ISSN:0365-6217    

DOI:10.1039/AR94946FP001

出版商:RSC    

年代:1949

数据来源: RSC

摘要:

vi CONTENTSERRATUM.VOL. 45, 1948.Page128 reference 44 fm P. Oxley and W. F. Short read P. Oxley,M. W. Partridge, and W. F. Short

ISSN:0365-6217    

DOI:10.1039/AR9494600006

出版商:RSC    

年代:1949

数据来源: RSC

摘要:

ANNUAL REPORTSON THEPROGRESS OF CHEMISTRY.GENERAL AND PHYSICAL CHEMISTRY.THIS Report marks a transition stage. Reports for recent years aimedat a comprehensive stock-taking of work carried out over a period of yearsin selected topics. In future Reports, the aim will be to give a generalperspective of the main developments during the year reviewed. The paperscited have been selected so as to give preference to those likely to interestchemists outside the immediate circle of specialists. Since the generalplan is to give an account of trends in the various branches of Chemistry,the treatment of individual topics is more by reference and much less self-contained than hitherto. Topics under active controversy have beenincluded.As in other transition states, a certain time-indeterminacy is inevitablein the present Report.The range of publication dates covered is furtherwidened by the fact that publications made during the war in manyEuropean countries have in some cases only recently become available toBritish readers. Sections 11 and 12, on the subjects of which there hasbeen much recent discussion and some controversy, are more self-containedand are dealt with separately. The remainder of the Report includestopics from publications which in the main have been abstracted betweenAug. 1948 and July 1949, inclusive, though it is not wholly restricted tothis field. A. R. U.1. GENERAL THERMODYNAWCS AND THE EVALUATION OFTHERMODYNAMICAL FUNCTIONS FOR GASES.1. A number of theoretical papers have been published which refer tothe general thermodynamics of irreversible processes. Irreversible ‘‘ entropyproduction ” in processes such as viscous flow and thermoelectric effectsare discussed by various authors.1 One main stimulus to theories of irrever-sible processes arises from the success of the thermal-diffusion method ofseparation of isotopes.K. Schafer suggests that in the separation of gasmixtures by thermal diffusion the entropy and heat conductivity of thecomponents rather than their molecular weights are of controlling importance.Some experimental evidence is described for nitrogen-hydrogen mixturesR. C. Tolman and P. C. Fine, Rev. Mod. P h y s h , 1948, $30, 51; I. Prigogine,‘‘ gtude thermodynamique des Phhomknes irreversibles,” Dunod, Paris, 19478 GENERAL AND PHYSICAL CHEMISTRY.containing dinitrogen tetroxide.2 Other work on thermal diffusion includesgeneral theoretical calculations,3 and measurements of the Soret effect inaqueous solutions of sucrose.* The rate of entropy increase in anelasticprocesses has been discussed by C.Eckart.5 Experiments on " steady-state " irreversible processes include reports on the separation of com-ponents by thermo-osmosis of liquids through porous materials and ofgases through a membrane. Thermo-molecular pressure differences havebeen measured in hydrogen, deuterium, helium, and neon at pressuresranging from 0.01 to 0.09 em. and temperature gradients from 390" to roomtemperatures.* Thermal-diffusion potentials have been studied in cellswith silver/silver halide electrodes, and various electrolytes in which atemperature gradient was maintained.g The biological implications ofirreversible processes have been discussed.l*2.A second main stimulus in the study of the general thermodynamicsof irreversible processes arises from the remarkable thermo-mechanicalproperties of liquid helium below the ?,-point .I1 Papers include a deductionof London's relation for the " fountain " effect,12 experiments on thedifferences in behaviour between 3He and 4He atoms in the liquid,13 andobservations and calculations on " second sound " in liquid helium inrelation to the high thermal conductivity of He 11.14 A high absorptioncoefficient has been observed in liquid He, near the h-point, with ultrasonicvibrations. l53.Finally, the bold suggestion of utilising the heat gradient from thesurface to the interior of the earth as a source of power by means of thermo-artesian wells l6 may be noted.4. In the systematic evaluation of thermodynamic functions for im-portant chemical species by calorimetric and spectroscopic means new data2 K. Schafer, Angew. Chem., 1947, 59, A , 83.I. Prigogine, Physica, 1947, 13, 319. 6 . R. de Groot, J . Phys. Radium, 1947, 8,129, 188.4 J. van Dranen and F. Bergsma, Physica, 1947,13, 558.6 C. Eckart, Physical Rev., 1948, 73, 373.6 H. P. Hutchinson, I. S. Nixon, and EL. G. Denbigh, Paraday SOC. Discussions, 1948,7 K. G. Denbigh, Nature, 1949, 163, 60.8 A. van Itterbeck and E. de Grande, Physica, 1947, 13, 422.* H.J. V. Tyrrell and G. L. Hollis, Trans. Paraday SOC., 1949, 45, 41 I .10 I. Prigogine and J. M. Wiame, Experientia, 1946,11, 11.11 Cf. Repts. Progr. Physics, 1949, 12, 280.12 S. R. de Groot, Physica, 1947, 13, 555.l3 H. A. Fairbank, C. T. Lane, L. T. Aldrich, and A. 0. Nier, Physical Rev., 1948,73, 256, 729; J. G. Daunt, R. E. Probst, and H. L. Johnston, ibid., p. 638.l 4 V. Peshkov, J . Phys. U.S.S.R., 1946, 10, 389; W. Band and L. Meyer, PhysicalRev., 1948, 73, 226 (cf. The statistical mechanical calculations of W. Band, J . Chem.Physics, 1948, l$, 343); D. V. Gogate and P. D. Pathak, Proc. Physical Xoc., 1947,59, 457; L. Tisza, Physical Rev., 1947, 72, 838; R. B. Dingle, Proc. Physical Soc.,1949, 62, 154; H. S. Green, Nature, 1948, 161, 391.3, 86-16 J. R.Pellam and C. F. Squire, Physical Rev., 1947, 72, 1245.G. Claude and A. G. Claude, Compt. r e d . , 1949, 228, 544UBBELOHDE : ISOTOPE CHEMISTRY. 9include those for carbonyl chloride,17 ethyl chloride,ls hexaflu~roethane,~~vinyl chloride, bromide, and iodide,20 buta-1 : 2-diene,21 and benzene.22The potential barriers hindering internal rotation about the single C-Cbond is computed to be 4-7 kcals./mole for ethyl chloride, 4.35 kcals./mole €orhexafluoroethane, and 1-6,&0.4 kcals./mole for the methyl group in buta-1 : 2-diene. In solid carbonyl chloride there is evidence of random orient-ation of the molecules at low temperatures, and of “ premelting.” Furthercalculations on the thermodynamics of the internal rotator have beenp~blished.,~ (For other aspects of potential barriers hindering rotation,cf.section 3, 11 .)5. Calculations of equilibria in terms of the thermodynamic functionsand fundamental constants have been published for various systems,including saturated hydrocarbons,24 processes related to butadiene synthesis,25and the system Br, + C1, 2BrC1.26 General methods for the computa-tion of complex equilibria in gaseous systems have been proposed.27Miscellaneous thermodynamical studies of general interest includework on the “ supercritical ” state of liquids, with special reference to theirsolvent power.28 Much of this work has been stimulated by the attemptto grow large crystals of optically pure quartz,29 and by problems 30 in thehydrothermal production of minerals.Equations of state for gases and solids a t pressures up to lo5 atmospheresand at temperatures up to lo* degrees have been studied in connection withdetonation phenomena in explo~ives.~~ A.R. U.2. ISOTOPE CHEMISTRY.1. A large range of stable and radioactive isotopes is potentiallyavailable.32 It is not yet fully clear how far radio-tracer chemistry canl7 W. F. Giauque and W. M. Jones, J. Amer. Chem. Soc., 1948,70, 120.l6 J. Gordon and W. F. Giauque, ibid., p. 1506.l9 E. L. Pace and J. G. Aston, ibid., p. 566.21 J. G. Aston and G. J. Szasz, J. Amer. Chem. SOC., 1947, 69, 3108.22 G. D. Oliver, M. Eaton, and H. M. Huffin, ibid., 1948, 70, 1502.23 J. C. Halford, J. Chem. Physics, 1948, 16, 560.24 33.Zeiss, Oel u. Kohle, 1944, 40, 242.25 F. G. Brickwedde, M. Moskow, and J. G. Sston, J , Res. Nut. Bur. Stand., 1946,26 K. Butkow, Rec. Truv. chim., 1948, 67, 551.27 F. J. Krieger and W. B. White, J. Chern. Physics, 1948, 16, 358.2o R. E. Richards, J., 1948, 1931.37, 263.G. A. M. Diepen, Chem. WeekbZud, 1948, 44, 137; Klinkenberg, ibid., p. 138;W. Tomassi, Roczn. Chem., 1948, 22, 191.29 A. C. Swinnerton, G. E. Owen, and J. F. Corwin, Furuduy SOC. Discumions, 1949,5, 172; G. van Praagh, ibid., p. 338; L. A. Thomas, Nora Wooster, and W. A.Wooster, ibid., p. 341.30 Jean Wyart, ibid., p. 323; R. M. Barrer, ibid., p. 326.31 J. L. Copp and A. R. Ubbelohde, Trans. Furuduy Soc., 1948, 44, 1 ; P. Caldirola,J. Chem. Physics, 1946, 14, 738; S.Paterson, ibid., 1948, 16, 159.32 “ Radioactive and stable isotopes,” Isotope Information Office, Harwell, Didcot,Berks; Proc. Conf. Nuclear Chem., May, 1947, Chem. Inst. Canada; F. A. Paneth,Quart. Reviews, 1948, 2, 9310 GENERAL AND PHYSICAL CHEMfSTICY.be used in any laboratory with good general equipment, and how far thespecial safety precautions required or the short life of suitable tracersrestricts the use of certain radio-isotopes to laboratories with very specialfacilities. The chemical effects accompanying nuclear transformationshave been reviewed recently.33 Discussions have also been published ofpossible applications of stable and radio-isotopes to chemical problems.34Experimental data on a few of the more versatile radio-isotopes includethe following which have a bearing on possible applications in physicaland general chemistry :The half life of tritium, 3H, has been estimated to lie between 10.7 and12.7 years.35 Its use for evaluating (low) solubilities of water in organicsolvents has been discussed.36The half lifeof 1% has been estimated by various authors to lie in the range 5100-7200 years ; 37 its nuclear spin appears to be zero.38 Various biochemicaland chemical problems the study of which is made possible by use of thisradio-isotope have been reviewed.39 Methods of preparing barium carbonatewith high specific activity have been de~cribed.~* An interesting differencein radioactivity has been claimed between methane from sewage gas, whichgives 10.5 disintegrations/min./gC., and methane from petroleum deposits,which is inactive.41 The geochemistry of the non-radioactive isotope 13Chas also been discussed.42 Experiments on the formation of llC continueto be reported.43Much work continues on the radio-isotopes of carbon.The diffusion of 24Na into glass has been investigated.4435S has been used in the measurement of transfer constants45 and theincorporation of radio-sulphur in benzylpenicillin has been de~cribed.~~33 Ann.Reports, 1948, 45, 1 ; cf. Symposium on Radiation Chemistry, J . Phys.Colloid Chem., 1948, 52, 437.34 J. W. T. Spinks, Proc. Conf. Nuclear Chem. May, 1947, Chem. Inst. Canada, p. 134(radio-isotopes); M. Lounsbury, ibid., p. 153 (stable isotopes); 0. Holm, Angew.Chem., 1947, 59, A, 2; 0.Erbacher, ibid., p. 6.36 M. Goldblatt, E. S. Robinson, and R. W. Spence, Physical Rev., 1947, 72, 973.A. Novick, ibid., p. 972.36 G. G. Joris and H. S. Taylor, J . Chem. Physics, 1948, 16, 45.87 L. D. Norris and M. G. Inghram, Physical Rev., 1948, 73, 351 ; R. C. Hawkings,R. F. Hunter, W. B. Mann, and W. R. Stevens, ibid., p. 696; L. Yaffe and J. M.Grunlund, ibid., p. 696.38 F. A. Jenkins, ibid., p. 639.3B W. W. Miller and T. D. Price, Nucleonics, 1947, 1, 11 ; 0. Beeck, J. W. Otvos,D. P. Stevenson, and C. D. Wagner, J . Chem. Physics, 1948,16, 255.40 L. D. Norris and A. H. Snell, Physical Rev., 1948, 73, 254.41 E. C. Anderson, W. F. Libby, S. Weinhouse, A. F. Reid, A. D. Kirshenbaum, I4a G. E. Hutchinson, Amer. J . Sci., 1949, 247, 27.43 E.M. McMillan and H. F. York, Physical Rev., 1948, 73, 262; W. Heckro44 J. R. Johnson, J . Appl. Physics, 1949,20, 129.46 C. Walling, J . Amer. Chem. SOC., 1948, 70, 2361.I* Y. Sato, G. I'. Barry, and L. C. Craig, J . Biol. Chem., 1948,174, 217.A. V. Grosse, ibid., 1947, 72, 931.and P. Wolff, ibid., pp. 264, 265; E. M. McMillan and R. D. Miller, ibid., p. 80.tUBBELOHDE : ISOTOPE CHEMISTRY. 11The use of radioactive phosphorus in biochemical research introduces someunexpected diffi~ulties.~'Radioactive argon 4* and arsine 49 have been used in adsorption measure-ments.Measurements of self-diffusion in solids were amongst the first applicationsof tracer technique, but the solid isotopes of natural radio-elements wereonly of comparatively restricted interest. Self-diffusion measurementswith isotopes newly available promise to be of major importance in metal-lurgical research.Experiments with radio-isotopes of transition metalshave shown an unexpected result with 01- and y-iron. Self-diffusion ina-iron which is stable below 910" is 100 times as fast as in the y-metal whichis stable above the transition point, when both are extrapolated to 910".The diffusion coefficients are Da.Fe = 34,000 exp (-77,20O/RT) and D,+ =0.00104 exp ( -48,000/RT).51 Exchange reactions between complex ionsof Fe have been investigated using 59Fe and 56Fe.52 The exchange betweenradio-active Mn" in solution and manganese dioxide has been studied.53Radio-copper has been used in studying various exchange processes 54between copper or copper amalgam and cupric ions in solution.Theapplication of radio-tracers to friction studies has been discussed. Radio-bromine and radio-iodine have been used in measuring the velocitycoefficients of exchange reactions.55 Ethyl iodide has been used tocompare weak neutron fluxes by an estimation of the radioactive iodineproduced. 562. A number of fundamental investigations have been made with stableisotopes on the influence of mass on physical properties, especially thoseinvolving kinetic and thermodynamic differences. Some general aspectsof the differences which arise in physico-chemical properties with isotopeshave been re~iewed.~'In the gaseous and liquid states, tests on differences between the knownproperties of hydrogen compounds and deuterium compounds includemeasurements of the activity of dissolved cadmium iodide 58 in dideuteriumoxide, the kinetics of the thermal decomposition of deuterium iodide andmeasurements of the equilibrium 2DI =+ I, + D2,59 and the associationSelf-diffusion in gaseous argon has also been studied.5047 W.D. E. Thomas and D. J. D. Nicholas, Nature, 1949, 163, 719.** B. P. Burtt and J. D. Kurbatov, J . Amer. Chem. Xoc., 1948, 70, 2278.4e J. W. Hickey and E. 0. Wiig, ibid., p. 1574.61 G. E. Birchenall and R. F. Mehl, J . AppE. Physics, 1948, 19, 217.64 R. C . Thompson, J . Amer. Chem. Soc., 1948, 70, 1045.6s B. Pullman and M. Haissinsky, J . P h p . Radium, 1947, 8, 36.64 M. Quintin, P. Sue, and M. Bizouard, Compt.rend., 1948, 226, 1723; G. ICayas,65 C. C. Evans and S. Sugden, J., 1949, 270.66 P. I?. D. Shaw and C. H. Collie, ibid., p. 1217.67 H. Urey, J., 1947, 562; J. Mattauch, Angew. Chem., 1947, 59, A, 37; K.6a E. C. Noonan, J . Amer. Chem. Soc., 1949,71, 102.T. Hutchinson, PhysicaE Rev., 1947, 72, 1256.ibid., p, 2144.Schaefer, &bid., p. 42.N. F. H. Bright and R. P. Hagerty, Tram. Paraday Xoc., 1947, 43, 69712 GENERAL AND PHYSICAL CHEMISTRY.of liquid deuterium fluoride. 6o Thermodynamic properties of methylalcohol have been compared with those of methyl deuteroalcohol.61 Thesmaller molecular volume and smaller intermolecular forces of dideuteriumoxide compared with water have been investigated.62 Differences betweenthe lattice parameters in uranium trihydride, a = 6.6310 & 0.0008 A., andin uranium trideuteride, a = 6.620 If.0.002 A.63, confirm the observationswith other solid hydrides and d e ~ t e r i d e s . ~ ~In the crystalline state, isotope effects for a number of acid salts, suchas ammonium dihydrogen phosphate 65 and potassium dihydrogen arsenate,66have been measured. Transitions in the solid state below the melting pointhave been reported for deuterium chloride, bromide, and iodide. The chloridediffers in behaviour from the other two, showing only one transition whereasdeuterium bromide and iodide have twos6' A. R. U.3. BOND STRUCTURE AND BOND PROPERTIES.A large range of physical properties of molecules continues to be studiedwith the general aim of increasing the body of quantitative informationabout chemical binding.1.Amongst bond problems which continue to attract much researchmay be noted the structure of the association bonds in HF, (FHF)', and inthe corresponding deuterium compounds. The potential energy of (HF)zhas been calculated for various molecular configurations. 68 Experimentsinclude measurements of the vapour pressures of liquid hydrogen fluoride,69the dielectric polarisation of the vapo~r,~O and the Raman spectra ofpotassium hydrogen difl~oride,~l and studies on the complex salts CsF,(HF),where thermal analysis indicates the values n = 1, 2, 4, and 6.7z2. Experiments and theoretical studies on the hydrides of boron continueto be published.733. Evidence has been adduced that the tendency of boron to act asacceptor in co-ordination compounds in the series boron trifluoride, tri-6o J.H. Hildebrand and A. Gee, J. Amer. Chem. Soc., 1948,70,427.62 K. Wirtz, Angew. Chem., 1947,59, A , 138.63 R. E. Rundle, J. Amer. Chem. SOC., 1947, 69, 1719.6d A. R. Ubbelohde, PTOC. Roy. SOC., 1937, A , 159, 306.65 A. R. Ubbelohde and I. Woodward, Proc. Roy. Soc., 1942, A , 179, 399,66 D. H. W. Diekson and A. R. Ubbelohde, Actq Cryst., 1950, 3, 6.6 7 K. Clusius and G. Wolf, 2. Naturforsch., 1947, 2a, 495.68 G. E. Evans and G. Glockler, J. Chem. Physics, 1948, 16, 324.70 R. A. Oriani and C. P. Smyth, J. Amer. Chem. SOC., 1948, '70, 125.71 L. Couture and J. P. Mathieu, Compt. rend., 1949, 228, 555.72 R. V. Winsor and G. H. Cady, J.Amer. Chem. SOC., 1948, 70, 1500.L. A. K. Staveley and A. K. Gupta, Trans. Paraday Soc., 1949,45,50.Cf. S. R. de Groot andM. M. Biedermann, Physica, 1941,8, 905.See ref. 60.G. Silbiger and S. H. Bauer, ibid., p. 115; J. S. Kasper, C. M. Lucht, and D.Harker, ibid., p. 881; R. E. Rundle, ibid., 1947, 69, 2075; J. Goubeau, Angew.Chenz., 1945, 60, A , 78; cf. R. I?. Bell and H. J. Emelhius, Quart. Reviews, 1948, 2, 132.Cf. ref. 133UtBBELOHDE : BOND STRUCTURE AND BOND PROPERTIES. 13chloride, tribromide, and tri-iodide increases with increasing electro-negativity of the halogen atom, which accompanies increased electrophilicproperties of the boron atom.?* The structure and thermodynamic pro-perties of the co-ordination compound NH3,BF3 have been further in-vestigated, 75 and it has been estimated from Raman-spectrum frequenciesthat the co-ordination of nitrogen to aluminium in NH,,AlCl, lowers theN-H binding energy in this compound by 25%.764.Data on the co-ordination of iodine with molecules of various solventswith donor properties have been reviewed.77 The iodine in the brownsolutions appears to be much more reactive than that in the violet solutions.Absorption spectra 78 suggest the complex C6H6,12 in benzene solutions,which is thought to be analogous with the ion 13'.The results of spectrophotometric investigation of the interaction betweenthe ions Sb+++ and Sbffff* in solution in concentrated hydrochloric acidconcur with the evidence from the crystal Rb2SbC1, in indicating some formof bonding between the ion pair (111) and (V), which is associated withintense colour.795. In spectroscopic methods, the development of techniques 80-83for measurements on absorption spectra in the '' micro-wave " region(centimetre waves) has yielded important information on pure rotationalspectra. Molecules for which data of high precision on rotationaf-energylevels have been obtained include NH3,s** 82y 84* 85 N,0,86* 87 H20,88 ICl,s9,OCS,91 BrCN and ICN,s7~ 92 CH31,92 and CH,:CF2.93The hyperfine splitting of the energy levels of a polar diatomic molecule74 D. R. Martin, Chena. Reviews, 1948, 42, 581.7 5 A. W. Laubengayer and G. F. Cordike, J . Amer. Chem. SOC., 1948,70, 2274.76 J. Goubeau and H. Siebert, 2. anorg. Chem., 1947, 254, 126.77 J.Kleinberg and A. W. Davidson, Chem. Reviews, 1948, 42, 601 ; F. Fairbrother,7 8 K. A. Benest and J. H. Hildebrand, J . Amer. Chem. Soc., 1948,70, 2832.79 J. Whitney and N. Davidson, ibid., 1947, 69, 2076.$0 C. K. Jen, PhysicaE Rev., 1947, 72, 986.81 R. H. Hughes and E. B. Wilson, ibid., 1947, 71, 562; R. J. Watts and D.82 H. H. Nielson and D. M. Dennison, ibid., 1947, 72, 1101.S4 J. W. Simmons and W. Gordy, Physical Rev., 1948, 73, 713; D. Williams, ibid.,85 R. L. Carter and W. B. Smith, ibid., p. 1053; T. A. Pond and W. F. Cannon,8 6 D. K. Coles, E. S. Elyash, and J. G. Gorman, ibid., 1947, 72, 973.a 7 A. G. Smith, H. Ring, W. V. Smith, and W. Gordy, ibid., 1948, '43, 259, 633.S. Golden, T. Wentink, R. Hillger, and M. W.P. Strandberg, ibid., p. 92.89 R. T. Weidner, ibid., 1947, 72, 1268; 1948, 73, 254; C. H. Tomes, F. R.J . , 1948, 1051.Williams, ibid., 1948, 72, 980.W. D. Hershberger, J . Appl. Physics, 1948, 19, 411.1947, 72, 974.ibid., 1947, 72, 1121.R. S. Henderson, ibid., 1948, 73, 107.Merritt, and B. D. Wright, ibid., 1948, 73, 1334.J. Bardeen and C. H. Tomes, ibid., p. 627.91 A. Roberts, ibid., p. 1405.O2 0. R. Gilliam, H. D, Edwards, and W. Gordy, ibid., p. 635.93 A. Roberts and W. F. Edgell, J . Chem. Physics, 1949, 17, 74214 GENERAL AND PHYSICAL CHEMISTRY,in an electric field (the Stark effect) can give important information on theinteraction between nuclear spins and nuclear quadrupole moments, andthe rotational-energy le~els.80-~4* 86-94 An illustration of particular interestto chemists arises in the micro-wave spectra of methyl cyanide and iso-cyanide 95 in which the hyperfine structure of the rotational-energy levelsshows that the nuclear interaction effects are considerably larger in thecyanide.A further interesting feature is that the energy absorption bya gas in the neighbourhood of a resonance line in the micro-wave regionshifts the population of energy states in the gas from that at thermalequilibrium to a distribution where marked saturation effects have beenobserved, 8 5 9 966. Advances in the interpretation of Raman and ultra-violet absorptionspectra have made possible the study of increasingly complex problems ofmolecular constitution. A general review includes the interpretation ofstructures such as borine and he~amethyldialuminium,~~ the height of thebarrier opposing cis-trans-isomerisation in eth~lene,~s the effect of resonatingdouble bonds on electronic levels in polyatomic molecules,99 the ionisationpotential of chromophores as affected by substituents,lW the role of hyper-conjugation in near ultra-violet spectra,lOl electronic transitions in simpleunsaturated hydrocarbons,102 and steric hindrance to the planarity of dyemolecules and in cis-decalin .lo3 The ul t ra-viole t spectra of nitro- su bs titu tedorganic molecules lo4 and of anthracene compo~nds,1~~ and the ultra-violetand vacuum ultra-violet spectra of a wide variety of other organic sub-stances lo6 and of hydrogen-bridged alcohols and amides in solution havebeen systematically studied.7.Theoretical €ormuh for the absorption spectra of cyanine dyes andcarotenoids, based on simple electron models, give good agreement withexperimental values. 108 The metallic model for conjugated polyenes hasO4 W. A. Nierenberg, I. I. Rabi, and M. Slonick, Physical Rev., 1948, 73, 1430;J. Bardeen and C. H. Tomes, ibid., p. 97.H. Ring, H. Edwards, M. KessIer, and W. Gordy, ibid., 1947, 72, 1262.96 P. I. Richards and H. S. Snyder, ibid., 1948, 73, 269, 1178; R. Karplus and J.O 7 R. S. Mulliken, Ch,em. Reviews, 1947, 41, 207.O8 R. S. Mulliken and C. C. J. Rothaan, ibid., p. 219.Oe K. F. Herzfeld, ibid., p. 233.Io2 E. M. Carr, ibid., p. 293.loS L. G. Brooker, F. L. White, R. H. Sprague, S.G. Dent, and G. van Zandt, ibid.,lo* W. H. Rodebush, Chem. Reviews, 1947, 41, 317.lo6 R. N. Jones, ibid., p. 353.lo* L. W. Morrison, Id. Chem., 1947, 23, 817; L. N. Ferguson, Chem. Reviews,1948, 43, 385; E. R. Blount, M. Fields, and R. Karplus, J . Amer. Chem. Soc., 70, 194;E. R. Blount and M. Fields, ibid., p. 189 ; J. R. Platt, H. B. Klevens, and W. C. Price,J. Chem. Physics, 1949, 17, 466; C. H. Miller and H. W. Thompson, ibid., p. 845;Ta-Kong Liu and A. B. F. Duncan, ibid., p. 241.Sehwinger, ibid., p. 1020; R. Karplus, ibid., pp. 1027, 1120.loo W. C. Prince, ibid., p. 257.F. A. Matsen, W. W. Robertson, and R. L. Chuoke, ibid., p. 273.p. 325; D. H. R. Barton, J., 1948, 340.lo' G. A. Hanslow, Hsi-Teh-Hsieh, and R. C. Shea, ibid., p.426.lo8 H. Kuhn, Helv. Chim. Acta, 1948, 31, 1441; W. Kuhn, ibid., p. 1780UBBELOHDE : BOND STRUCTURE AND BOND PROPERTIES. 15also been discussed by N. S. Bayli~s.1~~ Regularities in the fluorescencespectra of a wide range of polycyclic aromatic hydrocarbons in solutionhave been described.l1°8. Much progress continues to be made in purely mathematical calcul-ations of bond structures, particularly of aromatic molecules.ll1 Thisbranch of mathematical chemistry is rapidly attaining major importance.Studies include the construction of molecular diagrams of bond length andbond character in systems such asII IIand a wide range of nitrogenous heterocyclic c0mpounds.~13 Calculationsof the electronic structure and dipole moments of pyridine 114 and electronicdiagrams for a range of conjugated nitrogenous compounds 115 have alsobeen published.A theoretical study of the oxidation-reduction potentialsof quinones has correlated these with the resonance of the x electrons.1lsThe electron distribution has been calculated in relation to the acidic andbasic strengths of indole, pyrrole, carbazole, aniline, diphenylamine, andtriphenylamine.ll7 Computations have been made on the excited electroniclevels in naphthalene, anthracene, and homologues,lls on the electronicstructure and bond lengths of coronene and pyrene,llg and on the electronicstructure of some aza-naphthalenes, -anthracenes, and -phenanthrenes.120Calculation has been made of charge diagrams for styrolene and o-, m-, andp-divinylbenzene.121 Charge distributions and bond orders have beencomputed for 4-aminostilbene and related molecules,122 and a correlation hasbeen attempted of calculated electronic structure with carcinogenic activityof the former.123 A moleoular-orbital treatment of the ultra-violet spectra ofbenzene and borazole has been p~b1ished.l~~ The electronic structure ofthiophen compounds has been compared with that of the benzene ana10gues.l~~On the basis of theoretical calculations it is claimed that several non-lo9 N.S. Bayliss, J . Chem. Physics, 1948, 16, 287.ll1 C. A. Coulson, Quart. Reviews, 1947, 1, 144.lla 0. Chalvet, L. Henriet, and E. Lesein, Compt. rend., 1947, 225, 1010.1lS M. Martin, ibid., 1948, 227, 1237.116 M. G. Evans, J. Gergely, and J.de Heer, Trans. Paraday Soc., 1949,45, 312;11' G. Berthier and B. Pullman, Compt. rend., 1945,228, 1725.11* C. A. Coulson and H. C. Longuet-Higgins, Proc. Physical SOC., 1948, 60, A , 78.lx9 W. E. Moffitt and C. A. Coulson, ibid., p. 309.120 H. C. Longuet-Higgins and C. A. Coulson, J., 1949, 971.lz1 G. Berthier and B. Pullman, Compt. rend., 1948,226, 488.lZ2 C. A. Coulson and I. Jacobs, J., 1949, 1983.123 A. Pullman, Compt. rend., 1948, 226, 486.ls4 C. C. J. Rothaan and R. S . Mulliken, J . Chem. Phy&cs, 1948,16, 118.R. Schoental and E. J. Y. Scott, J., 1949, 1683.11* J. Ploquin, ibid., 1948, 226, 245.0. Chalvet and C. Sandorfy, ibid., 1949, 228, 566.cf. M. Diatkina and J. Syrkin, Acta Physicochim. U.S.S.R., 1946, 21, 921.33, C, Longuet-Higgins, Trans.Faraday SOC., 1949, 45, 17316 GENERAL AND PHYSICAL CHEMISTRY.benzenoid aromatic hydrocarbons so far unknown should be reasonablystable once they were formed.126 An empirical equation and theoreticalcalculations have been proposed for the resonance energy of polycyclicaromatic hydrocarbons.12'9. Experimental studies on the general electronic and structural pro-perties of aromatic compounds include a variety of other techniques inaddition to those listed ab0ve.~~-l0* Bond-length variations in aromaticsystems have been reviewed; 128 the C-H bond energy in toluene and thexylenes has been estimated.lZ9 Permanent dipole moments in benzene ordioxan solutions have been reported for fused aromatic hydrocarbons suchas acenaphthene (1.6 D.) and perylene (1.9-2 D .) ; anthracene and naph-thacene have zero dipole m0rnent~s.1~0 Co-ordination in solution has beenpostulated between iodine and benzene 78 and in the coloured complexwF6*C6H6.131 Deviations from coplanarity in halogen-substituted benzeneshas been claimed, on the basis of electron diffraction experiments, for themolecules o-dichloro-, o-dibromo-, 1 : 2 : 3 : 5-tetrabromo-, hexachloro-, andhexabromo-ben~ene.~~~ The basic strengths of 14 mononitronaphthyl-amines have been measured in aqueous solution ; 3-nitro-2-naphthylamineis 10,000 times stronger than 1-nitro-2-naphthylamine, providing further /yy evidence for the substantial contribution of the Erlenmeyer formula 1\A/in the s t r ~ c t u r e . 1 ~ ~ Experimental and theoretical studies of the Mills-Nixon effect have been reviewed.134The preparation and properties of BBB-trimethylborazole have beendescribed.135 Although this compound has certain similarities withmesitylene it breaks up more easily. The reactionsCH3 of NNN- trimethylborazole indicate that the B-HB link is less stable to hydrolysis than B-Me./ \ Cryoscopic determinations of the molecular weightof free phthalocyanine and of the copper, lithium, HT SJHB-cH3 and silver derivatives in concentrated sulphuricacid give values which are in agreement with thoseH r expected for fully ionised single molecules.Theebullioscopic molecular weight of lithium phthalo -cyanine in ethyl alcohol indicates the presence of the m0n0rner.l~~126 R.D. Brovn, Trans. Faraday Xoc., p. 296; D.P. Craigand A,Maccoll, J., 1949,964.137 P. G. Carter, Trans. Faraday SOC., 1949, 45, 597.126 J. M. Robertson, Act& Cry&, 1948, 1, 101.12* M. Swarc, J . Chem. Physics, 1948, 16, 128.130 H. Lumbroso, Compt. rend., 1947, 225, 1003.131 H. F. Priest and W. C. Schumb, J . Arner. Chem. floe., 1945, '40, 2291.132 0. Bastiansen and 0. Hassel, Acta Chem. Scand., 1947, 1, 489.133 A. Bryson, Trans. Faraday Soc., 1949, 45, 257.134 H. D. Springall, G. C. Hampson, C. G. May, and H. Spedding, J., 1949, 1524.136 E. Wiberg, K. Hertwig, and A. Bolz, 2. anwg. Chem., 1948, 256, 177.136 M. V. Sirur, M. S. Muthanna, S. K, Bhattacharyya, and (Sir) J. C. Ghosh, Proc.cH3-B\ /Nat. Inst. Sci. India, 1947, 13, 141UBBELOHDE : BOND STRUCTURE AND BOND PROPERTIES.17Semi-conductor properties of phthalocyanines have been detected bymeasurements of the conductivity a t various t e r n p e r a t ~ r e s . ~ ~ ~Calculations of the molecular packing and heat of sublimation of aromatichydrocarbons 13* and measurements of the heat capacity, heat of fusion,and entropy of benzene 139 indicate normal intermolecular forces and normalthermodynamic behaviour of solid benzene.Various studies on cyclooctatetraene show that this molecule has lessresonance stability than would correspond with an aromatic resonance“pool ” of e1e~trons.l~~ Its heat of isomerisation to liquid styrene is-34-3, -+ 0-34 kcals./mole at 25”.10. The configuration and vibrational spectra of aliphatic long-chainmoleculks continue to arouse d i s c ~ s s i o n .l ~ ~ - ~ ~ ~ In problems of hydro-carbon reactivity, such as the reaction with molecular oxygen, it is not atpresent clear whether n-paraffins are mainly coiled or stretched in the vapour144 Raman spectra indicate that the dimethyl-zinc, -cadmium,and -mercury, and methylmercury halide molecules are straight andthat dimethyl disulphide has predominantly a cis-configuration of themethyl groups with considerable restriction of rotation about the S-Sbond.14611. Whereas studies on aromatic and conjugated-bond systems followmethods which have been discussed fairly extensively, for saturated mole-cules the basic electronic problems are less easily formulated with quantitativeprecision.Valuable collections of numerical data on the physical constants ofhydrocarbons include measurements of boiling point, freezing point, dp/dt,refractive index, density, viscosity, heat of vaporisation, infra-red andultra-violet absorption spectra, heat of formation, free energy andequilibrium constant of formation, entropy, and heat capacity.147 Listsof dissociation energies of carbon bonds have been c0mpi1ed.l~~ Carbon-la7 D. D, Eley, Nature, 1948, 162, 819.138 A. J. Kitaigorodski, Bull. Acad. Sci. U.X.S.R., Cl. Sci. Clzirn., 1946, 103.139 G. D. Oliver, M. Eaton, and H. M. Huffman, J. Amer. Chem. SOC., 1948, ‘SO,1502.140 E. J. Prosen, Mi. M. Johnson, and F. D. Rossini, ibid., 1947, 69, 2068; G.Berthier and B. Pullman, Trans, Faraday Soc., 1949, 45, 484; R.C. Pink and A. R.Ubbelohde, ibid., 1948, 44, 708 (where other references are given).141 J. Barrio1 and J. Chapelle, J. Phys. Radium, 1947, 8, 8 ; L. KelIner, Nature,1949, 163, 877.142 R. P. Bell, Trans. Paraday Soc., 1949, 45, 946.143 A. R. Ubbelohde, Rev. Inst. Franc. Pe‘trole Ann. Cornbust. liq*, 1949, 4,144 W. J. Taylor, J. Chern. Pliysics, 1948, 16, 257.145 F. Feher, W. Kolb, and L. Leverenz, 2. Naturforsch., 1947, 2a, 454.lp6 H. Gerding and R. Westrik, Rec. Trav. chim., 1942, 61, 412.147 “ Physical constants of hydrocarbons,” U.S. Dept. Commerce, Nat. Bur.Stand., 1949; Cf. N. Corbin, M. Alexander, and G. Egloff, J. Phys. Colloid Chem.,1948, 52, 387; H. Wiener, ibid., p. 425.448.148 J. S. Roberts and H, A. Skinner, Trans.Faraday SOC., 1949, 45, 33918 GENERAL AND PHYSICAL CHEMISTRY.halogen-bond strengths have been evaluated by a number of authors,14@and the Fox-Martin rule for the energy of carbon bonds has been reviewed.150The origins of the potential barrier hindering rotation in ethane and relatedsubstances have been investigated in terms of electrostatic interactionenergies.151 Difficulty is found in reconciling the measured entropy andspecific-heat values of 1 : 2-dichloro- and 1 : 2-dibromo-ethane with anysimple type of rotational barrier.152 Raman spectra have been used toevaluate the proportions of the different configurations assumed by moleculesthrough rotation about single bonds, i.e. the " rotational isomers " of liquidhydrocarbons 153, 154 and of dihal0genoethanes.1~5 Infra-red observationsgive similar r e ~ u 1 t s .l ~ ~ Electrostatic interactions, including quadrupoleeffects in ethane, methylamine, methyl alcohol, and dimethylacetylene,appear to account for the observed barrier to r0tation.1~~The problem of changes of reactivity in a homologous series of n-hydro-carbons continues to provoke discussion and experiment.l*2+ 143 As thenumber and distribution of C atoms changes, there are systematic trendsin molecular polarisability and other physical properties. The possibilityof coupling of the vibrations of individual bonds may affect transmissionof activation energy to a specific bond and may explain effects of structureon reactivity.143 Calculations have been made which suggest that thedecomposition of unsaturated hydrocarbons and of aliphatic free radicalstakes place a t the bond having the lowest free-valency i n d e ~ .1 ~ ~ Ionisationpotentials show a systematic decrease with increasing chain-length inparaffins and A1- and A2-olefins.159 A systematic decrease in depolarisationof scattered light with increase in chain branching of paraffin moleculeshas also been claimed.160Calculations have been made of the bond lengths of single bonds inhydrogen halides ; 161 bond dissociation energies of group I1 halides have149 A. S. Carson and H. A. Skinner, J., 1949, 936 ; H. Mackle and A. R. Ubbelohde,J., 1948, 1161. 0. H. Gellner and H. A. Skinner, J., 1949, 1145 ; A. G. Evans, " TheReactions of Organic Halides in Solution," Manchester Univ.Press, 1946; J. A.Ketelaar and G. W. van Oosterhout, Rec. Trav. chim., 1946, 65, 7.E. C. Baughan, Trans. Faraday Soc., 1948, 44, 545.151 E. N. Lassettre and L. B. Dean, J. Chem. Physics, 1948, 16, 151.15% W. D. Gwinn and K. S. Pitzer, ibid., p. 303.153 J. G. Aston, D. H. Rank, N. Sheppard, and G. J. Szasz, J. Amer. Chert%. SOG.,1948, 70, 3525.154 D. H. Rank, N. Sheppard, and G. J. Szasz, J. Chem. Physics, 1949, 17, 83;N. Sheppard and G. J. Szasz, J. Chem. Physics, 1949,17, 86, 93 ; San-ichiro Mizushimaand Hiroetsu Okazaki, J. Amer. Chem. Soc., 1949, 71, 3411.155 San-ichiro Mizushima, Yonezo Morino, Itaru Watanabe, Takehiko Simanouti,and Shigeto Yamaguehi, J. Chem. Physics, 1949, 17, 591; H. J. Bernstein, ibid.,pp.256, 258, 262.156 D. W. E. Axford and D. H. Rank, ibid., p. 430.1 5 7 E. N. Lassettre and L. B. Dean, ibid., p. 317.168 G. Berthier and B. Pullman, Corn@. rend., 1948, 226, 2146.159 R. E. Honig, J. Chem. Physics, 1945,16, 105.160 I. Fabelinsky, J. Phys. U.S.X.R., 1948, 10, 231.E. Warhurat, Trans. Paraday Soc., 1949, 45, 461UBBELOHDE : STRUCTURE AND PROPERTIES OF LIQUIDS. 19been discussed; 162 and bond lengths in some inorganic molecules havebeen reviewed and it has been pointed out that a number of bonds areunexpectedly short, as in silicon tetrafluoride, phosphorus trifluoride,M-0 in many oxy-ions and molecules, M-C in metallic carbonyls, andM-N in phtha10cyanines.l~~ The intervalency angles of 0 and S in cyclicmolecules have been re-assessed from the dipole moments.16412.Experimental techniques for investigating the mechanism of organicreactions have become progressively more rigorous from the physico-chemical standpoint, and increasing attention has been paid to quantitativedata on the various bond parameters involved. Brief mention may bemade of systematic studies where the results appear to be of a nature whichcan be correlated closely with quantitative bond structure.165 Fresh datahave also been obtained for the heats and entropies of ionisation of someorganic acids 166 in relation to their molecular structure. A. R. U.4. THE STRUCTmCE AND PROPERTIES OF LIQUIDS.1. Measurements of the surface tension and of its temperature coeficientcontinue to be made as an aid to the elucidation of the structure of liquids.A number of papers refer to the surface tension of liquid metals.Theoreticalcalculations of the surface tension of liquid argon and liquid mercuryindicate a linear temperature coefficient. 167 A general theoretical dis-cussion on the temperature coefficient of the surface tension of liquidmetals168 has been published, and a proposal has been made to evaluatethe magnitude of the surface tension of liquid metals on the basis of theSornmerfeld theory of electrons in metals.16s The temperature coefficientof surface tension has been measured for molten selenium 17* and for anumber of alicyclic hydrocarbons.171 Measurements of the surface tensionand density of lead-antimony and cadmium-antimony alloys suggest thepersistence of the compound CdSb in the liquid ~ t a t e .1 ~ ~ Restrictedmiscibility in the liquid metals AI-In and Ga-T1 contrasts with completemiscibility in the liquids Ga-Si, Ga-Ge, In-Si, In-Ge, and T1-Ge.1732. The distribution of atoms in molten Pb, TI, In, Au, Sn, Ga, Bi, andGe, and the alloy Au-Sn have been evaluated by means of Fourier analysesof X-ray diffraction spectra and have been compared with the arrangements162 H. A. Skinner, Trans. Faraday Soc., 1949, 45, 20.163 A. F. Wells, J., 1949, 55.16* K. E. Calderbank and R. J. W. Le FBvre, J., 1949, 199.166 C . K. Ingold et al., J., 1948, 812, 1283, 2038.T. L. Cottrell, G. W. Drake, D. L. Levi, K. J. Kelly, and J. H. Wolfenden, J.,1948, 1016, 1019.167 G. Jura, J . Phys.Colloid Chem., 1948, 52, 40.16* A. S. Skapski, J . Chem. Phys.ics, 1948, 16, 386, 389.16* A. Kh. Breger and A. A. Zhukhovitsky, J . Phys. Chem. U.S.S.R., 1946,20, 355.170 K. Astakhov, N. Penin, and E. Dobkina, ibid., p. 403.171 W. Hiickel and H. Harder, Chenz. Ber., 1947, 80, 357.172 H. T. Greenaway, J . Inst. Metals, 1947, 74, 133.173 W. Klernm, L. Klemm, E. Hohmann, H. Volk, E. Orlamunder, and H. A. Klein,2. anorg. Chem., 1948, 256, 23920 GENERAL AND PEYSICAL CHEMISTRY.of atoms in the corresponding solids. In melting Pb, T1, In, and Au theaverage number of nearest neighbours decreases and the average inter-atomic distance decreases ; in melting Sn, Ga, Bi, and Ge the reverse effeGtsare 0b~erved.l~~3. Applications of ultrasonic measurements to the investigation of thestructure of liquids continue to be fairly numerous.175 Observationsinclude determination of the acoustic velocity, evaluation of the temperaturecoeficient of velocity, and measurements of the absorption ~0efficients.l~~Structural influences have been investigated in a series of liquid Al-olefins(C7-15) a t 15--30°.177 In water the velocity temperature coefficientand the absorption coefficient are abnormal, ' probably owing to internalrelaxation effects 178 associated with the special structure of liquid water.Peaks in the absorption of ultrasonic vibrations are sometimes foundwhen the absorption coefficient is plotted against the composition of aliquid mixture, particularly when one of the components is water; thesemay be due to molecular association in the liquid mixture, and suggest thatdevelopments of ultrasonic techniques may build up a valuable body ofinformat ion about the structure of 1 i q ~ i d s .l ~ ~4. Ultrasonic measurements have also given interesting informationabout molecular motions in liquids composed of macro-molecules. Struc-tural influences on the value of the ratios, velocity/density, have been studiedfor various hydrocarbons -and polymers as liquids or solutions. 180 Shearwaves and longitudinal waves of ultrasonic frequencies have been studiedin polyisobutene liquid polymers with viscosity ranging from 0.3 to 1700centipoises at 25". The polymers act as Maxwellian relaxing liquids, andthe shear elastic constants increase with increasing chain length and withfalling temperature.lsl Ultrasonic measurements a t 30" and 50.7" havealso been made on a range of polydimethylsiloxanes, SiMe3*[O*SiMe2],*O*SiMes.The unusually high compressibilities found for these liquids correlate with thelow cohesive forces and low boiling point, and with large-amplitude oscillationsof the methyl groups.ls2 Hysteresis effects in viscosity determinationswith glycerol and mineral lubricating oils, when the pressure is suddenlychanged, probably arise from analogous relaxation effects in such 1 i q ~ i d s .l ~ ~174 H. Hendus, 2. h7aturforsch., 1947, 2a, 505.175 A bibliography of references (to 1939) is given by W. T. Richards, Rev. Mod.176 E. Bauer, Proc. Physical Xoc., 1949, 62, 141. J.R. Pellam and J. I(. Gab, J .177 R. T. Lagemann, ibid., 1948, 16, 247.Physics, 1939, 11, 36; cf. Repts. Progr. Physics, 1948, 11, 217.Chem. Physics, 1946, 14, 608.G. W. Willard, J . Acoust. Xoc. Amer., 1947, 19, 235; L. Hall, Physical Rev.,179 R. Parshad, J . Acoust. Soc. Amer., 1948, 20, 66; F. H. Willis, ibid., 1947, 19,18* G. Natta and M. Baccaredda, J . Polymer Sci., 1948, 3, 829.le1 W. P. Mason, W. 0. Baker, H. J. McSkimin, and J. Heiss, Physical Rev., 1948,1948, 73, 775.242; C. J. Burton, ibid., 1948, 20, 186.73, 1074.A. Weissler, J . Amer. Chem. SOC., 1949, 71, 93.lE3 F. Charron, Compt. rend., 1947, 225, 919UBBELOHDE : LIQUID AND SOLID DIPLECTRICS. 21Attempts have been made to correlate the energy of vaporisation and cohesionwith the viscosity of liquids.lM5.Systematic studies of the effect of molecular structure on the thermalconductivity of liquids give evidence for the participation of the internaldegrees of freedom in heat cond~ction.1~~ Attempts have been made tocorrelate the thermal expansion of organic liquids with their molecularstructure.ls6 The density of liquid selenium at different temperatures isof some interest in camparison with that of sulphur.lS7 A. R. U.5. THE PHYSICAL CHEMISTRY OF LIQUID AND SOLID DIELECTRICS.1. The dielectric losses of liquid chlorobenzene, bromobenzene, ethylchloride, butyl alcohol, and butyl bromide have been measured a t micro-wave frequencies (A - 3 cm.).lS8 Formuls for the internal field strengthof a dielectric show discrepancies with experiment in a number of cases.For example, the molecular polarisation Pm of a non-polar gas like carbondioxide passes through a maximum at about 250 atmospheres, and thepolarisation of ionic crystals changes when they are powdered.ls9 A newequation for the internal field strength has been claimed to be superior toOnsager’s equation.lgo The dielectric relaxation in high polymers has beencorrelated with the ability of the molecules carrying dipoles to rotate freely ; lglthe dielectric losses in rubber swollen with non-polar and with polar solventssuggest independent movement of the dip01es.l~~ Solid solutions of aliphaticlong-chain polar compounds such as ketones or esters in long-chain hydro-carbons, e.g. n-hexacosane, continue to provide important systems in whichdielectric relaxation can be correlated with detailed information about thestructure .1932.Much work continues to be published on (‘ ferro-electric ” solids such asRochelle salt, potassium dihydrogen phosphate, and barium metatitanate, inwhich the dielectric constant attains very high values below a critical tempera-ture or (‘ Curie point.’’ The term ‘( ferro-electric ’’ is used to indicate thatthe high dielectric constant is due to a co-operative effect between themolecular dipoles, which has certain analogies with the production of ferro-magnetism by co-operative effect between molecular magnetic moments.Ferro-electric domains in single crystals of Rochelle salt below the CurieILE4 L. Grunberg and A.H. Nissan, Trans. Paraday Soc., 1947,45, 125.lS6 L. Riedel, Mitt. Kaltestech. Inst., Karlsruhe, 1947, No. 2, 45 pp.le7 K. V. Astakhov, N. A. Penin, and E. I. Dobkina, J . Gen. Chem. Russia, 1947,lB8 G. E. Crouch, J . Chem. Physics, 1948, 16, 364.G. Steensholt, Phil. Mag., 1946, 37, 357.1’7, 378.E. J. Verwey, Chem. Weekblad, 1947, 43, 662; J. Icil. Bijvoet, ibid., p. 631;C. A. h i s s i n k , ibid., p. 633.loo C. J. Bottcher, ibid., p. 652.lgl W. Kiihn, Helu. Chim. Acta, 1948, 31, 1259.lg2 A. Schallamach and P. Thirion, Trans. Furaday SOC., 1949, 45, 605;lg3 R. J. Meakins, Nature, 1948, 162, 994.cf. W. C.Carter, M. Magat, W. C. Schneider, and C. P. Smyth, ibid., 1946, 42, 21322 GENERAL AND PHYSICAL CHEMISTRY.point can apparently give rise to reflexions of ultrasonic waves (10 mc./sec.).l9*The effect of the lattice constants of Rochelle salt on the electromechanicalproperties has been discussed.lg5 According to one theory, contractionof short hydrogen bonds in the crystal, due to mechanical or thermal effects,leads to a shift of the proton towards the midpoint of the hydrogen bondwith consequent changes in the polarisability.196g 197 Various studies on thecrystal domains in Rochelle salt and potassium dihydrogen phosphate havebeen p~b1ished.l~~~ lg8 Ferro-electric domains in barium metatitanate havebeen distinguished by the appearance of single crystals under the microscope,with polarised light, and by other physical properties.199 Photographs ofhysteresis loops produced on a cathode-ray oscillograph when a singlecrystal of barium metatitanate is placed in an electric field also give evidenceof ferro-electric domains.200 Methods for growing barium metatitanatecrystals have been described201 and the crystal structure has been dis-cussed.202 The properties of mixed barium-strontium titanate have alsobeen investigated .203 A. R. U.6. THE PHYSICAL CHEMISTRY OF TffE SOLID STATE.Many developments of routine crystallographic analysis are now beingpublished in the Acta Crystallogruphica.1. Though the discussion of crystallographic techniques in detail fallsoutside the scope of this section (see section 12 and the Report on Crystal-lography), mention may be made of the diffraction of neutron beams bycrystals, including sodium chloride, diamond, aluminium, sodium, sodiumbromide, sodium fluoride, sodium hydride, and sodium deuteride. It isinteresting to note that in sodium hydride the proton scatters neutronswith negative scattering amplitude, in contrast to the deuteride in whichthe deuterons scatter with positive amplitude.204 Limitations in the useof Geiger counters for the measurement of Bragg and diffuse scatteringfrom small single crystals have been disc~ssed.20~ The location of hydrogenlo* W.J. Price, Physical Rev., 1948, 73, 1132.lo6 R. M. Lichtenstein, ibid., 1947, 72, 492 ; cf. W. P. Mason, ibid., p. 976.lo6 A. R. Ubbelohde and I. Woodward, Proc. Roy. SOC., 1946, A , 185, 448.lS7 A. R. Ubbelohde, J . China. p h y e u e , 1949, 46, 429; W. P. Mason, PhysicalRev., 1947, 72, 854.lo* J.H. Thorn and If. E. Buckley, Acta Cryst., 1949, 2, 333; S. Miyake, Proc.Physico-Math. SOC., Japan, 1941, 23, Aug. and Oct. ; J . Phy8ical SOC. Japan, 1947,2,98.lo9 B. Matthias and A. Hippel, Physical Rev., 1948, 73, 268, 1378 ; cf. B. Matthias,Nature, 1948, 161, 325; H. D. Megaw, Proc. Roy. SOC., 1947, A , 189, 261 ; G. C.Danielson, Acta Crystall., 1949, 2, 90.2oo A. de Bretteville, Physical Rev., 1948, 73, 807.*01 B. Matthias, ibid., p. 809; H. F. Kay, Acta Cryst., 1948, 1, 229.H. F. Kay, If. J. Wellard, and P. Vousden, Nature, 1949, 163, 636; H. T.Evans and R. D. Burbank, J. Chem. Physics, 1948,16, 634.203 J. G. Powles, Nature, 1948, 162, 655.R. J. Finkelstein, Physical Rev., 1947, 72, 907; C. G. Schull et al,, i b a ., 1948,73, 527, 830, 842.*06 K. Lonsdale, Acta Cryst., 1948, 1, 12TTBBELOHDE: PHYSICAL CHEMISTRY OF THE SOLID STATE. 23atoms in crystals by X-ray diffraction may become possible in certainorganic compounds by the use of sufficiently precise methods for obtainingelectron-density contours in molecules.2062. Amongst new crystal structures with more than a specialised interestthe following may be noted : potassium and rubidium hydroxides,207sodium cyanate,208 the ionic layer structure in aluminium chloride,209 andthe bond-lengths in certain polysulphides.210 Preparation of non-cubic(graphitic) silicon 211 and of colourless carborundum 212 has been claimed.3. Studies of the vibration frequency and vibration amplitudes of atomsand groups in crystals continue to be published, for crystals of even greatercomplexity.The Raman spectra of crystals such as diamond, sodiumchloride, magnesium oxide, lithium fluoride, potassium chloride, caesiumchloride, aluminium oxide, ammonium chloride, calcium carbonate, andcertain metals have been recorded and interpreted theoretically in a seriesof papers. As might be expected from considerations of bond anharmo-nicity (cf. reference 19?), temperature coefficients of lattice frequencies aremuch larger than those of intramolecular frequencies in calcium carbonate.The variation of Raman spectra of ammonium chloride may be correlatedwith various transitions in the ~rystal,~13 The Debye temperature of sodiumnitride, as computed from specific heat data, is 460" & 15" K., comparedwith 505" 15" K.computed from variations of the intensity of X-rayreflections.214 Rotational vibrations have been postulated in hexamethylene-tetramine crystals to explain the change of X-ray diagrams with tem-p e r a t ~ r e . ~ ~ ~ Root-mean-square amplitudes of atomic vibrations have beentabulated for 20 elements and 24 compounds crystallising in the cubicsystem.216 Fresh theoretical calculations have been made on the zeropoint energies of lithium hydride and deuteride,217 which are evaluateda t 5.4, and 4-3, kcals. respectively.4. Crystal ion radii for tervalent and quadrivalent ions of the elementsthorium, uranium, neptunium, plutonium, and americium have beenevaluated.218 Correlation of ionic radii with solid-solution limits and withzo* J.D. Morrison, W. P. Binnie, and J. M. Robertson, Nature, 1948, 162, 889.207 T. Ernst and R. Schober, Arzgew. Chem., 1948, 60, A , 77.Zo8 hf. Bassi&, Hem. Serv. Chim. de I'Etat, 1943, 30, 30.209 J. A. Ketelaar, C. H. MacGillavry, and P. A. Renes, Rec. Trav. chim., 1947,66,501.I. M. Dawson, A. McL, Mathieson, and J. M. Robertson, J., 1948, 322.211 F. Heyd, 3'. Kohl, and A. Kochanovska, Coll. Czech. Chem. Comm., 1947,12, 502.212 R. Iley and H. L. Riley, Nature, 1947, 160, 468.213 (Sir) C. V. Raman, R. S. Krishnan, K. G. Ramanathan, and P. K. Narayaswamy,214 M. Bassidre, Mem. Sew. Chim. de Z'Etat, 1943, 30, 33.216 P. A. Shaffer, J . Amer. Chem. Soc., 1947, 69, 1557.216 K. Lonsdale, Acta Cryst., 1948, 1, 142; for other effects of temperature onX-ray scattering see E.A. Owen and R. W. Williams, Proc. Roy. Soc., 1947, A , 188,509, and G. H. Begbie, ibid., p. 189.Proc. Indian Acad. Sci., 1947, 26, A , 339.217 S. R. de Groot and M. M. Biedermann, Physica, 1941,8,905.W. H. Zachariasen, Physical Rer., 1948, '73, 110424 GENERAL AND PHYSICAL CHEMISTRY.crystal-compound formation has been made in a number of simple ioniccrystals. The solid-solution limit a t room temperature of zinc oxide in cubicmagnesium oxide is a t 33% of zinc, and that of zinc oxide in nickel oxideat 35% of zinc. Results are also given for solubilities of zinc oxide inhexagonal cadmium and cobalt m0noxides.~19 A complete range of solidsolutions is observed in the alkaline-earth carbonates barium-strontiumcarbonates and calcium-strontium carbonates, but only limited rangeswhen the differences in ionic radii are larger, as in barium-calcium carbonates(aragonite).The solid solutions rich in calcium crystallise in the aragonitestructure in the first instance, but are transformed into the calcite structureon storage.220 A predominant influence of ionic radius is apparent in thesystems formed by the salt pairsor RbCl *ac7 or KCI with MgCl, and Nal] with Mg12Thermal and X-ray analyses have indicated crystal compounds withcongruent melting points with the following formuh :Type ABX, : NaMgF,or KIKMgF3 KMgCl,RbMgF, RbMgCl,Type A2BX4 :K2MgC14Rb2MgF4 R b2MgC14and mixed crystals of sodium iodide-magnesium iodide which disintegrateat lower ternperatures.,,l Solid solutions of potassium chloride-potassiumbromide and lithium chloride-rubidium chloride have been studied.222In the system potassium nitrate-ammonium nitrate solid solution occurseven when the two salts are ground together at 40°.223 The solubility oflead dichloride in silver chloride at 270" is first decreased and then raisedby increasing amounts of dissolved cadmium5.Interstitial solid solutions have been further investigated in a numberof systems. Uranium trihydride and trideutride have been prepared ; theyare electrically conducting and have m. p. >600°, indicating a special typeof binding of the hydrogen.225 In palladium-hydrogen and cognate systemsit has been claimed that part of the hydrogen is not truly interstitial but isoccluded in rifts.226 Studies are reported on carbides MgC, and Mg2C,.227R.Rigamonti, Gazzetta, 1946, 76, 474.220 R. Faivre and G. Chaudron, Compt. rend., 1948, 226, 903.*21 W. Klemm, Angew. Chem., 1948,60, A , 57; 2. anorg. Chem., 1948,256, 25..222 J. A. Wasastjerna, Acta SOC. Sci. Penn., 1944, 3, No. 8.223 J. Whetstone, Canadian J . Res., 1948, 26, 23, 499.224 C. Wagner and K. E. Zimen, Acta Chem. Scand., 1947, 1, 539.225 R. E. Rundle, J . Amer. Chem. SOC., 1947, 69, 1719.226 D. P. Smith, Phil. Nag., 1948, 39, 477.a27 F. Irrrnann, Helv. Chim. Acta, 1948, 31, 1584UBBELOHDE : PHYSICAL CHEMISTRY OF THE SOLID STATE. 25The monocarbides (MC) of titanium, zirconium, vanadium, niobium, andtantalum are cubic, but that of tungsten and M0,C are hexagonal.Con-tinuous solid solutions are formed by metal-carbide pairs in the temperaturerange 1600-2100" as follows : Ti/V, Ti/Nb, Zr/Nb, Nb/Ta, (Ta, Nb)/V,V/Ta, Ti/Ta and probably Ti/Zr. Solubility is limited in the pairs : V/Zr ;W/Zr, V, Nb, Ta; Mo/Zr, V, Nb, Ta.,,* An electronic interpretation ofinterstitial metallic carbides, nitrides, and oxides with cubic sodiumchloride structure has been proposed, in terms of electron-deficient bondstructures in which the non-metal forms more bonds than it has orbitals.229" De-fect oxides " with stoicheiometric composition MOO, (n = 0.10 to 2-97) andwith a number of different crystal phases have been synthesised, and havebeen examined by X-rays and by electrical-resistance measurements.23oVariation of the partial pressure of oxygen over cadmium oxide at differenttemperatures gives a reversible variation of thermoelectric power, owing tothe reversible filling of lattice defects.231 Measurements of the electricalconductivities of solid oxides, zinc oxide, Fe,03, Cr203, ZnFe,04, ZnCr,O,,MgFe,O,, and MgCr,O,, have been made over a range of temperatures upto lOOO", in atmospheres of air, oxygen, hydrogen, and carbon monoxide.It has been shown that zinc oxide, Fe203, ZnFe,O,, and MgFe20, are electronconductors, whereas Cr203, MgCr20a, and ZnCr204 are positive-hole con-ductors. At temperatures between 0-5 and 0-25 Tm (T, = m.p. in OK.) theconductivity varies reversibly with oxygen pressure.The relation of theseobservations to different mechanisms of electrical conductivity in the solidsand to their chemical reactivity has been discussed.232 For SnS233 andPbS 234 the Fowler-Wilson semi-conductor theory seems insufEcient toexplain the temperature coefficients and the absolute magnitude of thethermo-electric power. X-Ray, pyknometric, and magnetochemical studiesindicate a range of defect structures in Ti(Se), and Ti(Te), (n = 2.00 tol.00).235 The conductivity and thermoelectric effect in cuprous oxide havebeen further in~estigated.,~~Periodic faults have been detected in the crystal lattices of some mole-cular complexes of 4 : 4'-dinitrodiphenyl with other diphenyl derivatives.2377. Various studies on temperature effects in crystals have been reported,which have a bearing on the thermodynamics of the solid state.Sharpanomalies in the thermal expansion and specific heat of chromium sesqui-6. Defect crystal structures continue to receive much attention.228 H. Nowotny et al., Metallf., 1947, 2, 257, 265.229 R. E. Rundle, Acta Cryst., 1948, 1, 180.Z3O 0. Glemser and G. Lutz, Angew. Chem., 1948, 60, A , 69.231 C. A. Hogarth and J. P. Andrews, PhiE. Mag., 1949, 40, 273; C. A. Hogarth,232 D. J. M. Bevan, J. P. Shelton, and J. S. Anderson, J., 1948, 1'1.29.233 J. S. Anderson and M. C. Morton, Trans. Faraday SOC., 1947, 43, 186.234 M. C. Morton, ibid., p. 194.236 P. Ehrlich, 2. angew. Chem., 1948, 60, A , 68.236 N. IN. Greenwood and J. S. Anderson, Nature, 1949, 164, 346.237 R.W. James and D. H. Saunder, Acta Cryst., 1948, 1, 81.ibid., 1948, 39, 26026 QENERAL AND PHYSICAL CREMXSTRY.oxide have been detected in the range 31-33°.238 Titanium sesquioxideexhibits anomalous thermal expansion and electrical conductivity around200".239 Specific-heat anomalies have been detected in deuterium chloride,bromide, and i0dide.6~ Nickel monoxide tends towards cubic symmetrysmoothly as the temperature rises towards 300". The fact that the latticeshows distorted cubic symmetry a t lower temperatures is attributed to theatomic-size ratio Nil0 being just too small a t room temperature for a stableface-centred cubic structure. As the temperature rises, the nickel atomsoccupy more space. Solid solutions of small quantities of iron and cobaltin nickel oxide give stable cubic structures at room temperature, apparentlybecause of the larger atomic radius of bivalent iron or cobalt comparedwith ni~ke1.~4* An important review of different types of thermal trans-formation in solids involves a classification on the basis of the thermo-dynamic treatment evolved by Ehrenfest .241 A crystallographic inter-pretation of the distinction between continuous and discontinuous thermaltransitions in solids has been proposed, on the basis that in continuoustransitions the new structure appears, not as a distinct crystal phase, butas a sub-crystalline hybrid structure in the original single crystals.242Studies of the temperature variation of the elasticity modulus of a range ofmetals from -180" to +lOOO" have been Generally themodulus falls with rising temperature, but where there are allotropicmodifications or Curie points discontinuities may arise.8.Various kinetic aspects of changes in the solid state are receivingincreasing attention from the physico-chemical standpoint. The growthof crystals has been the subject of a Faraday Society Discussion.244 Theaccommodation coefficients for vapour-solid transitions in benzene, iodine,camphor, and water are estimated to be 0.62, 0.94, 0.17, and 0.068, re-spectively, which appear to be of the same order as for the correspondingvapour-liquid transitions.245 This supports the view that the first state ofcondensed molecules on a solid surface is akin to a liquid in structure.Ithas been suggested that the surface distribution of atoms in solids is akinto the liquid state.246 Fresh evidence has been brought forward that heatinga liquid or solution above the equilibrium crystallisation temperature T,can increase the subsequent interval between T, and the temperature ofspontaneous crystallisation TT,.247 A review of reactions in the solid state238 J. Jaffray and J. Viloteau, Compt. rend., 1948, 2MY 1701.239 111. Foex and J, Loriers, ibid., p. 901.240 H. P. Rooksby, Acta Cryst., 1948, 1, 226.241 J. Jaffray, Ann. Phgsique, 1948, 3, 5 ; cf. Quart. Reviews, 1949, 3, 65.242 A. R. Ubbelohde and I. Woodward, Proc. Roy. Xoc., 1947, A , 188, 358.243 W. Koster, 2. Metallk., 1948, 39, 1.244 Faraday SOC. Discussions, 1949, 5.245 BI.K. Baranaev, J. Phys. Chem. Russia, 1946, 20, 399. Cf. J. Birks andR. S. Bradley, Proc. Roy. Xoc., 1949, A, 198, 226; R. S. Bradley and A. D. Shellard,ibid., p. 239.246 C. Gurney, Proc. Physical Soe., 1949,62, A, 642.247 R. Gopal, J . Indian Chem. Soc., 1947, 24, 279UBBELOHDL : PHYSICAL CHEMISTRY OF THE SOLID STATE. 27has been published.248 Publications on kinetic processes in the solid stateinclude evidence that dissolved water increases the rate of reaction betweenFe,O, and other oxides in the temperature range 300-700".249 Theactivation energy for diffusion of neutral coupled pairs of positive- andnegative-ion vacancies in alkali halide crystals has been calculated.25o Itis suggested that this process may be more important than the diffusionof single vacancies.251 Measurements from -40" to 120" of the specificconductance of rapidly frozen aqueous solutions of various electrolytes areinterpreted on the view that rotation of water molecules in the lattice canfacilitate transfer of H+ and OH-.252 Measurements of the internal frictionas a function of temperature and concentration of impurities in solid solutionhave been correlated with crystallographic results in the case of tantalumand z i n ~ .~ ~ 3 In solid solutions of nitrogen in iron, a new phase has beendiscovered by plotting the temperature of maximum internal friction againstcomposition.254 The transformation in the solid state for nitrito- ---+nitro-pentamminocobaltic nitrate has been investigated.2559.Some correlation of chemical reactivity or catalytic efficiency with thearrangement of atoms in various crystal faces of a solid has been achievedin a number of cases. For crystals of copper heated at 900" the rateof oxidation of the different faces is in the sequence (210), (221) > (211),(110) > (111) > (100) > 123. Measurements have also been published onthe oxidation of crystals of iron a t 850".256 Comparisons of the catalyticcombination of hydrogen with oxygen on single crystals of copper in thetemperature range 360-440" showed that at low partial pressures ofoxygen the combination rate on the crystal face (100) was twice as large ason (lll), and that the face (100) remained smooth whereas (111) wasroughened.At higher partial pressures of oxygen the activity of (111) increased.Copper powder formed rapidly on all crystal faces at mol.fractions of oxygengreater than 5%.257 In the catalytic decomposition of carbon monoxideon single crystals of nickel at 550" selective deposition of carbon was observedon the (111) faces.258 The catalytic production of (ethylene + hydrogenchloride) from ethyl chloride on crystals of barium chloride, manganouschloride, lead( 11) chloride, silver chloride, and various mixed crystals24s G. Cohn, Chem. Reviews, 1948, 42, 527.24s C. Haasser and H. Forestier, Compt. rend., 1947, 225, 240.250 G. J. Dienes, J . Chem. Physics, 1948, 16, 620.251 For refs. see Mott and Gurney, " Electronic Processes in Ionic Crystals," Oxford252 S. I. Weissmann, Nature, 1948, 161, 241.Univ. Press, 1940.Tantalum : T'ing-Sui Ke, Physical Rev., 1948, 74, 9, 16. Zinc : C.A. VVert,264 C. Zener, " Elasticity and Anelasticity of Metals," Unir. Chicago Press, 1948,a56 B. Adell and G. Tholin, Acta Chem. Scad., 1947, 1, 624.256 J. B6nard and J. Talbot, Compt. rend., 1947, 225, 411.257 H. Leidheiser and A. T. Gwathmey, J . Amer. Chem. SOC., 1948, 70, 1200.J . Appt. Physics, 1949, 20, 29.p. 120.Idem, ibid., p. 120628 GENERAL AND PHYSICAL CHEMISTRY.has been studied in relation to the dipole moment of the "activedoublet." 259The activation energy for the catalytic activity of a range of gold-cadmium alloys in the decomposition of formic acid at 225-350" has beencorrelated with the Brine11 hardness.260 A.R. U.7. ADSORPTION AND SURFACE CHEMISTRY.A great volume of work on adsorption and surface chemistry continuesto be published.1. Interest in the physical chemistry of aerosols appears to have beenstimulated by a number of wartime and agricultural applications, as wellas by the possibilities of " rain-making " by condensing droplets from airsupersaturated with m o i s t ~ r e . ~ ~ l - ~ ~ ~ Various possible nuclei for " rain-making " include sodium chloride 262 and silver iodide.263 The growth ofparticle size with time in aerosols has been discussed by various authors.2642. Measurements on the adsorption of gases on solids have been used inmany cases to calculate the available surface of the absorbent by theBrunauer-Emmett-Teller m e t h ~ d .~ ~ ~ a - f Discrepancies from these authors'adsorption theory have been n ~ t e d . ~ ~ ~ ~ , b Another main objective has beenthe evaluation of integral and differential heats of adsorption.266a-b Othersinclude the measurement of dielectric constants of vapours of ethyl chloride,butane, and ethyl ether on silica, which indicate that adsorbed ethylchloride acts as a non-polar compound owing to restricted mobility of themolecule carrying the dipole in the adsorbed layer.267 The heat capacityof nitrogen adsorbed on titanium dioxide in the temperature range 20-430" K.is slightly below that of bulk nitrogen in the gas phase.266e Phase changes259 G. A. Schwab and A. Karatras, J . Phys. Colloid Chenz., 1948, 52, 1053.260 G. A. Schwab and S.Pesmatjoglou, ibid., p. 1046.261 E. B. Kraus and P. Squires, Nature, 1947, 159, 489.262 H. Dessens, Compt. rend., 1948, 226, 506.263 B. Vonnegut, Chem. Reviews, 1949, 44, 277.264 I. S. Artemov, J . Phys. Chem. RZGSS~Q, 1947, 20, 553 (mineral oil aerosols);P. S. Prokhorov and V. N. Yashin, Colloid J . U.S.S.R., 1948, 10, 122 (water droplets).D. W. E. Axford, K. F. Sawyer, and T. M. Sugden, Proc. Roy. SOC., 1948, A, 195, 13(hygroscopic aerosols).265 ( a ) R. T. Davis and T. W. De Wtt, J . Amer. Chem. SOC., 1948, 70, 1135; (b)S. J. Gregg and J. Jacobs, Trans. Faruday SOC., 1948, 44, 574; J. F. Duncan, sibid.,1949, 45, 879; (c) P. H. Emmett, Chem. Reviews, 1948, 43, 69; ( d ) M. A. Cook, J . Amer.Chem. SOC., 1948, 70, 2925; ( e ) M. Dole, J .Chem. Physics, 1948,16, 25; (f) A. G. Foster,Faraday SOC. Discussion, 1948, 3, 41.266 ( a ) L. G. Joyner and P. H. Emmett, J . Amer. Chem. SOC., 1948, 70, 2359; (b)idem, ibid., p. 2353; (c) J. Perreu, Compt. rend., 1948, 226, 907; (d) V. A. Crawfordand F. C. Tompkins, Trans. Paraday SOC., 1948, 44, 698; ( e ) J. A. Morrison and G. J.Szasz, J . Chem. Physics, 1948, 16, 280 ; (f) C. Pierce and R. N. Smith, J . Phys. ColloidChem., 1948, 52, 1111, 1115; (9) J. Perreu, Compt. rend., 1948, 226, 492, 2138; 1949,228, 1429; ( h ) P. R. Basford, (3. Jura, and W. D. Harkins, J . Amer. Chem. SOL, 1948,'20, 1444.267 R. McIntosh, H. S. Johnson, N. Hollies, and L. McLeod, Canadian J . Res.,1947, 25, B, 566UBBELOHDE : ELECTROCHEMISTRY AND IONIC CBEMISTRY. 29have been postulated in films of vapour adsorbed on solids to explain thevariation in surface compressibility with surface pressure .268 Sorption-desorption isotherms of water vapour on silica gel indicate that the sorbedliquid does not freeze a t -5°.2693.Various aspects of the surface chemistry of liquids have been discusseda t a recent Faraday Society meeting.270 The variation of surface viscositywith surface pressure has been measured for various unimolecular layers.271The phenomena of electrocapillarity have been reviewed.272 Adsorptionfrom solutions has a most important application to the technique ofchromatographic separation of components. Most developments of thistechnique merely have applications in view, but theoretical discussionsand interpretations have been proposed by a number of authors.273A. R.U.8. ELECTROCHEMISTRY AND IONIC CHEMISTRY.Several main objectives can be recognised in publications on electro-chemistry and ionic chemistry during the period under review.1. The main interest of new investigations of ions in aqueous solutionhas concentrated on new types of molecules giving colloidal ions by theassociation of smaller molecules into a micelle 274 or because of the poly-merisation of a large number of ionising groups into a macro-molecule.2752. Studies of molten electrolytes include the determination of viscosityisotherms from 580" to 690" for mixtures of cadmium chloride and cadmiumbromide. The derived activation energy is about 1.7 times the activationenergy for ionic migration calculated from the electrical conductivity.276From observations on the electrolytes or cryolite-alumina baths it has beensuggested that the primary ionic process is the electrolysis of sodiumoxide.277 Electrode processes in molten electrolytes have been reviewedfor molten alkali sulphates, phosphates, carbonates, silicates, fluorides, andwith special reference to the oxygen over-potential a t a smoothplatinum anode.The electrical conductivity has been measured for silicatemelts containing calcium, manganese, and aluminium.279268 S. J. Gregg and F. A. P. Maggs, Trans Faraday SOC., 1948, 44, 123.269 W. 0. Milligan and H. H. Rachford, J. Amer. Chem. SOC., 1948, 70, 2922.270 Faraday SOC. Discussions, 1948, 3.271 M.Joly, J. Chim. physique, 1947, 44, 206, 213.272 D. C. Graham, Chem. Reviews, 1947, 41, 441.273 Chromatographic Adsorption, Faraday SOC. Discussions, 1949, in the press.274 (Only a selection of papers on micelle formation is given; cf. An?&. Reports,1948, 45, 33.) (a) G. L. Brown, P. F. Grieger, A. C. Kraus, and H. S. Young, J. Airier.Chem. SOC., 1949, 71, 95, 309; (b) W. D. Harkins, J . Chem. Physics, 1948, 16, 156;R. W. Mattoon, R. S. Stearns, and W. D. Harkins, ibid., p. 644.275 R. M. Fuoss and U. P. Strauss, J. Polymer Sci., 1948, 3, 246, 602, 603.276 H. Bloom, B. S . Harrap, and E. Heymann, Proc. Roy. SOC., 1948, A, 194, 237.277 R. Gadeau, Bull. SOC. frang. &ect., 1947, 7, 640.278 H. Flood and T. Ferland, Faraday Xoc. D ~ S G U S S ~ O ~ S , 1947, 1, 302,279 J.O'M. Bockris, J. A. Kitchener, S. Ignatowicz, and J. W. Tomlinson, ParadaySOC. Discussions, 1948, 4, 26530 GENERAL AND PHYSICAL CHEMISTRY.3. Studies on ionic processes in non-aqueous systems have a numberof features of general interest. These include the study of ionic reactionsin liquid hydrogen cyanide.280 Conductance measurements have beenmade on various salts dissolved in nitrobenzene,281 including the mixedsalt system NaCI-A12Br,-C6H,*W02.282 Although acetic anhydride is itselfpractically non-conducting, conducting solutions are obtained with a widevariety of salts, which include arsenic trichloride and antimony trichloride,with or without added potassium chloride, zinc chloride, bismuth chloride,cobaltous iodide, triphenylmethyl chloride, or tetramethylammoniumIn liquid sulphur dioxide a maximum in the conductance isfound when equimolecular proportions of an acid chloride and aluminiumchloride or antimony pentachloride are present.Apparently new types ofcation are formed.284 Proposed equations areCH,*COCI + SbC1, ---+ CH,*CO+ + SbC1,-NOCl + AICI, --+ NOf + AIC1,-The ionisation of triphenylmethyl bromide by the additions of stannicbromideCPh,Br + SnBrdhas been measured in benzene, chlorobenzene, bromobenzene, ethylenedibromide, and ethyl bromide.285 Liquid dinitrogen tetroxide has beenstudied as an ionising solvent.286 In ethyl ether the E.M.F. of cells of thetypePh,C* + SnBr,-Ag,AgBrlLiBr in Et,O/LiBr in Et,OlAgBr,AgC1 c2has been measured, with the addition of lithium perchlorate to fix activityfactors .287 Velocity coefficients have been determined for exchangereactions between lithium bromide and alkyl bromides in anhydrous acetonesolution.288 These indicate incomplete dissociation of lithium bromide.Incomplete dissociation of hydroxides of sodium, potassium, rubidium,calcium, barium, and thallium in aqueous solution has been measured byreaction-kinetic methods.289 Acid-catalysed alcoholysis in toluene and ina number of polar solvents has been studied.290 The structure of nitricacid has been studied in solvents such as chloroform and ether,291 and theS8O G.Jander and B. Gruttner, Chem. Ber., 1948, 81, 102, 114.281 E. G. Taylor and C. A. Kraus, J . Amer, Chem. Soc., 1947, 69, 1731.s8P I.S. Bigich, J. Qen. Chem. Russia, 1946,16, 1783.288 H. Schmidt, I. Vry’ittkop, and G. Jander, 2. anorg. Chesn., 1948, 256, 113.%a4 F. See1 and H. Bauer, 2. Naturforsch., 1947, 2b, 397286 C. C. Addison and R. Thompson, J., 1949, S1, 211.287 U. Berglund and L. G. Sillen, Acta Chem. Scad., 1948, 2, 116.F. Fairbrother and B. Wright, J., 1949, 1058.C. C. Evans and S. Sugden, J . , 1949, 270.R. P. Bell and J. E. Prue, ibid., p. 362.%SO M. F. Carroll, ibid., p. 2188.sD1 R. Dalmon, Mem. Serv. Chim. de l’gtat, 1943, 30, 141UBBELOHDE : KINETIC STUDIES. 31dissociation of hydrogen chloride has been studied in alcohol, acetone, anddioxan by optical methods.2924. Much interest has continued to be shown in the properties of solutionsof alkali metals and alkaline earths in liquid ammonia.The molar volumeof sodium in liquid ammonia has been evaluated.293 Measurements onsodium-ammonia at low temperatures 294 give no evidence for super-conductivity or anomalous magnetic properties. Phase diagrams ofpotassium, lithium, calcium, strontium, barium, and calcium in liquidammonia have been investigated in relation to the electrical conductivity,magnetic susceptibility, and dielectric constants of the systems 295 (cf.section 11).The polarography of solutions of alkali metals and of tetraethyl-,tetrapropyl-, and tetrabutyl-ammonium iodide in liquid ammonia hasbeen studied. The results are interpreted in terms of a cathodic dissolutionof electr0ns.~~65. Ionic processes at electrodes, especially the phenomena of over-voltage, have been discussed by various authors a t a Faraday Societymeeting.297 The standard electrode potentials of the elements have beenreviewed .297a A.R. U.9. KINETIC STUDIES. PHOTO-REACTIONS AND AUTOXIDATION.Of the publications in these two special sections of kinetic studies, anumber of general interest may be referred to.1. The photochemical oxidation of cyclohexene, 1 -methylcyclohexene,2 : 6-dimethylocta-2 : 6-diene, and ethyl linoleate has been studied. Theprimary act is postulated to be the dissociation of the 0-0 bond in theperoxide ROOH. All four oxidations have thermal activation energiesranging from 6 to 8 k ~ a l s . ~ ~ ~ The photochemistry of aldehydes298a andketones 299 has been reviewed.Photo-sensitisation reactions includestudies of the role of metal vapours such as zinc, cadmium, and mercury ingas reactions.300 Photo-sensitisation of reactions by fluorine and chlorine,and probably by bromine, is attributed to the formation of atoms.301Photo-formation of atoms from hydrogen chloride is also assumed to explain292 E. A. Braude and E. S. Stern, J., 1948, 1971, 1976.293 A. J. Stosick and E. B. Hunt, J. Amer. Chem. SOC., 1948, 70, 2826.2g4 L. Giulotto and A. Gigli, Physical Rev., 1947, 71, 211 ; A. J. Birch and D. IC. C.295 A. J. Birch and D. K. C. MacDonald, ibid., 1948, 44, 735.2B6 H. A. Laitinon and C. J. Nyman, J . Amer. Chem. SOC., 1948,70,2241, 3002.297 Faraday Xoc. Discussions, 1947, 1.297u J. O’M. Bockris and J.F. Herringshaw, Faraday SOC. Discztssions, 1947, 1, 328.2B8 L. Bateman and G. Gee, Proc. Roy. SOC., 1948, A, 195, 376.29*u F. A. Blacet, J. P h p . Colloid Chem., 1948, 52, 534.29Q W. A. Noyes, ibid., p. 546.sOO E. UT. R. Steacie, Canadian J. Res., 1948,28, B, 609.301 J. W. T. Spinks, Canadian. J . Res,, 1948,26, B, 629.MacDonald, Trans. Paraday SOC., 1947, 43, 792.L. B. Thomas and W. D.Gwinn, J. Amer. Chem. Soc., 1948, 70, 264332 GENERAL AND PHYSICAL CHEMISTRY.the vapour-phase addition of hydrogen chloride to ethylene initiated byultra-violet light .302 The photolysis of dimethylmercury in the presenceof hydrogen to produce methyl radicals has been re-in~estigated.~~~2. A number of photo-reactions involving more complex molecules,such as fluorescent dyes and chlorophyll, have been interpreted wit~h theaid of the " exciton " hypothesis.304 Investigations of the photo-voltaiceffect a t electrodes of zinc, cadmium, and silver have exhibited the profoundinfluence of dissolved oxygen.305One typical proposed structure is :3.Investigations continue on oxygen-carryingCH,---C€€, I N=CH I HC==NInitiation of oxidations by atomic hydrogen has beenThe autoxidation of tetralin 308 and of olefins 309 has been further studiedcobalt compounds.306further in~estigated.~~'in terms of the peroxide radicals taking part in the reaction mechanism.Hydrogen peroxide has been isolated as calcium peroxide octahydrate fromthe oxidation products of pr0pane.~1~ Reference may be made to threerecent symposia on hydrocarbon oxidation,311 and to various papers onthe oxidation of hydrocarbons and related molecules in the gas phase.312Studies of the emission spectra from flames a t low pressures have giveninteresting information about effective rotational and translational tem-peratures of the molecules.313 A.R. U.10. THE PHYSICAL CHEMISTRY OF MACRO-MOLECULES.1. In connection with statistical studies on rubber-like molecules, newexperimental tests and theoretical discussions have been published on the302 J. H. Raley, F. F. Rust, and W. E. Vaughan, J. Amer. Chem. SOC., 1948, 'SO, 2767.303 M. K. Phibbs and B. de B. Darwent, Trans. Faraday Soc., 1949, 45, 541.304 G. 0. Schenk, Naturwiss., 1948, 35, 28; R. Livingston, J. Phys. Colloid Chem.,1948, 52, 527; R.Livingston and R. Pariser, J. Amer. Chem. Soc., 1948, 70, 1510;T. Forster, 2. Naturforsch., 1947, 2&, 174.305 J. M, Blocher and A. B. Garrett, J. Amcr. Chem. Soc., 1947, 69, 1594.306 H. Diehl et al., Iowa State Coll. J . Sci., 1947, 21, 271, 278, 287, 311, 316, 326.307 E. J. Badin, J. Amer. Chem. Soc., 1948, 70, 3651, 3965.308 A. Robertson and W. A. Waters, J., 1948, 1574, 1578, 1585.309 L. Bateman and G. Gee, Proc. Roy, Soc., 1948, A , 195, 391.310 P. L. Kooijman, Rec. Trav. chim., 1947, 66, 217.311 Faraday SOC. Discussions, 1947, 2; cf. Rev. Inst. Frang. Pe'trole Ann. Combust.liq., 1949, 4; Third Symposium on Combustion Flame and Explosion Phenomena,Williams and Wilkins Go., Baltimore, 1949.312 M. F. R. Mulcahy, Trans.Farday Soc., 1949, 45, 537, 575; G. A. McDowelland J. 33. Thomas, J., 1949, 2208, 2217; (Sir) A. Egerton, E. J. Harris, and G. H. S.Young, Trans. Faraday Soc., 1948, 44, 745.313 A. G. Gaydon and H. G. Wolfhard, Proc. Roy. Soc., 1948, A , 194, 169; 1949,199, 89UBBELOHDE : THE PHYSICAL CHEMISTRY 03 MAORO-MOLECULES. 33structure and thermodynamic functions of rubber, “ Polythene,” andrubber-liquid Acoustic determinations of the physical constantsof rubber-like materials have given data on the velocity of sound, and theattenuation coefficient from which Young’s modulus and the associatedviscosity coefficient have been calculated.315 The thermo-elastic behaviourof certain plant tissues has been ~ t u d i e d . ~ f ~2. Various physico-chemical studies on the sorption of water by proteinshave been published.Differential and integral free energy, entropy, andheat changes have been evaluated for the sorption of water by silk, wool,ovalbumin, collagen, gelatin, and lactoglobulin. The differential entropychange, a t low vapour pressures, suggests that the initial stages of sorptionof water may be accompanied by re-arrangement of protein chains.317Measurements of the dielectric constant of keratin show that, as the amountof water absorbed increases, the dielectric constant increases, probablybecause of an increased freedom of rotation of polar groups in the macro-m0lecule.3~~ Results have also been published for the effects of sorptionof n-propanol and acetone.319 Desorption isotherms have been publishedfor the removal of water from benzoylated casein.320Thermodynamic measurements of the binding of copper by bovineserum albumin 321 and on the combination o f Orange-I1 acid with woolkeratin322 have been interpreted in terms of the molecular structures ofthe protein.X-Ray studies of single crystals of tomato bushy-stunt virusgive further insight into the effects of partial removal of water from acrystalline protein, which leads to a slight disorientation of the internalcrystalline regions.323 The attractions, a t distances of several thousand A.,between macro-molecules in liquids have been further ons side red.^^ Adiscussion on lipoproteins was held in August, 1949, by the Paraday Society.Energy transport in proteins has been associated with the giant networkof hydrogen bonds.3253.Miscellaneous studies of the physico-chemical properties of macro-molecules include measurements of the infra-red spectra of the silicones.32sA. R. U.314 D. G. Fisher, Proc. Physical SOC., 1948, 60, 99; G. Gee, Trans. Faraday SOC.,1946, 42, B, 33; J . Chim. physique, 1947, 44, 66; R. Kubo, J . Colloid Sci., 1947,2, 527; H. Kuhn, ReZv. Chim. Acta, 1948, 31, 1677; W. Parks and R. B. Richards,Trans. Faraday Soc., 1949, 45, 203.316 A. W. Nolle, J . Acoust. SOC. Amer., 1947, 19, 194.316 0. Treitel, J . Coll, Sci., 1947, 2, 453.317 S. Davis and A. D. McLaren, J . Polymer Sci., 1948, 3, 16.318 G. King, Trans. Faraday Soc., 1947, 43, 601.320 E. F. Mellon, A. H. Korn, and S.R. Hoover, J . Amer. Chern. SOC., 1948, ‘SO, 1144.811 I. M. Klotz and H. G. Curme, J . Amer. Chern. Soc., 1948, 70, 939.322 A. B. Meggy, Trans. Faraday SOC., 1947, 43, 502.823 C. H. Carlisle and K. Dornberger, Ackc Cryst., 1948, 1, 194; cf. (Turnip Yellow324 J. Winter, Compt. rend., 1948, 226, 704.326 K. Wirtz, 2. Natur-wsch., 1947, 2b, 94.826 R. E. Richards and H. W. Thompson, J., 1949, 124.31s Idem, ibid., p. 552.Mosaic Virus), J. D. Bernal and C. H. Carlisle, Nature, 1948, 162, 139.REP.-VOL. XLVI. 34 GENERAL AND PHYSICAL CHEMISTRY.11. MAQNETOCHEMISTRY.1. Magnetochemical Aspects of Cata&is.-It has long been thoughtthat some relation may exist between catalytic activity and the phenomenonof paramagnetism. Obvious parallelisms exist between the pronouncedmagnetic properties of the transition-group metals and their catalyticeffects, the non-uniform fields in the neighbourhood of paramagnetic centreshaving been invoked by several workers as one of the main causes of generalcatalytic It is not wholly decided whether paramagnetismaccompanies catalytic activity, merely because the free valencies which areeffective for catalysis involve paramagnetic orbita.ls, or whether intenselocal magnetic fields have a catalytic effect by lifting the quantum restrictionson certain changes of bonding.The examples which follow illustrateboth possibilities.(a) The ortho-para-Hydrogen Conversion.-The discovery of the catalyticortho-para-hydrogen conversion presented the first clear example of thelifting of quantum restrictions by intense magnetic fields.Early work 328showed that, at low temperatures, conversion was much more rapid oncatalysts exhibiting paramagnetism. such as chromium sesquioxide andgadolinium oxide. Weakly paramagnetic oxides such as cerium dioxide,and diamagnetic oxides, were relatively ineffective. The conversion involvesisolated molecules and is effected by the non-uniform magnetic forces in theneighbourhood of the paramagnetic ions.328 At higher temperatures, e.g., onmetal wires, magnetic forces need not be inv0ked.~30 ortho-para-Conversionis thought to proceed by an exchange of atoms between a hydrogen moleculein an absorbed monolayer and a hydrogen atom in the underlying stablechemisorbed layer. Experiments by Burstein 331 indicate that this exchangemechanism may be the main route on charcoal even a t 80” K., contrary to theview 332 that in this case (‘ surface paramagnetism ” is the responsible factor.The observed inability of NN-diphenyl-N‘-picrylhydrazyl to catalyse theortho-para-conversion 333 in spite of its undoubted paramagnetism appearsto be due to its non-adsorptive properties, which prevent intimate contact ofhydrogen with the region of intense non-uniform magnetic field.Whenintimately mixed with a suitable adsorbent such as zinc oxide this free radicalhas strong catalytic activity.( b ) Mixed Oxides and Solid Solutions.-Evidence for the existence of arelation between catalytic activity and magnetism has been obtained by327 R.Kuhn, in Freudenberg’s “ Stereochemie,” F. Deuticke, Leipzig, 1933,p. 917 ; cf. P, W. Selwood, Chem. Reviews, 1946, 38, 52, 55, for other refs.328 H. S. Taylor and H. Diamond, J. Amer. Chem. Soc., 1933, 55, 2613.32* A. Farkas, “ Light and Heavy Hydrogen,” Cambridge Univ. Press, 1935,530 J. K. Roberts, Proc. Roy. SOC., 1935, 152, 445; D. D. Eley, ibid., 1941, 178,331 R. Burstein, Acta Physicochim. U.S.S.R., 1938, 8, 857.332 P. W. Selwood, Chem. Reviews, 1946, 38, 51.333 J. Turkevich and P. W. Selwood, J . Amer. Chem. Soc., 1941, 83, 1077.p. 95.452; Trans. Paraday Soc., 1948, 44, 216PINK : MACINETOCHEMISTBY. 35G. F. Huttig and his co-workers from studies on mixed 0xides.3~~ Oneexample is provided by mixtures of zinc oxide and chromium sesquioxide.These show striking changes in catalytic activity when heated, which areclosely paralleled by changes in the magnetic susceptibility of the mixtures.For the equimolecular mixture the activity for the thermal decompositionof methanol reached a sharp maximum a t 400°, a steep rise in susceptibilitywith incipient ferromagnetism being observed a t approximately this tem-perature.Above 400" a decrease in activity with a simultaneous loss offerromagnetism occurred. In explanation, the formation of intermediatecompounds is suggested, but their exact nature is not certain and thequestion must remain open.332V. Cirilli335 has studied the magnetic behaviour of a number of solidsolutions of metallic oxides. The susceptibility x for alumina-ferric oxidesystems treated a t 600" and 850" showed a striking increase with increased[Fe,O,] owing to the presence of strongly magnetic y-Fe203 held in solidsolution by y-A1203.For any proportion of ferric oxide in excess o f 67%,x drops considerably owing to formation of the weakly magnetic rhombo-hedral form corresponding to cc-Fe,O,. Only small paramagnetic sus-ceptibilities were observed in the system chromium sesquioxide-aluminairrespective of chromium content and temperature of heating.Mixed oxides in the form of '' supported " catalysts have been studiedextensively by P. W. Selwood and his c o - w ~ r k e r s . ~ ~ ~ Measurements of x a tdifferent temperatures for catalysts comprising chromium sesquioxide ony-Al,03 and molybdenum dioxide on y-A120, showed that the magneticproperties of the catalyst approached those of a magnetically dilute com-pound; i.e., one in which interaction between the magnetic centres is at a,minimum.With increasing [Cr3+] an increase in the Weiss constant wasobserved. There is evidence that the surface in these catalysts is onlypartly covered by a chromium sesquioxide layer.The Weiss constant for manganese oxide catalysts supported on aluminashows a striking variation with concentration, reaching a sharp maximuma t -8% of manganese. It is suggested that the crystal lattice of aluminaexerts an inductive effect on manganese oxides which tend to conformto the lattice structure of the support even to the extent of a changeof valency. The presence of MnlI1 a t low, and %Iv at high, concentrationswas confirmed by analysis.Support for this hypothesis was obtainedby demonstrating that manganese oxides supported on rutile, which isisomorphous with manganese dioxide, exhibit no anomalies of the kinddescribed.(c) Adsorbed Substances and Catalytic Poisons.--The magnetic propertiesof adsorbed substances frequently exhibit anomalies. Pioneer work ins34 G. F. Huttig, KolEoi&-Z., 1942, 99, 262; 1942, 98, 263; 1941, 97, 281; 1941,94, 137, 258; for other refs. see Selwood, ref. 332.535 V. Cirilli, Qazzettu, 1947, '77, 255.ss6 P. W. Selwood et d., J . Anzev. Chern. SOC., 1946, 68, 2055; 1947, 69, 1590;1948, 70, 2145, 2271 ; 1949,71, 693,252236 GENERAL AND PHYSICAL CHEMISTRY.this field is due to S.S. Bhatnagar, K. N. Mathur, and P. L. K a p ~ r , ~ ~ ’ whoshowed that the salts of many transition-group metals become diamagneticafter adsorption on charcoal.338 This change in magnetic susceptibilityprovides strong evidence for the formation of complexes on the surface ofthe charcoal, in which the unpaired electrons responsible for the para-magnetism of the ion take part in covalent binding with the substrate.Recent work 339 throws light on these ‘‘ chemisorptive bonds.’’ Sus-ceptibility measurements by the Sucksmith method on a palladium catalyston which dimethyl sulphide had been adsorbed revealed a significantdecrease in the paramagnetism of the catalyst. Alkyl sulphides are powerfulpoisons for palladium and are strongly adsorbed. It is inferred that thebinding involved in this adsorption is of a type in which electrons from thed-band of the palladium take part.The authors compare this effect withthe effect of hydrogen atoms on the d-band of the metal in palladium-hydrogen systems. In previous work, E. B. Maxted and R. MT. D. Morrish 340had shown that poisoning by compounds containing sulphur or phosphorusdepended on the presence, in the valency shell of the toxic element, of freeelectron pairs, Thus, organic sulphides and thiols are toxic, whereas thecorresponding sulphones and sulphonic acids are not.R*C :;: H .. Toxic : ROC :g: OR’ . *0 00 0ROC :*i OH .. ROC : K: C*R‘ .. Non-toxic :On the basis of the magnetic evidence it is suggested that a chemisorbedmolecule transfers an electron to a vacant surface d-orbital, the para-magnetic susceptibility of the surface palladium atoms being therebyreduced to zero.A survey of other work341 also showed that the only metal ions whichare toxic to hydrogenation catalysts such as platinum are those in whichthe d-orbitals of the toxic ion are occupied by either electron pairs or singleelectrons.If unoccupied d-orbitals are present or if no d-orbitals arepossible, toxicity is not observed. The possibility that the binding in thecase of the adsorbed metallic ions involves electrons excited into the un-occupied s- and p-orbitals appears to be precluded by further observations.Strong toxic action towards a platinum catalyst was observed with dimethyl-mercury, trimethylindium, and tetrameth~l-lead.~~~ With the lead compound337 S.S. Bhatnagar, K. N. Mathur, and P. L. Kapur, lndiun J . Physics, 1928, 3,338 Cf. A. Boutaric and P. Berthier, J . Chim. physique, 1942, 39, 129; Chem. Zentr.,s3e M. H. Dilke, D. D. Eley, and E. B. Maxted, Nature, 1948, 161, 804; cf. E. B.340 E. B. Maxted and R. W. D. Morrish, J., 1940, 252.s41 E. B. Maxted and A. Marsden, ibid., p. 469.342 E. B. Maxted and K. L. Moon, J., 1949, 2171.53.1943, I, 1456.Maxted, J., 1949, 1987PINK : MAGNETOCHEMISTRY. 37all four of the s- and p-orbitals are engaged in covalent-bond formationwith carbon (if the usual structure for these compounds is accepted).Excitation of electrons into these levels cannot, therefore, be a necessityfor chemisorptive binding.Reduction to the metal on the catalyst surfaceof the ions themselves or of the metallo-organic compounds seems to beexcluded. Metallic salts which are poisonous for catalytic hydrogenationsare also toxic for oxidation and reduction of the metallo-organiccompounds does not occur to a significant extent under the experimentalconditions.344 The close connection between catalytic activity and magneticsusceptibility for the metallic ions is shown in the following table. Catalyticactivity rises to a maximum with palladium and platinum, the two metalswith maximum x, and falls to a low or even zero activity with the diamagneticmetals, silver and gold.Metal Ru Rh Pd Ag 0 s Tr Pt AuAtomicno. (44) (45) (46) (47) (76) (77) (78) (79)The views expressed by Maxted and his co-workers are interconnectedwith earlier experiments by G.-IM.Schwab and his who obtainedaccurate measurements of the activation energy for formic acid dehydro-genation by catalysts consisting of alloys of silver, gold, or copper with awide range of other metals. A general relation was claimed between theactivation energy for this reaction and the degree of completion in anyparticular alloy of the first Brillouin zone, the activation energy increasingwith the degree of electron saturation of the zone. This led directly to theconcept that catalytic activation consists in a transition of electrons fromthe substrate to the metallic catalyst. As might be expected on this view,a sharp maximum in activation energy was observed for y-phases, in parallelwith the striking minimum in their electrical conductivity.A magneticstudy of the alloys used by Schwab might well prove of great interest inthis connection.The magnetic properties of oxygen adsorbed on charcoal continue toattract interest. It now seems well established that the adsorbed gas hasthe same susceptibility a t room temperature as gaseous oxygen. Variousauthors346 observed a slow diminution with time of the paramagnetism ofthe charcoal-oxygen system as a result of carbon dioxide formation. Theirwork has been confirmed by C . Courty347 who found a steady decrease inx during almost a year. According to Courty the first stage in carbondioxide formation is the production of oxygen atoms on the charcoal surface.Xg.-at.+51*8 +114*2 $476.2 -21.6 $9.5 +29*0 +214*7 -29.6343 E. B. Maxted, J . , 1922, 1760.344 V. N. Ipatiew, G. Rasurvajew, and I. F. Bogdanow, Ber., 1930, 63, 335.345 G.-M. Schwab et al., Trans. Faraduy Xoc., 1946, 42, 689; Ber., 1943, 76, 1228;Naturwiss., 1943, 31, 27, 345; 2, anorg. Chem., 1944, 252, 205; 2. Elektrochem., 1944,50, 204.346 J. Aharoni and F. Simon, 2. physikal. Chem., 1929, B, 4, 175; R. Juza andR. Langheim, Nuturwiss., 1937,25, 522 ; R. Juza, R. Langheim, and H. Hahn, Angew.Chem., 1938, 51, 354; R. Juza and R. Langheim, 2. Elektrochem., 1939, 45, 689.347 C. Courty, Colioque sur l'adsorption, Centre Nat. Recherche Scient., Paris, 194938 GENERAL AND PHYSICAL CHEMISTRY.9. Structural Problems in Organic C?hemistry.-(a) Structure and driagneticSwceptibility of Organic Compounds.-Applications of the magneticmethod t o structural problems continue to attract interest.Molecularcompounds of s-trinitrobenzene with hydrocarbons and phenols have beenexamined.348 In each case the molecular compound is less diamagneticthan the sum of the diamagnetism of its components, the maximumanomalies occurring with anthracene and phenanthrene. However, only arelatively slight deviation from additivity is found for naphthalene picrate,in support of the assumption that the components are linked togetheronly by weak electrostatic f0rces.3~~ Susceptibilities of the tautomericforms of 8-hydroxyquinoline have been measured.350 Measurements ofx for solutions in benzene, pyridine, and quinoline suggest that in thesesolutions two-thirds of the hydroxyquinoline exists in the phenolic and one-third in the ketonic form.The fact that the isomeric pairs of p-chloro-, p-bromo-, and' p-nitro-benzenediazocyanide, and the two known forms of diphenyl-4 : 4'-bis-diazocyanide, have susceptibilities only slightly different has been taken inconjunction with other evidence as indicative of cis-trans-isomerism asdistinct from the cyanide-isocyanide relati0nship.3~1 C.M. French 352 hasdetermined x for a series of aliphatic acids and esters and evaluated Axm forthe methylene group, and W. R. Angus and G. Stott report values for aseries of isomeric aldehydes and ketones.353 The aldehydes are morediamagnetic than the ketones but the differences are small.Measurementsof the diamagnetic susceptibility of cyclooctatetraene support 8 cyclicstructure with conjugated double bonds rather than an aromatic type ofsystem, in agreement with infra-red and Raman spectra.140 J. R. Lacher 354has pointed out marked deviations in the experimental values, for poly-halogen derivatives of methane, from Pascal's additivity rule and haspresented an empirical interpretation on the assumption that the molecularsusceptibility is the sum of the atomic susceptibilities and six interactionterms directed along the edges of a tetrahedron. Evidence obtained byX-ray study of urea has been used355 to calculate its susceptibility by themethod of F. W. Gray and T. H. Cr~ikshank.3~~ No agreement wasobserved between the calculated and experimental values either for ureaor for its derivatives. Magnetic measurements on di-2-benzthiazolyldisulphide and di-(9-ethoxy-lO-phenanthryl) peroxide 357 show that the348 R.C. Sahney, S. L. Aggarwal, and 3%. Singh, J. Indian Chem. SOC., 1946, 23,335.349 F. G. Baddar md H. Mikhail, J., 1949, 2927.350 &I. Seguin, Bull. Soc. chim., 1946, 13, 566.361 D. Anderson, M. E. Bedwell, and R. J. W. Le FBvre, J., 1947, 457.352 C. M. French, Trans. Faruduy SOC., 1947, 43, 356.35s W. R. Angus and G. Stott, Nature, 1946, 158, 705.354 J. R. Lacher, J. Amer. Chem. Soc., 1947, 69, 2067.365 S. K. Siddhanta, J . Indian Chem. SOC., 1947, 24, 21.366 F. W. Gray and J. H. Cruikshank, Trans. Furaday SOC., 1935, 31, 1491.a67 H.C. Cutforth and P. W. Selwood, J . Amer. Chem. SOC., 1948, 70,278PINK : MAGNETOCHEMISTRY. 39former is dissociated to a considerable degree in toluene, but that the latteris diamagnetic in all cases and shows no temperature coefficient of sus-ceptibility. The magnetic method has also been applied to the study of thedisproportionation of diphenyl-p-t0lylmethy1.~~~ Measurement of thetemperature coefficient gives a value for the activation energy of 13.1 kcals.per mole of free radical. An interesting observation was made in the courseof this study : the free radical solution remained strongly coloured afterdisproportionation when the reaction was carried out in the dark; in thelight, however, colour and paramagnetism decreased in parallel.Themagnetic properties of bi-radicals have been reviewed.3593. Diamagnetism of Liquid Mixtures.-From measurements on the sus-ceptibilities of mixtures of aniline with ethyl, n- and iso-propyl alcoh01,~~~evidence has been obtained for the formation, in solution, of amine-alcohol‘‘ salts.” With methanol, however, the susceptibility is additive. Notabledepartures from additivity for mixtures of ethyl alcohol with o- and m-toluidine, pyrrole, pyridine, and quinoline have also been observed.361Similarly results have been obtained for mixtures of chloroform with aseries of ketones.362 The susceptibilities are additive except in the caseof acetone, where the slight anomaly may be explained by hydrogen bonding.Investigations of this kind might in principle be of value in elucidatinginstances of chemical interaction in solution, but it seems evident that theexpectation that data might become available which would be suitablefor tests of theories of the structure of liquids has not been realised.W. R.Angus and D. V. Tilston363 have surveyed the published work on liquidmixtures accumulated since the pioneer observations of A. W. Smith andA. W. Smith.364 Many of the data have been recalculated by a method,previously used by Angus and W. K. Hill,365 designed to bring out clearlyany real deviations from additivity. The conclusion is that although thebulk of the qualitative evidence supports small but real deviations fromadditivity, no quantitative measure of any accuracy can be derived.Itwould seem that much of the early work in this field has unfortunately beencarried out with materials whose purity has not been above suspicion.4. Magnetic Susceptibilities of Inorganic Compounds.-E. Grillot 366 hasconcluded that the law of additivity of magnetic susceptibilities is notapplicable to a series of twenty-three compounds of bivalent lead. P.Pascal, A. Pacault, and A. Tchakirian367 claim that, provided that thereis no marked structural constraint, the law of additivity is applicable to a356 W. Byerly, H. C. Cutforth, and P. W. SsIwood, J . Amer. Chem. SOC., 1948, 70,359 F. L. J. Sixma, Chem. Weekblad, 1947, 43, 437.360 S. Hatem, Compt. rend., 1947, 225, 332.361 Idem, ibid., p. 296.363 W. R. Angus and D. V. Tilston, Trans. Paraday SOC., 1947, 43, 221.364 A.W. Smith and A. W. Smith, J . Amer.*Chem. Soc., 1918, 40, 1218.s65 W. R. Angus and W. K. Hill, Trans. Paraday Soc., 1940, 36, 923.366 E. Grillot, J . Chim. physique, 1946, 43, 169.367 P. Pascal, A. Pacault, and A. Tchakirian, Compt. rend., 1948, 226, 849.1142.M. Seguin, ibid., 1947, 224, 92840 GENERAL AND PHYSICAL CHEMISTRY.series of germanium compounds. The main difficulty in evolving forinorganic chemistry anything comparable to the Pascal system of constantsin the organic field is that insufficient homologous series are available forcomparison and evaluation of atom and group susceptibilities. Usefulapplications of the magnetic method in the inorganic field neverthelesscontinue to accumulate. Magnetic measurements have shown that theperiodates of copper, nickel, cerium, and yttrium are true salts of theperiodic acids and not complexes.36s A magneto-chemical study of thepotassium chlorostannites 369 indicates that the hydrates of these com-pounds and stannous chloride itself are not simple molecular associationsof water and the corresponding salts.The molecular susceptibility ofpotassium stannichloride dihydrate agrees with the view that this compounddiffers from [SnC14(H20),]K2 only in the insertion of a molecule of water inthe crystal lattice. Interesting results have been obtained370 in a studyof nickel diformyldiethylenedi-imine-camphor. This compound is dia-magnetic in the solid state and in solution in benzene and acetone, butparamagnetic in methanol and other solvents.In a recent series of papers 371Sugden and his co-workers have reported x values for the ions of yttrium,samarium, gadolinium, and thulium. The rare earths were purified byfractional crystallisation controlled by measurements of magnetic sus-ceptibility. Crystallisation was continued until a series of successivefractions give the same x values. Measurements were made in solutionwith a Gouy apparatus for which an accuracy of a t least 1 part in 600 withdiamagnetics is claimed. This degree of accuracy is readily attainable atroom temperatures. A decrease of diamagnetism has been found, in thecase of lead bromide, from -0.275 x to -0.249 x after exposureto At the same time the salt loses 0.03-0.1% of bromine.This phenomenon may be associated with the photosensitivity of leadbromide. Susceptibilities are reported of cuprous nickelsalts in solution,374 potassium ferricyanide a t high ternperat~res,~’~ andcopper potassium sulphate a t temperatures below 1 O K.3765.Micro-wave Paramagnetic Resonance Absorption.-The discovery 377-379of the phenomenon of paramagnetic resonance absorption provides anew and direct method for the investigation of closely spaced energy368 R. Sahney, S. L. Aggarwal, and 31. Singh, J . Indian Chem. Soc., 1947,24, 193.368 E. Grillot, Compt. rend., 1948, 226, 496.37f S. Sugden et al., J., 1949, 131, 135, 136, 137, 139.378 I. Delgery, Compt. rend., 1947, 225, 398.373 M. L. Khanna, J . Xci. I d . Res. India, 1947, 6, B, 4.374 J.M. Alameda, An. real. Xoc. esp. Fds. Quim., 1947, 43, 689, 711.375 H. Masson, Compt. rend., 1947, 224, 1277.376 D. de Klerk, Physica, 1946, 12, 513.377 C. J. Gorter, ibid., 1936, 3, 503, 1006.378 E. Zavoisky, J . Phys. U.S.S.R.;1945, 9, 211; 1946,10, 197; R. L. Cummerow87* R. L. Cummerow, D. Halliday, and G. E. Moore, ibid., 1947, 72, 173 ; C. KittelI. Lifschitz, Rec. Trav, chim., 1947, 66, 401.and D. Halliday, Physical Rev., 1946, 70, 433.and J. M. Luttinger, ibid., 1948, 73, 162PINK : MAGNETOCHEMISTRY. 41levels in paramagnetic materials. Early experiments in this field 377were limited by unavailability of oscillators of sufficiently high fre-quency, a want remedied by the great war-time advances in micro-wavetechnique. In a typical experimental arrangement,378) 380 the absorptionis measured as a function of the magnitude of a static magnetic field appliedin a direction perpendicular to a magnetic field, fluctuating with a frequencyof 9375 mc./sec.The salt is placed in a circuit element situated betweenthe poles of the electromagnet. As the static field is varied, the powerabsorption of the salt is found to pass through well-defined maxima. Suchparamagnetic losses have been investigated for salts of the iron group381and for chromic ammonium a l ~ m . 3 ~ ~ Extension of such measurementsshould throw light on the existence and prevalence of magnetic exchangecoupling between ions. Theoretical aspects have been dealt C.Kittel has discussed the theory of ferromagnetic resonance a b s o r p t i ~ n .~ ~Developments in this field may be awaited with great interest.6. Miscellaneous Problems.-The effect of cold-working on the magneticsusceptibility of copper and aluminium has been examined.385 The dia-magnetic susceptibility of copper decreases rapidly to 15% below theannealed value and then rises slowly with increased cold working. Theparamagnetic susceptibility of aluminium decreases similarly to a similarextent. The effects appear to be associated with lattice distortion andgrain fragmentation. Negative results were obtained 386 in experimentsaimed at the detection of super-conductivity in rapidly cooled solutions ofsodium in liquid ammonia at 78" and 195" K. by measurement of x for thesolutions by the Gouy method.Measurements of the magnetic anisotropy are reported on rn~lybdenite~~'on nickel ions in ~rysfals,38~ and on a large number of crystals and naturallyoccurring substances including m i ~ a .3 ~ ~ A synthetic mica has been found 390to be quite strongly paramagnetic, but the paramagnetism is attributed toinclusions of Fe304 since the susceptibility decreases with increasing fieldstrength and much of the iron content can be removed by dilute sulphuricacid. The diamagnetic susceptibilities of alkali-metal salts dissolved infused borax were claimed 391 to be greater than for the pure salts, pointing380 P. R. Weiss, Physical Rev., 1948, 73, 471.381 R. L. Cummerow, D. Halliday, and G. E. Moore, ibid., 1947, 72, 1233.382 P. R. Weiss, C. A. Whitmer, H.C. Torrey, and J. S. Hsiang, ibid., p. 975;D. M. S. Bnguley and J. H. E. Griffiths, Nature, 1947,160, 532; R. Bleaney and R. P.Penrose, Proc. Physical Soc., 1948, $0, 395.383 C. Kittel and J. M. Luttinger, Physical Rev., 1948, 78, 162; C. J. Gorter andJ. H. Van Vleck, ibid., 1947, 72, 1128.384 C. Kittel, ibid., 1947, 71, 270; 1948, 73, 155.386 T. S. Hutchison and J. Reekie, ibid., 1948, 73, 517.386 R. B. Gibney and B. L. Pearson, ibid., 1947, 72, 76; cf. refs. 294, 295.s87 A. K. Dutta, Indian J . Physics, 1945, 19, 225.s88 A. Mookherji, ibid., 1946, 20, 9.380 P. Nilakantan, J . Indian I n s t . Sci., 1941, 23, G, 1, 41, 59, 95, 100, 161.380 J. T. Kendall and D. Yeo, ATature, 1948, 161, 476.3g1 S. K. Majumdar and R. P. Banerjee, Indian J .Physics, 1946, 20, 21842 GENERAL AND PIXYSICAL CHEMISTRY.to increased electronic orbits or an enlargement of the crystal lattice. Thisconclusion is not confirmed by molecular refraction and X-ray diffractionstudies.experiments have been described BB3 in whichthe polymerisation of pure vinyl chloride was followed by susceptibilitymeasurements. In this connection another effect has been noted 394 whichmay be of general significance. Polyindene fractions polymerised to differentdegrees (2.45-7.39) were measured by the cylinder method, The plot ofx against degree of polymerisation shows a distinct maximum at a mediumdegree of polymerisation (-5). The rise in x is easily explained in terms ofthe decrease in double bonds with increasing polymerisation, but the originof a paramagnetic component leading to a fall in x a t higher degrees ofpolymerisation is not so readily explained.Eollowing earlierR.C. P.12. METALS AND ALLOYS. THE PAULING HYPOTHESIS.1. Introduction.-In recent years much interest has been aroused by aseries of papers by L. Pauling in which attempts are made to develop atheory of metals and alloys from a viewpoint different from that usuallyadopted. The non-specialist reader may find it difficult to distinguishbetween the real conclusions or predictions of the theory on the one hand,and its empirical or ad hoc assumptions on the other, and the present reportis an attempt to clarify the position.The early theories of Drude and Lorentzin which the electrons were treated as particles of a gas obeying the classicallaws led to the well-known difficulty that the observed specific heats ofmetals could not be reconciled with the presence of electrons to a numberof the same order as that of the atoms, this number being required by theelectrical and optical properties.The first step towards the removal of this impasse was taken in 1928 bySommerfeld who treated the electrons as particles of a gas obeying theFermi-Dirac statistics.In this case the small mass of the electrons meansthat if they are present to the extent of 1 - 4 electrons per atom, the resulting" electron gas " is almost completely degenerate 397 at room temperatures,and has a very small specific heat which is approximately proportional tothe absolute temperature.In this way the presence of a number of electronsof the order to be expected from the normal valencies of the metals could bereconciled with specific heats accounted for almost entirely * by the thermal398 J. Farquharson, Trans. Paraday SOC., 1936, 32, 210; J. Farquharson and P.Ady, Nature, 1939, 143, 1067; S. S. Bhatnagar, P. L. Kapur, and G. Kaur, J .Indian Acad. Sci., 1949, 10, A , 468: J . Indian Chem. Soc., 1940, 17, 177.The free-electron gas theory.393 0. Tanaevsky, Compt. rend., 1947, 225, 1069.39* W. Schutzner, Nature, 1949,164, 364.397 For an elementary description of these ideas and a general review of the electrontheories of metals, see W. Hue-Rothery, " Atomic Theory for Students of Metallurgy "(Institute of Metals Monograph Series).* At very low temperatures the electronic specific heat is a relatively greaterfractionHUME-ROTHERY : METALS AND ALLOYS.43oscillations of the atoms. The Sommerfeld theory still required free pathsmuch longer than were really consistent with the mathematical treatment,but the introduction of the ideas of the Fermi-Dirac statistics marked animmense advance.The idea of an electron gas was clearlytoo simple, and in the later developments of the theory associated with thenames of Bloch, Brillouin, Mott, and Jones the methods of wave-mechanicsare applied to the motion of electrons in a 3-dimensional periodic fieldwhose periodicity is that of the crystal lattice. In this case, if, as at theabsolute zero, the periodicity of the field is perfectly regular, the wave-likecharacteristics of an electron enable it to move unimpeded through thelattice,? and the long free-paths indicated by the electrical conductivitiescan be understood. The state of an electron in a crystal lattice can beexpressed by its wave-number 1 / A , where h is the associated wave-length.I n practice it is customary to multiply the wave-number l / h by 2x, andthe quantity - is called the waue-number k ; it is a vector quantity whichcan be used to describe the state of an electron.The wave-like charac:teristics of an electron then mean that, for electrons whose states lie in anyone direction of k, there will be certain values of k for which the electronicwave-length satisfies the conditions for a Bragg reflection by atomic planeswithin the crystal.Electrons in such states cannot move freely throughthe crystal, and the effect of this is that for each direction of k: there areranges of forbidden energies which separate the bands or zones of permittedelectron energies. These developments have led to a successful interpret-ation of the three main types of substance, insulators, semi-conductors, andnormal conductors, and have thrown much light on the electrical propertiesof metals, and on the structures of some alloys.398* 399Calculation of physical properties. It is desirable to emphasise theextent to which the electron-band theory of metals, using the very minimumof assumptions, has led not only to a general explanation of a wide rangeof phenomena, but to quantitative calculations of the physical constantsof crystals.In some of the more refined calculations using a Hartree self-consistent field method, the atomic field is calculated by assuming onlythe mass and charge of the electron, and the atomic number of the atomThe electron-band theory.*2xh3Q8 For an elementary account of this work see ref. 397, Part V, p. 179, and A. H.Cottrell, “ Theoretical Structural Metallurgy,” Edward Arnold.3Q8 For more detailed treatments see N. F. Mott and H. Jones, “The Theory ofthe Properties of Metals and Alloys,” Oxford Vniversity Press.* For abbreviation we use the term electron-band theory to include both thesimple Brillouin zone theories and the more detailed theories in which the atomicfield is considered, and a, p , or d functions are introduced.t It can be shown that this conclusion is not affected by the zero-point energy ofthe atomic vibrations.$. In the free-electron theory the direction of k is the direction of motion of theelectron, but in a periodic field the electron does not always move in the same directionas k44 GENERAL AND PHYSICAL CHEMISTRY.or ion concerned. This atomic field is then introduced into a calculationof the Wigner-Seitz 400 type in which the only additional assumption madeis that of the type of structure in which the metal crystallises. With noassumptions other than these the theory has been able to calculate thelattice spacings, binding energies, and compressibilities of the alkali metals,lithium and sodium, and of the bivalent metal, beryllium.H. Jones401has also shown that the theory accounts satisfactorily for some propertiesof close-packed hexagonal crystals, and particularly for the variation oflattice spacing with composition in alloys. It is thus reasonable to saythat by assuming nothing but the mass and charge of the electron, theatomic number, and the type of crystal structure, the theory has permittedthe calculation of a wide range of physical properties.* I n the alkali metalsthe ions are small compared with the shortest distances between the atoms.Such metals may be called “ open ” metals in contrast to “ full ” metals,such as copper, where the electron clouds of the ions in the metallic crystaloverlap to such an extent that the compressibility is determined more bythe ionic overlap than by the valency electrons.For copper Fuchs’stheoretical calculations 402 are in reasonable agreement with the observedcompressibility although the calculations here involve the introduction ofsome empirical assumptions, and are thus not so completely fundamentalas those referred to above. For elements of higher valency the calculationsbecome increasingly difficult but approximate solutions have been obtainedfor alumini~rn,~O3 iron>@ and tungsten.405 All this represents a substantialachievement of quantitative theory. The theory has failed to explain thephenomenon of supraconductivity. Otherwise there is little in contradictionto it as regards the properties of the perfect crystal lattice, and for theseproperties the general impression is that further development is a matter ofovercoming the mathematical difficulties.The mechanical properties ofmetals outside the elastic range depend largely on the secondary structureof the actual crystal, Le., the structure involving mosaics, dislocations,lattice defects, etc., and it is a weakness of the theory that it does not lenditself readily to the calculation of such effects.2. The Pauling Hypothesis.-The first paper by Pauling406 on metallicbonds appeared in 1938 and was concerned mainIy with the metals frompotassium to copper, and with the corresponding elements of the later400 E. Wigner and F. Seitz, Physical Rev., 1933, 43, 804; 1934, 46, 509; E.Wigner,Physical Rev., 1934,46, 1002 ; J. Bardeen, J . Chem. Physics, 1938, 6, 367. For generalreviews see refs. 397 and 399.401 H. Jones, PhySicu, 1949, 15, 13 (Discussion 21).402 K. Fuchs, Proc. Roy. SOC., 1935, A , 151, 585; 1936, A , 153, 622.403 Z . Matyas, Phil. Mug., 1948, 39, 429; 1949, 40, 324.404 M. F. Manning, Physical Rev., 1943, 63, 190; J. B. Greene and M. F. Manning,*05 M. F. Manning and M. I. Chodorow, ibid., 1939, 56, 787.406 L. Pauling, ibid., 1938, 54, 899.* It will be appreciated that the elastic constants permit the calculation of theibid., p. 203.characteristic temperature of a crystalHTJME-ROTHERY : METALS AND ALLOYS. 45periods of MendelGev’s table. I n each Long Period there is a markeddecrease in atomic diameter * on proceeding from the alkali metal to themetals in Groups 11, 111, IV, and V.On passing to Group VI the atomicdiameter still decreases although to a lesser extent, and then in Groups VIIand VIII the atomic diameters become approximately constant, and showa slight increase on passing to copper, silver, and gold in Group IB. Thesegeneral effects are summarised in Fig. 1, and clearly suggest that the firm-ness of the atomic binding in the metallic crystals increases to a maximumin the region of Groups VI-VII.The same general conclusion is reached by a study of the melting pointsof the elements which in all three Long Periods reach a maximum inGroup VI.The reciprocal of the compressibility, which may be called the incom-pressibility of a metal, indicates the difficulty with which the atoms can bepulled apart, and is thus a measure of the strength of binding.I n theelements of the Long Periods the incompressibilities rise to maxima in theregion of Group VI, and thus again suggest that the atomic binding isstrongest in this region.In the electron-band theory of metals the assembly of electrons is con-sidered as a whole, and the mathematical treatment develops from theconsideration of the properties of the assembly in a uniform potential (free-electron theory) to that of their behaviour in a simple periodic field, andthen to more complicated developments in which the wave-functions in theregion of the atoms are assumed to have symmetry characteristics resemblingthose (s, p , d functions) of free atoms.Each electron is represented by awave-function extending over the whole crystal, and the emphasis is on thecrystal and the assembly as a whole. I n contrast to this the Pauling theoryapproaches the problem by considering the behaviour of the electrons inthe immediate vicinity of each atom, and deals particularly with the numberof electrons concerned in binding an atom to its immediate neighbours.Ideally, each method of approach if pushed sufficiently far would lead to acomplete solution of the problem of the structure of metals.In Pauling’s fmt paper406 the conclusion is reached that the metallicbond is closely related to the ordinary covalent or electron-pair bond. Thisconclusion had previously been advanced by V.M. Goldschmidt 407 whoregarded the typical covalent diamond structure as commensurable withthose of the metals. The alkali metals crystallise in the body-centredcubic structure in which each atom has eight close neighbours at a distance0.866 a (where a is the side of the unit cell) and six further neighbours a t adistance a. In these metals, according to Pauling, the atomic bondinginvolves four orbitals of each atom (one s and three p ) , and the metallicbond results from resonance between all the possible arrangements of the*O7 V. M. Goldschmidt, 2. physikal. Chem., 1928, 133, 397.* The atomic diameter is taken to be the closest distance of approach betweentwo atoms in the crystal of the elementFIG. 1.(b)7st Long period, 5K4343i,@Bod’- centped cubic structure.face -centred cu6ic structure. @The interatomic distances of the elements.[The crystal structure of a-manganese is complex, and the interatomic distances vary[Reproduced, with permission, from @‘Electrons, AtomsHUME-ROTHERY : METALS AND ALLOYS. 47available electrons in one- or two-electron bonds between the 14 closeneighbours of each atom.The transition elements are those in the free atoms of which an octet(w2, np6) of electrons expands into a group of 18 electrons (m2, np6, &lo)by the building up of a sub-group of ten d electrons. Pauling assumes thatin the crystals of these elements the bonding involves the d orbitals, sothat there are altogether 9 orbitals to be considered (one s, three p , andfive d).* Pauling then interprets the characteristics of Figs.l ( a ) and l(6)by assuming that on passing from potassium to vanadium the numbers ofbonding electrons increase in unit steps from 1 to 5 per atom with a regularincrease in the number of covalent bonds between which resonance canoccur, and consequently with a steady increase in the strength of thecohesion. Since the covalent bonds involve paired electrons of oppositespin this interpretation accounts for the fact that the metals concerned areneither strongly paramagnetic nor ferromagnetic in spite of the presence ofan incomplete d shell.In order to account for the existence of an almost constant atomicdiameter after Group VI (see Fig. 1) Pauling assumes that some of the dorbitals are not available for bond formation, and from a consideration ofthe saturation moments of the ferromagnetic metals, iron, nickel, and cobalt,he concludes t that of the five 3d orbitals, 2.56 are concerned in bond forma-tion, whilst the remaining 2.44 orbitals are atomic d orbitals which do not takepart in binding the atoms together, and in which the electrons enter so asto have the same spin as long as this is possible, in accordance with theprinciple of maximum multiplicity.These non-integral numbers or orbitalsrepresent a situation in some ways the same as if at a given instant someatoms were in one state and some in another, the fractional number beinga time-average. Pauling assumes that in chromium 0.22 electrons per atomAtomic d orbital.- Metal.+Cr ......... 0.22 0Mn ......... 1.22 0Fe ........ 2-22 03.22&CO ......... 2.44 0.784.22 - Ni ......... 2.44 1.78Total numberSatn. moment, of electrons in Totalbonding 3d number ofassumed. observed. hybrid orbital. electrons.0.22 - 5.78 61-22 - 5.78 72-22 2.22 5.78 81.66 1.61 5.78 90.66 0.61 5-78 10have entered the atomic orbitals, and that this number increases by unityfor each step along the Periodic Table. In this way the above scheme is408 &I. F. Manning and H. M. Krutter, Physical Rev., 1937, 51, 761.* Manning and Krutter 408 had previously shown that for calcium in the First LongPeriod the approach of the atoms is sufEciently close for the 49, 4p, and 3d bands tooverlap, so that the valency or bonding electrons are in hybrid 9, p , d states.t This section describes the first of Pauling’s papers and the details are slightlymodified later (see p. 49)48 GENERAL AND PHYSICAL CHEMISTRY.drawn up for the electronic distribution in the crystals of the elements con-cerned. This scheme requires the number of bonding electrons to be roughlythe same in the whole series of elements from chromium to nickel. It showsthat (subject to the empirical assumptions of the numbers involved) on pass-ing from chromium through manganese to iron the numbers of electrons peratom in the atomic d orbitals will be less than the number of orbitals (2-44),so that all these electrons can have the same spin with a correspondingincrease in the saturation moment. On passing to cobalt the number ofelectrons to be distributed among the d orbitals (3.22 per atom) is greaterthan the number of orbitals (2.44), and so some of the atomic 3d electronswill be paired, with a resulting saturation moment 2.444.78 = 1.66,whilst on passing to nickel the saturation moment is 2.44-1.78 = 0.66.The scheme requires a maximum saturation moment to be shown at23% of the way between iron and cobalt, and experimentally the atomicsaturation moment of iron-cobalt alloys rises to a maximum a t 26 atomic-%of cobalt.It must be emphasised that the choice of these numbers is a purely adhoc assumption made in order to agree with the observed saturation moments.The general idea that the number of electrons per atom involved in bondingincreases from 1 to 5 per atom on passing from Group IA to Group VA isit reasonable and straightforward interpretation, but the scheme gives noexplanation of the maximum cohesion observed in Group VIA.Thesplitting of the d band was not a new idea since it had been shown as longago as 1928 by BetheM9 and is an inevitable consequence of the assemblyof the atoms into a crystal structure. The Pauling theory interprets butdoes not explain the magnetic properties, since the assumptions were chosenso as to agree with the experimental facts. Pauling assumes that thebonding 3d electrons are those whose wave-functions overlap appreciably,whilst the atomic 3d orbitals overlap less and can consequently give riseto the positive exchange integral involved in ferromagnetism.This generalpicture of the building up of an inner core of 3d electrons on passing fromGroup VI to Group VIII appears very probable. It provides a differencebetween atoms of nearly the same atomic radius, and this may be one of thereasons 4lO why superlattices are formed in solid solutions in these elements.This fact could not be understood in terms of older theories because thewide solid solution in the systems Fe-Co, Fe-Ni, and Co-Ni suggested aclose similarity of the atoms, and some difference was needed to explainwhy the ordered structures were formed.The Pauling view of the transition elements was thus an attractiveinterpretation, and the idea that the d orbitals are concerned in the metallicbonding is confirmed not merely by the more refined band theories4M*405in which d functions are introduced, but also by the chemistry of co-ordination compounds which has been successfully interpreted in terms40B H.Bethe, Ann. Physik, 1928, 87, 55; 1929, 3, 133.*lo W. Hwne-Rothery and J. W. Christian, PhiE. Mag., 1946,36, 835HUME-ROTHERY : METALS AND ALLOYS. 49of hybrid s, p , d orbitals. More doubt exists about the extension of thetheory to copper, silver, and gold which was dealt with only very brieflyin the first paper 406 but developed in detail later (see below).3. Co-ordination Number and Bond Radii of the Metal Atoms.-In thelater extension of the Pauling theory the essential assumption made isthat in copper, silver, and gold, and in the succeeding elements in thePeriodic Table, the outermost d electrons of the ions are still involved in themetallic bonding, so that in zinc, for example the bonding electrons are inhybridised ( 3 4 48, 4p) orbitals.By means of the empirical methodsdescribed below, which are based on the interpretations of observed bondradii, it is then concluded that the valencies (i.e. the numbers of electronsper atom involved in resonating covalent bonds) of the elements in Groups IB,IIB, and IIIB are 5.44, 4.44, and 3.44, respectively. This is in completecontradiction to all earlier theories and it seems doubtful whether a valencyof 4.44 for zinc can be reconciled with the data of Beardea et d 4 1 1 for softX-ray absorption and emission, since these results suggested that the 3delectrons were too deep down in the atom to be affected by alloying. Inview of the satisfactory quantitative theory of the zinc crystal in terms ofthe normal valency of 2, the new valencies should be regarded with suspicionuntil they receive quantitative confirmation ; that they are not impossibleis shown by the existence of co-ordination compounds of copper in which(spd) hybrid orbitals are involved.In Pauling’s second paper 412 an equation is used to express the relationbetween the apparent atomic radius and the bond number (which may befractional), the bond number being the number of shared electron pairsinvolved.The equation iswhere n is the bond number, Le., the number of shared electron pairsinvolved in the bond. This is empirical although the type of law has apartly theoretical basis in terms of the number of canonical structures.The value of C is empirical and may not be constant. This relation is thentested by comparison between the bond lengths (i.e.the distances betweenclosest neighbours) in the face-centred cubic and body-centred cubicmodifications of iron, titanium, zirconium, and thallium which crystallise inboth structures. If the co-ordination number of the body-centred cubicstructure is taken to be 8, the empirical relation is not confirmed, and thisis taken to indicate that an individual atom is bonded not merely to its8 closest but also to the 6 next closest neighbours. Attempts to obtain anempirical equation which covers all the data are unsuccessful, and Paulingtherefore drops the empirical equation, and uses the data from the abovefour elements to construct a curve from which the radius for co-ordinationnumber 12 can be deduced when an element crystallises in the body-centred4l1 J.A. Bearden and H. Friedman, Physical Rev., 1940, 58, 387; J. A. Beardenand W. W. Beeman, ibid., p. 396.418 L. Pading, J . Anaer. Chena. Soc., 1947,6$, 642.R, - 22% = C lo50 GENERAL AND PHYSICAL CHEMISTRY.cubic structure. This procedure means, of course, that the finer detailsof the atomic radii which are later deduced are not related to fundamentalcovalent-bond theory but are based on arbitrary relations deduced frommetallic structures themselves. A further objection to Pauling’s procedureis that the four elements used to deduce the correction curve are all of variablevalency, and there is no reason why the different allotropic forms shouldrefer to atoms with the same number of valency electrons.Subject to the above assumption, Pauling then deduces a series of metallicradii, R12, for co-ordination number 12, and a corresponding series of single-bond radii, R,, obtained from the empirical equation by assuming that thebond number is vf12 where v is the valency of the element.In this partof the paper there appears to be confusion between observation, interpret-ation, and theory. I n the case of a- and p-manganese, for example, thecrystal structures are abnormal with several close interatomic distances,and ever since the original work of A. J. Bradley413 in 1927 it has beensuggested that these structures contain atoms in two or more electronicstates. Pauling assumes the existence of the abnormal structures, and byapplying his empirical relations to the varying inter-atomic distances is lednaturally to the conclusion of the existence of atoms of differing valencies.He then states that, “This fact explains the occurrence of this unusualatomic arrangement.” The circular nature of the argument is a t onceobvious. The only established fact is the abnormal crystal structure; theremainder of the discussion is empirical assumption or interpretation.Thecase of chromium which is assumed to crystallise in both body-centredcubic and close-packed hexagonal structures is discussed in detail but israther unconvincing because the careful work of Grube and Knabe *14makes it probable that this metal crystallises only in the body-centred cubicstructure ; the supposed modification with a close-packed hexagonal struc-ture is presumably caused by the presence of hydrogen absorbed duringelectrolytic deposition.*In the later part of the second paper 412 Pauling compares the single-bond radii deduced as described above with other atomic radii (tetrahedralradii, octahedral radii, radii from metal hydrides, etc.).In the series of413 A. J. Bradley and J. ThewIis, Proc. Roy. SOC., 1927, A, 115, 456.4 l 4 G. Grube and R. Knabe, 2. Elektrochem., 1936, 42, 793.415 A. J. Bradley and E. F. Ollard, Nature, 1926, 117, 122.d f 6 H. Sasaki and S . Sekito, Tram.Electrochem. Soc., 1931, 59, 437.* The resistance/temperature c m e was determined by Grube and Knabe up to1800” and showed a very slight irregularity a t about 1580”. The discussion in thepaper makes it clear that this was almost certainly connected with the oxide contentof the metal, and did not indicate a polymorphic transformation. The hexagonalmodification was first described by Bradley and Ollard415 and later by Sasaki andSekit0.4~~ Both these observations were made on electrodeposits, and in the dis-cussion on the paper of Sasaki and Sekito the suggestion was made that the hexagonalform occurs only in the presence of hydrogen, and that the body-centred cubic form isproduced when the hydrogen is given off. The hexagonal modification is included inmost collected tables of crystal structures, but is clearly not sufficiently well establishedfor the pure metal to justify a detailed discussion of interatomic distancesHUME-ROTHERY : METALS AND ALLOYS.51elements Na to Cl, the new single-bond radii are in good general agreementwith the other radii, but in the series Li to F, and in the later elements ofthe Periodic Table, there are discrepancies which are explained only byintroducing assumptions which are as numerous as the facts explained.The second paper by Pauling thus emphasises what was only brieflyreferred to in the first paper, namely the high valencies ascribed to copper(5.44), zinc (4.44), and gallium (3.44). The paper contains little whichconfirms these arbitrary assumptions, and little or nothing which explains,predicts, or generalises the data in a useful way, and none of the doubtfulpoints contained in the 1938 paper is removed.4.BrilIouin Zones and Alloy Structures.-In the band theory thesymbol N(E) is used to denote the number of electronic states per unitvolume of metal with energies between E and E + dE, and diagrams aredrawn in which N(E) is plotted against E, and the region of states occupiedN(E) 1 AFIG. 2.a t the absolute zero is shaded. We may imagine the electron states to beshown in a 3-dimensional wave-number diagram with the components(&, k,, kz) of the wave-number k as co-ordinate axes. In the free-electrontheory the states occupied by electrons at the absolute zero occupy a spherein the wave-number diagram, and the surface of this sphere is called thePermi Surface.It can readily be shown that this sphere of occupied statesleads to the relation N(E)ccE* and the N(E) curves of the free-electrontheory are thus of the form shown in Fig. 2(a). As explained above(p. 43), the wave-like characteristics of the electron mean that for eachdirection of the wave-number, there are critical wave-lengths which satisfythe condition for reflection by planes of atoms within the crystal, and it canbe shown that as the wave-number is increased there is a sudden increasein energy a t each of these critical wave-numbers. The critical wave-numbers lie on planes in E-space, and these planes bound the so-calledBrillouin Zones. If now we represent the electron states in a 3-dimensionalk-space diagram we find the latter divided into a number of polyhedralzones; inside these zones the energy increases continuously with the wave52 GENERAL AND PHYSICAL CHEMISTRY.number, whilst there is an abrupt increase in energy on passing from a statejust within the zone to one lying just outside.It follows therefore that onincreasing the number of electrons per unit volume, the Fermi surfaceexpands until it touches the surface of the first Brillouin zone. At thisstage the abrupt increase in energy on passing through the zone boundarymeans that on further increasing the number of electrons they do not atfirst pass into states lying outside the zone; this naturally produces a fallin the N(E) curve which takes the forms of Fig.2(b) or (c). If the energygap a t the surface of the zone is sufficiently large, an increasing number ofelectrons will result in the whole of the states of the first zone being occupiedbefore any electrons enter the states of the second zone, and the curves forthe two zones will be separated as shown in Fig. 2(b). If, on the other hand,the energy gap is relatively small, the lowest states of the second zone mayhave lower energies than the highest states of the first zone, and in this casethe two N(E) curves overlap as shown in Fig. 2(c). This second kind ofcurve is characteristic of most metallic structures.In a pure metal the number of electrons per atom is fixed, but if we alloya metal with one of higher or lower valency we can increase or decrease theaverage number of valency electrons per atom, and in this way can producea variation analogous to that referred to above.Referring to Fig. 2 it canreadily be seen that on increasing the number of electrons so that theoccupied states increase from A to B, the rapid fall in the N(E) curve willmean that a larger increase in energy is involved for each electron added.*In H. Jones’s theory 417 it was therefore concluded that, on adding an elementof higher valency to one of lower valency, a given crystal structure wouldtend to become relatively unstable when the electron concentration (ie., thenumber of electrons per atom) reached the value denoted by the region A-B inFig. 2, because if all other possible crystal structures were considered therewould probably be one of them whose N(E) curve remained high, and whichcould therefore accommodate the electrons with a lower energy.In the sameway a structure whose N(E) curve rose to a pronounced peak as a t A inFig. 2 would tend to be stable a t this electron concentration because thehigh N(E) curve would mean that the electrons were accommodated with alow energy. The Jones theory can be summarised by saying that, so far asthe electronic energy is concerned, alloys tend to assume structures whoseN(E) curve is high 7 and which can therefore accommodate the electronswith a low energy. This theory was applied with conspicuous success tothe structure of y-brass. It so happens that for this structure the shape ofthe first Brillouin zone is not very different from that of a sphere, with theH.Jones, Proc. Roy. SOC., 1934, A , 147, 225, 396; Proc. Physical SOC., 1937,49, 250. * The Jones theory applies only to alloy systems where the constituent atoms areof similar size and electrochemical characteristics, so that the structure is determinedpredominantly by the electron concentration.-f A high N(E) curve means a large number of energy states of the value concernedso that a given increase in the number of electrons involves a relatively small increasein the maximum energyHUME-ROTHERP : METALS AND ALLOYS. 53result that the N(E) curve (Fig. 2) falls very steeply from A to B to C, andthe number of electron states per atom in the complete zone is not muchgreater than that corresponding to the peak at A .This led to a mostunfortunate position in which the Jones theory was misunderstood as beingone which indicated that stability would be produced by a number ofelectrons suflicient to fill a zone completely. The true position is as explainedabove, and in metallic structures there is nothing to suggest that anystability is conferred by a number of electrons which suffice to fill a zone.*In the third development of the Pauling hypothesis, Pauling andE ~ i n g , ~ ~ ~ attempts are made to extend the Jones theory to the structureof @-brass, y-brass, a-manganese, and @-manganese by assuming that theelements exert the valencies of the Pauling hypothesis (Cu 5.4, Zn 4.4,Ga 3.4) instead of the usual valencies (Cu 1, Zn 2, Ga 3).The use of thevalencies deduced from the interatomic distances in crystal structures ofthe elementis involves the assumption that these valencies are constants ofthe elements and independent of the crystal structure. This appearsimprobable if the non-integral values are to be interpreted as averages ofwhole-number valencies.It is well known that in the so-called electron compounds a phase of a givenratio of valency electrons to atoms when the elements are given their normalcrystal structure tends to occur at definite valencies (e.g., Cu 1, Zn 2, Ga 3).Pauling and Ewing show what had not previously been appreciated, namelythat the principle would still apply if the valencies of the same elementsdiffered by steps of - 1 (e.g., Cu 5-4, Zn 4.4, Ga 3.4), instead of by +1 onpassing along the series.?The use of Pauling valencies does not therefore invalidate the empiricalrelation between crystal structure and electron concentration, but thearbitrary procedure by which some of the d electrons are included in thezones whilst others are omitted has been criticised by N.F. Mott.*19 Apartfrom this, most of Pauling and Ewing’s discussion is unfortunately basedon the assumption that the number of electrons required to fill a zone isthe significant quantity. For y-brass where the properties indicate anearly full zone this misunderstanding is not serious. For @-brass it is,*18 L. Pauling and F. J, Ewing, Rev. Mod. Physics, 1948, 20, 112.*l9 N. F. Mott, “ Discussion at Amsterdam Conference on Metals,” 1948.* I f a substance is an insulator with an N(E) curve of the type of Fig.2 ( b ) , a structurewith a completely filled first zone may be regarded as more stable than one with a fewmore electrons, because of the abrupt increase in energy from A to B. In the genera1case of overlapping zones, there is no reason why the number of electrons required tofill a zone should be significant.t Thus the &brass structure occurs a t composition CuZn, Cu5Ga, CuSSn, and ifCu, Zn, Ga, and Sn are assigned valencies of 1,2,3, and 4 respectively, these compositionscorrespona to an electron : atom ratio of 3/2. If the valencies had been taken as Cu,5.4, Zn = 4.4, Ga = 3-4, and Sn == 2.4 the electron : atom ratios of the above com-position would be16.2 + 3.4 = 4.9, Cu,Sn - 27 + 2.4 4.9.4 6 CuZn = 5*4 = 4.9, ~ u , ~ a =54 GENERAL AND PHYSICAL CHEMISTRY.however, most unfortunate that the theory of Jones which predicts thepeak on the N(E) curve of Fig. 2 a t the observed electron concentrationof 1.48 should be dismissed by Pauling and Ewing because this value doesnot correspond to a completely filled zone. The attempts to show that largezones can be obtained which are nearly filled at the electron concentrationrequired by the high valencies are thus of little significance. Apart fromthis, Pauling and Ewing’s treatment is inconsistent in that the zone for@-manganese is regarded as associated with reflections weaker than thosewhich are completely ignored in dealing with other structures.Paulingand Ewing 418 are also incorrect in suggesting that the concept of a sphericalFermi surface can be reconciled with the high valencies of their assumptions.The assumption of a spherical Fermi surface is a reasonable approximationwhen the number of electrons is small and they are essentially of an s type.It is, however, well established 419 that, when p and d functions are incor-porated, the Fermi surface is often entirely different from that of a sphere.It does not seem unreasonable to say, therefore, that Pauling and Ewing’sapproach involves misunderstandings and inconsistencies which preventit from providing any real confirmation of the Pauling hypothesis.5. Metallic OPbitals.-In the later developments of the Pauling hypothes-is, the picture is slightly modified.The number of atomic non-bonding dorbitals is still assumed to be 2.44 per atom. Since the total number of(s, p , d ) hybrid orbitals is 9 per atom, this leaves 9 - 2.44 = 6-56 orbitalsper atom to be accounted for. The figures given previously indicate thatnot all of these orbitals are used, and in the later papers * 420, 421 Paulingassumes that 5.78 orbitals per atom are involved in the formation of stable(spd) bonding orbitals, and that the remaining 0-78 orbitals per atom, whichare called metallic orbitals, are a characteristic of metals and are necessaryto permit unsynchronised resonance between the individual valency bonds.In all cases the fractional numbers are to be interpreted as averages, so thatin the structures concerned about three quarters of the atoms possess theextra metallic orbital.This concept is used to discuss the structure ofwhite tin in which the interatomic distances are markedly greater than ingrey tin (diamond structure). The conclusion is reached that in white tinthe valency is less than 4, a suggestion which had been made from simplerconsiderations as long ago as 1936.422 The picture of white tin presentedby Pauling involves the existence of (a) neutral bivalent atoms, (b) ter-covalent tin atoms with a negative charge, and (c) uni-covalent atoms witha positive charge. This is essentially an interpretation of the interatomicdistances and is not supported by any other quantitative evidence.020 L. Pauling, Proc. Roy. Soc., 1949, A , 196, 343.4z1 L. Pauling, J., 1948, 1461.422 W. Hume-Rothery, “ The Structure of Metals and Alloys,” Institute of MetalsMonograph Series, 1936.* Some confusion in publication appears here since in the 1949 paper 420 it is statedthat this conclusion was reached in the earlier papers 40% 412 whereas actually thesecontain no references to the metallic orbital, although it can be seen from the 1947paper 412 that a11 the orbitals were not being usedHUME-ROTHERP : METALS AND ALLOYS. 55The implications of the assumption of the ‘‘ metallic ” orbital have beendealt with fully by Pauling in his 1949 paper a20 vhich begins by discussingthe relative proportion of s and p character in the bonding orbitals of thediatomic molecules Li,, Na2, K,, Rb,, and Cs,, and of the orbitals in thecorresponding metals as interpreted by the resonance-bond hypothesis.This discussion is interesting and suggestive. In the remainder of thispaper increasing emphasis is placed upon the interpretation of the fractionalvalencies of the earlier papers as being averages of integral valencies, andspeculations are made regarding the actual valencies of which the fractionalvalues represent the average. The further hypothesis is then advancedthat a special stability will be found if the resonance results in a simpleratio of the number of bonds to the number of positions, so that a specialstability is associated with bond numbers which are simple fractions (i,4, 8, . . .); the importance of a bond number equal to Q had previouslybeen emphasised by Rundle.*,3 These considerations are then used todeduce a system of single bond radii, and of metallic radii for the metallicatoms in different valency states. This treatment requires slight modific-ations to be made to the valencies described in ( b ) and (c), but the generalpicture remains unchanged. It is legitimate to claim that the radii deducedform a consistent scheme, but it should be emphasised that the numericalvalues are often essentially the observed experimental values modified byrelations which are largely empirical and are sometimes adjusted directlyto fit the observed facts.In the same paper the structures of a few intermetallic compounds arediscussed, but the number of these is too small to enable any conclusion tobe drawn as to whether the new hypothesis will permit any useful generalis-ation, and the treatment is essentially an interpretation which provides noevidence in support of the hypothesis.6. Conclusion.-From the above description it will be seen that thePauling hypothesis is at present essentially a discussion of known experi-mental data in terms of empirical assumptions for which no independentevidence is available. The papers may properly be called an interpretationof the facts, but the number of arbitrary assumptions is so great that littlehas really been explained or calculated, whilst no useful generalisationshave yet resulted. At the same time, the general method of approach tothe problem, namely by considering the electronic characteristics in theimmediate vicinity of the individual atom, is extremely suggestive and offersa useful alternative to that of the accepted theories. It seems highlyprobable that Goldschmidt’s original suggestion of the resemblance betweenthe covalent and metallic bonds is essentially correct, and the extensionof this idea in terms of orbital and resonance theory is desirable. Theoriginal hypothesis of Pauling that the number of electrons involved inbonding increases from one to between five and six per atom on passingfrom potassium to chromium seems highly probable, and seems to emphasis0429 R, E. Rundle, J . Amer. Chem. Soc., 1947, 69, 1327, 171956 GENERAL AND PHYSICAL CHEMISTRY.the part which may be played by d eIectrons in the cohesion of the earliertransition elements. The postulate of non-integral numbers of bondingelectrons per atom is purely arbitrary, but the interpretation in terms ofaverages of atoms in different states is almost certainly correct, and mayprovide a useful clue towards the understanding of the characteristics ofthe alloys of the transition metals. At the same time it should be recognisedthat this interpretation makes it probable that the average valency of themetals concerned will be different in different crystal structures. So longas one is dealing with the normal metallic structures (face-centred cube,body-centred cube, and close-packed hexagonal) it is reasonable to assumethat the average valency of a given metallic atom, in the Pauling sense,will be approximately constant. There is, however, no reason to supposethat the same average valencies will hold in completefy different structuresand the attempts made by some writers to interpret the structure of inter-mediate phases in alloys by assuming a constant series of Pauling valenciesare unconvincing and premature until the hypothesis has been more firmlyestablished. For this purpose the need at the moment is not for furtherdiscussions of structures; what is required is either the calculation ofphysical properties by fundamental methods which do not assume the valuesof the properties concerned, or alternatively the generalisation of facts toa number substantially greater than the assumptions involved.W. HUME-ROTEERY.R. C. PINK.A. R. DBBELOHDE

ISSN:0365-6217    

DOI:10.1039/AR9494600007

出版商:RSC    

年代:1949

数据来源: RSC

摘要:

CRYSTALLOGRAPHY, 1947, 1948, AND 1949.1. INTRODUCTION.THE most important event in the last three years for crystallography hasbeen the formation of the International Union of Crystallography and thedecision by this Union to publish a new journal for crystallographic papers,Acta Crystahgruphica. The International Union of Crystallography itselfwas established after the informal meeting of crystallographers from manycountries which took place in London in 1946, and the first general assemblyof the Union followed a t Harvard in 1948. The proposal that a newcrystallographic journal should be published, to replace the older Zeitschrgtfur Krista$bgruphie, was made a t the London meeting and the first numberappeared in March 1948 shortly before the Harvard Assembly.The newjournal is the property of the International Scientific Union and is, from itsfoundation, international in character ; papers may be published in itspages in English, French, German, and Russian.It must be admitted that the appearance of yet another scientific journalis not necessarily a blessing, and particular misgivings about the publicationof a journal for crystallography were felt by many who were interested inthe application of crystallographic methods in chemistry. We feared thatthe average chemical reader might lose touch with crystallographic develop-ments if these were less frequently published in the existing chemicaljournals. In fact, something rather different appears to be happening.Such a high concentration of crystallographic papers of the greatest im-portance for chemical theory has already been published in the Actu that noone interested in structural problems can afford to neglect its existence.Already there are signs that other papers, not strictly crystallographic incharacter, but bearing on chemical problems raised by crystallographicresearch, are being attracted to its pages.And certainly the concentrationof such a large proportion of crystallographic papers in one place is anenormous boon to your Reporters.The preparation of this particular report on crystallography presentsgreat problems. Owing to a variety of circumstances, no formal report oncrystallography has appeared since 1946 and there is an abnormally longinterval of three years to be covered. This interval is one in which therehas been a very great deal of new and interesting work in all branches ofthe subject, further swollen in volume by papers which describe resekhescarried out during the war.In the circumstances we have had to limitseverely our field for discussion. We have decided to attempt to combinea short account of technical developments in X-ray analysis with a surveyof structureanalyses in the inorganic field alone, leaving a survey of the organicfield as a whole to next year. We have also decided to omit this year alldescriptions of problems allied to X-ray analysis, such as crystal texture58 CRYSTALLOGRAPHY.diffuse X-ray reflections, and crystal growth. Some of these topics arepartly covered by recent reviews, e.g., of organic compounds of biochemicalinterest and of protein crystals,2 and by the Faraday Society Discussionon crystal g r o ~ t h .~ The subject of neutron diffraction is in a rather differentcategory but has also been recently re~iewed.~Mostimportant is probably R. W. James’s long awaited Vol. I1 of “ The CrystallineState,” “ The optical principles of the diffraction of X-rays,” which islikely to remain for many years to come the authoritative text on the subject.5A. J. C. Wilson has also written a short monograph on some aspects of X-rayoptics,s and A. D. Booth has given a useful summary of Fourier techniquein X-ray organic structure analy~is.~ The English translation of the text-book “ X-Ray analysis of crystals ’’ by J.M. Bijvoet, N. H. Kolkmeijer,and C. H. Macgillavry provides a very useful student’s hand-book to practicalX-ray analysis.8 R. W. G. Wyckoff has begun the labour of once againcollecting together all crystal-structure analyses. In “ Crystal Structures ”he has published the first section of the whole collection in a form to whichadditions can easily be made as new &tructures are s ~ l v e d . ~ Useful shorterreviews of crystal structures have been given by A. Tovborg Jensen onsalt hydrates,1° A. F. Wells on oxides,11 H. Bassett on basic salts,l2 and A.Bystrom on the stereochemistry of lead.13Several useful books have appeared during these three years.D. C. H.2. THE TECHNIQUE OF STRUCTURE ANALYSIS.In general terms, investigations of crystal structures can be divided intothose undertaken primarily to elucidate the chemical nature of the substance,and those in which the emphasis is on accurate atomic co-ordinates andelectron densities.Recent developments in technique have been concernedwith problems raised in both of these groups, pahicularly where the crystalstructures involve the determination of a considerable number of parameters.In the first category many structures have been published, such as thoseof penicillin,l4 strychnine,15 substituted cycZohexanes,169 l7 decaborane,181 D. Crowfoot, Ann. Reviews Biochem., 1948, 115.2 M. F. Perutz, Research, 1949, 2, 52.4 K. Lonsdale, Nature, 1949, 163, 205.6 “ The diffraction of X-rays by finite and imperfect crystals,” Methuen, 1949.7 Cambridge Univ.Press, 1948.8 Interscience Publ., Inc., New Pork, 1949.9 Interscience Publ., Inc., New York, 1948.10 “ Kristallinske Salthydrater,” Arnold Busck, Copenhagen, 1948.11 Quart. Reviews, 1948, 2, 185.12 Ibid., 1947,1, 247. .18 Arkiv .Kern&, Min., Geol., 1948,2!5, A , No. 13.14 “ The Chemistry of Penicillin,” Princeton Univ. Press, 1949, p. 310.15 C. Bokhoven, J. C. Schoone, and J. M. Bijvoet, Proc. K. Ned. Akad. Wetensch.,1 6 0. Hassel and E. W. Lund, Acta Cryst., 1949, 2, 309.17 J. M. Bijvoet, Rec. Trav. chim., 1948, 67, 777.18 D. Harker, J. S. Kasper. and C. M. Lucht, J. Amer. Chem. Soc., 1948,70,881.Trans. Faraday Soc., 1949, No. 5.Bell, 1948.1948,51,990; 1949,52,120PITT: THE TECHNIQUE OF STRUCTURE ANALYSIS.59and tourmaline,lB where the likely arrangement of chemical bonds was a tleast partly unknown beforehand. In these structures so many atoms areinvolved that trial methods of analysis seem hopeless and direct means ofderiving electron-density syntheses are needed. Attention is thus focusedon the problem of finding the phases or signs to be allotted to the measuredF values.Very large molecules are excluded from the second category becausethe experimental data are too limited to permit the accurate location ofindividual atoms, and systems containing a heavy atom are unsuitableowing to the relative insensitivity of the data to the positions of the lighteratoms. Purely organic compounds therefore form the largest group ofsuitable subjects, and in the simpler molecules both the bond-lengths andthe electron densities are of particular interest for comparison with theresults of wave-mechanical calculations.The accuracy of the experimentalresults is here of the first importance.In a great many of the published structures the Patterson synthesishas provided sufficient evidence of the positions of the molecules to deter-mine the phases approximately, from which stage the structure could berefined by Fourier methods. The complexity of the Patterson synthesis,however, increases rapidly with increasing number of atoms in the cell,and the interpretation becomes difficult unless there is a predominantlyheavy atom present. In the case of a moderately large molecule such aspenicillin, even with the help of a heavy atom, the deductions from thePatterson synthesis may not be sufficient to permit the refinement of thestructure, and it is necessary to resort to some form of trial and error, whichis often a protracted and uncertain procedure.The systematic explorationof the Patterson and Harker syntheses has been discussed by M. J. Buerger,mwho shows that Harker section syntheses perpendicular to symmetry axescan be transformed into " implication diagrams " which contain peaks a tpositions corresponding to atoms in the Fourier synthesis, plus satellitepeaks in geometrically simple relation to them, plus ambiguity peaks dueto the systematic absence of some of the coefficients needed. The methoddepends on the resolution of the Harker diagram, and the recognition andremoval of the satellite and ambiguity peaks; it becomes more and moredifficult as the complexity of the structure increases.Many machines have been developed for the approximate calculationof structure factors and Fourier syntheses in order to make possible a morerapid survey of different arrangements of the molecule.One valuablemethod of determining the structure factors corresponding to a givenprojection of the unit cell is the " Fly's Eye " which uses optical diffractionby a two-dimensional grating as an analogue of X-ray diffraction by thecrystal.21 This method was used extensively by C. W. Bunn in the workon sodium penicillin, and the structure factors for a trial projection of thelD M. J. Buerger and G.Hamburger, Arne?'. Min., 1948, 33, 532.81 See Ann. Reports, 1946, 43, 90.2o J . Appl. Phy&CS, 1946, 17, 579; A ~ t a Cryst., 1948, 1, 25960 CRYSTALLOGRAPHY.molecule could be estimated in about an hour compared with several daysto Gztlculate them on desk machines. As a result of a paper by P. J. G. deVos *2 the optical diffraction amplitude can be made to simulate more closelythe atomic scattering function, and atoms of differing atomic number canbe represented accurately in relation to one another.Available methods of calculating Fourier syntheses have up till nowbeen too slow to render the examination of extensive permutations of signsfeasible. If the effect of sign changes could be observed at once it would bepossible to approach the deduction of electron-density series (or at leasttheir refinement) by some form of systematic consideration of sign changes.This possibility has now been realised in the large-scale electronic Fouriersynthesiser described by R.Pepinsky 23 which produces a contoured electron-density map on the cathode-ray screen, the Fourier coefficients being seton potentiometers. The sign of any term may be changed by means ofa switch, the resulting change in the electron density being seen almostat once.Attempts to discover additional means of circumventing trial and errorin phase determination have achieved a measure of success, although noneof the methods described has been widely used in the solution of unknownstructures. A new approach by D. Harker and J.S. Kasper 24 has shownthat the application of the purely mathematical Schwartz and Cauchyinequalities to the observed values can yield limitations on some of thephases, due to the crystal symmetry. Defining f;'(hkZ) as ~(hkZ)~f(hkZ)where f(hLZ) is a suitable mean atomic scattering factor fiormalised to makeF(000) = 1, it is shown that in a crystal with a centre of symmetry forexample :F2(hkZ) < 9 + f 2 ( 2 h , 2k, 21)Hence if i;l^z(hkZ) >&, F(2h, 2k, 21) must be positive ;or if $(hkZ)>f, and IF(2h, 2k, 2Z)l = 9, then F(2h, 2k, 2Z) is again positive.This technique has been extended by J. Gilli~,2~ so that the signs of the40 most important terms in the P(h0Z) data for oxalic acid dihydrate couldbe deduced from the magnitudes observed.It has been of use wherePatterson and Harker methods proved insufficient in the solution of thestructure of decaborane,ls but no details are available: Owing to theassumption of a mean atomic scattering factor,' the method is probablymost reliable where all the atoms are of much the same atomic number,and it may supplement the Patterson technique which is least helpful insuch cases. E. W. Hughes 26 has pointed out that the success of this elegantmethod depends on the occurrence of a t least a few reflexions to whichmost of the atoms contribute nearly a maximum amount, i.e., _F(hkZ)>i.On an empirical basis justified by a more extensive statistical treatment byAAA22 Acta Cryst., 1948, 1, 118.23 J . Appl. Physics, 1947, 18, 601; Nature, 1948, 162, 2 2 .24 Acta Cryst.? 1948, 1, 70.25 Ibid., pp. 76, 174. 2 s Ibid., 1949, 2, 34, 37PITT : THE TECHNIQUE OF STRUCTURE ANALYSIS. 61A. J. C . WilsonF7 Hughes shows that the structure factors for tb centro-symmetric crystal composed of atoms of similar scattering powers have anapproximately normal distribution about zero if the number of atoms (N)in the unit cell is greater than ten. The R.M.S. value of 121 is l/l/x, andhence the proportion of reflexions strong enough to be of use in the equalitiesfalls as the number of atoms in the asymmetric unit increases, and forstructures of more than moderate complexity i t is unlikely that any signrelationships will be obtained. It is just for such complex structures thatsome assistance from new techniques is most needed.Another possible way of eliminating trial determination of phases arisesfrom the use of the method of steepest descents proposed by A.D. Booth.28In this is a procedure for minimising systematically a function of the observedand calculated structure factors [e.g., R =21 1 IFobs,[ - lFcalc.I 1 or R, =C (El&,. - F",lc.)2 or R, = C (log - log Icalc.)2].29 R can be representedas a set of surfaces (R = constant) in 3N-dimensional space, N being thenumber of crystallographically different atoms present. The methodminimises R, by proceeding in the direction of the normal to the initialsurface until the function no longer decreases. Having thus arrived at anew R-surface the procedure is repeated until the minimum is reached.It has been suggested (though not yet satisfactorily demonstrated) that itmay be possible to start with a random set of atomic positions and stillconverge to a solution of the structure.The general method is capable ofadaptation to take account of any partial information available about themolecule, and in particular will deal with cases where (a) the atomic positionsare approximately known, (b) the configuration of the molecule is knownbut not its position or orientation in the cell, and ( c ) the molecular shape isonly vaguely known as an approximate electron-density distribution (asmight be the case in megamolecular structures). Tentative applicationsof the method have been reported in the refinement of co-ordinates fromFourier projections in two structure^,^^,^^ and in the case of the partly-ordered C-phase of Ag-Zn, M.M. Qurashi has refined the atomic co-ordinatesand an order parameter simultane~usly.~~ Intended for use with anelectronic c o m p ~ t o r , ~ ~ the method is not very suitable for calculations ondesk machines.The concept of structure analysis as a minimisation process mentionedabove has recurred in a number of papers dealing with accurate structuredeterminations. W. Cochran 34 has shown that Fourier refinement minimises22 7; (Fobs. - FcalcJ2 and is therefore a special case of the least-squares methodhkl hkl1J27 Acta Cryst., 1948, J, 318.28 Nature, 1947, 160, 196; Proc. Roy. SOC., 1949, A, 197, 326.2% V. Vand, Nature, 1948,161, 600; 1949,163, 129.3* Idem, Ada Cryst., 1949, 2, 214.s2 Ibid., 1949, 2, 404.33 A.D. Booth, Proc. Roy. Soc., 1948, A, 195, 286.s1 G. J . Pitt, ibid., 1948, 1, 168.Acta Cryst., 1948, 4 13862 CRYSTALLOGRAPHY.of Hughes 35 which minimises 2h.uto an observation.- Fcalc.)2 where w is the weight givenThe possibility therefore arises of modifying the FourierW method by weighting the observations and minimising C 7 (Fobs. - FCalc.J2 inorder to reduce the effect of the less reliable terms. While this may beadvantageous where atomic co-ordinates are sought the Fourier seriesremains the only one for finding the electron density. It is concluded thatthe co-ordinates derived from an appropriately weighted series are some-what more accurate than those from the unweighted one, but that in reducingthe uncertainty in the atomic positions it is more important to obtain moreaccurate observed and calculated structure fact0rs.3~The atomic co-ordinates derived from Fourier syntheses are liable toerror due to : (1) experimental errors in the observed structure factors;(2) termination of the Fourier series a t a finite 8 value while the coefficientsare still appreciable; and (3) rounding-off errors in computation.A. D.Booth37 estimated the errors liable to arise from these causes, and morerecently D. W. J. Cruickshank 38 has extended his treatment and developedprocedures for correcting the systematic errors and estimating the standarddeviations of the random errors. He recommends the application ofstatistical-significance tests to the differences in bond-lengths deduced.The probability is calculated that the difference in lengths of two bondsbetween atoms whose co-ordinates have errors of known standard deviationscould be due to the random errors alone; if this probability is greater than5% the difference is not significant; if less than 1% it is significant; andbetween these limits it is possibly significant.The adoption of this proposalwould render comparisons between results in different structures much morereliable.The relative effects of the first and the third source of error on the electrondensity have been discussed by Cochran.39 . The Beevers-Lipson methodof summation (rounding-off F and F cos 2xhx to the nearest integer) is shownto be sufficiently accurate unless the structure factors are measured to anaccuracy such that their standard deviation of error is less than 2.Round-ing-off to the nearest 0.1, which is possible with the new Fourieris adequate in all cases.The effect of terminating the Fourier series while the coefficients arestill appreciable, and the effect of applying an artificial temperature factorto the coefficients to ensure the convergence of the terminated series, havebeen studied by Booth,37 Cruickshank,38 and J. M. Robertson and J. G.VVhite.41 The use of an artificial temperature factor is shown to lead toa smearing-out of detail, and the atomic positions are subject to error owingto overlapping from adjacent peaks. The omission of all terms beyond8s J .Amer. Chem. Soc., 1941, 63, 1737.86 D. W. J. Cruickshank, Acta CryskrtZ., 1949, 2, 154.38 Acta Cryst., 1948, 1, 92 ; 1949, 2, 65.$0 Ibid., 1949, 8, 131.€'roc. Roy. Soe., 1947, A , 188, 77; A , 190,482, 490; A , 193, 305,Ibid., 1948, 1, 54.4l PTOC. Roy. Soe., 1947, A, 190,329PITT : THE TECHNIQUE OF STRUCTURE ANALYSIS. 63a certain 8 value causes the superposition of a set of ripples on the electron-density diagram, tending to displace the maxima. The errors are small ifobservations are included up to the limit obtainable with copper radiation,and can be corrected satisfactorily from a dummy Fourier synthesis basedon the calculated structure factors.As yet few structures have been determined with the full accuracypossible on these considerations, but it is already clear that much newinformation will be brought to light, with respect not only to the atomicpositions and consequently their mutual configurations, but also to the electrondensity throughout the lattice.It is now certain that, with careful measure-ment of the intensities of the reflexions, the influence of the hydrogenatoms on the structure factors of an organic compound can often be demon-strated, and peaks can result in electron-density maps in positions consistentwith known lengths of bonds to hydrogen,q2 The effect is particularlywell marked in three-dimensional electron- density series such as thosecalculated for naphthalene 43 and decaborane,l* Theawell-known statementthat “ the positions of hydrogen atoms cannot be found by X-ray analysis ”must therefore be modified.Moreover, it is claimed that electron-densitymaps can be obtained with sufficient accuracy to warrant deductions beingdrawn from regions where the density is less than 9 electronl~.~; directevidence may thus be provided for various features of modern valencytheory. An example is provided by the investigation of the aminopyri-midines, where C. J. B. Clews and W. Cochran *4 find small electron-densitypeaks near the nitrogen atoms which they claim could be explained if tihydrogen atom were attached to one nitrogen atom and were interactingwith an unshared electron pair on the other, lending support to this con-ception of the hydrogen bond.The accuracy of the structure of dibenzyl has been discussed in detailby Cruick~hank,~~ and G.A. Jeffrey’s conclusions 45 about the shorteningof the central bonds are placed on a firmer basis. It is understood thatthe bond-lengths and the angles are now in good agreement with thosecalculated by the molecular-orbital method. It is perhaps instructive tonote the length reported for this central bond a t the various stages of theanalysis :(1) From two-dimensional Fourier projections . . . . -1.58 A.(2) From three-dimensional Fourier section and line syntheses 1.48 A.(3) From three-dimensional differential Fourier syntheses . 1.501 A.(4) After correction for finite-series error . . . . . . 1-510 A.The estimated standard deviation of the last result is 0.015 A.It will be seen that bond-lengths in crystal structures of this complexitycannot be considered to be of the highest accuracy unless the analyses fromO2 W.P. Binnie, J. D. Morrison, and J. M. Robertson, Nature, 1948, 162, 889.Oa S. C. Abrahaxns, J. M. Robertson, and J. G. White, Acta Cryst., 1949, 2, 233,O4 Ibid., p. 46.238.Proc. Roy. Soc., 1947, A, 188,22264 CRYSTALLOGRAPHY.which they are deduced conform to the following conditions : (1) theintensities of all reflexions a t least to 8 = 90" for copper radiation havebeen measured and corrected accurately ; (2) three-dimensional methodshave been applied to the refinement of co-ordinates ; and (3) corrections forsystematic errors have been applied, and an estimate of the random errorsis made. Of structures so far published, those of dibenzyl, thiophthen,46and 2 : 6-dichloro-4-aminopyimidine 44 alone satisfy these conditions fully.G.J. P.3. CRYSTAL CHEMISTRY.In March 1947 a very sad event occurred, the death of V. M. Goldschmidt.The framework of crystal chemistry which he established is still the frame-work within which we can describe all inorganic crystal structures. It isimpossible to survey this field, as we propose now to do, without realisingagain and again how deep and wide is Goldschmidt's infl~ence.*~Inorganic Crystal Structures.-The field, this year, is dominated by thevery remarkable series of papers published by W. H. Zachariasen. Thesecontinue, in more than one sense, Goldschmidt's own researches, his use ofsurveys to establish chemical relations and his particular interest in theuranium metals.Zachariasen's papers are concerned with the crystalchemistry of all the elements of the 5f series, from actinium to americiumand curium, and the investigations were first described in Manhattan Pro-ject Reports. The fact that the elements and $heir compounds were, inmany cases, first obtained in microgram quantities, unweighable and un-analysable by ordinary chemical methods, made it necessary to use X-raymethods not only to deduce the relative positions of the atoms in the crystalsbut also the relative numbers of different atoms present-even, in somecases, which atoms were present. Many of the identifications could bemade by finding that the crystals present belonged to known structuretypes.Others were effected through a study of compounds of relatedelements, particularly of the rare earths. But, in many cases, new individualstructures were involved, and here Zachariasen made use of certain particularcharacteristics of the phases he studied-the fact that they consisted usuallyof a heavy element of high scattering power combined with light elementsof known volume. The number of heavy atoms in a unit cell could thereforebe determined from the intensities of X-ray lines, the number of light atomsfrom the volume, and the formuh deduced could be checked against thepossible ~ a l e n c i e s . ~ ~One or two examples may perhaps best illustrate the kind of processesinvolved in Zachariasen's researches. In one experiment E.F. Westrumattempted it calcium reduction of plutonium trifluoride in a barium sulphidecrucible. The product gave powder lines characteristic of the sodiumchloride lattice, and from the relative intensities might have been either* 8 E. G. Cox, G. A. Jeffrey, and R. J. Gillot, Acta Cryst., 1949, 2, 356.*' Cf. The Goldschmidt Memorial Lecture, J. D. Bernal, 1948 (J., 1949, 2108).W. H. Zachariasen, J . Arner. Chem. Soc., 1948, 70, 2147HODGKIN : CRYSTAL CHEMISTRY. 65barium oxide or plutonium sulphide; it was shown to be the latter byfurther oxidation to plutonium dioxide, the X-ray spectrum of which wasknown. Both the existence and structure of plutonium monosulphidewere hence establi~hed.~~ In another experiment a micro-sample knownto contain chlorides of uranium was prepared by sublimation into a thin-walled glass capillary.Three zones appeared, green, reddish-brown, andblack, far enough apart for powder photographs to be taken of themseparately. The patterns showed that the green zone consisted of UCl, andthe red one of UCl,, which had been previously examined. The black zonegave a new pattern which could be indexed on the basis of a hexagonal cell,just large enough to accommodate 18 chlorine atoms, while the reflectionsmissing required the presence of three uranium atoms. Hence the blackphase was UCl,; and further details of the intensity distribution could beused to fix the arrangement of the chlorine atoms and to show that in thecrystals separate UCl, molecules were present with U-cl 2.42 A.50Apart from the great experimental ingenuity involved in Zachariasen'sstudies, the most striking feature about them is the number of compoundsinvolved.His first paper in Acta Crystallographica describes 17 new struc-ture types and lists 60 compounds belonging to them, one of his latest, thetwelfth, lists 58 compounds belonging to known structure types, and manyof the intervening papers deal with structures in neither of these lists. Itis characteristic that he has examined compounds of the elements studiedin a large number of valency states. We have, as a consequence, extremelyinteresting examples of the change of structure type with valency, whichinvolves changes in the character of the bonds present. Examples are theseries of chlorides of uranium from predominantly ionic UCl, to covalentUCI,, or the uranium silicides with silicon present as isolated atoms, chains,networks, or three-dimensional structures.A far more complete pictureof the crystal chemistry of the elements of the uranium period can be giventhan of almost any other. And the results suggest that much more intensivestudy of other systems is necessary before we can understand many of thecomplexities that appear in structure types and bond distances.TABLE I.Radii in 5f series.510 Th4+ ............ 0.95 Ac3+ ............ 1.11 La3+ ............ 1.041 Pa4+ ............ 0.91 Th3+ ............ 1.08 Ce3+ ............ 1.022 U4+ ............... 0.89 Pa3+ ............ 1.06 Pr3+ ............ 1.003 Xp*+ ............0-88 U3+ ............... 1.04 NdS+ ............ 0.995 Am4+ ............ 0.85 Pu3+ ............ 1-01 Sm3+ ............ 0.976 Am3+ ............ 1.00 Eu3+ ............ 0-974 Pu4+ ............ 0.86 Np3+ ............ 1.02 Pm3+ ............ (0.98)From the crystal structures of the dioxides and trifluorides of theelements 89-95 Zachariasen has derived the ionic radii listed in Table I49 Acta Cryst., 1949, 2, 291.5 1 Zachariasen, Physical Rev., 1948, 73, 1104.Ibid., 1948, 1, 285.REP.-VOL. XLVI. 66 CRYSTALLOGRAPHT.which may be compared with the corresponding values for elements of thelanthanide series deduced from Goldschmidt’s early researches. Thedioxides are all of the fluorite type, fluorides of the tysonite type.It is notable that in the 5f series there are two prominent valency states-he two ionic series may be described as thoron and actinon respectively-whereas the 4f elements show only one.The decrease in ionic size isparalleled in the size of the ions (X0,)+2 in uranyl, neptunyl, and plutonylcompounds. But in other valency states there are many variations incrystal radii among these elements which are difficult to explain.In his investigation Zachariasen used almost entirely powder data.I n many of the structures examined the heavy atoms so dominated theintensities of the reflections that the light atoms had to be placed largelyby packing considerations. In some cases, therefore, the interatomicdistances are not determined with high accuracy. The last three yearshave, however, seen much extended use of single-crystal measurements andFourier series to assist in placing atoms accurately in inorganic crystals.More and more complex systems have been examined-one silicon carbideis now recorded with a unit cell dimension of 219.65 A.52 At the same timedetailed studies of the electron density have been made in compounds asdifferent as magnesium oxide,53 the alloys NiA154 and Co2A1,,55 and the boronhydride, B,,H,4.18 As a consequence, the body of interatomic distancesin complex structures determined with good accuracy is growing rapidly.The details of the interpretation of interatomic distances in manyinorganic compounds are however, a t present, still a matter for considerablediscus~ion.~~ Until it comprehensive theoretical treatment of the electrondistribution in these systems can be undertaken, it it3 usual to consider,in each case, the possible operation of a variety of factors.Some of these,ionic size, co-ordination, and the number of available electrons in covalentsystems, wsre recognised by Goldschmidt. Others, such as the characterof the orbitals used in single and multiple covalent binding, have beenintroduced later. But the fact that many bonds are clearly intermediatein character makes it often necessarily difficult to account in such terms forparticular interatomic distances without an appearance of special pleading.The most important recent development in this field has been the deductionby Pauling of new series of standard covalent radii for different valencystates and the extension of their use to fractional as well as t o multiplebonds.57 This development followed from Pauling’s theory of metals andis fully treated by Dr.Hume-Rothery elsewhere (see p. 42). Here one ortwo points only will be made.5i L. S. Ramsdell, Amer. Min., 1947, 32, 64.5p N. V. Ageev and L. N. Guseva, Isvest. Akad. S.S.S.R., Otdel. Khimisch, 1949, 3.i35 A. M. B. Douglas, Nature, 1948, 162, 565.56 A. F. Wells, J., 1949, 55; T. L. Cottrell and L. E. Sutton, Chem. Reviews, 1948,5 7 J . Amer. Chem. Soc., 1947, 69, 542; Proc. Roy. SOC., 1949, A , 196, 343.R. Brill, C. Hermann, and C. C. Peters, 2. anorg. Chem., 1948, 257, 151.2, 260HODQEIN : CRYSTAL CHBMISTRY. 67Pauling’s treatment throughout is largely experimental ; it is basedon the extension of relations found in one series of compounds or elementswhere the bond type is known to predict covalent radii for other elementsor bond types.The observed change of interatomic distance with multi-plicity in benzene and graphite, where there is resonance of single and doublecarbon-carbon bonds, leads, for example, to the derivation of an empiricalequation appropriate to resonating bonds in metallic systems,where n, the bond number, is the number of electron pairs involved in abond of radius R. Thus for bonds with one electron pair resonating betweentwo bond positions, bond number n = Q, the interatomic distance is increasedby 0.18 A. from that to be expected for a single bond of the same hybridtype.Furthersuggested relations are (2) that there is a linear decrease in radius withatomic number in one period for bonds of one hybrid type and (3) a lineardecrease with d character for bonds derived from hybrid dsp orbitals. Thefirst of the three relations has already been widely applied in electron-deficient systems ; it does appear to provide an explanation, interestingeven if very approximate, of many of the interatomic distances observed.The field most affected by this treatment, that of metal chemistry,merges with that of the semi-metallic “ interstitial ” compounds, whichprovides the first group of crystal structures to be considered here. Alloysystems formed by uranium and mercury 58 or indium and gallium 59 withthe transition elements form a natural link between the two.Here wemay mention only one point concerning metallic structures, that the crystalstructure o f technetium, element 43, artificially prepared from fissionproducts, has been determined by R. C. L. Mooney.60 The lattice is hexa-gonal close-packed, similar to that of rhenium, and falls in lattice constantsinto the expected sequence with ruthenium.Compounds between the Transition Metals and the Lighter Non-Metals-Interstitial ’’ Compounds.---The hard metal-like phases formed by thetransition metals between non-metals (such as boron, carbon, nitrogen,and to some extent oxygen and silicon) have long been classified as interstitialin character, formed essentially by fitting small atoms into holes in themetallic lattice.As more of them have come to be studied it is clear thatmany of their characteristics are not consistent with this picture alone butsuggest the operation of covalent forces between the metaI and non-metallicatoms, and as the concentration of the latter increases, between neighbouringnon-metallic atoms.Uranium hydride, UH,, is a good example of the phenomena involved.It is a metal-like hydride of definite composition, very hard, and havinga crystal structure quite unrelated to that of any of the forms of uranium58 R. E. Rundle and A. S. Wilson, Acta Cryst., 1949, 2, 148.58 E. Hellner and F. Laves, 2. Naturforsch., 1947, 2a, 177.6o Ackt Cryst., 1948, 1, 161.For bond number 4, the increase is 0.36 A. and so on68 CRYSTALLOGRAPHY.metal.61 There are two types of uranium atom in the structure.Onlytwo uranium atoms are at a distance apart, 3.316 A., at which a metallicbond can be formed between them. The remaining U-U distances arelonger, 3-707 A. ; the half of this value, 1-85 A,, is nearly equal to the value1.87 A. that might be expected for a half-bond between uranium andhydrogen.62 The hydrogen atoms may thus be described as linking theuranium atoms together by fractional bonds. U, forms 12 such half-bondsto hydrogen and would have a valency of 6. UII forms four half-bonds tohydrogen and two of fractional order -0.15 to uranium atoms. Its calculatedvalency is therefore about 2.3, corresponding to resonance between bivalentand tervalent states. A similar valency is suggested for one type of uraniumatom in U,Si.63Bonds of half or two-thirds order between the metal and non-metalwould account for the observed interatomic distances in a large number oftransition metal monocarbides, mononitrides, and monoxides.Thesecharacteristically adopt the sodium chloride lattice although the arrange-ment of the atoms in the pure metals is seldom face-centred cubic. Thestructure may be determined by the tendency of the non-metal to formoctahedrally-directed bonds by the use of two hybrid sp orbitals and tworemaining p orbitals. Similar bonding can be used t o explain the morecomplex structures of cementite Fe,C or iron silicide FeSi.65The behaviour of these systems as the proportion of non-metallic atomsincreases is illustrated by two very interesting series of researches, that byR.Kiessling on borides of chromium,66 zirconium,G7 tsntalumyGs molybdenum,and tungsten,6g and that by Zachariasen on uranium ~ilicides.~~ With metalatoms in excess, the non-metal atoms are usually isolated from each otherin the structures, at the 50% composition, MB, they are arrayed in zig-zagchains and a t the ratio MB, in layers which are graphitic in form (Table 11).TABLE 11.Arrangement of non-metallic atoms in borides, carbides, and silicides.Singleatoms.M0,BTa,BW2B--U,SiFeSicf. Fe,CPairs. Chains.- FeB- CrBI MOB - WB- TaBU,Si, USi - -Cr,C* -Double Flat Puckeredchains. layers. sheets. Networks- CrB2 - CaB - Mo2B 5 Mo2B5- W2B5 W*B,-R. E.Rundle, J . Amer. Chem. Soc., 1947, 69, 1719.L. Pauling and F. J. Ewing, ibid., 1948, 'PO, 1660.W. H. Zachariasen, Acta Cryst., 1949, 2, 94.and R. A. Mcdonald, J . Amer. Chem. SOC., 1948, 70, 99.84 R. E. Rundle, ibid., 1948, 1, 180; R. E. Rundle, N. C. Baenziger, A. S. Wilson,6 5 L. Pauling and A. M. Soldate, Acta Cryst., 1948, 1, 212.66 Acta Chem. Scand., 1949, 3, 595. 6 7 Ibid., p. 90.68 Ibid., p. 603. Be Ibid., 1947, 1, 893HODGKIN : CRYSTAL CHEMISTRY. 69There are several intermediate stages represented by individual structures.The silicon atoms are in pairs in U,Si,. In Ta,B, a very interesting double-chain arrangement appears as in Fig. 1. The limits of accuracy are notsufficient to determine whether the sides of the hexagon are irregular asshown, or regular of edge 1-72 A.In the molybdenum and the tungstenE boride phases, the structure, if all possible holes are filled with boron atoms,has one set of boron atoms arranged in a flat graphitic layer and another ina puckered close-packed hexagonal sheet in which each boron atom wouldhave six neighbours, at 1.76 and 1-92 A. Actually the ideal compositionMe,B, is not reached in this phase and some of the holes must usually beempty. The final stage is a three-dimensional network of non-metal atomswith the metal atoms in the interstices. This is shown by a-USi, whichhas the structure early found for ThSi,. (Zachariasen points out thatthere might be a form of carbon having the same arrangement as the siliconatoms here.) An old example among borides is CaB,.fi97- i 8 1.72- 1-79(a) (b) (4 ( d )(a) Chain ; (b) double chain ; (c) sheet ; (d) puckered sheet.FIG.1.Types of arrangement of boron atoms found in borides.In the silicide structures the distances between silicon atoms correspondroughly to single bonds, except in p-USi, (graphitic layers) where it is shorter.In all the borides, the boron-boron distance is greater than Pauling’s latestsingle-bond length, -1.60 A., derived largely from CaB,. In CaB, each boronis surrounded by five others at 1-72 A. and Pauling assumes the bond numberis 0.6 (giving the valency 3 for boron). In the present structures the boron-boron distance varies between 1.72 and 1.91 A. in different chains and layersand seems to depend on the radii of the metallic atoms.Similar phenomena have been observed in different carbide structures,e.g., single atoms, cementite ; chains, chromium carbide Cr&, ; and layers,potassium graphite.In chromium carbide also the distance given toC-C, 1.64 A., is greater than the normal single bond distance.Metallic Sulphides, Oxydphides, and Se1enides.-Sulphide structuresshow several relations to the semi-metallic group just discussed. Again anumber of systems has been studied, illustrating the gradual change instructure type with change in the proportion of the constituent^.^^70 E.g., nickel sulphides, D. Lundqvist, Ariciv Remi, &fin., @sol., 1947, 24, no. 2170 CRYSTALLOGRAPHY.We may list first some of the sulphides of metals of the fanthanon andactinon series examined by Za~hariasen.~~ A survey of phases formedbetween cerium, thorium, uranium, and sulphur was made, and individualsulphides of many other elements were studied (cf.Table 111). Many of thephases belonged to known structure types ; others, particularly Ce2S3,Th7S12, and Ce,O,S, represent new structure determinations.TABLE 111.Structure type ... NaCl Sb2S3 Th,P, Th,SI2 PbCIa PbFCl Ce202S- Ce,S,-Ce,S, - ._. - Ce,O,S Ce .................. CeSTh .................. ThS ThzS3 - Th,Sia ThS, ThOS -- - - - - u ..................... us u2s,Np .................. - Np2S3 - - - NpOS -Pu .................. PUS - p'Zs3 - - I PU2O2SThe phase Ce,S, has the structure type found earlier for Th,P4, witheach metallic atom surrounded by eight non-metallic atcms.In the unitcell a t the composition Ce,S, there are the correct number (16) of sulphuratoms, but too few cerium atoms (log), for the available positions. Nophase change occurs as the composition is changed to Ce,S,, but a contractionof the lattice takes place and the substance becomes more metallic in ap-pearan~e.~, Th7S1, also has metallic character and a disordered crystalstructure. The thorium atoms may occupy the alternative positions, andcertain sulphur parameters must vary according to the actual thoriumpositions occupied.73There are some puzzling relations in the interatomic distances observedand also in such facts as that Am2& and Pu,S, are isostructural with Ac,S3and Ce,S,, while neptunium, thorium, and uranium sesquisulphides have adifferent structure.Zachariasen considers that all the monosulphides (cf.monoxides in the preceding group) are metallic in character, and also thesesquisulphides of the uranium group and Th,S,,. The sulphides of thecerium group seem intermediate. Whereas the radius of plutonium isonly 0.01 A. smaller than that of cerium in the ionic trifluorides it appearsto be 0.12 A. smaller in the metallic monosulphide and disilicide and 0.06 A.smaller in Ce2S3.Cerium oxysulphide, Ce,02S,74 was first identified as such by the structureanalysis of one constituent of a mixed cerium oxide-sulphide preparation.In the crystal structure, which is also shown by La,O,S and Pu20,S, eachmetal is bonded to four oxygen and three sulphur atoms; the metal-to-sulphur distances are somewhat longer, and the metal-to-oxygen distancessomewhat smaller, than the sum of the ionic radii.The arrangement ofseven groups about the metal atom is shown in Fig. 2 , where it is comparedwith the very similar plan found in zirconium oxysulphide. In the lattercompound the seven-membered group is composed of four sulphur and threeoxygen atoms, and the interatomic distances agree well with those found71 Acta Cryst., 1949, 2, 291.73 Idem, ibid., p. 288.72 W. H. Zachariasen, Acta Cryst., 1949, 2, 57.?4 Idem, ibid., p. 61HODGKM : CRYSTAL CHEMISTRY. 71in ZrO, and ZrS,.V5found in K,ZrF,-derived from a distorted octahedron.In both cases the arrangement is essentially that9FIG.2 .Seven co-ordination groups in zirconium and cerium oxysulphides.The other sulphide and selenide structures examined conform approxi-mately to one of two recognised types, with either tetrahedral or octahedralarrangements of the non-metal around the metallic atom. The structuresof the gallium sesquisulphides, selenides, and tellurides, for example, arebased on the zinc-blende lattice, but the structure is a defect structurewith the gallium atoms distributed among tthe available tetrahedral holes. 76In the ferromagnetic mineral, cubanite, CUF~,S,,~~ the arrangement is alsoone with the metal atoms surrounded tetrahedrally by sulphur atoms, butin one plane the iron-sulphur tetrahedra share edges which brings the ironatoms within 260 A.of one another. The arrangement suggests covalentbonding as in KFeS, 78 where chains of FeS,- teetrahedra sharing edgesexist (Fig. 4). The iron-to-iron distance, 2.50 A., is shorter in cubanitethan in KFeS,, 2.70 A., and may be connected with the magnetic propertiesof the material. Buerger is investigating the related iron sulphide pyrrhotiteto test this view.79Among the octahedral co-ordination group further examples, TiSe-TiSe,, and TiTe-TiTe,, have been found of the phenomenon first observedwith cobalt tellurides, of gradual change of structure type without changeof phase.80 As more metal atoms are introduced, octahedral holes in thecadmium iodide lattice are filled, to give the nickel arsenide structure. Inthe alkali thiochromites and selenochromites, the chromium and non-metalatoms form complex ionic layers of the cadmium iodide type.81 As thesizes of the alkali metals or non-metals increase the chromium atoms areforced further apart and this affects the magnetic properties of the material.The interatomic distances fit reasonably well with ionic radii but the crystalsthemselves are deep bluish-black and show metallic lustre.7 5 J.D. McCullough, L. Brewer, and L. A. Bromley, Acta Cryst., 1948, 1, 287.7 6 H. Hahn and W. Klingler, 2. anorg. Chem., 1949, 259, 135.77 M. J. Buerger, Amer. Min., 1947, 32, 415.7 8 J. U'. Boon and C. H. Macgillavry, Bee. Trav. chim., 1942,61, 910.7g Amer. Min., 1947, 32, 411. 80 P. Erlieh, 2. anorg. Chem., 1949, 260, 1.W. Rudorff, W. R.Ruston, and A. Scherhaufer, Acts Cryst., 1948,1, 19672 CRYSTALLOGRAPHY.Oxides and Metal Oxide Complexes.-Most of the oxides recently studiedinvolve octahedral co-ordination of the oxygen atoms around the metalatoms. But there are so many complexities in the distortion and methodof linking of the oxygen octahedra that it is often difficult to see the chemicalimplications of the atomic arrangements found. Even a simple oxide likenickel oxide has recently been shown to have, a t ordinary temperatures,lattice constants corresponding to a very slightly deformed sodium chloridelattice-rhombohedra1 and not cubic. The deformation vanishes aboveabout 200" and increases at low temperatures ; possibly here it is connectedwith the nickel-oxygen size ratio.82One of the most remarkable series of oxide structures is that found byA.Magneli working on molybdenum and tungsten oxides, particularlyMOO,, Mo,O,,, Mo,O,,, and Mo,O,. The dioxides, MOO, and W0,,83 havedistorted rutile structures. The metal-oxygen octahedra, MeO,, are coupledby edges to form strings, running through the crystal. Within the stringstEe molybdenum atoms are alternately 2.48 and 3-72 A. apart. The shortFIG. 3.The arrangement of linked octahedra in Mo,O,, .distance implies a covalent bond between the molybdenum or tungstenatoms; it is even shorter than the single-bond distance, 2-58 A., calculatedon Pauling's radii for the hybrid state found in metallic molybdenum.Between the strings, on the other hand, the distance between metal atomsis 3.72 A.The crystal structures of Mo,O,, and Mo,O,, 84 are built on ratherdifferent principles.In each of these, two-dimensional " boards " areformed of MO, octahedra sharing corners. These boards extend throughoutthe crystal parallel to one axis, but normal to this they extend for eightoctahedra in Mo,O, and for nine octahedra in Mo,O,,. The two octahedraa t each end of a board share edges with corresponding octahedra of otherboards, the remaining octahedra being linked by corners. Hence gaps arisein the structure (Fig. 3). A somewhat similar arrangement is shown in thevanadium oxide, V1202,, where again overlapping strings of octahedra arepresent.85 The maintenance of order in these complex systems presentsa very interesting problem.82 H.P. Rooksby, dcta Cryst., 1948, 1, 226.88 A. Magneli, Arkiv Kemi, Min., Geol., 1946, no. 24 A.84 A. Magneli, Acta Chem. Scand., 1948, 2, 501.F. Aebi, Helv. Chins. Acki;, 1948, 31, 8HODGKIN : CRYSTAL CHEMISTRY. 73The deficiency of oxygen relative to MOO, is made up in these structuresby linking octahedron edges, Another method is shown in Mo401, 86where one-quarter of the molybdenum atoms is surrounded only by a tetra-hedron of oxygen. The structure is much looser than those already men-tioned-the cell volume corresponds to 20 A.3 per oxygen as against 16.4in MOO, and nearly 19 ~ . 3 in the other oxides. In y-tungsten oxide,w18049," the arrangement of tungsten atoms is even more irregular. Andhere a short W-W distance, 2-60 A., similar to those in WO, and MOO, againappears.The oxygen atoms can be placed in an intricate way to formoctahedra linking corners and edges.With the tetragonal tungsten bronzes the ratio W : 3 0 is reached andthe tungsten oxide framework is formed of octahedra linking corners only.But according to Magneli's structure, these octahedra are joined in a verycomplex way to form strings or polygons of three, four, or five octahedra.The potassium or sodium atoms are then situated in interstices of adjacenttetragons or pentagons surrounded by twelve or fifteen oxygen atoms.ssA group, Ti,O,, exists in the recently studied non-ferro-electric bariumtitanate structure. Here the group is formed by two distorted TiO, octa-hedra sharing a face. And again the Ti-Ti distance, 2.67 A., is of the orderof magnitude of a single covalent bond length.89 It is clear that thecharacter of the ferro-electric modification depends closely on the actualsize relations and ion distribution in this form,9o In the magnetic ferriteswhich have a spinel type of structure, there are also very interesting relationsbetween cation sizes, distribution, and magnetic proper tie^.^^Several new X-ray analyses involving manganese have been carriedout.The mineral hollandite consists of a framework of linked octahedraof approximate formula MnO, enclosing barium ions in cuboid spacs~.~2y-MnO, (ram~dellite)~~ and HMnO, (groutite) 94 both crystallise in the sameform as AIHO, (diaspore), with the exception that the distortion of theoxygen octahedra due to hydrogen bonds in diaspore and groutite is absentin ramsdellite.R. L. Collins and W. Lipscomb 94 point out that there isyet another distortion present in manganite which may be found, on moredetailed study, to be present in the other structures. Four oxygen atomssurround the manganese atom in a square a t 1435-1-95 A., while two othersare further away a t 2-30 A. The arrangement is more easily understoodif the bonding is partly of the covalent dsp, type.Still stronger evidence of the existence of directed covalent bonds occurs8 e A. Magneli, Acta Chem. Scand., 1948, 2, 861.87 Idem, Arkiv Kemi, 1949, 1, 223.88 R. D. Burbank and H. T. Evans, Acta Cryst., 1948, 1, 330.88 fbid., pp. 213, 269.R. G. Rhodes, Acta Cryst., 1949, 2, 416.E.J. W. Verwey, P. W. Haayman, and E. L. Heilmann, PhiZipa Tech. Rev.,1947, 9, 185; E. J. W. Verwey, F. de Boer, and J. H, van Santen, J . Chem. Physics,1948,16, 1091.O2 A. Bystrom and A. M, Bystrom, Nature, 1949, 164, 1128.Og A. M. Bystrom, Acta Chem. Scand., 1949, 3, 163.g4 R. L. Collins and W. Lipscomb, Acta Cryst., 1949, 2, 10474 CRYSTALLOGCRAPHX.in certain uranium oxides and mixed UO,, U30,,96 uranyl fluoride(UO,F,), and lithium, sodium, potassium, strontium, and calcium uranyloxides. In all these, hexagonal or pseudo-hexagonal layers occur in whichuranium atoms are surrounded by six oxygen atoms at about 2.29 A. inflat octahedra and by two oxygen atoms forming a linear group normal tothe layer. In UO, these linear groups are linked to form continuous chains-U-0-U-0-. In all the other compounds a definite group UO, is formedwith U-0 about 1.91 A.This distance is nearly that required for a doublebond on Pauling’s radii, suggesting the group is O=U=O ; the larger distance,2.29 A., might correspond to a one-third bond, but presumably here thevalency is partly ionic. In the mixed oxides the metal ions pack betweenthe layers, binding them together. In uranyl fluoride, fluorine replacesalternate oxygen atoms in the octahedra, and the layers are loosely stackedwith some disorder. A uranyl group with the same dimensions is alsofound in barium uranyl oxide, Ba(U0,)02, but here the layer has tetragonalsymmetry and the uranium atom has four neighbours, a t 2-12 and 2.22 A,,other than those of the uranylHades.--Some of the clearest examples of transition from ionic- tocovalent-structure types are provided by new halide structures.To begin with, aluminium trichloride has, after all, an ionic crystalstructure.98 The chlorine atoms are arranged in slightly deformed cubicclose packing as originally proposed, but the aluminium atoms are singlyin one set of octahedral holes, not in the tetrahedral holes, as required forthe structure, A12C1,.All the crystal structures of copper halides and mixed halides, cupricand cuprous, have structures characteristic of covailent binding.In bothCuC1,gQ and CuBr2lo0 flat chains appear, as in Fig. 4 (i) below, of the PdCI, type.I n CsCuC13,10L the co-ordination of the chlorine atoms round the copper isalso planar but the chain is spiral in form.Formally it could be representedas in Fig. 4 (iia). A. F. Wells compares the chain (i) to its tetrahedralanalogue in SiS,-FeS,- is another example-and (ii) to the silicate SiO,chain in diopside. A closer tetrahedral analogy is with the CuCf, chain inthe cuprous compound K2CuCI, where the bonds at the chlorine atoms arebent, not nearly linear as in the silicates.lo2In all the cupric halides, including also the hydroxy-chloride and-bromide, Cu,Cl(OH), lo3 and Cu2Br(OH),,1M it is noticeable that, in addition95 W. H. Zachariasen, Acta Cryst., 1948, 1, 281.96 Cf. F. Grenwald, Nature, 1948, 162, 70.97 S. Samson and L. G. Sillen, Arkiv Kemi, &fin., Geol., 1948, 25, no.21.s* J. A. A. Ketelaar, C. H. Macgillavry, and P. A. Renes, Bee. Truv. chim., 1947,88, 501.A. F. Wells, J., 1947, 1670.loo L. Helmholz, J . Amer. Chem. Soc., 1947, 09, 886.lol A. F. Wells, J., 1947, 1662.lo2 C. Brink and C. H. Macgillavry, Actu Cryst., 1949, $3, 158.lo8 A. F. Wells, ibid., p. 175.lo4 F. Aebi, Helv. Chim. Ada, 1948, 31, 369IXODGKIN : CRYSTAL CHEMISTRY. 75to the four strong bonds of the square dsp, type, the copper atom is a tintermediate distances, corresponding to bonds of very low order, awayfrom two other atoms, halogen or hydroxyl, which complete a distortedoctahedron. Wells suggests that this arrangement may be connected withthe presence of an odd electron, with some bonding power, in one of thep orbitals in the cupric valency state.The situation may be comparedwith that of manganese in mangsnite, but here the difference between thebond lengths is rather greater ; in CuCl,, for exsmple, Cu-4C12.3 A., Cu-2Cl2.95 A.An interesting example of the distinction between planar and octahedraltypes comes from the study of Pt(NH,),Br,,Pt(NH,)2Br4.105 Here planarand octahedral groups succeed one another in a chain in the crystal. Inthe double salt 2NH,C1,FeCl3,H2O an octahedral ion [FeC1,,H,0]2- isformed.lo6'' (ia)(ila) (iib)FIG. 4.Diagram of chain arra.ngements i i ~ : (ia) cu.pric chloride, (ib) potassium thioferrite,(iia) cmsium cuprichloride, and (iib) potassium cuprochloride.With the halides of the uranium metals we can trace the effects ofboth change of halogen and change of valency.The number of compoundsexamined is too great to permit their individual mention; we can give onlythe types of structure found in each valency state.Here it is noticeable that the co-ordination number of theheavy metal changes from 11 in UF, to 9 in UCl, and UBr,, and to 8 in uI,.107 The crystal structures of the first three are of ionic types; UF,and thirteen others have the LaF, structure, while eighteen compoundsare listed with the UC1, structure.108 UI,, like PuBr, and many otherbromides and iodides, has a layer structure.(a) AX,.lo5 C . Brosset, Arkiv Kemi, Min., GeoE., 1948, 25, no. 19.lo6 I. Lindqvist, ibid., 1947, 24, A , no. 1.lo' W. H. Zachariasen, Ada Cryst., 1949, 2, 388.lo8 Idem, J .Cliem. Phgsics, 1948, 16, 254; Acta Cryst., 1948,1, 26576 CRYSTALLOGRAPHY.(b) AX,. The fluorides belong to a complex monoclinic structure typerepresented by ZrF,, not fully worked out. UCl, and ThC1, have interestingstructures; log each metal atom is surrounded by four near neighbours ina flat tetrahedron, with U-4Cl 2.46 A., and four other neighbours, withU-4C1 3.09 A. The compounds are at least partly covalent and sublimea t high temperatures.Each uranium atom is here bondedto nine fluorine atoms a t a mean distance 2.31 A. The uranium atoms areequivalent in the structure and presumably there is resonance between thevalency states 4 and 5. Correlated with this is the black colour of thecrystals. The same arrangement is shown by NaTh,Fg, where the sodiumatoms fit into four or the six possible holes in the U2F9 structure.l1°Uranium pentafluoride crystallises in two different structures,cr-UF, and p-UF,.lll In the first, each uranium atom is surrounded by sixfluorine atoms in an octahedron, and the octahedra are linked by oppositecorners in chains (cf.T12AIF5). Zachariasen considers that the U-F bondshere are predominantly ionic, but the forces between adjacent chains mustbe largely of van der Waals character. In P-UF, each uranium atom isbonded to seven fluorine atoms, four of the seven corners being shared withadjacent polyhedra. The U-F distances are very similar in the two struc-tures, those in p-UF5 being very slightly longer.At the stage AX,, a definite molecule uc1, is formed.50Each uranium atom is surrounded by six chlorine atoms in a regular octa-hedron a t a distance U-C1 2.42 A.From this the single covalent radius ofsexivalent uranium may be calculated as 1.43 A., in good agreement (toogood for the limits of error involved !) with Pauling’s value of 1-42 A.Among mixed halides some ordered structures exist such as Cs2PuC1,,ll2where the czesium ions are in 12-co-ordination positions and the plutoniumin 6-co-ordination. However, there is a very large number of disorderedphases in which, for example, alkali or alkaline-earth ions occupy at randomthe same positions in the crystal as the heavy-metal ions. Examples arecr-K,ThF, or cr-KLaF, which both have the fluorite structure, or a seriesMThF, with the lanthanum trifluoride arrangement, where M is any alkalineearth.Phenomena of this kind we have become most accustomed to in thenext group, the silicates.Silicates and Silicones.-The silicates have continued to provide us withgood problems both in chemical organisation and in structure analysis.We may begin with the type of silicates usually treated last, frameworkstructures, which happen to adopt some of the less complex crystal structures.Three of these, eukryptite, LiA1Si0,,l13 nepheline, (NaK)MSiO,, 114 and(c) AX,., is represented by U2F9.(d) AX,.( e ) AX,.log R. C. L. Mooney, Acta Cryst., 1949, 2, 189.110 W. H. Zachariasen, J. Chem. Physics, 1948,16, 425; Acta Crystall., 1949, 2, 390.ll1 Idem, ibid., p. 296.l13 H. G. F. Winkler, ibid., p.27.11* M. J. Buerger, G. E. Klein, and G. Hamburger, Amer. Min,., 1947, 32, 197.Idem, ibid., 1948, 1, 268HODGKIN : CRYSTAL CHEMISTRY. 77kalsilite, KAlSiOq,l15 have been studied and their close relation to oneanother established. All three are based essentially on silicon dioxidelattices suitably distorted to permit the entry of extra atoms. That ofLiAlSiO, is the @(high temperature)-quartz lattice with aluminium andsilicon alternately at the positions of silicon in @-quartz, and the lithiumions in channels in the structure. As H. G. F. Winkler points out, largerholes can be formed more easily in a tridymite lattice which is 15.5% lessdense than in @-quartz, and this has now been established in both nephelineand kalsilite, which accommodate sodium and potassium ions.In all theselattices the Si-0-A1 bonds are bent at some, a t least, of the oxygen atoms.The angle is 145.5” in LiAlSiO,, nearly tetrahedral in parts of kalsilite, andstraight in others. In nepheline the distortion produces two sizes of holesand this suggested to the investigators that potassium as well as sodiumwas present-a fact verified subsequently by chemical analysis.The structure of tourmaline, one of the outstanding problems in thisfield, has been put forward by M. J. Buerger and G. Hamburger.llG Herethe formula may be given as approximately g iB313Jsi6027(0H)*; inorder to assist the X-ray analysis use was made of tourmalines of ratherdifferent composition from this with Mg replaced by Fe, and implicationfunctions derived from Patterson syntheses were employed. The silicon-oxygen tetrahedra were found to be linked in rings, Si,O,,, with one set ofoxygen atoms pointed down from the plane of the ring.These form part ofa system of linked oxygen octahedra surrounding magnesium ions as inbrucite. The units formed are similar to the “Mg kaolin’’ in Aruja’sstructure for chrysotile ; they are cemented together by aluminium, boron,and sodium ions, the boron in a plane triangular co-ordination.A solution for another major silicate problem, the structure of epidote,has been given by T. Ito.l17 The most interesting feature here is theproposed linking of the silicon-oxygen tetrahedra into bands of formulaSi,O,, or rather AlSi,O,. Somewhat similar bands occur in eudidymite,HNaBeSi308,11s and in a slightly different version in epididymite.Herethe main Si,O, bands are linked together with a sodium ion between themin octahedral co-ordination, forming sheets, NaSi,O,. The beryllium andhydroxyl ions in eudidymite are linked into the sheets so that the mainforces between them are of van der Waals character and the crystals easilycleave.In these three analyses the data are too limited for the atomic positionsin such complex crystals to be precisely fixed, though Fourier methods havepartly assisted in finding them. However, one of the most interestingdevelopments in this field is the further application of electron-densitycalculations to structures previously solved. A full three-dimensionalanalysis of sanidinised orthoclase has now been carried out, for example,to test the postulate that heat treatment of orthoclase resulted in the random115 G.F. Claringbull and F. A. Bannister, Acta Cryst., 1948, 1, 42.116 Amer. Min., 1948, 33, 532. 117 Ibid., 1947, 32, 532. 118 Ibid., p. 44278 ORYSTALLOGIRAPHY.distribution of silicon and aluminium in the framework. The new analysis 119established that the " Si "-0 distances in different tetrahedra were thesame, mean 1.642 A., and that the aluminium was accordingly randomlydistributed. However, it became clear in the analysis that the accuracyof the earlier work, which suggested differences in the tetrahedra in un-treated orthoclase, was insufficient to prove the point.Very interesting differences in silicon-oxygen bond distances and anglesappear in the Fourier projection calculated for Bolivian crocidolite, a fibrousasbestos-like variety of amphibole.f2* Here most of the individual atomswere observed resolved in projection by a process of subtracting, one afteranother, the contribution of atoms whose position could be fixed.TheFIG. 8.(a) ' ' Octumethylspirof 5 : 5]pentasiloxune. "crocidolite.(b) Silicate chain in Bolivianover-a11 accuracy of the analysis is not high but good enough to establishthe main character and distortion of the structure. The interatomicdistances within the double silicon-oxygen chain, much altered from the idealform, are shown in Fig. 5b. The metal ions lie in bands between the chains,and from the different heights of the electron-density peaks it is possibleto work out a scheme of distribution between them of the different metal ionspresent, K, Na, Ca, Mg, Al, and Pe.This distribution is a compromisebetween entropy considerations leading to random distribution and energyconsiderations which require unequal distribution in holes of differingco-ordination number.A silicate structure containing small finite groups is afwillite,121 in whichthe arrangement of the oxygen atoms strongly indicates the presence of119 W. F. Cole, H. Sorum, and 0. Kennard, Acta Cryst., 1949, 2, 280.120 E. J. W. Whittaker, ibid., p. 312.lel H. D. Megaw, ibid., p. 419HODGKM : URYSTAL CHEMISTRY. 79hydroxyl groups linked to the silicon atoms. Accordingly, one might writethe formula Ca(OH),,Ca*Si(OH),O,.In lawsonite, CaAI,(Si,O,)( 0H)2,€€20,according to F. E. Wickman, the more usual arrangement with hydroxylattached to aluminium appears, the silicon atoms being present in Si,O,groups.122It is very interesting to be able to compare these silicate structures withthat of ‘‘ octamethylspiro[5 : Eilpentasiloxane ” (I), measured by W. L./SiMe2*O\ / O*SiMe2\0, ,Six .O\SiMe2*O/ \O*SiMe2/ (1.1Roth and D. Harker.123 Here the silicon-oxygen rings are similar to thosefound in the mineral benitoite, though the physical properties of the spiro-siloxane are very different; it is volatile and crystallises from toluene.Calculations of the electron density in three dimensions established thegeneral shape of the molecule shown in Fig. 5a.Within the limits of experi-mental error the Si-0 bond, 1.64 A. long, is of the same order as that foundin the silicates, a distance much shorter than the sum of the covalent radii,1-83 A. Pauling considers this bond to be 50% ionic and 60% covalent;certainly the Si-0-Si bond angle, 130°, as in many silicate structures seemsintermediate in character. On the other hand, the methyl groups areattached to silicon a t the tetrahedral angle, and the Si-C distance, 1.88 A,,is only slightly smaller than the covalent-bond length 1.94 A. From theelectron density found, the whole SiMe, group appears free to oscillate, as ina ball and socket joint, movement to which the ionic undirected character ofthe Si-0 bond might contribute.Phosphates, Arsenates, and Mo1ybdates.-Phosphate and arsenate crystalstructures have an obvious relation to silicate structures except that a greaternumber of orthophosphate structures have been studied.New analysesare those of phosphates of the rare earths,12, barium, and strontium; 125bismuth arsenate has also been investigated.126 The hydrated ferricphosphates and arsenat es , Fe, (PO,), , 8H20 and Fe,( A s O ~ ) ~ ,8H20 , havecrystal structures in which there appears a group of four water moleculesarranged in a tetrahedron.12, These form part of the oxygen-atom octa-hedra surrounding the iron atoms, which are partly linked through phosphorusor arsenic and partly through water.The most interesting phosphate structure determined is probablyammonium tetrametaphosphat e , NH,PO, or rat her (NH ,) ,P,O 16.l2 Here,as in calcium metaphosphate, four PO, tetrahedra are linked in a ratherflat ring. (These arethe only inorganic metaphosphates so far analysed in detail; nothing com-Within the ring, P-0 is 1-62 A . ; outside it, 1.46 A.122 Arkiv Remi, Min., Ceol., 1948, 25, A , no. 2.lea Acta Cryst., 1948, 1, 34.lZ* R. C. L. Mooney, J . Chem. Physics, 1948, 16, 1003.125 W. H. Zachariasen, Acta Cryst., 1948, 1, 263.126 R. C. L. Mooney, ibid., p. 163.128 C. Romers, J. A. A. Ketelaar, and C. H. Macgillavry, ibid., p. 960.lZ7 T. Ito, Nature, 1949, 164, 44980 aRYSTALL00RAPHY.parable with the biochemically important trimetaphosphates has yet beenso examined.) The structure may be compared with that of the third formof phosphoric oxide where six PO, tetrahedra form a ring and these arefurther linked in sheets.129One of the most complex condensed acid structures is shown in theammonium and potassium molybdotell~rates,1~0 where the molybdenumatoms are arranged in a hexagon around the tellurium atoms, as in thestructure suggested by J.S. Anderson. The oxygen atoms in layersabove and below the hexagon form octahedra about both tellurium andmolybdenum. For the Mo-0 bond length, the best value is probably1.83 A. from the re-examined crystal structure, Ag2M004. Here the Ag-0distance, 2.42 A., is not as short as was expected from the bright yellowcolour of the compound.f31Oxy-acids and Acid Salts.-The crystal structures of the commoninorganic acids have so far not been fully examined, owing to experimentaldi6culties.A. F. Wells and M. Bailey have pointed out that they shouldprovide examples of hydrogen-bond systems which differ geometricallyaccording to the relative number of hydrogen and oxygen atoms present. 132Four main groups can be distinguished on their hydrogen : oxygen ratio :(a) <1 : 2, HNO,, HIO,, HCO,' ion; ( b ) 1 : 2, H2S0,, H,P04' ion; (c) from1 : 2 to 1 : 1, H,SeO,; and (d) 1 : 1, H,BO,, H,TeO,. The last group iswell known ; the arrangement found, with each oxygen atom distant -2.75 A.from two others, is one which is characteristic of the presence of OH groupsin many organic structures. In each of the other three groups, shorterinter-oxygen distances have now been found, one of the oxygen atoms atleast making only one such contact.SeIenious acid (group c) necessarily has an intermediate character ; theSeO, groups are arranged in double layers, and the oxygen atoms, linked a tshort distances, 2.60 and 2.56 A.as shown in Fig. 6, must differ from oneanother. It is tempting to write hydrogen at the end of the two longSe-0 bonds, 1.76 and 1.75 A., and to see these as OH groups each makingcontact with a third essentially Sex0 group, which is at the receiving endof two hydrogen bonds.In the type structure for group (a), the HCO,' ion chain system, found insodium hydrogen carbonate, the X-ray analysis suggests that the hydrogenatom is mid-way between two oxygen atoms. Wells 133 points out that itis possible to see also in the linking of HIO, groups in iodic acid a singlehydrogen-bonded chain system, provided that it is recognised that othershort oxygen-oxygen contacts in the crystal are due to the weak additionalattractive forces between iodine and oxygen.Similar chains appear in thecrystal structure of nitric acid.ls4 However, in both these last structures,12* C. H. Macgillavry, H. C. J. de Decker, and C. M. Nijland, Nature, 1949,164,448.130 H. T. Evans, J . Amer. Chem. Soc., 1948, 'SO, 1291.J. Donohue and W. Shand, ibid., 1947, 69, 222.13* J., 1949, 1282.134 M. V. Luzatti, Compt. rend., 1949, 229, 1349.133 Acta Cryst., 1949, 2, 129HODGKIN : CRYSTAL CHEMISTRY. 81the oxygen atoms in the chain are not symmetrically arranged.In thepyramidal 10, group, one 1-0 bond is longer than the others,135 and oneN-0 bond is longer in the planar NO, group, suggesting definite I-OH0FIG. 6.Diagram to illustrate arrangement of hydrogen bonds in (a) carbonate-bicarbonateion, (b) nitric acid, ( c ) iodic acid. and (d) selen,ious acid.and N-OH bonds respectively. More detailed information about boththese structures is needed to be sure of these points. The nitric acid crystalstructure particularly is very complex and affected by disorder in thecrystals. The outline presented by M. V. Luzatti is clearly reasonable;the flat molecules are packed in layers, and within each layer held in parallellS5 M. T. Rogers and L. Helmholtz, J . Amer. Chem. Xoc., 1941, 63, 28282 CRYSTALLOGRAPHY.chains by the hydrogen-bond system; but there are details of the solutionwhich call for further discussion.By far the most accurate X-ray analysis in this field is that of trona,Na2C0,,NaHC0,,2H,0 where three-dimensional electron-density serieshave been calculated and the bond lengths may be accurate to -j=O.Ol--0.02 A .~ ~ ~ Here again a similar system appears. Two planar CO,” groupsare linked by a short hydrogen bridge (2.53 A . ) ; and here crystallo-graphically the hydrogen atom should be placed midway between them at acentre of symmetry, a situation also found in potassium hydrogen phenyl-acetate and p-hydroxybenzoate, 137 However, the true relation of thehydrogen atom to the centre of symmetry may be either time average orstatistical. It is noticeable that a ridge of electron density above the l eper A . ~ runs along the line of the hydrogen bond in projection.Also thelongest of the three C-0 links is directed towards the hydrogen bond.0 0(&@+$? (6)N0 0 >- yo (e)C”3 0FIU. 7.Interatomic distances in (a) nitroniunz ion, (b) nitrogen dioxide, ( c ) dinitrogentetroxide, (d) dinitrososulphite ion, and (e) dimethylnitramine.It may be noted that the bond lengths in the CO, group in trona are agood deal shorter than in calcite (1.31 A.). No accurate figure for thisdistance can be gained from the other carbonate structure lately studied,basic bismuth carbonate, where the carbonate groups have a disorderedarrangement packed between BiO layers. 138Some Structures containing Nitrogen.-Several long-standing problemsof nitrogen chemistry have been solved by recent X-ray analysis, only toraise new questions of the interpretation of interatomic distances withinthe systems studied.These interatomic distances are shown, with othersrecently found, in Fig. 7.The new single-bond distances for N-N, 1-42 A., and N-0, 1.45 A.,13@ C. J. Brown, H. S. Peiser, and A. Turner-Jones, d c t a Cryst., 1949, 2, 167.13’ J. Speakman, Nature, 1948, 162, 698.13* A. Lagercranz and L. G. Sillen, Arkiv K e m i , Mim., CeoE., 1948, %, no. 20H0I)GB;IN : CRYSTAL CHEMISTRY. 83observed in hydrazinium dichloride 139 and hydroxylammonium chlorideand bromide,140 are shorter than might be expected from measurementson gaseous hydrazine and hydrogen peroxide.While the N-0 distancemay be modified by the difference in the electronegativity of the twoelements, this would not account for the shortening of the N-N distance.The two crystal structures are closely related. In each, four chlorine atomslie at distances about 3.1-3.2 A. from the nitrogen atom, one along theline joining N-N or N-0, the others at positions making angles of about100” with this line. These positions suggest an orientation of the hydrogenatoms attached to nitrogen which is trans or staggered in the hydrazinium ion.Intermediate bond lengths for N-0, 1-35 A., corresponding to a calculatedbond order about 1.2, are found in potassium dinitros~sulphite.~~~ Theseare similar in length to the length N-0 found in trimethylamine oxide,1.36 A., from electron diffraction,142 and suggest the ion could be formulatedhN-0-approximately O~S--N+’’ .The S-X link is 1.63 A. long, close to\O-single bond in character ; it is markedly longer than that (1.57 A.) in sulphamicacid. Probably the S-0 distances in these compounds, 1-43-1.44 A., might betaken as a standard S=O distance in syst3ms involving d orbitals. TheN-N distance is also double bond in character. It may be compared withthe distances found in dimeth~1nitrarnine.l~~ The planar character of bothmolecules supports the view that the wave function in each case involvessp, hybridisation.In nitronium perchlorate, the linear character of the ion is establishedand indicates a formulation O=-U=0.144 The N-0 distance is not accuratelydetermined yet but seems clearly shorter than that found in gaseous nitrogend i 0 ~ i d e .l ~ ~ The most interesting structure in this group is that of di-nitrogen tetroxide. m The crystal structure has been re-investigated bysingle crystal and Fourier methods and, while the atomic arrangement isclosely similar to that given originally by Hendricks, the interatomicdistances are quite unexpected. The long distance, N-N, 1-64 A,, wouldcorrespond to something of the order of a half-bond in length. It suggeststhat the nitrogen dioxide molecules remain virtually unchanged in the solidcompared with the gas, with only a weak force of attraction between them.Two azides have been investigated, cuprous azide 14’ and strontiuma ~ i d e , ~ ~ ~ the latter by three-dimensional Fourier methods.In both, thei-J. Donohue and W. M. Lipscomb, J . Chem. Physics, 1947,15, 115.14* B. Jerslev, Acta Cryst., 1948, 1, 21.141 E. G. COX, G. A. Jeffrey, and H. P. Stadler, Nature, 1948,162, 770; J., 1949, 1783.Ire M. W. Lister and L. E. Sutton, Trans. Faraclay Xoc., 1939, 35, 495.144 E. G. Cox, G. A. Jeffrey, and M. R. Truter, ibid., 1948, 162, 259.145 S. Claesson, J. Donohue, and V. Schomaker, J. Chem. Physics, 1948, 16, 207.lr6 J. S. Broadley and J. M. Robertson, Nature, 1949, 164, 915.lr7 H. Wilsdorf, Acta Cryst., 1948, 1, 115.14* F. J. Llewellyn and F. E. Whitmore, J., 1947, 881.W. Costain and E. G. Cox, Nature, 1947, 160, 82684 CRYSTALLOGRAPHY.azide group is symmetrical and linear; the N-N distance in strontiumazide, 1.12 A,, agrees with that in similar structures.These come close tothe distance in nitrogen itself and complete the range of N-N bondsexamined from 1.64 A. downwards. It is clear that N-0 bonds tend to beshorter than N-N for comparable bond number, particularly in the systemsinvolving resonance.Boron Hydrides.-Wi th the boron hydrides and particularly decaboranewe return, as in the first section of this Report, to an electron-deficientsystem. But the system here is one which, in its molecular character, formsa natural link with many organic structures.The first, a simple one,is that of sodium borohydride, which is shown by A. M. Soldate to consistof Na” and BH,- i0ns.14~ The powder data employed were insufficientto place the hydrogen atoms; the crystal symmetry suggests a tetrahedralarfangement, and the space is sufficient to allow oscillation or even possiblyrotation of the tetrahedra.Two crystal structures have been determined.FIG.8.Proposed arrangement of atoms in (a) decaborane, (b) diborane.Decaborane, on the other hand, proves to have an utterfy unexpectedatomic arrangement, found largely through a new method of phase deter-mination, combined with the rigours of three-dimensional electron-densitysynthesis.ls Some confirmation that the atomic positions proposed are,at any rate, one solution of the diffraction problem, is provided by the factthat they also fit the electron-diffraction data. The molecular structure,shown in Fig. Sa, is a slightly modified version of that already published,from which it differs principally in the position of certain of the hydrogenatoms.* For comparison, the latest inter-atomic distances suggested fordiborane are given in Fig. Sb.150The interatomic distances found in decaborane show relations both withthose m diborane and with those in metallic borides. With the exception of14* J . Amer. Chem. Xoc,, 1947, 69, 987.150 B. V. Nekrasov and V. V. Shtutser, J . Gen. Chem., Russia, 1948, 18, 832.* I am greatly indebted to the authors for this information from a. paper now inthe pressHODGEM : CRYSTAL CHEMISTRY. 85the long B-B distance of 2-01 A., all the B-I3 distances are equal, within thelimits of experimental error, to 1 . 7 6 ~ . (cf. W2B5 and CaB,). The B-Hdistances are less precisely fixed ; ten of the hydrogen atoms are attached toonly one boron atom; four lie in bridge positions attached to two boronatoms, as in the structure shown for diborane. Bond numbers may beassigned to keep the boron atoms tervalent and hydrogen atoms univalent,the preferred arrangement being one in which the majority of the boronatoms form five bonds each of number -0-4 to boron and hydrogen andone to hydrogen of number 1.0. As in the metallic borides and otherelectron-deficient systems, the bonds have no longer the directional characterascribed to normal covalent bonds. However, it must be admitted that, inspite of these relations, the theoretical interpretation of the decaboranestructure is quite obscure, and further details of its analysis are awaited withgreat interest.Clathrate Compounds.-There is one group of compounds, clathratecompounds, which cannot happily be grouped as either organic or inorganicsince both kinds of molecule occur together in one crystal in the examplesrecently s t ~ d i e d . 1 ~ ~ The first type, found by H, M. Powell and D. E. Palin,152was discussed shortly in 1946. Here quinol molecules form a hydrogen-bonded framework in the crystal inside which different molecules may betrapped. New experiments show that the framework may be somewhat dis-torted to admit longer molecules than the sulphur dioxide first observed ; thelimit is reached at methyl cyanide.153 The latest trapped molecules includethe rare gases argon and krypton, the presence of which can be establishedfrom electron-density projections. Since the cavities in which they lie are7.5 A. across, only van der Waals forces occur between these atoms and theenclosing framework.In a second type of clathrate compound, the framework is inorganic,Ni(CN),NH,, and the trapped molecules organic, e.g., benzene or thiophen.154The nickel atoms and cyanogen groups form sheets similar to a single layerof the Prussian-blue structure. From these, ammonia groups project,giving the nickel atoms alternately planar and octahedral co-ordination.Between the layers and their projecting groups, there is too much space,and crystallisation cannot proceed unless suitably sized solvent moleculesare present and can be trapped and fitted into the interval. There must bemany other compounds of this kind to be found in purely organic systems.D. C. H.In conclusion we thank Miss J. Broomhead, A. Addamiano, and D.Sayre for help in the preparation of this Report.DOROTHY CROWFOOT HODCIKM,G. J. PITT.1 5 1 I€. M. Powell, J., 1948, 61.154 H. M. Powell and J. H. Raper, Nature, 1949, 188, 566.153 Ibid., p. 571. lS3 Ibid., p. 815

ISSN:0365-6217    

DOI:10.1039/AR9494600057

出版商:RSC    

年代:1949

数据来源: RSC

摘要:

INORGANIC CHEMISTRY.THAT interest in inorganic chemistry is sustained and indeed is increasing isevident from the extent and variety of the contributions covered by thefollowing report. Again the Reporters have been concerned to present asbalanced a picture as the space a t their disposal allows of those topics whichhave excited curiosity.The first volume of the FIAT Review of German Science (1939-46),Inorganic Chemistry, was the only one available to the Reporters last yearand a considerable amount of material was drawn from it. The scope of theremaining five volumes which have now been issued precludes our drawingmuch from them this year. The work covers the whole field from biblio-graphy to instrumentation, is well indexed, and is graced by main tablesof contents in each volume in English as well as German.The recommence-ment of issues of the 8th edition of Gmelin’s “ Handbuch ” is welcomed,Selenium (B), Antimony (B), and Platinum-group metals (ruthenium,rhodium, palladium) having so far been issued.to one who laid a cornerstone of modern inorganic chemistry. EspeciallyGoldschmidt will be remembered for showing the three main considerationsgoverning the forms of co-ordination adopted by a crystal structure, namely,the relative numbers, the ratio of radii, and the polarisability of its ions.was discussed a t the Amsterdam meeting ofthe I.U.C. in September, 1919, and the names of the elements and of theI.U.C. itself were considered.The practice of placing the superscript representing the mass numberof an isotope after the symbol of the element is officially frownedupon. All but the purists will be thankful that the redefinition of the litreas a cubic decimetre will now permit the identity 1 ml.= 1 C.C. and allowsome of us to revert to our natural use of the latter unit.That the discovery and application of nuclear fission has providedstrong, almost overwhelming, impetus to inorganic chemistry is now acommonplace. Nevertheless, the evidence of its truth in the shape ofnumerous papers poses a problem in these Reports; for there is much thatis of a purely physical nature which is, however, of vital interest to chemistsusing, or measuring, isotopes. It seemed best to confine attention here to :(a) preparation or enrichment of isotopes in a particular chemical state,( b ) tracer work to elucidate an inorganic problem, (c) chemical identificationof products of a nuclear reaction, (d) determination of natural isotope abund-ances leading to atomic weight values. Facts about individual isotopescoming under the above headings will be dealt with as the element occursin the Periodic Table.A moving and just tribute is paid in the Goldschmidt Memorial LectureInorganic nomenclatureJ.D. Bernal, J., 1949, 2108. Chem. Eng. News, 1949, 27, 2996DODD AND ROBINSON. 87Rlention may be made of a number of articles and reviews : H. J.EmelBus,4 on recent advances in radiochemistry, fission products, the4n + 1 radioactive series, the actinons, material largely drawn from de-classified reports : J. V.Dunworth,5 w. G. Morley,6 and R. Spence,? re-spectively, on the operational characteristics of the Harwell piles, productionof radio-isotopes, and chemistry of a.tomic energy: the abundance ofelements and isotopes in relation to the origin * of the chemical elementsand to nuclear structure9 (the empirical approach). G. T. Seaborg andI. Perlman 10 have tabulated all known isotopes together with abundancesand references to all original papers. H. E. Suess l1 arrives at a value of4-5 x lo9 yrs. for the age of the elements on the basis of (corrected)abundance rules. H, Thode l2 has reviewed isotope abundance in Naturewith special reference to variations in relative abundances of isotopes of aparticular element depending on the source.(Variations in boron havealready been reported. Variations in sulphur have been recently discovered-see p. 106.) J. Mattauch 13 and others l4 have reviewed isotope separation.A further review on radio-isotopes as tracers has been given by P. E.Yankwich l5 and a colloquium 16 and other papers l7 have been publishedon use and technique of isotope exchanges.The interaction of nuclear and chemical energies during nuclear reactionsis an engaging topic-the chemical state in which a newly created elementwill appear being dependent on many factors. A. G. Maddock l8 hasreviewed present knowledge on the chemical effects of nuclear recoil, and thevalency states of various fission products Sc, Te, I, Ce, and Br have beenstudied.19 The implications contained in suggestions such as La3+ --+Ce4+ + P- and Se032- --+ Br0,2- + p- are manifold.Attention must also be drawn to the symposium 2o held in March, 1949,by the Chemical Society in conjunction with the Chemistry Division, A.E.R.E.W.B. Lewis, Chem. Inst. Canada, Proc. Conf. hluclear Chem., 1947,16; 0. Volkoff,ibid., p. 20; L. G. Cook, ibid., p. 40; L. Yaffe, ibid., p. 117.Nature, 1949, 163, 624.Ibid., p. 2.Research, 1949, 2, 73.Ibid., p. 115.* R. A. Alpher, H. Bethe, and G. Gamow, Physical Rev., 1948, 73, 803; (Miss)M. G. Mayer and E. Teller, ibid., 1949, 76, 1226; P. S. de Toledo and G. Wataghin,ibid., 1948, 73, 79.0. Rloncke, Experientia, 1949, 5, 232, 440; P. Lacroute, Compt. rend., 1948, 226,1804; P. Chanson, ibid., p.997.lo Rev. Mod. Physics, 1948, 20, 585.l2 Research, 1949, 2, 154.l4 G. W. Dunlap and R. M. Lichtenstein, Elect. Eng. N . Y., 1948,65,469 ; 0. Erbacher,l5 Analyt. Chem., 1949, 21, 318.l6 J . Chim. physique, 1948, 45, 141.l7 M. Haissinsky and B. Pullman, J. Phys. Radium, 1947, 8, 33; (Mme.) P. Daudel,l1 Experientia, 1949, 5, 226, 278.l3 Angew. Chem., 1947, 59, A , 37.Angew. Chem., 1947, 59, A , 6.R. Daudel, (Mlle.) M. Martin, Bull. SOC. chim., 1949, D, 68.Research, 1949, 2, 556.l9 W. H. Burgus, T. H. Davies, R. R. Edwards, H. Gest, C. W. Stanley, R. R.2o J., 1949, 2nd Suppl. Issue.William, and C. D. Coryell, J . Chim. physique, 1948,45, 16588 INORGANIC CHEMISTRY.This covered the chemistry of the heavy elements, ( ( cis- and trans-uranics,”preparation, nuclear aspects and applications of radioactive tracers.In the discussion at the above symposium the problem of the actinongroup was prominent (still do the terms Zanthunon, proposed by Marsh, andact inon, consequently, appear preferable t o Eanthanide and actinide).Theconfusion of terminology is still evident in the actinon controversy. ThusE. Hayek and T. Rehner 21 find evidence which ( ( seems t o contradict thehypothesis of the beginning of an actinide group with thorium.” It seemsthat two ideal courses are open to the trans-actinium elements : (i) to fill upthe 6d shell and behave as members of ‘( normal groups,” (ii) to fill up the 5fshell to form an actinon series, analogous to the lanthanons. That thorium,protactinium, and uranium evidently exhibit some characteristics of bothdoes not prevent the elements neptunium to curium from adopting the placesin the actinon series that they would if the first three were to exhibit un-equivocally the expected number of 5f electrons.Thus the series to whichneptunium to curium almost certainly belong is one which probably has itsorigin in actinium even if the first three members of the series are renegade.On account of the divergence of those three elements, H. Haissinsky22called the series uranides to which the higher elements belong, thoughactinon (or -ide) seems preferable and more generally acceptable. Themore detailed chemistry of the lanthanons and actinons is, as last year,treated as a separate group. For convenience, thorium, protactinum,and uranium are dealt with under the same group, though the justificationfor that is now the real issue.The theory of ( ( half-bonds ” as advanced by R.E. Rundle has alreadybeen noted23 in connection with the hydroborons and other electron-deficient molecules. Space does not permit discussion here except to notethat the theory suggests the possibility of resonance between X-M Xand X M-X where only one orbital of the central atom is involved, e.g., ap orbital, utilising both (‘ ends ” in applying the maximum overlappingprinciple. One electron pair is thus involved in two effective ‘( half-bonds.”The theory has been applied to various valency problems, to hydrob0rons,~4ato aluminium alkyl~,~~b to the tetramethylplatinum tetramer,2k to metallicborides,24d t o other interstitial cornpo~nds,~~e and t o electron-deficientmolecules generall~.~~f Rundle has preferred the term ‘( excess orbital ”structures.Miscellaneous matters of interest include : colloquia on the chemicalbond 25 and on solid reactions; 26 the induced valency change, describedby P.W. Selwood 27 as (‘ valence inductivity,” brought about when atransition-group oxide is supported on a. high-area surface with which i t21 Experientia, 1949, 5, 114.23 Ann. Reports, 1947, 44, 52.24 (a) J. Amer. Chem. Soc., 1947, 69, 1327; ( b ) ibid., p. 2075; (c) ibid., p. 1561;25 J. Chim. physique, 1949,46, 187.26 Bull. Xoc. chirn., 1949, D, 23.22 J., 1949, S 241.(d) ibid., p. 1719; (e) Acta Cryst,, 1948,1, 180; (f) J.Chem. Physics, 1949,17, 671.27 J. Arner. Chern. Xoc., 1948, 70, 883DODD AND ROBINSON. 89may become isomorphous (as iron oxides and manganese oxides on rutile) ; 28heat of formation and stability of binary inorganic compounds; 29 the re-ported isolation 30 from unspecified natural materiaJs of new elements ofatomic number greater than 92. Two reports 31 of the American ChemicalSociety committee on atomic weights are available for 1948 and 1949-results of individual determinations will be mentioned below. 0. Kuba-chewski 32 has classified the elements into true metals, meta-metals, semi-metals, and non-metals according to values of electrical conductivity,co-ordination number, entropy, volume ratios, and changes in those quantitieson melting.A. R. Powell33 gives details of purification of the metals,palladium, cobalt, zirconium, iridium, niobium, tungsten, platinum,molybdenum, tantalum, rhodium, titanium, and nickel, used in the newbadge of office for the President of the Royal Institute of Chemistry. Mentionmust also be made of the general conclusion which W. F. Giauque34 hasreached after particular consideration of the dehydration of magnesiumhydroxide ( q . ~ . ) , namely : " that many equilibrium measurements involvinggases and finely divided dry solids produced by the evolution of gases, orformed by reaction with gases, do not correspond to properties of macroscopicmaterials."Group 0.-The interest in this group centres in experiments 35 now inprogress with the helium isotope 3He, naturally rare (1 part in 1.2 x lo6parts) but now available artificially.F. London36 has pointed to the im-portance of the results of S. G. Sydoriak, E. R. Grilly, and E. F. Hammell 37in the solution of the He-I1 pr0blem.3~ The unorthodox behaviour ofliquid helium *He can be explained if Bose-Einstein statistics are applied.If that can be justified, Fermi-Dirac statistics should apply to 3He,which would not then be expected to exhibit the abnormalities of liquidHe-11. That liquid 3He shows no discontinuity of flow velocity in coolingfrom 3" K., to 1.05" K., whereas liquid 4He shows a sudden increase below2.19" R., suggests that the Bose-Einstein statistics form a correct basis forthe explanation of liquid He-11.E.Wiberg and K. Karbe39 have been unable to find any evidence ofcompound formation between the inert gases argon, xenon, and krypton,and boron trifluoride, sulphur dioxide, hydrogen sulphide, dimethyl ether,or methanol. Boron trifluoride is not even miscible with liquid argon,xenon, or krypton.28 P. W. Selwood, T. E. Moore, M. Ellis, and K, Wethington, J. Amer. Chem. SOC.,29 A. E. Van Arkel, Research, 1949, 2, 307.30 B. Gysae and H. Korsching, 2. Naturforsch., 1947, 2, A , 415.31 G . E. F. Lundell, J . Amer. Chem. Soc., 1948, 70,3531 ; 1949, 71, 114.32 Trans. Faraday Soc., 1949,45, 931. 33 J . Proc. Royal Inst. Chem., 1949, 476.34 J . Amer. Chem. SOC., 1949, 71, 3192.35 H. A. Fairbank, C. T. Lane, L. T. Aldrich, and A. 0. Nier, Physical Rev., 1948, 73,36 Nature, 1949, 163, 694.38 L.Meyer and W. Band, Natumoiss., 1949,5,5.1949, 71. 69.3.729; J. G. Daunt, R. E. Probst, and H. L. Johnston, ibid., p. 638.37 Physical Rev., 1949, 75, 303.2. a m g . Chem., 1948,2!56,30790 INORGANIC (XIEMISTRY.Mass-spectral investigation 40 of isotope ratios in krypton and xenonhas given atomic weight values 83.91 and 131.31 respectively as againstInternational (1948) values 83.7 and 131.3.Group 1.-The main emphasis in this group has been on the chemistryof copper and its compounds and there is little relating to hydrogen andthe alkali metals. The preparation of 99% pure hydrogen deuteride hasbeen achieved 41 by reaction of deuterium oxide with lithium aluminiumhydride in n-butyl ether a t 0".The lower explosion limit in the reactionbetween hydrogen and nitrous oxide has been further investigated 42-thefact that molecular oxygen poisons the reaction (at 720-4330", 100-250 mm.total pressure, 40--80~0 N,O) suggests that a found minimum in the explosionlimit pressure-temperature curve is due to 2N,O --+ 2N, + 0, and conse-quent poisoning by H + 0, + M ---+ HO, + M. W. H. Schechter, J. K.Thompson, and J. Kleinberg43 have studied the oxidation of sodium in liquidammonia solution and find that rapid oxidation at -35" gives some oxidehigher than NaO,, though with slow oxidation a.t -77" and with precautionsagainst formation of NaNH, an oxide of empirical formula NaO,.,, , corre-sponding to 4Na0, : Na202, is formed. Sodium superoxide, NaO,, hasbeen prepared 44 in 92% yield from oxygen and sodium peroxide at 400-500" and about 30 atm.pressure. An effective magnetic moment of 2.07 B.m.was found, corresponding to 2-04 B.m. for the potassium compound 45. Thedissociation pressure of potassium hydride from 402" to 481" has beenmeasured 46 and the melting point of potassium hydroxide remeas~red.~'The value of 410" & 1" for the latter is higher than previously supposed,owing, it is suggested, to the exclusion of water by several hours' heating.H. F. Duckworth and B. J. Hogg*8 have determined the isotopic con-stitution of copper and arrive at a value 63.542 & 0.006 for the atomicweight, in excellent agreement with 0. Honigschmid and T. Johann~en?~whose chemical determination of 63.542 was accepted for the last revisionof the International value.H. Brown and M. G. Inghram 50 calculated63.55 on the basis of isotope abundance in terrestrial and meteoric copper.The oxidation of copper foil has been further investigated 51 with the aidof a tracer, 64Cu, and the distribution of the 64Cu+ ion in the copper(1) oxidelayer is offered as further evidence that diffusion of Cu+ is the rate-determin-ing step in oxidation. The preparation 52 of copper(1) sulphide by high40 M. Lounsbury, S. Epstein, and H. G. Thode, Physical Rev., 1947,72, 517.41 I. Wender, R. A. Friedel, andM. Orchin, J. Amer. Chem. SOC., 1949, '71, 1140.42 C. P. Fennimore and J. R. Kelso, ibid., p. 3706.44 S. E. Stephanon, W. H, Scheehter, W. J. Argersinger, and J.Kleinberg, ibid.,45 E. W. Neurnann, J. Chem. Physics, 1934,2, 31 ; see also Ann. Reports, 1947,44,62.4 7 R. P. Seward and K. F. Martin, J. Amer. Chem. SOC., 1949, 71, 3564.48 Physical Rev., 1947, 71, 212.6o Physical Rev., 1947, 72, 347.61 G . W. Castellan and W. J. Moore, J. Chem. Physics, 1949, 17, 41 ; see also Ann.bB R. Xol6 and R. Hocart, Compt. rend., 1949, 229, 424.$3 Ibid., p. 1816.p. 1819.A. HQrold, Compt. rend., 1947, 225, 249.49 2. anorg. Chem., 1944, 252, 364.Reports, 1948, 45, 86DODD AND ROBINSON. 91compression at room temperature of copper-sulphur mixtures has beenreported with X-ray confirmation. Copper(1) ~ e l e n i d e , ~ ~ Cu2Se, is the onlyproduct of the system copper-aqueous copper sulphate-selenium so long asall components are present.The system forms an electrolytic couple ofwhich copper is the negative electrode and selenium the positive. In thepresence of excess of selenium the oxidation by selenium, slow at roomtemperatures, commences as soon as all the copper is dissolved. The violetselenide Cu3Se, is formed. Further oxidation, accelerated a t highertemperatures, yields copper(I1) selenide.Basic copper chlorides 54 and double hydroxychlorides of copper( 11)and bivalent nickel, cobalt, magnesium, zinc, and cadmium 55 have beenstudied by W. Feitknecht and K. Maget. Cu(0H)Cl and four modificationsof 3Cu( OH),,CuCl,, or Cu,(OH),Cl (of which one is atacamite, not readilyprepared artificially) have been prepared and confirmed by X-ray analysis.No stable compound 2Cu(OH),,CuC12 appears to exist.The double hydroxy-chlorides studied were of the general formula 3Cu(OH),,MCl, formed by re-action between copper(1) oxide and solutions of the metal chlorides. Furtherhydrolysis studies 56 by H. Guiter include copper (11) sulphate, chloride, andnitrate, degree of hydrolysis increasing in that order, and the presence ofionic species Cu(OH)(NO,),2-, CUCL,(OH)~-, CU(SO,),(OH)~-, and Cu(OH)+has been suggested. Further to F. Karosy's observations of a volatile coppercompound formed on thermal decomposition of copper( 11) formate, re-ported 57 last year in connection with the attempted preparation of coppercarbonyl, A. Keller and F. Korosy 58 have identified the volatile compoundas copper(1) formate, which sublimes in vucuo at about 100" and decomposesat a higher temperature into copper, hydrogen, and carbon dioxide.Othercopper(I1) salts of fatty acids give unstable volatile copper(1) salts, andsilver gives salts similar to those of copper(1).Ethylenediamine (en),59 hydroxyethylenediamine (hn),60 diethylene-triamine (dnt) and other complexes of copper(I1) have been studiedspectroscopically and photometrically. [Cu(en)I2+, [Cu(en),12*, [Cu(hn)12+,[Cu(hn),I2+, [ C ~ ( h n ) ~ f ~ + , and [Cu(dnt),12+ are reported. The stability ofthe bis(diethylenetriamino)c~pper(II) ion suggests that copper is exhibitinga co-ordination number of six. The formation and existence of coppercyanide complexes only appears 62 possible when copper is present in higherconcentration than 0.5mlsr.m C .Goria, (fazzetta, 1940, 70,461.s6 Helu. Chim. Acta, 1949, 32, 1639; A. F. Wells, Acta Cryst., 1949, 2. 173.b5 Helv. Chim. Acta, 1949, 32, 1653.56 Bull. SOC. chim., 1948,15,945; Compt. rend., 1949, 228, 589.37 Ann. Reports, 1948, 45, 87.i~~ Nature, 1948, 162, 580.s8 H. B. Jonassen and T. H. Dexter, J . Amer. Chem. Soc., 1949, 71, 1553.6o J. L. Harvey, C. I. Tewksbury, and H. M. Haendler, ibid., p, 3641.dl H. A. Laitinen, E. I. Onstott, J. C. Bailar, and Sherlock Swam, ibid., p. 1550;J. G. Breckenridge, Canadian J. Res., 1948, 26, B, 11.B. Norberg and B. Jacobson, Acta Chem. Scad., 1949, 3, 17492 INORGANIC CHEMISTRY.A critical literature survey has been recently published,63 along with newwork, on the compounds formed by acetylene with copper and silver.Thereported existence of several complex salts is doubted, including many saidto contain Ag*C=CH. Silver acetylide shows considerable solubilityin aqueous solutions of silver perchlorate, and the formation of complexesof the form (Ag+),(Ag,C,),, or (Ag+),(C,2-), is assumed. A complexAg2C,,2AgC10, has been identified. On passing acetylene into suecientlyconcentrated copper(1) chloride solutions, in the presence of potassiumchloride, yellow or orange precipitates appear.64 It is suggested that thesecontain the group (CuCI),(C,2-), analogous to (Ag+),(C,2-) of which fhesolid nitrate exists.65 The equilibrium Ag,C, + 2H+ += C2H2 + 2Agf hasbeen measured.66The oxidation of iodine by solutions of silver sulphate in sulphuric acidappears, from kinetic studies,67 to involve two processes the first being fastand the second slow and rate-determining :21, + 2H,O + Ag,SO, --+ 2AgI + €€,SO, + 2HOI3HOI + Ag2S0, + 2AgI + H,SO, + HIO,No doubt these are themselves composite but the oxidising power of suchsolutions is thought to be due to IO- and 10,- ions rather than to the presenceof hydrogen peroxide.Hydrolysis and decomposition of aqueous tetrachloroaurate(II1) solu-tions have been investigated by N.Bjerrum.6s Hydrolysis to form[Au(OH),Cl, -,I- occurs rapidly for replacement of the first two chlorineatoms but thereafter is slow. No aquo-complexes are formed. Reductionto univalent gold by the reaction AuC1,- --+ AuC1,- + C1, also occurs.Normal potentials for a number of related electrode reactions are also given.W.L. Gent and C. S. Gibson 69 have prepared diethylthiocyanatogold andshown i t to be dimeric. The compound is remarkable for the resistanceof sulphur-gold linkages to the co-ordinating action of nitrogenous bases.The structure (I) is preferred to (11).CN,S--C=N\%EC-S/Et2Au AuEt,(I.) CN (11.1Group II.--The details of the redetermination of the atomic weight ofberyllium, by ratios BeC1, : 2Ag, BeCl, : 2AgC1 and BeBrz : 2Ag, BeBr, : BAgBr,63 R. Vestin and E. Ralf, Acta Chem. Scand., 1949,3, 101.1 3 ~ R. Vestin, ibid., p. 650.65 J. A. Shaw and E. Fisher, J . Amer. Chem. Soc., 1946, 68, 2745; Ann. Reports,1313 R. Vestin and A. Somersalo, Actu Chem.Scand., 1949,3, 125.13' (Mlle.) M.-L. Josien and M. D. A. Williams, BUZZ. Soc. chim., 1949, 16, 547, 551;68 Bull. SOC. chim. Belg., 1948, 5'9, 432,1948, 45, 88.(Mlle.) M.-L. Josien, Compt. rend., 1949, 228, 1021.69 J., 1949, 1835DODD AND ROBINSON. 93are now available.70 The value 9.013 -J= 0.0004 compares with 9.0126from mass-spectral data. The International value (1948) is 9.02. Thevapour pressure of beryllium metal at elevated temperatures has beenmeasured.71 L. Hackspill and J. Besson 72 have shown that the productionof pure beryllium by hydrogen reduction of beryllium chloride is rendereddiEcult by the proximity of the temperature of reduction to the fusionpoint of the metal and by the difficulty of finding an adequate supportinert to beryllium.The possibility of using beryllium bromide or iodideis discussed. A general article 73 by Besson on the preparation, technicaldevelopment, and uses of beryllium compounds is available. When watervapour is brought into contact with beryllium oxide a relatively rapidvolatilization occurs 74 which is greater than can be explained by the vapourpressure of beryllium oxide a t the same temperature. This is not observedwith beryl or magnesia. The volatilisation rate increases with increasedtemperature, and a t tempera.tures above 1250" an observable reaction occursto give a volatile compound which condenses, on cooling, with decompositionto beryllium oxide. The nature of the volatile compound is not apparent.The preparation, properties, and Raman spectra of diethylberyllium havebeen described.75In comparing34 the true dissociation pressure in the systemMg(OH), (cryst.) + MgO (cryst.) + H,O (g.) as determined by the thirdlaw of thermodynamics, with that obtained experimentally to an accuracyof 0.1 %, W.F. Giauque finds a 130% difference. He suggests that the lowerexperimental values are due to the colloidal nature of the magnesium oxideproduced under equilibrium conditions. Thus i t appears that equilibria,which are reproducible or even in agreement with the third law, cannotnecessarily be accepted as corresponding to the thermodynamic propertiesof macrocrystalline phases. S. J. Gregg and I. Razouk 76 have measuredthe rates of isothermal dehydration of precipitated magnesium hydroxideand natural brucite and find the rate and the heat of activation to vary fromsample to sample.The equilibrium MgCO, MgO + CO, has &Is0 beenmeasured.Further studies include basic magnesium nitrates,78 the system calciumsulphate-sodium ~hloride,'~ the hydrates of calcium sulphite,80 the kineticsand catalysis 81 of production of calcium carbonate from reaction between0. Honigschmid and T. Johannsen, 2. Naturforsch., 1946, 1, 650.71 R. B. Holden, R. Speiser, and I€. L. Johnston, J. Amer. Chem. SOC., 1948, 'SO,72 Bull. Xoc. chim., 1949, 16, 113. 73 Ibid., 1949, D, 15.74 C. A. Hutchison and J. G. Malm, J. Amer. Chem. SOC., 1949, '71, 1338.7 5 J. Goubeau and B. Rodewald, 2. anorg. Chem., 1949, 258, 162.76 J., 1949, S 36.77 E.Cremer, 2. anorg. Chem., 1949, %8, 123.78 (Mme.) L. Walter-LBvy, Compt. rend., 1948, 227, 1231.79 J. By6 and J. G. Kiehl, Bull. Xoc. chim., 1948,15, 847.81 R. Stumper and F. Classen, Compt. rend., 1949,228,83, 184.3897.F. W. Matthews and A. 0. MeIntosh, Canadian J. Res., 1948,26, B, 74794 INORGANIC CHBMISTRY.calcium bicarbonate and hydroxide and between calcium sulphate andsodium carbonate.Mass-spectrographic determinations 82 of 'isotope ratios in zinc andcadmium give values 65.40 and 112.42 for atomic weights comparedwith International values 65.38 and 112.41. The dissolution of cadmium 83and zinc 84 in nitric acid in the presence of platinum and a 1% solution ofm-phenylenediamine show little or no formation of nitric or nitrous oxidesor hydrogen, but ammonia and hydroxylamine increase considerably inamount.Equilibria involving mercury(I1) and halide ions have been studied byL.G. Sillen, who has surveyed 85 seven preceding papers by himself and hiscollaborators. For all halogens it was only found necessary to assume theexistence of HgX+, HgX,, HgX,-, and HgX,,-. J. Lamure has studied 86the oxychlorides and oxybromides of mercury and has further verified 87that mercury(1) oxide, Hg,O, is the primary product of the action of baseson mercury(1) salts. Previous negative evidence is explained by theobservation that the mercury(1) oxide is stable in water in the absence oflight but disproportionates to mercury and mercury(II) oxide on drying.Group IIL-The majority of the contributions to Group I11 chemistryconcern boron.High-purity boron has been prepared 88 by the hydrogenreduction of boron tribromide vapour in a quartz tube. Diborane anddiboron monohalides have been produced 89 by hydrogen reduction ofborane halides over active metals (aluminium, zinc, magnesium, moltensodium) at temperatures above 300". The reaction of gaseous boron halideswith active metal hydrides also yields diborane, wherefore i t is suggestedthat active hydrides are initially formed at the metal surfaces. Freezing-point measurements on the diborane-ammonia system a t 195" K. haveindicated a compound B,H,,xNH, but no sign of dissociation or associ-ation. Various bina.ry systems involving diborane and hydrogen chloride,boron trichloride, ethane, or boron trifluoride have been studied.Q1 W.Eggersgluess, A.G. Monroe, and W. G. Parker 92 have redetermined the heatof formation of boron trioxide and find a value of 281.1 zfr: 3.1 kcals./mole,as against previously published values of 279.9,93 349,94 and 335 95 kcals./mole.The higher values axe attributed to the use in both cases of impure boroncontaminated with combined hydrogen. If that is the case, the heat of82 W. T. Leland and A. 0. Nier, Physical Rev., 1948, 73, 1206.83 S. D. Radosavijevic, Bull. SOC. chim. Belgrade, 1948, 13, 83.84 A. M. Leko and S. D. Rados;Etvljevic, ibid., p. 90.E 5 Acta Chem. Scand., 1949, 3, 539.86 Bull. SOC. chim., 1948, 15, 1019..88 R. Kiessling, Acta Chem. Scand., 1949, 2, 707.89 D. T. Hwd, J . Amer. Chem.SOC., 1949, 71, 20.so G. W. Rathjens and K. S. Pitzer, ibid., p. 2783.91 L. V. McCarty, ibid., p. 1339.ss D. Berthelot, '' Thermochimie " (Paris 1897), Vol. 11, p. 122.s4 W. A. Roth and E. Boerger, Ber., 1937, 70, 48, 971.95 B. J. Todd and R. R. Miller, J . Amer. Chem. SOC., 1946,68,630.87 Compi!. rend., 1948, 228, 918.92 Trans. Faraday SOC., 1949,45,661DODD AXD ROBINSON. 95formation of diborane requires revision and becomes -26 kcals. /mole,compared with the previous value9* of +44 kcals./mole. Thus B2H6would be an endothermic compound. Methods of purification to bett'erthan 99% are reported, heats of formation 96 and vibrational spectra 97 ofvarious metal borohydrides have been measured, and the spectra have beenshown to be in agreement with the bridge structure formulati~n.~~ Alu-minium borohydride will ignite spontaneously in air ; 99 water vapour givingrise to rapid hydrolysis is a pre-requisite for explosion at room temperature.Reference has already been made in these Reports to the compounds oftype BH,,NH,, BH2*NH2, BH:NH, and their derivatives and polymers.A.B. Burg and C. L. Randolph2 have prepared compounds B2H,*NHMeand B2H,*NMe2 from diborane, methylamine, and dimethylamine, Thedimethyl compound is a stable solid (m. p. 74.5-75") and can be keptpermanently, The monomethyl compound un 3ergoes slow and reversibledissociation into diborane and the BH,*NHMe dimer, for which the bridgemodel (111) has been suggested.l Burg and Randolph now suggest astructure (IV) for the aminoborane and derivatives.Structure (IV) is thusintermediate between (111) and the hydrogen-bridge structure of diborane.(111.)Boron trifluoride3 has been shown not to react with phosphoric oxide,iodine pentoxide, or iodine, but combination with phosphorus trichloridegives BF,,PCl,, stable up to - 6". Structures and bond energies of a numberof fluoroborates and related compounds have been obtained4 from Ramanspectral data by J. Goubeau.in 60% yield by passing gaseous boron trichloride through a glow discharge.The compound has been well characterised ; vapour density indicates B,Cl, ;complete hydrolysis occurs with aqueous sodium hydroxide a t 70"; theliquid on standing a t room temperature for 72 hours gives 21 "/o decompositioninto boron trichloride and other undetermined chlorides ; with boron tri-bromide the compound B,Br, is obtained.The similar preparation andproperties of B214 have been described : i t is a crystalline pale yellow solidDiboron tetrachloride has been prepareds6 W. D. Davis, L. S. Mason, and G. Stegeman, J . Anzer. Chem. SOC., 1949, 71, 2775.s7 W. C. Price, H. C. Longuet-Higgins, B. Rice, and T. F. Young, J . Chem. Physics,1949, 17, 217.Ann. Reports, 1947, 44, 54.ss E. J. Badin, P. C. Hunter, and R. N. Pease, J . Amer. Chem. SOC., 1949, 71, 2950.Ann. Reports, 1948, 45,92 ; see also E. Wiberg, A. Bolz, and P. Buchheit, 2. anorg.J . Amer. Chem. Xoc., 1949, 71, 3451.P. Baumgarten, Ber., 1948, 80, 517.T. Wartik, R. Moore, and H. I. Schlesinger, J.Amer. Chem. Xoc., 1949, 71, 3265.W. C. Schumb, E. L. Gamble, and M. D. Banns, ibid., p. 3225.Chem., 1948, 256, 285; E. Wiberg, K. Hertwig, and A. Bolz, ibid., p. 177.4 Angew. Chem., 1948, 60, A , 7896 INORGANIC CHEMISTRY.which decomposes slowly at room temperature into BI, and black non-volatile (BI)z. G. Carphi has suggested that boric acid solutions containonly two ionic species in equilibrium, probably B503H2- and B03H2-.Some new alkali-metal perborates have been described by A. H. Fathallahand J . R. Partington.8A comprehensive phase-rule and X-ray investigation of the systemA1,O3-SO3-H2O, leading to the recognition of a dozen new compounds, hasbeen made by H. Bassett and T. H. Go~dwin.~ Methods of productionand the properties of aluminium fluoride have been critically reviewed.1°H.Brintzinger l1 has determined the ionic weight of the aluminate ion,among others, and the indication is that it is a binuclear complex, either[ (HO),A1(OH)~l( 0H)J4- or [ (HO),A102Al(OH)4]6- where the aluminiumatoms are linked by an oxygen-bridge structure.Ethylenediamine compounds of indium have been prepared anddescribed.12Though there is exchange l3 between uni- and ter-valent thallium inaqueous solution, H. McConnell and N. Davidson l4 have found no evidencefor exchange of 204Tl between the two valency states in solid TI2&, andTI2C1,. The implication is that the ions of the two valency states do notoccupy equivalent positions in the lattices of those compounds. The halidesT12X3 are more coloured than the halides of unmixed valency, but theabsorption spectrum shows no significant interaction absorption.Fromtitration curves of thallium(1) nitrate and sodium thiosulphate, the existenceof a number of the thiosulphate-thallium complex anions has been deduced.15Lanthanons and Actinons.--Isotopic constitutions have been deter-mined mass-spectrographically for lanthanum, cerium, l6 praseodymium,neodymium,17 and samarium.ls Resultant atomic weight values, withinternationaJ values in parentheses, are respectively 138.92 (138*92), 140.10(140.13), 140.92 (140~92)~ 144.25 (144-27), 150.35 (15043).N. E. Ballou19 has discussed the existence of promethium in Nature,and C. Feldmann 2O has described its arc spectrum. The magnetic suscepti-bilities of yttrium ,21 samarium,22 gadolini~m,~3 and thulium 24 have beendetermined.N. K. Dutt 25 has described the composition and isolationBull. Soc. chim., 1949, 16, 334.Nature, 1949, 164, 952. @ J., 1949, 2239.10 T. R. Scott, Counc. Sci. I d . Res. Australia, 1947, Bull. 230.I f 2. anorg. Chem., 1948, 256, 98.1 2 G. J. Sutton, J . Proc. Austral. Chem. Inst., 1948, 15, 356.la R. J. Prestwood and A. C. Wahl, J . Amer. Chern. Soc., 1949, 71, 3137.l4 Ibid., p. 3845.l5 J. Kamecki and J. Wolny, Roczn. Chem., 1948,22, 48.l6 M. G. Inghram, R. H. Hayden and D. C. Hess, Physical Rev., 1947,72, 967.l7 Idem, ibid., 1948, 74, 98. Idem, ibid., 73, 180.2o J . Amer. Chem. Soc., 1949, 71, 3840.21 0. M. M. Hilal and S. Sugden, J., 1949, 135.22 S.Sugden and S. R. Tailby, ibid., p. 136.25 J. Indian Chem. Soc., 1949, 26, 405.l9 Ibid., p. 630.Idem, ibid., p. 137. 24 Idern, ibid., p. 139DODD AND ROBINSON. 97of several double thiosulphates of the lanthanons, and an improved synthesisof lanthanon '' acetylacetonates " has been devised.26 The purificationof lanthanum has been effected 27 by precipitation of the hydroxide by air-borne ammonia, the method enabling a close control of pH. R. C. Vickery 28has also investigated the solubility of lanthanon hydroxides in fused ammoniumnitrate with a view to lanthanum purification and separation of cerium andyttrium. H, Hartmann 29 has examined discrepancies in the literatureconcerning lanthanon carbides and cyanamides. A complex of insolublepraseodymium trifluoride has been prepared,30 which is soluble and probablyhas the formula KPrF4.Samarium has been isolated31 from lanthanonmixtures by reduction of SmCl, to SmC1, by magnesium in absolute alcoholcontaining a few drops of concentrated hydrochloric acid. Samarium(I1)hydroxide, citrate, fluoride, and carbonate were then obtained by precipitation.When acid solutions of cerium(1V) perchlorate are exposed to ultra-violet light, reduction to cerium(II1) occurs with evolution of oxygen.L. J. Heidt and M. E. Smith32 have presented evidence for a mechanisminvolving the formation of cerium(1V) dimers. This is supported by thefurther kinetic measurements of D. Kolp and H. C. Thomas.33 Thus :hvZCeIv + Ce2V+Ce2r*CeaV* + H20 -3 2Ce111 + 2Hf + 40,Inhibition by Ce3+ ions is thought to be mainly due to deactivation of theenergetic dimer.It occurs to the Reporters that collision with Ce3+ ionsmight be more effectual in deactivation than other collisions by virtue ofexchange between the dimer and Ce3+ ions. The dimeric ions are supposedto be [Ce-O-CeI6+, [HO-Ce-O-CeJ5+, and/or [HO-Ce-O-Ce-OHI4 t .Some further general accounts of the chemistry of the actinons areavailable, and the work of W. H. Zachariasen34 on the crystal chemistryof 4j and 5j elements must be mentioned. This includes a summary ofstructural information on 55 new compounds : for a more detailed accountsee the Crystallographic Section of these Reports. Z. Szab0,35 on thebasis of periodicity in a number of physical properties, supports the idea ofthe actinon series.T. J. Hardwick36 and R. E. Connick37 have sum-marised methods of preparation and present knowledge of valencies exhibitedby the actinons. The absorption spectra38 of anhydrous chlorides ofuranium(IV), neptunium(IV), plutonium(III), and americium(II1) show sharplines clustered in groups. This characteristic is similar to the lanthanons.26 J. G. Stites, C. N. McCarty, and L. L. Quill, J . Amer. Chem. SOC., 1948, 70, 3142.27 R. C. Vickery, J., 1949, 2506.29 Angew. Chem., 1948, 60, A , 74.30 T. P. Perros and C. R. Naeser, J . Amer. Chem. Soc., 1949,7l, 3847.31 A. F. Clifford and H. C. Beachell, ibid., 1948, 70, 2730.82 Ibid., p. 2476.34 Acta Cryst., 1949, 2, 388, 390.36 Chem.Inst. Canada, Proc. Conf. Nuclear Chem., 1947, 44.57 R. E. Connick, J., 1949, S 235.5 8 S. Freed and F. J. Leitz, J . Chern. PhySics, 1949,17, 540.28 Ibid., p. 2508.33 Ibid., 1949, 71, 3047.35 Physical Rev., 1949, 76, 147.REP.-VOL. XL-. 98 INORGANIC CHEMISTRY.Even at room temperature, americium salts show the sharpest lines knownfor crystals, only europium(1II) salts being comparable. Thus the basicelectronic state 'Po, with six 5f electrons, is very probable for Am3t.J. T. Yang and M. Haissinsky3B have described a chromatographicseparation, on a synthetic resin amberlite IR-100, of actinium and lanthanum.Iodides of thorium(II1) and (11) have been prepared40 and are deeplycoloured compounds analogous to lower zirconium and hafnium iodides.450-550' ThI, + Th T,-~T' 2Th1,ZThI, + 2Th1, 3Th1, + Th G' 4Th1, 7' 450-550' 550-600"Hydrolysis of the salts is vigorous and yields thorium(1V) salts andhydrogen equivalent t o the reducing power.A. G . Maddock and G. L.Miles 41 have described some coprecipitation experiments with protactiniumwherein they found, with a variety of reducing agents, no evidence for a loweroxidation state of protactinium than five. They also give a new method forextraction in which protactinium is precipitated with manganese dioxide.On the other hand, G. BouissiBres and &I. Haissinsky42 have claimed afluoride of a lower valency of protactinium, both in tracer and in ponderableamount, by use of zinc amalgam and the Jones reductor. The fluoride,which is insoluble and can be precipitated without carrier or withlanthanum(II1) fluoride, is clearly of value for separation of protactinium.A variety of electropositive metals have been shown 43 to displace protactiniumfrom hydrofluoric acid solution.The hydrolytic behaviour of uranium, plutonium, and neptuniumin valency states (111) and (IV) has been studied.** The hydrolysis Pu3+ +H20 = Pu(OH)~+ + H+ occurs with pK = 7-23 in 0*069~-perchloratesolution ; a similar hydrolysis is suggested for uranium(II1) and neptun-ium(III), though their study is rendered very difficult by their powerfulreducing properties.The hydrolysis M4+ + H,O = MOH3+ + H+ takesplace up to 90?& for uranium(1V) and 50% for plutoniurn(IV), and eventually,above pH - 1, there is formation of polymers analogous to those formed byzirconium( IV) and neptunium(1V).However, the U(II1)-U(1V) reversiblecouple has been measured45 polarographically in acid solution and is in-dependent of hydrogen-ion concentration, suggesting U3+ =& U4+ + einvolving unhydrolysed ions. The hydrolysis of uranium tetrafluoridein the vapour phase a t 200--500" has also been studied.46 Uranium(V)39 Bull. Soc. chim., 1949, 16, 546.40 J. S. Anderson and R. W. M. D'Eye, J., 1949, S 244 ; E. Hayek and T. Rehner,Experientia, 1949, 5, 114.4 1 J . , 1949, S 248.42 Compt. rend., 1948, 226, 573; J., 1949, S 248.43 (Mme.) M. Camarcat, G . Boussihres, and M. Haissinsky, J . Chim. physique, 1949,44 K. A. Kraus and F. Nelson, U.S. Atomic Energy Commission Report, 1948, 1888.45 E. S.Kritchevsky and J. C. Hindman, J . Amer. Chem. Soc., 1949, 71, 2096.46 L. Domange and (Mile.) M. Wohlhuter, Compt. T e d . , 1949,228 1591.46, 153DODD AND ROBINSON. 99solutions have been prepared 47 by electrolytic reduction and have beenshown to have an optimum stability against disproportionation in the rangebetween pH 2 and 4. The formula UO,+ for the ions present is consistentwith the behaviour of the solution on passage of oxygen through it. NearpH 2, species U4+, U*OH3+, UO,', and UOZ2+ coexist in equilibri~m.~~ Afurther electrochemical study 49 of uranium and plutonium suggests that theion UO,+ disproportionates as soon as it is formed, but the pH is notspecified and no doubt was greater than 2 , A mechanism for uranium(V)disproportionation has been suggested 50 thus : UOit + Hi --+ UO*OH2t,UO,T + UO*OH2+ UO?+ + UO*OH+, UO*OH+ + stableU(1V) species.That the U(V) ion is U02+ is verified by ths insensitivity of the coupleUO,+ =+ UO?+ + e to pH (presumably within the optimum stabilityrange).The existence of plutonium(V) in solution is deduced 49 from inter-action absorption in the spectra of mixtures containing Pu(1V) and Pu(V1).Furthermore, the reaction 2H20 + U4+ + 2Pu4+ _I, UOZ2+ + 2Pu3+ + 4Hfhas been shown to occur.Exchange of uranium, 233TJ being used, has been shown 51 to occur betweenU4+ and the uranyl ion UO,,+, and the rate of exchange increases twenty-fold on irradiation with a tungsten-filament lamp. Exchange of oxygenbetween water and the uranyl ion has indicated the formula U02k ratherthan U(OH)42- unless the latter ion has two oxygen atoms more weakly boundthan the other two.On the other hand, J. Faucherre 53 has proposedthe formula U,O4(OH),2 +, H. Guiter 54 has given evidence for U20,(OH),2f,UO,(OH)+, UO,(OH)NO,, and U0,(N03),0H2-, and S. Ahrland 55 hasshown that monomeric UO$+ only exists in aqueous solution below pH 2.J. Sutton 56 has made cryoscopic and absorption-spectral measurementsto prove the formation of U,OS2 + , U3OS2+, U,O,OH', U308( OH),, andU,08(OH)3- but not UO,(OH)+ or UOJOH),. The formation of complexesof uranium hexafluoride and the use of hydrogen fluoride-free materialfor the purpose have been discussed by H. Martin.57 Heats of vaporisation 58of solid and liquid uranium hexafluoride, and its density 59 by a flotationtemperature method have been recently measured. Measurements 6o ofspecific heat of uranyl fluoride have led to calculations of enthalpy and ofentropy.Redox titrations followed spectrophotometrically and isolation of the com-47 K.A. Kraus, G. L. Johnson, and IF. Nelson, U.S. Atomic Energy Commission48 K. A. Kraus and F. Nelson, ibid., p. 2517.4B R. H. Betts, Chem. I m t . Canada, Proc. Conf. Nuclear Chem., May, 1947, 68.50 D. M. H. Kern and E. F. Orlemann, J . Arner. Chem. SOC., 1949,71,2102.c x R. H. Betts, Canadian J . Res., 1948, 26, B, 702.53 Compt. rend., 1948, 227, 1367.54 Bull. Soc. chim., 1947, 14, 64.56 J . , 1949, S 256.58 J. F. Masi, J . Chem.Physics, 1949,17,755.5B H. J. Koge and M. T. Wechsler, ibid., p. 617.60 P. F. Wacker and R. K. Cheney, J . RBS. Hat. Bur. Stand., 1947,39,317.Report, AECD, 1948, 2460; J . Arner. Chem. Soc., 1949,71, 2510.56 Acta Chern. Scand., 1949, 3, 374.57 Angew. Chern., 1948, 60, A , 73100 INORGANIC CHEMISTRY.pound NaNpVIO,(OAc),, have established the existence of +4, 3.5, +6oxidation states of neptunium. Neptunium(V) is quite stable in acidsolution. A number of solid compounds of neptunium have been prepared,62including halides, oxides, oxysulphides, and nitrate. Detailed accountsare now available of the chemistry of plutonium 63 and of its first isolation 64in the pure state and in pure compounds. R. E. Connick andW. H. McVey 65 have identified two peroxy-compounds of plutonium(IV), abrown one, probably (Pu*O*O*PU*OH)~+ or (V), and a red one, probably(HO~Pu-O*O*Pu*OH)4+ or (TI).Group IV.-The production of diamonds in the laboratory has beenfurther discussed by D.P. Mellor,66 and a long article 67 by H. Brusset isavailable on the chemistry of elementary carbon. The conversion of Baf4C0,into more useful compounds containing the carbon isotope has been accom-plished as follows. Carbon dioxide is obtained by treatment with acid andis then reduced to methane, 14CH4, by hydrogen a t 330" over nickel-thoriumoxide catalyst,68 or to elemenary carbon, 14C, with magnesium.6g Themethane may then be converted into carbon tetrachloride, l4Ccl4, by photo-chlorination, and the amorphous carbon into hydrogen cyanide, H14CN,by treatment with ammonia at 1000".The bond energies of various carbon-metal linkages have been estimated 70from the heats of combustion of the corresponding metal alkyls (mainlymethyls).Very thorough purification of the compounds used led to revisedmelting points for dimethylcadmium ( - 2.4") and trimethylaluminium(15.4"). Linear structures for dimethyl-zinc and -mercury have beendeduced 71 from vibration spectra, and force constants have been calculatedfor the carbon-metal bonds. The C-Zn bond shows greater ionic characterthan the C-Hg bond.Carbonyl selenide, previously obtained 72a by the reaction of carbonmonoxide on selenium, and fairly fully characterised, has now been prepared 721,by passing earbonyl chloride over aluminium selenide at an optimum tempera-ture of 220".The resultant aluminium chloride has an autocatalytic effect61 J. C. Hindman, L. B. Magmusson, and T. J. La Chapelle, J . Amer. Chem. Soc.,1949, 71, 687.62 S. Fried and N. Davidson, ibid., 1948, 70, 3539.63 B. G. Harvey, Chem. Inst. Canada, PTOC. Conf. Nuclear Chem., May, 1947,60.64 B. B. Cunningham and L. B. Werner, J . Amer. Chem. SOC., 1949,71, 1521.6 5 Ibid., p. 1534. Ann. Chim., 1948, 3, 679.6 8 W. H. Beamcr, J . Amer. Chem. SOC., 1948, 70, 3900.'O L. H. Long and R. G. W. Norrish, Phil. Trans., 1948-49,241, 587.72 (a) T. G. Pearson and P. L. Robinson, J., 1932, 652 ; (a) 0. GIemser and T. Risler,66 Research, 1949, 2, 314.R. Abrams, ibid., 1949, 71, 3835.H. S. Gutowsky, J .Chem. Physics, 1949, 17, 128.2. Naturforsch., 1948. 3, B, 1DODD AND ROBINSON. 101on the reaction. A number of physical properties have been remeasured,and others determined for the first time. Carbonyl cyanide has been similarly~haracterised.'~ The preparation of carbonyl chloride from carbon tetra-chloride and oleum has been shown 74 to follow the course H2S207 + CCI, -+COCI, + 2HS03C1 and H2S0, + CCI, -+ COCI, + HCl + HS0,Cl. Thermo-dynamic properties of carbonyl chloride have been thoroughly examined byW1 F. Giauque and W. M. J0nes.7~ For such metal carbonyls and nitrosylsas Fe2(CO),, Co2(CO),, and Fe(NO),X (where X is S-K+, Cl,, I,, etc.),R. V. G. Ewens 76 has suggested bridge structures involving direct metal-metal linkage.Liquid anhydrous hydrogen cyanide has been thoroughly investigatedas a solvent by G.Jander and B. Griittner.77 Perchloric and nitric acidsare acidic in the solvent, which has a small conductivity probably due to2HCN =+ (H*HCN)+ + CN- C- (H,CN)* + CN-. Nitric acid is a weakacid and apparently loses its oxidising power in liquid hydrogen cyanide.Acid-base indicakors and the solvolysis of many salts, especially silver salts,are discussed. Iron(III), silver(I), and mercury(1) cyanides are amphoteric 78in the expect*ed sense : AgCN Ag+ + CN- and AgCN + CN- z+=Ag(CN)-. The trimethylammonium salt of the latter ion has been isolatedamong others. Sulphur dioxide and trioxide in the solvent have an acidicnature 79 but yield very unstable acid analogues, thus :OHSO, + HCN OS/ + NC*Sd + H+'m i \:I- Solvolysis of sulphuryl chloride leads to OS(CN)Cl.The oxidation of cyanide by iodine and the various redox systems involvingcyanide, iodide, iodine, and iodine cyanide have been studied,80 as has alsothe possible polymerisation 81 of cyanic acid.The existence of dicyanicacid is doubted; equilibrium between HOCN and HNCO is suggested andany polymerisation is reckoned to give cyamelide and cyanuric acid. Acomplete structural determination 8, of the mineral trona has been made andit is shown to contain the ion (HCz06)3- or [ 0 >C-0 . . . H . . . OJol'-.0 \OAttempts have been made to prepare a non-cubic modification of silicon,and an unstable, probably hexa.gona1, form has been obtained.83 Studies73 0.Glemser and V. Hiiusser, 2. Natetrforsch., 1948, 3, B, 159.74 R. K. Murphy and F. H. Reuter, J . Proc. Austral. Chem. Inst., 1948, 15, 144.75 J . Amer. Chem. Soc., 1948, 70, 120.76 Nature, 1948, 161, 530.7 8 Ibid., p. 114.7 7 Ber., 1948, 81, 102, 107.7s Ibid., 1947, 80, 279.R. Gauguin, Bull. SOC. chim., 1948,15, 1052.A. E. A. Werner and J. Gray, Sci. Proc. R. Dublin Soc., 1947, 24, 209.82 C. J. Brown, H. S. Peiser, and (Miss) A. Turner-Jones, Acta Cryst., 1949,2, 167.83 F. Heyd, F. Khol, and A. Kochanovskb, Coll. Czech. Chem. Cmm., 1947,12, 502102 INORGANIC CHEMISTRY.have also been made of sodium silicate hydrates,84 preparation of siliconsulphide~,~~ hydrolysis of silicon halides,s6 and the preparation of ethoxy-silicon fluorides.87 Magnetic-susceptibility measurements 88 have indicated[SnCI,(H,O),], [KSnCl,(H,O)], K2[SnC14], and K,[SnC1,(H20)2],H20 forSnCI2,2H,O, KSnCI,,H20, K,SnCI,, and K2SnCl, ,3H,O, respectively, andthe formulation is in agreement with the difficulty of dehydrating tin(I1)chloride hydrates, and poor electrical conductivityof its solutions.Hydrolysisstudies *@ of sodium stannates have sugggested the presence of species(NaHSnO,),, NaHSnO,, Na,HSn0,2+, and Sn0,H-.Radio-isotopes of lead have been used @O to investigate the exchangeof lead in the solid state between the nitrate and chromate, the chloride andchromate, the chloride and sulphate. There is a temperature thresholdof exchange which is related to the temperature of fusion of the salt. Thethermal decompositions of lead oxalate @l and nitrate @, have been studied.The action of heat on lead iodide 93 in vacuum and in the presence of oxygengave no visible decomposition at 729" in the first case and in the second casegave oxides of lead and some oxyiodides which were not isolated.Aceto-bromides and acetoiodides of lead have been prepared,@4 including a newcompound, Pb,(OAc),I.Preparation and properties of amides of titanium(II1) have been recentlyde~cribed,@~ e.g., Ti(NH,), and KTi(NH,),. H. R. Hoekstra and J. J.Katz 96 have prepared borohydrides of titanium(III), zirconium(IV),hafnium(IV), and thorium(1V). The last is the most salt-like, but all arethe most volatile compounds known for each element in the stated valencyConnick and McVey B7 have investigated0 QH the nature of complex species formed betweenii---il-c-cH=-CCE', zirconium(1V) and thienoyltrifluoroacetone (in-(= HX) set).Two-phase distribution between waterand benzene indicates that ZrX, is the only important species in benzenesolution. The nature of sulphates, fluorides, chloride, nitrate, peroxide, andoxalate of zirconium( IV) was also studied. Complex compounds betweenzirconium(1V) and alizarin and related compounds have been investigated 98and compared with the hafnium(1V) compounds.state.\S/BP H. Lange and M. von Stackelberg, 2. anorg. Chem., 1948, 256, 273.*5 L. Malatesta, Cazzxettu, 1948, 78, 702.86 J. Goubeau and R. Warncke, Angew. Chem., 1948, 60, A , 73.87 H. J. Emeleus and H. G. Heal, J., 1949, 1696.89 E.CarriAre, H. Guiter, and M. Ronso, BUZZ. SOC. chim., 1948,15, 946.@1 L. L. Bircumshaw and I. Harris, J., 1948, 1898.S2 A. Nicol, Compt. rend., 1948, 226, 253.93 Idem, Bull. SOC. chim., 1949, 16, 280.94 E. Grillot, ibid., 3.948, 15, 1035.95 0. Schmitz-Dumont, P. Simon, and G. Broja, 2. awrg. Chem., 1949, 258, 307.98 J . Amer. Chem. SOC., 1949, 71, 2488.9' Ibid., p. 3182.08 J. F. Flagg, H. A. Liebhafsky, and E. H. Winslow, ibid., p. 3630.E. Gaillot, Compt. rend., 1948, 226, 496.(Mlle.) E. Gleditsch and P. T. Cappelen, ibid., 1949, D, 64DODD AND ROBINSON. 103Group V,-A redetermination 99 of the chemical atomic weight of nitrogen,using ratios NH4Cl : Ag, NH,Cl : AgCl, NH,Br : Ag, and NH,Br : AgBr, hasgiven a value 14.008 identical with the International value (1948).Animproved apparatus for carrying out reactions in liquid ammonia a t itsboiling point has been described and provides for titration, filtration,and purification operations, Electron-diffraction measurements havebeen made on the fluoride N2F2, and distances worked out on the basis of aconfiguration F*N:N*F. Structural investigations giving bond lengths havealso been carried out in solid N20a3 and gaseous NO,.4 Methods of prepara-tion of nitrogen oxides have been discussed by L. Hackspill and J. Besson.G. Glockler gives a value 6-49 ev. (149-6 kcals./mole) for the heat of dissoci-ation of nitric oxide.The species involved in concentrated nitric acid and the evidence forions NO-, NO,+, H2N03+, etc., were discussed recently in these Reports.In addition to that, ultra-violet absorption of aqueous and anhydrous nitricacid in the range from 80HN03:20H20 to 76HN03:24N,0, has beenshown 8 to be consistent with the schemeZHO*NO, ,L 4 2 R 0 , 2N0,- + 2H30+X-Ray investigations 9 on crystalline (NO,*)(ClO,- ) have corroboratedRaman spectral results 10 and indicate a linear NO,+ ion.On the otherhand, W. R. Angus, R. W. Jones, and G. 0. Phillips have suggested l1 thatin liquid N205 and N204 respectively there is no necessity to postulateionisation but merely a state of polarisation NO,s+ - NO$-, NOS+ - NO,S-when, in the two cases, NO,+ and NO" are available but not present in thepure liquids. Thus electrolysis of N204 in glacial acetic acid between aniron cathode and a.platinum anode occurred only after addition of a crystalof sodium acetate. The reactions with sodium and liquid N204 and N,O,gave sodium nitrate and nitric oxide and nitrogen peroxide, respectively,indicating a t least the potential presence of the nitrosyl and nitronium ions.Liquid N20, as a solvent has also been considered by C. C. Addison and9* 0. Honigschmid and L. Johannsen-Grohling, 2. Naturforsch., 1946, 1, 656.2 S. H. Bauer, ibid., 1947, 69, 3104.3 J. S. Broadley and J. M. Robertson, Nature, 1'949, 164, 915.G. W. Watt, and C. W. Keenan, J . Amer. Chem. SOC., 1949,71, 3833.S. Classson, J. Donohue, and V. Schomaker, J . Chem. Physics, 1948, 16, 207.Bull. Soc. chim., 1949, 16, 479.J . Chem. Physics, 1948, 16, 604.Ann. Reports, 1947, 44, 74.R.N. Jones, G. D. Thorn, M. Lyne, and E. G. Taylor, Nature, 1947, 159, 163;E. G. Cox, G. A. Jeffrey, and M. R. Truter, Nature, 1948,162, 258.lo D. R. Goddard, E. D. Hughes, and C. K. Ingold, ibid., 1946, 158, 480.l1 Ibid., 1949, 184, 433.R. N. Jones, and G . D. Thorn, Canadian J . Res., 1949, 27, €3, 580104 INORGANIC CHEMISTRY.R. Thomson.12have suggested l3 an association between nitric acid and waterOther papers on the constitution of nitric acid solutionsHO-N \O rather than HO-N //O H- ... O>N-OH,/ O . . . H\O . . . H/or have considered l4 equilibria involving the ion pair H,O+*NO,- and thespecies (HNO,),NO,-. From a Raman spectral study the structure (VII)has been suggested l5 for the latter:\o..*H\o/ '0G.Jander and H. Wendt 16 have also used liquid anhydrous nitric acid asa solvent, in which phosphorus oxychloride, POCl,, undergoes solvolysis(POCl, + HNO, -3 HPO, + C1, + NOCl) and uranyl nitrate showsamphoteric character.J. R. Partington and A. L. Whynes have remeasured the vapour pressure 1'of nitrosyl chloride and studied its action la on various metals and theircompounds. Two new compounds, InCl,,NOCl and GaCl,,NOCl wereprepared.A low-temperature (450-900") preparation of phosphorus fromphosphates of bismuth, lead, and tin has been described. I?. E. Whitmore 2ohas shown that in the formation of 32P by neutron irradiation of sodiumsulphide, Na,3,S, the phosphorus practically all appears a s phosphate.Thus the recoiling phosphorus atom loses one or more electrons and is thusin oxidised form.Exchange of radio-phosphorus has been investigated 21between phosphorus trichloride and elementary phosphorus in carbondisulphide solution. The reactions and properties of the phosphorus sulphidesP,S,, P4S5, P4S,, and P4S,, have been discussed 22 as has the structure 23 of(PNCl,),. Evidence for the P-N ring structure of the last is presented.l2 J., 1949, S 211, S 218.l3 J. Ch6din and (Mme.) S. FQneant, Conzpt. rend., 1947,222,1424 ; J . Chim. physique,1948, 45, 66.l4 J. ChQdin, (Mme.) S. FhnBant, and R. Vandoni, Compt. rend., 1948, 226, 1722;J. ChBdin and R. Vandoni, ibid., 1948,227,1232 ; H. von Halban and M. Litmanowitwh.Helv. Chim. Acta, 1948, 31, 1963.15 J.ChBdin and (Mme.) S. FBnBant, Compt. rend., 1949, 228,242.Is 2. anorg. Chem., 1948, 257, 26 ; 1949, 258, 1 ; 259, 309.l7 J. R. Partington and A. L. Whynes, J . Physicui Coll. Chem., 1949, 53, 500.18 Idem, J., 1948, 1952.I@ P. Jolibois and J. C.Hutter, Compt. rend., 1949, 228, 1389.2O Nature, 1949, 164, 240.21 R. Muxart, 0. Chalvet, and P. Daudel, J . Chim. physique, 1949,46, 373.22 J. C. Pernet and J. H. Brown, Chem. Eng. News, 1949,27, 2143.23 H. Bode, Angew. Chent., 1948, 60, A , 67; see Quart. Reviews, 1949,3, 345DODD AND ROBINSON. 105The condensed phospha'tes have excited considerable interest recently,and the subject has been very thoroughly treated by B. T0pley.2~ It istherefore only necessary to mention papers which have appeared since on thethermal dissociation 24 of phosphoric acid and ammonium phosphates,the constitution 25 of Na3P30,, the X-ray structural examination 26 of(NH4),H2P20,, and the preparation 27 of the corresponding sodium salt byoxidation of red phosphorus with sodium chlorite.A critical literature survey 28 has been made-and experiments repeated-on the formation of solid hydrides of arsenic, antimony, and bismuth.The authors never obtained any solid h ydrides, whose existence they regardas still questionable.However, R. Nast 29 has prepared extremely unstableAs2H4 which debomposes at -100" to arsine and a red amorphous solid ofempirical formula ( A S ~ H ) ~ . Electrolytic oxidation of arsenic(II1) solutionshas given 30 no indication of a +4 oxidation state.The absorption spectraof mixed solutions of arsenic(II1) and arsenic(V) and of antimony(II1) andantimony(V) have been pl0tted.~1 The concentration dependence in thecase of antimony suggests the formation of an Sb(II1)-Sb(V) dimer. Hydro-lysis of [SbGCl,]- to [SbCl,(OH), -,]- apparently occurs, and H. Brintzinger 32assigns formuls Na[Sb(OH)6] and Na[Sb(OH),] to sodium antimonate andantimonite on the basis of dialysis experiments. Spectrophotornetric studieshave been made of complex ions present in bismuth thiocyanate 33 and bismuththiosulphate 34 solutions.The chemisorption of olefins on vanadium trioxide has been studied35in relation to the use of the oxide as a catalyst for hydrogenation. Com-pounds VC14N0, V,Cl,NO, and V2C1,(NO), have been all of whichsublime and yield vanadium tetrachloride and nitric oxide with water.A. G.Whittaker and D. M. Yost 37 have also investigated the dimerisation ofvanadium tetrachloride in carbon tetrachloride solution. Vapour pressuresof niobium and tantalum pentachloride and pentabromide and of tantalumiodide have been measured by K. M. Alexander and F. Fairbrother,38 who,incidentally, contest the name niobium and prefer columbium on historical24 H. N. Terem and (Mlle.) S . Akalan, Compt. rend., 1949, 228, 1437.25 E. Thulo and R. Ratz, 2. anorg. Chem., 1949, 258, 33.B6 B. Raistrick and E. Hobbs, Nature, 1949, 164, 113.2 7 E. Leininger and T. Chulski, J . Amer. Chem. Soc., 1949, 71, 2385.28 (Miss) C. Brink, G. Dallinga, and R. J. F. Nivard, Rec.Trav. chim., 1949, 68,29 Ber., 1948, 81, 271.31 J. E. Whitney and N. Davidson, ibid., p. 3809.32 2. anorg. Chem., 1948, 256, 98.34 F. Gallais and M. Brandela, Compt. rend., 1948, 226, 2148.35 V. I. Komarewsky and J. R. Coley, J . Amer. Chem. Soc., 1948, 70, 4163.36 A. G. Whittaker and D. M. Yost, ibid., 1949, 71, 3135.37 J . Chem. Physics, 1949, 17, 188.38 J., 1949, S 223 ; ibid., p. 2472 ; see also E. L. Wiseman and N. W. Gregory, J . Amer.234.W. M. Machevin and G. L. Martin, J, Amer. Chem. Soc., 1949, 71, 204.W. D. Kingery and D. N. Hume, J. Amer. Chem. SOC., 1949,71, 2393.Chem. SOC., 1949, 71, 2344106 INORGANIU OHEMISTRY.grounds. Complex fluorides of niobium and tantalum have been described,39as also a complex niobium sulphate,40 probablyK,Nb,I*1Nb"(OH)3(S04)6,9H,0.Group VI.-The interest in hydrogen peroxide continues.The thermalstability of concentrated hydrogen peroxide, in the range 50-100" and70-90% H202 by weight, has been recently studied 41 both in the presenceand in the absence of stabilisers. The preparation of Pyrex surfaces forreproducible results is a point of practical interest. W. F. K. Wynne-Jones 42has discussed the electrolytic properties of aqueous hydrogen peroxide, andM. G. Evans and N. UriP3 have remeasured the acid dissociation constantand the heat of dissociation, 2H,O, H30+ + H0,-. Their value of K(1.78 x 10-l2, &5%, at 20" and zero ionic strength) is more than twicethe value given by R. A. Joyner 44 (0.59-0-77 x 10-l2, at 0").Evans andUri's value of 8.2 kcals./mole for AH is in good agreement with Joyner'sdirect thermal measurement of 8-6 kcals. /mole. Electron affinities andsolvation energies for OH, O,H, O,, and 0,- are then calculated. Theproperties of the ion-pair complexes [ Fe( 0H)l2+, [ Fe( 0,H)l2 + areand differences in the absorption spectra discussed in terms of the electronaffinities of the OH and the 0,H radical. Such ion pairs, and the heat ofreaction 46 2Fe2+ + H,O, 2Fe3+ + 20H-, have considerable bearingon the iron(I1)- and iron(II1)-catalysed decomposition of hydrogen per~xide.~'Though there is general support for the basic Haber-Weiss mechanism,48V. S. Andersen49 has given experimental results which agree with themechanism Fe3+ + H0,- + [FeOHI2+ + 0, 0 + H0,- _I_, OH- + 0,.Uri 50 has investigated the effect of other ions on the peroxide decomposition,and the kinetics of the reaction between permanganate and hydrogenperoxide have been studied.51Variations as great as 2.5% and 5% respectively in the isotope abundanceratios 325 : 33S and 32S : 34S have been found 52 in sulphur from various sources.Generally, hydrogen sdphide in well wakers is low in the heavy isotope,and sulphates either in solution or as gypsum are enriched with the heavyisotope.This has been shown to occur even for sulphate and sulphide in thesame solution. The isotope 35S, produced artificially by the reaction39 G. S. Savchenko and I. V. Tananayev, J . Appl. Chem,. U.S.S.R., 1946, 19, 1093.4 O E. W. Golibersuch and R.C . Young, J . Amer. Chem. Soc., 1949, 71, 2402.4 1 W. C. Schumb, Ind. Eng. Chem., 1949, 41, 992.42 J . Chinz. physique, 1949, 46, 337.43 M. G. Evans and N. Uri, Trans. Paraday Soc., 1949,45,224.44 R. A. Joyner, 2. anorg. Chem., 1912,77, 103.45 M. G. Evans, P. George, and N. Uri, Tram. Faraday Soc., 1949, 45, 230.46 M. G. Evans, J. H. Baxendale, and N. Uri, ibid., p. 236.47 W. G. Barb, J. H. Baxendale, 9. George, and K. R. Hargrave, Nature, 1949,163,692; J. Weiss and C . W. Humphrey, ibid., p. 691; I. M. Kolthoff and A. I. Medalia,J . Amer. Chem. Soc., 1949, 71, 3777, 3784, 3789.413 Ann. Reports, 1947, 44, 65.50 J . Physical Coll. Chem., 1949, 53, 1070.61 (Mlle.) F. Fouinat, Compt. rend., 1949, 228, 1593.69 H. G. Thode, J. Macnamara and C.B. Collins, Canadian J . Bet?., 1949,27, B, 361.49 Acta Chem. Scad., 1948, 2, 1DODD AND ROBINSON. 10735Cl(n,p)35S, appears 53 in chemical form which exchanges rapidly withsulphate when potassium, sodium, and iron(II1) chlorides are used. A95-100% yield of 35S is obtainable as sulphate, but only with difficulty inany other form. V. Croatto and A. G. Maddock 54 have shown that use ofrubidium chloride gives sulphur which may be obtained in 50% yield ashydrogen sulphide by treatment with aqueous hydrochloric acid containinga trace of hydrogen sulphide as carrier.The molar magnetic susceptibility of diatomic sulphur has now beenmeasured 55 at temperatures of 550--850", and as in the paramagneticoxygen atom, agreement was found with the theoretical value for S, in the,I: state.The proportions of S, in sulphur vapour were shown to be satis-factorily predicted by existing equilibrium data. The solubility of hydrogensulphide in liquid sulphur from 120" to 455" shows 56 an increase withtemperature before falling near the boiling point of sulphur. Polysulphideformation was indicated, a maximum solubility of 0.19 g. of H,S per 100 g.of sulphur being observed. Raman spectra of hydrogen polysulphides havebeen measured 57 and their base-catalysed decomposition discussed 58 interms of structure. (Mme.) D. Peschanski 59 has given evidence that sulphurdoes not dissolve in sodium sulphide to a greater extent than corresponds toNa,S,. D. L. Douglas, F. Nesbitt, and D. M. Yost 60 have not been able toconfirm any exchange of sulphur (ass) between hydrogen sulphide and carbondisulphide in benzene solution after 95 hours at 120", though R.R. Edwards,F. Nesbitt, and A. K. Solomon 61 reported exchange between 35S2- inaqueous solution and carbon disulphide in separate phases.The reaction between hydrochloric acid and a saturated solution of S,N,yields 62 a reddish-brown precipitate which changes gradually to an equi-molar mixture of S,N,C1 and ammonium chloride; S,N,Cl may also beprepared by reaction between S,CI, and S,N,. On dissol-ving it in waterand treatment with potassium iodide, insoluble S4N31 may be precipitated.The lower oxides and oxyacids of sulphur have been further studied byM. G ~ e h r i n g . ~ ~ F. See1 and H. Bauer 64 have made conductivity measure-ments of solutions of acetyl chloride and nitrosyl chloride in liquid sulphurdioxide, wherein the cations CH,*CO+ and NOf appear to be formed.Thereaction SO, + SCI,-+ SOCI, + SO, has been investigated 65 by using35S as a tracer. C. A. Andresen and C. E. Miller 66 have described a simple63 M. B. Wilk, Canadian J. Res., 1949, 27, B, 475.54 Nature, 1949, 164, 613.5 5 A. B. Scott, J . Amer. Chem. Soc., 1949, 71, 3145.5 6 R. Fanelli, Ind. Eng. Chem., 1949, 41, 2031.5 7 F. Feh6r and M. Baudler, 2. anorg. Chem., 1949, 258, 132.5 8 0. FOSS, K . Norske Vidensk Selskab. Forh., 1946,19, No. 20, 72.5s Compt. rend., 1948, 227, 770.6o J . Amer. Chem. SOC., 1949, 71, 3237.62 A. G. MacDiarmid, Nature, 1949, 164, 1131.63 Angew.Chem., 1948, 60, A , 69.65 R . Muxart, P. Daudel, and B. Bosoardin, J . Chim. physique, 1949,46,466.66 J . Amer. P?&arm. ASSOC., 1948, 37, 204.61 Ibid., 1948, 70, 1670.64 2. Naturforsch., 1947, 2, B, 397108 INORGANIC CHEMISTRY.method of preparing sulphamide, SO,(NH,),, and the preparation and pro-perties of sulphur monofluoride have been recorded.67The system H,Se-Se-Na,CO, has been investigated by A. Pappas and M.Haissinsky,68 who have found polyselenides, Na2Se2, Na,Se,, Na,Se,,whose formation is independent of the allotropic state of the selenium.Further measurements 69 have been made and a mechanism suggested forthe photo-oxidation of hydrogen selenide in the presence of selenium. Thepreparation of pure strontium and calcium selenides has been described,70and their use as infra-red phosphors discussed.Selenium and telluriumin the +4 oxidation state have been studied 7 1 polarographically; noevidence was found for Se2 or Te2+.The salts Na,Se(S20,),,3H,0, K,Se(S,O,),,I QH,O, Na,Te(S,O,),, andK,Te(S,O,), have been prepared 72 as the first salts of seleno- and telluro-pentathionic acids. The equilibrium Se(S0,);- + 2S20,2- =+ Se(S,O,);- +2SO,,- is observed, whereas the corresponding reaction between sulphite andpentathionate, S(S,O,);- + 2S0,2- ---+ S(S0,);- + 2S2O,,-, goes to com-pletion. The sodium selenopentathionate crystallises in small shiny yellow-green leaves and is very soluble in water. The potassium salt forms yellow-green needles. In alkalinesolution both seleno- and telluro-salts are hydrolysed with precipitation ofselenium and tellurium.The intermediates Se( OH), and Te(OH), aresuggested. E'urther papers include discussion of a variety of reactions oftelluri~rn,~, the electro-chemical properties 74 of telluric acid, and thepreparation and properties 75 of tellurium tetraiodide.Chromium dioxide, which has been recently suggested 76 as an activeintermediate in the photochemical oxidation of glycerol by dichromate inaqueous solution, has been obtained 77 as an amorphous brownish-black solid,stable up to 400°, by heating chromium(II1) oxide in air above 320".The thermal dissociation of chromium(V1) oxide has been studied.78 Copperchromites have been prepared 79 and shown to be related according toThe salts are stable when dry or in acid solution.CuO + CuIICr,O, 2% Cu1,Cr,04 + [O].Thiochromites and selenochro-mites, M,CrSe,, of the alkali metals have been preparedand examined by X-rays.in high purity67 L. M. Dubnikov and N. I. Zorin, J. Gen. Chem. Ru~sia, 1947,17, 185.6s A. Pappas and M. Haissinsky, Bull. SOC. chim., 1949,16, 645.6g E. W. Pittman, J., 1949, 1811; see Ann. Reports, 1948,45, 107.70 A. L. Smith, R. D. Rosenstein, and R. Ward, J . Amer. Chem. Xoc., 1947,69, 1725.71 J. J. Lingane and L. W. Niedrach, ibid., 1949, 71, 196.7% 0. FOSS, Acta Chem. Scand., 1949, 3, 435, 708.'3 E. Montignie, Bull. SOC. chim., 1948, 15, 180; J. Mayer and M. Holowatyj, Ber.,7 5 E. Montignie, Ann. Pharm. franp., 1947, 5, 239.76 K.Weber and W. Asperger, J., 1948, 2119.7 7 (Mme.) M. DorninB-Berg&s, Compt. rend., 1949, 228, 1435.7% F. 3%. Vasenin, J. Gen. Chem. Moscow, 1947,17, 450.79 J. D. Stroupe, J . Amer. Chem. SOC., 1949, 71, 560.1948, 81, 119. 74 F. Fouasson, Ann. Chim., 1948, 3, 594.W. Rudorff, W. R. Ruston, and A. Scharhaufer, Act@ Cryst., 1948,1, 196DODD AND ROBINSON. 109An X-ray and chemical study 81 of molybdenum oxides in the rangeMOO,,.^^-^^^ has been made, and molybdenum-blue hydrates Mo401,,H,0and Mo,O,,H,O identified, among others. G. W. Watt and D. D. Davies 82have prepared anhydrous molybdenum(II1) oxide by reaction betweenMOO, and potassium dissolved in liquid ammonia. In 8-6 and &2N-hydrochloric acid, hexavalent and quinquevalent molybdenum have beenshown 83 to exist as [Mo0,I2+ and [M00]3+ in the stronger acid and LMoO,]~*+and [Mo0-j26* in the weaker acid.The heat of formation of tungsten(V1) oxide has been measured,s4 andthat of tungsten carbide recalculated. Tungsten trifluoride was obtained 85as a reddish-brown solid by reduction of tungsten hexafluoride with benzeneat 110" in a nickel bomb.The action of hydrogen fluoride on tungsten(1V)oxide gives, at 500", a grey solid, WOE',, chemically inert to boiling alkalisand aqua regia. A polarographic study s6 of tungsten has shown three forms,green, red, and yellow, of tungsten(III), and a deep red tungsten(IV), as wellas a 3.5 oxidation state.Group VB,--A comprehensive article by H. R. Leech 6' is now availableon the production, both technically and in the laboratory, of fluorine.E.Wicke 88 has reviewed the published values of the dissociation energyof the fluorine molecule, and from measurements of thermal conductivityof fluorine at 1000" gives a value for D(F,) = 63 kcals./mole, as generallyaccepted. A. D. Gaunt and R. F. Barrow 89 have, however, calculated avalue 50 rfr 6 kcals./mole on the basis of the ultra-violet absorption ofrubidium and casium fluorides. On the basis of thermodynamic propertiesof OF, and C1F calculated from electron-diffraction and spectroscopic data,R. L. Potter regards the best value as even lower, suggesting 1-5 ev. (34-6kcals./mole). Though rapid exchange o f chlorine between chlorine gas andhydrogen chloride occurs even in the dark, no similar exchange of fluorinebetween fluorine gas and hydrogen fluoride has been observed.91 This has beenadvanced as evidence for exchange of the higher halogens occurring throughan intermediate HX3.While there is no production of ozone observed whenfluorine is passed through water a t O", approximately 1% of ozone is pro-duced 92 on passing fluorine through sodium hydroxide solution a t -55".New reactions of the halogen fluorides have been discussed by H. J.Emel6~s.~3 Salts of the form KBrF,, AgBrF,, BaBr,Fs,94 and KIF, 95 haveAnionic forms were also present.B L 0. Glemser and (Frl.) G. Lutz, Angew. Chem., 1948,60, A , 69.83 A. R. Tourky and H. K. El Shamy, J., 1949, 140.84 G. Huff, E. Squitieri, and P. E. Snyder, J. Amer. Chem, SOC., 1948, 70, 3380.85 H.37. Priest and W. C. Schumb, ibid., p. 3378.86 J. J. Lingane and 1,. A. Small, ibid., 1949, 71, 973.13' Quart. Reviews, 1949, 3, 22.8s Nature, 1949, 164, 753.O1 H. W. Dodgen, W. F. Libby, ibid., p. 951.O2 E. Briner and R. Tolun, HeEv. Chim. Acta;, 1948,31, 937.Oa Angew. Chem., 1948, 60, A , 73.O4 A. G. Sharpe and H. J. EmelBus, J., 1948,2135.J . Arper. Chem. SOC., 1948, 70, 3751.8 8 Angew. Chem., 1948, 60, A , 65.O0 J . Chem. Physics, 1949, 17, 957.s5 Idem, J., 1949, 2206110 INORGANIC CEEMISTRY.been obtained; the existence of ions BrF,+ and BrF4- in liquid BrF, hasbeen post~lated.~~ Of particular interest is the actiong6 of iodine penta-fluoride on carbon tetraiodide and tetraiodoethylene. Compounds CIF,(b.p. -22.5"), in good yield, and C21F5 (b. p. 13") were obtained. Theseiodides do not form Grignard reagents under normal conditions but withmercury give CF3HgI and C,F5HgI. Ultra-violet irradiation of CF31in the presence of organic liquids indicates 97 the formation of CF, radicalswhich react with the solvent. The fluorination of methanol, or carbonmonoxide, in the presence of silver difluoride givesg8 a gas CF,*OF, withodour similar to fluorine, which liquefies to pale straw-coloured liquid at-95"; stable up to 450", it is a powerful oxidising agent. It did not provepossible to obtain CF,*OH by treatment with hydrogen.In a further contribution 99 on the photochemical reaction betweenhydrogen and chlorine, W. J. Kramers and L. A. Moignard have concludedthat the Nernst hypothesis must be modified and that chain inhibitorsare not completely destroyed by light.haveused radio-chlorine to study exchange between chlorine dioxide and chloride,chlorite, and chlorate ions.D. H. Derbyshire and W. A. Waters2 have shown that bromide-freehypobromous acid in mineral acid but not in approximately neutral solutionis very much more reactive as a brominating agent than free bromine. It issuggested that the hydrated bromine ion Br+,H,O is forined by HOBr + H+---+ (H,OBr)+.Further work on the nature of solutions of iodine is somewhat contra-dictory in character. N. E. Baylis has suggested that the spectra of iodineand bromine solutions can be adequately explained on the basis of thephysical properties of the solvent without postulating any special solute-solvent interaction.have found strong spectral evidence for an equilibrium I, + A + I,A,where A is the molecule of an aromatic hydrocarbon solvent molecule.No bands corresponding to the iodine-aromatic molecule interaction werefound for non-aromatic solvents.Spectrophotometric studies have suggested that no significant amountsof 12094- are present in periodic acid solutions but that species H,IO,-,H31062-, and H,I063- are involved.has been observed,6 the pyridinium salt of IC1,- being obtained and analysed.H.Taube and H. DodgenOn the other hand, H. A. Benesi and J. H. HildebrandThe reaction2SOC1, + 21- ---+ 2IC1,- + so, + s96 A. A. Banks, H. J. Emelbus, R. N. Haszeldine, and V.Kerrigan, J., 1948, 2188.97 R. N. Haszeldine and H. J. EmelBus, Research, 1948, 1, 715.98 K. B. Kellogg and G. H. Cady, J . Amer. Chem. SOC., 1948, 70, 3986.99 Trans. Paraday SOC., 1949, 45, 903.1 J . Amer. Chem. SOC., 1949, 71, 2501, 3330.8 Nature, 1949, 163, 764.Nature, 1949,164, 446; see C. N. Hinshelwood, J., 1947, 694.J. Amer. Chem. SOC., 1948,70,2832; 1949,71, 2703.C. E. Crouthamel, H. V. Meek, D. S. Martin, and C. V. Banks, i b a . , p. 3031.6 W. B. Brownell and L. C. ICing, ibid., p. 2926DODD AND ROBINSON. 111The reactions in the systems 12--N02-, 12-N3-, and Br2-N3- and the effecton them of thiosulphate and tetrathionate ions have been studied kinetically,and mechanisms have been pr~posed.~ The properties of astatine havebeen studied; the At- ion has been shown to exist in aqueous solution andat least two positive oxidation states have been observed.8The separation of technetium from molybdenum, from which it isproduced by proton bombardment, has been de~cribed.~ After precipitationof molybdenum with 8-hydroxyquinoline, the technetium is isolated byadsorption on copper sulphide produced by adding copper chloride andpassage of hydrogen sulphide. The per-rhena'tes of cobalt, nickel, man-ganese, and iron have again been prepared and described.1° Those of cobalt,nickel, and manganese confirm previous findings.Unusual colours in theiron salts suggest complex formation.Evidence has not been obtained for the rhenium oxyfluorides ReOF,and Re02F2 previously reported,llU but two new oxyfluorides ReOF, andRe02F3 have been prepared.l l b ReOF, is a cream-coloured crystalline solid,m. p. 3-;1.5", b. p. 55", liquid density 3.8 & 0.05 at 40°7 solid density 4.2 -& 0.05at the melting point. Re0,F3 is a pale yellow powder which begins to sinterat 90" and is liquid a t 95".Group VIII.-The ratio of isotopes in purified terrestrial and meteoriciron has been determined l2 by means of a mass spectrograph, and nodifference in proportion has been found either between different samplesof each variety or between the varieties themselves. The calculated atomicweight becomes 55.856 against the International value 55-85. Thermo-magnetic analysis has been used l3 to follow the decomposition 4Fe0-3Fe30, + Fe between 300" and 570".In this completely solid reaction,the effect of temperature of preparation, of composition, and of the presenceof Fe and l?e30, as centres of crystallisation has been studied. The solubilityof freshly precipitated " gelatinous " iron(II1) hydroxide has been measured 14and the vapour pressure and solubility of the hydrates of iron(I1) chloridehave been investigated.15 Evidence for the following equilibria has beenobtained l6 in the hydrolysis of iron(II1) chloride :2FeC12+ + 2H20 z+ [FeC1OHI22* + 2H+ZFe3+ + 2C1- + 2H20 + [FeCIOH]22+ + 2HC7 R. 0. GriEth and R. Irving, Trams. Faraday Xoc., 1949, 45, 305; G. Dodd and8 G. L. Johnson, R. F. Leininger, and E. Segrd, J . Chem. Physics, 1949,17, 1.10 W. T, Smith and G. E. Maxwell, J .Amer. Chem. Soc., 1949, 71, 578.l 1 (a) 0. Ruff and W. Kwasnik, 2. anorg. Chem., 1932, 209, 113; ( 6 ) E. E. Aynsley,l2 G. E. Valley and H. H. Anderson, J . Amer. Chem. Xoc., 1947, 69, 1871.l3 G. Chaudron and J. BBnard, Bull. SOC. chim., 1949, D, 117.lo U. R. Evans and M. J. Pryor, J., 1949, S 157.l5 H. Schsfer, 2. anorg. Chem., 1949,258,69.l8 H. Guiter, Bull. SOC. chim., 1948,15, 945.R. 0. Griffith ibid., p. 546; R. 0. GriEth and R. Irving, ibid., p. 563.E. Jacobi, Helv. Chim. Acta, 1948, 31, 2118.R. D. Peacock, and P. L. Robinson, unpublished results112 INORGANIC CHEMISTRY.and similar results have been obtained with chromium(II1) chloride. An-hydrous K,Fe(CO), and KHFe(CO), have been prepared,17 and the equili-brium constants K , = 4 x and K , = 4 x 10-l4 have been found forFe(CO),H, & He + Fe(CO),H- & 2H+ + Fe(CO),2-.Two papers de-scribe spectrometric studies of ferric thiocyanate. The first,18 discussingvarious isodielectric solvent pairs each of which had water in common, suggeststhat the species Fe,(CNS), and Fe(CNS)63- are responsible for the red colour,the former being the more intense. The second,lg relating to water with[Fe3+] : [CNS-] values ranging from 1 : 1 to 1 : 6, indicated that, in the range[Fe3+] = O.O143---0.0357~., species higher than FeCNS2+ occur and thatFe( CNS),+ preponderates in 0.5-1 M- solut ion.G. R. Hil120 has studied the oxidation of Co2+ by ozone, following thecourse of the reaction by absorption spectra of solutions of Co2+, Co1ITOH2+,and Co111Ac2+ in 0*2~-perchloric acid. A reinvestigation 21 of the familiarcolour change from pink to blue which takes place on the addition of hydrogenchloride to solutions of Co(I1) chloride has been made in ethyl alcohol-water mixtures, and it has been found that the stability of the blue increaseswith alcohol concentration and that the solution is decolorised by mercuricchloride through the formation of HgC1,2- ions. The Co(I1) complex[Co(H20)(CN),l3- is oxidised 22 by prolonged treatment with excess of alkalicyanide. The first two complexes are reduced by the dropping-mercuryelectrode to a Co(1) complex. Exchange between Co2+ and CO(NH&~+could not be detected and that between CO(NH,),~~ and CO(NH,),~+ wasvery s10w.23~24 The slow reaction C~*(en),,~ + C~(en),~+ Co(en),2T +C0*(en)~3+ has been carefully studied 25 in systems of known ionic strengths.The heat of activation is 15.1 kcals. and there is evidence that this includes anon-electrostatic component of appreciable magnitude.The solubility of N(OH), in dilute acid and base solutions shows it to be arelatively strong base.26 From the Raman spectrum of nickel carbonylthe long-accepted tetrahedral structure of the molecule has received furtherconfirmation.27 W. Hieber and R. Briick 28 have isolated a number of bi-nuclear nickel(1V) complexes one of which they have shown to be formedfrom the corresponding nickel(I1) complex by the disproportionation1 7 P. Knunholz and H. M. A. Stettiner, J. Amer. CJbem. Soc., 1949, 71, 3035.18 S. Baldwin and W. J. Svirbely, ibid., p. 3326.19 S. E. Polchlopek and J. H. Smith, ibid., p. 3280.20 Ibid., p. 2434.21 M. Bobtelsky and K. S. Spiegler, J., 1949, 143.22 D. N. Hume and I. M. Kolthoff, J. Amer. Chem. Soc., 1949,71, 867.S. A. Hoshowsky, 0. G. Holmes, and K. J. McCallum, Canadian J. Res., 1949,27, B, 258.24 K. J. McCallum and S. A. Hoshowsky, J. Chem. Physics, 1948, 16, 254.25 W. B. Lewis, C. D. Coryell, and J. W. Irving, J., 1949, S 386.2* K. H. Gayer and A. B. Garrett, J . Amer. Chem. SOC., 1949,71, 2973.27 B. L. Crawford and W. Horwitz, J. Chern. Physics, 1948,16, 147.28 Naturwiss.,. 1949, 36, 312DODD AND ROBINSON. 1132W1 -3 Nio + NiIV.forms nickel carbonyl :The change is induced by carbon monoxide, which4NiII(S,CS.+), + 4SH- + 8CO -+S(+.CS.S.),NiIV/ 'NP(S.CS.+), -+- 2Nio(CO), + 4+.CS.S-+ 2H2S.\S/The Ni2+ ion of nickel salts reacts 29 with potassamide in liquid ammoniaat -35.5" to give Ni(NH2),,2NH,. Thermal decomposition of this compounda t mm. pressure gives Ni(NH2), at 42-3", Ni3N, at 119*3", Ni3N a t 362",and the elements themselves a t 585". Further contributions to the eo-ordination compounds of platinum have been made by H. J. S. King30and by W. J. Lile and R. C. M[enzie~,~l and the study of tetramethylplatinumand trimethylplatinum tetramers has been continued.32R. S. Nyholm 33 has provided a useful up-to-date account of the stereo-chemistry of the Group VIII elements which includes a brief but adequateintroduction to the theoretical aspects of the subject.R. E. DODD.P. L. ROBINSON.G. W. Watt and D. D. Davies, J . Amer. Chene, Soc., 1948, 70, 3753.8o J., 1948, 1912.3x J., 1949, 1168.32 Ann. Reports, 1947, 44, 66; R. E. Rundle and E. J. Holman, J . Awae.r. Chem.33 Quart. Reviews, 1949, 3, 321.Soc., 1949, '41, 3264; G. Illuminati and R. E. Rundle, ibid., p. 3375

ISSN:0365-6217    

DOI:10.1039/AR9494600086

出版商:RSC    

年代:1949

数据来源: RSC

摘要:

ORGANIC CHEMISTRY.1. INTRODUCTION.THE present Report represents a first step towards implementing a newgeneral policy whereby Annual Reports are to revert to being balancedsurveys of the main lines of progress during the year they cover. The pastfifteen years, during which the Reports on Organic Chemistry were madeup of essay articles on special topics, have left a formidable leeway whichmust to some extent be made good. In the following Report an attempthas been made to deal with some of the more important topics which havenot been fully reviewed for some time and we have not tried to present atrue Annual Report, except in the section on “ General Methods ”; thetopics we have chosen for essay articles, in an attempt to cover some of themore important gaps, comprise “ Long-chain Aliphatic Compounds,”“ Vitamin-A and Related Polyenes,” “ Amino-acids,” “ Alkaloids,” “ Pro-teins,” and certain aspects of “ Theoretical Organic Chemistry,”The appearance during 1949 of what will surely come to be known asthe Penicillin Monograph presented us with a difficult problem.We haveregretfully concluded that the space allotted to us is quite insufficient toallow us adequately to summarise this enormous volume of work, out-standingly important though it is; fortunately the subject has been fullyreviewed elsewhere and the interested render is referred to the articlesby E. Chain2 and A. H. Cook3 and to the summarising chapters in theMonograph itself.It is hoped to present next year a Report which will deal with the majoradvances made in 1950, with references to relevant earlier work not pre-viously mentioned in Annual Reports; this will be supplemented by twoor three essay articles on special topics.Thereafter it should be possibleonce more to present true Annual Reports, although it will probably benecessary for several years to come to include a considerable number ofreferences to earlier work which was missed under the previous policy.A. W. J.H. N. R.2. THEORETICAL ORGANIC CHEMISTRY.Various topics bearing on the physical and theoretical aspects of organicchemistry have been reviewed in Annual Reports during the last few years,but an article specifically devoted to this subject has not been includedsince 1941. The present return to the earlier practice coincides with theH.T. Clarke, J. R. Johnson, and Sir Robert Robinson (Editors), “ The Chemistryof Penicillin,” Princeton Univ. Press, 1949.Ann. Reviews Biochem., 1948, 17, 651.Quarterly Reviews, 1948, 2, 203BRAUDE : THEORETICAL ORGANIC CHEMISTRY. 115establishment of a section headed I‘ Physical Organic Chemistry ” in theJournal and reflects the intense activity in this field.The problems of theoretical organic chemistry can still be summarisedunder the headings : (i) the detailed structure of organic compounds, (ii)the mechanism of organic reactions, and (iii) the correlation between structureand reactivity. These three themes are, of course, closely interwoven,but for this Report the aspect of mechanism has been chosen for specialemphasis. Apart from homolytic reactions, which have been fully reviewedrecently,l heterolytic substitution has continued to attract the largestamount of attention and it will be necessary? owing to limitations of space,to defer the discussion of other types of heterolytic reactions to a futureReport.Heterolyth Substitution.A. Nucleophilic substitution. 1. Replacementreactions of aZEyZ halides. The well-known work of E. D. Hughes andC. I(. Ingold and their collaborators in this field was reported in 1938and 1940 and has also been summarised by one of the authorsB2 It will berecalled that methyl halides undergo alkaline hydrolysis in aqueous solventsmainly by a second-order, bimolecular reaction (&2) between the halidemolecule and the hydroxyl ion, whereas tert.-butyl and other tertiaryhalides undergo hydrolysis mainly by a, first-order reaction, the rate ofwhich is almost independent of the alkali concentration.Hydrolyses ofsubstituted primary and of secondary halides exhibit mixed-order kineticsand the contribution of first- and second-order reactions can be determinedby studying the effect of alkali concentration, taking into account theaccompanying dehydrohalogenation (for a discussion of the eliminationreactions, see ref. 3). The first-order (solvolytic) reaction could arise froma one-stage bimolecular reaction between the halide and the solvent, orfrom a two-stage reaction, the first and rate-determining step of whichconsists of the ionisation of the carbon-halogen bond.The solvolyticreaction of simple primary and secondary halides is mainly a bimolecularreaction with the solvent, but for tertiary halides, and a-aryl-substituted(e.g., benzhydryl) halides powerful evidence has been adduced in favourof the two-stage mechanism.* Although it is recognised that electrostaticinteraction with solvent molecules plays an essential part in the ionisationand that the concentration of carbonium ions remains immeasurablyD. H. Hey, Ann. Reports, 1940,37,250; 1944,41, 181; 1948,45, 139.H. B. Watson, Ann. Reports, 1938, 35, 210; 1940, 37, 236; E. D. Hughes, Trans..Faraday Soc., 1941, 37, 603; J . , 1946, 968.E. D. Hughes and C. K. Ingold, Trans. Faraday SOC., 1941, 37, 657; M. L. Dhar,E. D. Hughes, C. K.Ingold, A. M. M. Mandour, G. A. Maw, and L. I. Woolf, J., 1948,2093.4 Cf. L. C. Bateman, M. C. Church, E. D. Hughes, C. K. Ingold, and N. A. Taher, J.,1940, 979; L. C. Bateman, E. D. Hughes, and C. K. Ingold, ibid., p. 1017; G. W.Beste and L. P. Hammett, J . Amer. Chem. SOC., 1940, 62, 2481.ti C. a. Swain and S. D. Ross, J . Amer. Chem. SOC., 1946,68,658; C . G. Swain, ibid.,1948, 70, 1119; C. G. Swain and R. W. Eddy, ibid., 1948, 70, 2989; of. P. D. Bartlettand R. W. Nebel, ibid., 1940,62, 1345116 ORGANIC CHEMISTRY.this mechanism has been termed unimolecular (&1) since only one moleculeundergoes covalency change in the rate-determining step. The precisenature of the solvation process has been the subject of much discussion;some fresh light has been thrown on this question by the work of C.G.Swain,5 who has shown that the reaction between triphenylmethyl chlorideand methanol in benzene exhibits third-order kinetics (second-order withrespect to methanol) and has suggested that solvolysis requires a concertedattack by two neutral molecules on the carbon and the halogen atom,respectively. Itl is found that in the a-methylated series, the rate constants(k,) of the second-order reaction in aqueous solvents vary in the sequenceMe>Et >Pri>But, while the rate constants (k,) of the first-order reactionvary in the sequence Me-Et-Pr<<But. The decrease in k, with increasinga-substitution is ascribed by Hughes et aL2 to the impedance of the approachof the negatively charged reagent by (i) increasing steric hindrance, and(ii) increasing electron-accession at the reacting carbon atom.The largeincrease in k, in the tertiary halides is ascribed wholly to the increasedelectron-accession which facilitates ionisation of the carbon-halogen bond.The reactivities of higher tertiary alkyl halides of the type CMe,R*Hal,where R = Me, Et, Pr, etc., reveal an irregular sequence of inductiveeffects Me < Et > Pri > Prn, which is also indicated in the primary andsecondary halides themselves.’M. Polanyi and his co-workers * have discussed the experimental resultsfrom the point of view of transition-state theory. In the bimolecularreaction, the entering group X, the carbon atom C at which substitutiontakes place, and the displaced group Y will be collinearly arranged, and thethree atoms attached to C will tend to be in a plane perpendicular to XCY,because this arrangement minimises the repulsion energies.In the caseof methyl halides, the activation energy will be practically equal to theenergy of stretching of the carbon-halogen bond to the transition statevalue, which is calculated to be of the order of 25 kcals./mol., and to decreasein the sequence MeCl > MeBr > MeI, in agreement with experiment. Whenthe a-hydrogen atoms are replaced by methyl groups, it is found that Xand Y approach more closely to the p-hydrogen atoms than the sum ofthe van der Waals radii. The resulting compression is of the order of 0.6 A.and causes a steric hindrance increment to the energy of activation, whichincreases with the number of a-methyl substituents and amounts to about2 kcals.in the case of But. Contrary to Hughes, Ingold, and their group,6 J. Shorter and Sir Cyril Hinshelwood, J., 1949, 2412; H. C. Brown and R. S.Fletcher, J . Amer. Chern. Soc., 1949, 71, 1845.7 I. Dostrovsky and E. D. Hughes, J., 1946, 157, 161, 164, 166, 169, 171;I. Dostrovsky, E. D. Hughes, and C. K. Ingold, J., 1946, 173; 1948, 1283; cf. Hughes,Quart. Reviews, 1948, 2, 107.8 E. C. Baughan, M. G. Evans, and M. Polanyi, Trans. Paraday SOC., 1941,37, 377;E. C. Baughan and M. Polanyi, ibid., p. 648; A. G. Evans and M. Polanyi, Nature,1942, 149, 608, 665; A. G. Evans, ibid., 1946, 157, 438; 158, 586; Trans. ParadayXoc., 1946, 42, 719; “ The Reactions of Organic Halides in Solution,” Manchester Univ.Press, 1946; A.G. Evans, M. G. Evans, and M. Polanyi, J., 1947, 658BRAUDE : THEORETICAL ORGANIC CHEMISTRY. 117Polanyi and his co-workers * regard the decrease in the rate of bimolecularsubstitution in the sequence Me > Et > Pri> But as due entirely to sterichindrance, particularly as the interpretation of the polar effect is ambiguous,since increased electron-accession a t the reaction centre will both repel thenegatively charged reagent and help to expel the replaceable group.Application of transition-state theory to the unimolecular reactionindicates that the activation energy should be practically the same as theendothermicity (&) of the ionisation reaction RHal+ R+ + Hal-, whereR+ and Hal- represent solwated ions.According to A. G. Evans,* thecalculated values of Q (in kcals./mol.) for aqueous solutions are MeCl 89,EtCl 59, Pr'Cl 37, and BuWl 26, the differences arising mainly from thedecreasing ionisation potentials of the alkyl groups. The observed valuefor the unimolecular solvolysis of BuWl in aqueous ethanol is 23 kcals./mo1.6%The complete change-over in mechanism with the tertiary halides is thusexplained by the fact that the energy of activation of the unimolecularreaction here falls below that of the bimolecular reaction.In a further group of papers by I. Dostrovsky and Hughes the principlespreviously established are extended in greater detail to the P-methylatedseries of methyl, ethyl, n-propyl, isobutyl, and neopentyl derivatives.Itis known from the work of F. C. Whitmore and his collaborators lo that theneopentyl halides are extraordinarily inert towards the usual nucleophilicreagents. This result is at first sight somewhat surprising, since neopentylis a primary group. Kinetic measurements show that the reactivity ofneopentyl halides is indeed extremely low when the XN2 mechanism isoperative (as is the case under the usual preparative conditions), but thatthe reactivity in solvolytic substitution is very similar to that of otherprimary halides.First- or second-order rate constants ( 104k) for substitution reactionsof RBr.7Reagent andOEt- in EtOH,I- in Me,CO,conditions. Mechanism. R = Me Me*CH, Me-CH,*CH, Me,CH*CH, Me,C*CH,95" ............S N 2 9650 647 181 26 0.006564" ............ S N 2 - 480 - - 0.02750% H,O-EtOH,95' ............ S N 2 + S N l 2.86 1.41 0.80 0.011 0.00995" ............ S,l f s ~ 2 0.017 0.027 0.018 - 0.015H20 in H*C02H,The alcoholysis with sodium ethoxide in dry ethanol, and the exchangereaction with sodium iodide in dry acetone, are of the second order for allthe primary halides, and the rate constants for the neopentyl derivativesare smaller by factors of 104--105 than those for the ethyl derivatives. Inaqueous ethanol, the first four members undergo much slower " neutral "@ E. D. Hughes, J., 1935, 255; K. A. Cooper and E. D. Hughes, J., 1937, 1183.lo F. C. Whitmore and C. H. Fleming, J . Amer. Chem. SOC., 1933, 55, 4161; F.C.Whitmore, E. L. Wittle, and A. H. Popkin, ibid., 1939, 61, 1586; P. D. Bartlett andL. J. Rosen, ibid., 1942, 64, 543118 ORGANIC CHEIXISTRY.hydrolysis by a bimolecular (though necessarily first-order) reaction withthe solvent, whereas neopentyl bromide undergoes somewhat faster hydrolysiswhich is insensitive to the addition of hydroxide ion but accelerated byincrease of the water content and ionising power of the medium. It isconcluded that the reaction of the neopentyl derivative is unimolecular underthose conditions, and this is supported by the observation that the accom-panying elimination reaction gives rise to tert. -amylene with rearrangementof the carbon skeleton, a phenomenon associated with the (at least partial)liberation of the positive carbonium ion.Finally, solvolysis in slightlyaqueous formic acid, a medium of still higher ionising power, is believed toproceed mainly by the X N l mechanism with all the primary halides, and herethe rate of reaction of the neopentylderivative is no longer abnormal, butquite comparable to that of the othermembers of the series. A practical out-come of these studies is that, with com-pounds which are sterically hindered inbimolecular substitution, reaction canoften be more readily effected by theaddition of a suitable solvent (e.g., water)than by the introduction of more power-ful reagents (e.g., hydroxide ion).Measurements a t different temper-atures show that the low reactivity ofthe neopentyl halides in bimolecularFIG.1. substitution is partly accounted for by!Z'rc~~ition state of neopeWl group in a relatively high energy of activation.bimoleculur substitution. 7 a i s thegen atoms. d, 0, and fare the @-carbon given a semi-quantitative interpretationof this result by developing the transition- atoms. The y-hydrogen atoms are .notshown.state theory due to Polanyi and hisschool.8 The transition state (see Fig. 1) is regarded as a resonance hybrid inwhich X and Y share one unit charge between them, and the distances YCand CX are equated to the sum of the covalent radius of carbon and the meanbetween the covalent and negative ionic (crystal) radii of X and Y. Theorientations of the atoms not directly bonded to C and normally subject tofree rotation are assumed to be such that the non-bonded distance whichfalls furthest below the corresponding van der Waals distance will be amaximum.It is found that two of the p-carbon atoms and four of they-hydrogen atoms approach X or Y more closely (by about 1 A.) than the" touching " distance and that the compressions are not very dependenton the size of X and Y (because XC and CY increase with the radii of X andY). Owing to the '' side-ways " approach of the reagent, the compressionin the transition state of the neopentyl group is thus considerably largerthan in the tert.-butyl group (see above), and, unlike the latter, exceeds thecritical value (ca. 0.8 A . ~ ) beyond which atomic repulsion forces inereasea-carbon atom, b Q& c are the a-hydro- Dostrovs1cy, Hughes, and Ingold ' havBRAUDE : THEORETICAL ORGANIC CHEMISTRY.119very rapidly. I n order to translate the geometrical compressions intoenergy terms, the interaction energy of two atoms is expressed in the formW = WE: + u', + Wr where WE represents the electrostatic energy (arisingfrom induced dipoles), WD the so-called dispersion energy (arising fromdipoles set up by molecular vibrations), and WI the interpenetration energy.The first two terms must be positive (attraction) and the last negative(repulsion), but neither the functions connecting the separate terms withthe non-bonded atomic distances, nor the constants governing their rela.tivemagnitudes are known with any certainty (cf. ref. 11). However, bymaking reasonable assumptions concerning these quantities and summing Wover all the non-bonded atoms concerned, upper limits to the contributions(A.Ew) of steric hindrance to the energy of activation can be calculated.The values thus derived indicate a relatively small steric effect up to thetert.-butyl group, but a strikingly large effect for the neopentyl group.R = Ma Et Pri Bui But neoPentylEexp.fOr RBr + OEt-inEtOH 20.0 21.0 - 22.8 - 26.2Eerp.for RBr + I- in acetoneor RBr + Br- in ethylenediacetate la ..................... - 19.0 19.8 - 22.6 25AE, experimental ............... - 1.0 1.8 2.8 4-6 6.2 (7.0)AEw, calculatad .................. - 1.9 1.9 2.3 2.7 12.6The values of AEw, particularly for the neopentyl group, are almost certainlytoo large, since the calculation neglects the bending of the XC and CYbonds induced by steric hindrance.Nevertheless, the semi-quantitativetreatment does explain how the interpolation of a CH, group in passingfrom the tert.-butyl to the neopentyl structure results in increased sterichindrance at the reaction centre. This result could hardly have beenpredicted from classical considerations and provides an excellent illustrationof the importance of the transition-state concept in the interpretation ofreaction mechanism.2. Replacement reactions 01 carboxylic esters. Next t o replacementreactions a t carbon-halogen bonds, those a t carbon-oxygen bonds are themost thoroughly investigated type of nucleophilic substitution. The usualmode of alkaline hydrolysis of carboxylic esters involves a bimolecularattack by the hydroxyl ion and acyl-oxygen fission (1).l3 Recent work byJ.Kenyon, M. P. Balfe, and their collaborators l4 has led to the recognitionof a second mode of hydrolysis which involves alkyl-oxygen fission. It isl1 F. H. Westheimer, J. Chem. Physics, 1947, 15, 252; D. H. R. Barton, J., 1948,12 L. J. le ROUX, C. S. Lu, S. Sugden, and R. H. K. Thomson, J., 1945, 586.340.H. B. Watson, Ann. Report.9, 1940,37,229; J. N. E. Day and C. K. Ingold, Trans.Paraday SOC., 1941, 37, 686.14 M. P. Balfe, H. W. J. Hills, J. Kenyon, H. Phillips, and B. C. Platt, J., 1942,556 ;M. P. Balfe, M. A. Doughty, J. Kenyon, and R. Poplett, ibid., p. 605; M. P. Balfe,E. A. W. Downer, A. A. Evans, J. Kenyon, R. Poplett, C. E. Searle, and A.L. Thrnoky,J., 1946, 797; M. P. Balfe, A. Evans, J. Kenyon, and K. N. Nandi, ibid., p. 803; M. P.Balfe, J. Kenyon, and R. Wicks, ibid., p. 807120 ORGANIC CHEMISTRY.found that the alkaline hydrolysis of esters derived from optically activesecondary carbinols R,R,C*H*OH, where R,, or R, and R,, are aryl oralkenyl groups, is accompanied by racemisation, the degree of which dependson R, and R,, and on the alkali concentration. Esters of this type alsoreact with methanol or ethanol to give the methyl or ethyl ethers, and withformic or acetic acid to give the racemic formates or acetates. The gradationof reactivity is illustrated in the table.(1.1 (11.)prepared by silver aceta$e dehydrogenation of decahydro-2 : 3-dipyridyl(IV) obtained by the dimerisation of l-piperidein.ll Hydrolysis of thetropane alkaloid, meteloidine, gives the base teloidine (V) which has beensynthesised by the condensation of mesotartaric dialdehyde, methyla*mine,and acetonedicarboxylic acid.1, C .Schopf and H. Stener 13 also havesynthesised the indole alkaloid, rutmarpine (VI), by condensation of o-amino benzaldeh yde with 4 : 5-dihydro-3 - car boline perchbra te .CH,* E. Anet, G. K, Hughes, and E. Ritchie, Nature, 1949,164, 501.ea Idem, ibid., 1950,165, 35.lo Nature, 1949, 163, 289.11 C. Schopf, A. Komzak, F. Braun, and E. Jacobi, Anden, 1948, 559, 1.12 C. Schopf and W. Arnold, ibid., 1947, 558, 109.13 Ibid., 1947, 558, 124.@ (Sir) R. Robinson, J., 1936, 1081JORNSON : ALKALOIDS. 197In the case of strychnine (XXXVII, p.207), R. B. Woodward l4 hasintroduced a novel concept into theories of alkaloid biogenesis. The earlieridea of G. Hahn l5 regarding the formation of the yohimbine alkaloids wasthat the nucleus (VII) could be built up by a preliminary Mannich-typecondensation of tryptamine and 3-hydroxyphenylacetaldehyde or itsequivalent, and a subsequent condensation with formaldehyde. If theinitial condensation occurred at the p-position of the indole nucleus, thenstarting from 3 : 4-dihydroxyphenylacetaldehyde (or its equivalent,3 : 4-dihydroxyphenylalanine) the product would be (VIII) and the 7-membered ether ring could be built up by a fission of the cateohol ring :-9 OHsulted$+d=&- -+ -C-O-C-&&-. The original should be con-OHfor the implications of these ideas and the several variants whichC? A--/I II It CH2\/\ /\ AI II\/ OH (VIII.) (VII.)were outlined.Sir Robert Robinson has commented favourably on thescheme and has assumed a similar fission of an aromatic nucleus to accountOMe OMeOH O M e L 7 CH, CH, ft$J,OMe/ / \ / \ / \/\/\ / \ /HO/\) E YHD CH H?’’B I II I CH,H,C N CHEtHN2 4CH2\/‘\ / \/’;)OHH,C\ AT\ /\//OHf c”fJ 11 ~ _______\dCH2 CH, CH, m.1 (X.)CH, CH,for the biogenesis of emetine.17 The condensation of norlaudanosine ofthe Winterstein-Trier hypothesis with formaldehyde or its equivalentwould lead to (IX) which, after oxidative degradation of one of the aromaticrings as shown, condensation with dihydroxyphenylalanine, and subsequentO-methylation, would give the accepted structure of emetine (X) ; the ethylgroup is derived by a reduction of the --CH2*CH0 group at some stage.Woodward points out that these possibilities of building up complicatedalkaloid molecules from plausible starting materials are so striking that i t isdifficult to believe that they lack significance.On the other hand, a recentl4 Nature, 1948, 162, 155.l5 Ber., 1934, 67, 2031 ; 1938,71, 2192 ; Annalen, 1935, 520, 123.l6 Nature, 1948, 162, 156. 1’ Ibid., p. 524198 ORGANIC CHEMISTRY.review l8 giving some of the biological background to the subject stressesthe need for caution when applying the information gained from syntheses"under physiological conditions " to events in vuivo, although it is verydifficult to accept the opinion of this author that such studies " have con-tributed little to a direct understanding of alkaloid biogenesis ."LeuccmoZ.---'J!his alkaloid, derived from Leucmna gZaueaBenthsm of the family Mimosaceze, has the formula C8Hl0O4N2 and appearst o be identical with mimosine 19920 from Mimosa pudiccr; L.The structure(XI) of leuczenol is based on the observations that pyrolysis gave 3 : 4-dihydroxypyridine,21s 22 degradative methylation gave S-methoxy- 1 -methyl-4-pyrid0ne,2~* 2* and oxidation with bromine gave ap-diaminopropionic acidhydrobr~mide,~~ thus proving thaf the alanine side chain was attachedthrough the nitrogen atom of the 3-hydroxy-4-pyridone ring and notthrough the 3-hydroxy group26 or a carbon atom of the nuc1e~s.l~ R.Adams and J.L. Johnson2' have described a simple synthesis of the(&)-alkaloid by the addition of 3-methoxy-4-pyridone to a-acetamido-acrylic acid, followed by hydrolysis of the product with hydrogen iodide.In the course of this work many novel reactions of the pyridones weredescribed .28Simple Bases.CH,/ \\ /NHj;'H2*CH(NH2)*C02H(XI.) (XII.) (XIII.)Conhydrine and $-Conhydrine.-Syntheses of conhydrine 29 (XII) and$-conhydrine 30, 31 (XIII) have been reported, the resolutions of the (&)-products being carried out with (+)-6 : 6'-dinitrodiphenic acid in everycase. The first30 of the two preparations of $-conhydrine was based on2-chloro-5-nitropyridine and used a malonic-type synthesis, and the secondstarted from a-picoline-5-sulphonic acid.31Cuscohygrine.-The structure of this compound (XIV) has now beenco CH2/ \H2Y p 3 2\ /HO*HV vH2/ \H0.G $HH2C CH*CHEt*OH H2C CH*CH,Et\JCH NHHC18 R.F. Dawson, Adv. Enzymology, 1948, 8, 203.19 D. Kostermans, Rec. Trav. chim., 1946, 65, 319; 1947, 66, 93.20 J. P. Wibaut, ibid., 1946, 65, 392.21 R. Adams et al., J . Amer. Chem. Soc., 1945, 67, 89; 1947, 69, 1806, 1810.22 A. F. Bickel, ibid., 1947, 69, 1805.s3 J. P. Wibaut et al., Rec. Trav. chim., 1946, 65, 6 5 ; 1947, 66, 24.24 A. F. Bickel, J . Amer. Chem. Soc., 1947,69, 1801.Z5 Idem, ibid., 1948, 70, 326.26 R. Adams and V. V. Jones, ibid., 1947, 69, 1803.28 R. Adams and V. V. Jones, ibid., p. 3826.Zs F. Galinovsky and H.Mulley, Monatsh., 1948, 79,426,30 W. Gruber and K. Schlogl, ibid., 1949, 80,499.81 L. Marion and W. F. Cockburn, J . Amner. Chem. SOC., 1949, 71, 3402.27 Ibid., 1949, 71, 705JORNSON : ALKALOIDS. 199established by two independent syntheses, one of which has been describedin the section dealing with syntheses under physiological conditions. Twoindependent groups of workers 321 33 have prepared cuscohygrine froml-methyl-2-pyrrylacetic acid by pyrolysis of a metallic salt to give 1 : 3-di-( 1 -methyl-2-pyrryl)acetone, and subsequent hydrogenation of the pyrrolerings. An earlier Russian claim 34 to have synthesised this alkaloid hasnot been confirmed.Lupinane Group.-Although the structure of sparteine (XV) was estab-lished in 1933 and confirmed by the synthesis of (&)-oxysparteine (10-CH, CH-CH, CH,H2(7---p32 H2(7--$=2 / 5 \ / \ 17\ P5\NMe B\ \12/H2C CH*CH,*CO*CH,*CH CH, H2v4 ‘YH >CH, yl‘ 14(iH3\ / H2C3 1N \nCH 13CH2 \ /NMe ‘66 ‘8H,-CH CH,(XIV.) (XV4ketosparteine) in 1936,35 it was not until last year that the reduction of theketo-group was successfully accomplished, and then the total synthesis ofsparteine was announced from no less than four different laboratories.G.R. Clemo, R. Raper, and W. F. Short 36 synthesised (-)-sparteine byreduction of (- )-oxysparteine with lithium aluminium hydride, and IF.Galinovsky and G. Kainz 37 have described the resolution of (k)-oxy-sparteine. The latter authors used an electrolytic method of reductiont o prepare (XV) either from (+)- or (-)-oxysparteine or from (&)-lo : 17-dioxy~parteine,~~ a method which was also used by E’.Sorm and B. Kei1.39In another approach,40 (&)-sparteine was isolated from the mixed productsof the hydrogenation of 4-keto-l-earbethoxy-3-2’-pyridylpyrido~oline(XVI) 35 over a copper chromite catalyst at 250”/350 atmospheres. (&)-Sparteine was resolved by means of (+)-p-camphorsulphonic acid,*l or lesssatisfactorily by ( -)-2 : 2’-dihydroxy- 1 : 1 ‘-dinaphthyl-3 : 3’-dicarboxylicacicL3739 E. Spath and H. Tuppy, Monatsh., 1948, 79, 119.33 H. Rapport and E. Jorgensen, J . Org. Chem., 1949, 13, 664.34 G. V. Lazur’evskii, Chem. Abs., 1941, 35, 4029.3B G. R. Clemo, W. MeG. Morgan, and R. Raper, J., 1936, 1025.36 J . , 1949, 663; Nature, 1948, 162, 296.38 G.Galinovsky and G. Kainz, ibid., 1947, 77, 137.3s Coll. Czechoslov. Chem. Comm., 1948, 13, 544; Chem. Abs., 1949, 43, 3828.40 N. J. Leonard and R. E. Beyler, J. Amer. Chem. Soc., 1948, 70,2298.41 Idem, ibid., 1949, 71, 757.37 Monatsh., 1949, 80, 112200 ORGANIC CHXMISTRY.The alkaloid rhombinine, isolated from Thermupsis rhombifoZia 42 andLupinus mcounii R ~ d b . , 4 ~ has been shown 44 to be identical with anagyrine(XVII) and with monol~pine.~~ Tetrahydrorhombinine is ( - )-lupaninewhich often occurs together with rhombinine.isoQuinoline Group.---Morp>hine. The considerable advances which havebeen made in synthetic analgesics have been the subject of comprehensiverecent reviews,Q6 and only some recent syntheses directed a t the morphinenucleus itself will be mentioned here.R. Grewe and his co-workers 47 havesynthesised the base N-methylmorphinan (XVIII; R = R' = H) by thecyclisation of 1 -benzyl-2-methyloctahydroisoquinoline (XIX ; R = R' = H)with phosphoric acid. Moreover by introduction of substituents into thebenzyl group, several analogues were prepared>* one of which, S-hydroxy-N-methylmorphinan was also synthesised by 0. Schnider and A. Griissner 49and found to have considerable analgesic activity. Grewe also showed thatthe action of concentrated hydrochloric acid on 1 -(3' : 4'-dimethoxybenzy1)-2-methyloctahydroisoquinoline (XIX ; R = R' = OMe) gave 4-hydroxy-3-methoxy-N-metbylmorphinan identical with ( -j- )-tetrahydrodeoxycodein(XVIII ; R = OH, R' = OMe).(-)-Tetrahydrodeoxycodein has beenobtained from dihydrothebainone and the (+)-form from sinomenin byClemmensen reduction. 50/ \ / \ / \ /H2f l'fy H2C 1 C /NMe H,C 1 CHR,C- -CH2 1 FW-I-CH~ I Hp-I-CN\ / \ /H2C CH2 H,C CH2\ / CH CH2(XIX.) (XX.)H2( 3 3 2(XVIII.)M. Gates and W. F. Newhall 51 have obtained an isomer of N-methyl-morphinan, identical with a by-product from the Grewe synthesis. 4-Cyanomethyl-1 : 2-naphthaquinone was treated with butadiene to give(XX) which by a series of reductions was converted into an oxygen-freebase and this after methylation gave the N-methylmorphinan isomer.4a R. H. F. Manske and L. Marion, Canadian J . Res., 1943, 21,B, 144.43 L. Marion, J . Amer. Chem. SOC., 1946, 68, 759.44 L.Marion and J. Quellet, ibid., 1948, 'SO, 3076.45 J. F. Couch, ibid., 1936, 58, 686; 1939, 61, 3327.MI F. Bergel and A. L. Morrison, Quart. Reviews, 1948, 2, 349; R. Grewe, Angew.67 R. Grewe and A. Mondon, Ber., 1948,71, 279.4* R. Grewe, A. Mondon, and E. Nolte, Annulen, 1949, 564, 161.49 Helv. Chim. Acta, 1949, 32, 821; Swiss P. 252,755; B.P. 620,258; Chem. Abs.,50 H. Kondo and E. Ochiai, Annuten, 1929,470,227; Ber., 1930,63,646.51 J . Amer. Chem. Soc,, 1948, 70, 2261; Experientia, 1949, 5, 285.Chem., 1947, A , 59, 194.1949, 43, 7517JOHNSON : ALKALOIDS. 201E. Schlittler and his co-workers 52 have reviewed and introduced somemodifications into certain of the methods of synthesis of benzylisoquinolines(XXI.) (XXII.)and aporphines.The same author 53 has re-examined the structure ofisothebaine on the basis of the Hofmann degradation and has confirmedthat the final product from the reactions is 3 : 4 : 5-trimethoxyphenanthrene,thus supporting the formula (XXI) of Gadamer and Klee.54 These con-clusions are not accepted by other workers.55Chelerythrine. -Furt her synthetic experiments, aimed at the Chelidoniumalkaloids, e.g., chelerythrine (XXII), have been described 56 and in par-ticular A. s. Bailey and Sir R. R~binson,~’ in a method which may welllead to the alkaloids themselves, have synthesised a dihydro- 1 : S-benzphen-anthridone containing the two necessary vicinal substituents in ring A.Daphnandra Alkuloids.-I. R. C. Bick and A. R. Todd 58 have establishedthat the Duphnundru alkaloids belong to the bisbenzylisoquinoline seriesand that sterically they are closely related to o~yacanthine.~~ Thusformula (XXIII) arid (XXIV) represent the group repandine (R = R’ = Me ;52536 5666158CH, .CH2\/\ 0 A/ll I I R”l,l II \/ \/ (XXIII.)RN\ /\$? /\A /NR’CH2 CH2VHCH2VHCH2H.&/ V N O M e 11 IOR” M e O f y \VH20/\/11 lf)Rtir 1-1 11 \/ \/ (XXIV.)HeEv. Chim. Acta, 1948, 31, 914, 1111; 1949, 32, 1880.Ibid., 1948, 31, 1119.V. V. Kiselev and R. A. Konovalovs, J . Gelz. Chem. Russia, 1949, IS, 148.H. S. Forrest, R. D. Haworth, A. R. Pinder, and T. S . Stevens, J., 1949, 1311.Nature, 1949, 164, 402; see also ibid., 1950,165, 235.J., 1948, 2170; 1949, 2767. 6e E. Sphth and J.Pikl, Ber., 1929,62,2251.Arch. PhQrm., 1914, 252, 247202 ORGANIC CHEMISTRY.R” = Me; R”’ = H), aromoline (R = R’ = Me; R” = H ; R”’ = H),daphnandrine (R or R’ = H; R‘ or R =r Me; R” = H; R”‘ = Me), anddaphnoline (R or R’ = H; R’ or R = Me; R” =r H ; R”’ = H). Tri-lohamine 6o is probably identical with daphnoline.Emetine.-Recent degradative experiments on the ipecacuanha alkaloidemetine 61 have established the structure (X) and a. scheme for its biogenesishas already been outlined l7 (p. 197). Several workers 62p 63 have subjectedemetine to Hofmann degradation, and M. Pailer 63 et al. established thatwith the rest of the molecule as in (X) ring D could be represented as (XXV),(XXVI), or (XXVII), of which (XXVI) was eliminated by their laterresults 64 and those of H.T. Openshaw et ~ 1 . ~ ~ Pailer isolated 4-methyl-3-ethylpyridine ( p-collidine) from the dehydrogenation of the hydrogenateddimethine base obtained by Hofmann degradation of N-methylemetineand thus provided direct evidence for the ethyl group in emetine. Exclud-ing the rather remote possibility of ring expansion in these reactions, wethus arrive a t structure (X) for the alkaloid.b CH, CH, b CH, CH,\ / \ / \ / \ \ / \ / \ / \C CH CH c CH CHCH, ‘ N ‘ hHEt AH: 4 = bHMe\ / \ /CH, CHMe\ / \ /CH, CH,(XXV.) - (XXVI. )CH,A. R. Battersby, H. T. Openshaw, and H. C. S. have proposedthe cyanine-like structure (XXVIII) for the anion of the red rubremetiniumsalts which were found to be obtained from emetine by mercuric acetateoxidation in acid solution.Such a structure seems to offer a better explan-6o H. Kondo and ,M. Tomita, Arch. Pharm., 1931, 269, 433; 1936, 274, 70; J .Pharm. Xoc. Japan, 1935, 55, 104.Review : M.-M. Janot, Bull. SOC. chim., 1949, 185.62 A. Ah1 and T. Reichstein, Hdv. Ohirn. Acta, 1944, 27, 366; A. R. Battersby andH. T. Openshaw, J., 1949, S 59.63 MoWsh., 1948, 78, 348; 1948, 79, 127, 331.6s Ezperientia, 1949, 5, 114.Ibid., 1949, 80, 94.The structure (X) has received further support fromlater degradative experiments by A. R. Battersby and HI. T. Openshaw, J., 1949, 3207JOHNSON : ALKALOIDS. 203ation of the properties of these compounds than does that of P. Karrer andhis co-workers,66 involving aromatisation of rings B and E.By similar Hofmann degradakions cephaelin has been shown to havethe structure (X) but with the 6-hydroxyl group ~nmethylated.~~Indole Group.Quinamine and Cinchonamine.-The interesting observ-ation that quinamine, one of the minor Cinchona alkaloids, produced2 : 3-dimethylindole on degradation, suggested that i t might contain anindole rather than a quinoline nucleus, in addition to the usual vinyl-quinuclidine group,6s and more recently,69 K. S. Kirby et al. have shownthat quinamine is isomerised to the yellow isoquinamine on treatment withalcoholic potassium hydroxide. Raymond-Hamet 7* has reported thatcinchonamine and aricine give colour reactions which indicate an indolenucleus. Sir R. Robinson in collaboration with Kirby has taken up thesubject of the structure of quinamine and in a preliminary statement 71they have shown that, on the basis of diazonium coupling reactions, quin-amine is not an aromatic indole; possibly it is a hydroindole but moreprobably a hydroquinoline compound.Yohimbine.-The accepted structure for yohimbine (XXIX) is a modific-ation by B.Witkop et aZ.72 of the earlier formula of C. Sch01z.~~ Yohimban,the basic ring system of yohimbine [i.e., (XXIX) without -OH and -CO,Megroups], has been prepared from yohimbine 7* and from the diastereoisomer,~orynanthine.~~ The structure of yohimbine was largely established onthe nature of its dehydrogenation products, yobyrin, ‘‘ tetrahydroyobyrin,”and “ ketoyobyrin,” which were obtained by J. P. Wibaut et aZ.76 by theaction of selenium on the alkaloid.The structures of all three compoundsare now known with certainty and have been confirmed by synthesis, ande 6 Helv. Chim. Acta, 1948, 31, 1219.87 M. Pailer and K. Porechinski, Monatiph., 1949, 80, 101.J., 1945, 524, 528.70 Compt. r e d . , 1941, 212, 135; 1945,220, 670; 221, 307.‘1 Festschrift P. Karrer, 1949, 40.6s J., 1949, 735.An important communication concerning thestructures of cinchonamine and quinamine has since been published (R. Goutard,M.-M. Janot, V. Prelog, and W. I. Taylor, Helv. Chim. Acta, 1950, 33, 150; see alsoW. I. Taylor, ibid., p. 164), in which degradative experiments are described leadingthe authors to propose the following structures for the alkaloids. Cinchonamine isobtainable from quinamine by lithium aluminium hydride reduction :CH2*CH2*OH+---Cinchonamine. Quinamine ( 9 )72 Annalen, 1943, 554, 83, 127.7 p J.Jost, ibid., 1949, 32, 1297.7 5 M.-M. Janot and R. Goutarel, Bull. Soc. chim., 1949, 509, 659.76 Rec. Trav. chirn., 1929, 48, 191; 1931, 50, 91; 1935, 54, 85.Helv. Chim. Acta, 1935,18, 923204 ORGANIC CHEMISTRY.it will be evident that the names, still widely used, applied to the last twoof these products, do not represent their true relation to yobyrin.CH,(XXIX.) ‘CbOH (XXX.)A substance having Witkop’s structure (XXX) 72 for yobyrin has beensynthesised by G. R. Clemo and G. A. Swan 77 and by P. L. Julian etwho also synthesised “ tetrahydroyobyrin ” or 2-(tetrahydro-3-isoquinolyl)-3-ethylindole (XXXI), the structure of which was established by Sch01z.~~An outstanding property of ketoyobyrin, the smallest fraction from thedehydrogenation of yohimbine, is the smooth cleavage by arnyl-alcoholicpotassium hydroxide to 2 : 3-dimethylbenzoic acid and norharman and onthis basis Witkop 72 proposed the structure (XXXII), which however didnot explain the neutral properties of the compound and did not correspondwith the observed spectral properties 79 which resembled those of rutaecarpine(VI).Moreover, the chemical behaviour of ketoyobyrin did not agree withthat of synthetic acylnorharmans.80 Another structure (XXXIII) wasadvanced by a number of workers 81% and by others 83% 84, who also describedthe synthesis of this compound. showedhow (XXXIII) would be expected to show the properties of ketoyobyrinand described the further dehydrogenation of (XXXIII) over palladium,giving (XXXIII; extra double bond a t C(5-61).It was also pointed outhow (XXXIII) removed any ambiguity concerning the position of the C(16)-carbomet hoxy -group of yohim bine.The syntheses of (XXXIII) followed the general method of Clemo andSwan 77 with modification~.~3~ s5 There were differences in the colour andcolour reactions of the ketoyobyrin obtained from yohimbine and thesynthetic product unless the latter was heated under reflux in xylene solutionwith Raney nickel. On the basis of this and the results obtained from the77 J., 1946, 617. ’* Raymond-Hamet, Compt. rend., 1945, 221, 387.*l R. B. Woodward and B.Witkop, J . Amer. Chem. Soc., 1948, 70, 2409.R. B. Woodward and B. Witkop78 J . Amer. Chem. Soc., 1948, 70, 180.R. Speitel and E. Schlittler, HeZv. Chim. Actu, 1949, 32, 860.Raymond-Hamet, Compt. rend., 1948, 226, 1379; M.-M. Janot and R. Goutarel,Ann. pharnz. frang., 1948, 6, 254.83 G. R. Clemo and G. A. Swan, J., 1949, 487; Nature, 1948,162, 693.P. L. Julian, W. J. Karpel, A. Magnani, and E. W. Meyer, J . Amer. Chem. Soc.,1948, 70, 2834; E. Schlittler and R. Speitel, Hdv. Chim. Acta, 1948, 31, 1199.so E. Schlittler and T. Allernann, ibid., p. 128JOHNSON : ALKALOIDS. 205lithium aluminium hydride reduction of ketoyobyrin, Swan 86 believes thatketoyobyrin is a mixture of (XXXIII) and its dehydrogenation product(XXXIII ; extra double bond at c(5-6)).CH,(40 Me(XXXII.)Witkop has given evidence for the trans junction of rings D and E ofyohiznbine and preliminary synthetic experiments aimed at the yohimbineskeleton have been rep~rted.~~g 888empervirine.-The important observation of V.Prelog 89 that dehydro-genation of sempervirine, a yellow alkaloid from Gelsemium sempervirensAit, with selenium a t 300” gave yobyrin (XXX), and with Raney nickel inboiling xylene gave tetrahydroyobyrin (XXXI), led him to propose structure(XXXIV) for the alkaloid. Syntheses of this structure 86~w have shown,however, that it is not that of the alkaloid. In order to account for thecolour of sempervirine, the absence of a free >NH group (infra-red spectrumand failure to form an amine oxide):’ its strong basic character, and theformation of (XXXI), it has since been formulated 92 as an anhydroniumbase (XXXV+XXXVI), and the metho-salts are held to be (XXXVI;Me group on the indole nitrogen) which accounts for the formation of N -methylyobyrin (synthesis from their selenium dehydrogenation.Thestructure of the salts was confirmed by an elegant synthesisQ4 from the86 J., 1949, 1720.87 J . Amer. Chem. Xoc., 1949, 71, 2559.88 P. L. Julian, A. Magnani, et al., ibid., 1948, 70, 174; 1949, 71, 3207.8s Ezperientia, 1948, 4, 24; Helv. Chim. Acta, 1948, 31, 588.0. E. Edwards and L. Marion, J . Amer. Chem. Soc., 1949, 71, 1694.B. Witkop, ibid., 1948, 70, 1424.92 R. B. Woodward and B. Witkop, ibid., 1949, 71, 379; R. Bentley and T. S.Stevens, Nature, 1949, 164, 141.P.L. Julian and H. C. Printy, J . Amer. Chem. Soc., 1949, 72, 3206.O4 R. B. Woodward and W. M. McLamore, ib&€., p. 380206 ORGANIC CIXEMISTRY.lithium derivative of N-methylharman and Z-isopropoxyrnethylenecycb-hexanone after acid treatment of the reaction mixture.Aspidospermine ; VuZZesine.-Aspidospermine, from the bark of Aspido-sperm quebracho and from the leaves of VaZZesia glabra, has been shown tobe an N-acetyldihydroindole derivative 95 and B. Witkop 96 has obtained3 : 5-diethylpyridine and an alkylindole by its degradation. Vallesine,also from Vallesia glabru, is apparently N-formyldeacetylaspidospermine 97(>N*CHO for >N.COMe).Strychnos Albaloids.1 (p. 5541 Strychnine and Brucine.-The involvedarguments which have resulted in the formula (XXXVII) for strychninecan be treated here only in a very abbreviated fashion. The whole fieldhas been surveyed by Sir R.Robinson in a Chemical Society lecture butthis has not yet been published.17 18\ / \ /CH, O*CH,(XXXVII.)\ / \ /CH2 O*CH,(XXXVIII.)The structure (XXXVII) has received independent confirmation fromthe detailed X-ray studies of C . Bokhoven, J. C . Schoone, and J. &I. Bijvoet 97*on certain strychnine salts, particularly the sulphate. An important seriesof oxidative degradations which were to a large measure responsible for themodification of the earlier Robinson strychnine formula 98 (XXXVIII)v5 H. T. Openshaw and G. F. Smith, Experientia, 1948, 4, 428 ; Ramond-Hmet,ss J .Amer. Chem. Soc., 1948, 70, 3712.v7 E. Schlittler and M. Rottenberg, Helv. Chim. Acta, 1948, 31, 446.v7a Proc. Koninkl. Nederland. Akad. Wetenschap., 1947, 50, 967; 1948, 51, 990;s8 J., 1939, 603.Conapt. rend., 1948, 226, 2154.1949,52, 120; Chem. Abs., 1948, 42, 4421 ; 1949, 43,4918, 5254JOHNSON : ALKALOIDS. 207were described with strychninonic acidQQ and showed that ring D must bea t least 6-membered :Icn- r; /&H ,&H\CHOi.e., n>3\ D / -+ cfl + c, co-co \CO*CO,H(XXXIX .)Confirmatory evidence was provided by studies of the lactamisation ofcuninecarboxylic acid.1 The alternative Swiss formula (XXXIX) forstrychnine could not be accepted 2s 3 for several reasons, principally becauseit did not provide an explanation of the properties of +strychnine (OH atC,,,,), now conveniently obtained by treatment of strychnine N-oxide withpotassium chromate solution a t lOO".* H.T. Openshaw and Sir R. Robin-son % s therefore advanced the present formula (XXXVII) as interpreting'' the whole behaviour of strychnine better than any other " although itdid not, a t that time, appear to offer a satisfactory explanation of theformation and properties of certain of the neostrychnine derivatives, e.g.methoxymethylchanodihydrostrychnone (XLI ; p. 210). On the otherhand it explained the formation of the most important products from drasticdegradations of strychnine, e.g., tryptamine, carbazole, and especiallyp-collidine. Moreover, it bore a biogenetic relation to the cinchoninemolecule which was even more apparent in another strychnine formula,6later rejected in the light of further experiments on the neo-derivatives,whereupon the authors reverted to the earlier formula (XXXVII).A morerecent scheme 14; p. ls7 for the biogenetic synthesis of strychnine has alreadybeen outlined (p. 197).An observation which gave insight into the mode of linkage of N(p) tothe indole ring came from a study of the properties of strychnone, anoxidation product of $-strychnine.8 R. B. Woodward, W. J. Brehm, and** V. Prelog and S. Szpilfogel, H e h . Chim. Acta, 1945, 28, 1669; Experielztia, 1945,1, 197.H. L. Holmes, H. T. Openshaw, and (Sir) R. Robinson, J., 1946, 908.(Sir) R. Robinson, Nature, 1946, 157, 438; Exparientia, 1946, 2, 28.V.Prelog and M. Kocbr, Helv. Chim. Acta, 1947, 30, 359.L. H. Briggs, H. T. Openshaw, and (Sir) R. Robinson, J., 1946, 903.* A. S. Bailey and ( S i r ) R. Robinson, J., 1948, 703.* (Sir) R. Robinson, Nature, 1947, 159, 263. ' R. N. Chakravarti and (Sir) R. Robinson, ibid., 1948,160, 18.* H. Leuchs, E. Tuschen and M. Mengelberg, Ber., 1944, 77, 408208 ORGANIC CHEMISTRY.A. L. Nelson9 showed that strychnone, on the basis of its absorptionspectrum, was not a dihydroindole as had been assumed, but a true indoleand formulated the reaction :CO\This deduction was accepted by A. S. Bailey and Sir R. Robinson lo whoarrived a t similar conclusions from a study of the analogous brucones.Treatment of methoxymethyldihydroneostrychnine l1 (XL) with diluteacids gave the neostrychninium salts which on pyrolysis yielded neo-strychnine isomeric with strychnine.neostrychnine is now more readilyobtained by treating strychnine with Raney nickel in boiling xylene,'. l2 andits structure (XXXVII ; double bond a t C(21-22) moved to C(20-21,) has beendeduced from its ready oxidation with bromine to give the aldehydicoxodihydroneostrychnine (renamed oxodihydroallostrychnine) : l3,CHO -N( @)*CH:C < + -N( @)CyPerbenzoic oxidation of methoxymethyldihydroneostrychnine (XL) gavemethoxymethylchanodihydrostrychnone (XLI) l4 which on Clemmensenreduction yielded methoxymethylchanodihydrostrychnane (XLII) l5 con-taining a C-methyl group. These reactions have been discussed in detailby R. B. Woodward and W. J.Brehm l6 who showed that the degradativeevidence could be satisfactorily explained onIy on the basis of formula(XXXVII) for strychnine. These authors devised a scheme whereby theformation of a new C-methyl group in (XLII) did not necessarily indicatea C-aldehydo-group in (XLI), vix., by reductive cleavage of the reactive* J . Amer. Chem. SOC., 1947, 69, 2250.11 0. Achmatowicz, G. R. Clemo, W. H. Perkin, and R. Robinson, J., 1932, 767.l* (Sir) R. Robinson and R. N. Chakravarti, J., 1947, 78.I* R. Robinson et at., J., 1934, 590; 1935, 936.l6 T. M. Reynolds and R. Robinson, J., 1934, 592.l6 J . Amer. Chem. Soc., 1948, 70, 2107.lo Nature, 1948, 161, 433.R. N. Chakravarti, K. H. Pausacker, and (Sir) R. Robinson, ibid., p. 1554JOHNSON : ALKALOIDS. 209p-ether grouping as shown, reduction of the crtrbonyl group to an alcoholand formation of a new ether as in (XLII).I n support of their theory,they found that a milder reduction of (XLI) by the action of Raney nickelon the corresponding diethyl mercaptal gave methoxymethyldeoxychano-dihydrostrychnone (XLIII) which contained no C-methyl group.CH,-CH,*OMe CH,---CH,*OMe ' CH--(i YH, YMeCH CH CHOI/ \\\-y-? c CH2D rnle CH CH CH\ /CH2H,--- CII2-- 9 3 2 HO,C 7 CO y" \ / \HY 'iH G\ / \ /7 (7H2 YMe R\--(i (iH2 TMeCH CH CH2 \/\ I II /CH CH CH, lrrMe / \ / \ / HO N \ / \ / \/\I 11N 4 /\/I (?H G\ / \ /OC CH CH OC CH CHICHMe, CH, O*CH, CH, O*CH,(XLIV.) (XLVT) (XLVI.)Vornicine.-The relation between vomicine, strychnine, and brucinehas been established lo by the formation of the same C17 acid (XLIV) bychromic acid oxidation of either N-methyl-sec.-$-strychnine,17 N-methyl-sec.-$-brucine, or vomicine, now formulated as (XLV) l8 on the basis ofthe extensive studies of H.Wieland and his colleague^.^^ The structureH. Leuchs, Ber., 1937, 70, 2455.K. H. Pausacker and (Sir) R. Robinson, J., 1948, 951.l9 R. Huisgen, H. Wieland and H. Eder, Annulen, 1949, 561, 193 and earlier papers;R. Huisgen, " Preparative Organic Chemistry," Part 11, 1948, p. 109; F.I.A.T.review of German Science, 1939-46210 ORGANIC CHEMISTRY.ofbeofvomip yrine(XLVI) bystrychnineobtained from a degradation of vomicine has been shown todirect synthesis,20 and the synthesised degradation productsnow cover the whole carbon-nitrogen skeleton with theexception of ring F.G. R.Clemo et aL21 have described some new reduction products ofstrychnine and have discussed the structures of their products and theirbearing on the nature of rings E and F. Support for ring E being 6-memberedhas come from its conversion into derivatives of 2 - ~ y r i d o n e , ~ , ~ ~ the workof V. Prelog, M. Kocbr, and W. I. Taylor 22 in this connection being partof an investigation 23 of new oxidative degradations of strychnine.AjmZine.-Further work has been reported 24 on the structure ofajmaline (the rauwolfine of L. van Italie and A. J. Steenhauer) 25 from theroots of RauwoEJia serpentinu Benth. Distillation of the alkaloid from zincgave carbazole and N-methylharman. Possible structures for the alkaloidwere suggested.Acridine Group.-The bark of Melicope fareanu F.Muell, from theQueensland rain-forest, contains the alkaloids melicopine, melicopidine,melicopicine, and acronycidine, the bark of Acronychia buueri also containsacronycine, and that of Evodia xanthoxyloides evoxanthine. These com-pounds were shown 26 to be derivatives of N-methylacridone, a ring systemwhich had not previously been found in the alkaloids. In a detailedinvestigation, W. D. Crow and J. R. Price 27 have determined the stmcturesof melicopine (XLVII), melicopidine (XLVIII), and rnelicopicine (XLIX) ,as well as several of the degradation products.(XLVII.) (XLVIII.) (XLIX.)Quinazolone Group.-The roots of the saxifrage, Dichroa febrifuga,Lour., contain alkaloids which are active antimalarials, two of which havebeen named febrifugine and isofebrifugine C16H,,03N3, and they appearto be 3-substituted 4-q~inazolones.~~ Both yield 4-quinazolone on per-manganate oxidation and are very susceptible to alkaline hydrolysis althoughthey are relatively stable to acids.Febrifugine is apparently dimorphic,and J. B. Koepfli et aZ.28 believe that the three dichroines of T. Q. Chou,2o (Sir) R. Robinson and A. M. Stephen, Nature, 1948,162, 177.21 J . , 1946, 891; 1948, 1661; Chem. and Id., 1948, 156.22 HeEv. Chim. Acta, 1949, 32, 1052.2* D. Mukherji, (Sir) R. Robinson, and E. Schlittler, Ezperientia, 1949, 5, 216.25 Arch. Pharm., 1932, 270, 313.es G.K. Hughes, F. N. Lahey, J. R. Price, and L. J. Webb, Nature, 1948,162,223.27 Austrdian J. Sci. Res., 1949, 2, 249, 255, 264, 272, 282.28 J. B. Koepfli, F. B. Mead, and J. A. Brockman, J . Amer. Chem. SOC., 1947, 69,25 Ibid., 1948, 31, 237, 505.1837; 1949,71, 1048TRACEY : PROTEINS. 21 1F. Y. Fu et ~ 1 . ~ 9 correspond to isofebrifugine and the two forms of febri-fugine, although the Chinese workers give Cl,H,lO,N, as the molecularformula. The isolation of these alkaloids has also been described by F. A.Kuehl, C. F. Spencer, and K. Folkers,30 their results being in essentialagreement with the otherDiscussion of severalpostponed.The chemistry of theAmerican workers.other important alkaloid groups has had to beA. W. J.8. PROTEINS.proteins has not been reviewed in these Reportssince 1937.l It is impossible therefore to refer to more than a fraction ofthe significant advances in our knowledge of this group of compounds thathave occurred since then, and this Report will therefore make special refer-ence to a single protein-p-lactoglobulin.This is a typical member of thecorpuscular class of proteins which behave in solution as though the ultimateparticles have no one dimension more than a few times as great as another.It is still possible to speak of their molecular weight as a property withsome meaning, and to estimate i t by chemical and physical methods. Theother class of proteins is that of the fibrous polymers in which particleweight in solution is more a reflection of the method of preparation than ofany intrinsic property of the compound.Myosin, a soluble, fibrous protein,has been recently the subject of a review in these Reports? tobacco mosaicvirus, also soluble, has been reviewed by N. W. Pi~-ie,~ and the insolublekeratin-collagen group by W. T. Astbury.* Many corpuscular proteins areknown but only a very few fibrous proteins. This is perhaps indicativeof their properties rather than of their distribution in living organisms.Corpuscular proteins are as a rule soluble and easily prepared whilst fibrousproteins tend not to be. The fibrous proteins that have been studied areall obvious subjects either because of their economic importance (keratinof wool, collagen of leather, silk fibroin, fibrous plant viruses) or of theiroutstanding theoretical importance (myosin of muscle).The distinctionmade between the two classes is useful but not absolute. Insulin, usuallyconsidered as a typical corpuscular protein, is readily and reversibly trans-formed into a fibrous state by extremes of P H , ~ and there is evidence thattobacco mosaic virus in the form usually investigated may be a linearpolymer of a corpuscular unit.6The last Report was written during the heyday of hypotheses regardingthe structure of proteins. In a textbook of 1938 ten hypotheses of protein25 Science, 1946, 103, 59; Nature, 1948, 161, 400; J . Anzer. Chem. Soc., 1948, 70,30 Ibid., 1948, 70,2091.1765.T. W. J. Taylor, Ann. Reports, 1937, 34, 302.3 Advances in Enzymobgy, 1945, 5, 1.I<. Bailey, ibid., 1946, 43, 280.Proc. Roy. Xoc., 1947, 33, 134, 303.F. C. Bawden and N. W. Pirie, Brit. J . Exp. Path., 1945, 26, 294.ti D. F. Waugh, J . Arner. Chenz. Soc., 1948, 70, 1850.’ ‘‘ The Chemistry of the Amino Acids and Proteins,” edited by C. L. A. Schmidt,Baltimore, 1938212 ORGANIC CHEMISTRY.structure were discussed of which seven commanded widespread assent.These were : (i) that proteins consist of a chain of amino-acids joined bythe peptide link (E. Fischer and F. Hofmeister), (ii) that apparent mathe-matical relations between the frequencies of amino-acid residuei calculatedfrom protein analyses were a reflection of a simple pattern of residues inthe polypeptide chain (M. Bergmann and C. Niemann), (iii) that isolatedproteins may represent variable fragments of ‘( protein supermolecules ”such as the total serum protein (W.B. Hardy and S. P. L. Sarrensen), (iv)that basic amino-acids are of particular importance in providing the ‘( founda-tion” of protein structure (R. J. Block), (v) that the molecular weightsof proteins fall in well-defined groups each a simple multiple of the smallestand that this reflects a principle of protein construction (T. Svedberg), (vi)that polypeptide chains are organised into three-dimensional lattices of afixed number of residues that supply the basis of Svedberg’s groups (D. M.Wrinch), and (vii) that the a- and the p-patterns found by the X-rayexamination of proteins are explicable in terms of two definite structures(Astbury).Of these it is fair to say that only the first stands unshakenapart from the mild caveat that there may be more than one polypeptidechain in a single molecule, whilst the last, after partial revision, is still thesubject of controversy. Little has replaced the missing hypotheses whichare now seen to have been based on oversimplification, inadequate or in-accurate evidence, or misinterpretation of the facts. Evidence is nowaccumulating that many proteins are built of a number of polypeptidechains linked together in a manner not definitely known. The search forunderlying regularities that inspired the hypotheses of Bergmann andNiemann, Block, and Svedberg was perhaps foredoomed by being carriedout at the organisational level of the total protein rather than at the levelof the constituent polypeptide chain.The Sarrensen hypothesis was basedin part on the observation that the solubilities of certain proteins believedto be pure did not obey the phase rule-possibly because they were in factnot pure, or because dissociation of a complex organised body of proteininto constituent proteins was occurring. It was the acceptance of the latterexplanation that led to A. Gronwald’s experiments,* which showed theheterogeneity of p-lactoglobulin, being ignored as evidence until theindependent demonstration by C. H. Li four years later.During the early 1930’s interest in the amino-acid analysis of proteinswas slight, perhaps owing to the tedium of pursuing the aim of a completeanalysis with methods known to be largely unsatisfactory.Consequentlythe proteins were examined in the main by physical methods. Greatadvances were made in the interpretation of titration curves and in techniquesof deriving information about the size and shape of molecules in solutionby the measurement of rate of sedimentation, sedimentation equilibria,rate of diffusion, viscosity, and electrophoretic and surface-film properties.In the present decade the study of the dielectric properties, electroviscousCompt. rend. Trav. Lab. Carlsberg, 1942, 24, 185.J . Amer. Chem. Xoc., 1946, 68, 2746TRACEY : PROTEINS. 213effects, and light scattering of proteins in solution has been added to themethods of investigation available, and repeated attempts to reconcile theoften conflicting results for degree of hydration and dissymmetry havebeen made.In the late 1930’s the delightfully simple hypotheses of Bergmann andNiemann attracted considerable attention.It was fortunate that thescanty analyses of proteins that were then available lent support to theirideas, for it was to the advantage of both the proponents and opponentsof the theory to produce more detailed, and above all, more accurate analyses.During the period under review the problems of determining the quantityand identity of amino-acids present in protein hydrolysates have largelybeen solved. In 1941 H. B. Vickery 10 reported that satisfactory methodsfor the determination of only nine amino-acids were known and that manyof these depended on quantitative isolation.The classical methods ofquantitative isolation were brought to their highest pitch a t this time byA. C. Chibnalf and his co-workers.ll The dicarboxylic acids and basicamino-acids were determined by their methods with an error of only 1-2%.At the time that the classical methods were reaching their peak, however,a number of new methods began to appear, relatively simple in executionand requiring little material. These included partition chromatography,12adaptable to both qualitative and quantitative requirements, micro-biological methods by which nearly all amino-acids may be determined bymeasuring the growth response of selected strains of moulds or bacteriato their presence, isotope dilution in which an isotope-containing amino-acid is added to the hydrolysate as a tracer, the isotopic-derivative method,and the use of specific enzymes. With these methods the determinationof the amino-acids present in a hydrolysate is now possible.Informationhas also been accumulated on the destruction of some amino-acids occurringduring hydrolysis. Thus an estimate may be made of the compositionof the material analysed. Whether or not this information is to be regardedas concerning the composition of a single, pure species of protein moleculeis to some extent a matter of taste. The interpretation depends entirelyon the weight given to the evidence available as to the purity of the proteins l3and indeed on the meaning of the word purity when applied to proteins.That the difficulty is real may be seen from the history of @-lactoglobulin.For long thought to be a homogeneous protein as judged on the basis ofsolubility, and behaviour in the ultracentrifuge and in electrophoresis, ithas been shown that although apparently homogeneous in the Tiseliusapparatus a t pH 5.3, 5.6,g and 8*3,lP it behaves as a mixture of three com-ponents a t pH 4-8 and 6 ~ 5 .~ T. L. McMeekin et aL1* recognised two mainlo Ann. New Yo& Acad. Sci., 1941,41, 87.l1 A. C. Chibnall, M. W. Rees, and E. F. Williams, Biochem. J., 1943, 37, 372.l2 Idem, Biochem. SOC. Symposia, 1949, 3.lS N. W. Pirie, BioE. Rev., 1940, 15, 377.T. L. McMeekin, B. D. Polis, E. S. DellaMonica, and J. H. Custor, J . Amer.Chem. Soc., 1948, 70, 881214 ORGANIC CHEMISTRY.components at pH 4.8,60% of one and 40% of the other. Moreover, theseworkers were able to separate the components partially, by recrystallisationfrom acetate buffer and by fractional precipitation with ethanol. Thefractions were shown to differ in solubility in water and O-O~M-N~CI. It ispossible that this heterogeneity may be due to no more than the combinationof one or two small molecules with charged groups on a portion of the mole-cules.Such a combination would be sufficient to result in electrophoreticinhomogeneity at some pH's and would be difficult to demonstrate byanalytical means.15p-Lactoglobulin.The preparation from whey of a crystalline globulin during an unsuccessfulattempt to obtain crystalline lactalbumin was reported by A.H. Palmerin 1934.16 The protein crystallised in two forms, needles and plates, theformer being unstable and changing slowly into the latter. The proteinappeared to be pure and was named lactoglobulin.Elementary Composition.-The total nitrogen content on an ash-free,dry basis was reported by Palmer as 15.3y0; subsequently values varyingfrom 14.35 to 15-62y0 were quoted. The work of A. C. Chibnall, 31. W.Rees, and E. F. Williams l7 on the determination of the total nitrogen ofproteins showed that erratic, low results may be obtained if anhydrousproteins are analysed, owing to their great hygroscopicity. Further errorsmay be ascribed to inadequate digestion times if the Kjeldahl method isused. The use of air-dry proteins of known water content and digestiontimes known to be adequate gives reproducible results. The value (15.58%)given by these workers agrees well with that of 15.60~0 obtained by themicro-Dumas method.ls Phosphorus and carbohydrates have not beenfound in p-lactoglobulin : sulphur contents of 1-60y0 1* and 1.680/, l9 havebeen found by the Pregl procedure.The difficulties of sulphur estimationin proteins with low sulphur contents have been underlined by the recentexperiences of C. A. Knight.20 41 analyses by 3 analysts of 13 preparationsof cucumber virus 4 gave values for the sulphur content of 0.07-1.26~0,with an average of 0.6y0. One analyst obtained values differing by 50%on the same preparation at different times. E. Brand and his co-workershave reported a total analysis of p-lactoglobulin : C, 53.39% ; H, 7.22% ;N, 15.60%; S, 1.60%; 0, 22.19% (by difference).21Amino-acid Composition.--In protein chemistry, determination of theproportions of constituent atoms is replaced in importance by determinationof functional groups of atoms (amino- and carboxyl groups, etc.) and con-1 5 T.L. McMeekin, B. D. Polis, E. s. DellaMonica, and J. H. Custer, J , Amer. Chem.16 J . Biol. Chern., 1934, 104, 359.18 E. Brand and B. Kassell, J . BioZ. Chem., 1942, 145, 365,l9 D. Bolling and R. J. Block, Arch. Biochem., 1943, 2, 93.2O J. Amer. Chem. Soc., 1949, '71, 3108.81 E. Brand, L. J. Saidel, W. H. Goldwater, B. Kassell, and F. J. Ryan, ibid.,Soc., 1949,7l, 3606.I7 Bwchem. J., 1943, 37, 354.1945,87, 1524TRBCEY : PROTEIXS. 216stituent groups of atoms-the amino-acid residues.Determination offunctional p u p s is usually carried out on the intact molecule, and will beconsidered later. Most amino-acids are determined in a protein hydrolysatethough some are determined on the intact protein. An analysis of p-lacto-globulin reported by Brand et aL21 is summarised in Table I. There aretwo striking points about this analysis, first the very high total of 99.13%of the protein accounted for and secondly that of the 26 estimations includedonly one is by isolation and no less than 10 rely on biological methods.TABLE I.The Composition of p-lactoglobulin.Amino-acid. Method. (a). ( b ) .Found, %.Glycine bact. 1 4 1.39Alanine bact. 6.2 7.09Valine bact.5.8 6-62Leucine mould, isotope diln. 15.6 16.5isoLeucine bact. 8.4 5.86Proline mould 4.1 5-14Phenylalanine bac t . 3.5 3.78Cystine absorp. 2.29 (2.29)Rlethionine iodometric 3-22 (3.22)Tryptophan ultra-violet 1.94 (1.94)Arginine absorp., isolation 2.88 2-91Histidine absorp. 1.58 1.63Lysine enz., isotope diln., bact. 11.4 12.58Aspartic acid bact., isotope diln. 11.4 11.52Clutamic acid bact. 19.5 19.08Amide-ammonia microdiffusion 1.31 (1.31)Threonine periodic acid oxidation 5.8 4.92Tyrosine absorp . 3.78 3.64116.33 11 1.49C ysteine absorp. 1.11 (1.11)Serine periodic acid oxidation 5-0 3-96Bact. : assay by growth response of suitable bacterium ; mould : assay by growthresponse of mutant Neurospora ; absorp. : absorptiometric method ; ultra-violet :ultra-violet absorption of tryptophan-mercury complex ; enz.: isolated bacterialdecarbox ylase.Column (a) are the results given in reference 21 ; the recovery on a residue basisis 99.13%. Column (6) gives the results of chromatographic analysis on starch columnsby Stein and Moore 27 ; the figures in parentheses are from column (a) and the totalof column ( b ) which includes these corresponds to a residue recovery of 97.7%The biological methods depend on the measurement of the growthresponse of a selected strain of bacteria or of a mutant mould to the presenceof an amino-acid which is the limiting factor to its growth in the mediumused. The amino-acid is added in known amounts at different levels tosome cultures and as aliquots of hydrolysate to others. Inaccuracies inthis method may arise from differences in response due to other substance216 ORGANIC CHEMISTRY.added in the hydrolysate which may either enhance or depress the growthresponse and also from the fact that usually only the L-isomer of amino-acids is utilised.If racemisation has occurred during hydrolysis low resultsfor the total amino-acid will result. The purity of the amino-acid used asstandard also requires attention. E. L. Smith and R. D. GreeneB found807% of isoleucine in P-lactoglubulin which agreed well with the value of8.4% found by Brand and his co-workers (Table I). Smith and Greene 23later found however that their standard had contained DL-iSoaZZoleucineand accordingly emended their value for isoleucine to 6.1%.The valuesfor amino-acids determined by the isotope-dilution method by G . L. Foster,which are those quoted by Brand in Table I, only refer to the L-isomer, forafter the addition of DL-isomer containing 15N to the hydrolysate, purificationwas directed towards the isolation of pure isomer.^* On the whole theevidence seems to be that racemisation in acid hydrolysis is not of greatimportance. A recent method for the analysis of protein hydrolysatesuses an isotopic reagent reacting quantitatively with the amino-acid to bedetermined.25 pIodobenzenesulphony1 chloride containing 1311 was thereagent used, and after completion of its reaction with the amino-acids inthe hydrolysate very large quantities of carrier (the p-iodobenzenesulphonylderivative of the amino-acid to be determined) were added.The derivativewas then isolated, if necessary in very low yield, and the isotopic dilutionmeasured. Co-precipitation in the isolation procedure must of course beavoided, but the enormous amounts of carrier that may be used permitrigorous purification. Either L- or D-amino-acids may be estimated, thecorresponding carrier being used. The glycine (1.56 %), alanine (7.05 yo) ,and proline (4-84y0) values found for a P-lactoglobulin hydrolysate arehigher than those obtained by Brand and his colleagues by biological methods.No D-alanine or D-proline was found ; 25 hydroxyproline was also absent.26Analysis by partition chromatography has also been applied to P-lacto-globulin hydrolysates.W. H. Stein and S. Moore 27 using starch columnsand fractional elution report the figures given in column ( b ) of Table I. Valuesfor the sulphur amino-acids are not given as the use of thiodiglycol as anantioxidant for methionine on the column had not been developed and thecysteine + cystine values found were known to be low owing to destructionduring hydrolysis. Similarly tryptophan was not found owing to loss onacid hydrolysis. The figures for threonine and serine have been correctedfor decomposition on hydrolysis by Rees’s factors.28 Using the values givenby Brand et aZ. for the missing amino-acids a 99.6% recovery of proteinnitrogen and 97.7% weight recovery was achieved. The hydrolysate fromonly 25-50 mg. of protein was sufficient for analysis in triplicate.It will22 J . BioE. Chem., 1947, 167, 833.24 Ibid., 1945, 159, 431.z5 A. S. Keston, S. Udenfriend, and R. K. Cannan, J . Anzer. Chem. Soc., 1949,26 Idem, quoted in ref. 27.g8 Biochem. J., 1946,40, 632.23 Idem, ibid., 1948, 172, 111.71, 249.27 J . Bwl. Chem., 1949,178, 79TRACEY : PROTEINS. 217be seen from Table I that the major differences between the chromato-graphic results and the earlier values are in those for alanine, isoleucine,proline, phenylalanine, lysine, serine, and threonine. It is known thatsome decomposition of serine, threonine,28 and phenylalanine 24 occurs onacid hydrolysis, the extent varying with the conditions. Stein and Moore’sresults for alanine and proline agree with those obtained by the isotope-derivative method whilst Brand’s high isoleucine value may be due to anunsatisfactory standard in the biological assay.23 Stein and Moore’s highlysine value may be due to a low biological value caused by racemisation,or to the presence of an unidentified compound travelling with lysine on thestarch column.No components other than those already known to bepresent were detected by chromatography. The recent work of J. R. Spiesand D. C. Chambers on the estimation of tryptophan, in which losses onacid and alkaline hydrolysis were followed, suggests that an upward revisionof the value in Table I is necessary. After alkaline hydrolysis 1.75y0 oftryptophan was found in a p-lactoglobulin hydrolysate by a colorimetricmethod and 1.84y0 by a biological method.29 By applying the colorimetricmethod to the intact protein a value of 2.57% was obtained.It will be clear from the previous discussion of some of the results recordedfor the composition of p-lactoglobulin, that though complete analyses ofproteins with almost theoretical nitrogen and weight recoveries are nowpossible the values for individual amino-acids are subject to error that insome instances may be considerable. This is especially so for amino-acidsthat may undergo decomposition on hydrolysis.Corrections may be madeon the basis of losses known to occur on treatment of the amino-acids underthe conditions of hydrolysis used. Unfortunately these model experimentsmay be misleading as the rate of destruction of an amino-acid may dependnot only on the other amino-acids or other substances present, but also onthe state of combination of the amino-acids.If tryptophan is heated inalkaline solution with cystine, cysteine, lanthionine, serine, or threoninesignificant losses occur.29 Twelve other amino-acids tested had no effect.Moreover, some amino-acids may protect tryptophan from destruction byserine. Nine amino-acids were tested, and protection varied from completewith-histidine and hydroxyproline to none with proline. Some of theseeffects apparently depended on whether the amino-acids were free orpeptide-linked.lklinhal Molecular Weight.-Minimal molecular weights of proteinsmay be calculated from the amino-acid composition. Good agreementwith results from physical measurements is usually obtained; in the caseof p-lactoglobulin the results are approximately equal ; in other proteinssuch as insulin the molecular weight observed by physical methods is amultiple of that calculated from analysis.The method depends to a greatextent upon the accuracy with which the percentage of the least abundantamino-acids has been determined.Estimation of Reactive Groups.-Further light can be thrown on theAltaZyt. Chem., 1949, 21, 1249218 ORaANIC CHXMISTRY.chemical composition of proteins by the examination of the reactive groupsin the intact protein. R. K. Cannan in 1938 30 briefly reported the presenceof 47 carboxyl groups per molecule of p-lactoglobulin (assumed, M 34,500)from an examination of its titration curve, and in a contribution 31 to thediscussion of another paper commented that a molecule of p-lactoglobulin(assumed M 39,000) appeared to contain 5 a-amino-groups. He suggestedthat these represented the free ends of five constituent polypeptide chains.Later results 32 gave an estimate of 57-60 carboxyl groups, 33-35 amino-(of which 29 were assigned to lysine), 6 glyoxaline, and 5-7 guanidino-groups per 40,000 g.of p-lactoglobulin. These results agree well with thoselater obtained by direct analysis. If the casboxyl ends of the polypeptidechain or chains are free, titration should reveal an excess of carboxyl groupsover those accountable for as dicarboxylic acids by analysis. A decisionon this point is rendered difficult by the large number of dicarboxylic residuesand the masking of some by amide formation.Published figures indicatean excess of 0-3. Figures for free a-amino-groups range from 5 (titration,32total amino-nitrogen less lysine nitrogen 339 21) to 3 (end-group assay 34).Chibnall,35 arguing on the basis of similar figures, suggests that a real deficitof carboxyl end groups could be explained by the polypeptide chains beinglinked by a union of a carboxyl group of one chain with a side group ofanother. The possibilities include (a) an ester link with serine, threonine,or tyrosine, ( b ) an imide link between C02H and CO*NH2, and ( b ) a thiolester link.and R’NH*CO*CH(NH,)*CH,*CH,*CO*NHR’’ involving dicarboxylic acidsand leaving a free a-amino-group do not occur in 8-lactoglobulin 36 or otherproteins3’ has been provided by the work of F.Haurowitz. He has alsoadvanced evidence for the existence of more than one residue of glutamicacid y-linked without free a-amino-groups in some proteins.3s The thiolester link is attractive in that it might be expected to be a weak link andto explain the appearance of thiol groups in proteins under conditions inwhich rupture of the -S-S- bond seems unlikely. The development ofa method by which a-carboxyl groups could be determined separately fromp- and y-carboxyl groups is obviously of great importance in the futureadvance of our knowledge of protein structure. The fact that proteinscan be shown to have free a-amino-groups does not enable any distinctionto be made between a structure of parallel chains held together by crosslinks (which would have an equal number of free a-carboxyl groups) andEvidence that imide links of the typeR’NH*CO*CH( NH2)*CH,.CH2*CO*NH*COR”30 Cold Spring Harb.Symp. p a n t . Biol., 1938, 8, 1.31 Idem, ibid., p. 17.32 R. K. Cannan, A. H. Palmer, and A. C. Kirbrick, J . Biol. Chern., 1942, 142, 803.33 S. R. Hoover, E. L. Kokes, and R. F. Peterson, Tezt. Res. J., 1948, 18, 423.34 R. R. Porter, Biochim. Biophys. Acta, 1948, 2, 105.35 Proc. Roy. Soc., 1943, B, 131, 136.36 F. Haurowitz and S. Tekman, Bull. Fac. wed. Istanbul, 1946, 9, 225.5’ F. Haurowitz and M. Tunca, Biochern. J., 1946, 39, 443.38 Haurowitz and F. Bursa, ibid., 1949, 44, 509W C E Y Z PROTEINS. 219one in which a number of chains are attached by their a-carboxyl groupsto a cyclic peptide (which would have no free carboxyl groups).It ispossible to demonstrate the absenee of amido-links between lysine amino-groups and carboxyl groups in many proteins.39 Cyclic peptides are known 4oand ovalbumin seems to have no free a-amino-group, which suggests acyclic structure.Our knowledge of the chemistry of a protein has only begun when itscomposition in terms of aminc-acids and reactive groups is known. Manyof the properties of a protein must depend not only on its amino-acid com-position but also on the arrangement of the residues within the molecule.The isolation and characterisation of peptides from partial hydrolysateshave been carried out sporadically since the work of Fischer in 1902 on silkfibroin.41 This work, much of it inconclusive, has been reviewed by R.L. M.Synge42 up to the advent of partition chromatography which gave it anew impetus. F. Sanger 39 has shown that it is possible to prepare proteinderivatives in which free amino-groups have been treated with l-fluoro-2 : 4-dinitrobenzene to form dinitrophenyl derivatives. The substituent is fairlystable to the conditions used in protein hydrolysis and it is possible to separatefrom the hydrolysate by chromatographic methods the dinitrophenyl-arnino-acids. Amino-acids which are a-substituted must be assumed tohave had free a-amino-groups, and therefore if they are monoamino-monocarboxylic acids to have been at the ends of chains.Application ofthis method has shown the presence of three terminal residues of leucinein p-lactoglobulin per 40,000 g.34 The terminal groups of other proteinsdetermined by this method are given in Table 11. If hydrolysis of dinitro-phenyl proteins is not carried to completion it is possible to isolate dinitro-phenyl peptides, in which the order of amino-acids can be established byfurther substitution and hydrolysis. Since peptides with an cc-amino-substituent must come from the end of a chain it is possible to work outthe order of residues, for a short distance from this point. In horse globin,which has six terminal valyl residues in a molecule of molecular weightabout 66,000, the chains are apparently not identical, for 2 : 4-dinitrophenyl-valyl-leucine, 2 : 4-dinitrophenylvalylglutamyl-leucine, and 2 : 4-dinitro-phenylvalylglutaminyl-leucine have been isolated from partial h ydrolysates.Similar methods led to the conclusion that the amino-acid sequences glycyl-isoleucylvalylglutamic acid and phenylalanylvalylaspartylglutamic acidoccur in insulin, the glycyl and phenylalanyl residues being terminal.43Further details of our knowledge of the structure of insulin are given inSanger’s review.44 His work on the splitting of the molecule into separatechains by oxidation with performic acid is of particular interest in that itprovides convincing evidence for the existence of inter-chain -S-S- bonds.This form of linkage has long been suggested, and more recently assumed,39 I?. Ssnger, Biochem.SOC. Symposia, 1949,3, 21.40 R. L. M. Synge, Quarterly Reviews, 1949, 3, 245.41 Chem. Ztg., 3902, 26, 939.43 Nature, 1948,162, 491.42 Chem. Reviews, 1943, 32, 135.44 Ann. Reports, 1940, 45, 203220 ORGANIC CHEMISTRY.Protein.InsulinHaemoglobin :HorseDonkeyHumancowSheepGoatMyoglobin :HorseWhaleEdes tinS-Lac toglobulinNativeDenaturedOvalbuminy-GlobulinSalmine(rabbit native)TABLE 11.Terminal Residues of Proteins.39Terminal residue.M ,assumed.12,00066,00066,00066,00066,00066,00066,00017,00017,000300,00040,000 --44,000170,0006,000to occur in many proteins.amino-acid.gl ycinephenylalaninevalinevalinevalinevalinemethioninevalinemethioninevalinemethionineglycinevalineglyeineleucineleucineleucinenonealanineprolineNO. ’permol.22665222222116133 -17No. of free No.of lysineamino-groupsof lysine.2 -404143474748---201950_L193219650residuesper rnol.2I39 - - --45 -I -1948.__-313120950In fact good evidence for its existence is atpresent confined to-insulin and wool.- The structure of wool keratin hasbeen investigated by A. J. P. Martin 45 and R. Consden and A. H. Gordon 46by the isolation of dipeptides from partial hydrolysates. Synthesis ofpeptides during acid hydrolysis is unlikely and has been shown not to occurin the hydrolysis of tyrocidin. Their results are of considerable theoreticalinterest in that the number of different amino-acids found to be linked withthe two basic am&o-acids indicates a very complex structure in whichsimple regularities may be hard to detect, and in that glutamylglutamicacid occurred in the greatest amount.Its high proportion in the productsisolated may be a result of the methods of isolation used but its existence inappreciable amounts is dficult to reconcile with the Bergmann-Niemannhypothesis and Astbury’s suggested structure for keratin (in which polarand non-polar residues alternate).Information on the relation of constituent parts of the protein moleculeis hard to get but some light is thrown on it by a study of protein denaturationand the steric hindrance to the reaction of large molecules with activegroups in some proteins.It has often been observed that the number ofdetectable thiol groups in proteins is increased by denaturation underconditions in which the rupture of an -S-S- bond is unlikely. The usualinterpretation of this phenomenon is that the reagents used in the detection45 “ Fibrous Proteins,” Bradford SOC. ; Dyers and Colourists, p. 1.4* Biochem. J., 1948, 43, xTRACEY : PROTEINS. 221of thiol groups cannot penetrate the interior of the closely knit structureof the native molecule while the disordering consequent on denaturationwould be expected to make groups accessible which were previouslyinaccessible. K. Linderstrsm-Lang and C. F. Jacobsen 4' have suggested,however, that thiol groups unapparent in native proteins are so, throughbeing involved in a thiazoline link with an adjacent amino-acid.They have7H2-SHR'NH*CO*CH=NH*C0.CHR2*NH*COR3 --+ p 3 2 - 7 R'NH.C0.CH.N:C*CHR2*NH*COR3shown that such a ring would be expected to be opened with the appearanceof free -SH groups under many of the conditions that lead to denaturation.Porter 34 has shown that some s-amino-groups of lysine in p-lactoglobulinand rabbit y-globulin do not react with l-fluoro-2 : 4-dinitrobenzene whenthe protein is native though they may after denaturation (Table 11).Keten will, however, react with all the s-amino-groups of p-lactoglobulin.It is suggested that this difference is connected with the difference in sizeof the two reagent molecules and hence with the ease with which theymay be presumed to penetrate the interstices of the structure of the nativeprotein.Purely chemical evidence leads to the following picture of the structureof P-lactoglobulin.It is composed entirely of amino-acids, eighteen innumber (cysteine, cystine, and the amides of aspartic and glutamic acidsbeing counted separately), linked by the peptide link. It is composed ofsub-units, each having a terminal leucyl group with free a-amino-group,joined by links probably not involving lysine &-amino- or carboxyl groupsin such a way that it is spatially compact and, whilst allowing the penetrationof small molecules, not permitting the entry of large molecules. Calculationsbased on the proportions of amino-acids present suggest a minimal molecularweight of about 40,000, implying the presence of about 350 amino-acidresidues per molecule.Much of the evidence leading to the statements inthis summary depends on the assumption that p-lactoglobulin is composedof a single molecular species. The only evidence suggesting that it is notis that of solubility and electrophoretic behaviour. It appears from therecent work of McMeekin et aE.15 that the combination of a substance withas few as two of the charged groups of p-lactoglobulin may alter significantlyits behaviour in these respects. It appears likely therefore that p-lacto-globulin may be pure by the chemical criteria that can so far be used.Further evidence regarding the structure of p-lactoglobulin has comefrom enzymic studies.The digestion of this protein by chymotrypsin andtrypsin has been studied by Linderstrsm-Lang and J a c o b ~ e n . ~ ~ Theappearance of titratable acid and base was used to estimate the numberof peptide links split, and the total volume change of the system wasmeasured a t intervals during the hydrolysis. The splitting of a peptide47 J . Biol. Chem., 1941, 137, 443.Compt. rend. Trav. Lab. Carisberg, 1941, 24, 1222 ORGANIC CHEMISTRY.link involves the creation of two new charged groups round which water ismore densely packed than in the body of the solution. This electrostrictioneffect can be measured in the splitting of simple peptides and has a valueof about 15 ml./mole. On theoretical grounds the contraction has a maxi-mum value of 25 ml./mole.In the digestion of clupein (a low molecular-weight protein of relatively simple composition) normal values of about15 ml./mole were found throughout the course of the hydrolysis. In theinitial stages of the digestion of native p-lactoglobulin by trypsin or chymo-trypsin abnormally high values were recorded-about 50 ml. /mole fortrypsin and 35 ml. /mole for chymotrypsin. When denatured p-lacto-globulin was the substrate the value was initially normal (20 ml./mole)but rose rapidly to a value of 35 ml./mole at a stage corresponding to thebreaking of 10 peptide links per molecule and then fell to a normal valueagain. These results cannot be interpreted on the assumption that onlypeptide links are being broken during the early stages of hydrolysis : theycan be explained on the assumption that the breaking of peptide bonds veryearly in the course of digestion renders the protein molecule unstable,leading to the spontaneous rupture of other bonds producing charged groupsnot detected by the methods of titration used.It appears unlikely thatruptured salt bonds would give rise to effects great enough to explainthe abnormal contractions observed. Further evidence that reactionsother than peptide-link rupture may occur during the hydrolysis of p-lacto-globulin was presented by G. Haugaard and R. N. Roberts who measuredheat evolution during its breakdown by pepsin.49 The heat evolved wasnot proportional to the number of peptide links split, and the evidencepointed to the existence of an exothermic non-hydrolytic process occurringduring hydrolysis.Dilatometric measurements were made during thedigestion of alkali-denatured p-lactoglobulin by pepsin and, in contrastwith the previous results48 with trypsin, there was no change in the valueof 24.2 ml./mole during the course of hydrolysis. The increase in dialysablenitrogen and nitrogen not precipitable by trichloroacetic acid (which werefound to be equivalent) was also followed. It was’of great interest that theratio of amino-nitrogen to total nitrogen in the dialysable and undialysablefractions did not change during the course of the enzyme action. It mustbe concluded that pepsin action on p-lactoglobulin is an “ all-or-none ”process and that its result is the rapid production of a definite number ofresistant fragments with no evidence of any intermediate stage.Alkalinedenaturation of the protein did not affect the constancy of the amino-nitrogenltotal nitrogen ratios of the dialysable and undialysable fraction.It did however affect their values, for the hydrolysis of native and denaturedp-lactoglobulin resulted in different end products. The rate of digestionof the native form is slower than that of the denatured protein but, sur-prisingly, the process is more complete. About 73 peptide links per mole-cule (M 40,000) are split when the native form is the substrate and 47 whenthis is the denatured form. Evidence for the “all-or-none ” action of49 J . Amer. Chem. Soc., 1942, 64, 2664TRACEY : PROTZTNS.223pepsin on egg albumin was obtained by A. Tiselius and I. B. Ericsson-&uensel,m who followed the course of hydrolysis by electrophoretic, sedi-mentation, and diffusion methods. They found only two components inthe digestion system - unaltered acid-denatured albumin and a fractionof average molecular weight of about 1,000 with no fragments ofintermediate size. Results of a similar nature have also been obtained byother w~rkers.~Oa, 50b BJ. A. V. Butler, E. C. Dodds, I). M. P. Phillips, and J. M. L.Stephen 519 52 have followed the course of hydrolysis of insulin by pepsinand chymotrypsin. In both there is a rapid reaction resulting in the pro-duction of small fragments of the molecule (when chymotrypsin is usedthere is also a large fragment, M about 4,000).During the rapid initialphase the relation between amino-nitrogen and non-protein nitrogen issimilar to that in the work of Haugaard and Roberts. The spontaneousformation of ‘‘ plastein ” which appears to occur in pepsin hydrolysatesof insulin without the mediation of pepsin or the formation of peptide linksmay be related to the exothermic non-hydrolytic process observed by theformer workers. Prolonged action of the enzymes was found to result inthe slow breakdown of the fragments rapidly formed initially. Explanationsof the results described postulate that the structure of the proteins con-cerned must be such that the breaking of a peptide link results in an inherentlyunstable residue which then either disrupts spontaneously or is much morereadily broken up by the enzyme.There are two difficulties in this view.First it implies subtleties in the chemical structure of the protein for whichwe have no other evidence, and the nature of which it is diflficult to imagine,and secondly these unknown factors must be unaffected by denaturationof the protein which is itself regarded as a loss of organisation in the structureof the protein. A simple postulate regarding the nature of the enzymemay be advanced that would explain the facts and involve no violence toour ideas of protein structure. It is supposed that action of an enzyme onits substrate is preceded by the attachment of an active area on the surfaceof the enzyme to the substrate, a t or near the point of attack.Followingthe completion of the attack the enzyme is then free to repeat the process.If the enzyme is multivalent in respect of its active areas then, when attack-ing a large polymer such as a protein, attachment to the substrate niayoccur in more than one site at once. Then after the breaking of the firstlink that of a second may follow a t once and so on. In effect this wouldmean that once the enzyme was within striking distance of the protein i twould not be free to leave it until all available and suitable bonds wereruptured. This explanation may be used also to cover the increaseddigestion of native p-lactoglobulin over the denatured form, since pre-sumably in the former susceptible links would be present in a smaller spaceBiochem.J., 1939, 33, 1752.50e 31. L. Petermann, J . Physica? Clzem., 1942, 46, 183.50b T. Winnick, J . Biol. Chem., 1944, 152, 465.61 Biochent. J . , 1948, 42, 116, 52 Idem, ibid., p. 122224 ORGANIU CHEMISTRY.than in the elongated denatured form. It would also imply that thedigestion of proteins would be a more rapid process than that of peptidessince there would be less ‘‘ lost time ” between the hydrolysis of successivelinks by individual enzyme molecules. J. H. Northrop, M. Kunitz, andR. M. Herriott 53 have commented that the rate of hydrolysis of syntheticsubstrates by pepsin is extremely slow compared to the rate of hydrolysisof proteins. i )Physical Evidence.-The survey of physical evidence for the structureof p-lactoglobulin will exclude that dealing with molecular shape andhydration in solution which has been summarised by J.L. Oncley.54 X-Raymeasurements by D. Crowfoot and D. Riley55 and by I. Fankuchen56agree in assigning dimensions of 110-111~. x 60a. x 62-63~. to the unitcell of air-dried P-lactoglobulin. The direct determinations of crystaldensity and hydration by T. L. McMeekin and R. C. Warner 57 indicatethat the molecular weight of the air-dried protein is 39,700, or 35,800 foranhydrous protein. Values for the wet crystal unit cell give a molecularweight of 61,000 or on a dry basis 33,000. Measurement of osmotic pressurealso gives results uncomplicated by hydration or shape in solution. Themeasurements of H. B. Bull and B. T. Currie 58 give a value of 35,050 (witha standard deviation of the mean of 144), whilst H.Gutfreund 59 found38,000 (with a standard error of 900). Some evidence for a slight increasein average molecular weight with ageing of the crystals was found by Bulland Currie who suggest that aggregation of a small number of moleculesmay occur. They quote in support of their value the results of W. Hellerand H. B. Klevens who found 35,000 & 1,OOO from light-scattering data.Study of monolayers of the protein on ammonium sulphate solutionsindicated that dissociation into two surface-active fragments with an averagemolecular weight of 17,000 occurs. I n the presence of Cut+, however,dissociation is suppressed or re-association occurs and the molecular weightbecomes 34,300. That re-association occurs is suggested by a greater areaof gaseous film per mg.of protein in the presence of Cu++. The measure-ments reported all lead to a molecular weight of about 35,000. Molecularweights calculated from analytical data (about 42,000) 359 21 and from ultra-centrifugal data (38,000--41,500) are considerably higher. Molecularweights from chemical data are unreliable unless the components ofp-lactoglobulin are identical in composition and size, and differ only in,for example, the order in which amino-acid residues occur. End-groupassays of sufficient accuracy would, if available, give an average molecularweight dependent on the number of molecules such as is given by osmoticpressure, film pressure, and X-ray data. Results from sedimentation58 I ‘ Crystalline Enzymes,” New York, 1948, p.73.54 E. J. Cohn and J. T. Edsall, “Proteins, Amino Acids and Peptides,” New55 Nature, 1938, 141, 521.67 Ibid., p. 2393.69 Nature, 1945, 155, 237.York, 1943, p. 563.66 J . Amer. Chem. Soc., 1942, 64, 2504.58 Ibid., 1946, 88, 742!I!RAC!EY : PROTEINS. 225equilibrium and sedimentation rate in relation to diffusion would be expectedto be higher since they are in the first case a weight average and in thesecond approach the weight average value. Denaturation of p-lacto-globulin in solution at pH 7 by heat has been studied by D. R. Briggs andR. There are two processes involved, the first of which begins a t65" and results in an approximate quadrupling of particle size with littlechange in mobility.The second, which occurs only after the first, willproceed a t temperatures below 65" and results in further particle-sizeincrease and increased mobility. Denaturation in the cold by urea (38%)has a negative temperature coefficient,61 being apparently reversed at 37".Synthetic Polypeptides.The intensive study of polymerisation reactions, stimulated by thedevelopment of new synthetic fibres and films, led in the period underreview to a re-awakening of interest in the preparation of synthetic poly-peptides. The H. Leuchs 62 method in which N-carboxyanhydrides ofamino-acids are polymerised in a moist atmosphere or in organic solventscontaining a trace of water or other catalyst has been widely employed.Y. Go and H. Tani 63 prepared the N-carboxyanhydrides of glycine, alanine,and leucine; on exposure to moist air, or on heating in pyridine a t loo",polymers of high molecular weight were formed with loss of carbon dioxide.A copolymer of glycine and leucine was also prepared.None of the productswas attacked by enzymes. R. B. Woodward and C. H. Schramm 64 usingthe same reaction prepared a copolymer of leucine and phenylalanine bypolymerisation in benzene containing a trace of water. They estimated,by viscosity measurements, the molecular weight of the product, which wasinsoluble in water, to be between 106 and 15 x lo6. C. J. Brown, D.Coleman, and A. C. Farthing 65 prepared the polymer by the same method,and found a molecular weight of about 15,000 for their product by end-group essay.A polylysine, prepared from the N-carboxyanhydride oflysine, in which the c-amino-group was blocked by forming the carbo-benzyloxy-derivative, was one of the first of these polymers to be thoroughlyinvestigated by chemical means (E. Katchalski, I. Grossfeld, and M.Frankel).66 A fraction of average chain length 32, as determined byestimation of free amino-nitrogen of the carbobenzyloxy-derivative, con-tained no free lysine, and gave a quantitative yield of lysine on hydrolysis.By the use of Sanger's l-fluoro-2 : 4-dinitrobenzene method it was shown tohave the expected ratio of a- to c-amino-groups. It was readily soluble inwater and appears to be the only polymer so far shown to be split byenzymes (glycerol extract of pancreatin, or crystalline trypsin).The6o J . Amer. Chem. Soc., 1945, 67, 2007.61 C. F. Jacobson and L. K. Cristensen, Nature, 1948,161, 30.62 Ber., 1906, 39, 857.64 J . Amer. Chem. Soc., 1947,69,1551.6s Nature, 1949,163, 834.Bull. Chem. SOC. Japan, 1939, 14, 510.$6 J . Amer. Ckm. Soc., 1947, 89, 2564.REP.-VOL. XLVI. 226 ORGANIC CHEMISTRY.method has been subsequently used for the preparation of polymerisedL-glutamic acid (y-carboxyl group shielded by methylation),67 glycine,sarcosine, DL-alanine, L-alanine, L-valine, m-leucine, L-leucine, D-leucine,DL-isoleucine, L-isoleucine, D -isoleucine, DL-norleucine, DL- a-phenylglycine,DL-phenylalanine, L-phenylalanine, L-tyrosine,68 and L-aspartic acid ( p-carboxyl group shielded by benzylation) .G9 Many copolymers have alsobeen prepared, and difficulty in the application of the reaction to prolinehas been reported.68 An interesting difference in water solubility of theDL-alanine polymer and the L-alanine polymer, the former being solublewhile the latter is insoluble, was noticed by Astbury et aZ.68Another method of synthesis has been used by Frankeland Iiat~halski.~~, 71Heating the ethyl or other esters of glycine and alanine (‘1 DL) in organicsolvents results in polymerisation with the release of the alcohol.Deter-minations of the average chain length indicated that products of 1 2 4 2units for glycine (110 if the methyl ester was used) and 10-23 units foralanine were attainable. The alanine polymers were soluble in waterwhilst the glycine polymers were not.This sudden wealth of synthetic polypeptides, many of which may beprepared in an orientated form, has naturally led to their examination byphysical methods in the hope that they will throw light on protein structure.S. E.Darmon and G. B. B. M. Sutherland examined the infra-red spectrumof Woodward and Schramm’s polymer and found it to be very similar tothat of denatured keratin in the region 1450 cm.11.72 Differences below thisfrequency are to be attributed to differences in residue and skeletalfrequencies. The infra-red spectrum of polyglutamic acid was found 67to be very similar to that of the remarkable natural polypeptide found inthe capsule of BaciZEus anthracis. This material was shown by G. Ivanovicsand V. Bruckner 73 to be largely composed of D-glutamic acid residues.W. E. Hanby and H. N. Rydon succeeded in isolating it in a relativelyundegraded condition and concluded that it was composed entirely of a-linked chains of D-glutamic acid which were in turn joined by y-peptidelinks.74 The presence of these latter unusual links was confirmed by Hauro-witz and Bursa.38 This material therefore provides an, at present unique,link between synthetic polypeptides and natural products for it seemsfeasible to construct from a-linked synthetic polyglutamic acid units ofsuitable chain length a closely analogous material.A preliminary examination of a number of amino-acid polymers byX-ray and infra-red techniques was published by Astbury et aZ. in 1948 : 68the majority of the compounds examined gave an X-ray pattern similar67 W. E. Hanby, S. G. Waley, and J. Watson, Nature, 1948, 161, 132.6 8 W. T. Astbury, C. E. Dalgliesh, S. E. Darmon, and G. B. B. M. Sutherland,O9 31. Frankel and A. Berger, ibid., 1949, 163, 213.70 Ibid., 1939, 144, 330.72 Ibid., 1947, 69, 2074.74 Biochem. J., 1946,40, 297.ibid., 162, 596.J . Amer. Cibem. SOC., 1942, 64, 2264, 2268.73 2. Immunats., 1938, 93, 119TRACEY : PROTEINS. 227to that of p-keratin ; D-leucine-DL-phenylahnine copolymer, however, gavea pattern resembling that of a-keratin as has been reported by Brown,Coleman, and Farthing.65 There are, however, differences in the patternthat have recently been re-emphasized by A s t b ~ r y . ~ ~ Attempts to convertthe a-pattern into a p-pattern were unsuccessful. Infra-red study of thepolymers showed that, as the confusion due to end groups normally foundon examination of simple peptides was absent, characteristic frequenciescould be assigned to individual residues. These enabled residues to beidentified in copolymers, and even in a protein (glycine, alanine, and tyrosinein silk fibroin). At higher frequencies evidence for the existence of at leasttwo distinct types of hydrogen bond in some polymers, such as are foundin some proteins and in nylon, was secured. Brown, Coleman, and Farthing 65on the basis of their observations on the leucine-phenylalanine copolymerwere led to suggest that the polypeptide chains run across the fibre axisin both the synthetic products examined and the natural a-proteins. Thissuggestion has been strongly opposed by Astburg 75 on the grounds thattheir suggested backbone spacing of 5.2 A. is impossible, as it cannot exceed4-77 9. Examination of the dichroism of frequency bands in the infra-redspectra of a- and p-keratin, myosin, and tropomyosin attributable to imino-groups in which hydrogen bonding occurs led E. J. Ambrose, A. Elliott,and R, B. Temple 76 to suggest an alternative structure for the a-fold inproteins to that proposed by A s t b ~ r y , ~ ~ This alternative structure involvesa repeating unit of two residues in place of the three suggested by Astbury.It will be seen that in this structure all the imino-hydrogen bonds are ofRone type and tend to be oriented in the direction of the chain. This orient-ation is suggested by the dichroism of the frequency bands. A s t b ~ r y , ~ ~however, points out that such a structure would only give a strong meridionalreflection of about 5.1 A., such as is found, if light and heavy side chainsalways alternated along the chain, a supposition for which there is noevidence. Furthermore, interpretation of the 100 yo extension of keratinand myosin is not easy on this model. Darmon and Sutherland point outthat the proposed structure allows for only one type of hydrogen bondwhereas there is evidence for the existence of a t least two or three typesof NH . . . OC bonds in proteins, and that too great reliance on present inter-pretations of imino-bond dichroism is hazardous. 78 Support for the views7 5 Nature, 1949, 164, 439.7 7 Chem. and id., 1941,60,491.?8 Ibid., 163, 859.7 * Nature, 1949, 164, 440228 ORGANIC CHEMISTRY.of Ambrose and his co-workers has recently come from S. Mizushima, T.Simanouti, M. Tsuboi, T. Sugita, and E. Kato 79 who had arrived at similarconclusions independently. M. V. T.R. E. BOWMAN.E. A. BRAUDE.A. W. JOHNSON.H. N. RYDON.M. V. TEACEY.7O Nature, 1949, 164, 918

ISSN:0365-6217    

DOI:10.1039/AR9494600114

出版商:RSC    

年代:1949

数据来源: RSC

摘要:

BIOCHEMISTRY.1. INTRODUCTIION.UNDOUBTEDLY the most important biochemical event occurring during 1949was the holding of the First International Congress of Biochemistry inCambridge under the Presidency of Prof. A. C. Chibnall, F.R.S. TheCongress was attended by more than 1700 members representing 42 differentcountries and resulted in the setting up of an International Committee forBiochemistry under the Chairmanship of Sir Charles Harington, F.R.S.,with Prof. K. Linderstram-Lang as Secretary. An approach is being madeto the International Council of Scientific Unions with a request for therecognition of this Conunittee as the international body representative ofbiochemistry and with a view to the formal constitution of an InternationalUnion of Biochemistry, as soon as possible.The subject of Biochemistry has therefore reached another and Significantstage in its development as an independent scientific discipline.The work of the Congress was spread over 12 sections and a volume ofabstracts of communications was issued to each participating member.In selecting topics for this year's Report, attention has been directedto fields in which notable advances have been recorded during the year.These must necessarily be reviewed against the background of previousdiscovery and interpretation, but it is felt that, in the fields both of thecarotenoid pigments and of the hx?mopoietic factors, very significant advanceshave been achieved during 1949.c. R.2. HBMOPOIIETIC FACTORS.(FOLIC ACID AND VITAMIN 1312.)In this short review i t will be possible to mention only a small selectionof the many important papers on haemopoietic factors published within thelast four years.Folic Acid.-This subject-was last reviewed in Annual Reports for 1946,since when a very great deal of work has been produced.The literaturehas been reviewed ls2 up till 1949. Much of the difliculty met in earlywork on this subject was due to the fact that a number of closelyrelated compounds had folic acid activity for different organisms. Thetable gives the main factors shown to be members of the folic acidgroup.1 T. H. Jukes and E. L. R. Stokstad, Physiol. Reviews, 1948, 28, 51.E. L. R. Stokstad and T. H. Jukes, Ann. Reviews Biochem., L949, 18, 435230 BIOCHEMISTRY.(Adapted from T.H. Jukes and E. L. R. Stokstad.l)Factor. Source and effects. -Vitamin M.Factor U.Vitamin B,.Norite eluate factors.Folic acid.L. casei factor.Vitamin B,, and B,,,Factors R and S.Yeast extract, effective in tropical sprue.3Yeast and liver extract effective in nutritional cytopenia of theYeast extract, promoted growth in chicks.6Adsorbed on fullers' earth, prevented nutritional anaemia in theFrom yeast and liver, promoted growth of L. m ~ e i . ~Active for S. fmcaZis R, prepared from spinach.8Prepared from liver and yeast.'Promoted growth and feathering of chicks.'*Essential in chick nutrition.llmonkey.'chick.8The chemistry of these compounds has been investigated 12. l3 and toconform with these findings they are considered as derivatives of pteroicacid (I), folic acid (liver L.cusei factor) being pteroylglutamic acid (PGA)(11). I n pteroyltriglutamic acid two further mglutamic acid molecules(1.1 OHare attached by y-peptide linkages to the glutamic acid residue of pteroyl-glutamic acid, and in pteroylheptaglutamic acid (Vitamin B, conjugate)six ngfutamic acid molecules are attached by y-peptide linkages to theglutamic acid residue of PGA.Deficiency states which may be controlled by the administration of PGAhave been produced in a number of animals and insects, e.g., rat,l* guinea-s L. Wills, Brit. Med. J., 1931, I, 1059.4 P. L. Day, W. C. Langston, and W. J. Darby, Proc. SOC. Exp. BioZ. Med., 1935,ii E. L. R. Stoketad and P. D. V. Manning, J.BioZ. Chem., 1938,125,687.(I A. H. Gogan and E. M. Parrott, ibid., 1939,128, xlvi.38, 860.E. E. Snell and W. H. Peterson, J. Bact., 1940,39, 273.H. K. Mitchell, E. E. Snell, and R. J. Williams, J. Amer. Chem. Soc., 1941, 83,2284.* E. L. R. Stokstad, J. Bid. Chem., 1943,149, 573.lo G. M. Briggs, T. D. Luckey, C. A. Elvehjem, and E. B. Hart, ibid., 1943,148, 163.l1 A. E. Schumacher, G. F. Heuser, and L. C. Norris, ibid., 1940,135, 313.l2 5. H. Mowat, B. L. Hutchings, R. B. Angier, E. L. R. Stokstad, J. H. Boothe,C. W. Waller, J. Scmb, and Y. J. SubbaRow, Amer. Chem. SOC., 1948, 70, 1096.J. H. Boothe, J. H. Mowatt, B. L. Hutchings, R. B. Angier, C. W. Waller,E. L. R. Stokstad, J. Semb, A. L. Gazzola, and Y. J. SubbaRow, ibid., p. 1099.14 S.Black, J. M. McKibbin, and C. A. Elvehjem, Proc. Soc. Exp. BWE. Med., 1941,47, 308CUTHBERTSON : HBEMOPOIETIC FACTORS. 231pig,15 monkey,ls chick,f7 dog,lS mink,ls Aedes aegypti,m Triboliumand Tenebrio moZitor.22 The typical condition in mammals is a decreasedgrowth-rate together with leucopenia and ultimately an anamia of themacrocytic type. In this review, folic acid deficiency will be used for adeficiency condition alleviated by one or other of the pteroylglutamates,and the term folic acid will be used to describe compounds promoting thegrowth of L. cccsei or 8. famlis R on folic-acid-deficient media.In man, the pteroylglutamates have been found effective in the treat-ment of a variety of macrocytic ansmias and in tropical s p r ~ e .~ ~ Folicacid will cause reticulocytosis and the return of an apparently normalblood and bone-marrow appearance in patients with pernicious anaemia,but will not prevent or relieve the symptoms of sub-acute combined de-generation of the cord found in the later stages of this disease.2P VitaminB,, will both cause complete remission of the blood symptoms and preventor alleviate the nerve changes.Compounds with Anti-folic Acid Activity.-Numerous compounds areknown to antagonize the action of folic acid in bacteria. Most of these arederived from PGA by substitution in the pteridine nucleus, the most im-portant being the 4-amino-, the N10-methyl-, and the 4-amin0-N~~-methyl-derivative.2 I n animals (rat, mouse, chick, pig, guinea-pig), administrationof these substances leads to the appearance of symptoms associated withPGA deficiency, but other toxic symptoms not reversed by PGA are pro-duced, and in the guinea-pig 2s the changes in the haemopoietic system arenot completely reversed by folic acid.The predominant effect of thesecompounds is the production of a leucopenia, followed by anaemia. Theyhave been tried clinically in human cases of leucsmia. Although 4-amino-pteroyglutamic acid appears to be the most satisfactory, i t will cause onlytemporary remissions, and difficulties are encountered because of toxicity.26* 27Apart from their use in partial control of human leucsmias, anti-folicacids have been found to inhibit the growth of the Rous sarcoma in chicks.28D. W. Woolley and H.Sprince, J . Biol. Chem., 1945,157, 447.l6 P. L. Day, W. C. Langston, and W. J. Darby, Proc. Soc. Exp. Biol. Med., 1938,l7 E. L. R. Stokstad and P. D. V. Manning, J . Bwl. Glwm., 1938, 125, 687.l8 W. A. Krehl, N. Torbet, J. de la Huerga, and C. A. Elvehjem, Arch. Biochem.,A. E. Schaeffer, C. K. Whitehair, and C. A. Elvehjem, Proc. Soc. Exp. Biol. Med.,38, 860.1946, 11, 363.1946, 62, 169.2o L. Golberg, B. de Meillon, and M. Lavoipierre, J . Exp. Biol., 1945, 21, 90.21 G. Fraenkel and M. Bfewett, Nature, 1946,158, 697.22 G. Fraenkel, M. Blewett, and M. Coles, ibid., 1948, 161, 981.23 T. D. Spies, " Experiences with folic acid," " The Year Book " Publishers Inc.,24 S . 0. Schwartz and B. E. Armstrong, J . Lab. Clin. Med., 1947,32, 1427.25 J.Innes, E. M. Innes, and C. V. Moore, ibid., 1949, 34, 883.26 S. Farber, Blood, 1949, 4, 160.27 L. 11. Rleyer, Trans. N . Y . Acad. Sci., 1948, 10, 99.28 P. A. Little, A. Sampafh, and Y. J. SubbaRow, J . Lab. Clilz. Ned., 1948, 33,1144.Chicago232 BIOCHEMISTRY.Leuchtenberger et aE. reported that pteroyltriglutamic acid inhibited thegrowbh of breast cancer in mice.29Metabolism of PGA and Conjugates.-In human cases of perniciousanaemia, sprue, and nutritional macrocytic anaemia, administration ofpteroyl-di-, -tri-, or -hepta-glutamate leads to remission of symptoms andthe di- and the tri-glutamate cause urinary elimination of folic a~id.~O> 31Conflicting results have been obtained with the use of the heptaglutamate inthe treatment of pernicious anaemia in relapse.These may be associatedwith the action of substances inhibiting the release of PGA from itsconjugates.32y 33In normal persons 30450% of administered PGA is eliminated in urinewhen given at the level of 3-10 mg. per day.34 After injection of pteroyl-di- and -tri-glutamic acid T. H. Jukes et aE.35 noted folic acid excretion inthe urine. M. E. Swenseid et aZ.36 have shown that free folic acid is excretedin the urine after administration of pteroylheptaglutamate, but this effectmay be absent if materials inhibiting the release of folic acid by deconjugasepreparations are present in the extracts used. This work could thereforebe interpreted to show that the heptaglutamates must be broken down inthe gut before absorption or utilisation.Although the evidence is veryconflicting, it appears that the heptaglutarnate is often not well utilised bypernicious-anemia patients in relapse, and it has been suggested 32y 37 thatliver extract improves the utilisation of the conjugates but the resultsobtained are probably best explained by the low doses used and the presenceof conjugase inhibitors. J. F. Wilkinson and MI. C. G. Israels 38 have shownthat pteroyltriglutamic acid and " diopterin " (a synthetic a-pteroyl-diglutamic acid not known to occur in Nature) are effective in the relief ofthe haematological effects of pernicious anaemia when given orally or byinjection. Their observations, along with those of Jukes et aE.,35 show thatthe conjugates may be broken down in the body to free folic acid.After administration of PGA (or its conjugates) only about 30% of thefolic acid may be accounted for in the urine in man : the fate of the remainderis not yet known.H.E. Sauberlich and W. I). Salmon 39 noted that administration of fofic29 R. Leuchtenberger, C. Leuchtenberger, D. Laszlo, and R. Lewisohn, Science,30 T. D. Spies, 8th. Med. J., 1946, 39, 634.31 T. D. Spies, G. Garcia Lopez, R. E. Stone, F. Milanes, R. 0. Brandenberg, andT. Aramburu, Internat. Rev. Vit. Res., 1947, 19, 1.32 F. H. Bethell, M. C. Meyers, G. A. Andrews, M. E. Swendseid, 0. D. Bird, andR. A. Brown, J. Lab. Clin. Med., 1947,32, 3.33 A. E. Sharp and E. C. Vonder Heide, Amer. J. Clin. Path., 1947, 17, 761.34 R. Steinkamp, C. F. Shukers, J.R. Totter, and P. L. Day, Proc. Soc. Ezp. Biol.Med., 1946, 63, 556.3 5 J . Lab. Clin. Med., 1947,32, 1350.S6 Ibid., p. 23.37 R. M. Suarez, A. D. Welch, R. W. Heinle, R. M. Suarez, jun., and E. M. Nelson,ibid., 1946, 31, 1294.36 Lancet, 1949, 257, 689.1945, 101, 46.3e Fed. Proc., 1949, 8, 247CUTHBERTSON : HBMOPOIETIC FACTORS. 233acid to rats led to an increased elimination of the L. citrovorurn factor inthe urine. This substance is not PGA but may be replaced in the nutritionof L. citrovorurn by PGA in the presence of t h ~ r n i d i n e . ~ ~ The importanceof this substance in mammalian metabolism is not known.H. G. Buyze and C . Engel,41,42 state that pteroylheptaglutamate istransformed by normal gastric juice into a product from which folic acidis liberated by liver homogenate but not by conjugase preparations.In the chick and the rat PGA conjugates are effective in controlling folicacid 44Thymine in large amounts can replace folic acid for the growth of 8.fcecalis R,45 and in the presence of a purine base thymine will replace folicacid in the nutrition of L.casei,46 though in the latter instance only half themaximal growth is attained. These observations lead to the hypothesisthat folic acid acts as a coenzyme in the synthesis of thymine and relatedcompounds. The relations between thymine, PGA, p-aminobenzoic acid,and the mode of synthesis of folic acid have been discussed by J. 0. Lampenand M. J. Jones.47 A possible role of histidine in the formation of folic acidhas been reported by D.A. Hall,48 who worked with 8. fcecaEis R. A relationwith tyrosine metabolism in the guinea-pig is suggested by C. W. Woodruffet aZ.,49 who showed that PGA prevented the elimination of tyrosinedcrivatives in the urine of scorbutic guinea-pigs.H. M. Kalckaret showed that 6-formylpteridine (;‘ 6-pteridylaldehyde ”) (an anti-folicacid) inhibited the activity of xanthine oxidase. “ Dopa ’’ decarboxylaseactivity was inhibited by two folic acid displacers and this inhibition wasprevented by PGA.51 The observation that the anemia produced in ratson a low-protein diet 52 is cured by the administration of folic acid suggestsa relation between folic acid and protein metabolism.Assay of Folic Acid.-It was early shown that microbiological assay offolic acid activity with L.casei and S . fcecalis often gave discordant resultswhich did not agree with each other or with the results of animal tests onrats, chickens, or monkeys.These results are now known to be due to the multiple nature of folicacid as shown in the following table.1Folic acid may be involved in certain enzyme systems.40 H. E. Sauberlich, Arch. Biochem., 1949, 24, 224.4z Nature, 1949, 163, 135.43 M. E. Swendseid, R. A. Brown, 0. D. Bird, and R. A. Heinrich, Arch. Biochem.,44 T. H. Jukes and E. L. R. Stokstad, J . Biol. Chem., 1947, 1S8, 563.45 E. E. Snell and H. K. Mitchell, Proc. Nut. Acad. Sci. Wash., 1941, 27, 1.46 E. L. R. Stokstad, J . Biol. Chem., 1941, 139, 475.47 Ibid., 1947,170, 133,4e J .Biol. Chem., 1949, 178, 861.6o Ibid., 1948,174, 771.s1 G. J. Martin and J. M. Beiler, Arch. Biochem., 1947, 15, 201.62 0. Shehata and B. C. Johnson, Proc. Xoc. Exp. Biol. Med. N.Y., 1948,%7, 332..Biochim. Biophys. Actu, 1948, 2, 217.1948, 16, 367.48 Biochem. J., 1946,40, lv234 BIOCHEMISTRY.Biological activity of PCA and related substam.Substance.Relative activity. Activity inS. fatcalis R. L. cmei. chick. rat. - - Pteroic acid .................................... 60 0.01Pteroylglutamic acid 100 100 + +Pteroyltriglutamic acid 7.5 80 4- +Pteroylheptaglutamic acid 0.3 0.2 + +........................ .......................................Crude vitamin B, conjugase from hog kidney or chicken pancreas wasshown by 0. D. Bird et to convert the heptaglutamate into a micro-biologically active form.A. Kazenko and M. Laskowski45 showed thatthe y-peptides were attacked with loss of the terminal glutamic acid, thetriglutamate thus yielding the diglutamate. Whether the conjugases candegrade the heptaglutamate to a substance with full microbiological activityis not yet known.The problem of microbiological assay of the total folic acid content ofnatural materials is further complicated by the occurrence of conjugaseinhibitors in natural sources. Glutamic protein,55 thymus nucleicand glutamates 67 have all been shown to inhibit the action of theseenzymes. There is also the possibility that the conjugases are incapable ofliberation of folic acid from all the complexes in which it may O C C U ~ .~ ~Anti-pernicious Ansmia Factor-Vitamin B,,.-Twenty-two yearsafter G. R. Minot and W. P. Murphy 58 noted the efficacy of liver in thetreatment of pernicious anzemia, the active principle was isolated in theform of dark red crystals by two independent groups of workers, E. L.Rickes et ~ 1 . ~ ~ in America and E. Lester Smith and L. F. J. Parker inEngland. The English workers used clinical tests as a guide to isolationprocedures from liver ; their last stages of purification depended on adsorp-tion 62This anti-pernicious anzemia factor has been called vitamin B,, andthis name is now in general use. Though the vitamin was originally isolatedfrom liver, it has now been produced by fermentation, using XtreptomycesAnother red crystalline substance with anti-pernicious anaemia activityand having closely related properties has been produced in fermentation8griseus.6353 J .Biol. Chem., 1945, 157, 413.5 5 A. Z. Hodson, Arch. Biochem., 1948, 16,309; J. A. Bain and H. F. Deutsch, ibid.,54 Ibid., 1948, 173, 217.p. 221.V. Mims, M. E. Swendseid, and 0. D. Bird, J . Biol. Chem., 1947,170,367.5 7 E. L. R. Stokstad, J. Pierce, T. H. Jukes, and A. L. Franklin, Fed. Proc., 1948,58 J . Amer. Med. ABBOC., 1926, 87, 470.5s Science, 1948, 107, 396.60 Biochem. J., 1948, 43, viii.7, 193.E. Lester Smith, Proc. Int. Congr. Biochem., Cambridge, 1949.E. Lester Smith, Brit. Med. J., 1949, 11, 1367.63 E. L. Rickes, N. G. Brink, F. R. Koniuszy, T. R. Wood, and K. Folkers, Science,1948, 108, 634CUTHBERTSON HBMOPOIETIC FACTORS.235with Streptomyces aureofuciens. * This substance has been called vitaminB,, (Blm has been used to describe a hydrogenation product of Bx2).Vitamin B,, isolated in the form of dark red crystals has been shown tocontain cobalt, phosphorus, carbon, nitrogen, oxygen, and hydrogen 65, 66and to -have a molecular weight of about 1500, the molecule containing oneatom each of cobalt and phosphor~s.~~, 68Vitamin B,, is most stable at pH 5 and is inactivated by acid or alkali,even in the cold.68, e6The cobalt is held in very firm combination.6* Prolonged acid hydrolysisappears to liberate phosphoric acid, ammonia, 5 : 6-dimethylbenziminazole,two 1 -substituted 5 : 6-dimethylbenziminazoles, and 2-aminopropanol, themajor fragment being an acidic red cobalt complex which has not beencharacterised.'o On fusion with alkali, pyrrole derivatives are liberated.67Infra-red spectroscopy has shown that the molecule contains bonded O-Hor N-H groups and that there are aromatic or heterocyclic nuclei andprobably few aliphatic groups.71B,, in Animal Nutrition.-The use of more refined nutritional techniqueshas shown that a number of animals require growth factors other than folicacid and the known vitamins.Three main methods have been employedto demonstrate these requirements : (1) Use of diets based on crude vegetablematerials or on casein exhaustively extracted with alcohol. (2) Use ofyoung animals derived from parents maintained on vegetable rations.(3) Use of animals treated with thyroxine to increase their apparent vitaminrequirements.J. C.Hammond and 11. W. Titus 72 and M. Rubin and H. R. Bird 73reported that the addition of fish meal or cow manure to the diet greatlyimproved the growth of chicks on an all-vegetable ration. The factor(s)responsible for the growth effects is associated with animal protein and hasbeen known by the term " Animal Protein Factor."The cow-manure factor was concentrated 74 and shown to promote the8 4 5. V. Pierce, A. C. Page, jun., E. L. R. Stokstad, and T. H. Jukes, J . Amer. Chem.65 E. Lester Smith, Nature, 1948, 162, 144.66 E. L. Rickes, N. G. Brink, F. R. Koniuszy, T. R. Wood, and K. Folkers, Science,1948,108, 134.6 7 N. G. Brink, D. E. Wolf, E.Kaczka, E. L. Rickes, F. R. Koniuszy, T. R. Wood,and K. Folkers, J . Amer. Chem. SOC., 1949, '71, 1854.6 8 K. H. Fantes, J. E. Page, L. F. J. Parker, and E. L. Smith, appendix byD. Hodgkin, M. W. Porter, and R. C. Stiller, Proc. Roy. SOC., B, 1949, 136, 592.'O B. Ellis, V. Petrow, and 0. F, Snook, J . Pharm., Pharmacol., 1949,1, 735; E. R.Holliday and V. Petrow, ibid., p. 734 ; B. Ellis, V. Petrow, and G. F. Snook, ibid., p. 60 ;J . Pharm., Pharmacol., 1949, 1, 287, 950, 957; N. G. Brink, D. E. Wolf, E. Kaczka,E. L. Rickes, F. R. Koniuszy, T. R. Wood, and K. Folkers, J . Amer. Chem. SOC., 1949,'41, 1854; E. Lester Smith, J . Pharm., Pharmacol., 1949, 1, 500.Soc., 1949, '71, 2952.71 R. Barer, A. R. H. Cole, and H. W. Thompson, Nature, 1949, 183, 198,72 Poultry Sci., 1944, 23, 49, 471.7s J .Biol. Chem., 1946, 163, 387.HI. R. Bird, M. Rubin, and A. C . Groschke, ibid., 1948,174,611236 BIOCHEMISTRY.growth of the chick and the hatchability of eggs and to be stored for 10-15weeks in the hen.75 Sardine meal 7, produces effects very similar to thoseobtained with cow manure, and the properties of the cow-manure factorand animal-protein factor of fish solubles are very similar. 76Vitamin B,, has been shown to promote chick growth under con-ditions similar to those used in investiga.tion of the animal-proteinfactor.77R. J. Lillie, C. A. Denton, and H. R. Bird78 have shown that the effectsassociated with the cow-manure factor may be obtained by the administrationof Vitamin B,, orally or by injection.The identity of the animal-protein factor and vitamin B,, is renderedprobable because, in a fermentation product, microbiological activitytowards Lb.Zeichmannii 313 and chick-growth activity both increasedduring purification, and a highly concentrated extract controlled perniciousanaemia.79 This material was shown to have B,, activity, the active fractionbehaving on paper chromatograms in the same way as that from liverextracts. 8oA nutritional deficiency in rats on a vegetable protein diet has beendescribed by L. M. Zucker and T. F. Zucker.81 The condition is preventedby animal protein, and this growth factor has been called zoopherin. C. A.Cary et u Z . ~ ~ have described a deficiency in rats fed on extracted caseinand ascribe this to absence of “nutritional factor X.” The deficiencyproduced and the properties of the factors make it appear that zoopherinand factor X are identical.Here again the deficiency may be overcomeby use of vitamin BI2. Further support to the view that B,, factor Xand the animal-protein factor are the same substance, or closely relatedsubstances, is given by the observation that the amounts required rise withincreasing protein 82bB. H. Ershoff 84 has shown that the administration of thyroxine increasesvitamin requirements : in thyroid-treated rats normal growth and survivalmay be obtained by administering whole liver. Workers using vegetablediets with added thyroid or iodinated casein have demonstrated B,,75 M. Rubin, A. C. Groschke, and H.R. Bird, Proc. Soc. Exp. BWZ. Med., 1947,66, 36.76 A. R. Robblee, C. A. Nichol, W. W. Cravens, C. A. Elvehjem, and J. C. Halpin,J . Biol. Chem., 1948, 173, 117.7 7 W. H. Ott, E. L. Rickes, and T. R. Wood, ibid., 1948,174, 1047.78 Ibid., 1948, 176, 1477.7* E. L. R. Stokstad, A. Page, J. Pierce, A. L. Franklin, T, H. Jukes, R. W. Heinle,80 W. F. J. Cuthbertson and E. Lester Smith, Biochem. J., 1949, 44, v.81 L. M. Zucker and T. F. Zucker, Arch. Biochem., 1948, 16, 115; Proc. SOC. Exp.B2 Fed. Proc., 1946, 5, (a) 128, (b) 137.e3 A. M. Hartman, L. P. Dryden, and C. A. Caw, A&. Biochem., 1949, 23, 165;H. R. Bird, M. Rubin, and A. C. Groschke, Off. Rep. of 8th World Poultry Congr., 1948,No. 23, p. 187.M. Epstein, and A. D. Walsh, J.Lab. CZim Ned,, 1948.33, 860.Biol. Med., 1948, 68, 432.Arch. Biochem., 1947, 15, 365CUTHBERTSON : HBMOPOIETIC FACTORS. 237deficiency in the rat,S5 in the chick,86 and in the mouse,87 and B,, assaymethods have been developed from these findings. P. H. Erschoff 88failed to demonstrate B,, deficiency in thyroid-treated rats. In theReporter’s laboratory, rats on vegetable diets given L-thyroxine developeda deficiency, which was not completely relieved by B,, but prevented byadministration of B,, and B13, prepared by the method of A. F. Novakand S. M. H a ~ g e . ~ ~ Using rats and chicks on diets closely similar to thoseused in B,, investigations, Novak and Hauge obtained a. deficiency attributedto the absence of B13; this has not yet been isolated in the pure state butfrom its chemical properties is clearly different from B12.Stokstad et a1.W have shown that vegetable diets may lead to deficienciesnot corrected by B,, or other known factors.Vitamin B,, is probablyessential in the nutrition of the dog 91 and the ~ i g . ~ l aReviewing the evidence as a whole it can be stated that vitamin B,,can replace factor X, zoopherin, and the cow-manure factor, which areprobably identical with, or closely related to, B,,, but this has not yet beenconfirmed by isolation of these factors in the pure state. Animal-proteinfactor activity can usually be completely replaced by B,,, but here againidentity has not been established. In some instances animal-protein factoractivity may be due, not to B,,, but to B13, to the substance responsiblefor Erschoff’s results, or to some other unknown factor(s).Microbiological Assay of Vitamin BI2,--A hitherto undescribed growth-factor for LactobaciEZus lactis Dorner ATCC 8000 was shown by IM.s. Shorb 92to be present in liver extracts. In 1948, crystalline B,, was shown to havevery high activity in the promotion of growth of Lb. Z ~ c t i s . ~ ~ A number ofother organisms has been shown to require B,, under certain conditions,and assay methods have been published involving the use of Lb. lactisATCC 8000 and ATCC 1097,9* Lb. Zuctis 1175,95 Lb. Zeichmnnii 313 ATCC86 U. D. Register, W. R. Ruegamer, and C. A. Elvehjem, J . Biol. Chem., 1949,177,129.8 6 C. A. Nichol, L. S. Dietrich, W. W. Cravens, and C.A. Elvehjem, Proc. SOC. Exp.BioE. Ned., 1949, 70, 40; A. R. Robblee, C. A. Nichol, W. W. Cravens, C. A. Elvehjem,and J. G. Halpin, ibid., 1948, 67, 400.87 D. K. Bosshardt, W. J. Paul, K. O’Doherty, J. W. Huff, and R. H. Barnes,J . Nutrit., 1949, 37, 21.88 J . Exp. Med., Surgery, 1948, 6, 438.O0 Ibid., 1949, 180, 647.O1 W. R. Ruegamer, W. L. Brickson, N. J. Torbet, and C. A. Elvehjern, J . Nutrit.1948, 36, 425.R. W. Heinle, A. D. WeIch, and J. A. Pritchard, J . Lab. Clin. Med., 1948, 33,1647; A. L. Neumann, M. F. James, J. L. Krider, and B. C. Johnson, Fed. Proc.,1949, 8, 391; A. L. Neumann, J. L. Krider, and B. C. Johnson, Proc. SOC. Exp.Biol. Ned., 1948, 69, 513; A. G. Hogan and G. C. Anderson, Fed. Proc., 1949, 8, 385;R. Braude, Brit.J . Nutrit., 1949, in the press.O2 J . BioE. Chem., 1947,169,455.O8 M. S. Shorb, Science, 1948,107, 397.94 M. C. Caswell, L. K. Koditschek, and D. Hendlin, J . Biol. Chem., 1949,180, 125.O5 Von K. Kocher and 0. Schindler, Internat. Review Vit. Res., 1949,20,369.J . Biol. Chem., 1948,174, 647238 (BIOUHEMISTRY.7830,96 EugZem gracilis var. bacillu~is,~~ Lb. luctis ATCC 8000,98 and Lb.Zeichmannii ATCC 4797.99A cup-pla te method loo developed from penicillin-assay technique over-comes many of the difficulties encountered in the tube method, though itis not as sensitive (lower limits about 0.05 vg./mf. compared with 0.001pg./ml. with tube methods) and is more subject to interference.Great difficulty has been experienced with B,, assays by normal micro-biological procedures, owing to the effects of oxygen and reducing agentson the growth of Lb.Zuctis and Lb. leichrn~nnii.~5~ lo1 Further difficultieswere encountered in the development of assay methods with Lb. luctisATCC 8000 in that this strain, unlike the variant used by Sh0rb,~3 requiresan oleic acid source '' Tween 80." g9, 100, l01a* lo2Thymidine lo3 and other deoxyribosides have been shown to replace B,,for the growth of Lb. Eactis and Lb. leichmannii.lo3* lU43 lo5The activity of the deoxyribosides is of the order of 1/1000-1/5000ththat of B1,, but interference from these compounds is readily detected inthe plate test lo6 and may be inhibited by high salt concentrations,lW or paperchromatography may be used to remove these corn pound^.^^^In tube assays, alkali treatment which destroys B,, may be employedto differentiate between B,, and deoxyriboside activity.lo7Paper psrtition-chromatographic methods have been used to identifyand investigate the number of factors responsible for the B,, activity ofliver extracts.About 0.003-043 vg. of total activity is applied to thepaper which is then developed (usually with n-butanol). The developedstrip is then applied to the surface of a B,,-deficient agar medium seededwith Lb. Eactis 80* lo5 or Lb. leichmannii.lOs On development overnight, zonesof growth appear at sites corresponding to the B,,-active fractions. WithLb. lactis the clinically active factors B,, and B,, give dense growth-zones,but the deoxyribosides produce areas of faint growth.In our hands, the96 C. E. Hoffrnann, E. L. R. Stokstad, A. L. Franklin, and T. H. Jukes, J . Biol.Chem., 1948,176, 1465.97 S. H. Hutner, L. Provasoli, E. L. R. Stokstad, C. E. Hoffmann, M. Belt, A. L.Franklin, and T. H. Jukes, Proc. SOC. Exp. Biol. Med., 1949, 70, 118.98 G. E. Shaw, Nature, 1949, 164, 187.99 H. R. Skeggs, J. W. Huff, L. D. Wright, and D. K. Bosshardt, J . Biol. Chem.,1948,176, 1459.100 W. F. J. Cuthbertson, Biochem. J., 1949, 44, v ; J. C. Foster, J. A. Lally, andH. B. Woodruff, Science, 1949, 110, 507.101 (a) W. Shive, J. M. Ravel, and R. E. Eakin, J . Amer. Chem. Soc., 1948, 70, 2614;( b ) R. D. Greene, A. J. Brook, and R. B. McCorrnack, J . Bid. Chem., 1949, 178, 999;(c) L. K. Koditschek, D.Hendlin, and H. B. Woodruff, ibid., 1949, 179, 1093.102 L. D. Wright, H. R. Skeggs, and J. W. Huff, ibid., 1948, 175, 475.103 E. E. Snell, E. Kitay, and W. S. McNutt, ibid., p. 473.104 V. Kocher, Internat. Review Vit. Res., 1949, 20, 441.105 E. Lester Smith and W. F. J. Cuthbertson, Biochem. J., 1949, 45, xii.106 W. F. J. Cuthbertson, Internat. Congr. Biochem., Cambridge, 3949.107 C. E. Hoffmann, E. L. R. Stokstad, B. L. Hutchings, A. C. Dornbush, and T. H.108 W. A. Winsten and E. Eigen, ibid., 1949,177, 989.Jukee, J . BioZ. Chem., 1949,181,635CUTHBERTSON : HBMOPOIETIC FACTORS. 239zones produced on Lb. Zeichmannii plates with B,, and the deoxyribosidesare closely similar. Various factors have been found in liver extracts andtentatively identified in this way.lo4Microbiological assay methods may be applied to refined liver extractsand fermentation concentrates with success, but little is known of theapplication of the techniques to crude materials, e.g., foodstuffs, and suitableextraction procedures have not yet been described.Role of B,, in Intemediaxy Metabolism.-Vitamin B,, is thought toplay a part in vital metabolic processes. Work on bacteria has shown thatit may be particularly involved in the biochemistry of the deoxyribosidesthat are of great importance in nucleic acid metabolism. More recent workwith vertebrates indicates that B,, may play some role in the metabolismof the methyl group.Thymidine and the other deoxyribosides have been shown to replaceB,, (at least in part) in the nutrition of Lb.Zactis,101c*104,105 and Lb.leichmannii.99~ 109Folic acid, thymine or the other pyrimidines or purines, or deoxyribosewill not replace B,, in the nutrition of these bacteria; consequently.it issupposed that B,, plays a role in an enzyme system that brings about thecombination between the purine or pyrimidine and deoxyribose.lo2M. Friedkin et al.l10 have shown that deoxyribose phosphate under theinfluence of liver nucleoside phosphorylase may combine with hypoxanthineto form hypoxanthine deoxyriboside.The observation that the other deoxyribosides may be used equally aswell as thymidine while deoxyribose itself is ineffective for growth mayperhaps be explicable on the assumptions that combined deoxyribose is theessential requirement and that the deoxyribose in this state may be freelytransferred from one purine or pyrimidine base to another by an enzymesystem in these bacteria.The discovery by Friedkin et al. that deoxyribosephosphate may react with hypoxanthine to form the deoxyriboside opensthe attractive speculation that B,, is essential for an enzyme system whichphosphorylates deoxyribose, the sugar phosphate then reacting with thepurine and pyrimidine bases to form the deoxyribosides.Vitamin B,, has been shown by I. 2. Roberts et ~ 1 . 1 ~ ~ to increase the rateof synthesis of deoxyribonucleic acid in Lb. Zeichmnnii and increase therate of phage (T4J formation in E . coli ; 112 this again emphasises the possiblerole of the vitamin in nucleic acid metabolism.Vitamin B,, is required by Lb.Zuctis under aerobic conditions but maybe dispensed with under anaerobic condition^.^^^ loo$ lola It may therefore beconcerned with biological oxidation reactions. Prom the evidence availableit appears to be essential for the combination of deoxyribose with purineor pyrimidine bases under aerobic conditions.Vitamin B,, may have some part to play in the metabolism of methionine,los E. Kitay, W. S. McNutt, and E. E. Snell, J . Biol. Chem., 1949, 177, 993.110 Ibid., 1949,178,527.lf2 R. B. Roberts and M. Sands, ibid., p. 710.ll1 J . Bact., 1949, 58, 709240 BIOCHEMISTRY.for in E . coZi it may be replaced by methionine.l13 A study of B,, deficiencyin the rat and the chick has also indicated a relation between B,,, methionine,and choline.From the literature it is not possible to decide whether theseeffects are best interpreted as showing that B,, enters into methyl-groupmetabolism directly in the animal body or indirectly via the intestinal floraof the gut.A. E. Schaefer et aZ.l14 showed that, in the rat and chick, B,, in thediet markedly reduced symptoms of choline deficiency. M. B. Gillis andL. C . Norris 115 showed that a liver paste rich in B,, and of low choline contentwas more effective than choline itself in preventing deficiency symptomsin chicks on low-methyl diets. C. A. Hall and W. A. Drill 116 showed thatliver extracts prevented hepatic fibrosis and fatty livers normally encounteredin rats on the Himsworth-Glynn diet.A.E. Schaefer et ~ 1 . ~ 1 ~ claim that, in chicks, choline spares B,, and thatB,, lowers the need for choline. It is of interest to note that the chickdiets used by Stockstad et aLgO for B1,-deficiency studies are supplemented withmethionine and choline. At the moment the conclusion may be drawn thatthe addition of B,, to the diet reduces the methyl requirement in the ratand chick.Treatment of Pernicious Ansmh-Crystalline B,, has been shown bya number of workers 11* to control the haematological condition in perniciousanaemia. Unlike folic acid, B,, also controls the neurological lesi0ns.1~~C. C. Ungley 12* has given a very full account of the amounts of B,, requiredin the control of pernicious anaemia. In most instances 10 pg. per fortnightby injection suffice, but doses of 20 pg.per week are recommended for generaluse although initial treatment and control of nervous lesions may need muchlarger amounts.Vitamins B12b (probsbly identical with Smith's second red factor) andB,, are also effective in the treatment of pernicious anzemia. From thesmall amount of work published on BlZn, i t seems to be rather less activethan B,,.Vitamin B,, has been shown to be effective in the control of nutritionalmacrocytic anaemia and sprue,121+ but ineffective in some cases of macrocyticanzemia of pregnancy and infancy.113 W. Shive, Amer. Acad. Sci., 1950, in the press.11* Ped. PTOC., 1949, 8, 395.11' Ibid., 1949,71, 202.11s R. MTest, Science, 1948, 107, 398; C. C. Ungley, Lancet, 1948, I, 771; Brit.Med.J., 1948, 11, 154; T. D. Spies, R. M. Suarez, G. Garcia Lopez, G. Fernando Milanes,R. E. Stone, Lopez R. Toea, T. Aramburu, and S. Kartus, J . Amer. Ned. ASSOC., 1949,139, 521 ; IF. H. Bethell, M. C. Meyers, and R. B. Neligh, J . Lab. Clin. Med., 1948, 33,1477.J . Biol. Chem., 1949, 178, 487.PTOC. SOC. Exp. Biol. Med., 1949, 69, 3.11s M. Finland and W. B. Castle, New Erzgland J . Med., 1948, 239, 328.120 Brit. Med. J., 1949, 11, 1370.121 T. D. Spies, R. E. Stone, G. Garcia Lopez, G. Fernando Milanes, Toca R. Lopez,182 J. C. Patel, Brit. Med. J., 1948,II, 934.and T. Aramburu, Lancet, 1948, 255,519CUTHBERTSON : HLEMOPOIETI(3 FACTORS. 241Relation between Folic Acid and Vitamin B,, in Pernicious Anaemia.--Inanimal nutrition, both vitamins have independent effects, i.e., all resultsin animal feeding may be explained by the independent action of these twosubstances ; thus the administration of folic acid to B,,-deficient animalshas no effect, and conversely B,, will not relieve folic acid deficiency.123 I nhuman nutritional macrocytic anamias, evidence is now accumulatingthat these diseases may be due to dietary insufficiency (or failure of absorp-tion) of one or both of these factors.Cases have been reported that respondto only one or the other type of vitamin. In bacterial nutrition the samething is met, folic acid will not replace B,,, nor will B,, replace folic acidfor growth of the lactobacilli under conditions studied hitherto. Investig-ations with bacteria have so far shown that these vitamins are concernedwith different stages of pyrimidine and purine metabolism.Folic acidenters into the reactions essential for the synthesis of thymine, but B,, isrequired (under aerobic conditions at least) for the formation of the nucleo-sides, i.e., for the formation of the purine and pyrimidine deoxyribosides.In human Addisonian pernicious anaemia the position is rather different.In these patients there is not only the macrocytic anaemia and megaloblasticbone marrow typical of the nutritional macrocytic anamias, but there isalso an alteration in the stomach which fails to secrete acid and changesin appearance. The disease is not nutritional in origin, but appears to bedue to an error in metabolism which leads to a condition very like thenutritional macrocytic anamias.Patients with Addisonian perniciousanamia often show other symptoms, such as glossitis, and sooner or laterif the anamia is not adequately controlled the condition of sub-acutecombined degeneration of the spinal cord with attendant nervous symptomsmay arise.Either folic acid (by mouth or by injection) or B,, (by injection) willcontrol the hamatological condition. If folic acid alone is used then thecondition of subacute combined degeneration of the cord will appear intime, and this condition is not improved even with large doses of folicacid.12* I n the control of the hamatological signs, pteroylglutamic acid isrequired in doses of 2-10 mg. per day, but B1, is effective a t the rate of1-2 pg.per day. F. H. Bethell et ~ 1 . ~ ~ suggested that liver extracts actedby liberating free folic acid from the bound forms existing in natural foods.In experiments to test this hypothesis the findings were conflicting. Theresults have been reviewed and reported by Wilkinson and I ~ r a e l s , ~ ~ whohold that the hypothesis can no longer be maintained, but L. S. P. Davidson 125thinks that the supposition is correct. Even in serious cases of perniciousanamia, the response to B,, treatment is usually rapid. Not much is knownof the amount of unavailable (bound) folic acid in the patient’s diets, butit is unlikely that these diets contain sufficient to account for the rapidresponses to BI2. If, therefore, this hypothesis is t o be tenable, the boundlZs E.Koditmhek and K. J. Carpenter, Biochem. J., 1948, 43, i.lap M. C. G. Israels and J. F. Wilkinson, B&. Med. J., 1949,11, 1072.la6 Lancet, 1949, 257, 814242 BIOCHEMISTRY.folk acid must be stored in the patient's body and utilised only when B,,is administered-this bound folic acid may not be a conjugate but mightbe the compound investigated by Buyze and Engel *l* *3 which is formed onincubation of folic acid with gastric juice.B$,-deficiency in the rat and the chick leads to a decreased growth rate,but anaemia is not a predominant symptom, although in folic acid deficiencyleucopenia and anaemia are readily obtained. An anmmia in dogs has beendescribed as not responding to folic acid but responding to liver extract,and in chicks 126 the administration of B,, together with folic acid increasedthe rate of haemoglobin regeneration after the induction of a severe anaemiawith phenylhydrazine.Observations on folic acid antagonists may be used to throw light on therelation between folic acid and B12.L. M. Meyer et aZ.12' treated pernicious-ansmia patients with a folic acid antagonist (" Met-Fol-B," methylpteroicacid) which they found prevented the action of vitamin B,, in promoting therelief of hzematological symptoms. These experiments tend to show thatvitamin B,, does act, at least in part, through the mediation of folic acidwhich is essential for its activity. Unfortunately, in these experiments i tis not certain that the " Met-Fol-B " and " Amethopterin " acted only byantagonising folic acid, for these workers did not show that the action ofthese substances could be overcome by the administration of pteroyl-glutamic acid.This criticism is offered because J. Innes et have shownthat, although aminopterin will produce, in the guinea-pig, a hamatologicalcondition resembling that expected in folic acid deficiency, the effects arenot reversed by folic acid. The anti-folic acids are highly toxic and i t maywell be that they act on the hzemopoietic system not only by blocking theeffects of folic acid but also in other ways. Thymidine in large doses hasbeen shown to cause a haematological response in pernicious anaemia.128 Inbacteria this compound may replace B,, or enable organisms to grow whenfolic acid metabolism is blocked.lo1C* lo** lo5~ lo% 129 The mode of action in thepernicious-anamia patient is not known.An assay method for vitamin B,, under consideration by a U.S.P.Committee depends on the observation that in the presence of sulphanilamide(which prevents the metabolism of p-aminobenzoic acid) B,, is apparentlyrequired for growth of E .coli (private communication). These observationsagain indicate a relation between B,, and folic acid metabolism.Sufficient facts are not available to interpret the finding that either folicacid or B,, will control the hzematological condition in pernicious anzemia ;at the moment the speculation which seems most worthy of investigation isthat B,, is needed to make available folic acid from some bound form (orprecursor) present in the diet or stored in the body.12* C.A. Nichol. A. E. Harper, L. S. Dietrich and C. A. Elvehjem, Fed. Proc., 1949,l27 Amer. J . Med. SGi., 1949, 818, 197.12* W. Shive, R. E. Eakin, W. M. Harding, J. M. Ravel, and J. E. Sutherland,8, 233.lSa K. Hausmann, Lancet, 1949,157,962.J . Amer. Chem. Soc., 1948, 70, 2299CUTHBERTSON : HBMOPOIETIC FACTORS. 243Egtrinsic and Intrinsic Faetor.-The classical experiments of Castle(reviewed by Ungley 13*) showed that for oral treatment of pernicious anmmiacertain food materials, though ineffective by themselves, did producehmmatological responses if they were digested with normal human gastricjuice before administration. On the basis of this work, Castle postulatedthat in these foods (beef muscle) there was present a dietary extrinsic factorand that in normal gastric juice there was an intrinsic factor.On incubationthese substances were thought to interact to produce the material thatbrought about the hmnatological response. The fact that refined liverextracts have only slight activity when given orally, although they may bevery active when injected, has been recognised for a long while and it hasbeen shown 131 that the oral activity of such extracts may be much increasedby incubation with normal gastric juice. In spite of these observations,the activity of liver extracts has been thought to be due in the main to theinteraction product of Castle’s extrinsic and intrinsic factors. RecentlyL. Berk et ~ 1 .~ 3 , have shown that 5 pg. of B,,, given orally, per day had noeffect on pernicious-anemia patients, but that if this amount were ad-ministered with neutralised human gastric juice a hematological responsewas obtained. These observations show that B,, can act as the extrinsicfactor. Although satisfactory B,, assays are not available for beef muscle(the most commonly used source of extrinsic ‘factor), the B,, content isprobably about 0.05 pg./g. (rat tests 133 and unpublished preliminary testswith Lb. Zuctis in the Reporter’s laboratory). This concentration of B,, issufficient to explain the effects of beef muscle without postulation of afurther type of B,,.J. L. Ternberg and R. E, Eakin134 state that gastric juice contains aheat-labile substance that combines with B,, to form a microbiologicallyinactive complex from which the B,, may be released by heating.Thisheat-labile substance, which they term “ apoerythein,” may be obtained inrelatively large amounts from normal gastric juice and hog gastric mucosa(both of which are good sources of Castle’s intrinsic factor), but only smallamounts are present in the gastric juice from pernicious-anemia patients.It is too early to identify this substance with Castle’s intrinsic factor, butthe possibility would appear to be worth investigation.Berck et ~ 1 . l ~ ~ and F. H. Bethel1 et aZ.118 have shown that pernicious-anemia patients in relapse eliminate large amounts of B,, in the feces.From the foregoing evidence i t is probable that normal gastric juice(the intrinsic factor) potentiates the absorption of B,, or prevents its lossin the alimentary tract.At present no firm conclusions may be drawn about the relation between130 C.C. Ungley, Nature, 1936, 137, 210.131 F. Reimann and F. Fritsch, 2. klin. Med., 1934, 126, 469.New England Med. J., 1948,239, 911.188 U. J. Lewis, U. D. Register, H. T. Thompson, and C. A. Elvehjem, Proc. SOC.134 J . Amer. Chem. SOC., 1949,71, 3868.Exp. Biol. Ned., 1949, 72, 479244 BIOCHEMISTRY.folic acid and vitamin B,, in metabolism or about the fundamental bio-chemical defects in pernicious anaemia. Much of the evidence is conflictingand further facts are urgently required, although the main problems maybe very near to solution. Pernicious anaemia may, however, now be definedas caused by B,, deficiency which is brought about by a failure in absorptionowing to lack of the intrinsic factor.W. F. J. C.8. CARO!L’ENOIDS, VITAMIN A, AND VISUAL PIGmNTS.Carotenoids.-A new book gives a comprehensive account of thechemistry of the carotenoids and provides a firm foundation for morebiochemical studies. The work of Karrer’s school on the 5 : 6-epoxidesof carotenoids, which undergo isomerization to furanoid structures is fullydescribed, and among the other interesting results are the findings thatviolaxanthin is the diepoxide of zeaxanthin, and flavoxanthin the furanoidisomer of lutein epoxide.The biogenesis of carotenoids is a difficult problem. In the chromato-graphy of many plant extracts a colourless zone, adsorbed below the colouredbands, is indicated by its fluorescence when exposed to ultra-violet rays ina dark room.2p3 The effect is usually due to phytofluene * (C,oHs4), acolourless carotenoid containing 7 double bonds (of which 5 are conjugated)and showing sharp maxima at 332, 348, and 367 mp.in h e ~ a n e . ~ , ~ Arelated compound, phyt~fluenol,~ has been obtained from tomatoes.Phytofluene also occurs in the yeast Rhodotorula rubra, the pigment fractionof which contains torulene (purple red; 13 conjugated double bonds),y-carotene, 8-carotene, two yellow pigments (principal maxima at 440 and400 mp.), and phytofluene. Ultra-violet irradiation of the yeast producesmutants (orange, yellow, or white) : the white mutant produces no phyto-fluene.8 It is suggested9 that the stages in pigment biosynthesis in thered yeast are as follows :Block in Block inalbino mutant orange mutantUnknown -:+ phytofiuene _3 yellow and orange -!+ red pigments.precursors pigmentsGenetical blocking is a very promising approach to biogenesis in yeastsKarrer and Jucker, “ Carotenoide,” 1948, Verlag Birkhausen, Basel.H.H. Strain, Nature, 1936, 137, 946.L. Zechmeister and A. Polgar, Science, 1944, 100, 317.L. Zechmeister and A. Sandoval, Arch. Biochem., 1945, 8, 425.0 L. Zechmeister and A. Sandoval, J . Amer. Chem. SOC., 1946, 68, 197.7 L. Zechmeister and J. H. Pinckard, Experientia, 1948, 4, 474.* H. H. Strain, “ Leaf Xanthophylls,” 1938, Carnegie Inst.J. Bonner, A. Sandoval, V.W. Tang, and L. Zechmeister, Arch. Riochem., 1946.L. Zechmeister, American Scientist, 1948, 56, 605.10, 113MORTON : CAROTENOIDS, VITAMXN A, AND VISUAL PIGMENTS. 245although it does not necessarily follow that the stages will be the same inleaves. In plant organs which produce considerable quantities of carote-noids in the absence of chlorophyll, a substance showing a deep-bluefluorescence and one broad absorption band with Amax. 343-349 mp. (inhexane) is found. Another compound with hma,. 284 mp. does not fluoresce.Galloxanthin,lo a carotenoid from chicken retinas, shows maxima at 380,401, and 422 mp. (antimony trichloride colour test, Amax. ca. 790 mp.), andmust fall between phytofluene and @-carotene in respect of conjugateddouble bonds.Provitamins A.-The symmetrical molecule of all-trans-(3-carotene remainsthe most important as well as the most potent provitamin A foiind.inNature. An intact half of the (3-carotene molecule is found in a considerablenumber of carotenoids each of which yields vitamin A in vivo. Certainepoxides act as provitamins presumably because the oxygen can he: removedin vivo.The work begun by Gillam 11 and greatly extended by Zechmeister andhis colleagues displays the importance of cis-tvuns-isomerism in the caro-tenoids. Of the 11 double bonds in @-carotene, 2 are fixed in the ringsystems and, according to Pauling, 4 others are spatially hindered fromrearrangement (but see L. Pauling ll~). The remaining 5 double bondspermit the existence of 20 isomers, 13 of which have been observedThe chromatographically. Several of them have been prepared pure.12, l3all-truns-form of a carotenoid is the deepest in colour; all the isomersshow spectra more or less displaced in the direction of shorter wave-lengths.The relationship between stereochemical configuration and provitamin Aactivity has been carefully studied.The isomers of all-trans- p-caroteneare labelled neo-@-carotene A, B . . . if adsorbed less strongly and neo-(3-carotene T, U . . . if adsorbed more strongly, A and T being nearest to theall-trans-form on a column. On a scale in which the provitamin A activityof all-trans-@-carotene is 100, the activities by the growth test of othercarotenoids are as follows : =-carotene, all-trans- 53,14 neo-U (9 mono-cis ? ) 13,14 neo-B 16; l5 p-carotene, all-trans- 100, neo-B 53,15 neo-U (3mono-cis) 38 ; l7 y-carotene, all-trans- 43,15 pro-y-carotene (a poly-cis-10 G.Wald, J . Qen. PhysioZ., 1948, 31, 377.11 A. E. Gillam, M. S. el Ridi, and S. K. Kon, Biochem. J., 193?,31, 1605.11a L. Pauling, Helv. Chim. Acta, 1949, 32, 2241.l2 E. M. Bickoff, L. M. White, A. Bevenue, and K. T. Williams, J . Ass. 03. Agric.13 F. T. Jones and E. M. Bickoff, ibid., p. 776.l4 H. J. Deuel, jun., E. Sumner, C. Johnston, A. Polgar, and L. Zechmeister, Arch.15 L. Zechmeister, Bull. SOC. Chim. biol., 1949, 31, 961.l6 H. J. Deuel, S. M. Greenberg, E. Straub, T. Fakin, A. Chatterjee, and L. Zech-1 7 H. J. Deuel, jun., C. Johnston, E. Sumner, A. Polgar, and L.Zechmeister, ibid.,Chem., 1948, 31, 633.Biochem., 1945, 6, 157.rneister, Arch. Biochem., 1949, 23, 239.1944, 5, 107246 BXOUHEMISTRY .form) 44 21 (41),Z2 neo-P 21,15 mixture of neo-forms 10; l5 cryptoxanthin,all-trans- 57,185Judged by the amount of storage of vitamin A in the liver and kidneysF3the relative activities are : all-trans-p-carotene 100, neo-p-carotene-B 48,neo-p-carotene-U 33, all-tram-a-carotene 25. The last produced smallerstores of vitamin A than its growth-promoting power would lead one toexpect.Some of the isomerides occur in Nature; thus one analysis of the p-carotene of grass shows all-trans, 77.7y0 ; neo-U, 12.9% ; neo-B, 9.4%.Bending of a-, p-, or y-carotene and cryptoxanthin molecules reducesthe biological activity by half or two-thirds.The results make a tidypattern in spite of the fact that accurate comparisons by biological methodsare not easy in this field. Whether or not, as a result of feeding thesestereoisomers, cis-trans-isomers of vitamin A are formed, is not known.So far no direct carotenoid precursor of vitamin A, is known and itseems likely that vitamin A, is always formed by dehydrogenation of vitaminA or its precursors in vivo.Biochemical Roles of 0arotenoids.-The part played by carotenoids inthe leaf is still far from being ~nderstood.~~ In diatoms (Nitzschia dissipatu,Nitxschia spec. cf. ovalis) there is ifi fucoxanthin-chlorophyll-protein com-plex ; the living cells show selective absorption a t 500-560 mp. attributableto the fucoxanthin-protein.Light so absorbed may cause chlorophyll tofluoresce and also may participate in photosynthesis, with chlorophyll asa necessary mediator. The mode of transfer of energy in the complex isnot known.25 The phenomenon is unusual since the light absorbed bycaroterroids in green alga or the higher plants does not contribute tophotosynthesis .24aCarotenoids act as photo-receptor substances in the phototropic bendingof etiolated oat seedlings and in the phototropic responses of unicellularspore bearers of the mould Phywrnyces. There is fairly good correspondence(a) between the absorption spectra of the carotenoids concerned and thephototropic sensitivity curves and (b) between the sites of carotenoiddeposition and the photosensitive zones.26 The phototropic responses ofgreen flagellates seem to be due to light absorbed by astaxanthin.72e0-A,~~* 2o 42, neo-U 27.15I8 H.J. Deuel, j u n , E. B. Meserve, C. H. Johnston, A. Polgar, and L. Zeichmeister,1s G. S. Fraps and A. R. Kemmerer, Ind. Eng. Chem, Anal., 1941, 13, 806.20 H. J. Deuel, jun., E. B. Meserve, A. Sandoval, and L. Zechmeister, Arch. Bwchent.,21 L. Zechmeister, Abstrtccts 1st International Congress of Biochemistry, 1949, 244.z2 L. Zechmeister, J. H. Pinckard, S. M. Greenberg, E. Straub, J. Fukui, and H. J.23 R. M. Johnson and C . A. Baumann, ibid., 1947, 14, 361.24 G. Wald, Vit. and Hor., 1943, 1, 195.24a J, H. C . Smith, J . Chem. Educ., 1949, 28, 631.s5 E. C. Wassink and J. A. H. Kersten, Enzymologia, 1946, la, 3.26 G.Wald, ‘‘ Harvey Lectures Series,” 1946, 41, 117.Arch. Biochem., 1945, 7, 447.1946, 10, 491.Deuel, Arch. Biochem., 1949, 23, 242MORTON : CAROTENOIDS, VITAMIN A, AND vIsufi PIGMENTS. 247SpiriIlo~anthin,~7 the major pigment obtained from the bacteriumRhodospirilZum rubrum, is probably rhodoviobscin.as It apparently is notconcerned in phototactic responses which are attributed to residual caro-tenoids and bacteriochlorophyll.29Several carotenoids take part in reproductive cycles and a very interest-ing but difficult aspect of comparative biochemistry is being opened up.In some algae the pigment of the male gametes is mainly @-carotene whilstthe female gametes contain fucoxanthin and chl~rophyll.~~ Recent workon rainbow trout (Sulmo irideus Gibb) implies the existence of " fertilizationhormones "-androgamones AI and AII and gynogamones GI and GII.The trout eggs contain astaxanthin, @-carotene, and lutein ; astaxanthincauses the GI biological response, it activates the spermatozoa and antago-nises AI.31 Sea urchins (Arbaciu pustulosa), however, contain echinochrome 32(3 : 5 : 6 : 7 : 8-pentahydroxy-2-ethyl-1 : 4-naphthaquinone) as the GI sub-stance-a very surprising structural variation compared with astaxanthin.The carotenoids of the brown trout (Sulmo truttu Linn.) have been studiedthroughout the life-cycle.33 The adult trout tissues contain @-carotene,lutein, and astaxanthin ; muscle contains free hydroxy-carotenoids butlittle or no carotene, the liver contains carotene and lutein but no astaxanthin,whilst the red and the yellow chromatophores of the skin contain luteinand astaxanthin, both esterified.The ova of the spawning female containall three pigments, a large part of the total having been transferred from themuscle tissue, but the chromatophores of the adult do not suffer depletion.Lutein and astaxanthin are free in the egg yolk but esterified in the embryo ;p-carotene, although present in freshly spawned ova, is not detectable inthe embryo a t any stage, presumably because it is used to form vitamin A.Lutein and astaxanthin are transferred without loss from the yolk to thebody of the embryo rather late in the larval period and are responsible forthe development of xanthophores and erythrophores.In the larva, theyolk-sac carotenoids are concentrated in a lipoid droplet which rises to thetop when the urethane-narcotized larva is held head-downwards in a glasstube. The portion of the sac containing the pigmented droplet of fat maybe tied off and cut away. This removal of about 90% of the yolk caro-tenoids results later in larvae slightly below normal in size and with very fewchromatophores and those pale, but the larvae show no other obvious defect.The carotenoid distribution suggests that the maintenance of normal2 7 P. B. van Niel and J. H. C. Smith, Arch. mikrobiol., 1935, 6, 219.28 A. Polgar, P. B. van Niel, and L. Zechmeistsr, Arch. Biochem., 1944, 5 , 343.29 A. Manten, " Phototaxis, Phototropism and Photosynthesis," Dissertation,30 P.W. Carter, L. C. Cross, I. M. Heilbron, and E. R. H. Jones, Biochem. J., 1948,31 M. Hartmann, F. G. Medem, R. Kuhn, and H-J. Bielig, 2. Naturforsch., 1947.32 R. Kuhn and K. Wallenfals, Ber., 1939, 72, 1497; 1940, 73, 458; 1942, 75,33 D. M. Steven, J . exp. Biol., 1948, 25, 369; 1949, 28, 295.Univ. Utrecht, 1948.43, 349.24,330.407248 BIOCHEMISTRY.colour pattern is important, but whether the carotenoids are essential forother more physiological processes during the larval period is doubtful.Some insects do not appear to need carotenoids or vitamin A,34935 butothers contain various carotenoids so distributed about the body as tosuggest that they may be functional. The integument of locusts 36 (Locustamigratoria migratorioides R and E' and Schistocerca gregaria Forsk) contains@-carotene and free astaxanthin.Both pigments also occur in the eyes andthe wings, astaxanthin in the wings as a protein complex. Only @-caroteneis found in the fatty tissues, blood, and eggs 37 of locusts and the grasshopperblelanoplus bivattus Solitary and gregarious locusts show nocharacteristic differences in carotenoid content or distribution. Newlylaid eggs contain @-carotene which disappears as astaxanthin appears duringincubation. In the early hopper stages astaxanthin accounts for 70% ofthe total carotenoids but in the mature insect less than 30% is accountedfor in this way.38 The blood is bright green and carotene (present in highconcentration) is the only pigment; it must occur as a protein complex.Locusts contain no vitamin A and, as in other organisms lacking the vitamin,astaxanthin seems to be the key substance in visual processes.36Esterified astaxanthin occurs in the hypodermis of the lobster Hlomarusvulgaris Edw.and the prawn Nephrops norvegicus L. The carapace seemslike the eggs to contain unesterified astaxanthin; the ova contain mainlythe greenish astaxanthin-protein, ovoverdin. The lobster hepatopancreascontains P-carotene as the only carotenoid and that in very small amount:lbut vitamin A is present.42Northern krill (Meganictiphunes norvegica and Thysanoessa inerrnis)contain astaxanthin and very little p-carotene, but pre-formed vitamin Ais present in appreciable amount.43 The common shrimp Crangon vuEgarisand other crustacea contain small amounts of vitamin A.The whaleswhich feed on krill ingest large amounts of vitamin A and relatively little@-carotene.A study of carotenoids and vitamin A in frogs (Ram temporaria) through-out the life-cycle reveals a complicated picture.44 Young tadpoles containchlorophyll (from undigested food) and carotenoids. At first, xanthophyllsaccumulate in the body more quickly than carotene (which undergoes someconversion into vitamin A) but just before metamorphosis the rates ofstorage are more nearly equal. During metamorphosis the weight decreases84 C. M. McCay, Physiol. Zool., 1938, 11, 89.35 R. E. Bowers and C. M. MCay, Science, 1940, 92, 291.36 T. W. Goodwin and S. Srisukh, Biochem. J., 1949,45,263.37 R. Chauvin, Ann.SOC. ent. Fr., 1941, 110, 133.3s T. W. Goodwin, Biochem. J., 1949, 45,472.39 J. 3%. Grayson, Iowa State CoEE. J . Sc., 1942, 17, 69.J. M. Grayson and 0. E. Tauber, ibid., p. 191.41 T. W. Goodwin and S. Srisukh, Biochem. J., 1949, 45, 268.*% T. B. Nielands, Arch. Biochem., 1947, 13, 415.48 S. K. Kon and S . Y. Thompson, Biochem. J . , 1949, 45, xxxi.44 R. A. Morton and G. D. Rosen, ibid., p. 612MORTON: CAROTENOIDS, VITAMIN A, AND VISUAL PIGMENTS. 249and the carotenoids disappear unselectively. Ram tempmaria formvitamin A, 45 but some other frog species appear to form vitamin A,; 46indeed, Wald47 has recorded a sharp transition a t metamorphosis fromporphyropsin (vitamin A,) eyes to rhodopsin (vitamin A,) eyes in thebullfrog Rana cutesbiana.This does not apply to all frog species.48 Adultfrogs store " xanthophyll," carotene, and vitamin A in the liver and thekidneys : the amount of vitamin A in the eyes and kidneys is relativelylarge. Carotenoids, especially xanthophylls, are freely stored in the skinand, a t certain seasons, in the fat-bodies. The deposition of carotenoids inthe ovaries is so large that marked difference results between the sexes incarotenoid storage and utilization, but reproduction also drains the carotenoidreserves of the male.Such distribution studies in animals may be no more than preliminaryto the elucidation of function. The results depend upon superimposedpatterns of intake, assimilation, storage, and utilization of precursors andmetabolites, and of enzyme capacities and " detoxication '' processes.Here, the provitamin A role is clear, as are the photo-receptor functionsalready referred to ; carotenoids play several parts in reproductive processes,and in many respects they confer biological advantages a t concentrationlevels higher than those associated with indispensability.Only a beginning has been made in these comparative studies, and withregard to modes of action and the specificity of structure in relation to functionmuch remains to be done.Some of the difficulty arises from the maskingeffect of ecological variables ; carotenoid accumulation indeed often appearsto be physiologically fortuitous, or a t least not fundamentally significant.Vitamin-A Activity.-The definition of the unit of vitamin A (see p.250)as 0.3 pg. (potency of vitamin-A, alcohol, 3.33 x lo6 i.u./g.) makes p-carotene half as potent, weight for weight (potency of all-trans-@-carotene1.66 x lo6 i.u./g. from the definition 0.6 pg. for the unit of provitamin Aactivity).The liver reserves are retained durifig hibernation.This implies under appropriate conditionsin vccoC40H56 - c20H28x C20H28yif fission occurs a t the central double bond, only half of the p-carotenemolecule finally yielding the vitamin. The aldehyde Cl9H2,*C€€O is readilyreduced to vitamin A, in vivo and could well be an intermediate.These considerations point to the formation of vitamin A, as the generalmethod by which the carotenoids exert their growth-promoting action.The fact that the acid C,,H,,*CO,H 50 and the ether C,,H2,*CH,*OMe 51, 5245 A.E. Gillam, Biochem. J., 1938, 82, 1496.4~ E. Lederer and F. H. Rathmann, ibid., p. 1252. *' G. Wald, The Harvey Lectures, 1946, 41, 117.48 M. Lovs and R. A. Morton, unpublished observation.4s J. F. Arens and D. A. van Dorp, Nature, 1946, 151, 190.50 I. M. Sharman, Brit. J. Nutrit., 1949, 3, viii.ti1 A. R. Hanze, T. W. Conger, E. C. Wise, and D. I. Weisblat, J . Amer. Chem. Soc.,5a 0. Isler, M. Kofler, W. Euber, and A. Ronco, Experientia, 1946, 2, 31.1948, 'SO, 1253250 BIOCHEMISTRY.both exhibit very high growth-promoting power for rats deficient in vitaminA calls for caution, particularly as no sign of any substance akin to vitaminA, can be found in animals treated with the acid.53 The possibility cannotbe ignored that vitamin A and some of its derivatives may themselves beprecursors of an unknown degradation product responsible for some of thesystematic effects attributed t o the vitamin.Standards.-The International Conference held in London in 1949 underthe auspices of the World Health Organization recommended the adoptionof vitamin A acetate as the reference substance and defined the unit ofvitamin A activity as that shown by 0.344 pg.of the pure acetate. Stoicheio-metrically, this corresponds to 0.3 pg. of vitamin A, (C2,H,,*OH) the potencyof which is thus 3-33 x lo6 i.u./g. Since the intensity of absorption of theacetate at 328 mp. (in certain solvents) is Ei&. 1525, and 1750 for the alcoholat 326 my.the conversion factor is necessarily 1900: To use this factorfor converting observed E,l:m. values for oils and concentrates into i.u./g.is, however, legitimate only when the absorption spectrum of the sample isdemonstrably free from any irrelevant contribution at 326-328 mp.The p-carotene standard, in use since 1934, is to be retained as a yardstickfor provitamin A activity only; its main use will be in the determinationof p-carotene but i t will also be of service in relating provitamin A activityto stereochemical configuration. The preparation of the purest @-caroteneand of stable solutions in oil is difficult and the continued availability 54of the standard preparation will be welcomed.The problem of vitamin-A standardization has now probably been solvedand a brief review of its history may be opportune.The need for a referencestandard was evident in 1931; at that time carotene and vitamin A wereknown to be distinct substances each capable of curing or preventingavitaminosis A, but only carotene had been obtained in crystalline form.The “ unit ” was therefore defined as 1 pg. of carotene. By 1934 a-caroteneand &carotene had been differentiated, and the original specimen of caroteneshown to be heterogeneous. The unit was then re-defined as 0.6 Vg. ofpure p-carotene so as to preserve continuity, and a fresh reference materialwas brought into use.A considerable number of vitamin-A-containing oils had been assayedby the growth test on rats with parallel experiments using the growthresponse to P-carotene in known amounts.The intensity of absorption inthe ultra-violet (Ei?m. a t 328 mp,) had been determined for each fish liveroil tested biologically and it was found that by multiplying by 1600 theEi& value (observed on rich oils or on the-unsaponifiable fraction of pooroils) results agreeing closely with biological assays were obtained. In theU.S.A., however, a conversion factor of 2000 was preferred to 1600. Theuse of alternative conversion factors led t o much difficulty, mitigated bythe tacit acceptance of the E value as the measure of potency.The situation was clarified by concerted biological assays on crystalline63 Unpublished observations, Reporter’s laboratory.64 From the Director of Biological Standards, National Institute of Medical ResearchMORTON : CAROTENOIDS, VITAMIN A, AND VISUAL PIGMENTS.251vitamin A and the acetate, and by the use of photo-electric spectrophoto-meters. The potency of vitamin A in terms of the @-carotene unit was foundto correspond with a conversion factor between the limits 1800 (Britishworkers) and 1900 (American workers).It had been shown 55 that the original conversion factor of 1600 wasempirically satisfactory for gross i3:& values on oils of moderate to highpotency uncorrected for irrelevant absorption. A simple geometricalprocedure for obtaining corrected E values is widely agreed to be ~erviceable.~~The U.S. Pharmacopmia adopted in 1948 a new reference standardpreparation (labelled 10,000 i.u./g.) consisting of vitamin A acetate in oil,and showing E:Fm.a t 328 mp., 5.23. The 1949 International Conference 57recommended the general use of such a preparation for which a conversionfactor of 1900 is necessary.Provitamin-Apotency and vitamin-A potency cannot be regarded as necessarily inter-changeable or additive. Biological assays represent the combination of(a) provitamin-A or vitamin-A content and (6) the availability to theanimal of that content as compared with the availability of the standardpreparation.In determining the vitamin-A content of fish-liver oils and concentrates,the E value (at 328 mp. where the vitamin absorption is maximal) cancorrectly be multiplied by 1900 (to give i.u./g.) when absorption a t thatwave-length due to substances other than vitamin A has been eliminatedor allowed for.The standard preparation can be used to fix the correctabsorption curue by plotting E values between 250 mp. and 380 mp. on a,scale where Em,,. = 1-00. If the curve for an oil under study is plotted inthe same manner irrelevant absorption will bring about obvious distortionas compared with the standard curve. The curve may then be correctedgeometrically and the reduced E,,,.multiplied by 1900, or the sample maybe purified by chromatographic or other methods. A new departure is thusto be noted in the use of a standard preparation; in addition to its directuse as a biological standard it provides a test for absorption curves distortedby irrelevant absorption and applicable to whatever type of spectrophoto-meter is in use.This is, of course, not the same as using it to test the correctbehaviour of the instrument; that is best ascertained by using a standardglass or a simple solution such as potassium chromate.Biological Standardization.-The usual procedure using growth responseshas been supplemented by a histological method of assessing the degree ofmyelin degeneration shown in vitamin-A deficien~y.~~ Microscopic lesionsAttention needs to be drawn, however, to certain pitfalls.5 5 R. A. Morton and A. L. Stubbs, Biochem. J., 1948, 42, 195.5 6 Idem, Analyst, 1946, 71, 356.5 7 Expert Committee on Biological Standardization, Bulletin World HealthOrganization 1950. (Recommendations accepted August, 1949, and now official.)In this country the standard preparations are distributed by the Director of BiologicalStandards, National Institute of Medical Research ; next issue April lst, 1960.ii8 H.K. Coetzee, Biochem. J., 1949, 45, 628252 BIOCHEMISTRY.in the brains of chicks deficient in vitamin A have also been noted.60Coetzee’s method when applied to a range of fish-liver oils led to estimatesof potency which agreed very closely indeed with those based on the Evalues at 328 mp. corrected by the procedure of Morton and Stubbs.56Considerable work has been devoted to an attempt to use the liver storageof vitamin A as a biological-assay method.59 There is no doubt that themethod has possibilities particularly as the animal rejects to a large extentmaterials giving rise to great irrelevant ultra-violet absorption (e.9.thosepresent in some whale-liver oil preparations). The animal thus acts as a“ filter,” but the final assessment rests on spectrophotometric readings onthe liver unsaponifiable fraction from the experimental animal. Much willdepend on the anti-oxidants present in the oil under study.61-68 Thewhole problem of storage, in relation to dose levels of vitamin, propertiesof the “ carrier ” oil, distribution of storage between Kupffer cells and trueliver cells, and permanence or otherwise of the vitamin store, is very com-plicated and bio-assay methods based on this approach need to be usedwith circumspe~tion.~~Special Analytical Prob1ems.-Vitamin A in many samples of whale-liver oil is difficult to determine because of the presence of other absorbingsubstances.These include kitol,?O a divitamin A [C,,€€,,(OH),] showingLax. at 286 mp. but lacking vitamin-A potency. This substance occurs insome whale-liver oils as a diester which has been obtained fairly p ~ r e . ~ 1A good method of obtaining a vitamin-A fraction by Chromatography onalumina of the unsaponifiable matter of whale-liver oil has been worked0 ~ t , 7 ~ and an alternative method making use of chromatography of the wholeoil on weakened alumina gives similar results more r e a d i l ~ . ~ lThe existence of neo-vitamin A may give rise to further complication^.^^neo-Vitamin A, is said to be a stereoisomer of the all-trans-vitamin A,. Itmelts a t 58-60’ as compared with 62-64’ for the ordinary form, and itsabsorption maximum (E;Trn* at 328 mp., 1645) ’* is slightly different from5s K.Guggenheirn and W. Koch, Biochem. J . , 1944, 38, 261.So F. B. Adamstone, Arch. Path., 1947, 43, 301.6 1 F. Week and F. J. Sevigne, J . Nutrition, 1949, 39, 233.62 Idem, ibid, p. 251.63 T. Moore, A. J. P. Martin, and K. R. Rajogopal, “Vitamin E Symposium,”64 A. W. Davies and T. Moore, Nature, 1941, 147, 794.65 T. Moore, Vit. and Horm., 1945, 3, 12.6 8 HI. C. D. Hickman, P. L. Harris, and M. R. Woodside, Nature, 1942, 150, 91.87 P. L. Harris, M. W. Kaley, and K. C. D. Hickman, J . BioZ. Chem., 1944,152,313.68 K. C. D. Hickman, M. W. Kaley, and P. L. Harris, ibid., pp. 303, 321.69 Unpublished work by A. D. MacQueen and J.Glover, Reporter’s laboratory.70 J. G. Baxter, F. B. Clough, H. 1%. Kascher, and C. D. Robeson, Science, 1947,7 1 R. K. Barua and R. A. Morton, Biochem. J., 1949, 45, 308.72 N. T. Gridgeman, J. P. Savage, and G. P. Gibson, Analyst, 1948, 73, 662.7 3 J. G. Baxter and C. D. Robeson, J . Amer. Chem. SOC., 1947, 69, 136.74 J. D. Cawley, C. D. Robeson, L. Weisler, E. M. Shantz, N. D. Embree, and J. G.Heffer, Cambridge, 1939.105, 436.Baxter, Science, 1948, 107, 346MORTON : CAROTENOIDS, VITAMIN A, AND VISUAL PIGMENTS. 253that of the all-trans-form (E::&. a t 326 mp., 1750). Its biological activitymay be slightly lower than that of all-trans-vitamin A,. Synthetic products 74and many fish-liver oils 75 contain considerable proportions of neo-vitaminA, as judged by an analytical procedure making use of the different ratesat which neo-vitamin A and all-trans-vitamin A combine with maleicanhydride.It is perhaps early to say whether the existence of neo-vitamin A requiresreconsideration of analytical methods, but it is very unlikely that muchwill be gained by routine examination for isomers.Vitamin-A Requirements-of Adult Humans.---The full report 76 appearedin 1949 of an experimental study of vitamin A deprivation in man, carriedout during the War by a British team of workers.Conscientious objectorswho volunteered to act as subjects were kept on a diet very low in caroteneand vitamin A but otherwise adequate, until (in some of them) unmistakablesigns of vitamin-A deficiency appeared.The amount of (3-carotene orvitamin A needed to remove the symptoms was then determined.The Report is long and technical and the Reporter, as one who participatedin the work, is conscious that any short summary is inadequate. Thevolunteers (20 young men and 3 young women) were given a diet whichprovided a t most 42 pg. of ( ( carotene” per day and was shown byfeeding tests on rats to possess negligible vitamin-A activity. The wholeexperiment lasted over two years (1942-1944).Five subjects were given throughout the experiment about 5000 i.u.of @-carotene daily in various forms, and two others were given 2500 i.u.of vitamin A per day in the form of a diluted concentrate. Sixteen subjectsreceived the unsupplemented diet until they showed a serious drop (orderof 50%) in plasma vitamin A and a considerably delayed dark-adaptation,or in a few cases until they dropped out of the experiment.The manifestlydepleted subjects were given either p-carotene or vitamin A.The best techniques available under war-time conditions were used fordetermining capacity for darlr-adaptation and also total carotenoids,(‘carotene,” and vitamin A in food, blood, and faxes. Clinical tests,including blood counts, skin biopsies, audiometric tests, and slit-lampexaminations were made regularly together with psychological appraisals.Although some of the work could today be improved upon as a result ofpost-war re-equipment, the investigation as a whole was a most successfuleffort in co-operative research which it would be difficult to repeat.The first change caused by the deficient diet was a decrease in plasmacarotenoids from about 0.9 pg.to about 0.24 pg. per ml., little of the persistingpigment being “ carotene.” A steady state was reached after 3 monthsand no marked change was noticeable during the next 5 months. Then the75 P. Meunier and J. Jouannateu, BUZZ. SOC. Chim. biol., 1948, 30, 260.7 6 A Report of the Vitamin A Sub-Committee of the Accessory Food FactorsCommittee of the Medical Research Council (compiled by E. M. Hums and H. A. Krebs),M.R.C. Special Report, Series No. 264, H.M.S. Office, 1949. The report gives the namesof sl1 the workers who participated in the experiment264 BIOCHEMISTRY.plasma-vitamin-A levels (normally of the order 1.2 i.u./ml.) began to fallin 10 out of 16 subjects and later reached 0.5 i.u./ml.in 4 men.Dark-adaptation tests showed that the normal cone-rod transitiontime varied between 5 and 12 minutes and the normal final cone-rodthreshold between 1-37 and 2.3 log mp. lamberts. Three subjects showedincreased transition times (up to 33i minutes) and had low plasma-vitamin-A levels at the critical time. One of them received 1300 i.u. ofvitamin A in oil daily and his capacity for dark-adaptation was graduallyrestored to a level which could not be improved by larger doses of vitamin A.With a daily dose of 750 pg. (1250 i.u.) of @-carotene in oil, one depletedsubject showed an increase in plasma-vitamin-A but a worsened cone-rodthreshold. Another depleted subject given 2500 i.u.per day of p-carotenein oil showed improvement by both criteria. After 5$ months of supple-mentation the first ( ( carotene ’’ subject (1250 i.u. per day) improved markedlyon transfer to an unrestricted diet, whereas the other subject (admittedlynot quite so markedly depleted) recovered completely in 3 weeks with 2500i.u. per day of @-carotene.Two subjects given for 14 and 17 months, respectively, a prophylacticdose of 2300 i.u. per day of vitamin A in oil were maintained in vitamin-Abalance although the plasma levels subsequently rose on an unrestricteddiet.The great majority of the clinical examinations showed no significantdifferences between the deprived and non-deprived groups.In all cases a variable proportion of the carotene administered appearedin the fzeces, and the part not excreted is called the maximum effectivedose.The average amount of carotene excreted, expressed as a percentageof the measured intake, was about 75 for carrots, 59 and 73 for cabbage a ttwo different dosages, 57 for homogenised spinach, 29 for carotene inmargarine, and 26 for carotene in arachis oil.In the prophylactic tests with carotene given in different ways the effectivedose varied from 1250 to 3700 i.u. daily and except for a doubtful period atthe lower level no significant signs of depletion appeared. This was notsurprising as 71 civilians accidentally killed in 1941-44 possessed liverstores of the order of 500,000 i.u. This reserve “ buffers ” the plasma-vitamin-A level making it unresponsive to short-term marginal intake ofvitamin A or provitamin A.The minimum requirement provided wholly as preformed vitamin Ais near 1260 i.u.daily with 2500 i.u. providing a margin of safety. Similarlythe requirements of p-carotene are 1500 i.u. daily with 3000 i.u. for safety,but if the recommended intake is corrected for incomplete absorption, thegross figures would be : for carotene contained in cooked carrots 12,000,cabbage or spinach 7500, p-carotene in oil 4000 i.u. per day (perhaps 7500i.u. daily for mixed foods).The Report stresses that the results apply mainly to healthy youngadult males, and it is impossible to say what modifications should be madefor children, pregnant and lactating women, and diseased persons.ThMORTON : CAROTENOIDS, VITAMIN A, AND VISUAL PIGMENTS. 255results, moreover, do not provide an infallible guide for assessing the adequacyof a diet in nutritional surveys.In some ways the most important finding is that the lengthened cone-rodtransition time emerges as the least equivocal and most reproduciblymeasurable test of vitamin-A deficiency, and the view that rhodopsinregeneration is conditioned by vitamin-A supply is fully borne out.Conversion of Provitamins into Vitamins A.-An increase in the liverstore of vitamin A, as a result of ingesting carotene, was established in1929.77 The idea that the conversion takes place in the liver was widelyentertained but the evidence was unsatisfactory. None of the experimentswith liver tissue and colloidal solutions of carotene in vitro was unequivocallypositive and many were negative.Drummond and his colleagues carriedout experiments in vivo all of which were negative in the sense that conversionin the liver could not be d e m o n ~ t r a t e d . 7 ~ ~ ~ Vitamin A cannot be detectedby fluorescence microscopy 81 in the liver of depleted rats after parenteraladministration of carotene although there is no doubt that the hydrocarbonreaches the liver.82The first pointer to a site other than the liver was the discovery of largea-nnounts of vitamin A on the lining of the intestines of many kinds offishes; 8 3 ~ ~ 4 this was at once followed up commercially but its theoreticalimplications were not, partly because the phenomenon does not occur inmammals or even in all fishes.85It is now clear that injected carotene may be freely stored in the Kupffercells of the liver but in the rat conversion there into vitamin A is on a scaletoo small to be demonstrable.Deuel's group 86 has shown that, irrespectiveof the route, parenterally administered carotene is ineffective and that theliver may be rich in carotene without any relief of the symptoms of avita-minosis A. Incubation of the intestines with colloidal carotene failed toshow Conversion into vitamin A, but in spits of this the intestine was latershown to be the site of the p r o ~ e s s . ~ ~ - ~ ~The Liverpool group had been impressed by the fact that some speciesdo not naturally store carotenoids; thus in sheep and goats little caroteneis found in blood plasma, milk fat, or body fat in spite of a large intake infood. This was a serious obstacle to accepting the liver as the site of con-7 7 T.Moore, Riochem. J., 1930, 24, 692.79 J. C. Drummond, H. P. Gilding, and R. J. MacWalter, J. Physiol., 1934, 82, 75.J. L. Rea and J. C. Drurnrnond, 2. Vitaminforsch., 1932, 1, 177.J. C. Drummond and R. J. MacWalter, ibid., 1935, 83, 236.H. Pepper, Arch. Path., 1941, 31, 766.82 A. Vinet, M. Plessier, and Y. Raoul, Bull. SOC. Chim. biol., 1943, 25, 87.J. A. Lovern, J. R. Edisbury, and R. A. Morton, Nature, 1937, 140, 276.** J. A. Lovern, R. A. Morton, and J. Ireland, Biochem. J., 1939, 33, 325.8 5 J. A. Lovern, T. H. Mead, and R. A. Morton, ibid., p. 338.8 6 E.L. Sexton, J. W. Mehl, and J. Deuel, jun., J. Nutrition, 1946, 31, 299.8 7 S. Ball, J. Glover, T. W. Goodwin, and R. A. Morton, Biochem. J., 1947, 41,xxix.F. H. Mattson, J. W. Mehl, and H. J. Deuel, Arch. Biochem., 1947, 14, 65.8B C. F. Wiese, J. W. Mehl, and H. J. Deuel, ibid., 1947, 17, 75256 BIOCHEMISTRY.version. No carotene could be detected in portal or systemic blood ofsheep or goats given large doses of carotene direct into the du~denum.~OThe conversion of vitamin-Al-aldehyde (p. 249) into vitamin A wasshown to occur in rats in the intestinal wall.86,g1 This was followed bydirect proof of the conversion of carotene into vitamin A in uiuo and inv i t ~ o . ~ ~ The finding was soon confirmedg3 and extended to pigs in a fulls t ~ d y .~ 4 A rise in the concentration of vitamin A in thoracic lymph in thegoat after feeding it with @-carotene was e~tablished.~~ Finally, it wasshown that carotene could be converted into vitamin A in rats in which theliver was isolated by a ligature on the portal vein.96 All this makes itcertain that the intestinal wall is the main, and possibly the sole site of theprovitamin + vitamin conversion in mammals.Thnoid Activity and Vitamin A,--Contradictions in the literatureconcerning the interrelation between the thyroid hormone and vitamin Ahave been largely explained.Thyroidectomized animals depleted of vitamin A may be cured ofxerophthalmia by orally administered carotene 97 but not by injectedcarotene.98, g9 That is not now difficult to understand (see p.255), but theobservation, if it can be reproduced, that carotene appears in the milk ofthyroidectomized goats 1, may be more significant. When liver storageof vitamin A was used as a measure of carotene conversion, desiccatedthyroid gave an increase and thiouracil a decrease compared with controls,whereas with a mixture of the thyroactive and antithyroid substancesnormal storage o ~ c u r r e d . ~ , ~ At a much lower level of carotene intakesimilar effects might be expected when the growth test is used to assess theefficiency of conversion. Thiouracil not only retards the rate of depletionof hepatic stores of vitamin A but also has itself a growth-inhibiting actioncorrectable by adding desiccated thyroid but not by vitamin A ; the amountof carotene needed to produce half the maximal growth in both the controlsand the thiouracil-treated animals was the same.This experiment pointsaway from the idea that thiouracil inhibits the carotene _t vitaminconversion.O0 T. W. Goodwin, A. D. Dewar, and R. A. Gregory, Biochem. J., 1946, 40, x.O1 J. Glover, T. W. Goodwin, and R. A. Morton, Biochem. J., 1947, 41, xv.92 Idem, ibid., 1948, 43, 512.O3 F. H. Mattson, J . Biol. Chem., 1948, 176, 1467.O4 S. Y. Thompson, J. Ganguly, and S. K. Kon, Brit. J . Nutrition, 1947,1, v ; 1949,O 5 T. W. Goodwin and R. A. Gregory, Biochem. J., 1948, 43, 505.96 R. F. Kraus and H. B. Pierce, Arch. Biochem., 1948, 19, 145.D7 R. E. Remington, P. L. Harris, and C. L. Smith, J . Nutrition, 1942, 24, 597.Q8 V.A. Drill and A. P. Truant, EndocrinoEogy, 1947, 40, 259.Q9 J. M. Canadell and F. G. Valdescasas, Experientiu, 1947, 3, 35.T. Fellenberg and F. Greuter, Biochem. Z., 1932,253, 42.F. Fasold and E. R. Heidemann, 2. ges. ezp. Med., 1933, 92, 53.R. M. Johnson and C. A. Baumann, J . Biol. Chem., 1947,171, 513.B. Kelley and H. C. Day, ibid., 1948, 175, 163.C. E. Wiese, J. W. Mehl, and H. J. Deuel, ibid., p. 21.3, 50MORTON: CAROTENOIDS, VITAMIN A, AND VISUAL PIGMENTS. 257Recent work casts doubt on the observation that hypothyroid goats giveyellow milk, indeed no carotene was found in the blood or the milk.'Rabbits on a carotene-rich diet and given large doses of thiouracil showedno carotene in the systemic blood. Thiouracil has no effect on the stabilityof carotene in witro, but thiouracil-treated rats excrete a larger fraction ofthe dose of (3-carotene (under different dietary conditions) than do untreatedsnimals.899 This shows that the anti-thyroid drug reduces caroteneabsorption, which accounts for the previously observed decreased storage ofvitamin A.3 The growth-test experiments were perhaps a t dose levelsbelow the threshold for interference with absorption.The claim lo thatthyroactive substances influence the enzymic conversion of carotene intovitamin is probably unjustified.8Mobilization of Liver Reserves of Vitamin A-Pfasma concentrationsof free vitamin-A alcohol rise quite slowly with large increases in the totalliver store of vitamin A, after heavy doses of vitamin A.A much closerrelationship obtains between plasma-vitamin-A concentration and the freevitamin A of the liver.ll The liver store is distributed over the Kupffercells and the true liver cells, and the former appear to contain only the esterwhereas the latter contain some alcohol. This agrees with the absence oflipases (and esterases?) from the Kupffer cells, and their presence in thetrue liver cells.13 It is not clear how vitamin-A esters are liberated fromthe Kupffer cells. It is possible that frequent small doses of vitamin Awill result in a more favourable distribution of the store than higher dosesat longer intervals apart. Much of a massive dose is probably immobilizedin the phagocytic Kupffer cells. This line of thought has importantimplications in the therapeutic use of vitamin A.Claims that ethyl alcohol ingestion mobilizes vitamin A fromliver to blood and that adrenaline affects vitamin-A levels have not beenconfirmed, 149 15Physiology of Vitamin A.-In rats, metaplasia of the epithelium of theurinary tract is an early result of vitamin-A deficiency, and i t appears thatmucosie become avitaminotic because the mitochrondia are low in vitamincontent.16 Cessation of weight increase is considered to be secondary tomucosal dysfunction.In growing chickens l7 the typical post-mortem signs-urates in the kidneys, nodules on the oesophagus, etc.--are rarely seenR. M. Johnson and C . A. Baumann, Fed. Proc., 1948, '7, 290.V. R. Smith, R. P. Niedenneiser, and L. Schultz, J .Animal Sci., 1948, 7 , 544.H. R. Cama and T. W. Goodwin, Biochem. J., 1949, 45, 248.s Idem, ibid., p. 317.lo T. A. Balaba, J. Physiol. U.S.S.R., 1940, 29, 318.l1 J. Glover, T. W. Goodwin, and R. A. Morton, Biochem. J., 1947, 41, 101;lS J. GIover and R. A. Morton, Biochem. J., 1948, 43, Proc. xii.l4 See ref. 76.l5 T. W. Goodwin and A. A. Wilson, Biochem. J., 1949,45, 370,l7 M. W. Taylor and W. C . Russell, Poultry Sci., 1947, 26, 234.1948, 43, 512.M. Bracco and H. v. Euler, Arkiv IZemi, Min., Geol., 1948, A , 26, 1.REP.-VOL. XLVI. 258 BIOCHEMISTRY.before the last stages of deficiency, but inco-ordination possibly caused bybony overgrowths with sequele on nervous tissue occurs early. Thesesigns recall Mellanby’s observations on dogs l8 and Wolbach and Bessey’son rats.lg Vitamin-A deficiency exacerbated cecal coccidiosis when itoccurred in chicks.20 The earliest sign of deficiency was a slight reddeningabout the eyes, followed rapidly by secondary infection.The minimumrequirement of laying hens for provitamins A for good egg production andhigh hatchability is rather high (ca. 3000 i.u./lb. of feed); if it is provided,the plasma-vitamin A is of the order of 1.5 i.u./ml.Liver stores of vitamin A are depleted more quickly in rats growingnormally than in those stunted by inadequacies of calories, aneurin, ortryptophan. Halving the growth rate is more important for vitamin-Aretention than a threefold increase in metabolic rate induced by desiccatedthyroid. In normally growing rats, a decrease in liver reserves is acccm-panied by a rise in kidney vitamin A, but this does not happen in rats whosegrowth was restricted during the depletion period.21Rats deficient in vitamin A show symptoms resembling those of scurvy.22Blood ascorbic acid is a t least halved23 and the adrenals show considerablehypertrophy with lowered vitamin4 content.The striking effect firstobserved by Moore 2 4 7 2 5 that vitamin-A storage is enhanced by an adequatevitamin-E intake is complemented by the observation on humans thatblood-vitamin-E levels rise significantly after prolonged high dosage withvitamin A.26 Similar rises in plasma cholesterol occurred but carotene andvitamin-C levels were unaffected.Vitamin A is much more effectively stored when given dispersed inaqueous media than in oily solution.27~ 28 Lecithin enhances absorptionof carotene and of vitamin A.29 With extremely high intake and storage,hypervitaminosis A becomes a reality.3O The characteristic lesions bearsome resemblance to those found in human and in experimental scurvy.It will be seen that the elucidation of the mode or modes of action ofvitamin A is distinctly hampered by a plethora of physiological evidenceand by vitamin interrelations.The co-enzymic role which might clarifythe situation is still to be found.E. Mellanby, J . Physiol., 1941,99, 467.l* S . B. Wolbach and 0. A. Bessey, Arch. Path., 1941, 91, 599.2o M. W. Taylor, J. R. Stern, and W.* C. Russell, Poultry Xci., 1947, 26, 243.21 R. M. Johnson and C.A. Baumann, J . Nutrition, 1948,35, 703.2z J. Mayer and W. A. Krehl, Arch. Biochem., 1948, 16, 313.23 G. Johnson, A. L. Obel, and K. Sjoberg, 2. Vitaminforsch., 1942, 12, 300.24 T. Moore, A. J. P. Martin, and K. R. Rajogopal, “Vitamin E Symposium,”25 T. Moore, Biochem. J., 1940,34, 1321.26 J. T. v. Bruggen and J. V. Straumfjord, J . Lab. Clin. Med., 1948, 33, 67.27 A. E. Sobel, M. Sherman, J. Lichblan, S. Snow, and B. Kramer, J . Nutrition,28 H. Popper and B. W. Vole, Proc. SOC. exp. biol., 1948, 68, 562.29 G. C. Esh and T. B. Sutton, J . Nutrition, 1948, 36, 391.30 T. Moore and Y . L. Wang, Biochem. J., 1945, 39,222.Heffer, Cambridge, 1939.1948, 35, 225MORTON : CAROTENOIDS, VITAMIN A, AND VISUAL PIGMENTS. 259Biochemical Aspects of Vision.-The light receptors of the visual layerof the retina are called rods and cones but the implied difference in shapeis not clear-cut.Nocturnal animals have many more rods than cones butthe opposite is true for diurnal animals. During dark-adaptation, a highlyphotosensitive pigment accumulates in the rods but the cones are alwaysrelatively insensitive to light. With intensities of about 0.1 metre-candle,both types of receptor are in action; a t lower intensities the rods only area t work and a t higher intensities vision is mediated only by the cones. Therod pigment, visual purple or rhodopsin, reaches its maximum concentrationin man after about 45 minutes of dark-adaptation; very dim light is thenperceptible partly because of the sensitivity of the pigment and partlybecause many rods are connected via bipolar and ganglion cells to one opticnerve fibre.31The minimum perceptible intensity of light decreases as the timepreviously spent in darkness increases; the curve of intensity against timeshows a sharp break a t the cone-rod threshold and the cone-rod transitiontime.The discontinuity has been confirmed by electrophysiological methods.If very weak monochromatic radiations are used, a dark-adapted personcannot recognize colour-differences but the minimum perceptible intensitydepends upon the wave-length.For rod (or scotopic) vision and cone (or photopic) vision the luminositycurves are broad and show maxima a t 500 mp. and 560 mp., respectively.Photopic vision is not necessarily accompanied by colour vision.Rhodopsin may be extracted from retinas obtained by dissecting eyesin In solution it exhibits an absorption spectrum which agreesvery closely with the scotopic luminosity curve.The methods which yieldrhodopsin solutions (Amax. 500 mv.) from mammalian retinas result in theextraction of a related pigment porphyropsin (A,,,. 520-530 mp.) from theretinas of certain fresh-water fishes. A pigment iodopsin has been postulatedto account for the photopic luminosity curve.The Young-Helmholtz trichromatic theory of colour vision postulatedthree types of cones or three types of receptor per cone. Recent physiologicalresearches have enriched the evidence; thus Granit and his colleagueshave perfected electrophysiological methods of exploring the retina witha micro-electrode touching a single nerve-fibre from a ganglion cell on thevitreal surface, preferably using decerebrate animals with the cornea andlens excised.The second electrode is placed in contact with the sclera andthe currents obtained are amplified and recorded. The responses to mono-chromatic light are in the form of impulses, the frequencies of whichincrease with increasing intensity of monochromatic light. With eyes ofmany species a broad scotopic dominator curve ( hmax. 500 mp.) is obtained inthe dark-adapted state; but fresh-water fishes such as tench and carpshow Am,,. 530 mp. With light-adapted eyes the results vary from onenerve-fibre to another and from one species to another. Eyes of rats andred light.81 R.Granit, " Sensory mechanim of the retina," Oxford Univ. Press, 1947260 BIOCHEMISTRY.guinea-pigs show Amax. 500 mp. but those of frogs and cats exhibit a photopicdominator curve with Amax. 560 mp. Some nerve fibres produce a curvewith an inflexion near 600 mp., whilst others show modulator curves abouthalf as wide as the dominator curves. The following maxima were recorded :rat (few cones), modulators at 500 mp. and 610 mp; guinea-pig, 460, 500,530, and 600 mp.; frog, 450470, 530, 580, and 600 mp.; cat, 36% offibres, dominator 560 mp., 64% of fibres, 530 and 560 mp.; tortoise, conedominator 610 mp., modulator 540 mp.; carp and tench, cone dominator610 mp., modulators 540 and 650 mp.Granit 32 has obtained further evidence of modulator curves by selectivelight adaptation and by the use of polarizing currents.Hartridge 33 interprets a very wide range of bio-physical measurements asfollows : at least 7 types of cones can be differentiated according to theirspectral sensitivities; 3 types, responding mainly to blue, green, and redlight, respectively, are regarded as main receptors, and 3 subsidiary re-ceptors are complementary to the others; the different types are randomlydistributed except that clusters of similar cones may occur ; sufficientlynarrow pencils of white light or filtered light may stimulate a cluster ofcones or possibly single cones, and fixation points may be recorded, eachcorresponding with a rather narrow strip of the visible spectrum.Manyfindings 34, 35 are difficult to reconcile with the simple trichromatic theory,and the hypothesis of additional receptors gives more “ elbow room ”without necessarily making it easier to compel assent.Excellent reviews36 of recent advances in the physiology of vision areavailable, and the foregoing paragraphs are intended mainly to drawattention to the challenge to chemists in that the action spectra of thedominators and modulators present something very definite to be accountedfor.Rhodopsin.Visual purple is a conjugated protein, the prostheticgrouping of which is in some way related chemically to vitamin A, andporphyropsin seems to be similarly related t o vitamin A,. Rhodopsinoccurs mainly in the outer segments of the rods; these are often easilydetached by shaking the retinas in d i n e .A good method is to dissectout retinas in a weak red light and shake them in a 40% (w/v) solution ofsucrose ; 37 on centrifuging, the rods remain in suspension. Dilution withwater followed by re-centrifuging throws down the rods, which are thenhardened with alum. After the liquor has been poured off and the residue32 B. Gernandt and R. Granit, Nature, 1947, 159, 806.33 H. Hartridge, Phil. Trans., 1947, 232, 592.34 R. W. Pickford, Nature, 1948, 162, 684.35 E. N. WilImer and W. D. Wright, Nature, 1945, 156, 119.as E. N. Willmer, “ Retinal Structure and Colour Vision,” 1947, London ; W. D.Wright, ‘‘ Researches on Normal and Defective Colour Vision,” 1946, London ; “ Docu-menta Ophthalmologica, Advances in Ophthalmology,” 1949, Vol.3, Junk S-Gravenhage,Edited by F. P. Fisher, Utrecht, A. J. Schaeffer, and A. Sorsby. M. H. Pirenne,“ Vision and the Eye,” 1949, Chapman & Hall.31 Z. Saito, Tohoku J . Exp. Med., 1938,32,432MORTON : CAROTENOIDS, VITAMIN A, AND VISUAL PIGMENTS. 261washed, the rhodopsin dissolves on treatment with a 1% solution ofd i g i t ~ n i n . ~ ~ The best preparations show it nearly symmetrical absorptioncurve with Amax. 500 my.; the intensity of absorption at 400 mp. is aboutone quarter of that at 500 mp. and there is a weak maximumat 340-350mp.393 40 The absorption rises steeply in the ultra-violet, showing “ protein ”absorption (due to tyrosine and tryptophan). The maximum (at 275 mp.) maybe as low as 2-2 times 393 40 the intensity of the 500 mp.peak, but is usuallymuch more intense because it is difficult to eliminate colourless contaminatingproteins. The molecularweight has been estimated to be 270,00041 but that figure may needThere is so far no fully satisfactory test of purity.revision.Cepholopsin. Cepholopsin is an interesting analogue of rhodopsinobtained from the eyes of squids (Loligo v u t g a r i ~ , ~ ~ Loligo pe~lii).*~ It isa light-stable red pigment (Amax. 495 mp.) which becomes light-sensitive ontreatment with formaldehyde, and retinene is released.43 However, St.George and Wald 44 applied to squid retinas the normal method for extractingrhodopsin. The solution showed maxima at 490, 365 (weak), and 279 mp.“ In the light it undergoes a photochemical change followed by a ‘ dark ’reaction, comparable with the transformation of rhodopsin to lumi- andmeta-rhodopsin.The squideye seems to contain both free and bound retinene.45Photochemical Changes. Exposure of isolated retinas to light destroysrhodopsin, and vitamin A, is set free. Photochemical bleaching of rhodopsinsolutions can take place at very low temperatures, and a labile compound,transient o r i ~ n g e , ~ ~ , ~ ~ is formed. This material is unstable a t room tem-perature, and yields indicator yellow, which, as its name implies, is pH-sensitive (Amax. 360 mp. in alkaline solutions, 440 mp. in acid solutions).By extracting freshly-bleached retinas with light petroleum, Wald 489 49obtained a new carotenoid-like material which he called retinenel. I nchloroform solution it showed Lax.385-387 mp. and gave with the antimonytrichloride reagent a blue colour having Amax. 664 mp. Wald also obtainedretinene, by extracting bleached rhodopsin solutions. Porphyropsinsolutions similarly treated gave retinene2 (Lax. 405 mp. in chloroform,705 mp. with the antimony trichloride reagent).The two retinenes were obviously key substances to which Wald hadThe material is very similar to rhodopsin ”.3* K. Tansley, J . Physiol., 1931, 71, 442.39 G. Wald, ‘‘ Documenta Ophthalmologica,” 1949, VoI. 3, p. 94.40 F. D. Collins and R. A. Morton, Biochern. J., 1950, in the press.41 S. Hecht and E. G. Pickels, Proc. Nut. Acad. Sci. Wash., 1938, 24, 172.42 J. E.-Desrivihres, E.Lederer, and M.-L. Verrier, Compt. rend., 1938, 207, 1447.43 A. F. Bliss, J . Biol. Chern., 1948, 178, 563.4p R. C. C. St. George and G. Wald, Biol. Bull., 1949, 97, 248.45 G. Wald, J. Dwell, and R. C. C. St. George, Science, in the press.46 R. J. Lythgoe and J. P. Quilliam, J . Physiol., 1938, 94, 339.47 E. E. Broda and C. F. Goodeve, Proc. Roy. SOC., 1941, B, 130,217.48 G. Wald, J . Gen. Physiol., 1935-6, 19, 351.p9 Idem, ibid., p. 781262 BIOCHEMISTRY.attached valuable labels although neither could be obtained pure or inadequate quantity for characterization. The only plausible explanationof their spectra and colour tests was the hypothesis 50 that they wererespectively the aldehydes corresponding with vit.amins A, and A,.Thisidea was tested and ~onfirmed.~~Retinene, may conveniently be prepared by leaving vitamin-A alcoholin light petroleum over solid manganese dioxide at room temperat~re,~~Vitamin A,, free from vitamin A,, is not a t all readily accessible, but amixture of vitamins A, and A, may be oxidised similarly, and the tworetinenes separated by chr~matography.~~ Both substances have beenobtained crystalline and fully characterized.Spectroscopic Data for Vitamin A and Some Related Compounds.OscillatorCompound. Amax. (ml.1. Emax.. strength, f.* Solvent.Vitamin-A aIcohoI ............ 326 48,300 0-97 cyclohexaneVitamin-A acetate ............ 328 48,500 0-92 cyclohexaneVitamin A28 .................. 35 1 41,600 0.99 ethanolRetinene, ( C ~ O H ~ ~ O ) .........385 39,800 0.84 ethanolRetinene, (C,,H,,O) ......... 386 41,200 0.90 light petroleum* f = 4.31 x 1W8 ycdv = ca. 1.0. s[v is in wave numbers (crn.-l), s is the deoadic molecular extinction coefficient]The availability of retinene, (vitamin-A-aldehyde) in reasonable amountsmade possible experiments in which it was administered orally and parenter-ally to rats. Retinene, was found to be readily converted into vitamin A,by an enzymic reduction. The orally administered aldehyde is convertednearly quantitatively into vitamin A in the gut waIl.54 Retinene, is similarlyconverted into vitamin A,. Both aldehydes undergo Ponndorf reductionto give the vitamins.The retina contains an enzyme system which readily reduces retinene, ;the change, to vitamin A can be effected in vitro using coenzyme I andfructose 1 : 6-dipho~phate.~~ The change is reversible since a rabbit-liverDPN-specific alcohol dehydrogenase preparation in the presence of coenzymeI and pure vitamin A (dispersed by a detergent), together with bisulphiteor cyanide to “trap ” aldehyde, results in a 40% c0nversion.5~ Isolatedrods appear to contain the reductase.6o R.A. Morton, Nature, 1944,153, 69.61 R. A. Morton and T. W. Goodwin, ibid., p. 405.S. Ball, T. W. Goodwin, and R. A. Morton, Biochem. J., 1948, 42, 516.R. A. Morton, M. K. Salah, and A. L. Stubbs, Nature, 1947,159, 744.J. Glover, T. W. Goodwin, and R. A. Morton, Biochem. J., 1948,43,10, 109.6 5 G. Wald and R. Hubbard, J . Gen. Physiol., 1949, 32, 367.ti6 A.IF. Bliss, BioE. Bull., 1949, 97, 221MORTON : CAROTENOIDS, VITAMIN A, AND VISUAL PIGMENTS. 263In essentials the sequence is as follows :light 1 rhodopsin? transient orangeI IYindicator yellowI I retinene reductase \ $vitamin A + protein I__ retinene, + protein \ (DPN-PH + fructose 1 : 6-diphosphafx + dehydro-genase system)Retinenel + DPN4H + vitamin A + DPN(normally DPN, etc., is washed out of the rods when they are separated).The rhodopsins obtained from different species are not necessarilyidentical, the prosthetic group may well be the same in all cases but theprotein need not. There is in fact some evidence of species differences inthe precise position of Amax., e.g. 503 mp. for frog rhodopsin and 498 mp. forrat rhodopsin.57 The E,lTm.is of the order of 6.6 58 although this needsconfirmat ion.The conversion of rhodopsin into indicator yellow has been studied insome detail. The first clue to the nature of the pH-sensitive product wasthe preparation of compounds closely analogous to it by the interaction ofretinene and many amines and proteins. 59? 6oA typical experiment made use of a protein solution from sheep retinas.When retinene was added, Amax. was a t 387 mp., displaced to 365 mp. whenthe solution was made alkaline ; subsequent acidification resulted in ashife of h,,,. to 440 mp. Em,,. values at 387 and 440 mp. were practicallythe same.The change in intensity of absorption ( ~ E ~ O O ~ ~ . ) which occurs on com-plete bleaching of rhodopsin solution measures the photochemical destruc-tion, and the increase in absorption a t 370 mp. (hE37omP.) measures theformation of alka.line indicator yellow.AE370mp. fAE500mp. is found to be0.75 at pH 9.2, and a t pH 1-76 eE440mp./AE500mfi. = 0.37.61 Ereshly bleached,neutral solutions of rhodopsin contain not only the indicator-yellow systembut also some retinene. It appears that retinene is formed from indicatorWith aliphatic amines such as methylamine (but not dimethylamine)pure retinene forms pH-sensitive derivatives, having hmaX. 440 mp. in acidyellow.67 F. D. Collins and R. A. Morton, Biochem. J., 1950, in the press.58 E. E. Broda, C. F. Goodeve, and R. J. Lythgoe, J. Physiot., 1940, 98, 297.6s S. Ball, F. D. Collins, R. A. Morton, and A. L.Stubbs, Nature, 1948, 161, 424.61 F. D. Collins and R. A. Morton, ibid., 1950, in the press.S. Ball, F. D. Collins, P. D. Dalvi, and R. A. Morton, Bioehem. J., 1949, 45, 304264 BIOCHEMISTRY.and 365 mp. in alkali. Two molecules of retinene appear to react with oneof methylamine :. .(full conjugation restored, Amax. 440mp.)(I) corresponds to alkaline and (11) to acid indicator yellow. If thesemethylamine derivatives are true analogues of indicator yellow its structuremust be similar, with an amino-group of a protein replacing that ofmet hylamine.Detailed study of the spectra 62 has led to the following figures : 63cr = 39,000, E , = 40,00On, = 49,00On, and E , = 47,200m;where c7, E,, q,, and €6 are the maximal molecular extinction coefficientof retinenel, indicator yellow, rhodopsin, and alkaline indicator yellow,respectively, and p = the number of C,, (retinene or vitamin A) residuesin the rhodopsin chromophore, and n and rn the number of such residues inacid and alkaline indicator yellow, respectively.Both n and m probablyequal 2, hence E, = 80,000 and cb = 98,000.Transient Orange, This is conveniently prepared by cooling a thinlayer of rhodopsin solution to -70" and illuminating the solid from allsides.63 The freshly frozen solution is pink but it becomes orange onirradiation. At low temperatures transient orange is quite stable to light.After irradiation the material is allowed to reach room temperature incomplete darkness. The absorption spectrum is then determined and anapparent 50% regeneration of rhodopsin is recorded.The whole operationcan be repeated and there is then 25% regeneration expressed in terms ofthe original rhodopsin absorption. The formation of transient orange andregeneration can be observed several times until the E value a t ca. 500 mp.becomes very low. The maximum appears to be displaced some 8 mp. inthe direction of shorter wave-lengths after the first regeneration but remainsunchanged in subsequent regenerations. The regenerated product iscalled '' isorhodopsin " because it is not identical with rhodopsin. Theabsorption curves show that indicator yellow is formed in amounts corre-sponding with the rhodopsin which has disappeared. The quantitativedata are consistent with the following scheme := 49,3OOp,rhodopsin + nhv ---+ transient orangeisorhodopsin + nhv ___p transient orange*I F.D. Collins and R. A. Morton, Nature, 1949,164,528.2 transient orange --+ indicator yellow + isorhodopsin2 transient orange --+ etc.d8 Idem, ibid., in the pressMORTON : CAROTENOIDS, VITAMIN A, AND VISUAL PIGMENTS. 265Freezing to -70" stops the sequence at the transient orange stage andwarming to room temperature in the dark isolates the thermal change.If the rhodopsin chromophoric group is(with many resonance forms)transient orange will be a free radical :rhodopsin + nhv 4 transient orange +and dismutation will result in half the transient orange molecules losinganother electron and forming indicator yellow. Ordinary rhodopsin isassumed to consist of two chromophoric groups attached to the same proteinmolecule and manifesting some mutual interaction so that Amax.is shiftedslightly. After the absorption of light and the subsequent dismutationof transient orange, one chromophoric group will have been converted intoindicator yellow leaving one isolated isorhodopsin chromophoric group.Subsequent dismutation of transient orange will be intermolecular and willresult in the continued formation of isorhodopsin.If, as has been suggested, the emax. value for rhodopsin is 48,OOOp andp = 2 the molecular extinction coeft3cient will be 96,000. It has previouslybeen shown that E,,,. x y = 24,000, where y is the quantum effi~iency.~~Hence the overall value of y will be 0.25. As the dismutation of transientorange reduced the quantum yield by SO%, y for the primary process willbe 0.5.Given that Emax. is 96,000 and the intensity of absorption forrhodopsin is about E',&. = 6.6 the upper limit for the carrier weight isabout 145,000. This is roughly half the molecular weight of 270,000 observedby Hecht and Pickels in 1938 and it supports the idea of two prostheticgroups in rhodopsin itself.Wald has founds5 that the photochemistry of rhodopsin is possiblymore complicated than is suggested above, and the detailed account of hisresults is awaited with interest. The interpretation suggested by Collinsand Morton should be regarded as EL first attempt a t a consistent scheme,it may need modification in detail, but there is no real conflict with Wald'sresults.Cone Pigments. The attempts to isolate cone pigments have not beenvery successful and some of the published evidence is technically questionable,but sinte rhodopsin accounts for the scotopic luminosity curve it is natural64 E. E. Schneider, C. F. Goodeve, and R. J. Lythgoe, R o c . Roy. Soc., 1939, A ,170, 102.Lecture at First International Congress of Biochemistry, 1949266 BIOCHE&5XSTRY.to postulate the existence of iodopsin to account for the photopic luminositycurve. Wald,66 using the weakest red light in which he could work, obtainedan aqueous digitonin extract of chicken retinas and measured the absorptionspectrum before and after exposure to light of wave-length 650 mp. Thedifference spectrum with Amax. at 575 mp. was attributed to iodopsin. Bliss 67carried out similar experiments and found A,,,, a t 560 mp. The destructionof iodopsin resulted in the liberation of retinene.The photopic luminosity curve is a reality-the problem is whether itis due to a single pigment, iodopsin, or to a summation of three modulatorcurves. Difference curves throw no light on this and the occurrence ofretinene as a “ bleaching ” product would fit either view. Wright 68determined the luminosity curve with a small foveal patch of low brightnessand found Amax. 560 mp. with an inflexion near 600 mp. confirmedthis by a different approach on the cat-dominator curve. A good case canbe made out that the photopic dominator is a synthesis of three modulatorcurves-recalling in some ways the Young-Helmholtz trichromatic theory.The experimental evidence leads to the view that the status of “ iodopsin ”is rather doubtful.One striking fact, however, remains, namely that as the key substancefor cone vision as well as rod vision, no alternative to vitamin A has emerged,and the narrow modulator curves are a persistent challenge. As is well-known, vitamin A and the retinenes give rise to deeply coloured blue orblue-green solutions with antimony trichloride in chloroform. The sharp-ness of the absorption bands (coupled with the transient nature of the bluecolours) suggests that under suitable conditions vitamin A or retinene mightgive rise to ionized or halochromic molecules 70 resembling Granit’smodulators.I n fact when vitamin A or retinene is dissolved in concentrated sulphuricacid or syrupy phosphoric acid a t temperatures near 0” coloured solutionsare formed which exhibit well-defined selective absorption with maximacorresponding closely with those of Granit’s modulators : 71Absorption Maxima in Strongly Ionizing Media.GranitConc. H,SO,. Conc. H,P04.Vitamin A, ......... 465, 520-530, 590-620 mp. 440-480, 520, 620Vitamin A, .... .....Retinene . . . . . . . . .Re tinene, . . . . . . . . .540, 560, 590, 660, 680, (720)450, 525, 570, 664470, 525, 570590 persistent, (695, transient)470, 500, 550, 590, 664470, 505, 570, 600 (at first)470, 505*, 560, 590 (after 2 hrs.) * Enhanced on storage.Granit’s modulators 450-465, 500, 520-530, 580-610.O6 G. Wald, Nature, 1937, 140, 546.67 A. F. Bliss, J . Gen. Phyxiol., 1946, 29, 277, 299.W. D. Wright, Nature, 1943, 161,6@ R. Granit, Proc. Physical SOC., 1945, 57, 447.‘O P. Meunier and A. Vinet, ‘‘ Chromatographie et MbomBrie,” 1947, Masson71 8. Ball and R. A. Morton, Biochem. J., 1949, 45, 298.et lie, ParisMORTON : CAROTENOIDS, VITAMIN A, AND VISUAL PIGMENTS. 267Although the conditions are not physiological, the agreement indicatesthat vitamin A and the retinenes are sufficiently versatile to permit theappearance of substances spectroscopically analogous to the modulators.The outstanding problems are (a) to produce a rhodopsin-like pigmentfrom the indicator-yellow analogues and (b) to produce the modulatoranalogues under conditions similar to those obtaining in the retina. Therecan be little doubt, however, that the evidence being collected by variousgroups of workers will lead to a unified picture. This is due in no smallpart to the labours of physiologists which are inadequately reported here,During the period covered by the Report the subject of vision sustained a,great loss in the death of Selig Hecht, who had done much pioneer workof great and lasting value.72 R. A. M.W. F. J. CUTHBERTSON.C. RIMINGTON.R. A. MORTON.Described in an obituary notice by G. Wald, J . Gen. PhysioZ, 1949, 32, 1

ISSN:0365-6217    

DOI:10.1039/AR9494600229

出版商:RSC    

年代:1949

数据来源: RSC

摘要:

ANALYTICAL CHEMISTRY.1. INTRODUCTION.EAUH year the activities of the analytical chemist become more diversifiedand no fewer than 3600 papers are summarised in Section C of BritishAbstracts for 1949. Though the future considered policy of these Reportswill be to summarise progress of the current year, this volume follows thepattern of its predecessors in presenting accounts of certain discrete topics,viz., organic and gravimetric analysis and the analytical applications ofRaman spectra and of organic reagents, in order to bring up to date thereviews of some topics and to repair other omissions. The report on gasanalysis shows the extent to which physical methods have supplemented orsupplanted classical methods in the past decade, and the section on radio-activation analysis describes a new and powerful technique of great sensitivity.Attention should be drawn to a series of well-documented and illustratedreviews covering work of the past five yea.rs and intended as a basis for itprojected new series of annual reports.1 The 29 articles (totalling 170pages with 3700 references) deal with ultra-violet and visual spectrophoto-metry ; Raman and mass-spectrometry ; the absorption and diffractionof X-rays ; emission and infra-red spectroscopy ; electron and light micro-scopy ; polarogra.phy, amperometry , and electroanalysis ; inorganic (andorganic) microchemical, gravimetric, and volumetric analysis ; distillation,extraction, ion-exchange, indicators, nucleonics, instrumentation, fluori-metry, and statistics. H.M. N. H. I.2. GCRAVIMETRIC ANALYSIS.Balances.-Where rapid volumetric or physical methods of analysis areto be used, the time spent in weighing the sample may well comprise a.nuneconomically large fraction of the whole. Aperiodic balances haverecently been marketed in .which built-in weights operated by control knobsreplace all external and fractional weights, and direct-reading scales displaythe weight of the object which can easily be obtained within one minute.The remarkable balance designed by E. Mettler has only one pan and thesensitivity remains constant a t 0.05 mg. over the range 0-200 g.In adapting a standard analytical balance to work on the micro-scale,the familiar expedient of setting the sensitivity as high as possible and readingthe deflections of the freely swinging beam is provocative of eye-strainwhich can be minimised by a photo-electric attachment described by C.L.Rulf~.~ If the radiation from an a-active source attached to one beam ofa micro-balance is received in an adjacent 3-plate ionisation chamber, theAndyt. Ghem., 1949, $31, 1 to 173. * Cf. R. H. Muller, ibbid., 1948, 80, 29, A , IbM., p. 262IRVINa : GRAVIMETRIU ANALYSIS. 269displacement from a null position cttn be amplified electronically to give asensitivity of 1 pg. per mm. deflection of a spot-gal~anometer.~ By theaddition of twin photo-tubes and a d.c. amplifier J. W. Clarke has de-veloped the principle of the magnetic balance and produced a prototypedirect-reading null instrument which is faster to use and requires less skillthan its mechanical counterpart.Accounts have been published of micro-gram balances employing quartz torsion fibres or helices,? and B. B.Cunningham and L. B. Werner describe measurements of the specificactivity of plutonium which demanded the construction of a Salvioni-typebalance to give a sensitivity of 0.01 pg. with a load of 10 pg.Weights and Weighing.-A. Craig lo discountenances the use of leadin the inner cavity of weights and notes gradual increases in weight even afterlacquering : storage in silk or paper is preferred to a velvet-lined box whichmay promote corrosion.11 C. Herbo l2 points out the series of uselessoperations involved in classical procedures for calibrating sets of weightsby substitution or transposition and describes a simpler method.Althougha new explanation has been advanced l3 to explain the troublesome driftsometimes observed during the course of a weighing, no general agreementhas yet been reached on the desirability of drying non-hygroscopic substancesor on the use of desiccants in the balance chamber.Changes in the weight of a body under isothermal conditions can beused to follow quantitatively the progress of, e.g., corrosion,14 photo-decomposition, weathering, solvation and absorption. Such changes, andthose which result when a body is exposed to a steadily changing tem-perature, can conveniently be studied with recording thermo-ba1an~e.l~Duval and his associates have studied the pyrolysis curves of more than700 substances commonly obtained in gravimetric analysis, and haveestablished the temperature ranges over which the initial precipitates canbe brought to constant weight as a definite hydrate, an anhydrous salt, orsome one or other specific decomposition product.The original papers(Parts I1 to XXVIII) deal in order l6 with compounds of Ca, Sr, Ba, Mg,Be, Li, Na, NH,, K, Rb, Cs, T1, La, Ce, Ne, Sm, Sc, Pr, Eu, Al, Ga, In, U,4 I. Feuer, Analyt. Chem., 1948, 20, 1231. ti Rev. Sci. Instr., 1947, 18, 915.P. L. Kirk, R. Craig, J. E. Gullberg, and R. Q. Boyer, AnaZyt. Chem., 1947,19,P. L. Kirk and F. L. Schaffer, Rev. Sci. Imtr., 1948,19, 785.J . Amer. Chem. SOC., 1949, 71, 1521.427.* E. Salvioni, " Misura di mase comprese fra g. 10-1 a g.lo Analyt.Chem., 1947, 19, 72.l1 F. J. Maffei, Amis Amoc. Quim. B T ~ , 1946,5,53.l2 Analyt. Chim. Acta, 1947, 1, 254.l3 F. E. Beamish, Analyt. Chem., 1949, 21, 144.l4 P. Chevanard, X. Wache, and R. de La Tullaye, BUZZ. SOC. chim., 1944,11, 41.l 6 Y. Jouin, Chim. et Ind., 1947,!58,24; C . Duval, AnalyL Chim. Acta, 1947,1, 341,l6 C. Duval and S . Peltier, ibid., pp. 345, 355, 360; C. Duval and T. DuvaI, &id.,1948, 2, 45, 53, 57, 97, 103, 105, 110, 205; C. D u d and S. Peltier, <bid., pp. 218, 222,226, 228; 1949,3, 183, 186, 189,191; C. Duval and T. Dupuis, ibid., pp. 324,330,335,345, 438, 589, 599.Me8sin8, 1907270 ANALYTICAL CHEMISTBY.Cr, Gd, Th and Mn, and should be consulted for details of the work, which isof fundamental importance for gravimetric practice.The automaticthermo-gravimetric analysis of mixtures (e.g., Ca and Mg precipitated asoxalates, or Cu and Ag in an alloy) can often be carried out once the behaviourof the pure components has been established.17 It has also been shownthat " ashless " filter-papers lose their absorbed water below 75" and keepconstant weight up to 180" : ashing is completed a t 675".lS The weightof Gooch asbestos, dried by 75", remains constant up to 283" only and thendecreases grad~al1y.l~Gravimetric Procedures.-In addition to work with organic reagentsnoted below (p, 271), much attention has been paid, particularly among thealkaline and rare earths and their congeners, to problems of separation andthe techniques of obtaining precipitates in forms suitable for fi1trati0n.l~Tore Holth 2o has studied critically the use of ammonium oxalate in theseparation of calcium from magnesium, though with high Mg : Ca ratios apreliminary separation of most of the magnesium as hydroxide may bedesirable.21 A dense, coarsely crystalline precipitate of magnesium oxalatewhich can be readily filtered and washed is achieved by slowly generatingoxalate ions in situ by the hydrolysis of ethyl oxalate in 85% acetic acidsolution.22 The same process of '' precipitation from a homogeneoussolution " has been applied successfully to the precipitation of ZrO(H,PO,),by means of alkyl phosphates or pyroph0sphates,2~ to the precipitation ofthorium and rare-earth oxalates from monazite by means of methyl oxalateF4and the isolation of thorium from admixture with rare earths by use oftetrachlorophthalic Radioactive pyrophosphate has been used inone method for determining thorium,26 and sodium paraperiodate 27 andm-nitrobenzoic acid have also been examined as precipitants.Radio-active ruthenium being used, an interesting study has been made of itsfire-a.ssay29 which showed that loss of the volatile tetroxide during fusionand cupellation was negligible although the slag and cupel retained significantamounts-bservations which may well have a bearing on the refining ofthe other precious metals. H. M. N. H. I.l7 C. Duval, Analyt. Chim. Acta, 1948,2,432.l8 Idem, ibid., p. 92.*O Andyt. Chem., 1949, 21, 1221; cf. E. R. Wright and R. H.Delaune, Ind. Eng.21 J. A. Greear and E. R. Wright, Analyt. Chem., 1949, 21, 696.za L. Gordon and E. R. Caley, ibid., 1948, 20, 560.23 H. H. Willard and R. B. Hahn, ibid., 1949,21, 293; R. B. Hahn, Microfilm Abstr.,24 H. H. Willard and L. Gordon, Analyt. Chm., 1948, 20, 166.26 L. Gordon, C. H. Vanselow, and H. H. Willard, ibid., 1949, 21, 1323.2e T. Moeller and G. K. Schweitzer, dbid., 1948, 20, 1201.27 M. Venkataramaniah and B. S. V. R. Rao, Cum. S&., 1949,18, 170.9-8 G. H. Osborn, Analyst, 1948, 73, 381.2s R. Thiers, W. Graydon, and F. E. Beamish, AnaZyt. Chenz., 1948,20, 831.Idem, ibid., 1949, 3, 163.Chem. Anal., 1946, 10, 426.1948, 8, No. 1, 25IRVING : ORGANIU REAGENTS IN INORGANIC ANALYSIS. 27 13. ORGANIC REAGENTS IN INORGANIC ANALYSIS.Introduction.-Many extensive studies of groups of related organiccompounds have lately been made in attempts to correlate structure andgroup-reactivity or to procure reagents of greater sensitivity or selectivity,and the recent literature of the subject 3O has been enriched by a notablecontribution from F.Feigl.31The important observation 32 that 2-methyloxine (8-hydroxyquinaldine)differs from oxine in giving no precipitate with aluminium has been confirmedby H. Irving, E. J. Butler, and M. 3’. RingF3 who show that this peculiarity(due in part to steric factors) is shared by 2 : 4-dimethyl- and l-phenyl-8-hydroxyquinoline, l-hydroxyacridine, and 9-hydroxy-1 : 2 : 3 : 4-tetrahydro-acridine, though 5-, 6- and 7-methyl-8-hydroxyquinolines react normallywith aluminium and all these reagents give insoluble complexes with Zn,Cu, Ga, CrIII and FeIII.Mercaptobenzthiazole has been recommended asa precipitant for rhodium,3* and a-furil d i ~ x i m e , ~ ~ n i ~ x i m e , ~ ~ and 1 : 10-phen-anthroline 37 are excellent for palladium. Organic reagents for uranium 38include isatin p - ~ x i m e , ~ ~ and the potentialities of isatin a-oxime 40 andisatin P-semicarbazone and its N-methyl and -benzyl derivatives 41 andisoquinoline 42 have also been explored. Dicyanodiamidine has been used 43to precipitate vanadium as C,H,ON,,HVO, and o-dianisidine forms insolublecompounds with molybdates44 and with copper in the presence ofammonium thiocyanate : 45 in each case there are many interferencesand the precipitates must be ignited to oxide before weighing.Phyticacid (inositol hexaphosphoric acid) precipitates scandium quantitatively 46*O J. F. Flagg, ‘‘ Organic Reagents Used in Gravimetric and Volumetric Analysis,”N. York, Interscience, 1948; F. J. Welcher, “ Organic Analytical Reagents,” Vols. I-IV, N. York, D. van Nostrand Co., 1947-48; J. H. Yoe in “Recent Advances inAnalytical Chemistry,” Interscience, N. York, 1949, pp. 31, 49; P. Wenger and R.Duckert, “ Tables of Reagents for Inorganic Analysis,” Third Report, of the Inter-national Committee on New Analytical Reagents and Reactions, Bade, Wepf & Co.,1948.81 “The Chemistry of Specific, Selective and Sensitive Reactions,” N. York,Academic3 Press, 1949.32 L. L. Merritt and I.K. Walker, In&. Eng. Chem. And., 1944, 16, 387.s3 J., 1949, 1489.34 D. E. Ryan and P. Fainer, Canadian J . Em., 1949, 27, B, 72; cf. Uazzetta, 1948,36 S. A. Reed and C. V. Banks, Proc. Iowa Awd. Sci., 1948, 55, 267.3 6 R. C. Voter, C . V. Banks, and H. Diehl, Analyt. Chem., 1948, 20, 458.38 E. Ware, U.S. Atomic Energy Comrn., Aug. 1946, Rep. MDDC--1432, 20 pp.3* V. Hovorka and Z. Holzbecher, CoU. Trav. chim. Tc%cosl., 1949,14,40.40 V. Hovorka and L. Divis, ibid., p. 116.41 V. Hovorka and Z. Holzbecher, ibid., pp. 186, 248.42 A. E. Spakowski and H. Freiser, Analyyt. Chem., 1949, 21, 986.43 J. Fidler, Coll. Trav. chim. Tche’cosl., 1949, 14, 28.44 F. B. Ubeda and E. L. GonzaIBz, Anal. 2%. QuCm., 1944, 40, 1312.45 F. Buscarons and E.Loriente, ibid., 1948, 44, 215.46 G. Beck, Mikrochern. mikrochim. Acta, 1948, 34, 62.78, 293.D. E. Ryan and P. Fainer, Canadian J . Rm., 1949, 27, B, 67272 ANALYTICAL CHEMZSTRY.as Sc6C6H6P6O2, ,36H20, and after oxidation thallium can be determinedgravimetrically as [ (C,H,),AS]+[TICI,]-.~~Dimethylglyoxime is only sparingly soluble in water at room temperatureand is commonly used in ethyl alcohol or acetone solution. Their solventaction on the red nickel complex, and the danger of contamination by excessof precipitant, can be minimised by using solutions of the sodium or am-monium salt of the reagent-but these do not keep well. Though moresensitive and 17 times more water-soluble than dimethylglyoxime, “ nioxime ”(cyclohexane-1 : 2-dione dioxime) precipitates nickel down to pH 3 butpermits no separation from iron and the complex is not easily filtered.36CycbPentanedione dioxime is still more soluble but it precipitates nickelonly over a restricted pH range.However, ‘‘ heptoxime ” (cycloheptane-1 : 2-dione dioxime) precipitates nickel quantitatively at pH 2.7 and above+*and although it is only 9 times as soluble as dimethylglyoxime it has out-standing advantages. cc-Furil dioxime should not be used in nickel deter-minations, 8s the composition of the precipitate varies with and whilstthe relatively cheap ‘‘ niccolox ” (diaminoglyoxime) gives a stoicheiometricyellow complex which does not creep and is stable to dryingt9 iron andcobalt interfere seriously. The use of wetting agents to reduce the creepingof nickel-glyoxime precipitates has been thoroughly studied by J.N.Ospenson.50 Electron microscopy 51 shows that cobalt and iron separatelyaffect the appearance of crystals of nickel-dimethylglyoxime (withoutaffecting the weight), and confirms the formation of amorphousC O F ~ C ~ , H ~ , ~ ~ ~ , when both are present.Indicator~.5~-The extensive series of papers by G. F. Smith and hiscollaborators dealing with the synthesis of polysubstituted phenanthrolinesand 2 : 2’-dipyridyls, the absorption spectra of their ferrous and ferriccomplexes, and their applications as redox indicators has recently beensummarised.53 I. M. Kolthoff has studied the kinetics of formation anddecomposition of the ferroins (and ferrins), Le., the ferrous (and ferric)trisphenthroline complexes.% The redox potentials of the ferroins varypredictably and additively with the number and extent of sub~tituents.~~Methyl groups in positions 3 (or 8), 5 (or 6) and 4 (or 7) lower i t by 0.03,0.04 and 0.11 volt, respectively, so the whole range from 1.10 to 0.84 canbe covered smoothly.5 : 6-Dimethyl ferroin (redox potential 0.97 v. inIN-acid), recommended as the best indicator for ferrous-dichromatetitrations,55 may soon be replaced by 4 : 5 : 7-trimethylferroin which has a47 W. T. Smith, AmZyt. Chem., 1948, 20, 937.4s R. G. Voter and C. V. Banks, ibid., 1949, 21, 1320.O9 M. Kuras, Coll. Czech. Chem. Comm., 1947, 12, 198; Mikrochem. mikrochim.rjo Acta Chem. Scand., 1949, 3, 630.61 R.B. Fisher and S. H. Simonsen, Anal@ Chem., 1948, a0, 1107.62 Cf. I. M. Kolthoff, ibid., 1949, 21, 101.63 W. W. Brandt and G. F. Smith, {bid., p. 1313.65 G. F. Smith and W. H. Brandt, Anulgt. Chm., 1949,21, 948.Acta, 1944, 32, 192.fbid., 1948, 20,985; J . Amer. Chem Soc., 1948,70, 2348IRVING : ORGANIU REAGENTS IN INORGAXIC ANALYSIS. 273still lower redox potential of 0.84 v. and the largest molecular extinctioncoeficient of all the ferroins .53 Nickel-dimethylglpxime has been proposedas an external indicator for the same titration and can also be used inacidimetry and in the determination of nickel with cyanide.56 The valueof a-naphthaflavone as a reversible indicator for bromate titrations hasbeen ~onfirmed.~’ M. Taras 58 proposes disodium 4 : 4‘-di-2”-amino-l’’-naphthylazostilbene-2 : 2’-disulphonate and two analogues to replacemethyl-orange or -yellow, €or which artificial colour standards have beendevised by M.L. Nichols and B. L. I r ~ g r a m . ~ ~ 7-Acetamido-2-methyl-quinoline-5-carboxylic a.cid is recommended as a fluorescent indicator,mchanging sharply between pH 7.6 and 8, and Congo-red,61 bromothymol-blue and bromocresol-purple,62 and bromophenol-blue 63 have been usedas adsorption indicators for AgC with CI‘, Agf with CNS‘, and Tl+ with If,respectively. N-Methyldiphenylamine-red can be used for Ag+ with C1’or Br‘ even in strongly acid solutions.64 M. M. Davis, P. J. Schuhmann,and M. E. Lovelace 65 have extended earlier studies of bromophthalein-magenta as an indicator for titrations in benzene to a number of othersulphonphthaleins.Complexing Agents and ‘‘ Complexones.”-Interfering ions can often be“ masked ” by transformation into stable complexes with anions such asF’, Pod3-, CN’, and CNS‘, but though many photometric determinationsand extractive separations depend upon the formation of stable complexesbetween metals and organic reagents, their use as specific masking agentsis still open to development. Tartaric, citric, and other hydroxy-acidshave long been used to ‘‘ hold up ” Cu, Al, Cr, FeIII, etc., sulphosalicylicacid 66 will sequester Be, Ni, and U0,2+, and permits the separation of Mn,TI, or Ti from Fe.Thioglycollic acid masks Fe3+ in the photometric deter-mination of A1 with alumin0n,~7 and in the determination of low concen-trations of aluminium in iron ores 2 : 2’-dipyridyl, by complexing Fe2+,prevents coprecipitation of Fe(OH), with AI(OH),FR = H) and itsderivatives (11 to V), whose properties, first noted in the patent literatureof 1935,69 were thoroughly examined by Schwarzenbach 70-77 who aptlyEspecially noteworthy are iminodiacetic acid (I;56 F. Burriel and F.Pino, Anal. Pis. Qulm., 1949, 45, B, 43.67 R. Belcher, Analyt. Chim. Actu, 1949, 3, 578.5 8 Analyt. Chem., 1948, 20, 680; J . Amer. Water Works A ~ ~ o c . , 1948,40, 468.6* Analyt. Chem., 1948, 20, 1188.6o L. Velluz and M. Pesez, Bull. SOC. chim., 1948,15, 682.61 R. C. Mehrota, J . Indian Chem. Soc., 1948, 25, 541.Idem, Analyt. Chim. Acta, 1949, 3, 69.H. Schlifer, 2.anal. Chem., 1949, 129, 222.65 J . Res. Nat. Bur. Stand., 1947, 39, 221; 1948, 41, 27.66 G. Mannelli, Ann. Chim. appl., 1948, 38, 594.6 7 E. M. Chenery, Analyst, 1948, 73, 501.68 G. F. Smith and F. W. Cagle, Analyt. Chem., 1948, 20, 574.6s Fr. P. 47875, 811938, 822688, 845587.‘O G. Schwarzenbach, E. Kampitsch, and R. Steiner, Helv. Chim. Acta, 1945, 28,63 Idem, ibid., p. 73.828, 1133; 1946,29, 364274 ANALYTICAL CHEMISTRY.termed them " complexones ". Although the stability of most metalcomplexes diminishes rapidly (along a horizontal period) with decrease inthe atomic number of the central atom 78 and falls below that ofthe corresponding aquo-complexes in the case of the alkaline earths andalkali metals, yet chelate-ring formation always enhances stability, and thepolydentate nature of the complexones is such that they can form verystable wa,ter-soluble complexes with magnesium and the alkaline-earthmetals and some even complex significantly with lithium and sodium.Among them the capacity to mask calcium and magnesium (which is ofobvious technical importance in, 'e.g., the removal of lime soaps and dressingfrom textiles, in washing powders, and in photographic developing baths)was found to be especially high in nitrilotriacetic acid 7O (11; the disodiumsalt is marketed as '' Trilon A "), ethylenediaminetetra-acetic acid 72 (I11 ;n = 2 ; the active principle of " Ergalon T " ; the disodium dihydrogensalt dihydrate is " Trilon B "), uramildiacetic acid (IV),73 and exceptionallyso in 1 : 2-diaminocyclohexanetetra-acetic acid (V).', The stability of(IV. 1complexesstill morerare earthNA2*[CH2],*NA,(111.)R*NA2 NA3(1.1 (11.1NH-CO /?p 3 2 p3-NA2 60 \ )CH*NA, CH, CH*NA2NH-CO \ / (V.1(A=CHz*C02H) CH2with the transition metals and with tervalent kations is naturallymarked: a pH of 13 can be reached without precipitation ofhydroxides if (11) or (111) is present.79 That bi- and ter-valentkations can displace hydrogen ions from complexes has been made the basisof a number of volumetric determination^,^^^ 753 76 viz.: ( A ) On addition ofkations to at solution of, e.g., Trilon B, the pH falls from 5 to 3 in consequenceof the reactionMpp+ + H,Y2- --j MYn-* + 2H+and the acid formed can be titrated by using a potentiometric or visual71 G.Schwarzenbach, A. Willi, and R. 0. Bach, HeZv. Chim. Acta, 1947,30, 1303; G.Schwarzenbach, H. Ackermann, and P. Ruckstuhl, ibid., 1949, 32, 1175.72 G. Schwarzenbach and H. Ackermann, ibid., 1947, 30, 1799; 1948, 31, 1029;1949, 32, 1543, 1682.73 G. Schwarzenbach and W. Biedermann, ibid., 1948, 31, 457.74 G. Schwarzenbach, W. Biedermann, and F. Bangerter, ibid., 1946, 29, 811.75 G. Schwarzenbach and W. Biedermann, ibid., 1948,31, 331, 459.7 6 Idem, Chimia, 1948, 2, 56; Helv. Chim. Actu, 1948, 31, 678; G. Schwarzenbach77 G. Schwarzenbach, Chimia, 1949, 3, 1; HeZv. Chim. Actu, 1949, 32, 839; G.78 H. Irving and R. J. P. Williams, Nature, 1948,162, 746.79 H. A. Laitenen and E. Blodgett, J . Amer. Chem.Xoc., 1949, 71,2261.and H. Gysling, ibid., 1949, 32, 1314, 1484.Schwarzenbach and A. Willi, ibid., 1949, 32, 1046IRVING : ORGANIC REAGENTS IN INORGANIC ANALYSIS. 275indicator end-point.K3X or K,Y, the complexing reactions(B) On titration with fully neutralised complexones,M?$+ + X3- -> MXpZp3, or Mn+ + Y4- +cause no change in hydrion concentration, but a jump in pH from 5 to 9marks the appearance of excess of reagent, which is hydrolysed to giveHX2- (or H,Y2-) and hydroxyf ions. The course of a compleximetrictitration can often be followed by employing an indicator sensitive to theconcentration of the metal ions themselves. For instance, murexide(ammonium purpureate) serves as a selective metal-indicator 76 for Cu,for S C , ~ ~ and for Ca, thus permitting the determination of calcium-hardnessin water 74 since the indicator does not respond to Mg : total Mg + Cahardness can be obtained volumetrically by procedure (A) by using thetrialkali salt of Trilon B.Thiocyanate, thiosalicylate, or thioglycollateions serve as indicators for Co and Fe3+, and Eriochromschwarz T permitsthe direct compleximetric titration of Ca, Sr, Mg, Zn, and Cd and by aslight modification Pb, Mn, and Hg.76Complexones can stabilise higher valency states of some metals andmodify normal redox potentials. Since the redox potential of +1*S forCO~+/CO~+ is reduced to 0-6 volt (depending on the pH) by complexing withethylenediaminetetra-acetic acid (as 111), quantitative oxidation by cericions provides a new volumetric method for that element,s1 thoughmanganese and nickel interfere.Bismuthate or lead dioxide oxidisescolourless Mn(I1) to ruby-red Mn(II1) complexonate which can be reducedby standard ferrous or ferrocyanide ; no indicator is needed. SimilarlyCo( 111) complexonates [prepared by oxidation of Co(I1) complexonate a t60°, under which conditions the tervalent manganese complexes are un-stable] can be reduced quantitatively with chromous or titanous solutions.82Essentially the same procedure permits the determination of cobalt polaro-graphically in the presence of large amounts of nickel (or manganese) in abase solution containing Trilon B, for after preliminary oxidation the reduc-tion of the Co(II1) to Co(I1) complexonate gives a good wave with E,-O-1volt : in these circumstances complexonates of A1 or bivalent Co, Ni, andMn are not reduced.s3 Tervalent Cr, Co, Fe, Ti, and Mn give intenselycoloured red, violet, or blue complexes with Trilon B which should servefor their photometric determination.82 Although their efficacy in difficultseparations is demonstrated by their successful application to the classicalproblem of rare-earth fracti~nation,~~ the full potentialities of complexonesas masking agents in microchemical spot-tests and in gravimetric analysishave yet to be developed.s2G.Beck, Analyt. Chim. Acta, 1947, 1, 69.81 R. PZibil and V. MaliEk, Coll. Trav. chim. Tchkcosl., 1949, 14, 413.s2 R. PZbil, ibid., p. 320.83 P. Souchay and T. Faucherre, AnaZyt. Chim. Acta, 1949,3, 252.84 G.Beck and A. Gasser, ibid., p. 41 ; cf. G. Beck, Helv. C h h . Acta, 1946, 29, 357216 ABNALYTICAL UBEMISTRY.The applications of organic reagents to spot-tests, extractive separations,and absorptiometric determinations will be reported on next year..H. M. N. H. I.4. ANALYTICAL APPLICATIONS OF THE RAMAN EFFECT.The general nature of the Raman effect and its chemical applicationswere considered in the Annual Reports for 1934,l and in 1938 a short sectionwas devoted to uses in analytical chemistry. The object of the presentReport is to give a brief account of subsequent developments in the fieldof analysis, illustrated by selected examples. Early in 1949 a more extensivereview appeared which may be consulted for further references.When monochromatic light is passed through a pure transparentsubstance, the spectrum of the small fraction which is scattered contains,in addition to the Rayleigh line, a number of feeble lines of modifiedfrequency-the Raman spectrum.The frequency shifts, relative to theexciting line, are equal to normal vibrational frequencies of the scatteringmolecules and so are characteristic of the substance concerned. In mixtures,the Raman spectra of the components are superposed; but since the spectrausually consist of a relatively small number of more or less sharp lines,they remain distinct (except for fortuitous coincidences). It is upon thisthat the usefulness of the Raman effect for qualitative analysis depends.Since the intensity of Raman scattering is dependent on the concentrationof the molecules concerned, the effect can also be used for quantitativeanalysis.The method is to be regarded as complementary to those based uponultra-violet or infra-red absorption. It is especially useful for componentspresent in relatively large proportion.Although in special cases lowerconcentrations may be detected, the limit is generally about 1%. Forquantitative determinations the minimum may be set at about ‘5% forstrongly scattering species and 10 yo or more for components with intrinsicallyweak Raman spectra.When intermolecular forces between the components of a mixture aresmall, the qualitative and quantitative analysis may be carried out bycomparison with the spectra of the pure components. Such is generallythe case for mixtures of hydrocarbons, t o the analysis of which the Ramaneffect has been mainly applied.When intermolecular forces are stronger,the Raman spectrum of a mixture may differ considerably from a simplesuperposition of the spectra of the components. Such differences havebeen related to intermofecular-compound formation * and ass~ciation.~Ann. Reports, 1934,31, 21. Ibid., 1938, 35, 394.F. J. Taboury and R. Thomassin, C m p t . rend., 1946, 223, 627.* W. G. Braun and M. R. Fenske, AnaZyt. Chem., 1949, 21, 12.li L. Briill, J. Errera, and H. Sack, Rec. T T ~ v . chim., 1940, 59, 284; P. Kohwaram,I d k n J . Physics, 1940,14, 353 ; C. S. Venkateswaran and N. S. Pandya, PTOC. IndianAcad. Xci., 1942, 15, A, 401WOODWARD : ANALYTIOAL APPLICATIONS OF 'PHE m EFFLUT.27'7The exciting light being chosen so as to produce no photochemicaleffects, the determination of Raman spectra leaves the scattering systementirely unaffected and so may with advantage be used for the detectionand estimation of species in equilibria which cannot be " frozen." ThusM.-L. Delwaulle and F. Frangois 6 have detected the ion SnC1,' in solutionsof SnCl, containing excess of chloride ion : and similarly the ion SnBr,'.The same workers have used the Raman effect * to investigate the equilibriumHgX, + HgY, 2HgXY in solution, X and Y being C1, Br, I, or CN;and have demonstrated that mixed halides are formed on mixing stannicbromide with stannic chloride: or titanium tetrabromide with titaniumtetrachloride.1° They find,ll however, that the Raman spectrum of amixture of the tetrabromide and tetrachloride of silicon is a simple super-position of the spectra of the pure components, so that no mixed halideformation occurs in this case.Evidence has been obtainedI2 for thepresence of the species PFClBr in a mixture of PFCI, andPFBr,. Anotherapplication of a similar kind is to the ionization equilibrium of '' strong "acids in aqueous solution. 0. Redlich and J. Bigeleisen l3 have deter-mined the nitrate-ion concentration in solutions of nitric acid by comparisonof the intensity of its Raman spectrum with that in solutions of sodiumnitrate. Similar measurements have also been made l4 for perchloricacid.Excitation of Spectra.-The Raman effect is relatively feeble andintense irradiation of the sample is required.Recently A. C. Menzies andJ. Skinner l5 have described an efficient arrangement in which the sampletube and mercury arc lamps are surrounded by a water-cooled enclosurecoated internally with magnesium oxide, which has a very high reflectioncoefficient in the visible region. The 4358 A. line of mercury is generallyused as exciting line, but when obtained from ordinary high-pressuremercury arc lamps it is accompanied by a, continuous background whichtends to obscure weak Raman lines and renders quantitative photometrymore difficult. The intensity of this background may be diminished byunder-running normal lamps l5 or by the use of low-pressure arcs withcooled mercury electrodes.16 Filters may also be used, both t o reduce thebackground and also to isolate appropriate mercury lines.Useful trans-mission data for filter solutions are given by R. F. Stamm.17 Solid filtershave also been used.18 Objectionable fluorescence of the sample may beCompt. rend., 1940, 211, 65.BuEE. Xoc. chim., 1940, 7 , 359.Ibid., 1941, 212, 761.Compt. rend., 1944, 219, 64.lIL Ibid., 1944, 219, 336. lo Bid., 1945, 220, 173.la M.-L. Delwaulle and F. Franqois, ibid., 1946, 223, 796,l8 J . Amer. Chem. Soc., 1943, 65, 1883.l4 0. Redlich, E. K. Holt, and J. Bigeleisen, ibid., 1944, 66, 13.l5 J . Sci. Instr., 1949, 26, 299.l6 D. H. Rank and J. S. McCartney, J . Opt. Soc. Amer., 1948, 38, 279.l7 Id. Emg. Chem. Anal., 1945,17, 318.B.L. Crawford and W. Horwitz, J . Chem. PhysiCe, 1947, 15, 268; Q. Glocklerand J. F. Haskin, ibid., p. 759278 ANALYTICAL CHEMISTRY.removed by adsorbents 19v20 or by the addition of quenchers.21 The lastwork referred to gives a review of analytical applications of the Ramaneffect up to 1939. Owing to the extreme feebleness of the effect for gases,all the applications have been to the liquid phase.Photo~aphic Method.-Until recently (see below) photography wasthe only method of obtaining Raman spectra, and all the work so farreferred to in this Report was done photographically.Apparatzm-Owing to the relatively low intensity of the effect, a luminousspectrograph with a fast camera is desirable. Rank, Scott, and Fenske l9describe a 3-prism instrument with an f 4-5 camera, and an account of agrating instrument with an f 3.6 camera is given by Stamm.17 The volumeof sample is usually in the neighbourhood of 10 ml., and with efficientexcitation exposure times of the order of minutes (or even less 15) may beused.Qualitative Analysis.---Applications to mixtures (predominantly organic)have been numerous, and some typical examples must suffice.Rank,Scott, and Fenske,lg Stamrn,17 and A. V. Grosse, E. J. Rosenbaum, andH. F. Jacobsonz2 have investigated the applicability of the method tohydrocarbon mixtures ; and motor spirits, both natural z3 and synthetic,2*have been analysed by means of the Raman effect. The method has beenfound useful for the analysis of the products of various organic reactionsand in the field of natural products.25Quantitative Analysis.-Whereas €or qualitative work it suffices toobserve the positions of the Raman lines, for quantitative analysis it isnecessary to undertake the more difficult measurement of intensities.Forthis purpose the photographic plate is notoriously a somewhat inconvenientand inexact agent. In addition, the dependence of the intensity of aselected Raman line of a component upon its concentration must be known.For mixtures in which intermolecular forces are not large the dependence isa linear one, and comparison with the intensity for the pure componentis all that is required. Such simple linear dependence has been verifiedfor hydrocarbon mixtures by various workers.26 Where there is reason todoubt linearityZ7 it becomes necessary to use as standards a number ofIs D.H. Rank, R. W. Scott, and M. R. Fenske, Ind. Eng. Chem. Anal., 1942,14,816.2O M. R. Fenske, W. G. Braun, R. V. Wiegand, D. Quiggle, R. H. McCormick, andD. H. Rank, Analyt. Chenz., 1947, 19, 700.2 1 See J. Goubeau in " Physikalische Methoden der malytischen Chemie " by W.Bottger, Leipzig, Akdemische Verlagsgesellschaft, 1939.22 Id. Eng. Chem. A d . , 1940,12, 191.23 See, e.g., J. Goubeau and V. von Schneider, Angew. Chem., 1940, 53, 531 ; S.Midzushima and T. Tobiyama, J. Chem. Soc. Japan, 1944, 65, 374; S. Midzushima,T. Tobiyama, and H. Shirakawa, $bid., p. 549.24 M.-L. Delwaulle, F. Franqois, and J. Weimann, Chim. et Id., 1946, 56, 292.25 For literature references see ref.(3).26 See refs. (17) and (19) ; also H. Gerding and A. P. van der Vet, Reo. Tmv. chim.,87 P. Traynard, Bull. Xoc. chim., 1945, 12, 981.1945, 64, 257WOODWARD : ANALYTICAL APPLICATIONS OF "FIE RAMAN EFFECT. 279mixtures made up with known proportions. Various schemes for deter-mining concentrations from measured intensities by the use of standardshave been considered by Stamm 17 and by Goubeau.21 Intensity com-parisons between unknown and standards may be facilitated by the additionof a known amount of a reference substance such as carbon tetrachloride l9or carbon disulphide.l7 Compositions of major components of hydro-carbon mixtures containing up to four compounds have been determined 28within about &2%, and the method has been successfully applied l7 to thequantitative analysis of solutions containing sodium nitrate and nitrite.For rough purposes, mere visual estimate by a practised observer 22 gavepercentages within about &lo.A method based upon line widths insteadof intensities has also beenPhotoelectric Method.-Owing to the characteristics of the photo-graphic plate, intensity determinations from microphotometer traces requirefor each plate and wave-length the use of a calibration curve obtained fromstandard intensity marks. Due correction has also to be made for con-tinuous background. The procedure is lengthy and the accuracy attainableis not high. It was therefore a notable advance when in 1942 D. H. Rank,R. J. Pfister, and P.D. Coleman first showed30 that Raman spectra couldbe recorded by using, in place of a photographic plate, an exit slit and aphotomultiplier cell as detector. In 1946 D. H. Rank and R. V. Wiegand 31gave a. full description of a grating spectrograph and photoelectric recordingapparatus suitable for use in quantitative analysis by means of the Ramaneffect. The spectrum is scanned by rotation of the grating and correspond-ing motion of the exit slit and photocell assembly; the photo-current isamplified by a d.c. unit and operates a galvanometer, whose deflectionsare recorded photographically. The intensity scale of the record is linear.A practical difficulty arises from the random " noise " of the photocell,which tends to give a fluctuating background to the record and must beminimised by cooling the cell with solid carbon dioxide.Similar arrange-ments, but using prism spectrographs, have subsequently been describedby J. Chien and P. Bender 32 and by P.-0. Kinell and P. T r a ~ n a r d . ~ ~ Morerecently, C. H. Miller, D. A. Long, L. A. Woodward, and H. W. Thompson34have given a description of a photoelectric instrument in which advantageis taken of the fact that, with mercury lamps run off the 50 c./sec. ax.mains, the exciting light (and hence also the Raman scattering) pulsatesa t 100 c./sec. The photo-current is amplified by a band-pass a.c. unit andrectified by a homodyne system. This has the advantage that the Ramansignal is preferentially amplified as compared with the random " noise,"28 See refs.(17) and (19); also J. Goubeau and L. Thaler, Angew. Chem., 1941, 54,26; 2. Elektrochem., 1941, 47, 150; E. J. Rosenbaum, C. C. Martin, and J. L. Lauer,Ind. Eng. Chem. Anal., 1946, 18, 731.2s G. Duyckaerts and G. Michel, Analyt. Chim. Acta, 1948, 2, 750.30 J . Opt. SOC. Amer., 1942, 32, 390.31 Ibid., 1946, 36, 325.a8 Acta. Chem. Smnd., 1948, 2, 193.34 Proc. Physical SOC., 1949, 82, A , 401.32 J . Chem. Physics, 1947,15,376280 ANaLYTICAL CEEMISTRY.which is thus largely eliminated from the record without the necessity forcooling the photocell. A commercial recorder of the pen type is used.The advent of photoelectric recording in place of photography enablesreliable intensity measurements to be made with greater speed, and opensup new possibilities in the application of the Raman effect to quantitativeanalysis. It is understood that complete photoelectric instruments willsoon be available commercially in this country as well as in America!.In their 1946 paper 31 Rank and Wiegand gave results for 18 syntheticmixtures (2-5 components) of aromatic hydrocarbons containing up to10 carbon atoms.These were all successfully analysed qualitatively andthe percentage compositions determined to within approximately &2. Theinstrument was used by M. R. Fenske et aE.,2* who give reproductions of theRaman spectra records of 172 pure hydrocarbons and also the so-called'' scattering coefficients '' of the lines, i.e., the intensities (as measured byrecorded deflections) relative to that of the Av = 459 cm.-l line of carbontetrachloride determined under the same conditions. These scatteringcoefficients are used in the quantitative analysis of synthetic hydrocarbonmixtures containing up to 6 components, linear dependence of intensityupon concentration being assumed.The determined percentages areusually within &2. Unfortunately, owing to the fact that, as in otherspectrographic methods of analysis, relative intensity measurements in theRaman effect depend on the nature of the instrument used, the scatteringcoefficients of Fenske et aE. (so useful in connection with the particularinstrument with which they were determined) cannot be used for quantitativeanalytical purposes with other spectrographs. Each worker should employstandards measured with his own instrument.The reasons for the variationof scattering coefficients from instrument to instrument have been con-sidered by Rank,35 who gives a method of correcting for one of them (dueto the different polarisation of Raman lines). Application of this correctionwould allow the use of the published scattering coefficients for roughquantitative analysis with any spectrograph. L. A. W.6. ANALYSIS OF ORGANIC COMPOUNDS.Determination of Carbon and Hydrogen.--During the past five yearsvery few drastic modifications of standard methods of combustion analysishave been proposed, and though the trend towards micro-analysis continues,American analysts 1t have stressed the greater reliability of the macro-method, particularly for discriminating between substances which differin their carbon and hydrogen contents by only a fraction of a per cent.Automatic combustion units, several of which have been described: are,55 Analyt.Chem., 1947,19, 766.D. D. Wagman and F. D. Rossini, J. Res. Nat. Bur. Stand., 1944,32,95.D. D. TunniclB, E. D. Peters, L. Lykken, and F. D. Tuemmler, Id. Eng. Chem.* R. 0. Clark and C. H. Stillson, AnuZyt. Chem., 1947, 19, 423; A. Steyemark,Anal., 1946, 18, 710.Id. E w . Chem. Anal., 1945,17,523INGRAM AND WATERS : ANALYSIS OF ORGANIC COMPOUNDS. 281on the whole, now regarded as safe for routine work with compounds of knowncharacteristics. Amongst these, attention may be directed to the semi-micro apparatus of F. 0. Fischer * which is of the Pregl type, and is claimedto give an absolute accuracy of &0.02% provided that compounds of widelydiffering hydrogen content are not burned consecutively.Several modifications of the standard Pregl technique of micro-combustionhave aimed a t hastening the whole operation by employing a faster gas flowthrough the tube, and the extreme limit in this direction would appear tohave been reached by V.L. Les~her,~ who allows hydrocarbon vapours toinflame in an oxygen stream of velocity 300 ml./minute. R. Belcher andC. E. Spooner's method 6-first developed for coal analysis ' f o r thecombustion of organic substances in oxygen in an empty silica tube main-tained at 800" has also been advocated by Russian workers s and has beentested critically for the analysis of compounds containing only carbon,hydrogen, and oxygen.G. Ingram9 found it necessary to place a plugof copper oxide, or preferably silica wool, in the hot tube to prevent thepassage of particulate carbon, and A. F. Colson lo has used a silica spiral toensure the complete oxidation of the combustible gases. However, E. C.Horning and N. G. Horning 11 and P. Gouverneur l2 have shown that inanalysis on a centigram scale good results can be obtained in packed tubeswith flow rates of oxygen, or air, of as much as 25-50 ml./minute. Timeonly will show whether these rapid-flow methods will ultimately replace thepresent standard procedures, for they may not prove to be applicable for theanalysis of very volatile, or thermally unstable, substances.Much attention has been given to the removal of the oxides of nitrogenwhich are formed in the combustion of all nitrogenous substances, especiallyif they are burnt in oxygen rather than in air,l3 and, more particularlywhenever catalytic tube fillings, such as platinum, are used.Since leaddioxide is often considered to be a source of error in the determination ofcarbon and hydrogen, in that some preparations yield high blanks and behavecapriciously with regard to their equilibrium between water and carbondioxide contents of the flowing gases, the use of an external absorbent foroxides of nitrogen has often been advocated. A. E. Heron,14 who hasdealt with the combustion of aliphatic nitro-compounds, increases thelength of the lead peroxide layer inside the tube and, in certain cases, supple-ments it by a spiral bubbler containing chromic acid-sulphuric acid mixture,which he places after the water absorption tube.Liquid absorbents forInd. Eng. Chem. Anal., 1949, 21, 827.J., 1943, 313.M. 0. Korshun and V. A. Klimova, Zhur. Anal. Khim., 1947, 2, 274 (abst. inAnalyst, 1948, 73, 351); M. 0. Korshun and N. S . Sheveleva, C m p t . r e d . (DokZady)Acad. Sci. U.S.S.R., 1948,60,63 (Chem. Abs., l948,42,6270d).lo Ibid., p. 541.Ibid., p. 1247.Fuel, 1941, 20, 130.* Analyst, 1948, '43, 548.l1 Analyt. Chem., 1947, 19, 688.l8 Anal. Chirn. Acta, 1948, 2, 510.l8 A. E. Heron, A&y8t, 1947, 72, 142.l4 Ibid., 1948 73, 314282 ANALYTICAL CHEMISTRY.nitrogen oxides have been used by many others 99 11, l5 in conjunction withthe rapid-flow methods, though Colson lo places a second lead peroxide tubefor this purpose between the water and the carbon dioxide absorptiontubes. External absorbents can be used only when water produced duringthe combustion is prevented from condensing in both the beak end of thecombustion tube itself and in the inlet of the weighed anhydrone tube.Any liquid water in either of these positions would retain nitrogen oxides,and so vitiate the hydrogen figure.In the rapid-flow methods the fast gasstream drives the water vapour well into the desiccant layer before there isany condensation; in the conventional combustion method this is difficultto ensure, and consequently lead peroxide with all its potential failingsis often preferred still.16 A. Bennett,17 however, has eliminated the use oflead peroxide by using nitrogen containing only a little oxygen as the carriergas, and packs his tubes with a layer of copper oxide followed by one of re-duced copper.This departure from the current method of burning substancesin pure oxygen in the presence of oxidation catalysts is a return to theconceptions of Liebig and Dumas which, in view of Heron's findings,l3*14may prove to be particularly valuable for the analysis of nitro-compoundsand the like.It now seems to be agreed that a heated silver packing, if long enough,is adequate for the removal of both halogens and sulphur. The fouling ofcombustion tubes through the volatilization of silver halides is still, however,one of the major drawbacks of micro-combustion for which, as yet, no remedyhas been proposed.Determination of Nitrogen.--In connection with the Dumas method afew modifications in the design of apparatus can be noted.W. K. Noyce l8back-flushes the combustion tube with carbon dioxide when refilling betweenanalyses, and so saves time in routine work. Other workers l9 haveimproved the designs of micro-nitrometers so as to rninimise the foulingaction of the concentrated potassium hydroxide.The Kjeldahl method continues to receive much study, especially inconnection with protein analysis. Mercuric sulphate,2O selenium, andselenium dioxide 21 appear to be the favourite oxidation catalysts, andboric acid solution continues to gain favour as the absorbing agent.In astatistical study of the Kjeldahl method, P. E. Machemer and W. M. &Nab 22find that steam-distillation of the ammonia is much safer than direct boiling.l5 A. Etienne and R. Mileur, Ann. Chim. analyt., 1946, 28, 215; I. Irimescu and B.l6 R. 0. Clark and G. H. Stillson, Ind. Eng. Chem. Anal., 1945,17,520.l7 Analyst, 1949, 74, 188.Popescu, 2. anal. Chem., 1948,128,185.l8 Arurlyt. Chem., 1949, 21, 877.E. Stehr, Ind. Eng. Chem. Anal., 1946, 18, 513; A. Muller, Mikrochem., 1947, 33,2o A. Hiller, J. Plctzin, and D. D. Van Slyke, J. Biol. Chem., 1948, 176, 1401; R. L.21 G. Frey, Helv. Chim. Acta, 1948, 31, 709; R. Jonnard, Ind. Eng. Chem. Anal.,2a Aruzlyt. Chim. Acta, 1949, 3, 428.192.Shirley and W.W. Becker, I n d , Eng. Chem. Anal., 1946, 17, 437.1945, 17, 246INGRAM AND WATERS : ANALYSIS OF ORGANIC COMPOUNDS. 283R. Chand,23 however, advocated distillation in a closed system, and I(.Marcali and W. Rieman 24 have eliminated the distillation altogether byneutralising the digestion mixture and then titrating the ammonium salt toa second end-point with phenolphthalein after adding formaldehyde.Potassium bi-iodate, KH(IO,),, has also been proposed as a receiver for theammonia, which can then be titrated with thiosulphate, after addition ofpotassium iodide and starch indicator.25 P. McG. Shuey 26 has again directedattention to the fact that chlorides may cause loss of nitrate nitrogen, byvolatilization of nitrosyl chloride, when the usual Kjeldahl method is usedfor determining total nitrogen in organic matter.Determinations of Halogens and of Sulphur,-Micro-chemical modifi-cations of almost every current method of halogen or sulphur analysis havenow been proposed, but only a few of these seem to merit special note.M.A. M. Fleuret 2' has developed an interesting centigram-scale methodof fusion analysis. He decomposes his compounds in molten silver nitrate,and thus obtains silver halides which can be weighed directly, whilst silversulphate, or arsenate, can be extracted with ease. Granulated magnesia,has been advocated for the fusion analysis of chlorides,28 and calcinedmanganite for use with iodides.29 Good accuracy is claimed for modificationof the Stepanov method,30 and catalytic reduction using Raney nickelhas been advocated for use with chlorides or bromides other than volatilearomatic ~ubstances.~~Much attention has been paid to the determination of fluorine in organiccompounds.Several workers 32~33 combust fluorides in silica tubes contain-ing quartz chippings. If it is desired to estimate carbon a t the same time,the silicon fluoride thus formed can be absorbed on aluminium oxide kepta t 175" and weighed, whilst simultaneously chlorine can be retained on silverwool and weighed as silver chloride.33 Potassium fluoride, which formsK,SiF,, is another absorbent for fluorine in elementary analysis for carbon.32For fluorine estimation, however, the silicon tetrafluoride is usually collectedin a bubbler containing water, or alkali, after which i t may be estimatedgravimetrically as PbClF or titrated with thorium nitrate.34 An improvedprocedure for this uses Solochrome-blue as indicator.3524 Ind.Eng. Chem. Anal., 1946,18, 709.27 Bull. SOC. china., 1945, 12, 133.z8 J . Indian Chem. SOC., 1947, 24, 167.25 R. Ballentine and J. R. Gregg, Analyt. Chem., 1947,19, 282.26 Ibid., p. 882.28 J. Anelli, Rev. farm. (Buenos Aires), 1945, 87, 61.2s A. Horeau, Compt. rend., 1946, 220, 89.30 A. K. Ruzhentseva and V. S. Letina, Zhur. Anal. Khirn., 1948, 3, 139 (Chem.Abs., 1948, 42, 7656f); K. Shishido and H. Sagi, Analyt. Chem., 1948, 20, 677; J.Decombe, Bull. SOC. chim., 1948, 38, 353.*l M. Pesez and P. Poirier, ibid., p. 379; A. Schwenck, I d Eng.Chem. Anal., 1943,15, 576.s2 N. S. Nikolaco, Chern. Age, 1946, 54, 309.3s R. D. Teston and F . E. McKenna, Analyt. Chem., 1947,19, 193.sa R. H. KimbalI and L. F. Tufts, ibid., p. 150; MT. C. Schumb and K. J. Radimer,$bid., 1948, 20, 871.R. F. Milton, H. F. Liddell, and J. E. Chivers, Analyst, 1947, 78, 43284 ANALYTICAL CHEMISTRY.On the micro-chemical scale J. F. Alicino, A. Crickenburger, and B.Reynolds 36 have reintroduced Van der Meulen's iodimetric method 37 fordetermining bromine, after the catalytic combustion of an organic bromide.The bromine is collected in sodium hydroxide solution, and then oxidised tobromate with sodium hypochlorite. Excess of the reagent is removed bybuffering with sodium dihydrogen phosphate and then boiling with sodiumformate, and the bromate is finally decomposed with potassium iodide and atrace of ammonium molybdate.G. L.Stragand and H. W. Safford38 determine sulphur, after catalyticcombustion, by absorption on weighed silver gauze, kept a t 650". In thepresence of halogens, other than fluorine, the weighed silver is extractedwith boiling water, and the amount of leached silver sulphate is then foundby difference. In sharp contrast to this, M. 0. Korshun and N. E. Helman 39decompose sulphur compounds in hydrogen, using a platinum catalyst,absorb the hydrogen sulphide in an acetic acid solution of zinc sulphate,and finally titrate iodimetrically. The Carius and Burgess-Parr bombmethods for sulphur analysis have been completed by the use of knownvolumetric methods of sulphate determinati~n.~~Determination of Oxygen.4.Unterzaucher's direct method of con-version of oxygen into carbon monoxide 4 1 has now been modified to analysison the centigram scale and an accuracy of 0.2% is now claimed for it.42Helium has been used in place of nitrogen as the carrier gas.43 The method,however, still seems to be outside the scope of most laboratories.Group Analysis.-Modifications of the Zeisel procedure have beendescribed by D. 0. Hoffman and M. L. Wolfrom44 for the determinationof alkyloxy-groups in acetals and in easily volatile alcohols in which thesamples are carefully introduced below the surface of the reaction mixture.By using an electrically heated bath and a water condenser maintained at40°, H.E. Fierz, D. E. Pfanner, and F. Oppliger 45 claim to be able to estimatealkyloxy- and alkylimino-groups to an accuracy of .+0.2%, and also todetermine methoxyl and ethoxyl separately. They use nitrogen rather thancarbon dioxide as the carrier gas.R. GI.. Stuart 46 has made a useful study of the trans-esterification reactioninvolved in acetyl group determination, and other workers have described86 Analyt. Chem., 1949, 21, 755.37 Chem. Veekblad, 1931, 28, 238; 1934, 31, 558.3* Analyt. Chem., 1949, 21, 625.39 Zavod. Lab., 1946,12, 754 (Chem. Abs., 1947,4l, 3326e).40 E. C. Wagner and S. H. Miles, Amlyt. Chem., 1947, 19, 274; A. Sfeyerm~rk,41 Ber,, 1940, '73, 391.42 V. A. Aluise, R. T. Hall, F. C. Staats, and W. W. Becker, Analyt.Chem., 1947,43 W. W. Walton, F. W. McCulloeh, and W. H. Smith, J . Res. Nut. Bur. Stand.,44 Analyt. Chem., 1947,19, 225.46 Helv. Chim. Acta, 1946, 20, 1463.48 AnaZyst, 1947, 72, 235.E. Bass, and B. Littman, ibid., 1948, 20, 587.19, 347; R. A. Dinerstein and R. W. Klipp, ibid., 1949, 21, 545.1948, 40, 443SMALES : RADIOAU!I!IVA~ON ANALYSIS. 285modifications of the normal procedure.4'7 4* R. B. Bradbury,48 for instance,is a strong advocate of the use of toIuene-psulphonic acid, and titrates theacetic acid iodimetrically, making a correction for any sulphur dioxide by ablank determination.For determination of hydroxyl groups the method of acetylation withacetic anhydride in pyridine, and subsequent titration of the unused reagentafter decomposition with water, now appears to have won general favour.Potentiometric titration greatly increases the accuracy of this analysis 49except for colourless solutions.Primary and secondary amines thiols,and some aldehydes interfere seriously with this procedure.A few modifica.tions of the Zerewitinoff method of determining activehydrogen have been describedJ50 and lithium aluminium hydride has beenproposed as an alternative reagent.51G. I.W. A. W.6. RADIOACTIVATION ANALYSIS.Although radioactivation analysis was first used in 1936, it is still in theearly stages of development and indeed this subject has not been previouslyreported on as a special technique of analysis. The basis of the method,the advantages offered, and the possibilities of applying it will therefore bediscussed rather more fully than is customary in these Reports.andsince reviewed by B.Goldschmidt? G. T. Seab~rg,~ G. E. Boyd: and L.T ~ r d a i , ~ is simple; an element is detected and determined by the formationof a radioactive isotope, which can then be subjected to radioactive assay, aprocedure with the inherent possibilities of extreme sensitivity and specificity.Theory.-If an element is placed in a homogeneous flux of constantenergy of positively charged particles or neutrons, then the rate of growthof the number of radioactive atoms N* with time is given byThe essential basis of the method, suggested by G. von HevesydN*/dt = fC,,+N - AN*which on integration for the period of irradiation becomesN* = ~ c ~ ~ .N ( 1 - e-At) /AI f E. Weisenberger, Mikrochem. Mikrochim. Acta, 1947, 33, 51.48 Analyt. Chem., 1949, 21, 1139.C. L. Ogg, W. L. Porter, and C. 0. Willits, Ind. Eng. Chem. Anal., 1945,17, 394;A. Robertson and W. A. Waters, J., 1948, 1585.so A. P. Terentev and K. D. Shcherbakova, J . Gen. Chem. U.S.S.R., 1946,16, 855;R. H. Lehman and H. Basch, Ind. Erq. Chem. Anal., 1945, 17, 428; P. M. Maginnityand J. B. Cloke, Analyt. Chem., 1948, 20, 978.61 H. E. Zaugg and B. W. Horron, ibid., p. 1026.Kgl. Danske Videnskab. Selskab., Math.-fys. Medd., 1936, 14, [ 5 ] ; 1938, 15, [ll].Bull. Soc. chim., 1939, 6, 718.Amlyt. Chem., 1949, 21, 335.Chem. Rev., 1940, 27, 266.Atomics, 1949, 1, 101.* E. Pollard and W. L. Davidson, '' Applied Nuclear Physics," New York, J.Wiley& Sons, 1942286 ANALYTICAL CHEMISTRY.where f is the flux of bombarding particles in units of particles/sq. cm./sec. ;is the isotopic cross section for the nuclear reaction in units of sq. em. pertarget atom; N is the number of target atoms; and A is the radioactivedecay constant which is connected with the half life T,,, by the relationA = 0*693/T,,,.The amount of activity At, in disintegrations per second, exhibitedby the atoms N* produced up to a time t , is given by the expressionAt = AN* = foac.j'jT(l - e-ht) = fo,,J7 (1 - e-0693tiT11~ )So far it has been assumed that the element is monoisotopic; however,considering a weight W g. of an element of atomic weight M , if 6 is theabundance of the particular isotope giving rise to the activity, then the abovebecomesAt =foa,.6W x 6 x 1023 (1 - e-0693t/T~f~ ) /J!fThe factor (1 - e-0693t1T1rt) has been called the saturation factor, 8,which may vary between zero and unity, having a value of Q when the irradi-ation time t is the half-life T,,,.After the irradiation is stopped the activityformed will decay with its characteristic half-life. A quantitative descrip-tion of this is given by E. Rutherford, J. Chadwick, and C. D. Ellis.' Thusfor high activity for a given mass, there should be high values for the fluxand activation cross-section ; while if other things are equal then sensitivityis greater for lower atomic weight elements, and those with high relativeabundance of the particular isotope concerned.The half-life of the isotopeformed does not control the inherent sensitivity of the method. It can,however, be a practical limitation where long irradiation times are necessaryto obtain sufficient activity.The character of radiation emitted by the active isotope formed mustalso be considered in evaluating the sensitivity for a particular isotope.Boyd discusses this in more detail. In general, unless specialised detect-ing equipment is employed, the greatest sensitivity in activation analysiswill be attained when @-particle radiation is measured.General Practical Technique.-From the foregoing, it is seen that, pro-vided the magnitude of the flux, reaction cross-section, and half-life are known,a determination of the absolute disintegration rate should enable the calcula-tion of the absolute mass of the constituent to be determined.However,accurate knowledge of the flux and accurate determination of the absolutedisintegration rate are not always possible, but in practice these difficultiesmay be avoided by making use of a comparative procedure, i.e., the simul-taneous irradiation of samples with standards of the same general com-position, a device quite common in analytical chemistry. After irradiation,if chemical separations are necessary, the samples and standards are dissolved,inactive carrier for the constituent desired is added (and also usually hold-back carriers for other active elements to prevent difficulties from adsorption,etc., as in conventional radiochemical practice), the necessary chemical' " Radiations from Radioactive Substances," Cambridge Univ.Press, 1930SMALES : RADIOACTIVATION ANALYSIS. 287separations performed, and then aliquots mounted for radiochemical assay.Where the chemical yield is not quantitative, a correction may usually beapplied from a knowledge of the mass of inactive carrier added and thatfinally isolated, the latter being measured by any usual analytical techniquebut most often gravimetrically. Corrections for self absorption of theradiation may be necessary if the weights of samples and standards assayedare different, particularly if weak @-emitters are being measured.8 Thenthe mass of X, the constituent originally to be determined, is obtained bycomparing corrected counting rates of samples and standard thus :Total activity from element X in unknown __ mass of X in unknownTotal activity from element X in standard - mass of X in standardNormally the radiochemical purity of the samples and standards wouldbe checked by absorption and decay measurements.Requirements.-The requirements other than the usual analyticalfacilities are obviously (a) an activation source and (b) a counting mechanism.Dealing with ( b ) first, there is now commercially available in this countrystandard p-counting equipment comprising Geiger-Muller tube, usuallyof the end-window type, and lead castle for shielding i t ; a power pack forsupplying the high voltage necessary for the tube, and a scaling unit forchoosing a proportion of the counts to be fed into a counting meter usuallyof the Post Office type.So far as (a) is concerned, the various types and their advantages and dis-advantages will be dealt with individually, special emphasis being laid on thetwo generally available possibilities, i.e., the laboratory radium-berylliumor other similar neutron sources, and the chain reacting pile.Laborcztory Neutron Sources.-These depend upon the bombardment ofberyllium either by a-psrticles from radium (or radon) or polonium, or byy-radiation of maximum energy greater than 1.63 Mev., such as that fromartificially prepared 60-day lz4Sb ::Be + :He ---+ 'ZC + in + 1-6 MeV.:Be + hv _t :Be + inPolonium and antimony both have the disadvantage that they are relativelyshort-lived, decaying with half-lives of 139 and 60 days, respectively, althoughthe former has the great advantage of emitting very little radiation other thana-particles, and hence shielding is much simplified.Because of general availability, however, the radium-beryllium sourceas a permanent unit is useful, and a description of its use for demonstratingactivation has been given by W.H. Hamill, R. R. Williams, and R. H.S ~ h u l e r . ~The slow neutron flux obtainable with a 500-mg. radium-berylliumsource in ~ l . paraffin-wax moderator is of the order of lo4 neutronslsq. cm./sec.and an example of the usefulness of this can be given. The most sensitiveW. F. Libby, Analyt. Chem., 1947,19, 2. J . Chem. Educ., 1949,26, 210, 310288 ANALYTICAL CHEMISTRY.example is lMDy which has a natural abundance of 27.6% and an activationcross-section of 2620 barns (Le., 2620 x sq.cm.) for slow neutrons,lOand the product of its activation, ‘;:Dy, has a half-life of 2.5 hours.The activity to be obtained per g. of natural dysprosium on irradiationto saturation, i.e., for a few days, will belo4 x 2620 x 10-% x 0-276 x 1 x 6 x x 60164 AE == 1-6 x log dis./min. per g.or if irradiated only for one half-life, i.e., 2.5 hours, the activity obtainedwould be 8 x lo5 dis./min./g. The reasonable assumptions being madethat a normal Geiger counting apparatus will register 10% of the p-particlesemitted from the 165Dy and that 8 counts/min, registered above background(-8 c./m.) is a reasonable figure for positive determination, then i t may beseen that 0-1 mg.of dysprosium will be determinable immediately afterirradiation.There are several elements with activation cross-sections and isotopeabundances which can give useful results, though with somewhat lowersensitivity than dysprosium, with the radium-beryllium source, e.g., Ag,Au, Eu, Ho, In, Ir, Lu, Mn, Pr, Re, Rh, Sc, Sm, Ta, Tb, Tm, Yb, W, all havevalues for the product 8 x aae. of >10 (cf. 720 for Dy). On the other hand,there are a number of elements from which practically no activity can bedetected after irradiation for a short period followed by a short time for decay.This is the case with, e.g., Al, B, Be, C, Cb(Nb), F, Fe, Li, Mg, N, Ne, 0, S,Sn, Ta, Ti, T1, V, where the element has either a low cross-section or anexceptionally long or short half-life.Thus it becomes feasible to determinein one or other of these elements small amounts of those listed above.A summary of the slow neutron atomic activation cross-sections (i.e.,product of fractional natural isotope abundance and isotopic activationcross-section) is given by Boyd: and fuller information is available fromSeren et aZ.10 or from I(. Way and G. Haines.llIt can be seen from these examples that, even without chemical separationin some wses, the Ra-Be source makes possible certain otherwise difiEicultanalytical determinations, e.g., rare earths, rare metals, etc., but in generalthe 500-mg. Ra-Be source is useful only for quantities of the order of milli-grams of the favourable elements.Some applications have been reported,e.g., von Hevesy and H. Levi1 determined dysprosium in yttrium, andeuropium in gadolinium, and B. Goldschmidt and L. Meitner l2 have alsoused this method for rare earths, and R. Dope1 l3 has discussed the determin-ation of iridium in platinum.The Atomic Pile (Nuclear Reactor) as a Neutron Source.-This may be10 L. Seren, H. N. Friedlander, and S. H. Turkel, Physical Rev., 1947,72, 888.11 “Thermal Neutron Cross Sections for Elements and Isotopes H-Bi,” 17.5.1st Ark. Mat. Astr. Fys., 1941, 27, A , Pt. 3, No. 17, 1-18.Atomic Energy Commission, AECD-2138.Phydkal. Z., 1945, 44, 261S U E S : RADXOAOTIVATION ANALYSIS. 289considered as an available source since irradiation facilities are availablein this country on request.14Considering first thermal neutrons only, the general discussion givenunder “ Laboratory Neutron Sources ” applies, except that in the Harwellpile, a flux of more than 1011 neutronslsq.cm./sec. is available. If this iscompared with the figure of lo* neutronslsq. em. Isec. previously discussed,which gave a sensitivity of milligram quantities for certain elements, it canreadily be seen that amounts of 10-10 g. or less become determinable. It isthis enormous potential sensitivity coupled with the specific identification,by half-life and energy, of the particular isotope formed, which really givesthis method its attraction. A further attraction is the possibility of over-coming one of the troublesome analytical difficulties in the normal handlingof such small quantities of materials as 10-6 g.or less, i.e., loss by absorption.In the case of radioactivation analysis, once the irradiation is completedit is quite permissible to add relatively large quantities of the inactiveelement concerned, and provided exchange between the active and theinactive isotope is established, the problem of handling sub-microgramquantities disappears.With these higher fluxes the scope of analytical determinations indicatedon p. 288 must be modified, and reference should be made to the full lists l o p ll.for the evaluation of particular problems, although it still remains generallytrue that slow neutron activation analysis will not be possible for the lighterelements because of their very low cross-sections and the short-lived isotopesformed.Thus,Boyd lists the detection of potassium and cmium in sodium salts by resolu-tion of the decay curve, the analysis of mixtures of sodium and potassiumby differential absorption measurement (using the difference in maximumenergy between %Na, max.@-energy 1.39 Mev.; *2K, max. @-energy3 6 8 MeV.), the analysis of a manganese-aluminium alloy for manganese(cf. H. M. Clarke and R. T. Overman 15), and the interesting determinationof stable isotope abundance ratios for copper and chlorine.16 Other examplesare the determination of traces of thulium in erbium,l7 the gallium andpalladium contents of iron meteorites,18 the relative abundance of rheniumin Nature,19 and the analysis of the micro-composition of biological tissue.20A brief mention is made of the analysis of zirconium-hafnium contents ofmixtures of their oxides.21 The use of activation for qualitative analysisExamples of the use of the pile in this way are now appearing.l4 “ Radioactive and Stable Isotopes,” available from Isotope Information Office,16 U.S.Atomic Energy Commission, MDDC-1329.J. W. Kennedy and C. T. Seaborg, PhysicaZ Rev., 1940, 57, 843.1 7 B. H. Ketelle and G. E. Boyd, J . Amer. Chem. SOC., 1947, 69, 2800.H. Brown and E. Goldberg, U.S. Atomic Energy Commission, AECD-2296.l@ Idem, PhysicaZ Rev., 1949, 76, 1260.*O C. A. Tobias and R. W. Dunn, U.S. Atomic Energy Commission, AECD-11 S . A. Reynolds, G. C. Bell, and C. 0. Muelhouse, AnuZyt.Chem., 1949,21, 1214.A.E.R.E., Harwell, nr. Didcot, Berks.2099-B.BEP.-VOL. XLVT. 290 ANALYTICAL CHEMISTRY.is illustrated by R. Lindner,22 who irradiated yttrium rare earths beforepassing them through an ion-exchange column. The special case of detectionof fissionable elements by slow neutron activation (followed by detectionof fission products) must also be mentioned.The discussion so far has been concerned only with slow neutrons, forwhich in general the reaction is the straightforward capture of a neutron(n-y reaction) t o give an isotope of the same element with an increase inmass of one unit. However, other nuclear reactions can occur in the pile,more particularly if there is any appreciable fast neutron flux at the siteof irradiation.These processes can be either advantageous or otherwise.The disadvantage is that active products other than those expected mayarise due to n,p, n,a, n,Zn, etc., reactions (see, e.g., Pollard and Davidson 23for fuller discussion), thus necessitating possible modification of the chemicalmethods for isolation of the element desired and making the comparativerather than the absolute technique necessary. A discussion of the con-taminants arising from these and other factors both for pile and cyclotronirradiation is given by W. E. Cohn.24 The advantage is in the possibleextension of the method to those elements which do not give suitable isotopesby the n,y reaction. A useful example of this is the detection of oxygenor lithium. When these two elements are irradiated with slow neutronstogether, e.g., as lithium carbonate, the lithium undergoes a unique reactionOLi + ln --+ *He + 3H; the tritons so produced react with the oxygenproduced, whereas normal slow-neutron irradiation of either lithium oroxygen separately gives no suitable active isotope.Other SOurces.-Other sources, e.g., the cyclotron, with its flux possi-bilities at least as high as those in the pile, and the electrostatic generator(both with their possible variation of bombarding particle), are attractiveand have been used for activation analysis.Thus G. T. Seaborg and J. J.Living~od:~ using cyclotron deuterons, detected 6 p.p.m. of gallium in iron,and also demonstrated the presence of small amounts of copper in nickel,iron in cobalt, and phosphorus and sulphur in various substances. D.T. P.King and W. J. Henderson 26 used a-particles to activate traces of copper insilver by the a-n reaction (;$XI + :He I_, :;Ca + in and ;~CU + :He --+",Ca + in), and R. Sagane, M. Eguchi, and J. Shigata 27 used deuterons todetect 10 p.p.m. of sodium in aluminium (23Na + 2H --+ 24Na + lH).M. von Ardenne and F. Bernhard,28 using an electrostatic accelerator toproduce deuterons, determined carbon in steel down to 0.05%.Some disadvantages must be mentioned, e.g., the extreme care requiredowing to the introduction of small amounts of impurities from recoil atoms16 ,O + iH + ':F + in. Active fluorine (half-life, 112 mins.) is thus22 2. Naturforsch., I, 1946, 67.24 " The Origin, Detection, Identification, and Removal of Radioactive Con-25 J .Amer. Chem. Soc., 1938, 60, 1784.27 J . Phys. Math. Xoc. Japan, 1942, 16, 383.28 2. Physik, 1944,122, 740.25 Ref. (6), pp. 75 et seq.taminants in Tracers," U.S. Atomic Energy Commission, MDDC- 1643.28 Physical Rev., 1939, 56, 1169SPENCE : GAS ANALYSIS : CHEMICAL METHODS. 291and v~latilization.~ The heat to be dissipated, and the rather small areaavailable in using a cyclotron beam impose limitations on the type and sizeof material which can be irradiated. In general, activation cross-sectionsusing fast neutrons or charged particles are lower than those for slow neutrons ;and, for high-energy particles, the multiplicity of nuclear reactions which mayoccur simultaneously are unfavourable from the analytical viewpoint.It is not intended to deal in detail with these sources here, however, sincethey cannot as yet be regarded as being generally available.Their possi-bilities in giving more favourable nuclear reactions, in some cases, than thepile must not be overlooked, and in considering whether the activationmethod is applicable for individual cases it is worth remembering all thepossible reactions with both neutrons and charged particles. A full list ofthe isotopes with the nuclear reactions involved and the original references,is given by G. T. Seaborg and I. Perlrnax~.~~Finally, the extension of the use of this method may depend to a largeextent not only on the wider provision of suitable sources, but also on theavailability of rapid and specific isolation procedures, Le., the new toolpresented to the analytical chemist at the same time brings its own challenge.A. A.S.7. GAS ANALYSIS.(i) Chemical Methods.Considerable effort has been made of recent years towards the improve-ment of existing methods of gas analysis, and the period has also beennotable for the appearance of a number of essentially new techniques.The subject has been reviewed by V. J. Altieri 1 and the standard pro-cedures have been described in a series of articles by W. D. Vint.2 A detailedaccount of a representative selection of micro-methods is also given byK. M. Wilson in “ Methods of Quantitative Micro Analysis.”The methods of most general applicability still largely depend on pro-cesses of combustion or chemical absorption.The well-known Orsatapparatus, for instance, which was brought to a high degree of refinementby M. Shepherd,* has recently been modified by the introduction of anabsorption train consisting of a series of glass loops containing smallquantities of liquid or solid absorbents, the liquid absorbents being held ona length of wick or similar material wound round a glass rod. The gassample, which can be considerably smaller in the modified apparatus, ispassed back and forth round the loop until reaction is complete.According to H. W. Deinum and J. W. DamY6 there is it loss of accuracyin the determination of methane and ethane with the standard Orsatz0 Rev. Mod. Physics, 1948, 20, 585.New York : American Gas ASSOC., 1945.Metallurgia, 1947,35, 153, 255, 294; 36,47, 157, 276, 333; 37, 317.Collected and edited by R. F. Milton and W. A. Waters, Edward Arnold & Co.,London, 1949.4 J . Res. Nat. Bur. Stand., 1931, 6, 121.6 M. Shepherd, ibid., 1941, 26, 351. Anal. Chim. Acta, 1948,2, 50292 ANALYTIOAL CHEMXSTBY.apparatus owing to absorption of carbon dioxide by copper oxide, etc.They have shown, however, that copper oxide does not absorb carbondioxide a t 800°, nor does it give up appreciable quantities of oxygen a t thistemperature; only 0.01 ml. was picked up by a stream of nitrogen in 10minutes. The cooler ends of the copper oxide tube should therefore bepacked with quartz to avoid uptake of carbon dioxide and correctionsshould also be applied for deviations from the perfect-gas law.Othermodifications of the general design and new forms of absorption equipmenthave also been pr~posed.~The Haldane apparatus, t o which the Orsat apparatus is closely related,still continues to be widely used.8 Details of a special form of stopcockdesigned to reduce dead space are given by F. S. Cotton? together withoperational instructions leading to greater accuracy. In the case wherethe sample is completely absorbable, use of a subsidiary burette containingnitrogen, which can be introduced as a diluent in the later stages, is alsorecommended. loThe Bone and Wheeler constant-volume gas-analysis apparatus hasbeen in use a t the Fuel Research Station for many years, and L. J.Edge-combe l1 has given an account of the equipment, reagents, and analyticalprocedure which have been adopted. Other constant-volume proceduresare described by Z. Szabo and I. Soos,12 by G. Wagner,13 and by P. T.Sprague, C. A. Sprague, and A. Soller,14 who use an absorption systemcontaining steel-wool wetted with a suitable reagent. C. H. Bamford andR. R. Baldwin 15 have developed a constant-volume type of apparatus inwhich the gas is removed from the measuring bulb by means of a Toplerpump and passed round a circuit containing liquid-air traps and a copperoxide tube or a platinum spiral. After removal of the uncondensed gas,carbon dioxide can be separated from the condensate by raising the tem-perature to -78", and its pressure determined after transference to themeasuring bulb.An accuracy of -&0.03% is claimed. This apparatuscan, if necessary, be used for semi-micro-work. Other types of semi-micro-apparatus have been described by R. K. Goltz and by S. G. Demidenkoand B. A. Geller.16 Details of a modified form of the manometric VanSlyke apparatus are given by M. Shepherd and E. 0. Sper1ing.l' Thereagent is forced into the absorption vessel by mercury, producing a fountainL. L. Vaydaand J. A. Stein, B.P. 601,018/5.9.44; C. A. Sprague, Assr. to HaysCorpn., U.S.P. 2,312,285/23.2.43; P. T. Sprague and C. A. Sprague, V.S.P. 2,180,322114.11.39; C. M. Blair and J. H. Purse, Id. Eng. Chem. Anal., 1939,11, 166; A. R.Anderson, ibid., 1946,18, 70.See, e.g., H. Enghoff, Acta Medica Skand., 1946, Suppl.1'90, 307.J. Lab. Clin. Med., 1939,24, 1178.lo H. C. Bazett, J . Biol. Chem., 1941,139, 81.Fuel, 1946, 25;, 163, 171.l2 2. anal. Chem., 1943, 126, 219, 22.'* U.S.P. 2,179,867/14.11.39.l7 J , Res. Nat. Bur. Stctnd., 1941, 26,341.1s Oesterr. Chem.-Ztg, 1940, 43, 71.l5 J., 1942, 26.Zavod. Lab., 1939, 8, 1078; 1948,14, 601SPENCE : GAS ANALYSIS : CHEMIUAL METHODS. 293which gives very rapid absorption. The addition of reagents to the VanSlyke apparatus can be simplified by substituting a syringe pipette for theusual Hempel type of pipette.18An entirely new form of gas-analysis apparatus, consisting of a trainof absorption or reaction vessels each having a soap film flow-meter im-mediately following it in the train, has been developed by W.J. Gooderham.l9The gas entering the flow-meters can be either by-passed or switched to thecalibrated soap-film tube. All the soap-film tubes can be switched on oroff together, thus permitting an instantaneous reading of the volume changesoccurring in the gas due to passage through the various reagent tubes.Conventional absorbing solutions or oxidation systems are used, andthe absorption tubes consist of a. glass spiral down which the solutionflows.The determination of individual constituents of gas mixtures has beenthe subject of numerous papers. The use of the copper sulphate-p-naphtholreagent for carbon monoxide has been discussed by J. I. Tscherniaeva20and by L. B. Berger,al and a gravimetric determination utilising the reactionbetween carbon monoxide and red mercuric oxide at 175-200°22 is ofsome interest on account of the highly advantageous gravimetric factor(7.14) arising from the distillation of the mercury produced in the reaction.Determination of carbon dioxide in fuel gases by preliminary condensationin a liquid-air trap and subsequent transfer to an apparatus similar to thatof C.H. Bamford and R. R. Baldwin l5 is claimed by R. R. Baldwin 23 tobe accurate to 0.001 yo for small carbon dioxide concentrations and to0.25 % for higher concentrations. Combustion of hydrogen, carbonmonoxide, and methane by means of palladised asbestos 24 and platinisedsilica gel 25 has been recommended, but various authors 26 have reporteda reaction between platinised asbestos or a platinum wire and oxygen whenheated above 700".An error due to this reaction can be avoided if com-bustion mixtures deficient in oxygen are used. The determination ofacetylene colorirnetrically by means of the Ilosvay reagent 27 and titri-metrically after reaction with potassium mercuric iodide 28 has also beendiscussed. Fluorine has, of recent years, become increasingly importantboth industrially and in the laboratory. The determination of Auorine ingas mixtures can be conveniently carried out by displacement of brominela R. Wennesland, Skund. Arch. Physiol., 1940, 83, 201.l9 J . Soc. Chem. Id., 1940, 59, 1; Analyst, 1947, 72, 520.2o Zuvod. Lab., 1939, 8, 1092.21 U.S. Bureau of Mines, 1947, Rept. Invest. 4187; see also P. R.Thomas, L. Down,a2 J. D. XlcCullough, R. A. Crane, and A. 0. Beckman, {bid., 1947, 19, 999.24 R. Vandoni, Mdm. Sew. chim. de l'ktut, 1943,30,18, 272.25 K. A. Kobe and R. A. McDonald, Ind. Eng. Chern. Anal., 1941,13,457.L. K. Nash, ibid., 1946, 18, 505; C. E. Ransley, Anaiyst, 1947, 7$2, 504.27 H. A. J. Pieters, Chem. VeekbEad, 1947, 72, 504.and H. Levin, Arutlyt. Chem., 1949,21, 1476.J., 1949, 720.F. R. Brooks, Anulyt. Chem., 1949, 21, 1433; J. G. Eanna and 8. Siggia, ib.td.,p. 1469294 ANALYTICAL CHEMISTRY.from sodium bromide and determining the bromine absorptiometrically,29or by displacement of chlorine from sodium chloride and determining thechlorine by absorption in alkaline arsenite solution with subsequenttitrati~n.~* Other components can be determined if the second method isused since the residual gas after absorption of the chlorine can be analysedseparately.When a high degree of accuracy is required, departures from the ideal-gas laws must be considered, and corrections have been calculated byJ.J. Leendertse and F. E. C. Scheffer 31 for a number of the more importantbinary mixtures. The correction does not exceed 0.2% in the case of mostcommon gases at 50 molecular per cent. at N.T.P. but rises to 0.6% forn- butane-nitrogen mixtures.Therehave been numerous variations of the original Krogh screw-controlledburette for analyses under constant pressure. Absorption tubes for usewith aqueous absorbents are described by J. A. Christiansen and I. Wulff,32who have also introduced a quartz hair-pin capillary immediately abovethe burette.Methane is quantitatively combusted when the hair-pin israised to a bright yellow heat. In the case of the well-known apparatusof Blacet and Leight0n,3~ in which the gaseous components are absorbedon solid reagents, the chief improvements reported 34 relate to the micro-burette. That described by s. s. Burke comprises a capillary microburetteand compensation tube immersed in a thermostated container with micro-meter-screw control of the mercury. An improved combustion coil hasbeen devised by R. N. Smith and P. A. L e i g h t ~ n , ~ ~ who also give detailsfor the analysis of nitric oxide-nitrogen, nitric oxide-hydrogen, and nitrousoxide-ammonia mixtures.P. F. Scholander36 has described a simple apparatus for the micro-analysis of respiratory gases, similar in principle to that due to T.C. S ~ t t o n , ~ 'in which the absorption chamber is an integral part of the burette. Thecapillary burette is vertical and has a small horizontal absorption chamber,open to the atmosphere, attached to the upper end. Reagents and gassamples are introduced and removed by means of small glass syringes andmercury displacement is read from a micrometer screw gauge. It is claimedthat 10 cu. mm. samples can be analysed with an accuracy of 0.1%. In amore elaborate apparatus,38 for samples of the order of 0.3 cu. mm., themenisci are observed by means of a dissecting microscope. Citrate solutions29 L. Nash, U.S. Atomic Energy Commission, MDDC-2158; E.Staple, J. G.30 R. H. Kimball and L. E. Tufts, U.S. Atomic Energy Cornmission, MDDC-195.31 Rw. Truv. chim., 1940, 59, 3.3% K g l . Dumke Videlzskab. Selskab., Mat.-fys. Medd., 1945, 22, No. 4, 23.33 Ind. Eng. Chem. Anal., 1931, 3, 266.34 D. C. Grahame, ibid., 1939, 11, 351; S. S. Burke, Analyt. Chem., 1949, 21, 633.35 Ind. Eng. Chem. Anal., 1942, 14, 758.36 Rev. Xci. Imtr., 1942, 13, 264.88 P. F. Scholander and H. J. Evans, J . Biol. Chem., 1947,169,651.Micro-methods of gas analysis have attracted much attention.Schaffner, and E. Wiggin, MDDC-1610.37 J . Sci. Instr., 1938, 15, 133SPENCE : GAS ANALYSIS : CHEMICAL METHODS. 295were found to be the best confining liquids. Another apparatus of this type 39with a piece of thermometer tubing as burette has been used for the analysisof between 0.3 and 1 cu.mm. of gas. In this case the confining liquid is asaturated solution of lithium chloride.A somewhat different constant-pressure apparatus, also due to P. F.S~holander,~~ comprises two absorption bulbs, a compensating bulb, anda microburette connected t o one another and to a multi-way stopcock, allmounted in a water-bath. The mercury in the burette is controlled bymeans of a micrometer screw, whilst that in the other vessels can be con-trolled by a levelling bulb. The pressure in the burette is equated withthat in the balancing tube by means of a drop of liquid in the connectingcapillary. 0*5~-Sulphuric acid is used as washing agent, 0*25~-sodiumhydroxide for the absorption of carbon dioxide, and a mixture of sodiumhydrosulphite (dithionite) (nine parts) and sodium anthraquinone-p-sulphonate (one part), dissolved in 0*25~-sodium hydroxide, for oxygen.The use of indigo-carmine has, however, been recommended instead ofsodium anthraquinone-P-s~lphonate.~~ W.A. Nierenberg and C. Williams 42have constructed an apparatus based on that of Scholander capable ofhandling samples less than 0-6 ml. in volume with an accuracy in the caseof simple binary mixtures of &0-04 %.W. B. Price and L. Woods43 have adapted Krogh’s bubble method44for the analysis of micro-bubbles of gas occurring in glass. The bubbleis collected under glycerol and its diameter measured when i t is held undera microscope slide. It is then exposed to various absorbing solutions suchas cadmium acetate in glycerol for hydrogen sulphide, potassium hydroxidein glycerol for carbon dioxide, aqueous alkaline sodium hydrosulphite(dithionite) for oxygen, ammoniacal cuprous chloride for carbon monoxide,and colloidal palladium in saturated sodium picrate solution for hydrogen.In the case of the glycerol absorbents, the bubble is transferred by means ofa micropipette to a small horizontal glass cylinder immersed in the absorbent,and the cylinder rotated a few times to facilitate contact with the gas.Theaqueous absorbents are contained in a capillary tube along which the gasbubble is allowed to travel. E’or accurate work, however, glycerol and otheralcohols should be used with caution as confining liquids for samples con-taining soluble gases such as carbon dioxide.45Various special methods have also been developed for the analysis ofgas from biological systems.A rapid determination of one constituentof a sample of respiratory gas can be carried out in a very simple apparatusdescribed by P. F. S~holander.~~ A small bulb with microburette attachedis filled with the absorbing solution and connected to a levelling bulb bys9 W. E. Berg, Science, 1946, 104, 575.41 C. D. Stevens, P. van Fossen, J. K. Friedlander, B. J. Rattermann, and M.Inatome, Ind. Eng. Chem. Anal., 1945, 17, 598.42 U.S. Atomic Energy Commission, MDDC-529.43 Analyst, 1944, 69, 117.45 K. A. Kobe and G. E. Mason, Ind. Eng. Chern. Anal., 1946, 18, 78.46 J .Biol. Chem., 1942, 146, 169.40 Rev. Sci. Instr., 1942, 13, 27.44 Xkand. Arch. Physiol., 1908, 20, 279296 AIPN&YTTUAL CHEMISTRY.means of rubber tubing. The rubber tubing is perforated by the end of thesyringe containing the gas sample which can then be injected into theabsorption bulb. Analyses for carbon dioxide and oxygen can be carriedout simultaneously by using duplicate equipment. Techniques for theanalysis of blood gas developed by A. H. Whitely 47 and by P. F. Scholanderand L. Irving48 involve, respectively, a micro-form of the Van Slykeapparatus and a method employing centrifugation for the co&rol of thesample. The Cartesian diver device of J. Needham, V. Rogers, and S. C.Shen49 and the mica-pla.te method of N. G. Heatley, I.Berenblum, andE. Chain 5o for tissue gases do not appear to have received a more generalapplication.Constant-volume methods such as that of Bone and Wheeler have longbeen favoured for macro-scale analyses, and a micro-apparatus based onthis principle has been devised by R. Spen~e.~1 The gas sample, whichmay be either at atmospheric pressure or in a system under reduced pressure,is drawn through a three-way stopcock into a capillary burette attached toa 200-ml. bulb, by displacement of mercury. After closure of the stopcock,the sample is compressed to the 50 cu. mm. mark on the microburette andits pressure observed on a manometer connected to the bulb. It is thendriven through the other arm of the three-way stopcock into a capillaryglass loop previously evacuated by means of a small Topler pump.Theloop consists of a number of segments of capillary tubing connected togetherby waxed joints and contains two simple micro-non-return valves and oneor more small cavities for solid reagents. Oscillation of the mercury abovethe three-way stopcock causes the gas to circulate round the loop. Anyconvenient solid adsorbent can be introduced, and loops for low-temperaturecondensation or for high-temperature combustion may be used. Afterabsorption, which can be followed on the manometer, the mercury is loweredto the bottom of the 500 ml. bulb, the stopcock closed, and the mercuryonce more raised to the burette mark. Since the volume of the capillaryloop is less than 0.1% of that of the bulb, a correction need only be appliedto the second pressure reading when the highest accuracy is desired.W. L.Haden and E. S. Luttrop 52 have described an apparatus of a similar kindfor permanent incorporation in a vacuum system. The mercury bulb andmicroburette are connected, in this case, to a two-way stopcock, the otherarm of which leads to a small bulb below a cone and socket joint. A capillaryside tube with a stopcock leads off from the small bulb. Solid reagents canbe attached to the sealed off tip of the cone which projects into the upperpart of the small bulb. K. W. Saunders and H. A. Taylor 53 modified thisapparatus by introducing a special four-way stopcock and a platinum coilfor combustions, and i t has recently been further modified by C.S. Stover,W. S. Partridge, and W. M. Garrison,54 who have replaced the special stop-47 J . Biol. Chem., 1948,174, 947.48 PTOC. Roy. Soc., 1939, B, 127, 336.s1 J., 1940, 1300.68 J . Chem. Phggica, 1941,9, 686.48 Ibid., 1947, 169, 661.6a I d . Eng. Chem. A d . , 1941., 13,571.64 Analyt. Chem., 1949, 21, 1013.Biochem. J., 1939, 33, 53SPENCE : GAS ANALYSIS CHEMICAL METHODS. 297cock by a standard three-way stopcock and added a second three-way stop-cock leading into the bottom of the large mercury bulb, for admission of thesample or for evacuation. Another variation was introduced by L. K.N a ~ h . ~ ~ I n this case, the 500-ml. bulb is surmounted by a three-waystopcock one of the two upper arms of which leads to a 10-ml. bulb and a10-ml.graduated burette whilst the other is connected to the vacuum lineand to a capillary complex consisting of three absorption lines in parallel.One line contains a platinum wire catalyst for oxidation of hydrogen andcarbon monoxide at 450" and for the oxidation of methane at 950°, thesecond line contains ascarite far the absorption of carbon dioxide, and thethird line contains a trap for low-temperature condensations. Circulationof the gas is controlled by stopcocks and by movement of the mercury inthe bulb. The apparatus is intended for the analysis of samples of theorder of 1 ml. and therefore belongs to the semi-micro-class. L. E. J.Roberts and P. C. Davidge 56 have described a somewhat similar apparatusfor smaller volumes (up to 0.5 ml.) with the microburette below the three-way stopcocks leading to the absorption loops.A very simple arrange-ment is possible, with the elimination of all stopcocks, if carbon monoxideor oxygen is to be determined in binary mixtures with inert gases. Samplesmay be introduced or removed through capillary tubes of greater thanbarometric height leading into the base of the usual mercury bulb. Com-bustions can be carried out over a platinum coil situated between the bulband the microburette, the whole apparatus being arranged similarly to thestandard McLeod gauge.57Variations of the classical high-vacuum technique for the analysis ofsmall amounts of gas obtained, for instance from electric light bulbs, haverecently been described.5* C. E.Ransley separates hydrogen by diffusionthrough a palladium tube at 700", and carbon monoxide and methane aredetermined by combustion over a platinum wire at 500" and 1150°, respec-tively. Kenty and Reuter remove hydrogen and carbon monoxide byignition with oxygen, the excess of oxygen subsequently being determinedby reaction with a heated tungsten filament.Numerous chemical methods for the determination of minor or traceconstituents of gas mixtures have also been reported, as, e.g., the determi-nation of small amounts of hydrogen s ~ l p h i d e , ~ ~ the oxides of sulphur,w theoxides of nitrogen,61 and hydrogen cyanide.62 A particularly valuables5 I d . Eng. Chem. Anal., 1946, 18, 505.66 Atomic Energy Research Establishment Report No. C/R.470.67 F. C . Tompkins and D. M. Young, private communication.8s C. E. Ransley, Analyst, 1947, 72, 504 ; C. Kenty and F. W. Reuter, Rev. Sci. Instr.,1947,18,918 ; see also C. H. Prescott and J. Morrison, Ind. Eng. Chem. Awl., 1939,11,230.6s H. A. J. Pieters, Chem. Weekblud, 1947, 43, 455; E. Field and C. S . Oldbach,Id. Eng. Chem. Awl., 1946, 18, 665.6o E. W. F. Gilham, J. SOC. Ohem. I d . , 1946, 65, 370.61 R. Kieselbach, I d . Eng. Chem. Anal., 1944,16,766; J. F. Flagg and R. Lobene,US. Atomio Energy Commission, MDDC-971.H. F. Taylor, Gr, J., 1947, 252,293298 ANALYTICAL CHEMISTRY.method for the determination of small quantities of carbon monoxide in air,which was originally developed at the Royal Aircraft Establishment,Farnboro~gh,~~ depends on the colour change occurring in a tube of silicagel impregnated with ammonium molybdate and a palladium salt.Themethod, as subsequently modified by the U.S. National Bureau of Standards,wis capable of the detection of less than one part of carbon monoxide in5 x lo8 parts of air in twenty minutes or of physiologically significantquantities in 1-5 minutes.The use of impregnated filter discs for the qualitative detection of gasessuch as arsine and stibine in presence of hydrogen sulphide has been describedby C. L. Wilson,65 and the Feigl-Rossler apparatus for qualitative micro-gas analysis has been improved by R. Belcher.66 Detection and deter-mination of gases evolved in the analysis of carbonates, oxalates, sulphides,sulphites, etc., can be carried out in a simple apparatus due to J.G. Reynolds,67in which a slow stream of air is aspirated over the test solution in a V-shapedtube through a small volume of reagent in a tube inserted in one arm ofthe V. R. S.(ii) Physical Methods.There have been a number of interesting developments in the applicationof physical methods, and several general reviews dealing with the subjecthave appeared. Since the applications of infra-red absorption and of massspectra to gas analysis were last mentioned in the 1946 Report, this seemsto be a good occasion for bringing these subjects up to date and for mention-ing several other useful techniques.give a completereview of this subject with bibliography up to the end of 1948. Since thenthere has been a further general article by M.Boivin,' a description of aninstrument for continuous gas analysis with high-speed response,8 andfurther work on the combination of low-temperature fractional distillationwith mass ~pectrometry.~ C. W. Key10 describes the rapid analysis ofstack gases for totaI sulphur and sulphur dioxide, and the analysis of hydro-carbon gases by a combination of infra-red and mass spectrometry has beendiscussed by D. Milsom, W. R. Jacobi, and A. R. Rescorla.lfThermal Conductivity.-Recent work has consisted of modifications of64 Bnalyt. Chem., 1947, 19, 77.6 6 Metallurgia, 1947, 35, 310.MWS Spectrometry.4, A. Hipple and 141. ShepherdJ. D. Main Smith, R.A.E. Report CH. 324, Aug. 1941.6 5 Analyst, 1940, 65, 407.67 Ibid., 1948, 37, 160.R.H. Miiller, I d . Eng. Chem. Anal., 1941, 13, 667.G. Wagner, Oesterr. Chem.-Ztg., 1941, 44, 176.A. L. G. Rees, Austral. Chem. Imt. J . and Proc., 1947, 14, 23.W. A. Cook, Amer. Id. Hyg. Assoc. Quart., 1947,8,42.H. A. J. Pieters and T. W. van Dam, Het Gas, 1948,68,199.Analyt. Chem., 1949, 21, 32.J. A. Hunter, R. W. Stacy, and F. A. Hitchcock, Rev. Sci. Instr., 149,20,33,331.C . E. Starr, J. S. Anderson, and V. M. Davidson, Analyt. Chem., 1949, 21, 1197.Calif. Oil World, 1949, 42, No. 4, 3, 6 , 7, 25.Analyt. Chem., 1949, 21, 547.Chim. Anal., 1949, 31, 80SMALES : GAS ANALYSIS : PHYSICAL METHODS. 299the previous methods or of adaptations to new problems; thus the thermalconductivity of a gas before and after combustion has been used, e.g., forcombustibles in natural gas after addition of oxygen,12 for oxygen in itsmixture with one or more gases such as CO, CO,, or CH, after addition ofhydrogen,13 and for hydrogen with addition of oxygen. R.H. Cherry l4has discussed general features involved in the determination of water vapourby this method, which was a t one time considered to be rather unpromisingowing to the occurrence of a thermal conductivity maximum in watervapour-air mixtures. As Cherry points out, this only precludes operationin the range 1 2 4 7 % of water vapour by volume and there are manyoccasions involving determination outside this range. Similar maxima arefound for water vapour in nitrogen and oxygen and might be expected incarbon monoxide and possibly in acetylene, ethylene, and ethane, but arenot to be expected in mixtures other than these.R. Edse and P. Harteck l5have pointed out the advantages of thermal conductivity over gas densityafter using the desorption technique; smaller quantities of gas and activecharcoal are necessary and the gas is recoverable; they illustrate this inthe analysis of hydrogen-deuterium and other isotope mixtures. C . A.Hansen,lS H. A. J. Pieters,l7 F. Lieneweg,ls and C. C. Minter have alldiscussed the industrial applications, and the last author 2o has also dis-cussed the effects of pressure changes on thermal conductivity. W. J.Clark 21 suggests a device for automatic compensation for such pressurechanges. The use of thermal conductivity for analysis of gases associatedwith internal-combustion engines has been the theme of several patents:,and the application to fluorine-nitrogen mixtures 23 is another example ofthe wartime emergence of fluorine as an industrial gas.Heat of Combustion or Reaction.-The heat of reaction when a gasburns a t a filament or in the presence of a catalyst has frequently been usedfor the determination of combustible gases, e.g., exhaust gases from internal-combustion engines,,, oxygen in flue 25 and other gases 26 after addition ofhydrogen, and low concentrations of carbon monoxide in air.27Electrolytic Conductance after Absorption.-The main application ofthis method is 'in the determination of carbon dioxide after absorption inl2 R.Weber, U.S.P. 2,399,96517.5.46.l3 G.A. Perley and J. B. Godshalk, B.P. 567,974112.3.45.l4 Analyt. Chem., 1948, 20, 1033.l5 Angew. Chem., 1939, 52, 32; 1940, 53,210.l6 @en. Elect. Rev., 1940, 43, 166.lE Arch. tech. Messen., 1942,138, T 125; 1943, 140, T 17.l9 J . Chem. Educ., 1946, 23, 237.2o Analyt. Chem., 1947,19, 464.22 D. E. Olshevsky, U.S.P. 2,154,862118.4.39; W. J. Willenborg, U.S.P. 2,255,551123 E. Staple and E. R. Grilly, U.S. Atomic Energy Commission, MDDC-1565,24 B. Miller, U.S.P. 2,152,439/28.3.39; 2,219,540/29.10.40.25 A. P. Sullivan, U.S.P. 2,310,472/9.2.43.26 G. Cohn, Analyt. Chem., 1947, 19, 832.27 M. Katz and J. Katzman, Canad. J . Res., 1948,26, F, 318.l7 Chem. Weekblad, 1940, 37, 316.2 1 U.S.P. 2,472,64517.6.49.9.9.41 ; H. Laub, U.S.P.2,256,395/16.9.41300 ANBLYTICAL CHEMISTRY.barium hydroxide solution, either directly or indirectly as in the deter-mination of hydrocarbon gases after combustion with oxygen 28 or for watervapour and oxygen in gases containing no other oxygen compounds, bypassing through charcoal a t lOOO", giving carbon monoxide which is thenpassed over iodine pent~xide.~~ An automatic apparatus for sulphurdioxide has also been described.30 An interesting method for the deter-mination of water vapour in gases has been described by E. R. Weaver andR. Riley31 depending on the difference in conductivity of a thin film ofphosphoric acid with alteration in the water vapour content of gas flowingover it. The extension to the determination of oxygen in combustiblegases after combustion is suggested.Ionization Potential.-Unlike many of the other physical methods, theionization potential of a gas is an almost specific property and a number ofpatents using this principle have been listed.32Polarography ebnd Amperometric Titration.-This method is an obviousone for the determination of oxygen in industrial gases, and P.Beckmann 33has described continuously indicating polarographic method for oxygencontained in the gas obtained during the carbonization of oil shale.D. W. E. Axford and T. M. Sugden 34 make use of amperometric titrationfor the determination of sulphur trioxide in its mixtures with dioxide ; afterabsorption of the gases in sodium hydroxide solution, the sulphur dioxideis removed, after acidification, by a stream of nitrogen, the remainingsulphate being titrated amperometrically with lead nitrate solution.Magnetic Susceptibility.--H.Rein 35 has described a continuous methodfor the determination of oxygen depending on the decrease of thermalconductivity of oxygen in a magnetic field. The arrangement is similarto the usual thermal conductivity method in that the gas stream is dividedinto two channels each with a heated platinum wire connected in a Wheat-stone bridge arrangement. The extent of disequilibrium on application ofa strong magnetic field to one of the channels is a memure of the oxygencontent. Applications have also been discussed by L. Pauling36 andN. S ~ h w a r z . ~ ~Emission Spectr~sco~y.-As W. F. Meggers says in a recent review,38(' recent attempts to detect and determine gases spectrographically aresolely represented by experiments with halogens excited either by ultra28 G.I;. Hassler, U.S.P. 2,230,59314.2.41; Csn. P. 395,346118.3.41; B.P. 537,486138 N. Shurmovskaya and L. Kupriyanov&, Zhur. Anal. K h h . , 1948, 3, 41.80 M. D. Thomas, J. 0. Ivie, and T. C. Fitt, Ind. Eng. Chem. Anal., 1946,18,383.81 J . Res. Nat. Bur. Stand., 1948, 40, 169.92 W. Jaeger, D.R.-P. 696,05418.8.40;38 Chem. and Id., 1948, 791.86 U.S.P. 2,416,344125.2.67.87 Applied Sci. Research, 1947, A, I, 47.88 Analyt. Chm., lM9, 21, 29.24.6.41 ; Dutch P. 52,836115.7.42,A. P. Solovov, Russ. P. 67,531131.7.40;L. T. Winkler, U.S.P. 2,387,550/23.10.45.J., 1946, 901.D.R.-P.742,690121.10.43; Zen&., 1940, I, 2204SMALES: GAS ABNALYWS: PHYSICAL METHODS. 301high frequency electric fields 39 or in hollow cathode discharges.” Thedetermination of as little as 0.01 fig. of fluorine and 0.2 pg. of chlorine iscited in the latter paper. Another method for fluorine, vix., evolution assilicon tetrafluoride followed by spectrographic determination of the silicon,has been described by R. W. Spence:41 1 pg. of fluorine was the lower limitfor determination although 0.01 pg. was detected ; the greatest difficultyin attaining such sensitivity was the reagent blank.Raman spectroscopy has been used but little in gas analysis.Absorption Spectroscopy.-(a) X-Ray. Only within recent years hasit become possible to measure X-ray absorption precisely and convenientlyand it is likely that it will assume increasing importance.Preliminarystudies using a photomultiplier tube as detector with a polychromaticX-ray beam have been reported on hydrogen, methane, air, oxygen, andmethyl and a general review by H. A. Liebhafsky43 should benoted.Further applications of this technique,usually with simple filter instruments, fall into two general types : absorptionof light (i) by the gas itself 44 (e.g., nitrogen peroxide) or after reaction toform another gas (e.g., oxygen by reaction with nitric fluorine byreaction with sodium bromide 46) or (ii) after reaction of the gas in solutionto give a light-absorbing product (e.g., sulphur dioxide by reduction ofchromate!’ oxygen by reaction with reduced sodium anthraquinone-p-sulphonate) .48The appearance of the General Electric Company’s mercury-vapourdetector, and the extension of this principle to a general purpose unit forlight-absorbing vapours 49 should be noted.(c) Infra-red.The outstanding advance in this connection has beenthe development of industrial gas analyzers using no dispersing system.These are very sensitive and capable of detecting selectively a few partsper million of many gases or vapours which have strong absorption in theinfra-red.H. W. Thompson 50 has summarized the basic features of these instru-(b) ‘Visible and uttra-uiokt.9D A. Gatterer and V. Frodl, Richerche Spettroscop., 1946, 1, 201; Spectrochim,4O J. R. McNally, G. R. Harrison, and E.Rowe, J . Opt. SOC. Amer., 1947, 3’9, 93.4l U.S. Atomic Energy Commission, MDDC-310.42 E. H. Winslow, H. M. Smith, H. E. Tanis, and H. A. Liebhafsky, Analyt. Chem.,4s Ibid., 1949, 21, 17.44 I. N. Kuzminyka, E. Ya-Turkan, and E. I. Savinkova, Zauod. Lab., 1941, 10,46 D. G. C. Eare, U.S.P. 2,389,046/13.11,45.46 L. K. Nash, Analyt. Chem., 1949, 21, 980.47 P. V. Moskalev, Lab. Prakt. (U.S.S.R.), 1940,15, 26.48 L. J. Brady, Analyt. Chem., 1948,20,1033.4e M. B. Jacobs, “Analytical Chemistry of Industrial Poisons, Hazards and6o Ann. Repwts, 1945, 42, 16,Acta, 1948, 3, 214.1947, 19, 866.139; R. H. Parker and J. K. Dixon, U.S.P. 2,417,321/11.3.47.Solvents,” Interscience Publishers Inc., New York, 1941, p. 375302 ANALYTICAL CBEMISTRY.ments, which in general may be classed either as the positive 51 or thenegative filter type, and instruments of both types are now availablecommercially.R. D. Miller and M. B. Russell 53 have suggested the name" autodetector " for the positive filter type and describe a simple laboratory-constructed analyzer for minimising drift, one of the major difficulties ofthese gas analyzers. They use a drop of fluid in a capillary for observingpressure-volume changes in the detector cell and measure its position byuse of a photoelectric position indicator effectively amplifying its motionabout 200 times, enabling changes of less than 10 p.p.m. in the range0-300 p.p.m. of carbon dioxide in air to be detected.H. W. Deinum 54 has described the use of the Baird Associates infra-red gas analyzer for CO,, CH,, CO, H,O, c6H6, and C,H,*CH,, and a com-parison has been made of the infra-red and the iodine pentoxide methodsfor the determination of carbon monoxide in 1lline-damp.5~ A review givingnumerous references to infra-red analysis for specific gases has been givenby R.B. Barnes and R. C. Gore,56 and more recently the adaptation of thePerkin Elmer instrument for continuous determination of six differentcomponents has been de~cribed.~'(d) Micro-wave. Largely as a result of wartime developments, work inthe micro-wave region, Le., 0.3-20 cm.-l, has become a practical possibility.Just as the electronic spectra of molecules occur largely in the visible andultra-violet, and vibrational spectra in the infra-red, so the rotational-energy spectra are observed most conveniently in this micro-wave region.As yet little analytical work has been carried out, but a considerable numberof laboratories, particularly in the United States, are equipped with micro-wave spectrographs for the study of molecular structure and the spins andmoments of nuclei.However, the technique is particularly suitable for,and in fact at present is limited to, gas analysis, although of course moleculeswith no dipole moment, such as carbon dioxide and methane, cannot bedetected and those with dipole moments of less than 0.1 Debye unit offerserious difficulties. The particular attraction of this region lies in the factthat the resolution available is so great that interferences from overlappingspectra are almost completely eliminated.Equipment for micro-wave spectro-scopy is still in an early stage of development ; nevertheless, it seems to theReporter that the industrial analyst should certainly consider its possibilitiesand create the demand for commercial instruments. One useful referencemay be given as a starting point for further reading.58Fractional Distillation.-This is one of the most useful physical methodsavailable to the gas analyst, particularly where complex mixtures of hydro-carbons are concerned. There have been a number of improvements in5 1 K. F. Luft, 2. tech. Physik, 1943, 24, 97; F. I. Callisin, Nature, 1947, 159, 167.62 W. 8. Baird, J. Opt. SOC. Amer., 1945, 35, 7998.53 A d y t . Chem., 1949, 21, 773.55 A.Jager and W. Grebe, Gliickauf, 1949,85, 294.56 Analyt. Chem., 1949,21, 7.5 7 J. U. White, MI. D. Liston, and R. G. Shard, ibid., p. 1156.68 B. P. Dailey, ibid., p. 540.54 Rec. Trav. chim., 1948, 67, 725SMALES : GAS ANALYSIS : PHYSICAL METHODS. 303apparatus, particularly in new types of packing for the fractionation columnand there has been a recognition of the limitations of the distillation methodof analysis with a tendency towards combination of this process with variousphysical, particularly infra-red and mass spectroscopy: and chemicalmethods. A. Rose 59 has fully reviewed this subject recently.Acoustical Methods.-The acoustical gas analyzer is based on theprinciple that the velocity of sound in a gas is a function of the averagemolecular weight of the gas.The apparatus described by C. E. Crouthamel and H. Diehl 6o is typicaland uses an audio-frequency oscillator to generate a signal operating a smallspeaker placed at one end of a brass tube through which the gas sampleflows. A sensitive microphone at the opposite end of the tube gives amaximum or minimum signal depending on the resonance conditions of thetube, which in turn are related to the average molecular weight of the gasby the relationship f = kyT/2M, where f is the natural frequency of theresonator, k. is a constant depending on the dimensions of the resonator,y = c3-/cv, i.e., ratio of specific heats of the gas mixture at constant pressureand volume, T is the absolute temperature, and 2M the molecular weight.Thus if T is maintained constant, the natural frequency is a function primarilyof the average molecular weight. The method is useful for effectively binarymixtures and has been found to work well for hydrogen in a mixture withair or the common gases, and for carbon dioxide in air, but is less sensitivefor methane, oxygen, and ethylene, and insensitive for carbon monoxidein air. The application to mixtures of helium, oxygen, and nitrogen hasalso been described.61The optical acoustical method described by M. Vengerov,62 dependingon the absorption of light in gases, is similar in principle to the infra-redgas analysers previously mentioned.Gas Density.-A critical study of eleven commercial instruments fordetermining specific gravities of gases has been made by the National Bureauof standard^.^^Interferometry.-A few further applications of this well-known methodcan be noted; 1%. A. Patty 64 has determined organic vapours in gases,A. J. Anthony 65 gives a description of the technique of gas analysis usingthe Zeiss laboratory interferometer, and H. Dierkesmann 66 describes theexact analysis of oxygen-nitrogen mixtures.Diff usion.-This method is particularly applicable to hydrogen and onepaper in particular 67 should be noted. This describes a universal gaso-61 W. B. Dublin, W. M. Boothby, and M. D, Marvin, Science, 1939, 90, 399; Proc.Stag Meetings Mayo Clinic, 1940, 15, 412.62 Compt. rend. Acad. Sci. U.R.S.S., 1938, 19, 687; 1946, 51, 195; Nature, 1946,158, 28; Zavod. Lab., 1947, 13, 426.6s Smith, Eiseman, and Creitz, U.S. Bur. Stand., Misc. pub. M. 177 (1947).64 J . Ind. Hyg. Toxicol., 1939, 21, 469.65 2. ges. exptl. Med., 1939,106, 561.6 7 L. P. Pepkowitz and E. R. Proud, Analyt. Chem., 1949, 21, 1000.Analyt. Chem., 1949, 21, 81. 6o Ibid., 1948, 20, 515.66 Ibid., 1940, 107, 736304 ANALYTICAL CHEMISTRY.metric micro-method for the determination of hydrogen in organic, inorganic,and metallo-organic compounds or low-melting metals. Reduction bysodium or magnesium metal is carried out in a sea.led iron capsule throughthe walls of which the evolved hydrogen diffuses into a vacuum system.Miscellaneous.-Miscellaneous work on several other techniques hasbeen described, e.g., analysis by electron scattering,68 by vapour pressure,69€or hydrocarbons by adsorption on active charcoal, 70 followed by fractionaldesorption; for organic sulphur compounds by adsorption on silica gel 71followed by hydrogenation to hydrogen sulphide and colorimetric deter-mination of this; and there is an important section concerning the analysisof gases evolved from metals by vacuum extraction and fusion.72A. A. S.G. INGRAM.H. M. N. H. IRVING.A. A. SMALES.R. SPENCE.W. A. WATERS.L. A. WOODWARD.S. S. West, Ceophy&ics, 1943, 8, 404; J. Hillier, U.S.P. 2,468,261/26.4.41.@@ J. Smittenberg, Rec. Trau. chim., 1948, 67, 703.?* K. Bratzler, Oel u. Kohle, 1943, 39, 953; N. C. Turner, U.S.P. 2,398,817-8/7L J. K. Fog0 and M. Popowsky, Analyt. Chem., 1949, 21, 773.?* D. Lipkin and M. L. Perlman, U.S. Atomic Energy Commission, MDDC-294;C. N. Rice, MDDC-356; L. Brewer, MDDC-366; R. L. Seifert, L. 0. Gilpatrick,T. E. Phipps, and 0. C. Simpson, AECD-2331; Holm, J. Res. Nut. Bur. Stand.,1941, 28, 245; T. Somsiya, J . SOC. Chem. In&. Japan, 1942, 45, 183; G. W. Keilholtzand M. J. Bergin, Instruments, 1949, 22, 320; P. Klinger, Arch. Eisenhiittenw., 1949,20, 151 ; I€. F. Beeghly, Analyt. Chem., 1949,21, 241.23.4.46

ISSN:0365-6217    

DOI:10.1039/AR9494600268

出版商:RSC    

年代:1949

数据来源: RSC

摘要:

INDEX OF AUTHORS' NAMES.Abrahams, S, C., 63.Abrams, R., 100.Achmatowicz, O., 208.Ackermann, H., 274.Ackermann, W. W., 185.Acree, F., jun., 166Adams, R., 122, 141, 142,Adamstone, F. B., 252.Addamiano, A., 85.Addison, C. C., 30, 103.Adell, B., 27.Adkins, H., 140, 147.Ady, P., 42.Aebi, F., 72, 74.Afffezweig, N., 195.Ageev, N. V., 66Aggarwal, S. L., 38, 40.Aharoni, J., 37.Ahl, A,, 202.Ahmad, K., 165.Ahrland, S., 99.Akalan, (Mlle.) S., 105,Alameda, J. M., 40.Albertson, N. F., 152, 185,187, 188, 189, 193.Aldrich, L. T., 8, 89.Alexander, E. R., 145, 151.Alexander, K. M., 105.Alexander, M., 17.Alicino, J. F., 284.Allan, J. E., 138.Allemam, T., 204Allen, C. F. H., 142.Alm, R. M., 145, 146,Alpher, R. A,, 87.Altieri, V.J., 291.Aluise, V. A., 284.Ambrose, E. J., 227, 228.Andersen, V. S., 106.Anderson, A. R., 292.Anderson, D., 38.Anderson, E. C., 10.Anderson, G. C., 237.Anderson, H. H., I l l .Anderson, J. S., 25, 80, 98,Anderson, R. J., 157, 160,Andresen, C. A,, 107.Andrews, J. P., 25.Andrews, G. A., 232.Andrews, L. J., 129, 120,Anelli, J., 283.Anet, E., 196.Angier, R. B., 230.Angla, B., 156.Anglaret, P., 158.198.298.161, 162.Angus, W. R., 38, 39, 103.Anthony, A. J., 303.Aramburu, T., 232, 240.Archer, S., 151, 153, 185,187, 188, 189, 193, 194.Arcus, C. L., 155, 165.Ardenne, M. von., 290.Arens, J. F., 141, 169, 170,Argersinger, W. J., 90.Armstrong, B. E., 231.Armstrong, M. D., 188.Arnold, R. C., 146.Arnold, R. T., 155.Arnold, W., 196.Artemov, I.S., 28.Asinger, F., 157, 158.Asperger, W., 108.Astakhov, K. V., 19, 21.Astbury, W. T., 211, 212,220, 226, 227.Aston, J. G., 9, 18.Atkinson, R. O., 187.Attenburrow, J., 188.Auerbach, I., 142.Augur, M. V., 157.Avskian, S., 194.Axford, D. W. E., 18, 28,Aynsley, E. E., 111.Baccsredda, M., 20.Bach, R. O., 274.Bacharach, A. L., 180.Bachmann, W. E., 142.Backer, H. J., 157.Baddar, F. G., 38.Baddiley, J., 187.Badin, E. J., 32, 95.Baenziger, N. C., 68.Baer, E., 167, 168.Bagard, P., 155.Baguley, D. M. S., 41.Bailar, J. C., 91.Bailey, A. S., 201, 207, 208.Bailey, J. L., 195.Bailey, K., 211.Bailey, M., 80.Bain, J. A., 234.Baird, W. S., 302.Baizer, M. M., 135.Baker, J.W., 151.Baker, W. O., 20.Balaba, T. A,, 257.Baldwin, A. R., 166.Baldwin, F. H., 149.Baldwin, R. R., 292, 293.Baldwin, S., 112.171, 172, 249.300.305Bale, W. I., 191.Balfe, M. P., 119, 129.Ball, S., 171, 183, 255, 262,Ballentine, R., 283.Ballou, N. E., 96.Bamford, C. H., 292, 293.Band, W., 8, 89.Banerjea, P., 143.Banerjee, R. P., 41.Bangerter, F., 274.Banks, A. A,, 110.Banks, C. V., 110, 271, 272.Bannerot, R. A., 164.Bannister, F. A., 77.Banns, M. D., 95.Baranaev, M. K., 26.Barb, W. G., 106.Barber, H. J., 194.Bardeen, J., 13, 14, 44.Barer, R., 235.Barnes, R. B., 302.Barnes, R. H., 237.Barrer, R. M., 9.Barriol, J., 17.Barrow, R. F., 109.Barry, (3. T., 10.Barry, R. H., 192.Bartlett, P. D., 115, 117,Barton, D.H. R., 14, 119.Bartram, K., 171.Barua, R. K., 180, 252.Baryshnikova, A. N., 135.Basch, H., 285.Basford, P. R., 28.Bass, E., 284.Bassett, H., 58, 96.BassiBre, M., 23.Bastiansen, O., 16.Bateman, L., 31, 32.Bateman, L. C., 115.Battersby, A. R., 202.Baudart, P., 164, 165, 166.Baudler, M., 107.Bauer, E:, 20, 163.Bauer, H., 30, 107.Bauer, S. H., 12, 103.Bauer, S. T., 165, 166.Baughan, E. C., 18, 116.Baumann, C. A,, 246, 256,Baumgarten, E., 154.Baumgarten, P., 95.Bawden, F. C., 21 1.Baxendale, J. H., 106.Baxter, J. G., 168, 169, 174,263, 266.125.257, 258.175, 252INDEX OF AUTHORS’ NAMES.Bayer, O., 150.Baylis, N. E., 110.Bayliss, N. S., 15.Bazett, H. C., 292.Beachell, H. C., 97.Beamer, W.H., 100.Beamish, F. E., 269, 270.Bearden, J. A., 49.Beck, G., 271, 275.Becker, W. W., 282, 284.Beckman, A. O., 293.Beckmann, P., 300.Bedoit, -W. C., 140.Bedwell, M. E., 38.Beeck, O., 10.Beeghly, H. F., 304.Beeman, W. W., 49.Begbie, G. H., 23.Behringer, H., 189.Beiler, J. M., 233.-Beicher, R., 273, 281, 298.Bell, F., 155.Bell, G. C., 289.Bell, R. P., 12, 17, 30, 68.Belt, M., 238.BBnard, J., 27, 111.Bender, P., 279.Benesi, H. A., 110, 139.Benest, K. A., 13.Bengen, F., 156.Bennett, A., 282.Bennett, G. M., 131, 132,Bennett;, L. L., 143.Benton, F. L., 151.Benz, J., 142, 175, 177.Berck, 243.Berenblum, I., 296.Berg, C. P., 190.Berg, W. E., 295.Bergel, F., 200.Berger, A., 226.Berger, L.B., 293.Berger, M. F., 192.Bergin, Xf. J., 304.Berglund, U., 30.Bargmann, M., 122, 186,Bergsma, F., 8.Berk, L., 243.Berliner, E., 139.Berliner, F., 139.Bernal, J. D., 33, 64, 86.Bernhard, F., 290.Berlinguet, L., 193.Bernstein, H. J., 18.Berthelot, D., 94.Berthier, G., 15, 17, 18.Berthier, P., 36.Bessey, 0. A., 258.Besson, J., 93, 103.Beste, G. W., 115.Bethe, H., 48, 87.Bethell, F. H., 232,240,241,Betts, R. EI., 99.134.189, 212, 213, 220.243.Bevan, D. J. M., 25.Beverue, A., 245.Beyler, R. E., 148, 199.Bhatnagar, S. S., 36, 42.Bhattacharyya, S. K., 16.Bick, I. R. C., 201.Bickel, A. F., €98.Bickoff, E. M., 245.Biedermann, M. M., 12, 23.Biedermann, W., 274.Bielig, H.-J., 247.Bigeleisen, J., 277.Bigich, I.S., 30.Bij, J. R. van der, 157.Bijvoet, J. X I . , 21, 58, 206.Billeter, 3. R., 154.Billica, H. R., 140.Billimoria, J. D., 186.Billmann, J. H., 195.Binkley, S. B., 142.Binnie, W. P., 23, 63.Birch, A. J., 31, 146, 163.Birchenall, G. E., 11.Bircumshaw, L. L., 102.Bird, H. R., 235, 236.Bird, 0. D., 232, 233, 234.Birks, J., 26.Bizouard, M., 11.Bjerrum, N., 92.Blacet, F. A., 31.Black, D. M., 180.Black, S., 230.Blair, C. M., 292.Blass, J., 185.Bleaney, R., 41.Blewett, M., 231.Blicke, F. F., 151.Bliss, A. F., 183, 261, 262,266.Blizzard, R. H., 145.Bloch, 43.Bloch, E., 169.Bloch, R. J., 212, 214.Blocher, J. M., 32.Block, R. J., 187.Blodgett, E., 274.Bloem, G., 139.Blomquist, A. T., 149.Bloom, H., 29.Blount, E.R., 14.Bobtelsky, M., 112.Bockemiiller, W., 155,Bockris, J. O’M., 29, 31.Bode, H., 104.Bohme, H., 125.Boekelheide, V., 142, 148.Boerger, E., 94.Boese, A. B., 149.Bottcher, C. J., 21.Bogdanow, I. F., 37.Bohlmann, F., 141, 142,Bohlmam, M., 141, 142,Boivin, M., 298.Bokhoven, C., 58, 206.171.171.BoIIing, D., 214.Bolz, A., 16, 95.Bond, H. W., 194.Bondhus, F. J., 139.Bongert, A,, 159.Bonner, J., 244.Boon, J. W., 71.Boon, 0. R., 194.Boord, C. E., 141, 158.Booth, A. D., 58, 61, 62.Booth, E., 189.Boothby, W. M., 303.Boothe, J. H., 230.Borrows, E. T., 192.Borsook, H., 191.Borurn, 0. H., 143, 188.Boscardin, B., 107.Bosshardt, D. K., 237, 238.Bouissihres, G., 98.Bourgeois, R. C., 192.Bourne, E.J., 156.Boutaric, A., 36.Bouveault, L., 159.Bowden, J. N., 155.Bowers, R. E., 248.Bowman, R. E., 159, 164.Boyd, G. E., 285, 288, 289.Boyer, R. Q., 269.Bracco, M., 257.Bradbury, R. B., 285.Bradfield, A. E., 138, 139.Bradley, A. J., 50.Bradley, R. S., 26.Brady, L. J., 301.Brand, E., 214,216,217.Brand, J. C. D., 131, 132.Brandela, M., 105.Brandenberg, R. O., 232.Brandt, W. W., 272.Bratzler, K., 304.Braude, E.A., 31,121,125,126, 128, 130.Braude, R., 237.Braun, F., 196.Braun, W. G., 276, 278.Breckenridge, J. G., 91Breger, A. K., 19.Brehm, W. J., 208.Breiger, H., 147.Brenner, M., 186.Breslow, D. S., 153, 154.Bretscher, E., 181.Breusch, F. L., 159.Brewer, L., 71, 304.Brewster, J. H., 152.Brickson, W.L., 237.Brickwedde, F, G., 9.Briggs, D. R., 225.Briggs, G. M., 230.Briggs, L. H., 207.Bright, N. F. H., 11.Brill, R., 66.Brillouin, 43.Briner, E., 109.Brink, C., 74, 105.Brink, N. G., 155,234, 235MDEX OF AUTHORS' NAMES. 307Brintzinger, H., 96, 105.Broadley, J. S., 83, 103.Brockman, J. A., 210.Broda, E. E., 261, 263.Brode, W. R., 165.Broja, G., 102.Bromley, L. A., 71.Brook, A. J., 238.Brooker, L. G., 14.Brooks, F. R., 293.Broomhead, J., 85.Brosset, C., 75.Brown, C. J., 82, 101, 225,Brown, G. L., 29.Brown, H., 90, 289.Brown, H. C., 116.Brown, J. B., 165.Brown, J. H., 104.Brown, R. A., 232, 233.Brown, R. D., 16.Brown, W. G., 141, 142,Brownell, W. B., 110.Brownlee, G., 161.Briick, R., 112.Briickner, V., 226.Briill, L., 276.Bruggen, J.T. von, 258.Brusset, H., 100.Bryson, A., 16.Buc, S. R., 187.Buchheit, P., 95.Buckles, R. E., 122.Buckley, H. E., 22.Biichi, G., 178.Buerger, M. J., 59, 71, 76,Bull, H. B., 224.Bumpus, F. M., 165.Bunn, C. W., 59.Bunton, C. A., 135.Burbank, R. D., 22, 73.Burg, A. B., 95.Burgus, W. H., 87.Burke, S. S., 294.Burness, D. M., 125.Burnop, V. C. E., 189.Burriel, F., 273.Bursa, F., 218, 226.Burstein, R., 34.Burton, C. J., 20.Burton, H., 126, 127.Burtt, B. P., 11.Buscarons, F., 271.Butkow, K., 9.Butler, E. J., 271.Butler, J. A. V., 223.Buyze, H. G., 233, 242.By& J., 93.Byerly, W., 39.Byers, J. R., 142.Byrd, W. M., 142.Bystrom, A., 58, 73.Bystrom, A.M., 73.227.146.77.Buu-Ho'~, N. P., 163.Cady, G. H., 12, 110.Cagle, F. W., 273.Cagniant, P., 163.Cahmann, H. J., 142, 169,Calderbank, K. E., 19.Caldirola, P., 9.Caley, E. R., 270.Callisin, F. I., 302.Cama, H, R., 257.Camarcat, M., 98.Camp, D. B., 191.Campaigne, E., 192.Campbell, A., 155.Campbell, A. D., 148, 164.Campbell, K. N., 147.Campbell, M. A., 174, 176.Canadell, J. M., 256.Cannan, R. K., 216, 218.Cannon, W. F., 13.Cappelen, P. T., 102.Caravella, M., 165.Cardwell, H. M. E., 152.Carhart, H. W., 140, 145.Carlisle, C. H., 33.Carmack, M., 135.CarpBni, G., 96.Carpenter, K. J., 241.Carr, E. M., 14.CarriBre, E., 102.Carroll, M. F., 30, 120.Carson, A. S., 18.Carter, C. L., 148, 163, 164.Carter, H.E., 188.Carter, P. G., 16.Carter, P. W., 247.Carter, R. L., 13.Carter, W. C., 21.Cary, C. A., 236.Casanova, R., 142.Cason, J., 159, 160, 162.Castellan, G. W., 90.Castille, A., 166.Castle, W. B., 240.Caswell, M. C., 237.Catch, J. R., 184.Catchpole, A. G., 128, 130.Caunt, A. D., 109.Cawley, S. D., 168, 169,175, 180, 181, 184, 252.Chadwick, J., 286.Chaikin, S. W., 146.Chain, E., 114, 296.Chakravarti, R. N., 141,Chalmers, J. R., 192.Chalvet, O., 15, 104.Chambers, D. C., 217.Chambers, J. S., 191.Chand, R., 283.Chanley, J. D., 142, 178,Chanson, P., 87.Chapelle, J., 17.Charon, E., 130.Charron, F., 20.172.207, 208.179.Chatterjee, A,, 245.Chaudron, G., 24, 111.Chauvin, R., 248.Chedin, J., 104, 131.Cheesman, G.W. H., 140,173, 179.Chen, C., 167.Chenery, E. M., 273.Cheney, L. C., 142.Cheney, R. K., 99.Cherry, R. H., 299.Chevenard, P., 269.Chibnall, A. C., 213, 214,218, 229.Chien, J., 279.Chih, C. M., 145.Chivers, J. E., 283.Chodorow, M. I., 44.Chou, T. Q., 210.Christian, J. W., 48.Christiansen, J. A., 294.Chulski, T., 105.Chuoke, R. L., 14.Church, M. C., 115.Cirilli, V., 35.Claesson, S., 83, 103.Claringbull, G. F., 77.Clark, D. M., 155.Clarke, H. T., 114.Clark, R. O., 280, 282.Clark, W. J., 299.Clarke, H. M., 289.Clarke, J. W., 269.Classen, F., 93.Claude, A. G., 8.Claude, G., 8.Clayton, J. C., 192.Clemo, G. R., 143, 199, 204,Clews, C. J. B., 63.Clifford, A. F., 97.Cloke, J.B., 285.Clough, F. B., 252.Clusius, K., 12.Cochran, W., 61, 62, 63.Cockburn, W. F., 198.Coetzee, H. K., 251.Cohen, S. G., 122.Cohen, W. D., 167.Cohn, E. J., 224.Cohn, G., 27, 299.Cohn, W. E., 290.Cole, A. R. H., 235.Cole, W., 141.Cole, W. F., 78.Coleman, D., 225, 227.Coleman, P. D., 279.Coles, D. K., 13.Coles, M., 231.Coley, J. R., 105.Collie, C. H., 11.Collins, C. B., 106.Collins, F. D., 261, 263,Collins, R. L., 73.Colson, A. F., 281, 282.208, 210.264308 INDIX 03 A ~ O R S ~ NAMES.Conger, T. W., 169, 249.Connick, R. E., 97, 100,Consden, R., 185, 220.Cook, A. H., 114, 184, 186,Cook, J. W., 148.Cook, L. G., 87.Cook, M. A., 28.Cook, W. A,, 298.Cooper, K. A., 117.Copenhauer, J. E., 160.Copp, J.L., 9.Corbett, R. E., 168.Corbin, N., 17.Cordike, G. F., 13.Cornwall, B. C., 175.Corwin, J. F., 9.Coryell, C. D., 87, 112.Cosby, J. N., 156.Costain, W., 83.Cotton, F. S., 292.Cottrell, A. H., 43.Cottrell, T. L., 19, 66.Couch, 5. F., 200.Coulson, C. A,, 16.Courty, C., 37.Couture, L., 12.Cowdrey, W. A., 122, 135,Cox, E. G., 64, 83, 103.Cox, J. M., 143.Craig, A,, 269.Craig, D. P., 16.Craig, L. C., 10.Craig, R., 269.Cramer, R., 170.Crandall, H. W., 99.Crane, R. A., 293.Cravens, W. W., 236, 237.Crawford, B. L., 112, 277.Crawford, V. A,, 28.Creitz, 303.Cremer, E., 93.Crickenburger, A., 284.Cristensen, L. K., 225.Cristol, S . J., 152, 153, 185,Croatto, V., 107.Crombie, L., 166.Cross, L. C., 247.Crouch, G.E., 21.Crouthamel, C. E., 110,303.Crow, W. D., 210.Crowfoot, D., 58, 224.Cruickshank, D. W. K., 62,Cruikshank, J. H., 38.Cummerow, R. L., 40, 41.Cunningham, B. B., 100,Curme, H. G., 33.Currie, B. T., 224.a s t e r , J. H., 213, 214.Cutforth, H. C., 38, 39.Cuthbertson, W. F. J., 236,102.194.192.63.269.238,cymerma& J., 173, 175.Dailey, B. P., 802.Dalgliesh, C. E., 226.Dallinga, G., 105.Dalmon, R., 30. *Dalvi, P. D., 263.Dam, J. W., 291.Dam, T. W. van, 298.Danielson, G. C., 22.Darby, W. J., 194, 230,Darmon, 8. E., 226, 227.Darwent, B. de B., 32.Dauben, H. J., 147.Daubert, B. F., 142, 167.Daudel, P., 87, 104, 107.Daudel, R., 87.Daunt, J. G., 8, 89.David, S., 162.Davidge, P. C., 297.Davidson, L.S. P., 241.Davidson, N., 13, 96, 100,Davidson, V. M., 298.Davidson, W. L., 285, 290.Davies, A. W., 252.Davies, D. D., 109, 113.Davies, D. S., 135.Davies, T. H., 87.Davis, A. C., 194.Davis, J. W., 126.Davis, M. M., 273.Davis, R. T., 28.Davis, S., 33.Davis, W. D., 95.Dawson, I. M., 23.Dawson, R. F., 198.Day, H. G., 192, 256.Day, J. N. E., 119.Day, P. L., 230, 231, 232.Dean, L. B., 18.Deasy, C. L., 191.De Boer, F., 73.De Bretteville, A., 22.Decombe, J., 283.De Decker, H. C. J., 80.Degering, E. F., 191.De Grande, E., 8.De Groot, S. R., 8, 12, 23.De Heer, J., 15.Deinum, H. W., 291, 302.De Klerk, D., 40.Dekker, C. A,, 186.De La Huerga, J., 231.De La Mare, P. B. D., 128,De La Tullaye, R., 269.DeIaune, R.H., 270.Delgery, I., 40.Della Monica, E. S., 213,Delluva, A. M., 191.Delwaulle, M.-L., 277, 278.De Meillon, B., 231.Demidenko, 8. G., 292.231.105.138.214.Denbigh, K. G., 8.Dennison, D. M., 13.Dent, S. G., 14.Denton, C. A., 236.Derbyshire, D. H., 110.Derfer, J. M., 141.Desrivieres, J. E., 261.Dessens, H., 28.De Toledo, P. S., 87.Deuel, H. J., 245, 246, 255,Deuel, H. J., jun., 245, 246,Deulofeu, V., 194.Deuticke, F., 34.Deutsch, H. F., 234.De Vos, P. J. G., 60.Dewar, A. D., 256.Demar, M. J. S., 123.De Witt, T. W., 28.Dexter, T. H., 91.D'Eye, R. W. M., 98.Dhar, M. L., 115.Dialer, K., 169.Diamond, H., 34.Diatkina, M., 15.Dice,'J. R., 155.Dickson, D. H. W., 12.Dickson, G. T., 192.Diehl, H., 32, 271, 303.Diemer, G., 141.Dienes, G.J., 27.Diepen, G. A. M., 9.Dierkesmann, H., 303.Dietrich, L. S., 237, 242.Dilke, M. H., 36.Dinerstein, R. A., 156, 284.Dingle, R. B., 8.Dittmer, K., 152, 185, 191,Divis, L., 271.Dixon, J. K., 301.Dixon, R. M., 138.Dobkina, E., 19, 21.Dodd, G., 111.Dodds, E. C., 223.Dodgen, H. W., 109, 110.Doering, W. E., 122, 148,Dolby, D. E., 165.Dole, M., 28.Domange, L., 98.DominB-BergtSs, (Mme.) M.,Donohue, J., 80, 83, 103.Dopel, R., 288.Dornberger, K., 33.Dornbush, A. C., 238.Dorp, D. A. van, 141, 169,170, 171, 172, 249.Dostrovsky, I., 116, 117,118.Doughty, M. A., 119.Douglas, A. M. B., 66.Douglas, D. L., 107.Down, L., 293.256.255.192.155.108INDBX OF AUTHORS' NABMIOS.309Downer, E. A. W., 119.Drake, N. L., 148, 159.Dranen, J. van, 8.Dreiding, A. S., 142.Dresdel, E., 136.Drill, V. A., 240, 256.Drummond, J. C., 255.Dryden, L. P., 236.Dublin, W. B,, 303.Dubnikov, L. M., 108.Duckworth, H. F., 90.Diirst, O., 142.Du Feu, E. C., 152.Dulou, R., 183.Duncan, A. B. F., 14.Duncan, J. F., 28.Dunlap, G. W., 87.Dunn, R. W., 289.Dunworth, 3. V., 87.Dupont, J., 130.Dupuis, T., 269.Durell, J., 261.Dutt, N. K., 96.Dutta, A. K., 41.Duval, C., 269, 270.Duval, T., 269.Du Vigneaud, V., 192.Duyckaerts, G., 279.Dykstra, H. B., 158.Eakin, R. E., 238, 242, 243.Eastman, R. H., 154.Eaton, M., 9, 17.Eby, L. T., 147.Eck, J. C., 191.Eckart, C., 8.Eckoldt, H.E., 157, 158.Eddy, R. W., 115.Eder, H., 209.Edgecombe, L. J., 292.Edgell, W. F., 13.Edgerton, R. O., 176.Edisbury, J. R., 183, 255.Edeall, J. T., 224.Edse, R., 299.Edwards, H., 14.Edwards, H. D., 13.Edwards, 0. E., 143, 205.Edwards, R. R., 87, M7.Eekelen, 33. van, 183.Egerton, Sir A., 32.Eggersgluess, W., 94.Egloff, G., 17.Eguchi, M., 290.Ehrensvard, G. C. H., 195.Ehresvard, G., 187.Ehrlich, J., 143.Ehrlich, P., 25.Eigen, E., 238.Eisbman, 303.Eisenbrand, J., 133.Eley, D. D., 17, 34, 36.Eliel, E. E., 145.Eliel, E. L., 194.Elks, J., 192.Elliott, A,, 227.Elliott, D. F., 188, 191.Ellis, B., 235.Ellis, C. D., 286.Ellis, M., 89.El Ridi, M. S., 246.El Shamy, H. K., 109.Elvehjem, C. A., 230, 231,236, 237 242, 243.Elyash, E.S., 13.Embree, N. D., 168, 176,180, 181, 183, 184, 252.Emelbus, H. J., 12, 87, 102,109, 110.Emmerie, A., 183.Emmett, P. H., 28.Emmick, R. D., 191.Engel, C., 233, 242.Enghoff, H., 292.England, B. D., 128.English, J., jun., 163.Enns, T., 191.Epstein, M., 236.Epstein, S., 90.Erbacher, O., 10, 87.Ercoli, N., 172.Ericsson-Quensel, I. B., 223.Erlenmeyer, H., 194.Erlich, P., 71.Ernst, T., 23.Errera, J., 276.Ershoff, B. H., 236, 237.Esh, G. C., 258.Etienne, A., 282.Eugster, C. H., 141, 143,Euler, H. von, 177,183,257.Evans, A., 119.Evans, A. A., 119.Evans, A. G., 18, 116, 117.Evans, C. C., 11, 30.Evans, G. E., 12.Evans, H. J., 294.Evans, H. T., 22, 73, 80.Evans, M. G., 15, 106, 116.Evans, 'U.R., 111.Evana, W., 195.Evans, W. E., 187, 192.Ewens, R. V. G., 101.Ewing, F. J., 53, 54, 68.Fabelinsky, I., 18.Fainer, P., 271.Fairbank, H. A., 8, 89.Fairbrother, F., 13, 30, 105.Faivre, R., 24.Fakin, T., 245.Fand, T. I., 148.Fanelli, R., 107.Fankuchen, I., 224.Fantes, K. H., 235.Faraday Society, 26, 29, 58.Farber, M., 155.Farber, S., 231.Farkas, A,, 34.Farlow, M. W., 189.Farqubmon, J., 42.150.Farthing, A. C., 225, 227.Fasold, F., 256.Fathallah, A. H., 96.Faucherre, J., 99, 275.Fawcett, J. S., 125,Feher, F., 17, 107.Feigl, F., 271.Feitelson, B. N., 174.Feitknecht, W., 91.Feldmenn, C., 96.Fellenberg, T., 256.Fdndant, (Mme.) S., 104.Fennimore, C. P., 90.Fenske, M. P., 276, 278,Ferguson, L.N., 14.Fernando Milanes, G., 232,Feuer, I., 269.Feurer, M., 145.Fidler, J., 271.Field, E., 297.Fields, M., 14.Fierz, H. E., 284.Fieser, L. F., 141, 160.Fieser, M., 141.Fillman, J. L., 193.Finar, I. I., 186.Fine, P. C., 7.Fink, R. M., 191.Finkelstein, R. J., 22.Finland, M., 240.Fischer, E., 212, 219.Fischer, F. O., 281.Fischer, H. 0. L., 167, 168.Fishburn, B., 153, 188.Fisher, D. G., 33.Fisher, E., 92.Fisher, R. B., 272.Fitt, T. C., 300.Flagg, J. F., 102, 271, 297.Fleming, C. H., 117.Fletcher, R. S., 116.Fleuret, M. A. M., 283.Fling, M., 195.Flood, H., 29.Fodor, P. J., 186.Foe,, M., 26.F~trland, T., 29.Fijirster, T., 32.Fogo, J. K., 304.Folkers, K., 140, 211, 234,Ford, J. H., 187.Fordham, W. G., 159.Forestier, H., 27.Forrest, H.S., 201.Foss, O., 107, 108.Fossen, P. van, 295.Foster, A. G., 28.Foster, G. L., 216.Foster, J. C., 238.Fouinat, (Mlle.) F., 106.Fowden, L., 128.Fox, S . W., 195.Frwnkel, G., 231.280.240.235310 INDEX OF AUTHORS’ NAMES.Fraenkel-Conrat, H., 186.Franpois, F., 277, 278.Frank, V. S., 195.Frankel, J. S., 165.Frankel, M., 225, 226.Franklin, A. L., 234, 236,Fraps, G. S., 246.Freed, S., 97.Freiser, H., 271.French, C. M., 38.Frey, G., 282.Fried, S., 100.Friedel, R. A., 90.Frieden, E., 193.Friedkin, M., 239.Friedlander, H. N., 288.Friedlander, J. K., 295.Friedman, H., 49.Friedmann, L., 144.Fritsch, F., 243.Frodl, V., 301.Fruton, J. S., 122, 186,Fu, F.Y., 211.Fuchs, K., 44.Fukui, J., 246.Fuller, A. T., 191.FUOSS, R. M., 29.Fusek, J. F., 140.Fuson, R. C., 125.Gedamer, 20 1.Gadeau, R., 29.Gaffney, G. W., 141.Gaillot, E., 102.Galat, A., 185, 187, 191.Galinovsky, F., 197, 199.Gallais, F., 105.Galt, J. K., 20.Gamble, E. L., 95.Gamow, G., 87.Ganguly, J., 256.Garcia Lopez, G., 232, 240.Garrett, A. B., 32, 112.Garrison, W. M., 296.Garst, R., 192.Gasser, A., 275.Gates, M., 200.Gatterer, A., 301.Gaudry, R., 187, 191, 193.Gauguin, R., 101.Gaydon, A. G., 32.Gayer, K. H., 112.Gazzola, A. L., 230.Gee, A., 12.Gee, G., 31, 32, 33.Geiger, A., 181.Geller, B. A., 292.Gellner, 0. H., 18.Gent, W. L., 92.George, P., 106.Gerding, H., 17, 278.Gergely, J., 15.Gernandt, B., 260.Gest, H., 87.238.189.Ghosa, Sir J.C., 16.Giauque, W. F., 9, 89, 93,Gibney, R, B., 41.Gibson, C. S., 92.Gibson, G. P., 252.Gigli, A., 31.Gilbert, J. B., 186.Gilding, H. P., 255.Gilham, E. W. F., 297.Gillam, A. E., 180, 183, 245,Gillespie, J. S., 141.Gillespie, R. J., 131.Gilliam, 0. R., 13.Gillis, J., 60.Gillis, M. B., 240.Gillot, R. J., 64.Gilman, H., 158, 171,Gilpatrick, L. O., 304.Ginger, L. G., 157, 162.Giulotto, L., 31.Gladding, J. K., 174.Gleditsch, (Mlle.) E., 102.Glemser, O., 25, 100, 101,Glick, D., 169.Glockler, G., 12, 103, 277.Glover, J., 252, 255, 256,257, 262.Go, Y., 225.Godshalk, J. B., 299.Goddard, D. R., 103, 131.Goehring, M., 107.Gogan, A. H., 230.Gogate, D.V., 8.Golberg, L., 231.Goldberg, E., 289.Goldberg, M. W., 154.Goldblatt, M., 10.Golden, S., 13.Goldschmidt, B., 285, 288.Goldschmidt, V. M., 45, 64,Goldsmith, D., 189.Soldwater, W. H., 214.Solibersuch, E. W., 106,Zoltz, R. K., 292.Zolumbic, C., 122.Jonzaldz, E. L., 271.Jooderham, W. J., 293.Joodeve, C. F., 261, 263,Joodwin, T. H., 96.Joodwin, T. W., 171, 182,248, 255, 256, 257, 262.foodwin, W. G. M., 138.2opa1, R., 26.Jordon, A. H., 185,220.Jordon, J., 9.Jordon, L., 270.Jordon, L. B., 130.Xordy, W., 13, 14.3ore, R. C., 302.Joria, C., 91.lorman, J. G., 13.101.249.109.66.265.Gorter, C. J., 40, 41.Goss, G. C. L., 182.Goubeau, J., 12, 13, 93, 95,Gould, R. G., 171.Gourevitch, M., 184.Goutard, R., 203.Goutarel, R., 203, 204.Gouverneur, P., 281.Grafe, K., 189.Graham, D.C., 29.Graham, J., 131.Graham, W., 170.Grahame, D. C., 294.Granit, R., 183, 259, 260,Gray, E. Le B., 180, 281.Gray, F. W., 38.Gray, J., 101.Graydon, W., 270.Grayson, J. M., 248.Grebe, W., 302.Greear, J. A., 270.Green, E. L., 165.Green, H. S., 8.Greenaway, H. T., 19.Greenberg, S, M., 245, 246.Greene, J. B., 44.Greene, R. D., 216, 238.Greenlee, K. W., 141, 147.Greenstein, J. P., 186.Greenwood, N. N., 25.Gregg, J. R., 283.Gregg, S. J., 28, 29, 93.Gregory, N. W., 105.Gregory, R. A., 256.Greiner, J. W., 187.Gresham, T. L., 149.Greuter, F., 256.Grewe, R., 200.Gridgeman, N. T., 169, 252.Grieger, P. F., 29.Griffith, A.M., 191.Griffith, R. O., 111.Griffiths, J. H. E., 41.Grillot, E., 39, 40, 102.Grilly, E. R., 89, 299.Gronwald, A,, 212.Grcanwald, F., 74.Groschke, A. C., 235, 236.Grosse, A. V., 10, 278.Grossfeld, I., 225.Grossi, F. X., 173, 174, 176,Grube, G., 50.Grubenmann, W., 194.Gruber, W., 198.Griissner, A., 200.Griittner, B., 30, 101.GruLberg, L,, 21.3runlund, J. M., 10.Srunwald, E., 122.SucSrillot, A., 184.h e x , W., 169.Juggenheim, K., 252.Zuiter, H., 81, 99, 102, 111.102,.278, 279.266.179INDEX OF AUTHORS’ NAMES. 31 1Gullberg, J. E., 269.Gupta, A. K., 12.Gurin, S., 187, 191.Gurney, C., 26, 27.Guseva, L. N., 66.Gutfreund, H., 224.Gutowsky, H. S., 100.Gwathmey, A. T., 27.Gwinn, W. D., 18, 31.Gysae, B., 89.Gysling, H., 274.Haagen-Smit, A.J., 191Haak, F. A., 146.Haasser, C., 27.Haayman, P. W., 73.Hackspill, L., 93, 103.Haden, W. L., 296.Haendler, H. M., 91.Hliusser, V., 101.Hagemeyer, H. J., 148.Hagerty, R. P., 11.Haggett, E , 151.Hahn, G., 197.Hahn, H., 37, 71.Hahn, R. B., 270.Haines, G., 288.Haissinskv. H.. 88.Haissinskg; M.; 11, 87, 98,Halban, H. von, 104, 133.Halberstadt, E. S., 131.Haldane, K. N., 138.Halford, J. C., 9.Hall, C. A., 240.Hall, D. A., 233.Hall, L., 20.Hall, R. T., 284.Haller, A., 163.Haller, H. L., 166.Halliday, D., 40, 41.Halpin, J. C., 236, 237.Hamano, S., 169.Hamburger, G., 59, 76, 77.Hamill, W. H., 287.Hamlin, K. E., 142.Hammell, E. F., 89.Hammett, L. P., 115, 126.Hammond, J.C., 235.Hampson, G. C., 16.Hanby, W. E., 122, 226.Handrick, G. R., 135.Hanford, W. E., 148.Hanna, J. G., 293.Hansen, C. A., 299.Hansley, V. L., 158.Hanslow, G. A., 14.Hanson, C., 122.Hanson, H. T., 186.Hantzsch, A., 132, 133.Hanze, A. R., 169, 249.Harder, H., 19.Harding, W. M., 242.Hardwick, T. J., 97.Hardy, W. B., 212.Hare, D. G. C., 301.108.Harfenist, M., 141, 142.Hargrave, K. R., 106.Harington, Sir C., 191, 193,Harker, D., 12, 58, 60, 79.Harkins, W. D., 28, 29.Harper, A. E., 242.Harper, S. H., 166.Harrap, B. S., 29.Harrington, T. M., 142, 171.Harris, E. J., 32.Harris, I., 102.Harris, P. L., 252, 256.Harrison, G. R., 301.Hart, E. B., 230.Harteck, P., 299.Harting, W. F., 195.Hartung, W.H., 187, 192.Hartley, G. S., 122.Hartman, A. M., 236.Hartmann, H., 97.Hartmann, M., 247.Hartridge, H., 260.Harvey, B. G., 100.Harvey, J. L., 91.Haskin, J. F., 277.Hassel, O., 16, 58.Hassler, G. L., 300.Haszeldine, R. N., 110.Hatch, L. F., 130, 145.Hatem, S., 39.Haugaard, G., 222, 223.Hauge, S. M., 237.Haurowitz, %., 218, 226.Hauser, C. R., 153, 154,Hausmann, K., 242.Hawkings, R. C., 10.Hawkins, E. G. E., 181,Haworth, R. D., 143, 201.Hayden, R. H., 93.Hayek, E., 88, 98.Heal, H. G., 102.Heathcote, J. G., 185.Heatley, N. G., 296.Hecht, S., 261.Heekrotte, W., 10.Kegedus, B., 195.Heide, E. C. von der, 232.Heidelberger, C., 194.Heidemann, E. R., 256.Heidt, L. J., 97.Heilbron, Sir I., 128, 140,169, 170, 171, 172, 173,175, 176, 177, 178, 179,180, 181, 182, 183, 194,247.229.163.182, 184.Heilmann, E.L., 73.Keinle, R. W., 232, 236,Heinrich, R. A,, 233.Keinzelman, D. C., 165.Heiss, J., 20.Heldman, M. J., 160.Heller, W., 224.237.Hellner, E., 67.Helman, N. E., 284.Helmholz, L., 74, 81.Helmkamp, R. W., 191.Hems, B. A., 192.Henbest, H. B., 174, 178.Henderson, R. B., 122.Henderson, R. S., 13.Henderson, W. J., 290.Hendlin, D., 237, 238.Hendus, H., 20.Henne, A. L., 145, 147.Henriet, L., 15.Henry, T. A., 195.Herbo, C., 269.Hermann, C., 66.HBrold, A., 90.Heron, A. E., 281, 282.Herringshaw, J. F., 31.Herriott, R. M., 224.Hershberger, W. D., 13.Hertwig, K., 16, 95.Hertz, W., 191.Herz, W., 152, 185, 192.Herzfeld, K.F., 14.Hess, D. C., 96.Hess, H. V., 122.Heuser, G. F., 230.Heusser, H., 145.Hevesy, G. von, 285, 288.Hey, D. H., 115.Heyd, F., 23, 101.Heymann, E., 29.Hickey, J. W., 11.Hickman, K., 180.Hickman, K. C. D., 252.Hieber, W., 112.Hilal, 0. M. M., 96.Hildebrand, J. H., 12, 13,Hill, G. R., 112.Hill, W. K., 39.Hiller, A,, 282.Hillger, R., 13.Hillier, J., 304.HillmaM, A., 189.Hillman, G., 186, 189.Hills, H. W. J., 119.Hindley, N. C., 169.Hindman, J. C., 98, 100.Hinshelwood, Sir C., 110,116, 136.Hippel, A., 22.Hipple, J. A., 298.Hitchcock, F. A., 298.Hobbs, E., 105.Hocart, R., 90.Kochstein, F. A., 140, 142.Hockstra, H. R., 102.Hodge, H. C., 181.Hodgkin, D., 235.Kodson, A. Z., 234.Honigschmid, O., 90, 93,Hoffman, D.O., 284.Koffmann, C. E., 238.110, 139.103312 INDEX OF AUTHORS’ NANES.Hoffmann. F. W.. 155.Hoffmann:La Roche & Co.,173, 174.Hofman, J., 153.Hofmann, A., 142.Hofmeister, F., 212.Hogan, A. G., 237.Hogarth, C. A., 25.Hoge, If. J., 99.Hogg, B. J., 90.Hohmann, E., 19.Holden, R. B., 93.Holley, R. W., 149.Holliday, E. R., 235.Hollies, N., 28.Hollis, G. L., 8.Holm, 304.Holm, O., 10.Holman, E. J., 113.Holmes, H. L., 154.Holmes, H. N., 168.Holmes, 0. G., 112.Holowatyj, M., 108.Holt, E. K., 277.Holth, T., 270.Holzbecher, Z., 271.Honig, R. E., 18.Hook, W. H., 163.Hoover, S. R., 33, 218.Horeau, A., 283.Homing, E. C., 140, 281.Homing, M. G., 281.Horron, B. W., 285.Horwin, L., 153.Horwitz, W., 112, 277.Hoshowsky, S.A., 112.Hovorka, V., 271.Howe, E. E., 188, 191, 193.Hsiang, J. S., 41.Hsi-Teh-Hsieh, 14.Huang-Minlon, H. T., 148,Hubbard, R., 262.Huber, W., 140, 169, 173,Hudson, B. E., 153.Hudson, B. E., jun., 163.Huebner, C. F., 155.Huckel, W., 19.Huttig, G. F., 35.Huff, G., 109.Huff, J. W., 237, 238,Huffin, H. M., 9.Huffman, H. M., 17.Hughes, E. D., 103, 115,116, 117, 118, 122, 128,130, 131, 136.Hughes, E. W., 60, 62.Hughes, G. X., 196, 210.Hughes, R. H., 13.Huisgen, R., 209.Hull, R., 225.Hunde, D. N., 105, 112.Hurne, E. M., 263.Hume-Rothery, W., 42, 48,159.249.54, 66.Humphrey, C. W., 106.Hunsdiecker, C., 155.Hunsdiecker, H., 149, 155.Hunt, E. B., 31.Hunter, J.A., 298.Hunter, P. C., 95.Hunter, R. F., 10, 181, 182,Hunziker, F., 154.Hurd, D. T., 94.Hurenkamp, J. B. G., 157.Hutchings, B. L., 230,Hutchinson, U. E., 10.Hutchinson, H. P., 8.Hutchinson, T., 11.Hutchison, C. A., 93.Hutchison, T. S., 41.Hutner, S. H., 238.Hutter, J. C., 104.Ignatowicz, S., 29.Iley, R., 23.Illuminati, G., 113.Inatome, M., 295.Ingersoll, A. W., 160.Inghram, M. G., 10, 90,96.Ingold, C. K., 19, 103, 115,116, 118, 119, 121, 122,126, 127, 128, 130, 131.Ingold, E. W., 121.Ingraham, L. L., 122.Ingram, B. L., 273.Ingram, G., 281.Inhoffen, H. H., 141, 142,Innes, E. M., 231.Innes, J., 231, 242.Ipatiev, V. N., 33.Ireland, J., 255.Irimescq I., 282.Irrmann, F., 24.Irving, H., 271,274.Irving, J.W,, 112.Irving, L., 296.Irving, R., 111.Isler, O., 140, 169, 173, 175,Israels, M. 0. G., 232, 241.Itallie, L. van, 210.Ito, T., 79.Itterbeck, A. van, 8.Ivanovics, G., 226.Ivie, J. O., 300.Jackman, M., 153.Jackman, M. E., 194.Jackson, F. L., 166.Jacobi, E., 111, 196.Jacobi, W. R., 298.Jacobs, I., 15.Jacobs, J., 28.Jacobs, M. B., 301.Jacobs, T. L., 170.Jacobs, W. A., 155.184.238.171, 174.249.Jacobsen, C. F., 221, 225.Jacobson, B., 91.Jacobson, H. F., 278.Jacobson, M. J., 166.Jaeger, W., 300.Jaffray, J., 26.Jager, A., 302.James, D. M., 131.James, M. F., 237.James, R. W., 25, 58.Jander, G., 30, 101, 104.Janot, M. M., 202, 203,Jansen, J. E., 149.Jeffrey, G. A., 63, 64, 83,Jeger, O., 142, 147, 178.Jen, C. K., 13.Jenkins, F A., 10.Jerslev, B,, 83.Johannsen, T., 90, 93.Johannsen - Grohling, L.,Johnson, A.W., 169, 173,Johnson, B. C., 233, 237.Johnson, G., 258.Johnson, G. L., 99, 111.Johnson, H. S., 28.Johnson, J. E., 140, 145.Johnson, J. L., 198.Johnson.. J. R., 10, 114.Johnson, R. M., 246, 256.Johnson, W. M., 17.Johnston, C., 245.Johnston, C. H., 246.Johnston, H. L., 8, 89, 93.Johnston, W. T. C., 138.Jolibois, P., 104.Joly, M., 29.Jonassen, H. B., 91.Jones, B., 138, 139.Jones, E. C. S., 151.Jones, E. R. H., 125, 128,130, 140, 168, 169, 170,171, 173, 174, 175, 176,177, 178, 179, 247.Jones, F. T., 245.Jones, H., 43, 44, 52.Jones, hf. J., 233Jones, R. G., 144, 158, 159.Jones, R.N., 14, 103.Jones, R. W., 103.Jones, T. S. G., 184.Jones, V. V., 198.Jones, W. E., 180, 181, 182,Jones, W. M., 9, 101.Jonnard, R., 282.Jorgensen, E., 199.Joris, Q. G., 10.Josien, M.-L,, 92.Jost, J., 203.Jouanneteau, J., 182, 184,204.103.103.182.257, 258.189.263INDEX OF AUTHORS' NAMES. 313Jouin, Y., 269.Joyner, L. G., 28.Joyner, R. A,, 106.Jucker, E., 171, 183, 244.Jukes, T. H., 229, 232, 233,Julia, M., 170.Julian, P. L., 141, 143, 145,204, 205.Julius, H. W., 183.Jura, G., 19, 28.Juza, R., 37.Kaczka, E., 235.Kahn, S., 179.Kainz, G., 199.Kalckar, H. M., 233.Kaley, M. W., 252.Kamecki, J., 96.Kampitsch, E., 273.Kapur, P. L., 36, 42.Karanth, K. P., 142, 143,Karatras, A., 28.Karbe, K., 89.Karpel, W.J., 204.Karplus, R., 14.Karrer, P., 141, 142, 143,145, 150, 170, 171, 172,175, 176, 177, 178, 181,183, 184, 203, 244.Kartus, S., 240.Kascher, H. M., 252.Kasper, J. S., 12, 58, 60.Kass, J., 160.Kassell, B., 214.Katchalski, E., 225, 226.Kato, E., 228.Katz, J. J., 102.Katz, L., 194.Katz, M., 299.Katzman, J., 299.Kaufmann, S., 141.Kaur, G., 42.Kay, H. F., 22.Kayas, G., 11.Kazanski, B. A', 146.Kazenko, A., 234.Keenan, C. W., 103.Keighley, G., 191.Keil, B., 199.Keil, W., 162.Keilholtz, G. W., 304.Keller, A., 91.Keller, E. B., 190.Kelley, B., 256.Kellner, L., 17.Kellogg, K. B., 110.Kelly, K. J., 19.Kelso, J. R., 90.Kemerer, A. R., 246.Kendall, J. T., 41.Kennard, O., 78.Kennedy, J.W., 289.Kenner, G. W., 141, 145.Kenner, J., 161.234, 235, 236, 238.177.Kenty, C., 297.Kenyon, J., 119, 121, 129,Kepner, R. E., 129, 131,Kern, D. M. H., 99.Kerrigan, V., 110.Kersten, J. A. H., 246.Keskin, H., 159.Kessler, M., 14.Keston, A. S., 216.Ketelaar J. A., 18, 23, 74,79.Ketelle, B. H., 289.Key, C. W,, 298.Keyser, L. S., 160.Khanna, M. L., 40.Kharasch, M. S., 129, 132.Khol, F., 101.Kidd, A. A., 189.Kiehl, J. G., 93.Kieselbach, R., 297.Kiessling, R., 68, 94.Kimball, C. P., 191.Kimball, G. E., 123.Kimball, R. H., 283, 294.Kinell, P.-O., 279.King, D. T. P.. 290.King, F. E., 189.King, G., 33.King, H. J. S., 113.King, J. A., 187, 188.King, L. C., 110.Kingery, W. D., 105.Kirbrick, A.C., 218.Kirby, H., 185.Kirby, K. S., 203.Kirk, P. L., 269.Kirshenbaum, A. D., 10.Kiselev, V. V., 201.Kissinger, L. W.. 135.Kitaigorodski, A. J., 17.Kitay, E., 238, 239.Kitchener, J. A., 29.Kittel, C., 40, 41.Klasens, H. A., 157.Klee, 201.Klein, G. E., 76.Klein, H. A., 19.Kleinberg, J., 13, 90, 154.Klemm, L., 19.Klemm, W., 19, 24.Klenk, M., 153.Klevens, H. B., 14, 224.Klimova, V. A., 281.Kljnger, P., 304.Klmgler, W., 71.Klinkenberg, 9.Klipp, R. W., 284.Klosterman, H. J., 190.Klotz, I. M., 33.Knabe, R., 50.Knight, C. A., 214.Knott, E. B., 151.Kobe, K. A., 293, 295.Kochanovska, A., 23, 101.Koch, W., 252.155.Kocher, K. von, 237.Kocher, V., 186, 238.Koc6r, M., 207, 210.Koditschek, L. K., 237, 238,Koepfli, J.B., 210.Korosy, F., 91.Koster, W., 26.Kofler, M., 140, 169, 173,Kohl, F., 23.Kokes, E. L., 218.Kolb, W , 17.Kolkmeijer, N. H., 58.Kolp, D., 97.Kolthoff, I. M., 106, 112,Komarewsky, V. I., 105.Komzak, A., 196.Kon, S. K., 245, 248, 256.Kondo, H., 200, 202.Koniuszy, F. R., 234, 235.Konovalova, R. A., 201.Kooyman, P. L., 32.Korn, A. H., 33.Korscak, V. V., 158.Korsching, H., 89.Korshm, M. O., 281, 284.Kostemans, D., 198.Koteswaram, P., 276.Kramer, B., 258.Kramers, W. J., 110.Kraus, A. C., 29.Kraus, C. A., 30.Kraus, E. B., 28.Kraus, K. A., 98, 99.Kraus, R. F., 256.Krebs, H. A., 253.Krehl, W. A., 231, 258.Krider, J. L., 237.Krieger, F. J., 9.Krishnan, R. S., 23.Kritchevsky, E. S., 98.Kritchevsky, J., 129.Kruissink, C.A., 21.Krumholz, P., 112.Krutter, H. M., 47.Krynitsky, J. A., 140.Kubachewski, O., 89.Kubo, R., 33.Kuehl, F. A,, 211.Kuhn, H., 14, 33.Kuhn, L. P., 132.Kuhn, R., 34,169, 170, 171,Kuhn, W., 14, 21.Kummerow, F. A., 166.Kunitz, M., 224.Kupriyanova, L., 300.Kuras, M., 272.Kurbatov, J. D., 11.Kuzminyka, I. N., 301.Kwasnik, W., i l l .Labraume, L., 130.Lacey, R. N., 130, 175.241.249.272.247314 INDEX OF AUTHORS' NAMES.La Chapelle, T. J., 100.Lacher, J. R., 38.Lacroute, P., 87.La Forge, F. B., 153.Lagemann, R. T., 20.Lagercranz, A., 82.Lahey, F. N., 210.Laitenin, H. A., 31, 91, 274.Lally, J. A., 238.Lambooy, J. P., 192.Lambourne, L. J., 138.Lampen, J. O., 233.Lamure, J., 94.Lane, C.T., 89.Lane, J. F., 129.Lange, H., 102.Langheirn, R., 37.Langston, W. C., 230, 231.Lantz, 137.Laptev, N. G., 135.Lardelli, G., 147.Laskowski, M., 234.Lassettre, E. N., 18.Laszlo, D., 232.Laub, H., 299.Laubengayer, A. W., 13.Lauer, J. L., 279.Laves, F., 67.Lavoipierre, M., 231.Lazur'evskii, G. V., 199.Lederer, E., 180, 249, 261.Lee, S. W., 173, 176.Leech, H. R., 109.Leendertse, J. J., 294.Le FBvrs, R. J. W., 19, 38.Lehman, R. H., 285.Leidheiser, H., 27.Leighton, 9. A., 294.Leininger, E., 105.Leininger, R. F., 111.Leitz, F. J., 97.Leko, A. M., 94.Leland, W. T., 94.Lemieux, R. U., 185.Lennartz, T. A., 156.Leonard, N. J., 148, 199.LePage, G. A., 183.Le ROUX, L. J., 119.Lescher, V.L., 281.Lesein, E., 15.Letina, V. S., 283.Leuchs, E., 207, 209.Leuchs, H., 225.Leuchtenberger, C., 232.Leuchtenberger, R., 232.'Levernnz, L., 17.Levering, D. R., 140.Levi, D. L., 19.Levi, H., 288.Levin, H., 293.Levin, R. H.. 141.Levine, A. A., 191.Levine, R., 153.Levy, A. L., 194.Lewis, A. D., 142, 169, 172.Lewis, C, D., 187.Lewis, D. G., 179.Lewis, J. F., 158.Lewis, U. J., 243.Lewis, W. B., 87, 112,Lewisohn, R., 232.Libby, W. F., 10, 109, 287.Libman, D. D., 186.Lichblan, J., 258.Lichtenstein, R. M., 22, 87.Liddell, H. F., 283.Lieber, E., 140.Liebhafsky, H. A., 102, 301.Lien, A. P., 146.Lieneweg, F., 299.Lifschitz, I., 40.Lile, W. J., 113.Lilienfield, W. M., 154.Lillie, R. J., 236.Lindbad, K., 158.Linden, S.C., 130.Linden, S. L., 170.Linderstram-Lang, K., 221,Adlar, H., 173.indner, R., 290.Adqvist, I., 75.ingane, J. J., 108, 109.h n e l l , W. H., 177.3pkin, D., 304.Apscomb, W., 73, 83.Ater, M. W., 83.,iston, M. D., 302.dtmanowitsch, M., 104.,ittle, P. A., 231.,ittman, B., 284.Avingston, R., 32.Avingwood, J. J., 290.Jewellyn, F. J., 83.Jobene, R., 297.Joewe, S., 141, 142.dondon, F., 89.,ong, C. A., 194.,ong, D. A., 279.,ong, L. H., 100.Longenecker, H. E., 166.Longuet-Higgins, H. C., 15,Lonsdale, K., 22, 23, 58.Loon, J. van, 166.Loon, M. V., 139.Lopez Toea, R., 240.Loriente, E., 271.Loriers, J., 26.Lounsbury, M., 10,90.Love, M., 249.Lovelace, M. E., 273.Lovern, J. A., 255.Lowy, P.H., 191.Lu, c. s., 119.Lucas, H. J., 122.Lucht, C. M., 12, 58.Luckey, T. D., 230.Luttringhaus, A., 155.Luft, K. F., 302.Lumbroso, H., 16.229.dink, J., 130.95.Lund, E. W., 58.Lundell, G. E. F., 89.Lundqviat, D., 69.Lunshof, H. J., 157.Lutonski, L. F., 148.Luttinger, J. If., 40, 41.Luttrop, E. S., 296.Lutz, G., 25, 109.Lutz, R. E., 141.Luzatti, M. V., 80, 81.Lykken, L., 280.Lyne, M., 103.Lvon. L. L.. 160.L$thgoe, R. J., 261, 263,265.Lyttle, D. A., 152, 186.McAleer, W. J., 153.McCallum, K. J., 112.McCarthy, W. C., 192.McCartney, J. S., 277.McCarty, C. N., 97.McCarty, L. V., 94.McCay, C. M., 248.Maccoll, A., 16.McCombie, J. T., 128.McConnell, H., 96.McCormack, R. B., 238.McCormick, R.H., 278.McCulloch, F. W., 284.McCullough, J. D., 71, 293.MacDiarmid, A. G., 107.MacDonald, D. K. C., 31.McDonald, I. R., 138.MacDonald, N. S., 173, 180.McDonald, R. A., 68, 293.McDowell, G. A., 32.McElvain, S. M., 154.MeFarlane, W. D. M., 182.Macgillavry, C. H., 23, 58,Macheboeuf, M., 185.Machemer, P. E., 282.Machevin, W. M., 105.McIntosh, A. O., 93.McIntosh, A. V., 141.McIntosh, R., 28.McKee, R. L., 143.McKenna, F. E., 283.McKennis, H., 141.McKibbin, J. M., 230.Maekle, H., 18.McKusick, B. C., 147.McLamore, W. M., 205.McLaren, A. D., 33.McLeod, L., 28.McMeekin, T. L., 213, 214,McMillan, E. M., 10.McNab, W. M., 282.McNally, J. R., 301.Macnamara, J., 106.McNutt, W. S., 238, 239.McOmie, J. F.W., 170.R.lacQueen, A. D., 252.McQuillin, F. J., 152.71, 74, 79, 80.221, 224INDEX OF AUTHORS’ NAMES. 315McSkimin, H. J., 20.McVey, W. H., 100, 102.MacWalter, R. J., 255.Madden, S. C., 191.Maddock, A. G., 87, 98,Maffei, F. J., 269.Magat, M., 21.Maget, K., 91.Maggs, F. A. P., 29.Maginnity, P. M., 285.Magmusson, L. B., 100.Magnani, A., 143, 204, 205.Magreli, A., 72, 73.Majumdar, S. K., 41.Makarov, J. A., 157.Malatesta, L., 102.Malick, V., 275.Malm, J. G., 93.Mandour, A. M. M., 115.Mann, W. B., 10.Mannelli, G., 273.Manning, M. F., 44, 47.Manning, P. D. V., 230,231,Manske, R. H. F., 200.Manten, A., 247.Marcali, K., 283.Margolis, E. T., 129.Marion, L., 143, 198, 200,Marschner, R. F., 156.Marsden, A., 36, 37.Martin, A.J. P., 185, 220,Martin, C. C., 279.Martin, C. J., 142.Martin, D. R., 13.Martin, D. S., 110.Martin, G. J., 194, 233.Martin, G. L., 105.Martin, H., 99, 130.Martin, K. F., 90.Martin, M., 15.Martin, (Mlle.) M., 87.Martin, R. H., 151.Martin, R. P., 192.Marvel, C . S., 190.Marvin, M. D., 303.Masi, J. F., 99.Mason, G. E., 295.Mason, L. S., 95.Mason, R. G., 159.Mason, W. P., 20, 22.Masson, R., 40.Mastermann, S., 122.Mathews, M. B., 143.Mathieson, A. McL., 23.Mathieu, J. P., 12.Mathur, K. N., 36.Matsen, F. A., 14.Matsui, M., 175.Mattauch, J., 11, 87.Matthews, F. W., 93.Matthias, B., 22.Mattocks, A. M., 187, 192.Mattoon, R. W., 29.107.205.252, 258.Mattson, F. H., 255, 256.Matyas, Z., 44.Maw, G.A,, 115.Maxted, E. B., 36.Maxwell, G. E., 111.May, C. G., 16.Mayer, J., 108, 258.Mayer, M. G., 87.Maylott, A. O., 159.Mayo, F. R., 129.Mazee, W. M., 157.Mead, F. B., 210.Mead, T. H., 169, 255.Meakins, R. J., 21.Medalia, A. I., 106.Medem, F. G., 247.Meek, H. V., 110.Meek, J. S., 153.Megaw, H. D., 22, 78.Meggers, W. F., 300.Meggy, A. B., 33.Mehl, J, W., 255, 256.Mehl, R. F., 11.Mehlum, J., 157.Mehrota, R. C., 273.Meisenheimer, J., 130.Meitner, L., 288.Melamed, S., 148, 159.Melander, L., 134.Melchior, J. B., 189.Mellanby, E., 258.Mellon, E. F., 33.Mellor, D. P., 100.Melville, D. B., 190.Mengelberg, M., 207.Menzies, A. C., 277.Menzies, R. C., 113.Merritt, F. R., 13.Merritt, L. L., 271.Meserve, E.B., 246.Meth, E., 174.Mettler, E., 268.Meunier, P., 182, 183, 184,Meyer, E. W., 145, 204.Meyer, H., 174, 175.Meyer, L., 8, 89.Meyer, L. M., 231, 242.Meyers, M. C., 232, 240.Meystre, C., 141, 142.Michel, G., 279.Middlesworth, L. van, 189.Midzushirna, S., 278.Miescher, K., 141, 142.Mikhail, H., 38.Milas, N. A., 142, 169, 171,172, 173, 174, 176, 179,180.Miles, G. L., 98.Miles, S. H., 284.Mileur, R., 282.Millen, D. J., 131.Miller, B., 299.Miller, C. E., 107.Miller, C. H., 14, 279.Miller, R. D., 10, 302.253, 266.Miller, R. R., 94.Miller, W. W., 10.Milligan, W. O., 29.Milsom, D., 298.Milton, R. F., 283, 291.Mims, V., 234.Minard, F. M., 195.Minkoff, C. J., 135.Minot, G. R., 234.Minter, C.C., 299.Mitchell, H. K., 230, 233.Mitta, A. E. A., 194.Miyake, S., 22.Mizushima, S., 18, 228.Moo, 0. A., 190, 191, 194.Moeller, T., 270.Moffitt, W. E., 15.Moignard, L. A., 110.MolB, R., 90.Moncke, O., 87.Mondon, A., 200.Monroe, A. G., 94.Montignie, E., 108.Mookherji, A,, 41.Moon, K. L., 36.Mooney, R. C. L., 07, 70,Moore, C. V., 231.Moore, G;. E., 40, 41.Moore, J. A., 142, 145.Moore, R., 95.Moore, S., 216, 217.Moore, T., 252, 255, 258.Moore, T. E., 89.Moore, W. J., 90.Morf, R., 183.Morgan, McG. W., 199.Morgan, P., 155.Morino, Y., 18.Morley, W. G., 87.Morris, C. J. 0. R., 169, 170,Morrish, R. W. D., 36.Morrison, A. L., 200.Morrison, J., 297.Morrison, J. A., 28.Morrison, J. D., 23, 63.Morrison, L.W., 14.Morton, M. C., 25.Morton, R. A., 171, 180,181, 182, 183, 248, 249,261, 262, 263, 264, 266.79.171.2t51, 252, 255, 256, 257,Moskalev, P. V., 301.Moskow, M,, 9.Moss, J., 194.Mott, N. F., 27, 43, 53, 54.Mowat, J. H., 230.Mowry, D. T., 165.Mozingo, R., 140.Muelhouse, C. O., 289.Muller, A., 282.Mueller, G. P., 147.Muller, J., 155.Muller, R. H., 268, 298.Mukherji, D., 210316 IND$X OF AUTHORS' NAMES.Mukherji, S. M., 146.Mulcahy, M. F. R., 32.Mulley, H., 198.Mulliken, R. S., 14, 15.Munch-Petersen, J., 153.Murphy, R. K., 101.Murphy, W. P., 234.Murray, M. A., 141, 145.Muthanna, M. S., 16.Muxart, R., 104, 107.Naeser, C. R., 97.Nandi, X. .N., 119.Narayaswamy, P. K., 23.Nash, L. K., 293, 294, 297,Nast, R., 105.Natta, G., 20.Nebel, R.W., 115.Needham, J., 296.Nekrasov, B. V., 84.Neligh, R. B., 240.Nelson, A. L., 208.Nelson, E. M., 232.Nelson, F., 98, 99.Nelson, J. F., 158.Nesbitt, F., 107.Neuberger, A., 192.Neumann, A. L., 237.Neumann, E. W., 90.Newhall, W. F., 200.Newman, M. S., 142, 144.Nichol, C. A., 236, 237, 242.Nicholas, D. J. D., 11.Nichols, M. L., 273.Nicodemus, O., 148.Nicol, A., 102.Niedermeiser, R. P., 257.Niedrach, L. W., 108.Niel, P. B. van, 247.Nielands, T, B., 248.Nielsen, H. H., 13.Niemann, C., 192, 212, 213,Nier, A. O., 8, 89, 94.Nierenberg, W. A., 14, 295.Nijland, C. M., 80.Nikolaco, N. S., 283.Nilakantan, P., 41.Nilsson, H., 187.Nissan, A. H., 21.Nivard, R. J.F., 105.Nixon, I. S., 8.Nolle, A. W., 33.Noller, C. R., 164.Nolte, E., 200.Noonan, E. C., 11.Norberg, B., 91.Norris, L. C., 230, 240,Norris, L. D., 10.Norrish, R. G. W., 100.Northrop, J. H., 224.Novak, A. F., 237.Novick, A., 10.Nowotny, H., 25.Noyce, W. K., 282.301.220.NOY08, W. A., 31.Nozaki, K., 129.Nunn, J. R., 148.Nunn, I,. C. A., 165.Nyholm, R. S., 113.Nyman, C. J., 31.Nystrom, R. F., 141, 146.Obel, A. L., 258.Ochiai, E., 200.Ochsner, P., 178.O'Connor, R. T., 165.O'Doherty, K., 237.Ogg, C. L., 285.Ogstron, A. G., 125.Okazaki, H., 18.Oldbach, C. S., 297.Oldham, W. H., 154.Olin, S. M., 185.Oliver, G. D., 9, 17.Ollard, E. F., 50.Olshevsky, 5). E., 299.Olynyk, P., 191.Oncley, J. L., 224.Onstott, E.I., 91.Oosterhout, G. W. van, 18.Openshaw, K. T., 154,Oppliger, F., 284.Orchin, M., 90.Oriani, R, A,, 12.Orlamunder, E., 19.Orlemann, E. F., 99.Oroshnik, W., 175.Osborn, G. H., 270.Ospenson, J. N., 272.O'Sullivan, D. G., 171.Ott, W. H., 236.Otvos, J. W., 10.Overberger, C. G., 142.Overman, R. T., 289.Ovsyankina, N. A., 137.Owen, E. A., 23.Owen, G. E., 9.Owen, L. N., 130.Oxaal, F. 150.Pacault, A., 39.Pace, E. L., 9.Page, A., 236.Page, A. C., jun., 235.Page, J. E., 235.Pailer, M., 202, 203.Painter, E. P., 189, 190.Palfray, L., 158.Palir,, D. E., 85.Palmer, A. H., 214, 218.Palomaa, M. H., 125.Pandya, N. S., 276.Paneth, F. A., 9.Papa, D., 147, 155.Pappas, A,, 108.Pariser, R., 32.Parker, L.F. J., 234, 235.Parker, R. H., 301,Parker, W. G., 94.195, 202, 206, 2G7.Parks, W., 33.Parmerter, S. M., 194.Parrott, €3. M., 230.Parshad, R., 20.Partington, J. R., 96, 104.Partridge, M., 195.Partridge, S. M., 121.Partridge, W. S., 296.Pascal, P., 39.Patel, D. K., 177.Patel, J. C., 240.Paterson, S., 9.Pathak, P. D., 8.Patrick, R. L., 192.Patty, F. A., 303.Paul, W. J., 237.Pauling, L., 42, 45, 47, 48,49, 50, 51, 53, 54, 55, 66,68, 69, 72, 76, 79, 245,300.Pausacker, K. H., 208, 209.Pavlic, A. A., 140.Pavlov, A. M., 157.Peacock, R. D., 111.Pearson, B. L., 41.Pearson, T. G., 100.Pease, R. N., 95.Peeling, E. R. A., 131.Peiser, H. S., 82, 101.Pellam, J. R., 8, 20.Peltier, S., 269.Penin, N., 19, 21.Penner, S.E., 179.Penny, G. F., 188.Penrose, R. P., 41.Pepinsky, R., 60.Pepkowitz, L. P., 303.Pepper, H., 255.Peretz, W. L., 188.Perkin, W. H., 208.Perley, G. A., 299.Perlman, I., 87, 291.Perlman, M. L., 304.Pernet, J. C., 104.Perreu, J., 28.Perros, T. P., 97.Perry, R. H., 145.Perutz, M, F., 58.Peschanski, (Mme.) D.,Pesez, M., 273, 283.Peshkov, V., 8.Pesmatjoglou, S., 28.Petermann, M. L., 223.Peters, C. C., 66.Peters, E. D., 280.Petersen, S., 150.Peterson, R. F., 218.Peterson, W. H., 230.Petrov, A. A., 129.Petrov, A. D., 157.Petrow, V., 174, 235.Pett, L. B., 183.Pfanner, D. E., 284.Pfister, K., 188.Pfister, R. J., 279.107ENDEX OF AUTHORS’ NAMES. 317Phibbs, M. K., 32.Phillips, D. M.P., 223.Phillips, G. O., 103.Phillips, H., 119, 121.Phillips, L. B., 191.Phillipson, J. M., 160.Phipps, T. E., 304.Pickels, E. G., 261.Pickford, R. W., 260.Pierce, C., 28.Pierce, H. B., 256.Pierce, J., 234, 236.Pierce, J. V., 235.Pierre, 166.Pieters, H. A. J., 293, 297,298, 299.Pietrusza, E. W., 188, 191.Pikl, J., 201.Pilgrim, F. J., 194.Pinckard, J. H., 244, 246.Pinder, A. R., 201.Pink, R. C., 17.Pinkus, A. G., 145.Pino, F., 273.Pirie, N. W., 211, 213.Pitt, G. J., 61.Pittman, E. W., 108.Pitzer, I(. S., 18, 94.Plati, J. T., 174, 176.Platt, B. C., 119.Platt, J. R., 14.Plattner, P.A., 144,145,164.Plazin, J., 282.Plessier, M., 255.Ploquin, J., 15.Poirier, P., 283.Polanyi, M., 116, 117, 118.Polchlopek, S.E., 112.Polgar, A., 244, 245, 246,Polgar, N., 161, 162.Polglase, W. J., 195.Polis, B. D., 213, 214.Pollard, E., 285, 290.Pornmer, H., 174.Pond, T. A., 13.Ponndorf, 172.Poole, H. G., 131.Popescu, B., 282.Popkin, A. H., 117.Poplett, R., 119.Popowsky, M., 304.Popper, H., 257, 258.Porter, M. W., 235.Porter, R. R., 218, 221.Porter, W. L., 285.Portmann, P., 143.Porsehinski, K., 203.Potter, R. L., 109.Powell, A. R., 89.Powell, E. O., 122.Powell, H. M., 85.Powles, J. G., 22.Praagh, G. van, 9.Prelog, V., 150, 151, 153,247.203, 204, 207, 210.Preobrazhenskii, N. A., 170Prescott, C. H., 297.Prestwood, R. J., 96.Prevost, C., 121.Ptibil, R., 275.Price, C. C., 125, 151, 155.Price, J. R., 210.Price, T.D., 10.Price, V. E., 186.Price, W. B., 295.Price, W. C., 14, 95.Price, W. J., 22.Priest, H. F., 16, 109.Prigogine, I., 7, 8.Prince, W. C., 14.Prim, D, A., 144.Printy, H. C., 143, 205.Pritchard, J. A., 237.Probst, R. E., 8, 89.Prochhzka, J., 153.Prokhorov, P. S., 28.Prosen, E. J., 17.Prosternik, M., 160.Proud, E. R., 303.Prout, F. S., 160, 162.Provasoli, L., 238.Prue, J. E., 30.Pryor, M. J., 111.Pullman, A., 15.Pullman, B., 11, 15, 17, 18,Purse, J. H., 292.87.Quellet, J., 200.Quiggle, D., 278.Quill, L. L., 97.Quilliam, J. P., 261.Quintin, M., 11.Qurashi, 33. M., 61.Rabi, I. I., 14.Rachele, J. R., 190.Rachford, H. H., 29.Radimer, K. J., 283.Radosavljevic, S. D., 94.Riitz, R., 105.Ragsdale, J.W., 153.Raistrick, B., 105.Rajogopal, K. R., 252, 258.Rajoport, H., 199.Raley, J. H., 32.Ralf, E., 92.Raman, Sir C. V., 23.Ramanathan, I<. G., 23.Ramsdell, L. S., 66.Randolph, C. L., 95.Rank, D. H., 18, 277, 278,Ransley, C. E., 293, 297.Rao, B. S. V. R., 270.Raoul, Y., 255.Raper, R., 143, 199.Raphael, R. A., 165, 166.Rapport, M. M., 192.Rapson, W. S., 148.Rasurvajew, G., 37.279, 280.Rathjens, G. W., 94.Rathmann, F. H., 249.Ratterman, B. J., 295.Ravel, J. M., 238, 242.Ravve, A,, 189.Rayman, D. E., 141.Raymord-Hamet, 203, 204.Rayner, J. H., 85.Razouk, I., 93.Rea, J. L., 255.Redlich, O., 277.Reed, R. I., 131, 135.Reed, S. A., 271.Reekie, J., 41, 44.Rees, A. L. G., 298.Rees, M. W., 213, 214, 216.Register, U.D., 237, 243.Rehner, T., 88, 98.Reichstein, T., 130, 142,Reid, A. F., 10.Reid, J. C., 192.Reimann, F., 243.Rein, H., 300.Reisner, D. B., 140.Remington, R. E., 256.Renes, P. A., 23, 74.Renfrow, W. R., 154.Renoll, M. W., 142, 144.Rescorla, A. R., 298.Reuter, F. H., 101.Reuter, F. W., 297.Reynolds, B., 284.Reynolds, J. G., 298.Reynolds, S. A,, 289.Reynolds, T. M., 208.Rhodes, R. G., 73.Rice, B., 95.Rice, C. N., 304.Richards, P. I., 14.Richards, R. B., 33.Richards, R. E., 9, 33.Richards, W. T., 20.Richardson, R. W., 177,Rickes, E. L., 234, 235,Riedel, L., 21.Riegel, B., 154.%eman, W., 283.Ftigamonti, R., 24.Ziley, D., 224.Wey, H. L., 23.tiley, R., 300.Zing, H., 13, 14.Zing, M.F., 271.tingler, B. I., 154.tisler, T., 100.Eitchie, E., 196.Eivers, J. T., 174.tobblee, A. R., 236, 237.Eoberts, A,, 13.toberts, C. W., 142.Eoberts, I., 123.toberts, I. Z., 239.Eoberts, J. D., 129, 141.202.178.236318 1Roberts, J. K., 34.Roberts, J. S., 17.Roberts, L. E. J., 297.Roberts, R. B., 239.Roberts, R. M., 222, 223.Robertson, A., 32, 285.Robertson, J. M., 16, 23,Robertson, P. W., 138.Robertson, W. W., 14.Robeson, C. D., 168, 169,Robinson, C. A,, 188.Robinson, E. S., 10.Robinson, P. L., 100, 111.Robinson, Sir R., 114, 151,152, 154, 161, 162, 163,195, 196, 197, 201, 203,207, 208, 209, 210.Roche Products, Ltd., 174.Rodebush, W. H., 14.Rodewald, B., 93.Rogers, A. O., 191.Rogers, M. T., 81,Rogers, V., 296.Romers, C., 79.Romo, J..141.Ronco, A., 140, 169, 173,Ronso, M., 102.Rooksby, H. P., 26, 72.Rose, A., 303.Rosen, G. D., 248.Rosen, L. J., 117.Rosenbaum, E. J., 278,279.Rosenberg, H. R., 154.Rosenblum, C., 182.Rosenheim, O., 185.Rosenkranz, G., 141.Rosenstein, R. D., 108.Ross, S. D., 115, 125.Ross, W. C. J., 122.Rossini, F. D., 17, 280.Roth, D. A,, 159.Roth, W. A., 94.Roth, W. L., 79.Rothaan, C. C. J., 14, 15.Rothchild, S., 142, 148.Rottenberg, M., 206.RouvCj, A., 150.Rowe, E., 301.Rubin, L. J., 168.Rubin, M., 235, 236.Rubtsov, I. A., 170.Ruckstuhl, P., 274.Rudorff, W., 71, 108.Ruegger, A,, 170.Ruegamer, W. R., 237.Rust, F. F., 32.Ruff, O., 111.Rulfs, C. L., 268.Rundle, R.E., 12, 24, 25,55, 67, 68, 88, 113.RUSS, J. J., 130.Russell, M. B., 302.Rmsell, W. C., 257, 258.62, 63, 83, 103.174, 175, 252.249.DEX OF AUTHORS' NAMES.Ruston, W. R., 108.Rutherford, E., 286.Ruzhentseva, A. K., 283.Ruzicka, L., 142, 164.Ryan, D. E., 271.Ryan, F. J., 214.Ryden, T., 145.Rydon, H. N., 122, 194,Rytina, A. W., 148.Sack, H,, 276.Safford, H. W., 284.Sagane, R., 290.Sahami, N., 187.Sahney, R. C., 38, 40.Saidel, L. J., 214.Sailer, E., 186.St. George, R. C. C., 261.Saito, Z., 260.Sakal, E., 173, 174.Salah, M. K., 181, 262.Salmon, W. D., 232.Salomon, I., 144.Salvioni, E., 269,Sampath, A., 231.Sampey, J. R., 143.Samson, S., 74.Samuelsen, E., 150.Sandorfy, C., 15.Sandoval, A., 244, 246.Sands, M., 239.Sanger, F., 219.Santen, J.H. van, 73.Sasaki, H., 50.Sato, Y., 10.Sauberlich, H. E., 232, 233.Sauer, C. W., 141.Sauer, J. C., 148.Saunder, D. H., 25.Saunders, B. C., 189.Saunders, J. H., 150.Saunders, K. W., 296.Saunders, T. G., 131.Savage, J. P., 252.Savchenko, G. S., 106.Savinkova, E. I., 301.Sawyer, K. F., 28.Sayles, C., 190.Sayre, D,, 85.Scaife, J. F., 138.Schade, D., 155.Schaefer, A. E., 231, 240.Schlifer, H., 111, 273.Schiifer, K., 7, 8, 11.Schafer, J. G., 141.Schaffer, F. L., 269.Schaffner, J. G., 294.Schallamach, A., 21Schechter, W. H., 90.Scheffer, F. E. C., 294.Schein, A. H., 190.Schenk, G. O., 32.Schepartz, A. I., 142.Scherhaufer, A., 71, 108.Schick, E., 171, 177.226.Schiessler, R.W., 148.Schindler, O., 237.Schlagl, K., 198.Schlenk, W., 156.Schlesinger, H. I., 95.Schlientz, W., 142.Schlittler, E., 143, 155, 201,204, 206, 210.Schmid, H., 143, 145.Schmid, K., 228.Schmidle, C. J., 151.Schmidt, H., 30.Schmitz-Dumont, O., 102.Schneider, A., 122.Schneider, A. K., 162.Schneider, E. E., 264.Schneider, P., 181.Schneider, V. von, 278.Schneider, W. C., 21.Schnider, O., 200.Schober, R., 23.Schoberl, A., 189.Schoental, R., 15.Schopf, C., 195, 196.Scholander, P. F., 294, 295,Scholz, C., 203, 204.Schomaker, V., 83, 103.Schoone, J. C., 58, 206.Schramm, C. H., 225, 226.Schramm, R., 135.S3hrenk, W. G., 165.Schuerch, C., 176.Schuette, H. A., 159.Schutzner, W., 42.Schuhmann, P.J., 273.Schukina, M. N., 170.Schuler, R. H., 287.Schull, C. G., 22.Schultz, L., 257.Schumacher, A. E., 230.Schumb, W. C., 16, 95, 106,Schuster, K. H., 190.Schwab, G. A., 28.Schwab, G.-M., 37.Schwartz, S. O,, 231.Schwarz, N., 300.Schwarzenbach, G., 273,Schwarzkopf, O., 142, 169,Schweitzer, G. K., 270.Schwenck, A., 283.Schwenk, E., 147, 155.Schwinger, J., 14.Schwyzer, R., 176, 184.Scott, A. B., 107.Scott, A. D., 122.Scott, E. J. Y., 15.3cott, N. D., 191.Scott, P. A. A., 187.Scott, R. W., 278.Scott, T. R., 96.Seaborg, G. T., 87, 285,289, 290, 291.296.109, 283.274.172INDEX OF AUTHORS’ NAMES. 319Sealock, R. R., 192.Searle, C. E., 119.Seel, F., 30, 107.Segel, E., 135.Segr6, E., 111.Seguin, M., 38, 39.Seifert, €4.L., 304.Seijo, E., 162.Seitz, F., 44.Seitz, K., 177.Sekito, S., 50.Sell, K., 125.Selwood, P. W., 34, 35, 38,39, 88, 89.Semb, J., 230.Seren, 288.Sevigne, F. J., 252.Seward, R. P., 90.Sexton, E. L., 255.Seymour, D., 122.Shabica, A. C., 188, 194.Ghaffer, P. A., 23.Shand, W., 80.Shantz, E. M., 168, 175,176, 177, 180, 181, 183,184, 252.Sharman, I. M., 249.Sharp, A. E., 232.Sharpe, A. G., 109.Shaver, F. W., 149.Shaw, G. E., 238.Shaw, J. A., 92.Shaw, P. F. D., 11.Shcherbakova, K. D., 285.Shea, R. C., 14.Sheehan, J. C., 195.Shehata, O., 233.Shekleton, J. F., 187.Shellard, A. D., 26.Shelton, J. P., 25.Shen, C. C., 177.Shen, S. C., 296.Shepherd, M., 291, 292,Sheppard, N., 18.Sherk, K.W., 157, 159.Sherman, M., 258.Sheveleva, N. B., 281.Shigata, J., 290.Shinowara, G. Y., 165.Shirakawa, H., 278.Shirley, R. L., 282.Shishido, K., 283.Shive, W., 238, 240, 242.Shorb, M. S., 237, 238.Short, F. A., 145.Short, W. F., 199.Short, W. S., 143.Shorter, J., 116.Shtutser, V. V., 84.Shuey, P. McG., 283.Shukers, C. F., 232.Shunk, C. H., 152.Shurmovskaya, N., 300.Siddhanta, S. K., 38.Siebert, H., 13.298.Siefken, W., 150.Siggia, S., 293.Signer, R., 158.Silberstein, H. E., 191.Silbiger, G., 12.Sillen, L. G., 30, 74, 82, 94.Simanouti, T., 18, 228.Simard, R. G., 302.Simmers, M. G., 138.Simmons, J. W., 13.Simon, F., 37.Simon, P., 102.Simonsen, S. H., 272.Simpson, 0. C., 304.Singh, M., 38, 40.Sirur, M.V., 16.Sixma, F. L. J., 39, 139.Sjoberg, K., 258.Skapski, A. S., 19.Skeggs, H. R., 238.Skinner, H. A., 17, 18, 19.Skinner, J., 277.Slabey, V. A., 141.Slack, R., 194.Slater, S. N., 148, 163, 164.Slates, H. L., 142, 171.Sloatman, W. S., 156.Slocombe, R. J., 150.Slonick, M., 14.Small, L. A., 109.Smedley-MacLean, I., 165.Smith, A. G., 13.Smith, A. L., 108.Smith, A. W., 39.Smith, C. L., 256.Smith, C. W., 185.Smith, D. P., 24.Smith, E. L., 186, 195, 216,Smith, G. F., 206, 272, 273.Smith, H. A., 140.Smith, H. M., 301, 303.Smith, J. D. M., 298.Smith, J. H., 112.Smith, J. H. C., 246, 247.Smith, M. E., 97.Smith, P., 130, 176.Smith, R. N., 28, 294.Smith, V. R., 257.Smith, W. B., 13.Smith, W.H., 284.Smith, W. T., 111, 272.Smith, W. V., 13.Smittenberg, J., 304.Smook, M., 145.Smyth, C. P., 12, 21.Smyth, I. F. B., 155.Snell, A. H., 10.Snell, E. E., 230, 233, 238,Snook, G. F., 235.Snow, S., 258.Snyder, H. R., 151, 152,Snyder, H. S., 14.Snyder, P. E., 109.234, 235, 236, 238.239.185, 187, 193, 194.Sobel, A. E., 258.Sobotka, H., 142, 169, 178,Sorensen, J., 157.Sorensen, N. A., 150, 157,Sorensen, S. P. L., 212.Soffer, M. D., 157, 159.Soldate, A. M., 68, 84.Soller, A., 292.Solomon, A. K., 107.Solovov, A. P., 300.Somersalo, A., 92.Somsiya, T., 304.Sondheimer, F., 140, 166,173, 177, 179.Soos, I., 292.Sorm, F., 199.Sorum, H., 78.Souchay, P., 275.Spath, E., 199, 201.Spakowski, A. E., 271.Speakman, J., 82.Specht, E.H,, 135.Specter, M. E., 192.Spedding, H., 16.Speeter, M. E., 142.Speiser, R., 93.Speitel, R., 204.Spence, R., 87, 296.Spence, R. W., 10, 301.Spencer, C. F., 211.Sperling, E. O., 292.Spcro, G. B., 141.Spiegler, K. S., 112.Spielman, M. A., 161, 162.Spies, J. R., 217.Spies, T. D., 231, 232, 240.Spinks, A., 169.Spinks, J. W. T., 10, 31.Spooner, C. E., 281.Sprague, C. A., 292.Sprague, P. T., 292.Sprague, R. H., 14.Sprecher, P., 158.Springall, H. D., 10.Sprince, H., 231.Spryskov, A. A., 137.Squire, C. F., 8.Squires, P., 28.Squitieri, E., 109.Srisukh, S., 248.Sroog, C. E., 145.Staats, F. C., 284.Stacey, M., 156.Stackelberg, M. von, 102.Stacy, R. W., 298.Stadler, H. P., 83.StSIIberg-Stenhagen, S.,Stamm, R.F., 277, 278,Stanley, C. W., 87.Staple, E., 294, 299.Starr, C. E., 298.Staveley, L. A. K., 12.179.166.157, 169, 161, 162.279320 INDEX OF AUTHORS’ NAMES.Steacie, E. W. R., 31.Steams, R. S., 29.Steenhauer, A. J., 210.Steens, J. van, 157.Steensholt, G., 21.Stegeman, G., 95.Steger, A., 166.Stehr, E., 282.Stein, J. A., 292.Stein, W. H., 216, 217.Steiner, R., 273.Steinkamp, R., 232.Stene, J., 166.Stener, H., 196.Stenhagen, E., 157, 158,161, 162.Stephanon, S. E., 90.Stephen, A. M., 210.Stephen, J. M. L., 223.Stephenson, O., 174.Stern, E. S., 31, 125, 126.Stern, J. R., 258.Stettiner, H. M. A., 112.Steven, D. M., 247.Stevens, C. D., 295.Stevens, T. S., 201.Stevens, W.H., 10.Stevenson, D. P., 10.Steyermark, A., 280, 284.Stiller, R. C., 235.Stillson, G. H., 280, 282.Stites, J. G., 97.Stokstad, E. L. R., 229,230, 231, 233, 234, 235,236, 238.Stoll, A., 142.Stoll, M., 149, 150.Stone, R. E., 232, 240.Stoneburner, W. S., 165.Stork, G., 147.Stosick, A. J., 31.Stott, G., 38.Stover, C. S., 296.Stragand, G. L., 284.Strain, H. H., 244.Strandberg, M. W. P., 13.Strating, J., 157.Straub, E., 245, 246.Straumfjord, J. V., 258.Strauss, N. S., 159.Strauss, TJ. P., 29.Strong, F. M., 165.Stroupe, J. D., 108.Stuart, R. G., 284.Stubbs, A. L., 181,251,252,Stubbs, 3’. J., 136.Stumper, R., 93.Suarez, R. M., 232, 240.Suarez, R. M., jun., 232.Subba Row, Y. J., 230,231.Sue, P., 11.Suess, H.E., 87.Sugden, S., 11, 30, 40, 96,Sugden, T. M., 28, 300.262, 263.119.Sugita, T., 228.Sullivan, A. P., 299.Sultanbawa, M. U. S., 130.Sumner, E., 245.Suter, C. M., 185, 193.Sutherland, G. B. B. M.,Sutherland, J. E., 242.Sutherland, L. H., 156.Sutton, G. J., 96.Sutton, J., 99.Sutton, L. E., 66, 83.Sutton, T. B., 258.Sutton, T. C., 294.Suyver, J. F., 139.Svedberg, T., 212.Svirbely, W. J., 112.Swain, C. G., 115, 116, 125.Swamer, F. W., 153, 154.Swan, G. A,, 143, 204, 205.Swann, S., 91.Swarc, M., 16.Swendseid, M. E., 232, 233,Swidinsky, J., 142, 169,Swinnerton, A. C., 9.Sydoriak, S. G., 89.Synge, R. L. M., 185, 195,Syrkin, J., 15.Szabo, Z., 97, 292.Szasz, G. J., 9, 18, 28.Szumszkovicz, J., 160.Taboury, F.J., 276.Tagtstrom, B., 162.Taher, N. A., 115.Tailby, S. R., 96.Ta-Kong Liu, 14.Talbot, J., 27.Tanaevsky, O., 42.Tanenayev, I. V., 106.Tang, V. W., 244.Tani, H., 225.Tanis, H. E., 301.Tansley, K., 261.Taras, M., 273.Thrnoky, A. L., 119.Tatlow, J. C., 156.Taube, H., 110.Tauber, 0. E., 248.Taylor, E. G., 30, 103.Taylor, H. A., 296.Taylor, H. F., 297.Taylor, H. S., 10, 34.Taylor, M. W., 257, 258.Taylor, T. W. J., 211.Taylor, W. I., 210.Taylor, W. J.: 17, 203.Tchakirian, A., 39.Tedder, J. M., 156.Tekman, S., 218.Teller, E., 87.Temple, R. B., 227.Terem, H. N., 105.226, 227.234.172.219.Terentev, A. P., 285.Ternberg, J. L., 243.Teston, R. D., 283.Tewksbury, C. I., 91.Thsler, L., 279.Thewlis, J., 50.Thiers, R., 270.Thirion, P., 21.Thode, R., 87.Thode, H.G., 90, 106.Tholin, G., 27.Thomas, H. C., 97.Thomas, J. H., 32.Thomas, L. A., 9.Thomas, L. B., 31.Thomas, M. D., 300.Thomas, P. R., 293.Thomas, W. D. E., 11.Thomassin, R., 276.Thompson, A. F., 171.Thompson, H. T., 243.Thompson, H. W., 14, 33,149, 235, 279, 301.Thompson, J. K., 90.Thompson, R., 30.Thompson, R. C., 11.Thompson, S. Y., 248, 256.Thomson, R., 104.Thomson, R, H. K., 119.Thorn, G. D., 103.Thorn, J. H., 22.Thudichum, J. L. W., 185.Thiilo, E., 105.Tilston, D. V., 39.T’ing-Sui Ke, 27.Tiselius, A., 223.Tishler, M., 142, 171, 182,Tisza, L., 8.Titov, A. I., 135.Titus, H. W., 235.Tobias, C. A., 289.Tobiyama, T., 278.Todd, A.R., 201.Todd, B. J., 94.Todd, D., 147.Tolman, R. C., 7.Tolun, R., 109.Tomassi, W., 9.Tomita, M., 202.Tomlinson, J. W., 29.Tompkins, F. C., 28, 297.Toogood, J. B., 177, 178.Topley, B., 105.Torbet, N. J., 231, 237.Tordai, L., 285.Torrey, H. C., 41.Totter, J. R., 194, 232.Tourky, A. R., 109.Tovborg-Jensen, A,, 58.Townes, C. H., 13, 14.Trail, M. D., 159.Traynard, P., 278, 279.Treitel, O., 33.Trevoy, L. W., 141, 146.Trinh, N. Q., 130.188, 189, 193, 194INDEX OF AUTHORS’ NAMES. 32 1Trivelli, G., 130.Troitskii, G. V., 183.Truant, A. P., 256.Truter, M. R., 83, 103.Tscherniaeva, J. I., 283.Tsuboi, M., 228.Tuemmler, F. D., 280.Tufts, L. F., 283, 294.Tullar, B. F., 153, 185, 186.Tunca, M , 218.Tunnicliff, D.D., 280.Tuppy, H., 199.Turba, F., 190.Turkel, S. H., 288.Turkevich, J., 34.Turner, N. C., 304.-Turner-Jones, A., 82, 101.Tuschen, E., 207.Tyran, L. W., 191.Tyrrell, H. J. V., 8.Ubbelohde, A. R., 9, 12, 17,Ubeda, F. B., 271.Udenfriend, S., 216.Uffer, A., 143.Uhle, F. C., 141.UltQe, A. J., 129.Underhill, E. J., 151.Underwood, G., 144.Ungley, C. C., 240, 243.Unterzaueher, J., 284.Urey, H., 11.Uri, N., 106.U.S. Atomic Energy Com-mission Report, 98, 99.U.S. Bureau of Mines, 293.Valdescasas, F. G., 256.Valley, G. E., 111.Van Arkel, A. E., 89.Vand, V., 61.Vandoni, R., 104, 293.Van Ess, P. R., 171.Vanselow, C. H., 270.Van Slyke, D. D., 282.Vasenin, F. M., 108.Vaughan, W. E., 32.Vayda, L.L., 292.Velick, S. F., 160, 162, 163.Velluz, L., 273.Vengerov, M., 303.Venkataramaniah, M., 2 70.Venkateswaran, C. S., 276.Verkade, P. E., 167.Vermeer, J., 157.Vernier, M.-L., 261.Verwey, E. J., 21, 73.Vestin, R., 92.Vet, A. P. van der, 278.Vicary, D. R., 136.Vickery, H. B., 213.Vickery, R. C., 97.Viloteau, J., 26.Vinet, A., 183, 184, 255,18, 22, 26.266.REP.-VOL. XLVI.Vint, W. D., 291.Vleck, J. H. van, 41.Vold, R. D., 160.Vole, B. W., 258.Volk, H., 19.Volkenburgh, R. V., 141.Volkoff, G., 87.Vonnegut, B., 28.Voter, R. C., 271, 272.Vousden, P., 22.Vozza, J. F., 154.Vroege, A. K., 167.Vul’fson, N. S., 170.Wache, X., 269.Wacker, P. F., 99.Wadsworth, K. D., 136.Wagman, D. D., 280.Wagner, A., 189.Wagner, C., 24.Wagner, C.D., 10.Wagner, E. C., 284.Wagner, G., 292, 298.Wagner, R. B., 142, 145.Wagner-Jauregg, T., 161.Wahl, A. C,, 96.Waight, E. S., 121, 130.Wald, G., 182, 245, 246,249, 261, 262, 265, 266,267.Waley, S. G., 226.Walker, G. B., 154.Walker, I. K., 271.Walker, N., 192.Wallace, J. M., jun.> 160.Wallenfals, K., 247.Waller, C. W., 230.Walling, C., 10.Wallis, E. S., 155.Walls, I. M. S., 174.Walsh, A. D., 236.Walter-LQvy, (&he.) L.,Walton, W. W., 284.Wang, Y. L., 258.Ward, R., 108.Ware, E., 271.Warhurst, E., 18.Warncke, R., 102.Warner, D. T., 190, 191,Warner, R. C., 224.Wartik, T., 95.Wmastjerna, J. A., 24.Waser, P., 143.Wassink, E. C., 246.Wataghin, G., 87.Watanabe, I., 18.Waterman, H.I., 157.Waters, W. A., 32, 110, 285,Watson, H. B., 115, 119.Watson, J,, 226.Watt, G. W., 103, 109, 113.Watts, R. J., 13.Waugh, D. F., 211.93.194.291.Way, K., 288.Weaver, E. R., 300.Webb, L. J., 210.Weber, K., 108.Weber, R., 299.Wechsler, M. T., 99.Weedon, B. C. L., 128, 140,170, 173, 176, 177, 178,179.Week, F., 252.Weidner, R. T., 13.Weil, R. A. N., 148.Weimann, J., 278.Weinhouse, S., 10.Weisblat, D. I., 152, 169,Weisenberger, E., 285.Weisler, L., 168, 175, 252.Weiss, J., 106.Weiss, P. R., 41.Weiss, Z., 174, 176.Weissler, A., 20.Weissmann, 5. I., 27.Weitkamp, A. W., 156,Welch, A. D., 232, 237.Wellard, H. J., 22.Wells, A. F., 19, 58, 66, 74,Wender, I., 90.Wendler, N.L., 142, 171,Wendt, H., 104.Wennesland, R., 293.Wentink, T., 13.Werner, A. E. A., 101.Werner, L. B., 100, 269.Wert, C. A., 27.West, R., 240.West, S. S., 304.Westheimer, F. H., 119,132, 135.Weston, A. W., 142.Westrik, R., 17.Westnun, E. F., 64.Wethington, K., 89.Whetstone, J., 24.Whiffen, D. H., 149.Whipple, G. H., 191.White, F. L., 14,White, J. G., 62, 63.White, J. U., 302.White, L. M., 245.White, W. B., 9.Whitehair, C. K., 231.Whitehouse, H. S., 142.Whitely, A. H., 296.Whitmer, C. A,, 41,Whitmore, F. C., 117, 148,Whitmore, F. E., 83, 104.Whitney, J., 13, 105.Whittaker, A. G., 105.Whittaker, E. J. W., 78.Whynes, A. L., 104.Wiame, 5. M., 8.186, 249.162.80, 91.182.156.322 INDEX OF AUTHORS’ NAMES.Wibaut, J.P., 139, 146,Wiberg, E., 16, 89, 95.Wichterle, O., 153.Wicke, E., 109.Wickman, F. E., 79.Wicks, R., 119.Widmer, W., 164.Wiegand, R. V., 278, 279,Wieland, H., 209.Wiener, H,, 17.Wiese, C. F., 255, 256.Wiggin, E., 294.Wigner, E., 44.Wiig, E. O., 11.Wilds, A. L., 152.Wiley, R. H., 143, 188.Wilk, M. B., 107.Wilkinson, J. F., 232, 241.Willard, G. W., 20.Willard, H. H., 270.Willenborg, W. J., 299.Willi, A., 274.Williams, C., 295.Williams, C. D., 136.Williams, D., 13.Williams, E. F., 213, 214.Williams, G., 131, 132.Williams, K. T., 245.Williams, L. R., 189.Williams, M.. D. A., 92.Williams, N. E., 182.Williams, R. J., 230.Williams, R. J. P., 274.Williams, R. R., 87, 287.Williams, R. W., 23.Willis, F. H., 20.Willits, C. O., 285.Willmer, E. N., 260.Wills, J. H., 181.Wills, L., 230.Wilsdorf, H., 83.Wilson, A. A., 257.Wilson, A. J. C., 58, 61.Wilson, A. S., 67, 68.Wilson, C. L., 122, 298.Wilson, C. V., 161.Wilson, E. B., 13.Wilson, K. M., 291.Wilson, L., 143.Wilson, W., 185.Winkler, H. G. F., 76, 77.Winkler, L. T., 300.Which, T., 223.198, 203.280.Winslow, E. H., 102, 301.Winsor, R. V., 12.Winstein, S., 122, 129, 131.Winsten, W. A., 238.Winter, H. J., 157.Winter, J., 33.Winzler, R. I., jun., 193.Wirtz, K., 12, 33.Wise, E. C., 169, 187, 249.Wise, P. H., 141.Wiseman, E. L., 105.Witkop, B., 141, 203, 204,Wittkop, I., 30.Wittle, E. L., 117.Wohlers, H. C., 173.Wohlhuter, (Mlle.) M., 98.Woislowski, S., 191.Wolbach, S. B., 258.Wolf, D. E., 235.Wolf, G., 12.Wolfenden, J. H., 19.Wolf€, L. K., 183.Wolff, P., 10.Wolfhard, H. G., 32.Wolfrom, M. L., 185, 284.Wolny, J., 96.Wood, H. C. S., 202.Wood, J. L., 189.Wood, J. R., 166.Wood, T. R., 234, 235,Woodburn, H. M., 145.Woodruff, C. W., 233.Woodruff, H. B., 238.Woodward, I., 12, 22, 26.Woodward, L. A., 279.Woodward, R. B., 154, 197,204, 205, 208, 225, 226.Woods, L., 295.Woodside, &I. R., 252.Woolf, L. I., 115.Woolley, D. W., 231.Wooster, C. B., 146.Wooster, N., 9.Wooster, W. A., 9.Wooten, W. C., 143.Wright, B., 30.Wright, B. D., 13.Wright, D. F., 165.Wright, E. R., 270.Wright, H. F., 173, 174.Wright, L. D., 238.Wright, W. D., 260, 266.Wrinch, D. M., 212..205, 206.236.Work, E., 184.Wuest, H. M., 142, 169,Wulff, I., 294.Wyart, J., 9.Wyckoff, R. W. G., 58.Wynne-Jones, W. F. K.,172.106.Yaffe, L., 10, 87.Yagi, H., 283.Yamamoto, R., 175.Yamaguchi, S., 18.Yang, J. T., 98.Yankwich, P. E., 87.Yashin, V, N., 28.Ya-Turkan, E., 301,Yeo, D., 41.York, H. F., 10.Yost, D. M., 105, 107.Yost, R. S., 154.Young, D. M., 297.Young, F. G., 149.Young, G. H. S., 32.Young, H. S., 29.Young, R. C., 106.Young, T. F., 95.Young, W. G., 129,170.131,Zachariasen, W. H., 23,64, 65, 66, 68, 69, 70, 73,75, 76, 79, 97.Zambito, A. J., 188, 193.Zandt, G. van, 14.Zaugg, H. E., 285.Zavoisky, E., 40.Zechmeister, L., 168, 244,245, 246, 247.Zeile, K., 174, 175.Zeiss, H., 9.Zeiss, H. H., 122.Zellars, G. R., 153.Zener, C., 27.Zhukhovitsky, A. A., 19.Ziegler, K., 149.Zimens, K. E., 24.Zimmermann, M., 153.Zimmerschied, W. J., 156.Zirkle, C. L., 188.Zook, H. D., 153.Zorin, N. I., 108.Zubris, A,, 183.Zucker, L. M., 236.Zucker, T. F., 236

ISSN:0365-6217    

DOI:10.1039/AR9494600305

出版商:RSC    

年代:1949

数据来源: RSC

摘要:

INDEX OF SUBJECTS.Acenaphthene, dipole moments of, 16.Acetic anhydride, conducting solutions ofsalts in, 30.Acetic anhydride, trifluoro-, as catalyst foresterification, 155.Acetomesitylene, reduction of, 141.Acetoxonium ion, 123.Acetyl groups, determination of, 284.Acetylene, compounds of, with copper andAcetylenic compounds, reduction of, 147.Acetylcyclopropane, reduction of, 141.Acid chlprides, preparation of, 166.Acids, carboxylic, aliphatic, synthesis of,159.silver salts, halide formation from,154.tertiary, 163.olefinic, 164.organic, reduction of, 142.unsaturated, 164.Acronychia baueri, 210.Acronycidine, 210.Acronycine, 210.Acrylonitrile, reactions of, 150.Acrylonitrile, a-hydroxy-, a-acetyl deriv-Actinium, separation of, from lanthanum,Actinon sulphides, crystal structure of,Actinons, 88, 96.Adsorbed substances, magnetic propertiesof, 35.Adsorption, 28.Aerosols, physical chemistry of, 28.“ Affinin,” 166.Afwillite, crystal structure of, 78.Ajmaline, 210.j?-Alanine, preparation of, 187.Albumin, serum, copper binding by, 33.Alcohols, aliphatic, synthesis of, 158.polyene, preparation of, 179.tertiary, esters, hydrolysis of, 121.Aldehyde, CI4, 173.Aldehydes, photochemistry of, 31.Aldimines, reduction of, 146.Aldol condensation, 150.Aliphatic compounds, long-chain, 156.Alkali metals, ammonia solutions of, 31.silver, 92.determination of, 293.ative, 149.98.70.chemistry of, 97.perborates, 96.selenochromites, crystal structure of,thiochromites, crystal structure of, 7 1.Alkaline-earth carbonates, solid solutionsmetals, ammonia solutions of, 31.71.of, 24.Alkaloids, acridine group, 210.biogenesis of, 195.Chelidonium, 20 1.Daphnandra, 20 1.indole group, 203.lupinane group, 199.quinazolone group, 210.isoquinoline group, 200.Xtrychnos, 206.yohimbine, 197, 203.Alkyl halides, replacement reactions of,Alkylbenzenes, chlorination of, 139.Alkyloxy-groups, determination of, 284.Alloys, structure of, 51.Ally1 esters, alkaline hydrolysis of, 120.Allylic halides, anionotropy in, 130.rearrangement in nucleophilic substitu-tion, 125.Aluminate ion, 96.Aluminium, magnetic susceptibility of, 41.Aluminium trichloride, crystal structurefluoride, preparation and propsrties of,115.theories of, 42.of, 74.96.Americium, ion radii for, 23.h i d e s , reduction of, 143.Axnines, aliphatic, retinene compounds,with, 263.Amine-alcohol salts, 39.Amino-acids, 184.aromatic, 191.basic, 190.dicarboxylic, 189.determination of, in proteins, 21 1.heterocyclic, 193.polymers, 226.relation of, to carbohydrates, 185.sulphur-containing, 189.syntheses of, 185.a-Amino-acids, fatty, 187.synthesis of, 152.DL-Amino-acids, resolution of, 186.a-Amino-groups, protective agents for,Amino-hydroxy-acids, 187.Ammonia, liquid, apparatus for reactionssolutions of alkali and alkaline-earthAmmonium chloride, spectrum of, Raman,dihydrogen phosphate, isotope effectstetrametaphosphate, crystal structure195.in, 103.metals in, 3 1.23.for, 12.of, 79.(&)-habasbe, 196.Anemia, macrocytic, treatment of, 23 1.32 321 INDEX OF SUBJECTS.Anaemia, pernicious, anti-factor for, 234.treatment of, 240.Analysis, combustion, 280.fusion, 283.gravimetric, 268.inorganic, organic reagents for, 27 1.organic, 280.radioactivation, 285.spectroscopic, Raman, 276.Androgamones, 247.Anhydrovitamin A, 184.Anhydrovitamin A,, 183.Animal Protein Factor, 235.Anionotropy, three-carbon, 125.Anthracene, reduction of, 143.Anthraquinone, nitration of, 133.Anti-folic acid compounds, 231.Antimony compounds, 105.‘‘ Apoerythein,” 243.Arachidonic acid, structure of, 165.Argon, liquid, surface tension of, 19.radioactive, 1 1.Aricine, 203.Aromoline, 202.Arsenates, crystal structure of, 79.Arsenic hydrides, 105.trihydride.See Arsine.Arsine, radioactive, 11.detection of, 298.Aspartic acid, synthesis of, 189.Aspidosperma quebracho, 206Aspidospermine, 206.Astatine, properties of, 11 1.Astaxanthin, 246, 247.Atomic pile as neutron source, 288.weights, reports on, 89.Autodetector, 302.Autoxidation, 31.Axerophthene, 177.GsoAxerophthene, 177.Aza-anthracenes, electronic structure of,Azanaphthalenes, electronic structure of,Azaphenanthrenes, electronic structure of,Azoxy-compounds, reduction of, 146.Bacilli, tubercle, acids from waxes of,160.Bacteria, amino-acids in, 184.Balances, 268.Barium. metatitanate, ferro-electricBatyl alcohol, 167.Beef muscle, extrinsic factor in, 243.Benzene, spectrum of, ultra-violet, 15.Benzene, bromo-, and chloro-, dielectric15.15.15.domains in, 22.losses of, 21.nitration of, 133.sulphonation in, 137.Beryllium, at.wt. of, 92.Beryllium compounds, 93.Biochemistry, 229.nitro-, ionic reactions in, 30.s-trinitro-, molecular compounds of, 38.Bismuth thiocyanate solutions, ions in,thiosulphate solutions, ions in, 105.Blood, analysis of gases of, 296.Bond properties and structure, 12.Borazole, spectrum of, ultra-violet, 15.Borides, crystal structure of, 68.Borine, constitution and spectra of, 14.Boron, high-purity, 94.Boron compounds, 94.hydrides, 94, 95.105.co-ordination compounds of, 12.crystal structure of, 84.&Brass, structure of, 53.y-Brass, structure of, 52, 53.Brillouin zones, 51.Bromination, 138.Bromine, determination of, in organiccompounds, 284.Bromo cresol-purple , 2 7 3.Bromonium ion, 123.Bromophenol-blue, 273.Bromoph thalein-magenta, 273.Bromothymol-blue, 27 3.Brucine, 206.Buta-1 : 2-diene, thermodynamics of, 9.Butane, meso-2 : 3-dibromo-, and erythro-or threo- 3- bromo-2- hydrox y - , 2-acety lderivative, acetolysis of, 122.But-2-ene, 1 : 3-dichloro-, condensationswith, 153.Butyl alcohol, dielectric loss of, 21.bromide, dielectric loss of, 21.tert.-Butyl benzoate, reaction of, wikhmethanol, 122.n-Butyric acid, uy-diamino-, 184.Cadmium, at.wt. of, 94.Cadmium-antimony alloys, surface ten-Caesium, detection of, in sodium saltp,Calcium, masking agents for, 274.separation of, from magnesium, 270.Calcium ammonia, reduction with, 146.salts, 93.selenide, 108.Carbides, crystal structure of, 68.Carbon, chemistry and isotopes of, 100.detection of, in steel, 290.determination of, 280.radio-isotopes of, 10.Carbon monoxide, determination of, 293.in air, 298.in mine-damp, 302.dioxide, determination of, 293, 299.Carbonyl chloride, preparation of, 101.thermodynamics of, 9.compounds, unsaturated, reductlion of,141.u&unsaturated, reduction of, 147.cyanide, 10 1.selenide, 100.Carborundum, colourless, 23.Carotenoids, 244.biochemistry of, 246.sion of, 19.289INDEX OF SUBJECTS.325Carotenoids, cis-trans-isomerism in, 245.spectra, of, absorption, 14.Catalysis, acid, anionotropy and, 126.magnetochemistry of, 34.Catalysts, poisons for, 35.“ supported,” mixed oxides as, 35.Catalytic activity in relation to crystalstructure, 27.hydrogenation , 1 40.Cells, photo-electric, for Raman spectro-graphy, 279.Cementite, crystal structure of, 68.Cephaelin, 203.Cepholopsin, 261.Cerium, at. wt.of, 96.dimers: 97.Cerium oxysulphide, crystal structure of,sulphides, crystal structure of, 70.Chelerythrine, 201.Chelidonium alkaloids, 20 I.Chimyl alcohol, 167.Chlorination, 138, 139.Chlorine, determination of, 301.photochemical reaction of, with hydro-Choline deficiency, effect of vitamin B,,Chromites, 108.Chromium dioxide, 108.Cinchonamine, 203.j3-cycZoCitra1, reduction of, 147.Civetone, 150.Claisen condensation, 153.Clathrate compounds, crystal structure of,Coal, analysis of, 281.Cobalt complexes, 1 12.compounds, oxygen-carrying, 32.Cobalt (11) ions, oxidation of, by ozone, 112.Coccidiosis in chicks, 258.Colloidal ions, molecules giving, 29.Colour vision, theories of, 259.Complexing agents, 273.Complexones, 2 73.Condensations, 150.Conhydrine, 198,#-Conhyd rine, 1 98.Copper, at. wt.and isotopes of, 90.binding of, by serum albumin, 33.crystals, oxidation of, 27.magnetic susceptibility of, 41.chromite catalysts, 140.chromites, 108.compounds, 91.halides, crystal structure of, 74.selenides, 91.Coronene, electronic structure of, 15.Crocidolite, Bolivian, crystal structure of,Cryolite-alumina baths, ionic processes in,Crystal chemistry, 64.70.gen, 110.on, 240.85.Copper acetylides, 92.78.29.structure analysis, 58.defect, 25.Crystals, diffraction of neutron beams by,22.growth of, 26.spectra of, Raman, 23.temperature effects in, 25.Crystallography, 57.Cubanite, crystal structure of, 71.Cuprous azide, crystal structure of, 83.Cuscohygrine, 196, 198.isocyanates, reactions of, 150.Cyanic acid, sodium salt, crystal structureCyanides, oxidation of, by iodine, 101.Cyanine dyes, spectra of, absorption, 14.Cyclisation by reduction, 148.Cyclotron, 290.Cystine, synthesis of, 189.Daphrzartdra alkaloids, 201.Daphnandrine, 202.Daphnoline, 202.Dark-adaptation, pigment formationduring, 259.Decaborane, crystal structure of, 58, 84.cis-Decalin, steric hindrance in, 14.3-DehydroioneneY 178.Dehydro-j3-ionone, 178.Demethylaxerophthene, 177.Demethylisoaxerophthene, 177.Deoxyribosides, activity of, 238.Desulphonation, aromatic, 137.Deuterium halides, solid transitions of, 12.iodide, thermal decomposition of, 1 1.Diacetyl, aldol condensations of, 150.Diamagnetism of mixed liquids, 39.Diamonds, synthetic, 100.Diaspore, crystal structure of, 73.Diatoms, carotenoids in, 246.Diazocyanides, magnetic susceptibility andDi-2-benzthiazolyl disulphide, magneticDibenzyl, crystal structure of, 63.Diborane, crystal structure of, 84.Diboron tetrahalides, 95.Dichroa febrifwga, 210.Diisocyanates.reactions of, 150.Dicyanodiamidine for vanadium precipit-Dielectrics, liquid and solid, physicalDietary factors, extrinsic and intrinsic,Di- (9 -ethoxy - 10 -phenanthryl) peroxide,1 - Diethylaminomethyl - 2 - methoxy -naph-NN-Diethylbenzamide, reduction of, 144.Diethylberyllium, preparation and pro-Diethylthiocyanatogold, 92.Diffusion in gas analysis, 303.thermal, 8.Dihexadec ylhep t adec ylcarbino 1, 1 5 8.Diketen, 149.Diketones, aldol condensation of, 150.of, 23.structure of, 38.properties of, 38,ation, 271.chemistry of, 21.243.magnetic properties of, 38.thalene, 152.perties of, 93326 INDEX OF SUBJECTS.Dimethyl disulphide, configuration of, 17.Dimethylcadmium, 100.Dimethylglyoxime as analytical reagent,272.Dimethylmercury, 100.photolysis of, 32.2 : 6-Dimethylocta-2 : 6-diene, photo-oxidation of, 31.Dimethylzinc, 100.4 : 4'- Di- 1"-naphthylazostilbene - 2 : 2'- di-sulphonic acid, 4 : 4'-di-2"-amino-,disodium salt, 273.'' Diopterin," 232.Diphenyl-p-tolylmethyl, disproportion-ation of, 39.2 : 2'-Dipyridyl, as complsxing agent foriron, 273.2 : 2'-Dippidyls as indicators, 272.Distillation, fractional, 162.in gas analysis, 302.Docosa-11 : 14-dienoic acid, 166.Docosane-1 : 22-diol, 158.Dominator curves, 259, 260.Dysprosium, determination of, 288.Earths, rare, magneto-chemistry of, 40.Echinochrome, 247.Eicosa-11 : 14-dienoic acid, 166.Electric light bulbs, analysis of gas from,Electrocapillarity, 29.Electrochemistry, 2 9.Electrodes, ionic processes at, 31.Electrolytes, molten, 29.Electrolytic conductivity in gas analysis,299.Electrostatic generator, 290.Emetine, 197.Engines, internal combustion, anaIysis ofEpidote, crystal structure of, 77.Epoxides, reduction of, 144.Equilibrium in terms of thermodynamicEriochromeschwarz T, 275.Erythrogenic acid, 166.Esters, carboxylic, alkaline hydrolysis of,297.structure of, 202.gases from, 299.functions, 9.119.replacement reactions of, 119.catalytic hydrogenation of, 140.reduction of, 142.Esterification, 155.Ethane, hezafluoro-, thermodynamics of,Ethyl chloride, dielectric loss of, 21.1 5-Ethylaxerophthene, 177.Ethylene, cis-trans-isomerisation in, 14.Ethylenediaminetetra-acetic acid, 274.1 -Ethynyl-3-methylallyl acetate, acidEudidymite, crystal structure of, 77.Eukryptite, crystal structure of, 76.Europium, determination of, 288.Evodia xanthyloides, 210.9.thermodynamics of, 9.hydrolysis of, 12 1.Evoxanthine, 210.Exaltone, 150.Febrifugine, 2 10.isoFebrifugine, 210.Fermi surface, 51.Ferric thiocyanate, 112.Ferrins as indicators, 272." Ferro-electric " solids, 21.Ferroins as indicators, 272.Fish-liver oils, determination in, ofFlavoxanthin, 244.Fluorine, determination of, 293, 301.in organic compounds, 283.production of, 109." Fly's Eye," 59.Folic acid, 229.assay of, 233.relation of, to vitamin B,, in psrniciousvitamin A, 25 1.kitols from, 180.anzmia, 241.Formic acid, copper salts, 91.Fourier synthesiser, 60.Frogs, carotenoids in, 248.Fucoxanthin, chlorophyll-protein com-a-Furil dioxime for palladium precipitation,Gadolinium, magnetic susceptibility of,96.Gadolinium chloride, nitrosyl chloridecompound of, 104.Gallium, detection of, 290.determination of, in meteorites, 289.Galloxanthin, 245.Gas analysis, 291.plex of, 246.271.apparatus, 29 1.acoustical, 303.microchemical, 294.spectroscopic, 301.by electrolytic conductance afterabsorption, 299.by heat of reaction, 299.by ionisation potential, 300.by magnetic susceptibility, 300.by mass spectrometry, 298.by polarography, 300.by thermal conductivity, 298.inter ferometric , 303.microchemical, 294.spectroscopic, 300, 301.infra-red, 301.Gases, adsorption of, on solids, 28.density determination of, apparatus for,respiratory, micro-analysis of, 294, 295.thermodynamics of, 7.303.Gastric juice, intrinsic factor in, 243.Gelsemiurn sempervirens, 205.Glass, analysis of micro-bubbles of gas in,Glutamic acid, synthesis of, 189.Glutamine, synthesis of, 189.Glycerides, 167.295INDEX OF SUBJECTS.327Glyceryl ethers, 167.Glyoxal, aldol condensations of, 150.Gold-cadmium alloys, catalytic activityand hardness of, 28.compounds, 92.Groutite, crystal structure of, 73.Gynogamones, 247.HEmatopoietic factors, 229.Hafnium, determination of, in presence ofHafnium borohydride, 102.Halides, crystal structure of, 74.Halogens, determination of, in organicremoval of, in combustion analysis, 282.substituent effects of, 124.Halogen compounds, reduction of, 145.fluorides, 109.Halogenation, aromatic, 137.o-Halogeno-acids, fatty, preparation of,Heliotridine, 148.Helium isotopes, 89.liquid, thermodynamics of, 8.Hentriacontanoic acid, 159.Fpaxanthin, 183.Heptoxime,” 272.Herculin, 166.n-Hexadecane, urea complex with, 156.Hexadecanols, 158.Hexamethyldialuminiu, constitution andspectra of, 14.Hexamethylenetetramine, crystal struc-ture of, 23.cycZoHexane, trans- 1 : 2-dibromo-, aceto-lysis of, 122.2 - acetylderivative, acetolysis of, 122.cycZoHexanes, crystal structure of, 58.cycEoHexane-1 : 2-dione, reduction of, 141.cycZoHexanetetra-acetic acid, 1 : 2-di-Hexapentacontanoic acid, 159.cycZoHexene, photo-oxidation of, 31.4-cycZoHex- 1 ’-enylbut- 3 - p - 2-01,Hietidine, synthesis of, 194.Hollandite, crystal structure of, 73.Hormones, fertilization, 247,Hydrazinium dichloride, crystal structureHydrocarbons, alicyclic, surface tensionaliphatic, 156.aromatic, mixed, analysis of, by Ramanspectra, 280.mixed, analysis of, by Raman spectra,278, 279.oxidation of, 32.physical constants of, 17.determination of, in metals and com-zirconium, 289.compounds, 283.155.trans - l-bromo - 2 - hydroxy-,amino-, 274.reduc-tion of, 179.of, 83.of, 19.Hydrogen, active, determination of, 285.pounds, 304.in organic compounds, 280.Hydrogen, ortho-para conversion of, 34.photochemical reaction of, with chlorine,Hydrogen chloride, dissociation of, inliquid, anhydrous, as solvent, 101.110.organic solvents, 3 1.cyanide, determination of, 297.ionic reactions in, 30.deuteride, pure, 90.halides, bond lengths in, 18.peroxide, properties of, 106.sulphide, determination of, 297.Hydrogenation, 140.Hydroxyl groups, determination of, 285.Hydroxylarnmonium bromide andchloride, crystal structure of, 83.Hypobromous acid as brominating agent,110.Hypoxanthine deoxyriboside, 239.Iminodiacetic acid, 273.Indicators, 272.Indicator yellow, 261.Indium chloride, nitrosyl chloride com-Inorganic compounds, magnetic suscepti-Insects, carotenoids in, 248.Insecticidal principles, 166.Insulin, 21 1.Jnterferometer, Zeiss, 303.Interferometry in gas analysis, 303.“ Interstitial ” compounds, 67.Intestines, conversion of provitamin intoIodic acid, crystal structure of, 80.Iodine, co-ordination compounds of, 13.oxidation by, of cyanides, 10 1.oxidation of, by silver sulphate, 92.solutions, 110.pound of, 104.bility of, 39.ethylenediamine compounds, 96.enzymic hydrolysis of, 223.vitamin A in, 255.Kodine pentafluoride, reaction of, withcarbon tetraiodide and tetraiodo-ethylene, 110.[odopsin, 259, 266.Conic chemistry, 29.$Ionone, C,, ketone from, 171.5-Ionylideneacetaldehyde in vitamin ACridium, determination of, 288.Cron, at.wt. and isotopes of, 111.crystals, oxidation of, 27.detection of, 290.L- and y-Iron, self-diffusion in, 11.[ron hydroxides and oxides, 11 1.silicide, crystal structure of, 68.[sanic acid, 166.[satin derivatives as organic reagents, 271.[sotopes, 9.Kalsilite, crystal structure of, 77.Keratin, dielectric constant of, 33.synthesis, 169.wool, combination of, with Orange-I1acid, 33.structure of, 220328 INDEX OF SUBJECTS.Ketens, chemistry of, 148.4-Keto-1 : 1-dimethylpiperidinium iodide,,S-Keto-esters, ketonic fission of, 154.Ketone, C,,, 171.Ketones, aliphatic, synthesis of, 158.syntheses with, 152.aromatic, catalytic hydrogenation of,photochemistry of, 3 1.reduction of, 141.8-Ketosparteine, 196.Ketoyobyrin, 203.Kitol, 180, 252.Kitol,, 180.Krill, carotenoids in, 248.Krypton, isotopes, 90.j?-Lactoglobulin, amino-acids in, 214.140.denaturation of, 225.determination in, of reactive groups, 218.enzymic digestion of, 221.hydrolysates, partition chromatographyof, 216.preparation and composition of, 214.structure of, 221.physical evidence for, 224.Lactones, reduction of, 143.8-Lactones, formation of, 149.6-Lactones, &unsaturated, preparationLanthanons, 88, 96.Lanthanon sulphides, crystal structure of,Lanthanum, at.wt. of, 96.purification of, 97.separation of, from actinium, 98.Lead acetobromides and acetoiodides, 102.bromide, diamagnetism of, 40.compounds, magnetic susceptibility of,of, 149.70.39.Leucsemia, treatment of, 231.Lewam glauca, 198.Leucaenol, 198.Leucine, copolymer of phenylalanine with,225.L-Leucyl-D- and -L-al&e, 195.Linoleic acid, ethyl ester, photo-oxidationsynthesis of, 165.Linolelaidic acid, synthesis of, 165.Linolenic acid, 165.Liquids, macromolecular, 20.mixed, diamagnetism of, 39.structure and yoperties of, 19." supercritical state of, 9.surface chemistry of, 29.Lithium, detection of, 290.Lithium aluminium h ydride, reductionpreparation of, 187.of, 31.with, 140.amide, condensations with, 153.borohydride, reduction with, 146.deuteride, zero point energy of, 23hydride, zero point energy of, 23.Liver, conversion into vitamin A in, 255,extracts, vitamin B,, activity of, 238.Lobsters, carotenoids in, 248.Locusts, carotenoids in, 248.Lupinus macounii, 200.Lysine, synthesis of, 190.Macro-molecules, physical chemistry of,Magnesium, masking agents for, 274.separation of, from calcium, 270.Magnesium carbonate and hydroxide,dissociation equilibria of, 93.Magnetic susceptibility and structure oforganic compounds, 38.in gas analysis, 300.of inorganic compounds, 39.Magnetochemistry, 34.Malonic acid, amino-, acetyl derivative,diethyl ester, use of, in syntheses, 185.Man, adult, vitamin A requirements of,253.Manganese, determination of, in aluminiumManganese oxide catalysts, Weiss constantMannich reaction, 151.Margaric acid, 160.Melicope fareana, 210.Melicopicine, 210.Melicopidine, 210.Melicopine, 210.Mercaptobenzthiazole for rhodium pre-Mercury, liquid, surface tension of, 19.Mercury halides and oxides, 94.Metal atoms, bond radii and co-ordinationMetals, analysis of gases evolved from, 304.calculation of physical properties of, 43.dissolving, reduction by, 146." full " and " open," 44.liquid, surface tension of, 19.theories of, 42.electron-band, 43.free-electron gas, 42.Metallic orbitals, 54.Meteloidine, 196,Methane, radioactivity of, 10.Methanol, fluorination of, 110.Methionine, metabolism of, vitamin B,, in,Methyl cyanide and isocyanide, micro-Methylallyl chlorides, alcoholysis of, 130.N-Methyldiphenylamine-red, 273.2 -Me th ylgl yoxaline, fromfructose or sucrose, 194.1-Methylcycbhexene, photo-oxidation of,31.N-Methylmorphinan, 200.2-Methylquinoline-5-carboxylic acid, 7-amino-, 7-acetyl derivative, 273.2-Methyltetradecanol, 158.Mica, paramagnetism of, 41.Mimosa pudica, 198.32.alloys, 289.for, 35.oxides, crystal structure of, 73.cipitation, 271.number of, 49.239.synthesis of, 189.wave spectra of, 14.2 -hydrox y - INDEX OF SUBJECTS.329Mimosine, 198.Modulator curves, 260.Molybdates, crystal structure of, 79.Molybdenite, magnetic anisotropy of, 41.Molybdenum, separation of, from tech-Molybdenum oxides, 109,Molybdotellurates, crystal structure of, 80.Morphine, 200.Motor spirit, analysis of, by Raman spectra,278.(&)-Muscone, 150.Myosin, 21 1.a-Nphthdavone as indicator, 273.Naphthalene derivatives, reduction of,B-Naphthol, reduction of, 147.Naphthylamines, nitro-, basic strengths of,Neodymium, at. wt. of, 96.Nepheline, crystal structure of, 76.Neptunium compounds, 100.ions, hydrolysis of, 98.radii for, 23.Neutrons, laboratory sources of, 287.“ Niccolox,” 272.Nickel, catalytic, Raney, 140.Nickel complexes, 11 2.netium, 111.crystal structure of, 72.147.16.determination of, organic reagents for,cyanide, ammonia compound, crystaldiformyldiethylenedi - imine - camphor,hydroxide, 112.monoxide, temperature effects on, 26.Niobium pemkzbromide and pentachloride,vapour pressures of, 105.Nioxime as reitgent for nickel, 272.for palladium precipitation, 27 1,Nitration, aromatic, 131.Nitric acid, crystal structure of, 80.solutions, ions in, 103, 104.structure of, in organic solvents, 30.272.structure of, 85.magnetic properties of, 40.in sulphuric acid, properties of, 132.Nitriles, reduction of, 144.Nitrilotriacetic acid, 274.Nitro-compounds, aliphatic, combustionreduction of, 146.Nitrogen, at.wt. of, 103.determination of, in organic compounds,Nitrogen compounds, crystal structure of,of, 281.282.82.fluoride and oxides, 103.oxides, determination of, 297.removal of, in combustion analysis,281.Nitronium ion, 131.perchlorate, crystal structure of, 83.salts, 133.Nitrosyl chloride, vapour pressure of, andits reactions, 104.Nonacosan-1-01, 158.Norvitamin A, 176.“ Octamethylspiro [5: 51 pentasibxane ”,cycloOc tate trmne, diamagnetic suscep t i -resonance stability of, 17.Olefins, 157.autoxidation of, 32.Oleic acid, synthesis of, 164.Organic chemistry, theoretical, 114.compounds, magnetic susceptibility andstructure of, 38.Ornithine, synthesis of, 190.Orthoclase, sanidinised, crystal structureof, 77.Overvoltage, 31.Oxalyl chloride as reagent for preparationof acid chlorides, 166.Oxides, crystal structure of, 72.mixed, catalytic activity and magnetismof, 35.solid, electrical conductivity of, 25.crystal structure of, 78, 79.bility of, 38.Oximes, reduction of, 146.Oxindoles, reduction of, 144.Oxy-acids, crystal structure of, 80.Oxygen adsorbed on charcoal, magneticproperties of, 37.detection of, 290.determination of, 300.in organic compounds, 284.(-)-Oxysparteine, reduction of, 143.Oxysulphides, crystal structure of, 70.Palladium, determination of, in meteorites,289.precipitation of, organic reagents for, 271.Paraffins, 156.Pauling hypothesis, 44.koPelletiorine, 196.Pellitorin, 166.Penicillin, crystal structure of, 58.neopentyl halides, reaotivity of, 117.Peptides, isolation and characterisationof, 219.Periodates, magneto-chemistry of, 40.Per-rhenates, 11 1.Perylene, dipole moments of, 16.Phenanthrene, reduction of, 143.Phenanthridine, reduction of, 143.Phenanthrolines as indicators, 272.1 : 10-Phenanthroline for palladium pre-Phenols, p-nitro-, synthesis of, 151.Phenylalanine, copolymer of leucine with,synthesis of, and its derivatives, 191.1 -Phenylallyl p-nitrobenzoate, rearrange-5-Phenylisogranatanine, 148.( - )-Phenylmethylcarbinyl chloride, reduc-Phenylthiocarbonyl chloride as prdtectivesynthesis of, 195.cipitation, 271.225.ment of, 126, 128.tion of, 145.agent for a-amino-groups, 195330 INDEX OF SUBJECTS.Phosphates, condensed, 105.crystal structure of, 79.Phosphorus, detection of, 290.preparation of, 104.Phosphorus sulphides, 104.Photo-electric recording of Raman spectra,Photography of Raman spectra, 278.Photopic dominator curve, 260.Photo-reactions, 31.Phthalic anhydride as protective agent forPhthalocyanine, mol.wt. of, 16.Phthiocerane, 157.Phthioic acid, 161.Phytic acid for scandium and thalliumprecipitation, 271.Phytofluene, 244.Phytofluenol, 244.Phytomonic acid, 162.Phytomonas tumefaciens, 162.Pigments, retinal, 259, 265.Pimelic acid, ad-diamino-, 184.Platinum, co-ordination compounds of,Plutonium ions, hydrolysis of, 98.isolation of, and its compounds, 100.Plutonium momsulphide, structure of, 65.Poisons, catalytic, 35.Polarography in gas analysis, 300.Polyisobutene polymers, ultrasonic fre-quencies in, 20.Poly dimethylsiloxanes, ultrasonicmeasurements with, 20.Polyglutamic acid, 226.Polyindene, polymerisation of, 41.Polylysine, 225.Polypeptides, synthetic, 2 2 5.Porphyropsin, 259.Potassium, detection of, in sodium salts,Potassium chloros tannates, magneto -dzXtydrogen arsenate, isotope effects for,dihydrogen phosphate, ferro-electrichydroxide, crystal structure of, 23.diiodate as ammonia receiver in Kjel-dinitrososulphite, crystal structure of,selenopentathionate, 108.stannates, 102.telluropentathionate, 108.Potential, redox, modifkation of, by com-Praseodymium, at.wt. of, 96.Praseodymium trifluoride complex, 97.Prawns, carotenoids in, 248.Precipitation for filtration, 270.Prim reaction, 151.Pristme, 157.Prolinb, synthesis of, 193.Promethium, 96.279.~-amino-gr~ups, 195.113.radii for, 23.289.chemistry of, 40.12.domains in, 22.dahl method, 283.83.plexones, 275.Proteins, analysis of, for amino-acids, 213.determinationin, ofreactivegroups, 217.corpuscular and fibrous, 21 1.mol.wt. of, 217.theories of structure of, 212.water absorption by, 33.Protoactinium, coprecipitation experi-ments with, 98.Provitamins, conversion of, into vitaminA, 255.Provitamins A, 245.Pteroic acid derivatives, 230.P t er o ylglu tamic acid, 2 30.Pteroylglutamic acid, 4-amino-, in leuc-Pteroylglutamic acids, metabolism of, 232.Pteroylheptaglutamic mid, 230.Pteroyltriglutamic acid, 230.Purple, visual, 259, 260.Pyrene, electronic structure of, 15.Pyridine, dipole moments and electronicstructure of, 15.Pyrimidine, 2 : 6-dichloro-4-amino-, cry-stal structure of, 64.Pyrolysis curves, 269.Quartz, large crystals of, 9.Quinamine, 203.QuinoI, crystal structure of, 85,Quinoline, 8-hydroxy-, tautomeric forms,Quinolizidines, 148.Quinones, oxidation-reduction potentialsRadioac tivation analysis, 2 85.Radium-beryllium source of neutrons, 287.'' Rain-making," 28.Raman effect, analysis by means of, 276.Ramsdellite, crystal structure of, 73.Rauwolfia serpentinnt, 210.Reactions, addition, 148.Reagents, organic, for inorganic analysis,Reduction, 140.Repandrine, 201.Reproduction, carotenoids in, 247.Resonance absorption, micro-wave para-Retina, pigments of, 259.Retinene,, 181, 261.Retinene,, 181, 261.Rhenium oxyfluorides, I1 1.Rhodium, precipitation of, organic re-agents for, 271.Rhodopsin, 259, 260.RhodospiTillum mbrum, pigment from, 247.Rhodotorula rubra, carotenoids of, 244.Rhodoviolascin, 247.Rhombinine, 200.Rochelle salt, ferro-electric domains in, 21.Rubber, structure and thermodynamics of,Rubidium hydroxide, crystal structure of,Rubremetinium salts, 202.aemia, 231.38.of, 15.271.magnetic, 40.33.23INDEX OF SUBJECTS.331Rutmarpine, 196.Ruthenium, radioactive, fire assay of, 270.Salts, acid, crystal structure of, 80.Samarium and its compounds, 97.magnetic susceptibility of, 96.Sarcoma, ROW, inhibition of, by anti-folic acid compounds, 231.Scandium, precipitation of, with phyticacid, 271.Scotopic dominator curve, 259.Selachyl alcohol, 167.Selenides, 108.crystal structure of, 71.Selenious mid, crystal structure of, 80.Selenium, liquid, density of, 21.molten, surface tension of, 19.Selenochromi tes, 10 8.Selenopentathionates, 108.Self-diffusion with isotopes, 11.Sempervirine, 205.Serine, preparation of, 187.Silicate melts, electrical conductivity of,Silicates, crystal structure of, 76.Silicides, crystal structure of, 68.Silicon, non-cubic, 23.Silicones, crystal structure of, 76.spectra of, infra-red, 33.Silver acetylides, 92.sulphate, iodine oxidation by, 92.Sodamide, condensations with, 153.Sodio triphenylmethane, condensationsSodium, detection of, 290.in liquid ammonia, reduction with, 146.2*isotope, diffusion of, into glass, 10.Sodium borohydride, crystal structure of,hydrogen carbonate, crystal structurenitrate and nitrite, analysis of mixturesof, 279.nitride, Debye temperature of, 23.oxides, 90.polyselenides, 108.selenopentathionate, 108.stannates, 102.telluropentathionate, 108.at.wt. of, 96.29.with, 153.84.reduction with, 146.of, 80.Solid state, physical chemistry of, 22.Solids, adsorption of gases on, 28.Solochrome-blue, 283.Sparteine, 199.(& f-Spartejne, 148.Spectra, configurational and vibrational,17.Raman, 276.Raman and ultra-violet absorption, 14.rotational, 13.with camera, 278.excitation of, 277.of crystals, 23.Spectrographs, microwave, 302.Spectrometry, mass, in gas analysis, 298.Spectroscopy, absorption, analytical appa-Spirilloxanthin, 247.Sprue, tropical, treatment of, 231.Squids, eyes, pigment from, 261.Stannates, 102.Stearic acid, pure, 160.Stibine, detection of, 298.Strontium azide, crystal structure of, 83.selenide, 108.Strychnine, 206.crystal structure of, 58.reduction of, 143.neostrychnine, 208.Strychnone, properties of, 207.Strychnos alkaloids, 206.Styrene, &nitro-, reduction of, 142.Substitution, aliphatic, influence ofneighbouring polar groups on, 122.ratus for, 301.in gas analysis, 300, 301.electrophilic, 13 1.nuclsophilic, 115,Subvitamin A, 183.Sulphamide, preparation of, 108.Sulphides, crystal structure of, 69.diSulphides, reduction of, 146.Sulphonation, aromatio, 135.Sulphosalicyliz acid as masking agent, 273.Sulphur, diatomic, magnetic susceptibilitydetection of, 290.determination of, in organic compounds,isotopes, 106.radio-isotope, in benzylpenicillin, 10.removal of, in combustion analysis, 282.monofluoride, 108.dioxide, determination of, 300.trioxids, determination of, mixed withdioxide, 300.oxides, determination of, 297.Sulphuric acid, nitration in, 132.sulphonation in, 135.Surface chemistry, 28.Surface tension of liquid metals, 19.Systems, non-aqueous, ionic processes in,Tantalum borides, crystal structure of, 68,pen-tabromide and pentachloride, vapouriodide, vapour pressure of, 105.Technetium, crystal structure of, 67.separation of, from molybdenum, 11 1,Telluric acid, electrochemistry of, 108.Tellurides, crystal structure of, 71.Tellurium, reactions of, 108.Tellurium tetraiodide, 108.Telluropentathionates, 108.Teloidine, 196.Tetrachloroaurates, decomposition of, 92.Tetrahydro-4-pyranY 4-hydroxy-, 4-acetylderivative, 151.Tetrahydroyobyrin, 203.of, 107.284.Sulphur compounds, 107.30.69.pressures of, 105332 INDEX OF SUBJECTS.Tetralin, autoxidation of, 32.Tetratriacontanoic acid, 159,Thallium, precipitation of, with phyticacid, 272.isoThebaine, 201.Thermodynamics, 7.Thermopsis rhornbifolia, 200.Thiacyclohexan-4-one methiodide, syn-Thienoyltrifluoroacetone, zirconium com-Thiochromites, 108.Thioglycollic acid as masking agent, 273.Thiophthen, crystal structure of, 64.2-Thiothiazolid-5-one, use of, in syntheses,Thiouracil, effect of, on carotene absorp-Thiourea complexes, 156.Thorium, determination and separation of,ion radii for.23.Thorium iodides, 98.sulphides, crystal structure of, 70.Threonine, synthesis of, 188.Thulium, determination of, in erbium, 289.magnetic susceptibility of, 96.Thymidine, replacement of vitamin B,,Thymine, folic acid replacement by, 233.Thyroid, activity of, and vitamin A, 256.Thyroxine, analogues, synthesis of, 193.DL-Thyroxine, synthesis of, 192.Titanium amides and borohydride, 102.theses with, 152.plex of, 102.186.tion, 257.on vitamin A storage, 256.270.by, 238, 239.sesquioxide, temperature effects on, 26.oxides, crystal structure of, 73.selenida, crystal structure of, 71.tellurides, crystal structure of, 7 1.Tobacco mosaic vim, 21 1.Toluene, p-nitro-, sulphonation of, 135.Toluene-p-sulphonates, hydrolysis of, 145.Tomato bushy-stunt virus, X-ray struc-Torulene, 244.Tourmaline, crystal structure of, 59, 77.Transient orange, 261,264.Trilobamine, 202.Trilon A and B, 274.Tr ime thylaluminium, 100.BBB-Trimethylborazole, 16.Triphenylcarbinol, tri-p-nitro-, nitrationTriphenylmethyl bromide, ionisation of,chloride, reaction of, with methanol inture of, 33.of, 133.with stannic bromide, 30.benzene, 116.Tritium, half life of, 10.Trona, crystal structure of, 82, 101.Trout, brown, carotenoids of, 247.rainbow, carotenoids in, 247.Tryptophan, synthesis of, 193.DL-Tryptophan, resolution of, 194.Tuberculostearic acid, 160.Tungsten, and its compounds, 109.Tungsten oxides, crystal structure of, 72.Tyrosine, synthesis and resolution of,192.Ultrasonics and liquid structure, 20.Undecanoyl chloride, ll-hydroxy-, 1 I-acetyl derivative, reaction of, withoctadecylzinc bromide, 158.Undec-6-enoic acid, 165.Uramildiacetic acid, 274.cisr- and trans-Uranic elements, 88.Uranides, 88.Uranium ions, hydrolyeis of, 98.radii for, 23.precipitation of, organic reagents for,Uranium chlorides, crystal structure of,271.65.trideuteride, 24.tr.ihydride, 24.oxides, crystal structure of, 74.silicides, crystal structure of, 68.Uranium metals, halides, crystal structureUrea, aliphatic complexes with, 156.magnetic susceptibility and structurecrystal structure of, 67.of, 75.of, 38.Vaccenic acid, 165.Valine, preparation of, 187.Vallesia glabra, 206.Vallesine, 206.Vanadium, precipitation of, organicVanadium tetrachloride, dimerisation of,trioxide, as hydrogenation catalyst, 105.reagent for, 271.105.crystal structure of, 72.Vinyl chloride, polymerisation of, 42.Violaxanthin, 244.Vision, biochemistry of, 258.Vitamin A acid, 172.activity, 249.aldehydes, 172, 181.analogues, syntheses of, 175.and its derivatives, spectra of, 262.and its esters and ethers, 168.and thyroid activity, 256.congeners of, 180.determination of, 251, 252.epoxide, 183.mobilisation of liver reserves of, 257.physiology of, 257.requirements of, for adult humans, 253.standards for, 250.standardisation of, 250.biological, 251.synthesis of, 169.isoVitamin A, 176.IzeoVitamin A, 168, 252.neovitamin A,, 252.Vitamin A,, 180, 262.Vitamin A,, 173.Vitamin B12, 234.in animal nutrition, 235.in metabolism, 239Vitamin BIz0 in treatment of perniciousanemia, 240.Vitamin BI2), 235.in treatment of pernicious anzmia, 240.Vitamin B13, 237.Vomicine, 209.Vomipyrine, 210.Water, absorption of, by proteins, 33.dissolved, effect of, on crystal structure,vapour, determination of, 299, 300.27.Weighing, 269.Weights, 269.Wells, thermo-artesian, 8.Whale-liver oil, determination in, ofvitamin A, 252.Xenon, isotopes, 90.Xerophthalmia, effect of earotene in, 256.Yobyrin, 203.Yohimbine, 203.Yohimbine alkaloids, theory of formationof, 197.Yttrium, magnetic susceptibility of, 96.Zinc, at.wt. of, 94.Zinc oxide, solubilities of, in metallicoxides, 24.Zirconium, determination of, in presenceof hafnium, 289.Zirconium compounds, 102.oxysulphide, crystal structure of, 71.Zoopherin, 236PRINTED LV GREAT BRITAIN BYRICHARD CLAY AND COMPANP, LTD.,RUNGAP, SUFFOLG

ISSN:0365-6217    

DOI:10.1039/AR9494600323

出版商:RSC    

年代:1949

数据来源: RSC