does not react with mercury,manganese dioxide, potassium hydroxide solution, or glass at theordinary temperature. 85Determinations of the parachor of a number of derivatives ofazoimide agree excellently with the calculated values for the cyclicform R*N<ir (if it be assumed that the double linking betweennitrogen atoms has the same value as C:C and the triple linking thesame effect as the acetylenic or CiN), and it appears that Thiele'sformula, R*N:NiN, is probably untenable.86Hydrazine is formed in appreciable quantities when pure aqueousammonia is passed through a strongly cooled high-tension arc andthen cooled at once with liquid air.It is suggested that themechanism of this synthesis is the union of NH3 and -NH, ratherthan the union of two NH, groups, because the probability of thelatter collision is very small when ammonia is present in greatexcess.*' Hydrazine hydrate and dilute selenic acid yield colourlesshydrazine hydrogen selenate ; the salt is stable in boiling water, buta4 W. A. Roth and 0.Schwartz, Ber., 1928, 61, [B], 1539; A., 942.8 6 0. Ruff, J. Fischer, and F. Luft, 2. anorg. Chern., 1928,172,417 ; A., 854.86 H. Lindemenn and H. Thiele, Ber., 1928, 61, [B], 1629; A., 937.8' G. Bredig and A. Koenig, Natumuiss., 1928, 16, 493; A., 864.NIN0BG)ANIC CHEMISTRY. 55when dry it explodes with unusual readiness by heat, shock, or con-tact with hydrochloric acid vapour. A large number of crystahecompounds of hydrazine with metallic sulphites and nitrites havebeen prepared by the action of hydrazine hydrate on solutions ofthe metallic bisulphites 88 or on solutions of the acetates in presenceof excess of sodium nitrite.The reaction of nitrogen peroxide with certain anilides indicatesthe constitution O:N*O*N02, whilst other reactions are consistentwith the simple formula OPNO,: it is therefore suggested thatthe liquid exists in these two tautomeric forms.89The reducing action of magnesium amalgam on metallic nitratesand nitrites affords a convenient method for the preparation ofhyponitrites.In general, magnesium amalgam is added slowly toa concentrated solution of the salt a t 5" or below, the magnesiumhydroxide being removed after a short time, and the reductionsimilarly repeated until the solution is free from nitrate andnitrite : it is then concentrated in a vacuum over sulphuric acid.A number of hyponitrites not hitherto described have thus beenmade, including the explosive oxyhyponitrite, Cd(OH)NO, whilst a60% yield of hydroxylamine sulphate of 9743% purity has beenobtained by the reduction of nitric acid in the presence of sulphuricacid.90Sodium hydronitrite, Na2N02, having an intense yellow colour,has been prepared by the interaction of solutions of sodium nitriteand sodium in liquid ammonia,91 and can be obtained also by sub-stituting lithium or potassium for sodium in this reaction or bycathodic reduction of sodium nitrite in liquid ammonia in a dividedcell.The alkali hydronitrites are stable when gently heated in avacuum or in nitrogen, but a t 100-130" decompose violently. Ofparticular interest is the fact that under certain conditions directaddition of oxygen to a hydronitrite may occur with formation ofan unstable, brown peroxide ( ? ) (Na2N0,),:02, which is decom-posed by water into oxygen, sodium nitrite and hydroxide, andhydrogen peroxide.Similarly, an atom of iodine is taken up froman ethereal solution, giving a black additive product which rapidlydecomposes into sodium nitrite and iodine. It appears probable thataddition of sodium to sodium nitrite occurs a t the oxygen ratherthan the nitrogen atom, and that the hydronitrites -N(ONa), arethus analogous to Schlenk's metallic ketyls.88 J. Meyer and W. Aulich, Ber., 1928, 61, [B], 1839; A., 1200; P. RByand B. K. Goswami, 2. anorg. Chem., 1928,168,329; A., 258.8s M. Battegay and W. Kern, BuU. SOC. chim., 1927, [iv], 41, 1336; A., 1928,31.9O P. Nmgi and B. L. Nandi, J., 1928, 1449; A,, 855.E. Zintl and 0. Hob, Ber., 1928,61, [B]? 189; A., 25856 A."IJA.L REPORTS ON THE PROGRESS OF UHEMISTRY.Allotropic modifications of phosphorus obtained under high tem-peratures and pressures in nitrogen in contact with metallic powdershave been described as consisting of purple (1.90, 4.4 mm., 200"),ruby (2.11, 1.4 mm., 346"), and black (2.7, <0.5 mm,, 490") forms,the figures in parentheses being the corresponding density, vapourpressure at 21", and inflammation point, respectively.These andwhite phosphorus form a continuous series of solid solutions, redphosphorus being a mixture of ruby and purple phosphorus, andviolet a mixture of the ruby and black varieties. Black and purplephosphorus form a eutectic.92Hexafluorophosphoric acid, HPF,, is formed by the hydrolysis ofdifluorophosphoric acid, HPO,F,, which is produced when phos-phoric oxide is dissolved in 40% hydrofluoric acid.Solutions of thepotassium salt give no precipitate with salts of the alkaline-earthor heavy metals. The PF', ions are very stable towards boilingwater and alkali hydroxide but are slowly decomposed by con-centrated acids. Nitrosyl fluoride and phosphorus pentafluorideappear to yield the crystalline compound NOF,.93It has been shown that phosphorus trioxide, prepared by themethod of Thorpe and Tutton, contains 1.5-2% of phosphorus,which may be eliminated by fractional crystallisation from carbondisulphide, exposure to light, and distillation. The pure oxidemelts a t 23-8", is unaffected by sunlight, and does not glow oroxidise in moist or dry oxygen at the ordinary temperat~re.~~A series of sodium thiophosphates has been prepared by the actionof sodium sulphide or hydrosulphide on phosphorus pentasulphideYg6and improvements have been described in methods for the electro-lytic preparation of perphosphates, resulting in the productionof Rb,P,O,, Ag4P,0,( ?), Ba2P,0,,4H20, Zn2P208,4H,0, andP b2P20 8.Q6Attempts have been made to increase the quantity of proto-actinium (element 91) available and about 2 mg. of the oxide,apparently fairly pure, have been extracted from Joachimsthalpitchblende residue^.^' It is pointed out that such material wouldform a valuable source of actinium, besides affording means ofstudying the special chemical properties of elements of atomicnumber 91 in relation to those of the lower members of the samegroup, niobium and tantalum, and of the neighbouring elements92 V.J. Nikolajev, Compt. rend., 1938, 186, 1621 ; A,, 827 ; V. Ipatiev andV. J. Nikolajev, Ber., 1928, 61, [B], 630; A,, 604.93 W. Lange, ibid., p. 799; A., 604.O4 (Niss) C. C. Miller, J . , 1928, 1847; A,, 972.95 H. E. Wallsom, Chem. News, 1928, 136, 113; A., 380.96 F. Fichter and E. Gutzwiller, HeZv. Chim. Achy 1928, 11, 323 ; A., 480.O 7 A. von Grosse, Ber., 1928, 61, [B], 233 ; A., 269ENORGANIC CHEMISTRY. 57uranium and thorium. Protoactinium is also interesting becauseelements of odd atomic number, especially in the last horizontalseries of the periodic table, are comparatively rare.98croup VI.The fact that the viscosity of sulphur is usually dependent onits previous thermal treatment is probably due to traces of sulphuricacid, hydrogen sulphide, or sulphur dioxide, which retard theattainment of inner equilibrium between the S, and SA varieties,for pure gas-free material, prepared by distillation in a stream ofcarbon dioxide, followed by distillation in a high vacuum, shows nosuch irregularity.From sulphur so purified, crystals of SI, (mother-of-pearl sulphur) separate readily, but rhombic sulphur could notbe obtained. The natural f. p. was found to be 103.8-103.9" andthe ideal ,111. p. about 107", whilst the liquid could be supercooled to80°, viscosity measurements being made a t that temperat~re.~~The chlorides of zinc, aluminium, ferric iron, and bivalent mercurydissolve in liquid hydrogen sulphide, and the last-named is thio-hydrolysed, depositing black mercuric sulphide which later turnsred. A similar action occurs with cuprous and silver chlorides.Boron trichloride yields white crystals of BCl,, 12H2S, carbon andsilicon tetrachlorides are miscible without immediate reaction,and phosphorus, antimony, and bismuth trichlorides give rise tothe following thio-salts : PSCl,, SbSCl,, and BiSCl,BiCl,.l Fromthe conductivity of solutions in hydrogen sulphide, particularly ofiodine, it is concluded that the solvent is an ionising medium.2Hydrogen pentasulphide has been prepared from pure ammoniumpentasulphide by treatment with anhydrous formic acid: it is athin, clear yellow oil, d16" 1.67, which on cooling becomes suddenlyviscous at -225" and a glassy solid a t -50".It has also been shownthat ammonium pentasulphide on distillation in a Faraday tubeyields ammonium monosulphide, not the disulphide as was previouslysupposed, and evidence has been obtained that the alleged ammoniumheptasulphide is a solid solution of sulphur in the pentasulphide.Thus there appears to be but one polysulphide of ammonium, thepentasulphide. By sublimation from a suspension of the penta-sulphide in carbon disulphide, pure orange-yellow ammonium thio-9 * 0. Hahn, Xitzungsber. Preuss. Akad. Wiss. Berlin, 1927, 275; A,, 1928,99 C. C. Farr and D. B. Macleod, Proc. Roy. Soc., 1928, [ A ] , 118,534 ; A., 578.A. W. Ralston and J. A. Wilkinson, J. Amer. Chem. Xoc., 1928, 50, 258;2 H.R. Chipman and D. McIntosh, Proc. Nova Scotian Inst. Sci., 1927,343.A., 381.16, 189; A., 1928, 84568 ANNUAL REPORTS ON THE PROGRESS OB CHEMISTRY.carbonate is obtained: from which it is possible to isolate trithio-carbonic acid, f. p. -30*5", &!* 1.47, y12'5' 48-3 dyneslcm.Potassium hexathionate has been prepared by the addition of asolution of potassium nitrite (1 mol.) and potassium thiosulphate(3 mols.) to well-cooled hydrochloric acid. The mixture is vigorouslyshaken until the colour passes through brown and green to yellow,after which nitrous fumes are removed by a current of air. after theseparation of precipitated potassium chloride the filtrate is con-centrated under diminished pressure, and potassium hexsthionate,mixed with chloride, separates.The hexathionate is stable whendry, but readily decomposes in aqueous solution ; acids stabilisethese solutions, and when much acid is present the hexathionatemay be crystallised or saltedSelenium tetrafluoride has been made by the action of seleniumtetrachloride on silver fl~oride.~ The compound has d 2.77, b. p.93", and m. p. -13.2", and is thus distinct from the oxyfluoride,prepared ti by using selenium oxychloride in a, similar reaction at140", which has d 2.67, b. p. 121-129", m. p. 4.6". Both liquidsattack silica and silicious materials with the formation of silicontetrafluoride together with selenium or selenium dioxide or both.An extended investigation has been made of the double salts ofselenic acid, for details of which the original paper should beconsulted.'An acid molybdate solution reduced with zinc when saturatedwith hydrogen selenide deposits molybdenum pentaselenide,Mo2Se5 ; and the diselenide, MoSe,, and sesquiselenide, Mo2Se3, havebeen prepared by dry methods.A solution of potassium molybdatein concentrated potassium hydroxide, when saturated with hydrogenselenide, deposits red needles of potassium selenomolybdate,qMoSe,. The sodium salt cannot be similarly prepared, butglistening, blue crystals of (NH4),MoSe4 are obtained in this wayfrom molybdic acid in concentrated ammonia.8 Similar treatmentof cold, concentrated ammonium tungstate solution with hydrogenselenide yields green orthorhombic crystals of ammonium seleno-tungstate, (NH,),WSe4, whilst incomplete saturation yields red,triclinic crystals of the diseleno tungstate, ( NH4),WSe20, .gIt is recorded that tellurium can be deposited in smooth, thick3 H.Mills and P. L. Robinson, J., 1928, 2326; A., 1200.* E. Weitz and F. Achterberg, Ber., 1928, 61, [B], 399; A., 381.5 E. B. R. Pridesux and C. B. Cox, J., 1928, 1603; A., 855.Idem, ibid., p. 738; A., 495.J. Meyer and W. Aulich, 2. anorg. Chem., 1928, 172, 321; K., 856.E. Wendehorst, ibid., 173, 268; A., 973.* V. Lenher and A. G. Fruehan, J . Arner. Chern. SOC., 1927, 49, 3076; A.,1928, 142TNOROANIU CHEMISTRY. 59layers with theoretical current efficiency from a bath containing300 g. of tellurium dioxide (49.6% TeO,, 46.1% Na,TeO,), 500 g. of48% hydrofluoric acid, and 200 g.of sulphuric acid per litre, 1.6amp./dm., being used at a lead cathode. With tellurium anodesthis bath can be used for refining tellurium, all selenium remainingin the anode slimes.lOA heliotrope double chloride, CrC13,HCl,xH,0 (where xis approxh-ately 6), is precipitated by passing hydrogen chloride through aconcentrated solution of green chromic chloride. The substance isinsoluble in alcohol or ether, but in water gives a pink solutionwhich immediately turns green.llBy'the action of pure carbon monoxide for 6 hours at 0" on puretungsten hexachloride in the presence of magnesium phenyl bromide,ether, and benzene, colourless laminated crystals of tungstencarbonyl, W(CO),, were obtained which sublimed at 50", and weredecomposed at 100" or by fuming nitric acid, but not by water orordinary acids.12Group VII.Magnesium perchlorate is applied as a convenient drying agentby soaking pumice granules in a 35% solution of the salt, and dryingfirst at 175" and finally a t 240" in a current of dry air.The materialhas greater capacity than phosphoric oxide, can be repeatedlyreactivated, and does not become sticky on handling or form channelsthrough use.13A salt of univalent manganese, Na,Mn(CN)6, is precipitated as amicrocrystalline powder, very sensitive to oxidising agents, when asolution of sodium manganocyanide is reduced by aluminium andsodium hydroxide, and the resulting solution is filtered into asolution of sodium hydroxide and sodium cyanide saturated withsodium acetate.The potassium salt may be similarly prepared, andvariations in the procedure afford similar salts containing a smallerproportion of alkali cyanide. The existence of K&h(CN), is highlyprobable, but if cyanide is used in the final washing of theprecipitates the K,Mn(CN), is invariably obtained.14Element No. 75, dvi-manganese or rhenium, the discovery ofwhich was reported in 1925,15 has been extracted from gadolinite,lo F. C. Mathers and H. L. Turner, Trans. Amer. Electrochem. SOC., Sept.,l1 J. R. Partington and S. K. Tweedy, J., 1927, 2899; A., 1928, 34.la A. Job and J. Rouvillois, Compt. rend., 1928, 187, 664; A,, 1201.1928, 54; Advance copy; A., 850.5. H. Yoe, R. W. McGahey, and W. T. Smith, Ind. Eng. Chem., 1928,20,686; A., 862.14 W.Manchot and H. Gall, Ber., 1928, 61, [B], 1135; A., 722.l5 Ann. Reporta, 1926, 22, 6360 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.alvite, columbite, and Norwegian molybdenum glance to theamount of 120 mg. : this has sufficed for a preliminary survey of itschemical and physical properties, which place the element betweentungsten and osmium in the Periodic Table.Metallic rhenium, obtained by reduction of the sulphide inhydrogen, is a heavy grey powder, unaltered at 2000" in a vacuum :it burns in oxygen at 300', forming two oxides, Re,O, and ReO,.The white heptoxide condenses to a colourless liquid which sets toa white solid, m. p. 26-30', sparingly soluble in water and acids;the less volatile trioxide condenses to a yellow liquid which solidifiesto form hygroscopic crystals, m.p. 160", and, above its boilingpoint, 450°, yields a vapour from which the heptoxide may becondensed. When reduced by carbon monoxide or sulphur dioxide,these oxides yield green, blue, and violet oxides, which, however, onprolonged heating are reconverted into the yellow or the white oxide.An aqueous solution of the yellow oxide, which is acidic, gives novisible change with hydrochloric, nitric, and sulphuric acids,potassium and sodium hydroxides, ammonia or oxidising agents, butwith barium hydroxide and silver nitrate it forms white precipitates,possibly BaReO, and Ag,ReO,, soluble in dilute nitric acid.Hydrogen sulphide is oxidised by the yellow oxide solution withdeposition of sulphur, but in the presence of acids a grey sulphide isquantitatively precipitated together with sulphur, and this precipit-ation is.not hindered by oxalic, tartaric, or phosphoric acid (dis-tinction from tungsten). By heating the precipitate in carbondioxide at 400-600" unstable black sulphides, Re,S, and ReS,,appear to be formed. Above 600°, the stable black disulphide,ReS,, is produced. An acidified solution of the yellow oxide willnot react with ammonium.phosphate or potassium ferrocyanide, norwill it give a colour with potassium xanthate. This behaviourserves to distinguish the element from molybdenum, as do also thebehaviour of the solution towards potassium thiocyanate and thegreater volatility of rhenium oxide as compared with molybdenumoxide.Absence of any reaction with potassium iodide distinguishesthe element from osmium. By heating rhenium in chlorine, twovolatile chlorides are formed, ReCl,, brown needles, subliming at150", hydrolysed by water ; and ( ?) ReCl,, green, more volatile thanthe lower chloride. With iodine and bromine vapour, respectively,dark volatile compounds are formed.16Work on the same material by Rontgen spectroscopy has shown a,content not exceeding 0.2% of elements lying between copper anduranium, and the L-series of rhenium has been thoroughly investig-ated. Careful examination of the ordinary spectrum indicates thatlti W. Noddack, 2. Elektrochem., 1928, 34, 627; A,, 1344INORaaNIC CHEMISTRY. 61the most persistent lines, especially the triplet at 3640 k, will serveto detect rhenium down to a concentration of and this shouldgreatly facilitate the collection of minerals containing this element -The metallic powder, d 10-4, has been melted in the carbon arc aswell as on the anticathode of the Rontgen tube; the metallic beadsresemble lead and are stable in air, and their density, obtained bymeasuring the diameter (0.05 to 0.1 mm.) and weighing on a micro-balance, is about 20.The melting point and boiling point areprobably higher than those of tungsten. The specific heat between0" and 20" is 0.0346, giving by the application of Dulong and Petit'slaw Re = 185. The exact determination of the equivalent isdifficult, as the precise composition of the materials used is uncertainby reason of the ease with which oxidation and reduction take place.The ratio Re : 0 gave in ReO,, Re = 189.8, but in Re,O,, Re =196.0, the difference being due in all probability to the readiness withwhich the heptoxide is converted into the trioxide.Analysis ofrhenium hexachloride gave Re = 189.2. The most trustworthyratio for atomic weight purposes is ReS, : Re, which gave as a meanof four determinations Re = 188.71 rf: 0.25. This determination iscarried out by precipitating rhenium from acid solution as ReS, withfree sulphur, melting this material with sulphur a t 350", andobtaining Re,S,, which by prolonged heating in carbon dioxide at900" yields the most stable sulphide, ReS,. The disulphide, heatedin hydrogen at lOOO", first forms ReS and is finally completelyreduced to the metal.17Group VIII.Iron pentacarbonyl in appropriate non-aqueous solvents reactswith halogens to give Fe(CO),I,, dark brownish-red, Fe(CO)*Brz,brown, and Fe(CO),Cl,, yellow, the last a t -20".These compoundscould not be made from ferrous halides and carbon monoxide, intowhich they are rapidly decomposed by the action of water. Thebromide loses carbon monoxide completely in the presence of 2 mols.of pyridine, but under precisely similar conditions the iodide affordsthe dicarbonyl compound, Pe(CO),I,,ZC,H,N, which loses carbonmonoxide completely when treated further with the base. Underthe influence of light the chloride is rapidly and completely decom-posed, whilst the iodide is less readily affected. The final productsof these decompositions are ferrous halides, which are thus readilyprepared in the pure state.l*A reinvestigation of the composition and properties of ferricsulphide has shown that when the washed precipitate of empiricalcomposition Fe,S, (formed by the addition of ammonium sulphide17 (Frau) I.Noddack, 2. EEektrochem., 1928, 34, 629.18 W. Hieber and G. Bader, Ber., 1928, 81, [BJ, 1717; A., 120262 ANNUAL REPORTS ON "HE PROGRESS OF CHEMISTRY,tlo a solution of ferric salt, containing tartrate) reacts in neutralsolution with mercuric or cadmium salts, it behaves as ferrous orferric sulphide, respectively. The explanation suggested is thatt'he substance is a mixture of the valency isomerides S:Fe*S*Fe:Sand FeS,FeS2.19 The dependence of the composition of the sulphideon conditions of precipitation previously worked out 2o is also validfor the mercaptides of iron, for whilst ordinary solutions of ferricsalts give ferrous mercaptide with ethyl mercaptan, if the con-centration of ferric iron is depressed by the addition of tartrate,ferric ethyl mercaptide results.Ferric sulphide has been shown to be the principal product of thereaction of ferric hydroxide with hydrogen sulphide a t 100" ; themono- and di-sulphides also present are believed to result from thepartial decomposition of this compound.21Considerations of space preclude even reference to a, great deal ofinteresting work done on the preparation of co-ordination and othercompounds of the metals of this group.Iridium hexa- and penta-fluorides have been prepared by thepassage of pure fluorine over the metal heated in a boat of calcinedfluorspar supported in a tube of the same material heated electrically.Vessels of fluorspar calcined at 1280", which are readily workedmechanically by means of an emery wheel, are resistant to fluorineat high temperatures.22The formation of a volatile platinum carbonyl chloride whcncarbon monoxide is passed over heated platinum chloride has beenapplied in the separation of platinum from kindred metals. Theplatinum carbonyl chloride decomposes at about 300" with theformation of platinum, carbon monoxide, chlorine, and carbonylchloride, and the metal may be recovered in a compact form on aplatinum wire heated a t about 600" in the vapour of the compound.23Systems and Equilibria.A great deal of work has been done on various types of systemsand equilibria which it is impossible to describe in this Report.Itmay be useful, however, to give here the titles in the order in whichthey appear in the Abstracts.Barium bromideradium bromide-hydrogen bromide-water 24 ;cuprous chloride-cupric chloride 25 ; sodium carbonate-sodiuml@ F. Feigl and E. Backer, 8. anal. Chem., 1928, 74,393; A., 1105.2o H. Ki-epelka and W. Podrouiek, Rec. trav. chim., 1925, 44, 416; -4.,21 T. G. Pesrson and P. L. Robinson, J., 1928, 814; A., 606.2s E. H. Reerink, 8. anorg. Chem., 1928,173, 45; A., 856.24 V. Chlopin and B. Nikitin, ibid., 1927, 166, 311; A., 1927, 1133.25 W. Biltz and W.Fischer, ibid., p. 290; A,, 1927, 1141.1926, ii, 703.0. Ruff and J. Fischer, 2. EEektrochem., 1927, 33, 660; A., 1928, 382INORGANIC CHEMISTRY. 63hydrogen carbonate-water 26 ; ferric nitrate-potassium nitrate-water 27 ; manganese sulphate-potassium sulphate-water ; manganese sulphate-ammonium sulphate-water ; copper sulphate-sodium sulphate-water 28 ; sodium oxide-arsenic oxide-water 29 ;magnesium sulphate-water 3O ; ethyl alcohol-carbon tetrachloride 31 ;aluminium nitrate-potassium nitrate-ferric nitrate-water 32 ; iron-copper-sulphur 33 ; copper sulphate-sodium sulphate-water ;sodium oxide-nitrogen pentoxide-water 35 ; potassium carbonate-sodium carbonate-water 36 ; mercuric iodide-potassium iodide-water 37 ; ferrous chloride-nickel chloride-water 38 ; manganousphosphate-phosphoric acid-water 39 ; water-sodium chloride-mag-nesium sulphate-magnesium chloride-sodium sulphate ; water-sodium nitrate-sodium chloride-sodium sulphate 41 ; aluminiumchloride-potassium chloride-hydrogen chloride-water 42 ; ferricchloride-aluminium chloride-water 83 ; thorium oxide-carbon ;aluminium oxide-carbon 45 ; ammonium dichromate-potassiumsulphate-potassium chloride ; ammonium dichromate-iron-sulphur 46 ; thallium-phosphor us 47 ; potassium oxalate-water 48 ;26 A.E. Hill and L. I<. Bacon, J. Amer. Chem. SOC., 1927, 49, 2487; A.,1927, 1142.2 7 G. Malquori, Atti R. Accad. Lincei, 1927, [vi], 5, 1000; A., 1927, 1142.28 R. &I. Caven and W. Johnston, J., 1927, 2358; A., 1927, 1142.29 A.Rosenheimand S. Thon, 2. unorg. Chem., 1927,167,l; A., 1927,1156.30 H. L. Robson, J. Amer. Chem. SOC., 1927,49,2772; A., 1928, 19.31 S. F. Calhoun and T. C. Poulter, Proc. Iowa Acad. Sci., 1926, 33, 169;32 G. Malquori, Guzzettu, 1927, 57, 663; A., 1928, 20.33 P. P. Fedot6ev (with D. N. Nedrigailov), 2. anorg. Chem., 1927, 167,34 R. M. Caven and W. Johnston, J., 1927, 2902; A,, 1928, 20.36 N. S. Kurnakov and V. J. Nikolajev, 2. physikul. Chem., 1927,130, 193;A., 1928, 19.329; A., 1928, 20.A,, 1928, 20.J. W. Bain, J. Amer. Chm. Soc., 1927, 49, 2734; A., 1928, 20.37 (Mlle.) M. Pernot, Compt. rend., 1927, 185, 950; A., 1928, 20.38 Y. Osaka and T. Yaginuma, 2. physika2. Chem., 1927,130,480 ; A., 1938,20.3* G. G r u b and M. Staesche, ibid., p.572; A., 1928, 20.40 A. Kiipper, Cdiche, 1927, 8, 467; A., 1928, 20.41 A. Chretien, ibid., 1926, 8, 390; A., 1928, 20.43 Idem, &id., p. 665; A., 1928, 20.4 p C. H. Prescott, jun., and W. B. Hincke, J. Amer. Chem. Soc., 1927, 49,46 Idem, ibid., p . 2763; A., 1928, 21.G. Malquori, ffazzetta, 1927, 57, 661 ; A., 1928, 20.2744; A,, 1928, 20.W. P. Jorissen and G. M. A. Kayser, 8. phyaikal. Chem., 1927,130, 482 ;A., 1928, 21.4 7 Q. A. Mansuri, J., 1927,2993; A., 1928, 129.40 N. K. Voskresenski, Ann. Inst. Anal. Physko-Chim. Leningrad, 1926, 3,468; A., 1928, 13064 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.copper acetate-acetic acid ; lead acetate-acetic acid-water 40 ;uranyl nitrate-alkali nitrate-water 5O ; barium carbonate-silicondioxide 51 ; lime-alumina-silica 52 ; ferrous oxide-ferric oxide-alumina-silica % ; calcium carbide-nitrogen 54 ; potassium dichrom-ate-sulphur-iron or aluminium 55 ; silica 56 ; iron-ferrous sulphide 57 ;zinc-antimony 58 ; sodium oxide-silica-water 59 ; sodium carbonate-ferric oxide 6o ; sodium sulphate-magnesium sulphate-water ;iron-nickel 62 ; sodium sulphite heptahydrate 63 J lead-tin ;potassium nitrate-calcium nitrate-sodium nitrate-water 65 ; ferricchloride+obaltous or nickel chloride-water ; cobaltous chloride-nickel chloride-water 66 ; calcium oxide-alumina-ferric oxide G7 ;sodium fluoride-barium fluoride-magnesium fluoride 68 ; nickel-carbon+xygen 69 ; strontium oxide-sucrose-water 7O ; sodiumchloride-ammonium hydrogen carbonate-water 71 ; ferric oxide-alumina-calcium oxide 72 ; zinc sulphate-sulphuric acid-water 73 ;50 A.Colani, Compt. rend., 1927, 185, 1475; A., 1928, 131; idem, Bdl. SOC.51 W. Jander, 2. anorg. Chem., 1927,168, 113; A,, 1928, 131.52 E. Janecke, 2. Elektrochem., 1927,33,477 ; A., 1928, 131 ; T. Suzuki andK. Kasai, Sci. Paper.9 Insb. Phys. Chem. Res. Tokyo, 1927, 7, 173 ; A,, 1928, 131.53 J. W. Greig, Amer. J . Sci., 1927, [v], 14, 473; A,, 1928, 132.54 C. H. FranckandH. Heimann, Z.Elektrochem., 1927,33,469; A,, 1928,132.5 5 W. P. Jorissen and G. M. A. Kayser, Rec. trav. chim., 1927, 46, 885; A.,1928, 133.66 C. J. van Nieuwenburg and H. I. Zijlstra, ibid., 1928, 47, 1 ; A,, 228;C. J. van Nieuwenburg and C. N. J. de Nooijer, ibid., p. 625 ; A., 709.5 7 C.Benedicks, 2. physikal. Chemq 1928, 131, 285; A., 242.58 T. Takei, Sci. Rep. Tdhoku Imp. Univ., 1927, 16, 1031; A., 1928, 242.69 (Miss) J. Y. Cann and K. E. Gilmore, J. Physical Chem., 1928, 32, 72;60 M. Matsui and K. Hayashi, J . SOC. Chem. I n d . Japan, 1927, 30, 633;61 W. C. Blasdale and H. L. Robson, J . Amer. Chena. Soc., 1928, 50, 35;62 K. Honda and S. Miura, Sci. Rep. T6hoku Imp. Univ., 1927, 16, 745;63 D. N. Tarassenkov, 2. anorg. Clam., 1928, 169, 407; A., 354.64 F. H. Jeffery, Trans. Paraday SOC., 1928, 24, 209; A., 366.65 F. Frowein, 2. anorg. Chem., 1928, 169, 336; A,, 367.66 Y. Osaka and T. Yaginwha, Bull. Chem. SOC. Japan, 1928,3, 4; A., 367.e7 W. C. Hansen, L. T. Brownmiller, and R. H. Bogue, J . Amer. Chem.6 8 G.Grube (with J. Jaisle), 2. Elektrochern., 1927, 33, 481 ; A., 1928, 376.6o G. Meyer and F. E. C. Scheffer, Rec. truv. chim., 1928,47, 401; A., 480.70 G. Grube and M. Nussbaum, 2. Elektrochem., 1928, 34, 91; A., 480.71 B. Neumann and R. Domke, ibid., p. 136; A., 480.K. Sandved, J., 1927, 2967; A., 1928, 131.chim., 1928, [iv], 43, 194; A., 367.A,, 243.A,, 1928, 243; M. Matsui, ibid., p. 180; A., 1928, 243.A., 243.A,, 1928, 243.Soc., 1928, 50, 396; A., 367.W. C. Hansen and L. T. Brownmiller, Amer. J . Sci., 1928, [v], 15, 226;A,, 480.73 G. Agds and F. Schimmel, Z. angew. Chenz., 1928, 41, 340; A,, 480INOBGCANIU OHEMISTRY. 65cadmium or zinc or magnesium nitrate-nitric acid-water 74 ; sodium-potassium-cadmium-mercury 75 ; tin-lead bromide or chloride ;lead-stannous bromide or chloride ; zinc-cadmium chloride ;cadmium-zinc chloride 76 ; tungsten disulphide-hydrogen 77 ;sodium-tin T8 ; hydrogen chloride-ethyl ether or acetone 79 ;beryllium oxide-silicon dioxide 80 ; magnesium sulphate-sodiumnitrate-water 81 ; carbon monoxide-carbon dioxide-steam-hydro-gen 82 ; copper-tin ; tin-bismuth or cadmium ; sodium nitrate-s odium chloride-sodium sulphate S5 ; carbamide-trichloroacetic acidor other organic materials 86 ; sodium chloride-barium chlorate 87 ;zinc hydroxide-sodium hydroxide 88 ; hydrogen-sodium or othermetals 89; iron-silicon or chromium or phosphorus lithiumperchlorate-water 91 ; alumina-water 92 ; sodium iodate-water g3 ;sodium selenatewater ; magnesium sulphate-water 9* ; magnesium-potassium aluminium chloride ; calcium-sodium aluminium chloride ;aluminium-sodium silicofluoride 95 ; tin-cadmium chloride ; cad-mium-stannous chloride 96 ; silver sulphide-carbon 97 ; cadmium or7 4 G.Malquori, Atti R. Accad. Lincei, 1928, [vi], 7, 146; A., 480.7 5 E. Jlinecke, Z . Metallk., 1928, 20, 113; A., 480.7 6 R. Lorenz and G. Schulz, 2. anorg. Chem., 1928, 170, 247; A,, 694.77 N. Parraveno and G. Malquori, Atti R. Accad. Lincei, 1928, [vi], 7 , 189;78 W. Hume-Rothery, J., 1928, 947; A., 694.79 D. McIntosh, Bull. Chern. SOC. Japan, 1928, 3, 82; A., 594.8o F. Machatschki, Z . physikal. Chem., 1928, 133, 263; A., 594.A., 694.A. Benrsth (with H. Benrath, W. Beu, J. Clerrnont, N. Ilieff, S. Kojitsch,H. PitzIer, and A.Schloemer), 2. anorg. Chem., 1928,170, 267; A., 695.82 B. Neumann and G. Kohler, 2. Elektrochern., 1928, 34, 218; A., 707.83 T. Matsuda, Sci. Rep. Tdhoku Imp. Univ., 1928, 1'7, 141; A., 710.8 p M. Le Blanc, M. Naumann, and D. Tschesno, Ber. Siichs. Ges. Wiss.,85 A. Chretien, Culiche, 1927, 9, 248; A,, 1928, 711.86 N. A. Puschin and D. Konig, Monatsh., 1928, 49, 75; A., 711.88 R. Fricke, 8. anorg. Chem., 1928, 172, 234; A,, 711.math.-phys. Kl., 1927, 79, 71; Chem. Zentr., 1928, i, 401; A., 1928, 710.C. Di Capua and A. Bertoni, Gaxzetta, 1928, 58, 249; A., 711.I. I. Shukov, Ann. Inst. Anal. Physico-Chim. Leningrad, 1927, 3, 600;A., 1928, 841.** C. Kreutzer, 8. Physik, 1928,48, 666; A., 841.*l J. P. Simons and C. D. L. Ropp, J . Amer. Chem. SOC., 1928, 50, 1650;*a G. F. Huttig and E. von Wittgenstein, 2. anopg. Chem., 1928, 171, 323;s3 H. W. Foote and J. E. Vance, Arner. J. Sci., 1928, [v], 16, 68; A,, 842.9p A. Smits (with W. M. Mazee), 2. physikal. Chem., 1928, 135, 62; A.O 6 R. Lorenz and G. Schulz, 2. anorg. Chem., 1928,171, 268; A., 843.*6 R. Lorenz, W. Fraenkel, and P. Wolff, ibid., p. 366; A., 843.*'I N. Parravano and G. Malquori, Atti R . Accad. Lincd, 1928, [Vi], 7,387;REP.-VOL. XXV. 0A., 842.A., 842.Smits (with J. Rinse and L. H. Louwekooymans), ibid., p. 73 ; A,, 843.A., 84466 ~ U A L REPORTS ON THE PROGRESS OF CHEMISTRY.magnanese or silver chloridehydrogen sulphide B8 ; cadmiumbromide-hydrogen sulphide 9B ; sulphur-sulphur monochloride ;potassium chloride-hydrogen chloride-water ; aluminium chloride-hydrogen chloride-water ; aluminium chloride-potassium chloride-water 4; lead nitrate-lithium or cssium nitrate-water ; ceriumsulphate-rubidium sulphate-water ; sodium carbonate-sodiumbicarbonate-water ; chromium trioxide-sulphur trioxide-water ;zinc-carbon dioxide ; cupric sulphate-ammonium oxalate-ammonia lo ; copper-silicon 11 ; antimony-arsenic 12 ; lead, silver,cupric, or nickel chloride-carbon monoxide l3 ; sodium sulphate-lithium iodide l4 ; potassium-ammonium-chloride-nitrate l5 ; cal-cium oxide-magnesium oxide-silica-alumina l6 ; calcium oxide-silicewater 17 ; aluminium-calcium 18 ; cadmium-antimony orlead l9 ; metallic fluorides-hydrogen 2o ; lead-antimony-cadmium 21 ;zinc or magnesium sulphate-sodium sulphate-water ; cobaltsulphate-potassium sulphate-water 22 ; barium carbide-bariumoxide-carbon-carbon monoxide.23H. V. A. BRISCOE.9. L. ROBINSON.B8 K. Jellinek and G. von Podjaski, 2. anorg. Chena., 1928, 171, 261 ; A.,844.K. Jellinek and L. Zucker, &id., p. 271 ; A., 844.D. L. Hammick and M. Zvegintzov, J., 1928, 1785; A,, 956.G. Malquori, Atti R. A c d . Lincei, 1928, [V;], 7, 738; A., 956.a Idem, ibid., p. 740; A., 966.Idem, ibid., p. 745; A., 957.Idem, ibid., p. 495; A., 967.F. Zambonini and S. Restaino, ibid., p. 449; A,, 967.7 R. Wegscheider and J. Mehl, Monat8b., 1928, 49, 283; A,, 967.8 A. W. Rakovski and D. N. Tarassenkov, 2. anorg. Chem., 1928, 174, 91 ;A., 957.K. Jellinek and B. Potiechin, ibid., 173, 164; A., 957.lo M. Herschkovitsch, ibid., p. 222 ; A,, 967.l1 K. Matsuyama, Sci. Rep. Tdhoku Iwq. Univ., 1928, 17, 665; A,, 1094.l* Q. A. Mansuri, J., 1928, 2107; A., 1094.1s L. Belladen end A. Sommariva, Guzzettck, 1928, 58, 443; A,, 1096.14 (Signa.) E. Fabris, Ann. Chim. A p p l . , 1928, 18, 326; A., 1096.1 5 E. Janecke, 2. angew. Chern., 1928, 41, 916; A., 1096.l6 W. C. Hansen, J . Amw. Chem. Soc., 1928, 60, 2165; A,, 1096.1 7 J. R. Baylis, J. P h y k a l Chem., 1928, 32, 1236; A., 1096.18 K. Matsuyama, Sci. Rep. TGhoku Imp. Univ., 1928, 17, 783; A., 1095.1v E. Abel, 0. Redlich, and J. Adler, 2. anorg. Chem., 1928, 174, 257; A.,20 K. Jellinek and A. Rudat, ibicE., 175, 281 ; A., 1191.41 E. Abel, 0. Redlich, and J. Adler, ibid., 174, 269; A., 1191.2% R. M. Caven and W. Johnston, J., 1928, 2606; A., 1191.2s M. de K. Thompson, TTUn8. Amer. Electrochem. SOC., Sept. 1928, Advance1190.copy; A., 1191

ISSN:0365-6217    

DOI:10.1039/AR9282500036

出版商:RSC    

年代:1928

数据来源: RSC

摘要:

ORGANIC CHEMISTRY.PART I.-~PHATIC DIVISION.H ydromrbons.A CONSIDERABLE number of papers dealing with the chemistry ofthe aliphatic hydrocarbons has appeared during the past few yearsand the position now reached would appear to warrant the inclusionof this section in the present Report.Studies of the complex decompositions undergone by simplehydrocarbons under the influence of heat have revealed that insilica vessels, which possess no appreciable catalytic activity, ethanea t 575" yields only ethylene and hydrogen. Further reactionsbetween ethylene and hydrogen then take place, accompanied bythe polymerisation of ethylene and the formation of higher hydro-carbons, propylene, methane, and ethane. It is probable thatsurface action plays a prominent part in bringing about the changes.With propane under the same conditions the following three reactionsappear to take place, (a) and (b) being rapid and (c) slow :At lower temperatures (200--400") in the presence of a nickelcatalyst a different course is followed :The latter reaction becomes prominent only at the higher temper-atures.Under these conditions hydrogen is without effect onthe decomposition but the nature of the catalyst is of greatimportance. 1The rate of dissociation of the simpler hydrocarbons in Pyrexglass tubes a t 650" under 1 atmosphere pressure has been shown todepend on the comparative complexity of the molecule, the mainreactions in the ca8es of ethane, propane, n- and iso-butane being,1 F. E. Frey and D. F. Smith, I d .Eng. Chem., 1928,20, 948; A,, 121168 ANNUAL REPORTS ON THE PROQRESS OF OHEMISTRY.under the prescribed conditions, dehydrogenation and demethan-ation.2When a mixture of hydrogen and ethylene is exposed to ultra-violet light in the presence of mercury vapour, the hydrocarbonsmethane, ethane, propane, and butane are produced. Under similarconditions ethane is unaffected, and the authors consider that theresults can be explained most readily by postulating the intermediateformation of atomic hydrogen, methylene by fission of the ethylene,and ethylene activated by loss of hydrogen.Another example of the complex nature of the rearrangementsobserved during reactions of this type is to be found in the changesundergone by propyl alcohol when it is passed over uranium oxidea t 400".The reaction products include propaldehyde, p-methyl-pentenal and ap-dimethyl-Aab-heptadienal and, by further decom-position of these substances, hydrogen, methane, unsaturatedhydrocarbons, hexane, hexene, and carbon monoxide and dioxide.4The polymerisation of acetylene under the influence of heat hasbeen studied with a variety of catalysts and at different temper-atures. The maximum yield of polymerised product (82%) wasobtained by passing a slow stream of the gas over clay in a glass tubeheated a t 650", and in this case the resulting tar by fractional dis-tillation yielded mainly benzene, naphthalene, and other aromatichydrocarbons. In it metal tube decomposition of the acetylene intocarbon, hydrogen, and other gaseous substances took place morereadily than polymerisation and the composition of the polymerisedmaterial was different, little or no naphthalene being present.5An instance of the usefulness of high-temperature reactions asa means of obtaining acetylenic hydrocarbons is to be found in thedehalogenation of aa-dichloroheptane by passage of its vapour oversoda-lime at 420°, the corresponding acetylene, C,H,,*CiCH, beingobtained in a yield ofAcetylene and carbon dioxide react when heated together in thepresence of metallic catalysts to give saturated hydrocarbons, asmaller amount of unsaturated hydrocarbons, carbon monoxide,and water.Acetylenecarbon monoxide mixtures, with nickel andcobalt as catalysts, give various aldehydes (formaldehyde, acetalde-hyde, acraldehyde) and a mixture of unsaturated hydrocarbons ofhigh molecular weight, along with carbon dioxide and water.'2 R.N. Pease, J . Amer. Chem. SOC., 1928,50, 1779; A., 988.A. R. Olson and C. H. Meyeis, aid., 1927, 49, 3131; A., 1928, 150.A. Mailhe and Renaudie, Compt. rend., 1928,186, 238; A., 268.C. Ssndonnini, Gazzetta, 1927, 57, 781; A., 1928, 43.ti C. Fujio, J . SOC. Chem. I n d . Japan, 1928, 31, 77; A., 732.7 A. J. Hill and F. Tyson, J . Amer. Chem. SOC., 1928, 50, 172 ; A., 269OWAXIC CHEMISTRY.-PART I. 69Amongst other reactions of a similar nature which have beenrecorded there may be mentioned the polymerisation and depoly-merisation of amylenes under the influence of heated silicates? whereagain a complex mixture results containing butylene, heptylene,octylene, nonylene, isopentane, and other products, both saturatedand unsaturated.8The action of the silent electric discharge on ethylenic hydro-carbons appears to be closely similar to that of high temperatureand pressure, prolonged action resulting in the production of highlypolymerised non-volatile substances.The rate of the reaction isgreatly dependent upon the structure of the original hydrocarbonand only slightly on the amount of the electric tension. In the caseof isobutylene polymerisation is accompanied by a redistribution ofhydrogen atoms, and on fractional distillation of the product mainlysaturated hydrocarbons are found in the portions of lower boilingpoint. Fission of the carbon chain and re-arrangement of alkylgroups leading to the formation of hydrocarbons containinghighly branched structures are marked features of the reaction.Naphthenes, but no aromatic substances, are found amongst thefractions of higher boiling point.gAn extensive contribution to the chemistry of the allene hydro-carbons and their derivatives has been made by N.BoU~S,~~who employs the appropriately substituted ally1 alcohol,R*CH(OH)*CK:CH,, as starting point in the preparation of thehydrocarbons. The action of phosphorus tribromide on thesealcohols is accompanied by isomerisation and leads exclusively tothe formation of R*CH:CH*CH2Br.11 Addition of bromine a t 0"now gives the tribromide, R*CHBr*CHBr*CqBr, which when fusedwith 75-80 yo potassium hydroxide yields the allene dibromide,R-CHBrGBr:CH2, from which the allene, R*CH:C:C€€,, is pre-pared by dropwise addition of the dibromide to zinc dust in boilingalcohol. For a detailed description of the various allenes and of thenumerous intermediate products and their derivatives the reader isreferred to the original paper.The addition of bromine (1 mol.)occurs mainly at the &-positions, the apPy-tetrabromo-derivativeresulting from the addition of a second molecule of bromine. Treat-ment of the allene hydrocarbons with concentrated sulphuric acida t -lo", followed by the action of water, gives rise to the ketoneCH,RCO*CH,, and sodamide reacts with the allenes to form sodiumderivatives of the isomeric acetylenes, CH,R*CiCNa.SOC., 1928, 60, 441 ; A., 732.S. V.Lebedev and I. A. Vinogrsdov-Volzynski, J . Russ. Phys. Chern.@ N. D. Prianischnikov, Ber., 1938, 61, [B], 1358; A., 866.lo Ann. Chirn., 1928, [XI, 9, 402; A., 1112.l1 See H. Burton and C. K. Ingold, J., 1928, 904; A., 63470 ANNUAL REPORTS ON THE P~OORESS OF OHEMISTRY.Much attention is being devoted to the properties of hydrocarbonspossessing conjugated double bonds and it is desirable to review insomewhat greater detail certain of the more important paperswhich have appeared in this connexion. Derivatives of py-di-methylbutadiene and of tetramethylbutadiene have been studiedby A. D. Macallum and G. S. Whitby,12 who fmd that the former ofthese substances yields two dibromides, one solid and one liquid.The solid is highly reactive and is shown by ozonolysis to be a1 : 4-dibromo-compound.Some evidence is given in favour of theview that the solid and liquid dibromides possess respectivelytrans- and &configurations. The same authors reach the con-clusion that, in general, butadienes substituted in positions 1 and 4polymerise less readily than the corresponding 2 : 3-derivatives, thusconfirming the views of earlier workers.13Results of great interest are described in a paper dealing withthe bromine addition compounds derivable from butadiene. l4 Ithas long been known that under certain specified conditions theprincipal product which can be isolated is the solid 1 : 4-dibromide l5and it has been generally assumed that the addition gives exclusivelythe 1 : 4-product.It now appears that the isomeric 1 : 2-dibromideis invariably formed during the reaction and that this is an unstablesubstance which undergoes slow spontaneous conversion into the1 : 4-isomeride. It does not follow, however, in view of the ex-perimental evidence now obtained, that the reaction can be ade-quately explained on the basis of 1 : 2-addition, followed by isomeris-ation. Another view would seek to account for the formation of thetwo products by considering that the hydrocarbon is capable ofassuming different polarised forms, C-C-C-C and C-C-C-S. Athird possibility, also suggested in the communication now underreview, is to regard the observed result as incidental to the operationsinvolved in the addition process.According to this idea the firststage of the reaction is of the normal ethylenic type and involves theformation of an addition complex of butadiene and molecularbromine. This is represented by the novel electronic formula (I).Its existence is transient and the subsequent events lead eitherto the formation of the 1 : 2-dibromide (11) (normal course), or tothe 1 : 4-dibromide (111), if the tautomeric properties of thepropene system CBr*C:C += C:C*CBr are brought into play. The+ - +l2 Tram. Roy. SOC. Canada, 1928, [iii], 22, 33, 39; A., 614.lS S. V. Lebedev and B. K. Mereahkovski, J . BUSS. Phy8. Chem. Soa., 1913,l4 E. H. Farmer, C. D. Lawrence, and J. I?. Thorpe, J., 1928, 729; A., 604.l5 G. Griner, C-t. rend., 1893, 116, 723; 117, 663; A., 1893, i, 460;46, 1249; A., 1913, i, 1286.1894, i, 02; J.Thiele, Anmlen, 1899, 808, 333; A,, lQO0, i, 2O R U m C CHEMISTRY .-PART I. 71mechanism involved is illustrated by the accompanying electronicformulae.Br Br*Br Br ..-..H H H H H H H H. . . .(1.) H:C~C:C;C:H --+ H:c:c*~c~"c:H ........ ........Br Br .... Br 4 Br .. ..(11.) H:C:C:CiC:H H:C:CiC:C:H (111.)H H H H H H H HThe additive properties of the conjugated system in hexatrienehave also been studied.16 Two forms of the parent hydrocarbonhave been found to exist, these being represented respectively ascis- and trans-isomerides,C&:CH*EH H$*CH:CH,HC*CH:CH, HC*CH:CH,It has been established that the 3 : 4 glycol (I), which has beenshown to exist in two stereoisomeric forms, gives on brominationboth the 3 : 4- and the 1 : 6-dibromide (11) and that the hexatriene(111) derived from the latter also adds bromine terminally.Migra-tion of bromine would appear to be involved in the 3 : 4-glycol+1 : 6-dibromide transformation, an observation which, if foundto be general, will be of considerable importance in arriving a tviews concerning the reactive forms of conjugated hydrocarbons,yH(OH)*CH:CH2 =- (iH:CH*CH2Br CH*CH:CH, ,,CH( OH)*CH:CH, CH:CH-CqBr CH*CH:CH,........ ........(1.1 (U.1 (111.)When addition of bromine occurs in the absence of hydrogenbromide, both the cis- and the trans-form of hexatriene yield 1 : 2-dibromides. These 1 : 2-&bromides are convertible into the 1 : 6-forms, which are obtained, directly, as mentioned above, by theuse of ordinary commercial bromine containing traces of hydrogenbromide.It is possible, therefore, to consider the chemistry ofhexatriene on the basis of bromine-migration reactions, but theauthors do not rule out altogether the possibility of direct 1 : 6-addition, which could be explained by assuming suitable polarisationof the conjugated molecule in the sense demanded by the modernextension of the Thiele hypothesis.Investigations of the additive properties of butadiene derivativesl6 E. H. Farmer, B. D. Laroia, T. M. Switz, and J. F. Thorpe, J., 1927,2937; A., 1928, 16172 ANNUAL REPORTS ON THE PROGRESS OF OECEMISTRY.have also been carried out by C. Pr6vost,17 who interprets theexperimental results by means of the bromine-migration hypothesis,and considers that the 1 : 4- and 1 : 2- (or 3 : 4)-forms of the semi-saturated derivatives are tautomeric. In the case of butadiene,if the sole primary addition product is the 1 : %compound, thenchanges in experimental conditions affecting the 1 : 2 e 1 : 4isomerisation should have a corresponding effect on the proportionof the two isomerides found in the bromination mixture.Actuallythe rate of isomerisation is found l8 to be little affected by experi-mental conditions and is much too slow to account for the largepercentages of 1 : 4-derivative which are observed. On the otherhand, these percentages are much influenced by the nature of thesolvent employed, and it was for these reasons that the altermtivehypothesis just outlined was put forward by Farmer, Lawrence,and Thorpe.The properties of conjugated systems are being investigated alsoby a study of their behaviour during catalytic hydrogenationin the presence of platinum-black.lg Four types of process aretheoretically possible according to the order in which the conjugateddouble bonds become saturated.The first considered is one whichproceeds in accordance with Thiele’s rule, where primary additionof hydrogen is exclusively in positions 1 and 4, followed by hydro-genation a t a different rate of the ethylenic derivative so produced.Substances such as diisobutenyl, CMe2:CH-CH:CR4e,, in which allthe four hydrogen atoms in the 1 : 4 positions are replaced by aliphaticradicals, belong to this group.The second type is more complexand does not follow Thiele’s rule. The addition of hydrogen takesplace in all the possible directions, 1 : 2 , 3 : 4, and 1 : 4, and is furthercomplicated by the simultaneous formation of fully saturatedmolecules. Isoprene, for example, by the addition of 1 mol. pro-portion of hydrogen yields isopentane (30y0), isopropylethylene(12 yo), as-methylethylethylene (13 yo), trimethylethylene (15%),and unchanged isoprene (30 yo). Divinyl, piperylene, and diiso-propenyl also belong to this type.The simultaneous addition of two molecules of hydrogen, withthe formation of a fully saturated substance, was suggested byC. Paa120 as the normal method of hydrogenation of conjugated1 7 C-t.rend., 1926, 183, 1292; A., 1927, 131; 1927, 184, 1460; A.,1927, 748; 1928, 186, 1209; A., 613; Bull. SOC. chim., 1928, [iv], 43, 996;A., 1212.18 E. H. Farmer, C. D. Lawrence and J. F. Thorpe, Zoc. cit.10 S. V. Lebedev and A. 0. Yakubchik, J., 1928, 823, 2190; J. Buss. Phys.2O Ber., 1912, 45, 2221; A., 1912, i, 703.C M . SOC., 1927: 59, 981; A,, 1928, 613, 1111ORGANIC CHEMISTRY .--PART I. 73compounds. This, however, (Lebedev’s Type 111) has not yet beenobserved experimentally and a further investigation of the ca8esdescribed by Paal reveals that they do not in fact belong to this type.The classification is completed by consideration of a fourth typein which addition of hydrogen occurs exclusively in the 1 : 2- and3 : 4-positionsY no 1 : 4-addition products being formed.Here againthe process does not follow Thiele’s rule. In all cases when onemolecule of hydrogen has been added the number of unchanged(conjugated) molecules is equal to the number of fully saturatedmolecules. A characteristic point during the hydrogenation, andone which determines fully the course of the reaction, is reached whenthe whole of the original conjugated system is consumed. Theauthors term this the “critical point of hydrogenation of a con-jugated system.”In this connexion it is of interest to refer to some hydrogenationexperiments performed with the aid of sodium amalgam.21 Thepreparation of pure amalgam is described and this is found to differwidely in properties from that prepared in the usual way.Forexample, according to von Baeyer, terephthalic acid is reducedexclusively to A2:6-dihydroterephthalic acid, which does notundergo further hydrogenation. Under similar conditions withpure amalgam, A2-tetrahydrophthalic acid is formed, and, contraryboth to the hitherto accepted evidence and to the postulates ofThiele’s theory, the A2-tetrahydrophthalic acid hydrogenates muchmore rapidly than the corresponding A1-acid. The isomerisinginfluence of the alkali hydroxide exerted for very different lengthsof time may possibly help to explain the observed differences.Consideration of the mechanism of these reductions indicatesthat the evolution of nascent hydrogen, which is then added at thedouble bond of the organic molecule, must be regarded as highlyimprobable, and instead of this the addition of sodium a t the doublelinking is postulated, the resulting product being afterwards decom-posed by the water present.22These views may be compared with those advanced by A.Gillet 23in interpreting the hydrogenation of conjugated compounds. Thisauthor regards the process as due to the addition of two sodiumatoms in the 1 : 2-positions followed by isomerisation :>CNa.CIINa*CH:C< + >CINa*CNa:CH*CH<. In a more recentpaper 24 this interpretation is objected to on the ground that itaffords no explanation of the hydrogenation of conjugated com-21 R. Willstiitter, F. Seitz, and E. Bumm, Bep., 1928, 61, [B], 871 ; A,, 766.pa Compare W. Schlenk and E. Bergmann, Annalen, 1928,468, i ; A., 1031 ;this Report, p.96.Bull. SOC. chirn., 1927, [iv], 41, 927; A,, 1927, 921.z4 G. Vavon, ibid., p. 1598; A., 1928, 1SO.0 74 ANNUAL REPORTS ON W E PROGRESS OF OHEMISTRY.pounds by agents, other than sodium, which act by virtue of theproduction of nascent hydrogen.Aldehydes and Ketones.The fact that the p-hydroxypropane- p-sulphonic acid obtainedby hydrolysis of phenyl propane- p p-disulphonate is not identicalwith “ acetone bisulphite ” 25 is at variance with the views of F.Raschig and W. Prahl on the structure of the bisulphite additioncompounds.26 The experiments with phenyl propane- pp-disul-phonate have therefore been repeated by the latter authors, whohave failed to confirm Schroeter’s results and maintain their formu-lation of the bisulphite addition compounds as hydroxy-sulphonicacids, R,C(OH)(S0,H).27 In a vigorous reply by Schroeter newevidence is given in support of his original observations.Since thebisulphite compounds cannot be regarded as sulphurous esters, andSchroeter regards the hydroxy-sulphonic acid structure as disproved,a unitary formulation becomes impossible and the structure(R,C:O)(SO,)(HOH) is now postulated. In this the known labileadditive compound of the aldehyde or ketone with sulphur dioxideis regarded as uniting with water to give a more stable substance,which can behave as a monobasic acid.% On the other hand, thestrong evidence adduced by Raschig and Prahl in favour of thehydroxy-sulphonic acid structure has been supplemented andconfirmed by studies of the Rontgen-ray and absorption spectra ofsuch s~bstances.2~The preparation of aldehydes by Rosenmund’s method has beenfound to proceed more rapidly when freshly precipitated bariumsulphate is used in preparing the palladium catalyst, and theavailability of the method is exemplified in the reduction of stearylchloride.In this case the stearaldehyde produced is accompaniedby a solid dimeride, (C18H360)2, which possesses no aldehydicproperties but yields stearaldehyde on distillation under diminishedpressure. 30A comparison of the reactivities of various alcohols for acetalformation has been made by a study of the rates of reaction ofacetaldehyde with methyl, ethyl, isopropyl, and n-butyl alcohols,25 G.Schroeter, Ber., 1926, 59, [B], 2341; A., 1926, 1226.26 F. Raschig and W. Prahl, Annalen, 1926, 448, 266; A., 1926, 939.27 Idem, Bm., 1928, 61, [B], 179; A., 273.2* G. Schroeter (with M. Sulzbacher), iw., p. 1616; A., 1216.*9 0. Stelling, “ Zusammenhang zwiechen Chemischer Konstitution undK-Rontgen-Absorptions Spektra,” Lund, 1927, p. 168 ; CeUulose Chem.,1928, 9, 100; A., 1217.so R. Feulgen and M. Behrem, 2. phydol. Chem., 1928,177,221; A,, 1117.SeeAnn. Reports, 1927, 24, 66ORUANIC CHEMISTRY .-PA€T I. 75apecially purified materials being used in the presence of a traceof hydrogen chloride. The water eliminated is shown to have amarked effect on the progress of the reaction, the hemi-acetalfirst formed undergoing hydrolysis, with the result that the apparentvalue of the bimolecular coefficient for the reaction between thehemi-acetal and the alcohol diminishes with time.The fouralcohols show only slight differences in behaviour.31 The converseproblem, involving the relation of the structure of ketones to theirreactivity in acetal formation, has also been inve~tigated.~~ In thiscase the extent of acetal formation between ethyl orthoformate andvarious ketones was measured by a specially devised analyticalmethod. Of the following eight ketones-acetone, methyl ethyl,diethyl, methyl n-hexyl, methyl tert.-butyl ketones, acetophenone,propiophenone, and benzophenone-acetone showed most reactivity(00% acetal formation) and methyl tert.-butyl ketone least (12%).In general, substitution of higher n-alkyl radicals for the methylgroup in acetone redrices the reactivity slightly, greater reductionsbeing observed with the aromatic ketones.Compounds possessing the general skeleton (I) or (11), where Xis an electro-negative group, are usually tautomeric , the mobilityand point of equilibrium being the resultant of structural factors.I I > C=C-CHX (11.1 1 1 (1.1 >CH--C=CXInvestigations into the properties of such systems have now beenextended to include cyclohexylideneacetone and cyclohexylidene-methyl ethyl ketone.= Each of these substances reacts in two forms,(111) and (IV), both of which have been isolated.These showcharacteristic differences in physical and chemical properties, andunder the influence of catalysts each form undergoes partial con-version into the other, the equilibrium mixture containing about70% of (IV).It was found that the freshly formed cyclohexylidene-acetone is much more labile than the purified material and it issuggested that the greatly enhanced reactivity is to be attributedto the changed properties of substances in statu nascendi.a Theproof thus supplied of the existence of pairs of substances which81 H. Adkins and A. E. Broderick, J . Amer. C h . SOC., 1928, 50, 178; A.,s2 H. E. Carswell and H. Adkins, ibid., p. 236 ; A., 274.58 A. H. Dickins, W. E. Hugh, and G. A. R. Kon, J., 1928, 1630; A., 887.84 Compare F. R. Goss and C. K. Ingold, J., 1926,127,2776; A., 1926, 289.27476 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.form an equilibrium mixture under the influence of catalystsemphasises the analogy existing between tautomeric substances ofthe keto-enol class and those containing the " three-carbon system."Further evidence in this connexion is being obtained from a studyof the condensation of ketones with ethyl acetoacet'ate to givetautomeric substances of such a type asA more complicated system containing the three-carbon skeletonis found amongst the substances obtained by the catalytic inter-molecular condensation of methyl ethyl ketone.The four productstheoretically probable may be divided into two pairs (I) and (11),(111) and (IV), each pair consisting of substances which should(1.1 CH,Me*CMe:CH*COEt CHMe:CMe*CH,*COEt. (11.)(111.1 CH,Me*CMe:CMe- COMe CHMe:CMeCHMe*COMe.(IV. 1exhibit tautomerism of the type now under consideration. As theresult of recent work in this difficult field all the above four sub-stances have been synthesised and the relationships existing betweenthe various homomesitones have been succehsfully established.36It appears that alkaline condensing agents acting .on methyl ethylketone lead to mixtures of (I) and (11) containing the former inexcess. Acid condensing agents, on the other hand, give ketoneswith a branched chain, (111) and (IV), sulphuric acid giving mainly(IV) and hydrochloric acid (111). Definite indications have beenobtained that the homomesitones display cis-trans isomerism ;for example, (IV) gives two different semicarbazones, m. p.203-204" and 163". It has also been proved that the homomesitonesexhibit tautomerism of the expected kind. For instance, (I) or (11)under the influence of catalysts yields an equilibrium mixture whichcontains some 68% of the a@-compound. In this case the mobilityis high, but with (111) and (IV) a very low mobility is encounteredand the final equilibrium mixture contains only 17% of the a@-com-pound. The difference between the two pairs of ketones is probablyattributable to the effect produced by the a-methyl group in (111)and (IV), which has already been found to favour the @y-phase incertain cases.3'The catalytic condensation of methyl ethyl ketone has been35 L. G. Jupp, G. A. R. Kon, and E. H. Lockton, J., 1928, 1638; A., 885.313 (Miss) A.E. Abbott, G. A. R. Kon, and R. D. Satchell, ibid., p. 2514; A.,See G. A. R. Kon and B. T. Narayanan, J., 1927, 1836; A., 1927, 873;1218.A. A Goldberg and R. P. Linstead, J., 1928, 2343; A., 1214OBGLWIC CHEMISTRY.-PART I. 77examined also by A. Petrov,w who finds that, at the ordinary temper-ature and under the duence of agents such as hydrogen chloride,sulphuric acid and sodium ethoxide, products analogous to thosederivable from acetone are obtained, but that the yield of triethylbenz-ene is remarkably small. At about 400"/100 atm., in the presence ofaluminium oxide, the total yield of hydrocarbons from methyl ethylketone is very low (8%), homomesitylene oxide and homoiso-phorone being obtained. The action of sodamide at 0" results in theformation of a mixture containing the four possible homoisophorones,C,,H,O, but the isomerides (A) and (B) seem to predominate :Acids.Differences of opinion continue to exist concerning the mechanismof Kolbe's electro-synthesis of hydrocarbons.The view of Schall,sthat acid peroxides are the intermediate products formed at theanode during the electrolysis of fatty acids, has been stronglysupported by the work of F. Fichter,m who extends the peroxidetheory to electro-chemical oxidation in general. Direct evidencein support of the peroxide theory is claimed as the result of experi-ments with potassium hexoate, which, when electrolysed at lowtemperatures, was found to yield small quantities of the acidperoxide. From a comparison of the course of decomposition ofthe peroxide and the per-acid with the behaviour of the acid duringelectrolysis it appeared that the latter reaction proceeded via theperoxide.On the other hand, 0.J. Walker 41 has obtained evidence whichis regarded as incompatible with the peroxide theory. This authorholds that the detection of peroxides during electrolysis furnishesno proof that the Kolbe reaction itself proceeds through theseintermediate compounds, and comments are made on the greatdifficulties encountered in isolating from the electro-chemicalproducts any peroxide, even at temperatures where the peroxide isknown to be stable. E'urthermore, a study of the thermal decom-position of acetyl peroxide, in the pure state or in solution, showsthat only small amounts of ethane are produced, although com-paratively large quantities of methane are formed.Since methaneis never found amongst %he anode gases during the electrolysis of8s Ber., 1927, 60, [B], 2548; A., 1928, 166.89 2. Elektrochem., 1896, 3, 83; A., 1897, i, 317.4* Tram. Amer. EZectrochern. Soc., 1924, 45, 131; A., 1924, i, 829; J .Chim. ph@que, 1926, 23, 481 ; A., 1926,912; F. Fichter and R. Zumbrunn,Hetv. Chim. Acta, 1927, 10, 869; A,, 1928, 45.41 J., 1928, 2040; A,, 111478 ANNUAL REPORTS ON THE PROGRESS OF UHEMISTRY.acetates, whereas ethane is still formed a t temperatures (100') farabove the decomposition point of acetyl peroxide, the availableexperimental evidence is held to be decidedly against the peroxidetheory.Treatment of a solution of oxalic acid a t 60" with a deficiencyof potassium permanganate in an inert atmosphere results in theformation of an activated variety of oxalic acid, which in nearlyneutral solution is capable of reducing chromic acid, bromine,bromate, and nitrate, as well as salts of silver, platinum, andmercury. The activated form was not isolated and yielded quan-titatively the ordinary calcium oxalate.The activated acid regainedits normal properties slowly at the ordinary temperature and morerapidly when heated.42A study of the action of thionyl chloride on organic acids revealssurprising differences from acid to acid. For example, oxalic,tartaric, and fumaric acids are unattacked, chloroacetic acid (butnot trichloroacetic acid or glycine), malonic, suberic, and sebacicacids form acid chlorides, and succinic, glutaric, and maleic acidsyield anhydrides.In the aromatic series, acid chloride formationis more general, but here again certain acids (e.g., terephthalic andp-hydroxybenzoic) remain unaffected and others (phthalic acid) givethe anhydride.43It has been found that the action of acetic anhydride on simplemonocarboxylic acids yields only the simple acid anhydride and nota mixed anhydride as is generally supposed. The simple anhydrideoften crystallises with one molecule of acetic anhydride of crystal-lisation, giving a substance whose empirical formula is identicalwith that of the mixed anhydride.44The action of bromine water on olefinic acids has been investigatedfrom the point of view of the effect of the concentration of the acid.45By maleic acid in 0-05N-aqueous solution 89.3% of the reactingbromine was converted into the bromohydrin, and this proportionfell to 62.5y0 in a 0-33N-solution.Maleic acid therefore behavessimilarly to ethylene and ally1 alcohol.** Sodium maleate reacts42 F. Oberhauser and W. Hensinger, Ber., 1928, 61, [B], 621; A., 605;A. E. Tschitschibabin, J. pr. Chem., 1928, 120, 214; A., 1929, 48.43 L. McMaster and F. F. Ahman, J . Amer. Chem. SOC., 1928,50, 146; A,,271.44 A. W. Van der Haar, Rec. trav. chim., 1928, 47,321 ; A,, 393. ContrastW. Autenrieth, Ber., 1887, 20, 3187; A., 1888, 260, and P. Askenmy andV. Meyer, Ber., 1893, 26, 1364; A., 1893, 607.45 J. Read and W.G. Reid, J., 1928, 746; A., 606. Compare E. Biilmann,Rec. trav. chim., 1917, 36, 313; A., 1917, i, 378.4* J. Read and R. G. Hook, J., 1920, 117, 1214; J. Read end E. Hurst,J., 1922, 121, 989OWANIC CHEMISTRY .-PUT I. 79much more rapidly than the free acid with increase in the proportionof bromohydrin (95.6% at 0.05N: 7506% at 0.33N). Undersimilar conditions, fumaric acid reacted with extreme slowness, andthe sodium salt gave, with a velocity about half that of the maleate,a slightly enhanced proportion of bromohydrin. With oleic acid(O.lh'-mixture), only some 51% of the bromine was found to beeffective. Although it was formerly considered essential to carryout experiments of this type a t a low temperature and in theabsence of bright light, it is now known that in certain cases lightpromotes the reaction; and it is shown that with oleic acid, raisingthe temperature to 90" results in increased yields of the bromo-hydrin.A comparison of the behaviour of acid anhydrides and of acidswhen passed over heated thoria, shows that the former are convertedmore easily into the corresponding ketones ; and it is suggested that,in 'the synthesis from acids, ketones arise rather from the inter-mediate formation and decomposition of the anhydrides thanthrough the thorium salts.Experiments on the formation of aceticanhydride from acetic acid by passage over titanic oxide at 300"are described in support of this ~ i e w . 4 ~The catalytic decomposition of suberic acid under the influenceof heat is found to proceed most satisfactorily in the presence of anequal weight of iron filings along with 5% by weight of crystallisedbaryta.Inthis case also, the mechanism of reaction which is considered mostprobable involves the intermediate formation of the acid anhydride.48A continuation of researches on the action of heat on salts ofpolymethylenedicarboxylic acids, the earlier stages of which havealready received mention in these Reports,49 has now led to theformation of rings containing as many as twenty-two carbon atoms.For instance, the action of heat on the yttrium salt of nonane-1 : 9-dicarboxylic acid furnishes some cycloeicosane- 1 : 11 -dione, which,when reduced by Clemmensen's method, yields cycloeicosanone.The same cyclic ketone is obtained from the thorium salt of japanicacid (from Japan wax), the constitution of which is now proved to benonadecane-1 : 19-dicarboxylic acid.A reaction similar to thatgiven by the nonane homologue leads to the form'ation from yttriumdecane- 1 : 10-dicarboxylate of a small quantity of cyclodocosane-1 : 12-dione, containing a ring of 22 carbon atoms. Only slighttraces of cyclic ketones are reported from the action of heat on thethorium or yttrium salts of tetradecane-1 : 13- or -2 : 13-dicarboxylicacid , Z-methyldodecane- 1 : 12-dicarboxylic acid, and other pents-Yields up to 40% of suberone are thus obtainable.4 7 J. Campardou and M. %on, Compt. rend., 1928,186, 691 ; A., 393.I s I. Vogel, J., 1928, 2032; A., 1136. 4e Ann. Reports, 1926, 23, 11280 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.decane-, hexadecane-, and tetradecane-dicarboxylic acids, whichsometimes give aliphatic ketones in small amount.For instance,from 2 : 13-dimethyltetradecane-1 : 14-dicarboxylic acid, smallquantities of methyl 2 : 13-dimethyltetradecyl ketone were obtained,and similar aliphatic ketones have been observed as accompanyingthe cyclic ketones in cases where these are f0rmed.mSeveral communications by R. Adams and his collaborators dealwith acids synthesised in the course of their search for substancestoxic towards B. l e p m . The number of new individual substancesobtained is so large that little more can be done than to indicate thenature of the various series investigated. These include cyclo-hexylalkylacetic acids, cyclohexylmethyl-alkylacetic acids, cyclo-pentylalkylacetic acids, (1-cyclopentylethyl-ethylalkylacetic acids,corresponding p - A2 - c y clopent enyl acids, c yclopr o p ylme t hyl- alk y 1 -acetic acids, and di(cycZohexylalky1)-acetic acids.In general itmay be said that in all series maximum toxicity towards B. lepmis shown by acids containing 16-18 carbon atoms. Bactericidalpower appears to depend little on the position of the carboxyl groupin the hydrocarbon chain, and again cycloalkylalkylacetic acids ofequal molecular weight or with equally long side chains differ onlyslightly in toxicity whether the cycloalkyl group is cyclohexyl, cyclo-pentyl, cyclopentenyl, or cyclopropyl. In the last series mentionedabove, no increased toxicity was developed by the introductionof a second cyclohexyl group, giving compounds of the typeC6H11*[CH2]z*CH(C02H)*[CH2],*C,H,,, despite the fact that thepresence of one such group at the end of certain straight-chainaliphatic acids induces toxicity towards the bacillus.51 The interestat present evoked by acids of this type is further shown by a longpaper on the reactions involved in the degradation of chaulmoogricacid, 12-A2-cyclopentenyldodecane- 1 -carboxylic acid, a synthesisof which was mentioned in last year’s Report (p.88), to homo-hydnocarpylamine, C6H,-[CH2]11*NH2, a modified form of Curtiusreaction being employed.52That the substance C8HI2O4 obtained by oxidation of a-A3-carenecannot be either a- or p-isopropylglutaconic acid has been shown inthe following way : 53 The synthesis of a-isopropylglutaconic acid10 L.Rmicka, M. Stoll, H. Schinz, Helv. Chim. Acta, 1928, 11, 670; A.,887; L. Ruzicka, H. Schinz, and M. Pfeiffer, ibid., p. 686; A,, 887,51 R. Adams, W. M. Stanley, and H. A. Stearns, J . Arner. Chem. SOC.,1928,50, 1475; A,, 764; G. R. Yohe and R. Adams, ibid., p. 1503; A., 754;J. A. Arvin and R. Adams, ibid., pp. 1790, 1983; A., 1003, 1003; L. A.Davies and R. Adams, ibid., p. 2297; A., 1132.O* C. Naegeliand G. Stefanovitsch, Helv. Chim. Acta, 1928,11,609; A., 881.68 K. V. Harihsran, IC. N. Menon, and J. L. Simonsen, J., 1928, 431; A.,396ORGANIC CHEMISTRY .-PART I. 81has been achieved by removing hydrogen chloride from ethyl B-chloro-a-isopropylglutarate (A), the preparation of the latter sub-stance being effected by the following series of reactions :CO,Et*CHPrWO*CH,*CO,Et --+ CO,Et*CHPrs*CH( OH)*CH,*CO,Et--+ C02Et*CHPrfl*CHC1*CH,*C02Et (A)The resulting a-isopropylglutaconic acid was separated into cis-and trans-forms by means of acetyl chloride.The correspondingp-isopropyl acid has also been prepared, but neither of these acidswas identical with t’he above substance C8HI2O4, for which the cyclicstructure /’ has been tentatively advanced.54yMe,;CH*C 0,HCH-CH,*CO,HThe difficult problem of the constitution of Balbiano’s acidhas been resolved by a synthesis which serves to establish itsstructure.55 This dibasic acid, C,H,,O,, was obtained by Balbiano 543in the course of oxidation experiments carried out with cam-phoric acid.When reduced it gives a monobasic lactonic acid,C,H,,04, which, on further reduction, yields app-trimethylglutaricacid. Of the possible alternative formulze (I) and (11) for thelactonic acid, the second is ruled out by synthesis,57 and (I) isCHMe-CO CH,-COtherefore Balbiano’s lactoiiic acid. The structure of the parentacid could not, however, be settled by this observation, and formany years the rival formulz of Balbiano (111) and of Mahla andTiemann (IV) 58 held the field. In more recent years the latter wasmodified by Kon, Stevenson, and T h ~ r p e , ~ ~ who preferred torepresent the acid in the liquid state or in solution, as an equili-brium mixture of the tautomeric forms (IV) and (V).It wasapparent by this time that Balbiano’s oxide structure of the acidcould not satisfy the experimental requirements, and syntheticproof of the keto-structure has now been supplied.(111.) (IV.1 (V.1s4 J. L. Simonsen and M. G. Rau, J., 1923,123, 553.5s J. C. Bsrdhan, J., 1928, 2591, 2604; A., 1243, 1215.56 Rend. R. Accad. Lincei, 1892, i, 278; A., 1893, i, 174.5 7 G. Blanc, BuEE. SOC. chim., 1901, 25, 68; A., 1901, i, 119.s* Ber., 1895, 28, 2161; A., 1896, i, 678.6s J . , 1922, 121, 65682 ANNUAL REPORTS ON THE PROURESS OF CHEMISTRY.The synthesis of ccpp-trisubstituted ketoglutaric acids such as (IV)is a matter of considerable difficulty, success being achieved in thepresent case by oxidising the acetyl group of app-trimethyl-laevulicacid (VI) to the CO-CO,H group.This necessitated a synthesis ofapp-trimethyl-laevulic acid, which was prepared, along with itsisomeride (VII), from the acid chloride (VIII) by the action ofFMe,*CO-CH, QRle2*C02H FMe,*COClCHMe *CO,H CHMe*CO *CH, CHNe*CO,Et(VI. 1 (VII.) (VIII.)zinc methyl iodide. The acid chloride was obtained from the halfester COzH~CMe,~CHMe*COzEt prepared by the action of sodiumethoxide on trimethylsuccinic anhydride. Since the last reaction mayresult in the formation to some extent of CO,Et*CMe,*CHMe*CO,H,the presence of isomerides is readily explicable. Separation of theapp- and the a@-trimethyl-lmwlic acids was accomplished byfractional crystallisation of the semicarbazones and complete proofof their identity was furnished by an independent synthesis of theaaP-compomd.Balbiano's acid was readily obtained by oxidation of app-trimethyl-laevulic acid, and since the synthesis just described is consistent onlywith the keto-formula the solid acid most probably exists in thisform.The proof now given of the structure of the acid serves inno way to diminish the remarkable nature of the changes by whichit is formed from camphoric acid, and the author now advances thefollowing scheme as providing the simplest explanation of thetransformation.a+5lO*CO2H p 2 Hp 2 H p e z -++ F02H 9Me2CH,-CMe*CO,H CH,-CMe*CO,HThe number of papers which have appeared during the year bearsample testimony to the continued interest taken in the natural'O J.C. Bardhan, Zoc. cit. compare J. Bredt, Ber., 1893, 26, 3060; A.,1894, i, 141ORGAN10 CHEmTRY.-FAR'X: I. 83fats and the acids derived from them. Studies of the decompositionof oleic acid in the presence of 30% of aluminium chloride showthat the reaction, which begins at the ordinary temperature, becomesvery vigorous at 150" and results in the formation of carbon dioxide,idammable unsaturated gases, and liquid products. Hydrocarbonsof the paraffin and eyeloparaifin types are formed, but neither hydro-aromatic derivatives nor solid p a r a f f i could be obtained. Thereaction proceeds even more readily with palmitic and steasic acids,yielding unsaturated gases, a small liquid distillate, and considerablequantities of a solid p a r a w c hydrocarbon, It is suggested that thelatter two acids may be the parent substances of petroleums richin solid paraffins.61As a result of a quantitative study62 of the oxidation of methyloleate and methyl elaidate by means of hydrogen peroxide in thepresence of acetic acid, it is again suggested that under these con-ditions oleates yield the dihydroxystearic acid of m.p. 95" andelaidates give the isomeride, m. p. 132", neither reaction involvingany change in the molecular configuration. This conclusion is inconflict with the general views of Lapworth and Mottram 63 and ofBoeseken and Belk~fante,~Q who consider that the oxidation withpermanganate, which produces the acid of 111. p. 132" from oIeicacid, does not involve cor@uratioml transformation.It i~ pointedout that the experimental conditions of the permanganate oxidationnecessitate in this particular cam the use of a large excess of alkali,which, in the opinion of Hilditch, may promote komeric change.On the other hand, it must be urged that experimental evidence insupport of the opposite view has been contrib~ted.~5 It is shownthat, in a series of alicycIic compounds containing an ethyleniclinking, permanganate gives invariably cis-glycols whereas per-acids give xhe to trans-isomerides.The pyrogenic decomposition of methyl ricinoleate has beeninvestigated in order to determine the position of the double bond,and its behaviour under the influence of heat, the ester being usedowing to the tendency of the free acid to polymerise.Heptrtlde-hyde and methyl undecenoate were obtained in good yieId by choiceof suitable conditions of heating and no sign of either racemisationor migration of the double bond could be detected.86An mid of common occurrence in marine animal oils is namedN. D. Zelinski and K. P. Lavrovski, Ber., 1928,61, [B], 1064; A,, 731.6* T. P. Hilditch and C. H. Lea, J., 1928, 1678; A., 868,68 M m . Mancheater La. Phil. SOL, 1927, 71, 63; A., 1928, 221,61 Rec. trav. chim., 1926, 45, 917; A., 1927, 132.65 See J. Bikeken, ibid., 1928, 47, 683; A., 734.66 P. S. Psniutin, J . Buss. Phy8. Chem. Soc., 1928, 80, 1 ; A,, 61784 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.cetoleic acid, C,,H&O,. It is isomeric with erucic acid and althoughthe latter has been frequently recorded as occurring in marineanimal oils, its presence is now considered doubtful.The sug-gestion is made that the supposed erucic acid was in reality cetoleicacid which, when oxidised by potassium permanganate in acetone,yields n-undecoic acid and nonane-l : 9-dicarboxylic acid. Aftertreatment with ozone the same two acids and also n-undecaldehydewere identsed, the constitution of cetoleic acid being thus provedto be CR,*[CH,],*CH:CH*[CH,],*CO,H. The same author 67 hasinvestigated the structure of zoomaric acid, a hexadecenoic acidfound in cod-liver oil, and various whale oils. This proves to beCH,*[CH,],*CH:CH*[CH,],*CO,H, identical with an acid namedpalmitoleic and isolated from a specimen of South Georgia whale oil.68Amongst other acids, obtainable from natural source8, whosestructures have now been elucidated may be mentioned jalapinolicacid, which has been shown to be d-10-hydroxyhexadecoic acid.In the course of the work various hydroxy- and keto-fatty acids wereprepared and both 11-hydroxypentadecoic and 1 l-hydroxyhexa-decoic acids were synthesised, The former of these differs struc-turally from convolvulinolic acid, which occurs along with jala-pinolic acid in the jalapin gluco~ides.~~The use of triphenylmethyl ethers, which have proved so advan-tageous in synthetic work in the carbohydrate group, has now beenextended to the synthesis of partly acylated glycerides.Thepreparation of glycerol ap-dibenzoate may be cited as an exampleof the method. Glycerol or-monotriphenylmethyl ether is firstprepared and the dibenzoate of this substance when treated withhydrobromic acid in acetic acid at 0" readily yields glycerol orp-di-benzoate.By suitable modifications of the process glycerol p-benz-oate, glycerol p-p-nitrobenzoate, and other similar compounds maybe prepared.,OIt is only within recent years that methods have become availablefor determining quantitatively the composition of natural fats, andfigures are available for only a few of the fats in common use.Information concerning the way in which the fatty acids are com-bined with glycerol in the fats is still more lacking owing to the veryconsiderable experimental di%culties which have to be faced. In arecent paper71 results are given which have been obtained by the6 7 Y.Toyama, J . SOC. Chem. Ind. Japan, 1927,30, 597, 603; A., 1928,164.68 E. F. Armstrong and T. P. Hilditch, J . SOC. Chem. Ind., 1925, 44, 1801.;6B L.A. DaviesandR. Adams, J. Amer. Chem. Xoc., 1928,50,1749; A., 990.' 0 B. Helferich, P. E. Speidel, and W. Toeldte, Ber., 1923, 56, 766; A.,1923, i, 331 ; B. Helferich and H. Sieber, 2. physiol. Chem., 1927, 170, 31 ;1928, 175, 311; A., 44, 734.A., 1925, i, 778.'l T. P. Hilditch and C. H. Lea, J., 1927, 3106; A., 1928, 162ORGANIC CHEMISTRY.-PART I. 85application of new principles in an attempt to elucidate this complexproblem. The underlying idea has been to alter the chemicalcharacteristics of the glycerides in such a manner that new glycerides,more readily separable, may be obtained without disturbance of thecombined glyceryl radical.Two such processes are described :(a) controlled oxidation by potassium permanganate in acetone,which does not affect saturated glycerides, but converts the mono-,di-, and tri-oleins into the corresponding acid azelaic esters; (b)controlled oxidation with an acetic acid solution of hydrogenperoxide, which is again without effect on the saturated glyceridesbut gives dihydroxystearic esters with oleins. In so far as theresults obtained can be summarised in the space now available, itappears, contrary to a widespread impression, that in vegetableglycerides the fatty acids are distributed impartially rather thanselectively and that in consequence the occurrence of simple tri-glycerides and mixed saturated glycerides is reduced to a minimum.Thus the physical properties of such a fat must depend primarilyupon the particular mixture of fatty acids from which it takes itsorigin.For instance, Cacao butter, which contains palmitic,stearic, and oleic acids in approximately equal proportions, consistsmainly of mono-oleic disaturated glycerides and this fat more,closely resembles an individual glyceride than one in which theproportions of the component acids are very different. Again, incotton-seed oil entirely saturated glycerides are present only in verysmall proportion, and the palmitic acid is uniformly combined withthe unsaturated acids, the proportion of palmitic and unsaturatedacids being approximately 1 to 3.In mutbon tallow, taken as arepresentative of the animal fats, a very different state of affairsprevails and a much greater proportion of fully saturabed glyceridesis present.Another method which is being employed with success in thestudy of natural glycerides consists in the bromination of the fatin light petroleum, followed by separation of the bromides bydissolution in various solvents. The constitution of the individualbrominated glycerides may then be determined by means ofhydrolysis with hydrochloric acid. Linseed oil has in this wayyielded dilinoleolinolenin bromide, two linoleodilinolein bromidesand dilinoleo-olein bromide. Soya-bean oil, train oil, oil of silk-worm pupa, and cod-liver oil have also been investigated and thelarge number of individual glycerides separated and identified bySuzuki and his collaborators provides a tribute both to the skill ofthe workers and to the power of the experimental method.7272 B.Suzuki and Y. Yokoyama, PTOC. Imp. Acad. Tokyo, 1927,3, 526,529;1928, 4, 161; A., 152, 736; B. Suzuki and Y. Masuda, ibid., 1927, 3, 531;1928, 4, 161, 165; A., 153, 736. See also (for soya-bean oil) K. Hashi, J .SOC. Chem. Ind. Japan? 1927,30, 849, 866; A., 1928, 73686 ANNUAL REPORTS ON THE PROGRESS OF OHEMISTRY.NitTqen CO?T&'pCYUnds.Important developments have taken place during the year inthe chemistry of the aliphatic diazo-compounds. It has beenknown for some time that certain aldehydes react with diazomethaneto form methyl ketones,73R*CHO + CH,N, + R-CO-CH, + N,,and an analogous reaction was later applied to certain acid chloridesand expressed as follows : 74R-COCL + CH,N2 + R*CO*CH,Cl + N2.This observation has now been followed by detailed investigationswhich have revealed'5 that the course of the reaction with acylchlorides is in point of fact very different from that indicated in theabove equation, and that the primary product is a diazo-ketone.The chloro-ketone, if formed at all, is the result of subsequentdecomposition of the diazo-ketone in the presence of halogen acid.The general nature of the reaction for the acylation of diazomethanehas thus been established and may be summarised by equations(A), (B), and (C), of which under all conditions (A) and (B) pre-dominate over the secondary reaction (C) :R*COCl+ CH,N, --+ R-CO-CHN, + HCI .. (A)R*CO*CHN2 + HC1+ R*CO*CH,Cl + N, . . (C)CH2N2+HCl+ CH3Cl+N, . . . . (B)The best conditions foI: the preparation of the diazo-ketones involvethe addition of the acid chloride (1 mol.) to an ethereal solution ofdiazomethane (2 mols.), and Nierenstein 7f3 has recently claimed thatby adding the reagents in the reverse order the course of the re-action may be altered with the production of the chloro-ketone inhigh yields. Other workers,?' however, have failed to co&m thisview and maintain that under all conditions (A) is the primaryreaction. If a chloro-ketone is required, the best procedure is tomake the diazo-ketone and submit it to the action of hydrogenchloride.73 H.Meyer, Monateh., 1906,26, 1300; A., 1906, i, 87.74 D. A. Clibbena and M. Nierenstein, J., 1916,107, 1491 ; A., 1916, i, 1062.See also R. T. Dale and M. Nierenatein, Ber., 1927, 60, [BJ, 1026; A,, 1927,664.7 6 W. Bradley and R. Robinson, J., 1928, 1310, 1646; A., 769; F. Arndtand J. Amende, Ber., 1928, 61, [B], 1122; A.* 769. Compare F. Arndt,B. Eistert, and J. Partale, Ber., 1927, 60, [B], 1364; A,, 1927, 774.70 Nature, 1928, 121, 940; A., 739.77 W. Bradley and G. Schwarzenbach, J., 1928, 2904; A., 1929, 68ORGAN10 UHEWSTRY .-PART I. 87Since the diazenes R,*CN2 react vigorously both with electronseeking agents such as halogen molecules and w&h electron-donatingagents (for instance, organo-metallic compounds), theee compoundspresent interesting problems from the point of view of the electrontheory of ~alency,~8 on which basis the Angeli-Thiele formula maybe written CR,=&=N=, where a line represents two electrons.Different positions in the diazomethane molecule are involved inthe two types of reactions referred to and it is found that the anionoidcentre is situated on the carbon atom next to the positively chargednitrogen atom, and the negatively charged nitrogen is the kationoidcentre.The apparent anomaly is explained by assuming that themaintenance of atomic electron configurations is more importantthan neutralkation of the charges and it is shown that in each casethe ultimate result of the electronic displacements postulated in theanionoid (A) and in the kationoid type of reactivity (B) is a moreeven distribution of the charge :0 l o - (A) CH2=N=N= CH2-N-N=-&/The reaction with magnesium phenyl bromide may beas an example of kationoid reactivity,(B)considered+ - ++ - ICR2=N=N- + Fh{Mg}Br --+ CR,=N-&PhYMg Br ++I -bht the action of acids on diazomethane is probably representedby the scheme (A).+X-@ + CH2=h=k + ~(H--CH,--N=_N-- -+P - +X CH3 + -"- + XCH, + N,In this case the process depends upon the intermediate formationof a diazonium salt, which then decomposes in the usual way.Rather more complex cases are to be found in the reactions betweenthe diazenes and aldehydes and acyl chlorides.A possible mechanism for the former is given in the annexedequations, although it is necessary to remember that the f;rst stagemay proceed only to a minute extent, instead of involving the com-plete transfer of charge here represented.Once the carbon atomaare joined, the main changes leading to the separation of nitrogen' 8 W. Bradley and R. Robinson, loc. cit88 ANNUAL REPORTS ON THE PBOGRESS OF CHEMISTRY.and the wandering of a proton may proceed by the more direct routeindicated in the expression (B) I 1-0-) - +- ff - I R*CH=O< + Cq=NzN= --+ RCH-CH2-N5-As an example of the latter type of reaction the formation of diazo-acetophenone from benzoyl chloride and diazomethane may berepresented by the following two stages, the explanation given beingquoted from the paper by Bradley and Robinson.0 tf - A-!! I I Ph-Q--CH='N-N- P h y - - - < i H N ,C1 H Cl @" At this stage the terminal nitrogen has succeeded in transferringa fraction of its negative charge to the oxygen atom and a bondbetween the carbon atoms has been initiated. The repulsionexerted by the central nitrogen on the proton indicated is nowreinforced by the oxygen and chlorine nuclei and the followingchanges may be almost synchronous."This conception of a reaction mechanism, in which the direction isinitiated and controlled by a process involving fractional valenciesbut the course is completed by a different and more direct route,was put forward in explanation of m-substitution in the benzeneseries some years ag0,79 and is now shown to be of wide generalapplication.79 R, Robinson, M m .Xa&ter P?d. SOC., 1920, 64, No. 4; A., 1921,ii, 646ORQANIC CHEMISTRY .-PART I. 89As the result of studies on the action of diazomethane on aldehydesit is concluded 80 that the course of the reaction is governed principallyby the nature of the aldehyde and t o a lesser extent by experimentalconditions. Amongst the examples quoted in support of this viewthe following may be mentioned as illustrative. Although m-nitro-benzaldehyde affords exclusively m-nitroacetophenone, the p -isomeride gives a mixture of p-nitroacetophenone and p-nitro-phenylethylene oxide. Chloral is converted into aaa-trichloro-propylene &-oxide, and the earlier claim 81 that trichloroacetoneis obtainable in this reaction is not substantiated.The availableevidence appears to indicate that substituted ethylene oxides areformed most readily from those aldehydes which show a pro-nounced tendency towards the formation of hydrates.The behaviour of diazomethane has been examined from yetanother point of view by H. Meerwein and W. Burneleit.82 Theseauthors have investigated the possibility of activating atomicgroups, in this case the carbonyl group, by means of complexformation. At low temperatures a solution of diazomethane inacetone undergoes little or no change, but on addition of some10% of water nitrogen is freely evolved, and the reaction thusinitiated continues as diazomethane is added, until about 80% of theequivalent amount has been used. The products include as-dimethylethylene oxide, methyl ethyl ketone, and in all probabilitydiethyl ketone and methyl n-propyl ketone.The authors representthe course of the change by the accompanying equations, theactivity of the diazomethane being anionoid in character and pro-ceeding in accordance with the scheme outlined above.Further reaction with diazomethane yields methyl ethyl ketoneand then higher ketones. During the reaction the added waterremains unmethylated and in a similar way alcohols, which mayreplace the water as catalysts, remain unaffected. Since dilutesodium hydroxide solution also promotes the reaction, the activatingeffect cannot be attributed to hydrogen ions.The interaction of nitroguanidine with hydrazine in dilute aqueoussolution a t 50-60" yields the interesting nitroaminoguanidine,NO,*NH*C( :NH)*NH*NH,, probably via an intermediate additive*O F.Arndt and B. Eistert, Ber., 1928, 61, [B], 1118; A,, 739; F. Arndt,B. Eistert, and J. Amende, {bid., p. 1949; A,, 1240.81 F. Schlotterbeck, Bsr., 1909, 42, 2669; A., 1909, i, 663.8% Bw., 1928, 61, [B], 1840; A,, 121790 ANNUAL REPORTS ON THE PROGRESS OF OHEMISTRY.compound. This new substance decomposes explosively at itsmelting point, reduces copper and silver solutions with formationof explosive metallic derivatives, and may be used in the quantitativeestimation of nickel. In addition, the blue colour of the nickel saltin alkaline solution provides a delicate qualitative test for thatmet al.83In the course of work on the synthesis of creatinol84 [N-methyl-N-( 8-hydroxyethy1)guanidinel it was found that the most satisfactorymethod for the preparation of amino-alcohols of the aminoethanoltype is to treat ethylene chlorohydrin with liquid carbonyl chlorideand to allow the resulting P-chloroethyl chloroformate to react withamines in benzene solution.The product is now a p-chloroethylalkylcarbamate, CH,Cl*CH,*O*CO*NHR, which can be decomposedby excess of alkali hydroxide to give the corresponding amino-alcohol, HO*Cl&*CH,*NHR. These aminoethanols may then betransformed into the guanido-alcohol either by the Erlenmeyermethod, in which a salt of the amine is allowed to react withcyanamide, or by Rathke’s method, in which the amino-alcohol istreated with a salt of S-alkyl isothiocarbamide.The mechanism ofthe latter reaction is still by no means clear and in the author’spaper the earlier addition theories85 are rejected and a decom-position theory is advocated in which the formation of cyanamidefrom the alkyl isothiocarbamide is postulated as a first stage, whichis then followed by the usual Erlenmeyer reaction. The synthesisof creatinol hydrobromide, which is cited as an example of thistype of reaction, is achieved by allowing 8-ethyl isothiocarbamidehydrobromide to react with methyl-P-hydroxyethylamine in thepresence of a little water. The free base is sensitive to the action ofalkali, but the salts are stable towards acids.Pure crystalline alanine may be obtained from pyruvic acid bysubmitting the latter to the simultaneous action of hydrogen andammonia in the presence of colloidal palladium stabilised by starchpaste .*6A more convenient method for the preparation of arginine fromgelatin has been described 8’ and in the s m e paper the transformationof arginine into glycocyamidine hydrochloride is reported.This is88 R. Phillip and J. F. Williams, J . Amer. Chem. Soc., 1928, lio, 2466; A.,84 H. Schotte, H. Priewe, and H. Roescheisen, 2. physiol. Chem., 1928,85 H. Lecher and F. Graf, Ber., 1923,58,1326; A., 1923, i, 761 ; H. Lecher,86 Aubel and Bourguel, Cornpt. rend., 1928, 188, 1844; A., 868.M. Berpann and L. Zervas, 2. physiol. (%ern., 1927, 172, 277; A.,1229.174, 119; A,, 1122.Z. physiol. Chem., 1928, 176, 43; A., 1123.1928, 612OBOANIC CHEiMISTRY.-PART I.91carried out by careful treatment of triacetyl anhydro-arginine withglycine ester, the resulting ethyl ester of diacetyl glycocyamine beingheated with hydrochloric acid a t 100". The hydrochloride ofglycocyamidine (I) thus obtained has also been prepared by heatingglycocyamine (11) in a sealed tube with fuming hydrochloric acida t 140".Another method 88 for the preparation of glycocyamidine consistsin the interaction of guanidine and ethyl aminoacetate a t 0", areaction which suggested a possible method for the detection ofesters from polypeptides. That this expectation was not realisedmay perhaps be due to the delicate nature of the reaction, which isinhibited completely by the presence of ammonia. The reactionmechanism suggested by the authors involves the loss of ammoniafrom the guanidine, followed by the union of the amino-acid withnascent cyanamide.When a-amino-acids are warmed with acetic anhydride andpyridine, carbon dioxide is eliminated and an a-acetamido-ketone isproduced by the attMhment of acetyl groups to the nitrogen andto the a-carbon atom :Certain other acids undergo a similar change, benzyl methyl ketonebeing formed in this way from phenylacetic acid, but alkylamino-acids, @-amino-acids, and amino-acids which contain no replaceablehydrogen in the a-position undergo simple acetylation withoutfurther change.Furthermore, the azlactones formed from leucine,phenylalanine and aspartic acid by the action of acetic anhydride,yield with acetic anhydride and pyridine the same acetamido-ketones as do the corresponding amino-acids.The suggestion istherefore made that the azlactones are formed as intermediatecompounds during the reaction, which may involve also the formationof a @-ketonic acid at one stage.89Experiments carried out by L. Zervas and M. BergmanngO haveserved to show that the substance produced by the auto-condens-ation of arginine ester and considered by Fischer and Suzuki to bearginylarginine is in reality optically inactive as-diguanido-n-valeric anhydride, NH2*C( :NH)*NH*[ CH2],*CH<NH-c .NH. Thelatter substance has been synthesised by the condensation of arginine8 8 E. Abderhdden and H. Sickel, 2. physiol. Chem., 1928, 173, 61 ; A,, 611.89 H. D. DakinandR. West, J .Biol. Chem., 1928,78,91,745; A., 874,1120.90 Ber., 1928, 61, [B], 1106; A,, 874.R.CH(NHJ.CO2H + (CH,*CO),O -+ R*CH(NH*CO*CHJ*CO*CH.SCO-YH 92 ANNUAL REPORTS ON THE PaOGRlSS OF CHEMISTRY.with S-ethyl isothiocarbamicle and found to be identical with theso-called “ arginylarginine.” It appears that, on the ‘liberation ofarginine ester from its hydrochloride, interaction takes place betweenthe ester group of one molecule and the guanido-group of another,giving a very unstable ester of arginylarginine, from which as-diguanidovaleric anhydride is produced by loss of ornithine methylester, followed by internal ring closure in the residue.Hydantoin-3-acetic acid yields on hydrolysis a glycylg1ycine-N-carboxylic acid which has been formulated variously asCO,H*NH*CH,*CO*NH*CH,*CO,H 91and as CO,H*NH*CH,*C( OH):N*CH,-C02H.92 It is now found thathydantoin-3-acetic acid is transformed by ammonia into a diamideidentical with that formed from ammonia and carbonyl bisglycineester, and that the ester prepared by the action of carbonyl chlorideon glycine ester is identical with the ester of glycylg1ycine-N-carboxylic acid. For these reasons it is now suggested that thecorrect structure of the last-named acid is given by the formulaCO (NH* CH2*C02H)2.93Further investigation of oxidation and reduction reactions withcystine and cysteine indicates that, in the absence of some thirdcomponent, neither reduced indigo nor reduced indigo-carmine canbe oxidised by cystine.The activating agent is not iron, whichcan, however, influence the reaction velocity, but seems to be anunstable oxygen or sulphur additive product of indigo-carmine whoseessential function is to activate the sulphur atom, whereupon thelatent reducing or oxidising power of the -SH or IS, groups isbrought into play.9*An improved method has been employed in the isolation ofphosphocreatine, which has been obtained as the calcium derivative,to which is assigned the composition C4H,0,N,PCa,4H,0. Thestructure suggested is PO( OH),*NH*C(:NH)*NMe~CH,*C02H, whichrenders this substance the first compound containing phosphorusattached to nitrogen to be isolated from natural sources.1 Thcquestion of its importance in the series of chemical changes involvedin muscular contraction is as yet undecided.2Organa -metallic Compounds.Beryllium alkyl derivatives are obtained by allowing anhydrousberyllium chloride to react with magnesium alkyl halides in the9l E.Fischer and E. Fourneau, Ber., 1901, 34, 2868; A., 1901, i, 676.92 H. Leuchs and P. Sander, Ber., 1925, 58, 1528; A., 1926, i, 1248.93 F. Wessely and E. Komm, 2. physiol. Chem., 1928, 174, 306; A., 623.94 E. C. Kendall and D. F. Loewen, Biochem. J., 1928, 22, 649; A., 1122.1 C. H. Fiske and Y . Subbarow, Science, 1928, 67, 169; A., 744.D. Ferdmann (with 0. Feinschmidt), 2. phy8ioZ. Chem., 1928, 178, 62 ;A,, 1267ORGAKW CHEMISTRY.-PmT I. 93complete absence of oxygen. The interaction of the metal withmercury alkyls fails to give the beryllium compounds, althoughthis method may be used to prepare the aryl derivatives.Thealkyl derivatives combine very readily with oxygen. The dimethyland diethyl compounds are spontaneously inflammable, but beryl-lium di-n-butyl oxidises more smoothly, yielding butyl alcohol andprobably beryllium n-butyl oxide. The beryllium alkyls reactviolently with water to form the corresponding hydrocarbon.Carbon dioxide reacts with beryllium dimethyl and yields aceticacid, but with the diethyl derivative triethylcarbinol is formed.Differences in reactivity between the dimethyl and the diethylcompound are revealed also in certain other reactions, such astheir interactmion with benzophenone, the former giving in this casediphenylmethylcarbinol and the latter, by reduction of the ketone,benzhydrol.3 Beryllium alkyl halides, BeRX, are also described.They are prepared by heating beryllium with alkyl iodides in thepresence of mercuric chloride, and in general they are less reactivethan either the beryllium dialkyls or the Grignard compounds.4Some organo-metallic compounds of thallium and of platinumhave been prepared, and have special interest from the point of viewof the co-ordination theory of valency.They are obtainable eitherby the double. decomposition of thallium dialkyl halides withcompounds such as thallium acetylacetone, or by the action ofthallium dialkyl ethoxide or dialkyl carbonate on the appropriatediketone. In this way thallium dimethyl acetylacetone and thecorresponding diethyl derivative were obtained as well as thalliumdimethyl benzoylacetone and analogous compounds.They are allcrystalline compounds with unusual properties. When heated underdiminished pressure they sublime, and in benzene and hexane theydissolve readily, giving non-ionised solutions. Their properties,therefore, are exactly those to be expected of chelate co-ordinatedcompounds with the structure (I) :CMe-0\clle:Of‘PtMe, (11.1 (1.) CHH \TlMe,In aqueous solution the covalent state gives place to an ionisedcondition, the solutions are now alkaline in reaction, and the thalliumdialkyl can be titrated quantitatively.5The analogous platinum compound (11) is obtained from thallousH. Gilman and F. Schulze, J., 1927, 2663; A,, 1928, 50.Idem, J . Amer.Chem. SOC., 1927, 49, 2904; A,, 1928, 60.R. C. Menzies, N. V. Sidgwick, E. F. Cutcliffe, and J. M. C. Fox, J., 1928,Compare F. Feigl and E. Backer, Monntsh., 1928, 49, 401 ; 1288 ; A., 746.A. 112694 ANNUAL REPORTS ON THE PROBRESS OF CHEMISTRY.acetylacetone and trimethyl p3atinic iodide. Like the correspondingthallium compounds, it may be sublimed unchanged.6A further examination of the reaction between sodium andpropionamide and butyramide in benzene shows that the mainproduct is the derivative R*CO*"a and that there is no markeddifference between the action of sodium and potassium. Evidencein favour of this view is furnished by the observation that propionylchloride and the product formed by the action of sodium on pro-pionamide yield dipropionamide.7The interest taken in Grignard's reaction and its applicationscontinues unabated and it will be possible to indicate only a few ofthe new observations which have recently been described.Un-certainty still remains concerning the structure and even the mole-cular weight of the magnesium alkyl halides. As the result ofevidence gained by determinations of molecular weight in etherealsolution, Terentiev 8 advocated the formula Mg(Alk,MgI,,2Et20),but it now appears that such experiments are complicated by thestrong tendency towards association shown by these compounds.Under suitable conditions the molecular weight corresponds tothat required by the formula Alk.MgI1 z (OEt,),. Thus in dilutesolution magnesium ethyl bromide exists mainly as the complexEtMgBr f 15 (OEt,),, only small amounts being ionised or poly-merised.Exactly analogous observations have been made withmagnesium iodide dietherate and there appears to be no validreason for postulating the existence of bimolecular compoundsduring the reaction between magnesium methyl iodide and water.gThe magnesium alkyl and aryl compounds in ethereal solutionundergo autoxidation unless oxygen is rigidly excluded. A detailedstudy of this reaction has now been contributed in the course ofwhich the authors make certain suggestions concerning themechanism of the reaction between magnesium methyl iodide andoxygen. The first stage of this is considered to lead to the formationof the complex (MeMgI 9 - 3 0 - - MeMgI,Et,O) which may decom-pose in a t least two ways.In the one case, by means of a uni-molecular reaction, the two iodine atoms are replaced by oxygen,and the liberated iodine reacts in the known manner with un-changed magnesium methyl iodide. The newly formed complex6 R. C. Menzies, J., 1928, 565; A., 609.7 A. Parts, Ber., 1927, 60, [B], 2520; A., 1928, 168.8 2. anorg. Chem., 1926, 156, 73; A., 1926, 1130.0 J. Meisenheimer, Ber., 1928, 61, [B], 708; A., 624; J. Meisenheimer andW. Schlichenmsier, ibid., p. 720; A,, 626. See also Q. Mingoia, Gazzettu,1928, 58, 532; A., 1266. Contrast L. Eierzek, Bull. Soc. chim., 1927, [iv],41, 1299; A,, 1927, 1176; andD. Ivanov, Corrvpt. rend., 1927, la, 605; A,,1927, 961ORUANIC CHEMISTRY.-PART I. 95(MeMg - - 3 0 MgMe,Et,O) then decomposes, giving MgO andMg(OMe),.In the second case, a bimolecular reaction is responsiblefor the oxidation, by the complex, of one molecule of MeMgI toMeOOMgI. The oxidation potential of the residue(MeMgI - - 2 0 MeMgI,Et,O)is thereby so much diminished that expulsion of the iodine no longeroccurs, and the oxidation now results in the formation of methoxy-residues. Both these reactions occur simultaneously in con-centrated solutions of the magnesium alkyl iodides, but the bimole-cular reaction is excluded in the case of iodides in diIute solu-tion. The unimolecular reaction invariably predominates withbromides .loThe interaction of magnesium alkyl halides and alkyl sulphonatesis usually represented by the equation2RS0,Alk + 2R’MgX --+ 2R’Alk + (RSO,),Mg + MgX,,which, however, does not agree with the results of more recentinvestigations.It now seems 11 that the product R’Alk is obtainedin yields never greater than 50% and that an equivalent amountof alkyl halide is formed simultaneously.(a) RS0,Alk + R’MgX --+ R’Alk + RS0,MgXand (b) RS0,Alk + RS0,MgX --+ AlkX + (RSO,),Mgis now suggested and experimental evidence in its favour is providedby the separation of n-butyl iodide and magnesium naphthalene-2-sulphonate from the products of reaction of iodo-magnesiumnaphthalene-2-sulphonate and n-butyl p-toluenesulphonate. Im-proved yields of the derivative R’Alk are, however, claimed byS. S. Rossander and C. S. Marvel 12 for the particular case in whichone molecule of a Grignard reagent containing six or more carbonatoms reacts with two molecules of y-chloropropyl p-toluene-sulphonate.This provides a method whereby a carbon chain maybe lengthened by three carbon atoms. A different reaction mechan-ism, not favoured by Gilman and Heck, is advocated by theseauthors.The utilisation of mixed magnesium alkyloxyhalides, RO-MgX,which are prepared by the action of magnesium alkyloxides onetherated magnesium halides, has been studied by V. Grignard andM. Fluchaire.ls Neither the etherated halides nor the magnesiuml o 5. Meisenheher and W. Schlichenmsier, Bw., 1928, 61, [BJ, 2029; A.,1232.l1 H. Gilmsn and L. L. Heck, J . Arner. Chem. Soc., 1928, 50, 2223; A,,1124.le Ibid., p. 1491; A., 732.la Ann.Chh., 1928,[x], 9, 6 ; A., 396.The schem96 BNNUAL REPORTS ON THE PROQRESS OB CHEMISTRY.alkyloxides act as condensing agents and a mixture of the two isinactive until the reaction MgX, + Mg(OR), o_, 2ROaMgX hastaken place. With aldehydes in the presence of mixed magnesiumalkyloxyhalides, two simultaneous reactions are observed : (I) aldolformation, and (11) ester formation, SRCHO + R*CO,*CH,R. Forinstance, acetaldehyde and magnesium butoxyiodide in the presenceof ether yield ethyl acetate, aldol, and butyl acetate, the formationof the last substance being due to the interaction of ethyl acetateand the magnesium derivative. The production of esters is explainedby the intermediate formation of a semi-acetal,l4 the subsequentcondensation of which yields the ester :RGHO + BuO*MgI + BuO*CHR*OMgI2BuO*CHR*OMgI --+ BBuO*MgI + HR.0.HR LJ HR.0. HR --+ R*CO,*CH,R. LFAldol formation is represented by the equationCHO*CH,R + BuO*CH(OMgI)*CH,R +BuOH + CHO*CHR*CH(OMgI)*CH,RSometimes, as with furfuraldehyde, reduction to the alcohol takesplace, R*CHO and BuO-MgBr giving CH,Pr*O*CHR*OMgBr, whichthen decomposes into PrCHO and CH,R*OMgBr.Methyl alkyl ketones react in accordance with the scheme2RoCOMe --+ R*CO*CH,*CMeR*OH and from the alcohols so formedunsaturated ketones of the type R*CO*CH:CMeR are readilyobtainable. In certain cases, e.g., when methyl isobutyl ketonereacts with magnesium butoxybromide and benzoyl chloride, theenolising effect of the organo-metallic compound becomes evidentand an ester of the enolic form of the original ketone is producedt o some extent.In this case the first stage is represented byBuO*CR’(CH,R)*OMgBr .+ BuOH + CHR:CR’*OMgBr, and in thepresence of benzoyl chloride the ester CHR:CR’-0,CPh is thenformed.The addition of sodium to ethylenic substances takes place onlywith those compounds which have aryl groups attached to thecarbon atoms concerned in the ethylenic bond. Numerous examplesin support of this conclusion are cited by W. Schlenk and E. Berg-mann 15 in the course of their lengthy and important communication,comprising more than 350 pages, on the chemistry of the alkali1‘ Compare A. Verley, Bull. SOC. chirn., 1926, 37, 837; A., 1926, i, 783;Ann. Report%, 1926, 22, 72; 1927, 24, 92.An&, 1928, 463, 1; 464, 1; A., 1031Oa&BM(3 CHEMISTRY.-PART I.97metal-organic compounds. One exception only to this rule has beendiscovered and in this case the substance in question (I) so closelyresembles the fulvenes (11) in structure as to render the exceptionalbehaviour more apparent than real. I n general, addition may takeplace in one of two ways : (a) represented by CPh,:CPh2~+CPhPa*CPh,Na or (b) represented by 2CPh,:Cq + 2Na +CPh,Na*CH,*CH,*CPh,Na. In both cases the obvious tendency isfor sodium to attach itself only to arylated carbon atoms, and it isinteresting to find that in the fulvene series only C, combines withsodium [i.e., the reaction follows course (b)] unless C, is arylated.Lithium enters into additive combination more rapidly thansodium, and sometimes leads to compounds differing in configurationfrom those derived from the corresponding sodium compounds.For an account of a systematic survey of this problem and of thebehaviour of the alkali compounds towards water, carbon dioxide,alkyl halides, and many other reagents, reference must be directedto the original paper.Carbohydrates.Monosacchides and G1ucosides.-In studying the optical rotationof sugars in solution Hudson has relied to a considerable extent onthe classification of the sugars into a- and @-varieties.This hasbeen subjected to criticism 16 and it is pointed out that contradictoryresults are obtained when other physical constants are considered.It is necessary to determine more than one additive property and,when only two forms are present during mutarotation, the ratiokl/k2 = K must be constant.From observations of specificrotation and molecular volume the value K is 0-50 and 0.47 formannose, whereas from the index of refraction the value K = 0.64is deduced. It is thus concluded that more than two forms ofmannose are present in solution, although the a- and p-varietiespreponderate. A similar conclusion is also reached from the studyof the optical behaviour of galactose17 in aqueous solution. Themutarotation curves of a-galactose do not obey the unimolecularlaw, and the early stages of the changes are rapid. With P-galactosethere is no change of rotation during 4 minutes, after which time themutarotation proceeds rapidly, giving an inflected curve with al6 C.N. Riiber and J. Mimaas, Ber., 1927, 60, [BJ, 2402; A., 1928, 47.G. F. Smith and T. M. Lowry, J., 1928, 666; A., 610.REP.-VOL. XXV. 98 ANNUAL REPORTS ON THE PROGRESS OF OHEMISTRY.maximum a t about 10 minutes. Assuming the third variety ofgalactose to be a form p, the mutarotation is represented bya- =+ p @-, and the rotatory power of p is of the same order asfor @-galactose. It is calculated that at equilibrium the proportionsof each form present are : a-, 286% ; 8-, 59.5% ; p, 12%.Almost general unanimity of opinion has been reached in regardto the formulation of simple sugars as pyranoses when these occuras free hexoses or pentoses or in the form of their normal glucosides.C. S.Hudson is exceptional, however, in opposing 18 this view andprefers to represent glucose and its a- and p-glucosides as five-atomring structures. He included in this category also p-mannose,lyxose, and a-methyl-lyxoside. F’rom optical rotation values,combined with an extension of the additive principle of opticalsuperposition, Hudson has computed rotational effects which aresingular in all the above cases. Since they do not yield expectedvalues on the above statistical basis, the above-mentioned sugarsand their glucosides are given a five-atom ring structure as distinctfrom the six-atom ring structure which is conceded for galactose,arabinose, xylose and a-mannose.In a further reply to this argument other authors l9 have reviewedthe statistical method of Hudson and have demonstrated thatin its application to the ring-structure of sugars it gives rise tofallacious deductions which are contrary to the chemical facts.It isshown that, whilst Hudson’s value a (for the rotational effect ofthat part of a sugar which involves the carbon atom of the reducinggroup) is approximately a constant for the glucose, galactose, xyloseseries yet quite another value for the constant is furnished by theseries mannose, rhamnose, lyxose. Indeed, if the latter series hadbeen the commoner or more accessible sugars, this singularity wouldhave been credited to the former series and statistical conformitywould probably have been conceded to the latter.It is suggested, however, that the lack of statistical agreementin the two series is associated with the cis-configuration of thehydroxyl groups in mannose, rhamnose, and lyxose.The new@-form of lyxose has been isolated, and this is in every respect com-parable with 8-mannose.Moreover, as a final argument, a-methyl-lyxoside (I) has beenmethylated to give the crystalline trimethyl lyxose (11). Thisyields a S-lactone (111), which undergoes oxidation to d-arabo-trimethoxyglutaric acid (IV) .2018 F. P. Phelps and C. S. Hudson, J . Amer. Chem. Soc., 1928, 50, 2049;A,, 991; 8ee also Ann. Repor&, 1926, 23, 78.W. N. Haworth and E. L. Hirst, J., 1928, 1221; A., 740.*O E. L. Erst and J. A. B. Smith, M., p. 3147ORUANIO CHEMISTRY.-PART I. 99(1.1 (11.1 (111.) (Iv*)Two isomeric triacetyl methyl-lyxosides are known, and fromthe properties of these it is evident that the normal methyl-lyxosideis a lyxo-pyranoside.21Crystalline g-methylfructoside has long been known and haslatterly been recognised as 13-methylfructopyranoside.The recentisolation of the crystalline a-form is a matter of interest and im-portance.22 The a- and p-methylfructosides are seen to stand in thesame relation to each other as a- and p-methylglucosides and allof them are six-atom ring forms or pyranosides. It is very satis-factory that the missing form has now been discovered and thatfructose in its general relationships is brought completely into linewith other sugars.The interconversion of a- and p-hexosides has hitherto beenpossible by digestion with methyl-alcoholic hydrogen chloride.Anovel method of some utility is now devised whereby @-forms areconverted with facility into a-forms in non-ionising solvents con-taining stannic chl0ride.~3 In the presence of titanium tetra-chloride, tetra-acetyl @-methylglucoside is smoothly converted intothe a-variety ; the completely acetylated sugars also undergo asimilar change, but this is accompanied by the introduction ofchlorine : for example, p-glucose penta-acetate is transformed intoa-chloroglucose tetra-acetate. The reaction appears to be a generalone.By the use of a very active form of silver chloride the inversion 24of a-chloroglucose tetra-acetate to the p-compound occurs in 8-10minutes. The specific rotation of the latter differs by about 30"from that calculated by Hudson.It is suggested that the principleof optical superposition is not valid in these cases and that Hudson'smethods of calculation should not be applied.The remarkable way in which hydrogen of the hydroxyl groupsin sugars may be replaced by thallium when employed as thalloushydroxide has again been illustrated.25 This react.ion is likely21 P. A. Levene and M. L. Wolfrom, J. Biol. Chem., 1928, '78, 525; A., 991.22 H. H. Schlubach and G. A. Schroter, Ber., 1928, 61, [B], 1216; A., 873.23 E. Pacsu, ibid., pp. 137, 1508; A,, 275, 1118.24 H. H. Schlubach, P. Stadler, and I. Wolf, ibid., p. 287; A., 398.25 R. C. Menzies and (Miss) M. E. Kieser, J., 1928, 186; A., 275100 ANNUAL REPORTS ON W E PROURESS OF CHEMISTRY.to prove of great value in effecting the protection of hydroxylgroups in difficult cases.By treatment with dilute alkali methylated augars are shown toundergo the Lobry de Bruyn and von Ekenstein transformation inmuch the same way as the unsubstituted sugars. For instance,tetramethyl glucose is convertible 26 into tetramethyl mannose,thus confirming the work reported last year on the identity of thering structure in each of these sugars.Elimination of phosphoric acid residues in sugars is accomplishedby the agency of bone phosphatase.By this procedure the a- andp-methylhexosidediphosphoric acids give rise to a- and p-methyl-hexosides and it is suggested by the authors that these are recog-nisable as a- and P-methylfructofuranosides. Thus it wouldappear that the sugar residue occurring in these compounds isy-fructose.27 Deductions based on magnitudes of specific rotationshould, however, be accepted with caution, and in the case underreview the authors would doubtless be well advised to confirm thisimportant conclusion by applying other and more certain methodsof diagnosis.Compounds having unsaturated sugar chains have long beenrecognised in the series known as the glucals.A sugar derivative,having an ethylene bond in the side chain of the ring, is nowavailable 28 in the compound a-tetra-acetyl glucoseen (V). Theproperties of this substance suggest a relationship to the transitionproducts between glucose and lignin or the compound from whichlignin arises biologically.A general study of the use of triacetyl glucose-1 : 2-anhydride (VI)has illustrated the facility with which this reagent 29 combines withhydroxylated compounds with the format'ion chiefly of p-glucosides.Ha *OAc 4',1 H * ? ! qHO*Y*H H*TGl H.7Ac0.F-H AcO$7*HH*(j*OAc I H*F*OAc 1 H*Q*OHH.7 - He?--CH,-OAc CH,*OH F(VII.)CH2(V.1 FI.1With phenol the reagent yields, however, a-phenylglucoside.A., 509.1214.A26 M. L. Wolfrom and W. L. Lewis, J . Amer. Chem. Soc., 1928, 50, 837;27 W. T. J. Morgan and R. Robison, Biochem. J., 1928, 22, 1270; A.,28 B. Helferich and E. Himmen, Bet-., 1928, 61, [B], 1826; A,, 1221.29 W. J. Hickinbottom, J., 1928, 3140ORGANIC CHEMISTRY .-PART I. 101comparison of the properties of the anhydride with those of Pictet’sa-glucosan (VII), which should be the parent substance of the above1 : 2-anhydrideY shows a certain disparity, since a-glucosan is saidto be capable of crystallisation from methyl alcohol, whereas thesubstance (VI) combines readily with methyl alcohol to yield theglucoside. The structure allocated to (VI) is, however, supportedby the observation that methylation of the glucoside to which itgives rise, followed by elimination of the glucosidic group and ofthe acetyl residues, leads to the recognition of a %methyl glucose.If a-glucosan has the constitution (VII), its properties present someunaccountable difficulties.More than usual interest attaches to Fischer and Zach’s anhydro-glucose, which is recognised as the 3 : 6-glucose anhydrideVHY ?HQHCH0.C- C -C--C-CH,H I A B IL-0-Jand, unlike glucose, has the property of restoring the colour ofSchif€’s reagent. The constitution here assigned is supported by anew method30 of preparation of the anhydro-sugar from glucosemonoacetone : the latter yields a di-p-toluenesulphonyl derivativewhich, on treatment with 1 mol.of alkali, is converted into acrystalline mono-p-toluenesulphonyl derivative of the above.Further treatment with alkali effects the removal of the remainingtoluenesulphonyl residue, yielding anhydroglucose-monoacetone , acrystalline substance. Elimination of the acetone residue is broughtabout by dilute acids and the free anhydro-sugar is then isolated inthe crystalline state.Among several unexpected results is the observation 31 thata-methylmannoside, which is known to have the pyranose structure,is converted into the diacetone compound of a-methylmanno-furanoside by the agency of 1% of hydrogen chloride in presence ofacetone.It would appear that under these conditions the six-atomring form is transformed into a five-atom ring form in order toaccommodate the two acetone residues which simultaneously con-dense with the four exposed hydroxyl groups. It is known that thiatype of change occurs readily in the free sugar, and the a-glucosideform is now seen to respond to the same structural change. Theacetone derivatives of xylose have long defied constitutional in-3O H. Ohle, L. von Vargha, and H. Erlbach, Ber., 1928, 61, [B], 1211; A.,871; K.Freudenberg, H. Toepffer, and C. C. Andersen, ibid., p. 1760; A,,1223.31 P. A. Levene and G. M. Meyer, J . Biol. Ohern., 1928, 78, 363; A,, 992.Compare also ibid., pp. 1208, 1870; A., 871, 1220102 ANNUAL REPORTS ON THB PROGRESS OF UHEMISTRY.vestigation, and speculation as to the possible occurrence in thesecompounds of a four-atom ring type of xylose has been current. Itis now demonstrated 3, that xylose-monoacetone is a derivative ofxylofuranose, since methylation yields a dimethyl derivative which,on hydrolysis and oxidation, passes into a 3 : 5-dimethyl yxylono-lactone (X). This is converted into the trimethyl y-xylonolactone(XI) which had previously been identified, and is now shown toyield a crystalline phenylhydrazide. The hydration curves of thelactone and its acid are given and are compared with those from theisomeric trimethyl S-xylonolactone.Moreover, oxidation of the7-lactone with nitric acid yielded d- dimet hox y succinic acid.It is shown that xylose-monoacetone must have the constitution(IX) and consequently that the diacetone is preferably representedby (VIII).Di-, Tri-, and Tetra-saccharides.-F'irst in importance among thepublications of the year on this topic is the communication byPictet and Vogel on the synthesis of sucrose. It will be remembered(Ann. Reports, 1916,13,90 ; 1920,17,65) that twelve years ago theadvance made in the study of sucrose led to the overthrow of theconstitution which had, up to that time, been accepted. Up to1916 it had been tacitly assumed that, since invert sugar consists ofa mixture of glucose and fructose, the forms of the sugars thusisolated were of necessity the forms in which they are combined inthe disaccharide.It was then founds that methylated sucroseshowed no inversion of sign on hydrolysis, and that, whilst the usualform of tetramethyl glucose could be isolated from this product, themethylated ketose displayed a rotatory power and a reactiontowards permanganate which at once implied its structural relation-*' W. N. Haworth and C. R. Porter, J., 1928, 611 ; A,, 609.*I W. N. Haworth and J. Law, J., 1916,109, 1314OWANIC OHEMISTRY .-PART I. 103ship to y-glucose, and the methylated ketose component was there-fore recognised as tetramethyl y-fructose.Although only a pro-visional formula could then be allocated, sucrose was thus shown tobe a disaccharide in which the normal form of glucose was linkedwith a y-form of fructose. It was reported that “ a new formula forsucrose is thus indicated which accounts not only for the extremeease with which the disaccharide is hydrolysed, but also for theprevious failure to effect its synthesis.” Four years later theisolation of the actual fructose component as a dextrorotatorytetramethyl y-fructose was announced,a and preliminary attemptsto ascertain its ring structure were made. At that time all suchattempts to elucidate the structure of y-sugars were doomed tofailure so long as the normal sugars were rigidly accepted as butylene-oxide forms. This fallacy underlying the whole of sugar chemistrywas exposed and glucose and fructose were shown to have a six-atom ring structure.36 It was then made abundantly clear that theolder formulations of sugars as five-atom ring compounds had beenerroneously applied to these substances, and that this discardedformula actually applied to the series of y-sugars.The six-atomring sugars, related to pyran, were described as pyranoses: they- or five-atom ring sugars were related to furan and designatedfuranoses.Sucrose was then definitely a complex containing each of thetwo kinds of sugar rir1g.~6 The glucose component was present asglucopyranose, and the fructose component as fructofuranose, andin sucrose they were combined by mutual linking through theirreducing groups.It became evident that if a suitably substituted derivative ofthe dextrorotatory variety of fructose could be prepared (that is,a fructofuranose as distinct from the lavorotatory fructopyranose),a synthesis of sucrose might be attempted with definite prospect ofsuccess.After an exhaustive search such a derivative has now beenprovided in the dextrorotatory tetra-acetyl y-fructose which occursas a by-product to the extent of 3% in the preparation of the normalor pyranose form of laevorotatory tetra-acetyl fructose. It is nowcommunicated by Pictet and Vogel37 that, when this tetra-acetyly-fructose (XII) is condensed with tetra-acetyl glucose (XIII) in achloroform suspension of phosphoric oxide, the genuine octa-acetylsucrose (XIV) is formed.By the elimination of the acetyl residuesW. N. Haworth, J., 1920,117, 199.?,ti Ann. Reports, 1925, 22, 83; 1926, 23, 74; 1927, 24, 66.88 Avery, Haworth, and Hirst, J., 1927, 2308; A., 1927, 1057.IW C-t. rend., 1928,186, 724; A., 510; Helv. Ch,h. Ack, 1928,11, 436;A., 741104 AXN'UAL REPORTS ON THE PROGRESS OF OHEMISTRY.the latter substance gives rise to sucrose identical in melting pointand optical properties with the natural product.It appears that sucrose, when crystallised from aqueous methylalcohol,% gives a modification (B), m. p. 171", whereas from mostother organic solvents the sucrose (A) separates, m. p. 185". Allthe properties of A and B are identical except the melting point, andthe conversion of B into A is instantaneous in water.The differencesin the two varieties seem to be purely physical.In another communication by the same authors 39 an account isgiven of the condensation of the usual lzevorotatory variety oftetra-acetyl fructose with tetra-acetyl glucose, yielding a disac-charide in which both the glucose and the fructose component arepyranose forms. The product, an isomeric form of sucrose describedas sucrose C, is crystalline and lsvorotatory and differs widely inproperties from natural sucrose. It is evident, therefore, that theearlier work on the constitution of natural sucrose is supported bythe synthetic experiments of Pictet and Vogel.The constitution assigned in previous work40 to melibiose hasnow been confirmed by a structural synthesis 41 of this disaccharide,which derives its importance from the circumstance that it occursas an essential component of raffiose.It was noted as a preliminarythat a-bromoacetogalactose, when heated with phenol and quinoline,yielded a mixture of a- and p-phenylgalactosides. The formationof this or-galactoside gave promise that, since melibiose has alreadybeen assigned an a-configuration, condensation of the abovea-bromoacetogalactose (XVI) with 1 : 2 : 3 : 4-tetra-acetyl p-glucose(XV) would yield a mixture of octa-acetyl glucose-a- and -p-galactosides from which octa-acetyl melibiose might be isolated.This has indeed proved to be the case. The octa-acetyl glucose-38 Gompt. mnd., 1928,186, 901; A., 1223.39 Idem, ibid., p. 905; A,, 1223.40 W.N. Haworth, J. V. Loach, and C. W. Long, J., 1927, 3146; A., 1928,166.R. Helferich m d H. Bredereck, Annalen, 1928, 466, 166ORUANIU (33HEMISTEY .-PART I. 105a-galactoside (XVII) was found to be identical with a specimen ofb%J0 (XVII.)The application of a similar procedure involving the condensationof (XV) with acetobromoarabinose led to the isolation of a hepta-acetyl derivative of the naturally occurring vicianose. Again, thelinking of cellobiose with gentiobiose has been accomplished with theformation of a synthetic tetrasaccharide of definite constitution,although this tetraglucose complex has not been identified with aknown natural product.A method of synthesis of raffinose is reported *2 depending on thefusion of sucrose and galactose, a procedure which is said to give a1% yield of the trisaccharide.A new tetrasaccharide, which isdesignated maltotetrose, has also been obtained by condensation ofhepta-acetyl maltose, and other new sugars of the trehalose type 43are obtainable by the similar treatment of p-tetra-acetyl hexoses intoluene containing zinc chloride to which phosphoric oxide issubsequently added.From the products of fermentation of glucose or fructose, inpresence of phosphate, a phosphoric ester of a disaccharide has beenisolated. This loses a phosphoric acid residue by the agency ofbone phosphatase and liberates trehalose,M thus affording a synthesisof thh non-reducing disaccharide.Other disaccharides which are entirely synthetic in origin have beenprepared by Freudenberg45 and his co-workers.They have4a H. Vogel and A. Pictet, Hdv. Chim. Acta, 1928, 11, 898; A., 1224.4* H. Vogel and H. Debrowska-Eurnicka, ibid., p. 910.44 R. Robison and W. T. J. Morgan, Biochem. J., 1928,22,1277; A., 1286.K. Freudenberg, H. Toepffer, and C. C. Andersen, loc. cit. ; K. Freuden-berg, A. Wolf, E. Knopf, and 8. H. Zaheer, Ber., 1928,61, [B}, 1743 ; A., 1222.D 106 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.utilised for this purpose glucose-6-bromohydrin (XVIII). Bysuitably protecting two hydroxyl residues in this compound, e.g.,by an acetone group or two acetyl groups, two hydroxyl positionsremain available for condensation, as in the compound (XIX).This has been combined with acetylglucosido-halides of severaltypes, and derivatives of new dihexoses are made available.Other similar experiments have led to the isolation of synthetictrisaccharides of the type (XX).H,Brr- 1Experiments of great interest and value have also been com-municated by the same author 46 dealing with the rates of hydrolysisof disaccharides, glucosides, and sugar-acetones.The figures forthe inversion constants of most of the known compounds are thusmade available for comparison.PoZysacchccrides.-Experiments on the constitution of inulin haverevealed 4’ the points of junction of contiguous residues of fructo-furanose (y-fructose). Methylation of inulin yielded a ‘‘ trimethylinulin,” which was hydrolysed to give 3 : 4 : 6-trimethyl fructo-furanose (XXI). This yielded a crystalline osazone and underwentoxidation to a 3 : 4 : 6-trimethyl fructuronic acid (XXII).Thelatter was converted, after methylation, into the same crystallineamide as that which had previously been obtained from tetramethylfructofuranose derived from sucrose. The presence of the sameform of fructose in both sucrose and inulin was thus confirmed.Oxidation of the trimethyl fructuronic acid with acid permanganateled to the isolation of the crystalline d-2 : 3 : 5-trimethyl y-arabono-46 I(. Freudenberg and others, Ber., 1928,61, [B], 1735; A,, 1222.4 7 W. N. Haworth and A. Learner, J., 1928, 619; A, 610ORQANIC aHEM1STRY.-PART I. 107lactone (XXIII).to Z-dimethoxysuccinic acid (XXIV,.This is characterised by its oxidative degradationQ02H Hi@?----H.F-Ap W H+ - M e O * F y bH*$?*OMe ICH,*OMe(=.I (=I.) (XXIII.)From these results it is shown that the union of the y-fructoseresidues in inulin occurs through the positions 1 and 2 in each sugarchain. This structural scheme is indicated below.On this view, the simplest expression for inulin is the followingformula,O-------CHCH,*OHCH(OH)-(!H-OHwherein two fructose anhydride units are mutually linked.Valuesfor molecular weight determinations of triacetyl inulin have beenreported which correspond to hexa-acetyl difructose anhydride?and moreover the complexity of inulin in liquid ammonia isseen to be in agreement with this simple expression. An endeavourto synthesise a compound having this simplified structure hasrecently been made.48On the other hand, direct determinations of the molecular weightof inulin in water indicate the presence of a more complex molecule,containing at least 24 anhydro-fructose ~nits.4~ Hydrolysis of theinulin in warm water is shown, however, to be progressive andafter 28 minutes the above value is diminished to half and thereducing power of the solution increases as the molecular weightdiminishes.Under other conditions inulin breaks down readily togive a “laevulin” corresponding to six or eight C6Hlo05 units. EarlierH. H. Schlubach and H. Elmer, N U t U ? ~ i 8 8 . , 1928, 16, 772; Ber., 1928,81, [ B ] , 2358; A., 1221.H. D. K. Drew and W. N. Haworth, J., 1928, 2690; A,, 1360108 ANNUAL REPORTS ON THE PROGRESS OF UHEWSTRY.determinations of molecular weight have been commented on inprevious Reports.Others are now communicated 50 correspondingto complexes varying from (C,H,,O,), to (C,H,,O,),. The formervalue is obtained by the cryoscopic method with aqueoussolutions of inulin. But by heating inulin acetate (at temperaturesvarying from 250" to 290") in presence of tetrahydronaphthalenethe values diminish progressively to the above minimum. Whetherthis diminution corresponds to dissociation or decomposition is aproblem remaining for future decision.Inulin itself, heated with glycerol a t 120"/15 mm., is found61to undergo definite structural change to a trilaevulosan, and at aslightly higher temperature a dilaevulosan which reduces Fehling'ssolution is reported to be the product. It is doubtful, therefore,whether the transformations of inulin acetate already discussed canbe interpreted as a simple dissociation or depolymerisation of inulinto its " structural unit."Recent experiments 5, have shown that the methylation ofcellulose a t 20" with methyl sulphate gives rise to a trimethylcellulose which differs essentially from the specimens previouslyisolated. This is soluble in chloroform, tetrachloroethane, andacetic acid, giving clear viscous solutions, and is quite insolublein water.The yield is 93% of trimethyl cellul0se,5~ and this onhydrolysis furnishes 2 : 3 : 6-trimethyl glucose in a yield of 91%,but in no case could a trace of tetramethyl glucose be isolated.This establishes the structural identity of all the glucose units incellulose.When it was heated with hydrogen chloride in ethersolution, the trimethyl cellulose yielded 1 -chloro-2 : 3 : 6-trimethylglucose, which, in contact with sodium, was transformed into acompound described as 2 : 3 : 6-trimethyl glucose anhydride.According t o 6ome earlier theories such a compound would beexpected to be the '' structural unit " of trimethyl cellulose. Butthe complete dissimilarity of the anhydride with the latter provesthat cellulose cannot be regarded as a unimolecular glucose anhydride.There appeared to be no grounds for the suggestion that trimethylglucose anhydride would undergo reversible interconversion intotrimethyl cellulose. The author thus falls back on the older tradi-tional view that cellobiose is the true breakdown product of celluloseand is not a reversion product. It is held to be probable that cello-biose residues comprise the essential units of cellulose and that these60 H.Pringsheim and I. Fellner, Annalen, 1928, 482, 231; A,, 742; H.Pringsheim and J. Reilly, Ber., 1928, 61, [B], 2018; A., 1226.61 H. Vogel and A. Pictet, Helv. Chim. Acta, 1928, 11, 216; A., 276.62 H. Urban, Cellulosechem., 1926, 7, 73; B., 1926, 631.63 K. Freudenberg and E. Braun, Annalen, 1928, 480, 288; A,, 399; I(.Freudenberg, ibid., 461, 130 ; A,, 743ORGANIC CHEMISTRY .-PART I. 109are joined in a chain which is united throughout by ordinary co-valency links. A similar view has also been independently expressedby another worker,a and since the cellobiose structure has been finallydetermined it follows that this picture of the cellulose constitutionis given by the scheme :CH,.OH H OH CH,*OH H OHA re-interpretation of the crystal lattice of cellulose is held tosupport this view entirely.55 The elementary cell has the dimension10.3 8.along the fibre axis in ramie cellulose, and the other dimen-sions of the cell are given as 7.9 and 8 - 7 8 . This accommodatesfour glucose residues, and the first dimension is in close agreementwith two units of the six-atom ring form of glucose as arranged incellobiose. It is deduced that the expression formulated abovereceives strong support, the cellobiose residues being oriented in thedirection of the fibre axis and mutually linked by glucosidic oxygen.Forty or more glucopyranose residues are regarded as being joinedby p-glucosidic linkings in this way.It is suggested that thisstructural scheme is in harmony with the established chemicalproperties of cellulose and is compatible with and affords a readyexplanation of the behaviour of cellulose during esterification andswelling.Other interpretations of the X-ray data commented on in lastyear's Report66 anticipated in the main these features of thecellulose structure. In one essential detail, however, they differed,inasmuch as the occurrence of the 3.4 A. line offered difficulties inaccepting the cellobiose type of linking of the glucopyranose units.Instead of the union being 1 : 4-1 : 4 between contiguous glucoseresidues, the earlier authors preferred to arrange the linkings in theorder 1 : 4 4 : 1.But the ordered linking of glucopyranose unitsin long chains arranged side by side is the main conclusion of bothinterpretations of the X-ray diagrams of cellulose. Doubtless thesedifferences will be adjusted by further experimental work, whichshould be largely chemical in its scope.The experiments and conclusions of Hess 57 are entirely opposed6 6 K. H. Meyer and H. Mark, Ber., 1928, 61, [B], 593, 1936; A., 621; 2.W. N. Haworth, Helv. Chim. Acta, 1928, 11, 534.angew. Chem., 1928, 34, 935.Ann. Reports, 1927,24, 82.67 K. Hess and C. Trogus, Bey., 1928, 61, [B], 1982110 d14NUAL REPORTS ON THE PROGRESS OF CHEMISTRY.to these conceptions of the cellulose structure. This author con-siders that the above interpretations of the X-ray diagrams areinvalid in so far as they assume the presence of cellobiose residuesor of glucosidic disaccharide linkings. He urges that the dis-entanglement of the structural factors of cellulose in the X-raydiagram is rendered difficult by ignorance of the correspondingdiagrams of carbohydrates of known structure. The diagrams of anumber of such products are now given, and it is claimed that oneof these, a biosan (C12H20010) which the author has isolated fromcellulose, differs but little from cellulose in the mass distributionof its constituent atoms. The effect of substitution of groups onmass distribution is intimately considered. On this view a moreappropriate conception of the cellulose structure is that of anarrangement of masses of the biosan or glucosan complex united bydirected associative forces.In the past, difficulty has been encountered in the preparation oftriacetyl and trimethyl starch. Small yields of products wereobtained, in some cases after very prolonged and repeated treatmentswith the substituting agents. This led to serious doubts whetherthe final products were genuine derivatives of the original starchor of a portion only of the polysaccharide which had been segregatedduring these observations.In a new series of experiments * starch has been brought into acondition in which it is more susceptible t o reagents. Starch pastewas quantitatively precipitated with alcohol and gave a powderwhich retained the properties of the substance. On acetylationthis gave a 96% yield of a triacetyl starch. De-acetylationfurnished a product having the properties of regenerated amylose.Methylation of the triacetyl starch under new conditions gaverise to a trimethyl starch in 89y0 yield after only six treatmentswith the reagents. This is compared with the results of earlierworkers, who obtained a 25% yield after 24 methylations. It isshown that a high yield of 2 : 3 : 6-trimethyl glucose was obtainablefrom the methylated starch. The authors were unable to confirmearlier claims that starch undergoes preferential methylation to ahomogeneous dimethyl starch, and the structural views based on suchan observation are rendered doubtful. The probability that starchis largely composed of conjugated a-glucopyranose units is dis-cussed and alternative formula are considered.W. N. HAWORTH.E. L. HIRST.66 W. N. Haworth, E. L. Hirst, and J. I. Webb, J., 1928, 2681; A., 1360ORGANIC CHEMISTRY .-PART 11. 111PART II.-HOMOCYCLIC DMSION.IN this contribution the aim will be to bring up to date the accountof those subjects which, having been discussed in one or more of thecorresponding Reports since 1923, have subsequently made markedprogress. Other topics will be left aside that they may be dealt withby a future Reporter in a more connected manner than would bepossible if they were discussed at the present stage.Large Carbon Rings.(Continued from Ann. Reports, 1926, 23, 112-119.)Since the date of the Report referred to, a detailed examination byRuzicka and his collaborators of the distillates obtained fromthorium azelate and sebacate, from yttrium nonane- and decane-aw-dicarboxylate, from thorium pentadecane-, octadecane-, andnonadecane- aw-dicarboxylate, and from yttrium eicosane- andoctacosane-aw-dicarboxylate, has led to the isolation of a large numberof new cyclic and open-chain compounds. The cyclic substancesinclude hydrocarbons with rings of 16, 18, and 30 methylene groups,monoketones with rings containing 19, 20, 21, 29, and 30 carbonatoms, and a series of symmetrical cyclic diketones with 16,18,20,22,and 30 carbon atoms in their rings. The last group of substances areCO of the type (CH,)n<co>(CH2)n, of which the only previously knownexamples are the cyclobutane- and cyclohexane-diones.The following table contains a list, complete from C,, to Cm, of thesaturated, unbranched, cyclic hydrocarbons, monoketones, anddiketones which have been described up to the time of writing. Thefigures represent the m. p.'s of the compounds ; those in Roman typerelate to compounds the preparation of which is referred to in theReport for 1926, and those in italics to those which have beenprepared since that time.etc. etc.

ISSN:0365-6217    

DOI:10.1039/AR9282500067

出版商:RSC    

年代:1928

数据来源: RSC

摘要:

ANALYTICAL CHEMISTRY.DEFINITE advances in analytical practice have been recordedduring the year. Microchemical tests for various elements arenow attaining considerable importance, particularly for some ofthe rarer elements such as gallium, indium, and rubidium. Thedifficulties attending the analytical separation and estimation oftantalum and niobium may now be said to be overcome to it largeextent by the use of the tannic acid method of separation, andthe troublesome separation of beryllium from aluminium is nowpractically solved.A considerable amount of work has been devoted to the accuratedetermination of minute quantities of arsenic by the Gutzeitmethod. This work has been largely directed to prescribing theexact conditions essential for obtaining uniform results.Many papers dealing with potentiometric methods have appeared,and the ease of utilising the method in practice is again demonstratedby the extensive literature on oxidation-reduction methods.Thedifficulty underlying the use of alkali ferrocyanides when determin-ing the end-point potentiometrically in precipitation reactions hasalso been extensively investigated. This useful reaction has accord-ingly been extended in several directions where ordinary metlhodsof titration are clumsy or difficult to apply. Ceric sulphate in acidsolutions is found to be a very useful reagent in potentiometricwork, as will be gathered from its applicafion to the determinationof vanadium in steel and to its use in determining nitrites andperoxides amongst many other substances.An advantage of cericsulphate solutions is their stability when properly stored. Theuse of various metallic electrodes potentiometrically is extendingwith both " indicator " electrodes and " reference " electrodes,tungsten being found very useful in the latter class.A few investigators have taken up the consideration of tn-oimportant matters often neglected, vix., the adequacy of samplingin practice, and the incidence of unavoidable errors in analyticalmethods.I~~organic Analysis.Qualitative.-The formation of an insoluble reddish-violet saltwith p - dimethylamino benzylidenerhodanine, preferably in thepresence of carbon disulphide to act as solvent for excess of reagentAN4LYTICM.L UEEMISTRY. 199consiitutcs 1 a specific test for silver, far more delicate than thechloride reaction.In more concentrated solutions the character-istic rhombic crystals of the sulphate serve for the microchemicaldetection of silver.2 Further spot-tests on filter paper, referred toin recent Reports, embrace leadY3 silver, copper, mercury, chromium,and manganese.4 Lead, bismuth, copper, mercury, and silver areremoved from acid solution by iron or zinc powder prior to testingfor cadmium.Cathodic deposition of lead, which is promoted by the presenceof phosphoric acid, is not so delicate or satisfactory a qualitativetest as anodic deposition followed by the colour reaction withtctramethyldiaminodiphenylrnethane ; of the metals bismuth,mercury, iron, copper, cadmium, and manganese, the last aloneinterferes.6 The red coloration afforded by careful mixing of astannous solution with acidified diazine-green-S is a delicate testfor tin.7Diphenylcarbazide is much preferred to hydrogen peroxide andether as a reagent for chromium as chromate.* The test for ironwith dimethylglyoxime and hydrogen sulphide is, under certainconditions, about as sensitive as that with thiocyanate?The reactions of cobalt, both alone and also in the presence ofnickel and zinc, are described.l* Delicate cofour reactions for zincme given, metanil-yellow, orange-IVY or diethylaniline being usedin conjunction with potassium ferricyanide.7Magnesium salts which can be decomposed by sodium hydroxideare coloured reddish-violet when treated with an alcoholic solutionof diphenylcarbazide.ll Dolomite does not give the reactionunless previously heated to redness.From this fact the mineralis formulated as calcium magnesocarbonate, which is stated to besupported by X-ray ana1~sis.l~ A sensitive colour reaction formagnesium, applicable in the presence of fairly large proportionsof calcium, is given by Clayton-yellow followed by alkali.13 Con-F. Feigl, 2. anal. Chem., 1928, 74, 380; A., 1108.2 0. Hackl, Mikrochem., 1928,6, 106; A., 980.N. A. Tananaev, 2. anorg. Chem., 1927,167, 81; A., 1927, 1161.4 N. A. Tananaev and I. Tanmaev, ibid., 1928,170, 113; A., 500.P. G. Popov, Ukraine Chem. J., 1928, 3, 153, 158; A., 1206.6 P. W. Danckwortt and E. Jurgens, Arch. Pharnz., 1925,266,367; A,, 981.E.Eegriwe, 2. anal. Chem., 1928, 74, 225; A., 982.8 N. M. Stover, J . Amer. Chem. Soc., 1928, 5.0, 2363; A., 1206.R. Nakaseko, Mem. Coil. Sci. Kydtd, 1928, A , 11, 113; A,, 727.H. Fischer, Wiss. Ver6ff. Siemens-Konz., 1928, 6, (2), 147; A., 727.l1 F. Feigl, 2. anal. Chem., 1927, 72, 113; A., 1927, 1161; F. FeigI and H.l a F. Feigl, Z. anal. Chem., 1928, 74, 398; A., 1108.13 H. D. Barnes, J.S. African Chem. Inst., 1928, 11, 67; A., 1108.Leitmeyer, Zentr. Min. Geol., 1928, A , 74; A., 1206200 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.centrated zirconium sulphate is a fairly sensitive reagent for potass-ium in the presence of sodium.14 It is more useful in the presenceof ammonium salts which interfere with most other tests.15 Theuse of uranyl acetate as a reagent in microscopical analysis isdescribed for a number of metals.16 The delicacy of the formationof sodium zinc uranyl acetate is so great that silica object slidesshould be used instead of ordinary glass.The removal of phosphoric acid as the lead salt in qualitativetesting is described.17 Hexamethylenetetramine with ammoniumthiocyanate and piperazine with sodium iodide or bromide areused as microchemical reagents for a number of metals.18The formation of characteristic black crystals of a complexiodide with silver and gold serves to detect very small quantitiesof rubidium in the presence of sodium, potassium, or ammoniumsalts but caesium interferes.19 A seriea of microchemical tests,investigated to avoid the possible interference of other elementslikely to be present in minerals, has been described for iron, gallium,indium, palladium,20 tellurium, selenium, manganese,21 gold, andsulphur .22 Qusdrivalent iridium and osmic acid solutions givewith beiizidine blue coloration^.^^ In the absence of gold, copper,selenium, and the platinum metals, the reduction of tellurates andtellurites by titanous chloride in hydrochloric acid solution servesas a test for tellurium.2” For the detection of vanadate, it isrecommended to precipit.ate the vanadium with the metals of theiron group; hot sodium hydroxide then extracts from the washedprecipitate vanadium together with aluminium.25 Soluble vanad-ates, tungstates, and molybdates form with pyrocatechol acetatefollowed by aniline or piperazine characteristic coloured precipit -ates.26 Curcurnin gives with beryllium salts in ammoniacal solutiona reddish flocculent precipitate, but aluminium and ferric ironmust first be precipitated by addition of sodium fluoride.27l4 R.D. Reed and J. R. Withrow, J . Amer. C‘hein. Soc., 1928, 50, 1515; A,,558.l5 Idem, ibid., p. 2985.l7 G. G. Kandilarov, 2. anal. Chem., 1927, 72, 263; A., 1928, 144.19 E. S. Birkser and S. G. Rublof, Ukraine Chem. J . , 1926, 2, 355; I l l i k ~ o -20 P. C. Putnam, E. J. Roberts, and D. H. Selchow, Amer. J . Sci., 1928,fl Idem, ibid., p. 253; A., 498. 24 Idem, ibid., p. 46.6; A., 861.23 V. G . Chlopin, Ann. Imt. PZatine, 1926, 4, 324; A., 1927, 1162.2o 0. TomiEek, Bull. SOC.chin&., 1927, (iv), 41, 1399; A., 1928, 36.25 J. Roll, 2. anal. Chem., 1928, 74, 342; A., 983.26 A. Martini, Mikrochem., 1928, 6, 63; A., 387.27 I. M. Kolthoff, J. Amer. Ghem. SOC., 1828, 50, 393; A., 386.E. M. Chamot and H. A. Bedient, iklikrochein., 1928, 6, 13; A., 385.A. Martini, Mikrochem., 1928, 8, 28; A., 387.chem., 1927, 5, 137; A., 1928, 37.(v), 15, 423; A., 727ANALYTICAL CHEMISTRY. 201Vigorous evolution of nitrogen from a solution containing sodiumazide and iodine is induced by the addition of sulphide and thio-sulphate, but not by other compounds or by elementary sulphur ;minute quantities of even insoluble sulphides, e.g., in minerals, canreadily be detected. Arsenides, selenides, antimonides, and tellur-ides do not respond.28 On the basis of this reaction it is statedthat fusion of selenium and sulphur produces a true sulphide.Thepresence of the pentathionate ion may be detected in the presenceof sulphite by the appearance of an opalescence within 3 minuteswhen the solution is rendered slightly alkaline in the presence off ormaldehyde.29Hydrouylamine may be detected by means of the colorationwith p-bromonitrosobenzene and a-naphth~l.~~ Extensive tableshave been drawn up showing the colour changes produced in dyesby further diazotisation and coupling ; those substances bestsuited for the detection of nitrites are en~merated.~ISome microchemical reactions of various halogen acids have beendescribed.a2 Phosphates may be detected in the presence ofarsenates by the development of a blue coloration, either on filterpaper or in a test-tube, on treatment with nitric acid-molybdatesolution, benzidine, and ammonia.33Quantitative.-From mathematical coiisiderations of the theoryof probability, the relation between the minimum weight of asample to be taken for analysis and the degree of fineness of aheterogeneous mixture has been deducedY3* whilst the extent towhich results may be influenced by inaccuracies in measurementand observation has been considered for typical methods of chemicalanalysis.35 The merits of adipic acid and of oxalic acid dihydrateas analytical standards have been discussed .36 Metallic calciumof known purity can be weighed directly and dissolved in sucrosesolution to afford a carbonate-free standard alkali solution.37 Thechange of titre of thiosulphate solutions is attributed to the actmion2 5 F.Foigl, Z . anal. C'henh., 1928, 74, 369; A., 1106.29 A. Czernotzky, 2. nnorg. Chein., 1028, 175, 402 ; A,, 1204.3O J. Blom, Biochern. Z . , 1928, 194, 385; A,, 674.31 J. V. Dubski and A. OkB6, Publ. Fac. Sci. Cniu. dlasco.gl:, 1927, No. 83,32 E. M. Chamot and C. W. Mason, lMikrocheni., 1928, 6, 82; A,, 978.33 I?. Feigl (with P. Krumholz), Z. anal. Cheni., 1928, 74, 386; A.,34 J. Mika, ibid., 1928, 73, 257; A,, 496.35 F. Goudriaan, Chem. Weekblad, 1928, 26, 52; A., 262; B. D. Hartong,343 F. T. van Voorst, &id., p. 22; N. Schoorl, ibid., p. 73; W. P. Jorhen,37 A. C. Shead, J . Amcr. C'liott. XOC., 1028, 50, 415; A., 385.1 ; A., 1927, 1160; Z.anaE. CJbenL., 1928, '75, 92.1107.ibid., p. 105; A., 382.ibid., p. 90; A,, 1928, 262.0 202 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,of bacteria, of which there are three active The protectiveaction of alkali is ascribed to the restraining effect of alkalis onbacterial growths, which is greatest at pE 9-10. Complete sterilityis produced by the addition of 1% (by vol.) of amyl alcohol.The use of methyl-orange as indicator for the determination ofthe free acidity of solutions containing sulphates of zinc, copper,manganese, cadmium, or nickel gives results agreeing with thoseobtained potenti~metrically.~~ Errors in the titration of acids andbases can frequently be greatly reduced by carrying out the oper-ation in a non-aqueous medium such as acetone or 90% alcohoLMA table is set out correlating the various methods of expressing theacidity of solutions.41An accurate method of ascertaining the pH value of distilledwater is the colorimetric, with a diluted neutralised solution ofmethyl-red ; the quinhydrone-electrode method always involvesan error on the acid side, which, however, diminishes with suitablebuffering.42 A critical study of the various methods of preparingand adjusting certain indicator solutions is described, and it isrecommended that the pH value of the indicator should be adjustedto a point midway between the extremes for the particular indic-a t ~ r .~ ~ A series of 25 mixed indicators, with their colour changesat pH ranging from 3-25 to 10.8 has been compiled.44 Data aresupplied for determining % values between 6.7 and 10.0 with theaid of fast-green FCF.45 A series of indicator papers which becomegrey a t definite pH values, but assume positive colours at valuesabove or below the grey value, has been devised, covering the pHrange 1 45-84.46 The divanillylidenecyclexanones are excellentindicators, as sensitive as methyl-red ; the colour change occursfrom p , 7.8 to 9.4, that from 8 to 9 being so delicate as t o be avail-able for measuring pH in this interval.47 The speed with whichthe blue colour is developed by the reaction of malononitrile witha-naphthaquinone increases with increasing pE value between thelimits 2.5 and 11.5; small differences in the hydrogen-ion con-centration of solutions may be detected by this test.48 For solutions38 C.Mayr and E. Kerschbaum, 2. anal. Chem., 1928, 73, 321; A., 607.39 E. MiiIler and F. Muller, ibid., p. 47; A., 386.40 K. Linderstrom-Lang, Dan& Tidmkr. Farm., 1928, 2, 201 ; A., 977.41 A. J. J. Vande Velde, Natuuwetemch. Tijds., 1928, 10, 145; A,, 1203.42 C. van der Hoeven, Collegium, 1928, 440; A., 1203.43 W. H. Pierre and J. F. Fudge, J . Amer. Chem. SOC., 1928,50,1254 ; A., 723.44 I. M. Kolthoff, Biochem. Z., 1927,189, 26; A., 1927, 1159.45 W. C. Holmes and E. F. Snyder, J . Amer. Ohem. Xoc., 1928, 50, 1907;46 W. U. Behrens, 2. aml. Chem., 1028, '93, 129; A,, 496.4 7 B. Samdahl, J. Pham. C'hirn., 1928, (viii), 7, 162; A., 523.4 8 TV. Kesting, 2. awgew. Cherra., 1928, 41, 358; A,, 606.A., 976ANALYTIC& CHEMISTRY.203of relatively low pH value, benzoquinone gives a more delicatecolour change, while P-naphthaquinone is used at the other extreme.The behaviour of various indicators in certain titrations has beenand a study has been made, mainly from the academicside, of a number of azo-indicat0rs.m Determination of the pEof certain natural waters appears to be one of the best means ofascertaining the age of the water, since, on exposure, a gradualchange to alkalinity occurs, beginning in the upper portion of theliquid.51 Some buffer solutions for the alkaline range are de-and also some electrodes for p , determinations.=Investigation of the applicability of iodometry to micro-analysisshows that in the reaction occurring in solutions about 0-001N withrespect to iodate and containing excess of iodide and acid, thetheoretical quantity of iodine is liberated and a satisfactory end-point subsequently obtained only when the product of the con-centrations of iodide and acid lies between certain limits.Variousother reactions have also been examined.54Precipitation with ‘‘ cupferron ” from solutions containing freehydrochloric or nitric acid not exceeding N/l affords a rapid meansfor the complete separation of bismuth from cadmium, lead, zinc,arsenic, silver, and quinquevalent antimony.55 Two volumetricmethods of determining bismuth depending on precipitation of themetal either by aluminium or by copper are described. In onecase the cuprous chloride formed is titrated with potassium brom-ate, whilst in the other the metal is dissolved in acid ferric chloridesolution, the ferrous chloride formed giving the measure of thebismuth.56 A gravimetric process for micro-determination ofbismuth as the oxy-iodide is described; alternatively, the driedprecipitate may be heated in a currenf of air or oxygen and theliberated iodine collected in potassium iodide and titrated withthi~sulphate.~~ The former process has also been modified for usewith larger quantities of bismuth ; 58 in the presence of much lead, apreliminary separation of bismuth as basic bismuth formate is made.49 R.T. Thornson, Analyst, 1928, 53, 315; A., 857.5O A. Thiel and 0. Peter, 2. anorg. Chem., 1928,173, 169; A,, 977.51 G.Banchi, Giorn. Chim. Ind. Appl., 1927, 8, 518; A., 1928, 262.53 I. M. Kolthoff and J. J. Vleoschhouwer, Biochm. Z., 1927, 189, 191;Chem. WeekblQd, 1927, 24, 526; A., 1927, 1159.53 A. J. de la Cruz, Philippine Agric., 1927, 16, 307; A., 1925, 607; F.Grossman, Rocz. Chem., 1927, 7 , 567; A., 1928, 607; E. Biilmann, A. Klit,and T. Swsetichin, Biochem. J . , 1928, 22, 845; A., 857.54 P. Putzeys, Ann. SOC. Sci. Bruxdles, 1927, 47, B, i, 159; A., 1928, 144.5 5 A. Pinkus and J. Dernies, Bull. SOC. chim. Belg., 1928, 37, 267; A,, 1109.56 H. Kubina and J. Plichts, 2. a d . Chem., 1927, 72, 201; A,, 1928, 39.5 1 R. Strebinger and W. Zins, Mikrochem., 1927, 5, 166; A., 1928, 39.5 8 Idem, 2. a d . Chem,., 1927, 72, 417; A., 1928, 688204 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The amount of chloride present in cadmium sulphide precipit-ated from hydrochloric acid solution depends on the acid con-centration and the pressure at which precipitation is made.59 Thephenomenon is one of adsorption and is not due to the formationof a double salt.Cadmium can be rapidly determined by appro-priate treatment of the precipitate given by pyridine and thio-cyanate, whereby the compound is weighed as such; 6O lead isprecipitated by these reagents as basic thiocyanate, which may bedealt with in a similar manner.61 The blue coloration given byleatl peroxide with a solution in acetlic acid of tetramethyldiamino-ciiphenylmethane has again been applied to the detection anddetermination of lead ; 62 iron and other impurities reduce theaccuracy of the method.A study has been made of the gravimetric determination ofcopper by the thiocyanate method, which may be applied in thepresence of cobalt, nickel, zinc, manganese, arsenic, and iron, and,if tartaric acid be added, of antimony, bismuth, and tin.63 Sulph-ides, e.g., of mercury, nickel, and cobalt, soluble only with difficultyin dilute acids are readily attacked in the presence of hydrogenperoxide.64 The end-point of the reaction between mercurousnitrate and potassium bromide may be ascertained by Fajam’smethod, sodium alizarinsulphonate being added as the indicator.65Modifications in methods of determining minute quantities ofmercury are described.66Gentle heating of the stannates of sodium and barium in a currentof hydrogen chloride results in quantitative volatilisation of thetin as tetra~hloride.~’ “ Chloramine” may be used instead ofiodine in the titration of stannous chloride provided that theacidity of the solution does not exceed 5%.68 In solutions con-taining hydrochloric acid, the reduction of quinquevalent arsenicby hydrazine in presence of potassium bromide is quantitativeonly when the concentration of acid is high.69 The Gutzeit method59 H.B. Weiser and E. J. Durham, J. Physical Chem., 1928,32, I061 ; A., 944.eo G. Spacu and J. Dick, 2. anal. CJLem., 1928, 73, 279; A., 499.G2 A. D. Petrov, J . Buss. Phys. Chem. SOC., 1925, 60, 311; A,, 726.Idem, ibid., 1927, 72, 289; A., 1928, 264.I. N. Holthoff and G.H. P. v. d. Meene, 2. a n d . Chenz., 1927, 72, 337;A., 1928, 265.64 A. S . Komarovsky, ibid., p. 293; A., 1928, 268.6 5 R. Burstein, Z. anoig. Chem., 1928, 325; A.,.265.G6 A. Stock and W. Zimmermann, 2. angew. Chern., 1928, 41, 546; A., 726;N. E. Schreiber, T. Sollmann, and H. W. Booth, J . Amer. Chew. SOC., 1928,50, 1620; A., 860.F , i G. Jander and F. Busch, Ber., 1927, 60, [BJ, 2694; A., 1928, 146.E. Rupp, Z. anal. Chem., 1928, 73, 5 1 ; A., 387.t r Y H. Kubina and J. Plichfa., ibid., 74, 235; A., 1928, 972ANALYTICAL CHEMISTRY. 205€or the determination of arsenic has been the subject of a numberof papersY7O as also has the titration of arsenious acid with per-manganate.71 Small amounts of arsenic, after conversion into nearlyneutral arsenate, are determined nephelometrically with a reagentcontaining cocaine and molybdic acid.72In sufficiently acid solutions, quinquevalent arsenic and antimonyare completely reduced by hydriodic acid to the tervalent state,but the liberated iodine cannot be directly titrated in air; themethod of utilising this reaction for quantitative work is described.73From a faintly ammoniacal solution of arsenate and antimonatecontaining fluoride, silver nitrate quantitatively precipitates thearsenate, free from antimony.74 In a scheme for the quantitativeseparation of arsenic, antimony, and tin, the neutralised solutionof the thio-salts, as usually obtained, is oxidised with hydrogenperoxide ; hydrogen sulphide now precipitates from weakly acidsolution only tin and antim0ny.~5 Ceric sulphate solution hasbeen applied to the volumetric determination of antimony in thepresence of arsenic, which may then be titrated with br~rnate.'~The application of membrane methods of filtration in the deter-mination of antimony as tetroxide has been studied,77 and also acolorimetric process for small quantities, following, if necessary,a separation from tin by deposition on copper.'*Aluminium hydroxide, precipitated by warming a solution ofan aluminium salt with potassium cyanate, is obtained in a lessgelatinous condition than usual, becoming granular on subsequentboiling.79 The colorimetric determination of aluminium withvarious reagents has been investigated-sodium alizarinsulphon-ate,80 ammonium aurintricarboxylate,81 and 1 : 2 : 5 : 8-tetrahydr-70 H.Heidenhain, J. Assoc. 03. Agric. Chern., 1928,11, 107; A,, 384; A. P,Lerrigo, Analyst, 1928, 53, 90; A., 263; C. H. Cribb, ibid., 1927, 52, 701;B., 1928, 89; J. White, ibid., p. 700; B., 1928, 89; J. R. Stubbs, ibid., p. 699;B., 1928, 89; A. S. Dodd, ibid., 1928, 53, 162; A,, 498.71 N. Kanb, Sci. Rep. Thhoku I m p . Univ., 1927, 16, 873; A., 1928, 264;F. G. Germuth, Amer. J. Pharrn., 1927, $9, 751; A., 1928, 263.72 H. Kleinmann, Deut. Z. ges. geiichtl. J4ecl., 1927, 11, 61; A,, 1028,858.73 P. E. IVinkler, Helu. ChinL. Acta, 1927, 10, 837; Bzrll. Soc. cJ&n. Be@.,1927, 36, 491; A., 1927, 1160; K. Pedersen-Rjergnard, Dansk Tidsskr.Pam., 1928, 2, 1 ; A., 144.74 L. W. McCay, J.drner. C'hein. Soc., 1928, 50, 368; A., 384.7 s A. Thiirmer, Z. anal. Chenh., 1928, 73, 196; A., 498.7 G H. Rathsburg, Bcr., 1928, 61, [B], 1663; A., 1207.i 7 A. Simon and W. Neth, Z. nrial. Chem., 1927, 72, 307; A., 192S, 265.i 8 S. G. Clarke, Analyat, 1928, 53, 373; A,, 983.79 R. Ripan, Bul. SOC. Xtiinte Cluj, 1927, 3, 311 ; A,, 1928, 499.w J. H. Yoe and W. L. Hill, J. Amel.. Chem. SOC., 1928, 50, 748; A., 500.81 Idem, ibid., 1927, 49, 2395; A,, 1927, 1161206 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.oxyanthraquinone.82 Iron and aluminium phosphates are precipit-ated a t pH 5.0-5.4, whilst calcium phosphate is not precipitatedbelow pH 6.5. This separation is effected practically by adding anexcess of ammonium acetate to the solution, slightly acid to thymol-blue.83 Considerable occlusion of chromate occurs when aluminiumand iron are precipitated as hydroxides from solutions containingchromate, although no chromate is occluded when these metals areprecipitated as phosphates.a In the presence of sulphates, alumin-ium and nickel may be separated by the use of fusible white pre-~ i p i t a t e . ~ ~ The oxide content of aluminium alloys can be deter-mined by volatilisation a t 275", in a current of dry hydrogenchloride.86 A volumetric process for determining aluminiumdepends on the formation of the complex oxalate Al(C,0J3K3which is neutral to methyl-red.87Improvements have been made in the determination of ferrousiron in silicate rocks by means of hydrofluoric and sulphuric acids,hard-glass vessels being used.88 The usual iodate procedure hasbeen applied to the titration of ferrous ir0n.8~ Iron, aluminium,chromium, and titanium are precipitated as hydroxides from boilingsolutions of their salts by hexamethylenetetramine in the presenceof ammonium salts.Manganese, zinc, cobalt, and nickel are notprecipitated under these conditions, thus permitting a separationof iron from these metals. Chromium, however, cannot be separ-ated by this means.g0 The fading caused by the presence ofphosphates in the colorimetric determination of titanium by meansof hydrogen peroxide may be prevented by the addition of uraniumacetate solution under certain condition~.~l Knop's method fortitrating iron is applied to micro-analysis, a O.004N-dichromatesolution being used; the same end-point is obtained potentio-metrically and by using diphenylamine as an internal indicator.92A method for the micro-determination of zinc is outlined, whereinthe excess of ferrocyanide is determined by observation of thetime required for the development of the blue colour when 0.05 mg.82 I. M.Kolthoff, J. Amer. Pharm. Assoc., 1928, 17, 360; A., 608.83 A. J . Fatten and 0. B. Winter, J. dssoc. Off. Agric. Chenb., 1928, 11, 202;A., 727.K. K. Jiirvinen, 2. anal. Chem., 1928, 75, 1; A,, 1206.85 B. Aolaja, Arhiv Hemiju Farm., 1928, 2, 136; A., 860.8 8 G. Jander and W. Brosse, 2. angew. Chem., 1928, 41, 702; A,, 860.87 A. WGhlk, Dan8k Tidaskr. Farm., 1927, 1, 625; A., 1928, 38; compareF.Feigl and G. Krauss, Ber., 1925, 58, [ B ] , 398; A., 1925, ii, 329.B. A. Soule, J . Amer. Chem. Soc., 1928, 50, 1691; A., 861.G. B. Heisig, ibid., p. 1687; A., 1928, 861.P. RBy and A. K. Chattopadhya, 2. ccnorg. Chem., 1928,169,99; A,, 387. '' F. G. Germuth, J . Amer. Chern. SOC., 1928, 50, 1910; A., 982.92 A. Uenedetti-Pichler, 2. and. Chem., 1928, 73, 200; A., 600ANALYTICAL CHEMISTRY. 207of iron is added to 5 C.C. of the supernatant liquid.93 The use ofstock ammonium sulphide solution, even freshly prepared, isdeprecated on account either of partial precipitation of alkaline-earth metals or of formation of colloidal nickel sulphide. Thesedifficulties are avoided by the passage of hydrogen sulphide intoan ammoniacal solution.94 For the quantitative precipitation ofmanganese by means of thiocyanate and pyridine, a large excess ofpyridine is needed ; the complex, Mn(SCN)&C,H,N, may beweighed as S U C ~ .~ ~ The analogous zinc complex may be treated~imilarly.~6 By using nitric acid (d 1.332) and carrying out theprecipitation with potassium chlorate on a water-bath, manganesein any concentration can be determined ac~urately.~~A scheme for the separation, qualitative or quantitative, ofcalcium, barium, and strontium involves the removal of calciumfirst as the double potassium ferrocyanide, barium being thenprecipitated as chromate in the usual manner.98 In a micro-chemical method for the determination of calcium, this metal isprecipitated in presence of 4 vols. of alcohol as the hydrated sulphateand weighed in this form.99 The permanganate method for calciumand the chromate method for barium have been applied on theinicro-scale; in the latter case it is necessary to determine theexcess of chromate added.l Silver and barium chromates formsolid solutions with each other so that it is impossible to precipitatethem successively by means of chromates; an approximate suc-cessive precipitation, however, occurs in 45% Calciumoxide, obtained by ignition of the oxalate a t 1000" in an electricmuffle, is cooled best in a desiccator over well-burnt lime.3The pyrophosphate method for the determination of magnesiumcontinues to attract attention ; a second precipitation underspecified conditions is essential and a third may be ne~essary.~g3 R.Nakaseko, Mem. ColE. Sci. KyBtb, 1928, A , 11, 95; A,, 725.94 J. Rdl, 2. anal. Chem., 1927, 72, 298; A., 1928, 263.95 G. Spacu and J. Dick, ibid., 1928, 74, 188; A., 982.96 Idem, ibid., 73, 356; A,, 1928, 608.9' M. Marqueyrol and L. Toquet, Ann. C'him. anal., 1927, (ii), 9, 289, 324;A., 1927, 1162; 1928, 38.~313 0. Macchia, Notiz. chime-ind., 1927, 2, 311; A., 1928, 385; Chem.-Ztg.,1928, 52, 281; A., 498.g9 F. Rogozinski, Rocz. Chem., 1928, 8, 276; A., 1108; Bull. SOC. chim.,1928, (iv), 43, 464; A., 980.W. Geilmann and R. Holtje, 2. anorg. Chern., 1927, 167, 128; A,, 192i,1159.A. Mazzucchelli and B. Romani, Gazzetta, 1927, 57, 900; A., 1928, 264.A. Franks and R. Dworzak, 2. anal. Chem., 1927,72, 129; A., 1927,1166.J. Majdel, Arhiv Hemiju Farm., 1927, 1, 216; A., 1928, 38.(Miss) A .MT. Epperson, J . Arner. Chem. L%C., 1928, 50, 321 : A., 386208 ANNUATA REPORTS ON THE PROGRESS OF CHEMISTRY.A rapid alkalimetric method for the determination of magnesiumhas been described6 and also the use of tropzeolin-00 in a colorimetricprocess.Uranyl zinc acetate may be used in the gravimetric determin-ation of sodium in the absence of lithium, strontium, phosphate,and large amounts of oxalate and tartrate; barium, calcium,magnesium, and zinc do not interfere. Subsequent treatment ofthe precipitate with ferrocyanide serves for the basis of a micro-method applicable to biological materiaLQ Further work has alsoappeared on the use of the corresponding magnesium reagent .loDihydroxytartaric acid can only be used for the quantitativedetermination of sodium by working a t 0" and introducing a cor-rection for the solubility of the sodium salt.ll Various modificationsof the cobaltinitrite process for potassium have been made; treat-ment of the washed precipitate with acid ferrous sulphate solutionliberates nitric oxide which may be measured.12 An iodometricprocess for treating the cobaltinitrite precipitate serves formicro-determination.13 Modifications of the tartrate-cobaltinitritemethod have been made to obtain stoicheiometric results.14 Twoother papers deal with the chloroplatinate l5 and the perchlorateprocess.16The use of strontium chloride, admixed with ammonium chloride,has been studied for fusion with silicates in the determination ofalkali metals therein.17 8-Hydroxyquinoline is used for the pre-cipitation and determination of aluminium and magnesium incertain silicates; the reagent is also useful in removing thesemetals prior to alkali determination.l86 L. Galimberti andE. Zoccheddu, Ann. C'him. Appl., 1928,18,286; A., 980.7 J. ZahradniBek, Biochem. Z., 1927, 191, 61; A., 1928, 145.8 H. H. Barber and I. M. Kolthoff, J. Amer. CJbena. Soc., 1928, 50, 1625;A,, 859.9 €1, K. Barrenschcen and L. Messiner, Biochem. Z., 1927, 189, 308; A.,1928, 96.10 E. di Benedetto and A. D. Marenzi, Rev. C'entr. Estud. Pawn. Biopuim.,1927, 16, 592; A., 1928, 1205; A. Nau, Bull. Xoc. Pharm. Bordeaux, 1927, 65,67; A., 1928, 385; Weiland, Mitt.Kali-Forsch.-Anst., 1927, 21; A., 1928, 385.11 A. P. Okatov. J. Ru8s. Phys. Chem. Soc., 1928, 60, 661; A., 979.13 G. Jandsr and H. Faber, 2. anorg. CJt,em.. 1928, 173, 225; A., 980.13 A. Leulier, L. Velluz, and H. Griffon, Ball. SOC. Chim. biol., 1928, 10, S91;1 4 M. Wikul, %. and. Clwm., 1927, 72, 346; A., 1928, 264; compere 2.l5 M. McCurdy, Proc. Nova Scotian Inst. Sci., 1927, 18, 142 J A., 1928, 859.l6 A. T. Dalsgaard, Dan8k Tidash. Fawn., 1925, 2, 257; A., 1205.l7 5. Kevina, Chem. L&y, 1928, 22, 267; A., 859.l8 J. Robitschek, Chem. Obxor., 1927, 2, 325; J . Amer. Ceram. SOC., 1928,A., 1205.anorg. Chem., 1926, 151, 338; A., 1926, 491.11, 687; B., 895ANALYTICAL CHEMISTRY. 209Fusion with bismuth in place of lead usually effects a saving oftime in the separation of iridium and rhodium.lg The addition ofpotassium iodide to solutions of these two metals precipitates therhodium as iodide.20 Schemes for the analysis of iridiurn2l andfor separating the various platinum metals are described.22 Plati-num, palladium, and rhodium, but not osmium and ruthenium,form insoluble complex compounds on addition of thiocyanate ;iridium gives an unsuitable pre~ipitate.2~ The coloration givenwith potassium iodide may be utilised €or rapid determination ofpalladium in platinum.24 Osmium tetroxide is distilled from achromic acid mixture, tlhe sulphicle being then precipitated andignited to metal.25 -Thorium is completely precipitated its subphosphate,ThP206,1 1H,O,from boiling solutions containing 10% of hydrochloric acid ; asubsequent precipitation as oxalate must be made, as conversioninto pyrophosphate by ignition is not quantitative.26 In theabsence of mannifol, glycerol, or dextrose, only about 4004 ofgermanic acid is neutralised by caustic soda, with phenolphthaleinas indicator.The mannitol complex liberates iodine from iodide-iodate s0lution.~7 The important separation of iron from galliummay be effected by means of wnitroso-p-naphthol ; 28 aluminiumand also ferric iron may be separated from beryllium by precipit-ation with 8-hyclroxyquinoline in acetic acid solution.29 The useof curcumin in colorimetric determination of beryllium has beendescribed.30 Conflicting views exist as to the value of 1 : 2 : 5 : 8-tetrahydroxyanthrayuinone for this purpose.31 Precipitation ofberyllium with ammonia gives low results; the use of ammoniumnitrite is satisfactory if boiling is effected in presence of methylalcohol in order to volatilise methyl nitrite.The pyrophosphatemet'hod is described and also a number of separations by means oft annic acid.32 Pnrbher iiivesfigatioiis of the analytical chemistryB. Karpov, Ann. Inst. Platine, 1928, 6, 98; A., 983.V. V. Lebedinski, ibid., 1927, 5, 364; A., 1928, 728.31 0. E . Zvjsgintsev, ibid., p. 189; A,, 1928, 728.22 Anon., Chem Eng. Min. Rev., 1928, 20, 142, 170; A,, S61.z3 V. N. Ivanov, Ann. Inst. Platine, 1926, 4, 331; A., 1027, 1162.24 0. E . Zvjagintsev, ibid., p. 364; A,, 1927, 1162.26 F. Hecht, 2. anal. Chem., 1928, 75, 28; A., 1206.z 7 A.Tchakirian, Compt. vend., 1928, 187, 229; A., 983.2 8 J. Papish and L. E. Hoag, J. Amer. Chem. SOC., 1928, 50, 2118; A., 981.29 I. M. Kolthoff and E. B. Sandell, ibid., p . 1900; A., 981.3O I. &I. Kolthoff, ibid., p. 393; A., 386.31 Idem, ibid.; H. Fischer, 2. anal. Chem., 1928, 73, 5 4 ; A., 385.32 L. Moser and J. Singer, Monatsh., 1927, 48, 673; A., 1928, 145.E. Fritzmann, ibid., 1928,6, 116; 2. anorg. Chem., 1928,169,366; A., 388210 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.of tantalum, niobium, and their mineral associates are de~cribed.~~Examination has been made of various gravimetric metho& ofdetermining molybdenum ; conversion of the sulphide into trioxideis preferred.34Tungstic acid may be separated from a freshly precipitatedmixture with metastannic acid or from a mixture with silica dehydr-ated a t 130" by treatment with sodium tungstate solution undersuitable condition^.^^ Volatilisation in hydrogen chloride has beenapplied to the analysis of sodium and barium t~ngstates.~6 Asomewhat arbitrary iodometric method for the determination ofsmall quantities of thallium has been workedOn account of the readiness with which dry h y d r a ~ e hydrogenselenate explodes in contact with hydrogen chloride vapour, selen-ates should be reduced t.0 selenites by hydrochloric acid beforehydrazine hydrate is added to complete the reduction.38 Thereduction of selenious acid by hydriodic acid for analytical purposesis best effected in presence of carbon disulpliide ; otherwise part ofthe iodine liberated is adsorbed in the precipitated selenium.39When iodine is run into sulphite solution low results occur andthese are attributed less to oxidation than to volatilisation whichis rendered easier by the increasing acidity due to the hydriodicacid formed.A study has also been made of the oxidation ofsulphites by air, having in view the possibilities of losses in analyticalprocesses for determining sulphurous acid involving distillati~n.~~The high results obtained when barium sulphate is precipitated inpresence of chromate can be diminished by reduction of the chrom-ate, but it is preferable that all the chromium should be removedfir~t.~1 The conditions under which the precipitation of sulphuricacid as barium sulphate takes place from solutions containingantimony, tartaric acid, and hydrochloric acid (e.g., in the analysisof antimony sulphide) have been investigated with the view ofobtaining reproducible results, independent of the concentrationof antimony and with minimal corre~tions.~2A series of tests has been carried out to check the solubility of33 W.R. Schoeller and A. R. Powell, Analyst, 1928,53,288; A., 608 ; W. R.Schoeller and E. F. Waterhouse, ibid., pp. 467, 516; A., 1207; I. Wada andS. Kato, Sci. Paper8 Inst. Phy8. Chem. Res. Tokyo, 1927,8,227; A., 1827,1162.34 E. Wendehorst, 2. anal. Chem., 1928, 73, 453; A,, 861.35 J. Ciochina, ibid., 72, 429; A., 387.36 G. Jander and D. Mojert, 2. anorg. Chem., 1928, 175, 270; A., 1206.37 S.Proszt, 2. anal. Chem., 1928, 73, 401; A., 726.313 J. Meyer and W. Aulich, Ber., 1928, 61, [BJ, 1839; A., 1200.n9 R. Berg and M. Teitelbaum, Chem.-Ztg., 1928, 52, 142; A,, 383.41) H. M. Mason and G . Walsh, Analyst, 1928, 53, 142; A., 497.d l M. N. Pavlov, Ukraine Chem. J . , 1926,2, 353; A., 1927, 1160.42. S. von Finbly, 27. and. Chem., 1928, 75, 17; A., 1204ANALYTICAL CHEMISTRY. 21 1barium sulphate in various concentrations of acid; the resultspoint to the need for systematic investigation of all the conditionsfor the determination of very small amounts of ~ulphate.*~ Ifconcentrated solutions of sulphate are treated with concentratedbarium chloride solution, and the liquid is then diluted and heatedfor some time, barium sulphate may be obtained in a coarse granularform which does not adsorb other salts from the solution.44 Someobservations have been made on the sources of error of the benz-idine method for the determination of sulphates,45 whilst a colori-metric micro-method is based on a preliminary precipitation ofbenzidine ~ u l p h a t e .~ ~ In the direct iodometric determination ofpersdphate, potassium chloride 47 and ammonium chloride act asaccelerators of the reaction ; 48 some indirect methods are alsode~cribecl.~~ All polythionates, except dithionate, are oxidised com-pletely to sulphate by heating with iodine in bicarbonate solutionunder appropriate conditions. Trithionates are oxidised at theboiling temperature by copper sulphate ; tetrathionate, thio-sulphate, and sulphite, but not pentathionate, interfere.49The microchemical determination of phosphoric acid as strychninephosphomolybdate has been investigated ; 50 when washed with10 yo nitric acid, the precipitate has a composition correspondingwith the formula llMo0,,H,P04,(Str),,ZHN03.51 The orangecolour given by sodium salicylate with uranyl acetate is utilisedfor the volumetric determination of phosphate.52 Zinc and cadmiumamalgams reduce sexavalent molybdenum quantitatively to thetervalent state, and this reduction has been applied to the deter-mination of phosphates, following precipitation as ammoniumph~sphornolybdate.~~ This compound can be titrated directly inammoniacal solution in the presence of acetor~e.~~ The state-ment 55 that the blue coloration obtained in the usual Denig6s43 H.R. Jensen, Analyst, 1928, 53, 136; A., 49i.44 V. Njegovan and V. Marjanovii., Z. a d . CJmn., 1928, 73, 271; 74, 191;45 0. Nydegger, Chem-Ztg., 1928, 52, 318; A., 607.r16 J. Yamazaki, Bull. Chm. SOC. Japan, 1928, 3, 173; A., 1107.4 7 L. von Zombory, 2. anal. Chern., 1928, 73, 217; A,, 497.4 8 A. Schwicker, ibbid., 74, 433; A,, 1928, 1107.40 E. H. Riesenfeld and G. Sydow, 2. aporg. C'JLeni., 1928,175, 74; A., 1201.5o C. Antoniani and R. B. Jona, Qiorn. Chiin. I n d . Appl., 1928, 10, 203; A.,G1 C. Antoniani, ibid., p. 408; A., 1265.62 L. Duparc and E. Rogovine, Helv. Chim. Acta, 1928, 11, 598; A,, 979.A., 497, 978.979.K. Someya, 2. azzorg. Chem., 1928, 175, 347; A., 1204; S.Hakomori,64 G. Hammarsten, Compt. rend. Trav. Lab. Corkberg, 1928, 17, No. 5, 1 ;65 V. V. Ciurea, Bul. Soc. Chim. Romtinia, 1927, 9, 86; A., 1928, 384.Sci. Rep. TGholcu Imp. Univ., 1927,16, 719; A,, 1927, 1160.A, 263212 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.colorimetric process is quantitatively discharged by chlorinewater is challenged. 57 The methods of precipitating magnesiumammonium phosphate in the presence and absence of ammoniumacetate have been compared; 58 in the absence of molybdate ions,the acetate method more readily produces a crystalline precipitate.Conditions for the iodometric determination of phosphites aredescribed.59With suitable precautions, nitrates may be determined by reduc-tion to nitrites by ferrous sulphate in concentrated sulphuric acidsolution, the end-point being shown by the coloration due to thecompound of ferrous sulphate with nitric oxide; the effect ofhalogens and metals on the process is given.60 Reaction betweenazides and iodine, induced by sulphides and thiosulphate (videsupra) is also promoted by carbon disulphide, especially whenalcohol or acetone is present ; a volumetric process for the iodo-metric determination of azides is based on this action.61A discrepancy is recorded in the strength of the picric acid solu-tion used as an artificial standard in a colorimetric process fordetermining silica.62Small quantities of free chlorine, e.g., in tap-water, may bedetermined c olorime t ricall y with us - dimet h yl -p - phenylenediamine ,the water being brought to a definite acidity and the colour matchedwith standard solution of methyl-red; 63 the pink colour is alsogiven by other mild oxidising agents, e.g., iodine or ferric chloride.The addition of concentrated zinc sulphate solution greatly increasesthe sensitiveness of the methylene-blue perchlora>te coloration ;the colour given by chlorates must be neutralised by means ofsodium nitrate.64 For the purpose of determining perchlorate inpresence of large amounts of chlorate, the latter may be reducedto chloride by means of sulphur dioxide; after removal of theexcess of reducing agent, the perchlorate is determined by means56 Compare G.DenigAs, Cornpt. rend., 1928, 186, 318; A., 263.57 I. Voicu, Bzil.SOC. Chim. Rorncinia, 1928, 10, 50; A., 979.58 W. M. McNabb, J . Ames.. Chem. SOC., 1928, 50, 300; A., 384.59 P. Car&, Cornpt. rend., 1928, 186, 436; A,, 384.6o L. SzebellBdy, 2. anal. Chern., 1928, 7’3, 145; 74, 232; A., 498,61 F. Feigl and E. Chasgdl, ibid., 74, 376; A,, 1106.979.E. J. King and C. C. Lucas, J . Arner. Chem. Soc., 1928, 50,2395; A,, 1205.Compare F. Dibnert and F. Wandenbulcke, Compt. rend., 1923,176,1878; A . ,1923, ii, 507.63 K. Alfthan, PinsEa Kemistamundets Medd., 1927, 36, 109; J . Amer.Water Work8 ASSOC., 1928, 20, 409; B., 838. Compare I. M. Kolthoff, Clbem.Weekblad, 1926, 23, 203; B., 1926, 517.64 0. S. Fedorova, J . Rm8. Phys. Chem. SOC., 1027, 59, 509; A,, 1927,1169ANALYTICAL CHEMISTRY. 213of titanous chloride.65 An indirect bromometric process for thedetermination of chlorates is described ; 66 perchlorates are reducedby refluxing with titanic and cadmium sulphates in the presence ofzinc and iron powders, the chlorides being then determined volu-metrically.67 Further work is recorded on the determination ofminute quantities of iodine.68 The use of membrane filters fordetermining fluorine as calcium fluoride is described ; 69 the filtrationis much more rapid in the presence of nitrate ions.Sources of error in the determination of carbonic acid by pre-cipitation as barium carbonate and titration of the excess of alkaliare pointed 0 ~ t .7 0 A volumetric process for the determination ofsmall amounts of carbonic acid and free ammonia present in distilledwater is described, together with the corrections which must beapplied.sl The direct oxidation of cyanide by means of per-manganate in strongly alkaline solution is greatly accelerated bythe addition of copper sulphate ; this process for determining alkalicyanides depends on immediate conversion of the permanganatein Oo manganate .i2Organic Analysis.Qualitative.-Some further mercury alkyl and aryl halides havebeen prepared for the purpose of identifying the halides.73 TheGrignard reagents from certain tertiary aliphatic halides givepositive results in the colorimetric test previously described 74provided that 5 minutes be allowed for the reaction with theMichler's ketone.75 Small quantities of organo-magnesium halidesmay be rapidly identified by crystalline derivatives prepared froma-naphthylcarbimide. 76 Some colour and microchemical reactionsof the following substances are described : rnannit01,~~ atr~pine,'~6 s E.SpitaIski and S. Jofa, J . Rum. Phys. Chem. SOC.. 1928, 60, 75;66 K. Peters and E. Deutschliinder, Apoth.-Ztg., 1926,41, 594; A., 1928,383.G7 E. S . Tomula, Ann. Acad. Sci. Pennicae, 1927, A , 29, No. 21; A., 1928,263.P. A. Meerburg, %. physikat. Chein., 1927, 130, 105; A,, 1927, 1160;J. F. McClendon, J . Amer. Chem. SOC., 1928,50, 1093; A., 607; L. S. van derVlugt, Chem. WeeBlad, 1928, 25, 196; A., 497.i o J. Lindner, 2. anal. Chem., 1927, 73, 135; A., 1927, 1161.i 1 S. Bjerrum, Ann. Acad. Sci. Penizicoe, 1927, A , 29, KO. 1; A., 1928, 264.i t H.Gall and G. Lehmaim, Ber., 1925, 61, [B], 670; A., 624.li3 E. L. Hill, J . Amer. Chem. SOC., 1928, 50, 167; A., 269.74 H. Gilman and F. Schulze, ibid., 1925, 47, 2002; A., 1925, ii, 1011.i 5 Idem, Bull. SOC. chim., 1927, (iv), 41, 1479; A., 1928, 160.i 6 33. Gilman and M. Furry, J . Amer. Chem. Soc., 1928, 50, 1214; A., 660.7 7 L. Ekkert, Pharm. Zentr., 1928, 68, 433; A., 1114.Idem, ibid., 69, 529; A., 1145; M. Wagmaar, Phar?:,. TI~~ekblccrl, 1928,Z. anorg. Chem., 1928, 169, 309; A,, 383.G . G. Kandilerov, Bey., 1928, 61, [KJ, 1667; A., 1204.65, 197; A., 532214 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.morphine, 79 cholesterol,s0 ergosterol, hyoscyamine, 82 citric acid,83carb0hydrates,~4 and volatile aldehydes and ketones, such as thosepresent in fruits and essences.85 Vanillin and piperonal behavelike other aldehydes in giving sensitive colour reactions with certainalkaloids.86 Some aldehydes give colour reactions with lecithinand sulphuric acid.*’ A sensitive differentiation of phthalic andterephthalic acids depends on the rate of precipitation of complexcompounds with pyridine and copper or cobalt salts.88 Methodsfor the micro-identification of the three xylenes in admixture aredescribed.89Quantitative.-Oxidation with permanganic anhydride is appliedto the determination of organic carbon in soil and in pure organiccompounds.gO The baryta method for determining carbon dioxideis applied to organic analysis, t,he excess of barium hydroxide beingtitrated and the precipitated barium carbonate being convertedinto and weighed as ~ulphate.~l An apparatus far the determin-ation of carbon and hydrogen without tho use of catalysts is de-scribed, in which combustion takes place in a current of pureoxygen.92 Some notes on the rapid determination of carbon andhydrogen in organic compounds are recorded.93 Pregl’s “ universalfilling” has been successfully applied on a macro-scale,0* andvarious observations have been made with regard to micro-analyticalmethods for carbon and hydrogen.95 By combustion in a closedapparatus with a measured volume of oxygen, the approximateoxygen content of organic compounds is obtained, the d u e s being79 L.Ekkert, P h r m . Zentr., 1928,69, 198; A., 533; M. Wagenaar, Phami.L.Ekkert, Pharm. Zentr., 1928, 69, 97; A,, 410.TYeekbZad, 1927, 64, 1119; A., 1927, 1210.81 Idem, ibid., p. 276; A., 1928, 1000.82 M. Wagenaar, P b m . Weelcblad, 1928, 65, 549; A,, 1030.88 Idem, ibid., 1927, 64, 1135; A., 1927, 1213.84 L. Ekkert, Pham. Zentr., 1928, 69, 597; A., 1220; S. Y . Wong, ChineseJ . Physhl., 1928, 2, 255; A., 1219.C. Griebel and F. Weiss, Mikrochem., 1927, 5, 146; A., 1928, 82.*6 L. van Itallie and A. J. Steenhauer, Arch. Pham., 1927, 265, 696; A.,87 D. Migliacci, Boll. Chim. farm., 1928, 67, 324; A,, 1043.88 R. Ripan, Bul. 806. Stiinte Cluj, 1927, 3, 30s; A,, 1928, 1006.89 M. Magita, Bull. Chem. SOC. Japan, 1928, 3, 191 ; A., 1234.*l P. Dickens, Chem. Fc~br., 1928, 293; A,, 784.92 I. Marek, Arhiv Hemiju Farm., 1927,1, 188; Bull.Soc. chim., 1928, (iv) ,93 E. Berl, A. Schmidt, and K. Winnaoker, Ber., 1928, [BJ, 83; A., 312.94 W. Davies, J., 1927, 3161; A., 1928, 190.95 H. D. K. Drew and C. R. Porter, J . SOC. Chem. Ind., 1928, 47, 17r; A.,312; B. Bobraliski and E. Sucharda, Rocz. Chem., 1928,8,290; A., 1107; R.Goubau, Natuurwetensch. Tijda., 1928, 10, 129; A., 1205.1928, 311.L. U. De Nardo, Qwrn. Claim. Ind. Appl., 1928,10, 253; A,, 909.43, 910; A., 82ANALYTIC1AL (3HEMISTRY. 215chiefly of service in helping to confirm the presence of thiselement.96Many amino-acids can be titrated in acetone solution withalcoholic hydrochloric acid, benzeneazo-a-naphthylamine beingemployed as indicator.97 In Kjeldahl digestions, the ammonia,up to 20 mg.of nitrogen per 100 c.c., can be determined by directNesslerisation in presence of gum a r a b i ~ . ~ ~ A modified Dumasapparatus is described for the volumetric determination of carbonand nitrogen a t the same time.9Q Possible sources of error in themicro-Dumas method are indicated.lIn a micro-analytical process for sulphur, the organic compoundis volatilised from a platinum boat in a stream of hydrogen, thesulphur being then retained on freshly-reduced pure nickel assulphide.2 The addition of alkali chloride in the Carius methodfor sulphur is recommended for use with difficultly oxidisablesubstances.3 Determinations of the effect of time and temperatureon Pregl’s rnicro-Cariux method have been made with various typesof compounds.4 A volumetric process for determining seleniumin halogen-free compounds is described .5Treatment in alcoholic solution with sodium, followed by hydrogenperoxide, affords a method for determining halogens, especiallysuitable for naphthalene derivatives, terpenes, and heterocycliccompounds.6 A modification of Stepanov’s method has been madeto allow the determination of halogens in the benzene nucle~s.~To prevent loss of ammonium halide in ter Meulen’s process forlialogeas, the exit gases are passed over strongly heated bariumcarbonate; in certain cases the use of a hydrogenating catalyst isnecessary.8Organo-lead compounds in which the metal is directly attached toaryl groups are arzalysed by oxidation by means of nitric-sulphuricA,, 636.rend.Tiac. Lab. Carhberg, 1927, 17, No. 4, 1 ; A., 1928, 313.s6 G. G. Glockler and L. D. Roberts, J . Amer. Chern. SOC., 1928, 50, 828;97 K. Linderstrsm-Lang, Z . physw1. Chem., 1928, 1’93, 32; A., 536; Conapt.sa H. M. Chiles, J . dmer. Chem. Soc., 1928, 50, 217; A., 312.R. Vandoni and 111. Algrain, Bull. SOC. chim., 1928, (iv), 43, 265; A., 436.B. Bock and K. Beaucourt, Mikrochem., 1928, 6, 69; A., 978.S. Hanai, BUG. Inst. Phys. Chem. Res. Pokyo, 1928, 7, 915; A., 1267;B. Kubota and S . Hanai, Bull. Chem. SOC. Japan, 1928, 3, 168; A., 1106.V. C. Rogers and G. Dougherty, J . Amer. Chern. SOC., 1928, 50, 1231; A.,660.L. Bermejo y Vida, Chim. et Ind., 1925, 20, 221; A,, 1106.W. E. Bradt and R. E. Lyons, Proc. Indiana Acad. Sci., 1926, 36, 195;M .Proner, Row. Pam., 1926, 4, 99; A., 1928, 436.G. Pawel and Bucher, Ann. Chim. and., 1927, (ii), 9, 321; A,, 1928, 52.H. tcr Meulen, Rec. trav. chim., 1928, 47, 69s; A., 724.A,, 1928, 436216 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.acid.9 The small loss of mercury that occurs when organic mercurialsare so treated introduces a serious error in micro-analysis; goodresults are obtained by heating with fuming nitric acid in a sealedtube.1°The ability of methylglyoxal to form iodoform is used as a basisfor its determinatiomll The -CH2*OH group in ethylene chloro-hydrin is completely oxiciised to >C:O by warming with diazo-benzenesulphonic acid, and a colorimetric process is based on thisreaction.12 Volumetric methods of determining carbamide dependon the oxidation of the dixanthyl derivative by permanganate,l3or by dichr0mate.1~ The tetrapropylammonium ion is quantif-atively precipitated under specified conditions as the diammino-chrornithio~yanate.~~ Some investigations on the analysis ofmixtures of ethyl alcohol, ethyl acetate, acetic acid, and waterhave been rnade.l6 The addition of a small proportion of acetylchloride to the acetic anhydride before mixing with pyridine givessatisfactory results with primary alcohols and most secondaryalcohols. l7 Some organic sulphides are quantitatively oxidisedto sulphones by perbenzoic acid, the excess of oxidant beingascertained iodometrically.18A series of amino-acids and dipeptides has been titrated wit1hacid and alkali, thymol-blue and alizarin-yellow being used asindi~at0rs.l~ A method is described for the determination ofphenylalanine by oxidation to benzoic acid (average conversion,95.2%) by dichromafe.20 Tannic acid may be determined by pre-cipitation at 40-50" with a measured excess of titanium chloride ;interference of gallic, salicylic, mandelic, and other hydroxy-acidsis avoided by working in solutions containing hydrochloric acidwithin certain limits.21The formation of insoluble ferric salts by most sulphinic acids isutilised for determination both of the acids and of the ferric ion.22Sulphinic acids react quantitatively with iodide-iodate solution,H.Gilman and J. Robinson, J . Amer. Chem. Xoc., 1928, 50, 1714; A,,1041. lo A. Verdino, Mikrochem., 1928, 6, 5 ; A., 386.l1 F.Fischler and R. Boettner, 2. anal. Chem., 1928, 74, 28; A., 870.l2 M. B. Sapadinski, ibid., 273; J . Rum. Pi~ys. Chenz. Soc., 1925, 60, 095;A., 989.J. M. Luck, J . Biol. Cheita., 1928, '79, 211; A., 1229.I4 H. Cordebard, Bull. Soc. Chim. biol., 1928, 10, 461; A., 661.l5 F. Rein and F. A. Segitz, 8. and. Chem., 1927,72, 119; A., 1927, 1175.l6 S. Poznmski, J . Amer. Chem. SOC., 1928, 50, 981; Rocz. Chem., 1928, 8,l7 A. Verley, Bull. SOC. chim., 1928, (iv), 43, 469; A., 615.L. N. Lewin, J . pi-. Chem., 1928, (ii), 118, 282; A., 606.l9 K. Felix and H. Miiller, Z. phy8iol. Chena., 1927, 171, 4; A., 1928, 535.G. Kollmrtnn, Biochem. Z., 1928, 194, 1; A., 660.21 S. KtGhnca and N. Ram, Ber., 1928,61, [B], 771; A,, 660.22 8.Krishna and H. Singh, J . Amer. Uhem. SOC., 1928,50, 792; A., 536.152, 229, 263, 272; A., 784ANALYTICAL CHEMISTRY. 217no elimination of the acid group occurring in the nineteen casesexamined.23Dextrose and other reducing sugars may be rapidly and accur-ately titrated with potassium ferricyanide, picric acid being usedas indicator; the procedure employed varies according as thesugar content is relatively large or small.24 A detailed study of theoxidation of dextrose by alkaline copper solutions has been made.25Methods for the quantitative separation and determination ofstrychnine and brucine by means of the hydroferrocyanide aredescribed.26 Strychnine silicotungstate is shown to possess nosimple molecular constitution, although its composition is constsnt :t,he ratio ash : alkaloid is found to be 0.422.27For gravimetric determination of vanillin, precipitation withm-nitrobenzhydrazide is recommended.28 Koppeschaar’s bromin-ation method for phenols and amines is, where applicable, moresatisfactory than direct titration with b r ~ m a t e .~ ~ The colorationgiven by ferric chloride with a number of o-dihydroxybenzenederivatives is applied to their determinati~n.~O The intense redand blue colorations given by 2 : 6- and 2 : 4-&nitrotoluene, respect-ively, with alcoholic sodium hydroxide are applied to the determin-ation of nitrotoluenes in nitr~benzene.~l The amino-nitrogen innitrotoluidines, their acetyl derivatives, and in nitroarsanilic acidis quantitatively obtained as ammonia by refluxing with sodiumhydroxide solution.33 Some notes on the determination of smallquantities of benzoic, cinnamic, and salicylic acid are recorded.33Physical Methods.Furt,her work is recorded on the use of the centrifuge in volu-metric micro-analysis ; 3t details are given for the sulphate-barium 35and for the chromate-lead 36 precipitations.The volume of the23 S. Krishna and B. Das, J . Indian Cl~cn~. Soc., 1927, 4, 367; A,, 1928, 82.24 A. Ionesco-Matiu, Bul. Soc. Chim. Romcinia, 1927, 9, 6 8 ; A., 1928, 398.2 G C. A. Amick, J . Physical Chenz., 1927, 31, 1441; A., 1927, 1213.26 M. Gndreau, J. Phalnz. Chim., 1927, (viii), 6, 145; A., 1928, 314. Com-pare H. I. Cole, Philippine J. Sci., 1923, 23, 97; A . , 1923, ii, 703 ; and W.M.Cumming and D. G. Brown, J . SOC. Chem. Ind., 1928, 47, 8 4 ~ .2 7 E. Stuber and B. Kljatschkina, Arch. Pharm., 1928, 266, 33; A., 532.O 8 J. Pritzkcr and R. Jungkunz, Cltem.-Ztg., 1928, 52, 537; A,, 1009.?@ A. R. Day and W. T. Taggart, Ind. Eng. CJzem., 1928, 20, 545; A., 660.3O H. Xchinalfuss, K. Spitzer, and H. Brandes, Biochenb. Z . , 1927, 189, 226;31 H. Muraour, Bull. SOC. chim., 1928, (iv), 43, 51; A., 279.32 N. Semiganovsky, 2. anal. Ghem., 1927,72,295; A., 1928,314.33 J. R. Nicholls, Amly8t, 1928, 53, 19; A., 313.34 R. F. Lo Guyon, Ann. Chim., 1928, (x), 10, 50; A., 1105.35 Idem, BdL SOC. chim., 1927, (iv), 41, 1387; A., 1928, 36; A. Gunder, 2.36 R. F. Le Guyon and R. F. Auriol, Compt. rend., 1928,186, 1551; A., 860.A., 1927, 1213.See ibid.,p.27; A., 1927, 1062.anal. Chem., 1928, 73, 441; A., 857218 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.precipitate, after centrifuging, may be measured in the ease ofsulphate, calcium, magnesium, phosphate, and potassium ions ;in the first case, the quantity must be not less than 4 mg.37 Theopacity of fine precipitates may be prevented from changing appreci-ably with time by addition of dextrin or gum arabic.38 Furtherextensions have been made in radiometric microanalysis .39The presence, in alcohol, of less than O - O O l ~ o of benzene can bedetermined spectroscopically.40 The application of a polarisationspectrophotometer to colorimetric 41 and nephelometric analysis 42has been investigated, and the photoelectric spectrophotometricmethod, as developed by von Halban, has been extended to themicro-determination of iron and titani~m.~3 A spectral methodis described by which as little as O .O O l ~ o of lead can be detectedand determined in admixture with gold; 44 the method can also beused to discover the location of an impurity in a metal.45 The arcspectrographic detection and determination of gallium 4G and ofgermanium 47 are detailed.Lowe’s interferometer, with distilled water as comparison liquid,is well adapted for use in various types of volumetric analysis.48The nephelometric determination of lead with chromate hasbeen investigated, with particular reference to its application totoxicologicalElectrochemical Methods.Electrolytic.-Minute traces of iodine may be detected by a,nelectrical method, based on depolarisation of the electrode by theiodine, with a consequent increase in current.50A general account has been furnished of the use of the dropping-mercury cathode in electrolytic analysis ; 51 it is possible, by using37 0.Arrhenius and H. Riehm, Medd. K . Vetenskapsakad. Nobel-Inst., 1927,6, No. 14; A., 1928, 1105.38 A. Boutaric and G. Perreau, Rev. gdn. ColZoid., 1928, 6, 113; A., 1108.39 R. Ehrenberg, Biochem. Z . , 1928,197, 467; A., 1105.40 H. Ley and F. Vanheiden, Ber., 1927, 60, [B], 2341; A., 1928, 51.4 1 K. Jebtczyriski and W. Stankiewicz, Rocz. Chem., 1927,7, 549; A., 1928,496. 42 Idem, ibid., p. 534; A,, 1928, 496.43 H. von Helban and E. Zimpelmann, 2. Elektrochem., 1928, 34, 387; A.,1109.44 W.Gerlach and E. Schweitzer, 2. anorg. Chem., 1928, 173, 92; A., 859.45 Idem, ibid., p. 104; A., 860.4 6 J. Papish and D. A. Holt, J . Physical Chem., 1928, 32, 142; A., 265.4 7 J. Papish, F. M. Brewer, and D. A. Holt, J . Amer. Chem. SOC., 1927, 49,4 8 E. Berl and L. Ranis, Ber., 1928, 61, [B], 92; A., 262.4* P. W. Danckwortt and E. Jurgens, Arch. Pharm., 1928,266,374; A., 981.so A. N. Schukarev and Sysoev, J . Rues. Phys. Chem. SOC., 1928, 60, 669;B1 J. Heyrovekf, Bull. SOC. chim., 1927, (iv), 41, 1224; A., 1927, 1159.3028; A., 1928, 146.A., 978ANUY TICAL CHEMISTRY. 219suitable P.D., to determine each of two metals, e.g., bismuth andcadmium, in su~cessioii.~~Conditions for obtaining an adherent deposit of selenium havebeen worked out, electrolysis being carried out in presence ofknown quantities of copper or bismuth.53 A process for theelectrolytic separation of bismuth a t low potential is described.54Reduction of anodic lead peroxide to monoxide by heat is pre-ferred either to weighing as peroxide or to any process of cathodicdeposition.55 The use of fusible alloy electrodes is described indetail for determining copper, zinc, cadmium, mercury, bismuth,and lead, electrolysis being carried out at a temperature at whichthe cathode is fluid, the deposited metal forming an alloy with thefusible metal.Deposition is in most cases effected with Wood'smetal more smoothly than with a mercury cathode.56 Por theelectrolytic determination of zinc in solutions containing sulphuricacid, the preparation of special electrodes is obviated by the additionto the electrolyte of a reducing substance such as alcohol or, better,dextrose.57 An electrolytic apparatus with special electrodes isdescribed for deposition of minute traces of various metals priorto their characterisation by spectrum analysis.5sPotentiometric-The application of acid ceric sulphate solutionas an oxidising agent in potentiometric work has been extensivelyinvestigated, and its use for determining vanadium in steel indicated ;experiments are recorded with nitrites, iodides, oxalic acid, ferro-cyanides, hydrogen peroxide, ferrous iron, arsenic, antimony, tin,titanium, and vanadyl salts. 59 Conversely, cerium salts, afteroxidation if necessary, may be titrated with potassium iodide,sodium nit'ritc, or, preferably, ferrous sulphat e.60 The ceric sulphatesolutions are stable and may be kept for long periods if care is taken.Copper cannot be titrated satisfactorily in aqueous solutionwith potassium, lithium, sodium, or magnesium ferrocyanide,although results may be improved by working in aqueous alcoholic52 E.Ihyle ancl L. Amy, C'ompt. rend., 1928, 186, 1601 ; A,, 857.53 A. Jilek and J. Lukas, Clhem. Listy, 1927, 21, 676; A., 1928, 144.61 Idem, ibid., 641 ; A,, 1928, 146.jii A. V. Pamfilov and A. A. Ulagonravonw, J. Rum. Pliys. C'hem. Soc., 1928,6 6 H. Paweck and R. Weiner, 2. anal. Che?ti., 1927, '72, 225; A,, 1928, 143.5 7 M. Giordani, Ann. Claim. Appl., 1928, 18, 63; A., 490.5 8 E.Buyle ancl L. Amy, Bull. SOC. chim., 1928, (iv), 43, 604; A., 726.59 J. A. Atanasiu, Bul. SOC. Roinane Stiin., 1925, 30, 73; A., 724; J. A.AtanasiuandV. Stefavescu, Ber., 1928,61, [B], 1343; A., 860; N. H. Fuiman,J . Amer. Chem. SOC., 1928, 50, 755, 1675; A,, 409, 860; H. H. Willard and P.Young, ibid., 1322, 1334, 1368, 1372, 1376; Ind. Eng. Chem., 1928, 20, 972;A., 725, 1207.60 K. Someya, 2. anorg. Chem., 1927,168, 56; Sci. Rep. Tdhoku Imp. Univ.,1928,17,93; A., 146; H. H. Willard and P. Young, J . Amer. Chem. Xoc., 1928,50, 1379; A., 725; G. Auti6, Bull. SOC. chim., 1927, (iv), 41, 1635; A., 1928, 38.60, 699; A., 9SO220 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.solutions; 61 in the case of silver, titration with potassium ferro-cyanide gives low results, but with the lithium or sodium salts reason-ably accurate results are obtained.62 Indium chloride can be titratedwith potassium ferrocyanide, the insoluble compound KIn,[Fe(CN),],being presumably formed.63 With gallium chloride, the precipitatehas the composition Ga,[Fe(CN)6]3.64 The same reagent has alsobeen used for lanthanum, cerium, and thorium.65 Rapid methodshave been worked out for the determination of lead and cadmium,66and of silver and zinc 67 when present together, ferrocyanide solutionbeing also used in each case.Uranyl acetate, but not the nitrate,can be titrated with ferrocyanide in 30% alcohol and at 70°.68Yotentiometric measurements involving stannous chloride shouldbe carried out in an atmosphere of nitrogen; the reaction withiodine, ferric iron, chromate, ferricyanide, gold, and platinum isgiven in detail.69 Chromous sulphate is used for the determinationof silver, copper, and gold, alone and together,70 and similarly foriron, copper, and arsenic in sulphuric acid s0lution.7~ The iron-dichromate 72 and iron-permanganate V3 reactions have beenexamined; the principle of the method used in the latter case hasalso been applied to the silver-halogen reaction.74 Chromic acidmay be determined in the presence of vanadic acid by applicationof '' induction " and ~atalysis,7~ and methods for hydrogen peroxideand certain associated per-acids are described.76A method for the analysis of hypophosphoric acid depends onthe very slight solubility of the uranous salt.77 Tellurates andtellurites may be titrated potentiometrically with titanous chloridein the presence of hydrochloric acid ; in sulphuric acid solution, two6 1 E.Miiller and S. Takogami, 2. anal. Clhem., 1928, 73, 284; A., 499; S.Takegami, &id., 74, 39 ; A., .1928, 860.62 W. Speyer, ibid., 74, 108; A., 859.63 U. B. Bray and H. D. Kirschman, J. Amer. Chem. SOC., 1927, 49, 2739;64 H. D. Kirschman and J. B. Ramsey, ibid., 1928, 50, 1632; A., 861.6 5 J. A. Atanasiu, Bul. SOC. Romne Stiin., 1928, 30, 51; A., 726.66 E. Muller and W. Pree, 2. anal. Chem., 1927, 72, 195; A., 1928, 35.6 7 E. Miiller and H. Hentschel, ibid., p. 188; A., 1928, 37.6 8 J. A. Atanasiu, Bul. SOC. Romane Stiin., 1928, 30, 77; A., 727.60 E.Miiller and J. Gijrne, 2. anal. Chem., 1928, '73, 386; A., 727.70 E. Zintl, G. Reinacker, and F. Schloffer, 2. cmorg. Chem., 1927,168, 97 ;7 1 E. Zintl and F. Schloffer, 2. angew. C'hem., 1920, 41, 956; A., 1109.72 F. J. Watson, Chem. Eny. Min. Rev., 1928, 20, 396; A., 1206.73 T. Heczko, 2. anal. Chem., 1928, 73, 404; A., 726.74 ldem, ibid., 74, 289; A., 980.75 R. Lang and J. Swerina, 2. Elektrochem., 1925, 34, 364; A,, 982.7 6 A. Rius, Trans. Amev. Electrochem. SOC., 1928, Sept.; A,, 977.7 7 W. D. Treadwell and G. Schwerzenbach, Hdv. ChLim. Acta, 1928, 11,A., 1928, 38.A., 1928, 146.405; A,, 608ANALYTICAL CHEMISTRY. 221breaks are observed with tellurates, the first being the reductionto tellurous acid, but one only in the case of selenates.ss Detailsare supplied for the determination of hypochlorous and chlorousacids, especially by potentiometric method^,'^ and for the applic-ation of chloramine-T in this class of work.80 The end-point inthe titration of aniline with bromine in neutral solution or withbromate in acid solution is exceedingly sharpys1 as is usually foundfor this titration with other substances.A simple procedure for carrying out certain differential potentio-niehric titrations is described. The method depends on the; changeof potential of an indicator electrode; curves and tables a're sup-plied for use in the process, which is capable of great accuracy forthe determination of univalent ions.82 A similar principle has alsobeen utilised by other ~ o r k e r s . ~ ~The theory of the end-point in acid-alkali titrations has beenconsidered froin the mathematical standpoint). ** A simple andaccurate method is given for finding the point of equivalence inthose cases when the potential curve has only a slight slope nearthe end-point or is unsymrnetri~al.~~Various modifications involving metallic electrodes have beenmade.86 A study of the applicability and possible errors in theuse of the quinhydrone electrode has been made.87 Details of asodium amalgam electrode and of the precautions necessary forits use for measuring sodium-ion concentration are given.ssB. A. ELLIS.J. J. Fox.0. TomiEek, BUZZ. SOC. chim., 1927, (iv), 41, 1389; A., 1928, 36.i 9 E. MiilIer and H. Dietmann, 2. anal. Chem., 1928, 73, 138; A., 497.8o A. McMillan and W. Easton, J . SOC. Chem. Ind., 1927, 46, 4 7 2 ~ ; A,,1928, 144.A. V. Pamfilov and V. E. Kisseleva, 2. anal. Chem., 1927, 72, 100; A.,1927, 1179.B. Cavanagh, J., 1928, 843, 855; A., 607. Compare J . , 1927, 2207;A., 1927, 1045.E3 D. A. MacInnes, 2. physikal. Chem., 1927,130, 217; A., 1928, 36; N. F.Hell, M. A. Jensen, and S. A. Baeckstriim, J . Anzer. Chem. SOC., 1928, 50,2217; A., 977.a4 P. S . Roller, J . Amer. C'hem. SOC., 1928, 50, 1; A., 262; E. D. Eastman,ibid., p. 418; A., 382; F. L. Lfahn, M. Frommor, and R. Schulze, 2. plrysiknl.Chem., 1928, 133, 390; A,, 857.8 5 I. M. Kolthoff, Rec. trav. chim., 1928, 47, 398; A., 496.s8 E. Xiiller and H. Kogert, 2. physikal. Chcm., 1928, 136, 437, 446; A.,1203; PI;. H. Furman, J . Amer. Chem. Soc., 1928, 50, 268, 273; A., 383;X. H. Furman and E. B. Wilson, jun., ibid., p. 277; A., 382; J. 0. Closs andL Kahlenberg, Trans. Amer. Electrochem. SOC., 1928, Sept.; A., 1203.A. Rabinovitsch and V. Kergin, Papers Pure Appl. Chem. Karpov Inst.,Bach Festach~., 1927, 3; A., 1928, 382; 2. Elektrochem., 1928, 34, 311; A.,1106; A. Klit, 2. physikal. Chena., 1927, 131, 61; A., 1928, 143.8 8 G . Ettisch and K. Joechimsohn, 2. EEektrochem., 1928,34,404; A., 1108

ISSN:0365-6217    

DOI:10.1039/AR9282500198

出版商:RSC    

年代:1928

数据来源: RSC

摘要:

BIOCHEMISTRY.THE policy adopted in recent years of reporting on a limited numberof divisions in plant and agricultural chemistry and in animalchemistry has been continued. Since, during the last two or threeyears, subjects of more immediate practical importance have beenreviewed in the section devoted to the chemistry of the plant, itseemed opportune to review this year matters that are at presentof more academic interest. In accordance with this policy therewill be found in this Report a somewhat extensive review of recentprogress in certain fields of protein chemistry. The data uponwhich this part of the Report is based are not exclusively derivedfrom plant chemistry, although it has been prepared by the Reporterresponsible for the plant side. On the other hand, in the case ofcertain subjects (e.g., phosphoric esters formed in yeast ferment-ations), included for convenience of discussion in the animal section,the data drawn upon have been in part derived from what mightlegitimately be regarded as plant chemistry.The space devotedt o protein chemistry in the one section and to the chemical pro-cesses occurring in muscle in the other section necessarily curtailsthe space available for the discussion of less well co-ordinated fieldsof research. Such curtailment is inevitable at times if certainaspects of general biochemistry are to be adequately presented andthe Reporters feel that no apology is needed. Nor do they feel thatany apology is required for the fusion under the agis of one Reporterof fields of cognate interest irrespective of their strict plant oranimal origin.Enzyme Activity of Resting Eacteria.An account was given in the Report for 1926 of Quastel's t'heorythat hydrogenations effected by bacteria are primarily due topolarisations of substrate molecules induced by electric fields whichcharacterise particular centres-the " active centres "-of cellularand intracellular surfaces.Quastel and Wooldridge have furtherinvestigated and developed this theory, and the main results ofthis important study have been recently summarised by the former.2Whether a, particular molecule i~ activated or not at a centredepends upon the nature and strength of the polarising field a tthe centre and upon the nature of the substrate molecule. WhenAnn.Repoyte, 1926, 23, 245. J . Hygiene, 3928, 28, 139BIOCHEMISTRY. 223activation of a substrate molecule (hydrogen donator) occurs, thefollowing equations represent the events which follow : (1) D =i+A,” + ZH’, (2) A, s A, where D is the hydrogen donator, A isthe oxidised form after loss of 2H, and A, is the activated form ofthe molecule which can only exist as such in the presence of thepolarising field. The act of oxidation consists in the transferenceof electrons from A,”, the electrically neutral molecule A, beingtransposed into the normal form A out of contact with the field.The system thus becomes amenable to the same theoretical treat-ment as any system which gives rise to a reduction or oxidationp~tential.~ The developnzent of this hypothesis leads Quastel andWooldridge to consider the specificity and mechanism of enzymeaction.Specificity of action they think depends on three factors :(1) Specificity of adsorption a t the activating centre, (2) the natureand strength of the polarising field at the centre, (3) the con-stitution of the adsorbed molecule.* These conclusions are sub-stantiated by much experimental work with B. coli, which showsthat these active centres or enzymes in the cell surface are not allinactivated under the same conditions, and that they possessspecific differences in their power of adsorbing compounds charac-terised by the possession of a, particular structure. Thus the centres(enzymes) which activate lactic acid as a hydrogen donator adsorbcompounds characterised by -CO*C*OH* or *CH(OH)*C*OH*, whereH* is mobile and the substance acidic, whilst the centres forsnccinic acid adsorb compounds with *C*CH*CO*OH or C*CH,*CO*OHstructures.They consider that the centres of activity of the cellare simply a property of the surface structures of the colloidalmaterials which make up the cell as a whole, and that the actualmagnitude of this structure is of no great significance. It may besmall enough to be classed as “ soluble ” and to pass through itmembrane, or large enough to be classed as “insoluble.” Thedistinction is one of degree, and the smaller structure has lesschance of possessing a number of different centres than a large9ne (resfing bacteria). That enzyme action is due to active centresreceives support from the observation that preparatioirs fromB.coli of “ soluble ” lactic acid enzymes have the same specificadsorbing power on a particular type of compound as has the lacticacid centre (enzyme) of similar (resting) b a c t e r i ~ ~ It is of interestto compare their hypothesis with a statement of Willstatter,6 takenfrom a lecture delivered before the Chemical Society last year :Bwchem. J., 1927, 21, 148; A,, 1927, 280.Ibid., p. 1224; A., 1927, 1113.Ibid., 1928, 22, 689; A., 707; Stophenson, ibid., p. 606; A., 649.J . , 1027, 1374224 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.“ It seems that we must consider an enzyme to be composed of aspecifically active group and a colloidal carrier. . .. The colloidalcarrier seems to vary somewhat in its nature, but to be necessary forthe stability of the active group.” Willstatter’s conclusions arebased on the separation and purification of “ soluble ” enzymes, anddiffer from those of Quastel and Wooldridge only in emphasising anactive group instead of an active centre. Cook and Woolf havefurther investigated the observation of Quastel and Woolf * thatB. coli under anaerobic conditions can effect a reductive deamin-ation of aspartic acid to succinic acid, and that under the influenceof growth inhibitors such as toluene the following reversible equi-librium is established : aspartic acid e fumaric acid + ammonia.Eleven other bacteria have been shown to bring about the formerreduction, but the equilibrium is only established by the fourfacultative anaerobes and appears to be specific for aspartic acid.It is suggested that two distinct mechanisms capable of dealing withthis amino-acid are present in bacteria.The observation is of greatinterest not only because biological synthesis of amino-acids hashitherto been effected only by perfusion of the isolated liver witha-ketonic or hydroxy-acids, but because it may help to explain theconnexion in plant metabolism between the succinic acid producedby oxidation of fats and sugars and the accumulation of asparaginewhich occurs when excess of nitrogen is present.Aerobic and Anaerobic Oxydases.Pugh and Raper9 have recently suggested a convenient, butadmittedly provisional classification of the oxydases.Those whichact only in the presence of oxygen or a peroxide, and compriseperoxydase, tyrosinase, and the thermostable catalysts known aspolyphenolase, are referred to as aerobic oxydases, whereas theoxido-reductases (dehydrases) and the thermostable catalystsworking in conjunction with glutathione, which will act anaerobic-ally provided a suitable hydrogen acceptor is present, are referredto as anaerobic oxydases.Raper has recently reviewed the present knowledge of theaerobic oxydases.1° Bach and Chodat’s well-known theory of thedual nature of the direct plant oxydases-in which the oxygenaseis regarded as an oxygen carrier which forms a peroxide on exposureto air, which can then be activated by peroxydase-and Onslow’smodification-which suggests that oxygenase is really a mixture ofan enzyme and a pyrocatechol derivative which react together inBiochent. J ., 1928, 22, 474; A., 551.lbid., 1927, 21, 1370; A., 1928, 202.* Ibid., 1926,20, 645; A., 1926, 868.lo Physiol. &2&w8, 1926, 8, 246BIOCHEMISTRY. 225the presence of air to give a peroxide-are subjected to considerablecriticism. Raper points out that the guaiacum reaction is given byfive oxidation systems the components of which may and do occurtogether in many plant-tissues, and suggests that the oxygenase ofOnslow is either tyrosinase or a polyphenase of the laccase type.Both of these oxidise pyrocatechol in the air to produce o-benzo-quinone and if guaiacum is added it will be turned blue.This viewis contested by Onslow and Robinson,ll who maintain their claimthat higher plants contain an enzyme giving the ‘‘ direct oxydasereaction ’’ with guaiacum which catalyses the auto-oxidation ofo-dihyctroxy-compounds with the probable production of hydrogenperoxide and o-benzoquinone, and see no reason for discarding theterm “ oxygenase ” for the enzyme which primarily catalyses theo-dihydroxy-group. The investigakions of Raper 12 into the pro-duction of melanin from tyrosine by tyrosinase have now beenbrought to a successful conclusion. Some of the tentative sugges-tions put forward in 1926 have not been substantiated and Rapernow puts forward the following series of reactions :CH2*CH(NH2)*C0,H ~ E O O - C H 7H2) *C02H1Red substance.Colourless substances.3 : 4-Dihydroxyphenylalanine, the &st product of the reaction,is oxidised to the corresponding quinone.By intramoleculararrangement, followed by oxidation, the 5 : 6-quinone of 2 : 3-dihydroindole-2-carboxylic acid is formed, which is believed tobe the red substance, the first visible product of the reaction.The enzyme is necessary for the production of this substance, butit is not required for the further oxidation to melanin. If thedecoloration of the red compound is rapid, 5 : 6-dihydroxyindole-2-carboxylic acid is formed; if it is slow, as happens in an inertl1 Bioclwm. J . , 1928, 22, 1331; A., 1282.13 Ibid., 1927, 21, 89; A., 1927, 378.REP.-VOh. n v . 226 ANNU& REPORTS ON THE PROGRESS OB UHEMISTRY.atmosphere a t room temperature, then carbon dioxide is lost and5 : 6-dihydroxyindole is produced.The actual constitution ofmelanin is still obscure, and it is not yet certain if the melaninsfound in animal cells are produced by a similar series of reactions,but the existence in the melanoblasts of the epidermis of the skinof an enzyme (apparently not tyrosinase) which produces a melaninfrom 3 : 4-dihydroxyphenylalanjne, and the presence of that amino-acid in the wing coverings of cockchafers, is strong evidence insupport of this theory. The function of tyrosinase in the plantstill remains obscure : the suggestion of Szent-Gyorgyi l3 that it isof importance in the respiratory processes of plants has been shownby Platt and Wormall l4 to be untenable.Recent research in the field of anaerobic oxydases has centredround the specificity of the various dehydrases.The succino-dehydrase was first extracted from muscle by Ohlssoii 14@ and wasfound to convert auccinic acid in the presence of methylene-bluepartly into fumaric and partly into malic acid. It has now beenshown that this is due to the presence of two separable enz.y~nes,~~succino-dehydrase, which converts the succinic acid into fumaricacid, and fumarase, which will bring about a reversible equilibriumbetween fumaric and malic acids.Hahn and Haarman l6 have shown that washed minced muscle inthe presence of methylene-blue will dehydrogenate malic acid tooxalacetic acid, which was isolated as the semicarbazone. Thisobservation is of interest in view of the fact that Quastel wasunable to demonstrate it with resting B.coli, although measurementsof the gaseous exchange suggested that it must be a,n intermediaryproduct in the fermentation by that organism of succinic acid toacetic acid.1'Lactic dehydrase has been prepared from B. coli by Stephenson l8and from yeast by Bernheim.19 Both these preparations act slowlyon a-hydroxybutyric acid, but the reaction products have not beenidentified. Hahn, Fischbach, and Haarman 20 show that washedminced muscle will effect the dehydrogenation of lactic to pyruvicacid, which was isolated as the phenylhydrazone. Bernheim l9 alsoclaims t o have isolated a citric acid dehydrase from liver.l3 Bwchem. Z., 1926 162, 399; A., 1926, 99.14 Biochem. J ., 1927, 21, 26; A., 1927, 384.I4a Skand. A c c ~ . Physiol., 1921, 41, 17.l5 &wall, ibid., 1928, 64, 11; Physiol. As., 1928, 349; Clutterbuck,Biochem. J . , 1928, 22, 1193; A., 1281.l6 2. Biol., 1928, 88, 91; A., 1281.,4nn. Reporta, 1925, 22, 231.Biochem. J., 1928, 22, 605; A,, 549.lo Ibid., p. 1178; A, 1281. ** 2. Biol., 1928, 88, 89; A., 1281BIOCHEMISTRY. 227It was stated by Michlin Zoa that the aldehyde oxydase which heprepared from potato by precipitating the watery extract withacetone would reduce nitrate, but not methylene-blue. Bern-heim 21 has now shown that, if regard be paid to the pE, reductionof the dye does take place. The enzyme can therefore be classifiedas a dehydrase, as can also the xanthine oxydase.Bernheim hasrecently discussed the specificit-y of the dehydrases, and inclines tothe view that each substrate has its specific enzyme, i.e., accordingto Quastel’s theory it is activated by adsorption a t specific activecentres. He admits, however, that the evidence is not conclusive,for it would then be necessary to assume that xanthine oxydaseconsists of two entities, an aldehyde oxydase and a purine oxydase.No evidence of this has been detected by Dixon and Kodama,22who have concentrated the milk enzyme 4000 times.With regard to the function of the anaerobic oxydases it isgenerally accepted that they activate hydrogen in the substrate onwhich they act, that is, they may convert substances such assuccinic acid, which are not usually regarded as reducing agents,into such.Further, there is evidence that they activate molecularoxygen. Raper z3 considers that under these conditions of widenedoxidation-reduction potential the succinic acid, or in living cellseven more stable substances such as saturated fatty acids, can beoxidised. As Thunberg 24 finds evidence of these enzymes in thehigher plants, their presence in the protoplasm of living cells isprobably universal, and it becomes of interest to inquire whetherreduction potentials have been observed in living cells.Hydrogen-ion COB ceWa.tion and Beduction Pofe.zLtinb of LivingProtoplum.It is essential that the normal condition of the protoplasm bemaintained when either of these factors is being determined. Thefirst t o realise this condition experimentally were Needham andNeedham,Z5 who made use of the new micrurgical techniquedeveloped by Chambers.By micro-injection of appropriate dyesthey were able to show that the internal pH of a number of speciesof marine ova was 6-6 and that this value fell to below 6.0 oncytolysis of the cell. They showed later z6 that the pn of Arnabaproteus was about 7.6, and that the cell was not only capable ofBiochem. Z., 1927, 185, 216; A., 1927, 699.21 Biochern. J . , 1928, 22, 344; A., 550.22 Ibid., 1926, 20, 1104; A., 1926, 1175.23 Physiol. Reviews, 1928, 8, 245.24 XIIth Int. Cong. Physiol., 1926, 161; A., 1928, 550.Proc. Roy BOG., 1926,33, 99, 173; A., 1926, 194.26 Tbid., p. 383; A., 1926, 545228 ANNUAL REPORTS ON 178E PROGRESS OF CHEMISTRY.reducing the oxidised forms of indicators of more positive potentialhut also of oxidising the leuco-forms of indicators of oxidation-reduction potential lower than its own, and that there mas a fairlyconstant reduction potential zone lying between rH 17 and 19,which they concluded was widely independent of the concentrationof oxygen in the external atmosphere.Chambers, Pollack, andHillar 27 found that the internal pu of both A. proteus and A . dubiawas 6.9 &- 0.1, that they possessed considerable buffering capacity,and that a significant change of pH was associated with the deathof the cell. Extending their studies with starfish eggs, Chambersand Pollack 28 differentiate between the pn of the cytoplasm, whichwas 6.7 & 0.1, and of the nucleus, which was 7.6 & 0.1.Morerecently Cohen, Chambers, and Reznikoff 29 have determined thereduction potentials of A . dubia and their results are only in partialagreement with those of the Needhams. They consider that ininterpreting reduction phenomena of micro-injection it is necessaryto take into consideration the intensity, capacity, and rate factors.We shall deal with these points in turn. 1. Reduction intensity.Under anaerobiosis the amoeba develops in its interior a high,primary reducing potential with a value certainly less than r, 7.6.Under aerobiosis the neutralising effect of the atmospheric oxygenshifts the r, to any value between 13 and 18, depending on secondaryfactors. This range corresponds to the well-known effect found inaerated suspensions of cells, namely, a gross reducing intensitystabilised between 0.1 and 0.2 volt a t pH 7 0 0 .~ ~ 2. Reducingcapacity. Under anaerobiosis the amoeba appears to contain onlyactive reductants, and therefore has no poising ability. Inter-ference of oxygen complicates the picture by introducing oxidantsof all shades of activity and elaborated presumably a t varyingrates. 3. The rate factor. The danger of applying to the dynamicactivity of the heterogeneous system of the cell some of the criteriaestablished for essentially static, homogeneous indicator systems isrecognised, as these require the introduction of a time factor.Despite the complexity of the subject, the authors consider thatthe almost instantaneous reduction of the indicators on the electro-positive side is strong evidence for the existence of a virtual labile,reversible equilibrium state.All these micrurgical studies suggest that there is a uniform p aand rH distributed throughout the cytoplasm of these simple cells.In accepting this conclusion the limits of the methods employed,27 Proc.SOC. E x p . Biol. Med., 1926-7, 24, 760.28 J . @en. Phy8/siol., 1926-7, 10, 739; A., 1927, 696.2s Ibid., 1928, 11, 686; A., 793.30 U.S. Pub. Health Ser., 1926, Suppl. 56, 1; A., 1926, 1009BIOCHEMISTRY. 229resting as they do on colour changes observed under the microscope,must be kept in mind (Cohen, Chambers, and Reznikoff discussthem in great detail). In living cells the protoplasmic proteins arewithin, or not far away from, their isoelectric range; consequentlya small local change of pH may have a pronounced effect on theirphysical properties.Protoplasmic streaming is itself almostsufficient proof that such local changes must occur, and there isalso the observation of O~terhout,~~ referred to in last year’s Report,showing a difference of potential of 14-5 millivolts across the proto-plasm of valonia. That the dye injection method is still too crudeto permit one to follow possible local changes of metabolic activityis also apparent. Fertilisation of the egg of the sea urchin is knownto be followed by an enormous increase in the oxygen consumption,yet the Needhams failed to observe any coincident decrease in ther,.Cannan 32 has pointed out that a change of two or three unitsof r,, which the method is incapable of observing, correspondsto an increase of several hundredfold in the concentration of thereduced pigment (echinochrome), and therefore of oxygen consump-tion. The possible presence of large local gradients of r, alaofollows from another observation of Cannan’s 33 connected with theoxidation-reduction indicator hermidin, which is present in the leafcells of Mercurialis. The indicator is held 95% reduced, corre-sponding to rH 10 and an oxygen pressure of only atmosphere.Yet during photosynthesis the chloroplasts must be in equilibriumwith atmospheric oxygen. Now oxygen does not appear to exertanything like its full potential in biological systems, and Cannan,Cohen, and Clark assign to “ biological oxygen ” an oxidationintensity of about r H 18.This would still give a difference ofpotential of a t least 0.2 volt between the chloroplasts and thevacuole sap containing the hermidin. Bearing these facts in mind,it would appear that the conditions of pH and r, in the cell maybe far from uniform and that the expression “ isoelectric point ”of the cell, used by certain physiologists, has very little, if any,significance.The Transport of Organic Substances in Plants.One of the chief reasons why our present knowledge of plantmetabolism is inferior to that of animal metabolism is the lack offirst-hand information as to the channels of transport of materialin the plant, and of the chemical nature of the substances trans-ported.The sap flowing from one part of a plant to another,31 Ann. Reports, 1927, 24, 236.3% Biochem. J . , 1927, 21, 184; A,, 1927, 271-33 Ibid., 1926, $20, 927; A,, 1926, 1183230 A?K"AL REPORTS ON THE PROGRESS OF CHEMISTRY.which would yield information corresponding to that giveu by theblood and lymph of animals, cannot be obtained in any quantityfrom a plant without injury; consequently to gain some knowledgeof the general problem of translocation in the plant the physiologisthas had to rely on external observation and histological research,and the chemist has had to be content with gross analyses of tissues.Until recently the subject remained one of purely academic interest,but there is now increasing evidence that many agricultural prob-lems demand as an aid to their solution a greater knowledge of thisquestion than we at present possess.As examples of work publishedduring the present year may be mentioned that of whofinds that tomato plants suffering from Western yellow blightaccumulate excess of carbohydrate in a manner which suggeststhat they have lost the power of translocating nitrogen, and ofJohnston and D ~ r e , ~ ~ who show that in the same plants borondeficiency leads to a breakdown of the conducting tissues and anaccumulation of sugars in the leaves. Its importance has beenrecognised by Mason and Maskell,36 working at the Cotton ResearchStation, Trinidad, who have published during the year two papersof outstanding interest dealing with the transport of carbohydratesin the cotton plant.For many years now the view has been widely held that (brieflystated) the sugars and other products manufactured in the leaf aredistributed about the plant by means of the sieve tubes, and thatthe trachez of the wood serve only for the upward transportationof materials from the root system.Dixon 37 recently reviewed thewhole question, and showed that, if the organic matter necessaryfor the growth of a, potato tuber was traiislocated downwards solelythrough the sieve tubes, a, 10% solution of sugar would have tomove a t about 50 cm. per hour. Such a rate seems incredible, andDixon suggested that the wood alone admits of such high rates ofmass movement's of solution.To test, if possible, the validity ofthis assumption Mason and Ma~kell,~~ in a well-planned series ofexperiments, have attempted to follow the movement of carbo-hydrates in the cotton plant by regional analysis of the tissue.The results of many hundreds of analyses of " total carbohydrates,"'' total reducing sugars," and sucrose are statistically presented.Examination of the diurnal variations shows that the variation inthe total concentration of sugars in the leaf can be correlated morereadily with that in the bark (which contains the sieve tubes) thantvhe wood. By ringing the stem and also by partial stripping of the36 Ann. Bot., 1928, 42, 189, 571; A., 559, 1061.34 Plant P/by8iol., 1927, 2, 163; Physiol. A h . , 1928, 66.35 Science, 1928, 67, 324.3' Brit.As8oc. Repork?, 1922, 193BIOCHEMISTRY. 23 1bark they show conclusively that the downward movement of sugarfrom the leaves takes place in the bark along a well-marked gradientin sugar concentration, and that the direction of this movement canunder certain conditions be reversed. Further, examination of theradial distribution of sugars in the bark shows that there is a highpositive correlation between the percentage of sieve tubes in anyone zone of bark and the sucrose coiicentration in that zone.Their results leave but little doubt that the transport of sugar takesplace in the sieve tubes, and that most of the sugar is t’ransportedas sucrose. Further, they show, by calculat’ions based on rates oftransport of sugars and gradients of sugar concentration, that thesugar moves in the sieve tubes by a process analogous to diffusion,but the observed diffusion constant of sugar in the sieve tubes isabout 40,000 times as great as the diffusion constant for sugar in a2% solution of sucrose in water.If sugar in the sieve tubes canmove a t such high rates, then Dixon’s 50 cm. per hour may not beso improbable; even so, to quote Mason and Maskell, “ . . . theproblem of the exact mechanism by which such high absolute ratesof movement are maintained remains quite unsolved.”Chemical Composition of Apples.In last year’s Report attention was directed to the great com-mercial importance of the investigations which are being undertakenin this country to determine the factors which favour or preventdeterioration of fruit in storage.The Report of the Food Investig-ation Board for the year 1927 38 deals very fully with apples, andmuch of the research described is of biochemical interest.The well-established fact that the good keeping quality of applesis associated with slow consumption of respirable material suggeststhat the onset of physiological disease during storage is due toexhaustion of some substances necessary to the process of respiration,either as food or as catalyst. Investigations of losses of dry weightof apples kept in store are shown by Haynes and her co-workers 39to be losses of sugar and acid only. They show further that thepercentage of acid lost was low when nitrogen was low, and thatthe percentage of sucrose inverted per unit of nitrogen was directlyrelated to the acid originally present.Internal breakdown in coldstorage they consider depends on whether the amount of sucrosefalls below that required by the apple. Cold storage retards theinversion of sucrose in a marked way. In apples with a lownitrogen (protoplasmic) content the rate of inversion is more rapidthan that of oxidation, and the keeping quality is good. HighD.S.I.R., H.M. Stat. Office, 1928.Ann. Bot., 1928, 42, 1, 29, 541; A., 558, 558, 802; Biochem. J . , 1928, 22,947; A., 1061232 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.nitrogen, on the other hand, involves a large consumption of sugar,and the amount of sucrose inverted in a given time may be soreduced at 1" that it is insufficient to meet the demands made on it.Internal breakdown then occurs, and death of the apple results.Gas storage at 8" has a retarding effect on the consumption ofsucrose in apples, and probably owes its value largely to this fact.Some interesting research into the chemical composition of appleshas been carried out recently in America by Caldwel1,rn who hasattempted to find out what effect climate and temperature have onthe chemical composition of a.ppIe juice.The quality of dessertfruit is considered to dspend on the total sugar, sucrose, and acidcontent of the juice, and is highest when these are highest. Thetheory, which is widely held in America, that every variety of applehas an optimum mean summer temperature, a t which it attains itsbest development, is confuted.The composition of the fruit of allvarieties shows considerable variation from year to year ; the direc-tion and extent of these variations are determined by opportunitiesfor photosynthesis, and the response to this is simila,r in all varieties,whether grown at high or low temperatures. Seasonal amount ofsunlight, then, is the determining factor, and not temperature.As there is an increasing appreciation in America of unfermentedapple juice as a beverage, the question of blending juices to attainthe requisite palatability has naturally had to be considered.This quality seems to depend on the relative amounts of totalsugar, free acid, and astringent substances present. Varieties ofapples which will give the necessary balance of total sugar and acidcan easily be obtained in America.Caldwell shows that sunshineis again the most potent factor, and that a high annual average forsunshine and temperature produces increased sugar and acidcontents, and decreases astringency. For blending purposes it isiiecessary to have some varieties of apples possessing a high astrin-gent value. As the usual American apple varieties are useless forthis purpose, Caldwell has studied the effect of foreign varieties.French cider apples are shown to be the most suitable, as theyretain their high free-acid and astringent values even after 23 years'growth on American soil. Those who prefer their fruit juicesfermented will no doubt find J. T.Hewitt's 41 monograph on '' TheChemistry of Wine Making " more to their taste.The Structure of the Protein Molecule.Amino-acids.-During the year under review two new amino-acids have been added to the list of the mell-established amino-4O J. Agric. Res., 1928, 36, 289, 367, 391, 407; A,, 802, 802, 1061, 1061.41 Empire Marketing Board, No. 7, H.M. Stat. Office, 1928BIOCHEMISTRY. 233acids derived from proteins. Harington 42 has resolved thyroxine(see also p. 261) and is satisfied that it is a primary constituentof thyroglobulin. In 1922 Mueller * described the isolationfrom several proteins of a sulphur - cont aining amino - acid whichappeared to have the empirical formula C5i&,,0$S. Bargerand Coyne 43a have recently synthesised the substanceCH3-S*CH2*CH,*CH(NH,)*C0,H and have shown that it is identicalwith Mueller's amino-acid.Mueller has agreed with Barger's sug-gestion that the new amino-acid should be called methionine.In addition, several important papers dealing with the puri-fication and properties of already well-established protein amino-acids have appeared. Proline has always been one of the mosttroublesome amino-acids to estimate in the products of hydrolysisof proteins. Separation by means of absolute alcohol is laborious,and crystallisation of the resulting product difficult. Values fortotal proline content of proteins (based on isolation of copperproline or proline hydantoin) have always been considered too low,so that new methods €or the rapid isolation of crystalline proline arevery welcome.Town 44 first prepares the copper salts of the amino-acids of the protein digest, dehydrates these with acetone, andseparates that of proline by taking advantage of its solubility incold methyl alcohol. Pure I-proline is obtained as a white non-deliquescent solid melting with decomposition at 215" and having[a]:' = - 86.8", higher than the value previously recorded.Kapfhammer and also have given a method of preparationbased on Reineclce's salt."6 Lysine, which has hitherto not beenobtained in the free state, is usually isolated as the picrate. Vickeryand Leavenworth 47 have now shown that if the base is adequatelypurified (through the picrate) and is protected from carbon dioxideit crystallises readily in needles which decompose a t 224" andhave [a]:' = +14.6".They have also improved the techniquefor the crystallisation of free arginine and free histidine.48 Othervaluable papers dealing with the preparation in bulk of the indi-vidual hexone bases should be noted.49 The four dissociationconstants of cystine have been determined by Cannan and Knight.5042 Private communication.43a In the prass; referred t o by Vickery and Osbornc, Physiol. Rev., 1928,44 Biochem. J., 1928, 22, 1083; A,, 1148.4b Z. phy8kZ. Chem., 1927,170, 294; A., 526.4? J. Bwl. Chem., 1928,16, 437; A., 400.49 Vickery and Leavenworth, {bid., 1938,78, 627; A,, 1121; Kapfhammerand Spiirer, 2. physioE. Chew., 1928, 1'93, 245; A., 667; Cox, J . Biol. Ghem.,43 Ann. Reports, 1922; 19, 184.8, 393.46 Ibid., p.289; A,, 542.48 Ibid., p. 701; A., 511.1928,78, 475; A,, 99%m Biochem. J . , 1927, 21, 1384; A., 1928, 128.H234 ANNUAL REPORTS ON THE PROGRESS OB CHEMISTRY.Prom a consideration of the solubility of isoelectric cystine, Andrewsand E. J. de Beer 51 postulate the existence of four isomeridea.A new method for determining phenylalanine by oxidation tobenzoic acid with potassium dichromate in acid solution has beendescribed. 52Separation of the Hexone Bases.-The classical method devisedby Kossel and Kutscher 53 and modified by Kossel and Patten *was based on the assumption that only the hexone bases wereprecipitated by phosphotungstic acid in acid solution, and that thesilver salts of arginine and histidine were precipitated at differentdegrees of alkalinity. Three fractions were obtained, from whichlysine was isolated and weighed as picrate, and the other two basesestimated by determination of nitrogen in their respective fractions.The accurate determination of these three bases is of the greatestimportance in view of recent developments in the physical chemistryof proteins, so a reinvestigation of the problem by Vickery andLeavenworth 55 is particularly welcome.Their investigation hasbeen very thorough, and a complete account of their results andtheir criticisms of the older methods cannot be given here. Briefly,they show : (1) Phosphotungstic acid in acid solution does notprecipitate the whole of the arginine and lysine. (2) Both thesebases (under certain conditions) can be quantitatively precipitatedfrom the hydrolysate as silver salts.Precipitation with phos-photungstic acid is unnecessary except in the case of lysine, whichis known to give a much less soluble phosphotungstate. (3) Thesilver salts of arginine and histidine can be sharply separated atpH 7.0, the histidine being completely precipitated. Each base isthen converted into the crystalline dinitronaphtholsulphonate andweighed. (4) An accurate determination of the bases cannot bemade with it sample of protein less than about 350 grams. Withthe customary sample of 50 grams the results are about 10% low.(5) Their results compared with those obtained by the Van Slykemethod show agreement only in the case of arginine: the otherbases are lower.The following table gives the results of theiranalysis of edestiii together with that of Kossel and Patten.Per cent. of protein.kginine. Lysine. Histidine.Vickery and Leavenworth ......... 15.68 1.97 2.16Kossel and Patten .................. 14.17 1.66 2.19Such differences may at first sight seem small, but in relation tothe chemistry of the protein molecule they are of prime importance,6a Bwchem. Z., 1928,194,l. J . Phy8icctl Chem., 1928,32,1031; A, 950. '' 2. physiol. Chern., 1900, 31, 165. '' J . BioE. Chm., 1928, 76, 707; A., 611.W d . , 1903, 38, 39BIOCHBMISTRY . 235as is exemplified by the analysis of the bases of horse haieluoglobimS6The iron content of this protein leads to a minimal molecular weightof 16,670, and the sulphur content to 8,220.The recent ultra,-centrifuge experiments of Svedberg and Fahraeus 57 and osmoticexperiments of Adair 58 leave little doubt that the true value isaround 66,800. Accepting the latter figure, the agreement betweenthe calculated and the found values for the number of moleculesof the respective bases is as follows :Histidine.. ...................... 33 7-66 7-84Arginine ........................ 12 3-13 3-1 1Lysine ........................ 37 8.09 8.10Number of molecules. Calculated. Fouid.Such data show, first, that, as these molecular proportions arenot divisible by four, the hzemoglobin molecule is not formed offour symmet8rical parts. Secondly, they enable biologists tocalculate with a fair degree of certainty the acid-binding capacityof the blood proteins.Equally exact methods are now urgentlyrequired for the determination of the dicarboxylic acids-especiallyof hydroxyglutamic acid. A micro-method for determiningHausmann numbers that may be of use in characterising smallamounts (0.1 gram) of proteins has been devised by Thimann.59Estimation of Amino-nitrogen.-Foreman 6o has published a veryingenious method of estimating certain ‘‘ groups ” in biologicalfluids, which is an elaboration of his earlier method of titratingamino-acids in the presence of a large excess of alcohol.61 Whilstoffering no advantages in the estimatim of the amino-nitrogen inprotein hydrolysates, the method should find wide application inplant and bacterial chemistry, since for the first time it enables usto determine volatile bases (including ammonia), non-volatileamines, and amino-acids, besides certain other “ acidities ” whichare useful for purposes of comparison.Linderstrom-Lang 62 has recently discussed from a practicalstandpoint the theory of the titration of amino-acids and, havingselected on theoretical grounds the requisite indicator, naphthyl-red, has shown that all the free amino-groups of the naturallyoccurring protein amino-acids can be quantitatively titrated in90% acetone with N/lQ-alcoholic (90%) hydrogen chloride.Sorensene3 has used the method in his recent enzyme studies5 6 J.BioE. Chenz., 1928, 79, 377.57 J . Amer. Chem. SOC., 1926, 48, 430; A., 1926, 340.58 Ibid., 1927, 49, 2524; A., 1927, 1212.50 Biochem.J . , 1926, 20, 1190; A., 1927, 66.6O Ibid., 1928, 22, 208; A., 448.62 Compt. rend. Tmv. Lab. Car1?8berg, 1928, 17, 1 ; A., 313.63 Ibid., No. 7 ; A,, 922.e1 Ibid., 1920, 14, 451236 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.(see p. 245) and states that in the presence of proteins or theirmore complex derivatives it is superior to the method of VanSlyke.It may be advisable here to call attention to the developmentsthat have recently taken place in respect to the theory of the dis-sociation of ampholytes, as these have an important bearing on thesignificance to be attached to the dissociation constants of amino-acids. The older conception postulated that the constant involvedin the titration of an amino-acid in the acid range of pH concernedthe amino-group, and was therefore referred to as the basic dis-sociation constant, pkb.Similarly titration in the alkaline rangegave the acid dissociation constant pka. In the isoelectric rangethe ampholyte was considered to be practically undissociated.Adams 64 was the first to suggest that the reverse significanceshould be attached to these constants. Bjerrum 65 has morerecently advocated the same views and. regards the amino-acid inneutral solution (“ undissociated ”) as present almost entirely as“ Zwitterion ” +NH,.R*CO*O-. On the addition of acid theionisation of the R-CO-O- groups is suppressed and +NH,-R*CO-OHions are formed. Consequently a titration through the acid rangeof pH involves the acid group, and not the basic group, as washitherto supposed.Similarly, the titration through the basic rangeof pH leads to the formation of NH,*R-CO*O- ions, and involvesthe basic group. The dissociation constants determined by titrationfrom strongly acid to strongly basic range of pH are designatedusually as p K , , pK’,, etc., without defining the nature of thegroups involved, and in the case of a monoamino-monocarboxylicacid such as glycine pK’, becomes the dissociation constantattached to the carboxyl group and pK’, to the amino-group. Thenew constants are related to the older ones in the following way :pK’, = pkm - pkb and p K f 2 = pka. Bjerrum’s views lead to amuch more rational explanation of the behaviour of amino-acidsand proteins in solution than those hitherto employed, and theirgeneral adoption by those engaged in protein research and by authorsof text-books on biochemistry is to be recommended.Bronsted’s treatment of ampholytes, based on the followingrelation between acid (S), base (B), and hydrogen ion (H+), B +H+ S,G6 has been used with advantage by Linderstrom-Lang,GZwhose paper contains a discussion (in English) of its application tothe titration of amino-acids.64 J .Amer. Chem. SOC., 1916, 38, 1503.66 2. phyeikal. Chem., 1923, 104, 147; A., 1923, i, 444.66 Rec. trav. ch$m., 1923, 42, 718BIOCHEMISTRY. 237Recent Researches into the Structure of Me Protein Molecule.During the past few years a bewildering number of papers haveappeared which seek to throw fresh light on the constitution andstructure of the protein molecule.Abderhalden has been par-ticularly active in this field, and one is grateful for the review byKlarmannYs7 which is more or less an exposition of Abderhalden’sviews. Briefly stated, his hypothesis is that proteins are essentiallycomplex compounds of which the components are substances con-taining amino-acids which are, in part at least, in peptide-anhydrideunion with each other. It is supported by experiments upon partlyhydrolysed proteins which show : (I) diketopiperazines can beisolated from such material ; (2) piperazines can be isolated if thematerial is previously reduced with sodium and alcohol ; (3) positivecolour reactions for dilcetopiperazines can be obtained ; (4) oxamidecan be obtained after oxidation of the material with permanganate.Vickery and Osborne 68 have also recently published a review ofhypotheses of the structure of the protein molecule, in which theviews of Abderhalden (summed up in the words given above) andof Bergmann, Karrer, Brig1 and Held, and of Troensegaard are con-structively analysed and their value contrasted with that of thewell-known peptide hypothesis of Hofmeister.They rightly prefacetheir review with an historical introduction in which they emphasisethe momentous effect that the peptide hypothesis, as developed byFischer, has had on the trend of protein research since the end ofthe last century, and they insist that new hypotheses must gofurther than the exemplification of possible new unions of simpleamino-acids, but must be in keeping with well-established facts ofprotein chemistry and must help to explain the still obscure pheno-mena of denaturation, the exfraordinary solubilities of proteins,their enormous molecular weights, and the mode of action of theproteolytic enzymes, especially of pepsin.The mass of evidencethat has accumulated furnishes nearly conclusive proof that thepeptide bond occurs to a very considerable extent in proteins, butthe view that the protein molecule is essentially a single largepolypeptide does not readily explain the phenomena, mentionedabove. Fischer realised that other types of combination mightoccur and his suggestion of the diketopiperazine ring is the origin ofAbderhalden’s extensive researches.Vickery and Osborne, whosecriticisms and conclusions can only be briefly referred to here, admitthat the sum total of the latter’s evidence is impressive, but pointout that he has not yet shown that any material portion of the6 7 Chem. Reviews, 1927, 4, 51.6 8 phg8Wl. Reviews, 1928, 8, 303238 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.protein molecule is thus constituted. Furthermore his synthebicproducts, and also those of the other investigators mentioned above,are without exception resistant to the proteolytic enzymes. Vickeryand Osborne consider that the peptide hypothesis, in spite of certainshortcomings, is still the foundation stone of protein chemistry, andthat advances in the near future may be looked for in the directionof an expansion of this hypothesis.The acid-base relations of proteins, the theory of which rests onthe peptide hypothesis, was summarised by Cohn in 1925.c9 Fromthe standpoint of protein structure the most arresting publicationssince that date have been those of Simrns.'O On the assumptionthat the free groups in a protein have the same dissociation con-stants as they have in the simple amino-acids to which they belong,he has determined the number of equivalents of each respectivegrouping which must be present to give the experimental titrationcurve of the protein.In the case of gelatin the agreement betweenthe number of equivalents given by the titration curve and thenumber of equivalents of the tervalent amino-acids known to bepresent from actual analysis is satisfactory except in the case ofarginine.The titration curve indicates no group with a dissociationconstant similar to that of the guanidine group in arginine @K' =S.1) but instead an equivalent amount of a weak basic group(pK' = 4.6). Simms suggests that in the unhydrolysed moleculethis amino-acid is present in some tautomeric form, which he calls'' prearginine." More recently he has studied edestin in a similarway. As before, all the arginine is present as '' prearginine," andSimms further shows that this is not converted into arginine onhydrolysis with pepsin up to 18% of the total possible hydrolysis.It is of interest here to recall the fact that Schryver has repeatedlystated that the diamino-nitrogen of gelatin formed after acidhydrolysis is increased if the gelatin is first treated with cold dilutehydrochloric acid.Recently Schryver and Buston '1 claim t ohave shown that the increase is due partly to an increase in arginineand lysine and partly to the presence of dl-lysine, which has not beenpreviously recognised as a hydrolysis product of proteins. Theyconsider that this has not arisen by racemisation of ordinary activelysine and suggest that it is derived from some other unknownconstituent of the protein. The presence of dl-Iysine cannot explainSimms's " prearginine "-further, Simms's curves show that, ifthis excess of base is actually present in the unhydrolysed protein,the second amino-group must also be bound in peptide or other6B PhysioE.Reviews, 1925, 5, 349.70 J. Gen. Phy8/sioE., 1928, 11, 629; A., 837; ibid., 12, 231.Proc. Roy. Soc., 1927, B, 101, 619; A., 1927, 786BIOCHEMISTRY. 239linkage. ‘‘ Vrmrginine ” mixfit remain n sirggestion until furtherchemical evidence is available.Another interesting fact that emerges from Simms’s titration ofedestin is that 50% of the extra, carboxyl groups of aspartic andglutamic acids are bound in some way other than as amides, whichsuggests the presence of anhydrides.Svedberg and his colleagues have found by the centrifugal sedi-mentation equilibrium method that the molecular weight of phyco-erythrin is 208,000 &- 8000, of phycocyan 106,000 & 5000, and ofhEmocyanin 4.93 x 106.72 Such data are of the greatest value,€or besides giving us the actual dimensions of the protein moleculethey act as an independent check against methods based on chemicalanalysis, which can in any case only give minimum values formolecular weight.Contributions to the problem of the structure of the proteinmolecule have been made by Willstatter and Waldschmidt-Leitzduring the past three years, but an account of their work would bevery incomplete without a discussion in some detail of their veryimportant researches on the characterisation of the proteolyticenzymes.Mode of Action and Specificity of the Proteolytic E?azymes.An account of the work of Willstatter and Waldschmidt-Leitzand their collaborators on the general methods of separating andpurifying enzymes was given in the Annual Report for 1926.73Their aim was to obtain enzymes in as pure and uniform a conditionas possible, so that their action on various substrates could bestudied without mutual interference.Their results during the pastthree years have been far-reaching, for they show that earlierworkers had unwittingly used enzyme preparations that were farfrom homogeneous and obtained, in certain cases, results which arenow shown to be invalid.They distinguish four proteolytic enzyme types, viz., pepsin,inactivated trypsin, activated trypsin, and erepsin. These havebeen prepared in a pure condition with respect to enzyme content,and the investigation of the specificity of their action on varioussubstrates has contributed largely to the advances made.74Erepin.-The older preparations of this enzyme, discovered byCohnheim and used with considerable success by Fischer andAbderhalden to split natural and synthetic polypeptides, have now72 J .Amer. Chem. SOC., 1928, 50, 626, 1399; A., 633, 783.73 Ann. Reports, 1926, 23, 232.?4 See Willstatter, J . , 1927, 1359 (Faraday Lecture); Grassmaim, ‘ I Ergeb-nisse cier Physiologie,” 1928, 27240 ANNUAL REPORTS ON TRE PROGRESS OF CHEMISTRY.been shown to be a mixture of erepsin and trypsin. Waldschmidt-Leitz 76 and his co-workers have prepared from the juice of thepancreas and from intestinal erepsin an enzyme which shows notryptic activity, Le., it is without action on simple proteins or theirhigher degradation products and is capable of hydrolysing only thesimplest polypeptides.The sharp difference that they were able todemonstrate between the actions of these two enzymes is wellillustrated by the following table.+eci$city of pmcreas an,d intestinal proteolytic enzymes.Erepsin. Trypsin.Alanylglycine, glyc ylt yrosine ,glycylgl ycine, glycylalanino , - .....................-leuc ylgl ycine + Leuc ylgly c ylgl y cinePeptone (Merck) -Clupein, Scombrin.. -............... + + + .................. ................Tliymus-histone, casein, fibrin,gelatin, gliadin, zein ......... -I _.I-Trypsin -+-enterokjnase.- ++ +++Until quite recently the hydrolysis of dipeptides was consideredto be specific for erepsin, but Waldschmidt-Leitz 76 and his co-workers have now shown that glutamyltyrosine and phenylalanyl-arginine are appreciably attacked by pancreatic erepsin.Thespecificity of erepsin and trypsin has indeed been the subject ofmany papers from the laboratories of Willstiitter, Abderhalden, andv. Euler during the past two years. The length of the peptide chainis not a determining factor, for the octapeptide of glycine is stillattacked by e r e p ~ i n . ~ ~ The nature of the constituent amino-acidsis of importance, as is shown by the fact that leucyltriglycine isattacked only by erepsin, and leucyltriglycylltyrosine only bytrypsin ; 77 glycyltyrosine only by erepsin and p-naphthalene-sulphonylglycyltyrosine, in which the a-amino-group is substituted,only by t r y p ~ i n . ~ ~ Waldschmidt-Leitz 78 concludes that a freecarboxyl group and a certain electromagnetic character of thesubstrate are necessary for its hydrolysis by trypsin, and that afree amino-group is necessary for erepsin. Since the amides of7 5 Waldschmidt-Leitz and Harteneck, 2.p72ysiol. Chem., 1925, 149, 203;A,, 1926, 323. Waldschmidt-Leitz and Schiiffner, ibid., 1926, 151, 31; A.,1926, 323.7 6 Waldsehmidt-Leitz, Klein, and Schaffner, Ber., 1928, 61, [B], 2092; A.,1401.7 7 Waldschmidt-Leitz, Grassmann, and Schlatter, Ber., 1927, 60, [ B ] , 1906 ;A., 1927, 1112.78 Waldschmidt-Leitz, Schiiffner, Schlatter, and Klein, Ber., 1928, 01, [ B ] ,299 ; A., 446BIOCHEMISTRY. 24 1glycine and leucine are split by erepsin, that enzyme clearly does notrequire the presence of a free carboxyl group.The view that a free amino-group is necessary for the action oferepsin had already been put forward by Euler and Joseph~on.’~They consider that the formation of an enzyme-peptide complex,involving the a-amino-group of the peptide, precedes hydrolysis, andconclude from experiments showing the inhibiting effect of phenyl-hydrazine, potassium cyanide, and sodium sulphite, all of whichcombine with aldehydes, that the a-amino-group attaches itself toan aldehyde group in the enzyme.Waldschmidt -Leitz andRauchalles 8o have further developed this suggestion, and haveshown that the pH curve for the hydrolysis of glycylglycine byintestinal erepsin coincides within the limits of experimental errorwith that of the rate of condensation of glycylglycine with dextrose.In addition they bring forward evidence which suggests that vari-ation of activity of the enzyme with pH is due to the effect of thehydrogen ions on the rate of union of the enzyme and substrate,and not on the rate of decomposition.A warning, however, againstthe too ready acceptance of conclusions drawn from pH activitycurves is contained in a paper by Northrop and Simms.81 Usingintestinal erepsin, they have investigated the rate of hydrolysis a tseveral different ppEI values of five peptides and biuret base. ThepH activity curves differ for different substrates in a way which theauthors think can be predicted on the assumption that erepsin is aweak acid or base with a dissociation constant of and thatthe action takes place between a particular ionic species of theenzyme and of the substrate.For further details the original paper,which contains much theoretical discussion, must be consulted.They conclude that the det’ermination of the relative rates ofhydrolysis of various peptides by erepsin, i.e., the specificity of theenzyme, is a difficult matter except in the case where the pH activitycurves are the same for the different substrates. If this is not so,then the corrections which they consider must be applied to theobserved rates are a t present so speculative that the whole pro-cedure must be regarded as very uncertain. That much of thework being done ak the present time on the “specificity” ofenzymes is premature is one of the conclusions to be drawn fromthe more recent work by Grassmann in Willstatter’s laboratory onthe enzymes of yeast.Dernby 82 in 1917 showed that the proteolytic enzymes of yeastcould be separated into an erepsin, a trypsin, and a pepsin.Grass-79 2. p h p i o l . Chem., 1926, 162, 85; A,, 1927, 175.Ber., 1928, 61, [B], 645; A,, 672.a2 Biochem. Z., 1917, 81, 107; A., 1917, i, 500.81 J. Cew. Phy8iOl., 1928, 12, 312242 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.mam’s work suggests that the formal distinction between erepsiii andtrypsin may either be unnecessary, or have a different significancefrom that which has been assigned to it in recent years.By fractional adsorption on alumina it has been found possible toseparate two different homogeneous enzyme preparations, bothof which appear to be specific, and both of which exhibit propertieswhich until recently had been considered specific for “ erepsin.”These are (1) a dipeptidase, which will hydrolyse only dipeptides,and (2) a polypeptidase, which is inactive on dipeptides, but willhydrolyse tri- and higher pep tide^,*^ and even pept0nes.8~ Thedipeptidase will not attack even a tripeptide, and is only active onthose dipeptides which have a free carboxyl group in the positioncharacteristic for normal dipeptides. Amides of dipeptides,decarboxylated dipeptides, and dipeptides in which the carboxylgroup is in an unusual position, such as glycyl-P-aminobutyic acid,are unattacked.But the last compounds are all attacked by theyeast polypeptidase, which Grassmann suggests requires the presenceof an amino-group, but not of a carboxyl The action ofthis enzyme seems to be as specific as that of the dipeptidase.dZ-Leucylglycylglycine is hydrolysed to dl-leucine and glycylglycine,and glycylglyc yl-Z-leucine gives glycine and glycyl-Z-leucine with notrace of free leucine.86 Such specificity at the present time isunique, and it will be interesting to observe whether Grassmann andhis co-workers can separate such enzymes from other natural sources.Until it is known with some certainty that the so-called animalerepsins and trypsin, which up till now have been considered homo-geneous, are not mixtures of the enzymes which it has been possibleto fractionate from yeast, further work or comment on the speci-ficity of these enzymes seems premature.Trypin.-The researches of Waldschmidt-Leitz and his col-laborators on the specificity of the pancreatic enzymes and theunravelling of the true nature of trypsinogen and trypsin are otherfeats which are of great biological as well as chemical interest.Until the publication of their results the earlier view propounded byBaylisa and Starling in 190287 still found general acceptance.This was that trypsinogen, which was devoid of proteolytic activity,was secreted into the duodenum, in which it met with the enzymeenterokinase and was converted by this into active trypsin.Wald-schmidt-Leitz has shown that this view is erroneous. Try-psinogen,Grassmann and Hmg, 2. physiol.Chem., 1927, 167, 188, 202; A., 1927,794.84 Grassmann and Dyckerhoff, %%id., 1928, 179, 41.85 Idem, Ber., 1928, 61, [ B ] , 656; A., 672.86 Idem, 2. physiol. Chem., 1928,175, 18; A,, 672.137 J . Physiol., 1902, 28, 325BIOCHEMISTRY. 243or inactivated trypsin, or simply trypsin as he prefers to call it, isitself the enzyme, and contrary to the earlier fhdings it possesses aspecific proteolytic activity of its own. It will hydrolyse peptoneand such simple proteins as clupein and scombrin, but is withoutaction on proteins such as casein or gelatin (see Table, p. 240).Activated by enterokinase, it will attack the simple proteins muchmore vigorously and will act on casein and gelatin in the way thatis already well known. The essential difference in the points ofview is that the real enzyme trypsin is the older-so-called zymogen-trypsinogen, and that the enterokinase is not an enzyme as wasformerly supposed, but merely an activator of the trypsin.Thisimportant result has been reached by applying Willstiitter's adsorp-tion methods t o the purification of the enzymes of the pancreas.An extract of dried pancreas contains erepsin, trypsin, andtrypsin-kinase. To this extract a solution of caseinogen is added.88On precipitating the protein with acetic acid the trypsin-kinase isspecifically adsorbed, and is removed by filtration. This operationis twice repeated to ensure complete removal of the trypsin-kinase.The filtrate, containing the trypsin and erepsin, is then treated withkaolin.Trypsin is more basic and is preferentially adsorbed, andby repeating the process a sufficient number of times homogeneouspreparations of the two enzymes can be obtained.89 Enterokinasefree from erepsin can be prepared by precipitating it first withacetic acid, then with mercuric chloride, and decomposing thelatter precipitate with hydrogen sulphide.90 It cannot be pre-pared by adsorption with kaolin or caseinogen, as the specifictrypsin-binding group of the activator is taken up by the protein.Using homogeneous enzyme preparations separated in this way,Waldschmidt-Leitz has been able to demonstrate their respectivespecificities outlined above. Further experiments have shown thatthe enzyme activity of pancreatic juice is only one-fifth that of theextract of the gland,g1 so for experimental purposes the dried glandis more useful than the natural secretion.Using caseinogen as a substrate, Waldschmidt -Leitz and Shinoda 92have investigated the hjdrolytic action of erepsin-free trypsin fromthree dserent animal Bources, activated with erepsin-free entero-Waldschmidt-Leitz and Linderstr6m-Lang, 2.phy8ioZ. Chem., 1927, 166,89 WaIdschmidt-Leitz and Harteneck, ibicl., 1925, 147, 286; A., 1925, i,9O Waldschmidt-Leitz and Kunstner, ibid., 1927, 171, 290; A., 1928, 550;91 Waldschmidt-Leitz and Waldschmidt-Graser, ibid., 1927, 166, 247 ; A,,39 %id., 1928,176, 301 ; A., 922.241 ; A., 1927, 698.1361.Waldschmidt-Leitz, ibid., 1926, 142, 215; A., 1925, i, 741.1027, 698244 ANNUAL REPORTS ON THE PROGXESS OF CHEMISTRYkinase from eleven different animal sources.With trypsin fromthe pig and cat, the activation was the same in all cases; withsea-lion trypsin, the activation was very similar except with theenterokinases from the pig and ox. The difference in the activityof trypsin and trypsin-kinase (trypsin + enterokinase) is not yetunderstood. Both enzymes can be adsorbed on aluminium hydroxideor caseinogen without loss of activity or specificity, but enterokinaseitself is thereby inactivated. Clearly the enterokinase portion ofthe trypsin-kinase molecule which is responsible for the difference inthe specificity of the two enzymes is not concerned directly in theadsorption linkage.93 The magnitude of this difference is wellillustrated by the following experiment, using as substrates four ofthe protamines which have been analysed by KosseLg4 The fisttwo columns show the relative amount of hydrolysis with the twoenzymes, and the third the relative proline content of the proteins,Enzyme./- \ RelativeTrypsin. Trypsin-kinsse.proline content.Clupeine ........................ 0.90 3.10 4Salmine ........................ 1.00 3.18 3Scornbrine ..................... 0.60 2.96 2Sturine ........................ 0.02 3.95 -which shows a rough correlation with tryptic activity. The otherconstituent amino-acids, chiefly arginine, show no correlation at all.Pepsin.-Very active, ash-free preparations of pepsin haverecently been made by 3'. Fenger, R. H. Andrew, and A.W. Ral-s t ~ n , ~ ~ who precipitate the enzyme at pH 2.5. Analysis shows thatit is a protein containing a very high proportion of monoamino-acids,some sulphur and phosphorus, but no halogen. It is doubtful,however, if a neater or more rapid method of purification or con-centration is required than the safranine method originally devisedby Marston 96 and perfected by Forbes.97 The enzyme is quanti-tatively precipitated by the safranine, and can be recovered bydissolving the precipitate in 20% alcohol, containing a little oxalicacid, and extracting the dye with butyl alcohol. Preparations withtwenty times the original activity can be made in this way. Newermethods of determining peptic activity, depending on a new choiceof indicator or dye adsorbed on the substrate, have been published93 Waldschmidt-Leitz and Linderstrom-Lang, 2.phpiol. Chem., 1927, 166,Y1 Waldschmidt-Leitz and Kollmsnn, ibid., p. 261 ; A., 1927, 698.9 5 J. Bwl. Chem., 1928, 80, 187.y o Biochem. J., 1923, 17, 851 ; A., 1924, i, 350.9 i J . Biol. Chem., 1927, '41, 569; A., 1927, 37%.227 ; A., 1927,698BIOCHEMISTRY. 245by Linder~trom-Lang,~~ Beer and P e c ~ e n i k , ~ ~ Citron,l and Kawa-hara and Peczenik.2That the apparent specific action of pepsin is of a different typefrom that of trypsin or erepsin-in which the action is confined tothe hydrolysis of the peptide linkages with the formation of carboxyland amino-groups-has been noted since the early days of formoltitration. Although proteins are changed very materially by theaction of pepsin, the increase of formol titration is relatively verysm.al1, which suggests that its action is more complex than simplepeptide splitting.Confirmation of this is found in the fact thatsynthetic polypeptides are, without exception, unattacked by it.Steudel and his co-workers in 1926 published results which seemedto show that in peptic digestion the increase of acid groups (measuredby Willstatter’s method) was greater than that of the basic groups(measured by Van Slyke’s method). Opposed to this finding werethose of Waldschmidt-Leitz and Sim~ns,~ who showed that in thepeptic digestion of casein, egg albumin, and ricinus globulin theratio of the increases was unity; although they found that otherproteins, such as zein and gelatin, behaved irregularly.Felix andHarteneck found the ratio for thymus histone was unity, as alsodid Weber and Gesenius for casein. Sorensen and Katschioni-Walther have made a critical study of the methods of analysis,and have reinvestigated the problem, using casein, gliadin, andgelatin as substrates. Using Willstatter’s method for estimatingthe acid groups and Linderstrom-Lang‘s method for basicgroups, they find that the ratio of the increases on peptichydrolysis is unity and ascribe the earlier conflicting results tofaulty methods of technique. Waldschmidt-Leitz and Kiinstner 8published at the same time similar results, and as the basic groupshad been estimated by Van Slyke’s method there is no doubt thatthe increase is due to liberation of free amino-groups.They con-clude that peptic hydrolysis is confined to the peptide bond, andthat the extent of such hydrolysis bears a definite and simple ratioto the extent of the hydrolysis by trypsin and erepsin. Sorensen,98 2. physiol. Chenz., 1928, 174, 351; A., 551.99 Pememtforsch., 1928, 10, 8 8 .Deut. Med. Woch., 1926, 52, 1781; A., 1927, 372.Wiera Med. Woch., 1926, 72, 129; A., 1927, 372.a Steudel, Ellinghaus, and Gottschalk, 2. physiol. Chem., 1926,154, 21, 198 ;4 2. physiol. Chem., 1926, 156, 114; A., 1926, 1060.6 Biochem. Z . , 1927,187, 429; A., 1927, 992.A., 1926, 866; Steudel and Ellinghaus, ibid., 1927,166, 54; A,, 1927, 698.Ibid., 1927, 165, 103; A,, 1927, 477.2. physiol. Chem., 1928, 174, 251; A,, 551; Compt.rend. Trav. Lab.Carlaberg, 1928, 17, No. 7.8 2. phy8kd. Chem., 1927,171, 70; A,, 1928, 550246 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.whilst agreeing that such a conclusion would be of great importancefrom the point of view of protein structure, considers that onpresent published evidence it is somewhat premature.The above account of the proteolytic enzymes shows whatpowerful weapons Waldschmidt-Leitz and his colleagues are slowlyforging. Their work is still incomplete, and it is probable that wedo not yet understand the true specificity of these enzymes. IfWaldschmidt-Leitz and his colleagues can, finally, unravel themystery of peptic digestion, they will have made the greatest con-tribution to the problem of protein st'ructure since the peptidehypothesis of Hofmeister and Fischer.Carbohydrate Phosphoric Acid Esters.The Carbohydrate Phosphoric Acids of Yeast cFermentation.--lnthe Report of last year reference was made to the important workof Morgan and Robison on the constitution of the hexosediphos-phoric acid of yeast fermentation, work which led them to thesuggestion that this important intermediary substance was y-fructose-1 : G-diphosphoric acid? Full details of this work arenow available lo and whilst it is not necessary to refer further tothis important advance in the present Report, it is significantthat the suggestions made by Morgan and Robison are stronglysupported in a recent publication by Levene and Raymond.llThese workers show that the rate of acid hydrolysis of the methyl-fructosidic derivative of hexosediphosphoric acid is that of abutylene-oxidic (y-) fructose compound (<2,5>lactal structurein Levene's nomenclature). It follows that the more stablephosphoric acid residue must be in position 6, and the structurefinally deduced for the parent hexosephosphoric acid is the same asthat assigned to it by Morgan and Robison.Levene and Raymondare also in agreement with the suggestion that Neuberg's mono-phosphoric acid, derived from the diphosphoric acid by hydrolyticremoval of the more labile phosphoric acid group, is y-fructose-6-monophosphoric acid.In the past year considerable progress has been made in the studyof the various hexosemonophosphoric acids of biological origin.There is now little room for doubt that previous conflicting resultsrecorded in efforts to elucidate the nature of the hexosemono-phosphoric acid, formed along with the diphosphoric acid in yeastfermentations, are to be ascribed to the presence in th% materialof different monophosphates, an observation which would aIsoseem to apply to the monophosphoric acid of muscle.One of thelo Biochem. J . , 1928, 22, 1270; A,, 1213. -4nn. Reports, 1927, 24, 252.J . Biol. Chem., 1925, 80, 633BIOCHEMISTRY. 247most significant advances which falls to be recorded in this field isthe isolation by Robison and Morgan l2 of trehalosemonophosphoricacid in the come of their studies of the “ monophosphate ” fract,ionof the phosphoric acid esters of sugars formed by yeast.It millprobably be convenient to remind the reader that the diphosphoricacid can be separated readily from the monophosphoric acid invirtue of the much greater solubility of the barium salt of the latter,as compared with that of the former acid. It is in the more solublebarium salt fraction that the interesting new disaccharide mono-phosphoric acid is found, Trehalose is a rare non-reducing di-saccharide found in the “ manna ” excreted by the insect Larinusmaculatus, in certain fungi, seaweeds, and yeast. It has the con-stitution :Glucose7- 0 7H*CH( OH) *CH( OH)*CH(OH) *CH*CH,*OHReducing carbons- (X mutually linked ‘I ~ r H . c ~ ( o H ) ~ c l i ( o ~ ) ~ c ! h e new sugar ester is formed when glucose or fructose is fermentedwith dried yeast or zymin.Under these conditions it comprisessome 10-20~0 of the total phosphoric acid in ester combination,the remaining 80-90 yo being the typical hexosediphosphoric acid.On the other hand, by var-ying the conditions of the fermentationconsiderable alterations can be made in the nature of the carbo-hydrate phosphoric acid esters produced and it would appear thattrehalosemonophosphoric acid is not an obligate product. Forinstance, when yeast juice is used as the fermentative agent thediphosphoric acid fraction is less than half of the total esterifiedphosphorus, and trehalosemonophosphoric acid is not found in thetypical monophosphoric acid fraction, which would appear to consistentirely of monosaccharide esters.Similar variations in thebalance between diphosphoric and monophosphoric acid fractionshave been noted by Kluyver and Struyk l3 in making use of differentsamples of yeast in the presence of phosphates. Thus in fermenf-ations in which there occurs a rapid rise to maximum velocity,followed by a fairly rapid fall to the initial rate, there is found alarge proportion of the diphosphoric acid, whilst in other cases inwhich the increased fermentation, following the addition of phos-phate, is less marked and of longer duration, almost the whole ofthe esterified phosphorus is present as the monophosphoric acid.1z Biochem. J . , 1928, 22, 1277; A., 1285.13 Pmc. R. Akd. Wetmch. Amsterdam, 1927, 30, 871; A., 1928, 398248 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Trehalosemonophosphoric acid has [a]5a6l + 185" for the free acid, + 132" for the barium salt, and + 31" for the brucine salt. It isreadily dephosphated by the action of bone phosphatase and purecrystalline trehalose (m.p. 96-98' ; + 222") is subsequentlyisolated. The ester is fermented readily by dried yeast and moreslowly by yeast juice and zymin. It is not yet possible to state whatsignificance this interesting new phosphoric ester may have in yeastfermentations, but, as Robison and Morgan suggest, it is by nomeans impossible that the introduction of the phosphoric acid groupmay facilitate the building up of complex reserve carbohydratesfrom the simple sugars. That trehalosemonophosphoric acid isformed by some active fermentation process is proved by theobservation that in the dried yeast used in the fermentations neitherfree trehalose nor its monophosphoric ester was found in quantitiessufficient to account for the amount of the latter isolated from thefermentation products.It is not yet possible to express an opinionon the identity or otherwise of the new trehalosemonophosphoricacid with a synthetic product described some years ago by Helferich,Lowa, Nippe, and Riedel l4 as resulting from the action of phosphorylchloride on trehalose in pyridine solution. It had the compositionof a monophosphate and its barium salt had [.ID + 135.5", some-what lower than the corresponding value for the barium salt ofRobison and Morgan's compound.During the past year there has been recorded the preparation ofanother disaccharide monophosphoric acid by biological means.Neuberg and Leibowitz 15found that the action of the lactic acidbacterium, B.Delbrucki, on sodium hexosediphosphoric acid ofyeast resulted in a partial dephosphatisation and gave, in 30%yield, a reducing disaccharide monophosphoric acid, the bariumsalt of which had [aJD + 38" and the free acid + 57". Clearly thisacid differs materially from Robison and Morgan's trehalose ester,but the synthetic analogy is an interesting one.Euler, Myrback, and Runehjelm l6 codrm the observation thatfermentation of glucose by means of dried yeast yields, after separ-ation of the diphosphoric acid as the sparingly soluble barium salt, amonophosphoric acid fraction identical with that first described byRobison, and further claim to have isolated a new hexosemono-phosphoric acid by fermenting glucose with very active yeast.Thenew acid has [elD + 63" and its barium salt [.ID + 33", valueswhich are much higher than those recorded for Robison's mono-phosphoric acid. The possibility of this new acid being con-l4 2. physiol. Ohem., 1923, 128, 141; A., 1923, i, 898.lG L 1 r k i ~ Kenhi. Min., Geol., 1928, 9, 1 ; A., 1158.15 ~ i o ~ h e m . z., 192a,193,237; A,, 447BIOCHEMISTRY. 249taminated with compounds of the type of the new trehalose mono-ester, which possesses a remarkably high rotation, should not yetbe excluded. From their studies of the mono- and di-phosphoricacid fractions Euler and Myrback 17 conclude that the course offermentation of glucose by yeast in the presence of phosphatesproceeds in the following stages : (1) synthesis of Robison's mono-phosphoric acid, (2) conversion of the mono-ester under the actionof a mutase and a co-zymase into alcohol and carbon dioxide andinto the dipbosphoric acid, (3) conversion of the diphosphoric acidby the action of a phosphatase into a hexose, presumably fructose,and (4) the participation of the hexose in the chain of reactionsa t (1).It is well established from the data reviewed in the foregoingand from those previously available, thak by securing appropriateconditions of fermentation, yeast may form a t least four carbo-hydrate phosphoric acid esters, namely, a fructosediphosphoricacid, and three monophosphoric acids, those of trehalose, of analdose (probably glucose), and of a ketose (possibly fructose).Themixture of the two last -mentioned comprises Robison's acid.The Hexosemonophosphoric Acid of .Muscle.-It is not altogetherunexpected to find that puri pnssu with the development of our viewson the phosphoric acid metabolism of the yeast cell, equally strikingcomplexities are brought to light in the investigation of the carbo-hydrate phosphoric acid esters of the muscle. It is now well knownthat by using the fluoride-glycogen fermentative resynthesis, it ispossible to obtain from mammalian muscle pulp a hexosediphos-phoric acid identical with that formed by the yeast cell. On theother hand, the normally occurring hexosephosphoric ester of muscleis a monophosphate.l* The latter has been investigated by Prydeand Waters,lg who obtained from the muscles of rabbit's, goats, anda donkey, preparations which were apparently identical with oneanother and consisted of some 90% of an aldose component asdetermined by a comparison of the copper reduction value with theWillstatter-Schudel hypoiodite figure.This result is in close accordwith that of Embden and Zimmermann.20 Pryde and Waters havesubjected the monophosphoric acid to bromine oxidation, followedby dephosphatisation, using aqueous hydrobromic acid underpressure. The product eventually obtained had the properties ofgluconic acid, and they conclude that some 90% of the musclemonophosphoric acid is derived from glucose.The remaining 10%Anmlen, 1928, 464, 56; A,, 1053. Ann. Reports, 1927, 24, 255.18 Report of the Meeting of the Biochemical Society (Dec. 14th), J . SOC.2O 2. physiol. Chem., 1927, 167, 114; A., 1927, 749.Chem. Ind., 1928, 47, 1346250 ANNUAL REPORTS ON TEE PROGRESS OF CHEMTSTRY.is presumably a ketose monophosphate, but further investigation isnecessary before its identity can be considered as established. Acomparison of the rotations of the free acids and barium saltsprepared from purified yeast and muscle monophosphoric acidfractions suggests that these, if not identical, are constituted onvery similar lines. This view is supported by Lohmanq21 whoshows that the kinetics of hydrolysis of the muscle monophosphoricacid and Robison's yeast acid follows the same course. It is nonethe less clear that great care is necessary in interpreting such resultsin view of the obviously mixed nature of the products obtained bothfrom yeast and from muscle.Modifications in the method ofisolation may lead to changes in the relative amounts of the twocomponents, and although the presence of a disaccharide ester inthe products of the muscle process has not so far been demonstrated,the isolation from yeast fermentations of trehalosemonophosphoricacid, possessing some of the physical properties of the mono-saccharide monophosphoric acids (e.g., solubility of the bariumsalt), is a clea'r indication of the caution necessary in such investig-at ions.Pyrophosphate in Muscle.An observation of the greatest importance has been made byLohmann,22 who finds that a considerable part of the increasedinorganic phosphate observed when muscle pulp is digested withsodium bicarbonate solution is due to the enzymic hydrolysis of apyrophosphate to the normal orthophosphate. Thus it is found thatin the fresh muscle of the frog or rabbit some 0-6 to 0.7 mg.per cent.of P20, (or one-fifth of the total acid-soluble phosphate) is presentas pyrophosphate and is completely hydrolysed to orthophosphateby an alkaline muscle extract at 40-50". The muscle pyrophos-phate has been precipitated as the copper salt from a trichloro-acetic acid extract of muscle and identified as the crystalline sodiumsalt and as the tetramminocobaltipyophosphate (+ 2H20).Sinceartificially prepared pyrophosphates obtained from alkali biphos-phates also show this hydrolysis, and since muscle pulp whenheated for one minute on the water-bath loses its power to hydrolysepyrophosphate, it is inferred that the process is an enzymic one.The muscle pyrophosphate would appear to undergo hydrolysis inrigor. The process is not related to the production of lactic acidin the intact muscle and it may occur in carbohydrate-free media.Further details of this extremely interesting discovery will be eagerlyawaited. Obviously, if it be substantiated, much careful recon-sideration will have to be given to all previous work in which the21 Biochem. Z., 1928,194, 306; A., 666.22 Nai?U?Wi86., 1928, 16, 298; A., 1064BIOCHEMISTRY.251breakdown of lactacidogen in muscle is estimated in terms ofinorganic phosphoric acid liberated. Although a t first sight theenzymic hydrolysis of a typically inorganic product such as amineral pyrophosphate seems remarlcable, there is already a sug-gestive analogy, in that Kitasato 23 has shown, with appropriatecontrols, that sodium hexametaphosphate, (NaPO&, is hydrolysedby taka-phosphatase and by the phosphatases of rabbit liver andkidney, and of yea,st, to yield orthophosphate. More recently, in adetailed study of the range of action of phosphatases, Neuberg andJacobsohn 2* show that the dipotassium salts of di-o-cresol, di-m-cresol, and di-a-naphthol pyrophosphoric acids, that is, compoundsof the typewhere R signifies the organic radical, are hydrolysable by vaeriousphosphatases with the production of orthophosphoric acid.Forexample, the o-cresol derivative showed in thirteen days 90%hydrolysis with a liver phosphatase, 77 yo with kidney phosphatase,and 4.4% with muscle phosphatase. One may therefore infer thatall types of phosphoric acid, ortho, meta, and pyro, in organiccombination may be susceptible to enzymic hydrolysis, and furtherthat inorganic meta- and pyro-phosphates may undergo a similarchange, all with the production of orthophosphoric acid. Theobservations briefly reviewed here suggest a remarkable extension ofour already comprehensive views regarding the biological r6le ofphosphoric acid.Lactic Acid Formation in 2Muscle.-The observations discussed inthe preceding paragraph obviously have an important bearing onthree very well documented studies of the enzymic formation oflactic acid in muscle and the relationship of phosphoric acid to thisprocess.These comprise two contributions by Stiven25 and oneby Beattie, Bell, and Milroy.26 Stiven infers from his results thatphosphoric ester accumulation is not an essential accompaniment oflactic acid formation from glycogen. When ester accumulationdoes occur, there is no definite constant ratio of the molar amount oflactic acid produced to the amount of phosphoric acid that accumu-lates as ester. In the second period of muscle activity, when theester accumulated in the first period is broken down, the molarratio of lactic acid produced to phosphoric acid set free is also veryvariable.Beattie, Bell, and Milroy show that when extracts ofmuscle are incubated a t 22" to 45" in bicarbonate solution there is,23 Biochem. Z., 1928, 187, 257; A., 1282.z6 Biochem. J., 1928,22, 867, 874; A., 796.26 J. Physiol., 1928, 65, 109; A,, 921.24 Ibid., 1928, 199, 498282 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.approximately, an equimolar production of phosphoric and lacticacids. When glycogen is added, formation of lactic acid andesterification of phosphoric acid occur in roughly equimolar pro-portion. It is admittedly difficult to weld into a coherent schemethese diverse results and obviously with the rapid accumulation ofinformation concerning the nature and reactivities of the variousphosphoric acid compounds present in muscle it would be unwise toattempt the task at the present juncture.In last year’s Report 27 detailed reference was made to the im-portant work of Meyerhof on the separation of the lactic acid fermentfrom muscle.An extension of this work has been presented byMeyer,28 who describes in detail methods of purifying the lactic acid-forming enzyme leading to the isolation of preparations 20 to 50times as active as the original material.Boyland 29 has collected interesting data regarding the formationof lactic acid in invertebrate muscle and in vertebrate cardiacmuscle. He finds that the change of glycogen into lactic acidaccompanies activity in invertebrate muscle in the same way as inthe muscle of vertebrate animals. At the same time the musclesof crustaceae, lamellibranchs, and gastropods appear to act as storesof glycogen, and in the last two instances there are found largequantities of glycogen which cannot be converted into lactic acidby the muscle under known optical conditions for this change.Theheart muscle of invertebrates differs from that of vertebrate animalsin not producing less lactic acid than the skeletal muscle of the sameanimal, and in not producing lactic acid in excess of the glycogenpresent. It is suggested that the excess production of lactic acid invertebrate cardiac muscle may possibly be derived from the inositolof the muscle.Phosphagens.The interesting discovery of the existence in muscle of it labileform of nitrogenous organic compound of phosphoric acid (phos-phagen), to which reference was made in the Report of last year,30has led to numerous investigations and further important advances.Irving and Wells 31 have detected the presence of labile phosphoruscompounds of the type of phosphagen in the voluntary muscles ofall vertebrates examined by them with the exception of fishes.They were unable to detect labile phosphoric acid in the smoothmuscle of either vertebrates or invertebrates or in heart muscle.In a general way these workers therefore substantiate the parallelismpreviously observed between the distribution of labile phosphoric18 Biockem.Z., 1928,193, 139; A,, 444. Ann. Reprte, 1927, 24, 268.Biochem. J., 1928, 22, 362; A., 646.a1 J .Biol. Chem., 1928, 77, 97; A,, 666.Ann. Repork?, 1927, 24, 266BIOCHEMISTRY, 253acid and creatine. Martinos2 records that, on comparing themuscles of the rabbit and pigeon, he found that those capable of con-tracting more rapidly contained more phosphagen and less inorganicphosphoric acid. In regard to this question two further recentlypublished studies merit attention. Ferdmann and Feinschmidt 33show that white muscle of the rabbit and fowl contains more creatine-phosphoric acid than mixed or red muscle. In white muscle thephosphagen accounts for 30% of the total creatine, but this per-centage is much less in the case of red muscle. These workers findtraces of the substance in smooth muscle ; it is also said to be presentin the spleen, testes, uterus, stomach, and hemt but is absent fromthe kidney.Palladin and Epelbaum 34 find that the white muscle(biceps femoris) of the guinea-pig is richer in creatinephosphoricacid, creatine, and lactacidogen than the red muscle (M. semi-tendinosus). The latter workers corroborate the statement ofFerdmann and Feinschmidt regarding the higher percentage ofcombined creatine in white muscle as compared with red muscle.In a series of papers by Meyerhof and Lohmann35 the study ofphosphagen is materially advanced. In the first place, in additionto the original phosphagen (creatinephosphoric acid) a new guani-dinophosphoric acid (the generic name suggested by Meyerhof forphosphagens) has been isolated. This is argininephosphoric acidand it appears to participate in the chemical mechanisms of crus-tacean muscle in a manner similar to that of creatinephosphoric acidin vertebrate muscle.The barium salt of the new phosphagen has[.ID + 2" and the free acid [.ID + 5". It possesses a free a-amino-group, but it is not attacked by arginase. It is split into arginineand phosphoric acid on contraction of the muscle and is resynthesisedduring the aerobic recovery phase. The two phosphagens so fardiscovered are formulated as follows :HyPO(OH),q:NHTJHHSU;*PO(OH),q:NKI c %I3 q*CH,C02H ;jHNR, (iH2 C02HArgininephosphoric acid. Creatinephosphoric acid.The two more important papers from the Meyerhof laboratory,already referred to in the foregoing, deal with the physico-chemical32 Atti R.Accad. Lincei, 1928, 7, 70; A., 646.3s 2. physiol. Chem., 1928, 178, 173; A., 1393. 34 I b i d . , p . 178; A., 1393.35 Natumiss., 1928, 16, 47; A., 1277; Biochern. Z., 1928, 195, 22, 49; A.,917254 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.properties and physiological behaviour of the two phosphagem.It is shown that the enzymatic hydrolysis of creatinephosphoricacid in a muscle extract is adversely affected by carbohydrate andinhibited by fluoride. The rate of hydrolysis is dependent on thepH of the extract and has an optimum between pH 6.4 and 7.0.In fresh muscle extracts more alkaline than pa 8.0 a synthesis of thephosphagen occurs. The synthetic effect is increased by theaddition of creatine. Argininephosphoric acid shows a similarbehaviour in a qualitative sense, but, even at the neutral point, itstendency to be synthesised in the muscle extract is predominantand is maximal a t pH 8.0.Monoaminophosphoric acid, like thetwo phosphagens, is hydrolysed by muscle extract, a hydrolysiswhich is also inhibited by fluoride. The heats of hydrolysis and thedissociation curves of the two natural phosphagens and of amino-phosphoric acid have been carefully measured by Meyerhof andLohmann36 at acid and neutral reactions. It is shown that thehydrolysis of the phosphagens in the muscle in the vicinity of theneutral point involves hardly any alteration of the pH and thusthere is formed a strong buffer system from a system previouslydevoid of buffering power.A further publication from Meyerhof’s laboratory 37 deals withthe decomposition of creatinephosphoric acid in muscular activityand compares the extent of hydrolysis of the phosphagen with thelactic acid formation and with the tension developed in the muscle.In tetanus the hydrolysis of the phosphagen is the same for directas for indirect stimulation, but is markedly diminished in curarisedmuscle, whereas the lactic acid formation is the same under all threesets of conditions and varies only with the severity of tetanus.Inaddition to the aerobic resynthesis of creatinephosphoric acid firstdescribed by Eggleton and E g g l e t ~ n , ~ ~ Nachmansohn shows that ananaerobic resynthesis occurs immediately after relaxation, thatthis process is complete in about 20 seconds, and that it involves aresynthesis of some 30% of the hydrolysed phosphagen.Duringthis anaerobic resynthesis no lactic acid is formed, nor does anymuscle ammonia disappear, and it is concluded that the wholequestion of ammonia formation in muscle is not related to thepresence of creatinephosphoric acid. The anaerobic resynthesishas also been studied by Gorodissky 39 in the isolated frog’s muscle.In the first place, this worker confirms the observation of Eggletonand Eggleton 40 that short-period tetanic stimulation of the isolatedfrog’s gastrocnemius muscle decreases the creatinephosphoric acid36 LOC. cit.38 Arm. Report$, 1927, 24, 256.Nachmansohn, Biochem. Z., 1925, 195, 75; A,, 917.39 Z . phyeiol. Chern., 1928, 175, 261; A., 917.4o LOG. citBIOCHEMISTRY. 255and that this phase is followed during aerobic recovery by aresynthesis. After stimulation of longer duration (12 seconds) itis observed that resynthesis may occur anaerobically. Gorodisskydoes, however, find that resynthesis occurs more readily in thepresence than in the absence of oxygen, and after prolongedstimulation (25 seconds) it is only observed to occur under aerobicconditions.Further observations on the physiological behaviour of phosphagenare contributed by Eggleton and E g g l e t ~ n . ~ ~ They find that therate of disappearance of creatinephosphoric acid from a restingmuscle under anaerobiosis is much higher than the rate of lacticacid production. The decomposition of phosphagen in fatigue,rigor, or incubation in bicarbonate solutions, produces free creatinein amount corresponding to the creatinephosphoric acid which hasdisappeared.After being fatigued and subsequently exposed toox)-gen, the muscle resynthesises phosphagen very rapidly, thisprclcess being much more rapid than the corresponding resynthesisof glycogen from lactic acid. Under resting anaerobic conditionsthe phosphagen lost by the muscle is completely accounted for bythe inorganic phosphoric acid produced, but in activity part of thephosphoric acid enters into organic ester combination. Whenthe muscle is incubated in the presence of sodium fluoride, all thephosphoric acid is converted into the organic ester form. Eggletonand Eggleton are of the opinion that the phosphate radical ofphosphagen is made use of by the muscle, when stimulated toactivity or when incubated in the presence of fluoride, to esterifysome organic compound.In reference to this question one maymention here that Ferdmann 42 has found t’hat, for the formation oflactacidogen in vitro from the inorganic phosphoric acid of musclepulp, the presence of creatinephosphoric acid is not necessary. Itwould seem that incubation in the presence of fluoride must leadto the formation of fructosediphosphoric acid, first isolated frommuscle by Embden and Zimrnermar~n,~~ and since this compoundhas not been detected in fresh muscle untreated with fluoride, itdoes not appear that the esters formed under conditions of normalactivity and under the influence of fluoride can be the same.Nonethe less Eggleton and Eggleton conclude that the phosphoric esterproduced in activity, and whose formation ia deduced from anincreased acid-soluble organic phosphorus figure, is the same asEmbden’s lactacidogen, since the former is rapidly hydrolysed bythe muscle enzymes when the chopped muscle is incubated in a‘1 J . Ph@oZ., 1928,65, 16; A., 546.a Am%. Reports, 1927,M, 265.%. 23j6Y8b1. ChtWL, 1928,178, 52; A., 1267256 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.bicarbonate buffer. As these are the conditions under whichpyrophosphate is stated to be hydrolysed in muscle extracts, onehesitates to stress this question of the identity of the ester formed inactivity with lactacidogen.The muscle processes appear to be ofsuch a complex nature that at present it seems unwise to raise a tooelaborate superstructure of theory on data amassed purely bymethods of analysis carried out in what are admittedly complexmedia.From these observations which have been reviewed in some detailthere can now be no doubt that the reversible decomposition ofcreatine- or arginine-phosphoric acid is an integral part of themuscle activity, but as yet our knowledge is too fragmentary towarrant any statement concerning the exact function of thesephosphagens. One of the most recent suggestions advanced byMeyerhof and Nachmansohn 44 is that phosphagen is decomposedwholly or at least principally during excitation rather than duringcontraction of the muscle.It is shown that when the nerves areparalysed by tetramethylammonium chloride the decomposition isgreatly hindered, and resynthesis is rapid and complete on relax-ation. Furthermore an indirect confirmation of the associationbetween creatinephosphoric acid and excitation is afforded by theobservation that the excitability and phosphagen concentration ofa muscle are both increased by suspending the muscle in an in-organic phosphate solution of higher concentration than that presentin the muscle itself.Ammonia Formation in Muscle.During the past year much attention has been given to the questionof the traumatic or functional formation of ammonia in muscle, aphenomenon first observed by Parnas and Mozolowsbi.46 Alengthy and important series of papers 46 dealing with the questionof ammonia formation in muscle and of the relationship of adenylicacid to this process has just appeared from Embden's laboratory.These carry the question much further than 6he results of anyprevious investigator, but for the reason stated below 4' they mustbe reserved for review in a subsequent Report. Suggestive butsomewhat inconclusive experiments have been carried out byRosch and K a m ~ , ~ ~ who show that when the retina of the frog isNaturwiss., 1928, 16, 726; A,, 1277.Q5 Ann. Reports, 1921, 24, 257.48 8. phyeiol. Chern., 1928, l y e , parts 4, 6, and 6.*' The papers, which aro seven in number and occupy 162 pages of thojournal, appeared after this Report had been drafted. The Reporter hastherefore judged it advisable to reserve this important work for a subsequentReport rather than to incorporate it with undue brevity in the premnt, Report.48 Z.p h p i o l . C'fwm., 1928, 176, 158; A., 79%BIOCKEMISTRY. 257exposed to light a marked increase in ammonia occurs. E’resh oxretina pulp kept in 2% sodium bicarbonate solutiion a t 40” givesrise to the formation of ammonia by an enzymic process which israpid and complete in less khan two hours. The addition of guanylicacid to such retina pulps does not cause any notable increase in theammonia production, but on the other hand the addition of adenylicacid produces a marked increase, representing in some cases a yieldof goo/, of the amino-group present in this acid. It is, however,suggested that the evidence is against the precursor of ammoniabeing adenylic acid, a t least in the retina, since, after the pulp hasbeen treated with 1 yo hydrochloric acid, treatment which destroysthe ammonia-producing enzyme, no ammonia formation can bedetected on addition of an extract of muscle which has a powerfuldeaminising action on adenylic acid.None the less, despite theseinconclusive results obtained with the retina, the balance of theevidence at present available strongly suggests that adenylic acid isthe ammonia precursor of muscle, and indeed the new results fromEmbden’s laboratory would seem to prove this.That the ammonia formation in the muscle is subject to nervousinfluence is shown by Biittner.49 He finds that the traumaticformation of ammonia in frog’s muscle after section of the sym-pathetic nerves is some 50% higher than in the correspondingmuscles with the sympathetic nerve supply left intact.When thedenervated muscle is stimulated electrically, the ammonia formationmay be 60% higher than in the control muscle. On the other hand,the resting ammonia value is not regularly influenced by sympa-thectomy. Mozolowski and Lewinski 5O find that the formationof ammonia in frog’s muscle is much higher in summer than inwinter and presumably therefore bears some relationship to themetabolic state of the animal. In the muscles of the intact normalfrog the ammonia accumulated during work slowly decreases andthe resting value is strongly affected by the animal’s movements.The ammonia content of nervous tissue, unlike that of muscletissue, is not affected by pulping.In the curarised animal, stimul-ation of the nerves yields no increase in the ammonia of the muscle,but direct stimulation gives the same effect as in the non-curarisedanimal. 8odium fluoride diminishes ammonia formation in musclepulp, but it is without effect on the fresh, excised muscle, whichshows, with the onset of paralysis, the same ammonia formation asis produced by trauma, or heat or caffeine rigor.Chrzgszczewski and Mozolowski 51 have studied the course oftraumatic formation of lactic acid and ammonia in pulped muscle4n Biochem. Z., 1928, 198, 478; A., 1277.6O Ibid., 1928, 190, 388; A,, 196. 61 Ibid., 192S, 194, 233; A., 663.REP.-VOL. xxv.258 ANNUAL REPORTS ON THE PROGRESS OB CHEMISTRY.and find certain parallelisms. Thus when a muscle is maceratedwith sand and water the lactic acid formed in two minutes is tentimes the resting value and the course of formation is similar to thatof ammonia.. A borate solution of p , 9.3 inhibits both traumaticlactic acid and ammonia formation in the same manner. But sincesodium fluoride entirely abolishes lactic acid formation and onlymore or less diminishes the ammonia formation, it is concludeclthat .the two traumatic processes are not directly related to oneanother.Carbohydrate Jletabolism of Pathological Overgrowth.During the past few years Warburg and his co-workers havedevoted considerable attention to the mechanism of utilisatiou ofcarbohydrates by cancerous growths.Most of the numerouspapers which have appeared have been conveniently summarised byWarburg himself in two publications 52 and since the whole field ofinvestigation presents, apart from the intrinsic results obtained,certain interesting features of technique, it is judged appropriateto submit in the present Report a review of the problems encountered.The reader will find some reference to the earlier phases of theseinvestigations in the Report by Professor J. C. Drummond for1924.53 Warburg has shown from a study of Flexner-Jobling ratcarcinoma, Jensen rat sarcoma, and Rous hen sarcoma, as well asof tumours of human origin, that such cancerous growths resemblecertain yeasts in being able to metabolise carbohydrates by oxidative(respiratory) and glycolytio (fermentative) processes, Rut whilstnormal tissues under aerobic conditions make use almost exclusivelyof oxidative processes, they may under anaerobic conditions formlactic acid, thus exhibiting a glycolytic or fermentative function.Warburg has shown that a peculiarity of the cancer cell is its power,under aerobic conditions, of making use of both these processes inmetaboljsing carbohydrates.Isolated turnour cells, even in theentire absence of oxygen and for so long as they are supplied withglucose, may flourish for some time, utilising carbohydrate anaero-bically. Thus after 48 hours under the strictest anaerobiosis&us sarcomacells still flourished and could be transplanted aero-bically.Normal tissue cells from which the cancerous growths areformed do not exhibit such capacity to exist by purely glycolyticprocesses. Thus under comparable conditions excised intestinalmucous membrane forms only about one-tenth of the amount of62 “ ober den heutigen Stand des Carcinomproblems,” Berlin (JuliusSpringer), 1926, and “ Uber die katalytischen Wirkungen der lebendigenSubstanz,” BerIin (Julius Springer), 1928.59 Ann. Reporti?, 1924, 21, 208BIOCKEMTS’FRP. 259lactic acid formed by a carcinoma developed from the mucousmembrane. On the other hand the metabolism of the cells ofcertain embryos in a very early stage of development shows a muchgreater affinity to that of the cancer cell than does the adult tissuecell.For the st4udy of such problems in tissue metabolism Warburghas elaborated a manometric technique to which the followingconsiderations apply.Measurements are made of respiration, thatis, oxygen consumption (l), aerobic glycolysis (2), and anaerobicglycolysis (3), and these are expressed in the form of quotientssymholised respectively as Qol (l), Q!f (2), and QP (3), the value ofthe quotients being obtained by dividing the cubic millimetres ofoxygen consumed (l), the cubic rnillimetres of carbon dioxideevolved as a result of lactic acid formation in the presence ofoxygen (2), and the cubic millimetres of carbon dioxide evolved as aresult of lactic acid formation in the presence of nitrogen (3), eachby the dry weight in milligrams of the tissue used multiplied bythe duration of the observation in hours.The Meyerhof quotientmay then be calculated from :Anaerobic glycoly&- Aerobic glycolysis . 82) - Q3 , ~ e . , __I__ - _ _ _ ~ - - _____Respiration Qo,Assuming maxinium efficiency of the Pasteur reaction , whichcorrelates respiration with fermentation, the symbol U is used toindicate the excess fermentation, that is to say, the minimumtheoretical value for the aerobic glycolysis, or, making use of thesymbols already explained, U = Q.2 - 2Q,,. When the Pasteurreaction is maximal, U (the calculated excess aerobic fermentation)is identical with that found, The main lines of Warburg’swork suggest that the value U is positive for tumour tissue andnegative for normal tissue, varying between -39 and zero.Ex-ceptions are encountered in the case of the free-moving red andwhite cells of the blood, which show a positive U value, and of theretina cells, which show a greater glycolytic power than that of anyother animal tissue and, like cancer tissue, give positive U figures.Furthermore, in the case of retina cells the value of d&F/ldt ispositive, whereas it is negative for normal tissues and zero for tumourtissues. The following convenient summary of the general resultshas been given by Warburg and Kubowitz : 55Normal tissues Carcinomasexcept retina. and sarcomas. Retina. -Q$vz. it.. ................... 2 5 0 250>20 7 2 0 0dQ$ .................. <O 0 >O ........................ > O >O u 2 0-54 Warburg, Biochem.Z., 1927,184, 484. 6 5 Ibid., 1927, 180, 242260 ANNUAL REPORTS ON TF€E PROGRESS OF CHEMISTRY.An important extensioii of the observations which we have justdiscussed has been made by Crabtree 56 in a study of the carbo-hydrate metabolism of pathological overgrowths other than thoseof the malignant type so thoroughly investigated by Warburg andhis collaborators. The growths studied by Crabtree were those offowl-pox, vaccinia lesions in young chickens and in rabbits, andhuman warts. The fowl-pox lesions showed, in nearly every caseinvestigated, a positive excess fermentation making them fall intothe category of malignant tumours so far as their metabolism isconcerned. Vaccinia lesions in young chickens and human wartsalso exhibited a metabolism corresponding in type to that of malig-nant tissue, the magnitude of the respiration and the aerobic andanaerobic glycolysis approximating to that found for tumours.Inthe case of vaccinia lesions in rabbits the slight increase in t,hemetabolic activity observed is thought possibly to be due to theinvasion of the tissue by leucocytes, which show, as already men-tioned, a positive U value. The general conclusion arrived at byCrabtree is that the magnitude and relationships of the respiratoryand glycolytic processes, found by Warburg to be characteristic ofmalignant tissues, are shared in common with the latter by patho-logical overgrowths generally. A further interesting observationwas made by Crabtree in investigating the metabolism of Rouschicken sarcoma during development.The tumours were developedin the breast muscle, and during the first two days after the injectionof the cell-free filtrate used as inoculum, a slight increase in themetabolic activity of the muscle was noted. This was possibly dueto leucocytic invasion, since it was followed by a return to thenormal low values of the undisturbed muscle. Only when a histo-logical examination showed foci of tumour cells scattered throughthe muscle was any real increase found in the metabolism quotients.The figures obtained showed a rough correspondence in theirmagnitude to what might be theoretically calculated from theproportion of tumour tissue seen microscopically. It is concludedthat the tumour cells possess their characteristically high metabolicrate from the time of their appearance rather than that a progressivedevelopment of this metabolism takes place over a transitionalperiod.One must therefore infer that these peculiar metabolicphenomena are a result rather than the cause of pathological over-growths.The Chemistry of Internal Secretions.Thyroxine.-The important work of Harington and Barger onthe constitution and synthesis of thyroxine was fully dealt with in6 6 Biochem. J., 1928, 22, 1289BIOCHEMISTRY. 261an earlier Rep0rt.5~ This year there falls to be recorded the resolu-tion of dl-thyroxine by Harington.58 p-[3 : 5-Di-iodo-4-(4'-hydroxy-phenoxy)phenyl]-or-aminopropionic acid, to which the name 3 : 5-di-iodothyronine is given, was converted into its formyl derivative bywarming with formic acid.Attempts to resolve the formylderivative by means of alkaloid salts failed. Success was attainedby the use of Z-or-phenylethylamine and although the insolublefraction of the resulting salt mixture could not be obtained opticallypure, the soluble fraction, after two or three recrystallisations,showed no further change in rotation, the value being [a]5481 + 23.8'. On decomposition this salt yielded formyl-Z-3 : 5-di-iodothyronine, [a]5462 + 27.8", from which was obtained onhydrolysis with 15% hydrobromic acid 1-3 : 5-di-iodothyronine,[a]5461 1 1.3". The last-mentioned compound was then iodinatedwith iodme in ammoniacal solution to give Z-thyroxine, [a]5461 -3.2".A similar series of experiments carried out with d-a-phenylethylamineyielded in succession a soluble salt having [a]5461 - 21*9", formyl-d-3 : 5-di-iodothyronineY [a]5461 - 26.9", d-3 : 5-di-iodothyronine, [a]546l + 1-15", and finally d-thyroxine having [a]6461 f.2-97'. The possi-bility of racemisation during the final iodmation process wasexcluded by an experiment in which Z-tyrosine was iodinated, theresulting 3 : 5-di-iodotyrosine reduced to tyrosine, and the lattershown to possess its original rotation. In physiological testsZ-thyroxine was found to possess some three times the activity ofd-thyroxine. This new achievement is a noteworthy addition toHarington's previous brilliant work in this field.Insulin.-The work of Abel and his co-workers, of Funk, and ofclu Vigneaud on the crystallisation of insulin was dealt with in lastyear's Rep0rt.5~ The work described there has been continuedby du Vigneaud and his collaborators.6o Conditions for preparingcrystalline insulin from the impure product have been standardised,and amongst the amino-acids isolated from the crystalline materialafter hydrolysis are cystine, tyrosine, arginine, histidine, leucine, andlysine.From a comparison of the total sulphur content of insulinwith the amount of cystine present it is concluded that some sulphurcompound other than cystine is present in the insulin molecule. Astudy of the nitrogen distribution in crystalline insulin has also beenmade .61 Du Vigneaud, Geiling, and Eddy 62 bring forward evidenceb8 Report of the Meeting of the Biochemical Society (Dec.14th), J. SOC.m Ann. Repom, 1927,24, 201.60 J . Phuwn. Exp. Ther., 1928, 32, 367, 387; A,, 553.6 1 Wintersteiner, du Vigneaud, and Jensen, ibid., p. 397; A,, 653.62 Ibid., 1928, 33, 497; A., 1160.Ann. Reporta, 1926, 23, 234.Chem. Ind., 1928, 47, 1346262 BNNUAL REPORTS ON THE PROGRESS OB OHEMISTRY.which considerably strengthens the view that the crystalline materialis homogeneous. For instance, when crystalline insulin is adsorbedfrom N/lOO-hydrochloric acid by charcoal, and subsequently elutedwith phenol, no change in activity is noted. Nor does the adsorbedmaterial exhibit any differential solubility in disodium hydrogenphosphate solution. Moreover, the charcoal-phenol powder hasbeen reconverted into crystalline insulin.When crystalline insulinis heated with NjlO-hydrochloric acid at 100" for one hour, aprecipitate forms which is insoluble in dilute acid and in disodiumhydrogen phosphate solution. It dissolves in alkali and from theresulting solution there is obtained on acidification a producthaving the original solubility in acid and showing but slight loss ofactivity .Jensen and Geiling63 have succeeded in acetylating insulin bytreating it with acetic anhydride at 0" for 15 hours. The productshows some 4.5% of acetyl groups. It is hydrolysed very rapidlyby N/lOO-alkali at 0" and insulin is regenerated. The activityfigures of these preparations are of great interest. They were asfollows : for the original crystalline insulin, 45 units/mg.; foracetylinsulin, 8 units/mg.; and for the material regenerated byalkali treatment, 25 units/mg.Freudenberg and Dirscherl 64 hawobtained results of a somewhat similar nature. Insulin precipitatedfrom methyl alcohol by benzene was treated in pyridine at 0" withacetic anhydride for 3 hours and the resulting acetyl product, whichwas almost inactive, contained 3 4 % of the acetyl group. Treat-ment with O.03N-alkali at 1-3" for 24 hours gave a regeneratedproduct with one-third to one-fifth of the activity of insulin. Theregenerated product still contained O.SyO of acetyl groups. It isinferred that if insulin is a single substance acetylation probablyaffects hydroxy-, amino-, and imino-groups and of the resultingcombinations only the acetoxy-groups are hydrolysed by dilutealkali.The main point of difference between the results of Freuden-berg and Dirscherl and those of Jensen and Geiling lies in the muchlower activity of the product regenerated by the former workers ascompared with that of the latter workers. Jensen and Geiling 65find that the lowered activity of the regenerated insulin is probablydue to the loss of hydrogen sulphide, since even dilute sodiumhydroxide solution eliminates some sulphur from acetylinsulin,whereas the original insulin is unaffected by treatment with thesame concentration of alkali for 15 hours a t 0". It is suggested,therefore, that the lower activity of "reudenberg and Dirscherl'sregenerated insulin is most probably due to the greater amount ofJ .Plmm. Exp. They., 1928, 33, 511; A,, 1160.6Q 2. physiol. Chem., 1928, 175, 1; A., 676. 0 5 L O C . C i t BIOCHEMISTRY. 263decomposition which occurs with the more concentrated alkali usedby them.The Liver Constituent curative of Pernicious Anamia.-During thepast two years an important advance in medicine has been achievedon the basis of the demonstration by =not and Murphy 66 that incases of pernicious ansmia the feeding of large amounts of liveris followed by an increase in the red blood cell count. From thisobservation there has been built up one of the most remarkablysuccessful curative treatments credited to modern medicine. Thecurative effect is produced by some substance or substances presentin normal mammalian liver and presumably lacking in the systemsof sufferers from pernicious anEmia.The nature of the curativeagent is at present unknown and the Reporter, in including areference to this advance in the present section of this Report, doesnot wish to commit himself to the view that it is of the nature of aninternal secretory product. None the less, its properties aresuggestive of this, and in any case the term internal secretion issufficiently wide to support the argument from convenience forincluding the reference here. Methods of investigating the potencyof the various chemical fractions obtained from liver are basednecessarily on feeding experiments carried out on cases of perniciousantemia in the human subject, since it has not yet been demonstratedthat the typical clinical picture of the disease is manifested inexperimental animals.So successful has the cure proved that theR,eporter is given to understand that a lack of patients is seriouslyhampering further investigations into the nature of the curativeagent, surely a remarkable and unforeseen contingency !Cohn, Minot, Alles, and Salter 67 have published an account of thepreparation and properties of the active material obtained from liver.The latter was minced and brought to pn 5.0 by the addition ofsulphuric acid and the subsequent extraction ensured efficientremoval of the water-soluble substances in which the active materialis found. Coagulable protein was removed and t8he extract wasconcentrated under reduced pressure.The addition of alcohol tothe resulting solutJion to produce a concentration of 70% gave aprecipitate which was rejected, and the filtrate was again concen-trated and poured into sufficient alcohol to produce a concentrationof 95%. The aqueous solution of the resulting precipitate wascIeared with basic lead acetate and, after removal of excess of lead,t!reated with phosphotungstic acid. The solut<ion of the materialobtained from the phosphotungstate precipitate was rich in theactive substance. From the above method of concentration some66 J . Amer. Med. A~soc., 1926, 87, 470; 1927, 89, 769.4' J . Biol. C h m . , 1928, 77, 326; A,, 790264 ANNUBL REPORTS OR THE PROGRESS OF CHEMISTRY.idea will be gained of its nature. It is soluble in water and insolublein ether and alcohol.Active preparations have been obtained freefrom proteins, carbohydrates, lipoids, and iron, and of the best ofthese preparations doses of 0.6 gram per day (calculated as ash-freeorganic matter) exercised a definite physiological effect. Theactive material contained, on an ash-free basis, about 19% ofnitrogen. It seems to the Reporter that its properties, so far as theyare known, are not incompatible with those of a salt of a fairlycomplex organic acid.UnsaponiJiable Constituents of Animal Oils and Fats.I n recent years considerable attention has been given to thenature of the constituents of fish liver oils. The stimulus tosuch studies has been in part the chemical investigation of theunsaponifiable fraction of oils and fats containing vitamins-A and -D,but the field has intrinsic attractions of its own and provides aremarkably interesting chapter in animal biochemistry.I n thisfield much of the earlier work, which stands to the credit of Japaneseinvestigators, notably Tsujimota and Toyama, has been conveni-ently reviewed by Heilbron.68Prominent amongst the constituents of the unsaponifiable fractionof most elasmobranch fish liver oils are three alcohols, batyl, selachyl,and chimyl. With these are found a hydrocarbon, squalene, whichalone sometimes comprises some 80% of the oil, and cholesterol.The two first-mentioned alcohols are the subject of a recent com-munication by Heilbron and Owens.69 They assign to batylalcohol the formula C21H4403, which is one of the alternatives firstsuggested by the Japanese investigators already mentioned.It is asaturated dihydric alcohol and the main question concerning itsconstitution has centred round the nature of the third oxygen atom.Weidemann 70 was of the opinion that this was present as a methoxylgroup, but Heilbron and Owens now show that the action of hydriodicacid on the alcohol is to liberate octadecyl iodide, and they concludethat the parent alcohol is a monoglyceryl ether of octadecyl alcoholhaving the constitution C,8H37*O*CH2*CH( OH)*CH,*OH orC~8H3,*0.CH(CH2eoH)2. From the known analogies between thisalcohol and selachyl and chimyl alcohols, the former, which has theformula C2,H& and is the olefinic analogue of batyl alcohol, mustbe the monoglyceryl oleyl ether, and chimyl alcohol, C19H4003, themonoglyceryl cetyl ether.The occurrence of such glyceryl ethersin nature, forming a link between the fats and waxes, is a matter of68 Report of the Food Investigation Board, 1927, Section G.89 J . , 1928, 942; A., 616. 70 Biochem. J . , 1926, u), 686; A,, 1926, 980BTOCBEMISTRV. 265great biological interest, the inter-relationships of the three typesof compound being expressed as follows :Fat (R*CO*O),C,H,Wax R*CO-OR’Ethers R’O*C3H,( OH),Squalene, the hydrocarbon already mentioned, is an open-chaindihydrotriterpene with the formula C30H50 and the question of itsconstitution was dealt with in the Report of last year.71 Fromthe nature of the products isolated from the oxidation by means ofozone of squalene and of an incompletely hydrogenated squalenecorresponding to a decahydrosqualene, Heilbron 72 now considersthe main problem of the constitution of this hydrocarbon to beelucidated.Its formation can be visualised as the “ head to tail ”linking of six isoprene nuclei and it is probably synthesised in theliving organism by aldol condensations of aliphatic plant terpenealdehydes such as citral (C,,H,,O), citronella1 (C,,H,,O), or farnesal(C,,H,,O), followed by reduction in the animal liver.Interesting data concerning the unsaponifiable matter from thestomach oil of an elasmobranch fish, Scymnorhinus lichia, have beenreported by Karnrn.’, The unsaponifiable matter from this oilproved to consist mainly of squalene (98%) associated with 0.28%of batyl alcohol and 0.96y0 of a residue consisting chiefly of selachylalcohol.The oil, of which the function in the stomach is unknown,is therefore similar in nature to the liver oil of elasmobranchsgenerally. The problem of the biological significance of these un-saponifiable constituents of oils is being studied by Channon. Inthe case of fiuh it is found that the elasmobranch liver oilsdiffer from those of the teleosts in containing much larger amountsof unsaponifiable matter, and in the elasmobranch oils the higherthe percentage of unsaponifiable matter in a given oil the lower isthe sterol content of that fraction. This low percentage of sterolis not due to the presence of squalene as such but to the quantity inwhich it is present, for the relationship between sterol and theunsaponifiable fraction is maintained throughout whether squaleneis present or not.No evidence is therefore obtained of any relation-ship between sterol and squalene. None the less the question of theorigin of this curious hydrocarbon is an interesting one. Channonadduces evidence which suggests that it must be synthesised by theanimal and not derived from its foodstuff-a view which is inagreement with Heilbron’s speculations already referred to.Ann. Rcporl.s, 1925, 24, 137.Biocheni. J . , 1928, 22, 77; A,, 319.72 LOLL cil.74 Ibid., p. 51 ; A., 3 l g .I 266 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The Vitamins.Vitamin-A.-Following on the subject matter dealt with in thepreceding section of this Report it is judged advisable to give someaccount of recent chemical studies of the vitamin-A fraction ofcertain liver oils carried out by Drummond and Baker.75 Thatportion of the unsaponifiable fraction of cod-liver oil in whichvitamin4 is found is known to consist of unsaturated alcohols ofhigh molecular weight.Efforts to prepare from it crystallinephthalates or substituted phthalates were not successful, nor couldsnysatisfactoryfractionation be obtained on distilling the cholesterol-free material at vety low pressures. Considerable loss of thevitamin occurred. The unsaturated substances present in thevitamin fraction proved to be resistant to hydrogenation, thussupporting the view that they have a complex ring structure of thetype of the unsaturated sterols and higher terpenes.Comparativestudies were then instituted between the unsaponifiable fractions ofliver oils from different animals and possessing different vitamin4contents. Those selected were cod-liver oil, sheep-liver fat, Japaneseand Greenland shark-liver oils having the relative vitamin activities13 : 21 : 6 : 1. The fraction from sheep-liver fat contains, inaddition to cholesterol, a relatively large quantity of an un-saturated hydrocarbon which is not squalene but which resemblesthat described by Channon and M a ~ ~ i a n . ~ ~ Attempts to distil theunsaponifiable material from sheep-liver fat proved to be a completefailure: the hydrocarbon decomposed and only about 15% ofthe vitamin was recovered.Better results were obtained from thershark-liver oils. In the case of the Greenland shark oil, whichcontained less vitamin-A than the Japanese oil, the more solidfraction was almost devoid of vitamin-A and consisted of a mixtureof cholesterol and chimyl alcohol. The liquid fraction gave agood distillation curve indicating that it consisted largely of one ortwo substances. Hydrogenation of this fraction gave large amountsof octadecyl and batyl alcohols, which were formed respectivelyfrom the oleyl and selachyl alcohols of the original distilled material.Squalene was also present but only in traces. The Japanese oil,although much richer than the Greenland oil in vitamin-A, gave anunsaponifiable fraction of similar composition.Chimyl alcoholand cholesterol were obtained and by hydrogenating the distillationproducts of the sterol-free material an almost quantitative yield ofbatyl alcohol was obtained. Some 40% of the vitamin survived theReport of the Meeting of the Biochemical Society (Dec. 14th), J . SOC.Chem. Ind., 1828, 47, 1346.78 Biochem. J., 1926, 20, 409; A,, 1926, 638BIOCHEMISTRY. 267distillation of this material. From these results it is estimated thatof the unsaponifiable matter of these two shark-liver oils a t least95% has been separated in the form of identifiable substances whichare not believed to be related either directly or indirectly t o vitamin-A . The evidence suggests that the latter, like vitamin-D, is a sterolderivative present in liver oils in extremely low concentrations, andDrummond and Baker come to the disappointing but inevitableconclusion that the direct chemical attack on vitamin4 is virtuallyuseless.Improvements in the methods available for the detection andassay of vitamin-A have received considerable attention.Humeand Smith 77 have studied the evaluation of vitamin-A by means ofgrowth curves of rats. The technique used involved a depletionperiod during which D was supplied by ultra-violet irradiation.Graded amounts of A were then administered in the form of spinach,daily doses of from 0.2 to 1.0 gram being given, and the conclusionsarrived at are as follows : (a) With no dose or a very small dosethere is no recovery. ( b ) With small doses there is sub-normalgrowth graded quantitatively to the dose and followed by a prematureslackening.(c) With larger doses there is normal growth for a time,followed by premature slackening. (d) With an optimal dose thereis normal growth to maturity. It is suggested that the evaluationof A is best made by dispensing with the depletion period, or if it isused, by employing only doses which are likely to give the responses(a) and ( b ) . With regard to the foregoing suggestions Coward andKey 78 point out that such responses as those obtained by Hume andSmith have also been observed by them, but on the other handcertain substances containing vitamin-A give sub-normal growthgraded to the close but not followed by any premature slackening.Thus the rate of growth has been observed to remain unaltered andsub-normal for unusually long periods, some of the rats used attain-ing maturity only after about 40 weeks on the experimental diet.The importance of a long test of eight or more weeks is emphasised.Sherman and Burtis 79 point out that the greater the weight ofthe test animal the less is its gain in weight with a given intake ofvitamin-A and it is considered best to adhere to an eight-weekperiod for the test and to a standard weekly gain in weight of 3grams.Shortening of the test period tends to give variable andhigher results for the vitamin-A content of the material under test,and a higher standard rate of gain of weight decreases the delicacyof the method without increasing its accuracy.The specific arsenic and antimony trichloride colour tests for77 Biochent. J., 1928, 22, 504; A,, 555.7B J.Biol. Chem., 1928, 78, 671; A., 1161.78 Ibid., p. 1019; A., 1068268 ANNUAL REPORTS ON THE PROQRESS OF OHEMISTRY.vitamin-A have also received considerable attention during the pastyear. Steudel and Peiser 80 cast some doubt on the specificity ofthe antimony chloride reaction and state that a whale oil examinedby them gave the colour reaction when diluted in chloroform inconcentrations of 2 and 0.2%, whereas similar dilutions of the oilin a vitamin-free hardened vegetable oil failed to relieve the con-dition of rats kept on a diet lacking in A. These conclusions arediametrically opposed to those of earlier workers and therefore meritfurther attention, bearing in mind the fact that, although manycases of parallelism between the intensity of the colour reaction andthe vitamin-A potency have been observed, rigid proof of a directrelationship between the two is still lacking.The evidence isadmittedly strong but circumstantial. Wokes 81 has made a carefulinvestigation of the fairly permanent colours given by the usualreagents with sterols and their derivatives, and compared themwith the transient colours ascribed to vitamin-A. The latter havealso been investigated spectroscopically. It is found that irradi-ation of the sterols tends to make the colours more transient and onthe other hand a physiologically tested cod-liver oil was found togive with antimony chloride a ‘‘ vitamin ” blue which it was foundpossible to make persist for nearly an hour.One characteristicproperty of the “ vitamin ” colour is the sequence of the changefrom blue to red. With the sterols the characteristic change isred + blue and possibly red again. It has, however, been possibleto get a blue --+ red reaction from cholesterol irradiated at itsmelting point or oxidised under given conditions with certain re-agents including benzoyl peroxide. A somewhat similar observ-ation has been made by Rosenheim,82 but the chromogen so pro-duced was shown to differ from the “vitamin” chromogen. I nhis spectroscopic investigations Wokes has shown that the colourobtained with oils containing vitamin-A , when tested with arsenicchloride, shows bands at about 587 and 475 vp and with antimonytrichloride at about 614 and 530 pp.I n each case the maximumabsorption shifts from the band of longer wave-length to the shorterone when the chromogen is left in contact with the reagents, thechange corresponding to the blue --+ red transition.The possibility of developing still another method for detectingvitamind is suggested by the observations of Morton and Heil-bron,83 who conclude from a spectroscopic examination of variousoils and other preparations that the presence of the vitamin ischaracterised by an absorption band in the ultra-violet with amaximum at 328 pp. It is also suggested that one of the decom-2. phy8iOl. Chem., 1928, 174, 191; A., 925.Biochem. J . , 1928, 22, 830, 997; A., 800, 1058.82 Ann.Reports, 1927,24, 243. Biochem. J., 1928, 22, 987; A., 1068BIOCHEMISTRY. 269position products of the vitamin has an absorption band near 275to 285 pp.An extremely interesting observation regarding the formation ofvitamin-A has been made by Moore,a who finds that etiolated wheatshoots, fed to rats under conditions involving the minimum of redlight illumination consistent with the feeding and handling of theanimals, are an efficient aource of vitamin-A. It is concluded thatlight is not essential during any stage of the formation of the vitaminfrom the seed, or alternatively, if light is required, extremely shortexposures to dim red light are effective.Variations in the stability of vitamin-A from various plantsources are described by Sherman, Quinn, Day, and Miller.85 Forinstance, when tomato juice was heated at 97" in an atmosphere ofnitrogen for four hours, 17% of the vitamin was destroyed and thisrate was not affected by changing the pH of the juice from its naturalvalue of 4.2 to 9-2.Similar treatment in olive oil solution of thevitamin extract from dry spinach and from butter fat resulted in adestruction of 20% and 33% respectively. Steudel 86 had pre-viously reported that the vitamin-A of brain tissue is very sensitiveto heat except when dissolved with its lipoid complement in fat orother suitable medium.The B Vitamimx-The multiple nature of what was formerlycalled vitamin-B was dealt with in the Report of last year 87 andmuch work published since goes to corroborate and extend thisdiscovery. The evidence in favour of the dual nature of thisvitamin complex is strengthened by fresh data brought forward byKennedy and Palmer,8* Salmon, Guerrant, and Hays,89 Evans andBurr,g0 Chick and R o s c o ~ , ~ ~ Hunt,92 Hogan and Hunter,93 Hunt andKrau~s,~* and by Levene.95 Indeed a more complex tripartitenature is suggested in the investigations of Williams and Waterman 96and of Hunt.97 One of the most interesting results obtained from achemical point of view is that of Levene,g* who has shown that bydeaminising with nitrous acid an Osborne and Wakeman yeastconcentrate, and subsequently treating it with a silica gel, theadsorbate contains only the heat-labile vitamin-B,. Daily dosesof 0.07 mg.of this material were sufficient to maintain the normalBiochem. J., 1928, 22, 1097; A,, 1058.as J. Biol. Chem., 1928, 78, 293; A,, 1058.86 2. physiol. Chem., 1927, 170, 13; A,, 1928, 92.a 7 Ann. Reports, 1927, 24, 244.@II Ibid., 1928, 77, 231; A,, 676.9a J . Biol. Chem., 1922, 78, 83; A,, 926.g4 Ibid., 1928, 79, 733; A., 1405.ss Ibid., 1928, 78, 311; A., 1058. *' Ibid., 1928, 79, 723; A., 1406.J . Biol. Chem., 1928, 76, 591; A,, 555. Ibid., p. 487; A., 556.s1 Biochem. J . , 1928, 22, 790; A., 800.g3 Ibid., p. 433; A., 1069.g5 Ibid., p. 465; A., 1405.sa LOC. cit270 ANNUAL REPORTS ON TEFE PROGRESS OF CHEMISTRY.growth of white rats. One must assume that vitamin-B, is in-activated through loss of amino-groups. Kinnersley and Peters,90in continuing their studies on vitamin-B, of yeast, have succeeded inobtaining concentrated preparations curative of polyneuritis inpigeons in daily doses of 0.027 mg.They find that t,he solubilityof the vitamin in alcohol varies with the activity of the preparationand with the p , of the solution treated with the alcohol. It is notsoluble in chloroform, carbon tetrachloride, ether, acetone, or ethylacetate. This observation corrects certain erroneous statementswhich have gained some currency in the literature. There are certainsuggestions in the work described by Kinnersley and Peters that inthe aqueous extract of yeast vitamin-B1 may occur in two forms.In regard to the question of the possible tripartite nature of“ vitamin-B ” two independent but very similar investigations byWilliams and Waterman 1 and by Hunt2 are of interest.In thefirst-mentioned paper it is shown that pigeons kept on a syntheticdiet in which adequate supplies of purified B, and B, fractions werepresent, showed a marked improvement when air-dried brewer’syeast was added to the diet. B, was supplied as a fuller’s earthadsorbate of a dialysed yeast extract, and Bz as autoclavedyeast. In the second investigation the two fractions were alsoseparated by means of fuller’s earth and, although they were foundto supplement each other in maintaining the growth of rats, theyfailed to produce so good an effect as an equivalent amount offresh yeast. In both instances the presence of a third accessoryfood constituent in yeast is deduced in order to explain these results.Vitumin-C.-In last year’s Report attention was directed to theinteresting discovery by Zilva that the antiscorbutic activity ofdecitrated lemon juice is associated with a capacity for reducingphenolindophenol to its leuco-base, and in a further communicationthe investigation of this relationship is continued. When phenol-indophenol is added to decitrated lemon juice until the indicatoris no longer reduced, and the solution is adjusted immediately topH 7, the antiscorbutic activity disappears within 24 hours.Puri-fied antiscorbutic fractions from lemon juice lose their activitymuch more rapidly than does decitrated lemon juice of similaractivity. Decitrated lemon juice, dialysed in collodion thimbles ofa permeability which leaves the solution inactive after 3 days,loses the capacity for reducing phenolindophenol.This reducingcapacity is retained t o a great extent by the juice when dialysed inthimbles of a permeability which yields an active juice at the end ofthe dialysis. Acidity retards deterioration on storage of the anti-scorbutic activity in anaerobically autoclaved decitrated lemon juice.Biochem. J., 1928, 22, 410; A,, 566. L O C . C i t . . = L O G . Cit.Biochem. J., 2928, 22, 779; A,, 801. 8 Ann. Reports, 1927, 24, 247B I0 CHEMISTRY. 27 1On storage a t 2ia 3, however, the deteriorating effect of autoclavingis scarcely perceptible. Lemon juice autoclaved anaerobically, evenin a very acid medium, deteriorates much more rapidly a t pE 7 onstorage than similar solutions which have not been autoclaved.Comparatively little loss occurs in decitrated lemon juice which hasbeen autoclaved at 40 lb.pressure for 1 hour under strictly anaerobicconditions. These results would seem to justify Zilva’s earliersuggestion that the stability of the antiscorbutic vitamin in Iemonjuice is conditioned by the presence of a reducing principle and ofanother constituent, the functioning of which is destroyed by heat.Vitamin-D and Ergosterol.-Much important work falls to bereviewed in this section of the Report. Dealing first with thequestion of the specificity of ergosterol as the substance from whichvitamin-D is formed by irradiation, attention is directed to a carefulresume of the position by Rosenheim and Web~ter.~ The charao-teristic general features of the sterol structure are the presence inthe molecule of a hydroxyl group, of one or more unsaturatedlinkages, and of a system of four reduced rings. The question of thepart played by the hydroxyl group in the activation process isdifficult to decide.Rosenheim and Webster had already shownthat two esters of ergosterol, the acetate and the benzoate, arerendered by irradiation as highly antirachitic as the sterol itself,and more recently von Euler, von Euler, and Rydbom have madea similar observation with regard to diergosteryl phosphate, whichwhen irradiated is powerfully antirachitic and promotes growth inrats in doses of 0.0002 mg.per day. Such activation may, however,be preceded by a photochemical hydrolysis and, as Rosenheim andWebster point out, it is not yet possible to determine experimentallythe bearing of the hydroxyl group on the question of activation.On the other hand, it is clear that not only the presence but thenumber of double bonds is a deciding factor in the photochemicalproduction of vitamin-D. The naturally occurring saturated sterolscoprosterol and a-amyrol and the artificially reduced sterols di-hydrocholesterol and dihydrositosterol all remain inactive afterirradiation. Moreover, neither cholesterol nor sitosterol with onedouble bond, nor stigmasterol, cholesterylene, oxycholesterylene,and dihydroergosterol (Windaus and Brunken 8, with two doublebonds can be activated.The slight activity noted by Hess andAnderson9 in irradiated sitosterol is without doubt due to slightadmixture with ergosterol, and a similar explanation accounts forthe activity observed by Jendrassik and KemBnyffi lo in cholesterolMature, 1928, 121, 670; A., 567; Biochem. J . , 1928, 22, 762; A,, 801.Lancet, 1927, ii, 622.Annalen, 1928, 460, 225; A,, 424.Biochem. Z., 1928, 199, 276; A., 1406.* Ann. Repo7t9, 1927, 24, 260.lo Ibid., p. 249272 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.irradiated after bromine purification, since Bills, Honeywell, andMacNair 11 find that ergosterol is not entirely removed fromcholesterol by bromination or by treatment with charcoal, some 3%still remaining. There can therefore be little doubt that of thecompounds mentioned above ergosterol and its esters alone giverise on irradiation to the vitamin. Rosenheim and Webster havealso shown that isoergosterol, which is obtained from ergosterolhydrochloride by the removal of hydrogen chloride, cannot beactivated, and another isomeride, neoergosterol, likewise remainsinactive (Windaus and Borgeaud 12).Very recently Rosenheim andWebster l3 have shown that fungisterol, which accompanies ergo-sterol in ergot, and two other sterols from the same source remainbiologically inactive after irradiation, and Hume, Smith, andSmedley-MacLean l4 have made a similar observation regarding azymosterol (from yeast). Oxidation equally with reduction destroysthe capacity of ergosterol to form the vitamin, since Windaus andBrunken l5 have demonstrated the inactivity of irradiated ergosterolperoxide.On the other hand, ergosterol regenerated from theperoxide can be activated. It is of interest to note in passing thatthe peroxide is prepared from ergosterol by photo-oxidation in95% alcohol solution in the presence of eosin and under the in-fluence of the visible radiations of a powerful filament lamp. Fromthe foregoing results and others, which need not be detailed here,one has every confidence in concluding that ergosterol alone of allthe numerous pure substances examined possesses the property offorming vitamin-D under the influence of ultra-violet light.Much important work has appeared during the past year on theultra-violet absorption spectrum of ergosterol and its irradiatedproducts. A careful investigation of this question has been made byWebster and Bourdillon.16 They find that ergosterol examinedafter short periods of irradiation shows an increase in absorption,which is a t a maximum after a period depending on the concentrationof the solution and the intensity of radiation. On further irradiationthe absorption decreases steadily to almost complete disappearance.The antirachitic effect and the absorption are produced at approxim-ately the same rate.On further irradiation of the active products,after the removal of ergosterol, the antirachitic activity and theabsorption decrease and eventually disappear after irradiation forthree to five hours. It is deduced that the irradiation of ergosterol11 J .BioZ. Chem., 1928, 78, 251; A., 332.12 AnnaEen, 1928, 480, 235; A., 425.Report of the Meeting of the Biochemical Society (Dec. lQth), J . SOC.Chem. I n d . , 1928, 47, 1348.l4 Biochem. J., 1928, 22, 980; A,, 1059. l6 LOC. cit.l 6 Ibid., p. 1223; A., 1228BIOCHEMISTRY. 273probably produces two substances in succession, one with a maximumabsorption a t 280 or 290 pp, which is probably the vitamin, and asecond with a maximum a t about 230 pp. In relation to this ques-tion an interesting hypothesis has been suggested by van Wijk andReerink.17 It is that ergosterol has two systems of absorptionbands connected with different parts of the molecule. By irradiationsuch that vitamin-D is formed the first system with maxima a t 293,281, and 270 pp (see also Heilbron, Kamm, and Morton 18) makesway for the characteristic absorption band of isoergosterol at a littlebelow 250 pp, which would mean that the corresponding part of themolecule undergoes the same change in constitution by irradiationas by the transformation of ergosterol into isoergosterol by thechemical method of Reindel, Walter, and Rauch.19 Another partof the molecule obviously does not change its constitution, which isdeduced from the permanence of the second system of bands a t 262and 250 pp. Like vitamin-D, isoergosterol remains unchanged byirradiation with ultra-violet light of wave-length longer than270 pp and is destroyed by light of wave-length of about 250 pp, asis shown by the disappearance of the absorption bands. Recentlypublished results of Bills, Honeywell, and Cox 2o substantiallycorroborate these suggestions in that it is shown that the photo-chemical product which shows an absorption maximum a t 248 ppis not vitamin-D, for the appearance of this band coincides, not withthe development, but with the destruction of antirachitic potency.The last-mentioned workers further suggest that, although oxidationprocesses play no part in the formation of vitamin-D, they appearto be a t least one cause of the destruction of the substance with aband a t 248 pp. The latter is supposed to be a substance having amolecular configuration similar to that of isoergosterol. VanStolk, Dureuil, and Heudebert 2 l find that an alcoholic solution ofpure ergosterol shows absorption maxima a t 293.2, 281.5, 270.0,and 260.0 pp. Irradiation by the light of a mercury vapour lampfrom which all radiations shorter than 255-0 pp have been screenedproduces a very slow formation of the vitamin. Irradiation by thetotal light of a hydrogen lamp in an atmosphere of nitrogen resultsin the disappearance of the first three bands, an increase in theintensity of the fourth, and the appearance of bands a t 250-3 and240.5 pp.Bills and Brickwedde 22 have stated that cholesterol (impure)can be activated by ultra-violet light at a temperature of -183",and a more detailed account of similar experiments on ergosteroll8 Biochem. J . , 1927, 21, 1279; A., 1928, 92.20 J . Biol. Ghem., 1928,80,557.At the same time vitamin-D is formed in quantity.l7 Nature, 1928, 122, 648.ID Annalen, 1927,452,34; A., 1927,241.21 Compt. rend., 1928, 187, 854; A., 1406.22 Nature, 1928, 121, 452 ; A., 657274 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.has been given by Webster and B~urdillon,~~ who have investigatedthe effects of temperatures ranging from +77.8" to -195" on therate of activation of the sterol. The observed lack of marked effectof changes of temperature between 3-78' and -18" on the reactionof activation shows that the temperature coefficients of the changescausing production and destruction of the vitamin are not widelydifferent, and the very moderate effect of lowering the temperatureto -180" suggests that the temperature coefficient of both reactionsis very small and hence that both reactions are directly photochemicalin nature.Interesting speculations have been published by Fosbinder,Daniels, and Steenb~ck,~~ Kon, Daniels, and Steenbock,2s andCoward26 regarding the minimum dose of vitamin-D which iscapable of being detected physiologically. In the first -mentionedinvestigation the energy absorbed by cholesterol during activationby means of monochromatic light of wave-length 265 pp is measuredwith accuracy. It is found that the minimum time of irradiationrequired to produce a positive effect in the " line " calcification testis 22.5 seconds, during which time the energy absorbed is 234 ergs.The number of quanta absorbed is calculated as 3.2 xApplying Einstein's law of photochemistry, this would imply that3.2 x 1013 molecules of vitamin-D had been synthesised and,assuming the molecular weight of the vitamin to be approximatelythe same as that of the sterol, from the number of gram-moleculesproduced (5 x l O - l l ) , the weight of vitamin-D generated in thisexperiment was calculated as 5 x x 385 = 2 x lo-* gram.This was not a daily dose but the whole dose required during thetest period of ten days. In the second investigation mentionedabove, similar considerations are applied to ergosterol and from thisbasis the minimum detectable amount of the vitamin is estimated6 x 10-8 gram. Using a standard solution of irradiated ergosterol,lWss Coward finds that 2 x loe5 mg. is the minimal daily doseproducing a positive result in Steenbock's methods of assay. Thiscorresponds to a consumption of 2 x lo-' gram in 10 days. Assum-ing that rather less than 10% of the irradiated ergosterol is vitamin-D, a conclusion based on the results of Rosenheim and Webster,27the amount of the vitamin present in the latter quantity would be2 x 10-8 gram. These various results seem to be remarkablyconcordant and one has every confidence that they give a fairlyaccurate measure of the potency of vitamin-D.A. C. CI~IBNALL.JOHN PRYDE.24 J . Amer. Chem. SOL, 1928, 50, 923; A,, 657. z3 LOG. cit.25 Ibid., p. 2573; A., 1288.z 6 Biockm. J., 1928, 22, 1221; A., 1288. 2' L O C . cit

ISSN:0365-6217    

DOI:10.1039/AR9282500222

出版商:RSC    

年代:1928

数据来源: RSC

摘要:

CRYSTALLOGRAPHY‘’ AN Introduction to Crystal Analysis,” by Sir William Bragg,lis founded on a course of lectures a t the University College,Aberystwyth, given in 1926. It is primarily intended for readerswhose main interests lie in other branches of science, but who wishto understand the principles of analysis and its possible applications.The book will be welcome as a non-technical and readable accountof all branches of the subject. (‘ Strukturbestimmung mit Rontgen-interferenzen ” by H. Ott adds to the increasing list of books onX-ray analysis. All working in this branch of science will find thebook of interest for its thorough treatment and inclusion of themost recent results.‘‘ Materialpriifung mit Rontgenstrahlen ” by R. Glocker is devotedto the technique of all methods of studying materials with X-rays.It contains an interesting section dealing with the determinationof crystal structure, size, orientation, and deformation, and withcrystal chemistry, and the structure of alloys.It is of importanceto those concerned with the technical application of X-ray analysis.Crystal Physics.One of the most interesting, and, a t the same time, one of themost difficult tasks of crystallography is to link up the knownphysical properties of real crystals with their structures as deter-mined from X-ray measurements. The quantitative agreementbetween the calculated and the observed values of most of thephysical constants of crystals is, at the present time, very poor.This is no doubt due largely to the fact that the mathematician dealsin his calculations with an ideally regular crystal Iattice, whereasthese do not as a rule occur in nature, even in the so-called singlecrystals.The imperfections of the lattice are of two main kinds-large-scale imperfections, due to the fact that almost all crystalsconsist of a number of smaller fragments whose orientations,although nearly the same, differ slightly ; and small-scale imper-fections due to irregularities, probably extending over only a fewatoms, in the lattice itself. These minute irregularities have beenG. Bell & Sons.2 ‘‘ Handbuch der ExperimentaIphysik,” Bd. 7, Akad. Verlagsges., Leipzig276 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.studied by A. SmekalY3 who identifies them with the centres of thephosphoresence which many real crystals show.Certain crystals,notably the alkali halides, become coloured when exposed to lightof suitable wave-length. Smekal points out that, in such minute“ scars ” in an ionic lattice, electrons will be released from theanions, by the action of light, more easily than in the lattice as awhole. He attributes the coloration to the release of an electronfrom an anion, and its subsequent combination with a neighbouringkation to form a coloured neutral ion. The irregularities areuniformly distributed, and about one atom in 10,000 appears to beaffected in the average crystal. A crystal under mechanical stresswill yield at such points of weakness first of all, and once yieldinghas begun, it will be followed by a breakdown of the structure.The mechanical strength of the crystal will thus be much less thanwould have been expected from the lattice structure alone.The question of crystal perfection and its relation to physicalproperties was also dealt with by C .H. Desch in a paper intro-ductory to a discussion on Cohesion and Related Problems, held bythe Faraday Society in November 1927. J. E. Lennard-Jones and(Miss) B. M. Dent,5 in the course of the same discussion, read apaper on Cohesion at a Crystal Surface. They considered theattractive force on a charged ion near a (100) face of an ionic crystalof the rock-salt type. This force can be considered as made upof four parts : (1) the direct electrostatic attraction of the chargeon the ion by the valency charges of the ions of the crystal, (2) thea.ttraction between these ions and the dipole produced by thepolarisation of the attracted ion by the field near the surface,(3) the force due to the polarisation of the surface ions by theattracted ion, and (4) the force of attraction known to exist betweenneutral atoms, which is conveniently termed the van der Waalsattraction. It is shown that, although at very small distancesfrom the surface the electrostatic forces are much greater than thevan der Waals attraction, a t greater distances the latter pre-dominates, so that it acts as the first agent in the adsorption ofatoms or ions at a crystal surface, the electrostatic forces serving tocomplete the final capture.Intimately connected with this subject is the question of crystalgrowth, which has been studied recently by W.Kossel,6 from thetheoretical side, and by K. Spangenberg and his co-workers, from8 See a summary by A. Smekal, “ Ueber den Aufbau der Realkristalle,”Atti del Congress0 Internationale dei Fisici, Como, 1927. (Volta Centenary.)Trans. Faraday SOC., 1927,24, 63; A., 1928, 111.Ibid., p. 92; A., 1928, 8.Nachr. Qes. W&78. G6ttingen (Math.-Phys. KE.), 1927 136.Neue Jahrb. Min., B.-Bd., 1927, 67, 1197CRYSTALLOGRAPHY. 27'7the experimental side. Kossel considers a crystal of the sodiumchloride type built up layer by layer, parallel to the cube face.Any given layer is supposed to be built up row by row, and thecase is considered of a partly completed layer, resting upon a numberof completed ones, which consists of a number of completed rowsand one incomplete row.Suppose a new ion is to be added to thestructure. It may go to the completed surface so as to start anew layer, it may start a new row immediately beside one alreadybegun, or it may continue the incomplete row. It can be shownthat the greatest amount of energy is gained by continuing a rowalready in existence; next comes the starting of a new row, andlast of all, some way behind, the starting of a new layer. Thusthere is a marked tendency for a partly-formed cube face to com-plete itself before a new layer is begun, so that the crystal willgrow with plane faces, and the cube form will be much the mostprobable.The actual rate of growth of crystal faces in directions per-pendicular to themselves has been measured by K.Spangenberg(Zoc. cit.), and by A. Neuhaus,* by a method due originally toD. N. Artemje~,~ in which a sphere, turned from a single crystalof rock-salt, is suspended in a solution of the same salt, and allowedeither to grow, or to dissolve slowly, according to whether thesolution is sligbtly supersaturated, or slightly unsaturated. Greatcare has to be taken to keep the concentration of the solution con-stant. The sphere slowly develops faces, ultimately becoming abeautifully regular polyhedron, and the rate of growth of thedifferent faces is compared. With pure sodium chloride solution,the velocities are in the order v110>v2~'210>~ll~>vloo, correspondingto a tendency for the actual faces to develop in the order (loo),(111), (ZIO), (110).If the solution contains a small quantity ofurea, however, the order of velocities is vllo>vloo>vlll, correspond-ing to a tendency for the (111) face to grow a t the expense of theothers.The average amplitude of the thermal vibrations, and hence theforces between the atoms, in a crystal lattice may be studied bymeasuring the variation with temperature of the intensity ofreflexion of X-rays by the crystal. An important quantity inX-ray measurements is the atomic scattering factor-usually denotedby F , which is the ratio of the amplitude of the radiation scatteredby an atom in a given direction, under the conditions considered,to that scattered in the same direction by a single classically scatter-ing electron; F approaches the number of electrons in the atomfor small angles of scattering, but falls off in value rapidly with2. Kriat., 1928, 68, 16, Ibid., 1918, 48, 426278 AXNUA.IJ REPORTS ON THE PROffRESS OF OHEMISTRY.increasing angle, owing to the interference of the waves scatteredfrom different parts of the atom.The peater the volume, there-fore, which is occupied by the average atom, the more rapidly doesF fall off with increasing angle: it will thus fall off much morerapidly at high temperatures than at low ones, since this volumeis greater the greater the amplitude of vibration of the atoms.Suppose that 2 is the mean-square amplitude of vibration ofthe atoms of the kind considered, perpendicular to a set of planesin a crystal at which reflexion of X-rays, of mave-length 1, is takingplace at a glancing angle 0.Then it has been shown lo, 11 that,if F,, is the scattering factor of an atom in a state of rest, and Fthe value for the average atom under the conditions considered,F = Foe-2f, where M = 8tc2sin20. G / h 2 . The value of 2 depends,of course, on the interatomic forces, but for certain simple crystalsit is possible to calculate it in terms of the elastic constants, andhence, by measuring the dependence of F on temperature, both tocheck the formula and to estimate the amplitudes of the atomicvibrations.Measurements of P for a series of spectra from rock-salt l2 andsylvine13 (KCl) at temperatures ranging from about 86" Abs.to900" Abs. have shown a very good agreement between the observedvalues of M and those calculated by Waller, from the lowesttemperatures used up to about 500" Abs. At higher temperatures,the intensity of reflexion decreases much more rapidly than theorypredicts, but this is to be expected, since the theory is only validfor small amplitudes of vibration. It is really the difference in Ma t two temperatures which is determined from the ratio of the Pvalues at those temperatures, and it is this difference which isfound to agree closely with the values calculated from the elasticconstants. If the crystal possesses energy of vibration at theabsolute zero, this will correspond to a constant addition to M ,which is proportional to the vibrational energy, and this of coursecannot be determined from the ratio of P at two temperatures.The new quantum mechanics definitely requires the lattice topossess half a quantum of vibrational energy per degree of freedoma t the absolute zero, and, if we assume this amount to be present,we can calculate the actual values of M from the experimentalresults, and hence the amplitudes of vibration.l* Furthermore, itis then possible to calculate from the observed values of Po, the10 P.Debye, Ann. Physilc., 1914, 43, 49.11 I. Waller, Dissertation, Upsala, 1925.la R. W. James and (Miss) E. M. Firth, Proc. Roy. Soc., 1927, [ A ] , 117, 62 ;lS R. W. James and 0;. W. Brindley, ibid., 1928, [ A ] , 121, 165,I* I.Waller and R. W. James, ibid., 1927, [ A ] , 117, 214; A,, 1928, 112.A., 1928, 226CRYSTALLOGRAPHY. 279values of F for the atoms in a state of rest. Now it will be evidentthat, if we can calculate the values of F,, theoretically, we may,by comparing them with those obtained from the experiments,obtain definite information as to the existence of zero-point energy.D. R. Hartree 15 has devised a method for calculating the Schrsd-inger charge-density distribution, ++, for ions such as Na', Cl',and K', and it has been shown by Waller that, if this distributio~iis treated as scattering classically, the correct values of F, art:obtained. The values of Fo calculated in this way for Na', Cl',and K' agree remarkably closely with those obtained experi-mentally, and the existence of zero-point energy in rock-salt andsylvine is clearly indicated.16 The difference between the valuesof F with and without the correction for zero-point energy is con-Biderable, and should be outside the range of experimental error.The actual values of the root-mean-square amplitude at 17" for thecrystals studied are : in KCl, both atoms 0.25 A.; in NaCl, Na0.22 A., C1, 0-24 A.The amplitudes of the vibrations at the zero-point are of the order of 0.1 A. for both crystals.Experiments of the type just considered have a definite bearingon the problem of determining the structure of the more complexcrystals. Unless one is content with the formal determination ofthe space-group, which is now a nearly mechanical operation, it isnecessary to be able to calculate the amount of radiation scatteredin different directions by any assumed arrangement of atoms, inorder that this can be compatred with that actually measured bythe spectrometer, or photographic plate. We have in fact aquantitative problem in X-ray optics.The units in terms of whichall such calculations must be made are the F factors for the differentatoms in the crystal. Experiments on simple crystals such assodium or potassium chloride show that the quantitative methodsrest on a sure foundation, and give one confidence in applying themto more complex cases.lTThe question of the application of quantitative methods to theanalysis of complex crystals has been discussed in detail by W. L.Bragg and J.West.18 They show that quite a rough absoluteestimate of F for a large number of spectra leads, even in quitecomplex cases, to a determination of the parameters of the struc-ture. Working values of the P factors are given for a number ofatoms. These are based on a method of calculation due to L. H.Thomit~,1~ which, although only approximate, gives results in close15 Proc. Camb. Phil. SOC.~ 1928, 24, 89, 111; A., 216.16 R. W. James, I. Waller, and D. R. Hartree, Proc. Roy. Soc., 1928, [A], 118,l8 2. Krist., 1928, 69, 118.18 Proc. Cumb. Phil. SOC., 1927, 23, 642; A., 1927, 290.331; A., 462. Compare W. L. Bragg, Solvay Conference Report, 1927280 ANNUAL REPORTS ON THE PRO~RBSS OF CHEMISTRY.enough agreement with those calculated by Hartree to be used incrystal analysis. It must be borne in mind that the intensities ofhigh-order spectra are exceedingly sensitive to small changes inthe atomic positions, so that a comparatively rough value of Psuffices to fix these with great accuracy.The important thing isthat the F values, even if rough, should be absolute values. Thereare, of course, many difficulties yet to be overcome, particularlythose due to the influence of the state of perfection of the crystalon the intensity of reflexion. In this connexion, reference shouldbe made to a very interesting study of the reflexion of X-rays bydiamond,20 and to a paper on the value of F for carbon.21There has been a tendency in some quarters to maintain that thelegitimate aspirations of X-ray crystallographers should not gobeyond the determination of the space-group.It seems difficultto defend this standpoint, and there is little doubt that the techniqueof crystal analysis is slowly reaching a state in which it will bepossible to work out the structures of really complex crystals.Crystal St~uctures : (1) Inorganic.Elements.-The structures of the two forms of manganese havebeen determined by G. D. Preston,22 from Laue photographs androtation photographs. The results obtained for a-manganese con-6rm the work of Bradley and Thewlis, reported last year. Thestructure of @-manganese is referred to in connexion with its iso-morphism with the alloy Ag,A1 (p. 300).An allotropic form of silver has been discovered by G. Allard,23which is obtained by the action of copper on a solution of silvernitrate ; it has an orthorhombic structure.The alkaline-earth metals have been investigated by G.L. Clark,A. J. King, and J. F. Hyde.24 Calcium has a face-centred cubicstructure, whilst that of barium is body-centred cubic. The structureof strontium is still uncertain, although F. Simon and E. Vohsen 25assign a face-centred cubic structure to this metal at the ordinarytemperature, and a hexagonal close-packed structure at highertemperatures.The structure of iodine has been investigated by P. 31. Harris,E. Mack (jun.), and F. C. Blake,26 and by A. Ferrari.27 The elemen-2o W. Ehrenberg, P. P. Ewald, and H. Mark, 2. Kriat., 1928, 66, 547.21 M. Ponte, Phil. Mag., 1927, 3, 195; A., 1927, 191.a2 Phil.Mag., 1928, 5, 1198, 1207; A., 820.Compt. rend., 1928, 187, 223; A., 940.24 Proc. Nat. Acad. Sci., 1928, 14, 617; A., 1177.26 F. Simon and E. Vohsen, 2. phgaikal. Chem., 1928, 133, 168; A., 694.J . dnaer. Chem. SOL, 1028, 50, 1583; A., 822.37 Atti R. Acad. Lilac&, 1927, 5, 582; A,, 1927, 611CRYSTALLOGRAPHY. 281tary cell is an orthogonal parallelepiped with orthorhombic-bipyram-idal symmetry, the space group being Vjf. There are eight atomsin the cell, which are grouped in molecules of I,, the distancebetween atomic centres being 2.70 A.Cmpound~.-In a crystal of ideal type, the unit crystalline cellcontains a definite number of atoms. A chemical analysis of sucha crystal shows that the law of constant multiple proportions isobeyed, and it is possible to assign to the crystal a formula inwhich integral numbers of atoms of various types are groupedtogether. The existence of such a formula has been generallyassumed in the X-ray analysis of crystals.It is becoming increas-ingly evident, however, that a cell containing the same integralnumbers of each type of atom throughout the crystal representsan ideal state of affairs, to which actual crystals may only approx-imate, and that wide departures from such a state may be toleratedwithout destroying the crystalline arrangement, especially in thecase of complex types. The deviations may be of a more com-plicated kind than the well-known partial replacement of atoms ofone kind by an equivalent number of atoms similar in chemicalnature, or than the replacement in the felspars of the pair Na + Siby the pair Ca + AI.An interesting case is that of the synthetic spinels examined byF.Rinne.28 Spinel, MgM,O,, crystallises in the cubic system.The magnesium atoms are surrounded by four oxygen atoms at thecorners of a tetrahedron, and the aluminium atoms by six oxygenatoms at the corners of an octahedron. These tetrahedra andoctahedra are linked together to build up the well-known spinelstructure, a classical type, fist analysed byW. H. Bragg and H. Nishi-kawa in 1915. Alumina, Al,03, crystallises in a very differentform, with rhombohedra1 symmetry. Yet the artificial spinelsmay be made with any proportion of MgO to Al,O, between 1 : 1(corresponding to the true spinel) and 1 : 5.The crystals show acontinuous variation with composition in refractive index anddensity, and all give almost identical Laue and powder X-rayphotographs of the spinel type. Rinne concludes that the resultsmay be explained by supposing that the crystals are isomorphousmixtures of spinel with y-Al,O,, a cubic form of alumina, and that;their structure maJy be represented formally as follows :Mgo*A1203 + ,(A100M203). MgO*Al,O, A10 N203This case is entirely parallel to the oxidation of magnetite, Fe,O,(with spinel structure), into a cubic form of Fe203, examined by** Neue Juhrb. Min., 1928, [ A ] , 58, 43282 LJT”AL REPORTS ON THE PROGRESS OF CHEMISTRY.0. Baudisch and L. A. W e l ~ , ~ ~ which gives X-ray photographsclosely similar to those of magnetite.Whatever the precise atomicarrangement may be, it is clear that the unit cells of the two com-pounds contain different numbers of atoms, and yet that themajority of these atoms are arranged in so similar a way that theX-ray patterns are almost indistinguishable, and a wide range ofmixed crystals can be formed. The average number of atoms inthe unit cell of the mixed crystal is not integral.In this connexion, it is interesting to discuss the case of siUimaniteand mullite. R. W. G. Wyckoff, J. W. Greig, and N. L. Bowen30found that powder, Laue, and single-crystal photographs werepractic-ally identical for the two compounds, and this was confirmed byJ. F. Hyslop and H. P. R o ~ k s b y , ~ ~ and by H.Mark and P. Ros-baud.32 The structure of these compounds has been examined byTV. H. Taylor,33 who sums up the experimental results as follows :(1) Two compounds of quite different composition, sillimanite,A12Si0,,(Al,03,Si02), and mufite, A1,Si,O1,,(3A1,0,,2Si0,), giveX-ray diffraction data which are almost but not quite identical.(2) The unit cell deduced in the usual way from the mullite data,contains only three-quarters of a molecule of mullite (4$Al,1@iY9$0,atoms).Taylor has attempted a, complete solution of the sillimanitestructure, the essential features of which are as follows. The unitcell contains four molecules of A12Si0,. One aluminium, &(I),and four oxygen atoms of each molecule are used up in formingstrings of octahedra, linked together by edges parallel to the c axis,The remaining aluminium, &(2), silicon, and oxygen atoms (oneof each) bind the strings together.The binding atoms Al(2) a,ndX i have almost identical a and b co-ordinates in the structure, andin the c direction they alternate a t intervals of approximately c/2.If the aluminium and silicon atoms are regarded as identical, thewhole structure repeats almost exactly at intervals of c/2. Hence,in the X-ray photographs, the true length of the c axis is onlyshown by certain very weak spots or lines, for A1 and Si diffractX-rays in a, very similar way. The fifth oxygen atom is placed sothat the arrangement of oxygen atoms around Al(2) is almostidentical with that around silicon.TO compare sillimanite and mullite, it must be noticed that the29 Naturwiss, 1926, 13j 749.See also Ber., 1928, 81, 2153, where S. €3.Hendriclcs and W. H. Albrecht discuss the parallel case of the oxidation ofCoO,Fe,O, t o Co20,,2Fe,08.30 Arner. J . Sci., 1926, 11, 469; A., 1926, 664.81 Trane. Soc. Glass T e c h . , 1926, 110, 412; B., 1027, 229.32 Neue Jahrb. Min., 1926, [ A ] , 54, 127,33 2. Xrist., 1928, 68, 603CRYSTALLOQRAPHY . 283sillimanite cell contains a group Al,Si,O,O. The mullite cell appearsat first sight to have identical a and b axes, but a c axis half aslong ; however, prolonged exposure in rotation photographs showsthat the c axes are also identical. The mullite cell thus outlinedcontains 16 molecules, i.e., N,Si,O,,I. 5-Ray data show clearlythat the structures are almost identical, and the arrangement ofsillimanite indicates the way in which they are related.Thepositions of Si and Al(2) are so alike that it is easy to understandthat one in four of the Si atoms can be replaced by Al, givingAl,Si, in place of Al,Si,. Simultaneously, one in every fortyoxygen atoms must be removed from the structure, but this wouldamppear to be tolerated without a radical alteration of the generalarrangement. The question of the real size of the mullite cell isleft open : to satisfy the formal requirements of space-group theoryi t must be a multiple of that outlined above.To sum up, these cases illustrate a form of isomorphism betweencompounds in which there is not a one-to-one correspondencebetween atoms in the formulae. Of course such isomorphism isindicated by many examples amongst minerals, but it is interestingto see how X-ray analysis is tackling the problem of discoveringwhat remains fixed and what is variable in a series of such com-pounds.The investigationof a series of sodium and calcium silicates by R.W. G. Wyckoffand G. W. Morey 34 was described in last year’s Report, Na,CaSiO,and Na,Ca( SiO,), being shown to have practically identical X-raydiffraction patterns. A very interesting series is that of the artificialultramarines, investigated by F. M. Jaeger 359 36 and his co-workers.They find for the natural compound nosean a cubic unit cell con-taining two molecules of Na,Al,Si,O &% Artificial ultramarines,with formulae approximating to Na,Al,Si60,,S, (blue), Na3A14Si60,,S,(red), and Na&@i60&& (green), all give X-ray powder photo-graphs almost identical with those of nosean.The mineral haiiyine,(Na,CaAl,Si,O1,S), also gives the same powder photographs. Onthe other hand, sodalite, Na4A13Si301,Cl, gives quite a differentpattern.A repetition by R. W. G. Wyckoff and S. B. Hendricks 37 of theanalysis of zircon, ZrSiO,, is of interest because the simplicity ofthe structure makes it possible to determine the situations of theOther interesting cases occur in the silicates.34 Amer. J . Sci., 1926, [v], 12, 419; A., 1927, 10.36 F. M. Jaeger, G. K. Westenbrink, and F. A. van Melle, Proc. I<. AEad.TVetensch. Amsterdam, 1927, 30, 249; A,, 1927, 716.F.IT. Jcleger and F. A. van Melle, ibid., p. S S 5 ; A,, 1928, 463.31 2. Krist., 1927, 86, 73; A,, 1928, 821284 BNNUAL ZEPORTS ON THE PROGRESS OF CHEMISTRY.oxygen atoms around the silicon atoms with high accuracy. Zircon-ium and silicon atoms are fixed in position by the symmetryrequirements of the tetragonal lattice. The accuracy estimatedfor the two parameters u and v determining the positions of theoxygen atoms is shown by the limits0.18<~<0*20 ; 0.32<~<0.34.The upper limits are estimated to be most probable. It followsfrom this, that oxygen atoms build a regular tetrahedron aroundthe silicon atoms with a silicon-oxygen distance of 1.64 8., and anoxygen-oxygen distance of 2.64 A. These results confirm those ofearlier observers.L. Vegard38 in 1926 found (in Wyckoff’s not-ation) zd = 0.190 and v = 0.306. Wyckoff states that his resultsdo not agree with those of Vegard, but the latter points out 39 thatthis apparent disagreement is due to a different choice of crystalaxes. W. B i d s 40 with the aid of spectrometer measurementsfound u = 0.212, v = 0-333.The structure of diopside*l throws light on the pyroxene-amphibole series of minerals. Diopside is a typical pyroxene. Themonoclinic cell contains four molecules of CaMg(SiO,),. Eachsilicon atom is surrounded by four oxygen atoms at the corners ofa regular tetrahedron, the average Si-0 distance being 1.61 8.One edge of the tetrahedron is nearly parallel to the c axis, and theoxygen atoms at each end of this edge are common to two tetra-hedra.The tetrahedral groups thus form a series of endless chainsparallel to the c axis of the crystal. These chains lie side by sideand are cemented together by the calcium and magnegium atoms.The three typical cleavages of the crystal are parallel to the chains,evidence of the relatively high strength of binding along the chains.This would appear to throw light on the structure of fibrousminerals such as asbestos (an amphibole) where the fibre directioncorresponds to the c axis of diopside.In a paper on the felspars, F. Machatschki 42 proposes a divisionof the silicates into three main types, which is novel and suggestive.It is known that oxygen atoms are grouped in fours around siliconand beryllium, probably also around boron and, in certain cases,aluminiuni. Machatschki considers the linking up of these tetra-hedral groups.In the orthosilicates proper (“ Ortho-typus ”), thereare separate tetrahedral groups enclosing silicon atoms, an examplebeing Mg,SiO,. It is supposed, on the other hand, that in thePhil. Mag., 1926, 1, 1161; A., 1926, 663.3Q Z. Krist., 1928, 67, 482.40 Min. Mag., 1926, 21, 176.41 B. Warren and W. L. Bragg, 2. Krist., 1928, 69, 168.42 Zentr. Min. Geol., 1928, [A], 3, 97; A., 1349CRYSTALLOGRAPHY. 285felspars (NaAlSi,O, ; CaAZ,Si,Os), aluminium as well as silicon liesbetween four oxygen atoms. There is one atom of silicon oraluminium to every two atoms of oxygen; hence a tetrahedralgroup must share each corner with a neighbouring group, just asin quartz, SiO,.He names this class the " Feldspat-typus," andremarks that all forms of SiO,, and the crystals beryl and phenacite,belong to it. (Beryl has the formula of a metasilicnte, and phen-acite that of an orthosilicate.) Finally, he supposes an intermediatetype (" Meta-typus ") to exist, in which the ratio of kations insidetetrahedra to anions is 1 : 3. In this case, the tetrahedra are linkedin chains, each group holding two oxygen atoms in common withits neighbours. It is interesting to note that this structure hasactually been discovered in diopside.two determination^^^^ 44 of the structure of topaz, [Al(F,OH)],SiO,,are in complete agreement as regards the general arrangement ofatoms.The structure is described by Alston and West as anarrangement of oxygen and fluorine atoms in closest packing. Itis interesting because the pa'cking is not either of the well-knowncubic or hexagonal forms, but has features common to both. Asimilar arrangement has been noticed by L. Pauling in the structureof brookite (see below). In all forms of closest packing, sheets ofoxygen atoms are packed one on top of the other, but whereas inthe hexagonal closest packing the third layer, and in the cubicclosest packing the fourth layer, repeats the position of the first,in this new type it is the fifth layer which does so. Silicon atomslie between four oxygen ions, and aluminium atoms between fouroxygen ions and two fluorine or hydroxyl ions. The positions ofall atoms in the structure were verified by direct X-ray analysis.An identical structure is arrived a t by Pauling, who bases hisarrangement on the general features of co-ordination compounds.*He develops an interesting method of investigating the structure ofthese compounds.The investigations of a number of workers haveshown that co-ordination compounds may be regarded as fabricscomposed of regular arrangements of the anions around the kations,the most common grouping being four anions at the corners of atetrahedron, or six a t the corners of an octahedron. In the silicatesin particular, the common groupings are those of four oxygen atomsaround Si and Be, possibly also B, and of six oxygen atoms aroundAl: either group occurs around such atoms as Mg or Fe.By a* The word " co-ordination ') is here used, in the sense common in X-rayanalysis, as designating an arrangement which may be regarded as 8 con-tinuous structure of oppositely charged ions.4a L. Pauling, Proc. &aft. Acad. Sci., 1928, 14, 603; A,, 1176.44 N. A. Alston and J. West, PTOC. Roy, Soc., 1928, [ A ] , 121, 358 ; 2. Krist.,1928, 69, 149286 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.sharing of oxygen atoms between groups, continuous structuresare built up, like fabrics of which tetrahedral and octahedral groupsare the individual stitches. Pauling uses this feature to suggestpossible structures for complex ionic compounds, and tests thepossibilities by X-ray analysis. For instance, in topaz, he assumest'hat aluminium is surrounded by six anions and silicon by fouranions, as in other silicates.He then treats these octahedral andtetrahedral groups as units, and, by trying various ways of fittingthem together, discovers one which has the same symmetry astopaz, a'nd which explains the main features of its X-ray diffractionpatterns.This method of investigating the structures of compounds hadpreviously been outlined by Pauling 45 in a paper on the structureof brookite, TiO,, which affords a very interesting example ofpolymorphism. The structures of rutile and anatase, other formsof TiO,, have been known for some time. In both cases the titan-ium atom is surrounded by six oxygen atoms at the corners of adistorted octahedron. Pauling assumes a similar arrangement ofthe oxygen atoms around the titanium atoms in brookite.Bytrying various ways of fitting the octahedra together, one is foundwhich appears to be the brookite structure. Each octahedronshares three edges with neighbouring octahedra. Eight octahedraare contained in the orthorhombic unit cell with the space group V;:,and the main features of the X-ray diffraction pattern are explained.The regarding of co-ordination compounds as composed of linkedtetrahedral and octahedral groups of anions is not novel; it is avery striking feature which has often been stressed in describingthese compounds. Pauling has, however, extended the ideafurther by considering both the nature of the linking (corner-,edge-, or face-shared) and the distortion from the regular form,and has developed a most promising method of investigating complexcrystals.A very interesting paper by W.H. Zachariasen46 forms one ofa series coming from Prof. V. &I. Goldschmidt's laboratory at Oslo.It deals with the whole series of sesquioxides and compounds ofthe type ABO,. The value of such surveys is considerable, becausethe ground is so completely covered. Most of the sesquioxidesbelong either to the corundum (A1,03) type or to a new type(C-type), of which Mn,03 is an example. The calcite, aragonite,and perowskite structures are repeated by many of the ABO,compounds. Special structures are found for AgNO,, RbNO,,KCIO,, HIO,, AgClO,, and are completely or partly analysed.45 L. Pauling and J.H. Sturdivant, 2. Krist., 1928, 68, 239413 NorsEe V;d. Akad., Oslo, 1928, No. 4CRYSTALLOGRAPHY. 287The structure of potassium dihydrogen phosphate has beenexamined by S. B. Hendri~ks.~~ The symmetry is tetragonal-scalenohedral. Potassium and phosphorus atoms are a t positionsfixed by symmetry, and oxygen atoms in positions fixed by threeco-ordinates, as reported by 0. H a s ~ e l . ~ ~ The positions of theoxygen atoms could only be fixed within rather wide limits(0.045 <~<0*075 ; 0.120 <y<O* 135 ; 0.145 <~<0*165).illlowing for the full variation of position within these limits,however, the assigned structure gives a tetrahedral arrangementof oxygen atoms which is much distorted from the regular form.The 0-0 distance in a group is between 1-92 and 2.20 a,, parallelto the plane (OOl), and is 2.62-2.81 if.along the other edges ofthe tetrahedron. This big distortion is significant, particularlywith regard to the possible influence of the hydrogen atoms, andraises an interesting point.An investigation of alum by L. Vegard and E. Esp49 links upwith a previous investigation by J. M. Cork.5* The positions oftho atoms (excluding hydrogen) are fixed by eleven parameters,and the structure is partially analysed. In agreement with previouswork, four molecules of KA1(S04),,12H20 are found in the unitcell, with symmetry Ti, and potassium and aluminium in the Nnand C1 positions of rock-salt. Vegard and Esp further find itposition for the sulphur atom which agrees with that found byCork, and suggest an orientation of the SO, group which corre-sponds with one alternative indicated by Cork’s results.Theauthors stress the speculative nature of their conclusions, andfurther work on this interesting structure is clearly necessary.Complex Salts.-As the study of the structure of complcs saltsproceeds, we see how essentially correct are the ideas of Werner onco-ordination, and those of V. M. Goldschmidt on the determin-ation of structures by the size and polarisation properties of theircomponent units (see Ann. Report, 1927, 24, 274). The structuresin all cases so far investigated are those where the ions of simplosalts have been replaced by complex (co-ordination) ions.This, in general, leads to high symmetry-in some cases even toa higher symmetry than that possessed by the complox ion itself.0.Hassel 51 has shown that not only are crystals of the pentammino-aquo-type, [Co(NH3),,H,0]I, or [ Co(NH,) 5,H20]( ClO,),, isomorphouswith those of the corresponding hexammino-compounds, [Co(NH,),]T,O 7 Amer. J. Sci., 1927, 14, 269; A, 1927, 1013.p0 2. Elektrochem., 1025, 31, 513; A., 1925, ii, 1130.48 Ann. Pkysik, 1928, 85, 1152; A,, 820.5u Phil. Mag., 1927, (vii), 4, 688; A., 1928, 6.G1 Nor8k. cfeol. Tidskr., 1928, 9, 33; 10, 92288 AXNWAL REPORTS ON THE PROGRESS OF OHEMISTRY.or [Co(NH3),](C10,), (see Report for 1927), but also that they havethe same cells, and are indistinguishable, except for a small changein the spacing. It is impossible for such a group as Co(NH,),,H,Oto have any form of cubic symmetry, so that there is a contradictionof the law that equivalent crystallographic positions must beoccupied by identical atoms.The contradiction is only apparent,for we may assume either that the cell is really much larger, in away undetectable by X-rays owing to the inappreciable differenceof scattering power between 0 and N, or that the CO(NH,)~,H,Ogroups take up all different orientations in a fortuitous manner,giving rise to what might be called a statistically symmetrical orself-mixed crystal. That there is no appreciable loss of symmetryis shown by the optical isotropy of the crystals. A similar state ofaffairs was shown to exist in the newly investigated series :which has a fluorite structure with Co(NH,),"' in the place of Ca**,and SO,'' and I' alternately in the place of 2F'.When the complex ion is more polarisable, there is the usualloss of symmetry.Thus K,Sn(OH),, investigated by R. W. G.Wy~koff,~, has a rhombohedral cell containing one molecule, andresembles the K,SnC1, structure compressed along one trigonalaxis. In K,Pt(SCN),, as S. B. Hendricks and H. E. Merwin 53have shown, the distortion is still greater and the structure resemblescadmium iodide rather than fluorite. Isomorphous structures werefound for the rubidium and ammonium salts. A similar loss ofsymmetry is produced by an unsymmetrical kation. In(CH,*NH,),SnCl, and ( C,H,*NH3),SnC16, investigated by Wyckoff ,54the former has a pseudocubic rhombohedra1 cell containing onemolecule, resembling (NH,),SnCI, but elongated along one trigonalaxis, and t,he latter has a hexagonal cell containing one moleculewith an anti-cadmium iodide structure, The full atomic para-meters have been determined in none of these cases, but theinteratomic distances are in accord with those of better-knowncrystals.Water of Crysihllisution.-Two interesting hydrated salts, lithiumchloride monohydrate and lithium iodide trihydrate, have been63 Amer.J . Sci., 1928, 15, 397; A,, 463.57 Ibid., p. 487; A,, 850.1J ibid., 1928, 16, 349; A., 1176; 2. Krzd., 1928, 68, 231CRY STALLOGRAPRY. 289investigated by 8. B. Hendricks.55 In neither case was an un-ambiguous structure found, on account of the small scattering ofthe Li ions, but the proposed structures are very plausible on othergrounds.LiCl,H,O is tetragonal with a pseudocubic cell, a = 3.83,c = 3.88 pi., with one molecule, and has a czsium chloride structure,the large Cs' ion being replaced by the complex LiOH,' ion, hydrogenatoms not being considered in the symmetry. LiI,3H20 is hexa-gonal : a = 7.45, c = 5.43 A. with two molecules in the cell, andis isostructural with triethylammonium iodide (see below), thecomplex Li(OH,),' replacing NHEt,'.Salts of the Substituted Amrnonias.--Our knowledge of these saltsis mainly due to the work of Wyckoff and Hendricks, which hasfurnished results of great theoretical importance. When groupsof higher alkyls are substituted in the ammonium radical, a con-tinuous transition of structure and properties between inorganicand organic crystals is observed.So far, the salts investigated fallinto three groups : (1) the symmetrical tetra-alkylammoniumsalts (NR,)X, where R is an alkyl radical and X a halogen, (2) themonoalkylammonium salt's (NH,R)X, and (3) the symmetricaltrialkylammonium salts (NHRJX.(1) Of these, tetramethylammonium iodide has been moststudied.56 Apart from the early investigations of Vegard, all theworkers agree as to the main details of the structure, a simpletetragonal cell a = 7-94 A., c = 5.75 A., space-group D;,, contain-ing two molecules. G. Greenwood found a different space group,Q,,, but this may be due to wrong indexing of planes; however,the class D H still remains a possibility.The structure is similarto that of phosphonium iodide, and is a distorted version of thatof ammonium chloride (casium chloride structure). The chlorideand bromide differ from the iodide only in having a slightly smallercell. The structure of tetraethylammonium iodide is much lesscertain, since the three different investigators 57 only agree as tothe cell, a = 8.85 A., c = 6.93 A., with two molecules, and theface-centred arrangement of the iodine atoms. The symmetryfound by Wyckoff is D,, while I. Nitta finds no symmetry planesin the Laue photographs, indicating an S4 symmetry. The differ-ences between these results show that i t is unsafe to draw fnr-5 5 Ibid., 1927, 66, 297; Amer. J . Sci., 1928, 15, 403; A., 694.L. Vegard, Phil.Mag., 1917, 33, 395; Vides. Akad. Oslo, 1926, S o . 10;G. Greenwood, Min. Mag., 1927, 21, 258; A., 1928, 108; R. W. G. Wyckoff,2. Krist., 1928, 67, 91; W. Zachariasen, N o ~ s k . Geol. Tidsskr., 1927, 10,No. 1 ; Chem. Zcntr., 1928, i, 1360; A., 940.57 G. Greenwood, loc. cit.; R. W. G. Wyckofi, 2. Krbt., 1928, 67, 5 5 0 ;I. Nitts, Proc. Imp. &4cad., Tokyo, 1928, 4, 292; A., 1079.BEP.-VOL. xxv. 2m ANNUAL REPORTS ON THE PROGRESS OF OHEMISTRY.reaching conclusions from them a t the present time. However,the structure is obviously of the anti sodium-chloride type.(2) The great majority of monoalkylammonium salts 58 are foundto conform to a tetragonal distorted sodium chloride, caesiumchloride, or anti sodium-chloride structure, as would be expectedwith a kation of increasing size.The cell dimensions are sbownin Table I. (The a axes corresponding to the pseuclo-cubic structureof the NaCl types are shown ; the true a axes are 1 of these.)TABLE I.Diff. per C:U. c. atom inSalt. /----A-. ,---.-- Structure. c-axis.NE,Cl 3.36 3.86 CsClNH41 7-58 7.58 CsClCH,.NH,Cl 4.28 5.13 CSCl 1.27CH,-NH,Br 7.10 8.7~5 NaClCH,*NH,I 7.24 8.95 NaCl 1.37IC,H,.NH,Br 4.63 6.24 8.32 86" 59' Monoclinic i______-_____________________L____________-----__"-.~-_----_-----..------_--------.1I I I 8./C,H,.NH,I 4-81 6-63 8.68 87" 64' $ 9 IC,H,.NH,Br 4.67 7.36 CSClC,H7'm,I 4.85 7.33 CSClC,H,.NH,Br 7.10 15-23 9 sC,Hl ,.NH,Br 7.09 16.95 $ ? 1-72C ,H 1 ,.NHsI 7.25 17-20 ? ? 1-90C,Hl,.NH3Br 6.96 19.78 2-83C.6 . a.12.27 C3H7*NH3C1 4.48 7.40 CSCI (1.14) = c)-______________^____________I____________-----_-_---_---___---------------~-----.dC4H,.NH,CI 7.10 14-85 Anti-NaCIC4H,,-NH,I 7.33 15.30 9 ) C,H 11.NH3C1 7.09 16.69 9s 1-84C 6H13*NH$1 7.05 19.55 2-86C ,H ,, -NH J 7.29 19.54 2.34C,Hl,*NH,Cl 7-02 21.09 1-54C,Hl,*NH31 7-3 1 21-14 1.60Apart from the beautiful manner in which this series demonstratesthe ideas of ionic dimensions, the chief interest lies in the latter halfof the table, where all the salts have the same anti sodium-chloriclcstructure. Here it can be seen that the c-axis increases progres-sively, although apparently by very different steps, with eachadditional carbon atom, and it is plain that the general directionof the carbon chain lies along the c-axis.This raises a very im-portant point. If the cell and space group are correct, theonly possible positions for the carbon atoms are along tetrad axes,implying a straight carbon chain with a mean distance C-C of1.3 A. On the other hand, in all other compounds a G-C distanceof 1.4-1.55 8. has been found, and there is the strongest evidencefor zigzag chains in the higher paraffins (see below). Hendricks'assertion that the chain must be straight conflicts with a large bodyof other evidence, and the question whether it necessarily follows6 8 S. J3. Hendricks, 8. Xrist., 1928, 67, 106, 119, 465; 68, 189CRY STALLOBRAPHY. 291from his data must be examined. The carbon chain can be provedstraight only if (a) the crystal is tetragonal, ( b ) the crystal is ideallyand not statistically symmetrical (see above ; complex salts), and(c) the cell size is correctly known.Of these conditions the firsttwo are on general principles the easiest to verify, but to establishthe third would require much more refined methods. Hendrickshimself states that in estimating intensities the contributions ofthe carbon atoms can be neglected. A fortiori intensities, and withthem the cell and space-group derived from the absence of reflexionsfrom planes of multiple spacing, cannot be used to fix the carbonatom positions. The weak additional spots, and small changes inintensity of the observed spots due to a zigzag carbon chain, couldprobably only be detected by careful ionisation spectrometer work.The evidence so far may be said to confirm the arrangement ofcarbon atoms in rows in the shorter aliphatic chains, but not todetermine their detailed structure.(3) Triethylammonium chloride 59 has a hexagonal cell a=8.38 d.,c = 7.74 8., space group Ci,, with two NH(C2H,),C1 molecules.The three ethyl groups are arranged almost in a plane, with thenitrogen atom in the centre.Each halogen atom is surrounded bythree triethylammonium groups in the same plane, and by oneabove and below, and vice versa for the ammonium group, formingan interesting 5-5 co-ordination arrangement (as mentioned above,this is also the structure of LiI,3H20).Cry~tal Structures : (2) Organic Compounds.I n the past year, the three main problems in the crystal structureof organic compounds, vix., the symmetry of the carbon atom, thenature of the aliphatic chain, and that of the aromatic ring, havebeen brought almost to the point of solution.Symmetry of the Carbon Atom.-The controversy, alluded t o inlast year’s Report, between the advocates of a pyramidal and thoseof a tetrahedral bisphenoidal arrangement of the four substitutedgroups around a carbon atom has been satisfactorily settled infavour of the latter, all pyramidal arrangements so far suggestedhaving proved to be of a bisphenoidal nature.The careful crys-tallographic work of H. Seifert,6* and the researches of A. Hettichand A. Scheede into pyro- and piezo-electrical properties, haveshown that the symmetry of pentaerythritol itself is most probablySa, and that the apparent electrical polarity is simply due to the60 Sitzungsber.Preuss. Akad. B’ise. Berlin, 1927, 289; A., 1928, 351.S. B. Hendricka, 2. Krist., 1928, 67, 472.u1 2. Phy8ik, 1927, 48, 147; A., 1928, 361292 ~ N U A L REPORTS ON THHI PROGRESS OF CIHBMISTRY.absence of a centre of symmetry. Pentaerythritol tetra-acetateand tetranitrate were investigated by A. Gerstacker, H. Moller,and A. Reis,62 using a Weissenberg moving-film camera, whichseparates very beautifully the reflexions of planes which might beconfused on an ordinary rotation photograph. The tetra-acetate,C(CH2*O*OC*CH,)4, warns found to have a tetragonal cell, a = 12.34 pi.,c = 666 8., with two molecules, and was assigned the space groupC$,, which left the possibility of a pyramidal C4 molecule.Thisconclusion, however, was disproved by (Miss) I. E. K n a g g ~ , ~ ~ whoshowed that the (001) reffexion previously found was spurious, andthat the true space group was Cis, giving a bisphenoidal molecularsymmetry S4 ; and her interpretation was subsequently acceptedby the original authors. The tetranitrate, C(CH,*NO,),, has atetragonal cell a = 9.45 A., c = 6.74 Hi., space group D.$, withtwo molecules, giving a molecular symmetry 8,.The structure of several ethane substitution productls has beencarefully studied by Mrs. Lonsdale (Miss K. Yardley).G4 All areof low symmetry, and the success of the investigation dependedon the use of intensities measured by the ionisation spectrometer,rather than on the purely photographic methods which have beenused with most organic crystals.The first isomorphous seriesinvestigated contained the substances C2C16, C2Br6, C2C14Br, (twoforms), C,Br,F,C,Cl,Br, and C,Br,(CH,), (two forms, one obtainedbelow 0"). All have orthorhombic cells (a = 10&--12.0, b = 10.1-10.9, c = 6.4-6.7 A.), space group V;:, with four molecules. Eachmolecule has one plane of symmetry passing through the twocarbon atoms, and a pseudo-symmetry centre. Less completedeterminations were made of the tetragonal forms CMeBr2*CMeBr2and CMe,Br*CMe,Br, and of the pseudo-tetragonal tertiary alcoholCMe,*CMe,-OH. The cell dimensions of the first two are a =8.81 A., c = 11.27 A., and a = 10.45 8., c = 8.14 pi., respectively,each containing four molecules.It can be seen that the crystalsthough isostructural are by no means isomorphous. In bothcrystals the substituent atoms or radicals arrange themselves inan octahedron about the two central carbon atoms, i t being im-possible to determine the relative positions of these in the molecule.These difficulties are essentially similar to those encountered indealing with the substituted ammonias (see above).The whole question of the crystallographic and other evidencefor the spatial distribution of the valencies of the carbon atom isfiilly discussed by Mrs. I(. Lonsdale 05 in a paper entitled " Evidence6s Nature, 1928, 121, 616; A., 464. 6z 2. Kriht., 1928, 66, 355; A,, 1177.ed (Miss) K. Yardley, PTOC.Roy. SOC., 1928, [ A ] , 118, 449, 486 ; A., 576.66 Phil. Mag., 1928, 6, 433; A., 1079CRYSTALLOGRAPHY. 293of the Anisotropy of the Carbon Atom.’’ She concludes that thecarbon atom has two different types of valency, denoted by A andBy and associated conjecturally with the electron orbits (2,)and (2J. A C-C bond is always formed of an A valency from oneatom with a B valency from the other. I n this way she explainsthe structures of diamond, graphite, the ethane derivatives, and thebenzene ring. As expounded in this paper, the idea of A and Bvalencies, though very suggestive, will not meet the rigid require-ments of the recent application of the wave mechanics to chemicalcombination as developed by W. Heitler and F. London.6s Itmay, however, be possible to restate Mrs.Lonsdale’s ideas interms of wave mechanics while conserving their undoubted relationto crystal structure. J. C . McLennan and W. G. Plummer 67 havemade a preliminary announcement of the determination of thestructure of methane. The cell is cubic, face-centred with fourmolecules, thua resembling the argon structure, as would have beenexpected. The important question of the distribution of hydrogenatoms in the molecule will probably prove too difficult for X-raydetermination.Aliphatic Compounds.-In the past year A. Muller 68 has extendedhis researches into long-chain compounds by an investigation of asingle crystal of the paraffin C,,H6,. This has proved to have anorthorhombic cell, u = 7.45, b = 4.97, c = 77.2 8., containing fourmolecules, space group Vi6.The carbon chains are here perpen-dicular to the (001) cleavage planes, and not inclined to them as inmost other aliphatic types. By careful quantitative studies of theintensities, which were made possible by the use of the Astburyintegrating photometer, the positions of the carbon chains couldbe approximately fixed, and the zigzag arrangement was confirmedin this case also. The following numerical data are the most exactyet obtained in long-chain compounds :Mean distance X between alternate carbon atoms = 2-54 A.Zigzag angle = 84”Cross-section area of CH, chain = 18.5 x 10-l6 sq. cm.Mean G-C distance = 1*9B.Still higher hydrocarbons have been studied by J. Heng~tenberg.6~He obtains the following cells :CsI;R,, ..................7.43 4.97 92.4 2.5a. b. C. Distance, S.C,,H,,, .................. 7.44 4.96 166.4 2.64C!,,,H,,,, .................. 7.44 4-95 - 2.64** W. Heitler and F. London, 2. Physik, 1927, 44, 466; A,, 1927, 923.67 Nature, 1928, 122, 671.68 Pzoc. Roy. Soc., 1928, [ A ] , 120, 437; A., 1176.Z. Krist., 1928, 67, 683294 ANNUAL REPORTS ON THE PROO~~ESS OF OBEMISTSY.in very good agreement with Miiller's values. For the highesthydrocarbon, the orders of the (001) planes cease to be distinguish-able. An investigation by R. Brill and K. Meyer 7O of the acidC,,H.,,*CO,H gives a cell a = 9.76, b = 4-98, c = 36.9 8., p = 48" 6',with four molecules, in accord with t'he structures of other mono-basic fatty acids.Our knowledge of aliphatic compounds is much hindered by thefact that the lower members of most series exist in the liquid statea t the ordinary temperature.Imporfant information has, how-ever, been gained by the study of X-ray scattering in liquids. Ina series of pa'pers, G. W. Stewart, E. W. Skinner, and R. M.Morrow 71 give the results of an examination, by means of anionisstion spectrometer, of the scattering from a, series of primarynormal alcohols, isomeric normal alcohols, monobasic fatty acids,and paraffins with from one to eleven carbon atoms. All exceptthe last show two scattering maxima, corresponding to the mainand side spacings of the solid long-chain compounds. The formerincreases more or less regularly with the carbon content, whilstthe latter remains approximately constant, except in the lowestmembers.The isomeric alcohols gave shorter main and longer sidespacings than their corresponding normal alcohol, as might beexpected. The paraffins gave only side spacings, owing probablyto the lack of a definite group to mark the end of the molecule.It is interesting to note that, in the case of the acids, the longspacings are consistently shorter in the liquid than in the solidphase.These results, as well as those of F. Zernike and J. A. Prins i 2and of C. V. Raman i3 and C. M. S ~ g a n i , ~ ~ all agree with what isknown about the higher members of a.liphatic series, and extendour knowledge by inference to the lowest members. Already thisnew branch of X-ray investigation has shown its usefulness.Whetheror no the diffraction by liquids indicates the existence in the liquidof an incipient crystalline or cybotactic state is more doubtful, asthe maxima may be simply due to a random distribution of mole-cules of definite shape and polarity. Such molecules, if they areto be as close packed as the density of the liquid demands, mustform groups throughout which they lie approximately parallel toG. W. Stewart and R. 11. Morrow, Proc. Nut. Acad. Sci., 1927, 13, 222;A., 1927, 612; Phyeical Rev., 1927, 30, 232; A., 1927, 1016; G. W. Stewartand E. W. Skinner, ibid., 1928, 31, 1, 174; A., 465; R. M. Morrow, ibid.,p. 10; A., 224.'O 2. K k t . , 1928, 67, 570.72 2. Physik., 1927, 41, 184; A., 1927, 206.73 Nature, 1027, 119, 601; A., 1927, 499; ibid., 120, 514; A,, 1027, 1016.74 Indian J .Physice, 1927, 1, 357; A., 1027, 024CRYSTALLOQRAPHP. 296each other like sheep in a narrow pen, but such associations needneither be extensive nor more than instantaneous to produce theobserved X-ray pattern, as Debye has shown.A r m t i c Compounds.-A further important stage in the solutionof the benzene-ring problem is marked by the analysis of the struc-ture of solid benzene by E. G. Cox,75 of which a preliminaryaccounthas appeared. The cell is orthorhombic, a = 7.44, b = 9.65, c =6.81 A. a t 22", and the space group VkK, with four molecules. Thebenzene molecule is shown to possess only a centre of symmetry.Equally important is a preliminary announcement of the structureof hexamethylbenzene by Mrs.Lonsdale.76 This triclinic crystalhas one molecule in the cell, with only a centre of symmetry. Themolecule lies in the ab plane, and has a well-marked pseudo-hexa-gonal symmetry. The molecules are apparently flat, and themolecular sheets are separated by a distance of 3-4 A. The com-pletion of these researches will be very interesting.J. M. Robertson 77 has carried out a very careful photographicinvestigation of two naphthalene derivatives, wix., 1 : 2 : 3 : 4-tetrachloro-1 : 2 : 3 : 4-tetrahydronaphthalene (I) and 1 : 2 : 3 : 4 : 5 : 8-hexachloro-l : 2 : 3 : 4-tetrahydronaphthalene (11). Both structuresWCI C1 HC1are essentially similar to that of naphthalene, the double rings liein the ac planes and a.re probably flat, with the halogen atoms inbetween.Two cyclohexane derivatives, p-benzene hexabromide and hexa-chloride, have been investigated by R.G. Dickinson and C .Bilicke.77" The symmetry is cubic Tz with four molecules in thecell. The molecules have centres of symmetry and trigonal axes.The high symmetry enables the carbon and halogen atoms all to bedetermined by three parameters each. Unfortunately only thehalogen atoms can be definitely fixed; they lie on a puckeredhexagon of 3.4-k side, The carbon atoms probably lie on anotherpuckered hexagonal ring and can be fitted on t o one whose anglesare all nearly tetrahedral. The puckering of the ring and thesymmetry higher than that of the corresponding hexabromobenzene76 Nature, 1928, 122, 401; A., 1081.76 Ib&d., p.810.7 7 Proc. Roy. Soc., 1928, [ A ] , 118, $09; A,, 574; (Sir) W. H. Bragg, X.770 J . Amr. Chern. SOC., 1928, 60, 764; A., 468.RrL9t., 1927, 66, 22; A., 1928, 940296 ANNUAL REPORTS ON THE PROQBESS OF UH3JMISTRY.are probably correlated to the change from benzenoid to paraffinlinkage.Cellulose Derivatives.-X-Ray methods are proving to be of greatuse in investigating the more complicated natural organic com-pounds. Of these, cellulose has been most studied, and its struc-ture has at last been elucidated, a t least qualitatively. In a mostinteresting paper K. H. Meyer and H. Mark T8 review the wholesubject of cellulose and its derivatives.The cell of natural cellulose, as shown by its fibre diagram, hasthe following dimensions :a = 8.7 pi., b = 10.3 A., c = 7-8 8., p = go",the most probable space group Ci containiiig four molecules of" Glucose residue." It is suggested that these molecules arenot separate, as in a molecular crystal, but are joined by aglucoside link through hydroxyl groups in the b direction (which isthe fibre axis) so as to form long-chain molecules held together a tthe sides by ordinary molecular forces.This would make cellulosean example of continuous linkages in one dimension, just as graphiteand diamond linkages extend in two and three dimensions respect-ively. Mercerisation, nitration, and other chemical processes havebeen shown not to affect the structure essentially, but only toalter the cell size and change the relative intensities of reflexionin a reversible way.This is because the substituent groups attackonly the sides of the chain, without breaking the chains themselves.The high molecular weight of cellulose would, according to thisexplanation, refer not to the molecule but to the fibrous crystallites,which retain their structure even in solution. Similar explanationsmay be found to account for the structure and properties of mostother fibrous organic substances, such as silk and chitin, and alsofor such substances as bakelite and other hard organic condensationproducts, where the homopolar links extend in all three dimensions.Crystat Structures : (3) Alloys.Many X-ray investigations on alloys have been reported duringthe past twelve months, and a considerable amount of new lighthas been shed on the chemistry of these substances.From the pointof view of X-ray work, alloys may be divided into three cIasses :(I) Solid solutions which are characterised by random replacementof the parent atoms by the substituent atoms. (2) Inter-metalliccompounds, in which the atoms of different kinds occupy fixedpositions in the structure. (3) Solid solutions which are character-ised by interstitial replacement.Ber., 1928, 61, [B], 693; A,, 621CRY STALLOURAPHY. 297The first category of alloys has recently been the subject of someimportant quantitative investigations. L. Vegard 79 has shownthat certain apparent exceptions to the laws of linear additivitywere due to faulty experimental evidence, and that in both thecopper-nickel and the copper-gold systems the law is approximatelytrue.8* A.E. Van Arkel and J. Basart,81 however, pointed outthat the slight deviations from the law of linear additivity aresystematic, and, with the help of very accurate powder photo-graphs, they show that a more exact relationship can be estab-lished, The law of linear additivity may be expressed in the formLJf = XLB + (1 - X ) L B ,where Lbi, LA, and LB are the lattice constants (the length of edgeof a unit cell) of the alloy M and the pure metals A and B respect-ively, and x and (1 - x) are the concentrations of the two com-ponents. Van Arkel and Basart substitute the more generalrelationshipLJp = XLA" + (1 - x)L&and find that n = 5 for the copper-gold alloys.V.M. Goldschmidt g2 has utilised the above law in order tocompile a comparable set of interatomic distances for the metals.In the elementary state, the metals crystallise in many differentforms. It is, however, quite unsound to compare the interatomicdistances in two metals unless their structures are the same, sincethe value of the interatomic distance is strongly influenced by thedegree of co-ordination (the number of neighbouring atoms). Toavoid this difficulty, Goldschmidt compares only those metalswhich crystallise in the hexagonal close-packed system, or in thecubic close-packed system. In either case, the co-ordinationnumber is 12. When the pure metal does not crystallise in eitherof these ways, Goldschmidt obtains the data from alloys of a metalpossessing the above co-ordination number.Goldschmidt obtains the value of LB from investigations madeon a, metal B with a close-packed structure? and the value of Lbifrom an alloy of A and B with a close-packed structure.LA canthen be calculated from the equation given above. In the absenceof data to the contrary, Goldschmidt puts n = 1. He obtains thefollowing set of values, N being the atomic number and r the radius(in A.u.).L. Vegard and H. Dale, 2. Kriat., 1928,67, 148.80 Compare C. S. Smith, M k . a i d Met., 1928, 9, 468; A., 1313.R1 2;. Krist., 1928, 68, 475.82 is. phyeikal. C'hcm., 1928, 133, 3'57 ; A,, 820.K 298 ANNUAL REPORTS ON THE PROQRESS OF CHEMISTRY.niIn ......Fe ......co ......Ni ......cu ......Zn ......Ga ......Gc ......Atomic radii for a co-ordination number of 12.N . T(12). N . ~ ( 1 2 ) . N .26 1.36 R,u ...... 44 1.322 0 s ...... 7626 1.27 Rh ...... 45 1.342 Ir ...... 7727 1.267 Pd ...... 46 1.370 Pt ...... 7828 1.244 Ag ...... 47 1.442 Au ...... 7929 1.276 Cd, ...... 48 1.621 ...... 8031 - Sn ...... 50 1.582 Pb ...... 8232 1.394 Sb ...... 51 1.614 Bi ...... 8330 1-374 In ...... 49 1.609 gf ...... 81r(12).1.3361.3631.3801.4391-561.7071.7471.82M7heu the co-ordination number is less than 12, the atomic radiusis considerably diminished. The effect may be expressed quantit-atively as follows :L12J --+ [8] 3% contractioii.[121+ [GI 4% 9 ,[121+ C41 12% ))This is comparable with the same effect in ionic compounds.Therelation between co-ordination number and interatomic distance inthe latter bodies may be expressed in the following way :CsCl NaCl[S] -+ [S] 3% contraction.NaCl ZnS (Wurtzite, zinc blende)[6] --+ [4] 50/,-7% contraction.Goldschmidt concludes from this that the binding force in metalsmay after all be very similar to that in ionic compounds. In thisconnexion a paper by J. E. Lennard-Jones and H. J.on the distribution of electrons in a metal, is of considerable interest.Considering a two-dimensional lattice, they obtain the averagedistribution of electrons, using the Fermi-Dirac statistical mechanics.The structure consists of alternate regions of positive and negativeelectricity, so that there is some justification for the electron-latticetheory of metallic stru~ture,8~ but the structure is dynamic, notstatic.W.Hume-Rothery 85 has applied the electron-lattice theory inan attempt to explain some of the properties of metals. The plas-ticity of metals is supposed to be due to the difference in sizebetween the positive ions and the negative electrons which buildup the lattice.The study of alloys by X-ray methods has shown the difficultyof defining the term “inter-metallic compound” in an entirelysa,tisfactory way. A. Westgren and G. Phragmkn have suggested83 PTOC. Roy. Soc., 1928, [ A ] , 120, 727; A,, 1299.85 Ibid., 1927, 4, 1017; A,, 1928, 111.Lindemann, Phil. Mag., 1915, 29, 127; A., 1915, ii, 47.Ibid., 1936, 60, 311; A., 1926, ii, 746that “ in an ideal inter-metallic compound structurally equivalentatoms are chemically identical.” W.Hume-Rothery,*’ however,considers that only those substances which may be supposed toshow either electron-sharing or electron-transference should beregarded as chemical compounds. Whichever definition be accepted,there remains the difficulty that, for the most part, no clear dis-t,inction can be made between solid solutions and inter-metalliccompounds, since most alloys are intermediate in character, andoften confiicting results are obtained in the study of thesesubstances. The copper-tin system is an interesting case inpoint.The copper-tin alloys have recently been investigated by A.Westgren and G. Phragmh 88 and by J.D. BernaLa9 The a-phaseconsists of a solid solution with the copper type of structure (face-centred cubic), and the p-phase appears to be a solid solution of thebody-centred cubic type; but the 6-, E-, and ?-phases show someextraordinary features. According to Westgren, the c-phase is asolid solution with a hexagonal close-packed structure. Bernal *has shown that it is much more complex, and that a possible formulawould be Cu,,,Snl6, the space group probably being Vi7. Thestructure is in fact almost hexagonal close-packed, but the copperand tin atoms are too dissimilar to be arranged at random. Thedeparture from hexagonal symmetry is very difficult to detect, andW. M. Jones and E. J. Evans have also reported this structureto be hexagonal close-packed.According to Westgren and Phrag-m6n, the q phase has a nickel arsenide structure, so that its formulashould be CuSn, but Bernal finds that Cu6Sn5 is nearer the truth,and considers that the unit cell probably contains 230-250 atomsof tin and 280-300 atoms of copper.The %phase of the copper-tin system is also extraordinarilycomplex, the unit cell, which is face-centred cubic, containing 416atoms. The range of homogeneity of this phase is extremely narrow,and chemical analysis shows that the formula is about Cu,,Sn8,though symmetry considerations show that it is not possible todivide the 416 atoms in exactly this ratio. The formula Cu,,Sn,receives support from the remarkable fact that it has the sameconcentration of valency electrons as occurs in the alloys Cu,Zn8 91* It should be noted that Bernal’s e is Westgren’s 11, and ?*ice zw8a.8 7 Lindemann, Phil.Mag., 1928, 5, 173; A., 222.8s 2. anorg. Chem., 1928,175, 80; A., 1174.89 Nature, 1928, 122, 64; A., 822.90 Phil. Mug., 1927, (vii), 4, 1302; A,, 1928, 6.91 A. J. Bradley and J. Thewlis, PTOC. Roy. Soc., 1926, [ A ] , 112, 678; A,,1926, 1084300 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.and CusAIp,g2 which agrees with Hume-Rothery's hypothesis 93 thatthe ratio of valency electrons to atoms should be the same inanalogous phases of the three systems Cu-Zn, Cu-Al, and Cu-Sn.A. J. Bradley and C. H. Gregory,94 in an investigation of ternaryalloys of copper, zinc, and aluminium, show that this type of struc-ture is still preserved in the ternary alloys, so long as the ratio ofvalency electrons to atoms is maintained.Westgren and Phragmdn 95 have made a detailed attempt to tracethe applicability of the Hume-Rothery relationship to a largenumber of alloy systems.They conclude that the p-phase (body-centred cubic) occurs in the systems Ag-Mg, Ag-Zn, Ag-Cd,Au-Zn, Au-Cd, Cu-Al, Cu-Sn, and Cu-Zn, usually when the ratioof valency electrons to atoms is approximately 312. Phases witha atructure like that of y-brass (Cu,Zn,) occur in the systemsAg-Zn, Au-Zn, Ag-Cd, Ag-Hg, Cu-Cd, Cu-Al, and Cu-Sn usuallywhen the ratio of valency electrons to atoms is about 21 to 13.Hexagonal close-packed structures appear in the systems Cu-Zn,Ag-Zn, Au-Zn, Ag-Cd, Au-Cd, Ag-Al, Au-Al, Ag-In, Cu-Sn, Ag-Sn,Cu-Sb, and Ag-Sb usually when the ratio of valency electrons toatoms is about 7/4.There are many exceptions t o the valency rule,but it is the first successful attempt to systematise alloy structures,and is therefore of great importance.The silver-cadmium system 969 97 fits in very well with the Hume-Rothery rule, each of the phases of the copper-zinc system appearingin the correct order ; there is, however, a high-temperature modific-ation of the p-phase, stable above 400" and possessing a hexagonalclose-packed structure. The silver-aluminium system 98 is onlypartially analogous to the copper-zinc system. Instead of a body-centred cubic structure, at a concentration of 312 valency electronsper atom one obtains a complex structure, isomorphous with P-man-ganese, the structure of which has been determined by G.D.Preston.99 He finds that the unit cell is cubic, the length of theside being 6-29 8., and contains 20 atoms, in agreement with theresults of Westgren and Phragm6n.l The space group is 0 8 or 0 7(enantiomorphous forms), and the structure consists of two groupsof structurally equivalent atoms, containing respectively 12 and91 A. J. Bradley, Phil. Mag., 1928, 6, 878.913 W. Hume-Rothery, J. Inst. Metab, 1926, 35, 313.94 Mem. Mancheater PhiZ. Soc., 1927-1928, 72, 91.95 MetaZZ&rtschaft, June, 1928.96 G. Natta and M. Freri, Atti R. Accad. Lincei, 1927, 6, 422, 505; 1928,97 H. Amtrand and A. Westgren, 2. anwg. Chem., 1928,175, 90; A,, 1176.98 A.F. Westgren and A. J. Bradley, Phil. Mag., 1928, 6, 280; A.. 1078.95 Ibid., 5, 1207; A., 820.7, 406; A., 1928, 223, 464, 820.8. Ph,yaik, 1926, 33, 777CRYSTBUOaRAPHY. 3018 atoms. The composition of the isomorphous alloy is, however,Ag,Al, so that it is impossible to divide the silver and aluminiumatoms into groups of 12 and 8. Most probably they are distributedat random.Copper-magnesium alloys 2 are entirely different from copper-zinc alloys. There are two phases, CuMg and CuMg,. J. B.Friauf has completely determined the structure of CuMg,. Theelementary cell contains 24 atoms, the arrangement of the atomsbeing the same as that of the metal atoms in pin el.^ The phaaeCu-Mg is face-centred rhombohedral, with 48 atoms in the unit cell.All the alloys so far described contain a metal of the copper-silver-gold group.It is interesting to note, however, that phases analogoust o those of the copper-zinc system occur in the iron-zinc system,but there is no approximation to the Hume-Rothery relationship.Alloys of iron in general show no resemblance to the alloys of thecopper group of metals. A striking feature is their tendency tointerstitial replacement, small atoms such as nitrogen or carbonreadily finding a place in the interstices of the metal lattice. Theformation of this type of alloy is an important factor in the harden-ing of steel. According to W. L. Fink and E. D. Campbell,s wheneutectoid and hypoeutectoid steels are drastically quenched, atetragonal structure is formed, intermediate between a body-centredand a face-centred cubic structure. At high temperatures, thecarbon atoms occupy positions between the iron atoms, which arethemselves on a face-centred cubic lattice. Apparently, on rapidquenching, the carbon atoms have not time to escape from theirpositions, and this inhibits the change to the body-centred structure,a metastable structure being formed with the carbon atoms stillbetween the iron atoms.'in whichthe nitrogen atoms force their way in between the iron atoms. Thefirst effect of this is to transform the iron lattice to the high-temperature structure (y-iron, face-centred cubic), the nitrogenatoms again occupying the interstices of the structure. A closeexamination of the structure 93 10 shows that the nitrogen atomsThe action of ammonia on iron gives rise to nitridesA. Runqvist, H. Arnfelt, and A. Westgren, 2. anorg. Chem., 1928, 176,J . Amer. Chem. SOC., 1927, 49, 3107; A,, 1928, 109.(Sir) W. H. Bragg, Phil. Mag., 1916, 30, 305.A. Osawa and Y. Ogawa, 2. K d t . , 1928, 68, 177.Trans. A.S.S.T., 1926, 9, 716; B., 1926, 919.N. Seljakov, J. Kurdjumov, and N. Goodtzov, Nature, 1927,119,494 ;U. Hiigg, Nature, 1928, 121, 826; A., 605.IJ R. Brill, Nnturwisa, 1928, 16, 693; A., 940.lo G. Hhgg, Nature, 1928, 122, 314; A., 1081.43; A., 1175.2. Phyeik, 1927, 45, 384; A., 1927, 400, 1128302 ANNUAL REPORTS ON I'HE PROGRHlSS OW CHEMISTRY.occupy definite positions, so that the structure probably correspondsto the formula FeJY.Another type of alloy with interstitial substitution is obtainedwhen hydrogen is dissolved in metals. The well-known case of thepalladium-hydrogen " alloys " has been the subject of a largenumber of investigations by X-rays. According to J. 0. Lindeand G. Borelius,11 when palladium is heated in an atmosphere ofhydrogen, the gas is absorbed in the interstices of the lattice.Up to a certain concentration of hydrogen, depending on thetemperature, the palladium lattice (face-centred cubic) is present,but the lattice steadily expands. With greater concentrationsof hydrogen, a sudden increase in lattice constant occurs,apparently corresponding to the formation of the compoundPd,H. When palladium is made the cathode during the electro-lysis of dilute sulphuric acid, it absorbs hydrogen and forms acompound PdH with a still greater lattice constant. Splutteredfilms of palladium, prepared in the glow discharge of hydrogen, arefound to have the structure of the metal with an increased latticecomtant,12 and the same is true of platinum. Nickel, however,forms a hydride of the hexagonal close-packed type. In thisrespect it is analogous to copper,13 which forms a hyciride, CuH,with a hexagonal close-packed structure.W. LAWRENCE BBRAGG.R. W. JAMES.J. D. BERNAL.A. J. BRADLEY.l1 Ann. Physik, 1927, [iv], 84, 747; A., 1928, 109.l2 G. Bredig and R. Allolio, 2. physiknl. Chem., 1927, 126, 41 ; A., 1927,l 3 H. Muller and A. J. Bradley, J., 1926, 1669; A,, 1926, 889.502

ISSN:0365-6217    

DOI:10.1039/AR9282500275

出版商:RSC    

年代:1928

数据来源: RSC

摘要:

SUB-ATOMIC PHENOMENA AND RADIOACTIVITY.THE work of the two years (1927-28) under review has been rendereddistinctive by the experiments of F. W. Aston on the exact massesof isotopes with a new mass-spectrograph, and by the theoreticalwork of Sir E. Rutherford on the structure of t*he nucleus of thoradioactive atom, particularly with reference to the origin of thea-particle. These investigations promise to enable advances to bemade on a wider front than has for some time been possible. Onthe chemical side, important work has been done on the elementsprotoactinium and potassium. The activity in attempts to trans-mute the heavier elements by simple laboratory apparatus, whichat the time of the last Report (1926) was a t its height, has nowsubsided ; the hostile critics have won, although all the remarkableresults obtained during the active period have not yet been with-drawn.No attempt is made in the following pages to summariseall the important work done during the period. Certain topics ofinterest to chemists have been selected for description and commentin a fuller manner than heretofore, whilst much excellent work ofn more physical nature, such as that on details concerning the a-,p-, and y-rays, has been omitted.Mass-spectra, Isotopes, and the Packing Effect.A great advance has been made in knowledge of the isotopicconstitution of elements, the masses of the individual atoms on thescale 0 = 16, and of the (‘packing fraction” by F. W. Aston 1with his new mass-spectrograph. (The packing fraction is thedivergence of the atom from the whole-number rule divided by itsatomic mass, and its importance lies in its being a measure of thegain or loss of mass per proton when the nuclear packing is changedfrom that of oxygen to that of the atom under examination.) Thehew mass-spectrograph has five times the resolving power of theold one-far more than Sufficient to separate the mass lines of theheaviest elements.The photographed spectrum is nearly 16 cm.long and includes more than one octave of mass, the dispersionscale for a change of mass of 1% varying from 1.5 mm. at the mostdeflected end to 3.0 mm. at the least deflected end. The accuracyattained is 1 part in 10,000 parts, which is sufficient to give first-order values of the divergence of the masses from whole numbers.Three methods of measuring the mass ratios are described, includingProc.Roy.Soc., 1927, [A), 116,487; A,, 1827,914; N&u% 1027,120,966304 mu.& R ~ O B T S ON TBP PROGRESS ow UHIPM~STRY.the method of coincidences, which consists in photographing invirtual coincidence the lines due to an unknown maas and a knownmass, by applying suitable potentials the ratio of which differs byabout 0.5% from the expected ratio. The intervals between thelines obtained in this way are measured with a tilting-plate micro-meter and converted into intervals of mass by multiplying by thedispersion constants calculated for the mid-point of each interval.The unit of mass is the neutral oxygen atom 0l6, and the massesmeasured are corrected for the mass of the electron.They maytherefore be compared directly with those of the atomic-weightstable. In Table I are given the results of the measurements, withthe addition of those for lithium calculated from J. L. Costa'sresults.2 It may be noted that the old distinction between theelements which obeyed the whole-number rule and those, like tin,whose masses were found to be less than an integer by 0.1 or 0.2unit, has disappeared under more accurate work.Atom.HHeLi6LiB10331'CN0FNe20Ne231'A36c135TABLE I.Packing fraction Massx lo4. (0 = 16). Atom.77.8 & 1.5 1.00778 C1375 4 & 1 4.00216 A4020.0 & 3 6.012 As17.0 4 3 7.012 Kr7s13-5 & 1.5 10.0135 Br7910.0 & 1.5 11*0110 K r 8 03.0 & 1 12.0036 Br815.7 2 14.008 Kr820.0 16.0000 Kre30.0 f 1 19.0000 Kr8*0.2 1 20.0004 Krso-5.6 & 1.5 30.9825 Sn120-4.8 -!- 1.5 34.983 Xe134-6.6 1.5 35.976 Hg200Phzoe(ca.) 2.2 22.0048 IPecking fractionx 104.-5.0 & 1.5-7.2 & 1-8.8 & 1.5-9.4 & 2-9.0 & 1.5-9.1 5 2-8.6 & 1.5-8.8 & 1.5-8.7 & 1.5-8.5 & 1.5-8.2 -1- 1.5-5.3 & 2-77.3 5, 2-5.3 & 2$0.8 & 2$0.8 i 2--Mass(0 = 16).36.98039.97174.93477.92678.92979.92680.92681.92782.92783.92885.929126.932119.912133.929200.0 16206.0 16The packing fraction gives entirely new information about fhenucleus, for it is a measure of the forces binding the protons andelectrons together.High packing fractions indicate looseness ofpacking and therefore low stability; low packing fractions, thereverse. If packing fractions are plot'ted against the atomic massesit will be seen that, starting a t hydrogen with a large posit'ivepacking fraction, the curve drops rapidly, crosses the zero line nearmass 20 and sinks to a minimum value of - 10 x 104 at aboutNP8 (as shown by later, provisional experiments), rises again, andrecrosses the zero line in the region of mass 200. For light massesof elements of even atomic number the initial drop of the curve isAnn. Phyaique, 1925, [XI, 4, 425; A . , 1925, ii, 1021SUB-ATOMIC PHENOMENA AND RADIOACTIVITY. 306much less marked than for the masses of odd atomic number, thetwo initial parts of the curve joining at about a mass of 40 or 50.It is thus apparent that the fundamental difference between elementsof odd and those of even atomic number, already shown in isotopicconstitution, in their relative abundance in nature, and in thebehaviour of their nuclei under the disintegrating impact ofa-particles, applies also to the looseness of the packing of the twosets of nuclei.There is apparently no periodicity in the values ofthe packing fraction, and the results obtained are considered to bein harmony with Sir E. Rutherford’s3 view of the structure of thenucleus, namely, that it consists of an inner, uniform, tightlybound structure, outside which is a looser system of neutrons,protons, and electrons, which is the more complex the heavier theelement.The accuracy of the measurements and the consistency of theresults among themselves leave no doubt that for simple elementsthe results obtained are the true atomic weights.(When notdetermined directly they may be obtained accurately from the plotof packing fraction against atomic mass.) In most cases theagreement between these results and those obtained by the ordinarymethods of atomic-weight determination is good. The acceptedatomic weights of all the simple elements mentioned in Table I arevery close to the values of the atomic-weights table; that forphosphorus, 31.04, is probably a little too high.In the light of these results, it is interesting to consider thethree changes in the accepted values of atomic weights recentlyadopted by the German Commission.* The new value for argon,39.94, is in excellent agreement with the estimated ratio of A36 toA4O, vix., 1 : 100, and the exact masses of each. The new value fortitanium, 47.90, is 0.07 too low, if titanium should be found to besimple; that for yttrium, 89.93, is exactly right.On the otherhand, the atomic weight of czesium deduced from F. W. Aston’sresults is 132.93, whereas a redetermination by T. W. Richardsand M. Frangon6 confirms the accepted value, vix., 13241. Inthis case, as the authors point out, the discrepancy may be due tothe existence of a second, lighter, isotope in czesium of mass (it ispresumed) 131. This, however, has not been observed by F. W.Aston,6 and the possibility of the lighter isotope of an element ofodd atomic number being less prevalent in nature than the heavieris unusual.The value for the (common) lead isotope 206, vix.,206.016, is in excellent agreement with the latest determinationInfra, p. 309.J . Amer. Chein. Soc., 1928, 50, 2162; A,, 1069.4 B e y . , 1928, 61, [ R ] , 1 ; A., 1828, 214.6 Ann. Report, 1922, 19, 270306 ANNUAL REPORTS ON THE PROGRESS OF OHI$MISTRY.by T. W. Richards and L. P. Hall for uranium-f2 corrected for thepresence of thorium-R, 206.02, although here a difficulty may beconcealed since uranium-i2 presumably contains 3 yo of the actiniumend-product of atomic weight 207 or 209. The fact that the packingfraction for masses above 200 is positive and increasing is consistentwith the fact that the values of the atomic weights of thorium anduranium (which, in the chemical sense, are almost certainly simple)are in excess of whole numbers, but not with the value for radiumwhich is accepted as 226.0.This value, a,s pointed out some yearsago,* appears to be at least 0.1 unit too low.During the period under review knowledge of the isotopic con-stitution of seven elements has been extended. The results aregiven in Table IT.TABLE 11.Element.Neon ...............Zinc ...............Germanium ......Tin ..................Xenon ............Mercury ............Lead ...............Atomicnumber.103 0325064SO82Minimumnumber ofisotopes.378119F4Masses of isotopes in orderof intensitie~.~20, 22, 2164, 66, 68, 67, 65, 70, 6974, 72, 70, 73, 75, 76, 71, 77120, 118, 110, 124, 119, 117, 122,129, 132, 131, 134, 136, 128, 130,202, 200, 199, 198, 201, 204, 196,208, 206, 207, 200121, 112, 114, 115126, 124The results for neon, obtained by T.R. Hogness and H. M.Kvalnes lo with a mass-spectrograph of the Dempster type, confirmthe original (but subsequently doubted) result of F. W. Aston11that a small proportion of the isotope 21 exists; this proportion isnow found to be about 2% of the whole. The results for zinc wereobtained by F. W. Aston l2 with the new mass-spectrograph,l usinga specimen of zinc methyl; they supplement the earlier results ofA. J. Demp~ter.1~ The remainder of the results given above wereobtained with the same instrument.Those for tin, xenon, andmercury are extensions of results previously published, and referto isotopes present in relatively very small concentrations ; thenew isotope, 196, of mercury, for example, constitutes only 0.04%of the whole. The results for lead,1* obtained with a specimen? J . Amer. Clmn. SOC., 1926, 48, 704; A., 1926, 449.* A. S. Russell, Nature, 1924, 114, 717; A,, 1924, ii, 813.The order of the isotopes of sulphur is given correctly in .4nn. Repor!,1926, 23, 281, but not subsequently.'lo Noture, 1928, 122, 441; A., 1169.I1 Phil. Mag., 1920, [vi], 39, 454; A., 1920, ii, 277.l2 Nature, 1928, 122, 345; A., 1069.l3 Phy8icalRev., 1922, [ii], 20, 031; A., 1923, ii, 413.14 Nature, 1927, 120, 224; A., 1927, 806SUB-ATONIC PHXNOMEXA ANT) RADIOAUTIVI'rY.307of lead tetramethyl, are new. Indications were also give11 in leadof small proportions (not necessarily smaller than that of isotope209) of masses 203, 204, and 2015, but these could not be ascribedwith certainty to lead owing to the presence of mercury. From ageneral survey of F. W. Aston's results certain other points standout clearly. First, isobares, hitherto confined to masses of evennumber, are now extended to those of odd number; for instance,the mass 75 is common to germanium and to arsenic, 69 to zinc andgallium. Secondly, there appears to be no simple rule to describeeither the number or the order of intensities of the isotopes ofelements of even atomic number; further investigation tends toreveal isotopes undetected in the initial investigation.Thirdly,elements of odd atomic number seem much less complex; theirisotopes seem limited to two, the masses of which (beyond nitrogen)are of odd number and differ by two, and their proportion in natureis often approximately a simple one such as 1 : 0, 1 : 1, 3 : 1, thelighter being not the less prevalent; in consequence, if the atomicweight of an element of odd atomic number be definitely in excessof an integer, the element is probably a mixture of two isotopes.Separation of Isotopes, and the Radioactivity of Potassium.During the period under review, negative results have beenobtained in several investigations15 carried out with a view toshow that different isotopic concentrations of an element may beobtained from different sources of material.H. V. A. Briscoe,P. L. Robinson, and H. C. Srnith,lG however, continuing their workon boron, find a real difference of approximately 0.01 in the meanatomic weights of boron from California and from Asia Minor.Several attempts 1' to concentrate one isotope in a mixture havealso failed. E. R. Jette 18 discusses the available theoretical andexperimental work on the possibility of separating isotopes bymethods which depend on the assumed influence of the differentmasses of the isotopic ions on their mobilities in solution, andconcludes that none of them can lead to a positive result.Notable successes have been obtained by W. D. Harkins andB. Mortimer l9 with mercury, and by W.D. Harkins and C. E.Broeker 2o with chlorine. With mercury, their former apparatushas been modified to allow of more rapid working, and mercuryIs (Mlles.) E. Gleditsch and L. Gleditsch, J. Chim. physique, 1927, 24, 238;A., 1927, 493; K. R. Krishnaswami, J . , 1927, 2534; A., 1927, 1120.l6 J . , 1927, 282; A., 1927, 392.l7 H. S. King, J. Amer. Chem. SOC., 1927, 49, 1500; A., 1927, 709.la Phil. Mag., 1927, [vii], 3, 258; A., 1927, 182.le Ibid., 1928, [vii], 6, 601; A., 1301.2* Z. Phpik, 1928, 60, 637; A., 1301308 ANNUAL REPORTS ON THE PROGRESS OF HEMI IS TRY.with an atomic weight differing by 0.189 unit from that of ordinarymercury has been obtained by fractionation. This is a recorddifference. With chlorine, a diffusion method with hydrogenchloride left 1/8000th of the original gas, which on analysis had anatomic weight approximately 0.055 unit higher than that of chlorine.The work of G.von Hevesy and co-workers 21 on the concentrationof the isotope of mass 41 of potassium is of double importancebecause it throws light on the feeble radioactivity of this elementand by inference on that of rubidium. In order to discover whichof the isotopes is responsible for the emission of the p-particles,they submitted one litre of liquid potassium to ideal distillation,the metal being maintained at 160°, and the potassium surface, onwhich condensation took place, being cooled by solid carbon dioxide ;the distance between hot and cold surfaces was maintained at lessthan 1 cm.The final residual fraction was found to have anatomic weight of 39.109, which is 0.005 unit greater than that ofordinary potassium. It contains therefore, it was calculated atthe time, 443% more of the isotope of mass 41 than does ordinarypotassium. (Recalculated on F. W. Aston’s exact values 22 for theisotopes of potassium, this value becomes 4.0%). The activitiesof equal masses of the chlorides of the heavy residual fraction andof ordinary potassium were compared by means of Hoffman’svacuum electrometer and the difference was found to be 4.2 3 0.7%.This result agrees so well with that to be expected from the observedchange in atomic weight that it is concluded that the isotope 41 issolely or mainly responsible for the p-particles emitted.Interestingdeductions are made from this remarkable result. First, if it beassumed that rubidium owes its activity to its higher isotope, itsgreater activity than that of potassium is simply explained-forthere is more of it. CEsium, on the other hand, having apparentlyone isotope only, may be said to have no heavier isotope and thereforeno radioactivity. (There are objections, however, to this view. Itassumes a connexion between the alkali elements and radioactivitywhich is a priori unlikely. Again, it is not impossible, as has beenmentioned above, that casium has a lighter isotope; if so, theabundant heavier isotope, which actually is inactive, should beactive.) Secondly, the value for the half-period of potassium,given by A.Holmes and R. W. L a ~ s o n , ~ ~ now requires correc-tion to the value they gave on the assumption that the activity of21 Nature, 1927, 120, 838; A,, 1928, 4; M. Biltz and H. Zeigert, Physikd.Z., 1928,29, 197; A., 454; G. yon Hevesy and M. Lagstrup, 2. canorg. Chem.,1928,171, 1; A., 684.22 Sztpra, p. 304.2L,a Nature, 1926, ll?, 630; A., 1926, 554; Phil. Mag., 1926, [vii], 2, 1218;A., 1027, 80SUB-ATOMIC PHENOMENA AWD RADIOACTIVITY. 30 9potassium is due to the mass 41, viz., 7.5 x 1010 years, a result ofthe order of the half-period of thorium. From this period it maybe calculated that 2% of this isotope has disintegrated since theconsolidation of the earth's crust, and that a t one time the atomicweight of terrestrial potassium was as much as 0.002 unit greaterthan now.If the emission of the @-particle effects an alteration inthe nuclear charge, the product of transformation of potassium willbe the calcium isotope 41, a product hitherto not detected in nature,but one which should show itself in an atomic-weight determinationof calcium extracted from old potassium minerals. Potassium,which expels @- but no a-particles and has an enormous half-period for the isotope which expels p-particles, presents an interest -ing contrast to a (heavy) radioactive element where the emissionof a- is always more obvious than that of @-particles, and where thenuclear P-particle, when detectable, is never associated with aproduct of half-period greater than 20 years.Structure of the Radioactive Nucleus and Origin of the a-Particles.Sir E.Rutherford 24 has put forward a singularly complete theoryof the structure of the nuclei of radioactive atoms, based on, anddiscussed in terms of, the experimental data. The two sets ofobservations on which the theory is largely based are : (1) Thefact that in radioactive transformations an a-particle from a givenatom is expelled with a remarkably constant speed ; this is regardedas a strong indication that the a-particle in the nucleus is circulatingin a quantised orbit and released therefrom a t a definite character-istic velocity. (2) Although experiments on the scattering ofa-particles appear to indicate that the nucleus of a heavy atomsuch as uranium must have a radius smaller than 3.2 x 10-l2 cm.,computation from radioactive data makes the nuclear radius atleast twice as great as this.This divergence is most easily explainedby the assumption that if any constituent particles of the nucleusextend to a distance of 6 x cm. they must be electricallyneutral. These neutral particles circulating round the inner nucleusare regarded as being held in equilibrium, either by magneticforces arising from the inner nucleus, or by attractive forces due tothe distortion or polarisation of the particle itself by the electricfield. In the theory the latter forces are considered operative, sincelittle is known of the former. First is considered theoretically themotion of a neutral satellite moving in a circular n-quantum orbitaround the central nucleus under the attractive forces due topolarisation of their structure by the field from the nuclear charge;a4 Phil.Mag., 1927, [vii], 4, 680; A., 1927, 1002310 ANNUAL RErorcrs ON THE PROCZRRSR OF UFIEMTSTRY.then the theory is modified to account for the fact t’hat the neutralsatellite escapes as a doubly-charged particle. It is supposed thatthe satellite loses its two electrons and becomes the a-particle whenfhe energy stored in it due to distortion falls below a certain criticalvalue, the same for all a-particles. Various relations are derived,principally one connecting the energy of emission of an a-particlewith the fourth power of the quantum number n and three con-stants. The values of these constants are obtained from the dataof the uranium-radium series, and when quantum numbers (insome cases half quantum numbers) are assigned to each productof the three series expelling a-particles, the energies of emission ofa-particles calculated from this relation are found in all cases to bein agreement (within the error of experiment) with those determinedexperimentally ; the agreement is particularly striking for themembers of the thorium series.Certain quantum orbits are foundto be common to two elements; the number 24, for example, isassigned both to radium-A and to thorium-C, the number 23.5to both thorium-X and actinium-X. On this theory, the existenceof the long-range a-particles expelled by radium$’, thorium-G’,and actinium-C receives a ready explanation, vix., that while themajority of the atoms break up in one way due to the liberation ofthe satellite from a definite quantum orbit, a small proportion ofthe atoms may liberate satellites from other and presumably deep-seated orbits.Thus the long-range particles from both radium0and thorium-C’ correspond with the quantum number 31, whereasthe ordinary a-particle from the former product corresponds withthe number 28 and that from the latter with the number 30.In the calculations which lead to this successful issue, the radiusof the satellite (which later becomes the a-particle) is found to beabout 6 x lO-I3 em., and hence the volume is approximately1 x 10-36 C.C. This is in good agreement with the volume (0.5 x10-36 c.c.) calculated from the experimental results of J.Chadwickand E. S. Bieler 25 for the region surrounding the particle wherethe forces are known to be abnormal. Reasons are next given foranticipating that the radioactive constant X should be connected,not with the final energy of escape of the or-particle, as it is inGeiger and Nuttall’s relation, but with the quantum numbercharacterising the orbit which is liberated, and with a quantitydepending on the constitution of the central nucleus. The relationfound, although satisfactory, is not as simple as was anticipated.The theory extends also to the y-ray which is known, from thework of C. D. Ellis, (Frl.) L. Meitner, and others, to have its originin the nucleus. The y-ray is considered to arise when a satellite25 Phil. &Zag., 1021, [vi], 42, 823; A., 1922, ii, 12SOB -ATOMIC] PHENOMENA AND RADIOACTIVITY.311moves from one quantum level to another, a view in harmonyvith results for radium, actinium-X, radioactinium, etc., wherethe y-ray either accompanies or follows transformations in whichonly a-particles are emitted. Coincidences are found (within experi-mental error) between the observed energy of the y-rays and energycliff ereaces between various levels, The agreements are regarded,however, with some diffidence, owing to the large number of energylevels possible, and further discussion is reserved for a latereommunication.On this theory the iiucleus has three well-defined regions in itsstructure. The inmost part is very compact with a volume ofradius not greater than 1 x 10-l2 cm., a closely ordered, " crystal-line" arrangement of its component electrons and protons. Thiscentral nucleus probably does not vary regularly in charge and massfrom atom to atom but is common to several elements; it is quitelikely that it is common to all the elements of a radioactive series.Round this central part is a region extending to a radius of about1.5 x 10-l2 cni., occupied by electrons and possibly also chargednuclei of small mass; the electrons here circulate with velocitiesclose to that of light.Outside is the comparatively large volumebetween radii of 1.5 x 10-12 and 6 x 10-l2 cm., probably occupiedby a number of neutral satellites held in equilibrium by the polarisingaction of the electric field arising from the central nucleus.Nodefinite information is yet available as to tho number of these, orwhether they are all of the same kind ; radioactive evidence suggeststhat helium satellites are there, and a study of the relative massesof isotopes by F. W. Aston suggests that masses of 3,2, and possibly1 are also present. From the theory it is calculated that heliumsatellites are possible in the nucleus of an atom of as low an atomicnumber as 15, and should become numerous for an atomic numberof 30-a result which is in agreement with the fact that the averagenumber of isotopes per element increases in a marked mannerabove element 29. In a radioactive atom one of the neutral heliumsatellites, circulating in a quantised orbit round the central nucleus,for some reason becomes unstable and escapes, losing its two elec-trons when the electric field falls below a certain critical value;it leaves the atom with a speed depending on its quantum orbitand nuclear charge.The electrons liberated from the satellite falltowards the central part of the nucleus and circulate with nearlythe speed of light in the region between this nucleus and where thesatellite had been; if one is hurled out of this system it becomes adisintegration electron. The disturbance to the neutral satellitesystem by one of the causes mentioned may lead to its rearrange-ment, involving the transition of one or more satellites from on312 ANNUAL REPOBTS OR THE PROGRBSS OF OHMMISTRY.quantum orbit to another, and this leads to the emission of a pray,the frequency of which is determined by quantum relatiom.In this work it was found by the scintillation method that H.GFeiger’sg6 value for the range of the a-particle from uranium-I1is too low, by a t least 0.16 cm.This has been confirmed by GF. C.Laurence,Z7 who measured tthe range in a Wilson expansion chamberand found 3.28 cm. & 1%. This alteration in range involves acorresponding change in the estimated value of the product’shalf -period .28Artificial Transmutut ion.The opposition to the claims of transmutation by the use ofprocesses other than swift a-particles, which had begun to set in atthe date of the last Report,29 has now become so strong as to leavelittle doubt that the claims are quite untrustworthy.F. Bernhardt 30describes a mercury arc in which quantities of gold of the orders10-7 and g. have been obtained from mercury originally shownto be free from it, and at one time A. Smits and A. Karssen31thought they had obtained as much as 0.1-0-2 mg. of mercury(as iodide) from lead. Other workers, however, announce eithercompletely blank experiments 32 or doubts or withdrawals 33 oftheir former conclusions. It may therefore be concluded withsome certainty that the introduction of an electron into the nucleusby electrical means with consequent formation of one elementfrom another has not been accomplished. B. Walter 34 subjecteduranium-X, to the action of hard X-rays in the hope that theywould eject an electron from the K-ring and that this would bereplaced by an electron from the nucleus, and so increase the rateof expulsion of p-particles ; the results, however, were negative.H. Herszfinkel and L.Wertenstein 35 attempted to accelerate therate of radioactive transformation of thorium by bombardingthorium oxide with or-particles from radon but observed no change.The experiments of F. Paneth and K. Peters,36 which led to theas Z . PJiyaik, 1921, 8, 45.2 1 PTOC. Nova Scotian Imt. Sci., 1927, 17, 103; A., 1928, 4; Phil. Nag.,1928, [vii], 5, 1027; A,, 684.28 Infra, p. 319.29 Ann. Report, 1926, 23, 286. 30 Physikal. Z., 1926, 27, 713; A., 1927, 5.31 2. Elektrochem., 1926, 32, 677; A., 1927, 87.32 H. H. Sheldon and R. S. Estey, Phyaicd Rev., 1926, [ii], 27, 515; A.,33 A.Smits, a i d . , 1927, 120, 475; A., 1927, 1004; A. Smits and W. A.1927, 1004; L. Thomassen, Nature, 1927,119, 813; A,, 1927, 606.Frederikse, 2. Elektrochem., 1928, 34, 360; A., 933.36 8. PhY8iky 1926, 39, 337; A., 1926, 1190.35 Nature, 1928, 122, 504; A,, 1169.36 BEI., 1926, 59, [BJ, 3039; A,, 1026, 1077SW-ATOMIC PHENOMEXA AND RADIOASBTIVITY. 313remarkable conclusion that a minute volume of helium may besynthesised from hydrogen by dissolving the latter in palladium,have now been explained by the authors themselves and P.Gunther 37 in a more prosaic but still interesting manner. Heliumis not synthesised in detectable amount under the conditions oftheir experiments: its source is not in the palladium but in theglass. It was found that a glass tube which has been completelyfreed from its content of helium by heating it in hydrogen takesup a detectable amount of neon-free helium from the atmosphereeven after only one day's contact with it.Also, glass tubes whichfail to give off detectable quantities of helium when they are heatedin a vacuum or in oxygen give off volumes of the order of lev C.C.after they have been heated in hydrogen. It is concluded thatwhen an apparatus of glass is used, a trustworthy statement as tothe origin of C.C. of helium cannot be made if air comes incontact with the apparatus, parts of which are later heated in anatmosphere of hydrogen. It may be hoped that the frank with-drawal of an experimental result, which mas completely at variancewith much of the best-established work on nuclear physics, willencourage those who have arrived at similar sensational results todo likewise.It is abundantly clear, from the experiments whichhave been described, that in work of this kind, i.e., the formationof one gaseous element from another, the blank experiments havenot been sufficiently rigorously carried out. In later experimentsthe authors38 have so improved their methods that C.C. ofhelium (or neon) can be detected with certainty. With this appar-atus they have tested the possibility of the artificial formation ofhelium from other elements under various conditions, such asbombardment of potassium compounds by cathode rays, passageof an electric discharge, with or without electrodes, through hydrogenor compounds of hydrogen, and the action of p-particles and y-rayson water and mercury. When precautions were taken to excludethe possibility of the entry of air, or the diffusion of helium fromthe air through hot glass, or the escape of helium occluded in glass,the results were entirely negative; no quantity of helium largerthan 10-lo C.C.was obtained.Preparation and Properties of Protoaclinium.A. von Grosse39 has for the first time prepared protoactinium(as oxide) in weighable amount by working up large quantities ofJoachimstal pitchblende residues. Fusion of the material withBer., 1927,60, [ B ] , 808; A., 1927,420; F.Paneth, Nature, 1927,119,706;A., 1927, 606.2. physikal. C'hem., 1928, 134, 353; 1928, B, 1, 170; A., 858, 1341.Ber., 1928, 61, [BJ 233; A., 269314 AXNUAL REPORTS ON TRB PROGRESS OF CIHICWSTRY.potassium carbonate and dissolution of the residues in water removedalmost all of the oxides of tantalum and niobium, whereas morethan 99% of the protoactinium remained with the insoluble basicoxides ; this demonstrates the great difference in basicity betweenthe pentoxides of tantalum and protoactinium.Further concen-tration showed that protoactinium was remaining quantitabivelywith the oxides of zirconium and hafnium. The isolat!ion of thefirst from the other two was effected either by dissolving the oxidesin warm dilute hydrochloric acid and precipitating the proto-actinium by oxalic acid, or by adding thorium oxide to the mixedoxides and precipitating it as oxalate.In the second case 70-90%of the protoactinium accompanied the thorium in this reaction;the thorium was subsequently removed as fluoride, and the proto-actinium finally precipitated from the fluoride by ammonia. Bythese processes, 2 mg. of protoactinium oxide (probably pentoxide)were obtained in a presumably pure condition, since its activitycould not be increased by a repetition of the process of concen-tration. This material has been used to determine the half-periodof the elernentf0 and will be used for an atomic-weight determin-ation and for a general study of the chemical and physical propertiesof the top member of the elements of group VA of the periodictable.*f The quantity of protoactinium present in uranium mineralsis found to be as much as 0.4 g.per g. of radium present.0. Hahn and A. von Grosse 42 have shown that in addition to itsprincipal radiation, the a-particle, protoactinium expels both@-particles and y-radiation, which are shown to be characteristicand not due to impurity. They find that the absorption coefficientof the f3-radiation in aluminium is 126 cm.-l. (Frl.) L. Meitner,43by photographing the p-particles in a magnetic field, has investigatedthe y-radiation emitted, and shown that there are three y-rays ofwave-lengths 0.13, 0.0419, and 0.0382 b. An interesting deductionis made from a consideration of the p- and y-radiation emitted byprotoactinium and other a-particle elements. It is pointed outthat the shortest wave-length of the y-rays associated with variouscc-particle changes is of the same order in all cases that have beeninvestigated, whereas with p-ray changes the variations may exceedfifty-fold.Hence it is concluded that the disarrangement of thenucleus produced by expulsion is of the same order for all a-particleemissions but varies widely for different f3-particle emissions. Fora-particle changes in the same disintegration series, the energy4O Infra, p. 319.41 0. Hdiri, fiitrung8ber. Preuss. Akad. Tl'i88. Berlin, 1927, 275; A,, 1928,343.42 2. P&8.L'k, 1928, 48, 1; A,, 609. 49 x a . , i928,60, 1s; A,, 1069SUB-ATOMSO PIFICNOMENA AND IWIDIOACTIVITY. 3 16associated with the y-line of shortest wave-length is greater thelonger the half-period of the element emitting it; the inverse isshown by p-particle changes.The atomic weight of protoactinium has yet to be determineddirectly.Hitherto the general opinion has been that members ofthe actinium series have atomic weights of the form 4n + 3 (wheren is an integer), the masses of the parent of the series, of proto-actinium, of actinium, and of the end-product being 239, 231, 227,and 207, respectively. A. S. Russell 44 has now departed from thisview. He shows, from F. W. Aston’s results for inactive elements,that the principal isotope of an element of odd atomic number isalmost always a mass one unit greater than the principal mass ofthe element next below it, and, from the results for the uraniumand thorium disintegration series, that an isotope which emits itp-particle has a greater mass than one emitting an a-particle.Itshould, therefore, be expected that 233 is the mass of protoactinium,if this be regarded as the principal isotope of element 91, and that227 cannot be the mass of actinium, but a number greater thanthis. On the basis of 233 and 229 for the atomic weights of proto-actinium and actinium respectively, those of the head of the series(at. no. 92) and of the end-product (at. no. 82) become 237 and209, respectively. This value for the uranium isotope is probablein view of F. W. Aston’s results for heavy inactive elements, whichshow that isotopes of masses 1 and 3 less than that of the principalisotope are often found in elements of even atomic number, whilstan isotope of a mass greater by unity is seldom or never found.The view, therefore, that the mass 239 is the head of the actiniumseries is very unlikely, and, in consequence, the difficulty of explainingwhy the immediate disintegration products, postulated by thisview, have never been discovered does not ari~e.~1145 The principalobjection to Russell’s view is that it gives for the mass of the end-product of atomic number 82 the value 209, a number which is notonly unlikely in itself but is at variance with calculations 46 fromatomic-weight determinations of uranium-lead, which lead to valuesof approximately 207 for the end-product of the actinium series.Reochroic Haloes, the Actinium Series, and ‘‘ Hibernium.”The interesting suggestion that the actinium series is independentof the uranium series has been made by S.Iimori and J. Yoshimura 47a8 the result of an examination of pleochroic haloes in some specimens44 Nature, 1927, 120, 402; A,, 1927, 1002.45 E. W. Walling, Dise., BerZin, 1928, 43.46 F. Lotze, 2. anorg. Chem., 1928,170, 213; A,, 084.4 7 Sci. Paper8 In&. Phy8. Chem. Ra. Tokyo, 1920,6, 11; A., 1926, 990316 ANNUAL REPORTS ON THE PROGRESS OF ~ ~ M I S T R Y .of Japanese biotite. Like J. Joly48 some years ago, they foundcertain haloes which could not be ascribed to members of theuranium or thorium disintegration series. These haloes possess acommon ring of radius 18.2 (which is that to be expected fromprotoactinium), other rings ascribed to members of the actiniumseries, no ring ascribable to members of the uranium series, butsometimes two very small rings of radii 10.0 and 5.9 p not unlikethe X-haloes of Joly (one of which he ascribed to the element‘‘ hibernium ”).The presence of actinium rings, unmasked by thoseof members of the uranium-radium series, is regarded as evidenceof the independence of the two series. Further, the two smallrings are ascribed to isotopes of uranium which precede proto-actinium in the series as originally postulated by A. Pi~card.~@As this view is a t variance with well-established chemical work, ithas been re-examined by A. S. Russell.50 He agrees with theattribution by the Japanese workers of the outside rings of thehaloes to protoactinium and its products, and with their view thatthe rings of smaller radius are probably identical with the X-haloesof Joly, but not with their other conclusions.He ascribes theformation of all abnormal haloes to the alteration of radioactiveminerals by agencies such as percolating water. Thus, since proto-actinium differs widely in chemical properties from the otherelements of a uranium mineral, it has been possibly separated in pasttime, with or without other products of the disintegration series,from the parent mineral, with the consequent formation of actiniumrings unmasked, as normally they are masked, by uranium-radiumhaloes. In continuation of this argument, the smallest of theJapanese workers’ rings is considered to be identical with Joly’shibernium ring, and these are considered to be caused by the feebleradioactivity of the end-product of the thorium series.The othersmall ring is considered to be identical with another of Joly’sX-rings, and to be caused by the feeble radioactivity of the end-product of the actinium series. The remaining rings are consideredto be due to protoactinium separated with or without lead from eitheruranium or uranium-thorium minerals. On this view, the dis-integration series are partly extended to mercury, and the elementhibernium is identified as thorium-0. Direct observation ofa-particles from the end-products of the thorium and actiniumseries has, however, not yet been obtained; the activity, if itexists, would be so feeble as to make identification of the particlesa, matter of great experimental difficulty.48 PTOC.Roy. Soc., 1922, [A], 102, 682.*% Arch. Sci. phys. W., 1917, 44, 161 ; Physikid. Z., 1022, 23, 1.O0 Nadure, 1927, 120, 645; A,, 1027, 1003SUB-ATOMIC PHENOMENA AND RAD1OACTI"Y. 317Possibility of the Existence of Elements 85 and 87.This question, which has become of added interest to chemistssince the discovery of the last of the undiscovered inactive elements,has been discussed by 0. Hahn51 and by G. von Aproduct of atomic number 87 (eka-czsium) might be producedfrom one of atomic number 89 emitting an a-particle or from oneof atomic number 86 emitting a p-particle. Hahn added a c d u mcompound to a strong mesothorium preparation and then removedall known radioelements from it by chemical treatment.If aproduct of atomic number 87 were there it would remain with theczesium, and if its half-period mere not shorter than 2 hours and ifa t least lo4 of the atoms of mesothorium-2 emitted =-particles it,would not have escaped detection. It was not, however, detected.Similar experiments with actinium were not tried owing to lack of5 sufficiently concentrated preparation. CT. von Heresy was unableto detect a-particles from mesothorium-2, the existence of whichnecessitates a product of atomic number 87, and concludes thatless than 1 in 200,000 atoms of mesothorium-2 breaks up in thisway. Trials to find a product of atomic number 87 as a @-productof radon by removing chemically all the known members of theactive deposit of 100 millicuries also failed.Preliminary experi-ments to find a product of atomic number 85 as a p-product of theshort-living isotopes of element 84 also gave negative results.It would seem from experiments of this kind that the existenceof elements 85 and 87 is going to be very hard to substantiate,and it may be asked whether present knowledge of radioactiveprocesses is favourable or not to the existence of these elements.Can it be said that it is in the highest degree unlikely that theseelements will ever be discovered on the earth? All masses ofatomic number greater than 83 are known to be radioactive, and,within the limits of atomic number 92-81, those of even atomicnumber are on the whole more stable than those of atomic numberone greater. It may, therefore, be presumed that no product ofelement 87 would have the period of radon, and no product ofelement 85 that of polonium. If this be granted, it is certain that,elements 85 and 87, created by the same cosmic process that broughtinto being the other elements, have long ago disappeared.Their onlychance of existence lay in their being members of one of the knowndisintegration series, but it is known that none of these passesdirectly through atomic number 85 or 87 or, as the experimentsmentioned above indicate, indirectly by forming branches. The51 Naturm*s8., 1926, 14, 159.52 Kgl. Daneke Videmkcch. 8d8k. mth.=fys. Nedd., 1926, 7, No. 11, 1 ;A,, 1927, 289318 ANNUAL REFORTS ON THE PROGRESS OF CfKEMTSTRY.case against the possibility of existence of these elements appearsoverwhelming save for one thing.It may be argued that we knownothing of the stability of the elements other than uranium andthorium greater in atomic number than 83, because they have neverbeen examined. Radium, for example, although the most stableisotope of element 88, is merely a disintegration product of theuranium series, and not the element 88 created by the process thatcreated uranium or lead or tin. This element, even if i t has themass 226, would not, except by a coincidence, have the tmmestability as radium, because such isobaric isotopes as are known inradioactivity differ in stability (e.g., uranium-2 and uranium-X2 ;radium-D and radium-a’). Hahn believes in the possibility ofmore stable isotopes of elements 88 and 84, and von Hevesy in thatof a stable isotope of element 84.So long as isotopes of elementsS8, 86, and 84, more stable than those furnished by the disintegra-tion series, are possible, so long is it possible to argue that some dayisotopes of elements 85 and 87 may be discovered. It should besaid, however, that none of these more stable isotopes has beendiscovered ; pleochroic haloes afford no evidence of them, and, inthe case of element 86, an exhaustive search made by F. W. Aston,53using the methods of positive rays, was without result. It maybe concluded that, whilst an investigation with comparatively enor-mous supplies of known radio-elements may demonstrate the exist-ence of these elements as branches of the main disintegration series,their independent existence in nature is very unlikely.Their rarityis probably so different in degree from that of the other recentlydiscovered elements as almost to be a difference in kind.Radioactive Constants and other Data.The conflict 5* regarding the value of the half-period of radium-Emay now be regarded as settled in favour of the higher value;L. F. C ~ r t i s s , ~ ~ in a new determina.tion, finds a value of 4.975 days,in good agreement with the results of G. N. Antonov, (Frl.) L.Meitner, and L. Bastings, but not with those of G. Fournier andK. Thaller. M. A. da Silva 56 obtained the value of 140.2 days forthe half-period of polonium, in good agreement with the acceptedvalue. A new determination by 0. Hahn and 0.Erbacher 57 ofthe half-period of rnesothori~zm-2 gives a value (viz., 6.13 hours)which is 1% less than the original value but 3% greater than that53 Proc. Roy. Soc., 1923, [ A ] , 103, 462; A , 1923, ii, 487.54 Ann. Report, 1926, 23, 293.5 8 Phyeical Rev., 1927, [ii], 30, 639; A,, 1928, 4.56 Compt. mnd., 1927,184, 197; A., 1927, 182.57 P h y d d Z., 1926,27, 631; A, 1926, 990SUB-ATOBIIU PHENOMENA AND RADIOACTIVITY. 3 19of W. P. Widdowson and A. S. Russell 58 and is probably the mostaccurate value. From a new relation between the disintegrationconstant and the quantum number of the element emitting thea-particle, Sir E. Rutherford 59 has deduced that the half-period ofuranium-I1 is less than that of ionium and is about 100,000 years.A smaller value than this (viz., 13,000 years) has been obtained byG.C. Laurence60 by applying the Geiger-Nuttall relation to hisnew determination, 3.28 em., of the range of the wparticles ofuranium-11. Both these values are much smaller than the hithertoestimated value of 2,000,000 years. In 0. Hahn's laboratory twoindependent estimates of the half -period of protoactinium havebeen made : A. von Grosse 61 has obtained it value of 20,000 yearsfrom a determination of the amount of pure protoactinium extractedfrom a known weight of uranium ore, and E. W. Walling 6a arriveda t the same result by measuring the rate of growth of protoactiniumin uranium originally carefully freed from it. From the resultthat the radioactivity of potassium is wholly or mainly to be ascribedto its isotope 41, the half-period of this isotope is deduced to be7.5 x 1010 years.63The initial velocities of the a-particles from radium-C, thorium-C',and thorium-C' have been determined by G.H. Briggs as 1-923 xlo9, 1.705 x lo9, and 2.053 x lo0 cm,/sec. respectively. The firstof these determinations is in excellent agreement with the originaldetermination by Sir E. Rutherford and H. Robinson,@ viz.,1.922 x lo9 cm./sec. S. W. Watson and &I. C. Henderson66 havedeterminsd the number of a-particles from thorium$ + C' as(4.26 & 0.08) x lo1* per sec. per curie-equivalent of y-ray activitywhen in equilibrium with radiothorium and when measured by they-rays from thorium-C" through 1.8 cm. of lead. S. W. Watson 6'has made a new determination of the heats emitted by radon inequilibrium with its products of short life, by radium3 + C ,radium-C, thorium-B + C, and by thorium-C. The results obtainedagree within 1 or 2% with the theoretical values calculated fromV.Hess and R. W. Lawson's 68 result for the number of a-particlesemitted per sec. by 1 g. of radium, viz., 3-72 x 1010, and renderthc lower value of H. Geiger and A. Werner O9 (3.4 x 1010) not58 Phil. Mag., 1926, [vi], 49, 137; A., 1025, ii, 463.6o Ibid., 1928, [vii], 5 , 1027; A., 684.62 Di88., Berlin, 1928.Proc. Roy. SOC., 1928, [A), 118, 549; A., 569.6 6 Proc. C a d . Phil. SOC., 1928, 24, 133; A., 214.6 7 Proc. Roy. SOC., 1928, [A], 118, 315; A., 455.68 Phil. Bag., 1924, [vi], 48, 200; A., 1924, ii, 649.69 2.PhpaiE, 1924, 21, 187; A., 1924, ii, 226.Ibid., 1927, [vii], 4, 580; A., 1927, 1002.Ber., 1928, 61, [BJ, 233; A,, 269.* j A., 1014, ii, 789.63 Supra, p. 309320 ANNUAL REPORTS ON THE PROGRESS OF OHEMISTBP.impossible but unlikely. They are as follows (observed values ing.-cal. per g.-hr. precede calculated values) : radon 101.6, 102.4;radium-B + C 43.1, 43.8; radium4 42-9, 43.4; thorium-B + C60.7, 49.7; thorium-C 47.9, 47.2. Support for the lower value,however, is afforded by the results of H. Jedrzejowski,70 whodetermined the mean value of the total charge of the =-particlesemitted in 1 sec. by 1 g. of radium as 33.4 E.S.U. ; hence thenumber of a-particles emitted per sec. by 1 g. of radium is 3.50 x1010.(Mlle.) I. Curie and F. Joliot 71 have determined the numberof ions produced by a single a-particle from radium-C.' and findthe value 2.2 x lo5, assuming 3.7 x 1O1O as the number of a-particlesemitted per sec. by 1 g. of radium. A. Holmes and R. W. LawsonY72after a critical review of the available data, give two formulE (oneapproximate and one corrected) for calculating the ages of radio-active minerals from a knowledge of their percentage composition.The approximate formula is : Age (years) = 7-4 x lOQ Pb/(U +0.38 Th), where Pb, U, and Th denote the yo of lead having radio-active origin, of uranium, and of thorium in the mineral. Thecorrected age is : Approximate age x (1 - x / 2 + x2/3), wherex = 1.155 Pb/(U + 0.38 Th).Radioactivity and Solar Radiation.The remarkable observations by (Mlle.) S.Maracineanu describedand commented on in the last Report73 have been ~ontinued.~4Lead, zinc, and copper after exposure to the sun, and lead afterbeing subjected to positive and negative voltages of 120,000, werefound to acquire a radioactivity which cannot be explained as dueto emanation or active deposit in the atmosphere. It is concludedthat lead, insolated for a SufEciently long period, produces a newradioactive substance which emits a-particles and is not unlikepolonium in its half-period. It is suggested that under the influenceof the sun polonium and even radium-D are integrated from thelead. These experiments have yet to be repeated by other observers,and until this is done and the results are confirmed it is probablywiser to ascribe them to less interesting but more natural causes :to an effect of the sun on the surface of the lead so that radioactiveimpurities therein have their radiations temporarily less stronglyabsorbed, to the presence of radioactive substances in the atmo-70 Compt.rend., 1927,184, 1551; A., 1927, 710; Ann. Physique, 1928, [x],'1 Compt. rend., 1928, 187, 43; A., 810.72 Nature, 1926,118, 478; A., 1926, 1075.73 ,41m. Report, 1926, 23, 394.74 Conqt. rend., 1027,184, 1383, 1547; 185, 132; 1921,186, 746; A,, 1927,9, 128; A,, 343.606, 710, 807; 1928, 466SUB-ATOMIC PHENOMENA AND RADIOACTIVITY. 32 1sphere, and to the daily variation of the natural leak of the measuringinstrument. The observations are not unlike those of “inducedactivity ” which were common in the literature about 27 years ago.The fact that the effects have been observed with zinc and copper,as well as with lead, may be taken as conclusive evidence that theyare not due to any fundamental action of the sun’s rays on theatoms they strike.On modern views of the structure of the atomit seems impossible that solar radiation could produce poloniumfrom lead.Cosmic Rays and Stellar Matter.Work on the penetrating extra-terrestrial radiation has beencontinued 75 by R. A, Millikan and G. H. Cameron 76 and, althoughnecessarily speculative, results of great interest have been obtained.Experiments with pilot balloons show that it is unlikely that thereare radiations intermediate in wave-length between y-rays and thecosmic rays. Definite bands in the cosmic-ray spectrum are found,and these are produced, it is suggested, by definite and continuallyrecurring atomic transformations which involve energy changesaltogether of a much greater magnitude than those which occur inradioactive processes; they are not likely to be caused, therefore,by such processes. Their most likely source is the building up ofhelium from hydrogen, of oxygen from hydrogen, and of siliconfrom hydrogen or from helium. The calculated absorption co-efficients per metre of water of the rays produced by the first threeof these processes are, respectively, 0-30, 0-075, and 0.043, andthere is experimental evidence that the cosmic rays include radi-ations having absorption coefficients per metre of water of 0.35,0.08, and 0.04. From the close similarity of these sets of values,it is concluded that there is continuous creation of helium, oxygen,and silicon in the universe out of protons and electrons. In a laterpaper 77 further points are discussed. As to the place of origin ofthe cosmic rays, it is concluded from kinetic and other evidencethat the nuclear combinations which produce them do not takeplace in the stars, as has hitherto been imagined, but a t places oflow pressure where the temperature is not far from the absolutezero : in interstellar or intergalactic space. There the radiationfrom the stars is converted, under the conditions of zero temperatureand zero density, into protons and electrons, and there the commonelements are built up. This bold assumption appears to removemany dBiculties. Gone is the difficulty of explaining why theprotons and electrons which produce the cosmic rays have not long75 Ann. Report, 1926, 23, 294.76 Proc. Nat. Acad. Sci., 1928, 14, 445; A., 811.77 Physical Rev. 1928, [ii], 32, 633; A., 1303.REP.-VOL. XXV. 322 AXNUAL REPORTS ON THE PROGIRESS OF OHEMISTRY.ago been used up; nor is there now need to suppose, as has beendone, that the process of conversion of mass into radiant energyis either nowhere reversible or everywhere reversible. With thestars in one place and interstellar space in another, each functioningappropriately, one's loss is the other's gain, and the universe maybe regarded as being now and forever in a steady state. Suchrevolutionary views are not likely to obtain universal acceptancefrom physicists and astronomers, and critical discussion of themhas begun.'8A. S. RUSSELL.78 Sir 33. Rutherford, Proc. Roy. Soc., 1929, [ A ] , 122, 1

ISSN:0365-6217    

DOI:10.1039/AR9282500303

出版商:RSC    

年代:1928

数据来源: RSC

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CATALYSIS.IN accordance with the tendency exhibited in Annual Reports ofrecent years, we have attempted rather to survey the literature inparticular fields germane to the subject of Catalysis than to attemptto prepare a complete abstract of all the varied communicationsmade on the subject during the period under review.Low- temperature Oxidcct ion.Catctlysts and Inhibitors.-The study of low-temperature oxidation,autoxidation, and antioxygenic action has received much attentionduring recent years. Two valuable summarising papers haverecently appeared.l*Attention was called at the General Discussion of the FaradaySociety on Homogeneous Catalysis to a number of points in con-nexion with these phenomena and their explanation as chainreactions. As a result of the very large number of experimentson low-temperature oxidation and inhibition C.Moureu and C.Dufraisse have shown that substances may possess both pro-oxygenic and antioxygenic activity, though the former is notgenerally very intense, and they differentiate between these sub-stances-iodine, for example, with styrene-and those substanceswhich, although as a rule practically inert towards oxygen, areoxidised in the presence of a catalyst which is itself fist oxidised,as, for example, the oxidation of dextrose in the presence of ceriumsalts (Job, 1900). In many cases a catalyst may have either onefunction or the other in the same or different reactions.The question a t once arises as to whether the action of anti-oxygens may not be due to their destruction of positive catalysts,which are almost certainly present. The apparent necessity fortraces of water in certain reactions would support the necessity ofsome such catalyst.According t o Moureu and Dufraisse, Titovshowed that the inhibitory action of benzyl alcohol, etc., on theoxidation of dilute sulphite solutions acted in this way, and otherexamples may be cited. Where the reaction proceeds on the wallsor on a surface, there can be no doubt that an inhibitor can poisonthe necessary active areas and thereby stop the reaction, as was1 J . SOC. Chem. Ind., 1928, 47, 819, 848.a H. L. J. Biickstrom, Medd. K . Vetenskapsakad. Nobel-Inst., 1927, 6, 16 ;A., 1927, 1161324 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.shown by M.Brunner? 0. M. Reiff,4 and E. K. Rideal and (Miss)W. M. Wright.5 The extraordinary efficiency of small traces ofpositive catalysts can be noticed in the experiments of R. Kuhn andK. Meyer,6 who have shown that very carefully fractionated benz-aldehyde, in a carbon dioxide atmosphere, can, when the greatestprecautions are taken, be made inert to oxygen. The action isimmediately induced by the presence of exceedingly small amountsof heavy metals, iron, copper, nickel, and manganese salts allbeing effective, the iron being 15 times more active in the ferrouscondition than in the ferric; inhibition by phenol is prevented byiron salts. It seems impossible to account fully for all the factson this hypothesis. Moureu and Dufraisse, with many otherauthors, believe that the first step involves the union of one moleculeof oxygen with one of the autoxidisable substance to form theprimary peroxide, A[02], and that energy is absorbed in this process,so that only active molecules can undergo the change.The primaryperoxide will then possess a very high energy, sufficient to oxidisethe antioxygen B. Their scheme for antioxygenic action is thenA + 0 2 + A[O,IA[O,I 3- €3 --+ 4 9 1 + BPI401 + B[OI --+ A + B 3- 0 2 ,or a similar stage involving the direct oxidation of B to B[OJ andits subsequent decomposition. The action of the negative catalystis therefore a positive one in the direction of the reverse reaction.These schemes are worked out very fully and explain the closerelationship between positive and negative catalysts and the easychange from the one to the other.This rise in potential of theactive molecules which may then be lost either to the initial stateor to the stable state of oxidation has been shown by these authorsto be thermodynamically sound,' and they have applied theirresults to the preservation of rubber and other easily oxidisablesubstances.In the papers quoted above, the objections raised by F. Perrin 8have been discussed. Perrin's views, based principally on fluor-escence effects, are briefly that the deactivation of an excitedmolecule is due to a free electron, such as might be found in anHelv. Chim. Acta, 1927, 10, 707; A., 1927, 1152.J . Amer. Chem. Soc., 1926,48, 2893; A., 1928, 57.J., 1927, 2323 ; and earlier papers.C. Moureu and C.Dufraisse, Compt. rend., 1927, 185, 1546; 1928, 186,Compt. rend., 1927, 184, 1121; A., 1927, 609. (See also J. Perrin, ibid.,13 Naturwiss., 1928, 18, 1028.196; A., 251.1928, 187, 913, on the relations of light in a thermal chemical reaction.CATALYSIS. 325easily oxidisable substance such as an antioxygen. A chain theorysimilar to Bodenstein’s is regarded as the most probable mechanism ;the reacting molecule is supposed to have sufficient energy to causeother molecules to react, and the diminution of the mean lives ofthe reacting molecules by the inactivating molecules lessens thechance of reaction of the former. Thus antioxygens may inhibitphotochemical reactions which are not necessarily oxidations.Thequestion of the reaction chain will be dealt with in greater detaillater. Moureu and Dufraisse believe that these catalysts behaveas antioxygens and antiluminants on account of two separateinfluences, and a theory which connects up the two effects cannotbe reconciled with the inversion of catalysis in an autoxidation,and the relationship of inverse catalysts. The work of H. Gaffron ’is explicable by assuming the formation of a primary peroxide,containing active oxygen only, followed by its catalytic destructionwith the liberation of oxygen.In two recent papers 10 Moureu, Dufraisse, and M. Badoche haveexamined the inhibition by phosphorus and its compounds; 1%of this element can inhibit the autoxidation of furfuraldehydewhilst increasing that of benzaldehyde, styrene, or turpentine.Red phosphorus may also act, although less strongly, in eitherdirection. Investigations have also been made on phosphorustrichloride, tribromide, oxychloride, and oxybromide, and onhypophosphorous, phosphorous, and phosphoric acids ; and theresults support the view that an oxygenating catalyst must be ableto undergo further oxidation.Moureu, Dufraisse, and J. R.Johnson l1 have published a series of papers on the autoxidationof furylethylene and have examined the effects of numerous inhibit-ing agents. With G. Berchet,12 these authors have also studiedthe autoxidation and polymerisation of chloral, and the effect ofsmall quantities of impurities. The low-temperature oxidation inthe presence of oxygen is autocatalytic, depending on the initialformation of a catalyst in the light, after which the reaction canproceed in the dark.Substances such as phenols, etc., and anti-oxygenic catalysts in general also inhibit the spontaneous poly-mensation to metachloral. Moureu, Dufraisse, and Badoche l3 haveexamined the inhibiting effect of arsenic and its compounds onautoxidation. Arsenic compounds may be positive or negativecatalysts .Biochem. Z., 1926, 179, 157; A., 1927, 1226.lo Compt. rend., 1928,186, 1673; 1928,187, 157; A,, 849, 967.l1 Bull. Soc. chim., 1928, [iv], 43, 586; A., 718.l2 Ibid., p. 942; A,, 1196.l3 Compt. rend., 1928, 187, 918326 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Intermediate Cmpounds.Van der Beek l4 has published two papers on the autoxidationof benzaldehyde in the presence of various catalysts, describingattempts to isolate the intermediate product, perbenzoic acid.As much as 43% of this acid was isolated from an acetone solutionafter exposure to sunlight and oxygen, and the reaction in benzenesolution is believed to bePh-CHO + Ph*CO,H,Ph.CO3.H + Ph*CHO .+ 2Ph*COzH,but this mechanism cannot obtain in carbon tetrachloride solution.The intermediate products in presence of acetic anhydride werealso examined.H.N. Stephens l5 has similarly isolated the peroxide formed inthe low-temperature oxidation of cyclohexene : the product wasapparently a dimeric form of the peroxide containing one peroxidegroup, and about 0.75% was formed in four months.I n continuation of his researches, Wieland l6 has examined theenzyme which causes the autoxidation of quinol, and also theperoxidase obtainable from horse-radish; and H.Wieland and W.Frankel' have made a very complete study of the activation ofoxygen by ferrous salts in solutions.The induction period of the autoxidation of n-hexane has beenshown by M. Brunner and E. K. Rideall8 to be similar to that ofbenzaldehyde, and is due to the formation of a peroxide whichmust reach a certain concentration before the rapid oxidation,believed to be due to a chain mechanism, is started. The relationof the temperature and the oxygen pressure to this period wasexamined, and also the surface combustion on pumice wherebypolymerisation products from the decomposition of the peroxidemolecules are believed to be formed.More recently, these authors l9and Brunner alone2* have examined the reaction in greater detailby freezing out the reaction mixture at stated intervals and examin-ing the products. The induction period is shown definitely to beaccompanied by a rapid rise in peroxide or moloxide concentration,which attains a maximum at the same time as the rapid oxidationbegins, as measured by the pressure decrease of oxygen. Thatsome slow reaction is also taking place during the induction periodwas shown by the increasing concentration of carbon monoxidel4 Rec. truv. chhn., 1928, 47, 286, 301.l6 J . Amr. Chem. Soc., 1928, 60, 668; A,, 401.l6 H. Wieland and H. Sutter, Ber., 1928, 61, [B], 1060; A., 921.17 Anden, 1928, 464, 101; A., 965.18 J., 1928, 2824; A,, 1360.l8 J., 1928,1162; A., 731.2O Helv.Chim. Actct, 1928, 11, 66CATALYSIS. 327and carbon dioxide and at the same time the fatty acid concen-tration rises to a steady value which is reached at the same timeas the rapid reaction begins. The amount of water formed risescontinuously during the f i s t part of the reaction, while the oxygenpressure is falling rapidly. The general reaction schemes proposedby Brunner are the primary reaction2C6H14 + 0, -+ 2C,H12 + 2H20,and the moloxide decomposition(c6H14)2(02) 2C6H12 2H20(cf3H14)(02) C5H11*m0 + =Aowhilst the peroxide may reactC5HI1*CH,*O*OH __+ C,Hl1*CHO + H20,C,Hll*CH2*O*OH + CGH,, a-> 2C6H1, + 2H20.(acceptor)The presence of small amounts of oxides of carbon and thegeneral complexity of the reaction, together with the concealedrapid reaction in the “induction period,” point to this reactionbeing much more complex.than was originally supposed, and showthat direct pressure readings of the total pressure may give com-pletely misleading results. F. Oberhauser and W. Hensinger 21have noted the production of an activated form of oxalic acid withpotassium permanganate, which had the character of an unstableperoxide but was not isolable. Several reactions hitherto regardedas purely homogeneous have been shown to be complex; thussome mutarotations are now known to be sensitive to the presenceof the walls of the apparatus, the most recent case being that oftetra-acetyl glucose in ethyl acetate.22 By use of a very finetechnique for the production of clean solutions and surfaces, com-plete arrest of the mutarotation was possible, and there was evidencethat with an alkaline catalyst the reaction might be due to thecontaminated surface of the vessel, and the progressive accelerationto some sort of chain mechanism spreading from the surface throughthe reagents.K.C. Bailey 23 has examined a similar case, namely, the inhibitionby pyridine of the esterification of ethyl alcohol and acetic acid;the reaction is found to occur partly on the walls and partly in thebulk phase, and inhibition may be due to the normal poisoning ofthe active centres.21 Ber., 1928, 61, [B), 621; A,, 505.22 T.M. Lowry and G. G. Owen, Proc. Roy. SOC., 1928, [ A ] , 119, 606; A.,967.1s J., 1928, 1204; A., 718328 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,E. Puxeddu% has discussed the previous work on induction inaqueous solutions, and concludes that these phenomena can all beexplained only by postulating an initial period of retardation in allchemical reactions, which in ordinary circumstances is very short.The induction period of the precipitation of sulphates of alkaline-ea,rth metals and of sulphur from thiosulphate by sulphuric acid isshown to be shortened by a rise of temperature or an increase inconcentration.In his studies of silver-ion catalysis, C. V. King 25 has also shown,inter alia, that the oxidation of the persulphate ion is stronglycatalysed, and that duplication of the results is very difficult,owing to some catalytic effect of the walls : it would appear thatthis factor in homogeneous liquid reaction may be more commonthan is generally recognised.H. Moureu 2* has also called attentionto the catalytic action of the glass in a study of the isomerism ofcertain a-diketones, in particular methylbenzylglyoxal and phenyl-benzylglyoxal, for which he shows the isomerism to be particularlymarked, with a tautomerism greatly affected by catalysts.(Miss) W. M. Wright and E. K. Rideal 27 have made quantitativestudies of the decomposition of hydrogen peroxide on various sur-faces, including glass, showing that the rates of decompositionattain a maximum when the electrometric potentials of the surfacesare brought to zero, thus permitting of a maximum absorption ofthe peroxide. B.H. Williams 28 has also studied the same reactionin glass, silica, and waxed vessels, and has shown the decompositionto-be due to adsorbed molecules on the walls or on dust, and par-ticularly on preformed active points on both glass and silica.Chain Reactions.Christiansen, in a note communicated to the Faraday Societydisc~ssion,~~ has criticised the general theory of Moureu andDufraisse on the action of inhibitors and oxidation on the maingrounds that all their experimental facts are not explicable on thisbasis. By an analysis of their mechanism, and by examining thevelocity coefficients of both the forward and the reverse reaction,he has shown that on their mechanism the addition of B, theinhibitor, could never decrease the velocity of the reaction.That,with the addition of a chain mechanism, their results are readily24 Gazzetta, 1928, 58, 95; A,, 484.25 J . Amer. Chem. SOC., 1928, 50, 2080; A,, 964; and earlier papers,26 Trans. Faraday SOC., 1928, 24, 562; A., 1334.2 7 Ibid., p. 530; A., 1196; Wright, ibid., p. 539; A., 1196.2 8 Ibid., p. 245; A., 598.29 J. A. Christiansen, ibid., p. 714C!ATALY SIS . 329explicable is well known, and, in particular, H. L. J. Blickstrom,30who has made some very exhaustive studies on autoxidation,inhibition, and the effect of light on these phenomena, has shownthat reaction chains here are necessary. In his earlier papers avery complete account is given of the formation of the reactionchains.He adopts Christiansen’s “ hot molecule ” hypothesis forthe production of thermal chains and shows that chains excitedphotochemically have substantially the same properties. Quantum-efficiency measurements of the length of the chain were made andshown to give a quantum yield of the order of 10,000 to 50,000 mols.per quantum for the photochemical autoxidation of certain alde-hydes. This necessarily implies that, when benzaldehyde and theper-acid react under the influence of light, other aldehyde moleculesare activated, and the inference is drawn that the thermal reactionproceeds in the same way.The autoxidation of sulphite solution is similarly studied, and itis shown that all the effects can be accounted for by assuming achain reaction occurring in two stages.A very complete discussionis given in the papers cited above. Of particular interest is hisdiscussion of the relationship of chemiluminescence and autoxid-ation, of which a complete bibliography is given, and the conclusionsreached are that, as believed by Christiansen, a newly formedreaction product molecule has the energy of the heat of reactiontogether with the energy of activation, and on collision with anothermolecule, if they are both rigid, the energy will be dissipated in theform of heat or kinetic energy ; but there is also the possibility thatthe collision may result in the excitation of one molecule (or evenmore in the case of autocatalytic reactions) to a higher quantumlevel, which with appropriate restrictions may revert to the normallevel with the emission of light.The results of H. Beutler, S. vonBogdandy, and M. P618nyi 31 (see also p. 333) are shown to be inagreement with this. Further, this must lead to photochemicalreactions, and the particular case of the decomposition of ozone isexamined in detail.The autoxidation of benzaldehyde, heptaldehyde, and sodiumsulphite, which Backstrom himself had studied, are shown to givesupport to this idea, and photo-sensitisers for these reactions are alsoinvestigated. Backstrom criticises Moureu and Dufraisse’s scheme 3230 J . Amer. Chem. Soc., 1927, 49,714; A,, 1927, 737; 1Medd. K. Vetenskaps-akad. Nobel-In&., 1927, 6, Nos.15, 16; A., 1151; Trans. Faraday SOC., 1928,24, 601; A,, 1335.31 Naturwiss., 1926, 14, 164.32 Moureu and Dufraisse, Compt. rend., 1922, 174, 258; A., 1922, i, 250;Bull. SOC. chim., 1922, 31, 1152; A., 1923, i, 91; Moureu, Dufraisse, andBadocho, {bid., 1924, 35, 1591, 1564, 1672; A . , 1925, i, 362, 363.L 330 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.for the autoxidation of acraldehyde, and considers that the factsare better explained on a chain hypothesis, with photochemicalside chains. In dealing with the action of inhibitors, he showsthat, as pointed out by Schonbein, by Moureu and Dufraisse,and by Dhar, an inhibitor of an autoxidation must in general havethe properties of an easily oxidisable substance, and his view isthat the inhibitor acts by reacting with the per-acid and reducingthe number of chains started.It is not completely establishedthat inhibitory power is due to oxidisability, and in the cases wherethis is not so, the inhibiting agent is stated to act by removingactivated molecules of, say, aldehyde, and thus breaking the photo-chemical chain. The work of F. Perrin (Zoc. cit.) may be cited forcomparison.In his most recent paper, Backstrom 33 has confirmed his view ofthe relationship between inhibition and the induced reaction.Using isopropyl, sec.-butyl, and benzyl alcohols as inhibitors, heexamined the oxidation of sulphites, and by means of colour testsdetected the presence of small amounts of acetone, methyl ethylketone, and benzaldehyde, as he expected.A very interesting result of this investigation was that the thermaland photochemical chains had sensibly the same length of about60 molecules.The inhibitory effect is expressed as the sum of twofactors-the breaking of the chains and some other factor-and aquantitative expression is obtained.N. R. Dhar,= in a summary of negative catalysis in slow reaction,has restated his position and added more work. The hypothesisof ion formation will be treated later in greater detail (see p. 343),and he considers that the high quantum yields obtained by Bkck-strom can be satisfactorily explained by the generation of ionswithout postulating any chain mechanism. In the thermal oxid-ation reactions, the negative catalyst acts by actually taking upoxygen and being oxidised, and consequently the two reducingagents compete for the oxygen.The present position of the theory of chain reactions has beenfully dealt with by Christiansen.35 He emphasises the fact thatwhere a small amount of substance has a great effect on the reaction,that reaction must be complex, so that one of the intermediateproducts is to a relatively great extent removed by the foreignsubstance.The possible velocity equations are generalised, andshown to have wide applications.33 Trans. Paraday Soc., 1928, 24, 601; A., 1335.34 Ibid., pp. 665, 667; A., 1336.35 Ibid., p. 596; A., 1335CATALYSIS . 331Low-temperature Fktrnes.The slow oxidation of phosphorus and the accompanying glowhave received a great deal of attention, particularly in the light ofthe very interesting work of N.Semenoff.36 It is well known thatyellow phosphorus glows in air, but not in oxygen unless the pressureis reduced below a certain value; it has also been shown that thereis a lower limit of pressure below which the reaction will not proceed.The glow has been examined spectroscopically,37 and the reactionis found to be sensitive to the light it emits. In a solution incarbon tetrachloride, Backstrom found a chain length of about30 molecules per quantum. The presence of ozone is also wellknown, and this points to the existence of excited molecules ofoxygen as well as of phosphorus. The work of (Lord) Rayleigh3*on the effect of moisture in extinguishing the glow led him to attributethe effect to the failure of the process causing propagation.Thepresence of ions in this reaction is stated by Busse 39 to be entirelysecondary, and he showed that only 1 ion was formed in 8,000,000reacting molecules; he also found ions in some cases carrying 8negative charges.J. Zawidski 4O has developed equations from Russell’s 41 valuesfor the velocity of reaction between white phosphorus and oxygenof various degrees of dryness and of various nitrogen contents.J. Chariton and Z. Walta42 studied the effect of inert gases and ofchange of pressure, and observed the critical minimum pressure.They suggest that the reacting molecule is P,, which on reactionliberates heat, thus producing more P2 from P4 molecules; this,together with the loss of energy by radiation, prevents the veryrapid propagation.M. Bodenstein criticised both the techniqueand the conclusions, but the criticisms have been met by Semenoff ,36who considers that Bodenstein’s deductions are incorrect. If it isregarded as established that a critical pressure exists below whichreaction is very slow, and which depends on the partial pressuresof the phosphorus vapour and of the admixed inert gas (e.g., argon),on the diameter of the reaction vessel, and on the temperature,Semenoff shows how the results may be interpreted best on hisoriginal branched-chain idea, the chain being broken on the walls.It is assumed that the reaction Pa --+ Pz is not instantaneous, thats6 2. Physik, 1927, 46, 109; A,, 1928, 483.37 H.Zocher and H. Kautsky, Trans. Faraday Soc., 1926, 21, 691 ; H. J.EmelBus, J., 1925, 127, 1362; A., 1925, ii, 740.38 PTOC. Roy. Soc., 1923, [A], 104, 322; A., 1923, ii, 755.39 Ann. Physik, 1927, 82, 873; 83, 80; A,, 1927, 633, 708.40 2;. physikal. Chem., 1927,130, 109; A,, 1927, 1149.41 J . , 1903, 83, 1203.43 Ibid., 1927, 41, 548; A., 1927, 326.42 2. Physik, 1926, 39, 547; A., 1927, 122332 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.the reacting molecules are activated and may lose energy by collisionwith the walls, and that the reaction is a chain proceeding very slowlyon account of the small number of active centres. It would becomeexplosive in the conditions calculated by Christiansen and Kramers.In a very recent paper, Semenoff 44 has studied the oxidation ofsulphur vapour, which he finds to behave in sensibly the samemanner as phosphorus.Since the induction period is removed bythe addition of ozone, he suggests that the active centres are probablyoxygen atoms.This would seem an appropriate place to mention the veryinteresting work of Hinshelwood and Bogdandy and Pblhnyi.C. N. Hinshelwood and H. W. Thompson45 have examined thereaction between hydrogen and oxygen over wide limits, from theheterogeneous wall reaction to the explosion point. Up to 500",the results are seen to agree with those of Bone and Wheeler,46the reaction being accelerated by powdered silica and retarded bysteam. From 520" to 530" a reaction of approximately the fourthorder, but which varies with the conditions and is strongly auto-catalysed by steam, becomes important, and in this reaction thewalls have an inhibiting effect. The reaction is accelerated by theaddition of nitrogen, or of an inert gas 47 which would lengthenthe chain, and this higher-temperature reaction is considered to bea truly gaseous reaction.These authors have no doubt in thisreaction as to the reality of the chains, which are lengthened by theelastic collision with the inert gas, or are broken at the walls as in thehigh-temperature reaction. The latter effect, it is suggested, mightbe due to the destruction of an autocatalyst for the principal reaction.A most interesting further study has been made of the results ofadding traces of nitrogen peroxide to the reaction mixture.H. B.Dixon observed that a t,race of this gas lowered the ignition tem-perature of hydrogen in air by some 200". C. H. Gibson andC. N. Hinshelwo~d,~~ in studying the reaction, observed a slowcatalysis which was explicable on the alternate oxidation and reduc-tion of nitrogen peroxide, but a t about 400" (or some 200" belowthe explosion temperature) a definite amount of the gas will causeexplosion, and there is a definite lower limit for the amount. Atthis temperature the normal wall reaction is very slow and if alarger amount of nitrogen peroxide is admitted an equally definite44 N. Semenoff and G. Rjabinin, 2. physikal. Chena., 1928, [B], 1, 192; A,,45 Proc. Roy. Soc., 1928, [ A ] , 118, 170; A., 483.4 6 Phil. I'runs., 1906, [ A ] , 206, 1.47 C.H. Gibson and C. N. Hinshelwood, Proc. Roy. SOC., 1928, [ A ] , 119,48 Truns. Furuday SOC., 1928, 24, 559; A., 1334.1332.591; A., 960CATALYSIS. 333upper limit is reached beyond which only this slow wall reactiontakes place. That this is not a catalysed reaction in the ordinarysense is shown by these two sharp limits. These two limits areshown to converge and should meet at about 350°, where thereshould be only one concentration which would cause the explosion,and experiments made to test this supported the view to some extent.This strong effect of a relatively small trace of a foreign substanceis believed to be purely a homogeneous one. The nitrogen peroxidemay cause the reaction to proceed much faster and behave as asort of detonator, for if sufficient heat is produced in a volumeelement of the gas, explosion will result.The upper limit may bedue to a falling-off of this detonator reaction or to a dissipation ofthe heat produced by the nitrogen peroxide itself. Gibson andHinshelwood make the point that, since the reaction at 530-580"in the absence of the peroxide is quite rapid, it will proceed withouta catalyst ; and by analogy, the thermal decomposition of ammon-ium chloride may proceed in the absence of water, which behavesin the same way. This is not evidence for the existence of un-catalysed reactions, but is nevertheless a strong point. H. F. Cowardand F. J. H a r t ~ e l l , ~ ~ in a preliminary communication, stated thatthe lower limit of upward hydrogen flame propagation was but littleaffected by the presence of nitrogen peroxide, nor was.the downwardpropagation in methane, thus suggesting that a surface phenomenonmight be the determining factor.Methane did, however, show amarked decrease in the upward propagation, although not as muchas might have been expected. A. C. G. Egerton,50 in discussingHinshelwood's results, suggests that the reaction may be explainedon lines analogous to Semenoff's reasoning : the nitrogen peroxideundergoes a reaction and produces a number of thermally activatedreaction centres, which can then promote chains throughout thegas, and if a sufficient number are produced explosion will occur.The suggestion was made that the higher limit might be due tosome reaction product acting as an inhibitor, but it is difficult tosee why a sharp limit should be expected on this view.R. N.Pease and P. R. Chesebro 51 have examined the slow combustionof methane, hydrogen, and isobutane in Pyrex-glass tubes, andconclude that reaction centres develop in the body of the gas andthat not only does glass packing decrease the volume of free spacenecessary for the development of the reaction centres, but also thatthese are deactivated on striking the glass.Pbkinyi and others 52 have made a study of chemically induced4D Trans. FarcMEcay Soc., 1928, $34, 703. b0 Ibid., p. 697.5 1 Proc. Nat. Acad. Sci., 1928, 14, 472 ; A,, 845.52 M. P616nyi and S. von Bogdandy, 2. EZektrochem., 1927, 33, 554; A.,1928, 373; M.P616nyi and H. Beutler, Natumuiss., 1926, 13, 1711334 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.chain reactions. Hydrogen containing a small quantity of sodiumvapour, acquired by passage over the molten metal, was led intochlorine, whereby some sodium chloride was formed and a con-siderable quantity of hydrogen chloride. This result is consideredto be due to a reaction chain similar to the Nernst photochemicalreaction chain :Na + Cl, -+ NaCl + C1,C1+ H, -+ HCl+ H,H + C1, + HC1+ C1. . . . .The chain length is estimated to be 700--10,000 molecules. Increasein sodium vapour pressure decreases the length of chain, butimpurities and the glass walls have a very large effect. Potassiumgave similar results with shorter reaction chains, and with methane,methyl chloride was formed, but the chain length was reduced to100-300.The inhibiting effect of bromine was noticed and dis-cussed more fully in a later paper.% The atom chain is consideredto be broken by the bromine combining with the hydrogen atom,and an analysis of the chain length supports this view.Induction by bivalent metals is of particular interest. The directreaction Mn + C1,+ MCI, does not take place, but ratherMI1 + Ch+ MC1+ C1, and thus the chain is started. It wasshown in a rather ingenious manner that the chain was not startedby the activated MC1, molecule, although some MCI, is formed inthe case of zinc. Cadmium causes less induction, for a greaternumber of atoms reach the wall without reacting with chlorine andthere form cadmium chloride with no activation.Altering thepressure of hydrogen and admitting nitrogen confirmed this viewand probably the reaction between Zn (or Cd) and c1, does not, likethat with sodium, take place at every collision. A study of theenergies of activation and the heats of formation of the monochloridesled to the conclusion that these were sensibly the same, a furtherproof of the correctness of the mechanism.The chemiluminescence of the " highly dilute flames " of sodiumin iodine, chlorine, and mercuric chloride has been examined byvarious workers.54 The theory outlined above and the kinetics63 M. P6lAnyi, Trans. Faraday SOC., 1928, 24, 606 ; A., 1336.64 M. P61Qnyi and G. Schay, 2. physikal. Chem., 1928, [B], 1, 30 ; A,, 1339 ;2.Phyaik, 1928, 47, 814; M. P6lhnyi and S. von Bogdandy, 2. phyeikaz.Chem., 1928, [B], 1, 21; A,, 1339; M. P6lhnyi and H. Beutler, ibid., p. 3 ;A., 1331 ; H. Ootuka, and G. Schay, ibid., p. 62; A., 1339. (It may be notedthat J. M. Walter and S. Barratt, Proc. Roy. SOC., 1928, [A], 119, 257; A.,812, end D. S. Villars, PTOC. Nut. Acad. Sci., 1928, 14, 509; A., 1165, haveproduced evidence showing that sodium vapour at lower temperatures islargely diatomic.CATALYSIS . 335and energy relations are further developed, as also is the reactionwith diatomic sodium va,pour. The heat of dissociation of sodiumis calculated from the results to be 18 & 2 kg.-cals. It is nowcertain that the reaction K + I (or Na + I) can only take place onthe surface and not in the bulk phase.V.Kondrateev 55 has studied the reaction between sodium orpotassium vapour and cupric chloride or bromide vapour at 300”.The light emitted has the same spectrum as the correspondingcuprous halide, and the reaction is believed to be a wall reactionbetween solid cupric halide and gaseous alkali metal giving solidalkali halide and gaseous cuprous halide. The reaction betweensodium and mercuric chloride vapours is now definitely proved tobe homogeneous. It may be noted that Wanklyn’s original experi-ment 56 (compare Cowper 57) on the distillation of sodium throughdry chlorine without reaction has been repeated and confirmed,thus presenting afresh the problem of the origin of the necessaryreaction centres for these chain reactions.Combustion and Flumes.A number of papers on this subject deal with catalytic reactions,e.g., with the action of anti-knocks.68 Of particular interest is thediscussion on ionisation in flames, which is treated at some length,The question as to whether the ionisation is a primary or secondaryphenomenon seems to be unsolved.C. N. Hinshelwood 59 contendsthat “ i n general, chemical change is in no way dependent upon,or necessarily accompanied by anything more than a small ionisationof a secondary or accidental character.” He quotes a number ofexperiments in support of this view, and also the work of 0. W.Richardson and M. Brotherton 6o where a liquid alloy of sodiumand potassium reacting with carbonyl chloride does seem to givea real large chemical ionisation.The work of Busse has beenmentioned previo~sly.~~ There can be only one view as to thesmall amount of ionisation produced, but it is doubtful if incon-trovertible proof of its unimportance can be given. Bone quotesthe well-known work of W. 81. Thornton on the minimum sparkenergy required to ignite a given mixture, which has been continuedand greatly extended by G. I. Finch and L. G . Cowen 62 in a specialti5 2. Physik, 1928, 48, 310; A., 811.56 Wanklyn, Chem. News, 1869, 20, 271.5 8 The earlier work is excellently summerised in W. A. Bone and D. T. A.5 7 Cowper, J., 1883, 63, 153.Townend’s book, “ Flame end Combustion in Gases,” Longmans, 1927.Ann. Reports, 1927, 24, 317.6o Proc. Roy. SOC., 1927, [AJ, 115, 20; A., 1927, 713.61 Ibid., 1914, [ A ] , 90, 272; 91, 17; 1915, [ A ] , 92, 0, 381; A ., 1014, ii,6* Ibid., 1926, [ A ] , 111, 257; A,, 1926, 690. 624, 834336 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.study of the reaction when the combustion is primarily determinedby the amount of ionisation. In essence their results show thatwhen this is the case the combustion at the cathode is directlyproportional to the number of ions arriving at the cathode in agiven time. Bone and Townend conclude that “ i t is difficult toresist the conclusion that non-explosive combustion which has beentaking place in both the cathode and inter-electrode zones wasprimarily determined by the ionisation of the gaseous mediumthrough which the current passed and was independent of purelythermal factors.” Finch and Cowen point out that the heat sourceof ionisation causes cumulative ionisation, which may lead toignition and explosion at a high enough concentration.The well-known lags in some ignition phenomena may be due to thesecauses. E. Taylor Jones,g3 in a very recent review of the subject, hasexpressed the view that the best explanation of ignition by sparkingis to regard it as purely thermal.The probability of some electrical effects in the fixation ofnitrogen by the air process has also been mentioned in Bone andTownend’s book, and Bone, Townend, and Newitt believe this tobe the case. H. B. Dixon, C. Campbell, and W. E. Slater couldfind no effect at all on applying a magnetic field to explosive mix-tures, and consider that there is no ground for assuming the velocityof the explosion waves to be due to the ionising action of electrons.A. E.Malinovski 65 considered he had obtained experimentalevidence in support of the view that electrons conditioned explosionby applying a field between two electrodes ; for hexane-air mixturesthe explosion was prevented, but not for acetylene-air and hydrogen-air mixtures. In an examination of the action of anti-detonantaction G. L. Wendt and F. V. Grimm 66 were unable to repeat theseresults, as also was S. C. Lind.67 The most important work ofW. E. Garner and S. W. Saunders 68 clarified the position to someextent, Taking several published results for the number of ionspresent, they applied the Saha equation and showed that in thesecases no more ions were present than might have been expected.Lind 69 also supported this view.Since then, many studies havebeen made of ionisation in flames, but it is doubtful at the momentPhil. Mag., 1928, [vii], 60, 1090.64 Proc. Roy. Soc., 1914, [ A ] , 90, 506; A., 1914, ii, 708.65 J . Chim. physique, 1924, 21, 469; A., 1925, ii, 182.66 I d . Eng. Chem., 1924,16, 890.67 J . Physical Chem., 1924, 38, 57; A., 1924, ii, 241.8 8 Trans. Paraday Soc., 1926, 22, 281; A., 1926, 654.69 Ibid., p. 290; A,, 1926, 690; Lind and D. C. Bardwell; J . Amer. Chem.Soc., 1928, 50, 745 ; A., 455. (Compare also Marx, “ Handbuch der Radio-logie : Flammenleitung,” Leipzig, A.V.m.b.H., 1927.CATALYSIS .337if it is safe to describe it definitely either as a secondary or a primaryphenomenon. Without going deeply into the question of “ anti-knock ” action, we may quote Bone and Townend : ‘‘ Two principalhypotheses, the one ionic, the other chemical, have been advancedto explain knock, and anti-knock, but neither of them is free fromdifficulty, and as the subject is still in a very experimental andspeculative stage, the wise will ponder and scrutinise carefully suchfacts as have been proved or alleged, but will keep an open mindto their interpretation.” Lind 70 believes there is less evidence foranti-knock action being connected with ionisation phenomena thanfor flame propagation with the same cause.Of the papers which have appeared during 1928, several are ofconsiderable importance-in particular a series of papers by Semenoffand others. D.M. Newitt 71 has published a review of the largeamount of data accumulated on high-pressure explosions of mix-tures, and has published revised figures for the maximum pressureand temperature reached : these revised values are in agreementwith the extent of dissociation of steam and carbon dioxide. W. E.Garner and C. H. Johnson 72 have examined the effect of catalystson the speed of flame, the infra-red emission, and idnisation duringthe combustion of carbon monoxide and oxygen. Water vapourincreased the flame speed ten-fold and reduced the radiation toabout one-fourth. Nitrogen peroxide behaved as a feebly positivecatalyst in a dried mixture, and as a negative catalyst in an imper-fectly dried mixture.In the dry gases it was shown that there were two waves ofionisation in the explosion wave, the first being coincident with theexplosion point and the second behind it.The suggestion wasmade that the secondary emission of radiation was due to recom-bination of those ions produced behind the wave front.N. R. Dhar 73 considers that ionisation is of common occurrencein exothermal changes, and that it could usually be detected ifprecautions were taken to measure it before recombination set in.He shows how many types of changes can be explained from thepoint of view of generation of ions, when the ions and electronsthus produced are absorbed to activate the reacting substances.He makes the point that most activated gases have a very highionising potential, and that therefore thermal ionisation would bevery difficult.70 “ The Chemical Effects of a-Particles and Electrons,’’ Chemical CatalogCo., N.Y., 1928.71 Proc.Roy. Soc., 1928, [ A ] , 119, 464; A., 847.72 J , , 1928, 280; A,, 375; see also Garner and F. Roffey, Nature, 1928,73 Trans. p a r a h y soc., 1928, 24, 565; A., 1335.121, 56; A., 105338 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.A. G. White,74 in a series of papers, has examined the flamespeeds in mixtures of carbon disulphide, air, and another com-bustible substance, such as light petroleum. The law of flamespeeds breaks down when applied to mixtures. K. Yumoto 75 hasmade ZL study of the velocities of flames in carbon monoxide andhydrogen in excess of air.E.W. J.Mardles 76 published a very useful account of the action of leadtetraethyl in delaying explosion, and several other authors 77 havepublished papers on this matter. J. A. J. Bennett and Mardles 78found greater ionisation in drops than in vapour, with a correspond-ingly lower ignition temperature. They suggest that a thermionicemission occurs at the moment of ignition, followed during com-bustion by the liberation of ions from the centres of chemical changeso formed.Two papers on high-pressure explosion have recently been pub-lished from Professor Bone's laboratory. The first 79 is a continu-ation of the work on explosion of mixtures of carbon monoxide andhydrogen with oxygen.The hydrogen must exceed 0.65% to giveany effect, and then gives a sort of knock effect ; the initial additionof hydrogen is a definite catalyst, but after the first 1% there ismerely an additive acceleration ; steam accelerates the reaction insomewhat the same way, but to a less extent than an equivalentamount of hydrogen, which appears to have a greater catalyticeffect. In the second,80 data are given on the effects of moistureon the explosion of carbon monoxide and steam. The effect ofdrying is to lower the explosion range at these high pressures, andthe range can be widened by altering the temperature.H. B. Dixonsl has pointed out the complexity of the effectsof steam on carbon monoxideair mixtures. It is admitted nowthat 5-6% of steam gives the greatest rate of the explosionwave at ordinary pressures for carbon monoxide Knall-gas, whereasBone has shown that a trace of steam catalyses the reactionA number of papers on anti-detonants have appeared.74 J., 1928, 751 ; A., 697.76 Bull.I n s t . Phys. Chem. Res. Tokyo, 1928, 7 , 93; A., 1193.7 6 Nature, 1928, 121, 424.7 7 E.g., Y . Nagai and M. Furihata, J . SOC. Chem. Ind. Japan, 1927, 30, 781 ;A., 1928, 847; Y. Tanaka and Y. Nagai, ibid., 1928, 31, 20; At, 847; Y.Nagai, Proc. Imp. Acad. Tokyo, 1927, 3, 664; A., 1928, 372; P. Dumanois,Cowvpt. rend., 1928, 186, 292; A., 248; R. Duchdne, ibid., p. 220; A., 248.7s J . , 1927, 3155; A., 1928, 137.'st W. A. Bone, D. T. A. Townend, and G. A. Scott, Proc. Roy. SOC., 1928,[ A ] , 120, 646; A., 1193.W.A. Bone, D. M. Newitt, and C. M. Smith, ibid., p. 663; A., 248.Nature, 1928, 122, 806; A., 1332CATALYSIS. 339and 1% of steam gives the maximum rate. It is pointed out thatthe greater efficacy of hydrogen than of steam had been shownearlier a t Sheffield and by Dixon himself, and that in the drymixtures the difticulty was to start the flames. He has nowshown that the effect of steam and hydrogen depends entirely onthe pressure. The complexity of these reactions becomes increas-ingly revealed upon further investigation.Pressures in gaseous explosions have also been studied by G. B.Maxwell and R. V. Wheeler and by W. T. David and B. H. Thorp,82and reference may be made to a symposium on the subject ofcombustion.83 Also, Bone, Townend, and Finch contributed asummary of the present position of flame and combustion to theWorld Power Fuel Conference in London (September, 1928).Semenoff’s paper 84 contains a generalised view of the possiblemechanism of combustion, and he.shows how the cases of slow,steady combustion and explosion may both be explained by reactioncentres and branched chains.If the reaction centres are removedby the walls at the same rate as they are formed, the reaction will,of course, be uniform, but if in a given volume element suflticientheat is produced to generate a large number of reaction centres, orin fact if the chains branch to a large extent, explosion will occur.Equations are given which fit the facts with some accuracy.Assuming the Arrhenius equation, Semenoff calculates the amountof heat evolved per second, when the heat set free raises the tem-perature and increases the reaction velocity, and also the amountof heat lost to the walls of the vessel; he also considers the caseswhere explosion will occur.He shows that there must be a criticaltemperature of the walls of the flask for a given pressure of the gasmixture, which is confirmed by work of A. B. Sagulin on chlorinemonoxide and pentane-oxygen mixtures.In another case he considers the activation of molecules andchains. The reaction A + B + AB‘ can only occur thus :A’+ B --+ AB’;AB’ can lose its energy in two ways : (1) as kinetic energy toanother molecule,AB’ + A = AB + A,AB‘ + B = AB + B, or82 J., 1928, 15; A., 248; Nature, 1928, 121, 420; A,, 372.W.E. Garner, I n d . Eng. Chem., 1928, 20, 1008; D. S. Chamberlin andA. Rose, ibid., p. 1013; Chamberlin and D. R. Clarke, ibid., p. 1026; F. W.Stevens, ibid., p. 1018; R. V. Wheeler and G. B. Maxwell, ibid., p. 1041;T . E. Layng and M. A. Youker, ibid., p. 1048; Layng and R. Soukup, ibid.,p. 1062.8 p 2. Phyaik, 1928, 48, 571; A., 847340 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.or (2) by collision of the second kind,AB' + A = AB + A'.If the probability of this second process is p, and the numbers ofmolecules of A and B per unit volume are a and b respectively, themean number of molecules A' which are formed by the changeAB' --+ AB iswhich is less than unity.a = @/(a + b)If A is diatomic, however,andA'+ B -++ AB',AB' + A, --+ AB + A' + A',AB' + A, = AB + A,,AB' + B = AB + B;here a = 2@a/(a + b) and a may be greater than unity.If the concentration of AB' is c', that of A' is a', and that ofAB is c, and the total number of molecules in unit volume =a + b = n ,da'ldt = - Za'b + PZac' + no = - Za'b + ctZnc' + no (1)where 2 = the total number of all types of collision, it beingassumed that all molecular diameters are equal;anddc'ldt = Za'b - Zc'n .. . . . .w = dc/& = Zc'nwhere w is the reaction rate, and no is the number of activatedatoms of A' which are formed in unit time by thermal vibrationand black radiation.From Arrhenius's theory the number of active A' atoms per unitvolume = xo = ae-E'RT and no = xo/., where 7 is mean life of A'.Integrating equations (1) and (2) and assuming that cc is nearlyWhen t is infinite, and a < 1, w, = no/(l - a)and when a 1, w, = 00 ;and hence as long as 01 < 1 a steady reaction is possible, but in theother cases the reaction rate increases indefinitely.Since a is CATALYSIS. 341function of the pressure of oxygen, the condition M > 1 determinesthe critical range for the explosion.At a constant pressure of phosphorus vapour the critical pressuredoes not change with the temperature, and therefore in collisionsof the second kind the energy quantum transformation must bemuch greater than the mean kinetic energy of motion, and thisconstitutes the difference between reactions of this type and thereaction of the explosion type where the critical pressure increaseswith temperature according to e- E I R T .A.B. Sagulin 85 has examined the minimum pressures for explosionof mixtures of H, and C1, or Br, ; C1, and O,, C1,0, CH,, C,H,, C,H,,C,H1,, CO, and H,, and finds that in all cases the expressionlog PIT = A/T + B (compare Semenoff) is obeyed. A is a con-stant for the given reaction and independent of the bulb size;B depends on the bulb size, and has a minimum value as a ruleat 66% of either component. Some of the above reactions areregarded as purely thermal.A complete account of the “ hydroxylation” theory to accountfor preferential combustion has been given by Bone and Townend,who sum up the position by stating that if the theory is not appliedtoo rigidly it will be found to account for the facts better than anyother theory, though they consider it to be incomplete in its presentform.They do not consider an oxygenated molecule to be dis-proved, in which connexion the discussion by Egerton 86 is ofinterest. He takes the view that peroxidation is the initial causeof combustion, in much the same way as Backstrom’s mechanism.In his Royal Institution lecture he reviews the position, withspecial reference to peroxidation. W. A. Bone 87 restates thehydroxylation theory and facts supporting it, to which Egertonin principle agrees. F. Gill, E. W. J. Rlardles, and H. C. Tett 88have examined the flames or phosphorescent glow produced whenslow combustion takes place, with special reference to autocatalysisand inhibitors.They observe, inter aha, that their results supportthe view that nuclear particles are formed prior to oxidation, andthese particles, probably ionised, form the centres of chemicalchange. Their general position is that peroxidation is the generalcause of phosphorescence, autocatalysis, and detonation in a petrolengine, and that inhibitors act by removing the act.ive oxygen andenergy from these primarily formed peroxides.K. F. Bonhoeffer and H. Reicha,rdt 89 have shown from the absorp-8 5 2. plhysikal. Chem., 1928, [B], I, 275.86 Nature, 1928,121,lO; A., 137; 122,20,204. 87 Ibid., p. 204; A., 960.Trans. Faraduy Soc., 1928, 24, 574; A., 1335.2. Elektrochem., 1928, 34, 652; A., 1188342 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.tion spectra of steam containing oxygen at 1200" that free hydroxylis present.In the equation 2H,O = H, + 20H - 125,000 cals.(at 1400") the 125,000 is considered to be a minimum value, andcalculation on the Nernst equation gives results near those experi-mentally determined.E. Gaviolaw has recently published three papers on opticalexcitation by mercury. In a study of the photosensitised bandfluorescence of OH and other molecules, he has examined the pro-duction of free hydroxyl in some detail. When a few millimetresof water vapour are introduced into a tube containing excitedmercury vapour, HgH and OH bands appear. H. Senftleben and(Frl.) I. Rehrengl had concluded that the dissociation of H,O intoH and OH had to correspond to less than 4.9 volts, but Gaviolaand R.W. Wood 92 conclude that the energy must exceed this, with aprobable value of 5.20 volts. Since H, --+ 2H - 4.38 volts, thiswould give 2H,O -+ H, + 20H - 6-0 volts (about). The OHmolecule is believed to have a mean life of about 0.01 sec. underthe conditions of the experiment. About one collision in 10,000between water and metastable mercury is effective in producinghydroxyl.K. F. Bonhoeffer and F. Haber 93 have also examined the evidencefor the free hydroxyl radical and its part in flame production.Prior to Gaviola, Reis, Watson, and Meckeg4 had studied thequestion to some extent, and this earlier work is summarised.There is now no doubt that the hydroxyl radical is the emitter ofthe h 3064 band, and Haber and Bonhoeffer have fully examinedthe energy relations from both spectral data and thermochemicnlwork. They consider thatHZO = OH + H - 5 volts,which is in good agreement with the later work of Gaviola.ing Hess's law also, they obtain as a mean value,or from the spectral data of Birge and Sponer,Apply-0 + H = OH + 5-35 volts,0 + H = OH + 5.26 volts.This paper was also continued to consider the energyrelation whencarbon and hydrocarbons were present.Oo Phil.Mag., 1928, (7), 6, 1154.91 2. Physik, 1926,37,529 ; A., 1926,768.92 Phil. Mag., 1928, (7), 6, 1191 (compare S. Mrozovski, 2. P?t,yt?ik, 1928,93 2. physikd. Chem., 1928, [ A ] , 137, 263.n4 A. Reis, ibid., 1914, 88, 513; A., 1915, ii, 257; W.W. Watson, Astro-phys. J., 1924,60, 145; A., 1925, ii, 349; R. Mecke, 2. Physik, 1927,42, 390.50, 657 ; A., 1304)CATALYSIS. 343More recently still, K. Tawada and Garner,95 accepting this, haveshown how the presence of hydroxyl radical in flames will alter thetotal radiation. Measuring the total radiation from hydrogen andoxygen mixture, they showed that maximum emission occurs nearH, + 0, and not at the highest temperature, given by 2H, + 0,.Assuming that H, + 0, -+ 20H is the primary reaction, and thehydroxyl may emit a portion of its energy as chemiluminescence,this result is explained, since the life of the hydrovl is shortenedby the presence of hydrogen, and hence there should be lessradiation.Chemical Reaction by Ionisation.Reference has already been made.to the general question ofionisation in chemical change. A new edition of Lind’s mono-graph 70 contains most of the data so far available on this subject,as well as a very complete account of most of the published workon reaction by ionisation. The view is taken that clustering is thereason for more than one reaction product being formed per ionpair, and in all cases the supposed ion cluster is given. Acetylene,forming (C,H,)%, is apparently the largest cluster.The evidence for clustering is discussed by L. B. L ~ e b , ~ ~ whoshows that, whilst it is not all incontrovertible, the position is betterexplained by clusters than by the small-ion theory. The law ofBlanc, uiz.,where ka is the mobility, and c and 1 - c the concentrations, is notuniversally valid, but is useful as a criterion as to the form ofcluster; and consideration is given to the dielectric attraction ofthe molecules by the changed ion, using a fifth-power law.He concludes that in the following mixtures there is no apparentclustering : C,H, + H,; CO, + H,; 0, + CO,; C,H$ + H,.“ Statistical labile clustering ” is found in NH, + H,; NH, + air ;SO, + H,, whilst definite clustering is shown, with a negative ion,in Cl, + H,; C1, + 0,; Br, + H,; HOH or R-OH + air; with apositive ion in ether + H,; or with an ion of either sign in HC1+air; H,S; H, + I,.Besides the work above, H. A. Erikson 97 hascontinued his work on ionic mobilities by the “ air blast ” method,by which he can examine the ageing of the ion and the early stagesof cluster formation, and his results are in support of the clustera6 Nature, 1928, 122, 879.g6 PhysicaZ Rev., 1928, (2), 32, 81; A,, 932.87 Ibid., p.791; 1927, (2), 30, 343; A., 1927, 1002; 1926, (2), 28, 372;and earlier papers344 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.theory. His most recent paper deals with the mobilities of ions inmoist air, his conclusions being that water loses an electron to thefinal positive air ion, forming H,O+ of greater mobility, anddischarges the air ion.The place of ions in combustion and in some cases of surfacereaction has been or will be treated. Reactions occurring throughionisation may be appropriately mentioned here. J. E. Maisin 98has examined the oxidation of sulphur dioxide in the presence ofradon; and finds that the ratio of the number of ions disappearingto the number of ion pairs is 1.51, and hence, since sulphur trioxideis the primary product, one ion pair produces one molecule ofsulphur trioxide.R. Ruysseng9 has reasoned that the thermaldecomposition of ozone occurs in two stages : (1) the breaking ofthe molecule into negative and positive ions, proceeding withmeasurable velocity according to the number of effective molecularcollisions per second; and (2) the combination of the ions to 0,molecules being instantaneous. In support of this, he shows thatwhen the decomposition takes place in an electric field the ionisationand the decomposition are directly proportional ; and the ionisationincreases rapidly with the strength of the field.Reactions with ions as the primary causative agency have beenstudied.R. D. Rusk1 has studied the combination of hydrogenand oxygen in the low-voltage arc, and in a Geissler discharge.In the latter, he finds that at low pressures the number of watermolecules formed is less than the number of ion pairs ; but increasingthe pressure tends to bring the value up to that of Lind, i.e., 3.9pairs. He suggests that combination may be due to excitationproduced by a process secondary to ionisation. In the low-voltagearc, the reaction on an oxide-coated platinum filament was veryrapid; and whilst application of a voltage of 74 volts and thestriking of a 5 m.a. arc increased the rate of production, the differ-ence was relatively small and could not be examined in detail.A.Caress and E. K. Rideal have worked on the reactions of carbonmonoxide, and carbon monoxide and hydrogen, in the low-voltagearc. Reaction is found to begin a t the critical potentials of carbonmonoxide.Sagulin and A. Leipunsky have recently published some work onthe oxidation of mercury vapour in the presence of 5-volt electronsand show that the reaction proceeds faster when 5 volts are applied.98 Ann. SOC. Sci. Bruxelles, 1927, [B], i, 47, 172; A., 1928, 104.** Natuumuetenech. Tijds., 1928, 10, 101 ; A,, 963.1 Physical Rev., 1928, (2), 32, 287; A., 1099.4 PTOC. Roy. SOC., 1928, [ A ] , 120, 370; A,, 1198.3 2. physikd. Chem., 1928, [ B ] , 1, 362; Leipunsky, &id., p.360CATALYSIS. 345The 2537 mercury line corresponding to excitation from 1 8 to 2p2corresponds to 4-86 volt electron units, the actual value observedby Franck and Einsporn being 4.9 volts? and the reaction probablyproceeds by excitation of the mercury atoms.A. de Hemptinne 5 has examined the reduction of metallic oxidesby hydrogen in a discharge, and it is shown that lead peroxide andmercuric oxide are reduced when not directly exposed to electronicor ionic bombardment, but copper oxide or lead monoxide is not.It is held that in the tube exists un-ionised, activated hydrogen,monatomic, triatomic, or excited. Reduction a t the cathode isdue to positive ions, and a t the anode to negative ions or activehydrogen. E. G-oldsteinba has studied the synthesis of ammoniain the presence of argon in a discharge tube.Catalysis and Ionisation.The suggestion that the relation between thermionic emissionand catalysis is very intimate is now well known, and recentlythe tendency to ascribe catalytic phenomena to purely physicalcauses has increased.It has long been held that the hydrogen-oxygen reaction on a hot surface is primarily due to ionisation insome form; and of late Langmuir, Kunsman, Briner, and othershave pointed out the more general connexion.G. Owen 6 studied the pressure changes and electrical phenomenawhen mixtures of hydrogen and air reacted on a hot platinum wirea t about 300°, and ascribed the reaction to the production ofcharged nuclei by the emission from the surface, which acceleratedor caused the oxidation.He was unable to detect any changewhen fields up to 100 volts were applied, so that the existence ofthese charged nuclei was never clearly demonstrated. P. J. Kirby,'studying the reaction between hydrogen and oxygen on a heatedplatinum filament under better experimental conditions, coulddetect no appreciable reaction below a critical temperature ofca. 260". He attributed the reaction to ionisation by the emittedelectrons and subsequent reaction by the ions. Bone,8 from theresults of much work on explosions anii gaseous combustions at hotsurfaces, also suggested that the electrical emission played animportant part in surface oxidation. He pictured a mechanicalrBle for the surface, as a support where layers of electrified gaswere held and enabled to react very quickly.J.R. Thompson,g studying the same reaction, in an apparatus inZ. Physik, 1920, 2, 18.Ann. SOC. Sci. BruxelEes, 1927, 47, B, i, 143; A,, 1928, 139; Bull. Acad.TOY. BeZq., 1928, ( 5 ) , 14, 8.Phil. Mag., 1903, (6), 6, 306.6a Z. Physik, 1928, 47, 274; A., 486.Ibid., 1905, (6), 10, 467.* Rep. Brit. As~oc., 1910. v Physikal. Z., 1913, 14, 11346 ANNUAL REPORTS ON !CHE PROGRESS OF CHEMISTRY.which he could also measure very small electron currents, consideredthat the electron emission also played a very important part in therapid bulk reaction, culminating in explosion; and stated that a tthe point where explosion occurred the electron emission com-menced to rise rapidly.His results are unfortunately renderedless conclusive by his failure to measure the electron emission whilethe reaction was taking place, since the rise in emission in a vacuumat apparently the same temperature may well be fortuitous.I. Langmuir lo has shown that the relation between electronemission and catalysis is very close, and cites as an example thepoisoning of a surface as an emitter and as a catalyst, the twoprocesses running parallel to each other. R. Thomas l1 suggeststhat the process of catalysis may be a consequence only of theemission of electrons and ionisation ; he mentions many examplesof good electron emitters acting as catalysts, and makes the interest-ing suggestion that the great influence of water vapour may be dueto the formation of nuclei round any ions, in which the reactionproceeds rapidly.In a study of the combustion of hydrogen andoxygen on heated surfaces, he had observed that the reaction wasrapid on barium, calcium, or strontium oxide, and correspondedroughly to the electron currents they could produce. On alumina,a poor emitter, the rate of reaction was only about one-tenth ofthat on the other oxides. That the mechanism could not be asimple case of one emitted electron causing one pair of moleculesto react, he showed by a calculation of the saturation current,which was only of the order of of that required by that view ;but he suggests that ionisation may greatly increase these rates,and cites as an example the phenomenon of autocatalysk.The very interesting work of C.H. Kunsman l2 on the propertiesof prepared ammonia catalysts may also be mentioned : thesecatalysts of magnetite with 1% of alumina, baryta, etc., give avery large positive ion emission, some 100 times as great as theelectron emission at temperatures of the order of 600'. He con-siders that those parts of the surface which emit positive ions maybe considered to act as positive reaction centres. I n measurementsof the rate of decomposition of ammonia on prepared catalysts, heshowed that the rates could be increased four-fold by the mode ofpreparation of the catalyst, whilst a trace of promoter would causean 18-fold rise, the energy of activation remaining approximatelyconstant; so he considered that the function of the poison or10 J .Arner. Chem. SOL, 1916, 38, 2271.11 J . Soc. Chem. Ind., 1923, 42, 2 1 ~ ; A., 1923, ii, 64.1 2 J . Physical Chem., 1926,30, 626; A,, 1926, 686; Science, 1927, 66, 627;A,, 1927, 1039; J . Franklin Inat., 1927,203, 637; A,, 1927, 603CATALYSIS. 347promoter was merely to alter the value of A in the equationI< = Ae-E!RT. Promoters increase the number of atoms on whichdecomposition may take place, whilst poisoning, heat treatment, orpromoters also alter the quality of the atoms which will cause thereaction.He showed that the positive-ion work function ++ was alwayssmaller than the negative one +-, and hence the surface must beconsidered as covered with positive ions, instead of with atoms andelectrons, as 0. W.Richardson and A. F. A. Young l3 showed to bemore generally the case. There was always a single positive chargeon the ions, and no tendency to cluster was observed. Kunsmanfurther takes the view that the promoter may act by lowering 4 - 9by causing new interfaces, or by assisting the emission of a positiveor negative ion. In a more recent paper,14 he has shown that theenergies of activation for the decomposition of ammonia on heatednickel, molybdenum, and tungsten range from 26,000 to 45,000cals., and hence he discards his original idea that the energy ofactivation was a function purely of the gas and had no connexionwith the catalyst.The parallelism between catalysis and thermionic emission isfurther supported by the work of Briner l 5 and others, who haveshown that the direct oxidation of nitrogen by platinum, andoxide-coated platinum, using lime, baryta, strontia, and their mix-tures, is catalysed by these substances to a degree bearing a roughlyconstant ratio to their efficiency as electron emitters.The experi-ments are not conclusive, in that possible variations in the surfaceareas of the catalysts were not considered.L. V. Pisarshevski l6 believes the catalytic action of metals tobe due to freely-moving electrons, and states that adsorption ofgases is due to electrostatic forces binding the gas to a film of freeelectrons on the surface. Ionisation occurs either in this film or inoccluded gases; and he states that when these gases are re-evapor-ated they retain their catalytic efficiency, and can cause the thermaldecomposition of potassium chlorate at a distance of 10 or 12 cm.from the metal catalyst.The effect of ultra-violet light on metalcatalysts is shown to be due to the emission of photo-electrons.The reaction of hydrogen and oxygen on platinum foil, the catalyticthermal decomposition of potassium chlorate on metals and oxides,the inversion of cane-sugar, and the decomposition of albumosesl3 Proc. Roy. SOC., 1925, [ A ] , 107, 377; A., 1925, ii, 343.l4 J. Amer. Ohern. SOC., 1928, 60, 2100; A,, 1101.l5 E. Briner, J. Boner, 8nd A. Rothen, Helv. Chim. Acta, 1926, 9, 634;A., 1926, 916.Ukraine Chem. J., 1925, 1, Sc. Part 1, and other papers348 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.and peptoses on illuminated platinum foil, are stated to be greatlyaccelerated by illumination and the emission of photo-electrons.In general, the catalytic activity of metals and oxides is due toactivation and ionisation of adsorbed gases, which retain theiractivation on desorption.0. Schmidt 17 has examined the possi-bility of ionisation of hydrogen on a metallic catalyst, and considersit to be more likely than dissociation. Calculations on the Bohr-Kossel model and Bohr-Land6 formula showed qualitatively thationisation was possible, and was greatest on those metals havingthe smallest ionic radii, as, for example, nickel. His calculationsare in agreement with many measurements on absorption ofhydrogen.18 Further he studied the hydrogenation of ethylene oniron, cobalt, nickel, silver, gold, zinc, and lead, and obtained cata-lytic efficiencies in the inverse order of the ionic radii in most cases.It is further suggested that the organic compound in a hydrogen-ation may also be ionised by electron addition, thus permitting anelectrically neutral hydrogenation product.In a later paper an expression for the adsorption in terms of thesize of the pores is obtained, which deviates when a chemicalreaction occurs.It is stated that when ionisation of the adsorbedgas takes place and forces of attraction additional to the van derWaals terms are called into play, the force needed for the separationof the molecules of the gas is greater than the calculated values.The charging of a platinum foil diminishes its catalytic activityby destroying favourable conditions of equilibrium between positivehydrogen ions and negative ions on the surface.The work ofG. I. Finch and J. C. Stimson,lg who studied the charging of goldand silver surfaces heated in atmospheres of hydrogen, oxygen andother gases, is of interest in this connexion. The surfaces acquirea positive change in oxygen, and a negative change in a vacuumof the order or in hydrogen. They suggest that the gas isadsorbed and condensed on the surface into a layer of electricallyneutral molecules. The first stage of this process is the formationof an unstable compound, momentarily in equilibrium with neutralmolecules and the metal ; this compound then dissociates givinggas molecules which have been activated by the surface, and thelatter retains a charge.The charging up in a vacuum is explainedby the activation and emission of the metal vapour. It is suggestedthat, simultaneously with this process, the gas may be activated1 7 I;. physikal. Chem., 1926, 118, 193; A., 1926, 134; 1928, 133, 263; A.,582.18 In particukar, those of Sieverts, ibid., 1907, 60, 142; 1909, 68, 120;Naumenn and Streints, Monatsh., 1891, 12, 665; Baxter, Arner. Chenz. J.,1899, 22, 362.19 Proc. Roy. Soc., 1927, [ A ] , 116, 379; A., 1927, 1135CATALYSIS. 33.9directly. These authors find no evidence for occlusion below thesurface layers. In a more recent paper the work has been extended,and the conclusions have been confirmed; at least five types ofadsorption are distinguished, ranging from purely physical electric-ally neutral to intermediate compounds.The early experiments of P.AndersonY2O showing that hydrogen,after passing over hot platinum or palladium at about 250°, retainedits catalytic activity and could reduce copper oxide or react withsulphur at a lower temperature than in the control experiments, andsaid to be due to some activated form, have usually been consideredinconclusive owing to the possible contamination with oxygen.More careful experiments by Paneth 21 and by others 22 failed toreveal any production of active hydrogen by this means. M.P ~ l j a k o v , ~ ~ on the other hand, has observed that if hydrogen a tlow pressure is drawn over palladium, iron, or nickel at 400-800"there is no luminescence, but that if later, at a point remote fromthe metal, some oxygen is admitted, the reaction glow is produced,this effect not being shown by mixtures of oxygen and hydrogen.J. W.Broxon24 considers that there is no dependence betweenslow chemical action and ionisation in gases, and that chemicalaction has no apparent effect in increasing ionisation. The tarnishingof metals provided experimental evidence in favour of this view.A more complete study of the ionisation effects in chemicalreactions has been made by A. K. Brewer.25 In his earlier papershe shows that equal amounts of negative and positive ions are pro-duced in the surface reactions of ethyl alcohol and oxygen on goldand other surfaces. These can be measured, and the current isproportional to the applied voltages, no saturation being reached,and they are exponential with the temperature. He suggests thationisation takes place only in the surface layers, and the fieldscannot reach far enough down to remove all the ions, but only asmall fraction.It is shown that the energy required to emit anelectron is always greater than that required to cause chemicalreaction.In a review and summary of his work, he suggests a possible2o J., 1922, 121, 1152.2l F. Paneth, E. Klever, and K. Peters, 2. Elektrochem., 1927, 33, 102;A,, 1927, 429.22 A. Bach, Ber., 1925, 58 [B], 1388; A . , 1925, ii, 885; M. Scanavy-Grigorieva, 2. anorg. Chem., 1926, 159, 5 5 ; A., 1927, 119; G. A. Elliott,Trans. Faraday SOC., 1927, 23, 60; A., 1927, 187; H.M. Smallwood andH. C. Urey, J . Amer. Chem. SOC., 1928, 50, 620; A., 493.23 Naturwiss., 1927, 15, 539; 1928,16, 131; A., 1928, 459, 1308.24 Physical Rev., 1926, 27, 542 ; A., 1926, 656.25 J. Physical Chern., 1928,32, 1006; A., 968; and several earlier papers360 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.mechanism of this surface ionisation, based on the intrinsic field ofthe metal and the image field of the electron itself as it is broughtup to the surface. These ions can escape and react chemicallywhen they have sufficient kinetic energy, thus becoming thermions ;but the chance of escape depends on the distance from the surface.In this way surface catalysis becomes a special case of thermionicemission, it having been shown that there is no possibility of theelectzon emission being due solely to chemical reaction or emissionfrom the absorbed gas.Equations similar to the Richardsonthermionic equation are derived for the reaction velocity :where W , = work done by ions and image field;W , = work done by intrinsic field on ions;W3 is a measure of the effect of pressure on the emission ofW , = work required to complete the dissociation;R = rate a t which a given ion escapes into the chemicallyno = ionic concentration at the surface ;rn = mass of ion.ions ;active region ;This in general reduces to the formRate of forward reaction = dc’ldt = A1Tn’12e-b’lTwhere n‘ is the number of ions contributing to the forward reaction,and b’ includes the W factors of all the reactants.A similarexpression is obtained for the back reactionand for equilibriumThis expression is shown to be in agreement with Brewer’s ownwork, and compatible with the “ active patch ” theory, W2 beingsensitive to changes in these.In general these ideas are similar to those of (Sir) J. J. Thomson,26but the treatment is more extended.Further references to this subject are given by Hinshelw~od.~~dc” ldt = A,Tn”Pe-qITK = A T(n” n3Pe- (P - b’YTXurface Condensation.Until recently it had been tacitly assumed that the rate ofevaporation of an adsorbed film was independent of the surfaceconcentration, and that there was no lateral movement of the26 “ The Electron in Chemistry,” Chap. 4CATALY 91s.361adsorbed molecules over the surface of the adsorbing solid; but aaa result of investigations on the condensation of metal vapours,information has been obtained showing that these views must bemodified. R. W. Wood 27 showed that critical temperatures existedfor the condensation of mercury, cadmium, and iodine on glasssurfaces, and that the reflexion of atoms from the surface above thecritical temperatures followed the cosine law. M. Knudsen,28 in asimilar investigation with mercury, obtained comparable results.Langmuir 29 first discussed the possibility of forming condensationnuclei of mercury which would serve as starting points for the forma-tion of deposits at surface temperatures much above those obtainingwhen nuclei were absent.I. Estermann and M. V~lmer,~O in con-sidering the growth of a crystal by condensation of molecules fromthe vapour, suggested that when a molecule enters the field of forceat the surface of a crystal it remains there for a certain “life”time, after which it may re-evaporate, be added to the edge of thecrystal, or coalesce with others to build up a new lattice plane.In the experimental part of this work it was shown that the reflexioncoefficient cn for mercury vapour on liquid mercury was unity andindependent of the temperature, but for solid mercury it was lessthan unity. Volmer, with several other workers, has elaboratedthese i d e a ~ . ~ l A crystal should grow 1000 times faster in onedirection than another if the molecules adhered to the point on thelattice where they struck; and therefore the molecules must eitherbe able to penetrate the crystal or, more probably, are adsorbed onthe surface and can then migrate. Evidence was brought forward 32that this was probable for mercury vapour adsorbed on solidmercury and for benzophenone on glass surfaces.I n the lattercase the frictional resistance in the two-dimensional gas was foundto be about 100 times that of an aqueous solution. Microphoto-graphs gave further support to this suggestion. The nuclei form-ation in supersaturated states, and crystalline formation fromvapours, solutions, etc., were also studied.33 Estermann andVolmer 34 have shown by an ultramicroscope that the evaporatedlayer consists of a great number of small crystals.This lateral mobility over a surface-if, indeed, it exists in thecase of adsorbed vapours and gases-is evidently a factor of greatimportance in heterogeneous catalysis, for active patches or reactive37 Phil.Mag., 1916, 30, 300.28 Proc. Nut. Acad. Sci., 1917, 3, 141.ao 8. Phyeik, 1921, 1, 13.81 M. Volmer, ibid., 1922, 9, 33, 193; Phyeikal. Z., 1921, 22, 646.s* M. Volmer and G. Adhikari, 2. Physik, 1926, 35, 170; A., 1926, 349;88 M. Volmer and A. Weber, ibid., p. 277; A., 1926, 676.2a Ann. Physik, 1916, 50, 472.2. physikd. Chem., 1926, 119, 46; A,, 1926, 467352 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.interfaces may be kept supplied with reactants, not only by con-densation from the gas phase, but also by lateral migration.The mechanism of building up a new layer of condensation hasbeen investigated by several workers 3 1 9 349 359 36 and theoreticallyby J.FrenkeL3' It has been shown that the so-called criticaltemperature of condensation varies with the stream density of themetallic beam. Frenkel adopts the hypothesis that a condensedatom remains in the adsorption field for a definite life time, andduring its life at the surface it moves about in the manner of atwo-dimensiona.1 gas. If, during this motion, it collides with anotheratom, a doublet is formed which can act as a condensation nucleusfor other atoms. According to these assumptions, the life of anatom on the surface is longer in the doublet form than as a singleatom, and is also dependent on both the energy of adsorption andthe temperature of the surface, this life T being given bywhere U is the energy of adsorption.If n is the total number of adsorbed atoms on the surface perunit area, the number of isolated atoms will be nl = n(1 - no),and of paired atoms n2 = n2,, where o is the effective area of thefield.If the stream density is V, the rate of evaporation will beT" being the life of an atom in the doublet. In the stationarycondition dn/dt = 0, and this corresponds to the critical conditionfor the value of v above which condensation will take place.From Chariton and Semenoff's data for the relationship betweenthe critical stream density and the temperature of condensation ofcadmium on a mica surface, the work of evaporation of pairedatoms is 11,000 cals.per g.-mol. From Langmuir's work on theadsorption of oxygen on tungsten, a value of 170,000 cals. is found.Cockcroft has found 5,700 cals. for the evaporation of pairedcadmium atoms on copper, and about 2,000 cals. for the heat ofdissociation of the surface doublets, but the true surface forceswere probably masked by adsorbed gas films. He also obtaineddefinite proof of the surface diffusion of deposited cadmium atoms.Pbltinyi 38 has applied the I?rerikel relation q = 15T to the case of34 I. Estermann, loc. cit. ; 2. Phyeik, 1925, 33, 366; Z . Elektrochem., 1925,31, 441 ; A., 1925, ii, 1063.36 J. Chariton and N. Semenoff, 2. Physik, 1924,25, 287; A., 1924, ii, 723.313 J. D. Cockcroft, Proc. Roy. Soc., 1928, [ A ] , 119, 295; A., 945.37 Z .Physik, 1025, 33, 366.38 Chem. R m d . hlitteleuropa Balk., 1927, 4, 160; Chem. Zentr., 1928, 285;A,, 718CATALYSIS. 353catalytic acceleration of hydrogen molecules from atomic hydrogenon glass walls. He finds q, the adsorption potential, to vary from1,500 g.-cal. for wet glass to 40,000 for metals. C l a ~ s i n g , ~ ~ in asimilar manner, showed that the life of an argon molecule on aglass surface varied exponentially with the temperature, obtainingr = 0.93 x 10-11e2430/RT second.On thoriated filaments used as thermionic emitters, such surfacemobility appears evident .40Three types of adsorption of vapours by solid surfaces are nowdistinguished : (1) the unimolecular film, in many cases tenaciouslyheld, as h s t definitely suggested by Langmuir ; (2) capillary con-densation in micropores of a porous substrate, as imagined byZsigmondy and Patrick; and (3) the building up of multimolecularlayers on a plane surface, suggested by Eucken, P61&n~i,~1 andde Boer.42 The experimental evidence in favour of the first twoprocesses is reasonably convincing, but investigations on the exist-ence of multimolecular layers on plane surfaces have led to appar-ently conflicting results.The extension of the work of I. R.McHaffie and S. Lenher43 by G. H. Latham44 appears to indicatethat multimolecular Nms may be formed on rough, but not onsmooth, surfaces. The necessity for roughening the silver thimblein a dew-point apparatus, and the behaviour of a spreading oil whenpoured on water in quantities sufficient to form more than a uni-molecular layer, may be pertinent in this connexion.Despite thegreat number of adsorption isotherms proposed, it cannot be saidthat any one will be found completely satisfactory, and none iscompetent to explain the isotherms of water and alcohols onalumina, silica, silica gel, or ferric oxide. It is suggested by A.Fleischer 45 that this type of curve is generally possible for adsorp-tion of vapours, and that none of fhe above theories alone willexplain it satisfactorily ; but in many cases a combination of surfaceadsorption and capillary condensation will give a reasonableexplanation.That adsorption on surfaces might be due t o nothing more than39 Thesis, Amsterdam, 1928.40 Schottky and Rothe, “ Handbuch der Experimentalphysik,” XIII,Teil 2, Leipzig, 1928.41 F.Goldmann and M. PblAnyi, 2. physikal. Chem., 1928, 132, 321 ; A.,679. Compare also E. Huckel, “ Adsorption und Kapillarkondensation,”A.V.m.b.H., Leipzig, 1928.42 Physica, 1928, 8, 145.43 J., 1925,127,1559; 1926,1783;; compare J. C. W. Frazer, W. A4. Patrick,4p J . Amer. Chem. SOC., 1928, 50, 2987.4 5 Amer. J . Sci., 1928, 16, 247; A., 1086.and H. E. Smith, J . Physical Chem., 1927, 31, 897 ; A., 1927, 722.REP.-VOL. XSV . 354 ANNUAL REPORTS ON THE PROGRESS OF CAEMISTRY.electrostatic attraction effected by the mirror image of the per-manent dipole of the vapour in the adsorbent, was suggested byEucken. This concept of a mirror-image attraction of a permanentor induced dipole or pole of higher order has been extended byR. Lorenz and A.J a c q ~ e t , ~ ~ and H. C a s ~ e l . ~ ~ In general,the changes in potential energy effected in this way are small, withthe result that attempt,s have been made to investigate the possibleeffect of the intrinsic field as well as the mirror-image field of thesolid adsorbent on the molecules undergoing absorption.The simple treatment of J. H. de Boer 42 gives values for thedeformation of iodine adsorbed on calcium fluoride which are ofthe right order of magnitude, whilst 0. Bluh and N. Stark49 andJ. E. Lennard-Jones and (Miss) B. 81. Dent 50 have evaluated thefield outside a heteropolar crystal such as sodium chloride. Onsurfaces such as metals and metallic oxides the modifications in thedouble layer potentials effected on adsorption of various substanceshave been investigated in some detail by studies of photoelectricand thermionic emission of electrons.It is here that the intrinsicfield can be examined with the greatest certainty, and the recentwork in this particular field by Langmuir, Kingdon, Dushmann,Becker, and others, which has been ably summarised by Schottkyand R~the,~O is clearly closely akin to the problem of surface action.Molecules adsorbed from solution are believed by van Duin,51in agreement with Ihuyt and others, to be in a less favourablecondition to take part in a reaction. Working with racemic andmeso-dibromosuccinic acid and potassium iodide, the rafe is increasedby adsorbent carbon, and in this case the reacting group is turnedaway from the adsorbent into the liquid, but the velocities ofhydrolysis of some eight varied substances examined were muchreduced, as also was that of the reaction of racemic dibromosuccinicacid to form bromofumaric and hydrobromic acids.Van Duinstates that the orientation must be sufficiently favourable to over-come the primary decrease in reaction velocity caused by adsorption,if it is to increase, and there may thus be two compensatinginfluences.R. N. Pease and L. Stewart j2 have examined the relation betweenthe catalytic activity and adsorption of supported metal catalysts-iron, cobalt, nickel, and copper-on hydrogen and et.hylene.1 6 2. anorg. Chenz., 1922, 125, 47; d., 1923, ii, 13.4 7 " Theorie der Adsorption von Gasen," 1925.4 8 Phyaikal.Z., 1927, 28, 152; A., 1927, 314.49 2. Phyaik, 1927,43, 575; A., 1927, 929.50 Trans. Paraday Soe., 1928, 24, 92; A., 8.51 Rec. trau. chim., 1928, 47, 715.52 J . Amer. Chem. Soc., 1927, 49, 2783; A., 1928, 29CATALYSIS. 355F. H. G. Tammann and K. B o c ~ o v , ~ ~ and U. R.Evans 55 have examined the formation of oxide films on metalsurfaces, and the first has extended his work to evaluate the area ofthe surface oxidised, using spectrophotometric measurements of thethickness of the film, and simultaneous measurements of the electricalconductivity of the film and of the amount of oxygen absorbed. Metalfilms were deposited electrolytically on graphite, and the areas ofiron, nickel, and copper accessible to oxidation were measured inthis way.Tammann and Bochov have estimated the thicknessof a film by direct weighing, and find it higher than that given bythe colour, a discrepancy which they ascribe to absorption of airand water vapour.3’. P. Bowden and E. K. %ideal G6 have developed a novel methodfor the determination of the area of a contact catalyst, by measure-ment of the amount of hydrogen which must be deposited electro-lytically to raise the potential of the catalyst a definite amountabove that of the reversible hydrogen electrode. It is shown that1/3000 of an atomic layer raises the potential by 100 millivoltsfor a plane surface such as mercury. The ‘‘ accessible ” areas of anumber of catalysts (platinum, nickel, silver, and carbon) weredetermined in this way, and especially the effects of activation byalternate oxidation and reduction, cold working, and annealing.Constable 57 considers that the area measured in this manner wouldbe smaller than that defined by “the envelope of the unimolecularfilm of hydrogen atoms, all in contact with each other and thesurface, closely packed,” whilst Bowden 58 gives reasons for suppos-ing the ‘‘ electrolytic ” areas to be of greater significance.The Iack of uniformity of a catalyst surface, commented on byLangmuir, has given rise to the hypothesis of active patches, regard-ing which it number of different theories have been expressed.The number of surface actions which are known to be poisoned bysmall quantities of impurity is increasing rapidly (see E.B. Maxtedand A. N. Dunsby 59 on the poisoning of platinum by arsenic in theoxidation of sulphur dioxide ; also Constable 60), but no furtherevidence for the existence of patches of great chemical activity,coupled with strong adsorptive fields on a surface, has been presentedduring the last year.Constable 61 has reported on the theory of the centres of activity,63 Proc. Roy. Soc., 1928, [A], 119, 196, 202; A., 832; 11’7, 376; A., 106.64 8. unorg. Chern., 1928, 169, 42; A., 358.66 Nature, 1928, 121, 351 ; A., 375.66 PTOC. Roy. Soc., 1928, [ A ] , 120, 59, 80; A,, 1088.5 7 Nature, 1928, 122, 399; A., 1101. 6 8 Ibid., p. 647; A., 1336.69 J., 1928, 1600; A., 849.6o J . , 1927, 2995; A., 1928, 139.61 Proc. Carnb. Phil. SOC., 1928, 24, 291; A., 718.REP.-VOL. XXV. M 356 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY,and considers that the experimental facts of adsorption and catalysiscan be explained quantitatively on the basis of strong specificfields of force caused by special configurations of atoms on thecatalyst surface. Evidence from photoelectric data seems to suggestthat active patches differ but little from normal surfaces in theirintrinsic fields, and that structure, rather than field strength, is thecriterion of active patches, if indeed they exist. Thus (Miss) J.Butterworth 62 has shown that the patches of Richardson andYoung l3 can acquire the noimal work function under prolongedillumination, and R.Suhrmann's 63 observation, that the emissionfrom thin sheets of alkali metals rises with increasing potential atthe red end, bas been explained by B. Gudden 64 on the basis oflocal differences of potential of the order of 0.1 volt. Suhrmann G5points out that this is in contrast with his suggestion of surfaceionisation. The work of Bowden and Rideal cited above may beinterpreted in a similar sense.A few observations on the physical structure of the catalyticinterface are of interest. F. E. Smith 66 has examined the eficienciesof copper, nickel, their mixtures, and mixtures with alumina in thesynthesis of water in carefully controlled conditions, and correlatesthe maximum efficiency with the least shrinkage on reduction ofthe hydroxides from which the catalysts are prepared, and withsubsequent heat treatment. Smith supports Taylor's view of thecatalyst surface, and considers that the reaction probably proceedsby the interaction of hydrogen molecules with activated oxygenmolecules or atoms at points of greatest activity on the surface.E. Miiller and K.Schwabe6' measured the potentials of finelydivided palladium, platinum, rhodium, iridium, ruthenium, andosmium while formic acid was being oxidised or decomposed onthe surface of these catalysts, and found that only metals whichcould raise the pressure of adsorbed hydrogen on the surface to1 atmosphere could assist the decomposition, whilst the other metalsassist the oxidation. The potential measurements indicated thatoxidation was dependent on the activation of hydrogen,L.Duparc, P. Wenger, and C. Urfer,68 with other workers, study-ing the oxidation of ammonia on metals of the platinum group,however, consider that the efficiencies as catalysts are determinedby chemical rather than physical factors.Kunsman l4 found no increase in the catalytic activity of thoriitted62 Phil. Mag., 1928, (7), 6, 1, 352; A., 931, 1068.83 Naturwiss., 1928, 16, 336; A., 680.6 5 Ibid., p. 616; A,, 1068.6 7 2. Elektrochem., 1928, 34, 170; A., 488.6 8 Helv. Chim. Acta, 1928, 11, 337; A., 487.B4 Ibid., p. 647; A., 808.66 J . Physkul Chem., 1928, 32, 719CATALYSIS. 357tungsten over pure tungsten, molybdenum, or nickel in the thermaldecomposition of ammonia, and considers the activity to dependon the constant A in the formula K = Ae-E'RT.0.Eisenhut and E. Kaupp 69 have made an X-ray study of theiron catalysts used in the ammonia synthesis, and find maximalactivity when the lattice structure is identical with a-iron, whichis the essential constituent in all such catalysts, however prepared.have carried out experimentson the union of oxygen and hydrogen on nickel wires in a rathernovel way, examining the a'ccommodation coefficients of the wirein pure hydrogen, oxygen, and their mixtures. They conclude thatthe wire is immediately covered with oxide, and that reactiontakes place either at nuclei or at the nickel-nickel oxide interface,the latter being more probable for a thin film. B. Topley andJ. Hume 71 find that the decomposition of calcium carbonatehexahydrate is autocatalytic, and they explain this from the pointof view of an interface reaction, the formation of nuclei proceedingas the reaction progresses.Experiments with contact catalysts on other reactions, bothorganic and inorganic, are too numerous even to mention.Par-ticular attention, however, seems to have been paid to colloidalcatalysts and metallised gels. Of the former class, mention maybe made of the work of S. Liepatov on barium and copper acetatecolloids, of E. Biilmann and A. Klitt 73 on the reaction of H,(gas) =+H' on colloidal palladium, of C. Marie and P. Jacquet 7* withgelatinated electrolytic copper, of A. Korolev 75 on esterificationswith silica gel, and of F. Diaz Agnirreche,S6 who studied catalytichydrogenations on platinum oxide, which was transformed tocolloidal platinum. The use of metallised gels has been the subjectof four papers by L.E. Swearingen and L. H. Reyerson 77 and oneby V. N. Morris and Reyer~on.'~ Reactions occurring a t liquid-liquid interfaces are of interest in this connexion.796g 2. physikal. Chem., 1928, 133, 456; A., 850.70 Proc. Roy. SOC., 1927, [,4], 117, 101; A,, 1928, 27.71 Ibid., 1928, [ A ] , 120, 211; A., 1100.72 Ber., 1928, [B], 61, 45; A,, 260.2. phy&kal. Chem., 1927,130, 566; A., 1928, 28.74 Cornpt. rend., 1928, 187, 41; A., 850.7 5 J . Chem. Ind. MOSCOW, 1927, 4, 547; A., 637.7 6 Anal. Pis. Quim., 1927, 25, 411; A., 1928, 172.7 1 J . Physical Chem., 1928, 32, 113, 191; A., 252, 376; J .Amer. Chem.7 8 Proc. Indiana Chem. SOC., 1927, 36, 203; A., 1928, 488.7D See R. P. Bell, J . Physical Chem., 1928,32, 882; A., 848; G. Harker andR. K. Newman, Proc. Roy. SOC. New South Wales, 1926,60,46; A., 1928,250;W. Fraenkel, E. Wengel, and L. Cahn, 2. anorg. Chem., 1928,171,82; A.- 717.D. R. Hughes and R. C. BevanSOC., 1928, 50, 1872358 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The general problem of homogeneous catalysis in solution, andin particular that of acid and basic catalysis, has been fully dealtwith in the Discussion organised by the Faraday Society, and itwould be superfluous to report on it again here. There remain afew papers on the theoretical side which are of interest.consider the kinetics of mole-cules on a surface attached at more than one point, and calculatethe rate of desorption from the probability of one or more linkbeing broken; and the condition for singly or doubly attachedmolecules being desorbed at the same rate is also given.D. H.Bangham 81 applies an extension of Hooke’s law to the conditionin the interior of a solid when gases are adsorbed on the surface,and in the course of a very interesting paper he considers thestrains imposed by the adsorbed molecules in some detail. Heregards the sorbed molecules as distending the rigid coherentstructure of the adsorbent, which thus becomes stressed and mayeven be distorted to such an extent as to allow free gas moleculesto pass into the interior. More quantitative support for theorieson these lines might prove very valuable.Constable has endeavoured to develop a new mass-action law byintroducing the condition that reaction takes place on centres atwhich the heat of activation is smallest, and some success is attainedin those special cases where the intractable general equation canbe simplified.In another paper,8s the Reichinstein displacementprinciple for a bimolecular reaction at a catalyst surface is con-sidered from t,he point of view of inelastic collisions on the solidsurface.Frenliel and Semenoff 83 have considered the parts played bycollisions and heat radiation in activating and deactivating mole-cules, and the relation between the velocity coefficients of the twoopposing reactions is obtained. These authors show how an analysisof the kinetics of a reaction can be made more than usually valuable.In a rather different category are L. S. Kassel’s two papers 84on homogeneous gas reactions, in the first of which an expressionis derived for the velocity of a unimolecular reaction at any pressureand is shown to fit the results obtained for the decomposition ofazomethane. This theory is later extended by introducing quan-tised degrees of freedom, and the extended equation is used toaccount for the known data on nitrogen pentoxide : the agreementR. E. Burk and D. C. Gillespie80 Proc. fiat. Acad. Sci., 1928, 14, 470; A,, 847.81 Phil. Mag., 1928, (7), 5, 737; A., 599.82 Constable, Proc. Camb. Phil. SOC., 1928, 24, 56, 307; A., 262, 718.83 Z . Phy8ik, 1928, 48, 216.84 J. Phy&aE Chem., 1928,32, 226, 1066; A,, 372,960CATALYSIS . 359is good a t moderate pressures, but less satisfactory a t the lowestpressures. These two papers seem to be a definite step forward inthis most disconcerting problem. (Frl.) G. Kornfeld’s study 85 ofthe effective cross section of the gas molecule in chemical kinetics,which L. Nordheim 86 has shown to be a variable, may also begermane to this question. Kornfeld points out that in the case ofwater vapour catalysing the hydrogen-chlorine reaction, theminimum effective cross section of the water molecule is found tobe 30 times the value obtained from the kinetic theory, so thiseffect must be much larger than was supposed.R. H. Fowler 87 shows that in certain circumstances the deactiva-tion target must be very large compared with the activation target,or expressed differently, that a very slow molecule, or one withexceptionally little energy, finds it very easy to bring aboutdeactivation. L. S. Kassel,88 in a more recent paper, considersthat the collisional area cannot properly be regarded as variable,and he can arrive at no conclusion as to the mechanism of thedecomposition of nitrogen pentoxide. Fowler thinks it probablethat the radiation theory will have t o be abandoned in favour of ittheory of molecular interaction, and suggests that something in thenature of Heisenberg’s resonance theory, which may be regarded asa collision process, should be adopted.R. D. Kleeman 89 suggests a thermodynamic basis of catalysisas st result of his theoretical studies of the equation of state andthe constant of mass action. Extending his results, he shows howa dense substance in contact with reacting gases which it mayocclude can render the mass-action constant a function of thevolume and masses of the constituents; and hence a catalyst mayalter the constants of the reaction if present in more than appreciablequantities. R. Dubrisay90 has considered the same effect in aslightly different manner.The sixth Report of the Committee on Contact Catalysis, compiledby Burk,B1 contains critical reviews of most of the current theoriesin connexion with catalysis.E. K. RIDEAL.0. H. WANSBROUGH- JONES.8 5 2. phyeikal. Chem., 1927, 131, 97; A., 1928, 104.8’ ‘‘ Statistical Mechanics,” Cambridge University Press, p. 4, 1929.88 J . Amer. Chem. Soc., 1929, 51, 54.89 Phil. Mag., 1928, (7), 6, 263, 668, 1191; 8, 195; A,, 263, 470, 937, 965.O0 Trans. Paraday SOC., 1928, 24, 713; J . Chim. physique, 1928, 25, 681,91 R. E. Burk, J. Physical Chem., 1928, 32, 1601.2. Physik, 1926,36, 496; A., 1926, 654.658

ISSN:0365-6217    

DOI:10.1039/AR9282500323

出版商:RSC    

年代:1928

数据来源: RSC