摘要:

Wir konnen lhnen die nachstehenden Bucher, dieSie sich jetzt u n b e d i n g t anschaffen s o l l t e n ,zu einem um 25% ermaBigten Exportpreis iiefern.Zahlbar in lhrer Landeswahrung oder in freier Reichsmark.Schmidt, Die industrielle Chemie in ihrer Bedeutung im Weltbild und Er-innerungen an ihren Aufbau. XXXIX, 829 Seiten. RM lo.-, geb. RM 12.-Holleman, Lehrbuch der organischen Chemie. 20., umgearb. u. verm.Aufl. von F. Richter. XII, 546 Seiten. Mit 78 Fig. Geb. RM 14.-Aus AnlaB des Erscheinens dieses Werkes, und um der WirtschaftslageRechnung zu tragen, haben wir den Preis furHolleman, Lehrbuch der anorganischen Chemie. 20., verb. Aufl., bearb.von Dr. E. H. Buchner. XII, 491 S. Mit 42 Fig. u. 1 Spektraltafel. 1930von geb. RM 20.- auf geb. RM 14.- herabgesetzt.Gattermann-Wieland, Die Praxis des organischen Chemikers.24. Aufl.Mit 59 Abbild. i. Text. X111, 425 Seiten. Geb. RM 12.-Bertho-GraBmann, Biochemisches Praktikum. Mit 33 Fig. im Text u. 1Klapptafel. IX, 261 Seiten. Geb. RM 8.80Edlbacher, KurzgefaOtes Lehrbuch der physiologischen Chemie. 3.,umgearb. Aufl. IV, 286 Seiten. RM 8.50, geb. RM 10.-Kuster-Thiel, Logarithmische Rechentafeln fur Chemiker, Pharmazeuten,Mediziner und Physiker. Fur den Gebrauch im Unterrichtslaboratorium undin der Praxis berechnet und mit Erlauterungen versehen. Nach demgegenwartigen Stande der Forschung bearbeitet. 41 .-45. verb. u. verm.Aufl. Mit 1 Taf. 212 Seiten. Geb. RM 6.80Ferner empf ehlen wir Ihnen zur Anschaffiing :Meyer-Jacobson, Lehrbuch der organischen Chernie.In zwei Banden.I. Band: Allgemeiner Teil. Verbindungen der Fettreihe. Zweite Auflage.Zwei Teile. Zusammen RM 65.60, geb. 76.-II. Band: Cyclische Verbindungen. - Naturstoffe. 5 Teile (soweit er-sc h ienen). Zusammen RM 115.70, geb. (ohne V. Teil). 120.-Edlbacher, Praktikum der physiologischen Chemie. VI, 92 Seiten. 1932.Geb. RM 4.50Oppenheimer, Kleines Worterbuch der Biochemie und Pharmakologie.228 Seiten. 1920. Geb. RM 3.-Weitere chemische Literatur enthalt die Sammlung Goschen. Jeder Bandgeb. nur RM 1.62. Verzeichnis kostenlos!I - Hoppe-Seyler's Zeitschrift fur physiologische Chemie. Jahrlich erscheinen6-8 Bande zu je 6 Heften. Im September 1935 wurde der 236. Bandausgegeben. Preis: Jeder Band RM 13.50. Band 101-209, je RM 15.-.Register zu Band 151-180 RM 15,-; zu Band 181-200 RM lo.-; zuBand 201-225 RM 12.-.Wenn Sie den Wunsch haben, eine volIstand&e Serie anzuschaffen, bitten wir urnAnfrage.P r o b e h e f t k o s t e n l o s !D i e b i l l i g e n P r e i s e d i e s e r f i r S t u d i u m u n d P r a x i s 11 wichtigen L i t e r a t u r ermoglichen j e d e m dieAnschaffung. 11Walter de Gruyter & Go., Berlin W 35, Woyrschstr. 13Telegraphic Address :Telephone : ‘ I Gasthermo, Smith,Clerkenwell 2030. London .”The mark of precision and eficiency.BRITISH MADETHROUGHOUTIf you use heat-it pays to measure it accuratelyB. BLACK & SON1, Green Terrace, Rosebery Avenue,LONDON, E.C.1Thermometer Manufacturers(MERCURY IN GLASS T Y P E )Original Makers of the Improved, Gas-filled, Permanent Thermometers forLaboratory and Industrial Processes.Standard Thermometers of the highestaccuracy covering over a range fromminus 200 to plus 520° C.The black filling-in etchings will resistall solvents with the exception of thosethat attack the glass itself.The National Physical LaboratoryCertificates supplied, with any type.Of all the principal Scientifk Instrument and LaboratoryApparatus Manufactrrrers.1SCIENTIFIC BOOKSH.KO LEWIS & Coo Ltd.A very large selectionof new and standard worksin every branch of Sciencealways available.The Department for ScientificBooks, English and Foreign, is onthe first floor. (Passenger Lift)Orders and Inquiries by Postpromptly attended to.Undergrqund : Euston Square, WarrenStreet.Buses: Euston Road and Totten-ham Court Road.Corner of Gower Street and GowerPlace adjoining University College.SCIENTIFIC LENDING LIBRARYAnnual Subscription, Town or Cotintry, from One GuineaBooks may be retained as long as required or exchanged daily.The LIBRARY is useful to SOCIETIES and INSTITUTIONS, andto those engaged on SPECIAL RESEARCH WORK, etc. TheLibrarv includes all Recent and Standard Works in all branches ofMedical and General Science. Every work is the latest edition.Detailed Prospectus on Application.READING AND WRITING ROOM (first floor) open daily.NEW BOOKS AND NEW EDITIONS are added to the Library andare available to Subscribers IMMEDIATELY ON PUBLICATION.BI-MONTHLY LIST OF NEW BOOKS AND NEW EDITIONSis issued free to all Subscribers and Bookbuyers regularly.H. KO LEWIS & Coo Ltd.PUBLISHERS AND BOOKSELLERSNotebooks, Record Cards, Filing Cabinets, etc.STATIONERY DEPARTMENT : Scientific and General.SECOND-HAND BOOKS : 140 Gower Sfreef.Loose-LeafLarge and varied sfock.Books wanted advertised for and reported.(Telephone : Museum 4031)136 GOWER STREET, LONDON, W.C.1Telegrams : Telephone :' PUBLICAVIT, WESTCENT, LONDON.' MUSEUM 7756 (3 lines)....11The DERBYSHIRE SILICA FIREBRICK Co., Ltd.FRIDEN - HARTINGTON - Nr. BUXTONManufacturers of theHIGHEST GRADE REFRACTORIESFOR ALL INDUSTRIESPARTICULARLY SUITABLE FORWATER TUBE BOILERSPART OF WORKS SHEWING SOME OF THE PRESSES.Also Manufacturers of the‘‘ DOME ”* BRAND INSULATING BRICKSUse these and Sam FuelTelegrams :“ Silica” Friden, Hartington.Telephone :Hartington 30I N S U L I NI T S P R O D U C T I O N , P U R I F I C A T I O NA N D R C T I 0 N P H Y S I 0 I, 0 G I CAI.byDOUGLAS VV.HILLB.Sc.(Bris.), Ph.D.(L,iv.), Lecturer in Chemistry, University College, Exeter ;Special Lecturer in Organic Chemistry, University of RristolandFREDERICK 0. HOWITThl.Sc., F.I.C., Ph.D.(London)Professor E. C. DODDS in his Foreword writes: “In thesepages will be found a very accurate review of the progress L I ~ to thepresent time.”C O N T E N T SI. DIABETES MELITUS-2. PRELIMINARY ATTEMPTS TO ISOLATETHE PANCREATIC HORMONE-3. THE PREPARATION OFPHYSICAL AND CHEMICAL PROPERTIES OF INSULIN (includingthe action of enzymes)-6.PHYSIOLOGICAL PROPERTIES OFINSULIN-4. PURIFICATION OF INSULIN PREPARATIONS--5.INSULIN-7. MODE OF ACTION OF INSULIN-8. STANDARD-ISATION OF INSULIN PREPARATIONS-9. POSSIBLE SUBSTI-TUTES FOR INSULIN.240 Pages, Demy OctavoPhotomicrographs, Tables, Indexes, exhaustiveBibliography, 1216HUTCHINSON’S SCIENTIFICAND TECHNICAL PUBLICATIONSPaternoster House, E.C. 4_ _ _ _ ~ ___________THE POLYTECHNIC, REGENT ST., W . lDEPARTMENT OF CHEMISTRYHead of Department : H. LAMBOURNE, M.A., M.Sc., F.I.C.Day Courses:B.Sc. Degree Special and General (External), London University.Associateship of the lnstitute of Chemistry (A4.1.C.) Diploma.Pre -Medical Course in Chemistry, Biology, Physics.Evening Courses :( a ) B.Sc.Degree Special and General (External), A.I.C., Inter-mediate Science, Pre-Medical Course in Chemistry and Physics,National Certificates in Chemistry.( h ) Applied Courses in Gas Engineering and lllanufacture ; Pig-nients, Varnishes, l’aintq, Enamels and Cellulose Finishes ; Oils,Fats and Waxes. 1I I Full prospectus on application to the Director 01 Education.APPOINTIWENTS BOARDof theIMPERIAL COLLEGE OF SCIENCE & TECHNOLOGYSouth Kensington, S.W. 7IncZGdzng :CITY AND GCTILDS COITFCE.ROYAT, COILEGE OF SCIENCE, ROYAL SCHOOL OF MINES,EMPLOYERS rcquiring graduates trained in scientific or technical studiesarc asked to make use of the services of the Board.In the Chemical Department students are trained in Inorganic, Organicand Physical Chemistry, with special attention to analytical methods,and graduates who have done postgraduate research work in one of thesebranches, and in Agricultural Chemistry, are available.In the Department of Chemical Technology, the post-graduate coursesinclude instruction and research in the Chemistry of Fuel and Combustion,Reactions under High Pressure Catalysis, Chemical Engineering, etc.The services of the Board are free, and the Registrar will be pleased todeal with any enquiry.Employers can be put into direct communicationwith the Professor respecting any student considered for an appointment,so that first-hand information as regards suitalsility for the work proposedcan be obtained.Enquiries should in the first instance be addressed to the Registrar,Imperial College Appointments Board, Prince Consort Road, S.W. 7RAPID DRYINGOF SOLIDS, CRYSTALS A NGRANULAR MATERIALSThe quickest and most effective methodof mechanically drying crystalline andgranular materials is by '' Watson-Laidlaw '' centrifugal machines.They are etticient i n operation andreliable to a degreeWATSON, LAIDLAW & Co., Ltd.,S o u t h Telephone 1700. : 98, LAIDLAW STREET, s 6 F ~ ~ ~ ~ ~ ~ & . , .GLASGOW, C.5viQUEEN MARYCOLLEGEOFARTS. SCIENCEENGINEERING(University of London)Principal :Maj.-General Sir Frederick Maurice,K.C.M.G.,C.B., LL,D., D.Lit.Provision is made for ResearchWork for Students preparingfor M.Sc., Ph.D. and D.Sc.Degrees in Chemistry.Theresearch laboratories are wellequipped with apparatus foradvanced work in Chemistry.Bees from B22 10s. a year.Halls of Residence for MenStudents and for WomenStudents.__ __-- ~~P v o s p e c k Free 0% ap$dicmtiopzto the REGISTRAR-QUEEN MARY COLLEGE, E.I.G U R R ’ SSTAINS ANDREAGENTS FORMICROSCOPY.TJsed and approved in theprincipal laboratories.Stains in Powder, Solutionor Tablet Form :Mounting Media, BacteriologicalSugars, Immersion Oils, Hydrogenion Indicators, Filtered ParaffinWax, Microscopical Sundries, g ~ c .Price I-ist and Literature ojtapplicatio9a.GEORGE T. GURR136 NEW KING’S ROADLONDON, S.W.6Phone : Telegrams :I’UTNEY 1463. GURR, PUTNEY 1463.Telegrams: BELLAMY, PHONE, LONDONTelephone : EAST I892JOHNBELLAMYLTD.43 BYNG STREET,MILLWALL, E. 14Makers of TANKS, MIXERS,AUTOCLAVES, etc., in Mildand Stainless Steel to suitt h e special requirements oft h e CHEMICAL MANU-FACTURERSSPECIAL ATTENTION TOINDIVIDUAL DESIGNSviiORGANIC CHEMISTRYB y JOHN READ, Pfi.D., M.A., Sc.D., F.R.S.New and Revised EditionThe latest edition of this well known work includes two newchapters on Hormones and V i t a v ~ i n s and the Electronic Theoryof Valency ifz Organic Chemistry and has generally been broughtabreast of modern advances in the theory and practice of organicchemistry. (‘ Prof.Read’s book is well known as one of the bestof its kind, not merely for the mastery of his subject that theauthor displays, but especially for the cultured elegance of hisstyle.”-Journal of Education.xiv + 704 pages, 87 figures: price 12s.6d. net.7 “AN INTRODUCTION TO ORGANIC CHEMISTRY,” by J o h ~ Rend.viii f 366 pages, 50 illustrations ; price 6s. 6 d .VOLUMETRIC ANALYSISB y G. FOWLES, M.Sc., A.I.C.‘< . . . can be strongly recommended, and for the amount ofinformation contained in it, is the cheapest modern manualof volumetric analysis.”-School Science Review.2nd Edition I. xii + 204 pages : price 6s.G. BELL & SONS, LTD., YORK HOUSE, PORTUGAL ST., W.C.2We are manufacturers of all kinds ofFACT0 RY EQ U I PM E NTL I Q U I D F I L L I N G M A C H I N E SApproved by Board of Trade Standards Department f o r Barrels,RUMBLING & CHAINING MACHINESFor the interior o f Barrels and Drums.AIR PRESSURE TESTING MACHINESFor Drums and Cans.WASHING & CLEANING MACHINESW i t h Patent Self-Rotating Nozzles for Barrels, Drums and Cans.C O A T I N G & P A I N T I N G M A C H I N E SFor the interior of Barrels and Drums.VACUUM & PRESSURE RELIEF VALVESFor large Storage Tanks.SAFETY ELECTRIC HAND LAMPSW i t h Steel Alkaline, o r Lead Jelly Acid Accumulators.SAFETY ELECTRIC HAND TORCHESW i t h 3-Cell dry Battery and Spotlight Bulb.The above are approved by the Mines Department in explosive atmospheresDrums and Cans.Special Machines built to customers’ own requirementsIllustrations and particulars of the above machines and equipment sent on requestDOWNS ENGINEERING WORKS LTD.SOUTHFIELD ROAD, ACTON, LONDON, W.4Telephone: CHISWICK 2840/1iPURIFICATIONOFWATERFOR ALL PURPOSESBOILER FEEDPROCESS WORKTEXT1 LE PU RPOSESTOWN SUPPLY, Etc.IS THE SPECIALITY OFE N N I C OT'WATER SOFTENERWOLVERHAMPTONCQ., LTD.Established 40 YearsPLACE YOUR WATER PROBLEMSBEFORE US AND AVAIL YOUR-SELF OF OURUnrivalled ExperienceX To face title page

ISSN:0365-6217    

DOI:10.1039/AR93532FP001

出版商:RSC    

年代:1935

数据来源: RSC

摘要:

ANNUAL REPORTSON THEPROGRESS OF CHEMISTRY.RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.DURMG the year, very rapid progress has been made in the study ofartificial disintegration. The transformations among the lighterelements have been in many cases so inter-related that one canspeak of nuclear reactions and a nuclear chemistry. The energyrelations have led to a new scale of nuclear mass, and the detectionand measurement of excited levels in these atoms are the beginningof a stage in the ‘( nuclear quantum physics ” initiated by the relationof a- and 7-rays in former years. The use of neutrons as bombardingparticles and the development of the (( slow neutron ” process haveled to wide developments in transmutation among the heavierelements. Some progress has been made in the study of the p-raytransformation and of the penetrating radiation.1.ISOTOPIC CONSTITUTION OF THE ELEMENTS.In this field, work has continued with the mass spectrographand by spectroscopic methods. The technique of the formerconsists largely in obtaining ions from recalcitrant elements, andA. J. Dempster has introduced for this purpose a high-frequencyspark between solid metal electrodes in a high vacuum. Thissource yields abundant ions from many elements, including Pt,Au, W, and Sn. Platinum examined by this method gave isotopesat 192, 194, 195, 196, 198, the lightest being faint and 198 not sostrong as the other three; palladium gave isotopes at 102, 104,105,106, 108, 110. Gold gave no trace of Au 199 and it is suggestedthat its accepted atomic weight is too high.Iridium gave 191 and193, the latter being the more ab~ndant.~ Uranium gave oneisotope at 235 with intensity < 1% of that due to U238, and it is1 Nature, 1935,135, 542 ; A., 677.2 A. J. Dempster, ibid., p. 993; A., 909.3 Idem, ibid., 136, 909; cf. B. Venkatesachar and L. Sibaiya, ibid., p. 437 ;A , , 129516 RADIOACTIVITY AND SUB- ATOMIC PHENOMENA.suggested that this substance is the parent of the actinium ~ e r i e s . ~Further evidence on the actinium probleni is obtaiiied from achemical determination of the atomic weight of protoactiniumby A. von G r ~ s s e . ~ F. W. Aston has published new mass-spectrograph results on Hf, Thy Rh, Ti, Zr, Cay Ga, Ag, Ni, Cd, Fe,In, and the mass-spectrograph has also been used to obtain valuesfor the abundance ratio of isotopes of Li, K, and Rb.'X'ectroscopic Methods.-The study of hyperfine structure ofspectral lines which show an isotope splitting and the investigationof band spectra now provide a more or less definite contributionto our knowledge of isotopes. For instance, in platinum the ratioof the abundance of Ptlg2, Ptlg4, Ptlg5, Ptlg6 is given as - : 5 : 8 : 8 byB.Fuchs and H. Kopfermann and as 2 : 10 : 13 : 16 by B. Ven-katesachar and L. Sibaiya,Y both sets of workers using photometryof the hyperfine structure of PtI lines, while band spectra have beenused to investigate the isotopes of cadmium, zinc (hydride bands),lOand indium (iodide bands). l1Some additions have been made to the determinations of nuclearmechanical and magnetic moments by the methods discussed inthe Report for 1934.The new determinations include holmium,12hafnium,13 silver,l4 lanthanum,15 and potassium.16 The onlyimportant technical advance represented is a spectroscopic one,oix., the use of absorption-spectrum lines taken with an atomicbeam to avoid Doppler effect. Regularities in the distribution ofnuclear mechanical moments among atoms of odd and even atomicnumbers have been noticed by S. To1ansky.l'Among the lighter elements, the study of the nuclear transmut-A. J. Dempster, Nature, 1935, 135, 180; A . , 1048; A. von Grosse, J .J . Amer. C'hem. Soc., 1934, 56, 2501 ; see also these Reports, p, 146, andProc. Roy. SOC., 1935, [A], 149, 396; A., 802.Physical Chenz., 1934, 38, 487; A., 1934, 578.review by G.Elsen, Ghern. 'CZ;'eelcblad, 1935, 32, 343; A . , 910.' H. Rondy, G. Johannsen, and I<. Popper, 2. Physik, 1935, 95, 46; A . ,909; A. K. Brewer arid P. D. Kueck, Physical Bev., 1934, [ii], 46, 894; -4 .,1935, 140.ii-aturwiss., 1935, 23, 372; A., 909.Proc. Indian Acad. Sci., 1935, 2, A, 101; A., 1185.10 G. Stenvinkel and E. Svensson, Nature, 1935, 135, 955; A., 802.l1 M. Wehrli, Helv. Physica Acta, 1934,7,611; Chem. Zentr., 1934, ii, 2960 ;A . , 1935, 558; cf. A., 1934, 1286.H. Schuler and T. Schmidt, Naturwiss., 1935, 23, 69; A . , 424.la E. Rasmussen, ibid.; A., 424.H. Hill, Physical Rev., 1935, [ii], 48, 233; A., 1183.l5 ill. F. Crawford and N. S. Grace, ibid., 47, 536; A., 676.l G D.A. Jackson and H. Kuhn, Proc. Roy. Soc., 1935, [A], 148, 335; A.,l7 Nature, 198.5, 135, 620; A . , 676.555BRADDICK. 17atioiis which take place when these are bombarded with protons ordeuterons has led to an interesting revision of nuclear masses.The necessity for revision was pointed out independently byH. A. Bethel8 and by M. L. E. Oliphant, A. E. Kempton, and(Lord) R~therford.1~ In nuclear reactions there is strong evidencethat the law of conservation holds if mass and energy be regardedas equivalent. The energies involved in the transmutation of theH, He, and Li nuclei among themselves may be beautifully explainedon this basis,20 the masses for the nuclei being taken from themass-spectrograph work of Aston and of Bainbridge.If we regardthe nucleus Be9 as made up of two a-particles and a neutron, themass assigned by K. T. Bainbridge 21 (9.0155; 0l6 = 16.000)exceeds that of the components (8.0043 22 + 1.0080 23) by the equi-valent of about 3 M.E.V.* and the Be9 nucleus should therefore beunstable.No spontaneous disintegration had, however, been found bycareful experiment^.^^ Further, the energy of the a-particlesobtained when Be is bombarded with protonsis much less than that calculated from the mass data of Bainbridgeand of Aston.19 A separate experiment showed that the excessenergy was not radiated as a 7-ray. Similar difficulties arise inconnexion with the a-particles obtained by bombarding berylliumwith deuterons,Be9 + 1H2+ ,Li7 + ,He4and in the case of boron bombarded with protons.25Oliphant, Kempton, and Rutherford 19 point out that in the mass-spectrograph determinations the masses of HI, H2, Li6, and Li7were determined by comparison with He4, whereas those of Be9, B1*,and Bll were determined by comparison with 016 with differencesdetermined with reference to HI.A small error in the mass ratioHe4/O16 would give it cumulative error in the masses of the otherelements. By assuming a, small error in this ratio and applying aPhysical Rev., 1935, [GI, 47, 633.l9 Proc. Roy. Soc., 1935, [ A ] , 150, 241; A , , 910.2o Idem, ibid., 149, 406; A., 803.21 Physicdl Rev., 1933, [GI, 43, 367.22 F. W. Aston, Proc. Roy. SOC., 1927, [ A ] , 115, 487.23 J. Chadwick and M. Goldhaber, Nature, 1934, 134, 237.24 See, e.g., E.Friedlander, Compt. rend., 1935, 201, 337; A . , 1185; R. D.Evans and M. C. Henderson, Physical Rev., 1933, [ii], 44, 59; A., 1935, 141.25 D. M. Gans, W. D. Harkins, and H. W. Newson, ibid., p. 310; A., 1935,141 ; F. Kirchner, Physikal. Z., 1933, 34, 897 ; A., 1934, 128.* M.E.V. signifies one million electron-volts here and throughout thisReport18 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.corresponding correction to the mass-spectrograph data, it ispossible to obtain a set of masses which agree much better withtransmutation data. F. Kirchner and H. Neuert 26 had previouslysuggested a revision of the mass of Be9 to fit in with their transmut-ation data. Bethe 1* pointed out that the excited CI2 nucleuswith 4-8 M.E.V.extra energy was still stable against disintegrationinto three or-particles, while the masses given by Aston wouldnecessitate instability a t a much lower excitation energy. Hedrew up a new scheme of masses for the elements up to ol', andsuggested a revision of the He4/O16 ratio. The new atomic massesare given in Table I. F. W. Aston 27 has redetermined the massesof some of the light nuclei and has found values in better accordwith the masses deduced from energy changes.TABLE I .Revised Nuclear Masses based on Transmutation Data.Bethe. 18 Oliphant et al. l9 Aston, etc.lH1 1.0081 1.0081 1.0081 * onl ..................... 1.0085 1.0083lH2 ..................... 2.0142 2.0142 2.0148 *1H3 ..................... 3.0161 3.0161 3.01512Hp4 ..................4.0034 4.0034 4.0041 *,L16 ..................... 6.0161 6-0163 6.0175,Li7 ..................... 7.0169 7.0170 7-0176,Bes .................. 9-0135 9.0138 9.01646B10 ..................... 10.0146 10.0143 10.01355B11 .................. 11.0111 11.0110 11.0121&I2 ..................... 12.0037 12.0027 12.0048,C13 ..................... 13.0069 13.0061,N14 .................. 14.0076 14.0042,N15 .................. 15.0053 15,00328 0 1 6 .................. 16*0000 16.0000 16.0000.....................8 0 1 7 .................. 17.0040Values marked * are from Aston.27The study of artificial disintegrations has led to new precise valuesof a few other nuclear masses.28 C. D. Ellis and W. J. Henderson 29have shown that the upper limit of the pray or positron spectrummay be used to calculate the energy differences between the initialand final nuclei in a p-transition, and this reveals the possibility ofdetermining a large number of nuclear masses, since the greatmajority of the artificial radioactive transformations %re of thistype.It should be pointed out that the exact nuclear masses arequantities of great importance, since they have a very directconnexion with the binding forces in the nucleus.2 6 Physikal. Z., 1935, 36, 54; A., 277.a? Nature, 1935, 135, 541 ; A., 677.28 E. 0. Lawrence, Phy8icaZ Rev., 1935, [GI, 47, 17; A., 277.29 Proc. Roy. SOC., 1935, [ A ] , 152, 714BRADDICK. 19The mass of the neutron which appears in this table rests uponseveral independent experimental results.30 The transformationwith the new Aston masses 27 for H1 and H2 and the energy of the7-ray determined by Fleischmann 31 gives a value 1.0083.P. I. Deeand C. W. Gilbert’s investigation 32 of the reaction 1H2 + 1H2 4,He3 + on1 enabled them to deduce the mass 1.0080 & 0.0004.The neutron may therefore give a proton and an electron by anexothermic reactionon1 = lH1 + e + 0.2 M.E.V.332. NUCLEAR TR~SMUTATION.Work on the production of new atomic species by bombardmentof elements with a-particles, protons, deuterons, and neutronshas continued during the year, so there is now a regular ‘‘ nuclearchemistry.” Many of the nuclei obtained are radioactive withhalf-life periods varying from 0.02 sec. to several months. Inseveral cases, a given new nucleus can be obtained by several routes,and in many cases the new elements have been identified by chemicalmethods, e.g., precipitation with appropriate reagents after theaddition of an isotopic or homologous ion.Following Fleischmann and Bothe,31 we shall denote, e.g., thereaction ,W4 + ,He4 -+ 8017 + lH1 as one of type (a; p).Theexpulsion of neutrons by a-particles then becomes a reaction oftype (a; n). Protons may give reactions of types ( p ; a), ( p ; n), or( p ; -) (capture). Deuterons give ( d ; a), ( d ; n), and, rather fre-quently, ( d ; p ) , while neutrons give ( m ; a), (n; p ) , and (n; -).cc-ParticZes.-No new ( a ; p ) reactions giving rise t o stable nucleihave been discovered, but several processes of this type, givingradioactive nuclei (Curie-Joliot type) have been reported.Siliconbombarded with a-rays gives a product of half-life 17-18 days,which is probably 15P32 and gives electrons and not positrons ondisintegration. The half-life and the absorption coefficient of thep-rays agree with those of 15P32 obtained by bombarding 16Si32 withneutron^.^^^ 35 Magnesium bombarded with a-particles gives30 Cf. ref. (23).31 2. Physik, in the press; see also R. Fleischmann and W. Bothe, Ergeb.exakt. Naturwiss., 1935, 14, 1.32 Proc. Roy. Xoc., 1935, [A], 149, 200; A,, 678.33 G. Wentzel, Naturwiss., 1935, 23, 35; A., 278.34 H. Fahlenbrach, ibid., p. 288; A., 803.35 Idem, 2. Physik, 1935, 96, 503; A., 80320 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.several active elements, the most probable process being 349 36* 3712Mg25 + ,He4+ 13A128 + lH113A128-+ 14Si2B + e- (7 == 2.1 m.)but the following reactions probably also take place :,,Mg26 + 2He4---+ 13A129 + lH113A129 + 14Si29 + e-12Mga + 2He4 + 14Si27 + on114Si27 ---+ 13A127 + e+0.R. Xri~ch,~* on bombarding sodium fluoride or lithium fluoridewith cc-particles, found an activity which he ascribed to Na22formed by an ( a ; p ) process. The half life was > 6 months, and themean energy of the positrons was 0.2 M.E.V. Calcium gave apositron-emitting element, probably Sc43, with a half period ofabout 44 hours. This is the heaviest nucleus for which there isconvincing evidence of disintegration of this type.A few furtherinvestigations have been made on previously known reactions.New determinations 39 of the halving period of radio-nitrogen,7N13, give 11.0 and 10.73 minutes, which is identical with thatof 7N13 obtained from &P2 by ( p ; -) and ( d ; n) processes.Several new processes of the type ( a ; n) have been discovered.Silicon and phosphorus were found to give neutrons when bom-barded with a-particles,40 ahd 0. Haxe141 finds that nitrogengives under fast a-bombardment a radioactive nucleus of half life1.2 minutes in addition to the long-known (cc ; p ) transformationinto stable O17. The new nucleus is probably PI7 produced by thereaction 7N14 + 2He4 --+ + on1 (cf. p. 23). K. Schnetzler 42has interpreted his results on the excitation function (see below) oflithium as indicating an excitation process without capture of thea-particle or emission of charged particles.P. Save143 has foundevidence of a similar process in Li, N, Al, IF. In the (a ; p ) process5B10 + ,He4-+ &Y3 + lH1the C13 nucleus may often be left in an excited state which emitsa 7-ray, the proton carrying away less than the full energy of thetransformation. This interpretation has been confirmed by a36 C. D. Ellis and W. Henderson, Nature, 1935, 136, 755.37 A. Eckhardt, Naturwiss., 1935, 23, 527; A., 1049.38 Nature, 1935, 136, 220; A., 1186.39 C. D. Ellis and W. Henderson, ibid., 135, 429 ; A., 559 ; H. Fahlenbrach,2. Physik, 1934, 94, 607.40 E. Amaldi, 0. d'Agostino, E. Fermi, B. Pontecorvo, F. Rasetti, andE.Segr6, Ric. Sci., 1935, 0, [i], 11/12.dl Z. Physik, 1935, 93, 400; A., 426. 42 Ibid., 95, 302; A., 1049.43 Ann. Physique, 1935, [xi], 4, 88; A . , 1049BRADDICK. 21coincidence counter method by W. Bothe and H. J. von B a e ~ e r . ~ ~A group of full-energy protons is also emitted, and these show nosimultaneity with y-ray emission.Protons.-Considerable data have been accumulated on thedetails of the disintegration of lithium, beryllium, boron, carbon, andfluorine by artificially accelerated protons ; carbon alone gives anunstable product-nucleus, apparently by the simple capture reaction6Cl2 lH1-+ 7W3 hv,N13 + 6C13 + e+ 45946The radioactive substance behaved physically like nitrogen 45 andgave a positron emission with an energy distribution extending upto about 1.1 M.E.V., which is in reasonable agreement with thevalues for N13 obtained by bombarding boron with a-particles (foridentity of periods, see ref.39). The ‘‘ capture y ” radiation wasdetected : 46 it was ( 6 hard ” but was too weak to be examined indetail. The y-rays produced in the bombardment of boron4‘ andlithium 48 by protons have been examined by measuring the energyof recoil electrons in a cloud chamber. The energies in the case ofboron go up to about 14.5 M.E.V. and are ascribed to the reactionBll + H1+ C12. The lower energies present may be due to analternative process Bll + HI+ 3He4 or to a step-wise relaxationof a C12 nucleus excited to 14.5 M.E.V. The possible existenceof a 14.5-M.E.V. excited level in C12 raises interesting theoreticaldifficulties. I n the case of lithium the capture y radiation is foundto show a complicated structure of discrete lines with energies upho 16 M.E.V.The reaction is supposed 49 to be Li7 + H1 + He4 + He4 and the y-rays are due to excitation of the a-particles, whichmust have a series of energy levels between 0 and 16 M.E.V.50The transmutation functions of CI and p processes, i.e., thevariation of the probability of a transmutation with the energy ofthe bombarding particles, have been the object of special study.The bombarding particle may get inside the nucleus by passingover a potential barrier representing the repulsive forces of the44 Nach. Ges. Wiss. Qbttingen., 1935, 1, 195; von Baeyer, 2.Physik, 1935,85, 417.45 J. D. Cockcroft, C. W. Gilbert, and E. T. S. Walton, Proc. Roy. SOC.,1935, [ A ] , 148,225; A., 276.4 6 L. R. Hafstad and M. A. Tuve, Physical Rev., 1935, [ii], 48, 306; H.Neuert, Physikal. Z., 1935, 36, 629; A., 1297.47 H. R. Crane, L. A. Delsasso, W. A. Fowler, and C. C. Lauritsen, PhysicalRev., 1935, [ii], 48, 102.48 Idem, ibid., p. 125; A., 1186.49 M. L. Oliphant, E. S. Shire, and B. M. Crowther, Proc. Roy. SOC., 1934,60 C. C. Lrturitsen and H. R. Crane, PhysicaZ Rev., 1934, [ii], 46, 637, 1109.[A], 146, 922; A., 1936, 722 RADIOACTIVITY AND SUB -ATOMIC PHENOMENA.nucleus or by a ‘‘ resonance ’’ process in which a particle with adefinite special amount of energy is transmitted through the barrier.In the former case the transmission is calculated by Gamow’s theory,which gives a monotonic, approximately exponential increase withenergy of the incident particle; in the case of resonance, there are’peaks in the transmission curve and therefore in tho transmutation.function.The resizlts available up to October, 1934, have been.used in a paper by E. C. BollardJsl in which the values deduced for.the height of the potential barriers are tabulated, together withresonance levels. The barrier heights and resonance levels lie on asmooth curve when plotted against atomic number. The barrierheight is not the same for a-particles and for protons. Resonanceoccurs both for a-particles and for proton transmutations; it isparticularly well marked for proton-capture processes of the type&12 + lH1--+ ,W3 + y.This reaction shows two sharp reson-ances at 480 and 400 kv. The 7-ray emission from lithium bom-barded by protons shows resonance at 450 and 860 lw.? but theserays from beryllium similarly bombarded do not appear to showresonance.52 A theoretical analysis has been made by G . Breitand F. L. Yost,53 who find that the simple model of the nucleus as apotential well surrounded by a region of inverse-square field must bemodified to account for the experimentally observed probability ofcapture in the case of carbon.Deuterons.-The use of the H2 nucleus (deuteron) as a bom-barding particle has led to very interesting results.The transmutations of nitrogen ,El4 + 1H2 --+ &12 + ,Ho4[(d ; a) process] and 7N14 + 1 H 2 t + lH1 [(d ; p ) process] havebeen studied by E.0. Lawrence, E. McMillan, and M. C. Hender~on.~~The existence of excited levels in the C12 and W5 nuclei gives riseto a complicated set of ranges among the products, since differentamounts of energy may be taken up by the nuclei and radiated asy-rays. The y-rays emitted in these processes have been studied bythe cloud-chamber recoil method,65 and a set of y-ray lines observed.These data may also be compared with the energies of the 7-raysobserved in the reactions 561 53B1l + H2-+ C12 + ,,nland,Be9 + ,He4+ &12 +51 Physical Rev., 1936, 47, 611; A,, 804.51 L. R, Hafstad and M. A. Tuve, ibid., p. 506; 48, 306; A., 1297.53 Ibid., p. 203; A., 1186.55 H. R. Crane, L.A. DeIsiZsso, W. A. Fowler, and C. C. Lcturitsen, ibid.,56 Idem, ibid., 1934, [ii], 46, 1110.5 7 H. Becker and W. Bothc, 2. Physik, 1932, 76, 421.54 Ibid., 47, 273; A., 659.4,100BRADDIOK. 23There is therefore good evidence of the existence of series of excitedstates in the light nuclei; in some cases there is doubt as to whichproduct of a reaction gives rise to a y-ray. T. W. Boniier andW. M. Brubaker 58 find, by studying the energy distribution of theneutrons, that the reaction 3Li7 + 1H2-+ 2,He* + on1 may takeplace either as shown or with 33e* as an inkermediate nucleus.Li, Be, B, C, N, 0, F, Na, Si, Al, Cu, and Pt all yield radioactiveproducts under deuteron bombardment. The reactions with lithium,boron, and fluorine are probably of ( d ; p ) type : 59 they givep-emitting substances of short period.Nitrogen gives 6o radioactive 015 and oxygen gives 61 radioactiveF17 by ( d ; n) processes, and the identity of the new radio-elementshas been established by chemical tests.The case of Na24, obtainedby a ( d ; p ) process, on bombarding Na23, has been studied exhaust-ively by E. 0. Lawrence.62 This substance may have extensiveapplication, for it has a half life o€ 15.5 hours, and already in 1934Lawrence prepared sources equivalent to about 1 mg. of radium.It gives electrons up to 1.2 M.E.V., and homogeneous y-rays of5.5 M.E.V.The transmutation functions for deuteron bombardment have beenstudied by E. 0. Lawrence, E. McMillan, and R. I;. Thornton 63with very important results.They find that the efficiency of thebombardment of sodium , silicon, and aluminium does not increasewith the energy of the deuterons as rapidly as would be expectedon the Gamow theory of a charged particle penetrating a potentialbarrier. The production of radioactivity in copper by deuteronsaccelerated to less than 3.6 M.E.V. was observed, and it is veryremarkable, since the comparatively heavy nucleus is protectedby a, formidable potential barrier. The processes investigated areall of (d ; p ) type, and a theory worked out by J. R. Oppenheimerand M. Phillips 64 explains the results on the view that the deuteronconsisting of proton and neutron is deformed when it approaches apotential barrier, and the neutron may be captured by the nucleuswithout the proton penetrating the barrier.The theory rests onthe relatively small binding energy, E, of proton and neutron in thedeuteron, and this energy appears as a parameter in the formulaobtained. The formula fits the experiments with E equal to about2.2 M.E.V., which is in agreement with other estimates. It appearsthat quite heavy nuclei may be transformed by deuteron impact,58 Physical Rev., 1935, [ii], 48, 742.59 Crane, Delsasso, Fowler, and Lamitsen, ibid., 47, 887, 971.60 E. McMillan and M. S . Livingston, ibid., p. 452; A . , 559.61 H. W. Newson, ibid., 48, 790.82 Ibid., 47, 17 ; A., 277. 1 3 ~ Ibid., 48,493. 6* Ibid., p. 50124 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.and an artificial radioactivity produced in this way has been reportedfor platinum.neutrons.-A few further experiments have been done directlyon the atomic disintegrations produced by neutron bombardment,using the cloud chamber.W. D. Harkins, D. M. Gans, and W.W. Newson e5 have studied reactions which they consider to be10Ne20 4- onl + *017 + ,He49F19 + on1 --+ 7N1 + ,He4The nucleus $"6 appears to be radioactive. F. N. D. Kurie 66used nitrogen in a cloud chamber and interpreted his results asshowing capture of the neutron and emission of an a-particle. Hesuggests that W5 is formed by capture and disintegrates with a half lifeof about 10-20 sec. He finds that the kinetic energy of the productsof disintegration is independent of the energy of the incident neutron,and suggests that in the capture of the neutron the excess energy isradiated away.This is different from the cases of disintegration pro-duced by a-particles studied by Blackett in which energy is conserved,and Kurie suggests that it is characteristic of neutron disintegration.The reactions in which slow neutrons are captured by boron andlithium have been studied by J. Chadwick and M. G~ldhaber,~~ andby H. J. Taylor and Goldhaber,68 using a new method in which thetracks left by the particles in a photographic emulsion are examinedwith a microscope. The capture of neutrons by a number ofelements with emission of y-rays has also been observed. Thesereactions will be considered below.An enormous mass of results has been accumulated on the pro-duction of radioactive nuclei by neutron bombardment : these areincluded in Table 11.At the end of 1934, Fermi and his co-workers 69discovered that the activation of a large number of elements wasgreatly increased by interposing a body of water or other hydrogen-rich substance around the source and the material t o be irradiated.They correctly attributed the effect to the slowing down of theneutrons by collision with the hydrogen nuclei, and a great deal of65 Physical Rev., 1933, [ii], 44, 945; A., 1933, 1225; 1935, [ii], 47, 52;66 Ibid., p. 97.67 Nature, 1935,135, 65; A., 277; see also B. Kurtschatov, I. Kurtschatov,and G. Latichev, Compt. rend., 1935, 208, 1199.Nature, 1935, 135, 341 ; A., 426; H. J. Taylor, Proc. Physical SOC., 1935,47, 873; A., 1297.6B E.Amaldi, 0. d'Agostino, E. Fermi, B. Pontecorvo, F. Rasetti, andE. Segr6, Proc. Roy. SOC., 1935, [ A ] , 149, 522; A., 910; preliminary reportsin Ric. Sci., 1934, 2, 280, 380, 381, 467; 1935, 1, 123; 0. d'Agostino, Gazzetta,1934, 64,835; A,, 1935,276.A . , 277BRADDICR. 25work has been done on the mechanism of this action and theproperties of slow neutrons.In many cases the radio-elements formed by neutron bombardmenthave been identified by chemical tests.69 It will be seen fromTable I1 that by far the mostl common reaction is a simplecapture of the neutron, giving an isotopic nucleus one unit heavier.This seems always to be the case when the activation is enhanced bywater, and is therefore due to slow neutrons. The capture isoften accompanied by y-emission, which may include y-rays of veryhigh energy.70 In some cases the capture can be demonstrated bythe absorption of the slow neutrons, using a disintegrable substanceas a detector, though the product of capture shows no radioactivityand is apparently a stable nucleus.This is the case with Cd and Y.In the cases of lithium and boron, the bombardment with slowneutrons gives rise to capture 7's and the emission of an ac-particle.These reactions may be used to detect slow neutrons.Some of the products of neutron bombardment are of specialinberest. Fermi and his associates 71 found that the productsof bombardment of uranium with neutrons included radio-elementsnot isotopic with any known element, and which they ascribed toelements with Z>92.A. von Grosse and M. S. Agruss 72 examinedthis view and concluded that it W;LS not valid, but that the elementswere isotopic with Pag1. New evidence has been brought forward fromthe chemical side by 0. Hahn, L. Meitner, and F. Stra~smann,~~ whoshow that the substance of half life 13 minutes is eka-rhenium with2 = 93, and the later paper of Ferrni 69 not only produces new chemicaltests but shows, by the identical water effects on the various activeproducts, that they are probably products of successive transformationThe phenomenon of successive transformation is shown 74 by theseries C137 + n -+ C138 ; A38 -+ S34 + ~ 4 ,and by the elements formed by the irradiation of thorium withne~trons.'~ The series is probably to be represented asgZU + n+ 9ZU+ + P- + PC138 -+ A3* + e- ;'0 F.Joliot and L. Kovarski, Compt. rend., 1935, 200, 824.71 Proc. Roy. SOC., 1934, 146, 483; J4., 1934, 1284.72 Physical Rev., 1934, [ii], 46, 241 ; J . Amer. C'hem. SOC., 1935, 57, 438.73 Naturwiss., 1935, 23, 544; A., 1050.74 W. F. Libby, M. D. Peterson, and W. 111. Latimer, Physical Rev., 1935,[ii], 48, 571.7 5 0. Hahn and L. Meitner, Naturwiss., 1935, 23, 320; A., 910; (Mme.)I. Curie, H. von Halban, end P. Preiswerk, Compt. rend., 1935, 200, 1841,2079; A., 911, 1050; cf. ref. (69)26 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.The chemical behaviour of the activity is consistent with this schemeand the elements belong to the hitherto-unknown radioactiveseries with W = 4n + 1. The rare earths have been investigatedby S.Sugden,76 G. von Hevesy and H. Levi,T7 and J. C. M~Lennan.~~The activations of europium, dysprosium, and holmium are amongthe strongest which have been observed. There are some discrep-ancies which are probably due to the difficulties in separating theseelements.The Transmutation Function for Neutrons and the Speed of SlowNeutrons.-T. Bjerge and C. H. Westcott 79 examined various casesof artificial disintegration, using neutrons from different sources.They found that the reaction 15P31 + on1 + 13A128 + 2He4could not be observed with neutrons of about 2 M.E.V. from thebombardment of deuterium with deuterons, while the reaction15P31 + 14Si31 + lH1 was only reduced to one-third ascompared with an equal number of neutrons from a Ra-Be source(up to 14 M.E.V.).Similar researches,8° using as alternativesources the neutrons from Ra-Be and Ra-8 (up to 4.5 M.E.V.),showed that the (n; a) activation of silicon and phosphorus did notoccur with the slower neutrons, while the reactions 13A127 + on1 --+12Mg27 + lH1, 15P31 + ,,nl --+ 14S131 + lH1 did. P. Preiswerk 81made similar investigations, using the neutrons from Ra + B(up to 6 M.E.V.), and found that the (n; p ) reactions with silicon,aluminium, and iron did not take place, while that with magnesiumdid. For a large number of transmutations, however, the yieldis greatly increased by slowing the neutrons down in a hydrogen-rich material, and Fermi suggested that they were slowed down bymultiple elastic collisions with hydrogen nuclei till they attained‘‘ thermal ” velocities.The correctness of this view has been shownby P. B. Moon and J. R. Tillman’s experiments,82 in which theblock of para& surrounding the test material was cooled withiiquid air. The efficiency of activation in some cases was increasedconsiderably, but the increase was not the same for all elements.The interpretation of the results is complicated by an increasedabsorption of the very slow neutrons in the paraffi itself. Similarresults have been found by Fermi and others.83 A direct proof7 6 Nature, 1935, 135, 469; A., 559; J. K. Marsh and S. Sugden, ibid.,7 7 Ibid., p. 103; A., 1050. 78 Ibid., p. 831. 70 Ibid., 1934,134,177,286.I. Kurtschatov, L. Missovski, M.Erernejev, and G. Schtschepkin, Physikal.Z. Sovietunion, 1936, 7, 257.Compt. rend., 1935, 200, 827; A., 558.82 Nature, 1935, 135, 904; 136, 66; A., 802, 1049; Proc. Roy. Soc., 1936,[A], 163, 476.8a Ric. Sci., 1935,6, 1, 11/12; see also J. R. Dunning, G. B. Pegram, G. A.Fink, and D. P. Mitchell, Physical Rev., 1935, [ii], 47, 796; 4, 266; A,, 1186.136, 102; A., 1050BRADDICK. 27of the velocities of the neutrons has been achieved by Fer~ni,8~by 0. R. Frisch, and by E. T. Spensen,86 who fastened source andtest piece to a rotating wheel surrounded by paraffin and observed akind of aberration effect, and by J. R. Dunning, G. B. Pegram,G. A. Fink, D. P. Mitchell, and E. Segr6,*6 who used a toothed-wheel velocity selector with absorbing sectors of cadmium.The mechanism of the slowing down of neutrons, the cross sectionof the hydrogen nucleus, etc., have been investigated by a number ofworkers.87 It seems that the greater part of the slowing in hydrogenis due to elastic collisions.The efficiency of the slowing process isreduced with heavy water.88 There is, however, another process bywhich neutrons can be slowed down, vix., the excitation of at nucleuswithout capture of the nucleus.89~90~91 It is found that screens ofheavy metals, i.e., gold or lead 90 or silver,g1 do increase the intensityof '' water sensitive " reactions by this process.The cross section for interaction of these slow neutrons withnuclei, as determined by the absorption method, is in many casesvery large (3 x 10-20 cm.2 for gadolinium, 3 x 10-21 cm.2 forcadmium). It varies enormously from element to element, whereasthe collision cross sections for fast neutrons lie on at fairly smoothcurve when plotted against atomic numbers.92 The cross sectionhas been dealt with theoretically by several authors,93 and Bethehas attempted a rather complete theory of the interaction ofneutrons and nuclei, making a straightforward application of wavemechanics.The probability of capture may be large for slowneutrons on account of the long time they spend in the nucleus, andmay be further increased by a resonance factor which cannot bepredicted and varies from nucleus to nucleus. The theory shows(a) that a nucleus may have a large cross section for the elastic134 Ric.Sci., 1935, 6, No. 1, 11-12. 8 5 Nature, 1935, 136, 258; A., 1186.8B Physical Rev., 1935, [ii], 48, 704.87 R. Fleischmann, Naturwiss., 1934, 22, 839; A., 1935, 41; T. Bjergeand C. H. Westcott, Proc. Roy. SOC., 1935, [ A ] , 150, 709; A., 1186; Proc.C a d . Phil. SOC., 1935, 31, 145; A., 426.88 H. Herszfinkiel, J. Rotblat, and M. Zyw, Nature, 1935, 135, 653; A . ,678; C. H. Collie, J. H. E. Grifliths, and L. Szilard, ibid., p. 903.89 D. E. Lea, ibid., 1934, 133, 24; P ~ o c . Roy. SOC., 1935, [A], 150, 637;A., 1186; J. R. Dunning, G. B. Pegram, and G. A. Fink, Physical Rev.,1935, [ii], 47, 325 ; R. Fleischmann, see ref. (87); P. Auger, Compt. rend., 1934,198, 365.90 L. Wertenstein, Nature, 1934, 134, 970.9 1 W. Ehrenberg, Nature, 1935,136, 870 ; B.Kurtschatov, I. Kurtschatov,** Dunning, Pegram, Fink, and Mitchell, Physical Rev., 1935, [ii], 48, 265.03 Amaldi et al., see ref. (69); H. A. Bethe, Physical Rev., 1935, [ii], 47,747; F. Perrin and W. Elsasser, Cornpt. rend., 1935, 200, 460; G. Beck andL. H. Horsley, Phy8icaZ Rev., 1935, [ii], 47, 510.L. Missovski, and I. Roussinov, Cornpt. rend., 1935, 200, 120128 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.scattering of slow neutrons; ( b ) that capture with the emission ofy-rays may take place with large probability if there is a suitablevacant neutron level in the nucleus-in the absence of resonancethe probability of capture decreases inversely as the velocity ;(c) that disintegration with emission of a-particles may take placewith high probability if the process is exothermic and the potentialbarrier opposing the exit of the a-particle is not too high-for thisreason it is confined to light elements-(%; p ) disintegration isalways endothermic and does not take place with slow neutrons;(d) that excitation without capture may also occur.It is, how-ever, incomplete, since evidence is appearing that the crosssection of different nuclei can vary in different ways with theneutron velocity.This appears strongly from the experiments ofMoon and Tillmans2 and from those of Fermi and Amaldi,94 inwhich an absorber is shown to absorb selectively (a) the neutronswhich activate it and ( b ) some other bands of neutron energy.y-Rays (NucEeur Photo-eflect).-The reactions 1H2 + hv -+lH1 + ,,nl, ,Be9 + hv -+ ,Be8 + ,,nl have been confirmed andfurther st~died.~5 Arzimovitch and Palibin find that the latterreaction does not proceed with y-rays of energy less than 1.3 M.E.V.Electrons.-Some reports have been made of an artificialradioactivity produced in aluminium by fast electron bombard-ment.96 No activity was found by Livingood and Snell after850-kv. bombardment, and this disintegration by electrons doesnot seem very likely.TABLE 11.Nuclear Reactions and Radioactive Transformations of LightNuclei (References in parentheses).This theory collates many of the known facts.lH1 + on1 _3 1H2 + y (89)1H2 + y 1H2 + lHa --+ ,He3 + onl (33)1H2 + 1H2 -+ 1R3 + IH1 (33),Li6 + on1 --+ $3' + 2He4!61V)-> lH1 + on1 (95),Lis + --+ ,He3 + ,He (,Lie + 1H2 _j 2,He4 + y (49),Li6 + ,He4 -+ 5BQ + onl (98, 99).e+B9 i--z BeQ94 Ric.Sci., 1935, 6, ii, 9/10.Q5 J. Chadwick and M. Goldhaber, Proc. Roy. SOC., 1935, [A], 151, 479;A., 1293; cf. A., 1934, 1053; W. Gentner, Cornpt. rend., 1935, 200, 310;L. Arzimovitch and P. Palibin, Physikal. 2. Xovietunion, 1935, 7, 245.96 M. Tenaka, Physical Rev., 1935, [ii], 48, 916 ; J. J. Livingood and H. H.Snell, ibid., p. 851.97 Rutherford, Chadwick, and Ellis, " Radiations from Radioactive Sub-stances," Cambridge, 1930.98 Ann. Reports, 1934. 99 Ibid., 1933BRADDTCK. 29TABLE IT. cont.,Li7 4- lH1 --+ 2,He4 + y (49, 48),Li7 + 1H2 _j 2,He4 + (49),Li7 + 1H2 --+ ,Be8 -t- +Z,He4 + o ~ ~ l (58),Li7 + 1H2 + ,Li8 + lH1 (49, 59).&!7 + ,He4 + , B I O + on1 (98, 99),L17 + ,He4 (excitation) (42), T i 7 + ,He4 _j Belo + lH1 (95).,Be9 + y,Be0 -1- lH1 4 ,Belo + y (98),Be9 + 1111 _j ,Lis + ,He4 (98),Be0 + lH6 --+ 5B.10 + on1 + Y (57),Be9 + 1H2 _3 ,L17 + ,He4 (98),Be0 + 1H2 + ,Belo +,Be9 + ,He4+ 6C12 + on1 (98, 99, 57)BLi8 -+ Be8+2He40.5 sec.PBelo --+ Bl0 ?-j- ,Be8 + on1 _j 2He4 + on1 (95)B(98). Belo -+ BIO ?+ onl + ,Li7 + ,Hc4 (67)e+5Bl0 {- 1H2 6C1l f 0,' (98).6C1l aomz 5Bl16131" + 1H2 --+ 5Bl1 + lH1 (98)5B10 + 1H2 + 3,He4 (98)5B10 + ,He4-> 7N13 (98). 7N13 &l'*,B10 + ,He4-+ + y + lH1 (97)-Bll -b lH1 _3 3,He4 (98)iB11 + lH1 __t ,Be8 + ,He4 --+ 3,He4 (98)5B11 f- 1H2 4 GC12 + ,nl f y (56),B1l + 1H2 --+ 3,He4 + (98)5B11 + 1H2 + ,Be9 + ,He4 (98)efB0.02 sec.$11 + H2 + 5B12 + lH1 (59). 5B12 - 3 c12ef7N13 ~ ~ 2 . 6C1'*6c12 + 1H2 --+ 7N13 + lH1 (98) do.:C12 + 1H2 -+- bB1o + ,He4 (98)7N1* + on1 -+ 5B11 + ,He (98, 99)6C12 + lH1 + 7N1' + y (45, 46)..C12 + 1H2 -> GC1s + y (98)7N14 f lH17N14 + --+ *015 + on1 (GO). ---.-+ N15_3 6C1l + ,He4 (98)e+126 sec.7N14 + 6Ha7N14 + 6H2C j 7 W 6 + lH1 (54, 55)_t 6c1' f ,He* (54, 55)e+,N14 + ,He4 _t sF17 + o ~ ~ l (41).7N14 + ,He4 -+ 8017 + lH1 (97)8 0 1 6 + lH1 + sF17 + onl (61). 9F17 ---+ Oi79 ~ l w + o ~ lSFIS + on1 + sN16 + ,He4 (65). 7N16 8 0 l 6BF1° + lH1 -+ loNe20 + y (98)oF19 + lH1 4 * 0 l 6 + ,He4 (98)9F1e + 1H2 + 8 0 1 7 -f- 2 ~ ~ e 4 (98)9F17 lym-. 8 0 l 7e f1.2 min.B + 8 0 1 9 + lH1 (59).8010 --f gF1O 40 sec.BgF1s + 1H2 + 1oNe2O f Y (9830 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.TABLE 11. cont.e+llNa22 -+ loNe22 > 6 months DF19 + ,He4 + 11Na22 + on1 (38).,FIB + ,He4 --+ loNe22 + lH1 (97)loNe20 + onl + + ,He4 (65, 99)BllNa24 F~? I z M ~ ~ ~ 11Na23 + on1 + 11Na24 (69).11Nae3 + on1 4 + lH1 (69). 10Ne23 csz llFa23,,Naa3 + lH1 + loNe20 + 2He4 (27)'B11N~23 + 1H2 --+ 11Naa4 + lH1 (62). $a2' ljd 12MgZ4llNrt23 + 1H2 --+ lzMga4 + on1 (62)11Naa3 + 1H2 -+ loNe21 + ,He4 (62),,Nae3 + ,He4+ 12Mg26 + lH1 (97, 98)11Na23 + ,He4+ 13A126 + on1 (98, 99)12Mg24 + on1BB -+ 11Na24 + lH1 (69). llNa24 --+ 15h.lzMg94 + 1H2 4 11Na2z + ,He4 (2)12Mg24 + ,Me4 -j 14Si27 + on1 (36). 1pSi27 T+12Mg24 + ,He4 + 13MZ7 + lH1 (97)B 12Mg25 f ,He4+ 1 3 u 2 ' + 1H' (36).l ~ x ~ ~ a 14s12812Mgas + on1 -+ 12Mg27 (69). 12Mg27 <+ 1sM2',,Mg26 + onl + 10Ne23 + ,He4 (69). --f llNa2340 sec.12Mga6 + lH1 -+ 11Na23 + 4He4 (2)B12Mg26 + ,He4+ ,3A129 + lH1 (36). 1 3 x 2 ' -313A127 + ,nl -+- 13M2' (69). 2ym-s 14Si281 3 ~ 1 2 7 + on1 + 12Mg2' + lH1 (69). 12Mg27 cmi;;. 13AJ27e+BBBBllNa24 ---+ 1zMg2415 min. laA127 + ,nl --+ llNa24 + ,He4 (69).1 3 u 2 ' + O H 113A127 + 1 H 2 + 1H2+ izMgrP 4- ,He4 (2)+ 13A.I" + lH1 (1). + l2MgZa + ,He4 (1)1 3 d 2 ' + rH2 + 14Si2' + om1 (1)B 13A128 -9 Si2'ef2-1 min.I&'' + ,He4 + + on1 (98). I5P3O a1 3 ~ i 2 7 + ,He4 -+ 14Si30 + IH1 (97, 98)For elements of 2 > 13, see Table 111, but also :14Si27 + ,HeO4 -+ 15P32 + lH1 (34)20Ca40 + ,He4 --+ Sc43 + IH1.21Sc43 r-6 (38)ef1 E. McMillan and E. 0. Lawrence, PhysimZ Rev., 1935, [ii], 47, 343.M. S. Livingston, M. C. Henderson, a-d E, 0. Lawrence, ibid., 1933,[ii], 44, 316BRADDICK .TABLE 111.Artijicial Radioactivity produced by Neutrons.References not marked are to Fermi et al. (40, 69). The carrier of theThe mark * indicates that the activity activity and the half life are given.is enhanced by water and is probably due t o (n; -) transformation.1 H2 He3 Li4 Be5 B6 C7 N8 09 F10 No11 Na12 Mg13 Al14 Si15 P16 S17 C118 A19 K20 Ca21 sc22 Ti23 V24 Cr25 l\ln26 Fe27 Co28 Ni29 Cu30 Zn31 Ga32 Ge33 As34 se35 Br36 Kr37 Rb38 Sr39 Y40 Zr41 Nb42 Mo43 Ma44 Ru45 Rh46 PdOle 40 s., N16 9 s.N@ ~ O S ., Mgz7 lorn.,40 s., NaZ4 15 h.NaZ4 15 h.A 1 2 8 2-3 m., Mga7 10 m.,Na24 15 h. (cf. 97).Si31 2.4 h., A128 2.3 m.Alas 2.3 m., Si31 2.4 h.P32 14 d.C135 m., P32 14 d.K42 16 h.Ca 4 h., K42 16 h. (5)K42 16 h.VS2 3.75 m.V52 3.75 m.Mn56 2-5 h., V52 3-75 m.34x156 2.5 h.Co60 20 m., MnS6 2.5 h. (4)Ni ( ? hr.), C060 20 m. (4)Cu 5 m., Cu 10 h.Cu B m., Cu 10 h., Zn*Ga 20 m. ? 23 h.30m. ?As76 26 h.Se 35 m.Br 18 m.. Br 4.2 h.100 m. ( 5 )Zr 40 h. (5)30 in. 36 h.40 s., 100 s., 11 h., 75 h. (8)Rh 44 s., Rh 3-9 m.Pd, Fyh, ? 15 m.3147 Ag Ag 22 s.*, Ag 2.3 m.48 Cd49 In In 54 m., In 3 h., ? 13 s.50 Sn51 Sb Sb 2.5 d.52 Te Te* 45m.53 I I 2 5 m .54 Xe55 Cs Cs* 75 m.(7, 6)56 Ba Basom., ? 3m.57 La 1.9 d. (10)58 Ce59 Pr Pr* 19 h. (cf. 10)60 Nd61 -62 Sm 40 m. (cf. 10)63 EU 9.2 h. (10)64 Gd 8 h. none (10)65 Th 3.9 h.66 Dy 2.5 h. (10, 11)67 HO 2-6 h. (lo), 35 h. (11)68 Er 7 m., 1.6 d., 12 h. (11)69 Tu70 Yb 3-5 h. (10, 11)71 LU 4.0 h.72 Hf Hf (months) (5)73 Ta74 W W Id.75 Re Re 20 h.76 0 s77 Ir Ir 19 h., 3 d. 50 m. (12)78 Pt ? (13)79 Au AU 2.7 d.80 Hg81 T1 T1* 97m. (6)82 Pb83 Bi Bi (6)84858687888990 Th 1 m., 24 m. (cf. p. 25).9192 U 15 s., 40 s., 13 m., 100 m.93(Cf. 9).(cf. p. 25).3 I. Kurtschatov, B. Kurtschatov, L. Missovski, G. Schtschepkin, and A.Vibe, Compt. rend. Acad. Sci., U.R.S.S., 1934, 3, 422.4 J. Rotblat, Nature, 1935, 136, 515; A , , 1297.6 J.C. McLennan, L. G. Grimmett, and J. Read, Nature, 1935, 135, 505;G. von Hevesy and H. Levi, ibicl., 135,580; A , , 678.A., 67832 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.3. THE RAY DISINTEGRATION.Not much definite progress seems to have been made in testing thetheories of @-decay which were described in last year’s Report.15The Fermi theory has been criticised theoretically by R. L. Dolecek,16who develops a method allowing the calculation of the energydistribution of the p-electrons for any appropriate assumptionsabout the transfer of angular momentum from the nucleus to theemitted particles. He was unable to account for the shape of thep-ray energy distribution in the cases of the relatively heavy nucleiof potassium and rubidium, and supports the necessity for additionalassumptions in the theory.E. J. Konopinski and G. E. Uhlenbeck17introduce a new weight factor into Fermi’s treatment and find thatthe new distribution, which should hold strictly only for lightnuclei, fits more satisfactorily to the experimental curves for thepositrons from F30, N13, and the electrons from A128. The experi-mental data were provided by the work of C. D. Ellis and W. J.Henderson l8 and of A. J. Alichanov, A. J. Alichanian, and B. S.Dielepov,lg and the agreement between the results of the two setsof workers was not very good, though both show the asymmetrywhich is a characteristic of the modified theory.Much attention has been coiicentrated on the high-energylimit of the @-ray continua.The view was put forward by C. D.Ellis and N. F. Mott 2o that the upper limit of the continuumrepresents the energy available for the p-ray in every case of agiven nuclear transition. When a p-ray of lower energy is emittedthe surplus energy is carried off by a (‘ neutrino.” This view hasbeen supported by the experiments of W. J. Henderson,21 who usedW. M. Latimer, D. E. Hull, and W. 3’. Libby, J . Arner. Chew. Soc., 1935,I . Kurtschatov, L. Nemenu, and I. Selinov, Compt. rend., 1935, 200,L. Szilard and T. A. Chalmers, Nature, 1935, 135, 98; A., 271.57, 781; A., 678.2162.lo S. Bugden, ibid., p. 469; A., 559; J. K. Marsh and S. Sugden, ibid.,l1 G. von Hevesy and H. Levi, ibid., p. 103; A., 1050.l2 L. Sosnowski, Compt.rend., 1935, 200, 922; A., 678.l3 Idem, ibid., p. 446; A., 426.Ann. Reports, 1934, 31, 394.Physical Rev., 1935, [ii], 48, 13 ; A., 1048.l7 Ibid., pp. 7, 107; A,, 1048.Proc, Roy. SOC., 1934, [A], 146, 206.l9 2. Physik, 1935, 93, 350; A., 426.2o Proc. Roy. SOC., 1933, [A], 141, 502; A., 1933, 1100; see also Ann,21 Proc. Roy. SOC., 1934, [ A ] , 147, 572; A . , 276; cf. P.C. Ho, Proc. Carnb.136, 102; A., 1049.l4 Idem, ibid., p. 1027 ; A., 559.Reports, 1934, 31, 394.Phil. Soc., 1935, 35, 119BRADDICK. 33a coincidence Geiger counter in conjunction with a magneticspectrograph to study the high-energy end of the thorium-C and-C”’ spectra. He found that the energy changes in the branchedprocesseswere equal if the upper limit were taken as the energy of theP-transformation and the y-ray energy properly allowed for.Ellisand Henderson 22 studied the positrons from the artificial radio-active nucleus P30, using an absorption method, and they assumethat the upper limit of the spectrum gives the difference in energybetween the ground states of P30 and its disintegration productSi30, since no y-rays were emitted in the disintegration. Thisassumption can be checked by equating the energies in the two setsof processes : 2313A127 + zHe4 = 14Si30 + lH113A127 + 2He4 = 15P30 + on113P30 = 14Si30 + E+It is therefore probably true that the Ellis-Mott rule holds for bothheavy and light nuclei, electron and positron emission. IE. R.Crane, L. A. Delsasso, W. A. Fowler, and C.C. Lauritsen24 drew thesame conclusions by studying the electrons produced by bom-barding boron with deuterons :Bll + H2 -+ B12 + H1-+ C12 + E- 4- H1The masses are here determinable by other nuclear reactions, andthe upper limit lies at about 11 M.E.V.The upper limiting energies have also been studied from thepoint of view of the empirical Sargent rule,25 which connects thelogarithm of the limiting energy with that of the decay period byone of two nearly linear relations. One of these is supposed to holdfor “ allowed ” and the other for “ forbidden ” nuclear transitions.The theory was also tested by F. N. D. Kurie, J. R. Richard-son, and H. C. Paxton26 with the electrons from radio-sodium,Naw, and radio-silicon, and satisfactory agreements were obtained.The distributions obtained by Crane, Delsasso, Fowler, andLauritsen 27 for the electrons obtained on bombarding lithium and22 Proc.Roy. SOC., 1936, [ A ] , 152, 714.23 L. Meitner and R. Jaeckel, 2. P h y ~ i k , 1934, 91, 493.3% Physical Rev., 1935, [GI, 47, 887.26 For a recent modification, see G. J. Sizoo, Nature, 1935,136,142 ; A., 1048.0 6 Physical Rev., 1935, [ii], 48, 168. 27 lbid., 4’9, 971.REP.-VOL. XXXII. 34 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.fluorine with deuterons also fit the relation for the energydistribution. The experimental data on the artificially activeelements are conflicting. Alichanov, Alichanian,22 and D%elepov,28who have examined a number of elements, conclude that their resultsdo not fit on the Sargent lines. An absorption estimate byLawrence 29 of the maximum energy of the @-particles from radio-sodium, Na24 (1.2 M.E.V.), fits on the curve, and the results of Craneet aL2' for the short-lived products of bombarding lithium (probablyBes) and fluorine seem to fit fairly well.Kurie, Richardson, andPaxton 26 use a theoretical energy-distribution curve to estimate theend-points for C, Si, and Na. Na (2-1 M.E.V.) is in rather markeddisagreement with Lawrence, and does not fit on the curve; siliconseems to fit tolerably well. The unpublished results of R. Naidu andR. E. Siday for rhodium, silver, and fluorine agree with the rule, butsilicon, dysprosium, and europium do not; the probable errors arelarge, however. It is clear that the experiments are still inadequate.The low-energy end of the @-ray spectrum of radium-E hasbeen studied by H.0. W. Richardson,30 who finds an unexpectedlylarge number of slow particles. It is uncertain how far these areof secondary origin. It has been pointed out that many modernviews on the continuous F-spectrum require a neutrino to carryoff unobserved a part of the energy, and a few further attempts 31have been made to detect this particle. H. A. Bethe 32 has made acalculation of the ionising power of a neutrino possessed of magneticmoment, and in conjunction with the negative results of the experi-ments this shows that the magnetic moment cannot exceed 2 x 1o-PBohr magnet on.4. THE POSITRON.The positron was treated rather fully in last year's Rep0rt.3~Positrons have been found in the cosmic radiation; positron-electron pairs are created by the transformation of the energy of hard7-rays and perhaps fast electrons in the neighbourhood of an atomicnucleus, and they are annihilated by combination with an electron,with emission of radiation.During 1935, considerable attentionwas devoted to calculating the probability of production of a pairby interml conversion of a 7-ray emitted by a nucleus in its own28 Nature, 1935,136, 257; 1935, 135, 393; A., 426, 1186; see also ref. (19).29 LOC. cit., ref. (62).30 Proc. Roy. Soc., 1934, [ A ] , 147, 442; A , , 1935, 6.31 J. Chadwick and D. E. Lea, Proc. Camb. Phil. SOC., 1934, 80, 59; A.,1935, 276; M. E. Nahmias, ibid., 1935, 31, 99; A., 426; M.Wolfke, Bull.Acnd. Polonaise, 1935, [ A ] , 107; A., 911.32 Proc. Carnb. Phil. SOC., 1935, 31, 108; A., 426.33 Ann. Reports, 1934, 31, 397BRBDDICK. 35atom.= Jaeger and Hulme calculate the internal conversioncoefficient for element 84 for both dipole and quadruple transitions.There is in this case a marked difference between the averageenergies of the positrons and electrons emitted, the former havinggreater energies, while for light elements there should be a symmetricdistribution of energies between the particles. The number ofconversions predicted is in agreement with the results of A. J.Alichanov and M. S. Kosodaev 35 on the emission of positrons fromradioactive sources. H. J. Bhabha, 36 has calculated the probabilityof pair production by collision of charged particles.The annihilation radiation due to the combination of an electronand a positron has been studied experimentally by 0.Klem~erer,~’who used the positrons from artificially radioactive elements anddetected the radiation with two Geiger counters in a coincidencecircuit. He found that in the normal annihilation process twoy-ray quanta are emitted in opposite directions. The energyavailable for each quantum is then wix2 = 0.5 M.E.V., and absorptionmeasurements on the radiation were consistent with this. Theannihilation has been dealt with theoretically by H. A. Bethe,38who calculates that a fast positron has rather a high probability ofbeing annihilated during its motion, the energy being usuallyemitted as a pair of quanta (cf.ref. 37). There is, however, anappreciable probability of a single-quantum annihilation in theneighbourhood of a heavy nucleus. The annihilation of slowlymoving positrons takes place almost entirely with emission oftwo quanta. (This process is the one which would have beenobserved in Klemperer’s experiments.)The part played by the annihilation process in the anomaloushard scattering of 7-rays is discussed by Bethe 38 and by E. J.Williams39 and K. Tsu T~ng.~o The present view appears tobe that the hard scattered radiation contains a broad band due toannihilation, since the annihilation radiation carries off the energyof motion of the positron as well as the annihilation energy itself.There is also present an important component due t o the radiationemitted in the slowing down of Compton and pair electrons.34 M.E. Rose and G. E. Uhlenbeck, Physical Rev., 1935, [ii], 48, 211; A,,1187; J. R. Oppenheimer, ibid., 47, 144; A., 278; J. C. Jaeger and H. R.Hulme, Proc. Roy. SOC., 1935, [ A ] , 148, 708; A., 557.36 2. Physilc, 1934, 90, 249; A., 1934, 1150.36 PTOC. Roy. SOC., 1935, LA], 152, 559; cf. L. Nordheim, J . Phys. Radium,1935, [vii], 6, 135; A., 677; L. Landau and E. Lifschitz, Physiknl. Z. Soviet-union, 1934, 8, 244; A., 677.37 Proc. Garnb. Phil. SOC., 1934, 30, 347; A., 279.38 Proc. Roy. SOC., 1935, [ A ] , 150, 129.40 Sci. Rep. Nat. Tsing Hua Univ., 1935, 3, 85.39 Nature, 1935, 135, 26636 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.5. THE RADIOACTIVITY OF POTASSIUM.The discovery of widespread neutron-induced radioactivity hasenabled the problem of the natural activity of potassium andrubidium to be approached from a new angle.The activity of theseelements is extremely weak, and it is now generally ascribed torare isotopic constituents. Several papers 41 have appeared inwhich the activities are ascribed to K40 and Rbs5. These substancescould have been formed in pre-terrestrial times by neutron bom-bardment of K39 and Rb85 and persist only in traces undetectableby the mass spectrograph. Von Hevesy finds that bombardmentof scandium with neutrons gives K42 by the transition 21Sc45 +on1 -+ 19K42 + 2cx4; K42 decays with a 16-hour period and isexcluded as the naturally occurring radioactive constituent.K.Sitte 42 oonsiders, on mass-energy grounds, that K40 shouldshow a positron activity as well as the @-activity, and since hedetects no positrons, he ascribes the potassium activity to K43.Von Hevesy, however, finds that the assumption of Ka fits hisdata on the activity of the fractionated isotopes of potassium.Evidence for the existence of K40 has recently been found with themass-spectrograph by A. 0. Nier,43 who finds K40: K39 = 1 : 8600,and by A. K. Brewer,M who finds K40: K39 = 1 : 8300. Evenassuming that the activity is due to rare isotope, the persistenceof the activity over very long periods cannot be connected withthe energy of the p-rays by the Sargent relation.25 Klempererconsiders that K40 probably has a large nuclear spin, and that thetransition to Ca40 is a kind of ‘‘ super-forbidden ” one for which alow probability is to be expected.456.THE PENETRATING RADIATION.Nothing has been discovered during the year to disturb theconclusion that the primary cosmic radiation consists mainly,and perhaps entirely, of charged particles. W. F. G. Swann46says that the variation of intensity with latitude, due to deviationin the earth’s magnetic field, indicates that at least 25% ofthe incident radiation is of charged corpuscular type, and that theobservations of the east-west asymmetry of the radiation in the4l 0. Klemperer, Proc. Roy. Soc., 1935, [ A ] , 148, 638; G. von Hevesy,Nature, 1935, 135, 96; A., 276; A. Ruark and K. H. Fussler, Phy8icaZ Rev.,1935, [ii], 48, 151; A ., 1185; F. H. Newrnan and H. J. Walke, Nature, 1935,135, 98, 508; A., 677; Phil. Mag., 1935, [vii], 19, 767; G. von Hevesy,Nctturwiss., 1935, 34, 583.42 Nature, 1935, 136, 334.41 Ibid., p. 640.4 6 Physical h’ev., 1935, [ii], 48, 641.43 Physical Rev., 1936, [ii] 48, 283.45 Cf. C. Hurst, Nature, 1935, 135, 905BRADDICR. 37equatorial region brings this value up to 31%. A. H. &mpton,47relying largely on a balloon measurement of the cosmic rays inequatorial considers that at least 97% of the rays arecharged, and an extrapolation of the data to the top of the atmo-sphere indicates that 99% are charged. Analyses of the generalnature of the rays have been made by Compton49 and by Swann.Compton attempted an analysis of the rays, starting with theintensity-height data obtained on balloon flights.When allowancehas been made for the isotropic incidence of the rays on the top ofthe atmosphere, these curves show kinks which are interpreted asdue to the successive removal of groups of particles of finite range.An application of the theory of the magnetic deviation of the particlesin the earth’s field gives the minimum energy which the particlesmust possess to reach the earth’s atmosphere a t all. Combiningthese data, and assuming (rather uncertain) relations between therange and energy of different kinds of fast particles, Comptonascribes one of his range groups to a-particles, one to electrons, andone to protons. The showers of particles detected with counterarrangements and in the Wilson chamber are regarded as producedby a secondary radiation. A difficulty in the theory lies in the factthat protons have not been distinguished in Wilson chamberphotographs a t sea level, though they should theoretically be present.Swann considers that the charged particles which constitute theprimary rays come right through the atmosphere; possibly notionising directly, but producing long-range secondaries throughouttheir path.These secondaries are those observed in Geiger-countermeasurements. The theory in this form gives an exponential lawfor the absorption of the measured radiation if we assume that thenumber of secondaries produced per unit length of primary path isproportional to the energy of the primary.The comparativelysmall departures from the exponential law may be explained by adistribution of the primary energy. The fact, discussed below,that showers and bursts increase more rapidly with altitude than thegeneral radiation, is explained on the assumption that, althoughsecondary production in air increases linearly with the energy of therays, yet secondary production in lead increases more rapidly thanthis.Extensive experimental work has been done on the cosmicradiation. The assumption usually made, that the coincidences ofa set of Geiger-Muller counters in line represent the passage of47 Guthrie Lecture, Proc. Physical SOC., 1935, 47, 747.48 J. Clay, Physica, 1934,1, 363.49 A. H. Compton and H. A. Bethe, Nature, 1934, 134, 134; see also ref.(47)38 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.a single ionising particle through the system, has been checked.60Absorption data for various materials have been obtained.51Auger and his co-workers interpret their results as indicating thepresence of a hard and a soft component which may perhaps beidentified with protons and electrons respectively.An analysis by C. G. and D. D. Montgomery 52 shows that there isno sharp distinction between the (‘ showers ” which discharge Geiger-counter systems and the large “ Stosse ” observed in ionisationchambers. Unpublished work by W. Ehrenberg and by I€. Car-michael also tends to this conclusion. Several sets of experimentsshow that showers and bursts increase more rapidly than the generalcosmic radiation with increase in 53 and unpublishedwork in an aeroplane by H. J. J. Braddick and C. W. Gilbert showsthis very markedly. These experiments either demand a special“ shower-producing component ” of the radiations, or they are tobe explained slow the lines indicated by Swann. A very recentpaper by C. G. and D. D. Montgomery 54 indicates that the rate ofburst production varies differently with altitude for differentmaterials, and this produces severe difficulties for the “ showerproducing radiation ” hypothesis. New data on the variation ofshower production with thickness of material have appeared. 55E. C. Stevenson and J. C. Street 56 have published photographsshowing showers apparently produced in a lead plate by incidentelectrons. This is a new type of shower production, previouswork having led to the conclusion that showers were always producedby a non-ionising radiation. T. H. Johnson 57 has continuedwork on the directional distribution of the cosmic rays, findingan unbalanced positively charged component of the incomingradiation.H. J. J. BILADDICK.50 J. C. Street, It. H. Woodward, and E. C. Stevenson, PhysicaZ Rev.,1935, [ii], 47, 891 ; A., 1050.51 J. Clay, Phyeica, 1935, 2, 645; A., 1050; H. Tielsch, 2. Phyeik, 1934,92, 589; A., 143; G. Alocco, Nature, 1935, 135, 96; A., 278; P. Auger,Compt. rend., 1935, 200, 739; A., 560; P. Auger, A. Rosenborg, and F.Bertein, ibid., p. 1022; A., 660; P. Auger, L. Leprince-Ringuet, and P.Ehrenfest, ibid., p. 1747; A., 1050.62 Physical Rev., 1935, [ii], 48, 786.63 B. Rossi,and S. de Benedetti, Ric. Sci., 1934, 2, 5, 95, 119; A., 804;E. C. Stevenson and T. H. Johnson, Physical Rev., 1935, [ii], 47, 678; A.,803; R. D. Bennett, G. S. Brown, and H. A. Rahmel, ibid., p. 437; A . , 560;C. G. Montgomery and D. D. Montgomery, ibid., p. 429; A., 560.Ibid., 48, 969.65 J. E. Morgan and W. M. Nielsen, ibid., p. 773.66 Ibid., p, 464. 6 7 Ibid., p. 287

ISSN:0365-6217    

DOI:10.1039/AR9353200015

出版商:RSC    

年代:1935

数据来源: RSC

摘要:

GENERAL AND PHYSICAL CHEMISTRY.1. INTRODUCTION.THE choice of subjects in this Report has of necessity been dictatedby personal, as well as by scientific, considerations. The chemistryof deuterium compounds continues to attract attention, and a reporton this subject appears inevitable. The price of “ heavy water ”has fallen so considerably during the current year as to make thesubstance a relatively cheap reagent. Attention may be called totwo publications : a review, with about 400 references, by H. C.Urey and G. K. Tea1,l and a book by A. Farkas.2 The successfulseparation of deuterium has stimulated interest in other isotopes,and it is not improbable that waters enriched with H3 and with0ls will shortly be available for experimental investigation. Mentionmust be made of the fact that the artificial radioactive isotopes oflight elements are already being used in the study of chemical andbiological problems.Articles on aspects of spectroscopy have appeared in the twoprevious Reports : in the present Report the spectra of polyatomicmolecules and of deuterium compounds are the main considerations,since important advances have been made in these directions.The publication of two books on the subject likely to be of interestto chemists, by Frl.H. Sponer and by R. de L. K r ~ n i g , ~ must berecorded.Statistical methods for calculating thermodynamic functionshave been known for some time, but only in recent years, as a resultof developments in wave-mechanics and in spectroscopy, has itbecome possible to evaluate quantities of direct use t o the chemist.The principles involved in the calculations have become especiallyimportant in the study of isotopic exchange processes and for theoriesof reaction velocity, and a report on the subject is overdue.Thenecessity for an annual report on chemical kinetics is obvious inview of the interest being taken in the subject by workers in suchwidely different fields of chemical activity. Two books on kinetics, by1 Rev. Mod. Physics, 1935, 7, 34.2 “ Ortho-Hydrogen, Pars-Hydrogen, and Heavy Hydrogen,” Cambridgea “ Molekulspektren,” Springer, Leipzig, 1935.4 ‘‘ The Optical Basis of the Theory of Valency,” Cambridge UniversityUniversity Press, 1935.Press, 193640 GENERAL AND PHYSICAL CHEMISTRY.F. 0.Rice and K. K. Rice,5 and by N. Semenoff,G have been publishedduring 1935, and are likely to have an important influence.There has been no specific consideration of surface chemistry forsome years, and consequently certain aspects are discussed in thepresent Report. The enunciation of a theory of optical rotatorypower, by M. Born,‘ which marks a definite advance, and theappearance of a book, likely to become a classic, by T. M. L o w r ~ , ~during the current year, indicated that a short review of opticalactivity, from the physical, rather than the organic, standpointwould not be out of place. Dipole-moment data have been used todetermine the angles between the valency bonds, especially foroxygen and sulphur, but the situation has been confused: theintroduction of new concepts has done much to clarify the positionand it is now possible to consider the value and the limitations ofthe method.I n conclusion attention may be called to the issue of a new journal,in English, French, and German, vix., the Acta Physicochimica,U.R.S.X.The Reporter feels that some apology is necessary forthe omission of such topics as the quantum theory of valency,electron diffraction, photochemistry, the physical chemistry ofsurface films, and colloids, but these must be left for a subsequentoccasion. S. G.2. ISOTOPES.The electrolytic method of preparingdeuterium has continued to attract attention, because, not only isit still the best means of obtaining the heavy isotope of hydrogen,but also the separation involves matter of great theoretical interest.A number of arrangements have been described for carrying out theelectrolysis,l and although alkaline electrolytes have been mostlyused, it appears that equally good results can be obtained with acidDeuterium.-Separation.5 “ Aliphatic Free Radicals,” Johns Hopkins Press, Baltimore, 1935.6 “ Chemical Kinetics and Chain Reactions,” Oxford University Press,7 Proc.Roy. SOC., 1935, [ A ] , 150, 84.8 “ Optical Rotatory Power,” Longmans, 1935.1 &I. Harada and T. Titani, Bull. Chem. SOC. Japan, 1934, 9, 457; A . ,1935, 44; E. W. Washburn, E. R. Smith, and F . A. Smith, J . Res. Nat. Bur.Stand., 1934, 13, 599; A., 1935, 175; P. Goldfinger and J. Scheepers, J .Chim. physique, 1934, 31, 628; A., 1935, 311; B.Kamieriski, Rocz. Chem.,1934, 14, 401; A., 1935, 311; W. G. Brown and A. I?. Daggett, J . Chem.Physics, 1935, 3, 216; A . , 723; H. C. Urey and M. H. Wahl, PhysicalRev., 1935, [ii], 45, 566; A., 1329; H. Erlenmeyer and H. GZirtner, HeEz).C h i w ~ Acta, 1935, 18, 419; A., 589.1935GLASSTONE : ISOTOPES. 41solutions.2 The previous theoret icnl treatments of the separationcoefficient have been based on the view that an energy barrier pre-vents the passage of electrons from the cathode into the solution :it has now been shown that separation factors of the correct order,vix., 10 -+ 5, may be calculated by assuming the rate of productionof gas on electrolysis to be dependent, a t the current densities used,on the speeds of recombination of hydrogen and deuterium atoms,to form molecules, on the ele~trode.~ It is becoming increasinglyevident that the differing experimental values for s obtained underapparently identical conditions are due to variations in factors notyet fully understood which occur during the process of electrolysis.5For different metals, s appears 60 vary from 2.7 to 17 : there is noobvious connexion between the separation factor and the over-voltage of the cathode.Anodic prepolarisation of the latter increasess, and addition of a-naphthaquinone decreases it. By raising theC.D., the value of s is generally increased, but this is not alwaysthe case.6 A fundamental difficulty which may account for dis-crepant observations is the tendency towards the establishmentof the equilibrium H, + HDO e H , O + HD, since this wouldlead to a factor of about 3.8 in every case.Slight variations in thecatalytic activity of the electrode material for this process wouldbring about marked changes in the experimental results.As the deuterium content of the electrolyte is increased, s evidentlytends towards the value required by the complete establishmentof equilibrium, even at nickel cathodes. With only slightly enrichedwater, however, containing 1 part of deuterium oxide in about 3000parts, a factor as high as 100 has been claimed, based on the assump-tion that normal water contains 1 part of deuterium oxide in 5500.This result 8 is of great importance, since theoretical considerations,in which the possibility of quantum-mechanical leakage throughan energy barrier-the " tunnel effect "- is neglected, lead to theexpectation of a value of s less than 20, whereas much higher factorsshould be possible if " tunnelling " can occur.g Although somea A.I. Brodski et al., Compt. rend. Acad. Sci. U.R.S.S., 1934, 3, 615; A.,1935, 44.9 Ann. Reports, 1934, 31, 20; W. W. Sawyer, Proc. Cnmb. Phil. SOC., 1935,31, 116 ; A., 456.4 H. C. Urey and G. K. Teal, Rev. Mod. Physics, 1935, '7, 44; 0. Helpernand P. Gross, J . Chem. Physics, 1935, 8, 452; A., 1210; see also H. Eyringand J. Sherman, ibid., 1933, 1, 345.8 Private communication from Mr. J. H. Wolfenden.6 A. Eucken and K. Bratzler, 2. physika2. Chem., 1935, 174, 279.7 Ann.Reports, 1934, 31, 16.8 M. P. Applebey and G. Ogden, J., 1936, 163.9 C. E. H. Bawn and G. Ogden, Trans. Paraday Soc., 1934, 30, 432; A.,B 21934, 60242 GENERAL AND PHYSICAL CHEMISTRY.authors 10 regard this as one of the first proofs that the leakageeffect is an important factor in the reactivities of hydrogen anddeuterium atoms, the conclusion must, for the present, be acceptedwith reserve. The high factor is based on the supposition thatnormal water contains 1 part of deuterium oxide in 5500, whereasa value of 1 to 4500 for the isotopic ratio would give a normalfactor.8 The proportion of 1 part in 9000 reported last year l1appears to be definitely excluded by the new work, and even theproportions of 1 part of D,O in 5000 or 6000 obtained from densitymeasurements l2 and by the mass spectroscope l3 may eventuallyprove to be too low : experimental work of high precision is clearlynecessary.Further experiments on the fractional distillation of water haveconfirmed the possibility of enrichment in this manner.14 Desorp-tion of electrolytic hydrogen from charcoal a t liquid-air temperaturesgives a 3- to 5-f0ld,~~ and diffusion through palladium a 4-fo1d,lGenrichment of deuterium over that originally present.Partialseparation of hydrogen and deuterium also results because of thepreferential adsorption of deuterium oxide vapour by charcoaland by silica gel.17 The claim has been made18 that, in spite ofreports to the contrary,lg in the formation of crystal hydrates thereis some selectivity in favour of deuterium oxide.Analysis.The thermal conductivity method for determiningthe deuterium content of hydrogen gas has been improvedY20 per-lo J. Horiuti and M. Polanyi, Acta Physicochimica U.R.S.S., 1935, 2, 522.11 (Mrs.) E. H. Ingold, C. K. Ingold, H. Whitaker, and R. Whytlaw-Gray, Nature, 1934, 134, 661; A., 1934, 1317.12 H. L. Johnston, J . AmeT. Chem. SOC., 1935, 57, 484; A., 590; A. J.Edwards, R. P. Bell, and J. H. Wolfenden, Nature, 1935,135, 793 ; A., 841.13 W. Bleakney and A. J. Gould, Physical Rev., 1933,44,265; A., 1933, 994.14 M. Harada and T. Titani, Bull. Chem. SOC. Japan, 1935, 10, 39, 41; A.,458; W. N. Christiansen, R. W. Crabtree, and T. H. Laby, Nature, 1935,135,870; A., 815; M. H. Wahl and H. C. Urey, J . Chem.Physics, 1935, 3, 411;A., 1064; N. Morita and T. Titani, B d l . Chem. SOC. Japan, 1935, 10, 257;A., 1087; P. Jaulmes, Chim. et Ind., 1935, 33, 1045; B., 609; see also B.Kamieriski, loc. cit., ref. (1).l5 H. S . Taylor, A. J. Gould, and W. Bleakney, Physical Rev., 1933, [ii],43, 496; A., 1934, 1316.l6 0. Luhr and L. Htzrris, ibid., 1934, [ii], 45, 843; A,, 1935, 1336.17 A. King, F. W. James, C. G. Lawson, and H. V. A. Briscoe, J., 1935,1545.1* K. Okabe, M. Harada, and T. Titani, Bull. Chem. SOC. Japan, 1934, 9,460; A., 1935,48.l9 H. Erlenmeyer and H. Gartner, Helv. Chim. Acta, 1934, 17, 970; A . ,1934, 1303; E. H. Riesenfeld and H. E. Riesenfeld, Ber., 1934, 67, [B], 1659;A . , 1934, 1327; see also Ann. Reports, 1934, 31, 89.2o H.Sachsse and K. Bratzler, 2. phyeikal. Chem., 1934, 171, 331; A.,1935, 20ULASSTONE : ISOTOPES. 43mitting of a precision of 0.02'70 with 0.5 C.C. of gas at 1 atm. Twonew methods for estimating D/H ratios, depending on the measure-ment of the freezing point of water l7 and on observations of itsvapour pressure,21 have been described.Studies of interchange reactions betweendeuterium and compounds containing hydrogen have been con-tinued, partly because of their general interest and partly in order toelucidate reaction mechanisms. Direct introduction of deuteriuminto benzene has been observed22 on shaking with 90% sulphuricacid of enhanced deuterium content : the significance of the resulthas been discussed.23 Exchange also occurs wibh methyl- anddimethyl-amineY2* as their hyckochlorides, when dissolved indeuterium-enriched water, and confirmation of the reaction betweendeuterium oxide in alkaline solution and acetylene has been claimed,25although it has been stated that exchange does not occur.26 Slowexchange takes place between sodium acetate and deuterium oxide,24and a rapid interchange between hydrogen peroxide and deuteriumoxide has been observed; 27 no reaction is noted when potassiumhypophosphite is dissolved in water containing deuterium oxide.27Water obtained from the combustion of various carbohydrates,of natural origin, has been found to contain more deuterium thannorma1.28 A number of hexoses and their glycosides, etc., havebeen observed to undergo isotopic exchange in 11-30y0 and in80-96% deuterium oxide ; the results indicate that all the hydroxylgroups take part in the exchange.29 The investigation of the directintroduction of deuterium into acetone in aqueous alkaline solutionhas been the subject of further study, and the reaction resulting inthe replacement of the fist hydrogen atom is found to be pseudo-unimolecular with a high temperature coefficient .30 Completeinterchange between deuterium and the hydrogen in the NH, groupsExchange reactions.21 0.Reitz and K. F. Bonhoeffer, 2. physikal. Chon., 1935,174, 559.22 C. K. Ingold, C. G. Raisin, and C. L. Wilson, Nature, 1934, 134, 734;23 J. Horiuti and M. Polanyi, ibid., 1934, 134, 847; A., 1935, 74; C. K.24 P. Goldfinger and V. Lasarev, Coqnpt.rend., 1936, ROO, 1671 ; A., 965.2 5 L. €I. Reyerson, J . Amer. Chem. SOC., 1935, 57, 779; A., 713; L. H.26 R. P. Bell, ibid., p. 778; A., 713.2 7 H. Erlenmeyer and H. Gartner, Zoc. cit., ref. (19).5 8 T. Titani and M. Harada, Bull. Chem. SOC. Japan, 1935, 10, 205, 261;29 W. H. Hamill and W. Freudenberg, J . Amer. Chem. Xoc., 1935, 57,30 J. 0. Halford, L. C. Anderson, J. R. Bates, and R. D. Swisher, ibid.,A., 1935, 74.Ingold, C. G. Raisin, and C. L. Wilson, ibid., p. 847; A., 1935, 74.Reyerson and B. Gillespie, ibid., p. 2250.A., 944, 1212.1427 ; A., 1212.p. 166344 GENERAL AND PHYSICAL CHEMISTRY.of metal ammines occurs when the latter are dissolved in watercontaining deuterium 0xide.~1 Atomic deuterium enters into ex-change reactions with water vapour, ammonia, and acetylene, butnot with methane,32 contrary to results previously reported.33Catalytic exchange reactions between D, and H,O and betweenH, and D,O on the surfaces of chromium sesquioxide, zinc oxide andchromite, alumina and platinised asbestos have been observed : thevariation of the former reaction velocity with temperature on thefirst catalyst has been determined approximately and the mechanismhas been discussed?* Methane exchanges35 with deuterium on anickel catalyst at 184-305", and ammonia similarly reacts withdeuterium on a Pe-Al2O3-K,O catalyst at room temperature ; 36 thebearing of the latter observation on the kinetics of the ammoniasynthesis is discussed.Benzene and deuterium oxide exchangereadily at 200" on nickel-kieselguhr, the product consisting of anequilibrium mixture of various deuterobenzenes 37 (see also p.48).A serious source of error in exchange experiments has been indicatedas being caused by hydrogen remaining adsorbed on quairtz vesselsand platinum wires even when apparently thoroughly o~t-gassed.~sThe melting points of hydrogen and deuterium havebeen determined as 13.95" and 18-59' Abs., respectively, and thecorresponding heats of fusion are 28.0 and 47.0 g.-cals. The charac-teristic (Debye) temperatures, for Cp, of the solids are 91" and 89",respectively.39 The heats of evaporation 4O of liquid hydrogen anddeuterium a t 19-65' Abs., and the vapour pressures of o- and p -deuterium a t 20.38" Abs., of o- and p-hydrogen at 17-13' Abs.,41and of n- and e-deuterium over the range 15-20-4" A ~ S .~ ~ havebeen measured. Differences in the properties of hydrogen and31 H. Erlenmeyer and H. Glirtner, Helv. Chim. Acta, 1934, 17, 1008; A.,1934, 1321; H. Erlenmeyer and H. Lobeck, ibid., 1935,18,1213; A., 1332.32 K. H. Geib and E. W. R. Steacie, 2. phy8ikal. Chem., 1935,29, [B], 215;9., 1087.33 H. S. Taylor, K. Morikawa, and W. S. Benedict, J . Ainer. C'hem. SOC.,1935, 57, 383; A., 457.34 H. S. Taylor and H. Diamond, ibid., p. 1256; A., 1086.35 H. S. Taylor et al., loc. cit., ref. (33).36 H. S. Taylor and J. C. Jungers, ibid., p. 660; A., 710; see also K. Wirtz,37 P. I. Bowman, W. S. Benedict, and H. S. Taylor, J . Amer. Chem. SOC.,38 A. Farkas and L. Farkas, Trans.FaracEay SOC., 1935,31, 821 ; A., 710.39 K. Clusius and E. Bartholom6, Physikal. Z., 1934, 35, 969; A., 1935,40 Idem, Z. physikal. Chem., 1935, [B], 30, 237.dl K. Clusius, ibid., 1935, [B], 29, 169; A., 925.42 F. G. Briokwedde ,R. B. Scott, and H. S. Taylor, J . Chem. Physics, 1935,Properties.2. physikal. Chem., 1935, [B], 30, 289.1935,57,960 ; A., 852.155.3, 653GLASST'ONE : ISOTOPES. 45deuterium are attributed partly to differences in zero-point energiesand partly to other fa~tors.~O The heat capacities43 of o- andn-deuterium have been determined and the entropy of n-deuteriumat 298.1" Abs. evaluated: 44 the result is compared with thatcalculated from spectroscopic data by the statistical method, andthe difference in the two values explained by the persistence ofrotation in the solid state (cf.p. 88). The thermal conductivity,45volume coefficient of expansion,46 molecular viscosity,47"and rates of diffusion of deuterium gas through palladium 48 andcopper 49 have been studied, and the results compared with thosefor hydrogen gas. The difference in adsorption of hydrogen anddeuterium on various surfaces has been investigated from boththeoretical 5O and practical standpoints; 51 one of the applicationsof the latter is in connexion wit,h the reaction with ethylene.52The ratio of the magnetic moment of the proton to that of thedeuteron has been determined at 83", 193", and 293" Abs. by themethod based on the rates of the paramagnetic ortho-para conversionof hydrogen and deuterium.53 Provisional mass-spectrographicvalues for the atomic weights of the two isotopes, based on OL6, havebeen published; accurate results are desirable, as they may help inthe estimation of the deuterium oxide content of normal water.54Deuterium oxide.The value of for pure deuterium oxide isnow reported 55 as 1.1071, which is lower than that previously43 K. Clusius and E. BartholomB, Naclz. Ges. Wiss. Gottingen, M&.-phys.44 Idem, ibid., 1935, [B], 30, 237.45 A. B. van Cleave and 0. Maass, Cnnadian J . Res., 1935,12,372; A., 691.4 6 J. B. M. Coppock, Tram. Paraday SOC., 1935, 31, 913; A., 1064.4 7 A. B. van Cleave and 0. Maass, Cunadian J . Res., 1935, 12, 57; A . , 432.4 7 ~ I. Amdur, J. Amer. Chem. SOC., 1935, 57, 588.48 W.Jost and A. Wid.mann, 2. physikal. Chem., 1935, [B], 29, 247; A.,1200; H. W. Melville and E. K. Rideal, Proc. Roy. Xoc., 1935, [A], 153, 89;0. Luhr and L. Harris, loc. cit., ref. (16); se0 also A. Sieverts and G. Zapf,2. physikal. Chem., 1935,174,559.Kl., 1934, [C], 1, 1 ; 2. physikal. Chem., 1935, [B], 29, 162; A., 573, 924.413 H. W. Melville and E. K. Rideal, Zoc. cit., ref. (48).50 J. E. Lennard-Jones and C. Strachan, Proc. Roy. SOC., 1935, [ A ] , 150,442, 456; A., 1070.61 J. Pace and H. S. Taylor, J. Chem. Physics, 1934, 2, 578; A., 1934,1181; R. Klar, Naturwiss., 1934, 22, 832; A., 1935, 27; H. W. Kohlschiitter,2. physikal. Chem., 1934, 1'70, 300; A., 1935, 27; R. Kler, ibid., 1935, 174,1 ; A., 1329; H. W. Melville and E. K.Rideal, Proc. Roy. SOG., 1935, [A],153, 77.52 R. Klar, loc. cit.; 2. physikal. Chem., 1934, [B], 27, 319; A., 1935, 175.53 L. Farkas and A. Farkas, Nature, 1935,135, 372; A , , 560.54 F. W. Aston, ibid., 1935,135, 541 ; A., 677.55 L. Tronstad, J. Nordhagen, and J. Brun, ibid., 1936, 136, 515; A.,131346 GENERAL AND PHYSICAL CHEMISTRY.accepted,56 the difference being probably due to the larger 0l8content : for water containing less than 1 part of deuterium oxide in2 x lo5, dii: is 0.9999815. Measurements have been made of theheat capacities 57 of liquid and solid deuterium oxide, of the heatsof fusion 5 7 5 58 and melting points of mixtures 59 of light and heavyice, of the heats of vaporisation and dilution,60 and of the vapourpressures 61 of mixtures of liquid water and deuterium oxide.Thegeneral P- V-T relationships of solid and liquid deuterium oxidehave been studied,62 and different forms of heavy ice identified.The differences in the thermal properties of water and deuteriumoxide cannot be accounted for by their zero-point energies only;the importance of angular vibration or " libration " of the moleculeshas also been ons side red.^^ Observations have also been describedof the refractive index,G4 dielectric constant,65 surface tension,66and critical temperature 67 of liquid deuterium oxide, of its diffusionin ordinary water,68 of the diamagnetism G9 of the liquid and solidstates, and of the cell-dimensions 70 of solid deuterium oxide.The ratio of the dissociation constants '1 of deuterium oxide andwater is said to be 0.16 to 1 at 2loY from measurements with cells56 H.S. Taylor and P. W. Selwood, J . Amer. Chem. SOC., 1934, 56, 998;A., 1934, 590; see also, ibid., 1935, 57, 642, footnote (4).5 7 R. S. Brown, W. H. Barnes, and 0. Maass, Canadian J . Res., 1935, 12,699; A., 1198; E. Bartholome and K. Clusius, Z. physikal. Chem., 1935,[B], 28, 167; A., 584.58 L. Jacobs, Trans. Paraday Soc., 1935, 31, 813; A., 704.5D V. K. LaMer and W. N. Baker, J . Amer. Chern. Soc., 1934, 56, 2641;A., 1935, 167.6o E. Doehlemann and E. Lange, 2. physikal. Chem., 1935, 178, 295 ; A.,935.61 W. F. K. Wynne-Jones, J . Ghem. Physics, 1935,3, 197; A., 694; M. H.Wahl and 13. C. Urey, Zoc. cit., ref. (14).62 G. Tammann and G.Bandel, 2. anorg. Chern., 1935, 221, 391 ; A., 302 ;J. Timmermans and L. Deffet, Compt. rend., 1935,200,1661; A., 815; P. W.Bridgman, J . Chem. Physics, 1935,3,897 ; A., 1454.63 J. D. Bernal and G. Tamm, Nature, 1935, 135, 229; A., 432; P. W.Bridgman, 106. cit., ref. (62).64 W. J. C. Orr, ibid., p. 793; A., 810.*5 P. Abadie and G. Champetier, Compt. rend., 1935, 200, 1590; A., 808.66 I. Minkow, Nature, 1935, 136, 186; A., 1059.67 E. H. Riesenfeld and T. L. Chang, 2. physikal. Chern., 1935, [B], 28,408; 30,61; A., 691.6 8 W. J. C. Orr and D. W. Thomson, Nature, 1934,134, 776; A,, 1935,25;M. Temkin, ibid., 1935,136, 552; A., 1313; W. J. C. Orr and J. A. V. Butler,J., 1935, 1273; A., 1313.69 F. W. Gray and J. H. Cruickshank, Nature, 1935, 135, 268; A., 435;B.Cabrera and H. Fahlenbrach, Anal. Pis. Quirn., 1934,32,538 ; A ., 1935,923.70 H. D. Megaw, Nature, 1934, 134, 900; A., 1935, 151.71 E. Abel, E. Bratu, and 0. Redlich, 2. physikal. Chem., 1935, 173, 353;cf. Ann. Reports, 1934, 31, 17GLASSTONE : ISOTOPES. 47involving deuterium electrodes in deuterium chloride and sodiumdeuteroxide solutions. The dipole moment of the deuterium oxidemolecule, measured either in the vapour state 72 or in solution inbenzene 73 or d i ~ x a n , ~ ~ is not more than 0.02 x PO-18 e.s.u. greaterthan for water, although a somewhat larger difference might havebeen expected the~retically.~~ A similar difference of 0.03 x 10-18e.s.u. exists between the dipole moments of ammonia and trideuter-ammonia.75 Freezing-point determinations of solutions of waterand of deuterium oxide in dioxan indicate that the latter is slightlymore associated in this solvent,76 and a similar conclusion is derivedfrom the difference in the heat capacities of the liq~ids.~7 Replace-ment of H,O by D,O in binary systems with organic compounds,e.g., phenol, acetonitrile, triethylamine, and propionic acid, raisesthe upper and depresses the lower consolute temperat~res.7~Deuterium compounds.The absorption spectra of the bromides 79and iodides *O of hydrogen and deuterium have been studied, and thereason for the differences considered. The vapour pressures andboiling points 79 (206.3" Abs.) of the two bromides are identical,but the vapour pressure of deuterium iodide is slightly greaterthan that of hydrogen iodide, and the boiling point of the former(237.0" Abs.) is consequently 0.5" lower. The higher vapourpressure of the deuterium compound is probably due to factorsdifferent from those which result in its fluoride having a highervapour pressure than that of hydrogen.According to an approxim-ate theoretical treatment,s1 the vapour-pressure curves of thecorresponding hydrogen and deuterium compounds should crossat some temperature: this is apparently often above the boilingpoint, and so the conditions under which the latter have the highervapour pressure are not often observable. The transition pointof sodium sulphate decadeuterate (Na,SO,,lOD,O) is 34-48'. 82Pure hexadeuterobenzene 83 has been obtained by distilling the72 L.G. Groves and S. Sugden, J., 1935, 971.73 F. H. Muller, Physikal. Z., 1934, 35, 1009; A., 1935, 148.74 R. P. Bell, Trans. Paraday Soc., 1935, 31, 1345; A., 1304.75 J. M. A. de Bruyne and C. P. Smyth, J . Amer. Chem. Soc., 1935, 57,76 R. P. Bell and J. H. Wolfenden, J., 1935, 822; A., 931.7' R. S. Brown, W. H. Barnes, and 0. Maass, Zoc. cit., ref. (57).78 J. Tirnmermans and G. Poppe, Compt. rend., 1935, 201, 524; A., 1314.7g J. R. Bates, J. 0. Halford, and L. C. Anderson, J . Chem. Physics, 1935,80 Idem, ibid., p. 415; A., 1064.81 H . C. Urey and G. K. Teal, Zoc. cit., ref. (4), p. 58.82 H. S. Taylor, J . Amer. Chem. SOC., 1934, 56, 2643; A., 1935, 447.88 H. Erlenmeyer and H. Lobeck, Helv. Ohirn. Acta, 1935, 18, 1464; A.1203 ; A., 1055.3,531 ; A., 1313.Klit and A.Langseth, Nature, 1935, 3135, 956 ; A., 80648 GENERAL ABD PHYSICAL CHEMISTRY.calcium salt of mellitic acid with calcium deuteroxide and also byappIying the Friedel-Crafts reaction to benzene and deuteriumchloride : it has f . p. + 6.8" and b. p. 79.4", the corresponding valuesfor benzene being + 5.5" and + 80.12". These results agree withsome previously published,84 but differ markedly from others inwhich the hexadeuterobenzene was made by passing dideuter-acetylene over a tellurium cataly~t.8~ Octadeuteronaphthalene issaid to be obtained as a by-product in the latter process.86 Theexchange between benzene and deuterium oxide on a nickel-kieselguhr catalyst, already mentioned (p. 44), has been used toprepare hexadeuterobenzene ; if the mixed benzenes are separatedafter equilibrium is attained, and re-heated with pure deuteriumoxide, it is claimed that hexadeuterobenzene of over 99% purity, d;?0-9417, can be obtained after four operation^.^^ Dideuteromalonicdeuteracid, CD2( CO,D),, results from the action of deuterium oxideon carbon suboxide ; on heating to 140-150°, trideuteraceticdeuteracid, CD,-C02D, 112.p. 15.75", is obtained. The latter sub-stance is more volatile than acetic acid.87 Catalytic reduction oflinoleic acid with deuterium yields 6 : 7 : 9 : 10-tetradeuterostearicacid,88 and the addition of deuterium to cholestenone gives 4 : 6-dideuterocopro~tanone,~~ which has been used as an " indicator "in biological experiments.Solutions in heavy water.The conductivities of potassiumchloride and of deuterium chloride in deuterium oxide are 17%and 2S%, respectively, less than the corresponding values in water ;the differences are chiefly due to a 23% increase in the viscosity ofthe solvent. Similar decreases in the conductivities of hydrochloricand perchloric acids in deuterium oxide solution have been noted.91The conductances of mixtures of the chlorides of hydrogen anddeuterium are less than the expected values : the discrepancy can beexplained by supposing that hydrogen and deuterium ions take partin Grotthuss conducti~n.~~ The ratio of the dissociation constantsof a weak acid in water and in deuterium oxide should be largerthe weaker the acid.92 The free energy of hydration of the hydrogenion is stated to be greater in deuterium oxide than in water; a84 C.L. Wilson, Nature, 1935, 136, 301; A., 1198.8 6 G. R. Clem0 and A. McQuillen, J., 1935, 881; A., 967.* 6 I d e m , ibid., p. 1325; A., 1358.8 7 C. L. Wilson, ibid., p. 492; A., 731.8 8 R. Schonhoimer and D. Rittenberg, J . Bid. Chem., 1935, 111, 163; A.,89 R. Schonheimer, D. Rittenberg, and M. Graff, ibid., p. 183; A., 1407.91 A. Fink, P. Gross, and H. Steher, Monatsh., 1935, 66, 111 ; A., 1324.92 0. Malpern, J . Chem. Physics, 1935, 3, 456; A., 1203.1407.W. N. Baker and V K. LaMer, J . Chem. Physics, 1935,3,406; A., 1078GLASSTONE : ISOTOPES. 49similar difference is supposed to exist for hydrogen- and deutero-a~ids.9~ The potential of the quinhydrone electrode in 0-001M-hydrochloric acid in deuterium oxide has been found to be 0.0345volt more positive than in water; the ratio of the products of thetwo dissociation constants in water to that in deuterium oxideis 3.84.94 The cathodic overvoltage a t mercury is greater for theliberation of deuterium than of hydrogen, as is to be expected;the temperature coefficient is greater for the former.95 Observationshave also been made with the dropping-mercury cathode in varioussolutions containing deuterium oxide.g6Kinetics, etc.The spectroscopy, reaction kinetics, and surfacechemistry of deuterium compounds are mainly treated elsewhere inthese Reports : mention may be made in addition of the followingtopics. Two papersg7 dealing with the application of quantummechanics to reactions involving hydrogen and deuterium haveappeared, and a review article 98 on the use of the latter in the studyof acid-base catalysis has been published.The catalytic decomposi-tions of nitroamine by hydrochloric acid 99 and of hydrogen peroxideby the iodide ion are slower in deuterium oxide than in water,although for the latter reaction the energies of activation are thesame for both media in spite of the differences in the zero-pointenergies of hydrogen peroxide and deuterium peroxide. Thecatalysis of H20 and D, exchange by enzymes has been investigated ;the enzymic fission of salicin by emulsin is 25% more rapid indeuterium oxide than in water.3 The photo-oxidation of the iodidesof hydrogen and deuterium shows that the reactions between H orThe rate of the mercury-photosensj tised decomposition of acetyleneis about 30% greater than for dide~teracetylene,~ and a similar93 P.Goldfinger and W. Jeunehomme, CYompt. rend., 1935, 200, 1387; A.,824.94 V. K. LaMer and S. Korman, J . Amer. Chem. SOC., 1935, 57, 1511; A.,1205.95 F. P. Bowden and H. F. Kenyon, Nature, 1935, 135, 105; A., 450.96 J. Heyrovskf and 0. H. Miiller, Coll. Czech. Chem. Comm., 1935, 7,97 R. A. Smith, Proc. Camb. Phil. Soo., 1934, 30, 508; A., 1935, 306; R. P.98 W. F. K. Wynne-Jones, Chem. Reviews, 1935, 17, 115.99 C. A. Marlies and V. K. LaMer, J . Amer. Chem. SOC., 1935, 57, 1812; A.,E. Abel, 0. Redlich, and W. Stricks, Monatsh., 1936, 65, 380; A., 939.3 G.33.. Bottomley, B. Cavanagh, and M. Polanyi, Nature, 1935, 136, 103 ;3 E. W. R. Steacie, 2. physikal. Chem., 1935, [B], 28, 236; A., 588.4 G. A. Cook and J. R. Bates, J . Amer. Chem. SOC., 1935, 57, 1775.J. C. Jungers and H. S. Taylor, J . Chem. Physics, 1935, 3, 338; A . , 943.D and oxygen are three-body processes, and kH+OI+OI N kD+ol+02. 4281; A., 1079; 0. H. Miiller, ibid., p. 321; A., 1208.Bell, Proc. Roy. SOC., 1935, [A], 148, 241; A., 560.1466.A., 108460 GENERAL AND PHYSICAL CHEMISTRY.difference is observed in the combination of oxygen with hydrogenor deuterium in the presence of a-particles.6 The rate of polymeris-ation of dideuteracetylene under the influence of a-particles is,however, the same as for acetylene.’ The decomposition of trideuter-ammonia, like that of ammonia, on a tungsten filament is approxim-ately of zero order, although the former reaction is the slower.*A comparison has been made of the rates of ortho-para hydrogenconversion and of the H, + D, = 2HD reaction on a nickel catalyst :the mechanism of both processes is evidently the same.gGraphical arrangements of the knownisotopes of elements of low atomic weight indicated the possibilityof the existence of an isotope of hydrogen of mass 3, now called“tritium ” and given the symbol T.It was claimed lo that thepresence of tritium oxide in water containing 2% of deuterium oxidecould be detected by the magneto-optic method, but band-spectro-scopic examination 11 showed that the upper limit of its concentra-tion was 6 parts in 106 of ordinary hydrogen ; by the aid of the mass-spectrograph l2 this limit was placed at 2 parts in 109 as a maximum.Working with 99% deuterium oxide, G.Hertz has definitely provedthe presence of tritium by its mass-spectrogram; 13 the T : D ratiowas 5 : lo6, indicating a proportion of 1 part, or less, of tritium inlo9 of natural hydrogen. Study of the impacts of high-speeddeuterons on deuterium nuclei had indicated the occurrence ofthe disintegration l4 D + D ---+ H + T, and the passage of apositive-ray discharge through deuterium is stated l5 to result in anincrease of the T/D ratio from 1/200,000 to l/S000 : the absoluteamount of tritium formed must, however, be very small. In spiteof the apparent hopelessness of the task, 75 metric tons of waterhave been electrolysed down to 0-5 c.c.,16 which was found to contain1 part of tritium oxide in 4000 : the abundance of tritium in ordinarywater is estimated as 7 parts in 1W0.Under the experimentalOther Isotopes.-Tritium.S. C. Lind and C. H. Schiflott, J . Amer. Chem. Soc., 1935, 57, 1051; A.,7 S . C. Lind, J. C. Jungers, and C. H. Schiflett, ibid., p. 1032; A., 943.944.J. C. Jungers and H. S. Taylor, ibid., p. 679; A., 710.E. Fajans, 2. physikal. Chern., 1935, [B], 28, 239; A., 710.W. M. Latimer and Ip. A. Young, Physical Rev., 1933,44, 690.l1 G. N. Lewis and F. H. Spedding, ibid., 1933,43,964.l2 W. Bleakney and A. J. Gould, ibid., 1934, 45, 281.xi W. W. Lozier, P. T. Smith, and W.Bleakney, ibid., p. 655; M. A. Tuve,14 Ann. Reports, 1934, 31,387.16 G. P. Harnwell, H. D. Smyth, S. N. van Voorhis, and J. B. H. Kuper,16 P. W. Selwood, H. S. Taylor, W. W. Lpzier, and W. Bleakney, J. Arner.L. R. Hafstad, and 0. Dahl, ibid., pp. 746, 840.Physical Rev., 1934, 45, 655.Chem. Soc., 1935,57, 780; A., 711GLASSTONE : ISOTOPES. 51conditions, apparently nickel electrodes in alkali, the Dz--T2 separationcoefficient is 2.0, in agreement with theoretical predictions.17 Itappears probable that small quantities of water enriched with tritiumwill soon be available for experimental work.Oxygen and Nitrogen Isotopes.-W ater containing 018 in excess ofthe normal has been obtained by a diffusion method,18 and a slightenrichment has been observed in oxygen obtained from liquid airby the fractionation process; l9 the difference 2O of 1.4% in thevapour pressures of H,016 and H,Ols has resulted in a partialseparation by the fractional distil1at)ion of water.21 Decompositionof 30% hydrogen peroxide by colloidal platinum yields a gas with a0l6/Ol8 ratio of 462 & 8, compared with 426 & 4 for the residue.22Conflicting reports on the ehticiency of electrolysis in bringing abouta concentration of 018 have been published: in early work noenrichment was observed,23 but the reason for this is now apparent(see below).More recently the concentration of 0 1 8 in the residualwater has been e~tablished,~~ although the separation factor appearsgenerally to be no more than 1.01 : the reduction of the volume ofwater 100,000-fold by electrolysis increases the 0l8 content ofordinary oxygen from 0.20 to only 0.22y0.25 A separation coefficientof 1.15 has been reported recently 26 for the electrolysis of 1.25N-sodium hydroxide with nickel electrodes, although a previous claim 27for a coefficient of the same order has now been revised 28 bo 1.05.Assuming the rate-determining step in the separation of 0, byelectrolysis is the passage of a O1*H or OleH complex over or throughl7 H.Eyring, quoted in ref. (16).la 2. P h p i k , 1932,79,108; see M. Polanyi and A. S. Szabo, Tram, ParadaySOC., 1934, 30, 508; A., 1934, 979.lS R. Klar and A. Krauss, Naturwiss., 1934,22,119; A., 1934, 377; E. R.Smith, J . Chern. Physics, 1934, 2,298; A., 1934, 855.2o M.H. Wahl and H. C. Urey, ibitl., 1935,3, 41 1.21 G. N. Lewis and R. E. Cornish, J . Arner. Chem. SOC., 1933, 55, 2616;22 H. S . Taylor and A. J. Gould, ibid., 1934, 56, 1823; A., 1934, 1082.23 G. N. Lewis and R. T. Macdonald, J . Chem. Physics, 1933, 1, 341 ; A..1934, 10; P. W. Selwood and A. A. Frost, J . Arner. Chem. SOC., 1933, 55,4335; A., 1933, 1233; W. Bleakney and A. J. Gould, Zoc. cit., ref. (12).24 E. W. Washburn, E. R. Smith, and M. Frandsen, J . Res. Nat. Bur.Stand., 1933, 11, 453; A., 1934, 156; E. W. Washburn, E. R. Smith, andF. A. Smith, ibid., 1934, 13, 599; A., 1935, 175; C. H. Greene and R. J.Voskuyl, J . Arner. Chem. SOC., 1934, 56, 1649; H. L. Johnston, ibid., 1035,57,484; A., 590; W. H. Hall and H. L.Johnston, ibid., p. 1515; A., 1330.26 P. W. Selwood, a. S . Taylor, J. A. Hipple, and W. Bleakney, ibid.,p. 642; A., 711.26 G. Ogden, Nature, 1935, 136, 912.27 E. W. Washburn, E. R. Smith, and F. A. Smith, Zoc. cit., ref. (24).28 E. R. Smith and M. Wojciechowski, J . Res. Nat. Bur. Stmd., 1935, 15,G. N. Lewis, ibid., p. 3502.187 ; A., 132952 GENERAL AND PHYSICaL CHEMISTRY'.an energy barrier, a separation coefficient of 1-1-16 can be cal-culated,26 according to the width and height of the barrier. Themost favourable value would lead only to a four-fold increase inconcentration of 0l8, whilst the deuterium concentration in waterwas raised from 1 in 5000 to 100%. Such an enrichment wouldprovide a, tool of value to chemists, but it is doubtful if even thisrelatively low efficiency could be attained, especially as an alternative,approximate, calculation indicates a probable factor of 1.06 for theratio of the rates of separation of Oi6 and Oi8 on ele~trolysis.~~Calculations by statistical methods 29 (p.70) of the equilibriumconstant of the exchange reaction 2H,018 (E) + Oi6 = 2H2016 (I) +Oi8 gives a value of 1.012, implying an enrichment factor of 1.006at 25' : this equilibrium, which opposes the normal electrolyticseparation, will tend to be attained in the evolution of oxygen,and may explain the different electrolytic separation coefficientsreported by different workers.25 The equilibrium constant of thereaction 2H2018 (Z) + COP = 2H2W ( I ) + C0i8 has been calc~lated,~gand the result shows that the carbon dioxide gas should alwayscontain a larger proportion of 0l8 than does the water : the theoreti-cal fractionation factor, i.e., the ratio 0 1 8 / 0 1 6 in the gas to that) inthe water, of 1.047 at 0" has been confirmed e~perimentally.~~A counter-current process, based on the establishment of theequilibrium, for obtaining carbon dioxide enriched with 0l8, hasbeen devised 29 and is being tested.It is the use of carbon dioxidefor the neutralisation of the alkali that had become concentratedon electrolysis, which was probably responsible for the failure todetect any change of 0 1 8 in the early work mentioned above.s2, 25An attempt has been made to concentrate N15 by the fractionaldistillation of liquid ammonia : the results so far are not veryencouraging, but they indicate that the method may be of some usefor increasing the N15/N14 ratio.31Art~~cially-rudiouctive Isotopes.-Mention may be made of theuse of these substances as indicators in chemical investigations.By taking advantage of the radioactivity induced in bromine byneutron bombardment, it has been shown that the bromide ionin sodium bromide undergoes exchange with elementary bromine inaqueous solution.32 Iodine and sodium iodide exchange readilyin a similar manner, as also does iodine with methyl and ally12g H.C. Urey and L. J. Greiff, J. Amer. Chem. SOC., 1935,57, 321 ; A., 446.3O L. A. Webster, M. H. Wahl, and H. C. Urey, J. Chern. Physics, 1935,81 M. H. Wahl, J. F. Huffman, and J.A. Ripple, J. C'hent. Physics, 1936,12 A. von Grosse and M. S. Aquss, J, Amer. Chcnt. Xoc., 1935,57, 591 ; A.,8, 129; A., 693; see also M. P. Applebey and G. Ogden, J., 1936, 163.3,434.595SUTHERLAND : SPECTROSCOPY. 53iodides ; ethyl, n-propyl, isopropyl, and methylene iodides andiodoform, however, exchange very slowly, if at all.33 Only theiodide ion of diphenyliodonium iodide undergoes exchange withiodine; the experimental results are used to throw light on themechanism of the decomposition of the iodide in iodobenzenesolution.34 The rate of exchange of elementary iodine with theiodine in sec.-octyl iodide is equal to the rate of racemisation of thed-iodide : 35 the significance of this result is discussed elsewhere inthese Reports (p.96). A start has also been made in what islikely to be an important development, namely, the use of theradioactive isotope P32 in the study of metabolic processes.36S. G.3. SPECTROSCOPY.Atomic Xpectra and the Spectra of Diatomic Molecules.--In neitherof these fields are there any striking advances to report. This isto be expected, since the fundamental and important steps in eachwere made several years ago, and all that remains is to fill in thegaps in our knowledge of the energy levels of the less common atomsand molecules. The results for atomic states have been tabulatedin a book by R. F. Bacher and S. G0udsrnit.l Recently, interesthas shifted towards the determination of nuclear magnetic momentsfrom the investigation of the hyperfine structure of Bpectral lines.This has already been dealt with in last year’s Reports and neednot be repeated here, especially since it is only of secondary interestto chemists.The corresponding collection of results regardingthe energy levels and electronic structure of diatomic moleculeshas just appeared in an excellent compilation by Frl. H. Sponer(see p. 39). For more general treatment, reference should be madeto earlier Reports3 or to the books of R. de L. Kronig4 and ofW. Jevons and to the reports of R. S. Mulliken.6Spectra of Polyatomic Molecules.-It is here that the most interest-ing advances have been made from the chemical standpoint. Instead33 F. Juliusburger, B. Topley, and J. Weiss, J. Chent. Physics, 1935, 3,437.34 Idem, J., 1935, 1295.35 E.D. Hughes, F. Juliusburger, S. Masterman, B. Topley, and J. Weiss,35 0. Chiewitz and G. von Hevesy, Nature, 1935, 136, 754.ibid., p. 1525.“ Atomic Energy States,” McGraw-Hill, 1933.Ann. Reports, 1934, 31, 372.“ The Optical Basis of the Theory of Valency,” Cambridge, 1935 ; “ Band“ Report on the Spectra of Diatomic Molecules,” Cambridge, 1932.Rev. Mod. Physic&?, 1930, 2, 60; 1931, 3, 89; 1932, 4, 1.a Ibid., 1933, 30, 68.Spectra and Molecular Structure,” Cambridge, 193054 GENERAL AXD PHYSI(xBL( UHlWISTRY.of giving detailed results, it would appear more valuable, however,to take stock of what has been done during the past few years,reviewing the principles and methods by which it has been accom-plished,’ in order that limitations on future progress may be clearlyrealised. The polyatomic molecule may best be approached byconsidering what it has in common with, and wherein it differs from,the diatomic molecule.Just as the energy of a diatomic moleculemay be divided into three (practically independent) parts, vix.,electronic, vibrational, and rotational, so may that of a polyatomicmolecule, and consequently the latter has three distinct spectra :a pure rotation, a vibration-rotation, and an electronic spectrum.The differences between a diatomic and a polyatomic moleculebecome evident as soon as we consider the structure of any one ofthese three types. This follows since the expression for the energyof a polyatomic molecule is considerably more complicated than thatfor a diatomic molecule, as well as the selection rules governing itsallowed changes.For example, a diatomic molecule has effectivelyonly one moment of inertia, whereas the general polyatomic moleculehas three different moments of inertia; the expression for therotational energy in the first case is consequently very simple,while in the second case no explicit expression exists for the energylevels, although these can be computed. Again, the diatomicmolecule has only one degree of vibrational freedom, or one funda-mental vibration frequency, whereas the polyatomic molecule ofn atoms has, in general, 3n - 6 fundamental frequencies with aset of selection rules governing the appearance of each in the differenttypes of spectra. Finally, the electronic energy states of a diatomicmolecule are usually characterised by the associated resultantangular momentum about the internuclear axis, whereas in apolyatomic molecule these have to be specified through the symmetryand transformation properties of the associated wave functions.Nevertheless, the apparently hopeless complexity which such factorsintroduce into the spectra of polyatomic molecules has proved to bemore capable of disentanglement than one would have at firstsupposed.Before passing to the consideration of the three main classes ofspectra, it should be mentioned that these are all normally observedin absorption.In the case of the first two, however, they may alsobe obtained by scattering (Raman although the selectionD. M.Dennison, Rev. Mod. Physics, 1931, 3, 280. Articles by R. Mecke,E. Teller, and 0. Reinkober in the ‘‘Hand- und Jahrbuch der ChemischenPhysik,” 1934, Band 9/11; G. B. B. M. Sutherland, “ Infra-Red and RamanSpectra,” Methuen, 1935.8 Ann. Reporto, 1934,31, 21SUTHERLAND : SPECTROSCOPY. 55rules differ from those operative in absorption, and we shall have toconsider the relation between them more fully in what follows.A. Pure rotation spectra. For convenience in this and other sec-tions, we shall immediately divide polyatomic molecules into fourclasses according to their degree of rotational symmetry. If thethree moments of inertia are denoted by I*, IB, Ic, then thereare four classes of molecules : (1) linear molecules, for whichla = IB, I.= 0; (2) spherical molecu{les, for which la = IB = I c ;(3) symmetrical top molecules, for which IA = Ig I,; and (4)asymmetrical top molecules, for which IA I IB Io. The corre-sponding energy expressions and selection rules have been collectedin Table I. By examination of this table and application of theappropriate selection rule, it is clear that the pure rotation spectrumof a linear polyatomic molecule is in no way different from that of adiatomic molecule. Next, we note that spherically symmetricalmolecules (such as methane, carbon tetrachloride, etc.) have nopure rotation spectra. The absorption spectrum of a symmetricaltop molecule is exactly like that of a diatomic molecule with amoment of inertia equal to that of the symmetrical top moleculeperpendicular to its axis of symmetry.Thus, the spacing of thelines in the pure rotation spectrum of a symmetrical top moleculeTABLE I.Rotational Energy Formulce and Selection Rules for the Four Classesof Polyatomic Molecules.Selection rules. - ( a ) ( b )Class of Expression for Infra-red Ramanmolecule. rotational energy, &',., spectra. spectra .19S,elAJ(J+l)J = O , 1, 2, . I . AJ=&,1 AJ=O, f 2h*Spherical snaI, J( J + 1 1 No active No activeI* = I B = I0 J=O, 1, 2, . . . transitions transitionsh2 J ( J + 1 ) + --A K2h2IA=IB + I c K<J; J = O , l , . . . AK=O AK=OSymmetrical top (:c la) 8a2 A J = & l A J = O , + l , & 2No simple explicit expressionAsymmetrical top in terms of J , the quantum A J = f l A J = O , & l , f 2.la =+ IB I 10 number for total angularmomentum.can yield no information regarding the moment of inertia about thesymmetry axis (for AK = 0 in the Raman spectrum too).TheRaman spectrum is slightly more complicated, containing an 0 and anX branch in addition to the usual P , &, and R ones. Although th56 GENERAL AND PHYSICAL CHEMISTRY.spacing of the lines is independent of Ic, the intensity of the linesis a function of Io/Ia, and it is interesting to note that it has beenpossible in this way to confirm the flat pyramidal model of theammonia molecule by a careful intensity measurement of its purerotation Raman spe~trum.~Theenergy levels are characterised by the quantum number J of thetotal angular momentum.Corresponding to each value of J(1, 2, 3 . . .) there are 2J + 1 sub-levels, the values of whieh maybe computed by solving certain algebraic equations. As some ofthese equations will only admit of numerical (approximate) solution,it means that the moment of inertia must be known in order to makethe computation. Usually a fair approximation to the values ofthe moments can be made from other evidence : the levels may thenbe computed and the agreement with observation tested. By aprocess of successive approximation, one finally arrives a t valuesfor the moment which give agreement with experiment. Such aprocedure is extremely laborious and requires very accurate ex-perimental data before it can be applied. In fact, no asymmetricaltop molecule has had its pure rotation spectrum analysed in thisidealised way, although for the H,O molecule R. Mecke has shownthat all of the known lines may be classified by treating the asym-metrical rotator as an imperfect symmetrical rotator.1°When one considers the experimental difficulties in obtaining thistype of spectrum (under high resolution), it does not seem probablethat it will ever become an important source of information for thestructure of molecules.All of the information derivable can beobtained from vibration rotation or from electronic spectra, both ofwhich are very much easier to observe. The only advantage of purerotation spectra is their comparative simplicity, but as spectro-scopists become more experienced this will not count for very much,since the degree of resolution of lines obtainable in the near infra-red and the visible region is a t present as high as or higher than thatobtainable a t longer wave-lengths.B. Vibration-rotation spectra.This is the class of spectra whichhas so far proved most productive of information about polyatomicniolecules. Such spectra are not so complex as electronic, and yetyield just as much information as the latter do regarding the groundstate of the molecule. Their investigation is almost a necessarypreliminary to the study of electronic spectra, and certainly aninvaluable concomitant. From their analysis, we can obtain thevalues of the fundamental vibration frequencies, the shape of thelo " Hand- und Jahrbuch der Chemischen Physik," 1934, Band 9/11.The asymmetrical top molecule presents serious difficulties.C.M. Lewis and W. V. Houston, Physical Rev., 1933, 44, 903SUTHERLAND : SPEU"E0SCOPY. 57molecule, its moments of inertia, and (in certain cases) the inter-nuclear distances.would not be of interest here, nor would the cataloguing of resultsfor a, large number of molecules. Such information is more con-veniently available elsewhere.lOa What is important is to realise thegeneral principles underlying these analyses, and to be able toestimate the limitations of such a mcthod of investigating molecularstructure. One is all too frequently confused by conflicting reportsof the assignment of the fundamental frequencies of a molecule andof its form and moments of inertia.It is hoped that this reportwill give the reader some criteria which he may apply to the workon any particular molecule.Suppose we have given the fact that a molecule absorbs in theinfra-red at wave-lengths corresponding to the frequencies vl, v2,v3 . . . . , and that it has Raman lines of frequency vll, vzl, v31 ; howdo we set about determining any of the information just quoted?We must first establish which are tlhe fundamental frequencies andwhich are the combinations and overtones of them. This is doneby the application of a judicious combination of semi-empiricalrules, together with strict selection rules derived from a quantum-mechanical treatment of the problem. The first of these empiricalrules concerns the magnitude of the frequency.Any moleculecontaining a hydrogen atom may be expected to have its highestfrequencies in the neighbourhood of 3500 cm.-l. Any molecule notcontaining a hydrogen atom is very unlikely to have any fundamentalfrequency higher than 2500 cm.-l. This enables one immediatelyto put an upper limit on which of the observed frequencies may,or may not, be fundamentals. Certain authors l1 have tended tocarry this principle still further, and to associate definite fre-quencies in the molecule with definite linkages such as the C-H,0-H, C-C, C-S, etc. This is permissible only so long as it is clearlyunderstood that it is at best a rough approximation to the truth.The C-H bond in a molecule cannot vibrate by itself and leave therest of the molecule unaffected.The molecule must vibrate as awhole, although it happens that for certain of the normal modes ofvibration the motion is principally confined to, and determined by,the force constants of one particular bond or group.The next empirical criterion is that of intensity. It usuallyhappens that the more intensely absorbed (or scattered) frequenciescorrespond to fundamental vibrations of the molecule. This, how-ever, is a rule which must be applied with even more caution than100 H. Sponer, '' Molekulspektren," Springer, 1935.11 E.g., I<. W. F. Kohlrausch, '' Der Smekal-Raman Effekt," Springer,A detailed description of the method of analysis1931 ; R. Mecke, in " The Structure of Molecules," Blackie, 193158 GENERAL AND PHYSICAII CHEMISTRY.the first.What exactly determines the relative intensities offundamentals and their corn binations is not yet clearly understood(for the selection rules give only those which are forbidden). Itfrequently happens that a fundamental is so weak as to be, to allintents and purposes, “ inactive,” although the selection rules giveit as an “ active ” frequency. This is the case in water l2 andprobably in ammonia and ph0~phine.l~ In other cases, e.g.,acetylene,14 the intensity of a combination band appears to beconsiderably greater than that of a fundamental.Another important fact is that combination frequencies are veryseldom observed in the Raman spectrum. In the particular caseof ‘‘ resonance ” with a fundamental, however, this no longer holds.Thus, in carbon dioxide l5 the overtone of the perpendicular vibra-tion (9 & 7) happens to coincide numerically almost exactly withthe symmetrical vibration (0 -> C +- 0) ; the result is that thesetwo energy levels lose their individuality, a certain proportion ofthe molecules in each vibrating in the first fashion and the remainderin the second.Thus, instead of one strong Raman line appearingcorresponding to the symmetrical vibration, and an extremelyweak one corresponding to the overtone of the perpendicularfundamental, we obtain two Raman frequencies of comparableintensity lying very close together. This phenomenon is probablypresent also in carbon tetrachloride and in the methyl halides.17Having made a provisional allotment of the possible fundamentalfrequencies, one next chooses the most likely model of the molecule,and tries to correlate the observed fundamentals with its normalmodes of vibration, the latter being deduced by classical mechanics.In this, one may apply strict selection rules, for as soon as the modelis chosen, and its vibrations determined, quantum mechanics yieldsselection rules predicting which vibrations are active in absorption,and which in Raman scattering.These rules have been derivedby several authors and are now conveniently collected in severalplaces.7918 It issufficient for our purpose to know that they depend solely on the12 E. K. Plyler and W. W. Sleator, Physical Rev., 1931, 37, 1493; also13 J. B. Howard, J .Chem. Physics, 1935, 3, 207.14 A. Levin and C. F. Meyer, J . Opt. SOC. Amer., 1928,16, 137.1 6 E. Fermi, 2. Physik, 1931, 71, 250; D. M. Dennison, Physical Rev.,16 J. Horiuti, 2. Physik, 1933, 84, 380.17 A. Adel and E. F. Barker, J . Chem. Physim, 1934, 2, 627.18 D. M. Dennison, Rev. Mod. Physics, 1931, 3, 280; L. Tisza, 2. Physik,They would take too long to reproduce here.ref. (26).1932, 41, 304.1933, 82, 48SUTWI(;LBND : SPECTROSCOPY. 50symmetry properties of the molecules, and do not involve specificassumptions about their internal structure. We may, however,consider some of their more general aspects. The appearance of afrequency in the infra-red absorption spectrum of a molecule dependson whether there is associated with that vibration of the moleculea changing electric moment.For example, the symmetricalvibration (0 I_$ C + 0) of the carbon dioxide molecule willclearly be inactive in absorption, whereas the unsymmetrical modeof vibration (0 + +- C 0 +) will be expected to cause achanging electric moment and so to be active. In the Ramanspectrum, on the other hand, it is the changing polarisability ofthe molecule which is important in determining if it will scatter lightinvolving a particular frequency; e.g., in the above two frequenciesof carbon dioxide, the selection rules for the Raman spectrum willbe the reverse of those for the infra-red. More generally, for a, mole-cule possessing a centre of symmetry, the same frequency can neverbe active both in infra-red absorption and in Raman scattering.This is of great value in assigning the fundamentals of such molecules.For molecules which have not such a, high degree of symmetry,the selection rules are more concerned with the " character " of thevibration, since, as the degree of symmetry decreases, one tends toget all frequencies active both in infra-red and in Raman scattering.The " character " of a vibration means those of its propertieswhich do not depend on tho particular force field in the molecule,but rather on its geometrical or symmetry properties, e.g., propertiessuch as whether the vibration is single or degenerate; what thedegree of degeneracy is in the latter case; whether the vibration issuch that the change of electric moment takes place only along aparticular axis of symmetry in the molecule.The last is of greatimportance, since the rotational fine structure of a vibration bandcan differ profoundly according to the direction of vibration of theassociated electric moment within the molecule.Although these selection rules will usually enable a definite modelt o be chosen for the molecule (vix., one having the required degreeof symmetry) the final assignment of particular fundamentalfrequencies to particular modes of vibration can only be madecompletely certain by an examination of the rotational fine structureof some of the observed bands. So far, this is only practicable inabsorption, since Raman scattering in the gas is too weak (withpresent methods) to give more than the central (Q) maximum of theband.Even in absorption, we are seriously limited by the lowresolving power of the spectrometer. Up to the present, the smallestline separation which can be resolved is of the order of 0-5 cm.-1.To realise the full import of this limitation, it is necessary to con60 GENERAL AND PHYSICAL CHEMISTRY.sider the rotational fine structure of the different classes of moleculein a little detail.There are two types of band, and two only, ac-cording as the vibration of the electric moment takes place along, orperpendicular to, the symmetry axis of the molecule. The line spacingin each is the same and is given by h / 4 x I ~ in frequency units. Thelinear molecules for which it has been possible to resolve this spacingare carbon dioxide, nitrous oxide, hydrogen cyanide, and acetylene.loaIt seems unlikely that many more complicated molecules can beinvestigated in this way since the spacing for nitrous oxide l9 isalready only 0.8 cm.-l.I n cases of heavier molecules, however, itis possible to make an estimate of the moment of inertia by measuringthe spacing between the intensity maximum of the P and the Rbranch of the band, which is given by the classical formula of Bjer-rum, ( ~ W ) / X . ~ O This has been done for carbon disulphide.21There are again two types of band.The first corresponds to vibration of the electric moment along thesymmetry axis of the molecule, and resembles very closely the per-pendicular type band of a linear molecule. The spacing of the linesis given by h/4x21*, and so gives no information about the moment,of inertia -lo.The other type of band associated with vibrationof the electric moment perpendicular to the symmetry axis of themolecule is very complicated indeed, consisting of sets of overlappingbands. The spacing between the lines depends on both of themoments of inertia, and so, knowing I A from the parallel bands,one might expect the deduction of I c from the perpendicular bandsto be an easy matter. That this is far from being the case is due fotwo causes: first, the excessive number of lines makes them in-capable of resolution except in a few favourable cases (vix., wherel A > l a ) , and secondly, the spacing (when it can be determined)is not found to be the same in the different bands.The latterphenomenon has long worried spectroscopists, and it is only in thepast year that this difficulty has been completely resolved. Thequalitative explanation was first given by E. Teller and L. Tisza,22who showed that it was due to the imperfect coupling which mayexist between rotation of the molecule and degenerate vibrations ofthis type in a symmetrical molecule. To put it very roughly, thevibration itself may have a characteristic angular momentumwhich can be coupled to that due to rotation of the molecule as aLinear molecules.Symmetrical top molecules.19 E. K. Plyler and E. F. Barker, Physical Rev., 1931,38, 1827.20 Here k is Boltzmann’s constant, and T the absolute temperature.21 C. R. Bailey and A.B. D. Cassie, Proc. Roy. SOC., 1931, [ A ] , 132, 236;22 2. Phyeik, 1932, ’73, 791.{bid., 1933, [ A ] , 140, 605SUTRERLAND : SPECTROSCOPY. 61whole. It is readily understandable that such a phenomenonwould lead to anomalous spacingx, as the coupling factor neednot be the same for each mode of vibration. More recently, E.Teller 23 gave a quantitative theory, in which he showed that althoughthe spacings in the separate bands could not be predicted withouta knowledge of the force constants controlling the vibrations, yetthe sum of the spacings in all the bands was a function only of themasses and of the inter-nuclear distances in the molecule.Unfortunately, Teller’s work contained some errors, but M. Johnsonand D. M. Dennison 24 have finally given the simplest expressionfor the sum of the spacings in terms of the moments of inertiaof the molecule.Thus, they were able for the first time to giveaccurately the moments of inertia of methane and the methylhalides. In cases where the moments of inertia are so large that itis impossible to resolve the individual rotation lines, a fair estimateof them may be obtained by a carefiil measurement of the separationand intensity of the two extreme maxima in the “ parallel ” bands.25For these molecules the positionis not nearly so simple. Here, as we have said, there is no explicitexpression for the rotational energy, but to each value of therotational quantum number J there correspond 2J + 1 levels, andthe selection rules governing transitions between all these levelscannot be given in a short space.The resulting band structure isextremely complex and apparently hopelessly irregular. However,given patience and a rough idea of the values of the moments ofinertia, there is no reason why it should not be analysed and thishas been accomplished successfnlly for waterySB hydrogen sulphide,27formaldehyde,28 and ethylene.29 It will be noticed that each ofthese molecules contains at least one hydrogen atom, and it is veryunlikely that any asymmetrical top molecule not containing ahydrogen atom will have its vibration-rotation analysed for along time to come. The resolving power of present spectrometerswill have to be improved by an order of magnitude before sufficientstructure will be obtained to justify an attempt at analysis.Yetthe position is not so hopeless as this sounds, for, as in the othertypes of molecule, the contour of the unresolved band gives someguide as to its f0rrn,~0 Thus, it appears that the contour of a band2.1 LOC. cit., ref. (7).2 5 S . L. Gerhard and D. M. Dennison, {bid., 1933, 45, 197.26 R. Mecke, 8. Physik, 1933, 81, 313; R. Mecke and W. Baumann, ibid.,p. 445; K. Freundenberg and R. Mecke, ibid., p. 465.27 P. C. Cross, Physical Rev., 1935, 47, 7.28 H. H. Nielsen, ibid., 1934, 46, 117.29 R. M. Badger, ibid., 1934, 45, 648.313 D. M. Dennison, Rev. Mod. Physics, 1931, 8, 280.AsynzmetricaE top molecules.24 Physical Rev., 1935,4’9, 93 ; 48, 86862 GENERA& AND PHYSIUAL CHEMISTRY.which corresponds to a vibration of the electric moment along thegreatest axis of inertia will exhibit a strong but rather broad central(Q) maximum together with symmetrically disposed minor (P andR) maxima.For a vibration along the middle axis of inertia, onewould expect the central (Q) branch to be absent, while for avibration along the least axis of inertia, a very sharp and well-defined Q branch is to be expected in addition to the '< P " and " R ''maxima. These qualitative rules are well exemplified in the spectraof water,31 hydrogen ~ulphide,~~ ethylene,33 and sulphur dioxide,34but attempts to apply them quite generally, e.g., to ozone35 andnitrogen peroxide,36 have led to difficulties. This is not surprisingseeing that they are only an extrapolation from calculations on thepossible transitions for J < 5.It may be that future theoreticalwork will lead to their being modified for heavier molecules.To sum up, it is now possible to determine the general form andfundamental frequencies of the simpler polyatomic molecules,and to assign each fundamental to a particular mode of vibrationof the model. Only in the hydrogen-containing molecules (and a fewlinear ones such as carbon dioxide or carbonyl sulphide) does itseem possible to obtain accurate values of the moments of inertiawithout a great increase in resolving power of spectrometers in theinfra-red. The only obvious line of advance would be t o observeovertones (instead of fundamentals), which fall in the photographicregion.Unfortunately, it is just those molecules whose overtoneshave a measurable intensity in the photographic region, v k , thehydrogen-containing ones, which are already amalysed.Although an immense amount of workhas been done on the electronic spectra of polyatomic molecules,there is remarkably little which can be said to be of significancefrom the true spectroscopic point of view ; in other words, very littleof it can be interpreted to yield the energy states of the absorbingor emitting molecule. This is not surprising, since the theory ofsuch spectra has only been developed in the last three years. Thefirst step was made by R. S. Mulliken 37 who showed how the elec-tronic levels may be classified by means of their symmetry properties,C.EEectronic spectra.31 E. K. Plyler and W. W. Sleator, Physical Rev., 1931, 37, 1493; and32 A. D. Sprague and H. H. Nielsen, ibid., 1933, 43, 375.33 A. Levin and C. F. Meyer, J . Opt. SOC. Amer., 1928, 16, 137.34 C. R. Bailey and A. B. D. Cassie, Proc. Roy. SOC., 1932, [A], 137, 622;35 G. Hettner, R. Pohlmann, and H. J. Schumacher, 2. Phpik, 1934,91,372.3C G. B. B. M. Sutherland and W. G. Penney, Nature, 1935,135,958.s7 Physical Rev., 1932, 40, 55; 41, 49; 1933, 43, 279; J . Chern. Physics,ref. (26).C. R. Bailey, A. B. D. Cassie, and W. R. Angus, ibid., 1930, 130, 133.1933, 1, 492; 1935,3, 375, 506, 514, 517, 564, 635, 720SUTHERLAND : SPEUTROSCOPY. 63and by extrapolating from close analogies with well-known diatomicspectra. G.Herzberg and E. Tellor, and others,38 have now con-sidered the selection rules which govern the associated vibrationaltransitions, while the rules for the rotational transitions followreadily from those applicable to vibration-rotation spectra. Togo into all these matters in detail is impossible in the space allotted,and we reserve their discussion for a future Report. We can nowonly mention a few of the more siiccessful attempts to apply andtest the theory.The first electronic spectrum to be analysed was that of formalde-hyde. The rotational structure of several bands was analysed byG. H. Dieke and G. B. Kistiako~sky,~~ enabling them to give themoments of inertia of the molecule in the ground and excited stateswith considerable accuracy.The interpretation of the electronictransition and the deduction of the nature of the electronic states isdue to R. S. M~lliken.~~ Another important success was achievedin the methyl halides,41 although in this case the rotational structurecannot yet be satisfactorily resolved. E. Eastwood and C. P. Snow 42have examined the spectra of a series of aldehydes; it appears fromtheir results that these are not due (as was formerly supposed) tothe excitation of an electron in the carbonyl bond, but to theexcitation of one of the non-localised electrons of the carbon atom.They also obtained some remarkably simple bands from acraldehyde,which could best be represented as isolated R branches fitting theusual parabolic formula. Unfortunately, these do not give consistentvalues for the corresponding " moment of inertia " and theirexplanation is at present obscure.Other molecules with whichsome progress has been made are S02,43 C2H2,44 C2H4,45 NH3,46CO,:' CS2,$8 HCN,49 and N2H4.49There is one very important advance on the experimental sideto be reported. This is the development of a new type of Lymancontinuum for the extreme ultra-violet by G. Collins and W. C.3* Z. physikal. Chem., 1933, [B], 21, 410. Also A. E. F. Duncan, J. Chem.Physics, 1935, 3, 384.Physical Rev., 1934, 45, 4. 40 Ibid., 1935, 47, 413.41 Refs. (38) and (40). 42 Proc. Roy. SOC., 1935, [ A ] , 149, 434.43 J. H. Clements, Physical Rev., 1935, 47, 224; R. K. Asundi and R.44 W. C. Price, Physical Rev., 1934, 45, 843; ibid., 1935, 47, 444; H.4 6 H.J. Hilgendorff, 2. Physik, 1935, 95, 781; see also refs. (38) and (44).4 6 A. B. F. Duncan, Physical Rev., 1935, 47, 822.47 Idem, J . Chem. Physics, 1935, 3, 384.4 8 W. W. Watson and A. E. Parker, Physical Rev., 1931, 37, 1013; and49 H. J. Hilgendorff, 2. Physik, 1935, 95, 781.Samuel, Proc. Indian Acad. Sci., 1935, 2A, 30.Gopfert, 8. wi8s. Phot., 1935, 34, 156.ref. (47)64 GENERAL AND PHYSICAL CHEMISTRY.P r i ~ e . ~ o As a result, W. C. Price 51 has been able to photographabsorption spectra of many polyatomic molecules as far down as300 A. He has found the very interesting result that most of thesimple molecules exhibit bands in this region which can be arrangedin Rydberg series. He has thus been able to find the ionisationpotentials of several of the simpler molecules such as acetylene,ethylene, water, hydrogen sulphide, and the methyl and ethylhalides.Spectra of Deuterium Compounds.-The early work on the spectraof deuterium and its simpler compounds has already been reviewed ;52this report is accordingly confined almost entirely to work which hasappeared during the past year.For the best documented anddetailed report of the early work the review of H. C. Urey and G . K.Teal 53 is, of course, the standard reference. Work on the spectraof deuterium compounds has, roughly speaking, one of four objectsin view : (1) the investigation of the accurate theory of the isotopeeffect in diatomic spectra and the elucidation of certain perturbationproblems in such spectra, (2) the determination and assignmentof doubtful fundamental frequencies in polyatomic molecules,(3) the determination of internuclear distances in polyatomicniolecules containing hydrogen, and (4) the determination ofpotential functions for polyatomic molecules.As regards (l), certain difficulties arose when it was found byW.Holst and E. Hulthkn 54 that the “ B values ” (these define thespacing of the rotational structure of the band) did not have theexpected ratio for A1H and A1D. These authors explained this asdue to the neglect of the moment of inertia of the electron cloud.R. de L. K r ~ n i g , ~ ~ however, gave an entirely different explanationbased on the fact that a certain interaction term giving the reactionof the nuclei to the precession of the electronic angular momentumhad been neglected.Unfortunately, Kronig’s theory cannot givethe whole truth for, according to it, there should be no anomalyfor DC1, LiD, or NaD. Now, although the first does not have thean0maly,~6 the other two do.57 The whole theory has been carefullyreviewed by G. H. Dieke,58 who has shown that Kronig’s theory50 Rev. Sci. In&+., 1934, 5, 423.51 Ref. (44); J . Chem. Physics, 1935, 3, 256.52 Ann. Reports, 1933 and 1934.54 2. Physik, 1934, 90, 712.5 8 J. D. Hardy, E. F. Barker, and D. MI. Dennison, Physical Rev., 1932,57 F. H. Crawford and T. Jorgensen, ibid., 1934, 46, 746; E. Olsson, 2.Physical Rev., 1935, 47, 661; 48, 606; G. H. Dieke and R. W. Blue,53 Rev. Mod.Physics, 1935, 7, 34.65 Phy8ica, 1934, 1, 621.42, 279.Physik, 1935, 93, 206, 816.ibid., 1935, 47, 261SUTHERLAND : SPECTROSCOPY. 65(supplemented by corrections for anharmonic factors) will accountcompletely for the isotope effect in the spectra of HD and D,, butthat it is not capable of explaining the defects of heavier molecules.Since then, more experimental work has been done,59 and the im-portance of anharmonic corrections demonstrated.GO The completetheoretical explanation is still, however, some way from achievement.The determination and assignment of doubtful fundamentalfrequencies by means of the isotope effect is likely to become oneof the more important applications of the discovery of deuteriumto spectroscopy. A very striking example is afforded by benzene,for which there has long been the anomaly that certain of the Ramanfrequencies appear to coincide with fundamental absorption fre-quencies in the infra-red. The apparent conclusion that thebenzene molecule does not have a centre of symmetry has not foundfavour in view of the theory of " resonance " between possibleKekul6 structures.If, however, this coincidence of infra-red andRaman frequencies were purely fortuitous, then it would not beexpected to occur for the isotopic form, hexadeuterobenzene.Recent work here 61 and in America,62 although not yet final, alltends to show that the agreement was indeed fortuitous, andthat benzene is symmetrical. Other applications towards theassignment and identification of fundamentals have been made inthe cases of water,63 ammonia, p h ~ s p h i n e , ~ ~ and chloroform.65In the third type of application we would mention the accuratedetermination of all the internuelear distances in the moleculesacetylene,6G hydrogen ~yanide,~ 7 methane,G8 and ammonia.68aThe final and possibly most important application is in connexionwith the determination of the most suitable potential function to69 F. H. Crawford and T. Jorgensen, Physical new., 1935,47,358,932 ; W. W.Watson, ibid., p. 27; A. Guntsch, 2. Physik, 1935, 93, 534; B. Grundstrom,ibid., 1935, 95, 574; Y. Fujioka and T. Wada, Sci. Papers I n s t . Phys. Chem.Res. Tok?yo, 1935, 27, 210.60 P. G. Koontz, Physical Rev., 1935, 48, 138.W. R. Angus, C. R. Bailey, C.K. Ingold, A. H. Leckie, C. G. Raisin,J. W. Thompson, and C. L. Wilson, Nature, 1935, 135, 1033 ; 136, 680.62 R. B. Barnesand R. R. Brattain, J . Chem. Physics, 1935, 3,446; R. W.Wood, ibid., 3, 444.G3 C. H. Cartwright, Nature, 1935, 136, 181; R. Ananthakrishnan, Mem.Ind. Inst. Sci., 1935, 2, No. 21, 291.64 J. B. Howard, J . Chem. Physics, 1935, 3, 207.65 R. TYV. Wood and D. H. Rank, Physical Rev., 1935, 48, 63.6 6 G. Herzberg, F. Patat, and J. W. T. Spinks, 2. Physik, 1934,92, 87.67 P. F. Bartunek and E. F. Barker, Physical Rev., 1935, 48, 516.6s N. Ginsburg and E. F. Barker, ibid., 1935, 47, 641; J . Chenz. Physics,685 R. B. Barnes, Physical Rev., 2935, 47, 658; E. F. Barker and M.1935, 3, 668.Migeotte, ibid., p. 702.REP.-vOL. XXXII.66 GENERAL AND PHYSICAL CHEMISTRY.represent the force field controlling the vibration of the atoms in apolyatomic molecule. Many attempts have been made to do this,69but none has been more than partially successful, since more con-stants are required to define the force field than there are frequenciesby which to determine them. The introduction of a deuterium inplace of a hydrogen atom leaves the force field unchanged (to thedegree of approximation involved here) while yielding a new set offrequencies. The problem then is no longer indeterminate. Con-versely, any force field which was chosen in an empirical way toagree with the earlier data, may now be tested by qeeing how wellit predicts the frequencies of the deuterium compound. Thegeneral theory of the isotope effect has been given by severalauthors ; 7* applications have already been made to acetylene,71waterY72 hydrogen cyanide,67 ammonia,73 phosphine,6* methane,aiid the methyl halides.74 G.B. B. M. S.4. THE DETERMINATION OF THERMODYNAMIC CONSTANTS FROMSPECTROSCOPIC DATA BY STATISTICAL METHODS.The energy of a molecule may be divided into two independentparts : one is concerned with translation only, and the other involvesall forms of internal energy. The portion, due to translation, of athermodynamic function, e.g., entropy, total energy, or heat capacity,of any molecule in the ideal gaseous state is virtually the whole ofthe value for a monatomic gas. This problem has been treated bya number of authors,l and the equation for the entropy of a mon-atomic gas-the well-known Sackur-Tetrode equation-may bewrittens = R [ ~ ~ ( Z ~ I ~ ~ T ) ~ / ~ V V / I L ~ N + ;-I .. . (1)See Ann. Reports, 1934, 31, 21 ; J. E. Rosenthal, Physical Rev., 1934, 45,426 ; 46,730 ; ibid., 1935,47,235 ; G. B. B. M. Sutherland and D. M. Dennison,Proc. Roy. SOC., 1935, [ A ] , 148, 250; A. B. D. Cassie, ibid., p. 87.70 E. Teller, loc. cit., ref. ( 7 ) ; 0. Redlich, 2. physikal. Chem., 1935, [B],28, 371 ; J. E. Rosenthal, loc. cit.71 G. B. B. M. Sutherland, Nature, 1934, 134, 7 7 5 ; W. F. Colby, PhysicalRev., 1935, 47, 388; Y. Morino, Sci. Papers Inst. Phys. Chem. Res. Tokyo,1935, 25, 232 ; 27, 39 ; see also ref. (66).72 L. G. Bonner, Physical Rev., 1934, 46, 458; J. E. Rosenthal, Eoc.cit.,ref. (69); R. Ananthakrishnan, loc. cit., ref. (63).73 M. F. Manning, J . Chem. Phyeics, 1935, 3, 136; see also ref. (64).74 M. Johnson and D. M. Dennison, Physical Rev., 1935, 47, 93; 48, 868.0. Sackur, Ann. Physilc, 1911, 36, 958; 1913, 40, 67; A., 1912, ii, 145;1913, ii, 128; H. Tetrode, ibid., 1912, 38, 434; 1913, 39, 255; 0. Stern,Physikal. Z., 1913, 14, 629; Z. Elektrochem., 1919, 25, 66; A., 1919, ii, 219;P. Ehrenfest and V. Trkal, Proc. K . Akad. Wetensch. Amsterdam, 1920, 23,162; Ann. Physik, 1921, 65, 609; A , , 1920, ii, 738; L. S. Kassel, Chem.Reviews, 1936, in the pressGLASSTONE : DETERMINATION OF THERMODYNAMIC CONSTANTS. 67where R is the gas-constant, k the Boltzmann constant, m the weightof a single molecule, T the absolute temperature, V the volume of1 g.-mol.in c.c., h the Planck constant, and N the Avogadro number.This expression represents the translational entropy of any idealgas, and for practical purposes at 1 atm. pressure, it may be put.in the formR is now expressed in calories, and M is the molecular weight ofthe gas. Similarly the translational energy of any gas has thevalue $BT per g.-mol., and the corresponding heat capacity isgB ; these results follow, of course, from the kinetic theory.For polyatomic molecules the portion of the various thermo-dynamic functions due to internal energy must now be considered .2If the Maxwell-Boltzmann distribution law applies to a system, thenthe number of molecules in any state represented by i, is piAe4"lkT,pi being the " a priori probability " or " statistical weight " of theith state, A the number of molecules in the state of lowest internalenergy, and ci the internal energy per molecule in the given state,with reference to the lowest energy state.* The statistical weightrepresents the degeneracy, or multiplicity, of the energy level underconsideration: in terms of wave mechanics it is the number ofproper values (eigenvalues) which satisfy the wave equation for themolecule in the particular quantum state.Actually these valuesdo not correspond to states of identical energy, but the differencesare so small that they may be grouped together in one state witha probability p equal to the number of eigenvalues. In 1 g.-mol.of a gas the total number of molecules, i.e., the Avogadro number,is equal to the sum of the molecules in the various states characterisedby i = 0, 1, 2, 3, .. . ; hence N = AXpe-e/kT. Similarly,the internal energy of all the molecules in a given state is &pAe-&lkT,and the total internal energy Eojnt. of 1 g.-mol. of gas, with referenceto the zero state, is A&pe-&IkT. Combining this relationship with theequation for N , it follows thatSotr. = &RlnM + &RlnT - 2.300 . . . (2)2 The treatment given here is essentially that of W. F. Giauque, J. Amer.Ghern. SOC., 1930, 52, 4808.* The convention adopted in the treatment given here is to take as thezero the energy of the molecule at rest and with vibrational and rotationalquantum numbers equal to zero ; i.e., the value of E is effectively the diflerencebetween the total engrgy and the zero-point energy (the energy a t 0" Abs.).It will be seen later (p.70) that some authors take the molecule in its dis-sociated state, i.e., in the form of atoms, t o represent the zero from whicht o take the E values. Whichever convention is adopted, the final resultxnuat be the same (compare R. H. Fowler, " Statistical Mechanics," 1929,p .26, footnote)68 GENERAL AND PHYSICAL CHEMISTRY.where Q is equal to Cpe-&IkT, and is known as the “ summation ofstate ” or “ state sum ” (“ Zustandsumme,” Planck) or “ partitionfunction ” (Fowler). Strictly speaking, the equation given appliesonly if the Maxwell-Boltzmann distribution holds, and this is cer-tainly not the case for real gases, especially a t low temperatures;the assumption of an ideal gas, however, permits the use of the.classical law, and in any case a t appreciable temperatures theBose-Einstein and Fermi-Dirac statistics lead to the same result .3The differentiation of Eoht.with respect to temperature givesan expression for the heat capacity of a perfect gas due to internaldegrees of freedom,4 thusAlternatively, this equation can be writtenwhere XA = Q ; U3 = ET2(dQ/dT); and XC = 2E2T3(dQ/dT) +k2T4( d2Q/dT2).By making use of the definition of internal entropy in the formdXint. = Cint. d In T , it follows that the entropy due to internaldegrees of freedom is given byXoint. = R[ln Q + T d In QldT] . . . . . .(7)= R[lnA + (l/kT)(CB/CA)] . . . . (8)= R[ln Cpe-&IkT + C ~ ~ e - & ‘ ~ ~ / k T C ~ e - & l ~ ~ ] . (9)From any of these equations it is possible to calculate the internalentropy of an ideal gas, and the addition of the translational entropy,equation (2), gives the value of Xo7 the total entropy a t atmosphericpressure. If necessary, a correction can be applied for deviationsW. F. Giauque, loc. cit.; G. N. Lewis and J. E. Mayer, Proc. Nat. Acad.Sci., 1929, 15, 208; A., 1929, 648; W. H. Rodebush, Chern. Reviews, 1931,9, 319; H. L. Johnston and M. K. Walker, J . Amer. Chem. SOC., 1933, 55,182 (footnote).Cf. F. Rciche, Ann. Physsik, 1919, 58, 657; H. C. Urey, J . Amer. Chem.Soc., 1923, 45, 1445; A . , 1923, ii, 533; R. C. Tolman and R.M . Badger,ibid., 1923, 45, 2277; A., 1923, ii, 830; H. C. Hicks and A. C. G. Mitchell,ibid., 1926, 48, 1520; A., 1926, 784.H. L. Johnston and A. T. Chapman, ibid., 1933, 55, 153; A., 1933, 229.H . C. Urey, Zoc. cit.; R. C. Tolman and R,. B!L Badger, Zoc. cit.; H. C.Hicks and A. C. G. Mitchell, loc. citGLASSTONE : DETERMINATION OF THERMODYNAMIC CONSTANTS. 69from ideal behaviour, but this is quite small, especially a t temper-atures high enough to be of chemical interest.'The free energy Po in the standard state, i.e., ideal gas a t I atm.pressure, may be expressedPo= E"+IZT-TS" . . . - (10)where E" and X" refer to the total energy and entropy, respectively,including the translational terms. The total energy E'" must alsoinclude the energy of the gas a t assumed zero state, i.e., the zero-point energy (Eoo), in addition to the energy of translation (gRT),and the internal energy (Eoint.) obtained from equation (3).Itfollows, therefore, thatF" - Eoo = - 4RT Jn M - SRT In T - RT In Q + 7.267T (11)By combining the F" - E," values for resultants and reactants,it is possible, provided Q be known, to determine A(F" - Boo) fora chemical reaction, and this is related to the thermodynamicequilibrium constant. By definition, in this case, AF" = - RT In Ifpwith pressures in atms., and hence- A(F" - Eoo) = RT In K p + AE," . . (12)The calculation of Kp for a reaction involves a knowledge of- A(F" - E,") for the substances concerned in the process,evaluated from equation (ll), and of AE," for the reaction as awhole.The latter quantity may be determined by combiningappropriate spectroscopic data for heats of dissociation, since theseare values for the lowest energy level, or by means of the zero-point energies of the molecules, including all modes of vibration,also obtained from band spectra. The Eoo for an atom must bestated on the basis of the assumed energy zero as a moZecuZe.Alternatively, if AH", the heat of reaction a t constant pressure, isknown, then since H" = E" + RT, it can be readily shown, by meansof equation (lo), thatAE," = AH" - A[-ZRT + RT2(dln&/dT)] . (13)The factor + 7-267 in equation (11) arises, as may be seen froma consideration of this and equations (1) and (2), from the termR In (2xk/h2N)3'2k/a, where a is the normal atmosphere in dynes persq. em., i.e., 1.0132 x 106, and if this is introduced into equation(1 1) it becomesF" - E," = - R T I n [$(2,m~T/h2)3/2k/'ja] .(14)7 See, e.g., W. IF. Giauque, J . Amer. Chem. SOC., 1930, 52, 4822; A. R.Gordon, J. Chem. Physics, 1933,1, 30870 GENERAL AND PHYSICAL CHEMISTRY.A further obvious modification leads toPo == - AT In ([e-"oo/"~Q(2xmrcT/h)3'2](kT/a)) . (15)- RTlnG(kT/a)* . . . . . . ' (16) -where G is equal to the term in the square brackets.it is evident, since AF" = - RT In K p thatFor anyreversible chemical reaction aA + bB . . . J --- mM + nN . . . ,where v = (m + n + . . .) - (a + b + . . .). Some authors omitthe factor (kT/a)', thus giving Ke with concentrations expressed inmolecules per c.c., whereas others omit a only, which gives Kpwith pressures in dynes per sq.em. instead of in atmospheres. If vis zero the IPS are, of course, all identical. The quantity G, whichmay be regarded as the complete partition function of any molecularspecies under given conditions, is made up of three separate terms.The portion (2mET/h2)3/2 is effectively the partition function fortranslatory motion with three degrees of freedom,s and Q is thefunction for vibration and rotation, including nuclear-spin effectsand internal rotation within the molecule ; there still remains the" zero-point '' factor e--Eo"/RT. If the zero of energy, for the purposeof calculating the vibrational and rotational partition function, istaken as the energy of the free atoms,g formed by the molecule whencompletely dissociated, at their lowest levels, then a quantitye-Eo''RT actually becomes included in the vibrational function, Eo'being the heat of dissociation of the molecule a t 0" Abs.The energyterm in the " zero-point " factor is altered by this same amount,thus leading to a value identical with G for the partition functi0n.t8 R. H. Fowler, " Statistical Mechanics," 1929, p. 114.* The corresponding equation for hydrogen given by E. Teller and B.Topley (J., 1935,877) should not contain the EOo term (private communicationfrom Mr. B. Topley). The position of the large bracket also appears to havebeen misprinted. t The subjects of equilibrium constants and partition functions have beendealt with at length because of the apparent confusion facing a newcomerto the literature.Writers who employ Q generally use it in the sense definedabove, and Q' is often used for e-Jo'IRT X Q , but not consistently. H. C.Urey and D. Rittenberg ( J . Chem. Phylsics, 1933, 1, 137) define Q withoutthe zero-point factor, but H. C. Urey and G. K. Teal (Rev. Mod. Physics, 1935,'7, 52) include it in some cases, although not in others. H. C. Urey and L. J.Greiff ( J . Amer. Chem. SOC., 1935, 57, 321) define the " summation of state,"given the symbol Q , to include the e-~oo/Rp term, and use f, which is equal toGkT, as the " distribution function." The " distribution function " f ofR. H. Crist and G. A. Dalin ( J . Chem. Phy8ic8, 1934, 2, 735) is virtuallyIdem, ibid., p.103BLASSTONE : DETERMINATION OF THERMODYNAMIC CONSTANTS. 71In order to apply the equations given above to evaluate thermo-dynamic constants, the essential point remaining is the determinationof Q : to calculate this quantity the pe-E/kT terms must be summedover all possible energy states of the molecule. The energy of eachstate can be obtained from spectroscopic data with the aid of thefundamental equation of the quantum theory, E = hcv, but there issome difficulty in the assignment of the correct statistical weights( p ) ; it was the use of incorrect values which invalidated the earlierapplications lo of some of the equations deduced here. The prin-ciples involved in the determination of the partition function, whichare based on wave mechanics, may be conveniently consideredseparately for (a) atoms and monatomic molecules, ( b ) diatomic,and (c) more complex molecules.Atoms and Monatomic Molecu.les.--The value of Q is given by theproduct of the function for nuclear-spin orientation and that forevery possible electronic configuration.The nuclear-spin functionis equal to the corresponding statistical weight, since E is zero, andis given by 2is + 1, where is is the number of units of nuclear-spin momentum; this quantity represents the total number ofpossible orientations, having nearly the same energy, of the nucleusin a perturbing field. The p factor for each electronic configurationis 2js + 1, where js(= I 5 s), which cannot be negative, resultsfrom the combination of the azimuthal quantum number (1) and theresultant spin (s) of the electrons; to obtain the partition functionthis weight must be multiplied by e-&lkT for the appropriate state,and summed over all possible configurations indicated by spectro-scopic data.This apparently impossible task is simplified by thefact that the quantity e-&lkT has a significant value only a t temper-atures exceeding hcv/4lc, where v in cm.-1 is the frequency separationof the given energy level above the ground level.ll Hence, it isonly at high temperatures that any level other than the groundstate ( E = 0) need be considered. With atomic hydrogen, foridentical with our C, and so also, apparently, is the G of E. Teller and B.Topley (J., 1935, 876), although the latter authors employ a different energy-zero convention.The partition function P employed by B. Topley and H.Eyring ( J . Chem. Phyt?/sics, 1934, 2, 217) is evidently e--Bo'/RE times the productof Q and the translational factor; since ABo' is equal to AE,', this function Ir'may replace C. in the calculation of equilibrium constants. The partitionfunction F used in chemical kinetics (see p. 94) is G with the zero-pointfactor omitted.10 H. C. Urey ; R. C. Tolman and R. M. Badger; H. C. Hicks and A. C. G.Mitchell, Eocc. cit., ref. (4); see also D. 5. Villars, Proc. iVut. Acad. Sci., 1929,15,705; 1930,16,396; A., 1929, 1236; 1930, 1121.11 J. E. Mayer, S . Brunauer, and M. C:. Mayer, J . Amer. Chem. SOC., 1933,55, 37; A., 1933, 218; H.Zeke, 2. Elektrochem., 1933, 39, 76272 GENERAL AND PHYSICAL CHEMISTRY.example,12 is = +, and so the corresponding partition function is2 ; the electronic ground level (n = 1) is a singlet state with j, = 4,and since E = 0, the electronic function is also 2. Since no higherlevel need be considered, the complete partition function is 4, therebeing no vibrational or rotational energy for an atom. The nuclearspin of the chlorine atom is $, and so the nuclear-spin function is 6 ;spectroscopic evidence indicates the ground state to be an inverted2P doublet, with js values of $- for the lower and 8 for the upperlevel, the frequency separation being 851 cm.-l. The statisticalweights for the two levels, i.e., 2js + 1, are 4 and 2, respectively,and hence the electronic partition function is 4 + 2e--881hc/kP;the complete function for the atom is then obtained by multiplyingby 6 for the nuclear spin.No other energy levels need be consideredfor all reasonable temperat~res.1~ The ground level of normalatomic oxygen is an inverted 3Y term, the js values being 2, 1, and0, respectively, and the frequency separations 157.4 cm.-l and226.1 cm.-l; the electronic partition function is thus 5 + 3e-157.4hc/k' + 1e-226.1hc/kP. At high temperatures it is also necessary to includethe contributions for the two metastable levels consisting of lDZand lX0 terms, respectively. Since the oxygen nucleus has no spin,is = 0, the complete partition function is the same as the electroniccontribution.l* The literature may be consulted for other cases,which present no novel features.15Diatomic Molecules.-The Q value for a molecule containing twoor more atoms involves summation over every possible electronic,vibrational, and rotational state ; in general, electronic levels abovethe ground state necd no$ be considered, for reasons already given.The multiplicity, if any, of the ground level must, however, be in-cluded. Most diatomic molecules have 12 ground terms, and sothere are no multiplet levels; nitric oxide, oxygen, hydroxyl, andthe cyanide radical, amongst others, are, however, exceptional.16The energy separation of successive vibrational levels is relativelysmall, and so it is necessary to sum the pe-&lkF terms over severallevels; unless approximation methods are used (see below), only afew of the lowest states are actually included, especially at low12 W.3'. Giauque, J . Amer. Chem. SOC., 1930, 52, 4816; A., 1931, 294.l3 W. F. Giauque and R. Overstreet, ibid., 1932, 54, 1731; A., 1932,695.14 H. L. Johnston and M. K. Walker, ibid., 1933, 55, 187; A., 1933, 229;G. van Elbe and B. Lewis, ibid., p. 507 ; A., 1933, 350.15 W. F. Giauque and J. 0. Clayton, ibid., p. 4875; L4., 1934, 135; H. L.Johnston and E. A. Long, J . Chem. Physics, 1934, 2, 389; A., 1934, 951;C. W. Montgomery and L. S. Kassel, ibid., 1934, 2, 417; A., 1934, 966; H.Zeise, 2. Elektrochem., 1934, 40, 665.l6 W. Jevons, '' Band Spectra of Diatomic Molecules," 1932, Appendix IIGLASSTONE : DETERMINATION OF THERMODYNAMIC CONSTANTS.73temperatures. For example, with hydrogen it is only the lowestvibrational level (v = 0) which contributes appreciably to thepartition function at temperatures below 900" Abs. ; even a t 2000"Abs. only the first four levels (v = 0, 1, 2, 3) nced be considered.17With oxygen and nitric oxide, however, five levels must be includedbelow 900" Abs., the number increasing up to 12 a t 2000" Abs., ineach multiplet.l*Each rotational state has, in addition to the rotational degeneracyresulting from nuclear spin, a statistical weight of 2J + 1, whereJ is the rotational quantum number. If the molecule has two,similar nuclei with spin is, the total statistical weight of each rota-tional level in a Cf state is obtained by multiplying the 2J + 1value by the nuclear-spin factor (i, i- a)(%, + l), for even values ofJ (including zero), and by i, (Zi, + 1) for odd values of J , if the nucleifollow the Bose-Einstein statistics, but the factors are reversedif the Fermi-Dirac statistics are followed.Ordinary hydrogenobeys the latter statistics, and since i, = 8, even levels have pvalues equal to 2J + 1, and for odd levels they are 3(2J + I),resulting in the well-known alternation of the spectral lines, and theproportions of o- and p-hydrogen in the normal gas. Deuteriummolecules, on the other hand, have is = 1, and follow the Bose-Einstein statistics; hence the statistical weights for even andodd levels are 2(2J + 1) and 2J + 1, respectively.The nuclear spin of the oxygen atom is zero, and consequentlyfor the symmetrical 0l6Ol6 molecule, the main constituent of oxygengas, alternate rotational levels have statistical weights of 2J + 1and zero; only alternate rotational levels, for odd values of J , areconsequently present, the normal state being 3C,- and the Bose-Einstein statistics being followed.20 The components of the tripletterm have been called the Fly F2, and F, coupling states (Hund'scase-b).The coupling energy of the %12 state is about 2 cm.-l(ca. 6 cals.) : this amount is so small that all three states may beregarded as having the energy of the lowest level, i.e., 6 = 0. Thevalue of J in calculating the rotational statistical weight is determinedby the rotational quantum numbers, which are K + 1, K , and K - 1,respectively, for the levels F,, F,, t-md F3, only odd values of Kbeing permitted ; the corresponding y values are, therefore, 2K + 3,2K -t 1, and 2K - 1, where K has the values 1, 3, 6, etc.The1 7 C. 0. Davis and H. L. Johnston, J. Amer. Chem. SOC., 1934, 56, 1045;18 H. L. Johnston et ul., ibid., 1933, 55, 153, 172; A,, 1933, 229.19 G. N. Lewis and M. F. Ashley, Physical Rev., 1933, 43, 837; H. C. Urey20 W. Jevons, op. cit., p. 290, etc.A., 1934, 722.and D. Rittenberg, J. Chem. Physics, 1933,1, 137; A., 1934, 30.c 74 GENERAL AND PHYSICAL CHEMISTRY.rotational contribution to the partition function is then given by thethree summations 21z(2K + 3 ) e - E m K W + C(2K + l ) e - & w K P T + C(2K - l ) e - E m K ) / k T .In addition to the ground state, two excited states, vix., lAg+ at 0.97e.v., and lEg+ at 1-62 e.v., above the ground level, must be con-sidered; the former 21 has a noticeable effect only at 1000" Abs.,and the latter 22 a t 2500" Abs.If a diatomic molecule has two dissimilar nuclei, having spinsis and ifs, the nuclear-spin factor, by which the 2J + 1 value forevery level is to be multiplied, is (2i, + 1 ) ( 2 i : + 1) to obtain thecomplete rotational statistical weight.For a 1Z molecule, theapplication involves no complications, but where other types ofground terms have to be considered the necessary factors must beincluded. Nitric oxide in itseground state is Qi7; (Hund's case-acoupling), with a frequency separation of about 120 cm.-l, whichis too large to be ignored; for the lower level the smallest value ofJ , here also the effective rotational quantum number, is 8, whereasfor the upper level it is G, subsequent values increasing in steps ofunity.Except in C states, each rotational level is split into twoslightly separated sub-levels, the phenomenon being known as A-typedoubling.23 The frequency separation of the doublet is generallyso small that the energies may be regarded as identical, so that theeffect is merely to double the statistical weights. The completerotational partition function for nitric oxide is thus : 24B = l , 3 , 5 . . . K = 1 , 3 , 6 . . . K = l , 3 , 6 . . .2 x 3C(2J + l)e-"JkT + 2 x 3 C ( 2 J + 1 ) e - Y k rwhere 2 and 3 are the A-type doubling and the nuclear-spin factor,and E J and E; refer to the energies in the 211t and the 2flG state,respectively, for various values of J .At 298.1" Abs., no more thanthree values of J need to be included in each sum.The hydroxyl radical has an inverted 211 ground term, so that the2II: is lower than the 211* level; the separation of rotational statesinto A and B sub-levels, due to A-type doubling, is unusually large,and so, except a t high temperatures, it is not sufficient merely todouble the statistical weights as is the case with nitric oxide. Therotational partition function is therefore obtained as the sum offour 2C(2J + l)e-EJ/kT terms, with different sets of EJ values for the21 H. L. Johnston and M. K. Walker, J . Amer. Chem.~Soc., 1933, 55, 172;A . , 1933, 229.22 Jdem, ibid., 1935, 57, 682; A., 690.z3 W. Jevons, op. cit., p. 126.24 H. L. Johnston and A. T. Chapman, t7. Amer. Chem. SOC., 1933, 55,J = l 3 5 2 ) '13 '1 . . . J = l 'I 'I 2, 2 , '1 . . .153, 229QLASSTONE : DETERMINATION OF THERMODYNAMIC CONSTANTS. 75A and B rotational levels of each constituent of the d0ublet.2~The factor 2 is the nuclear-spin contribution, since is is Q for hydrogen,and zero for oxygen.Since the cyanide radical has a 2C. ground term, there is noA-type doubling, although every rotational level is a duplet. Thevalue of J for one set (P,) is equal to K -t Q, and for the other (F2)it is K - Q, where K , the rotational quantum number, can haveany integral value, including zero ; when K = 0, however, the corre-sponding F2 level is missing.The p values of the P, and F2 seriesare, therefore, 2K + 2 and 2K, respectively, each being then multi-plied by the nuclear-spin factor 3, since the spins of the carbon andnitrogen nuclei are 0 and 1, respectively. The complete rotationalpartition function 26 for this radical is consequently3C(2K + 2)e-c~(m’kp + 3C.2Ke-Em~dk(rK = 0 , 1 , 2 , 3 . . . K = l , 2 , 3 . 4 . . .Energy Values.-In the early applications 27 of the partitionfunction for the determination of fhermodynamic constants, theenergies of the rotational levels were calculated from the actualfrequencies of the spectral lines of the molecules concerned, thelowest rotational level in the v = 0 vibrational band being taken asthe zero point.Recent analyses of band spectra, however, havepermitted the expression of the frequencies of the lines of a givenelectronic level, for diatomic molecizles, in the form of equations ofthe type 28v = VO + ae(v + Q) - xoe(v + Q)2 . . + B J ( J + 1) + D , J ~ ( J + i ) 2 + P,J~(J + 113 . . (18)where vo is the electronic frequency-separation, we the equilibriumvibration frequency, x the anharmonic vibration constant, and vand J (sometimes K ) are the vibrational and rotational quantumnumbers, respectively. The factors B, and D, vary with the vibra-tional level according to the relationshipsB, = Be - a(v + 8) -t y(v + $)2 . . .Dv = De + p ( ~ + Q)2 + 6(v + i)4 . . .Be, De, and a, p, 7,. and 6 being constants for the electronic level,which are determmed from the observed spectral frequencies.The quantity F, also depends on v, but as it is in any case very small,25 H.L. Johnston and D. H. Dawson, J . Amer. Chem. SOC., 1933, 55, 2744;A., 1933, 1005.26 Cf. F. A. Jenkins, Y. K. Roots, and R. 8. Mulliken, Phyaical Rev., 1932,39, 16; A., 1932, 145; see H. Zeise, 2. Ellektrochem., 1933, 39, 899.27 H. C. Hicks and A. C. G. Mitchell, loc. cit., ref. (4); W. F. Gianque andR. Wiebe, J . Amer. Chem. Soc., 1928, 50, 101; A., 1928, 228.28 W, Jevons, op. cit., Chap. 1176 GENERAL AND PHYSICAL CHEMISTRY.it may be assumed constant. The purpose of the correction factorsis to allow for changes in the moment of inertia of the molecule indifferent vibrational levels, and for the interaction of vibrationaland rotational energies.For a rigid molecule in which there is nointeraction D, and Fv are zero, and B, is constant and equal toh2/8x21, where I is the moment of inertia. By means of theseequations the frequencies of all the rotational lines can be calculatedand hence the total internal energy, including electronic and vibra-tional energy, of the corresponding levels can be determined; thevalue of E to be used in the partition function Q is then obtained bysubtracting the energy for the lowest level (v = 0, J = 0) in theground state, i . e . , the zero-point energy, (&me - &xoe)hc." Whenspectroscopic measurements are relatively limited, it is often possibleby means of the frequency equations to determine, with fair accuracy,the energies of levels giving rise tjo bands beyond the limit of actualexperimental observation ; such energies have frequently to beused in the calculation of thermodynamic quantities.Xurnrnation.-In the determination of &, the rotational portion,using the appropriate energies and statistical weights, is first deter-mined by summing the series for all possible rotational levels(see above) in the v = 0 vibrational level, for the ground state ofthe molecule.The process is then repeated for the v = 1, 2, 3,etc., levels, as long as they contribute appreciably to the partitionfunction. The same process is then carried out for every electronicstate of relatively low energy separation, and the various sumsadded to give the complete state sum.Since the separations ofsuccessive rotational levels are relatively small, it is evident that,except a t very low temperatures, such levels will contributeappreciably to the total partition function until high rotationalquantum numbers are attained. With nitric oxide, for example,the rotational contribution becomes negligible only after 81 levels,in the v = 0 state, a t 1000" Abs., and 168 and 200 levels must beincluded at 2000" and 3000" Abs., re~pectively.~4 It is evident,therefore, that the process of summation may become very tediousa t high temperatures, where several vibrational, and possiblyelectronic, states must be included. Various methods have beenemployed for simplifying the labour involved : by means of appro-priate frequency equations, of the type of equation (18), the internalenergy is expressed in the form of asymptotic series of exponentialterms, and summation is replaced by integration; provided thetemperature is not too low, the error involved in the determination ofQ is negligible.The method in its simplest form was first used for* The equation (18) for the frequency of spectral lines can be expressed insuch a form as to give the required energy c directlyGLASSTONE : DETERMINATION OF THERMODYNAMICJ CONSTANTS. 77rigid diatomic molecules,29 and was later modified 30 to allow fornon-rigidity in molecules having ground terms. It permittedthe determination of the rotational partition function for a givenvibrational state by summing a small number of terms in a series :the calculation had to be repeated for each vibrational level con-tributing materially to the total sum.Since the evaluations ofentropy and heat capacity require a knowledge of the first and secondderivatives of Q [equations (6) and (S)], these have also been expressedas a similar series which can be summed quite readily.31 If manyvibrational levels have to be taken into account, then the summationis still laborious, although the work can be simplified by utilisingthe observation that the rotational function &rot., and its derivativesdQ,,,,./dT and d2Qrot./dT2, for one vibrational level v bear a constantratio to the values for the v + 1 level.31 Further developments 32have eliminated even this summation, and have permitted theapplication of the mathematical methods to determine completepartition functions of 211 and 3X diatomic molecules,33 and evenof polyatomic non-linear molecules (see below).By means of suit-able tables, based on the formuh derived, the labour involved inthe calculation has been considerably diminished. These tables,and formulze, apply only t o unsymmetrical molecules in which thereis no alternation in the statistical weights of odd and even levels, andthey do not allow for nuclear spin: allowance can be made forboth these factors, as will be seen later (p. 78).Approximation Methods.Tf the different forms of internal energyof a molecule can be regarded as independent, the complete partitionfunction can be taken as equal to the product of electronic, vibrational,and rotational functions, QVik,,., and &rot., respectively, whereQel.= Cpel.e-EeI./kp ; Qvib. = Cpdb.e-Edb.lk* ; Qrot. = Cprot.e-erot-/krand the complete partition functionQ = &el. X &vib. X Qrot.In evaluating the separate terms, pel. may be taken as equal to themultiplicity of the particular electronic state, provided the energy39 H. P. Mulholland, Proc. Camb. Phil. Soc., 1928, 24, 280; G. B. B. M.Sutherland, ibid., 1930, 26, 402; A., 1930, 1244.80 W. F. Giauque and R. Overstreet, Zoc. cit., ref. (13) ; L. S. Kassel, J .Chem. Physics, 1933, 1, 576; A., 1934, 31.31 H. L. Johnston and C. 0. Davis, J . Amer. Chem. Soc., 1934, 56, 271;A., 1934, 354.33 A. R. Gordon and C. Barnes, J .Chern. Physics, 1933, 1, 297; A., 1934,31; L. S. Kessel, loc. cit., ref. (30); Phyaicd Rev., 1933, 43, 364.33 A. R. Gordon and C. Barnes, Zoc. cit.; L. S. Kassel, Zocc. cit.; E. E.Witmer, J. Chem. Physics, 1934, 2, 618; A , , 1934, 1165; see also C. Gregory,8. Physik, 1932, 78, 791; A., 1933, 1675 GENERAL AND PHYSICAL CHEMISTRY.of separation of the multiplets is not large, and the correspondingenergy of the level above the ground state, determined from thevalue of v0 in equation (18). In the Qvjb. term, (pvib. is alwaysunity for a diatomic molecule; &vib. may be taken as being the samein all electronic levels, and equal to ~ C C G ~ Z I above the zero-pointenergy, neglecting the anharmonicity constant, where oo is theequilibrium frequency in the ground state.The vibrationalpartition function is thus given by the expression(1 - e--7ccwo/kP 1 Qvib. = Ce-hWovlkf = W 1-v = oSince the rotational and vibrational energies are assumed independ-ent, the molecule may be taken as rigid and the moments of inertiaconstant ; the rotational energy of such a 1C diatomic molecule maythen be written J ( J + l ) h 2 / 8 ~ 2 1 , and consequentlywhere G = h2/8x21kT. In this equation the nuclear-spin factor isneglected, and it is also assumed that the molecule is heteronuclear,so that there is no alternation in the p values for successive rotationallevels, If 0 is small, i.e., for relatively high temperatures, andespecially for molecules having small moments of inertia, the sum-mation can be replaced by i n t e g r a t i ~ n , ~ ~ ~ ~ ~ with the result that= 1/0.For molecules in other than l Z states, analogousapproximate values for the rotational function, applicable atappreciable temperatures, can be deduced ; if necessary, the effectof A-type doubling must be included by means of a factor 2,the frequency separation being ignored. Allowance for multi-plicity due to nuclear spin is made (p. 74) by multiplying by(2& + l)(2ifS + 1) for a heteronuclear molecule.If the molecule has two identical atoms, the effect of nuclearspin should be obtained by multiplying the odd and even terms byis(.ZiS + 1) and (is + l)(2iS + l), as already explained (p. 73).In the summation of the (2J + l)e-uJJ'J+l) terms over all values ofJ from 0 to 00 , it can be shown that, provided a be small, the sum ofthe terms for which J is even is equal to that for the terms with oddJ values.35 The inclusion of the nuclear-spin factor is consequentlyequivalent to multiplying the Qrot.obtained above by (2i, + 1)2/2;for hydrogen this correction factor is 2, for deuterium it is p, and foroxygen 8. This last result is obviously in agreement with the factthat the alternate rotational levels of oxygen are missing, and the34 L. S. Kassel, J . Amer. Chem. SOC., 1933, 55, 1351; A., 1933, 661.35 See L. S. Kassel, Zoc. cit., ref. (30)QLASSTONE : DETERMINATION OF THERMODYNAMIC CONSTANTS. 79others show no nuclear-spin degeneracy. For molecules of thistype the approximate value of &rot. becomes 1/20 : this result hadbeen previously deduced by classical mechanic^,^^ the factor 2,called the " symmetry number," representing the number of equiv-alent orientations in space which the molecule is able to occupyas a result of simple rotation.37 Since the expression for entropy[equation (7)] involves R In &, the correction for symmetry and fornuclear-spin degeneracy with a diatomic molecule is 222 In (2is + 1) -Rln2; if i, = 0, as for oxygen, this becomes - Rln2.It should be noted that the equality of the odd and even terms inthe &rot.summation is .only approached when c is small : for mostmolecules, the temperature at which this occurs is quite low, butwith equilibrium hydrogen and deuterium it is not the case. Withthese substances 38 it only applies when the ratio of ortho- to para-forms has attained the values of 3 : 1 and 1 : 2, respectively, and thisis only the case at about 273" Abs.for hydrogen and a t 200" Abs.for deuterium. For " normal " hydrogen and deuterium theapproximations described are, of course, applicable. With otherhomopolar molecules possessing nuclear spin, the " normal " ratioof ortho- and para-states is reached at such low temperatures thatunder reasonable conditions the summation and correction factorsconsidered above are adequate.If the partition functions are required for the calculation ofequilibrium constants, then provided the temperatures are suchthat the approximations discussed are valid, it is permissible t oomit the nuclear-spin factor, both from atoms and molecules,although the '' symmetry number " must be included.39 Sincenuclear spins are not always known, it is customary to quoteentropy and Po - 8," values with the spin-multiplicity effectomitted, but with due allowance for symmetry; in fact, theseallowances must be made if the entropy values from spectroscopicdata are to be used in conjunction with others determined fromthermal measurements.These entropies have been called " virtual "entropies,40 and given the symbol S* ; if absolute values are required,36 Cf. P. Ehrenfest and V. Trkal, Zoc. cit., ref. (1).37 For full discussion, see J. E. Mayer, S . Brunauer, and M. G. Mayer, Zoc.cit., ref. (11).See W. F. Giauque, Zoc. cit., ref. (12); H. L. Johnston and E.A. Long,Zoc. cit., ref. (15).39 G. E. Gibson and W. Heitler, 2. Physik, 1928, 49, 465; H. Ludloff,ibid., 1929, 57, 227; W. F. Giauque and R. Overstreet, Zoc. cit., ref. (13);J. E. Mayer et al., Zoc. cit., ref. (11); see, however, H. Ludloff, 2. Physilc,1931, 68, 433; A., 1931, 675; D. 5. Villnrs, Physical Rev., 1931, 38, 1563.40 Idem, ibid., p. 1552; A., 1932,14; R. M. Badger and S.-C. Woo, J. Arner.Chem. SOC., 1932,54,3523; A . , 1932, 120580 GENERAL AND PHYSICAL CHEMISTRY.a factor R In (2i, + 1) must be added for every atom of spin is in themolecule.Isotope E#ect.-For substances containing isotopic forms, accuratespectroscopic data are generally available only for the moleculecontaining the predominant isotope ; the corresponding values forother forms can be readily calculated, however, by assuming thebinding forces between atoms to be independent of their isotopicnature.In the determination of the entropy of the normal mixturethe entropies of the separate forms are multiplied by their respectivemo1.-fractions, determined from the isotopic and chemical atomicweights, and the results are added, the entropy of mixing beingincluded. Thermally determined entropies do not involve thisfactor, and for use in conjunction with these, for calculation ofequilibrium constants, the entropy of mixing is omitted : if this isdone, then in the appropriate instance it is necessary also to neglectthe fact that the statistical weight of a heteronuclear molecule,e.g., C135C137, is double that of the symmetrical molecules, C135C135and C137C137.The same result, at least for chlorine, may be obtainedin a simpler manner by treating the substance as a homonuclearmolecule, each atom having an atomic weight 35.46, the energy ateach level being obtained by giving the proper proportional weightst o the corresponding levels for the three types of isotopic molecules ;this effect is believed to be general and to apply to all analogous~ases.4~ Hydrogen chloride may be treated as a mixture of definiteamounts of HCP5 and HCP7, although the entropy of mixing andthe nuclear-spin effect must not be included if the results are to beused in conjunction with thermal values.Polyatomic MoZecuZes. *-With such molecules precise calculationsare very difficult, partly because the spectra are complex anddifficult to analyse, and partly because of the labour involved inthe evaluation of the partition function when three, or more,moments of inertia and several types of vibration have to be con-~idered.4~ By replacing summation by integration and using41 W.F. Giauque and R. Overstreet, loc. cit., ref. (13); W. G. Brown, ibid.,1932, 54, 2394; A., 1932, 906; A. R. Gordon and C. Barnes, J . PhysicalChem., 1932, 36, 2292; A., 1932, 997.42 F. Hund, 2. Physilc, 1927, 43, 805; A., 1927, 809; W. Elert, ibid., 1928,51, 6 ; A., 1929, 11; D. S. Villars and G. Schultze, Physical Eeu., 1931, 38,998; A., 1931, 1216; D. S. Villars, ibid., p. 1552; A . , 1932, 14; D. P. Mac-Dougall, ibid., p. 2074; D. M.Dennison, ibid., 1932, 41, 304; A . , 1932, 982;A. AdelandD. M. Dennison, ibid., 1933,43,716; 44,99; A., 1933, 661, 885;Dennison, Rev. Mod. Physics, 1931, 3, 280; H. R. Nielsen, Physical Rev.,1932, 40, 445; T. E. Sterne, ibid., 1932, 39, 993; 42, 556; A., 1932, 666;1933, 118; D. S. Villars, Chem. Reviews, 1932, 11, 369; E. B. Wilaon, J .C‘hem. Physics, 1935, 3, 276; A., 810.* See report on “ Spectroscopy,” p. 53GLASSTONE : DETERMINATION OF TIIERMODYNAMIC CONSTANTS. 81methods of asymptotic e~pansion,~:~ it has been possible to diminishthe labour involved in obtaining the Q sum for relatively simplepolyatomic molecules, e.g., HCN, GO,, N20, C2H2, H20, SO,, CH,,and CD,, due allowance being made for anharmonicity and forstretching and interaction terms.In most cases, however, thesimplification is made of treating the molecule as rigid and ofassuming the different forms of energy to be independent : thecomplete partition function is then the product of the separateelectronic, vibrational, and rotational functions. At relativelyhigh temperatures the errors involved in these assumptions aregenerally small.The classification of polyatomic molecules according to theelectronic configuration of the ground state is only possible for arelatively limited number of substances which behave as quasi-diatomic ; in other cases it is assumed that there is only one electronicground level and that excited levels do not contribute to the totalstate sum. The electronic factor in the partition function is thusgenerally, unless there is direct evidence to the contrary, taken asunity.A molecule containing n atoms has in general 3n - 6 normal modesof vibration : for a linear molecule this is increased t o 3n - 5, andis decreased t o 3n - 7 for a molecule of the ethane type because ofinternal rotation.Of this total, n - 1 are stretching (valency),the others being bending (deformation) vibrations. If the energyof the vibrational levels 44 can be expressed in terms of a formulasimilar to the one used for diatomic molecules, it is sometimespossible t o make a reasonably accurate estimate of the vibrationalpartition function.45 For a complex molecule it is generally thepractice t o use for each type of vibration the approximate relation-ship obtained for a diatomic molecule, vix., Qyib. = (1 - e-hcoi'kr )- 1 :the vibrational function for the whole molecule is given by theproduct of these terms, one for every possible vibrational mode.46If any of the frequencies are degenerate, due allowance must bemade in the product, the corresponding term being included foreach component of the degenerate frequency.The vibrational43 A. R. Gordon, J . Chem. Physics, 1934, 2, 65; 1935, 3,259; A., 1934,355 ;1935, 811; I. E. Viney, Proc. Comb. Phil. SOC., 1933, 29, 142, 407 (correction);A., 1933, 206; L. S. Kassel, Eocc. cit., ref. (30), (34); J . Chern. Physics, 1935,3, 115; A., 437.** Cf. D. M. Dennison, Rev. Mod. Physics, 1931, 3, 280.45 L. S. Kassel, J. Arner. Chem. SOC., 1934, 56, 1838; A., 1934, 1300;R.W. Blue and W. F. Giauque, ibid., 1935,57,991; A., 924.46 See B. Topley and H. Eying, J . Chem. Physics, 1934, 2, 217; S., 1934,851 ; R. H. Crist and G. A. Dalin, ibid., p. 735 ; A., 1935,33 ; E. Teller and B.Topley, J . , 1935, 876; A , , 107682 GENERAL AND PHYSICAL CHEMISTRY.terms affect the complete Q value to a relatively small extent,except at high temperatures; 47 e.g., at 298" Abs. Qrot. for nitrousoxide is 496, whereas Qvib. is 1.1 ; the introduction of approximationmethods and the use of uncertain frequencies consequently resultin relatively small errors. The rotational factor is the more im-portant, and this may best be considered under the headings ofdifferent types of molecules.The rotationalenergy, at least in the lower vibrational levels, may be expressed bythe same formula as for a diatomic molecule,48 although this is notstrictly accurate.,*, 49 The moments of inertia being relativelylarge, it is permissible to replace summation by integration, and theapproximation already described (p. 78) may be used.For amolecule possessing symmetry, the appropriate symmetry factors must be introduced, giving Qrot. = 1/80, thus allowing for missinglevels. The value of I required to calculate t~ is generally obtainedfrom spectroscopic data, although it may be evaluated from theinteratomic dimensions if they are known. The result does notinclude the nuclear-spin factor, for which allowance need only bemade if the Q is required to calculate absolute entropy.Xphericul rotator (e.g., CH,, CCl,, but not CMe, because of freerotation). Molecules possessing tetrahedral symmetry may betreated as spherical rotators having three equal moments of inertia :the rotational energy may be expressed by the same equation as fora diatomic molecule.From quantum-mechanical considerations,it is sometimes possible to allow for the statistical weights of differentrotational levels, but if missing levels and nuclear-spin effects areignored, each level has a p value of (2J + 1)2 ; replacing summationby integrationYm then at appreciable temperatures Qmt. = +/st~3/2.The term t~ has the same significance as previously (p. 78), I beingassumed constant, and s is the symmetry number,51 vix., 12 forCH, and CC14, which allows for missing levels.The nuclear-spinfactor is not included.Xyrnrnetrical top. Under this heading may be considered twotypes of molecule : (a) single pyramidal, e.g., NH,, CHCl,, or ( b )double pyramidal, e.g., C,H,. I n molecules of this nature, two ofthe three moments of inertia are identical, I* = IB > Ic. Forthe single-pyramid type the rotational energy, assuming a rigidLinear molecuEes (e.g., HCN, N,O, CO,, C,H,).47 R. M. Badger and S.-C. Woo, loc. cit., ref. (40), p. 3527.4 * R. M. Badger and S.-C. Woo, loc. cit., ref. (40).49 L. S. Kassel, loc. cit., ref. (45).m H. P. Mulholland, loc. cit., ref. (29) ; L. S. Kassel, toc. cit., ref. (34).61 See J. E. Mayer et at., loc. cit., ref. (11); A. R. Gordon and C. Barnes,J . Physical Chem., 1932, 36, 2601; A ., 1932, 1203GLASSTONE : DETERMINATION OF THERMODYNAMIC CONSTANTS. 83molecule, may be written 52 in the form given on p. 55, whereK can have a series of 2J + 1 values, vix., J, J - 1 , . . . , 0, . . .- J + 1, - J , for every value of J . The multiplicity of eachrotational level is 2J + 1, but owing to the introduction of K eachlevel is (2J + 1)-fold degenerate. The application of the usualapproximation methods 53 leads to Qrot. = x ~ ’ ~ / Q G ~ c T # ~ , where CTA andoc involve I* and Io, respectively. Complete analysis, with fullallowance for statisticalweights, etc. , gives results very little different.For an ethane-like top, the rotational-energy equation is similarto that for the single pyramidal molecule, another term involvingK’ equal to K & 2n, where n is an integer, being included; 54 theapproximate value 55 of &rot.is then found to be X / S G A C T ~ .For the general case in which the moleculeis non-linear and has three different moments of inertia, the rotationalenergy cannot be expressed by a simple formula : the energies of thelower levels may be represented by a complex relationship 56 whichhas been actually used to calculake & for the water molecule.57A satisfactory approximation,53 at appreciable temperatures, assum-ing a rigid molecule, is obtained by substituting I A I B for Ia2 in theequation for a pyramidal moleciile, thus &rot. = ( ~ / O A . C T B ~ C ) ~ ’ ~ / ~ .For a planar molecule, e.g., H20 or C6H,, IA +- IB = 10; forH20, s = 2; for C,H6, s = 12; and for cyclohexene, 8 = 2, sinceit is non-planar.Complex Molecules.-By analogy with the formulae already given,it has been deduced 58 that for a molecule with several rotatingpartsAsymmetrical top.I*, IB, Ic .. . being the moments of inertia of the molecule andof its independently rotating parts; a, b, c . . . are the rotationaldegrees of freedom associated with the corresponding moments ofinertia, their sum being equal to n, the total number of rotationaldegrees of freedom; and s is the symmetry number, defined as thenumber of indistinguishable permutations produced by rotation ofthe molecule or of its parts. This relationship has been applied toG2 F. Reiche, 2. Physik, 1926, 39, 444; J.E. Mayer et al., loc cit., ref. (11).53 L. S. Kassel, Zoc. cit., ref. (34); A. R. Gordon, loc. cit., ref. (43); for54 H. R. Nielsen, Zoc. cit., ref. (42); J. E. Mayer et. al., loc. cit., ref. (11).5 5 I d e m , ibid.56 H. A. Kramers and G. P. Ittmann, 2. Physik, 1930, 58, 217; D. M.5 7 A. R. Gordon and C. Barnes, J. Physical Chem., 1932, 36, 1143; A.,68 J. 0. Halford, J. C’hem. Physics, 1934, 2, 694; A., 1934, 1300.classical treatment, see A. Eucken, Physikal. Z., 1929, 30, 818.Dennison, Zoc. cit., ref. (44).1932, 69684 GENERAL AND PHYSICAL CHEMISTRY.calculate the entropies of methyl alcohol, methyl ether, toluene,acetone, isobutane, P-methyl-AP-butene (CMe2:CHMe), and neo-pentane. The problem of complex molecules has also been examinedfrom a more fundamental point of view 59 which appears to haveconsiderable promise, especially in its application to normal paraffinhydrocarbons .GOSince in all the approximation methods the nuclear-spin factorhas been neglected, the partition function should be multiplied byZi, + I for every nucleus if absolute entropies are required; forthe calculation of dissociation constants or for combination withcalorimetric data this correction should not be applied.Applications.-The methods outlined above have been used inthe calculation of thermodynamic functions, e.g., entropy, heatcapacity, and the free-energy function, (Po - Eoo)/T, for the follow-ing molecules : hydrogen,62 hydrogen deuteride deuter-oxygenYs5 ozone,66 hydroxyl radical,67 water,68 methane,6959 M.L. Eiciinoff and J. G. Aston, J . Chem. Physics, 1935, 3, 379; A.,6o L. S . Kassel, private communication.For atoms, see refs. (12)-(15).62 D. M. Dennison, Proc. Roy. Xoc., 1927, [A], 115, 483; A., 1927, 817;R. H. Fowler, ibid., 1928, [A], 118, 52; A., 1928, 469; T. E. Sterne, ibid.,1931, [A], 130, 367; 133, 303; A., 1931, 295, 1222; F. Hund, 2. Physik,1927, 42, 93; A., 1927, 495; S. Daumichen, ibid., 1930, 62, 414; A., 1930,982; W. F. Giauque, loc. cit., ref. (12); C. 0. Davis and H. L. Johnston,ibid.,1934, 56, 1045; A., 1934, 722; A. R. Gordon and C. Barnes, J . PhysicalChem., 1932,36, 1143; A., 1932, 695; see also R. H. Fowler and T. E. Sterne,Rev. Mod. Physics, 1932, 4, 635.1064.63 H. C. Urey and D. Rittenbcrg, loc.cit., ref. (19).64 Idem, ibid. ; H. L. Johnston and E. A. Long, loc. cit., ref. (15); H. Motzand F. Petat, Monatsh., 1934, 64, 17; A., 1934, 480; K. Clusius and E.Bartholom6, 2. Elektrochem., 1934, 48, 524; A., 1934, 951 ; 2. physikal.Chem., 1935, [B], 30, 258.6 5 W. F. Giauque and H. L. Johnston, J . Amer. Chem. Xoc., 1929, 51,2300; A., 1929, 1137; H. L. Johnston and M. K. Walker, Zoc. cit., ref. (21);ibid., 1935, 57, 682; A., 690; B. Lewis and G. von Elbe, ibid., 1933, 55,511; 1935, 57, 1399; A., 1933, 343, 1198; A. R. Gordon and C. Barnes,J. Physical Chem., 1932, 36, 2292; A., 1932, 997.66 L. S. Kassel, J . Chem. Physics, 1933, 1, 414; A,, 1934, 30.67 H. L. Johnston and D. H. Dawson, J. Amer. Chem. Xoc., 1933, 55,2744; A., 1933, 1005.68 A.R. Gordon and C. Barnes, loc. cit., ref. (62) ; A. R. Gordon, J . Chem.Physics, 1933, 1, 308; 1934, 2, 65, 549; A., 1934, 30, 355, 1070.69 W. F. Giauque, R. W. Blue, and R. Overstreet, Physical Rev., 1931, 38,196; D. S. Villars and G. Schultze, loc. cit., ref. (42); D. S. Villars, loc. cit.,ref. (42); D. P. MacDougall, Zoc. cit., ref. (42); T. E. Sterne, ibid., 1932, 42,556; A., 1933, 118; L. S. Kassel, loc. cit., ref. (34); A. R. Gordon and C.Barnes, J. Physical Chem., 1932, 36, 2601; A., 1932, 1203; R. D. Vold,J . Amer. Chem. Soc., 1935, 57, 1192; A., 1064GLASSTONE : DETERMINATION OF THERMODYNAMIC CONSTANTS. 86ethylene, 70 acetylene, 71 ethane, 72 benzene, 73 cycZohexene, 73 nitrogen, 7*ammonia,75 nitric oxide, 76 nitrous oxide, 77 hydrogen cyanide,78sulphur (S2),79 hydrogen sulphideY8O sulphur dioxideY8l carbon di-sulphide and oxysulpliide,81a sulphur monoxide ( SO),s2 chlorine,s3hydrogen chloride, 84 deuterium chloridejs5 bromine,86 hydrogen70 L.S. Kassel, Zoc. cit., ref. (34) ; H. A. Smith and W. E. Vaughan, J .Chem. Physics, 1935, 3, 341; A., 934; A. V. Frost, J . Gen. Chem. Russia,1934, 4, 124; A., 1934, 843.71 L. S. Kassel, Zoc. cit., ref. (34); J. E. Mayer et aZ., Zoc. cit., ref. (11);A. R. Gordon, J . Chem. Physics, 1935,3,259; A., 811.72 H. A. Smith and W. E. Vaughan, loc. cit., re€. (70); J. E. Mayer et aZ.,loc. cit., ref. (11); A. V. Frost, Zoc. cit., ref. (70).73 J. E. Mayer et al., Zoc. cit., ref. (11) ; V. Deitz and D. H. Andrews, ibid.,1933,1, 62; A ., 1933,212.74 W. F. Giauque and J. 0. Clayton, loc. cit., ref. (15); H. L. Johnston andC. 0. Davis, loc. cit., ref. (31).7 5 W. F. Giauque et al., Zoc. cit., ref. (69) ; D. S. Villars, loc. cit., ref. (69) ;D. P. MacDougall, Zoc. cit., ref. (69); T. E. Sterne, Physical Rev., 1932, 39,993; A., 1932, 566; W. M. D. Bryant, J . Amer. Chm. Soc., 1931, 53, 3014;A . , 1931, 1127.7 6 H. L. Johnston and W. F. Giauque, J . Amer. Chem. SOC., 1929, 51,3194; A., 1930, 24; H. L. Johnston and A. T. Chapman, ibid., 1933, 55,153, 5073 (correction); A., 1933, 229; R. W. Blue and W. F. Giauque, Zoc.cit., ref. (45); A. R. Gordon and C. Barnes, Zoc. cit., ref. (32); E. E. Witmer,J . Amer. Chem. SOC., 1934, 56,2229; A., 1935, 21.7 7 R. M. Badger and S.-C. Woo, Zoc.cit., ref. (40); W. H. Rodebush,Physical Rev., 1932, 40, 113; R. W. Blue and W. F. Giauque, loc. cit.,ref. (45); L. S. Kassel, Zoc. cit., ref. (45); A. R. Gordon, Zoc. cit., ref.7 8 R. M. Badger and S.-C. Woo, Zoc. cit., ref. (40); A. R. Gordon, loc. cit.,ref. (71).'* C. W. Montgomery and L. S. Kassel, Zoc. cit., ref. (15); P. C. Cross, J .Chem. Physics, 1935,3, 168; A., 569; I. N. Godnev, Phpikal. 2. Sovietunion,1935, 7, 442; A., 1312.(72).8o P. C. Cross, Zoc. cit., ref. (79).n1 A. R. Gordon, J . Chem. Physics, 1936, 3, 367; A., 1204; P. C. Cross,Ila P. C. Cross, Zoc. cit.82 C. W. Montgomery and L. S. Kassel, Zoc. cit., ref. (15).83 W. F. Giauque and R. Overstreet, Zoc. cit., ref. (13); T. E. Sterno, Proc.Roy. SOC., 1931, [A], 131, 339; A., 1931, 674; A.1%. Gordon and C. Barnos,loc. cit., refs. (32), (65) ; H. M. Spencer and J. L. Justice, J . Amer. Chem. SOC.,1934, 56, 2311; A., 1935, 21.84 W. F. Giauque and R. Wiebe, Zoc. cit., ref. (27); E. Hutchisson, ibid.,1928, 50, 1895; A., 1928, 941 ; W. F. Giauque and R. Overstreet, Zoc. cit.,ref. (13); T. E. Sterne, Proc. Roy. Soc., 1931, [A], 133, 303; A., 1931, 1222;H. M. Spencer and J. L. Justice, Zoc. cit., ref. (83) ; A. R. Gordon and C.Barnes, locc. cit., refs. (32), (65).8 5 H. C. Urey and D. Rittenberg, Zoc. cit., ref. (19).8 G A. R. Gordon and C. Barnes, Zoc. cit., ref. (32); J. Ckem. Physics, 1933,1, 692; A., 1934, 30; W. G. Brown, J . Amer. Ghem. Xoc., 1932, 54, 2394;A., 1932, 906.ibid., p. 82586 GENERAL AND PHYSICAL CHEMISTRY.bromide,*' iodine,88 hydrogen iodide,B9 deuterium iodide,g0 iodinemonochloride,gl carbon monoxide,92 carbon dioxide,93 chloro-methane~,~4 the tetrachlorides of carbon, silicon, titanium, andarsenic and phosphorus trichl~rides,~~ arsenic g6 and phosphorustri ff uorides , p hosp hine,97 sulphur hexafluor ide , 98 nickel carb ony 1, 99methyl alcohol, dimethyl ether, acetone and various hydrocarbon^.^^Equilibrium constants 1 have been evaluated for the followingreactions : H, e 2H;2 D, =+= ZD; HD H + D;2HD =s= H, -t D2;4 0, 2 0 ; 0, =+= 0, + 0 ; H20 =+H, + 40,; 7 H,O &H2 + OH; 7 H,O + D20 G+ 2HDO;;HDO + H, HZO + D2; 9 D2O + H, H2O + D,; '0 N28 7 W.F. Giauque and R. Wiebe, J . Amer. Chem. SOC., 1928, 50, 2193; A . ,1928, 1083; A.R. Gordon and C. Barnes, Zoc. cit., ref. (32).88 W. F. Giauque, ibid., 1931, 53, 507; A . , 1931, 429.8f) W. F. Giauque and R. Wiebe, ibid., 1929,51, 1441; A . , 1933, 755.91 J. M. McMorris and D. M . Yost, ibid., 1932, 54, 2247 ; A., 1932, 906.92 J. 0. Clayton and W. F. Giauque, ibid., 1932, 56, 2610; 1933, 57, 5071(correction); A . , 1932, 906; L. S. Kassel, J . Chem. Physics, 1933, 1, 576;A . , 1934, 31 ; H. L. Johnston and C. 0. Davis, Zoc. cit., ref. (31) ; A. R. Gordonand C. Barnes, Zoc. cit., ref. (32).93 R. M. Badger and S.-C. Woo, Zoc. cit., ref. (40); L. S. Kassel, Zoc. cit.,ref. (45); H. M. Spencer and J. L. Justice, Zoc. cit., ref. (83); A. R. Gordon,J . Chem. Physics, 1933, 1, 308; A., 1934, 30.H. C. Urey and D. Rittenberg, Zoc.cit., ref. (19).94 R. D. Vold, Zoc. cit., ref. (69).95 D. M. Yost and C. Blair, J . Amer. Chem. SOC., 1933, 55, 2610; A., 1933,g6 D. M. Yost and J. E. Sherborne, J . ClLem. Physics, 1934, 2, 125; A . ,97 D. M. Yost and T. F. Anderson, ibid., p. 624; A., 1934, 1289.g8 D. M. Yost, C. C. Steffens, and S . T. Gross, ibid., p. 311; A., 1934, 830.Qg A. B. F. Duncan and J. W. Murray, ibid., p . 636; A . , 1934, 1289.784.1934, 473.For tabulated summaries, see H. Zeise, 2. EZektrochem., 1934, 40, 885 ;W. F. Giauque, Zoc. cit., ref. (12); re-calculated by H. Zeise, Zoc. cit.,H. L. Johnston and E. A. Long, Zoc. cit., ref. (15); ibid., 1934, 56, 710H. C. Urey and D. Rittenberg, Zoc. cit., ref. (19) ; F. Patat and H. Hoch,H. L. Johnston and M.K. Walker, Zoc. cit., ref. (14); G. von Elbe andL. S. Kassel, J . Chem. Physics, 1933, 1, 414; A., 1934, 30.A. R. Gordon, loc. cit., ref. (93).B. Topley and H. Eyring, Zoc. cit., ref. (46).R. H. Crist and G. A. Dalin, ibid., 1934, 2, 442, 548 (correction); A.,1934, 962, 1070; T. Forster, 2. p h y s i h l . Chem., 1934, 27, [B], 1 ; A . , 1935,33 ; see also, L. Farkas and A. Farkas, Trans. Paraday SOC., 1934, 30, 1071 ;A., 1935, 33.lo B. Topley and H. Eyring, Zoc. cit., ref. (46) ; R. H. Crist and G. A. Dalin,Zoc. cit., ref. (46).B. Lewis and G. von Elbe, J . Amer. Chem. SOC., 1935,57,612.ref. (1).(correction).Monatsh., 1934, 64, 229; A., 1934, 1153.B. Lewis, Zoc. cit., ref. (14)GLASSTONE : DETERMINATION OF THERMODYNAMIC CONSTANTS, 872N;ll NO =+ N + 0 ; 1 2 NO s *N2 + Q02;11 N,O Ge=N, + $0,; l3 c + CO, _-I 2co ; l 3 , l4 2c0, * 2co t o , *CO =+= C + &O,; l5 CO, + H, s CO + H,O; 13,16 C + 2H,+= CH4; '7 2C + 2H2 -+ C2H4 ; l7 2C + H2 =+= C,H,; 1.8C2H4 + H2 C 2 H 6 ; l9 CH, + 2H2O T+ CO2 + 4H2 ; 2o S2C1; 21 HC1 e QH, + QC12 ; 21 Br, =+= 2Br ; 22 HBr =s= QH, ++Br,;22 I, + 21;23 HI + iH2 + IBr =+ QI, + QBr;25ICl 41, + QC12; 26 H, + 2DC1 D, + 2HCI; 27 H, + 2DID, + 2HI ; 27 2C1, + 2HzO s 4HC1+ 0 2 ; 28 P2 +=2 ~ ; 2 9 S, =+= 2s; 82 SO + Q S ~ + Q0,; 82 SO, s= QS, + 0,; 30SO, SO + 40,; 30 3H, + SO, G H,S + 2H,O; 2C0, +$3, += 2CO + SO,; COS +H,S z+= CS, + H,O; CO + $3, COS; 2COS CO, 4-CS, ; CS, =+= C + S,; 81a and various interchange reactionsinvolving the isotopes of lithium, carbon, oxygen, nitrogen, chlorine,and br0mine.~1Discrepancies.-In general, there is excellent agreement betweenthermodynamic functions calculated from spectroscopic data andthe values obtained by direct experiment : in a few cases there are,l1 W.F. Giauque and J. 0. Clayton, Zoc. cit., ref. (15); recalculated by H.GO, f- H2S GS COS + H,O;Zeise, Zoc. cit., ref. (1) (p. 886).H. Zeise, loc. cit., ref. (1) (p. 886).l2 H. L. Johnston and A. T. Chapman, Zoc. cit., ref. (76);l3 L. S. Kassel, Zoc. cit., ref. (45).l4 A. R. Gordon, Zoc. cit., ref. (93); A. R. Gordon and C.l5 J. 0. Clayton and W. F. Giauque, Zoc. cit., ref. (92).l6 A. R. Gordon, Zocc. cit., ref. (68); A. R. Gordon and C.l7 L. S. Kassel, Zoc. cit., ref. (34); A.R. Gordon and C.la L. S. Kassel, Zoc. cit., ref. (34).ref. (69).ref. (62).ref. (69).recalculated byBarnes, loc. cit.,Barnes, Zoc. cit.,Barnes, Zoc. cit.,l9 H. A. Smith and W. E. Vaughan, Zoc. cit., ref. (70); A. V. Frost, Compt.rend. Acad. Sci. U.R.S.S., 1933, 4, 161 ; A., 1934, 254; see also E. Teller andB. Topley, loc. cit., ref. (46).2o A. R. Gordon and C. Barnes, Zoc. cit., ref. (69).21 W. F. Giauque and R. Overstreet, Zoc. cit., ref. (13).22 A. R. Gordon and C. Barnes, J . C'hem. Physics, 1933,1,692 ; A., 1934, 30.23 G. E. Gibson and W. Heitler, Zoc. cit., ref. (39) ; H. Zeise, Zoc. cit., ref.24 H. Zeise, loc. cit., ref. ( l ) , p. 887.25 Idem, 2. Elektrochem., 1935, 41, 267; A . , 702.2 6 J. McMorris and D. M. Yost, Zoc.cit., ref. (91); H. Zeise, Zoc. cit., ref. (l),27 H. C. Urey and D. Rittenberg, Zoc. cit., ref. (19).28 A. R. Gordon and C. Barnes, Zoc. cit., ref. (65).29 H. Zeise, Zoc. cit., ref, ( l ) , p. 888.30 A. R. Gordon, J . Chem. Physics, 1935, 3, 336; A., 1204.31 H. C. Urey and L. J. Greiff, J . Amer. Chem. Soc., 1935,457, 321; A., 446.(1) p. 887.p. 88888 GENERAL AND PHYSICAL CHEMISTRY.however, outstanding discrepancies which require consideration.The statistical entropy of hydrogen is 33.98 units, including thenuclear-spin contribution, compared with the accurate thermalvalue of 29.6-29.7 a t 298.1" Abs. : 32 there has been some contro-versy 33 over this difference, but it is now accepted as being dueto the persistence of rotation in the s0lid,~4 so that the thermalmethod, based on the third-law assumption of zero entropy, isincorrect.The calculated error, 4.39 units, is in excellent agree-ment with the observed discrepancy of 4.3-4.4 units. The correct(virtual) entropy of hydrogen to be used in conjunction with thevalues for other substances is obtained by subtracting R In 4, thenuclear-spin correction, from 33-98, giving 31.23 units. A similardifference exists between calculated and thermal entropies of deuter-ium, the values being 38.98 and 33.9, respectively : 35 this agreesexcellently with the calculated discrepancy (5.09 units). Thevirtual entropy of D2 is 38.98 - R In 9 (the nuclear-spin effect),giving 34.62 units a t 298.1" Abs. The calculated entropy of nitricoxide is about 0.75 greater than the thermal value : 36 since thisdifference is approximately +B In 2 it has been attributed to thepresence of N,O, in the solid, which exists either 36 in two formswith different coupling energies, or37 in a single form possessingtwo different possible orientations distributed at random.Fornitrous oxide the experimental value is 1.14 less than that obtainedfrom spectroscopic data : if in the solid the nitrous oxide moleculescould be oriented in a random manner either as NNO or ONN, thecrystal would possess an entropy of 1.38 instead of zero. If theorientation were not completely random, the discrepancy might besomewhat less than this amount.37 A discrepancy of the same order,1.1 units, for carbon monoxide has been attributed to a similarrandom, possibly not complete, arrangement of CO and OC in thecrystalline state.3* There also appears to be some difference betweenthe experimental and calculated entropies of water : this might wellbe due to the persistence of rotation in ice at temperatures as low32 W.F. Giauque, J. Arner. Chem. SOC., 1930,52,4816; A., 1931,294.33 H. L. Johnston and W. F. Giauque, ibid., 1928, 50, 3221; A., 1929,138; R. H. Fowler, loc. cit., ref. (62); R. H. Fowler and T. E. Sterne, loc. cit.,ref. (62); W. H. Rodebush, Proc. Nat. Acad. Sci., 1929, 15, 678; A., 1929,127; Physical Rev., 1931, 37, 221; D. MacGillavry, ibid., 1930, 36, 1398; A.,1931, 31 ; W. F. Giauque, ibid., p. 1592; loc. cit., ref. (31) ; W. M. D. Bryant,loc. cit., ref. (75).34 L.Pauling, Physical Rev., 1930, 36, 43; A., 1930, 1357; see also R. H.Fowler, Proc. Roy. SOC., 1935, [ A ] , 151, 1.35 K. Clusius and E. Bartholome, 2. physikal. Chem., 1935,30, [ B ] , 258.36 H. L. Johnston and W. 23. Girtuque, loc. cit., ref. (7G).37 R. W. Blue and W. F. Giauque, loc. cit., ref. (77).38 J. 0. Clayton and W. F. Qiauque, Zoc. cit., ref. (92)MOELWYN-HUGHES : CHEMICAL KINETICS. 89as 10" The disagreement between thermal and spectroscopicentropies of benzene has been ascribed to the possibility of deviationfrom flatness of the ring,4o but similar differences have been observedfor molecules the configurations of which are in no doubt.41 Theseeffects are probably due to incomplete knowledge of the vibrationalmodes of complex molecules.The uncertainty in treating theproblem of free rotation of the methyl group in ethane may accountfor the calculated equilibrium constants for C,H, e C,H, + H,being one-half the experimental values.42 It must be emphasisedin conclusion that, whenever detailed analysis of rotational andvibrational levels is possible and accurate spectroscopic data areavailable, the statistical thermodynamic constants are more reliablethan those determined thermally by measurements based on thethird law. S. G.5. CHEMICAL KINETICS.From the benefactions of the quantum theory to chemistry ingeneral, the subject of reaction kinetics has received a rich share.The resulting new theory of chemical change incorporates theclassical theory as a special case, and has the additional advantageof affording a more intimate glimpse into the actual mechanism ofreaction.The distinction between the two theories may be illus-trated by reference to bimolecular metatheses. The classicaltheory accepts the energy of activation ( E ) as a characteristic,experimentally ascertainable property of the reaction, and thenproceeds to examine the frequency of collisions of critical violence.1The watchful eye of the theorist follows, as it were, the approachof reacting molecules until they come to grips, whereupon the eyeis closed, to be opened again only when the chemical change is afuit accompli and the products of reaction are flying apart. Thequantum theory, on the other hand, is not content with acceptingE as a dynamic datum, but aims a t evaluating it from the staticproperties of the reactants and resultants.The idea of collisionalviolence is maintained, but the watchful eye is kept wide openduring the crash, in which old atomic allegiances are seen t o be tornand new ones forged. The methods hitherto adopted for thea priori calculation of E and of other related terms are admittedly39 W. F. Giauque and M. F. Ashley, Physical Rev., 1933, 43, 81 ; H. Zeise,2. Elektrochern., 1933, 39, 905; A. R. Gordon, J . Chern. Physics, 1934, 2, 65;A., 1934, 355.40 V. Deitz and D. H. Andrews, Zoc. cit., ref. (73).4 1 D. M. Yost and C. Blair, Zoc. cit., ref. (95).42 H. A. Smith and W. E. Vaughan, Zoc. cit., ref. (70).1 H. Goldschmidt, Physikal.Z., 1909,10, 206 ; M. Trautz, 2. anorg. Clzern.,1916, 96, 190 GENERAL AND PHYSICAL CHEMISTRY.of an approximate character, yielding results which are only inpartial agreement with experiment. The qualified arithmeticalsuccess of the quantum-mechanical theory is, however, more thancounterbalanced by the general correctness of the physical hypo-theses which make such calculations possible. For the purpose ofthe present report, some knowledge of the new theory is essential;current theoretical research subsumes it, and much of the experi-mental work is most conveniently discussed in its light.The Picture of Chemical Change Drawn by Quantum Hechani~.-We shall illustrate the method of H. Eyring and M. Polanyi2 bysetting ourselves the problem of evaluating the energy of activationof the reaction Br + H,+ HBr + H, which M.Bodenstein hasshown to be 17,700 calories. The perturbation theory of quantummechanics yields the following simple expression for the potentialenergy of a triatomic system, in terms of the Coulombic energies,A , B, and C, and of the exchange or resonance energies, a, p, and y :In general, the magnitude of the six separate contributions to thetotal energy is not known, but the quantities ( A + a), (B + p),and (C + y ) can be directly found from the Morse functions of therelevant diatomic configurations. The evaluation of E thus requiresa knowledge of the proportion of the total energy which is contri-buted by the Coulombic terms. The absence of a fixed or universalmethod of estimation and the approximate nature of the actualestimation are the first vulnerable points in the theory.Thepreviously accepted value of 3.5% is certainly too low ; and it is nowbelieved that 14%, which is known to hold for the hydrogen molecule,is nearer the mark. Adopting it, we may rewrite equation (1) thus :E = A + B + c + (*[(a - N2 + (P - r>2 + (a - 7421)* (1)= 0*14{(A + a) + (B + PI + (C + y)> + 0.61W + 4 - (B + P)I2+[(B+P)-((C+y)I2+[(A+a)-((C+y)l2)) (2)The theoretically justifiable step of considering only linear combin-ations of the three atoms, e.g.,II I A mII I - - - I -‘+--I 1 Q-t,introduces an obvious simplification, enabling us to write’ (3) I ( A + a) = DIH,[ 1 - e-aHsCrl - ro(WI]2(B + p) = DIHBr[1 - e-aHBr[rz - ro(HBr)l]2(C + y ) 3= DIHBr[ 1 - e- a ~ ~ ~ [ r a + r1 - rdHBr)I]2Z.physsikd. Chem., 1931, [BJ, 12,279.W. Heitler and F. London, 2. Physik, 1927, 44, 455MOELWPN-HUGHES : CHEMICAL KINETICS. 91where D‘ is the energy of dissociation (D) plus the zero-pointenergy (&v0). By combining equations (2) and (3), we obtain anexpression for the potential energy of the triatomic system in termsof two spatial co-ordinates, rl and r2 (Fig. 1).The initial system consists of a free bromine atom at an infinitedistance away from a stable hydrogen molecule, and is representedby a point [r2 = co ; rl = ro(Hz) ; E = D’Ha] in the top left-handcorner of Pig. 1. The final system corresponds to a free hydrogenatom, infinitely separated from a stable hydrogen bromide mole-cule, and is characterised by the point [r, = co ; r2 = ro(HBr);FIG.1.0.5 $0 2:or, (k).E = D’HBr]. The passage of the system from its initial to its h a 1state clearly corresponds to the occurrence of the chemical reactionBr + HH --j BrH + H, for which the heat of reaction is simplyD’HH - D’HBr. The easiest of an infinite number of such passages isthat traced by the broken line. If we imagine ourselves to take theplace of the representative point of the reacting system, we can gaina clearer view of what happens. Starting at x, we climb a gentleascent southwards in a valley flanked by mountains, those on ourright being the steeper. Round about the position y, there is avirtually horizontal walk, beyond which we descend into it secondvalley eastwards.The crux of the theory of Eyring and Polanyiis the identification of the height of the pass with the energy o92 GENERAL AND PHYSICAL CHEMISTRY.activation. The critically activated complex, represented by thepoint y, has certain definite probabilities of changing and of beingformed in either of two ways : H + HBr zz [H---H---Br] zzH, + Br. From the magnified contour of the saddle region(Pig. 2), the complex is characterised by rl = rz = 1.43 A. andE = 22,100 calories. The identity of rl and r,, though possiblyaccidental, fits in with the hypothesis of D. S. Villars that E isthe minimum energy of the system which is compatible with equalatomic separations. The discrepancy between the observed andcalculated vaIues of E is due partly to the approximate nature ofLondon’s equation, to the uncertainty about the Coulombic exchangeratio, and to the omission of statistical averaging.The energy-mountain model, in spite of its crudeness, is the rock upon whichFIG. 2.quantum-mechanical theories of chemical change are built. Itis believed to depict, at least in broad outline, the essential featuresof the mechanism of those simple chemical reactions which proceedwithout electronic transitions. Such reactions are said to beadiabati~.~General Considerations on the Pot en tial- energy Mountain .-Ahelpful aspect of the present theory is the light which it throwson some of the obscure factors which determine the course ofchemical change. Expressions similar to equation (1) have beenderived for systems consisting of more than three atoms.Eyringand Polanyi’s comparison of the theoretical energies of activation4 J. Amer. Chem. SOC., 1930, 52, 1773.6 F. London, 2. Elektrochem., 1929, 35, 552; J. H. van Vleck and A.Sherman, Rev. Mod. Physics, 1935, 7, 167; H. Hellmann, Acta Physico-chimica U.R.S.S., 1936, 1, 913.F. London, Sommerfeld Festschrift, p. 104, Hirzel, Leipzig, 1928MOELWYN-HUGHES : CHEMICAL KINETICS. 93of the two reactions H, + o-H, -+ H, + p-H, and H + o-H, _j.H + p-H, showed E to be smaller for the latter reaction, whichshould therefore, ceteris paribus, be the more likely to occur. Theconclusion is in agreement with the actual mechanism establishedby A. Farkas.7 A comparison of the calculated E's for the reactionsC2H41, --+ C2H4 + I, and C,H41, -+ I + C2H4 + I, + I revealedbut a trifling difference; hence the two reactions should occurconcurrently, as is found to be the case.9 The predominant, thoughnot exclusive,lo addition of bromine in the 1 : 4-positions of thebutadiene molecule has received a similar explanation.11 As themechanism of each reaction had been established by experimentbefore theoretical computations were made, it is evident that thefunction of the theory in this direction has, up to the present, beenone of interpretation rather than of prediction.Perhaps thesuitable note to strike at this juncture is not lament at the inabilityto predict, but delight at the ability to interpret.The velocity of chemical reaction is determined by the number ofmolecules which possess the necessary energy ( E ) and by the prob-ability (G) per unit time that the activated molecules will suffertransformation.E is represented by the height of the col, and Q bythe probability that the representative point surmounts it. Ourestimate of G depends on whether the process obeys the laws ofclassical or those of quantum mechanics. Consider a one-dimen-sional barrier with a height corrt:sponding to E. According toclassical mechanics, the chance that a freely moving particle willsurmount it is independent of its shape; particles with energy Wwill always pass the top provided W 2 E , and will never pass itwhen W <E. According to quantum mechanics, the probabilityof transit is finite even when W < E, and amounts to certaintyonly as W --+ CO. In principle, C can always be evaluated whenthe potential energy barrier has been expressed analytically.l2 Bymaking assumptions about the shape of the barrier, expressions canbe deduced l3 relating its permeability (G) with its height ( E ) andwidth. Numerical computations for barriers of plausible widths7 2. physikal. Chem., 1930, [B], 18, 419.8 A. Sherman and C. E. Sun, J . Amel.. Clzem. SOC., 1934, 56, 1096.9 L. B. Arnold and G. B. Kistiakowsky, J . Chem. Physics, 1933, 1, 166.10 G. B. Heisig and J. L. Wilson, J . Arner. Chem. SOC., 1935, 57, 859.11 H. Eyring, A. Sherman, and G. E. Kimball, J . Chem. Physics, 1933, 1,12 E. Wigner, 2. physikal.Chem., 1933, [B], 19, 203.13 D. G. Bourgin, Proc. Nut. Acad. Sci., 1929,15,357 ; R. M. Langer, PhysicalRev., 1.929, 33, 290; C. Eckart, ibid., 1930, 35, 1303; S. Roginsky and L.Rosenkewitch, 2. physikal. Chem., 1930, [B], 10, 47; E. Wigner, PhysicalRev., 1932, 40, 749; C. Zener, Proc. Roy. SOC., 1932, [A], 137, 696.58694 GENERAL AND PHYSIUAL CHEMISTRY.and heights 14 show that G approximates to the classical valueexcept when the mass, temperature, and energy of activation arelow. It is conceivable that certain reactions exist, the rate ofwhich is governed by the quantum-mechanical transmission ofa hydrogen atom or proton, rather than by the co-ordinatedevolutions of a system of atoms. Bell1* has shown that, adoptinga barrier of the shape postulated by Eckart l3 for an athermicreaction with E = 14,500 calories and a width of 2 8., G varieswith T in such a way that the Arrhenius E would be only 6,300calories.If the somewhat speculative computations approximateto the truth, large differences are to be expected between observedand theoretical values of E. However, the behaviour of reactionsinvolving massive particles may confidently be regarded as classical(G = 1 when W 2 E), particularly when E is appreciable.Recent classical treatments of the passage of the representativepoint over the col15 have been synthesised and elaborated into atheory of great attractiveness by H. Eyring,lG who considers thecritical complex to resemble a stable molecule in all respects exceptin the motion along the co-ordinate of decomposition. On accountof the flatness of the saddle region, the motion in this degree offreedom is regarded as classical.The governing idea is that thepassage over the col is associated with constancy in the number,but change in the nature, of the degrees of freedom. When, forexample, two atoms A and B collide to form a complex A .. . B,from which the stable molecule AB will ultimately emerge, thesix translational degrees of freedom (three for each atom) areconverted into three degrees of translation of the complex A . . . Bas a whole, two degrees of freedom of rotation, and-most importantof all-one degree of freedom of translation of the atoms A and Bwithin the complex, along the line of centres. The velocity ofreaction is largely a function of the energy in this special degree offreedom.Quantitative developments have recourse to a generaltheorem in statistical mechanics 1’ (see also p. 66) which relates theequilibrium constant ( K ) , for unit volume, with the energy change(E,) and the relevant partition functions ( F ) :K = F ~ B . e-Eo’RT/FaFB . . . . * (4)l4 R. B. Bell, Proc. Roy. SOC., 1933, [ A ] , 139,466 ; 1935, 148, 241 ; C. E. H.Barn and G. Odgen, Trans. Paraday Xoc., 1934, 30, 432.l5 E. Wigner and M. Polanyi, 2. physikal. Chem., 1928, 139, 439; H.Pelzer and E. Wigner, ibid., 1932, [B], 15, 445 ; 0. K. Rice and H. Gershino-witz, J. Chem. Physics, 1934, 2, 853; W. H. Rodebush, ibid., 1933, 1, 440;1935, 3, 242; M. G. Evans and M.Polanyi, Trans. Paraday Xoc., 1935, 31,875.l6 J . Chem. Physics, 1935, 3, 107.l7 R. H. Fowler, “ Statistical Mechanics,” Chap. V, Cambridge, 1929MOELWYN-HUGHES : CHEMICAL KINE’MCS. 95The evaluation of F is in general a difficult matter, unless the motionsare completely classical or completely quantised, and can be treatedas virtually independent. In such cases, F factorises into F1F2F3. . .Extracting from FAB the factor which takes account of the motionin the ‘‘ co-ordinate of decomposition,” and regarding this motion asone in a force-free field, we get :K = (FZ*/FAFB). e-EO/RT. dZnmkT/hThis expression gives the concentration of critical complexes a t thecol ; multiplication by the average velocity dLT/2nm of transit overthe col gives us Eyring’s general formula for the velocity of reaction :In the particular example discussed here, F,&/FA.FB becomeshZ/lcT, where Z is the kinetic-theory value for the frequency ofbinary collisions. The classical equation for the velocity of simplebimolecular processes is thus deducible from somewhat novelpremises. The theory has been helpful in elucidating severalproblems, including the rates of homologous unimolecular reactionsin gases,l* the negative temperature coefficient of the velocity oftermolecular reactions,lg and the variation of the steric factor withmolecular complexity.20 Its application to the problems of reactionsin solution21 makes appeal to the idea of entropy of activation.22Attention has been directed 23 to errors in the treatment of Wynne-Jones and Eyring.An extension of the energy-mountain technique has shown theway to the calculation of the energy of activation of simple ionicreactions.24 We shall illustrate the method by discussing thereaction CH,C1 + I’ -+ CH31 + C1’ in acetone solution.Thecharge on the attacking ion and the sign of the dipole predisposethe approach to take place in the manner indicated :k = (F&/FAFB) . e-EotRT . ET/h . . . (5)During chemical change, therefore, the methyl chloride molecule isturned inside out, like an umbrella in a strong wind. This mechan-l8 0. K. Rice and H. Gershinowitz, J . Chem. Physics, 1935, 3, 479.l9 H. Gershinowitz and H. Eyring, J . Amer. Chem. SOC., 1935, 57, 985.2O C. E. H. Brzwn, Trans. Paraday SOC., 1935, 31, 1536.21 W.F. K. Wynne-Jones and H. Eyring, J . Chem. Physics, 1935, 3, 492.22 F. G. Soper, Discussion on the Critical Increment, Chemical Society,23 E. A. Moelwyn-Hughes, ibid., in the press.24 R. A. Ogg and M. Polanyi, Trans. Paraday SOC., 1935,31, 604.1931, p. 45; V. K. LaMer, J . Chem. Physics, 1933,1, 28996 GENERAL AND PHYSICAL CHEMISTRY.ism was dictated by the facts of the Walden inversion, and isconsistent with Lowry's theorem that reaction takes place throughthe intermediate formation of a compound of higher symmetry.Direct support for it has recently been given by E. D. Hughes,F. Juliusberger, S. Masterman, B. Topley, and J. we is^,^^ who haveestablished experimentally the identity in the rate of inversion ofsec.-octyl iodide and the rate with which the iodine atom is exchangedby its radioactive isotope.Ogg and Polanyi's expression for thepotential energy of the reacting system may be writtenwhere rl is the separation of the iodine ion, and r2 that of the chlorineatom, from the carbon atom, the polarisability of which is CI.DCH3CI is the heat of dissociation, and a and ro are the Morse constantsfor methyl chloride. The heat of solvation (XI-) of the iodine ionis computed from the constants (b, and p ) of the repulsive field incrystals.26 The use of a similar expression for the potential energy(E,) of the product system allows an evaluation of the energy ofactivation ( E ) . Among the factorswhich are omitted from the treatment, one may mention theinfluence of the cation, the inclusion of which leads to a bettervalue of E.Several conclusions of a qualitative, or a t best asemi-quantitative, nature may be drawn from general considerationsof the solid geometry of potential-energy models. Some of theproblems relating to chemil~minescence,~~ prototropy 28 andexchange 29 have been approached from this angle. By a combin-ation of the methods of Eyring and Polanyi for non-polar systemswith those of Ogg and Polanyi 24 for ionic systems, potential surfaceshave been constructed for simple chemical changes where thereactants are of one kind and the resultants of an~ther.~OSince the velocity coefficient (Ic) is usually proportional toe-E'RT, any influence which lowers the energy of activation increasesthe velocity, and is thus positively catalytic.The introductionof an ion, a dipole, or a, polarisable atom or molecule into anelectrically neutral reacting system may, of course, increase ordecrease the potential energy; and the height of the col maythereby be raised or lowered. I n the former case, however, thedisturbance merely makes possible an alternative mechanism whichThe result is 50% too high.2 5 J., 1935, 1525.2 6 M. Born and J. E. Mayer, 2. Physilc, 1932, 75, 1.2 7 R. A. Ogg and M. Polanyi, Trans. Paraday SOC., 1935, 31, 1375.2 8 J. Horiuti and M. Polanyi, Acta Physicochirnica U.R.S.S., 1935, 2, 505.2o R. A. Smith, Proc. Camb. Phil. SOC., 1934,30, 508.30 A. G. Evans and M. G. Evans, Trans. Paraday Xoc., 1935,31,1400MOELWYN-HUGHES : CEEMICAL KINETICS.97is less likely to occur than the undisturbed process, and may there-fore be ignored. In the latter case, the disturbed mechanism isthe more facile, and may replace the original one. Steps towardsthe formulation of a quantum-mechanical theory of catalysis havealready been taken.31It is a matter of interest to inquire into the possible connexionbetween the processes of activation, as the term is understood inchemical kinetics, and of the excitation of vibrational quanta. Thestudy of the latter phenomenon is advancing rapidly.32 Quantitativeapplications of the theories presuppose a precise knowledge ofinteratomic force-fields, and are possible only in very simple cases.Approximate solutions to the problem being a~cepted,3~ it canreadily be shown, for example, that the chance of a hydrogen atomexciting the first vibrational quantum in the molecule of hydrogenbromide is negligible compared with the chance of chemical reaction,in all relevant collisions.On the other hand, with molecules ofslightly higher complexity, the interchange of translatory andvibrational energy is of some importance. C. N. Hinshel~ood,~~co-ordinating the salient facts relating to the catalytic decompositionof gaseous aldehydes, ethers, and nitrous oxide, points out that theefficient catalysts (e.g., iodine, halogen atoms, nitric oxide, andoxygen) possess the qualities (polarisability, free valency, oddelectron, and magnetic moment) which according to classicaltheory favour specific energy transfers.The distinction thusappears t o be due to the fact that, with an organic molecule,vibrational excitation occurs in bonds other than that which iseventually broken. Hinshelwood differentiates between a pre-activated molecule and a critically activated one : both possess thenecessary energy, but the former laeks the appropriate internaldistribution, while the latter possesses the necessary energy in theright spot, and will decompose in the course of the next completevibration. Further reference will be made to the question of theinternal redistribution of energy (see p. 108).Atomic Reactions.-The study of reactions involving the simplereplacement of one atom by another offers obvious advantages.31 H. M.James and A. S. Coolidge, J . C7~em. Phyaics, 1934, 2, 811; A. E.Stearn, J. Gen. Physiol., 1934, 18, 171 ; A. A. Schuchowitzky, Acta Physico-chimica U.R.S.S., 1935, 1, 901; R. M. Langer, loc. cit., ref. (13).33 0. Schmidt, Ann. Physlsik, 1934, 21, 241; H. 0. Kneser, Physikal. Z.,1934, 35, 983; A. Eucken and R. Becker, 2. physilcal. Chem., 1934, [B], 27,219; J. E. Lennard-Jones and C. Strachan, Proc. Roy. SOC., 1935, [ A ] , 150,442.33 N. F. Mott and H. S. W. Massey, “ The Theory of Atomic Collisions,”p. 248, Oxford, 1933.34 J., 1935, 1111.REP.-VOL. XXXII. 98 GENERAL AND PHYSICAL CHEMISTRY.A profitable approach t o the investigation of any given chemicalreaction, say A + BC --+ AB + C, is to examine it in conjunctionwith the sister reaction A + BD + AB + D, where C and Dbelong to the same family in the periodic table, Experience shows,however, that the study of the second reaction, instead of solving ourfirst difficulties, very often introduces new ones.We find ourselvest o be, in fact, very near the core of chemistry, which holds thesecret of the specificity of the various forms of matter. Aninvestigation of the twin reactions A + BD, + AB + D, andA + BD, --+ AB + D,, where D, and D, are isotopes of the sameelement, should take us a stage nearer the goal, because isotopicspecificity, for all chemical purposes, is confined to those propertieswhich are directly related t o their masses. Of these properties,zero-point energy is one of the most important.35 From accuratespectroscopic values of V, we have, for hydrogen, EoHI = 6,180, andfor deuterium, EoDz = 4,390 calories per g.-mol., hence EoEt - E*D, =1,800. The simplest known chemical reactions are (1) H + H, --+(4) D + H, 4 DH $- H.Kinetic information about them iswell-nigh complete.36 The first two are the ortho-para conversionof hydrogen and deuterium; the second two are the significantsteps in the reaction H, + D, 2HD. The difference in velocityof reactions (1) and (2) is due to two factors, vix., the difference inthe collision frequencies and that in activation energies, whichexperiment shows to be about 500 calories. Now the energy ofactivation ( E ) is defined as the difference between the energy (E*)of the activated state (HHH or DDD) and the energy (E") of theinitial state (H2 or D2); hence E&E - E z D D = (EOH, - EOD,) -/-(EE,,H - ED2,D) = 1,300.This quantity is in agreement with thedifference calculated for the energies of the systems HHH and DDDby making plausible assumptions about the force constants. Muchof the existing literature has been considered in this light. Theadditional data for HHD, HDD, HDH, DHD, HNBr, DDBr,HHC1, etc., make it appear probable that critical complexes do, infact, possess zero-point energy, and thus resemble stable moleculesat least in one respect. The difference in E for the reactions Na +H C l 4 NaCl + H (6,100 cals.) and Na + DCl-> NaCl + D(6,400 cals.) has been independently accounted for in the same way.37G. Schay has continued his work on the interaction of alkali atomsH,+H; (2) D+D,+D,+D; (3) H+D,---t.HD+D;3 5 (Frl.) E.Cremer and M. Polanyi, 2. physikal. Ci~em., 1932, [B], 19, 443.36 A. Farkas and L. Farkas, Proc. Roy. Soc., 1935, [A], 152,124; A. Farkas,(' Ortho-Hydrogen, Para-Hydrogen, and Heavy Hydrogen," Cambridge,1935.3 7 C. E. H. Bawn and A. G. Evans, Trans. E'araday Suc., 1935, 31, 1392MOELWYN-HUGHES CHEMICAL KINETICS. 99with molecules of halogen38 and of mercury halides.39 Except fora few details, the mechanism of reaction with potassium atoms isthe same as that established with sodium.40 The homogeneousreaction K + I,---+ KI + I + q1 cals. is followed by a wallreaction K + I + KI and by a second homogeneous reactionK, + I+ KI + K + 4, cals. The state of electronic excitationof the emergent potassium atom is governed largely by the magnitudeof the heat effect 4,.The violet doublet is absent from the flamespectrum, in agreement with thermodynamic anticipation. Fromthe temperature variation of one of the contributions to the totallight intensity, the heat of dissociation of the reaction K, zz 2K isfound t o be 18,700 cals. The rate and energy of activation for thereaction between sodium atoms and monohalogen derivatives ofbenzene have been measured and discussed,41 as well as thereactions 42343 0 + NO, -+ NO + 0, and Br + C1, + BrCl + C1.The actual union of two atoms to form a covalent molecule differsfrom the pictorial account discussed on p. 91, in that it requires thepresence of a third atom or molecule to render the collision effective.The third partner may be a part of the wall of the reaction vessel,or a free atom or molecule in the gas.W. Steiner, whose earlierwork44 on the mechanism of ternary encounters has received newconflrmati0n~4~ has elaborated his theory of the recombination ofhydrogen atoms.46 After allowing for the diffusion of hydrogenatoms to the wall, it appears that the reactions H + H + Molecule-+ H, + Molecule and H + H + Atom- H, + Atom havevelocities in the approximate ratio of 9 : 10. Hydrogen atoms havebeen found to combine 1.36 times as fast as deuterium atoms, inagreement with our knowledge of the identity in diameters andforce constant^.*^ G. M. Schwab 48 has shown that every collisionbetween a bromine atom from the gas phase and a similar atomadsorbed on the wall is effective.38 E.Roth and G. Schay, 2. physikal. Chem., 1935, [B], 28, 323.3g I. Bereger and G. Schay, ibid., p. 332.40 M. Krocsak and G. Schay, ibid., 1032, [B], 19, 344. References to stillearlier work have been given by E. K. Rideal, Ann. Reports, 1928, and byC. N. Hinshelwood, ibid., 1930, 1931.4 1 F. Fairbrother and E. Warhurst, Trans. Paraday SOC., 1935, 31, 987.42 M. L. Spielman and W. H. Rodebush, J . Amer. Chem. SOC., 1935,57,1474.43 G. Brauer and E. Victor, 2. Elektrochem., 1935, 41, 508.44 2. physikal. Chem., 1931, [B], 15, 249.45 L. Farkas and H. Sachsse, ibid., 1934, [B], 27,111 ; G. A. Cook and J. R.Bates, J . Amer. Chem. SOC., 1935, 57, 1775.46 W. Steiner, Trans.Faraday SOC., 1935, 31, 623, 962.47 I. Amdur, J . Amer. Chem. SOC., 1935, 5'9, 856.48 2. phyeikal. Chem., 1934, [B], 27, 452.IT. L. Lehmann, Trans. Paraday SOC., 1035, 31, 689.See also E. Rabinowitch an100 GENERAL AND PHYSICAL CHEMISTRY.As a matter of pure nomenclature, it may be pointed out that theterm “ exchange reaction ” is being accepted for changes involvingthe replacement of an atom by one of its isotopes. The mechanism,as we have seen, is usually an atomic one.More Complicated Reactions in the Gaseous Phase.-The repetition-perhaps inevitable-of some of the key experiments has con-solidated the territories gained during the last decade in this domain.A reinvestigation 49 of the reaction CH,*CHO -+ CH, + COunder the original conditions yields no evidence that it is appreciablyheterogeneous, as is the case a t lower temperatures50 or that itdepends upon a chain mechanism.It also appears 51 that thestationary concentration of hydrogen atoms is too low t o maintainthe type of chain mechanism mooted by F. 0. Rice and K. F.H e r ~ f e l d . ~ ~ The catalytic influence of oxygen and of two oxidesof nitrogen on this reaction has been st~died.5~ The decompositionof nitrous oxide, examined under pressures amounting to 40 atmo-s p h e r e ~ , ~ ~ confirms the conclusions of F. 3’. Musgrave and C. N.Hin~helwood.5~ For both these reactions, the apparent E increasesas the pressure is raised. The r81e of keten as the intermediatecompound in the unimolecular decomposition of acetone has beenquantitatively studied ; again, there is evidence for compositeactivation and for the absence of long chains.56 The thermaldecomposition of ozone has been the subject of repeated investig-ation 57 and discussion.58 Azomethane explodes a t temperaturesslightly higher than those a t which H. C. Ramsperger measured thequiet unimolecular decomposition.59 The study of the formation ofhydrogen sulphide from its elements continues to offer difficulties,but the r81e played by sulphur atoms is becoming clearer.60 Thereaction between hydrogen and oxygen attracts unabated attention.The influence thereon of replacing hydrogen by deuterium,61 of49 C. A. Winkler and C. N. Hinshelwood, Proc. Roy. SOC., 1935, [A], 149,50 M. W. Travers, Proc.Roy. Xoc., 1934, [ A ] , 146,284; Nature, 1935,135, Till.81 F. Patat and H. Sachsse, Naturwiss., 1935, 23, 247.62 J . Amer. Chem. SOC., 1934, 56, 284.s3 F. H. Varhoek, Trans. Paraday Xoc., 1935, 31, 1521; E. W. R. Steacie54 E. Hunter, Proc. Roy. SOC., 1934, [ A ] , 144,386. 55 Ibid., 1932,135,23.5 6 C. A. Winkler and C. N. Hinshelwood, ibid., 1935, [A], 149, 340.5 7 M. Ritchie, ibid., 1934, [A], 146, 848.58 H. J. Schumacher, ibid., 1935, [ A ] , 150, 220; M. Ritchie, Nature, 1935,355; M. Letort, Cornpt. rend., 1935, 200, 312.and R. D. Macdonald, Canadian J . Res., 1935, 12, 711.136, 221.A. 0. Allen and 0. K. Rice, J . Amer. (772,em. SOC., 1935, 57, 310.60 E. E. Aynsley, T. G. Pearson, and P. L. Robinson, J., 1935, 58.61 C. N. Hinshelwood, A, T, Williamson, and J, H.Wolfenden, PTOC. Rqy.SOC., 1934, [A]$ 147, 48MOELWYN-HUGHES : CHEMICAL KINETICS. 101salt-coating the walls,62 of passing electric dis~harges,~~ of intro-ducing tetraeth~l-lead,~~ and of the presence of a palladium catalyst 66have all been examined. Recent values of the lower explosionlimit 66 are somewhat lower than those found originally. The lowerexplosion limit for the oxidation of phosphine has been re-examinedunder a wide variety of conditions by S. C. Gray and H. W. Mel-~ i l l e , ~ ~ whose results, along with recalculated values for eight otherreactions, confirm the accepted t,heory. New data on the lowerexplosion limit for the oxidation of carbonyl sulphide and of silanehave been published by H.Gutschmidt and K. Clusius.67aThe number of recorded chemical phenomena which find theirreadiest interpretation in terms of the chain theory is rapidlyincreasing.67b For example, R. G. W. Norrish 68 has shown that theoxidation of hydrocarbons-now definitely established as a directattack by oxygen 69-which yields such complicated analyticaland kinetic results, can be represented in terms of quite a simplechain mechanism. A helpful summarising article on this subjecthas also been given by W. Jost.’O Polymerisation reactions offerspecial opportunities for displaying the power of the chain theory.71These interesting chemical changes are gaining a new importance ;but the time does not seem ripe for discussing them in these Reports.We shall, however, refer to them again in a later section.The chaintheory itself has been elaborated in two directions. To accountfor the widening out of the explosion limits consequent upon theintroduction of artificially generated chain centres, N. Semenoff 72has postulated a mutual interference of the chains. I n order toexplain the rapidity with which explosion waves travel in deton-ations, K. I<. Andrkew and J. B. Chariton 73 invoke the idea ofmacro-chains, New experiments to which the less elaboratetheory has been applied include those on the explosion of ethyl62 M. Prettre, C’ompt. rend., 1935, 200, 132.a3 G. Gorchakov and L. Lavrov, Actii Physicochimica U.R.S.S., 1934,1,139.64 H. G . Tanner, J . Amer. Ghem. Soc., 1934, 56, 2250.6 5 D. L.Chapman and G. Gregory, Proc. Roy. SOC., 1934, [ A ] , 14’9, 68.6 6 W. E. Garner and H. J. Willavoys, Trans. Paraday SOC., 1935, 31, 806.6 i b N. Semenoff, “Chemical Kinetics and Chain Reactions,” Oxford, 1935.6 8 Proc. Roy. SOC., 1935, [ A ] , 150, 36.09 W. A. Bone and J . Bell, ibid., 1934, [A], 144, 257.70 2. Elektrochem., 1935, 41, 186.7 1 H. Dostal and H. Mark, 2. physsilcal. Chem., 1935, [B], 29, 299; G. Geeand E . K. Rideal, Trans. Paraday SOC., 1935, 31, 969. A Report of theFaraday Society’s Discussion on Polymerisation is to be published in 1936.A preliminary survey (E. K. Rideal, Nature, 1935, 135, 626) has alreadyappeared.Ibid., p . 452. 67a Z. phyaikal. Chem., 1935, [B], 30, 265.72 2. physikal. Chem., 1935, [B], 28, 31.73 Trans. Paraday SOC., 1935, 31, 797102 GENERAL AND PHYSICAL CHEMISTRY.nzide, 74 the oxidation of pr~paldehyde,~~ the chlorination of pro-pane,76 the polymerisation of f~rmaldehyde,~~ the reaction betweencarbon monoxide and nitrous oxide,78 and the effect of hydrogenon the carbon monoxide flame.79Brief mention must be made of the increasing variety of decom-position reactions which have been recently studied.The followingcompounds decompose by a unimolecular mechanism in the homo-geneous gas phase : methyl 8* and sec.-butyl 81 iodides; nitro-methane ; methyl,83 mpropyl,84 and isopropyl s5 nitrites ; andb dyoxa1.86 Only the primary step in the decomposition of methyl-amine 87 is homogeneous; increased surface inhibits the rate ofdecomposition of propylamine,88 an effect which is apparentlyabsent in the case of trieth~lamine.~~ An interesting exampleof intermolecular conversion obeying the unimolecular law is the iso-merism of cis-methyl inna am ate.^^ Bimolecular behaviour is ex-hibited by the polymerisation and hydrogenation of a ~ e t y l e n e , ~ ~by the decomposition of nitrosyl and predominantly bythe decomposition of a~raldehyde.~~ The effect of iodine on therate of decomposition of chloral 9* is consistent with a bimolecularmechanism involving iodine atoms ; catalysis by nitric oxide issimilarly inter~reted.~5 The decomposition of nickel carbonyl 96follows a more complicated course.74 H.C. Campbell and 0. K. Rice, J . Amer. Chem. SOC., 1935,5'7,1044.7 5 E. W. R. Steacie, W.H. Hatcher, and S. Rosenberg, J . Physical Ckem.,7 6 S. Yuster and L. H. Reyerson, ibid., 1935, 39, 859.7 7 J. E. Carro%hers and R. G. W. Norrish, Nature, 1935, 135, 582.7 8 C. E. H. Bawn, Trans. Faraday SOC., 1935, 31, 461.79 W. E. Garner and F. H. Pollard, J., 1935, 144.80 E. W. R. Steacie and R. D. Macdonald, J . Arner. ClLem. SOC., 1935,57,488.81 R. A. Ogg and M. Polanyi, Trans. Faraday SOC., 1935, 31, 482.82 H. A. Taylor and V. V. Vesselovsky, J. Physical Chem., 1935, 39, 1095.83 14:. W. R. Steacie and G. T. Shaw, Proc. Roy. SOC., 1934, [A], 146, 388.8 4 Idem, J . Chern. Physics, 1935, 3, 345.6 5 Idem, Proc. Roy. SOC., 1935, [A], 151, 685.86 E. W. R. Steacie, W. H. Hatcher, and J. F. Harwood, J . Chem. Physiqv,87 H. J. Emel6us and L.J. Jolley, J., 1935, 929.88 D. V. Sickman and 0. K. Rice, J . Arner. Chem. SOC., 1935, 5'7, 22.s9 H. A. Taylor and E. E. Juterbock, J . Physical Chem., 1935, 39, 1103.90 G. B. Kistiakowsky and W. R. Smith, J . Amer. Chem. SOC., 1935,57,269.91 H. A. Taylor and A. van Hook, J . Physical Chem., 1935, 39, 811.92 G. Waddington and R. C. Tolman, J . Amer. Chem. SOC., 1935, 57, 698.93 H. W. Thompson and J. J. Frewing, J., 1935, 1443.g* F. H. Verhoek and C. N. Hinshelwood, PTOC. Roy. SOC., 1934, [A], 146,334.9 5 F. H. Verhoek, Trans. Paraday SOC., 1935, 31, 1521.96 A. P. Garratt and H. W. Thompson, J., 1934, 1822; C. E. H. Bawn,1934, 38, 1189.1935, 3, 291.Trans. Paraday SOC., 1935, 31, 461MOELWYN-HUGHES : CHEMICAL KINETICS. 103Reactions in Solution.-Advances in this field have dependedmore on the correct interpretation of existing data than on thediscovery of new reactions.Our virtual ignorance of the natureof interaction in the condensed phase, long used as an excusefor shunning the problem, is now recognised as a, reason forstudying it.Many of the reactions which proved helpful in instituting it co-ordinated theory of reactions in solution have been reinvestigated ,with confirmatory results. To the sole instance previously known,two others have been added (C,H,12 + I+ C,H4 + I, + I and0, + p-H, + 0, + o-H,) of bimolecular reactions which have beenmeasured in the gas phase and in solution : 97, 98 they have the sameE and li: in the two phases. These results afford the most directknowledge we have of the frequency of binary collisions in dilutesolution.They support the anticipations of Christiansen (1923)’Tolman (1927), and others that 2 is of the same order of magnitudein the two systems. A third example (COX + H,O --+ CO, +H,S) gives E = 25,700 for the predominantly homogeneous gasreaction, and E = 22,700 for the condensed reaction; collisionsin the latter case, however, are hetween solute and solvent mole-cules ; if their frequency is calculated by the equation ,Z, = 3xr)o/2m,E for the condensed reaction becomes 26,300 ~als.9~ Furtheranalogies between collision frequencies in the two systems may bedrawn from the work on quenching of fluorescence in gases andliquids.1 A. W. Chapman, has shown that the velocity of theBeckmann transformation of benzophenoneoxime picryl ether,catalysed by a variety of substances in carbon tetrachloride, has thesame value as that computed for the hypothetical gas reaction,the observed E’s and the gas kinetic collision formula being used.The assumption that reactions of the type R,ONa + R,Cl+R,0R2 + NaCl are chiefly ionic, involving R,O’ ions, has beenjustified by more reliable determinations of the degree of dis-sociation.3 The similarity of the k’s for homologous reactions hasbeen discussed in terms of the theory of coupled oscillators.4 Thedistinction drawn between these etherifications and reactions ofthe type R,R,R,N + R,Cl-+ R,R,R,R4NC1 has been heightenedby the response of the two to high pressures, which has been accur-9 7 LOC.cit., ref. (9), p. 93.9s L. Farkas and H. Sachsse, 2. physikal. Chem., 1933, [B], 23, 1.99 H. W. Thompson, C. F. Kearton, and S. A. Lamb, J., 1935, 1033.1 ,J. Franck and H. Levi, 2. physikal. Chem., 1934, [B], 27, 409.2 J . , 1934,1550 ; 1935,1223 ; see also K. D. Anderson and D. L1. Hammick,3 p. J. Hardwick, ibid., 1935, 141.4 H. Pelzer, 8. EZektrochem., 1934, 39, 608.ibid., p. 30104 GENERAL AND PHYSICAL CHEMISTRY.ately studied.5 The rate of formation of urea and of monomethyl-urea to form cyanate ions and the corresponding cations has beenthe subject of precise and extensive work in various media,6enabling the relation between critical increment and ionic strengthto be verified and elaborated.' The expected independence of Eof electrolyte concentration has been demonstrated for numerousreactions of zero ionic type, including the acid hydrolysis of diethyl-aceta18 and ethyl a ~ e t a t e , ~ and the basic hydrolysis of the acetyl-glycollate ion, for which over 300 values of E have been published.10The value of E recently found for the mutarotation of glucose inwater (18,000) l1 is in better agreement with the classical value of17,700 given by Hudson and Dale in 1917 than with the amendedvalue of 19,300 published by Kilpatriclr in 1931.The rates ofreactions of the type R1R2S + R,Cl _t R1R2R,SC1 have hithertobeen inferred quantities ; direct measurements have now been madein various solvents.12 Distinctly less attention is being paid to thestudy of reactions of the first and the third order.New instances ofthe unimolecular cleavage of carbon dioxide from acids have,however, been examined,13 and the alleged termolecular reactionbetween stannous and ferric chlorides has been shown to be fairlycomplicated.14 The latter change bears many of the distinguishingfeatures of a chain reaction, though it has not yet been discussed fromthis angle. The search is also being continued for a satisfactoryexplanation of the kinetics of those complicated reactions involvinghalide, hypohalite, halite, and halate ions in aqueous s01ution.l~E. W. Fawcett and R. 0. Gibson, J . , 1934, 386; R. 0. Gibson, E. W.(Miss) C. C. Miller, ibid., 1934, [ A ] , 145, 288; 1935, [ A ] , 151, 188.J . C. Warner and collaborators; with F.€3. Stitt, J. Amer. Chenb. SOC.,1933,55,4807; with E . L. Warrick, ibid., 1935,57, 1491 ; with W. J. Svirbely,ibid., p. 1883.L. C. Riesch and M. Kilpatrick, J . Physical Chem., 1935, 39, 561.W. Wylzafkowska, Rocz. Chcm., 1934, 14, 1118.Fawcett, and M. W. Perrin, Proc. Roy. Soc., 1935, [A], 150, 223.lo A. von Kiss and R. Kukai, 2. anorg. Chem., 1935, 223, 149; Rec. trav.l1 E . A. Moelwyn-Hughes, 33. Klar, and K. F . Bonhoeffer, 2. physiknl.l2 J. K . Syrkin and I. T. Gladischew, Acta Physicochiinica U.R.S.S.,l3 (Miss) J. MUUS, J . PhysicaZ Chem., 1935, 39, 343 ; K. Beniya, J . Biochem.14 R. A. Robinson and N. H. Law, Trans. Paraday ~ o c . , 1935, 31, 899.l5 H. A. Liebhafsky, J . Amer. Chem. SOC., 1934, 56, 2369; R. M. Chapin,ibid., p.2212; W. C. Bray and H. A. Liebhafsky, ibid., p. 51; R. 0. Griffithand A. RlcKeown, Trans. Faraday SOC., 1935, 31, 868; A. Skrabal and H.Schreiner, Monatsh., 1935, 65, 213; C. F. Prutton and S. H. Maron, J . Amel..Ghem. SOC., 1935, 57, 1652.chim., 1935, 54, 337.Chem., 1934, 169, 113.1935, 2, 291.J a p n , 1934, 20, 451MOELWYN-HUGHES : CHEMICAL KINETICS. 105Four of the directions in which the subject is advancing may beindicated roughly by the terms rapid reactions, radical reactions,exchange reactions, and film reactions.The application of Hartridge and Roughton's technique 16 offersa. means of extending the range of observable phenomena in solution.In the hands of H. von Halban and H. Eisner,17 preliminary con-clusions are already derived concerning numerous organic andinorganic reactions which are half completed in about 0.001 second,and further useful information may confidently be expected fromthis source.The methods of measuring the speed of reactions insolution have formed the subject of a recent biochemical discussion.18The part played by free radicals in solution becomes moreprominent. E. Abel and K. HilferdingI9 accept the mechanismproposed by Griffith and McKeown (1932) for the action of aqueousiodine on oxalic acid. One of the three rate-determining steps isI + C,O," + C204' + I f , with E = 19,000, and a chain lengthof a few million cycles. The function of HO, in the decompositionof aqueous hydrogen peroxide has been quantitatively studied.20J.R. Velasco 21 finds that the relative rates of reaction of ketoneswith diphenylsemicarbazide are exponentially related to theiroxidation potentials ; and a complementary relation apparentlyholds for the inhibitive action of foreign substances on the reductionof mercuric chloride by picric acid.22 The energetics of some of thesteps in radical chains thus become amenable to measurement.Experiments on the replacement of the hydrated proton by thehydrated deuteron showed that the ratio a = k~~o-/k=,O- is lessthan 1 for the mutarotation of glucose, and that daldT is positive ; 23for the inversion of cane sugar, a exceeds 1, and dct/dT is negative.24The hydrolysis of methyl acetate25 runs parallel to the case ofsucrose. By applying the theory of multiple catalysis, the valueof EHoD has since been estimated a t 25°.26 E for the pseudo-uni-16 See R.Brinkman, R. Magaria, and F. J. W. Roughton, Phil. Trans,,1933, [A], 232,65.1 7 Helv. Chim. Acta, 1935,18, 724.18 A. V. Hill, H. Freundlich, 13. Hartridge, G . Millikan, F. J. W. Roughton,E. K. Rideal, J. B. S. Haldane, 31. Polanyi, and McK. Cattell, Proc. Roy. SOC.,1934, [B], 116, 185.1s 2. physikal. Chem., 1935, 172, 353.20 G. Kornfeld, ibid., 1935, [B], 29, 205; J. Weiss, Trans. Paraday SOC.,1935, 31, 668; Naturwiss., 1935, 23, 64.21 Afial. Pis. Quim., 1935, 32, 345; cf. B. F. Chow, J . Arner. C'hem. SOC.,1935, 57, 1437.22 K. Weber, 2. physikal. Chem., 1935,172,459.23 E. A. Moelwyn-Hughes, ibid., 1934, [B], 26, 272.24 E. A.Moelwyn-Hughes and K. F. Bonhoeffer, Natumuiss., 1934, 22, 174.25 J. C. Hornel, Nature, 1935, 135, 909.26 W. IT. Hammill and V. K. LaMer, J . Chem. Physlsics, 1934, 2, 891.D 106 GENERAL AND PHYSICAL CHEMISTRY.molecular reaction CH3*CO*CH, + HOD ---+ CH3*CO*CH2D + HOHis 18,000 cals. ; 2' cc appears to be very nearly unity for hydroly-ticreactions catalysed by enzymes28-a result which allows us toeliminate one of the many explanations possible for the arrestingeffect of heavy water on the growth of organisms.29The relatively simple technique required to measure the surfacepotential of films 30 is a new and powerful implement in the handsof the investigator, enabling him, as it were, almost to touch themolecules which are reacting. With investigations of the hydrolysisof proteins,31 the oxidation of fatty the saponification ofe~ters,~3 and the polymerisation of unsaturated thesubject of chemical kinetics in two dimensions may be said to havebegun .35Remarks on the Semi-empirical Pactor, P.-The velocity constantfor bimolecular reactions may be written in the form li: = PZe-E/R1l,where 2 is the collision frequency.In the case of simple reactions,P gives the probability that an energetically satisfying encounterleads to chemical change. The meaning of P, often called the" steric " factor, is in other cases more obscure, and must be discussedbriefly. We shall accept the value of 2 given by the kinetic theoryof gases, although the use of formulae differing from it both inform 361 37 and in order of magnitude 383 l6 has been advocated.P is known to be unity for some hundreds of reactions in solutionand for some tens of reactions in gases.It may also be as highas lot9 or as low as 10-9. Reactions are said t o have normal,fast, or slow rates, according as P equals, exceeds, or is less than 1.When two comparable reactions have different rates, experimentshows that the difference may be due to a change in E, in P, or inboth. For example, when hydrogen chloride is replaced by hydrogenbromide in the chloroacetanilide reaction,39 the 20,000-fold increasein speed is due almost entirely to a, change in E . When an ionicreaction is compared with the corresponding non-ionic one, it oftenhappens that E remains constant while P, is about 1 and Po is2 7 L.J. Halford, L. C. Anderson, J. R. Bates, and R. D. Swisher, J . Amel..Chem. SOC., 1935, 57, 1663.28 E. W. R. Steacie, Z . physikal. Chem., 1934, [ B ] , 27, 6 ; 28, 236.z9 0. Reitz and K. F. Bonhoeffer, ibid., 1934, 17'2, 369; 1935, 174, 424.30 A. IT. Hughes, J. H. Schulman, and E. K. Rideal, Nature, 1932, 129, 21.31 J. H. Schulman and E. K. Rideal, Biochem. J., 1933, 27, 1581.32 A. H. Hughes and E. K. Rideal, Proc. Roy. SOC., 1933, [A], 140, 253.33 R. J. Fosbinder and E. K. Rideal, ibid., 1933, [ A ] , 143, 61.34 See Ref. 71. 35 Cf. E. J. Bowen, Ann. Reports, 1934.36 J. K. Syrkin, Acta Ph3sicochirnica U.R.S.S., 1935, 1, 855.37 R. S. Bradley, J., 1934, 1910.s8 M. C. Evans and M. Polanyi, Zoc. cit., ref. (16), p.94.$9 I. Jones and F. G, Soper, Proc. Roy, BOG, 1934, [A], 144, 643BlO.lkLWYN-HJJGHES : (IEEMICAL ICINETICS. 107lower by several powers of ten. Concurrent changes in P and Eare very common.There has been no lack of ideas in attempting to interpret P.Some of the earlier conjectures were disproved by the experimentsof Hinshelwood and Moelwyn-Hughes (19321, who pointed out newpossible meanings which may be attached to it. There are threeaspects of recent discussions.(1) The geometric factor, which aims a t allowing for orientationefTects. Opinions on the possible extent of this contribution varylargely. It should, perhaps, be pointed out that the effect is to someextent automatically allowed for in the dynamical formulation ofthe problem.@ J.M. SturtevantY4l on theoretical grounds, con-cludes that the orientation effect is not large enough to allow for therelatively minor deviations from the laws of Bronsted and LaMer.42With different experimental systems, on the other hand, A. T.Williamson and C. N. Hinshelwood43 consider that a factor of theorder of '' could reasonably be explained on the basis of thesimplest kind of steric considerations "-a view which is endorsedby R. P. Bell and (Sir) R. V. H. Levinge.44( 2 ) The transmission probability, G, which, according to H. Hell-mann and J. K. S ~ r k i n ? ~ can be considerably smaller than 1, evenfor massive particles, provided G is computed for each discretestate. Thus the ease with which the nitrogen atom in ammoniacan pass to and'fro through the plane of the three hydrogen atomsappears to be sensitive t o the degree of sharpness of the quantis-ation of vibrational energy.(3) The entropy change, S.Drawing on thermodynamicalanalogy, we may anticipate that E varies linearly with the temper-ature ( E = E, + XT), in which case P includes a term es/B. Inprinciple, X can be found from the temperature variation of E orfrom the postulated structure of the critical complex (Soper,22L;lrMer,22 Rodebush, l5 Wynne- Jones and Eyring 21). Provided welrnow the actual equilibrium data for reactants Z resultants,as distinct from the hypothetical equilibrium data for reactants zzreactive complex, we can eliminate the unknown term involvingthe entropy of activation, and obtain expressions for the velocity40 R.C. Tolman, " Statistical Mechenics," p. 67, 1927.4 1 J . Chem. Ph98iC8, 1935, 3, 295.42 A full account of these laws, and of salt effects in general, was given bySubsequent developments have43 Trans. Paraday SOC., 1934,30, 1145; A. C. Rolf0 and C. N. Hinshelwood,44 proc. Roy. SOC., 1935, [A], 151, 211.4s ACta Ph,yeico~himka U.R.S.S., 1935, 8,433.R. p. Bell in the Annual Reports for 1934.been hardly sufllcient to warrant discussion here.ibid., p. 935108 GENERAL AND PHYSICAL CHEMISTRY.of reaction which include only measurable entropy terms. A fairtest of the theory in this least speculative form has been carriedout by F. G. Soper 46 for bimolecular reactions in the gaseous phaseand in solution. There is satisfactory agreement for cases with Pdiffering as widely as 1 and 10-7. According to Soper, P alwaysapproximates to unity for reactions attended by an increase inentropy.The theory, therefore, applies in particular to slowreactions, the outstanding examples of which were shown, some yearsago, to be highly exothermic.A method of factorising the more complicated term P for uni-molecular reactions has been suggested by C. N. Hinshel~ood.~~In addition to the geometric contribution, and a correction termsuperimposed on the Boltzmann factor, a third term a/S is intro-duced, where CI. is the rate at which energy in the preactivated mole-cule flows into the requisite bond, and is the rate a t which it flowselsewhere, i.e., is dissipated.The internal redistribution of energyhas also been the topic of an organised discu~sion.~~Organic Reactions.-We must regrettably confine ourselves to amere categorical list of selected organic reactions which have beenstudied with sufficient care to allow the detection of even smallchanges in P or in E. Apart from the unimolecular decompositionof nitrites, and the cis-trans-isomerism of stilbene, methyl cinnamate,and methyl maleate,48 the study of reactions in families has been con-fined to bimolecular reactions in solution. In the following examples,each consists of about twelve members : reactions of aryl and alkylchlorides with ethyl alcohol in various solvents ; 49 saponification ofesters of different substituted phthalic 5* and crotonic acids; 51reactions between hydrogen bromide and alcohols in phenol solution ; 52reactions between bases and p-C,H4R*CH,Br in various solvents ; 53organic esterifications ; 54 the union of arnines with halides in benzenesolution ; 55 the hydrogen-ioii catalysed prototropy of nuclear sub-46 J ., 1935, 1393.4 7 C. N. Hinshelwood, J. E. Lennard-Jones, M. Travers, 31. Polanyj, C.Zener, E. J. Bowen, R. C . W. Norrish, H. W. Thompson, C. J. M. Fletcher,E. K. R$idenl, and A. R. Ubbelohde, Proc. Roy. Soc., 1934, LA], 146, 239.4 8 G. B. Kistiakowsky and W. R. Smith, J . Amer. Chem. Soc., 1935,57, 269.49 J. F. Norris, E. V. Vasee, and J. C. J. Staud, ibid., p. 1415; J. F. Norrisand H. H. Young, &id., p. 1420; J. F. Norris and E. C. Haines, ibid., p.1425.60 G.Semerano, Gazxetta, 1935, 65,252.5 1 E. Schjanberg, 2. physikal. Chem., 1935, 174, 465.52 G. M. Bennett and F. M. Reynolds, J., 1935, 131.53 J. W. Baker and W. S. Nathan, ibid., p. 519.54 C. N. Hinshelwood and A. R. Legard, ibid., pp. 587, 1588.6 5 C. A. Winkler and C. N. Hinshelwood, ibid., p. 1147MAXTRD : SURFACE CHEMISTRY. 109stituted acetophenones, 56 which affords an additional illustration ofNathan and Watson’s rule (1933) ; and the action of alkali on bromo.ethanes and chl~roethanes.~~ The theory of tlhe constitutional effectsupon the kinetics of organic reactions has been developed con-siderably in the light of new work.58 The distinction between organicand physical chemistry, perhaps seldom more than a convention,seems to vanish completely when we find that mesomerism, forexample, may be directly interpreted as a resonance effect betweenmolecules possessing normal and polar structure.69E. A.M.-H.6. SURFACE CHEMISTRY.A considerable and increasing amount of work has been done inthis field during the period under review. It is difficult to selectsections for special comment ; but outstanding interest is perhapsattached to the nature of adsorption processes of chemical or so-called “ activated ” type and to the degree to which those of slowerform are due to penetration effects; also to the recognition andmeasurement of the energy barriers which are involved in theactivated migration theory which has recently been put forward byE. K. Rideal. Further, in heterogeneous catalysis, the attemptedanalysis by H.zur Strassen and Q. M. Schwab of the factors whichare contributory to the apparent energies of activation appearsundoubtedly an important step towards the attachment of somedegree of precise significance to the experimental values of thoseenergy terms which are obtained on the basis of the temperaturecoefficient.Adsorption Components.-In certain cases of adsorption, theprocess is obviously composite and consists-in addition to low-temperature adsorption of van der Waals type-of a relativelyrapid component, which in all probability involves linkage of apurely chemical nature, and of a slower process which takes placeconcurrently with or subsequently to the primary process. Thissharply differentiated, very rapid component is especially character-istic of the adsorption of hydrogen and of certain other gases bymetals, such as platinum or nickel, which are active for catalytic66 D.P. Evans, IT. G. Morgan, and H. B. Watson, J . , 1935, 1167, 1174.6 7 W. Taylor, ibid., p. 1514; W. Taylor and A. M. Ward, J., 1934, 2003.5 8 J. L. Gleave, E. D. Hughes, and C. K. Ingold, J., 1935, 236; E. D.Hughes and C. K. Ingold, ibid., p. 344; E. D. Hughes, ibid., p. 255; C. K.Ingold and H. G. G. Mohrhenn, ibid., p. 1482 ; L. P. Hammett, Chem. Reviews,1935, 17, 125.59 C. K. Ingold, ibid., 1934, 15, 2 2 5 ; H. B. Watson, W. S. Nathan, andL. L. Laurie, J , Cltem. Physics, 1935, 3, 170110 GENERAL AND PHYSICAL CHEMISTRY.hydrogenation. In other cases, e.g., in the adsorption of manygases on adsorbents of oxide type, this distinct rapid component isless pronounced or absent.In the last Report in which a review of the progress of surfacechemistry was included (1931), an account was given of H.S.Taylor's conception of activated adsorption. This has in themeantime been developed in a number of papers ; and the treatmentof the subject has become less simple by the apparent presence, inmany cases, of more than one activated component. Thus H. S.Taylor and C. 0. Strother,l who continued the work of H. S. Taylorand D. V. Sickman,2 have put forward, in connexion with theadsorption of hydrogen on zinc oxide, evidence for two activatedadsorption processes, in addition to van der Waals adsorption.The first of these activated processes takes place between 0" andabout loo", and is associated with an activation energy of the orderof 5 kg.-cals.The second, which begins at about 100" and is stillmeasurable at about 300", has an activation energy of about 12 kg.-cals. Physical adsorption took place up to about - 80" ; and therewas no measurable adsorption of this type at or above room temper-ature. With zinc oxide promoted with chromium oxide, whichis a more active catalyst, the existence of only one form of activatedadsorption, beginning at - 78", was deduced; and this low initialtemperature is regarded as being indicative of an extremely lowactivation energy. The calculated values of these activationenergies vary with the conditions : for instance, J.Howard andH. S. Taylor 3 found that the apparent energy of activation of theactivated adsorption of hydrogen on chromium oxide varied, withthe sample of oxide studied, from 14 kg.-cals. to about twice thisvalue and increased with the degree of covering. A similar apparentincrease in the critical increment with the adsorbed concentrationhas been observed by P. V. McKinney for hydrogen on manganesechr omite .If the adsorption of hydrogen or of another reducing gas on anoxide is involved, the possibility of the reduction of the oxide isalways present. There appear, however, to be good grounds forassuming in many such cases the prior formation of an adsorptioncomplex, which breaks down, on being further heated, into thenormal reduction products; and the total reaction may thus beregarded as including an initial process of irreversible adsorption.McKinney has investigated from this standpoint the adsorption ofJ .Amer. Chem. SOC., 1934,56, 586; A,, 1934, 484.Ibid., 1932, 54, 602; A . , 1934, 458.Ibid., 1934, 56, 2259; A., 1935, 28.J . Physical Chem., 1933,37,381; A., 1933,471MAXTED : SURFACE CHEMISTRY. 11 1carbon monoxide by palladium which is only slowly reducedby this gas even at 100". At - 80" the adsorption was almostentirely of the physical type ; but irreversible activated adsorptionbegan at about 0" and increased with increasing temperature to amaximum at about 110", beyond which temperature adsorptiondecreased. The isobar thus showed all the normal characteristicsof activated adsorption.Evaporation of the adsorbed gas only tookplace in the form of carbon dioxide. McKinney calculated theapparent energy of activation of the adsorption process, but regardsthe wide variation in the values obtained (2.6-16 kg.-cals.) as anindication of the complex nature of the adsorption. The formationof irreversible adsorption complexes has also, for instance, beenpostulated by W. E. Garner and F. J. Veal in the adsorption ofcarbon monoxide on a zinc chromite catalyst ; and a slightly differenttype of irreversible activated adsorption is represented by thework of W. W. Russell and L. G. Ghering on the adsorption ofoxygen by nickel at low temperatures.'Since the subject is not complicated by the possibility of reduction,the investigation of activated adsorption +on metals is of specialinterest.R. W. Harkness and P. H. Emmett have adducedevidence for two types of activated adsorption, in addition tophysical adsorption, for hydrogen on promoted ammonia catalysts ;and J. Turkevich and H. S. Taylor9 have examined, from thestandpoint of an activated compoiient, the adsorption of ethyleneon hydrogenating catalysts both of metallic and of oxide type.With manganese chromite, the adsorption of ethylene at or below0" is principally of the van der W&als form. At 110" there was, inaddition, some activated adsorption. With copper, activatedadsorption occurs a t a much lower temperature, vix., even at 0".The isotherms for both types of catalyst were of the form in which theadsorption rises continuously with increasing pressure. A furtherexample of a somewhat similar nature to the already cited adsorp-tion of oxygen by nickel is its adsorption by platinum.H.Reischauer lo obtained, with compact platinum, indications of twotypes of activated adsorption, which are associated with differentactivation energies and occur at different ranges of temperature.The conception of activated adsorption, in which the interactionbetween the gas and the adsorbent is regarded as being composed ofactivated surface processes, has been criticised by many investig-J . Amer. Chem. SOC., 1933, 55, 3626; A., 1933, 913.7 J . Amer. Chem. SOC., 1933, 55, 4468; A., 1934, 22.Ibid., p. 3496; A., 1933, 1018; 1034, 56, 490; A., 1934, 371.9 Ibid., 1934, 56, 2254; A ., 1934, 28.10 2. physikaZ. Chem., 1934, [B], 26, 399 ; A,, 1934, 1303,J., 1936, 1487112 GENERAL AND PRYSICAL CKEMISTRY.ators. For instance, Garner and Veal l1 consider that there is butlittle evidence that this type of adsorption is controlled by activationenergy inherent in the adsorption process itself. Certainly, thedegree of significance of the widely varying values which areobtained, on thk basis of the temperature coefficient, for theapparent activation energy needs further definition ; and much is tobe said for Garner and Veal's preference for the older designation,chemisorption, to indicate the nature of the linkage and to dis-tinguish such processes from physical adsorption, rather than theapplication of the term '' activated " to processes for which therate-control by activation energy of adsorption is still a matter onwhich agreement has not been reached.In this connexion, the degree of influence of any penetrationef-fects in the total slow adsorption process is still to be considered.This aspect was discussed by E.W. R. Steacie,12 A. F. H. Ward,13and J. E. Lennard-Jones7l4 as already reported,l5 and also byS. Iijima,16 who concurs in the view that the rate curves obtainedfor hydrogen on, e.g., finely divided nickel indicate adsorptionfollowed by diffusion. The subject of penetration has more recentlybeen developed by E. K. Rideall' in collaboration with H. W.Melville.l* The total adsorption is regarded as consisting of a tleast three processes involving energy barriers, vix., the passagefrom van der Waals adsorption to chemisorption, migration fromjust outside to just inside the surface, and internal migration.Evidence was adduced, in the course of work with hydrogen andwith deuterium, for the existence of a definite energy barrier for thepenetration of these gases from the surface t o the interior of copper,as well as for migration within the metal.Accordingly, the slowadsorption process, which proceeds with an apparent energy ofactivation, is apparently a composite reaction; and any data,e.g., for the activation energy, only acquire significance if the degreeof incidence of each component can be determined. The surfacefactor in these composite processes may be recognised from manyobservations.J. Howard lg found that the high-temperaturechemisorption of hydrogen on chromium oxide gel markedly11 LOC. cit., ref. (6).l2 J . Physical Chem., 1931, 35, 2112; A., 1931, 904.l3 Proc. Roy. SOC., 1931, [ A ] , 133,506,522 ; A., 1931, 1365 ; T'runs. ParadaySOC., 1932, 28, 399; A., 1932, 688.l4 Ibid., p. 333; A., 1932, 688.l6 Sci. Pupers 1 s t . Phys. Chem. Res. Tokyo, 1933, 22, 285; 23, 34; A.,l7 Nature, 1935,135, 737; A., 818.Proc. Roy. SOC., 1935, [ A ] , 153, 77, 89.l9 Nature, 1933,132, 603; A., 1933, 1112.l5 Ann. Reports, 1931, 28, 37, 38.1934, 139, 358MAXTED : SURFACE CHEMISTRY. 113diminishes the van der Waals adsorption, from which he concludesthat the slow high-temperature process is a t least in part a surfacephenomenon.P. H. Emmett and R. W. Harkness20 reach thesame conclusion from the effect of previous high-temperatureadsorption on the rate of the ortho-para conversion of hydrogen onplatinum or nickel at - 190" and from a study of adsorption oniron-ammonia catalysts .21Heat of Adsorption.-In calorimetrically determined adsorptionheats, the effect measured will, in cases such as the adsorption ofhydrogen by metals, represent principally that due to the rapidcomponent; and, in view of the difficulty in previously removingthe last traces of adsorbed gases without exposure of the adsorbentto a temperature sufficient to modify its normal surface properties,the initially observed differential heat will not, in general, be thetrue threshold value. This is especially the case for hydrogenatingcatalysts such as platinum or nickel.If, on the other hand, theadsorption heat is calculated by means of the Clausius-Clapeyronequation, the significance of the result will depend on the attainmentof true equilibrium and on the effective simplicity of the adsorptionstudied.In exceptional cases, however, threshold values for the adsorptionheat may be measured. J. K. Roberts,22 who used the value ofthe thermal accommodation coefficient of neon as an indication ofthe degree of bareness of a tungsten filament, previously flashed ata temperature above 2000", has calculated a threshold heat ofabout 45 kg.-cals. per mol. of hydrogen for the adsorption of thisgas on tungsten.The adsorption heat subsequently decreases toa limit of about 18 kg.-cals. for a completely covered tungstensurface, the decrease being regarded as due to the nature of theadsorption process and not necessarily to any heterogeneouscharacter of the surface. The adsorption was practically instan-taneous, even at pressures of 10-4 mm. or less.Under the conditions which obtain when the adsorption heat ismeasured for a previously degassed catalytically active metal, thesurface is already, in general, partially covered ; and the apparentlyconstant values for the differential adsorption heat which havebeen obtained by various investigators 23 for hydrogen on copperor platinum, or for oxygen on platinum, may be due to the restrictedadsorption range imposed by the limitations of degassing, or to a2o J.Arner. Chern. SOC., 1935, 57, 1624; A , , 1329.21 Ibid., p. 1631; A., 1315.22 Proc. Roy. SOC., 1935, [A], 152, 445.2s A. F. H. Ward, Zoc. c i t . ; R. A. Beebe, Trans. Faraday SOC., 1932, 28,761; A., 1932, 1199; E. B. Maxted and N. J. Hassid, J., 1931, 3313; A.,1932, 118; Trans. Faraday SOC., 1933, 29,688; A., 1933, 911114 C,ENERAL AND PHYSICAL CHEMISTRY.difference in the adsorptive properties of finely divided metalliccatalysts and a previously heated compact metal filament. Forcarbon monoxide on reduced copper, R. A. Beebe and E. L.Wildner 24 observed an adsorption heat which decreased with tbeadsorbed concentration. It may be noted that, in a, compositeadsorption, an increased degree of incidence of slower and lessexothermic components as the adsorbed concentration is increased,would, under the conditions of calorimetric measurements, in itselfcause a fall in the observed heat as the degree of covering is increased.In any case, the direct determination of adsorption heats presentsconsiderable experimental difficulty. Possible sources of error havebeen discussed by Ward and by others of the above workers, alsoby G.M. Schwab and W. Brenne~ke.~b Note may also be made ofa particularly accurate form of calorimeter which has recently beendescribed by W. E. Garner and P. J. The direct measure-ment of the adsorption heat of hydrogen and of carbon monoxideon zinc oxide and on zinc chromite in this apparatus gave evidenceof two types of adsorption for the latter adsorbent, which was alsoemployed in the partially reduced state, namely, an irreversibleadsorption, associated with a heat of about 45 kg.-cals., whichtakes place on the oxidised surface, and, on the reduced surface, areversible adsorption having a heat effect of 10-15 kg.-cals.As an example of a system containing a metallic adsorbent andin which the conditions permit the thermodynamic calculation ofthe adsorption heat, the adsorption of oxygen on silver may bementioned.A. F. Benton and L. C. Drake27 have calculated inthis way a value of about 13 kg.-cals. for the adsorption at about190", at a pressure such that the formation of silver oxide is pre-cluded. Frequently, however, with metals, this indirect method ofcalculation is inapplicable owing either to non-attainment ofequilibrium or to lack of knowledge with regard to the effectivesimplicity of the adsorption.Calculation by means of the Clausius-Clapeyron equation can,however, be applied to many adsorbents of oxide type. H.S.Taylor and D. V. Sickman28 obtained by this method a value of1.1 kg.-cals. for the physical adsorption of hydrogen on zinc oxideat low temperatures, and about 21 kg.-cals. for the adsorptionprocess which takes place at about 450". Purther, as an instance ofa relatively high-temperature adsorption accompanied by a far24 J . Amer. Chern. SOC., 1934, 56, 642; A., 1934, 485.2 b 2. phyaikal. Chem., 1932, [ B ] , 16, 19; A., 1932, 459.ae J., 1935, 1436, 1487.a7 J .Amer. Chem. SOC., 1934,56,256; A , , 1934,370,28 Ibid., 1932, 34, 602; A. 1932,458MAXTED : SURFACE CHEMISTRY. 115smaller heat effect, B. Neumann and E. Goebel 29 have attemptedto estimate the influence of temperature on the heat of adsorptionof oxygen on iron oxide. Grebt accuracy was not possible, but theadsorption heat apparently fell from 2.2 kg.-cals. for a temperaturerange of 20-100" to 1-3 kg.-cals. when the upper temperature wasincreased to 300".Structure of Solid Adsorbing and Catalysing Surfaces.-In earlierReports reference has been made to H. S. Taylor's theory of surfaceheterogeneity based on the postulated occurrence of extra-latticeprojections or peak areas which are associated with special activity.This important conception of extra-lattice projections has beendiscussed by a number of workers.0. Schmidt 3O mentions in thisconnexion G. Tammann and W. Boehme's observation3l thatsmall particles of metals--e.g., small rods or films of gold, for instanceof an order of thickness of 4p, at 200O-have only a very short lifeand disappear through sintering, by virtue of differences in vapourpressure, an effect which must be even more intense with extra-lattice projections of molecular dimensions. Again, E. Fajans 32has shown, and it is a matter of general experience, that a veryshort sintering period is sufficient to stabilise a nickel surface insuch a way that it does not change in activity even on prolongedfurther exposure to temperatures up to the sintering temperature.Evidence for the effective uniformity of a metallic catalysingsurface has been put forward by E.W. R. Steacie and E. M. Elkin,33who have shown that there is no discontinuity at the melting pointin the activity of zinc when this metal is used as a catalyst for thedecomposition of methyl alcohol between 360" and 440°, from whichit is concluded that the whole surface is uniformly active and thatthe catalytic activity is not limited to a part only; for, if activecentres are involved in the catalytic reaction on solid zinc, it wouldbe expected that there would be a sudden and very large drop inthe activity at the melting point. The equivalence of the catalysingsurface elements has also been discussed by G.M. S~hwab,~* whoconsiders, on reaction-kinetic grounds, that catalysis is carried outby a range of energetically homogeneous points. Further evidencemay, moreover, be obtained 35 from the effect of progressive poison-2. Elektrochem., 1934, 40, 754; A., 1935, 28.30 Ber., 1935, [B], 68, 1098; A., 940.31 Ann. Physik, 1932, [v], 12, 820; A,, 1932, 452.32 2. physikal. Chem., 1935, [B], 28,252.33 Proc. Roy. SOC., 1933, [A], 142, 457; A., 1934, 38.34 2. physikal. Chem., 1934, 169, 81 ; 171, 421.35 E. B. Maxted and G. J. Lewis, J., 1933,502 ; E. B. Maxted and V. Stone,ibid., 1934, 26, 672; E. B. Maxted and C. H. Moon, ibid., 1935, 393; E. B.Maxted, J. SOC. Chem. Ind., 1934, 53, 102T; A., 1933, 680; 1934, 262, 607,851; 1935, 589116 GENERAL AND PHYSICAL CHEMISTRY.ing and of deactivation by heat treatment, and by a re-examinationof G.Vavon and A. Husson’s work 36 on step-wise deactivation.Although many observations apparently indicate the effectiveequivalence of the catalysing range of surface elements, yet theextension of this to equivalence throughout the whole range ofadsorbing points is bound up with the question as to whetherall adsorbing points are equally effective for catalysis. Steacieand Elkin’s work on the absence of discontinuity in activity atthe melting point of a solid catalyst would appear to show thatthis is so, a t any rate in the case investigated; but this extensionis not in conformity with Pease and Stewart’s observation 37 of thenon-correspondence between the depression of catalytic activityand adsorptive capacity which is caused by partial poisoning;and further investigation is undoubtedly still required.Thelimited degree of equivalence, namely, that of the catalysing points,is, however, not incompatible with the adlineation theory of Pietschand S ~ h w a b . ~ ~Heterogeneous Catalysis.-It is becoming more and more evident,that heterogeneous catalytic reactions are processes the mechanismof which is complicated, not only by the presence of a transitionstate, but also by composite adsorption effects. For this reason,activation energies calculated by applying the simple Arrheniusrelationship have little significance, unless the conditions are suchthat they refer to a dominant stage.In this connexion, attention may be drawn to an activationmechanism which has been proposed by E.C. C. B a l ~ , ~ ~ accordingto which the total critical increment required in a heterogeneouscatalytic reaction is supplied in two stages. G. H. Bottomley,B. Cavanagh, and M. Polanyi40 also consider that such reactionstake place in two stages, the second being the slower and thereforethe rate-determining process. This is suggested, further, in Horiutiand Polanyi’s treatment of the part played by nickel or anothercatalyst in the hydrogenation or hydrogen-deuterium exchange ofethylene or benzene.41 In any case, a mechanism which involves36 Compt. rend., 1922, 175, 277; A., 1922, ii, 631.37 R. N. Pease and L. Stewart, J . Amer. Chewi. Xoc., 1925, 4’4, 1235; A .,1926, ii, 691.3* E. Pietsch, A. Kotowski, and G. Berend, 2. physikal. Chem., 1929, [BJ,5, 1 ; A . , 1929, 1150; G. M. Schwab and E. Pietsch, 2. Elektrochem., 1929,35, 135; A . , 1929, 519; G. M. Schwab and L. Rudolph, 2. physikal. Chem.,1931, [B], 12, 427; A., 1931, 919.39 Nature, 1935, 136, 146; A., 1084.40 Ibid., p. 103; A., 1084; see also J. Horiuti and M. Polanyi, Proc.41 Trans. Parndciy SOC., 1934, 30, 1164; d., 1934, 1077.Jlnnchester Lit. Phil. SOC., 1934, 78, 50MAXTED : SURFACE CHEMISTRY. 117the formation of an intermediate adsorption complex appears to begenerally applicable. A surface may, in exceptional circumstances,promote reaction outside the adsorbed phase, for instance by theinitiation of chain reactions.42 The degree of gaseous chain initiationwhich was claimed by K.Bennewitz and W. Neumann 43 in ordinarycatalytic reactions such as in the hydrogenation of ethylene onplatinum appears, however, to be unfounded ; 44 and heterogeneouscatalytic reactions of the usual type may probably be regarded asbeing effectively confined to the adsorbed phase.The relative influence of the various adsorption components onthe reaction velocity has continued to receive attention, particularlyfrom the standpoint of the catalytic importance of the slowerforms of adsorption. Thus, J. Howard and H. S. Taylor 45 considerthat the activated adsorption of ethylene is the rate-determiningfactor in the hydrogenation of ethylene on catalysts of the oxidetype; and P. H. Emmett and 8.Brunauer46 regard the slowadsorption of nitrogen by various ammonia catalysts as being thecontrolling step in the synthesis. Chief interest is attached tocases where a relatively rapid and a relatively slow adsorptioncomponent, each of which constitutes a source of supply of the samemolecular species, occur concurrently. M. Polanyi’s theory of themechanism of catalytic hydrogenation 47 requires that the cata-lytically active adsorption should be not a strong, but an extremelyweak, activated adsorption; and, where there are, side by side, aslow activated adsorption, of high apparent activation energy, anda rapid adsorption, of low activation energy, on the same catalyst,the catalysed reaction should, according to the above conception,proceed through the latter and not through the former.An exampleof this is to be found in the observation of A. J. Gould, W. Bleakney,and H. S. Taylor 48 that the interaction of hydrogen and deuteriuma t low temperatures takes place far more rapidly than the rate ofactivated adsorption.The degree of influence of a dominant adsorbed species, togetherwith the utilisetioii of the heat of association as a contributoryfactor towards the activation energy, has been developed by H. zurStrassen 49 and by G. M. Schwab 50 in connexion with the passage42 See e.g., M. W. Travers, Nature, 1935, 136, 909.43 2. physikal. Chew&., 1930, [B], 7, 247; A., 1930, 715.44 K. Bennewitz and W. Noumann, ibid., 1932, [B], 17,457; A , , 1932, 818.45 J . Amer. Chem.Xoc., 1934, 56, 2259; A., 1935, 28.46 Ibid., p. 35; A., 1934, 262.47 J . SOC. Chem. Ind., 1935, 54, 1 2 3 ~ ; A., 711.48 J . Chem. Physics, 1934, 2, 362; A., 1934, 1074.49 2. physikal. Chem., 1934, 169, 81; A., 1934, 974.Ibid., 1934, 171, 421; A., 1935, 441118 GENERAL AND PHYSICAL CHEMISTRY.of a reaction velocity through a maximum value as the reactiontemperature is increased-with subsequent production of a negativetemperature coefficient-and as an alternative to ascribing thisnegative coefficient to a decrease in adsorbed concentration. Thus,in the hydrogenation of ethylene on nickel, the variation of thereaction velocity with temperature is represented by an expressionof the formin which 7c is the reaction velocity, E the activation energy ofthe hydrogenation reaction, QH2 and QCaH, the heats of adsorptionof the hydrogen and of the ethylene, and a st factor involvingadsorbed concentrations.According to the views of these authors,the reversal takes place at a temperature at which adsorption ofthe ethylene, together with its heat of adsorption, begins to be aneffective factor in the kinetics. A similar treatment has also beenapplied in connexion with the reversal in the sign of the temperaturecoefficient in the hydrogenation of crotonic and maleic acids in adissolved state in the presence of platin~m.~lWhile a further examination of the controlling mechanism postul-ated by zur Strassen and Schwab is obviously needed, since othermethods of control are possible, their treatment of these cases ofreversal appears both suggestive and-provided that it can beconfirmed-capable of wider application.Certainly, without somemodification in the Arrhenius equation for these heterogeneousreactions, the calculated values for the activation energy are ofrather indefinite significance.An alternative view to the above aspect of the reversal has beenput forward by T. Tucholski and E. K. Ridea1.52 These authorsfind that hydrogen and deuterium reduce ethylene a t equal ratesin the high-temperature region,53 from which it is pointed out thatthe rate is probably determined by some reaction involving thehydrogen which does not involve a zero-point energy difference;and control by activated migration, probably of hydrogen, issuggested.A further alternative, which Tucholski and Ridealconsider less probable, is control by a reaction involving identicalenergies of activation for the ethylene, the negative temperaturecoefficient being due to its desorption. R. Klar 54 also observed areversal in the hydrogenation of ethylene with both isotopes in thepresence of an iron catalyst. At temperatures up to about 100"= ae- KE - QHJ - QC2HJI RT51 J., 1935, 1190; A., 1210.53 See R. N. Pease and A. Wheeler, J . Amer. Chem. SOC., 1935, 57, 1144;54 2. physikal. Chem., 1934, [B], 27, 319; A., 1935, 175.Ibid., p. 1701.A., 938MAXTED : SURFA(!E CHEMISTRY. 119deuterium reacts with ethylene more slowly than hydrogen, but,above this temperature, a more rapid reaction with the heavyisotope took place.With deuterium, the maximum velocityoccurred at about 150°, whereas, with hydrogen, reversal tookplace at about 125".Some work has been done on the mode of activation of catalysts bysecondary constituents. For instance, an interesting study of thenature of the association between the constituents of a number oftwo-component catalysts has been made by G. Wagner, 0. M.Schwab, and R. Staeger.55 I n cases in which an abnormal increasein catalytic activity-compared with the activity of each of thecomponents separately-occurs, X-ray analysis shows evidence forchemical association between the components, in contrast to theoccurrence of the lattice structure of each of the componentsseparately in other cases. Thus, Cu0,ZnO and Cu0,MgO gavediagrams showing no association, whereas CuO,Cr,O, and CuO,Al,O,showed the formation of a new complex with the possibility of newadsorptive properties.Similarly, A. Mittasch and E. Keunecke 56have obtained evidence, on chemical grounds and as the result ofX-ray examination, of the formation of mixed crystals of alumina,and ferric oxide in the promotion of iron-ammonia catalysts withalumina. These authors infer that one function of the promoter isto inhibit the reduction of the iron oxide. J. Eckell 57 found thatthe apparent activation energy of an iron oxide catalyst promotedwith an increasing concentration of alumina decreased linearlywith the alumina concentration up to a content of about 25%, andthis was accompanied by a parallel change in the lattice structure.Of the catalytic reactions which have been studied during theperiod under review and which possess special general significance, abrief reference may be made to catalysed processes involvingdeuterium, for which, as would be expected, the same catalysts canbe employed as for the lighter isotope.The saturation of ethyleneby deuterium in the presence of metallic catalysts has already beennoticed. K. Morikawa, W. S. Benedict, and H. S. Taylor 58 haveused nickel for the deuterium-hydrogen exchange in methane.J. Horiuti, G. Ogden, and M. Polanyi 59 found that substitutiontook place on shaking benzene with deuterium in the presence ofnickel or platinum; although these substitutions also occur in theabsence of a catalyst.60 The somewhat similar process of exchange6 5 2.physikal. Chern., 1934, [B], a, 439; A., 1935, 455.56 2. Elektrochem., 1932, 38, 666; A . , 1932, 1004.5 7 Ibid., p. 918; 1933,39,855; A., 1933, 131, 1253.68 J . Amer. Chern. SOC., 1935,57, 592; A., 688.6Q Trans. Paraday SOC., 1934, 30, 663; A., 1934, 973,6o Nature, 1934, 134, 734; R., 1935, 74120 GENERAL AND PHYSICAL CHEMISTRY.of atoms between water and deuterium may also be catalysed byplatinum-black.6lI n the above review, no attempt has been made to deal with themany catalytic reactions which are of interest principally in relationto the process involved, rather than from a general standpoint,since such catalytic processes are more logically considered in thesection appropriate to the reaction in question.E.R. M.7. THE PHYSICAL BASIS OF OPTICAL ROTATORY POWER.The progress which has recently been made towards the elucid-ation of the problem of the origin of optical rotatory power hasculminated during the present year in an important paper byM. B0rn.l Current theories may be divided into two classes,“ electronic ” and “ molecular,” but they have a common basis inthe theory of coupled vibrators, proposed by M. Born in 1915,2according to which a molecule may be represented by a system ofelectrical particles which are more or less rigidly fixed relative toone another but become polarised (Le., undergo small displacements)under the influence of an applied electric field, such as the electricvector of a plane-polarised light wave.When one particle is setin vibration, it sends out secondary waves which act on the otherparticles just as the primary light wave does, and this process isrepeated from particle to particle. If the particles are isotropic,rotation of the plane of polarisation can appear as a third-ordereffect when not less than four of them have taken part in theresonance process, or when two have taken part if they areanisotropic; but only on the condition that the four particles donot lie in the same plane in the former case, and that, in general,the system has no plane or centre of symmetry. This is a mathe-matical statement of the principle of molecular dissymmetry,but unfortunately, the detailed analysis in the general case isextremely complicated, and involves parameters which are notdirectly accessible to physical or chemical measurement.Sub-sequent developments have therefore consisted in the introductionof simplifying assumptions, and the difference between the electronicand the molecular theory lies only in the nature of the simplificationswhich they involve.61 S. Horiuti and M. Polanyi, Nature, 1933,132, 819; A., 1934, 17.1 Proc. Roy. SOC., 1935, [ A ] , 150, 84.2 Physikal. Z., 1915, 16, 251, 437; Ann. Physik, 1918, [iv], 55, 177. Seealso M. Born and P. Jordan, “ Elementare Quantenmechanik,” 1930, 260 ;M. Born, “ Optik,” 1933ALLSOPP : PHYSICAL BASIS OF OPTICAL ROTATORY POWER. 121(i) W. Kuhn applied the principle of coupling to a molecularmodel consisting of two hear (i.e., completely anisotropic)vibrators which are constrained to move only in directions perpen-dicular to one another along axes separated by a vertical distance d(Fig.3a), the optically active medium being treated as a collectionof such models in random orientation. Under these conditions,optical activity is promoted from a third-order t o a first-ordereffect, with a consequent reduction in mathematical complexity.For wave-lengths remote from an absorption band, formulz areobtained which are identical with those of Drude or of Natanson,but they have the merit of being consistent with the model, whereasW. Kuhn4 shoked that Drude’s conception of spiral oscillatorsdoes not actually lead to rotatory power a t all. Kuhn’s model,however, itself needed modification, since the value of d derived forit from measurements of circular dichroism (see below) proved inmany cases to be incompatible with the known molecular dimensions ;but W.Kuhn and K. Bein were able t o show that activity of thecorrect order of magnitude can result so long as the axes of thevibrators are inclined, but not parallel, to one another, and accept-able values of d are then obtained when the angle between them issmall. Born criticises this model on the ground that “ it makesno attempt to reduce a priori the dimensions and location of theassumed resonators to other known properties of the molecule.”The conception of a linear vibrator, also, which implies that theradical to which it corresponds can never be polarised in any directioninclined to its one axis, seems remote from the relatively flexibleelectronic systems which seem to exist in chemical molecules,whilst, in the case of the simplest active molecule with a centralasymmetric carbon atom, the presence of four dissimilar radicalsseems to call for four vibrators, and the system of two anisotropicresonators must form part of a molecule containing at least fouratoms or radicals, since otherwise a plane of symmetry would bepossible.6Kuhn’s model does not therefore appear to be capable of directapplication to the asymmetric carbon atom, but there is a class ofcompound to which it bears a closer resemblance, i.e., those spiro-molecules which, though possessing no asymmetric carbon atom,have no plane of symmetry and can therefore be prepared in3 2.physikal. Chem., 1929, [ B ] , 4, 14; Trans. Paraday SOC., 1930, 26, 293;4 2. physikal. Chern., 1933, [B], 20, 325. See also M. Born, Ann. Physik,2. physikal. Chem., 1933, [B], 22,406.Ber., 1930, 63, 190.1918, [iv], 55, 177.6 M. Born, loc. cit., ref. (1); T. M. Lowry, Nature, 1935, 136, 191122 GENERAL AND PHYSICAL CHEMISTRY.optically active forms. Kuhn and Bein selected as an exampleerythritoldipyruvic acid (I), in which the niolecular dissymmetryarises from the fact that the planes containing the two systemsH0,C-C-CH, must be perpendicular to one another, as is indicatedby the dotted lines. If the two carboxyl groups are identifiedwith the two completely anisotropic resonators of the originalmodel (Fig.3a), this reduces to the form of Fig. 3b, where theresonators are displaced along their respective axes from the centralaxis of the model. Kuhn and Bein predicted that the configurationof Fig. 3b would be lzvorotatory, and they also investigated theabsolute configurations of the cobaltioxalates in a similar way,8but in neither case were their conclusions in agreement with thegeneral principles now developed by Born.FIG. 3.Kuhn achieved more success in the analysis of curves of rotatorydispersion inside an absorption band (the Cotton effect). Experi-ment shows that, as an absorption band is approached, the rotationrises to a maximum value (+ or -), returns to zero at the centre ofthe band, and then passes through a second maximum value ofopposite sign.This phenomenon was successfully treated byL. Natanson9 on the basis of Fresnel?s fundamental postulate ofcircular double refraction in an optically active medium and Cotton’sdemonstration of the corresponding phenomenon of circulardichroism (difference of absorbing power for light circularly polar-ised in left- and right-handed senses). The contribution of theabsorption band to the rotatory dispersion of the molecule (its“ partial rotation ”) can be predicted from a knowledge of the7 2. physikal. Chem., 1934, [B], 24, 335.8 2. anorg. Chem., 1934, 216, 321.9 Bull. Acad. Sci. Krakow, 1908, 7 6 4 ; J . Phys. Radium, 1909, [iv], 8, 321.See also Kuhn and Freudenberg, “ Handbuch der chemischen Physik,” 1932,8, 111, p.77ALLSOPP : PHYSICAL BASIS OF OPTICAL ROTATORY POWER. 123shape of the absorption curve ( L e e , its strength f as determinedfrom the area covered, which is E . & where E is the molecularextinction coefficient a t frequency v), and of the magnitude of itscircular dichroism, E, - E!, for the measurement of which at ultra-violet wave-lengths W. Kuhn and E. Braun10 have developed asimple method.Numerical calculation of partial rotations by Natanson’s methoddemands a knowledge of the relationship between E and v insideeach absorption band in order that the integral r . d v may becorrectly evaluated. Relationships which had been deduced byNatanson on a classical theory of damped oscillations were foundto be inadequate, but Kuhn and lBraun1l obtained more successwith an empirical exponential expression of a type which had beensuggested by J.Bielecki and V. Henri.12 This expression has beenfurther modified by T. M. Lowry and H. Hudson l3 and the partialrotations then deduced give excellent agreement with the curvesobtained experimentally. Striking examples of the applicationof this method of treating the Cotton effect are the analysis byW. Kuhn and H. L. Lehmann l4 of a very curious curve of rotatorydispersion obtained from p-octyl nitrite, and the demonstrationby H. Hudson, M. L. Wolfrom, and T. M. Lowry l5 that the rotatorypower of tetra-acetyl parabinose is contributed entirely by theultra-violet absorption band of the carbonyl radical, whilst thepartial rotations from the asymmetric carbon atoms entirely cancelone another.(ii) S.3’. in contrast to Kuhn, based his analysis on thesimplest chemical model which can show optical activity, anasymmetric carbon atom surrounded by four different radicals.This is a return to Born’s system of four isotropic resonatorsarranged tetrahedrally; but, instead of making use of the resultswhich had already been established, Boys attempted to calculatethe forced vibrations of the resonators directly, expressing theirpolarisabilities in terms of their refractivities instead of taking intoaccount their characteristic frequencies. This method is involved,and the results do not entirely agree with the rigorously establishedformulze of the general theory.They lead to an expression forthe rotatory power of the molecule in terms of the product of therefractivities of the four radicals, and of a complex function of theff10 2. physikal. Chem., 1930, [B], 8, 445. l1 Ibid., p. 281.12 Physikal. Z . , 1913, 14, 516. Phil. Trans., 1933, [A], 232, 131.14 2. Elektrochem., 1931, 37, 549; 2. physikal. Chem., 1932, [B], 18, 32.l5 J., 1933, 1179.16 Proc. Roy. Soc., 1934, [A], 144, 655.W. C. G. Baldwin, M. L. Wolfrom, and T. M. Lowryhave also found optical cancellation in penta-acetyl p-fructose ; J . , 1935, 696124 GENERAL AND PIiYSICAL CHEMISTRY.linear dimensions of the molecule which he deduced approximatelyfrom the “atomic” radii of the radicals, assuming them to beclose-packed spheres. A similar result was obtained, by differentreasoning, by R.de Ma1lemann.l‘ Since the characteristic frequen-cies of the radicals are only involved implicitly in their refractivities[which may be expressed in the form alc/(A2 - A ~ ~ ) , a/, being a constantand hk. the wave-length characteristic of the lcth absorptionfrequency], it follows that the rotatory power and refractive indexshould depend on wave-length in the same way; but this con-clusion must be invalid,l* since in the case of refractive dispersionthe constants ak are always positive, whereas in the case of rotatorydispersion some of them may be negative, and the general theoryrequires that Cak = 0, a result also obtained by Kuhn; andexperiment actually shows that absorption bands which give only atiny contribution to the refractive index often contribute verylargely indeed to the rotatory power of a molecule.At wave-lengths in the visible spectrum, Boys’s formula leads to values forthe specific rotations of simple alcohols and amines which are inexcellent agreement with experiment, but, as is to be expected, itdoes not give satisfactory values for their rotatory dispersions ;nor can it explain the Cotton effect, since the reversal of sign in therefractivity of the chromophoric radical, which is necessary toaccount for the observed reversal of the sign of the rotatory powera t the centre of its absorption band, does not occur.19 On the otherhand, for a given arrangement of the four radicals, Boys’s analysisleads directly to an unambiguous prediction of the sign of therotation, and he specified the absolute configurations of simpleoptically active molecules such as amyl alcohol.(iii) Born 2O has now reshaped his general theory in such it wayas to make it available immediately for chemical purposes.Hestarts from the simple model of the tetrahedral molecule, but, fortechnical reasons, he assumes the four resonators to be slightlyanisotropic on the ground that theory shows that such anisotropywill inevitably occur as LZ result of the coupling forces even if theresonators are initially isotropic. At present, he considers onlythose wave-lengths which are remote from an absorption frequency,since the complex (and often diffuse) band systems of real moleculesare beyond the scope of the method of analysis employed, and anyformulz which represent the variation of rotatory power insideabsorption bands must at best be semi-empirical in character;l7 Compt.rend., 1925, 181, 298; Trans. Faraday Soc., 1930, 26, 281.1* M. Born, loc. cit., ref. (1).Is T. M. Lowry and C. B. Allsopp, Proc. Roy. Soc?, 1934, [A], 146, 317.2o LOG. cit., ref. (1)ALLSOPP : PHYSICAL BASIS OF OPTICAL ROTATORY POWER. 125but with this restriction, he deduces a simple formula for rotatorypower which depends only on the frequencies and strengths of thefour resonators and on their arrangement in space. In general,this formula is only valid when no two of the resonators are equal,but there is a limiting case where it still holds even when two pairsof them are the same, vix., when the faces of the tetrahedron havethe form of congruent triangles (Fig.4a). Still greater simplificationresults when these tlwo pairs are so arranged that the lines joiningthem are perpendicular to one another and to the line joining thecentres of the corresponding edges of the tetrahedron (Fig. 4b).This, of course, is exactly the configuration of the erythritoldipyruvicacid molecule considered by Kuhn, but whereas Kuhn’s treatmentonly involved two of the four radicals (the carboxyl groups),Born’s formula takes account of all four of them. The formuladoes not implicitly include the sign of the rotation for a givenmolecular configuration, but this can be deduced from the generalFIG. 4.A B(a) (b)theory : ‘‘ The rotation of the plane of the polarisation is representedby the same screw motion which makes the two atom pairs coincide,if one pair is moved along the line connecting the centres of thepairs.” The model of Fig.4c is therefore lzevorotatory, althoughthe screw is right-handed, since chemists specify the sign of rotationwhen facing the on-coming light. This conclusion is the oppositeof that reached by Iiuhn for the qiro-acid; the dispersion factorin Born’s formula, however, is identical with that obtained byKuhn. Born’s formula was used to calculate the rotatory power ofdiaminospiroheptane (II),21 in which the dissymmetry arises fromthe spatial arrangement of the hydrogen atoms and amino-groups,which thus correspond with the pairs of resonators AB, AB in themodel.The parameters in the formula (the distances A-B and0-P in Pig. 4c, and the characteristic frequencies of the hydrogen21 Resolved by (Sir) W. J. Pope and S. E. Janson, Chem. and Ind., 1932,51, 316126 GENERAL AND PHYSICAL CHEMISTRY.atom and of the amino-radical) are not known, but appropriateguesses lead t o a value = 30°, which is in good agreementwith experiment.Born has provided chemists with a physical theory of opticalrotatory power which has a sound mathematical basis, and, whensufficient experimental accuracy in the determination of the variousparameters is attainable, will make it possible t o predict the absoluterotatory powers of molecules of known configuration; but theachievement of such accuracy will always be difficult, for Born’sformula involves the eighth power of the molecular dimensions andthe sixth power of the frequency and the square of the strength ofabsorption bands which lie in a region of the spectrum wheremeasurements are by no means simple.For the moment, there-fore, as T. M. Lowry has pointed out,22 the chief importance ofBorn’s work is that it can be applied to the prediction of the relativemagnitudes of the rotatory powers of related compounds, as functionsof three pairs of their fundamental physical constants, when theexperimental errors in the parameters may be of much lessimportance .23C. B. A.8. DIPOLE MOMENTS AND VALENCY ANGLES.In addition to being used in the qualitative determination ofmolecular structures,l dipole moments have been applied for thepurpose of calculating valency angles.The fundamental assump-tions involved are the constancy of bond moments, which aresupposed to act along the direction of the valency bonds, and theirstrict vector additivity without any interaction effects of onemoment on another.2 If the constituent bond moments, eithersingly or in the form of group moments, and the total dipolemoment of a compound are known, then clearly it should, in general,be possible to calculate the angles between certain individualmoments, i.e., between the corresponding covalency linkages.One of the simplest applications is t o determine the angles betweenthe o-, m-, and p-directions, respectively, in the benzene ring; ifthis is a plane regular hexagon, these angles should be 60°, 120°, and180°, respectively.As far as the rn- and p-positions are concerned,22 Nature, 1935, 136, 191.23 Reference must also be made to the appearance of T. M. Lowry’s“ Optical Rotatory Power ” (Longmans, 193!5), which contains a comprehon-sive detailed account of the development and significance of this recent work.(Sir) J. J. Thornson, Phil. Mag., 1923, 46, 513; A., 1923, ii, 682; see also1 Ann. Reports, 1931, 28, 387.I(. Hiijendahl, Phyeikal. Z., 1929, 30, 391; A . , 1929, 980GLASSTONE : DIPOLE MOMENTS AND VALENCY ANGLES. 127the results are in agreement with expectation, but the moments ofo-substituted compounds frequently imply that the angle betweenthe valency directions is greater than 60°.3 This discrepancy,known as the " ortho-effect," has been attributed to actual distortionof the molecule resulting from the size of the substituent groups:or to mutual interaction between the two dipoles,5 so that theassumption of the constancy of the group m.oments-or of theirstrict vector additivity-taken as equal to the values for thecorresponding monosubstituted benzene compounds, is no longervalid.It is probable that both factors are operative : measurementsof the C-I and 1-1 distances in o-di-iodobenzene by the electron-diffraction method indicate that the angle between the two C-Ibonds is at least 68°,6 and may be as high as A similardistortion of the molecule appears to oecur in the peri-substitutednaphthalene There is little doubt, however, that, inaddition, interaction between groups occurs : 9 in some cases this isprobably due to simple inductive polarisation, but in others it isconnected with the permanent electromeric, i.e., mesomeric,10 effectin the molecule.ll It is the error in the calculations resulting fromthe presence of such an effect which led to the conclusion l2 that themoment of the >C-CN system does not act in the directionof the C-C bond; there is now little doubt that this view isinc0rrect.1~In general, when two identical or different groups, or when threeC.P. Smyth and S. 0. Morgan, J . Amer. Chem. Soc., 1927,49,1030; A.,1927, 611 ; E. Bergmann and L. Engel, 8. physikal. Chem., 1930, [B], 8, 111 ;A., 1930, 979; E.Bergmann, L. Engel, and S. Shndor, ibid., 10, 106; A.,1930, 1501.4 C. P. Smyth and S. 0. Morgan, Zoc. cit.,5 H. M. Smallwood and K. F. Herzfeld, J . Amer. Chem. SOC., 1930, 52,6 H. de Laszlo, Trans. Paraday SOC., 1934, 30, 892.7 S. B. Hendricks, L. R. Maxwell, V. L. Mosley, and M. E. Jefferson, J .Chem. Physics, 1933,1, 549; A., 1934, 17.8 A. Weissberger, R. Sangewald, and G. C. Hampson, Trans. ParadaySOC., 1934, 30, 884; A., 1934, 1157.0 G. C. Hampson and L. E. Sutton, Proc. Roy. SOC., 1933, [A], 140, 562;A., 1933, 766; H. Poltz, 0. Steil, and 0. Strasser, 8. physikal. Chem., 1932,[B], 17, 155; A,, 677; E. G. Cowley and J. R. Partington, J . , 1935, 604; A.,809 ; K. Hiijendahl, Zoc. cit.1019; A., 1930, 84.10 C. K. Ingold, J., 1933, 1120; A ., 1933, 1151.11 G. M. Bennett, Ann. Reports, 1929, 26, 132; G. C. Hampson and L. E.Sutton, Zoc. cit.; G. M. Bennett and S. Glasstone, Proc. Roy. SOC., 1934, [A],145, 71 ; A., 1934, 831.12 E. Bergmann and M. Tschudnovski, 8. physilcal. Chem., 1932, [B], 17,116 ; A., 1932, 677.13 A. Weissberger and R. Sangewald, J., 1935, 856; A., 976; cf. alsoR. P. Cook and P. L. Robinson, ibid., p. 1001 ; A., 1064128 GENERAL AND PHYSICAL CHEMISTRY.identical groups, are attached to the same atom, it, is possible todetermine the valency angles, provided the individual groupmoments and the total moment of the compound are a~ai1able.l~For example, the angles between the C-X links in CH2X2 andCHX,, where X is a halogen, have been calculated in this manner ; 14, l5an allowance of 0.4D for the moment of the G H bonds can bemade, or alternatively, it may be assumed that the value for theC-X bond is equal to the moment of CH,X, the neglect of theC-H moment resulting in a cancellation of the errors involved.The angles for methylene chloride and for chloroform were foundto be about 130" and 116", respectively, in good agreement withthose obtained from X-ray diffraction measurements on thevapours,16 vix., 124" & 6" and 116" & 3".Analogous observationsof electron scattering show, however, that the latter valuesare probably in error,17 and that the valency angles in the twocompounds mentioned are 111" & 2", a result in agreement withcalculations based on wave mechanics.18 It is evident that in thechloromethanes there is considerable mutual interaction of thedipoles so that the C-C1 bond moments may be reduced by as muchas 30Y0.l9 Similar interaction probably occurs in the otherhalogenomethanes ; no measurements of interatomic distances inthe vapours, from which valency angles can be calculated, havebeen reported, but it is probable that, as the size of the halogenincreases,20 the valency angles become greater than the tetrahedralvalue, although it is unlikely they will prove to be as large as those-134" and 140" for methylene bromide and iodide, respectively-calculated from dipole moments.14 I n spite of statements to thecontrary, it now appears that inductive effects are also operativein cis-dichloroethylene : the presence of a double bond in thismolecule may, however, be a special contributive factor.21When one or more phenyl groups are attached to a central atom,valency angles may be calculated by making use of the fact that inl4 G.C. Hampson and L. E. Sutton, Zoc. cit., ref. (9).I s E. Bergmann, L. Engel, and S. S&ndor, Zoc. cit., ref. (3); E. Bergmann,L. Engel, and H. A. Wolff, 2. physikal. Chena., 1932, [B], 17, 81; A., 1932,677; see also F. R. GOSS, J., 1934, 1467; A., 1934, 696.16 L. Bewilogua, Physikal. Z., 1931, 32, 265; A,, 1931, 788.1' R. Wierl, Ann. Physik, 1931, 8, 521 ; A., 1931, 665; L. E. Sutton andl8 W. G. Penney, Trans. Faraday SOC., 1935,31, 734; A., 810.20 Cf. C. P. Smyth and H. E. Rogers, J . Amer. Chem. SOC., 1930, 50, 222;A., 1930, 1093.21 G.C. Hampson and L. E. Sutton, Zoc. cit., ref. (9), p. 565; see alsoE. C. E. Hunter and J. R. Partington, J., 1931, 2062; 1932, 2819; A., 1931,1113; 1932, 210.L. 0. Brockway, J. Amer. Chem. SOC., 1935, 57, 473.L. E. Sutton and L. 0. Brockway, loc. citGLASSTONE : DIPOLE MOMENTS AND VBLENCY ANGLES. 129the p-position to the point of attachment the moment of a groupsuch as a halogen, CN, NC, CH,, or NO, acts along the axis of thebenzene ring. The dipole moment p of a compound c6H5-A/Bis determined by the bond moments of C6H5-A (pl) and of A-B(p2), and by the valency angle (e), which are related by the usualequation p2 = p12 + p z + 2p1v2 00s 8, the correct signs being usedfor the directions of the individual moments.2 Another equationconnecting pl, p2, and 8 can be obtained from the measured momentof the compound p-X*C,H,*AB, the X-C,H, bond moment,assumed equal to the moment of the compound C6H5X, acting inthe line of the C,H4-A bond.In order to calculate 8 , it is necessaryto know the value of the bond moments pl and p2, or to be able toexpress pl as a function of p2; for practical purposes the lattercondition is best satisfied by making pl and p2 equal, i.e., B is also aphenyl group, and the compounds examined are diphenyl deriv-atives, C,H5eA*C,H,. By using either the moment of a mono-substituted compound, vix., p-X*C,H,*A*C,H,, or that of a pp’-disubstituted derivative, vix., pp’-X*C6H4*A*C6H4*X, independentvalues of the valency angle can be obtained; in the latter case,however, two solutions are possible, so that the result is not entirelyfree from uncertainty.Several fundamental assumptions are involved in these calcul-ations : (a) that the dipole moment of a compound is strictly thevector sum of the constituent bond or group moments, (b) thatthe valency angle of A remains unchanged by the introduction of thesubstituent X in the p-position of the phenyl group, and (c) thatthere is no interaction between X and the group AB, e.g., A*C6H5.The first assumption is implicit in all calculations involving bondmoments, and the second is reasona,bly probable, except in so faras substitution in two benzene nuclei may result in some repulsion,22but the third assumption requires further consideration.A testfor interaction between groups is to calculate from the moments ofC6H5*AeB, c6H5x, and p-X*C,H,*A*B, by means of a simple vectortriangle, or the equivalent equation, the so-called “ characteristicangle,” 4,23 between the resultani; moment of C,H,*A*B and theaxis of the benzene ring passing through A; for a series of sub-stituents X, the value of + should remain unchanged. It was atone time claimed that 4 was in fact constant for a number of sub-stituted anisoles and anilines,14, 22 except when the moleculecontained groups having large and opposed electromeric effects.29 E. Bergmann and $I. Tschudnovski, 2. phpilcal. Chem., 1932, [B], 1’7,107; A . , 1932, 677.2s E. Bergmann, L. Engel, and S. Shdor, ibid., 1930, [B], 10, 397; A.,1931,23.REP.-VOL.XXXII. 130 GENERAL AND PHYSICAL CHEMISTRY.As far as the anisoles are concerned, the apparent constancy of 4was shown to be due to the use of incorrect dipole moments; theactual values of the angle for different p-substituents follow thepolar sequence CR,, F, C1, Br, I, and NO,, and a similar variationprobably occurs with the corresponding p-substituted anilines.There is little doubt that interaction occurs between the groupsX and OCH, in the anisoles; this does not appear to be due toinductive effects, but to a permanent polarisation of the mesomerictype transmitted through the conjugated system of single anddouble bonds in the benzene ring.24 The same type of interactionappears to occur in all compounds in which a phenyl group isattached to oxygen, sulphur, or nitrogen.For the phenols, thevalue of +, with X = CH,, C1, or Br, appears to be constant,25 andhence it has been claimed that there is here no evidence for inter-action;26 in view of the fact that p-chloro- and p-bromo-phenolare virtually one case, and of the very small difference between themoments of phenol (166D) and p-cresol (1.57D), which leads toconsiderable uncertainty in the calculation of +, the evidence forthe constancy of this angle is very slight.The methods described above for determining valency angles indiphenyl derivatives have been used to calculate the oxygen andthe sulphur angle in diphenyl ethers and diphenyl sulphides,14~ 223 23,27but in view of the existence of interaction moments of considerable,although unknown, magnitude, the results are of no direct value.249 26An examination of the errors in the calculated angles, as a con-sequence of this interaction moment, supposed to act along the axisof the benzene ring passing through the p-positions occupied by Aand the substituent X, shows 28 that in certain cases, e.g., nitro- andbromo-diphenyl ethers, the errors in the two independent values of8 obtained from mono- and di-substituted compounds are ofopposite sign; i.e., one is greater and the other less than the truevalue.With other compounds, e.g., ditolyl ethers, the errors areboth in the same direction. If these limitations are borne in mind,and allowance is made for possible errors in observation and for24 G.M. Bennett, Trans. Paraday SOC., 1934, 30, 853; A., 1934, 1157;G. M. Bennett and S. Glasstone, Zoc. cit., ref. (11).25 H. L. Donle and K. A. Gehrckens, 2. physlsikd. Chern., 1932, [B], 18,316; A., 1932, 984.26 L. E. Sutton and G. C. Hampson, Trans. Paraday SOC., 1935, 31, 945;A , , 1056.27 C. P. Smyth and W. S . Walls, J . Amer. Chern. SOC., 1932, 54, 3230; A.,1932, 984; G. C. Hampson, R. H. Farmer, and L. E. Sutton, Proc. Roy. SOC.,1933, [ A ] , 143, 147; A., 1934, 131.2 8 G. C. Hampson, Trans. Paraday SOC., 1934, 30, 858; G. C. Rampsonet al., Eoc. c i t . ; L. E. Sutton and G. C. Hampson, Zoc. cit., refs. (9) and (26)GLASSTONE : DIPOLE MOMENTS AND VALENCY ANGLES. 131solvent effects, for atom polarisation, and for the fact that theinteraction moment operative along each benzene ring axis in adisubstituted ether may be less than the value for a mono-sub-stituted derivative, an examination of the available data for varioussubstituted diphenyl ethers leads to the conclusion that in thesecompounds the oxygen valency angle 26 is 128" & 4". This resultis in harmony with the fact that diphenylene dioxide has zeromoment, so that the molecule must be planar, and consequentlythe minimum oxygen valency angle in compounds of this typemust be 120"; 29 it also agrees with the calculations of deviationmoments, which necessitate a valency angle greater than the tetra-hedral value in diphenyl ethers, in order to yield a consistent set ofres~lts.~O It is of interest to note that the new calculations implyan interaction moment of about 0.7D for the nitro-group, 0.25D forbromine, and 0.1D for the methyl group, acting along the axis ofthe benzene ring, in substituted diphenyl ethers.Electron-diffractionmeasurements indicate an angle of 118" -+ 3" in pp'-di-iododiphenylether.31The data for diphenyl sulphides are not so extensive as for theethers, but the application of the limitations mentioned above tothe available measurements leads to a value 26 of 113" & 3" for thesulphur valency angle. The appreciable dipole moment of thi-anthren, about l6D, indicates that in this compound the valencyangle of the sulphur atom must be less than 120" ; 32 using the momentfor the C6H5-S bond, estimated from measurements on diphenylsulphide, the actual angle may be calculated to be about l10".33An angle of 110-120" is of the order proposed for the sulphur atomin the thiocyanate group34 and in alkyl sulphides35 to account forthe dipole moments of various compounds.It is perhaps surprising that the oxygen angle in the diphenylethers is markedly greater than the corresponding angle in otheroxygen compounds ; for instance, in water the value as determined59 G.M. Bennett, D. P. Earp, and S. Glasstone, J., 1934, 1179; A., 1934,1058.30 G. 31. Bennett and S. Glasstone, Zoc. cit., ref. (ll), p. 76.31 L. R. Maxwell, S. B. Hendricks, and V. M. Mosley, J . Chem. Physics,1935, 3, 699.32 E. Bergmann and M. Tschudnovski, Ber., 1932, 65,457; A,, 1932, 507;W. S. Walls and C.P. Smyth, J. Chem. Physics, 1933, 1, 337; A., 1934, 12;G. M. Bennett and S. Glasstone, J . , 1934, 128; A., 1934, 349.33 L. E. Sutton and G. C. Hampson, Zoc. cit., ref. (26), p. 951; cf. alsoG. M. Bennett, Zoc. cit., ref. (24), p. 858.34 E. C. E. Hunter and J. R. Partington, J., 1932, 2825; A., 1933,210.35 K. A. JenRen, 2. anorg. Chem., 1935, 225, 97; see, however, E. C. E.Hunter and J. R. Partingtan, J., 1932,3812; A., 1933,210132 GENERAL AND PHYSICAL CHEMISTRY.from spectroscopic measurements 36 is about 105", and in dimethylether the angle has been calculated as 118" from the Ramanspectrum 37 and as 111" & 4" from electron-diffraction measure-ment~.~8 By assuming the moment of the G O link to be the samein dimethyl ether as in ethylene oxide, in which the oxygen angle isdetermined by the known dimensions of the oxygen and the carbonatom, the angle in the ether has been calculated 39 to be 116" -+ 7";the objection that the inductive effect of one (3-0 bond on the othermay be different in the two compounds considered 40 does not appearto apply.The angle of 110" in dimethyl ether deduced by the" shadow area " method 41 should not be quoted as evidence, sincean application of the same principle led to the conclusion that theKaufler formula was applicable to diphenyl.42 The natural valencyangle of oxygen in water and in the simple ethers, and also inchlorine monoxide and oxygen fluorideF89 43 appears to be slightlyless than the tetrahedral value, whereas in diphenyl ethers andrelated compounds it is 120" or greater ; unless the result is due toa misinterpretation of the dipole moments, which appears improbable,8ome reason for this discrepancy must be sought.The importantsuggestion has been made 26 that in diphenyl ether8 resonance occursbetween the normal molecule (I) and two possible excited states (11) :(1.)The observations(If.)of Pauling and his co-workers44 indicate as anempirical fact that, when- resonance occurs between differentpossible structures of a molecule, the actual dimensions within themolecule approach more closely the values for the form having thegreater radial force constants ; i.e., the molecular configuration willfavour distances and angles required by double bonds over those36 R.Mecke, 2. Physik, 1933,81,313; A., 1933,445; see also E. F. Barkerand W. W. Sleator, J . Chem. Physics, 1935,3,660.3 7 N. G. Pai, Indian J . Physics, 1934, 9, 121; A., 1935, 283.3 8 L. E. Sutton and L. 0. Brockway, Zoc. cit., ref. (17).30 G. M. Bennett, Zoc. cit., ref. (24); see also N. G. Pai, Zoc. cit., ref. (37).40 L. E. Sutton and G. C. Hampson, Zoc. cit., ref. (26), p. 953.4 1 W.A.Hare andE.Mack, J . Amer. Chern.Soc., 1932,54,4272; A,, 1933,ll.42 E. Mack, ibid., 1925, 47, 2468; A., 1925, 1124.43 H. Boersch, Monatsh., 1935, 65, 311; A., 687; see also J. S. Allen andH. Hibbert, J . Amer. Chem. Soc., 1934,56, 1398; A., 1934, 831; M. M. Otto,ibid., 1935, 57, 693; A., 1192; C. R. Bailey and A. B. D. Cassie, Proc. Roy.SOC., 1933, [A], 142, 129; A., 1933, 1228.44 E.g., L.Pauling, Proc. Nut. Acad. Sci., 1932,18, 293; also L. E. Sutton,Trans. Faraday SOC., 1934,30,789; A., 1934, 1156GLASSTONE : DIPOLE MOMENTS AND VALENCY ANGLES. 133necessitated by single linkages. In the diphenyl ethers, therefore,resonance between (I) and either form of (11) will result in a tendencytowards an oxygen valency angle of 125" 16', the usual value betweena single and a double bond attached to a tetrahedral atom, insteadof the normal angle between two single linkages. The same factorshould be operative, to some extent, in phenols and phenolic ethers.If the two benzene rings in diphenyl ether are to lie in one plane, itwould be necessary for the oxygen valency angle to be widened toa value lying between 123" and 145", according as an allowance of0-0.5 8.was made for an envelope 45 around the hydrogen atomsin the o-positions to represent the repulsion of the electrons. Thepossibility of this factor influencing the measured value of thevalency angle has been ~onsidered,~~ and there is reason to believethat the resonance mentioned above may favour a configurationin which the two benzene rings are coplanar.The normal valency angle of sulphur appears to be definitely lessthan that of oxygen; analysis of the Raman and infra-red spectraof hydrogen sulphide leads to an angle of 90" 47 or 92" 20',48 and avalue of 100" has been proposed for dimethyl sulphide, based onits Raman spectrum.37 The angle of 113" & 3" for diphenylsulphide, obtained from measurements of dipole moments,26 maytherefore indicate resonance of a similar type to that postulated forthe diphenyl ethers.Nothing is known of the value to be expectedfor the angle between a single and a double bond attached tosulphur,48a but owing to the fact that the radius of the sulphuratom is greater than that of oxygen, a smaller valency angle wouldaccommodate two benzene rings in one plane.The principles used for calculating valency angles in compoundsof the type C6H5*A*C,H5 can also be applied in cases where otheratoms or groups are attached to the atom A, provided the momentof the compound still lies along the axis of symmetry of the mole-cule, e.g., diphen~lrnethane,4~ benzophenone ,50 diphenylsulphone,6145 N.V. Sidgwick, Ann. Reports, 1932,29, 70.46 Idem, ibid., p. 72; C. P. Smyth and TV. S. Walls, ref. (27), p. 3238.47 A. Dadieu and K. W. F. Kohlrausch, Physikal. Z., 1932, 33, 165; A.,1932, 320.P. C. Cross, Physical Rev., 1935, 47, 7.4 ~ 3 ~ See, however, P. C. Cross and L. 0. Brockway, J . Chem. Physics,1935, 3, 821.49 E. Bergmann, L. Engel, and H. A. WOW, loc. cit., ref. (15); G. C.Hampson, R. H. Farmer, and L. E. Sutton, loc. cit., ref. (27).50 E. Bergmann, L. Engel, and H. Meyer, Ber., 1932, 65, 446; A., 1938,506; L. E. Sutton and G. C. Hampson, Zoc. cit., ref. (26), p. 955; see also 0.Fuchs and H. L. Donle, 2. phyeikal. Chem., 1933, [B], 22, 1; A., 1933, 888;0. Hessel and E. Nseshagen, ibid., 1929, [B], 4, 217; A., 1929, 275.61 E. Bergmann and M. Tschudnovski, ZOC. cit., ref. (32)134 GENERAL AND PHYSICAL CHEMISTRY.aa-diphenylethylene derivative^,^^ and aayy-tetra~hsnylallene.~~In diphenylmethane and diphenylsulphone there is no possibilityof resonance, so that the angle between the phenyl groups is closeto the tetrahedral value, any small deviations being attributableeither to experimental error, to the influence of mutual induction onthe bond moments, or to steric effects; with benzophenone andaa-diphenylethylene the corresponding angles are about 130°, andin both cases resonance, which should result in the angle beinggreater than the tetrahedral value, is theoretically possible. Inthe aa-diphenylallene compounds the angle between the valenciesjoining the phenyl groups to the carbon atom is found to be 119";this increase over the tetrahedral angle is in conformity with theThorpe-Ingold valency-deflexion hypothesis, but it might also beaccounted for by resonance.A similar method to that adopted for diphenyl compounds can beapplied to triphenyl derivatives l4 in which the resultant momentof the molecule acts along its axis of symmetry; for triphenyl-methane and triphenylchloromethane the angle between the threephenyl groups has been calculated from dipole-moment data 54 tobe, as expected, about 110". The method is, theoretically, availablefor triphenylamine, but the requisite measurements have not yetbeen made. The application of a similar principle to the determin-ation of the nitrogen valency angle in triethanolamine appearsto be open to criticism, since no allowance has been made in thecalculations for the possibility of free rotation about the N-C andC-0 linkages.When the direction of the moment of an unsubstituted diphenylcompound is not collinear with the bisector of the angle betweenthe axes of the benzene rings, but is equally inclined to both of them,as in diphenylsulphoxide or diphenylamine, it is possible to calculatethe angle between the phenyl groups from a knowledge of themoments of the unsubstituted molecule and of a mono-p-substitutedand a di-pp'-substituted derivative containing the same sub-stituent.14 An alternative value of the angle can be obtained if,instead of the last two moments, the values are known for twodi-pp'-compounds, each with two identical groups, which are aswidely different as possible in the two compounds. Both thesemethods have been used to determine the configuration of diphenyl-s~lphoxide,~~ with the result that the angle between the two52 E. Bergmann, L. Engel, and H. Meyer, Zoc. cit., ref. (50).53 E. Bergmann and G. C. Hampson, J . , 1935,989; A., 1115.(i4 E. Bergmann, L. Engel, and H. A. Wolff, Zoc. cit., ref. (15).55 J. N. Pearce and L. F. Berhenke, J . Physical Chem., 1935, 39, 1005.56 G. C. Hampson, R. H. Farmer, mdL. E. Sutton, Zoc. cit., ref. (27), p. 164GLASSTONE : DIPOLE MOMENTS AND VALENCY ANGLES. 135C,H,-S bonds has been found to be 112" & 8" ; the close agreementbetween this and the tetrahedral angle is in harmony with the factthat from the chemical properties of the sulphoxide group there isno expectation of resonance of the type to which the widening ofthe valency angle in diphenyl ether has been attributed.26The alternative procedure for determining the valency angle in acompound of the type C6H5-A--B, involving a knowledge of oneof the group moments (p. 129), has been applied to compoundshaving the general formula C,H,*CH,X, wix. , benzyl chloride,bromide, and cyanide. In these substances no appreciable inter-action between the CH2X group and other groups substituted inthe p-position is to be expected, and so the dipole-moment methodshould give reliable results. The assumption is made that theresultant moment of the unsubstituted compound, C,H,*CH,X,acts in the direction of the C-X bond; this is equivalent toassuming that the bond moments of C H , in the methylene group,and of C,H,-C are zero, so that the only effectivemoment in themolecule is that of the C-X linkage, the value of which is equalt o the measured dipole moment of the compound. These postulatesare not strictly justifiable, but it is probable that the errors involvedeffectively cancel one another. From the moments of the benzylcompounds and of a number of p-substituted derivatives, the anglebetween the C,H,-C and C-X bonds was calculated as 114-119" :the departure from the tetrahedral angle is regarded as being nomore than the probable errors involved in the determination.57In the benzyl compounds no resonance, of the kind already con-sidered, is to be anticipated, so that there should be no widening ofthe valency angle.58Attempts have been made to estimate the oxygen angle in anisoleon the assumption that the moment of the O-CH, bond is the sameas in dimethyl ether; 59 the values of 140-150" obtained in thismanner are undoubtedly in error, because of group-interactioneffects in the p-substituted anisoles, the moments of which arerequired for calculating the valency angle.25, 6o A similar difficultyarises in connexion with the oxygen angle in phenol itself and inother phenolic ethers, but no dipole method appears available atpresent for overcoming it.57 C. P. Smyth and W. S . Walls, J . Amer. Chern. SOC., 1932, 54, 1854; R.,1932, 794.58 See, however, J. M. A. de Bruyne, R. M. Davis, and P. M. Gross, ibid.,1933,55, 3936 ; A., 1933, 1230.59 G. C. Hampson et al., Zoc. cit., ref. (27); see also C. P. Smyth and W. S.Walls, Zoc. cit., ref. (27), p. 3237.80 G. M. Bennett and S. Glesstone, Zoc. cat., ref. (11); L. E. Sutton and GI. C.Hampson, loc. cit., ref. (26)136 GENERAL AND PHYSICAL CHEMISTRY.The dipole moment of 2-13D for hydrogen peroxide was a t firstattributed 61 to its having the structure :>O+O, but it wasshown later that the result was in harmony with the ordinaryformula H*O*O*H, on the assumption that the oxygen valencyangle is tetrahedral and that there is free rotation of the OH groupsabout the 0-0 axis. From considerations of wave rnechanic~,~~however, it appears that free rotation is unlikely, although spectro-scopic considerations indicate the formula HOOH to be the correctone. It is concluded that the two OH groups, which are stationary,are not coplanar, and that the two H.0-0 planes in the moleculeare inclined at an angle of about 100" to one another. The calcul-ations indicate that the oxygen valency angle is also about loo",and these two values lead to a dipole moment of %OD, comparedwith the observed 2*13D, based on the assumption that the 0-Hbond moment is the same as in water, and that in the latter substancethe oxygen angle 3G is 105". Similar application of wave-mechanicalmethods 63 to the hydrazine molecule indicates that it has a structureanalogous to that of hydrogen peroxide ; the nitrogen valencyangle is about 110", and the two planes containing nitrogen atomsand bisecting one of the two N<H angles are perpendicular toone another. Prom the known dipole moment of ammonia and thedimensions of the molecule,G4 the moment of the N-H link isfound to be 1-3D, and the value being assumed to be the same inhydrazine, the moment of the latter is calculated as 1.70D, on thebasis of the co&guration suggested; this result is in satisfactoryagreement with the observed value 1.83D.Some confirmation of the stereochemistry of certain elements inthe second and third groups of the periodic classification has beenobtained from dipole-moment data. The moment of boron tri-chloride is zero in solvents with which it does not combine,65 andhence this compound probably has a symmetrical planar structure,the valency angle being 120". This conclusion is in agreement withthat reached from a study of the diffraction of electrons by borontrichloride.66 Aluminium bromide has a very small dipole momentH61 E. P. Linton and 0. Maass, Canadian J . Res., 1932, '9, 81 ; A., 1933, 8.c2 W. Theilacker, 2. physikal. Chem., 1933, [B], 20, 142; A., 1933, 338;see also E. C. E. Hunter and J. R. Partington, J., 1932, 2817; 'A., 1933, 210.W. G. Penney and G. B. B. M. Sutherland, Trans. Farachy SOC., 1934,30, 898; J . Chem. Physics, 1934, 2,492; A., 1934, 1158.64 D. M. Dennison and G. E. Uhlenbeck, Physical Rev., 1932, [ii], 41, 313;A., 1932, 982.6 5 H. Ulich and W. Nespital, Z. EleEtrochem., 1931,37,559 ; A., 1931,1213.66 R. Wierl, Zoc. cit., ref. (17)GLASSTONE : DIPOLE MOMENTS AND VALENCY ANGLES. 137in carbon disulphide solution,65, 67 but as it consists largely ofdouble molecules in this solvent,68 its structure is probablyrepresented by Br \ /A], rBr\ fX1\Br /Br although there is no means ofBr Brdeciding between planar and tetrahedral configurations. Themoments of beryllium chloride and bromide in benzene 65 are statedto be zero : if this is so, then in the bicovalent state the molecules arelinear. From observations with diethylmercury and diphenylmer-cury,09 it appears that these substances have small but probablydefinite moments ; it is suggested that the compounds have a linearstructure, but that flexibility of the bonds leads to the setting up ofa resultant moment. Some confirmation of this view is said to beobtained from the molecular dimensions of dibromodiphenylmercury,calculated from electron-diffraction measurements ; 70 the resultsare believed to be compatible with a swing of 30" of the -C,H,Brgroups on either side of a straight line through the mercury atom.The whole subject appears t o be worthy of further investigation.S. G.C. B. ALLSOP.S. GLASSTONE.E. B. MAXTED.E. A. MOELWYN-HUGHES.G. B. B. M. SUTHERLAND.67 W. Nespital, 2. physikal. Chem., 1932, [B], 16, 153; A., 1932, 447.68 H. Ulich, ibid., Bodenstein Festband, 1931, 423; A., 1931, 1229.60 E. Bergmann and W. Schutz, ibid., 1932, [B], 19, 401; A., 1933, 210;G. C. Hampson, Trans. E'araday SOC., 1934, 30, 877; A., 1934, 1157; W. J.Curran and H. H. Wenzke, J. Amer. Chew&. SOC., 1935, 57, 2162.'O H. de Laszlo, Trans. Faraday SOC., 1934, 30, 884.E

ISSN:0365-6217    

DOI:10.1039/AR9353200039

出版商:RSC    

年代:1935

数据来源: RSC

摘要:

INOR8GANIC CHEMISTRY.1. THE PERIODIC TABLE.IN the Mendelkef Centenary Lecture delivered before the ChemicalSociety by Lord Rutherford a striking tribute was paid to thogenius of Dimitri Ivanovitch Mendeldef, who was born on February7th, 1534. It was very fitting that the lecturer himself should havebeen intimately associated with those outst anding developmentswhich have given a new meaning to Mendeldef’s famous law of theelements.Since the Periodic Law was first enunciated, the periodicity ofthe elements has been fully confirmed, and although new discoverieshave from time to time demanded modification of the originalstatement of the law, yet the fundamental ideas still remainessentially as Mendeleef set them forth. It is well known thatinterest in MendelBef’s generalisation was not fully aroused untilthe discovery of gallium in 1875 and scandium in 1579.The factthat these elements possessed the properties predicted by Mendelhffor eka-aluminium and elra-boron was very impressive, and furtherdiscoveries of new elements made it clearer still that the PeriodicLaw was a fundamental truth. Some twelve years ago six elementsout of the possible ninety-two in the Periodic Table were stillunknown. Bohr’s theory of atomic structure led in 1923 t o theisolation from zirconium minerals of element 72, which was namedhafnium, after Hafnia, the ancient name of Copenhagen.2 I n1925 the elements 43 and 75 were found and named masurium andrhenium re~pectively,~ and in 1926 the discovery of the rare earth61 was announced.4 The last of the missing elements, 85 and 87,provisionally called eka-iodine and eka-czesium, were stated tohave been detected in 1931-32. Three years ago, therefore, itseemed that the phase of chemistry dealing with.the discoveryof new elements had come to an end. It cannot be said, bowever,that in every case these more recent discoveries have met withgeneral acceptance. I n particular, a number of writers havequestioned the significance of the evidence upon which the existenceof elements 61, 85, and 87 is based. In this Report an attemptis made to state the evidence for and against these discoveries SOAnn. Reports, 1923, 20, 45. J., 1934, 635; A., 1934, 713.Ibid., 1925, 22, 63. Ibid., 1926, 23, 61. ti Ibid., 1932, 29, 300CARTER AND WARDLAW : THE PERIODIC TABLE.139that the reader may judge whether criticism is justified or not.Reference is also made in the following pages to elements 43 and91, and some recent work on elements of atomic number higherthan 92 is discussed.Since the time of Moseley’s work, which showed dehitely thatan element should exist between neodymium (at. no. 60) andsamarium (at. no. 62), numerous papers have been published dealingwith element 61. In 1917 J. M. Eder deduced from an examinationof the arc spectrum of samarium that his material might containtraces of a new element, but when W. Prandtl and A. Grimm 7 in1924 carried out an exhaustive fractionation of the cerium earthsthey failed to obtain any indication of an element 61.Two yearslater, however, the search for the iiew element appeared to havemet with success, for J. A. Harris, L. P. Yntema, and B. S. Hopkiiisannounced that they had found weak optical absorption bandsfrom a material obtained by the fractionation of large quantitiesof neodymium and samarium salts, and that these bands must beattributed to element 61. Further, they stated that they hadobtained in the X-ray emission spectrum of their preparation aweak but perceptible line which they claimed was the La line ofelement 61. The mean value for this line agreed within 0-0004 8.with the value calculated from Siegbahn’s precision values, althoughthe differences ranged from + 0.0026 to - 0.0047 A. It was held,therefore, that element 61 had been discovered, and the name“illinium ” was proposed for it.Shortly afterwards, L. Rollaand L. Fernandes claimed priority of discovery, as they maintainedthat they had observed the absorption bands, ascribed to element61, before Hopkins and his collaborators. R. J. Meyer lo and R.Glocker l1 and their respective co-workers also believed that theyhad detected element 61 in the difficultly soluble bromate fractionsof rare earths, and proved its presence by three lines in the Kseries of X-ray lines. At this period one gains the impression thatseveral groups of investigators had simultaneously discovered themissing element. J. M. Cork, C. James, and H. C. FoggX2 evenstated that they had produced a sample of material containing1% of the new element which gave seven lines of the L series ofillinium.These findings, however, did not pass without criticism,6 Sitzungsber. Akad. Wiss. Wien, 1917, IIa, 125; A., 1917, ii, 185.7 2. Ccn.org. Chem., 1924,138, 283; A., 1924, ii, 615.8 J . Amer. Chem. SOC., 1926, 48, 1585, 1594; A., 1926, 810, 780.Q Gazzetta, 1926, 58, 435; A., 1926,1083; Atti R. Acmd. Lincei, 1926, [vi],10 R. J. Meyer, G. Schumacher, and A. Kotowski, Naturwiss., 1926,14, 771.11 U. Dehlinger, R. Glocker, and E. Kaupp, ibid., p. 772,12 Proc. Nat. Acad. Sci., 1926, 12, 696; A., 1927, 190.4,498; A., 1927, 190140 INORGANIC CHEMTSTRY.Especially noteworthy is a paper by W. Prandtl l3 in which adetailed examination i8 made of the evidence upon which Hopkinsand his co-workers based their discovery of element 61.Prandtlshows that the absorption bands mentioned by Hopkins as occurr-ing with neodymium salts in dilute solutions were intensified whena small quantity of neodymium nitrate was added to a large amountof samarium nitrate. Consequently, these bands did not arise froma new element lying between neodymium and samarium. More-over, he maintained that the X-ray investigation of the rare-earthmixture was carried out in an apparatus unsuitable for the purpose,and that the so-called La, and Lpl lines of element 61 were reallydue to small amounts of platinum, barium, and bromine. It isinteresting that later investigators have failed to obtain any evidencefor element 61. In 1931 S. Takvorian14 reported that no linesattributable to element 61 could be observed from an examinationof the rare earths from Indian monazite.(Frau) I. Noddack in1934 in an important communication l5 recorded the results of anextensive investigation a t the Phy si kalis c h Te chnischen- Reichs -anstalt on the problem of element 61. At the request of variousworkers, over a period of eight years, she and W. Noddack haveexamined fifteen preparations by X-ray spectroscopy for thepresence of element 61. I n none of these preparations was anytrace of this element found. Further, 100 kg. of rare earths fromvarious sources were worked up for fractions between neodymiumand samarium without giving any indication of the required element.Again, an investigation by X-ray methods of the rare-earth fractionsfrom the Auergesellschaft which had been obtained from very largequantities of monazite did not afford, after very exhaustive fraction-ation, any evidence of element 61.(Frau) I. Noddack expressesthe opinion that, i f one surveys the negative results from so manyinvestigations, one must conclude that there is not sufficient evidencein the literature since 1926 to say that this element has been dis-covered, and it must be admitted that this conclusion is a reasonableone.Apart, however, from the controversial question whether element61 has ever been detected, it is interesting to speculate why thiselement does not occur in quantity in rare-earth mixtures. (Frau) I.Noddack suggests that its absence may be due to its instability.Samarium (at.no. 62) is radioactive, according t o G. von Hevesy 1613 I;. angew. Chem., 1926, 39, 897; W. Prandtl and A. Grimm, ibdd., p.14 Cornpt. rend., 1931, lga, 1320; A,, 1931, 783.l5 2. angew. Chem., 1934, 47, 301; A., 1934, 853.16 G. von Hevesy and M. Pahl, Nature, 1932,130,846; A., 1933,4.1333; A., 1927, 9CAltTER AND WARDLAW THE PESIODIC TABLE. 141and others, and loses an a-particle. May it not be that element 61also is radioactive, losing a p-particle, whereby its concentrationin the lithosphere may become so small that it would no longer bedetectable by the methods so far employed? Or again, may notelement 61 have a marked tendency to exhibit bivalency, for bothsamarium (at. no. 62) and europium (at. no. 63) are bivalent insome of their compounds? To test this theory (Frau) I.Noddackhas explored the possibility that element 61 may be presentin minerals containing the alkaline earths, but so far, withoutsuccess.In the search for element 85, the idea that it may result from aradioactive decomposition has not been overlooked. It is obviousthat it may be produced by the loss of two a-particles from actinium(at. no. 89) or by the expulsion of a p-particle from polonium (at.no. 84), and with these ideas in mind G. von Hevesy and R. Hobbie 1'have worked up a kilogram of Katanga pitchblende. The combinedprocess of concentration and examination by X-ray spectroscopymakes it possible to detect less than leg g. of the element, but eventhis could not be found. It will be mentioned later that F.Allisonand his colleagues claim to have found elements 85 and 87.Numerous attempts have been made to discover the elusiveelement 87, and a wide range of methods has been employed inthe search. P. R. Gennet6 l8 has prepared an excellent summaryof the results obtained up to 1933. The positive results are fewand include the observations made by 5. Papish and E. Wainer l9in 1931. It will be recalled that these investigators preparedfrom 10 kg. of samarskite, rich in uranium, a caesium preparationwhich they stated showed the X-ray lines of element 87. Theyheated the mineral to 1000" in a stream of hydrogen chloride,collected the sublimate, and converted it into sulphates, whichwere purified and fractionally crystallised as alums.The leastsbluble fractions were examined in a Siegbahn apparatus of highdispersion. As an example of the results obtained, the Lal linefor element 87 calculated to be 0.8524 was found as 0.853 A. L. L.Barnes and R. C. Gibbs 2o then examined by positive-ray methodsa cssium alum prepared from the samarskite used by Papish andWainer. They obtained a result which confirmed the existence ofelement 87, but the iEtensity of the important lines was very feeble.So far, no other investigator has been able to obtain similar results.(Frau) I. and W. Noddack,15 using various czsium-containing17 2. anorg. Chem., 1932, 208, 107; A., 1932, 1073.18 Bull. SOC. chim., 1933, [ivj, 53, 140.19 J . Amer. C h m . SOC., 1931, 53, 3818; A., 1931, 1348.20 Phguicd Rev., 1932, [El, 40, 318; A*, 1933, 1223142 INORGANIC CHEMISTRY.minerals, have failed to isolate any preparation that gives theX-ray lines required for element 87, and K.T. BainbridgeFl employ-ing a Dempster spectrograph, has examined czesium chloride, madefrom pollucite and from lepidolite mica, with negative results.Element 87 has also been looked for as a secondary product fromthe disintegration of radioactive substances, but again withoutsuccess. Theoretically, it may arise from element 89 (meso-thorium-11) by loss of an a-particle, or from element 86 (radon)by emission of a p-ray. Experiments by G. von Hevesy22 and 0.Hahn and 0. Erbacher33 to test these possibilities have yieldednegative results. The only other positive result comes from theuse of a magneto-optic method, which is based on the researchesof 3.W. Beams and F. Allison on the Faraday effect.24 This effectis the well-known phenomenon that the plane of polarisation oflight is rotated by a liquid when this is placed in a magnetic field.It has generally been assumed that the Faraday effect does notlag behind the application of the magnetic field. J. W. Beamsand I?. Allison maintain, on the contrary, that there is a retardation,and their conclusions are based on this assumption. They haveutilised their method for the detection of cations in analyticalchemistry and also claim 25 to have found evidence of elements85 and 87 in minerals such as lepidolite and pollucite. P. R.Gennet6,18 in a critical examination of the value of this method,concludes that the results of Allison and his collaborators must beaccepted with the greatest reserve.It is not without interest tofind that last year J. Papish and A. C. Shuman 26 tested the apparatusused by Allison and reported unfavourably on it. Finally, it may bementioned that (Frau) I. Noddack l5 expresses the opinion that theresults obtained by the magneto-optic method are dehitely specula-tive and considers that the discovery of element 87 by Papish isnot yet substantiated. It must be concluded that the evidencefor the discovery of elements 85 and 87 is not very substantial,and that elements 61, 85, and 87 still afford ample scope for theinvestigator.No account of the Periodic Table would be complete withoutsome reference to element 43, named masurium.Althoughmasurium was discovered at the same time as rhenium, there is aremarkable difference in their subsequent history. Very littleis known even now about masurium, but the chemistry of rhenium31 Physical Rev., 1929, [ii], 34, 752; A., 1929, 1210.22 Ann. Reports, 1928, 25, 317.23 Physihl. Z., 1926, 27, 531; A . , 1926, 990.2* Phil. Mag., 1927, [vii], 3, 1199; A., 1927, 610.25 Ann. Reprta, 1932, 29, 300. 26 Science, 1934, 79, 297; A., 1934, 626CARTER AND WARDLAW : THE PERIODIC TABLE. 143is considerable and rapidly developing. W. Noddack, (Frl.) I.Tacke, and 0. Berg2’ estimated that the lithosphere containedof masurium and 10-12 of rhenium compared with 7 xof manganese and 10-2 of iron.Their later revised estimate sug-gested that the two elements masurium and rhenium were presentin equal amounts as 10-9. This assumption makes it still moreextraordinary that so little progress has been made with the studyof masurium. The German investigators detected masurium byX-ray spectroscopic analysis in platinum ores, columbite, sperrylith,gadolinite, and fergusonite, and later 28 in tantalite and possiblyin chrome iron ore, olivine, and pitchblende. They examined1800 minerals and 21 meteorites for the elements 43 and 75. Theevidence for the discovery depends on the identification of theK,,, K,%, and Kp, lines in the X-ray spectra. The wave-lengthsfound were 0.672, 0.675, 0.601, and the calculated values were0.6734, 0.6779, and 0.600 8.respectively. Although the observedvalues are not identical with the calculated, they may be regardedas strong evidence of the presence of masurium, since there are noother elements which could give these results. The most successfulattempt to obtain masurium has been made by W. and (Frau) I.Nodda~k,~~ who isolated a sulphide product containing 0.2-1 yoof masurium during an investigation of columbite. Although thiswas insufficient for an examination of the chemical properties ofmasurium, it served for the identification of the optical arc and sparkspectral lines. Certain observers have had evidence of the presenceof masurium in rhenium concentrates. For example, 5. Hey-rovsky and V. DolejrSelr 30 stated that, in their polarographic studiesof manganese salt solutions with the dropping-mercury cathode,they noted a wave at - 1.15 volts in the deposition-potentialcurves, which they ascribed to masurium.There seems no reasonto doubt the existence of element 43. J. G. F. Druce 31 has madethe interesting suggestion that some rhenium preparations may becontaminated with masurium, and that this may account for someof the discrepancies in the observations and deductions of differentinvestigators.The important additions to our knowledge of protoactiniumwhich have been made in recent years are the justification for thisspecial reference to element 91. It will be recalled that this element27 Naturwiss., 1925, 13, 567; Sitzungsber. preuss. Akad. Wiss. Berlin, 1926,28 Z. angew.Chem., 1925, 38, 1157; A., 1926, 112.29 Metallbiirse, 1926, 16, 2129.30 Chem. Listy, 1926, 20, 4; A., 1926, 258; Rec. trau. chim., 1927, 46, 248;al Science Prog~ea8, 1933, 27, 687.400 ; A., 1925, ii, 939.A , , 1927, 636144 INORGANIC CHEMISTRY.-the eka-tantalum of Mendel6ef-was discovered independentlyand almost simultaneously by 0. Hahn and L. Meitner in 1917 andby F. Soddy and J. A. Cranston in 1918. Not until 1927, however,was the element available in a weighable amount. In that yearA. von Grosse,32 in the Kaiser Wilhelm Institut fur Chemie, isolated2 mg. of pure Pa205, and in 1928,33 carrying out a large-scale pre-paration, he obtained 9 mg. of pure oxide. As protoactinium has ahalf-value period of about 22,000 years, it is obvious that the elementshould be available in much larger quantity if sufficient startingmaterial is used.In 1934 G. Graue and PI. Kading,3* working in0. Hahn’s laboratory, reported that by working up 5.5 tons ofJoachimsthal radium residues they had prepared pure K,PaF,containing 0.5 g. of the element, and A. von Grosse and M. S.A g r ~ s s , ~ ~ a t the same period, described their process whereby theyhad obtained 0.1 g. of oxide. It will be realised that the develop-ment of the process for the isolation of these compounds has furnishedvaluable information concerning the chemical behaviour of thiselement. The details of the method of extraction used by theseinvestigators have been published, but a working description forthe preparation of pure protoactinium compounds cannot begiven in a few sentences.It may, however, be of some interestt o outline, briefly, the principal stages in the process used by vonGrosse .36Natural uranium minerals contain 8 g. of protoactinium for every10 g. of radium, and during the process for radium extractionthe protoactinium accumulates in the residue, which provides abetter starting material than that found in nature. This finalresidue, the so-called Riickriickstande from Joachimsthal, has theaverage composition : SiO,, 60; Pez03, 22 ; PbO, 8 ; Al,O,, 5 ;MnO, 1 ; CaO, 0.6 ; MgO, 0.5%. It also contains small quantitiesof titanium (0~3%)~ zirconium (0.1 %), and hafnium, together withmany other elements. The average protoactinium content is300 mg. of Pa,05 per metric ton (a concentration of 1 : 3,000,000),whereas the richest pitchblendes contain only 200 mg.per ton.The plant process is carried out in three main stages. I n the firststage, treatment with hot hydrochloric acid (25%) extracts fromthe Riickruchtunde the iron, the more basic oxides, and most ofthe lead, leaving a protoactinium concentrate consisting chiefly82 Nature, 1927, 120, 621; A., 1927, 1120; Naturwies., 1927, 15, 766; A.,1928, 495; Ber., 1928, 61, [B], 233; A., 1928, 259.33 See 0. Hahn, Ber., 1935,68, [B], 478; A., 593.34 Angew. Chem., 1934, 4’7, 650; A., 1934, 1186.35 J. Amer. Chem. SOC., 1934, 56, 2200; A , , 1934, 1319.36 Ind, Eng. Chern., 1935, 27, 422CARTER AND WARDLAW : THE PERTODIC TABLE. 145of silica and small amounts of zirconium, titanium, and other lessbasic oxides.This concentrate is fused with sodium hydroxide,and the silica is converted into sodium silicate, which is extractedwith water. The residue, containing most of the protoactinium,is dissolved in acid, and silica (from the insoluble silicates) is pre-cipitated. Soluble zirconium salts and phosphoric acid are nowadded to this acid filtrate, and the protoactinium is precipitatedtogether with zirconium phosphate. The precipitated silica, whichcontains 70% of the protoactinium, is extracted with sodiumhydroxide solution ( 20y0), the residue dissolved in hydrochloricacid, and the protoactinium precipitated from acid solution inthe usual way with zirconium phosphate, ZrP,O,. A characteristicreaction of protoactinium is its complete coprecipitation withzirconium phosphate. This process of A.von Grosse was modifiedby G. Graue and H. K a d h ~ g , ~ ~ whereby important changes weremade in the sequence of the operations-fusion of the Ruckruck-stande with sodium hydroxide preceded the extraction with hydro-chloric acid. Graue and Kading discuss in detail the furthertreatment of the precipitated zirconium phosphate. It is reallya complicated problem of the separation of a tantalum-zirconium-protoactinium mixture. The separation of protoactinium fromthe carrier substance, zirconium phosphate, is effected by crystal-lisation of ZrOC1, from a hydrochloric acid solution, whereby theprotoactinium in the filtrate is enriched.The final purification iseffected by the alternate use of the zirconium and the tantalumreactions, and ultimately the protoactinium is isolated as K,PaF,which gives no X-ray spectrum of foreign elements. To obtain theoxide, Pa205, this complex fluoride is heated with concentratedsulphuric acid, ammonia is added to precipitate the hydroxide,and this is ignited to the oxide.The element has been isolated by A. von Grosse 37 by bombardingthe oxide on a copper target with a stream of electrons in a, highvacuum. The use of 35,000 volt-electrons for a few hours at acurrent strength of 5-10 milliamps. splits the oxide into oxygenand the metal, the latter remaining as a shiny, partly sintered,metallic mass, stable to air. Another method for the preparationof the element is to decompose the halide in a high vacuum on anelectrically heated tungsten filament according to the reaction :ZPaX, = 2Pa + 5X,The protoactinium forms a shiny, greyish-white, partly moltendeposit on the filament.The metal does not oxidise in air, inexpected contrast to metallic radium, and retains its lustre for an37 6. Amer. Chm. SOC., 1934,56, 2200; A., 1934, 1319146 INORGANIC CHEMISTRY.appreciable time.550" by reaction of the oxide with carbonyl chloride :The pentachloride can be prepared readily a tPa,05 + 5coc1, = 5C0, + 2PaC1,The pentachloride sublimes in transparent, nearly colourless, longneedles. The chloride melts to a pale yellow liquid at 301", butsublimes appreciably below its melting point.The complex fluoride,K,PaF,, crystallises in colourless long needles, very sparinglysoluble in water containing hydrofluoric acid (06y0). They arestable in air and can be dried to constant weight at 20" or 100".A survey of the analytical reactions of protoactinium provesdefinitely that the oxide Pa,O, is basic, in contrast to the pentoxidesof tantalum, niobium, and vanadium, which are acidic or amphoteric.This is illustrated by the fact that when a zirconium-protoactiniummixture containing tantalum is fused with potassium carbonate,the tantalum goes, at least partially, into solution, whilst theprotoactinium remains in the residue. Protoactinium is evidentlyless basic than zirconium, for when an acid solution of zirconiumchloride containing a low proportion of protoactinium reacted withan ice-cold solution of ammonium carbonate, some 12% of the zir-conium but only 0.8 yo of protoactinium dissolved.The importance of this work on protoactinium is not restrictedto the fact that it extends in a most interesting way our knowledgeof the chemistry of the elements of Group V.It also gives us newknowledge about the element which is the direct mother-substanceof actinium, and enables us, for the first time, to determine thisimportant atomic weight. The simplest and most accurate wayof obtaining this atomic weight would be by a mass-spectrographanalysis. I n view of F. W. Aston's success with the fluoridesof uranium, tantalum, and niobium, the fluoride PaF, would nodoubt be very suitable for the purpose, but unfortunately its pre-paration is excluded by the relatively large quantity of startingmaterial required.However, using the chemical method, wherebythe ratio K,PaF, : Pa,O, was determined, A. von Grosse 38 hasfound that the atomic weight is of the order 230.6, with an accuracyof This value is in complete agreement with F. W.Aston's results 39 on actinium-lead (Ac-D = 207) obtained by themass spectrograph. For the chemist, this atomic-weight determin-ation has a peculiar interest, as it adds a fourth to the three well-known anomalies of atomic weights, cobalt-nickel, argon-potassium,tellurium-iodine. Thorium (at. no. go), which precedes proto-actinium, has an atomic weight of 232.1.3* Proc. Roy. Soc., 1935, [ A ] , 150, 363.39 Ibid., 1933, [ A ] , 140, 535; A., 1933, 762.0.5 unitCARTER AND WUDLAW : THE PERIODIC TABLE.147A careful study of the Periodic Table must raise the pertinentquestion why the system of elements should end so abruptly a turanium. It is most remarkable that this element, which is con-sidered to have the highest possible atomic number, should have anexceedingly long life, although radioactive, and should be by nomeans rare. It was, therefore, with unusual interest that in 1934the announcement was received from Eome that E. Fermi,40 in-vestigating the products of neutron activation of various elements,had reported the possibility that an element of atomic numberexceeding that of uranium had been obtained. In a later com-muni~ation,~~ Fermi expresses the opinion that further experimentsmade by himself and his collaborators support the hypothesis thatthe 13-minute and 100-minute induced activities of uraniumare due to transuranic elements. He states that the simplestinterpretation consistent with the known facts is to assumethat the 15-second7 13-minufey and 100-minute activities are chainproducts, probably with atomic number 92, 93, and 94 respectivelyand atomic weight 239.Fermi’s interpretation has been subjectedto criticism by various writersY42*43 but it must be emphasisedthat the work of Fermi and his school is carried out with greatcare and considerable ingenuity, and that the conclusions whichthey draw are tested, wherever possible, by a variety of chemicaland physical experiments.The reader will naturally enquire atthis stage whether elements of atomic number greater than 92have ever been definitely identified. The answer must be that,although there are indications that such elements may be formedby neutron activition of uranium, yet the principal workers in thisfield are careful to emphasise the difficulty of obtaining conclusiveproof.About the same time as Fermi’s announcement in 1934, 0,Koblic 44 stated that he had obtained in considerable quantity fromJoachimsthal pitchblende a pure silver salt, AgXO,, where X waselement 93. He described the properties of the element and itscompounds, estimated its atomic weight as 240 from an analysisof this silver salt, and suggested the name “ bohemium ” for thenew element.Certain of the compounds were then submittedE. Fermi, E. Amaldi, 0. d’Ago-stino, F. Rasetti, and E. SegrB, Proc. Roy. SOC., 1934, [ A ] , 146, 483; A . , 1934,1284.4l E. Amaldi, 0. d’Agostino, E. Fermi, B. Pontecorvo, F. Rasetti, and E.Segr6, ibid., 1935, [A], 149, 522; A., 1935, 910.4a A. von Grosse and M. S. Agruss, Nature, 1934,134, 773; L4., 7; PhysiccrlRev., 1934, 46,241 ; J . Amer. Chene. SOC., 1936,57,438; A., 659.43 Angew. Chern., 1934, 47, 653..14 Nature, 1934, 134, 66.4O Nature, 1934, 133, 898; A., 1934, 826148 INORGANIC CHEMISTRX.to (Frau) I. Noddack 43 for report. A chemical and X-ray investiga-tion of the supposed silver and thallium salts RXO, revealed thatelement 93 was entirely absent, and that these substances weremixed salts of silver or thallium vanadate and tungstate with excessof tungstic acid.This claim to the discovery of element 93 hasconsequently been withdrawn. S. R. C. w. w.2 . SOME ELEMENTS AXD COMPOUNDS.Despite the ever-increasing mass of published work, it is notalways realised that our knowledge of some of the most familiarinorganic substances is far from complete, and that there stillremains much to discover about some of the best-known elementsand compounds. It is only recently, by the use of refined physicalmethods, that an insight has been obtained into the detailed structureof sulphur and phosphorus, and that the constitution of bleachingpowder has been elucidated, Again, during the past few years,important extensions have been made to the fundamental chemistryof common elements such as nitrogen and sulphur, for, by theutilisation of improved appliances and new experimental technique,a number of simple derivatives of great theoretical interest havebeen isolated.Finally, the application of modern theoretical ideasto the problems of valency and chemical combination has resultedin striking developments in the field of molecular structures. Inthis section of the Report an attempt is made to deal with specificexamples of advances in these various directions.It is well known that below 96" sulphur is stable in the ortho-rhombic form, and the chemical evidence strongly suggests theexistence of an S8 molecule in rhombic sulphur. An X-ray in-vestigation has shown that the structure of rhombic sulphur isdefinitely molecular.The S8 molecule is a puckered 8-atom ringwhich may be considered as made up of two squares, one turned45" with respect to the other (Fig. 1). The planes of the two squaresare separated by 1-15 A., the S-S distance is 2.12 A., and the bondangle is 105". The closest distance of approach of atoms in neigh-bouring molecules is about 3.3 8. A study of the high-temperatureforms of sulphur has also been made by J. J. Trillat and K. H.Meyer. It is common knowledge that when sulphur is heated t o170" it becomes highly viscous and if cooled, say, by being plungedinto water, an amorphous plastic product results. If threads ofthis amorphous product are stretched, they show double re-fraction, and J.J. Trillat and H. Porestier have found that theyB. E. Warren and J. T. Butwell, J. Chem. Phpsies, 1935,3,6 ; A., 285.Bull. SOC. chirn., 1932, [iv]. 51,248; A., 1932, 462CARTER AND WARDLAW: so- ELEMENTS AND COMPOUNDS. 149give a fibre-diagram. K. K. Meyer and Y. Go3 deduce from anexamination of this diagram that the sulphur atoms are arrangedin long chains linked by covalencies arranged parallel to the directionof stretching (Fig. 2). The relationship between rhombic and elasticsulphur which these results disclose is most interesting, but thedetailed mechanism whereby rhombic sulphur is converted intoelastic sulphur is still under discussion.An important potential source of sulphur is the sulphur dioxideliberated in the course of many industrial processes.During theroasting of zinc, copper, lead, and nickel ores, for example, verylarge amounts of sulphur are lost in the form of the dioxide. Theproblem of obtaining sulphur from such waste gases has been underFIG. 1. F I G . 2.consideration at Billingham, and, as a result, a valuable processhas been evolved, which M. P. Applebey has described in a recentpaper.4 Researches, extending over some years in the laboratoriesof Imperial Chemical Industries Ltd., have solved the difficulty ofconcentrating sulphur dioxide from metallurgical gases, containing3-7% SO,, by the ingenious method of using a sulphite-bisulphitebuffer system which can be regulated t o have a moderately highpE in the cold and a much lower one when hot.This is achievedby the addition of a substance such as an aluminium salt, thehydrolysis of which is much increased by rise of temperature. Ithas been further demonstrated that the almost pure sulphur dioxideso obtained may be nearly quantitatively reduced by coke in accord-ance with the equation :so, + c "= co, + sThis reaction, which has been known for a long time, thoughgenerally overlooked by the text-books, furnishes a stl iking exampleHelv. China. Acta, 1934, 17, 1081; A., 1934, 1296.Chem. a d I d , 1034,53,1007150 INORGANIC CHEMISTRY.of sulphur dioxide as an oxidising agent. The reduction, whichtakes place very rapidly and almost completely at 1100", is exo-thermic, so no external energy has to be supplied when the requisitetemperature has been attained, M.P. Applebey deals with thefar-reaching possibilities that arise from this successful process,and the impression is gained that these developments are probablythe most important which have been made in the heavy chemicalindustries for some considerable time.The reaction between sulphur dioxide and oxygen in aqueoussolution, with or without the presence of allrali, has recently becomeof practical importance in relation to the problem of removingsulphur dioxide from the flue gases of power stations. A reviewof previous work showed that the mechanism of the reaction wasobscure, especially with regard to the possible effect of surfaces.In an important series of papers, R. C. Hoather and C. F. Goodevehave recorded the results they have obtained from a detailed in-vestigation of this subject.The formation of dithionate by the oxidation of sulphurous acidand sulphites is dealt with in a comprehensive study by H.Bassettand A. J. Henry.6 They find that oxidation of sulphurous acidand of sulphites by chlorine, iodine, and hydrogen peroxide yieldsbut very small amounts of dithionic acid, and this is realised onlyunder acid conditions. Oxygen gives dithionate in amounts whichmay be large. The yield depends on the sulphite concentrationand the acidity. During the photochemical decomposition ofsulphurous acid into sulphuric acid and sulphur, no dithionateappears to be formed. The theoretical considerations involvedin the different reactions are carefully discussed.In a previous Report an account was given of the preparationof sulphur monoxide by an electric discharge in a mixture of sulphurdioxide and sulphur vapour a t low pressures.P. W. Schenk7 hasnow shown that it is possible to obtain a gas containing 40% ofsulphur monoxide, mixed with the dioxide, by the direct com-bustion of sulphur. I<. Heumanns in 1883 had observed thatsulphur at 200" was slowly oxidised, with a feeble phosphorescence,and that a peculiar smell was noticed which he ascribed to sulphurmonoxide. He tried unsuccessfully to prove the existence of themonoxide by leading the gas into alkali. Schenk 7 now finds thatoxidation of sulphur with air at atmospheric pressure gives only asmall concentration of monoxide when determined spectroscopically,Trans.Paraday SOC., 1934,30, 626, 630,1149,1156; A., 1934,1086, 1157;J., 1935, 914; L4., 1090.Z. anorg. Chem., 1934, 220, 268; A., 1936, 51.A., 1936, 42.a Ber,, 1883, 16, 139CARTER AND WARDLAW: SOME ELEMENTS AND COMPOUNDS. 151but, by operating a t low pressures with oxygen, concentrationsup to 40% of monoxide may be obtained when the optimum temper-ature for the reaction has been realised. This optimum temperaturemust be determined experimentally. At pressures of 30, 8, and5 mm., the yields of sulphur monoxide have been found to be7, 30, and 40% respectively. Pressures of oxygen lower than5 mm. cannot be used, as the sulphur flame is extinguished. I n arecent communication C. W. Montgomery and L.S. Kassel9 calculatethe equilibrium constants for the following reactions from spectro-scopic data :(a) 2so = s, + o,, ( b ) 2so = so, + +s2They find that, at very low temperatures, the equilibrium liesright over on the left in reactioii (a). In reaction ( b ) they reportthat an appreciable vapour pressure of sulphur monoxide onlycomes into equilibrium with the dioxide and sulphur at about2000" Abs. These findings are in agreement with the qualitativeobservations made by Schenk. As the temperature of the sulphurflame is so low, an equilibrium position in the sense of the reaction( b ) is not attained. It follows, therefore, that the sulphur monoxideformed in (a) is removed from the sphere of reaction before theequilibrium required by ( b ) is operating.Schenk 10 has studied,by density determinations, the decomposition which sulphurmonoxide undergoes into sulphur and sulphur dioxide. His resultsshow, from the pressure changes observed, that when sulphurmonoxide is decomposed according to reaction (b), 64% of the sulphurmonoxide molecules are associated to (SO),.Although the existence of a tetroxide of sulphur has been sus-pected by various investigators, it has only recently been isolated.R. Schwarz and H. Achenbach l1 have now prepared it by theaction of the glow discharge on a mixture of sulphur dioxide andoxygen (in the proportion 1 : 10) at 0.5 mm. pressure. The reactionproducts are passed through two vessels cooled in liquid air, awhite solid being obtained. This is freed from sulphur dioxideand ozone by warming to - 30" in a current of oxygen, the tetroxidethen remaining.The yield from an experiment lasting six hoursis 0.1 g. Sulphur tetroxide is a white solid which begins to de-compose at - 5" with evolution of oxygen, and at 3" it melts withdecomposition, giving oily drops of S,O,. By the freezing-pointmethod a molecular-weight determination in pure sulphuric acidgave a value 95 in close agreement with 96 required by the simplelo P. W. SchenkandH. Platz, 2. anorg. Chem., 1935,222,177; A., 593.l1 Ibibid., 1934, 219, 271; A., 1934, 1183.J . Chem. Physics, 1934,2,417 ; A., 1934,966152 INORGANIC CHE1KISTRY.formula SO4. Schwarz and Achenbach suggest the structuralformula A for the oxide. Although theoretically thistetroxide could be the anhydride of permonosulphuric acid, thereis no evidence that it will undergo hydration to H,S05.Whenthe tetroxide is dissolved in dilute sulphuric acid at O", slow de-composition takes place with oxygen evolution, but no H,SO,appears to be formed. This inability to become hydrated isattributed by Schwarz and Achenbach to the co-ordinative saturatedcharacter of the sulphur. Sulphur tetroxide is an excellent oxidisingagent : it will oxidise aniline to nitrobenzene, and bivalent manganeseto the septavalent state.A. H. Spong l2 has concluded that ordinary sulphur monochlorideis probably a mixture of the two forms (1) S-S<cl and (2) Cl*S*S*Cl.G. Giacomello13 has now studied the reaction of phenol and ofp-naphthol with sulphur monochloride in benzene.From thereaction with phenol he isolated one compound with the probablestructure PhO*S*S*OPh, and from the p-naphthol reaction thederivative C,,H7*0*S*O*C,,H7. On the other hand, from p-chloro-phenol he obtained two products C6H,C~*O~SoS0~*C6H,C1 andC,H4C1*O*S *o*c6H4c1. These results are entirely in agreementwith the view that sulphur monochloride is a mixture of (1) and (2),and if this view is correct, then the hypothetical thiosulphurousacid should exist in two isomeric forms (1) SS<OH and(2) HO*S*S*OH. F. LengfeldI4 some 40 years ago examinedthe action of alcohol-free sodium methoxide or ethoxide on a well-cooled solution of sulphur monochloride in light petroleum. Heobtained one ester, in each case as a colourless oil.A. Meuwsen l5now claims that two isomeric esters can be isolated, one similar tothe colourless oil of Lengfeld, and the other a greenish-yellow oilof different constitution but of the same molecular weight. Thecolourless oil he considers to have the constitution OR*S*S*ORwhereas to the other ester he assigns the formula S=S( OR),.H. Stamm l6 maintains, however, that Meuwsen's greenish-yellowester is merely Lengfeld's colourless ester contaminated with about2.5% of sulphur monochloride, and this would account for thechemical and physical differences which have been noted.R. Scholder and G. Denk17 have prepared the first salt of the0-s=o0-0c1 - +OH - +13 J., 1934, 485; A., 1934, 605.13 Atti R.Accad. Lincei, 1935, [vi], 21, 36 ; A., 614.14 Ber., 1895, 28, 449.1 6 Ibid., p. 673; A., 729.16 Ber., 1935, 68, [B], 121 ; A,, 326.l7 2. anorg, Chew., 1935, 222, 17; A,, 461CARTER AND WARDLAW: SOME ELEXENTS AND COMPOUNDS. 153hypothetical sulphoxylic acid, H2S02. When aqueous solutionsof cobaltous chloride and sodium hyposulphite (Na,S,O,) reactedin the presence of ammonia, ethylenediamine, or pyridine, a darkred solution was formed which, on dilution with water, gave adark brown flocculent precipitate of cobalt sulphoxylate,CoSO,,xH,O, probably in a polymerised form.A. M. Middleton and A. M. Ward 18 have investigated the com-position and properties of precipitated nickel and cobalt sulphides.They find that, with air exclusion, the sulphides formed areNi(SH),, Co(SH),, and Co(SH),, which yield NiS, CoS, and Co,S,when dried in nitrogen.In the presence of oxygen, however,variable addition takes place, initially a t the sulphur atoms in -accordance with the scheme Niaccompanied by intramolecular rearrangement. Drying of theoxygenated sulphides results in a partial elimination of hydrogensulphide and water, and further oxygenation may proceed. Thedried and the undried oxygenated aulphides are the substancesusually obtained in qualitative analytical procedure.Although a peroxide of nitrogen appears t o be formed by theaction of a ailent discharge on a mixture of oxygen and nitrogendioxide,* its existence has hitherto only been indicated by a changein colour of the mixture and the appearance of certain characteristicspectral lines.Now, however, R. Schwarz and H. AchenbachI9have succeeded in preparing pure nitrogen trioxide, NO,, andexamining its properties. The apparatus they employed wasessentially the same as that used by them for their successfulsynthesis of sulphur tetroxide. A mixture of nitrogen dioxide andoxygen in the proportion 1 : 20 at a pressure of 1 mm. was passedthrough the apparatus and submitted to a glow discharge. TheNO, : 0 ratio must be carefully adjusted. Lower oxides of nitrogenare formed unless a large excess of oxygen is present, but too greatan excess gives ozone. The reaction products were condensed invessels cooled with liquid air, and a pale blue condensate wasobtained, apparently a mixture of dinitrogen trioxide and higheroxides. By modifying this apparatus so that the condensing tubeformed part of the discharge tube, they obtained a colourless depositof pure nitrogen trioxide, NO,.It is stable a t - 142", above whichit slowly decomposes into nitrogen dioxide and oxygen. In aqueouBmedia it is relatively stable. For example, at 15-20', the oxidation18 J., 1935, 1459.* The nomenclature used in this article denotes the actual numbers ofatoms of nitrogen and oxygen in the molecule ; e.g., dinitrogen trioxide N,O,,nitrogen trioxide NOb.-Ed.l9 Ber., 1935, 68, [B], 343; d., 457154 INORUANIC CHEMISTBY.value of nitrogen trioxide in sulphuric acid ( N / 5 ) requires about50 hours to sink to zero. Again, when the trioxide is dissolvedin nitric acid (2N) and potassium iodide is added, although iodineis liberated immediately, the reaction reaches completion only after30 minutes.With sodium hydroxide the trioxide reacts thus :ZNO, -+ 2NaOH = NaNO, + NaNO, + 0, + H20The reaction takes place in two stages. In the presence of water,the trioxide is decomposed into the dioxide and oxygen and thedioxide then yields NO,' and NO,'. The trioxide does not function,therefore, as an acid anhydride. Although direct determinationsof molecular weight are impossible owing to the instability of thecompound, the authors consider that it has the monomeric form.They base this opinion on the very low temperature of condensationof the trioxide and its spectroscopic behaviour.Further, theyconsider that it must have a co-ordinatively unsaturated characterfrom the fact that it can be extracted from aqueous media by ether.The distribution coefficient between water and ether is, in fact,1 : 3. As hydrolysis in water is not accompanied by the productionof hydrogen peroxide, the constitution NO,-O-O-NO, is excludedand identity with the dimeric oxide N,O, not possible. Theauthors believe, therefore, that their new trioxide has the formula0 O=N<?, which would be more correctly written as O+N< I 0 0'T. M. Lowry and J. T. Lemon 2o report that when dry dinitrogenpentoxide (N205) is vaporised in a stream of ozonised oxygen andthen passed through a glass tube heated by a small flame, thecolourless gas becomes brown, through the formation of nitrogendioxide, a short distance before the flame is reached.A narrowzone of a dark grey-blue colour is, however, seen hovering at theboundary, and this is preceded by a zone of clear blue. In a longtube the blue flame thus formed " strikes back " from time to timeat the rate of about 10 em. per second to the point at which the gasenters the tube, which is then filled from end to end with brownnitrogen dioxide. When the concentration of dinitrogen pentox-ide is low, the grey boundary between the colourless incoming gas andits pale brown decomposition products remains stationary and doesnot strike back. It is suggested that the formation and disappear-ance of the blue zone may be due to the production and decom-position of it higher oxide of nitrogen; e.g., N20, + 0, =2NO,(blue) + 0,; 2N0, = 2N0, + 0,.The temperature at theboundary is probably below 100". In a study of the binary systemN,O,-N2O5 Lowry and Lemon 21 find that dinitrogen tetroxide2o Nature, 1936, 185, 433 j A., 593. 21 J., 1936, 692; A., 824CARTER AND WARDLAW: SOME ELEMENTS AND COMPOUNDS. 155and pentoxide give a simple freezing-point diagram with a eutecticat 10.8% N,O, and - 1543".During recent years some exceptionally interesting compoundshave been isolated from reactions involving fluorine. G. H. Cady 2,has now investigated the action of fluorine on nitric acid (3N)and thereby discovered the new gaseous compound, NO,F. Inhis experiments, Cady sometimes experienced explosions, but0.Ruff and W. Knasnik23 find that the danger of explosion isminimised by the use of nitric acid of higher concentration, andthat it disappears entirely if pure nitric acid (100%) is employed.At low temperatures, e.g., - 35", the reaction is incomplete, but at + 20" it proceeds quantitatively in accordance with the equationHNO, + F, = NO,F 4- HFThe apparatus used is constructed partly of quartz glass and partlyof ordinary glass. The hydrogen fluoride liberated in the reactionis absorbed by anhydrous potassium fluoride, and the other productsare condensed in receivers cooled with liquid air. The condensateis fractionally distilled at 100 mm. pressure through a quartz-glasscolumn, and the portion passing over at - 79'199 mm. is pureNO,F. Other fractions consist of SiF4, H,SiP,, and H,F,.Amolecular-weight determination by the density method gave thetheoretical value for the molecule N0,F. The fluoride, which isnormally a gas with critical temperature estimated t o be 67.2",condenses to a colourless liquid, b. p. - 45-9"/760 mm., and to awhite solid, m. p. - 175". The density of the solid at - 193.2" is1.951, and that of the liquid is 2.2148 - 0.003114T. Solid orliquid NO,F is exploded by mechanical shock. The vapour pressurehas been measured with a quartz-spiral manometer between - 128"and - 68" and is given by log p = - 1044*9/T + 7.478, and thelatent heat of vaporisation is 4726 g.-cals. per mol. The gas isstable in dry glass or quartz, but with water it gives oxygen andfluorine monoxide together with nitric acid and hydrogen fluoride.It reacts with dilute sodium hydroxide solution (2%), OF, beingliberated :2NO,F + 2NaOH = 2NaN0, + OF, + H,OIf a more concentrated sodium hydroxide solution (20%) is employed,the initially formed fluorine monoxide decomposes in the usualway and oxygen alone is obtained. These experimental findingscharacterise NO,F as tt derivative of the fluorine monoxide, Ol?,,in which a fluorine atom is replaced by the NO, group, i.e.,22 J .Amer. Chem. Soc., 1934,56,2635; A., 1935, 181.23 Angew. Chem., 1935, 48, 238; A., 715; D. W. Yost and A. Beerbower,J . Amer. Chem. SOC., 1935, 57, 782; A , , 715156 INORGANIC CHEMISTRY.Z)-O-F, or in modern nomenclature h;N-O-F. Although 04the reaction of NO$' with water or sodium hydroxide solutiondoes not give an explosion, contact with alcohol, ether, or anilinecauses one immediately.On the other hand, with glycerol, aceticacid, or acetone no reaction is perceptible. Moreover, NO$'is appreciably soluble in acetone. The odour of the new compoundis described as irritating.K. Gleu and R. Hubold% have reinvestigated the per-acidwhich is formed on mixing a nitrite solut?on with acidified hydrogenperoxide and to which Raschig and other investigators have giventhe formula HNO, and the name pernitric acid. Gleu and Huboldprepared the supposed pernitric acid by adding to a solution ofsodium nitrite (1 mol.) and hydrogen peroxide (> 1 mol.) muchice and then the equivalent amount of sulphuric acid (2N), excessof sodium hydroxide being added after two seconds.In the in-tensely yellow solution produced, 70% of the nitrite may be con-verted into the per-acid under the best experimental conditions.To obtain this result it is most important to observe the correctinterval of time between addition of acid and of alkali. Theexcess of hydrogen peroxide, in the presence of sodium nitrite andthe sodium salt of the per-acid, was determined by titration withsodium hypochlorite (0-1N) in alkaline solution in the presence often drops of potassium iodide (0.1N) until the colour of the ruthen-ium-red indicator was discharged. Excess of arsenious oxide(0.1N) was added immediately and back-titrated with sodiumhypochlorite, the same indicator being used, to determine the activeoxygen in the per-acid.The NO,' was determined by reductionto ammonia with vanadyl sulphate, VOSQ,, and distillation intoacid. Under these conditions any nitrate is unaffected. The ratio,active 0 : NO,', was always 1 : 1, proving the presence of per-nitrite HNO,*O and absence of pernitrate. These findings confirmthe views of J. Schmidlin and I?. Massini25 put forward in 1910.It may be mentioned again that the nitrogen trioxide (NO,) recentlyprepared by Schwarz and Achenbach did not prove to be theanhydride of pernitric acid.Phosphorus crystallises in a number of allotropic forms, three ofwhich, the white, the red, and the black variety, are easily dis-tinguished because of their widely differing physical and chemicalproperties.It is well known that white phosphorus is easilychanged into the red variety by heat, light, or X-rays, but that toconvert white into black phosphorus 26 a pressure of 12,000 atmo-a 5 Ber., 1910,43,1162; A., 1910, ii, 498. 24 2. anorg. Chem., 1935,223,305.26 P. W. Bridgman, J . Arner. Chem. Soc., 1914,36, 1334; A., 1914, ii, 647CARTER AND WARDLAW : SOME ELEMENTS AND COMPOUNDS. 157spheres is necessary at a temperature of 200". Recently, blackphosphorus has been made from white phosphorus by a pressureof 35,000 atmospheres at room temperat~re.~' The density ofblack phosphorus is very high, being 2-6-2.7, as against 1.83 forwhite and 2.34 for red phosphorus. All three varieties when heatedgive a vapour composed of P, molecules, which condenses to whitephosphorus.At lower temperatures (100" in a vacuum), however,the vapour of red phosphorus condenses unchanged, but the vapourdensity is so low that no molecular-weight determination has yetbeen made. These facts seem to indicate that white phosphorusis composed of more or less loosely-bound P, molecules, whichreadily break up to form the more stable structures of red andblack phosphorus. It is most difficult to come to a decision inthis matter, for data on phosphorus are confusing and incomplete,FIG. 3.and until recently none of the crystal structures had been satis-factorily worked out by X-ray methods. An important advancehas now been made by R. Hultgren, N. S. Gingrich, and B. E.Warren 28 as a result of their investigation of the crystal structureof black phosphorus. They find that the unit cell of black phos-phorus consists of two double layers, one of which is shown inFig.3. Each atom is bound to three nearest neighbours at 2-18 A.in agreement with the accepted atomic radius of 1-10 A. and withthe co-ordination to be expected from covalent bonding of phos-phorus. Two of the bonds are in the plane of the layer at 99"from one another; the third is between layer halves at 103" 30'from both, making the average bond angle 102". This agrees withthe tendency of bond angles to be nearer tetrahedral for the lighterelements of the periodic group. The decisively covalent characterof phosphorus is clearly shown by the fact that the distance betweenbonded atoms is only 2.18 A.compared with 3.68 A. as the closest27 P. W. Bridgman, Physical Rev., 1934, 45, 844.28 J . Chern. Physics, 1935, 3, 351; A., 919158 INORCANIC CHEMISTRY.approach between atoms in different layers. In arsenic, which isappreciably more metallic than black phosphorus, the bonds areless sharply differentiated ; the three nearest neighbours are a t2.51 A., with three more atoms at 3.15 A. Atomic distributioncurves of crystalline and amorphous black and red phosphorus,obtained by the method of Fourier analysis, furnished a valuableclue to the structure of red phosphorus, for they showed that eachatom formed three covalent bonds in the normal manner. More-over, the fact that the second peak was at practically the sameposition as in black phosphorus suggests that the bond angles arenearly the same.Ortho-salts, such as Na3N04, Na3N03, Na,Zn04, and Na,CuO,,have been prepared 2o by the action of sodium oxide, Na,O, on thesalts of oxy-acids or on weakly acidic metallic oxides.They areusually decomposed by water or carbon dioxide, so cannot be pre-pared from alkali hydroxides or carbonates. The proof of theexistence of these ortho-salts has been established by X-ray analysis.The preparation of &,NO, brings out an interesting relationshipbetween nitrogen and phosphorus. However, as 4 is the maximumco-ordination number of nitrogen, it will, presumably, not bepossible to prepare the nitrogen analogue of the hypotheticalH,PO,, esters of which have been isolated.30The constitution of bleaching powder has been the subject ofinvestigation and speculation for many years.The older methodsof examination, depending on such properties as solubility, vapourpressure, mode of chemical decomposition with heat or acids of thecarbonic and hydrochloric type, have been used at various timesbut with no great measure of success. The problem has now 31 beenattacked by phase-rule studies, by extended microscopic examin-ation, and by the use of X-ray powder photographs. As a resultof the phase-rule work, all the pure compounds which could beisolated under equilibrium conditions from the system CaO-CaC1,-Ca(OCl),-H,O below 40" have been defined and used as a basis forcomparison with the solid phases present in bleaching powder.It has been established that the first stage, in the reaction betweenchlorine gas and calcium hydroxide in the preparation of bleachingpowder, is the formation of the basic hypochlorite Ca(OC1),,2Ca(OH),and the basic chloride CaCl,,Ca( OH),,H,O.On further chlorination,the former is converted into another substance which appears to be29 E. Zintl, M. Morawietz, and G. Woltersdorf, ~ a t U W i S S . , 1935, 23, 197 ;30 L. Anschutz and W. Broeker, Ber., 1926, 59,2848; A., 1926, 146.31 C. W. Bunn, L. M. Clark, and I. L. Clifford, Proc. Roy. SOC., 1935, [-4],E. Zintl and W. Haucko, Z.physika1. Chem., 1935, 174, 312; A., 1936, 16.151, 141; A . , 1214CARTER AND WARDLAW : SOME ELXMENTS AND COMOUNDS. 159a mixed crystal whose chief constituent is calcium hypochlorite.Ordinary bleaching powder, containing about 35% of availablechlorine, is a mixture of this hypochlorite mixed crystal with thebasic chloride CaC12,Ca( OH),,H,O.On further chlorination, thelatter is partly but never completely converted into hydrated calciumchloride (usually the tetrahydrate, CaC1,,4H20) whilst the hypo-chlorite mixed crystal persists, with gradually changing properties.The most highly chlorinated sample which was examined consistedof hypochlorite mixed crystal, CaC1,,4H20, and CaCl,,Ca( OH),,H,O.The non-deliquescent nature of ordinary bleaching powder and thedifficulty of introducing more than 35% of available chlorine intothe solid are due to the presence of the basic chlorideCaCI,,Ca( OH),,H,O,which appeass to be a very stable substance.R.K. Bahl and J. R. Partingfon3, have reinvestigated thelower oxides and sulphates of iodine. Contrary to some statementsin the literature, which are reproduced in text-books, they provethat the interaction of iodine and cold concentrated nitric acid(d, 1-5) produces the pentoxide I,O, and not the dioxide. Inconformity with the weakly basic properties of iodine, they fmdthat basic saltsare more stable than the normal ones. They wereunable, however, to obtain Chrbtien’s sulphate, Iz0,,S03,&H,0,by heating a mixture of iodic acid and concentrated sulphuric acidtill iodine is evolved. The analysis showed that the product wasprobably I,0,,H,S04 containing some I,O,,H,SO,.Although numerous attempts have been made to prepare com-pounds of the rare gases, practically all investigations have servedonly to show the inertness of these elements.P. VillardF3 however,in 1896 claimed to have obtained an unstable hydrate of argon,and since then hydrates of krypton and xenon have been reported.Prompted by the idea that boron, in the trifluoride, BF,, is veryreactive by reason of its incomplete octet, H. S. Booth and K. S.Willson 35 have examined the system argon-boron trifluoride bythermal analysis. A graph of the freezing points against composi-tion exhibited maxima and minima. The maxima correspondedto the ratios A,BF,; A,2BF3; A,SBF,; A,6BF3; A,8BF3; andA,16BF3, indicating compound formation, but the compoundsare unstable and dissociate above their melting points. From theshape of the curve, the ratio A,2BF3 appears to be the most stable.32 J., 1935, 1258; A., 1334.33 Compt.rend., 1896, 123, 377; A., 1897, ii, 31.34 R. de Forcrand, ibid., 1923, 176, 365; 1925, 181, 15; A., 1923, ii, 239;35 J. Amer. Chem. SOC., 1935, 57, 2273.1925, ii, 812160 INORGANIC CHEMISTRY.The conclusion that the association of argon with the boron fluorideis of the type BF, +-A analogous with BF, ,+-NH, must beaccepted with reserve. The function of the BF, may be similarto that of water in the hydrates of the inert gases. In N. V. Sidg-wick’s 36 opinion, the water is held by the van der Waals forces inthe crystal along with those of the solute, and the simple numericalratio of the different kinds of molecules merely reflects the geo-metrical regularity of the crystal.So far, no exception has been found to the generalisation that allelements with a covalency of 6 have the six valencies arrangedin the form of an octahedron.When, however, quahicovalentatoms are considered, no such simple generalisation is available.It will be recalled that in 1931 L. Pauling 37 applied wave-mechanicalmethods to the problem of covalent linkages and showed that for4-covalent atoms, in which electrons from the first two sub-groups(s and p ) of the outer level are used in chemical bonds, the stableconfiguration is tetrahedral. In the case of the transition elements,however, one or more electrons used in binding may belong to theci! sub-group of the incomplete inner level, and in these cases, thefour covalencies may be distributed in a plane.Moreover, sincethe d electrons are chiefly responsible for the magnetic moment ofthe atom, sharing of them should reduce this property, so that4-covalent nickel compounds should be diamagnetic. Pauling ’sconclusions have been criticised by W. Heisenberg 38 and others,but appear to be essentially correct. The point to be recognisedin the case of the transition elements is that the results are probablypermissive, i.e., they show that the metals in question may have,but not necessarily must have, a planar distribution of valencies.That this interpretation is correct is indicated by some recentwork of H. M. Powell and A. F. They examined the com-plex salt Cs,CoCl, by X-ray analysis, and found that the groupCoC1, had an approximately regular tetrahedral configuration,thereby proving that the transition element cobalt can actuallybe tetrahedral when 4-covalent.To Pauling belongs the credit of first suggesting that nickel inits 4-covalent state may have a planar distribution of valencies,and it is remarkable that Werner omitted it from the list of elementswhich he predicted would give planar structures.Pauling’s con-clusion that 4-covalent nickel should be planar and diamagneticreceived strong support from the isolation, by S. fhgden 40 in 1932,36 “ The Covalent Link in Chemistry,” 1933, p. 29.37 J . Arner. Chem. SOC., 1931,53,1367; A., 1931,670.38 See Ann. Reports, 1931, 28, 367..J., 1935, 359; A., 570. c0 J., 1932, 246; A., 1932, 272CAXTER AND WARDLAW: SOME ELEMENTS AND COMPOUNDS. 161of two diamagnetic compounds of nickel with benzylmethylglyoxime.As a matter of historical interest, it should be mentioned that in1910, L. A. Tschugaeff 41 discovered that nickel bis(monomethg1-glyoxime) could occur in two isomeric forms, but he did not suggestthat a possible explanation of the isomerism lay in the planar dis-tribution of the nickel valencies. Recently, H. J. Cave11 and S.Sugden 42 have shown that the occurrence of pairs of isomeridesappears to be general for the nickel derivatives of unsymmetricalglyoximes, and that the explanation must be that nickel is capableof forming 4-covalent compounds of planar type. F.P. Dwyerand D. P. Mellor43 have recorded the preparation of two innercomplex compounds of palladium with benzylmethylglyoxime, andadduced evidence to show that these substances are cis- and trans-isomerides (I and 11) of bis-anti-benzylmethylglyoximepalladium.C,H,*CH2--#---#--CH, CGH, *CH,-G--G-CH,O t N N-OH O+-N N-OHr\ / sHO-# M->O Ot# #-OHCH,-C---C-CH,-C,H, C,H,*CH2-C-C-CH,Further support for Pauling’s predictions has been obtained from anexamination of the nickel and palladium derivatives of salicyl-aldoxime.44 These compounds have been shown, by X-ray analysis,to be isomorphous and to have a, trans-planar structure. Moreover,the nickel compound has been found to be diamagnetic. A strikingexample of planar nickel in a co-ordination compound of quite adifferent type has been discovered in an examination of the dithio-oxalates of nickel, palladium, and platinum.45 The anhydrouspot assiuin nickelodit hio-oxalat e (111) is completely isomorp houswith the corresponding palladium and platinum derivatives, and a,detailed X-ray examination has shown that the valencies of the4-covalent nickel, palladium, and platinum are in a plane with themetal atom.4 1 J .Rum. Phys. Chem. SOC., 1910, 42, 1466; A., 1911, i, 261; Chem. Zentr.,1911, 82, i, 871.42 J., 1935, 621; A., 980.43 J , Amer. Chem. SOC., 1935, 57, 605; A., 752.44 E. G. Cox, F. W. Pinkard, W. Wardlaw, and K. C. Webster, J., 1935,450 ;4 5 E. (2,. Cox, W. Wardlaw, and K. C. Webster, J , , 1935, 1475.A . , 684.RE(:P.-VOL. XXXJI - 162 INORGANIC CHEMISTRY.In view of the fact that compounds of 4-covalent cobalt may betetrahedral, the question naturally arises whether the 4-co-ordinatedcompounds of nickel, palladium, and platinum are invariablyplanar, If Pauling's prediction is true that 4-covalent compoundsof the transition elements would be diamagnetic when the fourelectron-pair bonds lie in a plane, then some recent work by R.B.Janes 46 on the magnetic susceptibilities of typical palladium deriv-atives indicates that palladium is invariably planar. He examineda wide range of derivatives, of which the following are typical :Group 1. Palladous salts with four other groups in the molecule :PdC12,2H20 ; PdC12,2NH, ; K2PdC1, ; K,Pd(CN),.Group 2.Palladous inner complex salts : palladium dimethyl-glly oxime.Group 3. Palladous salts where a double molecule is present :In every case the magnetic susceptibilities were diamagnetic.The corresponding platinum compounds have been less extensivelyin~estigated,~' but the several salts which have been measured areall diamagnetic. This physical evidence is in entire agreementwith the available X-ray and chemical evidence, and in view of thediverse nature o€ the compounds which have been studied, thereappears to be no doubt that the planar configuration is quite generalfor 4-covalent compounds of bivalent palladium and platinum,and it can only be modified in very special cases, such as may arisewith ter- and quadri-dentate groups.The evidence from magnetic susceptibility measurements in thecase of nickel, however, indicates that 4-covalent nickel is notinvariably planar.Nickelous salts of the type of Group 1 (above)are paramagnetic, except Ni(CO), and K,Ni(CN), which are dia-magnetic. If, therefore, Pauling's reasoning is sound, then in thecase of nickel only a few molecules of the type of Group 1 are planar,in contrast to the cases of palladium and platinum, where the planarconfiguration is always assumed. This conclusion, that the dis-tribution of the valencies in compounds of 4-covalent nickel maybe either tetrahedral or planar, is in agreement with the recentdiscovery that quadricovalent cupric compounds may be planar.In 1926, W. H. Mills and R. A. Gotts48 showed that 4-covalentcopper in its benzoylpynxvic acid derivative gave rise to opticalactivity, and so presumably belongs to the tetrahedral type.Now,E. G. Cox and K. C. Webster 49 have examined by X-ray analysis[Pd(N~,),C1212'4 6 J . Amer. Chem. Soc., 1935, 57, 471; A., 573.47 D. M. BOSB, 2. Physik, 1930, 65, 677; A., 1931, 25.48 J., 1926, 3121; A., 1927, 149.49 J., 1935, 731 ; A., 920CARTER AND WARDLAW: SOME ELEMENTS AND COMPOUNDS. 163a range of chelated 4-covalent compounds of bivalent copper,including the copper salts of acetylacetone and benzoylacetone,and have definitely established that these substances possess c2planar structure. The result is of interest from another point ofview, for S. Sugden has shown that a number of compounds ofthis type are paramagnetic.According to Pauline;, a planarconfiguration is to be expected when s, p , and d electrons are in-volved in valency bonds. It is possible, therefore, that bivalentcopper (at. no. 29) may possess a complete 3, sub-group of tenelectrons, some being shared, instead of an incomplete sub-groupas is usually supposed. This would involve one unpaired electron1 2 2 3 3 3 - 4-21 21 62 21 62 f in the fourth principal quantum level, givingrise to a paramagnetic moment of the same order as that actuallyobserved by S. Sugden.50The structure proposed by Werner for platinous compoundsof the type PtA,B, was that the valencies had a planar arrange-FIG. 4./ Phment. A test of this, and a differentiation between a planar and atetrahedral distribution of valencies, is provided by the substitutionderivatives of bisethylenediaminoplatinous salts [Pt enz] X,.Inan important communication by W. H. Mills and T. H. H. Q~ibell,~lthe preparation of the diphenyl dimethyl derivatives has beendescribed and the optical activity of the compounds (see Pig. 4)leaves no doubt that the planar imangement proposed by Werneris the correct one. The salts investigated proved capable of re-solution into antimeric optically active forms showing a high degreeof optical stability. The regular tetrahedral arrangement is therebyexcluded, and no reason exists for inferring pyramidal rather thanthe more symmetrical planar configuration. The authors mentionthat the iodide and chloride crystallise with water of crystallisation,but express the opinion that there is no reason to doubt that thecentral platinum atom of the complex cation is truly 4-covalent.The planar arrangement of the platinum valencies with the inter-valency angle of 90" is shown to give rise to a practically strainlessring, whilst an arrangement with a tetrahedral valency angle wouldJ., 1932, 161; A , , 1932, 324.61 J., 1935, 839; A., 1057164 INORGANIC CHEMISTRY.create a very considerable strain in a five-atom ring composedof carbon and nitrogen atoms and one 4-covalent platinum atom.The structure and configuration of certain diamminopalladiumcompounds have been studied by chemical and X-ray methods,and the findings are fully in agreement with Werner’s view. Adeep red, highly crystalline form of Pd(NH,),Cl,, has been shown 52to have a trans-configuration like the familiar yellow powder form,their difference being due essentially to different crystal structuresbuilt up from the same (truns-) molecules.Recently, it has been shown 53 by an X-ray analysis that theconfiguration of the 4- covalent compound of quadrivalent platinum,Pt(CH,),Cl, is tetrahedral.This is a result of unusual interest,for it indicates that the principal valency of an atom may be a factorof importance in deciding the configuration of its 4-covalentderivatives.F. G. Mann and D. Purdie 54 have published some valuableexperimental data on the parachors of palladium and mercuryin simple and complex compounds. They find that, in certainseries of organo-metallic compounds, both simple and complex,the metal atom shows an apparent parachor which falls steadilyas the homologous series is ascended, and may ultimately reach aconstant value.For example, in the homologous series ( SR,),PdC12,the parachor of palladium fell from 36 for the methyl to - 7 forthe n-amyl compound. Another point of interest has arisen in thisinvestigation. The dipole moments of the three ethyl compoundsof the chloro-series (SR,),PdCl,, (PRJ2PdC1,, and (AsR,),PdC12,vix., 2-27, 1-05, 1.04 ( x e.s.u.), strongly support the assump-tion that they are all stable truns-compounds. The symmetricaltrans-compounds should have a dipole moment closely approachingzero, whereas the cis-isomerides should have very high moments.This conclusion is in agreement with the X-ray and chemical evi-dence relating to the thio-ether compounds of platinous and palladouschlorides. 55G.T. Morgan,5s in an address to the Chemical Society, has dealtwith some important advances made in recent years in the studyof the rarer elements. He is, himself, an outstanding leader inthis field of work, and the results which he and his colleagues have52 F. G. Mann, (Miss) D. Crowfoot, D. C. Gattiker, and (Mrs.) N. Wooster53 E. G. CoxandK. C. Webster, 2. Krist., 1935, [A], 90, 561.54 J., 1935, 1549.s5 E. G. Cox, H. Saenger, and W. Wardlaw, J., 1934, 182; A . , 1934, 397;s 6 -7.. 1935, 554; A., 716.J . , 1935, 1642.H. D. K. Drew and G. H. Wyatt, J . , 1934,56; A., 1934,284HEDUES : NON-FERROUS ALLOY SYSTEMS.165accumulated form the main topic of the address. Certain seams01 Northumbrian coal give an ash containing up to 1% of germaniumand 0.05% of gallium, and G. R. Davies, working in the Teddingtonlaboratories, has elaborated a process for the extraction of boththese rare elements. The germanium is distilled over with acidas tetrachloride, whilst gallium trichloride remains. Rheniumhas been extracted from Australian molybdenite by a lengthyprocess involving fractional volatilisation, and ultimate separationwith organic reagents such as 8-hydroxyquinoline and dipyridyl.The address concludes with some reference to co-ordination com-pounds of ruthenium, and a plea for a wider investigation of therarer elements ".. . for discoveries will from time to time be madein the application of these materials which will redound to thecredit of our science, and the good of the community."S. R. C. w. w.3. NON-FERROUS ALLOY SYSTEMS.Progress in the knowledge of alloy systems has not previouslybeen reviewed in these Reports. From the viewpoint of themetallurgist, the subject is a vast one, and it has been necessary forthe purpose of this Report to restrict the field to certain aspectswhich are clearly of interest to chemists. The policy adopted hasbeen to disregard a great amount of more or less isolated observationson particular alloys, and to describe what has been done during thelast five years or so on the examination of non-ferrous alloy systemsfrom the constitutional point of view, with special reference to theformation of intermetallic compounds. It is natural, therefore,that mainly binary systems are considered, and that much work ofindustrial importance, of interest to the metallurgist and theengineer, falls outside the scope of the Report.Methods of Investigation.-Although thermal analysis and micro-graphical examination continue to be of fundamental importancein the study of equilibrium diagrams, there is evidence that moreuse is being made of the investigation of other properties of alloysystems as accessory means, and that such wider investigations haveled to the reconstruction of some of the older diagrams.The salientfeatures of these methods have been discussed by H. Scott,lJ.L. Haughton,2 and W. Guertler.3 C. Sykes4 has pointed outthat the standard cooling-curve methods may give unreliable resultswhen applied to transformations involving atomic rearrangement1 First Comm. New Internat. Assoc. Test. Hat., 1930, [A], 339.2 Ibid., p. 316.3 Pmc. Zurich Congr. Intemt. Assoc. Teet. Mat., 1932, 1, 469.4 Proc. Roy. SOC., 1935, [A], 148,422; A., 576166 INORGANIC CHEMISTRY.in a homogeneous solid solution, and has described a modified,double differential cooling-curve method.Outstanding among the more modern methods is the X-raydetermination of alloy equilibrium diagrams. The value of theX-ray mebhod has been emphasised by A. We~tgren,~ inasmuch asit makes possible, not only the determination of the nature of thecrystal structure and dimensions of the crystal lattice of the differentphases existing in the alloy system, but also the fixing of the positionof the phase limits.There is the further advantage that someinsight into the chemical characteristics of the phases is given, whichthe earlier metallographic methods could do only very incompletely.The value of the electrical conductivity method has been discussedby W. Hume-Rothery ; advantages are claimed in the detection ofvery small ranges of solid solubility and in the fixing of phasetransformations which are combined with hysteresis or small thermaleffects. The theory of the electrical conductivity of alloys has beendiscussed,' and the rule that the atomic increase in resistance isgreater as the distance between the elements in the periodic systemincreases has been confirmed for a series of gold alloys.The study of constitution by magnetic measuremente has beenreviewed by A.Kussman,8 G. Grubeyg and E. Vogt.lo The magneticmethod has been used in the study of a series of alloy systems,ll andthe existence of the compounds SnSb, CdSb, ZnSb, and Sn,T1 indicatedby abrupt changes in the slope of the susceptibility-compositioncurves. Y. Shimizu l2 has directed attention to the great effect ofadsorbed gases on magnetic susceptibility results, and it appearsthat the curious results obtained in some of the earlier investigationsare due to the neglect to melt and anneal in a vacuum. Shimizufound that, in alloys which form continuous solid solutions, themaximum deviation of susceptibility from the values calculatedfrom the additive rule is small.With eutectic alloys, with solubilityon both sides, the susceptibility-composition curve is linear in thc?range of eutectic composition and slightly curved in the range ofsolid solution. The magnetic susceptibility-composition curves for5 2. Metallk., 1930, 22, 368; Trans. Amer. Inst. Min. Met. Eng., Inst.Metals Div., 1931, 13; Angew. Chem., 1932, 45, 33; Proc. Zurich Congy,Internat. Assoc. Test. Mat., 1932, 1, 484; B., 1931, 978.8 Metallwirt., 1929, 8, 1243; A., 1930, 1106.7 G. Grube and J. Hille, 2. anorg. Chem., 1930, 194, 179; A., 1931, 158;8 2. Metallk., 1934, 26, 25 ; B., 1934, 407.9 Ibid., 1935, 27, 194.11 F. L. Meara, Physical Rev., 1931, [ii], 37, 467 ; Physics, 1932, 2, 33 ; A.,12 Sci.Rep. T d h h I m p . Univ., 1932, 21, 826; A., 1933, 455.L. W. Nordheim, Physical Rev., 1930, [El, 35, 1430; A., 1931, 1361.lo Ibid., p. 40.1932, 686HEDGES : NON-FERROUS ALLOY SYSTEMS. 167several alloy systems of gold 1, and copper 14 have also beendetermined.A few papers report the application of electropotential measure-ments to the determination of constitution. F. Griengl andR. Baum l5 have constructed isopotential lines for the systemgold-tin-mercury in a triangular phase diagram. Although thecurves give no evidence of AuSn or AuSnz, these compounds areindicated by discontinuities in potential in the binary system,suggesting that they are partly dissociated in mercury. Potentialstudies of thallium-bismuth alloys in fused acetates have beenmade,16 and the existence of Bi,T1 indicated.A. Glazunov hasmade an interesting application of the electropotential niethod tothe determination of the phase structure of metallic coatings byanodic dissolution. Since each phase has its own potential, whichremains constant during its dissolution, the composition and thick-nesses of the phases can be determined from the lengths of theindividual potential values (horizontal positions in the graph) andthe intervals between them, provided the course of the potentialcurves of the binary system in question be known. Thus thepresence of Zn,Fe and probably ZnPe, in hot-dipped zinc coatingson iron has been shown.The interpretation of heats of mixture of molten metals has beenundertaken by M. Kawakami,l* who found that with a few excep-tions heat is evolved when the metals form intermetallic compounds,whilst heat is absorbed when solid solutions are produced.Optical properties have so far played little definite part in theexamination of alloy systems.S. Ueno I9 has shown, however,that the curve of intensity of reflexion of silver-aluminium alloyshas a maximum corresponding with the compound AIAg,, a breakat AlAg,, and a minimum at the eutectic. Similar investigationsof the alloys of aluminium with magnesium20 indicate a highreflectivity for Mg,Al,.The cementation method, in which the constituents are heatedtogether in a vacuum at temperatures near the solidus, has beenapplied to several alloy systems by I;.Loslciewicz 21 and has led tol3 E . Vogt, Ann. Physik, 1932, [v], 14, 1 : A., 1932, 907.1 4 H. F. Seemtmn, 2. Metalllc., 1932, 24, 299.l5 iionatsh., 1932, 61, 330; A., 1933, 127.16 A, Olander, 2. physikal. Chem., 1934, [ A ] , 169, 260; A., 1934, 954.1 7 Trans. Paraday Xoc., 1935, 31, 1262.18 Sci. Rep. Tdholcu Imp. Univ., 1930, 19, 521 ; A., 1932, 296.19 Mem. Coll. Sci. Kydt6 Imp. Ul~i.d., 1930, 13, 141 ; A., 1930, 681.20 J. Wulff, J . Opt. SOC. Amer., 1934, 24, 223; A., 1934, 1086.21 Przeglqd Gorniczo-Hutniczy, 1929, 21, 583 ; Przeglyd Techrziczy, 1930, 09,508168 INORGANIC CHEMIST&Y.suggested modifications of the diagrams. It appears from thiswork that the formation of a eutectic during cementation is possibleonly at temperatures above the melting point of the eutectic.Cementation below the melting point can occur only when thecementing metal has a solid solubility in the metal to be cemented.By similar technique with aluminium alloys, M.Bosshard 22 hasconfirmed the existence of the ternary compounds Al,Pe,Si,,AI,Cu,l?e, A15NiCu2, and Al,Mg,Cu.Structure of the Phases.-Reference has been made to the valueof X-ray analysis in the detection of phases and determination oftheir structure. G. Sachs23 maintains that a transformation inalloys generally consists of two partial processes, vix., change oflattice structure and rearrangement of the atoms, and shows thatthese processes can be studied separately by X-ray investigation.The kinetics of lattice transformation are governed by (1) thermalformation of nuclei and crystal growth (at high temperatures),(2) regular change of the lattice and crystal growth (at moderatetemperatures), or (3) regular change of the lattice alone (at lowertemperatures).The effect of thermal agitation on atomic rearrange-ment in alloys has been discussed by W. L. Bragg and E. J. Wil-liam~.~* The ordered has a lower potential energy than thedisordered structure, but thermal agitation promotes disorder.Order sets in abruptly at a critical temperature, and increases asthe temperature is lowered, becoming complete only at absolutezero. The sudden onset of order causes a sharp inflexion in curvesrelating resistivity, lattice spacing, and specific heat with tem-perature.Such inflexions simulate a phase change, althoughackually there is no such change.The effect of additions of one metal on the lattice structure ofanother has been studied.25 W. Hume-Rothery 26 has shown thatthe addition of cadmium, indium, tin, or antimony to silver changesits lattice structure t o an extent which is proportional to the valencyof the added element. The question whether the change in latticeconstants in the formation of solid solutions depends on the grainsize has beenW. Hume-Rothery2* pointed out that the compositions of the22 Aluminium, 1935, 17, 477.23 2. Metallk., 1932, 24, 241; A., 1932, 1196.24 Proc. Boy. SOC., 1934, [ A ] , 145, 699; A., 1934, 954.25 E. R. Jette, Amer. I n s t . Min.Met. Eng., 1934, Tech. Publ. No. 560, 1-26 Nature, 1935, 135, 1038; A., 919.27 E. Schmid and Q. Siebel, Metallwivt., 1932, 11, 685; A., 1933, 1110; U.28 J . Inet. Metale, 1926, 35, 295; A,, 1926, 356.16; A., 1935, 24.Dehlinger and 9. Wicst, ibid., 1933,12,2; A., 1934, 249HEDGES : NON-FERROUS ALLOY SYSTEMS. 169@-phases of many binary alloys are such that the ratio of valencyelectrons to atoms is approximately 3 : 2. The generalisation hasbeen extended by A. J. Bradley 29 to the y-phases of certain alloys,where the ratio of valency electrons to atoms is found t o be 21 : 13.Similarly, the ratio for a number of &-phases is 7 : 4. The validityof these rules has been confirmed 30 for a number of binary alloys ofcopper, silver, and gold.H. Perlitz 31 points out that, since theratio is always greater than 1, a necessary condition for the existenceof these structures is that one of the metals contributes at least2 valency electrons and the other component contributes not morethan 1 valency electron t o the lattice structure. The possiblesystems of alloys that can be formed in accordance with theserequirements have been worked out.Resulting from the study of a large number of binary alloysystems, Hume-Rothery and his collaborators 32 have been able toshow that, if the atomic diameter of the solute differs by more thanabout 14% from that of the solvent, the solid solution is restrictedto a few atoms per cent.; but when the size factor is favourable asolid solution may be formed, in which the solubility limits generallyobey valency laws, the solubility becoming less as the valencyincreases. Under these conditions the maximum solid solubility isdetermined mainly by the concentration of valency electrons, andthis principle permits the approximate calculation of solubilitylimits in certain ternary alloys.A new approach to the problem of the chemical bond betweenmetals has been suggested by J.D ~ r f m a n . ~ ~ Assuming that theatoms of copper, zinc, aluminium, and tin entering the nickellattice become singly ionised, he calculates that the negative valuesof the magnetic moments of these foreign atoms correspond with thenumber of valency electrons left attached to the corresponding ion.I n an examination of the systems aluminium-copper, antimony-silver, cadmium-tin, cadmium-zinc, copper-silver, and lead-tin,D.Stockdale34 found no evidence for his supposition that in abinary eutectic the atoms of the two elements are present in asimple ratio. Recently, however, he 35 has put forward a series of29 Phil. Mag., 1928, [vii], 6, 878; A., 1929, 125.30 A. Westgren and G. Phragmh, Trans. Paruduy SOC., 1929, 25, 379; A.,1929, 987 ; A. Westgren and W. Ekman, Arkiv Kemi, Min. Cfeol., 1930, [B],10, [ii], 1 ; A., 1931, 900.31 J . Chem. Physics, 1933, 1, 335; Actu Comm. Turtuensis, 1933, [A], 24,(2), 1; A., 1933, 118.92 W. Hume-Rothery, G. W. Mabbott, and K. M. C. Evans, Phil. Trans.,1934, 233, 1 ; A., 1934, 725.33 Nature, 1932,130, 506. 54 J . Ins€. hdetale, 1930,43, 193; A., 1930, 537.3 5 Proc.Roy. Soc., 1935, [A], 152, 81.F 170 INORGANIC CHEMISTRY.empirical rules, which, although not exact, are claimed t o givemore accurate results than the majority of those that have beenobtained experimentally in this connexion. (a) I n a saturatedsolid solution at the temperature of the eutectic or peritectic thereis a simple integral relation between the numbers of solvent andsolute atoms. (2) There is a similar relation in a saturated solidsolution in contact with a second solid phase at the temperature oftransformation of the second phase. (3) I n copper- and silver-richalloys the solubilities a t the above two temperatures are simplyrelated, and it is possible t o predict the solubility at the lowertemperature if that at the higher is known.(4) I n a eutecticmixture the elements are present in a simple integral atomic ratio.( 5 ) In a eutectic mixture the ratio of the numbers of atoms,irrespective of their kind, in the two phases is simple.A different angle on related problems is provided by work onthe atomic heats of alloyed metals in the form of solid solutions orintermetallic compounds.36 In both cases deviations from theadditive rule have been noted. I n a comparison of the heat contentsof 25 intermetallic compounds with the sum of the heat contentsof their components a t different temperaturesY37 an increase in theheat content of the compound was observed in 14 and a decreasein 8 compounds; in the remaining 3 compounds the differencechanged its sign with change of temperature.If in all cases theheat content of the compound were greater than the sum of thoseof the components, the conclusion might be reached that the surplusheat content should correspond with the energy for the vibrationof molecules, Le., the lattice of the intermetallic compounds wouldbe built up of molecules, not of atoms. This is, however, not thecase.The volume changes accompanying the formation of inter-metallic compounds have been studied.38 Published data on themolecular volume of intermetallic compounds and on the atomicvolumes of their component metals seem to show that metals whichcan be strongly compressed mechanically undergo a contractionwhen they enter into an intermetallic compound, whilst metals whichare difficult to compress do not.F.H, Jeffery 39 has applied an interesting thermodynamical36 J. A. Bottema and F. M. Jaeger, Proc. K . Akad. Wetensch. Amsterdam,37 G. Tammann and A. Rohmann, 2. anorg. Chem., 1930, 100, 227; A.,38 W. Biltz, Z . Metallk., 1934, 26, 230; A., 1935, 158.3* Trans. Paraday SOC., 1930, 26, 86, 587, 588; 1931, 27, 136, 137, 188;1932,&8,452, 456, 667, 705; 1933,29, 650; A., 1930, 406, 1360, 1361; 1931,418, 676; 1938, 566, 007, 9S9; 1933,454.1932, 35, 916, 929; A., 1933, 18.1932, 986HEDGES : NON-FEB;ROUS ALLOY SYSTEMS. 171method to the study of a number of binary alloy systems. Hededuces for a two-component, two-phase system consisting of a,solid and a liquid phase, each of which is a dilute solution of onemetal in another, the relation log (1 - n') - log (1 - n) =L/RT - L/RT,, where L is the latent heat of fusion of the solvent,To the freezing point, R and T have their usual significance, n isthe molar fraction of the solute in the liquid, and n' that in thesolid solution.Application of this equation t o solutions of leadin tin, tin in lead, and cadmium in tin shows that in all cases thesolute is monatomic and no intermetallic compounds are present.In the copper-tin system thermodynamic considerations show thatthe a-phase consists, in both the solid and the liquid state, of asolution of Cu4Sn in monatomic copper; the p-phase is a solidsolution of monatomic tin in monatomic copper; the 3-phase inthe solid state is the compound Cu3Sn, but in the liquid state itconsists of a solution of CuaSn in monatomic tin; the €1-phase is asolid solution of Cu,Sn in monatomic tin.When applied to thecopper-zinc alloys, the method indicates that the liquid solutionsin equilibrium with the a- and the @-solid solution consist of CuZn,dissolved in monatomic copper, that the a-solid solution consistsof CuZn, dissolved in monatomic copper, and the p-solid solutionof CuZn, in monatomic copper. The liquid and solid solutions inthe copper-gold and copper-silver systems are derived from mon-atomic molecules of copper and gold or copper and silver,respectively. I n the lead-rich lead-antimoay alloys the existenceof the compound Pb,Sb dissolved in monatomic lead is indicated.The liquid and solid solution phases of copper-magnesium alloysconsist of simple atoms of copper and magnesium; the existence ofMgCu, and Mg,Cu is also confirmed by the thermodynamical method.The thermodynamics of solid-solution alloys has also been treatedby C.Wagner and W. Schottky 40 and by H. S e l t ~ . ~ lAlloys of the Alkali and Alkaline-earth Netnls.-The sodium-potassium equilibrium has been investigated under conditions ofmanipulation that exclude contact with air.42 An unstable com-pound Na,K and a eutectic containing 66 atoms yo of potassiumhave been confirmed. Viscosity determinations of these alloys inthe liquid phase a t 125" show a maximum at the composition&Na, but giveThe solidification diagram of the sodium-rubidium system doesinflexion to indicate the compound Na2K.4340 2.phyaikat. Chem., 1930, [BJ, 11, 163; A., 1931, 157.4 1 J . Amer. Chem. SOC., 1934, 56, 307; A., 1934, 366.42 E. Rinck, Compt. rend., 1933, 19'7, 49; A., 1933, 771.43 R. Kremann, M. Pestomer, and H. Schreiner, Rec. trav. clzirn., 1932, 51,557 ; A., 1932, 800172 INORGANIC CHEMISTRY.not resemble that of the sodium-potassium alloys, and no evidenceof the compound NazRb was found.44 A eutectic occurs a t 75atoms yo of rubidium at - 4.5". The curve tends to becomehorizontal in the vicinity of the composition corresponding withNaRb,. In the sodium-caesium system thermal analysis shows anew compound Na2Cs, and a eutectic at 75 atoms yo of caesium and- 30°.45 The mutual solubilities of sodium and calcium have beendetermined.46 Potassium and rubidium are completely misciblein the solid state; the liquidus and solidus are very close andshow a flat minimum at 32-8", corresponding with 66.6 atoms yo ofrubidium.The system calcium-bismuth forms two compounds, Ca,Bi, andCaBi,.The alloys of this system are attacked by moist air.48Alloys of calcium with smaller amounts of zinc, aluminium, ormagnesium have been prepared as greyish-white powders, which arereadily attacked by exposure to air and moisture.49 The calcium-gold system contains 6 compounds : Au,Ca, Au2Ca, AugCal0, Au,Ca,Au3Ca4, and AuCa2. Calcium is practically insoluble in solid gold,but at room temperature it dissolves 4-5 atoms yo of g0ld.~0The lithium-silver alloys have been examined for the first time,the X-ray method being used.At 500" the metals react violmtlywith evolution of heat. The existence of the compounds AgLi andAgLi, has been established. Since no alteration in the lithium orsilver lattices was observed, it is concluded that solid solutions arenot formed. 51 Similar experiments, coupled with thermal analysis,on the lithium-copper alloys give a, quite different result, for nocompounds or solid solutions are formed.52 Thermal analysis andelectrical-resistance measurements of lithium-cadmium alloys haveconfirmed the existence of LiCd and proved the existence of thehitherto unknown compounds LiCd, and Li,Cd.53 The compoundsLiCd and LiCd, have been confirmed independently by X-rayanalysis,54 but Li,Cd was not detected by this method. The com-pounds LiTl, Li,Tl, Li5T12, Li3T1, and Li,T1 have been detected by44 E.Rinck, Compt. rend., 1933, 197, 1404; A., 1934, 137.45 Ibid., 1934, 199, 1217; A., 1935, 22.4 6 Ibid., 1931,192, 1378; A., 1931, 900.4 7 Ibid., 1935, 200, 1205; A., 693.48 E. Kurzniec, Bull. Acad. polowise, 1931, [ A ] , 31; A., 1931, 1118.49 J. MeyerandR. Goralczyk, 8. angew. Chem., 1930,43,149; B., 1930, 330.F. Weibke and W. Bartels, 2. anorg. Chern., 1934,218,241 ; A., 1934, 838.51 S. Pastorello, Gaxxetta, 1930,60,493; 1931,61,47; A., 1930, 1359; 1931,sa Ibid., 1930, 60, 988; A., 1931, 296.53 G. Grube, H. Vosskiihler, and H. Vogt, 2. Elektrochem., 1932, 38, 869;54 A. Baroni, Atti R. Acmd. Lincei, 1933, [vi], 18, 41; A,, 1934, 137.418.A,, 1933, 18HEDGES : NON-FERROUS ALLOY SYSTEMS.173thermal analysis and electrical-resistance determinations. 55 Ofthese, Li5T1, and Li,Tl can be melted without decomposing. Similarmethods applied to alloys of lithiurn and bismuth show the existenceof Li,Bi and LiBi; 56 the latter is dimorphous.Copper AZZoys.-Certain aspects of the copper-gold alloys havereceived much attention. The transformation of the alloy con-taining 50 atoms % of each metal, from the cubic face-centredlattice with irregular distribution of atoms to the tetragonal latticewith regular distribution, has been studied by X-ray analysis.57With falling temperature the transformation occurs in two steps :(1) change of the lattice symmetry from cubic to tetragonal,(2) transition from an irregular to a regular distribution of theatoms.The first step occurs rapidly and completely, the secondslowly and incompletely. Thus an intermediate state is reached,which is characterised by a considerably increased hardness, tensilestrength, and electrical resistance. 58 In this system the existenceof AuCu and AuCu, has been confirmed.59 A transformation inAuCu, has been studied.60 In addition to the AuCu and theAuh, transformation, J. L. Haughton and R. J. M. Payne 61 havefound another transformation in alloys approximating to thecomposition of Au,Cu,. The conipound Au2Cu, is also indicatedby the electrical conductivity and thermoelectric force curves ofM. Le Blanc and G. Wehner,62 but is denied by W.Broniewski andK. Wesolowski. 63W. R. D. Jones 6* obtained evidence of Mg,Cu and MgCu,, butnot of MgCu. In spite of the old-established use of brasses, theequilibrium diagram of the copper-zinc alloys has not been un-equivocally settled. Examination of numerous properties of awide range of these alloys 65 has confirmed the existence of thecompounds CuZn, CuZn,, and CuZn,, but not Cu,Zn,, Cu,Zn,55 G. Grube and G. Schrtufler, 2. Elektrochem., 1934,40,593 ; A., 1934,1065.5 6 G. Grube, H. VosskiLhler, and H. Schlecht, ibid., p. 270; A57 K. Oshima and G. Sachs, 2. Physib, 1930,63,210; U. Dehlinger and L.Graf, ibid., 1930, 64, 359; A., 1930, 1360; L. Graf, 2. Metallic., 1932, 24, 248;A., 1932, 1196.1934, 724.68 E. Schucb, Metallwirt., 1933, 12, 145; A., 1933, 1238.50 N.S. Kurnakow and N. W. Ageew, J . Inst. Metals, 1931, 46, 481; A . ,60 G. Sachs and J. Weerts, 2. Physik, 1931, 67, 507; A., 1931, 414.61 J . Inst. Metals, 1931, 46, 457; A., 1931, 1224.62 Ann. Physib, 1932, [v], 14, 481 ; A., 1932, 989.63 Compt. rend., 1934, 198, 370; A,, 1934, 248.84 J . Imt. Metals, 1931, 46, 396; A., 1931, 1224.65 W. Broniewski and J. Strasburger, Compt. rend., 1930, 190, 1412; Rev.Aldt., 1931, 28, 19, 70; Pram Zakladu Metall. Pol. Warsaw, 1933, 3, 3; A .1930, 987.1932, 1224174 MOEGANIC CHEMISTRY.Cu1,Zn13, Cu21Zn31, Cu3Zn,, Cu,Zng, or Cu,Zn. On the other hand,C. Rossi 66 claims to have prepared single crystals of cU,Zn3. Thecrystal structures of Cu5Zn8 and Cu,Cd, have been ~ompared.~’The relation between mean atomic volume and composition in thisseries of alloys has been studied.68 Examination of the electricalproperties of the copper-cadmium alloys suggests the existence ofCuCd,, CuZCds, Cu,Cd,, and possibly Cu,Cd.The copper-gallium system has been investigated; 69 it contains7 intermediate phases, including Cu,Ga and CugGa,.The copper-indium system is somewhat similar 70 and contains the compounds&,In, CuJn,, and Cu21n.Further evidencethat the &phase is Cu,,Sn8, not Cu,Sn, has been obtained,72 whilstthe &-phase, formerly written as CuSn, is confirmed as c ~ , S n , . ~ ~It has also been shown that an alloy, identical with Cu,Sn preparedby fusion, is produced by the action of tin on copper sulphatesolutions under certain conditions.74 Equilibria in the ternarysystems of copper and tin with ni~ke1,7~ manganese,V6 lead,77 orberyllium 78 have been investigated.Xilver AZZoys.-X-Ray analysis has confirmed the existence ofAgCa and Ag,Ca, but not of Ag4Ca, Ag,Ca, or AgCa,, formerlyclaimed.79 By the thermal method, the existence of Ag4Sr, Ag5Sr,,AgSr, and Ag,Sr3 and also of Ag,Ba, Ag3Ba2, and Ag,Ba, isindicated. *OThe lattice parameters and densities of solid solutions of aluminiumWork continues on the copper-tin series.716 6 2;. Physsib, 1932, ‘74, 707; A., 1932, 454.6 7 A. J. Bradley and C. H. Gregory, Phil. Mag., 1931, [vii], 12, 143; A.,68 E. A. Owen and L. Pickup, Proc. Roy. SOC., 1933, [A], 140, 179; A.,69 F. Weibke, 2. anorg. Chem., 1934, 220,293; A., 1935,22.7 O F.Weibke and H. Eggers, ibid., p. 273; A., 1935, 22.7 1 J. Vero, 2. anorg. Chem., 1934,218, 402; A., 1934, 953.72 M. Hamasumi and S. Nishigori, Tech. Rep. Tdhoku, 1931, 10, 131: A . ,73 M. Hamasumi, Kinz. no Kenk., 1933, 10, 137.74 H. Kersten and J. Maas, J . Amer. Chem. SOC., 1933, 55, l.002; A., 1933,454.75 J. T. Eash and C. Upthegrove, Trans. Amer. Inst. Min. Met. Eng., 1933,104,221; A., 1933, 119; J. Vera, Mitt. Berg. Hutten. Abt. Hochschule, Sopron,1932, 4, 1.1931, 896.1933, 454.1931, 900.7 6 Idem, ibid., 1933, 5, 1 ; A., 1934, 1301.7 7 Idem, ibid., 1932, 4, 1.7 8 E. S. Rowland and C. Upthegrove, Amer. Tnst. Min. Met. Eng., 1935,79 C. DBgard, 2. Krist., 1935, 90, 399; A., 1198.80 F. Weibke, 2. anorg.Chem., 1930,193,297; A., 1930, 1509.Tech. Publ. No. 613; A , , 1935, 1066HEDGES : NON-FERROUS ALLOY SYSTEMS. 175in silver have been measured.81 The experimental densities areslightly lower than those calculated on the basis of a direct sub-stitution of aluminium for silver a.tioms in the silver lattice, and it isconcluded that the aluminium in the solid solution must be com-bined chemically with the adjacent silver. Re-examination of thissystem by thermal analysis 82 shows three compounds : Ag,Al,Ag3Al2, and Ag,A1.83 The solid solubility of indium in silver is19.4% at room temperature. The system contains the compoundsAg,In, AgJn,, and AgIn,.84 The system silver-praseodymiumcontains Ag,Pr, Ag,Pr, and AgFr.*5 The ternary systems of silverand zinc with copper or aluminium,86 and of silver and antimonywith zinc, cadmium, or copper 87 have been investigated, andsimilar types of alloys have been examined from the viewpoint ofan improved, untarnishable sterling silver.88Magnesium Alloys.-A new diagram for the magnesium-zincalloys89 shows the compounds MgZn,, MgZn,, and MgZn.X-Ray investigation of magnesium-cadmium alloys containing30-80 atoms yo of magnesium has confirmed the existence ofMgCd, and Mg,Cd, but not MgCd,.90 The equilibrium diagram ofthe magnesium-thallium system has been re~ised.~l Earlier inves-tigations had suggested the existence of the compounds T13Mg8 ,TlMg,, and T12Mg,.Of these only TlMg, has been confirmed, theothers appearing to be eutectics. I n addition, T1,Mg5 and TlMgare considered to exist.The alloys with praseodymium includetwo well-gefined compounds, MgPr and Mg,Pr, and probablyMgPr,.92 Electrical-conductivity measurements of magnesium-richalloys with tin show a minimum at the composition corresponding81 R. T. Phelps and W. P. Davey, Asner. Inst. Min. Met. Eng., 1931, Tech.82 F. E. Tischtckenko, Zhur. Obs. Khim., 1933, 3, 549; A., 1934, 21.83 Cf. N. Ageew and D. Shoyket, J . Inst. Metals, 1933, 52, 119; A., 1933,84 F. Weibko and H. Eggers, 2. anory. Chem., 1935, 222, 145; A., 576.as G. Canneri, Met. Ital., 1934, 26, 794.86 S. Ueno, Mern. Coll. Sci. Kyat6 Imp. Univ., 1929, 12, 347; 1930, 13, 91 ;A., 1930, 284, 535.87 W. Guertler and W. Rosenthal, Z. Metallk., 1932, 24, 7, 30; A., 1932,455.88 K.W. Ray and W. N. Baker, Ind. Eng. Chem., 1932, 24, 778; B., 1932,845; L. Guillet, A. Petit, and J. Cournot, Rev. Mkt., 1932, 29, 113, 183; B.,1933, 393.89 A. A. Botschvar and I. P. Velitschko, 2. anorg. Chem., 1933, 210, 164;A., 1933, 219.90 U. Dehlinger, ibid., 1930,194, 223; A., 1931, 167.9 1 G. Grube and J. Hille, 2. Elektrochem., 1934,40,101; A , , 1934, 356.92 G. Canneri, Met. Itat., 1933, 25, 250; A., 1934, 483.Publ. No. 443, 1.1110176 INORGANIC CHEMISTEY.with Mg,Sn.93 The magnesium-antimony system contains onlyone compound Mg,Sb,, which is dimorphous, having a transforma-Lion temperature a t 930" & 2O.94 The solid solubility of nickel inmagnesium is less than O*l% .95 Ternary systems investigatedinclude magnesium-aluminium-copper,g6 magnesium-zinc-silicon,97and magnesium-zinc-calcium.98Mercury AZZoys.-E&dence that dilute liquid amalgams arecolloidal sols in which mercury acts as dispersion medium has beenobtained in amalgams of sodium,99 copper and silver,l and iron.2Thermal analysis of the rubidium-mercury system indicates thecompounds Rb,Hg,, RbHg,, Rb2Hg,, Rb5Hgls, Rb,Hgg, RbHg,,RbHg,, and Rb,Hg,.3 Comparison with other mercury-alkali metalsystems shows that the affinity for mercury increases as the atomicweight of the alkali metal increases, and the compounds formedare more complex.The constitution of silver amalgams has beendetermined ; 4 X-ray investigation shows the presence of Ag,Hg,.5The compounds Li,Hg, Li,Hg, Li2Hg, LiHg, LiHg,, and LiHg,have been detected in lithium amalgams by thermal analysisand confirmed by x-ray^.^ Only Li,Hg and LiHg can be meltedunchanged.Although thermal analysis and microscopical examina-tion have given PO evidence of compound formation in cadmiumamalgams, X-ray analysis indicates that Cd,Hg exists.*Determinations of the parachor of thallium dissolved in mercuryshow that it is not in the monatomic state, but is combined withmercury or other thallium atoms t o form polyatomic molecu1es.gThe solid thallium amalgams have been examined by ihe X-ray93 G. Grube and H. Vosskuhler, 2. Elektrochem., 1934, 40, 566; A., 1934,1065.9 p G. Grube and R. Bornhak, ibid., 1934,40, 140 ; A., 1934, 590.Ofr J. L. Haughton and R. J. M. Payne, J .Inst. Metals, 1934, 54, 275; A . ,1934, 590.9 6 A. Portevin and P. Bastien, Compt. rend., 1932, 195, 441 ; A., 1932, 989;Ghim. et I n d . , 1934, Special No., 490; A., 1934, 725.9 7 E. Elchardusand P. Laffitte, Compt. rend., 1933,197,1125; A., 1934,23.98 R. Paris, ibid., 1933, 197, 1634; A., 1934, 138.99 G. R. Paranjpe and R. M. Joshi, J . Physical Chem., 1932, 36, 2474; A . ,1932,1196; H. E. Bent, ibid., 1933,37,431; A., 1933, 561.R. Kijhler, Kolloid-Z., 1933, 64, 200; A., 1933, 895.N. M. Tchuiko, Ukrain. Chem. J., 1931, 6, 229.W. Biltz, F. Weibke, and H. Eggers, 2. anorg. Chem., 1934,219,119; ,4.A. J. Murphy, J . Inst. Metals, 1931, 46, 507; A , , 1931, 1224.G . Grube and W. Wolf, 2. Elektrochem., 1935,41,675; A., 1314.N. W. Taylor, J .Amer. Chem. SOC., 1932, 54,2713; A , , 1932, 989.1934, 1064.j A. Weryha, 2. Krist., 1933, 86, 335; A., 1934, 16.'J E. Zintl and A. Schneider, ibid., 1935, 41, 771.9 L. Belladen and A. Triolo, Gazzetta, 1934, 64, 461HEDGES : NON-FERROUS ALLOY SYSTEMS. 177metliod.10 There is evidence that many rare-earth metal8 formcompounds with mercury of the type MHg4.11The solubility of iron in mercury at 20" is 0.00007% ; and thatof nickel 0.00014% (by wt.).12 The solubility of gold in mercuryat 280-400° has been determined ; the gold-rich compound isprobably A~~Hg.13 An X-ray investigation of alloys of mercurywith gold, silver, or tin has been carried 0 ~ t . 1 4 The system mercury-manganese-tin has been studied.15A considerable number of binary, ternary, and quaternary com-pounds of metals such as copper, tin, zinc, and iron with or wibhoutmercury have been obtained by A.R. Russell and his collaborators l6by reaction in mercury.A technique for determining the vapour pressure of amalgamshas been described and applied to amalgams of the alkali meta1s.l'AZuminium Alloys.-Much of the work on aluminium alloys con-cerns their properties for structural purposes and is of interestmainly to metallurgists and engineers. A summary of availableinformation on the constitution of binary alloys of aluminium hasbeen given by E. T. Richards.lsThe solubility of sodium in molten aluminium has been determined ;there is no evidence of solid solubility,lQ nor has a solid solubilityof barium in aluminium been detected.20 X-Ray examination hasestablished one compound A1,Ba in the aluminium-barium system.21The solid solubilities of beryllium 22 and magnesium 23 in alumin-ium have been determined.An investigation of the aluminium-magnesium alloys shows that the two metals are mutually solublein the solid state and can form the compounds AI,Mg,, AlMg, andA13Mg4.24 G. Wassermann 25 has shown that the lattice parameterlo A. Olander, 2. phyeikal. Chem., 1934, [ A ] , 171,425; A., 1935,440.l1 P. T. Daniltchenko, Zhur. Obs.Khinh., 1931, [ A ] , 163,467; A., 1931, 1381.l2 E. Palmaer, Z . Elektrochem., 1932, 38, 70; A , , 1932, 330.l4 S. Stenbeck, Z. anorg. Chem., 1933, 214, 17; A., 1933, 1006.l5 A. N. Campbell and H. G. Carter, Trana. Paraday Soc., 1933, 29, 1295 ;A., 1934, 138.l6 Nature, 1930, 125, 89; 1934, 133, 217; J., 1932, 841, 852, 857; 1934,1750; A., 1930, 177; 1932, 456, 1083; L934, 265.1 7 J.S. Pedder and S. Barratt, J., 1!)33, 537; A., 1933, 669; H. H. vonHalban, jun., Helv. Phyaica Acta, 1935, 8, 65.la Metallb6rae, 1935, 25, 498, 530, 562, 721, 1041.l9 E. Scheuer, 2. Metallk., 1935, 27, 83; A., 928.2o E. Alberti, ibid., 1934, 26, 6; A . , 1034, 482.21 K. R. Andreas and E. Alberti, ibid., 1935, 27, 126 ; A., 1065.22 M. Haaa and D. Uno, ibid., 1930, 22,277; B., 1930, 1072.23 E. Schrnid and G. Siebel, ibid., 1931, 23, 202; B., 1931, 978.24 M. Kawakami, Kinzoku no Kenkyu, 1933,10,532.25 Z . Metalllc., 1930, 22, 158; B., 1930, 717.J. T. Anderson, J . Physical Chem., 1932,36,2145178 NORUANIC CHEMISTRY.of aluminium is increased by about 0-0045 fi.for every 1 atom yoof magnesium added, and by about 0.001 A. for every 1 atom %of zinc. Purther X-ray work indicates that the supposed compoundA12Zn, does not exist.26N. A. Pushin and V. Staji627 claim to have detected the com-pounds A12Ga, AlGa, and AlGa,, but this claim is not substantiatedby the experiments of E. Jenckel.28 In the system aluminium-praseodymium29 the compounds PrAl, PrAl,, and PrAl, are saidto exist, the last in two modifications. A revision of the diagramfor aluminium-rich aluminium-titanium alloys has been under-taken, and the compound TiAl, confirmed.30 It has been shown 31that variations in casting temperature and rate of cooling determinewhether the TiAl, in these alloys separates out as needles or remainsso highly dispersed that the alloy behaves as a solid solution.The solid solubility of antimony in aluminium is less than 0*1% ; 32only one compound, AlSb, is formed in this system.The compounddecomposes in moist air.33Dissolution in dilute hydrochloric acid of an aluminium alloycontaining 1 4 % of chromium leaves a residue of rhombohedra1plates of CrA4.34 In the aluminium-manganese system, A. J.Bradley and P. Jones 35 detected by X-rays the compounds Al,Mnand A1,Mn. Since small amounts of iron profoundly affect theequilibria, this system has been re-examined, metals of very highpurity being used.36 The solid solubility of manganese in aluminiumwas determined, and the existence of Al,Mn and Al,Mn established.An investigation of the system aluminium-cobalt 37 shows that thesolid solubility of cobalt in aluminium is very small.A eutectic at1.45% of cobalt was observed. When the sluminium-rich alloys2e E. Schmid and G. Wassermann, 2. Metullk., 1934, 26, 146; A., 1934,1064.2 7 Z. anorg. Chern., 1933, 216, 26; A., 1934, 138.28 Z. Metalllc., 1934, 26, 249.29 G. Canneri, Alluminio, 1933, 2, 87.30 W. L. Fink, K. R. van Horn, and P. M. Budge, Amer. Inst. Min. Met. Eng.,31 H. Bohner, 2. MetallE., 1934, 26, 268.32 E. H. Dix, jun., F. Keller, and L. A, Willey, Amer. I n s t . Min. Met. Zng.,33 J. Veszelka, Mitt. Berg. Hiitten. Abt. Hochschule, Sopron, 1931, 3, 193;34 W. L. Fink and H. R. Freche, Trans. Amer. Imt.Min. Met. Eng., Inst.35 Phil. Mag., 1931, [vii], 12, 1137; A., 1932, 116.36 E. H. Dix, jun., W. L. Fink, and L. A. Willey, Trans. Amer. I n s t . Min.37 W. L. Fink and H. R. Freche, Amer. Inst. Min. Met. Eng., 1932, Tech.1931, Tech. Publ. No. 393, 1; A . , 1931, 676.1930, Tech. Publ. No. 356, 1; A., 1931, 158.A . , 1932, 1082.Metals Div., 1933, 104, 325.Met. Eng., Inst. Metals Div., 1933, 104, 335.Publ. No. 473, 1 ; A., 1932, 683HEDGES NON-FERROTTS ALLOY SYSTEMS. 179are treated with dilute acids, a residue having the formula Co,Al,is obtained.Ternary systems, the constitutioiis of which have been inves-tigated, include aluminium-magnesium-silicon,3~ aluminium-copper-~ilicon,~~ aluminium-iron-silicon,40 aluminiurn-antimony-rn~gnesium,~l aluminium-silver-rnagnesiumY*2 and aluminium-ni~kel-tin.~~Tin AZZoys.-The equilibrium diagrams of all the known binaryalloys of tin have been compiled and annotated by E.S. Wedgesand C. E. Homer.44 X-Ray analysis of the tin-gold system con-firms the existence of AuSn, AuSn,, and A U S ~ , . ~ ~ Thermalinvestigation of tin-lithium alloys indicates the existence of SnLi,,Sn,Li,, and Sn,Li; X-ray analysis confirms the first two, but notthe last .46 Other thermal and electrical conductivity measure-ments in this system demonstrate the compounds SnLi,, Sn,Li,,Sn,Li,, SnLi2, SnLi, and Sn,Li. The solid solubility of lithium intin is inappre~iable.~' Tin-barium alloys have been prepared byelectrolysis of eutectic mixtures of barium and potassium chlorideswith a molten tin cathode.48 The system contains the compoundsSn,Ba and Sn5Ba. Tin-strontium alloys have been prepared by asimilar method, and the compounds Sn,Sr and Sn,SrThe tin-arsenic alloys have been investigated by X-rays.50There is a wide range of solid solubility at both ends of the series;the compound SnAs exists, but not Sn,As,. Several X-ray investi-gations of the tin-antimony system have been made.51 The38 L. Losana, Met. Ital., 1931, 23, 375; A., 1932, 907; E. H. Dix, jun., F.Keller, and R. W. Graham, Amer. Inst. Min. Met, Eng., 1930, Tech. Publ. No.357, 1 ; A., 1931, 158.39 G. G. Urazov, S. 9. Pogodin, and G. M. Zomornev, illin. Syrie i Zvet.Metally, 1929, 4, 160.40 V. Fuss, 2. Metallk., 1931, 23, 231 ; B., 1931, 929.41 E. Loofs-Rassow, Hausxeit. V.A.1V.u.d. Eqtwerk A.G. Alunvinium, 1031,42 B. Otani, Kinxoku no Kenkyu, 1933,10, 262.43 S. Kato, Suiyokai-Shi, 1931, 6, 529 ; A., 1932, 567.44 Internat. Tin Res. and Dev. Council, 1935, Tech. Publ. B., No. 2, 1-90;45 S. Stenbeck and A. Westgren, 2. physikal. Chem., 1931, [B], 14, 91 ; A . ,413 A. Baroni, Atti R. Accad. Lincei, 1932, [vi], 16, 153; A., 1933, 18.4' G. Grube and E. Meyer, Z. Elektrochem., 1934, 40, 771 ; A., 1935, 23.48 K. W. Ray, Metals and Alloys, 1930, 1, 314; A., 1930, 681.50 W. H. Willott and E. J. Evans, Phil. Mag., 1934, [vii], 18, 114; A.,1934, 953.51 W. M. Jones and E. G. Bowen, Nature, 1930,126, 840; Phil. Maya., 1931,[vii], 12, 441; A., 1931, 33; K. IwasB, N. Aoki, and A. osawa, Sci. Rep.Tdhoku Imp. Univ., 1931, 20, 353; A., 1931, 1364.3,20; B., 1931, 1143.A., 1065.1931, 1223.Idem, I n d . Eng. Chem., 1930, 22, 519; B., 1930, 866180 INORGANIC CHEMISTRY.compound formed is definitely SnSb, not Sn,Sb,. Single crystalsof this compound have been obtained.52 The tin-bismuth systemhas been examined by the X-ray method.53 A marked effect ofbismuth in reflning the grain size of tin has been noted.54The solid solubility of silver, copper, or nickel in tin is very ~mall.~5No intermetallic compound has been found in the tin-cadmiumsystem. 56Re-examination of the tin-iron system 57 gives no evidence ofFe,Sn, but shows the compounds Fe,Sn, FeSn, and FeSn,. Thesecompounds have been confirmed independently by W. F. Ehret andA. F. Westgren 58 and by W. D. Jones and W. E. H ~ a r e . ~ ~ FeSn,,but no other tin-iron compound, occurs in tin-plate.60Lead AZloys.-With calcium, the compounds Pb3Ca and PbCaare formed.61 A complete equilibrium diagram for the lead-lithiumsystem has been established ; the compounds PbLi, Pb,Li,, PbLi,,Pb,Li,, and PbLi, are formed.62Lead and germanium do not form solid solutions or compound^.^^No compound of lead with arsenic is formed, and the solid solubilityof arsenic in lead is only about 0.01% a t room temperat~re.~~There is no evidence for the formation of a solid solution of antimonyin lead, or of any definite compound in the series.65An outstanding achievement in lead alloys is the improvementof mechanical properties and corrosion resistance of lead by theaddition of a small amount of tellurium.66 E. S. H.S. R. CARTER.E. S. HEDGES.W. WARDLAW.G2 H. S. van Klooster and M. 0. Debacher, Metals and Alloys, 1933, 4, 23 ;A., 1933, 344.53 D. Solomon and W. M. Jones, Phil. Mag., 1931, [vii], 11, 1090; A., 1931,676.54 A. A. Botchvar and N. E. Merkurjew, 2. anorg. C'hem., 1933, 210, 161 ;d., 1933, 219; D. Hanson and E. J. Sandford, J . Inst. Metals, 1935, 56, 191.55 D. Hanson, E. J. Sandford, and H. Stevens, ibid., 1935, 55, 115.5 6 D. Hanson and W. T. Pell-Walpole, ibid., 1935, 56, 165 ; A., 1936, 440.57 C. A. Edwards and A. Preece, J . Iron Steel Inst., 1931, 124, 41; B.,58 J . Arner. Chern. Soc., 1933,55, 1339; A., 1933, 562.59 J . lron Steel Inst., 1934, 129, 273 ; A., 1934, 724.6o W. E. Hoare, ibid., 1934, 129, 253; B., 1934, 581.61 R. R. Syromiatnikov, Metullurg., 1931, 6, 466.62 G. Grube and H. Klaiber, 2. EZektroch,ern., 1934, 40, 745.63 T. R. Briggs and W. S. Benedict, J . Physical Chem., 1930, 34, 173; A.,64 0. Bauer and W. Tonn, 2. Metallk., 1935, 27, 183.65 D. Solomonand W. M. Jones, Phil. Mug.,1930, [vii], 10,470 ; A., 1930,1359.6 6 W. Singleton and B. Jones, J . Inst. Metals, 1933,51, 71 ; B., 1933, 351.1931, 1053.1930, 284

ISSN:0365-6217    

DOI:10.1039/AR9353200138

出版商:RSC    

年代:1935

数据来源: RSC

摘要:

CRYSTALLOGRAPHY.(1934-1935.)CRYSTAL PHYSICS.The Electron Theory of Metals.--Tt has long been known that thecharacteristic structure of certain alloys is determined not so muchby its composition as by the ratio of the total number of valencyelectrons t o the total number of atoms in the unit cell. Thus, thecharacteristic complex structure of y-brass is shared by the alloysCu5Zn8, Cug& Cu,Sn8, Ni5Zn21, and many others which all have incommon an electron : atom ratio of 21. : 13. Similarly, the structureof p-brass corresponds to an electron : atom ratio of 3 : 2, and thatof &-brass to a ratio of 7 : 4. These ratios, first put forward onempirical grounds by Hume-Rothery in 1927, have recently beengiven a quantum-mechanical explanation by H. J0nes.l An attemptis here made to give an elementary physical picture which willconvey the essential features of the theory.The state of an electron may be completely defined in terms ofthe three co-ordinates kz, E,, and E, of its momentum.If weimagine these co-ordinates to be plotted along three rectangularaxes, the state of the electron is described by the point (kx, k,, kz)in the momentum space thus defined. If the electron is free, theenergy associated with the state is proportional to the square ofthe momentum, i e . , to the square of the vector joining the point inquestion to the origin of momentum space. On account of thequantum conditions and the exclusion principle, no two electronsmay exist in the same state, so that each electron requires foritself a definite volume of momentum space, and an assemblage ofmany electrons will occupy a spherical domain whose size is deter-mined by the number of electrons considered.If the electrons arenot free, as will be the case in a crystal where we must take intoaccount the effect of the lattice field, it can be shown that the energyof the electron no longer varies continuously with the momentum,but that there are certain planes in momentum space such thatwhen the point describing the state of the electron crosses one ofthese planes a discontinuous energy change takes place.2 Theelectrons in the neighbourhood of a discontinuity are those whose1 Proc. Roy. Soc., 1934, [A], 144, 225 ; A., 1934, 483.2 Brillouin, “ Quantenstatktik,” Chap.8; A. Sommerfeld and H. A.Bethe, “ Handbuch der Physik,” XXIV, 2182 CRYSTALLOGRAPHY.wave-length and direction would lead them to be reflected by thecorresponding plane of the crystal. Just below the plane theenergy is abnormally depressed ; just above ib, abnormally raised.Between successive planes the energy varies continuously withmomentum and approximates to that of a free electron, It niaybe shown, further, that the planes in momentum space acrosswhich these energy discontinuities take place are parallel to allpossible crystallographic planes in the crystal, so that in the case ofe.g., a cubic substance, the origin is surrounded by a series ofconcentric zones successively bounded by the faces 01 the cube, thedodecahedron, the octahedron, and so on.The magnitude of theenergy jump across the various zones is not constant, but is pro-portional to the degree of scattering of electron waves from thecorresponding plane in the crystal, and therefore closely relatedto the intensity of the X-ray reflexion : if all the atoms in thestructure have nearly the same atomic number, it is actuallyproportional to the amplitude of this reflexion.In the y-alloys, experiment shows that, of the planes with smallindices, only those of the forms (411) and (330) give rise t o strongX-ray reflexion. We therefore conclude that the first planes inmomentum space outwards from the origin across which the energyshows an appreciable discontinuity are those lying parallel t o facesof these two forms.The figure bounded by these two forms is apolyhedron of 36 faces, not very far from spherical in shape.Let us now imagine that the number of electrons in the structureis gradually increased from zero. At first, the Fermi distribution,i.e., the volume occupied by the states oi the electrons in momentumspace, will grow very nearly spherically until it comes into proximitywith the faces of the zonal polyhedron. When the sphere touchesthe zone, the distribution will no longer grow in that particulardirection, since to do so would correspond to a large energy incre-ment, but rather in other directions in which growth can still takeplace without the zone being crossed. The distribution will there-fore ultimately assume a distorted shape approximating to that ofthe zone. Jones has calculated that in the case of the y-alloys, fora unit cell containing 62 atoms, the spherical Fermi distributioninscribed in the zoiial polyhedron corresponds to 80 electrons,whereas the whole polyhedron would hold 90.The actual numberof electrons in the unit cell is 84, so that in the y-alloys the surfaceof the Fermi distribution lies very close to the surface of energydiscontinuity. This Jones states to be the distinguishing featureof the ?-structures. The exact filling of the zone corresponds tolowering of the energy of the lattice relative to other lattices with adifferent zone arrangement, and consequently adds stability to thBERNAL : CRYSTAL PHYSICS. 183structure. In terms of the theory of diamagnetic susceptibilitygiven by R. Peierls,3 it accounts for the remarkably large diarnagneticsusceptibilities of the y-alloys, and it also gives an explanation ofthe large Hall coefficient which tliese alloys show.H.Jones4 has now extended the theory to the case of E- andq-phases, and has succeeded in accounting for the observed variationof the axial ratio with composition in these phases and also for therange of composition over which the phase is stable. In thesecases, and also in the case of bismuth, there is a very small butfinite ‘ overlap ’ of the Fermi distribution beyond the first Brillouinzone. From this, the diamagnetic susceptibilities of bismuth andsome of its alloys, and also the magnetostriction, are deduced ingood agreement with experiment.The application of the theory t o the p-phase has been consideredby U.Dehlinger,5 who shows that in this case the first zone is onlypartially filled, since the number of electrons which it would accom-modate is two per atom whereas the observed electron : atomratio is 3 : 2. This, according t o Dehlinger, corresponds to thefact that p-phases are stable only at high temperatures.As the result of these theoretical advances, we are now in a,position t o get a general view of metal chemistry and its relationto the other parts of chemistry. Such a picture has been givenby F. Hund.6 In it, electrons are pictured as occupying bondingand anti-bonding states. If each atom brings so few electrons thatonly part of the former are filled, the result is a metal of the generalA type of alkalis and alkaline earths.When the bonding zone isexactly filled, the result is an insulator of the type of diamond.If part of the next anti-bonding zone is filled, the result will beagain a metal, but of the B type of bismuth or tellurium (theelectrons of course can be used to form a closed shell molecule asin red selenium, Ses, or yellow phosphorus, P4). Finally, if bothzones are filled, the result is again an insulator, this time a rare gas.E. Wignerand F. Seitz 7 and J. C. Slater 8 have calculated the energies andlattice constants of sodium and lithium on the basis of free electronbinding.With the adamantine class and the B-group metals, it isimpossible to go so far. Clearly, here a considerable part of thelattice energy is derived from the degree of filling of the BrillouinThe theory of the A type metals is fairly satisfactory.2.Physik, 1933, 80, 763.4 Proc. Roy. Soc., 1934, [A], 147, 396; A., 1935, 153.5 %. Phystk, 1935, 94, 231 ; Metallwirt., 1935, 14, 145.7 Physical Rev., 1933,43,804; 1934,46,509, 1102; 1935,47,400.* Ibid., 1934, 45, 794; Rev. Mod. Physics, 1934, 6, 209.‘‘ The Solid State of Matter,” Phys. SOC, Rep., 1935, p. 36184 CRYSTALLOGRAPHY.zones as in the Jones theory. The corresponding calculatioiishave been done for the diamond 9 with qualitatively satisfactoryresults, although no theory has its yet served to explain the veryremarkable optical and photoelectric properties of diamonds which,as (Sir) R.Robertson, J. J. Pox, and A. E. Martin lo have shown,differentiate them into two widely different types.The adamantine compounds can, however, also be formulated asmacro-molecules with shared electron orbitals. They mark theboundary between the explanation of crystal structures by metallicor by homopolar conceptions.The structure of the transition metals offers more theoreticaldifficulties because here the core as well as the free electrons has tobe taken into account. K. Fuchs l1 has calculated the equilibriumcopper lattice with fair success.The magnetic and electrical properties of the transition metalsand of some of their alloys, particularly those of nickel, have beendiscussed from a somewhat different point of view by N. F.Mott.12In the case of the transition metals partially filled d levels exist, andthe extra electrons contributed by other atoms in the alloy can goto fill up these levels. U. Dehlinger 13 from structure considerationsconcludes that all the transition metals except iron contain onlyone s electron. We are, however, far from having as yet an adequatetheory of the transition metals.Order-Disorder Transformations in Alloys.-Where two metalsare alloyed together, a series of solid phases is in general formed.The composition of each phase can be varied continuously over acertain range, within which the alloy remains homogeneous, andwhich generally includes a composition of relatively simple atomicproportions. We may therefore regard each phase as having someideal composition, departures from which can take place withoutthe appearance of a new phase by the statistical replacement ofsome atoms of one constituent by atoms of the other.Thus, totake a concrete example, in the system Au-Cu two of the phaseshave the ideal compositions CuAu and Cu,Au. When we investigatethe structure of such a phase, we find in general that in a properlyannealed specimen the two types of atom assume definite relativepositions in the structure. In the phase Cu,Au, the gold atoms arefound at the corners of a simple cubic unit cell, the copper atomsoccupying the centres of the faces. Such a structure is termed aW. F. Laschkarev and A. 8. Tschabau, Physikal. 2. Sovietunion, 1935, 8,240 ; Kimball, J . Chem. Physics, 1935, 3, 560 ; Nath, Proc.Indian Acad. Sci.,1934,1, [A], 333; 1935,1, [A], 841; 2, [A], 143.lo Phil. Trans., 1934, [ A ] , 232, 463.l1 Proc. Roy. Soc., 1935, [A], 151, 585.l2 Proc. Physical SOC., 1935, 47, 571. l3 2. Physik, 1935, 96, 620BERNAL : CRYSTAL PRYSICS. 185' super-lattice.' If, however, the alloy is not annealed but quenchedfrom a sufficiently high temperature, we find that, while preciselythe same sites are occupied by atoms as in the super-lattice, thedistribution of the two metals between them is no longer regularbut purely random. Thus, in the example we have quoted, thestructure becomes essentially a face-centred cubic one, with a unitcell of the same size as before, but in which each site is occupied by($Cu + ~ A u ) .The transition between the ordered distribution in the super-lattice and the corresponding disordered arrangement has been thesubject of much recent work.14 All the authors agree in treatingit essentially as a problem of dynamic equilibrium in which the atomsseek to take up the ordered arrangement of lowest potential energy,while thermal agitation seeks to promote a state of disorder.Herewe shall follow in the main the discussion of W. L. Bragg andE. J. Williams, for although it cannot claim to be the earliest treat-ment of the order-disorder transformation, yet it contains manynovel features and has the additional advantage of being mathe-matically less formal than that of the other authors, and therefore,perhaps, more suitable for this Report.Consider a structure in a, condition intermediate between theextreme ordered and disordered states.Its state may be representedby a quantity X, the degree of order, whose value is unity for theordered arrangement of the super-lattice and zero for the state ofcomplete disorder. (The exact definition of X is irrelevant for ourdiscussion, and in fact, the quantity is differently defined by theseveral authors.) For a given value of 8, and a t a given temper-ature T, we may then define a quantity V as the increase in potentialenergy of the crystal when one atom is moved from an ordered to adisordered position. This quantity V is not a constant but afunction of X, for when X = 0 the distinction between ordered anddisordered positions vanishes and V must be zero; V will rise to amaximum value V,, when X = 1.As a first approximation, V isassumed to be proportional to X and to vary only slowly with T.The general form of the variation of V as a function of 8 at severaldifferent temperatures is shown by the curves of Pig. lb.If, now, we consider the crystal a t a temperature T, the conditionthat a degree of order X is one of dynamical equilibrium at thatl4 W. Gorsky, 2. Physik, 1928, 50, G4; U. Dehlinger, ibid., 1933,83, 832,and earlier papers; 2. physikal. Chew&., 1934, [B], 26, 343; A., 1934, 724;G. Borelius, Ann. Physilc, 1934, 20, 57, 650; A., 1934, 724; 1935, 24, 489;W. L. Bragg and E. J. Williams, Proo. Roy. rs(oc., 1934, [A], 145, 699; A.,1934, 954; 1935, [A], 151, 540; H.A. Bethe, ibid., 150, 552; A., 1193; W.Kume-Rothery and H. M. Powell, 2. Krist., 1935,91,23186 CBYSTAILOUItAPIIY.temperature leads to an expression for 8 as a function of V and 2'.Here we shall expect the form of the relation to be more exactlydetermined, for on the assumption of thermal equilibrium, thedistribution of atoms as between the ordered and the disorderedposition will be given by the Boltzinann relation as a function ofVIET. Without entering into details, we may say that Bragg andWilliams show that the general form of the relation will be thatshown by the curves of Fig. la. At low temperatures, or for largevalues of V , the degree of order approaches unity, while for smallvalues of V or under conditions of extreme thermal agitation, thedegree of order is very small.The equilibrium degree of order atany temperature T is given by the intersection of the two corre-sponding curvcs of Fig. 1. At high temperatures the only iiiter-section is a t 0, corresponding to complete disorder. At low temper-atures it is easy to see that the intersection at 0 corresponds to anunstable equilibrium, and that a second intersection a t a finite valueof S represents the stable equilibrium. This value of S tends tounity as T approaches zero. This second intersection will onlyoccur below a certain critical temperature T,, and from the natureof the curves it is clear that the point of intersection varies veryrapidly as T falls below this critical temperature. On cooling, thereis therefore a sudden onset of order below T,, followed by a moregradual increase towards unity.Formally, the theory of order-disorder is closely analogous t othat of ferromagnetism, the ordered form corresponding to theferromagnetic, and the disordered to the paramagnetic state ;T, corresponds to the Curie point.The existence of this critical temperature is the most importantfeature of the theory, for it is to be expected that at this temperaturemany of the physical properties of the alloy will display sharpchanges.In particular, anomalies in the specific heat will bBERNAL : CRYSTAL PHYSICS. 187expected, for as the temperature of the alloy is raised, extra thermalenergy must be supplied to break down the ordered structure of thecrystal.The specific heat will, therefore, rise gradually to thecritical temperature and then, all order being destroyed, fall abruptlyto its normal value. Bethe, who discusses the question of specificheats in rather more detail, shows that, although the order asdefined by Bragg and Williams disappears at the temperature T,,there is still a measure of ‘ local order ’ which persists above thistemperature and contributes to the energy of the structure. AboveT,, therefore, the specific heat of the alloy is still somewhat largerthan its normal value. In this iorm, the theory is in very satis-factory agreement with the specific-heat measurements of C. Sykes 15on the alloy CuZn.A somewhat different type of transformation between the orderedand disordered states takes place when the curves of Fig.la have apoint of inflexion, being curved to the x axis in the neighbourhoodof the origin. This will be the case, as Bragg and Williams show,for the alloy Aldu. Now, there will no longer be a continuous,albeit rapid, decrease of S as the temperature reaches T,, for therewill be a certain temperature a t which the curve of Fig. l b will betangential to that of Fig. l a , not at the origin but at some pointcorresponding to a finite value of 8. Above this temperature, thecurves will not intersect at all and the degree of order will fallabruptly to zero. In this case, the energy change associated with thetransformation must be regarded as a latent heat of transformationrather than as an anomalously high specific heat.Here again, thetheory is in satisfactory agreement with Sykes’s measurementson Cu,Au.In both cases the development of the ordered from the disorderedphase is a process which depends on the rate of cooling. At anygiven temperature below T, there is a definite rate a t which theorder increases. Bragg and Williams have shown that a time ofrelaxation T exists, after which the departure from equilibriumreaches 1 / e of iLs original value T, and which is given by e-logA(F1’T-l),where A = 10-12 sec. and TI is the temperature for which thetime of relaxation is I sec. If TIT, is 8, z is 30,000 years, so thatthe alloy will never in practice reach order at temperatures lessthan +Tl. This fixes another characteristic temperature, theimportance of which is that no ordered state for which T, < +TIcan ever be formed by cooling.This is the probable reason whysuperstructures other than very simple ones do not appear.The theory of order and disorder in crystal structures has beenstudied chiefly in metals, but :malogous phenomena are being15 Proc. Roy. Roc., 1935, [A], 148,422188 CRYSTALLOGRAPHY.observed with increasing frequency with other compounds, particu-larly among mixed oxides, sulphides, and halides. The interstitialand subtraction " Berthollide " compounds l 6 have, in general,atoms which occupy a larger number of lattice points, either regularly(ordered) or statistically (disordered). These compounds havebeen discussed by E. J. W. Verwey 17 and G. Htigg.l* Of particularinterest is the compound Ag,HgI, which exists in two forms-atetragonal form with definite positions of the metal atoms, and ahigher-temperature cubic form in which the metal atoms occupystatistically three out of the four octahedral positions.A moreextreme case is provided by the high-temperature form of silveriodideJ20 where the silver atoms occupy one of the three possibleoctahedral holes of the body-centred iodine lattice.Further examples of this phenomenon are (Li1Ti4+)0 2l withan NaCl lattice, Ce2,,W0, 22 isomorphous with CaWO,, the tungstenbronzes Na,W0,,23 in which the WO, lattice takes up Na atoms bylowering the tungsten valency, and the heteropoly-acids.24This phenomenon is closely related to the polysynthetic twinningwhich is being found very frequently in layer and chain lattices.Cadmium bromide,25 for instance, occurs in a cell containing one-third of a molecule due to existence of alternate layers of CdC1,and CdI, structures.Pd(NH,),C12,26 AgCN,27 and cristobalite 28show analogous two-dimensional lattices. Disordered and statisticalphenomena in crystals are, indeed, generally to be expected wheneve;.different structural arrangements exist having approximately thesame energy.Formally analogous to the order-disorder phenomenon is that ofthe rotation of molecules in crystals.29 The general theory hasnow been given by R. H. F0wler.3~ Two kinds of change occur, ingeneral. In the first, the inception of rotation coincides with ttchange of crystal structure and there is a definite latent heat.l6 See Ann.Reports, 1933, 30, 381.Is J. A. A. Ketelaar, ibid., 1934, 87, 436; A., 1934, 947; 2. physikal.2o L. W. Strock, 2. physikal. Chem., 1934, [B], 25,441; A., 1934, 834.21 E. Kordes, 2. Krist., 1935, 91, 193; 92, 139.23 J. Beintema, Proc. K. Akad. Wetensch. Amsterdam, 1935, 38, 1011.23 G. Hiigg, 2. physikal. Chem., 1935, [El, 29, 192; Nature, 1935, 135, 874.24 See ref. (97), p. 220.26 F. G. Manii, (Miss) D. Crowfoot, D. C. Gattiker, and (Mrs.) N. Wooster,2 7 C. D. West, 2. Krist., 1935, 90, 555; A., 1194; 1934, 88, 173.2 8 W. Nieuwenkamp, ibid., 1935, 90, 377.29 See Ann. Reports, 1931, 28, 290.30 Proc. Roy. SOC., 1935, [A], 151, 1; A,, 1197.17 J . Chem. Physics, 1935, 3, 592.2. Krist., 1935, 91, 114.Chem., 1934, [B], 26,327; 1935,30,53.26 See ref.(94), p. 209.J., 1935, 1642BERNAL : THE PROPERTIES OF REAL CRYSTALS. 189In the second, the inception of rotation is gradual, but it becomescomplete at a definite temperature : there is no latent heat but ananomalous rise in the specific heat. In general, these first andsecond types of change occur in different substances, but B. Ruhe-mann has shown that both occur in ammonium chloride, the firstat high the second at low pressures. L. Landau31 has given thetheory of this change-over, and has shown that a critical pressuremust exist at which the two types coincide. The theory cannot begiven here, but it expresses the fact that an increase of interactionbetween the movable parts beyond a certain degree causes all tomove when one does, and therefore a change from the second to thefirst type of transformation.J. D. B.THE PROPERTIES OF REAL CRYSTALS.The mechanical properties of real crystals, in so far as they departfrom those to be expected in a crystal having an ideal structure,were discussed in the last Report on Crystallography. During theperiod under review, however, the nature of the real crystal has beenthe subject of so many publications that no excuse is offered foronce again discussing this subject. Apart from individual papers,two especially important publications may be mentioned : vix.,the Report of the International Conference on Physics on theSolid State of Matter and an issue of the Zeitschrift fur Kristal-Eographie devoted entirely to the real crystal.Secondary Structure.-The conception of a crystal as having ablock-like structure was originally advanced to explain the fact thatthe observed X-ray reflexions from a crystal are very much moreintense and extend over a much wider angle than is to be expectedfrom an ideal structure.This conception has since been appliedin an attempt to explain many other ' structure-sensitive ' properties,notably breaking strength, which cannot be satisfactorily accountedfor in terms of the ideal lattice. The exact nature of this secondarystructure, and even its very existence, is still, however, the subjectof violent controversy. Thus, while many results are interpretedin terms of such a structure, and others 3 are alleged to give directproof of its existence, other authors 4 have marshalled many factswhich they claim render such a structure impossible, and at theThe Physical Society, London, 1935 ; hereafter referred to as Phycl.SOC.31 Physikal. 2. Sovietunion, 1935, 0, 113.Rep.1934,89, 193-415.3 F. Bitter, Physical Rev., 1932, 40, 125; A., 1933, 1234.H. E. Buckley, 2. Krist., 1934,89,221,410; A., 1935, 150; M. J. Buerger,ibid., p. 242190 CRYSTaLLOQEAPHY.same time criticise the evidence on which the secondary structureis based. Among the principal objections to a mosaic structure ofthe type postulated by Zwicky are: (1) The fact that coherentcrystals can be grown 8,s thin plates or hairs with linear dimensionsless than those of the mosaic blocks.(2) The internal perfectionof crystals which makes their use in optical systems possible.(3) Intersecting glide planes. Gliding is supposed to take place onso-called x-planes : gliding on two intersecting n-planes couldonly occur if the glide distance was an exact multiple of the n-planespacing. (4) Crystal strength. The very low strength of crystals,compared with the value calculated from the ideal structure, doesnot require any secondary structure and can be explained as due toa tearing of the crystal starting from surface cracks.5 A. Joff66has shown that under appropriate conditions strength approximatingto the theoretical can be achieved, while with glass, where there isno question of mosaic structure, the abnormally low strengthobserved can be attributed to tearing.Mica stretched in such away that the edges remain stressless increases in strength ten times.( 5 ) The energetics of the problem.’A number of interesting observations have been explained byA. Goetz 8 in terms of a ‘ group ’ structure, but here again there aremany object ions. 9Another type of secondary structure, which seems to be lessopen to criticism, is the ‘lineage structure’ of M. J. Buerger.10Mere all crystals are regarded as essentially filled in dendriticframeworks. The lack of perfect parallelism between lineagesaccounts for the observed decrease in X-ray extinction, but thestructure is essentially not a mosaic one. It is only accurate toapply the term mosaic to one cross section of the crystal, for inthree dimensions the mosaic ‘ blocks ’ join one and the same parentstock at the original crystal nucleus.The ‘ blocks ’ are lineagesjust as are the branches of a dendrite. Buerger supports his viewsby a number of beautiful photographs, and is able to account in ageneral way for most of the structure-sensitive properties normallyexplained in terms of a secondary structure. In this connectionwe may refer the reader t o the work of A. Papapetrou l1 on the growthof dendritic crystals.On the experimental side, the extreme difficulty of obtainingreproducible results, and the amazing discrepancies between theE. Orowan, Phys. SOC. Rep., p. 81; 2. h7rist., 1934, 89, 327; A., 1935, 151.cI Phys. SOC. Rep., p. 77.7 M. J. Buerger, 2.Krist., 1934,89, 242; E. Orowan, Phys. SOC. Rep., p. S1.* 2. Krist., 1034, 89, 310; A., 1935, 151; Phys. SOC. Rep., p. 62.H. E. Buckley, 2. Krist., 1934, 89, 221; A., 1935, 150.l1 Ibid., 1935, 92, 89. 50 ITbid., p. 195BERNAL: THE PROPERTIES OF REAL CRYSTALS. 191observations of different schools, make it difficult to establish anyunquestionable conclusions, To instance only one example, allauthors are agreed that wetting a rock salt crystal has a profoundeffect on its plastic properties and breaking strength. K. Wenden-burg l2 argues that the effect is st volume one due to penetration ofthe water into the crystal, since the effect persists if the surface issubsequently dried. Absorption spectra are also said to revealthe presence of water in the crystal.A. J0ff6,13 however, claims thatthe effect cannot be a volume one since the strength of a wettedcrystal, one region on the surface of which is protected by vaselin,is that of a dry crystal. If water entered the volume of the crystalit would penetrate to all parts in spite of the vaselin.That a secondary structure is not an essential characteristic ofcrystal is indicated by the fact that crystals of rock salt can beprepared l* which give the X-ray reflexion deduced from the ideallattice. A summary of existing theories of real crystals is givenby A. Smekal.l5Plasticity.-Closely allied to the question of secondary structureis that of the plastic properties of single crystals. In the " Distor-tion of Metal Crystals " 16 and elsewhere,l' accounts are availableof the many observations on plastiic deformation. The essentialfeatures which any theory of plasticity must explain are : (1) Plasticdistortion sets in when the shear stress reaches a certain criticalbut very small value.(2) The distortion may take place eitherby gliding along definite crystallographic planes in, definite directions,or by twinning. (3) The occurrence of plastic deformation isalways accompanied by a ' hardening ' or increase in 'the stressrequired to produce further deformation. In this connexion, it isimportant to realise, as A. W. Stepanow has pointed out, thatbreaking strength and plasticity are in no way related, and that noincrease in breaking strength takes place on plastic deformation.The anomalously low breaking strength, as we have seen, is to findits explanation in the secondary structure : it can only be measuredunder conditions in which plastic flow is prevented.12 2.Krist., 1934,88, 727; A., 1934, 721.13 Phys. SOC. Rep., p. 72; see also E. W. Zehnowitzer, Nature, 1935, 135,1076; A., 956.14 M. Renniger, Naturwiss., 1934, 22, 334; A., 1934, 720; 2. Krist., 1934,89, 344; A., 1935, 151 ; P. P. Ewald and M. Renniger, Phys. SOC. Rep., p. 57.15 2. Krist., 1934, 89, 386; A., 1935, 161.16 (Miss) C. F. Elam (Oxford, Clarendoir Press, 1935).17 W. G. Burgers, Phys. SOC. Rep., p. 139; E. Schmid, ibid., p. 161; W. G.Burgers and J. M. Burgers, First Report on Viscosity and Plasticity, Verh.K. Akad. Amsterdam, 1935,15,173.18 2.Physik, 1934, 94, 42192 CRYSTALLOGRAPHY.The same author l9 has suggested that plasticity may be accountedfor in terms of the intense local heating developed in the neighbour-hood of the glide planes, which produces a temporary dissociationof the lattice. That such a mechanism is not impossible is indicatedby the experiments of F. P. Bowden and K. E. W. Ridler,20 whofound that the surface temperature of sliding metals may reachvery high values although the bulk of the metal remains at roomtemperatures. High temperatures produced by plastic deformationmay play an important part in detonation.21 The great plasticityof silver chloride compared with that of rock salt, which has the samestructure and very nearly the same lattice dimensions and latticeenergy, suggests that the difference may be due to the differenceof polarisation properties of sodium and silver, which also accountsfor the absence of cleavage in silver chloride.22A more precise, mathematical theory of the plasticity of crystalshas been developed by G.I. Taylor,23 who pictures slip as takingplace by the propagation of a ' dislocation ' along the slip plane.Such a ' dislocation ' may be pictured by considering a point P inthe slip plane, such that some distance beyond P the lattice iscontinuous across this plane, while at some distance on the otherside of P the lattice is again continuous but with the portion on oneside of the slip plane displaced relative to that on the other throughthe length of the unit cell.In the immediate neighbourhood of P ,.the lattice is distorted, but where P has passed along the slip planethe ideal lattice is restored except that one half is displaced relativeto the other. To bring about such a displacement by causing allthe atoms in one plane to jump simultaneously through the lengthof one unit cell would require a force of the order of magnitude of theelastic modulus, but if the displacement occurs by the atoms in theneighbourhood of the dislocation jumping one by one, therebypropagating the dislocation, the force required is much smaller,since the field of force in the immediate neighbourhood of the dis-location is profoundly altered. Calculation shows, in fact, that underthe influence of the smallest stress, thermal agitation alone shouldsuffice to propagate the dislocation, so that an ideal lattice shouldbe infinitely weak.Taylor overcomes this objection by supposingthat, after travelling a distance L, the dislocation encounters oneof the ' faults ' of the secondary structure and then stops. In thisIs 2. Physik, 1933, 81, 560.20 Proc. Cam&. Phil. Xoc., 1935, 31, 431.21 A. Michel-L6vy and H. Muraour, Compt. rend., 1934,198,1499; A., 1934,22 A. W . Stepanow, Physikal. 2. Sovietunion, 1934, 6, 312 ; 1935, 8, 25.23 Proc. Roy. SOC., 1934, [A], 145, 362, 357; A., 1934, 950; 2. Krist., 1934,605.89, 376; A., 1935, 151EVANS : CRYSTALLOURAPHY. 193way a parabolic relation is derived between the stress and the amountof plastic distortion, which is in good agreement with observationson rock salt and metal crystals.The experiments enable a value ofL of about 10-4 cm. t o be deduced, and this is of the correct order ofmagnitude for most of the theories of secondary structure.Another picture of the mechanism of plastic deformation, due toE. Orowan,24 regards it as essentially a dynamic phenomenon.Consider a crystal under the influence of a shearing stress T,, itselfinsufficient to cause gliding. Under the influence of local thermalfluctuations, the stress will occasionally reach a value exceedingsome critical value TR and local slip will take place. This is mostlikely to happen at places where the stress is already concentratedowing to material inhomogeneities, so that we must replace the meanstress 7, by cpa, where q is a factor expressing the local concentrationof stress.The increase of stress from qz, to TR corresponds to anincrease of elastic energy proportional to (TR - q ~ # , and it istherefore assumed that the probability of such an occurrence isgiven by the Boltzman equation W = const. x e - h - P Q l k T . Thevelocity of the deformation process is evidently proportional to thisprobability. In this form, the theory gives a finite rate of deform-ation for all values of the applied stress. The exponential factor,however, results in such a rapid increase in velocity with appliedstress that there will be some critical stress below which the velocityis too small to be observed, as is found to be the case experimentally.Orowan’s theory gives a satisfactory account of the parabolicrelationship between stress and amount of deformation, and also ofthe observed temperature variation of critical stress.A suggestedcombination of the theories of Taylor and Orowan has been advancedby Burgers and Burgers.25 J. D. B.CRYSTALLOGRAPHY.The Technique of Structure Analysis.-The field of X-ray structureanalysis has enjoyed two important additions to its bibliographyduring the period under review. ‘‘ International Tables for CrystalStructure Determination ” is the outcome of the work of an inter-national committee of crystallographers set up 1929,2 and containsa wealth of information for those engaged on structure analysis.The first volume comprises diagrams of the equivalent generalposition in the 230 space groups, together with the structure factorsand a list of the characteristic reflexions both for the general and24 2.Physik, 1934, 89, 605, 614, 634; 1935,97,673.25 Op. cit., ref. (17).2 See Ann. Reports, 1931, 28, 263.1 Bell, 1935 (two vols.).REP .-voL. XXXII. 194 CRY STALLOGRAPHY.for special positions in each space group. The second volumecontains tables of many trigonometrical functions and physicalquantities frequently required in structural analysis, as well as anaccount of graphical methods of interpreting X-ray photographs." X-Rays in Theory and Experiment," 3 a second and greatlyenlarged edition of " X-Rays and Electrons," contains some 150pages devoted to a very full account of the theory of the diffractionof X-rays by a crystal grating, much of which was previouslyunavailable in the English language outside original papers.The experimental methods of structure analysis have suffered nofundamental changes in the last two years.Two papers,4 dealingwith the Weissenberg camera and with the interpretation of thephotographs obtained, reflect the increasing use which is being madeof this instrument. Photographic methods of intensity measure-ment have now become a common practice. I n a moving-filmcamera described by J. M. Robertson,s the crystal under investi-gation and a standard crystal are alternately exposed to the X-raybeam so that a number of reflexions of known intensity are presenton the film: by comparison with these reflexions, unknown intensitiescan be determined with an accuracy amply sufficient for structureanalysis in a fraction of the time required for ionisation-spectrometermeasurements. The method, moreover, is available for manysubstances which will not form crystals sufficiently large for use onthe ionisation spectrometer.Conditions necessary for makingaccurate intensity measurements on powder photographs have beendiscussed by G. W. Brindley and F. W. Spiers,6 by J. C. M. Brentano,'and by B. W. Robinson.'" Precise measurements of lattice constantsand the geometrical and other errors which arise in such measure-ments are reviewed by several authors.8 Various methods have beensuggested 9 for reducing the exposure times required for powderphotographs.New forms of camera suitable for use a t low temper-atures or where the crystal must be kept in a vacuum have beendescribed by E. Pohland lo and by B. Ruhemann.113 A. H. Compton and S. K. Allison (Macmillan, London, 1935).4 M. J, Buerger, 2. Krist., 1934,8S, 356; (Miss) D. M. Crowfoot, ibid., 1935,Phd. Mag., 1934,18, 729.6 Proc. Physical SOC., 1934, 46,, 841.7 0 Proc. Roy. Xoc., 1934, [ A ] , 147, 467.8 M. U. Cohen, Rev. Sci. Instr., 1935,6,68 ; J. Koppel, J. Phys.Radium, 1934,5,145 ; A., 1934, 587 ; E. R. Jette and F. Foote, J . Chem. Physics, 1935,3,605.9 W. E. Schmid, 2. physikal. Chem., 1933, [B], 23,347; A., 1934,162; J. P.Blewett, J . Sci. Imty., 1934, 11, 148; A., 1934, 624; A. Rogozinski, Compt.rend., 1934, 198, 963; A., 1934, 503.90, 215.Ibid., 1935, 47, 932; A., 1306.10 2.physikal. Chem., 1934, [B], 26, 238; A., 1934, 985.11 Physilcal. 2. Sovietunion, 1935, 7, 572EVANS : CRYSTALLOGRAPHY, 195The great power of X-ray methods, and especially of the powdermethod, in attacking many problems of a more general characterthan those involved in pure structure analysis, is a t last beingrecognised. Such varied problems as a qualitative and evenquantitative chemical analysis of material of which only minutequantities are available, the determination of grain size in metalsand other crystalline substances, and the detection of strain incastings, have all been successfully attacked by X-ray methods.An investigation l 2 into the constitution of bleaching powder waslargely carried out by these methods, while W.P. Jesse l3 hasdescribed quantitative analyses of metal systems accurate to 1 yo. Aspecial number of the KoZZoid Zeitschrift (1935,69, Heft 3) is devotedto X-ray and electron methods in colloid science, while a popularaccount of such applications of X-ray analysis, especially in theindustrial field, has been published.l4 Yet it is true to say that thereare many investigations to which these methods are particularlysuited which are still being attacked by older and less satisfactorymeans.One important contribution has appeared during the periodunder review which promises to be of considerable value in theelucidation of complex structures. The representation of theelectron density throughout a structure, as projected on anyplane in the structure, by means of a Fourier synthesis affords anelegant means of presenting the results of a structure analysis.It is not, however, of great value in determining an unknown stmc-ture, for although intensity measurements give us the magnitudesof all the terms of the Fourier synthesis, they can tell us nothing ofthe signs.These signs can only be determined when the positionsof most of the atoms in the structure have been found by otherexperiments. A. L. Pattersonl5 has shown that, if we form theFourier synthesis, using not the amplitudes but the intensities ofthe X-ray reflexions as the coefficients of the corresponding terms inthe synthesis, the resultant plot is such that the vectors joining theorigin to each of the several peaks represent in length and direction,but not, of course, in position, interatomic distances in the structure.In Fig.2a an example of such a plot is given for hexachlorobenzene.This substance is monoclinic, and the plane of the benzene ring isnearly parallel to the (010) face. Fig. 2b shows a projection of thel4 C. W. Bunn and others, Proc. Roy. SOC., 1935, [A], 151, 141 (see this vol.,p. 158).13 Rev. Sci. Instr., 1935, 6, 47; A., 1934, 446.1 4 “ Industrial Application of X-Ray Crystal Analysis,” H.M. StationeryPhysical Rev., 1934, 46, 372; A., 1934, 1160; 2. Krist., 1935, 90, 517,Office, 1934.543; A., 1193196 CRYSTALLOGRAPHY.molecule on this face, and all the prominent peaks in Fig. 2a may bereadily associated with the corresponding interatomic distancesin the molecule.The distances in Fig. 2b give rise to the peaks inFIG. 2a.Hexachlorobenxene. Contour map of the F2(h01) series.Fig. 2a bearing the same letters. I n more complex structures, thenumber of interatom distances will be so large that only the mostprominent between the heaviest atoms will be expected to stand outFIG. 2b.Interatomic distance diagram for the C,C1, molecule.of carbon atoms, the outer of chlorines.repeated six times iia approximate hexagonal symmetry.centrosymmetrical.bearing the sa.me letters.T h e inner ring consistsT h e interatomic distances indicated areT h e molecule is actuallyThe distances in this diagram give rise to the peaks in P i g . 2aain a Patterson synthesis, and to this extent the method has itslimitations and perhaps gives little more information than would bededuced from general considerations by an experienced worker iBERNAL AND WELLS : CRYSTAL CHEMISTRY.197structural analysis. At the same time, the Patterson synthesisdoes afford the only means of giving an unprejudiced presentationof all the information which may be directly derived from theexperimental material. The method has already been applied to adetermination of the structure of nickel sulphate heptahydrate 16where it threw considerable light on the position of the nickel andthe sulphur atoms.The tedious calculations involved in the formation of a Fouriersynthesis may be considerably lightened by the methods of C.A.Beevers and H. Lipson l7 and J. M. Robertson.18 R. C. E.CRYSTAL CHEMISTRY.There have been no notable advances in general crystal chemistryin the past two years. The generd picture elaborated by Bragg,Goldschmidt, and Pauling still continues to hold the field. L.Pauling and M. L. Huggins have, however, extended their workon atomic dimensions to include covalent binding. In an importantpaper they discuss the theory of the covalent link on the basis ofthe directed bond picture. This enables them to predict themagnetic moments to be associated with the four types of bondsdiscussed, viz., the tetrahedral bonds sp3, the square bonds dsp2,the octahedral bonds d2sp3, and the 8-co-ordinate bonds d4sp3. Inthis way they are able to distinguish between ionic and co-valent bonding in complexes.For instance, they show that theFeF, complex is essentially one of ionic bonds, whereas Ii’e(CN),has covalent bonds. In a semiempirical way they construct tableswhich give an effective radius for tht! tetrahedral, square, and octa-hedral and trigonal prism radii. These tables are given below.Be.1.072 0cu.1.35Age1.53Xtandard Tetrahedral Radii.B. C. N. 0. F.0.89 0.77 0.70 0-66 0.64A1 . Si. P. S. c1.1-26 1.17 1.10 1-04 0.99Zn. Ga. Ge. As. se. Br .1.31 1.26 1-22 1.18 1.14 1.11Cd. In. Sn. Sb. Te. I.1.48 1.44 1.40 1.36 1-32 1.28Au. w* T1. Pb. Bi.1.50 1.48 1.47 1.46 1-46l6 C. A. Beevers and C. M. Schwartz, 2. Krist., 1935, 91, 157.l7 Phil. Mag., 1934,17, 855. l8 Ibid., 1936, 21, 176.2.Krist., 1934, 87, 206; A., 1934, 350198 CRYSTALLOBRAFRY.8tandard Octahedral Radii (from Pyrite-type Crystals).Valency. Fe. Co. Ni. %I 7:) 53 29I1 ............ 1-23 1.32 1.39 1.33 1.43 1.50 1.84 *III ............ 1.22 1-31 1.32 1.42 1.491.31 1.41 IV ............ 1.21* Obtained by extrapolation.Square Radii.CoI. NiII. CUIII. RhI . PdK AgnI.IrI. PtII. AuIII.1.23 1.22 1.21 1-33 1-32 1.31Trigonal prism radii : Mo, 1.37 ; W, 1.44.These radii would be better called half-bond lengths, as thecovalencies are definitely directed, and the radii of the atoms,other than covalent bonds, may be as much as twice as large.H. G. Grimm 2 has made a general survey of chemical compoundsof the type A,BB,. He has discussed the conditions which determinetheir general character-metallic, adamantine, ionic, and molecular-and has produced a table showing the known type of compoundsformed between every pair of elements in the periodic table.R.C. Evans, in translating 0. Hassel’s “ Crystal Chemistry”(London, Heinemann), has made available in English a simple andattractively written account of the subject, but one which unavoid-ably does not include much recent work. R. W. G. Wyckoff hasproduced an extremely valuable supplement to the second edition of“ The Structure of Crystals,” which gives references and beautifullydrawn diagrams to all of the important crystal structures determinedin the years 1930-1934. Pending the second edition of the“ Strukturbericht,” this is a most valuable compilation for chemistsand crystallographers, particularly because every structure iscritically examined and those described may be considered to bewell established.MeiaZZic 8tructures.-Our knowledge of the electronic theory ofmetals, discussed earlier in this Report, has been of great assistancein understanding the crystal structure of metals and alloys, and has,in general, justified the empirical classification put forward inprevious reports. Three main factors are found to influence thesestructures : the sizes of the atoms, the number of electrons per atomin the phase as a whole, and the heterogeneity of the atoms composingthe alloy.Most of the alloy structures investigated earlier had atoms ofapproximately the same size, and consequently this factor did notenter into consideration.The three types of alloy distinguishedAngew. Chem., 1934, 47, 53; A., 1934, 234BERNAL AND WELLS : CRYSTAL CHEMISTRY. 199were those in which the atoms wcre of the same electronic type,which gave rise to unbroken solid solutions, such as the systemgold-silver; those in which the atoms had a different number ofelectrons, and consequently where the average number of electronsper atom varied with the concentration-these are the substanceswhose structures obey the Hume-Rothery rules now explained byJones-and finally, alloys where the difference of the number ofelectrons is very great, sometimes tending to pass over into semi-metals. The sequence, as given hy U. Dehlinger3 in a generalreview of metallic mixed crystals and compounds, is as follows:Mixed crystals, super-structures, inter-metallic compounds, corre-sponding to increasing affinity, a diminished region of homogeneityand an increasing difference in physical properties and crystalstructure compared to the component metals.No hard and fastlines can be drawn between these different types of combination,and this gives metal chemistry a particularly indefinite character.The r61e of differences in atomic size is beginning to be apparent.Two compounds have been known for some time, vix., Cu,Mg andZn,Mg, which may be described as close-packed structures of copperor zinc respectively with cubic and hexagonal close-packed latticesin which a large magnesium atom is inserted in the place of twocopper or zinc atoms.These types are now found to have a farwider significance, and to occur, in fact, in nearly all cases where theradii of the atoms concerned are in a, ratio of between 1 : 1-15 and1 : 1.3, or a volume ratio of approximately 1 : 2. Thus, F. Lavesand K. Lohberg * have pointed out that ME,, ZrW,, PbAu,, CuBe,,and MgNiZn belong to the MgCu, type, while MgNi,, MgCuAl,FeBe, belong to the MgZn, type. The occurrence in these lists ofmetals of a totally different chemical nature shows that thestructures cannot be due to any electronic factors, but are simplythe expression of the nearest approach to close-packing which canbe made by atoms of widely different atomic volume. They maybe regarded as substitution compounds or solid solutions in whichone atom of one type replaces two of another and, as Laves hasshown, such compounds are not confined to binary alloys.Thus thequaternary compound Mg,Zn2Cu2Ni, belongs to the Cu,Mg type,There are probably a limited number of other such compounds withdifferent volume and atom ratios : thus Zn,Mg and FeBe, possessmodifications of the Zn,Mg and the Cu,Mg structure respectively.The simplest cases of all are where adloys are of the form AB, thestructure of which is the well-known czesium chloride type, while3 Angew. Chem., 1934, 47, 621 ; 2. Metallk., 1934, 26, 227 ; %. Elektrochem.,1935, 41, 344; cf. W. E. Schmidt, 2. Metalllc., 1935, 27, 49.4 Nach. Ges. Wiss. Cottingen, 1934,1, 69200 ORYSTALLOGRAPHY.A1,Cu is an example of a type in which the small copper atoms arepacked in the interstices of a deformed cubical close-packing ofaluminium atoms.Further research will undoubtedly bring tolight many more such compounds. They are likely to show amuch more definite composition than those in which the atom sizesare more equal. But this is a purely geometrical fact, and does notdepend on any greater chemical affinity between the elementscomposing them.The existence of an intermetallic compound may be due to threereasons by no means inutually exclusive. In the first place, it maybe due simply to the existence in some simple ratio of atoms ofdifferent kinds. Such compounds will range from the orderedclose-packing discussed above to the definite structures due toatoms of unequal sizes.Secondly, it may be due simply to theaverage number of free electrons available per atom, but this islikely to have a determining effect on the structure only when theatomic sizes are approximately equal. Thirdly, it may depend onthe existence of loosely held electrons in one atom and electronaffinity in the other. This will lead to further definite compoundswhich are strictly not all of a metallic character, such as Mg,Pb.Modern methods of the exact measurement of lattice dimensionshave made it possible to get a closer view of the nature of inter-metallic solid solution. E. R. Jette,5 in a study of available inform-ation, shows that solid solutions can be divided into three types, inall of which the lattice constants are less than, equal to, or greaterthan that expected from Vegard's law : a = aAFA + a,$',, whereP denotes atomic fractions.A smaller lattice constant indicatesthe special attraction between unlike atoms, a larger one a specialattraction between like atoms. The former is shown by thesystems Ag-Pb, Ag-Pd, Cu-Ni, and Cr-Fe, the latter by Cu-Au,Cu-Pd, Cu-Ag., . .Ag-Cu, Fe-Cr, and with Au-Pt, Au-Pd, Mo-W,Pt-Ir, Pt-Rh, Sb-Bi, there is no sensible deviation from Vegard'srule. The negative and positive variations can be correlatedvery roughly with the slope of the liquidus curve tending to beconvex for negative, and concave for positive deviations, as mightbe expected.The use of high-precision determination of lattice constants willsoon become the most reliable gauge of purity of a metallic element.E.R. Jette and F. Foote have determined the lattice constants ofspecially Pure M , Ni, Ag, Au, si, Be, Mo, W, Mg, Zn, Cd, Sb, Bi, andSn, with a general accuracy of 1-2 parts in 40,000. Similar, butless accurate, determinations of other elements have been carriedti Arner. I n s t . Min. Met. Eng., 560 E.J. Chern. Physics, 1935, 3, 605201 BERNAL AND WELLS : CRYSTAL CHEMISTRY.out by E. Owen, L. Pickup, and I. 0. Rioberts 7 and M. C.Neuburger .8New super-structures Au,Mn and AuMn, face-centred and body-centred tetragonal respectively, have been found to be precipitatedat low temperatures from the extended solid solution of manganese-g0ld.9 The only compounds of the transition metals which showdefinitely novel structures are the related substances Fe,W andPe,W6, and the corresponding molybdenum compounds determinedby H.Arnfelt and A. Westgren.lo In these structures there seemsa definite tendency for tungsten or molybdenum atoms to associatein groups of two or four.The interstitial compounds have been further investigatedwithout, however, any startling discovery. Further work has beendone on the solubility of hydrogen in the transition metals,ll andthe essentially protonic nature of the solution confirmed. Thestructure of steel is now, thanks to X-ray work, fairly firmlyestablished. G. H&gg l 2 has finally shown, by careful measure-ment of lattice parameters, that the only martensite formed byquenching of austenite (face-centred y-iron containing carbon) hasa tetragonal structure which gradually approximates to cubica-iron with decrease of carbon content.The rate of decompositionof the martensite is shown to depend primarily on the temperature,but it is appreciable even at 100". An excellent popular accountof our present knowledge of the structure of steels is given byI(. van Horn.13 A higher carbide of iron, Fe,C, has been described.14The highest carbide of nickel so far found is Ni3C,15 which consistsof a hexagonal close-packed nickel structure with statisticallydistributed carbon atoms.A study of the system Fe-Cr-N 1s shows only, besides the knowniron nitrides, two chromium nitrides, Cr,N, hexagonal, and CrN,cubic face-centred; but in the Fe-Al-C system l 7 a new phaseFe,AlC, is found, face-centred cubic, in contrast with the body-centred Fe,Al.A certain solubility of carbon in platinum has heen7 2. Krist., 1935, 91, 70.9 H. Bumm and U. Dehlinger, Metallwirt., 1934, 13, 23.10 Jernk. Ann., 1935, 185.11 H. Mundt, Ann. Physik, 1934, [v], 19, 721 ; A., 1934, 590; D. P. Smithand G. J. Derge, Trans. Electrochem. SOC., 1934,66, 25 ; A.9 1934, 1168 ; M. H.Hey, J., 1935, 1254; A., 1322; J. Franclr, Nach. Ges. Wiss. GGttingen, Math.-phys. KI., 1933, 293; A., 1934, 1168.12 J . Iron Steel Inst., 1934, 11, 439; cf. J. Bpkhal and F. Cabicar, GoZZ.Czech. Chem. Comm., 1934, 6, 251; A., 1!334, 953.13 Metal Progress, Aug. 1035.16 J. Schmidt, 2. anorg. Chem., 1933-34, 216, 85.16 S.Eriksson, Jernk. Ann., 1934, 630.17 F. R. Morral, J . Iron Steel Inst., Sept. 1934; A., 1934, 1166.* Ibid., 92, 313; 1936, 93, 1.1 4 G. Hiigg, 2. Krist., 1934, 89, 92.6 202 CRYSTALLOGRAPHY.reported.18 The complex structures of the carbides of chromiumCr,C, and manganese Mn7C, with 80 atoms in the cell have beenworked out by A. Westgren.lg They consist of carbon placedinterstitially into a distorted metal framework. The silicidesof the transition metals have also been studied, particularly byB. Bor6n.20 Cr, Mn, Co, and Ni all form compounds of the typeMSi, showing the FeSi structure. The isotropic Mn,Si, alsostudied by F. Laves,21 is interesting as a simple body-centredstructure in which manganese and silicon atoms occupy all positionsindiscriminately. In Co2Si there is an arrangement of siliconchains similar to those existing in Cr,C,,22 the Si-Si distance in thechains being 2.15 A.23Electron Compounds.-No full account of X-ray studies of thisfield is given, as it is covered by the Report on non-ferrous alloys(p.165). Only references will be made to newly established crystalstructures.Now that the theoretical basis for Hume-Rothery’s rules hasbeen established (see above), special interest attaches to the studyof solubility limits of the system copper-silver, and the B-groupelements including gallium, germanium, and indium. 24 In all caseswhere large differences of atomic size do not occur, the equilibriumdiagrams depend on electronic and not on atomic proportions asthe theory demands. I n the nickel-zinc system 25 the tetragonalphases p and y correspond approximately to the fi-brass and E tothe y-brass type.Ferromagnetic Heusler alloys, Mn-Al-Cu, arefound to belong essentially to the P-type, with a regular super-structure.26 A. J. Bradley and J. W. Rodgers 27 bave used anextremely ingenious method to differentiate the positions of thecopper and manganese atoms. These are normally indistinguishableby X-rays, but by using iron, copper, and zinc K radiation, anomaliesin the scattering power of the elements in relation to the positionof their absorption edges enable the distinction to be made.18 L. J. Collier, T. H. Harrison, and W. G. A. Taylor, T r a n s . Faraday SOC.,1934, 30, 581 ; A., 1934, 987.Jernk.Ann., 1935, 231.2o ArEiv Kemi, Min. Geol., 1934, 11, A , No. 10; A., 482.21 2. Krist., 1935, 89, 189.23 B. Boren, S. StAhl, and A. Westgren, 2. physikal. Chem., 1935, [B], 29,231; A., 1194.24 W. Hume-Rothery, G. W. Mabbott, and K. M. C. Evans, Phil. Trans.,1934, [ A ] , 233, 1 ; A., 1934, 725.25 K. Tamaru and A. Osawa, Bull. I n s t . Phys. Chem. Res. Japan, 1934, 13,13; A., 1934, 482; Sci. Rep- T&oku Imp. Umiu., 1934, 23,794; V. Caglioti,Atti Congr. naz. Chim., 1933, 4, 431; A., 1934, 1166.22 See Ann. Reports, 1933, 30, 390.2 6 0. Heusler, 2. Metallk., 1933, 25, 274; A., 1934, 357.2 7 Proc. Roy. Soc., 1934, [ A ] , 144, 340; A . , 1934, 590BERN& AND WELLS : CRYSTAL CHEMISTRY. 203New p- and 7-phases have been found in the copper-gallium 28 andcopper-indium 29 systems, but anadogous compounds do not occurin the silver-indium system.30 The y-structure which occursanomalously for CuHg has been confirmed.31New compounds and new structures have been found in theFe-A1 system.32 The compounds FeAI,, Fe2A15, and FeA1, are allhighly complex; FeM3 has a moiioclinic cell of dimensions 47.4,15.4, 8.1 ,&., containing 400 atoms.33 The platinum-thalliumsystem contains one compound PtTl with a new and unusual struc-ture.34 The purple compound AuAl, proved t o have a simplefluorite type of structure,35 which may have some relation to itsunusual physical properties.The silicides of the B-group metalshave been much studied ;36 one, C U ~ ~ S ~ ~ , has a cubic cell containing76 atoms.Compounds where large differences of atomic size occurhave also been studied;37 in particular, L. Misch has studied thecompounds of beryllium with copper, nickel, and iron :38 CuBe andNiBe have the czsium chloride structures, CuBe, and NiBe, are ofthe MgCu, type, and FeBe, is of the MgZn, type ; while Ni,Be2, andPt5Be2, have a deformed y-brass structure.Our knowledge of the alloys ofthese metals has been considerably extended. U. Dehlinger 39has made a useful survey of the known alloy structures and solidsolutions of the elements Be, Mg, Zn, Cd, Hg, Al, and Sn. Itappears quite definitely that the factors conducing to extendedsolid solution are similarities in electronic constitution rather thanmere equivalence of atomic size.F. M. Jaeger and J. E. Zanstra 40Alloys of A- and B-group metak.2 8 F. Weibke, 2. anorg. Chem., 1934, 220, 293.29 F. Weibke and H. Eggers, ibid., p. 273.30 Idem, ibid., 1935, 222, 145; L. K. Prove1 and E. Ott, J . Amer. Chem. SOC.,31 F. Schoszberger, 2. physikal. Chem., 1935, [B], 29, 65.32 A. Osawa, Sci. Rep. Tbhoku Imp. Univ., 1933, 22, 803; A., 1934, 137;Kinz. no Kenk., 1933,10,432; A., 1935, 158.33 E. Bachmetew, 2. Krist., 1934, 89, 575.34 E. Zintl and A. Harder, 2. Elektrochem., 1935, 41, 767.36 C. D. West and A. W. Petersen, 2. Krist., 1935,88, 93.36 E. R. Jette and E. B. Gebert, J . Chem. Physics, 1933, 1, 753 ; A., 1934,137; F. R. Morral and A. Westgren, Arkiv Kemi, Min. Oeol., 1934, 11, [B],No. 37 ; A , , 1934, 1165; K.Sautner, Porschungsarb. Metallk. Riintgenmet.,No. 9 ; A., 1934,482 ; S. Fagerberg and A. Westgren, Metallwirt., 1935,14,265.37 V. G. Sederman, Phil. Mug., 1934, [vii], 18, 343; A., 1934, 953; H.Perlite, Keemia Teated, 1934, 2, 11; A.., 1934, 1064; C. Dbgard, 2. Krist.,1935, 90, 399 ; A., 1198 ; T. Jurriaanse, ibid., p. 323.1935, 57, 228.38 2. physikal. Chem., 1935, [B], 29, 42.39 2. Elektrochem., 1935, 41, 20.PTOC. K. Akad. Wetensch. Ameterda,m, 1933, 36, 636 ; F. M. Jaeger and E.Rosenbohm, ibid., 1934, 37, 67 ; Rec. trav. chirn., 1934, 53, 451 ; A., 1934,589204 CRYST~OGRAPBY.have made a, detailed study of the allotropy of beryllium; themetastable form at 600" is orientated parallel to the original beryl-lium crystals and must be in some sense a super-lattice of dimensionsa = 7-1, c = 10.8 A.Such a lattice would contain about 60 atoms,and the exact determination of this structure would have greattheoretical interest.The alloys of lithium have been extensively studied, chiefly byG. Grube, E. Zintl, and their collaborators.there is no true compound formation, but the solid solution ofcomposition LiMg, cannot take up any more magnesium, andfunctions towards it as a true compound. Apart from the com-pound LiZn,42 with the NaTl structure, another compound Li,Zn,is formed of a pseudo-hexagonal close-packed structure. Thelithium-cadmium alloys have given rise to considerable controversy.It appears, however, that both sides may be right : that the quenchedLiCd has a true cEsium chloride structure, as A.Baroni 43 maintains,and that the tempered alloy has the more ordered NaTI structure.44Two more compounds, LiHg, and Li,Hg, have been established,and hexagonal and cubic structures have been determined.45LiAl 46 has an NaTl structure. The structure Mg3Al, is of excep-tional interest, for here among the A-group metals we have the samecomplicated structure with 58 atoms as is found in a-manganeseand p-chromium. F. Laves, K. Lohberg, and P. Bahlfs47 havemade a complete determination of the structure; each magnesiumatom is surrounded by 4-7 other magnesium atoms at a distance of2-95-335 d., and by 6-12 aluminium atoms at a distance of2.9-3.2 A. The aluminium atom, on the other hand, besides its8 magnesium neighbours, has 2 aluminium neighbours, one at2-82 and one a t 2.65 A.This distance is very much shorter than theA1-A1 distance of 2.86 in the metal, and indicates the extent of aspecial binding force of the aluminium, such as occurs in metallicgallium. I n the system aluminium-zinc, it appears that at hightemperatures zinc may dissolve in aluminium t o the extent of48% at 350°, but at lower temperatures this solid solution splitsup into a p, aluminium-rich, and a y, zinc-rich, portion.48 Tho41 G . Grube, H. V. Zeppelin, and H. B u m , 2. Elektrochem., 1934, 40, 143,4 2 E. Zintl and A. Schneider, ibid., 1935, 41, 764.43 Ibid., 1934,40,565; AttiR. Accad. Lincei, 1934, [vi], 19,607; A., 1934, 954.44 E. Zintl and A. Schneider, 2. Elektrochem., 1934, 40, 107.4 5 Idem, ibid., 1935, 41, 771.46 G.Koinovsky and A. Maximov, 2. Krist., 1936,92,275.4 7 Nach. Ges. Wiss. CBttingelz, 1934, 1, 67.4 8 E. Schmid and G. Wassermann, 2. Metallk., 1934, 26, 145; A., 1934,1064; E. A. Owen and J. Iba11, Phil. Nag., 1934, [vii], 17,433; A., 1934, 356.I n the Li-Mg system160; A., 1934, 591BERNAL AND WELLS : CRYSTAL CITEMISTRY. 205structure of Al,Ba 49 is of some interest. It appears to be a tetra-gonal layer lattice in which each barium atom is surrounded by16 aluminium atoms, and each of the latter is surrounded by 4 bariumand 4 or 5 aluminium atoms.The structure of gallium proposed by Laves 5O has been confirmedby Bradley.5I He finds the cell dimensions to be 4.5167, 4.5107,and 7.6448 A., the smallest known departure from tetragonalsymmetry.A.tilander 52 has studied thallium compounds extensively byelectrochemical and X-ray methods. The T1-Hg system containstwo compounds of the approximate composition Hg,Tl and HgTlswith face-centred and body-centred cubic lattices respectively.The Pb-T1 system shows an extended solid solution from lead upto 92% of thallium, with some evidence for ordered structure ofT1,Pb. The compound Bi,T1 has a very interesting structure.The cell is hexagonal, a = 5-67, c = 3.37 ,&., and contains a graphite-like arrangement of bismuth-hexagons in the holes of which, aboveand below, fit the thallium atoms. The structure of TlSb,, deter-mined by F. R. Morral and A. Westrgren,53 has a somewhat deformedcssium chloride super-lattice ; each antimony atom has four thalliumneighburs at 3.1 A., one at 3.38, and four more at 3.48 A.TheSn-As system 54 has been shown to have only one compound, SnAs,with the sodium chloride structure as with SnSb. This compoundhas, however, a range of solid solubility from 34 t o 48% (by wt.) ofarsenic. It is interesting t o note that the lattice dimensionsincrease in both directions on departing from the idea1 configuration,The structure of the alloys of the rare-earth metals has beenextended chiefly by the work of A. Rossi and his collaborators.55Two types only are found, the cubic face-centred type AB,, whereA = Pr, La, or Ce, and B = Mg, Sn, T1, or Pb, and the czesiumchloride type found €or NdAl and LaMg. Praseodymium is foundto have two structures : a-Pr, fmce-centred cubic, a = 5-10, andPPr, hexagonal elose-packed, a = 5-17, c/a = 1-633.Adamantine Compounds .-Carbides, nitrides, etc.Our knowledge of4D K. R. AndressandE. Alberti, Z.1MetallL., 1935, 27, 126.51 2. Krist., 1935, 91, 303.52 2. physikal. Chem., 1935, [A], 171, 425; 1934,168, 274; A., 1934, 724;=3 8vensk Kern. Tidskr., 1934, 46, 153; A., 1934, 1296.54 W. H. Willott and E. J. Evans, Phil. Mag., 1934, [vii], 18,114; A., 1934,953.6 5 GTazzetta, 1934, 64, 748, 774, 832, 855; A., 1935, 151, 152 ; A. RosrJi andA. Iandelli, Atti R. Accad. Lincei, 1934, [vi], 19, 415; A., 1934, 720; C. W.Stillwell and E. E. Jukkola, J . Amer. Chem. Soc., 1934, 56, 56; A . , 1934, 243.See Ann. Reports, 1933, 30, 293.2.Krist., 1934, 89, 89; A., 1934, 1301206 CRYSTALLOGRAPHY.the structure of the non-metallic carbides and nitrides has been muchadvanced by the work of M. von Stackelberg. According to him,56these structures can be most readily understood by considering themas ionic, carbon, nitrogen, etc., functioning as large anions C4-, N3-,or in higher carbides as the C> or Ck ions. These ions are in generalclose-packed, the metal ions occupying octahedral or tetrahedralholes. Thus, Be,C 57 has an antifluorite structure, each berylliumhaving four carbon neighbours, and each carbon eight berylliumneighbours.carbides with separated atoms yielding methane, those with carbonpairs, acetylene, and Mg,C,, allylene, possibly owing to C, groupsin the crystal.The structure of Li3N 59 is not, as previously supposed,6O similar tothat of ammonia; it consists of a simple hexagonal arrangement ofnitrogen atoms with lithium atoms lying, some between two and somebetween three nitrogen atoms.61 Ca3N, may have a similar struc-ture. The structure of A14@, 62 has been most fully worked out :it has a rhombohedra1 cell, a = 3-325, c = 24-94 A.; the structureis a layer one, three layers of carbon atoms being interleaved withfour of aluminium. Each of the latter is surrounded by fourcarbon atoms at a distance of 1.9-2.0 A. (sum of atomic radii,2.03 8.), while the carbon atoms have either five or six aluminiumneighbours. The closely related AI,C3N63 has a very similarhexagonal structure, a layer of A N being sandwiched between theA14C3 layers.More definitely adamantine is boron carbide, B,C,examined by F. Laves.64 L. Pauling and S. Weinbaum65 havedetermined the parameters of the framework structure B6Ca 66 andfind that each boron atom is exactly 1.716 L f . from five others.It is thebest layer lattice that we know, and the two-dimensional macro-molecules of which it is made can enter into many combinationswithout affecting its structure. That all forms of carbon exceptdiamond contain such molecules has been conclusively shown byThis classification is borne out by the action ofGraphite and its compounds have been much studied.5 6 8. physilcal. Chem., 1934, [B], 27, 53.6 7 M. von Stackelberg and F. Quatram, ibid., p. 50.68 J.Schmidt, 8. Elektrochem., 1934,40,170; A., 1934,614.59 E. Zintl and G. Brauer, ibid., 1935, 41, 102.6o R. Brill, 2. Krist., 1927, 65, 94.61 H. Hartmann and H. J. Frohlich, 8. anorg. Chem., 1934, 218, 190; A,,62 M. von Stackelberg and E. Schnorrenberg, 2. phy8ikaZ. Chem., 1934, [B],63 M. von Stackelberg and I(. F. Speiss, ibid., 1936, [A], 176,140.64 Nach. Ges. Wiss. Cfcittingen, 1934,1,67.6 5 Z. Krist., 1934, 87, 181; A., 1934, 243.6 6 See Ann. Reports, 1933, 30, 394.1934, 741.7, 37207 BERNAL AND WELLS : CRYSTAL CHEMISTRY.B. E. Warren6' by Patterson-Pourier methods (see p. 195).The finest and most amorphous carbon black is found to consist ofcrystallites about 60 8. wide by 10 A. thick, containing only twoor three layers of 400 rings each.Other work on different types ofgraphite68 confirms this, and also shows that as the particle sizediminishes, the inter-layer distance increases from 3.4 to 3.6 A.The magnetic anisotropy of graphite is even greater than has beensupposed. Indian workers 69 have shown that the principalsusceptibilities are - 22.8 and - 0.4 parallel to and perpendicularto the hexagonal axes. U. Hofmann 70 has given a general surveyof the reactions of graphite; in particular, of the formation ofgraphite oxide by the addition of oxygen atoms (probably hydroxy-groups) on each side of the molecule. A series of graphite sulphateshas also been prepared 71 with sulphate groups between every two,four, six, etc., graphite planes. Carbon subfluoride, CF, is also agraphite compound which has largely lost its metallic character.72Iodides, phosphides, etc.The iodides and mercuri-iodides ofsilver and copper have proved to be of great theoretical interest(see p. 188). The p- and the y-form of silver iodide, stablebetween 146-136" and below 135", have zinc blende and wurtzitestructures respectively, with densities 5.71, and 5.69,.73 They maybe considered as close-packed iodine lattices with metal atoms intetrahedral interstices. The a-form, investigated by L. W. Strock,74has a body-centred cell, a = 5.034 A., with a density of 6.00 andtwo molecules per cell. The silver atoms cannot be placed; theyare, so to speak, in a gaseous state between the iodine atoms. Thisstructure goes far t o explain the large self-diffusion, electric con-ductivity, and plasticity of the crystals, but the structure is soanomalous that it calls for further physical and crystallographicinvestigation. A similar but less marked indeterminacy has beenfound in the cubic (> 90") modification of silver and cuprous mercuri-6 7 J .Chem. Physics, 1934, 2, 551 ; A., 1934, 1160.6 8 P. C. Mukherjee, 2. Physik, 1934,88, 247; A., 1934, 577; M. Miwa, Sci.Rep. Tdhoku Imp. Univ., 1934,23,242 ; A., 1934, 835 ; W. S. Wesselowski andK. W. Wassiliew, 2. Krist., 1934, 89, 156.69 K. S . Krishnan, Nature, 1934, 133, 174; B. C. Guha and B. P. Ray,Indian J. Physics, 1934,8,345.70 Kolloid-Z., 1934, 69, 351 ; A., 1935, 163 ; U. Hofmann, A. Frenzel, andE. Csal&n, Annalen, 1934,510,l; A., 1934, 614; cf.H. Thiele, 2. Elektrochem..1934, 40,26; A., 1934, 262.7 1 A. Frenzel and U. Hofmann, ibid., p. 511 ; A., 1934, 978.72 0. Ruff and 0. Bretschneider (with F. Ebert), 2. anorg. Chem., 1934,217,73 N. H. Kolkmeijer and J. W. A. van Hengel, 2. Krist., 1934, 88, 317; A.,74 2. physikal. Chem., 1934, [B], 25, 441 ; A., 1934, 834.1 ; A., 1934, 378.1934, 1161 ; L. Helmholz, J . Chem. Physics, 1935, 3, 740208 CBYSTALLOGIRAPHY.iodides studied by J. A. A. Ketelaar : 7 5 s 76 neither mercury nor silveratoms are in fixed positions in the cubic close-packed iodine lattice.The structures of a number of phosphides and arsenides havebeen determined by M. von Stackelberg and R. Paulus.77 Zn3P,,Zn3As,, Cd3P,, and Cd,As, have not, as was previously supposed, acubic, but a tetragonal pseudo-cubic, structure in which the metalatoms fit in the tetrahedral holes of a slightly deformed cubic closepacking.ZnP,, CdP,, and ZnAs, have more complicated tetragonalstructures. The structures of Cu,Sb and Fe,As are identical ; theymay be considered as layers of cubic close-packed CuSb, Cu2, CuSbheld together by attractions between the copper in one layer and theantimony in the next.78 The monophosphides and arsenides of Mn,Fe, Co '9 are shown to have a modified NiAs structure, while FeP,has a marcasite structure.*0The work of the past two years hashelped to confirm and extend the general classification put forwardin the Report for 1933 (p. 398). W. Hofmanngl has studied, inparticular, the sulphaiitimonatcs, and shown that where the ratioSb : S < 1 : 3, there is a tendency t o form fibrous crystals with achain period 3 0 8 4 .3 A. corresponding to the chain molecules s s sSulphides and sulpho-salts.s s sThere is a general tendency for antimony to have three close sulphurneighbours, copper four, and lead six.A. Ferrari has shown that the series, sclericlase PbAs,S, to dufres-noyite Pb&ssS5, is isomorphous and shows a strong resemblance toorpiment As,S, and to wolfsbergite CuSbS,.fj2 Many more sulphidesare found t o be related to the zinc blende 4-co-ordination type.Binnite (Cu ,Fe)12As4S13, analysed by L. Pauling and E . W. Neuman,83may be taken as the type of the tetrahedrite minerals; here again,the arsenic atoms are attached to 3 sulphur atoms only.Colusite(Cu, Fe, Mo, Sn),(S, As, Te),-484 has a statistical zinc blende76 2. Krist., 1934, 87, 436; A., 1934, 947.76 2. physikal. Chem., 1934, [B], 26,327 ; 1935,30,53.7 7 Ibid., 28, 427.78 E. Elander, G. HLigg, and A. Westgren, Arkiv Kemi, Min. Geol., 1935,79 K. E. Fylking, ibid., 1934,11, [B], 48.80 K. Meisel, 2. anorg. Chem., 1934,218, 360; A., 1934, 947.81 2. Krist., 1935, 92, 161.82 A. Ferrari and R. Curti, Per. Min., 1934, 5, 3.O3 2. Krist., 1934, 88, 54; A., 1934, 1060.84 W. H. Zachariasen, Amer. Min., 1933, 18, 534; A., 1934, 720.12, [B], 1BERNAL AND WELLS : CRYSTAL CHEMISTRY. 209structure. Stannite, Cu,FeSnS4,85 belongs to the chalcopyritetype, while enargite, Cu,AsS4,*6 is more closely related to wurtzitebut contains separate ASS, groups.Tetradymite, Bi,Te,S,87 has avery interesting structure with successive layers of S-Bi-Te-Te-Bi-Sall in 6-co-ordination, For other sulphides examined, only refer-ences can be given.** Silicon disulphide has a structure of a newtype. W. Bussem, €3. Fischer, and E. Gruner 89 have found that > Si/'\si \s/ <:x:>i<it contains chains of tetrahedra sharing pairs of sulphur atomsand not a three-dimensional network as in SiO,.Ionic Compounds.-Halides. E. Zintl and A. Harder Q0 have com-pared the structures of LiHl and LiH2, the respective latticedimensions being 4.085 and 4-065 & 0.001 8. This means thatthe radius of the hydrogen ion is changed from 1.27 to 1-26, or0.8% effectively, by the lower zero-point energy of deuterium.They 9 l have further examined tho hydrides of calcium, strontiumand barium, and shown that these possess a pseudohexagonalstructure intermediate between a CaF, and a layer lattice.Eachstrontium ion has three hydrogen neighbours at 2.35 and four at2.71 A. (sum of ionic radii, 2.52 A.).E. B. Thomas and L. 5. Wood 92 have examined the reactionsbetween alkali halide pairs. In every case but two, the final productcontains the pair with the smallest radius sum and therefore withthe largest lattice energy, e.g., NaBr + KC1 --+ NaCl + KBr.In the two cases indeterminate, ICBr + RbI and RbCl + CsBr,homogeneous solid solutions are formed.Although calcium chloride has a slightly deformed rutile struc-ture,gs the halides of the other bivalent elements cadmium, cobalt,and nickel have been shown 94 to have either the cadmium chloride85 L.0. Brockway, Z. Krist., 1934, 89, 434; A., 1935, 152.86 L. Pauling and S . Weinbaum, ibid., 88,48; A., 1934, 1060.D. Harker, ibid., 89, 175.M. J. Buerger, Amer. Min., 1935, 20, 36; A., 323; F. Weibke and J.Laar (with K. Meisel), 2. anorg. Chem., 1935, 224, 49; A., 1322; G. R. Leviand A. Baroni, 2. Krist., 1935,92,210 ; B. Gossner and 0. Kraus, Centr. Min.,1934, [A], 1, 1 ; B. Gossner, ibid., 1935, [A], 11, 321.Naturwiss., 1935, 23, 740.90 2. physikal. Chem., 1936, [B], 28, 478.91 Z. Elektrochem., 1935,41, 33.92 J . Amer. Chem. SOC., 1935,57,582; A., 832; 1934,56,92; A., 1935, 265.93 A. K. Van Bever and W.Nieuwenkamp, 2. Krist., 1936, 90, 374.94 J. M. Bijvoet and W. Nieuwenkamp, ibid., 1933, 86, 466; A., 1934, 16;J. A. A. Ketelsar, ibid., 1934, 88, 26; A., 1934, 1060; H. Grime and J. A.Santos, ibid., p. 136; A., 1934, 1161210 CRYSTALLOGRAPHY.or the cadmium iodide structure or to alternate between them (seep. 188). G. Bruni and A. Ferrari95 have discussed the extendedisomorphism of halide crystals based on close packed halogenions.96 Parallel intergrowths have been found between potassiumand lead chlorides.97H. Braekken and W. Scholten 98 have determined the structureof mercuric chloride. It is a fairly definite molecular lattice witha trace of ldyer formation, but along (120) and not along (OOl), asin mercuric bromide. The mercury halides are a good example ofthe transition from a purely ionic type, HgF,, to a molecular typeHgCl,, and through a molecular layer lattice, HgBr,, to a true layerlattice HgI,,gQ with increasing polarisability of the anion.F.A. Bannister and M. H. Hey have shown that the structureof matlockite, PbFCl,, and of PbFBr is a type structure foroxyhalides-such as BiOCl(Br,I), and probably others such asFeOC1.E. Zintl, A. Harder, and B. Dauth 3 have exam-ined the compounds (Li,Na,K),(O,S,Se,Te). All crystallise withthe fluorite structure, but there are considerable variations fromaccepted ionic radii. (Mlle.) B. Riihemann 4 has shown that thethermal anomaly of manganese oxide a t - 115" to - 119" isaccompanied by a change of lattice constant from 4.426 to 4.416.Similar anomalies have been reported for FeO and Fe,04, wherethey are accompanied by magnetic changes.These changes,though similar to those produced by rotation of molecules, are hereprobably due to electronic changes in the unfilled electron levels ofiron and manganese. Palladous oxide has been shown to have4-square co-ordination like its sulphide.5 The structure of cupricoxide, tenorite,6 is a distorted monoclinic variety of the samestructure : each copper atom is surrounded by 4 oxygen atoms in arectangle, Cu-0 = 1-95. Another form is reported.'Considerable dispute between electron and X-ray methodshas arisen over the lattice dimension of zinc oxide. G. I. FinchSimple oxides.95 2. Krist., 1934, 89, 499.g6 See Ann. Reports, 1931, 28, 285.9 7 M.Mehmel and W. Nespital, Z. Krist., 1934, 88, 345; A., 1934, 1161.g8 Ibid., 89, 448.D9 W. S. Gorski, Physikal. 2. Sovietunion, 1934, 5, 367 ; P. Joliboia and G.Fouretier, Compt. rend., 1933, 191, 1322 ; A., 1934, 41.Min. Mag., 1934,23,587 ; 1935,24,49 ; A., 1934, 1197.See Ann. Reports, 1933, 30,, 399.2. Elektrochem., 1934, 40, 588.Physikal. 2. Sovietunion, 1935, 7, 590; A., 1307.See Ann. Reports, 1933, 30, 396.G. Tunell, E. Posnjak, and C. J. Ksands, 2. Krist., 1935, 90, 120.C. A. Murison, PhiE. Mag., 1934, [vii], 17, 96; A., 1934, 134RERNAL AND WELLS : CRYSTAL CHEMISTRY. 21 1and H. Wilman 8 find by electrons, a = 3.258, c = 5.239, & 0.005 A.,whereas C. W. Bunn finds by X-rays a = 3.2426 &- 0.0001,c = 5.1948 & 0*0003 A.9 This apparent discrepancy may be dueto the dispersion of the electron waves, but another cause hasrecently been shown by V.E. Cosslett 10 to be that the dimensionsof zinc oxide prepared as smoke vary with time, a changing from3.234 to 3.279, and c from 5.221 to 5.367 in 18 months owing to slowrelief of quenching strain.G. Hagg l1 has studied the properties of thecubic tungsten bronzes Na1-o.3WO3.12 They may be consideredas interstitial solutions of Na in WO, or as solid solutions ofNa+WS+O, in WefO,. All have a sub-metallic character (surfacecolour, conductivity decreasing with temperature) which becomesmore marked as the percentage of sodium falls; when Na : W <0.3 : I, the amount of Na is not sufficient to stabilise the open cubicstructure and it becomes tetragonal, exactly as in the correspondingcase of the silicates ultramarine 13 and sodalite.l4 Correspondingsuboxides of tungsten, WSO,, and W4011, have been examined;15they may be, however, hydrogen bronzes H05WO3 and H025W03.The &,O, system also shows continuous variations of structureson taking up and losing oxygen.I6 Mn,03 exists in two forms,P-Mn203, bixbyite C type, and cc-Mn203, probably related toMn,O4 as y-Fe,O, is to Fe,O,.Nd,O, and La,03 l 7 have now beenprepared of the C (cubic) type.E. J. W. Verwey 18 has specially studied the y-Fe,O, and y-Al,O,structures. The relation of these to the spinels has been studiedby E. J. W. Verwey,l8 G. H&gg,lg E. Kordes,Z0 and others.2l It hasbeen shown, from considerations both of atomic dimensions and ofComplex oxides.* J., 1934, 751; A., 1934, 835.Proc.Physical SOC., 1935, 47, 835; A., 1307.lo Nature, 1935, 136, 988.l1 2. physikal. Chem., 1935, [B], 29, 192; Nature, 1935,135, 874.l2 See Ann. Reports, 1933, 30, 400.l3 F. M. Jaeger, Bull. SOC. frang. Min., 1930, 53, 183.l4 T. F. Barth, 2. Krist., 1932, 83, 606.l5 F. Ebert and H. Flasch, 2. anorg. Chem., 1934, 217, 95; A., 1934, 378.l6 P. Dubois, Compt. rend., 1934, 199, 1416; A., 1935, 181; M. Le Blancl7 K. Lohberg, ibid., 1935, [B], 28, 402.18 J . Uhem. Physics, 1935, 3, 592; A., 1307; 2. Krist., 1935, 91, 65, 317;l9 2. physikal. Chem., 1935, [B], 29, 95 ; G. Hligg and G. Soderholm, ibid.,2o Ibid., 91, 193 ; 92, 139.21 G.L. Clark, E. E. Howe, and A. E. Badger, J . Amer. Cemm. SOC., 1934,and G. Wehner, 2. phyaikal. Chem., 1934, [A], 168, 59; A., 1934,378.E. J. W. Verwey and M. G. van Bruggsr, ibid., 92,136.p. 88.17,7 ; A., 1934,249212 CRYSTALLOGRAPHY.intensities, that the previously assumed oxygen addition 22 to thecell is incorrect, and that, instead, there are 21Q cations distributedstatistically over the 24 (8 tetrahedral and 16 octahedral) vacantpositions in the cell. Small quantities of lithium stabilise thisstructure as LiAl,08 20 in the limit. The y’-Al,O, formed by surfaceoxidation is an even more statistical structure with the sameoxygen arrangement ; the 213 aluminium atoms occupy 32 positions,or in the reduced cell which results, 28 atoms occupy the 4 positionsof the rock salt lattice.A similar structure, but with Li& andTi$t ions instead of Alii is that of Li,Ti0,,20 which is fully misciblewith MgO and LiFeO, (see p. 188).E. Posnjak and T. F. W. Barth23 have studied the hardly lessextended haematite(Fe,O,)-ilmenite(FeTi0,) series. These areshown to be strictly isomorphous, as are the titanates of Mg, Mn, Co,Ni, and Cd (low-temperature form). The high-temperature formof CdTiO, belongs to the perovskite type, which has also verymany members.24Hydroxides. The past two years have shown great advances inour knowledge of the hydr0xides.2~ As the numbers of structuresanalysed increased, the function of the hydrogen in binding togetherthe hydroxy-groups attached to different cations was more fullyrecognised. J.D. Bernal and (Miss) H. D. Megaw26 have sum-marised our knowledge on this point in a paper where all knownhydroxide structures are discussed. It is found that the hydroxylgroup varies in a continuous way from a quasi-isotropic group inalkali hydroxides t o a definitely tetrahedral, water-like, group inthe neutral and slightly acid hydroxides. The increasing polarisingpower of the cation drives the proton further from its own oxygennucleus, and consequently increases its attraction for the negativeregions in other hydroxyl groups. In this way, a bond, which maybe called the hydroxyl bond, is formed, only leas in strength than thehydrogen bond in acids (as shown by the 0-0 distance of 2.76instead of 2-55 8.as in acids). By the use of this conception, it hasbeen possible to locate the positions of hydrogen atoms in a numberof hydroxide structures, particularly in hydrargilltite 27 where thesix hydroxyla of different Al(OH), groups form an irregular trigonalprism, six of whose sides, of length 2-78, 2.80, 2-82, and 2.94, 2.98,3.10 B., represent hydroxyl bonds, while the remaining three, ofes See Ann. Reports, 1933,30, 403.23 2. Krist., 1934, 88,265, 271 ; A., 1934, 1162.24 A, Haffmam, 2. physiEaE. C h m . , 1935, [B], 28, 65; H. Rheinboldt, J .25 Cf. Ann. Reports, 1933, 30, 401.87 (Miss) H. D. Megaw, 2. Krist., 1934, 87, 185; A., 1934, 352.pr. Chem., 1934, [ii], 139, 318; A., 1934, 587.Prm. Rmj. Sac., 1935, [A], 151, 384; A., 1307BERNAL AND WELLS : (3RYSTAL CHEMISTRY.213length 3.32, 3.38, and 3*46A., do not. Linking up of hydroxylbonds explains the properties of the gels formed by neutral hydr-oxides, discussed from the structural point of view by R. Fricke.28The structure of boric acid has been completely determined byW. H. Zachariasen.29 It consists of flat layers of BO, groupsattached to each other by hydrogen or hydroxyl bonds, the 0-0distance, 2.71, being nearer the requirements of the latter. Thelayers adhere by residual forces at a distance of 3-18 A., agreeingwith the cleavage and softness of the crystals. The hydratedboron phosphate, B( OH),, (HO),PO may have a very similar struc-ture.30Telluric acid is also a hydroxy-acid, Te(OH),; its structure hasbeen studied by B.Gossner and 0. Kraus and by L. Pauling.32In its two cubic and monoclinic (pseudocubic) forms it representsTe(0H) octahedra bound together in different ways by hydroxylbonds of length 2.76 8. Recent work on zinc hydroxide 33 shows thatthe different reported crystalline forms have all the same structure.34The oxy-hydroxide, BO(OH), has a definite crystalline form 35but its structure has not been determined. The structures ofM- and y-Al(Fe)O(OH), diaspore (goethite) and bohmite (lepido-crocite), have been determined by S. Goldsztaub 3, md F. J.Ewing.37 Both contain hydroxyl bonds, but whereas the a-formsare fairly compact, the y-forms are true layer lattices of the typeof the oxychlorides (see p. 210). The calcium aluminates formcomplex hydrates and hydroxy-compounds.3* The structure ofone of these, hydrocalumite,39 Ca,Al( OH) ,,3H,O, has been partiallyanalysed; it consists of alternate layers of A1(OH),2H20 andCa2H20.The chief interest with silicate investig-ations in the past two years has been concerned with those silicatesBorates and silicates.28 Kolloid-Z., 1934, 69, 312; A., 1935, 162.29 2.Krist., 1934, 88, 150; A., 1934, 1161.30 E. Gruner, 2. anorg. Chem., 1934,219, 181; A., 1934, 1081.3L 2. Krist., 1934, 88, 298; A., 1934, 2161.aa Ibid., 1935, 91, 367.33 K. Petrescov, ibid., p. 505; (Miss) H. 1). Megaw, ibid., 1935, 90,34 Ses Ann. Reports, 1933, 30, 401.36 H. Menzel, H. Schulz, and H. Deckert, 2. anorg. C'hern., 1934,220,49.36 Bull. SOC. f r a v .Min., 1935, 58, 6.37 J . Chem. Physics, 1935, 3, 203; cf. M. Deflandre, Bull. Sac. fra%. Min.,1932,55,140; K. Takane, Proc. Imp. Aliad. Tokyo, 1933,9,113; F. J. Ewing,J . Chern. Physics, 1934, 3,420.283.3 8 R. Salmoni, Qazzetta, 1935, 64, 519.39 C. E. Tilley [with (Miss) H. D. Megttw and M. H. Hey], Min. Mag., 1934,23, 607; A., 1934, 1197214 CRYSTALLOURAPHY.with extended three- and two-dimensional structures, i.e., withsilica in its various forms, with zeolites, and the clay minerals. NOWthat the main outline of silicate structure is known, its utility isbeing appreciated in the technical sphere ; particularly in America,much work is being done on X-ray structures in connexion with theglass and ceramic industries, which involves not only the study ofthose silicates but of the analogous boron compounds which alsoform extended frame-work structures.N. W. Taylor and S. S.Cole 40 have succeeded in producing crystalline B,O,, hithertoknown only as a glass, by careful dehydration of H,BO,. It appearsto be cubic, a = 10.04, with 16 molecules per cell, but its exactstructure is not known. It melts at 294" &- 1" to a very viscousliquid which hardens to glass at 276". On melting, there is anincrease in density from 1.805 to 1.844, showing that, like ice, butunlike silica, the arrangement of the solid has a lower effectiveco-ordination than that of the liquid.A study of the borates 4 1 shows that, like t'he silicates, the extendednetworks and chains may be found; but no complete structureshave been worked out.M. Mehmel 42 has made an elaborate studyof boracite, Mg6C1,B,4026, which above 265" is cubic, a = 12-1 8.,and below, rhombic, pseudo-cubic; but the exact structure has notbeen determined-it is apparently also of a, framework character.The structure of jeremejewite, BA18,,43 has been studied but provesto be unexpectedly complex. The structures of the phosphates andarsenates of boron, aluminium, and iron, as Goldschmidt predicted,are similar to those of silica. BPO, and BAsO,~, have a cristo-balite structure with both atoms tetrahedrally surrounded byoxygen. M. Strada4j maintains that AlPO, and AlAsO, havethe same structure. El. F. Huttenlocher 46 and F. Machatschki 47have, however, shown that normally they are of the quartz type witha doubled c axis on account of the difference of the two atoms re-placing silicon, v.Caglioti 48 has shown that FePO, has the samestructure, but the AlBO, may be dimorphous with the high-temper-ature cristobalite type, thus reconciling all the other workers' results.T. F. W. Barth49 has gone further, and shown the aluminites and40 J . Arner. Chern. SOC., 1934,56, 1648 ; A., 1934, 947 ; J . Arner. Ceram. Soc.,4 1 S. S. Cole, N. W. Taylor, and S. R. Scholes, ibid., p. 79; S. S. Cole, S. R.42 2. Krist., 1934, 87, 239; 88, 1 ; A., 1934, 387, 1060.43 B. Gossner and 0. Kraus, Centr. Min., 1934, [A], 11, 348.41 G. E. R. Schulze, 2. physikal. Chem., 1934, [B], 24,215 ; A., 1934,352.45 Gazzetta, 1934, 64, 653; A., 1934, 1296.46 2.Krist., 1935, 90,508; A., 1194.48 Atti R. Accad. Lincei, 1935, 22, 146.1935,18,55.Scholes, and C. R. Amberg, ibid., p. 58.4 7 Ibid., p. 314; A., 1060.49 J . Chem. Physics, 1935, 3, 323BERNAL AND WELLS : CRYSTAL CHEMISTRY. 21 5ferrites, K,AI,O, and (K2, Rb,, Pb)(Fe20,), also to be of the cristo-balite type with the large atoms in the interstices as in ~ a r n e g e i t e . ~ ~M. J. Buerger has discussed the stability fields for the differentforms of SiO,.51 The three forms, quartz, tridymite, and cristo-balite, have increasingly empty spaces in the structure; con-sequently, the addition of foreign atoms with appropriate siliconsubstitutions has the effect of stabilising the higher-temperatureforms. The general formula for such silicates can be writtenWhere M represents the atom substituting the silicon, usually AP,and Q* is the interstitial atom, usually Nali or Ca2+.When n = 1,the tridymite structure, and when 12 = 2 the cristobalite structure, i8stable at room temperatures.A detailed analysis of low cristobalite structures has been made byW. Nieuwenkamp; 52 the Si-0-Si angle is found to be 150". P'ei-Hsiu Wei,54 in a redetermination of the a-quartz structure, foundit to be 144". Very interesting two-dimensional crystals of cristo-balite, consisting essentially of polysynthetic twins, have beendescribed as pseudomorphs of t r i d ~ m i t e , ~ ~ the (111) plane of thecristobalite corresponding in different positions to the (0081) planeof the latter. Further work has been done on the formation ofcristobalite and the coagulation of silica gels.55B.E. Warren has made a very thorough study of the structure ofsilica and other glasses by means of X-ray~.~G The new methodsof crystal analysis (see p. 195) make it possible to determinethe relative statistical position of the silicon, oxygen, and otheratoms. The glasses of SiO,, GeO,, BeF, give essentially the samepattern. The silicon atom has six tetrahedral oxygens at 1.60, fourmore silicon neighbours a t 3.20, and twelve more SiO, groups at5.20 d. I n the case of the soda glasses, a certain number of oxygenatoms are attached to only one silicon atom, but to several sodiumatoms, each of which has on the average two oxygen neighbours at2.35 and two silicons a t 3.45 8.50 See Ann.Reports, 1933, 30, 406.51 2. Krist., 1935, 90, 186.53 Ibid., 90, 377.5 5 F. P. Dmyer and D. P. Mellor, J . Proc. Roy. SOC. N.S. W., 1934, 68, 47;A., 1935, 324; 67, 420; A., 1934. 947; M. 0. Charmandarian and V. K.Markov, Ukrain. C'hem. J., 1933, 8, 1; A., 1244.66 Physical Rev., 1934, [ii], 45, 657 ; A., 1934, 834; B. E. Warren and C. F.Hill, 2. Kyist., 1934,89,481; B. E. Warren and A. D. Loring, J . A ~ w . Ceram.SOC., 1935, 18, 269; A., 1308; cf. H. Hollenweger and H. Rumpett, Angew.Chem., 1933, 46, 662; A., 1933, 1247.52 Ibid., 92, 82.54 Ibid., 92, 355216 CRYSTALLQQRAPHY.EIectron diffraction has also been applied to the study of glasses.57N. A. Schischakov has obtained the rather surprising result that veryfinely powdered silica, glass shows sharp lines, indicating eitherthe presence of small crystals of cristobalite in normal glass, or moreprobably, the rapid devitrification of glass when ground to a finepowder.Structural work on the felspars has been c o n t i n ~ e d .~ ~ The san-idine type 69 is found to hold for the K-Ba felspars. The albite-anorthite series (NaA1Si,08 --+ CaA1,Si,Os) show a doubling of theunit cell when the number of calcium atoms is greater than that ofsodium.The structure of the zeolites has been particularly well studiedwith special relation t o their base-exchange properties ; a generalpicture of them is given in an important paper by W. H. Taylor.60The mode of binding the unattached cations and the water mole-cules is discussed, and it is found possible to place the water mole-cules in such a way as to specify the tetrahedral positive and negativelinkings postulated by Bernal and Fowler.61 J.Wyart 62 has deter-mined the structure of cliabazite and other zeolites, and an importantseries of papers has been produced by F. A. Bannister and M. H.Hey 63 correlating the chemical and structural properties of thezeolites. The deformed Al-Si framework of the structures ofhauyn and nosean, Na[A1,Si60,,]804, has been studied byMachatschki.64Clay Ji!ineruZs.-The structure of the clay minerals has excitedmuch interest, both scientific and technical, in connexion withceramics and soils. A general account of the X-ray work is givenby U. Hofmann,64a and a more popular historical survey by C.E.Marshall. 65 Owing to the fine-grained nature of clays, the problemoffers great difficulties, but X-ray methods have succeeded a t leastin ordering an apparently bewildering mass of data.J. W. Gruner 66 R. C. Ma~Murchy,~~ M. Mehmel,6s and57 N. A. Schischakov, Nature, 1935, 136, 514; A., 1309; K. R. Dixit,58 W. H. Taylor, J. A. Darbyshire, and H. Strunz, 2. Krist., 1934, 87, 464;59 See Ann Reports, 1933, 30, 405.6o Proc. Roy. SOC., 1934, [ A ] , 145, 80; A., 1934, 947.61 See Ann. Reports, 1934, 31, 42.62 Bull. Soc. franc. Min., 1933, 56, 81; A., 1934, 1197.Physilcal. Z., 1934, 35, 141; A., 1934, 352.p., 1934, 947.Min. Mag., 1933, 23, 421; 1934, 23, 483, 556; A., 1934, 167, 508, 882;64 Centr.Min., 1934, [A], 5, 136.6 5 Science Progress, 1936, [v], 30, 422.66 2. Krist., 1934,88,412; A,, 1934, 1162; Arner. Min., 1934,19,557; A,,13? 2. Krist., 1934, 88, 420; A., 1934, 1162.1935,24,99; A., 1345.See ref. (70), p. 207.1934, 841 ; 1935,20,475; A., 1345.6 8 Ibid., 1935, 90, 53BERNAL AND WELLS : CRYSTAL CHEMISTRY. 217others 69 have made more or less complete structure analyses. Thereare roughly three series of clay minerals containing treble, double,and single (SiAl),O, and Al,Mg,(OH), hexagonal layers. They differfrom the micas in that the layers are electrically neutral and arejoined only by hydroxyl bonds. The treble series is represented bytalc and pyrophyllite, with two Si,Os layers on either side ofMg,(OH), layer (talc) or A1,(OH)6 layer (pyrophyllite).Theformula may be written (indicating layers in turn by brackets)(O,)Si( 0,OH) ($$ (O,OH)Si(O,). By intercalating an indefinite3amount of water between such layers, the bentonite-thixotropicminerals are formed, montmorillonite (Mg), beidellite (Al), andnontronite (Fe3+). The double series has a Si,06 layer on one sideonly of the Al,(OH), layer. It is represented by kaolinite,(O,)Si( 0,0H)Al,(OH)3, and also by nacrite, dickite, and meta-halloysite, which differ only in relative positions of the layers.The single-layer clays are represented by halloysite, which hasalternate silica alumina sheets joined by hydroxyl bonds,here also water can enter between the layers.Optical and chemical research is keeping pace with the X-ray~tudies.7~ The formulze of the minerals have been recalc~lated,~~and the main types, kaolinite, dickite, and montmorillonite, spthes-ised by R.H. Ewe11 and H. Insley 72 by heating co-precipitatedhydrogels under high pressure.The cyanide ion inAgCN does not rotate as it does in KCN,', but as C. D. West 74has shown, it forms a unique linear lattice Ag-CN-Ag-CN in whichthere is considerable freedom of motion along the lines. TheAg-Ag distance is only 5.26 8., so it is possible for Ag to be co-ordjnately linked to the CN group at either end. The peroxide ion,Oi', has been studied in the tetragonal SrO, and BaO,, isomorphouswith CaC2.75 The 0-0 distance is 1.31 (Psuling theoretical, 1.32;in persulphate, 1.46). The CNS group 7G is found to be bent c t t an69 B.Gossner, Celztr. Min., 1935, [A], 7, 195; G. Nagelschmidt, 2. Krist.,70 C. S . Ross and P. F. Kerr, U.S. Geol. Survey, 1934, Prof. Paper 186-G,71 J. Holzner, Chem. Erde, 1935,9,464; A., 1220; C. E. Marshall, 2. Krist.,72 J . Res. Nat. Bur. Stand., 1935,15, 173; A., 1333.73 See Ann. Reports, 1931, 28, 295.74 2. Krist., 1934, 88, 173; 1935, 90, 555; A., 1194.7 5 J. D. Bernal, E. Djatlowa, I. Razarnowsky, 8. Reichstun, and A. G.'6 W. Biiesem, P. Gunther, and R. Tubin, 2. physibal. Chsm., 1934, [B],. . . (0,)SiOH . . . (OH),AI,( OH), . . . . ;Complex Ions.-Diatomic and linear ions.1934, $7,120; A., 1934, 274.135; A., 1935, 322; C. E. Marshall, 2. Krist., 1935, 90, 8.1935, 91, 433.Ward, ibid., 1936,92,344.24,l; A., 1934,243218 CRYSTALLOGRAPHY.angle of 130°, but the results are not conclusive.The I,’ group ofNH41, has been carefully studied by R. C. L. Mooney ; 77 it is practic-ally straight but unsymmetrical, 1-1 distances being 3.10 and 2.82,a small but probably real difference. The 1-1 distance in differentmolecules is 4 - 1 4 - 2 8 and NH,-I 3-7 A. W. H. Zachariasen andMooney ‘8 have determined the structure of the hypophosphitegroup H2P0,; it is a distorted tetrahedron with oxygen a t twocorners and hydrogen at the others ; the 0-P-0 angle is 120”.The structure of sodium hydrogen carbonate has alsobeen determined by Zachariasen.79 The CO, groups are linkedin endless chains by a hydrogen bond of length 2.55 A. Czesium ni-trate 8o has a pseudo-cubic structure resembling CsIand KIO,.WhenNO,‘ ions are not parallel or are rotating, they behave as if they weresimple ions about equivalent to 1’, as also do the ClO,‘, MnO,‘ ions.and BeF,” 82 ions have been proved iso-morphous with the C10,’ and SO4” ions. Ce,(W04)3 83 has ascheelite, CaWO,, structure with cerium atoms statistically distri-buted. Na6(S0,),C1F, sulphohalite, is shown by A. Pabst 84 tohave an extremely compact cubic structure with SO, groups in thecube centre, C1 and F alternately a t the corners, and Na atomsmid-way along the edges.The structures of a large number of hexafluoro- andhexachloro-salts have been determined,85 but in every case theyconfirm the octahedral character of the group. The ions OsO2C1,” 86and QsNCl,” 87 also appear to be octahedral, the first in trans-configuration.L.Pauling, H. P. Mug, and A. N. Winchell 88 have shown thatswedenborgite, NaBe4Sb07, does not contain an SbO, group butconsists of SbO, groups and Be40 groups as in basic beryllium acet-AX, ions.AX, ions. The BF,’AX, ions.7 7 2. Krist., 1935, 90, 143.78 J . Chem. Physics, 1934, 2, 34; A., 1934, 243.79 Ibid., 1933,1,634; A., 1934, 16.81 J. L. Hoard and V. Blair, J. Amer. Chem. Soc., 1935, 57, 1985.82 P. L. Mukherjee, Current Sci., 1934,3,66; A., 1934, 1162; R. Hultgren,2. Krist., 1934, 88, 233; A., 1934, 1162; J. L. Hoard and V. Blair, J . Amer.Chem. SOC., 1935, 57, 1985.L. Waldbauer and D. C. McCann, ibid., 1934, 2, 615; A., 1934, 1161.83 J. Beintema, Proc.K. Alcad. Wetensch. Amsterdam, 1935, 38, 1011.8 6 B. Gossner and 0. Kraus, ibid., 88, 223 ; A., 1934, 1161 ; J. A. A. Kete-laar, ibid., 1935, 92, 155; R. B. Corey, ibid., 1934, 89, 10; R. B. Corey andIt. W. G. Wyckoff, ibid., p. 469; G. Engel, ibid., 1935,90,341; J. L. Hoard andL. Goldstein, J . Chem. Physics, 1935, 3, 645.8 6 J. L. Hoard and J. D. Grenko, 2. Krist., 1934, 87, 100; A., 1934, 2.43.8 8 Amer. Min., 1935, 20, 492; A., 1308.2. Krist., 1934, 89, 514.J. Verhulst, Bull. SOC. chim. Belg., 1933, 42, 359; A., 1933, 1235BERNAL AND WELLS : CRYSTAL CIIEMISTEY. 210ate.89 NaSb(OH),,W though tetragonal, a = 8.00, c 5 7.86, hasessentially a sodium chloride structure of Na’ and Sb(OH),’ ionsbound together in a face-centred ciibic array by hydroxyl bonds asin Te(OK),, a = 7.83 (see p.213).G. R. Levi and G. Peyronel 91 havestudied the cubic salts (Si, Ti, Zr, Sn, Hf)P,07 and have establishedthe fact that the P&- ion consists of two tetrahedra with a commoncorner and possessing the symmetry 3, trigonal axis. The strongeffects of the quadrivalent ions ma,y be in part responsible for thisregularity. It would be interesting to see what the structure of theP,07 ion would be in an alkali pyrophosphate. The trithionate ion(S,O,)2- is essentially, according to W. H. Zachariasen,92 a pyro-ionin which the linking is done through a sulphur atom (see Fig. 3).The ion has one plane of symmetry through the three sulphur atoms,FIG. 3. FIU. 4.Pyro-, per-, and poly-ions.‘ \esulphuP.0 oxyg&n.Structure of trithionate radical. Structure of persulphate group.and a pseudo-plane perpendicular t o it. The S-S distance is 2-15 A.and the S-S-S angle 103”.The per-ions differ from the pyro-ions in that their oxygen atomsare joined, not shared. Zachariasen and his co-workersg3 havemade a careful study with Fourier analyses of the persulphate ionin the ammonium, potassium, arid caesium salts. The two SO,groups are joined somewhat askew (Fig. 4). The link between themis somewhat longer than the theorotical value 1.31, but the accuracyclaimed is $: 0.15 A.The ions Tl,Cl,”‘ 94 and WZCl9”’ 95 appear to be isomorphous,8g L. Pauling and J. Sherman, Proc. Nat. Acad. Xci., 1934,20,336.go J. Beintema, Proc. R. Alcud. Wetensch.Amsterdam, 1935, 38, 1015.91 2. Krist., 1935, 92, 190.g2 J . Chm. Physics, 1934, 2, 109; A., 1934, 479; 2. Krist., 1934, 89, 529.93 R. C. L. Mooney and W. H. Zachariasen, Physical Rev., 1933, [GI, 44,327 ;A., 1935, 152; 2. Krist., 1934, 88, 63; A., 1934, 1060; R. C. Keen, ibid., 1935,91, 129.94 J. L. Hoard and L. Goldstein, J. Chem. Physics, 1935, 3, 199; H. M.Powell and A. F. Wells, J., 1935, 1008.95 C. Brosset, Nature, 1935, 135, 874; Arkiv Kemi, Min. Qeol., 1935, 12,1441, 1220 CRYSTALLOURAPHY.with a pair of metal atoms surrounded by octahedra of chlorineatoms which share one face. Cs,As,CI, 96 does not, however, con-tain the ion As,CI,, but should be written (CsCl),(AsCI,),.The heteropoly-acids and their salts have been further investig-ated, particularly by J.F. Keggin,,' by X-ray powder methods.,*In combination, they behave as very large spherical ions, in theinterstices between which are found other ions and water molecules.It is interesting that the basicity of the different heteropoly-ionsis fixed by the number of positive ions that can fit in the invariablecalcium fluoride structure.Organo-metallic and Co-ordinate Ions.-The dimethylthalliumhalides are an isornorphous series of a layer lattice type. H. M.Powell and (Miss) D. Crowfoot 99 have shown that the H3C-T1-CH3group is linear, but also that the distance between neighbouringmethyl groups in neighbouring layers is 4.16 d., exactly the distancefound in methane but greater than that in durene, 3-81 A.Trimethylplatinum chloride is found by E.G. Cox and K. C.Webster to crystallise in the cubic system and to have a trigonalaxis of symmetry. The four platinum valencies for this type ofbinding cannot be coplanar. Diamminosilver groups inare probably linear, and the Cd(NH,), groups in CC~(NH,),(R~O,)~are tetrahedral.A large number of workers have been concerned t o show by X-raymethods whether the4-co-ordination compounds of nickel, palladium,platinum, and copper are tetrahedral or planar ; except the trimethylcompound, all are found to be planar. The clearest structure is thatof [Pd(NH,)4]C1,,H20, studied by B. N. Dickinson.6 The Pd(NH,),groups lie in planes 4.3 A. apart, which are separated by chlorine ionswith the water groups in the interstices of the structure.The Pd-Ndistance is found to be 2.02 A. and the group is strictly tetragonal.An elaborate study has been made of (NH4),CuC1,,2H,0 by 1,.Chrobak to clear up disputes that had existed as to its nature.s6 J. L. Hoard and L. Goldstein, J. Chem. Physics, 1935, 3, 117.9 7 Proc. Roy. SOC., 1934, [A], 144, 75; A., 1934, 479; see also J. D. H.Donnay and J. MBlon, Proc. Nat. Acad. Sci., 1934, 20, 327; A., 1934, 947;J. W. Illingworth and J. F. Keggin, J., 1935, 575; A., 834; J. A. Santos,Proc. Bog. SOC., 1936, [A], 150, 309; 0. Kraus, 2. Krist., 1935, 91, 402.ss See Ann. Raports, 1933, 30,409.1 Ibid., 1935, 90, 561.2. Krist., 1934, 8'9, 370; A., 1934, 479.R. B. Corey and R. W. G. Wyckoff, ibid., 1934,87,264; A., 1934, 352.R.B. Corey and K. Petrescov, &id., 1935, 89, 528.K. S. Piker, ibid., 92, 131.5 Ibid., 1934, $8, 281; A., 1934, 1161. Ibid., p. 36; A , , 1934, 1060BERNAL AND WELLS : CRYSTAL CHEMISTRY. 221A planar arrangement is found for the four chlorine atoms, thoughthey turn out to be at different distcznces-2.0 and 2.35 A.-from thecopper atom. The water molecules here are, however, co-ordinatedat a distance of 2-0 A. from the copper. E. G. Cox, W. Wardlaw, andK. C. Webster 7 have studied a number of other complex derivativesof palladium, platinum, nickel and copper. The most convincingevidence is obtained from the dithio-oxalate derivatives of thefirst three metals, which crystallise with the whole of the complexin planes separated by a distance of 5.5 A.apart and havediad axes of symmetry. Similar evidence is provided by salicyl-aldoxime and other complexes of these metals, all of which crystallisewith the complex molecules in layers 4 A. apart, excluding anypossibility of tetrahedral arrangement.Similar results have been found for palladium chloride, oxalate,and chloro-dinitrite,8 but is was impossible to analyse the simplecompound PdC12(NHJ2 on account of its forming a two-dimensionallattice of a statistical kind (see p. 188).A study showing a complete isomorphism between the tetra-cyanide salts of nickel, palladium, and platinum and one less com-plete between those of Mg, V and Er has been made by H. Brasseurand his collaborator^.^ The complex has a centre of symmetry andtherefore must have a planar configuration. On the other hand, inCs3CoC1, studied by H.M. Powell and A, F. Wells lo the complexCoCl, seems to exist as a regular tetrahedron, the remaining C1ion occupying a different place in the structure.Of the hexa-co-ordinated compounds an interesting example isgiven by [Rh(NH3)5C1]C12.11 The complex ions are slightly distortedoctahedra, held together by the free chlorine ions. Nickel nitrites l2and caesium aurichlorides l3 have also been studied.Hydrated 8uZts.Recent detailed studies of hydrated salts havebrought out the function of water of crystallisation much moreclearly. Water is found, in general, either attached to a positive7 J., 1935,731,1475; see also F. W. Pinlcard, E. Sharratt, W. Wardlaw, and(in part) E.G. Cox, J., 1934,1012; A., 1934,994; E. 0;. Cox, H. Saenger, andW. Wardlaw, ibid., p. 182; A., 1934, 397.F. G. Mann, (Miss) D. M. Crowfoot, D. C. Gattiker, and (Mrs.) N. Wooster,J., 1935, 1642.a J. Pi6rard and A. de Rassenfosse, 2. Krist., 1935, 90, 470; A. de Rassen-fosse and J. PiBrard, Bull. SOC. Sci. LiBge, 1935, 74; H. Brasseur and A. deRassenfosse, ibid., pp. 24, 68,171, 277 ; H. Brasseur, A. de Rassenfosse, and J.Pidrard, Compt. rend., 1934,198, 1048; A., 1934, 479.10 J., 1935, 359.11 C. D. West, Z. Krist., 1935, 91, 181.12 A. Ferrari and C. Colla, Qazzetta, 1935, 65, 168, 789, 809; A. Ferrari, A.13 N. Elliott, J . Chem. Physics, 1934, 2, 419 ; A., 1934, 947.Baroni, and C. Colla, ibid., p. 797222 CRYSTALLOGRAPHY.ion, or lying between other water molecules and negative ions.Ineither case the arrangement of the water molecule is such as to satisfythe binding properties postulated by the Bernal-Fowler theory.14In the first case the ion may occupy one or two of the positions ofnegative attraction in the molecule ion, according to its polarisingpower. The degree of binding of the water is shown very clearly byits infra-red absorption,l5 which varies from that of ice to that ofwater according to the tightness with which the molecule is held.Lithium sulphide monohydrate is the only example of a monohydr-ate studied.l6 Each water molecule is attached to one lithium atom,to two sulphate oxygens, and to another water molecule. Thebinding is so slight, M,O-H,O = 2.86 A., that rotation of groups isnot excluded. The crystal structure of CuS04,SH,0, which has beencompletely worked out by C.A. Beevers and H. Lipson,17 is ofparticular interest to chemists. The five water molecules are differ-ently situated ; four are arranged in a plane about the copper atomsat a distance of 1.97-2-0 &, and the other is not attached to anymetal atom but connected tetrahedrally to two water molecules ofthe first type and two sulphate oxygens. The copper group alsocontains two sulphate oxygens, but at a greater distance, 2.3,2-45 8., so there is no doubt that water molecules are here held byplanar co-ordination forces. The whole structure satisfies veryexactly Pauling's ionic valency scheme. C. A. Beevers and C. M.Schwartz l8 have examined NiS04,7H,0, and here again six of thewater molecules are co-ordinated to the nickel and one is loose.In the hexahydrates of magnesium and aluminium halides, analmost regular octahedral co-ordination of water molecules roundthe cations is found.lg Some curious isomorphous relations havebeen found by C.D. West 2o in the hydrates of perchlorates andiodides. In the first place, iodine and perchlorate ions seem tofunction almost identically in the structure owing to high symmetry,not to rotation. In the second place, Ba(C10,),,3H20 is foundto be isomorphous with LiC104,3H,0.A very complete study of the alums M1I16H2O,MI( S04),GH,0 hasbeen made by H. Lipson.21 Three types of alum structure have beenl4 See Ann. Reports, 1934, 31, 42.15 L.Passerini, Gazzetta, 1935, 65, 502, 511 ; A., 1300.16 G. E. Ziegler, 2. Krist., 1934, 89, 456.1' Nature, 1934,133,214; A., 1934,243 ; Proc. Roy. SOC., 1934, [A], 146,570.la 2. Krist., 1935, 91, 157.K. R. Andreas and J. Gundermann, ibid., 1934, 87, 345; A., 1934, 479;K. R. Andress and C. Carpenter, ibid., p. 446 ; A., 1934,947.20 Ibid., 88, 198; A., 1934, 1161; ibid., 1935, 91, 480.21 Phil. Mag., 1935,19,887; PTOC. Roy. SOC., 1935, [A], 151,347; A., 1308;H. Lipson and C. A. Beevers, ibid., 148, 664CROWFOOT : MOLECULAR CRYSTfiS. 223found, corresponding to (i) verylarge univalent ions, e.g.,Cs,N(CH,), ;(ii) medium-sized ions, Rb,K; and (iii) small ions, Na. All alumshave in common the co-ordination of six water molecules round thetervalent cation.The first two differ in the arrangement of theremaining six water molecules, and sodium alum has the reverseposition of the sulphate group along the trigonal axis. As all threeare cubic structures, we have here a case where only X-rays canshow that the series is not isomorphous.The only complete study of a salt containing molecules, otherthan water and ammonia, has been made by S. B. Hendricks forCaS04,4CO(NH2)2.22 The urea groups act as dipole links betweenthe positive and negative ions of the salt. AgN03,CO(NH2), hasprobably a similar structure.23 J. D. B.A. F. W.MOLECULAR CRYSTALS.Last year some of the most important advances described in thereport were those resulting from the application of rapid preliminarymeasurements and extensive surveys of related substances to thestructure of unknown chemical compounds.Such was the workon the sterols, sex hormones, and related compounds which hascontinued to yield valuable results. This method depends upon theuse of optical or magnetic measurements to determine the probableorientation of the molecules in the crystal, and upon the use ofmolecular models derived from the results of exact structure deter-minations.Considerable doubt has been expressed in the past as to theabsolute reliability of the first of ilhese methods, and it is thereforeparticularly satisfactory that we now have several examples in whichexact structure determinations have confirmed the molecular orient-ations chosen from optical and magnetic data.2 Further, a verycomplete test has been applied to the whole theory by S.B. Hen-dricks and W. E. Derning3 from an examination of the opticalanisotropy of the crystals of a series of oxalates. They have22 J . Physical Chem., 1933, 37, 1109; A., 1934, 243.23 G. L. Clark and C. 0. Werner, 2. Krist., 1934, $8, 162; A., 1934, 1162.1 G. E. R. Schulze, 2. physikal. Chem., 1934, [A], 171, 436; Y. Go and 0.Kratky, ibid., [B], 26,439 ; J. D. Bernal and (Miss) D. M. Crowfoot, Chem. andId., 1934,53,953; A., 1934, 1354; 1935,54,701; A., 1120; D. M. Crowfoot,ibid., p. 568; A. Kofler and A. Hauschild, 2. physiol. Chem., 1934, 224, 150;A., 1934, 815; S . B. Hendricks, 2. Krist., 1934, $9, 427; A,, 1935, 152; A.Neuhaus, ibid., 89, 505; A., 1934, 413; ibid., 1935, 9Q, 415; A., 1195; H.Brasseur, ibid., 91, 369; G.Mackinney, J . Arner. Chem. SOC., 1934, 58, 488;A., 1934, 352.2 K. S. Krishnan and S. Banerjee, Proc. Roy. Soc., 1935, 234,265.3 2. Krist., 1935, 91, 290224 CRYSTALLOGRAPHY.calculated the birefringences of the crystals from the molecularrefractivities and the orientations of the molecules in the crystalpreviously deduced from X-ray data. There is very close agreementbetween the calculated and observed birefringences, which indicatesthat no confusion is caused by intermolecular interaction. Similarcalculations have been made with good results for guanidiniumiodide and for sodium carbonate rnon~hydrate.~ The usefulnessof even the molecular refractivities calculated direct from the crystalrefractive indices as an indication of molecular structure has beendemonstrated by A.Neuhaus for a large series of compounds.Still more important advances have been made in the directionof exact structure determination, and it is in this field that we havemost interesting results to report. Last year we listed the inter-atomic distances found in seven organic crystals of which completestructure analyses had been made up to that date, but this listcould now be more than doubled. A very good summary of theextent to which interatomic distances had been measured withprecision by X-rays up to the end of 1934 has been given by J. M.Robertson.' Another list also appears in a paper by H. Markwhich supplies in addition a valuable survey of the various physicalmethods available for the study of the shape and structure oforganic molecules.The first Fourier analyscs of organic compounds, such as those ofurea, thiourea, naphthalene, and anthracene, did little more thanrender precise the pictures of the structures already accepted byorganic chemists through the attachment of these exact interatomicdistances.But the last two years have seen the extension of themethod into the field of pure chemistry in two directions. Thefirst is the direct determination of the mutual orientation of theconstituent atoms where this is unknown, as in the case of cyanurictriazide (see below). The second is a determination of the nature ofthe chemical bonds present. The measurements of standardorganic compounds have provided us with a scale of bond lengths,normal distances between atoms both inter- and intra-molecular, tobe applied to actual substances under investigation. But the resultsobtained by the application of this scale are rapidly leading usbeyond the pictures of molecular structure given us by classicalorganic chemistry.Simple Molecular Structures ,-Considerable work has been doneby improved techniques in the examination of crystals at lowH.Brasseur, ibid., p. 282. 4 W. Theilacker, 2. Krist., 1935, 91, 90.6 Ber., 1934, 67, 1627.7 Phys. SOC. Rep., p. 46; Chem. Rev., 1935,16, 417.3 2. Elektrochem., 1934,40,413; A., 1934, 1088CROWFOOT : MOLECULAR CRYSTALS. 225temperatures. L. Vegard has determined the structures ofa-(fixed) and P-(rotating) nitrogen, and shown that those of carbonmonoxide are almost exactly similar.10 The C-0 distance in solidcarbon dioxide is found to be 1.13 -J= 0.02A.11 The structure ofoxygen in its different forms has been very much studied, but noconclusive results have been obtained.Absorption-spectrumstudies l2 point to the existence of O4 molecules in liquid oxygen andin all forms of solid oxygen. Vegard l3 has shown that y (high-temperature) oxygen has a cubic structure a = 6-83 A. containing16 atoms and consequently almost certainly four rotating moleculesof 0,. These must lie alongstructure such as (I) is more0(1.1 00 0have very similar structures,the trigonal axes, and consequently aprobable than (11); a- and p-oxygen(11.)0-00-0but they are rhombohedra1 and notcubic and contain three molecules of 0,.E.F. Burton and W. F. Oliver l4 have shown that water vapourFIG. 5.Molecule of Sulphur S,.condensed a t temperatures below -- 110" gives rise, not to ice, butto water glass, which, to judge from the position of the intensitymaxima, must have a density equal to or less than that of ice a t thesame temperature. At - 110" this water glass rapidly devitrifies toordinary ice. Solid hydrogen peroxide l5 is found to have a tetra-gonal structure, c = 8-02, a = 4.02, with four molecules per cell.The arrangement may be similar to that of cristobalite.The structure of two forms of sulphur has been determined.A careful study of rhombic sulphur by A.E. Warren and J. T.Burwell l6 has shown that the cell contains 16 molecules of S8;these molecules are in the form of puckered octagons (see Fig. 5),9 Proc. K. Alcad. Wetensch. Amsterdam, 1934, 37, 780; A., 1935, 147.10 2. Physik, 1934, 88, 235; A., 1934, 587.11 W. H. Keesom and J. W. L. Kohler, Physicu, 1934, 1, 167; A., 1934, 244.12 A. Prichotko, M. Ruhemann, and A. Federitenko, Physikul. 2. Sovietuniora,1935, 7, 410; A., 1291; M. Guillien, Compt. rend., 1934, 198, 1456; A., 1934,581 ; H. Salow, 2. Physik, 1934,90,11; A., 1934,1055; W. Finkelnburg, ibid.,p. 1 ; A., 1934, 1055.13 Ibid., 1935, 98, 1.15 F. Feher and F. Klotzer, 2. Elektrochem., 1935, 41, 850.1 6 J . Chem. Physics, 1935, 3, 6.l4 Proc. Roy. SOC., 1935, [ A ] , 153, 166.REP.-VOL.XXXII. 226 CRYSTALLOGRAPHY.with an S-S distance of 2.12 A. (calc., 2.16) and a bond angle of105.4". The S8 molecules are stacked in four layers approximatelyperpendicular alternately to the (110) and (1x0) directions in thecell ; the nearest approach between sulphur atoms in neighbouringmolecules is 3.3 A. Plastic sulphur is the simplest type of poly-merised fibre structure. On stretching, it can, like rubber, bemade to crystallise, though normally it is amorphous: that is,the sulphur chains are tangled with each other. The structurethat these fibres form has been thoroughly worked out by K. H.Meyer and Y. Go;17 the cell is monoclinic with an identity periodof 9.26 8. along the fibre axis. A close analogy to the polymorphismof sulphur is furnished by (PCl,N), which forms both 3- and 6-unitrings18 and also elastic polymerised fibres of period 5.16 Partialstudies have been made of two red monoclinic varieties of selenium 2owhich also probably contain Se8 molecules.The structure of red and black phosphorus has been studied byR.Hultgren, N. S. Gingrich, and B. E. Warren.21 The amorphousform of both has been analysed and shows a layer lattice of 3-co-ordination type not unlike that of graphite with an internucleardistance of 2.28B. The crystalline form, on the other hand, is anew type of structure and, like arsenic, of the layer type, with3-co-ordination but with a rhombic type of trigonal layers. Theatoms in the layers are 2.188. apart (calc., 2.20A.). The atomsin different layers are separated by 3.68 A.Molecules of the symmetrical types AB,, AB,, generally formsimple crystal structures.Exceptions to this rule are ZrF4 andHfF, which give monoclinic crystals.22 Pentaerythritol tetra-phenyl ether, on the other hand, has a simple tetragonal cell witha = 12.32, c = 8-43 A., with alternating tetragonal symmetry andtwo molecules in the unit cell.23 This is very similar to tetraphenyl-methaneY2, which is also tetragonal, a = 10.86, c = 7.26 B.,differing only in the smaller axes and in the fact that here the mole-cule also possesses planes of symmetry. Hexamethylethane andhexachloroethane,25 above - 125" and 71" respectively, are cubic17 Helv. Chim. Acta, 1934, 1'7, 1081.l8 I?. Renaud, Ann. Chirn., 1935, [xi], 3, 443; A., 833; Cornpt.rend., 1934,19 Arch. Sci. phys. nat., 1935,17, supp. 139; Trans. Paraday SOC., 1936, 32,30 H. P. Klug, 2. Krist., 1934, 88, 128; A,, 1934, 1160.21 J . Chem. Physics, 1935, 3, 351.22 G. E. Schulze, 2. Krist., 1934, 89, 477.23 J. Beintema, P. Terpstm, and W. J. van Weerden, Rec. trav. chim., 1935,e4 W. H. George, Proc. Roy. Soc., 1926, [A], 113, 585.25 C. D. West, 2. Krist., 1934, 88, 195; A., 1934, 1162.198,1159; A., 1934, 615.148.44,627 ; A., 1195CROWFOOT : MOLECULAR CRYSTALS. 227body-centred structures, again with only two molecules in the cell,due presumably to molecular rotation. Of the less symmetricaldisubstituted ethane derivatives, s-di-iodoethane 26 shows a consider-ably more complicated packing. The molecules do not rotate aboutthe C-C bond a t ordinary temperatures, and it is interesting that theposition taken up by the iodine atoms with respect to one anotheris the same as that in s-di-iodoethylene, vix., the trans-position.The crystals of these two compounds are very closely isomorphous.Aliphatic Compounds.-Among the main group of aliphatic com-pounds exact structure determinations are still very rare.We havestill no Fourier analysis of aliphatic long chains, though a beginninghas been made by D. A. Wilson and E. Ott 27 towards the calculationof the intensities of the main plane reflexions of a series of aliphaticalcohols. Otherwise, work in this field is mainly confined in useful-ness to the identification of products from natural sources 28together with preliminary studies on the structure of dibasic acids,29trigly~erides,~O and dihydrazides .31 I n the series of the poly-methylene ring compounds 32 the interesting fact emerges that,whereas a t ordinary temperatures and in the liquid the molecularvolume of a methylene group is greater in the cyclic than in thestraight-chain compounds, yet this difference disappears a t lowtemperatures.The only complete structure determinations in the aliphaticseries are those of hexamethylenetetramine and urea, which havebeen further refined by R.W. G. Wyckoff and R. B. C ~ r e y . ~ ~ Theirresults give valuable new readings for the P curves of carbon andnitrogen in this type of compound, and also lead to slightly differentvalues for the interatomic distances.In hexamethylenetetramine,CH,-N = 1.42 A., while in urea, C-=O = 1.25 and C-NH, = 1-37 A.The shortening of the distance of C-N in urea from 1-42 to 1.37 8.is of particular interest, since here resonance may occur betweenthe two forms H2N>Cx0 and HN>C-OH, the former pre-dominating.H2N H P26 H.P. Klug, J . Chem. Physics, 1935,3,747; 2. Krist., 1935,90,495; A., 1195.2 7 J. Chem. Physics, 1934, 2, 231, 239; A., 1934, 720.28 F. J. E. Collins, J . SOC. Chem. Inti., 1935, 54, 33; S. H. Piper, A. C.Chibnall, and E. F. Williams, Biochem. J., 1934, 28, 2175; A. C. Chibnall,S. H. Piper, A. Pollard, E. F. Williams, rtnd P. N. Sahai, ibid., p. 2189; A. C.Chibnall and S . H. Piper, ibid., p. 2209; A., 1935, 551, 152, 267, 204.29 F.D. La, Tour and A. Riedberger, Compt. rend., 1934, 199, 215; A.,1934, 1060; F. D. La Tour, ibid., 1935,201,479; A., 1351.30 C. E. Clarkson and T. Malkin, J., 1934, 666; A., 1934, 720.31 M. Wolf, Physica, 1934, 1, 417; A., 1934, 587.32 A. Miiller, Nature, 1935, 135, 994 ; A ., 957.33 Z. Krist., 1934,89, 462; cf. R. Reinicke, ibid., 1935, 87,417228 CRYSTALLOGRAPHY.In the guanidinium halides investigated by W. TheilackerF4the distance C-N is still more reduced, the value given being 1-18 a.,although the measurement is not susceptible of great accuracy.Theilacker has studied the chloride, bromide, and iodide, but onlyfor the last could the crystal structure be determined with anyapproach to precision. This forms a typical layer lattice withiodine ions arranged on a network of puckered hexagonal ringsseparated by guanidine ions.The guanidinium ion C(NH2),shows trigonal symmetry, all three nitrogen atoms being crystal-lographically equivalent, and the ionic character cannot thereforeFIG. 6. FIG. 7.Carbon. 0 Oxygen.The. oxalate-ion.4 O Nitrogen.The molecule Be40(CH,*COO) (one acetate groupbe associated with any particular nitrogen atom of the complex.The structure may be written as (I) with a positive charge on thei s omitted).NH2carbon, or as due to resonance between three double- bondedstructures of the type (11).Considerable interest has centred round another " resonance "problem, wuiz., the structure of the carboxyl group, and severalstudies have been made of carboxylic acids and their salts.35 Besidess4 2.Krist., 1935, 90, 51, 256; cf. A. Swaryczewski, Bull. Acad. polonaise,1933, [A], 359; A., 1934, 587; ibid., 1934, [A], 246; A., 1935, 152.35 L. P. Biefield and P. M. Harris, J . Amer. Chem. SOC., 1935, 57, 396; E.Hertel and G. X I . Romer, 2. physilcal. Chem., 1934, CB], 27 282; A., 1935, 152;R. C. Evans, 2. Krist., 1935, 92, 154CROWFOOT : MOLECULAR CRYSTALS. 229the electron diffraction of formic alcid 36 reported last year, Paulinghas examined the crystal structure of basic beryllium acetate.37Here he finds actual molecules Be,O(CEI,*COO), present in thecrystal and packed together as are the atoms in diamond. Insidethe molecules (Fig. 6) each beryllium atom is a t the centre of atetrahedron formed by three oxygen atoms contributed by acetategroups and the central basic oxygen.The interatomic distanceshave not been determined with any great accuracy, but Pauling candetect, as in formic acid, no difference between the two oxygen atomsof the carboxyl group. He gives the C-0 distance as 1.29 0-058. and the 0-C-0 angle as 124" & 3".A somewhat more exact determination of the configuration ofthe carboxyl group has been made by W. H. Zachariasen38 in hisanalysis of the structure of oxalic acid dihydrate, and this has beenconfirmed by S. B. Hendricks for other o x a l a t e ~ . ~ ~ Zachariasenfinds for the oxalate group a planar configuration with a centre ofsymmetry (Fig. 7). The C-C distance is 1-59 & 0.07&, C-0 inboth cases 1-25 0.05 A., and the 0--GO angle 126".The two oxygenatoms are not, however, structurally identical, and their arrangementwith respect to the water molecules in the crystal is different.Since the distances between the oxygen atoms in the oxalate groupsand water molecules are only 2.87, 2-77, and 2-60 8., considerablyshorter than the usual intramolecular distance of 3.5 k, Zachariasenhas suggested that the water molecules bind the oxalate groups inchains by a series of hydrogen bonds. Later, J. D. Bernal and(Miss) H, D. Megaw 40 showed that there are two possible ways ofachieving this binding through two different systems of combinedhydrogen and hydroxyl bonds according to whether 0, or 0, isacting as hydroxyl group.The interconversion of the two systems iseffected by the movement of hydrogen atoms along the oxygenchains, and this movement provides a mechanism for the resonanceof the two forms :It does seem, however, that resonance may not be complete, and thelimits of error of Zachariasen's measurement leave still open thepossibility of comparatively small differences in the C-0, andC - 0 , distances.Aromatic Cmpounds.-In the aromatic series a number of new3G L. Pauling and L. 0. Brockway, Proc. Nat. Acad. Sci., 1934,20, 336.37 L. Pauling and J. Sherman, ibid., p. 340.38 2. Krist., 1934, 89, 442; A., 1935, 152; Physical Rev., 1934, 45, 755.39 2. Krist., 1935, 91, 48.4 O PTOC. ROY. A'Yoc., 1935, [ A ] , 151, 384230 CRY STALLOQRAPHP.and very important structure analyses have been carried out.Thesimplest of these is resorcin01,~~ of which only a preliminary reportis available. Here the benzene ring appears regular, with a C-Cdistance 1.41 A,, and C-OH 1-35 A. The molecules are arrangedin spiral formation about the diad screw axis in such a way thathydroxyl groups in neighbouring molecules are brought to within adistance of 2.66-2.76A. of one another. This close approachindicates binding between the hydroxyl groups of the kind discussedabove with reference to oxalic acid and also among inorganic com-pounds. Such association between hydroxyl groups has long beenrecognised in organic chemistry, but these measurements providethe first accurate description of the nature of the binding.Research has been continued on several compounds based oncondensed ring systems.The complete analysis of chrysene42 isof particular interest as a control to the work undertaken on hydro-carbons related to the sterols.43 Preliminary measurements areF I ~ . 8.Dibenzyl.also reported for 1 : 2-cyclopentenophenanthrene 44 and for dodeca-hydrobenzanthracene 45 which shows, as would be expected, aconsiderable thickening of the molecule, and also of the optical andmagnetic properties of 1 : 2 : 5 : 6-dibenzanthracenej6 1 : 3 : 5-Triphenylbenzene 47 is closely related in crystallographic behaviourto the condensed-ring compounds, since the molecules appearperfectly flat with all the phenyl rings extended symmetricallycoplanar with the central ring.In the crystals, they are packedclosely interlocking in layers, with the molecular planes very slightlyinclined to the normal to a pseudotrigonal axis.4 1 J. M. Robertson, 2. Krist., 1934, 89, 318; Nature, 1935,136, 755.4 2 J. Iball, Proc. Roy. SOC., 1934, [A], 146, 140; A,, 1934, 1162.4 3 J. D. Bernal and (Miss) D. M. Crowfoot, J . , 1935, 93.44 J. Iball, 2. Krist., 1935, 92, 293.4 5 Idem, Chem. and I d . , 1935,54, 716.4 G J. Iball and J. M. Robertson, Nature, 1933,132,750; A., 1934, 17; J. D.13erna1, ibid., p. 751; A., 1934, 18; K. S. Krishnan and S. Banerjee, 2. Krist.,1935, 91, 170, 173.4 7 B. P. Orelkin, J . Ben. Chem. Russia, 1933,3, 643; A., 1934, 134; (Mrs.)K. Lonsdale, Nature, 1934, 133, 67; A., 1934, 134; B. Orelkin and (Mrs.) K.Lonsdale, Proc.Roy. Soc., 1934, [ A ] , 144,630; A., 1934, 834; K. S . Krishnanand S. Banerjee, Nature, 1934,133, 497 ; A., 1934, 479CROWFOOT : MOLECULAR CRYSTALS. 231In dibenzyl, on the other hand, in contrast with the arrangementin triphenylbenzene and also in diphenyl, the two benzene rings areno longer coplanar. Preliminary examination by J. Dhar 48suggested a molecule only slightly distorted from the coplanarstructure, but the complete analysis by J. M. Robertson49 showsclearly that the planes of the benzene rings are directly at right anglest o the zigzag of the CH, groups (Fig. 8). Between the aliphaticand aromatic carbon atoms the distance is 1.47 A., and between thetwo CH, groups it is 1.58 A. The angle between the bonds of theCH, groups is 109*2-112".In all the compounds so far considered, the benzene rings appearas perfectly regular hexagons with a distance between the carbonatoms of 1.41 A.In benzoquinone, chemical theory would expectconsiderable distortion from this model, and this has been found tobe the ~ase.~O Owing to the orientation of the molecules in thecrystal, their dimensions cannot be obtained from the FourierFIU. 9.Benzoqu!inone.analysis with such accuracy as in other examples. But there doesappear to be definite lengthening of the C-C bonds adjacent to the(2x0 group to 1.50b., and shortening of the ring bonds parallelto this to 1-32b., corresponding to the appearance of aliphaticsingle and double bonds (Fig. 9). The C=O distance appearssmaller than might be expected, 1*14A., but this agrees with theC=O distance of 1.16 A.found in carbon dioxide from the infra-redabsorption spectrum and 1.13 A. from crystal-structure data atlow temperatures (p. 225). It may be compared with the C=Qdistance of 1-25 A. found for urea and oxalic acid, and in so far, itconfirms that the latter are midway between ' true ' single anddouble bonds.This distortion of the benzoquinone molecule is, a t least in itsdirection, in accordance with current chemical theory. But nearlyas far-reaching changes of an altogether unexpected kind have48 Current Sci., 1934, 2, 480; A., 1934, 948.4 9 Proc. Roy. SOC., 1934, 146, 473; 1935, 150, 348.60 Ibid., p. 106; Nature, 1934,134, 138; A., 1934, 948232 CRYSTALLOGRAPHY.been found by R.W. James, G. King, and H. Horrocks in p-dinitro-ben~ene.~l A preliminary examination of this compound, carriedout by I<. Banerjee,52 gave results roughly in agreement with thestereochemical picture presented by the ordinary chemical formula.The exact structure obtained by James by Fourier projections onthree planes reveals important departures from this picture whichare best shown by reference to Fig. 10. The molecule as a wholepossesses a centre of symmetry. The nitro-group is nearly planar,but apparently not quite, and nearly coplanar with the benzenering, one oxygen atom being in this plane and the second slightlylifted above it. The distance between the carbon atom of thering and the nitrogen atom is 1-53,&., decidedly longer than theC-N distance of hexamethylenetetramine.Further, the two oxygenatoms are at different distances from the nitrogen, vix., 1-10 andFIG. 10.p -Dindrobenzene.1.25A.N+O in the usually written structure of the nitro-group -Nfthough both are actually shorter than the accepted distances,uuix., for N=O, 1.22 A., and for N+O, 1.36 It is surprising,however, that any difference should exist between them at all,since the resonance energy between the two equivalent configurationsis considerable. Very careful measurements by H. 0. Jenkins 54have shown that p-dinitrobenzene has no dipole moment, and thishas been taken to prove that the oxygen atoms of the nitro-group areequivalent. The only alternative is to assume that the exact con-figuration shown to exist in the solid state, which has a centre ofThese might correspond to distances between N=O and\O?51 Proc.Roy. SOC., 1935, 153, 225.62 Phil. Mag., 1934, 18, 1004.53 N. V. Sidgwick, Ann. Reports, 1934,31, 39.54 Nature, 1934, 134, 217CROWFOOT : MOL'ECULAR CRYSTALS. 233symmetry, is also that present in solution, i.e., that there is no freerotation about the C-N bond.Perhaps one fact in support of this hypothesis is the very markedinteraction that appears to occur between the nitro-group and thebenzene nucleus. The substitution of the nitro-group has produceda considerable shortening of one of the bonds in the ring adjacentto it-that approximately parallel to the shorter N=O bond-though there is no compensatory lengthening of other nuclear bonds.The configuration of the ring as a whole can be regarded as tendingtowards one of the Dewar types of canonical structure which inFIG.11.Cyanuric triazide.benzene itself is probably only present to the extent of about 703%(Pauling and Wheland).55 But we have evidently t o deal here witha process which it is practically impossible to discuss in terms ofordinary valency changes. It would be most interesting if thisstriking modification in shape of the benzene nucleus produced bythe substitution in it of nitro-groups could be related to the generalphenomenon of the influence of substituents on the reactivity of thebenzene nucleus.More information in the same direction is given by the determin-ation of the crystal structure of cyanuric triazide, one of the most im-portant and elegant pieces of work accomplished in the last two years.B G J.Chem. Physics, 3933, 1, 362.H 234 CRYSTALLOGRAPHY.Two parallel investigations have been undertaken. That of E. A.Hughes 56 leads to a structure agreeing within the limits of his ownexperimental accuracy with that of (Miss) I. KnaggsY57 although itmakes no pretensions to such perfection. It is, however, of someinterest in indicating how far merely visual estimates of intensitiesmay be relied on to give a very good first approximation picture ofa complex structure. Miss Knaggs has made very accurate intensitymeasurements and converted these into an absolute scale bycomparison with standard crystals both by ionisation and photo-graphic methods. The results of her analysis lead to the structureof the cyanuric triazide molecule shown in Fig.11. The moleciileas a whole is planar, with a trigonal axis perpendicular to the plane.The azide group is attached to the carbon atom of the ring and isproved to be linear, the possible deviation from the straight line beingnot more than 4". It is, however, not centrosymmetrical, thedistance between the nitrogen attached to the ring and the centralnitrogen atom being 1*26A., while that between the two outernitrogen atoms is 1.11 A. This is in good agreement with thesuggestion of N. V. Sidgwick 58 that the actual structure is the resultof resonance between -N=NTIU and -N+-N?N.The ring itself is considerably distorted from the hexagonalshape.It consists of alternate carbon and nitrogen atoms whosedistances are alternately 1.31 and 1.39 8. apart. Both thesedistances are shorter than C-N of hexamethylenetetramine, but asa first approximation they may be attributed to alternate doubleand single links. We must assume that, in contrast to benzeneitself, one of the two Kekulk forms is frozen in cyanuric triazide bythe unsymmetrical form of the azide substituent, just as in p-dinitro-benzene another of the canonical structures appears forced on themolecule.A number of other investigations of aromatic compounds arestill in a preliminary stage.59 That of W. -a. Taylor on methylene-blue halides 6o is interesting in showing that the packing of organicions in a crystal follows much the same principles as that of inorganic66 J .Chem. Physics, 1935, 3, 1, 650.5 7 Proc. Roy. SOC., 1935, [A], 150, 576; A., 1194; Nature, 1935, 135, 268;6 8 Trans. Paraday SOC., 1934, 30, 801.59 R. G. Wood, 8. H. Ayliffe, and N. M. Cullinane, Phil. Mag., 1935, [vii],19, 405; E. Hertel and E. Dumont, 2. physikul. Chem., 1935, [B], 29, 112;E. Hertel, ibid., p. 117; F. Wurstlin, 2. Krist., 1934, 88, 185; A., 1934, 1162;B. Gossner and H. Neff, ibid., 89,417; A., 1935, 152; J. Dhar and A. C. Guha,ibid., 1935, 91, 123; M. Prasad and P. H. Dalal, Current Sci., 1934, 3, 200;A . , 1935, 152; K. Banerjee and B. C. Guha, I n d i a n J . Physics, 1934, 9, 287.cf. (Sir) W. H. Bragg, ibid., 1934,134, 138; A., 1934, 948.Chew, and Id,, 1935, 54,732 ; 8.Kriat,, 1935,91,450 A,, 1295CROWFOOT : MOLECULAR CRYSTALS. 235ions. The iodide ion in methylene-blue iodide, for example, doesnot appear to be associated particularly with any special part ofthe C-N-S chain but is packed conveniently between the ends ofthe lath-shaped molecules. A still more complicated moleculartype is that of the phthalocyanines, where investigation proves thepresence of approximately square flat molecules having a centre ofsymmetry.6l This centre may be either left empty or occupied bythe metals nickel, copper, or platinum without distortion of thecrystal lattice, and in all these cases the four valencies of the metalsmust be coplanar.Carbohydrates.-The structure of the sugars is one of the mostdifficult problems to be attacked by the methods of X-ray crystal-lography. The shapes of the molecules depart very far from thesimple plane and linear varieties which have been dealt with alreadywith such success, and little or no help can be got from opticaldata to assist any intensive simple crystal analysis.X-Ray dataof a preliminary character have, however, continued to accumulate,both of simple mono-, di-, and tri-saccharides and their methyl,ncetyl, and other derivatives,62 and E. G. Cox, T. H. Goodwin, and(Miss) A. I. Wagstaff 63 have recently undertaken the review of theresults obtained from some sixty substances. The hardness,high melting point, and high densities of the crystals suggest thatthe crystal structure of the sugars is largely determined by thehydroxyl groups, which tend to interact to the greatest possibleextent and link the molecules together in all directions in the lattice.Any alteration in the groups attached to the ring, therefore, usuallyrequires a complete readjustment of the relative positions of thehydroxyl groups and hence of the molecules themselves.Thereis consequently very little relation a t first sight between the dimen-sions of unit cells of different compounds obtained by X-ray data.In the methylated sugars, however, the interactions betweenmolecules are greatly reduced, and here Cox has found it possibleto correlate directly the X-ray data with the shape and orientationof the molecule.The shape of the molecule must depend on the stereochemicalconfiguration of the pyranose ring on which it is based, and about61 J.M. Robertson, R. P. Linstead, and C. E. Dent, Nature, 1935,135,506 ;J. M. Robertson, J., 1935, 615.62 H. Braekken, C. J. Koren, and N. i\. Sorensen, 2. Krist., 1934, 88, 205;A., 1934, 1162; G. Vavrinecz, Magyar Chem. Fol., 1933,39,40; A., 1934, 18;G. L. LeuckrtndH. Mark, J . Amer. Chem. SOC., 1934,56,1959; A., 1934, 1162;I(. Hess and K. Dziengel, Ber., 1935, 68, [B], 1594; A., 1226; C. Trogus andK. Hess, ibid., p. 1605; A., 1308; S. B. Hendriclcs, Nature, 1934, 133, 178;A., 1934, 241.63 J . , 1935, 978, 1498; A., 1195236 CRYSTALLOGRAPHY.this there has been considerable doubt. The most probablealternatives appear to be those drawn in Fig.12, either one of theSachse forms (cis and trans) found in cyclohexane derivatives orthe flat ring, previously discussed by Cox with reference to a-methyl-glucoside. In this ' flat ' ring the carbon atoms are probably inone plane, the oxygen slightly lifted out of it. In the Sachse ringsit is possible for hydroxyl groups t o be so attached that they lieeither directly in the ring or approximately at right angles to it,and this should lead to markedly different values for the thicknessFIG. 12.IH P@Carbon. 0 Oxygen.Possible conjiguration of the pyranose ring.to be observed for the molecules in the two cases. In the ' flat'ring no such distinction exists.Cox finds that the crystal structure of the methylated sugarsprovides a means for distinguishing the two cases.These tendto form long needles with an identity period along the needle axisin many cases of only about 4*5A.-too short a distance t o referto anything but the molecular thickness. Cox has collected 26examples of sugars in which one unit cell dimension is of this orderof magnitude, since such measurements give unequivocally avalue for the maximum size of the thickness. His results show thatthere is very little difference between the thicknesses measuredfor sugars having different configurations of the methoxyl groupsCROWFOOT : MOLECULAR CRYSTALS. 237For example, the maximum ' thickness ' found for a-lactose,4.69&, is very little greater than that of the three P-methyl-glucosides, 4.41-4-45 A. , and that of hexamethyl lyxosido-lyxosideis even smaller, 4.20 8.This therefore suggests that the ringstructure present is of the ' flat ' variety.Cox also finds certain very interesting examples of morpho-tropic relations between the crystal forms of related substances.The unit cell dimension of p-methylarabinoside, a-methylfucoside,and a-methylgalactoside 6-bromohydrin are given in the table.H CH, CH,BrHo 1-0, H Hyd-:>;H IGH H,lOH I-o H I@= =>I H 1-1 OMe H '1-1 OMe H 1-1 OMeH OH H OH H OH,8 -Methylarabinoside. a-Methylfucoside. 6 -bromohy drin.a -Methylgalac tosidedl00 8-10 9-96 10.58b 7.74 7.87 7.81C 5-89 5-72 2 x 5.62These inter-relations bear out the correctness of the configurationsassigned on chemical and optical properties to these three compounds,and also incidentally indicate the presence of the pyranose ring inor -methylfucoside.An exact knowledge of the configuration of the pyranose ringshould prove an important aid towards the complete solution ofthe structure of cellulose, the problem of which has recently beenreopened by M.mat hie^.^^ There is now a considerable accumul-ation of data on the reactions of cellulose and various derivative^.^^X-Ray measurements have also been made on chitin by K. H.Meyer and G . W. Pankow,g6 who find an arrangement of chitobioseunits in the unit cell closely related to cellulose. Starch micelles64 Compt. rend., 1934, 198, 1434; A., 1934, 587; Chim. et Ind., 1934, 31,Spec. No. 792; A,, 1934, 760; see also W. A. Sisson, Textile Res., 1935, 5,119; A., 1308; G.Champetier, Bull. SOC. chim., 1934, [v], 1, 613; A., 1934,993; J. Barsha and H. Hibbert, Canadian J . Res., 1934, 10, 170; A., 1934,515.6 5 C. Trogus and K. Hess, Cellulosechem., 1934, 15, 1 ; A., 1934, 244; Ber.,1935, 68, 1986; K. Hess, C. Trogus, and G. Abel, Cellulosechem., 1935, 16,79; A., 1356; K. Hess, C. Trogus, W. Eveking, E. Garthe, and N. Ljubitsch,Annalen, 1933, 506, 260, 295 ; 507, 62 ; A., 1933, 1280; K. Hess and M. U1-mann, Ber., 1934,67, [B], 2131 ; A., 1935, 201 ; J. J. Trillat, J . Chim. physique,1934, 31, 125; A., 1934, 479; M. Mathieu, Compt. rend., 1934, 199, 55; A.,1934, 956 ; C. Trogus and I(. Hess, 2. Elaktrochem., 1934,40,193 ; T. Tomonari,ibid., p. 207; A,, 1934, 637; M. Wadano, K.Hess, and C. Trogus, 2. physikalChem., 1935, [B], 30, 159, 170, 183; J. J. Trillat, J . Phys. Radium, 1934, [vii],5, 207; A., 1934, 834.6 6 Helv. Chim. A d a , 1935, 18, 589; A., 753238 CRYSTALLOGRAPHYhave been shown to be surrounded by a layer of water which isactually crystalline 67 and an attempt has also been made t o followthe various changes that occur in micellar structure during bread-making.G8 Other interesting observations are those on the mole-cular structure of sisal, coir, and and on pine t r a ~ h e i d s . ~ ~The photographs of coir, for example, show two patterns of cellulosechains crossed at 45" to one another, and in pine tracheids a singlespiral of cellulose is formed.The Structure of the Proteins.-Since, on present chemical theory,the proteins are built of amino-acids united by peptide links, oneobvious method of approaching the problem of their structure is tostudy the simpler synthetic polypeptides.K. H. Meyer andY. Go 71 have now made X-ray measurements of di-, tri-, tetra-,penta-, hexa-, and hepta-glycylglycine, and also of a polyglycyl-glycine of molecular weight about 2000 obtained from glycocollcarbonate. Unfortunately, only powder photographs could beobtained, but these show decreasing crystallinity in passing alongthe series, the photograph of heptaglycylglycine being very similarto those of the polyglycylglycine. From the tetrapeptide onwardsthe strongest spacings seem to be at 4-15 A. and 3.15 A,, with theformer finally dominating.This suggests a relatively simplearrangement of the chains in layers 4.2 A. apart.These photographs do not bear any very marked resemblancet o those which have been obtained from natural fibres such asfibroin and keratin.72 But this could hardly be expected, since inthe natural fibres the hydrogen of glycine is substituted by a numberof different groups-the R groups of the general formula. Thisproduces an anisotropy in the directions perpendicular to thefibre axis, which should be shown in the method of packing thechains in the fibres. It is with this theoretical possibility thatAstbury associates the two spacings observed in a great number ofsclero-proteins of 4.65 A. and 10-11 8. The first, the backbonespacing, is very constant in a large number of proteins.Thesecond, the side-chain spacing, varies somewhat from one species67 N. H. Kolkmeijer and J. C. L. Favejee, 2. Krist., 1934,88, 226; A., 1934,6s J. R. Katz and A. Weidinger, Z. physikal. Chem., 1934, 169, 321, 339;69 E. N. Miles Thomas and J. Hewitt, Nature, 1935,136,69; W. T. Astbury,70 R. D. Preston, Phil. Trans., 1935, [B], 224,131.71 Helv. Clzim. Acta, 1934, 17, 1488; A., 1935, 152.72 W. T. Astbury, Kolloid-Z., 1934, 69, 340; A., 1935, 162; F. Halle, i b a . ,p. 324; A., 1935, 162; W. T. Astbury and H. J. Woods, Phil. Trans,, 1933,[A], 232,333 ; A., 1934,352.1162.17'1,181; A., 1934,1070; 1935, 165.It. D. Preston, and A. G. Norman, ibid., p. 391 ; J. Hewitt, ibid., p. 647CROWFOOT MOLEC!ULAR CRYSTALS. 239to another, as would be expected with the varying nature of theR groups.Photographs taken of the fibres in the usual way aboutthe fibre axis show both spacings on the equatorial layer, and it isnot possible to determine their mutual orientation. Astbury has,however, discovered that orientation of the keratin crystallitescan be effected by lateral pressure in the presence of steam or hotwater.73 The keratin molecule is first transformed from thea-(contracted) to the @-(expanded) form by the pressure, and thecrystallites then turn so as to bring the ‘ side-chain’ spacingnormal to the plane of flattening. The backbone spacing provesto be very accurately at right angles to this. The observationsprovide strong confirmation for Astbury’s picture of the @-keratinstructure as one of extended polypeptide chains, the most markedperiodicity along the chain being one of 3-4 A.All the interconversion phenomena found between a- and @-keratin, including the transformation by pressure described above,have now been observed also with myosin, the protein of muscle.74Thus, myosin forms fibres which, on being roughly stretched parallel,show an X-ray photograph resembling that of a-keratin.On furfherstretching, the @-keratin photograph appears, which may be ‘ set ’by exposure to steam, but the fibres, like those of keratin, areelastic and, provided the fibre has not been stretched and dried, willcontract again.and the a -+ @-transformation, in particular, has been observed infrog’s sartorius muscle and the retractor muscle of the foot ofMytelw ed~lis.75~So far the polypeptide theory of protein structure very adequatelyaccounts for the simpler X-ray diffraction effects obtained from thescleroprotein fibres and films.It is more difficult at first sight t orelate such a structure to the properties of the soluble proteins.These behave in the ultracentrifuge as if built up of large, approxim-ately spherical molecules of molecular weight 35,000 or somemultiple of this, and the presence of molecules of this order ofmagnitude has now been proved also by the X-ray diffraction effectsobtained from crystalline pepsin and insulin. The early attemptsto obtain diffraction effects for crystalline proteins failed to showmore than two diffuse amorphous rings at about 10 and 4.3 A.-73 W.T. Astbury and W. A. Sisson, Proc. Roy. Soc., 1935, [A], 150, 533;A., 1195.74 W. T. Astbury and S. Dickinson, Nature, 1935,135, 95; A., 376.7 5 E. Saupe, Kolloid-Z., 1934, 69, 357; A., 1935, 231; A. Kiintzel and F.Pralike, Biochem. Z., 1933, 267, 243 ; A., 1934, 316 ; F, Worschitz, Fortschr.R6ntgemtrahlen, 1934, 50, 174; A., 1935, 1003; (with J. von Herman), ibid.,p. 178; A., 1935, 1021; H. Kolpak, Naturwiss., 1934, 22,, 72; A., 1934, 244,Other studies have been made on actual76a W. T. Aathury and S. Dickinson, Nature, 1935,135, 765; A., 772240 CRYSTALLOURAPHY.Astbury's side-chain and back-bone spacings respectively. These,from their appearance, had to be attributed to an amorphous ratherthan to a truly crystalline structure.The detection of the latterwas made possible by J. D. Bernal's observation 76 that most proteincrystals readily lose water on exposure to the air, so that the crystalsits usually examined were only pseudomorphs. By taking photo-graphs of crystals of pepsin immersed in the mother-liquor, he wasable to obtain a true crystalline diffraction pattern, and thisprocedure has since been followed for a number of other proteins,e.y., haemoglobin, edestin, and e~celsin.'~ Imperfect powder photo-graphs of urease and pepsin had previously been obtained by I.Fanku~hen.7~ With insulin it has been found that the crystalsremain unchanged on drying, so that here no precautions arerequired to obtain crystalline diffraction effects.79Only in the case of pepsin and insulin are the data yet sufficientto give some information as to the size and shape of the units present,and these structures appear to be related to one another in a ratherinteresting way. In both cases, approximately spheroidal moleculesof molecular weight about 37,000 appear to be present, but thepacking is very different. In insulin the unit cell is rhombohedral,with a = 44.3, a = 115", and contains a single Svedberg unit ofweight 37,000. The size and shape of this molecule thereforefollow as equivalent to the size and shape of the unit cell, and thepacking together of the molecules is determined exactly by thelattice present. It is actually of a very close 8-co-ordination type.Pepsin, on the other hand, has a rhombohedral cell of dimensionsa = 162 8., a = 23"50', with a cell molecular weight 1,464,000.As this contains about 50% of water, only six Svedberg moleculesof molecular weight about 37,000 are present in the cell.It isimpossible in this case to say exactly how these molecules arearranged or what is their shape; but comparison of the cell dimen-sions and intensities of pepsin with insulin suggests strongly that thepepsin molecules are approximately spherical with radius 20 8. andarranged in a loose 4- co-ordination structure probably related tothat of p-carborundum. Such a structure leaves large channelsbetween the pepsin molecules to be filled with water or with themany impurities from which it is extremely difficult to free theprotein completely.So far this work gives us no information as to what is the actual76 Nature, 1934,133,794; A., 1934, 720; cf. W. T. Astbury and R. Lomax,7 ? R. W. G. Wyckoff and R. B. Corey, Science, 1935,81,365.7 8 J . Amer. Chern. Soc., 1934, 56, 2398.$o (Miss) D. M. Crowfoot, Nature, 1935, 135, 591.bid., p. 795 ; A . , 1934, 720CROWFOOT : MOLECULAR CRYSTALS. 241arrangement of the amino-acid residues inside these globular proteinmolecules, or what is their relation to the fibre proteins, but evidenceof the connexion between the two is coming from several directions.Amongst the fibre proteins, on the one hand, very long spacings havebeen observed for feather keratin by W. T. Astbury and T. C.Marwick,80 for tendon by Wyckoff, Corey, and J. Biscoe,81 and for anumber of materials such as collagen, gelatin, and nerves (thoughthese latter are more probably due to lipins) by G. L. Clark and hisco-workers.82 These long spacings point either to the presenceof large molecules or to the regular repetition a t large intervalsalong the chain of some particular pattern of amino-acid residues.Such a pattern might be produced by the breakdown of somespecial configuration of atoms on the denaturation of a solubleprotein. Astbury has accordingly studied this process in a numberof the plant globulins, and finds that denaturation does in all caseslead to considerable sharpening of the very diffuse rings observed at4.5 and 10A.83 Moreover, denatured fibres of edestin (fromcrystals of which Wyckoff has reported typical long spacings)have all the elastic properties of the fibre proteins and give a well-oriented fibre pattern showing the typical spacings 3.3 8. along thefibre axis and 10 and 4.5 8. across it.s4 Still more illuminatingresults have been obtained on single crystals of excelsin, a plantglobulin of molecular weight 200,000. By keeping this in water,Astbury was able to' obtain a single-crystal pattern showing verylarge spacings, but superimposed on this was a typical fibre patternwhich proved to be definitely oriented with respect to the crystalaxes. After the exposure, the crystal was no longer soluble, althoughin shape and appearance it remained unaltered. An insolublefibrous protein had evidently been obtained by some process ofdegeneration within the crystal. This suggests strongly that,whatever the configuration of the amino-acid residues is within themolecule, it is one that can be converted with very little changeof the mutual positions of the atoms into a fibre form. But whetherwe should imagine the soluble protein as built up of scleroproteinchains, or the scleroproteins as having some other structure relatedin an unknown way to a new and different configuration of residuesin the soluble proteins, remains still to be proved.Nature, 1932, 130, 309. 81 Science, 1935, 82, 175; A., 1266.82 G. L. Clark, E. A. Parker, J. A. Schaad, and W. J. Warren, J . Arner.Chem. Soc., 1935, 57, 1509; A., 1195; F. 0. Schmitt, G. L. Clark, and J. N.Mrgudich, Science, 1934, 80, 567; A., 1935, 231; F. 0. Schmitt, R. S. Bear,and G. L. Clark, ibid., 1935, 82,44; A., 1145.D. M. C.83 W. T. Astbury and R. Lomax, J., 1935, 846.84 W. T. Astbury, S. Dickinson, and K. Bailey, Biochem. J . , 1935,29, 2351 ;A., 1433242 CRYSTALLOQRAPHY,LIQUIDS.It is impossible for reasons of space to include in this section allthe modern developments in the theory of liquids. All that can bedone is to give some references to recent papers on the determinationof the statistical structure of certain liquids by means of X-rays.S. Ka'tzoff S5 has studied water, heptane, decane, benzene, andcyclohexane : in water, a tetrahedral arrangement was found ; 86 inthe others, a statistical close packing of chains or quasisphericalmolecules. B. E. Warren *' has made a Fourier analysis of liquidparaffin and shows that it can be represented by parallel zigzagchains at an average distance of 5.0 A. apart.W. H. Zachariasen88 has shown that in liquid methyl alcoholthere is evidence for hydroxyl bonds. J. A. Prins has studiedthe diffraction of ionic solutions,89 and been able to show that asecondary lattice depending on the concentration exists in some,but not all, ionic solutions.The question of cybotactic groups has been much studied,especially by Stewart and his co-workers.QO Evidence is stillconflicting. These groups almost certainly do exist in long-chainalcohols, but their presence in ethyl ether in the region of the criticalpoint has been disputed by N. S. Gingrich and B. E. Warren,g1who show that the observed diffraction can be explained simplyby a statistical arrangement of a certain mean distance. It isinteresting to note that the diffraction pattern given by liquids inthe neighbourhood of the critical point depends only on the volume,and is practically identical at two temperatures above and belowthe critical temperature when these have the same volume.H. Sirk 92 has shown, by unsuccessful attempts to induce magneticorientation, that the cybotactic group in a hydrocarbon cannotcontain more than 10,000 molecules. J. D. B.J. D. BERNAL.D. M. CROWFOOT.R. C. EVANS.A. F. WELLS.J . Chern. Physics, 1934, 2, 841; A., 1935, 152. Compare H. K. Ward,ibid., p. 153; A., 1934, 587; W. C. Pierce, ibid., 1935,3, 252; J. A. Prins andR. Fonteyne, Physica, 1935,2, 573.8 7 Physical Rev., 1933, [ii], 44, 969; A., 1934, 244.8 8 J . Chern. Physics, 1935, 3, 158.89 Ibid., p. 72; J . A. Prins and R. Fonteyne, Physica, 1935, 2, 570; J. A.Prins, ibid., 1934,1, 1171; A., 1935, 162.9* G. W. Stewart, J . Chern. Physics, 1934,2,147 ; A., 1934, 591 ; C. A. Benzand G. W. Stewart, Physical Rev., 1934, [ii], 46, 703; R. D. Spangler, ibid.,p. 698; ibid., 1932, [ii], 42, 907; A., 1933, 1236.Ibid., 1934, [ii], 48,248; A., 1934, 1160.82 8. Physik, 1934,89.129; A,, 1934, 834.86 See Ann. Reports, 1934, 31, 86

ISSN:0365-6217    

DOI:10.1039/AR9353200181

出版商:RSC    

年代:1935

数据来源: RSC

摘要:

ORGANIC CHEMISTRY.1. STEREOCHEMISTRY.ONE of the ambitions of all stereochemists has been rcalised byP. Maitland and W. H. Mills,l who have shown that an allene canexhibit the optical activity required of it by established theory.They dehydrated ay-diphenyl- ay-di- 1 -naphthylallyl alcohol (I)with d- and with Z-camphor-10-sulphonic acid and obtained d-and Z-diphenyldinaphthylallene (11), the specific rotations (A 5461)having the surprisinglyetc.etc.Annalen, 1935, 520, 11; A , , 1378TURNER : HETEROCYCLIC COMPOUNDS. 345(XLI) was obtained either from 5-ethoxytryptamine and p-toluene-sulphonyl chloride or by the action of alcoholic zinc chloride andp-ethoxyphenylhydr azine on y -p -toluenesulphonamido but aldehydediethyl acetal (XL). Methylation then gave the N-methyl deriv-ative, which was alternatively obtained from y-p-toluenesulphonyl-met h ylamido bu taldeh yde die thy1 ace tal and p -e thoxyphenyl-hydrazine. Removal of the toluenesulphonyl group by the use ofaniline and aniline hydrochloride gave 5-ethoxy-N-methyltryt-amine, which, with ethylmagnesium iodide, followed by methyliodide, gave isonoreserethole.The hydrochloride of this wasconverted by methyl iodide into dl-eserethole.The same authors have also carried out the synthesis of bufotenine(XLII) from 5-ethoxyindole-3-acetonitrile, the CH,*CN group beingsuccessively converted into CH,*CO,H, CH,*CO,Et, CH,*CH,*OH,CH,*CH,Br, and CH,*CH2*NMe, by usual methods. The finalproduct gave bufotenine when de-ethylated with aluminiumchloride.Ergot A ZEaZoids .-Our knowledge of these alkaloids has increasedconsiderably in the last few years.For an account of the olderwork, reference may be made to a paper by S. Smith and G. M.T i m m i ~ . ~ ~ The work of Barger, Dale, Cam, and Kraft showedthat ergotoxine and ergotinine were isomeric and interconvertible,boiling methyl alcohol changing ergotoxine into ergotinine, and hotdilute alcoholic phosphoric acid solution effecting the reverse change.A. Stoll56 isolated a third alkaloid, ergotamine, which underwentisomeric change into a fourth alkaloid, ergotaminine, under con-ditions similar to those .governing the ergotoxine-ergotinine con-versions. This suggested a close relationship between ergotoxineand ergotamine, which was supported by the observation 67 that thephysiological actions of these two bases were qualitatively andquantitatively identical ; according to other aufhors,5* ergotoxinehad a biological activity 1.66 times that of ergotamine.Smithand Timmis, in the above paper, described the isolation of allfour alkaloids in a state of high purity, and, by examining ergot5 5 J., 1930, 1390; A., 1930, 1050.66 Schweiz. Apoth.-Ztg., 1922, 60, 341 ; A., 1923, i, 127; see also K. SpiroRnd A. Stoll, Verh. Schweix. Nat. Gw., 1920; A., 1922, i, 47.57 H. H. Dale and K. Spiro, Arch. exp. Path. Phapm., 1922, 95, 337; A.,1923, i, 420.5 8 E. Lozinski, G. W. Holden, and (2. R. Diver, J . Pharm. Exp. Y'her.,1931, 42, 123; A,, 1931, 871346 OMANICJ CHEMISTRY.from seven different European sources, they concluded that ergotof rye contains only ergotoxine and ergotinine, though a NewZealand ergot growing on Pestuca contained ergotamine. In 1931,59they recorded the isolation of a new alkaloid, +-ergotinine, probablyisomeric with ergotoxine.A.Soltys60 showed that all four alkaloids on treatment withboiling alcoholic alkali gave one molecule of ammonia, and thatoxidation of any of the alkaloids by permanganate and by nitricacid produced benzoic and pnitrobenzoic acid, respectively.Smith and Timmis,G1 following up this work, isolated a new,optically active base, ergine, Cl6Hl,ON3, by heating any of thefour alkaloids with alcoholic potassium hydroxide.At this point, an outstanding series of papers by W.A. Jacobsbegan to appear. He found G2 that nitric acid oxidation of ergotininegave also a tribasic acid, possibly C,,H,08N, and, with L. C. Craig,G3showed that ergotinine and methyl-alcoholic potassium hydroxidegave (1) an acid, Cl,W12N(NMe)*C0,€€, named lysergic acid, (2)isobutyrylformic acid, and (3) ammonia, whereas, on similar treat-ment, ergine gave an acid which was at first thought not to belysergic acid but mas later identified as the acid sulphate of thissubstance. Smith and Timmis, however, showed 64 that erginewas the amide of an acid, C15Hl,N,*C0,H, probably lysergicacid.cJacobs and Craig found that lysergic acid was reducible withsodium and amyl alcohol to dihydrolysergic acid,65 and thatergotinine,G6 when reduced with sodium and n-butyl alcohol, gave,in addition to one molecule of ammonia, seven products : (1)a-dihydrolysergol, ~16H2,0N2, containing m e and forming amonoacetyl derivative ; (2) p-dihydrolysergol ; (3) cc-hydroxyiso-valeric acid (formed from isobutyrylformic acid) ; and four bases,numbered 11, IV, V, and VI.Since reduction of methyl lysergategave (1) and (2) but none of the other products, it follows that thefour bases arise from that part of the ergotinine molecule which isnot lysergic acid, the two portions of the molecule possibly beingjoined by means of the isobutyrylformic acid skeleton. Theformation of two dihydrolysergols is possibly due to the introductionof a new centre of asymmetry during the reduction of lysergic acid.68 J . , 1931, 1888; A., 1931, 1171.6O Ber., 1932, 65, [B], 553; A., 1932, 629.61 J., 1932, 763, 1543; A., 1932, 526, 759.62 J.Biol. Chem., 1932, 97,739; A., 1932, 1147.63 Ibid., 1934, 104, 547; A., 1934, 538.64 Nature, 1934,133,579; A., 1934, 667; J., 1934, 674; A., 1934, 787.6 5 J . Biol. Chern., 1934,106, 393; A., 1934, 1116.66 Ibid., 1935, 108, 595; A., 504TURNER : HETEROCYCIJC COMPOUNDS. 347Later work G7 on the above four bases showed that base VI wasa phenylpropanolamine, suggesting phenylaJanine as its precursorin ergotinine. The same authors also identified, as a componentof the above reduction mixture, proline methyl ester, which wasalso formed by the action of methyl-alcoholic hydrogen chlorideon ergotinine. Bases I1 and IV were probably piperazine deriv-atives formed by reduction of prolylphenylalanine anhydride andproline anhydride respectively, and base V, probably a-pyrrolidyl-carbinol, was derived from proline or its ester. This showed thatergotinine, and therefore ergotoxine, are built up of lysergic acid,Cl,Hl,OzN, (or its amide, ergine, C16H170N3), proline, phonyl-alanine, and isobutyrylformic acid.Addition of these fragmentswith removal of four molecules of water gives C35H3905N5, whichis the empirical formula of ergotinine. At this point, Jacobs andCraig thought that lysergic acid, the pharmacologically importantcomponent of the alkaloids, was joined to a dipeptide composedof proline and phenylalanine.These authors G8 also made a preliminary study of ergotarnine.This was shown to give rise to lysergic acid, ammonia, and phenyl-alanine, but proline was not definitely identified.One importantdifference between ergotarnine and ergotinins was discovered :none of the degradation processes used led to the formation ofisobutyrylformic acid or of its reduction product, a-hydroxyiso-valeric acid. Since in empirical formula the two alkaloids differby CzH4, it was thought that in ergotamine (and ergotaminine)pyruvic acid might take the place of isobutyrylformic acid inergotinine.G. Barger,cQ who, with A. J. Ewin~,~O first obtained isobutyryl-formamide by the thermal decomposition of ergotoxine and ergo-tinine, obtained this amide, and ergine, from the ergoclavinedescribed by W. Kiissner. 71 Jacobs and Craig 72 found that ergotinine,when heated with hydrochloric acid, gave Z-phenylalanine and prolinemethyl ester, whereas similar treatment of ergoclavine, alkalinehydrolysis of which gave ammonia, lysergic acid, and isobutyryl-formic acid, gave Z-leucine but no proline.Development of thework on the alkaline hydrolysis of ergotinine 63 led t o the isolation,in addition to lysergic acid and isobutyrylformic acid, of a mixture,acid hydrolysis of which gave almost inactive proline and phenyl-Evidence for this was actually found.6 7 J . Amer. @hem. SOC., 1936, 57, 383; A., 504.f18 Science, 1935, 81, 256 ; A., 764.O9 Merck's Jahresber., 1933, 47, 12.7o J., 1910, 97, 290.71 Merck's Jahraber., 1933, 47, 5.72 J . Amer. Chern. SOC., 1935, 5'7, 960; A,, 872.73 J .BioZ. Chem., 1935, 110, 521; A., 1137348 ORQAMC CHEMISTRY,alanine. Hydrolysis of ergotinine with hydrochloric acid, however,gave Z-phenylalanine, what appeared to be a proline-phenylalaninedipeptide, and also d-proline methyl ester. Whiht, therefore, thephenylalanine has the usual configuration, that of the proline isunique in this instance, and, of course, a Walden inversion toexplain it is probably out of the question. This confirmed theformer conclusion that ergotinine and ergotoxine are composed ofproline and phenylalanine combined in peptide linkage with lysergicacid, isobutyrylformic acid, and ammonia.In their most recent paper,'* Jacobs and Craig show that all theergot alkaloids are derivatives of lysergic acid, in which the latteris conjugated with a-amino-acids or with substances derived fromthem.A return was made to dihydrolysergic acid, which washeated with potassium hydroxide at 300" in an atmosphere ofhydrogen. The products were : (1) methylamine, (2) a substancewhich was probably 2-methyl-3-ethylindole, (3) propionic acid,and four other substances. It being known that by reductionwith sodium and butyl or amyl alcohol lysergic acid gives a dihydro-derivative, and that ergotinine or methyl lysergate gives thecorresponding alcohol (as a- and P-dihydrolysergols), and that it isM c u l t to reduce an indole structure, it becomes highly probablethat at least one ethylenic linkage is present in another part of themolecule. This suggests a 4-carboline structure, and, since methyl-amine is formed almost quantitatively in the above decomposition,the basic carboline nitrogen atom probably carries the methylgroup and is the salt-forming part of the molecule.This gives thepartial structure (XLIII). To make up the 16 C of lysergic acid,there are also required a propyl or propylene side chain and acarboxyl group, these presumably being attached to the reducedring. Further, the lysergic acid molecule has two double bonds.CH CH,CH:CMMe CHXHMe(XLIII. ) (XLIV.) (XLV.)One is readily reduced and is probably a t C5-C, (compare harmineand harmaline giving tetrahydroharmine). The inferred relation-ship to tryptophan places the carboxyl a t C5, so lysergic acid wouldbe (XLIV). This formula accounts for the optical activity, andexplains the formation of the epimeric dihydrolysergols (XLV)from either ergotinine or methyl lysergate, since a new centre of74 J .Biol. Chem., 1935, 111, 465; A . , 1512TURNER : HETEROCYCLIC COMPOUNDS. 349asymmetry appears at C5. The second double bond must be, asshown, in the side chain, but the latter may be an ally1 group,undergoing the common bond-shift during alkaIi fusion. If boththe carboxyl and the propenyl group are at C,, it is more difficultto explain the epimeric dihydrolysergols. It may be observed thata-dihydrolysergol was shown to give a true onium salt with methyliodide.A surprising new chapter in ergot chemistry was opened byH. W. Dudley and C. M0ir,7~ who showed that the characteristicoxytocic effects of ergot were due, not to ergotoxine or to ergotamine,as had been thought, but to a new alkaloid, ergometrine, the extrac-tion of which, by an improved method, was described by Dudley.76M.R. Thompson 77 also obtained evidence that there was a newalkaloid in ergot other than ergotoxine or ergotamine. Again,M. S. Kharasch and R. R. Legault 78 isolated “ ergotocine” fromergot, and showed that under condit’ions (hot alkali) such as gaveone molecule of ammonia with ergotoxine, ergotamine, and “sen-sibamine ” (see below), no ammonia was formed. Lysergic acidwas the only product identified. The “ ergobasine,” C,,H,,O,N,,isolated from ergot by A. Stoll and E. Burckhardt 7, was shownto be lysergic hydroxyisopropylamide.80 M.R. Thompson 81expressed the ‘‘ belief ” that ergostetrine (his new alkaloid) wasidentical with ergometrine, ergotocine, and ergobasine, and H. W.Dudley 82 put forward the same view more definitely.=CH/\-/ I It II ~~*CO*NH*CHMe*CH,*OH\/\A / m e (XLVI.1NH QHCHXHMeThe validity of the arguments of Jacobs and Craig being assumed,S. Smith and G. M. the constitution of ergometrine is (XLVI).7 5 Brit. Med. J., 1935, i, 520; A., 655.7 6 Pharm. J., 1935,154, 709; A , , 894.7 7 J . Amer. Pharm. ABSOC., 1935, 24, 24, 185; A., 894.7 8 J . Amer. Chem. SOC., 1935, 57, 956, 1140; A., 872, 995.79 Compt. rend., 1935, 200, 1680; A., 995.80 W. A. Jacobs and L. C . Craig, Science, 1935, 82, 16; A., 1137.81 J . Amer. Pharm. ASSOC., 1936, 24, 748; A., 894.62 Proc.Roy. SOC., 1935, [B], 118, 478; A., 1512.83 See also H. W. Dudley and C. Moir (Science, 1935, 81, 559; A., 1157);M. S. Kharasch and R. R. Legault (ibid., p. 614; A., 1157); M. R. Thompson(ibid., p. 636; ibid., 82, 62; A., 1157); N. L. Allport and S. K. Crews (Quart.J . Pharm., 1935,8,447 ; A., 1512) ; and E. C . Kleiderer ( J . Amer. Chem. SOC.,1935,57, 2007; A., 1512). As far as the writer is aware, the present accountof ergot chemistry includes all references since 1930, up to December, 1935360 ORQAXIC UHEMISTRY.Timmis 84 have isolated yet another ergot alkaloid, ergometrinine,isomeric with, and convertible into, ergometrine, these two alkaloidsbeing related in the same manner as ergotoxine-ergotinine andergotamine-ergotaminine.The identity of $-ergotinine 59 remainsunexplained.It is possible now to summarise the present position as follows :Active Alkaloids. Inactive Alkaloids. Components.Ergotoxine Ergotinine Lysergic acid}ErgineAmmoniaProlinePhen ylalanineisoButyrylformic acidC,,H,,O,N5Ergotarnine Ergotaminine Lysergic acid}ErgineAmmoniaProline ?%H3,O,%Pheny lalaninoPyruvic acidErgometrine Ergometrinine Lysergic acidp- Aminopropgl alcohol(Hydroxyisopropylamine) C19H2302N3The first four alkaloids give the same ergine, which is the amideof lysergic acid. Ergometrine, and presumably ergometrinine,give the same lysergic acid. It follows that the isomerism betweenthe active and the inactive alkaloids must reside in the lysergicacid portion of the molecule.If the Jacobs-Craig formula forlysergic acid is correct, it would seem to follow that the isomerismmust be due to cis- and trans-arrangements around the doublebond in the side chain, although this is not altogether satisfactory,considering the conditions under which the isomeric changes occur.(Sir) H. H. Dale pointed out s5 that the pharmacological activitiesof ergoclavine and sensibamine were identical with those of ergo-toxine and ergotamine.86 A. $toll 87 showed that sensibamine wasnot a definite C31E1&5N5y but was a molecular com-pound, C33H,505N,,C3,H,,05N5, of crgotamine and ergotaminine.Ergoclavine is also probably a mixture, but it should be recalledthat Z-leueine was obtained by Jacobs and Craig 72 as one of itsdegradation products , and it is therefore possible that ergoclavine,which has been given the formula C31H37Q5N5, is actually a mixture,one component of which is an undiscovered alkaloid, C31H3,03N5or C31H3502N5, built up from erginc, 2-leucine, and phenylalanine.Admitting that the constitution assigned to lysergic acid byJacobs and Craig was not intended by them to be taken as h a l ,it is not without interest to attempt to picture the possible structure84 Nature, 1935, 136, 259; A., 1256.8 6 Schweiz. med.Woch., 1935, 65, 585.A. Vartiainen, J . Pham. Exp. Ther., 1935, 54, 259.Schweix. med. Woch., 1936, 65, 1077TURXER : HETEROCYCLIC COMPOUNDS. 361of the alkaloids.corresponds to a structure such as (XLVPI) or (XLVIII).The known chemistry of ergotoxine and ergotinineIn ergotarnine and ergotaminine, the group CO*CO*CHMe, wouldbe replaced by CO-CO*CH, (XLVIII) ; in (XLVII) CO*C(OH)*CHMe,would be replaced by *CO*C(OH)Me.Curare Alkaloids (South American Arrow Poisons) .-An in-vestigation of more than usual interest is that of the curare alkaloidsby H.King,*g who has obtained Boehm’s tubocurarine in a,crystalline condition, and submitted it to degradation processes,Curine, the crystalline alkaloid accompanying tubocurarine, wasCH,:CH\/OMeshown by E. Spgth, W. Leithe, arid P. Ladeck 89 to be the lava-modification of d-bebeerine. H. King 90 suggested a probableformula, for curine, which was supported by the experimental88 Chem. and Ind., 1935, 739; A., 1138.Ber., 1928, 61, [B], 1705; A., 1928, 1264.Ann.Reports, 1933, 30, 249352 ORGANIC CHZMISTRY.work of E. Spath and F. Kuffner,gl who assigned to O-methylcurinethe structure (I). King has now 92 carried out the exhaustivemethylation of the accessible base, d-curine (d-bebeerine), obtainingin this way the known O-methylbebeerine methochloride. Hofmanndegradation of the latter gave three distinct methine bases, andthence three crystalline methiodides. Hofmann degradation ofthe mixture of the three methochlorides gave trimethylamine anda substance, C3GH320G. Similar degradation of d-O-methyltubo-curarine chloride led to a mixture of four methine methiodides,three of which were identical with the above three methiodides,the fourth being Z-0-methyltubocurarinemethine methiodide.Thesecond degradation stage gave trimethylamine and the substanceC,GH320,. If O-methylbebeerine is regarded as (I), the lattersubstance can be accounted for as (11). It is probable, however,that although O-methylbebeerine methochloride and O-methyl-tubocurarine methochloride are diastereoisomerides, the parentphenolic substances, bebeerine methochloride and tubocurarinemethochloride, have different arrangements of hydroxyl andmethoxyl groups.Dauricine.-The constitution of this alkaloid has been proved 93by a synthetic method, methyldauricine-a-methine (111) beingobtained as follows :Me C0,HM e o - 0 9 -+ CO,H(-?-O--IC) \Me I Me0CHO J COClCHO<>-O-C> c-- COCl@---Me0 I J.AzlactoneCH,*C02H-+ C0,M*C,H2CK2Dihomo- PCI,; H,O; Hal; H.Me0CH9 193Ber., 1934, 67, [B], 55; A., 1934, 312.H. Kondo, Z. Narita, and S. Uyeo, Ber., 1935, 68, [B], 619; A., 637.92 J., 1935, 1381353From this it follows that dauricine has the constitution (IV) sug-gested by F. Faltis and H. Frauendorfer.94TURNER : HETXROCYCLIC COMPOUNDS.Phaeanthine.-Whereas A. C. Saiitos 95 found this alkaloid tobe C3,H3806N2, H. Kondo andI. Keimatsu 96 find it to be C,8H420,N2,and a comparison of its physical properties with those of tetrandrinesuggested that these two alkaloids are optical antipodes. Theabsorption curves support this view.97 Probably tetrandrine,isotetrandrine, and phaeanthine represent three out of the fourpossible stereoisomerides corresponding to the two asymmetriccarbon atoms in (V) and (VI), which are the two possible structuralformula for the alkaloids : 9894 Ber., 1930, 63, [B], 809; A., 1930, 774.95 Ber., 1932, 65, [B], 472; A., 1932, 527.96 Ber., 1935, 68, [B], 1503.97 H.Kondo and I. Keimatsu, J. PhaTm. SOC. J a p n , 1935, 636.98 F. von Bruchhausen, H. Oberembt, and A. Feldhaus, Alzrzalen, 1933,507, 144; A., 1933, 1313.REP.-VOL. XXXII. &354 ORGANIC CHEMISTRY.Sophora Alkaloid.-H. Kondo, E. Ochiai, and K. Tsudag9 havealmost completed their investigation of the constitution of matrine,one of the principal alkaloids in the roots of Sopbra jlavescens.The alkaloid, which is not a stereoisomeride of lupanine, is probablyeither (VII) or (VIII).MeyH-yO Me? H-YH,CH, N CO CH(VIII.))6'bH2 'Nf )H2(VII.) CH CH bH CH/\/ 7% d p 2CH, N CH,& 2 ) G \ p 2\/\/ CH, CH, kH2'\CG2CH, N CH,LactoJlavin.Last year, R.Kuhn, R. Reinemund, and F. Weygand describedthe synthesis of lumilactoflavin (11) by a modification of the Kuhlingcondensation. P. Karrer, H. Salomon, K. Schopp, E. Schlittler,and H. Fritzsche 2 showed that, if lactoflavin (vitamin-B,) isirradiated, not in strongly alkaline solution (when lumilactoflavinis produced), but in dilute methyl-alcoholic solution, lumichrome(I) (6 : 7-dimethylalloxazine) is formed, and they suggested thatlactoflavin probably contained a pentose chain, CH,*C,H,O,, inposition 9. In a later paper 3 the two decompositions induced byirradiation were pictured thus :( b )N NH CH2-i-E CH*OH],*CH,* OH(a)---!--,(4 q)$>O~~ N CO f- ::QjvNH ,kA-\yo (111.)(1.1 N CO$(b)99 Ber., 1935, 68, [B], 1899; A., 1514.Kondo's papers on matrine may be found in A abstracts.been abstracted.Ber., 1934, 67, [BJ, 1460; A., 1934, 1114.Parts I to IV and XV to XVII ofThe rest have not2 Helv. Chim. Acta, 1934, 1'7, 1010; A., 1934, 1233.P. Karrer, H. Salomon, K. Schopp, and E. Schlittler, ibid., p. 1165; A.,1934, 1233TURNER HETEROCYCLIC COMPOUNDS. 355and the following synthesis of an analogous but less complexsubstance was described :CH,*CH(OH)CH2*oH ::ofo2 + NH,*CH,*CH(OH) -+ MeCH,*OH---+-alloxan J.I,1H,-CH( OH)*CH,*OHNSince the simpler product closely resembled lactoflavin, the aboveconstitution (111) for the latter was supported.At approximatelythe same time, R. Kuhn and F. Weygand,* starting with Z-arabinoseand d-xylose, synthesised in the following manner, two compounds(111), both of which resembled lactoflavin in solubility, absorptionspectrum, and dependence of fluorescence on pH, formed a redradical when reduced in mineral acid solution, and gave lumilacto-flavin when irradiated in alkaline solution : ZZGfo2 + NH,*CH,*[CH-OH],*CH,*OH -+ Nitro-compoundAlloxan I * (111) t- I [Amino-compound]P. Karrer and K. Schopp, who had already described the isolationof a flavin from green malt, later showed that irradiation ofcrystallised ovoflavin-e from dry technical ovalbumin gave 6 : 7-dimethylalloxazine. R. Kuhn and F. Weygand pointed outthat there were eight possible stereoisomerides corresponding toformula (111) above, and expressed the view that lactoflavin wasmost probably the Z-arabo- or the d-ribo-compounds (111).Thesame authors 9 had previously stated that the I-arabo-compoundhad the same growth-promoting effect as natural lactoflavin, a tthe same time showing that the corresponding compound devoidof the two methyl groups in one nucleus was inactive in that respect.Ber., 1934, 67, [B], 1939; A . , 1935, 224.Helv. Chim. Acta, 1934, 17, 1013; A., 1934, 1233.Ibid., p. 1557; A , , 1935, 95.Ber., 1935, 68, [B], 166; A., 358.Compare R. Kuhn and H. Rudy, ibid., p. 169; A., 369.Ber., 1934, 67, [B], 2084; A., 1935, 262356 ORGANI$ CHEMISTRY.A different type of synthesis was introduced by P.Karrer, K.Schopp, F. Benz, and K. Pfaehler,lo who found that, whereas thecondensation of o-chloronitrobenzenes with amino-sugars was notparticularly satisfactory, good results in the preliminary stages wereobtained by the reductive condensation of the monoacetyl deriv-ative of o-phenylenediamines with aldoses :qH,*OHCH,*[CH*OH],@2Ac + OCH*[CH*OH],*CH,*OH + ( 3 g A cBy this method, these authors synthesised Kuhn’s Z-arabo-com-pound (111), and they too thought that the latter might be identicalwith natural lactoflavin, the observed differences possibly beingdue to impurities in the natural product.At this stage, R. Kuhn and H. Kaltschmitt 11 showed that thelactoflavin isolable as the tetra-acetyl derivative from Californianlucerne was identical with milk lactoflavin. It may be notedthat, according to L.J. Harris,12 Kuhn’s lactoflavin had no anti-pellagra action, and in this view he was supported by P. GyOrgy.l3Yet B. C. P. Jansen 1 4 regarded the identity of lactoflavin andvitamin-B, as established.Shortly after this, P. Karrer, I<. Schopp, and F. Benz l5 describedthe synthesis of two compounds of formula (111), one being the d-xylo-compound obtained by Kuhn and WeygandY4 the other a newsubstance, 6 : 7-dimethyl-9-d-l’-ribitylisoalloxazine (I11 ; IV), whichresembled natural lactoflavin extremely closely, the tetra-acetylderivatives also being very similar. In a paper sent in five dayslater than that by Karrer and his co-workers, R. Kuhn, H. Rudy,and F.Weygand l6 definitely expressed the opinion that 6 : 7-dimethyl-9-Z-araboflavin could not be identical with lactoflavin,since it was at least three times less effective than the latter ingrowth-promoting activity. These authors further said thatlactoflavin was possibly the d-ribo-compound (I11 ; IV), andannounced a new type of synthesis of the d-arabo-compound,starting from 4 : 5-dinitro-o-xylene :lo Ber., 1935, 68, [B], 216; A., 359.l1 Ibid., p. 128; A., 415.l2 Biochem. J., 1935, 29, 776; A., 545.Ibid., p. 741 ; A,, 646.l4 Nature, 1935, 135, 267; A., 545.Helv. CZ~irn. Acta, 1935, 18, 426; A., 631.l8 Ber., 1935, 68, [B], 625; A., 760TURNER : HETEROCYCLIC COMPOUNDS. 357QH2*OHIH0.Q.HH0.C.HHO+H -5.(111)6 : 7-Dimethyl-9-Z-araboflavinalloxazine (Karrer) .(Kuhn) = 6 : 7-Dimethyl-9-l-l’-arabityliso-Other workers17 confirmed the identity of the riboflavin withlactoflavin, and showed that most other synthetic flavins (xylityl,rhamnityl, sorbityl, dulcityl, and mannityl) had no biologicalactivity, although the Z-araboflavin had some. They also pointedout that lactoflavin is the growth-promoting substance present invitamin-B,, but is not necessarily the anti-pellagra factor, and thiswould explain the results of C. A. Elvehjem and C. J. Koehn.lsAt the same time, Karrer and his co-workers17 described the re-ductive condensation of d-ribose with the mono-urethane derivedfrom 4 : 5-diamino-o-xylene as an alternative first stage in theflavin synthesis.In order further to remove doubt as to the identity of lactoflavin,the antipodal varieties of d-ribo- and Z-arsbo-flavins were prepared.l9It was found that Z-riboflavin bad no growth-promoting action.An interesting point was also discovered by the same authors,CH,*[CH~OH],*C€12*OHA Nnamely, that 7-methyl-9-d-l’-ribitylisoalloxazine (V) had strongvitamin-B2 action ; the o-xylene structure, therefore, is not essential1 7 H.von Euler, P. Karrer, M. Malmberg, K. Schopp, F. Benz, B. Becker,and P. Frei, Helv. Chim. Acta, 1935, 18, 522; A . , 760. See also P. Karrer,H. von Euler, M. Malmberg, K. Schopp, and F. Benz, Svensk Kern. Tidskr.,1935, 47, 99; A., 1286.18 J . Biol. Chern., 1935, 108, 709; A., 669.1@ P. Karrer, H. Salomon, K. Schopp, F. Benz, and B. Becker, Helv.Chim.Acta, 1936,18,908; A., 1134358 ORUANIC CHEMISTRY.HO--HHO--HHO--Hfor the latter. Later 2o they described the synthesis of the eighthand last possible compound of structure (111), uix., 6 : 7-dimethyl-9-d- 1’-lyxitylisoalloxazine, this establishing finally the configurationof the sugar residue in lactoflavin. Examination21 of the fluor-escence spectra of several synthetic flavins further confirmed thesame point.R. Kuhn and F. Weygand22 found that the yield of flavinsobtained by condensing sugar derivatives of o-diamines withalloxan is enormously improved if boric acid is used instead ofhydrochloric acid as the condensing agent, moderately anhydroussolvents being beneficial. For instance, when the N-arabitylderivative of diaminoxylene was treated with zinc dust and boricacid in boiling glacial acetic acid, followed by addition of alloxan,a 52% yield of the flavin was formed. Even with 2-aminodiphenyl-amine and alloxan under these conditions a 63% yield of 9-phenyl-isoalloxazine may be obtained.Another interesting flavin synthesis is due to P.Karrer andH. F. Meer~ein.~3 o-4-Xylidine was reductively condensed withd-ribose in presence of nickel or palladium, the product (VI) coupledwith diazotised p-nitroaniline, the azo-derivative catalyticallyreduced under high pressure in presence of nickel, and the resultingbase condensed with alloxan :CH2*[CH*OH],*CH2*OHCH2*[CH*OH]3*CH,*OHMe MeK:*c.,,,,,,IIn a summary of their work, Kuhn and his collaborators24 stressthe advantages of their synthetic methods, particularly (1) the use20 P.Karrer, H. Salomon, K. Schopp, and F. Benz, Naturzuiss., 1935, 23,21 P. Karrer and H. Fritzsche, Helv. Chim. Acta, 1935, 18, 911 ; A., 1134.2 2 Ber., 1935, 68, [B], 1282; A., 1134.23 HeEv. Chim. Acta, 1935, 18, 1130; A., 1510.24 It. Kuhn, I<. Reinemund, F. Weygand, and R. Strobele, Ber., 1935,355; A., 993.68, [B], 1765; A., 1382LINSTEAD : THE PORPHYRIN GROUP. 359of palladium and not nickel for reductive condensations (Karrer’smethod necessitating the employment of high pressures), and (2)the use of boric acid in the final stage, yields of 90% being recordedwith d-riboflavin : condensation of N-d-ribityldiaminoxylene withalloxan was carried out in glacial acetic acid solution a t the ordinarytemperature.An account of some of the work on lactoflavin was given in alecture by R.K ~ h n . ~ ~ I n this it is suggested that the parentyellow plant enzyme corresponding to lactoflavin is (VII). Thisacid, in the form of its sodium salt, was prepared26 by treatinglactoflavin with phosphoryl chloride in presence of pyridine.E. E. T.8. THE PORPHYRIN GROUP.^General.Great advances have been made during the last few years inthe chemistry of this group, which constitutes probably the mostimportant class of natural organic colouring matters and is of thegreatest biological interest.2 Developments in the study of hzeminand associated compounds have already been r e p ~ r t e d . ~ Thechemistry of chlorophyll is reviewed below, together with that ofother natural porphyrins.The biological importance of the porphyriiis tends to obscuretheir great chemical interest.Before considering in detail thenatural pigments, we may briefly examine the peculiarity ofthe common structural unit. It is now generally believed that theporphyrins contain the basic unit porphin (A): as was first proposedby W. Kuster for the blood pigment. The synthesis of this parentsubstance in very poor yield was achieved by Hans Pischer, aftermuch negative workJ5 by heating pyrrole-2-aldehyde with alcoholin boiling formic acid. The substance is a typical porphyrin in itsgeneral properties, notably in its spectrum. The free compoundhas a five-banded spectrum with two sharp bands in the green region ;the copper compound has the usual two-banded spectrum of the25 Bull.SOC. Chirn. biol., 1935, 17, 905.26 R. Kuhn and H. Rudy, Ber., 1935,68, [B], 383; A., 545.1 The term should be read to include the free porphyrins, their metallic2 A. Treibs’s recent discoveries of porphyrins in petroleum and coal have3 Ann. Reports, 1932, %, 209.4 F. Hrturowitz and his associates have proposed a free-radical variant of5 H. Fisuher and W. Gluin, Annalen, 1936,521, 157.derivatives, and substances of similar cyclic structure.given the group a geochemical significance also (see p. 398).this (Ber., 1935, 68, [B], 1795; A., 1384)360 ORUANIC CHEMISTRY.metallic porphyrins, and the iron compound gives a typical haemo-chromogen spectrum on treatment with hydrazine.Simple deriv-atives such as octamethylporphin (with methyl groups on theP-positions of the pyrrole rings) have been known for some time.The Kiister formula was not a t first accepted, for, as Willstatterpointed out, it contained a 16-membered ring of a type withoutparallel. The evidence in its support comes mainly from thesynthetic work of H. Fischer.’ The syntheses of porphyrins bythe condensation of 3 : 4-dialkylpyrroles (such as opsopyrrole),with formaldehyde or formic acid,8 and by the fusion of 2 : 2‘-dibromodipyrrylmethenes with 2 : 2’-dimethyldipyrrylmethenes insuccinic are of particular value as indicating the structure.[The positions of the imino-hydrogen atoms and the double bonds in theseformulae are arbitrary.]All these synthetic methods, however, involve a loss of hydrogenill the final condensation, apart from the hydrogen bromide orwater, etc., eliminated between the condensing groups, and noneprovides a h a 1 proof of structure; nor, from the very complexityof the molecule, is this to be expected.On the other hand, thecumulative evidence is very strong, and the Kiister formula notonly accounts for all the reactions of porphyrins, but also providesa satisfactory basis for Fischer’s important investigations of theirisomerism .3The recently discovered phthalocyanines 10 throw some lighton the problem. The formula (B) given to phthalocyanine on6 H. Fischer and B. Walach, Annalen, 1926, 450, 164; A., 1926, 1261.7 H. Fischer and co-workers, ibid., 1926, 448, 178, 193, etc.; A., 1926, 962,963; particularly 1928, 462, 240; A., 1928, 902.Cf. Ann. Reporb, 1932,29, 209.* H. Fischer and A. Treibs, Annalen, 1926, 450, 132; A., 1926, 1266;Ber., 1927, 60, 379; A., 1927, 365.a H. Fischer, P. Halbig, and B. Walach, Annalen, 1927, 452, 268; A.,1927, 469.lo R. P. Linstead, J., 1934,1016; A., 1934, 1114LINSTEAD THE PORPHYRIN GROUP. 361chemical evidence l1 has been confirmed by J. M. Robertson’sX-ray examination.12 The molecular weight l3 and the dimen-sions l2 have been determined and the structure is certain (apartfrom detail of the fine structure). The entry of a metallic atom hashardly any effect on the size of the molecule.12 Phthalocyaninecontains a central 16-membered ring of a type essentially similarto that postulated for the porphyrins (but containing 4 -N= for4 -CH=) and resembles the latter in many physical and chemicalproperties.ll There is no doubt, therefore, that stable rings ofthis type can exist and the Kuster formula is strongly supported bythe resemblance .14When these large rings are present the chemistry of the moleculeis profoundly modified; e.g., phthalocyanine shows none of theordinary instability of an isoindole derivative, nor a porphyrinthat of a pyrrole.There is in fact an approach to an aromaticcharacter, presumably arising from the formation of the unbrokenconjugated ring. This is seen in the tendency to formation and inthe great stability of the type. The porphyrin nucleus survivesthe most diverse chemical treatment.Unlike almost all othercoloured organic compounds, porphyrins are not reduced by alkalinehyposulphite or by hydrogen over palladium in alkaline s01ution.l~They are reduced by more drastic reagents, but are readily regener-ated from the leuco-compounds (Fischer, R. Kuhn, Conant).Porphyrins can be halogenated,lG* l7 nitrated,l7. l8 and s~lphonated.~~The stereochemistry of both phthalocyanine and the porphyrinsis essentially aromatic ; the phthalocyanine ring has been provedexperimentally to be flat 12 and porphyrins show no optical activity.2011 C. E. Dent, R. P. Linstead,and A. R. Lowe, J . , 1934, 1033; A., 1934,1114.12 J., 1935, 615; A., 813. F. Haurowitz (ref. 4) has also found thatmetallic derivatives of porphyrins have substantially the same dimensionsas the parent substances.13 J.M. Robertson, R. P. Linstead, and C . E. Dent, Nature, 1935, 134,506; A., 689; cf. R. P. Linsteadand A. R. Lowe,J., 1934,1031; A., 1934,1114.14 In the last few months, H. Fischer, H. Haberland, and A. Muller(Annalen, 1936, 521, 122) have described pyrrole derivatives of a new type,called di-iminoporphyrins. These contain four pyrrole rings joined ontwo sides by the ordinary methenes and on the other two sides by (-NH-)or (-N=) groups. These substances to some extent bridge the gap betweenporphyrins and phthalocyanines.1 5 J. B. Conant and J. F. Hyde, J . Arner. Chem. Xoc., 1930, 52, 1233; A.,1930, 799.16 H. Fischer and G. Stangler, Annalsn, 1927, 459, 53; A., 1928, 76.1 7 H.Fischer and W. Neumann, ibid., 1932, 494, 228; A., 1932, 626.18 H. Fischer, M. Speitman, andH. Meth, ibid., 1934,508,154; A., 1934, 308.19 A. Treibs, ibid., 1933, 506, 196; A., 1933, 1309.20 H. Fischer and A. Stern,ibid., 1935,619,58; 520,88; A., 1135, 1383.M 362 ORGANIC CHEMISTRY.The absorption spectra of porphyrins in the visible region areremarkably like the ultra-violet spectrum of benzene.21 Finally,no isomerides are known corresponding with changes in the finestructure; e.g., no porphyrin exists in two forms, one with theimino-hydrogen atoms on adjacent pyrrole rings (as in A), theother with them on diagonally opposite rings. Neither are isomericmetallic derivatives of these forms known (Fischer, Conant, Dietz).The same appears to be true of phthalocyanines.This of coursecorresponds with the fact that! o-disubstituted benzenes do notexist in two forms.Chlorophyll has occupied the attention of chemists for nearly acentury, since Berzelius first attempted to isolate the pigment fromgreen leaves, but it is only in the last thirty years that real progresshas been made. To-day the problem of its constitution is nearlysolved, thanks mainly to the researches of Willstatter and HansFischer and their collaborators. Valuable contributions havealso been made by J. B. Conant, A. Stoll, and L. Marchlewski.Some of the earlier work has already been summarised in theseReports,Z3 but a short critical review of it in the light of the mostrecent developments is now given because the problem and thenomenclature are very complex and the early results have beencorrected in some respects.Chlorophyll occurs in the chloroplasts of green plants, mainlyin the leaves, accompanied by the yellow pigments carotin, xantho-phyll, and (in brown algze) fucoxanthin.G. G. Stokes24 andH. C. Sorby 25 provided the first evidence that chlorophyll is nothomogeneous and this was confirmed by M. Tswett,26 the discovererof the chromatographic method of analysis. At one time it wasthought that a large number of different chlorophylls existed,that of monocotyledons, for example, being different from that ofdicotyledons, but this was disproved by R. Will~tatter,~~ who21 J. B. Conant and S. E. Kamerling, J . Amer.Chem. SOC., 1931, 53, 3522;A., 1931, 1310; see p. 390.22 General accounts are given by R. Willstatter and A. Stoll (“Unter-suchungen uber Chlorophyll,” Berlin, 1913) and by H. Fischer (Oppenheimer’s“ Handbuch der Biochemie,” 1923,351; 1930,87; 1933, 262; J . , 1934, 245),and valuable short reviews by K. F. Armstrong (Chem. and Ind., 1933, 809)and E. M. Dietz ( J . Chem. Educ., 1935, 12, 208).23 Ann. Reports, 1911, 8, 144; 1912, 9, 169; 1913, 10, 151.?‘I Proc. Roy. SOC., 1864, 13, 144; J., 1864, 1’7, 304.Z 5 Proc. Roy. SOC., 1873, 21, 442.2c Ber., 1908, 41, 1352; Ber. deut. bot. Ces., 1906, 24, 316; A., 1908, i,27 R. Willstatt,er and A. Stoll, “ Chlorophyll,” p. 117.440 ; 1906, i, 973. LINSTEAD : TME PORPHYXCIN GROUP. 363showed that chlorophyll from a wide variety of sources is a mixtureof two very similar pigments, the blue-green chlorophyll a and theyellow-green chlorophyll b.The proportion of these forms in landplants is a,bout 3 of a t o 1 of b, but the amount of b is much smallerin brown algz. Dry leaves contain some 0.S70 of mixed chloro-phylls. One recent claim28 for the discovery of a third form ( c )has been disproved,29 but an independent line of evidence, althoughindirect, suggests that chlorophyll a may itself be a mixture of twoi~omerides.~~Chlorophyll is a waxy solid which has not yet been obtainedcrystalline. When green leaves are extracted with alcohol, acrystalline green pigment is produced,31 but this involves a secondarydecomposition, the formation of a chlorophyllide.Chlorophyll isbest isolated by extracting dried green leaves with acetone con-taining 15-20y0 of water; the solution is then diluted with lightpetroleum, and the acetone removed with water.32 About 80% ofthe total chlorophyll can be extracted in this way. Tswett 36separated crude chlorophyll in small amounts into the a and the bcomponent (and the carotenoids) by passing a benzene solutionthrough a column of calcium carbonate or sugar. R. WillstBtterand M. Isler removed the chlorophyll b by extracting the petroleumsolution of the crude pigment with 90% methyl Tswett’smethod has been improved by A. Winteratein and G. Steinf4 andWillstatter’s by A. Stoll and E. Wiedemann.35 Absorption spectraindicate that the older preparations of chlorophyll b containedsome 10% of a.For work on the degradation products it is usual,not to separate the two chlorophylls, but to hydrolyse the mixedpigment to pheophorbide (a + b ) and separate this into its com-ponents by acid fractionation (p. 366).Chlorophyll and closely related substances retain solvents(particularly water) tenaciously and their analysis is difficult.The formule originally given to the two components by Willstatter,36and accepted to-day, are : a, C,6H,205N4Mg ; 6 , C,,H,,06N4Mg.2 8 F. P. Zscheile, Bot. Gaz., 1934, 95, 529; A., 1934, 1115.Z g A. Winterstein and K. Schon, 2. physiol. Chem., 1934, 230, 139; A.,3Q J. B. Conant and E. M. Dietz, Nature, 1933, 131, 131; A., 1933, 287;31 J. Borodin, Bot. Ztg., 1882, 40, 608.32 R.Willstiitter and E. Hug, Annulen, 1910, 318, 21 ; A., 1911, i, 393.33 Ibid., 1912, 390, 269; A., 1912, i, 710.34 2. physiol. Chem., 1933, 220, 263; A,, 1934, 91; compare ref. 29.35 Helv. Chim. Acta, 1933, 16, 739; A., 1933, 838.36 “ Chlorophyll,” p. 144.1935, 362.see p. 388.The analyses for chlorophyll a actually agreedwith the values required for a semihydrate, C6,H,B0,N,Mg,&H,0364 ORGANIC CHEMZSTRY.Earlier workers had believed that chlorophyll contained iron,phosphorus, and other elements. The quantitative basis forthese formula is mainly the analysis of degradation products,particularly the chlorophyllides and phaeophorbides.ChZoro~hyZZi&es.-W~lstatter found that, when chlorophyll ingreen leaves is extracted with ethyl alcohol, a phytyl group (C2oH39)is replaced by ethyl, the reaction being catalysed by an enzyme,chlorophyllase, present in the leaf .37 The bluish-green product(“ crystalline chlorophyll ”) is a mixture of ethyl chlorophyllides(a + b ) , which form mixed crystals.These may be separated bypartition between aqueous methyl alcohol and a mixture of etherand light petroleum. Ethyl chlorophyllide a has the formulaC3,H380,N4Mg and the change in the a series is interpreted byWillstatter as follows :These formulze embody the fact (proved later) that chlorophyll andethyl chlorophyllide contain a carbomethoxy-group. This made theexamination of the structure of ethyl chlorophyllide dScult,because Zeisel determinations yielded a mixture of methyl andethyl iodides.Methyl chlorophyllide u (111, R = CH3) can bemade similarly, and a free chlorophyllide a (111, R = H) by hydro-lysing leaf chlorophyll with acetone containing 33% of water andseparating the a and the b component by partition.38CO OGH, CHMe<[ CH,],*CMe:CH *CH2-OHC32H300N4Mg<C0.0R [CH2]3*CHMefCH2]3*CHMe,(111.) VV.1I n the chlorophyllase reaction the phytyl group is liberated asphytyl alcohol (IV), the structure of which has been determined byF. Gottwalt Fischer and K. Lo~enberg,~~ who synthesised it from+-ionone. It contains four isoprene units. The chlorophyllfrom about 200 different plants yields the same phytol in some30% ~ield.~O’ The phytyl group is responsible for the wax-likeproperties of chlorophyll and its power of forming colloidalsolutions.37 R.WillstBtter and M. Utzinger, Annalen, 1911, 382, 129; A., 1921,38 R. WillstBtter, “ Chlorophyll,” p. 216.39 Ann. Reports, 1929, 26, 220.40 R. Willstlitter, F. Hocheder, and E. Hug, Annalen, 1909, 371, 1; A.,i, 659.1910, ii, 150LINSTEAD : THE PORPHYRIN GROUP. 365Phceophorbi&es.-In 1907, R. Willsttitter and 3’. Hochedersucceeded in removing the magnesium from chlorophyll and thechlorophyllides without secondary decomposition. The olive-brown solids obtained were called phaeophorbides. Leaf chloro-phyll on treatment with hydrated oxalic acid in alcohol yieldedphytyl phaeophorbide or phsophytin (V),* and methyl chloro-phyUide on treatment with 17% hydrochloric acid in ether wasconverted into methyl phEophorbide (VI).The action of strongeracid hydrolysed the phytyl group from phaeophytin and one methylgroup from methyl chlorophyllide to yield phsophorbide (VII),which contained a free carboxy-group. Methyl phaophorbidecould be obtained by hydrolysis of phzophytin with methyl-alcoholic hydrogen chloride.C02Me oxalic acidMeOH,enzymecx2H300N4Mg<(J0. O.C,,~,, -These substances were obtained as mixtures of a and b compoundswhich could be separated by partition between ether and hydro-chloric acid. The separation of phEophorbide a and b is veryimportant in practice, as it is more easily carried out than that of themagnesium- containing compounds.These reactions reveal a considerable difference in ease of hydro-lysis of the two ester groups.Esters of the carboxy-group whichcarries the phytyl group in chlorophyll are readily hydrolysed,whereas the original carbomethoxy-group present in the naturalpigments remains intact.Although the phytol-free compounds can easily be obtainedcrystalline, the determination of their molecular formulae hasgiven some difficulty. The formulae shown above all contain5 atoms of oxygen, following Willstatter. When the study ofchlorophyll was renewed by H. E’ischer and J. B. Conant, bothinvestigators at first preferred formula containing 6 atoms ofa1 AnnaEen, 1907, 354, 205; d., 1907, i, 959; “Chlorophyll,” Chap.* The fornuke (V-VII) are for the CG series.xv366 ORGANIC CHEMISTRY.oxygen.42 In 1932, however, A. Stoll and E.Wiedemann reaffirmedthe 0, formulae43 and these were also adopted independently byboth the other schools.44Acid Xeparation (Willstiitter) .45-Similar substances of thechlorophyll or of the porphyrin series are separated by means oftheir difference in basicity, an ethereal solution of the materialbeing extracted successively with hydrochloric acid of increasingstrength. This procedure cannot be used with compounds con-taining labile metals, such as chlorophyll itself, unless the eliminationof metal is immaterial. The acid number of a substance is definedas the percentage concentration of hydrochloric acid which extractstwo-thirds of it from an equal volume of an ethereal solution :methyl phEophorbide a has an acid number of 16 and is completelyextracted by 18% acid, whereas methyl phaeophorbide b, with anacid number of 21, requires 23% acid for complete removal.Extraction of an ethereal solution of methyl phaeophorbide a + bwith 17% acid therefore leads to almost complete separation.Solutions of the sodium phosphates also are used for suchseparations.Chlorin e.-Willstafter found that, when either phzeophytin orphzophorbide is hydrolysed by boiling methyl-alcoholic causticpotash for 30 seconds, phytochlorin e (a series) and phytorhodin g( b series) are formed.46 These can be separated by acid fraction-ation or the individual substances can be prepared from theseparated phzeophorbides.From this point it is convenient to concentrate on the compoundsof the a series.These have received much fuller study because theyare more accessible and crystallise better.The conversion of phzophorbide a into chlorin e (VIII) involvesthe hydrolysis of the stable methyl ester group and the addition ofit molecule of water :42 H.Fischer and R. Biiumler, Annalen, 1929, 474, 69; A., 1929, 1185;J. B. Conant and J. F. Hyde, J . Amer. Chem. SOC., 1929,51, 3668; A., 1930,225.43 On the occasion of the celebration of Willstiitter’s 60th birthday; Natur-wiss., 1932, 20, 628. The analytical figures were published later (Helv. Chim.A&, 1933, 18, 202, 739; A., 1933, 287, 838).44 H. Fischer and H. Siebel, Annalen, 1932, 499, 84; A., 1932, 1263;compare H. Fischer, 0. Moldenhauer, and 0. Sus, ibid., 1931, 486, 158; A . ,1931, 744; J.B. Conant and C. F. Bailey, J . Amer. Chem. SOC., 1933, 55,797; J. B. Conant and E. M. Dietz, ibid., p. 839; A., 1933, 1403.45 “ Chlorophyll,” p. 262.46 These substances are now generally called chlorin e and rhodin g re-spectively. The suffixes date from the time when series of chlorins andrhodins (of doubtful homogeneity) were obtained by acid fractionation.Only chlorin e need be considered hereLINSTEAD : THE PORPHYRIN UROUP. 3672H,O 40,H-3 C,lHBN,@O,H + MeOHC0,H(VIII.)Chlorin e is a tribasic acid and yields the same characteristic tri-methyl ester by the action of methyl sulphate on the potassiumsalt4' and by treatment with dia~omethane.~~ This shows thatthe fifth oxygen atom in phzophorbide is part of a +acidic group.Willstatter interpreted the reaction as the opening of a lactam ring,a suggestion later adopted by J.B. Conant and E. M. diet^,^^whereas Fischer regards it as the fission of a cyclic P-ketonic ester.These suggestions will be considered later.The three carboxy-groups of chlorin e are dissimilar, and twomonomethyl and two dimethyl esters have been obtained bypartial esterification of the free acid and partial hydrolysis ofthe trimethyl ester.50 Fischer has recently found that phaeo-phorbide and methyl phaeophorbide both yield the trimethyl esterof chlorin e on standing with diazomethane in methyl alcohol.51This remarkable reaction involves a methanolysis catalysed by thediazomethane ; when ethyl alcohol is used as solvent, the +acidicoxygen emerges as a carbethoxy-group.Chlorin e and rhodin g are only obtained by the allraline hydro-lysis of phaeobhorbides under conditions which prevent (or delay)atmospheric oxidation (see p.385). In the presence of oxygenthese and other derivatives of chlorophyll undergo the " phasetest." This is a colour reaction which occurs when an etherealsolution of chlorophyll, a phorbide, a phyllide, or chlorin e (tri-ester)is shaken with methyl-alcoholic potash. The colour changes toa bright yellow-brown and then back to green (Molisch). Chloro-phyll derivatives which show this change are said to be phase-positive.A reaction analogous to the formation of chlorin e is observedwith chlorophyll itself. Hot potash under suitable conditions con-verts this into isochlorophyllins as tripotassium salts.The phytyl47 R. Willsthtter and M. Utzinger, A?malen, 1911, 382, 171; A., 1911, i,659; compare H. Fischer and 0. Moldenliauer, ibid., 1930, 478, 54; A . , 1930,482.48 A. Treibs and E. Wiedemann, ibid., 1928, 466, 264; 1929, 471, 146;A., 1928, 1383; 1929, 941.49 J . Amer. Chern. SOC., 1933, 55, 839; A., 1933, 403.50 H. Fischer and H. Siebel, Annalen, 1932, 499, 84; A . , 1932, 1263; J. B.Conant and K. F. Armstrong, J . Amer. Chem. SOC., 1933, 55, 829; A . , 1933,403.61 H. Fischer, W. Gottschaldt, and G. Klebs, Annalen, 1932, 498, 194;A., 1932, 1263; H. Fischer and J. Riedmair, ibid., 1933, 506, 107; A., 1933,1308368 ORGANIC CHEMISTRY,and methyl groups me hydrolysed and the #-acidic group fixes thethird potassium atom.The magnesium is not affected. iso-Chlorophyllin a (IX) yields chlorin e on treatment with acids.Vigorous Degradation by AZkaZi.-The conversion of chlorophyllderivatives into porphyrins by the action of alkali at high ternper-atures was first achieved by E. H~ppe-Seyler,~~ E. S ~ h u n c k , ~ ~ andE. Schunck and L. Mar~hlewski.~~ Willstiitter and his collabor-ators 56 found that the action of methyl-alcoholic potash and pyridineon isochlorophyllins under pressure at 140-190" led to gradeddecarboxylation and the formation of a series of magnesium-containing phyllins. These could be separated through theirpotassium or ammonium salts. Acid eliminated the magnesiumfrom the phyllins with the formation of the corresponding porphyrins(H, for Mg).The third carboxy-group could not be eliminatedin this way and the final product was phyllophyllin,C3,H,N4MgG0,H , the porphyrin corresponding to which (phyllo-porphyrin) had already been isolated by the 'earlier workers.53* 55The alkaline degradation of the corresponding magnesium-freecompounds, particularly of chlorin e, yielded a series of porphyrinswhich could be separated by the Willstktter method.57* 58* 59 Thereis some difference between the results of the various schoolsregarding the intermediate substances isolated in this reaction, butgeneral agreement on the main final products. These are threeporphyrins of known constitution : two are monocarboxylic acids,phylloporphyrin, C3,H3,N,*C02H (already mentioned), and pyrro-porphyrin, C30H33N,*C0,H, and one a dicarboxylic acid, rhodo-porphyrin, C,oH3,N4(C02H)2.It was first thought that the twomonocarboxylic acids were isomeric, but it is now known thatphylloporphyrin is a methyl pyrroporphyrin. Rhodoporphyrin isa carboxypyrroporphyrin and can readily be decmboxylated to62 Probable constitution; cf. " Chlorophyll," Chap. XVIII.53 Z.physio1. Chern., 1879, 3, 339; 1880, 4, 193; A., 1880, 53, 894.54 Proc. Roy. SOC., 1891, 50, 302.55 Ibid., 1895, 57, 314; Annalen, 1894, 284, 81; A., 1894, i, 341; 1895,i, 296.5~3 R. WillstSitter and A. Pfannenstiel, ibid., 1907, 358, 205; R. Willstiitterand H. Fritzsche, ibid., 1909, 371, 33; A., 1908, i, 198; 1910, i, 126. Will-stiltter also studied the corresponding degradations of allomerised chlorophyll.57 R.Willsthtter, " Chlorophyll," p. 353.68 H. Fischer and A. Treibs, Annalen, 1928, 466, 188; A., 1928, 1382.5@ A. Treibs and E. Wiedemann, ibid., p. 264; A., 1928, 1383LINSTEAD : THE PORPHYRIN GROUP. 369pyrroporphyrin. Phylloporph_yrin can be converted into pyrro-porphyrin by drastic treatment with alkali.The last carboxy-group in pyrro- and phyllo-porphyrins (andin the corresponding phyllins) is very stable. Decarboxylationis best effected by dry distillation with soda-lime 56# 6o or by pyrolysisof the free acids alone or in high-boiling solvents.68 I n this waythe oxygen-free parent substances of the group are obtained ;phylloporphyrin yields phylloetioporphyrin, C,,H,,N,, and pyrro-porphyrin yields pyrroaetioporphyrin, C,,H,4N,.Phylloaetiopor-phyrin is degraded to pyrroztioporphyrin by sodium ethoxide ata high temperat~re.~~ The corresponding magnesium compound,(pyrro)ztiophyllin, has been obtained by decarboxylating rhodo-phyllin . 61-+ Phylloporphyrin --% Phyllozetioporphyrin (- clod - a0alkali I (-cE,> NaOEt (- CHJI-- Chlorin eI(- CO,) - GO, + Rhodoporphyrin -3 Pyrroporphyrin -+ PyrroetioporphyrinIt was a t first thought that the a?tioporphyrins from chloro-phyll were identical with that derived from tho blood pigment(mesoaetioporphyrin). This has been shown to be incorrect byHans Fischer. Nevertheless these chlorophyll porphyrins resemblethe porphyrins of the hzemin series in general properties andare red, crystalline solids with low acid numbers.They aresimply inter-related, but the reaction by which they are formedfrom chlorin e is comparatively complex, as will be seen later.We have now left the exact chlorophyll type, but are approachingsubstances of known constitution.Degradation to PyrroZes.-The drastic oxidation of intact chloro-phyll has given no useful results, probably on account of compli-cations arising from the presence of the phytyl group. FollowingW. Kiister’s classical work on the oxidation of hemin,62 L.Marchlewski oxidised phylloporphyrin with chromic acid to thenitrogen-free anhydride, C,H,O,, corresponding to hematic acid(X, 0 for NH).63 R. Willstatter and Y. Asahina64 found thatrhodo-, phyllo-, and pyrro-porphyrins and chlorin e gave the samemixture of methylethylmaleinimide (XI) and hzmatic acid (X)60 R.Willstatter and Max Fischer, 2. pkysiol. Chem., 1913, 87, 430; A , ,1913, i, 1251.6 1 Idem, Annalen, 1913, 400, 182; A., 1913, i, 1218.62 2. p?qsiol. Chetn., 1899, 28, 1, etc.; A., 1900, i, 68.I33 J . p r . Chem., 1902, [ii], 65, 161; A., 1902, i, 387.6.1 Annalen, 2910, 373, 227; A . , 1910, i, 499370 ORU ANIC CHEMISTRY.when oxidised by chromic acid, Caro’s acid, or lead peroxide.structures of these were already known.TheNH NH: NH NH NHCOACO C O A C O M e A /\Me M e 0 , N eMe!==dEt MeLl*qH, M e l u l E t Me!--!!Et Me-EtCH2*C02H(XI.) (X.) (XII.) (XIII.) (XIV.)One molecule of the chlorophyll derivative yielded rather lessthan one molecule of the acid (X) but considerably more thanone molecule of the imide (XI).Following preliminary work by M. Nencki and L.Mar~hlewski,~~R. Willstatter and Y. Asahina reduced phylloporphyrin with hydro-gen iodide and acetic acid under drastic conditions to hzmopyrrole(XII), kryptopyrrole (XIII), and phyllopyrrole (XIV).66 Ethylchlorophyllide was reduced similarly to it mixture of dimethylethyl-pyrroles, and chlorin e to crude hzemopyrrole and phyllopyrrole.The yields in all these degradations were noticeably worse than thoseencountered in the hEmin series. It was subsequently observedby H. Fischer, A. Merka, and E. Plotz that chlorophyll, unlikehzemin, gave on reduction with hydriodic acid about one molecularproportion of carbon dioxide, corresponding to the presence of alabile carboxyl group.The general conclusions from these results are that at leastthree pyrrole rings are present in the molecule of chlorophyll andits derivatives, that one pyrrole carries a methyl group and a propionicacid group in the P-position, that two pyrroles carry methyl andethyl groups in the @-position, and that the pyrrole rings are joinedthrough carbon atoms (such as methene groups) in the a-position.Structure of Rhodo-, Phyllo-, and Pyrro-porphyrins.-We nowturn to Fischer’s brilliant synthetic work in the field.The existenceof four stable nitrogen atoms in the molecule and the drastic degrad-ation to pyrroles suggested that phylloporphyrin and its associatesbelonged to the porphyrin series. Moreover, the absorptionspectrum of pyrroporphyrin, and to a less extent of phylloporphyrin,was close to that of the porphyrins of the blood series, such asmesoporphyrin.If the parent stioporphyrin of the chlorophyllseries were identical or isomeric with that of the hzmin series,it seemed possible that pyrroporphyrin (and phylloporphyrin,which was then thought to be isomeric with it) might be a simplemonocarboxylated derivative, namely, a tetramethyltriethylporphin-6 5 Ber., 1901, 34, 1687; A., 1901, i, 554.6 6 Annalen, 1911, 385, 188; A., 1912, i, 41.6 7 irbid., 1930, 478, 283; A., 1930, 620LINSTEAD : THE PORPHYRIN GROUP. 37 1propionic acid 68 such as (XV). (It is true that this would meanthat pyrroporphyrin would contain 33 instead of 31 carbon atoms,but analysis could not decide definitely on this point.) The eightpossible isomeric acids of this type were synthesised by Fischerand his co-workers 69p70 and characterised by the melting points oftheir methyl esters and in other ways.None was identical witheither pyrro- or phyllo-porphyrin.Et Me(XV.) Me/' 'Et (p = CH2*CH2*C0,H here and subsequently.)Me\ /MeP EtAt about the same time it was found by A. Treibs and E. Wiede-mann 59 that pyrroporphyrin could be brominated to a mono-bromo-compound which yielded bromocitraconimide on oxidation.Hence pyrroporphyrin contained at least one ring of the typeN<'*TH and was probably a tetramethyldiethylporphinpropionicCCMeacid. It was possible to test this by subjecting the free methenegroup to a series of reactions resembling that used in the synthesisof h ~ m i n , ~ l namely, R-H __p1 R*COMe -+ R*CH(OH)Me ->R*CH:CH, I_, R*Et (where R = tetramethyldiethylporphin-propionic acid, less H).By this process pyrroporphyrin wasconverted into one of the tetramethyltriethylporphinpropionicacids already synthesised. The acid actually obtained 70 (methyl6* The methene groups and pyrrole rings of porphin are numbered andlettered as shown in (XVI). The placing of the hydrogens on the nitrogenatoms, and the consequent position of the double bonds, is arbitrary. Forthe purpose of indicating the position of substituents, the formula is mostconveniently abbreviated t o (XVIa), where the lines represent the #?B-sidesof the four pyrrole rings.669 H.Fischer, H. Grosselfinger, and G. Stangler, Anlzalen, 1928, 461, 221 ;70 H. Fischer, H. K. Weichmann, and K. Zeile, ibid., 1929, 475, 241; A.,7 1 See Ann. Reports, 1932, 29, 209.A , , 1928, 651.1929, 1465372 ORUANIC CHEMISTRY.ester, m. p. 271") was identical with the synthetic acid of formula(XV), in which the orientation of the groups followed from themethod of synthesis. This a t once proved that pyrroporphyrinwas a tetramethyldiethylporphinpropionic acid. It was uncertainwhich of the ethyl groups of the triethyl compound had beenintroduced by the acetylation and subsequent treatment and whichwere the two already present in the pyrroporphyrin. The fkeemethene group of the latter could, however, only be at C,, C,, or C,.Ashas been stated, this substance contains two carboxy-groups,one of which is easily removed with the formation of pyrroporphyrin.It was known from work in the hamin series that a-carboxylicacids of the porphyrin series (e.g., the large class which containsthe carboxy-group at the end of a nuclear ethyl group, as--CH,*CH,*CO,H) are only decarboxylated with great difiiculty.As the labile carboxy-group of rhodoporphyrin was not substitutedin an alkyl group, it was presumably nuclear, being placed on thefree methene group of pyrroporphyrin.Rhodoporphyrin wastherefore either (XVII), (XVIII), or (XIX).This was settled by an examination of rhodoporphyrin.Et Me Et Me C0,H Me Et EtM/ \Et Me/ \CO,H Me/ \Et Me/ \MeP\ /C02HMe MeFX.1'p IdMe MeMe\ /Me /Me(XIX.)P CO2H P Et(XVII.) (XVIII.)It was known from the study of natural and synthetic uroporphyrinsthat the absorption spectra of compounds with adjacent carboxy-groups differed slightly from those in which the carboxy-groupswere separated by allryls.Comparison of the spectrum of" natural " rhodoporphyrin with that of a synthetic isomeride (XX)showed the same difference and indicated that in rhodoporphyrinthe nuclear carboxyl was on C,, next to the propionic acid group.72Synthetic 1 : 3 : 5 : $-tetra-met hyl-2 : 4 -diethyl-6 - carboxyporphin -7 -propionic (XXI ;A = CO,H, B = CH2*CH,-C02H) was identical with rhodopor-phyrin. The corresponding compound without the 6-carboxy-group (XXI; A = H, B = CH2*C€€,*C0,H) was also synthesised,and proved to be identical with pyrr~porphyrin.~~ It followed thatthe completely decarboxylated pyrroetioporphyrin was 1 : 3 : 5 : 8-This was confirmed by synthesis.acid72 H.Fischer and A. Schormiiller, Annalen, 1929, 473, 211; A,, 1929,73 H. Bischer, H. Berg, and A. Schormiiller, ibicl., 1930, 480, 109, 189;1184.482, 232; A., 1930, 931; 1931, 101LTNSTEAD : THE PORPHYXIN GROUP. 373tetramethyl-2 : 4 : 7-triethylporphin (XXI; A = H, B = Et)*This also was proved by synthesis.73Et MeThe very important fact emerges that the parent porphyrinsof the hsmin and chlorophyll series are closely related in structure.74Hemin is the ferric (chloride) derivative of protoporphyrin (XXII).71On reduction the latter gives mesoporphyrin (XXIII), which ondecarboxylation yields aetioporphyrin-I11 (XXIV).This hasexactly the same substituents, except on C,, as pyrroaetioporphyrinand is in fact 6-ethylpyrroaetioporphyrin. This relationship isof considerable biological significance.Cl3,:CH Me Et Me Et Me nne/ \/CH:CH, Me/ \Et Me/ \EtP P P P Et Et(XXII.) (XXIII.) (XXIV.)The simiIarity between the two series suggested the possibility ofinterconversion and this was realised by Fischer in both directions.Pyrroporphyrin was converted into mesoporphyrin, identicalwith that obtained from h ~ e m i n , ~ ~ by a complicated series ofreactions, in which the essential changes on C, were the following :Me, ,Ne Me,, ,Me Me\, 6,M"Mesoporphyrin dimethyl ester has been degraded to a pyrropor-~ h y r i n , ' ~ isomeric with the '' natural " compound, with the C, andC, groups reversed.Phylloporphyrin, which is richer by CH, than pyrroporphyrin,must contain a similar disposition of nuclear substituents, as ityields the latter with sodium ethoxide.The most probable structure7 4 Verdeil's claim (Compt. rend., 1851, 33, 689) that the pigments of theleaf and the blood were related was thus prophetic, although based on invalidexperimental work.75 H. Fiacher and H. J. Riedt, Annulen, 1931, 486, 178; A., 1931, 744.76 H. Fischer and J. Ebersberger, ibid., 1934, 509, 19; A., 1934, 421374 ORGANIC CHEMISTRYwas that having two of the pyrrole rings joined, not by an a-methenegroup as in the simple porphyrins, but by the groupThere are four dissimilar methene bridges (or, p, y , 6 in formulaXVI) in pyrroporphyrin, so four bridge-methyl derivatives arepossible.These were all synthesised; the substance with themethyl group on C,, (XXV) was identical with phylloporphyrinfrom natural sources. 78 It followed that phylloEtioporphyrin hadthe analogous structure with an ethyl group for --CH2*CH2-C02Hon C7.If the structure of the porphyrins be held to be proved bythese syntheses,79 the question arises as to how far we can applythis knowledge to the structure of chlorophyll itself. Willstiitterpointed out the need for caution here, because the vigorous alkalinedegradation may cause some deep-seated change in the molecule.Nevertheless several facts suggest that the relationship is fairlyclose : (i) The same porphyrins and not isomerides are alwaysobtained as final products in the alkaline degradation ; the order ofsubstituents remains the same, and hence it is unlikely that there hasbeen a ring fission and resynthesis.(ii) Some of the reagents whichconvert chlorin e into phylloporphyrin are comparatively mild,e.g., boiling quinoline, phosphoric acid at 140°.80(XXV.)On the hypotheBis of a fairly close structural resemblance, wearrive a t the skeleton (XXVI) for chlorophyll a,81 in which thedouble bonds are neglected. The magnesium atom is placed on twopyrrole nitrogen atoms by analogy with the iron of hzemin and77 A-CH=CH- bridge was also considered by Fischer, but was abandonedin view of the synthetic results.78 H.Fischer and H. Helberger, Annalen, 1930, 480, 235; A., 1930, 932;€1. Fischer, W. Siedel, and L. Le Thierry d'Ennequin, ibid., 1933, 500, 137;A.., 1933, 286.The evidence is strong but not final (see p. 360).R. Willstatter and M. Utzinger, Annalen, 1911, 382, 171; A., 1911, i,This should be compared with the formuke advanced by Fischer, Conant,659.and Stoll (p. 379)LINSTEAD : THE PORPHYRM GROUP. 375because the existence of stiophyllin shows that the metal can becombined independently of oxygen. If to the formula of pyrro-porphyrin the methyl and phytyl groups and the magnesium atomare added and the four hydrogens which these groups replace aresubtracted, a formula is obtained which differs from that of chloro-phyll a (C55H7205N4Mg) by (c303) ’[C31H3402N4 + CH3 + c2(jH3, + Mg - 4H = C52H,202NaMg]’From the formation of phyllo- and rhodo-porphyrins we may placea carbon atom on Cy and an oxygen-carrying carbon atom on C,.If allowance is made for the hydrogen atoms replaced, the unlocatedsubstituents become (CH,O,), which may be presumed t o beattached to the substituents on c6 and C,.Purther, chloro-phyll a contains two carboxy-groups, carrying the phytyl and amethyl group. One of these is located in the propionic acid groupon C, ; the other must presumably form part of the “ 6ysystem.”Actually the structural position is more complicated than is indicatedby this summary, because the fundamental ring system of chloro-phyll, the phorbides, and chlorins differs slightly from that of thederived porphyrins.The next stage in the elucidation of the structure was theestablishing by less drastic reagents of the connection betweenchlorophyll and the porphyrins.A suitable reagent was foundby Pischer 82 in a mixture of hydriodic and acetic acids. At about60” this reduced phaeophorbide a to a leuco-compound, aerialoxidation of which gave it series of phEoporphyrins, which con-tained the same number of carbon atoms as the initial material(34, neglecting the ester group). The exact products formedvaried with the conditions of reaction. Similar treatment ofchlorin e or its trimethyl ester gave another series of C,, and C,,porphyrins, the chloroporphyrins. The most important compoundsof these two series are shown below; the formuh are stripped ofester groups to facilitate comparison.83From phsophorbide a, (C,4H,405N4) :Oxyphsoporphyrin a5, 84 C34H3406N4 \ Isolated as monomethylPhsoporphyrin a5, C3&3,05N4 I esters.82 H.Fischer and R. Biiumler, Annalen, 1929, 474, 65; 1930, 480, 197;A., 1929, 1185; 1930, 932; H. Fischer and 0. Moldenhauer, ibid., 1930,478, 54; H. Fischer, A. Merka, and E. Plotz, ibid., p. 284; A., 1930, 482,620; K. Noack and W. Kiessling, 2. physiol. Chem., 1929, 183, 36; A., 1929,727.83 A useful summary of their formation and properties is given by Fischerin Oppenheimer’s “ Handbuch der Biochemie,” ErgBnzungswerk I, 1933,The corresponding ethoxy-266-2 67.84 Originally called neophaeoporphyrin a,.phseoporphyrin a, was originally called phseoporphyrin a8376 ORGAXJC CHEMZSTRY.Prom chlorin e, (C34H&$,) :Isolated as monomethyl { ester.Chloroporphyrin eG, c34153606N4Ghloroporphyrin e6, C33H3405N4Chloroporphyrin e4, Cs3H3604N4 ) Isolated as free acids.[The suffixes a and e denote the derivation from phaeophorbide aand chlorin e respectively. The numbers which follow denote thenumber of atoms of oxygen in the molecule.]These compounds crystallise well and yield polymethyl esterswhen treated with diazomethane. The two series differ in absorp-tion spectra. It should be noted that the stable methyl ester groupof chlorophyll a persists in three of the compounds named in the list.The most important from the structural point of view is phaeopor-phyrin u5, which is isomeric with phzophorbide a and, like it, is amonomethyl ester, but differs from it in absorption spectrum andother properties.85 It was also formed fromphaeophorbides by catalytic hydrogenation over platinum, followedby aerial oxidation of the leuco-compounds formed.s6 J.B. Conantand J. 3’. Hyde also showed that the near derivatives of chlorophyllcould be converted into porphyrins in this way.87Phzeoporphyrin u5 readily loses its carbomethoxy-group andyields phylloerythrin, C33H3403N4, a substance of great importance,first discovered by L. Marchlewski.88 This may be obtained directfrom chlorophyllide and the phzeophorbides by the prolongedaction of boiling 20% hydrochloric acid and also by the biologicaldegradation of chlorophyll. It has been found in ox-bile, thefaeces of ruminants, elephants and other herbivora, and in cattlegall-~tones.~~ The best source is sheep dung.It is extremelystable and its chemical properties and absorption spectrum show it tobe a porphyrin. The formation of a porphyrin by a simple bio-logical process shows independently that chlorophyll contains abasic structure very like $hat of the porphyrin~.~~The actual process in the digestive tract is one of isomerisation85 H. Fischer and 0. Sus, Annalen, 1930, 482, 225; A., 1931, 102.8 6 H. Fischer and H. Helberger, ibid., 1930, 480, 260; A,, 1930, 932;M. Fisher and E. Lakatos, ibid., 1933, 506, 123; A., 1933, 1308; compareE. M. Dietz and T. H. Werner, J . Amer. Chem. SOC., 1934,56, 2180; A , , 1934,1371.It yields a monoxime.87 Ibid., 1930, 52, 1233; A., 1930, 799.8 8 2.physiol. Chem., 1929, 185, 8; A., 1929, 1468.8@ H. Fischer and R. Hess, ibid., 1930, 18’9, 133; A., 1930, 634.So Early evidence of the close connection between the green derivativesof chlorophyll and the porphyrins comes also from J. B. Conant and J. F.Hyde’s demonstration that porphyrins were produced by the pyrolysis ofchlorin e ( J . Amer. Chem. SOC., 1929, 51, 3668; A., 1930, 225)LINSTEAD : THE PORPHYRIN QROUP. 377and decarboxylation, and appears to be confined to the higheranimals. A number of other degradation products of chlorophyllin vivo have been discovered, e.g., probophorbides (sheep dung)and phyllobombycin (fsces of silk-worms). These contain amodified porphyrin system.The structure of phylloerythrin has been established by Fischerboth analytically 91*92 and by synthesis.One of the oxygen atomsis ketonic; fhe oxime on reduction by the Kishner-Wolff methodgives deoxophylloerythrin ( C33'H3602N4), in which the two remainingoxygens are present as carboxyl. Deoxophylloerythrin can beobtained directly from phaeophorbide a by treatment with hydrogenbromide in acetic acid a t 180". It is not identical with any of theisomeric te tr ame t h yltr ie t h y lporp hinpr opionic acids, which onlydiffer from it in formula by two hydrogen atoms. Phylloerythrinon treatment with sodium ethoxide in presence of air yields phyllo-,pymo-, and rhodo-porphyrins.Fischer's interpretation of these facts, which is generallyaccepted, is that in both phylloerythrin (XXVII) and its deoxo-compound (XXVII, CH2 for CO), the C, and C, carbon atomsform part of a, five-membered carbon ring.Et Me(XXVII.)The presence of this was shown by the synthesis of deoxophyllo-e r ~ t h r i n .~ ~ The relationship between the two substances wasconfirmed by the oxidation of deoxophylloerythrin to phylloerythrinby oleum containing ~u1phu.r.~~ The yield was poor and somechloroporphyrin e5 was formed by further oxidation. The positionof the carbonyl group at C, in phylloerythrin follows from its fissionby alkali into phylloporphyrin and rhodoporphyrin, which recallsthat of deoxybenzoin into benzoic acid and toluene : R*CH,*COR'_I, R*CH3 + HO*OC-R'.1931, 496.81 H.Fischer, 0. Moldenhauer, and 0. Sus, Annalen, 1931, 485, 1 ; A.,O2 Idem, ibi&., 1931, 486, 107; A., 1931, 744.93 H. Fischer and J. Riedmair, ibid., 1931, 490, 91; 1932, 49'7, 181; A,,94 H. Fischer, J. Heckmaier, and J. Riedmair, ibid., 1932, 404, 86; A.,1931, 1431; 1932, 1045.1932,625378 ORGANIC CHEMISTRY.The structure of deoxophylloerythrin has been confirmed by itssynthesis from phyll~porphyrin.~~ The latter was converted intoits hEmin (ferric compound), and a CH,*OMe group introduced on c6 by means of chloromethyl ether and stannic chloride. Theproduct was freed from iron and purified by successive treatmentwith hydrogen bromide and alkali. The oxymethyl porphyrin wasfinally converted into deoxophylloerythrin by fusion with succinicacid, which eliminated methyl alcohol and formed the 9 : 10-bond.Phzoporphyrin a5 (XXVIII) was recognised by Pischer as the@-ketonic ester corresponding to phyll~erythrin,~~ a view acceptedby Conant and Stoll.When hydrolysed with acid or cold alcoholicpotash, it underwent ring fission of the usual cyclopentanonecarb-oxylate type and yielded chloroporphyrin e6, the methyl hydrogenester of the corresponding open-chain (adipic) acid (XXIX) :C0,Me Ph ylloporphyrin(XXVIII.) C0,Me (XXIX). / (XXX.) \(XXXII. )II IIOHCH CO H0,C C0,H--+ yy y-y\/ 0(XXXIIa.) (XXXI.)[These partial formulae show the portion of the molecule below the dottedThe methyl hydrogen ester (XXIX) can be cyclised back to(XXVIII) by rather unusual reagents: pyridine and sodiumcarbonate, or a mixture of hydriodjc and acetic acids.E’ormic acidremoves the carbomethoxy-group from chloroporphyrin e6 to givechloroporphyrin e4 (XXX), which can be further decarboxylatedto phylloporphyrin. Chloroporphyrin e4 is therefore y-methyl-rhodoporphyrin (or phylloporphyriii-6-carboxylic acid) and chloro-porphyrin e6 is the ester of rhodoporphyrin-y-acetic acid. Thepresence of the 6-carboxyl makes the methyl group of y-methyl-rhodoporphyrin very easily oxidisable (contrast phylloporphyrin) ;according to the conditions it yields chloroporphyrin e5 (y-formyl-9 j H. Fischer, M. Speitmann, and H. Meth, Annalen, 1934, 508, 154; A.,1934, 308.line in (XXVII), the rest of the molecule being the same.LMSTEAD : THE PORPHYRM GROUP.379rhodoporphyrin, XXXIP ; which appears to exist normally in thecyclic form XXXIIa) or rhodoporphyrin-y-carboxylic acid (XXXI).The latter is also formed by the action of oxygen and alkali onphylloerythrin. A number of other transformations of theseporphyrins have been studied by Fi~cher.8~~ 9~ 92* 94Fischer’s view that phEophorbide a and phzeoporphyrin cc5(monoester) on the one hand, and chlorin e and chloroporphyrin e6on the other, are pairs of isomerides has not been accepted byJ. B. Conant, who regards the chlorophyll derivatives as beingricher in hydrogen than the porphyrins. This point cannot besettled by analysis, but calorimetric determinations by A. Sternand G. Klebs96 support the idea, of isomerism. In any case, it isCIQH2 C02MeC0,PhytylQH2 C0,MeC 0,Phy t yl(XXXIII.) (XXXIV.)H. Fischer.97 J. B. C ~ n a n t . ~ ~Et CH Me(7H2 TH CH*OHYHz C02MeC0,PhytylA. st011.9996 Annalen, 1933, 505, 295; A., 1933, 1173.97 Ibid., 1933,502, 175; A., 1933,617. Revised from several earlier formuls.98 J. B. Conant and E. M. Dietz, J . Amer. Chem. SOC., 1933, 55, 839; A.,1933, 403. Revised from a, previous formula (ibid., 1931, 53, 2382 ; A., 1931,1075). The y-side chain wits believed to be of the type >C:CH*CO,Me+>CH.CH( OH)*CO,Me.Experimentalresults appeared later (HeZv. Chim. Acta, 1933, 16, 183; A , , 1933, 287, etc.).gg A. Stoll and E. Wiedemann, Natwwiss., 1932, 20, 706380 ORGANIC CHEMISTRY.now clear that chlorophyll and its near derivatives contain a ringsystem similar to but not identical with that of the porphyrins.This is referred to as the isoporphyrin (isoporphin) system.In 1932-1933, the three formulze for chlorophyll on p.379 wereproposed and it is convenient to consider further investigations inrelation to them.These forrnulz have certain common features, based mainly onFischer’s synthetic work, namely, a modified porphin ring, virtuallythe same arrangement of alkyl substituents in the p-positions ofthe pyrrole rings, and carbon substituents on C, and C,,. Thephytyl group is placed on the propionic acid side chain at C,, and themethyl group on the C,, carboxyl, as first proved by C0nant.lPischer proposed the reverse arrangement,92 but later corrected it .2The evidence on this point is briefly as follows : (i) Phzophorbide acontains the original carbomethoxy-group of chlorophyll intactand has one free carboxy-group which originally carried the phytyl.On pyrolysis it yields pyrophzophorbide a (the phorbide corre-sponding to phylloery thrin) with loss of the carbomethoxy-group,but the free carboxyl remains intact.Only a p-propionic acidgroup could survive pyrolysis in this manner. (ii) Ethyl chloro-phyllide also contains the original carbomethoxy-group and hasethyl in place of phytyl. Ilydriodic acid converts it into the ethylester of phzoporphyrin a5, which on pyrolysis yields phylloerythrinethyl ester. Hence the ethyl group in ethyl chlorophyllide andthe phytyl group in chlorophyll arc carried by the propionic acidside chain.Stoll accepted Fischer’s carbocyclic ring, but Conant 98 did notconsider that the presence of this in chlorophyll a or the phgophor-bides was proved by their transformation into phzoporphyrin a5and phylloerythrin.He suggested that the ring might be formedduring the reaction just as it is in the formation of phylloerythrinfrom the chloroporphyrins.All three formulz differ as to the state of reduction of the mole-cule and the mode of combination of the fifth oxygen atom.Fischer placed this in a carbonyl group a t C,, Stoll in a secondaryalcohol group, and Conant in a lactam ring. Early attempts toprepare ketonic derivatives from chlorophyll a and the phorbidesof the a series had failed, though H. Fischer and J.Riedmair hadobtained indirect evidence for the keto-group in the formation oftri-acid derivatives with diazomethane in an atmosphere of nitrogen 31 J. B. Conant and J. F. Hyde, J . Amer. Chem. Soc., 1929, 51, 3668; A.,1930, 225; J . B. Conant, E. M. Dietz, C. 3’. Bailey, and S. E. Kamerling,ibid., 1931, 53, 2382; A., 1931, 1075.H. Fischer, 0. Siis, and G. Klebs, AnnuZen, 1031, 490, 38; A., 1931, 1431.3 Ibid., 1933, 506, 107; A , , 1933, 1308LINSTEAD : THE PORPHYRIN GROUP. 381(which would prevent the oxidation of a secondary alcohol of thetype suggested by Stoll). Apparent support for the alcohol formulacame from A. Stoll and E. Wiedemann’s preparation of a benzoylderivative from phsophorbide a and methyl phzeophorbide a.4The presence of a keto-group was proved independently andconclusively by Fischer 5 and Stoll,6 who prepared a phase-positiveoxime from methyl phzophorbide a.This could be converted intothe oxime of phsophorbide, phzophorbide itself, or the oxime ofphaoporphyrin a5 according to the conditions. This result ledStoll to abandon the alcohol grouping on C, in favour of carbonyl,but he retained the dihydroporphin arrangement of the nucleus.The benzoylation was interpreted as a reaction of the enolic formof the phorbides. The presence of a, keto-group in phEophorbide ais incompatible with Conant’s lactam formula, which is also opento objection on stereochemical grounds.Fischer’s 1933 formula (XXXIII) contained two free imino-groups and three of the methyl groups converted into methylenes(arbitrarily the ones on C,, C,, and C,).Experimental support forthe free imino-groups seemed to be provided by Zerewitinoffdeterminations of active hydrogen, but the method is of doubtfulvalue in this series and in view of subsequent developments theresults probably are not significant. Strong evidence has recentlybeen found by Fischer for the presence of unsaturated side chainsin chlorophyll and the isoporphin derivatives generally, by the“ oxo-reaction ” and the addition of diazoacetic ester.H. Fischer and J . Riedmairs found that when phaophorbideor methyl phaeophorbide was treated with cold hydriodic andacetic acids, best in a steam of oxygen, a crystalline porphyrin,oxophEoporphyrin a5, containing 6 atoms of oxygen, was formed.In nitrogen the reaction gave the usual phsoporphyrin a5.Theoxo-porphyrin yielded a dioxime and hence contained a secondcarbonyl group : the reaction was t’herefore an oxidation in additionto the usual isoporphin --+ porphin change. The oxo-reaction wasalso given by chlorin e, chlorin e4 (formed by decarboxylationof chlorin e in pyridine), and pyrophaophorbide, but not by thederived porphyrins. It was first thought that these oxo-compoundscontained an aldehydo-group in place of an unsaturated sideHelv. Chim. Acta, 1933, 18, 739; A., 1933, 838:H. Fischer, J. Riedmair, and J. Hasenkamp, Annalen, 1934, 508, 224;A. Stoll and E. Wiedemann, Helv. China. Acta, 1934, 17, 163; A., 1934,There was a polemic as t o priority : both the papers cited 6.6 are datedA., 1934, 420.308.December, 1933.7 H.Fischer and P. Rothemund, Ber., 1931, 64, [B], 201; A., 1931, 497.* Annulen, 1933, 505, 87; A., 1933, 959382 ORGANIC CHEMISTRY.hai in,^ but a comparison with synthetic formylporphyrins showedthis to be incorrect. Fischer accordingly abandoned the hypothesisthat chlorophyll a and its near derivatives contained methylenegroups (XXXIII) and considered that the oxoporphyrins weremonoacetyl compounds in which the acetyl group was derivedfrom a single ethylidene group on C, or Cp.9 The position of thissubstituent was found as follows: Under the conditions of theoxo-reaction, pyrophEophorbide a yielded oxophylloerythrin. Whenthis was heated with hydrochloric acid in a sealed tube, the carbonyl-containing side chain was eliminated and two new porphyrins wereformed.These resembled pyrroporphyrin and phylloerythrinrespectively but were not identical with them. The first containedtwo free pyrrole methene groups and was considered to be a de-ethylpyrroporphyrin (such as XXXVI) ; the second, with onefree methene group, was a de-ethylphylloerythrin (such asXXXVII) which could be reduced to the corresponding deoxo-compound, with CH, for CO.(XXXVI.)P(XXXVII.)The structure of these was proved by their synthesis by Fischer’sgeneral methods. 1 : 3 : 5 : S-Tetramethyl-4-ethylporphin-7-prop-ionic acid (XXXVI) gave an ester identical with that of the de-ethyl-pyrroporphyrin from oxophylloerythrin.lO Both the possiblede-ethyldeoxophylloerythrins were synthesised by H.Fischer andW. Rose; the 2-de-ethyl compound (XXXVII; CH, for CO)was identical with that prepared from natural sources.12 It followsthat the oxo-group in the oxoporphyrins, and hence the unsaturatedside chain in the phorbides, is in the 2-position. The nature of theoxo-group was proved as follows. The ester of 2-de-ethylpyrro-porphyrin (XXXVI) was converted into the hamin (ferric) com-pound and acetylated to a diacetyl derivative (CH,*CO for H a tC, and C,). The same compound was formed by the acetylationH. Fischer and J. Hasenkamp, Annalen, 1934, 513, 107; A., 1934, 1370.lo H. Fischer and S. Bockh, ibid., 1935, 516, 177; A., 633.11 Ibid., 1938,519,l; A., 1134.l2 The nomenclature is rather confusing : “ Deoxo ” here implies thereduction of the keto-group at C, ; ‘‘ 0x0 ” in oxophylloerphrin.that an acetylgroup is present instead of ethyl at C,LINSTEAD : THE PORPHYRIN CROUP. 383(at C,) of ox~pyrroporphyrin.~~present at C2 is acetyl.Hence the substituent alreadyThe formula of the oxoporphyrins is typified by (XXXVII1) :(XXXVIII. ) (XXXIX.) (XL.)R = CO,Me, Oxophaoporphyrin a5.R = H, Oxophylloerythrin.The unsaturated side chain which gave rise to the acetyl groupmight be ethylidene or vinyl. This was settled by H. Fischer andH. Medick by use of the diazoacetic ester reaction.14 Protopor-phyrin, the metal-free porphyrin Corresponding t o hamin, is knownto contain two vinyl groups.71 It reacted with diazoacetic ester at100" with elimination of nitrogen to yield the corresponding dicyclo-propane compound (XXXIX) .14 The absorption bands wereshifted towards the blue region and the product no longer reactedwith hydrobromic acid. Oxidation of (XXXIX) with chromic andsulphuric acids gave a mixture of hzematic acid and the cyclopropanemaleinimide (XL).Methyl phaeophorbide u also reacted with diazoacetic ester.The absorption bands were shifted slightly towards the blue region,but without alteration of the characteristic phorbide type.Theproduct on isomerisation with hydriodic and acetic acids gavethe corresponding porphyrin, the analysis of which agreed with theaddition of a >CH*CO,Me group. Pyrophsophorbide gave asimilar compound, which could also be obtained by the pyrolysisof the methylphaeophorbide product.Catalytic reduction andreoxidation of this yielded the porphyrin addition compoundcorresponding to phylloerythrin. Vigorous oxidation of this gavemethylethylmaleinimide and the cyclopropane compound (XL)identical with that obtained from the addition compound of proto-porphyrin. The same substance was obtained in bad yield bythe direct oxidation of the diazoacetic ester adduct of pyrophaeophorbide. Chlorin e trimethyl ester also added diazoacetic ester13 H. Fischer and J. Hasenkamp, Annulen, 1935, 519, 42; A., 1134.1* Ibid., 1936, 517, 245; A., 871384 ORGANIC CHEMTSTRY.The significance of these results is increased by the fact thatporphyrins with saturated side chains such as the haemato- andmeso-porphyrin of the haemin series, and the phaeoporphyrin a5and phylloerythrin of the chlorophyll series, do not react withdiazoacetic ester.The important fact therefore emerges that the nearest derivatives ofchlorophyll contain the vinyl group in the same position as one of thevinyl groups of hcernin and the leaf and blood pigments thereforecome into even closer relationship.The recognition of the unsaturated side chain as a vinyl grouphas the advantage that its conversion into the acetyl group bythe “ oxo-reaction ” can be interpreted simply as follows : l4CHXH, --> \ CHI*CH, 5% CH(OH)*CH, >O*CH,/- /- /-The mechanism which had previously been advanced to explain theforitlation of a carbonyl-containing side chain from an ethylideneor methylene group had been comparatively complicated.A difficulty which remained was that, though the vinyl groupsin haemin add the elements of hydrogen bromide or water readily,this had not been observed in the chlorophyll series.H. Fischerand J. Hasenkamp have, however, found that the vinyl groupsof phzophorbide a add hydrogen bromide under tho conditionswhich convert haemin into haematoporphyrin. The hydrogenbromide adduct is unstable, but its methanolysis products havebeen isolated.The assignment of one double bond in the side chains in placeof the three of the earlier Pischer formula (XXXIII) was in harmonywith the formation and properties of dihydrophaeophorbide. Thishad been prepared by the hydrogenation of phaeophorbide a informic acid with one mole of hydrogen over Adams’s ~ata1yst.l~It is phase-positive and yields an oxime; hence the carbonyl grouphas not been reduced. Preliminary experiments indicated that thisand other dihydro-compounds gave a poor yield of “ oxo-com-pounds.” Re-examination of dihydrophaeophorbide, carefully puri-fied by the chromatographic method, showed that only phaeo-porphyrin a5 and no oxoporphyrin was formed under the conditionsof the oxo-reaction.l3 Hence the dihydro-compound carries anethyl group in place of vinyl at C,.It seems probable that theearly discovery by 5. B. Conant and J. F. Hyde l6 that phaeophor-bide a and chlorin e, but not porphyrins, could be reduced in aqueoussolution by hydrogen over palladised asbestos, can also be explainedas a, reduction of the vinyl group.l6 J .Amer. Chem. SOC., 1930, 52, 233; A., 1930, 799.H. Fischer and E. Lakatos, Annalen, 1933, 506, 123; A., 1933, 1308LMSTEAD : THE PORPHYRIN GROUP. 385These results led Fischer to propose formulae for chlorophyll abased on the following for phaeophorbide a.(XLIa.)CH:CH,I Me$?H COC0,Meor (XLIb.)More recent modifications of these are dealt with later.Allomerisation and the Phase Test.-When an alcoholic solutionof chlorophyll is evaporated to dryness or allowed to stand, it isallomerised and loses its power of crys ta1li~ation.l~ This processwas recognised as an oxidation by J. B. Conant,ls who is responsiblefor much of our knowledge in this field. He showed that theoxidising agent was aerial oxygen and that two equivalents of 0were utilised.lg This was confirmed by H.Fischer,20 who foundthat benzoquinone could bring about a similar change. Anotherdehydrogenating agent is potassium molybdicyanide.21green colourchange brought about in chlorophyll derivatives by the additionof methyl-alcoholic potash (p. 367). This also was shown to involvean oxidation by two equivalents of aerial oxygen.22 As has beenstated, rapid saponification of phaeophorbide a with boiling methyl-alcoholic potash yields chlorin e without oxidation, because thealcohol vapour protects the phorbide from the air. In phase-testsaponification, the hydrolysis is slower and oxidation can proceed.Similar results were obtained by H. Fischer, 0.Sus, and G. Klebs,20who found that the first colour change (green to brown) does notinvolve oxidation, which only occurs during the change back togreen. Some chlorin e is normally formed during phase-test17 R. Willstlitter and M. Utzinger, Annalen, 1911, 382, 129; A., 1911, i,18 J. B. Conant, J. F. Hyde, W. W. Moyer, and E. M. Dietz, J. Amer.19 J. B. Conant, S. E. Kamerling, and C. C. Steele, ibid., p. 1615; A.,20 Annalen, 1931, 490, 84; A., 1931, 1431.21 J. €3. Conant, E. M. Dietz, C. F. Bailey, and S. E. Kamcrling, J. Amer.22 C. C. Steele, ibid., p. 3171; A., 1931, 1169.The “ phase test ” is the green + brown659.Chem. SOC., 1931, 53, 359; A., 1931, 368.1931, 745.Chem,. SOC., 1931, 53, 2382; A., 1931, 1075.Compare ref. 19.REP.-VOL.XXXII. 386 ORQANIC UHE116ISTRY.saponification, but it was found by J. B. Conant and W. W. Moyer 23that this could be entirely prevented if ethyl or, better, n-propylalcohol was used in place of methyl alcohol as a solvent. Thisis due to the ready absorption of oxygen by the solutions of alkaliin the higher alcohols. Allomerised chlorophyll does not show abrown phase, but gives a green solution a t once under phase-testconditions. These results show the correctness of Willstatter’sview that the changes brought about by the phase test and allomer-isation are essentially the same.had shown that the principal product of phase-tes tsaponification of phzeophytin was an unstable chlorin, phytochloring. Conant and Moyer 23 found that the same mixture of unstablechlorins was formed by treatment of the phorbides and of chlorin etri-ester under the conditions of the phase test.On standing inether, these changed into two purplish-brown crystalline solidscalled phaeopurpurin 7 and 18.24 Phaopurpurin 7 was a mono-methyl ester and yielded with diazomethane a trimethyl esterwhich was also formed directly from the unstable chlorins by thesame reagent. When hydrolysed with hot methyl-alcoholic alkali,it lost the group -CO*CO,Me, yielding chlorin f and potassiumoxalate. This indicated that it contained an a-ketonic acid group.Chlorin f 2 5 is a dibasic acid which on treatment with hydrogeniodide and reoxidation yielded rhodoporphyrin, which was alsoformed directly from phzeopurpurin 7 and alcoholic potash a t150°.23 Pyrolysis of chlorin f yielded pyrroporphyrin (see schemebelow).PhEopurpurin 18, which contains one free and two maskedcarboxyl groups, is formed from the unstable chlorins by fissionof carbon dioxide on standing in ether.26 Its hydrolysis yielded achlorin (tri-acid) apparently identical with Willstatter’s chlorin a andcalled chlorin p 6 by Fischer.This regenerated phzeopurpurin 18 onstanding or by the action of heat. When heated alone or in solvents,phEopurpurin 18 yielded the curious green anhydride of rhodo-porphyrin-y-carboxylic acid,27 and with alcoholic potash at 150”23 J . Amer. Chem. SOC., 1930, 52, 3013; A., 1930, 1299.24 These suffixes correspond with the acid numbers of the compounds.(See p.366.)25 Probably identical with Willstatter’s phytochlorin f (“ Chlorophyll,”p. 303), and named rhodochlorin by Fischer.26 E. M. Dietz and W. F. Ross, J. Amer. Chem. SOC., 1934, 56, 159; A.,1934, 308. These authors point out that chlorin a and phEopurpurin 18had been described by H. Malarski and L. Marchlewski in 1912 (Biochem. Z.,42, 219; A., 1912, i, 641) under the names p-phyllotaonin and anhydro-P-phyllo t aon in respec t ively .27 H. Fischer, W. Gottschaldt, and G. Klebs, Annden, 1932, 498, 194;A., 1932, 1263.WillstatteLINSTEAD : TH.E POXPHYRIN GROUP. 387rhodoporphyrin itself.23 From these results, Conant concludedthat both allomerisation and the phase test involve a change fromthe potential phylloporphyrin t o the potential rhodoporphyrinstructure.18Fischer and Conant are in substantial agreement on the structuresof the products of these reactions, though they differ as to thenature of the isoporphin-porphin change and the mechanism ofallomerisation.It will be convenient to neglect the first differencefor the moment and to write P for the main porphin unit of thechlorophyll porphyrins and iso-P for the corresponding unit of thephorbides, chlorins, and purpurins. [On this basis chlorin e(according to Fischer) is iso-PLCH2*C0,H ( y ) and rhodo-porphyrin is P-H ( y )C0,H (6)\CH2*CH,*C02H (7)/CO,H ( 6 )\CH2*CH2*C02H (7) .]Dimethylphzeopurpurin 7 is recognised as the tri-ester of they-glyoxylic acid corresponding to chlorin e, and its transformationsare illustrated below : 28tion methane diazo- /CO,Me ( 6 ) allomeriea-Phorbides -3 Unstable chlorins --+ iso-P--CO*CO,Me ( )phase test \CH2-CH,-C8,Me (7)Dimethyl phEopurpurin 7.A t Ipyrolysis C0,HP-H /H +- ; s o - d H\CH,*CH,*CO,H \CH,*CH,*CO,HPyrroporphyrin.Chlorin f (Rhodochlorin).alkaliat 160°-~Rhodoporphyrin.The reactions of phaeopurpurin 1.8, which contains one carbonatom less than phzeopurpurin 7, are interpreted on p. 388.18* 231 2 6 s 27The purpurins and the chlorins derived from them are here repre-sented as containing the isoporphin structure, and hence, accordingto E’ischer, a vinyl group on C,. This is not fully proved, but issupported by a recent statement 29 that phaeopurpurin 7, rhodo-chlorin, and chlorin p 6 all react with diazoacetic ester.28 Based on the scheme given in ref.18.20 H. Fischer and A. Stern, Annalen, 1935, 520, 88; A., 1383388 ORGANIC CHEMISTRY.The study of phzopurpurin 7 has opened up a new field forinvestigation. When the unstable chlorins prepared by the phasetest or allomerisation are allowed to stand, phaeopurpurin 7 isobtained as a monomethyl ester. The methyl group correspondsto that in phzophorbide a and chlorophyll a. When the compoundis pyrolysed in boiling diphenyl, it yields, not chlorin f, but itsmonomethyl ester,18 i.e., the methyl group is not lost with the10-carboxyl. This suggests that phzopurpurin 7 contains acarbomethoxy- (or similar) group at C, ; the suggestion, however,conflicts with the weight of evidence which places this group inother chlorophyll derivatives at Clo.Conant and Dietz 3o findthat phzopurpurin 7 originates from an isomeric impurity inphaeophorbide. The purest phaeophorbides by the same treatmentyield no phzopurpurin 7, but a monomethyl compound in which thecarbomethoxy-group is at C,, as in the usual formulae. Theseexperiments suggest that the isomeric impurity with the abnormalposition of the carbomethoxy-group corresponds to a second formof chlorophyll a. If this can be substantiated, it opens up interestingpossibilities.on standing, - CO /">o Unstable chlorins ---- -$ iso-P-co\CH,*CH,*CO,H/ ,Phaeopurpurin 18. (7)P > , + P-co /CO&P -33/ p , Hiso-P- C0,H\CH,*CH,*CO,H \CK,*CH,*CO,H \CH,*CH,*CO,HChlorin a (Chlorin p 6).Rhodoporphyrin. Rhodoporphyrin -y-carboxylic acidanhydride.Fischer and his collaborators have made a thorough study ofthe allomerisation of chlorophyll derivatives by benzoquinoneand by iodine, the general conclusion being that oxidation occursat Clo. The following results are some of the most significant.If ethyl chlorophyllide is allomerised with benzoquinone in ethylalcohol, and the product treated with hydrochloric acid in ether,crystalline ethyl 10-ethoxyphaeophorbide is 0btained.~1 Thisyields a dihydro-compound (presumably with reduction of the30 Nature, 1933, 131, 131; J. Amer. Chem. Xoc., 1933, 55, 839; A., 1933,31 H. Fischer and J. Riedmair, Annalen, 1933, 508, 107; A., 1933, 1308;287, 403.cf. H. Fischer, L.Filser, and E. Plotz, ibid., 1932, 495, 1 ; A., 1932, 756LTNSTEAD : THE PORPHYRIN GROUP. 3892-vinyl group) and, when it is fully reduced with hydrogen iodide 31or catalytically 32 and reoxidised, gives ethoxyphaeoporphyrin a5(phaeoporphyrin as). The structure of this was known from thework of H. Fischer and J. He~kmaier,~~ who had obtained it by theoxidation of phaeoporphyrin a5 ((timethyl ester) with iodine inethyl alcohol in the presence of sodium carbonate. On the basisof Fischer's formulae, these results can be summarised by thescheme :d x k E t )*CO,Me/QO (6) allomerisation . isO-P-CH.CO,*Me ( y ) ---+ $80-\(-JH,.CH,.CO,Et (7) (quinone* EtoH) \CH,*CH,*CO,EtEthyl phsophorbide a. 10-E thoxyphaoph orbide.1 I HI reduction,.L reoxidationHI reduction, 1.L reoxidationI,EtOH,NaPCO yo -- 4 ~ c ( ~ E t ) * C O , M e\CH2*CH,*C02€€ \CH2*CH2.C02H/ y o P-CH*CO,MePhsoporphyrin u5.E thovyphsoporphyrin a5.Methyl phaeophorbide a can be oxidised similarly with iodinein the presence of sodium acetate to methyl lo-hydroxyphaeo-p h ~ r b i d e . ~ ~ The acetyl compound of this contains the phorbide(isoporphin) ring structure intact and giws the " oxo-reaction."When the free 10-hydroxy-compound is hydrolysed with causticsoda, the isocyclic ring is broken and unstable chlorins are formed,which with diazomethane yield dimethylphaeopurpurin 7.34Difl'erent mechanisms of allomerisation have been proposed byXischer and by Conant. The former suggested that the first processwas dehydrogenation with the formation of a double bond betweenC, and Cl0, this being followed by the addition of water or alcoh01.3~Conant's view was that allomerisation consisted in the dehydro-genation of a secondary alcohol group at Clo.Further comment isunnecessary in view of the unsettled. state of the subject.According to Fisbher, the brown phase of chlorophyll derivatives,the formation of which does not involve oxidation, is connected10 9 - 7-with the formation of an enol at C, : 36 ?--'(OH)- R. KuhnCOzMe32 H. Fischer, E. Lakatos, and J. Schnsll, Annulen, 1934,509,201 ; A., 1934,33 Ibid., 1934, 588, 250; A., 1934, 420.34 H. Fischer, J. Heckmaier, and T. Scherer, ibid., 1934, 510, 169; A.,1934, 785.35 This has been altered in a recent paper by H.Fischer and A. Stern(ibid., 1935, 519, 63; A., 1134) to explain measurements of optical activity,but it is doubtful if the alteration is necessary.666.36 H. Fischer and H. Siebel, ibid., 1932, 499, 84; A., 1932, 1263has suggested that an enolisation of the 10-carbomethoxy-groupoccurs.37 The lengthening of the conjugated chain so obtainedcauses the red absorption band to move into the infra-red region,causing a lightening of the visible colour (green --+ yellow-brown).Fine Xtructure of ChZorophyZZ a.-Considerable light has beenthrown on this difficult subject by the application of three physicalmethods. It has long been known that porphyrins have multi-banded absorption spectra which may be used for their identification.J. B.Conant and S. E. Kamerling 38 have now found that a t thetemperature of liquid air the porphyrins show a unique spectrum ofnarrow bands in the visible region. The green derivatives ofchlorophyll (phorbides, chlorins) have wider bands in the absorptionspectra and are intermediate between most organic colouringmatters and the porphyrins. The relationship between the visiblespectra of porphyrins and the phorbides (or chlorins) resemblesthat between the ultra-violet spectra of benzene and cyclohexadiene.This suggests strongly that chlorophyll derivatives contain thedihydroporphin ring.Evidence pointing in the same direction has come from a studyof the basicity of the four pyrrole-like rings in phorbides, chlorins,and por~hyrins.~~ Willstatter's method of acid fractionation wasbased on the variation in basicity of chlorophyll derivatives and hehad obtained evidence of the greater basicity of two of the nitrogenatoms by the isolation of dihydrochlorides. Conant and hiscollaborators measured the basicity by potentiometric titrationswith perchloric acid in glacial acetic acid, using a chloranil elec-trode.4O The derivatives of chlorophyll were compared withsubstituted pyrroles of known constitution.The porphyrins werefound to contain two relatively strongly basic groups, presumablyof the pyrrolenine type (XLII), and one very weakly basic groupof the pyrrole (XLIII) or isopyrrole (XLIV) type. The secondweakly basic group could not be detected by the method. Thephorbides contained one relatively strong and one very weak basicgroup and a group intermediate in strength.The chlorins resembledthe phorbides except that the intermediate group was rather morebasic. These facts are compatible with the green chlorophyll37 It. Kuhn, P. J. Drumm, M. Hoffer, and E. F. Moller, Ber., 1932, 65,38 J . Amer. Chem. Soc., 1931, 53, 3522; A., 1931, 1310.39 J. B. Conant, B. F. Chow, and E. M. Dietz, ibid., 1934, 56, 2185; A , ,4" Cf. J. B. Conant) and T. H. Werner, &d., 1930, 52, 449; A., 1931, 40;pi, 1785; A., 1933, 52.1934, 1371.J. B. Conant and B. F. Chow, $bid., 1933,455, 3745; A., 1933, 1121LINSTEAD : THE PORPHYRIN GROUP. 391derivatives containing one pyrrolerrine ring, two pyrrole or iso-pyrrole rings, and a dihydropyrrole nucleus of type (XLV) ,N NH NIE NHA-11 11-(XLII.) (XLIII.) (XLIV. ) (XLV.)It had long been thought that chlorophyll and its derivativeswere optically inactive ; 41 the leuco-compounds showed no activityand the intense colour had prevented an examination of the pig-ments themselves.I n 1933, A. Stoll and E. Wiedemann42 over-came the experimental difficulties and showed that chlorophyll aand b were both lmorotatory with [a];!& = about - 265". Theactivity might have come from the phytyl group, as phytyl alcoholis optically active before di~tillation,~~ but this was shown to beincorrect, since the phytyl- and magnesium-free phorbides of thea and b series also were active.42 Stoll and Wiedemann state thatchlorophylls, methyl phaeophorbides, and phaeophorbides (a and b )all racemise in acetone or methyl-alcoholic solutlion and that oldsamples of crystalline methyl phrffophorbides are inactive.H.Fischer and A. Stern, using white light, have confirmed the opticalactivity but not the ease of racemisation. They state that bothsolutions and solids are optically table.^^^^^ The following sub-stances, inter alia, were found to be active : pyrophaeophorbide a,chlorophyllides, 10-ethoxyphaeophorbide, rhodochlorin, chlorin p 6(tri-ester), and dimethylphaeopurpixrin 7, all being laevorotatoryexcept the last two. The activity survived allomerisation, thephase test, and conversion of the active compounds into theirmetallic derivatives. On the other hand, all the porphyrinsderived from these substances anti those from hzmin (and alsoblood hemin itself) are optically inactive.The only known activeporphyrin is uroporphyrin from mussel-shells, and in this theactive centres are very probably difrerent from those of the chloro-phyll derivatives, being located in succinic acid side chains.45As far as the chlorophyll series is concerned, the activity isundoubtedly associated with the isoporphin structure. The factthat phaeophorbide was not racernised on conversion into pyro-phzophorbide showed that C,, was not the active centre (or not4 1 See, e.g., H. Fischer and H. Siebel, Annalen, 1932, 499, 94; A., 1932,42 Helv. Chim. Acta, 1933, 16, 307; A., 1933, 515.48 R. WillstStter and F. Hccheder, AnnaEen, 1907, 354, 248 ; R. Willstlitter,E. W.Mayer, and E. Huni, ibid., 1911,378, 84; A., 1907, i, 784; 1911, i, 144.44 Ibid., 1935, 519, 58; A., 1134.46 Ibid., 520, 88; A., 1383.1263392 ORCrANIC CHEMISTRY.the only active centre). As this was the only asymmetric carbonatom in Fischer's current formuke (XLIa and b), these becameinvalid. Fischer and Stern first suggested44 that the y-carbonatom carried a hydrogen atom and was an active centre, butabandoned this idea in view of the activity of rhodochlorin (chlorinf),in which this carbon atom must be of the type -CH= or -CH,-.They point out that asymmetric carbon atoms can only appear bythe formation of a dihydroporphin system and that reductionmust occur on one of the pyrrole rings and not a t the methenebridges or by addition of hydrogen to two nitrogen atoms.45 Ofthe various possibilities, Fischer now prefers formula (XLVI) forchlorophyll a.I n this, ring I11 is tentatively selected as the reducedring and hence carbon atoms 5 and 6 as the asymmetric centres.45This formula (or some near modification) 46 can explain all the morerecent facts and is by far the most satisfactory of those in the field.CHICH,I CH Me(XLVI.)4 6 It appaars to the Reporter that a slight modification of (XLVI) in whichthe two extra hydrogens are placed on a (C=N) bond of one of the pyrrolerings (probably ring 111) would accommodate the physical results better. Thepartial formula is shown in (XLVIa), the resL of the molecule being the sameYH-COC0,Meas in (XLVI). Formula (XLVIa) contains an interrupted conjugated chain,iq place of the continuous conjugation of the porphyrins and (XLVI), toaccount for the considerable change in absorption spectrum; and also thedihydropyrrole ring, as suggested by Conant.Apart from C1, it containsonIy one asymmetric carbon atom (starred). The substance (XLVI) cangive rise to two inactive and resolvable (cis- and truns-) forms according t othe arrangement of t'he substituents a t C, and C,. No such isomerides appearto be knownLINSTEAD : THE FOItPHYRIN UROUP. 393The formulz of Conant and Stoll are not very different from theabove with regard to the isoporphin system. If it be accepted thatthe true porphyrins from chlorophyll contain an ethyl group at C,,and the isoporphyrins (phorbides and chlorins) a vinyl group, thenwe can reconcile the view that the porphyrins and isoporphyrins areisomeric and at the same level of reduction (Fischer) with theview, advanced by Conant from the physical results and also heldby Stoll, that the isoporphyrins conhain a dihydroporphin structure.I n this connection it is of interest that Conant 47 was able to dehydro-genate chlorin f to it porphyrin, isorhodoporphyrin (called +verdo-porphyrin by Fischer).This could be converted into rhodopor-phyrin by reduction with hydrogen iodide and reoxidation, also bymineral acids under certain conditions, but not by mild treatment .47,48Rhodoporphyrin is known to carry an ethyl group at C2 and thelatest work shows that chlorin f carries a vinyl group.On thisbasis isorhodoporphyrin also should have a vinyl group at C, andshould contain two hydrogen atoms less than rhodoporphyrin. 5OThis is in keeping with the results of catalytic hydrogenation 49, 48and with other experiments briefly mentioned in Fischer’s recentpaper.45 If this can be confirmed, one of the remaining difficultiesof the subject will disappear and the changes can be representedas follows : 51CH2*C0,H (7)Chlorin f (C3$&04N4).Rhodoporphyrin ( C32H3404N4).4 7 J. B. Conant and C. F. Bailey, J. Amer. Chem. SOC., 1933, 55, 795; R.,48 E. M. Dietz and T. H. Werner, ibid., 1934, 56, 2180; A , , 1934, 1371.49 H. Fischer and E. Lakatos, AnnaZerL, 1933, 506, 123; A., 1933, 1308.50 Comparison of the absorption spectra of these substances, accordingto A.Stern and H. Wenderlein, supports the idea that they are not isomeric(2. physikal. Chern., 1934,170, 337; A., 1935, 10).5 1 Dietz and Werner (ref. 48) summarise the position from the other pointof view (namely, that the true and the iso-porphyrins are isomeric and thatthe nucleus of chlorophyll is a dihydroisoporphyrin), which does not takeinto account the unsaturated side chain at C,.1933, 403.N 394 ORGANIC CHEMISTRY.On this basis the term isoporphyrin ceases to have any specidsignificance, beyond implying a 2-vinyldihydroporphyrin.Partial Synthesis of Chlorophyll a.-The synthesis of phyllo-erythrin by Fischer leaves only four main gaps in the completesynthesis of chlorophyll a. These are (i) the introduction of acarbomethoxy-group, (ii) the conversion of the porphin into theisoporphin system, (iii) the introduction of the phytyl group, and(iv) of the magnesium atom.The last two stages have beenachieved by Pischer.R. WTillstatter and L. Forsen 52 introduced magnesium intophzophytin and other chlorophyll derivatives by the action of theGrignard reagent, a method also used by A. Stoll and E. Wiede-mann.53 Pischer and his collaborators used the product(RO-MgBr) of the decomposition of the Grignard reagent with analcohol, in order to avoid secondary reactions with carboxy- orcarbomethoxy-groups,5* but his latest paper on the subject 55makes it doubtful if any of these processes are satisfactory for thepreparation of phase-positive material.The method finally foundsatisfactory is the interaction of the phorbide with a compound ofthe RO*MgBr type in the presence of pyridine and an excess ofmagnesium. 55 By this process pure phase-positive chlorophyllide acan be prepared from methyl phzophorbide a more readily than bythe chlorophyllase reaction. This confirms the relationship betweenthe two substances.The esterification of the propionic acid group by phytyl alcoholwas achieved by It. WillstBtter and A. Stoll 56 by a biologicalmethod. H. Pischer and W. Schmidt 57 have successfully appliedEinhorn’s method.58 A solution of phzophorbide a in pyridine ontreatment with phytyl alcohol and carbonyl chloride gave phzo-phytin a indistinguishable from the natural product. Whenhydrolysed in the presence of chlorophyllase, it regenerated phEo-phorbide a ; hence there was no replacement of methyl by phytylat Cl0.Other esters of phzophorbide were prepared by this processand the interesting observation was made that the enzymic actionof chlorophyllase is relatively but not absolutely specific; e.g., itcatalysed the hydrolysis of geranyl and cetyl phEeophorbides, butnot that of the methyl and the bornyl ester.5862 Annalen, 1913, 396, 180; A., 1913, i, 499.63 Naturwiss., 1932, 20, 630.64 H. Fischer and M. Diirr, Annalen, 1933, 501, 107; A , , 1933, 515; H.5 5 H. Fischer and G. Spielberger, ibid., 1934, 510, 156; d., 1934, 785.G 6 Ibid., 1911, 380, 148; A., 1911, i, 391.17 Ibid., 1935, 519, 244; A., 1382.68 Ibid., 1898, 301, 95; A., 1898, i, 577,Fischer and J.Riedmair, ibid., 1933, 506, 118; A., 1933, 1308LMSTEAD : THE POXPHYRIN GROUP. 395Phaeoporphyrin a5 has not yet been synthesised 59 and it appearsthat the porphin --+ isoporphin conversion will be difficult.Synthesis from 2-de-ethylporphyrins, followed by introduction ofthe vinyl group, may be necessary.Chlorophyll b.-The study of this compound is not so welladvanced as that of chlorophyll a, and only a brief summary ofprogress will be given here. As has already been stated, chloro-phylls a and b are very similar in general properties, and phyllidesand phorbides of the b series can be prepared by the usual methods.The formula proposed by Willstatter for chlorophyll b(C,,H,,O,N,Mg) is generally accepted. This contains one moreatom of oxygen and two less of hydrogen than that of chlorophyll a.Drastic alkaline degradation of chlorophyll b gives pyrro-, rhodo-,and phyllo-porphyrins, but in worse yield than in the a series; 6ohence the essential arrangement of the substituents is the same.Phzophorbide b on complete reduction with hydrogen iodideyielded hzemopyrrole and hzmopyrrolecarboxylic acid.,1 Will-statter showed that phaeophorbide b is converted by rapid hydrolysiswith hot alkali into rhodin g, which is a tribasic acid containing7 atoms of oxygen and corresponds to chlorin e of the a series.Theextra oxygen atom of the b series was first proved by Conant 62t o be located in a carbonyl group by the preparation of a semi-carbazone from phBophorbide b.This was shown independentlyby 0. Warburg, who converted phzophorbide b into phzoporphyrinb6 (corresponding t o phzoporphin as) by hydrogen iodide, andprepared an oxime from this.63 Fischer and his collaboratorsalso have obtained a monoxime from rhodin g 64 and one fromphsophorbide b.65 The porphyrins obtained by hydrogen iodidedegradation of phaeophorbide b and rhodin g showed reactionsparallel to those of the compounds of the a series; which indicatedthat a carbocyclic ring containing a $-acidic keto-group was alsopresent in phaeophorbide b.", 66 I n 1934, A. Stoll and E. Wiede-59 Cf. H. Fischer and T. Scherer, Annden, 1935, 519, 236; A., 1382.60 Willstiitter, " Chlorophyll," p. 334; cf. A. Treibs and E. Wiedemann,Annalen, 1929, 471, 146; A., 1929, 941.61 H.Fischer, A. Merka, and E. Plotz, ibid., 1930, 478, 299; A., 1030, 620.6% J. B. Conant, E. M. Dietz, and T. H. Werner, J . Arner. Chern. Soc.,1931, 53, 4436; A., 1932, 174.63 Biochern. Z., 1931, 235, 1 ; 1932, 244, 9; A., 1931, 661.64 H. Fischer, F. Broich, S. Breitner, and L. Nussler, AnnaZen, 1932, 498,228; A., 1932, 1263.66 H. Fischer, S. Breitner, A. Henhchel, and L. Niissler, ibd., 1933, 503,1 ; A., 1933, 839; cf. A. Stoll and E. Wiedemann, Helv. Chirn. Acta, 1932,15, 1132; A., 1932, 1265.6 6 H. Fischer, A. Hendschel, and L. Niissler, Annalen, 1933, 506, 83; A.,1933, 1173; H. Fischer and S. Breitner, ibid., 1934, 510,183; 611, 183; A.,1934, 785, 907396 ORQANIC CHEMISTRY.mann prepared a dioxime of methyl phzeophorbide b and thusconclusively proved the presence of two carbonyl groups.The compounds of the b series therefore contain one carbonylgroup in place of a methylene group of the a series.Conant firstplaced the additional carbonyl group as a ketonic bridge (at Cp)and Fischer put it in the propionic acid side chain (at C,). Sub-sequently Pischer showed that it was present as a nuclear aldehydo-group on C,.67 Rhodin g trimethyl ester was degraded t o 3-de-methyldeoxophylloerythrin, the structure of which was proved byThese results are embodied in the formula (XLVII) ofH. Fischer and A. Stern,69 which accommodates the optical activityof chlorophyll b and phzophorbide b discovered by A. Stoll andE. Wiedema~m.~O This is the most recent formula proposed by(XLVII.)I C0,PhytylFischer, but it would presumably now be modified with respect tothe position of the two '' extra " hydrogen atoms so as to come intoline with formula (XLVI) for chlorophyll a.The presence of thevinyl group a t C3 is inferred by analogy, but has not been proved.There now appears to be no justification for the supposition thatchlorophyll a and b are readily interconvertible either in the plantor in the laboratory.71Other Natui4al Porphyrin Derivatives.BacteriochZoro~h.yZZ.-- Some bacteria have the power of assimilat-ing carbon dioxide and recent investigations have shown that theycontain a pigment closely resembling chlorophyll. K. Noack andE. Schneider 72 first isolated the pigment of certain red sulphur orpurpurbacteria of this type.They found that this compound,bacteriochlorophyll, contained magnesium removable by acids to6 7 H. Fischer, A. Hendschel, and L. Nussler, Annalen, 1935,516, 61 ; A., 530.6 8 H. Fischer and W. Rose, ibid., 1935, 519, 1 ; A., 1134.70 Helv. Chim. Acta, 1933, 16, 307; A., 1933, 515.71 A. Stoll and E. Wiedemann, Naturwiss., 1932, 20, 889; A., 1933, 167.72 Ibid., 1933, 21, 836; A . , 1934, 112.Ibid., p. 5 8 ; A., 1134LINSTEAD : THE PORPHYRIN GROUP. 397give a substance resembling phaeophytin. Two carboxyl groupswere found to be present, one esterified by methyl, the other byphytyl or a similar alcoho1,73 and v:Lrious derivatives were prepared.Noack and Schneider considered that two pigments were present, ofwhich the one in larger amount resembled chlorophyll b and contained6 atoms of oxygen in the molecule.H. Pischer and J. Hasenkamp 74investigated the same (or a similar) substance, isolated by H.Gaffron from pure cultures of Thiocystis violacea. They foundthat the predominating pigment belonged to the a series and hadan absorption spectrum of the “0x0 ”-type (see p. 381). Thecrystalline bacterio-methyl phzophorbide a prepared from it gave,on treatment with hydrogen iodide, two porphyrins, one of whichwas identical with oxophzoporphyrin a5 ester. From this resultthe sixth oxygen atom was placed in an acetyl group on C,.Fischer’s formula 75 for bacterio-methyl phaeophorbide a is(XLVIII), but the fine structure would presumably now be modifiedVH, C02MeC02Meto agree with that of the last formula(XLVI). On Fischer’s formulation, thischlorophylls are all structurally derivedparatively simple processes of oxidationgroups and central metal being neglected) :for chlorophyll a itselfsubstance and the twofrom haemin by com-or reduction (the esterSubstituent at7 -----A -___.-- ~Substance. c,. c,. cp C6. c, -H s m i n ............ CHXH, CH, CH:CH, CH,:CH2*CO2H CH,.CH,CO,HBacterio-chloro-Chlorophyll a.. . . . . . . C2H, CO*CH.CO,E *Chlorophyll b.. . . . . . . CHO .. 1, 9 ,9 ,phyll ............ CO-CH, CH3 .. 9 9 Y ,* Cyclised on t o Cy.73 E. Schneider, 2. physiol. Chem., 1934, 226, 221; A., 1934, 1265.74 Annalen, 1935, 515, 148; A., 362.7 5 H. Fischer and J. Hasenkamp, &id., 1935, 519, 42; A., 1134398 ORGANIC CHEMISTRY.Porphyrins in Minerals.-A. Treibs has made an interestingstudy of the occurrence of porphyrins in a number of minerals.In 1934, from the bitumen of an oil shale from the KarwendelMountains, he isolated two porphyrins,76 deoxophylloerythrin(XLIX, R = CO,H), and the decarboxylated compound, deoxo-phylloerythro-ztioporphyrin (XLIX, R = H).CH,R CH2RThe structure of the first was known, that of the latter was provedshortly afterwards by synthesis.77 Porphyrins were next foundin other shales, in petroleums 78% 79 (from Galicia, Trinidad, etc.), inasphalts 78 (Trinidad, Dead Sea, etc.), in phosphorite~,7~ and inmany Mineral waxes appeared to contain very littlep o r ~ h y r i n . ~ ~ The richest sources were Trinidad oil (which con-tained about 0.04% of total porphyrin) and particularly a bituminousmarl from Switzerland (0.4%).79 These quantities are astonish-ingly high when compared with the chlorophyll content of driedleaves (0.8%).The mineral was extracted successively with acetic acid andchloroform, and the extract treated at 50" with hydrobromic andacetic acids.76 The porphyrins were finally purified by acidfractionation. Besides the two compounds mentioned above,which are derivatives of chlorophyll, Treibs has identified meso-ztioporphyrin (L, R = K) and mesoporphyrin (L, R = C0,H) of thehamin series.78 Coproporphyrin was detected in Thechlorophyll porphyrins are always present in greater amount thanthose from hzmin, and the decarboxylated compounds predominateover the free acids. The deoxophylloerythrin and the derivedztioporphyrin from the Swiss marl occur naturally combinedwith vanadium in the centre of the large ring, as compounds of76 Annalen, 1934, 509, 103; A., 1934, 387.7 7 H. Fischer and H. J. Hofmann, ibid., 1935, 517, 274; A., 871.78 A. Treibs, ibid., 1934, 510, 42; A., 1934, 629.'9 Idem, ibid., 1935, 517, 172; A., 727.Idem, ibid., 1935,520,144; A., 1347LTNSTEAD : THE PORPHYRIN GROUP. 399the type >VO, >VO, or >V(OH),.7g It appears probable that thevanadium enters the complex as a result of a secondary reaction.A stable ferrous complex also has been detected.79 There can belittle doubt that chlorophyll and h%min are the parent substancesfrom which these porphyrins are formed by geological processes.The purity of the products makes it unlikely that there has beenring opening and resynthesis. The production of vanadyl deoxo-p hy lloerythr o - ze t iop orp h yrin from c hloroph y 11 a involves the st ages :(i) replacement of magnesium by vanadium, (ii) elimination of thelabile carbomethoxy-group at Clo ; (iii) conversion into the porphyrinsystem, and (iv) decarboxylation a t C,. The decomposition ofphaophytin to deoxophylloerythro-:etioporphyrin in petroleum at360" has been reproduced artificially.A number of interesting deductions have been drawn by Treibs.The results prove that plants play a major part in the formationof petroleum. The r81e of animals appears less important. Thedecompositions which they undergo must be comparatively mild ;this agrees with the discovery of optical activity, and recently ofcestrogenic properties, in petroleums. Moreover the two carb-oxylated porphyrins, mentioned above, act as recorders of themaximum temperature to which the oil has been subjected, fordirect experiment shows that mesoporphyrin is decarboxylated bya week's heating at 240". Treibs estimates that oils or mineralscontaining acid porphyrins cannot have been subjected t o a tem-perature of more than 200" a t any stage during their formation.It has been necessary to omit a great deal of interesting materialin compiling this Report on the porphyrin field. As usual, themore complete topics have been discussed.R. P. L.E. H. YARMER.E. L. HIRST.R. P. LIXSTEAD.S. PEAT.E. E. TURNER.I?. 8. SPRING

ISSN:0365-6217    

DOI:10.1039/AR9353200243

出版商:RSC    

年代:1935

数据来源: RSC

摘要:

BIOCHEMISTRYTHE year has seen steady progress in many directions, and it is amatter for regret that limitations of space forbid mention of morethan a relatively small number of the advances which have beenmade. Selection has not been easy ; the inclusion of certain subjectswas obvious, but in other cases the choice between inclusion andomission was necessarily decided rather by the personal interestsof the Reporter than by the relative importance of the subjects,which could not readily be distinguished. Even in the subjectschosen for review, much interesting and meritorious work hasperforce received no direct reference.Among the vitamins, B, has come into prominence since thepublication, a t the beginning of the year, of its probable structure ;the presence of a pyrimidine derivative in the molecule, togetherwith a number of scattered references to the occurrence and im-portance of pyrimidines, suggests that in the near future we mayexpect a great increase in the number of publications dealing withthese substances.Flavin chemistry has received a good deal ofattention, and it seems that the structure of lactoflavin is settled,though that of its phosphoric ester, the prosthetic group of theWarburg and Christian yellow enzyme, is still a matter for researchwith respect to the position of the ester linkage. It seems probablethat calciferol, which is no longer alone as an artificial anti-rachiticsubstance, is not identical with the vitamin D present in fish-liveroils. Since vitamin E is now known to be an alcohol, we mayconfidently expect its complete isolation very soon.The male sex-hormone now resembles oestrone in that itscharacteristic activity is exhibited by a number of related com-pounds ; although the most active of them, testosterone, is regardedas the true hormone, one wonders whether that is a final verdict.The corpus luteum hormone, whose structure bears a remarkableresemblance to that of testosterone, still appears to be specific.The process of the conversion of carbohydrate into lactic acidin muscle (or alcohol in yeast) is emerging as a, series of reactionsin which, at two important points, phosphate is received from ortransferred to the nucleotide co-enzyme of the system.Phospho-creatine is not essential to the system, but appears to be intimatelyconnected with it in muscle, in a manner not yet clear.The synthesis of glutathione is an important achievement in thSTEWaRT AND STEWART.401field of organic biochemistry and finally settles the constitution ofthis substance, whose functions in the living cell are graduallybeing elucidated.In the field of intermediate metabolism the most importantadvance of the year is undoubtedly the demonstration that thetheory of P-oxidation is unable to explain the known facts concerningthe oxidation of fatty acids.Chemotherapy is advancing in many directions, and the exampleschosen are merely illustrative of the way in which synthetic sub-stances may supplement or replace naturally occurring drugs andof the applications of biochemistry in determining the mode ofaction of drugs or even of initiating a new form of therapeutictreatment.In the plant biochemistry section considerable space has againbeen devoted this year to growth-regulating substances. Therapid extension of our knowledge in this field seems to demand acontinuation of the Report of last year, in conjunction with whichthe following section should be read.The nature of frost resistancein plants has assumed academic as well as practical importance, andin view of the fact that no reference has been made to this subjectin these Reports for some years a review of the present position isincluded. The section relating to the biochemistry of mouldscovers the past two years.1. ANIMAL BIOCHEMISTRY.Vitamins.Vitamin B, (Aneurin).l-It is now generally admitted that thevarious crystalline preparations of vitamin B, hydrochloride aresubstantially identical and that the substance has the empiricalformula C,,H1,ON,C1,S.As a result of a series of investigationsby R. R. Williams and his co-workers considerable progress hasbeen made in the elucidation of the structure of the vitamin. Whenthe hydrochloride is kept at room temperature in contact with asolution of sodium sulphite containing sufficient excess of sulphurousacid to bring it to pH 4-5, it undergoes fission, giving two products,C,H,ONS (A) and C,H,03N3S (B), in 97% yield.2 The product Ais an oily base, giving crystalline salts ; it contains a hydroxyl groupand on oxidation with nitric acid yields an acid, C,H,O,NS, identicalwith that previously obtained by A.Windaus, R. Tschesche, and1 B. C. P. Jansen, Nature, 1935, 136, 259.2 R. R. Williams, J . Amer. Chem. Soc., 1935, 57, 229; A., 504; R. R.Williams, R. E. Watermann, J. C. Keresztesy, and $1. R. Buchman, ibicl.,p. 536; A., 668402 BIOCREMISTRY.R. Grewe 3 by direct oxidation of the vitamin.* This acid has beenidentified as 4-methylthiazole-5-carboxylic acidY5* and the basicproduct of the sulphite cleavage has been proved by synthesis to be4-methyl-5-(3-hydroxyethylthiazole (I) .5 To product B-the acidicproduct of the sulphite cleavage-is provisionally allocated thestructure (II).2* 7 The evidence here is of a more slender nature,but the substance has the properties of a 6-aminopyrimidine-sulphonic acid : the disposition of the sulpho- and the ethyl groupis arbitrary and it is of course possible that the ethyl group shouldbe replaced by two methyl groups.H, YH,CH,*OH q - p %(I.) N<8==V HF TSOSH (11.1CH-S N=C*C2H,The sulphite cleavage of the vitamin, taken in conjunction withits other properties, led R.R. Williams2 to propose a tentativeformula (111) for vitamin B, hydrochloride.This formula contains a quaternary nitrogen atom and, althoughthe evidence from electrometric titration curves is 12R. R. Williams and A. E. Ruehle 10 consider that their results bythis method indicate the presence of such an atom.Early this year R. A. Peters l1 reported that aqueous solutionsof vitamin B, acquired a blue fluorescence on oxidation, and R.Kuhn, Th.Wagner-Jauregg, F. W. van Klaveren, and H. Vetter l2later isolated from yeast a yellow basic substance, thiochrome,C,,H,,ON,S, exhibiting an intense blue fluorescence in neutral oralkaline solution. The close relationship in empirical formulabetween thiochrome and the vitamin suggested that the formerAnn. Reports, 1934, 31, 328.E. R. Buchman, R. R. Williams, and J. C. Keresztesy, J . Amer. Chem.H. T. Clarke and S. Gurin, ibid., p. 1876.M. Tomlinson, J., 1935, 1030.Soc., 1935, 57, 1849.7 R. R. Williams, E. R. Buchman, and A. E. Ruehle, J . Amer. Chem. SOC.,* T. W. Birch and L. J. Harris, Nature, 1935, 135, 654.9 R. C. G. Moggridge and A. G. Ogston, Biochem. J., 1935,29,866; A., 668.10 J .Amer. Chem. Soc., 1935, 57, 1856.11 Nature, 1935, 135, 107; A., 415.l2 2. physiol. Chem., 1935, 234, 196; A,, 1026.* The formula as originally published (and in the Abstmct) gave the HCI1935, 57, 1093; A., 1035.attached to the S of the thiazole ring. This was undoubtedly a, misprintSTEWART AND STEWART. 403might be the substance responsible for the fluorescence noted byPeters and might arise from vitamin 13, present in the yeast. Thepreparation of thiochrome from vitamin B, by oxidation withalkaline potassium ferricyanide has been described by G. Barger,I?. Bergel, and A. R. Todd13 and with porphyrexide by R. Kuhnand H. Vetter.14 For thiochrome the former propose the structure(IV; R = H, R, = CzHs), whereas the latter authors favour aslightly different formula (IV; R = R, = CH,).N SN - C / \ v , *CH2*CH2*OHV .1 RV t-N-8*CH3N= R,Oxidation of vitamin B, with barium permanganate has beenstudied by A. Windaus, R. Tschesche, and R. Grewe,15 who haveisolated in small quantities some as yet unidentified pyrimidinederivatives.The vitamin formula (111) appears to be in agreement with theproperties of the substanoe, although some doubt exists as towhether the pyrimidine part carries one ethyl group in position 4,or two methyl groups in positions 2 : 4. Evidence from C-alkyldeterminations in favour of the former view is advanced by A. R.Todd, F. Bergel, and Karimullah.16 Final decision must, however,rest with synthesis.Indeed, since the complete identification by analytical methodsof the pyrimidine obtained by Williams is evidently very difficult,it seems likely that further advances in our knowledge of thestructure of vitamin B, will be made mainly by synthesis.Thereseems little doubt, however, that the formula proposed by Williamsis essentially correct.The antineuritic activity of crystalline vitamin B, towards humanberi-beri has been confirmed by R. a. Williams, R. E. Waterman,and J. C. Keresztesy,17 who report also that the crystals completelyprotect rats from polyneuritis in a dose of 1-2 x g. per day.A. J. Hermano and F. Eubanan 18 report the successful treatmentof it number of cases of human beri-beri with crystalline aneurin.Vitamin B2.-The chemistry of the flavins is fully reviewed else-where in this volume.19 It is sufficient here to mention that,l3 Nature, 1935, 136, 259; A., 1286; Ber., 1935, 68, [Bj, 2257.Ber., 1935, 68, [B], 2375.l5 2.physiol. Chern., 1935, 237, 98.Ber., 1936, 69, [B], 217.Science, 1935, 81, 535; A., 1035.l0 Philippine J. Xci., 1935, 57, 277; A., 1429.lQ P. 364404 BIOCHEMISTRY.although the synthetic arabinose derivative of alloxazine mentionedin the Report for last year 2O is undoubtedly physiologically active,it now appears that 6 : 7-dimethyl-9-d-riboflavin is chemicallyand physiologically identical with lactoflavin from milk.21 Theamyl derivative prepared last year,2z and a similar substance with anacetic acid 23 side chain, are inactive.It has been shown by H. TheorellZ4 that no yellow enzyme isformed when lactoflavin is added to the inactive (protein) constituentof the enzyme, but that the prosthetic group is a monophosphoricester of a flavin.Such a substance has been synthesised by R. Kuhnand H. who found it to behave similarly to the active groupof the yellow enzyme in an electric field, but to be less active incausing decolorisation of methylene-blue.P. Gyorgy 27 has confirmed his previous finding 26 of the inactivityof lactoflavin in preventing “ r a t pellagra,” for which anothersubstance, which he terms B,, is necessary. This substance ispresent in Peters’ “ charcoal eluate ” from yeast, and Gyorgysuggests that it may be a second natural pigment. In foodstuffsits concentration by no means parallels that of lactoflavin. Theseresults are confirmed by L.J. Harris28 and by H. Chick, A. M.Copping, and C. E. Edgar.29 Gyorgy recommends that the term“ B, ” be applied to the lactoflavin plus B,.Vitamin C.-A large number of papers have dealt with theoxidative methods of determining Z-ascorbic acid and with thevarious means available for overcoming its tendency to oxidisespontaneously and for removing the interfering substances (e.g.,glutathione) with which it is frequently associated.B. C. Guha and A. R. Ghosh30*31.32 report that rat tissues,especially liver, spleen, and kidney, are able to synthesise ascorbicacid in vitro from mannose, but not from glucose, fructose, galactose,2O Ann. Reports, 1934, 31, 329.21 H. von Euler, Y. Karrer, M. Malmberg, K.Schopp, F. Benz, B. Becker,and P. Frei, Helv. Chirte. Actu, 1935, 18, 522; A . , 760; R. Kuhn, K. Reine-miind, F. Weygand, and R. Strobele, Ber., 1935, 68, [B], 1765; A., 1382.22 R. Kuhn and F. Weygand, ibid., 1934, 67, [ B ] , 2084; A . , 262.23 R. Kuhn and H. Rudy, ibid., 1935, 68, [B], 300; A., 503.24 Biochem. Z . , 1934, 275, 37; k., 248; ibid., 1935, 375, 344; A . , 400; ibid.,25 Ber., 1935, 68, [B], 383; A . , 545.26 Ann. Reports, 1934, 31, 331.27 Biochem. J., 1935, 29, 741, 760, 767; A., 545.28 Ibid., p. 776; A., 545.Z g Ibid., p. 722; A., 544.Nature, 1934, 134, 739; A . , 1934, 131.31 Current Sci., 1934, 3, 251; A., 1934, 416.Nature, 1935, 135, 871 ; A., 903.1935, 278, 263; A . , 1024STEWART AND STEWART. 405xylose, or arabinose.C from external sources, unlike, e.g., the ox,whose tissues are unable to synthesise the vitamin in who.Vitamin D.-It is well established that a particular physiologicalactivity is frequently possessed by a group of related substances,although one (or a few) of the group may possess it in an out-standing degree.Among the hormones and vitamins this pheno-menon appears to exist to an extent which was unsuspected ayear or two ago. The fact that oestrogenic activityis possessed bya number of substances other than oestrone and oestriol has beenknown for some time, and has been commented on in these Reports ;33it was noted last year also that certain modifications in the structureof fhe testicular hormone and that of the corpus luteum resultedin increased rather than decreased activity.During the past yearseveral other substances, hormones and vitamins, have been shownnot to be alone in possessing their peculiar activities, and in onecase, that of vitamin D, the question has been raised as to whetherthe substance hitherto regarded as the vitamin is really entitled tobe so considered.W. C. Russell, M. W. Taylor, and D. E. Wilcox 34 found that,with chickens, in order to induce normal growth and producebone of normal composition it was necessary to supply a t least 144times as much vitamin D in the form of irradiated ergosterol as inthe form of cod-liver oil. Irradiated ergosterol was also lessefficacious than cod-liver oil in maintaining laying in pullets.M. J. L. Dols35 found that, whereas chickens were adequately pro-tected from rickets by a diet containing 2% of cod-liver oil, theaddition of irradiated ergosterol with a, vitamin activity (as measuredon rats) ten times as great was insufficient.Two hundred and fiftyinternational (rat) units of vitamin D per 100 g. of ration sufficedfor chicks when supplied in the form of cod-liver oil, unsaponifiablefraction of cod-liver oil, tunny oil concentrate, or irradiatedcholesterol, but 2500 units as irradiated ergosterol were insufficient.The obvious conclusion is that the aiitirachitic substance in the fishoils is not identical with calciferol. Similar results have beenobtained before, though perhaps in less conclusive form. It has,of course, to be remembered that other substances present in thefish oils, e.g., vitamin A, may be exerting some effect.Indeed,T. G. H. Drake, F. F. Tisdall, and A. Brown36 have found theopposite effect in infants-that irradiated ergosterol has a greaterRats are known to be independent of vitaminand guinea33 Ann. Reports, 1934, 31, 326.34 J. Biol. Chem., 1934, 107, 735; A., 1935, 261.35 Diss., Nijmegen, 1935; A . , 1430.36 Canadian &fed. Assoc. J., 1934, 71, 368; A . , 1935, 417406 BIOCHEMISTRP .antirachitic effect than an equal number of rat units of vitamin Din the form of cod-liver oil. The same criticism has been levelledagainst the work of F. Ender,37 who reported chemical and physicaldifferences between a vitamin D concentrate from natural sourcesand the substance obtained by irradiating ergosterol.0. Rygh 38has now reported that vitamin D concentrates from the liver fats ofa woman, a cow, and numerous species of fish were equally effectivein preventing rickets in chicks and agreed further in showing noabsorption maximum at 260-270 mp, no rotation in alcoholicsolution, no reaction with maleic anhydride, and complete esterific-ation in 10 days with phthalic anhydride and pyridine. Thesefindings indicate quite definitely that antirachitic activity is notconfined to calciferol, and strongly suggest, indeed, that calciferolis not the natural vitamin. The latter conclusion, however, muststill be regarded with some reserve, in view of the wide distributionof ergosterol. The nature of the antirachitic substance in theliver-oil concentrates of Rygh is still unknown.I n addition to calciferol and a naturally occurring substancenot identical with it, other, artificially prepared, substances arenow known to be antirachitic.A reduction product of ergosterol(22 : 23-dihydroergosterol) becomes strongly antirachitic whenheated, and further evidence that the side chain is of relativelylittle importance in determining activity is afforded by the factthat irradiation of 7 : 8-dehydrocholesterol (side chain of 8 insteadof 9 C) gives a product containing 8000 antirachitic units per mg.39Dehydrocholesterol has the same spectrum as ergosterol, and isstrongly lavorotatory; it would therefore appear not to be theprecursor of the substance which Rygh believes to be the naturalvitamin.The constitution of calciferol is not yet completely determined,although the different workers agree that it contains a three-ringsystem, ring scission taking place during irradiation in the con-version of IumiSterol into tachysterol, and the four-ring systembeing re-formed when calciferol is converted into pyrocalciferol.0. Rosenheim and H.King40 favour a formula (V) having a 10-membered ring, with three conjugated double bonds, of which oneis in the original ring C of the sterol system.I. M. Heilbron, K. M. Samant, and F. S. Spring *l also suggest aa7 2. Vitaminforsch., 1933, 2, 241.38 Nature, 1935, 136, 396, 662 ; A . , 1430.39 A. Windaus, H. LettrB, and F. Schenck, Annalen, 1935, 520, 98; A .,4O Chew. and Ind., 1935, 699; A., 1120.41 Nature, 1936, 135, 1072; d., 1036.1363STEWART AND STEWART. 407three-ring formula. I. M. Heilbron and 3'. S. Spring42 agree withRosenheim and King that the change from tachysterol to calciferolinvolves a change in the position of the double bonds, but do notthink the position of these bonds can yet be decided with certainty.From consideration of the effects of mild oxidation on calciferolthey hold that the ring system shown in (VI) must be present incalciferol, and that one of the double bonds occupies the 5 : 6-position.Windaus 43 suggests a similar ring scission.Vitamin E.-Although vitamin E has not yet been isolated,increased knowledge of its chemical character should lead beforelong to its preparation in a pure state.It is known to be anBenzoyl and acetyl deiivatives of concentrates fromvitamin-E-active oils show the vitamin activity, but methyl orethyl ethers, and also a urethane obtained by the action of phenylisocyanate, do not. Alcoholic potassium hydroxide, however,hydrolyses the urethane and restores activity. The vitamin con-centrates exhibit an absorption band at 294 mp, but H. s. Olcott 46concludes that this is not due to the vitamin, since its intensity is notproportional to the vitamin activity. Hydrogenation of the activeconcentrates reduces the iodine va'lue to 26 and does not destroythe active substance.J. C. Drummond, E. Singer, and R. J. Macwalter 46 have obtaineda concentrate, active in a daily dose of 0.1 mg., and evidently con-taining a hydroxyl group, since it is capable of acetylation. Theydescribe their preparations, however, as showing an absorptionband at 294 mp, the intensity of which is proportional t o the vitaminactivity of the preparation.They found that acetylation of theiractive product yielded p-amyrin acetate, which was inactive andgave little absorption. This is, however, not the vitamin, sinceOlcott found that his acetylated product was active, and F. E.Askew 47 from examination of surface films has concluded that42 Chem. and Ind., 1935, 795; A., 1235.43 Cf. H. Muller, 2. phyaiol. Chem., 1935, 233, 223; A,., 1037.44 H. S. Olcott, J . Bid. Chem., 1935, 110, 695; A . , 1287.4 5 Ibid., 1934, 107, 471; A., 1935, 129.'16 Biochem.J., 1935, 29, 456; A . , 418.47 Ibid., p. 472; A., 418408 BIOCHEMISTRY,p-amyrin differs from vitamin E, which, however, may be a poly-cyclic compound with a water-attracting group near one end ofthe molecule.The Sex Hormones.The number of publications dealing with the sex hormones hassuffered no diminution. The interest still lies mainly in the chemicalconstitution of the hormones and its relation to physiologicalactivity.Testicular Hormone.-It was) reported last year 48 that andro-sterone, prepared from urine and from epidihydrocholesterol,appeared to be somewhat specific, although its reduction product,androstanediol, was even more active in promoting comb growthin the capon. During the year under review the number of activesubstances has been considerably increased, both by isolation fromnatural sources and by artificial preparation.Androsterone (VII) is saturated, and has the spatial arrangementshown ; its stereoisomeride, isoandrosterone (VIII) ,49 obtainablefrom dihydrocholesterol or stigmasterol, is about one-tenth asactive in the comb-growth test ; 5O but the corresponding compoundswith the cis-arrangement of rings A and B are inactive.Theparticular stereo-position of the hydroxyl group in androsteronedoes not, therefore, appear to be essential for physiological activity,and, indeed, androstanedione 50t 52 (IX) (isolated from testes 51)is about two-thirds as active as androsterone in promoting combgrowth (in vivo reduction may occur, of course). A point of someimportance arises here, for when tested by its power of stimulatingvesicular growth in immature or castrated rats, androstanedione isfound to be somewhat more active than androsterone ; on the otherhand, androstanediol (X) is four or five times as active as andro-sterone in promoting comb growth,53 but only slightly more activein promoting vesicular growth.54It seems, further, that, although compounds with the cis-arrange-ment of rings A and B are inactive, the presence of a trans-arrange-4 8 Ann.Reports, 1934, 31, 323.49 A. Butenandt and H. Cobler, 2. physiol. Chem., 1935, 234, 218; A.,50 L. Ruzicka and A. Wettstein, Helv. Chim. Acta, 1935, 18, 986; A.,51 A. Ogata and S. Hirano, J . Pharm. SOC. J a p n , 1934, 54, 199.59 A. Butenandt and K.Tschernig, 2. physiol. Chem., 1934, 229, 185; A . ,1935, 413.53 L. Ruzicka, M. W. Goldberg, and J. Meyer, Helv. Chim. Acta, 1935,18, 210; A., 346; A. Butenandt and K. Tschernig, 2. physiol. Chem., 1935,234,224; A., 1033.1033.1125.54 E. Tschopp, Nature, 1936, 136, 259; A., 1285STEWaRT AND STEWART. 409ment is not essential, for several active unsaturated substances havebeen discovered. Butenandt 55 isolated from urine isodehydro-androsterone (XI), which was about as active as isoandrosterone 56and was shown by its preparation from cholesterol to have thestructure (XI).50* 57 On reduction it gave the only slightly activedihydroxy-compound (XII), 58 but oxidation produced andro-stenedione 59 (XIII), which is less active than androsterone in thecomb-growth test (about two-thirds) and about twice as active inthe rat test.O=(XI.) (XII.) (XIII.)Most active of all is testosterone (XIV), isolated from testes byand by Ruzicka,625 5 A. Butenandt and H. Dannenbaum, 2. phy8iol. Chem., 1934, 229, 192;5 6 Idem, and G. Harrisch and H. Kudszus, ibid., 1935, 237, 52.5 7 E. S. Wallis and E. Fernholz, J . Amer. Chem. Xoc., 1935, 57, 1379, 1504,5 * A. Butenandt and G. Hanisch, Z. pi1,ysioZ. Chern., 1935, 237, 89.59 A. Butenandt and H. Kudszus, ibid., p. 75.60 K. David, E. Dingemanse, J. Freud, and E. Laqueur, ibid., 1935, 233,61 A. Butenandt and G. Hanisch, Ber., 1935, 68, [B], 1859; A., 1370.62 L. Ruzicka and A. Wettstein, Helv. Chim. Acta, 1935, 18, 1264; A.,Laqueur et aZ.,60 and shown by Butenandt 58*A., 1935, 413.1511; A., 1125, 1242.281; A., 1033.1371410 BIOCHEMISTRY.who prepared it from isodehydroandrosterone, to have the structureshown, which is remarkably similar to that of progesterone (XV).It is about five times as active as androsterone in the comb-growthtest and about twenty times as active in promoting vesicular growth.AT gT (XV.)(XIV.) M XO= (q$'J /\ o=(/The figures representing relative activities cannot be given morethan approximately, for, as in all biological tests, there is a con-siderable margin of error, and such conditions as time elapsing sincecastration, duration of test, age and breed of animal, size of dose(Le., whether an average or a maximal effect is sought) all affectthe results of the test.54* 63 There seems no doubt, however, thattestosterone is the most active substance yet obtained in this group,and the tendency is to regard it as the true hormone, and to considerandrosterone and the other naturally occurring related substancesas products of its metabolism.!The Corpus Luteum Hormone.-It has been suggested that thenames a- and p-progesterone be used for the high- and the low-melting form, respectively, of the corpus luteum hormone, previouslyknown as progestin or luteo~terone.~~ The two forms, it is nowagreed, are chemically and biologically identical : W.M. Allenand S. R. M. Reynolds 65 have shown that both suppress uterinemobility in rabbits, and that both inhibition of motility and pro-gestational proliferation of the endometrium are produced by oneand the same hormone.Progesterone still seems to be remarkablyspecific. Reduction of both keto-groups or of the C,, keto-groupyields inactive compounds,66 and a second hydroxy-ketone, aEEo-pregnan-3-01-20-0ne, isolated from corpus luteum is also inactive.67Not only is activity dependent on the presence of both ketonegroups, but the presence and the position of the double bond areboth important. Pregnandione, the saturated diketone corre-sponding to progesterone, is inactive and has been converted by63 L. Ruzicka, M. W. Goldberg, and H. R. Rosenberg, Helv. Chim. Acta,1935,18, 1487.64 W. M. Allen, A. Butenandt, G. W. Corner, and K. H. Slotta, 2. physiol.Chem., 1935,235, 1; Nature, 1935,136,303; A., 1284.1 3 ~ Science, 1935, 82, 155.66 Ann.Reports, 1934, 31, 327.6 7 A. Butenandt and L. Mamoli, Ber., 1934, 67, [B], 1897; A., 1935, 215;E. Fernholz, Z. physiol. Chem., 1934, 230, 185; A., 1935, 215STEWART AND STEWART. 41 1A. Butenandt and L. Mamoli 68 into a singly unsaturated diketone(believed to be Al-allopregnene-3 : 20-dione) which is devoid of;tctivity.Chemistry of Muscle.Reference was made last year G9 to attempts to co-ordinate thevarious chemical changes known to be associated with muscularactivity. Much important work has been published during 1935on the details of lactic acid formation ; it is, however, in the continu-ation of the attempts at co-ordination that the main interest ofthe year’s work lies. The position a t present is by no means clear,for the problem of muscle chemistry involves the problem of thechemistry of muscular contraction, and of this, glycogenolysisforms only a part.The main progress so far is in the co-ordinationof the changes in the phosphorus-containing compounds with lacticacid formation and, generally speaking, in the clear recognition ofthe key position occupied by these substances and of glycogenolysisas a series of reactions involving the transference of phosphate fromone molecule to another.Adenylic acid pyrophosphate is apparently required for theformation of phosphoric esters of carbohydrate (acting as phosphoricacid donator), but the only other stage in lactic acid formation a twhich co-enzyme is necessary appears to be the hydrolysis ofphosphopyruvic acid.At this stage it is now evident that adenylicacid is probably the true co-enzyme (acting as phosphoric acidacceptor).P. Ostern et aZ.70 have shown that autolysed frog-muscle extractslowly hydrolyses phosphoglyceric acid, but if adenylic acid isadded, adenylic acid pyrophosphate is slowly formed and, withphosphopyruvic acid, accounts for all the phosphorus. In absenceof creatine, phosphoglyceric acid is converted in part into phospho-pyruvic acid and no PO4”’ is liberated; in this case adenylic acidthen causes rapid production of adenylic acid pyrophosphate to anextent which accounts for half the phosphorus of the phospho-glycerio acid. It is therefore concluded that the “ dephosphoryl-ation ” of phosphoglyceric acid takes place in two stages and that(contrary to the earlier hypothesis of J.K. Parnas, P. Ostern, andT. Mann 69) creatine-phosphoric acid is not an obligatoryintermediary.[It is probable, from studies with natural and with synthetioG 8 Ber., 1935, 68, [B], 1860; R., 1370.69 Ann. Reports, 1934, 31, 338.70 P. Ostern, T. Baranowski, and 3. ‘Reis, Corn@. rend. SOC. Biol., 1935,118, 1414; A., 778412 BIOCHEMISTRY.phosphopyruvic acid, 71* 729 73* 74 CH2:C( O*P0,H)*C02H, that3-phosphoglyceric acid (formed from triose phosphoric acid) isconverted by the action of a “ phosphoglyceromutase ” into 2-phos-phoglyceric acid ; that this, under the influence of “ enolase,”yields phosphopyruvic acid; and that phosphoric acid is thentransferred to adenylic acid (or creatine) with liberation of pyruvicacid.]Similar results have been published still more recently by P.Ostern, T.Baranowski, and J. R e i ~ , ~ ~ who find that dephosphoryl-ation of phosphoglyceric acid can occur only in presence of adenylicacid or adenylic acid pyrophosphate : if creatine also is present,formation of phosphocreatine occurs only under conditions whichlead to an accumulation of adenylic acid pyrophosphate fromadenylic acid. Under certain conditions in the system, phospho-glyceric acid-adenylic acid-creatine-phosphocreatine, there may betransference of phosphate from molecule to molecule (with liberationof pyruvic acid) without the liberation of any PO4’”.D. M. Needham and W.E. van Heyningen 76 also have found thatphosphoglyceric acid is converted into pyruvic acid by dialysedmuscle preparations in the presence of adenylic acid or adenylicacid pyrophosphate, though not in the presence of creatine withoutadenylic compounds. When adenylic acid was present, even with-out creatine, adenylic acid pyrophosphate was formed in amountequivalent to the whole of the adenylic acid present ; when creatinewas present with adenylic acid, phosphocreatine was formed aswell. By using extracts dialysed for a long time so as to destroythe enzyme responsible for the hydrolysis of adenylic acid pyro-phosphate t o adenylic acid and phosphoric acid, Needham andvan Heyningen were able to show that in all probability adenylicacid pyrophosphate itself is incapable of inducing dephosphorylationof phosphoglyceric (or phosphopyruvic) acid, and that adenylic acidis the real co-enzyme in this reaction.This conclusion, thoughcontradicting the earlier statement of K. Lohmann and 0. Meyer-hofY77 is in agreement with the views recently published by 0.Meyerhof and Lehmann.78 Adenylic acid pyrophosphate can,usually, function as a co-enzyme on account of its rapid hydrolysisto adenylic acid.a1 W. Kiessling, Ber., 1935, 68, [B], 243; A . , 471.72 Idem, ibid., p. 597; A., 731.73 0. Meyerhof and W. Kiessling, Biochem. Z . , 1935, 280, 99; A., 1418.‘4 R. Akano, ibid., p. 110.75 Ibid., 1935, 279, 8 5 ; A., 1150.a6 Biochem. J . , 1935, 29, 2040; A., 1278.7 7 Biochem. Z . , 1934, 271, 264.7 8 Naturwiss., 1933, 21, 337STEWART AND STEWART.413Since the reaction, phosphoglyceric acid + creatine = pyruvicacid + phosphocreatine + H,O, is now shown not to take place,and since J. K. Parnas et ~ 1 . ~ ~ have demonstrated an increase inphosphocreatine when frog-muscle pulp poisoned with iodoacetateis incubated with phosphoglyceric acid (confirmed by the authorscited above), Needham and van Heyningen and also J. K. Parnasand P. Ostern make the suggestion, which is in agreement withthe results of Ostern et aZ.70 as well as their own, that phospho-creatine may be synthesised by a reverse Lohmann reaction, i.e.,adenylic acid pyrophosphate -+- creatine = phosphocreatine +adenylic acid.Needham and van Heyningen suggest further that, since this isa termolecular reaction, it may proceed in two stages, with inter-mediate formation of adenosine diphosphate , which has been foundby I<.Lohmann in heart and smooth muscle and whose reactionwith phosphoarginine has been demonstrated in crab muscle. Thissuggestion is an interesting one, for it is to be supposed that the(in skeletal inuscle) exceedingly labile adenosine diphosphate wouldoccur transitorily as an intermediate in the formation of adenosinetriphosphate (adenylic acid pyrophosphate) from adenylic acid.It would thus account for the finding, recorded above, that phospho-creatine synthesis occurs in circumstances which lead to accumulationof adenylic acid pyrophosphate and also for the fact that ordinarily,in resting muscle, the amount of phosphocreatine slowly decreases.The present position is, therefore, that glycogenolysis does notnecessarily involve the intervention of phosphocreatine, but consistsessentially in (1) the transference of phosphate from adenylic acidpyrophosphate to carbohydrate ; (2) the production of glycero-phosphoric acid and phosphopyruvic acid from the hexose diphos-phoric acid so formed ; (3) the dephosphorylation of phosphopyruvicacid, the phosphate being transferred t o the adenylic acid formed in(1) ; (4) the reduction of pyruvic acid to lactic acid with simultaneousoxidation of glycerophosphoric acid.In addition to the co-enzymes adenylic acid and adenylic acidpyrophosphate, which take part in certain reactions in stoicheio-metric proportions, the glycogenolysis system also requiresmagnesium ions.Their function is still obscure. Nor is it knownhow inorganic phosphate may enter or leave the system (as it doesin vitro at least).The relation of phosphocreatine to these reactions is by no means79 J. K. Parnas, P. Ostern, and T. Mann, Biochem. Z . , 1934, 275, 74; A . ,80 Ibid., 1935, 279, 94; A., 1150.81 Angew. Chem., 1935,48, 165.1935, 239414 BIOCHEMISTRY.clear. It is, apparently, not hydrolysed by a specific enzyme,but liberates creatine by transferring its phosphate t o adenylica ~ i d . 6 ~ On the other hand, it can, in certain circumstances, beresynthesised at the expense of adenylic acid pyrophosphate (orpossibly adenosine diphosphate) . It has, therefore, been describedas a reserve of phosphate, a phosphate donator for the rapid re-synthesis of adenylic acid pyrophosphate.80 This, however, leavesunexplained many facts of muscle chemistry, and a further clarific-ation of the position is required.The question of ammonia production has received attention fromJ.K. Parnas and his collaborators. They are of the opinion thatadenylic acid, but not adenylic acid pyrophosphate, may undergodeamination,s2 but experiments (e.g., on the inhibition by phospho-glyceric acid of ammonia production in muscle pulp poisoned byfluoride or iodoacetic acid B3* 84) lead them to believe that thisdeamination takes place when glycogenolysis is completed, i.e.,that adenylic acid is preferentially rephosphorylated to adenylicacid pyrophosphate.During the resting stage re-amination ofinosinic acid is possible.s2Fat Metabolism.It has long been held, as suggested by Knoop, that oxidation offatty acids in vivo takes place by successive oxidations of the(3-carbon atom, and, though it has been questioned whether thisis the sole mode of oxidation, p-oxidation has been generally acceptedas accounting for the main part of fatty acid oxidation. Recently,definite proof has been advanced that other processes of oxidationoccur, and even the general theory of p-oxidation, at least in itsusual form, has been called into question.P. E. Verkade and J. van der Lee 85 found that, after the feeding(to man) of triglycerides of fatty acids containing from 8 to 12 carbonatoms, the corresponding dicarboxylic acids were excreted in theurine. There was no difference between the fatty acids, attributableto their possession of an odd or an even number of carbon atoms,but the formation of dicarboxylic acid was greatest in the case oftricaprin.When tricaprin was fed, the urine contained not onlysebacic acid, but also small amounts of the lower dicarboxylic acids,adipic and suberic. These results Verkade and van der Lee explained82 J. K. Parnas, P. Ostern, and T. Mann, Rocz. Chem., 1934, 14, 1358; A . ,133 T. Mann, Biochem. Z., 1935, 277, 380; A., 890.84 Idem, ibid., 1935, 279, 82; A., 1150.86 Biochern. J . , 1934, 28, 31; A., 1934, 441; 2. physiol. Chem., 1934, 227,1935, 387.213; A,, 1934, 1393STEWART AND STEWART.415as due to combined O- and P-oxidation, the possible routesbeing :CH,*[CH,],*CO,H -% H0,~[CH2]8*C0,H0 P.1” P CH,*[CHd 6*C0,H H 0,C*[CH2] ,*C02HCH,*[CH,],-CO,H -%- H0,C*[CH2] 4*C0,HThe existence of a-oxidation has been confirmed by B. Flaschen-triiger, K. Bernhard, C. Lowenberg, and M. Schlapfer,86 who, afterfeeding a-methylbenzosulphaminolauric acid (to dogs) , isolated thesimilarly substituted adipic acid from the urine. The authorspostulate an initial w-oxidation, followed by three successivep-oxidations. B. Flaschentrager and K. Bernhard have alsoobtained sebacic acid from dog’s urine after feeding sodium decoateand sodium laurate (0.5-1.0% of the fatty acid fed) and in thecase of sodium decoate they obtained suberic acid as well. Similarresults were obtained with methyl decoate and with ethyl (but notmethyl) laurate.also have obtained evidenceof direct oxidation, with rupture of the chain, at the double bond ofan unsaturated acid, for they found that after ingestion of tri-AC-undecenoin, sebacic acid was excreted in the urine.They wereunable, however, to isolate any definite acids after the ingestion ofolive or rape oil.M. Jowett and J. H. Quastel 89 have studied the oxidation offatty acids by liver slices. They first investigated the productionof acetoacetic acid from butyric, crotonic, and P-hydroxybutyricacids, and from mixtures of these. From (inter a h ) the fact thafcrotonic and butyric acids appeared to compete for oxidation,whereas hydroxybutyric acid showed a partial additive effect, theyconcluded that hydroxybutyric acid was not an intermediary inacetoacetic acid formation.Since, moreover, acetoacetic acid wasproduced more rapidly from butyric than from crotonic acid, sincecertain inhibitors affected oxidation of crofonic acid more than thatof butyric acid, and since the optimal rate of oxidation required ahigher concentration of crotonic than of butyric acid , they decided86 2. physiol. Chem., 1934, 225, 157; A., 1934, 1027.87 Natumoiss., 1935, 23, 356; A., 1015; Helv. China. Acta, 1935, 18, 962;A,, 1151.88 2. physiol. Chem., 1934, 230, 207; A., 1935, 242; Proc. K. Akad.Wetensch. Amsterclam, 1934, 37, 590; A., 1935, 390.*B Biochem. J., 1935, 29, 2143; A., 1408.P.E. Verkade and J. van der Le416 BIOCHEMISTRY.against desaturation with formation of crotonic acid as the firststage in the oxidation of butyric acid. They suggest an activationof butyric acid to a product identical with activated crotonic acid :CH,*CH,*CH,*CO*O’ --+ CH,&CH,*CO*O’ + 2HCH,CH:CH*CO*O‘ CH,*CO*CH,*CO*O’CH,*CH( OH) *CH,*CO*O’According to this view, then, oxidation of the fatty acid chainconsists in production of a keto-acid by addition of oxygen afterdesaturation to an activated ion which exists only in associationwith the enzyme.Jowett and Quastel 90 have further investigated the oxidation,by liver slices, of normal saturated fatty acids containing from 2 to10 carbon atoms. They find that, with guinea-pig liver, all exceptpropionic acid yield acetoacetic acid, which is probably the onlyketo-acid produced in significant amount. The acids containingan odd number of carbon atoms produce only small amounts ofacetoacetic acid; hexoic and octoic acids produce about one mol.of ketonic compounds per mol.of acid; decoic acid produces ratherless, butyric acid considerably less, and acetic acid even less thanthe higher odd-numbered fatty acids. The fatty aleids higher thanvaleric, especially those with an even number of carbon atoms,produce some “ fixed ” acid, which is not acetoacetic or hydroxy-butyric acid but has not been positively identified; with acetic,valeric, and propionic acids, however, there is a disappearance of“ fixed ” acid, and with butyric there is a very slight loss.Withrat liver, sodium benzoate inhibits acetoacetic acid production fromthe even-numbered fatty acids, the inhibition being greatest withbutyric acid and decreasing as the series is ascended. N. L. Edson 91also has found that in liver slices odd-numbered fatty acids give riseto @-ketonic acid (acetoacetic acid, according to Jowett and Quastel),though only to about one-third the extent of the even-numberedacids, and this fact alone is clearly incompatible with the idea ofsuccessive p-oxidations as the only mode of breakdown of fattyacids. J. S. Butts et ~ 2 . 9 ~ support this conclusion with experimentson the intact rat, suggesting that octoic acid may be oxidised t otwo molecules of ketonic compounds. Jowett and Quastel point90 Biochem.J., 1935,29, 2159; A., 1408.91 Ibid., p. 2082; A., 1273.92 J. S. Butts, C. H. Cutler, L. Hallman, and H. J. Deuel, jun., J . Biol.Chem., 1935, 109, 597; A., 891STEWART AND STEWART. 417out that the difficulty cannot be overcome by supposing the pro-duction, by p-oxidation, of acetic acid, which might then be trans-formed into acetoacetic acid, since their quantitative results areagainst such a supposition. Taking into account any possibleformation of acetoacetic acid from acetic acid, they consider thelower formation of acetoacetic acid by butyric than by hexoic,octoic, and decoic acids, together with the differing inhibiting effectof sodium benzoate, to be fatal to the p-oxidation theory. Toreplace it, they suggest a hypothesis of " multiple alternate oxid-ation," according to which the fatty acids undergo an oxidationthroughout the chain, alternate carbon atoms being affected.Thusoctoic acid may be supposed to be oxidised at the p-, 6-, and <-carbonatoms simultaneously (possibly at the a-, y-, and &-carbon atoms tosome extent), and valeric acid might undergo either p-oxidation oroxidation at the a- and y-carbon atoms. Oxidation at the p-, 6- . . .atoms is to be considered the main process in the oxidation of thehigher fatty acids.The liver slice technique has been applied by C. L. Gemmill andE. G. Holmes 93 to the vexed question of the conversion of fat intocarbohydrate. They find that slices of liver from rats fed on butterhave an R.Q. of 0.58 (0.79 for slices from rats on normal diet), andthat, after being shaken for 3 hours in sodium bicarbonate-Ringersolution at 37", the slices show an increased carbohydrate content.The glycogen content of the livers of rats fed on butter falls almostto zero on the first day of the diet, and then gradually increases to amaximum of 1% on the fourth or fifth day. Although the latterresults could conceivably be explained by transference of glycogenfrom other tissues, those with liver slices afford strong evidence infavour of carbohydrate production from fat (though the possibilityof formation from protein is not definitely eliminated).Amino-acids.Last year 94 the synthesis was reported of four diketopiperazineswhich underwent hydrolysis by digestive enzymes.Two of them,containing amino-dicarboxylic acids, were hydrolysed by trypsinand papain, and the others, containing diaminopropionic acid, werehydrolysed by pepsin. Y. Tazawa 95 has now obtained d-arginineanhydride tetrahydrochloride and d-lysine anhydride dihydro-chloride. These substances are hytfrolysed smoothly by pepsin,but not by trypsin or papain. It seems, therefore, that substituted93 Biochem. J., 1935, 29, 338; A., 523.g4 Ann. Reports, 1934, 31, 342.es Acta Phytochim., 1935, 8, 331; A., 966.REP.-VOL. XXxII. 418 BIOCHEMISTRY.diketopiperazines are susceptible to enzymic hydrolysis providedthe side chains contain suitable amino- or carboxy-groups. Thisremoves the main objection to accepting the diketopiperazine ringas part of the normal structure of proteins.Anhydrides have, ofcourse, frequently been isolated from protein hydrolysates, thoughthe methods employed have left open the possibility that they maybe artefacts. Indirect evidence of their existence in the proteinmolecule is suggestive but inconclusive. The finding that they maybe hydrolysed by digestive enzymes will surely stimulate the searchfor more conclusive evidence of their actual existence in the proteinmolecule.New reagents and methods for determining the arrangement ofthe amino-acids within the protein molecule are being sought.S. Gurin and H. T. Clarkeg6 have prepared the benzenesulphonylderivative of gelatin and succeeded in hydrolysing the peptidelinkages without splitting off the benzenesulphonyl group.Fromthe yield of E-benzenesulphonyl-cE-lysine obtained, they concludethat a t least 50% of the free NH, in gelatin is accounted for by theE-NH, of lysine, and that not more than 0.5% can be due to mono-amino-acids. M. Bergmann 97 has used “ rhodanilic acid,”[Cr(CNS),(C,H5*NH,),]H, which gives a sparingly soluble crystallinesalt with proline. On the basis of analysis of gelatin with thisreagent, he suggests that every sixth amino-acid in the chain isproline, every ninth hydroxyproline, and every third glycine.‘D. Blumenthal and H. T. Clarke 98 distinguish two types of sulphurcompound, one oxidised t o SO,” by bromine and giving lead sulphideon treatment with lead carbonate, the other oxidised to SO,” byfuming nitric acid and not affected by lead carbonate.Applyingthis result to protein hydrolysates, they find that, besides cystineand methionine , two other sulphur-containing substances are present,one of each type. A new sulphur-containing amino-acid is claimed tohave been isolated by A. G. vanVeen and A. S. H ~ m a n , ~ ~ who obtainedit in 1.60/, yield from the djenkol bean and named it djenkolic acid.It has the formula CH,[S*CH,*CH(NH,)*CO~H], and on treatmentwith concentrated sulphuric acid gives cystine and simple decom-position products.An interesting amino-acid is canavanine , which was isolated in1929 by Kitagawa,l who considered it to beNH,*C( :NH)*NH*O*CH,*CH,*CH( NH,)*CO,HB G J . Biol. Chem., 1934, 107, 395; A . , 1935, 101.B7 Ibid., 1935, 110, 471 ; A ., 1140.98 Ibid., p. 343; A . , 1140.BB Rec. trav. chim., 1935, 54, 493 ; A., 966.M. Kitagawa and T. Tomita, Proc. I m p . Acad. Tokyo, 1929, 5, 380;A., 1930, 121STEWART ANT, STEWART. 419and showed that it resembled arginine in being able to take part inthe production of urea from ammonia and carbon dioxide. Theconstitution of canavanine has been confirmed by J. M. Gullandand C. J. 0. R. Morris,, who found that chloramine-T converted i tinto a mixture of glyoxal and tartronic semialdehyde, and hotconcentrated hydrobromic acid produced a-amino-y-butyrolactonehydrobromide, ammonia, and guanidine.Glutathione.The tripiptide isolated by (Sir) F. G. Hopkins in 1930 and almostsimultaneously by E. C. Kendall, B. F. McKenzie, and H.L. Mason *has been shown by a number of workers to be y-glutamylcysteyl-glycine. This constitution has now been confirmed by synthesis.The synthesis by C. R. Harington and T. H. Mead is founded upont'he benzylcarbonato-method of M. Bergmann and L. Zervas,6 butits success is due to the discovery of a suitable means of removingthe benzylcarbonato-residue, which was not achieved, in the case ofcysteine-containing substances, by the original method of catalyticreduction. Reduction by phosphonium iodide in acetic acid waseffective, however, and so overcame the main stumbling block in avery difficult synthesis. N-Carbobenzyloxycystine was converted$?H,*SH roc1 VO*NH*$IH*CO*NHTH-NH, -t 5 3 3 2 FH2 TH2 g;Et CO*NH*CH,*CO,Et FH2 +$?H2 SHyH*NH*CO*O*C,H, $IH*NH*CO*O*C,H,C0,Me C0,Me(XVIII.)YOON H*C)H*CO*NH*CH,*CO,HCH2 CH,*SHYH-NH,C0,Hinto the acid chloride, which was coupled with glycine ester, and theproduct on reduction with phosphonium iodide yielded cysteylglycylester (XVI) (isolated as hydriodide). The a-monomethyl ester ofN-carbobenzyloxyglutamic acid was obtained by the action ofsodium methoxide in methyl alcohol on N-carbobenzyloxyglutamicI .c.(XVI.) (XVII. )(XIX.)TH2J., 1935, 763; A., 966.J . Biol. Chem., 1929, 84,269; A., 1929, 1491.4 Ibid., p. 657; A., 1930, 113.5 Biochem. J., 1935, 29, 1602; A., 1110.ti Ber., 1932, 65, [B], 1192; A., 1932, 935420 BIOCHEMISTRY.anhydride.' It gave the corresponding acid chloride (XVII) ontreatment with phosphorus pentachloride, and this was coupledwith cysteylglycyl ester 60 give the compound (XVIII).Thepurification of this substance was difficult, as was the hydrolysis ofthe ester linkage, which was finally accomplished in alkaline aqueousdioxan solution. Reduction of the resulting acid by means ofphosphonium iodide gave the tripeptide 7-glutamylcysteylglycine(XIX) in small yield. The synthetic substance was identical inevery respect with a sample of glutathione from natural sources.Knowledge of the functions of glutathione in the living cell is stillin an unsatisfactory state, though it is steadily increasing. (Sir) F. G.Hopkins and K. A. C. Elliott * found that fresh chopped liver,especially when obtained from well-fed animals, was capable ofreducing glutathione, and that this property was largely lost if thetissue was heated at 52" for an hour.These results suggested thatcertain enzyme systems were concerned and that glutathione couldact as a hydrogen carrier. P. J. G. Mann9 found that glucosedehydrogenase reduced glutathione under anzerobic conditions,and N. U. Meldrum 10 observed a reduction by intact mammalianerythrocytes in presence of glucose. Now, N. U. Meldrum andH. L. A. Tarr 11 have reported experiments showing that the isolateddehydrogenase system of Warburg and Christian reduces theoxidised peptide to the sulphhydryl form both anzerobically andaxobically in the presence of hexosemonophosphoric acid, phospho-hexonic acid, or fructosediphosphoric acid. When hexosemono-phosphoric acid is being oxidised in the presence of molecularoxygen, the reaction velocity is roughly proportional to the con-centration of glutathione, which is, therefore, acting as an oxygencarrier. In vitro, too, it has been stated by C.C. Palit and N. R.Dhar,12 the oxidation of glucose by atmospheric oxygen at roomtemperature is induced by addition of glutathione. It is pointedout by N. U. Meldrum and H. L. A. Tarr that so far the only enzymesshown to be involved in glutathione reduction are intimately con-nected with carbohydrate oxidation.It has, of course, been known for some time that glutathione isthe co-enzyme of the glyoxalase system (0. E. Woodwardl3 hasrecently based a method for the determination of glutathione onthis fact) and again, glutathione is linked with carbohydrate7 J.Melville, Biochern. J., 1935, 29, 179.Proc. Roy. SOC., 1931, [B], 109, 58; A., 1931, 1182.Biochem. J., 1932, 26, 785; A., 1932, 880.10 Ibid., p. 817; A., 1932, 880.11 Ibid., 1935, 29, 108; A., 249.l2 J. Indian Chern. SOC., 1934,11, 661 ; A,, 1834, 1314.13 J . BioZ. Chem., 1935, 109, 1 ; A., 784STEWART AND STEWART. 421metabolism. Experiments by R. Gaddie and C. P. Stewart l4suggest that glutathione is concerned in the formation of methyl-glyoxal from carbohydrate, as well as in its conversion into lacticacid. As supporting the idea thitt glutathione is specially con-cerned in carbohydrate breakdown, both zerobic and anzerobic,it is perhaps significant that K. Wachholder and W.Quensell5find the highest glutathione concentration in those muscles whichare most often required for prolonged exercise, e.g., the extensorsused for maintenance of posture.Chemoth prapy .Recent years have witnessed keen competition in matters of costand efficiency between naturally occurring and synthetic drugs,the latter having the initial advantage of being in general muchsimpler in chemical constitution than the materials they are intendedto supplement or supersede.In the treatment of malaria interest has continued to centreround the relative merits of the I. G. Farbenindustrie A.-G. sub-stances atebrin (XX) and plasmoquin (XXI),lG the Russian productplasmocide * (XXII),l' and the cinchona alkaloids, particularlyNNH N Meom NH NNHhHMe*[ CH,],*NEt, (!?€We*[ CH,I,.NEt, [ hH,I,*NEt,(XX-1 (XXI.) (XXII.)quinine. The fact that plasmoquin is essentially antigametocidalin its mode of action and quinine and atebrin are primarily anti-schizonts l8 suffices to account for the continued investigation of thel4 Biochern. J., 1935, 29, 2.101; A., 1278.l5 PfEiigers Archiv, 1934, 235, 7 0 ; A., 1935, 645.l6 L. Knunjantz, Bull. Acad. Sci. U.R.S.S., 1934, 8, No. I, 153, 165; B.,1935, 650; H. Mauss and F. Mietszsch, K l i n . Woch., 1933, 12, 1276; P. Tateand M. Vincent, Parasit., 1934, 26, 523; E. J. R. MacMahon, Brit. N e d . J.,1934, 477; W. Schulemann, Proc. Roy. SOC. Med., 1932, 25, 897; I n d . Med.Gaz., 1935, 70, 83; W. Kikuth and F. Schonhofer, Miinch. med. Woch., 1935,15, 304; W.Kikuth, Deutsche med. Woch., 1935, 573; C. D. Newman andB. S. Chalam, I n d . Med. Gaz., 1935, 70, 5 ; D. P. Williams and R. Batta-charyya, ibid., p. 8.17 E. Tarejew, Bull. SOC. Path. mot., 1933, 26, 1037; E. Tareer, Med.Parasit. and Parasitic Dis., 1933, 2, 189.18 F. M. Peter, Trans. Roy. SOC. Trop. Hyg., 1935, 29, 41.* In all probability the methylene-bis-salicylate of (XXII) 6-methoxy-S-y-diethylaminopropylaminoquinoline (Fourneau 7 10)422 SIOCHl3MISTRY.possibilities of the beneficial administration of plasmoquin orplasniocide in conjunction with quinine or atebrin.19I. L. Kritschevski and A. I. Pines20 have determined the con-centrations of plasmoquin and plasmocide sufficient, when intro-duced into the Spinus-spinus at the height of infection with Plas-modium pmxox, to destroy the power of the gametocytes to infectthe Culex pipiens.0.J. Magidsoq21 R. Robinson,22 and their respective co-workershave attempted to correlate alterations in the alkoxy-radical andin the length and branching of the dialkylaminoalkyl side chain of6-alkoxy-S-aminoquinoline derivatives of the plasmoquin type withthe variations in antimalarial efficiency which accompany thesechanges in the structure of the molecule, and R. F. A. Altman,23in addition to working along similar lines, has considered changes inthe structure of the natural alkaloid and finds that substitution inthe CH*OH and CHXH groups of quinine destroys its antimalarialpotency.Preliminary reports on atebrin m ~ s o n a t e , ~ ~ a potential improve-ment on atebrin, are promising; I.L. Kritschevski and E. J. Sten-berg 25 describe new derivatives of the plasmoquin type withchemotherapeutic indices greater than that of plasmoquin, buttheir true relative values have still to be established.Serum therapy being as yet only partially successful in the treat-ment of pneumonia-F. Stein 26 has recently reported favourablyon the combined effects of a serum and quinine-C. L. Butler,L. H. Cretcher, and their collaborators 27 have essayed to improveupon optochin (ethylhydrocupreine) 28 and report that hydroxy-l 9 A. E. Eckhardt, Arch. Schiff. Trop. Hyg., 1933, 37, 223; P. F. Russell,Arch. Int. Med., 1934, 53, 309; W. 13. W. Komp and H. C. Clark, Amer. J .Trop.Med., 1935, 15, 131 ; A. Krilow-Drenowsky, Arch. Schiff. Trop. Hyg.,1935, 39,243 ; L. Robin and T. Van-Huan, Bull. SOC. Path. exot., 1935,28, 650.2O Klin. Woch., 1934, 13, 807; 1935, 14, 23; cf. W. Kikuth and F. Schon-hofer, ibid., 1934, 13, 375.21 Arch. Pharm., 1933, 271, 359; 1934, 272,'74; 1935, 273, 320; J . Gem.Chem. Russia, 1934, 4, 1047.22 J., 1929,2959, and subsequent papers; P. Tate and M. Vincent, Para&.,1933, 25, 411.23 Chem. Weekblad, 1935, 32, 345.24 J. R. Blaze and A. T. W. Simeons, Ind. Med. Gaz., 1935, 70, 185; E. P.z 5 2. Microbiol., 1935, 14, 642.28 Munch. med. Woch., 1935, 1434.37 J . Amer. Chem. SOC., 1935, 57, 575, 738, 1083; W. W. G. Maclachlan,H. H. Permar, J. M. Johnston, and J. R. Kenny, Amer. J . Med. Sci., 1934,188, 699.28 R.Morgenroth and co-workers, Klin. Woch., 1911, 48, 1560, 1979; 1914,51, 1829, 1865; Deutsche med. Woch., 1914, 40, 539; Biochem. Z . , 1917, 79,257; H. F. Moore, J . Exper. Med., 1915, 22, 269, 551,Hicks, Rec. Mal. Surv. India, 1935, 5, 203STEWART AND STEWART. 423ethylhydrocupreine affords considerable protection to infected micein doses well below those at which toxic symptoms begin to manifestthemselves. The most recent phase of their work makes contactwith that of T. A. Henry, W. Solomon, and E. M. G i b b ~ , ~ ~ who fromtheir detailed study of the demethylation of quinine and quinidineconclude that Butler's a-apocupreine is identical with apoquinineand that his p-form is a mixture of apoquinine and a new alkaloidof lower rotation.It is rapidly becoming a recognised fact that quinine has definitelyto compete not only with synthetic drugs but also with " totaquina "and like remediesY3O hence the value as standards of reference of thecarefully determined relative efficiencies in bird malaria of purespecimens of the principal cinchona alkal~ids.~lWith physostigmine (eserine) 329 33 the position is much the same,the more simply constituted and less toxic synthetic drug prostigmine(XXIII) 34 rivalling it in efficacy.The investi-gations of M. Reinert and J. A. Aeschlimann34and the pioneer work in this field of E. Sted-man,35 and of E. and (Mrs.) E. S t e d m a ~ ~ , ~ ~ the latterjointly responsible for the introduction of pros-tigmine into medicine.38 Its myotic action is lessmarked, its intestinal action much stronger, than that of physo-stigmine, and in therapeutic doses it lacks the instability and thetoxic properties which detract from the value of the alkaloid.The recent synthesis of dl-eserethole 33 suggests a near approachto the realisation of a cheap synthetic physostigmine, added interestbeing lent to this work by the markedly successful use of physo-stigmine, of prostigmine, apd of the phenylmethylcarbamic esterderivative analogous to prostigmine in cases of myasthenia gravis,3929 J ., 1934, 1923; 1935, 966; Chem. arrd Ind., 1935, 54, 641.3" E. J. Pampana and W. Fletcher, League of Nations Rep., 1934, 3, 325;R. N. Chopra, B. Sen, and S. K. Ganguli, Ind. Med. Guz., 1935, 70, 362.31 T.A. Henry, T. W. Trevan, and co-workers, Biochem. J . , 1934, 426.For a brief ritsum6 see Lancet, 1935, ii, 631, or Nature, 1935,136, 539-0 reportof a chemotherapy discussion a t tho British Association Meeting, Sept. 9th,1935.O*CO*NMe,[CH,],.so,Me T- culminating in the production of m y ~ t i n , ~ ~ are 0(XXIII.)32 Ann. Reports, 1932, 29, 197.33 P. L. Julian and J. Pikl, J . Arner. Chem. SOC., 1933, 55, 2105; 1934,34 J . Pharm. Exp. Ther., 1931, 43, 413.35 Biochem. J., 1926, 20, 719; 1929, 23, 17.37 A. C. White and E. Stedman, J . Pharm. E x p . Ther., 1931, 41, 259.38 E. A. Carmichael, F. R. Fraser, D. McKelvey, and D. P. D. Wilkie,39 M. B. Walker, i b i d . , p. 1200; E. A. €3. Pritchard, ibid., 1935, i, 432.56, 1797; 1935, 57, 539, 563.36 J., 1929, 609.Lancet, 1934, i, 942424 BIOCHEMISTRY.the last-named remedy being effective despite its being the only oneof the three drugs which does not act as an antidote to curarepoisoning, whose symptoms closely resemble those of myastheniagravis.The effect of injections of prostigmine and atropine sulphatecan be observed within five minutes of administration, is markedwithin half an hour, but has unfortunately disappeared after abouteight hours.It is probable that the effective action of physostigmine andother urethanes in myasthenia gravis is due to the inhibiting actionof these substances on the destruction of acetylcholine. I n viewof the auggestion of Loewi and Navratil 4O that such an explanationaccounted for the action of physostigmine on the heart, and thatthe destroying agent was enzymic, E.Stedman and E. Stedman41investigated the effect on liver-esterase of a series of syntheticurethanes known to resemble physostigmine in other physiologicalproperties. They found that these substances, in very low con-centration, markedly inhibited the action of the esterase. Theextension of these results to other esterases, with the demonstrationthat both pancreatic lipase and kidney phosphatase were relativelyunaffected by urethanes,42 was followed by experiments with acetyl-choline as substrate and an attempt to purify the enzyme prepara-tions-experiments which led E. Stedman, E. Stedman, and L. H.Easson 43 to the discovery of a specific “ choline esterase.” Thisenzyme rapidly hydrolysed esters of choline (acetylcholine mostreadily) and had little activity towards methyl butyrate (purifiedpreparations recently obtained, 50-100 times as active towardscholine esters as the original serum, had no detectable activitytowards methyl butyrate 44). Manometric methods for the estim-ation of choline esterase have been described by R.Ammon 45 andby E. Stedman and (Mrs.) E. Stedman.46 It appears that the con-centration of the enzyme in the blood varies considerably in differentspecies, as also does its distribution between plasma and corp~scles.~~It is absent from the cerebro-spinal fluid, but is present in brain,where the concentration in the basal ganglia is about double thatin the cortex (Dikshit 47 has found a similar distribution of acetyl-choline in brain),Choline-esterase is inhibited by physostigmine and similar4O Pflugers Archiu, 1929, 214, 678, 689.4 1 Biochern.J., 1931, 25, 1147; A., 1931, 1190.42 E. Stedman and E. Stedman, ibid., 1932, 26, 1214; A., 1932, 1166.43 Ibid., p. 2056; A., 1933, 315.4 5 Pfl2gem Archiv, 1934, 233, 486; R. Ammon and G. Voss, ibid., 1935,235, 393 ; A., 1279.46 E. Stedman and E. Stedman, Biochem. J., 1935, 29, 2107.47 J . Physiol., 1934, 80, 409.44 Ibid., 1935, 29, 2563POLLARD. 425substituted urethanes to an even greater extent than liver-esterase,and the inhibiting power is proportional to the myotic activity.48A decrease in serum choline-esterase activity has been found byM. S. Jones and H. Tod 49 to follow administration of physostigmine(but not pilocarpine or adrenaline). It is thus reasonable to supposethat the remarkable effect of the urethane drugs in myastheniagravis is related to their action on choline-esterase. The fault inthis condition may, on this supposition, lie either in an excessiveconcentration of the enzyme or in a deficient production of acetyl-choline. Stedman has published figures indicating that inmyasthenia gravis there is at any rate no increase in the bloodcholine-esterase, a result which, though not conclusive, suggeststhat the latter alternative is correct.The year under review has seen an interesting addition to themeans of combating infection of the urinary tract.Within the lastfour years good results in the treatment of urinary infections havebeen obtained by the use of a ketogenic diet,51 i.e., by a diet so poorin carbohydrate as to encourage the excretion of large amounts ofacetoacetic and p-hydroxybutyric acids in a strongly acid urine.The effect was traced t o the bacteriostatic action of p-hydroxy-butyric a ~ i d .5 ~ M. L. Rosenheim 53 found that bacteriostaticpower on the growth of B. coli, in uitro, was possessed by a number ofother organic acids, notably benzoylacetic, p-hydroxypropionic,and lam-ulic. Mandelic acid compared favourably with p-hydroxy-butyric acid, was non-toxic, was excreted unchanged in the urine,and was shown by clinical trial to be effective in cases of urinaryinfection, provided the urine was rendered strongly acid by adminis-tration of ammonium chloride.The claims of Rosenheim as to thetherapeutic value of mandelic acid have been confirmed by D. M.Lyon and D. M. D~nlop.~* c. P. s.J. S.2. PLANT BIOCHEMISTRY.Growth-regulating 8ubstances.The interest in these vital growth factors noted in the previousReport 1 continues steadily to increase. The notable work ofP. Kogl and colleagues on the constitution of auxin-A and -B has4 8 E. Stedman, private communication.40 Biochem. J., 1935, 29,2242; A., 1274.50 E. Stedman, J . Physiol., 1935, 84, 56 1’.5 1 A. L. Clark, Proc. Staff Meetings Mayo Clinic, 1931, 6, 605; H. F.Helmholz, ibid., p. 609.52 A. T. Fuller, Lancet, 1933, i, 855.53 Ibid., 1935, i, 1032; A., 887.1 Ann. Reports, 1934, 31, 358.64 Brit.Med. J . , 1935, ii, 1096.Ibid., p. 216.0 426 RTOCTTEMTSTRY .been followed by the isolation from urine and other sources ofanother substance exhibiting similar growth-stimulating properties,but quite unrelated, chemically, to the auxins. This “ hetero-auxin” 3 is identified as indole-3-acetic acid. It is produced bythe bacterial decomposition of tryptophan, and according to Kogl,may occur in appreciable amounts in urine under conditions inwhich the bacterial population of the intestine becomes abnormal.Although giving positive reactions in Went’s auxin4 test (oatcoleoptile), heteroauxin is conveniently differentiated from theauxins in routine laboratory work by being easily decomposed byacids and by its relative stability towards alkali.Auxin-A isreadily decomposed by alkali, and auxin-B by both acid and alkali.Went’s diffusion test records a molecular weight of approximately175 as compared with approximately 350 for the auxins. On thisbasis the growth substance of coleoptile tips is definitely auxin-A,whereas that obtained from Rhizopus is or includes heteroauxin.Physiological Activity of Growth Substance.-Although Kiigl’swork has given a definite chemical basis to the problem of growthsubstances, the response of plants t o these substances demands, andis receiving, extensive investigation. Subsequently to the workpreviously reported,* R. Snow and B. Le Fanu showed that pureauxin-A and also heteroauxin in concentrations of 1-2 p.p.m. inducestrong cambial growth in strips of tissue from decapitated sunflowerhypocotls.A. Uhrova6 shows the growth-inhibiting substance presentin leaves of Bryophyllum crenatium restricts the development ofaxial buds on that side of a shoot stump to which it is applied.He also confirms that the substance diffuses into the tissues and maysubsequently be detected in the expressed juice and in an etherealextract of the tissue. V. M. Katunski7 records that auxin fromcoleoptile tips of oat and maize not only induces cell elongation instems and checks the formation of adventitious rootlets on cut rootsof Vicia faba, but also inhibits regenerative cell division in cutsurfaces of succulent leaves. The “ wound substance ” appearinga t the cut surfaces of decapitated roots is now assumed by P.Keebleand M. G. Nelson to be auxin-A. The traumatic curvature of theroot is explained by the effect of cutting on the distribution ofauxin-A within it. No geotropic curvature occurs in the rootuntil an adequate amount of auxin-A has been acquired. TheF. Kijgl and D. G. F. R. Kostermans, 2. physiol. Chem., 1934, w$, 90Ann. Reports, 1934, 31, 359.Nature, 1935, 135, 149; A., 418; R. Snow, ibid., p. 876; A., 905.Compt. rend. Acad. Sci. U.S.S.R., 1938, 1, 661; A,, 795.104, 113; A., 1934, 1418.6 Planta, 1934, 22, 441 ; A., 1935, 548.8 Proc. Roy. SOC., 1935, [B], 117, 92; A., 548; cf. New Phytol., 1930,29,289POLLA RD . 427distinction is made between the effects of auxin in promotinggrowth (controlled by concentration) and in inducing curvature,which depends on the gradient of concentrations on oppositesides of the root.Another form of activity of a growth-regulating substance ispostulated by J.P. McColl~rn,~ who ascribes the general retardationof vegetative growth in plants during the development of fruits tothe presence in the fertilised ovary of auxin or a related substance.N. Cholodny lo demonstrates the existence of a growth-substancein the starchy endosperm of maize and other Graminem in the veryearly stages of germination. Its formation is associated withstarch hydrolysis, and probably begins with the onset of enzymeactivity following the first absorption of water by the seeds. It isnot initiated by the germinative process, since it occurs in seedswhich have lost, naturally or artificially, their germinative power.Once formed, the growth substance passes rapidly into the developingembryo.Callus formation on cut epicotls following the application ofgrowth substance from pollen and urine in the form of a lanolinepaste is further examined by F.Laibach and 0. Fischnich,ll whohave now developed a method of determining the activity of auxinpreparations, depending on the rate of thickening of decapitatedepicotls of Vicia faba. Standard curves representing the relation-ship between the percentage increase in’ diameter of the epicotland the concentration of growth substance applied are obtained bymeans of heteroauxin pastes containing 73 x 10-6 g. of P-indolyl-acetic acid per g.of paste. In a subsequent paper l2 the sameauthors record the root-initiating effects of pure heteroauxin.Treatment of intact stems with the paste results in a callus formationat or near the point of application, followed, in a few days, by theappearance of rootlets. Application to the upper side of the mid-rib of a leaf results in relatively greater growth on that side, causinga local thickening of the leaf and a downward curvature. Callusor root formation on the leaf-stalk, if occurring at all under theseconditions, is slight or late in developing. If, however, the under-side of the mid-rib is treated, the leaf-stalk swells, and on the sidesof the stem lying beneath the leaf pair a callus is produced, followedby a line of rootlets. On the other sides of the stem neither callusnor roots appear.With a less concentrated paste, the rootlets areformed more slowly, principally at the upper end near the callus.9 Cornell Uniu. Agric. Exp. Sta. Mem., 1934, NO. 163, 27 pp. ; A., 1934, 1419.lo Planta, 1935, 23, 289; A., 905.12 Ibid., p. 495 ; A., 1038.Ber. deut. bot. Ges., 1935, 53, 469; A., 1039428 BIOCHEMISTRY.When stems are placed horizontally, roots are formed principallyon the under side. From these and numerous other results Laibachsuggests that the root-stimulating substance moves axially withinthe plant tissues, mainly through the large conducting vessels.Transverse movement is probably a much slower process. Hetero-auxin thus appears to possess the cell-elongating influence formerlyattributed to auxin-A, together with a root-initiating power.Whichof these two functions becomes dominant depends on the conditionsof the experiment, the manner of application, and the quantity ofthe growth-substance concerned. Thimann l3 compares the root-forming properties of indole-3-acetic acid with those of the root-hormone previously examined and concludes that the growth-promoting and the root-forming substance are identical. A. T.Czaja 15 differentiates between the action of growth substance ondecapitated stems when applied in the direction of normal movementwithin the plant (axially), and when applied transversely. Theformer leads t o lengthening but no thickening of the stem, thelatter restricts stem growth and induces a widening and possiblyshortening of the cells and thickening of the stem below the point ofapplication.The latter is explained as the result of an antagonismbetween the natural and the induced stream of growth-substancewithin the plant. Positive curvature may be induced by transverseapplication of a concentrated preparation of growth-substanceand is attributed to partial transverse streaming. Czaja holdsthat the primary function of the growth substance is the stimulationof cell elongation but not of division, and that the latter, when itoccurs, is a secondary effect resulting from localised disturbance ofthe polarity of the plant system. The growth substance is assumedto polarise plant cells. According to Laibach (loc. cit.) high con-centrations of growth substance cause positive curvature of stemsthrough cell injury in the treated tissue.From the physiological viewpoint the activities of growth hor-mones appear to have been somewhat clarified, although opinion asto the mechanism of their action is still divided.It is, however,not yet clear, on chemical grounds, why the auxins and hetero-auxin should possess such functional similarities.Possible Constitutional Speci$city of Growth Substances.--It hasbeen anticipated by a number of workers in this field that the activityof these substances might be associated with some particular mole-cular structure or with a specific grouping of atoms within the13 K. V. Thimanri and J. B. Koepfli, Nature, 1935,135, 101; A., 418.14 K. V.Thimann and F. W. Went, Proc. K. Akad. Wetensch. Amsterdam,15 Ber. deut. bot. Ges., 1935, 53, 197, 221, 478; A., 672, 1039,1934, 317, 457; A., 1934, 1418POLLARD. 429molecule. Physiological activity was thought t o be related to theposition of the unsaturated linking. Hydrogenation of auxin-Aleads to complete loss of hormonal activity, as also does esterification.Heteroauxin similarly loses its activity on hydrogenation, butcertain esters and a number of simple derivatives are active, althoughpossessing potencies less than that of the parent substance.Relationships between constitution and growth-regulating propertiesare, however, not yet very clear. For instance, Kogl16 finds thatthe activity of esters of indole-3-acetic acid varies in the orderMe > Et > Pr" > PrP.Among chemically related substancesexamined, Kogl l7 demonstrated the activity of :1 -Methylindole-3-acetic acid (et(hy1 ester inactive).2-Methylindole-3-acetio acid (methyl ester inactive).5 -Met hylind.ole-3- acetic acid (methyl ester active).Indole-3-pyruvic acid.Indole-3- a- propionic acid.Dihydroindole-3-acetic acid.2-Ethylindole-3-acetic acid.2 : 5-Dimethylindole-3-acetic acid.Z- and r-Indole-3-lactic acids.Indole-2- and -3-carboxylic acids.Indole-3 - P-pr opionic acid.On the other hand, the following proved inactive :A. E. Hitchcock18 increased the list of active substances by theaddition of indole-3-n-propionic, phenylacrylic, and phenyl-propionic acids, with the aid of which he induced root-initiation,bending and intumescence of stems, and epinasty of leaves.Although these experiments may riot be dealing with quite thesame phenomena, they recall earlier work of Zimmerman and others19of the same institution, in which exposure of plants to appropriateconcentrations of carbon monoxide checked stem elongation, causedleaf epinasty, and induced the development of axial buds and ofadventitious roots. Similarly 2O#21 ethylene, propylene, butylene,and acetylene were found to cause epinasty in intact or excisedpetioles and by repeated treatmen& produced root formation on16 2.physiol. Chem., 1935, 235, 181, 201; A., 1351.1 7 LOG. cit., also F. Kogl, A. J. Haagen-Smit, and H. Erxleben, ibid., 1934,18 Contr. Boyce Thompson Inst., 1935, 7, 87; A., 795.19 P.W. Zimmerman, W. Crocker, and A. E. Hitchcock, ibid., 1933, 5, 1,20 W. Crocker, P. W. Zirmnerman, and A. E. Hitchcock, ibid., 1932, 4,21 Idem, ibid., 1933, 5, 351; B., 1933, 1027.a$, 90; A., 1934, 1418.195; B., 1933, 726; A., 1933, 437.177; A., 1932, 890430 BIOCHEMISTRY.stems and curvature in roots. Recently F. W. Zimmerman andF. Wilcoxon 22 have shown that CC- and p-naphthyl-, acenaphthyl-5-,phenyl-, fluorenyl-, and anthracyl-acetic acids, indolebutyric acid,and a-naphthylacetonitrile exhibit the general physiologicalactivities of growth substances. The close similarity between theeffects of ethylene and of growth substances on plants is discussed ina further paper 23 in which the significance of observations of theemanation of gas resembling ethylene from certain plant tissues 24is emphasised.In this connection the action of growth substancesin increasing these emanations from treated plants (Zimmermanand Wilcoxon, Zoc. cit.) is worthy of note.Such investigations widen our conception of growth-regulatingsubstances to an almost bewildering extent. The hitherto popularbelief in specific regulatory action becomes increasingly difficultt o maintain. On the other hand, it may be questioned whether theso-called growth substances are really the active agents, or whether,within the plant system, they may give rise to other regulatoryagents, not yet isolated, among which the anticipated specificitymay yet be established. The work of the Boyce Thompson Instituteseems to point to ethylene as being likely to be concerned in thisrespect.The experimental difficulty of subjecting plants to theaction of ethylene under conditions comparable with that of thevarious growth substances has been pointed out, and tends toretard the elucidation of closer relationships.Growth Substances and the Lower Organisms.-Continuing hisearlier W. H. Schopfer now shows 26 that the thermostableauxin-like factor isolated from wheat gerrn,z7 rice polishings,28urine,29 and flower stamens,30 which promotes vegetative growthand zygote formation in Phycomyces, may be synthesised by theorganism itself, provided that vitamin-B1 is supplied in the nutrient .31That the growth factor itself is not vitamin-B, is shown by itsability to activate yeast and its relative insolubility in chl0roform.~2This auxogenic action of vitamin-& is apparently favoured by agenerous supply of nitrogen in the nutrient medium and is mostContr.Boyce Thompson Inst., 1935, 7, 209.23 W. Crocker, A. E. Hitchcock, and P. W. Zimrnerman, ibz'd., p. 231.24 F. E. Denny and L. P. Miller, ibid., p. 97; A., 1179.26 Ann. Reports, 1934, 31, 366.26 Compt. rend., 1934, 199, 1656; A., 1935, 156.27 Arch. Sci. phys. nut., 1934, [v], 16, Suppl., 47, 165; A,, 1935, 663.28 Arch. Mikrobiol., 1934, 5, 502, 511; A., 1935, 534.2B Arch. Sci. phys. nat., 1934, [v], 16, Suppl., 200; A., 1935, 786.30 lbid., p. 169; A., 1935, 663.31 Compt. rend., 1935, 200, 1965; A., 1027.a2 Arch. Sci. phys. nut., 1935, [v], 17, Suppl., 56; A., 1289BOLLARD.43 1marked a t pH 7-0-7.2.33 Synthesis of growth substance by theauxoheterotrophic Phycomyces in vitamin-free media may beinitiated by inoculation with extracts of cultures grown on activemedia, or with cultures of auxoautrotrophic organisms, e.g., Mucor-inece, on vitamin-free media. Both sources can also stimulateyeast cultures.3* Spores of Phycomyces apparently contain sufficientof the growth factor for germination, but external activation isnecessary for further development .35Further examination of the growth substance of yeast is recordedby R. J. Williams and D. H. Sa~nders.~6 A more highly purifiedpreparation of pantothenic acid 37 is obtained and its activityshown to be intensified by the presence of bios I (inositol), and ofvitamin-Bl, minute amounts of the latter producing very markedeffects.Pantothenic acid is regarded as the principal constituentof bios. It appears also to be closely related to “ biotin,” isolatedfrom bios I1 from yeast and from cgg yolk by Kogl.% Biotin isregarded in some quarters as the active agent stimulating celldivision. A. J. Salle and R. W. Dunn 39 describe a growth factor,isolated from rice bran, which stimulates growth and the productionof acid and gas from carbohydrates by a number of species ofbacteria. Organisms which do not ferment carbohydrates areunaffected in any way by this factor, which is probably pantothenicacid. Nodule organisms also contain pantothenic acid, whichappears to pass from the bacteria into the host plant, the growth ofwhich is also influenced.The acid does not affect the actual fixationof nitrogen directly, but is an important secondary factor as aresult of its action on carbohydrate anabolism.40 That the activeprinciple of bios is freely distributed in the animal world and isparticularly concentrated in the kidneys and in tumour growthsis shown by C. Dittmar.*lHardiness and Drought Resistance in Plants.The ohemical and physical changes occurring during the freezingof plant tissue have formed the subject of considerable enquiry inArch. Mikrobiol., 1934, 5, 502, 511; A., 1935, 534.34 Ibid., 1935, 6, 196; A., 1167.35 Ber. deut. bot. Ges., 1935, 53, 466; A., 1039.36 Biochem. J., 1934, 28, 1887; A., 1935, 124.37 Ann.Reports, 1934, 31, 365.38 Ber., 1935, 68, [A], 16; A., 418.39 Proc. SOC. Exp. Biol. Med., 1934, 32, 168; 1935, 32, 939; A., 1935, 408,40 C. H. McBurney, W. B. Bollen, and R. J. Williams, Proc. Nat. Acnd. Sci.,4 1 Biochem. Z., 1935, 279, 99; A., 1165.1419.1935, 21, 301 ; A., 1167432 BIOCHEMISTRY.recent years, more especially since it has been recognised that thepart played by manurial treatment in modifying the frost resistanceof plants is a very definite one. Among others, F. Schaffnit andA. F. Wilhelm,42 working with stored potatoes, tomatoes, andvarious cereal crops, confirm a number of earlier observations thatgenerous manuring with potassium salts increases cold resistanceand further demonstrates that growth in nitrogen- or phosphate-deficient soils produces a somewhat similar effect.Possiblecorrelation between frost resistance and the concentration of cellsaps is also examined. Although the sugar content of saps tendsgenerally to be high in more resistant samples, no definite relation-ship is apparent. Neither the reaction of the sap, its dry mattercontent, nor its osmotic pressure seems to be an influential factor inthis respect. It is also shown that freezing for a short time at avery low temperature produces effects different from those resultingfrom exposure to milder freezing for a longer time. Similar resultsare recorded by A. Anderson and T. A. KiesselbachY43 with thefurther observation that in wheat plants the rates of fall and ofsubsequent rise in temperature contribute materially to the severityof the injury produced.In a later publication Wilhelm,44 usingrape and spinach plants, and following up earlier indications thatcell protein was the seat of cold injury, compared the protein contentof plants in relation to hardiness, but failed to establish that thetwo factors were interdependent. The freezing of plant proteins isshown by Tadokoro and Joshimura45 to result in an increase inamino- and amide-nitrogen, histidine and arginine, and a decrease intyrosine fractions. Wilhelm (Zoc. cit.) indicates, however, that noparallelism exists between protein breakdown and frost resistance.It is suggested that the effects of manuring on hardiness appearmore likely to be related t o variations induced in the phosphatidecontent. The favourable effect of potash manuring is attributed inpart to its action in increasing sap concentration and in part to amore specific effect on the physical condition of the cell colloids.It is further recorded that the decline in sugar content duringexposure to cold is slower in nitrogen- and potassium-deficientplants than in those more adequately nourished.A possibleprotective action of sugar against injury to cell contents is indicated.In this connection the observation of K. Boning and E. Boning-Seubert 46 that deficient salt nutrition tends to lower the sugar42 Phytopath. Z., 1933, 25, 266; B., 1933, 643.Q3 J. Amer. SOC. Agrort., 1934, 26, 44; B., 1934, 418.44 Phytopath. Z., 1935, 8, 111; B., 1061.4 6 J.Fac. Agric. Sapporo, 1928, 25 (cited by Wilhelm).4 6 Biochem. Z., 1934, 270, 122; A., 1935, 708content of plants is significant. The influence of sugar on frostresistance has also been investigatod by Newton and colleague^,^^who show that freezing (at - 7") of the expressed juice of un-hardened wheat plants results in the precipitation of proteins, theextent of which is lowered by additions of sucrose or glucose inamounts up t o 8% of the juice. The " salting-out " of proteinsand their coagulation by acids or bases are also restricted by thepresence of sucrose. On the other hand, removal of electrolytesfrom the juice (by dialysis) increases the amount of protein precipit-ated by freezing. In a subsequent publication48 these effects areshown to be accompanied by an increase in amino-nitrogen and inthe sensitivity of the protein to hydrolysis by alkali.Again thechanges are lessened by additions of sugar. The opinion is expressedthat protein degradation in hardened plants is due to frost actionand is not a protective adaptation.If sugar is to be regarded as a protective agent against injury bycold, the respiratory exchange at low temperatures, in so far as itaffects sugar contents, might be expected to show some relation-ship to hardiness. On this point R. Newton and J. A. Anderson 49report that the respiration rates of spring and winter wheats in thepre-hardened condition are identical. As hardening proceeds,however, the rates decline, those of the hardier winter varietiesreaching a lower level than those of spring types.The catalaseactivity of wheat leaves, examined in autumn, is found t o be closelyrelated to the winter hardiness of different varieties.50 In the courseof a general investigation of this subject S. T. Dexter 51 reports thatthe respiration rates of wheat and cabbage seedlings stored at 2"decrease continuously irrespective of their relative hardiness or theextent of the increase in their sugisr contents. The oxidase activityof plants is not affected at this temperature. Catalase activity incabbage is also unchanged whether plants are hardened in light or indarkness, Under both conditions the degree of hardening is con-siderable. The catalase of the wheat plants at 2" increases in dark-ness but decreases in light.It is concluded that neither respiratoryrates nor enzymic activity can be directly associated with thehardening process. Dexter 52 also confirms that, whereas cabbageand winter cereals having low nitrogen and high carbohydrate4 7 R. Newton and W. R. Brown, Canadian J . Res., 1931, 5, 87; A., 1931,1198.48 R. Newton, W. R. Brown, and J. A. Anderson, ibid., p. 327; A., 1931,1465.49 Ibid., p. 337; A., 1931, 1465.50 R. Newton and W. R. Brown, ibid., p. 333; A., 1931, 1465.51 Plant Physiol., 1934, 9, 831 ; A., 1935, 263,63 Ibid,, 1935, 10, 149; A., 904434 BIOCHEMISTRY.contents harden satisfactorily at 2", high-nitrogen wheat fails to doso a t this temperature. He also shows that increases in solublenitrogen in the plants follow low-temperature storage whetlherhardening occurs or not.Thus, while there is a general associationbetween hardiness, low respiration rates, high sugar content, andincreased soluble nitrogen, it cannot be said that the last-namedthree factors, individually or collectively, are essential character-istics of hardiness.The balance of " free " and " bound " water in plant colloidalsystems has, from time to time, been suggested as a basis for theconsideration of frost resistance. Using calorimetric methods fordetermining the extent of ice formation in plant tissues, Dexterhas re-examined the problem from this point of view. Repeatedfreezing and thawing (at intervals) of crowns of wheat plants showsthat water separated from the colloids as ice during freezing is notcompletely reabsorbed on subsequent thawing, i.e., the process isnot completely reversible.A repetition of the freezing processresults in the formation of a larger amount of ice. As the plantsharden in the field, the difference between the amounts of unfrozenwater at the first and second and subsequent freezings steadilydeclines. There is, therefore, a steady approach to completereversibility of ice formation with increasing hardiness. Theproportion of bound (unfrozen) water in the plant tissue falls as thetemperature of freezing is lowered, presumably as the result of the" freeing " of bound water. The proportion of unfrozen water inhardy varieties is greater than that in more tender plants.On theother hand, the amount of unfrozen water per gram of dry mattera t the first freezing (- 7") is higher in unhardened plants, butdifferences between hardened and tender plants in this respectpractically disappear a t a second freezing. It is implied that,although hardening does not definitely increase the hydration ofplant colloids, the condition of hydration is made a more stable one.As the hardening of wheat plants proceeds, there is a steadydecrease in the amount of extractable electrolytes in the crown androot tissues, and in the concentration of salts in the unfrozen water,values for hardier varieties being somewhat lower throughout.This observation falls into line with the influence of manuring onhardiness in so far as low levels of nutrition induce low soluble-saltconcentrations in the plants.It is also significant that nitrogen-deficient plants exposed to low temperatures in darkness showed thecharacteristic decrease in electrolyte content and became hardened,but high-nitrogen plants under the same condition neither hardenednor showed a loss of soluble salt content. Conditions in lucerne63 Plant Physiol., 1934, 9, 601 ; 1936, 10, 403 ; A., 1935, 266, 1288POLLARD. 435roots appear to be somewhat different. For example, the per-centage of dry matter does not increase during exposure to cold andthere is no decrease in the soluble electrolyte content. Neverthelessthe salt concentration of the unfrozen water in hardened plants isless than that of unhardened controls, although the difference isless definite than in the case of wheat.This is perhaps to beassociated with the fact that a much greater degree of hardness( L e . , resistance to lower temperatures) is attainable in wheat thanin lucerne. H. M. Tysdal,54 in an examination of lucerne, recordsthat diastatic activity of leaves is unrelated to hardiness, but thatroots of the hardier varieties are enabled to accumulate relativelymore sugar in the autumn. An examination of wheat leavesfollowing low-temperature exposure reveals 55 a general increase inthe osmotic pressure and in the total dry matter and sugar contentsof the sap. Differences in these values for varieties of differenthardiness are, however, small. Although the general trend inimportant changes during hardening may be indicated by the leaves,comparison with Dexter’s work suggests that the elucidation ofthe chemistry of frost resistance is to be sought in the crown androot system.Much less detailed attention has been given to the problem ofdrought resistance, but there is evidence that here again the boundwater of the plant system is a vital factor.R. Newton and W. M.Martin 56 have established a cryoscopic method for determiningthe bound water in colloidal systems by the aid of which they showthat in wheat and in grasses the bound water content of the expressedsap of leaves is a satisfactory measure of the adaptability of theplants to drought conditions. That drought resistance may beinfluenced by manuring is indicated by N.L. Udolskaja,57 whorecords that treatment of black-earth soils with sodium phosphatein conjunction with calcium nitrate increases the water-retainingcapacity of certain plants and permits a suitable, though reduced,water balance to be maintained during the dry season. The bene-ficial effects of phosphate manuring in this respect are also reportedby Antonov et aZ.58 and by S. P. Molchanov and A. A. Shirshov,59who find that, although chemical fertilisers do not affect the generalcourse of water-evaporation curves of plants and that potassium54 J . Agric. Res., 1934, 48, 219; B., 1935, 644.65 E. Constantinescu, Planta, 1933, 21, 304; A., 1934, 464.56 Canadian J . Res., 1930, 3, 336; A., 1931, 534.5 7 Compt. rend. Acad. Sci. U.S.S.R., 1934, 2, 45; A., 1935, 821.6 8 L.I. Antonov, K. A. Kaltschevski, A. M. Ruguzov, K. N. Faktulin, andT. G. Katarian, North Caucasian Grain Inst. Coll. Sci. Papers, 1933, No. 1,112; B., 1935, 37.59 Chem. Social Agric., 1932, 1, No. I, 82; B., 1935, 215436 :BIOCIIEMfSTRY.salts do not afford any protection against drought, nitrogenous andphosphatic fertilisers tend to lower the water consumption perunit of dry matter produced by the plants. R. F. Williams6Oconfirms the effect of moderate supplies of phosphates on transpir-ation ratios, but shows that the action of phosphate is a limited one.Carbohydrate changes are also concerned in the conditioningof plants to resist drought. Drought-hardening may be effected bymaintaining plants with a lowered water supply until the leaf tipsbegin to die back.During this period I. M. Vassiliev and N. G.Vassilieva 61 observe a steady increase in the monosaccharide, avariable change in the sucrose, and, after a preliminary fall, a con-siderable and sustained rise in hemicellulose content. Subsequentwatering of the treated plants results in a delayed increase in thesucrose content to values which ultimately exceed those in untreatedcontrols. Plants thus conditioned have a permanently loweredwater content. It is also recorded 62 that drought resistance maybe increased by soaking partly germinated seeds in twice-molarsolutions of sugars for 6 days.Thus, while much yet remains to be investigated, it would appearthat the water relationships of plant colloids are a dominant factorin both frost- and drought-resistance.Carbohydrate materialsrepresent important agents protecting the colloidal system fromphysical denaturation and probably also, in the case of frost resist-ance, from chemical decomposition in which protein constituentsare largely concerned.Plant Nutrients.Nitrogen.-A considerable proportion of a wide literature con-cerning plant nutrition is occupied with the question of nitrogen.In a number of papers dealing with the complex problem of thecomparative values of nitrates and ammonium salts for this purpose,the influence of the level of supply of other nutrient materialsreceives rather more prominence this year. The utilisation ofammonium salts by the cotton plant under acid conditions isshown by V.S. Ivanova 63 to be favoured by the presence of calciumchloride or sulphate but adversely affected by that of magnesiumchloride or sulphate. Salts of potassium do not affect the intake ofeither ammonia or nitrates under acid conditions but increasethat of nitrate from neutral media. In spite of the influence ofthese other nutrient materials the relative assimilation of the two6o Austral. J . Exp. Biol., 1935, 13, 49; A., 795.61 Bull. Acad. Sci. U.S.S.R., 1934, 1340; A., 1935, 796.62 M. T. Timofeeva, Plant I d . U.S.S.R., 1933, A., No. 7, 69; A., 1935,63 Lenin Acad. Agric. Sci. Ged. In&. Bert., 1934, No. 3, 77; B., 1935, 918.1045POLLARD. 437forms of nitrogen still appears to depend mainly on the reaction ofthe substrate.As a complementary observation to the above maybe cited the restriction of the intake of potassium in the presenceof sodium nitrate.64 According to I. G. Dikusar 65 the beneficialeffect of ammonium chloride on the growth of flax in sand culturesis increased by raising the concentration of calcium and magnesiumin the nutrient. In agreement with Ivanova's observations (above)a high proportion of magnesium without adequate amounts ofcalcium is shown to produce adverse effects. Ammonium-nutritiontends to lower the base (notably K) and increase the phosphatecontents of plants, whereas nitrates have the opposite effect.Working with sugar beet, A. V. Vladimirov 66 compares the influenceof chlorides and of sulphates on the utilisation of nitrogen in sandcultures.With nitrogen supplied as ammonium salts, chloridesproduce the higher yield of beet, but with nitrates the best resultsare obtained by use of sulphate-containing nutrients. With increas-ing concentrations of ammonium salts in media having pH 4.5 and6-5 there is a steady rise in the nitrogen content of the crop whethersulphate- or chloride-nutrients are used. The effect is reversed inmedia having pH 8.2. The soluble-nitrogen content of the beet isincreased by potassium chloride but lowered by the sulphate. Byraising the level of supply of potassium in either form, the totalnitrogen and sugar content of the plants is increased in nutrientsof pH 4.5 and 8.2 but unaffected by those having pH 6.5. The per-centage of sugar in beet from nitrate media is higher when sulphatesthan when chlorides are given.At all p , levels potassium saltsincrease the chlorophyll content of leaves of plants grown in ammon-ium-media. The individual effects of differences of reaction andof the composition of other solutes present tend in general to besuperimposable. Another instance of this generalisation is affordedby S. F. Trelease and H. M. Trelease,67 who show that the growth ofplants tends to lower the pH of nutrient solutions in which theNO, : NH, ratio is low and to increase the p , when the ratio ishigh. Suitable adjustment of the ratio forms the basis of a method,devised by these authors, for preparing media which, in use, retainthe initial pH for a number of dayse68Potassium-Further evidence is recorded of the comprehensivecharacter of the various effects of potassium in the intake and64 J.Mikulowski-Pomorski arid J. Salcewicz, Rocz. Nauk. roln. lein., 1934,6 5 Lenin Acad. Agric. Sci. Ged. Inst. Pert., 1934, No. 3, 67; A., 1935, 1178.6 6 Ibid., 1934, No. 3, 104; B., 1935, 868.6 7 Amer. J . Bot., 1935, 22, 520; A., 1178.6 8 Science, 1933, 78, 438; A., 1934, 120.31, 116; B., 1935, 966438 BIOCHEMISTRY.utilisation of other nutrients. I n connection with the manuringof cereals it is shown that potassium sulphate increases the total-and phytin-phosphorus and protein content of wheat, although inthe matured plants the amount of potassium in the tissues is notgreatly affected.69 The reciprocal effects of potassium and nitrogenon the assimilation, transpiration, and chlorophyll content of ryeare examined by G.Gassner and G. Goeze.70 Maximum assimilationoccurs with moderate nitrogen supplies and small proportions ofpotassium, or with excessive nitrogen and high potassium supplies.With adequate amounts of potassium, increasing supplies of nitrogenincrease assimilation and transpiration, whereas in potassiumdeficiency t,he reverse occurs. Under both sets of conditions thechlorophyll content of the plants is increased. According to G.Rohde 7l the action of potassium in increasing zrobic and retardingarmrobic respiration in plants is related to its ability t o improvethe distribution of iron within the system. I n tomato plantsinsufficiency of potassium lowers the ash content of the dry matterand increases the proportion of calcium, magnesium, and phosphorustherein.V2 The question of the possible replacement of potassiumby other bases in respect of its function within the plant continuesto be a subject of investigation.A. G. McCalla 73 provides furtherconfirmation that in the wheat plant potassium deficiency may bepartly counteracted by a suitable supply of sodium. M. Korczewskiand F. Majewski7* indicate that the sodium requirement of oatsin relation to dry matter production varies considerably withthe season, values ranging from 22 to 74% of the requirement ofpotassium. Although the growth of plants is greatly influencedby the supply of sodium, the amount remaining in the plant atmaturity is very small, none occurring in leaves.A number ofattempts to discover whether rubidium, czsium, or lithium canplay the part of potassium in the plant system have in practicallyall cases shown negative results.75 Rubidium is taken up byplants and tends to modify mineral metabolism. Only in oneinstance is it shown that potassium can be partially replaced by69 L. Marimpietri, Ann. R. Staz. Chim. Agrar. Sperim., 1934, 14, No. 313;B., 1935, 73.70 2. PJlanz. Diing., 1934, A, 36, 61; B., 1935, 72.71 Ibid., 1935, 39, 159; A., 1178.72 T. G. Phillips, T. 0. Smith, and R . B. Dearborn, New Hamps. Agric.Exp. Xta. Tech. Bull., 1934, No. 59 ; A., 1935, 553.73 Canadian J . Res., 1934, 11, 687; B., 1935, 244.74 Rocz. Nauk. roln. kin., 1934, 31, 22, 141; B., 1935, 966, 967.75 W.E. Brenchley, Ann. Appl. Biol., 1934, 21, 398; A., 1934, 1274; F.Alten and R. Gottwick, Emtihr. Pflanze, 1933, 29, 393; B., 1934, 33; K.Heller, K. Peh, and F. Giirtler, 2. Pflanz. Diing., 1934, [ A ] , 35, 215; B., 1935,11 13POLLARD. 439rubidium, vuiz., in the marine diatom Witxschia cZo~terium.7~ K.Scharrer and W. Schropp 77 record stimulative effects of smallconcentrations ol lithium, but there is no evidence that the actionof the base bears any resemblance to that of potassium.Xecondary Nutrients.-A number of workers record beneficialeffects on plant growth of mixtures of the secondary or “ micro ”-nutrients added to water-culture media, in comparison with those inwhich highly purified salts have been used to provide the majornutrients. The elements commonly shown to exert secondaryeffects include copper, aluminium, manganese, zinc, boron, fluorine,and iodine.In the case of flax, A. P. Schtscherbakov 78 shows thatsuch a mixture of nutrients not only increased the total growth, butcaused greater chlorophyll accumulation, increased the percentageof calcium and magnesium in the dry matter of leaves, and decreasedthat in the stems. Differences in the distribution of mineral matter,notably calcium and magnesium, in the plant due to the presence ofthe “ micro-”elements are attributed to differences in the form ofcombination in the tissues. Organic compounds predominate inthe presence, and inorganic compounds in the absence, of theseelements.R. S. Young,79 working on somewhat similar lines andusing green alge as test plants, reports that no relationships areapparent between the toxic or stimulative action of a number ofthe rarer elements in soils and the oxidation-reduction potentialof the growth media.Among more detailed examinations of the individual elementsmay be cited those dealing with the function of manganese in plantgrowth. In certain Conij’erm, N. C. Nag80 observes a markedincrease in manganese content during the formation of the femaleflowers. Cones also have a relatively large proportion of manganese.K. Scharrer and W. Schropp g1 show that, in sand cultures of cereals,replacement of the customary amounts of iron in the media bymanganese (up to 50%) tends to increase root production a t theexpense of shoot growth.Complete replacement prevents growth.The intake of manganese by wheat seedlings is apparently influencedto a large extent by the nature of the anions present, as well as bythe reaction of the medium.g2Interdependence of the copper and iron functions in plants is7 6 F. A. Stanbury, J . Marine Biol. ASSOC., 1934,19, 931 ; A., 1934, 821.7 7 Erniihr. PJEanze, 1933, 29, 413; B., 1934, 417.7 8 2. Planz. Dung., 1935, 39, 129; A., 1179.79 Gornell Univ. Agric. Exp. Sta. Mem., 1935, No. 174; B., 1109.So Trans. Bose Res. Inst., 1932-1933, 8, 179; A., 1935, 266.81 2. PJEanz. Dung., 1934, A , 36, 1 ; B., 1935, 73.82 J. Davidson, Proc. 2nd Internat. Congr. Soil Sci., 1933, 2, 84; A., 1934,337440 'RTOCHEMTSTRY .indicatcd by L.G. Willis and J. R. Pilar1d,8~ who record thataccumulations of iron in maize plants grown under certain conditionsand formerly ascribed to deficiency of potassium, may be correctedand the crop yield increased by application of copper sulphate tothe soil. Further,84 in orange trees suffering from a form of chloro-phyll deficiency, treatment with copper salts produced a markedincrease in chlorophyll production, although no copper actuallyaccumulated in the leaves.The ill effects of boron deficiency on growth and disease in plantshave been sufficiently emphasised in recent years to render thetreatment of soil with boron compounds a matter of practicalagricultural interest. The action of borax and boric acid on dry rotor heart rot in sugar beet figures prominently in this connection.Whether boron deficiency is the direct cause of the disease or is acontributory factor increasing susceptibility to external attack, isstill debated in some quarters.The present trend is towards theview that heart rot is a boron-deficiency disease and not a microbialinfe~tion.8~ G. Wimmer and H. Ludeckeg6 indicate that soilapplications of boric acid may improve crop yields and sugar returnswithout decreasing liability to dry rot. The incidence of thedisease is decreased by any condition which retards leaf growth.Assimilation of boron by plants appears to be heavily restricted bysoil alkalinity,s7 and it is in these conditions that heart rot is par-ticularly severe.88 Boron is also shown to stimulate the germinationof pollen grains,@ to correct the toxic action of heavy metals,e.g., of excessive amounts of iron,g0 and in some cases to influencethe level of nitrogen intake by p l a n t ~ .~ lThe action of zinc in preventing or correcting certain diseasedconditions in plants has been noted in a number of papers, e.g., incorrecting " bronzing " in tung trees 92 and " white bud " in maize.9383 Soil Sci., 1934, 37, 79; B., 1934, 373.84 0. S. Orth, G. C. Wickwire, and W. E. Burge, Science, 1934, 79, 33; A.,85 W. Hughes and P. A. Murphy, Nature, 1935,135,395; B., 374.86 2. Ver. deut. Zucker-Id., 1934, 84, 627; B., 1935, 38.87 G. A. Talibi, 2. PJlanz. Dung., 1935, 39, 257; B., 867; M. A. Belousov,Arb, Chem. Sektors U.S.S.R., 2, 20; B., 690.88 E.Foex and H. Burgevin, Compt. rend. Acad. Agric. France, 1934, 20,978; B., 1935, 472.8g T. Schmucker, Planta, 1934, 23, 264; A., 1935, 552.90 W. E. Loomis and J. J. Wilson, Proc. Iowa Acad. Sci., 1933, 40, 53; B.,91 F. Terlikowski and K. Milkowski, Rocz. Naub. roln. Zek., 1934, 31, 167;92 H. Mowry and A. F. Camp, Florida Agric. Exp. Sta. Bull., 1934, No. 273 ;1934, 334.1935, 1011.B., 1935, 967.B., 1935, 603.R. M. Barnette and J. D. Warner, Soil Sci., 1935,39,145; B., 742POLLBRD. 441J. Dufrenoy and H. S. Reed 94 conclude that zinc and iron have aspecific effect on assimilation processes. This may be related tothe observation of T. Thunberg 95 that zinc (and also cadmium)influences oxidation-reduction processes in plant materials.Biochemistry of Moulds.In the period elapsing since the last reference to this subject inthese Reports a very considerable amount of research has beenrecorded.Although no spectacular achievements have appeared,the steady advance in our knowledge of the nutrition and metabolismof the moulds necessitates notice here.Mineral Nutrition.-The intake of bases by A . niger is examinedby E. Rennerfelt,96 who shows that the course of intake of mineralsdepends not only on the permeability of the tissues and on the actualand relative concentrations of the different ions in the substrate,but also on the capacity of the cells to accumulate individual ions.Under normal conditions spores contain larger amounts of cationsthan does the mycelium.The ease of intake is in the general orderK' > Mg" > Na'. Antagonistic effects are shown by both calciumand magnesium in respect of pot,assium. According to E. I.S o t n i k ~ v , ~ ~ magnesium appears to have a specific effect in increasingthe growth and citric acid production of A . niger, but this effect isobserved only when the base is supplied as nitrate. RossiY9* on theother hand, regards magnesium supplied as sulphate as having afavourable influence on, without being essential to, the growth ofthe mould. In another paperyg9 the same author records magnesiumsulphate in certain media as actually causing a decrease in drymatter production. Certain moulds appear to be highly sensitiveto injury by magnesium, and it is notable that in a number of suchcases the addition of calcium salts to the nutrient counteractsmagnesium t0xicity.l Strontium can, at least in part, replacecalcium in this effect, which is attributed to the influence of thebases on colloidal phenomena in the tissue.Apart from its nutrientfunction, calcium can also influence the growth of A . niger byactivating the utilisation of carbohydrates in potassium-deficientmedia.2 C. Pontillon also shows that potassium may be partiallyQ4 Ann. agron., 1934, 4, 637; A., 1935, 266.95 Skand. Arch. Physiol., 1934, 69, 247; A., 1935, 1038.g6 Planta, 1934, 22, 221; A., 1934, 1139.Q7 Compt. rend. Acad. Sci. U.S.S.R., 1934, 3, 273, 279; A., 1934, 1263.9 8 G. Rossi and G. Scandellari, Biochirn.Terap. sperim., 19, 92; A., 1934,99 Idem, Atti Congr. naz. Chim., 1933,4,795; A., 1934, 1263.1405.1 U. Stoess, Diss., Gottingen, 1932; A., 1935, 535.3 Ibid., 1936, 119, 349; A., 1027.C. Pontillon, Conapt. rend. SOC. Biol., 1934,117, 647 ; A., 1935, 255442 BIOCHElkIlSTRY.replaced by sodium or magnesium in its physiological activitywithin the fungal system. The ill effects of inadequate suppliesof potassium on the carbohydrate metabolism of A . niger areaccompanied by an accumulation of ammonia in the mycelium andthe appearance of considerable amounts of oxalic acid in thesnbstrate.4The effects of the so-called " secondary " nutrients continue toreceive attention. The essential character of zinc for the growth ofA . niger, recognised for some years, is further investigated byG.L~hmann,~ who makes quantitative measurements of relationshipsbetween dry matter yields and the concentration of zinc in thenutrient. Zinc-growth curves thus obtained have much in commonwith those for nitrogen and phosphate. The toxicity of relativelyhigh concentrations of zinc is dependent partly on the actual con-centration and partly on the nature and relative proportions ofother substances in the medium. The action of zinc on the growthof the fungus is paralleled by that on the invertase activity, althoughthe optimum zinc concentrations for the two functions are not thesame. The maximum accumulation of citric and gluconic acids byA . niger is associated with specific concentrations of zinc sulphate,which vary somewhat according to the particular strain used.Itis shown that zinc influences the respiratory activity of the organismand its ability to utilise sugar.6 Observations of V. S. Butkevitschand S. A. Barinova' show that in the large-scale manufacture ofcitric acid by A . niger yields are increased by additions of zinc saltstlo media used for inoculatlion cultures, but not by direct admixturewith the sugar mash.The influence of iron and other nutrients on acid production bymoulds is considered in the section dealing with acids. Extensiveconsideration of the requirements of A . niger in respect of iron,zinc, copper, and manganese is given by R. A. Steinberg,* andI<. Pirschle presents a systematic examination of the effects ofa wide range of nutrient and other inorganic acids and bases on thegrowth and sporulation of this organism.Nitrogen N u t r i t w n of Moulds.-Many recent investigations of theinfluence of various sources of nitrogen on the growth and metabolismof moulds deal with comparisons of nitrates and ammonium salts forthis purpose, and the close relationship between carbon and nitrogen4 A.Rippel, Arch. Mikrobiol., 1934, 5, 561; A., 1935, 535.5 Ibid., p. 31; A., 1934, 697.6 G. Vassiliev, Biochem. Z., 1935, 278, 226; A., 1027.7 Schr. zentr. biochem. Porschungsinst. Nahr. Cfenussm., MOSCOW, 1932, 2,163; B., 1934, 118.Bull. Torrey Bot. Club, 1935, 62, 81; A., 1166.9 Planta, 1934, 23 177; A., 1935, 535metabolism is frequently emphasised.For instance, H. Hkrdtl loshows that during the most active growth period of A . niger, thesteady increase in the absolute nitrogen content of the culture isaccompanied by a decline in the percentage of nitrogen, the relativechanges being dependent on the proportions of carbon and nitrogensupplied. Increasing amounts of sugar in the nutrient accelerategrowth and intensify respiratory activity. Appreciable formation ofcitric acid, however, occurs only with low levels of supply of nitrogen.As a result, in high-nitrogen cultures, acid production is delayeduntil the nitrogen source has been largely utilised. The compositionof cultures of several species of Aspergillus on ammonium- andnitrate-media is recorded by S. Yamagata.11 Usually the carbonand hydrogen contents vary but little, but that of nitrogen ismarkedly influenced by the nature of the source of nitrogen and bythe relative proportions of carbon and nitrogen in the nutrient, alow C : N ratio being associated with high nitrogen content in theculture.Ammonium-nutrients lead to higher proportions ofnitrogen in the organism than do ni trate-nutrients, irrespective ofthe source of carbon. The respiratory quotient of ,4. o r y m varieswith the nature of the nitrogen supply in the order, nitrate >nitrite > ammonium salts, the order being preserved with all thecarbon sources examined. D. Bach and D. Desbordes l2 record thatin acid glucose media A. repens reduces nitrates quantitatively toammonia, which appears in the substrate, no increase in dry matterproduction taking place.This action reaches a maximum atpH 4-4-54. In more alkaline media (pH > 6.6) nitrate reduction isstill high, but exosmosis of ammonia ceases and growth proceedsnormally. The initial stage of the utilisation of nitrites by a numberof mould species appears to be the production of ammonia (butnever of nitrate) even in neutral or alkaline media.13 Relationshipsbetween carbon and nitrogen metabolism and the reaction of themedium, in the case of Fusarium Zycopersici and F . Zini, are examinedby G. Luz.14 With ammonium nitrate as source of nitrogen, thefirst stage of growth in media having pH 3-9 is marked by the produc-tion of organic acids and a corresponding decrease in pH. Sub-sequently there is a period of preferential intake of nitrate and asteady increase in pH to 7.5.At this point, utilisation of ammoniabecomes dominant. With the exhaustion of the sugar supply,10 Biochem. Z., 1934, 268, 104; A., 1934, 452.11 Acto Phytochim., 1934, 8, 107, 117; A., 1934, 1262.12 Compt. rend., 1933, 197, 1463, 1772; A., 1934, 112, 220.13 K. Sakaguehi and W. Y . Chang, J . Agric. Chem. SOC. Japan, 1934, 10,l4 Phytopath. Z., 1934, 7, 585; A., 1935, 538.459; A., 1934, 1405444 :BIOCHEMISTRY.ethyl alcohol and organic acids produced in the earlier stages becomethe sources of carbon and the medium becomes increasingly alkaline.The stages at which changes of carbon and nitrogen sources takeplace are identical. The exhaustion of sugar also coincides with adefinite change in the ash content of the mycelium.The production of urea from peptone by various species ofAspergiZZus and Penicillizim is also influenced by the source ofcarbon available.T. Chrzaszcz and M. Zakomorny16 show that,in general, small concentrations of glucose favour the accumulationof urea, but larger amounts have the reverse effect and favour theproduction of citric and oxalic acids. Ethyl alcohol and aceticacid invariably lower the yield of urea. It is probable that guan-idine is an intermediate product in this degradation process. Thetwo changes guanidine I_, urea, and urea --+ ammonia areentirely separate functions and the effects of the various carbon-aceous materials represent the resultant of their separate actions onthe individual stages.The observations of T. Miwa and S. Yoshii l6have a bearing on this point. A . niger and P. glaucurn are found toproduce urease as well as urea on ammonium nitrate media, or fromprotein hydrolysates, the formation of the enzyme being favouredby the presence of glucose, I n media containing large amountsof ammonium nitrate, M. Lemoigne and R. Desveaux record theproduction of hydroxylamine by A. niger.Production of Organic Acids by Moulds.-The mechanism of theformation of citric acid by moulds is still a matter of controversy.V. S. Butkevitsch and colleagues reject the view that sugars areconverted into citric acid through the intermediate formationof acetic acid.19 Citric acid formed in sodium acetate media issaid to be derived from mycelium and not directly from the acetate,and the increased production of acid resulting from larger additionsof acetate t o the medium is ascribed to the strong inhibitory actionof acetate on the utilisation of citric acid by the mould.The form-ation of citric acid and the utilisation of acetates by fungi are twodistinct processes. The source of oxalic acid may be mycelium, thesugar, or the sodium acetate. I n another publication 2o it is contendedthat oxalic acid is formed in the mycelium by fission of sugarswithout the intermediate production of formic acid. This is15 Biochern. Z . , 1934, 213, 31 ; 275, 97 ; A., 1934, 1263; 1935, 254.16 Sci. Rep. Tokyo Bunrika Daigaku, 1934, 1, 243 ; A., 1934, 928.l7 Compt.rend., 1935, 201, 239; A., 1166.18 With E. V. Menzschinskaja and E. I. Trofimova, Biochem. Z., 1934, 372,Is Ann. Reports, 1932, 29, 272.?O V. S. Butkevitsch, Biochem. Z., 1934, 272, 371; A., 1934, 1263.290, 364; A., 1934, 1139, 1263POLLARD. 446contrary to the views of T. Chrzaszcz and M. Zakomorny,21 whopostulate the decomposition of formic acid into oxalic acid andcarbon dioxide. This theory is supported by observations ofK. Bernhauer and E’. Slanina 22 that A . niger gives 60% yields ofoxalic acid from sodium formate in dilute solutions. At higherconcentrations of the formate there is considerable degradationto carbon dioxide and water and the yield of oxalic acid is muchlowered. High yields (60-77%) of oxalic acid are also obtainedfrom acetic, succinic, fumaric, glycollic, aconitic, and citric acids.In a later paper Butkevitschz3 explores another aspect of thisproblem by examining acid production by A .niger in relation tomineral nutrition. The accumulation of citric acid is associatedwith a deficiency of phosphorus and sulphur or of nitrogen. Yieldsof gluconic and oxalic acids are also lowered by inadequate suppliesof phosphorus or nitrogen or magnesium, but are increased by lackof sulphur. Deficiency of potassium intensifies the production ofoxalic and, to a less extent, of gluconic acids, whereas simultaneousshortage of potassium and magnesium causes the almost completedisappearance of citric acid. M. Giordani24 records that theaccumulation of citric acid by A .niger is lowered by the presenceof iron salts, which tend to accelerate its oxidation to oxalic acidand carbon dioxide. This effect and also the inhibiting action ofnitrogen compounds on citric acid production are said to becorrected by addition to the medium of a sodium citrate buffer.25The retarding influence of iron salts on the production of gluconicacid by several species of PeniciZZium is recorded by A. Angelettiand colleagues,26 who show that, if the amount of iron present issmall, the ultimate yield of gluconic acid, though delayed, maybecome even higher than that in iron-free media.According to R. Bonnet and R. Jacquot 27 the amount of oxalicacid produced by A . niger increases with the age of the culturewhen nitrogen is supplied as potassium nitrate, but none is formedwhen ammonium salts are used.In nitrate-cultures the acid occursas an unutilisable by-product in amounts regulated by the energybalance of the culture. Citric acid is formed in spores, is trans-located to mycelium during growth, and subsequently reappears inthe substrate during the autolysis of old cultures.21 Biochem. Z., 1935, 279, 64; A., 1166.22 Ibid., 1934, 274, 97; A., 1935, 124.2s With A. G. Timofeeva, ibid., 1935, 275, 405; A., 406.24 Chimica e l’lnd., 1935, 17, 77 ; A., 662.25 V. Bolcato, Qiorn. Chim. ind. appl., 1934,16, 552; A., 1935, 255.26 With L. Merlo, Ann. Chirn. appl,, 1934, 24, 468; A., 1934, 1405; with27 Cornpt. rend., 1935, 200, 1968; A,, 1027.D. Ponte, ibid., 1935, 25, 217; A., 1166446 RIOOHEMTSTRY.The respiratory exchange of A.niger is investigated by S.Michael.28 In glucose media with excess of calcium carbonate, theCO, : 0, ratio is maintained approximately at unity. In the earlystages of growth a very small proportion of the sugar is used forpurely respiratory purposes, the majority being oxidised to gluconicacid. Under these conditions the carbon dioxide output is derivedmainly from the carbonate. In older cultures in which citric andoxalic acids are being formed, the respired carbon dioxide forms anincreasing proportion of the total. In non-neutralised media theperiod of active formation of acid is marked by a considerabledecrease in the respiratory quotient, which, however, againapproaches unity at a laher stage.Gluconic acid production isshown by E. Kardo-Syssojeva 39 to be favoured by excess of calciumcarbonate. Addition to the nitrogen supply results in still largeraccumulations of the acid in acid media, but has an inhibitoryaction in the presence of calcium carbonate.Fatty Products of Fungal Demelopment .-Examination of the fatproduction of Penicil2iu.m javani~um,~O amounting a t times to40% of the dry matter of the mycelium, shows this t o reach itsmaximum a t a period of about one-third of the full growth period(dry weight increase) of the culture. High-sugar media (30-40%)are necessary for optimum fat yields, whereas for optimum mycelialgrowth approximately 20% of sugar is required. The maximum fatyield is coincident, in point of time, with maximum titratableacidity in the substrate.G. E. Ward and G. S. Jamieson 31 obtain,by hydrolysis of the fat, palmitic, stearic, oleic, a- and p-linoleic, andn-tetracosoic acids. F. M. Strong and W. H. Peterson32 find thesame acids, though in different proportions, in Aspergillus sydozui,together with a phospholipin. The unsaponifiable fraction of thealcohol-ether extract consists of 66% of sterols, among whichergosterol is identified. The lipins of Penicillium aurantiobrunneumyield a similar series of compounde.33The production of lipins by moulds varies considerably with theconditions of culture. For instance, various species of Aspergillusgrown on glucose-malt media produce a higher proportion of28 Biochem. Z., 1934, 274, 397; A., 1935, 254.28 Ibid., 1933, 266, 337; A., 1934, 112.3O L.B. Lockwood, G. E. Ward, 0. E. May, M. T. Herrick, and H. T.O’Neill, Zerttr. Bakt. Par., 1934,II, 90,411 ; A., 1935, 535; also G. E. Ward,L. B. Lockwood, 0. E. May, and H. T. Herrick, I n d . Eng. Chem., 1935, 27,318; A., 662.31 J . Amer. Chem. SOC., 1934, 56, 973; A., 1934, 697.32 Ibid., p. 952; A., 1934, 697.33 E. H. Kroeker, F. M. Strong, and W. H. Peterson, ibid., 1935, 57, 364;A., 535POLLABD. 447lipins and less protein matter than when grown on glucose-mineralsalt preparation^.^^ In an examination of the production of lipinsby A . Jischeri, E. A. Prill, P. R. Wenck, and W. H. Peterson 35 showthat different strains show variations in fat content, in the iodinevahxe of the fats, and in the proportions of phospholipins and sterolsproduced.With individual strains, the following general effectsare noted. With glucose-ammonium nitrate-mineral salt mediaan increase in glucose concentration is associated with a higher fatproduction, a decrease in sterols, and a lowering of the iodine valueof the fatty acids. Similar effects on the two last-named factorsalso result from increases in the nitrogen supply. In the rangepH 2-0-8-0 the fat yield increases with alkalinity. Higher temper-atures decrease fat production. Exhaustion of glucose from themedium is followed by a decrease in the percentage of fat andphospholipin, although the iodine value of the fat suffers no furtherchange.New Substances isolated from Mould Cultures.-The outstandingwork of Raistrick and co-workers requires far greater space foradequate review than is available here, but some brief referencemust be made to certain of the new substances which have beenisolated, characterised, and in a number of cases synthesised in hislaboratory, following intensive examination of mould products.Among the metabolic products of Penicillium Charlesii were isolatedcarolic, C,HloO,, carohzic, C9H1,0,, carlic, CloHlo06, and carlosic,C1oH1206, acids.Structurally, these acids are found to be relatedto ascorbic acid and show similarities in absorption spectra.36Penicillium minio-luteurn grown on a glucose medium yields minio-luteic acid, identified as the y-lactone of ap-dihydroxy-py-dicarboxy-n-tetradecoic acid.37 Three pigments are isolated from the Asper-gillus glaucus series, vix., flavoglaucin, C19H2803, auroglaucin,C19H2,03, and rubroglaucin, C16H1205 .38 These pigments areapparently specific to the series and serve also to subdivide theseries into three groups according to their distribution.A yellowpigment, fulvic acid,39 C14H1208, occurs in Yenicillium griseofulvum,P. $exuosum, and Y. brefeldianum when grown on a glucose-1934, 11, 89, 370; A., 1934, 810.34 L. M. Pruess, E. C. Eichinger, and JV. H. Peterson, Zentr. Bakt. Par.,35 Biochem. J., 1935, 29, 21; A., 255.36 P. W. Clutterbuck, W. N. Haworth, H. Raistrick, G. Smith, and M.Stacey, Biochem. J., 1934, 28, 94; A., 1934, 452; P. W. Clutterbuck, H.Raistrick, and F. Reuter, ibid., 1935, 29, 300, 871, 1300; A., 327, 662, 898.3 7 J.H. Birkinshaw and H. Raistrick, ibid., 1934, 28, 828; A., 1934, 927.38 B. S. Gould and H. Raistrick, ibid., p. 1640; A., 1934, 1263.39 A. E. Oxford, H. Raistrick, and P. Simonart, ibid., 1936, 29, 1102; A.,786448 BIOCHEMISTRY.ammonium tartrate-mineral salt substrate. Certain strains ofAspergillus terreus produce terrein, C,H,,O,, from glucose underconditions in which other strains yield only succinic and oxalicacids .40E. Nishikawa records the isolation of mellein, Cl,Hl,O, [identifiedas the lactone of 6-cc (or p)-hydroxypropylsalicylic acid], fromAspergillus rneZZeus.41 Oosporin, ClOH4O2, and aurantin areisolated from Oospora ~ u r a n t i n . ~ ~Algce.The output of research work relating to the biochemistry of algaemaintains a steady level, although, perhaps of necessity, it is ofa somewhat scattered character.Nevertheless it is of interestto separate a brief record of recent work in this field from the ratheroverwhelming volume of publications in general plant biochemistry.General relationships between light intensity and the distribution,colour, and carbon assimilation of algae form the subject of extensiveinvestigations by C. M ~ n t f o r t , ~ ~ in the case of green, brown, andred alga3, and by A. Seybold44 in the case of submerged marinespecies. R. Lami45 examines the distribution of marine typesfrom sea-shore pools in relation t o the reaction of the aqueoussubstrate and to lighting. The reaction of the water immediatelysurrounding the algz is characteristic of the species, provided thereis adequate exposure to light, but, with insufficient illumination,becomes dependent on the actual light intensity. F. E. Meier,46working with unicellular green algae, shows that in many casessome chlorophyll is produced even in darkness, and that bestgrowth is obtained with intermittent illumination. Within certainlimits, an increase in light intensity causes a proportionate increasein the number of cells produced. Xtichiococcus bacillaris producesgood growth in red and infra-red lights. Chlorophyll formation inChloreZZa vuZgaris and other species is examined by G. P~lacci.~'In iron-free media, chlorophyll continues to be produced andgrowth is maintained if magnesium pyrrole-2-carboxylate is supplied.If magnesium is supplied in the alternative form of sulphate,40 H. Raistrick and G. Smith, Biochem. J., 1935,29, 606; A., 662.41 J . Agric. Chem. SOC. Japan, 1933, 9, 772, 1059; A., 1934, 562, 810.42 H. Nishikawa, Proc. Imp. Acad. Tokyo, 1934, 10, 414; A., 1934, 1139.43 Jahrb. wiss. Bot., 1934, '79, 493; A . , 1934, 1273.44 Ibid., p. 593; A., 1934, 1274.45 Compt. rend., 1934, 199, 615; A., 1934, 1274.48 Smithsonian Miscell. Coll., 1934, 92, No. 5, 14 pp.; No. 6, 27 pp.; A.,4 7 Ber. deut. bot. Ges., 1935, 53, 540; A., 1039.1934, 1418POLLARl). 449new growth obtained has a high leucoplast but no chloroplastcontents. The latter reappears when the pyrrole compound isagain added. The theory is thus confirmed that the function ofiron in relation to chlorophyll production is that of a catalyst inthe formation of the pyrrole derivative. Temperature variationsaffect the respiration rate and carbon assimilation of algae in differentways.48 In Stichococcus bacillaris, parallel effects on the two functionsare induced. In Oocystis, the same occurs at temperatures up to 22",above which respiration increases the more rapidly. On the otherhand, temperature affects the respiration of Chlamydornonas morestrongly than the assimilation rate only at the lower ranges oftemperature.Several papers deal with the distribution of cellulose and associatedcompounds. In a number of red and brown algae G. L. Naylor andB. Russell-Wells 49 record 2--15% of cellulose. The separation ofcellulose from Laminariu digitutu by T. Dillon and T. Otuama50yielded samples giving only glucose on complete hydrolysis. Inseaweeds examined by P. Klason 51 there occurred 60% of cellulose,30% of lignin, and smaller proportions of methyl pentoses. Thelignin is characterised by having no methoxy-groups and by possess-ing a hydroxyl instead of an aldehydo-group. The formulaNH,*C,H,( OH)*CH,*CH( OH)*CH,*OH is suggested. The pro-portion of xylose : hexose is 1 : 1, as compared with 3 : 2 in thehigher plants. Following up earlier work, H. Colin and E. Gu6guen52have established the presence of floridoside in many varieties ofPloridece.In an investigation of the metabolism of calcareous a l p , P. Haasand T. G. Hill 53 demonstrate the presence, in aqueous extracts ofCorallinu oficinalis, of hexa-acetylfloridoside and a polypeptide ofaspartic acid. Relationships between seasonal variations of thefloridoside and amino-nitrogen contents indicate that the formationof peptides is attributable to a lack of balance between the carbonand the nitrogen metabolism. Seasonal variations are also tracedin the ratio of CaCO,:MgCO, in the incrustations of C.squamata.54The presence of sterols in certain alge is noted by E. Montignie.5548 F. van der Paauw, Planta, 1934, 22, 306; A., 1935, 549.4~4 Ann. Bot., 1934, 48, 635; A., 1934, 1146.60 Sci. Proc. Roy. Dublin Soc., 1935, 21, 147; A., 550.6 1 Svensk Kern. Tidskr., 1935, 47, 215; A . , 1434.62 Compt. rend., 1933, 197, 1688; A , , 1934, 121.68 Biochem. J., 1933, 27, 1801; A., 1934, 121.54 P. Haas, T. G. Hill, and W. K. H. Kizrstens, Ann. Bot., 1935, 49, 609;65 Bull. SOC. chim., 1935, [v], 2, 194; A., 673.A., 1178.REP.-VOL. XXXII. 450 BIOCHEMISTRY.Heilbron and colleagues,56 in a detailed examination of Fucusvesicuhsus, have isolated and characterised a new sterol, fucosterol,C,,H,80, which also occurs in FeZvetia camliculata and, togetherwith sitosterol, in Nitellu opaca. It is regarded as the characteristicalgal sterol. In a further paper,57 P. vesicuhsus is shown to containfucoxanthin (probably a dihydroxycapsorubin) but no xanthophyll,and from the dead tissue, @-carotene and zeaxanthin are isolated.Lutein, taraxanthin, and hentriacontane occur in several speciesexamined. From Nitella opam and Oedogonium is obtained aphytosterolin, C&Hs606. The algal lipins appear to be characteristicfor each species and related to their habitat.A. G. P.A. G. POLLARD.C. P. STEWAF~T.J. STEWART.66 I. M. Heilbron, R. F. Phipers, and H. R. Wright, J . , 1934, 1572; A.,67 I. M. Heilbron, E. G. Parry, and R. F. Phipers, Biochem. J., 1935, 29,1934, 1347.1369, 1376, 1382; A., 1040

ISSN:0365-6217    

DOI:10.1039/AR9353200400

出版商:RSC    

年代:1935

数据来源: RSC

摘要:

ANALYTICAL CHEMISTRY.DURING the period covered by this Report more than 1500 abstractsof papers concerned with analysis have appeared in British ChemicalAbstracts, and it will at once be evident that no attempt to cover thewhole field could be made. Physical methods of analysis, which haveformed the subject of special monographs in the last two Reports,have been omitted, and other subjects such as colorimetry andmineral analysis must be left to a later Report. It has been con-sidered advisable in this year’s survey, however, to devote a specialsection to water analysis, which was last dealt with as a separatesubject in the Annual Report for 1926.INORGANIC ANALYSIS.Quantitative.Storage of Weights.-A subject of interest and concern to allengaged in accurate quantitative work, especially in view of theincreasing use of methods dealing with amounts of material on themicro- and the semi-micro-scale, is the change in mass which weightsmay undergo during their storage and use. In a timely research,J.J. Manley has investigated the nature, origin, and masses ofthe films which frequently appear on weights. The most pronouncedfilms are acquired by gilded weights, and chromium-plated onessuffer the least change. The exceptional density of these filmsand their corroding powers have been traced to the acid characterof the glue which is used in lining the boxes, and, occasionally,to the imperfect washing of the dyed velvet itself. In view of thesefindings, a simple method of storing has been worked out, in whichthese difficulties are overcome by using charcoal to absorb andretain any gases which may be developed, and by which the con-stancy in mass of precision weights is ensured.2Conrady System of Weighirq.-In 1922, A.E. Conrady describeda method of weighing which gives an accuracy of 0.001 mg. with aload of 100 g., using an analytical balance of robust design withonly slight structural modifications. The underlying principle aimsat eliminating, by a process of cancellation, the errors involved in anPhil. Mag., 1933, [vii], 16, 489; A., 1933, 927.Proc. Roy. SOC., 1922, [A], 101, 211; see Ann. Reports, 1930, 27, 208.2 Idem, ibid., 1935, [vii], 19, 243; A., 467452 ANALYTICAL CHEMISTRY.ordinary double weighing. -W-. 11. J. Vernon * again directs atten-tion to this method by describing in detail its application to routinework. The method appears to deserve more general considerationthan it has received, and should be of service in determinations ofa semi-micro nature, or even in work on a micro-scale where theexpense and disadvantages of a micro-balance have to be avoided.Standards for Volumetric Analysis.-During the period underreview, attention has been devoted to volumetric standards (seealso Ann.Reports, 1934, 31, 295). Cyanogen bromide, which canreadily be obtained and preserved in a condition of analytical purity,has been applied t o the standardisation of acids, sodium tbiosul-phate, and silver nitrate. Adipiq6 ~alicylic,~ and t,h-cumene-sulphonic8 acids have each in turn been recommended as acidi-metric standards.R. H. Curtis 9 standardises hydrochloric acidagainst Iceland spar, precipitates the calcium chloride formed asoxalate, and uses this to standardise potassium permanganate,thus obtaining a direct link to oxidation-reduction determinations.J. W. Young l o also describes a method for hydrochloric acid usingcalcite.In this connexion it is indeed surprising that the constant boiling-point method for the preparation of a standard solution of thisacid l1 is not more widely used. This excellent method is quick,exact, and compares well with other accepted methods,12 and itgives good results even in inexperienced hands.Sodium carbonate suitable for standardisation purposes is pre-pared 13 by heating sodium hydrogen carbonate a t 156-280",or at the boiling point of nitrobenzene for 100 minutes. J.Lindnerand N. Figala l4 prefer to heat it to constant weight at 300°, andstate that the hydrochloric acid required for a given amount ofsodium carbonate is, cin the average, 0.006~0 less than theChem. and Ind., 1934,53,211; A., 1934, 384.M. Merller, 2. anal. Chem., 1934, 99, 351; A., 1935, 183.A. H. Meyling, J . S. African Chem. Inst., 1935, 18, 23; A., 462; F. T.van Voorst, Chem. Weekblad, 1928, 25, 22; A., 1928, 262; N. Schoorl, ibid.,p. 73 ; A., 1928, 262.S . gkramovskf, Coll. Czech. Chem. Gomm., 1933, 5, 143; A., 1933, 686.D. Tischtschenko, J . Appl. Chem. Russia, 1933, 6, 1182; A., 1934, 267.Chem. and Id., 1934,53,135; A., 1934, 380.lo Canadian Chem.Met., 1934, 18, 218; A., 1935, 315.l1 G. A. Hulett and W. D. Bonner, J . Amer. Chem. SOC., 1909, 31, 390; A.,1909, ii, 342; W. F. Hillebrand and G. E. F. Lundell, " Applied InorganicAnalysis," 1929, pp. 135, 142.l2 G. W. Morey, J . Amer. Chem. SOC., 1912, 34, 1027; A., 1912, ii, 986.l3 J. Stalony-Dobrzanski, Rocz. Chem., 1934, 14, 1106; A., 1935, 315; seel4 2. anal. Chem., 1933, 91, 105; A., 1933, 135.also Hillebrand and Lundell, op. cit., p. 137THEOBALD : INORGANIC ANALYSIS. 453theoretical. A new variation of normal procedure is introduced byL. Waldbauer, D. C. McCann, and I;. F. Tuleen,15 who wash theanhydrous carbonate with alcohol and dry it a t 110". They findthat it does not decompose below 450", a temperature well abovethat required for the preparation from the acid carbonate, butE.Preston and W. E. S. Turner l6 obtain a slight decomposition,apparently due to atmospheric moisture, on heating for a day inair a t 400". They recommend that the pure carbonate for analyticalpurposes be heated not above this temperature.The error introduced in acidimetry by the presence of carbonatein standard alkali, discussed at length by T. Milobedzki and W.Szczypiriski,17 varies according to the conditions of addition ofthe alkali to the acid, and to the indicator used. They recommendthe use of carbonate-free solutions prepared by Sqrensen's method.A. V. Filosofov l8 determines the titre of potassium permanganatesolutions by means of calcium carbonate, and potassium ferrocyanidein the presence of sulphuric acid can conveniently be used forO.OlN-solutions with erioglaucin as indi~at0r.l~ According toW.Wesly,20 iron prepared from the pentacarbonyl is purer thanpiano wire and is as good as electrolytic iron for this standardisation.I n the past, much confidence has been placed in the standardis-ation of potassium permanganate by means of sodium oxalate,which is regarded in many quarters its one of the best fundamentalvolumetric processes available. Now, however, the usual methodof titration 21 has been called in question. In a critical examinationof the subject, R. M. Fowler and H. A. Bright 22 find that the slowaddition of the permanganate to a hot solution of the oxalate indilute sulphuric acid (2 : 98) leads to results which may be as muchas 0.4% high when compared with other primary standards, and thatin order to obtain satisfactory agreement with the values found withiron, arsenious oxide, or potassium dichromate, a modified pro-cedure, which they detail, is necessary. I n view of the importanceof this standardisation, it is to be hoped that independent con-firmation of this work will soon be made.Potassium dichromato is standardised by treating arsenious acidl6 Ind.Eng. Chem. (Anal.), 1934, 6, 336; A., 1934, 1188.l6 J . SOC. Glass Tech., 1934,18, 1 8 2 ~ ; A., 1935, 48.17 Rocz. Chem., 1934, 14, 1088; A,, 1935, 315; see also W. W. Kay andH. L. Sheehan, Biochem. J., 1934,28, 1795; A., 1934, 1322.l8 J . Appl. Chem. Russia, 1934, 7, 1085; A., 1935, 318.19 E.J. de Beer and A. M. Hjort, Ind. Eng. Chem. (Anal.), 1936, 7, 120; A.,20 2. anal. Chem., 1933,91,341; A., 1933,246.21 R. S. McBride, J . Amer. Chem. Soc., 1912, 34, 393; A., 1912, ii, 494.23 J . Res. Nat. Bur. Stand., 1935, 15, 493.597454 ANALYTICAL CHEMISTRY.with less than its equivalent of dichromate and finishing the titrationwith ceric sulphate or potassium permanganate, osmium tetroxidebeing used as catalyst and o-phenanthroline ferrous complex asindicator .23The factors which affect the standardisation of sodium thiosul-phate with potassium dichromate have been studied in detail byH. C. S. Snethlage.24 Reproducible results can be obtained onlyin dilute solutions, and the accuracy of the determination is affectedby illumination, concentration of acid, and rate of addition of potass-ium iodide.With sulphuric acid these factors are less importantthan when hydrochloric acid is used. Results accurate to 0.01%are claimed for the procedure finally recommended.Limiting ratios of the weights of the reagents concerned in thisstandardisation are laid down by Z. N a l ~ a i , ~ ~ and acidimetricand alkalimetric titrations of sodium thiosulphate are alsodescribed.26The stability of aqueous solutions of this reagent and methods fortheir preservation still continue to be investigated. R. A. Kolliker 27sterilises glassware and solutions by live steam and, by maintainingthem under aseptic conditions, obtains a change in normality ofonly 0.1% during a period of 500 days, whilst 3’.J. Watson 28preserves the titre almost, indefinitely by buffering to pH 9-0-96;with 0-O1M-borax ; 0-1N-solutions remained unchanged after3 years. Solutions of this concentration are unaffected in titre bybubbling pure carbon dioxide or oxygen through them for 2-3hours, according to I. Bellucci and I. Damiani,2Q who attribute aslow decrease in normality to decomposition by water, followed byoxidation by atmospheric oxygen. In dealing with the stabilityof certain volumetric solutions, E. P. Hedley 30 finds that 0.1N-sodium thiosulphate showed the same factor for approximately3 months, but he prefers arsenious oxide solution, preparedaccording to Kolthoff’s dire~tions,~~ as a primary standard.The purification of K2TiO(C20,),,2H20 for the preparation ofz3 H.H. Willard and (Miss) P. Young, Ind. Eng. Chem. (Anal.), 1935, 7,24 Rec. trav. chim., 1934, 53, 567; A., 1934, 745.25 Bull. Fishery Exp. Sta. Cov. Cen. Chosen, 1933, D, No. 3, 1 ; A., 1934,26 A. Sconzo, Id. chirn., 1933, 8, 297; A,, 1933, 477.2 7 2. anal. Chem., 1932, 90, 272; A., 1933, 41.28 J . SOC. Chem. Id. Victoria, 1932,32,679; A., 1933, 136.20 Gazzetta, 1934, 64, 69; A., 1934, 619.30 Proc. VI Congr. S. Afr. Sugar Tech. ASSOC., 1932, 6; A., 1932,31 “ Volumetric Analysis,” 11, 363.57; A., 317.619.1101THEOBALD : INORGANIC ANALYSIS. 455iron-free solutions of titanium sulphates,32 and that of pure titaniumdioxide from the tetrachloride and its use in standardising ferricammonium sulphate 33 are also described.There appears to be a need for a review of the whole subjectof primary and secondary standards for volumetric analysis.Acritical consideration of published methods by a group of experiencedanalysts should do much to clarify the whole position, and a selectionby them of trustworthy methods and procedures would be invaluableto all engaged in accurate analytical work.Indicators.-Indicators which have been recently investigatedmust receive brief mention. They include diphenylcarbazone,Fe,[Fe(CN),], containing an excess of Fe(CN)6”’,34 diamine-fast-bordeaux-6BS and diamine- f as t -violet -BBN,35 o-cresolphthalein 36and dichlorofluorescein 37 as adsorption indicators for argento-metric titrations, Victoria-blue-BX as an internal indicator in~eriometry,~~ and a-naphthaflavone for the titration of arsenicand antimony solutions with potassium b r ~ r n a t e .~ ~ For the arsenictitration, Ponceau-SR, methylene-blue, Bordeaux-By safranine,Azure-11, chrysoidine, and saffron-yellow are all said to be moresuit able than methyl- orange .40Among many organic compounds examined, phenyl-p- and-m-toluidine are satisfactory oxidation-reduction indicators foruse with dichromate in the absence of mercury salts, and naphthidineand a product derived from the action of ethyl sulphate on acetyl-diphenylamine can be used even in their presence.41 The sodiumsalt of diphenylbenzidinesulphonic acid is also recommended as anindicator of this type.4232 R. Roseman and W.M. Thornton, jun., J . Amer. Chem. SOC., 1935, 57,33 W. W. Plechner and J. M. Jarmus, I d . Eng. Chem. (Anal.), 1934,6,447;34 E. Chirnoagii, 2. anal. Chern., 1935,101,31; A., 719.36 E. A. Kocsis, 2. anorg. Chem., 1935, 221, 318; A., 316.36 Y. Uzumasa and Y . Mikaye, J . Chem. SOC. Japan, 1934, 55, 627; A.,1935, 53.37 H. R. Fleck, R. F. G. Holness, and A. M. Ward, Analyst, 1935, 60, 32;A., 315; K. Bambach and T. H. Rider, I d . Eng. Chern. (Anal.), 1935, 7, 165;A., 835.38 J. M. Caldwell and M. E. Weeks, Trans. Kansas Acad. Sci., 1934,37,117;A., 1935, 1339.39 E. Schulek, 2. anal. Chem., 1935, 102, 111; A., 1215; R. Uzel, Coll.Czech. Chem. Comrn., 1935, 7, 380; A , , 1471.40 T. Sotgia-Rovelli, Boll. chirn.-farm., 1935,74,265; A., 718.4 1 L.E. Straka and R. E. Oesper, I d . Eng. Chem. (Anal.), 1934, 6, 465;*z L. A. Sarver and W. von Fischer, ibid., 1935, 7, 271 ; A., 1092.328 ; A., 460.A., 1935, 56.A., 1935, 56456 ANA.LYTICAL CHEMISTRY.p-Methylumbelliferone provides a fluorescing indicator for thetitration of coloured sol~tions,4~ and the magnesium compoundof 8-hydroxyquinoline one for titrating acids with alkaLli~1.43~Benzoylauramine-G is described as a new indicator for Kjeldahlnitrogen determinations .44The indicator properties of many dinitroanilineazonaphthol-sulphonic acids are described by H. Wenker,45 but none is as goodan indicator as nitrazine-yellow46 which, together with its 8-halogen derivatives, has been further investigated?'Mixed indicators giving sharper end-points than their con-stituents alone are recommended by s.Hahnel and B. IlolmbergY4*and by H. A. J. P i e t e r ~ , ~ ~ who regards methyl-orange as the bestindicator for carbonate tit rat ions.A study of the salt error of methyl-red, phenolphthalein, andbromothymol-blue in certain acid-base titrations 50 has been made,and a useful introduction t o some of the applications of the moremodern indicators has also been published 51 during the periodunder review.Reagents .-In addition to the now well-known reagents, 8-hydroxyquinoline, dithizone, etc., the use of which is being steadilydeveloped and extended, three others appear to be worthy of notice.Thiolucet- f3-naphthazide. This reagent, for convenience named" thionalide," forms complex derivatives with many metals,and its application in analysis has been surveyed by R.Berg andW. R ~ e b l i n g . ~ ~ The metals can be determined directly by weighingthe complex, by ignition, by titration with iodine, or colorimetricallyand nephelometrically. The sensitivity of the reagent permitsits use in micro- as well as in macro-determinations; for silver,this is such that silver ions can be detected in filtrates from pre-cipitated silver chloride. In sodium hydroxide-cyanide solution,with or without tartrate, it is specific for thallium and is especiallysuitable for toxicological work.43 A. G. Pukirev and M. S. Maslova, Zavod. Lab., 1934, 3, 1038; A., 1935,316.435 H. R. Fleck, R. F. G. Holness, and A. M. Ward, Zoc. cit., ref.(37).44 J. T. Scanlanand J. D. Reid, I d . Eng. Chem. (Anal.), 1935, 7, 125; A.,4 5 Ibid., p. 40; A., 315.46 Idem, I d . Eng. Chem., 1934,26, 350; A., 1934, 500.4 7 E. S. Vasserman, Zavod. Lab., 1934, 3, 868; A., 1935, 52.48 Xvensk Kem. Tidskr., 1935, 47, 4; A., 462.49 Chem. Weekblad, 1935, 32, 539; A,, 1336.50 S. Kilpi and A. Laaksonen, Soumen Kern., 1935,8, B, 9; A., 594.5 1 A. D. Mitchell, Institute of Chemistry, 1934; A., 1935, 182.62 Ber., 1935,68, [B], 403; A., 591; Angew. Chem., 1935,48,430, 597; A,,639.950, 1338; R. Berg, ibid., 1934, 47, 404THEOBALD : INORGANIU ANALYSIS. 457Thiolbenzthiuzole. This is used for copper in presence of cad-mium, the metals of Group IIIb, alkaline earths, and alkalis,but other metals of Group 11, as well as silver and thallium, arequantitatively pre~ipitated.~~ It also serves for macro- and micro-determinations of cadmium when other metals, except copper, areabsent.5*Phosphomolybdic acid.J. W. Illingworth and J. A. Santos 55revive interest in the possibilities of this acid as an analyticalreagent. As a precipitant for caesium or potassium, it is more sen-sitive than either chloroplatinic acid or sodium cobaltinitrite,and its application to the determination of potassium is being in-vestigated.Grauimetric and Volumetric Methods for the Determination of theElements.-The papers published on this subject during the periodunder review are as numerous as ever and the task of making asuitable selection has not been easy. Many doubtless excellentmethods will receive no mention.The choice has been based partlyon the personal appeal of a method, but mainly, it is hoped, on itspossible utility. Before they replace well- tried and satisfactoryprocedures, new methods must establish a claim to one or moredefinite advantages, such as greater ease of manipulation and speedof execution, a more favourable conversion factor, and, most im-portant of all, a cleaner separation from accompanying ions. It isnot sufficient that they should be merely new. Methods which areapplicable only to pure solutions of a metal would appear to be oflittle value, for, in practice, it is the separation from other ionswhich is of chief importance and constitutes the main difficulty ineffecting an accurate analysis.Furthermore, although all newmethods of determination and detection are welcome and have theirpossible uses, it is unfortunate that so many of them apply to elementsfor which satisfactory methods already exist, whilst for elementssuch as tin, calcium, or potassium, for example, for which separationsare scarce or leave much to be desired, little seems to be forthcoming.Small amounts of silver in the presence of lead, zinc,gold, bismuth, etc., can be determined titrimetrically or colori-metrically with dithiz0ne,5~ which has also been applied in thedetermination of traces (0.0005-0.02 yo) of thallium in the presenceof other metals.57Group I .b3 G. Spacu and M. Kurag, 2. anal. Chem., 1935,102,24; A., 1094.64 Idem, ibid., p.108; A., 1216.6 5 Nature, 1934, 134, 971; A., 1935, 185.56 H. Fischer, G. Leopoldi, and H. von Uslar, 2. anal. Chem., 1935, 101,5 7 L. A. Haddock, Amly8t, 1935,60, 394; A., 960.1 ; A., 719.P 458 ANALYTICAL CHEMISTRY.#roup I I . Elimination of interference by bismuth has beeneffected in the dithizone method for lead,58 which is sensitive toapprox. 0-001 mg. of lead in metals 59 and in biological material.60H. H. Willard and J. J. Thompson 6 1 separate this metal from copper,cadmium, nickel, zinc, etc., by precipitation as Pb,H,(IO,),, whichcan be either weighed or determined volumetrically. Lead canalso be precipitated as Pb(C,H,O,N), by anthranilic acid 62 andsimilarly determined. The conditions for precipitation of thechromate in forensic analysis have been studied,63 but the methodcannot be used in presence of large amounts of other metalsq6*Volumetric methods 65 and a nephelometric micro-method 66for mercury are described,An investigation of the behaviour of material containing copperon fusion with sodium carbonate and sulphur shows that the copperdissolved in an aqueous extract of the melt increases with the pro-portion of sulphur used a'nd is augmented by the presence of tin;a quantitative separation of the copper from such material is notpossible.67 This is in harmony with the observation that the knownsolubility of cupric sulphide in alkaline polysulphides increasesrapidly with the sulphur content of the latter, its concentration,and temperature.In sodium monosulphide, the cupric sulphideis practically insoluble.6* Further work has been carried out 69on the separation of copper by means of salicylaldoxime and dimer-~aptothiodiazole,~0 whilst p-homosalicylaldoxime is recommended 71for the detection and determination of both copper and nickel.Quinaldinic acid also is used for the micro-determination of the former5 8 C.E. Willoughby, E. S. Wilkins, jm., and E. 0. Kraemer, I d . Eng.Chern. (Anal.), 1935, 7, 285; A., 1094.58 E. S. Wilkins, jun., C. E. Willoughby, E. 0. Kraemer, and F. L. Smith,ibid., p. 33; A., 531.6o Idem, ibid. ; 0. B. Winter, H. M. Robinson, F. W. Lamb, and E. J. Miller,ibid., p. 265; A., 1094.61 Ibid., 1934, 6, 425; A., 1935, 55.62 H. Funk and F. Romer, ibid., 1935, 101, 85; A., 720.63 K. Holl, ibid., 1935, 102, 4; A., 1182.64 A.W. Middleton, J . Ind. Hygiene, 1935, 17, 7 ; A., 317.6 5 S. Skramovsky and R. Uzel, casopis cxechoslov. Ldk., 1934, 14, 33; A.,1934, 1323; G. Denigbs, Bull. SOC. Pharm. Bordeaux, 1934, 72, 5 ; A., 1935,186; M. Schtschigol, J . Appl. Chem. Russia, 1935, 8, 160; A., 950.O 6 S. I. Ssinjakova, 2. anal. Chem., 1935,100, 190; A., 464.6 7 R. Holtje and W. Kahmen, 2. anorg. Chem., 1935, 223, 234; A., 1088.6 8 R. Holtje and J. Beckert, ibid., 1935, 222, 240; A., 576.6g M. Ishibashi and H. Kishi, J . Chem. Soc. Japan, 1934, 55, 1060, 1065,70 P. Ray and J. Gupta, J . Indian Chem. SOC., 1935, 12, 308; A., 1094; J.71 C. H. Kao and K. H. Chen, J . Chinese Chem. SOC., 1935, 3, 22; A., 720.1067 ; A., 1935, 720.Gupta, ibid., 1934, 11, 403; A., 1934, 982THEOBALD : INORGANIC ANALYSIS.459by a method which separates it from lead, manganese, nickel,phosphate, etc., if suitable precautions are taken in washing. 72In the usual iodometric method for copper, the addition of a solublethiocyanate near the end-point is claimed 73 to increase its sharpnessand accuracy, whilst the adsorption of starch iodide by the precipit-ated cuprous salt is said t o be reduced by the addition of a solutionof white shellac in alcohol. 74Of all methods for the determination of an element, those ofMarsh and Gutzeit must, in the past, have received as much attentionas, if not more than, any other single method, and fresh contributionshave again been made during the year.In describing modifiedapparatus and technique for the Marsh-Liebig method, G . Locke-mitnn 75 points out that the customary hard-glass Kjeldahl flaskmay yield small amounts of arsenic, and recommends silica flasks intheir stead. W. Deckert,76 however, states that this dissolutionof arsenic is appreciable only on the first occasion such a flask isused, but Lockemann maintains his objection.77 Further, whenmercury is present, satisfactory arsenic mirrors are said to beunobtainable.78 Other modifications of the Marsh 79 and theGutzeit *O method have also been detailed.Methods for tin which do not depend on its reducing power arestill all too few, and a much-needed organic reagent which will dofor the determination of quadrivalent tin what the oximes havedone for that of nickel, still awaits discovery.In alkali molybdates, molybdenum is determined as the silversalt,*l and it can be precipitated as the 8-hydroxyquinoline deriv-ative, MoO2(C9H6ON),, without disturbance due to the presence of aphosphate.8272 P.R. Ray and J. Gupta, Mikrochem., 1935,17, 14; A., 318.73 H. W. Foote and J. E. Vance, J . Amer. Chem. SOC., 1935, 57, 845; A.,837.74 J. R. Caldwell, ibid., p. 96; A., 318; cf. A. D. Mitchell and A. M.Ward, “ Modern Methods in Quantitative Chemical Analysis,” 1932,p. 67.75 Angew. Chem., 1936, 48, 199; A., 596; 2. anal. Chem., 1935, 100, 20;A., 554.76 Ibid., 101, 338; A., 948.7 7 Ibid., p. 340; A., 948.78 H. Kiihl and B. Czyiewsky, Pharm. Zentr., 1934,75,660; A,, 1934, 1322.79 J.Gangl, Oesterr. Chem.-Ztg., 1935, 38, 64; A., 718.80 L. W. Strock, 2. anal. Chem., 1934,99,321; A., 1935,184; J. D. Gnessin,Pharm. Zentr., 1934, 75, 719; A., 1935, 53; cf. also R. Steinbriick, ibid., 1935,76, 5 ; A., 184; C. J. Snijders, jun., and A. J. W. van der Drift, Chem. Week-blad, 1935, 32, 275; A., 718.81 L. W. McCay, J . Amer. Chem. SOC., 1934,56,2548 ; A., 1935, 187.82 S. Ishimaru, J . Chem. SOC. Japan, 1934, 55, 732; A., 1935, 56460 ANALYTICAL CHEMISTRY.With material containing elementary sulphur and selenium,sodium thiosulphate and thioselenate are formed by boiling with10% aqueous sodium sulphite, after which the selenium is precipit-ated by warming with f~rmaldehyde.~~ According to V. H~vorka,*~selenious acid is quantitatively reduced to selenium by acetone.saturated with sulphur dioxide.This author has also studied indetail the reduction by hydrazine and finds that a direct separationof selenium from cadmium, lead, vanadium, tungsten, etc., by thismeans is possible only under certain condition^.^^Pyridine precipitates tellurium from its tetrachloride as the di-oxide, which is weighed after drying a t 120°.86The micro-determination of platinum, iridium, and associatedpotassium and chlorine,87 and the volumetric determination ofrhenium with ferric sulphate, potassium dichromate and permangan-ate, or ceric sulphate, according to the nature of the compoundpresent,s8 are also described.In the third analytical group the use of 8-hydroxy-quinoline has been further applied to thorium,89 which is precipitatedas Th(CgH,0N)4,C,H,0N,90 and to z i r c o n i ~ m , ~ ~ after precipitationas Zr(C,H,ON),, which can be weighed directly, titrated withbromate, or ignited to ZrO,# According to other workers,92 however,the last compound and its bromine derivative are unsuitable forthe accurate determination of zirconium.The reagent has alsobeen used t o separate metals of this group from phosphate ions,which can then be determined in the usual ~ a y . ~ 3 In an importantpaper, H. B. Knowles 94gives the conditions necessary for the success-ful separation of aluminium and beryllium from many metals,using 8-hydroxyquinoline, and discusses the reasons for the some-what high results which the method gives.A procedure for de-termining aluminium in alloys which may contain iron, nickel,Group III.83 E. Cheraskova and L. Veissbruth, 2. anal. Chem., 1935, 102, 353; A.,84 Chem. Listy, 1935, 29, 73; A., 718.6 5 Coil. Czech. Chem. Comm., 1935, 7, 182; A., 948.6 6 A. Jilek and J. KO€&, ibid., 1934, 6, 398; A., 1934, 1322.8 7 H. D. K. Drew, H. J. Tress, and G. H. Wyatt, J., 1934, 1787; A., 1935,68 W. Geilmann and W. Wrigge, 2. anorg. Chem., 1935,222, 56; A., 464.8u F. Hecht and W. Ehrmann, 2. anal. Chem., 1935,100,98; A., 464.*O Cf. F. J. Frere, J . Amer. Chem. SOC., 1933, 55, 4362; A., 1934, 82.91 G. Balanescu, 2. anal. Chem., 1935, 101, 101; A., 721.92 P. Sue and G. W6troff, Bull. SOC. chim., 1935, [v], 2, 1002; A., 989.83 S.Ishimaru, J . Chem. SOC. Japan, 1935, 56, 62; A., 1337; see also84 J . Res. Nat. Bur. Stand., 1935, 15, 87; A., 1216.1336.56.ref. 82THEOBALD : INORGANIC ANALYSIS. 461molybdenum, etc., has also been de~cribed.9~ Finally, the bluish-black precipitate, ( CgH60N)4V20,, which is obtained with S-hydroxy-quinoline and a vanadate in presence of acetic acid, has beenutilised for the gravimetric determination of vanadium.96Vanadous ammonium sulphate, VS04,(NH,),S0,,6H,0, whichis more stable in air than VSO,, is another reagent which has beenapplied to this group in volumetric method8 for ferric iron andchromium as chromate.97 The conditions under which cupferronmay be used to determine copper, ferrous and ferric iroq98 and alsomicro-quantities of aluminium in plant material by a nephelo-metric methodYQ9 have been investigated.The B.P.(1932) method for determining metallic iron in the pre-sence of iron oxides is stated to give results which are inaccurateand variable, and a modification of Wilner’s method is preferred.Micro-methods for iron consist of reduction of a hydrochloric acidsolution by passage through a silver sponge reductor, followed bytitration with 0~002-0~015N-ceric sulphate, using ad-dipyridylas indicator,3 or reduction with electrolytic cadmium (zinc beingless trustworthy in a micro-reductor), followed by titration withO.005.N-permanganate using cyanin-B or erioglaucin-A as indicator .4Pyridine, according to P. S p a c ~ , ~ will separate iron completely asFe( OH), from solutions containing ferric iron and cobalt, whichcan then be determined as [CO(C~H~N)~(CNS)J in the remainingsolution.Contrary to all accepted procedure6 are the findings’ thatzirconium should be precipitated in sulphuric acid which is not moreconcentrated than 1%, and that titanium must first be eliminatedin the phosphate method for the determination of small quantities95 T.Heczko, Chem.-Ztg., 1934, 58, 1032; A., 1935, 187.96 R. Montequi and M. Gallego, Anal. Pis. Quim., 1934, 32, 134; A., 1935,9 7 P. C. Banerjee, J . Indian. Chem. Soc., 1935,12, 198; A., 838.s * E. Benedetti, Rev. Fac. Cienc. quim., La Plata, 1934,9,59; A., 1935, 720.93 P. Meunier, Compt. rend., 1934,199, 1250; A., 1935, 186.1 F. Hartley, W. H. Linnell, F. E.Read, and H. G. Rolfe, Quart. J . Pharm.,2 E. Merck, 2. anal. Chern., 1902, 41, 710.8 C. J. van Nieuwenburg and (Miss) H. B. Blumendal, Mikrochem., 1935,18,4 J. Knop and 0. Kubelkovci, 2. anal. Chem., 1935,100,161 ; A., 464.6 Compt. rend., 1935, 200, 1595; A., 838.6 see W. F. Hillebrand “ The Analysis of Silicate and Carbonate Rocks,”U.S. Geol. Survey, 1929, Bull. No. 700, p. 173; W. F. Hillebrand and G. E. F.Lundell, ~ p . cit., p. 446.7 V. A. Oschman and T. K. Zertschaninova, RedE. Met., 1934, 3, No. 6, 36;464.1935, 8,100; A., 720.39; A., 1095.A., 1935, 1339462 AN&Y TICAL CHEMISTRY.of zirconium in rocks. This latter element is also determined bymeans of n-propylarsonic acid,8 whilst thorium is determined onboth macro- and micro-scales by means of picrolonic acid.8The precipitation of aluminium alone from a mixture containingaluminium, manganese, nickel, and cobalt by hexamethylene-tetramine lo revives interest 11 in the possibilities of a more ex-tended use of this reagent which appears to possess certain advant-ages.Volumetric methods for aluminium,12 beryllium,13 chromium(micro),14 as well as a gravimetric method for beryllium,15 have alsobeen put forward. The solubility of strongly-ignited chromiumsesquioxide in warm, dilute solutions of potassium bromate, wherebychromate is formed, is an unexpected reaction which is of interest.lsAfter reduction to the quadrivalent state, vanadium is precipit-ated by ammonium benzoate as VO(OBz), which can be ignitedto the pentoxide; iron and chromium should be absent, but mag-nesium, aluminium, titanium, and some other metals are said notto interfere.17 Alternatively, the precipitate of [CO(NH3),],(V,01,)3,formed in acid solution with VO,' and Co(NH,),'", can be used forthe quantitative separation of vanadium from iron, phosphate,arsenate, etc., but not from tungstate, molybdate, or lead.l* Forthe volumetric determination of vanadium, A.J. Berry l9 appliesthe iodine cyanide method to the oxidation of VII to P I .W. R. Schoeller and his co-workers make further contributionsto the analytical chemistry of tantalum and niobium in dealingwith the separation of the rare earths from the earth acids20 andtungsten from titanium, niobium , tantalum, and zirconium .21F.W. Arnold, jun., and G. C. Chandlee, J. Amer. Chem. SOC., 1935,57, 8;F. Hecht and W. Ehrmann, 2. anal. Chem., 1935,100, 87; A., 464.A., 319; G. C . Chandlee, ibid., p. 591; A., 598.lo T. KGzu, J . Chem. SOC. Japan, 1935, 56,22; A., 1338.l1 Cf. C. Kollo and N. Georgian, Bul. SOC. Chim. Rodnia, 1924,6, 111 ; A.,1925, ii, 330; P. Ray and A. K. Chattopadhya, 2. anorg. Chem., 1928,169,99;A., 1928, 387; V. F. Stefanovski, J. Appl. Chem. Ru&a, 1934, 7, 1288; A.,1935, 318.l2 M. K. Bachmutova, Legk. Metal., 1934, 3, No. 9, 37; A., 1935, 1338.l3 B. S. Evans, Analyst, 1935, 60, 291; A., 837.l4 D. Brard, Ann. Chim. analyt., 1935, [iii], 17, 201, 257; A., 1095, 1339.l6 I. Iitaka, Y. Aoki, and T. Yamanobe, Bull. Inst. Phy8. Chem. Res. Tokyo,l6 R.Lyden, 2. anorg. Chem., 1935, 223, 28; A., 834.l7 F. M. Schemjakin, Zavod. Lab., 1934, 3, 986; A., 1935, 319; F. M.SchemjakinandV. F. Tschapigin, J. Appl. Chem. Rwsia, 1935,8,536 ; A., 1095.lS W. G. Parks and H. J. Prebluda, J. Amer. Chem. Soc., 1935,67,1676 ; A.,1339.lo Analyst, 1934, 59, 736; A., 1935, 56.llo W. R. Schoeller and E. F. Waterhouse, ibid., 1935, 80, 284; A., 838.21 A. R. Powell, W. R. Schoeller, and C. Jahn, ibid., p. 506; A., 1217.1935,14, 741 ; A., 1216THEOBALD : INORGANIC ANALYSIS. 463J. A. Tschernichov and M. P. Karssajevskaja 22 find that, contraryto previous statements, niobium cannot be accurately determinedby reduction with zinc amalgam and re-oxidation with standardferric chloride.a-Nitro- @-naphthol in acetic acid solution precipitates cobalt asCO(C~~H,ON~,),,~~ and in a suitable concentration of acid a quanti-tative separation from aluminium, chromium, nickel, and zinccan be obtained.I f iron is first removed with zinc oxide, the methodcan be applied to cobalt steels.24 In the well-known or-nitroso-p-naphthol method, C. H. Damon 25 advises the replacement of ammon-ium chloride and hydrochloric acid by sodium sulphate and aceticacid, respectively. A. Tauring,, determines this metal as a newcomplex, [Co(NH,),][HgI,],, by precipitation in an atmosphereof carbon dioxide with K,Hg14 from strongly ammoniacal solution,but the oxidation of the precipitate in air may restrict the popularityof the method.Quantitative separations of metallic sulphates such as those ofcobalt from nickel, iron from titanium, aluminium, zinc, or mangan-ese, etc., can, according to L.Wohler and K. be effectedby selective dissociation in a current of sulphur trioxide or the di-oxide and oxygen at suitable temperatures, and the method has beenused for the quantitative isolation of aluminium, iron, and titaniumfrom bauxite.A volumetric method involving precipitation of cobalt with am-monium thiocyanate and pyridine and titration of the excess CNS’ion by silver nitrate appears to have been put forward more or lesssimultaneously by two independent groups of investigators.28The solubility of nickel dimethylglyoxime 29 in hot solutionsstill seems to be disregarded. That this source of error is a realone can easily be checked, e.g., in a nickel steel analysis a milligramor so of the nickel compound will always separate out on coolinga solution which has been filtered hot and washed with hot insteadof cold water.The interference to which this method is subjectin presence of large amounts of copper can be overcome by the22 2. awl. Chem., 1934, 99, 398; A., 1935, 721; cf. V. Schwam, Angew.Chem., 1934,47,228 ; A., 1934, 622.23 H. Herfeld and 0. Gerngross, 2. anal. Chem., 1933, 94, 7 ; A., 1933, 1025.24 C. Map, ibid., 1934, 98, 402; A., 1934, 1324.26 J . Chem. Educ., 1935,12, 193; A., 1072.26 2. anal. ChRrn., 1935, 101, 357 ; A., 951.27 Ber., 1934,67, [B], 1679; A., 1934, 1320.28 J. T. Dobbins and J. P. Sanders, I d . Eng. Chem. (Anal.), 1934, 6,459; A., 1935, 56; G.Spacu and M. Kuraii, Bul. SOC. gtiinte Cluj, 1934, 7,377; A , , 1934, 1323.29 P. Nuka, 2. anal. Chem., 1933, 91, 29; A,, 1933, 138464 ANALYTICAL CHEMISTRY.addition of sodium hyposulphite prior to that of the oxime, and themethod is then said to be particularly applicable to the analysisof nickel-copper alloys.30 For those who prefer a volumetricending to a determination, there is now available, in addition to thetitration of the acid liberated by the reaction between nickel anddimethylglyoxime,31 another method,32 which determines, by meansof ferric sulphate and permanganate, the hydroxylamine liberatedwhen the nickel dimethylglyoxime is hydrolysed by boiling withdilute sulphuric acid. This method also is applicable to thedetermination of nickel in steels and coinage alloys when tartaricacid is present.The compound of copper with salicylaldoxime canbe treated in a similar way.Zinc in the presence of various metals is determined on bothmacro- 33 and micro-scales 34 by means of quinaldinic acid, whilst,according to C. Cimeran and P. Wenger,35 the method of H. Funkand M. Ditt,36 which uses anthranilic acid, is also suitable for micro-chemical work. A point of interest in connexion with the standardphosphate method for zinc is that decomposition of zinc ammoniumphosphate to the pyrophosphate begins a t 350" and is completein 90 minutes at 520°.37Group IV. The determination of the alkaline earths as oxdatescontinues to receive attention, and the behaviour of these oxalates,alone and together, when precipitated and washed by J.Dick'smethod,3s has been further in~estigated.~~ For calcium, titrationof the oxalate ion is preferable to weighing, but for barium, owingto the incompleteness of precipitation, and strontium the methodappears to be unsatisfactory. Magnesium, which is thrown downas the dihydrate, is likely to be co-precipitated with the calcium,so a double precipitation is necessary in this case. Barium andstrontium, when present, also interfere with the determination ofcalcium. H. Sibelius 4O considers that the determination of calciumas CaC,0,,H20 following 0. Brunck's directions *l is trustworthy.30 J. Ranedo, Anal. Pis. Quim., 1934, 32, 611; A,, 1935, 951.31 J. Holluta, Monatsh., 1919, 40, 281 ; A., 1920, ii, 57.32 B.Tougarinoff, Ann. SOC. Sci. Bruxelles, 1934,54, [B], 314; A., 1935, 187.33 P. Ray and A. K. Majundnr, 2. anal. Chem., 1935,100, 324; A., 597.3* P. R. R&y and M. K. Bose, Mikrochem., 1935, 17, 11; 18, 89; A., 318,35 Ibid., p. 53; A., 1094.38 Z..anal. Chern., 1933, 91, 332; A., 1933, 244.37 Z.H. PanandC.H. Chiang, J . Chinese Chem. SOC., 1935,3,118; A., 1093.38 2. anal. Chem., 1929, 77, 352; A., 1929, 901.39 J. Haslam, Analyst, 1935, 60, 668; A., 1338.40 Suornen Kem., 1935,8, [A], 25; A., 596.41 Z . anal. Chem., 1933,94, 81; A,, 1933, 1024.1094THEOBALD : INORGAN10 ANALYSIS. 465According to A. Ie~inTi,~~ ignition of calcium carbonate or oxalateover a gas flame yields an oxide containing SO4", and electricheating should therefore be employed.Although no data are recorded, N.A. Tananaev43 states thatcalcium and magnesium can be quantitatively extracted from bariumand strontium by treatment of the dry nitrates with glacial aceticacid. If this be true, then this acid could with obvious advantagereplace the fuming nitric acid which is used in S. G. Rawson'smethod 44 for the separation of calcium and strontium.A volumetric micro-method for calcium 45 consists in the titrationof exces8 picrolonate against methylene-blue in presence of chloro-form, after removal of the metal by means of a, standard solutionof lithium picrolonate.Group V. The determination of magnesium as MgNH,P04,6H,0,often used on the micro-scale, gives, on the macro-scale, resultswhich compare favourably with those obtained by the pyro-phosphate method.46 The 8-hydroxyquinoline method has beenfurther studied,*' and volumetric determinations include a methodfor the precipitation of the magnesium as MgNH,AsO, andthen titration of the arsenious oxide after reduction with sulphurdioxide .48No finality has yet been reached in the cobaltinitrite methodfor potassium. Each year sees its quota of papers on this subject.Different investigators seem able to evolve a method which satis-fies their particular requirements, but no agreement on a standardprocedure which will cover a wide range of concentration and con-ditions has been attained.The main difficulty still lies in achievingconstancy of composition of the precipitate produced.H. W.Lohse 49 states that this varies between KN~,[CO(NO,)~] andK,Na[Co(NO,),] according to conditions of precipitation, whilstC. S. Piper,50 in an examination of modifications necessary to ensurequantitative recovery over the range 0.1-50 mg. K20, finds that4 2 Latvij. Univ. Raksti, 1935, 2, 465; A., 1338.43 8. anal. Chem., 1935,100, 391; A . , 719.44 J . SOC. Chem. Id., 1897,16, 113; A., 1898, ii, 190; cf. W. Noll, 2. anorg.4 5 A. Bolliger, Austral. J. Exp. Biol., 1935, 13, 75; A., 1093.46 J. P. Mehlig, J. Chem. Educ., 1935, 12, 288; A., 1093; see F . P. Tread-well and W. T. Hall, op. cit., 1935, p. 81.4 7 M. Javillier and J. Lavollay, Bull. SOC. Chim. biol., 1934, 16, 1531 ; A.,1935, 186; D. C. Vucetich, Rev.B'ac. Cienc. qukm., La Plata, 1934, 9, 81 ; A.,1935, 719; G. Creuss-Callaghan, Biochem. J., 1935, 29, 1081; A., 837.Chem., 1931, 199, 193; A., 1931, 1259.4 8 W. Daubner, Angew. Chem., 1935,48,551; A., 1216.49 Id. Eng. Chem. (Anal.), 1935, 7, 272; A., 1093.50 J. SOC. Chem. Id., 1934, 53, 3 9 2 ~ ; A., 1935, 317466 ANALYTICAL CHEMISTRY.the ratio of potassium to sodium in the precipitate varies accordingto the composition of solution and precipitant and to the conditionsof precipitation. Error may also be introduced by the presenceof ammonium salts in some brands of cobalt nitrate of reagentquality.51 Other workers 52 describe modified methods. C. Peng 53introduces a variation in the volumetric ending by decomposingthe cobaltinitrite (equivalent to < 20 mg.K20) with dilute hydro-chloric acid containing urea and titrating the excess of acid withalkali, whilst (Miss) H. Bennett and H. F. Harwood 54 improve itby utilising a cerimetric meth0d.5~ Finally, A. Bolliger 55 precipi-tates the potassium (0.0P-10 mg.) as picrate and titrates this witha standard methylene- blue solution .56The determination of sodium as sodium magnesium uranylacetate after removal of potassium, as perchlorate, and otherinterfering ions has also been des~ribed.~'R. W. Feldmann5* finds that the bismuth iodide method ofN. A. Tananaev and E. P. Harmasch59 gives inaccurate resultsfor the determination of cmium both in pure solutions of its saltsand in mixtures with rubidium.A mercurimetric method for the halogens, includingfluorine, is described in detail, and a precision equal to that of theclassical methods is claimed for it.60 For fluorine in small amount,B.Visintin's procedure 61 is adversely criticised.62 In the Volhardmethod for chloride, the addition of nitrobenzene eliminates thenecessity of removing the precipitated silver chloride. 63 Threemethods for the analysis of chlorides in the presence of thiocyanateshave also been examined.64 Volumetric micro-methods for chlor-Anions.61 J . SOC. Chem. Ind., 1935, 54, 157.1.; A , , 036.52 S. D. Sunawala and K. R. Krishnaswami, J . Indian Inst. Sci., 1934, 17,[A], 105; A., 1935, 54; K. Nownk, PrzemysZ Chem., 1934, 18,509; A., 1935.185.63 Trans. Sci. SOC. China, 1934, 8, No. 2, 153; Proc.Internat. Xoc. Soil Sci.,1935,10, 105; B., 966.Analyst, 1935, 60, 677; A., 1337.5 5 J . BioZ. Chem., 1934,107, 229; A., 1934, 1322.5 6 J . Proc. Roy. SOC. N.S.W., 1933, 67, 240; A., 1934, 1017.5 7 F. Kogler, Angew. Chem., 1935, 48, 561 ; A., 1215.5 8 2. anal. Chem., 1935, 102, 102; A . , 1215.59 Ibid., 1932, 89, 256; A., 1932, 1010.6O A. Ionescu-Matiu and S . Herscovici, Bull. SOC. chim., 1934, [v], 1, 1379;61 Ann. Chim. app?., 1934,24, 315; A., 1934, 980.62 M. Giordani, ibid., p. 496; A . , 1935, 53.G3 J. R. Caldwell and H. V. Moyer, Ind. Eng. Chem. (Anal.), 1935, 7 , 38;64 E. Cohen and K. Piepenbroek, 2. a w l . Chem., 1934, 99, 258; A., 1935,A., 1935, 183.A., 316.183THEOBALD : INORGANIC ANALYSIS. 467ide,65 bromide in the presence of a large excess of chloride,66 andbromide and iodide in the presence of chloride67 have been putforward, and the precautions necessary for accurate work with0-OW-iodine solutions have been defined.68 The loss of iodineby volatilisation from dilute iodine-potassium iodide solutions duringthe pctssage of air has been investigated by W.A. Hough and J. B.F i ~ k l e n , ~ ~ and a method for the determination of small quantitiesof iodides is described by M. L. Jean,70 who applies it also to silverand chromate.The best conditions for determining C10,' in the presence of variousinterfering ions have also been studied in detail,71 and M. L. Nichols 72discusses the reduction of chlorates and perchlorates by titanouschloride.Cyanates can be titrated with silver nitrate using fluorescein asadsorption indicator.73A review of methods used in the volumetric determination ofsulphates 74 has been made, as well as a study of the reactions whichoccur in the precipitation of Ba", Pb'., or SO," ions as bariumor lead ~ulphates.~~ A method for the removal of carbon dioxidein micro-determinations of alkali carbonates is also described.76In the determination of ferrocyanide by means of dichromate,a controlled acidity is essential; t8he application of the methodto the determination of zinc is discussed.77 Perricyanide, potassiumpermanganate, and, indirectly, iron can be titrated on a micro-scale by means of 0-001N-solutions of indigo-~armine.~~Conditions for the complete precipitation of silica by ammoniummolybdate have been studied; the silica in the precipitate can bedetermined gravimetrically, by titration with sodium hydroxideor by reduction and back-titration with ~ermanganate.'~66 B.Bullock and P. L. Kirk, Ind. Eng. Chem. (Anal.), 1935,7,178; A., 835.66 F. L. Hahn, Mikrochem., 1935,17, 282; A., 835.67 I. Bellucci, Cazzetta, 1934, 64, 688; A., 1934, 1321.613 J. Renaudin and (Mme.) Renaudin, J . Pharm. Chim., 1934, [viii], 20, 516 ;6s I d . Eng. Chem. (Anal.), 1934, 6, 460; A . , 1935, 52.70 Bull. SOC. chim., 1935, [v], 2,605; A., 717.71 C. Smeets, Natuurwetensch. Tijds., 1934,16, 262; A., 1935, 183.72 I d . Eng. Chem. (Anal.), 1935, 7, 39; A., 316.73 R. Ripan-Tilici, 2. anal. Chem., 1935, 102, 32; A . , 1093.74 G.A. Ampt, J . Proc. Austral. Chem. Inst., 1935, 2, 10; A . , 462.75 Z. Karaoglanov and B. Sagortschev, 2. anorg. Chem., 1935, 221, 369;713 J. Mika, 2. anal. Chem., 1935, 101, 270; A., 836.7 ' F. BurrielandF. Sierra, Anal. Pis. Quim., 1934,32, 87; A., 1935, 697.7 8 I. M. Korenman, Mikrochem., 1935,18, 31; A , , 1095.79 S . Kitajima, Bull. Chem. SOC. Japan, 1935, 10, 341; A., 1337.A., 1935, 184.A., 317468 ANALYTICAL CHEMISTRY.Various applications of titrations with alkaline permanganate,e.g., PO3”‘, CNS’, 103‘, CN’, etc., are described,SO and those ofFajans’s titration method are reviewed.81Misce1Zaneous.-The pH ranges for the precipitation of certainmetals by anthranilic acid are recorded by H. Got6,82 and J. G. 3’.Druce 83 reviews the use of magnesium perchlorate (“ anhydrone ”)as a desiccant.84Finally, in view of the steadily increasing use of perchloric acidin analytical work, the observation 85 that mixtures of aqueoussolutions of this acid and organic substances are liable to explode,even in the cold, has its interest.Qualitative.General Methods for the Detection of Anions and Cations.-Although much attention has been focussed on the newer methodsof defection of ions, the older, macro-methods have by no meansbeen neglected, and an account of some of this work during the pastyear will now be given.Numerous reactions, with their sensitivities, are recorded forthallium with a wide range of reagents,s6 and for the commonermembers of the second analytical group, with potassium iodide andvarious aromatic and cyclic bases.87 Tests for mercury dependon the formation of the complex ion HgI,‘’,s8 followed by reductionwith alkaline glycerol 89 or stannous chl~ride,~O or of gold chloride.91The change in colour to blue, which the green flame due to copperundergoes in presence of carbon tetrachloride, serves to distinguishthis element from other substances giving a green flame,92 and inview of the use of ct-benzoinoxime as a test for copper 93 the observ-81 E.J. Kocsis and L. PollAk, Acta Lit. Sci. Univ. Hung. Francisco-Joseph.,1934, 4, 147; A., 1935, 836; K. Fajans, in ‘‘ Die chemische Analyse,” vol.33, “ Neure massanalytische Methoden,” 1935, p. 161 et seq.82 J . Chem. SOC. Japan, 1934, 55, 1156; A., 1935, 720.a3 Chem.and Ind., 1935,54, 133; A., 321.8* See also W. F. Hillebrand and G. E. F. Lundell, op. cit., p. 45.8 5 J. R. Partington, Chem. and Ind., 1935, 54, 468; A., 715.S 6 J. C. Munch and J. C. Ward, J . Amer. Pharm. ASSOC., 1935,114,351 ; A., 950.8 7 I. M. Korenman, 2. anal. Chem., 1934,99,402; A., 1935,720.88 P. I. Trischin, J . Appl. Chem. Russia, 1934, 7, 1282; Ukrain. Chem. J.,1934, 9, 341 ; A., 1935, 318, 950.8O M. Schtschigol, J . Appl. Chem. Russia, 1935, 8,158; A., 950; Khim.Farm. Prom., 1934, No. 1, 44; A., 1934, 1323.So N. A. Tananaev, J . Appl. Chem. Russia, 1935,8,356; A., 950.O1 E. Stathis, 2. anal. Chem., 1934, 99, 106; A., 1935, 55.O2 P. Gabriel, Ind. Eng. Chem. (Anal.), 1934, 6, 420; A., 1935, 55.Q3 Feigl, ‘‘ Qualitative Analyse mit Hilfe von Tupfelreaktionen,” 1935, p.H.Stamm, Angew. Chem., 1934, 47, 791; A., 1935, 55.167THEOBALD : INORQANIC ANALYSIS. 469ation that nickel, platinum, and palladium form compounds withthis reagent 94 is of interest. Cadmium can be precipitated by theaddition of sodium selenide to the ammoniacal potassium cyanidesolution in presence of copper, nickel, cobalt, or zinc, thus avoidingthe doubt sometimes occasioned by the formation of rubianic acidin the usual group analysis. The test is sensitive to a few y.95Y. G. Popov 96 describes a test for this element in which it is claimedthat other metals do not interfere. A modified procedure for thearsenic sub-group has been worked and the colours produced bythe reducing action of mercurous chloride have been used to detectand estimate small amounts of arsenic, gold, platinum, palladium,selenium, tellurium, and iodine.98 In order to detect arsenic inpresence of antimony, N.A. Tananaev and V. D. Ponomarjevg9reduce its compounds to arsine by tin and hydrochloric acid, anti-mony yielding only the metal. Methods for the detection of smallquantities of germanium in presence of arsenic,l the separation of theplatinum metals by hydrogen under pressure,z and the detection ofsmall amounts of indium, gallium, and thallium, using q~inalizarin,~are also described.Changes in the benzoate method for the separation of iron,aluminium, and chromium 4 make it applicable to qualitativeanaly~is,~ and a slight modification of the usual phosphate separa-tion avoids coprecipitation of traces of zinc, cobalt, manganese,barium, and strontium.6 Suitable methods for the inclusion oftitanium and vanadium as an ordinary part of the third analyticalgroup are indicated.7The concentration of a precipitate at a liquid-liquid interfaceor in a non-miscible liquid is a device which is often of service inQ4 J.S. Jennings, E. Sharratt, and W. Wardlaw, J., 1935, 818; A., 981.s6 I?. Krumholz and 0. Kruh, Mikrochem., 1935,17,210; A., 837.96 Ukrain. Chem. J., 1934, 9, 307; A., 1935, 950.9 7 A. T. Lincoln and E. Olson, J . Chem. Educ., 1935, 12, 264; A., 1092.Q8 G. G. Pierson, Ind. Eng. Chem. (Anal.), 1934, 6, 437; A., 1935,53.2. anal. Chem., 1935,101, 183; A., S36.S. A. Coase, Analyst, 1934,59, 747; A., 1935,56.V.V. Ipatiev and V. G. Tronev, Cormpt. rend. Acad. Sci. U.R.S.S., 1935,E. Pietsch and W. Roman, 2. anorg. Chem., 1934, 220, 219; A., 1934,I. M. Kolthoff et al., J . Amer. Chem. Soc., 1934, 56, 812; A., 1934,2, 29 ; A., 951.1323.621.5 L. Lehrman and J. Kramer, ibid., p. 2648; A., 187.6 E. Kahane, Ann. Chim. analyt., 1935, [iii], 17, 119; A., 718.7 L. E. Porter, Ind. Eng. Chem. (Anal.), 1934, 6,448; A., 1935, 56; see alsoidem, ibid., p. 138; A., 1934, 502, concerning tungsten and molybdenum470 ANALYTICAL CHEMISTRY.analysis, and it is now used 8 to separate nickel dimethylglyoximefrom ferrous iron, and sulphur from certain sulphides, with iso-amyl alcohol.Na,[Hg(CNS)J is more sensitive than the corresponding potassiumand ammonium compounds as a reagent for ~ o b a l t . ~Methods for the detection of calcium in presence of barium andstrontium 10 and of potassium 11 are put forward.For the latter,zinc cobaltinitrite can replace the sodium salt when a test forsodium has subsequently to be made.l2 According to J. Gervinka,l3quinalizarin does not distinguish magnesium from barium, calcium,and strontium,14 whilst zinc, aluminium, and ferric iron interferewith the development of the colour reaction.A. P. Laurie 14u deals with small particles of insoluble materialby fusion with borax or microcosmic salt on a platinum wire andthen applies tests for the metals directly by immersion of the beadin appropriate reagents.A classification of anions is proposed by A.Hemmeler and M.Angelini,15 who discuss also the difficulties arising from the pre-sence of heavy metals. Among the new work on anions may be notedtests for fluoride ions,16 halides in presence of thiocyanates,17bromide and a systematic analysis of mixtures of thiocyanate andhalide iona,l8 traces of iodide in the presence of chlorates, bromates,and iodates ; 19 chlorate,20 sulphurous acid,21 thiosulphate,22 nitrate,23A. M. Belousov and A. G. Belousova, J . Appl. Chem. Russia, 1934, 7,837; A., 1935, 187.B. V. J. Cuvelier, 2. anal. Chem., 1935, 101, 108; A., 721.lo N. A. Tananaev, Ukrain. Chem. J., 1935,10,15 ; A., 949 ; 2. anal. Chem.,1935,100, 391; A., 719; E. R. Caley, Ind. Eng. Chem. (Anal.), 1934, 6, 445;A., 1935, 54.l1 B.Reichert, Arch. Pharm., 1935, 273, 232; A , , 596; C. N. Potschinok,J . Appl. Chem. Russia, 1935,8,524; A., 1093.l2 J. Adam, M. Hall, and W. F. Bailey, Ind. Eng. Chem. (Anal.), 1935, 7,310; A., 1337.l3 Chem. Listy, 1935, 29, 35 ; A., 1093.l4 Cf. Feigl, op. cit., p. 260.14a Analyst, 1934, 59, 746; A., 1935, 55.l5 Ind. chim., 1934, 9, 1343; A . , 1935, 317.l6 L. Kulberg, J . @en. Chem. Russia, 1934, 4, 1440; A., 1935, 717.l7 G. B. Heisig and L. K. Heisig, Ind. Eng. Chem. (Anal.), 1935, '7, 249; A.,l8 L. J. Curtman and H. Schneiderman, Rec. trav. chim., 1935, 54, 158; A,,lo A. Vassiliou, Praktika, 1933, 8, 324; A., 1935, 52.2o H. R. Offord, I&. Eng. Chem. (Anal.), 1935, 7,93; A., 594.21 H. Freytag, Ber., 1934, 6'7, [B], 1477; A., 1934, 1321; ibid., 1935, 68,22 A.Blanck, 2. anal. Chem., 1935,101,194; A., 836.23 P. G. Popov, Ulcrain. Chem. J., 1934,9,310; A., 1935, 948.1091.462.[B], 585; A., 718THEOBALD : INORGANIC ANALYSIS. 471nitrite,24 cyanide,25 ferricyanides in presence of ferrocyanides,26and chr0mates.~7M. Eitel28 has studied in some detail the colour reactions of nitratesand other oxidising agents with solutions of organic reagents,especially quhones, in concentrated sulphuric acid. Quinones notsubstituted in the nucleus give colour reactions with nitrate but notwith nitrite, and p-benzoquinone is very suitable in this respectfor solid substances. Diphenyleneglycine in concentrated sulphuricacid is, on the other hand, a sensitive reagent for nitrates in aqueoussolutions.Tests which involve inhibition of, or changes in, fluorescence areutilised for the detection of chlorine and bromine in air or gasmixtures,29 of hyposulphites and sulphoxylates and “ nascent ”hydrogen,3* and of nitrites.31In view of the importanceand increasing use of drop reactions, the so-called “spot ” tests,the work done on them during the current period is again32 sum-marked. These tests are finding many applications in mineralogy,petrology, and in both pure and applied chemistry, and when theyare used with discrimination and due regard to possible interferingions, they afford a valuable analytical weapon for attacking withease problems which could be solved by macro-methods often onlywith difficulty and much uncertainty.Unfortunately, there is atendency to regard some of these reactions as specific for a particularelement when such is not the case.Too frequently, in fact, thisclaim has been based on a survey insufficiently comprehensive tojustify it. These tests are particularly useful as confirmatory testsin an ordinary analysis after a group separation has been carried out,and they can deal very successfully with traces or small precipitateswhich so often are inclined to be troublesome in a qualitative analysis.In general, they are preferable to tests which depend on the form-ation and recognition of crystals under the microscope, in that theyare quicker and easier t o carry out, less susceptible to conditions,and much easier to interpret.Drop Reactions.-A.“ #pot ” Tests.24 L. R. Catalano, Riw. Min., 1931, 1, 16; A., 1935, 316; A. C. Bittencourt25 L. J. Curtman and S. M. Edmonds, Ind. Eng. Chem. (Anal.), 1935, 7,26 I. M. Korenman, 2. anal. Chem., 1935,101,417; A., 1095.27 L. R. Catalano, loc. cit., ref. (24).28 2. anal. Chem., 1934, 98, 227; A., 1934, 1322.29 H. Eichler, 2. anal. Chem., 1934, 99, 272 ; A., 1935, 183.3O Idem, ibid., p. 270; A., 1935, 184.31 Idem, ibid., 1935, 100, 183 ; A., 463.32 Cf. Ann. Reports, 1934, 31, 314.and A. Barreto, €301. Min. Agric., Rio de <Janeiro, 1935, 23, 7 ; B., 225.121 ; A., 596472 ANALYTICAL CHEMISTRY.Tests for bismuth with thiocarbamides and other organic sulphurcompounds are described and discussed.33 p-Aminophenol hydro-chloride is a sensitive reagent for copper and iron; other metalsare said not to interfere.= Copper is also detected by the formationof the lilac-coloured compound Z~H~(CNS),,CUH~(CNS)~.~~ Ina critical study of the cacotheline test for tin,36 attention is directedto the interferences which arise from the presence of many anionsand cations : the test is by no means specific.The reddish-browncoloration obtained with As111 and 8 -hy droxy -N- e thy1 tetrahydro-quinoline hydrochloride (kairin) and ferric chloride can detect6 X 10-lo g. of arsenic, but mercury, lead, and copper interfere.37A test for antimony in presence of a large excess of arsenic or tinis also des~ribed.3~ Whilst osmium reacts with thiourea only,ruthenium compounds react with this reagent and its N-alkyl or-aryl derivatives to give sensitive, blue to red, coloration^,^^ whichare suitable for drop reactions. A solution of strychnine in sul-phuric acid is applied to the detection of chromate or dichrmnateions 40 and of manganese.41Indium can be detected by means of alizarin or quinalizarin andammonia vapour, aluminium being suppressed by the addition ofsodium fluoride, and zinc, nickel, cobalt, manganese, and ironbeing removed from the coloured spot with potassium cyanide .42The catechol test for titanium43 is not specific, but its sensitive-ness (1 in 5 X lo6) makes it useful for identification after a separationhas been effected.44 E.Kahane 45 discusses G. Denigks's colour33 J. V, Dubskf, A. OBQE, and J. Trtilek, Mikrochem., 1935, 17, 332; A.,1096; 2.anal. Chem., 1935, 100, 408; A., 721 ; J. V. Dubskf and A. Ok&E,ClLem. Obzor, 1934, 9, 3 ; A., 1934, 1324; P. R$y and J. Gupta, J . IndianChem. SOC., 1935,12, 308; A., 1094.34 S. Augusti, Mikrochem., 1935, 17, 118; A., 837.35 L. M. Kulberg, J . Appl. Chenz. Russia, 1934, 7, 1079; A., 1935,36 I. L. Newell, J. B. Ficklen, and L. S. Maxfield, Ind. Eng. Chem. (Anal.),37 W. Reppmann, 2. anal. Chem., 1934, 99, 180; A., 1935, 184.38 G. Gutzeit, R. Weibel, and R. Duckert, Arch. Sci. phys. nut., 1934, [v],39 B. Steiger, Mikrochem., 1935, 16, 193 ; A,, 332.40 S. Augusti, ibid., 1935, 17, 17; A., 319.41 Idem, Ann. Chim. appl., 1934,24,535 ; A., 1935, 55.42 A. S. Komarovski and N. S. Poluektov, Mikrochem., 1935, 16, 227; A.,43 J.Piccard, Ber., 1909,42,4343; A., 1910, i, 67; A. Rosenheim, B. Raib-44 N. R. Pike, J. B. Ficklen, and I. L. Newell, Ber., 1935, 68, [B], 1023; A.,45 .4nn. Chirn. analyt., 1935, [iii], 1'7, 175; A., 951.318.1935, 7, 26; A., 319.16, Suppl., 62 ; A., 1935, 464.318.mann, and G. Schendel, 2. anorg. Chem., 1931, 196, 160; A., 1931, 446.9h1THEOBALD : INORGANIC ANALYSIS. 473reaction between manganese and formald~xime.~~ Naphthazarinis used for magne~ium.4~ The alkali hypoiodite test for this metalis disturbed by ammonium, aluminium, and other cations.4a Dropreactions for cesium are few in number, but another test, sensitiveto 0-25 x g. of Cs per cu. mm., depends on the formation of theblack compound Cs,Au2PtBrlz. Rubidium reacts only when pre-sent in certain concentrations, but the other alkali ions and ammon-ium do not interfere.49The application of these colour reactions to the detection of manyelements in minerals is described by J.A. Wat~on,~O and R. Jirkov-sky 51 applies the rhodanine base used by F. Feigl 52 to the estim-ation of traces of silver in galenites and flotation concentrates.Procedures are also given 53 for the detection of germanium in oresand minerals and in zinc residues. After micro-distillation as thetetrachloride, it is converted into the complex germanium molyb-date, which is caused to oxidise benzidine to benzidine-blue, amuch-used device in these tests. Certain reactions of germanicacid, e.g., with mannitol, etc., resemble those of boric acid, but areless sensitive.54 Directions for the detection of many anions aregiven by N.A. Tananaev and A. M. Schap~valenko.~~ Colourreactions for i0dide,~6 nitrite,57 elementary hydrogenperoxide,5Q and ferricyanide in presence of a large excess of ferro-cyanideY6O have also been described.By suitable modifications of the Mitscherlich procedure,61 and ofthe boric acid-alcohol flame reaction,62 0.002 mg. of phosphorusand 0.00076 mg. of boron, respectively, can be detected.46 Compt. r e d . , 1932,194, 895; A., 1932, 491.4 7 J. V. Dubsky and E. Wagner, Mikrochem., 1935, 17, 186; A., 837.48 S. Augusti, Ann. Chirn. appl., 1934,24,531; A., 1935,54. For referencessee F. Feigl, “ Qualitative Analyse mit Hilfe von Tiipfelreaktionen,” 1935,p. 259.49 E.S. Burkser and M. L. Kutschment, Mikrochem., 1935,18,18; A., 1093.Min. Mag., 1935, 24, 21; A., 596.61 Chem. Listy, 1935, 29, 133; A., 1093.52 2. anal. Chem., 1928, 74, 380; A., 1928, 1108.53 A. S. Komarovsky and N. S. Poluektov, Mikrochem., 1935, 18, 66; A.,64 N. S. Poluektov, ibid., p. 48 ; A., 1095.6 5 J . Appl. Chem. Russia, 1934,7, 1258; A., 1935, 316.56 S. Augusti, Mikrochem., 1935,17, 113 ; A,, 836.5 7 H. Eichler, 2. anal. Chem., 1935, 100, 183; A., 463.6 8 A. Schonberg, Nature, 1934,134,628; A,, 1934, 1321 ; A. Schonberg andW. Urban, Ber., 1934, 67, [B], 1999; A., 1935, 184.5B E. Plank, 2. anal. Chem., 1934, 99, 105; A,, 1935, 52.60 E. Storfer, Mikrochem., 1935,17, 170; A., 838.61 R. Gros, J . Pharm. Chim., 1935, [viii], 22, 211; A., 1215.62 W.Stahl, 2. anal. Chem., 1935,101,342, 348; A., 949.1095474 ANALYTICAL CHEMISTRY.In the tests which have been mentioned, the limiting amountof an element or ion which can be detected is of the order ofg. or less, and in practically all of them the presence of otherconstituents necessitates a modified procedure with a resultant lossof sensitivity. For these details, however, the original literaturemust be consulted.B. Drop reactions involving the recognition of crystalline precipit -ates under the microscope. The Behren's tests. This line of workcontinues to be developed. The characteristic crystals formed whenpicric acid is added to salts of sodium, potassium, ammonium,barium, calcium, magnesium, beryllium, and other metals are de-scribed.63 Crystals of Zn[Hg(CNS)4] are used for the detection ofand those formed with 2-aminopyridine and sodiumbromide or potassium iodide are used for gold, bismuth, and anti-m ~ n y .~ ~ In a detailed examination, W. F. Whitmore and H.Schneider 66 describe the behaviour of the platinum group and goldwith various reagents and select the most characteristic tests. Theyalso give details for the qualitative analysis of the group as a whole.Rhodium yields 'a yellow crystalline precipitate with ammoniummercuric thiocyanate which serves for its identifi~ation,~' and 1 yoof cobalt in nickel can be detected by means of pyramidone andammonium thiocyanate which form characteristic precipitatesalso with cadmium, cobalt, and some other metals, but not withnickel.68 Ammonium molybdate can be employed as a micro-chemical reagent for cerium, aluminium, and certain other elements .69The detection of hydrogen cyanide by means of its catalysis ofthe alloxan-ammonia reaction 7O has been further in~estigated.~lFinally, E.M. Chamot and R. W. Brickenkamp 72 have describedthe characteristic crystalline precipitates which the polythionicacids form with benzyl-+-thiocarbamide, nitron sulphate, etc.,and have outlined a scheme for the identification of the oxy-acidsof sulphur.Books.-A new edition, revised and enlarged by W. T. Hall,of Volume I1 (" Quantitative Analysis ") of Treadwell and Hall's63 C. Frangopol, Bul. SOC. Chirn. Rorndnia, 1934, 37, 259; A., 1935, 949.6 1 I.M. Korenman, Mikrochem., 1935, 16, 223; A., 318.6 5 A. SB, Anal. Parm. Bioquim., 1934, 5, 3; A., 1935, 838.O 6 Mikrochem., 1935, 17, 279; A., 1096.67 A. Martini, Mikrochem., 1935, 16, 233; A., 319.6 8 Idem, ibid.69 C. van Zijp, Pharm. Weekblad, 1935, 72, 414; A., 720.70 G. DenigBs, Mikrochem., 1926, 4, 149; A., 1926, 1222.71 M. T. Koslovski and A. J. Penner, Arch. Pharm., 1934, 272, 792; A.,l2 Mikrochem., 1935, 16, 121; A., 316.1935, 54WEST : ORGANIC ANALYSIS. 475text-book has recently been published. The many changes in thetext have necessitated a resetting of the entire work.A second edition of Feigl’s “ Qualitative Analyse mit Hilfe vonTupfelreaktionen,” which rapidly established itself as a standardwork, also appeared in 1935.Additional tests for the metals havebeen included, but the chief feature of the new edition is a sectionwhich deals with the application of ‘‘ spot ” tests to organic analysis.Sutton’s “ Systematic Handbook of Volumetric Analysis ”(Churchill) has been thoroughly revised and brought up to dateby A. D. Mitchell. L. S. T.ORGANIC ANALYSIS.Modifications and improvements have been suggested for thedetection of elements by sodium fusion,l the Stepanov2 and theter Meulen3 method of organic analysis, and the rapid determin-ation of carbon by the wet oxidation method.*The following reagents have been investigated for the identi-fication of aldehydes and ketones : o-~hloro-,~ p-chloro-,6 3-nitro-,’and p-nitro-benzhydrazide,8 and o-tolylsemicarbazide.9 p-Chloro-benzazide has been investigated as a reagent for the identificationof primary and secondary amines, whilst 2 : 4 : 6-trinitrobenzoylchloride,ll o-nitro-, m-nitro-, and 3 : 5-dinitro-phenylcarbimides l2have been investigated as reagents for alcohols.Mixtures of aromatic nitro-compounds may be rapidly identifiedby optical crystallographic methods.13 The crystallographic datafor 20 nitro-compounds are described.The violet-red colour given by a solution of iodine and tanninwhen poured into a solution of an electrolyte is not due to liberatediodine, as it is also given when the iodine is replaced by chlorineor bromine .14C. L.Tseng, J . Chinese Chem. SOC., 1935,3,33, 122; A., 876, 1140.C. L. Tseng, M. Hu, and M. C. Chiang, ibid., p.223; A., 1258.J. Gauthier, Bull. SOC. chim., 1935, [v], 2, 322 ; A., 506.C. B. Pollard and W. T. Forsee, Ind. Eng. Chem. (Anal.), 1935, 7, 77;T. H. Sun and P. P. T. Sah, Sci. Rep. Nut. Tsing Hua Univ., 1934, 2,C. Shih and P. P. T. Sah, ibid., p. 353; A., 1934, 1376. ’ K. C. Meng and P. P. T. Sah, ibid., p. 347; A., 1934, 1376.P. Chen, J . Chinese Chem. SOC., 1935, 3, 251; A., 1259.H. H. Lei, P. P. T. Sah, and C. Shih, ibid., p. 246; A., 1259.lo C. Kao, H. Fan, and P. P. T. Sah, ibid., p. 137; A., 1117.l1 M. C. Chang and C. H. Kao, ibid., p. 256; A., 1259.l2 F. Hoeke, Rec. trav. chim., 1935, 54, 505; A., 958.l3 E. S. Davies and N. H. Hartshorno, J., 1934, 1830; A., 1935, 102.l4 F. Allegri, Boll. chim.-farm., 1935, 74, 555; A., 1244.A., 369.359; A., 1934, 1376476 ANALYTICAL CHEMISTRY.Quantitative.-. organic substance may conveniently be estim -ated by oxidation in 80% sulphuric acid solution by means of aknown volume of standard aqueous potassium dichromate solutionthe excess of which is determined i0dometrically.1~ The iodinevalues of unsaturated hydrocarbons have been determined by thedirect action of bromine vapour.16 The reaction is complete in10 minutes, and may be used as a microchemical method.1’2 : 4-Dinitrophenylhydrazine has been investigated as a reagent forthe determination of carbonyl compounds.lsThe methods available for the determination of amino-acidshave been reviewed,lg and numerous methods have been describedfor the determination of individual amino-acids and proteins.The difficulties experienced in the determination of the titratableamino-groups in proteins may be overcome by replacing the mineralacid by either metaphosphoric acid 2O or trichloroacetic acid.21Sugars, with the exception of rhamnose, may be quantitativelyprecipitated with methyl-alcoholic barium hydroxide solution ; 22they may be recovered from the precipitate by treatment with carbondioxide, and determined in the filtrate.Reduction of Fehling’ssolution by invert sugar, but not by glucose, is retarded by Na2HP0,and Na,P20, to an extent increasing with the duration of the re-action.23 The interference due to calcium in the volumetricFehling’s titration for invert sugar is eliminated by the additionof sodium he~ametaphosphate.~* An alkalimetric method for thedetermination of glucose is described,25 and is claimed to be moreaccurate than the methods ordinarily employed (0.05y0 error for0.1% solutions).By a method based on the oxidation of maltoseto maltobionic acid, this sugar may be estimated in the presenceof sucrose and monoses,26 and a method is described for the de-termination of fructose in the presence of glucose and S U C ~ O S ~ . ~ ~Colorimetry.-Colour reactions continue to attract considerableH. C. S. Snethlage, 2. anal. Chem., 1935,102, 321 ; A., 1390.E. Rossmann, Angew. Chem., 1935, 48, 223; A., 728.17 J. Boeseken and P. Pols, jun., Rec. traw. chim., 1935, 54, 162; A., 409.l8 G. W. Perkins and M. W. Edwards, Amer. J. Pharm., 1935,107,208 ; A.,l9 0.Furth, Sci. Pharm., 1934, 5, 21.2o R. K. Schofield, Trans. Paraday Soc., 1935, 31, 390; A., 300.21 R. K. Schofield and L. W. Samuel, Nature, 1934,134,665; A., 1934, 1375.22 T. Baba, Biochem. Z., 1935, 275, 253; A., 329.23 A. Malkov, J. Appl. Chem. Russia, 1934, 7, 1254; A., 1935, 329.24 J. G. N. Gaskin, Analyst, 1935, 60, 318; A., 964.2s E. N. Taran, J . Appl. Chem. Russia, 1935,8,562; A., 1108.26 E. Schapiro and M. N. Proferansowa, 2. Wirts. Zuclcerind., 1935,85, 196;2.7 M. Nordlund, Szcomen Kern., 1935,7, 95B; A., 1935, 68.998.A., 609WEST : ORGANIC ANALYSIS. 477attention, in general as specific tests for individual compounds.Such tests are too numerous to record here, but mention is madeof certain group reactions. The mono-, di-, and tri-nitro-derivativesof benzene yield with 5% potassium hydroxide solution in acetone,respectively, no colour, a blue, and a blood-red colour.28 Chloranilgives red, violet, and emerald-green colorations with primary,secondary, and tertiary amines, re~pectively.~~ Compounds con-taining CH, CH,, or CH, adjacent to a carbonyl group give red orbrown colours with slightly alkaline, alcoholic picric a~id,~O whilstacetic acid and methyl ketones may be detected by the formationof indigo tin .31Colorimetric methods are described for the quantitative deter-mination of glycine in salicylic acid,33 reducing sugars,=total, residual, and polypeptide nitrogen and urea,35 polypeptidescontaining a glycyl unit with a free amino-gr~up,~~ t r y p t ~ p h a n , ~ ~cysteine and cystine,,8 nitro naphthalene^,^^ hydroxydimorphineY40esters of phytosterol and chole~terol,~~ citra1,42 histidine:,q ~ i n i n e , ~ , 45 and ~ r o b i l i n .~ ~Micro-methods.-The existing apparatus for micro-hydrogen-ation has been adapted, and, using 1-3 mg. of material, the28 R. W. Bost and F. Nicholson, Ind. Eng. Chem. (Anal.), 1935, 7, 190;2D J. Siradjian, Bull. Soc. chim., 1935, [v], 2, 623; A., 769.30 M. Goswami, A. Shaha, and B. Mukerjee, J. Indian Chem. Soc., 1934, 11,s1 F. Feigl, R. Zappert, and S. Vtisquez, Milerochem., 1935, 17, 165; A.,32 A. R. Patton, J . Biol. Chem., 1934, 108, 267; A., 1935, 370.33 J. E. Heesterman, Chem. Weekblad, 1935, 32, 463; A., 1259.34 G. A. Bravo, Boll. Ufl. Staz. Sperim.Ind. Pelli, 1935, 13, 81; A., 734.35 E. Herzfeld, Mikrochem., 1935, 17, 155; A., 1044.36 M. Polonovski, Compt. rend. SOC. Biol., 1935, 120, 28; A., 1390.37 S. Winkler, 2. physiol. Chem., 1934, 228, 5 0 ; A., 1934, 1376; T. Tomi-yama and S. Shigematsu, Proc. SOC. Exp. Biol. Med., 1934, 32, 446; A., 1935,877.38 K. Shinohara, J. Biol. Chem., 1935, 109, 665; 110, 263; A., 877;1110.39 B. P. Fedorov and A. A. Spriskov, J . Gen. Chem. Russia, 1935, 5, 450 ;A . , 1116.4O B. Drevon, J. Pharm. Chim., 1935, [viii], 22, 97; A., 1260.4 1 A. Heiduschka and H. Sommer, 2. Unters. Lebensm., 1935, 69, 75; A.,42 J. Bougault and E. Cattelain, J. Pharm. Chim., 1935, [viii], 21, 437; A.,43 G. Barac, Compt. rend. Soc. Biol., 1935, 118, 198; A., 370.44 G.DenigBs, Bull. SOC. Pharm. Bordeaux, 1934, 71, 251 ; A., 1935, 102.46 J. A. Sanchez, J. Pharm. Chim., 1935, [viii], 21, 24; A., 370.46 M. Royer, Compt. rend. SOC. Biol., 1934,117, 1240; A., 1935, 379.A., 877.773 ; A., 1935, 228.877.487.733478 ANALYTICAL CHEMISTRY.conditions for the comparisons of the velocity of hydrogenation ofdifferent parts of the molecule have been investigated?'Qualitative reactions for monosaccharides,48 formaldehyde,*9and nicotine 50 depend on the formation of organic derivativesand the subsequent determination of melting points under the micro-scope. Flavianic acid is recommended for the isolation and identi-fication of bases. The melting points and the crystallographicand optical characteristics are given for the flavianates of 35 bases,mostly of biological imp~rtance.~~ The characteristic reactionsfor antipyrine,52 pyramid~ne,~~ and certain organic acids 54 involvethe formation of crystalline precipitates with inorganic reagents.These crystals are distinguished under the microscope by their shapeand optical properties.Colorimetric tests have been describedfor certain compounds of biological interest, the Liebermann-Burchard reaction being extended to include thiophen, furan andderivatives? and carotene. 55Volumetric estimations involving the use of the micro-burettehave been described for a-keto-acids by the reduction in acidmedium of CeIV,56 for o-nitrophenols by means of methylene-blue,57 and for rt-butyric acid by an iodometric method.58 Sucrosehas been determined in as little as 5 mg.of solution by the directmeasurement of specific gravity and specific rotation,59 and thecarbonyl group may be determined by a method involving the useof a micro-gas burette.60Colorimetric methods have been employed for a variety of sub-stances of biological or pharmacological interest? for methyl alcohol,61and for small amounts of organic arsenic compounds in air.624 7 K. H. Slotta and E. Blanke, J. pr. Chem., 1935, [ii], 143, 3 ; A., 862.4 ~ 3 R. Fisher and W. Paulus, Arch. Pharm., 1935, 273, 83; A., 477.49 R. Fosse, P. de Graeve, and P. E. Thomas, Compt. rend., 1935,200,1450;50 R. Fischer and W. Paulus, Milcrochem., 1935, 17, 356; A., 1141.5 1 W. D. Langley and A. J. Albrecht, J . Biol.Chem., 1935, 108, 729; A.,52 M. Wagenaar, Phawn. Weekblad, 1935,72,642 ; A., 877.53 Idem, ibid., p. 612; A., 877.54 A. J. Steenhauer, ibid., p. 667; A,, 998.55 V. E. Levine, E. Richman, and G. E. Bien, Proc. SOC. Ezp. Biol. Med.,S6 C. Fromageot and P. Desnuelle, Biochem. Z., 1935,279, 174; A., 1223.5 7 A. Bolliger, J . Proc. Roy. SOC. N.S.W., 1934, 68, 51; A., 1935, 1141.58 L. Klinc, Biochem. Z . , 1934, 273, 1; A., 1934, 1331.59 R. Beutler, Mikrochem., 1935, 16, 133; A., 330.6o F. von Falkenhausen, 2. anal. Chem., 1934, 99, 241; A., 1935, 228.61 M. Nicloux, Bull. SOC. Chim. biol., 1935, 17, 194; A., 1044.62 M. JureEek, Coll. Czech. Chem. Comm., 1934, 6, 468; A., 1935, 101.A., 877.639.1934,31,582 ; A., 1934, 1376HOUGHTON : WATER ANALYSIS.479Apparatus.-Crucibles containing sintered-glass plates (SchottNo. 4) are attacked by alkali and may lose 2-3 mg. when used forweighing cuprous oxide in Allihn’s method for determining sugars.The difliculty is overcome by cleaning the crucible in successionwith dilute nitric acid, water, alcohol, and ether after use, weighingit, and allowing for theDuring distillation, “ bumping ” is prevented by the presencein the liquid of a sintered-glass disc, through which a stream ofair or carbon dioxide is passed.6* If two right-angled bends 10-15cm. apart are inserted between the inlet end and the condenserjacket of a Liebig condenser, increased turbulence of the vapourscauses more efficient condensation and fewer fractures occur.65Apparatus is described for the analysis of organic liquids by fractionaldistillation,66 the fractional distillation of small volumes of liq~ids,~’and the simple regulation of pressure during a vacuum distillation.68Suggested modifications of the Soxhlet apparatus enable quanti-tative extraction to be obtained,69 and an apparatus is describedin which the solvent vapour is condensed and allowed to passthrough the material at any desired temperature below the boilingpoint.‘0 R. W. W.WATER ANALYSIS.In the decade which has elapsed since water analysis last receivedmention in these reports, a very large volume of literature has ap-peared and it will only be possible here to detail some of the moreimportant chemical work. Concurrently, bacteriological methodshave also been improved, and the bacteriological examination isstill of paramount importance where the hygienic quality of thewater is under consideration.Various attempts have recently been made to devise some roughlyquantitative method of estimating the intensity of the taste andodour of water.The maximum dilution in which a taste or odouris still apparent is termed the “ threshold value,” and dilution isbest performed with water which has been completely deodorisedwith activated carbon.2 An alternative method of measurementis by means of the “ osmoscope,” in which definite dilutions of the63 P. Balavoine, Mitt. Lebensm. Hyg., 1935,25, 323 ; A., 599.64 M. Mattikow, Id. Eng. Chem. (Anal.), 1935, 7 , 136; A., 599.6 6 H. Schanz, Chem.-Ztg., 1935, 59, 458; A., 952.66 H.S . King, Proc. Nova Scotian Inst. Sci., 1934, 18, 272; A., 1935, 1098.6 7 W. Swimtoslawski, Rocz. Chem., 1934, 14, 614; A., 1935, 321.68 0. J. Schierholtz, I d . Eng. Chem. (Anal.), 1935, 7, 284; A., 1098.68 A. G. Kuhlmann, 2. Unters. Lebensm., 1935,69, 221 ; A., 724.‘O F. W. Neumann, Chem. Pabr., 1935,8,326; A., 1218.C. H. Spaulding, Amer. J . Public Health, 1931, 21, 1038.0. Gullans, J . Amer. Water Works ASSOC., 1933, 25, 974480 ANALYTICAL CHEMISTRY.odour with air may be arranged. The intensity of odour is thendenoted by the number of times (po) that the odour must be dilutedwith an equal volume of odourless air in order to reach the thresholdvalue .3The discovery that extremely minute quantities of phenols areliable to give rise to taste in chlorinated water has stressed the needfor accurate methods for their determination.J. R. Baylis4 hasbased a, method on the Gibbs indophenol test (blue coloration withquinone-chloroimides), the actual reagent employed being 2 : 6-dibromoquinone-chloroimide. The pB of the solution is an importantfactor and should not vary by more than 0.2 unit either way,so all test solutions must be highly buffered. By use of a suitabledistillation technique, the method is claimed to be capable of de-termining 1 part of phenol in 1000 million parts of water. Severalworkers have also employed colorimetric methods based on thecoupling of the phenol with diazotised p-nitroaniline. The methodis sensitive t o 0.05 part of phenol per million, although smaller con-centrations may be determined if the phenol is first concentratedby distillation.Attention has been paid to the o-tolidine method of determiningfree chlorine in water, and a study has been made of the possibleinterfering substances.Experiments 6 show that the formationof the yellow colour with the reagent is probably due to oxidationrather than chlorination, and that chloroamines may also producethe colour although more slowly (10-20 minutes) than chlorine.Nitrites and tervalent manganese or iron also give a yellow colourwith the reagent. Manganic salts do not interfere if previouslyreduced to the bivalent state by addition of a dilute solution ofhydrogen peroxide,6 or alternatively they may be removed bycoprecipitation with magnesium hydroxide.It is stated 8 that,although free chlorine and nitrite cannot co-exist for long in distilledwater, chloroamine and nitrite can exist simultaneously in neutral,but not in acid, solution.Interference of nitrite may be prevented by a preliminary treat-ment with hydrogen per~xide,~ or a suitable correction factor maya G. M. Fair and W. F. Wells, Water Works Eng., 1934, 87, 1051.4 J . Amer. Water Works ASSOC., 1928,19, 597.S. Hilpert and R. Gille, Angew. Chem., 1933, 46, 326; Nolte, Chem.-Ztg.,H. W. Adams and A. M. Buswell, J . Amer. Water Works ASSOC., 1933, 25,.R. D. Scott, ibid., 1934, 26, 634.D. Tarvizi, H. R. Todd, and A. M. Buswell, ibid., p. 1645.C. H. H. Harold, Ann. Report of Director of Water Examination, M .W.B.,1933, 57, 654; T. Folpmers, Chem. Weekblad, 1934, 31, 330; B., 1934, 606.1118.1934, p. 4HOUGHTON : WATXR ANALYSIS. 481be applied to the o-tolidine indication.’ The use of four times theconcentration of hydrochloric acid normally employed in the testprevents interference of ferric salts.10It is noteworthy that more than 0.2 part per million of freechlorine produces a pink coloration in the m-phenylenediaminetest for nitrites.11New tests for nitrites in water depend on the blue coloration pro-duced with neutral-red,12 and the yellow coloration with benzidine ; 13also on the orange coloration formed on boiling with 2 : 6-di-iodo-phenolsulphonate, and the red colour after boiling with catecholand then rendering alkaline.14In distilling off free ammonia from polluted waters, it has beenshown that addition of sodium carbonate before distillation maycause hydrolysis of organic nitrogenous compounds.It is thereforepreferable to substitute a phosphate buffer solution which main-tains a constant pE of 7-4 throughout the distillation. Theammonia is then recovered quantitatively and the hydrolyticaction is minimised.15It is still a fact that the methods available for the chemical exam-ination of the organic matter in waters are somewhat empirical.An attempt has been made by J. W. Haigh Johnson l6 to correlatethe “ oxygen absorbed ” and the “ albuminoid ammonia ” test bymeans of an “oxy-albuminoid” method. In this method, thesample, after removal of free ammonia, is refluxed with a standardalkaline permanganate solution for 30 minutes.Aliquot portionsare then taken, and the unreduced permanganate and the albumin-oid ammonia are determined. The oxygen absorbed from perman-ganate in this method is stated to be about four times that absorbedfrom acid permanganate, and is therefore in closer agreement withthe biological oxygen demand. Moreover, the albuminoid ammoniais quickly distilled and definite in amount.The urease method has now been applied to the determinationof urea in water, and a technique has been described by which0-004--0.200 mg. of urea may be determined. According to M. H.McCrady,l7 the present evidence indicates that urea in water isspecific proof of excretal pollution.10 R.D. Scott, J . Amer. Water Works ASSOC., 1934, 26, 1234.11 J. C. Herral and F. W. M. Jaff6, Analyst, 1932, 57, 308; B., 1932, 641.12 M. S. Vergnoux, Ann. China. analyt., 1929, 11, 366.13 G. Carpentier, Union Pharmaceut., 1932, 72, 162; Chern.-Zentr., 1932,14 A. Castiglioni, Bazzetta, 1932, 62, 1065; A,, 1933, 243.1 5 M. S. Nichols and M. E. Foote, Id. Eng. Chern. (Anal.), 1931, 3, 311.1 6 Analyst, 1927, 52, 130.17 J . Amer. Water Works ASSOC., 1930, 22, 926.[ii], 3761.REP.-VOL. XXxII. 482 ANaLYTICAL CHEMISTRY.The test for the biological oxygen demand of polluted waters hascontinued to receive attention, particularly in America. Thecharacter of the water used for dilution in the test is an importantfactor in obtaining concordant results.Current American prac-tice 18 employs distilled water which is buffered with 0.03% ofsodium bicarbonate and does not absorb more than 0.2 part permillion of dissolved oxygen in 5 days a t 20”. The pH of the sampleis best adjusted before dilution to fall between 6.5 and 9.0, and thedilution in which the oxygen has been depleted nearest to 60%of the original content is recommended l9 for the calculation of theoxygen demand.A rapid method for the estimation of dissolved oxygen is basedon the production of a reddish-brown colour with amidol. Solutionsof potassium citrate and of amidol are added to the sample in astoppered tube, and the colour is matched against permanentstandards prepared from solutions of cobalt chloride and potassiumdichromate.20G.W. Hewson and R. L1. Rees21 have applied the electrical“ dead-stop ” end-point method z2 to the titration of the smallamounts of iodine liberated when determining the dissolved oxygenin de-aerated waters by the Winkler method. For these low iodineconcentrations the starch-iodide end-point is not sufficientlysensitive. The electrical method depends on the fact that if twoplatinum electrodes having a small potential difference (15 mv.)are immersed in the solution during the thiosulphate titration,the cathode becomes completely polarised at the end-point and nocurrent then passes. A back titration technique is describedwhereby variations of iodine concentration equivalent to 0.001ml. of oxygen per litre may be detected.In the Winkler method for the determination of alkaline hydr-oxides in the presence of carbonate and sulphate, the precipitateof barium sulphate is liable t o cause considerable error by occludinghydroxide. The error is minimised if strontium chloride is usedin place of barium chloride,23 but the solution then requires boilingbefore subsidence and subsequent titration of the supernatantliquid.Various volumetric methods for the determination of sulphatel8 “Standard Methods for the Examination of Water and Sewage,”lo 6th Annual Report, Ohio Conference on Sewage Treatment, 1932, 61,Zo M.L. Isaacs and F. W. Gilcreas, Sewage Works’ J., 1935, 7,435 ; B., 928.2 l J . Xoc. Chern. Ind., 1935, 54, 254r; B., 832.22 C. W. Foulk and A. T. Bawden, J .Amer. Chern. SOC., 1926, 48,2045.23 W. C. Schroeder, Ind. Eng. Chern. (Anal.), 1933,5, 389; B., 1934,47.American Pub. Health ASSOC., 1933, p. 89.Appendix 111; see Water Pollution Research Abstract, 1934, No. 983HOUGHTON : WATER ANALYSIS. 483in water have been described in recent years and among these aremodifications of the well-known barium chromate method.24Alternatively, the sulphate may be precipitated with standardbarium chloride, excess of which is titrated with sulphuric acidusing sodium rhodizonate as internal indicat0r,~5 or with an alcohol-glycerol solution of potassium palmitate using phenolphthalein.26An approximate method has also been based on the reaction ofsulphate with a suspension of barium carbonate, the sodium car-bonate produced being tit~+ated.~' Volumetric methods of sulphatedetermination are especially valuable in the routine analysis ofboiler water, and a critical examination of the various methods 28indicates that the palmitate method is most suitable for thispurpose.According to L.A. Tha~er,~9 the colorimetric method of F.Dihnert and F. Wandenbulcke (Compt. rend., 1923, 176, 1478)for the determination of silica by conversion into silicomolybdateis inaccurate if appreciable amounts of iron or phosphate are pre-sent. In such cases a preliminary procedure is recommended inwhich iron is removed as ferric phosphate in acetic acid solutionand the excess phosphate is precipitated as calcium phosphate.The filtrate is then tested for silica by the colorimetric method.A survey of the methods of testing for traces of cyanides in waterhas shown30 that the best procedure is to distil it with tartaricacid (under reduced pressure if phenols, fatty acids, etc., are pre-sent) and then to examine the distillate.The Prussian-blue testis, of course, specific for cyanide in the absence of ferrocyanide,and it is recommended when the concentration of hydrogen cyanideis over 1 in 250,000. For lower concentrations, it is advisableto employ the nephelometric silver cyanide method or the colori-metric method based on the production of phenolphthalein from thephthalin in the presence of cyanide and a trace of copper. Neitherthe silver cyanide nor the phenolphthalein method is, however,specific.The determination of small quantities of fluoride in water hasrecently assumed prominence owing to the probable associationof fluorine with mottled tooth-enamel.For this purpose H. V.e* G. Nachtigall and F. Raeder, Arch. Hyg., 1928, 100, 31; R. Schmidt,2. anal. Chem., 1930,82,353.25 B. Paschke, 2. Unters. Lebensm., 1931, 62, 378; B., 1932, 50.26 P. Hamer, J . SOC. Chem. Id., 1935,54,250~ ; G. Ammer and H. Schmidtz,2 7 D. Northall-Laurie, Analyst, 1931, 56, 526 ; B., 1931, 909.28 H. Reichelt, Chem.-Ztg., 1934, 58, 871.29 Id. Eng. Chem. (Anal.), 1930, 2, 276; A., 1930, 1145.30 A. E. Childs and W. C. Ball, Analyst, 1935, 60, 294; B., 656.Vom Wasser, 1933, '7, 185484 ANALYTICAL CHEMISTRY.Churchil131 has employed the volumetric method in which thefluoride is converted into ferric fluoride by the addition of standardferric chloride solution, the excess of which is determined iodo-metrically.Several workers32 have also applied the de Boerzirconium-alizarinmonosulphonate reagent to this problem. Thereddish-violet colour produced by this reagent in acid solution isdischarged by traces of fluorine, and a technique has been describedby Barr and Thorogood whereby 5 parts of fluorine per millionmay be determined directly to within 0.1 part. Calcium, iron,sulphate, phosphate, and organic matter are, however, all apt tointerfere, and for greater accuracy it is preferable to distil the fluorineas silicon tetrafluoride and apply the test to the di~tillate,3~ or toemploy standards of similar composition to the sample.34 The testmay be made more delicate by the use of quinalizarin 35 or purpurin 36in place of alizarin.The quantity of iodide present in natural waters is usuallyextremely small, and it is necessary to employ very large samples(preferably 25-100 litres) for its determination. J. J. Hinman 37recommends that the solids obtained by evaporation should beignited, with precautions to avoid losing iodine, which is thenliberated by addition of nitrosylsulphuric acid, extracted withcarbon tetrachloride, andmatched against standards. I n Martindale’smethod,38 the iodide is extracted from the solids with 95% alcohol,and the iodine liberated with nitrous acid and matched in etherealsolution.A method for the determination of lead in waters containing iron,copper, and organic matter has been based on its adsorption oncalcium ~arbonate.~g Potassium cyanide is added, and the sampleshaken for an hour with the calcium carbonate, which is then filteredoff and dissolved. The solution is treated with ammonium per-sulphate to oxidise organic matter, iron is reduced with hydrazinedihydrochloride, and the lead then determined by the usual colori-metric (Winkler) method.The white precipitate produced by zinc with sodium diethyldi-31 Ind. Eng. Chem., 1931,23, 996.32 E. Elvove, U.S. Pub. Health Reports, 1933, 48, 1219; J. M. Sanchis,Ind. Eng. Chem. (Anal.), 1934,6,134; G. Barr and A. L. Thorogood, Analyst,1934, 59, 378.33 C. S. Boruffand G. B. Abbott, Id. Eng. Chem. (Anal.), 1933, 5, 236.3* Barn and Thorogood, loc. cit., ref. (32).8 5 0. M. Smith and H. A. Dutcher, ibid., 1934, 6, 61.36 I. M. Kolthoff and M. E. Stansby, ibid., p. 118.3 7 J . Amer. Water Works ASSOC., 1928, 19, 566.38 “ Extra Pharmacopczia,” 1929, Vol. 11, 424.39 J. F. Reith and J. de Beus, Chem. Weekblad, 1935, 32, 205 ; B., 527HOUGHTON : WATER ANALYSIS. 485thiocarbamate may be used for the turbidimetric determinationof traces of the metal in water.40 The reagent is stated to be assensitive as ferrocyanide.For the determination of very small quantities of silver (e.g.,in waters disinfected by oligodynamic action), the metal may bematched colorimetrically after addition of Rochelle salt and sodiumsulphide.41 In a further method 42 the silver is filtered off as iodidethrough a membrane of porosity lp, an aqueous solution of hydro-gen sulphide passed through the membrane, and the density ofthe resulting coloration of the membrane compared with standards.It is claimed that 0.0025 part of silver per million may be determinedin this way if sufficiently large samples are examined with a mem-brane of small area. It has, however, been maintained43 that theonly reliable method of determining the strength of an oligodynamicwater is by comparing its bactericidal action against a standardsilver solution prepared by shaking distilled water with silver oxide.It seems likely that the application of micro-methods to thechemical examination of water maywell offer considerable advantagesin certain cases. C. Urbach 44 has recently described various photo-metric micro-methods for the analysis of water. It is stated thatnitrates, nitrites, ammonia, magnesium, calcium, sulphate, phos-phate, silicate, lead, and iron may ad1 be determined in this way.G. U. H.G. U. HOUGHTON.L. S. THEOBALD.R. W. WEST.43 JV. R. G. Atkins, Analyst, 1935, 60, 400; B., 752.41 Chlorator-G.m.b.H., Swiss P., 171,766; Chem. Zentr., 1935, i, 3455.42 J. Just and A. Szniolis, Arch. Chim. Farm., 1935, 2, 170; A., 719.43 F. Eichbaum, Zentr. Bakt. Par., Abt,. I, 1932, 126, 152.44 Mikrochem., 1932,10, 483; 11, 37, 50; 1933,13, 31, 201; 1934,14, 189,198, 321, 331; 15, 207; B., 1932, 658; 1933, 494, 734; 1934, 430, 654, 1038

ISSN:0365-6217    

DOI:10.1039/AR9353200451

出版商:RSC    

年代:1935

数据来源: RSC

摘要:

INDEX OI? AUTHORS' NAMESABADIE, P., 46.Abbott, G. B., 484.Abel, E., 46, 49, 58, 105, 237.Abkin, A., 258.Achenbach, H., 151, 153.Adams, H. W., 480.Adams, J., 470.Adams, R., 246, 247, 333, 334.Adel, A., 80.Adkins, H., 251, 253.Aoschlimann, J. A., 423.Ageew, N. W., 173, 175.Agruss, M. S., 25, 52, 144, 147.Akano, R., 412.Alberti, E., 177, 205.Albrecht, A. J., 478.Alder, K., 314, 316, 323.Alichanian, A. I., 32, 34.Alichanov, A. I., 32, 34, 35.Allard, J., 318.Allegri, I?., 475.Allen, A. O., 100.Allen, J. S., 132.Allen, W. M., 410.Allison, F., 142.Allison, S. K., 194.Allport, N. L., 349.Allsopp, C. B., 124.Alocco, G., 38.Alten, F., 438.Altman, R. F. A., 422.Amaldi, E., 20, 24, 27, 28, 147.Amberg, C. fz., 214.Amdur,I., 45, 99.Ammer, G., 483.Ammon, R., 424.Ampt, G.A., 467.Ananthakrishnan, R., 65, 66.Anderson, A., 432.Anderson, C. C., 279.Anderson, J. A., 433.Anderson, J. T., 177.Anderson, K. D., 103.Anderson, L. C., 43, 47, 106.Anderson, T. F., 86.Andrkev, K. K., 101.Andress, K. R., 177, 205, 222.Andrews, D. H., 85, 89.Angeletti, A., 445.Angelini, M., 470.Angus, W. R., 62, G5.Anschiitz, L., 158.Antonov, L. I., 435.Anurjeva, V., 289.Aoki, N., 179.Aoki, Y., 462.Appel, H., 250, 280.Applebey, M. P., 41, 52, 149.Arbusov, B. A., 322.Armstrong, K. F., 362, 367.Arnfelt, H., 201.Arnold, F. W., jun., 462.Arnold, L. B., 93.Arvin, J. A., 267.Arzimovitsch, L., 28.Asahina, Y., 328, 369, 370.Aschan, O., 323.Ashdown, A.A., 254.Ashley, M. F., 73, 89.Askew, 3'. E., 407.Astbury, W. T., 238, 239, 240,Aston, F. W., 16, 17, 18, 45, 146.Aston, J. G., 84.Asundi, R. K., 63.,4tkins, W. R. G., 485.&4udrieth, L. F., 249.Auger, P., 27, 38.Augusti, S., 472, 473.-4ult, R. G., 278, 280.Ayliffe, S. H., 234.Aynsley, E. E., 100.241.Baba, T., 476.Bach, D., 443.Racher, R. F., 53.Bachmetew, E., 203.Bachmutova, M. K., 462.Bacon, R. G., 257.Badger, A. E., 211.Badger, R. M., 61, 68, 71, 79, 82, 85,Bahr, K., 258.Biirwald, L., 342.Baumler, R., 366, 375.Baeyer, A. von, 21, 313.Bald, R. K., 159.Bahlfs, P., 204.Bailey, C. P., 366, 380, 355, 393.Bailey, C. R., 60, 62, 65, 132.Bailey, K., 241.86.48488 INDEX OF AUTHORS' NAMES.Bailey, W.F., 470.Bainbridge, K. T., 17, 142.Baird, D. K., 286.Baker, J. W., 108.Baker, W. N., 46, 48, 175.Balanescu, G., 460.Balavoine, P., 479.Baldwin, W. C. G., 123.Ball, W. C., 483.Baly, E. C. C., 116.Bambach, K., 455.Bandel, G., 46.Banerjee, K., 232, 234.Banerjee, P. C., 461.Banerjee, S., 223, 230.Banerji, S. K., 312.Bannister, F. A., 210, 216.Barac, G., 477.Baranowski, T., 411, 412.Bardhan, J. C., 312, 325.Barger, G., 341, 347, 403.Barinova, S. A., 442.Barker, E. F., 58, 60, 64, 65, 132.Barnes, C., 77, 80, 82, 83, 84, 85, 86,Barnes, L. L., 141.Barnes, R. B., 65.Barnes, W. H., 46, 47.Barnette, R. M., 440.Baroni, A., 172, 179, 204, 209, 221.Barr, G., 484.Barratt. S.. 177.87.Barreto; A:, 471.Barrett, J. W., 308, 309.311, 314. . _ -Barrow; F., 243.Barsha, J., 237.Bartels, W., 172.Bartelt, K., 327.Barth, T. F. W., 211, 212, 214.Bartholomk, E., 44, 45, 46, 84, 88.Bsrtunek, P. F., 65.Bary, P., 261.Bassett, H., 150.Bsstien, P., 176.Bates, J. R., 43, 47, 49, 99, 106.Battacharyya, R., 421.Bauer, O., 180.Baum, R., 167.Bsumann, W., 61.Baur, L., 290.Bawden, A. T., 482.Bawn, C. E. H., 41, 94, 95, 98, 102,Baylis, J. R., 480.Beams, J. W., 142.Bear, R. S., 241.Beck, G., 27.Becke, F., 336.Becker, B., 357, 404.Becker, G., 314, 315.Becker, H., 22.Becker, R., 97.Beckert, J., 458.264.Seebe, R. A., 113, 114.Beerbower, A., 155.Beevers, C. A., 197, 222.Bein, K., 121, 122.Beintema, J., 188, 218, 219, 226.Bell, D. J., 288.Bell, F., 248.Bell, J., 101.Bell, R.B., 94.Bell, R. P., 42, 43, 47, 49, 107.Belladen, L., 176.Bellucci, I., 454, 467.Belousov, A. M., 470.Belousov, M. A., 440.Belousova, A. G., 470.Belval, H., 288.Benedetti, E., 461.Benedict, W. S., 44, 119, 180.Beniya, K., 104.Bennett, G. M., 108, 127, 130, 131,Bennett, (Miss) H., 466.Bennett, R. D., 38.Bennewitz, K., 117.Bent, H. E., 176.Renton, A. F., 114.Benz, C. A., 242.Benz, F., 300, 301, 356, 357, 358, 404.Benz, P., 293, 300.Eerchet, G. J., 267.Berend, G., 116.Berg, H., 372.Berg, O., 143.Berg, R., 456.Bergel, F., 403.Berger, I., 99.Bergmann, E., 127, 128, 129, 131,133, 134, 137, 256.Bergmann, M., 418, 419.Bergwardt, E., 318.Berhenke, L. F., 134.Bernal, J.D., 46, 212, 216, 217, 222,223, 229, 230, 240.Bernhard, K., 415.Bernhauer, K., 445.Berry, A. J., 462.Bertein, F., 38.Bethe, H. A., 17, 18, 27, 34, 35, 37,181, 185.Beutler, R., 478.Bewilogua, L., 128.Bhabha, H. J., 35.Biefield, L. P., 228.Bielecki, J., 123.Bien, G. E., 478.Bijvoet, J. M., 209.Biltz, W., 170, 176.Birch, T. W., 402.Birkinshaw, J. H., 447.Biscoe, J., 241.Bittencourt, A. C., 471.Bitter, F., 189.Bjerge, T., 26, 27.132, 135INDEX OF AUTHORS' NAMES. 489Blagden, J. W., 319.Blair, C., 86, 89.Blair, R. D., 327.Blair, V., 218.Blanck, A., 470.Blanke, E., 478.Blaze, J. R., 422.Bleakney, W., 42, 50, 51, 11 7.Blewett, J. P., 194.Blue, R. W., 64, 81, 84, 85, 88.Blumendal, (Miss) H. B., 461.Blumenthal, D., 418.Boccucci, R., 321.Bodendorf, K., 245.Bodenstein, M., 90.Bockh, S., 382.Boeseken, J., 305, 476.Bohme, H., 245.Boehme, W., 115.Boning, K., 432.Boning-Seubert, E., 432Boersch, H., 132.Bohner, H., 178.Bolcato, V., 445.Bollen, W. B., 431.Bolliger, A., 465, 466, 478.Bondy, H.F., 16, 264.Bone, W. A., 101.Bonhoeffer, K. F., 43, 104, 105, 106.Bonner, L. G., 66.Bonner, T. W., 23.Bonner, W. D., 452.Bonnet, R., 445.Booth, H. S., 159.Borelius, G., 185.Borhn, B., 202.Borges de Almeida, A., 312.Born, M., 40, 96, 120, 121, 124, 126.Bornhak, R., 176.Rorodin, J., 363.Boruff, C. S., 484.Bose, D. M., 162.Bose, M. K., 464.Bosshard, M., 168.Bosshard, W., 278.Bost, R. W., 477.Bothe, W., 19, 21, 22.Botschwar, A.A., 175, 180.Bottomley, G. H., 49, 11 6.Bougault, J., 477.Bourgin, A., 93.Rowden, F. P., 49, 192.Bowen, E. G., 179.Bowen, E. J., 106, 108.Bowman, P. I., 44.Boys, 5. F., 123.Brack, A., 312.Braddick, H. J. J., 38.Bradfield, A. E., 317, 328.Bradley, A. J., 169, 174, 178,202,205.Bradley, R. S., 106.Braekken, H., 210, 235.Bragg, (Sir) W. H., 234.Bragg, W. L., 168, 185.Brard, D., 462.Brasseur, H., 221, 223, 224.Brattain, R. R., 65.Bratu, E., 46.Bratzler, K., 41, 42.Brauer, G., 99, 206.Braun, E., 123, 284.Bravo, G. A., 477.Bray, W. C., 104.IZredereck, H., 280.Bredt, J., 313.IZroit, G., 22.Breitner, S., 395.Brenchley, W. E., 438.IZrennecke, W., 114.13rentan0, J. C. M., 194.ISretschneider, O., 207.Brewer, A.I<., 16, 36.Brickenkamp, R. W., 474.Urickwedde, F. G., 44.Bridgman, P. W., 46, 156, 157.Briggs, T. R., 180.I3right, H. A., 453.Brigl, P., 272, 279.Brill, R., 206.Brillouin, 18 1.T3rindley, G. W., 194.I3rinkman, R., 105.13rinkmanq E . , 30 7.33riscoe, H. V. A., 42.Brockmann, H., 292, 300, 302.Brockway, L. O., 128, 132, 133, 209,Broda, E., 285.Brodski, A. I., 41.Broeker, W., 158.Bronsted, J. N., 107.Broich, F., 395.Broniewski, W., 173.Brown, A., 405.Brown, G. S., 38.Brown, R. S., 46, 47.Brown, W. G., 40, 80, 85.Brown, W. R., 433.Brubaker, W. M., 23.Bruchhausen, F. von, 353.Hrugger, M. G. van, 211.Brun, J., 45.Brunauer, S., 71, 79, 117.Brunck, O., 464.Bruni, G., 210, 265.Brunner, M., 254.Bruson, H.A., 254.Bryant, W. M. D., 85, 88.Buchman, E. R., 401, 402.Buckley, H. E., 189, 190.Budge, P. M., 178.Buerger, M. J., 189, 190, 194, 209,229.215.Bussem, W., 209, 217.Bullock, B., 467.Bumm, H., 201, 204.Q 490 INDEX OF AUTHORS’ NAMES.Bum, C. W., 158, 195, 211.Burckhardt, E., 349.Burge, W. E., 440.Burgers, J. M., 191, 193.Burgers, W. G., 191, 193.Burgevin, H., 440.Burkhardt, G. N., 300.Burkser, E. S., 473.Burriel, F., 467.Burton, E. F., 225.Burwell, J. T., 148, 225.Buswell, A. M., 480.Butenandt, A., 408,409,410,411.Butkevitsch, V. S., 442, 444, 445,Butler, C. L., 338, 422.Butler, J. A. V., 46.Butts, J. S., 416.Cabicar, F., 201.Cabrera, B., 46.Cady, G. H., 155.Caglioti, V., 202, 214.Cahn, R.S., 317.Caldwell, J. M., 455.Caldwell, J. R., 459, 466.Caley, E. R., 470.Camp, A. F., 440.Campbell, A. N., 177.Campbell, H. C., 102.Campbell, W. G., 291.Canneri, G., 175, 178.Carmichael, E. A., 423.Carmichael, H., 38.Carothers, W. H., 257, 265, 266,Carpenter, C., 222.Carpentier, G., 481.Carrothers, J. E., 102.Carter, H. G., 177.Carter, S. R., 288.Cartwright, C. H., 65.Caspari, W. A., 261.Cassie, A. B. D., 60, 62, 66, 132.Castiglioni, A., 481.Catalano, L. R., 471.Cattaneo, C., 291.Cnttelain, E., 477.Cattell, McK., 105.Cavanagh, B., 49, 116.Cavell, H. J., 161.cervinka, J., 470.Chadwick, J., 17, 24, 28, 34.Chalam, B. S., 421.Chalmers, T. A., 32.Chamot, E. M., 474.Champetier, G., 46, 237.Chandlee, G.C., 462.Chang, M. C., 475.Chang, T. L., 46.Chang, T V . Y., 443.Chapin, 12. M., 104.Chapman, A. T., 68, 74, 85, 87.267, 268.Chapman, A. W., 103.Chapman, D. L., 101.Chariton, J. B., 101.Charmandarian, M. O., 215.Chattopadhya, A. K., 462.Chen, K. H., 458.Chen, P., 475.Cheraskova, E., 460.Chiang, C. H., 464.Chiang, M. C., 475.Chibnall, A. C., 227.Chick, H., 404.Chien, S. L., 246.Chiewitz, O., 53.Childs, A. E., 483.ChirnoagB, E., 455.Chlorator-G.m.b.H., 485.Cholnoky, L. von, 296, 301, 304.Cholodny, N., 427.Chopre, R. N., 423.Chow, B. F., 105, 390.Christiansen, W. N., 42.Christie, E. W., 244.Chrobak, L., 220.Chrzaszcz, T., 444, 445.Chuang, C. K., 308.Churchill, A. V., 484.Cimeran, C., 464.Clark, A.L., 425.Clark, G. L., 211, 223, 241.Clark, H. C., 422.Clark, J., 321.Clark, L. M., 158.Clarke, H. T., 402, 418.Clarkson, C. E., 227.Clay, J., 37, 38.Clayton, J. O., 72, 85, 86, 87, 88.Cleave, A. B. van, 45.Clements, J. H., 63.Clemo, G. R., 48, 317.Cliff, I. S., 318.Clifford, I. L., 158.Clusius, K., 44, 45, 46, 84, 88, 101.Clutterbuck, P. W., 290, 447.Coase, S. A., 469.Cobler, H., 408.Cockcroft, J. D., 21.Cohen, 194.Cohen, E., 466.Colby, W. F., 66.Cole, S. S., 214.Colin, H., 288, 449.Colla, C., 221.Collie, C. H., 27.Collier, L. J., 202.Collins, A. M., 257.Collins, F. J. E., 227.Collins, G., 63.Compton, A. H., 37, 194.Compton, J., 282.Conant, J. B., 251, 361, 362, 363,365, 366, 367, 376, 379, 380, 384,385, 386, 387, 388, 390, 393, 395INDEX OF AUTHORS’ NAMES.491Conrady, A. E., 451.Constantinescu, E., 435.Cook, A. H., 308, 311, 312.Cook, E. W., 277.Cook, G. A., 49, 99.Cook, R. P., 127.Coolidge, A. S., 97.Coops, J., 314.Copping, A. M., 404.Coppock, J. B. M., 45.Corey, R. B., 220, 227, 240, 241.Cork, J. M., 139.Corner, G. W., 410.Cornish, R. E., 51.Cosslett, V. E., 211.Couders, A., 319.Cournot, J., 175.Cowley, E. G., 127.Cox, E. G., 161, 162, 164, 220, 221,Crabtree, R. W., 42.Craig, L. C., 346, 347, 348, 349.Crane, H. R., 21, 22, 23, 33.Cranston, J. A., 144.Crawford, F. H., 64, 65.Crawford, M. F., 16.Cremer, (Frl.) E., 98.Cretcher, L. H., 338, 422.Creuss-Callaghan, G., 465.Crews, S.K., 349.Crist, R. H., 70, 81, 86.Crocker, W., 429, 430.Cross, P. C., 61, 85, 133.Crossmann, F., 258.Crowfoot, (Miss) D., 164, 188, 194,Crowther, B. M., 21.Crozier, R. N., 259.Cruickshank, J. H., 46.Csalh, E., 207.Cullinane, N. M., 234.Curie, (Mme.) I., 25.Curran, W. J., 136.Curti, R., 208.Curtis, R. H., 452.Curtman, L. J., 470, 471.Cmmano, G., 321.Cutler, C. H., 416.Cuvelier, B. V. J., 470.Czaja, A. T., 428.Czyfewsky, B., 459.235.220, 221, 223, 230, 240, 250.Dadieu, A., 133.Daumichen, S., 84.Daggett, A. F., 40.D’Agostino, O., 20, 24, 37, 147.Dahl, O., 50.Dalal, P. H., 234.Dale, (Sir) H. H., 345, 350.Dalin, G. A., 70, 81, 86.Damansky, A. F. ,287.Damiani, I., 454.Damon, C. H., 463.Daniltchenko, P.T., 177.Danneel, R., 308, 309.Dannenbaum, H., 409.Darbyshire, J. A., 216.Daubner, W., 465.Dauth, B., 210.Davey, W. P., 175.David, K., 409,Davidson, J., 439.Davies, F:. H., 475.Davies, G. R., 165.Davis, C. O., 73, 77, 84, 85, 86.Davis, R. M., 135.Davis, T. L., 244.Dawson, D. H., 75, 84.Dearborn, R. B., 438.Debacher, M. O., 180.De Beer, E. J., 453.De Benedetti, S., 38.De Beus, J., 484.De Bruyne, J. M. A., 47, 135.Dockert, H., 213.Deckert, W., 459.Dee, P. I., 19.Deffet, L., 46.DeAandre, M., 213.De Forcrand, R., 159.Dbgard, C., 174, 203.Do Graeve, P., 478.Dehlinger, U., 139, 168, 173, 175, 183,Deitz, V., 85, 89.De Laszlo, H., 127, 137.Delsasso, L. A,, 21, 22, 23, 33.De Mallomann, R., 124.Demmler, G., 311.Dempster, A.J., 15, 16.Denigits, G., 458, 474, 477.Denk, G., 152.Dennison, D. M., 54, 58, 61, 64, 66,80, 81, 83, 84, 136.Denny, F. E., 430.Dent, C. E., 235, 361.De Rassenfosse, A., 221.Derge, G. J., 201.Derning, W. E., 223.Dersch, F., 258.Derx, H. G., 305, 320.Desai, R. D., 306.Desbordes, D., 443.Desnuelle, P., 478.Desveaux, R., 444.Deuel, H. J., jun., 416.Deutsch, A., 300.Dexter, S. T., 433, 434.Dey, A. N., 306.Dhar, J., 231, 234.Dhar, N. R., 420.Diamond, H., 44.Dick, J., 464.Dickinson, B. N., 220.Diekinson, R. G., 331.184, 185, 199, 201, 203492 INDEX OF AUTHORS’ NAMES.Dickinson, S., 239, 241.Dieke, G. H., 63, 64.Diels, O., 276, 316, 323.DiBnert, F., 483.Dietz, E. M., 362, 363, 366, 367, 376,379, 380, 385, 386, 388, 390, 393,395.Dikshit, 424.Dikusar, I.G., 437.Dillon, T., 449.Dinelli, D., 330.Dingemanse, E., 409.Dirschel, W., 338.Ditt, M., 464.Dittmar, C., 431.Diver, G. R., 345.Dix, E. H., jun., 178, 179.Dixit, K. R., 216.Djatlowa, E., 217.Dobbins, J. T., 463.Doehlemann, E., 46-Domvre, J., 317, 322.Dolecek, R. L., 32.Dolejgek, V., 143.Dols, M. J. L., 405.Dominikiewicz, M., 331.Donle, H. L., 130, 133.Donnay, J. D. H., 220.Dorfman, J., 169.Dorough, G. L., 267.Dostal, H., 101.Dostal, M., 254, 255.Drake, L. C., 114.Drake, N. L., 252.Drake, T. G. H., 405.Drevon, B., 477.Drew, H. D. K., 164, 460.Drift, A. J. W. van der, 459.Druce, J. G. F., 143, 468.Drumm, P. J., 390.Drummond, J. C., 407.Dubois, P., 211.Dubsky, J.V., 472, 473.Duckert, R., 472.Duden, P., 331.Dudley, H. W., 348.Diirr, M., 394.Dufrenoy, J., 441.Dulou, R., 318, 322.Dumont, E., 234.Duncan, A. B. F., 63, 86.Dunlop, D. M., 425.Dunn, R. W., 431.Dunning, J. R., 26, 27.Dupont, G., 318, 322.Dutcher, H. A., 484.Dwyer, F. P., 161, 215.Dgelepov, B. S., 32, 34.Dziengel, K., 235.Earp, D. P., 131.Eash, J. T., 174.Easson, L. El., 435.Eastwood, E., 63.Ebersberger, J., 373.Ebert, F., 207, 211.Eckart, C., 93, 94.Eckell, J., 119.Eckhardt, A., 20.Eckhsrdt, A. E., 422.Eder, J. M., 139.Edgar, C. E., 404.Edmonds, S. M., 471.Edson, N. L., 416.Edwards, A. J., 42.Edwards, C. A., 180.Edwards, M. W., 476.Eggers, I-I., 174, 175, 176, 203.Ehrenberg, W., 27, 38.Ehrenfest, P., 38, 66, 79.Ehret, W.F., 180.Ehrmann, W., 460, 462.Eichbaum, F., 485.Eichinger, E. C., 447.Eichler, H., 471, 473.Eidinoff, M. L., 84.Eilers, H., 285.Eisner, H., 105.Eitel, M., 471.Ekman, W., 169.Elam, (Miss) C. F., 191.Elander, E., 208.Elbe, G. von, 72, 84, 8G.Elchqrdus, R., 176.Elderfield, R. C., 273.Elert, W., 80.Elkin, E. M., 115.Elliott, K. A. C., 420.Elliott, N., 221.Ellis, C. D., 18, 20, 28, 32, 33.Elsasser, W., 27.Elsen, G., 16.Elvehjem, C. A., 357.Elvove, E., 484.EmelBus, H. J., 102.Emmett, P. H., 111, 113, 117.Ender, F., 406.Engel, G., 218.Engel, L., 127, 128, 129, 133, 134.Engels, L. L., 276.Enkvist, T., 323, 324.Erbacher, O., 142.Eremejev, M., 26.Eremina, E., 340.Eriksson, S., 201.Erlbach, H., 284.Erlenmeyer, H., 40, 42, 43, 44, 47.Erxleben, H., 429.Eubanan, F., 403.Eucken, A., 41, 83, 97.Euler, H.von, 292, 300, 357, 404.Evans, A. G., 96, 98.Evans, B. S., 462.Evans, D. P., 109.Evans, E. J., 179, 205INDEX OF AUTHORS' NAMES. 493Evans, K. M. C., 169, 202.Evans, M. G., 94, 96, 106.Evans, R. C., 198, 228.Evans, R. D., 17.Evans, W. C., 318, 325.Eveking, W., 237.Ewald, P. P., 191.Ewell, R. H., 217.Ewing, F. J., 213.Ewins, A. J., 347.Eyring, H., 41, 51, 71, 81, 86, 90,93, 94, 95, 107.Fabre, R., 304.Fagerberg, S., 203.Fahlenbrach, H., 19, 20, 46.Fair, G. M., 480.Fairbrother, F., 99.Fajans, E., 50, 115.Fajans, K., 468.Faktulin, K. N., 435.Falkenhausen, F.von, 478.Faltis, F., 353.Fan, H., 475.Fankuchen, I., 240.Farkaa, A., 39, 44, 45, 86, 93, 98.Farkas, L., 44, 45, 86, 98, 99, 103.Farmer, E. H., 257.Farmer, R. H., 130, 133, 134.Favejee, J. C. L., 238.Fawcett, E. W., 104.Federitenko, A., 225.Fedorov, B. P., 477.Feher, F., 225.Feigl, F., 468, 470, 473, 475, 477.Feldhaus, A., 353.Feldmann, R. W., 466.Ferguson, G. W., 241.Fermi, E., 20,24,25,26,27,28,58,147.Fernandes, L., 139.Fernholz, E., 409, 410.Ferns, J., 283.Ferrari, A., 208, 210, 221.Feuchter, H., 261.Ficklen, J. B., 467, 472.Field, (Miss) E., 341.Figala, N., 452.Filosofov, A. V., 453.Filser, L., 388.Finch, G. I., 210.Fink, G. A., 26, 27.Fink, W. L., 178.Finkelnburg, w., 225.Fischer, A.G., 322.Fischer. F. G.. 364.Fischer; H., 209.Fischer, Hans, 359,360,361366, 367, 368, 370, 371,374, 375, 376, 377, 378,381. 382. 383, 384, 385,388; 389; 391, 392, 393,396, 397, 398.., 362,372,379,386,394,365,373,380,387,395,Fischer, Hellmut, 457.Fischer, M., 369.Fischer, R., 478.Fischer, W. von, 455.Fischnich, O., 427.Flasch, H., 211.FlaschentrLiger, B., 415.Fleck, H. R., 455, 456.Fleischmann, R., 19, 27.Fletcher, C. J. M., 108.Fletcher, W., 423.Flick, K., 463.Forster, T., 86.Foex, E., 440.Fogg, H. C., 139.Folpmers, T., 480.Fonteyne, R., 242.Foote, F., 194, 200.Foote, H. W., 459.:Foote, M. E., 481.Forestier, H., 148.Forsee, W. T., 475.Forsh, L., 394.Fosbinder, R. J., 106.Fosse, It., 478.Foulk, C.W., 482.Fouretier, G., 210.Fowler, R. H:, 67, 70, 84, 88, 94, 188,Fowler. R. M.. 453.216, 222.Fowler; W. A:, 21, 22, 23, 33.Fox, J. J., 184.Franck, J., 103, 201.Frandsen, M., 51.Frangopol, C., 474.Fraser, F. R., 423.Frauendorfer, H., 353.Freche, H. R., 178.Frei, P., 357, 404.Frenzel, A., 207.Frere, F. J., 460.Freud, J., 409.Freudenberg, K., 61, 244, 279, 284,Freudenberg, W., 43, 122.Freundlich, H., 105.Frevel, L. K., 203.Frewing, J. J., 102.Freytag, H., 470.Fricke, R., 213.Friedlander, E., 17.Friedrich, H., 309, 310.Frisch, 0. R., 20, 27.Fritschi, J., 253.Fritzsche, H., 354, 358, 368.Frohlich, H. J., 206.Fromageot, C., 478.Frost, A. A., 51.Frost, A. V., 85, 87.Fuchs, B., 16.Fuchs, K., 184.Fuchs, O., 133.Fiirth, O., 476.288494 INDEX OFFuiioka.Y.. 65.Fuber, A. T., 425.Funk, H., 458, 464.Furter, M., 306.Fuss, V., 179.Fussler, I<. H., 36.Fylking, K. E., 208.AUTHORS' NAMES.Xeave, J. Z., 109.Gabriel, P., 468.Gaddie, R., 421.Ggrtner, H., 40, 42, 43, 44.Gallay, W., 253, 259.Gallego, M., 461.Gangl, J., 459.Ganguli, S. K., 423.Gans, D. M., 17, 24.Garner, W. E., 101, 102, 111, 112,Garrat, A. P., 102.Garthe, E., 237.Gaskin, J. G. N., 476.Gassner, G., 438.Gattiker, D. C., 164, 188, 221.Gauthier, J., 475.Gayer, F. H., 256.Gebert, E. B., 203.Gee, G., 101.Gehrckens, K. A., 130.Geib, K. H., 44.Geilmann, w., 460.Gemmill, C. L., 417.GennetB, P. R., 141, 142.Gentner, W., 28.George, W.H., 226.Georgian, N., 462.Gercke, A., 305, 309.Gerecs, A., 273.Gerhard, S. L., 61.Gerngross, O., 463.Gershinowitz, H., 94, 95.Gewing, M., 269.Ghering, L. G., 111.Ghose, T. P., 335.Ghosh, A. R., 404.Giacomello, G., 152.Giauque, W. F., 68, 69, 72, 75,77, 79, 80, 81, 84, 85, 86, 87, 88,89.Gibbs, E. M., 423.Gibbs, R. C., 141.Gibson, G. E., 79, 87.Gibson, R. O., 104.Gilbert, C. W., 19, 21, 38.Gilcreas, F. W., 482.Gille, R., 480.Gillespie, B., 43.Gingrich, N. S., 157, 226, 242.Giordani, M., 445, 466.Gladischew, I. T., 104.Glasstone, S., 127, 130, 131, 135.Glattfeld, J. W. E., 275.Glazunov, A., 167.114.Xeu, K., 156.:locker, R., 139.xuin, w., 359.hessin, J. D., 459.:o, Y., 149, 223, 226, 238.fodner, I.N., 85.foebel, E., 115.fopfert, H., 63.foetz, A., 190.foeze, G., 438.foldberg, M. W., 408, 410.Xoldfinger, P., 40, 43, 49.foldhaber, M., 17, 24, 28.Xoldschmidt, H., 89.foldschmidt, S., 306.soldstein, L., 218, 219, 220.foldsztaub, S., 213.sonell, H. W., 331.Xoodeve, C. F., 150.Xoodwin, T. H., 235.Joralczyk, R., 172.Zorchakov, G., 101.Gordon, A. R., 69, 77, 80, 81, 82, 83,84, 85, 86, 87, 89.Gorski, V. S., 185, 210.GOSS, F. R., 128.Gossner, B., 209, 213, 214, 217, 218,Goswami, M., 477.Goth, E., 311, 312.GotB, H., 468.Gotts, R. A., 162.Gottschaldt, W., 367, 386.Gottwick, R., 438.Goudsmit, S., 53.Gould, A. J., 42, 50, 51, 117.Gould, B. S., 447.Grace, N. S., 16.Grafkger, G., 306.Graf, L., 173.Graham, R.W., 179.Graue, G., 144, 145.Gray, F. W., 46.Gray, S. C., 101.Greene, C. H., 51.Gregory, C., 77.Gregory, C. H., 174.Gregory, G., 101.Greiff, L. J., 52, 70, 87.Grenko, J. D., 218,Grewe, R., 402, 403.Griengl, F., 167.Griffith, C. F., 281.Griffith, R. O., 104.Griffiths, J. H. E., 27.Grignard, V., 3 17.Grime, H., 209.Grimm, A., 139, 140.Grimm, H. G., 198.Grimmett, L. G., 31.Gros, R., 473.Gross, A., 305, 308.234INDEX OF AUTHORS’ NAMES. 495Gross, P., 41, 48.Gross, P. M., 135.Gross, S. T., 86.Grosse, A. von, 16, 25, 52, 144, 145,146, 147.Grosselfinger, H., 371.Groves, L. G., 47.Grubb, W. J., 319, 321.Grube, G., 166, 172, 173, 175,179, 180, 204.Gruner, H., 279.Griissner, A., 279.Grundmann, C., 296, 297, 302.Grundstrom, B., 65.Gruner, E., 209, 231.Gruner, J.W., 216.GuBguen, E., 449.Gunther, P., 217.Gurtler, F., 438.Guertler, W., 165, 175.Guha, A. C., 234. .Guha, B. C., 207, 234, 404.Guillet, L., 175.Guillien, M., 225.Gulland, J. M., 419.Gullans, O., 479.Gundermann, J., 222.Guntsch, A., 65.Gupta, J., 458, 459, 472.Gurin, S., 402, 418.Gutschmidt, H., 101.Gutzeit, G., 472.Gyorgy, P., 356, 404.Haagen-Smit, A. J., 429.Haas, M., 177.Haas, P., 449.Haberland, H., 361.Haddock, L. A,, 457.Hiigg, G., 188, 201, 208, 211.Hahnel, S., 456.Hardtl, H., 443.Hafstad, L. R., 21, 22, 50.Hahn, F. L., 467.Hahn, G., 336, 342.Hahn, O., 25, 142, 144.Ha,ines, E. C., 108.Hait, E., 289.Halban, H. von, 25, 105.Halban, H.H. von, jun., 177.Halbig, P., 360.Haldane, J. B. S . , 105.Halford, J. O., 43, 47, 83.Halford, L. J., 106.Hall, M., 470.Hall, W. H., 51.Hall, W. T., 465, 474.Halle, F., 238.Hallman, L., 416.Halpern, O., 41, 48.Hamasumi, M., 174.Hamer, P., 483.176,Hamill, W. H., 43, 105.Hammett, L. P., 109.Haminick, D. L., 103.Hampson, G. C., 137, 128, 130, 131,132, 133, 134, 135, 137.Hanford, W. E., 333, 334.Hanisch, G., 409.Hanson, D. , 180.Harada, M., 40, 42, 43.Harder, A., 203, 209, 210.Hardwick, P. J., 103.Hardy, J. D., 64.Hare, W. A., 132.Harington, C. R., 419.Harker, D., 209.Harkins, W. D., 17, 24.Harkness, R. W., 111, 113.Harmasch, E. P., 466.Harold, C. H. H., 480.Harral, J. C., 451.Harries, C.D., 329.Harries, K., 258.Harris, J. A., 139.Harris, L., 42, 45.Harris, L. J., 356, 402, 404.Harris, P. M., 228.Harrison, T. H., 202.Hartley, F., 461.Hartmann, H., 206.Hartridge, H., 105.Hartshorne, N. H., 475.IIarwood, H. F., 466.Harwood, J. F., 102.Hasenkamp, J., 381, 382, 383, 384,Haslam, J., 464.Hassel, O., 133.Hasselstrom, T., 327.Hassid, N. J., 113.Hatcher, W. H., 102.Haucke, W., 158.Haughton, J. L., 165, 173, 176.Haurowitz, F., 359, 361.Hauschild, A., 223.Hauser, E. A., 261.Haworth, W. N., 278, 279, 280, 286,Haxel, O., 20.Hecht, F., 460, 462.Heckmaier, J., 377, 389.Heczko, T., 461.Hedges, E. S., 179.Hedley, E. P., 454.Heesterman, J. E., 475.Heggie, R., 244.Heiduschka, A., 477.Weilbron, I.M., 297, 300, 302, 304,406, 407, 450.Heintze, K., 273.Heisenberg, W., 160.Heisig, G. B., 93, 470.Heisig, L. K., 470.Heitler, W., 79, 87, 90.397.287, 288, 290, 447496 INDEX OF AUTHORS’ NAMES.Helberger, H., 374, 376.Helfenstein, A., 292, 297, 302.Helferich, B., 280.Heller, K., 438.Hellmann, H., 92, 107.Hellstrom, H., 300.Helmholz, H. F., 425.Helmholz, L., 207.Hemmeler, A., 470.Henderson, M. C., 17, 22, 30.Henderson, W. J., 18, 20, 32, 33.Hendricks, S. B., 127, 131, 223, 229,Hendschel, A., 395, 396.Hengel, J. W. A. van, 207.Henri, V., 123.Henriquez, P. C., 307.Henry, A. J., 150.Henry, T. A., 337, 338, 423.Herfeld, H., 463.235.HHHHHH33HHHkrman, J..von, 239.krmano, A. J., 403.lerrick, H.T., 446.ierscovici, S., 466.:erszfinkiel, H., 27.Lertel, E., 228, 234,iertz, G., 50.[erz, W., 285.[erzberg, G., 63, 65.[erzfeld. E., 477.Herzfeld; K: F., 100, 27.Hess, K., 235, 237, 284.HBSS, R., 376.Hettner, G., 62.Heuer, W., 261.Heumann, K., 150.Heusler, O., 202.Hevesy, G. von, 26, 31, 32, 3G, 53,140, 141, 142.Hewitt, J., 238.Hewson, G. W., 482.Hey, M. H., 201, 210, 213, 216.Heyne, L., 257.Heyningen, W. E. van, 412.Heyrovsky, J., 143.Hibbert, H., 132, 237.Hicks, E. P., 422.Hicks, H. C., 68, 71, 75.Hilferding, K., 105.Hilgendorff, H. J., 63.Hill, A. V., 105.Hill, C. F., 215.Hill, D. W., 274.Hill, H., 16.Hill, J. W., 265, 267, 268.Hill, T. G., 449.Hille, J., 166, 175.Hillebrand, W. F., 452, 461, 468.Hilpert, S., 480.Hinman, J.J., 484.Hinshelwood, C. N., 97, 99, 100, 102,Hipple, J. A., 51, 52.107, 108.Hirano, S., 408.Hirst, E. L., 278, 280, 286, 287, 288.Hitchcock, A. E., 429, 430.Hjort, A. M., 453.KO, P. C., 32.Hoard, J. L., 218, 219, 220.Home, W. E., 180.Hoather, R. C., 150.Hobbie, R., 141.Hoch, H., 86.Hocheder, I?., 364, 365, 391.Hojendahl, K., 126, 127.Hoeke, F., 475.Ho11, K., 458.Holtje, R., 458.Honig, F., 277.Hoffer, M., 390.Hoffmann, A., 212.Hofmann, H. J., 398.Hofmann, U., 207, 216.Hofmann, W., 208.Holden, G. W., 345.Hollenweger, H., 215.Holluta, J., 464.Holmberg, B., 456.Holmes, E. G., 417.Holness, R. F. G., 455, 456.Holst, W., 64.Holzner, J., 217.Homer, C. E., 179.Hook, A.van, 102.Hopkins, B. S., 139.Hopkins, (Sir) F. G., 419, 420.Hoppe-Seyler, E., 368.Horiuti, J., 42, 43, 58, 96, 116, 119,Horn, K., 274.Horn, K. R. van, 178,201.Hornel, J. C., 105.Horrocks, H., 232.Horsley, L. H., 27.Hoshino, T., 340, 343, 344.Hough, W. A., 467.Houston, W. V., 56.Houtz, R. C., 253.Houwink, R., 269, 271.Hovey, A. G., 266.Hovorka, V., 460.Howard, J., 110, 112, 117.Howard, J. B., 58,65.Howe, E. E., 211.Hsu, T. T., 247.Hu, M., 475.Hubold, R., 156.Hudson, C. S., 272, 284.Hudson, H., 123.Hubner, H., 301.Huckel, W., 305, 307, 308, 309, 310,311, 312.Huni, E., 391.Hurbin, M., 306.Huffman, J. F., 52.Hug, E., 363, 364.120INDEX OF AUTHORS’ NAMES. 497Huggett, W. E., 319.Huggins, M. L., 197.Hughes, A.H., 106.Hughes, E. A., 234.Hughes, E. D., 53, 96, 109.Hughes, W., 440.Hulett, G. A., 452.Hull, D. E., 32.Hulme, H. R., 35.Hultgren, R., 157, 218, 226.Hulthhn, E., 64.Hume-Rothery, W., 166, 168, 169,Hund, F., 80, 84, 183.Hunter, E., 100.Hunter, E. C. E., 128, 131, 136.Hunter, R. F., 306.Hurst, C., 36.Husemann, E., 260, 261.Husson, A., 116.Hutchisson, E., 85.Huttenlocher, H. F., 214.Hyde, J. F., 361, 366, 376, 380, 384,Hyman, A. S., 418.185, 202.385.Iandelli, A., 205.Iball, J., 204, 230.Ievins, A., 465.Iijima, S., 112.Iitaka, I., 462.Illingworth, J. W., 220, 457.Ingold, C. K., 42, 43, 65, 109,Ingold, (Mrs.) E. H., 42.Insley, H., 217.Ionescu-Matiu, A., 466.Ipatiev, V. N., 255.Ipatiev, V.V., 469.Irvine, (Sir) J. C., 273.Isaacs, M. L., 482.Ishibashi, M., 458.Ishidate, M., 328.Ishimaru, S., 459, 460.Isler, M., 363.Ittmann, G. P., 83.Ivanova, V. S., 436.Iwas6, K., 179.127.Jackson, D. A., 16.Jackson, H., 300, 304.Jacobi, R., 288.Jacobs, L., 46.Jacobs, W. A., 346, 347, 348, 349.Jacquot, R., 445. ,Jaeckel, R., 33.Jaeger, F. M., 170, 203, 211.Jaeger, J. C., 35.Jaff6, F. W. M., 481.Jahn, C., 462.Jakob, L., 258.James, C., 139.James, F. W., 42.James, H. M., 97.James, R. W., 232.Jamieson, G. S., 446.Janes, R. B., 162.Jansen, B. C. P., 358, 401.Janson, S. E., 125.Jarmus, J. M., 455.Jarzynski, L., 338.Jaulmes, P., 42.Javillier, M., 465.Jean, M. L., 467.Jefferson, M. E., 127.Jeffery, F.H., 170.Jenckel, E., 178.Jenkins, F. A., 75.Jenkins, H. O., 232.Jennings, J. S., 469.Jensen, K. A., 131.Jesse, W. P., 195.Jette, E. R., 168, 194, 200, 203.Jcunehomme, W., 49.Jevons, W., 53, 72, 73, 74, 75.Jilek, A., 460.Jirkovsky, R., 473.Joff6, A., 190, 191.Johannsen, G., 16.Johnson, J. W. H., 481.Johnson, M., 61, 66.Johnson, T. H., 38.Johnston, H. L., 42, 51, 68, 72,Johnston, J. M., 422.Johnston, R. G., 320.Jolibois, P., 210.Joliot, F., 25.Jolley, L. J., 102.Jones, B., 180.Jones, H., 181, 183.Jones, I., 106.Jones, M. S., 425.Jones, P., 178.Jones, R. N., 304.Jones, W. D., 180.Jones, W. M., 179, 180.Jones, W. R. D., 173..Jordan, P., 120.Jorgensen, T., 64, 65.Joshi, R. M., 176.Joshimura, K., 432..Tost, W., 46, 101.Jowett, M., 415, 416.,Jukkola, E.E., 205.,Julian, P. L., 343, 344, 423.Juliusberger, F., 53, 96.Juneja, H. R., 335.Jungers, J. C., 44, 49, 50.JureEek, M., 478.Jurriaanse, T., 203.Just, F., 281.Just, J., 485.Justice, J. L., 85, 86.Juterbock, E. E., 102.74, 75, 77, 79, 84, 85, 86, 87, 88.73498 INDEX OF AUTHORS' NAMES.Kiiding, H., 144, 145.Kahane, E., 469, 472.Kahmen, W., 458.Kaltschevski, K. A., 435.Kaltschmitt, H., 356.Kamenz, E., 307.Kamerling, S. E., 362, 380, 385, 390.Kamieliski, B., 40, 42.Kao, C., 2175.Mao, C. H., 458, 475.Karaoglanov, Z., 467.Kardo-Syssojeva, E., 446.Karimullah, 403.Karrer, P., 292, 296, 297, 300, 301,302, 303, 304, 305, 354, 355, 356,357, 358, 404.Karssajevskaja, M.P., 463.Karstens, TV. K. H., 449.Kasansky, B. A., 316.Kassel, L. S., 66, 72, 77, 78, 81, 82,83, 84, 85, 86, 87, 151.Katarian, T. G., 435.Kato, S., 179.Katunski, V. M., 426.Katz, J. R., 238, 257, 270.Katzoff, S., 242.Kaufmann, W., 297Kaupp, E., 139.Kautz, S., 285.Kawakami, M., 167, 177.Kay, W. W., 453.Kazarnowsky, I., 2 17.Kearton, C. F., 103.Keeble, F,, 426.Keen, R. C., 219.Keesom, W. H., 225.Keggin, J. F., 220.Keimatsu, I., 353.Keller, F., 178, 179.Kempton, A. E., 17.Kendall, E. C., 419.Kenner, J., 337.Kenny, J. R., 422.Kenyon, H. F., 49.Kenyon, J., 244.Keresztesy, J. C., 401, 402, 403.Kerr, I?. F., 217.Kersten, H., 174.Kesztler, F., 336.Ketelaar, J. A. A., 188, 208, 209, 218.Keunecke, E., 119.Kharasch, M.S., 314, 349.Kienle, R. H., 266.Kiesselbach, T. A., 432.Kiessling, W., 375, 412.Kikuth, W., 421, 422.Kilpatrick, M., 104.Kilpi, S., 456.Kimbdl, G. E., 93, 184.King, A., 42.King, F. E., 343.King, G., 232.King, H., 339, 351, 406.King, H. S., 479.Kirby, J. E., 257, 267.Kirchner, F., 17, 18.Kirk, P. L., 467.Kishi, H., 458.Kiss, A. von, 104.Kistiakowsky, G. B., 63, 93, 102, 108.Kitagawa, M., 418.Kitajima, S., 467.Klages, F., 285.Klaiber, H., 180.Klar, R., 45, 51, 104, 118.Klason, P., 449.Klaveren, F. W. van, 402.Klebs, G., 367, 379, 380, 385, 386.Kleiderer, E. C., 349.Kleiner, H., 258.Klemperer, O., 35, 36.Kline, G. M., 252.Kline, L., 478.Klit, A., 47.Klotzer, F., 225.Klooster, H.S. van, 180.Klug, H. P., 218, 226, 227.Knaggs, (Miss) I., 234.Knasnik, W., 155.Kneser, H. O., 97.Knop, J., 461.Knowles, H. B., 460.Knunjanz, I. L., 421.Kobayashi, T., 343,344.Koblic, O., 147.Kocsis, E. A., 455.Kocsis, E. J., 468.Kogl, F., 425, 426, 429, 431.Kogler, F., 466.Kohler, J. Wt L., 225.Kohler, R., 176.Koehn, C. J., 357.Kolliker, R. A., 454.Koenig, K., 289.Koepfli, J. B., 428.Koppel, J., 194.Koets, P., 286.Kofler, A., 223.Kohler, E. P., 243.Kohlrausch, K. W. F., 57, 133.Kohlschutter, H. W., 45, 254.Kolkmeijsr, N. H., 207, 238.Kollo, C., 462.Kolpak, H., 239.Kolthoff, I. M., 469, 484.Komarovski, A. S., 472, 473.Komovsky, G., 204.Komp, W. H. W., 422.Komppa, G., 315, 323, 325.Kondo, H., 338, 352, 353, 354.Konopinski, E.J., 32.Konovalova, R., 340.Koontz, P. G., 65.Kopfermann, H., 16.Korczewski, M., 438.Kordes, E., 188, 211INDEX OF AUTHORS’ NAMES. 499Koren, C. J., 235.Korenman, I. M., 467, 468, 471, 474.Korman, S., 49.Kornfeld, G., 105.Koslovski, M. T., 474.Kosodaev, M. S., 35.Kostermans, D. G. F. R., 426.Kota, J., 460.Kotowski, A., 116, 139.Kovarski, L., 25.KBzu, T., 462.Kraemer, E. O., 285, 458.Kramer, J., 469.Kramers, H. A., 83.Kratky, O., 223.Kraus, O., 209, 213, 214, 218, 220.Kreuss, A., 51.Kremann, R., 171.Krilow-Drenowsky, A., 422.Krishna, S., 335.Krishnan, K. S., 207, 223, 230.Krishnaswami, K. R., 466.Kritschevski, I. L., 422.Krocsak, M., 99.Krohnke, F., 331.Kroeker, E.H., 446.Kronig, R. de L., 39, 53, 64.Kruh, O., 469.Krumholz, P., 469.Ksanda, C. J., 210.Kubelkov&, O., 461.Kudszus, H., 409.Kueck, P. D., 16.Kuhl, H., 459.Kuntzel, A., 239.Kussner, W., 347.Kiister, W., 359, 369.Kuffner, F., 333, 334, 336, 336, 352.Kuhlmann, A. G., 479.Kuhn, H., 16.Kuhn, R., 245, 292, 293, 296, 297,300, 302, 303, 317, 354, 355, 356,358, 359, 390, 402, 404.Kuhn, W., 121, 122, 123.Kukai, R., 104.Kulberg, L., 470, 472.Kumetat, K., 308.Kuper, J. B. H., 50.Kurag, M., 457, 463.Kurie, F. N. D., 24, 33, 34.Kurnakov, N. S., 173.Kurtschatov, B., 24, 27, 31.Kurtschatov, I., 24, 26, 27, 31, 32.Kurzniec, E., 172.Kussman, A., 166.Kutschment, M. L., 473.Laaksonen, A., 456.Laar, J., 209.Laby, T.H., 42.Lacleck, F., 351.Laffitte, P., 176.Laibach, F., 427.Lakatos, E., 376, 384, 389, 393.Lamb, F. W., 458.Lamb, S. A., 103.La Mer, V. K., 46, 48, 49, 95, 105,Lnmi, R., 448.Landau, L., 35, 189.Lange, E., 46.Langer, R. M., 93, 97.Langley, W. D., 478.Langseth, A., 47.Lansing, W. D., 285.Lapworth, A., 283.Laqueur, E., 409.Lasarev, V., 43.Lashkarev, W. F., 184.Lassb, R., 314.Latichev, G., 24.Lather, W. M., 25, 32, 50.La Tour, F. D., 227.Laurie, A. P., 470.Laurie, L. L., 109.Lauritsen, C. C., 21, 22, 23, 33.Laves, F., 199, 202, 204, 205, 206.Lavollay, J., 465.Lavrov, L., 101.Law, N. H., 104.Lawrence, E. O., 18, 22, 23, 30, 34.Lawson, C. G., 42.Lea, D. E., 27, 34.Le Blanc, M., 173, 211.Leckie, A.H., 65.Lederer, E., 300, 304.Lee, J., 303.Lee, J. van der, 414, 415.Leendertse, J. J., 256.Le Fanu, B., 426.Legard, A. R., 108.Legault, R. R., 349.Lehmann, 412.Lehmann, G., 339.Lehmann, H. L., 99, 123.Lehrman, L., 469.Lei, H. H., 475.Leithe, W., 351.Lemoigne, M., 444.Lemon, J. T., 154.Lengfeld, F., 152.Lennard-Jones, J. E., 45,97, 108, 112.Leopoldi, G., 457.Leprince-Ringuet, L., 38.Lesslie, (Miss) M. S., 249.Le Thierry d’Ennequin, L., 374.LettrB, H., 406.Leuck, G. L., 235.Leupold, E. O., 264.Levene, P. A., 274, 279, 282.Levi, G. R., 209, 219.Levi, H., 26, 31, 32, 103.Levin, A., 58, 62.Levine, V. E., 478.107.Letort, M., 100500 INDEX OF AUTHORS’ NAMES.Levinge, (Sir) R. V. H., 107.Lewis, B., 72, 84, 86:Lewis, C.M., 54.Lewis, G. J., 115.Lewis, G. N., 80, 51, 68, 73.Li, C. C., 247.Liang, P., 333.Libby, W. F., 25, 32.Liebhafsky, H. A., 104.Lifschitz, E., 35.Lincoln, A. T., 469.Lind, S. C., 50.Lindner, J., 452.Link, K. P., 290.Linnell, W. H., 461.Linstead, R. P., 235, 306, 308, 309,Linton, E. P., 136.Lipson, H., 197, 222.Livingood, J. J., 28.Livingston, M. S., 23, 30.Ljubitsch, N., 237.Lobeck, H., 44, 47.Lockemann, G., 459.Lockwood, L. B., 446.Lohberg, K., 199, 204, 211.Loewe, L., 301.LSwenberg, C., 415.Lowenberg, K., 322, 364.Loewi, 424.Lohmann, G., 442.Lohmann, K., 412, 413.Lohse, W., 465.Lomax, R., 240, 241.London, F., 90, 91.Long, E. A., 72, 79, 84, 86.Lonsdale, (Mrs.) K., 230.Loofs-Rassow, E., 179.Loomis, W.E., 440.Loring, A. D., 215.L’Orsa, F., 293.Losana, L., 179.Loskiewicz, L., 167.Lovern, J. A., 300.Lowe, A. R., 361.Lowry, T. M., 40, 121, 123, 124, 126,Lozier, W. W., 50.Lozinski, E., 345.Ludecke, H., 440.Ludloff, H., 79.Ludwiczakcjwna, R., 338.Luhr, O., 42, 45.Luis, E. M., 321.Lundell, G. E. F., 452, 461, 468.Luz, G., 443.L y d h , R., 462.Lyon, D. M., 425.Ma, C. M., 308.Maas, J., 174.Maass, O., 46, 46, 47, 136.Mabbott, G. W., 169, 202.311, 312, 314, 343, 360, 361.154.McAlevy, A., 318.McBride, R. S., 453.McBurney, C. H., 431.McCalla, A. G., 438.McCann, D. C., 218, 453.McCay, L. W., 459.McCollum, J. P., 427.McCrady, M. H., 481.McCubbin, R. J., 251.MacDonald, J. M., 317.MacDonald, R. D., 100, 102.Macdonald, R.T., 51.MacDougall, D. P., 80, 84, 85.MacGillavry, D., 88.Machatschki, F., 214, 216.Mack, E., 132.McKelvey, D., 423.McKenzie, A., 244, 245, 321.McKenzie, B. F., 419.McKeown, A., 104.Mackinney, G., 223.McKinney, P. V., 110.Maclachlan, W. W. G., 422.McLennan, J. C., 26, 31.MacMahon, E. J. R., 421.Macmillan, D., 275.McMillan, E., 22, 23, 30.McMorris, J. M., 86, 87.MacMurchy, R. C., 216.McQuillen, A., 48.Macwalter, R. J., 407.Magaria, R., 105.Magidson, 0. J., 422.Maitland, P., 243.Maiweg, L., 291.Majewski, F., 438.Majmin, R., 287.Major, R. T., 277.Majundar, A. K., 464.Makarova- Seml j anska ja, N. N., 289.Malarski, H., 386.Malkin, T., 227.Malkov, A., 476.Malmberg, M., 300, 357, 404.Mamoli, L., 410, 411.Manley, J.J., 451.Mann, F. G., 164, 188, 221.Mann, P. J. G., 420.Mann, T., 411, 413, 414.Manning, M. F., 66.Marchlewska, J., 285.Marchlewski, L., 368, 369, 370, 376,Marimpietri, L., 438.Mark, H., 101, 224, 235, 254, 255,Markov, V. K., 215.Marlies, C. A., 49.Maron, S. H., 104.Marsh, J. K., 26, 32.Marshall, C. E., 216, 217.Martin, A. E., 184.Martin, W. M., 435.386.331. INDEX OF AUTHORS’ NAMES. 501Martindale, 484.Martini, A., 474.Marwick, T. C., 241.Maslova, M. S., 456.Mason, H. L., 419.Massey, H. S. W., 97.Massini, P., 156.Masterman, S., 53, 96.Mathieu, M., 237.Mattikow, M., 479.Maugham, M., 291.Mauss, H., 421.Maxfield, L. S., 472.Maximov, A., 204.Maxted, E.B., 113, 115.Maxwell, L. R., 127, 131.May, 0. E., 446.Mayer, E. W., 325, 301.Mayer, J. E., 68, 71, 79, 82, 83, 85, 96.Mayer, M. G., 71, 79.Mayr, C., 463.Mead, T. H., 419.Meade, E. M., 311, 343.Meara, F. L., 166.Mecke, R., 54, 55, 56, 61, 132.Medick, H., 383.Medvedev, S., 258.Meerwein, H. F., 358.Megaw, (Miss) H. D., 46, 212, 213,Megson, N. J. L., 270.Mehlig, J. P., 465.Mehmel, M., 210, 214, 216.Meier, F. E., 448.Meisel, K., 208, 209.Meister, M., 244.Meitner, L., 25, 33, 144.Meldrum, N. U., 420.Mellor, D. P., 161, 215.MBlon, J., 220.Melsen, J. A. van, 330.Melville, H. W., 45, 101, 112.Melville, J., 420.MendelBef, D. I., 138.Meng, K. C., 475.Mentzel, R., 307.Menzel, H., 213.Menzschinskaja, E. V., 444.Merck, E., 461.Merka, A., 370, 375, 395.Merkurjew, N.E., 180.Merlo, L., 445.Meth, 361, 378.Meunier, P., 461.Meuwsen, A., 152.Meyer, C. F., 58, 62.Meyer, E., 179.Meyer, G. M., 279.Meyer, H., 133, 134.Meyer, Jules, 408.Meyer, Julius, 172.Meyer, K. H., 148, 149, 226, 237, 238,229.289.Meyer, R., 276.Meyer, R. J., 139.Meyerhof, O., 412.Meyling, A. H., 452.Michael, S., 446.Micheel, F., 274, 275.Michel-LBvy, A., 192.Middleton, A. M., 153.Middleton, A. W., 458.Mietszsch, F., 421.Migeotte, M., 65.Mika, J., 467.Mikaye, Y., 455.Mikulowski-Poinorski, J., 437.Milas, N. A., 318.Milkowski, K., 440.Miller, (Miss) C. C., 104.Miller, E. J., 458.Miller, L. P., 430.Millikan, G., 105.Mills, W. H., 162, 163, 243, 305.Milobedzki, T., 453.Minkow, I., 46.Misch, L., 203.Missovski, L., 26, 27, 31.Mitchell, A.C. G., 68, 71, 75.Mitchell, A. D., 456, 469, 475.Mitchell, D. P., 26, 27.Mittasch, A., 119.Miwa, M., 207.Miwa, T., 444.Meller, M., 452.Moelwyn-Hughes, E. A., 95, 104,105.Moggridge, R. C. G., 402.Mohrhenn, H. G. G., 109.Mohunta, L. M., 325.Moir, C., 349.Molchanov, S. P., 435.Moldenhauer, O., 366, 367, 375,Moller,E. I?., 390.Momose, T., 328.Montequi, R., 461.Montfort, C., 448.Montgomery, C. G., 38.Montgomery, C. W., 72, 85, 151.Montgomery, D. D., 38.Montgomery, E., 272.hfontignie, E., 449.Moon, C. H., 115.Moon, P. B., 26, 28.Mooney, R. C. L., 218, 219.Moore, H. F., 422.Morawietz, M., 158.Morey, G. W., 452.Morf, R., 292, 302.Morgan, G.T., 164.Morgan, J. E., 38.Morgan, S. O., 127.Morgan, V. G., 109.Morgenroth, R., 422.Morikawa, K., 44, 119.Morino, Y., 66.377502 INDEX OF AUTHORS’ NAMES.Morita, N., 42.Morral, F. R., 201, 203, 205.Morris, C. J. 0. R., 419.Morris, R. C., 335.Morris, S. G., 287.Mosley, V. L., 127.Mosley, V. M., 131.Mott, N. F., 32, 97, 184.Motz, H., 84.Mowry, H., 440.Moyer, H. V., 466.Moyer, W. W., 385, 386.Mrgudich, J. N., 241.Miiller, Adolf, 361.Muller, Alex, 227.Muller, Alexander, 2 8 1.Muller, F. H., 47.Muller, H., 407.Muller, 0. H., 49.Mukerjee, B., 477.Mukherjee, P. C., 207.Mukherjee, P. L., 218.Mulholland, H. P., 77, 82.Mulliken, R. S., 53, 62, 63, 75.Munch, J. C., 468.Mundt, H., 201.Muraour, H., 192.Murison, C.A., 210.Murphy, A. J., 176.Murphy, P. A., 440.Murray, 5. W., 86.Musgrave, F. F., 100.Muskat, I. E., 275, 282.Muus, (Miss) J., 104.Naab, H., 308, 309.Nachtigall, G., 483.Naeshagen, E., 133.Nag, N. C., 439.Nagelschmidt, G., 217.Nahmias, M. E., 34.Naidu, R., 34.Nakai, Z., 454.Narang, K. S., 333, 335.Narita, Z., 352.Natanson, L., 121.Nathan, W. S., 108, 109.Navratil, 424.Naylor, G. L., 449.Needham, D. M., 412.Neff, H., 234.Nelson, M. G., 426.Nemenu, L., 32.Nencki, M., 370.Neracher, O., 277.Nerdel, F., 309.Nespital, W., 136, 137, 210.Nouburger, M. C., 201.Neuert, H., 18, 21.Neuhaus, A., 223, 224.Neuman, E. W., 208.Neumann, B., 115.Newnann, F., 284.Neumann, F.W., 479.Neumann, W., 117.Neumann, Wilhelm, 361.Newell, I. L., 472.Newman, C. D., 421.Newman, F. H., 36.Newson, H. W., 17, 23, 24.Newton, R., 433, 435.Nichols, M. L., 467.Nichols, M. S., 481.Nicholson, F., 477.Nicloux, M., 478.Nielsen, H. H., 61, 62.Nielsen, H. R., 80, 83.Nielsen, W. M., 38.Nier, A. O., 36.Nieuwenburg, C. J. van, 461.Nieuwenkamp, W., 188, 209, 215.Nikawitz, E., 333.Nishigori, S., 174.Nishikawa, E., 448.Nitzberg, C., 344.Noack, K., 375, 396.Noddack, (Frau) I., 140, 141, 142,143, 148.Noddack, W., 141, 143.Noll, W., 465.Nordhagen, J., 45.Nordheim, L., 35.Nordheim, L. W., 166.Nordlund, M., 476.Norman, A. G., 238.Norris, J. F., 108.Norrish, R. W. G., 101, 102, 108.Nort hall-Laurie, D., 483.Nowak, K., 466.Nussler, L., 395, 396.Nuka, P., 463.Nyman, G.A., 325.Oberembt, H., 353.Oberlin, M., 338.Obogi, B., 285.Ochiai, E., 354.olander, A., 167, 177, 205.Oesper, R. E., 455.Oesterreich, K., 270.Offord, H. R., 470.Ogata, A., 408.Ogden, G., 41, 51, 52, 94, 119.Ogg, R. A., 95, 96, 102.Ogston, A. G., 402.Ohle, H., 279, 281, 282, 284.Okabe, K., 42.OkAE, A., 472.Olcott, H. S., 407.Oldham, J. W. H., 281.Oliphant, M. L. E., 17, 21.Oliver, E., 288.Oliver, W. F., 225.Olson, E., 469INDEX OF AUTHORS’ NAMES. 503Olsson, E., 64.O’Neill, H. T., 446.Oppenheimer, J. R., 23, 35.Orekhov, A., 340.Orelkin, B. P., 230.Orowan, E., 190, 193.Orr, W. J. C., 46.Orth, 0. S., 440.Osswa, A., 179, 202, 203.Oshima, K., 173.Ostern, P., 411, 412, 413, 414.Oswald, A., 304.Otani, B., 179.Ott, E., 203, 227.Otto, M.M., 132.Otuama, T., 449.Oschmsn, V. A., 461.Overstreet, R., 72, 77, 79, 80, 84,Owen, E., 201.Owen, E. A., 174, 204.Owen, J., 321, 322.Oxford, A. E., 447.85, 87.Paauw, F. van der, 449.Pace, J., 45.Pahl, M., 140.Pai, N. G., 132.Palibin, P., 28.Palit, C. C., 420.Palmam, E., 177.Palmen, J., 329.Pampsna, E. J., 423.Pan, Z. H., 464.Psnkow, G. W., 237, 289.Papapetrou, A., 190.Papish, J., 141, 142.Pamnjpe, G. R., 176.Paris, R., 176.Parker, A. E., 63.Parker, E. A., 241.Parks, W. G., 462.Parnas, J. K., 411, 413, 414.Parry, E. G., 300, 450.Partington, J. R., 127, 128, 131, 136,Paschke, B., 483.Passerini, L., 222.Pastorello, S., 172.Patat, F., 65, 84, 86, 100.Patterson, A.L., 195.Patterson, W. I., 247.Patton, A. R., 477.Pauling, L., 88, 132, 160, 197, 206,208, 209, 213, 218, 219, 229, 233.Paulus, R., 208.Paulus, W., 478.Paxton, H. C., 33, 34.Payne, R. J. M., 173, 176.Pearce, J. N., 134.Pearson, T. G., 100.Pease, R. N., 116, 118.159, 468.Pedder, 5. S., 177.Pegram, G. B., 26, 27.Peh, K., 438.Peierls, R., 183.P’ei- Hsiu Wei, 215.Peiskar, H., 249.Pell-Walpole, W. T., 180.Pelzer, H., 94, 103.Ponfold, A. R., 317, 328.Pong, C., 466.Ponner, A. J., 474.Ponney, W. G., 62, 128, 136, 249.Percival, (Mrs.) E. E., 276.Percival, E. C. V., 276, 288.Perkin, A. G., 250.Perkin, W. H., 313.Perkins, G. W., 476.Perlitz, H., 169, 203.Permar, H.H., 422.Perrin, F., 27.Perrin, M. W., 104.Pestemer, M., 171.Peter, F. M., 421.Peters, R. A., 402.Petersen, A. W., 203.Peterson, F. C., 291.Peterson, M. D., 25.Peterson, W. H., 446, 447.Petit, A., 175.Petrescov, K., 213, 220.Petri, H., 248, 249.Peyronel, G., 219.Pfaehler, K., 356.Pfannenstiel, A., 368.Phelps, R. T., 175.Phillips, H., 244.Phillips, M., 23.Phillips, T. G., 438.Phipers, R. F., 297, 302, 450.Phragmdn, G., 169.Piccard, J., 472.Pickup, L., 174, 201.Pieponbroek, K., 466.Pieper, B., 302.Pierard, J., 221.Pierce, W. C., 242.Pierson, G. G., 469.Pieters, H. A. J., 456.Pietsch, E., 116, 469.Pike, N. R., 472.Pikl, J., 343, 344, 423.Piland, J. R., 440.Pilzer, K. S., 220.Pines, A. I., 422.Pinkard, F.W., 161, 221.Piper, C. S., 465.Piper, S. H., 227.Pirsch, J., 315, 316.Pirschle, I<., 442.Pittman, (Miss) V. P., 244.Plank, E., 473.Plant, (Miss) M. M. T., 286.Plate, A. F., 316504 INDEX OF AUTHORS’ NAMES.Platz, H., 151.Platzer, N., 333, 334, 335.Plechner, W. W., 455.Plotz, E., 370, 375.Plyler, E. K., 58, 60, 62.Plotz, E., 388, 395.Podschuz, R., 331.Pogodin, S. A., 179.Pohland, E., 194.Pohlmann, R., 62.Polacci, G., 448.Polanyi, M., 42, 43, 49, 51, 90, 94,95, 96, 98, 102, 105, 106, 108,116, 117, 119, 120.Poljakova, A. M., 332.Poll&k, L., 468.Pollard, A., 227.Pollard, C. B., 475.Pollard, E. C., 22.Pollard, F. H., 102.Polonovski, M., 344, 477.Pols, P., jun., 476.Poltz, H., 127.Poluetkov, N.S., 472, 473.Ponndorf, W., 318.Ponomarjev, V. D., 469.Ponte, D., 445.Pontecorvo, B., 20, 24, 27, 147.Pontillon, C., 441.Pope, (Sir) W. J., 125.Popov, P. G., 469, 470.Poppe, G., 47.Popper, K., 16.Porter, C. R., 279.Porter, L. E., 469.Portevin, A., 176.Posnjak, E., 210, 212.Posternak, T., 277.Potschinok, C. N., 470.Powell, G., 247.Powell, H. M., 160, 185,219, 220, 221.Prakke, F., 239.Prandtl, W., 139, 140.Prasad, M., 234.Prebluda, H. J., 462.Preece, A., 180.Preiswerk, P., 25.Preobrashenski, N. A,, 331, 332.Preobrashenski, V. A., 331, 332.Preston, E., 453.Preston, R. D., 238.Prettre, M., 101.Price, W. C., 63, 64.Prichotko, A., 225.Prill, E. A., 447.Prim, J. A., 242.Pritchard, E.A. B., 423.Proferansowa, M. N., 476.Pruess, L. M., 447.Prutton, C. F., 104.Przylecki, S. J. von, 287.Pukirev, A. G., 456.Purdie, D., 164.Quastel, J. H., 415, 416.Quatram, F., 206.Qudrat-i-Khuda, M., 306.Quensel, W., 421.Quibell, T. H. H., 163.Rabinovitsch, E., 99.Raeder, F., 483.Rahmel, H. A., 38.Raibmann, B., 472.Raisin, C. G., 43, 65.Raistrick, I-I., 290. 447, 448.Ramage, G. R., 325, 326.Ramsperger, H. C., 100.Ranedo, J., 464.Rank, D. H., 65.Rasetti, F., 20, 24, 27, 147.Rasmussen, E., 16.Raudnitz, H., 292.Rawson, S. G., 465.Ray, B. P., 207.Ray, J. N., 325, 333, 335.Ray, K. W., 175, 179.Ray, P., 458, 462, 464, 472.Ray, P. R., 459, 464.Raymond, A. L., 279, 331.Raymond-Hamet, 341.Read, F.E., 461.Read, J., 31, 318, 319, 320, 321.Record, B., 288.Redlich, O., 46, 49, 66.Reed, H. S., 441.Rees, R. L., 482.Reiche, F., 68, 83.ReicheIt, H., 483.Reichert, B., 470.Reichstein, S., 217.Reichstein, T., 277, 279.Reid, J. D., 456.Reinemund, K., 404.Reinemund, R., 354, 358.Reinert, M., 423.Reinicke, R., 227.Reinkober, O., 54.Reis, J., 411, 412.Reischauer, €I., 1 1 1.Reith, J. F., 484.Reitmann, J., 332.Reitz, O., 43, 106.Renaud, P., 226.Renaudin, (Mme.), 467.Renaudin, J., 467.Rennerfelt, E., 441.Renniger, M., 191.Reppmann, W., 472.Reuter, F., 290, 447.Reverey, G., 310.Reyerson, L. H., 43, 102.Reynolds, F. M., 108.Reynolds, S. R. M., 410.Reynolds, (Miss), T. M., 333.Rheinboldt, H., 212INDEX OF AUTHOILS’ NAMES.505Rice, F. O., 40, 100.Rice, K. K., 40.Rice, 0. K., 94, 95, 100, 102.Richards, E. T., 177.Richardson, H. 0. W., 34.Richardson, J. R., 33, 34.Richman, E., 478.Richter, F., 314.Richtmyer, N. K., 284.Rideal, E. K., 45, 99, 101, 105, 106,108, 112, 118, 254.Rider, T. H., 455.Ridgion, J. M., 318.Ridler, K. E. W., 192.Riedberger, A., 227.Riedmair, J., 367, 377, 380, 381, 388,Riedl, H. J., 373.Riesch, L. C., 104.Riesenfeld, E. H., 42, 46.Riesenfeld, H. E., 42.Riiber, C. N., 272.Riley, H. L., 318.Rinck, E., 171, 172.Ripan-Tilici, R., 467.Rippel, A., 442.Ritchie, M., 100.Rittenberg, D., 48, 70, 73, 84, 85, 86,Ritzenthaler, B., 286.Roberts, I. O., 201.Roberts, J. K., 113.Robertson, G. J., 281.Robertson, J.M., 194, 197, 224, 230,231, 235, 361.Robertson, (Sir) R., 184.Robin, L., 422.Robinson, (Mrs.) G. M., 249.Robinson, H. M., 458.Robinson, P. L., 100, 127.Robinson, R., 249, 250, 330, 333, 339,Robinson, R. A., 104.Rodebush, W. H., 68, 85, 88, 94,Rodgers, J. W., 202.Roebling, W., 456.Romer, F., 458.Romer, G. H., 228.Rogers, H. C., 128.Roginsky, S., 93.Rogozinski, A., 194.Rohde, G., 438.Rohmann, A., 170.Rohrmann, W., 323.Rolfe, A. C., 107.Rolfe, H. G., 461.Rolla, L., 139.Roman, W., 469.Roots, Y. K., 75.Rose, M. E., 35.Rose, W., 382, 396.Roseman, R., 455.394.87.343, 422.99, 107.Rosenberg, A., 38.Rosenberg, H. R.. 410.Rosenberg, S., 102.Rosenbohm, E., 204.Rosenheim, A., 472.Rosenheim, M.I,., 425.Rosenhcim, O., 406.Rosenkewitch, L., 93.Rosenthal, J. E., 66.Rosenthal, W., 175.Ross, C. S., 217.Ross, W. F., 386.Rossi, A., 205.Rossi, B., 38.Rossi, C., 174.Rossi, G., 441.Rossini, F. D., 305.Rossmann, E., 476.Rotblat, J., 27, 31.Roth, E., 99.Roth, H., 293, 317.Roth, W. A., 314, 315.Rothemund, P., 381.Roughton, F. J. W., 105.Roussinov, I., 27.Routledge, D., 273.Rowland, E. S., 174.Royer, M., 477.Ruark, A., 36.Rudolph, L., 116.Rudy, H., 355, 356, 359, 404.Ruehle, A. E., 402.Ruff, O., 155, 207.I~uguzov, A. M., 435.Ruhemann, B., 194.Ruhemann, M., 225.Ruhkopf, H., 275.Rule, H. G., 248.Rumpett, H., 215.Rupe, H., 328.12ussel1, A. S., 177.Russell, P. F., 422.Russell, W. C., 405.Russell, W.W., 111.Russell-Wells, B., 449.Rutherford, (Lord) 17, 28, 138.Ruzicka, L., 305, 306, 312, 321,325, 326, 327, 328, 330, 408, 409,410.Rydon, H. N., 326.Rygh, O., 406.SB, A,, 474.Sachs, G., 168, 173.Sachs, M., 309.Sachse, 306.Sachsse, H., 42, 99, 100, 103.Sackur, O., 66.Sadler, A. M., 247.Sandig, K., 269.Saenger, H., 164, 221.Siingewald, R., 127506 INDEX OB AUTHORS’ NAMES.Sagortschev, B., 467.Sah, P. P. T., 475.Sahai, P. N., 227.Sakaguchi, K., 443.Sako, S., 248.Salcewicz, J., 437.Salle, A. J., 431.Salmoni, R., 213.Salomon, H., 354, 357, 358.Salow, H., 225.Samant, K. M., 406.Samec, M., 286.Samuel, L. W., 476.Samuel, R., 63.Sanchez, J. A., 477.Sanchis, J. M., 484.Sanders, J. P., 463.Sandford, E.J., 180.SAndor, S., 127, 128, 129.Santos, A. C., 353.Santos, J. A, 209, 220, 457.Sarver, L. A., 455.Saunders, W. H., 431.Saupe, E., 239.Sautner, K., 203.S a d , P., 20.Sawyer, W. W., 41.Scandellari, G., 441.Scanlan, J. T., 456.Schaad, J. A., 241.Schiifer, O., 258.Schaffhit, F., 432.Schales, O., 336, 342.Schanz, H., 479.Schapiro, E., 476.Schapovalenko, A. M., 473.Scharff, M., 331.Scharrer, K., 439.Schaufler, G., 173.Schay, G., 99.Scheepers, J., 40.Scheiber, T., 269.Schemjakin, F. M., 462.Schenck, F., 406.Schendel, G., 472.Schenk, P. W., 150, 151.Scherer, T., 389, 395.Scheuer, E., 177.Schierholtz, 0. J., 479.Schiflett, C. H., 50.Schischakov, N. A., 216.Schjanberg, E., 108.Schllipfer, M., 415.SchlBpfer, P., 305.Schlecht, H., 173.Schlientz, W., 296.Schlittler, E., 354.Schlubach, H.H., 288, 289.Schluter, R., 311.Schmid, E., 168, 177, 178, 191, 204.Schmid, L., 336.Schmid, W. E., 194.Schmidlen, J., 156.Schmjdt, Harry, 318, 319, 320.Schmidt, Herbert, 288.Schmidt, J., 201, 206.Schmidt, O., 97, 115.Schmidt, 0. T., 273.Schmidt, T., 16.Schmidt, W., 394.Schmidt, W. E., 199.Schmidtz, H., 483.Schmitt, F. O., 241.Schmitz, J., 313.Schmucker, T., 440.Schneider, A., 176, 204.Schneider, E., 396, 397.Schneider, H., 474.Schneiderman, H., 470.Schnell, J., 389.Schnetzler, K., 20.Schnitzspahn, L., 310.Schnorrenberg, E., 206.Schoeller, W. R., 462.Schon, K., 363.Schonberg, A., 473.Schonheimer, R., 48.Schopf, C., 339.Schopp, K., 354,355,356,357,358,404.Schofield, R.K., 476.Scholder, R., 152.Scholes, S. R., 214.Scholten, W., 210.Scholz, C., 340, 341.Schonhofer, F., 421, 422.Schoorl, N., 452.Schopfer, W. H., 430.Schorigin, P., 289.Schormdler, A., 372.Schoszberger, F., 203.Schottky, W., 171.Schreiner, H., 104, 171.Schroeder, W. C., 482.Schropp, W., 439.Schtschepkin, G., 26, 31.Schtscherbakov, A. P., 439.Schtschigol, M., 458, 468.Schtschukina, M. N., 331.Schuch, E., 173.Schuchowitzky, A. A., 97.Schuler, H., 16.Schiitz, W., 137.Schiitzler, K., 331.Schulek, E., 455.Schulemann, W., 421.Schulman, J. H., 106.Schultze, G., 80, 84.Schulz, G. V., 285.Schulz, H., 213.Schulz, L., 319, 320.Schulze, G. E. R., 214, 223, 226.Schumacher, G., 139.Schumacher, H.J., 62, 100.Schunck, E., 368.Schwab, G. M., 99, 114,115,116,117,119INDEX OF AUTHORS' NAMES. 507Schwartz, A., 309.Schwartz, C. M., 197, 222.Schwarz, R., 151, 153.Schwarz, V., 463.Schwenk, E., 318.Sconzo, A., 454.Scott, H., 165.Scott, R. B., 44.Scott, R. D., 480, 481.Searle, N. E., 247.Sederman, V. G., 203.Seemann, H. F., 167.Segr6, E., 20, 24, 27, 147.Seitz, F., 183.Selinov, I., 32.Selman, J., 257.Seltz, H., 171.Selwood, P. W., 46, 50, 51.Semenoff, N., 40, 101.Semerano, G., 108.Semmler, F. W., 325, 327, 329.Sen, B., 423.Sen-Gupta, S. C., 324.Sessler, P., 279.Sevag, M. G., 291.Seybold, A., 448.Shaha, A., 477.Sharratt, E., 221, 469.Shaw, G. T., 102.Sheehan, H.L., 453.Sherborne, J. E., 86.Sherman, A,, 92, 93.Sherman, J., 41, 219, 229.Shigematsu, S., 477.Shih, C., 475.Shimizu, Y., 166.Shinohara, K., 477.Shire, E. S., 21.Shirshov, A. A., 435.Short, W. F., 330.Shoyket, D., 175.Shuman, A. C., 142.Shutt, G. R., 244.Sibaiya, L., 15, 16.Sibelius, H., 464.Sickman, D. V., 102, 110, 114.Siday, R. E., 34.Sidgwick, N. V., 133, 160, 232, 234.Siebel, G., 168, 177.Siebel, H., 366, 367, 389, 391.Siedel, W., 374.Sierra, F., 467.Sieverts, A., 45.Simeons, A. T. W., 422.Simonart, P., 447.Simonsen, J. L., 316, 317, 318, 321,Singer, E., 407.Singleton, W., 180.Siradjian, J., 477.Sirk, H., 242.Sisson, W. A., 237, 239.Sitte, K., 36.322, 325, 326, 328.Sizoo, G.J., 33.Skrabal, A., 104.8krarnovsk9, S., 452, 458.Slanina, F., 445.Slater, J. C., 183.Sleator, W. W., 58, 62, 132.Slotta, K. H., 410, 478.Smallwood, H. M., 127.Smeets, C., 467.Smekal, A., 191.Smith, D. P., 201.Smith, E. R., 40, 51.Smith, F. A., 40, 51.Smith, F. L., 458.Smith, G., 447, 448.Smith, H. A., 85, 87, 89.Smith, 0. M., 484.Smith, P. T., 50.Smith, R. A., 49, 96.Smith, S., 345, 346, 350.Smith, T. O., 438.Smith, W. R., 102, 108.Srnyth, C. P.,. 47, .127, 128, 130, 131,Smvth, H. D.. 50.133, 135.Sndl, H. H., 28.Snethlage, H. C. S., 454, 470.Snijclers, C. J., jun., 459.Snow, C. P., 63.Snow, R., 426.Soddy, F., 144.Soderholm, 211.Sorensen, E. T., 27.Sbrensen, N. A,, 235, 272, 300.Solmsson, U., 292, 300, 305.Solomon, D., 180.Solomon, W., 337, 338, 423.Soltys, A., 346.Sommer, H., 477.Sommerfeld, A., 181.Sonn, A., 331.Soper, F.G., 95, 106, 107, 108.Sorby, H. C., 362.Sosnowski, L., 32.Sotgia-Rovelli, T., 455.Sotnikov, E. I., 441.Spacu, G., 457.Spacu, P., 461, 463.Spiith, E., 333, 334, 335, 336, 351,Spanagel, E. W., 267.Spangler, It. D., 242.Spaulcling, C. H., 479.Spedding, F. H., 50.Speiss, K. F., 206.Speitmann, M., 361, 378.Spencer, H. M., 85, 86.Spencker, K., 279.Spielberger, G., 394.Spielman, M. L., 99.Spiers, F. W., 194.Spinks, J. W. T., 65.Spiro, K., 345.352508 INDEX OF AUTHORS’ NAMES.gplfchal, J., 201.Sponer, (Frl.) H., 39, 53, 57.Spong, A. H., 152.Sprague, A. D., 62.Spring, F. S., 406, 407.Spriskov, A.A., 477.Ssinjakova, 8. I., 458.Stacey, M., 290, 447.Stackelberg, M. von, 206, 208.Staeger, R., 119.StBhl, S., 202.Stahl, W., 473.Stalony -Dobrzanski, J., 452.Stamm, H., 152, 468.Stanbury, F. A., 439.Stangler, G., 361, 371.Stansby, M. E., 484.Statham, F. S., 337.Stathis, E., 468.Staud, J. C. J., 108.Staudinger, H., 251, 253, 254, 259,260, 261, 263, 264, 284, 285, 321.Steacie, E. W. R., 44, 49, 100, 102,106, 112, 115.Stearn, A. E., 97.Stedman, E., 423, 424, 425.Stedman, (Mrs.) E., 423, 424.Steele, C. C., 385.Steenhauer, A. J., 478.Stefanovski, V. F., 462.Steffens, C. C., 86.Stciger, B., 472.Steil, O., 127.Stein, F., 422.Stein, G., 314, 316, 363.Steinberg, R. A., 442.Steinbruck, R., 459.Steiner, H., 48.Steiner, W., 99.Stenbeck, S., 177, 179.Stenberg, E.J., 422.Stenvinkel, G., 16.Stepanow, A. W., 191, 192.Stephani, G., 331.Stern, A., 361, 379, 387, 389, 391,392, 393, 396.Stern, O., 66.Sternberg, H., 336.Sterne, T. E., 80, 84, 85, 88.Stevens, M., 180.Stevens, H. P., 265.Stevens, W. H., 265.Stevenson, E. C., 38.Stewart, C. P., 421.Stewart, G. W., 242.Stewart, L., 116.Stewart, P. A., 245.Stichnoth, D., 248.Stillwell, C. W., 205.Stitt, F. B., 104.Stockdale, D., 169.Stoess, U., 441.Stokes, G. G., 362.Stoll, A., 345, 349, 350, 362, 363, 366,Stoll, M., 292, 306, 327.Stone, V., 115.Storfer, E., 473.Strachan, C., 45, 97.Strada, M., 214.Straka, L. E., 455.Strasburger, J., 173.Strassen, H.zur, 117.Strasser, O., 127.Strassmann, F., 25.Street, J. C., 38.Stricks, W., 49.Strock, L. W., 188, 207, 459.Strobele, R., 358, 404.Strong, F. M., 446.Strother, C. O., 110.Strunz, H., 216.Sturtevant, J. M., 107.Suckfull, F., 275.Sue, P., 460.Sus, O., 366, 376, 377, 380, 385.Sugden, S., 26, 32, 47, 160, 161, 163.Suginome, H., 296.Sun, C. E., 93.Sun, T. H., 475.Sunawala, S. D., 466.Suszko, J., 338.Sutherland, G. B. B. M., 64, 62, 66,77, 136, 249.Sutton, L. E., 127, 128, 130, 131, 132,133, 134, 135.Svensson, E., 16.Svirbely, W. J., 104.Swann, W. F. G., 36.Swaryczewski, A., 228.Swientoslawski, W., 479.Swisher, R. D., 43, 106.Sykes, C., 165, 187.Syrkin, J. K., 104, 106, 107.Syromiatnikor, R. R., 180.Szabo, A.S., 51.Szilard, L., 27, 32.Szniolis, A., 485.379, 381, 391, 392, 395, 396.SzczypiIlski, w., 453.Tabuteau, J., 318.Tacke, (Frl.) I., 143.Tadokoro, T., 432.Takahashi, T., 292.Takane, K., 213.Takvorian, S., 140.Talibi, G. A., 440.Tamaru, K., 202.T a m , G., 46.Tammann, G., 46, 115, 170.Tanaka, M., 28.Tananaev, N. A., 465, 466, 468, 469,Tanner, H. G., 101.Taran, E. N., 476.470, 473INDEX OF AUTHORS’ NAMES. 509Tareer, E., 421.Tarejew, E., 421.Tam, H. L. A., 420.Tarvin, D., 480.Tate, P., 421, 422.TaurinB, A., 463.Taylor, G. I., 192.Taylor, H. A., 102.Taylor, H. J., 24.Taylor, H. S., 42, 44, 45, 46, 47, 49,Taylor, M. W., 405.Taylor, N. W., 176, 214.Taylor, T. C., 287.Taylor, W., 109.Taylor, W.G. A., 202.Taylor, W. H., 216, 234.Tazawa, Y., 417.Tchuiko, N. M., 176.Teal, G. K., 39, 41, 47, 64, 70.Teller, E., 64, 60, 61, 63, 66, 70, 71,Temkin, M., 46.Tempus, M., 277.Terlikowski, F., 440.Torpstra, P., 226.Tetrode, H., 66.Thayer, L. A., 483.Theilacker, W., 136, 224, 228.Theorell, H., 404.Thiele, H., 207.Thimann, K. V., 428.Thomann, G., 328.Thomas, E. B., 209.Thomas, E. N. M., 238.Thomas, P. E., 478.Thompson, H. W., 102, 103, 108.Thompson, J. W., 65.Thompson, M. R., 349.Thomson, D. W., 46.Thomson, (Sir) J. J., 126.Thornton, R. L., 23.Thornton, W. M., jun., 455.Thorogood, A. L., 484.Thouet, H., 313.Thron, H., 338.Thunberg, T., 441.Tielsch, H., 38.Tilley, C. E., 213.Tillman, J. R., 26, 28.Tirnmermans, J., 46, 47.Timmis, G.M., 315, 346, 350.Timofeeva, A. G., 445.Timofeeva, M. T., 436.Tin, S., 296.Tischtschenko, D., 452.Tischtschenko, F. E., 175.Tisdall, F. F., 405.Tishler, M., 243.Tisza, L., 58, 60.Titani, T., 40, 42, 43.Tod, H., 425.Todd, A. R., 403.50, 51, 110, 111, 114, 117, 119.81, 87.Todd, H. R., 480.Toeppfsr, H., 279.Tolansky, S., 16.Tolman, R. C., 68, 71, 102, 107.Tomi, W., 328.Tomita, T., 418.Tomiyama, T., 477.Tomlinson, M., 402.Tomonari, T., 237.Tonn, W., 180.Topley, B., 53, 70, 71, 81, 86, 87, 96.T6th, G., 275.Tougarinoff, B., 464.Trautz, M., 89.Travers, M. W., 100, 108, 117.Treadwell, F. P., 465.Treibs, A., 330, 359, 360, 361, 367,368, 371, 395, 398.Treibs, W., 329.Trelease, H.M., 437.Trelease, S. F., 437.Tress, H. J., 460.Trevan, T. W., 423.Trillat, J. J., 148, 237.Triolo, A., 176.Trischin, P. I., 468.Trkal, V., 66, 79.Trofimova, E. I., 444.Trogus, C., 235, 237.Tronev, V. G., 469.Tronstad, L., 45.Trtilek, J., 472.Tschabau, A. S., 184.Tschapigin, V. F., 462.Tschernichov, J. A., 463.Tschernig, K., 408.Tschesche, R., 401, 403.Tschitschibabin, A. E., 331.Tschopp, E., 408.Tschudnovski, M., 127, 129, 131, 133.Tschugaeff, L. A., 161.Tseng, C. L., 475.Tsu Tung, K., 35.Tsuda, K., 354.Tswett, M., 362, 363.Tiibin, R., 217.Tucholski, T., 118.Tuleen, L. F., 453.Tunell, G., 210.Turkevich, J., 111.Turner, E. E., 249.Turner, H. McN., 248.Turner, W. E. S., 453.Turova-Pollak, M.B., 307.Tiwe, M. A., 21, 22, 50.Tuzson, P., 296, 297.Tysdal, H. M., 435.Ubbelohde, A. R., 108.Udolskaja, N. L., 435.Ueno, K., 296.Ueno, S., 167, 175510 INDEX OF AUTHORS’ NAMES.Uhlenbeck, G. E., 32, 35, 136.Uhrova, A., 426.Ulich, H., 136, 137, 249.Ulmann, M., 237.Upthegrove, C., 174.Urazov, G. G., 179.Urbach, C., 485.Urban, W., 473.Urey,H. C., 39, 40, 41, 42, 46,47,51,52, 64, 68, 70,71, 73, 84, 85, 86, 87.Uslar, H. von, 457.Utzinger, M., 364, 367, 374, 385.Uyeo, S., 338, 352.Uzel, R., 455, 458.Uzumasa, Y., 455.Van Bever, A. K., 209.Van-Huan, T., 422.Van Natta, F. J., 267.Vance, J. E., 459.Vargha, L. von, 279, 280, 282, 284.Vartiainen, A., 350.Vasee, E. V., 108.VBsquez, S., 477.Vasserman, E. S., 456.Vassiliev, G., 442.Vassiliev, I.M., 436.Vassiliev, K. V., 207.Vassilieva, N. G., 436.Vassiliou, A., 470.Vaughan, W. E., 85, 87, 89.Vavon, G., 116, 319.Vavrinecz, G., 235.Veal, F. J., 111, 112, 114.Veen, A. G. van, 418.Vegard, L., 225.Veissbruth, L., 460.Velasco, J. R., 105.Velitschko, I. P., 175.Venkatesachar, B., 15, 16.Verdeil, 373.Vergnoux, M. S., 481.Verhoek, F. H., 100, 102.Verhulst, J., 218.Verkade, P. E., 314, 414, 415.Verley, A., 317.Vernon, W. H. J., 452.Verb, J., 174.Verwey, E. J. W., 188, 211.Vesselovsky, V. V., 102, 207.Veszelka, J., 178.Vetter, H., 402.Vibe, A., 31.Victor, E., 99.Villard, P., 159.Villars, D. S., 71, 79, 80, 84, 85, 92.Vincent, M., 421, 422.Viney, I. E., 81.Visintin, B., 466.Vladimirov, A. V., 437.Vleck, J.H. van, 92.Vogt, E., 166, 167.Togt, H., 172.Told, R. D., 84, 86.Toorhis, S. N., van, 50.Toorst, F. T. van, 452.Toskuyl, R. J., 51.Toss, G., 424.Josskuhler. H., 172, 173, 176.Jucetich, D. C:, 465.Wachholder, K., 421.Wade, T., 65.Nadano, M., 237.gaddington, G., 102.Uagenaar, M., 478.GVagner, C., 171.Wamer. E.. 473.m a s e r ; G.; 119.magner-Jauregg, T., 245, 257, 402.Wagstaff, (Miss) A. I., 235.Wahl, M. H., 40, 42, 46, 51, 62.Waine, A. C., 286.Wainer, E., 141.Walach, B., 360.Waldbauer, L., 213, 453.Walke, H. J., 36.Walker, J., 318, 321, 330.Walker, J. T., 243.Walker, M. B., 423.Walker, M. K., 68, 72, 74, 84, 86.Walker, O., 292.Wallis, E. S., 409.Walls, W.S., 130, 131, 133, 135.Walter, G., 269, 270.Walton, E. T. S., 21.Wandenbulcke, F., 483.Wa,rburg, O., 395.Ward, A. F. H., 112, 113.Ward, A. G., 217.Ward, A. M., 109, 153, 455, 456, 459.Ward, G. E., 446.Ward, H. I<., 242.Ward, J. C., 468.Wardlaw, W., 161, 164, 221, 469.Warhurst, E., 99.Warner, J. C., 104.Warner, J. D., 440.Warren, A. E., 225.Warren, B. E., 148, 157, 207, 215,Warren, W. J., 241.Warrick, E. L., 104.Washburn, E. W., 40, 51.Wassermann, A., 314.Wassermann, G., 177, 178, 204.Waterhouse, E. F., 462.Waterman, H. I., 256.Watermann, R. E., 401, 403.Watson, F. J., 454.Watson, H. B., 109.Watson, J. A., 473.Watson, W. W., 63, 65.Weber, C, O., 261.226, 242INDEX OF AUTHORS' NAMES. 51 1Weber, K., 105, 306.Weber-Molster, C.C., 273.Webster,K. C., 161,162,164,220,221.Webster, L. A., 52.Weeks, M. E., 455.Weerden, W. J. van, 226.Weerts, J., 173.Wehner, G., 173, 211.Wehrli, H., 292, 297, 302.Wehrli, M., 16.Wehrli, S., 254.Weibel, R., 472.Weibke, F., 172, 174, 175, 176, 203,Weichmann, H. K., 371.Weidinger, A., 238.Weinbaum, S., 206, 209.Weiss, J., 53, 96, 105.Weissberger, A., 127.Welch, K. N., 331.Wells, A. F., 160, 219, 221.Wells, W. F., 480.Wenck, P. R., 447.Wendenburg, K., 191.Wenderlein, H., 393.Wenger, P., 464.Wenker, H., 456.Went, F. W., 428.Wentz, A., 258.Wentzel, G., 19.Wenzke, H. H., 137.Werner, C. O., 223.Werner, H., 342.Werner, T. H., 376,390,303,395.Wertenstein, L., 27.Weryha, A., 176.Wesly, W., 453.Wesolowski, K., 173.West, C.D., 188, 203, 217, 221, 222,Westcott, C. H., 26, 27.Westgren, A., 166, 169, 179, 180, 201,202, 203, 205, 208WBtroff, G., 460.Wettstein, A., 292, 408, 409.Weygand, F., 354, 355, 356, 358, 404.Wheeler, A., 118.Wheland, G. W., 233, 251.Whitaker, H., 42.Whitby, G. S., 253, 259.White, A. C., 423.Whitmore, F. C., 251, 256.Whitmore, W. F., 474.Whytlaw-Gray, R., 42.Wickwire, G. C., 440.Widmann, A., 45.Wiebe, R., 7.5, 85, 86.Wiedemann, E., 363, 366, 367, 368,371,379,381,391,394,395,396.Wierl, R., 128, 136.Wiest, P., 168.Wightman, W. A., 307.Wigner, E., 93, 94, 183.209.226.Wilcox, D. E., 405.Cilcoxon, F., 430.Wildner, E. L., 114.WiIhelm, A. F., 432.VC'ilkie, D. P. D., 423.Wilkins, E. S., jun., 458.Willard, H. H., 454, 458.Willavoys, H. J., 101.A'illey, L. A., 178.Williams, D. P., 421.Williams, E. F., 227.Williams, E. J., 35, 168, 185.Williams, R. F., 436.Williams, R. J., 431.Williams, R. R., 401, 402, 403.Williamson, A. T., 100, 107.Willis, L. G., 440.Willott, W. H., 179, 205.Willson, K. S., 159.Willstatter, R., 362, 363, 364, 365,366, 367, 368, 369, 370, 374, 385,386, 391, 394, 395.Wilman, €I., 211.Wilson, C. L., 43, 48, 65.Wilson, D. A., 227.Wilson, E. B., 80.Wilson, J. J., 440.Wilson, J. L., 93.Wilson, N. A. B., 320.Wimmer, G., 440.Winchell, A. N., 218.Wind, A. H., 325, 326.Windaus, A., 310, 401, 403, 406, 407.Winkler, C. A., 100, 108.Winkler, S., 477.Winter, 0. B., 458.Winterstein, A., 297, 300, 303, 363.Wirtz, K., 44.Wise, L. E., 291.Witmer, E. E., 77, 85.Wittig, G., 248, 249.Wohler, L., 463.Wojciechowski, M., 51.Wolf, M., 227.Wolf, W., 176.Wolfenden, J. H., 41, 42, 47, 100.Wolff, H. A., 128, 133.Wolfke, M., 34.Wolfrom, M. L., 123.Wollthan, H., 258.Woltersdorf, G., 158.Wompe, A. F., 331.Wood, L. J., 209.Wood, R. G., 234.Wood, R. W., 65.Woods, H. J., 238.Woodward, G. E., 420.Woodward, R. H., 38.Woolgar, (Mrs.) M. D., 287.Wooster, (Mrs.) N., 164, 188, 221.Worschitz, F., 239.Wsigge, W., 460.WOO, S.-C., 79, 82, 85, 86512 INDEX OF AUTHORS’ NAMES.Wright, H. R., 450.Wurstlin, F., 234.Wulff, J., 167.Wyatt, G. H., 164, 460.Wyckoff, R. W. G., 198, 218, 220,Wylzalkowska, W., 104.Wynne-Jones, W. F. K., 46, 49, 95,227, 240, 241.107.Yamagata, S., 443.Yamamoto, R., 296.Yamanobe, T., 462.Yantschulewitsch, J., 309.Yntema, L. F., 139.Yoshii, S., 444.Yost, D. M., 86, 87, 89.Yost, D. W., 155.Yost, F. L., 22.Young, H. A., 50.Young, H. H., 108.Young, J. W., 452.Young, (Miss) P., 454.Young, R. S., 439.Yuan, H. C., 246, 247.Yuster, S., 102.Zacharewicz, W., 318.Zachariasen, W. H., 208, 213, 218,219, 229, 242.Zakomorny, M., 444, 445.Zanstra, J. E., 203.Zapf, G., 45.Zappert, R., 477.Zechmeister, L., 275, 291, 296, 297,301, 304.Zehnowitzer, E. W., 191.Zeile, K., 371.Zeise, H., 71, 72, 86, 87, 89.Zeiser, H., 273.Zeitschel, O., 318, 320.Zelinski, N. D., 307.Zemplbn, G., 273.Zener, C., 108.Zeppelin, H. V., 204.Zerrweck, W., 272.Zertschaninova, T. K., 461.Zervas, L., 279, 419.Ziegler, G. E., 222.Ziegler, K., 258, 306.Zijp, C. van, 474.Zimmerman, F. W., 430.Zimmerman, P. W., 429, 430.Zimmermann, W., 325, 326.Zinalt, E., 158.Zintl, E., 158, 176, 203, 204, 206, 209,Zormornev, G. M., 179.Zscheile, F. P., 363.Zubrys, A., 300.Zwierzchowski, R., 338.Zyw, M., 27.210

ISSN:0365-6217    

DOI:10.1039/AR9353200487

出版商:RSC    

年代:1935

数据来源: RSC

摘要:

INDEX OF SUBJECTSABRINE, 340.Abrus precatol.ius, alkaloid from, 340.Acetaldehyde, condensation of, withsugars, 280.decomposition of, 100.Acetic acid, basic beryllium salt,structure of, 229.ethyl ester, acid hydrolysis of, 104.methyl ester, hydrolysis of, 105.detection of, 477.Acet-8-naphthalide, thiol-. SeeAcetone, decomposition of, 100.Acetophenones, nuclear substituted,hydrogen-ion catalysed proto-tropy of, 108.Acetylene, polymerisation and hydro-genation of, 102.molecules, internuclear distancesin, 65.Acetylglycollic acid, basic hydrolysisof, 104.Acids, fatty, oxidation of, in viuo,414.organic, production of, by moulds,444.Acraldehyde, electronic spectrum of,63.Actinia equiw. See Sea anemone.Actinioerythrin, 304.Adamantine compounds, 205.Adenosine &phosphate, formation of,in muscle, 41 1.Adipic anhydride, polymeride of, 267.Adsorbents, solid, surface structureof, 115.Adsorption, 109.activated, 110.Xtioporphyrin-11, 3 7 3.Alcohols, reagents for, 475.Aldehydes, reagents for, 475.Algae, 448.effect of temperature on respirationand Etssimilation of, 449.brown, fucoxanthin in, 302.calcareous, metabolism of, 449.Thionalide.decomposition of, 102.Aliphatic compounds, structure of,Alkaloids, 331.,41kyl sulphides, valency angle of227.sulphur in, 131.Alloys, structure of, 181, 198.order-disorder transformations of,non-ferrous, 165.Aluminium, determination of, 462.determination and separation of,Aluminium alloys, 177.with barium, 205.with iron, 203.with magnesium, 167, 204.with silver, 167, 175.with zinc, 204.Aluminium bromide, dipole momentand structure of, 136.carbide, structure of, 206.chloride, effect of, on Walden in-version in sugars, 284.Alums, structure of, 222.Amalgams.See Mercury alloys.Amines, colour reactions of, withAmino-acids, 417.Ammonia, dipole moment and struc-molecules, in ternuclear distancesliquid, use of, in sugar chemistry,production of, in muscle, 414.184.460.chloranil, 477.mgents for, 475.ture of, 136.in, 65.275.a-Amylodextrin, 286./3-Amylose, distinction of, from a-amylose, 287.Analysis, apparatus for, 479.reagents for, 456.inorganic, 451.organic, 475.qualitative, 468.quantitative, 451.colorimetric, 477.microchemical, 477.quantitative, 476.hdrostanediol, 408.Qndrostanedione, 408.4ndrostenedione, 409.'L- and iso-Androsterones, 408.dnemonia sulcata, lipochrome from,4neurin.See Vitamin-B,.4ngler fish, astacene in, 300.volumetric, standards for, 452.304.REP.-VOL. XXXII. 513 1514 INDEX OX SUBJECTS.Anhalinine, 336.Anhalonine, structure of, 336.&-Anhalonine, resolution of, 336.Anhalonium Lewinii, alkaloids from,@hydro-osazones, 276.Anhydrone.” See Magnesium per-Anhydro-psicose, conversion of fruc-Anhydro-sugars, 280.Animals, biochemistry of, 401.Anisole, oxygen valency angle in, 135.Antheraxant hin , 304.Antimony, detection of, 472, 474.Antimony alloys with aluminium,336.chlorate.tose into, 283.178.with lead, 171.with magnesium, 176.with thallium, 205.with tin, 179.Antipyrine, detection of, 478.Apocinchene, 337.n- and Go-Apoquinidines, 338.Apoquinine, 338.Arabinose, mutarotation of, 272.p-Z-Arpbinose, rotation of, 272.d-Arginine anhydride tetrahydro -chloride, 417.Argon, thermal analysis of mixturesof boron trifluoride and, 159.Aromatic compounds, structure of,229.Arsenic, detection of, in presence ofantimony, 469.Arsenic alloys with tin, 179, 205.Arsenides, structure of, 208.Ascorbic acid, synthesis and deter-Aspergillus glaucus, pigments from,Aspergillus melleus, mellein from, 448.Aspergillw niger, mineral nutritionAspergillus terreus, terrein from, 448.Asphalt, porphyrins in, 398.Astrtcene, 300.Astucua gcvmmarus. See Lobster.Atebrin, 421.Atomic nuclei, masses of, 18.determination of, 459.mination of, 404.447.of, 441.respiratory exchange of, 446.transmutation of, 19.light, table of radioactive trans-formations of, 28.Atomic weight of protoactinium, 16,146.Atoms, partition function for, 71.Aurantin, 448.Auroglauoin, 447.Auxins, 425.of thorium, 146.determination of activity of, 427.Azafnn, structure of, 293.Azafrinals, 296.Azomethane, decomposition of, 100.Bacteria, purple, carotenoids from,purple and red sulphur, pigmentBacteriochlorophyll, 396.Bacterio-methyl phaeophorbide a, 397.Barium alloys with aluminium, 177,305.from, 396.205.with silver, 174.with tin, 179.Beans, djenkol, amino-acid from, 418.Beetroots, sugar, dry rot and h a r trot of, as boron-deficiency dis-eases, 440.Benzaldehyde, condensation of, withglucose, 279.Benzene, structure of, 242.valency angles in, 126.entropy of, 89.Benzene, hemchloro-, structure of,nitro-derivatives, colorimetry of,p-dinitro-, structure of, 232.8-Benzhydryl- 1 -naphthoic acid,methyl ester, action of, withphenyl-lithium, 249.Benzophenone, valency angles in, 133.Benzophenoneoxime picryl ether,Beckmann transformation of,103.Benzoquinone, structure of, 231.Benzo ylauramine - G as indicator, 45 6.Benzthiazole, thiol-, as analyticalBenzyl halides, valency angles in,2 : 4-Benzylidene sorbitol, 280,Beri-beri, human, treatment of, 403.3-Benzyl-3 : 4 : 5 : 6-tetrahydro-norharman, 3-m-hydroxy-, 342.Beryllium, allotropy of, 204.nuclear mass of, 17.determination of, 462.Beryllium alloys with copper, iron,and nickel, 203.Beryllium bromide and chloride,dipole moments and structure of,137.195.477.reagent, 457.135.carbide, structure of, 206.Beryx decadactylus.See Goldfish.Bleaching powder, constitution of,158, 195.Binnite, structure of, 208.Biochemistry, 400.Biotin, 431.cis- and trans-Bis-anti-benzylmethyl-glyoximes, 161INDEX OF SUBJECTS. 515Bisethylenediaminoplatinous salts,configuration of, 163.Bismuth, detection of, 472,474.Bismuth alloys with calcium, 172.with lithium, 173.with thallium, 167, 205.‘‘ Bohemium,” 147.Boracite, structure of, 214.Borates, structure of, 214.Boric acid, structure of, 213.Boron in plants, 440.detection of, 473.Boron carbide, structure of, 206.trichloride, dipole moment andstructure of, 136.trifluoride, thermal analysis ofmixtures of argon and, 159.trioxide, crystalline, 214.Brass, structure of various forms of,181.Bromine, reaction of, with hydrogen,90.Bryophyllurn crenatium, growth in-hibitor from leaves of, 426.Bufotenine, synthesis of, 345.Butadiene, polymerisation of, inpresence of lithium, sodium, andmetal alkyls, 258.see.-Butyl iodide, decomposition of,102.a-Butyric acid, determination of, 478.Cactus alkaloids, 336.Cadmium, isotopes of, 16.detection of, 469.determination of, 457.Cadmium alloys with copper, 174.with lithium, 172, 204.with magnesium, 175.Cadmium bromide, structure of, 188.Cssium, detection of, 473.Cssium alloys with sodium, 172.Cssium nitrate, structure of, 218.Calciferol, 405.Calcium, detection of, 470.determination of, 464.Calcium alloys with bismuth, 172.with gold, 172.with lead, 180.with silver, 174.sulphate, urea compound, 223.Calcium boride, structure of, 206.Calorimeter, 114.Camera, Weissenberg, 194.Canavanine, 418.Caoutchouc, a- and fl-foms of, 261.soluble, insoluble, and vulcanised,Capsanthin, 301.Capsicum annuum.See Pepper, red.Capsorubin, 301.Carbides, structure of, 205.264.Carbocyclic compounds, 305.Carbohydrates, 272.structure of, 235.Carbon black, structure of, 207.Carbon subfluoride, structure of, 207.monoxide, entropy of, 88.adsorption of, by palladium oxide,reaction of, with nitrogen mon-dioxide, structure of, 225.Carbonyl compounds, determinationof, 476.sulphide, explosion limit for oxid-reaction of, with water, 103.cis-dl-3-Carboxy - 1 : 1 - dimethylcyclo-propane-2-propionic acid, syn-thesis and resolution of, 321.Carboxyl group, structure of, 228.Carenes, 32 1.Carica papaya, caricaxanthin from,296.Carlic acid, 447.Carlosic acid, 447.Carolic acid, 447.Carolinic acid, 447.Carotene, detection of, 478.a-Carotene, 292.#&Carotene, 292.Carotenoids, 291.p-Carotenone aldehyde, 293.Carvomenthols, 320.Carvomenthones, 320.Caryophyllenes, 325.Catalysis, heterogeneous, 116.Catalysts, activation of, by secondarysolid, surface structure of, 116.Cedrene, 329.Cellulose, structure of, 237, 284.distribution of, in algq 449.Cerium tungstate, structure of, 218.Chabazite, structure of, 216.Chain growth, mechanism of, 250.Chemotherapy, 421.Chitin, 289.Chitose, 289.Chloral, effect of iodine on decom-Chlorates, determination of, 467.Chlorin e, 366.alkaline degradation of, 368.reduction of, 375.Chlorin f, 386.Chlorine, determination of, in water,480.Chloroform, valency angles in, 128.Chlorophyll, 362.111.on zinc chromite, 111.oxide, 102.ation of, 101.constituents, 119.position of, 102.formulae for, 380.allomerisation and phase test for,385516 INDEX OF TBJECTS.Chlorophyll derivatives, conversionChlorophyll a, 374.structure of, 390.partial synthesis of, 394.optical activity of, 391.Chlorophyll b, 395.optical activity of, 391.Chlorophyllides, 364.isoChlorophyllins, 367.Choline esterase, 424.Chromates, detection of, 472.Chromium, determination of, 462.Chromium alloys with aluminium,Chromium carbide, 202.Chrysene, structure of, 230.Cinchene, 337.Cinchona alkaloids, 337.Cinnamic acid, methyl ester, cis-trans-isomerism of, 108.ciscinnamic acid, methyl ester, iso-merism of, 102.Citric acid, formation of, by moulds,444.Clays, minerals of, 216.Clove oil, caryophyllenes in, 325.Clovene, 327.Clovenic acid, 327.Coal, porphyrins in, 398.Northumbrian, gallium and ger-manium in, 165.Cobalt, 4-covalent, configuration of,160.detection of, 470, 474.determination and separation of,Cobalt alloys with aluminium,Cobalt silicide, 202.sulphide, precipitated, compositionsulphoxylate, 153.Coir, structure of, 238.Colloids, X-ray and electron methodsapplied to, 195.Colusite, structure of, 208.Conqerm, manganese in, 439.Convolvamine, 340.Convolvicine, 340.Convolvidine, 340.Convolvine, 340.Convolvulus pseudocantabricus, allk-Copper, 4-covalent, configuration of,detection of, 468, 472.determination and separation of,withgold, 171, 184.witch magnesium, 171, 199.of, into porphyrins, 368.178.nitrides, 201.463.178.and properties of, 153.aloids of, 340.162.458.Copper alloys, 173.Copper alloys with silver, 17 1.Copper compounds, co-ordination,220.Copper oxide, structure of, 210.catalytic, activation of, byaluminium and chromiumoxides, 1 19.with tin, 171.withzinc, 171.silicide, structure of, 203.sulphate pentahydrate, structure of,Coproporphyrin, 398.Corallim o@cinalis, constituents of4-Corynanthine, 341.Cotton plants, utilisation of am-o-Cresolphthalein as indicator, 455.Crocetin, 303.traw-Crocetin dimethyl ester, thermalCrotonic acid, hydrogenation of, inCrystallography, 193.Crystals, physics of, 181.chemistry of, 197.plasticity of, 191.molecular, 223.real, properties of, 189.222.extracts from, 449.monium salts by, 436.degradation of, 303.presence of platinum, 118.Cristobalite, structure of, 188.Cucurbi t axan t hin , 2 9 6.Cucurbitene, 296.Curare alkaloids, 351.Curine, 351.Cyanide ion, structure of, 217.Cyanide radical, partition functionCyanides, determination of, in water,483.Cyanogen bromide as volumetricstandard, 452.Cyanomaclurin, 250.Cyanuric triazide, structure of, 233.Cybotactic groups, 242.Cymarose, structure of, 273.of, 74.Dauricine, 352.Decahydronaphthalenes.See De-calins.Decalins, 307.Decalols, 308.Decalones, 308.Decane, structure of, 242.Decoic acid, w-hydroxy-, poly-amides and polyesters from, 267,268.De-e t hylphylloery t hrin, 3 82.De-ethylpyrroporphyrin, 382.isoDehydroandrosterone, 409.Deh ydronorcaryoph yllenic acid, 3 2 5.Deoxophylloerythrin, 3 98INDEX OF SUBJECTS. 517Deoxophylloerythrin, synthesis of,Deoxoph ylloery t hro -ze tioporphyrin,Deuterium (heawy hgdrogen), separ-377.398.ation of, 40.properties of, 44.entropy of, 88.zero-point energy of, and itsreactions, 98.interchange reactions with, 43.exchange of, with hydrogen, byenzymes, 49.catalysis in reactions with, 119.in study of acid-base catalysis, 49.reduction of ethylene by, 118.determination of, 42.Deuterium compounds, 47.spectra of, 64.Deuterium oxide (heavy water), 45.properties of solutions in, 48.Deuterons, disintegration by, 122.Dextrins, Schardinger’s, 287.Diamine-fast-Bordeaux-GBS, 456.Diamine-fast-violet-BBN, 455.Diamonds, optical and photoelectricproperties of, 184.1 : 2 : 5 : 6-Dibenzanthracene, opticaland magnetic properties of, 230.Dibenzyl, structure of, 231.Dichromates, detection of, 472.Dickite, synthesis of, 217.Dicyclic compounds, 306.4 : 5-Dideuterocoprostanone, 48.Dideuteromalonic deuteracid, 48.Diems, conj ugated, polymerisa tionDiethylacetal, acid hydrolysis of,Diethylmercury, dipole moment andDigitalose, structure of, 272.heteroDihydrocinchonine, 33 8.22 : 23-Dihydroergosterol, 406.Dihydrolysergic acid, action ofpotassium hydroxide on, inhydrogen, 348.a- and fl-Dihydrolysergols, 346.Dihydrophzeophorbide, formationand properties of, 384.fir -Dime t h ylbu tadiene, polymeridesof, 257.6 : 7- Dimethyl- 9 -d-1‘-lyxitylisoallox-azine, 358.Dimeth ylphEopurpurin, 7, 3 8 7.6 : 7 - Dimethyl - 9 -d- 1‘-ribitylwoallox-azine, 356.Dimethylthallium halides, structureof, 220.Diosphenol, catalytic hydrogenationof, 321.Diphenic acid, 4 : 6 : 4‘ : 6‘-tetra-bromo-, racemisation of, 247.of, 256.104.structure of, 137.Diphenic acid, 6-nitro-6’-amino-, 6‘-acetyl derivative, resolution of,248.Diphenyl, and its compounds, 246.Diphenyl ether, pp’-diiodo-, oxygenvalency angle in, 131.ethers, oxygen valency angle in,130:sulphides, sulphur valency anglein, 130.sulphoxide, valency angles in, 134.Diphenylbenzidinesulphonic acid,sodium salt, as indicator, 455.Diphenylcarbazone as indicator, 455.d- and I-Diphenyldinaphthy~llenes,ua -Diphenyle thylene derivatives ,valency angles in, 134.Diphenylmercury, and dibromo-,dipole moments and structure of,137.Diphenylmethane, valency angles in,133.ay - Diphenyl- y - naphthylallene - a -carboxylic acid, carboxymethylesters, 243.Diphenylsulphone, valency angles in,133.Dipole moments, calculation ofvalency angles from, 126.1 : 2-3 : 5-Diisopropylidene gluco-furanose, 279.d-glucofuranose, 278.d-mannofuranose, 278.2 : 3-5 : 6-Diisopropylidene methyl-mannofuranoside, 2 7 8.2 : 3-4 : 6-Diisopropylidene a-me thylmannopyranoside, 2 78.2 : 3-4 : 6-Diisopropylidene Z-sorbo-furanose, 279.1 : 2-3 : 5-Diisopropylidene xylo-furanose, 279.Dithionates, formation of, fromsulphites, 150.4 : 4’-Ditolyl, 2 : 6-dibrorno-3 : 3‘-diamino-, partial resolution of,247.p-Divinylbenzene, polymerisation of,263.polymerisation of mixtures ofstyrene and, 261.Djenkolic acid, 418.Dodecahydrobenzanthracene, struc-ture of, 230.Drop reactions, 47 1.Drought, resistance of plants to, 435.243.1 : 2-5 : 6-Diisopropylidene2 : 3-5 : 6-DiisopropylideneEarths, rare, activation of, 26.alloys of, 205.separation of, 462518 INDEX OFEchinenone, 304.Echinus esculentus.See Sea urchin.Edestin, structure of, 241.Electrical conductivity of alloys, 166.Element No. 61, 139.No. 85, 141.No. 87, 141.No. 93, 147.Elements, isotopic constitution of, 15.transmutation of, by bombard-ment, 19.4-covalent, 160.Enargite, structure of, 209.Energy, mountain model of, 92.values of, from spectra, 75.rotational, of polyatomic molecules,Entropy of mixed isotopes, 80.of monatomic gases, equation for,Epicinchonine, 338.Equilibrium constants of reactions,86.Ergine, 346.Ergobasine, 349.Ergoclavine, 350.Ergometrine, 349.Ergometrinine, 3 5 0.Ergostetrine, 349.Ergot alkaloids, 345.Ergotamine, 345.Ergotaminine, 345.Ergotinine, 345.+Ergotinine, 346, 350.Ergotocine, 349.Ergotoxine, 345.Erythritoldipyruvic acid, rotationdZ-Eserethole, synthesis of, 343, 344,Eserine, 343, 423.Z-Eserine, synthesis of, 344.Ethane, hmchloro-, structure of, 236.s-diiodo-, structure of, 227.Ethoxyphaoporphyrin a,, 389.Ethyl azide, explosion of, 101.chlorophyllide, 364.1 O-ethoxyphaophorbide, 388.Ethylene, vibration-rota t ion spec-trum of, 61.adsorption of, on manganese chro-mite, 111.hydrogenation of, on nickel, 118.reduction of, by deuterium and byhydrogen, 1 18.and its homologues, as growthsubstances, 430.dichloride, polymeride from sodiumtetrasulphide and, 270.diiodide, reaction of, with iodine,103.E thylhydrocupreine, hydroxy -,therapeutic properties of, 423.55.66.and structure of, 122.423.IUB JECTS.4 : 6-Ethylidene a-d-glucopyranose,10 - Ethylphenoxarsine - 2 - carboxylicEucolloids, 260.Excelsin, structure of, 241.Extraction apparatus, Soxhlet, modi-280.acid, resolution of, 249.fied, 479.Fats, conversion of, into carbo-Felspars, structure of, 216.Ferricyanides, determination of, 467.Ferrocyanides, determination of,Fibres, formation of, from poly-Fibroin, structure of, 238.Films, surface potential of, 106.Flavins, synthesis of, 358.Flavoglaucin, 447.Flavoxanthin, 300.Flax plants, nutrition of, 439.Fhidece, floridoside in, 449.Floridoside, 449.Fluorescein, dichloro-, as indicator,Fluorides, determination of, in water,Formaldehyde, electronic spectrumvibration-rotation spectrum of,polymerisation of, 102.conversion of, to polyoxymethylene,resins from urea and, 269.detection of, 478.hydrates, 417.467.merides, 268.455.483.of, 63.61.265.Frost, resistance of plants to, 432.a- and 6-Fructoheptonic acids,5-Fructonose, 274.cl-Fructopyranose, diacetone deriv-ative, 277.Fructose, conversion of, into anhydro-psicose, 283.d-Fructose, conversion of, into d-sorbose, 283.Fucosterol, 450.Fucoxanthin, 297, 302, 450.Fucus vesiculosus, constituents of, 450.Fulvic acid, 447.Furan, detection of, 478.Furfuraldehyde, condensation of,with sugars, 280.Fasariurn, nitrogen nutrition of, 443.structure of, 273.determination of, 476.Gadidm, glycogen from livers of, 288.d-Galactopyranose, diacetone deriv-ative, 277INDEX OF SUBJECTS.51 9Gallium, structure of, 205.Gallium alloys with aluminium, 178.Gases, flue, of power stations, re-moval of sulphur from, 150.Gelatin, amino-acids in, 418.Germanium from Northumbrian coal,165.Glass, structure of types of, 215.Gluconic acid, formation of, byGlucosazone, structure and methyl-Glucose, mutarotation of, 104, 105.action of barium hypobromite on,condensation of benzaldehyde with,action of bromine on, 277.benzoates, 272.&acetone, 275.determination of, 476.from Northumbrian coal, 165.with copper, 174.detection of, 469, 473.moulds, 445.ation of, 276.277.279.Glutathione, constitution and syn-Glycogen from fish livers, 288.Glycylglycines, structure of, 238.Glyoxal, decomposition of, 102.Goethite, structure of, 213.Gold, solubility of, in mercury, 177.detection of, 474.Gold alloys with calcium, 172.with copper, 171, 173, 184.with manganese, 201.with mercury and tin, 167.with tin, 179.Goldfish, astacene in, 300.Graminin, structure of, 289.Graphite, structure of, 206.Growth substances, 425.Guanidinium halides, structure of,thesis of, 419.228.Hamin, oxidation of, 369.Haemopyrrole, 3 7 0.Hafnium, nuclear moments of, 16.Halides, structure of, 209.Halogens, determination of, 466.Hamamelose, structure of, 274.Hauyn, structure of, 216.Heat of adsorption, 113.Hemicolloids, 260.Heptane, structure of, 242.spiroHeptane, &amino-, rotation andstructure of, 125.Heteroauxin, 426.initiation of roots by, 427.Heterocyclic compounds, 330.Heteropoly-acids, structure of, 220.Heusler’s alloys, ferromagnetic, struc-ture of, 202.Hexadeuterobenzene, 47.Hexamethylenetetramine, structureEexamethylethane, structure of, 226.cycZoHexane, structure of, 242, 306.cis-cgcZoHexane -1- acetic - 2 -propioniccploHexane-1 : 2-diacetic acid, 308.H’exoic acid, e-amino- , polymerice-Hexolactone, polymeric, 267.Holmium, nuclear moments of, 16.Homocaronic acid, cis- and trans-d-Homopilopic acid, synthesis of, 332.Homosantenic acid, 324.Hormones, corpus luteum, 410.sex, 408.testicular, 408.Hydrargillite, structure of, 212.Hydrazine, structure of, 136.Hydrindanes, 310.5 -Hydrindanol, 3 1 2.Hydrindan-4-one, 311.ck-6-Hydrindanone, 312./3-Hydrindanones, reduction of, 309./3-HydrindanylaminesY 3 11.Hydrocalumite, structure of, 213.Hydrocarbons, oxidation of, 101.Hydrocyanic acid, molecules, inter-nuclear distances in, 65.detection of, 474.Hydrogen, atoms, recombination of,entropy of, 88.heat of adsorption of, on copper,on zinc oxide, 114.adsorption of, on promoted am-on chromium oxide, 110, 112.on zinc oxide, 110.zero-point energy of, and its re-actions, 98.reduction of ethylene by, 118.reaction of, with bromine, 90.with oxygen, 100.atomic, partition function for, 71.ortho- and para-, transition of, 103.Hydrogen peroxide, dipole momentsolid, structure of, 225.decomposition of, in aqueoussulphide, formation of, from itsvibration-rotation spectrum of,of, 227, 331.as analytical reagent, 462.acid, synthesis of, 308.amides from, 267.forms, 321.99.platinum, and tungsten, 113.monia catalysts, 111.and structure of, 136.solutions, 105.elements, 100.61.Hydroxides, structure of, 212.Rydroxyl, partition function of, 74.Hypophosphite group, structure of,218520 INDEX OF SUBJECTS.Illinium, 139.Indicators, 455.Indium, detection of, 472.Indium alloys with copper, 174.Indole-3-acetic acid, and its deriv-atives, as growth substances, 429.Indole-3-~-propionic acid as growthpromoter, 429.Inorganic analysis, 451.meso-Inositol as growth.promotingfactor, 275.Insulin, crystalline, structure of, 240.Inulin, hydrolysis of, 288.Iodides, structure of, 207.determination of, in water, 484.Iodine, reaction of, with methylchloride, 95.Iodine oxides and sulphates, 159.Ionic compounds, 209.Ions, complex, 217.Iridium, isotopes of, 15, 16.Iron, solubility of, in mercury, 177.detection of, 472.metallic, detsrmination of, in pre-sence of iron salts, 461.Iron alloys with aluminium, 203.with tin, 180.with tungsten, 201.Iron carbides, 201.oxide, catalytic, activation of,by alumina, 119.Isoprene, trimeride of, 257.Isotopes, 15, 40.with silver, 175.with potassium, 99.entropy of mixtures of, 80.radioactive, use of, as indicators,52.Jeremejewite, structure of, 214.Kaolinite, synthesis of, 217.Keratin, structure of, 238.a-Keto-acids, determination of, 478.5-Ketofructose, 274.5-Ketogluconic acid, 277.2-Ketogulonic acid, preparation of,Kinetics, chemical, 89.Kryptopyrrole, 370.Kryptoxanthin, 296.280.Lactoflavin, 354, 404.Lamiruzria digitata, cellulose from,Lanthanum, nuclear moments of, 16.Larch, European, polysaccharideLattice constants of elements, 200.Lead, determination of, in water, 484.determination and separation of,449.from, 291.458.Lead alloys, 180.Lead diammonium &chloride, struc-Lepidocrocite, structure of, 213.Leucoanthocyanidins, 249.Leucoanthocyanins, 249.Levosin, hydrolysis of, 288.Lipins, formation of, by moulds, 446.Liquids, structure of, 242.Lithium alloys, 204.with bismuth, 173.with cadmium, 172.with lead, 180.with mercury, 176.with silver, 172.with thallium, 172.with tin, 179.Lithium deuteride and hydride, struc-ture of, 209.nitride, structure of, 206.sulphide monohydrate, structure of,titanate, structure of, 188.Lithosphere, elements in, 143.Liver, oxidation of fatty acids byLobelanine, 340.Lobster, astacene from, 300.Lophiue piscatorius.See Angler fish.Lucerne, hardiness of, 435.Lumichrome, 354.Lumilactoflavin, synthesis of, 354.Lutein, 300.Lycopene, structure of, 392.Lycorine, 338.Lycoris, alkaloids from, 338.Lysergic acid, 346.d-Lysine anhydride &hydrochloride,with antimony, 171.with thallium, 205.ture of, 188.222.slices of, 415.417.Magnesium, detection of, 473.Magnesium alloys, 175.determination of, 465.with aluminium, 167, 177, 204.with copper, 171, 173.with copper and with zinc, 199.with lithium, 204.Magnesium salts, effect of, on growthMagnesium perchlorate as desiccant,halide hezahydrates, structure of,Maize, growth substance from endo-Maize plants, iron in, 440.effect of zinc on " white bud " in,Maja squiwda.See Spider-crab.Malaria, treatment of, 421.of moulds, 441.468.222.sperm of, 427.440INDEX OF SUBJECTS. 521Maleic acid, hydrogenation of, inpresence of platinum, 118.me thy1 eater, cb-tram-isomerism of,108.Maltose, determination of, 476.Mandelic acid, thempeutic use of,Mandelic acid, o-nitro-, resolution of,Manganese, effect of, on plant growth,Manganese alloys with aluminium,Manganese carbide, 202.Mannocarolose, 290.Manuring, effect of, on droughtresistance, 435.Masurium, 142.Matlockite, structure of, 210.Matrine, 354.Mellein, 448.Mendeleef Centenary Lecture, 138.dl-Menthol, resolution of, 321.Menthols, 3 18.Menthylamines, 3 18.Mercuric chloride, structure of, 210.Mercury, parachor of, 164.detection of, 468, 474.determination of, 458.Mercury alloys, 176.with lithium, 204.with thallium, 205.Mesoaetioporphyrin, 398.Mesocolloids, 260.Mesoporphyrin, 373, 398.Metabolism, fat, 414.Metals, structure of, 198.electron theory of, 181.molten, heats of mixture of, 167.Metal coatings, phase structure of,167.Methane molecules, internuclear dis-Methane, nitro-, decomposition of,Methyl alcohol, structure of, 242.425.245.439.178.with gold, 201.oxides, structure of, 210, 211.silicide, 202.tances in, 65.102.determination of, 478.95.chloride, reaction of, with iodine,chlorophyllide, 364.halides, electronic spectra of, 63.iodide, decomposition of, 102.nitrite, decomposition of, 102.Methylamine, decomposition of, 102./3-Methylarabinoside, structure of,Methylene-blue halides, structure of,Methylene chloride, valency angles in,237.234.128.klethylene group, heat of combustionof, 305.3 : 7-Methylenedioxy-10-methylphen-anthridone, 339.2-Methylfucoside, structure of, 237.2-Methylgalactoside 6-bromo -hydrin, structure of, 237.Methyl ketones, detection of, 477.7 -Methyl- 9-d- 1 '-ribitylisoalloxazine,vitamin-B, action of, 357.B -Me t hylumbelliferone as indicator,466.Micro-organisms, polysaccharidessynthesised by, 290.Minerals, porphyrins in, 398.Minioluteic acid, 447.Molecules, asymmetrical top, 55, 83.vibration-rotation spectra of, 61.monatomic, partition function for,71.diatomic, partition function for, 72.polyatomic, classification of, 55, 81.partition function for, 80.complex, partition function for,83.linear, 55, 82.vibration-rotation spectra of, 60.spherical, 55, 82.symmetrical top, 55, 82.vibration-rotation spectre of,Molybdenite, Australian, rheniumfrom, 165.Molybdenum, determination of, 459.Monosaccharides, detection of, 478.Montmorillonite, synthesis of, 2 17.Moulds, biochemistry of, 441.mineral nutrition of, 441.nitrogen nutrition of, 442.production of organic acids byformation of fats by, 446.60.444.Mucic acid, epimerisation of, 277.Muscle, chemistry of, 41 1.Muscone, structure and synthesis of,Myasthenia gravis, 423.Myosin, structure of, 239.Myotin, 423.305.compounds of, with starch, 287.a-Naphthaflavone as indicator, 455.Nephrops norvegicw.See Prawns.Neutrons, mass of, 19.disintegration by, 24.slow, speed of, 26.Nickel, solubility of, in mercury, 177.4-covalent, configuration of, 160.determination and separation of,Nickel alloys with zinc, 202.Nickel compounds, co-ordination.220.463522 INDEX OB SUBJECTS.Nickel carbides, 201.of, 197, 222.and properties of, 153.Nickelohthio-oxalates, 161.Nicotine, detection of, 478.Nitrates, detection of, 471.Nitrazine-yellow as indicator, 456.Nitrides, structure of, 205.Nitrites, unimolecular decompositionNitro-compounds, aromatic, identific-Nitrogen, structure of a- and f i - f o mcarbonyl, decomposition of, 102.sulphate hptahydrate, structuresulphide, precipitated, compositionof, 108.ation of, 475.of, 225.isotopes of, 61.transmutations of, 22.detection of, in water, 481.Nitrogen monoxide (nitrous oxide),entropy of, 88.decomposition of, 100.reaction of, with carbon mon-oxide, 102.dioxide (nitriq oxide), entropy of,88.trioxide, 153.trioxyfluoride, 155.partition function of, 74.Nitrogen organic compounds, cyclic,o -Nitrophenols, determination of, 4’7 8.Nitrosyl chloride, decomposition of,Norcaryophyllenic acid, 325.&-Noreserethole, resolution of, 343.Norhamns, 342.Nortropine, 340.Nosean, structure of, 216.330.102.Oak, structure of, 238.Oats, sodium requirement of, 438.albOcimene, 322.Oc tadeu teronspht halen e, 48.Octalins, 309.bicyclo [2 : 2 : ZI-Octane, 316.bicgclo[O : 3 : 3]-Octanes, 311.bicyclo[2 : 2 : 2]-Octanone, 316.see.-Octyl iodide, rate of inversion of,fl-Octyl nitrite, rotatory dispersion of,Oil shale, porphyrins from, 398.Olefms, polymerisation of, 255.Oospora aurantin, pigments from, 448.Oosporin, 448.Orange trees, chlorophyll-deficient,tmtrnent of, with copper salts,440.Organic analysis, 475.Organic chemistry, 243.96.123.0rphid.iaster orphidianus.See Star-Osctzones, structure of, 276.Osmium, detection of, 472.Oxaletes, anisotropy of, 223.Oxalic acid, formation of, by moulds,fhh.444.dihydrate, structure of, 229.Oxides, structures of, 210.Oxoporphyrins, 383.Oxoyobyrine, 341.Oxygen, isotopes of, 51.valency angle of, in diphenyl ethers,partition function for, 73.heat of adsorption of, on platinum,adsorption of, by nickel, 111.reaction of, with hydrogen, 100.atomic, partition function for, 72.&solved, determination of, inwater, 482.a-Oxycarotene, 292.Ozone, thermal decomposition of, 100.130.113.by platinum, 11 1.by silver, 114.action of, on terpenes, 317.Palladium, isotopes of, 15.parachor of, 164.4-covalent, codguration of, 162.Palladium compounds, co-ordination,Palladium oxide, structure of, 210.Palladodithio-oxalates, 161.Pantothenic acid, 431.Paraffin, liquid, structure of, 242.a-Particles, disintegration by, 19.Partition function, 71.approximations for determinationof, 77.Pectins, 289.Peganine, identity of, with vasicine,333.+Pelletierine, 339.Peltogyne porphyrocardia, leuco-anthocyanidin from heartwoodof, 249.Peltogynol, 250.Penicillium, formation of gluconic acidby, 445.Penicillium Charlesii, polysacchaxidefrom, 290.Penicillium javanicum, fat productionof, 446.Penicillium minio-luteurn, minio-luteic acid from, 447.Pentaerythritol tetrcbphenyl ether,structure of, 226.truns-cycZoPentane-1 : 2-diacetic acid,resolution of, 312.220.products from, 447INDEX OF SUBJECTS.523Pentaxanthin, 304.1 : 2-cycloPentenophenanthrene,Pepper, red, carotenoids from, 301.Pepsin, crystdine, structure of, 240.Percamphoric acid as indicator forPeriodic table, 138.Pernitric acid, 156.Peroxide ions, structum of, 217.Persulphate ions, structure of, 219.Petroleum, rdle of plants in formationof, 399.Phaeanthine, 353.Phaeophorbide, 365.Phaeophorbide a, reduction of, 375.conversion of, into chlorin e, 366.Phmphytin, 366.Phmporphyrin as, 376.Phaeopurpurins, 386.Phenol, determination of, in water,480.Phenylacrylic acid a8 growth pro-moter, 429.Phenyl 8-carboxy-l-naphthyl sulph-oxide, resolution of, 249.a-Phenylethyl chloride, opticallyactive, racemisation of, 245.Phenylpropionic acid as growth pro-moter, 429.Phenyl-m- and -p-toluidines as in-diwtors, 455.Phosphides, structure of, 208.Phosphine.See Phosphorus tri-hydride.Phosphocrerttine, synthesis of, 413.Phosphoglyceric acid, dephosphoryl-ation of, 411.Phosphomolybdic acid as analyticalreagent, 457.Phosphorus, allotropy of, 156.we of radioactive isotope of, inmetabolism investigations, 53.black, crystal structure of, 157.black and red, structure of, 226.detection of, 473.Phosphorus trihydride, explosion limitPhthalocyanines, 360.structure of, 235.Phycomyces, synthesis of growth sub-stances by, 430.Phylloztiaporphyrin, 3 6 9.Phyllobombycin, 377.Phylloerythrin, 376.structure of, 377.synthesis of, 394.Phyllophyllin, 368.Phylloporphyrin, 3 68.oxidation of, 369.reduction of, 370.structure of, 230.double bonds, 318.porphyrins in, 398.for oxidation of, 101.structure of, 373.Phyllopyrrole, 370.Physalienone, 300.Physostigmine.See Eserine.Phytochlorin g, 386.Phytyl alcohol, 364.Pilocarpine, 331.dl-Pilopic acid, 331.Pine, tracheids of, 238.a-Pinene, pyrolysis of, 322.Pinocarnpheols, 320.Pinocamphones, 3 20.Plants, biochemistry of, 425.drought and frost resistance in,nutrition of, 436.nitrogen nutrition of, 436.potassium in nutrition of, 437.boron in, 440.copper and iron in, 439.rubidium in, 438.effect of manganese on growth of,effect of zinc on diseases of, 440.431.439.Plasmocide, 421.Plasmoquin, 421.Platinodithio-oxalates, 161.Platinum, isotopes of, 15, 16.4-covalent, configuration of, 162.Platinum compounds, co-ordination,Platinum metals, determination of,separation of, 469.Pneumonia, treatment of, 422.Poisons, South American arrow, 35 1.Polychloroprenes, 257.Polydecamethylene oxide, 267.Pol yes t erificat ion, 2 6 7.Polymerides, high, 257.properties of, 259.Polymerisation, 250.Polyoxymethylene, formation of, 266.Polysaccharides, 284.Polythionic acids, detection of, 474.Porphin (A), 359.Porphyrins, 359.mineral, 398.Positrons, 34.Potassium, nuclear moments of, 16.radioactivity of, 36.reaction of, with iodine, 99.detection of, 470.determination of, 457, 465.220.460.mixed, 261.condensation-, 265.three-dimensional, 260.Potassium alloys with sodium, 17 1.Potassium dichromate, standardis-permanganate, standardisation of,ation of, 453.453.Potential, surface, of films, 106.Praseodymium, structure of, 205524 INDEX OF SUBJECTS.Praseodymium alloyswith aluminium,178.with magnesium, 175.with silver, 175.Prawns, astacene in, 300.Pregnandione, 410.Probophorbides, 3 7 7.a- and p-Progesterones, 410.Propaldehyde, oxidation of, 102.Propane, chlorination of, 102.Propyl nitrites, decomposition of, 102.Propylamine, decomposition of, 102.Prosti,ge, 423.Proteins, structure of, 238.Protoactinium, 143.Protons, disintegration by, 2 1.Protoporphyrin, 373, 383.Pumpkin, giant, xanthophylls from,Pyramidone, detection of, 478.Pyrophosphate ions, structure of, 219.Pyrroaetiophyllin, 3 69.Pyrroaetioporphyrin, 369.structure of, 372.Pyrroles, substituted, reduction of,Pyrroline, structure of, 330.Pyrroporphyrin, 368.structure of, 371.at.wt. of, 16, 146.296.331.Quanta, vibrational, excitation of,in relation to activation, 97.Quantum theory in relation tochemical kinetics, 89.Quinine, 42 1.isoQuinoline derivatives, 336.demethylation of, 337.Racemic acid, activation of, 244.Radicals, free, in solution, 105.Radioactive nuclei from neutronRadioactivity produced by neutrons,Radium-E, P-ray spectrum from, 34.Rays, cosmic, 36,&Rays, disintegration with emissiony-Rays, disintegration by, 28.X-Rays, crystal analysis by means of,Reactions, atomic, 97.~ONC, calculation of activationenergy of, 95.organic, 108.in solutions, 103.bakelite, 270.fomaldehyde-urea, 269.bombardment, 24.table showing, 31.of, 32.193.Reagents, 456.Resins, 269.Resins, novolaks, 270.Resorcinol, structure of, 230.Rhenium from Australian molyb-determination of, 460.Rhodjn g, 367.Rhodum, detection of, 474.Rhodopin, 305.Rhodoporphyrin, 368.structure of, 372.isoRhodoporphyrin, 3 9 3.Rhodopurpurin, 305.Rhodoviolascin, 305.Rhodoxanthin, 300.Ricinine, synthesis of, 332.Rickets, treatment of, 406.Ring strain, theory of, 306.Rosa canina and rubiginosa, xantho-Rotation, optical, physical basis of,Rubber, vulcanised, structure of, 264.Rubidium in plants, 438.Rubidium alloys with mercury, 176.with sodium, 171.Rubixanthin, 297.Rubroglaucin, 447.Ruthenium, co-ordination compoundsof, 165.Rutin, structure of, 273.Rutinose, structure of, 273.Rye plants, effects of nitrogen andpotassium on assimilation by,438.thiokol, 270.denite, 165.phyll from, 297.120.Saffron, crocetin in, 303.Salts, hydrated, 221.Sandalwood oil, sesquiterpenes from,terpenes from, 323.Santalenes, 327.Santalols, 327.a-Santalylmalonic acid, oxidation of,317.Santene, 323.Santene glycol, synthesis of, 325.Santenenic acid, 324.Santenic acid, 323.alEoSantenic acid, 324.Fntenol, 323.y-Santenol,” 323.Santenone, 323.Sea anemones, carotenoids from, 304.Sea urchins, carotenoids from, 304.Sebacic anhydride, polymeride of, 267.Selenium, determination and sepam-Selenium dioxide, oxidation in theSensibamine, 350.Sesquiterpenes, 325.327.tion of, 460.terpene series by, 318INDEX OF SUBJECTS.525Silane, explosion limit for oxidationSilicates, structure of, 213.Silicon dioxide (silica), stability offorms of, 215.of, 101.determination of, 467, 483.disulphide, structure of, 209.Silver, nuclear moments of, 16.detection of, 473.determination of, 457.in water, 485.with aluminium, 167.with lithium, 172.with mercury, 176.Silver cyanide, structure of, 188.iodides, structure of, 188, 207.mercury iodide, structure of,nitrate, urea compound, 223.Sisal, structure of, 238.Sodium, ortho-salts of, 158.deterrmnation of, 466.Sodium alloys with caesium, 172.with potassium, 171.with rubidium, 171.Sodium carbonate for analyticalpurposes, 452.hydrogen carbonate, structure of,218.sulphate decadeuterate, transitiontetrasulphide, polymeride fromethylene dichloride and, 270.thiosulphate, standardisation of,454.Sophora JEavescerts, alkaloid from,354.d-Sorbose, conversion of d-fructoseinto, 283.2-Sorburonic acid; 277.Spectra, determination of thermo-dynamic constants from, 66.Silver alloys, 174.188.point of, 47.atomic, 53.electronic, 62.extreme ultra-violet, Lyman con-molecular, diatomic, 53.tinuum k, 63.polyatomio, 83.rotation, 55.vibra tion-ro ta tion, 5 6.Spectroscopy, 53.Spider-crab, astacene from, 300.“Spot ” tests, 471.Stannite, structure of, 209.Star-&h, astacene in, 300.Starch, structure of, 237, 285.oak and walnut, 291.Starch dextrins, 286.Steel, structure of, 201.Stereochemistry, 243.Steric factor, 106.Stilbene, cis-tram-isomerism of, 108.Stilbene, 2 : 4 : 6-trinitro-, action ofStrontium alloys with silver, 174.Styrene, polymerisation of mixturesof p-divinylbenzene and, 261.Sucrose, determination of, 478.~suSucrose, structure of, 273.Sugar, cane-, inversion of, 105.Sugars, structure of, 235.compounds, 277.Sulcataxanthin, 304.Sulphantimonates, structure of, 208.Sulphates, determination of, 467.Sulphides, structure of, 208.Sulphohalite, structure of, 218.Sulphur, structure of, 148.bromine on, 244.with tin, 179.condensation of, with carbonylin water, 482.valency angle of, in diphenylrecovery of, from waste gases, 149.plastic and rhombic, structure of,Sulphur monochloride, structure of,sulphides, 130.225.152.monoxide, preparation of, 150.tetroxide, 151.Surface chemistry, 109.Swedenborgite, structure of, 218.d- and E-Talomucic acids, 277.d-Talose, condensation of, withacetone, 278.Taraxanthin, 300.Telluric acid, structure of, 213.Tellurium, effect of, on properties oflead, 180.Teloidine, 3 3 9.Teresantalic acid, 327.Terpenes, 316.Terrein, 448.Testosterone, 409.2 : 3 : 4 : 5-Tetra-acetyldetermination of, 460.aldehydo-d-galactose, 6-i0do-, action .ofacetic anhydride and zmcchloride on, 275.Tetra-acetyl p-arabinose, rotation of,123.Tetradehydroyohimbine, alkali scis-sion of, 342.6 : 7 : 9 : 10-Tetradeuterostearic acid,48.Tetradymite, structure of, 209.Tetrahydrodicyclohexadiene, 3 15.Tetrahydro -a-dicyclopentadiene, 3 14.Tetrahydroyobyrine, structure of,n- and %ao-Tetrandrines, 353.aayy-Tetraphenylallene, valency340.angles in, 134526 ENDEX OF SUBJECTS.Te t raphenylmethane, structure of,Thallium, determination of, 456, 457.Thallium alloys, 205.with bismuth, 167.with lithium, 172.with magnesium, 175.with mercury, 176.data, 84.226.Thermodynamic constants fromThianthren, dipole moment of, 131.Thiochrome, 402.Thiocyanates, valency angle of sul-phur in, 131.Thiocptis wiolacea, pigment from," Thionalide " as analytical reagent,Thiophen, detection of, 478.Thiosulphurous acid, structure of,Thorium, at.wt. of, 146.Thorium-C, ,%ray disintegration of,33.Tiger lily, xanthophyll from anthersof, 304.Tin, detection of, 472.Tin alloys, 179.with arsenic, 205.with copper, 171, 174.with gold and mercury, 167.with magnesium, 175.spectra, 86.397.456.152.determination of, 460, 462.Titanium, detection of, 472.Titanium alloys with aluminium,Tomato plants, potassium in nutri-Transmutation, nuclear, 19.Trideuteracetic deuteracid, 48.Triethanolamine, nitrogen valencyTriethylene sorbitol, 280.Trimeth ylphtinum chloride, struc -1 : 3 : 5-Triphenylbenzene, structureTriphenylchloromethane, valencyTriphenylmethane, valency angles in,Trithionate ions, structure of, 219.Tritium, 50.Tropan derivatives, 339.Tropinone, 339.Tubocurarine, 351.Tung trees, effect of zinc on " bronz-Tungsten, separation of, 462.Tungsten alloys with iron, 201.Tungsten bronzes, structure of, 188,178.tion of, 438.angle in, 134.ture of, 220.of, 230.anglesin, 134.134.ing " in, 440.211.Uranium, isotopes of, 15.Uranium minerals, separation ofprotoacthiurn from, 144.Urea, structure of, 227.production of, from peptone byrate of formation of, 104.resins from formaldehyde and, 269.determination of, in water, 481.Urinary tract, treatment of infectionsmoulds, 444.of, 425.Vacchcn, constitution of, 272.Valency angles, calculation of, froindipole moments, 126.Vanadium compounds with por-phyrins, 398.Vanadium, determination of, 461.determination and separation of,462.Vanadous ammonium sulphate asanalytical reagent, 461.Vapour pressure of amalgams, 177.Vasicine, identity of, with peganine,333.Vibrators, coupled, theory of, 120.Victoria-blue-BX, 455.Violaerythrin, 304.Violaxanthin, 300.Vitamin-B,, 401.Vitamin-B,, 403.Vitamin-C, 404.Vitamin-D, 405.Vitamin-E, 407.Volumetric analysis, standards for,linear, 121.452.Walden inversion in sugars, 280.Water, structure of, 242.vibration-rotation spectrum of, 61.entropy of, 88.odour and taste of, 479.organic matter in, 481.biological oxygen demand of, 482.analysis of, 479.detection in, of nitrites, 481.determination in, of chlorine, 480.of cyanides, 483.of fluorides, 483.of iodides, 484.of lead, 484.of oxygen, 482.of phenol, 480.of silver, 485.of sulphates, 482.of urea, 481.of zinc, 484.Weighing, 451.Weights, storage of, 451.Whale oil, astmene in, 300INDEX OF SUBJECTS.527Wheat plants, potassium in nutritionof, 438.spring and winter, respiration of,433.Witzschia cbsterizcm, replacement ofpotassium by rubidium in, 439.Xanthophylls, 296.Xylran, structure of, 288.Yeast, growth substance of, 431.Yohimbine, 340.polysaccharides of, 2 9 1.Zertxanthin, 297.Zeolites, structure of, 216.Zinc, isotopes of, 16.effect of, on growth of Aspergilluson diseased plants, 440.catalytic, structure of, 116.determination of, 464.in water, 484.Zinc alloys with aluminium, 204.with copper, 171, 173.with lithium, 204.with magnesium, 199.with nickel, 202.oxide. structure of, 210.Iziger, 442.Zinc chromite, adsorption by, 114.Zirconium, determination of, 460,462London built VACUUM EVAPORATORSIn double and quadruple effect, plus Thermo Re-compression, the world’s mosteconomic system. Jahn’s British and U.S. Patents. Numerous large installationsconcentrating various trade liquors operating in London and Provinces. Steam jetproduces Vacuum, its exhaust heats,FILTER, FOR OUTPUT,EJECTOR JETS, ‘‘ FARMA” MILKJ A H N P L A N Tfor starch, from cassava-tapioca roots, potatoes, etc.MACHINERY IN STOCKfor cocoa, sweets, chemicals. Filling and Packaging.washable pulp medium.cooling by vacuum. CONDENSING P L A N T .-CERAMIC COLOURSGLAZES & MATERIALSENAMELS FOR IRONHARRISON & SON (HANLEY) L?pPhoenix Chemical Works,HANLEY, S T O K E - O N - T R E N T , ENGLANDTelephone: HANLEY 5313 (7 lines). Telegrams : PHOENIX, HANLEY~ CHEMICAL SOCIETY’ MEMORIAL LECTURES(Suitable for preseniation as school prizes)VOLUME I, 1893-1900. (Reproduced by a photo-lithographic process.)Price 10s. 6d. Postage 6d.VOLUME 11, 1901-1913. (Reproduced by a photo-1 it h ographic process. )Price 8s. Postage 6d.VOLUME 111, 1914-1932.Price 6s. Postage 6d.All bound in blue cloth.Publishers : THE CHEMICAL SOCIETY, BURLINGTONHOUSE, PICCADILLY, LONDON, W.

ISSN:0365-6217    

DOI:10.1039/AR9353200513

出版商:RSC    

年代:1935

数据来源: RSC