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Telegraphic Address:" Gasthermo, Isling,London."Telephone :Clerkenwell 2030.The mark of precision and eficiency.-BRITISH MADETHROUGHOUTIf you use heat-it pays to measure it accuratelyB. BLACK & SON1, Green Terrace, Rosebery Avenue,LONDON, E.C.1Thermometer Manufacturers(MERCURY IN GLASS TYPE)Original Makers of the Improved, Gas-filled, Permanent Thermometers forLaboratory and Industrial Processes.Standard Thermometers of the highestaccuracy covering over a range fromminus 200 to plus 52oOC.The black filling-in etchings will resistall solvents with the exception of thosethat attack the glass itself.The National Physical LaboratoryCertificates supplied, with any type.Of all the principal Scient$c Instrument and LaboratorgApparatus Manufacturers.1THE POLYTECHNIC, REGENT ST., W .lDEPARTMENT OF CHEMISTRYHead of Department : H. LAMBOURNE, M.A., M.Sc., F.I.C.Day Courses:H.Sc. Degree SpeciaI and General (External), London University.Xssociateship of the Institute of Chemistry (A,I.C.) 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ISSN:0365-6217    

DOI:10.1039/AR93431FP001

出版商:RSC    

年代:1934

数据来源: RSC

摘要:

TABLE OF ABBREVIATIONS EMPLOYED IN THE REFERENCES. xiERRATA.VOL. 30, 1933.Page Line188 14 for “ isoamylamine ” read “ isoamylaniline.”1 9 4* for “ (XXVIII) ” read “ p-aminoisoamylbenzene.”* From bottom

ISSN:0365-6217    

DOI:10.1039/AR9343100011

出版商:RSC    

年代:1934

数据来源: RSC

摘要:

ANNUAL REPORTSO N THEPROGRESS OF CHEMISTRY.GENERAL AND PHYSICAL CHEMISTRY.1. THE HEAVY ISOTOPE OF HYDROGEN.NO apology is necessary for devoting a whole section to one elementin view of the fundamental theoretical interest of molecules con-taining the new isotope and its great possibilities for use as ailindicator in the physical and chemical behaviour of hydrogen com-pounds. Nearly 200 papers have appeared in this field during 1934,and the present report will be chiefly confined to indicating thedirections in which work is being carried out, without discussingin any detail the theoretical points involved. As regards nomen-clature, the name “deuterium ” seems to be gaining favour inEurope as well as in America, and it will be used in this report.It is adopted in the Journa$l of the Chemical Society.“Heavy water,” or deuterium oxide, is no longer a chemicalcuriosity, but can now be bought in both continents either in thepure state or mixed with various proportions of H20.The electro-lytic method of separation is still the only one used in practice, anda number of accounts of detailed procedure have been published.1The use of nickel cathodes in sodium hydroxide is usual, but alter-native combinations are lead electrodes in sulphuric acid andnickel in sodium sulphate s ~ l u t i o n . ~ The theory of the electro-lytic separation will be dealt with later in this report.The ratio D : H in naturally occurring water is dealt with else-where in these Reports.* The ratio in water from different sources,which is of great interest from the point of view of the productionP. Harteck, Proc.Physical SOC., 1934, 46, 277; A., 236; H. S. Taylor,H. Eyring, and A. A. Frost, J. Chem. Physics, 1933, 1, 823; A,, 1934, 154;L. C. Anderson, J. 0. Halford, and J. R. Bates, ibid., 1934, 2, 342; A., 851;K. Schwarz, L. Kuchler, and H. Steiner, 2. Elektrochem., 1934, 40, 298; A.,S52.* L. Tronstad and J. Bnin, ibid., p. 556; A., 1077; T. Titsni, K. Kurano,and M. Harada, Bull. Chm. SOC. Japan, 1934, g, 269; A., 1077.3 Idem, ibid., p. 272; A., 1077.P. 9814 GENERAL AND PHYSICAL CHEMISTRY.of the heavy isotope and the mechanism of the processes by whichthe water is formed, has been the subject of several researches, allof which rely on density measurements, and in view of the verysmall differences of density involved, it is important to purify thewater very thoroughly, and also to avoid fractionation on distill-ation.on the water derived from benzene, kerosene, and honey.A largenumber of specimens of water of mineral, vegetable, animal, andindustrial origin have been examined by E. W. Washburn and Smith,'and by a team of workers at the Imperial College, using elaborateprecautions.8 The latter authors claim a relative accuracy of 2parts per million in the isotopic ratio. Most of the natural sampleswere found to contain more deuterium than ordinary tap water,which is probably due to evaporation. No significant variationswere found for the same type of water at different points of theearth's surface. I n agreement with other authors, they find that thecrystallisation of salts from water causes no displacement of theisotopic ratio.g On the other hand, fractional freezing was foundto give rise to a small separation, which may account for differencespreviously reported in the densities of natural and artificial ice.There is, however, some dispute as to the facts: while E.S.Gilfillan 10 also finds a separation, G. Bruni l1 obtained negativeresults on repeating his former work with M. Strada.12 Thedisagreement about these experiments carried out with pure watershows the need for caution in accepting results obta,ined with waterfrom biological sources.Observation ofthe atomic spectra of the isotopes of hydrogen provides a verydirect test of the effect of the nuclear mass on the electronic spectra.Such measurements have been carried out by a number of workers,14M.Dole 5 found that this error invalidated his earlier workVery pure D, has been obtained by diff~si0n.l~J . Chem. Physics, 1934, 2, 548; A., 1185.Ibid., p. 337 ; A., 853.Science, 1934, 79, 188. * H. J. EmelBus, F. W. James, A. King, T. G. Pearson, R. H. Purcell,and H. V. A. Briscoe, J., 1934, 1207, 1948; A., 1080.* H. Erlenmeyer and H. GBrtner, Nature, 1934, 134, 327; A,, 1080;J. A. N. Friend, ibid., p. 463; A., 1062.10 J. Amr. Chem. SOC., 1934, 56, 2201; A., 1317.11 Ibid., p. 2013; A., 1185.la Atti R. A d . Lincei, 1934, [vi], 19, 453; A., 1080.l3 H. Harmsen, G. Hertz, and W. Schutze, 2. Physik, 1934, 90, 703; A.,I1 85.l4 D.H. Rank, Physical Rev., 1932, [ii], 42, 446; A., 1933, 1219 ( y line);R. C. Williams and R. C. Gibba, ibid., 1934, [ii], 45,475; A., 675 (fino structureof Ha and Da); J. K. Robertson, Nature, 1934, 184, 378; A., 1147 (Balmerlines); J. S. Foster and A. H. Snell, ibid., p. 568; A., 575 (Stark effect)16; BELL: THE HEAVY ISOTOPE OF HYDROGEN.and the small shifts observed are in complete agreement with thetheory. Effects of much greater magnitude and complexity areobserved in the molecular spectra of hydrogen and its compounds.To a very good approximation we may regard the potential-energycurves as being unchanged,15 and it is then an easy matter to cal-culate (for a diatomic molecule) the effect of replacing H by D onthe energy of the vibrational states, while the rotational statesare affected only by the change in the moment of inertia.Taking into account the fact that a mixture of the two isotopescontains the species H,, D,, and HD, all the features of the vibration-rotation spectrum can be predicted, and the results obtained agree wellwith the predictions.lG I n the c8se of the D, molecule alternationsin the intensity of the rotational spectrum reveal the presence ofortho- and para-modifications, and show that the nuclear spin ofthe deuton is 1, Le., twice that of the proton.1' Similar calculationscan be carried out for other diatomic molecules containingdeuterium, e.g., DC1,18 AlD,19 and OD.20 The interpretation of theisotope effects in the spectra of molecules containing more than twoatoms is more difficult, but it is just in these cases that valuableinformation may be obtained.The replacement of H by Drepresents a change in mass without any change in the forceconstants or other characteristics of the molecule, and may thusbe regarded as a, new independently variable parameter. Inmany molecules the partial replacement reduces the symmetryin such a way as to increase the number of observable frequencies,e.g., in the case of CH, and CH3D.21 A number of other compoundshave been investigated.22The spectroscopic data are sufficiently well established to allowa complete calculation of the equilibrium properties of a gaseousmixture containing given proportions of H and D. The propert'iescalculated include the equilibrium constant for the reaction16 This is not justified for very refined calculations: me e.g., R.L. deIhonig, Physica, 1934, 1, 617; A., 826.16 See, e.g., G. H. Dieke and R. W. Blue, Nature, 1934, 133, 601; A., 575.17 G. M. Murphy and (Miss) H. Johnston, Physical Rev., 1934, [ii], 46, 95;18 J. H. Hardy, E. F. Barker, and D. M. Dennison, ibid., 1932, [ii], 42,1s W. Holst and E. Hulthdn, Nature, 1934, 133, 496; A., 472.20 H. L. Johnston and D. H. Dawson, Naturwiss., 1933,21,495 ; A., 1933,763.21 E. F. Barker and N. Ginsburg, J . Chem. Physics, 1934, 2, 299; A., 716.21 See, e.g., E. Bartholorn6 and K. Clusius, 2. Elektroch,en&., 1934, 40, 529;A., 941; J. W. Ellis and B. W. Sarge, J. Chem. Physics, 1931, 2, 559; A.,1154 (D,O and HDO); A.McKellar and C. A. Bradley, Physical Rev., 1934,46, 664; A., 1288 (C,HD); G. B. B. M. Sutherland, Nature, 1934, 184, 775;A., 1935, 10.A., 1051; G. N. Lewis and (Miss) M. Ashley, ibid., 1933, 43, 857.279; A., 1933, 6.See also next section of this report16 GENERAL AND PHYSICAL CHEMISTRY.H, + D, + 2HD,23 the equilibrium between ortho- and para-H2and ortho- and ~ a r a - D , , ~ ~ the equilibrium between atoms andmolecules,25 and the specific heat.26 The experimental values arein all cases in agreement with the values calculated from thespectroscopic data. Determinations of the specific heat by meansof the hot-wire method may be used to determine the amounts ofH,, D,, and HD present in any sample of hydrogen.,'The same considerations can be applied to other chemical equili-bria involving the hydrogen isotopes ; e.g., it is found, as predicted,28that the degree of thermal dissociation of DI differs from that ofHI by about 6% a t 468°.29 There are two principal ways in whichthe theoretical expression for the equilibrium constant of such areaction involves the mass; first, in the zero-point energy, andsecondly, in the chemical constant.These factors act in oppositedirections, and approximately balance for most pairs of isotopes,but they may give rise to considerable differences in the case of thehydrogen isotopes. For molecules containing more than onehydrogen atom, the partial replacement of H by D will alsochange the symmetry number contained in the chemical con-stant, and thus will affect the equilibrium.This is the case forthe reaction H, + HDO H,O + HD, which is of great practicalimportance. I n this case the interpretation of the spectra in termsof energy states is not quite complete; nevertheless, the experi-mental measurements of this equilibrium are in good accord withthe calculations from spectroscopic data.30 At room temperaturethis reaction has an equilibrium constant of about 3.8, comparedwith the " classical " value of unity. It is possible that equilibriawhich differ greatly for the two isotopes may eventually displacethe electrolytic method as a source of deuterium compound^.^^23 D. Rittenberg, W. Bleakney, and H. C. Urey, J . Chem. Physics, 1934,2, 48; A., 237; A.Farkas and L. Farkas, Proc. Roy. SOC., 1934, [A], 144,467 ; A., 608 ; A. J. Gould, W. Bleakney, and H. S. Taylor, J. Chem. Physics,1934, 2, 367 ; A., 1074.24 A. Farkas, L. Farkas, and P. Harteck, Proc. Roy. SOC., 1934, [A], 144,481; A., 608; H. Motz and F. Patat, Monatsh., 1934, 64, 17; A., 480.25 H. L. Johnston and E. A. Levy, J. Chem. Physics, 1934, 2, 389; A., 951.26 K. Clusius and E. Bartholom6, Naturwiss., 1934, 22, 297; A., 722;27 A. Farkas and L. Farkas, Zoc. cit., ref. (23).28 See Ann. Reports, 1933, 30, 32.2B D. Rittenberg and H. C. Urey, J . Amer. Chem. SOC., 1934, 56, 1885;A., 1172.30 R. H. Crist and G. A. Dalin, J. Chem. Physics, 1934, 2, 442, 735; A.,962 ; L. Farkas and A. Farkas, Trans. Paraday SOC., 1934,30, 1071 ; A., 1935,33; T.Forster, 2. physikal. Chem., 1934,27, [B], 1, 319; A., 1935, 33.2. Elektrochem., 1934, 40, 524; A , , 951.31 See M. Polanyi, Nature, 1935, in the pressBELL: THE HEAVY ISOTOPE OF HYDROGEN. 17A number of other equilibrium properties of deuterium and itscompounds have been measured. Many of these admit of noquantitative interpretation, but it is often possible to make inter-esting qualitative comparisons between the '< heavy " and '< light "compounds. A number of workers have studied the thermalproperties of liquid and solid D2,32 The boiling point is 23-5" K.and the triple point 18.6" K. Comparisons of vapour pressurehave been made for DC1 and HC1 and for DCN and HCN byG. N. Lewis, R. T. Macdonald, and P. W. S c h ~ t z , ~ ~ and for DF andHF by W.H. Claussen and J. H. Hildebrand.34 Only small differ-ences were observed ; this is particularly interesting for HF and DF,since differences due to different degrees of association (as for H20and D20) might have been anticipated. The refractive index,freezing point, density, and viscosity of pure liquid D,O have beenmeasured,35 giving values differing somewhat from those previouslyaccepted.36 The ionic product of D20 has been found to be aboutone-third that of H20 a t the same ionic c~ncentration.~' Thedissociation constants of a few weak electrolytes (containingD in place of H) have been measured in D20, giving resultsconsiderably lower than the corresponding values in H20.38On diluting D20 with H20, heat is absorbed, indicating that thereare stronger intermolecular forces (greater association) in theformer than in the latter.39 DHO diffuses into H,O with an ab-normally great velocity, presumably due to some chain mechanismsuch as that postulated to explain the mobility of the hydrogeni0n.4~To the physical chemist, special interest centres round the differ-ences in reaction velocity between hydrogen compounds and thecorresponding deuterium compounds.As pointed out in lastyear's Report,41 the determining factor in many cases will be the32 K. Clusius and E. Bartholomh, Naturwiss., 1934, 22, 526; A., 1062;G. N. Lewis and W. T. Hanson, J, A m r . Chem. SOC., 1934, 56, 1687; A.,1062; R. B. Scott, F. G. Brickwedde, H. C. Urey, and M. H. Wahl, J . Chem.PhYSk, 1934, 2, 454; A., 1164.33 J .Amer. Chem. SOC., 1934, 56, 494, 1001; A., 355, 590.34 Ibid., p. 1820; A., 1062.3 5 H. S. Taylor and P. W. Selwood, ibid., p. 998; A,, 590.36 Cf. Ann. Reports, 1933, 30, 31.37 B. Topley and W. F. K. Wynne-Jones, Nature, 1934,134, 574; A . , 1173;E. Abel, E. Bratu, and 0. Redlich, 2. physikal. Chem., 1934,170,153; A., 1173.36 G. N. LewisandP. N. Schuta, J. Amer. Chem. SOC., 1934, 56, 1913; A.,1173.39 E. Doehlemann, E. Lange, and H. Voll, Naturwiss., 1934, 22, 526; A .1071.40 W. J. C. Orr and D. W. Thompson, Nature, 1934,134, 776.4 1 Ann. Reports, 1933, 110, 3218 GENERAL AND PHYSICAL CHEMISTRY.difference in zero-point energy in the initial states, which will ingeneral lead to a higher activation energy (and hence a lowerreaction velocity) for the deuterium compounds.It has beennoted by M. Polanyi42 that in some cases (especially for reactionsof free atoms) this state of affairs may be reversed by the differenceof zero-point energies in the activated complex. Another way inwhich the difference of mass may lead to differences in reactionvelocity is in the behaviour of the particles in crossing the potentialbarrier. For heavy atoms this process can be described in termsof classical mechanics, but for H and D the wave nature ofthe particles must be taken into and calculation showsthat at not too high temperatures this effect alone may leadt o considerable differences between the isotopes .44 Finally, smalldifferences may also be caused by the differences in thermalvelocity. It is thus difficult to produce any complete explanationof the experimental data, but in a number of cases the facts seemto be qualitatively explicable in terms of the differences in zero-point energy alone.L. Parkas and A. Farkas 45 find that D, reactswith chlorine one-third as fast as H, in the photochemical chainreaction, and attribute this to the initial reaction D,(H,) + GI---+DCl(HC1) + D(H). H. W. Melville 46 has investigated the reactionof H and D atoms and molecules with oxygen, nitrous oxide,ethylene, acetylene, and carbon monoxide. When the atomsreact in the gas phase, the only differences observed can beattributed to differences in collision frequency, but when moleculestake part, differences attributable to zero-point energies areobserved, and the same is true for the reaction of atoms adsorbedon a surface. None of the data indicated that the “leakage ” ofthe atoms through potential barriers was an appreciable factor.The reaction between deuterium and oxygen has also been investi-gated.47 The change in the upper pressure limit can be accounted forby the different deactivating powers of H, and D,, owing to theirdifferent molecular velocities, the velocities of the actual branchingprocesses being substantially the same.The surface reaction isabout 1.6 times slower for D, than €or H, : after allowing for the4a Nature, 1934, 133, 26; A., 150.43 R. P. Bell, Proc. Roy. SOC., 1933, [A], 139, 466; A., 1933, 231.44 C. E. H.Bawn and G. Ogden, Trans. Paraday Soc., 1934, 30, 432; A.,4s Naturwiss., 1934, 22, 218; A., 603.48 Nature, 1934, 133, 947; A., 847; J., 1934, 797, 1243; A , , 851, 1078.47 C. N. Hinshelwood, A. T. Williamson, and J. H. Wolfenden, Nature,1934,133, 836; A., 736; PTOC. ROY. SOC., 1934, [A], 147, 48; A., 1935, 39;A. A. Frost and H. N. Alyea, J . Arner. Ohern. SOC., 1934, 56, 1251; A., 736;K. Clusius and H. Gut’schmidt, Naturwiss., 1934, 22, 693; A., 1178.602; R. P. Bell, Proc. Roy. SOC., in the pressBELL: THE HEAVY ISOTOPE 03 HYDROGEN. 19different diffusion coefficients, this can be accounted for by thedifferences in the zero-point energies of the two molecules. Therates of diffusion of the two isotopes through palladium can beexplained on the salme basis.48 Other gas reactions which have beenstudied are D, + Br, 49 and C,H, + HD; 50 in the latter casethe two reactions C2H4 + HD +C,H,D + H, and C,H, + HD --+C,H,D take place simultaneously.In the heterogeneous hydro-genation of ethylene the velocity-temperature curves for H, and D,cross; this is probably due t o the greater adsorption of thelatter.,l The kinetics of the reaction H, + D, 2HD arecomplex, and probably involve the separate homogeneous reactions$1, + D HD + D, D, + H + HD + H, and H, + D, +=Z H D . ~ ~A number of reaction velocities have been compared in H,O andD,O. The same general principles will of course apply, but thetheoretical treatment is complicated by the change of medium andthe possibility of interchange between solvent and solute.Most ofthe reactions studied have been of the catalytic type. The muta-rotation of glucose has been studied by E. PBSCU,~~ E. A. Moelwyn-Hughes, R. Klar, and K. F. B~nhoeffer,~~ W. F. K. Wynne-J~nes,~~and V. K. LaMer and W. H. Hami11.56 With H,O' and D,O' ascatalysts, the ratio of the velocities a t room temperature is about1-3 : 1 and the differences in the activation energies 1250 cals.For catalysis by the solvents H,O and D,O the ratio of the velocitiesis about 3-8 : 1 and the difference in the activation energies (aftercorrection for the temperature coefficient of viscosity) 550 cals.The differences in velocity are in each case accounted for by thedifferences in activation energy and viscosity. The inversion ofsucrose catalysed by H,O' and D,O' has also been studied by anumber of authors.57 The somewhat surprising fact emerges thatthe velocity of inversion in D,O is nearly twice as great as in H,O ;4* A.Farkas and L. Farkas, Proc. Roy. SOC., 1934, [A], 144, 467; A., 608.49 H. F. Bonhoaffer, F. Bach, and E. Fa.jans, 2. physikal. Chem., 1934, 168,50 A. Farkas, L. Farkas, and E. K. Rideal, Proc. Roy. SOC., 1934, [ A ] , 146,5 1 R. Klar, 2. physikal. Chern., 1934, 27, [BJ, 319.52 E. K. Rideal, Proc. Roy. SOC., 1934, [ A ] , 144, 481.53 J . Arner. Chem. SOC., 1934, 56, 745; A., 494.54 2. physikal. Chem., 1934, 169, 113; A., 971; ibid., 1934, 26, [B], 272;55 J . Chem. Physics, 1934, 2, 381; A , , 1075.56 Ibid., p. 891.57 E. A. Moelwyn-Hughes and K.F. Bonhoeffer, Natumoiss., 1934,22, 174;p. Gross, H. Suess, and H. Steiner, ibid., 1934, 22, 662; A., 1180; Moelwyn-Hughes, Eoc. cit., ref. (54).313; A., 736.630; A., 1315.A., 107520 GENERAL AND PHYSICAL CHEMISTRY.however, this may be explained by assuming that the sucrose-D'complex is formed to a greater extent than the sucrose-H' complex.It may be noted that the enzymatic inversion of sucrose is somewhatslower in D20 than in H2OS5*Wynne- Jones 55 has measured the rate of neutralisation of nitro-ethane by baryta in H20 and by Ba(OD), in D20. He concludesthat under the same conditions the rate of transfer of protons is atleast 10 times that for deutons, and the rate of transfer of H ' t oOD' in D20 is about 50% greater than its rate of transfer to OH'in H20.The discharge of the two isotopes of hydrogen by metals, with orwithout the application of an electric field, constitutes a specialproblem in reaction kinetics.The preferential discharge ofH in electrolysis is, of course, the basis of the usual method ofseparation, and it is found that the chemical dissolution of metalsin water containing both H and D always leads to preferentialliberation of the former.59The theory of these processes is a t present very uncertain; theo-retical treatments from different points of view have been given,but there is not yet sufficient experimental evidence to discriminatebetween the different possible mechanisms.60 The electrolyticseparation coefficient is not greatly affected by change of electrodemetal or current density, but occasionally acquires abnormallylow values, e.g., with activated platinum electrodes.62 This isprobably due to the partial establishment of the equilibriumHD + H,O =$ H, + HDO, catalysed by the metal; 63 thisfactor makes it difficult to conclude anything about the primaryproducts of the electrolysis, and may account for some of theerratic results which have been obtained.The heavy isotope of hydrogen has already been used in a numberof cases for detecting and measuring the interchange of hydrogenbetween different substances.The theoretical implications of theresults obtained are so varied that we can do no more here than58 E. W. R. Steacie, 2. physikal. Chem., 1934, 27, [B], 1.E. D. Hughes, C.K. Ingold, and C. L. Wilson, J . , 1934, 493; A., 612;A. Farkas and L. Farkas, Nature, 1934, 133, 139; A,, 264; J. Horiuti andA. L. Szabo, ibid., p. 327; A., 375; C. 0. Davis and H. L. Johnston, J . Amer.Chern. SOC., 1934, 56, 492; A., 375.6o M. Polanyi, Naturwiss., 1933, 21, 316; A., 1933, 659; B. Topley andH. Eyring, J. Chem. Physics, 1934, 2, 217; A., 851; R. P. Bell, ibid., p. 164;A., 738; R. H. Fowler, Proc. Roy. SOC., 1934, [A], 144, 452; A., 609; C. E. H.Bawn and G. Ogden, Trans. Paraday SOC., 1934, 30, 432; A , , 602.R. P. Bell and J. H. Wolfenden, Proc. Roy. Soc., 1934, [A], 144, 22.G2 Topley and Eyring, Zoc. cit., ref. (60).G3 A. Farkas and L. Farkas, Proc. Roy. SOC., 1934, [A], 146, 623 ; A., 1316WOODWARD : THE RAiiAN EFFECT.21report the facts. Hydrogen gas does not interchange with watera t ordinary temperatures except in presence of a catalyst,64 incontradiction to the previous observation of M. L. O l i ~ h a n t . ~ ~ Nointerchange takes place between water and potassium acetate,benzoate, or hypophosphite, but ethylene glycol immediatelyexchanges one-third of its hydrogen.66 Between acetone and water,exchange is extremely slow in neutral solution, more rapid in acidsolution, and still more rapid in alkaline solution ; all six hydrogensare e~changed.~' There is also slow interchange with acetaldehyde,formaldehyde, and acetal.68 Acetylene and water exchange inpresence of alkali, but not in pure water or phosphoric acid solution.69Benzene and water interchange in the presence of platinum-black 7Oand of sulphuric a ~ i d .~ 1 It is hardly necessary to point out theimmense possibilities of work of this kind, particularly from the pointof view of the reactivity of hydrogen atoms in organic compoundsand the theory of both homogeneous and heterogeneous catalysis.R. P. B.2. THE RAMAN EFFECT.Several relatively short references to the Raman effect have beenmade in previous Annual Rep0rts.l The objects of the presentReport are (1) to give a rather more connected account of some ofthe applications of the effect t o problems of interest in chemistryand (2) to illustrate these applications by selected examples, withspecial regard t o recent work. So large and varied is the literature(about a thousand papers have already appeared on the subject)that nothing like completeness is claimed on either score.A fullbibliography from July 1930 to August 1932 inclusive has beencompiled by S. C. Sirkar 2 to form a continuation of an earlier64 A. J. Gould and W. Bleakney, J. Amer. Chem. SOC., 1934, 56, 247; A.,264.See Ann. Reports, 1933, 30, 33.66 N. F. Hall, E. Bowden, and T. 0. Jones, J. Amer. Chem. SOC., 1934, 56,6 7 K. Schwarz and H. Steiner, 2. physikal. Chem., 1934, 24, [B], 153;68 R. Klar, Zoc. cit., ref. (67).6s L. H. Reyerson and S. Yuster, J. Amer. Chem. SOC., 1934, 56, 1426;A., 863.70 H. Horiuti, G. Ogden, and M. Polanyi, Trans. B'araday SOC., 1934, 30,663; A., 973.7 1 C. K. Ingold, C. G. Raisin, and C. L. Wilson, Nature, 1934, 134, 734.For a discussion of the mechanism, see idem, also Horiuti and Polanyi, ibid.,p.847.1 Ann. Reports, 1929,26, 16, 127, 286; 1931,28, 182,284,370; 1932,29,23.760; A., 497.A., 613; R. Klar, 2. physikal. Chem., 1934, 26, [B], 335; A., 1080.IndiGcn J . Phystks, 1932, 7, 43122 GENERAL AND PHYSICAL CHEMISTRY.bibli~graphy.~ It is arranged under general subject headings andhas an author index and a substance index.The Raman Eflect in Chemical Analysis.-When monochromaticlight of frequency is scattered by a dust-free transparent substance(solid, liquid, or gas), the scattered spectrum in general contains(in addition to a line of unchanged frequency *) a number ofrelatively feeble new lines4 of modified frequencies v’. Theseso-called Raman lines are characterised by the fact that the magni-tudes of the frequency shifts v0-v’ (Raman frequencies) are in-dependent of v0 and determined only by the nature of the scatteringmolecules.The experimental technique for photographing Ramanspectra remains essentially similar to that described by K. W. P.Kohlrausc h.Each different scattering molecular species gives its own charac-teristic Raman spectrum-writes (as it were) its autograph on thephotographic plate. The most obvious application to chemistry,and one involving no knowledge whatever of the mechanism of theeffect, is for the identification of different molecular species. Theusefulness of the method becomes apparent in view of the factsthat (1) the components of a mixture in general exert practicallyno effect on each other’s Raman spectra and (2) small differencesof molecular-structure may be associated with very marked differencesof spectra.An advantage of the Raman effect over some otherphysical methods (e.g., refractivity, Kerr effect, dipole moment, etc.)is that the spectra consist of lines and therefore remain discrete evenwhen superimposed, so that the components of a mixture preservea readily recognisable individuality. Both theory (see below) andexperiment show, further, that for a given molecular species theintensity of the effect is directly proportional to the number ofscattering molecules, ie., for constant volume is proportional tothe concentration. Hence the Raman effect can be used forquantitative as well as for qualitative analysis.In this connexion,as in all the applications, the scope is limited by the feebleness ofIndian J . Physics, 1931, 5, 257.(Sir) C. V. Raman and K. 8. Krishnan, Nature, 1928,121, 601 ; A., 1928,461; C. V. Raman, Indian J. Physics, 1928, 2, 387; A., 1928, 685; C. V.Raman and K. S. Krishnan, ibid., p. 399; A., 1928, 1075; G. Landsberg andL. Mandelstam, Naturwiss., 1928, 16, 557; A., 1928, 936.‘‘ Der Smekal-Raman-Effekt,” Springer, Berlin, 1931.See, e.g., R. E. Whiting and W. H. Martin, Trans. Roy. Soc. Canada,1931, [iii], 25, 111, 87; A., 1932, 320; A. Dadieu and K. W. F. Kohlrausch,Physikal. Z., 1929, 30, 384; A., 1929, 976; ibid., 1930, 31, 514; A., 1930, 840.* It has recently been shown (W. Ramm, Physikal.Z., 1934, 35, 756;A., 346) that this line has a fine structure, being accompanied by others ofvery slightly modified frequency. These are due to a cause essentially differentfrom that operative in the Raman effect, and will not be considered hereWOODWARD : THE RAMAN EFFECT. 23the effect. However, it has been found possible to detect, e.g., about2 yo of unsaturated impurities in cyclopropane derivatives ; benzene-toluene mixtures can be analysed with an accuracy of about 5% ;and as little as 0.4y0 of styrene has been detected in ethylben~ene.~The Raman effect can be used where ordinary chemical methodsare hardly applicable, e.g., to detect m-xylene (down to 1%) in anop-mixture.1° Amongst other applications may be mentioned thedistinction between cis-tram l1 and other isomerides l2 and thestudy of degree of hydrolysis,13 polymerisation,l* formation ofmixed molecules from phosphorus trichloride and tribromide,15molecular structure of nitrobenzene above and below its transitiontemperature (no evidence of difference being found), l6 complexityof the mercurous ion in solution,17 and velocity of cis-trans-change 18and of esterification.19Special interest attaches to the study of the degree of ionisationof electrolytes in solution by means of the Raman effect.Themethod makes it possible to distinguish between ions and un-ionised molecules and to follow quantitatively the changes in theequilibrium between them as the concentration is altered. Referencehas already been made 2O to this work, which has shown that nitricand sulphuric acids are only partly ionised in water at moderateconcentrations. These results have subsequently been confirmedby more detailed studies of these acids.2l Hydrochloric acid, whichappears to be practically completely ionised in aqueous solutions,mR.Lespieau, M. Bourguel, and R. L. Wakeman, Compt. rend., 1931,193,238; A., 1931, 1147.8 (Miss) E. A. Crigler, J . Amer. Chem. Soc., 1932, 54, 4207; A,, 1933, 7.J. Weiler, Verhandl. deut. physikal. Ges., 1932, 13, 5.10 L. Birkenbach and J. Goubeau, Ber., 1932, 65, [B], 1140; A., 1932, 984.11 0. Miller and L. Piaux, Compt. rend., 1933, 197, 412; A., 1933, 998.l2 M. Milone, Gaxzetta, 1933, 63, 456; A., 1933, 1225; P. Lambert and J.Lecompte, Compt. rend.,.1934, 198, 1316; A., 583.13 P. Krishnamurti, Indian J . Physics, 1931, 6 , 345 ; A., 1932, 228.14 S. Bhagavantam, ibid., 1930, 5, 49; A., 1930, 1235.l5 B. Trumpy, 2. Physik, 1931, 68, 675; A., 1931, 785.16 A. M. Thorne and P. L. Bayler, Physical Rev., 1932, [iil, 41, 376; A.,1933, 1229; H. F. Hertlein, 2. Physik, 1034, 87, 744; A., 346.1' L. A. Woodward, Phil. Mag., 1934, [vii], 18, 823.18 H. Conrad-Billroth, K. W. F. Kohlrausch, and A. Pongratz, 2. phgsikal.19 S . Partharasathy, Phil. Mag., 1934, [vii], 17, 471; A., 3G9.20 Ann. Reports, 1932, 29, 23.21 I. R. Rao, Indian J . Physics, 1933,8, 123; A., 1934, 9 ; L. A. Woodwardand R. G. Homer, Proc. Roy. Soc., 1934, [ A ] , 144,129; A., 473; R. M. Bell andM. A. Jeppeson, J . Chern. Physics, 1934, 2, 711; A., 1289; L. M6dard, Compt.rend., 1933, 197, 582; A., 1933, 1102; L.MBdard and H. Volkringer, ibid., p.833; A., 1933, 1228.Chem., 1932, [B], 17, 233; A., 1932, 70624 GENERAL AND PHYSICAL CHEMISTRY.has been investigated in non-aqueous solvents and shown to bepresent as un-ionised molecules.22 The magnitude of the frequencyis found to depend upon the polar character of the solvent.The Raman spectrum of water continues to receive attention,in both the vapourZ3 and the liquid24 state. In particular, I. R.Rao concludes, from a study of the intensity distribution in theRaman bands at different temperature^,^^ that the degree of poly-merisation varies with temperature-a result which may be inter-preted in terms of recent theories of liquid water.26The power of the Raman effect as a method of chemical analysisis enhanced by the fact (see below) that many organic groups giverise to characteristic lines whose frequencies are more or less in-dependent of the rest of the molecule.This makes it possible touse the phenomenon to detect the presence or absence, not only ofmolecular species in a mixture, but also of particular groups withina molecule (see further below). The spectra of germani-chloroformand stanni-chloroform may be quoted as an example. These arefound27 to be similar to that of chloroform except for the absenceof a frequency attributable t o the linking of the hydrogen atom.The explanation advanced is that ionisation may occur for thegermanium and the tin compound.Raman Zffect and Restoring Forces in Molecules.-In the aboveapplications, the " molecular autograph " is used merely for identi-fication purposes, and no attempt is made to deduce character fromthe handwriting.The scope of application is widened by the ob-servation4 that many strong Raman frequencies are equal tofundamental vibration frequencies of the scattering molecule, asobserved in infra-red absorption or emission.The possibility of such changes of frequency had been foreseenas early as 1923 by A. Smekal,28 who gave a simple interpretationin terms of the extreme quantum theory. A light quantum ofenergy hv, impinges on a molecule, gives up the energy hv in settingthe molecule vibrating with frequency V, and is thereby scattered22 W.West and P. Arthur, J . Chem. Physics, 1934,2, 215; A., 583.23 D. H. Rank, ibid., 1933, 1, 504; A., 1934, 10.24 G. Bolla, Nuovo Cim., 1933, [ii], 10, 101; A,, 1934, 10; I. M. Magat,J . Phys. Radium, 1934, [vii], 5, 347; A., 1055; J. Cabannes and J. de Riols,Compt. rend., 1934, 198, 30; A., 238; I. R. Rao, 2. Physik, 1934, 90, 658;A., 1155.25 Phil. Mag., 1934, [vii], 17, 1113; A., 829; Proc. Roy.Soc., 1934, [A], 145.489; A , , 942; cf. G. B. B. M. Sutherland, ibid., 1933, [A], 141, 542; A., 1933,1103.26 See Ann. Reports, 1933, 30, 34.27 H. Volkringer, A. Tchakirian, and (Mme.) M. Breymann, Compt. rend.,2a Naturwiss., 1923, 11, 873.1934,199, 292; A., 942WOODWARD : THE RAMAN EFFECT. 25with the diminished energy hv, - hv = hv’.If the scatteringmolecule is originally vibrating, the incident quantum may pickup the energy hv and have its frequency increased. The magnitudeof the frequency shift (Raman frequency) is in either case v .Thus the Raman effect, with its relatively simple technique,provides a convenient method of photographing infra-red frequenciesby means of visible or ultra-violet light. It must be noted thatthere is, in general, a lack of correspondence between infra-red andRaman spectra as far as number of lines, relative intensities, etc.,are concerned; for it is not to be expected that the selection rules,etc. (see below), will be the same for such different processes. Thetwo methods must be regarded as complementary; and to obtainthe most complete information, corresponding infra-red and Ramanspectra must be taken together.A notable feature of the latter istheir relative simplicity, due to the fact (deducible from the completetheory-see below) that only fundamental vibration frequenciescan occur strongly, harmonics and combination frequencies beingrelatively very weak. In the sequel we shall deal only withfundamentals.In a comparatively few cases (molecules with small moments ofinertia) it is possible to observe the rotational fine structure ofvibrational Raman lines. Pure rotational Raman lines may alsobe observed on both sides of the line scattered without change offrequency. As with infra-red data, the rotational frequencies maybe used to calculate the moments of inertia of the scattering molecules.Further than this, the complete theory of the intensity distribution,etc., of the rotational lines, as worked out by G.Placzek and E.Teller,29 permits of deductions as to molecular symmetry. Theseauthors discuss the application of their theory to a number ofsimple molecules. Of recent experimental work in this direction,reference may be made to the investigations of C. M. Lewis andW. V. Houston,30 especially upon ammonia (supporting a flatpyramidal model) and methane (confirming the high symmetry).The amount of data on rotational Raman spectra is relativelysmall, since with most molecules the rotational structure is notresolved. Attention will therefore be confined to vibrationalfrequencies.Now the vibrational frequencies of a molecule of known structuredepend upon the masses of the oscillating atoms and the restoringforces called into action by the deformations of the molecule fromits normal shape.The masses being known, observation of thefrequencies in the Raman effect may therefore be expected to yield2. Physik, 1933, 81, 209; A., 1933, 446.Physical Rev., 1933, [ii], 44, 903; A., 1934, 12926 GBNERAL AND FHYSICAL CKXMISTRY.information as to the forces. In the very simple case of the diatomicmolecule, where there is only one (axial) vibration frequency, themotion may be assumed to be simple harmonic and the frequencymay be written as v = l / j z j Z x , where p is the reduced mass andf (the so-called force constant of the link) 31 is the restoring forceper unit displacement.Hence, from the observed value of the onefrequency, the one unknown f may be calculated. To the listof values of f for diatomic molecules32 there has recently beenadded l7 the value (1.68 x lo5 dynes per cm.) for the doublemercurous ion (Hg - Hg)+-l-.For a molecule of known structure containing more than two atoms,however, the number of unknown constants required to computethe nuclear vibrational frequencies is greater than the number ofobservables (ie., measurable frequencies), and so it is necessary tomake simplifying assumptions as to the nature of the forces concerned.The chief alternative sets of assumptions which have been used33are the central-force system and the so-called valency-force system.I n the former, an alteration of the distance between any two atomsin a molecule is assumed to bring into action a proportional restoringforce directed along the line joining the two nuclei.In the latter,on the other hand, it is assumed that restoring forces of the kind justmentioned are only exerted between atoms which are actuallylinked together in the formula of the molecule as usually written,and there is also the further assumption (not made in the central-force system) that an alteration of the angle between two bonds ofan atom calls into action a proportional force directed normally tothe bonds so as to oppose the deformation. Neither of thesesystems is completely successful in accounting for observed results 59 33a-a state of affairs that is not surprising since both certainly involvetoo great a degree of simplification.On the whole, however, itwould seem that the valency-force system, which corresponds moreclosely to accepted chemical views, is the more satisfactory.Very important additional information as to the forces betweenatoms in molecules is to be expected frcm the study of the changesin vibrational frequency resulting €rom the replacement of an atomby one of its isotopes. Such a replacement leaves the forcespractically unaltered, but the change of mass alters the frequencies31 A. Dadieu and K. W. 3'. Kohlrausch, Ber., 1930, 63, [B], 261; A,, 1930,33 Ann. Reports, 1931, 28, 401, top of Table I.3) First introduced by N. Bjerrum, Verhandl. deut. physikd. Ges., 1914,335 See, e.g., the recent applications to pwaffins, K.W. F. Kohlrausch arid663; cf. Ann. Reports, 1931, 28, 371.16, 737.F. Koppl, 2. physikal. Chew&., 1934, [B], 26, 209; A., 94227 WOODWARD THE RAMAN EFFECT.and so increases the number of observables. A. Langseth= hasshown that the isotopy of chlorine gives rise to a fine structure ofone of the lines of chloroform, and an effect observed in the Ramanspectrum of benzene has been ascribed35 to the presence of C13.Much bigger and more easily observable frequency changes areproduced, however, by the substitution of hydrogen by its heavierisotope deuterium, and results of the utmost importance may beanticipated from the study of these effects. Already, the Ramanspectrum of heavy water has been investigated both in the vapour 36and in the liquid 37 state, and preliminary results are published forheavy acetylene C,D, 38 and for a liquid which was thought to beheavy benzene C,D, .39Quite generally, a fundamental vibrational frequency vi of apolyatomic molecule may be expressed in the same form as before,wiz., vi = a / 2 x , and may be regarded as involving the periodicvariation of a certain so-called normal co-ordinate pi (the analogueof the distance between the atoms in the diatomic case).Theimportant points to note are that qi involves the relative positions ofall the atoms taking part, that fi involves all the forces between them,and that pi involves all the masses. Hence, the frequency v icannot, in general, be located in any particular part of the molecule,nor can fi be ascribed to any particular link : the whole moleculevibrates.Now the interest of the chemist is directed primarilytowards the force constants of particular links, and it would at firstsight appear hopeless to deduce these from the observed frequenciesof (say) a complicated organic molecule. I n actual fact, however,examination of a large number of organic substances has broughtto light many remarkable empirical simplifications. It appearsthat certain groups always give rise to their own characteristicRaman lines, the frequencies of which are more or less independentof the constitution of the rest of the molecule. We find in theRaman effect, as in other properties, that high degree of groupindividuality which is one of the main characteristics of organicchemistry.Many of the empirical regularities have been discovered in theextensive investigations of K.W. F. Kolilrausch and his collabora-a4 2. Physik, 1931, '72, 350; A., 1931, 1353.35 p. Grassrnann and J. Weiler, ibid., 1933, 86, 321; A., 1934, 10.36 D. H. Rank, K. D. Larsen, and E. R. Bordner, J . Chern. Physics, 1934,37 R. W. Wood, Physical Rev., 1934, [ii], 45, 392; A., 683; Nature, 1933,38 G. Gloclder and H. M. Davis, Physical Rev., 1934, 46, 535.39 J. W. Murray, C, I?. Squire, and D. H. Andrews, J. C?hem. P?bysics, 1034,2, 464; A., 1155.132, 970; A., 129; ibid., 1934, 133, 106; A., 238.2, 715; A., 128928 GENERAL AND PHYSICAL CHEMlSTRY.tors. A general account (up to 1931) is to be found in the book towhich reference has already been made,5 while later results aresummarised in two interesting general articles40 which K.W. F.Kohlrausch has recently published. To illustrate the kind ofrule which is found to hold, we may take as example *l the Ramanspectrum of isopropyl mercaptan (CH,),CH*SH. This is made upapproximately of (1) the characteristic lines (so-called inner groupfrequencies) of the respective groups SH, CH,, and CH; and (2)lines ascribable to the assemblages (CH,)*CH*( CH,) and (CH)*(SH),regarding (CH,), (CH), and (SH) as individual ‘( atoms ” of masses15, 13, and 33 respectively. The justification for this approximateway of regarding the molecule is based upon analysis and comparisonof the frequencies of a large number of compounds of known struc-ture. The inner group frequencies, as deduced by empiricalinspection of the spectra of different substances, are not exactlyconstant.In the particular case of SH, however, the constancyis very good (variations of less than 0.3% for different mercaptans).It becomes permissible, therefore, to regard this group as a’nindividual diatomic oscillator, and to work out an approximateforce constant for the stretching of the link. In other cases (e.g.,C:O, see below), the constancy is not nearly so satisfactory : theremainder of the molecule exerts a much larger constitutive influence.Nevertheless, an interesting list of approximate force constantsfor organic links may be added to the list for diatomic m0lecules.~2A notable result is obtained 43 by considering, instead of the forceconstant f, the mean restoring force K in the vibration. This isgiven by K = +fa, where a is the amplitude.It transpires thatthe K values for typical organic single, double, and triple links areapproximately in the ratio 1 : 2 : 3.A further approximate sub-division of vibrations 44 is into (1)so-called valency vibrations (v-type), in which the main displace-ment is a stretching of valency links; and (2) bending or so-calleddeformation vibrations (&type), in which the main displacement isan alteration of valency angles. Thus, two of the three frequenciesof (CH,)*(CH)*(CH,), considered as a non-linear ‘‘ triatomic ” assem-blage (see above), are of the v-type, and the third is of the &type.The characteristic CH frequencies also fall into the same two classes.40 Naturwiss., 1934, 22, 161, 181; A., 472; 2.Elektrochem., 1934, 40,429; A., 942; see also M. Bourguel, Bull. SOC. chim., 1933, [iv], 53, 469; A.,1933, 998.4 1 K. W. F. Kohlrausch, 2. Elektrochem., 1934, 40, 429; A., 942.42 See Ann. Reports, 1931, 28, 401, Table I.43 K. W. F. Kohlrausch, op. cit., p. 162.44 R. Mecke, Leipziger Vvrtrage, 1931, p. 23; 2. physikal. Chem., 1932, [B],16, 409; A., 1932, 559; ibid., [B], 17, 1; A., 1932, 675WOODWARD : THE RAMAN EFFECT. 29Considerations as to the approximate relative magnitudes of theforce constants of stretching and bending make possible 44 anallocation of frequencies, not only to particular groups in a molecule,but also to V- or &types.The quantity k introduced by R.Mecke (Zoc. cit.) to characterisethe ‘‘ rigidity ” of a linkage between two atoms differs from both theforce constant f and the mean restoring force K mentioned above.Mecke’s k, which shows remarkable regularities (e.g., is practicallyconstant for a series like the hydrogen halides), is defined as the workwhich would be expended in doubling the length of the link ifHooke’s law were obeyed. Consequently, the expression for thefrequency involves, in addition to k and the reduced mass p, thedistance r between the atoms concerned. To calculate k from anobserved frequency, it is necessary to know T , as determined bysome other method such as X-ray diffraction. Conversely, ifthe value of k be deduced from analogy to other similar compounds,then it is possible to calculate interatomic distances, etc., fromobserved frequencies.R. Titbi~a4~ has recently worked out molecularconstants for a number of organic compounds by this approximatemethod, and has obtained results in fair agreement with thosededuced by other methods.As t o the constitutive influence of the rest of the molecule upona frequency characteristic of a given group, a few examples(selected from a great mass of data) must suffice to indicate thesort of regularity observed. K. W. I?. Kohlrausch and F. KoppIS3find that the unbranched paraffins from C5H,, to C,,H,, give a&type frequency which falls progressively with increase of chainlength, and a v-type frequency which oscillates in magnitudeaccording as the number of carbons is odd or even.Anotherinteresting empirical regularity is observed in the contribution ofthe group CX (X = C1, Br, I) at the end of a hydrocarbon chain.It appears that this group can be associated in certain cases with asingle Raman h e , and in other cases with two lines close together.The doubling has been empirically related 46 to the possibility of‘( free rotation ” round the bond, although no such relation is to beexpected from theoretical considerations of a simplifiedThe recent interesting investigations of the freedom of rotationaround a single bond by S. Mizushima, Y. Morino, and K. Higasid5 Ann. Physique, 1934, [xi], 1, 533.46 K.W. F. Kohlrausch, 2. physikal. Chem., 1932, [B], 18, 61; A., 1932,897; ibid., 1933, [B], 20, 217; A., 1933, 446; cf. W. D. Harkins and R. R.Haun, J . Amer. Chem. SOC., 1932, 54, 3920; A., 1933, 7.4 7 E. Bartholorn6 and E. Teller, 2. physikal. Chem., 1932, [B], 19, 366;A., 1933, 11430 GENERAL AND PHYSICAL CHEMISTRY.will be dealt with below in connexion with molecuIar symmetry.K. W. F. Kohlrausch and collaborators 4* have investigated theC:O frequency in a number of different compounds of the typeX*CO*Y. If X is an alkyl group, then the C:O frequency is in-dependent of the nature of the chain, except for small changesproduced by alteration of the degree of branching at the cc-carbon.The biggest variations of the C:O frequency (up to 9%) are pro-duced by variation of the group Y attached directly to the C:Ogroup.The important point which emerges is that the effects ofthe groups introduced depend, not simply upon their masses, butrather upon fheir polar character^.^^ Hence it follows that the ob-served frequency changes are primarily related to changes in theforce constant of the C:O linkage, and not merely to changes in thereduced mass. Conjugation of the double bond of C:O with anotherdouble bond is found to cause an increase of intensity of thecharacteristic line.5o Such knowledge of the behaviour of theC:O frequency, together with other similar empirical rules, makesi t possible t o use the Raman effect to investigate such questions asketo-enol tautomerism 51 and the structure of anhydrides.52Special interest attaches to the empirical regularities which areobserved in the Raman spectra of benzene 35 and its deri~atives.5~The relationships between these and the regularities for aliphaticcompounds of known structure have recently been discussed by48 K.W. F. Kohlrausch and A. Pongratz, Monatsh., 1934, 64, 374; A.,1290; H. C . Cheng, 2. physikal. Chem., 1934, [B], 26, 288; A., 1056; ibid.,24, 293; A., 346; K. W. F. Kohlrausch and F. Koppl, ibid., p. 370; A.,473; K. W. F. Kohlrausch and A. Pongratz, ibid., 1933, [B], 22, 359, 373;A., 1933, 1228; K. W. F. Kohlrausch, F. Koppl, and A. Pongratz, ibid.,21,242; A., 1933,661 ; cf. G. R. Paranje and K. S . Savanur, Indian J . Physics,1934,8, 503; A., 1155.49 In this connexion, cf.M. Bourguel, Compt. rend., 1932, 194, 1736; A.,1932, 676.60 Cf. K. Matsuno and K. Han, Bull. C'hem. SOC. Japan, 1934, 9, 88; A.,473.61 K. W. F. Kohlrausch, 2. Elektrochem., 1934, 40, 429; A., 942; K. W. F.Kohlrausch, F. Koppl, and A. Pongratz, Anal. Pis. Quint., 1933, 31, 315;A., 1933, 998; T. Hayashi, Sci. Papers Inst. Phys. Chem. Res. Tokpo, 1933,21, 69; A., 1933, 764.6a K. W. F. Kohlrausch, A. Pongratz, and R. Seka, Ber., 1933, 66, [B], 1;A., 1933, 144.63 See, e.g., K. W. F. Kohlrausch and A. Pongratz, Monatsh., 1934, 64, 361 ;K. W. F. Kohlrausch, ibid., 1933,63, 427; A., 1934, 346; A. Dadieu, K. W. F.Kohlrausch, and A. Pongratz, ibid., 1932, 61, 426; A., 1933, 209; ibid., 60,253; A., 1932, 898; K. Matsuno and K.Han, Bull. Chem. SOC. Japan, 1934,9, 88; A., 473; ibid., 1933, 8, 333; A., 1934, 130; N. G. Pai, Nature, 1933,132,968; A., 129; J. W. Murray and D. H. Andrews, J . Chem. Physics, 1934,2, 119; A., 473; F. W. Crawford and J. R. Nielsen, ibid., p. 567; A., 1155WOODWARD : THE RAMAN EFFECT. 31K. W. F. Kohlra~sch,~~ who finds that the evidence favours theKekule formula for benzene. The arguments all involve theinterpretation of the Raman spectra of benzene derivatives in termsof characteristic group frequencies, constitutive regularities, etc.,deduced empirically from aliphatic compounds. Though thejustification of such an interpretation is perhaps doubtful, and thoughthe arguments taken singly would be unconvincing, the accumulatedempirical evidence is most suggestive.(Concerning the symmetryof the benzene ring, see below.)Similar considerations have been applied to the rings of pyrrole,55thiophen, and furan 56 by G. B. Bonino and his co-workers, who con-sider the data to accord best with a type of centric formula; butfrom an examination of the Raman spectra of compounds knownto have conjugated double bonds in a ring, R. Truchet and J.Chapron 57 conclude that the objection to the Kekuli! formula isover-ruled, and K. Matsuno and K. Han 58 likewise infer that thefuran ring contains double links. The effects of conjugation uponthe frequency associated with the C:C linkage have also beeninvestigated by T. H a y a ~ h i , ~ ~ L. Piaux,60 and others.It is interesting to inquire into the reasons for the observed highdegree of individuality of organic groups in respect to vibrationalfrequencies.Some idea, of the sort of factor which may occasionsuch individuality can be obtained from simple considerationsof the diatomic group X*Y in the molecule R-X*Y, where R representsall the rest of the molecule. If Y is of relatively very small mass(e.g., a hydrogen atom), its vibration will disturb the more massiveX very little. Consequently, the rest of the molecule which islinked to X will be, as it were, unawitre of the vibration of Y ; andconversely, the vibration of Y will be practically unaffected by therest of the molecule. Alternatively, if the linkage between X andR is relatively very weak, the extent to which the mutual vibrationsof X and Y influence R (and vice verst-c) will be very small.Passingto niore complicated cases, reference may be made to the work ofE. Bartholome and E. Teller,47 who, using a much simplified model,have been able to explain theoretically the individual behaviour ofa group such as CC1 at the end of a hydrocarbon chain.54 Naturwisa., 1934, 22, 184; A., 472.55 G. B. Bonino, R. Manzoni-Ansidei, and P. Pratesi, 2. physikal. Chem.,56 G. B. Bonino and R. Manzoni-Ansidei, ibid., p. 327; A., 830; 88e also5 7 C m p t . rend., 1934, 198, 1934; A., 830.58 Bull. Chem. SOC. Japan, 1934, 9, 327; A., 1155.68 Sci. Papers I n s t . Phys. Chem. Res. Tokyo, 1934,23, 274; A., 473.60 Corr~pt. rend., 1934, 199, 66; A., '352.1934, [B], 25, 348 ; A., 830.G. Glockler and B.Wiener, J. Chern. Physics, 1934, 2, 4732 GENERAL AND PHYSICAL CHEMISTRY.Ramn Effect and Molecular Symmetry.-In the applicationsoutlined above, the Raman effect is considered merely as providingfrequency values. The full information inherent in it cannot,however, be utilised without taking into account the other propertiesof the spectrum, such as number of lines, their relative intensities,states of polarisation, etc. A. Smekal’s extreme quantum explana-tion 28 is not coiicerned with the mechanism of the effect, and so tellsus nothing of these properties.Now, although the effect was not observed experimentally until1928,4 the complete theory of the mechanism of the interaction ofthe light and the scattering system had already been worked outin 1925 by H.K. Kramers and W. Heisenberg,61 using the cor-respondence principle ; in 1926 by E. Schrodinger,B2 using wavemechanics ; and in 1927 by P. A. M. D i r a ~ , ~ ~ using general quantummechanics. These theoretical treatments all agree in giving thesame final formula, from which all the properties of the scatteredlight may in principle be deduced. Unfortunately, the formulainvolves a summation, for which it is necessary to know all theenergy levels of the scattering system in question, as well as all theprobabilities of transitions between them. In very simple cases(diatomic molecules) the laborious summation can be carried out ; 64but the requisite data are in general lacking, so that the result(though of extreme theoretical interest) is a t present of no practicalvalue for the purpose of interpreting Raman spectra.Undoubtedly the greatest advance in this connexion, and onewhich has given a considerable impetus to experimental work, isG.Placzek’s polarisability theory. 65 This author has recentlypublished a complete account of the mathematical-physical treat-ments of the Raman effect of free molecules,66 to which referencemay be made for all details. A less thorough, but perhaps moreeasily readable account, is to be found in a lecture by J. Cabannes.67I n his polarisability theory, G. Placzek starts out from the con-sideration that, although the Raman frequencies are nuclear fre-quencies, yet the actual scattering of the light must be due practicallyentirely to the less massive electrons.Attention must therefore bedirected to the interaction between nuclear vibrations and the61 2. Physik, 1925, 31, 681.G3 Proc. Roy. SOC., 1927, [A!, 114, 710.64 J. H. van Fleck, Proc. Nat. Acad. Sci., 1929, 15, 754; C. Manneback,2. Physik, 1930, 62, 224; A., 1930, 840.e5 2. Phy&k, 1931, 70, 84; A., 1931, 893; Leipxiger Vortrage, 1931, 71.66 “Handbuch der Radiologie,” Vol. 6, Part 2, p. 205, Akademische67 ‘‘ La Structure des MoMcules et la Diffusion de la LumiAre,” Bermejo,62 Ann. Physik, 1926, [vi], 81, 109.Verlagsges., Leipzig, 1934.Madrid, 1932 (in French)WOODWARD : THE RAK4N EE’PECT. 33surrounding (‘ electron atmosphere.” In the first place, lightscattering without change of frequency (classical or Rayleighscattering) may be visualised as due to the periodic polarisation ofthe electron atmosphere by the oscillating electric field of the incidentlight waves, i.e., the production of an induced electric dipolemoment oscillating with the incident frequency v,.The propertyof the molecule governing this effect is its polarisability a, whichis representable by a sphere when the molecule is optically isotropicand by an ellipsoid when it is Optically anisotropic. The shape ofthis ellipsoid determines, in particular, the state of polarisation ofthe Rayleigh line, as measured by a suitably defined and experi-mentally accessible degree of depolarisation p. A nuclear vibrationof frequency v causes, in general, a corresponding periodic alterationof the polarisability a ; the ellipsoid is now no longer constant, butaltering (in shape, orientation, etc.) a t frequency v.As far as theoscillating electric moment induced by the incident light is concerned,this superimposes upon the periodicity V, a new periodicity V,and the two together give the frequencies v0 & v. These thereforeappear in the scattered spectrum, i.e., we have the Raman effect.It follows that, just as the Rayleigh line is characterised by thequantity a, so is a Raman line characterised by the rtlteration ofa caused by the respective nuclear vibration, i.e., by the quantity(am&),, where q is the normal co-ordinate of the vibration, and thesuffix zero denotes that the value of aa/aq is t o be taken at theequilibrium position of the nuclei. The general selection rule forRaman lines becomes a t once obvious : if a nuclear vibration issuch that it leaves a unaffected or causes it to pass through a maxi-mum or minimum as the nuclei pass through their mean positions,then (aa/aq),=O, and the corresponding line is forbidden in theRaman effect. Of course, these considerations tell us nothingabout whether the frequency in question is forbidden or permittedin direct infra-red absorption or emission, which are subject to quitedifferent selection principles.The intensity of a Raman line will be greatest when (&/aq), isgreatest, i.e., when the nuclear vibration most affects the ‘< electronatmosphere.” In the case where only one linkage is involved, itfollows that the intensity Will decrease with decrease in the degreeof electron sharing (i.e., with decrease in the homopolar characterof the link) and will finally vanish when the binding becomes com-pletely polar (i.e., when the “ electron atmospheres ” of the atoms-now ions-become independent).This is precisely the conclusionreached empirically by P. Krishnamurti 68 from systematic in-68 Nature, 1930,125, 892; A., 1930, 978; I n d i a n J . Phpics, 1930, 5, 113;A., 1030, 1344; cf. ibid., p. 633; A., 1931, 146.REP.-VOL. XXXI. 34 GENERAL AND PHYSICAL CHEMISTRY.vestigations of inorganic chlorides. Intensity measurements havebeen used by I. Hansen-Damaschun 69 as a criterion of the degreeof homopolarity of linkages in inorganic complexes.R. Samueland M. J. Khan 70 have also observed a quite different effect, vix.,that the magnitude of the CN frequency in complex cyanides appearsto increase with increase of homopolarity.The practical value of the polarisability theory as a source ofinformation upon molecular structure might, at first sight, appearto be small in view of the fact (see above) that it is not, in general,possible to calculate nuclear frequencies without introducingdoubtful simplifying assumptions as to the force systems. Actually,however, the theory goes on to make a number of fundamentaldeductions about the relation of Raman spectra to molecularstructure by arguments quite independent of the special nature ofthe forces involved. These deductions, which are of great practicalimportance, are based upon pure symmetry considerations.In the first place the total number (372 - 6) of fundamentalvibrational frequencies possessed by a molecule is determinedsimply by the number n of atoms it contains; and the number ofthese frequencies which have identical values (the degeneracy)is determined by the symmetry of the molecule considered as anassemblage of mass-points.Further than this, the molecularsymmetry determines the symmetry properties of the differentmodes of vibration, and these clearly decide the quality of thecorresponding variations of the polarisability a. But it is upon thisquality that the properties (e.g., states of polarisation) of thecorresponding Raman lines depend. Hence, for a molecule con-taining a known number of atoms, the structural symmetry deter-mines both the number N and the states of polarisation (p-values)of the Raman lines.Observation of N and the p-values thereforeprovides a powerful method of discriminating between differentpossible molecular symmetries. Considerations of space precludeany account here of the various rules of selection and polarisation,for details of which reference may be made to G. Placzek's treatise.66The practical application of the rules is facilitated by the completetables which are given there. The example of a triatomic moleculeXY, may serve to indicate the sort of deductions which the theorymakes possible. If the molecule gives only one Raman line, theintensity being high and p being < $, then the molecule must beSymmetrical and linear, viz., Y - X - Y.A symmetrical butbent molecule ( L e , , the angle between the two bonds of the centralX atom not equal to 180") would give three Raman lines, of which89 2. physikal. Chem., 1933, [B], 22, 97; A., 1933, 886.iO 2. Physik, 1933, 84, 87; A., 1933, 886WOODWARD : THE RAMAN EFFECT. 35two would have p < + and the third p = +. An example of amolecule for which the Raman effect data indicate this bent typeis sulphur dioxide. In his treatise, G. Placzek summarises theresults of the application of his theory to the above types, as well asto molecules of the formula XY, (pyramidal or plane), XY, (tetra-hedral), X,Y2 (acetylene, linear), XY,Z (three-fold axis), etc.The conclusions are always in agreement with those afforded by otherlines of inquiry.A notable complication may sometimes occur in connexion withthe number of Raman lines which appear.The best example iscarbon dioxide. This is known from other data to be a symmetricallinear molecule, and hence would be expected to give only oneRaman line (see above). Actually, however, the spectrum is found 7lto consist chiefly of two strong lines rather close together. Theexplanation of this apparent anomaly was given by E. Fermi,72who showed that the doubling is due to a fortuitous commen-surability between two of the fundamental vibration frequenciesof the molecule, one of which chances to be almost exactly twicethe other. In drawing deductions from the number of lines appearingin the Raman Ecpectrum of a, mulecule, it is necesaary to bear inmind the possibility of such a fortuitous increase, as well as the riskthat a line, though permitted, may Le so weak as to have escapedobservation.Measurements of thb degree of depolarisation p serve to supportand extend conclusions based on numbers of lines.Unfortunately,the experimental technique of accurate polarisation measure-ments 73 is incomparably more difficult than that of mere frequencydeterminations. However, data have been accumulated for afairly large number of compounds, thanks to such workers asS. Bhaga~antam,~~ J. Csbannes and A. R o ~ s s e t , ~ ~ P. Gras~mann,7~L. S i r n o n ~ , ~ ~ B. Trampy,77 S. Venkates~aran,'~ and others.An71 A. Langseth and J. R. Nielsen, 2. phy8ikal. Chem., 1932, [BJ, 19, 35;A,, 1932, 1188; I. Hansen, Physical Rev., 1934, [ii], 46, 122; A., 1066; mealso A. Langseth, J. U. Sorensen, and J. R. Nielsen, J . Chem. Physics, 1934,2, 402; A., 942.72 2. Physik, 1931, 71, 250; A., 1931, 1111; see also D. M. Dennison,Physical Rev., 1932, [ii], 41, 304; A., 1932, 982; A. B. D. Cassie and C. R.Bailey, 2. Physik, 1932, 79, 35; A., 1933, 6; G. P. Ittmann, Physica, 1933,13, 177.78 See, e.g., J. Cabannes and A. Rousset, Ann. Physique, 1933, EX], 19, 229;A., 1933, 446.74 Indian J . Physics, 1932, 7 , 79; A,, 1932, 793.76 2. Physik, 1932, 77, 616; A., 1932, 1075.76 Cornm. Phgs.-math. SQC. A%& Fennka, 1932, 8, No. 13, 1.7 7 2. Physik, 1934, 88, 226; A., 583; ibid., 1934, 90, 133; A., 1066.78 Phil.Mag., 1933, [vii], 15, 263; A,, 1933, 33736 GENERAL AND PHYSICAL CHEMISTRY.interesting suggestion for the simplificatlioii of the technique ofpolarisation measurements, originally put forward by G. Placzekand W. R. van Wijk,79 has been applied by L. S. Ornstein and P.Stoutenbeek.80 The reversal or non-reversal of the direction ofpolarisation when the incident light is circularly polarised isalso explained by the polarisability theory,66 and measurements ofthis effect can be used as additional evidence of molecular symmetry.Amongst recent work, mention may be made of investigationsupon the hexafluorides of sulphur 82 and other elements,83 whichsupport an octahedral model. This is in harmony84 with theconclusions from earlier work 85 upon other systems of the typeX Y , .D. M. Yost and J. E. Sherborne 86 have recently obtainedthe Raman spectrum of arsenic trifluoride, for which the selectionrules indicate a pyramidal structure. The polarisation measure-ments of A. Langseth, J. R. Nielsen, and J. U. Sorensen 87 upon theazide and the thiocyanate ion give evidence for a linear structurein both cases, the former being centrally symmetrical. Of specialinterest is the evidence obtainable as to the symmetry of the benzenering. Perhaps the most remarkable fact in this connexion, pointedout by G. Placzek,88 is that the experimental data for liquid ben-zene are incompatible with the presence of a centre of symmetry.The whole question of the benzene ring has recently been consideredby J.Weiler,89 who concludes that the data provide support for athree-fold symmetry (such as would be given by the Kekul6 formula)rather than for a six-fold symmetry (such as must result if the ringis plane and all the carbons are equivalent). Reference has alreadybeen made to the work upon heterocyclic rings,W 66 which alsoinvolved some symmetry considerations.An interesting deduction concerning simple cis- and trans-'* 2. Physik, 1931, 67, 582; A., 1931, 408.8O Ibid., 1933, 85, 754; A., 1933, 1228.81 W. Hanle, Physikal. Z., 1931, 32, 686; A., 1931, 997; Ann. Physik, 1931,[v], 11, 885; A , , 1932, 108; {bid., 1932, [v], 15, 345; A., 1933, 114; R. Biir,Helv. Physica Acta, 1931, 4, 130; P.Daure, Compt. rend., 1934, 198, 725; A.,346.aa A. Eucken, H. Ahrens, E. BartholomB, and L. Bewilogua, 2. physilcal.Cltem., 1934, [B], 26, 297; A., 1055.B8 D. M. Yost, C. C. Steffens, and S. T. Gross, J . Chem. Ph98k, 1934,2, 311 ; A., 830.** 0. Redlich, T. Kurz, and P. Rosenfeld, ibid., p. 619; A., 1166.85 Idem, 2. physiknl. Chem., 1932, [B], 19, 231 ; A., 1933, 113.8 8 J . Chem. Physics, 1934, 2, 125; A., 473.87 2. physikal. Chern., 1934, [B], 27, 106.88 Ref. (66), p. 334.8D 2. Physik, 1934, 89, 58; A., 716; but cf. E. B. Wilson, P?iy&al Rev.,1934, [ii], 46, 146SIDGWICK : RESONANCE AND CO-ORDINATION OF HYDROGEN. 37isomerides can be drawn 66 from the symmetry theory, vix., thatthe centre of symmetry of the trans-form must result in fewerRaman lines for this isomeride than for the cis-form.This isborne out by e~periment.~~ B. Trumpy 77 has also measuredthe polarisations of the lines of the cis- and trans-isomerides ofdichloro- and dibromo-ethylene and found them to agree with thetheory.Similar symmetry considerations underlie the recent iiwestig-ations of S. Mizushima, Y. Morino, and K. Higasi 91 upon the freedomof rotation around the C-C link in s-dichloroethane. Starting fromthe idea that alteration of the relative positions of the two chlorinesby rotation, though considerably altering the intensities of certainRaman lines, may not appreciably affect their frequencies, theseworkers have made measurements of the ratio of the intensitiesof two of the Raman lines of this compound in various solvents.They find that the ratio shows a regular variation with the dielectricconstant of the solvent. Actually, the observed differences arenot large, and further confirmation of the effect is desirable.Theresult, which is brought into relation with similar regularities inthe observed dipole moment, is explained by the authors as due tothe different relative times spent by the molecule in configurationsapproximating to those in which the chlorines are in the cis- and thetrans-position respectively. L. A. W.3. THE THEORY OF RESONANCE AND THE CO-ORDINATION OFHYDROGEN.The theory of resonance in structural chemistry has already beendiscussed in these Rep0rts.l Recent work has established it on afirmer basis, and it must now be taken seriously into account byorganic as well as by physical chemists.Only a brief summarywill be given here, sufficient to make it possible to understand itsapplication to the co-ordination of hydrogen.It can be shown that if two electronic structures are possible forthe same molecule, the wave-mechanical function for the normalstate of the molecule is not either of those expressing the twoseparate states, but a linear combination of the two. This means thatthe molecule in question must be regarded either as passing fromone state to the other with very great frequency (some 1015 times persecond), or more probably as ha,ving a structure intermediatebetween the two, which cannot be expressed by the symbols ofA. Dadieu, A.Pongratz, and I<. W. F. Kohlrausch, Monatsh., 1932, 60,406, 221 ; A., 1932, 898.Q1 Phyaikal. Z., 1934, 35, 905.1 C. N. Hinshelwood, Ann. Reports, 1932, 29, 17; 1933, 30, 4438 GENERAL AND PHYSICAL CHEMISTRY.structural chemistry. The conditions for such resonance to bepossible are (1) that the two structures do not differ greatly in energy,and (2) that the atoms occupy practically the same positions inboth; the change, if there is one, is far too rapid for the atoms,even hydrogen atoms, to move with it. As a result of this resonancethe molecule will show the properties of both structures, but indifferent degrees, the form with the larger energy content (smallerstability) having the less influence. Two further consequences ofimportance for detecting the occurrence of the phenomenon are (1)that the heat of formation of the molecule, and hence also itsstability, is greater than that of either structure, and (2) that thedistances between the linked atoms are somewhat smaller.Theconception of resonance is originally due to Hund, but its applicationto molecules has been largely the work of Pauling and his school;some of the more important references areAs an example we may fake carbon dioxide, There are threepossible structures, the last two being identical :oz=c===O o+--c&-o o-sC-+o Obs.{ 2-56 2.56 2.56 2.30348 ca. 350 ca. 350 3801-28 1.28 1-43 1-13 1.13 1.43Distance, A.U. c--y--l -+ vHeat of formationfrom atoms, kg.-cals.}If we may assume that the length and the heat of formation of aco-ordinate link are the same as those of a normal covalency (whichis probable, though the evidence is not so strong as could be wished),the heats of formation of the three forms are nearly the same;they are all linear molecules, and the distances vary only to the smallextent caused by the change in the multiplicity of the link.Thusthe essential conditions of resonance are satisfied, and we shouldexpect i t to occur. If it does so, the heat of formation of carbondioxide should be greater, and the lengths of the links less, thancorresponds to the structure O=C=O. The values to be expected forthe three forms are given beneath the formula; the observedz L. Pauling, J. Amer. Chem. SOC., 1931, 63, 3225 (one-electron links).a Idem, ibid., 1932, 64, 988, 3570 (resonance of covalent and electrovalent4 Idem, Proc. Nut.Acad. Sci., 1932, 18, 293, 498 (interatomic distances).links).L. Pauling and D. M. Yost, ibid., p. 414; L. Pauling and J. Sherman,J. Chem. Physics, 1933, 1, 606 (heats of formation).L. Pauling and G. W. Wheland, ibid., p. 362; L. Pauling and J. Sherman,ibid., p. 679 (application to aromatic and hydroaromatic compounds). ' G. W. Wheland, &id., p. 731 (keto-enols).L. 0. Brockway and L. Pauling, Proc. Nut. Acad. Sci., 1933, 19, 860;N. V. Sidgwick, Trans. Faraday SOC., 1934, 30, 801 (organic azides).* L. E. Sutton, ibid., p. 789 (dipole moments and resonance)SIDGWICK : RESONANCE AND CO-ORDINATION OF HYDROGEN. 39C-0 distance is 1.15 A.U. instead of the 1.28 required for C=O,4and the heat of formation is 32 kg.-cals.greater than that calculatedfrom the value for a carbonyl group in aldehydes and ketones.6 Inthe papers quoted above, many other examples are given, in whichthe resonance is indicated by the heats of formation or the inter-atomic distances, or in some 49 % by the electrical dipole moments.This last criterion is of peculiar interest, because i t enables us todistinguish between resonance and tautomerism in its ordinarysense. In many molecules, as in nitrous oxide and the organicazides, the two structures have considerable but oppositely directedmoments, and the observed moment is very small. The opposingmoments of the two forms can only neutralise one another if theirtime of change is less than that required for the turning of the polarmolecule in the electric field, which is of the order of 10-l2 second.lOI n resonance, where the time of change (if we consider a changeas occurring) is of the order of s e ~ o n d , ~ this condition is ful-filled.But a mixture of the two forms in chemical equilibrium (atautomeric mixture) would change much more slowly, and musthave a moment which is a weighted arithmetic mean of the separatemoments, since the direction (with respect to the molecule) willnot affect the polarisation, which depends on the square of themoment.Familiar examples of resonance are afforded by the symmetry ofthe -N< group (indicated by the dipole moments), of the-C' ion, and of the NO,' and CO," ions.The crystallographicevidence shows that the last two are plane structures, as is requiredby the tetrahedral theory for the formulae (I) and (11), but further,00 0'0'0 o=c/ (11.)'0that the three oxygen atoms are at the points of an equilateraltriangle, with the nitrogen or carbon a t the centre. This implies aresonance, with the double link not localised on any particularoxygen atom. Here, too, we find the characteristic shortening ofthe link. The values are : for NO,', N-0 1-36, N=O 1.22 (mean1-31), obs. 1.23; for C03", C-0 1.43, CIO 1-28 (mean 1*38), obs.1-23 ,&.U.11 A further example is the " oscillation " of the ioniccharge in the ions of the triphenylmethane and the cyanine dyes,which seems to be the cause of their intense colours.lo P.Debye, Trans. Farachy Soc., 1934,30, 679.l1 V. M. Goldschmidt, Freudenberg's " Stereochemie," 1933, p. 5040 GENERAL AND PHYSICAL CHEMISTRY.The resonance theory of structure, if, as seems probable, it is to beaccepted, is a most important advance in the theory of structuralchemistry. It shows that the behaviour of a compound can oftennot be expressed by a single formula, but only by the combinationof two, and this, not in the tautomeric sense that the substance is amixture of two kinds of molecule, but in the sense that everymolecule has, a t least to some extent, all the properties representedby the two structures, as well as other properties which are directlydue to the resonance, especially an increase of stability, which ensuresthat the resonance will always occur when it is possible.It is to bepresumed that the modern organic theories which ascribe thereactivities of molecules to drifts of their linking electrons, are to beinterpreted with reference to the theory of resonance.Co- ordination of Hydrogen.As was pointed out in last year’s Report,12 the evidence accumu-lated in recent years has strengthened our belief in the occurrenceof this co-ordination-in the power of the hydrogen atom to holdtwo other atoms together-but it has also shown that the originalsuggestion, that such a hydrogen atom has four shared electrons,is untenable. The solution of the difficulty is provided by thetheory of resonance, the hydrogen being covalently attached toone and the other of the two atoms in the two structures. Thisimplies that the distance between the two atoms linked by the hydro-gen is shorter than in either of the separate structures, which isfound to be the case.In solid sodium hydrogen carbonate, forexample, the shortest distance between two oxygen atoms ofdifferent CO, groups, where there is no linking hydrogen, is 3.15 B.U. ;the insertion of a hydrogen atom t o form 0-H 0, if there were noresonance, should a t least not shorten this, whereas the observeddistance between the oxygen atoms in 0-H - - 0 is only 2.55 B.U.13The heats of formation of the two forms would not be expected todiffer greatly, since they only involve a rearrangement of the bondsbetween the same atoms ; the extra energy caused by the resonanceis shown by the stability of the co-ordinated form.The conditionsof resonance are therefore present, and we have to consider whatthe various resonating structures are. They may be divided intotwo classes, (I) those in which resonance can occur without ionisation,which implies that the co-ordinated structure is cyclic, and (11)those in which ionisation is involved.(I). If the hydrogen atom can be linked without ionisation toeither of the two atoms that it holds together (which for simplicityla Ann. Reports, 1933, SO, 112.W. H. Zschariasen, J . Chem. Physics, 1933, 1, 634SIDGWICK : RESONANCE AND CO-ORDINATION OF HYDROGEN. 41we may suppose to be oxygen), these two atoms must be part ofthe same molecule, and a rearrangement of links must take placealong the chain, which will be joined through the hydrogen to forma chelate ring.The process may involve one molecule (Ia) or two(Ia). It occurs within one molecule in the ordinary chelationthrough hydrogen, as in the lieto-enols or the o-aldehydophenols :( I bThe strain in a 6-ring with two double links is very small, andhence the same position of the atoms fits either structure. Thismechanism explains the symmetry of the ring, and the fact thattwo isomeric enols of this type have never been isolated. I n theo-phenol derivatives the second forin is o-quinonoid; if we assumethat in the benzenoid form the chelate 6-ring fixes the double linkbetween the atoms common to both rings,14 it will be seen that theother two double links in the aromatic ring have the same positionsin both structures, which is supported by the recent results ofW.Baker.15 We can also see why the tendency to chelationpractically disappears when the p-keto-enols are reduced t o p-keto-alcohols, R*CH(OH)*CH,*CO*R1, since the migration of the doublelink from one oxygen to the other is no longer possible, and a co-ordination of the hydrogen can only occur as it does in the alcohols(see 11, below) where the resonance energy is much weaker.(16). Sometimes this ring-formation can occur only by the com-bination of two molecules. This is what happens with carboxylicacids l6 and with oximes. Both these classes readily polymeriseto double molecules but no further, the co-ordinating power beingthereby exhausted.In the oximes, the second form must have theimino-structure, from which the N-ethers are derived :R 0-H R R O HR H-O/N=C<R and(11). To explain the association of simple hydroxylic compounds,such as water, alcohols, and phenols, where the co-ordination ofthe hydrogen will give chains and not rings, some other mechanism1* W. H. Mills and I. G. Nixon, J . , 1930, 2510.l6 J., 1934, 1684.Ann. Reports, 1933, 30, 115.B 42 OENEXAL AND PHYSICAL CHEMISTRY.must be found. It is well known that, in high di1ution;moleculesof this kind are less polymerised than carboxylic acids or oximes,but that with rising concentration the polymerisation increasesindefinitely, and can go far beyond the dimeric stage.17 This mustoccur through the formation of oxonium ions :R + RH-O/ H-O/ R and H-Q<H o/RThe simple molecules will be held in the positions required for theoxonium formation by the energy of the resonance.It is clearthat this process can be extended indefinitely through a series ofmolecules, giving as the ionised form :(For simplicity the atoms are here arranged on the plane model;actually, of course, the steric relations will be more complicated.)So long as the addition of another ROH molecule causes an increasedevolution of energy, the chain will be able to lengthen, but thetendency of the thermal agitation will be to break it up, and anequilibrium will be reached in which the degree of association willbe greater the lower the temperature.It will be seen that, in achain of this kind, all the ROH molecules other than those at theends are in the same state as a free ROH, except that their relativepositions are determined by the resonance, and presumably theyare brought nearer together than if the resonance did not occur.This gives us a picture of the state of hydroxylic liquids very like the“ pseudo-crystalline ” state suggested for liquid water by J. D.Bernal and R. H. Fowler ; 18 it is obvious that in water itself thereare further possibilities of resonance which do not occur when oneof the hydrogen atoms is replaced by an alkyl radical. The theoryexplains many of the properties of water and hydroxylic compoundsin general. It will be seen that the RH,O’ and OR‘ ions are notfree so long as the resonance persists; the whole chain forms a“ zwitterion,” and cannot contribute to the conductivity; this willbe due only to those ions which are displaced from the chain by thethermal agitation.Thus the minute conductivity of pure water isquite in accordance with the theory, which also exphins why theIT See, e.g., F. S. Brown and C. R. Bury, J. Physical Chem., 1926, 30, 694;A., 1926, 675.J . Chem. Physics, 1933,1, 515; A., 1934, 13; Trane. Paraday Soc., 1933,29, 1049; A., 1933, 1106SIDGWICK: HEATS OF FORMATION IN HOMOLOGOUS SERIES. 43number of free ions grows larger as the temperature, and hence thekinetic energy of the molecules, increases.The structure of the chains makes it possible, as Bernal and Fowlerhave pointed out, to account for the abnormal mobility of hydrogenand hydroxyl ions.As the temperature rises, the chains will onthe average become shorter, and this abnormality should diminish,as in fact it does : the mobility of the hydrogen ion is six times asgreat as that of the potassium ion at O", but only four times as greata t 50".Co-ordination of hydrogen with atoms other than oxygen, as in[F-HtF]' and in undissociated R,NH+OH, can obviously beexplained in the same way.If this theory is adopted, it clearly gives quite a different mech-anism for the co-ordination of hydrogen from that generally acceptedfor the co-ordination of other atoms, such as those of the metalsin the (3-diketone derivatives. The reason why the same compounds,such as the p-keto-enols, give rise t o both classes of derivatives isthat the shape of the molecule allows of the formation of a nearlystrainless ring.The difference in the mechanism of the linkagemay explain why certain molecules, such as ethylenediamine andglycollic acid, form chelate rings through metallic atoms, but notthrough hydrogen. The remarkable and regular variation in thepower of a hydrogen atom to co-ordinate, according t o the atom withwhich it is united (H-F > H-0 > H-N > H-C; H-F > H-CI;H-0 > H-S), must be due, in part a t least, to a difference in thereadiness with which the resonance occurs, Le., in the stability of thesecond (ionised) form. The view that the co-ordination of hydro-gen is due to a different mechanism from that of a metal is supportedby the work on absorption spectra by R.A. Morton, A. Hassan, andT. C. C a l l o ~ a y , ~ ~ who conclude that '' chelation through hydrogenof the mono-enol [of a (3-diketone or @-keto-ester], if it occurs a t all,must be different in kind from the chelation which obtains with' metallic derivatives. " N. v. s.4. HEAT$ OF PORMATION IN HOMOLOGOUS SERIES.F. D. Rossini 1 has recently determined the heats of combustionof the lower normal pa affins and primary alcohols with an accuracygreater than that hitherto attained, the errors (per g.-mol.) notexceeding 150 cals. per carbon atom. The results are surprising, andof great interest.If Q is the heat of combustion per g.-mol. of a substance, and Pthat of its carbon and hydrogen (and other elements, if any), these19 J., 1934, 900.1 Bur. Stand. J. Res., 1934, 12, 735; 13, 21, 18944 GENERAL AND PHYSICAL CREMISTRY.being taken as graphite, hydrogen gas, etc., then H f , the heat offormation of the compound from .these elements, is equal t oP - &. If we further know the heat Hat. required to convert thesequantities of graphite, hydrogen gas, etc., into their atoms, then. theheat of formation of 1 g.-mol. of the compound from its componentatoms Ha = Hat. + P - &; Ha is the total energy evolved in theformation of all the links in the molecule, and obviously this energy,or the stability of the molecule, will be greater the smaller the heatof combustion &.It was previously supposed that the heats of combustion (andhence also the heats of formation) of the paraffins showed a constantincrease per CH, from methane upwards; this implied that theheat of formation was strictly additive for the links, being of theform xA + yB, where x and y are the numbers in the molecule,andA and B the heatsof formation, of the C-C and the C-H linksrespectively. Rossiiii has shown that this is true when n, the numberof carbon atoms, is greater than 5, but that as we descend the seriesbelow this, the heat of formation becomes increasingly greater thanwould be expected, the value for methane showing an excess of4.8 kg.-cals.With the alcohols, he finds the opposite effect:where n is more than 5 , the additive rule again holds, with the sameincrement per methylene group as in the paraffins, but in the lowerhomologues the heat of formation becomes increasingly less, andthat of methyl a81cohol is 4.2 kg.-cals.smaller than the rule requires.Since the heats of combustion are far more accurately known thanthe heats of atomisation of the elements, the values quoted beloware the observed departures of the heats of formation Ha from thosecalculated on the additivity rule; these are independent! of theheats of atomisation assumed for the elements. The measurementsare made a t 25", and are calculated for the compounds in the gaseousstate. Rossini has also calculated, by means of the specific heats,the departures a t the absolute zero. These results are given inthe table, the experimental error being added for the first series :it is much the same in the others.Differences (obs.- calc.) in heats of formation far the gaseous state,in kg.-cals. per g.-mol.No. of Paraffins. Alcohols.C atoms. 25OC. oo K. 25' C. 0" K.1 + 4.61 & 0.1 -k 4.81 - 4.18 - 3.782 + 1.59 0-2 + 1-59 - 1.18 - 1.183 + 0.83 f 0.3 $- 0.84 - 0.60 - 0.604 + 0.46 -+ 0.4 + 0.47 - 0.30 - 0.305 + 0.13 f 0.5 + 0.15 - 0.15 - 0.156 0 f 0.7 0 0 010 0 f 1.2 0 0 & 1.3 015 0 &- 1.8 0 - SIDGWICK: HEATS OF FORMATION IN HOMOLOGOUS SERIES. 45The values a t 25" are plotted against n in the fig.; the radii ofthe small circles indicate the probable errors.These results account for a difficulty which has long been evidentin the heats of formation of homologous series, that the incrementper methylene group appears to be smaller in the paraffins thanin any of their substitution products.The difference is not large,being about 2 kg.-cals. per CH,, and so of the same order as the usualexperimental error; but its existence seemed certain. It was, ofcourse, obtained on the assumption that an additivity rule heldin each series, and was mainly derived from the values for the lowermembers, where the experimental errors are smaller. It is ob-vious from Rossini's figures that for the lower members the increase+ 4.0w 8 +2.0F p o&- 2.0I9??- 4-01 2 3 4 5 6 8 70 12Number o f carbon atoms,per methylene group is less in the paraffins and more in the alcoholsthan the common value for the higher members of both series.Since it was previously found that, whatever X may be in C,H,, + ,X,the increment is practically always greater than in the paraffins,we may expect that any other series of alkyl derivatives whenexamined with the same care will be found to give a curve of thealcohol type.Various causes which might lead to this peculiarity of the par-affis had been discussed before,2 and it was concluded that onlytwo are possible.One is that it is due to differences in the rotationalenergy, the heats being referred to the ordinary temperature in-stead of the absolute zero, though it is improbable that this couldaccount for so large a difference. This suggestion has been definitelydisproved by Rossini's calculation of the values at the absolutezero, since the abnormalities are practically the same there as a t2 N.V. Sidgwick, " The Covalent Link," 1933, p. 11646 GENERAL AND PHYSICAL CHEMISTRY.25". The other possible explanation, which seems the only oneleft, is that the symmetry of the methane molecule causes an addit-ional stability, and that this is interfered with when a C-H link isreplaced by a C-CH,, but more seriously when it is replaced by aC-0-H; so that we get an initial excess in the heat of formation inthe first case and an initial defect in the second, both of whichgradually disappear to give a common value as the molecule becomespredominantly composed of methylene groups. A quantitativephysical explanation of this effect of symmetry is much to be desired.These effects are, of course, small-the absolute value of theheat of formation of a C-H link is about 92 kg.-cals., while thedifference per C-H in methane is 1.2 kg.-cals., or less than 1*5y0-but they are large enough to make the calculation of the heats ofother links very uncertain when we only know the heats of com-bustion of the lower members of a series, and these, as Rossini'sresults have shown, are not very accurate.For instance, if we tryto find Ha for C-0-H by subtracting the value for C,H,, + , from thatfor C,H,, +,OH, the difference where n = 1 will be 8.8, and wheren = 2, 2.8 kg.-cals., larger than in the higher members of theseries. Rossini's work shows that no exact calculations of the heatsof linkage can be made until the heats of combustion in generalhave been redetermined with greater accuracy.In this connexion it should be noticed that recent determinationsof the heats of atomisation of nitrogen indicate that the usuallyaccepted value of about 208 kg.-cals.per mol. is some 20% toolarge ; from spectroscopic measurements, R. S. Mulliken 3 gets 168.3kg.-cals., and G. Herzberg and H. Sponer4 find an almost identicalvalue of 169.3. N. v. s.5. CHEMICAL KINETICS.A chemical change within a molecule or between two moleculesinvolves electronic transitions which are subject to the quantumlaws, The point has now been reached in the development of thesubject of reaction velocity where a beginning can be made in theinterpretation of experimental data, on wave-mechanical principles ;conversely, it appears not unlikely that the chemical data on morecomplex molecules may assist the physicist in arranging energystates which are too complicated for mathematical treatment.By a new graphical illustration applied to simple types of molecule,such as Y-shaped ones XR,, J.E. Lennard-Jones 1 has shown howthe physicist can picture the dissociation of the molecule into2. physikal. Chem., 1934, [B], 26, 1; A,, 960.Proc. Roy. Soc,, 1934, [A], 146, 242.a Phpical Rev., 1934, 46, 14447 BOWEN : CHEMICAL KINETICS.X + R, or X + R + R. The products and the probability ofthe decomposition are seen to depend on the energy. Of thegreatest interest in this connexion is the demonstration of P. Patatthat the formaldehyde molecule decomposes photochemically intoCO + H2 in the longer-wave region of the absorption band, butgives hydrogen atoms in the shorter-wave region.These results arein qualitative agreement with the most recent interpretation ofthe absorption spectrum of gaseous f~rmaldehyde.~ It is not yetpossible to form so clear a picture of the photochemical decompositionof more complex carbonyl compounds. The lzeten molecule,CH,=CO, decomposes photochemically into carbon monoxide andethylene apparently by a predissociation process : 4CHZ-CO + hv + CH2=COx -+ CHZ =CO --+- CH2 + COYbut the nature of the excited levels involved awaits explanation.The homogeneous thermal decomposition of this molecule is of acomplex nature.5 Of greater difficulty is the interpretation of thephotochemical decomposition of aldehydes and ketones.The spectraof acetaldehyde, propionaldehyde, and acetone each show two over-lapping regions of absorption, the first being of discrete or diffusestructure, and the second continuous, as far as can be seen. Thisdouble structure is most clearly shown by acetone, where it appearsthat fluorescence takes place only from the discrete region, and notfrom the continuum.6 A similar differentiation through fluorescencein the case of the other carbonyl compounds is less certain owing tooverlapping of the regions. The excited levels involved, which wewill call A levels, have not yet been interpreted, but they do notappear to be directly chemically reactive. In the liquid or dimolvedstates no gaseous photo-products are formed, but other chemicalreactions occur with a quantum efficiency which is less the higherthe concentration of the carbonyl compound.' Similar observationshave been made in the case of dicarbonyl substances.* This ismost readily explained by the non-reactivity of molecules in theprimary excited levels A , their capability of deactivation by collision2.physikal. Chem., 1934, [B], 25, 208; A., 740.a G. H. Dieke and G. B. Kistiakowsky, Physical Rev., 1934, 45, 4.* R. G. W. Norrish, H. G. Crone, and (Miss) 0. Saltmarsh, J . , 1933, 1533;A,, 1934,156; see also A,, 976; W. F. Ross and G. B. Kistiakowsky, J . Amer.Chem. Soc., 1934, 56, 1112; A., 740.A. T. Williamson, ibid., 1934, 56, 2216.6 R. G. W.Norrish, H. G. Crone, and 0. D. Saltmarsh, J., 1934, 1466;A., 1184; C. I?. Fisk and W. A. Noyes, J . Chem. Physics, 1934,2, 654; w . A.Noyes, A. B. F. Duncan, and W. M. Manning, ibid., p. 717.7 E. J. Bowen and E. L. A. E. de la Praudibre, J., 1934, 1503.* E. J. Bowen and A. T. Horton, ibid., p. 150545 GENERAL AND PHYSICAL CHEMISTRY.with normal molecules, and their passage (spontaneously or throughcollision with solvent molecules) into chemically reactive levels B.These reactive levels of ketone molecules in solution are powerfuldehydrogenating agents, as shown by their action on alcohols. Thealcohol is oxidised to aldehyde and the ketone molecule is reduced.If free oxygen is present, the alcohol is oxidised as before, but theketone is not reduced.The mechanism of these reactions has beendiscussed by H. L. J. Ba~kstrom.~ The quinone molecule alsopossesses oxidising properties in its excited states.10 In the gaseousstate, owing to the slower collisional rates, the primary excitedlevels A of carbonyl and dicarbonyl compounds have time to pass(directly or indirectly) into other levels, C, which form gaseousproducts by unimolecular decompositions.11T. G. Pearson l2 has shown, by the use of metallic mirrors, thatfree methyl groups are probably produced in this photodecompositionof gaseous acetone, methyl ethyl ketone, and diethyl ketone, butthat neither methyl groups nor free hydrogen atoms are producedfrom acetaldehyde, propionaldehyde, or methyl butyl ketone. Attemperatures above 80°, however, the kinetics of the photolysis ofacetaldehyde change completely, chains being set up, and the ratebecoming proportional to the square root of the light intensity.13Under these conditions methyl radicals may take part in the chainmechanism.These radicals are incapable of initiating chains inacetone at temperatures below 400°, so that the photodecompositionat ordinary temperature is probably not a chain reacti0n.1~ Furtherwork is still required before a composite picture can be presentedof the photoreactions of carbonyl compounds. One of the difficultiesis to account for the apparently continuous absorption spectra ofthese substances even at low pressures, which can hardly be dueto photodissociation, since the quantum efficiency is less than unity.Reference may also be made to another photochemical reactionwhich illustrates how chemical investigation may provide some in-formation about the nature of an excited level.The photo-oxidationof rubrene l5 is not a chain reaction, as are so many oxidations, and9 2. physikal. Chem., 1934, [B], 25, 99; A., 611.10 A. Berthoud and D. Porret, Eelv. Chirn. Acta, 1934, 17, 694; D. Porret,11 R. G. W. Norrish and M. E. S. Appleyard, J., 1934, 847; A., 852; cf.l2 J., 1934, 1718.18 J. A. Leermakers, J. Amer. Chem. Xoc., 1934, 56, 1537; A., 976.14 Idem, ibid., p . 1899; A., 1184; 3’. 0. Rice, E. L. Rodowskas, and W. R.1 5 E. J. Bowen and F. Steadman, J., 1934,1098; A., 977; see Ann. Reports,ibid., p . 703; A., 976.Ann. Reports, 1933, 30, 48; 1932, 29, 48.Lewis, ibid., p.2497.1932, 29, 173BOWEN : CHEMICAL KINETICS. 49is inhibited, not by " anti-oxygens," but by bases. This mayindicate that the reactive level is of the nature of an acid, having aloosened proton rather than a loosened hydrogen atom.The concept of a limited number of different activated states,each with its own specific reactivity, in unimolecular thermal gaseousreactions, recently put forward by C. N. Hinshelwood l6 has beenfound to afford a good explanation of the kinetics of the decomposi-tions of the series of molecules HCHO, CH,*CHO, C,H,*CHO, andCC1,*CH0.l7 The hypothesis can be pictured as the production ofreactivity through the elongation by vibration of a particular bondby different types of interference between the normal modes ofvibration of the molecule.18 The action of hydrogen in maintainingthe supply of active molecules in the unimolecular thermal decomposi-tion of acetaldehyde is such that no one activated state is favouredrather than another.l9 Experiments on the decomposition of diethylether at pressures up t o 200 atmospheres seem t o indicate that thenumber of degrees of freedom concerned in the mechanism of aunimolecular reaction may vary with the time between collisions.20The free acceptance and development of these conceptions hasbeen complicated by a view which has recently been advanced21that the decompositions by heat of the vapours of many organiccompounds are chain reactions involving the formation of freeradicals.The evidence for this is founded on the nature of theproducts of decomposition, on the kinetics,22 and on the removalof metallic mirrors.23 The thermal decomposition of dimethylether is accelerated by the introduction of methyl radicals from thephotodecomposition of acetone,,* and the methylene radical hasbeen recognised in the decomposition of diazomethane in presenceof ether.25 A little azomethane mixed with the vapour of acetalde-hyde a t 300" brings about an acceleration of the decomposition of16 See Ann. Reports, 1933, 30, 40.1' C. N. Hinshelwood, C. J. M. Fletcher, F. H. Verhoek, and C. A. Winkler,Proc. Roy. SOC., 1934, [ A ] , 146, 327; see also the case of N,O, E. Hunter,ibid., 144, 386; A., 603.l8 M. Polanyi, ibid., 146, 253.l9 C.J. M. Fletcher and C. N. Hinshslwood, Trans. Furaduy SOC., 1934,ao E. W. R. Steacie and E. Solomon, J . Chem. Physics, 1934, 2, 503; A.,21 F. 0. Rice, Trans. Faraday SOC., 1934, 30, 152; Ann. Reports, 1933, 30,22 F. 0. Rice and K. F. Herzfeld, J . Amer. Chenz. SOC., 1934, 56, 284; A.,23 F. 0. Rice and F. R. Whaley, ibid., p. 131 1 ; A., 863.84 J. A. Leermakers, ibid., p. 1899; A., 1184.Z 5 F. 0. Rice and A. L. Glasebrook, ibid., p. 2381.30, 614; A., 969.1179.48.36960 GENERAL AND PHYSICAL CHEMISTRY.the latter.26 This has been explained as the initiation of chainsby methyl radicals derived from the azomethane. It must beremembered, however, that the thermal decomposition of aldehydesis catalysed by many substances, particularly by molecules of highpolarisability such as iodine or hydrogen ~ulphide.~' The generalconclusion that long chains are set up in the decomposition oforganic molecules must be regarded as provisional (see p.48 foreffect of methyl radicals on acetone). The reactions do not showthe features commonly associated with chain reactions, such asinhibiting effects, wall effects, and complicated kinetics. There areother uncertainties of an experimental nature. Traces of oxygenmay profoundly modify the kinetics of the decomposition reactions.In the thermal decomposition of acetaldehyde, a little oxygenincreases the normal decomposition by as much as 1600 moleculesfor each oxygen molecule present .28An acceleration due to traces of oxygen is also observed inpolymerisation reactions, as in the case of eth~lene.~9 Until furtherwork is carried out, the detailed interpretations of the mechanismsof the decompositions of vapours of organic substances such asaliphatic hydrocarbon^,^^ ethers,31 alkyl nitrites,32 aldehydes,33tertiary alcohols,34 and possibly even of the polymerisations ofunsaturated hydrocarbons 35 must remain uncertain.Carefulreinvestigation of many of the above reactions with the specialpurpose of deciding the nature of the mechanism is urgently re-quired.26 D. V. Sickman and A. 0. Allen, J. Amer. Chem. Soc., 1934, 50, 1261,2031 ; A., 758.27 S. Bairstow and C. N. Hinshelwood, Proc. Roy. SOG., 1933, [A], 142, 77;A., 1933, 1251; H. Fromherz, 2. physikal. Chem., 1934, [B], 25, 301; A , , 737.28 Letort, Compt.rend., 1933,197, 1642; 1934,199, 351; A,, 1934, 38, 1073.29 H. H. Storch, J. Amr. Ohm. SOC., 1934,56, 374; A., 369.3o W. A. Bone, Trans. Paraday SOC., 1934, 80, 148; A. I. Dintzess, Compt.rend. Acad. Sci. U.R.S.S., 1933, 4, 153; A., 1934, 259; A. I. Dintzess andA. V. Frost, J. Gen. Chem. Russ., 1933, 3, 747; A., 1934, 151 ; R. E. Paul andL. F. Marck, Ind. Eng. Chem., 1934, 26, 454; A,, 603.a1 W. Ure and J. T. Young, J . Physical Chem., 1933, 37, 1169, 1183; A.,1934, 261; 0. K. Rice and D. V. Sickman, J . Amer. Ohern. SOC., 1934, 50,1444; A., 989.32 E. W. R. Steacie and G. T. Shaw, J. Chem. Physics, 1934,2,345; A , , 847.83 C. C. Coffin, Canadian J. Res., 1933,9,603; A., 1934,368; C. C. CoffinandA.L. Geddes, J. Chem. Physics, 1934, 2,47; A., 259; Canadian J . Res., 1934,11, 180; A., 1179; I;. S. Kassel, J. Chem. Physics, 1934, 2, 106; A., 368.34 R. F. Schultz and G. B. Kistiakowsky, J. Amer. Chem. SOC., 1934, 56,395; A., 369.35 W. E. Vaughen, ibid., 1933, 55, 4109; A., 1933, 1249; T. S. Chambersand G. B. Kistiakowsky, ibid., 1934, 50, 399; A., 369; M. V. Krauze, M. S.Nemtzov, and E. A. Soskina, Compt. rend. Acad. Sci. U.R.S.S., 1934, 3, 262;A., 1179BOWEN : CHEMICAL KINETICS. 61New measurements of the quantum efficiency of the photo-isomerisation of the o-nitrobenzaldehydes to o-nitrosobenzoic acidsshow that its value is about 0.5, both in the dissolved and in the solidstate, results which are in agreement with earlier work.36 From aconsideration of the structure and of the nature of the energysurfaces of the molecule, it is concluded that the reason for thisvalue is the approximate equality between the times of deactivationand reactivation.It may be that if the N-0 bond in the nitro-group next to the aldehyde group is excited, reaction almost alwaysoccurs, while if the further bond is excited, deactivation takes place.If this is so, a new field connecting stereochemistry and photo-chemistry may be opened up.In a molecule which has more than one light-absorbing centreit is possible by varying the wave-length to excite it at differentpoints. The photochemical reactions of such molecules are naturallyof great interest. An example of this is found in trans-~tilbene,~~which changes into the cis-form with a quantum efficiency of unitywhen irradiated with ultra-violet light of 3135 A.; the excitationbeing of the ethylene linkage, and probably changing the doublebond into something approaching a single bond, so permitting ofrotation.In the shorter ultra-violet region is another absorptionband, probably associated with excitation of the aromatic part ofthe molecule. The quantum efficiency of the change in light of thisregion is 0-4. How the excitation energy is transferred fromaromatic nucleus to ethylene linkage, whether by collision, internalrearrangement of energy within one molecule, or through fluorescence,is not known.Another problem of the greatest interest is that of “normal”and “ slow ” reactions in solution.It is now generally acceptedthat collisional frequencies between molecules in dilute solution ina liquid are not very different from those in a gas at the same con-centration.38 In the expression for the rate of a chemical reaction,vix., rate = PZe-E‘RT, where E = heat of activation, 2 = col-lisional number, and P = probability that reaction will occur ifthe energy exceeds E, many reactions have a value of P not far fromunity, and this is generally the case for reactions involving thesubstitution of a negative group by a negative ion, as in the reactionR,R,R,CCl+ OH’ j R,R2R,C*OH + Cl’. The rate of such38 P. A. Leighton and F. A. Lucy, J. C‘hem. Physics, 1934, 2, 756, 761;F. Weigert and L. Brodmann, Trans. Faraday SOC., 1926, 21, 453; A., 1925,ii, 1075; E.J. Bowen, (Sir) H. B. Hartley, W. D. Scott, and H. G. Watts, J.,1924, 125, 1218.87 A. Smakula, 2. physikal. Chem., 1934, [B], 25, 90; A., 611.88 E. A. Moelwyn-Hughes, Chem. Reviews, 1932, 10, 24152 GENERAL AND PHYSICAL CHEMISTRY.reactions is given approximately by the expression k ~ ~ ~ ~ . , ~ =101Oe-EIRT, the only variable being the value of the heat of activationE . M. Polanyi 39 has developed a simple pioture of the mechanismof these reactions which shows that optical inversion is always to beexpected, and that the heat of activation depends on the forceconstants within the molecule. The phenomena of the ‘( Waldeninversion ” and of ‘( stereo-hindrance ” are thus rendered moreintelligible.For certain other types of reactions in solution the probabilityfactor P is very low, sometimes reaching values ofSuch low efficiencies of reaction cannot be explained by thedeactivating influence of the solvent, but may arise from the necessityfor a certain orientation during collision, for a certain distributionwithin the molecules of the energy of activation, from an “ ionic ”mechanism, or from other C ~ U S ~ S .~ ~It is well known that the rates of bimolecular organic reactions aregreatly influenced by changes in the substituents in the reactingand an interesting study has been made on the reactionin benzene solution between substituted benzoyl chlorides and sub-stituted a n i l i n e ~ . ~ ~ It appears that the changes in the rates ofreaction due to changes in the substituents of the reacting moleculesare chiefly due to changes in the heats of activation of theand not to changes in the probability factor, which has the low valueof about 10-7.The effect of substituents in this reaction is thussimilar to that found by A. E. Bradfield and his co-workers45 forthe rates of chlorination of phenyl and tolyl ethers. These re-markable results were certainly unexpected, and show that in spiteof the number of hypothetical reasons for the “ slowness ” of thesereactions, all of which might be operating together, in certain re-actions an unforeseen simplicity emerges. Of the possibilitiesmentioned above, the factor which appears the most constant isthat of orientation, but it is premature to say that this is the chiefreason for the “ slowness ” of these reactions.Another aspect ofthe problem remains to be explored. These “ slow ” reactions arevery susceptible to solvent influence, and go much faster in solvents3s Proc. Roy. SOC., 1934, [B], 116, 202; Mem. Manchester Lit. Phil. SOC.,1934, 41, 41.40 See Ann. Reports, 1932, 29, 42; Hinshelwood, “ Kinetics of ChemicalChange in Gaseous Systems,” 3rd edn., Oxford, 1933, p. 230.4 1 Idem, J . , 1934, 1357; A., 1248.4% See Ann. Reports, 1933, 30, 42.43 E. G. Williams and C. N. Hinahelwood, J., 1934, 1079; A . , 971.44 See H. A. C. McKay, J . Soc. Chem. Ind., 1934, 53, 870.45 A. E. Bradfield, W. 0. Jones, and F. Spencer, J., 1931, 2907; A., 1932,to26; Clbem. and Ind., 1932, 254BOWEN : CHEMICAL KINETICS.53of high dipole moment. They are probably, in fact, not bimolecularbut termolecular, a collision with a solvent molecule being necessaryfor reaction. Such a necessity may arise if the wave functions ofthe original and the reacted forms of the bimolecular complex are ofdifferent symmetry ; transitions will then be possible only throughperturbations due to the electric field of solvent molecules in thenear neighbo~rhood.~~ There are experimental indications, butlittle more at present, that the effect of the solvent on " slow "reactions is to alter the probability factor P, as expected on theabove considerations.The process of esterification is a '( slow " reac-tion, and needs athird catalyst molecule. In ester formation between acetic acidand methyl alcohol, the probability factor P is lo-' when the catalystmolecule is another undissociated acetic acid molecule, but is lo4when the catalyst is the hydrogen ion.47 An investigation of theacetone-iodine reaction, which similarly needs a catalyst molecule,has shown that the probability factors for the reaction proceedingunder the influence of different catalysts vary considerably, and arerelated to the acid strength of the catalyst molecule.& From thisit appears that the polarisation, if not the ionisation, of the catalystmolecule is an essential condition for reaction, as expected from theabove wave-mechanical considerations.Niscelluneous Reactions.-The reaction between hydrogen andoxygen has been investigated under new conditions.In theSchumann region of the ultra-violet, oxygen molecules are dis-sociated into normal 3P and metastable 1D atoms, and the latterare found to react with hydrogen much more rapidly than theformer.49 To avoid the use of waxed-on fluorite plates for work inthis region, very thin (10 p) bubble-shaped windows of quartz wereused.w The mercury-sensitised reaction between hydrogen andoxygen, where the hydrogen i s dissociated, has been investigated bymeasuring the stationary atom concentration through the ortho-parahydrogen change.51 The reactions H + 0, --+ HO, (andH + CO --+ HCO) are thereby found to be three-body collisionalprocesses. There is little difference in rate between the mercury-sensitised reactions of hydrogen and deuterium with oxygen, where46 C .Zener, Proc. Roy. SOC., 1934, [A], 146, 254; J. E. Lennard-Jones,4 7 C. N. Hinshelwood and A. T. Williamson, Trans. Paraday Soc., 1934,48 G. F. Smith, J . , 1934, 1744.49 H. Neujmin and B. Popov, 2. physikal. Chem., 1934, [B], 27, 15.60 Cf. 2. Physik, 1932, 70, 322.5l L. Farkas and H. Sachsse, 2. physikal. Chem., 1934, [B], 27, 111.ibid., p. 242.30, 1145; A. C. Rolfe and C. N. Hinshelwood, ibid., p. 935; A., 118054 GENERAL AND PHYSICAL CEIEMISTRY.the process is an atomic The thermal chain reactions betweenthese substances have different rates at pressures above the upperexplosion limit, and have different upper limits.53 The quantitativeinterpretation of these effects affords a means of choosing betweendifferent possibilities of chain branching and ending.5PThe mechanism of the photodecomposition of gaseous ammonia,by light of wave-length about 2100 A.has been further investigatedby the use of the new forms of hydrogen. The primary processappears to be NH, + ~ L v 4 NH, ’+ H (through predissociation),but the low quantum efficiency (about 0.25) indicates some kindof back reaction.55 L. Farkas and P. Harteck 56 have measured thestationary hydrogen-atom concentration during illumination bymeans of the ortho-para hydrogen change. From the variation ofthis concentration with temperature, pressure, and light intensity,they conclude that the atoms largely combine with ammonia togive NH,, which can then re-form ammonia or decompose bysecondary reactions.If this is so, the complex NH, cannot havefour equivalent N-H linkages, Le., it must be N€13-H, since H. S.Taylor and J. C. Jungers 57 have shown that when gaseous ammoniais illuminated in presence of deuterium, the reaction NH, + D +NH,D + H does not readily take place. An equilibrium mixtureof the deuteroammonias, NH,D, NHD,, and ND,, recognisable bytheir different absorption spectra, is actually produced on illumina-tion of ammonia-deuterium mixtures, but through a mechanisminvolving the preliminary decomposition of the ammonia, followedby the reaction NH, + D, -+ deuteroammonias. Further quanti-tative examination of the problem by the newer technique is stillrequired.The mercury-sensitised photodecompositions of ammonia and oftrideuteroammonia have been that of the latter beingmore than ten times slower than the former.Although it is notyet possible to explain the mechanism in detail, the results alreadyshow that the quenching of the excited mercury atom by the52 M. G. Evans, J . Chem. Physics, 1934, 2, 726; E. W. Melville, Nature,53 C. N. Hinshelwood, A. T. Williamson, and J. H. Wolfenden, ibid., p. 836;54 See C. N. Hinshelwood and A. T. Williamson, “ The Reaction between65 R. A. Ogg, P. A. Leighton, and F. W. Bergstrom, J . Amer. Chem. SOC.,s6 2. physikal. Chem., 1934, [B], 25, 257; A,, 739.57 J . Chem. Physics, 1934, 2, 452.6 8 J. C. Jungers and H. S. Taylor, ibid., p. 373; A., 1078; M. G. Evans and1934, 133, 947.A., 736.Hydrogen and Oxygen,” Oxford, 1934.1934, 56, 318; A., 374.H.S. Taylor, ibid., p. 732BOWEN : CHEMICAL KINETICS. 55ammonia molecule only rarely leads to photosensitised decomposition,i.e., most of the ,PI mercury atoms prtss to the ,Po state, transferringan energy inadequate to decompose the ammonia molecule. Thequenching ratio of NH, : ND, is 4 : 1.Recent work on the photochemical reactions between chlorineand hydrogen, carbon monoxide, or methane has been directedtowards a more quantitative knowledge of the mechanisms of chainpropagation and ending.60 The chain carrier is probably C1, ratherthan C1.61 The kinetics of the hydrogen-chlorine reaction inpresence of a large excess of oxygen show that the chain-endingprocess is H + 0, + H0,.62 The first step, C1 + H, --+ HC1 +H, does not occur on every collision, but needs activation energy,and owing to the difference in zero-point energies of the two isotopesof hydrogen, the molecule D, reacts at ordinary temperature onlyone-third as rapidly as the molecule H,.63 A similar difference inrate, for the same reason, is found in the thermal reactions ofbromine with hydrogen or deuterium.64Investigations have been made of the photokinetics of a numberof reactions whose rate is proportional to the square root of thelight intensity : the photohalogenation of dinnamic acid,65 thereaction in the gas phase between chlorine and trichlorobromo-methane,66 and the reaction between chlorine and chlor~forrn.~~ Thephotobromination of acetylene is a very sensitive chain reaction. 68Reference may also be made to the following photoreactions whichhave recently been examined : the decomposition of solid lithiumhydride,G9 the oxidation of mercury v a p o ~ r , ~ ~ the photolysis of5s L.T. Jones and J. R. Bates, J. Amer. Chem. SOC., 1934, 56, 2282.6o See Ann. Reports, 1933, SO, 49.61 G. K. Rollefson, J. Amer. Chem. SOC., 1934, 56, 674; A., 496.e2 K. B. Krauskopf and G. K. Rollefson, ibid., p. 327; A., 374; see alsothe effect of oxygen on the thermal hydrogen-chlorine reaction, R. N. Pease,ibid., p. 2388.63 L. Farkas and A. Farkas, Naturwbs., 1934, 22, 218; A., 602; G. K.Rollefson, J. Chem. Physics, 1934, 2, 144; A., 610.64 F. Bach, K. F. Bonhoeffer, and E. A. Moelwyn-Hughes, 2. physikal.Chem., 1934, [B], 27, 71.66 A.Berthoud and D. Porret, Helv. Chim. Acta, 1934, 17, 237; A., 496;W. H. Bauer and F. Daniels, J. Amer. Chem. SOC., 1934, 56, 378; A., 374.66 H. G. Vesper and G. K. Rollefson, ibid., p. 1455; A., 976.6 7 H. J. Schumacher and K. Wolff, 2. physikal. Chem., 1934, [B], %,161; A., 740; cf. A. T. Chapman, J . Amer. Chem. ~Soc., 1934, 56, 818.;A . , 611.J. E. Booker and G. K. Rollefson, ibid., p. 2288.69 F. Bach and K. F. Bonhoeffer, 2. physikal. Chm., 1933, [B], 23, 266;70 J. M. Frank, C m p t . rend. Acad. Sci. U.R.S.S., 1933, 4, 146; A., 1934,A., 1934, 7.26356 GENERAL AND PHYSICAL CHEMISTRY.silver halides,'l of metallic carbonyls,72 of the oxides of nitrogen, 73of chlorine dioxide,74 of ozone,75 of mixtures of chlorine and ozone,76of liquid ethyl iodide,77 of the photo-oxidation of ethyl iodide,78and of the effect of inhibitors on the decomposition of hydrogenperoxide.79The technique of actinometry in the ultra-violet has now beendeveloped so as to be the most convenient metlhod of measuringradiation for photochemical purposes. 8oA new method of measuring very high-velocity gas reactions 81consists in introducing n atoms per second of a gas such as sodiumvapour into the reacting gas such as a methyl halide at a con-centration c, and measuring by light -absorption methods the numberN of atoms of sodium in the stationary reaction zone (i.e., the flame).The velocity constant is then simply nc/N. This method is morereliable than earlier ones for measuring the fastest reactions.Ast'reaming method has been applied t o investigate the very rapidreaction between sulphur trioxide and water in the vapour phase.82The Hartridge-Roughton method of measuring fast reactions hasbeen applied to an extensive investigation of the reactivity ofhzmoglobin towards oxygen and carbon m0noxide.8~ The chainmechanisms of the autoxidations of solutions of sulphites and ofaldehydes have been discussed in the light of recent Thethermal decomposition of fluorine monoxide provides an exampleof a reaction in which the life of the activated molecule is so shortthat practically every activated molecule decomposes under ordinary71 P. Feldman and A. Stern, 2. physikal. Chem., 1934, [B], 26, 45;A., 976.72 H. W. Thompson and A.P. Garratt, J . , 1934, 524, 1817; A., 582;A. Terenin, J . Chm. Physics, 1934, 2, 441 ; A., 940.73 H. H. Holmes and F. Daniels, J . Amer. Chem. SOC., 1934, 56, 630; A.,496.74 J. W. T. Spinh and J. M. Porter, ibid., p. 264; A., 374.76 L. J. Heidt and G. S. Forbes, ibid., p. 2365.7 6 A. C. Byrns and G. K. Rollefson, ibid., p. 2245.7 7 B. M. Norton, ibid., p. 2294.7 8 L. T. Jones and J. R. Bates, ibid., p. 2285.79 D. Richter, J., 1934, 1219; A., 1075.8o F. P. Brackett and G. S. Forbes, J . Amer. Chem. SOC., 1933, 55, 4459;A., 1934, 40; G. S. Forbes and L. J. Heidt, ibid., p. 2363; L. Farkas, 2.physikal. Chem., 1933, [B], 23, 89; A., 1933, 1255.81 L. Frommer and M. Polanyi, Trans. Paraday SOC., 1934, 30, 519; A.,969.s2 C. F. Goodeve, A.S. Eastman, and A. Dooley, ibid., p. 1127.83 F. J. W. Roughton, Proc. Roy. SOC., 1934, [BJ, 115, 451; A., 1073;see also ibid., 116, 192, 198.84 H. L. J. Biickstrom, 2. physikal. Chem., 1934, [B], 25, 99, 122; A., 611;see also G. E. K. Branch, H. J. Almquist, and E. C . Goldsworthy, J . Amr.Chem. Soc., 1933, 55, 4052; A., 1252BOWEN : CHEMICAL KINETICS. 57conditions of pressure.85 A further examination of the reactionbetween hydrogen and sulphur vapour has led to results in dis-agreement with earlier work.86 The mechanism of combination ofhydrogen atoms in the gaseous phase is through triple collisions,and interesting results have been obtained on the efficiency of theprocess.87 In the homogeneous thermal decomposition of carbonsuboxide, C,O,, a t 200°, dicarbon gas, C,, is supposed to be formedas a carmine-red vapour which rapidly polymerises to a purple-redsolid variety of carbon.88An extremely interesting use has been made of the isotope ofoxygen 0ls to decide whether 6he bond between oxygen and alkylor acyl is split in the hydrolysis of esters by alkali.89 Amy1 acetatewas hydrolysed by alkali in water containing more than the usualamount of 0l8, and the question whether the 0l8 goes to the acidor the alcohol was investigated, the result showing that the acyl-oxygen bond is the one which breaks.The experiments also show,incidentally, that no interchange takes place between hydroxylions and the hydroxyl group of the alcohol; Le., alcohols which areknown to ionise giving hydrogen ions do not appreciably ionise inanother way giving hydroxyl ions.The hydrogen isotope has beenused to investigate the mechanism of interchange of hydrogen atomsbetween hydrocarbons and hydrogen in presence of metallic catalysts,Le., to throw light on the actual mechanism of processes of hydro-genati0n.mThe method of investigation of films by means of their surfacepotentials has been applied by E. K. Rideal and his co-workers t othe measurement of reaction velocities in unimolecular films.The molecular statistics of the hydrolysis of a film of stearolactoneby hydroxyl ions closely resemble those for similar reactions inhomogeneous solution.91 Vitamin-D appears to be formed onirradiation of films of ergosteroLg2 The rate of oxidation of unimole-cular films of unsaturated acids by dilute solutions of permanganatedepends on the degree of extension of the filmy the rate diminishingwhen the unsaturated linkings are removed from the surface bycornpres~ion.~~ Experiments of great interest in biochemistry havebeen carried out on the rates of digestion of monolayers of proteins85 W.Koblitz and H. J. Schumacher, 2. physikal. Chem., 1934, [B], 25,283; A., 736.86 E. E. Aynsley and P. L. Robinson, Nature, 1934, 133, 723; A . , 737.87 H. M. Smallwood, J . Amer. Chem. Soc., 1934, 56, 1542; A., 969.8 8 A. Klemenc, 2. Elektrochern., 1934, 40, 488; A,, 969.89 M. Polanyi and A. L. Szabo, Trans. Paraday SOC., 1934, 30, 508.90 IurB Horiuti and M. Polanyi, ibid., p. 1164.9 1 R.J. Fosbindor and E. K. Rideal, Proc. Roy. SOC., 1933, [A], 143, 61.92 R. J. Fosbinder, ibid., 139, 93; A., 1933, 326.93 A. 13. Hughes and E. K. Rideal, &id., 140, 253; A., 1933, 67958 GENERAL AND PHYSICAL CHEMISTRY.by enzymes.94 In certain cases the rate of attack of enzymes onprotein films is inhibited by compression of the film, an observationwhich seems paralleled by the behaviour of the metabolism of restingmuscle, which rises when the muscle is maintained in a stretchedc0ndition.~5 E. J, B.6. ELECTROLYTES.Theoretical interest in this field still centres mainly on the ap-plicability of a simplified electrostatic model to account for theproperties of ionic solutions, and the chief features to report arethe application of this model to a larger number of problems, theaccumulation of a considerable amount of accurate data for verydilute solutions, and attempts to extend the theory to more concen-trated solutions.The thermodynamic properties of an ionic solution can all bedescribed in terms of the free energy, and the electrostatic theorygives as the limiting law in dilute solutionsF, = - (~Niz,2)3'22~32/;;/3D3'2Z/~~V .. (1)zwhere Fe is the electrical contribution to the free energy of a solutionof dielectric constant B containing Ni ions of charge X*E in volume V .This expression is equivalent to the limiting law for activity co-efficients (or osmotic coefficients) which was discussed in theseReports last year.l Mention may, however, be made of a series ofaccurate freezing-point measurements for 25 uni-univalent saltsin aqueous solution.2 Treatment of these data by the method ofleast squares (to avoid errors of personal judgment or prejudice)shows that the limiting slope certainly does not differ from thetheoretical value by more than The same conclusion isreached by J.Lange4 from his cryoscopic measurements on tetra-alkylammonium halides.Differentiation of equation (1) with respect to temperature orpressure leads to expressions for other properties of the solutionwhich may be used to test the theory and are actually found to bemuch more sensitive to deviations than the activity coefficients.13' J. H. Schulman and E. K. Rideal, Biochem. J., 1933,27, 1551; A., 1933,1331.O 6 See E. I(. Rideal, Proc.Roy. Soc., 1934, [B], 116, 200.Ann. Repmts, 1933, 80, 21.G. Scatchard, S. S. Prentiss, and P. T. Jones, J . Amm. Ohm. SOC., 1932,54, 2690; A., 1932, 912; ibid., 1934, 56, 805; A . , 696; Scatchard andPrentiss, ibid., 1932, 54, 2696; A., 1932, 912; ibid., 1933, 55, 4355; A., 1934,25; ibid., 1934,56, 807; A., 596.S. S. Prentiss and G. Scatchard, Chem. Reviews, 1933, 13, 139.2. physikal. Chem., 1934, [A], 168, 147; A . , 59659 BELL : ELEC'l'ROLYTES.One differentiation with respect to T gives the heat of dilution ; thissubject has been recently discussed in these reports,6 since when nofundamental advances have been made. One differentiation withrespect to pressure gives an expression for the variation of the partialmolal volume of the electrolyte with concentration, first derivedtheoretically by 0.Redlich and P. Rosenfeldt.6 The theory predictsthat in dilute solutions the partial molal volume should be a linearfunction of &, and that the slope of this line should depend only onthe properties of the solvent and the valency type of the electrolyte.It is difficult to carry out density measurements a t sufficientlygreat dilutions for a satisfactory test, but work by W. Geffcken andD. Price on uni-uni- and uni-bi-valent salts in water gives resultswhich tend to approach the theoretical line at high dilutions, Theapplication of the theory to other solvents is rendered difficult byuncertainty as to the value of the pressure coefficient aD/aP, butthe results of Butler for methyl-alcoholic solutions are at leastcompatible with the theory.A still unexplained and striking factis that the results for high concentrations (0-1-3N) conformaccurahely to a square-root law, but with a different slope for eachsalt.Two differentiations of equation (1) with respect to T give thespecific heat of the electrolyte sol~tion,~ two differentiations withrespect to P its compressibility,1° and successive differentiationswith respect to T and P its thermal expansibility.ll (In each casewe obtain the variation of the corresponding partial molal quantitywith the concentration.) The expressions thus obtained involvethe coefficients a2DlaT2, a2D/aP2, and a2D1aTaP, which are not atpresent known with any certainty, and it is thus impossible to makea complete quantitative test. However, in each case the theorypredicts a linear variation with l/c, with a slope proportional to thevalency factor (CviQ)3/2, and otherwise depending only on theAnn.Reports, 1932, 29, 29-34.See ibid., 1930, 27, 29. ' 2. physikal. Chem., 1934, [B], 26, 81; A., 959.W. C. Vosburgh, (Miss) L. C. Connell, and J. A. V. Butler, J., 1933, 933.8 See V. K. LaMer and I. A. Cowperthwaite, J . Amr. Chm. SOC., 1933,55, 1004; A., 1933, 466; H. Hammerschmidt and E. Lange, 2. physikal.Chem., 1032, [ A ] , 160, 445; A., 1932, 913. It should be noted that in thiscase the omission of the terms involving &/aT and aS/aT2 (as in the expressiongiven by W. Lange and G. Messner,Z. Ekktrochem., 1927, 33, 440; A,, 1928,134; and by M.Randall and F. D. Rossini, J . Arner. Chem. SOC., 1929, 61,323: A., 1929, 398) introduces a much greater error than in the case of theheat of dilution (cf. Ann. Reports, 1932, 29, 30, footnote), the error in waterbeing about 16%.10 F. T. Gucker, Chem. Reviews, 1933, 13, 111.11 Idem, J . Amer. Chem. Soc., 1934, 66, 1017; A., 729GO GENERAL AND PHYSICAL CHEMISTRY.properties of the solvent. Some experimental work has been donerecently on the determination of the specific heats,12 com-pressibi1ities,l3 and thermal expansion l4 of electrolyte solutions,and F. T. Gucker lo has reviewed the available data. Although thesolutions were, in general, much too concentrated for the simpleDebye-Huckel picture to apply, a square-root relation was foundto hold in all cases, but with individual slopes for the differentelectrolytes.These slopes are of the predicted order of magnitude,and change with the valency type roughly as predicted by the theory,but the experimental points show no signs of approaching a commonslope for all electrolytes of the same type. It may be a significantfact that if the solutes are arranged in order of increasing slope ofthe @-&-curve, the slopes for the other properties follow almost thesame order, indicating the presence of some factor not accountedfor by the electrostatic theory which affects all the properties in thesame way. It is, however, disconcerting to find that the partialmolal volumes and compressibilities of urea and sucrose in aqueoussolution also exhibit a linear dependence on d< since if this relationis general for non-electrolyte solutions it is obviously unjustifiablet o attribute the behaviour of electrolytes primarily to the ionicatmosphere.The fundamental conceptions of the ionic atmosphere continueto be supported by work on non-stationary phenomena (conductivity,viscosity, and dispersion effects).L. Onsager and R. M. Fuoss l5have given a general theoretical treatment of such irreversibleprocesses which applies to the conductivity, viscosity, and diffusionof an arbitrary mixture of strong electrolytes. Since the lastreport on the conductivity of electrolytes l6 very accurate work hasbeen done on aqueous solutions by T. Shedlovsky and his col-l a b o r a t o r ~ .~ ~ By means of an improved technique, it is now possible12 T. W. Richards and M. Dolo, J . Amer. Chem. SOC., 1929, 51, 794; A.,1929, 652; M. Randall and F. D. Rossini, ibid., p. 323; A., 1929, 398; F. T.Gucker and K. H. Schminke, ibid., 1932,54, 1358; 1933,55, 1013; A., 1932,696; 1934, 466.13 E. P. Perman and W. D. Urry, Proc. Roy. SOC., 1929, [A], 126, 44; A.,1930, 154; ibid., 1934, [A], 146, 640; A., 1304. F. T. Gucker, J . Amer.Chem. SOC., 1933, 55, 2709; A., 1933, 901; A. F. Scott, V. M. Obenaus, randR. W. Wilson, J . Physical Chem., 1934, 38, 931, 951.l4 F. T. Gucker, J . Amer. Chem. SOC., 1934, 66, 1017; A., 729.l5 J . Physical Chem., 1932, 36, 2689; A , , 1933, 28.16 Ann. Reports, 1930, 27, 326.l7 T. Shedlovsky, J . Arner. Chem.SOC., 1932, 54, 1405; A., 1932, 699;T. Shedlovsky and A. S. Brown, ibid., 1934, 56, 1066; A., 735. Cf. alsoG. Jones and C. F. Bickford, ibid., p. 602; A., 491; J. Lange, 2. phy8ikaZ.Chem., 1934,108,147 ; A., 596 ; Shedlovsky, A. S. Brown, and D. A. McInnes,Trans. Amer. Electrochem. SOC., 1934, 66, 237; A., 1308.More experimental work is neededto measureaccuracy of0.001N thewithin thisnoted thatSerpinski,lsBELL : ELECTROLYTES. 61the conductivity of 0.00003N-salt solutions with an0-0270, and it is satisfactory to find that up to aboutexperimental results agree with the Onsager equationsmall experimental error. In particular, it may beV. K. Sementschenko, B. V. Jerofejev, and V. V.using the same technique, have found that magnesiumsulphate agrees with the theory at sufficiently great dilutions.Older measurements on bi-bivalent salts at somewhat higher concen-trations gave slopes about lO0yo higher than the theoretical, butit now appears certain that in all such cases the apparent straightline obtained is actually the middle section of a curve having apoint of inflexion.Shedlovsky has also proposed an empiricalextension of the Onsager equation : if the latter (for a uni-univalentelectrolyte) is written in the formA = A , - (ah, +2p)dC . . . (2)then Shedlovsky's equation isA, = (A + 2p&)/(l - a&) - BC . . . (3)B being an empirical constant. If B is zero, it reduces to equation(2). This equation represents the experimental data better thanany other equation with one empirical constant, and agrees withdata for uni-univalent electrolytes up to nearly 0.1N.No theoreticalbasis for the equation has yet been found, but it may be significantthat the value of B is always within 15% of (do + 2p).Improved technique in the measurement of transport numbers bythe moving-boundary method has raised the accuracy to about0.02% in dilute solutions.1s On the basis of equation (2) it is easilyshown20 that in dilute solutions the variation of the transportnumber of the anion (T,) with concentration is given by. . . . (4)T+O being the value of the transport number at infinite dilution.This limiting relation agrees well with the experimental results,except for nitrates, which are known to be abnormal in severalrespects.By combining the results of conductivity and transpart-number measurements, it is possible to obtain accurate values forthe single ionic mobilities a t different concentrations.21 It is found18 2. physikal. Chem., 1934, 16'7, 188; A., 257.18 For description of technique and full references, see D. A. McInnes and20 L. G. Longsworth, J . Amer. CJwm. SOC., 1932, 64, 2741; A., 1932, 914.2 1 D. A. McInnes, T. Shedlovsky, and L. G. Longsworth, ibid., p. 2758;L. G. Longsworth, Chem. Reviews, 1932, 11, 171.A,, 1932, 91462 GENERAL AND PHYSICAL CHEMISTRY.that Kohlrausch's law of independent ionic mobilities is valid upto about O-OlN, nitrates again being an exception.The theory of the viscosity of strong electrolytes22 has beenfurther treated by H.Palkenhagen and E. Vernon23 and the ex-perimental technique improved by the electric timing device of G.Jones and S. K. Talley 24 and the differential method of W. M. Coxand J. H. W~lfenden.~~ If the viscosity is expressed in the formq = q 0 ( l + A & + B c ) . . . . . ( 5 )qo being the viscosity of the pure solvent, then the value of A ispredicted by the Falkenhagen-Dole theory. There is reasonableagreement between the experimental and the theoretical values 26except for magnesium sulphate ; this probably corresponds to theearlier discrepancies found for the conductivities of bi-bivalentelectrolytes, and it may be anticipated that at still lower concentra-tions the theoretical relation will be obeyed. Agreement is alsofound for tetraethylammonium picrate in nitrobenzene, sodiumiodide in ethyl alcohol, and lithium chloride in acet0ne.~7 Cox andWolfenden have pointed out that the empirical constant B in equation( 5 ) is made up additively of quantities characteristic of the anion andcation, which relation was further confirmed (with some exceptions)by V.D. Laurence and J. H. Wolfenden.28 Jones and Talley haveshown that A is zero for a non-electrolyte, as would be expectedin the absence of ionic-atmosphere effects.The theory of the dispersion of conductivity and dielectric con-stant29 has been extended by H. Palkenhagen and W. Piachery3Owhile special points in the theory have been treated by M. Wien 31and P. D e b ~ e . ~ ~The experimental work on high-frequency conductivities has beenextended by the use of methods involving a measurement of theheat developed, and the theory is in general confirmed.33 The22 Cf.Ann. Reports, 1931, 28, 33.23 Phil. Mag., 1932, [vii], 14, 537; A., 1932, 1200.25 Proc. Roy. SOC., 1934, [A], 145, 475; A., 959.2e See refs. (24) and (25) ; also H. M. Glass and W. M. Madgin, J . , 1934,1124,27 Cox and Wolfenden, loc. cit.; G. R . Hood and L. P. Hohlfelder, J .Physical Chem., 1934, 30, 978.28 J., 1934, 1144; A., 1068.29 Cf. Ann. Reports, 1930, 27, 333.3O Physikal. Z., 1932, 33, 941; 1933, 34, 593; A., 1933, 8, 908; 2. Elektro-chern., 1933, 39, 617; A,, 1933, 908.31 Physikal. Z., 1933, 34, 625; A., 1933, 1016.32 Z . Elektrochem., 1933, 39, 478; A., 1933, 908.33 See, e.g., A.Deubner, Physikal. Z., 1932, 33, 223; A., 1932, 342; M.Wien, Ann. Physik, 1931, [v], 11, 429; A., 1931, 1370; 0. Neeae, aid., 1931,[v), 8, 929; A., 1931, 801; J. Malsch, Physikal. Z., 1932, 33, 19; A., 1932,214; Ann. Phy8ik, 1932, [v], 12, 865; A., 1932, 470.J . Amer. Chem. SOC., 1933, 55, 624; A,, 1933, 347BELL : ELEUTROLYTBS. 63available data for the dielectric constant of electrolytes a t highfrequencies also agree reasonably with the theory.34 It should,however, be noted that the majority of the above methods are onlycomparative, and give the difference between the dispersion effectsfor a standard uni-univalent electrolyte and the higher valency-typeelectrolyte being investigated. It is therefore disturbing to findthat some direct measurements of the high-frequency conductivityand dielectric constant of uni-univalent electrolytes give resultsnot agreeing with the theory.35 In many cases the interpretationof the results is complicated by dipole absorption by the solvent.36Improvements have also been made in the experimental measure-ment of conductivities at high field strengths.37 To avoid unduedevelopment of heat, such experiments have to be carried out withdischarges of very short duration, so that there is a kind of dispersioneffect superimposed upon the field effect, which appears experimen-tally as a variation of conductivity with duration of discharge.38A theoretical treatment of this phenomenon has been given by H.Falke~&agen.~~Since the equivalent conductivity in very high fields approachesthe value it has at infinite dilution,m it has been suggested that suchexperiments might be used to determine the true ionic concentrationof electrolyte solutions. Matters are, however, complicated by thediscovery that weak electrolytes give an abnormally great increaseof conductivity at high field strengths.41 This can only be attributedto an actual increase in the number of ions present, i.e., a displace-ment of the dissociation equilibrium by the tendency of the field tosplit up the undissociated molecules.This effect has been termedthe dissociation field effect, and has been treated theoretically byL. Onsager,e2 who obtains the equationwhere K , is the dissociation constant in a field E, and the ions havecharges el and e2 and mobilities Zl and I,.Both the nature and34 M. Wien and 0. Neese, loc. cit., ref. (33); W. Orthmann, Ann. Physik,1031, [v], 9, 537; A., 1931, 786; E. Plotze, ibid., 1933, [v], 18, 288; A , ,1933, 1243; H. Geest, Physikal. Z., 1933, 34, 660; A , , 1933, 1015.35 M. Jezewski and J. Kamecki, ibicE., pp. 88, 561; A., 1933, 250, 901;E. Glowatski, Ann. Physik, 1933, [v], 18, 217; A., 1933, 1120.36 B. G. Whitmore, Physikal. Z., 1933, 34, 640; A., 1933, 1015.37 M. Wien, ibid., 1931, 32, 545; A., 1931, 1012; F. Bauer, Ann. Physik,88 See M. Wien, loc. cit., ref. (37).39 Physikal. Z., 1931, 32, 353; A., 1931, 686.40 Cf. Ann. Reports, 1930, 21, 334.4 1 M. Wien, loc. cit., ref. (37); J. Schiele, Ann. Physik, 1932, [v], 7, 811 ;42 J .Chem. Physics, 1934, 2, 599; A., 1176.1930, [v], 6, 253; A,, 1930, 1254; W. Fucks, ibid., 12, 306; A., 1932, 231.A . , 1932, 813; Physikal. Z., 1933, 34, 60; A., 1933, 23164 GENERAL AND PHYSICAL CHEMISTRY.the observed order of magnitude of this effect agree with thisexpression.L. Onsager and N. N. T. Samaras 43 have also extended the numberof applications of the electrostatic picture by deducing an expressionfor the surface tension of dilute electrolyte solutions. They obtaina limiting law of the formd = a,+Aclog (B/c) . . . . (7)where A and B are constants depending only on the valency typeof the salt and the nature of the solvent. The available experi-mental data44 are not sufficiently accurate to test this relationstrictly, but the change of surface tension is roughly the same forall uni-univalent salts, and the results are not incompatible withequation (6).We have so far dealt only with the limiting laws for conductivity,etc., which are theoretically valid only at infinite dilution.Otherfactors must be introduced to account for the behaviour of aqueoussolutions of higher concentrations, and in non-aqueous solutionsit is rarely possible to reach dilutions a t which the limiting laws areobeyed.45 There are, in principle, two possible lines of approachin treating more concentrated solutions; one is to obtain a moreaccurate mathematical treatment of the electrostatic model, andthe other to allow for the existence of undissociated molecules insolution.The principles involved in these two methods of treat-ment have been recently dealt with ; 46 in the case of non-stationaryphenomena, however, the second alternative provides the onlypossibility of quantitative treatment, since it has so far only beenpossible to obtain the first approximation (corresponding to thelimiting law) in solving the differential equations involved. 0.Redlich 47 has obtained an equation for conductivity correspondingto the second approximation of Debye and Huckel for activitycoefficients, and finds agreement up to 0.1N for the alkali halides,but unfortunately his treatment refers to the incorrect equationsof Debye and Huckel, which do not take into account the Brownianmovement. It is probable, however, that an analogous treatmentof the correct Onsager equations would lead qualitatively to similarCf.also C. Wagner, Physikal. Z., 1924,25, 474; A,, 1925, ii, 387.J . Chem. Physics, 1934, 2, 528.44 See, e.g., A. Schwenker, Ann. Physik, 1931, 11, 525; A., 1931, 366.46 I n this connexion, it may be noted that J. E. Coates and E. G. Taylor(Nature, 1934, 134, 141; A , , 967) have found that the Onsager equation isobeyed by a number of salts in liquid hydrogen cyanide (dielectric constantabout 95) over the concentration range 0~00014~005N.46 Ann. Reports, 1932, 29, 21; 1933, 30, 22.4 7 Physikal. Z., 1925, 26, 199; 1926, 27, 528; A., 1926, ii, 541; 1926, 910BELL : ELECTROLYTES. 65results, i.e., to a conductivity curve lying above the limiting straightline.In many cases the deviation is actually in the oppositedirection, and although it is possible that higher degrees of approxi-mation would reproduce this feature (as in the case of activitycoefficient^),^^ the only quantitative treatment possible a t presentis to attribute all deviations from equation (2) to incomplete dis-sociation. Methods hitherto employed for the quantitative treat -ment of conductivity data have made use of the limiting law forthe activity coefficients of the ions, and have assumed a valuefor A,. have recently devised avaluable method of computation (employing the second approxima-tion of Debye and Hiickel for the activity coefficients) in whichboth A. and the degree of dissociation are derived from the experi-mental data, by a series of successive approximations.They haveapplied this method with success to a number of widely differingexamples, the dielectric constants varying from 2 to 80, and thevalues of the dissociation constant from 0-17 to 0.00007. Thesame authors 51 have accounted quantitatively for the appearanceof minima in solvents of low dielectric constant by assuming theformation of ion triplets capable of carrying current, which arein equilibrium with ions and neutral molecules. 51 The theoryagrees well with the results for tetraisoamylammonium nitratein dioxan-water mixtures with dielectric constants lower than 10. 62The nature of the forces involved in the formation of the undis-sociated molecules still remains a fairly open question.If theseare purely electrostatic (as in Bjerrum’s conception of ionicassociation), the dissociation constants obtained should be a uniquefunction of the dielectric constant of the solvent and a, parametera representing the distance of closest approach of the ions. This isfound to be the case for the same solutions, where the variation ofdissociation constant with dielectric constant can be accountedfor quantitatively by assuming a reasonable constant value for ~2.~3The formation of triple ions can also be treated by assuming onlyelectrostatic forces to be operative, and the expressions obtainedagree fairly well with the conductivity minima observed for salts indioxan-water mixtures and in benzene.52 It is interesting t o noteThe development of such “higherR.M. Fuoss and C. A.48 See Ann. Reports, 1932, 29, 24.49 J . Amer. Ci~em. Soc., 1933, 55, 476; A., 1933, 353.60 The ionic radius occurring in this expression was calculated from the61 Ibid., p. 2387;- A,, 1933, 785.6s Idem, ibid., p. 26.53 Idem, ibid., p. 1019; A,, 1933, 464.term8 ” is in any case open to theoretical criticism ; me &id., 1933, 30, 22.mobilities by applying Stokes’s law.A refinement of Bjerrurn’s treat-ment has been given by FUOM, Trune. Furaday SOC., 1934,30, 967; A., 1173.REP.-VQL. XXXI. 66 GENERAL AND PHYSICAL CHEMISTRY.that the theory approximately reproduces the relation =const. x 0 3 (where Q ~ . is the concentration corresponding to theminimum in the conductivity curve), previously advanced empiricallyby Walden.However, this simple picture is only valid in a verylimited number of cases, and, on account of solvation, the degreeof dissociation of an electrolyte depends, in general, not only on thedielectric constant of the solvent, but also on its chemical type.Moreover, in the case of many electrolytes (e.g., weak acids and basesand certain salts such as those of thallium and lead), the formationof an undissociated molecule involves specific chemical forces.These factors were dealt with in a recent reportYM and we need onlypoint out here that recent work in a number of widely differingsolvents continues to emphasise the diversity of electrochemicalbehaviour, e.g., in acetone, methyl ethyl ketone,55 acetophenone,cycZohexanone,56 c yanoacetic ester, o-cyanotoluene, 57 aniline,anhydrous hydra~ine,~~ nitromethane,60 nitrobenzene,61 liquidammonia,62 and metallic a l k y l ~ .~ ~ H. Ulich 64 has published adiscussion of the extreme types of physical and chemical interactionencountered. It is interesting to note that a suitable type of solventmay cause ionisation with solutes usually considered to be non-electrolytes, e.g. , iodine and cyanogen iodide give conducting solu-tions in pyridine and ketones, both I+ and I- being apparentlyformed,65 while aromatic nitro-compounds in anhydrous hydrazineare said to ionise according to the scheme &NO, + N,H4&NO2+ + N,H,-, only an electron transfer being involved.66It would be very valuable to have some independent evidenceof the degree of solvation and association and the nature of the forcesinvolved in these processes, especially in more concentrated soh-tions where the above methods of treatment lose their validity.ti4 Ann. Reports, 1930, 2'4, 326.66 P.Walden and E. J. Birr, 2. physikal. Chem., 1931, 153, 1; A., 1931,s6 Idem, ibid., 1933, 165, 26, 32; A., 1933, 784.5 7 J. C. Philip and P. Rangarsmanujam, J., 1932, 1512; A., 1932, 699.58 P. Walden and L. F. Audrieth, 2. physikal. Chem., 1933, 165, 11; A , ,ss P. Wdden and H. Hilgert, ibid., p. 907; A,, 1933.6o Walden and Birr, ibid., 162, 263 ; A., 1933, 467.61 W. F. K. Wynne-Jones, J., 1931, 795; A., 1931, 686. See also ref. (60).62 C. A. Kraus and W. W. Hawes, J . Amer. Chem. SOC., 1933, 55, 2776;e9 F.Hein and H. Pauling, 2. physikal. Chern., 1933, 165, 38; A., 1933,64 Ibid., p. 483; A., 1933, 908.6s L. F. Audrieth and E. J. Birr, J . dmer. Chern. SOC., 1933, 55, 668; A,,1933, 354; E. J. Birr, 2. physikal. Chem., 1933,165, 311; A., 1933, 907.66 P. Walden, 2. physikal. Chem., 1934,168, 419; A., 845.434.1933, 784.A., 1933, 907.907; 2. Elektrochem., 1933, 39, 537; A., 1933, 90767 BELL: KINETIU SALT EFFECTS.Such evidence is, however, still very rneagre,e7 although interest-ing work has recently been done by H. Fromherz and hiscollaborators 68 on the ultra-violet absorption spectra of aqueoussolutions of metallic halides. They find that for the alkali andalkaline-earth halides the changes of absorption spectra with con-centration are of the type expected for a purely electrostaticassociation, while for the halides of lead and thallium frequenciesappear corresponding to a much more permanent and intimatecombination.It has been pointed out by P.Debye 69 that, although the massesof the ions play no part in determining most of the properties ofionic solutions, they are of importance in the propagation of asupersonic wave through an electrolyte. By measuring the differencesin potential set up, Debye proposes to measure the masses of theions, so that the method may prove valuable in obtaining informationabout solvation. It should be noted that the recent extension ofmeasurements with the ultra-centrifuge to inorganic salts 70 doesnot give any direct information about solvation, since attachmentof solvent by the ion will only affect the results in so far as it altersthe volume of the solution.R. P. B.7. KINETIC SALT EFFECTS.The chief contribution made by the interionic theory to reactionkinetics has been by means of the equation first given by J. N.Bronsted in 1922,l according to which the velocity of a reactionbetween A and B is given bywhere the f’s are activity coefficients and X is an intermediate“critical complex.” The exact nature of X is somewhat indeter-minate, so that the value of fx is in general unknown. In the caseof reactions between ions, however, the electrostatic charge of Xmust always be the algebraic sum of the charges on A and B, and thismakes it possible t o predict the variation of the factor fafB/fx withsalt concentration.It is well known that these predictions as tothe sign and magnitude of the salt effect for ionic reactions have beenamply verified, and it is therefore surprising to find that there isG7 Cf. Ann. Reports, 1932, 29, 22.68 H. Frornherz and W. Mewchick, 2. physikal. Chm., 1930, [B], 7, 439;A., 1930, 853; H. Diamond and Fromherz, ibid., 1930, [B], 9, 289; A., 1930,1234; Fromherz and Kun-Hou-Lih, ibid., 1931, [A], 153, 321; A., 1931, 565.Cf. also S . Oka, Proc.Phys.-Math. Soc. Japan, 1933,15, 413; A., 354.v = kcAhfAfB/fX - - * (1)69 J . Ohm. Physics, 1933, 1, 13; A., 1933, 348.70 K. 0. Pedersen, 2. physikd. Ohm., 1934,170, 41.1 Cf. Ann. Reports, 1926,23, 30-37; 1927, 24, 330-33568 GENERAL AND PHYSICAL CHEMISTRY.still considerable difference of opinion as to the theoretical inter-pretation of equation (1).Bronsted's original derivation assumedthat the rate-determining process was the formation of X from Aand B, and justified the form of the equation by rather arbitraryconsiderations. A more generally accepted riew is that of N.BjemmJ3 according to which the term c,cBfJ'B/fX represents theconcentration of a complex in equilibrium with A and B, and thevelocity-determining stage is the decomposition of X at a rateproportional to its concentration.An interpretation of equation (1) in terms of modern views onreaction kinetics has been put forward by V. K. LaMer.4 Accordingto these views, the change in potential energy during an " adiabatic "reaction may be represented schematically by the figure, wherethe co-ordinate x represents some distance which changes duringIXthe course of the reaction, Q is the energy change during the reaction,and A the energy of activation.LaMer identifies the criticalcomplex of Bronsted's theory with the state of maximum potentialenergy (Ex) during the reaction. E , is the potential energy of theinitial state, and for a reaction between A and B can be writtenas EA + EB. If the medium is now altered, e.g., by adding salt,E,, EBJ and Ex will each be changed, and the resulting change inthc heat of activation is given byAA= A E X - A E A - AaE, . . . (2)Further, the reaction velocity ZI is related to the heat of activationby an equation of the formv = PZe-A'RT .. . . . . (3)2. physikal. Chem., 1922, 102, 169; 1925, 115, 337; A., 1922, ii, 699;Ibid., 1924,108, 82; 1925, 118, 251 ; A., 1924, ii, 240; 1925, ii, 131.Chem. Reviews, 1932, 10, 192.Cf. Ann. Reports, 1930, 27, 19.1926, ii, 681BELL: KINETIC SALT EFFECTS. 69where 2 is a collision factor proportional to c,h, and P is a phasefactor which involves inter uZk the relative orientations of themolecules. If therefore it is assumed that P and 2 are unaffectedby the addition of salt, the velocity is given bylog V/Vo = - AA/RT = AEA/RT + AEB/RT - AEx/RT (4)where vo is the velocity in absence of salt. Moreover, if the originalmedium is taken a-s the standard state, the activity coefficientsin presence of salt are given by log fa = AE,/RT, etc., givingv/vo = f d B / f X , which is identical with Bronsted’s formula.It shouldbe noticed that this treatment does not necessarily assume that allsystems reaching the state X will react, but only that the fractiondoing so is not affected by the change in the medium. If this fractionis nearly unity, LaMer’s treatment is equivalent to Bronsted’soriginal derivation, while if it is very small, Bjerrum’s hypothesiswill be valid. The changFs in heat of activation demanded by thetheory are too small to be detected experimentally with certainty.If the Debye-Huckel limiting law is employed for the activitycoefficient% of A, B, and X, and the numerical values of the constantsfor water a t 20” inserted, equation (1) giveslog v/vo = z*zBz/; .. . . . (5)where Z, and are the valencies of A and B and pis the ionic strength.As previously indicated, this equation has received considerableexperimental support, and further work confirms its validity as alimiting law in dilute solution.6 Outside the range of extremelydilute solution it is impossible, in general, to predict the dependenceof the factor f A f B / f X upon Salt, concentration, and there is obviouslyno method of arriving at this experimentally. It has, however,been found that when multiply-charged ions of opposite sign arepresent simultaneously, the limiting laws for activity coefficientsfail even at the lowest concentrations hitherto measured,’ and it isof interest to inquire whether the kinetic salt effect exhibits similarbehaviour.A very suitable reaction for the purpose isCH,Br*CO,’ + S,O,” --+ [XI”‘ + C€€,(S,O,’)-CO,‘ + Br‘where the critical complex has a triple charge. Unfortunately,the experimental evidence is at present very discordant. BothLaMer and Kappamas agree that equation (5) is obeyed in presence6 E.g., V. K. L&cw, J . AWT. Ckm. SOC., 1929, 51, 334; A., 1930, 168;A. N. Keppanna, J . I d k n Chern. SOC., 1929, 6, 45; A., 1929, 516; A. vonKim end I. Boesanyi, 2. anhg. Chem., 1930,191, 289; 1931,198, 102; 1932,206, 196; A., 1930, 1256; 1931, 802; 1932, 702.7 This behaviour can be accounted for by the principle of epecific interaction ;cf. Ann. Reports, 1933, 30, 2470 GENERAL AND PHYSICAL CHEMISTRY.of univalent cations, and von Kiss and A.N. &ppanna and H. W.Pa;twardhan9 find independently that this is also the case in thepresence of magnesium and calcium ions. LaMer and R. W.Pessenden,lo on the other hand, find large deviations from thelimiting law in the latter case, and obtain curves which resemblethe solubility curves of uni-tervalent cobaltammines in salt solutionscontaining bivalent cations.ll Further information on this pointwould be of great interest for the fundamental theory of equation (1).It may be noted in this connexion that LaMer has shown 12 that ifmore than one energy state contributes to the critical con@uration,then fx cannot be strictly interpreted as a thermodynamic activitycoefficient.LaMer and M. E. Kamner l3 have studied the reaction betweenp-bromopropionate and thiosulphate ions, and find a salt effect inthe opposite sense to that predicted by equation ( 5 ) .It is not sur-prising that the simple theory should fail in this case, since the seatof the charge is now some distance from the part of the moleculewhich reacts. LaMer and Kamner account for the negative salteffect by assuming that in the absence of salt the molecules reactingautomatically orient themselves in the most favourable way, whilethe presence of other ions sets up a rapidly fluctuating field whichdisturbs this orientation. This effect [corresponding to a change ofP in equation (3)] must be assumed to be negligible in reactionswhich obey the Bronsted formula. RI. H. Bedford, R. B. Mason,and C.E. Morrell,l* studying the reactions between the thiosulphateion and the ions of brominated malonic and succinic acids, have alsofound a negative salt effect which they attribute to decreasedorientation. The supposed failure of the Bronsted equation in othercases 15 is probably due to its application to solutions not sufficientlydilute to obey the limiting laws.16All the above considerations apply to reactions involving strongelectrolytes, and the effects observed are termed primary salt eflects.If, however, the reactions involve incompletely dissociated electro-lytes, the effect of added salt on the activity coefficients of the ions8 A. von Kiss and P. Vass, 2. anorg. Chem., 1934,217, 305; A., 603.@ Rec. trav. chim., 1932,51, 379; A., 1932, 1210.10 J .Amer. Chem. Soc., 1932, 54, 2351 ; A., 1932, 815.11 Cf. V. K. LaMer and C. F. Mason, ibid., 1927, 49, 363, 410; A., 1927,314; LaMer and R. G. Cook, ibid., 1929, 51, 2622; A., 1929, 1386; LaMerand F. H. Goldman, {bid., 1929, 51, 2632; A., 1929, 1387.12 J . Chem. Physics, 1933, 1, 289.l a J. Amer. Ohem. Soc., 1931, 53, 2832; A., 1931, 1132.14 Ibid., 1934, 56, 280; A., 369.15 V. K. L d e r and J. Greeqan, ibbid., p. 1492; A., 651.16 M. Kilpatrick, &id., p . 2326BELL: ACIDS AND BASES. 71will displace the dissociation equilibrium and hence alter the actualconcentrations of the reacting ions present. The change in reactionvelocity'thus caused is termed a secondary salt eflect, and is ofparticular interest in the study of catalysis by weak acids or weakbases.17 Many examples of the distinction between the primaryand secondary effects are given by 5.N. Bronsted.18In principle, there is no reason why equation (1) should be re-stricted to reactions between ions. In practice, however, no generalpredictions can be made about fx for reactions between an ion anda, neutral molecule or between two neutral molecules, althoughsome attempts have been made in this dire~ti0n.l~R. P. B.8. ACIDS AXD BASES.The classical conceptions of acids and bases have undergonegreat changes in the last ten years or so, and the new ideas have nowbecome so generally accepted that a general review of recent develop-ments in the subject may be of interest. For many years acids andbases were defhed as substances giving rise respectively to hydrogenions and hydroxyl ions in aqueous solution. This definition couldbe extended without much difficulty to other hydroxylic solventsby substituting, e.g.the ethoxide ion for the hydroxyl ion, and theposition was rendered more symmetrical by the gradual realisation 1that the " hydrogen ion " is never simply a proton H', but existsentirely in water as H,O', in alcohol as C,H6~O€€,', etc. Suchideas, however, admit the existence of acid and basic attributesonly in the presence of a suitable solvent, and such a reaction asthe combination of ammonia, and hydrogen chloride in the gasphase or in benzene solution would not be classed as an acid-basereaction. The inadequacy of such a point of view appears stillmore clearly when it is realised that benzene solutions of acidsand bases exhibit such typical behaviour as indicator reactions 21 7 See this Report, p.72.la Chena. Revbw8, 1928,5,266; Tram. Farrad&y Soc., 1928, 24, 630.18 0. Scatchard, Chem. Reviews, 1932, 10, 236; H. Harned and N. N. T.Samaras J . Amer. Cbm. SOC., 1932,54, 9; A., 1932,346; Samaras, J . PhysicalChem., 1933.37, 437.1 See, e.g., H. Goldachmidt and 0. Udby, 2. phy8ikaZ. Cherra., 1907, 60,728; A., 1907, ii, 862; K. Fajans, Rer. phy8ikal. am., 1919, 21, 709; A.,1920, ii, 12; A. Hmtzach, 2. EkUrochem., 1924, So, 194; K. Fajena asd G.Joos, 2. Physik, 1924, 25, 1; A., 1924, ii, 372; G. Scatchard, J . Amer. Chen~.Sot., 1926,47,2098; A., 1926, ii, 971; T. M. LOW, J., 1926,1372; A., 1925,i, 886; J.N. Bronsted, J . P h y d Chm., 1926, So, 777; A,, 1926, 797.3 J. N. Bronsted, Ber., 1928, 61, [B], 2049; A., 1928, 1188; A. Hantzmhand W. Voigt, *id., 1929, a, [B1, 970; A., 1929,66672 GENERAL AND PHYSICAL CHEMISTRY.and electrometric titration: although there are no hydrogen ionspresent, and no possibility for the existence of hydroxyl ions ortheir analogues.The matter was put on a much more logical basis by 5. N.Bronsted4 and T. M. Lowr~,~ who almost simultaneously proposedas a definition that an acid is any substance tSaving a tendency to losea proton, and a h e i s any substance having a tendency to take upa ppr020n. Acids and bases thus form corresponding pairs, relatedby equations of the typesuch pairs are CH,*CO,H and CH,43O,', NH,' and NH,, H,O' andH,O, etc.It should be noted that there is no restriction as to thecharge on an acidic or basic molecule, but that there is always unitdifference of charge between a corresponding pair. This apparentlyformal definition not only rationalises our general ideas about acidsand bases, but by extending the terms acid and base to such speciesesNHp' and CH,GO,',it has led to important discoveries inconnexionwith acid and basic catalysis. In particular, it shows that OH' and8,O' do not occupy any unique position among acids and bases,except in so far as they are formed from the solvent itself.Since a free proton can never exist in the presence of othermolecules, equation (1) does not represent an observable process.The actual acid-base equilibria which we study are obtained bycombining two such equations, givingA e B + H ' .. . . . (1)A l + B , e = A , + B 1 . . . . . (2)A,, B1, and A,, B, being two corresponding acid-base pairs. Aspecial case of this is when one of the acid-base pairs is providedby the solvent, giving, e.g.,CH3C02H + H,O s H30' + CH,CO,'acid 1 base 2 acid 2 base 1base 1 acid 2 base 2 acid 1NH, + HzO e= OH' + NH,'In this case water can act either as a base or as an acid, the cor-responding acid and base being H,O' and OH'. This point of viewhas brought into clearer relief the essential part played by the solventin the dissociation of acids and bases, and greatly simplifies thetreatment of problems such as hydrolysis and buffer solutions.These considerations have also an important bearing on the8 V.K. LaMer and IF. C. Downes, J . Amer. Chem. Soc., 1931, M, 888;4 Rsc. trav. chim., 1923, 42, 718.5 Chsm. and Ind., 1923, 42, 43; A., 1923, ii, 849.A., 1931, 684B3ELL : -4CIDS AND BASES. 73quantitative definition of acid and basic strength, and as there isconsiderable confusion about the different constants used we shalloutline the position here.6 The most logical definition would beon the basis of equation (l), i.e.,Kaoid = a H * c B / c A ; Kbsge = cA/cBaH. . * . (3)where the C’s are concentrations, and a=* is the proton activity.These constants are a direct measure of the tendency of the moleculesto lose or gain a proton, and may be termed absolute acidity con-stants.They are, however, of no service in practice, since we cannotmeasure aH-, and it is probably in principle indefinable.‘ The typeof equilibrium actually studied involves two acid-base pairs, andfrom equation (2) we can define an equilibrium constant byI< = C A , C B 1 / C ~ l C ~ l . . . . ‘ (4)If one acid-base pair is kept the same, this constant provides ameans of comparing the acid or basic strengths of the other pairsinvolved. The natural standard to use is the solvent, and we maythus define the so-called “ rational constants,” which for aqueoussolutions becomeKA (rat.) = C ~ C ~ ~ ~ * / C ~ C ’ ~ s ~ ; KB (rat.) = CACo,*/CBCH,o ( 5 )The rational acidity constant may be considered as the ratio of theabsolute acidity constant of the acid to that of the solvent, andsimilarly for the basicity constants.Since the concentration ofwater is constant, the rational constants are proportional to theconventional dissociation constants, according to the equationsK A = K A (rat.) x C=,o = CBCE,,./CASimilar sets of constants can obviously be defined for any othersolvent capable of acting both as an acid and a base. The con-stants in equations (4)-(6) are not true thermodynamic constants,but may be related to them by introducing a term involvingactivity coefficients, e.g.,K ’ A and K A becoming identical in infinitely dilute solution.1 * ‘ (6) KB = KB (rat.) x CHs0 = CAC,H*/CBK I A == aBaH,O*/aA == KAfBfH30’/fA * * (7)The best methods for measuring dissociation constants are those6 The quantitative statement of the problem was &st given by Bronstedin a Danish monograph “ Om Syre og Basekatalyse ” (Copenhagen? l926),Later translated into English (Chem.Reviews, 1928, 3, 231). Other papersby Bronsted are: Be?.., 1928, 61, [B], 2049; A., 1928, 1188; 2. physikal.Chem., 1934, 169, 52; A., 962.7 See E. A. Guggenheim, J . Physical Chem., 1930, 34, 1758; A., 1930,1124; P. B. Taylor, ibid.. 1927, 31, 1478; il., 1927, 1141.c 74 GENERAL AND PHYSICAL CHEMISTRY.involving measurement of the concentration of one of the speciespresent. In the case of coloured substances, this may be done veryaccurately by means of modern colorimetric technique, which hasbeen employed by P. Gross, A. Jamock, and F.Patat for measuringthe dissociation constant of picric acid in ethyl alcohol and by H.voii Halban and G. Kortum9 for dinitrophenol in aqueous saltsolutions. L. P. Hammett, A. Dingwall, and L. E'lexser10 haverecently extended the same method to colourless solutions byworking in the ultra-violet. The catalytic method was one of thefirst to be used for measuring hydrogen-ion concentrations, and ithas recently been used for accurate measurements on monochloro-acetic acid l1 and for measuring dissociation constants in ethylalcohol.12 The derivation of accurate dissociation constants fromconductivity data is rather more complex, involving the variationof mobility with concentration, but convenient methods of com-putation have recently been devised.13 Accurate work of this kindhas been done recently by D.A. McInnes and by D. J. G. Ives.I5Most of the methods based on the E.H.F. of cells are not suited foraccurate measurements, as they involve indeterminate junctionpotentials, but Harned has recently devised a method using onlyconcentration cells without liquid junctions, and accurate datahave been obtained for a number of acids and bases at differenttemperatures.16 It is gratifying to note that the value obtainedby McInnes for the thermodynamic dissociation constant of aceticMonat8h., 1933, 63, 117.2. Elektrochem., 1934, 40, 502; A., 962.lo J. Amer. Chem. SOC., 1934, 56, 2010; A., 1173. For a new type ofspectrophotometer suitable for such work, see L. A. Woodward, Proc. Roy.SOC., 1934, [A], 144, 118.C.Grove, J . Amr. Chern. SOC., 1930, 52, 1404; A., 1930, 698.12 A. J. Deyrup, ibid., 1934, 56, 60; A., 260.l3 See this Report, p. 65.l4 J. Amer. Chem. SOC., 1926, 48, 2068; A., 1926, 906; McInnes and T.Shedlovsky, ibid., 1932, 54, 1429; A., 1932, 695; cf. also B. Saxton andT. W. Langer, ibid., 1933, 55, 3638; A., 1933, 1118.l6 J., 1933, 731; A., 1933, 780.16 H. S. Harned and B. B. Owen, J. Amer. Chm. Soc., 1930, 52, 5079;A., 1931, 308 (acetic and formic acids, aliphatic amines, and glycine at 25') ;Harned and R. W. Ehlers, ibid., 1932, 54, 1350; A., 1932, 695 (acetic acid,0-35"); ibid., 1933, 55, 652; A., 1933, 350 (acetic acid, 0-60"); ibid., 1933,55, 2379; A., 1933, 780 (propionic acid, 0-60"); B. B. Owen, ibid., 1934,56, 24; A., 254 (glycine, 10-45'); ibid., 1934, 56, 1695; A..1071 (boricacid, 10-50") ; D. A. McInnes and D. Belcher, ibid., 1933, 55, 2630 (carbonicacid a t 25"); Harned and R. 0. Sutherland, ibid., 1934, 56, 2039; A., 1307(n-butyric acid, 0-60"); Harned and N. D. Embree, ibid., 1934, 56, 1042;A., 731 (formic acid, 0-60"); L. F. Nirns, ibid., 1934, 56, 1110; A., 731(phosphoric acid, 0-40"); D. D. Wright, ibid., 1934, 56, 314; A., 364 (mono-chloroacetic acid, 0-40O)BELL: ACIDS AND BASES. 75acid at 25" (1.753 x is almost identical with the value obtained byHarned and Ehlers using an entirely different method (1.754 x 10-5).Instead of measuring directly the equilibrium with the solvent,it is often convenient to add a third acid-base system havingcoloured components, i.e., an indicator.If, then, the equilibriumconstant between the indicator and the solvent is known, measure-ments of the concentrations of the two forms of the indicator presentwill give the position of the equilibrium between the first acid-basesystem and the solvent. The method has, of course, been thoroughlyworked out for aqueous solutions,17 but considerable care is neces-sary in transferring the method to other solvents without indepen-dent investigation, as it has been found in some cases that theabsorption spectrum of the indicator varies considerably with thenature of the solvent l8 and that the colour change may even takeplace in different stages in different solvents.19Since at least two of the activity coefficients in equation (7) referto ions, the Debye-Huckel theory may be used to predict the varia-tion of the dissociation constant with ionic strength.I f , in theequilibrium A + H,O z+= B + H,O', the (positive) valency of A isx, the limiting law for water a t 20" is easily shown to bewhere p is the ionic strength. The case x = 0 corresponds to thedissociation of an ordinary uncharged acid, and the correspondingincrease of dissociation constant with increasing ionic concentra-tion is amply confirmed by the accurate measurements quotedabove.20 For equilibrium between ammonia and the ammoniumion (or the analogous case of an amine), x = 1, and as predicted bythe equation there is very little change of dissociation constant withsalt concentration in dilute solution.Bronsted21 has made aninteresting experimental study of equilibria of the typelog10 KA = log10 K'A - ( X - 1)dt.L . . . (8)(OH) ** [(3(H,O),I**' + H2O =e P(H20),l + H,O*l7 For recent work, see, e.g., N. V. Sidgwick, W. J. Worboys, and L. A.Woodward, Proc. Roy. Soc., 1930,129, [A], 627; A., 1931, 39; Sidgwick andWoodward, ibid., 1930,180, 1 ; A,, 1931, 168; E. A. Guggenheim and F. D.Schlinder, J. Ph3/sical Chem., 1934, 88, 643.H. Baggesgaard-Rasmussen and F. Reirners, Damk Tidsskr. Farm.,1933,7, 225; A., 1934, 160.1s See, e.g., J. N. Bronsted, A. Delbanco, and A. TovborgJensen, 2.physikal. Chem., 1934,169, 361 ; A., 1070.20 See especially McInnes and Shedlovsky, Zoc. cit., ref. (14); Shedlovsky,A.S. Brown, and D. A. McInnes, Tram. Amer. EEectrochm. S'OC., 1934, 66,237; A,, 1308.21 J. N. Bronsted and C. V. King, 2. physikal. Chm., 1927, Cohen-Festband,699; A,, 1927, 204; Bronsted and K. Volqvartz, &id., 1928, 134, 97; A.,1928, 132676 GENEEAL AND PHYSICAL CHEMISTRY.corresponding t o x = 3, and finds the expected large decrease ofdissociation constant with increasing ionic concentration.There have been a number of attempts to employ equation (3)for defining an absolute scale of acidity by means of which acidsin different solvents can be compared,22 but it seems probable thatall such definitions must be at best completely arbitrary, since theyinvolve such difficultly accessible concepts as individual ionicactivities and potential differences between two phases.' It is,however, possible to obtain much interesting information by com-paring the rational or conventional dissociation constants in differentmedia, and to obtain a semi-quantitative interpretation of the results.It is now generally realised that the acidic or basic character of thesolvent is by far the most important factor affecting the behaviourof dissolved acids or bases.Water and other hydroxylic solventshave been termed by Bronsted '' amphiprotic," since they are ableeither to receive or to lose a proton, and thus act as strongly dis-sociating media for both acids and bases. Recently, a great deal ofinteresting work has been done with very acid solvents, i.e., solventswhich readily lose a proton but accept one only with difficulty.As long ago as 1908, A.Hantzsch 23 showed by cryoscopic investig-ations in sulphuric acid that nearly all oxygen compounds can actas bases provided they be dissolved in a medium of sufficient acidity,but it is only recently that quantitative measurements have beencarried out in this type of solvent. Conant and his collaborators 24have carried out electrometric and indicator studies of a, largenumber of acids and bases in anhydrous acetic acid, and con-ductivity work in the same solvent has been carried out by a numberof authors.25 Two interesting points emerge : in the first place,all bases which in water are stronger than aniline give identicaltitration curves in acetic acid, and may be considered as strongZ2 J.N. Bronsted, 2. physikal. Chem., 1929, 143, 301; A., 1929, 1240;Bronsted, A. Delbanco, and K. Volqvartz, &id., 1932, 163, 128; A., 1933,26; L. P. Hammett, J. Amer. Chm. SOC., 1928, 50, 2666; A., 1928, 1325;G. Schwarzenbach, Helv. Chim. Acta, 1930, 13, 870; A., 1930, 1526.23 2. physikal. Chem., 1908,61, 257; 65, 41; A., 1908, ii, 14,462.24 J. B. Conant and N. F. Hall, J. Amer. Chem. SOC., 1927, 49, 3062; A.,1928,129; Hall and Conant, ibid., 1927,49, 3047; A., 1928,129; Conant; andG. M. Brammann, ibid., 1928,50,2305; A., 1928,1101 ; Halland T. H. Werner,ibid., 1928, 50, 2367; A., 1928, 1118; Conant and Werner, ibid., 1930, 52,4436; A., 1931, 40.25 A. Hantzsch and 1%'. Langbein, Z . ccnorg. C'hem., 1932, 204, 193; A.,1932, 467; F, G.Hall and H. H. Voge, J . Amer. Chern. SOC., 1933, 55, 239:A., 1933, 230; W. C. Eichelbergcr and V. K. LaMer, ibid., 1933, 55, 3636;A., 1933, 1121 ; I. M. Kolthoff and A. Willan, ibid., 1934, 56, 1007 ; A., 735 ;13. V. Weidner, A. W. Hutchinson, and G. C. Charidlee, ibid., 1934, 56, 1285;A., 846BELL : AUIDS AND BASES. 77bases. It is not correct to describe them as completely dissociated,since the low dielectric constant of the solvent will favour considerableion-pair formation, but the '' protolytic " reaction, e.g., CH,-NH, +CH3*C02H -+ [ CH,-NH,]' [CH,*CO,]', has taken place completely.In the second place, a number of acids which in water are completelydissociated (e.g., hydrochloric, perchloric, sdphuric, and benzene-sulphonic) give widely differing titration curves in acetic acid.The conductivity measurements are more difficult to interpretowing to the strong interionic forces, but they support the differencesbetween the " strong " acids.Similar results have been obtainedwith anhydrous formic acid as a solvent by Hammett,26 who inparticular has discovered a large number of indicators suitable foruse in such solvents. A medium of continuously varying aciditycan be made by mixing sulphuric acid and water in varying pro-portions, and although the strong buffer action in such a mixturemakes electrometric and conductivity measurements useless,Hammett and Deyrup2' have studied a large number of basescolorimetrically in this solvent, ranging from p-nitroaniline, whichis appreciably ionised in water, to trinitroaniline, which is in-completely ionised even in concentrated sulphuric acid.HammetLhas also investigated a number of indicators in the same solvent,28and both he29 and J. W. Baker30 have shown how solubility andpartition methods may be used for studying basic properties. Manycompounds exhibiting hardly any basic properties in water (e.g.,esters, ketones, oximes, amides) are strong enough bases in thesesolvents to permit of quantitative titration, a fact which may prove ofpractical importance .Next to the acidic or basic character of the media involved, themost important factor governing the change o€ dissociation constantwith change of medium is the electrostatic energy of the ions.This appears most clearly by considering the two typical pairs ofdissociation equilibria,NH,' + H,O NH, f N,O'NH,' + CH,*OHCH,*CO,H + H,O s CH,*C02' + H,O'CH,=CO,II + CH,*OHNH, + CH,*OH,'CH,*CO,' + CH,*OH,'26 L.P. Hammett and N. Dietz, J. Amer. Chem. SOC., 1930, 52, 4795; A.,z7 Ibid., 1932, 54, 2721; A., 1933, 26.28 L. P. Hammett and M. A. Paul, aid., 1934,56, 827; A., 618.2s L. P. Hammett and R. P. Chapman, ibid., p. 1282; A., 839.30 J., 1931, 307; A., 1931, 485; J., 1932, 1226; A., 1932, 612; Baker and1931, 312; Ha,tnmett and A. J. Deyrup, ibid., 1932, 54, 4239; A., 1933, 26.L. Hey, ibid., p. 2917; A., 1933, 16978 GENERAL AND PHYSICAL CHEMISTRY.In going from water to methyl alcohol, the effect of the changedsolvation of the proton is the same for (a;) as for (b), but the effectof the change of electrostatic energy is obviously much greater for( b ) . Correspondingly, it is found that the dissociation constant ofacetic acid decreases by a factor of about lo4 in passing from waterto methyl alcohol, while that of the ammonium ion decreases onlyby a factor of about lo2.This was first pointed out by N. Bjerrumand E. Larsson 31 and by Bronsted 32 and is supported by a largeamount of evidence.33 This principle has recently been appliedto a study of some amino-acids, where the shift in the titrationcurve in going from water to alcohol can be used to establish whetheror not the amino-acid is present as a “ zwitterion.” 34There is a considerable amount of evidence to show that the ratioof the dissociation constants in two media is approximately the samefor all acids of the same charge type,35 but closer examination showsthat this is only true to within a power of ten ; this is well shown bythe work of J.0. Halford on alcoholic solutions,36 of M. and M. L.Kilpatrick in the weakly basic solvent a~etonitrile,~~ and of Bronstedin the acid solvent rn-~resol.~~ The available data have been re-viewed by W. P. K. Wynne-Jone~,~~ who has shown that from atheoretical point of view the individual deviations are due todifferences between the transfer energies of the individual acid orbase molecules (or ions) wit,hin each class. These differences willbe small for a series such as the aliphatic carboxylic acids, but maybe considerable when comparing e.g., ions of the phenoxide andthe cmboxylate type.Wynne-Jones has deduced on the basis ofelectrostatic theory a quantitative relationship between the relativedissociation constants in different solvents, on the assumption that31 2. physikal. Chem., 1927, 127, 358; A., 1927, 928.32 J . Physical Chem., 1926, 30, 777; A., 1926, 797.33 See, e.g., L. Michaelis and M. Mizutani, 2. physikal. Chem., 1925, 116,135 ; . A., 1925, ii, 793 ; Mizutani, ibid., 1925, 116, 318, 350 ; A., 1925, ii, 867 ;ibid., 1925, 118, 327; A., 1926, 125; L. D. Goodhue and R. M. Hixon,J. Amer. Chem. Soc., 1934, 56, 1329; A., 735.34 See, e.g., T . H. Jukes and C. L. A. Schmidt, J . BioZ. Chem., 1934, 105,359 ; A., 732 ; J. T. Edwall and M. H. Blanchard, J. Amer. Chem.SOC., 1933,55, 2337; A., 1933, 781.35 Bjerrum and Larsaon, loc. cit., ref. (31); H. Goldschmidt, C. Gorbitz,H. Hongen, and K. Pahle, 2. physikal. Chem., 1921, 99, 116; A., 1922, ii,135; W. I,. Bright and H. T. Briscoe, J . Physical Chem., 1933, 37, 787; A.,1933, 904.36 J. Amer. Chem. Soc., 1933, 55, 2272; A., 1933, 780.37 Chenz. Reviews, 1933, 13, 131.38 J. N. Bronsted, A. Delbanco, and A. Tovborg-Jensen, 2. physikd. Chem.,30 Proc. Roy. SOC., 1933, [A], 140, 440; A., 1933, 675.1934,169, 52; A., 962BELL: ACIDS AND BASES. 79the radii of the ions (excluding the solvated proton) remain mnsta3nt,and that the non-electrostatic transfer energies are negligible. Hisequation agrees with the scanty data available for water and thealcohols.As a basis for comparing different acids or bases (e.g., forinvestigating the relationship between constitution and acid orbasic strength) he suggested the USC of the “intrinsic strength,”obtained by extrapolating the results for different solvents to ahypothetical solvent of infinite dielectric constant, thus eliminatingpurely electrostatic effects.40 Since water has such a high dielectricconstant, this extrapolation can be easily carried out from theresults in water and the alcohols.Considerable interest attaches to tho behaviour of acids and basesin solvents such as benzene (termed by Bronsted “aprotic ” solvents),which possess neither acid nor basic properties. Since the solventcan take no part in a protolytic equilibrium, it is always necessaryto add a second acid or base before any measurements can be carriedout.By a suitable choice of this auxiliary acid or base, any desiredrange of acid or basic strength can be studied, whereas in solventswhich themselves possess acid or basic properties, this range islimited. Thus, in water, all acids considerably stronger thanH,O’ or bases considerably stronger than OH’ will be completelydissociated, and will therefore appear to be equally strong. (Thisproperty of water and the other hydroxylic solvents has been termed“nivellierend” by Hantzsch.) A scale of acidity in an aproticsolvent is most conveniently constructed by the use of indicators,and this has been done for benzene by Bronsted41 and by V. K.LaMer and H. C. and in chloroform by A.Hantzsch andW. Voigt.@ It has also been found possible to carry out electro-metric titrations in this type of solvent.44 It was found that therelative strengths obtained were approximately the same withdifferent indicators, and that the titration curves for a given acidwere the same when the titration was carried out with different strongbases. This seems to indicate that the changes investigated actuallydo involve a proton transfer, though the low dielectric constant ofthe medium obscures many of the usual properties of the saltsformed. It is a striking fact that the order of acid strengths found isessentially the same as in water, The results are, however, verydifficult to interpret exactly, as the acid-base systems (including40 Cf.also J. N. Bronsted, 2. physikal. Chem., 1934,109, 52; A., 962.4 1 Ber., 1928, 01, 2049; A., 1928, 1188.43 Ber., 1929, 02, [B], 970; A., 1929, 666.44 V. I(. LriMer and H. C. Domes, J . Arner. Chem. Soc., 1931, 53, 888;42 J . A W ~ . them. soc., i933,55, ia40; A., 1933,675.A., 1931, 58480 GENERAL AND PHYSICAL CHEMISTRY.the indicators) are often associated to a great extent; thus allcarboxylic acids exist essentially as double molecules in these sol-v e n t ~ . ~ ~ This probably accounts for some of the anomalous results ;e.g., LaMer and Domes found titration and dilution curves havinghalf the theoretical slope. Owing to the absence of free ions, theelectrostatic effects considered by Wynne-Jones will be a t any ratemuch reduced, which may explain why the relative strengths arefound to be roughly the same as in water, in spite of the very lowdielectric constant.R. P. B.9. MISCELLANEOUS SUBJECTS.The range of subject matter studied during the past year andnot included in the foregoing sections of this report is a wide one,and reference can only be made in broad outline to the more pro-minent lines of investigation.The application of X-ray and electron-diffraction methods to thedetermination of molecular structures has been extended to a largevariety of compounds.l Attention should also be drawn to twodiscussions held during the year ; in oneY2 dipole-moment measure-ments have been considered in reference to molecular structure,and such matters as the resonance between linkages in moleculesand free rotation have been examined; in the other,3 free radicalsof varying life have been described and discussed in different con-nexions. Reference should also be made to two accounts on subjectsnot easily accessible or frequently understood : D.C. Darrow hasdescribed briefly the essential principles of the wave and quantummechanics> and J. C. Slater has dealt with the electron theory of45 Cf. R. P. Bell, E. C. Baughan, and M. W. Vaughan-Jackson, J., 1934,1969.1 See, e.g., S. B. Hendricks, L. R. Maxwell, V. R. Mosley, and M. E. Jefferson,J. Chem. Physics, 1933, 1, 549; A., 1934, 17; F. L. Amot, Proc. Roy. SOC.,1934, [A], 144, 360; A., 577; F. B. Slagle and E. Ott, J. Amer. Chem. Soc.,1933,55,4396,4404; A., 1934,17; R.W. Dorute, J . Chem. Physics, 1933,1,566,630; A., 18; W. C. Pierce, {bid., 2, 1 ; A,, 244; 0. Stelling, Z. physikal. Chem.,1934, [B], 24, 282; A., 352; W. T . Astbury and H. J. Woods, Phil. Trans.,1933, [A], 232, 333; A., 352; R. 0. Jenkins, Phil. Mag., 1934, [vii], 17, 457;A., 352; L. Pauling and J. Sherman, Proc. Nat. Acad. Sci., 1934, 20, 340;A., 948; (Sir) W. H. Bragg, Nature, 1934,134, 138; A., 948; J. M. Robertson,Proc. Roy. SOC., 1934, [A], 146, 473; A., 1297; M. L. Huggins and J. E.&layer, J. Chem. Physics, 1933, 1, 643; A., 1934, 16; see also (Sir) W. H.Bragg, Proc. Roy. Inst., 1934, 28, 57; A., 478; Trans. Faraday SOC., 1934,30, 665.Ibid., pp. 679-900.Ibid., pp. 3-245.J Bev. Mod. Physics, 1934, 6, 23THOMPSON : MISCELLANEOUS SUBJECTS.81~netals.~ The theory of the Alternative Atom, suggested by J.Tutin,6 has proved unserviceable.’In the following, an attempt has been made t o classify varioustopics under appropriate headings.Emission of Electrons in Chemical Change.-A. K. Denisoff and0. W. Richardson * have continued their interesting work on theemission of electrons under the influence of chemical reaction, aphenomenon not discussed for some time in these Reports. It haslong been known that when the sodium-potassium alloy, NaK,, isbrought into contact with certain reactive gases such as halogensor carbonyl chloride, a t low pressure, electrons are emitted. Moredetailed examination now shows that each of a variety of gases orvapours may be used, e.g., carbonyl chloride, chlorine, bromine,iodine, nitrosyl chloride, carbonyl sulphide, sulphur chlorides,sulphuryl chloride, mercuric chloride.With gaseous hydrogenchloride or with steam, the effect is less marked, and with nitrousoxide apparently absent. It is found that the electron emissionincreases uniformly with pressure up to a certain value, falling offagain at higher pressures. The distribution of energy among theemitted electrons is not Maxwellian, but of a similar form, havinga maximum. The important result is that the emission yield de-creases as the available energy produced from the chemical reactiondecreases, so that Emax. = Echem. - +, where Em=, is the maximumenergy of an electron, Echem. the chemical energy derivable from thereaction, and 4 is the work function of the metal.Denisoff andRichardson consider that, in general, a polar bond is first formed,this being stabilised by a three-body collision with the free metallicelectron, which subsequently takes away all the surplus reactionenergy. The relationship given above at once recalls the photo-electric effect. Assuming its general validity, a determination ofEm=. for any given reaction may lead to a deduction of Echem.,which in its turn may provide the criterion for deciding which ofseveral possible elementary processcs is involved in the reaction.It is therefore clear that these experiments have, in a limited waya t least, some importance in connexion with the kinetics of hetero-geneous chemical reactions.Xpectroscopic Considerat ions.-Perhaps the greatest accumulationof experimental data has occurred in that field which deals withthe study of chemicophysical problems by the methods of spectro-“ The Atom,” Longmans, 1934.7 R.H. Fowler, Nature, 1934, 133, 852.8 Proc. Roy. SOC., 1934, 144, [A], 46; A., 468; ibid., 146, [A], 524; A.,1282; ibid., 145, [A], 18; A., 937; cf. also F. Haber and K. Just, A m .Phy8ik, 1911, s8, 308.Rev. Mod. Physics, 1934, 6, 20982 GENERAL AND PHYSICAL CHEMISTRY.scopy. The infra-red and ultra-violet absorption spectra of manyinorganic and organic polyatomic molecules have been measured,both in the vapour and the liquid state.9 The primary objects ofsuch work are to determine the stereochemical and electronicstructures of the molecules, the energies of linkage, and the mechan-ism of chemical reactions which the molecules undergo; the prin-ciples involved have been discussed in previous Reports.lo A com-parison of the spectra of some simple molecules containing hydrogenH1 with the corresponding compounds of deuterium H2 has beenmade (this vol., p.15).A catalogue of the new material would exceed the scope of thisReport, but in any case discussion would be premature until it hasbecome more systematised and the theoretical aspects more clearlyunderstood. A particularly interesting study is that of the ab-sorption spectrum of the volatile osmium tetroxide, OsO,; l1and a somewhat unusual method has been employed by G. B.Kistiakowsky and H. Gershinowitz l2 in the determination ofthe C-C linkage energy in cyanogen molecules.From measure-ments of the pressures at which absorption bands due to CN,produced by the dissociation of cyanogen a t different temperaturesin the region of 1200", have equal intensity, these workers obtaina value of 77 & 4 kg.-cals. per g.-mol., which agrees well with existingthermochemical data. From measurements on absolute intensityof the infra-red vibration bands of hydrogen halide gases,E. Bartho1om6l3 concludes that these molecules contain a homo-polar link. The limitations, indicated previously, of the use ofspectral measurements in deciding the mechanism of photochemicalprimary processes have again been emphasised by several authors ; l4measurements on fluorescence taken in conjunction with the spectraldata, although essential, may also prove not unambiguous.More examples have been reported of the emission spectra of@ See, e.g., H.Conrad-Billroth, 2. physikal. Chm., 1933, 23, [B], 315; A.,1934, 8 ; R. Schaffert, J . Chem. Physics, 1933,1, 607; A., 1934,9; H. VedderandR. Mecke, 2. Physik, 1933,80, 137; A., 1934,9; G. Hettner, R. Pohlman,and H. J. Schumacher, Naturwiss., 1933, 21, 884; A., 1934, 129; P. K.Sen-Gupta, Proc. Roy. SOC., 1934, [A], 143, 438; A., 237; J. Lecomte, Compt.Tend., 1934,198, 65; A., 238; G. H. Dieke and G. B. Kistiakowsky, PhysicalRev., 1934, [ii], 45,4; A. Glissmann and H. J. Schumecher, 2. physikal. Chem.,1934, 24, [B], 328; A., 344; H. W. Thompson and A. P. Gmatt, J., 1934,624; A., 582.lo Ann.Reports, 1933, 30, 79; 1932, 29, 47; 1931, 28, 367; 1930, 2'7, 21.l1 A. Langseth and B. Quiller, 2. physikal. Chem., 1934, 2'7, [B], 79.la J . Chem. Physics, 1933,1, 432; A., 1934, 30.la 2. physikal. Chem., 1933,23, [B], 131; A., 1933, 1227.l4 Cf. Royal Society Discussion on Energy Distribution, Proc. Roy. Soc.,1934,140, [A], 239THOMPSON : MISCELLANEOUS SUBJECTS. 83highly ionised atoms. Typical examples are those of Bi IV, 0 111,F ~ I I I I V , Br VVTVII, C~IIIIVV, S b ~ ~ m , A u n , Ran, SII, CIII.H. Beutler and K. Guggenheimer l5 have studied the absorptionspectra of the vapours of mercury, cadmium, zinc, potassium, andczsium in the extreme ultra-violet ; these arise from an excitation ofinner electrons and frequently involve levels which ‘‘ predissociate ”into an electron and ionised atoms.The existence of the polarisation molecule 0,, originally suggestedby G.N. Lewis l6 from measurements on the magnetic propertiesof liquid oxygen, has now been examined by spectral methods,consisting essentially in an analysis of the absorption spectrum ofhighly compressed oxygen gas or of the liquid. W. Steiner,17H. Salow and W. Steiner,ls and R. Guillien,lQ have now establishedthe existence of this complex. W. Finkelnburg 2O has summarisedcritically all the relevant data on the subject, and from an analysisof the absorption bands at high pressures has obtained a value forthe 0,-0, link energy of some hundredths of a volt, Le., cu. 0.2kg.-cal. per g.-mol., in fair a.greement with Lewis’s original value.It seems probable that other similar polarisation molecules exist,the failure to detect them being due to difficulties of obtaining therequisite conditions.From an analysis of a new hydrogen resonance spectrum in thefar ultra-violet, obtained in a discharge tube containing hydrogenand argon, H.Beutler has determined the energies of dissociationof hydrogen Hi, deuterium Hi, and of HIHa. The values per g.-mol.are 102.7, 1046, and 103.5 kg.-cals. From a consideration of certainpredissociation phenomena in nitrogen bands reported by A. van derZiel,e2 G. Herzberg and H. Sponer 23 have recalculated the energyof dissociation of the nitrogen molecule and obtain a value 169.3kg.-cals. per g.-mol.P.K. Sen-Gupta 24 has considered the different types of absorptionspectrum from the standpoint of the Franck-Condon principle.The spectroscopic examination of the flame spectrum of ethylene 25suggests the presence of an emitting molecule HCO.3, 124, 231, 467, 1280.l5 2. Physik, 1933, 86, 495, 710; 87, 19, 176, 188; 1934,88, 25; A., 1934,l6 J . Amer. Chem. Soc., 1924, 46, 2027.Tram. Paraday SOC., 1934,80, 34; A., 242.l8 2. Phy&ik, 1934, 90, 11; A., 1055; Nature, 1934,134, 463; A,, 1153.Compt. rend., 1934,198, 1223, 1486; A., 472, 580.2o 2. PhysQ, 1934, 90, 1; A., 1055.21 2. phy8ikal. Chem., 1934,27, [B], 287.22 Nature, 1934, 133, 416.24 Z. Phy&k, 1934, 88, 647; A., 715.2s W. M. Vaidye, Proc. Roy. Soc., 1034, 147, [A], 513.23 2.physikal. Chem., 1934, 26, [B], 184 GENERAL AND PHYSICAL CHEMISTRY.The Neutrino (see also p. 394).-In the construction of a theoryof nuclear electrons and 13-ray emission there are two difficulties,first the continuous nature of the p-ray spectrum, and secondlythe fact that the theory of relativity of light particles cannotexplain satisfactorily how electrons may remain bound in orbitswith dimensions of nuclear magnitude. The latter difficulty woulddisappear if the nuclei contained no electrons, and this is theessential feature of Heisenberg’s theory, which regards the nucleusas built up of protons and neutrons. If, however, the process ofb-ray emission is to be regarded as a quantum process, it is diffi-cult to reconcile the continuous P-ray spectrum with the law ofconservation of energy.Fermi has accordingly suggested thatsimultaneously with the emission of a P-particle, another particleis emitted, of mass comparable with, or less than, that of theelectron and carrying no charge. The process of @-ray decay isthenA comparison of this process with that involving the emission ofradiation from an excited atom leads to a calculation of the decom-position probability, i.e., the life of the neutron state. Fermi hasalso obtained a relationship, similar in nature to the Geiger-Nuttallequation for or-ray decay, which expresses the variation of themaximum momentum of @-particles emitted by a given elementwith its average life. Again, by analogy with “probable” or“ forbidden ” transitions in the theory of radiation, it is found herethat the radioactive elements should, as regards @-ray decay, fallinto two groups, the one of short life, the other ‘of long life.Examination of the experimental data supports this conclusion.Details are given elsewhere in these Reports.Nuclear &foments.-Measurements of the mcchanical and magneticmoments of nuclei from hypedine structure or the polarisation ofresonance radiation have rapidly multiplied since the last Report.26Typical cases studied are Be, Xe, Nay Tat, P, Zn, Te, Se, Sb, Sn.27See, e.g., E.Gwynne-Jones, Nature, 1933, 132, 781; A., 1934, 2; L. P.Granath and C. M. van Alta, Physical Rev., 1933, [ii], 44, 935; A., 124;M. F. Ashley, ibid., p. 919; A., 124; D. A. Jackson, Proc.Roy. SOC., 1934,143, [A], 455; A. B. McLay and M. F. Crawford, Physical Rev., 1933, [ii], 44,986; H. Kopfermann and E. Rindall, 2. Physik, 1934, 87, 460; A,, 339;F. Paschen and I. 8. Campbell, Naturwiss., 1934, 28, 136; A., 467; J. Joffe,Physical Rev., 1934,.[ii], 45, 468; A., 575; S. Tolansky, Nature, 1934, 133,531; A., 576; Proc. Roy. SOC., 1934,146, [A], 182; A., 1147; D. A. Jacksonand H. Kuhn, Nature, 1934,134, 25; A., 823; E. G. Jones, Proc. Roy. SOC.,1934, 144, [ A ] , 587; A., 823; 0. E. Anderson, Physical Rev., 1934, [ii], 45,685; A., 521; ibid., 46, 473; A., 1280.neutron __p proton + electron + neutrino.26 Ann. Reports, 1934, 30, 76THOMFSON : MISCELLANEOUS SUBJECTS. 85In view of the unsatisfactory state of the theory of nuclear structure:it is not surprising that the new values often found are not easilyexplained.General discussions of the subject have been given byE. Fermi and E. Segr&,28 by W. E. by H. Kallmann andH. SchiilerY30 by G. GamowY3l and others (see also this vol., p. 372).The most significant measurements in this field relate to thosestructures which might prove to be elementary particles in the pro-cess of atom-building, oix., the proton, deuton, and neutron; theelectron-spin moment has long been taken as Q Bohr unit in order tofit spectral requirements. Details of these measurements are fullyreported elsewhere (p. 372).Consideration of the law of conservation of angular momentum innuclear disintegration processes may also be used to determinenuclear-spin moments.In this manner H. Raether 32 estimatesthe neutron mechanical moment to be 8 Bohr nuclear unit. D. R.Inglis and A. Land&,33 assuming values of magnetic moments ofhigher nuclei, in this way find that the magnetic moment of theprotcrn should bc 2, the spin moment of the neutron i, and themagnetic moment of the neutron - 0.6 unit. I. Tamm andR. Altschuler’s 34 value agrees with the latt’er, but H. Schiiler 35 ob-tains a different result.Tite Structure of Liquids.-The phenomenon of crystalline liquidsor “liquid crystals ” has long boen known. The belief that“ amorphous,” optically isotropic liquids also possess some spatialorderly arrangement has become prevalent only during the pastfew largely from measurements on the diffraction of X-raysby these liquids.This orderly structure has been called a‘‘ cybotactic ” condition; references to earlier work on the subjectare given in C. Drucker’s summarising article.37A variety of molecule types have now been studied, e.g., chainmolecules such as n-alcohols, n-fatty acids, n-paraffins, benzene andcyclohexane derivatives. The results lead to deductions of thediameter of carbon chains, distance between adjacent carbon atoms,28 Mena. R. Accd. d‘ItaEia Sci. jk., 1933, 4, 131 ; A., 231.29 Nature, 1934, 133, 256; A., 340.30 Z . Physik, 1934,8$, 210, 323; A., 580.31 Ibid., 89,592; A., 939; Nature, 1934,133,833; A., 715; Proc. Roy. Soc.,1934, 146, [ A ] , 217; A., 1152; see also K. Guggenheimer, J . Phys. Radium,1934,5, 475; A., 1284.32 Natuiwiss., 1934, 22, 151.34 Compt.rend. Acad. Sci. U.R.S.S., 1934, 1, 455; A., 680.35 2. Physik, 1934, 88, 323.36 G. W. Stewart, Chem. Reviews, 1929, 6, 483; Rev. Mod. Physics, 1930.2, 116; other references are given by H. K. Ward, J . Chem. Phylsics, 1931.2, 163.33 Physical Rev., 1934, 45, 542.37 Physikal. Z . , 1928, 29, 37386 GENERAL AND PHYSICAL CEEMISTRY.thickness of benzene rings, and of the occurrence of associatedmolecules in solution. As an instrument for investigating the natureof different types of electrolytic solution, the method promises to beof some importance.G. W. Stewart88 has studied the case of concentrated solutionsof lithium chloride in ethyl, propyl, and butyl alcohols. It appearsthat in these solutions both lithium and chlorine ions participatewith the molecules of the solvent in forming a common liquidcybotactic structure, and also that the solutions are really solutionsof the alcoholates of the lithium chloride above the correspondingtransition temperatures.The temporary cybotactic structures canbe regarded as similar t o ionic crystals, conduction in which hasdefinite similarities to conduction in electrolytes.Stewart39 has also applied the method t o the analysis of waterand of deuterium oxide. The results are discussed in connexionwith the ideas of J. D. Bernal and R. H. Fowler4(’ on the liquidstructure of water. N. S. Guigrich and B. G. Warren 41 have showntheoretically that existing calculations for the intensity of X-raysdiffracted by a fluid a t various densities should only be applied overa small range of density.Comparison is made with the experimentalresults of Stewart42 with ether. W. Kast43 has compared theX-ray diagrams given by the isotropic and anisotropic melt ofp-azoxyanisole. There is no appreciable difference, from whichit is concluded that in both cases groups of oriented molecules existwith approximately the same molecular aggregation. R. D.Spangler 44 has attempted to follow with ether the change from acybotactic state to the random arrangement of a gas as conditionsof pressure and temperature are altered.Optical Activity.-According to the original theory of Pasteur,optical activity of a, molecule appears when the structure is sounsymmetrical that it cannot be superposed upon its mirror image ;one enantiomorph is dextro-, the other lsevo-rotatory.The questionof the “absolute” configuration, i.e., which of the two mirrorimages is dextro- and which laevo-rotatory, is not discussed. Solong as no hypotheses regarding the origin of optical rotatory powerwere available, the question was not answerable. With the intro-duction of some theory which can explain the reasons for the powerof optical rotation, it might be possible to assign the individual‘‘ absolute ” configurations of the enantiomorphs.30 J . Chern. Physics, 1934,2, 147; A., 591.40 Ibid., 1933,1, 515; A., 1934, 13; Ann. Reports, 1933,30, 34.l 1 Physical Rev., 1934,46,248.4R Naturwi38., 1933,21, 737; Ann.Phy&k, 1934, [v], 19, 571; A., 478.’I1 Physical Rev., 1934, [ii], 46, 698; A,, 1297.as Ibid., p. 558.Tram. Paraday Soc., 1933, 29, 982THOMPSON : MISCELLANEOUS SUBJE13TS. 87W. Kuhn and K. Beiii45 have made a valuable contribution t othis subject. By means of models, the optically active behaviourof compounds of the type of pentaerythritoldipyruvic acid,potassium cobalt oxalate, K3[Co(C204)3], and the compound[Co en,]Br3, (en = ethylenediamine), in absorption bands in thenear ultra-violet and visible region has been calculated. Thefundamental assumption is that the coupling forces which areeffective between the various parts of the molecule in opticaloscillations can be deduced, at least as far as sign is concerned,from the polarisability of the various parts of the molecule and thevibrational scattering moments in the adjoining parts. This affordsa semi-quantitative explanation of the observed behaviour of thepotassium cobalt oxalate complex.Relations are deduced permit-ting the calculation of the anisotropy factor of an absorption bandhaving a scattering moment of any form. With asymmetriccompounds the optical activity of which is due t o unsymmetricalarrangement of like symmetrical parts, the absorption bands areresolved into parts the anisotropy factors of which for a given banddiffer in magnitude and at times in sign. This has been detectedwith the two absorption regions of the double oxalate in the visibleregion, and from a comparison of the optical properties of this com-pound with those of a model, it has been possible t o deduce the ab-solute configuration of the isomeride which is bvorotatory in sodiumD light (and dextrorotatory in red light). The conclusions areconfirmed by measurements of the absorption, rotation, and circulardichroism in the range 2600-9000 8.Valency and the Structure of Molecules.-In continuation of mattersreported upon last year, several papers have dealt with the electronicstructure of molecules by the methods of quantum mechanics.M.lMarkov46 has considered the benzene molecule as composed ofsix tervalent nitrogen-like CH groups, and by applying theHeitler-London-Rumer theory of valency, has investigated themechanical and thermodynamical stability of the structure. IT.G.Penney 47 has examined the energy of (CH), structures in general,and concludes that C6H6 is the most stable, is slightly buckled, andshould be easily hydrogenated. In discussing the structure ofhydrogen peroxide and of hydrazine, W. G. Penney and G. B. B. M.Sutherland 4* have concluded that the large dielectric moments of46 2. physikal. Chem., 1934, 54, [B], 335; A., 476; Ber., 1933, 66, 166;413 J. Chm. Physics, 1933, 1, 784; A., 1934, 133.47 Proo. Roy. SOC., 1934, 148, [A], 223; A . , 1158.4.9 Trans. Faraday SOC., 1934, 30, 898; -4., 1158; J. Chem. Physics, 193-1,see also 5. F. Boys, Proc. Roy. SOC., 1934, 144, [A], 655, 675; A., 832.2, 492; A., 115888 GENERAL AND PHYSICAL CHEMISTRY.these compounds are due to an unsymmetrical form and not to freerotation.W. G. Penney49 has shown that in ethylene all sixnuclei should be coplanar, and in ethane only the H-H repulsionprevents free rotation of the methyl groups about the C-C axis.J. H. van Vleck 50 has discussed the electronic states of the carbonatom with special reference to the structure of methane. Accordingt o this author, the W state of carbon probably lies 7 volts above theground state. The method of the Hartree self-consistent field hasbeen applied to Kf, Cs+, and C.51 The molecule Li, has been studiedwave-mechanically.62 R. S. Mulliken 53 has attempted to constructan (‘ absolute ” scale of electronegativity for the elements by takingthe average of ionisation potential and electron affhity. The electro-affinity of an atom has different values for different values of itsvalency, in general being higher for higher valencies.The scalecalculated for many elements agrees well with that of Paulingbased on thermal data. L. Pauling and G. W. Wheland, and L.Pauling and J. Sherman, have applied the idea of resonance betweenlinks in molecules to the determination of the structure of benzeneand naphthalene. These matters are discussed on p. 37. N. V.Sidgwick and R. W. Bailey * have drawn some interesting correl-ations between the strwtures of carbonyls and nitrosyls. Thethree-electron bond has been discussed in connexion with potassiumsuperoxide. 64Several papers relate to the theory of ‘( normal ” vibrations ofpolyatomic molecules.55 In connexion with the empirical analysisof the energy levels of isoolectronic diatomic molecules, the study ofthe 22-electron molecule PN is of interest.56 The data for thismolecule are similar to those of the isoelectronic SiO and CS, andare intermediate between the 14-electronic N, and CO and 30-electronic Pz molecules in all important features.Proc.Roy. Soc., 1934, 144, [A], 166; A., 476.50 J . Chern. Physics, 1933, 1, 177, 219; A., 13; ibid., 1934, 2, 20, 297;A., 241, 719.61 D. R. Hartree, Proc. Roy. SOC., 1934, 143, [A], 506; A., 344; PhysicalRev., 1934, [ii], 46, 738; A., 1285; C. C. Torrance, ibid., p. 388; -4, 1153;cf. Ann. Reports, 1933, 30, 62.52, E. B. Wilson, J . Chem. Physics, 1933,1, 210; A., 1934, 1 ; H. M. James,ibid., 1934, 2, 794.63 Ibid., p.782.63a Proc. Roy. SOC., 1934, [A], 144, 521 ; A., 833.54 E. W. Neuman, J. Chem. Physics, 1934, 2, 31; A,, 242.6 5 See, e.g., E. B. Wilson, Physical Rev., 1934, [ii], 45, 706; A., 829; A.Eucken and H. Ahrens, 2. physikal. Chern., 1934, [B], 26, 297 ; A , , 1055.66 J. Curry, L. Herzberg, and G. Herzberg, Ann. Physik, 1934, [v], 20,569 ;A., 1153; J , Chern. Physics, 1933, 1, 749; A , , 1934, 7 ; 2. Physik, 1933, 86,348; A., 1934, 7; see also W. Jevons, Nature, 1934,133, 619; A., 581THOMPSON : MISCELLANEOUS SUBJECTS. 89The electronic theory of valency has been criticised and theoriesof valency in general discussed by R. Samuel and 0thers.~6a Theseauthors believe that valency is always covalency and may vary inpolarisability from zero to that of a true salt.They do not admitthe existence of co-ordinate links in such molecules as carbon dioxideor the complex cyanides. They point out that the inner (B2) groupof electrons usually considered responsible for co-ordinate valencyformation cannot enter into chemical union with other atoms untilsplit, i.e., until the atom containing this group is excited, and theydefine valency as the passage of electrons from each participatingatom into a closed group in the molecule. From a review ofspectroscopic and thermochemical data R. Samuel and H. Less-heim s6* conclude that many molecules are produced by union ofatoms in anomalous states of excitation. In the case of carbondioxide the necessary state of the carbon atom is thought to be p4,Le., not s2p2 or sp3.Carbon monoxide, arising from the s2p2 con-figuration, in which only two p electrons will be used, is regardeda8 involving a bivalent link. It is impossible to enter into furtherdetails of this subject. Many differences of opinion expressed areultimately attributable to differences in definition and certain ofthe linkage energies deduce4 may be inaccurate. R. S. Mulliken 5 6 ~also has discussed the structure of carbon monoxide.An ingenious experiment has been made by J. N. E. Day, E. D.Hughes, C. K. Ingold, and C. L. Wilson 57 in which the differencein properties of water and heavy water was used in investigatingthe structure of salt hydrates. It has been commonly supposedthat cationic hydration occurs by means of a metahxygen co-ordinate link (I), whereas anionic hydration involves co-ordinationwith the hydrogens of the water molecule (11).The alternative theory of Fajans, Born, and others regards thehydrate more as a physical cohesion of dipoles.If the co-ordinationtheory applies, the nature of the hydrogen atoms in the watermolecule should not much affect cationic hydration, but withanionic hydrate there will be a preferential hydration between lightand heavy water. The experiments aim a t detecting this effect,but the results cannot be regarded as conclusive. If any inferences660 R. F. Hunter and R. SAmuel, J., 1934, 1180; A., 1058; H. LeseheimandR. Samuel, 2. Physik, 1933, 84, 637; Current Sci., 1933, 374; R. Samueland M. J. Kahn, 2. Physik, 1933, 84, 87.4.b Proc. Physical SOC., 1934, 46, 623; A., 945.6QS J .Chem. Physics, 1934, 2, 400; A., 942.6 7 J . , 1934, 1593; A., 130390 GENERAL AND PHYS1Wi.L CHEMISTRY.can be drawn from them, it would be that the physical theory ofhydration is supported, the linkings of the hydrate having a veryloose nature.Supersonic Waves.-The rapid degradation of intensity sufferedby compressional waves of high frequency when passing throughgases, was first observed by W. C. Pierce 58 in carbon dioxide. Thedetermination of the velocity of such supersonic waves, producedfrom piezoelectric quartz oscillators, and their dispersion by gasesin general, has received considerable attention in recent years.59This dispersion may be ascribed to one or more of three causes :(a) there may be a lag in the transfer of energy between one andanother of the degrees of freedom of the molecule, (b) selective orresonant absorption may occur, (c) there may be an abnormalviscosity under the high-frequency vibration.It is perhaps by virtue of the factor (u) that this subject is ofinterest and importance to those concerned with chemical kinetics.60The theory of the propagation of sound waves in a gas, with specialreference to the intramolecular energy transfers, has been examinedrecently by several workers.61 Long ago, (Sir) J. H. Jeans 6% showedthat in a gas in which there was a delay in the passage of trans-lational energy into vibrational energy, the velocity of soundwould be higher than normal, owing to the enhanced ratio of thespecific heats, if the source of sound had a period comparablewith the (‘ time of relaxation.” This would involve a diminishingamplitude of the waves. When the period of oscillation approachesthe relaxation time, there should be a rapid rise in the velocity ofpropagation.has examined the dispersion of supersonicwaves in oxygen, carbon dioxide, nitrous oxide, sulphur dioxide, andargon. His results as a whole substantiate the Jeans relaxation-time theory, i.e., cause (a), but there may be some indications ofselective resonant absorption a t frequencies considerably lowerthan those hitherto considered possible. It is interesting to observe58 Proc. Amer. Acad. Sci., 1928, 43, 375.59 For a general account, see J. Hubbard, J . Acoust. Soc., 1932, 4, 99;also W. H. Pielemeier, Physhzl Rev., 1929, 34, 1184; 1930, 36, 1005; 1931,38, 1236; 1932, 41, 833; T. P. Abello, Phy8kal Rev., 1928, 31, 1083; A.,1928, 828; H. Ifneser, Ann. Physik, 1931, 11, 761, 777; 2. Physik, 1932, 77,649; E. Grossmann, Ann. Physik, 1932,13, 681.E. G. Richardson60 Cf. Ann. Reports, 1933, 30, 39.61 K. F. Herzfeld and 0. K. Rice, Physical Rev., 1928,31, 691 ; A. Bourgin,Phil. Mag., 1929, 7 , 821; H. Kneser, Ann. Phy8ik, 1931, 11, 761; W. T.Richards, J . Chem. Physics, 1933, 1, 863, 879; A., 1934, 136.62 “ Dynamicd Theory of Gases,” p. 320 (1904).e3 Proc. Roy. Soc., 1934, 146, [A], 66; A., 1164THOlYDPSON : MISCELLBNEOUS SUBJEOTS. 91that in some cases there was a marked scattering of the radiantenergy, an effect, moreover, which was most pronounced withstrongly anisotropic molecules which show the Raman effectmost readily.H. H. Rogers 64 has made similar measurements on the absorptionof supersonic waves in mixtures of air and carbon dioxide containingdifferent amounts of water vapour.W. T. Richards and J. A. Reid,65 in very detailed papers, havegone further by attempting to discover how the translationalenergy of the sound wave is selectively transformed into vibrationalenergy of different types (symmetric or deformation vibrations,S+C+S, S\l.C+SJ.) in the molecules carbon dioxide, carbon di-sulphide, and sulphur dioxide. They have also measured thevelocity of sound in ethylene at various pressures, temperatures, andfrequencies, and conclude that with this substance equilibrium isattained between the various states of vibrational energy in everyeffective collision, but that considerable activation energy of collisionis required for the conversion of translational into vibrationalenergy. Collisions with argon, helium, or nitrogen molecules haveno appreciable effect on the vibrational energy of the ethylenemolecule. Collisions with hydrogen are about ten times as effectiveas et hylene-ethylene collisions in producing transitions in thelower vibrational energy states of ethylene. It is peculiar thatethylene-hydrogen mixtures appear to be about twenty times aseffective as hydrogen-hydrogen collisions in exciting the rotationalenergy of hydrogen molecules.5. Franck and A. Eucken 66 also have studied the conversion oftranslational kinetic energy into inttmal energy of vibration, andattempt to consider the problem from the standpoint of the L c ex-change ” forces opsrative between the colliding partners ratherthan by classical methods involving laws of impact. From measure-ments on the dispersion of supersonic waves by chlorine and carbondioxide, A. Eucken and R. Becker 67 have found that the transferof energy of translation to intramolecular vibrations is in thesecases favoured by the addition of inert gases.Some similar experiments have been made with liquids.68Optical Phenomenu and Energy Transfers.-In addition to theforegoing, a series of optical considerations promises to clarify themechanism of inter- and intra-molecular transfers of energy. The64 Physical Rev., 1934, [ii], 45, 208; A., 354.6 5 J . Chem. Physics, 1933,1, 737; A., 19; 1934,2, 193, 206; A., 588.6 6 2. physikal. Chem., 1933, [B]. u), 460; A., 1933, 554.6 7 Ibid., p. 467; ibid., 1934, [B], 27, 219, 235.68 J. C. Swansen, J . Chern. PhyaicS, 1934,2, 68992 GENERAL AND PHYSICAL CHEMISTRY.quenching of fluorescence by added inert gases has already beenmuch studied, and further data are now reported.69 In manycases specific properties seem to be involved, and the whole subjectis far from clearly understood.The quenching of inert gases of a different type of emissionspectrum, however, appears to offer important data. It is possiblefrom an analysis of the distribution of intensity in the rotationallines of a band in a molecular spectrum to determine the temper-ature of the emitting rn~lecule.~O Measurements of this kind onspectra emitted from discharge tubes have frequently revealedtemperatures of some thousands of degrees, far higher than seems~lausible.~l 0. Oldenberg 72 has discussed the interpretation of thisresult. When a polyatomic molecule is broken into fragments bysome process such as takes place in a discharge tube, it is notdifficult to understand how the fragments may fly apart each in arapid state of rotation. Thus, if in the disrupture of the triangularwater molecule one 0-H bond is broken under extension, thehydroxyl radical liberated will possess surplus energy of rotation.The intensity distribution in the bands of hydroxyl formed in adischarge tube containing water vapour do, in fact, show “ abnormalrotation.” Oldenberg has found, however, that the addition ofsmall quantities of helium removes the excess rotational energy so asto produce a normal temperature distribution ; this gas is, moreover,specifically fitted for the purpose.I n the same way, the bands of HgH formed in the sensitisedfluorescence of hydrogen by mercury have indicated a temperatureof 3000” H. Beutler and E. Rabinowitsch 74 concluded thatthis was due to ‘( abnormal rotation ” ; the peculiarity is thatnitrogen does not reduce the apparent temperature, and the surplusenergy must be retained over many collisions.0. S. Duffendack, R. W. Revans, and A. S. Roy 75 have also shownthat added helium alters the distribution of intensities in the rotationlines in the bands of the N,+ spectrum. The question arises as to6D See, e.g., J. F. Koehler, Physical Rev., 1933, [ii], 4, 761; A., 2; N. A.Prileshaeva, Compt. rend. Acad. Sci. U.R.S.S., 1933, 282; A., 1934, 340;0. S. Duffendack and J. S. Owens, Physical Rev., 1934, [ii], 46,417; A., 1148;M. G. Evans, J . Chem. Physics, 1934, 2, 445; K. Weber and M. L. Savib,2. physikal. Chem., 1934, [B], 24, 68.70 L. S. Ornstein and W. R. van Wijk, 2. Physik, 1928, 49, 315; A,, 1928,930; W. Lochte-Eoltgreven, ibi&., 1930, 64, 443; 1931, 67, 690.7 1 Idem, W.; 0. Oldenberg, Physical Rev., 1931, 37, 1550; N. Thompson,Proc. Phy&l Soc., 1934,46, 436; A,, 711.72 Phy&id Rev., 1934, [ii], 46, 210; A., 1153.73 R. W. Wood and E. Gaviola, Phil. Mag., 1928, 6, 1191.i4 2. phyaikal. Chem., 1930, [B], 8, 403.7 5 Physicccl Rev., 1934, [ii], 45, 807; A., 823THOMPSON : MISCEIJX”0US SUBJECTS. 93whether ‘‘ abnormal vibration ” is similarly possible. The examplesgiven may, however, serve to indicate the nature of the work.The effect of inert gases on the absorption spectra of polyatomicmolecules has also been studied.’g This may prove to be afruitful field of investigation. Hi W. T.It. P. BELL.E. J. BOWEN.N. V. SIDGWICK.H. W. THOMPSON.L. A. WOODWARD.i 6 H. I. Agarbiceanu, Ccnnpt. rend., 1933, 197, 1198; A., 1934, 2; P. C.Cross and F. Daniels, J . C h . P h y h , 1934, 2, 6; A., 238

ISSN:0365-6217    

DOI:10.1039/AR9343100013

出版商:RSC    

年代:1934

数据来源: RSC

摘要:

INORGANIC CHEMISTRY.1. ATOMIC WEIQHTS.THE separation from each other, by chemical means, of the scarcermembers of the rare-earth group of elements is attended by so manydifficulties that the finality of the values assigned to their atomicweights may well be questioned. For these elements, especially,the advantages of a control by physical methods are obvious, butsince the examination in 1925,l of lanthanum, praseodymium,cerium, and neodymium in the first mass spectrograph, no data havebeen available until this year. F. W. Aston has now succeeded inso improving the original method of accelerated anode rays, thathe has been able to obtain with this series of elements the requisiteintensity in the high-resolution mass spectrograph, and to determinethe isotopic constitution and atomic weights of the remaining tenelements.Considering the whole group of fourteen elements of atomicnumbers 57 to 60 and 62 to 71, the elements of odd atomic numbers,wiz., La (57), Pr (59), Eu (63), Tb (65), Ho (67), Tm (69), Lu (71), allprove to be simple with the exception of europium, which consistsof a nearly equal mixture of the isotopes 151 and 153.Of the evenelements, samarium (62) was found to be the most complex, and toconsist of seven isotopes. Neodymium, gadolinium, and ytterbiumcontain six isotopes each, and erbium and dysprosium four each.The mass-spectrum values for the atomic weights agree closelywith the international values for La, Ce, Pry Eu, Dy, Yb, and Lu,but are smaller than the chemical values in the other seven cases.These discrepancies are discussed in another part of this v01ume.~Since terbium and thulium are simple elements and the twin linesof europium are well defined and easy to measure, the chemicalvalues are almost certainly in error.I n the same paper, Aston calls attention to the case of osmium,for which he obtained the value of 190.31 in 1931, which was dis-tinctly lower than the then-accepted chemical value 190.9, but veryconsiderably lower than the new value of 191.5 adopted by theInternational Committee in their last report.* It will be interestingF.W. Aston, Phil. Mag., 1925, 49, 1191.PTOC. Roy. Soc., 1934, [A], 146, 46; A., 1150.J., 1934, 499.a P. 370.F. W. Aston, Proc. Roy. Soc., 1931, [A], 132, 487WHYTLAW-GRAY : ATOMIC WEIGHTS.95to see whether further work on the chemical side confirms the higherfigure, but up to the present, with the exception of tellurium,revision of the chemical atomic weights has invariably supportedthe results obtained with the mass spectrograph.The redetermination of the atomic weights of niobium andtantalum by 0. Honigschmid is another example of this, and hascleared up the discrepancy noticed in last year’s report.’ Tantalumbromide and niobium chloride were prepared in a high state ofpurity and, after vacuum sublimation, were weighed. They werethen brought into solution, and the silver equivalent determined bystandard procedure. The values obtained were Ta = 180.89, Nb =92.91, in close agreement with Ta = 180.89, Nb = 92.90 found byAstonY8 but very appreciably lower than the International values,181.84 and 93.3 respectively.A detailed account of this work onniobium has been published by 0. Honigschmid and K. Winters-berger.g Other investigations published recently which confirmAston’s values are those on the atomic weight of molybdenum by theanalysis and synthesis of its trioxide by R. Lauti6,lo which gave thevalue Mo = 96.01; and on the densities and atomic weights ofkrypton l1 and xenon by W. Heuse and J. Otto.12 The latter worksupports the value obtained previously for these two gases byH. E. Watson,13 and by R. Whytlaw-Gray, H. S. Patterson, andW. Cawood l4 by microbalance methods.Turning now to work along classical lines, there is not much toreport since last year, but mention should be made of an importantinvestigation by C.R. Johnson15 on the atomic mass of sodium,in which a very careful and critical study was made of the errorsinherent in the measurement of the ratios NaCl : Ag and NaCl : AgClby standard methods. Special attention was paid in this researchto accurate nephelometry and to the determination of the correctend-point both in titration and in the estimations of the washings.A potentiometric method was used in some cases to control theresults of the nephelometer. Among the many points of detailstudied may be mentioned the neutrality of the fused sodiumchloride, adsorption and solubility of silver chloride, the presenceof films of silver chloride or silver on the vessels used, and of invisiblecracks in the Pyrex flasks and beakers which might have retainedNaturwiss., 1934, 22, 463; A., 937.2.anorg. Chem., 1934,219, 161.Ann. Reports, 1933, 30, 1.* J., 1932, 2888; Nature, 1932,130, 130.10 Compt. rend., 1933,197, 1730; A., 127.11 Physikal. Z., 1934, 35, 67; A., 234.l2 Ibid., p. 628; A., 1053.14 Proc. Roy. SOC., 1931, [A], 134, 7; A,, 1932, 106.l5 J . Phyaicd Chem., 1933, 37, 923; A., 1934, 4; -also A., 1933, 773.l3 Nature, 1931, 127, 631 ; A,, 66696 INORGANIC CHEMISTRY.traces of liquids. The result of six closely concordant experimentsgave NaCl : Ag = 0.541817, and that of five gave the gravimetricratio NaCl : AgCl = 0.40779. From each of these, by taking Ag =1074380 and C1= 35.457, the same value Na = 22.994 was obtained :a value slightly lower than the international figure, Na = 22.997.G.P. Baxter and A. H. Hale16 have determined the ratio1205:Na2C0,. This is the first time since the work of T. W.Richards and C. R. Hoover,17 who measured the ratio Na2C03:NaBr: Ag, that the atomic weight of carbon has been linked upwith the silver standard. Richards and Hoover’s ratios wereunfavourable for the calculation of an accurate value for carbon,giving values ranging from 11.997 to 12.008. Baxter and Halesfound, as the mean of nine closely concordant experiments,I,O, : Na2C0, = 3.14950, but unless the atomic weights of iodineand sodium are known to a very high degree of accuracy, that ofcarbon remains uncertain. If, for inatance, we use the internationalvalues Na = 22.997 and I = 126.92, carbon becomes 12.005, butwith Na = 22.994 and the same value for iodine, C = 12-010.Thelatest value for iodine is 126.917, determined by Honigschmid andH. Striebe1,f” which agrees closely with the mass-spectrographvalue of 126-91, but really, at the present time, the accuracy ofexperiment is insufficient to discriminate between these smalldifferences.Evidence of a more direct character supports the new and highvalue for carbon advanced by M. Woodhead and R. Whytlaw-Gray lBin 1933. It will be remembered that these workers obtainedC = 12.011 by a comparison of the limiting densities of carbonmonoxide and oxygen with a microbalance, a value perceptiblygreater than C = 12.007 found for the same ratio by E.Moles andM. T. Salazar 2O using the standard methods of comparing gas densi-ties. The last two workers21 have now published a new series ofmeasurements of the densities of these two gases by an improvedmethod, which gives as the atomic weight of carbon 12.0065. Inthe meantime, F. W. Aston 22 has compared photometrically thesecond-order lines at positions 6 and 6.5 of C12 and C13 and hasfound the isotopic ratio to be C12 : C13 = 140 : 1, whence, allowancebeing made for the packing fraction and change of scale, the atomicweight of carbon = 12*0080. It may be mentioned thatl6 J . Amer. Chem. SOC., 1934, 56, 615; A., 469.l7 Xd., 1915, 87, 95; A., 1915, ii, 96.l8 Z. anorg. Chem., 1932,208,53; 2. physikal. CJwm., Bodenatein Festband,l9 J ., 1933, 846; A., 1933, 894.2o Anal. Fis. Quim., 1929, 27, 267; A., 1931, 407.* l Ibid., 1934 82, 054.1931, 282; A., 1931, 1208.az Nature, 1934, 184, 178; A., 937WHYTLAW-GRAY : ATOMIC WEIGHTS. 97F. A. Jenkins and L. S. Ornstein 23 found by a study of the bands ofthe Swan spectrum the ratio C12 : C13 = 106 : 1, which has beenconfirmed by the work of J. P. Tate, P. T. Smith, and A. L.Vaughan,% who found C13 present to the extent of 1%, which sup-ports the higher value C = 12.011 although it is difficult to assessthe probable error in these figures, There now seems, however,to be no reasonable doubt that the true chemical atomic weight ofcarbon lies close to 12.01 and that the international value of 12.00is too low.Just recently, important new evidence has appearedwhich supports the high value. H. S. Patterson and W. C a ~ o o d , ~ ~using an improved microbalance technique, have compared the limit-ing densities of carbon dioxide, ethylene, nitrous oxide, carbontetrafluoride, and oxygen and repeated part of their earlier work onmethyl fluoride. The final results are : N = 14.007, C = 12.012(from ethylene), C = 12.010 (from CO,), F = 18.995 (from CF,),and P = 18.995 (from CH,F).As a check on the method, the compressibilities of the gases weremeasured by means of an Andrews apparatus, as well as by themicrobalance, and a good agreement obtained. The two valuesfor fluorine agree very closely with F. W. Aston’s value 26 of 18.996,and negative definitely the possibility of the existence of a higherisotope.The value for nitrogen is rather lower than 14.008, theaccepted figure, and also than the recently published values ofE. Moles and J. Sancho 27 from ammonia, N = 14.008, and of Molesand Salazar 21 from nitrogen itself, N = 14.0083. A full accountof the work of Patterson and Cawood will appear shortly, but itmay be stated that it has been carried out with every modernrefinement and attention to detail.The discovery that hydrogen is a mixed element and that the iso-topes are easily separable has cast doubt on the accuracy of one ofthe fundamental atomic-weight ratios, viz., that of 0 : H. Thenumerous determinations made of the atomic weight of hydrogenwere summarised by E. Moles 28 in 1925, and the final mean calculatedfrom the results of five different workers was found to be 1.00777.Inall cases, the hydrogen was prepared by electrolysis of either acid oralkaline solutions, and usually was weighed on palladium. It isprobable then that this hydrogen was deficient in the heavier isotopeand that the mean atomic weight is too low. It seems unlikely thathydrogen of normal isotopic content was ever used in measuring23 Proc. K . Akad. Wetensch. Amsterdam, 1932, 35, 1212; A., 1933, 333.24 Physical Rev., 1933, [ii], 43, 1054.25 Nature, 1935, in the press.26 “ Maas Spectre and Iaotopos,” p. 150; PYOC. Roy. Soc., 1927, [A], 115,487.2 7 Anal. Pis. Quirn., 1934, 82, 931. 2. physikal. Chem., 1925, 115, 61.REP.-VOL. XXXI. 98 INORGANIC CHEMISTRY.this ratio, though the oxygen employed probably contained itsisotopes in the usual proportions.Now the ratio of the masses of 0l6 and H1 has been determinedwith great exactness with the mass spectrograph by F.W. Aston 29and by E. K. Bainbridge 30 and found to be 16.0000 : 1.00778.The mean mass number of chemical oxygen on the physical scalecan be calculated if the proportion of the heavier isotopes is known.This has been determined spectroscopically by a number of differ-ent observers, who obtain values varying from 0 l 8 : Of6 = 1 : 1250 31to 1 : 630,32 the proportion of 017 being negligible. Of these,the second ratio is generally regarded as the most probable, andgives a value of 16.0035 for the atomic weight of chemical oxygenon the physical scale.Hence pure H1 or protium has an atomicweight on the chemical scale of 1.00778 x 16.0000/16.0035 =1.00756. If, now, we know the proportions of the two hydrogenisotopes present normally in the element, we can calculate the atomicweight. Unfortunately, the data on this point are not very con-cordant. The earlier spectroscopic estimates of W. B l e a k n e ~ , ~ ~of H. Kallmann and W. LasareffF4 and of J. T. Tate and P. T.Smith 35 were too low and gave values for D : H of 1 : 30,000 to1 : 40,000. G. N. Lewis 36 and R. T. Macdonald?' from their ex-periments on the electrolytic preparation of heavy water, calculate1 : 6500. W. Bleakney and A. J. Gould 38 have recently redeter-mined the ratio spectroscopically, using hydrogen from rain water,which was decomposed completely by passage over heated iron;they found the value 1 : 5000.They also investigated the isotopicratio in hydrogen from freshly prepared electrolytic cells and foundit t o be about 1 : 25,000. A value distinctly lower than the lastthree has been found by (Mrs.) E. H. Ingold, C. K. Ingold, H.Whitaker, and R. Wh~tlaw-Gray,~~ who, by the action of metalson water and by electrolysis, have prepared specimens of watercontaining a low proportion of deuterium and have comparedtheir densities with that of standard water by using a delicate floatmethod. The value given in a preliminary notice is 1 : 9000.2B op. cit., p. 100. 30 Physical Rev., 1933, 43, 103 ; A., 1933, 203.31 H. D. Babcock, ibid., 1929, 34, 640; A., 1929, 971; 1930, 1232.32 R.Mecke and W. H. J. Childs, 2. Physik, 1931, 68, 362; A., 1931, 543;see also S . M. Naudd, Physical Rev., 1930, 36, 333; H. M. Kallmann and W.Lasamff, 2. Physik, 1933, 80, 237; A., 1933, 333; R. T. Birge and D. H.Menzel, Physical Rev., 1931, [ii], 37, 1669; A., 1933, 204; F. W. Aston,Nature, 1932,130, 21.33 Physical Rev., 1932, 41, 32.35 Physical Rev., 1933, 43, 672.37 J . Ckem. Physics, 1933,1, 341.38 Physicctl Rev., 1933, 44, 265; A., 1933, 994.34 Naturwiss., 1932, 20, 206.36 J . Amer. Chem. SOC., 1933, 55, 1297.3B Nature, 1934,134, 661WARDLAW : METALUC CARBONYL AND NITROSYL COMPOONDS. 99If, now, we calculate the atomic weight of hydrogen on thechemical scale, using the two extreme values for the isotopic ratio,viz., D : H = 1 : 5000 and 1 : 9000, we get respectively 1.00776 and1.00767, both of which are smaller than the mean value found bychemical methods, vix., 1.00777, which should itself be less than thetrue value.H.Muckenthaler,*o in an interesting paper, has fully discussedthis discrepancy, and contends that it is to be explained by the useof an erroneous value for the isotopic ratio in oxygen. He hasredetermined this ratio, using (Sir) J. J. Thompson's parabolamethod, and finds 0 l 8 : 0l6 = 1 : 1058, which lies nearer to theearly value of Babcock than to that of Mecke and Childs. It may benoted, however, that, even if we assume Babcock's value for theoxygen ratio, and that of Bleakney and Gould for the proportionof the hydrogen isotopes, the value for hydrogen is only raised to1.00787, which exceeds the mean chemical value by only 1 part in10,000.It is evident, then, that there is an unexpla'ined discrep-ancy between the chemical and the physical value for the atomicweight of hydrogen, and that further work on the chemical side isdesirable. R. W.-G.2. METALLIC CARBONYL AND NITROSYL COMPOUNDS.A particularly interesting chapter in inorganic chemistry dealswith the metallic carbonyl and nitrosyl compounds. Notableadvances have been made in our knowledge of these compoundsduring recent years through the numerous investigations of W.Hieber and W. Manchot and their collaborators. At the presenttime, amongst the simple carbonyls of the transition elements, fivemonometallic derivatives are known : Cr(CO),, Fe(CO),, Ni(CO),,Mo(CO),, W(CO),.In 1921, I. Langmuir 1 suggested that the volatilecarbonyls represent a type in which the metal atom takes on thenumber of electrons necessary to rcach the atomic number of thenext inert gas, nickel adding eight in Ni(CO),, iron ten in Fe(CO)5,and molybdenum twelve in Mo(CO),. This implies that eachcarbon monoxide molecule contributes two electrons to the centralmetallic atom. It will be noted that this principle applies equallywell to the more recently prepared carbonyls of chromium andtungsten.3 Moreover, it indicates why monometallic carbonyls40 Physikal. Z., 1934, 35, 851; A., 1283.1 Science, 1921, 54, 65; A., 1922, ii, 137.a A. Job and A. Cassal, Compt.rend., 1926,183,392; A., 1926, 1017; Bull.SOC. chirn., 1927, 41, 1041; M. M. Windsor and A. A. Blanchard, J. Amer.Chem. SOC., 1934, 56, 823; A., 589.3 A. Job and J. Rouvillois, Cowapt. Tend., 1928, 187, 664; A., 1928, 1201100 INORGANIC OHEMISTRY.are not formed by elements of odd atomic number such as cobalt(at. no, 27). It is well known that cobalt carbonyls show a greattendency to polymerise, so that the tetracarbonyl is really C O , ( C O ) ~ , ~whilst the tricarbonyl gives a molecular weight in Fe(CO), whichindicates the complexity CO,(CO),,.~Recent work has fully established that the carbon monoxidemolecule can be substituted by other molecules, with the productionof new substances of great theoretical interest. For example, onesuch group may be substituted by a molecule of ammonia, pyridine(py), or alcohol, and two groups by chelate groups such as ethylenedi-amine (en) (I), the diethyl ether of dithioglycol (th) (11), or o-phen-anthroline (phen) (111).In this way such substances are produced asCH2-NH241M H2F/ SEt ‘1M <*, H,C\ f Nh I CH,-NH2fSEt M(1.) (11.) (111.)Cr( CO),py,, Fe( GO),( NH,),, Ni( CO),phen, Fe2( CO),en,. It willbe seen that in all these cases the covalency of the metal is the sameas in the simple carbonyls from which they are derived. A secondseries arises by an alteration in the covalency of the metallic atom.The most remarkable examples of this type are iron carbonyl hydro-gen and cobalt carbonyl hydrogen and their derivatives. Thevolatile Fe(CO),H, 8 is an unstable yellow liquid (m.p. - 70’) formedby the action of alkalis on iron pentacarbonyl : Fe(CO), + 20H’ =Fe(CO),H, + (30,”. The extreme ease of oxidation of the CO-ordinately bound carbonyl group in alkaline medium is a distinctivefeature of the reaction. Methylene-blue is quantitatively reducedby Fe(CO),H,, and the active hydrogen may be determined in thisway, An outstanding property of this carbonyl hydride is theability fo form salts with organic bases such as pyridine and o-phenanthroline, whereby the stable compounds Fe( CO),H,, (C,H,N),and Fe(CO),H,,2C,,H,N2 are produced. The hydrogen in thelatter compound no longer reduces methylene-blue.In appropriate non-aqueous solvents, iron pentacarbonyl reacts4 L. Mond, H.Hirtz, and M. D. Cowap, J., 1910, 97, 798.W. Hieber, F. Muhlbauer, and E. A. Ehmann, Ber., 1932, 65, [B], 1090;A., 1932, 920.6 W. Hieber, Sitzungsber. Heidelberg. Akad. Wiss., 1929, 3, 4.‘7 W. Hieber and F. Sonnekalb, Ber., 1928, 61, 558; A., 1928, 510.W. Hieber and F. Leutert, Naturwiss., 1931, 19, 360; A,, 1931, 810; W.Hieber and H. Vetter, Ber., 1931, 64, [B], 2340; A., 1931, 1255; idem, 2.anorg. Chern., 1933, 212, 145; A., 1933, 686WARDLAW METALLIC CARBONYL AND NITROSYL COMPOUNDS. 101with halogens to give Fe(CO),X, where X = C1, Br, or I ; whilstwith mercuric sulphate in sulphuric acid solution, the pentacarb-onyl yields Fe(C0)4Hg.10 Other members of this series l1 whichare regarded as salts of Fe(C0)4H2 include Fe(C0),Na2, Fe(CO),Cd,[Fe(CO),H],,[Ni(NH,),], for dilute mineral acids liberate Fe(C0)4H2from them. Similar investigations with the other metallic carbonylsgave positive results only in the case of cobalt carbonyls.It hasbeen known for some time that the following reaction is realisable :2Co(CO),M + 2H' = CO" + Co(CO),H + 2CO + $H2 + M(M = alcohol or amine constituent.)Quite recently, however, E. A. Ehmann l2 has stated that if thereaction with CO(CO)~ is carried out in an aqueous solution ofalkali or baryta, a similar result is obtained to that with Fe(CO)5,but the mechanism is more complicated :3Co(CO), + 20H' = 2Co(CO),H + CO," + CO(CO)~ (polymerised).A part of the tetracarbonyl is decomposed simultaneously withliberation of carbon monoxide but without hydrogen evolution :3cO(Co), + 2H20 = 2Co(CO),H + Co(OH), + 4CO.The presence of Co(CO),H was proved by oxidation with hydrogenperoxide, as well as by titration with methylene-blue.Althoughthe isolation of such salts as [Co(CO),],[Ni(NH,),] and[Co(CO),],[Co(phen),] confirms the formula for the parent hydride,this has not yet been obtained. In chemical behaviour, the carb-onyl hydride of cobalt is distinguished from that of iron by itsmuch greater sensitivity ; e.q., spontaneous decomposition withformation of free carbonyl and free hydrogen occurs rapidly in acidsolution at the ordinary temperature. It is significant that, so far,no hydride of nickel carbonyl has been obtained, nor any saltderived from it. Examination of the following series shows thatthe E.A.N." of the metal is in each case that of the next inert gas :Fe ( CO ) 6, Fe ( CO ) ,H2 , Co ( CO ) 4H, Ni (CO ) 4.Lafstly, reference must be made to the interesting series of changesthat occur when the carbonyls react with nitric oxide.From thereaction of this gas and Fe(CO), dissolved in Fe(CO),, a red crystallinecompound Fe(CO),(NO), (m. p. 18.5") is obtained which decomposes9 W. Hieber and G. Bader, Ber., 1928, 61, [B], 1717; A,, 1928, 1202.10 H. HockandH. St;uhlmann, Ber., 1929,62, [B], 431,2690; A., 1929,412;11 F. Feigl and P. Krumholz, 2. anorg. Chem., 1933,215,242; A., 1934,159.12 See W. Hieber, 2. Ek&r&m., 1934,40, 168; A,, 611.* E.A.N. = effective atomic number, i.e., total number of electrons, sharedand unshared (see N.V. Sidgwick, " Electronic Theory of Valency," 1927,p. 163).1930, 47102 INORUmC CHEMISTRY.at 70°.13 Under appropriate conditions, this nitrosocarbonylreacts with iodine, pyridine, or o-phenanthroline to give Fe(NO),I,Fe2(NO)4(py)3, and Fe(N0);phen. l4 When iron pentacarbonyl isheated with nitric oxide under pressure, black crystals of irontetranitrosyl, Fe(N0)4, are obtained.14 Similar reactions are re-corded with cobalt carbonyls. Slowly a t room temperature,instantaneously at 40", nitric oxide reacts with Co(CO), to forma cherry-red liquid (b. p. 78.6") having the molecular formula,Co(CO),NO. With pyridine, this cobalt nitrosocarbonyl yieldsCo,(NO),CO,Bpy, and with o-phenanthroline, in benzene or methylalcohol, the complex substance CONO(CO),,C~,H,N,.~~ Otherresults of great interest have been omitted from this account,but sufficient has been recorded to indicate the substantial achieve-ments in this field of research.The constitution of the metallic carbonyl and nitrosyl compoundsis a fascinating but difficult problem.It cannot be said that a finaldecision has yet been reached, but an important paper by N. V.Sidgwick and R. W. Bailey l5 places the structures of these com-pounds on a much firmer basis. The experimental work alreadyreviewed shows that, in the carbonyls, a carbon monoxide groupoccupies one co-ordination position and thereby provides twoelectrons to form a link with the metallic atom. The carbonmonoxide molecule is obviously capable of co-ordinating througheither the carbon or the oxygen atom, but Sidgwick and Baileyconsider that it is more probable that the link is formed throughthe carbon, thus M+CO, since the 4-covalent condition is the normalstate of the carbon atom whereas it only rarely occurs with oxygen[e.g., in basic beryllium acetate, Be,0(CH3*CO-O),].They furtherstate that carbon monoxide is correctly formulated as :C;;zOz or%6. This formula, originally proposed by I. Langmuir,16 hasbeen shown by D. L. Hammick, R. G . A. New, N. V. Sidgwick, andL. E. Sutton l7 to be supported by the electrical dipole moment, theinteratomic distance, the heat of formation, the force constant, andthe parachor. N. V. Sidgwick has emphasised that the minutemoment (0-12) of carbon monoxide can be explained only bysupposing that the very unequal sharing of electrons between thecarbon and oxygen is offset by the transference of an electron froml8 W.Hieber 8nd J. S. Anderson, 2. anorg. Chm., 1932,208,238; A., 1932,1219.l4 Idem, ibid., 1933, 211, 132; A., 1933, 476.l6 Proc. Roy. SOC., 1934, [A], 144, 621; A., 833.l6 J . Amr. Chm. SOC., 1919, 41, 1543; A , , 1919, ii, 506.J., 1930, 1876; A., 1930, 1239; 880 also N. V. Sidgwick, Chem. Reviews,See N. V. Sidgwick, " The Covalent Link," 1933, p. 187.1931, 9, 77WAEDLAW : METALLIC CARBONYL AND NITROSYL COMPOUNDS. 103the oxygen to the carbon. The observation of L. E. Sutton andJ. B. Bentley,19 that the electrical dipole moment of nickel carbonylis zero, strongly supports the idea of a triple bond between thecarbon and oxygen, whilst the Raman spectrum of nickel carbonylconfirms the presence in it of a triple link of carbon to oxygen.Nevertheless, objections to this formulation have been raised recentlyby R.Samuel and his collaborators.21 They conclude that theevidence from molecular spectra and considerations of wave-mechanics favour the classical formula (3x0 ; their arguments,however, are based on an interpretation of molecular spectra whichdisagrees with those of W. Heitler and F. London, of L. Pauling,and of J. E. Lennard-Jones. Much more important arguments arebrought forward by L. Pauling,22 who concludes that carbonmonoxide is in resonance between the two forms E O and CEO,with the former predominating.The resonance would explain whythe length and heat of rupture of the link are those required by thetriple link; it would also justify the use of the triple link as thenormal structure. There is, therefore, a very strong case for theview that the triple-bonded structure predominates in carbonmonoxide and that the monometallic carbonyls are correctlywritten as M+-CS6 or M-C&. Sidgwick and Bailey havepointed out a curious regularity in the composition of the carbonyls,whether they contain one or more metallic atoms in the molecule.If we calculate the E.A.N. of the metallic atoms by adding 2 to theatomic number of the metal for each carbonyl group, then thedifference between the result and the atomic number of the nextinert gas is always one less than the number of metallic atoms inthe molecule. For a molecule M,(CO),, the equation G - :(xm + 29)= x - 1 is always true, where m is the atomic number of M and Gthat of the next inert gas.When x = 1 (monometallic), this, aswe have seen, holds in every case. It also holds with all the poly-metallic carbonyls known : Fe,(CO),, Fe,(CO),,, Co,(CO),, andCo,(CO),,. In these, the molecule must be held together by furtherco-ordination, obviously through the oxygen as donor, M-C=O-M,every such link involving the sharing of two more electrons. Ifwe may assume that, as in the simpIe carbonyls, this leads to eachmetallic atom in the polymetallic carbonyls having the E.A.N. ofthe inert gas, it follows from the equation that the number of suchID Nature, 1932, 130, 314; A., 1932, 1077; L.E. Sutton, R. G. A. New,and J. B. Bentley, J., 1933, 652; A., 1933, 765.2o J. S. Anderson, Nature, 1932, 180, 1002; A., 1933, 113.21 H. Leasheim and R. Samuel, Proc. Physicat Soc., 1934,46,523; A., 945;R. I?. Hunter andR. Samuel, J., 1934,1180; A., 1058; Nature, 1934,154,971.22 J . AM. Cbm. Soc., 1932,54,988; A., 1932, 561.+-104 INORaANIC CHEMISTRY.new links through the oxygen must be 1 when 2 = 2, 3 whenx = 3, and 6 when x = 4. This implies that the molecules inquestion are respectively linear, triangular, and tetrahedral, asshown in Figs. 1, 2, and 3. The crystal structures of Fe,(CO),FIU. 1 .-Fe,( CO ),. FIU. 2.-Fe,(CO),2.0c\and Fe,(CO)12 have been examined by R. and are compatiblewith the configurations proposed.The fact that these two substancesare diamagnetic, like Fe(CO), and Ni(CO),, is held to support theseassumptions.In their preparation and properties, the nitrosyl compounds23 2. Krbt., 1927,65, 85; 1931,77, 36; A., 1928, 108; 1931, 671WARDLAW : METALLIC CARBONYL AND NITROSYL COMPOUNDS. 105show a close analogy to the carbonyls. They are commonly formedby the same metals and may be prepared by the direct action ofnitric oxide, like the carbonyls by that of carbon monoxide. It hasbeen suggested that the nitrosyls are derivatives of hyponitrousacid OH*N:N*OH, but there is substantial evidence against such anidea. Nitrosyl compounds are formed from nitric oxide and notfrom hyponitrous acid (except under conditions where the latterforms nitric oxide).Again, hyponitrites in the presence of acidsyield nitrous oxide, whereas nitrosyls readily liberate nitric oxidewith acids, just as the carbonyls liberate carbon monoxide. More-over, those compounds containing one NO group to one metallicatom, such as the nitroprussides, would require a formula doublethe accepted one. There is no evidence in favour of this and muchagainst it. It can scarcely be doubted that each NO group isseparately attached to the metal. The great similarity betweenthe nitrosyls and the carbonyls suggests that their structures arevery similar and that there is a triple bond between the nitrogenand oxygen, giving M-NEO, corresponding to M-CEO.The structure of nitric oxide must, however, differ from that ofcarbon monoxide, for nitrogen has one more electron than carbon.Now it is known that the [NO]' ion can exist in polar compoundssuch as [N0]C104,24 [NO]S0,H,24 and [N0]BF4,25 and N.V.Sidgwick and R. W. Bailey assume that the NO group, like thecarbon monoxide molecule, is attached to the metal by a link oftwo shared electrons, but that, in addition, it transfers a furtherelectron and thereby counts as three towards the E.A.N. of themetal. The suggestion that NO contributes three electrons tothe E.A.N. of the metallic atom has been made already by otherobservers but the detailed mechanism of the linkage has not prev-iously been discussed. The structures proposed are [:N; ;;03+,f - - +- + N-0, M-N-0. Support for this theory is forthcoming in thesimple cases of the carbonyl and nitrosyl compounds of copper.The former 26 are all of the type Cu(CO)Br, where the copper iscuprous, but their nitrosyl 27 analogues are derived fromcupric copper,e.g., Cu(NO)Cl, and Cu(NO)SO,.The extra electron contributed bythe NO group to the copper satisfactorily explains this distinction.Although there is no ferric analogue of the complex compound24 A. Hantzsch and K. Berger, 2. anorg. Clbem., 1930, 190, 321 ; A., 1930,z 5 E. Wilke-Dorfurt and G. Balz, ibicZ., 1927, 159, 197; A., 1927, 120.26 0. H. Wagner, i b d . , 1931, 196, 364; -4., 1931, 581.27 W. Menchot, Annalen, 1910, 375, 308; A., 1910, ii, 956; Ber., 1914, 47,1601 ; A., 1914, ii, 567; W. Manchot and E. Linckh, ibid., 1926,59, 407; A.,1926, 462.1007.D 106 INORQANIC CHEMISTRY.Ms[Fe(CN)5C0], it is notable that ferric derivatives of this type,when they do occur, have the corresponding more stable ferrousanalogues.It is surprising, therefore, that if iron be consideredas ferric in the nitroprussides M,[Fe(CN),NO] no ferrous equivalentis available. However, the theory of the NO linkage advancedby Sidgwick and Bailey removes this anomaly, for on their inter-pretation the iron is ferrous in the nitroprussides. Their explana-tion of the colour reactions of the nitroprussides is particularlyinteresting. It is well known that reaction does not occur withhydrogen sulphide, but addition of alkali or alkaline sulphide to thesolution produces the deep purple colour of M,[Fe(CN),(NOS)] .28Again, hydroxyl ions convert nitroprussides into nitro-compounds,M,[Fe( CN),(N0,)].29 It is considered that the strongly positive+-+ N=O group attracts the negative OH’ or S” (or HS’) ions with theproduction of a nitro- or thionitro-group :0 .SN O N O+-+ Fe-N=O -+ Fe-Nf or Fe-N”The method of formulation adopted by Sidgwick and Bailey fornitrosy1 compounds leads to the maintenance of the inert-gas rulein the majority of cases, even in such complicated molecules as thoseof R~ussin’s ‘f red and black salts,” KFe,(NO),S, and &Fe,(NO),S,.Closely allied to the compounds just discussed are nickel deriva-tives of the type NiSR,NO and the related iron and cobalt compoundsMSR,2NO. Special importance is attached to these substances,for W.Manchot and his collaborators, who systematically studiedthem, consider that the metal atoms exhibit univalency. Beforeaccepting this conclusion, however, it is profitable to examine it indetail. It is obviously arrived a t by considering merely the so-calledprincipal valency of the atom in the sense of Werner’s theory, andneglecting the influence of the NO group. This naturally raises theimportant question as to what is meant by the absolute valencyof an atom in compounds of this type. A definition which willbe universally applicable is not easy to formulate, but on thewhole, the best seems to be that of H. G. Grimm and A. Sommerfeld,mwho consider that the absolute valency of an atom is numericallyequal to the number of electrons of the atom “engaged” inattaching the other atoms.Now, according to Sidgwick and28 J. F. Virgili, 2. anal. Chem., 1906, 45, 409; A., 1906, i, 637.an L. Cambi and L. Szego, Atti R. Accad. Lincei, 1927, 5, 737; A., 1927,30 H. (3. Grimm end A. Sommerfeld, 2. P h y d , 1926,38,36; A., 1926,660.917; (;rclzzettcc, 1928, 58, 71; A., 1928, 345.See also N. V. Sidgwick, ‘‘ The Electronic Theory of Valency,” p. 182WARDLAW: METALLIC CARBONYL AND NITROSYL COBI-POUNDS. 107Bailey’s theory, NiSR,NO should have the structure bd-Si-SR,so that the nickel atom has as many unshared electrons as theisolated nickel atom and hence the valency of the nickel is zero.This is one of the absurdities to which the system of Grimm andSommerfeld occasionally leads, but it does emphasise the difficultyof assigning to the metal atom in these compounds a numericalvalue of absolute valency.There is, of course, no doubt about theexistence of compounds of univalent nickel, as the isolation ofK,Ni(CN), has shown, but the series under consideration are onlycorrectly designated derivatives of univalent iron, cobalt , and nickelin the restricted sense of Werner’s principal valency. In theappended table, the nitrosyl compounds under discussion aresummarised. 31Type MSR,2NO. Type MSR,NO.FeSK, 2N0 FeS,03K,2N0 NiSE t,NOFe4S,K,7NO [F~(S,O~),IK,S~NO NiSPh,NOFeSEt,2NO CoSE t, 2N0 NiSPh,NO,pyFeSPh,2NO CoSPh,2NO “i(SaO,)aIKa,NO[Co(S,O,),IK,,2NOThe mechanism of the reduction to the univalent stage in thecase of the simple mercaptides is very interesting. The nickelmercaptide Ni(SEt),, for example, forms the unstable intermediateproduct Ni(SEt),,2NO, which loses nitrosyl mercaptide, NOmSEt,in accordance with the equations(1) Ni(SEt), + 2N0 = Ni(SEt),,BNO(2) Ni(SEt),,2NO = NiSEt,NO + NOSEtDepending on experimental conditions, the NOSEt undergoes moreor less rapid decomposition into disulphide and nitric oxide :(3) 2NOSEt = 2N0 + EtSmSEt.By similar reactions, ferrous and cobaltous mercaptides yield thecomplex compounds FeSEt ,2NO and CoSEt ,2N0.32 Thesederivatives are covalent, for they dissolve in organic solvents andhave low melting points (polar compounds would have appreciablyhigher melting points).Their intense colours are attributed tothe deformation of the nitric oxide molecule on the basis of Fajans’stheory.The complex thiosulphates are obtained when metallic salts,e.g., nickel chloride or cobaltous acetate, react with nitric oxide in31 See H.Schmid, Angew. Cbm., 1933, 46, 691; A., 14, for detailedreferences.34 W. Manchot and 5. Davidson, Ber., 1929, 62, 684; W. Manchot and H.Gall, Bw., 1927, 60, 2318; 1028, 61, 2393; A., 1928, 35; W. Mrtnchot and F.Kaem, &id., 1927, 60, 2175; A., 1927, 1157108 INORUANIC CHEMISTRY.presence of excess of sodium thiosulphate. The nickel salt,K,[Ni(S20,)2NO],2H,0, is fairly stable, but potassium cyanide 33converts it into the less stable complex cyanide, K,[Ni(CN),NO],which shows the characteristic reactions associated with univalencyof the nickel, vix., pronounced reducing properties and liberationof hydrogen from water.This complex cyanide may also be pre-pared by (a) the reaction between nitric oxide and K,[Ni(CN),] 33or (b) the replacement of carbon monoxide in the complex compoundK,[Ni(CN),CO] 34 by nitric 0xide.~5 It is possible to convert theionised compound K,[Ni(CN),NO] into the covalent Ni(CO),.This is done by addition of acid, which gives the very readily oxidisednickel monocyanide NiCN, which in turn absorbs carbon monoxideto form the unstable intermediate product (NiCN,C0),,34 whichthen decomposes into Ni(CN), and Ni(CO),. W. Manchot andH. Gall36 have suggested an ingenious process for obtaining nickelcarbonyl, based on the above considerations. The process consistsin having a carrier, barium sulphate, associated with a nickel saltwhich is first transformed into a hydrosulphide by hydrogen sulphide.By the action of carbon monoxide on this nickel hydrosulphide, anunstable intermediate compound of univalent nickel is formed whichproduces Ni(CO), in good yield :2Ni(SH), + 2xCO = SNiSH(CO), + H2S22NiSH(CO), = Ni(SH), + Ni(CO), + (2% - 4)CO3.MOLECULAR STRUCTURES.The publication of A. Stock’s Cornell lectures on the hydridesof boron and silicon again focuses attention on a remarkable seriesof investigations which has clarified the chemistry of this verydifficult subject. Included in the volume is a summary of thecontents of 69 papers by the author and his co-workers and 15 byother investigators.An important chapter deals with the structuresof the boron hydrides. These compounds were formerly preparedby the reaction of hydrochloric acid with the so-called “ magnesiumboride ” made from magnesium and boron trioxide. In 1930 B. D.Steele and J. E. Mills 2 found, in their experiments with aluminiumand cerium borides, that the yield of hydrides was better if phos-phoric wits used instead of hydrochloric acid; and A. Stock hasw. w.33 W. Manchot, Ber., 1926, 59, 2445; A., 1927, 33.34 W. Manchot and H. Gall, {bid., p. 1060; A., 1926, 698.35 Schuler, Dim., T. M. Munchen, 1928.3G Bev., 1929, 02, 678; A., 1929, 526; D.R.-P., 577,144.The George Fisher Baker Non-resident Lecturership in Chemistry atJ., 1930, 74; A., 1930, 437.Cornell University, Cornell University Press, 1933.o p .C i t . , p. 43WARDLAW : MOLECULAR STRUUTURES. 109since found that from '' magnesium boride," too, a distinctly betteryield (11 yo instead of 4-5%) is obtained with 8N-phosphoric acid.Silicon hydrides are generally present in the crude gas, but ifberyllium b ~ r i d e , ~ prepared from boron trioxide and silicon-freeberyllium, is used instead of " magnesium boride," this contamin-ation can be avoided. The boron hydrides, belong to two series :B5Hl1, and perhaps B6H12. This is no mere formal classification.The boranes, B,H,+4, are more stable and have relatively highmelting points ; the lower members form stable salts with ammonia.The hydroboranes, B,H12+6, on the other hand, dissociate much morerapidly and melt at considerably lower temperatures than theboranes; their ammonia compounds dissociate even at room tem-perature.The hydrides separated from the crude condensateinclude B,Hl0 (b. p. 1 8 O ) , B6H, and B6H10 (liquids), and BloHl,(m. p. ca. 100"). Other hydrides, B,H,, B,Hg (liquid), and perhapsB6H1,, are obtained by heating B,HIo. No hydride whose moleculecontains one or three atoms of boron is at present known. Themost important hydride B2H6 cannot be prepared directly from aboride and acid, for it is decomposed by water : B2H6 + 6H20 =2H,BO, + 6H2. Recently, however, A. B. Burg and H. I. Schlesin-ger 6 have discovered a new method of preparing it. They subjecta current of hydrogen mixed with gaseous boron trichloride, atreduced pressure, to a high-tension electric discharge.In additionto hydrogen chloride, boron, solid hydrides of boron, and someB,H6, much B,H,C1 is produced, which, on standing, dissociatesrapidly into B2H6 and BCl,. are ofopinion that better results are obtained by using the tribromideinstead of the trichloride. By the reaction of B2H6 and methylalcohol,7 the interesting substance dimethoxyborine (m. p. - 130-6')is produced, 4MeOH + B,H6 = 2BH(OMe), + 4H,, accompaniedby an unstable by-product, possibly a polymeride of BH,OMe.Water rapidly decomposes dimethoxyborine : BH( OMe), +3H20 = B(OH), + 2MeOH + H,.The structure of B2H, is a perpetual puzzle, and in spite of thegreat ingenuity displayed by numerous writers, it appears that nocompletely satisfactory solution has yet been reached.The mostimportant reagent for diagnosing the structure of the boron hydrides(l) B?ZH7&+4 ' B2H6, B,Hg, B6H10, BloH14; (2) B7&H??+6 ' B4H10,A. Stock and W. Siitterlino p . cit., p. 48.5 J . Amer. Chern. Soc., 1931,!53,4321; A., 1932,350; A. Stock, H. Martini,6 Ibid., p. 407 ; A., 497.7 A. B. Burg and H. I. Schlesinger, J. Amer. Chm. Soc., 1933, 55, 4009,and W. Sutterlin, Ber., 1934, 67, [B], 396 ; A., 497.4020; A,, 1933, 1257I10 INORGANIC CHEMISTRY.is ammonia. This forms a, series of salts such as B2H,,2NH3,8B ~ H ~ O , ~ N H ~ , ’ B5H9,4NH3,10 and BloH,4,6NH,,10 and their exist-ence is interpreted as indicating the presence of a proportion ofatoms of acidic hydrogen in the hydrides.Substitution productsmay be formed by electrolysis of the boron hydrides l1 in liquidammonia. When thus electrolysed, B2H6 has a conductivity whichis considered to be due to the diammine B2H,,2NH3 acting as the,salt [B,H,](NH,),. By a secondary reaction, the ions [B2H4]” and[NH,]’ yield hydrogen and B,H5,NH2, which st,ill can form a salt(NH,),[B,H,*NH,]. Electrolysis of this substance gives hydrogenand B2H4(NH2),. The unsaturated character of the boron hydridesis indicated by the observation that two atoms of sodium may beadded to B,H, 8 and B ~ H I , . ~ The above results are explained byassigning to B2H, and its derivatives the formulae : l2[$3---Byg] YH 2Na+ r NH, Hp=~<r2] 2NH,+I 1-Higher homologues of this series may be similarly formulated.Insupport of these formuh it is mentioned 13 that the ultra-violetabsmption spectrum of B2H6 resembles that of ethylene rather thanthat of ethane, and that the absorption of B,Hlo is similar to thatof the conjugated hydrocarbon butadiene, CK,:CH*CH:CH,. Whencertain ammonia addition products such as B2H6,2NH3 are heatedto about 200” for several hours, the exceptionally stable compoundB3N3H6 l4 is obtained. Its similarity to benzene in certain physicalproperties has suggested that its structure is probably representedby the inset formula : the double and single bonds can be inter-changed exactly as in Kekuk’s formula for +&~H-GH benzene.In 1856 J. Nessler proposed the use ofan alkaline solution of mercuric iodide andpotassium iodide as a reagent for the direct determination ofammonia, and many studies have since been made of the brown com-pound obtained in this reaction.Some recent observations of M. L.Nichols and C. 0. Willits l5 indicate that it has the composition* A. StockandE. Pohland, Ber., 1926,459, [B], 2210; A., 1926, 1317.A. Stock, E. Wiberg,and H. Martini, Ber., 1930, 63, 2927; A., 1931, 50.lo A. Stock and E. Pohland, Ber., 1929, 02, 90; A., 1929, 279.l1 Op. cit., Chap. 21.l2 E. Wiberg, 2. anorg. Chern., 1928, 173, 199; A., 1928, 036.l3 Op. cit., Chap. 26.l5 J. Amer. Chem. Soc., 1934,50, 769; A., 614.‘EH‘BH=b€’l4 Op. cit., Chap. 14WARDLAW : MOLECULAR S!t%UCTDRES. 111represented by the empirical formula, NH,*Hg,I,.It is very in-soluble and tends to separate in very minute particles which arenegatively charged and give colloidal solutions. Owing to theagglomeration of the particles, the yellow colour changes to redwhen ammonia solutions of higher concentration are utilised. Thismay be prevented, and the colour made permanent over awide range of ammonia concentrations, by adding a protectivecolloid, e.g., the addition of 1 C.C. of an 0.5% alkaline ash-freegelatin solution containing 1% of perhydrol to 50 C.C. of Nesslersolution.In connexion with the structure of hydrazoic acid and the azides,some observations by E. C. Franklin 16 are of interest. From hisexperimental results, he concludes that most of the reactions ofhydrazoic acid support the idea that it is an ammononitric acid,H - N = m .This linear structure, originally proposed byThiele, is nowadays more correctly written as H-N=lu-N.The action of hydrazoic acid on the metals bears a striking resem-blance to that of nitric acid. Cont'rary to the statements of previousinvestigators, which are reproduced in most text-books, Franklinfinds that no hydrogen is evolved when the acid is treated with zinc,iron, manganese, nickel, or copper. The products are metallicazides, nitpogen, ammonia, and small amounts of hydrazine. Withmagnesium, however, a small amount of hydrogen may be detected,recalling the fact that this metal yields some hydrogen with verydilute nitric acid. Ferrous azide is converted into ferric azide whenheated with excess of hydrazoic acid.Potassium azide may beproduced by heating a solution of potassium nitrate and potassamidein liquid ammonia : KONO, + SKNH, = KN=N=-N + 3KOH +NH,.Whilst the chemical evidence indicates a linear structure for theacid and its salts, the results from crystal structures l7 show clearlythat this applies also to the ion [NfiNfN]. Again, N. V.Sidgwick,lB in discussing the structure of organic azides, concludesthat an organic azide is a mixture of two open-chain forms (a)and (b) in resonance : (a) R-N=NtN, ( b ) R-NtN-N. Afascinating example of the linearity of the arrarigement of the nitro-gen atoms in the azide group was recently disclosed by an X-rayexamination of cyanuric triazide, C,N,(N,),, by (Miss) I. E. Knaggs.(Sir) W.H. Bragg19 has pointed out that the arrangement bearsl6 J . Amer. Chern. SOC., 1934,56, 668; A., 477.17 S. B. Hendricks and L. Prtuling, aid., 1925, 47, 2904; A., 1926,18 Trans. FaracEay SOC., 1934,30, 801.l9 Nature, 1934,134, 138; A., 948.113112 INORGANIC CHENISTRY.a resemblance to the arms of the Isle of Man, a row of three nitrogenatoms lying in the position of each leg from knee to ankle.N 7A number of substances are described in the literature as cadmouscompounds, e.g., a sub-halide Cd,Cl, which is supposed to be formedby fusing anhydrous cadmic chloride with metallic cadmium innitrogen. (Miss) W. R. A. Hollens and J. F. Spencer 2o find thatthis is really a mixture, for the observed mass susceptibility equalsthat calculated for the mixture Cd + 7CdC1,.They have alsoproved that the so-called cadmous hydroxide and oxide preparedfrom Cd4C1, are mixtures of cadmium and the corresponding cadmiccompound. The relationship between the colour and crystallhestructure of precipitated cadmium sulphide has been examinedby W. 0. Milligan.21 He infers from his X-ray measurements thatboth the cubic p-CdS and the hexagonal a-CdS may each be yellowor red depending on the conditions of precipitation, and attributesthese colour differences to variations in particle size and nature ofsurface. From the cadmium halides, the a-CdS is the main product,whilst from the sulphate and the nitrate (in hot, acid solution) the$-CdS is obtained.Some important observations on the so-called calcium sulphatehemihydrate, which is generally recognised as the active principleof plaster of Paris, have been recorded by W.A. CasparLZ2 Fromsolutions of calcium sulphate in hydrochloric, sulphuric, or nitricacid under proper conditions as to dilution of the solvent and tem-perature, crystals of “ hemihydrate ” 0.5-1 mm. thick and 3 4 mm.long can be obtained; these belong to the trigonal system, with adensity not far below that of anhydrite. In its air-dry condition,the crystal usually contains not more than 4.0--4*5% of water,corresponding rather to 3CaSO,,H,O than to 2CaS0,,H20. Themoisture content of the “hemihydrate” has been shown byprevious investigators, working upon less well-defined materials,to be held in the same way as that of zeolites.Experiments withthe trigonal crystals confirm this, for they may be made to giveao J., 1934, 1062; A., 978.22 Nature, 1934,133, 648 ; A,, 720.21 J. Physical Chem., 1934, 38, 797WARDLAW : MOLECULAR STRUCTURES. 113up water to within 0.1% or less of complete dehydration withoutloss of form or transparency. Exposure to moist air causes theoriginal degree of hydration to be gradually regained. “Deadburning ” converts these trigonal crystals into pseudomorphsconsisting of ordinary anhydrite. Caspari concludes that anhydriteis apparently dimorphous, there being an orthorhombic, com-pasatively inert modification, and a trigonal form, stable only upto ca. 200”, which can take up water zeolitically. It is the behaviourof the latter form in contact with water that causes plaster to set.The suggestion is made that there may be no essential differencebetween the “ soluble anhydrite ” and the ‘‘ hemihydrate ”mentioned in the literature of calcium sulphate.The diamond has been studied for a longer period than anyother natural stone, and its unique character has always beenassumed.It has been left to (Sir) R. Robertson, J. J. Fox, andA. E. Martin 23 to make the fascinating discovery that there are twotypes of diamond which show striking differences in a number ofphysical properties, while in other properties no differences whatevercan be observed. They find that diamonds showing a laminarstructure (I) differ in certain properties from ordinary diamonds(11); the latter have an infra-red absorption band at 8 p and areopaque t o ultra-violet light of less than 3000 8., whilst (I) have noband at 8 p and are transparent up to 2250 8.With (11) the con-ductivity induced by light is very small, high voltages having to beapplied before a current can be detected, whilst (I) give an appreciablecurrent without an applied voltage. Also, (I) are activated bylight of 2300 8., and afterwards give a current in the dark and alarge current when re-illuminated with light of more than 5000 8.These activated diamonds are deactivated by light of 2400-5000 8.X-Ray examination indicates that (I) have a mosaic structure;they are also more optically isotropic than (11), but the specificgravity, refractive index, dielectric constant, and Raman effectare the same for both types. It is considered that the differencebetween (I) and (11) is not due to impurities, but to different con-ditions resulting during their formation from the plastic state.A useful addition to the chemistry of zirconium has been madeby M.P i ~ o n , ~ ~ who has prepared three definite sulphides, ZrS,,Zr3S,, and Zr2S,, of which the last two are new. The method ofpreparation was to act on zirconium oxide at a high temperaturewith hydrogen sulphide. By heating first at 1100-1200” andthen raising the temperature to 1700”, a fused crystalline mass of23 Phil. Trans., 1934, [A], 232, 463; A., 583.24 Cmpt. rend., 1933, 196, 2003; 197, 151; A., 1933, 918; Bull. SOC. chim.,1933, [iv], 58, 1269; A,, 1934, 266114 INORGANIC CHEMISTRY.Zr3SG was obtained.On heating this at 900-1300" in hydrogensulphide, the black ZrS, was produced. Brown Zr,S3 was formedwhen Zr,S, was heated at 1400" for 2 hours in a cathode-ray vacuumor at 1700" for one hour in hydrogen. All the products were crystal-line. Evidence of the existence of Zr,S, was also obtained. Anexamination of the chemical properties of these substances indicatedthat the action of numerous reagents was less pronounced with thecompounds containing less sulphur.The main product of the action of gaseous fluorine on sulphur isthe hexafluoride, SF,, which is a highly stable gas. In addition,two other fluorides S2F2 and SF, are described in the literature,although N. V. Sidgwick 25 has directed attention to the possibilitythat SF, may not exist.In a recent communication by K. G.Denbigh and R. Whytlaw-Gray,26 the preparation and propertiesof a new fluoride, disulphur decafluoride, S,F,,, are described. Thisvery interesting substance was obtained by the fractionation ofa large quantity of the hexafluoride. Only small quantities are pro-duced in the reaction of fluorine on sulphur, but the yield is improvedby using plastic instead of rhombic sulphur. This new fluoride isstable, but less so than the hexafluoride. Its b. p. is 29", m. p. -92",and liquid density 2-08 g./c.c. The parachor is in fair agreementwith a sexacovalent structure which, moreover, appears mostprobable on chemical grounds. The two sulphur atoms are linkedtogether by a single bond, and each sulphur carries five fluorineatoms also linked by single bonds.Valuable information continues to accumulate about the chloridesof sulphur.Por a number of years, T. M. Lowry and his collaboratorshave been investigating the mechanism of the formation of thesecompounds. In 1927 27 they discovered that sulphur and chlorine,after being heated in sealed tubes at loo", gave a product with afreezing-point curve which showed, in addition to the familiarmaxima due to the mono- and tetra-chlorides, two well-definedbreaks which they attributed t o crystallisation of the dichloride anda new chloride S,Cl,. Later work demonstrated that the tetra-chloride could exist only in the solid state. The fact that thedielectric constant of the solid tetrachloride was much higher thanwould be expected for anything but a salt led Lowry and G.Jessop 28to suggest that it is a polar compound; they therefore assignedto the tetrachloride the structure [$C13fil, and to the new chlorideS,C1, the configuration c l e s ~ ~ ~ l or [S',Cl3]fi. The so-calledc1.s c125 Ann. Reports, 1933, 30, 126.2 7 T. M. Lowry, L. P. McHatton, and G. 0. Jones, J., 1927,746; A., 1927,505.28 J . , 1929, 1421; A., 1929, 978; J., 1930, 782; A., 1930, 666.a6 J., 1934, 1347WARDLAW : MOLECUL-4R STRUCTURES. 115sulphur monochloride, S,CI,, still presented an interesting structura1problem, and recently A. H. S ~ o n g , ~ ~ in Lowry's laboratory, re-viewed the relevant physical data available (e.g., Raman spectrum,parachor, and dielectric properties) and concluded that ordinarysulphur monochloride is probably a mixture of the two forms (1)"--S<Cl and (2) Cl*S*S*CI.He has also investigated the reactionbetween sulphur monochloride and chlorine, which is generallyrepresented by the simple equation S,C1, + C1, = 2SC1,. It is,however, recognised that the reaction is definitely more complicatedthan this, and A. H. W. Aten 30 had suggested that it is an auto-catalytic reaction, both the di- and the tetra-chloride being activein catalysing the process. A. H. Spong 31 now finds that no effectascribable to sulphur tetrachloride can be observed, but that thereaction velocity is markedly influenced by the concentration ofS,C14. He considers that the primary mechanism is probablyionic, the chlorine ion attacking the negatively charged sulphuratom in the modification of the monochloride with formula (1).The mechanism he proposes is :+ c1(a) S,C12 + Cl = SCI, + SCl(b) $&C13 f- sc1 = SCI,-s3CIzV.Zappi and V. Cortelezzi 32 examine the experimental data whichare held to favour polar structures for certain halogen derivativesof the nonmetals. The evidence for this possibility in the case ofphosphorus pentachloride was very slight ; according to A. Voigtand W. Biltz,= the compound is entirely non-conducting, andJ. H. Simons and G. Jessop support this c0nclusion.~4 Moreover,these investigators point out that a polar formula is definitelyruled out by their observation that, in carbon tetrachloride, phos-phorus pentachloride has zero or a very small dipole moment.The support for a polar structure is the experimental data of G.W. F.Holroyd, H. Chadwick, and J. E. H. MitchellY35 who found that thepentachloride had a small conductivity in nitrobenzene but none inbenzene and ethylene dibromide. Now Zappi and Cortelezziconclude from their experiments that such measurements in nitro-benzene are subject to large errors and are unreliable. They find,however, that solutions of phenyl dichloroiodide in carefully purified28 J., 1934, 485; A,, 605.31 J., 1934, 1283.33 2. anorg. Chem., 1924,133, 297; A., 1924, ii, 552.34 J . Amer. Chem. SOC., 1931, 53, 1263; A., 1931, 669.35 J., 1925, 127, 2492; A., 1926, 15.30 2. phy8ikal.Chem., 1905, 54, 55.33 Bull. SOC. chim., 1934, [v], 1, 509116 INORGANIC CHEMISTRY.nitrobenzene and in phosphorus oxychloride show a very feebleelectrical conductivity, whilst the cryoscopic molecular weight islow. They contend that this does not indicate that the structure is[PhICI'JCl but that the experimental results may be due to dissoci-ation in accordance with the equation : PhICl, 2 PhI + Cl,.They also examine critically similar experimental data given byother compounds such as iodine trichloride, and conclude that thefeeble conductivities which have been recorded may be morerationally explained as due to the dissociation of complexes formedwith the solvent. Cryoscopic dissociation they also regard as mole-cular and not ionic.The conclusion that phosphorus pentachlorideand iodine trichloride are covalent compounds will be generallyaccepted.The iodine in periodic acid tends to pass into the 6-covalent state,so that the ordinary periodic acid is H,[IO,]. The 4-covalent formHCIO,] has been only once described, but J. R. Partington and R. K.Bahl*6 now show that HIO, is a definite compound, although noevidence could be found of the existence of the anhydride I,O, or ofmesoperiodic acid H,IO,. Periodic acid, H510,, at 100" in a vacuumloses 2H,O and HIO, is formed. On heating at 80" in a vacuumtwo molecules of H510, lose 3H,O, H4120g being formed.In general, cupric copper does not readily form 6-co-ordinatedcompounds, and its covalency is normally 4. It was surprising,therefore, when in 1927 W.Wah13' stated that he had prepareda laevorotatory iodide [C~(en)~(K,0),]1, and thus established that6-covalent copper was of octahedral type. Now, C. H. Johnsonand S. A. Bryant 38 have reinvestigated this matter. All theirattempts at a resolution were unsuccessful, and moreover, theiranalyses show that there are no grounds for presuming that theion [Cu(en),(H,O),]" is present in the crystalline salt. Theyincline to the view that the constitution of the ion in the crystalis [Cu(en),]", where the covalency of the copper is 4 and not 6, andso optical isomerism cannot arise. Some earlier work of G. T.Morgan and his co-workers lends support to this structure.The valuable co-ordinating properties of the tridentate group2 : 2' : 2"-tripyridyl (trpy) have been applied with success to theproblem of the structure of 4-covalent compounds of platinum.G. T.Morgan and F. H. Burstal139 have succeeded in isolatinga red crystalline salt, [Pt(trpy)Cl]C1,2 or 3H,O, andl thereby pro-vided an elegant chemical proof that in this co-ordination compound313 J., 1934, 1088; A., 979.3 7 Acta Sci. Fennlzicae Comrn. Phys.-Math., 1927, 4, 1; A., 1928, 395; Ann.Reports, 1933, 30, 100.J . , 1934, 1783. Ibid., p. 1498WARDLAW : MOLECULAR STRUCTURES. 117the four valencies of the platinum atom must be planar, for a tetra-hedral structure is inadmissible. If a model of this molecule (I) isbuilt up on the assumption that the pyridine rings have the Kekul6structure, it will be found that chelation can take place withoutI C1undue strain only if in two of the pyridine rings the double bondsare fixed, i.e., not oscillating between the two possible Kekult5forms.F.G. Mann 40 has shown that pp’-diaminodiethylamine,(NH,*C,H,),NH, can act as a tridentate group with platinous salts,but as this triamine may occupy the three points of a triangularface, it is uncertain whether the salt [BrPt(NH,*C,H,),NH]Br isplanar or tetrahedral. Further interesting stereochemical questionsare raised in a paper by G. T. Morgan and F. H. Burstall 41 dealingwith 2 : 2’-dipyridylplatinum salts, and in a communication byJ. S. Anderson 42 on Zeise’s salt K[PtC1,,C,H4],H,0.In 1930, F. G. Angell, H. I>. K. Drew, and W. Wardlaw 43 broughtforward new experimental data about the two known forms of thethio-ether addition compound (Et,S),PtCI,, which indicated thatfurther investigation of this group of substances was necessary asthe chemical evidence available did not afford any confirmationof the planar structure.The results of recent chemical and X-rayexperiments by E. G. Cox, H. Saenger, and W. Wardlaw 44 with thedimethyl sulphide derivatives of platinous and palladous chlorides,[Pt(Me,S),CI,] and [Pd(Me,S),Cl,], prove that the two isomeridesof the former are planar cis-tram-compounds. The a-form is thetrans-compound, not the cis- as suspected by Werner, and it is nottetrahedral as suggested by others. The X-ray results with thep-isomeride are less definite, but it seems likely that the sulphuratoms are in cis-positions and that the compound is ionised in thesolid state.I n the case of the palladous compound, only one formwas obt’ained ; this is isomorphous with the a-platinous compoundand is therefore the plane trans-compound. The chemical re-actions of the substances differ very considerably, notably witahsilver oxide. The p-platinous compound reacts rapidly with this40 J., 1934, 466; A., 640.42 Ibid., p. 971 ; A., 994.44 J., 1934, 182; A., 397.41 Ibid., p. 965; A., 1113.43 J., 1930, 349; A., 1930, 559118 INORGSNIC CHBMISTRY.reagent, with production of silver chloride and a basic substancewhich forms an alkaline solution in water and yields the originalsubstance with acid. The a-form, on the other hand, reacts onlyslowly, with evolution of dimethyl sulphide and precipitation ofplatinum as hydroxide or oxide.The so-called third form ofPt(Me,S),CI, has been shown by L. Tschugaeff and W. Surbotin 45to be really the plato-salt, [Pt(Me2S!4][Pt.C14], a result confimedby the present investigators. The diethyl sulphide derivatives ofplatinous and palladous chlorides have also been submitted toa detailed chemical examination by H. D. K. Drew and G. H.Wyatt,46 who draw conclusions regarding the structures, sub-stantially in agreement with the results obtained for the dimethylsulphide derivatives.Palladium, like platinum, has been shown by X-ray47 methodsto give planar configurations in certain of its 4-covalent compounds.In no case, however, had the cis- and trans-isomerism demanded bytheory been established.Recently,48 from the reaction of glycineand potassium chloropalladite, two substances were isolated, vix. ,yellow prisms, Pd(NH,~CH,*CQ,)2,3H20, and glistening, light yellow,anhydrous plates. These have been shown by X-ray and chemicalexperiments to be different in structure and to have the cis-trans-planar configurationsA. A. Griinberg and V. M. Schulman 49 have also described two formsof Pd(NH,),CI, which they consider to be cis- and trans-isomerides.4. SOME RARER METALS.Considerable attention has been given in recent years to theso-called “rare elements,yy and results of great interest have beenobtained in what is undoubtedly a very profitable field of chemicalinvestigation.Nowadays, the description “ rare ” is not veryfitting, for most of them can be obtained in it pure form withoutdifficulty. Apparently, the rare earths of the yttrium group,especially those with odd atomic numbers, are still difficult to obtainpure. Workers on rhenium have been particularly active, but muchresearch remains to be done before the chemistry of this element issatisfactorily elucidated.w. w.45 Bw., 1910, 43, 1200; A., 1910, i, 354.4 7 Ann. Reports, 1933, SO, 108.40 J., 1934, 56; A., 284.F. W, Pinkard, E. Sharratt, W. Wardlaw, and E. G. Cox, J., 1934, 1012;A., 994.49 Compt. rend. Acad. Sci. U.R.S.S., 1933, 1, 218; A., 1934, 379WARDLAW : SOME RABER METALS. 119Although the account given in the following pages can in no senseclaim to be complete, it is hoped that it will provide an indicationof the kind of investigation that has been going on in the cases ofgermanium, gallium, indium, and rhenium.Germanium.-Discovered in 1886, germanium was consideredto be one of the rarest of elements until it was shown in 1916that the spelter residues from certain American zinc ores maycontain up to 0.25% of germanium dioxide. Pour years later, therewas found at Tsumeb, S.W. Africa, a sulphide ore, germanite,stated to have a germanium content of 5-6%, which has beenmade available in large quantities by the Otavi Minen undEisenbahn Gesellschaft.2 There is no doubt that the discoveryof these new sources of the element and the improved methods thathave been elaborated for its extraction have given an impetusto investigations of this interesting member of the fourth group.Prom the many contributions which have appeared in recent years,important relationships to carbon and silicon, on the one hand,and tin and lead, on the other, have been established.In an electrochemical investigation, J.I. Hall and A. E. Koenighave obtained coherent grey deposits of germanium, on copper, byelectrolysis of a solution of the dioxide in 3N-potassium hydroxideat 78-90', with a low current density. They find that germaniumwill displace silver from aqueous silver nitrate. An interestingobservation has been made with the dioxide, GO,.* Two crystallinemodifications have been identified, one isomorphous with quartzand the other with cassiterite (SnO,) and plattnerite (PbO,);a remarkable feature of these two forms is the difference in density(4.28 and 6.26).5 The literature relating to the hydrides and theirhalogen derivatives is very voluminous.C. A. Kraus and E. S.Carney have shown that, by treating magnesium germanide withammonium bromide in liquid ammonia, a yield of 60-70% ofmixed germanes can be obtained instead of the possible 22% whenhydrochloric acid is employed. Incidentally, it may be mentionedthat a mixture of silicon hydrides in good yield is obtained by drop-ping Mg,Si into a solution of ammonium bromide in liquid ammonia.'G. H. Buchanan, J. Ind. Eng. Chem., 1916,8, 585; A,, 1916, ii, 486.a See W. I. Patnode and R. W. Work, I d . Eng. Chm., 1931,23, 204; B.,1931, 495, for references to history of germanite and earlier methods ofextraction.Tran8.Amer. Electrochem. SOC., 1934, 65, 79; A., 735.4 V. M. Goldschmidt, 2. physikal. Chem., 1932, 17, 172; A., 1932, 681;A. W. Laubengayer and D. S. Morton, J . Amer. Chem. SOC., 1932,54,2303; A.,1932, 905.6 A. W. Laubengayer and D. S. Morton, Zoc. cit.Ibid., 1934, 56, 765; A., 615.W. C. Johnson and T. R. Hognew, ibid., p. 1262; A., 742120 INORGANIC CHEMISTRY.Particular reference, however, should be made to the isolation ofthe hydrides (GeH)z and (GeH2)r. The monohydride 8 is preparedby the action of cold water on sodium germanide, NaGe, as a darkbrown powder which yields germanium and hydrogen at 165".The dihydride results when calcium germanide, CaGe, is treatedwith acid.It is an amorphous yellow compound, quite stable whendry but explosively reactive with oxygen. Pyrolysis at 120-220"gives a mixture of GeH,, &,Ha, Ge3H8, and hydrogen with aresidue of germanium. The chemical behaviour of (GeH,),indicates an open-chain structure of high molecular weight, analogousto that of the polyoxymethylenes.A systematic study of certain derivatives of bivalent germaniumhas given much useful information. The sequence Ge, Sn, Pbindicates that the dichloride should be unstable, and so it is notsurprising that it was not isolated until 1929, when L. M. Dennisand H. L. Hunter 10 prepared it as a crystalline, colourless massby leading the tetrachloride (b. p. 86") over heated germanium andquickly cooling the vapour.Previously, in most text-books thiscompound was described as a liquid. Germanium sulphide, GeS,was first described by C. A. Winkler, and a study of its preparationby reduction of the disulphide GeS, with hydrogen was made byL. M. Dennis and S. M. Joseph; 11 by this method it is obtainedas a black crystalline solid. A red form is obtained when hydrogensulphide is passed into a hot solution of the dichloride, and the redprecipitate dried in nitrogen at 300". When heated for a few hoursin nitrogen at 450", the red reverts to the black form.12 It is interest-ing to notice that the monoxide, GeO, is a jet-black crystallinecompound which sublimes in nitrogen at 710".12Amongst the nitrogen compounds, two nitrides are known,Ge3N4 and Ge,N,.Germanic nitride l3 can be prepared by theaction of gaseous ammonia on germanium at high temperatures orby thermal decomposition of germanic imide, Ge(NH2),, which isa light white powder obtained by the ammonolysis of GeC1, inliquid ammonia. At 150" the imide loses ammonia and formsgermanam, &,N,H, for which the formula (I) has been proposed.148 L. M. Dennis and N. A. Skow, J . Amer. Chem. SOC., 1930,52,2369; A,,P. Royen and R. Schwarz, 2. anorg. Chern., 1933,211,412; A., 1933, 579;1930, 1007.ibid., 1933, 215, 295; A., 1934, 158.10 J . Amer. Chem. SOC., 1929,51, 1151; A., 1929, 662.l1 J . Physical Chem., 1927, 31, 1716; A., 1928, 33.la L. M. Dennis and R. E. Hub, J . Amer. Chern. SOC., 1930, 52, 3553; A.,lS W.C. Johnson, ibid., p. 516; R. Schwarz and P. W. Schenk, Ber., 1930,14' J. S. Thomas and W. Pugh, J., 1931, 60; A., 1931, 322.1930, 1387.63, [B], 296; A., 1930, 437WARDLAW : SOME RARER METALS. 121Germanous imide l5 may be prepared from the di-iodide and am-monia : GeI, + 3NH, = GeNH + 2NHJ. When heated to250-300" for several hours, it gives GR3N2,16 a finely divided brownpowder : 3GeNH = &3N2 + NH,.Germanium is now included in the list of elements which formheteropolyacids l7, l8 of the type H,[X(R,O,),], where R = Moor W, and X may be one of the following Group IV elements : Si,Ti, Zr, Th, Sn, Pb, Ge, and possibly Hf. The free acid,H8[Ge(Mo,0,),],aq., has a varying water content and crystallisesin yellow transparent octahedra readily efflorescing, and withm.p. ca. 65".18 The organo-metallic compounds of germaniumhave been widely investigated. Amongst the many interestingresults obtained, mention may be made of the fact that R. Schwarzand M. Lewisohn 19 have prepared an optically active phenylethyl-isopropylgermanium bromide, and have also described the aromaticgermanium compound (11).Ph Phph PhFinally, there is evidence of the existence of derivatives of per-germanic acid. The per-compounds of the Group IVu elements,titanium, zirconium, and thorium, with the general formula H,MO,where M = Ti, Zr, or Thy are well known. In Group IVb the ten-dency to per-acid formation is appreciably less, so that with leadsuch substances are unknown, and with tin, the perstannateNa,Sn,O,,SH,O is very unstable.,O Germanium, however, forms well-defined per-compounds, and Schwarz and Giese have announced thepreparation of K,&,07,4H,O, Na,Ge20,,4H20, and Na,Ge05,4H,0.These authors were unable to isolate a crystalline persilicate, butobtained an oil which may have contained some decomposedpersilicate.On the other hand, F. Krauss,21 by evaporatinga solution of sodium silicate treated with hydrogen peroxide,obtained a powder which he considers to be Na,Si03,H,0,2H20,.Evidently he does not regard this product as a true persilicate.Gallium and Indium.-As gallium is present in nearly all1 6 W. C. Johnson, G. H. Morey, and A. E. Kott, J . Amer. Chern. SOC., 1932,16 W. C. Johnson and G. H. Ridgely, ibid., 1934,56, 2395.l7 A. Brukl, Monatsh., 1930, 56, 179; A., 1930, 1538; R.Schwarz and H.54,4278; A., 1933, 38.Giese, Ber., 1930, 63, 2428; A., 1930, 1637.C. G. Growcup, J . Arner. Chem. SOC., 1930,52,5154; A , , 1931, 322.Ber., 1931, 64, 2352; A,, 1931, 1435.2. anorg. Chm., 1932, 204, 318; A., 1932, 350.2o R. Schwarz and H. Giese, Ber., 1930,68, 780; A., 1930, 720122 IXOR43ANICl CHEMISTRY.germanium-containing blendes and also occurs in germanite to theextent of ca. 0*6%, its extraction generally accompanies that ofgermanium. The 'University of Colorado has recently publisheda " Bibliography of Indium," 22 in which communications from thedate of the discovery of the metal in 1863 to 1933 are classified.Most of the work on indium appears to have been published inGermany and the United States, but the United Kingdom is repre-sented by the work of (Sir) H.C. H. Carpenter and S. TamuraBon twinned metallic crystals, some older work of Roberts-Austenand T. Carnelley, and an investigation of indium acetylacetone byH. D. K. Drew and G. T. Morgan.24Within the last few years, important additions to the fundamentalchemistry of gallium have been made. Its tri-bromide and tri-iodide were prepared for the fkst time in 1930,,5 and in the sameyear it was proved that, not only did sulphides of bi- and ter-valentgallium exist, but also the sulphide of the univalent element.26The yellow crystals of Ga,S, were obtained by passing nitrogen andsulphur vapour over the metal a t 1200" ; when reduced by hydrogena t 800°, it gave a glistening yellow sublimate of Gas, which onbeing heated in a high vacuum yielded Ga,S, and the volatile Ga,S.This new sulphide is greyish-black and readily oxidised.- A numberof selenides have been synthesised : Ga,Se, GaSe, Ga2Se3, In,Se,InSe, and In,Se,, and by the thermal analysis of the systems Ga-Teand In-Te, the existence of the following tellurides has beendemonstrated: GaTe, Ga2Tes, InTe, and In,Te,. The oxide ofunivalent gallium, Ga,O, has been obtained 28 but GaO is unknown.A remarkably stable nitride was isolated in 1932 by the interactionof ammonia and gallium at 900°.29 It is unattacked by concentratedhydrochloric, hydrofluoric, or nitric acid or by hot aqua regia.Even hot concentrated sodium hydroxide dissolves it but slowly.C. A.Kraus and F. E. Toonder30 have prepared organometalliccompounds of gallium which show the expected analogy to theaa '' Studiea," 1934, 21, No. 3.ad J., 1924, 1261; A., 1924, i, 941.26 W. C. Johnson and J. B. Parsons, J. Physical Ch., 1930,34, 1210; A . ,1930, 874.26 A. Brukl and G. Ortner, Naturwiss., 1930, 18, 393; A., 1930, 720;Monatsh., 1930, 56, 358; A., 1930, 1537; W. C. Johnson and B. Warren,Naturwiss., 1930, 18, 666; A,, 1930, 1138.Bull. Inat. Min. Met., 1928, No. 282; A., 1928, 603.27 W. Klemm and H. U. von Vogel, 2. anorg. Chem., 1934,219,46; A., 1081.28 A. Brukl and G. Ortner, 2;. anorg. Chem., 1931,203,23; A., 1932,238.2B W. C. Johnson, J. B. Parsons, and M. C. Crew, J . Physical Chem., 1932,Proc.Nat. Acad. Sci., 1933,19,292; A., 1933, 599; J . Amer. Chem. SOC.,36,2588; A., 1932, 1218.1933, 55, 3547; A., 1933, 1150WARDLAW : SOME RARER METALS. 123corresponding zinc derivatives. I n the third group of the PeriodicTable from boron to thallium, either the normal trimethyl or triethylcompounds or both have now been prepared. The series was com-pleted in 1934 by tho isolation of trimethylindi~rn,~~ a colourlesscrystalline solid which gives a molecular weight in benzene in accord-ance with the polymeride [In(CH,),],. I n the following table,based on that given by W. Klemm,32 the types of compound thatexist for the different valencies are summarised.Valenc y . Valency.Gallium. 1. 2. 3. Indium. 1. 2. 3.c1 ............ - + + c1 ............+ + +Br ......... - + + Br ......... + + + ............ I ............ + + + I - - . +0 (+) - + 0 (+I 3. s ............ (+I + + s ............ + + + ............ ............(+) = Prepared from the gaseous state by cooling but not stable; decom-posed on heating; + = prepared by synthesis and stable; - = not yetprepared and probably non-existent.The summary shows that for both elements uni-, bi-, and ter-valent compounds exist. The tendency to exist in the univalentstage is less for gallium than for indium, whilst with thallium it isgreatest. Bivalent compounds do not appear to be very stable.In the tervalent state, the halides are almost all colourless; ex-ceptions are GaI, and I d 3 , which are yellow. Klemm 32 has pointedout an interesting relation between colour and constitution in thecompounds of gallium and indium: those of the bivalent stageshow no appreciable colour deepening compared with the tervdentstage, whereas the unsaturated compounds of the univalentstage are quite dark.He concludes that this anomaly is explainedby the magnetic properties. The bivalent gallium and indiumcompounds are diamagnetic. Now as Ga" and In" ions containa free electron, they should show paramagnetism. Evidently theseions combine with spin-equalisation to the diamagnetic (Ga2)IV and(In,)m ions, just as two paramagnetic hydrogen atoms form a dia-magnetic molecule.Rhenium-From the many conflicting statements in the literature,it seems established that rhenium can form three oxides, Re20,,ReO,, and ReO,.The colourless heptoxide 33 is obtained by directoxidation of rhenium. I t s m. p. (in vacuum) is 301-5", and sublim-ation begins at 220". In contrast to manganese heptoxide it issl L. M. Dennis, R. W. Work, and E. G. Rochow, J . Amr. Chm. SOC., 1934,56, 1047.IP Angew. Chm., 1934, 47, 17.8s W. Biltz and G. A. Lehrer (with K. Meisel), Nach. Gea. Wise. Qcjttingen,1931, 191; Chm. Zentr., 1932, i, 1070; A., 1932, 708; 2. anorg. Chm., 1933,214,225; A., 1933, 1259; aid., 1932,207,113; A., 1932, 1008124 INORGANIC CHEMISTRY.very stable, and this is reflected inits large heat of formation, whichis approximately 296 kg.-cals. per g.-mol.M Under certain experi-mental conditions it is possible to obtain from the oxidation ofrhenium a white crystalline product which (Frau) I.and W. Nod-dack35 assumed was the peroxide ReO, or Re208. Later experimentsby H. Hagen and A. Sieverts36 have indicated that this is not aperoxide, but possibly only another form of Re207. Accordingto W. Biltz3, and his collaborators, a red trioxide is obtained bythe prolonged action of metallic rhenium on the heptoxide a t200-250", or better, from ReO, and Re,O, at 300". The crystalstructure of this trioxide has been examined by K. Meise1,3, whofinds it to be isomorphous with tungsten trioxide, WO,. Theblack dioxide Re0,38 is formed when Re,07 and Re are heated,first a t 300" and then a t 600-650". This dioxide decomposes at1000" in accordance with the equation : 7Re0, = 3Re + 2Re207.Certain inve~tigators3~ have claimed that the red oxide is a pentoxide,Re,05, but in view of the results obtained by K.Meisel 37 this appearsunlikely. A hydrated Re2O3*0 has been prepared by the hydrolysisof rhenium trichloride with aqueous sodium hydroxide. It isreadily oxidised and will liberate hydrogen from water. A blueoxide, obtained from the reduction of Re207, has been mentioned.It may be the analogue of the well-known molybdenum-blue.In last year's report attention was directed to the isolation ofcertain halides of rhenium. 0. Ruff and W. Kwasnik41 havecontinued their investigations on the rhenium fluorides, and haveisolated pure ReF, (m. p. 18.5"; b. p. 47.6"). This is readilyreduced t o ReF, (m. p. 124-5") at comparatively low temperaturesby a variety of reagents, e.g., hydrogen a t 200", carbon monoxidea t 300", sulphur dioxide at 400".They have also establishedthe existence of ReOF, (m. p. 39-7"), Re0,F2 (m. p. 156"),and the complex fluoride K,ReF,. By contrast, the literaturedealing with the action of chlorine on rhenium is very confusing.This confusion began in 1928 with W. Noddack's statement 42 that34 W. A. Roth snd G. Becker, 2. physikal. Chem., 1932, [A], 150, I ; A., 1932,35 Naturwiss., 1929,17,93; A., 1929, 411.36 2. anorg. Chem., 1932, 208, 367; A., 1933, 43.3 7 Ibid., 207, 121; A,, 1932, 903.38 W. Biltz, ibicl., 1933, 214, 225; A., 1933, 1259.39 H. V. A. Briscoe, P. L. Robinson, and A. J. Rudge, J., 1931, 3087; A.,1932,32; W. A. Roth and G. Becker, Ber., 1932,65, [B], 373; A., 1932,353.40 W.Geilmann and F. W. Wrigge, 2. anorg. Chern., 1933, 214, 239; A.,1933, 1259.469.-Ibid., 1934, 210, 65.42 2. ElektrocJlem., 1928, 34, 627; A., 1928, 1344WARDLAW : SOME RARER METALS. 125two volatile chlorides ReCI, and ReCl, are formed when rheniumis heated in chlorine. In 1931 H. V. A. Briscoe, P. L. Robinson,and F. M. Stoddart 43 were unable to confirm this, and from theirexperiments they concluded that the primary product of heatingthe metal in chlorine was the tetrachloride ReCl,. More recently,however, W. Geilmann, F. W. Wriggo, and W. Biltz 44 report thatno tetrachloride can be isolated from this reaction, but that thepentachloride is produced and can be purified by fractional sublim-ation in a vacuum. These investigators have also prepared a redtrichloride from the dark brownish-black pentachloride by heatingit in a current of nitrogen, The analytical data 45 for this trichlorideshow that it is oxygen-free and disprove the suggestion of W.Manchot and J.J. G . F.Druce 47 claims to have prepared trimethylrhenium from thetrichloride. Although a hexafluoride and a pentachloride of rheniumare now known, the highest bromide so far prepared is the tri-bromide, which H. Hagen and A. Sieverts48 have isolated as agreenish-black sublimate by heating rhenium at 500" in brominevapour. It is noteworthy that when the different compounds sofar isolated are arranged in the order of their highest valencies,the series becomes RezO,, Rep,, ReCl,, ReBr,.This is quitein accordance with the general rule that, for a given element, in theseries oxides, fluorides, chlorides, bromides, etc., the tendency toreach the highest possible valency decreases.The salts of per-rhenic acid offer some marked contrasts to thepermanganates. For example, the colourless Re,O, dissolves inwater to produce a colourless solution of per-rhenic acid, which formscolourless salts with the alkali and alkaline-earth metals. Inaddition, an investigation by E. Wilke-Dorfurt and T. Gunzert 49has revealed striking differences in solubility, crystal form, and con-tent of water of crystallisation between the per-rhenates and thecorresponding salts of permanganic, perchloric, and hydrofluoroboricacids. Per-rhenates of the type M'RO, are generally referred to asmeta-salts, for with excess of base it is possible to isolate yellowmesoper-rhenates, MiReO,.The barium salt Bas(ReO6),, whichhas been fully is decomposed by water into Ba(OH),that it might be Re,Cl,O.43 J., 1931, 2263; A., 1931, 1255.44 2. anorg. Chem., 1933,214,244; A., 1933, 1259.45 W. Biltz, W. Geilmann, and F. W. Wrigge, Annalen, 1934, 511, 301 ; A.,4 8 Ibicl., 500, 228; A., 616.4a 2. anorg. Chem., 1933, 215, 111; A., 1934, 44.49 Ibid., p. 369; A., 1934, 158.979.4 7 J., 1934, 1129; A., 995.(Frau) I. and W. Noddack, ibid., p. 129; A., 1934,44; B. Schasnow, ibid.,11. 185; A., 44126 INORUANIC CHEMISTRY.and Ba(ReO,),. A number of similar compounds containingrhenium of lower valency have been reported, but their identityis not yet fully established in every case.A brown rhenite,Na,ReO,, is known, and an unstable sand-yellow hyporhenate,possibly Na4Re20,, as well as an unstable green rhenate, BaRe04,have been recorded by (Frau) I. and W. N~ddack.~oThe stable sulphide of rhenium is the black disulphide, ReS2.51A black hydrated sulphide, Re2S,, is precipitated when hydrogensulphide or sodium thiosulphate reacts with potassium per-rhenate,but this is converted into the disulphide when heated in a currentof nitrogen. 52Some interesting results have been obtained by the electrolyticreduction of acid solutions of rhenium compounds. Reduction ofKReO, in 9N-hydrochloric acid, with either a bright or a platinisedplatinum cathode, gives a green solution containing quinquevalentrhenium.53 An olive-green solution of tervalent rhenium is obtainedby cathodic reduction of K,ReCl, in 2N-sulphuric acid.54 Theseresults are very similar to those obtained with molybdenum com-pounds, and further work on these electrolytically reduced solutionsshould yield valuable information about rhenium derivatives.Finally, it may be mentioned that rhenium forms a number ofco-ordination compounds displaying covalencies of four and six,e.g., PyH[ReBr,], K,[ReOC15],H,0, X2[ReC1,], X,[ReBr,], whereX = K, Rb, Cs, etc., and that various oxychlorides and oxybromidesare known.The chemistry of rhenium is much more complicatedthan this short sketch might lead one to suppose, but this state-ment can be fully confirmed by reference t o “Das Rhenium”(Leipzig, 1933) by I.and W. Noddack. w. w.5 . THE CORROSION OF METALS.Progress in research on the corrosion of metals has not beenreviewed in these Reports during recent years, although occasionalreference to results of particular interest has been made. Thepresent Report does not cover any specific period, therefore, butaims at reviewing the trend of research. Space does not permit ofthe discussion of all the aspects of this work; some of the morefundamental directions of research have been followed a t theexpense of leaving a certain amount of interesting work unmen-tioned. A feature of modern views on corrosion is the recognitionI. R. Juza and W. Biltz, 2. Elektrochem., 1931, 37, 498;’ A., 1931, 1128.52 W.Biltz and F. Weibke, 2. anorg. Chem., 1931, u)3, 3; A., 1932, 238.63 W. F. J a b and B. Jeiowska, W., 1933, 214, 337; A., 1933, 1254.W. Manchot and J. Dihing, Zoc. cit., ref. (46)HEDGES : THE CORROSION OF METALS. 127of the imporfant part played by films, especially those of a pro-tective nature. In order to emphasise this aspect, the results arepresented in a somewhat different order from that usually followed.Film Formation and Passivity.Progress in the study of passivity, whilst of primary importancefrom the theoretical viewpoint of corrosion, is one part of the fieldof corrosion in which considerable unanimity of outlook amonginvestigators all over the world has been reached. Although all arenot agreed as to the mechanism, yet it is now generally acceptedthat passivity is due to the presence of a protective film, generally,but not necessarily, of oxide.Air-formed PiZms.-The existence of air-formed oxide films, whichinterfere with the reactivity of the underlying metal, has beendefinitely established for copper,f aluminiumY2 irony3 and certainother metals.Reference has been made in a previous Report to theisolation of the air-formed protective film on iron. These films havesince been subjected to further study, particularly with regard tothe conditions of their breakdown and their structure. U. R. Evanshas shown that breakdown of the protective oxide film on iron,steel, zinc, or aluminium tends to occur where the specimen hasbeen bent or otherwise distorted.Corrosion occurs preferentiallya t the bend, especially on the convex side.U. R. Evans and J. Stockdale 6 have put forward a scheme repre-senting the structure of the surface film. This is pictured in fourzones : (u) an outer zone of oxide, (b) a zone containing oxide andmetal having a high resistance to attack, ( c ) a shattered zone,fairly free from oxide and having a low resistance to attack, and(d) the unchanged metal. They have also devised an improvedelectrolytic method of isolating the film, by dissolving away ( c ) .Flakes of iron oxide, thus isolated from iron heat-tinted to the first-order yellow, were found to have a thickness corresponding with2 x lo4 g. of ferric oxide per sq. cm., agreeing with F. H. Con-stable's ' determination of the thickness of the film on yellow-tintediron (0.46 x cm.).Passivation in Concentrated Nitric Acid.-Although it has notbeen possible to isolate an oxide film from iron which has beenimmersed in concentrated nitric acid, yet this classical example of1 W.H. J. Vernon, J., 1926, 2273; A., 1926, 1108 ; F. H. Constable,Nature, 1929, 123, 569; A., 1929, 503.a H. Sutton and J. W. W. Willstrop, J . Inst. Metals, 1927, 38, 259; U. R.Evans, J., 1927, 1039; A., 1927, 610.a Idem, ibid., p. 1021; A., 1927, 619.6 J., 1929, 92 ; A., 1929, 270.4 Ann. Reports, 1928, 25, 30.6 Ibid., p. 2661 ; A., 1930, 29.Proc. Roy. SOC., 1928, [A], 117, 376; A., 1928, 106128 INORGANIC CHEMISTRY.passivity has been brought into line with the oxide-film theory, forE.S. Hedges 8 obtained convincing evidence of the existence of afilm of ferric oxide. Shortly afterwards, C. Benedicks and P. Seder-holm 9 examined the effect of dilute alcoholic nitric acid solutionson carbon steels. Owing to the relatively slight dissociation ofnitric acid in alcohol, these solutions have something in common asan oxidising agent with concentrated aqueous solutions of nitricacid, and they were shown to render the steel passive and to producea film of ferric oxide, which was actually photographed. Thecritical concentration of nitric acid required to render iron and steelpassive has been reinvestigated by Y. Yamamoto.1° Hedges hasalso shown that other metals are rendered completely passive inconcentrated nitric acid a t - ll", and that copper l1 acquires anoxide film in concentrated nitric acid at ordinary temperatures,the existence of which is the cause of the practically completeinertness of this metal when it is kept in motion in this reagent.A.Kutzelnigg l2 has described the passivity of copper in a mixtureof nitric and sulphuric acids.Activating E8ect.s of 1ons.The activating influence of certainanions (especially chlorides) on passive metals has been studied, butit is not yet possible to state definitely whether the effect is due topenetration of the oxide film by anions of small size or whether theactivation is related to the well-known peptising effect of chlorides,thus loosening the protective film. The activating effect has beenstudied 13 by measuring the potential of the metal in the solutionagainst a standard reference electrode.S. C. Britton and U. R.Evans 1* have measured the penetrating powers of different anionsby determining the leakage current at an aluminium anode in asolution of potassium chromate, to which solut4ions containing theions investigated were added. The following decreasing sequenceof penetrating power was noted : chloride> bromide>iodide>fluoride>sulphate>nitrate>phosphate. These results have beenconfirmed by L. Tronstad and B. W. Bommen.15 In general, theactivating power decreases with increasing size of the anion, but it8 J., 1928, 969; Ann. Reports, 1928, 25, 30.9 2. physikal. Chem., 1928,138, 123; B., 1929, 21.10 Bull.Imst. Phys. Chan. Rm. Japan, 1934, 13, 375; A., 1934, 736.11 E. S. Hedges, J., 1930, 561; A , , 1930, 649.1 2 2. Elektrochem., 1933, 39, 67; A , , 1933, 365.13 A. L. McAulay and S. H. Bastow, J., 1929, 85; A., 1929, 270; U. R.Evans, ibicl., p. 92; A., 1929, 270; E. S. Hedges, ibirE., p. 1037; A., 1929,776; T. P. Hoar and U. R. Evans, J. Iron and Steel Inat., 1932, 26, 379;A., 1932, 989.14 J., 1930, 1773; A., 1930, 1258.l6 K . Norske Vidensk. Selsk., 1933, 45, 174HEDGES: THE CORROSION OF METALS. 129may be pointed out that a similar rule holds roughly for peptisation.A comparison of the activating effects of various anions on a passivemetal with the peptising effect of the same anions on the hydroxide.of the metal would be of much interest.The comparative feebleness of the fluoride ion in penetratling orloosening the protective oxide film on iron has been confirmed byA.W. Chapman.16 I n activating passive chromium by cathodicpolarisation, E. Muller and K. Schwabe l7 have shown that adefinite activation potential is required in different acid solutions,the negative potential increasing in the order : hydrochloric,hydrofluoric, hydrobromic, sulphuric, perc hloric, ort hophosphoric .The small ions are thus the most powerful. These authors haveput forward the view that chromium in the passive state is coveredby a network of chromic oxide molecules, anchored to the units ofthe chromium space lattice. As the cathodic polarisation isincreased, the small hydrogen ion is dragged through the oxidenetwork and the electrostatically-bound anion, if it is not too large,can follow it and dissolve the film.Activation is favoured atcorners and edges of the metal, because there the oxide network islooser. A short-circuited cell is then set up, and if the potentialreaches a higher negative value than the activation potential forthe particular acid, the whole metal will become active. Withchromium a t 20" this is realised only in hydrochloric acid.Anodic Films.-During the last five years or so a great amount ofwork on anodic passivity has been carried out by W. J. Muller 18l6 J., 1930, 1546 ; A., 1930, 1128.1 7 2. Elektrochem., 1931, 37, 185; A., 1931, 571; E. Muller, 2. physikd.Chem., 1932, 159, 68; A., 1932, 473.18 W.J. Muller, 2. Elektrochem., 1927, 33, 401; A., 1928, 135; Monatsh.,1927, 48, 61; A., 1927, 735; ibid., p. 559; A., 1927, 1145; 2. Elektrochem.,1928, 34, 571; A., 1928, 1319; ibid., p. 850; A., 1929, 270; ibid., 1929, 35,ibid., 1930,56, 191; A., 1930, 1527; 2. Elektrochem., 1930, 36, 550; A., 1930,Trans. Paraday SOC., 1931, 27, 737; A., 1932, 25; Korrosion U. Metallschutz,1932, 8, 253; A., 1933, 576; Trans. Paraday Soc., 1932, 28, 471; A., 1932,576; Z. Elektrochem., 1932, 38, 850; A., 1933, 30; Angew. Chem., 1933, 46,197; A., 1933, 468; Korrosion u. Metallschutz, 1934, 10, 1; A., 1178; Natur-wisa., 1934,22, 479; A., 968; 2. Elektrochem., 1934, 40, 119, 536, 578; A., 602,1072 ; W. J. Miiller with E. Noack, Monatsh., 1927,48,293 ; A., 1927,942 ; withK.Konopicky, ibid., p. 711 ; A., 1928,247; with 0. Lowy, ibid., 1928, 49, 47;A., 1928,713; with K. Konopicky, ibid., 1928, 50, 385; A., 1929,146; idem, 2.Ekktrochem., 1928,34, 840; A., 1929, 269; idem, ibid., p. 858; A., 1929, 146;idem, Z. physikal. Chern., 1929, [A], 141, 343; A., 1929, 770; with 0. Lowy,Monatsh., 1929, 51, 73; A., 1929, 402; with K. Konopicky, ibid., 1929, 52,289; A., 1929, 1241; with L. Holleck, ibid., 1929,52,409,425; A., 1930, 298;with K. Konopicky, ibid., p. 442, 463; A., 1930, 298; with W. Machu, ibid.,REP .-VOL. XXXI. E93, 656; A., 1929, 270, 1393; Momtsh., 1929, 52, 53, 221; A., 1929, 886;1257; ibid., p. 679; A., 1930, 1377; ibid., 1931, 37, 328; A., 1931, 915i30 1NORGANIC CHXMISTRY.and his collaborators in Vienna.This important wcrk has notpreviously been described in these Reports.An essential feature of the experimental conditions is the elimin-ation of disturbances a t the anode due to convection. By using ahorizontally disposed anode, sheltered from such disturbances, thereaction products remain where they are formed and their propertiescan be observed. Under these conditions, current density-potentialcurves for different anodes in various solutions can be made repro-ducible, and .the value determined at which the potential suddenlyrises,One of the most striking results of the work, which appears in theearlier papers, is the complete demonstration that the time duringwhich the current must flow before passivity sets in depends on thecurrent density; passivity can be brought about either by a smallcurrent acting for a long time or by a heavy current acting for ashort time. This relation suggests that the accumulation of somereaction product a t the surface of the anode is responsible forpassivity.For a typical case, such as the anodic treatment of ironin dilute sulphuric acid, the view developed is that some product(in this case ferrous sulphate) accumulates a t the surface of the anodeuntil the solution in the vicinity becomes supersaturated, whereupona solid crystallises on the anode surface. The deposit covers a largeportion of the surface, increasing the effective current density atthe uncovered portions to perhaps 100 or 1000 times the originalvalue. The film is not identified with the protective film causingpassivity, but, by screening a large area of the electrode, it maylead to conditions which cause true passivity.Muller calls the firststage " Bedeckungspassivitat " and the second stage " chemischePassivitiit .' 'To elucidat,e the relation between the two stages, the rate of fallof current with time has been studied, whilst the composition of thefilm responsible for " Bedeckungspassivittiit " has been confirmedin some cases by direct observations with the polarising microscope.In fairly concentrated acids, the films appear to be normal salts,but in more dilute solutions they may consist of basic salts or evenoxides or hydroxides.Assuming that the thickness of the deposited layer remainsp. 474; A., 1930, 298; idem, 2.physikal. Chem., 1931, Bodenstein Festband,p. 687; A., 1931, 1238; ibid., 1932, [ A ] , 161,147,411; A., 1932, 993,1208; withH. K. Cameron and W. Rlachu, Monatsh., 1932, 59, 73; A., 1932, 343; with w. fixachu, ibid., 1932, 60, 359; A., 1932, 1000; with E. Low, 2. Elektrochem.,1933, 39, 872; A., 1934, 33; with W. Machu, 2. physikal. Chem., 1933, [A],166,357; A., 1934,33; Monateh., 1933,63, 347; A., 1934,368; with E. Low,2. Elektrochem., 1934,40, 570; A., 1072HEDGES: THE CORROSION OF METALS. 131constant and that the film grows sideways only, the fall of thecurrent i with the time t is given by the expressionwhere i, is the initial current, i, the residual current, and C and Aare constants defined by the formula?SS2Kk(1 - u)wo C = "' and A = k(1 - u)i,s being the specific gravity of the film material, 6 the thickness,P the original area of the anode surface, k the electrochemical con-stant, u the anionic transport number, wo the resistance from thecathode to the boundary layer adjacent to the anode, and K theconductivity of the solution in the boundary layer.The sideways-growth relation has been confirmed experimentallyin sulphuric acid as the electrolyte for anodes of copper, and alsofor those of iron or nickel in the early stages.In the later stagesof anodic passivation, the last two metals follow a course whichcan be related to the growth of a film in thickness, without sidewaysextension. Then the currents i, and i, passing at times t, and t,are in accordance with the formulat , - t , = B(l/iI2 - 1/i22)where B is a .constant depending on the area uncovered.Thisrelation has been confirmed experimentally also for anodes of zinc,chronium, and lead.In the later papers of the series, Miiller definitely accepts theexistence of a protective film at passive anodes, but maintains that,when the metal can exist in more than one state of valency, theformation of the film is preceded by an electronic change in themetal. Thus, with an iron anode in dilute sulphuric acid," Bedeckungspassivitat " is due to the primarily-formed film offerrous sulphate; at unprotected spots, subject to a very highcurrent density, a change is brought about which induces the metalto go into solution as ferric ions; the product is easily hydrolysed,and forms a protective film of ferric oxide on the anode (" chemischePassivitat ").With aluminium, where no change of valencyoccurs, the whole process is regarded as " Bedeckungspassivitat ."Whether the change of valency observed with some metals is primaryor secondary, there is clearly agreement here that anodic passivity,like other forms of passivity, is characterised by the formation of aprotective film.Recent researches have examined quantitatively the degree ofprotection afforded by the film. Like previous investigators, wh132 INORGANIC CHEMISTRY.have discussed the problem only qualitatively, Muller regards thefilm as containing pores; the finer the pores, the more protectiveis the film. He has shown quantitatively how the potentialassumed by the metal is related to the number and size of thesepores. Qualitatively, the greater the number of pores and thelarger their size, the closer the potential approaches that of theunderlying metal ; on the other hand, when the pores are sufficientlysmall, corrosion no longer occurs.Thus, the activating influence ofchlorides is traced to the relative ease with which such small anionscan travel through the pores of the film, whilst larger anions, suchas sulphate and phosphate, can penetrate the pores only withdifficulty. A film may be efficiently protective, therefore, in solu-tions containing large anions, but not in solutions containing smallanions.Many of Miiller’s observations are confirmed by the contem-poraneous work of E.S. Hedges l9 on the formation of anodic filmson copper, silver, magnesium, zinc, cadmium, mercury, tin, lead,iron, cobalt, nickel, and aluminium. Tbe conditions of study weresuch that the film automatically appears and disappears periodically,and were thus peculiarly favourable for the study of film formation.I n many cases, two definite stages in passivation, corresponding ingeneral with those postulated by Muller, could be observed directlyin each recurrent period.The conditions for periodic anodic film formation or passivityhave been elucidated. The experiments show that periodicpassivity is simply a special case of periodic film formation, inwhich the film is highly protective, and that passivity is a generalproperty exhibited to various extents by all metals under suitableconditions, and to different degrees depending on the protectiveproperties of the film under the particular conditions prevailing.The work has led t o a general theory of anodic polarisation,which is confirmed by experiments on the influence of speed ofrotation of the anode on periodic anodic passivity, and receivessome support from the work of U.R. EvansY20 who has isolatedthe film responsible for the passivity of an iron anode in dilutesulphuric acid.E. Muller and K. Schwabe 21 have studied the formation of filmson anodes of zinc, cadmium, lead, and copper in saturated andunsaturated solutions of their salts. Complete passivity is neverproduced in these systems.1s J., 1926, 1533, 2580, 2678; 1927, 1077, 2710; 1928, 969; 1929, 102820 Nature, 1930, 126, 130; A., 1930, 1126.21 2.Elektyochena., 1932, 88, 407; A., 1932, 814.A., 1926, 807, 1213; 1927 85, 630; 1928, 23, 600; 1929, 775HEDGES : THE CORROSION OF METALS. 133The formation of films in the dissolution of nickel anodes in acidand salt solutions has been studied by I<. Georgi.22 The potentiala t low current densities is higher the greater the size of the anionin the series chloride, bromide, sulphate, chlorate. Three statesare recognised. The active state is favoured by low currentdensity, small anion, high hydrogen-ion concentration, and hightemperature ; the reverse conditions favour an impoverished diffusionlayer next to the anode and cause transition to a state of higherpotential.At the lowest current densities, nickelous ions enter thesolution at certain active centres, and hydrogen collects on thegreater portion and may be removed by depolarising influences.The second state is characterised by an invisible film of nickelichydroxide, and the third by a porous diaphragm of the samehydroxide. Georgi obtained similar results with ancdes of cobaltand ir0n.~3The passivity of copper anodes in sulphuric acid24 and of goldanodes in hydrochloric and sulphuric acids25 has been traced tothe formation of oxide or similar films. The mechanism of theanodic passivity of gold in chloride solutions has been furtherstudied by G. Armstrong and J. A. V. Butler.26 The nature of theanodic oxide film formed on aluminium in oxalic acid has beeninvestigated by S.Setoh and A. Mi~ata.~'Optical and Other Means of Investigation.-The air-formed filmhas been recognised by optical means by H. Freundlich, G. Pat-scheke, and H. Zocher,28 who prepared mirrors of pure iron by thethermal decomposition of iron pentacarbonyl in absence of air.When air was admitted, a fall in the reflecting power of the mirrorswas observed, and the chemical reactivity of the iron was reducedsimultaneously .L. Tronstad 29 has applied the optical method to the examinationof anodic passivity, and shown that the optical constants of nickeland iron rendered passive in sodium hydroxide solution, and ofnickel rendered passive in sulphuric acid solution, undergo a change22 2.Elektrochem., 1932, 38, 681, 714; d., 1932, 1000, 1093.23 Ibid., 1933, 39, 209, 745; A , , 1933, 468, 1016.24 M. Lignana, Nature, 1932, 130, 474; A., 1932, 1208.25 W. J. Shutt and A. Walton, Trans. Fayaday SOC., 1932, 28, 740; A.,1932, 1209; ibid., 1933, 29, 1209; A., 1933, 1242; ibid., 1934, 30, 914; A.,1178.26 Ibid.,p. 1173.27 Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1932, 19, 189, 237; A., 1933,28 2. physikal. Chern., 1927, 128, 321; 130, 289; A., 1927, 1037, 1149.29 Nature, 1929, 124, 373; A., 1929, 1150; 2. physikal. Chem., 1929, 142,241 ; A., 1929, 1002 ; K . Norske Vidensk. Selsk., 1931, No. 1 ; Nature, 1931,127, 127; A,, 1931, 301; Trans. Paraday SOC., 1933, 29, 502; A., 1933, 469.29, 1254134 INORGANIC CHEMISTRY.resembling that observed when a clean iron surface is broughtfrom a vacuum into contact with air.This result points directlyto the formation of an oxide film during anodic passivation.L. Tronstad and C. W. Borgmann30 have shown by the opticalmethod that when iron, steel, or stainless steel is immersed inpotassium chromate solution or concentrated nitric acid, thenatural, air-formed films are strengthened or even replaced bydenser films, in accordance with the oxide theory of passivity.Approximate calculations give 100 8. for the thickness of the oxidefilm formed on steel in nitric acid, and 30-40 8. for that formed ina chromate-chloride solution. The thickness of the film on stainlesssteel in concentrated nitric acid was only 10 A. Similar experimentsindicate that the natural oxide film on aluminium 31 has a thicknessof 100 A.and undergoes only small changes in chromate solutions.The optical method also shows 32 that in dry ozone highly protectivefilms are obtained on silver, iron, and ordinary and stainless steels,whereas less protective films are acquired by copper and zinc. Inmoist ozone, no highly protective films are produced.On the whole, relatively litltmle help has been gained by the applic-ation of X-ray and electron-diffraction technique to the elucidationof the structure of the film. F. Mriiger and E. Nahring33 obtainedidentical X-ray diagrams for active and passive iron, nickel, andchromium in the finely-divided condition, and considered that anyoxide film present could not be thicker than lo-' cm.Actually,there is no reason why a really continuous protective film needexceed lo-' cm. in thickness ; moreover, in some cases the film maynot have a crystalline space-lattice.G. P. Thomson 34 has found no difference in the electron-diffractionpatterns of active and passive iron; but it should be pointed outthat neither aluminium covered with the usual air-formed film, norlead, freshly cut and heated in the air a t about loo", gave a diffractionpattern in his experiments. J. A. Darby~hire,~~ however, afterisolating the oxide films on heat-tinted nickel and copper by Evans'smethod, has demonstrated their crystalline nature by the electron-diffraction method. The spacings obtained indicate the formulieNiO and Cu,O for these oxides.The electron-diffraction patternof iron rust has been obtained by J. Cates.36 C . A. Murison373O Trans. Faraday SOC., 1934,30, 349; A., 486.31 L. Tronstad and T. Hoverstad, Trans. Paraday SOC., 1934, 30, 362; A.,32 Idern, ibid., p. 1114.34 Proc. Roy. SOC., 1930, [A], 128, 649; A., 1030, 1082.86 Trans. Faraday SOC., 1931, 27, 675.36 Ibid., 1933, 29, 817; A., 1933, 1022.37 Phil. Mag., 1931, [vii], 17, 96; A., 134.486.33 Ann. Physik, 1927, 84, 939HEDGES: THE CORZOSION OF METALS. 135has found that surface films on copper heated in air give diffracticnpatterns for cuprous oxide and a new form of cupric oxide. Dif-fraction patterns have been obtained from oxide films on zinc byG. I. Finch and A. G. Q ~ a r r e l l .~ ~Corrosion in Aqueous Xolutions.Neutral Media.-A vigorous campaign to determine the mechan-ism of the corrosion of metals in neutral aqueous solutions has beenmade during the last few years by Bengough and his collaborator^.^^The work has aimed at acquiring quantitative data for the extentand nature of corrosion under different conditions, and has beenconcerned especially with the corrosioii of zinc and mild steel inneutral salt solutions, such as potassium chloride, over a wide rangeof concentration. Special attention has been devoted to repro-ducibility of the results. The influence of various factors, such asconcentration, depth of immersion of the specimen, convection,access of oxygen, purity and treatment of the metal, and natureof its surface, has been studied, and it has been possible in manycases to ascertain which is the controlling factor in a given set ofcircumstances.Two types of corrosion have been recognised,corresponding with evolution of hydrogen and absorption of oxygen.Concurrently with the kinetic measurements, the course anddistribution of corrosion have been followed by microscopicalobservation. It is held that certain of the results cannot beaccounted for by the differential aeration theory. The initialbehaviour of zinc, when placed in a salt solution which does notform a passivating film, is to displace hydrogen a t numerous points.The possibility of the production of gaseous hydrogen being neglected,a polarising layer is formed a t the metal surface.The oxygenpresent is required for depolarisation; if the anions present form asoluble salt with the metal and are plentiful, corrosion proceeds a ta rate which is directly proportional to the oxygen supply.When zinc corrodes in solutions of potassium sulphate or chloridein presence of oxygen, the film of zinc oxide formed is in partscontinuous; impermeable to oxygen, and closely adherent to themetal, and in parts in the form of " domes," which are loose andpermeable to oxygen. Corrosion is most serious under the" domes." The authors point out that, if the protective type ofhydroxide film is formed over a part of the metal, corrosion can88 Proc. Physical Soc., 1934, 46, 148 ; p., 352.39 G. D. Bengough,,J. M. Stuart, and A. R. Lee, Proc.Roy. Soc., 1927, [ A ] ,116, 451; A,, 1928, 250; ibid., 1928, [ A ] , 121, 88; A., 1928, 1333; ibid., 1930,[A], 127, 42; A., 1930, 712; G. D. Bengough, A. R. Lee, and F. Wormwell,ibid., 1931, [A], 131, 494; A., 1931, 691; ibid., 1931, [A], 134, 308; A., 1932,27 ; G. D. Bengough and F. Wormwell, ibid., 1933, [A], 140,399; A., 1933,679136 INORUANIC CHEMISTRY.only occur elsewhere ; they maintain that the preferential corrosionunder the " domes " is not due to potential differences set up bydifference of oxygen concentration, but to the fact that ions canfreely enter solution there. Other portions of the metal surfaceare prevented from undergoing local dissolution by the protectivefilm, which, however, allows depolarisation of hydrogen displacedby metal entering the solution elsewhere.According to the " film-distribution " theory advanced, dissolvedoxygen is not really an inhibitor of corrosion, but a stimulator ; itmay act as a local inhibitor owing to the formation of secondaryproducts, which prevent access of oxygen to the underlying metaland the entrance of ions into solution, but corrosion is propor-tionally increased elsewhere.Thus, corrosion distribution isdetermined mainly by the distribution of protective films, whichcause the metal to be locally cathodic to bare, or less completelyprotected, metal. When the films are widespread, corrosion maybe sufficiently localised to be called " pitting." Among the factorsinfluencing the character, distribution, and continued adherence ofthe films are distribution of alkali, surface tension, presence ofspecially reactive areas, gravity, movement of liquid, alternate wetand dry conditions, the presence of foreign substances, and thenature of the solution.Simultaneously, Evans and his collaborators 40 have continuedresearches the results of which support the differential aerationtheory, some of the systems investigated being similar to thoseexamined by Bengough and his colleagues.It has been shownthat, under conditions favouring the complete tapping of theelectric currents flowing between the anodic and cathodic portionsof the corroding metal, the currents measured are equivalent to thecorrosion occurring, both when the anodes and cathodes are ofdifferent metals and when the anodic and cathodic areas of the samemetal are determined by differences in oxygen concentration.Theproblem of corrosion velocity is thus resolved into a study of theelectrochemical factors which determine the strength of the current.It is pointed out that the experiments of Bengough and his co-workers have been carried out under conditions which reduce thepossibility of differential %ration to the minimum.The objections of the Bengough school to the differential-aerationtheory are further answered by C . W. Borgmann and U. R. Evans 4 1in a paper describing work on the corrosion of zinc in chloride solu-40 U. R. Evans, L. C. Bannister, and S . C . Britton, Proc. Roy. Soc., 1931,[A], 131, 355; A., 1931, 691; U. R. Evans and T.P. Hoar, ibid., 1932, [ A ] ,137, 343; A,, 1932, 1003.4 1 Trans. Amr. Electrochem. SOC., 1934, 65, 249EEDGTES: THE COR,ROSION OF METALS. 137tions. There, it is shown that different results are obtained accord-ingly as the specimens are partly or wholly immersed in the solution.The apparent discrepancy between the results obtained with half-immersed sheet zinc and Bengough’s results with totally immersedzinc is traced to the avoidance of oxygen starvation in the partly-immersed specimens.U. R. Evans and R. B. M e a r ~ , ~ ~ replying to further criticisms byBengough, agree that the film-distribution theory and the differential-=ration theory have much in common, which is concealed by themode of presentation; in particular, the views agree in ascribingprotection largely to the cathodically-formed alkali.Differences ofopinion exist as to the effect of solid corrosion products on oxygentransport, and the possible inhibition of corrosion by excess ofoxygen. Further work in support of both the theories of differentialaeration and film distribution will be awaited with great interest;to many who are following the work it may appear that the twoschools of thought are by no means irreconcilable.In a study of the effect of non-metallic inclusions on the corrosionof mild steels, C. E. Homer 43 has shown that under mildly corrosiveconditions (e.g., in tap water, distilled water, etc.) sulphide andscale inclusions determine the initial points of attack. Only a smallproportion of such inclusions has any effect, however, and inclusionsof silicates or alumina are inactive. The action appears to beconnected closely with the breakdown of the protective oxide film.No evidence was obtained that either sulphide or scale inclusionsact as cathodes in the corrosion process.Under conditions favouringpitting, the initial breakdown may determine the sites of pitting.Similar conclusions have been reached by L. Tronstad and J.Sejer~ted,~4 who have investigated the effect of sulphur andphosphorus on the corrosion of iron.J. N. Friend and W. West45 have shown that the addition ofcopper up to 3.70% increases the resistance of nickel steel to alternatewet and dry sea action. F. Todt 46 has studied the influence ofoxidising and reducing agents on the corrosion of iron in bufferedsolutions.The corrosion of tin, tin-antimony , and tin-antimony-copper alloys in various tap-waters has been described byT. P.42 Proc. Roy. SOC., 1034, [A], 146, 153; A., 1181.43 Iron and Steel Inst., Cmnegie Schol. Memoirs, 1932, 21, 35; Special44 J . Iron and Steel Inst., 1933, 127, 425.4 5 Ibid., 1931,123, 501; B., 1931, 637.46 2. Elektrochem., 1934, 40, 536; A., 073.4 7 J . Inst. Metals, 1934, 55,135.Report No. 5, 1934, 225138 INORGANIC CHEMISTRY.The theory of the corrosion of metals has been discussed 48 andsome new views have been put forward. E. S. Hedges49 has out-lined a, theory involving primary reaction of the metal withwater molecules, the extent of the corrosion depending on the degreeto which the initially formed hydroxide film is dissolved or peptisedby the solution, and almost simultaneously A.L. McAulay andE. C. R. Spooner 50 have advanced the view that electrode potentialmust originate in interaction between the metal and water only.U. R. Evans and T. P. Hoar 5l have discussed the mechanism ofcorrosion in the light of both cathodic and anodic processes, andhave emphasised the important r61e of the relative solubility of thereaction products.The Dissohtion of Metals in Acids.-In the course of work on thedissolution of sodium amalgam in weak acid solutions, J. N.Bronsted and N. L. R. Kane 52 discuss the wider aspects and concludethat the dissolution of a pure metal in an acid is probably the resultof a chemical reaction between an electron of the metal and amolecule of the acid.G.Tammann and F. Neubert 53 have found that the rate of evolu-tion of hydrogen from dilute acids when acted on by zinc, iron, oraluminium can be expressed by v = a t + b t2, where v is thevolume liberated a t the time t . The constant a is characteristicof the metal and is unaffected by impurities, whilst the constant brepresents the accelerating influence of heterophase impuritiesforming local electrolytic cells.The velocity of the dissolution of zinc in acids has been thesubject of several papers. E. Miiller and J. Forster 54 have studiedparticularly the influence of the concentration of the acid and thenature of the anion. M. Centnerszwer and M. Straumanis 55 haveshown that electrolytic zinc dissolves much more slowly in dilutesulphuric acid than in hydrochloric acid of the same hydrogen-ionconcentration.The velocity of dissolution is related to the con-centration (C) of hydrochloric acid (up to 2N) by the linear equationdv/dt = k(C - Co), where Co is the threshold concentration of acidat which dissolution begins, and k is a constant. The value of thetemperature coefficient and the influence of stirring confirm that4a M. Stremanis, Korrosion u. Metallschutz, 1933, 9, 1, 29; 0. P. Watts,Trans. Arner. Electrochem. SOC., 1933, 64, 219; A., 1933, 1122.49 “ Protmtive Films on Metals,” London, 1932, p. 165.bo Proc. Roy. Soc., 1932, [ A ] , 138, 494; A., 1933, 28.51 Tram. Faraday SOC., 1934, 30, 424; A., 606.5a J .A m r . Chem. SOC., 1931, 53, 3624; A., 1931, 1373.sa 2. anorg. Chem., 1931, 201, 225; A., 1932, 128.b4 2. Elektrochem., 1932, 38, 901; A., 1933, 130.5 5 2. physikal. Chem., 1931, [ A ] , 167, 421; A., 370HEDGES : THE CORROSION OF METALS. 139the velocity of this reaction is controlled by the chemical process,not by the diffusion of the acid. The dissolution is preceded byan induction period, which can be eliminated by previously rubbingthe zinc with emery paper.56 The influence of various addenda,especially hydrophilic colloids, on the rate of dissolution of zincand iron in hydrochloric acid has been investigated by M. Schun-bert.57 0. Bauer and P. Zunker 58 have studied the influence ofsmall quantities of alloying elements on the rate of dissolution ofzinc in hydrochloric acid, and shown that the results are not neces-sarily parallel with those obtained in neutral salt solutions.L.Whitby 59 has found that, whilst the rate of dissolution of99-90 yo magnesium in 0-05N-hydrochloric acid is independent ofthe impurities in the metal, large variations are observed fordifferent samples in sodium chloride; these are traced to the effectof films formed at the cathodic parts of the surface, whilst in theacid solutions film formation is prevented. The rate of dissolutionof magnesium in dilute acids has also been studied by M. Elpatrickand J. H. Rushton,Go who direct attention to the part played bywater. R. Muller 61 concludes, from measurements of the velocitycoefficient of the dissolution of aluminium with hydrochloric acid,that the reaction occurs with HCl-H,O complexes.The Corrosion of Tinp7ate.-The use of tinplate as a food containerhas encouraged considerable activity during recent years in theinvestigation of the conditions of corrosion of tin, iron, tinplate,and the tin-iron couple in various aqueous solutions, notably thoseof weak acids.The existence of discontinuities in the tin coatingof tinplate might be expected to lead to serious local corrosion a tthe exposed steel. Experiments 62 have shown, however, thatunder certain conditions the potential of the tin-iron couple isreversed, tin becoming anodic to iron. Under these conditions theattack is not localised at small areas, and the tinplate gives moreuseful service.Different explanations of this phenomenon havebeen advanced, the reversal of potential being ascribed to filmformation on one or both of the metals, or to the high hydrogenoverpotential of tin. T. P. Hoar 63 states that tin is anodic to iron56 2. physikal. Chem., 1934, [ A ] , 167, 421 ; A., 370.67 Ibid., 1933, [A], 157, 19.59 Trans. Paraday Soc., 1933, 29, 415, 853 ; A., 1933, 233, 1017.60 J . Phys~cuZ Chem., 1934, 38, 269; A., 605.61 2. Elektrochem., 1934,40, 126; A., 605.62 C. L. Mantel1 and W. G. King, Trans. A ~ W . Electrochem. Soc., 1927, 51,40; B., 1927, 632; R. H. Lueck and H. T. Blair, ibid., 1928, 54, 257; B.,1928, 819; E. F. Kohman and N. H. Sanborn, Ind. Eng. Chem., 1928, 20, 76,1373; B., 1928, 159.68 2.Metallk., 1933, 25, 282.63 Trans. Furaduy Soc., 1934,30, 472; A., 735140 INORGANIC CHEMISTRY.in citric and oxalic acid solutions, owing to the removal of tin ionsas complexes, whilst in dilute sulphuric acid, where such complexesare not formed, tin remains cathodic to iron.An improved method of detecting discontinuities in the tincoating of tinplate, by observing the sites of rust formation whenthe carefully cleaned specimen is immersed for some hours in hotdistilled water within a certain p H range, has been described byD. J. Macnaughtan, S. G. Clarke, and J. C. P r y t h e r ~ h . ~ ~T. N. Morris and J. M. Bryan 65 have undertaken a systematicinvestigation of the corrosion of tinplate, studying in particularthe effect of a typical fruit acid (e.g., citric acid) in dilute solutionon (a) the steel base of tinplate, ( b ) tin, (c) the tin-iron couple,( d ) tinplate.The investigation has also included a study of theinfluence of pH, presence of oxygen, and the corrosion products onthe further corrosion of these materials; e.g., the influence of tinsalts on the corrosion of iron, and of iron salts on the corrosion oftin and iron in the presence and in the absence of air.The corrosion of tinplate in various dilute acids has been investi-gated by G. Gire,66 who has also emphasised the important r61e ofthe presence of oxygen.Atmospheric Corrosion.In the field of atmospheric corrosion the need of well-planned,comprehensive researches, extending over a period of many years,has been realised, and work is in progress in many parts of the world.Up to the present, insufficient time has elapsed to enable the finalresults to be anticipated. The earlier work of W.H. J. Vernonfor the Atmospheric Corrosion Research Committee of the BritishNon-Ferrous Metals Research Association has already been reportedupon.67A Joint Corrosion Committee of the Iron and Steel Institute andthe National Federation of Iron and Steel Manufacturers began in1928 a comprehensive series of field tests under well-defined con-ditions and over prolonged periods. A special feature of the workis that all the materials tested are of known origin and have usuallybeen manufactured in the presence of members of the Committee;full particulars have been recorded regarding their manufacture,casting, and rolling, and each specimen can be traced back to itsexact position in the ingot.The investigations cover the effects64 J. Iron and Steel Inst., 1932, 25, 159; B., 1932, 606.65 D.S.I.R., Food Investigation Bd. Special Report, No. 40, 1931 ; B., 1931,591 ; Report of the Director of Food Investigation, Section E, 1932 and 1933 ;Trans. Paraday SOC., 1933, 29, 395, 830; 1934,30, 1059.s 6 Rev. Trav. Ofice P&ches Maritimes, 1930, 3, 409; 1931, 4, 355; 1933, 6,305. 67 Ann. Reports, 1928, 25, 29HEDGES : THE C0R;ROSION OF METALS. 141of (1) surface condition, (2) the presence of rolling scale and of vari-ations in the type of scale, (3) the nature of the basis metal andmethod of preparation of the surface on the protection afforded bycoatings of paint, (4) copper content on the corrosion of mild steel,and also (5) comparisons of ingot iron and several types of wroughtiron and (6) tests on high-tensile steels.The tests are being carried out under widely different climaticconditions a t four main stations in Great Britain and ten subsidiarystations in Great Britain and abroad. Marine, moorland, highlyindustrial, and urban atmospheres are comprised, as well as testsin railway tunnels, etc., and under arctic and tropical conditions.Comparative tests under service conditions are being conducted indifferent types of atmosphere on railway sleepers of the same steelwith and without addition of copper. The specimens have beenweighed and will be removed periodically in batches in order toenable corrosion-time curves to be constructed.A Sub-Committee on Laboratory Corrosion Tests has also beenformed to develop laboratory tests to give a true index of servicebehaviour. An improved, automatic, spray test has been recom-mended. Further work has been done on corrosion testing byexamining the alteration of mechanical properties.When the final results of this comprehensive research programmeare available, it may confidently be expected that the knowledgeof certain aspects of atmospheric corrosion will be considerablyadvanced.Simultaneously, the Committees on Corrosion of Iron and Steeland on Corrosion of Non-Ferrous Metals and Alloys of the AmericanSociety for Testing Materials have continued and extended theirwork on atmospheric corrosion, which has been in progress formany years. Some of the more recent results have been set forthand discussed in a Symposium on the Outdoor Weathering of Metalsand Metallic Coatings.69 This discussion is of a practical natureand is intended to illustrate certain proper uses to which the testdata may be put by engineers.Csntinuing his work for the Corrosion of Metals Research Com-mittee of the Department of Scientific and Industrial Research,W. H. J. Vernon 70 has studied the corrosion of copper in certainsynthetic atmospheres in the laboratory, with special reference tothe influence of sulphur dioxide in air a t different relative humidities.He has described an air thermostat, suitable for use in work of thisIn the meantime two reports have been published.68Iron and Steel Inst., Special Report No. 1, 1931 ; Specid Report No. 6,1934; discussion, J . Iron and Steel Inst., 1934,129, 357.6s Amer. SOC. Testing Materials, 1934, Pre-print.70 Trans. Paraday Soc., 1931, 27, 255; B., 1931, 7631 42 INORGANIC CHEMISTRY.kind,71 and a method has been worked out 72 for the preparationof atmospheres of any desired relative humidity. The rale of themoisture in iron rust in determining the critical corrosion humidityis explained in colloid-chemical terms by W. S. Patterson andL. H e b b ~ . ~ ~ P. R. Kosting 74 has conducted accelerated weatheringtests on soldered and tinned-sheet copper in atmospheres rich insulphur dioxide and carbon dioxide.A study by W. H. J. Vernon and L. Whitby 75 of the greenpatina which forms on the surface of copper exposed to merenttypes of atmosphere, has shown- that, contrary to the former belief,the patina consists mainly of basic copper sulphate. In the courseof time its composition accords with that of the mineral brochantite,CuS04,3Cu( OH),. In seaside districts the patina may containcopper chloride, but the basic sulphate predominates when urbanand marine conditions coincide. The sulphate is obtained fromsulphurous and sulphuric acids brought into the atmosphere throughthe combustion of coal. There seems to be no doubt that thelongevity of copper exposed to the atmosphere is due to the pro-tective properties of the film of basic sulphate. Methods havebeen worked therefore, for the rapid production of an artificialpatina of this substance by anodic treatment of the copper in asuitable electrolyte. Other artificial methods have been describedby J. R. Freeman and P. H. Kirby.77L. Whitby 78 has shown that magnesium carbonate predominatesin the corrosion product of magnesium in indoor or outdooratmospheres. No indication of the formation of a protective filmwas observed. The rate of corrosion increases with the relativehumidity of the atmosphere.A reflectivity method for measuring the tarnishing of highly-polished metals has been described by L. Kenworthy and J. M.Waldram,79 and some results obtained by this method for tin andBritannia metal are given. E. S. H.E. S. HEDGES.R. WHYTLAW-GRAY.w. WARDLAW.7 1 Trans. Faraday Soc., 1931, 27, 241; A., 1931, 815.72 W. H. J. Vernon and L. Whitby, ibid., p. 1; A,, 1931, 816.73 Ibid., p. 278; B., 1931, 762.74 Bur. Stand. J . Res., 1932, 8, 365; B., 1932, 553.75 J . Inst. Metals, 1929, 42, 181; B., 1929, 855; ibid., 1930, 44, 389; B.,1930, 992; W. H. J. Vernon, ibid., 1933,52,93; B., 1933,633; J., 1934, 1853.76 Idem, J . Inst. Metals, 1932, 49, 153; B., 1932, 940.7 7 Metals and Alloys, 1932, 3, 190; B., 1932, 986; ibid., 1934, 5, 67.78 Trans. Farachy SOC., 1933, 29, 844; A., 1933, 1017.79 J . Inst. Metals, 1934, 55, 247

ISSN:0365-6217    

DOI:10.1039/AR9343100094

出版商:RSC    

年代:1934

数据来源: RSC

摘要:

ORGANIC CHEMISTRY.PART I .-ALIPHATIC DIVISION.h'tereochemistry .THE numbers of theoretically possible structural isomerides in seriesof aliphatic compounds, though seldom required for stereochemicalpurposes, are of some interest as giving perspective. The followingare from the calculations of H. R. Henze and C. M. Blair. for satur-ated aliphatic open-chain series :NO. of C Hydro- Disubstituted pareffine,atoms. carbons. Alcohols. Esters. C,H,,X,. C,,H,,XY.5 3 8 9 21 3110 75 507 599 2,261 3,95915 4,347 48,865 57,564 3 12,246 576,22120 366,319 5,622,109 6,589,734 46,972,357 88,594,746Efforts to calculate the valency angles of carbon, oxygen, andsulphur in various open-chain and cyclic compounds have beencontinued by a number of workers, who have usually proceededfrom determinations of dipole moment or from X-ray diagrams. Thevalency angle for oxygen in ethylene oxide is 2 115" & 7" ; in di-phenyl ether? 142" -+ 8"; in phenols, 137"; in anisoles, 150";in diphenylene dioxide,* 120" ; in water,3 134" ; in dimethyl ether,115" & 7" 2 or 1 4 7 O .3 That for sulphur, in diphenyl sulphideJ3 is118" & 8" ; in thianthren,2 which is non-planar, is < 120" ; in potass-ium trithionates the third S atom forms two linkings both withsulphur atoms, at 103". On the other hand, J. S. Allen and H.Hibbert give some values 6 for the oxygen valency angle in the simplerrings which are considerably lower than the tetrahedral angle, asmight be anticipated from the strain theory: in ethylene oxideand in propylene oxide, 70"; in trimethylene oxide, 94"; in tetra-hydrofuran, 108" ; in tetrahydropyran ( pentamethylene oxide),93".They regard the tetrahydropyran ring as puckered (diplanar)144 ORUANIC CHEMISTRY.-PART I.and strainless, whereas the tetrahydrofuran ring is planar andstrained, thus accounting for the fact that in the carbohydrates thepyranose ring is more stable than the furanose ; the greater stabilityoE the y- over the iS-lactones, however, presents an obstacle. Thevalency angle of carbon in diphenylmethane 3 is 115" 5", whichmay be close to the tetrahedral angle (109" 28'). W. G. Penneycalculates that in ethylene the carbon valency angles (to the pairsof H atoms) are about 130". Many of the estimates of valency anglesquoted above differ considerably from previous estimates, so it maybe concluded that the available methods are as yet not sufficientlyadvanced to solve the problems of the angles present in chains andheterocyclic rings.Several interesting deductions from X-ray work on the shape oforganic molecules have been published. In CHBr, the angle betweenthe C-Br linkingsis 115", in CH,Br, it is 125" (as is also the anglebetween the C-I linkings in CH212); in CMe,Br the distribution ofthe four groups about the central carbon atom is tetrahedral.8The structures of cis- and trans-C,H,Br,, C2HBr3, CH,:CHBr,C,Cl,, and C2HC1, are all planar,g with interatomic distances C-Cof 1.3 A., as against 1.55 8.for C-C(H3) in CMe3Br. Durene10consists of a regular plane hexagonal ring, with the four Me groupsin the plane of the ring but displaced slightly towards the unsub-stituted positions ; the distance C-C is 1.41 A.in the ring and 1.47 A.from chain to ring. Naphthalene l1 consists of two regular planehexagons, with C-C 1.41 8. Chrysene 1, is planar and consists ofregular hexagons, with C-C again 1.41 8. In o- and p-C6H,C1,vapours the molecules are planar or nearly ~ 0 . ~ 3 These results areall in harmony with those based on the classical methods. On theother hand, the molecules of s-triphenylbenzene are stated14 to beasymmetric.#eometricaZ 1somerides.-Several studies among simpler poly-methylene ring derivatives have been made, which continue earlierknowledge. Of cis- (m. p. 115-117") and trans- (m.p. 230-231")1 : 2-dimethylcyclopropane- 1 : 2-dicarboxylic acid,l5 the formergives a simple anhydride (m. p. 54-56') with acetyl chloride, andthe latter only a polymeric anhydride ; the dissociation constantsProc. Roy. SOC., 1934, [A], 144, 166 ; A . , 476.Idem, ibid., p. 566; A., 18.lo J. M. Robertson, Proc. Roy. Soc., 1933, [ A ] , 142, 659; A., 1934, 18.l1 Idem, ibid., p. 674; A., 18.la J. Iball, ibid., 1934, [ A ] , 146, 140; A., 1162.l3 W. C. Pierce, J . Chern. Physics, 1934, 2, 1 ; A., 244.l4 (Mrs.) K. Lonsdale, Nature, 1934, 133, 67; A., 134.l6 K. von Auwers and 0. Ungemach, Annulen, 1934,511, 152; A . , 889.* R. W. Dornte, J . Chem. Physics, 1933, 1, 630; A., 1934, 18DREW. 145of the acids have been determined. Isomerisation of the cis-acidwith hydrochloric acid leads to fission of the ring; but cis-cyclo-butane-1 : 2-dicarboxylic acid (m.p. 138-139") gives the tram-acid with that reagent at 190" ; the dissociation constants of these acidsalso are given.l6 trans-cycloHeptane-1: 2-diol has been resolved 17by crystallisation of the strychnine salt of its hydrogen sulphatefrom alcohol ; the liberated dihydroxy-compound had [a]54so - 44-25"in water. Two stereoisomeric forms of aa'-diphenyltetrahydro-y-pyrone (m. p. 131' and m. p. 76") have been prepared.ls Someinteresting derivatives of hydrindene have been examined 19 by D. H.Peacock and B. K. Menon ; p-phenyl-'a- l-hydroxyhydrindene-2-propionic acid was obtained as a tmns-compound (I), since it didnot readily form a lactone; but when it was treated with hydro-gen bromide in acetic acid it was presumably isomerised to the cis-compound, since a lactone (11) was then formed.If the acid (I)was esterified and the p-toluenesulphonyl derivative of this estertreated with ammonia, another lactone (111) was obtained, which0-qo 1YC" OH p-\ &I 0, cc./l,H2(1.) (11.1 (111.)[R = CH2Ph]could also be prepared by the action of alkali upon (11) ; inversion ofthe configuration of the asymmetric carbon of the side chain hadtherefore been effected. The lactone, like the acid, contains threestructurally different asymmetric carbon atoms and would thereforebe able to assume four racemic forms if the trans- as well as the cis-lactone bridge could be produced.The three forms of cis-cinnamic acid (melting at 68", 58", and 42',respectively), so often the subject of examination, are apparentlyidentical in solution, as shown 20 by their rates of addition of bromine,and are therefore polymorphs.syn- and anti-o-Chlorobenzophenoneoximes have identical dipolemoments, but in the m- and p-pairs of oximes the higher-meltingform has the lower dipole moment.21o$ / CHR*CO,H / H16 H.Bode, Ber., 1934, 67, [B], 332; A . , 406.1 7 M. Godchot and M. Mousseron, Compt. rend., 1934,198, 837; A., 522.18 R. Cornubert and P. Robinet, BUZZ. SOC. chim., 1934, [ v ] , 1, 90; A., 778.I@ J., 1934, 1296; A., 1217.20 H. V. W. Robinson and T. C. James, J., 1933, 1453; A., 1934, 71.21 G. S. Parsons and C. W. Porter, J.A h r . Chem. SOC., 1933, 55, 4745;A., 1934, 131146 ORGANIC CHEMISTRY.-PART I.Many-membered Ring Compounds.-L. Ruzicka and collaboratorshave obtained 22 further examples of polymethylene ring compoundsand their ketones up to C%, and have discussed the relationshipsamong the physical propiities. Theregarding density and melting point :No. of CHydrocarbon :atoms 20 21 22 23 24 26(a) - - 0.850 0.850 - 0.847( b ) - - 46" 49' 47" 43"Ketone :(a) - 0.894 - 0.890 - -(b) 59' 46" 32" 39" 36" 42"following are revised data28 29 30 32 340.846 0.851 0.854 0.856 0.85648" - 57" 59' 66"- 0.887 0.887 - 0-88550" - 56" - 64"(a) density at 20" ; ( b ) melting point.The figures for the melting points are difficult to interpret, but fromthe densities Ruziclra deduces (Chem.and Id., 1935, 54, 2) thatthe rings above C,, are composed of parallel double chains, thestraight portions of which are identical with the %-paraffins instructure. This is confirmed by some X-ray results. However, itis to be noted that the cyclic hydrocarbons and ketones are actuallydenser than the corresponding normal chain compounds. A numberof large ring compounds containing nitrogen have also beendes~ribed,~3 e.g., cyclo-dipentadecamethylenedi-imine,J, W. Hill and W. H. Carothers have described 24 a number ofmany-membered cyclic anhydrides and cyclic esters. The anhydridesobtained by heating the acids [CH2],(C02H)2, where n = 4 t o 12and 16, with acetic anhydride are stated to be linear polymerides( M = 3000--5000) in which the unit -O*CO*[CH,];CO- is repeated ;on being heated in a still, they give volatile cyclic monomeric ordimeric anhydrides, together with more complex anhydrides formingtough fibrous solids. The volatile anhydrides readily polymeriseto substances which are regarded as large-ring anhydrides, re-sembling the so-called linear anhydrides mentioned above.A very interesting case of a large-ring compound is provided bythe phthalocyanine 25 of R.P. Linstead and collaborators. This22 L. Ruzicka, M. Hiirbin, and M. Furter, Helv. Chim. Acta, 1934, 17, 18;2s L. Ruzicka, M. W. Goldberg, M. Hurbin, and H. A. Bockenoogen, ibid.,24 J . Amr. Chem. SOC., 1933, 55, 5023, 5031; A., 1934, 171.Z5 C. E. Dent, R. P. Linstead, and A. R.Lowe, J., 1934,1033; A., 1114.A,, 285.1933, 16, 1323; A., 1934, 82DREW. 147stable substance has for its essential structural feature a 16-memberedring of 8 carbon and 8 nitrogen atoms arranged alternately in theN Cform of four cyclised pentagonal units (IV), with six double bonds.Theoretical considerations, as well as some X-ray evidence, indicatethat this ring is flat. The copper derivative, in which the copperatom replaces the two hydrogen atoms of the imino-groups andpresumably co-ordinates with the two remaining inner nitrogenatoms, is quite exceptionally stable to heat and to the action ofsulphuric acid. There is thus presumptive evidence that largeplanar indented rings can exist without much internal strain. Ifthe copper atom also lies in the plane of the ring, its valency dis-tribution must presumably be planar, whereas hitherto a tetrahedralsymmetry has been accepted ; and similar difficulties arise regardingthe distribution of the valencies to the tervalent nitrogen atoms ofthe imino-groups.However, as the authors point out, there is apossibility of free rotation of one of the four rings of phthalocyanine,which would have the effect of displacing an imino-group from theplane of the large ring and might therefore admit a combinationwith non-planar copper.The analogy between the phthalocyanine ring system and that ofthe porphyrins [shown in (V)] is remarkable, and the implication isborne out by a corresponding stability in the copper derivatives.The phenomena suggest that no great difference of strain is intro-duced in such cyclic systems by a substitution of N< for C<.The possible occurrence of large planar indented rings had alreadybeen discussed 26 by the Reporter in connexion with the polymethyl-enes, the only case in which the values of the angles could be cal-culated with some confidence.It was shown that many large ringsare capable of representation in axially symmetrical planar patterns,the total strain in the large rings being equal to that of simplerprototypes (cyclopentane, etc.). The rings (IV) and (V), althoughunsaturated and not quite symmetrical, are similar in outline tosome of these patterns, and are particular cases of the generalscheme.*a H. D. K. Drew, J . Soc. Chern.Ind., 1933, 52, 538148 ORGANIC CHEMISTRY .-PART I.The preparation by G . Komppa and S. Beckrnann (Naturwiss.,CH2-+I~ CH, 1934,22, 171 ; A., 658) of norbornylan (annexedformula), the parent hydrocarbon of the cam-phor group, is of interest from the point of viewof the strain involved in bridged-ring substances CH,-CH-CH,where the presence of Sachse rings is probable; it melts a t 86-87'and is highly volatile.Optical Activity .-The problem of calculating optical rotatorypower, never yet solved, has been brilliantly attacked by S. F. Boys,27who deals with the simplest case, that of a central atom surroundedby four different groups a t the corners of an irregular tetrahedron.Taking the shape of the dissymmetric molecule as that determinedby the close packing of four spheres, corresponding with the fourdifferent groups, about the central atom, the author shows that themagnitude of the optical rotation, as well as its sense, is completelydetermined by the arrangement of the refractive centres in themolecule; and develops a relatively simple formula in whichthe specific rotation is given in terms of the refractive index of themedium in which the rotation is measured, the total refractivitiesof each attached group, the radii of the groups, the wave-length ofthe light used, and the molecular weight of the compound.Con-sidering the difficulty of determining the correct values for the radiiof the groups in the given environment, the optical rotatory powercalculated from the formula agrees remarkably well with that foundexperimentally for several of the simpler compounds of carbon :[ a ] ~ calculated.[ a ] ~ experimental.1 vH2 1(CH,)(C,H,)CH(OH) ............... 9.3" 13.9"(CH,)(C,H,)CH(NH,) ............... 7.4 7.44(CH,)(C,H,)CH(CH,*OH) ............ 4.0 5.90(CH,)(C,Hs)CH(CHz*NH2) ......... 3-6 6.86The calculation gives also the absolute configuration ; e.g., forl-amyl alcohol the configuration is as shown in (VI), where CH,*OHis represented as at the apex of a tetra-hedron whose base rests below on theplane of the paper. It is pointed outthat, if one group canbe changed whilst'cH3 ation, the sign of the optical rotationshould change when the effective radiusis increased above that of the next largest group. This agrees withexperience ; e.g., amyl alcohol and amylamine are of opposite rotatorysign to all compounds prepared by substituting another group (nothydrogen) for the OH group, since OH and NH, are the only radicalsCH,.OH.................................the compound retains the same codgur-'(VI.)17 Proc. Roy. SOC., 1934, [A], 144, 655, 6'76; A., 832DREW. 149which have smaller atomic volumes than the CH, group; all otherradicals cause the CH,X group to be larger than the adjacentCH2*CH, group.A formula connecting rotatory dispersion with the nature of thegroups is also given; and the temperature effect is shown to be dueonly to variations in the properties of the medium.These papers, if capable of withstanding expert criticism, wouldcontain the solution to many outstanding chemical problems,notably that of the Walden inversion, and would therefore form awelcome contribution to knowledge.In connexion with the above, it may be noted that, according toD.H. Brauns,2* the specific rotations of the l-halogeno-2-methyl-butanes (fluoro-, chloro-, homo-, and iodo-) are approximately inthe same ratio as the atomic diameters of the (neutral) halogenatoms.The following optical resolutions of interesting forms of substancesmay be grouped together :(1) The dZ-form of dilactyldiamide (VII) is spontaneously re-solved 29 by crystallisation from water above about 35".CH3*VH*CO,HCH,*CH*CO,H s CH,*QH*CO*NH,CH,*CH-CO*NH,9(2) dl- a-p-Carboxybenzenesulphonyl-a-p-tolylthiolethane (VIII) isresolved 3O by means of a half-equivalent of Z-menthylamine ; thed-acid has [a]546l + 130" in chloroform, but gives an inactive sulphoneon oxidation.(3) The resolution of dl-erythronic acid has been completed 31 bymeans of brucine and quinine; the lactones have [.ID & 73".(4) dZ-Histidine monohydrochloride is spontaneously resolved 32on rapid crystallisation, its behaviour recalling that of atropinesulphate (A., 1928,653).( 5 ) dZ-p-Thiodipropionic acid (IX) is resolved 33 by means ofquinine; the acids have [a]= about 9 200".(6) Z-Allantoin, having [alga - 92" 24' (in water), has been28 J .Amer. Chem. SOC., 1934, 56, 1421; A., 866.29 P. Vihles, Compt. rend., 1934, 198, 2102; A., 876.30 F. B. Kipping, J., 1933, 1506; A., 1934, 71.31 J.W. E. Glattfield and L. R. Forbrich, J . Amer. Chm. SOC., 1934, 56,33 R. Duschinsky, Chern. and Id., 1934, 10; A., 196.33 A. Fredga., Svensk Kem. Tidskr., 1934, 46, 10; A., 393.1209; A., 757150 ORGANIC CHEMISTRY.-PART I.obtained 34 from inactive allantoin by means of the allantoinasesfrom soya-bean and from skate liver, which preferentially hydrolysethe d-form ; I-allantoin racemises quickly in neutral or alkalinesolution ; the possibility of optically active tervalent nitrogenbeing ruled out, the classical molecule (X) must be present (comparethe remaining formuls which are symmetrical in the keto-form).HN-C(0H)-NHNH-CH-NH NH-C- NH >cO HN- H-NH +q >coNR2$0 ~o-NH>CO ToH'fi(oH)-NH(X. 1(7) The resolution of 2 : 6-dithiaspiroheptane 2 : 6-dioxideYOS<cH2>>c<cH">SOy which i s of the " allenic type," is claimed,35though the activities observed were small.(8) A claim has been made that o-toluidine-3 : 5-disulphonic acidis resolvable 36 by means of strychnine.It may be noted here thatthe existence of di-o-isomerides in benzene, due to supposed fixationof the Kekul6 double bonds (see A., 1927, 47), has recently beenchallenged .37J. Clark and J. Read have described 3 novel methods of preparingd (and 1) -borne01 by crystallising impure d-bornyl d-bornoxyacetate,and of resolving dl-menthol by esterifying it with I-menthylglycineand fractionating the resulting diastereoisomeric pair ; Z-menthyl-glycine appears to be a valuable addition to the available opticallyactive acids.The only convincing example ofan optically active compound of quinquevalent arsenic has hithertobeen the p-carboxyphenylmethylethylarsine sulphide of Mills andRaper ( J ., 1925,127,2479), but G. Kamai 39 now reports an apparentresolution of p-tolylbenzylethyl-n-propylarsonium iodide, of whichthe d-form, with [a]K + 9-86' in acetone, was obtained; i t rapidlybecame inactive. An observed angle of rotation of + 0-22" isrecorded. This substance differs, of course, from the sulphide inthat it is a true arsonium salt.Tervalent arsenic compounds have not hitherto been re-solved. C. F. H. Allen, F. B. Wells, and C. v. Wilsonm now34 R. Form, P. E. Thomas, and P. de Groeve, Compt. rend., 1934, 198,689, 1374; A., 534, 695.35 H.J. Backer and I(. J. Keuning, Rec. trav. chim,, 1934,53, 798; A., 901.36 A. Sementzov, Ukraine Chem. J . , 1933, 8, 193; A., 1934, 763.37 A. Contrtrdi and A. Dansi, Rend. R. 1st. Lombard0 Sci. Lett., 1933, [ii],3 8 J., 1934, 1773, 1776.3B Ber., 1933, 66, [B], 1779; A., 1934, 197.40 J . Amr. Chem. SOC., 1934,56, 233; A,, 312.CH CH2 2The asymmetric arsenic atom.66, 203; A., 1934, 177DREW. 151report the fractionation of the d-bromocamphorsulphonate of thebenzophenarsazine (XI); the values of the rotatory power of the0arsenic radicals, calculated from the values for the separated salta,were [x]i6" - 24.9" and + 25.6", respectively, in 95% alcohol. How-ever, the active chloroarsazines could not be obtained. The pos-sibility of active tervalent nitrogen being neglected, the results, sofar as they go, point to the tetrahedral symmetry of tervalentarsenic.(Miss) M.S. Lesslie and E. E. Turner 41 have obtained a much moredefinite resolution of a phenoxarsinecarboxylic acid (XII) by meansof strychnine, the liberated d- and Z-acids having [a]fSil 111.5"in alcohol. However, the authors incline to attribute the activity,not to asymmetry of tervalent arsenic, but to a folding of the moleculeabout the axis 0 . . . As, whereby it becomes diplanar and thereforedissymmetric.The same authors 42 recently obtained evidence of dissymmetryin the arsonium salt (XIII), although the angle of rotation observedhere was only 0.12" (1 = 5461). In this case they attributed thelack of symmetry to restriction of rotation of the phenyl groupsabout the common bond, in accordance with current ideas.OEt OEtPh,C*b---O-I!'*CPh3 13.(XIV.)0 111 0 Br AsMeJH. H. Hatt has described 43 the meso- and racemic forms of ethyltriphenylmethylpyrophosphonste (XIV), apparently the onlycase of isomerism due to two structurally similar asymmetricphosphorus atoms; both esters give the same acid on hydrolysisowing to resonance.Optically active diphenylbenzene derivatives. Where there are twocentres of restricted rotation the same effect is produced as if therewere two asymmetric centres in the molecule ; hence in structurallysymmetrical molecules we should expect to find meso- and racemicforms. This has been realisedu in the forms (XV) and (XVI),4 1 J., 1934, 1170; A., 1118.43 Ibid., p.776; A., 1933, 962.44 A. E. Knauf, P. R. Shildneck, and R. Adarns, J. Amer. Chem. SOC., 1934,ra J., 1933, 1588; A., 1934, 181.56, 2109152 ORGANIC CHEMISTRY .-PART I.the second only being resolvable, since the first has a centre of sym-metry. The active forms of (XVI) had [a]ge - 16.2" and + 13.4"Me Br Br OHmv.1 (XVI.)in ethyl acetate. Reversible oxidation to an active quinone ofopposite rotatory sign without any racemisation was found to bepossible.Metallic Complexes containing Organic Radicals.-( a) Resolutionof octahedral cadmium salts. The optical activation of triethylene-diaminocadmium chloride, [Cd en,]Cl,, of the sulphate, and of severalother corresponding salts has been effected by P.Neogi and G. K.Mukherjee,a by making use of the acidic property of nitrocamphor.Only one active form of each salt was produced, and the active saltsracemised rapidly even in the solid state. The active chloride had[a]goe + 113.7" in water. Similar optically active octahedral zinccomplexes have been prepared by the authors.In such cases as the above, where only one enantiomorph of areadily inactivated substance is producible by the use of a singleresolving agent, it would seem almost open to question whether anyinformation as to the normal symmetry of the substance is obtained,for the optical activation might be the result of a temporary dis-tortion of the substance by the resolving agent, normal symmetrybeing reassumed, after an interval, on removal of the latter ; theenantiomorph of the first resolving agent would produce an equaland opposite distortion.A comparison of the magnitude of theeffects of several different resolving agents might, however, give therequired information. In those members of the diphenyl serieswhich are readily inactivated, an effect of the kind suggested seemsactually to occur .46(b) Isomerism among derivatives of palladium and platinum.A. A. Griinberg and V. M. Schulman have described4' the firstmembers to be discovered of the p-series of palladodiammines,formerly confused with the pink series of pallado-salts of the pallado-tetrammines. As had already been predicted,48 these yellow sub-45 J . Indian Chem. SOC., 1934, 11, 225; A., 640.46 Compare W.Brydbwna, Rocz. Chem., 1934, 14, 304; A , , 1011; M. S .Lesslie and E. E. Turner, J., 1934, 347; A., 538; M. S . Kharasch, J. K.Senior, D. W. Stanger, and J. A. Chenicek, J. Amer. Chm. SOC., 1934, 56,1646; N. E. Searle and R. Adarns, ibid., p. 2112.47 Compt. rend. Acad. Sci., U.R.S.S., 1933, 218; A., 1934, 379.48 H. D. K. Drew, F. W. Pinkard, G. H. Preston, and W. Wardlaw, J.,1932, 1895; H. D. K. Drew and G. H. Wyatt, J., 1934,56; A., 284DREW. 153stances are relatively unstable, passing into the corresponding cc-isomerides. The p-isomerides described, which can be obtained onlyfrom the acetates of the amines, are Pd(NH,),Cl,, Pd(C,H,N),Cl,,and the corresponding bromides.The stereochemical relationships among the a- and p-series ofdisulphines and diammines of platinum and of palladium have nowbeen determined.The a-disulphines of platinum are transformsand correspond stereochemically and structurally with the wdi-ammines, and not with the p-diammines as was supposed by Werner.For details of this rather complicated subject the original payers 49must be consulted.The type of valency distribution present in palladous and platin-ous compounds in which the metal is associated with four groups oratoms has been the subject of much work. Recent iiivestigationshave shown, with little remaining doubt, that the arrangement isalways, or nearly always, planar. P. S. H. Head and the Reporterobtained 50 well-defined cis- and trans-forms of each of the followingplatotetrammines : [Pt am ae iblC1, and [Pt ibz]C12, where am =NH,, ae = NH,Et, and ib = NH2*CMe,*CH,*NH,.A. A. Grunbergand P. Ptizyn, and F. W. Pinkard, E. Sharratt, W. Wardlaw, andE. G. Cox, have reported 61 cis- and trans-isomerides of diglycine-platinum, Pt(NH,*CH,*CO,),, where the carboxyl is presumablynot ionised from platinum. G. T. Morgan and F. H. Burstall havepreparedS2red and black forms of the soluble triammine, [Pt trp Cl]Cl,where trp = 2 : 2’ : 2”-tripyridyl, either of which, if monomeric,must be of planar symmetry (XVII). B. N. Dickinson has like-wise shown 53 the planar structure of the palladotetrammine,(XVII. )Pd(NH,),Cl,,H,O, by means of X-rays, in agreement with theprevious work of E. G. Cox. F. P. Dwyer and D. P.Mellor haveisolated 56 two f orrns of palladium bis-antibenzylmethyldioxime,49 H. D. K. Drew and G. H. Wyatt, J., 1934,56; A., 284; H. Saenger andW. Wardlaw, ibid., p. 182; A., 397.60 Ibid., p. 221 ; A . , 397.51 J . pr. Chem., 1933, 136, 143; J., 1934, 1012; A., 994.52 J . , 1934, 1498.54 J . Amer. Chem. SOC., 1934, 56, 1551; A., 945.63 2. Krist., 1934, 88, 281; A., 1161154 ORGANIC CHEMISTRY .-PART I.one of which should be dissymmetric on the basis of a pyramidalvalency distribution ; no resolution was effected. Claims of theresolution of compounds of 4-covalent palladium, platinum, andnickel have been made by Rosenheim, Reihlen, and others, whoseresults still remain unreconciled. H. D. K. D.Long-chain Unsaturated Aliphatic acid^.C.R. Noller and R. A. Banneret 55 have synthesised oleic acidand elaidic acid from 9-chloroiionaldehyde prepared from hepta-decenyl chloride (from oleyl alcohol), using Shoemaker and Boord'smethod.56 The acid obtained consisted of 63% of elaidic acid and37% of oleic acid.57 This is considered to be the first completesynthesis of elaidic and oleic acids. Contributions to the constitu-tion of higher unsaturated acids are given by Y. Inoue and K.Sahashi 58 in their examination of clupanodonic acid, and to thepolymerisation of its methyl ester by K. kin^,^^ who has examinedthe products of ozonolysis of the intramolecular reaction product ofthe methyl and the butyl ester, giving CO,H*C,H,,*CO,Bu, whichorients the ester grouping with respect to one double linking.Theother products of ozonisation are explained by a new formula formethyl clupanodonate.J. S. Long, A. E. Rheineck, and G. L. Ball 6o have continued theirresearches on the drying of linseed oil, using trilinolenic glyceride.They find the oxygen absorbed corresponds to 2 0 for each doublelinkage with the formation of polar molecules. The second stageis the association of polar molecules to €orm gels. The ageing oflinseed oil or trilinolenic glyceride consists in the gradual transitionof polar liquid phase to a solid phase of substantially the sameultimate analysis. S. Goldschmidt and I<. Freudenberg 61 haveexamined the oxidation of linolenic acid and its methyl ester byoxygen in the presence of a cobalt catalyst. The formation ofperoxides is not accompanied by the development of acidic groups,and all the linolenic acid has disappeared when 2 molecules ofoxygen are absorbed. The peroxides are very stable and the per-oxide value remains constant for many days.Consideration of thesetwo papers shows the stress laid in the onc case on peroxides and,55 J . Amer. Chem. SOC., 1934, 58, 1563; A., 991.56 Ibid., 1931, 53, 1505; A., 1931, 709.5 7 H. N, Griffiths and T. P. Hilditch, J., 1932, 2315; A., 1932, 1111.6 8 Proc. Imp. Acad. Tokyo, 1932, 8, 371; A., 1933, 145.59 Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1933, 21, 63; 1034, 24, 218;60 Ind. Eng. Chem., 1933, 25, 1056; B., 1933, 1016.61 Ber., 1934, 67, [B], 1589; A., 1200.A., 1933, 807; 1934, 1202MOBELL. 155in tlhe other, on association of the keto-en01 modifications of thesame peroxide causing passage from the fluid t o the solid state.From the Reporter’s unpublished investigation on the oxidation ofa- and p-ekeostearic acids or their glycerides combined with maleicanhydride, the formation of both peroxides and keto-enol groupstakes place depending on the position of the double linkages in themolecule.The association is marked in the peroxide groups and isfavoured by solvents of low dielectric constants. The results are inconfirmation of those obtained from the oxidation of @-elaeostearicacid from fung The association of the oxidation products ofdrying oils is to be looked for at the remote double linkages, whichseem to be capable of yielding peroxides on oxidation.In investi-gations of the above character it is of importance to have reliablemethods for the estimation of the groups formed by the oxidation,e.g., peroxide, hydroxyl, keto, etc. Improvements in the estimationof hydroxyl values of acid substances have been made by E. S. West,G. Hoagland, and G. H. Curtis.63 The previous methods wereapplicable only to .esters.Spectroscopic study of the elsostearic acids from tung oil showsthat the absorption spectra of the a- and the p-form differ sufficientlyfor identification, so that the composition of a mixture can bedetermined. 64The absorption of oxygen by linseed oil in the presence of catalysts[K,W(CN),, K,Mo(CN),, and K,F’e(CN),] has been examined byB. F. Chow and S.E. Kamerling,66 who found that the rate of absorp-tion was in the decreasing order from the first-named, and gave anempirical equation relating the rate of oxygen absorption to theoxidation potential. In the case of oleic acid oxygen is necessaryfor the reduction of the ferricyanides in HPO,” buffer, 5-6 mole-cules of 0 being required for the reduction of 2 molecules of ferri-cyanide. Acetoxime was a marked inhibitor of the oxygenabsorption.N. A. Milas’s66 view is that in all autoxidations the atoms towhich the oxygen molecule is initially added make definite con-tributions of 2 electrons ; metastable peroxides of high instabilityand energy content are formed and may revert to ordinary peroxides62 R. S. Morrell and S. Marks, J. SOC. Chem.Id., 1931, 50, 271.; B., 1931,540.63 J . Biol. Chem., 1934, 104, 627; A., 510.64 A. Dingwall and J. C. Thompson, J . Amer. Chem. SOC., 1934, 56, 809;G 5 J . Biol. Chern., 1934,104, 69; A., 261; B. F. Chow, J . Amer. Chem. SOC.,66 J . Physical Chem., 1929, 33, 1204; 1934, 38, 411; A., 1929, 1019;A., 631.1934, 56, 894; A., 607.1934, 607156 ORGANIC CHEMISTRY.-PART I.by transferring their excess energy to other molecules, or mayinitiate oxidation of other molecules. 67 The observed separationof peroxide from a benzene solution of a drying oil is assisted byprevious passage of the oxygen through the glyceride solution andindicates activation of gas in the solution.The " bloom " of a number of paint and varnish films has beencorrelated with their contact angles with water.68 Films withcontact angles below 65" show the defect of " bloom "; between65" and 90" the films do not condense water.Examination of themaleic anhydride compounds 69 of a- and p-elzostearin by the abovemethod has shown that the P-films are active and the a-compoundsare n0t.70 This attractive power is considered to be dependent onthe surface concentration of the active peroxides and their increasedassociation diminishes the attraction. A. H. Hughes 71 has shownthat the surface potentials of unimolecular films of a- and p-elso-stearic acid-maleic anhydride compounds are markedly different andthe unsaturated linkage of the p-compound increases the surfacepotential. The position of the oxidisable double linkage is important,because it is known that the p-compound is more easily oxidised andassociated, whereas the or-compound oxidises with difficulty and doesnot give an active peroxide.A.H. Hughes 72 has also examined the unimolecular films oflong-chain aliphatic compounds on aqueous solutions by surface-pressure and surface-potential methods in the series oleic, petro-selic, and Aa-isooleic acids, and has found that the dipole systemof the double linking has a marked effect on the adhesion to the watersurface and that proximity to a carboxyl group increases the dipolemcjment. The dipole moment of chaulmoogric acid containing afive-membered ring is greater than that of a double linking in astraight chain; a triple linking has a dipole moment greater thanthat of a double linking and causes greater adhesion to the surface.A.H. Hughes and E. K. Rideal 73 have determined the rate ofoxidation of the above acids, as well as of or- and p-elz?ostearic acids,by measurement of the change of surface potential with time. Thereaction velocity decreases with the compression of the film anddepends on the accessibility of the double linking to the oxidising67 Compare H. N. Stephens, J . Physical Chern., 1933, 37, 209; 1934, 38,g8 N. K. Adam and R. S. Morroll, J. Xoc. Chern. Ind., 1934, 53, 2 5 5 ~ ;68 R. S. Morrell, S. Marks, and H. Samuels, ibid., 1933, 52, 1 3 0 ~ ; B., 1933,70 N. K. Adam and R. S. Morrell, ibid., 1934, 53, 255q 2601'; B., 931.71 J., 1933, 338; A., 1933, 565.73 PPOC. Roy.SOC., 1933, [ A ] , 140, 253; -4., 1933, 679.419; A., 1933, 61 ; 1934, 607.B., 931.556.72 L O C . citMORRELL. 157agent and is also affected by the position of the double linking inrelation to the polar carboxyl group.The structural investigation of these long-chain unsaturatedaliphatic esters and acids, combined with observations on theirsurface properties as instanced by the work of Hughes and Rideal,will throw much light on many of the difficult problems of the acidsand esters which are met with in industry.Polymerisation of Long-chain Aliphatic Compounds.In paints and varnishes the consideration of micellar colloids isfavoured by some workers in contrast with the molecular colloidaspect advocated by Staudinger. A survey on these lines putsforward paint and varnish systems as containing micelles of mole-cules held together by primary valencies or adhesional forcesaccording to chance contact, the temperature of the system exertingconsiderable influence ; e.g., at 180' glycerol and phthalic anhydridegive a soft gelling resin mainly of straight-chain growth, but a t260" the product is brittle because cross linking (primary valencies)of the pre-formed molecular chains becomes more frequent in con-sequence of the activity of the p-C atom in the glycerol molecule.The sudden increase in the rate of gelation of tung oil at 270" and thebrittleness of the product are similarly explained.74 In a latercommunication 75 the ideas are developed to include the influence offree fatty acids, resins, driers, and pigments as dispersing or coagu-lating agents. The peculiar characteristics of tung oil films arestated to be due to random coagulation of large flocculates or to apartial orientation." Blooming " is ascribed to swelling of floccu-lants by absorption of water.H. Freundlich 76 considers resins as gels of highly polymerisedsubstaiices, the disperse phase consisting of a more highlypolymerised form of the material composing the continuous phase,and the plastic behaviour is parallel to that of glasses and is deter-mined mainly by the viscosity of the continuous phase, the dispersephase being of secondary importance; i.e., they are two-phasecolloids. For the development of plasticity with its variablecoefficient of viscosity and possibly yield value, some affinitybetween solid and liquid is essential.The phenomenon of thixo-tropy frequently met with in plastic masses and associated withloose packing of the particles demands attractive forces between thelatter of the van der Waals order. The above may be taken as the74 W. E. Wornam, J . Oil and (701. Chem. ASSOC., 1933, 16, 231; B.,76 Idem, ibid., 1934, 17, 119; B., 610.76 J. Soc. Chem. Ind., 1934, 53, 21th.1933, 79158 ORGANIC CHEMISTRY .-PART I.purely colloidal aspect , which correlates many phenomena success-fully, especially those of comparatively simple structure, but struc-ture is of great importance (cf. the properties and structure ofbentonite and kaolinite) and it is of equal importance in considerationof properties of oil films and resins.The neglect of investigationinto the structure and molecular arrangement of long-chain unsatu-rated oils and acids has introduced uncertainty concerning behaviouron oxidation and polymerisation. There is need for co-ordinationof the two aspects, because adequate knowledge of each is essential.The polymeric molecules may assume a linear form of repeatedunits, or a branch form which will lead ultimately to the building upof a, solid three-dimensional molecular structure (cross-linked poly-merisation). I n condensation polymerisation a third substance iseliminated (usually water) as a result of chain f0rmation.~7 Theapposition of chain polymerised molecules to form fibres may beproduced by flow and shear, whereby a thread of glassy polyesteris instantaneously converted by strain into an oriented fibre (J.W.Hill and W. H. car other^).^^ These linear o-polyesters have beenobtained from dibasic acids and glycols heated in a molecularstill to give tough opaque solids. The cross-linked form of poly-mpride is more difficult to investigate, the simplest representationbeing silicic acid. In long-chain unsaturated acids glycerideassociation of double linkages may proceed to a four-ring dimeride,for which there is yet no conclusive evidence. E. Rossman 79concludes that below 300" elaeostearic acid does not pass beyonda dimeride and has isolated a cydomonoelaeostearic acidand cydodielaeostearic acid. 1 CH/\vQH GH R = [CH2],*C02HMHC CH M = CH,*[CH,],CHRThe isomerism of elzostearic acid into the cyclic form is stated tobe irreversible.I n strongly heated tung oils further cyclopoly-merides are formed which cannot be depolymerised by heat (Ross-man). The production of dibasic acid with the loss of one doublelinkage has been suggested by L. A. Jordan *O as occurring in thefirst stage of the polymerisation. Further investigation is advisable,because the results of Rossman and Jordan are not in generalagreement with the behaviour of maleic anhydride compounds77 W. H. Carothers and collaborators, J . Amer. Chem. Soc., 1929, 51, 2548,2560; 1930, 52, 314, 711, 3292; A., 1929, 1165; 1930, 319, 452, 1272.78 Ibid., 1933, 55, 5023; A., 1934, 171.79 Fettchem. Umschau, 1933, 40, 96, 117; A., 1933, 807.80 J .Oil and Col. Chem. Assoc., 1934,17, 47; B., 333.MORZtELL. 159from a- and p-elzeostearic acid. W. Chalmers,sl in a discussion onmacropolymerisation reactions, criticises a stepwise reactionmechanism and supports a polymerisation chain mechanisminvolving (1) primary activation of the monomeride and (2) asubsequent process of concatenation which is rendered possible bythe presence of free terminal bonds on all intermediate stages. Thelinking of the monomeric units proceeds initially at a rate almostinstantaneous compared with that of activation, but for very greatchain lengths the rate becomes increasingly slow. There is experi-mental evidence in support of the above, but further work isnecessary to decide on the relative activities of the unsaturateddouble linkages, because the adoption of the dimeride view has asyet inadequate confbmation.I n the polymerisation of glycerides by heat it has been suggestedthat an interchange of ester groupings takes place slowly until thetemperature reaches 260".The mixed unsaturated glycerides mayyH,*OX p , * O X l yH,*OX 1 QH,*OXQH*OY QH-OY, YH-OY QH-OYCH,*OZ ' CH,*OZ, CH,*OZ CH,*OZ,(where X, Y , Z, X,, Y,, Z, are different fatty radicals inthe glycerides)associate at different rates, and a t higher temperatures and shortertimes of heating the iodine value may even be higher than afterlonger times of heating at lower temperatures. The ester inter-change between tristearin and tripalmitin has been criticised byT.Malkin 82 and J. C. Smith,83 who have shown that palmitic andstearic ethyl or glyceryl esters are dimorphous. From X-rayexamination, Malkin concludes that the triglycerides from tridecointo tristearin exist in three forms; the stable p-form with the highm. p. has long C chains tilted across planes formed by terminalmethyl groups, whereas in the a-form they are perpendicular to theseplanes. He favours a T formula for glycerides rather than an Earrangement. This interchange of esters, which seems unlikelyfrom Malkin's work, can only be very partial in the heat polymeris-ation of linseed oil and would not explain the separation of stearicand palmitic acids and a modification of oleic acid from the acetone-insoluble portion of the8 1 J .Amer. Chern. SOC., 1934, 56, 912; A . , 607.82 Trans. Faraday SOC., 1933, 29, 977; A., 1933, 1107; J., 1931, 2796;83 J., 1931, 802; A., 1931, 684.84 R. S. Morrell, J . SOC. Chern. Ind., 1915, 34, 1 0 7 ~ .A., 1932, 327; J., 1934, 671.160 ORGANIC CHEMISTRY.-PART I.Condensation Polymerisation.W. H. Carothers and F. 3. van Natta 85 have prepared fromL-hydroxydecoic acid a series of polyesters (M 2780--25,200) of thetype OH*( [CH,]s*CO*O),*[CH,]9*C02H. Strong oriented fibres areobtained only from esters of molecular weight greater than 9330.86J. W. Hill and W. H. Carothers 86 have produced from the acids[CH,],(CO,H), (n = 4-12 and 16), by heating with acetic anhydride,linear polymerides of a-anhydrides (M 3000-5000) of the type~O*CO*[CH,],,*CO*O*CO*[CH2]n*CO*O*CO*[CH2]n*CO*.In the mole-cular still, volatile p-anhydrides (fluid cyclic monomerides or crystal-line dimeric anhydrides) and more complex w -anhydrides areproduced, which are tough opaque solids capable of being drawn intopliable highly oriented films ; these, when heated long enough in themolecular still, are converted into p-anhydrides. When linearpolyesters of unit length greater than 7 are heated at 200-250"under conditions of molecular distillation, the chains couple to formlonger chains. The polyesters (M 10,000) can be drawn into toughpliable forms. It was recognised that depolymerisation by esterinterchange might occur in the molecular still as in the case of six-membered cyclic esters.87Polymeric methylene carbonates prepared from (CH,),( OH),(n = 5, 7-9, 11-14, and 18), butyl carbonate, and a little sodiumat 170" are depolymerised by heating with catalysts 88 in a vacuumand under certain conditions smooth depolymerisation to thecorresponding monomerides or dirneric esters occurs : the methodmakes it possible to obtain for the first time monocyclic esters ingood yields.The macrocyclic esters and anhydrides of the twopreceding papers have odours of musk-like character resemblingthose of ketones and lactones of the same ring size. The rings inthe neighbourhood of 15 atoms all have musk-like o d o u r ~ . ~ ~ Theformation of large ring ketones is considered to involve the inter-mediate production of a linear polyketone, which then decomposes ;the changes are similar to those for esters and anhydrides (above).Rings of more than 5 atoms are not regarded as strainless and theprobable nature of the strain in large rings is discus~ed.~0 Bifunc-tional esterifications generally yield cyclic monomerides or linearpolyesters depending on the reactant (most important), the nature ofthe unit, and the experimental conditions, especially dilution.It85 J . Amer. Chem. SOC., 1933, 55, 4714; A., 1934, 56.86 Ibid., pp. 5023, 5031, 5039, 5043; A., 1934, 171.87 W. H. Carothers, G. L. Dorough, and F. J. van Natta, &id., 1932, 54,88 J. W. Hill and W. H. Carothers, Zoc. cit.J. W. Hill and W. H. Carothers, Zoc. cit.7G1; A., 1932, 366.88 LOC. cit., see ref. 88MORREU. 161is well known that substituents (e.g., methyl) favour ring closure.The simplest possible structural situation for self-esterification isfound in the a-hydroxy-acids, which have been investigated for thefirst time; E-hexolactone has been prepared and its behaviourcompared with that of other cyclic or polye~ters.~~ E.0. Craemerand W. D. Lansing 92 have subjected polymeric w-hydroxydecoicacid ( M 25,220) in s-tetrabromoetliane solution to ultra-centrifugalanalysis. The molecular weight deduced from the specific sediment-ation is much too low and the value calculated from the diffusioncoefficient is much too high. The value calculated from the sedi-mentation equilibrium agrees fairly well with the above. Theauthors state their views as to limitation of ultra-centrifugalanalysis.In most instances, only small yields of cyclic ketones containingmany carbon atoms are obtainable by Ruzicka’s method, owing tothe tendency of the reactants to polymerise.A new method hasbeen developed 93 which to some extent overcomes these dificulties.For example, when a normal aliphatic dinitrile and an alkali-metalderivative of a secondary amine are allowed to react in highdilution, a cyano-ketimine is produced in good yield, from whichthe cyclic ketone is readily obtained by acid hydrolysis :M. Wadano, C. Trogus, and K. H e ~ s , ~ ~ put forward the view thatthe oxygen linkages in polymeric CH20 are of the same characteras in esters, amides, and semi-acetals and the mechanism of thepolymerisation and depolymerisation in water is similar to that ofthe rupture and formation of such linkings.I. Sakuradag5 statesthat there is a fundamental difference between viscosity propertiesof natural and synthetic polymerides and Staudinger’s viscosity ruleis not applicable to substances such as cellulose, starch, and caout-chouc. He has determined the viscosity of a number of syntheticand natural polymerides according to his own special formula.Another critic of Staudinger’s viscosity rule is A. J. Wildschut.96The application of Staudinger’s viscometric method is not validfor natural rubber, but holds for synthetic and plasticised natural91 F. J. van Natta, J. W. Hill, and W. H. Carothers, J . Amer. C‘hem. SOC.,1934, 56, 455; A., 392.g2 Ibid., 1933, 55, 4319; A., 1933, 1276.93 K.Ziegler et al., Annakn, 1933, 504, 94; A., 1933, 951; Ber., 1933, 66,94 Ber., 1934, 67, [B], 174; A., 493.95 Ibid., p. 1045; A., 870.96 Rec. trav. chim., 1933, 52, 935; .A., 1933, 1300.[B], 1867; A., 1934, 195; Annakn, 1934,511, 1 ; A., 894.REP.-VOL. XXXI. I162 ORGANIC CHEMISTRY .-FART I.rubber.strongly $he validity of the viscometric method.H. Staudingerg7 has replied to his critics and defendsPolymerisation of Unsaturated Aliphatic Hydrocarbons.The polymerisation of acetylene has been studied by G. Mignonacand E. D i t ~ , ~ ~ who have found that at 75" the products are benzeneand a fluid polymeride, C,H, (b. p. 7"), which on fractionation givesa yellowish-green polymeride (chlorene). F. Toul 99 discusses thecatalysis of acetylene polymerisation in mercury vapour light.W.Kemula and S. Mrazek,l from absorption spectrum measure-ments, have shown that benzene, C4H4, and derivatives of C,,H,are formed during the polymerisation of acetylene. The preparationof vinylacetylene, CH,:C€€*CiCH, from as-butylene dibromide byWillstatter and Wirth's method is communicated by E. A. Shilev,A. N. Makashina, A. E. Smirnova, and G. I. Yakimov.2 Thepolymerisation of vinylacetylene at 105' in steel bombs giveshydrocarbons, ClzHz2, c1&8, and C2,H,,, which are considered tobe cyclobutane derivatives. In the presence of acids a t 105"vinylacetylene yields styrene but not polystyrene.3 The mercuryderivatives of vinylacetylene and also the cc-halogeno- p-vinyl-acetylene are described by W. H.Carothers, R. A. Jacobson, andG. Ber~het.~ R. A. Jacobson, H. B. Dykstra, and W. H. Carothershave found that vinylacetylene and alcohols in the presence ofsodium alkoxide (NaOR) give C(CH,)IC*CH,.OR and describe themethyl, benzyl, and other etherse5 M. E. Cupery and W. H.Carothers have investigated the polymerides of divinylacetylene.When divinylacetylene is heated for several hours at its boilingpoint (85"), out of contact with the air, it is polymerised to a viscousoil (synthetic drying oil) ; about 8% is polymerised in 3 hours at 80"to give a dimeride (M 230), which is trans-1 : 2-divinylethynylcyclo-butane. A trimeride, bisvinylethynylcyclobutylacetylene, is alsoa polymerisation product. N. D. Zelinski, Y.L. Donisenko, N. S.Evantova, and S. I. Khromov have examined the polymerisationof butadiene, isoprene, dimethylbutadiene, and cyclohexadiene incontact with aluminium chloride. W. E. Vaughan has shown that@' Ber., 1934, 67, [B], 92, 1159, 1164; A . , 283, 879.g8 Compt. rend., 1934, 199, 367; A., 990.99 CoZZ. Czech. Chem. Comm., 1934, 6, 162 ; A., 852.2. physikal. Chem., 1933, [B], 23, 358; A., 1934, 168.Sintet. Kauchuk, 1933, No. 1, 4; A., 1934, 55.H. B. Dykstra, J . Amer. Chem. SOC., 1934, 56, 1625; A,, 990.Ibid., 1933, 55, 4665; A., 1934, 65.ti Ibid., 1934, 56, 1169; A., 751.7 Sintet. Kauclauk, 1933, No. 4, 11; A., 1934, 1089.a J . Amer. Chem. SOC., 1933, 55, 4109: A., 1933, 1249.Ibid., p. 1167; A., 753HIRST AND PEAT. 163the polymerisation of isoprene, between 286" and 571", is a bimole-cular association reac'tion and one molecule of dimeride is obtainedfor every 530 collisions of activated molecules.W. J. Jones andH. G. Williams have examined the action of chlorine on isopreneand have obtained a 38% yield of a-chloro-P-methylbutadiene,purified through the sulphone compound. A higher- boilingdichloride, a8-dichloro-P-methyl-Afl-buteneY was also obtained in45% yield.H. I. Watermann and A. J. Tulleners have polymerised isobutenein heptane solution in the presence of aluminium chloride to givemixtures of olefinic and cyclic products (M 132480).10 S. F.Lebedev and I. A. Livschitz l1 have examined the depolymerisationof triisobutene, (C4H& in the presence of floridin (active silicate)and have obtained a dimeride and a monomeride.The polymerisation of unsaturated hydrocarbons by alkali metalsand alkali metal alkyls has been investigated by K.Ziegler and hiscollaborators.12 Lithium is soluble in ethereal solutions of buta-diene (I), AaY-pentadiene (11), and py-dimethylbutadiene (111) andisoprene to give with (I) a resin of high molecular weight, with (11)pentene and H(C,H,),H (n = 2-5). An intermediate lithiumcompound is formed, CH,Li*C(CH,):C( CH,)*CH,Li, which reactsrapidly with a second molecule of (111). R. S. M.Carbohydrates.etc. etc.The aldehydo-galactose penta-acetate is easily separable from thegalactonitrile pente-acetate. A method is thus provided of syn-thesising the open-chain acetates of those disaccharides and ketoseswhose thioacetals are not available.The semicarbazones may beused in exactly the same way as the oximes.The Xeptanoses.-Miched and Suckfiill 38 prepared 6-iodo-d-galactose mercaptal 2 : 3 : 4 : 5-tetra-acetate from 6-iodo-diacetone-galactose by hydrolysis of the acetone groups, followed by treatmentwith ethyl mercaptan and acetylation of the product. This thio-acetal on hydrolysis by Wolfrom's method with mercuric chlorideand cadmium carbonate in the cold yields the open-chain 6-iodo-tetra-acetyl aldehydo-galactose (IV), If , however, during thetreatment with mercuric chloride the temperature is allowed to riseto 40°, a further reaction takes place, involving the removal of theiodine and the formation of the open-chain hydrate (V).Non-rever-sible ring closure occurs in pyridine solution, yielding the seven-mem-bered cyclic sugar, 2 : 3 : 4 : 5-tetra-acetyl d-galactoseptanose (VI).L. M. Mohunta and J. N. Riiy13 have effected the synthesis ofcorydaldine. The azide (XXIII) in boiling toluene solution wasconverted into the carbimide (XXIV), which gave corydaldine(XXV) when treated with phosphoryl chloride :CON, MeO(XXIII.) (XXIV.)An interesting communication has been published on the stereo-isomerides of narcotine and hydrastine.14 When Z-ct-narcotineis heated with methyl-alcoholic potassium hydroxide, racemisation(presumably a t the phthalide carbon atom) occurs, and from theequilibrium mixture formed, Z- p-narcotine has been isolated.Similarlly, from natural Z-hydrastine (regarded as Z- P-hydrastine),Z-ct-hydrastine has been obtained.Phenanthridine Alkaloid.-Tazettine, isolated by E.Spath andL. Kahovec,15 from Narcissus Taxetta, L., may be identical (i) withsekisanine, which accompanies lycorine in Lycoris radiata,l6 and13 J., 1934, 1263; A., 1111.14 (Miss) M. A. Marshall, F. L. Pyman, and R. Robinson, ibid., p. 1315;l5 Ber., 1934, 67, [B], 1501; A., 1237.l6 K. Morishima, Arch. exp. Path. Phurn~., 1897, 40, 221; A , , 1899, i, 92.A., 1236TURNER. 277(ii) with “Base VIII” of H. Kondo, K. Tomimura,, and S.1shiwatari.l’ Tazettine is oxidised to hydrastic acid, and affordsphenanthridine when distilled with zinc dust. Tazettine methiodidewas converted into a methine base, which spontaneously lost methylalcohol, and gave a methiodide, Hofmann degradation of whichgave 6-phenylpiperonyl alcohol (I), identical with the end productof the following synthesis :From these results the partial formula of tazettine (11) is deduced.Aporphine AZkaZoids.--The constitution (111) of laurotetaninefrom Litsea citrata, BI., was established by G.Barger, J. Eisenbrand,1,. Eisenbrand, and E. Schlittler,18 and shortly afterwards byE. Spath and K. Tharrer.lg The former workers synthesised twocompounds (IV) and (V) by the following process : vanillin ethylether (for IV) or isovanillin ethyl ether (for V), R*CHO, was convertedNHEtOll I(V. )‘ t G e(111.) P . 1into the azlactone, thence into the pyruvic acid, R*CH,*CO-CO,H,and the acetic acid, R*CH,*CO,H.Nitration of these two acidswas followed by preparation of the homoveratroylamides, whichwere then converted into (IV) and (V). Hofmann degradation of(V) led to 3 : 5 : 6-trimethoxy-2-ethoxy-8-vinylphenanthrene,l7 J . Phamn. SOC. Japan, 1932, 52, 51.l8 Ber., 1933, 66, [B], 450; A., 1933, 405.Ibid., p. 583; A,, 1933, 518278 ORGANIC CHEMISTRY .-PART 111.idemtical with the product obtained by a similar process fromON-diethyl-laurotetanine ; so the alka,loid must be (111). Spathand Tharrer converted laurotetanine into its ethyl ether, and theninto the methiodide of the latter. Decomposition of the metho-hydroxide gave a methine base, and this, in turn, gave a methiodide.The base from the latter gave trimethoxyethoxyvinylphenanthrene,and oxidation of this substance, followed by decarboxylation,produced trimethoxyethoxyphenanthrene (VI), identical with theproduct of decarboxylating synthetic 3 : 5 : 6-trimethoxy-2-ethoxy-phenanthrene- 10-carboxylic acid ; whence laurotetanine is (111).Similarly, E.Spath and K. Tharrer 2O have shown that boldine,from Boldea fragrans, Juss, is (VII).CH, OHOEt(VI.) (VII.) (VIII.)The alkaloid actinodaphnine was isolated by S. Krishna andT. P. Ghose 21 from Actimhphne Hookeri, Meissn (Nat. order,Lauraceae). In conjunction with E. Schlittler 22 the same authorshave elucidated its probable constitution. The data obtained areas follows : Actinodaphnine, which is oxidised to methylene-dioxyhemimellitic acid, forms an O-methyl ether, converted bymethyl iodide and sodium methoxide into a methiodide, which,with sodium hydroxide, affords a methine base.The last is methyl-ated (methyl iodide and silver oxide) to a dimethoxymethylene-dioxyvinylphenanthrene, from which the vinyl group is eliminatedby oxidation, followed by decarboxylation. m-Hemipinic acid isobtained by the oxidation of actinodaphnine, the O-methyl ether ofwhich, when treated first with methyl iodide and secondly withacetic anhydride, gives N-acetyl-0-methylactinodaphnine, togetherwith dicentrine. The latter alkaloid is formed by the N-methylationof actinodaphnine. N-Methyl-O-ethylactinodaphnine is convertedby sulphuric acid and phloroglucinol into a dihydroxy-compound,the dimethyl ether of which, when submitted to Hofmann degrad-20 Ber., 1933, 66, [ B ] , 904; A., 1933, 840.21 J . Indian Chem.SOC., 1932, 9, 429; A . , 1933, 168.22 Helv. Chim. Acta, 1934, 17, 919; A., 1236TURNEJZ. 279ation, gives the above trimethoxyethoxyvinylphenanthrene obtainedfrom laurotetanine.Strychnine.-M. Kotake and T. Mitsuwa 23 have proposed a newformula for strychnine, but R. Robinson24 has shown that it failsto account for much of the chemistry of the alkaloid. Amongrecent papers on strychnine and its allies should be mentioned fiveby R. Robinson and his collaborator^.^^ In the second of thesepapers is described the successful application of Hofmann degrad-ation to metho-derivatives of dihydrostrychnidine-A.Toad Poison.-H. Wieland, G.Hesse, and H. Mittasch 26 isolatedbufotenine from the skin of toads (Bufo vulgaris). Analyses of thepicrate and the methiodide suggested that bufotenine wasC14H1802N2. Degradation of bufotenine gave a base, bufotenidine,present in bufotenine extraction mother-liquors and identical witha base isolated by Mittasch from Chinese Senso. By analogy withhyaphorine (IX), bufotenine was regarded as (X), and bufotenidineas (XI). It has now been shown2' that the former method ofseparation of bufotenine as flavianate or picrate is unsatisfactory,- C*CH2*$JH*C06 b , f 3 & H 2 * C H ( NMe,)*CO,H\/CH NMe, + NMe (x.) 0 "(IX.) NHbut pure bufotenine oxalate is readily obtainable, and is found to beC12H160N2,H2C,0,,~20. The usual methods of attack on theconstitution (Hofmann and Emde degradation, oxidation, etc.)gave no positive results.Bufotenine methiodide is identical withbufotenidine hydriodide. Bufotenine and methyl iodide, inpresence of alcoholic thallium ethoxide, gave O-methylbufoteninemetho-salts, also obtained by methylating bufotenidine with methylsulphate and alkali. Bufotenine therefore contains (i) the indoleskeleton, (ii) a hydroxyl group attached thereto, and (iii) a dimethyl-23 Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1934, 24, 119; A., 908.24 J., 1934, 1490; A . , 1374.25 (the late) W. H. Perkin, R. Robinson, and J. C. Smith, J., 1934, 574;0. Achmatowicz and R. Robinson, ibid., 1). 581 ; L. H. Briggs and R. Robin-son, ibid., p. 590; (Miss) T. M. Reynolds and R.Robinson, ibid., p. 592;B. K. Blount and R. Robinson, ibid., p. 595; A., 788.26 Ber., 1931, $4, [B], 2099; A., 1931, 1310; Ann. Reprte, 1931, 28, 161.27 H. Wieland, W. Konsand, and H. Mittasch, Annalen, 1934, 513, 1 ; A.,1332280 ORUANIC CHEMISTRY .-PART III.amino-group attached to one of two carbon atoms not forming partof the indole structure.Biological considerations suggest a tryptophan structure, and,since the 2-position is free (positive Hopkins-Cole glyoxylic acidreaction), the hydroxyl group must be in position 4, 5 , 6, or 7.Positions 4 and 7 may be excluded, for no natural indole derivativesare hydroxylated in these positions, whereas 5- and 6-hydroxylationis common (eseroline ; harmine). The authors therefore synthesisedderivatives of both (5- and 6-) types.Methylation of the known6-methoxytryptamine with methyl iodide and thallium ethoxidegave a compound similar to the quaternary iodide obtained frombufotenine, but different from it. 5-Methoxyindole, treated firstwith methylmagnesium iodide and then with chloroacetonitrile,28gave (XII), which was reduced, the product being methylated withmethyl iodide in presence of thallium ethoxide. The compoundso obtained (XIII) was identical with O-methylbufotenine meth-iodide, from which it follows that bufotenine is (XIV) and bufo-tenidine is (XV).M e O b , - MeO&JH2*CN -NH NH (XII.)MeO&,CH,*CH2*NH, --> l!teObCH2*CH2*kMe3pNH NH (XIII.)HO(&,CH2*CH,*NMe2 6&,CH2*CH2*hMe3NH (XIV.) NH FV.)It is suggested that the statement of H.Jensen and K. K. Che11,2~that the bufotenines from different species of toads are not identical,is incorrect, since it is now shown that the flavianate method ofisolation leads to impure materials, vix., to mixtures of varyingproportions of bufotenine and bufotenidine with the base,C,,H1,0N2, obtained 3O by removing the elements of sulphuric acidfrom bufothionine.C. Schopf and W. Braun31 have isolated an “alkaloid,”samandarine, C19H,,02N, from the salamanders, salamundra macu.Zosaand s. atra. The “ samandatrine ” extracted by Netolitzky 32 from*e R. Majima and M. Kotake, Ber., 1922, 55, 3859; A., 1923, i, 156.z9 Ber., 1932, 65, [B], 1310; A., 1932, 1142.30 H. Wieland and F. Vocke, Annalen, 1930,481, 215; A., 1930, 1466.31 Annalen, 1934, 514, 69; A., 1935, 97.3a Arch.exp. Path. Phawn., 1904, 61, 118; A., 1904, i, 770TURNER. 2818. atra is shown to be identical with samandarine obtained either fromBelgian or Spanish salamanders. Each Spanish salamandercontains an average of 16.5 mg. of samandarine, the figures for theBelgian and Tyrolese species being 23-6 and 4.7 mg., respectively.Chemical investigation of samandarine has so far shown that it isprobably a derivative of ethylene oxide, and contains a secondarycarbinol group and an imino-group.Stereochemistry of Heterocyclic Compounds.0. Mumm and E. Herrendorfer 33 observed that, when quinolinewas treated with a mixture of cyanogen bromide and hydrogencyanide, a crystalline compound, C,H,N(CN),, was formed.Thiswith alcoholic ammonia gave a crystalline isomeride. Continuationof this work34 has given results of considerable interest and im-portance. Pairs of isomeric dicyanides were obtained with 3- and6-methyl-, and 6-methoxy-quinoline, and with @-naphthaquinoline.isoQuinoline gave only one dicyanide, and 8-methylquinoline anda-naphthaquinoline gave none under the conditions employed forthe preparation of the others. At higher temperatures these twocompounds, and also 2-methyl- and 2-phenyl-quinoline, reacted,but gave, instead of the dicyanide, the nitrile of the corresponding4-carboxylic acid, e.g., (I). The reaction of quinoline derivativeswith cyanogen bromide and hydrogen cyanide recalls the work ofCNR e i ~ s e r t , ~ ~ who found that quinoline, when treated with a mixtureof aqueous potassium cyanide and benzoyl chloride, was convertedinto the nitrile (11), which gave quinoline-2-carboxylic acid inpresence of mineral acids.Mumm and Ludwig regarded the twoCNCN(111.)33 Ber., 1914, 47, 758; A., 1914, i, 574.34 0. Muinm and H. Ludwig, AnnuZen, 1934, 514, 34; A., 1935, 92.35 Ber., 1905, 38, 1603; A., 1905, i, 472282 ORGANIC CHEMISTRY.-PART 111.quinoline " dicyanides " as cis-trans-isomerides (111) a.nd (IV) of atype not hitherto obtainable. Both isomerides with hydro-chloric acid a t 150" gave quinoline-2-carboxylic acid ; both, whentreated with iodine in chloroform solution, in presence of sodiumacetate, gave 2-cyanoquinoline ; and both were converted by iodine,in alcoholic pyridine solution, into the same apocyanine dye (V).s-Dioxaspiroheptane (VI) and its thio-analogue (VII) have beenprepared by H.J. Backer and K. J. Keuning.36 Some evidence hasbeen obtained that a disulphoxide of (VII) is capable of exhibitingoptical activity.A dipyrrylbenzene (VIII) has been obtained 37 in cis- and tram-forms, and the latter has been resolved. The active forms areresistant to racemising influences.\'/ CO,HW. Brydowna 38 has effected the partial resolution of the strych-nine and quinine salts of 2 : 3'-dipyridyl-2' : 3-dicarboxylic acid(IX), but the acid itself was not obtained optically active.The stereochemistry of such compounds is still in a very unsatis-factory condition, as virtually nothing is known of the moleculardimensions and configuration of such common ring compounds aspyrrole and pyridine.W.Leithe 39 resolved dl-l-benzylisoquinoline (X) with tartaricacid, and concluded that the specific rotation was & 9", in benzenesolution. Repetition 4O of the resolution with bromocamphor-36 R a t r a v . cT+im., 1934,53,812; -4., 900; ibid., 1933,52, 499; A . , 1933, 834.37 C. Chang and R. Adams, J . Amer. Chern. SOC., 1934, 56, 2089; A., 1369.38 Rocz. Chem., 1934, 14, 304; A , , 1011.*" Ber., 1934, 67, [ B ] , 1261; d., 908.3p Monatsh,., 1929, 53-54, 967; A., 1929, 1461TURNER. 283sulphonic acid gave the much higher rotation of - 72" for theZ-base. The latter, when converted into tetrahydroprotoberberine(XI) by the method of E.Spath, P. Berger, and W. Kuntara,4lgave a laevorotatory specimen of (XI) which, after crystallisation,was optically pure. This proves that the lavorotatory bases ofthe berberine class correspond to natural laudanosine (Z-rotatoryin carbon disulphide and d-rotatory in chloroform), which in turncorresponds to Z-a-phenylethylamine.A new chapter in stereochemistry has been opened in connexionwith the configuration of heterocyclic rings. As recorded in theseReports,42 E. Bergmann and M. Tschudnowsky 43 found thatthianthren had the considerable dipole moment of 1.68 D, a factonly to be explained on the assumption that the thianthren moleculeis folded. A redetermination of the dipole moment by G. M. Bennettand S. Glasstone 44 gave the value 1.6 D, and these authors pointedout that the valency bonds of sulphur in thianthren must thereforemake an angle of less than 120" with one another.The corre-sponding angle in thianthren disulphoxide (XII) is not known, butH. Baw, G. M. Bennett, and (Miss) P. Dearns 45 have made a carefulsearch for the third disulphoxide which should be capable of existenceif the folded configuration of thianthren persists in the dioxides.The same authors have extended the work of K. Fries and W. Vogt,46by examining the products of oxidising various thianthrens.Whilst, however, 2 : 6-dichlorothianthren was shown to give riseto a monoxide, a monosulphone, two dioxides, a trioxide, and adisulphone, a third dioxide could not be detected, although thesuccessful isolation of so many individuals clearly indicates thecare with which the investigation was prosecuted. Similar resultswere obtained with 2 : 6-dimethyl- and 2 : 6-dimethoxy-thianthren :two disulphoxides were obtainable, but not a third.A perhaps unexpected result was later obtained with diphenylenedioxide, the dipole moment of which was found to be zero.47 Itfollows that the molecule of diphenylene dioxide must be planar,with an angle of about 120" between the oxygen bonds.(Miss) M. S. Lesslie and E. E. Turner 48.point out fhat in a com-pound of the general formula (XIII), in which A and B are the sameelement, or are different, there is every reason to believe that thefour lines joining the centres of A and B to the centres of the carbon4 1 Ber., 1930, 63, [B], 134; A., 1930, 350.42 Ann. Reporte, 1932, 29, 185.43 Ber., 1932, 65, [B], 458; A., 1932, 507. 44 J., 1934, 128; A., 349.4 5 Ibid., p. 680; A., 781. Ber., 1911, 44, 756; A., 1911, i, 395.4 7 G. M. Bennett, D. P. Earp, and S. Glasstono, J., 1934, 1179; A., 1058.4 8 Ibid., p. 1170; A,, 1118284 ORGANIC CHEMISTRY .-PART 111.atoms to which A and B are attached, will pass through the centreof X or of Y. This condition can be fulfilled even if the planeXAB is inclined, about the axis AB, to the plane YAB, as it is int hiant hren.When A and B are not identical, it is still possible for XAB andYAB to be planes, and for these to be inclined to each other. Theauthors take the view that, when the atomic radii of A and B aremarkedly different, the stability of a folded structure will be greater.It is shown by calculation that, when A is an oxygen atom (radius,0.66 8.) and B is a tervalent arsenic atom (radius, 1-21 k), the mostprobable configuration of such a system is one in which theangle between the planes XAB and YAB is between 150" and 180".An attempt to test this view resulted in the optical resolution of10-methylphenoxarsine-2-carboxylic acid (XIV), the enantiomorphicforms of which possessed very high optical stability. This factmakes it very improbable that the observed activity is due t o(XII.) (XIII. ) (XIV.)the presence of an " asymmetric tervalent arsenic atom," but furtherwork should clear up this matter. In view of the results obtainedby 0. Mumm and H. the whole subject needs carefulconsideration.From another quarter,49 a claim has been made that tervalentarsenic can give rise to optical activity, but48 the evidence putforward requires considerable amplification.The discovery of molecular dissymmetry in the phenoxarsineseries makes it almost certain that a large number of analogousstructures will be resolved. It will be of interest to know whethersuch activity occurs in substances of natural origin. Possiblymolecular dissymmetry of the new type, like that due to restrictedrotation, is not made use of by nature.E. E. TURNER.4* C. F. H. Allen, F. B. Wells, and C. V. Wilson, J . Amer. Chem. Soc., 1934,56, 233; A., 312

ISSN:0365-6217    

DOI:10.1039/AR9343100143

出版商:RSC    

年代:1934

数据来源: RSC

摘要:

ANALYTICAL CHEMISTRY.1. GENERAL METHODS, ETC.IN this Report it has again been considered desirable to present shortmonographs on some branches of analytical chemistry, where muchwork has been carried out recently and the time seems fitting forthe presentation of a connected summary of the advances made.Achmption on Precipitates in Gravimetric Determinutions.--Inquantitative determinations depending upon the precipitation of adefinite compound, it is essential to know whether the precipitateis truly the desired compound. It is well known that adsorptioneffects, due to alkalis or to the difficulty of eliminating an anioncompletely (as in the case of the sulphate ion in precipitatingaluminium hydroxide), may introduce serious errors if not recognisedand dealt with.Precipitation of barium sulphate under variousconditions is, perhaps, the best known example of co-precipitationof cations to a greater or less extent according to the nature of thecation. The general question of contamination of crystalline solidsystems, whether obtained by precipitation from solutions, frommelts, or by condensation from vapours, forms the subject of animportant series of papers, now summarised conveniently.1 Inwhatever manner produced, the crystalline precipitate is formeddiscontinuously. The resulting crystal precipitates may thereforeconsist of " growth " conglomerates holding adsorbed impuritiesdeposited regularly, or may contain ions of the same kind as that ofthe lattice but as foreign molecules either adsorbed in certain layersor in solid solution.Impurities will be more serious when thecrystal has a mosaic or " amorphous " structure. Quantitatively,these effects will be manifested by the departure of the precipitatesfrom the strict stoicheiometric composition of the desired compound,arising, for example, from the inclusion of foreign barium salts(or sulphates of other metals) in barium sulphate, and of othersulphides (or salts) in those cases where a quantitative precipitationis made by way of a sulphide.While these views are probably sound in general, a particularstudy of adsorptive properties of barium sulphate precipitates whencroceine scarlet 3BX is employed for staining the crystals, showedthat the greatest adsorption occurred with irregular crystals.1 D.Balarew, 2. anal. Cliem,, 1934, 96, 81; A,, 267286 ANALYTICAL CHEMISTRY.Orthorhombic crystals take up little dye, and that is distributedlocally within the crystaL2 Adsorption is considered to take placeduring the brief periods which may occur when a change in themanner of crystal growth takes place. It is suggested that leastadsorption in the gravimetric precipitations of barium sulphatewill result if conditions are chosen so that the precipitate consists,as far as possible, of perfect orthorhombic crystals.It is interesting to consider how it is possible to arrive a t depar-tures from true stoicheiometric relations in a neutral salt depositedfrom an electrically neutral mother-liquor. A likely explanationis that some cations (or anions) of the crystal and a correspondingnumber of anions (or cations), e.g., those derived from the mother-liquor, are deformed in such a way as to form electrically neutralgroups externally, but not necessarily neutral atoms or radicals,in so far as the electronic arrangements of the atoms or groupsthemselves are concerned.It follows that care must be exercisedin the final treatment quantitatively of any precipitate to ensurethat the foreign substances are either expelled during an ignition orremoved so far as may be by suitable treatment of the precipitates.Fortunately, there are many cases in practice where the conditionsdescribed above do not introduce serious errors in ordinary cases,but the possibility of structural contamination of precipitatescannot be ignored in very accurate work.Radioactive Methods in Technical Problern~.~-An interestingreview of methods of investigating certain problems by the use ofradioactive processes has been made.X-Ray examination hasshown that active charcoal occurs in the form of microcrystallinegraphite, and it has been assumed that adsorption occurs at theprism faces or sides of the graphit’e crystals where free carbonvalencies may be expected to occur, and not on those faces of graphitecrystals which form the bases. A direct demonstration of this isobtained when a small graphite flake is immersed in an atmospherecontaining radon. On placing the flake on a photographic plate,marked blackening i s found due to a-particles arising from radonadsorbed in the prism surfaces bounding the edges of the flake, butvery little effect is observed where the base of the flake rests on theplate.The fact that small quantities of various admixtures in asubstance can often be adsorbed completely by impurities containedtherein (e.g., in slag inclusions of metals) may probably account forTammann’s observations that when alloys containing ordinary lead,to the extent of about 1 yo in tin, or 5% in bismuth, have thorium-BE. G. R. Ardagh, R. E. Richardson, L. A. Richardson, and L. M. Humber,J . SOC. Chem. Id., 1934, 53, 1035.1..H. Kiiding and N. Riehl, Angew. Chenz., 1934, 47, 263; A,, 617FOX. 287added to them by a process of melting, the radioactive material isfound almost exclusively a t the edges of the crystal grains and notuniformly distributed throughout the alloy.This has nothing todo with the radioactivity of the lead isotope, Th-B, for it was foundby H. Kiiding and N. Riehl that if lead charged with Th-B weremelted with tin, radioactive lead was distributed uniformly through-out the alloy. This method of examining alloys for crystal grainand slag inclusions agrees with the results obtained by etching themetal with various reagents.Von Hevesy and Paneth’s well-known method of radioactiveindicators, whereby a, radioactive isotope can be deposited with itsinactive isotopic element, is not confined to these elements. It isnecessary that the element under examination should be capable offorming an insoluble compound with some other element which hasa radioactive isotope.This points the way to the detection oftraces of elements which have no radioactive isotopes.X-Ray Methods in C’hemicul Analysis.-A critical study of themethods and of the variables peculiar to the apparatus was madewith a Siegbahn type of apparatus.4 Special attention was directedto the evaluation of the spectrograms. The method employed wasto hammer the sample of powder into the surface of a copper anti-cathode, and to ensure uniformity of emission of electrons from a flatplatinum spiral coated with barium oxide-strontium oxide powder,the filament being wound tightly and regularly, and carefully centredin the electron shield. By visual observation of the fluorescence,the evenness of the stream of electrons over the “ focal ” area of theanticathode was observed and adjusted.Rocking of the calcitediffracting crystal could also be applied to correct any slight irregu-larities in the distribution of electrons. When all precautions weretakcn for regulat’ing the voltage, time of exposure, development ofplates, and general mechanical procedure, values from the platescould be trusted to within 5%. It was shown that only thoseanalyses which were made under strictly comparable conditionscould have any claim to accuracy, and that an absolute method ofanalysis should then be possible. Lines arising from it single ele-ment would be utilised in each determination, by comparison with aset of lines of the element obtained on the same photographic platewith various proportions of the element in a mixture similar to thatunder test.The results are set out in a graph showing log (time ofexposure)-density, since this is a more suitable function for deter-mining the proportion of the element from a measurement of thedensity of the plate than that usually adopted in photography of thevisual spectrum, viz., log intensity-donsity . The method proposed4 E. Wainor, J . Amr. Chem. Soc., 1934, 56, 1653; A., 1084288 ANALYTICAL CHEMISTRY.is apparently more widely applicable than that of Laby, which is,in general, restricted to elements of near atomic numbers.The question of the sensitivity of the X-ray method of chemicalanalysis has been re-examined, and it is reported that for certainalloys, metals can be detected by cathode-ray excitation downto 1 part in 105, and in powders elements can be found to theextent of about 1 part in 2 x lo4, particularly if the shorterwave-lengths are empl~yed.~ It is clear from a perusal of recentwork on the application of X-ray methods of analysis that suchmethods will take their place side by side with spectrographicmethods, and, indeed, will replace them in many cases, sincethe X-ray spectrograms are so much simpler and easier tointerpret.Spectrographic Methods.-Although no striking new features arereported during the year, a few modifications of accepted practicemay be indicated.When a substance which is being excitedelectrically to the state of emission is simultaneously heated, thelength, width, and intensity of some of the spectral lines mayalter.By selecting a line of an element in a mineral under investig-ation, susceptible to such effects, and photographing it at fixedintervals on a plate which moves vertically at a fixed rate, thevariation in the length, breadth, and intensity of the line is ascer-tained. This forms the basis of a method for estimating theelement to which the line is due.6An adaptation of the visual flame spectrum enables a determin-ation of certain cations-alkali metals, alkali earths, and thallium-to be made with an accuracy of about & 10%. The concentrationof the solutions varied from 2 or 3% to 1 x lo4%, and even lessin some cases. The procedure is to atomise a few C.C.of the solutionin a Lundegbrdh flame atomiser burning acetylene. I n front ofthe slit of the spectroscope there is placed a rectangular cell of planeparallel glass sides, about 20 cm. long and 2 cm. wide, divideddiagonally by means of a plane parallel glass septum. One halfof the cell contains water and the other half a solution ofcopper sulphate or potassium permanganate to act as lightfilters. The critical strength of solution for various con-centrations of the element under examination a t which certainspectrum lines vanish is ascertained, and curves connecting thelogarithm of percentage concentration with thickness of layer offilter are drawn for each element. Since other cations may intro-duce errors, the solution under test must be compared with oneA.Frtessler, 2. Physik, 1934, 88, 342; A., 617; R. Glooker, Metallzuirt.,1933, 12, 599; A., 1934, 979.6 A. Bath, Compt. rend., 1934,198, 566; A., 380FOX. 289containing the disturbing element.' The method is clearly capableof extended application. In dealing with the sparking of solutions,the apparatus devised by F. Twyman and C. S. Hitchen has beenfound available for the spectroscopic determination of Nb, Be, Ti,V, W, Mo, Cry and Pb, when used with the logarithmic sector.Concentrations as low as 5 x lo4% of beryllium can be estimatedwith an error no greater than 5%.9In view of the importance of a knowledge of the content of fluorinein water supplies, it is interesting to note the rapid spectroscopicmethod now available lo either visually or photographically.Thisdepends on the observation of the head of the blue-green CaF bandat 15291. Where the water residue-about 12.5 mg. is taken-isessentially calcium and magnesium, the visual method is available.The residue is placed in the cavity of a cored graphite electrode,impregnated with calcium chloride, and an arc carrying about15 amps. is struck. This arc shows the 15291 fluoride band whichpersists for various times according to the proportion of fluoride inthe water residue, but it disappears when all the fluoride hasvolatilised. By plotting the percentage of fluorine in the residueagainst the number of seconds before disappearance of the band head,a curve can be drawn from standard mixtures, enabling the quantityof fluorine in the mineral residue from the water to be read off.When the water residue is mostly saline, the visual method failsand the spectrographic method is necessary.In this case, the arcis kept burning for one minute, this being sufficient to volatilise allthe fluorine likely to be found in waters generally. The intensity ofthe band head is compared with that of known standards in theusual way. Quantities of fluorine down to 0.05 part per million canbe estimated,Two other spectrophotometric determinations may be consideredhere. Aluminium may be detected by means of the lakes it formswith a number of dyestuffs, but the great majority of these are notsensitive enough to estimate 1 or 2y of metal. Eriochrome-cyaninR does, however, detect as little as 0 .5 ~ ~ and even l y can be foundwhen mixed with as much as 100 times the quantity of iron,chromium, or manganese. For quantitative work, advantage istaken of the fact the aluminium lake has its maximum absorptionabout 1,530 mp in the green part of the spectrum, whereas that of the7 A. I(. Russanov, 2. anal. Chem., 1934, 98, 335; A,, 1190; H. Lunde-8 Proc. Roy. Soc., 1931, [A], 133, 72; A., 1931, 1260.a W. R. Brode and J. G. Steed, Ind. Eiag. Chem. (Anal.), 1934, 6, 157; A,,gArdh, '' Die Quantitative Spektralanalyse der Element0 " (Jena, 1929).748.10 A. W. Petrey, ibid., p. 343; A., 1189.REP.-VOL. XXXI. 290 ANALYTICAL CHEMISTRY.original solution is in the violet-blue region. The position of theband maximum is affected by varying p=, and the aluminium solu-tion containing dye is therefore held at pH 6 by means of a buffermixture of acetic acid with sodium and ammonium acetates.Theextinction coefficient of the buffered solution of aluminium anddyestuff at A531 mp is measured, and this gives an estimate of thealuminium coEtent of the solution. As an example, 107 of the metalper 100 C.C. gives an extinction coefficient of about 0.2 in the con-ditions laid dom. l1 This procedure of monochromatic spectro-photometric determination is of fairly wide application bothvisually and photographically.In addition to the uses of diacetyl as a reagent, it has foundapplication for imparting aroma to butter in those cases where theminute proportion present in the butter naturally has been reducedback to acetylmethylcarbinol from which it is presumed to beformed in fresh butter.I n these circumstances, it becomes ofinterest to ascertain whether it is possible to detect addition, whenthis is more than might be found normally, i.e., about 0.0005%(the true maximum in fresh butter is really unknown). One testis to convert t'he diacetyl into dimethylglyoxime and determine itcolorimetrically by means of the nickel compound. An alternativemethod has been proposed l2 from the estimation of the extinctioncoefficients of the bands in the regions 4200 and 2870 8. Thediacetyl is distilled out of the butter by means of alcohol, and thedistillate is examined spectrophotometrically and compared withcurves drawn from known concentrations in 88% alcohol by volume.Now, reduction of the diacetyl may well proceed as far as &-butyleneglycol, and it is known that certain organisms bring aboutthe formation of acetjylmethylcarbinol.Further, during the oxid-ation of the alcohol, when butter becomes stale, small quantities ofthe butter itself are broken up during the steps leading to rancidity,and it is probable that volatile substances are formed which willdistil over with the diacetyl. What effect these would have on thedetermination of the extinction coefficient is unknown. Untilfurther information on these matters is available, it would appearpreferable to rely on the nickel test for diacetyl, rather than on thespectroscopic determination.Of the various uses for photoelectric colorimetry, the arrangementof B.Lange l3 has been applied to the direct examination of water11 F. Alten, H. Weiland, and E. Knippenberg, 2. anal. Chem., 1934, 96, 91 ;1% H. Rfohler and F. Almasy, ibid., p. 399; A., 635.l3 Chem. Pabr., 1933, 457; A., 1933, 44; E. Naumann and K. Naumann,2. anal. Chem., 1934,97, 81 ; A., 744.A., 271FOX. 291for iron, manganese, and phenol. The iron is determined from thedepth of colour of the thiocyanate, and the manganese from that ofpermanganate. Phenol is estimated by the blue colour given byFolin and Dennis’s reagent, phosphomolybdic acid. It is not clearwhy the authors have not, in this case, used one of the dyes producedby coupling the phenol with a diazonium compound.The type ofinstrument used is available for the nephelometric determinationof sulphates as barium sulphate and lead as lead sulphide, in bothcases with the aid of a stabilising colloid such as gum arabic.Of the numerous fluorescence reactions described, one may bespecially mentioned, vix., the orange-yellow fluorescence shown inultra-violet light by boric acid solutions to which cochineal extractis added.14 The solution must be brought between pE 5.8 and 6.9,and buffered with equimolecular mixtures of KH,P04 andNa2HP0,,2H,O. The test is four or five times as sensitive as thatgiven by turmeric. If necessary, carbonates should be removed,since they interfere with the fluorescence, but some other anions arewithout effect. Heavy metals in general prevent the formation ofthe specific fluorescence colours, and certain cations develop adifferently coloured fluorescence.We have no doubt it would bepossible to distil off the boric acid by means of methyl alcohol in thewell-known manner and so separate it from the cations, an advantageof some importance since it is claimed that the fluorescence withcochineal extract is specific for boric acid in the conditions described.Interferometric and Other Measurements of Refractivit y.-Opticalinterferometers have been used frequently to determine differencesin refractivity in very dilute solutions or in binary mixtures of gases,or for a constant gas mixture (e.g., air) and an impurity. Organicvapours in air can thus be determined if the refractive index of thevapour is known, or calibration curves are determined from knownmixtures.15 In the same way, the difference in refractivity betweenordinary water and a concentrate containing more heavy water is ameans of determining the proportion of heavy water rapidly and withan accuracy limited by the amount of water available and thelength of observation cell.With interferometers employing whitelight and an achromatic fringe as the zero of a drum reading, it isnecessary to take account of one serious error which may arise fromthe different dispersions of the glass compensator plates, the solution,and the standard water.16 Hence it is best to calibrate the drumof the instrument in such a manner as to give readings of the1 4 L. Szebellddy and H.Gml, 2. anal. Chem., 1934, 98, 255; A., 1190.16 H. Schildwiichter, Petroleum, 1934, 30, No. 11, 1 ; A., 619.16 R. H. Crist, G. M. Murphy, and H. C. Urey, J . Chem. PhysiCs, 1934, 2,112; A,, 618292 ANALYTICAL CHEMISTRY.apparent differences of refractive index against the correspondingdifferences in specific gravity. When all precautions are taken, theaccuracy with a cell only 4 cm. in length is about 0.01% of heavywater.Mention may be made of refractivity measurement for distin-guishing between different series of hydrocarbon^.^' The so-calledspecific dispersion is utilised; that is, the difference in refractiveindices for the Hg line A4358 and H, 16563, divided by the densityat 20". As an example, the value of this quantity x lo4 for paraffinsand naphthenes is about 157, while for olefins and unsaturatedcyclic hydrocarbons containing one double bond it is 185.Dielectric Constant in Analytical Determinations.-From time totime determinations of dielectric constant have been suggested-and sometimes applied-as an analytical method.It is obviousthat, given reliable means of ascertaining this physical constant,we would have an additional rheans of determining composition.For example, water in solids or certain liquids could be determinedwith some accuracy, or mixtures such as acetone or alcohol in benzene.The present position is that commercial apparatus is available formaking measurements with solids or liquids, and any " wireless "enthusiast could readily fit up an accurate apparatus. We havefound that with certain powders, the dielectric constant, or per-mittivity, varies directly with the proportion of water, but that thepermittivity calculated on the assumption that the powders may beregarded as a mixed dielectric consisting of anhydrous solid, water,and air, is not that found experimentally, although the slopes of thelines are nearly identical.18 It is further to be noted that, if salts arepresent in the powder, the curve for percentage of water-dielectricconstant may suddenly depart from a straight line with the higherproportions of water.Again, the method may be relativelyinsensitive as an analytical procedure with liquids whose dielectricconstants are close together, e.g., carbon tetrachloride and benzol.In such cases, the refractive index or even the density is moreaccurate.Nevertheless, the scope of the technical utility of deter-minations of dielectric constant has recently been widened 19 bythe use of dioxan as a solvent or dehydrating liquid. This substancehas E = 2.22 at 20", a value not far removed from other liquidswhich are free from dipoles, e.g., carbon tetrachloride, for whichE at 20" is 2.24. Its solvent power for organic liquids and for waterrenders it, specially valuable, since its degree of hygroscopicity maybe varied considerably by addition of non- hygroscopic liquids suchas paraffin oil. To illustrate the possibilities of the use of dioxan,l7 A. L. Ward and W. H. Fulweiler, Ind. Eng. Chern. (Anal.), 1934, 8, 396.l8 Unpublished work.lD L. Ebert, Angew. Chrn., 1934, 47, 305FOX. 293it may be pointed out that the addition of 1% of water increases thedielectric constant by about 12%, a substantial alteration, andcapable of ready and rapid measurement in modern apparatus.Amongst other investigations carried out with dioxan may bementioned the determination of adsorption (or desorption) equili-brium of surfaces.19 Dry dioxan is poured over the anhydrouspowder (e.g., a starch flour), a little water is added to the mixture,and the dielectric constant is determined on a portion of the filteredliquid from time to time, the determination occupying less than oneminute. With starch, a rapid adsorption occurred, followed by aslow adsorption lasting many hours.Presumably this kind ofinvestigation requires the dioxan to be present in very large excess.Dioxan mixed with diluents (paraffin oil) to reduce its power oftaking up water may be employed for the rapid determination ofwater in powders, the quantity of diluent used depending upon theadsorptive power of the powder, e.g., sand, active charcoal, cement.Further, the application of the method is not limited to water,but by selection of suitable diluents of higher dielectric constant,such as the alcohols, it is possible to determine other adsorbed, ormechanically held, substances of the nature of grease or solvent.It seems likely that the results obtained will be of the same order ofaccuracy as that of a refractometric method, but are not likely toreach the sensitivity obtained by the dipping refractometer, which isalso very rapid and needs but little liquid for test.Analytical Methods in Gas Analysis.-A few of the more importantdiscussions may be considered in relation to their practical bearing.The accuracy of vapour-liquid equilibria of binary mixtures whichdepart from the ideal laws of solutions is discussed in relation to theDuhem-Margules equation d log pl/d logpz = - (1 - x)/x, in whichx and (1 - x) are the molecular fractions of the components, xbeing the more volatile, and p l , p 2 are the corresponding partialpressures at some given temperature.20 This formula, may betransformed into a very similar one by using the “activitycoefficients ” as defined by Lewis and Randall (“ Thermodynamics ”) .Developments of the formule then lead to criteria by which theaccuracy of experimental data on partial vapour pressures may betested rigidly.Whenever rubber tubing and stopcock grease have to be used inthe analysis of gases, two possibilities of error may arise and shouldbe borne in mind.21 Hydrocarbons and carbon dioxide may beabsorbed by the rubber and grease, and some of these gases maybe given up when the apparatus is used again.Sometimes the20 H. A. Beatty and G. Calingaert, Ind. Eng. Chem., 1934, 26, 904.21 J. R. Branham, Bur. Stand. J . Res., 1934, 12, 353; A., 626294 ANALYTICAL CHEMISTRY.error is large, and if rubber cannot be avoided, it is necessary toascertain the losses by examining synthetic mixtures.Apart fiomthis source of error, there is the possibility of serious misinterpretationof results obtained by explosion of a gaseous hydrocarbon withcommercial oxygen (and even with pure oxygen) when the analysisis made by way of the determination of the contraction in volumeof the gas and oxygen or air mixture.Z2 If the results for an un-known mixture of pure ethane and air are computed as in an ordinarygas analysis, it is shown that substantial proportions of methanemay be reported from an interpretation of the results when none ispresent. Better results are obtained by slow combustion of thegaseous mixture. Attempts were made to shorten the time ofanalysis by more rapid combustion, but it appeared that theexperiments were more in the nature of stimulants to the operatorbecause of the possibility of disaster to the apparatus (and operator) ;so far as they went, however, the results were similar to thoseobtained by direct explosion.Small quantities of oxygen of the order of 0.07% in gas mixturesmay be determined by absorbing it in fresh alkaline pyrogalloland matching the colour produced against N/lO-iodine solution.Hydrocarbons and oxides of carbon do not interfere with thisdeterminati~n.~~ An exhaustive study of the accuracy of determin-ing oxygen by absorption with phosphorus has been carriedIt is suggested that, in the process of absorption, some intermediateform of oxygen other than ozone is present, this assumption beingnecessary to account for the observed oxidation of some hydrogenand carbon monoxide when these gases are present with oxygen inthe presence of moist phosphorus.It does not seem to the Reporterto be necessary to assume the presence of forms of oxygen otherthan that of atomic, or an activated form of molecular, oxygen a tthe surface of the phosphorus. The existence of oxygen in energystates as well as that of the normal gaseous state is well-enoughestablished and would be expected at the surface of phosphorus.In this sense it may be claimed that an intermediate substance 25is present in the reacting mixture. The fact that certain reactiveorganic molecules inhibit the oxidation of phosphorus is also under-stood if the effect of such substances is to form a molecular layer onthe surface of the phosphorus, or to take up the energy of activatedoxygen without combination. It is interesting to speculate whetherconsiderations of the oxidation of hydrogen at the surface of thephosphorus do not really afford an explanation of the striking result23 J.R. Branham and M. Shepherd, Bur. Stand. J. Res., 1934,13, 377.24 Idem, ibid., p. 593; A., 1186,H. R. Ambler, Analyst, 1934, 59, 14; A., 268.Ibid., p. 606FOX. 295that the extent of oxidation of hydrogen varies inversely as theproportion of oxygen in the gas under test.26In view of the increasing use of carbon monoxide in industry, it isimportant to know the purity of the commercial gas. A paper 27dealing with the analysis of this gas is therefore timely. Nitrogen,hydrogen, and methane were determined, and small proportionswere found.Iron carbonyl was also found in proportions varyingfrom 1 x 1W% to 1.5 x 1 P % , the quantity increasing with thetime the gas has been stored in the cylinder.A further study of the use of platinised silica gel in gas analysishas been undertaken,28 dealing in this case with the oxidation ofmethane, ethane, propane, and butane. Oxidation does not resultwith methane at 350", ethane at 230", propane a t 130°, or butane at120", but occurs at some 20-25" above these temperatures, althoughoxidation was not complete even at 400". Since hydrogen andcarbon monoxide can be quantitatively oxidised over the catalysta t 300", it follows that these two gases can be determined in thepresence of methane, but not when the other hydrocarbons arepresent, for they are likewise oxidised a t this temperature.Inthis connexion, earlier work on the temperatures for oxidation overcopper oxide should be studied.29A possible source of error in accurate work depending upon mano-metric measurements arises from an uncertainty in determiningcapillary depressions of mercury in cylindrical glass tubes of theordinary kind, because of a refraction error due to the glass. Inorder to eliminate these errors, thin-walled tubes are necessary forthe manometers, and a special design has been used.30 The relation-ship between capillary depression and height of meniscus for tubesof 10-19 mm. diameter and meniscus heights of 0-14 mm. hasbeen worked out and tabulated.The results are probably the mostaccurate available.Volumetric Xtandards.-Search for suitable secondary standardsfor volumetric analysis reveals certain novelties. Furoic acid canbe purified easily by crystallisation and sublimation, the acid ofm. p. 131" then being available as a pure materiaL31 When greataccuracy is desired, and in all those cases where trustworthy volu-metric solutions are required, the standardisation of hydrochloricacid by pure silver is indicated and has been employed in many16 H. R. Ambler, Analyst, 1934, 59, 696.27 H. R. Ambler and T. C. Sutton, ;bid., p. 809.28 K. A. Kobe and E. B. Brookbank, Ind. Eng. Chem. (Anal.), 1934, 6, 35.39 J. C. King and L. J. Edgcombe, Dept. Sci. Ind. Fuel Res., 1931, Tech.80 W.Cawood and H. S. Patterson, Tram. Paraday Soc., 1933,29, 514.81 H. B. Kellog and A. M. Kellog, Ind. Eng. Chm. (Anal.), 1934, 6, 251.Paper No. 33296 ANALYTICAL CHEMISTRY.laboratories. This is stressed in a recent paper 32 in which detailedinstructions are given for the use of silver as a primary standard.An unusual standard material for acidimetry is 3CdS04,8H,0, acrystalline substance readily obtained pure. This salt is dissolvedin water and electrolysed over a mercury cathode, thereby giving ttsolution containing the stoicheiornetric quantity of sulphuric acid,which is available for the standardisation of an alkali.33Comparison and Indicator Electrodes.-Silver halides, on silver orfused on to platinum wires, can be employed for comparison elec-trodes in potential measurements, or if combined with platinum orantimony electrodes, will function as indicator electrode^.^^ Forstabiliw in solutions to be titrated, the liquids should be treated withsodium chloride or with silver nitrate or sulphate.In precipitationreactions with phosphate, chromate, and oxalate, these electrodesare unsuitable because the solubility of the compounds of silverprecipitated is too high. A silver sulphide electrode can be usedadvantageously for sulphide precipitations, as with zinc deter-minations, or even for cyanometric titrations. For example, nickelin steel can be determined with a silver sulphide eleotrode, whereasa silver electrode fails on account of oxidation effects.Antimony sulphide electrodes have been prepared for pE measure-ments and are found to be available in the pE range 2-10 with anaccuracy of 5 0.05 unit.The electrodes are best prepared byheating antimony electrodes in 0.3N-nitric acid, and saturatingthe solution with hydrogen sulphide, in which the treated electrodesare stored until required.35 Other methods of preparing the sulphidecoating did not give such good electrodes. The liquid to bemeasured might contain starch, sugar, or nitrate ions withoutaffecting the accuracy, but hydroxy-acids, such as tartaric, renderthe electrode useless; but this applies equally to the antimonyoxide electrode. Although strongly alkaline solutions remove thesulphide film, the electrode still functions. J. J. F.2. GENERAL ANALYTICAL DETERMINATIONS.In the determination of metals by precipitation with 8-hydroxy-quinoline, followed by titration, it sometimes happens that theend-point is obscured by the formation of a brown cloudiness;this may be remedied by the addition of carbon disulphide to the83 C. W.Foulk and L. A. Pappenhagen, Ind. Eng. Chem. (AnaE.), 1934,6,430.33 S. E. Q. Ashley and G. A. Hulott, J . Amer. Chem. SOC., 1934,56, 1275.34 W. Hiltner, 2. anal. Chem., 1933, 95, 3 7 ; A., 1934, 48.35 T. R. Ball, W. B. Schmidt, andK. 5. Bergstresser, I&. Eng. Chem. (And.),1934,6,60; A., 267ELLIS. 297solution before adding the potassium iodide .1 Potentiometrically ,this bromination may be followed in 10% hydrochloric acid, pre-ferably at 50-55"; above 70" reaction is not stoicheiometric.2The precipitates obtained in acetic acid solution from thorium anduranyl salts with oxine are additive compounds containing onemolecule of the hydroxyquinoline.They are stable a t loo", butwhen heated at higher temperatures, the oxine is expelled; theresidues may be reconverted into their original form and colour, e.g.,by careful warming with oxine ~olution.~ The vanadium com-pound V,O,(C,H,ON), may be dried a t 100" and weighed; pre-cipitation in this form has been applied to steel analysis. Themolybdenum complex is insoluble in dilute acetic acid.* Zinc maybe determined in the presence of uranium by precipitation withoxine from alkaline tartrate or alkaline malate solution.5 In theseparation of iron and aluminium from beryllium with oxine, theaddition of oxalic acid may lead to error.6 In mixtures of iron,aluminium, calcium, and magnesium, the last is precipitated withoxine, after removal of the others, and then determined colori-metrically by coupling with diazotised sulphanilic acid, comparisonbeing made with similarly treated standards.' The aluminium insuch a mixture may be determined in a similar manner.8 Accuracyto 1% for 1 mg.of magnesium is claimed for a micro-modification ofBerg's volumetric m e t h ~ d . ~ For the determination of copperby means of 5 : 7-dibromo-8-hydroxyquinoline the procedure ofL. W. Haase l o is preferred.llCertain azo-derivatives of hydroxyquinoline are of value in de-tecting mercury(ic), palladium, and molybdenum (as MoOCI,")under specified conditions.l21 H. R. Fleck, F. J. Greenane, and A. M. Ward, Analyst, 1934,59,325; A.,J. A. Atanasiu and A. J. Velculescu, 2. anal. Chem., 1934, 97, 102; A.,F. J. Frere, J . Amer. Chem. Soc., 1933, 55, 4362; A., 1934, 82.791.791.* S. L. Tzinberg, Zavod. Lab., 1933, No. 1, 18; A., 1934, 1193.5 W. R. Wiggins and C. E. Wood, J. SOC. Chem. Ind., 1934,53, 254.1.; A.,6 V. M. Zvenigorodskajja and T. N. Smirnova, 2. anal. Chem., 1934,97,323;7 F. Alten, H. Weiland, and B. Kurmies, Angew. Chem., 1933,46,697; A.,* F. Alten, H. Weiland, and H. Loofman, ibid., p. 668; A , , 1933, 1263.9 G. Glomaud, J . Pharm. Chim., 1934, [viii], 19, 14; A., 270.10 2. anal. Chem., 1929,78, 113; A., 1929, 1159.11 J. V. Dubskjr and J.Chytil, Chm. Lbty, 1934, 28, 6 ; A., 382.12 G. Gutzeit and R. Monnier, Helu. C'him. Acta, 1933, 16, 478; A , , 1933,K 21085.A., 982.1933, 1262.732; cf. Ann. Reporta, 1933, 30, 281298 ANALYTICAL CHEMISTRY.With salts of gold and silver, tri(hydroxyethy1)amine formsmetallic mirrors, and with those of manganese, nickel, and cobalt,characteristic coloured soluble complex compounds ;I3 this basealso precipitates tin from an ammonium carbonate solution of tinand antimony in their higher state of 0xidati0n.l~The behaviour of bismuth with sulphur-containing reagents hasbeen investigated, e .g . , alkali thiocyanates, l5 thiourea,ls dimercapto -thiodiazole,l7 2-thiol-5-thio-4-phenyl-3 : 4-diazoloneYl* and numer-ous others.19 Dimercaptothiodiazole may be used for the separationof copper and lead from various other metals.20 Bismuth is extractedfrom most metals by a solution of diphenylthiocarbazone in chloro-form.21The metals which form insoluble pyridine thiocyanates may bedetermined indirectly by measuring the thiocyanate in the filtrate ;this may be effected potentiometrically 22 or by ordinary volumetricmethods.23 The precipitation of mercury as [Cu en,][HgI,], whichserves to separate this metal from members of the hydrogen sulphideand the ammonium sulphide may be followed potentio-metrically.25The perchlorate and picrate of methylene-blue are soluble inchloroform; this property may be applied to the determination ofmethylene-blue and picric acid 26 and of potassium, after precipit-ation as perchlorate or picrate.27With many metals quinaldinic acid forms salts, normal or basic,of varying solubility in acids ; 28 manganese is quantitatively pre-la E.Jaffe, Ann. Chim. appl., 1933, 22, 737; A., 1933, 246; Ind. china.,1934, 9, 151; A., 396; F. Garelli and A. Tettamanzi, ibid., 1933, 8, 577; A.,1933, 813.l4 Raymond, Compt. rend., 1934, 198, 1609; A , , 747.Is E. Tommila, Suomen Kem., 1934, 7, [B], 79; A., 502.l6 C. Mahr, 2. anal. Chem., 1934, 97, 96; A., 748.l7 J. V. Dubskf and A. OkM, ibid., 1934, 96, 267; A., 502.18 J. V. Dubskjr and J. Trtilek, ibid., p. 412; A., 622.Is J. V. Dubsk3, A. OkG, B. O b E , and J. Trtilek, i b d . , 98, 184; A., 1193.*O J. Gupta, J. Indian Chem. SOC., 1934, 11, 403; A., 982.21 L.A. Haddock, Analyst, 1934, 59, 163; A., 502.ra G. Spacu and P. Spacu, 2. anal. Chem., 1934, 90, 270; 97, 99, 192, 263;23 G. Spacu and M. Kur&, ibid., 99, 26; Bul. SOC. S$iin,te Cluj, 1934, 7,24 G. Spacu and G. Suciu, ibid., p. 183; A., 270.25 G. Spacu and I. G. Murgulescu, 2. anal. Chem., 1934, 96, 109; A., 270.28 A. Bolliger, J. Proc. Roy. SOC. New South Wales, 1933, 67, 240; A.,27 Idem, 2. anal. Chern., 1933, 94, 403; A., 47; J . Biol. Chern., 1934,107,2 8 P. Ray and M. K. Bose, 2. anal. Chem., 1933, 95, 400; A., 270.A., 502, 746, 747, 857.377; A., 1323.1017.229; A . , 1333ELLIS. 299cipitated from not too dilute neutral solution as anthranilate.29Precipitation of copper as oxalate with ammonia and oxalic acid isa good means of separating it from many other meta1s.W Iron,aluminium, and chromium are separated quantitatively from othermetals of the third group by means of ammonium ben~oate.~f Ascheme of qualitative analysis of the common metals of theammonium sulphide group utilising organic reagents has been workedPyrogallol, which has been suggested as a precipitant for anti-mony 33 and bismuth,34 gives colour reactions with cerium, thorium,lanthanum, and other elements of the third analyticalIron can be separated from beryllium by means of cupferron; 36details for the microanalytical determination of palladium withdimethylglyoxime, benzoylmethylglyoxime, and salicylaldoxime aregiven.37 Glycerol is oxidised in alkaline solution by mercury saltsbut by no other metals, mercury being quantitatively pre~ipitated.~~Owing to the formation of complexes with copper, cobalt, nickel,zinc, and cadmium, by addition of glycerol to solutions of thesemetals, free acid may be directly titrated with sodium hydroxideagainst methyl-0range.3~The colour of mixtures of sulphosalicylic acid and iron solutionsis influenced by pE, phosphate, bivalent manganese, and organicsubstances; most of these disturbances may be eliminated by theuse of citrate buffers and colour filters.40 The use of picrolonic acidfor colorimetric determination of calcium has been reviewed ; *lthis reagent has also been applied to the determination of lead.42Tin can be separated from many metals by precipitation withH.Funk and &I. Demmel, 2.anal. Chem.,1934,98, 385 ; A., 621 ; see Ann.3O A. Hemmeler, Ann. Chim. appl., 1934, 24, 140; A., 621; cf. Jakobson,31 I. M. Kolthoff, V. A. Stenger, and 13. Moskovitz, J. Amer. Chem. SOC.,32 L. Lehrman, H. Weisberg, and E. A. Kabat, ibid., p. 1836; A., 1192.83 F. Peigl, 2. anal. Chem., 1924, 64, 41; A., 1924, ii, 571.34 F. Feigl and H. Ordelt, ibid., 1925, 65, 448; A., 1925, ii, 442.S6 F. M. Schemjakin, 2. anorg. Chem., 1934,217, 272; A., 621.36 A. Tettamanzi, Ind. chim., 1934, 9, 752; A., 857.87 H. Holzer, 2. anal. Chem., 1933, 95, 392; A., 1934, 271.as M. Stschigol, ibid., 1934, 96, 328, 330; A., 621.3g H. Wagner, ibid., 1933, 95, 311; A., 1934, 162.40 F. Alten, H. Wieland, and E. Hille, 2. anorg. Chem,, 1933, 215, 81; A.,41 F. Alten, H.Wieland, and E. Knippenberg, Biochem. Z . , 1933, 285, 85;42 F. Hecht, W. Reich-Rohrwig, and H. Brantner, 2. anal. Chem., 1933,out .32Reports, 1933, 30, 282.Metal Id., 1921, 19, 380.1934,58, 812; A., 621.1934, 49.A., 1933, 1262.95, 152; A., 1934, 162300 ANALYTIC& CHEMISTRY.phenylamonic and iron similarly with p-n-butylphenyl-arsor-iic acid ; 44 zirconium and thorium, in particular, interfere.Much work is still being done universally on the determinationof sodium as triple uranyl acetate,45 and on the direct titration ofsulphate and barium with rhodizonic acid as i n d i ~ a t o r . ~ ~2-Aminopyridine gives characteristic crystalline compounds withsalts of cobalt, copper, zinc, and cadmium and alkali thiocyanate ; *'addition of thiocyanate and pphenylenediamine to neutral orammoniacal copper solutions produces a black complex compound.48Diphenyl-carbazide and -carbazone can be used as indicators inmercurimetric titrations ; 49 dithizone is applied to the detectionof zinc, after ' removal of cadmium, copper, and mercury,50 andqtxantitatively for lead and copper.51No entrainment of precipitant or metals occurs in the determin-ation of nitrate with nitron acetate ; 52 certain diphenylamineazo-dyes can be used as indicators in the titration of primary aminesby sodium nil~ite.5~The use of organic liquids as adjuncts to analytical manipulationis one which is receiving attention in these times no less than thatof organic reagents for precipitations or for colorimetric tests.Some such applications are of long standing as, e.g., the use of etheras a solvent for the extraction of ferric chloride from hydrochloricacid solutions or as an agent to promote agglomeration of silver43 J.8. Knapper, K. A. Craig, and G. C. Chandlee, J. Amer. Chem. Soc.,44 K. A . Craig and G. C. Chandleo, ibid., 1934, 56, 1278; A . , 858.4 5 E. R. Caley, C. T. Brown, and H. P. Price, Ind. Eng. Chem. (Anal.), 1934,6, 202; A., 745; T. Noda, J. SOC, Chem. Ind. Japan, 1933, 36, 6 3 5 ~ ; A.,1934,47; F. Alten, H. Weiland, and E. Hille, 2. Pflanz. Diing., 1933, 32, [A],129 ; r f . , 1934, 47 ; T. C. Chang and C. L. Tseng, Sci. Quart. Nut. Univ. Peking,1934, 4, 185; A . , 501; I. I. Nazarov and L. P. Banina, Zavod. Lab., 1934, 3,226; A., 857 ; S.Z. Makaxov and V. V. Bukina, J . Gen. Chem. Russia, 1933, 3,881; A., aOl.4 6 J. C. Giblin, Analyst, 1933, 58, 752; A . , 161; A. Friedrich and S. Rapo-port, Mikrochem., 1933, 14, 41 ; A., 1933, 1262 ; R. B. Roschal, Anilinokras.Prom., 1934,4, 37; A., 600; 31. I?. Maruschkin, J. Appl. Chem. Russia, 1933,6, 951; A . , 46; W. C . Schroeder, Ind. Eng. Chem. (Anal.), 1933, 5, 403; A.,1934, 46.1033, 55, 3945; A., 1933, 1263.4 7 A. Sri, Anal. Fawn. Bioquim., 1933, 4, 77; A., 1934, 502.48 R. J. McIlroy, Analyst, 1934, 59, 103; A., 382.49 J. V. Dubskf and J. Trtilelr, Chem. Liaty, 1933, 27, 385; A . , 1934, 49;Mikrochem., 1934, 115, 95; A., 744; J. Trtilek, Coll. Czech. Chem. Conzm.,1933, 5, 302; A., 1933, 1260.G. Rieniicker and W. Schiff, 2.anal. Chem., 1933, 94, 409; A., 48.51 H. Fischer and (Frl.) G. Loopoldi, Angew. Chem., 1934, 47, 90; A., 381.52 J. E. Heck, H. Hunt, and M. G. Mollon, Analyst, 1934, 59, 18; A,, 268.53 A. E. Porai-Kochitz and L. V. Tschervinskaja, Anilinokras. Prom., 1933,3, 339; A . , 1934, 161ELLIS. 301halide precipitates, of amyl alcohol as a solvent for lithium chloride,of ethyl alcohol in the separation of potassium and sodium asperchlorates. In the last example, it is suggested that the volumeof alcohol usually used for washing the perchlorates is insufficientto remove the sodium salt completely ; 54 accordingly, the proposalis made to double the volume, using alcohol saturated with potass-ium perchlorate in order to avoid loss. In the analyticalseparation of potassium chloroplatiriate by means of ethyl alcohol,reduction occurs if the latter contains acetaldehyde ; this con-stitutes a serious source of error in micro-analytical work where theamount of alcohol is relatively large.55 Potassium iodoplatinate isstill more sensitive.The most suitable solvent for the separationof sodium and potassium as iodides is a mixture of equal volumes ofisobutyl alcohol and ether, both anhydr0us.5~ Thallium may beseparated from most other metals by extracting with ether in thepresence of N-hydrobromic acid ; 57 a separation from gold, whichalso passes into the ethereal layer, is then described.The addition of gum tragacanth or gelatin prevents the turbiditywhich often occurs in the diethyldithiocarbamate process for minuteamounts of copper.58 As a solvent in this process, isoamyl alcohol,redistilled at 129-131", is preferred to the 7t-alcoh01.~~ I n theisoamyl alcohol modification of the thiocyanate method for smallquantities of ironY6O fading of the coloration has been experiencedas well as the introduction of undesirable colours due to calciumsalts; 61 the presence of nitric acid in place of other mineral acidassists in correcting both of these features.isoPropyl alcohol maybe used in place of ethyl alcohol as a solvent for analytical reagents,as a washing medium for precipitates, and for the separation ofinorganic compounds.62Ammonium salts give with sodium hypobromite and phenols54 M. Lenglen and Milhiet, Ann. Palsif., 1933, 26, 469; A., 1933, 1262.5 5 R.Strebinger and H. Holzer, 2. anal. Chem., 1932, 90, 81; A., 1932,6 6 L. Szebell6dy and K. Schick, Magyar Gybg. Tdrsas. $rt., 1933, 9 , 4 0 ; A.,67 I. Wada and R. Ishu, Sci. Papers Inst. Phys. Chem. Res. Tokyo, 1934,68 H. W. Moseley, A. G. Rohwer, and M. C. Moore, Science, 1934, 79, 507;XI R. W. Thatcher, J . Amer. Chem. Soc., 1933, 55, 4524; A,, 1934, 49.80 R. Stugart, Ind, Eng. Chem. (Anal.), 1931, 3, 390; B., 1932, 78.61 H. A. Daniel and H. J. Harper, J . Assoc. 08. Agric. Chem., 1934,17, 286;A,, 858.*2 G. W. Ferner and M. G. Mellon, Ind. Eng. Chem. (Anal.), 1934, 6, 345;A., 1193; cf. F. M. Archibald and C. M. Beamer, ibid., 1932, 4, 18; B., 1932,250.1222.161.24, 135; Bull. Inst. Phys. Chem. Res.Japan, 1934,13, 20; A., 857.A., 858302 ANALYTICAL OHEMISTRY.an intense blue coloration, turning red on acidification ; 63 that fromthymol may be extracted with organic solvents, e.g., ether. Othercations and organic bases (other than aniline) do not interfere.In qualitative tests involving the formation of insoluble com-pounds, sensitivity may frequently be increased by the addition of animmiscible liquid, causing the precipitate to collect a t the i n t e r f a ~ e . ~ ~Crystalline character and high molecular weight are features ofmany precipitates obtained by organic reagents from solutions ofinorganic substances. The analytical application of wholly in-organic compounds possessing these desirable properties is, therefore,not without interest.The reagent is a 10% aqueous solution ofpotassium mercuri-iodide which, when used for nickel or cadmium,should contain excess of potassium iodide. The precipitate fromcopper, in ammoniacal solution and in presence of ammoniumnitrate, has the composition [Cu(NH,),][HgI,], and contains4.91 yo of copper. The precipitates, though decomposed by wateralone, may be prepared for weighing by washing with alcohol,saturated with the appropriate compound, then with ether, and driedin a vacuum. Nickel may be separated from cobalt after oxidisingthe latter with hydrogen peroxide in the ammoniacal solution. 65Mercurous iodate is sufficiently insoluble to be utilised analytic-ally for mercury either gravimetrically or volumetrically ; 66 thereaction may also be followed potentiometri~ally.~7 Qualitativetests have been described for iodate and periodate in the presenceof each other.68Coagulation, filtration, and washing of barium sulphate are rapidwhen co-precipitation with aluminium hydroxide is effected. 69Organic Compounds.-The following reagents have been investi-gated for the purpose of identifying aldehydes and ketones :o- tolylh ydrazine , '* p - tolyl- and p - chlorophenyl- hydrazine, 7 l p-naph -thylhydra~ine,'~ phenylsemicarbazide, 73 p-tolylsemicarbazide, 746s L.Lapin and W. Hein, 2. anal. Chem., 1934, 98, 236; A., 1189.64 E.g., F. Feigl and H. Ordelt, ibid., 1925, 65, 448; A., 1925, ii, 442; Feiglet al., Mikrochem., 1931, 9, 165; A., 1931, 590.65 A. Tauring, 2. anal.Chem., 1934, 97, 27; A., 620.66 G. Spacu and P. Spacu, ibid., 96, 30; A., 270.e7 Idem, ibid., p. 188; A., 502.H. H. Willard and J. J. Thompson, J. Amr. Chm. Soc., 1934, 56, 1827;A., 1189.6s J. E. Orlov, 2. anal. Chem., 1934, 98, 326; A , , 1189.70 P. P. T. Sah and T. S. Ma, Sci. Rep. Nat. Tsing Hua Univ., 1932, [A], 1,71 P. P. T. Sah, H. H. Lei, and T. Shen, ibid., 2, 1, 7; A., 1933, 964.78 H. H. Lei, P. P. T. Sah, and C. H. Kao, ibid., p. 335; A., 1376.P. P. T. Sah and T. S. Ma, J . Chinese Ohem. SOC., 1934, 2, 32; A., 791.74 P. P. T. Sah and H. H. Lei, ibid., p. 167; A., 1016.259; A., 1933, 498ELLIS. 3033 : 5=dinitroben~oylhydrazine,~~ 3-nitro-, 76 o-~hloro-,7~ and p-chloro-benzoylhydrazine, 78 nitrobenzenesulplionhydrazine.79 2 : 4-Di-nitrophenylhydrazones of ketonic acids of biological importance havebeen characterised ; in view of the presence of traces of aldehydesin ethyl alcohol, 2 : 4-dinitrophenylhydrazine is best used in methyl-alcoholic solution.81 1 : 3-Dimethylbarbituric acid reacts rapidlywith furfuraldehydes and aromatic aldehydes.82Phenacyl and p-bromophenacyl esters of dibasic acids B3 and ofmonosubstituted benzoic acids 84 are described, a,ho aryl p-bromo-benzenesulphonates from phenols and the acid chloride in pyridine.85Some p-naphthyl ethers form picrates; 86 the use of styphnic acidas a reagent for the identification of aromatic compounds con-taining benzene nuclei,87 of heterocyclic nitrogen compounds, andof alkaloids 88 is recorded.react, as the potassio-derivatives, to give crystalline N-substituted derivatives with organichalogen compounds : akyl chlorides are readily converted intosubstituted amides via the alkylmagnesium compounds ; thep-toluidides are useful for distinguishing between chlorides of similarboiling p0int.~1 The list of sulphides obtained from mercaptans byreaction with 1 -chloro-2 : 4-dinitrobenzene has been extended.92Reactions of amines have been examined with a-naphthylthiocarb-3-Nitr0-~~ and tetrachloro-phthalimidel5 P. P.T. Sah and T. S. Ma, J . Chinese Chem. SOC., 1934, 2, 40; A.,76 K. C. Meng and P. P. T. Sah, ibid., p. 347; A., 1376.7 7 T. H. Sun and P. P. T. Sah, ibid., p. 359; A., 1376.l8 C. Shih and P. P. T. Sah, &id., p. 353; A., 1376.7* J.M. L. Cameron and F. R. Storrie, J., 1934, 1330.8O F. P. Clift and R. P. Cook, Biochem. J., 1932,26, 1800; A., 1933, 489.a1 J. Ferrante and A. Bloom, Anter. J . Phclrm., 1933, 105, 381; A., 1933,a2 S. Akabori, Ber., 1933, 66, [B], 139; A., 1933, 284.83 T. L. Kelly and P. A. Kleff, J. Amr. Chem. SOC., 1932, 54, 4444; A.,84 T. L. Kelly and H. W. Howard, ibid., p. 4383; A., 1933, 64.e5 V. C. Sekerrt, ibid., 1933, 65, 421; A., 1933, 270.88 A. B. Wang, J . Chinese Chem. SOC., 1933,1, 59; A., 1933, 1157.81 T. S. Ma, C. T. Hsia, and P. P. T. Suh, Sci. Rep. Nut. Tsing Hua Univ.,E 8 V. Hoo, T. S. Ma, and P. P. T. Sah, ibid., pp. 191, 245; A., 1934, 540,89 P. P. T. Sah and T. S. Ma, Ber., 1932, 66, [B], 1630; A., 1932, 1231.@O C. G. F. Allen and R.V. V. Nicholls, J . Amer. Chem. SOC., 1934, 56,91 H. W. Underwood, jun., and J. C. Gale, ibid., p. 2117; A., 1330.ga R. W. Bost, J. 0. Turner, and M. W. Conn, ibid., 1933, 55, 4956; A.,790.1053.1933, 52.1933, 2, 151; A., 1934, 540.1017.1409; A., 910.1934, 170304 ANALYTICAL CHEMISTRY.imide,Q3 ethyl sulphonediacetate,8* m-nitrophenylthi~carbimide,~~3 : 5-dinitroben~azide~~6 nitr~carbamide?~ 2 : 4-dinitrobenzoylData are given for various amides of hexoic acids and numerousesters of l-nitroanthraquinone-2-carboxylic acid ; the meltingpoints of some compounds of aldehydes with methone are revisedand the list e~tended.~In many of the above cases, improvements have been made inthe preparation of the reagents.The presence of bisulphite assists in the crystallisation ofosazones and hydrazones of sugar^.^The term ‘( aminometry ’’ is applied to the volumetric determin-ation of amines by acids with exclusion as completely as possibleof aqueous and alcoholic solvents and of all conditions under whichamines become bases ; 5 cinchonine and quinine behave quantita-tively as diacid amines, whereas strychnine and brucine are mono-acid.6 Salts of the last two yield precipitates with potassiumdichromate which can be dried to definite hydrates over deliquescentsodium bromide ; 7 strychnine, and brucine less satisfactorily,can be precipitated and weighed as hydroferrocyanide.Hexa-methylenetetramine can be determined by precipitation of itsuranyl double sulphate and argentometrically following precipit-ation with excess of silver nitrate.1°In the bromometric determination of furfural, temperature is93 C.M. Suter and E. W. Moffett, J. Amer. Chem. SOC., 1934, 56, 2497; A.,94 J. P. Alden and B. Houston, ibid., 1934, 56, 413; A., 396.96 P. P. T. Sah and H. H. Lei, J . Chinese Chem. SOC., 1934,2, 153; A., 997.Q6 P. P. T. Sah and T. S. Ma, ibid., p. 159; A., 997.s7 P. P. T. Sah, Sci. Rep. Nat. Tsing Hua Univ., 1934, 2, 227; A., 997.Qs C. A. Buehler and J. D. Calfee, Ind. Eng. Chem. (Anal.), 1934, 6, 351;Dg B. C. Saunders, Biochern. J., 1934, 28, 580; A , , 638.M. Hommelen, Bull. SOC. chim. Belg., 1933, 42, 243; A., 1933, 933.P. P. T. Sah and T. S. Ma, J. Chinese Chem. SOC., 1933, 1, 51; A., 1933,C. H. Kao and J. Y. Yen, Sci.Rep Nat. Tsing H m Univ., 1932, 1, 185;M. Wagenaar, Pharm. Weekblad, 1934,71,229; A,, 394; R. H. Hamilton,D. Vorliinder, J. Fischer, and F. Wildner, Ber., 1933, 66, [B], 1789; A,,D. Vorliinder, ibid., 1934, 67, [B], 145; A,, 314.I. M. Kolthoff and J. J. Lingane, J. Amer. Pharm. ASSOC., 1934, 23, 404;and, for amino-acids, 3 : 5-dinitrobenzoyl chloride.991933, 816.A,, 1240.1033.A., 1932, 1235.jun., J. Amer. Chem. SOC., 1934, 56, 487; A,, 394.1934, 198.A., 911.a Idem, ibid., p. 302; A., 672.Foucry, J . Pharm. Chim., 1934, [viii], 20, 168; A,, 1093.10 J. von Mik6, Pharm. Zentr., 1933, 74, 642; A,, 1934,175GLASSTONE. 305very important, since the secondary reaction (formation of tetra-bromide) has a high temperature coefficient.ll Furfural can bedetermined by precipitation with barbituric acid without inter-ference from hydroxymethylfurfural, which is not precipitated atthe concentrations encountered in the analysis of pentosans.l2Picric acid is quantitatively precipitated by ammoniacal solu-tions of copper sulphate; the reaction can be applied gravimetric-ally or volumetricaUy.13B. A. E.3. OXIDATION-REDUCTION INDICATORS.Although certain dyes, particularly methylene-blue, had beenused in volumetric work and in biological studies to indicate thepresence of a reducing agent, much as litmus was at one time usedto show the presence of acid, in recent years the study of oxid-ation-reduction indicators has developed to an extent parallel tothat of acid-base indicators.The applications of the former, likethose of the latter, fall into two categories : (a) in the determinationof oxidation-reduction potentials, and (b) in the indication of end-points in oxidation-reduction titrations.Oxidation-Reduction Potentials.-The oxidation-reduction in-tensity of a thermodymmically reversible system containing anoxidised and a reduced form is determined by the potential acquiredby an unattackable electrode when inserted in the solution underconsideration ; for the process represented bya A + b B + . . . + n O e x X + y Y + . . .the electrode potential E is given by the expressionE = E, + RT/nF . log, (a: . ut . . . )/(a% . a$. . . )where E, is the " standard oxidation-reduction potential " of thesystem, and the a terms represent the corresponding activities ofions or molecules.If neither oxidant nor reductant involveshydrogen ions, the electrode potential will be independent of theacidity of the solution, but will be determined by the ratio of theactivities (or concentrations) of the oxidised and reduced forms ;this is the case with the ferric-ferrous system, provided complex-forming organic ions, the concentrations of which are influenced bythe pE, are absent.l Many systems, especially those of biologicall1 E. E. Hughes and S. F. Acme, Ind. Eng. Chem. (Anal.), 1934, 6, 123;A , , 540; see also T. S. Krishnan, J . Indian Chem. SOC., 1934,11,651; A., 1337.l2 B. Peter, H. Thaler, and K. TLiufel, 2. Unters. Lebensm., 1933, 66, 143;A., 1933, 1278.1s A.Zacharov, J . Appl. Chern. Russia, 1933, 6, 998; A., 1934, 90.P. Hirsch and R. Ruter, 2. anal. Che.tn., 1926, 69, 193'; A., 1927, 23;L. Michaelis and E. Friedheim, J . BioE. Chern., 1931, 19, 343; A., 1931, 687306 ANALYTICAL CHEMISTRY.interest and those concerned with oxidation-reduction indicators,involve at some stage a thermodynamically reversible process inwhich hydrogen ions are concerned, and so the potentials in thesecases depend on the p , of the solution. In the simplest case, theoxidation-reduction equilibrium may be written : Q + 2H' +2 0 H,Q, and the electrode potential on the hydrogen scale isgiven byconcentrations being used instead of act'ivities for simplicity. Thepotential of a hydrogen electrode with gas at 1 atm. pressure in thesame solution will be R T / F .loge [H'], and thus the E.M.F. of ahypothetical cell consisting of such an electrode and the givenoxidation-reduction electrode should remain constant independentlyof changes in the pH of the medium. It is evident, therefore, thatthe latter electrode must be equivalent to a hydrogen electrodeoperating at a pressure P, determined by the relationshipThe hypothetical pressure P, and consequently a term rE, defined as- log P, should thus be a measure of the oxidation intensity of thesystem independent of the pH of the medium.2 The higher the rHvalue of a given system, the higher its oxidation-reduction intensity.So far, i t has been assumed that neither the oxidised nor the re-duced form has acidic or basic functions, but as the former is oftena quinone or a quinone-imine, the latter, at least, must containhydroxyl- or amino-groups ; the electrode-potential equation underthese conditions will include the various acidic and basic dissociationconstants of both oxidised and reduced state^.^ The r, for such asystem is no longer independent of the p , of the medium, and itdoes not adequately d e h e the oxidation intensity.The use of rHis thus liable to lead to confusion, and for this reason it should beused with caution.4 I n spite of its limitations, the rH is often con-venient for the description of biological systems : the pE of these isgenerally in the vicinity of 7, and if the r, is stated for this value itcan be regarded as remaining constant within the narrow limits ofpH variation likely to be encountered.5Oxidution-Reduction Indicators.-An oxidation-reduction in-dicator is, in general, a substaiice which in the oxidised state has aquinonoid structure and an intense colour ; on reduction it takes upflh = fl, + RT/2F - loge [Ql/[H~Ql+ R T / P .loge [H'],Eh = R T / 2 F . loge 1/P + RT/F . log, [H'].W. M. Clark and B. Cohen, U.S. Pub. Health Rep., 1923, No. 826.Idem, &id.W. M. Clark, US. Hyg. Lab. Bull., 1928, No. 151, Suppl. notes, p. 342;L. Michaelis, " Oxydations-Reductions Potentiale," 1933." The Determination of Hydrogen Ions," 1928GLASSTONE. 307two atoms of hydrogen per molecule, as in the simple examplealready considered, forming a feebly-coloured leuco-compound.If a small quantity of such a substance, which must attain equili-brium rapidly, is added to a relatively large amount of solutioncontaining an oxidation-reduction system to be examined, theindicator is either oxidised or reduced until its own potential,at the pa of the medium, is the same as that of the given system.The depth of colour shown by the indicator, which is determined bythe relative amounts of oxidised and reduced forms, will thus varywith the oxidation-reducfion potential of the solution being tested.If E,’ is the potential of the indicator system containing equimolaramounts of these two forms, at the pE of the medium, then theindicator will show an intermediate colour when placed in a solutionhaving the same potential. Small variations of potential on eitherside of E,’ will become evident by corresponding changes in thedepth of the indicator colour.An appropriate oxidation-re-duction indicator can thus be used to determine colorimetricallythe potential of a given solution, but as the indicators are generallyof the one-colour type, the results are only approximatee6 If oneindicator is decolorised by the solution and another not, then the Ehof the system lies between the E,‘ values for the two indicators a tthe pH of the s ~ l u t i o n . ~ Oxidation-reduction indicators are alsoused as “ potential mediators ” in biological media for which elec-trode equilibrium is only attained slowly ; the potential is thenmeasured electrometrically. When employing indicators for anypurpose it is essential that the solution t o which it is added shouldbe well “ poised,” i.e., buffered in the oxidation-reduction sense,so that in oxidising or reducing the indicator the ratio of oxidised toreduced states in the system under examination is not appreciablya1 t ered .I n order to determine the effective range of an indicator, a knownamount of the completely oxidised, or of the completely reduced,form is titrated electrometrically, using an inert electrode, with astandard solution of a powerful reducing, or oxidising, agentrespectively, in a series of buffer solutions of known p,; from the6 H.D. Gibbs, B. Cohen, and R. K. Caxinan, U.S. Pub. HeuZth Rep., 1925,No. 1001; A., 1926, 60.7 See, e.g., J. Needham and (Mrs.) D.M. Needham, Proc. Roy. SOC., 1925, [B],98, 259; A., 1925, i, 1012; idem, ibid., 1926, [B], 99, 173, 383; A., 1926,194, 545; B. Cohon, R. Chambers, and P. Reznikoff, J . Qen. Physiol., 1928,11, 586; A,, 1928, 793; R. Chambers, B. Cohen, and H. Pollack, Brit. J .Exp. Biol., 1929, 6, 229.8 W. M. Clark, U S . Pub. Health Rep, 1923, No. 823; A., 1923, ii, 677;M. Phillips, W. M. Clark, and B. Cohen, ibid., 1927, Suppl. No. 61; A., 1928,12308 ANALYTICAL CHEMISTRY.measured potentials, the value of E,’ at each p , is determined.g I nsome cases the results are extrapolated to pE 0 to give the standardoxidation-reduction potential E, of the indicator system. Analternative method of determining E,‘, which appears to be oflimited applicability, depends on the use of ‘‘ poised solutions,”made up from ferric and ferrous salts in the presence of oxalates, andfrom cupric and cuprous salts in potassium chloride solutions.1°The effective range of an indicator is often stated in terms of THcalculated from its E,’ potential at pH 7 ; although, as already shown,this is not a fundamental constant, it provides an approximatestandard of comparison for biological work.The indicator will beoxidised by a system having a higher rH, and reduced by one witha lower value.The majority of substances proposed as oxidation-reductionindicators are also acid-base indicators, being frequently blue inalkaline solution and reddish-brown in acid. The latter colour ismuch less intense than the former, and so it is desirable to use theindicator in the blue form.In biological work it is often not per-missible to alter the p , from the vicinity of 7, and hence indicatorsare required with relatively strongly acidic or weakly basic groups,so that they show their alkaline colours at relatively low pE values.This has been achieved in the phenol-indophenol series by intro-ducing halogen atoms into one of the phenolic residues.ll Morethan 70 coloured substances have been studied from the oxidation-reduction standpoint,12 but on account of their instability, sensitivityCf. W. M. Clark and B. Cohen, U.S. Pub. Health Rep., 1923, No. 834;A., 1923, ii, 726; M. X. Sullivan, B. Cohen, and W. M. Clark, ibid., 1923,No. 848; A., 1924, i, 321.lo P. Hirsch and R.Ruter, Zoc. cit.11 B. Cohen, H. D. Gibbs, and W. M. Clark, U.S. Pub. Health Rep., 1924,Nos. 904 and 915; A., 1924, ii, 597; 1925, i, 25; H. D. Gibbs, B. Cohen,and R. K. Cannan, Zoc. cit.l2 W. M. Clark and B. Cohen, Zoc. cit.; M. X. Sullivan, B. Cohen, and W. M.Clark, Zoc. cit. ; B. Cohen, H. D. Gibbs, and W. M. Clark, Zocc. cit. ; H. D. Gibbs,R. Cohen, and R. K. Cannan, Zoc. cit.; W. M. Clark, B. Cohen, and H. D.Gibbs, ibid., 1925, No. 1017; 1926, Suppl. No. 54; A., 1925, ii, 1164; 1926,1008; M. Phillips, W. M. Clark, and B. Cohen, Zoc. cit.; H. D. Gibbs, W. L.Hall, and W. M. Clark, ibid., 1928, Suppl. No. 69; A., 1929, 816; W. L. Hall,P. W. Preisler, and B. Cohen, ibid., 1928, Suppl. No. 71; A,, 1929, 769; B.Cohen and M . Phillips, ibid., 1929, Suppl.No. 74; A., 1930, 165; B. Cohenand P. W. Preisler, ibid., 1931, Suppl. No. 92; A . , 1931, 1013; -W. M. Clarkand M. E. Perkins, J . Amer. Chem. Soc., 1932, 54, 1228; A., 1932,472; R. D.Stiehler, T. T. Chen, and W. M . Clark, ibid., 1933,55, 891 ; A., 1933,464; R. D.Stiehler end W. M. Clark, ibid., 1933,55, 4097; A . , 1933, 1248; E. Vellinger,Arch. Phys. bioZ., 1929, 7, 113; L. Rapkine, A. P. Struyk, and R. Wumser,J . Chim. physique, 1929,26, 340; A., 1929, 1147; L. Michaelis, J . Bid. Chem.,1931, 91, 369; A., 1931, 687; ibid., 1931, 92, 211; A., 1931, 1309; J . AmerULASSTONE. 309to light, sparing solubility, or other disadvantages, only a limitednumber are suitable for use as indicators. The following have beenrecommended : indigo-disulphonate, -trisulphonate, and -tetra-sulphonate, met hylene- blue, t oluylene- blue, 1 -napht hol-2-sulphonateindo-2 : 6-dichlorophenol, l-naphthol-2-sulphonate indophenol, 2 : 6-dichlorophenol indo-o-cresol, m-toluylenediamine indophenol, 2 : 6-dichlorophenol indophenol, o-chlorophenol indophenol, phenol-o-sulphonate indo-2 : 6-dibromoindophenol, m-chlorophenol indo-2 : 6-dichloroindophenol, and phenol-m-sulphonate indo-2 : 6-di-bromophen01.l~ The range of E,’ values covered at p , 7.0 is from- 0.125 to + 0.273 volt at 30°, i.e., rH 10 to 23.For solutions withmore negative potentials the indicators available, mostly pheno-and apo-safranines,l* are not very satisfactory, but it is possiblethat the recently discovered “ vidogens,” which are NN’-disub-stituted-4 : 4’-dipyridylium chlorides,15 may prove of considerablevalue.These substances are remarkable in being coloured in thereduced state, the E,’ potentials being as low as - 0.4 voltat pa 7.Indicators in Volumetric Analysis.-When an oxidising agent iscoloured, it can often act as its own indicator in volumetric analysis :this is the case with permanganate and to some extent with iodine.Methylene-blue has been frequently used as a reagent in the titrationof titanous chloride, and a recent development of the same type isthe employment of 2 : 6-dichloro- (or -dibromo-)phenol indophenolas titrant for the estimation of vitamin-C.16 I n other instances,Chem. SOC., 1931, 53, 2953; A., 1931, 1129; Biochem. Z., 1932, 250, 564;A., 1932, 1102; L.Michaelis and H. Eagle, J . Biol. Chena., 1930, 87, 713; A.,1930, 1142; E. Friedheim and L. Michaelis, ibid., 1931, 91, 355; A., 1931,684; L. Michaelis, E. S. Hill, and 31. P. Schubert, Biochem. Z., 1932, 255, 66;A., 1933, 97; L. Michaelis and E. S. Hill, J . Gen. Physiol., 1933, 16, 589; A,,1933, 958; J . Amer. Chem. Soc., 1933, 55, 1481; A., 1933, 611; B. Elema,Rec. trav. chim., 1931, 50, 807; A., 1931, 1013; ibid., 1933, 52, 569; A.,1933, 909; 35. Lotort, Compt. rend., 1932, 194, 711; A., 1932, 343; E. Fried-heim, Biochem. Z , , 1933, 259, 257; A., 1933, 622; I<. G. Stern, Biochem. J . ,1934, 28, 949; A., 846; R. Kuhn and T. Wagner-Jauregg, Ber., 1934,67, [B],361; A., 461; see also K. G. Stern, ibid., p. 654; A., 817.13 W.L. Hall, P. W Preisler, and B. Cohen, Zoc. cit.; B. Cohen and M.Phillips, ZOC. cit.14 R. D. Stiehler, T. T. Chen, and W. M. Clark, Zoc. cit. ; R. D. Stiehler andW. M. Clark, Eoc. cit.1 5 L. Michaelis, Biochem. Z., 1932, 250, 564; A., 1932, 1102; L. Michaelisand E. S . Hill, Zocc. c i t .16 Cf. J. Tillmans, P. Hirsch, and R. Vaubel, 2. Uiater8. Lebensm., 1933,65, 145; A., 1933, 433; J. W. Birch, L. J. Harris, and S . N. Ray, Biochem. J.,1933, 27, 590; A., 1933, 646; J. L. Svirbely, ibid., p. 9qO; A., 1933, 872;A. H. Bennett, Analyst, 1934, 59, 91; A., 462310 ANALYTICAL CHEMISTRY.e.g., dichromate and ceric sulphate, external indicators or potentio-metric methods had to be applied for the determination of end-points.The application of the familiar fact that diphenylamine can be oxi-dised t o a violet-blue compound t o indicate the equivalence pointin the titration of ferrous iron by dichromate,17 has stimulated in-terest in the development of internal oxidation-reduction indicatorsfor use in volumetric analysis.The indicators already discussedare of little value in this connexion, because (a) their colour-changepotentials are too low, (b) the colours are relatively feeble in acidsolutions, and (c) they are relatively unstable.The indicator action of diphenylamine is to be ascribed to aprimary irreversible oxidation to diphenylbenzidine, followed byreversible oxidation of the latter, which is colourless, to diphenyl-amine-violet, with a green meriquinone as intermediate ; theholoquinone has an intense violet colour in solutions of low acidityand is blue in solutions which are more than 4N with respect tostrong acid. The marked colour change from green to violet occursa t about 0-76 volt (on the hydrogen scale) independently of theacidity of the solution.The rate a t which the violet colour developsin the presence of dichromate increases with the acidity, as does theoxidation potential, but with permanganate, which has a morepositive potential, the colour develops instantaneously at anyreasonable acidity.l* It was a t one time thought that the colourdevelopment required the presence of ferrous ions,lg but this isnot the case 2O although these ions increase enormously the rate a twhich the violet colour appears. I n the titration of ferrous ions bydichromate in acid solution the end-point is sharp provided phos-phoric acid or a fluoride is added ; 21 these substances form complexeswith the ferric ions and so reduce the potential of the ferric-ferroussystem below that at which the diphenylbenzidine colour changeoccurs.When diphenylamine is employed as indicator it is neces-sary to apply a correction, equivalent to the quantity of indicatorpresent, because of the oxidant used up in converting it into di-phenylbenzidine ; 22 this correction can be avoided by adding the1 7 J. Knop, J . Amer. Chem. SOC., 1924, 46, 263; A., 1924, ii, 351.18 I. M. Kolthoff and L. A. Sarver, ibid., 1930, 52, 4179; A., 1931, 54.1Q J. Knop, Zoc. cit.20 W. H.Cone and L. C. Cady, ibid., 1927,49,2214; A., 1927, 1046.21 J. Knop, loc. cit.; L. A. Sarver, ibid., 1927, 49, 1472; B., 1927, 657;L. Szebellbdy, 2. anal. Chem., 1930, 81, 97; A,, 1930, 1149; C. J. Schollen-berger, J . Amer. Chem. SOC., 1931, 53, 88; A,, 1931, 328.** N. H. Furman, Ind. Eng. Chem., 1925,17, 314; A., 1925, ii, 442; N. H.firman and J. H. Wallace, J. Amer. Chem. Soc., 1930, 52, 1443; A., 1930,727; L. A. Sarver and I. M. Kolthoff, ibid., 1931, 53, 2906; A., 1931,1141GLASSTON E . 311latter itself as indicator,23 but owing to its sparing solubility thisis rarely done. Diphenylbenzidine-violet suffers irreversible oxid-ation, forming an insoluble compound and leaving a colourlesssolution t o which the violet colour cannot be restored; 24 con-sequently, if the indicator is to be used for back titrations the timeof contact with the oxidising solution should be kept at a minimum.Although it was first considered that diphenylamine could be usedin the presence of mercuric ionsY25 it has been shown that theyinhibit the formation of the violet colour,26 and even traces oftungstate ions exert a similar effect.27 Many of the disadvantagesof diphenylamine itself can be avoided by the employment of thesulphonic acid, as its barium salt.This is readily soluble in acidsolutions and it changes colour a t a potential of about 0.83 volt,in a manner similar to that of diphenylamine. The presence offerrous ions accelerates the normally slow transition from green toviolet, and a sharply reversible brilliant colour change occurs at theend-point in the ferrous-dichromate titration which is not maskedeven in coloured solutions.Mercuric ions and tungstate ions haveno influence on the development of the violet colour under theseconditions.28 The correction for the oxidation of the indicator islarger than would be expected theoretically, but the difference isnot serious if only a small amount of indicator is used.29 I naddition t o the ferrous-dichromate titration, diphenylamine (or itssulphonic acid) has been employed in the following titrations :ferrous ions by permanganate,30 by vanadateY31 and by ceric23 W. H. Cone and L. C. Cady, J . Amw. Chem. SOC., 1927, 49, 356; A,,1927, 331; I. M. Kolthoff, Chem. Weekblad, 1927, 24, 203; A., 1927, 535;H.H. Willard and (Miss) P. Young, J . Amer. Chem. SOC., 1928, 50, 1334; A.,1928, 725; I. &I. Kolthoff and L. A. Sarver, ibid., 1930, 52, 4179; A., 1931,64; I. M. Kolthoff and E. A. Pearson, I d . Eng. Chem. (Anal.), 1932, 4, 147;A., 1932, 243.24 I. M. Kolthoff and L. A. Sarver, loc. cit.25 J. Knop, loc. cit.; W. W. Scott, J . Amer. Chem. Soc., 1924, 46, 1396;l6 F. J. Watson, Chem. Eng. Min. Rev., 1928, 20, 355; I. M. Kolthoff and*’ H. H. Willard and P. Young, Ind. Eng. Chem., 1928, 20, 769; B., 1928,28 L. A. Sarver and I. M. KoIthoff, J. Amer. Chem. Soc., 1931, 53, 2902;28 Idem, ibid., p. 2906; A., 1931, 1141.30 w. w. Scott, loc. cit.31 N. H. Furman, loc. cit.; H. H. Willard and P. Young, ibid., 1928, 50,1334; A,, 1928, 725; Ind.Eng. Chem. (Anal.), 1933, 5, 164, 168; B., 1933,650; L. A. Sarver and I. M. Kolthoff, ibid., 1931, 53, 2906; A., 1931, 1141;K. Someya, 2. anorg. Chem., 1924, 139, 237; A., 1925, ii, 161; see, however,icEem, ibid., 1926, 152, 391; A., 1926, 705.A., 1924, ii, 787.L. A. Sarver, loc. cit.643.A., 1931, 1141312 ANALYTICAL CHEMISTRY.sulphate ; 32 chromic acid by titanous sulphate ; ferricyanide ions bystannous chloride ; uranous ions, cuprous ions in hydrochloricacid, iron-chromium mixtures,33 and ferrocyanide ions 34 bydichromate; zinc ions by ferrocyanidea5 containing a trace offerricyanide ; and quinol by ceric sulphate and by dichromate.36A general study has been made of a number of diphenylaminederivatives, of which the most interesting are the pnitro-, p-amino-,and 2 : 4-diamino-compounds.The last changes colour from greent o violet a t about 0.66 volt, and the violet holoquinone is relativelystable to further oxidation ; 37 this substance may therefore findapplication for back titrations. Other substances analogous todiphenylamine in their oxidation-reduction properties 38 have alsobeen used as indicators ; p-anisidine, p-phenetidine, and di-o-anisidine, of which the last is the best, have been employed in thetitration of ferrous ions by dichromate ; 39 benzidine 40 and benzidineacetate 41 for ferrocyanide titration by dichromate ; p-phenetidinefor dichromate against ferrous ions ; 42 and pp’-diaminodiphenyl-amine 43 for barium chloride and dichromate.The following triphenylmethane dyes have been recommendedfor use in titrations with permanganate, their oxidation potentialsbeing too high for employment with dichromate : acronol brilliantblue BDC, cyanine B, cyano bright green 2G, erio-glaucin A, erio-green B, patent blue A, setocyanine supra, setoglaucin 0, setopalinconc., xylene blue AS, xylene blue VS, and xylene cyanol FF.These substances are apparently first oxidised irreversibly to com-pounds of unknown constitution which act as truly reversible indi-cators : the colour change on oxidation is from yellow or green topink, in the presence of acid, and is so marked that titrations may32 H.H. Willard and P. Young, Zoc. cit. ; see also N. H. Furman and J. H.Wallace, J . Amer. Chem.SOC., 1930, 52, 2347; A., 1930, 1012.33 K. Sorneya, 2. anorg. Chem., 1926, 152, 368, 382, 386; 1927, 160, 355,404; 1927,163, 206; A., 1926, 702, 705; 1927, 332, 333, 746.34 A. J. Berry, Analyst, 1929, 54, 461 ; A., 1929, 1159.1927,24, 203; 1929,26, 298; A., 1927, 535; 1929, 785.and J. H. Wallace, J . Amer. Chem. SOC., 1930, 52, 1443; A., 1930, 727.1092; A., 744.Suppl. No. 54; A., 1926, 1008.W. H. Cone and L. C. Cady, Zoc. cit.; I. M. Kolthoff, Chem. Weekblad,86 Idem, Rec. trav. chim., 1926, 45, 745; A., 1926, 1266; N. H. Furman37 L. P. Haminott, G. H. Walden, and S. M. Edmonds, ibid., 1934, 56,38 W. M. Clark, B. Cohen, and H. D. Gibbs, U.S. Pub. Health Rep., 1026,M. E. Weeks, Ind. Eng. Chem. (AnaZ.), 1932,4, 127; A , , 1932, 244.40 I. M.Kolthoff, Chem. Weekblad, 1924, a, 2 ; A., 1924, ii, 121.F. Sierra and F. Burriel, AnaZ. Pis. Quim., 1932, 30, 441 ; A., 1932, 924.43 L. Szebelledy, Zoc. cit.43 H. Roth, 2. angew. Chem., 1926, 39, 1599; A., 1927, 125GLASSTONE. 313be made in highly coloured solutions. The indicators recommendedmay be used for titration with permanganate of solutions containinghydrochloric acid provided manganous sulphate is added, and theirsensitivity is not affected by mercury salts. The addition of phos-phoric acid in the titration of ferrous salts is unnecessary. Thecorrection to be applied for the oxidation of the indicator (0.5-1C.C. of a 0.1% solution) is negligible when 0-1N-permanganate isthe t i t r a ~ ~ t . ~ ~ . All of the dyes mentioned, except acronol brilliantblue BDC and setoglaucin 0, can be used for the microtitration offerrous ions by ~ermanganate.~~ Erio-glaucin A and erio-gre-en Bhave also been applied in the titration of ferrocyanides by perman-ganate,46 and both of these as well as cyanol blue FP have beenrecommended as indicators for usc with ceric ~ulphate.~’ Theresults are satisfactory either in hydrcchloric or sulphuric acid solu-tions, and mercury and tin salts do not interfere with the sensi-tivity of the indicators.An indicator of a different type is the o-phenanthroline ferrousion Fe(C1,H8N2)3.*, which, with the corresponding ferric ion,Fe( C12H8N2)3m*., forms a reversible oxidation-reduction system inwhich the reduced state has a very intense red and the oxidised statea relatively feeble blue colour, so that there is a marked colourchange in the vicinity of 1.1 volts from red almost to colourless orvice versa, on oxidation or reduction, respectively.The compoundsare not susceptible t o destruction by further oxidation, and o-phenanthroline ferrous sulphate lends itself particularly for use asindicator in titrations of ferrous ions with dichromate and withceric ~ulphate.~* Since the colour change occurs a t a potentialmore positive than that of the ferrous-ferric system, the additionof complex-forming ions (phosphate or fluoride) is unnece~sary.~~The indicator has also been employed in the titration of ferro-cyanide, thallous, arsenious, quaclrivalent uranium, oxalate,vanadate, and nitrite ions and hydrogen peroxide by means of cericsulphate;50 of vanadate ions alone or in the presence of ferric,44 J.Knop, 2. anal, Chem., 1929, 77, 111; 1931, 85, 253; A,, 1929, 670;J. Knop and 0. Kubelkovti, ibid., 1929, 77, 125; A., 1929, 1931, 1256;670.45 Idem, ibid., 1931, 85, 401; A., 1931, 1261.‘6 Idem, ihid., 1929,”, 125; A., 1929, 670.4 7 N. H. Furman and J. H. Wallace, J . Amer. Chem. SOC., 1930, 52, 2347;A., 1930, 1012; A. D. Mitchell and A. M. Ward,, “Modern Methods inQuantitative Chemical Analysis,’’ 1932.48 G. H. Walden, L. P. Hammett, and R. P. Chapman, J . Amer. Chem. SOC.,1931, 53, 3908; A., 1931, 1385.49 Idem, ibid, 1933, 55, 2649; A., 1933, 924.50 H. H. Willard and P. Young, ibid., p. 3260; A., 1933, 1025314 ANALYTICAL CHEMISTRY.chromium, or molybdenum compounds by ferrous sulphate ; 51 andof ferrous ions alone or in the presence of vanadium, titanium,chromium, or manganese with ceric ~ u l p h a t e .~ ~ The use of thenitrophenanthroline ferrous ion as an oxidation-reduction indicatorhas also been proposed; 53 its oxidation potential is about 0.1 voltmore positive than that of the o-phenanthroline ferrous ion and soit is doubtful if it can be applied to dichromate titrations.I n addition to the use in volumetric work of the reversibleindicators already described, a number of dyes which undergoirreversible oxidation at high positive potentials have also beenemployed. The application of methyl-orange and met,hyl-red inbromate titrations is well known,54 a.nd it has been found that thesesubstances, in addition to met hylene- blue, Congo-red, 55 malachite-green and methyl-violet,56 can be used as internal indicator for theestimation of ferrous and antimonious compounds, oxalates, andquinol by ceric sulphate.S. G.4.MICROANALYSIS.As micro-methods now cover the whole range of analyticalchemistry, the advances in only a few selected branches of thesubject will be described.“Spot ” Tests.-The growth and application of spot tests is oneof the most important of the recent developments in microchemistry.Originally these were colour tests for various inorganic ions, but manyhave now been found to be suitable for quantitative work, and theyhave also been extended to organic chemistry. The tests are gener-ally carried out on a white tile or spot plate, in test-tubes of varioussizes, or, in the majority of cases, on thick, close-grained, filterpaper.The use of filter paper renders possible the separation ofelements by filtration through the pores of the paper, and, in somecases, the simultaneous identification of elements in different zones51 0. H. Walden, L. P. Hammett, and S. M. Edmonds, J. Amer. Chem. Soc.,52 Idem, ibid., p. 350; A., 382.53 L. P. Hammett, G. H. Walden, and S. M. Edmonds, ibid., p. 1092; A.,744.54 For other suitable indicators, see G. F. Smith and H. H. Bliss, ibid., 1931,53, 2091, 4291 ; A,, 1831, 925; 1932, 137.K c H. Rathsburg, Ber., 1928,65, [B], 1663; A,, 1928, 1207; H. H. Willardand P. Young, J . Amer. Chem.SOC., 1928, 50, 1322; A., 1928, 725; N. H.Furman and J. H. Wallace, ibid., 1930, 52, 1443, 2347; A., 1930, 727, 1012;N. H. Furman, ibid., 1932, 54, 4235; A., 1933, 43; see also K. Someya,2. anorg. Chem., 1928,169, 293 ; A,, 1928, 387.66 R. Vanossi and R. Ferramola, Anal. Asoc. Quz’m. Argentina, 1932, 20,96; A., 1933, 138.1934, 56, 57; A., 257MATTHEWS. 315of the paper owing to variations in diffusion rates or solubility.When the filter paper is impregnated with a solution of the reagentin a volatile solvent, it may often be dried and kept indefinitely,and is obviously especially useful in field work and all tests awayfrom a laboratory. Usually the test is carried out on a single dropof solution, the concentration varying according to the sensitivityof the test from about 1 : 1000 t o 1 : 2,000,000; when working intest-tubes, however, as much as 1 ml.of the test solution may some-times be taken. The limit of identification in spot tests ranges froma few gamma (y) t o a few thousandths y. Many spot tests are specificwhen carried out in suitable conditions, and this number is rapidlyincreasing.Spot tests for organic compounds. A large proportion of spottests involves the use of organic reagents, and in the investigationof these, certain organic groupings are found to react with certaininorganic ions, and this has led to the development of spot testsfor organic radicals by utilising the tests in the reverse manner withthe inorganic ion as the reagent. Only a limited number of thesetests are suitable, and in general, they are considerably lesssensitive than the tests for the inorganic ions.At the same time,however, a number of macro-tests are being applied on the micro-scale with great saving in time and trouble. This spread of spottests to the whole field of organic qualitative analysis is a mostimportant recent development.Tests at present available 1. include those for elements present inorganic compounds, and also for the following radicals and com-pounds : NO and NO,, CO, CHO, CH3*C0, C:C*CHO, C:S and C*SH,CO,H*C-C*CO,H, SO,H, NH,, NH, NMe, ArNH,, N-NH,, CH,,NH,, alcohols, phenols, enols, carbonic acids and their derivatives,and tertiary ring bases. There are also spot tests for a numberof individual organic compounds, among which are lactic, oxalic,malic, tartaric, and citric acids, glycerol, tyrosine, pyridine, andothers.The sensitivity of these tests ranges downwards from about100 y to a few hundredths y.It is to be realised that, apart from the organic spot tests mentionedhere, there has been a great deal of other work carried out in organicqualitative analysis, notably in the detection of the alkaloids andmany pharmaceutical products, mainly using tests involving1 (i) F. Feigl; (ii) F. Feigl, V. Anger, and 0. Frehden; (iii) F. Feigl andV. Anger, Mikrochem., 1934, 15, (i) 1, (ii) 15, (iii) 23; A., 790. (iv) F. Feigl,V. Anger, and 0. Frehden; (v) F. Feigl, V. Anger, and R. Zappert, ibid., pp.181, 190; A., 1239; (vi) F. Feigl, V. Anger, and R.Zappert; (vii) F. Feigland 0. Frehden, ibid., 18, 67, 79; A., 1240; I. M. Korenman, J. SOC. Chem.Ind., 1931, 8, 608; F. Feigl, ‘‘ Qualitative Analyse mit Hilfe von Tupfolreaktionen,” 2nd Edn., 1935, 354316 ANALYTICAL CHEMISTRY.crystal formation and investigation under the microscope, melting-point determinations under the microscope, sublimation, and othermet hods of preparative microchemistry.Applications to quantitative analysis. Spot tests have been usedfor approximate quantitative work by matching colours of spotson paper or a white tile with those from standard solutions, and areuseful in some routine investigations and especially in plant and soilwork. The accuracy has been investigated for the estimation ofcopper, silver, lead, manganese, tin, zinc, and magnesiuin.2 Thefollowing are some of the reagents first used for spot tests whichhave been successfully applied to accurate colorimetric work :p-dimethylaminobenzalrhodanine (Ag), diphenylcarbazone (Hg),sodium diethyldithiocarbamate (Cu), salicylaldoxime (Cu), thiogly-collic acid (Fe), m'-dipyridyl (Fe), diphenylcarbazide (Cr), aurine-tricarboxylic acid (Al), dithizone (Pb, etc.), p-nitrobenzeneazoresorc-inol (Mg).Occasionally, the precipitations in spot tests are sufficientlycomplete for use in micro-gravimetric analysis, with low-temper-ature drying of the product. An example of this is given in the use ofrubianic acid as a reagent for the determination of palladium andother metals of the platinum group.4Spot tests for inorganic ions.The number of spot tests of thetype first to be developed, those for inorganic ions, is rapidly in-creasing. Recent work includes the tests mentioned below :A new test for beryllium, using p-nitrobeiizenea,zo-orcinol, is sensitiveto O.2yBe in 1 : 200,000 d i l ~ t i o n . ~ A sensitive reagent for boricacid is pnitrobenzeneazochromotropic acid (Chromotrope 2B),6by means of which 0-OSyB in 1 : 500,000 dilution can be detected;special precautions are taken in the presence of oxidising anions andof fluorides. A variation in the curcumarin test for boronis also described.' A test for copper depends on the identi-fication with 8-hydroxyquinoline of the cyanogen liberatedby copper salts and potassium cyanide, and is sensitive to 0 .4 ~ . ~A similar, but somewhat more sensitive, test for Jluorine than the2 J. Kisser and K. Lettmayr, Ilililcrochern., 1932-33,12,235; A., 1933, 137.3 H. Fischer, Angew. Chem., 1934, 47, 685; A., 1191; H. Muller, Mikro-chem., 1932-33,12, 307; B., 1933, 366; N. Strafford, Institute of ChemistryPublication, 1933 (summary and collected references) ; L. H. Cooper, Chem.and Id., 1934, 53, 830.4 H. Wolbling and B. Steiger, Mikrochent., 1934,15, 295; A,, 1193.5 A. S. Komarovsky and N. S. Poluektov, ibid., 14, 315; A,, 746.7 N. A. Tananaev and 0. A. Kulska, Ukrain. Chem. J., 1934,9,1.8 A. S. Komarovsky and N. 5. Poluektov, Z. anal. Chern.., 1934, 96, 23;Idem, ibid., p. 317; A., 745.A., 270MATTHEWS . 317zirconium-alizarin test is that with zirconium p-dimethylamino-azophenylarsonate: whereby the interference of fluorine ions inthe test, when used for the identification of zirconium, is utiliscd,and 0.25yF in 1 : 200,000 dilution may be identified.A simpletest for $uorine by the etching of glass has also been used as a spottest; 06yF in 1 : 100,000 dilution can be identified.lO Whenmanganous salts (in the absence of chromates) are oxidised to per-manganate with alkali periodates, invisible amounts of perman-ganate, down to 0.OOlyMa in 1 part in 50 million dilution, canbe detected by the blue colour on addition of a solution of Arnold’sbase (tetramethyldiaminodiphenylamine) in chloroform.11 Nitrousacid in the presence of nitrates can be detected down to 0 . 2 5 ~ bymeans of chrysean (Z-aminothiaz0le-4-thioamide).~~ Useful testsfor selenium and tellurium in the presence of each other are de-scribed,13 whereby 1 part of selenium in the presence of 615 parts oftellurium, or 1 part of tellurium in 100 parts of selenium, can beidentified.A specific test for potassium among the elements of thefourth and fifth groups of analytical separations, except rubidiumand czsium, uses p-dipicrylamine l4 (hexanitrodiphenyIamine) as areagent, and detects 3yK in 1 : 10,000 dilution.Quantitative Analysis on the ‘‘ Gamma ” Scale.-A considerableamount of accurate work has recently been carried out, mainly appliedt o biology-in the study of enzymes, in the examination of smallplants and animals, and in medical research.Much of this work isvolumetric (apart from purely physical methods such as spectro-metric and polarographic methods, and others, not dealt with here)and the accuracy is largely obtained by the use of suitable micro-burettes and -pipettes. Linderstrom-Lang l5 uses home-madecapillary pipettes of two types, the one to deliver amounts of theorder of 0.007 ml., with an error of less than 0*3y0, and the othertype for larger volumes of the order of 0-03 ml., with an error ofless than 0.1%. Both are constructed to deliver the liquid undera pressure of water (20 cm. of water in 7 seconds, and 50 cm. ofwater in 22 seconds, respectively). Kirk16 also uses capillarypipettes of capacities ranging from 0.01 to 0.2 ml., and controIs thedelivery by means of the pressure from a hypodermic syringe.9 F.Feigl and E. Rajmann, Mikrochem., 1932,12, 133; A., 1933, 135.10 S. K. Hagen, ibid., 1934, 15, 313.11 F. Feigl and L. Weidenfeld; see F. Feigl, OP. tit., p. 228.12 J. V. Dubsky, J. Trtflek, and A. OkAE, Mikrochem., 1934, 15, 99.13 N. S. Poluektov, ibid., p. 32.14 Idem, ibid., 1933-34,14, 265.15 I(. Linderstrom-Lang and H. Holter, Compt. rend. Truv. Lab. Carbberg,16 p. L. Kirk, Mikrochem., 1933-34, 14, 1 ; A., 1933, 1262.1931, 19, (4)) 1318 ANALYTICAL CHEMISTRY.The best micro-burettes are usually of the Brandt-Rehberg type,17z'ix., a capillary burette, the titrating liquid being above a thread ofmercury. The burette is filled or emptied by the operation of a metalscrew which raises or lowers the level of the mercury.Linderstrom-Lang utilises a burette of this type five times as fine as the original,with or without an air gap between the mercury and the titratingliquid according to its stability towards mercury. His burette hasa total volume of 0.1 ml. and is graduated in 0-0002 ml. ; one-tenthof this can therefore be estimated. Where a micrometer screw isfitted, this is used as a more accurate means of reading the volumethan the mercury level. Kirk16 also uses this type of burette,with capacities of 0-1-0.2 ml., but to simplify matters in the event ofbreakage, the burette has a detachable tip attached with rubbercement, and fixed outside by means of two brass collars with anopen-sided coupling between them to draw the collars together.He also uses a burette of the same type as the syringe pipette, butwith a coil spring to prevent back-lash.Schwarz l8 has devised asimpler model of burette without mercury or metal screw (for volumesof the order of 0.2 ml.) with an accuracy of 0.1-0.2~0. This is onthe wash-bottle principle, and uses suction and blowing for fillingand emptying the burette.On the small scale the stirring is usually electrical, onemethod being to use sealed capillaries, 1-14 mm. in length, filledwith reduced iron, and to agitate these by means of an electro-magnet periodically switched on and off.15 The stirring may alsobe carried out by using a very fine-tipped capillary, also agitatedelectrically by means of an electromagnet through which a 60-cycleA.C.current is psssing.16 I n micro-potentiometric work, one ofthe electrodes may be used as the stirrer, agitated in the samemanner .laSome form of adjustable titration table simplifies the use of theabove apparatus, which will give very accurate results in theanalyses of small amounts of material. The titration is carried outeitherin micro-beakers consisting of narrow Jena-glass tubes l5 (about2-26 cm. high and 0.4 cm. internal diameter), or in depressions onmicroscope slides,16 or, in potentiometric work, in a small drop on aring made of a metal suitable for the determination.18 The meanpipetting and titration error as determined by simple titrations is0.07 and a little greater in determinations of small cleavagescaused by enzymes.Calcium has been determined on amounts ofthe order of 57 with errors of less than 1 yo (a precipitation and filtra-tion also being involved), and the determination applied to the1 7 P. Brandt-Rehberg, Biochem. J., 1925, 19, 270.18 K. Schwarz, Mikrochem., 1933, 13, 1 ; A., 1933, 686MATTHEWS. 319calcium in blood serum or plasma using only about 0.02 ml. ofsample.19 Potentiometric titrations, using a silver electrode for thedetermination of 1-2yC1, 0-04-0.4yBr, or &5yAg, have beencarried out with similar errors of less than l%.18 Potentiometricdeterminations of a few y of iron, lead, and arsenious acid have alsobeen carried out with the same accuracy,l* and by special refinementsof technique the determination of chlorides has been carried toeven lower limits of 0.005y with errors of less than 5y0,20 and of1-100y of mercury with errors of the order of 1yo.21In the determination of very small amounts of sugars22 and ofammoniaY23 the micro-beakers are thinly coated with paraffin, sothat drops of liquid placed one above the other do not mix untilstirred.I n the sugar determination, the buffer solution, sugarsolution, and iodine are mixed at the bottom of the vessel, andevaporation of iodine is prevented by two films above the surface ofthe liquid, one of 0-05 ml. of l.2N-sulphuric acid, and one of starchsolution in N/lOO-sulphuric acid. The reaction tube can safely beleft until the reaction is at an end, then the mixture is centrifuged,and the liquid titrated against N/20-thiosulphateY the accuracybeing about 2.5 x lo4 mg.of glucose.Ammonia is determined by the film method by mixing the testsolution with a drop of 2N-caustic soda, and a film of the absorbingacid is placed above. On being left for sufficient time in an in-cubator at 40°, the ammonia distils into the acid, and the excessacid is titrated with borate (for quantities less than 0.2 x 10-6 mol.)or alkali (for larger quantities) without causing the drops to mixwith the alkali underneath. On amounts of 0.5-2yN, errors ofless than 1% were obtained.Complete micro-Kjeldahl determinations (Le., digestion in-cluded) on organic material containing 4--16yN with a mean errorof 1 yo have been carried out by modifying the usual micro-Kjeldahlprocedure .24Gravimetric determinations on this small scale can only be under-taken with a balance of greater sensitivity than the usual Kuhlmannmicro-balance. This has been done for simple residue determin-ations on initial weights of substance varying from 2 to lOy, witherrors of about 0.2y0, using Emich’s electro-magnetic micro-balance,ID P. L. Kirk, Nikrochem., 1933-34,14, 15; A., 1933, 1262.20 K. Schwarz and (the late) C. Schlosser, ibid., 1933,13, 18; A., 1933, 582.21 K. Schwarz and T. Kantor, ibid., p. 225; A., 1933,799.22 K. Linderstrom-Lang and H. Holter, Comnpt. rend. Trav. Lab. Carlsberg,23 Idem, ibid., 19, (20), 1.24 P. L. Kirk, Mikrochem., 1934,16, 13, 25.1933, 19, (la), 1320 ANALYTICAL CHEMISTRY.and also electrical determinations of copper on similar small weightswere made with the same accuracy.25Apparatus.-Advance in micro-methods depends largely on newdevices and adaptations for small-scale apparatus. The number ofthese is so great that only a few can be mentioned. A variety ofapparatus for micro-qualitative work using a microscope is described,including an apparatus for qualitative electrolysis under the micro-scope whereby0.05yof leadand copper can be separated and detected.26For quantitative electrolysis, a method using a platinum crucible asthe electrode to be weighed is Stirringwith minute bubblesof gas in electrolysis is also described.28 A glass instead of a metalcymene lieating-bath for use in the Pregl carbon-hydrogen deter-mination is claimed to cause less tarring and clogging of the cymeneor decalin.29 A micro-vacuum desiccator adapted from a large-scale type is described.30 A spot plate that can be heated is auseful adjunct to qualitative apparatus.31 A micro-Soxhlet ex-tractor is described ; 32 another simple continuous micro-extractorutilises a sintered-glass filter in place of the usual filter-paper cupand syphon device.33 There is a very large number of designsavailable for micro-heating blocks for melting-point determinationsunder the microscope ; two recent models both use thermometersrather than a thermocouple for temperature measurement, asbeing simpler, and, if calibrated on the instrument, just asaccurate.=, 35 Sublimation is one of the most useful methods ofextraction and purification on the micro-scale; a number of themethods available are discussed and described.36 I n addition tothe micro-burettes already mentioned, a tap-less micro-burette forroutine determinations is described.37 A gauge receiver for use inthe Viebock and Brecher methoxyl determination considerablyfacilitates transference of the liquid to be titrated.38Quantitative Inorganic AmZysis.-No survey of this field is here25 E. Wiesenberger, Mikrochem., 1931-32, 10, 10.26 H. Alber, ibid., 1933-34, 14, 219.2 7 H. Brantner and F. Hecht, ibid., p. 27; A., 1933, 1265.2g H. Lieb, ibid., 1933-34,14, 263; A., 1934, 425.3o W. Munster, ibid., p. 23; A., 1933, 1260.31 E. Frhnkel, ibid., 1933, 13, 179; A., 1933, 801.32 G. Gorbach, ibid., 1932-33, 12, 161.33 A. R. Lowe (Demonstration at Microchemical Club meeting. March 1934).34 L. Kofler, Mikrochem., 1934, 15, 242.36 H. V. A. Briscoe and (Mrs.) J. W. Matthews, Institute of Chemistry36 R. Fischer, Mikrochem., 1934, 15, 247.37 R. Links, ibid., p. 87.3* L. Kahovec, ibid., 1933-34, 14, 341; A., 1934, 790.28 A. OkBE, ibid., 1932-33,12, 205; A., 1933, 140.Publication, 1934, p. 18MATTHEWS. 321attempted, but there have been many developments during thepast year, both in determinations of single elements applied to specialwork, mainly biological, and in complicated separations, involving,in general, the Emich filter-stick method. These complicatedseparations are being applied successfully to a difficult field ofanalytical work, vix., mineral and rock analysis. J. W. M.B. A. ELLIS.J. J. Fox.S. GLASSTONE,J. W. MATTHEWS.REP.-VOL. XXXI.

ISSN:0365-6217    

DOI:10.1039/AR9343100285

出版商:RSC    

年代:1934

数据来源: RSC

摘要:

BIOCHEMISTRY.THE past year has seen notable advances in our knowledge of thcchemical constitution of the sex hormones and of vitamin B,.The more purely chemical aspects of these subjects are dealt with inthe Report on organic chemistry. The identity of vitamin C withascorbic acid has been fully established, and some progress has beenmade in determining the nature of vitamin B,. The mode ofbreakdown of carbohydrate by the enzyme systems of muscle andyeast has been studied further, and evidence has been supplied ingeneral support of the Embden-Meyerhof schemes reported lastyear, as well as in defining more closely certain of the stages involved.Attempts have also been made to link the formation of lactic acidwith other reactions which also take place in muscle.I n amino-acid metabolism a number of somewhat isolated observations havebeen made, and attention is directed in this Report to a renewedinterest in the possibility of carbohydrate formation from fattyacids-a problem which still seems to elude a definite solution.Much valuable work has been done on the nature of the proteolyticenzymes and their substrates, but further clarification is necessarybefore a short review of the situation is possible. During the year,however, the synthesis has been carried out of substituted diketo-piperazines which are claimed to undergo hydrolysis by enzymes-an event of sufficient importance to warrant a special note.Considerable space has been devoted this year to the question ofplant growth-regulating substances, investigations of which aredistributed over a number of years.The establishment of auxinas a definite chemical entity has focused the attention of chemistson these growth substances, and some account of the more biologicalaspects of the subject seems called for. Since the matter has notpreviously been dealt with in this section of the Report, the cus-tomary practice of extending the period under review has beenadopted. The practical agricultural importance of legume inocula-tion also demands reference to the organisms concerned. Interestin the varied and complex problems of the mineral nutrition ofplants and the related subject of metabolism continues to increase.The current year’s work represents a steady general advancementwithout isolated spectacular achievementSTEWART AND POLLARD.323ANIMAL BIOCHEMISTRY.The Secondary Sex Hormones.Interest in the secondary sex hormones continues unabated, andthe elucidation of their chemical structure has made further greatprogress during the year. Improvements in the methods ofseparating the different hormones, and the artificial preparation oftwo of them, justify the hope that the advances in the more purelychemical study of these substances will soon result in similaradvances in our knowledge of their biological effects. The chemicalconstitution of the -secondary sex hormones is considered in detailelsewhere in this volume,l and it will therefore be sufficient heremerely to indicate the suggestions as to structure which are accepteda t present.Testicular Hormone (Androsterone) .-The structure (I) suggestedfor the hormone isolated from male urine and from testes2 hasbeen confirmed by its preparation from epidihydroch~lesterol.~Like cestrone, it is a hydroxy-ketone, but it differs from the ovarianhormone in being saturated, and in retaining the methyl group ofthe sterols at Clo.A noteworthy difference between androsteroneand cestrone is the apparent specificity of the former. As is wellknownY4 a large number of substances, all containing the phen-anthrene ring system but otherwise differing widely from cestrone,possess the power, sometimes in high degree, of inducing cestruswhen injected into immature animals. The formula for andro-sterone allows the theoretical existence of 128 isomerides, of whichRuzicka and his colleagues prepared four.Two of these, derivedfrom dihydrocholesterol and epidihydrocholesterol, differed in thespatial position of the hydroxy-group but agreed in possessing thetrans-configuration of rings A and B ; the other two, from coprosteroland epicoprosterol, had cis-configurations of rings A and B butdiffered similarly with respect to the hydroxy-group. The twocis-compounds were without noticeable effect on comb growthin the capon even in doses 15 times as great as those of natur91androsterone which sufficed to produce a 20% increase in comb area,and only the substance obtained from epidihydrocholesterol had anactivity equal to that of the natural hormone. The specificity,however, is not absolute, and K.Tschernig has actually found athreefold increase in activity to accompany reduction of the keto-group to a secondary alcohol. Moreover, a substance exhibiting3 L. Ruzicka, M. W. Goldberg, J. Meyer, H. Brungger, and E. Eichen-4 Ann. Reports, 1933, 30, 340.P. 206. Ann. Reporte, 1932, 29, 241.berger, Helv. Chim. Acta, 1934, 17, 1395; A., 1221.ti Wien. klin. Woch., 1934, No. 20324 BIOCHEMISTRY.androsterone activity (1 capon or mouse unit in 25-100 x g.)is reported as being obtained by hydrogenation of crude or crystallinef ollicular hormone (oestrone) .Two forms of the hormone are suggested by T. F. Gallagher andF. C. Koch,' one occurring in the testis itself and the other inurine. They find that the hormone obtained from human maleurine is not affected by boiling 3.3% potassium hydroxide solution,whereas hormone prepared from bull testis loses activity in thesecircumstances, and that the loss is not prevented by urine or hormoneprepared from urine.A. A. Adler 8 finds further that in malehuman urine the hormone is present in an inactive form, extractableby butyl alcohol, and activated by boiling with trichloroacetic acid.The Follicular Hormone ((E'drone) .-The accepted structure ofcestrone (11) shows the hormone as differing from androsteronein that ring A is fully aromatic (and has therefore lost the methylgroup at C,,), the 3-hydroxy-group being therefore phenolic insteadof alcoholic.The excretion of estrogenic hormone in male urine has beenconfirmed by B.Zondek? and the isolation and identification of thissubstance with a-folliculin (cestrone) have been accomplished byE. P. Haussler, 10 and by V. Deulofeu and J. Ferrari.11 Zondek 99 l2finds that stallion's urine contains an average of 42,000 mouse unitsof folliculin per litre, but the non-pregnant mare excretes less than500 units per litre. Man and other male animals also excreteceatrogenic hormone, though in much smaller amounts-less than200 units per litre. These findings, in conjunction with the furtherfacts that horse testis yields 54,000 units of follicular hormone perkg., and that implantation of 50 to 100 mg. of testis into spayedinice induces estrus, are taken t o indicate that the testes areconcerned in the formation of oestrone by males.Zondek 12suggests, indeed, that the metabolism of the sex hormones is, in themain, the same for both sexes, and that the male hormone is firstproduced and then converted into the female hormone.6 W. Dirscherl and H. E. Voss, Naturwiss., 1934, 22, 315; A., 815.7 J . Biol. Chenb., 1934, 104, 611; A,, 568.* Nature, 1934, 133, 798; A., 815.xi Helv. Chim. Acta, 1934, 17, 531; A., 702.11 2. physiol. Chem., 1934, 226, 192; A., 1269.L3 Nature, 1934, 133, 494; A., 567.Ibid., p. 209; A , , 332STEWART AND POLLARD. 325The great range of synthetic oestrogenic substances (all containingthe phenanthrene ring system) was discussed last year.4 Theresults of Cook and his collaborators have since been published indetail,13 and another active phenanthrene derivative has beenadded to the list by J.C. Bardhan,l* who distilled 2-carboxy-3 : 4-dihydrophenanthrene-l-propionic acid with acetic anhydrideand obtained an active substance, Cl,HI,O (probably I11 or anisomeride) .CH,A(111.) (IV.) l-Keto-1 : 2 : 3 : 4-tetrahydrophenanthrene.(V.) 9 : 10-Dihydroxy-9 : 10-di-n-butyl-9 : 10-dihydro-1 : 2 : 5 : 6-di-benzanthracene.J. W. Cook, E. C. Dodds, and A. W. Greenwood l5 find that two oftheir synthetic estrogenic substances (IV and V) are devoid ofandrosterone activity, causing no acceleration in comb growthwhen injected into brown Leghorn capons. They bring about analteration in the plumage, however, with development of femalecharacteristics.The increase in the activity of androsterone aftgr reduction of theketo-group is paralleled in the case of cestrone.E. Schwenk andF. Hildebrandt l6 find that reduced cestrone has an activity of30 x lo6 mouse units per g. in the Allen-Doisy test (about threetimes as great as cestrone), and K. David 1' states that the reducedsubstance, cestradiol, has about twice the activity of cestrone.S. L. Cohen and G. F. Marrian l8 report in detail a method forthe separation and colorimetric determination of cestrone andestriol in urine, using a modified Kober reaction l9 (a red colourwithout green fluorescence on boiling with sulphuric and phenol-sulphonic acids, and dilution with water), with analysis of thecolour in a Lovibond tintometer. They state that, although theseparation is not strictly quantitative, the method is sufficiently13 J.W. Cook, E. C. Dodds, C. L. Hewett, and W. Lawson, Proc. Roy. SOC.,14 Nature, 1934, 134, 217; A., 1102.1 5 Proc. Roy. Soc., 1934, By 114, 286; A., 457.16 Naturwiss., 1933, 21, 177; A., 1933, 540.1 7 Actcc Brev. Ne'erl., 1933, 3, 160.18 Biochem. J . , 1934, 28, 1603; A., 1269.1934, B, 114, 272; A., 457.Is Biochem. Z., 1931, 239, 209326 BIOCHEMISTRY.accurate to allow the detection of abnormal amounts of eithersubstance in pregnancy urine.The International Standard of estrogenic activity is definedas that contained in lo-' g. of ketohydroxycestrin (aestrone).The Corpus Luteum Hormone (Luteosterone).-Early in the yearunder review, the pure corpus luteum hormone was isolated,practically simultaneously, by three groups of workers.21, 22y *3, 24There was some difference of opinion a t first as to the exact chemicalcomposition of the hormone, and as to its physical properties, buti t is now agreed that the main active substance is an unsaturateddiketone, C21H3002, melting a t 128".A second active substance,also an unsaturated diketone, melting at 120" and converted intothe first by heat, was considered by Slotta and his collaborators tobe a stereoisomeride of the first. Butenandt at first thought it tobe C21H3202, but now 25 considers the two substances to be chemicallyidentical and to differ only in crystalline form and melting point.Luteosterone thus resembles oestrone in existing in polymorphousmodifications. The close relationship of the corpus luteum hormoneto oestrone, androsterone, and pregnandiol has been shown byA.Butenandt, U. Westphal, andH. Cobler,26 who succeeded in de-~ l - - c ~ o c ~ 3 grading stigmasterol to a substanceH& I I I (probably VI) with physiologicalactivity only slightly inferior to that(VI.) of the natural hormone. The sub-stance originally obtained melted at129-135", but later work 27 gave a pure diketone of melting point129", identical in physical and chemical properties with the naturalhormone, and with the same physiological activity. The pure sub-stance has also been obtained from stigmasterol by E. Fernholz,28and from pregnandiol by A. Butenandt and J. S~hmidt.2~Pure luteosterone has not been known long enough for completeinformation as to its specificity to be obtained, but already anumber of interesting observations have been made, tending to theCH,Ap/VI A//v20 C.Lormand, Bull. SOC. Chim. b i d , 1933, 15, 1566; A., 1934, 457.21 A. Butenandt and U. Westphal, Ber., 1934, 67, [B], 1440; A., 1039.22 A. Butenandt, U. Wostphal, and W. Hohlweg, 2. physiol. Chem., 1934,23 K. H. Slotta, H. Ruschig, and E. Fels, Ber., 1934, 6'7, [B], 1270, 1624;24 M. Hartmann and A. Wettstein, Helv. Chim. Acta, 1934, 17, 878, 1365;25 Ber., 1934, 67, [B], 2055.26 Ibid., p. 1611; A., 1265.28 Ibicl., p. 2027.227, 84; A., 1268.A., 931, 1268.A., 1039.27 Ibid., pp. 1903, 2085.29 Ibid., p. 1901STEWART AND POLLARD. 327conclusion that it is at least much more specific than oestrone.Acurious fact is that reduction of the keto-group attached to thepentamethylene ring reduces the activity very markedly %-aneffect the opposite of that found with cestrone and androsterone.Equally, reduction a t C, to the 3-hydroxy-ketone (actually thesubstance from which the synthetic hormone is obtained by dehydro-genation) gives an inactive 28 and cholestane,28though it resembles luteosterone spectroscopically, is withoutphysiological activity. The dihydroxy-compound correspondingto luteosterone is, of course, pregnandiol, which is physiologicallyinactive. Luteosterone thus differs markedly from the other knownsex hormones in that the keto-groups seem t o be essential to itsactivity.Origin of the Sex Hormones.-The fact that in all three hormones,the configuration of rings B, C, and I, is that of cholesterol and thebile acids is significant evidence that in the animal body they ariseby degradation of cholesterol.The relationship between preg-nandiol and luteosterone suggests that the former (which could bederived from cholesterol through lithocholic acid) may be theprecursor of the corpus luteum hormone in vivo. Pregnandiolcannot, however, be the natural precursor of androsterone, for it is amember of the coprostane series, whereas the testicular hormoneis derived from epidihydrocholesterol. Ruzicka has suggestedthat androsterone arises in nature by a process similar to t,hat bywhich it is obtained in vitro-epimerisation of the hydroxy-groupof dihydrocholesterol, followed by oxidation of the side chain.J.W. however, points out that an unsatdrated hydroxy-ketone recently isolated from urine by A. Butenandt 32 may, if thesuggested position of the double bond is correct, be the trueprecursor. The substance can, in vitro, be hydrogenated to andro-sterone .Little can yet be said of the origin of oestrone, since thestereochemical relations of its ring system are not known, butreference has already been made to Zondek’s suggestion that it isderived from androsterone by a, process of dehydrogenation anddemet hylation.Vitamin B,.Although there is not yet absolute agreement as t o the identityof the various crystalline vitamin B, preparations obtained bydifferent workers, it seems probable that they all contain the samesubstance but differ in purity.A. G. Van Veen 33 reports a crystal-30 A. Butenandt arid J. Schmidt, Ber., 1934,67, [B], 2092.31 Nature, 1934, 134, 758.33 Nature, 1934, 133, 137; A., 333.Wien. klin. TVoch., 1934, 47, 936328 BIOCHElldISTRY .line preparation of oryzanin (from rice polishings) which has acurvative action on polyneuritic rice- birds corresponding to 500international standard units per mg., an activity which he claimsto be greater t,han that of torulin from bakers' yeast. He describesthe substance as containing sulphur, with C 40.7% and H 5.5%.On the other hand, H. W. Kinnersley, J. R. O'Brien, and R. A.Peters point out that an equal activity has been attained in someof their preparations, but that torulin crystals contain 42.2% C,a difference which they regard as significant.As they state thatmost vitamin B, crystals contain inactive material, it follows thatsmall differences in activity by no means necessarily point to completenon-identity of different preparations. Indeed, crystallographicmeasurements by J. D. Bernal and (Miss) D. Crowfoot 35 suggestthat the different groups of workers are actually dealing with thesame substance, for they find that crystals from several differentsources are substantially identical in form and X-ray pattern.They consider that their measurements suggest a conjugated ringstructure, with the heavy atoms, sulphur and chlorine, not both atthe ends of the molecule.A similar identity of the various crystalline preparations ofvitamin B, is suggested by the most recent work of F.F. Heyrothand J. R. Loofbourow,36 who find very similar absorption spectrawith a number of samples obtained from different laboratories.They state that there is marked correlation between vitaminactivity and absorption a t or near 2600 8. The absorption curves,with maxima a t 2650 and 2350 pi., resemble those of cytosine, andit is therefore suggested that the vitamin molecule contains apyrimidine of the cytosine type. The discrepancy between theseresults and the earlier ones of R. A. Peters and J. St. L. P h i l p ~ t , ~ 'which gave the characteristic absorption maximum at 2450 8., isexplained as probably due to the different solvents used.by oxidising vitaminB, with nitric acid, have obtained two substances, each containingfive carbon atoms.The first of these was isolated as an ethyl esternitrate, C,H,,05N3, the free acid being, therefore, C5H,0aN,. Itwas not identical with any of the four possible glyoxaline acids ofthis formula, and it was suggested that it might be a dioxymethyl-pyrimidine. The second substance, C,H,O,NS, gives a methylester, loses ammonia and hydrogen sulphide when warmed withA. Windaus, T. Tschesche, and R.34 Nature, 1934, 133, 177; A., 333.Ibid., 1933, 131, 911; A., 1933, 768.38 Ibid., 1934, 134, 461; A,, 1270.37 Proc. Roy. SOC., 1933, B, 113, 48; A,, 1933, 645.3* 2. physiol. Chem., 1934, 228, 27STEWART AND POLLARD. 329alliali, and gives the zinc dust-pine splinter reaction which is heldto indicate the presence of a pyrrole ring.The formula (VII) wastentatively suggested for this substance, but the suggestion hassince been disproved by K. N i e ~ s e r , ~ ~ who synthesised a substance offormula (VII). He suggests that the compound isolated by Windausmay be represented by one or other of the formulae (VIII) and (IX),of which the latter is the more probable. The complete identifi-cation of these two substances, which account for ten of the twelvecarbon atoms of vitamin B,, will form an important step in deter-mining the constitution of the vitamin.H 2 v - p HO,C$-RH H$-G* C0,HS:Cvc'Co2H NH Hs*cxcH HSmcvCH NH(IXJ (VII.) (VIII.)Vitamin B,.Last year it was reported that the flavins, yellow water-solubledyes extracted from both 'animal and vegetable sources, possessedintense vitamin B, activity,and that lactoflavin from wheywas claimed by Kuhn et al.40 HTw'\f'ycHsthe vitamin. The elucidation ofCO N CHto be probably identical withthe constitution of the flavinshas proceeded so rapidlythat, asis described in more detail else-where,41 they are now known H8 9 - v y C H 2 * O HOH OHto be derivatives of alloxazine, and a substance of constitutionrepresented by formula (X) has been synthesised and stated to beidentical with la~toflavin.~~Flavins have been obtained, though not always in pure crystallineform, from a number of new sources. K. G. Stern has describedthe isolation of hepatoflavin from horse liver, and has shown thaton irradiation it gives products identical in absorption spectra withthose from other flavins, and P.Karrer et aLM give a detailedaccount of their preparation of hepaflavin, which is identical withlactoflavin in elementary composition, melting point, crystallineform, and absorption spectra. W. Koschara 45 has described39 Ber., 1934, 67, [ B ] , 2080.40 R. Kuhn, H. Rudy, and T. Wagner-Jauregg, Ber., 1933, 66, [B], 1950;A , , 1934, 227.4 1 P. 263.43 Nature, 1933, 132, 784; A., 1934, 97.44 Helv. Chim. Actu, 1934, 17, 419; A., 538.4a R. Kuhn and F. Weygand, Ber., 1934, 67, [B], 2084.46 Ber., 1934, 67, [BJ, 761.L 330 BIOCHEMISTRY.uroflavin, from urine, as differing from lactoflavin in elementarycomposition, containing CH,O extra, and in melting point (thoughit does not depress the melting point of lactoflavin), but indis-tinguishable from it by chromatographic examination.B. C. Guhaand H. G. Biswas46 have obtained renoflavin from ox kidney.F. Plant and K. Bossert 47 have found a chloroform-soluble pigmentresembling lumiflavin in the serum and cerebro-spinal fluid of manand rabbit.The identity or, alternatively, the exact differences, of thesevarious flavins are still undecided. P. Karrer and K. Schopp4*find the flavins of malt, milk, egg, liver, and dandelion to be identicalin crystalline form and melting point, whereas Koschara hasdescribed uroflavin as non-identical with laotoflavin. It has beensuggested 4g that the results of elementary analysis a t presentindicate non-identity, but the existence of a group of closely relatedsubstances, alloxazines substituted in the 9-position.This questionof the identity of the flavins bears importantly upon the furtherquestion of the nature of vitamin B2-whether the vitamin is asingle naturally occurring flavin, whether, as in the estrogenichormone, the activity associated with the vitamin is a property ofmany substances possessing a common grouping, or whether, asin the case of carotene, the substances isolated are vitamin pre-cursors. This problem cannot yet be regarded as definitely solved,though there is no doubt as to the relationship of the pigments tovitamin B, activity. The flavin content of various tissues parallelsthe vitamin B, activity ; 50 lactoflavin retains its activity afterrepeated and varied purifications ; 61 (a) and tetra-acetyl lactoflavinalso shows activity 52 and retains this activity on regeneration ofthe original flavin by hydr~lysis.~l ( b ) But even more impressive isthe fact that the synthetic lactoflavin, in doses of 15 mg. per day,produces a growth of 9-10 grams per week in &-gram rats fed on adiet deficient in vitamin B,.53 One may reasonably incline to the4 6 Current Sci., 1934, 2, 474; A,, 1041.47 Klin.Woch., 1934, 13, 450; A., 1022.48 Helv. Chim. Acta, 1934, 17, 1013; A., 1233.40 K. G. Stern and E. R. Holiday, Ber., 1934, 67, [B], 1442; A., 1041.5O E. Adler and H. von Euler, Svensk Kem. Tidskr., 1933, 45, 276; A.,1934, 226; H.von Euler and E. Adler, 2. physiol. Chem., 1933, 223, 105;A., 1934, 544.5 1 (a) R. Kuhn, H. Rudy, and T. Wagner-Jauregg, Zoc. cit.(b) R. Kuhn and T. Wagner-Jauregg, Ber., 1933, 66, [B], 1577; A.,82 P. Gyorgy, R. Kuhn, and T. Wagner-Jauregg, 2. physiol. Chem., 1934,53 R. Kuhn and F. Weygand, bc. Cit.1933, 1320.223, 241 ; A., 706STEWART AND POLLARD. 331view that lactoflavin (or a lactoflavin-protein compound) is itselfvitamin B, on account of the specificity shown. Both the aromaticmethyl groups and the side chain attached to the 9-position of thealloxazine ring are necessary for activity, but as yet completeinformation as to the degree of specificity in the side chain is lacking.A compound with n-amyl in place of the E-arabinose of lactoflavinhas been synthesised, but no report of its biological activity has yetcome to the Reporter’s notice.54 Lactoflavin combines with protein,and according to P.Gyorgy, R. Kuhn, and T. Wagner-Ja~regg,~~it exists largely in that form in liver and yeast. The proteincompound retains vitamin B, activity.56The yellow oxidation enzyme of 0. Warburg and W. Christian 57consists of flavin combined with protein. The reduced leuco-formof the enzyme gives the coloured form and hydrogen peroxide whenshaken with atmospheric oxygen ; anaerobically it reduces methyl-ene-blue and re-forms the yellow enzyme.58 H. Theorell 59 findsthat the crystalline enzyme, dialysed against dilute hydrochloricacid, is split into two inactive components, pigment and protein.By mixing electrolyte-free solutions of these components, heobtains restoration of enzyme activity.Kuhn ,53 indeed, believesthat the biological activity of lactoflavin consists in its assumptionof enzymic properties by combination with protein.One of the biological tests for vitamin B, depends on its power ofpreventing pellagra or pellagra-like dermatitis, and this power isnot-possessed by flavins. This naturally raises the question of theidentity of vitamin B, in spite of the close correspondence betweenthe vitamin and flavin by the growth test. C. A. Elvehjem andC. J. Koehn 60 simply deny the identity of the flavins with vitaminB,, on the ground that colourless liver preparations, after removalof flaviiis, were highly active in preventing pellagra.They wish,in fact, to retain the name B, for the still unknown anti-pellagrafactor and to find another term for the activity shown by theflavins. P. GyorgyY6l on the other hand, considers that the oldvitamin B,, the anti-dermatitis factor, consists of the real B, (flavin),and a factor, B,, responsible for the prevention of the pellagra-likedermatitis of rats. He finds that B, is not identical with any ofthe water-soluble vitamins hitherto described. The difference54 R. Kuhn and F. Weygand, Ber., 1934, 67, [B], 1939.5 5 2. phyaiol. Chem., 1933, 223, 241; A., 1934, 706.56 R. Kuhn and G. Moruzzi, Ber., 1934, 67, [ B ] , 1220; A., 932.57 Ann. RepoTt8, 1933, 30, 159.58 0. Warburg and W. Christian, Biochem. Z., 1933, 266, 377; A,, 1933,59 Ibid., 1934, 272, 155; A., 1136.60 Nature, 1934, 134, 1007.979.61 Ibid., 1934, 133, 498; A., 560332 BIOCHEMISTRY.between the two workers is obviously one of nomenclature alone,but, the existence of a separate factor having been independentlyobserved, only confusion can result from the multiplication ofnames.It seems reasonable, in view of the general acceptanceaccorded to the identification of lactoflavin with vitamin B,, t oadopt the suggestion of Gyorgy, and to apply the term B, to theassociated anti-pellagric substance until it, in its turn, has beenidentified chemically.It has been suggested on several occasions that vitamin B, is anactive factor in the liver preparations used for the treatment ofpernicious anaemia, and there is no doubt that such preparationsare rich in vitamin B, or that, conversely, vitamin B concentratesmay possess definite curative value in pernicious anaemia.It isworth recording, therefore, that yeast extracts have recently beenprepared which-possess high curative value but little or no vitaminB, .61aVitamin C.The year 1933 produced very strong evidence that vitamin Cis identical with ascorbic acid, but complete acceptance had toawait the biological investigation of the synthetic material whichhad just been obtained by Haworth and his collaborators.62 Com-parative tests on guinea pigs of synthetic Z-ascorbic acid andhighly purified natural material have now demonstrated the com-plete identity of the substances in physiological as well as in physicaland chemical proper tie^.^^ Further accounts of the synthesis ofascorbic acid have been published by the Birminghamand other syntheses by T.Reichstein and A. Grussner 65 and byF. Micheel, K. Kraft, and W. Lohmann 66 confirm the claim thatthe synthetic substance is physiologically identical with the naturalvitamin C.It thus appears that 2-ascorbic acid is, without doubt, vitaminC ; but other closely related compounds, which, however, havenot yet been found to occur in nature, seem to possess someantiscorbutic activity along with a resemblance to ascorbic acidin readily undergoing reversible oxidation. For instance, K.Maurer and B. Schiedta' obtained a substance which theyC. C. Ungley and G. V. James, Quart. J .Med., 1934, 8 (new series), 523.62 Ann. Reports, 1933, 30, 336.1x3 W. N. Haworth, E. L. Hirst, and S. S. Zilva, J., 1934, 1155; A., 1091;V. Demole, Biochem. J . , 1934, 28, 770; A., 934.64 J . , 1934, 62, 1192; A., 279, 1091.65 Helv. Chim. Acta, 1934, 17, 331; A , , 510.86 2. physiol. Chem.., 1934, 225, 13; A., 869.6 7 Rer., 1933, 66, [B], 1054; A.. 1933, 936STEWART AND POLLARD. 333later6* identified as d-arabo-ascorbic acid and showed to haveabout &th of the antiscorbutic activity of the vitamin itself.The occurrence of toxic symptoms following the administrationof excessive amounts of vitamin D has naturally directed attentionto the possibility of hypervitaminosis in other cases. G. Gothlin 69finds that a t least 1-33 mg. of crystalline ascorbic acid are requireddaily to protect guinea pigs completely against pre-scorbutic changesin the molar teeth, and calculates the minimum daily dose for adultmen of 60 kg.at 19-27 mg. (3-16-4.5 mg. per kg.). These figuresare rather higher than those previously reported for the protectionof guinea pigs 7O (06---1*0 mg. per day), but the test used is morerigorous. On this basis the doses which E. KramQr 71 found to bewell tolerated by infants (15-50 mg.) cannot be considered excessive,but V. Demole 72 found no ill effects to follow the administrationto guinea pigs of amounts up to 2.5 g. per kg. of body weight forsix days.The mode of action of vitamin C is still by no means clear, thoughthe availability of the pure substance will undoubtedly facilitatethe attack on this problem.The tendency is naturally to examineascorbic acid with reference to various enzyme systems andespecially oxidising systems in view of the ease with which it under-goes reversible oxidation. J. H. Quastel and A. H. M. Wheatley 73find that slices of rat liver or of scorbutic guinea pig liver (but notalways of normal guinea pig liver), suspended in glycerophosphate-Locke solution containing sodium butyrate or crotonate, give anincreased production of acetoacetic acid and an increased oxygenusage when ascorbic acid is added. Further, they find that ascorbicacid prolongs the steady uptake of oxygen by liver slices. Theoxidation of fatty acids by liver slices is largely inhibited by iodo-acetic acid, and this inhibition is partly neutralised by ascorbic acid,although there is no evidence of a chemical reaction between thevitamin and iodoacetic acid analogous to that between the lattcrand glutathione.Quastel and Wheatley suggest that ascorbic acidplays some part in maintaining the general respiratory metabolism,on the integrity of which the oxidation of fatty acids (and, presum-ably, of other substrates) must ultimately depend. Ascorbic acidhas also been described as having an activating effect on proteases of68 Ber., 1934, 67, [B], 1239; 0. Dalmer and T. Moll, 2. physiol. Chem.,69 Nature, 1934, 134, 569; A., 1271.7 1 Deut. med. Woch., 1933, 59, 1428; A., 1934, 1271.72 Biochem. J . , 1934, 28, 770; A , , 934.73 Ibid., p. 1014; A,, 934; cf.D. C. Harrison, ibid., 1933, 27, 1601; A.,1933, 222, 116; A., 1934, 227.'O Ann. Reports, 1932, 29, 253.1933, 1340334 BIOCHEMISTRY.the cathepsin type 74 (from which the natural activators had beenremoved by acetone), increased by Fe", Fe"', and Cat.*, as well as onarginase 75 in presence of Fe" and Fe"' (dehydroascorbic acid actssimilarly on arginase). On the other hand, wheat amylase andcatalase are said to be inhibited by ascorbic as is tyrosinasewith respect to tyrosine, 3 : 4-dihydroxyphenylalanine, and dl-adrenaline. 76The Breakdown of Carbohydrate to Lactic Acid in Muscle.The important Embden-Meyerhof theory of the chemical changesinvolved in the conversion of carbohydrate into lactic acid bymuscle or into ethyl alcohol by yeast was reviewed in some detaillast year.77 Since that time, a considerable volume of evidence hasappeared in support of the theory, although there are indicationsthat the series of reactions proposed for the formation of lacticacid in muscle may not represent all the changes taking place.The crux of the matter is, of course, the position of methylglyoxal,which Meyerhof ignores as an unimportant by-product (or possibly,78when it is isolated, an artefact) from triose-phosphoric acid.Thisview, however, is difficult to reconcile with a number of experi-mental observations, and a dual or multiple route has been suggestedby several workers.79$ 85The isolation of methylglyoxal from muscle pulp has frequentlybeen reported, and, especially when the glyoxalase system has beeninhibited (by anti-glyoxalase, or by iodoacetic acid), the amountproduced represents a considerable fraction of the added substrate(hexose-diphosphoric acid or glycogen).Claims of this naturehave recently been renewed by N. Arayama,80 who reviews the earlierpapers on the subject. Dealing with lactic acid fermentation byyeast, E. Auhagen and T. Auhagenal confirm the production ofmethylglyoxal and state that it is a primary product of the reactionand is not an artefact due to the addition of " fixing " reagent(2 : 4-dinitrophenylhydrazine). Also using yeast, M. Kobe1 andH. Collatz 82 find that, under conditions shown to be optimal forthe production of met hylglyoxal from hexose-diphosphoric acid,7 4 H.von Euler, P. Karrer, and F. Zehender, Helv. China. Acta, 1934,7 5 P. Karrer and F. Zehender, ibid., p. 737; A., 1034.7 6 E . Abderhalden, Perrnentforsch., 1934,14, 367; A,, 1138.7 7 Ann. Reports, 1933, 30, 327.7 8 Ann. Inst. Pasteur, 1934, 53, 221; A., 1137.7 9 M . Jowett and J. H. Quastel, Biochem. J., 1934, 28, 162.80 J . Biochem. Japan, 1934, 20, 371; see also, E. Aubel and E. Simon,81 Biochem. Z., 1934, 268, 247 ; A., 662.17, 157; A., 461 (cf. A., 1933, 873).Compt. rend. Soc. Biol., 1933, 114, 905; A., 1934, 807.82 Ibid., p. 202 ; A., 449STEWART AND POLLARD. 335only lactic acid is formed from added glyceraldehyde-phosphoricacid. T+ey conclude that methylglyoxal is formed from sugars,but not from this particular triose-phosphoric acid-a conclusiondefinitely suggestive of a dual route.One of the strongest arguments in favour of the non-participationof methylglyoxal in lactic acid formation is the finding that dialysedmuscle extracts, which contain no glutathione (co-enzyme ofglyoxalase), still produce lactic acid on addition of a magnesiumsalt and adenylic acid pyrophosphate.This argument still holds,at least as showing that methylglyoxal is not an obligate inter-mediate, The fact that glutathione is destroyed in viko by iodo-acetic acid, which also inhibits lactic acid production, meets theclaim that iodoacetic acid acts in other ways 83 than by preventingglyoxalase activity. This claim is supported by certain facts to bereported later, and by the observation that glycolysis in shed bloodis inhibited by iodoethyl alcohol, which, however, does not formhydriodic acid with glutathione in vitro.84 Nor is it overthrown bythe fact that added glutathione can prevent iodoacetate poisoningin the isolated frog’s ventricle and can even cause recovery from thepoisoning when the ventricle has almost ceased to respond tostimulation.85R. Caddie and C. P. Stewart 85 have advanced evidence whichsupports the Embden-Meyerhof scheme of lactic acid production,but which again is suggestive of a dual route. Using the isolatedfrog’s ventricle, exhausted of available carbohydrate in an atmo-sphere of nitrogen, they found (confirming N. Freund and W.Konig,86 and their own earlier work with A. J. Clark 87) that thepower of contracting on stimulation was entirely restored by glucose.Incidentally, it was also restored by mannose, but not by galactose,fructose, or by any pentose or disaccharide.It was a reasonableassumption that intermediates in the conversion of glucose intolactic acid should also restore the power of responding to stimu-lation, and actually a partial restoration was obtained by additionto the perfusion fluid of sodium pyruvate with sodium glycero-phosphate, though neither substance was effective alone. On theother hand, a partial, but rather better restoration was given bymethylglyoxal : this at least shows that, however methylglyoxalis formed, the energy of its conversion into lactic acid is utilisableby the contractile processes. I n both cases the partial recovery83 Ann.Reports, 1933, 30, 330.84 D. M. Mowat and C. P. Stewart, Biochem. J., 1934, 28, 774; A., 912.85 R. Gaddie and C. P. Stewart, J. Physiol., 1934, 80, 457.88 Arch. exp. Path. Pharm., 1927, 129, 193.87 J . Physiol., 1932, 75, 321336 BIOCHEMISTRY.became full recovery on further addition of glucose. While, then,no evidence suggests that the chain of reactions required by theEmbden-Meyerhof scheme does not take place, there is definiteevidence that other reactions, also leading to lactic acid production,may occur simultaneously-or perhaps under slightly differentconditions.The first stage in the conversion- of fructose-diphosphoric acidinto lactic acid is the splitting of the six-carbon chain with theproduction of two molecules of triose-phosphoric acid.It hasalready been shown 88 that one component of the synthetic (racemic)glyceraldehyde-phosphoric acid is capable of conversion by muscleextracts into phosphoglyceric and glycerophosphoric acids-thesecond stage in lactic acid formation-or, under different conditions,into pyruvic and glycerophosphoric acids-the third stage. Earlythis year, 0. Meyerhof and K. Lohmanns9 found that hexose-diphosphate, added in low concentration to co-enzyme-free musclejuice or yeast maceration juice, was rapidly converted into a triose-phosphoric acid (in yields up to 60%) which closely resembled, butwas not identical with, synthetic glyceraldehyde-phosphoric acid.They suggested that it was slightly impure dihydroxyacetone-phosphoric acid, and later found that it was indeed identical withthe synthetic substance, which was prepared by W.Kiessling 91and found by him to be fermentable. This ester is readily hydrolysedby 0*5N-sodium hydroxide to lactic and phosphoric acids, and byacid to methylglyoxal and phosphoric acid. Meyerhof and Lohmannfound that, whether they used hexose-diphosphoric acid or thesynthetic dihydroxyacetone-phosphoric acid as substrate, therewas, in the presence of enzyme, the same ultimate equilibriumbetween the two esters, and it was possible to prepare hexose-diphosphoric acid from the triose ester. The effect of temperatureon the equilibrium was the same whether the initial substrate wasnatural or synthetic dihydroxyacetone-phosphoric acid or hexose-phosphoric acid.The equilibrium was disturbed by potassiumcyanide and by sodium bisulphite, the presence of the latter allowingthe isolation of dihydroxyacetone-phosphoric acid (from hexose-diphosphoric acid) in 90% yield. The enzyme concerned in thisreaction (zymohexase) is water-soluble, moderately thermo-stable,and is unaffected by iodoacetate, fluoride, or o ~ a l a t e . ~ ~ A point ofconsiderable interest is that the conversion of hexose-diphosphoricacid into two molecules of dihydroxyacetone-phosphoric acid is88 Ann. Reports, 1933, 30, 329.89 Naturwiss., 1934, 22, 134; A., 660. Ibid., p. 220; A., 807.B2 0. Meyerhof and K. Lohmann, Biochem. Z., 1934, 871, 89; A., 927.Ber., 1934, 67, [B], 868; A., 764STEWART AND POLLARD.337an endothermic reaction, the measured heat of reaction being givenas - 33.5 g.-cals. per gram,93 or - 6000 g.-cals. per gram-molecule,Q4of the hexose-diphosphoric acid.It has thus been shown that both the triose-phosphoric acids tobe expected from hexose-diphosphoric acid are capable of yieldinglactic acid in the presence of muscle extracts, and of doing so by wayof the intermediates suggested by Embden and his colleagues. Thework of Meyerhof and Lohmann suggests that dihydroxyacetone-phosphoric acid is the main triose ester to be formed in vivo, and inits case its production from and conversion into hexose-diphosphoricacid have also been demonstrated. This does not yet appear tohave been done for glyceraldehyde-phosphoric acid, though it hasbeen shown that glyceraldehyde is capable of yielding glycogen inthe animal body.95The breakdown of phosphoglyceric acid to pyruvic acid has beenfurther studied.The enzymic breakdown occurs only in thepresence of adenylic acid pyrophosphate and a, magnesium salt,96and in the absence of these a phosphopyruvic acid is obtained whichexists in enzymic equilibrium with phosphoglyceric acid, and whichis hydrolysed by muscle extract containing co-enzyme to pyruvicand phosphoric acids. The degradation of Z-phosphoglyceric acidto pyruvic acid by fresh bottom yeast has been confirmed byW. Schuchardt and A. Vercell~ni,~~ and C. Neuberg and M. Kobe1 98have observed a similar reaction in the presence of pulped germinatedpeas and beans.A. E. Braunstein has observed it also in thepresence of haemolysed (but not intact) erythrocytes from rabbitsand pigeons. It is evident, therefore, that the responsible enzymeis widely distributed, a fact which lends further support to thesupposition that the conversion of phosphoglyceric acid intopyruvic acid is a general step in carbohydrate breakdown.The simple view that the enzymic hydrolysis of phosphagen tocreatine and phosphoric acid provides the energy for muscularcontraction, and that the resynthesis of phosphagen is a recoveryprocess at the expense of carbohydrate breakdown, is becoming lesssatisfactory as a result of recent work. E. Lundsgaard 99 finds thatin muscle poisoned by iodoacetic acid the energy utilisation isgreater than can be accounted for by the phosphagen breakdown,and a similar conclusion can be reached from figures given for93 0.Meyerhof and K. Lohmann, Naturwiss., 1934, 22, 462 ; A., 1034.D4 Idem, Biochem. Z., 1934, 273, 73; A., 1261.95 R. Stoher, 2. physiol. Chem., 1934, 224, 229; A., 919.96 K. Lohmann and 0. Meyerhof, Biochem. Z . , 1934,273, 60; A., 1261.9 7 Ibid., 1934, 272, 434; A., 1260. Ibid., p. 457; A., 1260.99 Ibid., 1934, 269, 308; A., 685338 BIOCHEMISTRY.anaerobic cardiac muscle by A. J. Clark, M. G. Eggleton, andP. Egg1eton.l Lundsgaard considers that the extra energy cannotbe accounted for by utilisation of adenylic acid pyrophosphate,since this only becomes perceptible a t a late stage after considerablefatigue, and he failed to find anaerobic synthesis of phosphagen orhydrolysis of adenylic acid pyrophosphate.He considers, in fact,that phosphagen breakdown is a recovery process.One may note here that hitherto no chemical reaction has beendiscovered which can a t present be regarded as initiating muscularcontraction ; first, lactic acid formation was shown to be a recoveryprocess, and now phosphagen hydrolysis is placed in the samecategory. It seems that more attention might well be given to theviews of Ritchie,2 who suggests that the contractile processes ofmuscle are physical (he regards the contracted as the true restingstate of muscle, and the relaxed as the condition in which tension isbeing maintained, thus reversing the usual notion), and that all theknown chemical reactions are recovery processes.A similar conception of phosphagen hydrolysis as a secondaryreaction is instinct in the suggestion of K.L~hmann,~ who considersthat the production of creatine and phosphoric acid from phosphagenis not due to a specific phosphatase, but is the resultant of tworeactions :Adenylic acid pyrophosphate = adenylic acid + 2H,P04.Adenylic acid + 2 phosphagen = adenylic acid pyrophosphate +creatine.In accordance with this view he finds 4 that, though adenylic acidand phosphagen separately are inactive as co-enzyme of lactic acidformation, a mixture of the two exhibits the activity of adenylicacid pyrophosphate. J. K. Parnas and P. Ostern accept Loh-mann’s view of the connexion between adenylic acid pyrophosphateand phosphagen breakdown, but go further, considering the break-down of carbohydrate also to be coupled with these reactions and tobring about the resynthesis of phosphagen :(1) Adenylic acid pyrophosphate + glycogen + water = adenylicacid + fructose diphosphoric acid.(2) Adenylic acid + phosphocreatine = adenylic acid pyrophos-phate + creatine.(3) Creatine + fructose diphosphoric acid = phosphocreatine +lactic acid.Recently, the same authors with T.Mann have adduced evidence1 J. Physiol., 1932, 75, 332.3 Biochern. Z., 1934, 271, 264; A., 1034. Ibid., p. 278; A., 1033.Nature, 1934, 134, 627.Ibid., 1933, 78, 322.Ibid., p. 1007STEWART AND POLLARD. 339that the resynthesis of phosphagen is particularly associated withthe conversion of phosphoglyceric acid into pyruvic acid.Phospho-glyceric acid, added to muscle pulp poisoned with iodoacetic acid,prevents ammonia formation which occurs in presence of freeadenylic acid but not of the pyrophosphate, and also allows theformation of phosphagen. Resynthesis of phosphagen in thesecircumstances is not permitted by addition of free phosphate or ofany of the other intermediates in the Embden-Meyerhof series.Moreover, addition of pyruvic acid and phosphate together tofluoride-poisoned muscle pulp stops ammonia formation andallows synthesis of adenylic acid pyrophosphate (and therefore,according to Lohmann, of phosphagen). It is suggested, therefore,that the real intermediary phosphate carrier is phosphopyruvicacid, and that the phosphate from this substance is transferred tocreatine and thence to adenylic acid.Reaction (3) above thusincludes, as one of its stages, the reaction :Phosphoglyceric acid + creatine (= phosphopyruvic acid +creatine + H,O) = pyruvic acid + phosphocreatine + H,O.Parnas and his colleagues point out that their experimentsindicate an inhibitory effect of iodoacetic acid on the earlier stagesof carbohydrate breakdown, i.e., on some reaction prior to theformation of phosphoglyceric acid. Meyerhof and Lohmann 92have found that iodoacetic acid does not interfere with the formationof triosephosphoric acid from hexose-diphosphoric acid. It followsthat iodoacetic acid inhibits either the formation of hexose-di-phosphoric acid or the conversion of dihydroxyacetone-phosphoricacid into glycerophosphoric and phosphoglyceric acids.SinceParnas and Ostern (Zoc. cit.) have found that in the iodoacetic acidpoisoned heart adenylic acid accumulates with formation, not offree phosphate, but of carbohydrate phosphoric esters, it seems thatiodoacetic acid must act in the latter of these reactions.There are, of course, difficulties in the complete acceptance ofthe suggestions of Parnas, though possibly they may be removedwhen a more detailed exposition appears. In particular it is noteasy to reconcile Parnas's series of reactions with the long con-tinuance of muscular contraction after poisoning with iodoaceticacid. Aerobically, cardiac muscle, poisoned with iodoacetate, cancontinue to contract for some hours without lactic acid formationand with maintenance of the usual phosphagen concentration.'It would appear, therefore, that phosphagen can be resynthesised a tthe expense of ot her-presumably exot hermic-reactions thanlactic acid formation, and that, although the phosphate trans-7 A.J. Clark et aZ., Zoc. cit340 BIOCHEMISTRY.ference postulated by Parnas may occur normally, it is not essentialto the process of contraction. This verdict is probably justified inspite of the admitted differences between cardiac and skeletal muscle(though it is doubtful whether any of them are really fundamental).To the number of these differences, one more has recently beenadded. F. Beattie, T. H. Milroy, and R. W. M. Strain8 haveobtained, from the heart of the rabbit, cat, dog, ox, and horse, asubstance which, on the basis of chemical composition and behaviourtowards acid, they describe as different from the adenylic acidpyrophoshate of skeletal muscle, and as resembling a dinucleotidecomposed of one molecule of adenosine-diphosphoric acid and onemolecule of adenosine-triphosphoric acid.Only about 60% of itstotal phosphorus is labile (as compared with 67% in the case of thesubstance from skeletal muscle), and it is stated to be more powerfulthan the ordinary adenylic acid pyrophosphate in reactivatinginactive extracts of both voluntary and cardiac muscle. The samesubstance has apparently been obtained from fresh heart by P.O ~ t e r n , ~ who described the isolation of a diadenosine-pentaphosphoricacid, but failed to obtain it from pig heart, which yielded adenosine-5-phosphoric acid instead.The Metabolism of Amino-acids.Cystine and Methionine.-H. S.Loring, D. Dorfmann, and V. duVigneaud 10 have confirmed the observation that d-cystine does notpromote growth, but find that mesocystine can be used as the Bolesource of cystine. They suggest that this is due t o reduction withliberation of Z-cysteine. Corresponding to this difference in growth-promoting power, the cystine isomerides show differences in the easewith which they are oxidised in the animal body.ll When thelaevo-acid is fed to rabbits, about 80% of the extra urinary sulphuris in the form of sulphate, but with the dextro-acid only about 45%.Racemic and mesocystine give intermediate results.Similarresults have recently been reported by J. A. Stekol,12 who findsthat dogs excrete as sulphate 40% of the sulphur from dZ-cystinebut only 12% of that from Z-cystine. V. du Vigneaud, H. S. Loring,and H. A. Craft l3 find that homocystine, dl-methionine, and S-methylcystine are all readily oxidised by rats, the percentage of theextra urinary sulphur appearing as sulphate being practically the8 Biochem. J., 1934, 28, 84, 90; A., 431.9 Biochem. Z., 1934, 270, 1 ; A., 677.10 J . Biol. Chern., 1933, 103, 399; A., 1934, 212.11 V. du Vigneaud, H. A. Craft, and H. S. Loring, ibid., 1934, 104, 81 ; A.,12 Ibid., 1934, 107, 225.322.l3 Ibid., 1934, 106, 481; A., 921STEWART AND POLLARD.341same for the first two. 8-Methylcystine, however, does notstimulate growth.The ready oxidation of dl-methionine has been confirmed 14, l6and the fact that a-benzoylmethionine is not attacked by the animalbody is reported by R. W. Virtue and H. B. Lewis,15 who suggestthat methionine is demethylated to homocysteine. These authorsalso find that the urinary substance (after methionine feeding)giving the cyanide-nitroprusside test 16 does not respond to theSullivan test for cystine.N. W.'Pirie 17 has begun a study of the intermediate stages in theoxidation of sulphur-containing amino-acids, having succeeded indemonstrating their oxidation to sulphate by slices of rat liver andkidney. He finds that cystine is oxidised only after reduction tocysteine ; glutathione only after hydrolysis ; methionine is oxidisedrather slowly, and during the oxidation the fluid contains a substancewhich gives the nitroprusside reaction ; ethylcysteine is oxidisedslowly and, curiously, ergothionine not a t all.Pirie suggests,therefore, that in all cases oxidation starts from a sulphydryl com-pound the formation of which by reduction or dealkylation is thefirst stage. He suggests, tentatively, the following series of reactions,of which the third has already been shown to proceed spontaneouslyat body p H :R*S*S*R +- 2R*SH -+ 2R*S*OH -+ R*S02H -+ H2S03 -+ H2S04or \2R*S*CH3 L k R~SHV. du Vigneaud et al.18 have reported the synthesis of pento-cystine, [ HO,C*CH ( NH2)*( CH,),*S-], , and homomet hionine,CH,*S*(CH,),*CH(NH,)*CO,H, but so far no report of their meta-bolic effects has appeared.Tryptophan.-It is interesting tn view of the specific growtheffect of I-cystine, that the stereoisomeric forms of tryptophanare equally effective in promoting the growth of rats.l9 Acetylation,however, introduces specificity, since acetyl-d-tryptophan is notutilised as a growth promoter (possibly because it is not easily hydro-lysed in the body).Neither d-tryptophan nor its acetyl derivativeleads to kynurenic acid excretion, and acetylation considerablyl* J. A. Stekol and C. L. A. Schmidt, Univ. Calijornia Pub. Physiol., 1933,8, 31 ; A., 1934, 440.l5 J . Biol. Chern., 1934, 104, 59; A., 322.l6 Ann. Reports, 1933, 30, 333. *Biochem. J . , 1934, 28, 305; A., 440.l8 V.du Vigneaud, H. M. Dyer, C. B. Jones, and W. J. Patterson, J . Biol.lQ C. P. Berg, ibid., 1934, 104, 373; A., 440.Chern., 1934, 106, 401; A., 1094342 BIOCHEMISTRY.reduces the amount of kynurenic acid formed from the lzevo-isomeride. L. C. Bauguess and C. P. Berg20 found further thatp-3-indolylacrylic acid and a-oximino-~-3-indolylpropionic acidwere both without effect on growth and were not converted intokynurenic acid by the rabbit, Racemic p-3-indolyl-lactic acid,however, both supported growth and led to kynurenic acid excretion.Part of the amount fed was recovered from the urine (more of theE-compound than of the d-, which suggests a greater efficiency of the&-acid). p-3-Indolylpyruvic acid was also converted into kynurenicacid, and was not recoverable from the urine.The same authors 21found that amides of Z-tryptophan support growth and yieldkynurenic acid. These results suggest, of course, that, whatevermay be the mechanism of the growth-promoting action of trypto-phan, it involves the formation of an optically inactive compound,presumably the corresponding ket o- acid.R, S. A1cock,22 indeed, points out that kynurenic acid formationis probably a side or " shunt '' reaction (possibly a detoxicatingmechanism) dealing with excess of tryptophan by way of indole-pyruvic acid ; the ease with which various tryptophan derivativesyield kynurenic acid is no more than a measure of the ease withwhich they are converted into the keto-acid. He finds that rats ona tryptophan-deficient diet do not grow when tryptophan is injected,but do grow when given small daily doses of the anterior pituitarygrowth hormone (0.1-0.15 ml.of the extract per day, injected).He suggests that the animal can synthesise tissue proteins withoutreceiving tryptophan in the diet, but that it requires tryptophan forthe synthesis, in the liver, of some substance essential to life.Histidine.-S. Edlbacher and M. Neber,23 in a further study of thebreakdown of histidine by histidase, consider that the reactioninvolves the opening of the glyoxaline ring with addition of 2H,Oand formation of ammonia and o-formylglutamine. The product ofenzyme action is hydrolysed by sodium hydroxide to ammonia,formic acid, and glutaminic acid, and on oxidation with hydrogenperoxide it gives succinic acid semialdehyde, as does glutaminicacid.Amino-mid Anhydrides.-It is perhaps invidious t o single outany one item from the mass of interesting work on peptides and theirhydrolysis by enzymes, but the subject 8s a whole seems hardlyready for review. A point of particular interest, however, is thepossibility of the occurrence of djketopiperazines in the proteinmolecule.The great obstacle to the acceptance of this possibility2o J . BioE. Chem., 1934,104, 675, 691; A., 554.21 Ibid., 1934, 106, 615; A., 1252.z3 2. physiol. Chern., 1934, 224, 261; A., 920.22 Biochern. J., 1034, 28, 1721STEWART AND POLLARD. 343has been the failure of proteolytic enzymes to hydrolyse diketo-piperazines.Recently, however, K. Shibata 24 has obtained foursubstituted diketopiperazines which underwent enzymic hydrolysis,and two of these contained only naturally occurring amino-acids.CHR-CO Glycyldiaminopropionic anhydride, NH<c-,CHR,>NH (R = H,R’ = CH2-NH2), and diaminopropionic anhydride (R = R’ =CH,*NH2) were hydrolysed by pepsin ; and glycylglutaminicanhydride (R = H, R’ = CH,*CH,*CO,H) and asparagine anhydride(R = R‘ = CH,-C0,H) were hydrolysed by trypsin, cathepsin, andpapain.Indirect Calorimetry.Last year, E. P. Poulton 25 amplified a previous note 26 on certainerrors in the measurement of heat production by calculation fromthe gaseous exchange using the ZuntzSchumburg factors. Hefound that, though the heat produced was proportional to the carbondioxide, the correlation between heat production and oxygen usagewas bad.There is, he Bays, considerable variation in the oxygenconsumption-the heat and the carbon dioxide production remainingconstant-but on the whole the amount of oxygen used is unex-pectedly small a t R.Q. above about 0.8, and unexpectedly highbelow that level. He suggests that under basal conditions there isactually a constant combustion ratio of carbohydrate to fat, andthat the errors in calculating the heat production from the oxygenconsumption are to be explained by the use of oxygen for partialoxidations or its liberation in reductions, whereas the carbon dioxideproduction represents complete oxidations.One of the most obvious of incomplete oxidations is, of course,the formation of carbohydrate from fat, and the vexed question ofwhether this does or does not occur in the animal body still receivesattention.The great criticism which is directed against all attemptst o prove this conversion is that they depend upon measurements ofthe R.Q., and that even if the accuracy of the measurements begranted, alternative explanations may still be possible. In adiposesubjects undergoing dietetic weight reduction, where conditions forsugar formation from fat ought t o be ideal, V. Forbech and F.Leegaard 27 found that the carbohydrate metabolised frequentlyexceeded the intake, and that the low R.Q. supported the idea thatfat was converted into carbohydrate. In both man and the pig,24 Actu Phytochirn., 1934, 8, 173; A., 1260.25 Proc.Roy. SOC. Med., 1933, 20, 1591.26 T. W. Adame and E. P. Poulton, J . Physiol., 1932, 77, (Proc.) 1.27 Acta, Med. Xcand., 1934, 81, 351; A., 1025344 BIOCHEMISTRY.following high fat diets, Hawley et aLZ8 found values of the R.Q.too low to be accounted for by ketosis or by carbohydrate formationfrom protein or glycerol.find that, contrary to the usual view, only 30% or less of glycerolis converted into glucose.) They found considerable individualvariation, the occurrence of a low R.Q. depending less on theamount of fat in the diet or the carbohydrate/fatty acid ratio thanon the tolerance of the subjects. They point out that otherexplanations than that of glucose formation from fat are conceivable,and direct attention t o the effect of cold in producing a low R.Q.andto the specific dynamic action of butter fat.J. M. Peterson30 has compared the R.Q. in decerebrate and indecerebrate eviscerate cats, with corrections for displaced carbondioxide. He finds that the true oxidative R.Q. in decerebrateeviscerate cats is about 0.825, and calculates the R.Q. of the removedviscera to be 0.69, a value which he considers to be associated withliver gluconeogenesis .The subject of carbohydrate production from fat has been critic-ally reviewed by H. H. Mitchell,31 but the work reported during thepast twelve months has not forced acceptance of such a productionupon the sceptical. As J. Needham 32 points out in dealing withoxygen consumption without carbon dioxide production in acidifiedhen or crab eggs, such a phenomenon may be due to a variety ofcauses other than the production of sugar or keto-acids from fats;e.g., oxidation of sulphur to sulphate, of lactic acid to pyruvic acid,of glucose to glycuronic acid. It is, however, doubtful whetherthese, in man, are of sufficient quantitative importance to accountfor the low values of the R.Q.which have been recorded.(F. H. Lashmet and L. H. NewburghHeavy Water.The biological behaviour of D,O is receiving attention, though,naturally, not a great deal of progress has yet been made. Never-theless, a number of short papers have appeared which combine togive the impression that living cells are by no means indifferent tothe proportions of H,O and D,O in the surrounding media, and thata normal concentration of heavy water may be essential to the pro-cesses of life.The fact that pure D,O is definitely toxic and kills certain small38 E. E.Hawley, C. W. Johnston, and J. R. Murlin, Amer. J . Physiol.1933, 105, (Proc.) 46; A., 1934, 441; J . Nutrition, 1933, 6, 523; A . , 1934,320.29 J . Clin. Invest., 1933, 12, 968.80 J. Phyfliol., 1933, 79, 508; A., 1934, 683.a 1 J . Nutrition, 1933, 6, 473.32 Proc. Soc. Exp. Biol. Med., 1932, 30, 182; A., 1933, 1324STEWART AND POLLARD. 345organisms a t a rate generally proportional to their degree of com-plexity was reported last year.33 G. N. Lewis,% however, statesthat the toxicity is not very great to such varied organisms astobacco seeds, yeast, flatworms, and mice; and lower organismstolerate it in high concentrations.He finds that the rate of thevital processes is roughly inversely proportional to the concentrationof D,O, and that in pure D,O growth is extremely slow if it takesplace at all.Even low concentrations of heavy water have a definite effect oncellular metabolism and on enzyme systems. T. C. Barnes35found that in water of d 1.000061, filaments of Spirogyra nitidawere characterised by lack of movement, absence of abscission orcell disjunction, and greater longevity. Later,36 he reported that inheavy water (d 1.000061) a filament of 31 cells of Xpirogyra nitiduhad increased to 43 cells (3 dead) after six days, whereas in ordinarywater under,&nilar conditions no cell division had taken place, inice-water there were 15 abnormal cells out of 50 after five days, andin freshly condensed water all the cells died.Similarly he 37 foundcells of E. gracilis to multiply more rapidly in water containing alow percentage of D,O than in ordinary distilled water, and astimulating effect of D,O (in small concentrations) on the vegetativegrowth and development of Aspergillus sp. has been reported byS. L. M e ~ e r . ~ ~Dealing with enzyme systems, Barnes and Larson found thatheavy water (d 1.000061) decreased the rate of starch hydrolysisby pancreatic amylase, and the amount of carbon dioxide evolvedduring zymase fermentation. OQ the other hand, oxidation ofguaiaconic acid by a peroxidase-oxygenase system was increased bymaking the solution in ice-water and allowing it to warm to roomtemperature.H.Erlenmeyer and H. Gartner 39 find that, within experimentalerror, the animal body does not change the D,O content of water,since 8 litres of pure water yielded 20 C.C. of heavy water of d 1.00087,and cow’s milk similarly treated gave water of d 1.00083. This is,of course, an important observation for those workers who use heavywater as an indicator of water movement in the animal body, Thishas been done in the case of fish (goldfish), in which it appears thatnearly all the water leaves the body and is replaced by fresh withinAnn. Reports, 1933, 80, 34.34 Science, 1934, 79, 153; A., 557.35 J . Amer. Chem. SOC., 1933, 55, 4332; A., 1933, 1329.36 T.C. Barnes and E. J. Larson, {bid., p. 5059; A., 1934, 217.Science, 1934, 79, 370; A,, 692.38 Ibid., p. 210; A., 562. 89 H e b . Chirn. Acta;, 1934, 17, 334; A., 540346 BIOCHEMISTRY.a few hours,40 and in man, where the exchange takes many days.In man, G. von Hevesy and E. Hofer 4 1 found that half the ingestedheavy water was excreted in 9 (-+ 1) days, and calculated the average" life " of a water molecule within the body to be 13 (& 1-5) days.Their calculations involved the assumption that the ingested waterwas completely mixed with the water present in the body, and thisassumption has been verified by H. Erlenmeyer et ~ 1 . ~ ~ Theseworkers found that injection of isotonic heavy water (1.64%)solutions of xylose into jejunal loops of rats led to reduction of theheavy water content to 0*05--0-07% without diminution of the totalvolume.Calculation showed that this meant the distribution of thoheavy water over 127-135 c.c., the total water content of the bodybeing 132 C.C. The absorption was very rapid, the figures quotedbeing obtained in one hour.PLANT BIOCHEMISTRY.Fixation of Nitrogen by Nodule Bacteria.Investigations of the symbiotic relationships between leguminousplants and Rhixobia, culminating in recent years in the developmentof practical methods of field inoculation, have brought in their traina much wider knowledge of the nutrition and metabolism of thesebacteria. Contrary to earlier views, it is now firmly established thatthe nodule bacteria are unable to fix nitrogen in the absence of thehost plant.112, 3 Moreover, the organism, previously supposed to bestrictly aerobic, has been shown to maintain its activity underanaerobic conditions in the presence of a hydrogen-acceptor.Itsgrowth in nodules in which the oxygen supply is, to say the least,much restricted, now receives adequate explanation.The general association of rapid vegetative growth in legumes withextensive nodule formation in the roots has led to many investig-ations of the balance between the ability of the plant to supply car-bonaceous energy material to the nodule bacteria and that of thebacteria to provide assimilable nitrogen for the plant. In thisconnexion, P. W. Wilson and colleagues*, 5, 6 have examined the40 G.von Hevesy and E. Hofer, Nature, 1934, 133, 495; A., 557.4 1 Ibid., 1934, 134, 879.42 H. Erlenmeyer, H. Gartner, E. J. MacDougall, and F. VerzBr, ibid.,1 P. W. Wilson, E. W. Hopkins, and E. B. Fred, Arch. Mikrobiol., 1932,p. 1006.3, 322; A., 1932, 549.F. E. Allison, J. Agric. Res., 1929, 39, 893; B., 1930, 258.3 M. P. Lohnis, Soil Sci., 1930, 29, 37.4 P. W. Wilson, E. B. Fred, and M. R. Salmon, &ad., 1933, 35, 145; B.,P. W. Wilson, P. Wenck, and W. H. Peterson, i b d , p. 123 ; B., 1933,323.P. W. Wilson and E. B. Fred, J . Bact., 1033, 25, 64; A., 1933, 647.1933, 323STEWART AND POLLARD. 347frequently observed beneficial effect of an artificially increasedproportion of atmospheric carbon dioxide on the growth andnodulation of legumes.With Rh. trifoliurn it is shown that in anormal atmosphere the rate of carbon assimilation by red clover,rather than that of nitrogen fixation by the bacteria, is the limitingfactor in this symbiotic system. With a carbon dioxide content ofapproximately 0.3 yo, carbon assimilation reaches an intensitysufficient to meet the energy requirement of the nodule organismsfor maximum fkation of nitrogen. The critical carbon dioxidecontent for balanced conditions depends on external conditions,notably those controlling the difference between the intake andrespiration of carbon dioxide, and the rate and extent to whichcarbon dioxide liberated by the bacteria can diffuse through thegrowth medium and again become utilisable by the leaves. In-creased assimilation results not only in an increasing growth andnitrogen content of the plant and a greater number of nodules, butin enlargement of the nodules and a tendency for their normal dis-tribution round the crown of the roots to be extended to lateralroots.By increasing the pressure of carbon dioxide around sand-culturedplants, C. E.Georgi, 3'. S. Orcutt, and P. W. Wilson find that allthe above effects are accentuated even if the total amount of carbondioxide to which the plant has access remains unchanged. Theproduction of similar effects by the addition of sucrose or glucose toculture media is attributable to the utilisation of the sugars by thebacteria and to increased carbon assimilation of the plant followingthe production of carbon dioxide by the organisms.Mamito1produces no such effects and even in moderate concentrationsdepresses nitrogen fixation. In an examination of soya bean organ-isms, F. Allam 8 calculates that approximately 15 g. of dry matterfrom the plant are consumed during tbe fixation of 1 g. of nitrogen.More recently E. B. Fred and P. W. Wilson9 confirm the directrelationship between the carbohydrate content of clover and thenumber of nodules formed, and further show that excessive amountsof sugars in the early stages of growth may cause a temporarilydelayed fixation of nitrogen.A reduced supply of carbohydrate, e.g., when plants are kept indarkness, checks fixation by the bacteria, which then attack thecellulosic matter of the plant tissues.10 Sugar metabolism inRhixobia takes the form of a butyric fermentation with the7 Soil Sci., 1933, 36, 375; B., 1934, 114.2.PJEanz. Dung., 1931,20, A , 270; A., 1931, 876.Proc. Nat. Acccd. Sci., 1934, 20, 403; A., 1273.1" H. G. Thornton, PYOC. Roy. SOC., 1930, B, 106, 110348 BIOCHEMISTRY.production of the customary proportions of carbon dioxide andhydrogen and small amounts of alcohol and acetic acid.llBy providing an alternative source of nitrogen to clover,E. W. Hopkins and E. B. Fred l2 find that the size of root nodules isdecreased to extents which vary with the nature of the materialused, but, in general, vary inversely with concentration of thenitrogen source (potassium nitrate, ammonium sulphate, urea,asparagine, and yeast extract are examined).Under these condi-tions nodules are found principally on lateral roots. In the pre-sence of mannitol and either nitrogenous substance nodulationis largely confined to tap roots.The high specificity of the various species of Rhizobium in respectof the host plant, sufficiently accentuated to permit the use ofagglutination and complement -fixation tests for classification pur-poses,13 is reflected, to some extent, in their response to differentforms of fixed nitrogen. Thus R. H. Walker and D. A. Anderson l5record that the oxygen consumption of cultures of four differentspecies is uniformly low in nitrogen-free media, but is increased, byadditions of yeast extract, in proportion to the amount of nitrogenthus added. The effect is maintained until the supply of nitrogen isexhausted.If, however, nitrogen is added to cultures of Rh.leguminosarum, Rh. trifolii, or Rh. phaseoli in the form of sodiumnitrate or alanine, there is only a small upward trend in oxygenconsumption. With ammonium chloride or urea, small concen-trations produced little or no effect and larger amounts had adepressive action. The growth and activity of Rh. meliloti weredefinitely increased by all forms of nitrogen examined, the actionof urea being intermediate between that of yeast (high) and that ofthe remaining three simpler compounds, which produced generallysimilar effects. Characteristic physiological differences betweenRh. meliloti and other species are shown by A. W. Hofer andI. L. Baldwin16 to develop in media rich in nitrogen.The decomposi-tion of various nitrogenous compounds by different nodule organismsis also examined by G. G. Pohlman ; l7 Rh. meliloti produces ammoniafrom glycine, dl-amino-n-butyric acid, dl-alanine, asparagine, andurea, whereas Rh. japonicum acts only on the last three substancesl1 A. I. Virtanen, M. Nordlund, and E. Hollo, Biochern. J., 1934, a, 796;A,, 928; Suomen Kern., 1933, 8, B, 62; A., 1933, 752.la Plant Physiol., 1933, 8, 141; A., 1933, 647.l3 W. R. Carroll, Soil Sci., 1934, 37, 117, 227; A., 453; B., 468.l4 J . Bact., 1933, 25, 53; A., 1933, 638.l5 With P. E. Brown, Soil Sci., 1934, 37, 387; A., 811; ibid., 1934, 38,l6 J . Bact., 1932, 23, 65; A., 1932, 1066.l7 Soil Sci., 1931, 31, 385; A., 1931, 876.207; A., 1265STEWART AND POLLARD.349named. Differences in the utilisation, without ammonia formationof the amino-groups in glycine, 1-tyrosine, dl-amino-n-butyric acid,and urea are also shown by these two species. It is not yet clear,however, to what extent these differences are characteristic ofspecies. In some cases, various strains of the same species appearto vary in their action on nitrogen compounds.The diffusion of bacterial nitrogen from nodules into the surround-ing soil and its ultimate utilisation by other plant species arematters of obvious practical importance. The implied breakdownof the bacterial cell is variously ascribed to the action of plantenzymes or to the presence of a specific bacteriophage within theroot.According to A. I. Virtanen and S. von Hausen,ls thediffused nitrogen is almost entirely in the form of amino-acids,which are effective sources of nitrogen for Grumineue. In mixedcrops of peas and oats, the latter obtained additional nitrogen if theproportion peas : oats was between 1 : 1 and 1 : 2. With smallerproportions of peas, the growth of both crops was depressed.19H. G. Thornton and H. Nicol20 show a similar utilisation of nodule-nitrogen to occur in rye grass when grown simultaneously withlucerne.Biochemistry of the Higher Plants.Nitrogen Nutrition and Metabolism.-The great practical andacademic interest in the nitrogen relationships of plants is reflectedagain this year in a heavy output of research work on this subject.The relative efficiency of nitrates and ammonium salts in plantnutrition continues to form the basis of many investigations inwhich the varying aspects of this intricate problem are being steadilyelucidated.Continuing earlier work,21 Shive and his colleagues 22 show thatammonia intake by the tomato, as by other plants, is most rapidfrom neutral or alkaline media, and that of nitrate from acid media.In older plants, however, the absorption of nitrates becomes lessaffected by pH, and, in the range pH 4.0-7.0, usually exceeds that ofammonia at any given pH.Further, the rate of absorption ofammonia per gram of dry matter in the plant decreases, whereasthat of nitrate increases with advancing plant growth. Inammonium nitrate-fed plants the proportion of ammonia in roots2. Pjlanz.Dung., 1931,21, A , 57; A., 1931, 1101; Szcomen Kern., 1933,6, 23, 55; B., 1933, 243; (with H. Karstrijm), Biochem. Z., 1933, 258, 106;A., 1933, 437.19 U. Wartiovaara, Z. Pjlanz. Dung., 1933, 81, A , 353; A., 1933, 1092.2o J . Agric. Sci., 1934, 24, 269; B., 550.2 1 Ann. Reports, 1933, 30, 320.22 H. E. Clark and J. W. Shive, Soil Sci., 1934, 37, 203, 459; B., 468, 776350 BIOCBEMISTRY.increases with the p= of the medium, and the simultaneous appear-ance of large amounts of basic-free amino-nitrogen indicates rapidtransition of ammonium- to amino-nitrogen within the root system.This is confirmed by the relatively small effects of changes in therate of ammonia absorption on the ammonia contents of leaves.I n these experiments, also, the nitrate content of roots, stems, andleaves was but little changed as a result of variations of and ofnitrate intake.It would appear, therefore, that conditions favour-ing the intake of ammonia or nitrate are also those favouring theassimilation of the respective nitrogen sources. The high proportionof nitrate in stems as compared with roots or leaves of tomato istypical also of a number of other plants.23 I n a somewhat similarinvestigation of sand-cultured peach trees 0. W. Davidson andJ. W. Shive 24 show that optimum utilisation of ammonium saltsoccurs with media of pH 6.0, whereas that of nitrate shows twooptima, at pE 4.0 and 8.0. Here again the early stages of ammoniaassimilation occur in the roots, in which also the reduction of nitrateis practically completed.V. A. T i e d j e n ~ , ~ ~ working with tomatoand with apple, codrms many of the observations of Shive and alsoshows that ammonia-fed plants contain more soluble organic nitro-gen than those receiving equivalent proportions of nitrate. Highproportions of soluble carbohydrates apparently favour ammonium-assimilation.A comparison of the relative effects of different nitrogen sourceson soil cultures of a number of farm crops is recorded by K. Nehring.26With acid-sensitive plants, e.g., mustard, ammonium sulphateproduces better growth than nitrates at all ranges of pH examined.A slight advantage is shown by ammonia in alkaline and by nitratein acid conditions for the development of barley, wheat, and maize.At neutrality no differences are apparent.The nitrogen intakefrom the various sources, by acid-tolerant plants (oats, rye), is notgreatly affected by pH, and although differences in the growth ofammonia-fed and nitrate-fed plants are small, the latter containrelatively larger proportions of amides as compared with proteins.An interesting paper by J. P. Conrad2' records changes in thereaction of media as a result of the growth in them of maize andsorghum plants. The residual (titratable) acidity of culturescontaining ammonium sulphate, after absorption of the nitrogen by23 E. Parisi and G. de Voto, Atti R. Accad. Lincei, 1932, 16, 270; A., 1933,197.24 Soil Sci., 1934, 37, 357; A,, 821.25 Phnt Physiol., 1934, 9, 31; A., 821.26 Landw.Jahrb., 1934, 79, 481; B., 728.27 J . Amer. Soc. Agon., 1934, 26, 364; A., 1048STEWAXT AND POUARD. 351plants, is greater than that in corresponding media containingsulphuric acid, and the alkalinity of sodium nitrate cultures is lessthan that of sodium bicarbonate cultures. The residual values fornitric acid, ammonium nitrate, and ammonium carbonate media areall practically the same as when water alone is used. These resultsare attributed to the necessity of the plant to utilise hydroxyl ionsduring the assimilation of ammonia, and hydrogen ions for assimil-ating nitrates. It is suggested that the energy utilised in the absorp-tion of the hydroxyl or hydrogen ions is a factor controlling the effectof a on the proportional absorption of nitrate and ammoniumsalts.D. Prianischnikov 275 shows that ammonium nitrate innutrient media may exert a physiologically acid or alkaline reactionin accordance with the age of the plants and the concentration of thenutrient. Under conditions of excessive alkalinity, absorbedammonia may be re-excreted into the medium. The physiologicalreaction of ammonium nitrate is also influenced by temperature,since nitrate absorption increases with rising temperature, whereasthat of ammonium is unaffected.28Temperature effects on the nitrogen nutrition of apple areexamined by G. T. Nightingale.f9 Simple protein synthesis occursin the fibrous roots of trees grown in darkness, in sand cultures a t9", nitrogen being supplied as ammonium sulphate at pE 6.0 orsodium nitrate at pE 4.5.Formation of amino-acids and aspara-gine and the utilisation of carbohydrate proceed more rapidly in theammonia-fed plants. Protein formed at this temperature, however,remains in the roots, which develop rapidly. By increasing thetemperature to 21", translocation of amino-acids to buds beginsand these organs develop rapidly. The reaction of the internalroot tissues is unaffected by that of the nutrient media or the natureof the source of nitrogen. I n several leguminous plants examinedby L. Burkhart 30 the absorption of ammonium salts appears to beinfluenced to a considerable extent by the nature of the non-nitro-genous plant reserves. Ammonia injury in these plants resultsfrom interference with the normal process of utilisation of proteinand non-protein reserve substances, and is associated with lowproportions of reducing sugars. Amide detoxication is onlymoderately effective in reducing injury.The ammonia nutrition ofrice varies with the nature of the associated anion, absorptiondecreasing in the order sulphate, phosphate, nitrate, chloride.The differences persist throughout growth except in the case of the270 2. PJEanz. Dung., 1934, A, 33, 134; B., 417.28 P. Strebeyko, Polish Agric. Forestal Ann., 1932, 28, 357; A., 1934, 821.29 Bot. Gaz., 1934, 95, 437; A., 1044.30 Plant Physiol., 1934, 9, 351; A., 1273352 BIOCHEMISTRY.nitrate, the ammonia of which is relatively better assimilated inolder plants.31 Sugar cane plants supplied with ammonium saltsare observed by G.B. Ulvin 33 to produce less chlorophyll than thosereceiving nitrate.Carbohydrates in Plants.-Starch formation in sugar cane leaveshas been further examined by W. M. Coelingh and V. J. Konings-berger.33 Normally, starch accumulates only in the bundle sheaths.The process continues in darkness if excised leaves are placed insolutions of maltose, sucrose, glucose, or fructose, but starch pro-duction is localised in the palisade cells of the parenchyma. Lightis required for the translocation of starch to the bundle sheaths.The extent to which these processes occur differs somewhat with thevariety of cane examined. During the growth of the cane seasonalvariations in total solids and non-reducing sugars in the sap are of asimilar character, whereas reducing sugars vary in an inversedirection. I n cooler periods sucrose accumulates in stems and maybe utilised during the sprouting of stem cuttings, during tassellingand side-shoot formation, or in the renewal of denuded leaves,During such periods the proportion of reducing sugar in saps under-goes little change.34In an interesting investigation of the distribution of carbohydratesand other constituents of the cotton plant, T.G. Mason andcolleagues 35, 36 examine the concentration gradients of sugars invarious organs under different growth conditions. I n addition tosucrose, glucose, and fructose a water-soluble polyglucoside occursin leaves. Translocation of carbohydrate to the bundles occurs inthe form of sucrose.Stored polysaccharides are located chiefly inthe bark.I n the examination of carbohydrate changes in plants the practiceis frequently adopted of comparing analytical values on a total-dry-weight basis. F. E. Denny37 indicates that this may sometimeslead to quantitative or even qualitative error and advises the calcu-lation of data in terms of “ residual dry weight,” i.e., total dry weightrniizus carbohydrates.The significance of sugar accumulation in vines is examined byL. Rloreau and E. V i r ~ e t , ~ ~ who show that the rapidly increasingB., 1934, 33.31 R. H. Dastur and T. J. Mnlkani, Indian J. Agric. Sci., 1933, 3, 157;a3 Arch. Suikerind. Ned.-Indie, 1932, 1325 ; A., 1934, 464.34 S. Komatsu, S. Ozawa, and Y.Makino, Mem. Coll. Sci. Kyoto, 1933,36 E. Phillis and T. G. Mason, Ann. Bot., 1933, 47, 585; A., 1933, 988.36 T. G. Mason and E. J. Maskell, ibid., 1934, 48, 119; A., 335.37 Contr. Boyce Thompson Inst., 1933, 5, 181 ; A., 1933, 873.32 Plant Physiol., 1934, 9, 59; A., 818.A , 16, I ; A., 1933, 873.Ann. agron., 1932, 3, 363; A . , 1033, 102STEWART AND POLLARD. 353amount of sugar appearing in the fruit during ripening is obtainedvery largely from the carbohydrate reserves of the main stem.Moreover, sugar acdumulation in the sap is a controlling factor inthe development of new fruit buds. Variation in the carbohydratecontent of roots is discussed by A. C. from the practicalviewpoint of the importance of timing cutting operations in weederadication.The effect of disease on carbohydrate variations in plants formsthe subject of numerous investigations.Leaf-roll in potato disturbsthe normal translocation of sucrose as a result of damaged phloem,and although there is some passage of hexose through the paren-chyma, starch steadily accumulates in leaf lamin~e.40 Tobacco virusbrings it decline in leaf ~arbohydrate,~~ differences from normalbeing especially marked in periods of active photosynthesis. Duringthe storage of healthy leaves there is a, steady decrease in insolublecarbohydrates, whereas in diseased leaves the loss falls principallyon the disaccharide fraction.42Rust in wheat causes a reduction in the percentage of sucrose andan increase in that of starch in the grain, although the total starchper grain is subnormal.&Other observations of this character include the occurrence of ageneral increase in reducing sugars, sucrose, starch, and poly-saccharides in the leaves of lucerne and clover following injury bythe leaf hopper;44 a partial replacement of carbohydrate bypentosans and galactan in rutabagas exhibiting “ dark centre ” ;and the association of ‘‘ blind wood ” in roses with abnormallyhigh accumulation of insoluble carbohydrates in stems and leaves,as compared with the flowering shoots which contain large pro-portions of reducing sugars.GZucosides.-Seasonable variations in cyanogenetic-glucoside con-tent of Xorghum vulgare are recorded by C.N. A ~ h a r y a . ~ ~ Maximumyields of hydrocyanic acid were obtained from very young plantsor young, actively growing side shoots of older stocks.The pro-portion declined with advancing age to a minimum a t the flowering3% Minnesota Agric. Exp. Sta. Tech. Bull., 1932, No. 84; A., 1933, 328.40 E. Barton-Wright and A. McBain, Trans. Roy. SOC. Edin., 1932, 57,4 1 J. Caldwell, Ann. Appl. Biol., 1934, 21, 191, 206; A., 1030.42 H. Cordingley, J. Grainger, W. H. Pearsall, and A. Wright, ibid., p. 78;A., 466.43 R. M. Caldwell, H. R. Kraybill, J. T. Sullivan, and L. E. Compton,J. Agric. Res., 1934, 48, 1049; B., 978.44 H. W. Johnson, Phytopath., 1933, 23, 19; B., 1933, 565; E. B. Hollandand C. P. Jones, J. &Tic. Res., 1934, 48, 377; A., 822.45 Indian J . Agric. Sci., 1934, 3, 851; A., 710.309; A., 1933, 546.REP.-VOL.XXXI. 354 BIOCHEMISTRY.stage. Cyanogenetic material accumulates chiefly in leaves andthe yield is the same whether seedlings are grown in darkness orin daylight. Daily variations show minima in early morning andevening and a maximum soon after mid-day. In the preparationof material for analysis, treatment with chloroform or toluenedoes not check the enzymic liberation of hydrocyanic acid. Thepossibility of the presence in Xorghum of cyano-compounds otherthan glucosides is indicated. A daily periodicity in the glucosidecontent of Aesculus leaves is reported G. Kerstan,46 who makesthe interesting observation that ssculin in the bark of twigs is noteasily translocated and does not function as a carbohydrate reserve.In leaves, however, zesculin is mobile.An unusual practical applic-ation of glucoside 'analysis is indicated by an examination of NewZealand clovers. It is shown that the amount of hydrocyanicacid obtainable from individual types, although subject to seasonalvariations, falls within limits sufficiently narrow to permit differ-entiation among different types?', 48 H. 0. Askew 49 also describesa mtisfactory method for the preparation and analysis of thematerial.Among new examinations of glucosides in plants may be mentionedthose of H. Colin and A. Chadun,SO who isolate a fructoside fromScilla, of G. Tanret 51 on the nature of coronillin from Coronilhseeds, the preparation of kzempferol rhamnoside from leaves ofPueraria h i r s ~ t a , ~ ~ and a further examination of salireposide 53 byM.W a t t i e ~ , ~ ~ who now describes this substance a8 a benzoate ofa heteroside yielding p-glucose on hydrolysis.Mineral Nutrition.-Potassium. That the efficiency of potassiumin plant nutrition is influenced by the nature of associated cationshas long been recognised. E. Blanck and W. Heukeshoven 55 makethe rather unexpected observation that the yield response of beansto potassium is higher for the oxalate, citrate, and formate than forthe sulphate. Moreover, the anionic influence shows itself notonly in affecting the total intake of calcium, phosphorus, and nitro-gen, but also in the distribution of these elements between seed and46 Planta, 1934, 21, 676; A., 1048.47 B. W. Doak, New Zealand J .Sci. Tech., 1933, 14, 369; B., 1933, 839.4 8 T. Rigg, H. 0. Askew, and E. B. Kidson, ibid., 1933,16, 222; A., 1934,4s I b d . , p. 227; A., 229.50 Bull. SOC. Chim. biol., 1933, 15, 1520; A., 1934, 464.5 1 Cornpt. rend., 1934, 198, 1637; A., 709.52 T. Ohira, J . Agric. Chem. SOC. Japan, 1933, 0, 337; A., 1933, 1216.53 Ann. Reports, 1931, 28, 244.54 Bull. Acad. roy. mkd. Belge, 1932, 12, 433; A., 1934, 1276.5 5 J . Landw., 1933, 31, 291.229STEWART AND POLLARD. 355straw. This is perhaps related to the fact that the utilisation ofcalcium phosphate by plants to which the various salts were appliedis paralleled by the solubility of calcium phosphate in the respectivesalt solutions. In an examination of the distribution of potassiumin potato plants W.0. James and N. L. Penston 56 indicate acontinuous circulation of potassium in the plant in the form ofsalts of amino-acids. Deficiency of potassium lowers the activityof enzymes in plants and also the relative order of activity invarious plant organs. Thus M. Cattle 57 establishes that lowereddiastatic activity is more pronounced in young and in old leavesthan in those of intermediate age. Similarly, invertase activityin upper leaves is diminished and that of lower leaves increased bypotassium starvation. The decline in invertase activity has alsobeen observed in sugar cane by C. E. Hartt.58 The well-knownrelationships between the formation of carbohydrates in plants andthe supply of potassium suggest, that light intensity may exerta controlling influence in potassium nutrition.K. Scharrer andW. S ~ h r o p p , ~ ~ working with peas, show an inverse relationshipbetween the optimum potassium requirement and the period ofexposure of the plants to light. Impoverished growth due todeficiency of light is to a considerable extent counteracted by in-creased feeding with potassium. Similar conclusions are reachedby R. Schwartz 60 in the course of field manurial trials of the effectof potash fertilisers on the seed yield of Lolium italicurn.Iron and mnganese and their relation to chlorosis. The appearanceof chlorosis in plants is frequently traced to deficiencies within theplant of iron or manganese and since the solubility of many soilminerals containing these elements is lowered by reaction changestowards alkalinity, the explanation of lime-induced chlorosisseemed a simple one.Recent investigations indicate that otherfactors are concerned. The intake of manganese 61, 62+and iron 83by plants is conditioned by the nature of the compounds concernedand by the presence of other substances. Thus the absorption ofmanganese from the dioxide by wheat seedlings is depressed byadditions to nutrient media of sodium nitrate and calcium carbonate.No depression occurs when manganese chloride is used. Thereduced intake caused by additions of phosphate is especially marked56 Ann. Bot., 1933, 47, 279; A., 1933, 649.67 New Phylol., 1933, 32, 364; A., 1934, 337.58 Hawaiian Planters Rec., 1933, 37, 13; B., 1934, 340.5D 2.Pfinz. Dung., 2934, A , 35, 186; B., 1075.6o Ernahr. P&nze, 1934, 30, 293; B., 1027.61 J. Davidson, Proc. 2nd Internat. Cong. Soil Sci., 1933,11,84; A,, 1934,337.62 C. Oleen, Compt. rend. Trav. Lab. Carlsberg, 1934,20, No. 2 ; A., 1048.63 W. Schropp, 2. Pfinz. Dung., 1934, A, 33, 38; B., 340366 BIOCHEMISTRY.in the case of manganese chloride and sulphate. Similar influenceof anions on the absorption of iron by plants is also described.The availability to plants of organic compounds of iron is found tobe much less affected by reaction changes than that of manyinorganic forms .Extensive investigations in Germany 641 65, 66 of chlorosis in theyellow lupin indicate that the effect of lime is not limited to restrictingthe intake of iron by plants, but extends within the plant systemitself, where the iron is rendered immobile in the older leaves.Young leaves become chlorotic even when the total amount of ironwithin the plants may be sufficient t o meet their requirements.In the case of the blue lupin iron deficiency is related to the presenceof manganese, which is an essential nutrient for this plant.W.Scholz 67 shows that excessive proportions of manganese in theblue lupin plant produce no injury provided a sufficiency of iron ispresent. If the iron supply is restricted, as in lime-chlorosis,manganese intensifies the injury. Deficiency of manganese in theplant, however, may cause a characteristic manganese-chlorosisdistinct from that resulting from shortage of iron.Lime-inducedchlorosis is also observed in flax,68 and in this case also, the customarytreatment of the soil with iron salts is rendered inoperative if muchmanganese is present in the plant.A magnesium-chlorosis may occur as the result of excessiveapplications of magnesium carbonate to soils.69 It resembleslime-chlorosis in being associated with iron deficiency in leaves, andin its response t o additions of iron salts to soil.Copper. F. G. Anderson 70 cites a case of chlorosis due to copperdeficiency in leaves, remedied by spraying with copper sulphatesolution, and B. D. Wilson and G. R. Townsend 71 record the re-markably improved productivity of peat soils following treatmentwith copper sulphate. Similar effects were cbtained by R.V.Allison 72 and co-workers, in the saw-grass pea.ts of Florida. It issuggested in this case that in addition to its nutritional function,copper protects the root surface from injury by toxic organic64 R. Reincke, 2. Pjihnz. Dung., 1931, A , 23, 77; B., 1932, 126.68 W. Scholz, ibid., 1932, A , 25, 287; 1933, A , 28, 257; A, 29, 59; 1934,A , 33, 340; B., 1932, 907; 1933, 567, 599; 1934, 517.66 S. Triwosch, ibid., 1933, A , 31, 14; B., 1933, 884.67 Ibid., 1934, A, a, aa; B., 937.W. Scholz, ibid., 1934, A , 34, 296; B., 901.6D S. Triwosch, ibid., 1934, B, 13, 155; B., 597.70 J . Pomology, 1932, 10, 130; B., 1932, 907.71 J . Amer. Soc. Agron., 1933, 25, 523; B., 1933, 1073.7 2 Proc. 4th Cong. Int. SOC. Sugar Cane Tech. Bull., 1932, No. 112; B.,1933, 759; Proc.2nd Interat. Cong. Soil Sci., 1930, VI, 257; €3, 1933, 243STEWART AND POLLABD. 357substances known.to exist in these soils. Deficiency of copper isshown to be the cause of exanthema in pears 73 and of pecanrosette. 74Boron. Considerable interest centres on the essential nature ofboron for the growth of plants. The actual requirement (and alsothe minimum lethal dosage) varies considerably with species.Boron-deficiency affects the development of plants in a variety ofways, prominent among which is the curtailment of root growth,e.g., in flax,75 maize, and p ~ t a t o e s . ' ~ This effect is probably relatedto the influence of boron on thc calcium-intake of plants.K. Warington 77 shows that the addition of boron to nutrient solu-tions for Vicia fuba increases the gross amount of calcium .absorbed,and also prolongs the period during which the rate of intake ofcalcium is increasing.The direct relationship between the amountof calcium absorbed and that supplied is maintained aft,er borontreatment, but the general level of intake is raised. The normaldecline in the ratios N/Ca and K/Ca in plants with advancingmaturity appears to be accelerated by the presence of boron.Symptoms of boron deficiency appear more slowly in spring andautumn as a result of the shorter period of daylight. Temperatureis a less important factor in this re~pect.~8 The stimulatory actionof boron on root growth is shown by its ability to minimise theinjury to sugar beet caused by root and crown rots.7B Accordingto 0.Kaufmann,*o borax is much more efficacious than boric acidfor this purpose, and its protective action persists in soil for severalyears. E. V. Bobko and M. A. Bt:lvoussov81 record optimumgrowth of beet in nutrients conta.ining 5 mg. of boric acid per litre.The ill effects of heavy liming on the growth of beet in field soilsare counteracted by relatively small dressings of boric acid. In anexamination of a boron-deficiency disease of lettuce, J. S. McHargueand R. K. Calfee 82 show that boron may be added to culturemedia in the form of simple borates (that of manganese avoids toxiceffects) or as borosilicate in the form of powdered glass. Boric73 J. Oserkowsky and H. E. Thomas, Science, 1933,78, 315; A., 1934, 122.7 4 A.0. Alben, J. R. Cole, and R. D. Lewis, Phytopath., 1932, 22, 595;75 M. Skolnik, Bull. Acad. Sci. U.S.S.R., 1933, 7 , 1163; B., 1934, 463;76 K. Scharrer and W. Schropp, Z. PJEanz. Dung., 1933, 28, A , 313; B.,7 7 Ann. Bot., 1934, 48, 743; A., 1274.7 8 K. Warington, Ann. Bot., 1933, 47, 429; A., 1933, 989.79 K. Scharrer and W. Schropp, Landw. Jahrb., 1934, 79, 977; B., 1026.80 Deut. Zuckerind., 1934, 69, 305; B., 852.81 Ann. agron., 1933, 3, 493; B., 1933, 1073.82 Plant Physiol., 1933, 8, 304; B., 1934, 645.B., 1932, 954.Cornpt. rend. Acad. Sci. U.S.S.R., 1934, 2, 104; B., 597.1933, 518358 BIOCHEMISTRY.acid is essential to the development of pollen grains in certain tropicalwater lilies,a3 and borax is associated with marked stimulatoryeffect on the yield of beans.s4Plant Crowth-promoting Substances (Plant Hormones).It has long been realised that, although current knowledgeaffords an explanation in some detail of the chemical mechanismof nutrition, assimilation, metabolism, and synthesis in plants, themanner in which this mechanism is controlled and structural develop-ment regulated in response t o varied external conditions dependsupon characteristically different factors.Indeed it is only duringthe last few years that the activity of growth-regulating substances,hormones, auximones, etc., has been regarded as possibly due tospecific chemical substances. The spectacular work of F. Kogl andhis colleagues 85 in elucidating the chemical nature of auxin marksa very important stage of development in the subject and may wellform the source of inspiration of an enormous field of investigationfor the biochemist.Auxin- A.*Many aspects of plant development involve the elongation ofindividual cells (as distinct from their multiplication), and numerousinvestigators 86 have indicated that this process is influenced by ahormone-like substance which increases the plasticity of the cellwall and, possibly as a direct result of cell turgidity, thus facilitateselongation.The active material, auxin (so-named by K0gl),87 is usuallydetected and determined by its ability to promote renewed growthof Avena coleoptiles following decapitation.I n Went’s nowgenerally adopted technique, the auxin, prepared in agar, is appliedasymmetrically to the cut surface of the coleoptile stump and bycausing proportionally greater extension on the treated side, pro-duces a curvature which increases with the potency of the prepara-tion.The cuticle of the coleoptile is not readily permeable t o auxinin agar. Auxin readily penetrates the external tissue of roots,however, and here produces a restriction of elongation.S3 T. Schmucker, Naturwiss., 1932, 20, 839; A , , 1933, 105.8* M. Gorski, Polish Agric. Porestal Ann., 1932, 28, 27; B., 1934, 597.85 Ann. Reports, 1933, 30, 105.*6 Among others, see F. W. Went, Rec. Trav. bot. ne‘erl., 1928, 2 5 , l ; A. N. J.87 F. Kogl and A. J. Haagen-Smit, Proc. K. Akad. Wetensch. Amsterdam,* In the following pages the word “ auxin ” refers always to Auxin-A.Heyn, ibid., 1930, 28, 113; N.Cholodny, Biol. Zentr., 1927, 47, 604.1931, 34, 1411; A., 1932, 661.Auxin-B is so written in all casesSTEWART AND POLLARD. 359Occurrence in Phnts.-The rapidly growing apical tissues of rootsand shoots of plants contain relatively large accumulations of auxin ,and Went originally extracted this by standing freshly cut tipson an agar block, into which a portion of the hormone diffused.Extraction by solvents has now been adopted, auxin being separatedin the ether-soluble fraction from various plant organs.The proportion of auxin in coleoptiles decreases from the tiptowards the base 89 and, according t o observations of K. Koch,gOthe hormone is concentrated very largely in the 0.2 mm.of the apex.I n sections distant more than 3 mm. from the tip, scarcely detectableamounts are found. The growing tips of young plants have moreauxin than those of older plants 91 and in Avena the amount formedtends to decrease with rising temperature of germination. I napical tissues of seedlings, light influences the production of auxin,and in the case of Lupinus albus cited by A. E. Navez 92 approxim-ately twice as much was found in lighted seedlings as in those grownin darkness. Auxin occurs in similar proportions in the tips ofboth young and old roots of Zeu muisY93 but in a number of otherspecies examined, Cholodny (loc. cit.) was unableeto detect the hor-mone by the Avena method. Cholodny favours the view that auxinis actually formed in the root tip, but doubt on this point isexpressed by E.BiinningYg4 C. J. GorterY95 K. V. ThimannYgs andothers, who assume the translocation of the substance from aerialparts of the plant.Cholodny also records a marked decline in the activity of excisedroot tips after 5-6 hours unless an appropriate nutrient (in thiscase, gelatin) is provided. This apparent exhaustion of the hormonemay also explain the cessation of elongation of sections of Avenacoleoptiles after immersion in water for a similar period!7 Underthese conditions growth continues on further treatment with auxin.Pollen Hormone.-F. Laibach and colleagues have made an exten-sive examination of the growth-promoting substances occurring inthe pollen of certain orchids and of Hibiscus.Pollen produces thecustomary effect of auxin on Avena coleoptiles,98 causes enlargementof the gynosternium, accelerates or renews the growth of floweringLOC. cit. K. V. Thimann, J . Gen.. Physiol., 1934, 18, 23; A., 1272.Planta, 1934, 22, 190-220; A., 1272.91 H. G. van der Wey, Proc. K . Akad. Wetensch. Amsterdam, 1931, 34,a* Proc. Nat. Acad. Sci., 1933, 19, 636; A., 1933, 987.N. Cholodny, Planta, 1934, 21, 517; A., 1044.*4 Plantu, 1927, 5, 635.06 Dissert., Utrecht, 1932.87 J. Bonner, J . Gen. Phyaiol., 1933, 17, 63; A,, 1933, 1214.875; A., 1932, 201.86 L O C . cit.Ber. deut. bot. Gee., 1932,50,383 ; 1933,51,336; A., 1933,103; 1934,120360 BIOCHEMISTRY.stems and tendrils, restricts the growth of side-shoots when amppliedto cut main stems, and stimulates root production on cut stems of anumber of plants.99 The hormonal potency of pollen is very highand is retained for long periods.This is ascribed 1 to the fact thatthe substance does not occur actually in the pollen grains but in thecaudicle, the plastic nature of which affords a protective action.By incorporation of lanolin with pollen extracts Laibach producesa concentrated auxin preparation of persistent activity, whichin addition to the ordinary effect on decapitated coleoptiles iscapable of producing curvature in intact coleoptiles when paintedon one side, and a corresponding (reverse) curvature in similarlytreated aerial roots of Cissus gongyloides.Occurrence in Fungi, etc.-Auxin was isolated from cultures ofRhizopus suinus by N.Nielsen and its properties were studied byH. E. Dolk and K. V. Thimann.3 According to these authorshormone production is favoured by aeration, is influenced by thestate of purity of the peptone used in media, and is paralleled bythe formation of carotenoid colouring matter. The occurrence of thehormone is associated with the production of sporangia and isprobably concerned in the germination of spores. Nielsen alsoobtained auxin from Boletus edulis, but was unable to detect it inPsallista mrnpestri~.~ The production of active material fromAspergillus niger has been examined by P. Boy~en-Jensen,~ whoregards auxin merely as a metabolic product of the fungus and asplaying no part in its growth, Formation in the organism dependson the nature of its nitrogen nutrient.The presence of certainamino-acids of high molecular weight appears necessary. Peptoneand hzemoglobin are effective in this respect. Inorganic forms ofnitrogen are unsuitable.6 T. Sakamura and T. Yanagihara 7 confirmthe formation of auxin in media containing peptone and also sodiumnucleate, but show that alanine, asparagine, aspartic and glutamicacids are ineffective sources of nitrogen. The growth substance isproduced in a,erobic and in anaerobic cultures. I t s formationis inhibited by the presence of glucose (contrary to Boysen-Jensen’sobservation), sucrose, fructose, maltose, galactose, and glycerol,but not of mannitol or lactose.OD F. Laibach, A. Muller, and W. Schiifer, Natumuiss., 1934, 22, 588; A , ,1272.This effect is also produced by Kogl’s auxin.F. Laibach, Ber. deut. bot. Ges., 1933, 51, 386.Jahrb. wiss. Bot., 1930, 73, 125; Biochem. Z., 1931, 23, 244.Proc. Nat. Acad. Sci., 1932,18, 30, 692; A., 1932, 549; 1933, 327.Ibid., 1932, 250, 270; A., 1932, 1065.Ibid., 1931, 239, 243; A., 1931, 1334.Proc. Imp. Acad. Tokyo, 1932, 8, 397; A,. 1933, 197.* Biochem. Z., 1932, 249, 196; A., 1932, 887STEWART AND POLLARD. 361The hormonal preparation from yeast recorded by N. Nielsenalso contains auxin, which is presumably the active agent of yeastextracts concerned in stimulating the blossoming of peas.9Various species of bacterialowhen grown on peptone media produceauxin, which has also been isolated from the marine alga Valoniamrophysa, in which it is mainly concentrated in the cell walls.llOccurrence in Animal Orguns.-The distribution of auxin is notlimited to the plant kingdom.It has been found in the blood,liver, and kidneys of guinea pigs, in rabbit lungs, in pig’s thyroid,in human and mouse carcinoma, and in a wide variety of otheranimal tissues.12 Much larger proportions were obtained by Kogland colleagues l3 from urine, the source of the material used in theirinvestigations of the chemical constitution of the hormone. Urinaryexcretion of auxin seems very largely controlled by the dietaryintake and is not influenced by age, sex, pregnancy, or menstruation,or by carcinomatous or tuberculous conditions.14Geotropism, Phototropism, and Electrotropism in Plants as relatedto Auxin-A.-The relationships between the action of auxin andgeotropic and phototropic curvature in plants have provided aninteresting field of investigation.F. W. Went (Zoc. cit.) and alsoE. Seubert l5 have shown that decapitated Avena coleoptiles whenplaced horizontally can be stimulated to further growth with normalgeotropic curvature if the hormone is placed symmetrically on thestump. H. E. Dolk l6 assumed that under these conditions auxinwas translocated preferentially to the under side of the coleoptileand induced the normal upward curvature. If the auxin is placedasymmetrically on the horizontal stump, geotropic response in thenew growth is retarded or enhanced according as the auxin is applied* Biochern. Z., 1931, 236, 205; A , , 1931,1091.* A.I. Virtanen and S. von Hausen, Nature, 1933, 132, 408; 1934, 133,383 ; A., 1933, 1093 ; 1934, 463 ; V. Subrahmanyan and G. S. Sidappa, ibid.,1933, 132, 713; A., 1933, 1342.lo P. Boysen-Jenaen, Biochem. Z . , 1931 , 236, 205; A,, 1931, 1091.11 H. G. van der Weij, Proc. K . Akad. Wetensch. Amsterdam, 1933, 36,769; A , , 1934, 120.l2 E. Maschmann, Natumoiss., 1932,20, 721 : A., 1932,1156; E. Maschmannand F. Laibach, ibid., 1033,21, 517; A., 1933, 1213; F. Kogl, A. J. Haagen-Smit, and B. Tonnis, 2. physiol. Chem., 1933, 220, 162; A., 1933, 1213.13 Summaries of this work are t o be found in Angew. Chem., 1933, 46, 469;A., 1933, 987; Rep. Brit. ASSOC., 1933, 600; Naturwiss., 1933, 21, 17; A.,1933, 435.1 4 F. Kogl, A.J. Haagen-Smit, and H. Ersleben, 2. phyaiol. Chem., 1933,220, 137; A., 1934, 1213.1 5 2. Bot., 1926, 17, 49.16 Proc. I<. Akad. Wetensch. Amsterdava, 1926, 29, 1113; Dissert., Utrocht,1930.M 362 BIOCHEMISTRY.to the upper or the lower side of the st~mp.1~1 1% l9 In corre-sponding experiments with roots it has been shown that in theseorgans also geotropic response is associated with the movement ofauxin to the lower side of the tip with consequent restriction ofelongation on this side.201 21Similarly the normal phototropic response of a coleoptile which isweakened or eliminated by decapitation is restored by symmetricalplacement of auxin in agar on the stump. Asymmetrical applic-ation causes a restricted or accentuated response according asactivation is on the near or the far side of the stump with respect tolateral illumination. Similar effects are produced by removal ofone half of the coleoptile tip (Koch, Zoc.cit.). It is concluded thatin the normal coleoptile auxin tends to move towards the shadedportions of the stem.The conception of the existence of a potential gradient in theplant system, and of its variation with the rate of growth, is of longstanding. The known growth response of plants to an artificiallyapplied electric field has been shown by Dolk, Went, Cholodny(Zocc. cit.) and other workers to be explicable by the translocation ofauxin within the plant towards positive polarity. Kogl (loc. cit.)observed that the potency of his auxin preparation a.s measured bythe Avem method varied hourly, and from day to day.He finallytraced this effect to variations in the electrical condition of the atmo-sphere. Further, by passing very small currents through theagar-auxin block and the coleoptile stump on which it was placed,he demonstrated that the curvature per auxin unit could be variedat will by changing the polarity of the system, to accelerate or retardthe normal basal movement of the hormone. The acid character ofauxin indicates a tendency to migrate towards the positive pole, andKoch 22 explains the electrotropic curvature of stems towards thepositive by the impermeability of the cuticle to aqueous solutions.The cuticle acts as an insulating medium, and an externally appliedpotential difference induces a reversed polarity within the tissueitself.As a result, auxin moves toward the internal positive(i.e., towards the external negative) pole, producing curvaturetowards the external positive. The view is confirmed by insertionof needle electrodes through the cuticle directly into the tissue ;curvature towards the negative pole then occurs. Epidermal tissuesW. G. du Buy, Rec. Trau. bot. nierl., 1933, 30, 1.E. Nuernberk, Flora, 1933.lS K. Koch, Plantu, 1934, 22, 190; A., 1272.2O N. Cholodny, Ber. deut. bot. Qes., 1932, 60, 317; 1933, 61, 85,21 P. Boysen-Jensen, Plantu, 1933, 20, 688; A., 1934, 334.22 LOC. C i t STEWART AND POLLARD. 363of roots are freely permeable and no question of induction arises.Curvature is always toward the positive pole.More recent observations of K.Ramshorn 23 confirm and adddetail to earlier records of the electrical conditions obtaining inplants, and demonstrate the electropositive character of zones ofrapid growth with respect to the more slowly growing parts.Tropic movements in general, therefore, are such as to indicatemovement of the growth-promoting substance toward the positivepole, towards gravity or away from light and, in general, the effectsof artificially applied auxin are superimposed on normal tropic re-sponses.Cell Extension and Plant Metabolism in Relation to Auxin-A.-Various workers have observed that auxin stimulates cell elongationby increasing the plasticity of the walls. The mechanism by whichthis is effected would appear to be somewhat complicated.Thework of K. V. Thimann and J. Bonner 24 indicates that the action ofauxin is not on the formation of cell wall material, nor does it modifythe permeability of the wall, but is primarily directed on the proto-plasm. They also observe that the respiration of coleoptile sectionsincreases when the proportion of auxin present is small.S. Strugger 25 shows that the growth of seedling shoots of HeEianthusannuus is stimulated by immersion in acid buffer solutions and thatif a longitudinal strip of the epidermis is removed a permanentcurvature away from the wound is produced in decapitated (andsupposedly auxin-free) hypocotyls. A similar effect is induced inanaerobiosis in which the internal acidity of the cells is automaticallyincreased.Strugger suggests that auxin promotes cell elongationby regulating the course of cell metabolism to produce acid condi-tions, and in this way influences the rate of growth, which is relatedto the difference between the pH and the isoelectric point of theprotoplasm,I n a later paper J. Bonner 26 confirms the increased plasticity ofcell walls following acid treatment in the case of Avena coleoptilesand further shows that the resulting growth increase is inhibited byconcentrations of hydrogen cyanide of the same order as those whichinhibit the action of auxin. Auxin itself does not increase cellacidity. The stimulative action of acids on decapitated coleoptilesis ascribed to the conversion of inactive salts of amin remaining inthe stump into the active non-dissociated form.23 Planta, 1934, 22, 737.z4 Proc.Nut. Acad. Sci., 1933, 19, 714; A., 1933, 1093; Proc. ROY- S0C.sz 6 Ber. deut. bot. Om., 1932, 50, 77; A., 1933, 102; {bid., 1933, 51, 193.z6 Protopkssma, 1934, 21, 406; A., 1272.1933, B, 113, 126; A., 1933, 757364 BIOCHEMISTRY.The association of geotropic influence with chemical differences inplant tissues is brought out by observations of T. Warner,27W. Gundell,28 and P. Metzner.29 The undersides of horizontallyplaced shoots have a markedly increased sugar content and hydrogen-ion concentration, a small increase in catalase activity, and, in theexpressed sap, only small differences in osmotic pressure, conduc-t i ~ t y , viscosity, and surface tension as compared with the uppersides.In so far as these observations can be interpreted in relationto Strugger's views they are of a confirmatory nature.Auxin-B.Associated with auxin-A from a number of sources is anothergrowth-substance, differing from it in physiological activity butrelated to it chemically. The chemical constitution of these sub-stances is more appropriately dealt with in the Organic Chemistrysection of these Reports. Apart from physiological distinctions,it is usually sufficient in biochemical work to differentiate betweenthe two substances by the solubility in ether ( A is soluble) and byresistance to heat and oxidation (B is resistant).Auxin-B has no influence on Avem coleoptiles, but is usuallyc haracterised by accelerating the growth of Aspergillus niger.Auxin-B occurs with -A in Rhizopus suinus, in amounts which appearto be related to the pH of the medium.30 E.Biinning31 recentlyconfirmed the presence of auxin-B in A . niger and examined itsaction on the growth of the fungus. Auxin-A does not affect theweight of mycelium produced or the numbers of conidia, but causesa slightly accelerated formation of conidia and subsequent degener-ation. Auxin-B, however, produces a very marked increase inmycelium production. Both hormones favour the resorption ofnitrate from media and retard that of ammonia. The resultingtendency towards increased % in the media may explain the slightlyearlier formation of conidia in the presence of auxin-A. N. Nielsenand V.Hartelius 32 indicate that auxin-B acts on A . niger as a resultof modification of %-growth relationships as in the case ofRhizopus (above). Thus optimum growth in the presence ofa.uxin-B occurs at pH 6-7, and in its absence, at pH 3.The rate of regeneration of yeast is increased by auxin-B to anextent proportional to the amount present. The size of the27 Jahrb. wiss. Bot., 1928, 88, 431.2D Ber. deut. boi?. Ge.., 1934, 52, 506.so N. Nielsen and V. Hartehe, Compt. rend. Trav. Lab. Carlaberg, 1932,19,31 Ber. deut. bot. Ges., 1934, 52, 423.32 Compt. rend. Trav. Lab. Carlsberq, 1933, 19, No. 15; A , , 1933, 1205.28 Ibid., 1933, 78, 623.No. 8; A., 1932, 661STEWART AND POLLARD. 366individual cells is unaff eoted. Turbidity measurements of yeastcultures are suggested by E.Almoslechner 33 for the quantitativedetermination of auxin-B.reports the presence of auxin-B in maize oil and in malt.It is also found in Boletus edulis and in urine, blood, milk, and anumber of vegetables. Examination of preparations from the latterproducts shows that auxin-B, in order to exert its full activity,requires the presence of a complementary substance (" Co-B "),which is deficient in a number of the above products. Filter-paperash and zinc salts appear to fulfil this requirement.35KoglOther Growth-regulating Substances.Since Wilder first recorded the existence of a growth-regulatingsubstance, " bios," a number of hormone- or vitamin-like substancesaffecting growth in the plant world have been described. Morerecently it has been shown that animal hormones and vitamins mayalso exert a growth-promoting action on plants.Certain simil-arities in the physiological activities of these substances, or in thoseof various constituent fractions into which a number of the crudematerials have now been resolved, tend towards the view that amongplant and animal hormones and vitamins there may well exist closerfundamental relationships than are as yet apparent. This con-ception is illustrated by such investigations as that of Williams etal.36 Yeast-stimulating preparations, obtained from a wide rangeof plant and animal products, all contained a polyhydroxylic acid,panthothenic acid, very closely related to vitamin-B,. Wilder's" bios," now shown t o contain probably three constituents, inducesincreased growth in certain fungi. Auxin-A preparations fromAvena and from fungi stimulate yeast growth but do not contain the" Z "-factor regulating fermentati~n.~' T. Philipson 38 also recordsa yeast-stimulating complex in green peas. Two constituents areindicated, neither of which alone shows any activity in this respect.The growth of Nematospora gossypii, especially as related to theassimilation of nitrogen compounds, depends on the presence of agrowth factor, shown by H. W. Buston and co-workers 39, 40 to be33 Planta, 1934, 22, 515.34 F. Kogl, H. Erxleben, and A. J. Haagon-Smit, 2. phyewl. Chem., 1934,35 V. Hartelius, Biochem. Z., 1933, 261, 76, 89; A., 1933, 751.36 R. J. Williams, C. M. Lyman, G. H. Goodyear, J. H. Truesdail, and D.3 7 H. von Euler and T. Philipson, Biochem. Z., 1932,245,418; A., 1932, 550.38 Ibid., 1933, 258, 244; A., 1933, 427.39 H. W. Buston and B. N. Pramanik, Biockern. J., 1931, 25, 1656, 1671;40 H. W. Buston and S. Kasinathen, ibid., 1933, 27, 1859; A., 1934, 230.225, 215; A., 1044.Holiday, J. Amer. Chern. SOC., 1933, 55, 2912 ; A., 1933, 982.A., 1931, 1458366 BIOCHEMISTRY.a complex related to (' bios," and to contain i-inositol as a necessaryconstituent factor. Among bacteria, Micrococcus eykrnunii isstimulated by a substance occurring both in plants and in animals,which in some respects resembles but is not identical with auxin.This growth substance depends for its activity on the presence ofpeptone .41For example,W. Schoeller and H. Goebe142 have demonstrated the action offolliculin in accelerating the development and flowering of hyacinths.Apparently the hormone requires conversion into more readilyabsorbed sodium salt before becoming effective. Similar results arerecorded by M. J a n ~ t , ~ ~ who also finds that equilin, equilenin, anddihydrofolliculin are even more active. Injection of thyroidmaterial into bulbs increases the rate of flGwering and the numberof flowers produced.44 Thyreoidin stimulates the germination offungal spores, improves vegetative growth, and accelerates alcoholicfermentation by yeast, but has little influence on bacterial develop-ment.45 The action of thyroxine on plants is mainly directedtowards leaf development, whereas adrenaline and hypophysin actprincipally on roots.46More extensive examinations of the action of vitamin-B on fungiare recorded and serve to illustrate the trend of opinion towards theview that this vitamin has much in common with the typical planthormones. W. H. Schopfer4' has prepared from wheat germ,yeast, and pollen a growth substance accelerating vegetative growthand zygote formation in Phycomyces blakesleeanus, closely resemblingauxin and differing from the vitamin-B complex only in heat re-sistance and in adsorption by animal charcoal. Vitamin-B, andto a lesser extent -B, produce similar effects on the fungus, althoughin this case the action is dependent on the nature of the carbohydratesupply. E. Bunning,48 working with A . niger, shows thatvitamin-Bl has little action on growth except in alkaline media(cf. folliculin, above), whereas -B, markedly increases dry matterproduction. Like auxin-A and -B, the vitamin-B complex favoursthe absorption of nitrates by the fungus and restricts that ofL. E. den D. de Jong, Arch. Mikrobiol., 1934, 5, 1 ; A., 699.42 Biochem. Z., 1931, 240, 1; A., 1931, 1337; ibid., 1932, 251, 223; A.,1932, 1068; ibid., 1934, 272, 215; A., 1145.43 Compt. rend., 1934, 198, 1175; A., 463.44 E. E. Davies, Plant Physiol., 1934, 9, 377; A., 1272.46 A.A. Imschenetzki, Bull. Acad. Sci., U.R.S.S., 1932, 1559; A., 1933, 868.40 D. V. Hykes, Compt. rend. SOC. Biol., 1933, 113, 629; A., 1934, 934.47 Arch. Sci. phya. nat., 1934, [v], 16, Suppl., 23, 26, 29; A., 1035; Ber.Many animal hormones also influence plant growth.deut. bot. Qea., 1934, 52, 308.Ber. deut. bot. Qes., 1934, 52, 423STEWART AND POLLARD. 367ammonium. Also its action is similarly related to respiratoryactivity and to reaction changes in the media. W. G. Solheim etaZ.4Q find that vitamins-B, and -B, stimulate fructification in anumber of fungi and increase yellow pigmentation in A . niger andPenicillia. These physiological similarities among different hor-mones and vitamins are tending to intensify investigations of thechemical nature of the substances concerned, and provide anenormous stimulus to research in this fascinating branch ofbiochemistry .C. P. STEWART.A. G. POLLARD.49 W. G. Solheim, S. S . Sears, and R. C. Robbins, Phytopath., 1933, 23,929; A., 1934, 220

ISSN:0365-6217    

DOI:10.1039/AR9343100322

出版商:RSC    

年代:1934

数据来源: RSC

摘要:

RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.IN the field of nuclear physics, 1934 has been chiefly notable fortwo discoveries and for a development in theory which is not un-related to one of them. The products of artificial disintegrationwhich, hitherto, have always proved to be known or soon-to-be-discovered stable atomic species have now, in a large number ofcases, been shown to be unstable and of short life. These" artificial " radio-elements disintegrate with emission of electrons-or in some cases of positrons. They have been produced by hom-barding various substances by a-particles, neutrons, protons, anddeuterons. Interest in theories of p-disintegration has, very natur-ally, been increased by this discovery, and two fairly successfultheories have been advanced during the course of the year.Thesehave much in common as to their predictions, but show wide differ-ences regarding initial assumptions. The second discovery towhich reference has been made is of a nuclear photo-effect. It hasbeen shown that the nuclei of heavy hydrogen and beryllium maybe disintegrated by absorption of y-radiation. I n more routineinvestigations knowledge of the isotopic constitution of many ele-ments has been extended, and several examples of artificial trans-mutations, previously discovered, have been examined in greaterdetail. Increased precision has been attained in the measurementof radioactive a-particle and y-ray energies, under the incentive oftheory. The collection of data concerning the penetrating radiationhas been carried out as energetically ass before, but, a t present, nocompletely satisfactory interpretation appears to have been offered.The Isotopic Constitution of the Elements.Masses and Abundance Ratios.-Investigation of the naturallyoccurring elements by mass-spectrum analysis has been broughtone stage nearer a complete first survey by the publication of aseries of reports from F.W. Ast0n.l These deal chiefly with therare-earth elements. ,4t the same time, however, new data havebeen obtained concerning a number of others. All are included inTable I. Two entries only are derived from other sources, viz.,those concerning hydrogen and argon. For argon, P. Zeeman andNature, 1933, 132, 930; 1934, 133, 327, 684, 869; 134, 178; Proc.Roy.SOC., 1934, [ A ] , 146, 46; A., 127, 341, 713, 825, 937, 1150FEATHER. 369J. de Gier conclude from positive-ray analysis that A38 is presentin appreciable amount ; the detection of H3 in naturally occurringhydrogen is the work of W. W. Lozier, P. T. Smith, and W.Bleakne~.~ The new isotope of helium, He3 (see below), is notincluded, since itordinary helium.At.Element. no.HydrogenArgonCalciumTitaniumNickelZirconiumRhodiumCadmiumLanthanumCeriumPraseodymiumNeodymium11820222840454857585960has not as yet been foundTABLE I.Massnos.1*2*336*3840*40*424344*464748*49505658”60*61626490*9192 *94*961031061081 lo*Ill*112*113*114*115ll6*139*140142141*142Percent.abund-ance.99.990.01< 10-7 -96.70.80.22.3ffffv.f.S----v.f. ------ --- --..--..---891136-Element.NeodymiumSamariumEuropiumGadoliniumTerbiumDysprosiumHolmiumErbiumThuliumYttriumLu t eciumHafniumThoriumin any anallpis ofAt.no.60626364656667686970717290Massnos.143144145146144147148149150152154151153155156157158160159161162163164165166167168170169171172173174176175176177178179180232Percent.abund-ance.113051831714155262050.649.421231723162225252836243010924173812f----SSSS -* Indicates a previously-known isotope.Considered in conjunction with Appendix I1 of F.W. Aston’s“Mass Spectra and Isotopes” (London, 1933), Table I gives the2 Proc. K . Akad. Wetensch. Amsterdam, 1934, 37, 127 ; A., 578.3 Physical Rev., 1934, [ii], 45, 655370 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.present state of knowledge of the isotopic constitution of theelements?In the range of mass numbers 1 to 210, only eight are not withcertainty allotted to any element, zfix., 5, 8, 67, 105, 191, 193, 194,195. However, analyses of palladium, iridium, platinum, and goldhave so far not been effected. When data are available for theseelements, it is unlikely that more than four of these gaps willremain.In Table I1 the values of atomic weights calculated from massesand abundance ratios, for the rare-earth elements, are comparedTable 11.Atomic weight frommass- internationalElement. spectrum.table.La 138.91 f0.05 138.92Ce 140.13&0*05 140.13Pr 140.91 50.05 140.92Nd 143.5 f 0 - 2 144.27Sm 150.1 f0.2 150.43EU 151*90&0.03 152.0Gd 156.9 h 0 . 2 157.3r >Atomic weight frommass- internationalElement. spectrum. table.Tb 158.91 f0.05 159.2Dy 162.5 f 0 . 2 162.46HO 164.91 f0.05 163.5Er 167.16f0.2 167.64Tm 168.91fO-05 169.4Yt 173.2 f0.2 173.04LU 174-91 f0.05 175.0.A f 1with the values given in " International Atomic Weights," 1934.The chief discrepancies occur with neodymium and holmium.The calculations from mass-spectrum data are made on the assump-tion that packing fractions vary regularly from - 5 x 10-4 to- 3 x 10-4 from the beginning to the end of the rare-earth series.The atomic weight of erbium has recently been determined by0.Honigschmid and W. Kapfenberger as 165.20. This standsin violent disagreement with the mass-spectrum value and theaccepted chemical value. In spite of the apparent consistency of thenew chemical analyses, therefore, the Committee of Atomic Weightsof the International Union of Chemistry has not a t present adoptedthe lower figure. Eight changes have been made, however, and ofthese, three, Se 79.2 to 78-96, Te 127-5 to 127.61, Cs 132.81 to 132.91,'materially improve the agreement with mass-spectrum values(Se 78.96, Te 127.58, Cs 132~92).~The abundance ratio 0l6 : 0 l 8 has been redetermined twice duringthe period under review.W. R. Smythe? preparing the gas byA comprehensive survey of methods and results has also been given byJ. Mattauch, Phpikal. 2.. 1934.35, 567; A., 937.2. anorg. Chem., 1933,214, 97; A , , 1933, 1099.J., 1934, 499; A,, 713.G. P. Baxter and J. S. Thomas, J . Amer. Chern. SOC., 1934, 56, 1108;A., 713.* See this vol., p. 94, for discussion of certain other atomic weights.Physical Rev., 1934, [ii], 45, 299; A., 469FEATHER. 37 1decomposition of lead dioxide, reports 503 & 10, D. I. Eropkinand V. N. Kondrateev,lo from atmospheric absorption spectra, haveobtained 595. The best value of the Naude correction factor 11remains, therefore, about 1.0002.W. R. Smythe has suggestedreasons why his value for the isotopic ratio might be expected todiffer from the normal, but these do not appear to be substantiatedby the work of H. S. Taylor and A. J. Gould,12 who consider themost trustworthy value at present to be 514 & 13 (see further,this vol., p. 98).Abundance ratios for other light elements have also been re-determined. From intensity measurements on the lithium resonanceline, L. S. Ornstein, J. A. Vreeswijk, jun., and G. Wolfsohn13obtain Li : Li = 8-1 r f I 0.4, in agreement with previous opticaldeterminations,14 but new mass-spectrograph experiments of A. K.Brewer and P. D. Kueck l5 lead to the ratio 12.14 & 0.4 : 1, sub-stantially confirming all earlier estimates by this more direct method.16The latter authors have also determined the ratios K39 : K41 andRbs5 : Rb87, obtaining 13.9 & 0.4 and 2.59 0.04, respectively.Earlier measurements of A.J. Dempster l7 and F. W. Aston l8indicate 18 : 1 and 3.0 : 1 for these two elements.lgThe results of W. W. Lozier, P. T. Smith, and W. Bleakney3 forH I : H3 are included in Table I. The same workers with G. P.Harnwell and H. D. Smyth 20 are also responsible for the negativedata concerning He3 and He5, to which reference has already beenmade. They find He4 : He3 > 105, He4 : He5 > lo6 for naturallyoqcurring helium. Preliminary reports concerning carbon, nitrogen,neon, and argon are due to A. L. Vaughan, J. H. Williams, andJ. T.Tate; 21 their values, obtained by mass analysis, areC12 : C13 = 91.6 & 2.2, NI4 : W5 = 265 & 8, Ne20 : Ne21 = 337 &20, Ne20 : Ne22 = 9.25 & 0.08, and A40 : A36 = 304 & 12. F. W.Aston 22 has obtained 140 & 14 for C12 : C13. The previouslyl o Compt. rend. Acad. Sci. U.R.S'.S., 1934,1,445; A., 580.l1 Ann. Reports, 1932, 29, 305.l2 J . Amer. Chem. SOC., 1934, 56, 1823; A., 1082; see also R. Klar andA. Krauss, Naturwiss., 1934, 22, 119; A., 377.l3 Physka, 1933, 1, 53; A,, 127.14 Ann. Reports, 1932,29, 304.15 Physical Rev., 1934, [ii], 46, 894.1 7 Physical Rev., 1922, [ii], 20, 631; A., 1923, ii, 413.18 Proc. Roy. SOC., 1932, [A], 134,.571; A., 1932, 209.19 A curve given by W. R. Smythe, L. H. Rumbaugh, and S. S. West(Physical Rev., 1934, [ii], 45, 724; A., 860) appears to favour the value ofBrewer and Kueck against that of Dempster.l6 Ann.Reports, 1933, 30, 348.20 Physical Rev., 1934, [ii], 46, 81.21 Ibid., p. 327. 22 Nature, 1934, 134, 178; A., 937372 RADIOACTIVITY AND SUB- ATOMIC PHENOMENA.accepted ratio was 106 : 1.23 For nitrogen the ratio 265 : 1 is,again, much lower than the last recognised value, about 330 : 1,itself only one-half the original estimates. The relative abundanceof Ne 22 appears to be a little greater, and that of Ne 21 considerablysmaller, than was previously believed. The argon determination, onthe other hand, is the first of any reliability; it gives A36 a lowerabundance than has sometimes been supposed.The position regarding the magneto-optic method of analysis 24has become somewhat clearer during the year.J. Papish andA. C. Shuman25 have had the opportunity of testing the apparatusused in the Alabama Polytechnic Institute. Their report is entirelyunfavourable. Similarly, comparison of F. W. Aston’s work oncalcium 26 with that of F. Allison and R. Goslin 27 is sufficient com-ment on the great sensitivity which these authors claim for theirmethod. (Prau) I. Noddack28 has also made a critical survey ofthe evidence in favour of the existence of new elements recentlyreported as discovered; the conclusion is against the presentidentification of elements of atomic number 61, 85, and 87.Mechanical and Magnetic Moments of Nuclei.-In addition tothe two scalar quantities, mass and electric charge, two vectorquantities are required in order to describe in detail the interactionbetween the nucleus of an atom and its extranuclear electrons.These two quantities are the mechanical and the magnetic momentof the nucleus.As is the case with the scalar quantities, the magni-tude of one of these vectors is restricted to integral multiples ofthe fundamental unit for all nuclei, whilst that of the other is notso restricted. The mechanical moment (total angular momentum)of any nucleus is integral in terms of h/4n, h being Planck’s constant.Hitherto, experiments in this field of nuclear research have notbeen reported upon in the present series of reports,29 but the body oftrustworthy data is now so large, and the methods of attack alreadyof such variety, that some reference must be made to them and tothe results. The latter have been collected from time t o time inrecent years,a but much new material has accumulated since thelatest of these surveys.23 Ann. Reports, 1933, 30, 348.25 Science, 1934, 79, 297 ; A,, 625.2 7 PhgskaZ Rev., 1932, [ii], 40, 1015; A., 1933, 1223.28 Angew.Claem., 1934, 47, 301 ; A., 853.p9 See, however, Ann. Reports, 1932, 29, 17; 1933,30, 76 et seq.30 H . Kallmann and H. Schuler, Ergeb. exakt. Naturwiss., 1932, 11, 134;G. Beck, Marx, “ Handbuch der Radiologie,” VI, (l), 1933, 279; N. F. Mott,“ Handbuch der Physik,” XXIV, ( l ) , 1933, 785 ; F. W. Aston, “ Mass Spectraand Isotopes,” 1933, chaps. 15, 16; H. Schuler, 2. Pkysik, 1934, 88, 323;A., 580.24 Ibid., p .349.Nature, 1934, 133, 684; A., 713FEATHER. 373Until recently,31 only two experimental methods were available.By measurement of the alternating intensities of the lines formingthe rotational structure of the band spectrum of an elementarydiatomic molecule, it is possible to calculate the value of themechanical moment ( I ) of the nucleus concerned. However, thedifference in intensity between neighbouring lines is small when themechanical moment is at all considerable, and it is with only a fewelements that diatomic molecules are formed which give rise toband spectra suitable for investigation. The second method in-volves the examination of the hyperfine structure of atomic spectrallines. Then, so long as the margnetic moment (p) is not too small,I may be deduced unambiguously from the complexity of the hyper-fine structure of certain lines, though a knowledge of the corre-sponding structure of other lines in the same spectrum may yield nodefinite information on this point.In favourable circumstances itis possible to calculate p from measurements on the hyperfinestructure separation^.^^ The underlying theory, however, isintricate and an accuracy of a few units :/o is all that can be claimedin most cases. Quite recently, however, two other methods, ofpossibly more general applicability, have been successfully developed.They may be referred to as the methods of polarised resonanceradiation and of atomic beams. The former method was appliedto the sodium-D resonance radiation by N.P. Heydenburg, L.Larrick, and A. Ellett,33 who measured the percentage polarisationfor plane-polarised exciting radiation and zero magnetic field.It was hoped that measurements in these conditions would enableI to be evaluated, whilst similar obscrvat<ions with non-zero fieldsmight lead to an estimate of p. At first, the method yieldedunacceptable results, but now, after more precise consideration ofthe underlying theory,% the discrepancies have been removed.The method appears to be chiefly useful for the evaluation of pwhen I is known. The small differences in form of the ideal polzr-isation-magnetic field curves for different I values do not a t presentappear decisive enough for use in determining I , since many depar-tures from ideal simplicity frequently characterise the experimentalconditions.The method of atomic beams has very direct affinities with thehyperfine structure method of investigation.Thus I may bedetermined, if [L is not too small, merely by counting the number of31 See W. E. Curtis, Nature, 1934, 133, 256; A . , 340.32 E. Formi and E. Segri?, 2. Physilc, 1933, 82, 729; A., 1933, 769; H e m .33 Physica2 Rev., 1932, [ii], 40, 1041; A., 1933, 1220.34 See G. Broit, Rev. Mod. PhYSiCS, 1933, 5, 91 (VII, $4).R. A d . d’Italia Sci. Jis., 1933, 4, 131; A., 331374 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.lines in a deflexion pattern, whilst, for the calculation of p fromobserved separations, the same detailed information is required as isneeded for the similar calculation from hyperfine-structure data.There is one difference, however : the axis of the magnetic momentof the nucleus may be in the same direction as that of the mechan-ical moment, or in the opposite direction (negative magneticmoment). This ambiguity of sign may be settled from observationson the hyperfine-structure pattern, but it remains unresolved whenp is obtained by the method of atomic beams.The suggestion thatthe arrangement of W. Gerlach and 0. Stern might be modified forthe purpose of determining I-and so p-was put forward first byG. Breit and I. I. Rabi.35 This is the method which has just beendescribed. It differs in essentials from another molecular-beammethod applied by 0. Stern and his collaborators 3i3 to the determin-ation of the magnetic moments of the nuclei H1 and H2.In thismethod, the nuclear moment is obtained when the effective magneticmoment of the molecule has been corrected for the rotationalcomponent. This correction was directly made in the case ofhydrogen by making observations with ortho- and para-hydrogenin turn. The results, however, again are ambiguous with regard tosign.The data of Table I11 refer chiefly to atomic species of odd massnumber. Those of even mass number, with theTABLE 111."I .r-------- Nuclear species. B. H. 0.nl -H1 4H2 ............... 1He4 ............... 0Li7 ............... + Be@ -C'B ............... 0N14 ............... 1Of6 ............... 0FlS $Na23 ............2- Mg -~ 1 2 7 -P31 ...............a 3 5 .............................. ............................................................ ...............532 ............... tK30 ............... >:sc45 - ...............exception ofReferences.36, 4236, 42, 434445464748, 49, 50, 51525354,5556, 57----- -as Physical Rev., 1931, [ii], 38, 2082.38 R. Frisch and 0. Stern, 2. Physik, 1933, 85, 4; I. Estermann and 0.Stern, ibid., p. 17; 86, 132; Nature, 1934, 133, 911; A., 1933, 996, 1226;1934, 828Nuclear species.V5'MnS5 ,...........c059 . . .. . . . . . . . .Cu63cussZns7 ............Gaa9 ............Ga71 ...............As75 ............Br79 . . . . . . . . . . . .see0 . .. . . * . . . . 0 .. . .Brel . , . , . . . .. . . .Kra3 . . .. . . . . . . . .Rbes ............Rbe7 .... . . . .. . . .Sre7 ........... ,. ..N b 9 3 ....... . . ..... *M o ~ . . . . . . . . . . . .Mog7 ............Aglo7 ............Aglo9 . .. . . . . . . , . .Cdlll ..... . , .. . . .Cd113 ............Snlf7 .... ..... ...Sn1lg ... . .. ......Sb121 .... . ...... .Sb123 ... . . .. . . . . .1127 .. .... . . . . . . , . .Xe129 . . . . . . . . . . . .Xe'31c s * 3 3 . . . . . . , . , . . .Ba13' ............La139 ............Pr141 , . . . . . . . .. . .TblS9 ............Tmlss ............Lu175Taler ..... . . . .. . .W'83Rela5 ............~ 8 1 3 7 ............A11197 .. . . ... , . . . .Hgle9 . . . . . . . , . .. .Hg201 . . . . . . . . . . . .Pb207 ............Bi2O0 . . . . . . . . . . . .Pa231 ................ . . . . . . . . . . .. . . . . . .... . . . . . . . . . . . . . .1 ~ 1 1 5 . . . . . . . . . . . .. .. . . . . . . . . ..... , ,. . .. . ........ . . . . .~ 1 2 0 3 . . , . . . . . . . . .~ 1 2 0 5 . . . . . . . . . . . . . . .FEATHER.TABLE 111."-Continued.r.Afl.--2-32.72.72.12.70.9-I -----( - 0.9)3.7 --< 0.3<Om3- 0.6- 0.65.3- 0.9 - 0.92.79.1 -375References.58, 5960, 61---62 -1163646565-6667675252 --6869697071-72,7372, 732.7 74-70* The values of I are given in units of h/%, those of p in protonic mag-netons, i.e., in terms of eh/4vMc.B, H, and 0 refer, respectively, to deter-minations from band spectra, hyperfine structure, and other methods. Refer-ences are given where they are not included in one of the surveys alreadyquoted376 RADIOACTIVITY AND SUB- ATOMIC PHENOMENA.H2, Li6, B1O, and N14, have even atomic number also, and it hasgenerally been assumed that such nuclei (having both atomic andmass numbers even) are without mechanical moment. The dataavailable concerning the lighter nuclei confirm this hypothesis,yet it must be admitted that, for the heavier species, it remainspure assumption. The experimental facts are that it has alwaysbeen possible, hit herto, to interpret hyperfine-structure patternsin complex atomic spectra on the assumption that the true hyperfinestructure (as distinct from any structure due to isotope displacement)was to be ascribed entirely to the emission from amtoms for whichthe mass number was odd.Whatever may be the final conclusion,a t present no data exist which run contrary to this assumption.37Of the data contained in Table 111, the most unexpected, and atthe same time the most important for developing a theory of thenucleus, are the values of the nuclear magnetic moments for thetwo more abundant isotopes of hydrogen. The magnetic momentof the proton is not, as was anticipated, one protonic magneton.Concerning the relative values for the hydrogen isotopes, thereis strong con6rmatory evidence from the experiments of A. Farkas,L. Farkas, and P. Harteck3* on the rate of reconversion of ortho-hydrogen into normal hydrogen by (paramagnetic) molecularoxygen. This rate is 16 times greater for Hi than it is for H;.From this result, F.Kalckar and E. Teller 39 conclude that the ratioof the nuclear magnetic moments is 4 : 1, in good agreement withthe direct determinations.As has been indicated, the analysis and interpretation of hyper-fine structure patterns are in terms of '' magnetic splitting '' of theatomic energy levels, for a single type of atom, complicated, incases where two or more isotopes are present, by " isotope displace-ment '' of corresponding energy levels as between atoms of the differ-ent isotopic species. Regularities in this displacement structurewhere several isotopes are present have been noted, a generalbasis of interpretation having been advanced by G.Breit.40 Therelative stabilities (mass-defects) of two nuclear species appearto be important in determining the isotope displacement. Thus,in general, the difference in respect of stability between species ofodd and even ma85 iiumber shows up in the displacement pattern.3' G. Gamow (Proc. Roy. SOC., 1934, [ A ] , 146, 217; A., 1152) suggeata,in an interpretation of the data concerning radioactive /?-disintegrations,that Pb208 has a nuclear spin of 1 unit. M. Coldhaber (PTOC. Camb. Phil.SOC., 1934, 30, 561) has assigned a similar value t o Lis from a considerationof the relative probabilities of certain cases of artificial disintegration.38 Proc. Roy. SOC., 1934, [ A ] , 144, 481; A., 608.89 Nature, 1934, 134, 180; A., 940.PihysiCaZ Rev., 1934, [ii], 46, 319FEATHER. 377Here the recent observations of H. Schiiler and T. Schmidt *l onsamarium are of considerable interest. These authors find a large41 2. Physik, 1934, 92, 148.42 I. I. Rabi, J. M. B. Kellogg, and J. R. Zacharias, Physical Rev., 1934,43 G. M. Murphy and (Miss) H. Johnston, ibid., p. 95; A., 1051.44 N. M. Gray, ibid., 1933, [ii], 44, 570; A., 1933, 1219.4 5 A. E. Parker, ibid., 43, 1035.46 R. F. Bacher, ibid., p. 1001; A., 1933, 767.47 J. S. Campbell, 2. Physik, 1933, 84, 393; A., 1933, 991.4 8 J. Joffe, Physical Rev., 1934, [ii], 45, 468; A., 575.49 L. P. Granath and C. M. van Atta, ibid., 1933, [ii], 44, 935; A., 124.50 L.Larrick, ibid., 1934, [ii], 46, 581 ; A. Ellett and N. P. Heydenburg, ibid.,51 I. I. Rabi and V. W. Cohen, ibid., p. 707.52 S. Frisch and V. A. Matveev, Comnpt. rend. Acad. Sci. U.R.S.S., 1934,63 (Miss) M. F. Ashley, Physical Rev., 1933, [ii], 44, 919; A., 124.54 S. Millman, M. Fox, and I. I. Rabi, ibid., 1934, [ii], 46, 320.55 D. A. Jackson and H. Kuhn, Nature, 1934,134, 25.66 H. Kopfermann and E. Rasmussen, 2. Physik, 1934, 92, 82.5 7 H. Schuler and T. Schmidt, Naturwiss., 1934, 22, 758.5 8 H. E. White, Physical Rev., 1932, [ii], 40, 1041 ; A., 1933, 1221.5B H. Kopfermann and E. Rasmussen, Naturwiss., 1934, 22, 418.6o K. R. More, Physical Rev., 1934, [ii], 46, 470.61 H. Kopfermann and E. Rasmussen, Naturwiss., 1934, 22, 291.62 H. Schuler and H.Westmeyer, 2. Physik, 1933, 81, 665; A., 1933, 547.63 E. Olsson, ibid., 1934, 90, 138; A., 1051.64 H. Kopfermann and N. Wieth-Knudsen, ibid., 1933, 85, 353; A., 1933,6 5 D. A. Jackson, ibid., 88, 131; A., 1933, 1221.66 S. S. Ballard, Physical Rev., 1934, [ii], 46, 806.6 7 N. S. Grace and K. R. More, ibicl., 45, 166; A., 339.68 F. Paschen and J. S. Campbell, Naturwiss., 1934, 22, 136; A., 467.S. Tolansky, Proc. Roy. SOC., 1934, [A], 144, 574; A., 823.70 Idem, ibid., 146, 182; A., 1147.71 Idem, Nature, 1934, 134, 851.72 E. G. Jones,ibid., 1933, 132, 781; A., 1934, 2; Proc. Roy. SOC., 1934,73 H. Kopfermann and E. Rindal, 2. Physik, 1934,87, 460; A., 339.74 D. A. Jackson, Proc. Roy. SOC., 1934, [A], 143, 455; A., 232.75 V. W. Cohen, Physical Rev., 1934, [ii], 46, 713.76 N.P. Heydenburg, ibid., p. 802.77 L. P. Granath and R. K. Stranathan, ibid., p. 317.7 e D. A. Jackson, Proc. Roy. SOC., 1934, [A], 147, 500.70 0. E. Anderson, Physical Rev., 1934, [ii], 45, 685; A., 824.80 Idem, ibid., 46, 473.81 H. Schuler and H. Gollnow, Nuturwiss., 1934, 22, 730.82 H. Schuler and T. Schmidt, ibid., p. 838.84 J. H. Gisolf and P. Zeeman, Nature, 1933, 132, 566; A., 1933, 1219.85 L. A. Wills, PhysicaE Rev., 1934, [ii], 45, 883; A., 940.8 6 H. Schulsr and H. Gollnow, Natumuiss., 1934, 22, 511 ; A., 937.[ii], 46, 157, 163; A., 1153.p. 583.1, 460; A., 576.1095.[A], 144, 587; A., 823.e3 Idem, ibid., p. 714378 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.anomaly in the displacements amongst the isotopes of even massnumber.It seems that a change of nuclear structure sets in betweenSmlw and S11115~, most likely with a decrease in stability a t someintermediate stage. They suggest, therefore, that the a-particleactivity of samarium is to be ascribed to Sm151, present in verysmall amount, or to Sm152. They make the suggestion that thecc-activity of samarium, the p-activity of neodymium, and theextreme scarceness of element 61 upon the earth might notbe disconnected facts. A single transformation chain,B B Sm151 -% Nd147 -+ 11147 -+ Sm147, for example, would suffice tocorrelate these observations.The Separation of Isotopes.-In addition to the many physico-chemical and chemical methods developed primarily for the con-centration of the heavier isotopes of hydrogen 87 (nearly 50 paperson this subject are represented in the Abstracts for 1933), twosuccessful attempts have been made a t separation by purely physicalI n effect, these methods employ mass analysis bysome combination of electric and magnetic fields, the design of theapparatus being such that very intense ion beams may be passed.Up to the present, however, separation has been effected only withlithium and potassium.G. Hertz 89 has applied his diffusionmethod 90 to the production of spectroscopically pure H2 and,recently, with an enhrged apparat~s,~l has obtained NeZ2 verynearly free from the other isotopes of neon.Natural Radioactivity of the Lighter Elements.Potassium and Rubidium.-The occurrence of these medium-heavy, @-active nuclei of long life has hitherto presented an unsolvedproblem.Now, in the light of a fairly successful theory of p-disintegration (see below) and rapidly increasing knowledge ofartificially produced radioactive species of rapid decay, this problemcan be considered in its true perspective. G. Gamow 92 has indicatedthree possible solutions. There may be simultaneous emission oftwo @-particles (e.g., K 4 1 4 Sc41 + Ze), or the long period ma.ybe that of a preceding a-particle change (e.g., K4o --+ CP6 +He4-+ A36 + He4 + e), or the mechanical moments of initialand final nuclei (e.g., K41 and Ca41) may differ considerably.See Ann. Reports, 1932, 29, 302.M. L. E. Oliphant, E. S. Shire, and B. M. Crowther, Nature, 1934, 133,Naturwiss., 1933, 21, 884; A., 156.Ann.Reports, 1932, 29, 303.377; A., 343; Proc. Roy. SOC., 1934, [ A ] , 146, 922.91 H. Harmsen, G. Hertz, and W. Schutze, 2. Physik, 1934, 90, 703; A.,1185. 9a Nature, 1934, 133, 744; A., 714FEATHER. 379G. von Hevesy, M. Pahl, and R. Hosemann 93 have tested certain ofthese possibilities. They find evidence of two groups of electrons(though not in equal numbers)-as did D. Bocciarelli 94-b~t thereare no a-particles. No short-lived bromine isotope is formed fromrubidium, nor short-lived calcium isotope from potassium. Isotopicfractionation of potassium merely proves that K39 is inactive.F. W. Aston 95 finds no appreciable Ca41 in old potassium-richbiotites. The problem has been defined but not solved.Samarium.-The report of M.Miicier 96 of the emission of radiationof two types, a-particles of range 1.16 em. of standard air and protonsof range 1.37 cm., has not been confirmed. G. Ortner and J.Schintlmeister 97 failed to find any indication of t h e second type ofradiation. They estimate a range of 1.16 crn. of air at S.T.P. forthe a-particles. A somewhat higher value has been obtained byH. Herszfinkiel and A. Wroncberg 98 (1.67 em.), but W. F. Libby 99is in favour of the lower value (1.23 cm.). The activity determinedby G. von Hevesy and M. Pahl (75 a-particles per g. per sec.) isapproximately confirmed by the work of H. Herszfinkiel andA. Wr0ncberg,~8 although an activity almost twice as great isreported by W. F. The total activity as measured byM.Mader 96 is of the same high order.Neodymium and Other Rare-earth Elements.-By repeated fraction-ation of a rare-earth mixture, L. Rolla and L. Mazza conclude thatthe feeble activity often associated with neodymium is probably notspecific. G . von Hevesy and M. Pah13 draw similar conclusionsfrom very similar experiments : the activity of samarium is muchgreater than that of any other rare-earth element.however, believes that a thick-layer activity about one-tenth ofthat of samarium (estimated as number of disintegrations per sec.)is specific to neodymium. He considers that this is a 8-particleactivity, magnetic-deflection and absorption measurements bothsuggesting an energy of about lo4 electron-volts for the electrons.A half-value period of about 10l2 years is suggested.The thick-layer activities of praseodymium and gadolinium are a t least twentytimes smaller.Beryllium.-Following the report of R. M. Langer and R. W.93 Nature, 1934, 134, 377; A., 1150.94 Atti R. Accad. Lincei, 1933, [vi], 17, 830; A., 1933, 995.g5 Nature, 1934, 133, 869; A., 825.96 2. Physik, 1934, 88, 601; A., 713.98 Cornpt. rend., 1934, 199, 133; A., 1053.9* Physical Rev., 1934, [ii], 46, 196; A., 1150.1 Ann. Reports, 1933, 30, 344.3 Atti R. Accad. Lincei, 1933, [vi], 18, 472; A., 578.3 8. physiknl. Chem., 1934, 169, 147; A., 937.W. I?.97 Ibid., 90, 698; A., 1150380 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.Raitt of an a-activity from beryllium (half-value period - 1014years), various workers have attempted to confirm these observationsbut failed to do If a-particles of range greater than 1 cm.areemitted, then the half-value period must be greater than 1015years; if the particles have a range of 1 mm., then the minimumallowable period is lO1* years. However, on any reasonable assump-tion, unless a-particles are emitted with much less than 2 x lo4e.v. energy (0.4 mm. range), the period should be of the order ofseconds rather than millenniums. The extensive observations of(Lord) Rayleigh on the helium content of beryl,6 indicating a definitecorrelation between amount of helium and mineral age, appeartherefore as more conclusive evidence for the a-activity of berylliumthan the other experiments are to the contrary.Ascribing theactivity to Be9, and calculating from the maximum heliumcontent observed, a half-value period of the order of 10l2 years isobtained, though to assume Be8 and z - lo9 years would doequally well. It seems unlikely that the discovery of the photo-disintegration of Re9 (see below) will seriously affect the intler-pretation of these results.Zinc.-H. Fesefeldt has shown that any a-emission from zinccannot be greater than ons-tenth of that reported by H. Ziegert.8u-Activities cf Unknown Origin.-G. Dieck9 and A. V. Grosse l ohave reported such a-activities, the former from surfaces of copperand gold, and the latter from the mineral eudyalite, associated withthe actinium-containing samples in chemical analysis.Radioactivity of the Heavy Elements : New Data.No details concerning this branch of the subject were given inthe last report.Now, after a period of relative inactivity, it isprobable that the experimental attack will be renewed in certaindirections owing to the interest aroused by the new theories ofp-decay and the possibility of assigning quantum specifications tothe nuclear-excited states which result in y-ray emission. Thetheories of p-disintegration will be described in another place ;here we are concerned chiefly with the new experimental dataPhysical Rev., 1933, [ii], 43, 585.(Lord) Rayleigh, Nature, 1933,'131, 734; A., 1933, 692; R. D. Evansand M. C. Henderson, Physical Rev., 1933, [ii], 44, 59; D. M. Gans, W. D.Harkins, and H. W. Newson, ibid., p.310.Proc. Roy. Soc., 1933, [A], 142, 370; A., 1934, 53.2. Physik, 1933, 86, 611 ; A., 127.Ibid., 1928, 46, 668; A., 1928, 455.Naturwiss., 1933, 21, 896; A,, 127.lo J . Amer. Chern. SOC., 1934, 56, 1922; A,, 1160FEATHER. 381which have been collected in the two years which have passed sincethe last report.llRedeterminations of half -value periods have been made asfollows: for uranium-I, F. Western and A. E. h a r k 13, obtain(4.58 & 0.09) x lo9 years, in good agreement with the value foundby A. F. Kovarik and N. I. Adams; l3 0. ,4. Gratias l4 reports1.70 x 105 years for uranium-11, pointing out the source of error inC. H. Collie’s 15 recent determination; J. C. Jacobsen,16 havingmet the criticism directed against his earlier methods, gives3 x 10-4 sec.as the most probable value for radium-C’ ; 22.3 & 0.04years is reported by E. Walling l7 for radium-D; the value foractinouranium, according to F. Western and A. E. Ruark,l* isroughly 4 x lo8 years, and to thorium a half-value period of1.3 x 1O1O years is assigned.lgConsiderable progress has been made in the period under reviewwith the magnetic-velocity analysis of the a-particle emission froma large number of substances. The first application to this problemof the semicircular focusing method dates from 1929. S.Rosenblum 20 employed the large general-purposes electromagnetof the Paris Academy of Sciences, with photographic registration.A special-purpose electromagnet, designed by J. D. Cockcroft 21for use with electrical counting systems, was installed in theCavendish Laboratory in 1932.It has been employed by (Lord)Rutherford, C. E. Wynn-Williams, W. B. Lewis, and B. V. Bowden,22Rutherford, Lewis, and B ~ w d e n , ~ ~ and Lewis and BowdenM forinvestigations of the “ normal ” and “ long-range ” or-particleemission of the chief members of the radium and thorium series. Inthe last of their publications 24 are collected the complete resultsto date, together with the data of S. Rosenblum (concerning membersof the actinium series also), and the best values of mean ranges instandard air as previously determined .* High- a ccuracy deter -l1 Ann. Reports, 1932, 29, 308.l2 Physical Rev., 1933, [ii], 44, 675; A., 1933, 1224.l3 Ibid., 1932, [ii], 40, 718; A., 1932, 790.Phil.Mag., 1934, [vii], 17, 491 ; A., 343.l5 Proc. Roy. Soc., 1931, [A], 131, 541; A., 1931, 891.l6 Nature, 1934, 133, 565; A., 578.l7 2. Physik, 1934, 87, 603; A., 343.la Physical Rev., 1934, [ii], 45, 628; A., 713.2o Compt. rend., 1929, 188, 1401 ; A., 1929, 738.n1 J . Sci. Instr., 1933, 10, 71; A., 1933, 3G7.22 Proc. Roy. SOC., 1933, [ A ] , 139, 617; A . , 1933, 443.23 Ibid., 142, 347; A., 1933, 1224.24 Ibid., 1934, [A], 145, 235; A., 938.25 Ann. Reports, 1932, 29, 309.H. Fesefeldt, 2. Physik, 1933, 86, 605; A., 127382 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.minations of the relative velocities of the a-particles from radon,radium-A, and radium-C’ have also been made, using the directdeviation method, by G. H. Briggs,26 in continuation of earlierwork.Some evidence for the emission of long-range a-particles byactinium-C’ (roughly 9 in 105 normal a-particles from actinium-C’)has been obtained by (Mme.) P. Curie and (Mlle.) W. A. L u ~ . ~ ’R. Naidu 28 has established the ionisation-distance (Bragg) curvesfor polonium a-particles in the five rare gases, and G. Man029 thevelocity-distance curves for the a-particles of thorium-C’ traversingair, hydrogen, helium, neon, and argon. New and quantitative in-vestigations on pleochroic haloes (due to the action of a-particles,from radioactive inclusions, on mica) have been reported byG. H. Henderson with S. Bateson 30 and with L. G. T ~ r n b u l l . ~ ~Fresh information concerning primary p-particle emission dealschiefly with the upper limits of energy in the continuous spectra.B.W. Sargent 32 carried out the determination of the upper limitfor the F-particles of uranium-X, and reviewed all the data availablea t the time. He put forward very strong evidence for the realityof a close connexion, analogous to the Geiger-Nuttall relation,between disintegration constant and maximum p-particle energy.On plotting logarithms of these two quantities, it appeared thateleven points out of twelve (one for each @-active body considered)lay on one or other of two smooth curves. This demonstrationproved to be one of the starting points of the recent theories of the@-particle disintegration.Isolated investigations into the 7-radiation from certain elementshave been made by all the standard methods, crystal diffraction,%absorption,% and measurement of the heating effect ,35 in additionto those made by the method of the natural p-ray spectrum.Interestchiefiy centres in the latter measurements, however. C . D. Ellis 36has reinvestigated completely the natural @-ray spectra of the B26 Proc. Roy. SOC., 1934, [A], 143, 604; A., 342.37 J . Phys. Radium, 1933, [vii], 4, 513; A . , 1933, 1223.28 Ibid., 1934, [vii], 5, 343; A4., 1053; Ann. Physique, 1934, [xi], 1, 72;20 Ibid., p. 407; A., 579.30 Proc. Roy. Soc., 1934, [A], 145, 563; A., 1087.31 Ibid., p. 582 ; A., 1087.32 Ibi&., 1933, [A], 139, 659; A., 1933, 443.33 M. J. N. Valadares, Ann. Physique, 1934, [xi], 2, 197; A., 1151.34 (Mme.) P.Curie and P. Savel, J . Phys. Radium, 1933, [vii], 4, 457;I. Zlotowski, Compt. rend., 1934, 199, 284; A., 988.A., 235.A , , 1933, 1224; E. Stahel and W. Johner, ibid., 1934, [vii], 5, 97; A., 579.36 Proc. Roy. SOC., 1932, [A], 138, 318; A,, 1933, 4; ibid., 1934, [A], 143,350 ; A., 235FEATHER. 383and C products in the radium and thorium series, whilst R.Arnoult 37 and K. C. Wang3* have made measurements with thorium-active deposit. All these measurements are important for the inter-pretation of the complexity (fine structure) of normal a-particlegroups and of the emission of long-range a-particles in certain cases.39Accurate numerical comparison 24 completely confirms the inter-pretations originally offered. Fine structure in the normal groupsis present when the product nucleus is left excited after the emissionof the a-particle; the presence of long-range groups, on the otherhand, is evidence of states of excitation consequent upon the trans-formation preceding the a-particle change.In the two cases studied(radium-C’ and thorium-C’), this transformation is of the 8-particletype. The complexity of the normal groups is always of the natureof “ fine structure ” because the y-rays associated with cc-particledisintegrations are never of very high energy; yet the a-particles ofthe long-range groups would be even more infrequent than they areif there were not high-energy y-rays associated with p-particletransformations. There is a t present no explanation for thisqualitative difference between radioactive changes of the two types,for the simplest assumption in either case is that the excitation of thenucleus is an excitation of or-particle levels.Evidence for previousor subsequent excitation of the nucleus shows up most clearly ina-particle disintegrations on account of the discrete energy groupsof the emitted particles; there can he no doubt, however, that it ispresent, at least as regards subsequent excitation, in F-particledisintegrations, also.40 Here, however, the complexity of the upperlimits of the partial continuous spectra cannot be described as finestructure, for the reason already advanced.Interpretation of the natural 8-ray spectra, in so far as thedetermination of y-ray energies is concerned, is relatively simple.In order to deduce intensities (quanta per disintegration), a theoryof internal conversion is necessary. Internal conversion coefficientsfor the more intense components may be deduced experimentallyfrom measurements on “ excited ” and natural @-ray spectra’,respectively ; for the rest, some satisfactory basis of interpolation isrequired. The early experiments showed 41 that no entirelytrustworthy basis was provided by the experimental data alone.37 J .Phys. Radium, 1934, [vii], 5, 67; A., 470; Compt. rend., 1934, 198,38 2. Physik, 1934, 87, 633; A., 342.s9 Ann. Reports, 1932, 29, 310 et seq.40 C. D. Ellis and N. F. Mott, Proc. Roy. Soc., 1933, [ A ] , 141, 502; A.,4 1 C. D. Ellis and G. H. Aston, ibid., 1930, [A], 129, 180; A., 1930, 1339.1603; A,, 713.1933, 1100384 RADIOACTIVITY AND SUB- ATOMIC PHENOMENA.The relevant theory has been developed by H.R. Hulme,42 H. M.Taylor and N. F. Mottt3 J. B. F i ~ k , ~ * and J. B. risk and H. M.Taylor.45 Their value for the internal conversion coefficientdepends very markedly upon the type of nuclear transition in whichthe y-ray quantum is produced. For (electric) quadripole transi-tions, in which the nuclear azimuthal quantum number changes by0 or 2, it is about three times greater than for dipole transitions,in which the change of spin is one unit.46 Thus, spin changes maybe assigned to the various transitions, some as the direct result ofexperimental determinations of internal conversion coefficients,others by a process of comparison of theoretical alternatives.Whenthis has been done, two results emerge : internal conversion coeffi-cients having been assigned to each component of the y-radiation,absolute intensities may be deduced, and, secondly, relative spinvalues may be assigned to all the energy levels in the level systemby which the transitions are de~cribed.~' The data concerninglong-range =-particles and natural p-ray groups are thus susceptibleof comparison otherwise than as regards agreement of energydifferences alone ; from each set of data, excitation probabilitiesmay be deduced for the different levels of the system. To do thisrequires, in the former case, a knowledge of the absolute values ofthe azimuthal quantum numbers concerned, and, in the latter,merely a knowledge of relative values.This detailed comparisonof the two sets of data for radium0 has been made by Rutherford,Lewis, and B ~ w d e n . ~ ~ Other information concerning the spins ofradioactive nuclei will be discussed in connexion with the theory ofP-disintegration (see below).Progress in the separation and purification of large quantities ofprotoactinium 48 has not reached the stage when an accurate valuefor the atomic weight may be obtained by chemical methods,49but the determination of nuclear spin by hyperfine-structureanalysis 86 confirms the general expectation that the mass number isodd.Nuclear Transformations produced by Fast Particles.I. The Production of Stable Species.-In this section and in thenext the effects produced by using a-particles, neutrons, protons, and42 Proc.Roy. SOC., 1932, [A], 138, 643; A., 1933, 110.43 Ibid., p. 665; A., 1933, 111; 1933, [ A ] , 142, 215; A., 1933, 1224.44 Ibid., 1934, [A], 143, 674; A., 342. 45 Ibid., 146, 178; A., 1151.46 This result is complicated somewhat if the radiation fields describing47 C. D. Ellis and N. F. Mott, PTOC. Roy. SOC., 1933, 1.43, 139, 369; A , ,48 G. Gram and H. Kiiding, Naturwiss., 1934, 22, 386; A., 854.4° See Ann. Reports, 1933, 80, 347.the transitions involve magnetic multipole components, also 4 51933, 204FEATHER. 385deuterons 50 as projectiles will be considered in turn, only the workof the past year being described. Table I11 of the report for 1933 51summarises the principal transformations then known to occur ;reference may be made to it for the earlier results.New data have been obtained concerning the trans-formations produced by a-particles bombarding heavy hydrogen, 52lithium, 53 beryllium,54 boron, 55 nitrogen, 56 fluorine, sodium, 58magnesium, 59 aluminium,60 and phosphorus.61 Certain of thesehave been discussed, from a single viewpoint, by H. Pose.62 Themajority of the transformations studied have, as previously, beenthose in which the a-particle is captured, another particle, proton orneutron being emitted in the process. There is some evidence,however, that in certain cases (lithium, nitrogen, fluorine, andaluminium) the nucleus is excited without its capturing the a-particle,and in one case (heavy hydrogen) the results indicate disintegration,also without capture (H2 __P HI + nl).For the rest, the inform-ation obtained may best be presented by tabulation. In Table IVare given particulars concerning potential barriers, as well as themaximum numbers of proton (or neutron) groups observed whena-particles of a single energy are employed. Nuclear symbols are5o This designation is here preferred to " diplon " and " deuton," frequentlyemployed.51 Ann. Reports, 1933, 30, 355.52 (Lord) Rutherford and A. E . Kempton, Proc. Roy. Soc., 1934, [A],143, 724; A., 342; J. R. Dunning, Physical Rev., 1934, [ii], 45, 586; A., 714.53 P. Savel, Corfipt. rend., 1934, 198, 1404; A., 579.J. Chadwick, Proc. Roy. Soc., 1933, [A], 142, 1; A., 1933, 1224; G.Bernaxdini, 2.Physik, 1933, 85, 555; A., 1933, 1225; P. Auger, J . Phys.Radium, 1933, [vii], 4, 718; Compt. rend., 1934, 190, 414; A., 235, 1053;(Mlle.) M. Blau, J . Phys. Radium, 1934, [vii], 5, 61; A., 470; J. R. Dunning,loc. cit.; T. W. Bonner and L. M. Mott-Smith, Physical Rev., 1934, [ii], 46,258; A., 1161; H. R. Crane, C. C. Lauritsen, and A. Soltan, ibid.,.45, 507;A., 714.5 5 J. Chadwick, loc. cit., F. Heidenreich, 2. Physik, 1933, 86, 675; A,,128; R. F. Paton, 2. Physik, 1934, 90, 586; A., 1151; H. Miller, W. E.Duncanson, and A. N. May, Proc. Camb. Phil. SOC., 1934, 30, 549.56 E. C . Pollard, Proc. Roy. SOC., 1933, [A], 141, 375 ; P. Savel, loc. cit. ;H. Stegmann, Physikal. Z., 1934, 85, 636; A., 1053.57 T. W. Bonner and L.M. Mott-Smith, Zoc. cit.5 8 A. Konig, Natuwiss., 1934, 22, 150; 8. Physik, 1934, 90, 197; A.,471, 1151; P. Savel, Eoc. cit.6Q H. Klarmann, 2. Physik, 1934, 87, 411 ; A., 342 ; P. Savel, loc. cit. ;W. E. Duncanson and H. Miller, Proc. Roy. SOC., 1934, [A], 146, 396.60 P. Savel, Compt. r e d . , 1934,198, 368; A., 234; (Mlle.) M. Blau, loc. cit.;0. Haxel, 2. Physik, 1934, 88, 346; 00, 373; A., 580, 1151; G. Ortner andG. Stetter, ibid., 1934, 89, 708; A., 1053; W. E. Duncanson and H. Miller,loc. cit.Physikal. Z., 1934, 35, 633; A., 1053.a-Particles.61 R. F. Pafon, Zoc. cit.REP.-VOL. XXXI. 386 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.listed in col. 1, and in cols. 2 and 3 are given, for each nucleus, theenergies, in millions of electron-volts, which an a-particle mustpossess in order to enter, with reasonable probability, through thetop of the barrier (2) and through the various resonance levels (3),respectively. Col.4 indicates the number of groups (p = proton,n = neutron) in the energy spectrum of the particles emitted. Theimportance of an accurate knowledge of the numbers and positionsTABLE IV.Be@ 3.5 2.5, 1.4 { 2 ( n ) NaZ3 - Kl 2(P) ?(n)Li7 3.0 - l(n) Fl9 5-0 4.0, 3.4 4=2(p) ?(n)B'O 3.6 3.0 5(p) ?(n) Mg(?) 6.5 6.3, 5-7 + 2 ( p ) ?(n)Bfl 3.7 2.4 l(n) AlZ7 6.8 6.61, 5.75, 5.25, 4(p) ?(n) N1' 4.1 3.5 l(p) 4.86, 4-49, 4.0- 3(P) ?(n) P31 -of resonance levels lies in its direct relevance t o any theory of nuclearstructure which may be advanced.Neutrm. Information concerning the production of stableatomic species in neutron-produced transformations has hithertobeen obtained entirely by means of the expansion chamber.Bythis method very little has recently been added to the data previouslyreported upon.63 The use of more intense sources (e.g., thoseobtained by bombarding beryllium with high-velocity deuterons) 64and the knowledge that extremely slow neutrons are frequentlymuch more effective than neutrons of high energy 65 will no doubtresult in a renewal of activity in this field. One of the results whichmay then be anticipated is that additional information will accrueconcerning the positions of resonance levels in the potential barriersof various light nuclei as against a-particles; for most of theneutron-produced disintegrations occur with emission of a-particlesand, when one of these escapes as a disintegration particle withenergy less than that which corresponds to the top of the barrier,it is probable that it leaves the product nucleus through one of theresonance levels.A statistic exhibiting the energies of the dis-integration particles will thus allow the positions of the resonancelevels to be deduced.Evidence for a new mode of disintegration of carbon by neutronshas been obtained by J. Chadwick, N. Feather, and W. T. Davies.66Three tracks having a common origin are, most probably, to beinterpreted in terms o€ the non-capture process C12.-/ 3He4. It6a Ann. Reports, 1933, 30, 352.64 F. N. D. Kurie, Physical Rev., 1934, [ii], 45, 904; Bull.Arner. P h y s k l' 6 E. F e d , E. Amaldi, B. Pontecorvo, F. Rasetti, and E. Segrb, La Bicerm66 Proc. C a d . Phil. SOC., 1934, 30, 357.SOL, 1934, 9, (3), 8.Scient., 1934, 5, (2), 282, 380FEATHER. 387is possible that a similar interpretation holds for the triple forkphotographed in an expansion chamber by L. Misovski,I. Kurtschatov, N. Dobrotin, and I. Gurevit~ch.~~Protm and deuterons. During the past year, a more extendedstudy has been made of the disintegration effects observed withseveral of the lighter elements, and many new modes of transform-ation have been established. The transformations of heavy hydro-geqas lithium,69 berylli~m,~O boron,71 carbon,72 and fluorine 73 havebeen investigated in detail. From boron and carbon " artificial "radioelements are obtained as the result of certain of the trans-formations.These are considered more fully in the appropriatesection of this report. Lithium has been studied in the form of itsseparated isotopes,88 and it has thus been established that thereactions Li6 + H1 + He4 + He3 and Li6 + H2 + Li7 + H1take place in addition to the three reactions previously known.51He3, hitherto unknown, is also produced in one mode of disintegrationof heavy hydrogen by deuterons, H2 + H2 -+- He3 + nl; thealternative mode, in this case, resulting in the production of a thirdspecies of hydrogen, H2 + H2 -+ H3 + H1.cs It is very probablethat these isobaric nuclei, H3 and He3, are both stable.3, 7* With67 Cmpt. rend. A d . Sci. U.R.S.S., 1934, 8, 230; A., 1152.M.L. E. Oliphant, P. Harteck, and (Lord) Rutherford, Nature, 1934,133, 413; Proc. Roy. SOC., 1934, [A], 144, 092; A., 471, 826; P. I. Dee,Nature, 1934,133, 564; A., 580.68 F. Kirchner, Sitzungsber. bayr. Akad. Wiss., 1933, 129; A., 1934, 128;K. Diebner and G. Hoflfmann, Naturwiss., 1934, 22, 119; A., 342; M. L. E.Oliphant, E. S. Shire, and B. M. Crowtlier, ref. (88); F. Kirchner and H.Neuert, Phydka2. Z., 1934,35,292 ; A., 471 ; C . C. Lauritsen and H. R. Crane,Physical Rev., 1934, [ii], 45, 63; H. R. Crane, C. C. Lauritsen, and A. Soltan,Zoc. cit., ref. (54); J. D. Cockcroft and E. T. S. Walton, Proc. Roy. Soc., 1934,[A], 144,704; A., 826; A. Eckardt, R. Gebauer, and H. R. von Traubenberg,2. Phy& 1934,89,582; A., 938; H.R. Crane, L. A. Delsasso, W. A. Fowler,and C. C. Lauritsen, Physical Rev., 1934, [ii], 46, 531.70 H. R. Crane and C. C. Lauritsen, ibkl., 45, 226, 493; H. R. Crane, C. C.huritsen, and A. Soltan, loc. cit.7 1 F. Kirchner and H. Neuert, Physikal. Z., 1933, 34, 897; A., 128; alsoloc. cit., ref. (69); F. Kirchner, loc. cit., and Naturwiss., 1934, 22, 480; A.,938; C. C. Lauritsen and H. R. Crane, Physical Rev., 1934, [ii], 45, 493;L. Kurtschatov, G. Schtschepkin, A. Vibe, and V. BernaschevBki, Compt.rend. Acad. Sci. U.R.S.S., 1934,1,486; A., 579; J. D. Cockcroft and E. T. S.Walton, loc. cit.72 C. C. Lauritsen and H. R. Crane, Physical Rev., 1934, [ii], 45, 345;J. D. Cockcroft and E. T. S. Walton, loc. cit.78 M. C. Henderson, M.S. Livingston, and E. 0. Lawrence, Physical Rev.,1934, [ii], 46, 38; A., 938; E. McMillan, ibid., pp. 326, 868; H. R. Crane,I,. A. Delsasso, W. A. Fowler, and C. C. Lauritsen, loc. cit.74 See W. W. Loder, P. T. Smith, W. Bleakney, G. P. Hrsmwell, and H. D.Smyth, Physical Rev., 1934, [ii], 46, 81388 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.beryllium no single reaction is established with certainty, but it isknown that neutrons are emitted under bombardment withdeuter0ns.~45 75 The disintegrations produced by deuterons onboron are of great complexity ; Blo + H2 -+ 3He4 and B1° +H2 + Bll + H1 are established,76 and neutrons are also emitted.It is now clear that the corresponding proton-produced disinte-gration shows unusual features." The suggestion has been made '*that Bll + HI+ Be8 + He4 is an occasional mode.Underdeuteron bombardment, carbon of mass 12 changes to the nextheavier isotope, protons of a single energy being emitted.76 a-Particles of a single energy are produced when fluorine is bombardedbyEventually, from a detailed study of these and similar trans-formations it will obviously be possible to obtain values for themasses of the initial and product nuclei based entirely upon thedetermined masses of HI, H2, He4, the standard mass 0l6 and theenergy changes observed, so long as the usual conservation laws areassumed. At present the masses obtained in this way are to someextent suspect, and no useful purpose will be served by giving acomplete list. The "observed" energy changes require in manycases an accurate knowledge of the rate of loss of energy of fastprotons and @-particles in mica, and until this is obtained the datamust await a final inter-comparison.It is probable, however, thatthe nuclear mass of He3 is some 0.0006 -+ 0.0004 unit greater thanthat of H3, a result just consistent with the stability of both species.The nuclear binding energies, for structures composed of protonsand neutrons, are approximately 7 and 8 million electron-volts,respectively. The mass of 3'19 seems likely to be about 0.003 unithigher than F. W. Aston's value.sOThe experiments of H. R. Crane, C. C. Lauritsen, and theircolleagues 81 are concerned with the y-rays which are emitted inmany disintegrations. The following is a summary of their results :Fl9 + H1 + 0l6 + He4.y-Ray energy, y-Ray energy,Projectile. Target.e.v. x loe6. Projectile. Target. e.v. xH1 Li 4 and 12 H2 C 3.2H2 Be 0.7 H1 F 5.4Ha B - 2andhigher'5 H. R. Crane, C. C. Lauritsen, and A. Soltan, Ph.ysica2 Rev., 1934, [ii], 45,76 J. D. Cockcroft and E. T. S. Walton, Zoc. cit., ref. (69).?7 F. Kirchner and H. Neuert, Eoc. cit., ref. (69).'9 M. C. Henderson, M. S . Livingston, and E. 0. Lawrence, Zoc. cit.507; A., 714.F. Kirchner, Naturwiss., 1934, 22, 480; A., 938.Proc. Roy. SOC., 1927, [A], 115, 487; A., 1927, 914.LOC. cit., refs. (69)-(73)FEATHER. 389Although it is not possible in every case to fix the transformationin which the y-rays arise, yet it is noteworthy that certain productnuclei may be formed in a number of ways; for instance, Bllresults from the reactions N14 + nl+ Bll + He4 and BlO +H2 + Bll + H1 ; C13 from BIO + He4 .+ C13 + HI, 0l6 +n1 + C13 + He4, and C12 + H2 -+ C13 + H1.There is someevidence that the excited states and the subsequent y-ray emissionfrom such nuclei are independent of the method of their production.Recent information concerning the y-rays accompanying disinte-grations produced by a-particles is due to P. Save1.8211. Tho Production of Unstable Species.-a-Particles. Evidencethat high-energy electrons may be associated with the emissionof heavy particles in artificial disintegration was first obtained by( h e . ) I. Curie and F. Joliot.83 It was shown that both positiveand negative electrons were emitted from thin layers of beryllium,boron, and aluminium bombarded by the a-particles from polonium.From certain differences observed, it appeared that the phenomenonin the case of beryllium was not of the same nature as with the othertwo elements. The positrons from boron and aluminium wereascribed to nuclear processes. Both neutrons and protons wereknown to be emitted from these substances under a-particle bom-bardment, and the hypothesis was advanced that the emission of aproton, and of a neutron together with a positron, were alternativemodes of disintegration.The important discovery was then made 84that the emission of positrons did not cease with the removal of thea-particle source but continued, decreasing in intensity following anexponential law of decay. Similarly, the positron activity duringirradiation rose from zero initially to a limiting value.It was ob-vious that neutron and positron could not be emitted simultaneously ;it was suggested that in all cases a finite time intervened. Theobservations indicated that an unstable species resulted from theinitial disintegration in which neutrons were emitted, and that thisspecies then behaved precisely as a radioelement of short life, thespoataneous emission, however, being of positrons rather than ofelectrons or a-particles. " Artificial " radioelements with character-istic half-value periods were obtained following the disintegrations ofboron, magnesium, and aluminium. Unstable species N13, Si27,pw were postulated, confirmatory chemical evidence being obtainedfor N13 and P30.85 As an example of the schemes proposed, that82 LOC.cit., refs. (53)-(60).83 Ann. Reports, 1933, 30, 354.84 (Mme.) I. Curie and F. Joliot, Compt. rend., 1934, 198, 254; A,, 234.8 s Idem, ibid., p. 559; Nature, 1934, 133, 201; J . Phys. Radium, 1934,[vii], 5, 153; A,, 343, 470, 713390 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.representing the sequence of disintegrations produced by a-particlesbombarding aluminium may be given in full.Si30 +- H1M27+He4'A ~ 3 0 + n1-+ SiW+ a + n1The branching ratio for the primary disintegration is about 20 : 1in favour of the emission of a proton, and the half-value period forpositron (a) emission is 3-22 & 0.1 min.*6 It will be noted that thestable end-product along each branch is the same.The original discovery of positron activity was rapidly confirmed ;the activity resulting from boron and aluminium disintegrationswas observed by (Frl.) L.Meitner,87 that from all three elements byC. D. Ellis and W. J. Henderson.88 New activities following thedisintegrations of nitrogen,89 sodium,gO phosphorus,go and potass-ium91 have since been reported. The activity obtained whenmagnesium is bombarded by a-particles has been shown t o becomplex,g2 positron activity being attributed to SP7, as above,and negative electron activity to A128. The latter activity is themore intense. A128 is formed from Mg25, and Si2' from Mg24, protonsand neutrons being emitted in the respective primary disintegrations.The energy spectrum of the positrons from Pa has been investig-ated by (Frl.) L.Meitner,93 C. D. Ellis and W. J. Hendeksoqs6 andTABLE V.Radio -element.P30sc42 (44)Electron-active A1287 (Inin-).14 f 11.1 f 0.10.12 r;t 0.0213.2 -+ 0.140 f 51802.1 f 0.2A. J. Alichanov, A. J. Alichanian, and B. S. D i e l e p ~ v . ~ ~ Thelast authors have also investigated the corresponding spectra for86 C. D. Ellis and W. J. Henderson, Proc. Roy. Soc., 1934, [A], 146, 206;A., 1161.87 Naturwiss., 1934, 22, 172; A,, 471.88 Nature, 1934, 133, 530; A., 579.89 L. Wertenstein, ibid., p. 564; A,, 579.90 0. R. Frisch, ibid., p. 721; A., 714.9 1 M. Zyw, ibid., 134, 64; A., 939.92 (Mme.) I. Curie and F. Joliot, J .Phys. Radium, 1934, [vii], 5, 163; A.,713; A. J. Alichanov, A. J. Alichanian, and B. S . Dielepov, Nature, 1934,133, 871 ; A,, 826.93 Naturwiss., 1934, 22, 3 8 8 ; A., 825.84 Nature, 1934, 134, 254; A,, 1054FEATHER. 391N13 and A12s (elc~trons).95,~~ At present all these results are notentirely concordant. A provisional list of unstable species and half-value periods (7) is given in Table V.The occurrence of unstable species resulting fromneutron-produced disintegrations was first noted by E. Fermi,96using a strong source of radon-beryllium with fluorine (Cap,) andaluminium as target elements. Previously, the disintegration offluorine by neutrons had been investigated by W. D. Harkins,D. M. Gans, and H. W. New~on,~' the production of an unknownspecies of nitrogen, W6, being regarded as probable.The suggestionwas made that this nucleus might possibly be transformed into 016by emission of a p-particle. Fermi concluded that this, in fact, wasthe case. He found that the half-value period for the p-particletransformation was about 10 secs. Together with his collabor-ators, Fermi has rapidly extended these results.98 More than 60elements have been bombarded, and definite evidence for subsequentactivity has been obtained with more than 40 of them. That theemission of negative electrons is responsible for the greater part ofthis activity has been directly proved in 12 cases. Since the restof the data may be explained almost without exception on thisassumption, it has been tentatively adopted throughout the work.From the nature of the case, the data, obtained refer moreparticularly to the characteristics of the activity produced than tothe primary disintegrations which give rise to the radioactivespecies. So far, it has not been possible to make cloud-chamberstudies of the primary disintegrations ; only chemical methods areavailable.These methods have shown that the activity afterneutron bombardment may be possessed by an element two placesor one place removed in the periodic table from the elementbombarded-or, sometimes, by an unstable isotope of that elementitself. Thus, if the neutron is captured in all transformations,doubly-charged or singly-charged particles or y-radiation must beemitted. The results to date are satisfactorily explained in terms ofa-particles, protons, or quanta as the primary disintegration pro-ducts, the only difficulty being of a theoretical n a t u r e t h a t ofexplaining the apparently high probability of simple capture of theneutron by a heavy nucleus.The remaining types of primaryNeutrons.96 Nature, 1934,133,950 ; A., 939. 96 La Ricerca Scient., 1934, 5, (l), 283.s7 Physical Rev., 1933, [ii], 44, 945.98 See E. Fermi, E. Amaldi, 0. D'Agostino, F. Rasetti, and E. Segre,Proc. Roy. Soc., 1934, [A], 146, 483; E. Ferrni, Nuouo Cim., 1934, 11, 429;E. Amaldi, E. Fermi, F. Rasetti, and E. Segrd, ibid., p. 442; E. Amaldi andE. Segrh, ibid., p. 452, where references t o a series of preliminary reports( A . , 714, 826) are given392 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.disintegration become rapidly less probable as the atomic numberof the bombarded nucleus increases, as theory predicts, but trans-formation by pure capture would appear t o retain a high probabilityfor all elements.It has been suggested, alternatively, that thetransformations observed with heavy elements are non-capturedisintegrations resulting in neutron emission, but this hypothesisis not really satisfactory, and it fails definitely in view of the recentdiscovery 65 that the disintegrations in question become enormouslymore probable as the kinetic energy of the neutrons is reduced almostto “ thermal ” values. In the wealth of the data obtained, manycases are indicated of nuclei which are transformed in two or moreways under neutron bombardment and, conversely, several instancesin which the same unstable species is the result of more than oneprimary disintegration. For example, A12’ disintegrates in threeways and A12* is formed in three disintegration processes.Thus thedecay of activity when certain (pure) targets are activated may beextremely complex. The observations with activated uranium andthorium targets suggest that part of this complexity, in certain cases,must be ascribed to the production of unstable species from whichseries of successive products arise. From a study of the chemicalproperties of the products from uranium, E. Fermi 99 concluded thatunstable species may occur with 2 > 92, but a critical examinationof the evidence by A.V. Grosse and M. S. Agruss does not supportthis conclusion.The extensive investigations carried out in Rome have been followedup in many other laboratories, but no additional discovery of anyfundamental importance has been reported. (Mme.) I. Curie, F.Joliot, and P. Preiswerk2 and R. Fleischmann3 early discoveredthat with some elements y-rays as well as p-particles are emittedduring the decay of activity. That this is frequently the case hassince been shown by E. Fermi and his collaborators. Confirmation ofa large number of results has been obtained by T. Bjerge andC. H. WestcottY4 and a preliminary investigation made of the resultsof varying the mean energy of the neutrons employed, M. S.Livingston, M. C. Henderson, and E.0. LawrenceY5 using “arti-ficially ” produced neutrons exclusively, have studied a number ofelements, whilst other investigations have been carried out byB. Kurtschatov, I. Kurtschatov, G. Schtschepkin, A. Vibe, andNature, 1934, 133, 898; A., 826.1 Ibid., 134, 773; A., 1935, 7.2 C m p t . rend., 1934,198, 2089; A., 826.3 Natuwiss., 1934, 22, 434; A., 938.1 Nature, 1934, 134, 177, 286; A., 939, 1054.5 Proc. Nat. Acad. Sci., 1934, 20, 470; A., 1151FEATHER.. 393L. Misovski6 and J. R. Dunning and G. B. Pegram.' L. Szilardand T. A. Chalmers * have introduced an ingenious method of con-centrating the activity when the unstable species is isotopic with itsparent substance.Finally, it may be remarked that, whilst certain neutron-produceddisintegrations are set in evidence through the radioactivity of theproducts of transformation, it is t o be expected that many otherdisintegrations must occur without being recognised in this way.The investigation of the primary disintegrations of complex heavyelements will obviously be complicated by this fact.Protons and deuterons. The observations of J.D. Cockcroft,C. W. Gilbert, and E. T. S. Walton9 and C. C. Lauritsen, H. R.Crane, and W. W. Harper lo provided the first evidence for the pro-duction of unstable species by bombardment with protons anddeuterons, respectively. The former authors established theemission of positrons from carbon bombarded by protons ; thelatter a similar emission from a number of light, elements subjectedto deuteron bombardment.The effect has since been reported uponby M. C. Henderson, M. S. Livingston, and E. 0. Lawrence,ll C. C.Lauritsen and H. R. Crane,12 and S. H. Neddermeyer and C. D.Ander~0n.l~ At present, carbonis the only element the activation ofwhich by proton bombardment is proved beyond doubt. No recoilphenomena have been observed in the primary transformation andthis andother evidence point to the formation of N13 by simple captureof the proton. Bombardment by deuterons, as above described(p. 388), with many elements results in the emission of protons andthe transformation of one stable isotope into the (stable) isotope ofnext higher mass number. This emission of a proton may sometimesbe replaced by the successive ejection of neutron and positron;when this occurs the intermediate species is unstable, as whena-particles are responsible for the disintegration (see above).Withdeuterons, as with a-particles, the branching ratio is large, in favourof proton emission. If all the results which have been reported aresubstantially correct, then the yield of active product must frequentlydepend very considerably upon the energy of the deuteronsemployed. There is, however, general agreement that N13, ofhalf-value period 11 &- 1 mins., and Cl1, of period about 20 mins.,result from the activation of carbon and boron, respectively. The6 Compt. rend. A d . Sci. U.R.S.S., 1.934, 3, 221, 226; A., 1152.7 Physical Rev., 1934, [ii], 45, 768.8 Nature, 1934, 134, 462; A., 1152.Ibid., 133, 328; A., 342.10 Science, 1934, 79, 234; A., 579.12 Ibid., pp.430, 497.l1 Physical Rev., 1934, [ii], 45, 428.la Ibid., pp. 498, 653.N 394 RADIOACTIVITY AND SUB- ATOMIC PHENOMENA.problem of the identity, or otherwise, of the N13 thus formed andthe active product from boron bombarded by a-particles (p. 389)awaits solution.The Theory of 8-Particle Disintegration.The successful application of the principles of wave-mechanicsto the explanation of the main features of the a-particle disinte-gration was one of the early and most striking achievements of thisnew method of theoretical approach.14 Very few special assump-tions were needed, and progress in this and in the analogous explan-ation of artificial disintegration was relatively rapid.At the presentstage of development, further investigation is unlikely to addmaterially to the accepted theory,l5 and the centre of interest hasshifted to the formulation of a satisfactory theoretical treatment ofthe 8-disintegration. Here no progress is possible without particularassumptions.The form which these assumptions were to take was determinedby several considerations. The discovery of the neutron of massnumber 1 l6 made it possible-if this were significant-to regard allnuclei as built up of particles known to exist in the free state, withoutrequiring for this purpose the presence of electrons in the nuclearstructure. Existing theory was then, and still is, incapable ofdescribing the behaviour of particles of so small a mass within sorestricted a region of space.Next, the relation discovered by B. W.Sargenta2 and the apparently successful ad hoc hypotheses putforward by C. D. Ellis and N. I?. Mott 40 redirected attention towardsthe maximum 8-particle energy as the important parameter in termsof which to work. Furthermore, there was another such hypothesis,due to W. Pauli,17 of earlier date. This postulated the emission ofa second particle (neutrino), having no charge and very small mass,in 8-disintegration; the sum of the kinetic energies of electron andneutrino being constant for all p-transformations between the sameinitial and final nuclei. Finally, the discovery of electron and posi-tron emission from unstable species of widely different atomicnumber (artificial radioactivity) provided new data and a quali-tatively distinct phenomenon (positron activity) which any success-ful theory was obliged to explain.These considerations lead naturally to the theory of E.Fermi.18l4 Ann. Reports, 1930, 27, 317.l5 See H. Casimir, Physica, 1934, 1, 193; A., 234; T. Sex& 2. Physik,16 Ann. Reports, 1932, 29, 305.17 See J. F. Carlson and J. R. Oppenheimer, Physical Rev., 1931, [ii], 38,18 2. Physik, 1934,88, 161; 89, 522; A., 679, 827.1933, 87, 106; A., 127.1787FEA’I’HER. 395His was not, however, the first attempt a t a detailed treatment ofthe problem; it is given priority here merely for convenience ofpresentation. The theory developed by G. Beck l9 derives less fromthe point of view above expressed; it will be considered further inwhat follows.These two theories and other work up to date havebeen discussed by G. Gamow.20 Fermi bases his theory on thenuclear model proposed and developed by W. Heisenberg.21 Forthis model, the sole constituent particles are protons and neutrons,and these two, Fermi regards as different inner quantum states ofa single “particle.” A quantum jump between the two statesresults in the creation of an electron or a positron according as theinitial state of the “ particle ” was neutron or proton state. Aneutrino or antineutrino is simultaneously created, and the pairof particles, electron and neutrino, or positron and antineutrino,are ejected from the nucleus, sharing between them the availableenergy.The probability of such a jump, and so the decay constantfor p-disintegration, depends very notably on the difference inangular momentum between initial and final nuclei. The pro-bability is greatest when there is no change in this quantity. Fromthis point of view, those radioelements to which the upper ofSargent’s two curves is appropriate suffer p-disintegration generallywithout change of nuclear spin (permitted transitions) ; in otherp-transformations this change is not usually zero (forbidden tram-itions). G. Gamow 37 has attempted to develop this conclusion andassign spin values to the normal and certain excited states of thenuclei of successive elements in the thorium series.The neutrino hypothesis was introduced in order to make possiblean explanation of a continuous distribution of energy amongst thep-particles from a given product without violation of the conserv-ation laws.The more detailed evaluation of the particular type ofcontinuous distribution which is found obviously requires moreprecise assumptions concerning the mass of the neutrino. If theseassumptions run counter to established data, the hypothesisnecessarily fails. Fermi has shown that the form of the distributionnear the high-energy limit is sensitive to the assigned mass, whilsta similar sensitivity of the position of the maximum has been deducedby F. Perrin.22 Both authors conclude that the rest mass of theparticle is most probably zero. No immediate contradiction is19 2. Physik, 1933,83, 498; 84, 811; A., 1933, 884, 996; Q.Beck and K.Sitte, ibid., 1933, 88, 106; A., 1933, 1224; 1934,89, 269; A., 826; Nature,1934,138, 722; A., 713.20 Physikal. Z., 1934, 35, 533; A., 827.81 2. Phyaik, 1932, 77, 1; 78, 156; A., 1932, 894, 1074; ibid., 1933, 80,687; A., 1933, 336.aa Cmpt. 9‘t3?Zd., 1933,197, 1626; 198, 2086; d., 1278 827396 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.involved in such a conclusion, On Fermi’s theory, the form of thecontinuous spectrum depends also on the change of nuclear angularmomentum in the disintegration. General differences in form asbetween the continuous spectra corresponding to permitted andforbidden transitions had previously been noticed by C. D. Ellisand N. 3’. M ~ t t . ~ ~ These differences are qualitatively of the typewhich theory predicts. The application of the theory to the caseof positron emission has been worked out by G.C. Dis-crepancies indicate its present imperfections. Criticisms have alsobeen advanced by I. Tamm 24 and discussed by D. I ~ a n e n k o . ~ ~The theory of G. Beck is based on different assumptions. Forhim, inability to treat theoretically the binding of electrons in nucleiis simply evidence for the present inadequacy of the theory; itdoes not follow from this inability-which cannot be proved to bepermanent-that electrons do not exist as nuclear particles. Heassumes, in fact, a structure composed of a-particles, not more thanthree protons and “ free charges.” The latter are electrons which,within the nucleus, retain only their charge and symmetry pro-perties. In @-disintegration there is instability in this system ofcharges, with the result that the net positive charge on the nucleushas to be increased (or, in positron disintegration, decreased) byone unit.Materialisation of energy occurs, as in other known cases,by the creation of a pair of electrons, positive and negative. Onlyone of these electrons escapes from the nucleus.26 The capture ofthe other takes place, in a manner which present theory is unable todescribe, so that only the charge of the particle is retained by thenucleus. Its energy is lost to observation. The feature of p-disintegration which on Fermi’s theory is described in terms of theemission of an unobserved particle, the neutrino, is here representedby this process of capture of the second particle with the loss of itspurely mechanical attributes. No attempt is made to save theconservation laws of macroscopic physics.This procedure may becharacterised by the greater intellectual integrity: it does not onthat account alone make for the more successful theory. Sinceboth the above theories treat the disintegration as a double process,and on each, the disintegration probability depends markedly onthe change in angular momentum, it will not be easy to decideexperimentally between their conclusions until all arbitrary constantsare replaced by quantities which are theoretically derived.Experimental proof of the emission of neutrinos would, of course,23 Atti R. Acd.Gncei, 1934, [vi], 19, 319; A,, 713.2r Nature, 1934, 188, 981; A., 827. 25 Ibid., p. 981 ; A., 827.A suggestion of this type has also been made by M. N. Saha and D. S .Kothari, ibid., 1933, 182, 747; 1934, 188, 99; A., 236FEAmER. 397settle the question, but it is very unlikely that these particles willbe easily ~bserved.~' J. Chadwick and D. E. Lea 28 have shown that,if they are in fact emitted in the disintegration of radium-E, thenthe ionisation which they produce corresponds to less than oneion-pair in 150 km. of standard air. Prom the theoretical view-point, the idea of a neutrino with objective existence appears tohave had some attraction. L. de B r ~ g l i e , ~ ~ J. L. Destou~hes,~~A. P r ~ c a , ~ ~ and B. Kwa132 have attempted to develop a theory ofthe propagation of photons in which neutrino and antineutrino havec2 natural significance.Anomalous Absorption of Hard y-Rays : the Positive Electron.The discovery of the positive electron occurred during the periodcovered by the last report.33 As there described, this new particlewas found, first of all, as one component of the penetrating radiationa t sea-level.It was then established that it might be produced bythe action of high-energy y-radiation on matter, in which mode ofproduction a pair of electrons, one positive and one negative, wasinvariably associated with the disappearance of a quantum ofradiation. Now, such a mode of interaction between radiation andmatter had not until then been considered by experimentalists.There was in existence, however, a theory due to P.A. M. Dirac 34which provided a natural way of regarding the simultaneous appear-ance of pairs of electrons of, apparently, opposite sign of charge,and this a t once provided a basis for theoretical calculations con-cerning the probability of the production of such pairs at the expenseof the quantum energy of electromagnetic radiation. There wasalso in existence considerable experimental evidence 35 to show thatin the absorption of high-energy y-rays, more particularly by sub-stances of high atomic weight, processes were involved which a t thetime had no theoretical explanation. The electronic absorption27 H. Bethe and R. Peierls, Nature, 1934, 133, 532, 689; A,, 580, 714.28 proc. (Jamb. Phil.SOC., 1934, 30, 59.29 C m p t . rend., 1934, 198, 135; A., 236.30 Ibid., p. 467 ; A., 342.31 Ibid., p. 643; A., 343; J . Phys. Radium, 1934, [vii], 5, 157; A., 715.32 Compt. rend., 1934, 199, 23; A., 939.33 Ann. Reports, 1933, 30, 355.34 See Ann. Reports, 1930, 27, 325.35 G. T. P. Tarrant, Proc. Roy. SOC., 1930, [A], 128, 345; A., 1930, 1085;1932, [A], 135, 223; A., 1932, 318; C . Y. Chao, Proc. Nat. A d . Sci., 1930,16, 431 ; A., 1930, 1086; Physical Rev., 1930, [GI, 36, 1619; A., 1931, 142;proc. Roy. Soc., 1932, [ A ] , 135, 206; A., 1932, 318; (Frl.) L. Meitner andH. H. Hupfeld, 2. Physik, 1931, 67, 147; A., 1931, 281; J. C. Jacobsen,&id., 1931, 70, 145; Am, 1931, 995398 RADIOACTIVITY AND SUB-ATOMIO PHENOMICNA.coefficient 36 for y-rays of 2.6 x lo6 e.v.energy was in excess of thesum of the coefficients for photoelectric absorption and Comptonscattering by an amount which appeared to vary directly as theatomic number of the scattering element, and to reach roughly 20%of the total when that element was lead. Recently, sources of arti-ficially-produced ?-rays of still higher energy have become available(see above), and with one of these E. McMillan 73 has shown that,for radiation of 5 4 y\ lo6 e.v. energy, approximately 60% of theabsorption in lead is “ excess ” absorption, whilst a t this energy,also, pe varies linearly with atomic number. H. R. Crane, L. A.Delsasso, W. A. Fowler, and C. C. Lauritsen 69 have extended themeasurements to 12 x lo6 e . ~ . ~ ’ Here the additional absorption inlead is nearly 10 times as great as that due to scattering by extra-nuclear electrons.I n this energy range (1-12 x lo6 e.v.), therefore,the absorption coefficient in lead is not a continuously decreasingfunction of increasing quantum energy, as had previously beensupposed. 7-Rays of about 3 x lo6 e.v. energy are more penetrat-ing (in lead) than radiations of either greater or less quantum energy.Failure to appreciate this fact has doubtless been responsible forinconsistencies in the past : certainly, it renders completely worth-less any estimation of wave-length from absorption measurementsby simple extrapolation of the Klein-Nishina formula beyond therange of radioactive y-ray energies.Now, calculations concerning the excess absorption by pair-production early led to the result that the effective cross sectionper nucleus must vary as the square of the nuclear charge?s i e ., thatthere must be an “ additional” part of tJ.e proportional to theatomic number. It became natural, therefore, to ascribe to theproduction of pairs the observed additional absorption which wasfound t o vary in precisely this way from element to element.Moreover, for the y-ray of 2.6 x lo6 e.v. energy, there was good agree-ment between experimental and theoretical values for this excessabsorption. The calculations have now been extended byY. Nishina, S. Tomonaga, and S. Sakata39 and H. Bethe and W.*e The electronic absorption coefficient (pJ represents the fractional decrewein intensity, per extranuclear electron per cm.a area of a thin absorbing foil,which occurs when the radiation passes normally through the foil.It is also,numerically, the mean cross-sectional area per electron effective in the processof absorption. The atomic absorption coefficient (pa) is defined in a preciselysimilar manner. It may be regarded, when this point of view is significant,as the target area per atomic nucleus effective in absorption.87 The y-ray energy was determined independently by magnetic analysis ofthe secondary electrons produced in the course of its absorption.98 Ann. Reports, 1933, 30, 368.a@ Sci. Paper8 Inst. Phys. Chem, Res. Tokyo, 1934, 24, 1; A, 825FEATRER. 399HeitlerY4O and it is clear that this satisfactory numerical agreementextends over the whole range of investigated energies, say up to12 x lo6 e.v.Prom these results it might thus be concludedthat the production of positron-electron pairs was undoubtedly themechanism by which the hitherto anomalous absorption was to becompletely explained. The extensive cloud-chamber experiments ofJ. Chadwick, P. M. S. Blackett, and G. P. S. Occhialini41 entirelysupport this conclusion.Most of the experiments on anomalous absorption, however,have been concerned with an analysis of the radiation, other thanCompton scattered y-radiation, which is re-radiated by a, targetirradiated by y-rays-either the approximately homogeneous Y’radiation from thorium-C” (2.6 x lo6 e.v. energy), or the veryinhomogeneous radiation from the short-lived products of radon.Here, conclusions are very much less definite.Experiments haverecently been performed by (Frl.) L. Meitner and H. Kosters.8,42E. Stahel and E. Ketelaar,43 T. Heiti11g,4~ L. H. Gray and G. T. P.Tarrant,45 and W. Bothe and W. amongst others. There ianow almost complete agreement that from all scatterers a radiationis emitted, roughly isotropically, of about 5 x lo5 e.v. energy-whether the primary radiation be that of thorium or of radiumactive deposit. Its intensity, per atom of the scatterer, is found tovary as the square of the atomic number; for light elements itrepresents the bulk of the anomalous^' scattering. There isevery reason to believe that this component of the scattered radi-ation arises in the annihilation of positive electrons which have lostalmost all their original kinetic energy.Qualitatively, this is entirelyin agreement with the hypothesis which has been made concerningthe nature of the anomalous absorption. At some stage, the positiveelectrons produced in the pairs must suffer annihilation. Theoryindicates that, for positrons of the energies concerned, a smallproportion only of these annihilation collisions will occur before theenergy has been reduced almost to zero. In most cases, then, theannihilation radiation will be expected to consist of quanta of0.51 x 106 e.v. energy, two equal quanta being emitted for everypositron which disappears.It is rather when the absolute intensity of the radiation is40 Proc.Roy. SOC., 1934, [A], 146, 83; A., 1150.4 1 Ibid., 144, 235 ; A., 468.43 2. Physik, 1933, 84, 137; A., 1933, 883.43 J . Phys. Radium, 1933, [vii], 4, 460; A., 1933, 1224; 1934, [vii], 5, 612.44 Naturwiss., 1933, 21, 800; A., 5; 2. Physik, 1933, 87, 127; A,, 127.45 Proc. Roy. ~ o c . , 1932, [A], 136, 662; A*, 1932, 791 ; 1934, [A], 143, 681,46 Natumuise,, 1934, 22, 106; A s , 342; 2. Physik, 1934,88, 683; A., 713,706 ; A., 342400 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.considered that difficulties first arise. There is, however, no realagreement concerning absolute intensities. L. H. Gray andG. T. P. Tarrant45 find more scattered radiation of about this(annihilation) wave-length than absorption measurements (regardedfrom the point of view of the theory of pair production) wouldpredict ; they suggest, tentatively, the production of double pairsas an explanation, since this would diminish the fraction of theprimary energy dissipated as kinetic energy of electrons andpositrons.On the other hand, there is at present no direct evidencefor the production of more than single pairs by quanta of radio-active energies, although the production of showers in penetratingradiation is generally regarded as essentially the same type ofprocess, many pairs being produced simultaneously when thequantum energy is high.However, a more fundamental difficulty than that caused bydiscrepancies in observed and calculated intensities concerns thehard components of the scattered radiation. The single aspectof agreement, here, is that this component varies in intensity,per atom of the scatterer, considerably more rapidly than thesquare of the atomic number.Even with lead, less than one quan-tum of the more energetic radiation is emitted for every 10 quantaof the less energetic. (Frl.) L. Meitner and H. Kosters42 andW. Bothe and W. Horn46 consider that the hard component isradiation of the same frequency as the primary radiation, but L. H.Gray and G. T. P. Tarrant,45 T. Heiting,u and E. Stahel and E.Ketelaar43 report differently. None of these authors finds anyevidence of appreciable scattering without change of wave-length.Gray and Tarrant estimate a mean energy for the hard componentfrom lead of 1.1 x lo6 e.v., whilst both they and Stahel and Ketelaarconsider that the results contain nothing contrary to the simplestassumption, vix., that the effective wave-length of the hard com-ponent is approximately independent of the scattering material.It is probable that the greatest proportion of this radiation willeventually be found to be annihilation radiation emitted in theannihilation of positrons of considerable klnetic energy.Thismay occur with the production of a single quantum of radiation,or of two quanta. The probability that one or other of theseprocesses will take place does not vary very markedly with theatomic number of the scattering material, but the partial prob-ability of the former of them is very much greater in heavy scatterersthan in light. In scattering substances of low atomic number,the second process will result in unequal quanta, one of energy greaterthan, and the other of energy less than, 0.51 x lo6 e.v.It may beshown that most of the low-energy quanta will have about 0.25 >: 10FEATHER. 401e.v. energy?' It is noteworthy that Gray and Tarrant considerthat the mean quantum energy of the soft component of thescattered radiation is in all cases slightly less than 0.5 x lo6 e.v.At present, there are questions of intensity ratios which must besolved before the above explanation can be accepted, and for thisreason, and in an attempt to explain the reported observation ofscattered radiation of nearly the primary hardness, other suggestionshave been made. For instance, C. C . Lauritsen and J. R.Oppenheimer 48 believe that the production of '' white " X-radiationin the scattering material by recoil- and photo-electrons is capableof explaining some of the results.The hard component of thisradiation would be emitted chiefly in or near the forward direction,and in that direction would have a maximum energy approachingthat of the primary radiation. W. Bothe and W. Horn46 havereported a high-energy hard component of which the emission ishighly anisotropic. C. C. Lauritsen and J. R. Oppenheimer48conclude that coherent scattering by electrons in negative-energystates near the nucleus cannot be sufficiently intense to be in questionhere. The affirmative suggestion was made by M. Delbriick49who, at the same time, had considered the complementary sug-gestion that incoherent (Compton) scattering by such electronsmight occur, but had concluded that it would not.However, thecomplete theoretical calculations for these processes have yet to bemade. From the experimental side, further advance is likely tocome from a study of the scattering from very thin sheets ofmaterial. Stahel and Ketelaar43 and Bothe and Horn46 havemade a beginning in this direction, but the smallest thickness ofscatterer used by the former authors was 0.4 g./cm.2 (lead) and by thelatter authors 0.7 g./cm.2 (carbon). Such scatterers already absorbcompletely a large fraction of the electrons produced in their bulk.The calculations of H. Bethe and W. Heitler 40 apply to pairproduction by fast electrons as well as to the process which hasjust been considered.For equal energies of electron and quantum,it appears that the nuclear cross-section for pair-production isabout 137 times greater for a quantum of radiation than it is for anelectron. C. D. Anderson, R. A. Millikan, S. H. Neddermeyer,and W. Pickering 50 have obtained a few cloud-chamber photo-graphs showing the production of pairs during the passage of high-energy electrons from the penetrating radiation through a leadplate. The frequency of production appears to be roughly as4 7 H. J. Bhabha and H. R. Hdme, Proc. Roy. SOC., 1934, [ A ] , 146, 723; H.Rethe, unpublished.48 Physical Rev., 1934, [ii], 46, 531.60 Physical Rev., 1934, [ii], 45, 352; A., 580.49 2. Phyeik, 1933, 84, 144402 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.calculated.D. Skobeltzyn 51 has published a single photographwhich is best interpreted as showing the production of a pair by anelectron of a few million electron-volts energy whilst traversing thegas in the cloud chamber. Other rare events of a similar naturewhich might occasionally be observed have been discussed by3'. Perrin 52 from a theoretical standpoint.Since it has now been esthblished that positron-electron pairsmay be produced by the interaction of quanta and of fast electronswith the fields of force surrounding atomic nuclei, and s i b e bothquanta and fast electrons are emitted from the nuclei of certainradioactive substances, it is interesting t o consider the possibilityof " internal-conversion " effects, whereby the emission of pairsmay replace the emission of quanta in some instances, or accompanythe emission of electrons (of reduced energy) in others.There hasbeen definite evidence for some time 53 that sources of radon,radio-thorium, or thorium-active deposit enclosed in thin-walledglass tubes emit positive as well as negative electrons, and a certainamount of evidence that this effect, of the order of 1% of the total@-particle emission, is to be attributed to the radioactive substanceitself. The calculations of L. Nedelsky and J. R. Oppenheimermake it rather unlikely that the chief cause here is internal conversionof y-radiation. More recent experiments of A. J. Alichanov andM. S. Kosodaev,55 who used a radon source and magnetic analysis,have provided further data on the subject.From this it seemsprobable that the appearance of positrons is connected with thenuclear emission of electrons in radioactive @-decay.The recently-discovered emission of positive electrons fromnuclei in " artificial radioactivity " is discussed more fully in anotherplace (p. 389). It remains to remark here that, whilst fairlysuccessful formal theories of this effect have been advanced, theirconnexion with the original theory of pair-production is not alwaysvery apparent. That theory has to describe the materialisation ofparticles (with conservation of charge) a t the expense of kineticenergy or of the energy of electromagnetic radiation; the theory of@disintegration is concerned with materialisation taking place atthe expense of the potential energy of a complex system.If thesimple idea of pair-production is retained, it is necessary to postulatea mechanism by which only a single member of the pair is observedNature, 1934, 133, 23 ; A., 127.52 Cmpt. rend., 1933, 197, 1100, 1302; A., 1934, 6.63 J. Thibaud, Compt. rend., 1933, 197, 915; A., 1934, 4; J. Chadwick,P. M. S. Blackett, and G. P. S. Occhialini, Zoc. cit. (ref. 41) ; D. Skobeltzyn andE. Stepanowct, Nature, 1934, 133, 565, 646; A., 578.54 Physical Rev., 1933, [ii], 44, 948; 1934, [ii], 45, 136, 283.55 2. Physik, 1934, 98, 249; A., 1160FEATHER. 403outside the nucleus ; if it is not retained, then some new assumptionmust be made. The properties of the positive electron, once it hasleft the nucleus, are in no way different from those of a positronproduced in any other way; its observability must be regarded asdependent upon the continued existence of a vacancy in an electronstate of negative energy, whilst its ultimate annihilation is describedas the capture of an originally observable (negative) electron intothis vacant state.In any self-consistent theory, the initial appear-ance of this vacancy must eventually be described in terms of thetransitions of negative electrons.Experiments designed to demonstrate the properties of positiveelectrons have been carried out by E. J. Williams,56 using thepositrons produced in the " additional " absorption of y-rap,by J. Thiba~d,~' employing the positrons from a radioactivesource, and by F.J o l i ~ t , ~ ~ with the positrons emitted by certainartificially produced radioelements. Certain outstanding difficultiesin the theory of the positron have been discussed from variousviewpoints by V. F o c ~ , ~ ~ W. H. Furry and J. R. OppenheimerJG0Y. Nishina and S. Tomonaga,61 W. Heisenberg,62 and P. A. M.D i r a ~ . ~ ~Various possibilities of interaction between y-radiation and atomicnuclei have already been discussed, but amongst them no case ofinteraction specific to any nucleus has so far been considered.The processes involved merely require the existence of very strongelectric fields in order to possess appreciable probability; such fieldintensities are to be found only in the neighbourhood of an atomicnucleus.Very recently, however, two cases of specific interactionhave been recorded. J. Chadwick and M. Goldhaber 64 subjectedheavy hydrogen gas to the action of the y-rays from a radiothoriumsource. They obtained evidence of the liberation of protons withconsiderable energy. It became obvious that a nuclear photo-effectwas in question, the reaction being written H2 + W,, = H1 + n1 +&, W,, and Q being respectively the y-ray energy and the sum of the58 Nature, 1934, 133, 415; A., 470.57 Compt. rend., 1933, 197, 915, 1629; 1934, 198, 562; Ann. Soc. sci.Bruxelles, 1934, [B], 54, 36; Physical Rev., 1934, [ii], 45, 781; A., 4, 126,341, 468, 825.58 C m p t . rend., 1933,197, 1622; 198, 81; J . Phys. Radium, 1934, [vii], 5 ,299 ; A., 126, 236, 1064.59 C m p t .rend. Acad. Sci. U.R.S.S., 1933, 267; A., 341.60 Physical Rev., 1934, [ii], 45, 246; A., 468; ibid., pp. 343, 903.61 Japan. J . Physics, 1934, 9, 35; A., 578.62 8. Physik, 1934, 90, 209; A., 1160.63 Proo. Camb. Phil. SOC., 1934, 30, 160.64 Nature, 1934, 134, 237; A., 1063404 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.kinetic energies of the liberated particles. This reaction fixes themass of the neutron as 1-0080 & 0.0005 on the atomic scale(0l6 = 16). Later, L. Szilard and T. A. Chalmers 65 detected theneutrons produced in the analogous photo-disintegration ofberyllium ; the y-rays from radium-active deposit were employed.The Penetrating Radiation.The general picture of the character of the penetrating radiationpresented in this report last year 66 remains almost unchanged.Electrified particles (the majority probably positive electrons)approach the earth from outer space and, in their passage throughthe atmosphere, produce secondary and tertiary radiations, partlyelectronic, partly very probably quantum in character, with manyof the electronic tertiaries arising in " showers " of zero net charge.If, however, there has been little change in this picture, it mustnot be concluded either that the volume of work on this particularsubject is less than formerly or that complete agreement has beenreached amongst the many workers in the field.There is at present,for instance, almost complete disagreement concerning a possibleneutron component of the radiation.Thus G. L. Locher 67 andL. V. Misovski and M. S. Eigenson 68 have reported affirmativelyregarded its presence from cloud-chamber observations, althoughnegative results have been obtained by (Mme.) I. Curie andF. Joliot t39 and E. Regener and R. Auer,TO using ionisation-chambermethods. Neither is there any real agreement regarding theincidence of high-energy protons, or other heavy charged particles,as possible components of the radiation. W. Kolhorster 7l andA. C0rlin,7~ having extended the range of depth observations tothe equivalent of about 600 m. of water, still find evidence of someionisation due to external agents. It has been suggested, e.g., byA. H. Compton and H. Bethe,73 that high-energy protons alone couldpossess such extreme penetrating power, coupled with the otherobserved properties of this radiation.Another suggestion, byA. H. Compton and R. J. Stephenson,74 directed towards explaininga feature of the high-altitude absorption curves, involves protonsor multiply-charged particles of lower energy. This may become65 Nature, 1934, 134, 494; A., 1151.e7 J . Franklin Inst., 1933, 216, 673; A., 1934, 235.6a Cmpt. Tend. Acad. Sci. U.R.S.S., 1934, 2, 221 ; A,, 714.69 J . Phys. Radium, 1933, [vii], 4, 492; A., 1933, 1225.70 Physikal. Z., 1934, 35, 784; A., 1152.71 Nature, 1934, 133, 419; A., 471; 2. Phyeik, 1934, 88, 536; A., 580.72 Nature, 1934, 133, 63 ; A., 128.73 Ibid., 134, 734.70 Physical Rev., 1934, [ii], 45, 441; A., 580.Ann.Reports, 1933, 30, 358FEATHER. 405untenable in view of the recent results of E. Regener and G . Pf~tzer,'~who found that the increase in intensity with height up to about28 km. above sea-level was very closely the same whether the in-tensity was determined by tube counters or, as has been more usualhitherto, by ionisation chambers. Obviously, a closer comparisonof the data from these two methods is desirable. Finally, there isconsiderable difference of opinion concerning the amount and qualityof any quantum radiation which may enter at the top of theatmosphere along with the particle radiation which has already beenassumed. Moreover, opinions upon this question will obviouslyinfluence the status assigned to the electronic showers-whetherthese be considered as tertiary or secondary phenomena.Afterthese preliminary comparisons, the year's experiments may now bereviewed somewhat more systematically.The most direct information is obtained from cloud-chamberphotographs taken in strong magnetic fields. Here, C. D. Anderson,R. A. Millikan, S. H. Neddermeyer and W. Pickering 50 have ex-tended the earlier results of Anderson. At sea-level, individualelectrons and, more particularly, positrons, may have energiescertainly up to 5 x loQ e.v.; electrons and positrons occurring inshowers have smaller energies. The maximum total energy of theparticles in a single shower has not so far exceeded the limitobserved for single particles. Many instances of showers producedin material screens contained in the cloud chamber have been found,the majority of them having obviously been produced by some non-ionising radiation.Large numbers of low-energy electrons andpairs produced both in the screens and in the gas filling the chamberare almost conclusive proof of the occurrence of quanta of aboutlo7 e.v. energy simultaneously with the showers. It is presumedthat the non-ionising radiation of higher energy is also quantum incharacter. By evaluating, from observed track curvatures, the lossof energy of electrons traversing screens of carbon and lead, largerandom losses are established-chiefly in lead. The evidencesupports the view that a quantum radiation is emitted.Less direct evidence concerning the shower-producing radiationis obtained from observations with several tube counters. First,however, it should be mentioned that the use of two widely separ-ated counters with interposed absorption screens of variable thick-ness allows of an analysis of the corpuscular radiation at any placein respect of its penetrating power-an analysis only one stage lessdirect than that in respect of magnetic deflectability, provided bythe counter -controlled expansion chamber operated in a magnetic75 Physihl.Z., 1934, 35, 779; A., 1162406 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.field. Following W. Bothe and W. K~lhorster,~~ B. Rossi'' hasbeen the chief exponent of this method. Together WithBottecchia,78 he has completely established the validity of themethod, held to be suspect, at one time, by R.A. -Nlillikan*7gRossi also was the first to employ three counters in a study ofshowers and the shower-producing radiation. Recently, thisarrangement has been very widely used. E. Funfer,sl J. El-SawyerYe2 C. W. Gilbert,83 and G. Alocco and A. Drigo 84 haveobtained results here in which there is a large measure of agreement.These experiments show, first, that, for any locality, the showerparticles produced in a given substance are for the most partfairly homogeneous with respect to energy (C. W. Gilbert83finds that this characteristic energy increases from about 7 X 10'e x to lo8 e.v. from sea-level to about 3.5 km. altitude), and,secondly, that the absorption of the main shower-producingradiation, particularly in heavy elements, is very much more rapidthaa that of the primary penetrating radiation.The atomicabsorption coefficient for the latter varies roughly as the atomicnumber of the absorbing material;85 for the former this coeffi~ient,~~as well as the target area of the nucleus effective in shower pro-d u c t i ~ n , ~ ~ appears to vary as the square of the atomic number.Shower production, therefore, seems to be the principal mode inwhich the so-called shower-producing radiation interacts with matter.The linear absorption coefficient in lead for the shower-producingradiation a t sea-level is about 0.35 cm.-l. It may be noted thatthis is not many times smaller than the calculated limiting value:'for high quantum energies, of the coefficient for pair-production bynuclear interaction of electromagnetic radiation. Moreover, thedependence of absorption coefficient upon atomic number is seen tobe the same for pair-production by relatively low-energy quantaas it is for shower production by the radiation which is responsiblefor the showers. Thus, all the evidence suggests that this radiationis, in fact, high-energy quantum radiation ; similarly it indicatesthat present theory is inadequate fully to describe the absorption'13 Ann. Reports, 1930, 27, 322.77 2. Physik, 1933, 82, 151 ; Physical Rev., 1934, [ii], 45, 212.78 La Ricerca Scient., 1934, 5, (l), 171.70 Phy8kl Rev., 1933, [ii], 43, 661.*O Physikal. Z . , 1932, 38, 304.*l 2. Physik, 1933, 83, 92.82 Phygical Rev., 1933, [ii], 44, 241; A,, 1933, 996.83 Proc. Roy. SOC., 1934, [A], 144, 559; A., 827.84 La Ricerca Schnt., 1934, 5, (l), 112.Since the ratio of atomic number to mass number does not differ muchfrom one atom to another, this dependence of pa on Z expresses the fact thatthe mss absorption coefficient is approximately the same for all substancesFEATHER. 407processes, although obviously possessing a measure of truth. Ifthe shower-producing radiation be secondary to the primarycorpuscular radiation, then the different dependence of their absorp-tion coefficients upon atomic number requires that the equilibriumratio of secondary to primary radiation should be greatest forsubstances of low atomic weight. The three-counter absorptioncurves are consistently explained on this assumption. Fromexperiments with ionisation chambers, H. Schindler 86 had alreadyconcluded that transition effects occur when the radiation passesfrom one medium to another, and that these may be explained interms of the readjustment of equilibrium ratios between primaryand secondary radiations. It is probable that the two sets ofexperiments provide evidence for one and the same phenomenon.There remains one feature of the ionisation due t o the penetratingradiation which it is possible to investigate only in ionisationchambers of large gas capacity. This is the phenomenon of ion-isation bursts or “ Stosse.” 87 These bursts have been investigatedby E. G. Steinke and H. Schindler 88 and by W. Messers~hmidt,~~amongst others. Amounts of energy are involved of the same orderof magnitude as that released in the showers, but its dissipation asionisation occurs in a much smaller volume than is possible for themost complex shower so far observed. It is very unlikely, therefore,that ‘( showers ’’ and ‘( bursts ” are of the same essential character.The frequency and size of the bursts in it given chamber dependmarkedly upon the nature and thickness of the material immediatelysurrounding the chamber. Information concerning the identity ofthe burst-producing radiation will no doubt be obtained by a closerstudy of this dependence. It seems already improbable that theprimary corpuscular radiation is the immediate agent.The question of the time dependence of the intensity of thepenetrating radiation has received further elucidation by W.Messerschmidt.go The greater part, at least, of a small apparentfluctuation in the intensity of the unfiltered radiation with a periodof it solar day is traced to the changes brought about by fluctuatingtemperature in the distribution of radioactive gases in the atmo-sphere. Any true fluctuation has an amplitude of less than O-ZC)’,,.Finally, it is not possible to record any real progress towards adecision concerning the origin of the penetrating radiation. Theonly novel suggestion during the year has been that of L. G. H.86 2. Physik, 1931, 72, 625; A,, 1932, 5.87 Ann. Reports, 1932, 29, 314.8 8 2. Physik, 1932, 75, 115; A., 1932, 556.8Q Ibid., 78, 668; Physikal. Z., 1933, 34, 896; A., 1934, 128.Bo 2. PhySik, 1934, 87, 800; A., 343408 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.HuxleyYgl that the earth, maintained at a high negative potentialby electrons emitted from the sun, is able to endow with the observedhigh energies, through electrostatic attraction, such positivelycharged particles as happen to be in its neighbourhood. It isdoubtful, however, how far such a suggestion will stand the test offurther investigation, experimental and theoretical.N. FEATHER.91 Nature, 1934, 134, 418; A., 1152

ISSN:0365-6217    

DOI:10.1039/AR9343100368

出版商:RSC    

年代:1934

数据来源: RSC

摘要:

INDEX OF AUTHORS’ NAMESABDERHALDEN, E., 334.Abel, E., 17.Abel, J. J., 238.Abello, T. P., 90.Acharya, C. N., 353.Achmatowicz, O., 279.Acree, F., 260.Acree, S. F., 305.Adam, F. H., 242.Adam, N. K., 156.Adams, N. I., 381.Adams, R., 151, 152, 282.Adams, T. W., 343.Adickes, F., 194, 202.Adkins, H., 197, 198.Adler, A. A., 324.Adler, E., 269, 300.Agarbiceanu, H. I., 93.Agruss, M. S., 392.Ahrens, H., 36, 88.Akabori, S., 267, 303.Alben, A. O., 357.Alber, H., 320.Alcock, R. S., 342.Alden, J. P., 304.Alder, K., 265.Alichanian, A. J., 390.Alichanov, A. J., 390, 402.Allam, F., 347.Allen, A. O., 50, 253.Allen, C. F. H., 150, 284.Allen, C. G. F., 303.Allen, J. S., 143.Allen, W. M., 209.Alles, R., 239.Allison, F., 372.Allison, F.E., 346.Allison, R. V., 356.Almasy, F., 290.Almoslechner, E., 365.Almquist, H. J., 56.Alocco, G., 406.Alten, F., 290, 297, 299, 300.Altschuler, S., 85.Alyea, H. N., 18.Amaldi, E., 386, 391.Ambler, H. R., 294, 295.Anderson, C. D., 393, 401, 406.Anderson, D. A., 348.Anderson, F. G., 356.Anderson, J. S., 102, 103, 117.Anderson, L. C., 13, 260.Anderson, 0. E., 84, 377.Andrews, D. H., 27, 30.Angell, F. G., 117.Anger, V., 315.Appleyard, M. E. S., 48.Arayama, N., 334.Arbusov, A. E., 203.Archibald, F. M., 301.Ardagh, E. G. R., 286.Armstrong, E. F., 165.Armstrong, G., 133.Armstrong, K. F., 165.Amaud, A., 237.Arndt, F., 193, 194.Arnot, F. L., 80.Arnoult, R., 383.Amy, A. C., 353.Arragon, G., 163.Arthur, P., 24.Ashley, (Miss) M.F., 15, 84, 377.Ashley, S. E. Q., 296.Askew, H. O., 354.Astbury, W. T., 80.Aston, F. W., 94, 95, 96, 97, 98, 368,Aston, G. H., 383.Atanasiu, J. A., 297.Aten, A. H. W., 115.Aubel, E., 334.Audrieth, L. F., 66.Auer, R., 404.Auger, P., 385.Auhagen, E., 334.Auhagen, T., 334.Ault, R. G., 179, 182.Austin, W. C., 163, 169, 176.Auwers, K. von, 144, 196.Aynsley, E. E., 57.369, 371, 372, 379, 388.Babcock, H. D., 98.Bach, F., 19, 55.Bacher, R. F., 377.Bachmann, W. E., 244, 248.Backer, H. J., 150, 282.Bader, G., 101.Bader, J., 240.Bedoche, M., 247.BBckstrom, H. L. J., 48, 56.BEir, R., 36.40410 INDEX OF AUTHORS' NAMES.Baggesgaard-Rasmussen, H., 75.Bahl, R. K., 116.Bailey, C.R., 35.Bailey, R. W., 88, 102.Bainbridge, E. K., 98.Baird, D. K., 182.Bairstow, S., 50.Baker, J. W., 77.Baker, W., 41.Balarew, D., 285.Baldwin, 1. L., 348.Ball, G. L., 154.Ball, T. R., 296.Ballard, S. S., 377.Balz, G., 105.Bandte, G., 219, 232.Banga, I., 187.Banina, L. P., 300.Banneret, R. A., 154.Bannister, L. C., 136.Bardhan, J. C., 325.Barger, G., 267, 268, 269, 275, 277.Barker, E. F., 15.Barnes, T. C., 345.Barsha, J., 189.BartholomB, E., 15, 16, 17, 29, 31,Barton-Wright, E., 353.Bastow, S. H., 128.Bates, F., 163.Bates, J. R., 13, 55, 56.Bateson, S., 382.Batim, A., 288.Bauer, F., 63.Bauer, O., 139.Bauer, W. H., 55.Baughan, E. C., 80.Bauguess, L. C., 342.Baw, H., 283.Bawn, C. E. H., 18,20, 196.Baxter, G.P., 96, 370.Bayerle, H., 275.Bayler, P. L., 23.Beamer, C. M., 301.Beattie, F., 340.Beatty, H. A., 293.Beak, G., 372, 395.Becke, F., 274.Becker, G., 124.Becker, J., 165.Becker, R., 91.Beckham, L. J., 197.Beckmann, S., 148.Bedf'ord, M. H., 70.Bein, K., 87.Beiser, W., 203.Belcher, D., 74.Belchetz, L., 252.Boll, R. M., 23.Bell, R. P., 18, 20, SO.Belvoussov, M. A., 356.Benedicks, C., 128.Benevolenskaja, Z. V., 273,36, 82.Bengough, G. D., 135.Bennett, A. H., 309.Bennett, G. M., 143, 283.Bentley, J. B., 103.Benz, F., 216.Berchet, G., 162.Berg, C. P., 341, 342.Berger, F., 283.Berger, K., 105.Bergmann, C. W., 134.Bergmann, E., 283.Bergmann, M., 171.Bergstresser, K. S., 296.Bergstrom, F.W., 54.Bernal, J. D., 42, 86, 229, 328.Bernardini, G., 385.Bernaschevski, V., 387.Berner, E., 192.Berry, A. J., 312.Berthoud, A., 48, 55.Bethe, H., 397, 398, 401, 404.Beutler, H., 83, 92.Bewilogua, L., 36.Bhabha, H. J., 401.Bhagavantsm, S., 23, 35.Bickford, C. F., 60.Bigelow, N. M., 219, 237, 242, 251.Biltz, W., 115, 123, 124, 125, 126.Birch, J. W., 309.Birge, R. T., 98.Birkenbach, L., 23.Birr, E. J., 66.Biswas, H. G., 330.Bjerge, T., 392.Bjerrum, N., 26, 68, 78.Blackett, P. M. S., 399, 402.Blair, C. M., 143.Blair, H. T., 139.Blanchard, A. A., 99.Blanchard, M. H., 78.Blanck, E., 354.Blau, (Mlle.) M., 385.Bleakney, W., 16, 21, 98, 369, 371,Bleier, P., 261.Bliss, H. H., 314.Bloom, A., 303.Blount, B.K., 279.Blue, R. W., 15.Bobko, E. V., 357.Bocciarelli, D., 379.Bode, H., 145.Bodendorf, K., 203.Bodycote, E. W., 176.Boekenoogen, H. A., 146.Bottger, O., 256.Boggess, D., 267.Bohne, A., 220.Bolla, G., 24.Bolliger, A,, 298.Bommen, B. W., 128.Bone, W. A., 50.Bonhoeffer, K. F., 19, 55, 251, 262.387INDEX OF AUTHORS' NAMES. 41 1Bonino, G. B., 31.Bonner, J., 359, 363.Bonner, T. W., 385.Bonstedt, K., 212.Booker, J. E., 65.Bordner, E. R., 27.Borgmenn, C. W., 136.Boschan, F., 273.Bose, M. K., 298.Bossanyi, I., 69.Bossert, K., 330.Bosshard, W., 170.Bost, R. W., 303.Bothe, W., 399, 400, 401, 406.Bottecchia, G., 406.Bourgh, A., 90.Bourguel, M., 23, 28, 30.Bowden, B. V., 381, 384.Bowden, E., 21.Bowen, E.J., 47, 48, 51.Boyd-Barrett, H. S., 250.Boys, S. F., 87, 148.Boysen-Jensen, P., 360, 361, 362.Brackett, F. P., 56.Bradfield, A. E., 52.Bradley, C. A., 15.Bradley, W., 198.Bragg, (Sir) W. H., 80, 111.Brammann, G. M., 76.Branch, G. E. K., 56, 241.Brandt-Rehberg, P., 318.Branham, J. R., 293, 294.Brantner, H., 299, 320.Bratu, E., 17.Braun, W., 280.Brctuns, D. H., 149, 167.Brauns, F., 189.Braunstein, A. E., 337.Bredereck, H., 176.Breit, G., 373, 374, 376.Brewer, A. K., 371.Brickwedde, F. G., 17.Briggs, G. H., 382.Briggs, L. H., 279.Bright, W. L., 78.Brigl, P., 164, 166, 167, 168.Brill, R., 104.Briscoe, H. T., 78.Briscoe, H. V. A., 14, 124, 125, 320.Britton, S. C., 128, 136.Brockway, L. O., 38.Brode, W.R., 289.Brodrnenn, L., 61.Brbnsted, J. N., 67, 68, 71, 72, 73,75, 76, 78, 79, 138.Brookbank, E. B., 295.Brown, A. S., 60, 75.Brown, C. T., 300.Brown, F. S., 42.Brown, G. E., 255.Brown, P. E., 348.Brtingger, H., 207, 308, 323.Brugger, W., 261.Brukl, A., 121, 122.Brun, J., 13.Bruni, G., 14.Brunnert, W., 202.Bryan, J. M., 140.Bryant, S. A., 116.Bryddwna, W., 152, 282.Buchanan, G. N., 119.Buehler, C. A., 304.Bunning, E., 369, 364, 366.Bukina, V. V., 300.Burawoy, A., 243.Buret, R., 246.Burg, A. B., 109.Burgess, H., 195, 196.Burkhart, L., 351.Burriel, F., 312.Burstall, F. H., 116, 117, 153.Burton, H., 242.Bury, C. R., 42.Bushnell, C. B., 249.Bussemaker, B. B., 218.Buston, H. W., 365.Butenandt, A., 207, 209, 211, 212,213, 214, 215, 258, 259, 326, 327.Butler, J.A. V., 59, 133.Byme, G. T., 264.Byrns, A. C., 56.Bywaters, W. G., 255.Cabannes, J., 24, 32, 35.Cady, L. C., 310, 311, 212.Caldwell, J., 353.Caldwell, R. M., 353.Caley, E. R., 300.Calfee, J. D., 304.Calfee, R. K., 357.Calingaert, G., 293.Calloway, T. C., 43, 195.Cambi, L., 106.Cameron, H. K., 130.Cameron, J. M. L., 303.Campbell, I. S., 84, 377.Cannan, R. K., 307, 308.Carlson, G. H., 197.Carbon, J. F., 394.Carney, E. S., 119.Carothers, W. H., 146, 158, 160 101,Carpenter, (Sir) H. C. H., 122.Carr, E. P., 253.Carrington, H. C., 182.Carroll, W. It., 348.Casimir, H., 394.Caspari, W. A., 112.Cassal, A., 99.Cassie, A. B. D., 35.Cates, J., 134.Cattle, M., 355.Cawood, W., 95, 97, 295.Centnerszwer, M., 138.Chadun, A., 354.162412 INDEX OF AUTHORS’ NAMES.Chadwick, H., 115.Chadwick, J., 386, 386, 397, 399,Chaix, M., 256.Chakravorty, P.N., 211.Challinor, S. W., 189, 190.Chalmers, T. A., 393, 404.Chalmers, W., 159.Chambers, R., 307.Chambers, T. S., 50.Chandlee, G. C., 76, 300.Chang, C., 282.Chang, T. C., 300.Chao, C. Y., 397.Chapman, A. T., 55.Chapman, A. W., 129.Chapman, R. P., 77, 313.Chapron, J., 31.Chen, A. L., 239, 240.Chen, K. K., 239, 240, 280.Chen, T. T., 308, 309.Cheng, H. C., 30.Chenicek, J. A., 152.Childs, W. H. J., 98.Cholodny, N., 358, 359, 362.Chow, B. F., 155, 251.Christian, W., 331.Christiani, A. von, 259.Chuang, C. K., 210, 232.Chytil, J., 297.Clark, A.J., 335, 338, 339.Clark, H. E., 349.Clark, J., 150.Clark, W. M., 306, 307, 308, 309, 312.Clarke, S. G., 140.Claussen, W. H., 17.Clemo, G. R., 270.Clift, F. P., 303.Cloetta, M., 219, 220, 232, 234, 236.Clusius, K., 15, 16, 17, 18.Coates, J. E., 64.Cobler, H., 211, 326.Cockcroft, J. D., 381, 387, 388, 393.Coelingh, W. M., 352.Coffi, C. C., 50.Coffman, D. D., 197.Coffman, L., 143.Cohen, A., 214.Cohen, B., 306, 307, 308, 309, 312.Cohen, S. L., 325.Cohen, V. W., 377.Cole, J. R., 357.Colin, H., 354.Collatz, H., 334.Collie, C. H., 381.Collins, A. M., 220, 221, 222, 223.Compton, A. H., 404.Compton, J., 168.Compton, L. E., 353.Conant, J. B., 76, 197, 199, 242, 244,Cone, W. H., 310, 311, 312.Conn, M.W., 303.402, 403.251.Connell, (Miss) L. C., 59.Connor, R., 197.Conrad, J. P., 350.Conrad-Billroth, H., 23, 52.Constable, F. H., 127.Contardi, A., 150.Cook, J. W., 214, 325, 327.Cook, R. G., 70.Cook, R. P., 303.Cooper, L. H., 316.Corlin, A., 404.Cornubert, R., 145.Cortelezzi, V., 115.Courtot, C., 255.Cowap, M. D., 100.Cowperthwaite, I. A., 59.Cox, E. G., 117, 118, 153.Cox, R. F. B., 204.Cox, W. M., 62.Craemer, E. O., 161.Craft, H. A., 340.Craig, K. A., 300.Crane, H. R., 385, 387, 388, 393, 398.Crawford, F. W., 30.Crawford, M. F., 84.Crew, M. C., 122.Criegee, R., 216.Crigler, (Miss) E. A., 23.Crist, R. H., 16, 291.Crone, H. G., 47, 253.Cross, P. C., 93.Crowfoot, (Miss) D., 229, 328.Crowther, B.M., 378, 387.Cullinane, N. M., 255.Cupery, M. E., 162.Curie, (Mme.) I., 389, 390, 392, 404.Curie, (Mme.) P., 382.Curry, J., 88.Curtis, G. H., 155.Curtis, W. E., 85, 373.Dadieu, A., 22, 26, 30, 37.D’Agostino, O., 391.Dale, J. K., 176.Dalin, G. A., 16.Dalmer, O., 187, 333.Daniel, H. A., 301.Daniels, F., 55, 56, 93.Danilov, S., 170.Dannenbaum, H., 207.Dansi, A., 150.Darbyshire, J. A., 134.Darrow, D. C., 80.Daure, P., 36.Davey, R. G., 255.David, K., 325.Davidson, J., 355.Davidson, 0. W., 350.Davidson, S., 107.Davies, E. E., 366.Davies, W. T., 386.Davis, C. O., 20INDEX OF AUTHORS’ NAMES. 41 3Davis, D. W., 244.Davis, H. M., 27.Dawson, D. H., 15.Day, 3. N. E., 89.Dearns, (Miss) P., 283.De Broglie, L., 397.Debye, P., 39, 62, 67.DBcombe, J., 197.Dee, P.I., 387.De Gier, J., 369.De Groeve, P., 150.De Jong, L. E. den D., 366.De Kronig, R. L., 15.138 la Praudikre, E. L. A. E., 47.Delbanco, A., 75, 76, 78.Delbriick, M., 401.Delsasso, L. A., 387, 398.Demmel, M., 299.Demole, V., 187, 332, 333.Dempster, A. J., 371.Denbigh, K. G., 114.Denisoff, A. K., 81.Dennis, L. M., 120, 123.Dennison, D. M., 15, 35.Denny, F. E., 352.Dent, C. E., 146, 264.De Riols, J., 24.Dersch, F., 163.Destouches, J. L., 397.Deubner, A., 62.Deulofeu, V., 168, 324.De Vito, G., 350.Deyrup, A. J., 74, 77.Diamond, H., 67.Dickinson, B. N., 153.Diebner, K., 387.Dieck, G., 380.Dieckmann, W., 191, 204.Dieke, G. H., 15, 47, 82.Diels, O., 264, 265.Dietz, N., 77.Dilthey, W., 243.Dingwall, A., 74, 155.Dintzess, A.I., 50.Dirac, P. A. M., 32, 397, 403.Dirscherl, W., 207, 324.Ditz, E., 162.Doak, B. W., 354.Dobbelstein, O., 250.Dobrotin, N., 387.Dodds, E. C., 325.Doehlemann, E., 17.Dole, M., 14, 60.Dolk, H. E., 360, 361.Donisenko, Y. L., 162.Dooley, A., 56.Dorfmann, D., 340.Dorgelo, H. B., 252.Dornte, R. W., 80, 144.Dorough, G. L., 160.Downes, H. C., 72, 79.Drew, H. D. K., 117, 118, 122, 147,152, 153.Ilrigo, A., 406.Drikos, G., 242.Druce, J. G. F., 125.Drucker, C., 85.Dubsky, J. V., 297, 298, 300, 317.31)u Buy, W. G., 362.Iliirr, W., 173.Iliising, J., 125, 126.Jhffendaek, 0. S., 92.Ihfraisse, C., 246, 247.Iluncan, A.B. F., 47.lluncanson, W. E., 385.Dunning, J. R., 385, 392.Ihxhinsky, R., 149.I l u Vigneaud, V., 340, 341.Ilwyer, F. P., 153.Dyer, H. M., 341.Ilykstra, H. B., 162.Ilielepov, B. S., 390.Eagle, H., 308. .Earp, D. P., 143, 283.Eastman, A. S., 56.Eberle, H., 260.Ebert, L., 292.Eckardt, A., 387.Edgcombe, L. J., 295.Edlbacher, S., 342.Edmonds, S. M., 312, 314.Edwall, J. T., 78.Eggleton, M. G., 338.Eggleton, P., 338.Ehlers, R. W., 74.Ehmann, E. A., 100, 101.Ehrenstein, M., 262.Eichelberger, W. C., 76.Eichenberger, E., 208, 323.Eigenson, M. S., 404.Eisenbrand, J., 277.Eisenbrand, L., 277.Elderfield, R. C., 225, 226, 227, 228,230, 233, 235, 236.Elema, B., 308.Ellett, A., 373, 377.Ellis, C. D., 382, 383, 384, 390, 394,Hlod, E., 189.Elvehjem, C.A., 331.Nmbree, N. D., 74.Emde, H., 272.EmelBus, H. J., 14.Enderlin, E., 247.Engler, J., 171.Erlbach, H., 174.Erlenmeyer, H., 14, 345, 346.Eropkin, D. I., 371.Erxleben, H., 216, 361, 365.Escher, R. V., 242.Estermann, I., 374.Ettel, V., 163.Eucken, A., 36, 88, 91.Euler, H. von, 186, 330, 334, 366.396414 IXDEX OF AUTHORS' NAME&Evens, E. A., 240.Evans, M. G., 64, 92.Evans, R. D., 380.Evans, U. R., 127, 128, 132, 136, 137,Evantova, N. S., 162.Evering, B. L., 253.Ewald, L., 240, 241.Eyring, H., 13, 20.138.Faessler, A., 288.Fajans, E., 19.Fajans, K., 71, 240.Falkenhagen, H., 62, 63.Farkas, A., 16, 18, 19, 20, 55, 376.Farkas, L., 16, 18, 19, 20, 53, 54, 55,Farmer, R.H., 143.Fasold, K., 263.Favorski, A. E., 250.Feather, N., 386.Feigl, F., 101, 299, 302, 315, 017.Feldman, P., 56.Fels, E., 209, 326.Fermi, E., 35, 85, 373, 386, 391, 392,Ferner, G. W., 301.Fernholz, E., 210, 211, 212, 232,Ferramolo, R., 314.Ferrante, J., 303.Ferrari, J., 324.Fesefeldt, H., 380, 381.Fessenden, R. W., 70.Finch, G. I., 135.Finkelnburg, W., 83.Fischer, Hans, 263.Fisoher, Hellmut, 300, 316.Fischer, J., 304.Fischer, R., 320.Fischer, W., 62.Fisher, N., 198.Fisk, C. F., 47.Fisk, J. B., 384.Fleck, E. E., 228.Fleck, H. R., 297.Fleischmann, R., 392.Fletcher, C. J. M., 49.Flexser, L., 74.Fock, V., 403.FiSrster, J., 138.FiSrster, T., 16.Forbech, V., 343.Forbes, G. S., 56.Forbrich, L.R., 149.Forse, R., 150.Fosbinder, R. J., 57.Foster, J. S., 14.Foucry, 304.Foulk, C. W., 296.Fowler, R. H., 20, 42, 81, 86.Fowler, W. A., 387, 398.56, 376.394.326.Fox, J. J., 113.Fox, M., 377.Friinkel, E., 320.Franck, J., 91.Frank, J. M., 55.Franklin, E. C., 111.Franklin, M. C., 202.Fred, E. B., 346, 347, 348.Fredga, A., 149.Freeman, J. R., 142.Freese, C., 219, 233.Frehden, O., 315.Frere, F. J., 297.Freudenberg, K., 154, 164, 173.Freund, N., 335.Freundlich, H., 133, 157, 260, 261.Freymann, (Mme.) M., 24.Friedheim, E., 306, 308.Friedrich, A., 300.Friend, J. A. N., 14, 137.Fries, K., 283.Friese, H., 201, 202.Frisch, 0. R,., 390.Frisch, R., 374.Frisch, S., 377.Fromherz, H., 50, 67.Frommer, L., 56.Frost, A.A., 13, 18.Frost, A. V., 50.Fucks, W., 63.Funfer, E., 406.Fujise, S., 256.Fulweiler, W. H., 292.Funk, H., 299.FUOBS, R. M., 60, 65.Furman, N. H., 310, 311, 312, 313,Furry, W. H., 403.Furter, M., 146, 209.314.Gad, H., 291.Gaddie, R., 335.Gartner, H., 14, 345, 346.Gale, J. G., 303.Gall, H., 107, 108.Gallagher, T. F., 324.Gamow, G., 85, 376, 378, 395.Gans, D. M., 380, 391.Garelli, F., 298.Garratt, A. P., 56, 82.Gaviola, E., 92.Gebauer, R., 387.Geddes, A. L., 50.Geest, H., 63.Geffcken, W., 59.Geib, H., 252.Geilmann, W., 124, 125.Georges, L. W., 168.@or@, C. E., 347.@or@, K., 133.Gershinowitz, H., 82.Chose, T. P., 271, 278INDEX OF AUTHORS’ NAMES. 415Gibbs, H. D., 307, 308, 312.Gibbs, R.C., 14.Giblin, J. C., 300.Gidvani, B. S., 204.Giese, H., 121.Gilbert, C. W., 393, 406.Gilfillan, E. S., 14.Gilman, H., 255.Ginsburg, N., 15.Girard, A., 207, 214.Gire, G., 140.Gisolf, J. H., 377.Glasebrook, A. L., 49, 252, 253.Glass, H. M., 62.Glasstone, S., 143, 283.Glattfield, J. W. E., 149.Glikmann, S., 188.Glissmann, A., 82.Glocker, R., 288.Glockler, G., 27, 31.Glomaud, G., 297.Glowatski, E., 63.Godchot, M., 145.Goebel, H., 366.Goebel, M. T., 244.Gorbitz, C., 78.Goldberg, M. W., 146, 207, 208, 261,Goldhaber, M., 376, 403.Goldman, F. H., 70.Goldschmidt, H., 71, 78.Goldschmidt, S., 164, 240, 247.Goldsohmidt, V. M., 39, 119.Goldsworthy, E. C., 56.Gollnow, H., 377.Gomberg, M., 248.Goodeve, C.F., 56.Goodhue, L. D., 78.Goodyear, G. H., 365.Gorbach, G., 320.Gorski, M., 358.Gorter, C. J., 359.Goslin, R., 372.Gothlin, G., 333.Goubeau, J., 23.Gould, A. J., 16, 98, 371.Grace, N. S., 377.Grainger, J., 353.Granath, L. P., 84, 377.Grctssmann, P., 27, 35.Gratiss, 0. A., 381.Graue, G., 384.Grave, T. B., 230.Gray, L. H., 399, 400.Gray, N. M., 377.Greenane, F. J., 297.Greenspan, J., 70.Greenwood, A. W., 325.Grieneisen, H., 253.Grieve, R., 328.Griffiths, H. N., 154.Griffiths, J. G. A., 186.G r i m , H. G., 106.262, 323.Gross, H., 188.Gross, P., 19, 74.Gross, S. T., 36.Grosscup, C. G., 121.Grosse, A. V., 380, 392.Cirossmann, E., 90.Grove, C., 74.Grunberg, A. A., 118, 152, 153.Grussner, A., 177, 182, 184, 332.Gucker, F.T., 59, 60.Gunther, E., 165.Guggenheim, E. A., 73, 75.Guggenheimer, K., 83, 85.Guha, B. C., 330.Guigrich, N. S., 86.Gdlien, R., 83.Gulland, J. M., 177.Gumlich, W., 247.Gundell, W., 364.Gunzert, T., 126.Gupta, J., 298.Gurevitsch, H., 270.Gurevitsch, I., 387.Gustw, E. L., 219, 220, 221, 222,223, 224, 226, 226, 232, 233, 234,236.Gutschmidt, H., 18.Gutzeit, G., 297.Gwynne-Jones, E., 84.Gyorgy, P., 330, 331.Haack, E., 219.Haagen-Smit, A. J., 358, 361, 365.Haaae, L. W., 297.Haber, F., 81.Haddock, L. A., 298.Hneussler, H., 272.Hagen, H., 124, 125.Hagen, S. K., 317.Hahn, G., 267, 269.Helban, H. von, 74.Halford, J. O., 13, 78, 250.Hall, F. G., 76.Hall, J. I., 119.H:tll, N. F., 21, 76.Hdl, W.L., 308, 309.Haller, A., 203.Hdler, H. L., 260.Hamill, W. H., 19.Hamilton, R. H., jun., 304.Hammerschmidt, H., 59.Hrtmmett, L. P., 74, 76, 77, 312, 313,Hammick, D. L., 102.Hampson, G. C., 143.Ran, K., 30, 31.Hanle, W., 36.Ham, R. M., 163.Hansen, I., 35.Hansen-Damasohm, I., 34.Hanson, W. T., 17.Hide, A. H a , 96.314416 INDEX OF AUTHORS' NAMES.Hantzsch, A., 71, 76, 79, 105, 194,Harada, M., 13.Hardy, J. H., 15.Harkins, W. D., 29, 380, 391.Harmon, J., 244.Harmsen, H., 14, 378.Earned, H. S., 71, 74.Harnwell, G. P., 371, 387.Harper, H. J., 301.Harper, S. H., 228.Harper, W. W., 393.Harris, L. J., 309.Harrison, D. C., 333.Harteck, P., 13, 16, 54, 253, 254, 376,Hartelius, V., 364, 365.Hartley, (Sir) H.B., 51.Hartmann, M., 209, 326.Hartree, D. R., 88.Hartt, C. E., 355.Hasenkamp, J., 263.Hassan, A., 43, 195.Hatt, H. H., 151.Ham, R. R., 29.Hausen, S. von, 349, 361.Haussler, E. P., 324.Hawes, W. W., 66.Rawley, E. E., 344.Haworth, R. D., 215.Haworth, W. N., 171, 172, 175, 17177, 179, 182, 183, 184, 186, 18188, 189, 190, 192, 332.Haxel, O., 385.Hayashi, T., 30, 31.Head, F. S. H., 153.Hebbs, L., 142.Hecht, F., 299, 320.Heck, J. E., 300.Hedges, E. S., 128, 132, 138.Heidelberger, M., 219, 220.Heidenreich, F., 385.Heidt, L. J., 56.Hein, F., 66.Bein, W., 302.Heisenberg, W., 32, 395, 403.Heiting, T., 399, 400.Heitler, W., 397, 401.Helfenstein, A., 237.Helferich, B., 164, 165, 172, 176.Hemmeler, A., 299.Henderson, G.H., 382.Henderson, M. C., 380, 387, 388, 392,Henderson, W. J., 390.Hendricks, S. B., 80, 111.Henze, H. R., 143.Herbert, R. W., 177, 182.Herold, P., 196.Herrendarfer, E., 281.Herrmanns, L., 219.Herszfinkiel, H., 379.Hertlein, H. F., 23.243.387.393.Hertz, G., 14, 378.Hertzfeld, K., 254.Herzberg, G., 46, 83, 88.Herzberg, L., 88.Herzfeld, K. F., 49, 90.Herzog, J., 257.Hess, K., 161, 192.Hesse, G., 239, 279.Hessling, G. von, 194.Hettner, G., 82.Heukeshoven, W., 354.Heuse, W., 95.Hevesy, G. von, 346, 37'3.Hewett, C. L., 214, 325.Hey, L., 77.Heydenburg, N. P., 373, 377.Heymann, K., 250.Heyn, A. N. J., 358.Heyroth, F. F., 328.Hibbert, H., 143, 189.Hickinbottom. W. J.. 166.Hieber, W., 100, 101,'102.Higasi, K., 29, 37.Higley, L.A., 198.Hildebrand, J. H., 17.Hildebrandt, F., 207, 325.Hilditch, T. P., 154.Hilgert, H., 66.Hill, D. W., 170.Hill, E. S., 308.Hill, J. W., 146, 158, 160,Hille, E., 299, 300.Hillemam. H.. 228.91.Hiltner, W., 296.Hinshelwood, C. N., 18, 37, 49, 50,Hirsch, P., 305, 308, 309.Hirst, E. L., 171, 172, 175, 176, 177,179, 182, 183, 186, 187, 189, 190,192, 332.Hirtz, H., 100.Hitchen, C. S., 280.Hixon, R. M., 78.Hoagland, G., 155.Hoar, T. P., 128, 136, 137, 138, 139.Hochstatter, W., 272.Hochstetter, H. von, 173.Hock, H., 101.Hockett, R. C., 163, 176.Honigschmid, O., 95, 96, 370.Hoverstad, T., 134.Hofer, A. W., 348.Hofer, E., 346.Hoffmann, A., 219, 220, 230, 237.Hoffmann, G., 387.Hofmann, A., 218, 237, 238.Hogness, T.R., 119.Hohlfelder, L. P., 62.Hohlweg, W., 209, 326.Holiday, D., 365.Holiday, E. R., 177, 330.Holland, E. B., 353.Holland, W. E., 249.52, 53, 54INDEX OF AUTHORS’ NAMES. 417HHHHHElR€lHHHBH aBBRBBBHHHBHHBBHBBBBBI3BHBHBRBBI31HHHHHB:olleck, L., 129.lollens, (Miss) W. R. A., 112.:ollo, E., 348.:olmes, EL H., 56.:olroyd, G. W. F., 115.:olschneider, F. W., 270.:olst, W., 15.:alter, H., 317, 319.lolzen, H., 258.lolzer, H., 299, 301.:omer, C. E., 137.:omelen, M., 304.longen, H., 78.loo, V., 303.:ood, G. R., 62.:oover, C. R., 96.:opkins, E. W., 346, 348.roriuti, J., 20, 21, 57.:om, W., 399, 400, 401.:ornery R.G., 23.lorton, A. T., 47.:osemann, R., 379.:ouston, B., 304.:ouston, W. V., 25.Loward, H. W., 303.iromatka, O., 270.hie, C. T., 303.Lubbard, J., 90.Ludson, C. S., 163, 164, 167,iuckel, E., 241.iuckel, W., 193.iiirbin, M., 146, 261, 262.Iuggins, M. L., 80.iughes, A. H., 57, 156.[ughes, E. D., 20, 89.hghes, E. E., 305.hlett, G. A., 296.d m e , H. R., 384, 401.Xse, R. E., 120.iulthbn, E., 15, 21.[umber, L. M., 286.:umoller, F. L., 163, 176.hnt, H., 300.lunter, E., 49.:unter, H. L., 120.lunter, R. F., 89, 103.hpfeld, H. H., 397.htchinson, A. W., 76.:uxley, L. G. H., 408.Iykes, D. V., 366.176.Iball, J., 144.Imschenetzki, A. A., 366.Ing, R. H., 270.Inglis, D.R., 85.Iagold, C. K., 20, 21, 89, 98, 242.Ingold, (Mrs.) E. H., 98.Inoue, Y., 154.Isbell, H. S., 176.Isbell, R. N., 197.Ishii, R., 301.REP.-VOL. XXXI.Ishiwatari, S., 277.Ittmann, G. P., 35.Ivanenko, D., 396.Ives, D. J. G., 74.Jackson, D. A., 84, 377.J-acob, L., 163.J’acobi, R., 210, 226.Jacobs, W. A., 218, 219, 220, 221,222, 223, 224, 225, 226, 227, 228,230, 232, 233, 234, 235, 236, 237.Jacobsen, J. C., 381, 397.Jacobson, R. A., 162.Jaffe, E., 298.Jitkdb, W. F., 126.Jttkubowicz, B., 208.James, F. W., 14.JfLmes, G. V., 332.James, H. M., 88.James, T. C., 145.Ja,mes, W. O., 355.Jamiick, A., 74.Janot, M., 366.Jeans, (Sir) J. H., 90.Jefferson, M. E., 80.Jenkins, F. A., 97.Jenkins, R. O., 80.Jensen, H., 239, 240, 280.Jeppeson, M.A., 23.Jerofejev, B. V., 61.Jessop, G., 114, 115.Jevons, W., 88.Jezewski, M., 63.Jezowska, B., 126.Job, A., 99,Joffe, J., 84, 377.Johner, W., 382.Johnson, C. H., 116.Johnson, C. R., 95.Johnson, H. W., 353.Johnson, W. C., 119, 120, 121, 122.Johnston, C. W., 344.Johnston, (Miss) H., 15, 377.Johnston, H. L., 15, 16, 20.Joliot, F., 389, 390, 392, 403, 404.Jones, C. B., 341.Jones, C. P., 353.Jones, E. G., 84, 377.Jones, G., 60, 62.Jones, G. G., 114.Jones, J. K. N., 183.Jones, L. T., 55, 56.Jones, P. T., 58.Jones, T. O., 21.Jones, W. J., 163.Jones, W. O., 62.Joos, G., 71.Jordan, L. A,, 158.Joseph, S. M., 120.Josephson, K., 174.Jowett, M., 334.Jitkobson, 299.418 INDEX OF AUTHORS’ NAMES.Juchum, D., 250.Jukes, T.H., 78.Julian, P. L., 267.Jung, F., 186.Jungers, J. C., 54.Just, K., 81.Juza, I. R., 126.Kabat, E. A., 299.Kliding, H., 286, 384.Kaess, F., 107.Kahn, M. J., 89.Kahovec, L., 258, 276, 320.Kalckar, F., 376.Kallmann, H., 85, 98, 372.Kamai, G., 150.Kamecki, J., 63.Kamerling, S. E., 155.Kamner, M. E., 70.Kane, N. L. R., 138.Kantor, T., 319.Kao, C. H., 302, 304.Kapfenberger, W., 370.Kappanna, A. N., 69, 70.Kappes, E., 269.Karagunis, G., 242.Karrer, P., 216, 329, 330, 334.Karstrom, H., 349.Kasinathan, S., 365.Kassel, L. S., 50.Kast, W., 86.Kattschmitt, H., 247.Kaufmann, O., 357.Kellog, A. M., 295.Kellog, H. B., 295.Kellogg, J. M. B., 377.Kelly, T.L., 303.Kelner, I., 255.Kempton, A. E., 386.Kemula, W., 162.Kenworthy, L., 142.Kenyon, J., 175.Kerstan, G., 354.Ketelaer, E., 399, 400, 401.Keuning, K. J., 150, 282.Khan, M. J., 34.Kharasch, M. S., 152.Khromov, S. I., 162.Kidson, E. B., 354.Kiessling, W., 336.Kilpetrick, M., 70, 78, 139.Kilpatrick, M. L., 78.King, A., 14.King, C. V., 75.King, F. E., 256, 266.King, H., 208, 272.K!ng, J. C., 295.King. W. G., 139.Kinnersley, EL W., 328. Kina? K., 164.Kipping, F. B., 149.Kirby, P. H., 142.Kirchner, E., 210.Kirchner, F., 387, 388.Kirk, P. L., 317, 318, 319.Kirkpatrick, W. H., 255.Kiss, A. von, 69, 70.Kisser, J., 316.Kistiakowsky, G. B., 47, 50, 82, 253.Klager, K., 257, 258, 259.Klages, F., 191.Klar, R., 19, 21, 371.Klarmann, H., 385.Kleff, P.A., 303.Klein, W., 172.Klemenc, A., 57.Klemm, W., 122, 123.Knaggs, (Miss) I. E., 11 1.Knapper, J. S., 300.Knauf, A. E., 151.Kneser, H., 90.Kneuer, A., 270.Knick, H., 228, 229.Knippenberg, E., 290, 299.Knoop, H., 190.Knop, J., 310, 311, 313.Knunjanz, I. L., 273.Kobe, K. A., 295.Kobel, G., 171.Kobel, M., 334, 337.Koblitz, W., 57.Koch, F. C., 324.Koch, K., 359, 362.Kogl, F., 216, 358, 361, 365.Koehler, J. F., 92.Koehn, C. J., 331.Konig, A., 385.Koenig, A. E., 119.Konig, W., 335.Koppl, F., 26, 29, 30.Kosters, H., 399, 400.Kofler, L., 320.Kohlrausch, K. W. I?., 22, 23, 26, 28,29, 30, 31, 37, 196.Kohman, E. F., 139.Kolhorster, W., 404, 406.Kolthoff, I. M., 76, 299, 304, 310,Komarovski, A.S., 316.Komatsu, S., 352.Komppa, G., 148.Kon, G. A. R., 204, 228, 220.Kondo, H., 277.Kondrateev, V. N., 371.Konek, F. von, 247.Koningsberger, V. J., 352.Konopicky, K., 129.Konovalova, R., 270.Konsand, W., 279.Kopfermann, H., 84, 377.Korenman, J. M., 315.Kortum, G., 74.Koschara, W., 329.Kosodaev, M. S., 402.liosting, P. K., 142.311, 312INDEX OF AUTHORS’ NAMES. 41 9Kotake, M., 279, 280.Kothari, D. S., 396.Kott, A. E., 121.Kovarik, A. F., 381.Krabbe, W., 203.Kraemer, E. O., 188.Kraft, K., 178, 182, 332.Kraft, L., 216.Kramhr, E.7 333.Kramers, H. K., 32.Kraus, C. A., 65, 66, 119, 122.Krauskopf, K. B., 55.Krauss, A., 371.Krauss, F., 121.Krauze, M. V., 50.Kreis, W., 218, 238.Krishna, S., 271, 278.Krishnamurti, P., 23, 33.Krishnan, K.S., 22.Krishnan, T. S., 305.Krohnke, F., 263.Kroeker, E. H., 204.Kroepelin, H., 260.Krohn, D., 257.Kron, A., 204.Kruger, F., 134.Krumholz, P., 101.Kubelkova, O., 313.Kubota, T., 256.Kiichler, L., 13.Kueck, P. D., 371.Kuffner, F., 271, 275.Kuhn, H., 84, 377.Kuhn, R., 164, 263, 308, 329, 330,Kuhn, W., 87.Kulska, 0. A., 316.Kun-Hou-Lih, 67.Icuntara, W., 283.Ihrano, K., 13.Kurarj, M., 298.Kurie, F. N. D., 386.Kurmies, B., 297.Kursanova, A. I., 273.Kurtschatov, B., 392.Kurtschatov, I., 387, 392,KUPZ, T., 36.Kutz, W. M., 197, 198.Kutzelnigg, A., 128.Kwal, B., 397.Kwasnik, W., 134.331.Labriola, G., 250.La Forge, F. B., 170.Laibach, F., 359, 360, 361.Lambert, P., 23.LaMer, V.K., 19, 59, 68, 69, 70, 73,Lamm, O., 187.Land6, A., 85.Landsberg, G., 22.Langbein, W., 76.76, 79.Lange, B., 290.Lange, E., 17, 59.Lange, J., 58, 60.Lange, W., 59.Langer, R. M., 379.Langer, T. W., 74.Langmuir, I., 99, 102.Langseth, A., 27, 35, 36, 82.Lansing, W. D., 161, 188.Lapin, L., 302.Larrick, L., 373, 377.Larsen, K. D., 27.Larson, E. J., 345.Larsson, E., 78.Lasareff, W., 98.Lashmet, F. H., 344.Laubengayer, A. W., 119.Laurence, V. D., 62.Lauritsen, C. C., 385, 387, 388, 393,398, 401.Lauti6, R., 95.Lawrence, E. O., 387, 388, 392, 393.Lawson, W., 325.Lea, D. E.. 397.Lebedev, S. F., 163.Lecher, H., 247.Lecomte, J., 23, 82.Lederer, E., 267.Lee, A.It., 135.Leegaard, F., 343.Leermakers, J. A., 48, 49, 253, 2Lehmaiin, E., 203, 219.J,ehrer, G. A., 123.Lehrman, L., 299.Lei, H. H., 302, 304.Leighton, P. A., 51, 64.Leitch, (Miss) G. C., 270.Leithe, W., 282.Lenglen, M., 301.Lennard-Jones, J. E., 46.Leo, M., 245.Leopoldi, (Frl.) G., 300.Lespagnol, A., 164.Lemieau. It.. 23.c.Losiheirn’, H.’, 89, 103.Lesslie, (Miss) M. S., 151, 152, 283.Letort, M., 50, 308.Lettmayr, K., 316.Leiipold, E. O., 188.Leutert, P., 100.Ltwene, P. A., 165, 166, 167, 170,171, 174, 176.Lovy, E. A., 16.Lowis, C. M., 25.Lowis, G. N., 15, 17, 83, 98, 345.Lewis, H. B., 341.Lewis, R. D., 357.Lewis, W. B., 381, 384.Lewis, W. R., 48.Lewisohn, M., 121.Liang, T. H., 255.Libby. W. F., 379.Licb, H., 320420 INDlX OF AUTHORS’ NBAdES.Lifschitz, I., 243.Lignana, M., 133.Liguori, M., 266.Linckh, E., 105.Lind, S.C., 254.Linderstrom-Lang, K., 317, 319.Lingane, J. J., 304.Links, R., 320.Linstead, R. P., 146, 264.Littmann, O., 192.Liu, M. Y., 190.Livingston, M. S., 387, 388, 332, 393.Livingston, R., 254.Livschitz, I. A., 163.Locher, G. L., 404.Lochte-Holtgreven, W., 92.Lohnis, M. P., 346.Low, E., 130.Law, O., 129.Lohmann, K., 336, 337, 338, 339.Lohmann, W., 182, 332.Long, J. S., 154.Longsworth, L. G., 61.Lonsdale, (Mrs.) K., 144.Loofbourow, J. R., 328.Loofman, H., 297.Loring, H. S., 340.Lormand, C., 326.Lowe, A. R., 146, 264, 320.Lowry, T. M., 71, 72, 114, 183, 196,Lozier, W. W., 369, 371, 387.Lub, (Mlle.) W.A., 382.Lucy, F. A., 51. *Ludewig, H., 267, 269.Ludwig, H., 281, 284.Lueck, R. H., 139.Lucker, O., 202.Lundegardh, H., 289.Lundsgaard, E., 337.Lupin, F. von, 245.Lutz, R. E., 199.Lux, H., 200.Lyman, C. M., 365.196.Ma, T. S., 302, 303, 304.McAulay, A. L., 128, 138.McBain, A,, 353.McClelland, W. E., 247.McCombie, H., 255.McConkey, H. A. C., 196.Macdonald, R. T., 17, 98.MacDougall, E. J., 346.McElvain, S. M., 198, 202, 203, 204.McHargue, J. S., 356.McHatton, L. P., 114.Machemer, H., 171, 188.Macht, D. I., 238.Machu, W., 129, 130.McIlroy, R. J., 300.McInnes, D. A., 60, 61, 74, 75.MoKay, H. A. C.. 62.MoKellar, A., 15.McLay, A. B., 84.McMillan, E., 398.Macmillan, W. G., 255.Macnaughtan, D.J., 140.Macrae, T. F., 177.Madgin, W. M., 62.Miider, M., 379.Magat, I. M., 24.Mahr, C., 298.Maier, J., 241.Majima, R., 280.Makarov, S. Z., 300.Makashima, A. N., 162.Makino, Y., 352.Malkani, T. J., 352.Malkin, T., 159.Malsch, J., 62.Mamoli, L., 213.Manchot, W., 105, 107, 408, 125, 126.Mandelstam, L., 22.Mann, F. G., 117.Mann, T., 338.Manneback, C., 32.Mannich, C., 269.Manning, W. M., 47.Mano, G., 382.Mantell, C. L., 139.Manzoni-Ansidei, R., 3 1.Marck, L. F., 50.Margraff, I., 262.Marhenkel, E., 201.Markov, M., 87.Marks, S., 155, 156.Marrian, G. F., 325.Marshall, (Miss) M. A., 276.Marten, A., 258, 259.Martin, A. E., 113.Martin, W. H., 22.Martini, H., 109, 110.Martius, C., 186, 193.Maruschkin, M.N., 300.Marvel, C. S., 244.Maschmann, E., 361.Maskell, E. J., 352.Mason, C. F., 70.Mason, R. B., 70.Mason, T. G., 352.Masamoto, B., 246.Mathers, D. S., 175.Matsuno, K., 30, 31.Mattauch, J., 370.Matthews, (Mrs.) J. W., 320.Matveev, V. A., 377.Maurer, K., 163, 179, 332.Maxwell, L. R., 80.May, A. N., 385.May, F., 192.Mayer, J. E., 80.Mazza, L., 379.Mears, R. B., 137.Mecke, R., 28, 82, 98.MBdrtrd, L., 23INDEX OF AUTHORS' NAMES. 421Meisel, K., 123, 124.Meitner, (Frl.) L., 390, 397, 399, 400.Mellon, M. G., 300, 301.Mellor, D. P., 153.Melville, H. W., 18, 54.Mendlik, F., 267, 268.Meng, K. C., 303.Menon, B. K., 145.Menschick, W., 67.Menschikov, G., 270.Menzel, D. H., 98.Merck, 258.Merrill, A.T., 163.Messerschmidt, W., 407.Messner, G., 59.Metzger, H. H., 250.Metzner, P., 364.Meyer, G. M., 165, 167.Meyer, H., 239.Meyer, J., 208, 323.Meyer, K. E., 261.Meyer, R., 265.Meyer, S. L., 345.Meyerhof, O., 334, 336, 337, 339.Michael, A., 195, 196.Michaelis, L., 78, 305, 306, 308.Micheel, F., 167, 169, 170, 178, 182,Mignonac, G., 162.Mik6, J. von, 304.Milas, N. A., 155.Miles, F. D., 188.Milhiet, 301.Miller, H., 385.Miller, O., 23.Milligan, W. O., 112.Millikan, R. A., 401, 405, 406.Millrnan, S., 377.Mills, J. E., 108.Mills, W. H., 41, 150.Milone, M., 23.Milroy, T. H., 340.Minsaas, J., 176.Misovski, L., 387, 393, 404.Mitchell, A. D., 313.Mitchell, H. H., 344.Mitchell, J. E. H., 115.Mitchell, W., 189.Mithoff, R.C., 241.Mitsuwa, T., 279.Mittasch, H., 279.Miyata, A., 133.Mizushima, S., 29, 37.Mizutani, M., 78.Moelwyn-Hughes, E. A., 19, 51, 55.Moffett, E. W., 304.Mohler, H., 290.Mohunta, L. M., 276.Moles, E., 96, 97.Moll, T., 187, 333.Mond, L., 100.Monnier, R., 297.Moore, M. C., 301.186, 332.More, K. R., 377.Moreau, L., 362.Morev. G. H.. 121.Morf,"R., 216.Morgan, G. T., 116, 117, 122, 153.Morgan, W. M., 167.Mori, T., 171.Morino, Y., 29, 37.Morishima, K., 276.Morrell, C. E., 70.Morrell, R. S., 155, 156, 159.Morris, T. N., 140.Morton, A. A., 251.Morton, D. S., 119.Morton, R. A., 43, 195.Moruzzi, G., 331.Moseley, H. W., 301.Moskovitz, B., 299.Mott, N. F., 372, 383, 384, 394, 396.Mott-Smith, L.M., 385.Motz, H., 16.Moureu, C., 247.Moureu, H., 196.Mousseron, M., 145.Mowat, D. M., 335.Bfrazek, S., 162.RiIuckenthaler, H., 99.Muhlbauer, F., 100.Muhlsclilegel, H., 167, 168.Mullenheim, S. von, 194.Miiller, A., 360.Miiller, Adolf, 260, 261, 263.M uller, Alexander, 176.Miiller, E., 129, 132, 138.Muller, H., 316.Muller, R., 139.Muller, W. J., 129.Munster, W., 320.Mukherjee, G. K., 152.Mulliken, R. S., 46, 88, 89.Mumm, E., 281, 284.Munro, H. E., 244.Miirison, C. A., 134.Murlin, J. R., 344.Murphy, G. M., 15, 291, 377.Murray, J. W., 27, 30.Mosley, V. R., 80.Murgulescu, I. G., 298.Nahring, E., 134.Nagai, W., 164.Naidu, R., 382.Narang, K. S., 271, 272.Natta, F. J. van, 160, 161.Naud6, S.M., 98.Naumann, E., 290.Naumann, K., 290.Navez, A. E., 359.Nazarov, I. I., 300.Nazarov, J. N., 250.Neber, M., 342.Neddermeyer, S. H., 393, 401, 405422 INDEX OF AUTHORS’ NAMES.Nedelsky, L., 402.Needham, (Mrs.) D. M., 307.Needham, J., 307, 344.Neese, O., 62, 63.Nehring, K., 350.Nemtzov, M. S., 50.Neogi, P., 152.Neuberg, C., 337.Neubert, F., 138.Neuert, H., 387, 388.Neujmin, H., 53, 253.Neuman, E. W., 88.New, R. G. A., 102, 103.Newburgh, L. H., 344.Newson, H. W., 380, 391.Nicholls, R. V. V., 303.Nichols, M. L., 110.Nicol, H., 349.Nicolas, L., 255.Nielsen, J. R., 30, 36, 36.Nielsen, N., 360, 361, 364.Niesser, K., 329.Nightingale, G. T., 351.Nikawitz, E., 271.Nikolid, R., 201.Nims, L. F., 74.Nishi, T., 256.Nishina, Y., 398, 403.Nixon, I.G., 41.Noack, E., 129.Noda, T., 300.Noddack, (Frau) I., 124, 125, 126,Noddack, W., 124, 125, 126.Nogi, K., 182.Noller, C. R., 154.Nordlund, M., 348.Norkina, S., 270.Norrish, R. G. W., 47, 48, 186, 253,Norton, B. M., 56.Noyes, W. A., 47.Nuernberk, E., 362.372.254.Oatfield, H. J., 266.Obenaus, V. M., 60.Obermann, B., 246.O’Brien, J. R., 328.Occhialini, G. P. S., 399, 402.Ochiai, E., 262.Ogden, G., 18, 20, 21.Ogg, R. A., 52.Ohira, T., 354.Ohle, H., 165, 174, 179, 180, 181.Ohlinger, H., 260.Oka, S., 67.OkBd. A., 298, 317, 320.O&E, B., 298.Oldenberg, O., 92, 259.Oliphsnt, M. L. E., 21, 378, 387.Oliver, E., 192.Olsen, C., 355.Olsson, E., 377.Onsager, L., 60, 63, 64.Onuki, M., 164.Oppenauer, R., 177, 182, 185.Oppenheimer, J.R., 394, 401, 402,Orcutt, I?. S., 347.Ordelt, H., 299, 302.Orbkhov, A., 270, 274, 275.Orlov, J. E., 302.Ornstein, L. S., 36, 92, 97, 371.Orr, W. J. C., 17.Orsino, J. A., 167.Orth, P., 241, 260.Orthmann, W., 63.Ortner, G., 122, 379, 385.Osan, 257.Oserkowsky, J., 357.Osetrova, E. D., 273.Ostern, P., 338, 339, 340.Ott, E., 80.Otto, J., 95.Owen, B. B., 74.Owens, J. S., 92.Ozanne, I. L., 244.Ozawa, S., 352.403.Pacsu, E., 19, 165, 167, 176.Padfield, H. J. H., 255.Pahl, M., 379.Pahle, K., 78.Pai, N. G., 30.Pailer, M., 260.Palmer, A. D., 272.Paneth, F. A., 252.Panizzon, L., 175.Papish, J., 372.Pappenhagen, L. A,, 206.Paranjpe, G. R., 30.Parisi, E., 350.Parker, A.E., 377.Parnas, J. K., 338, 339.Parrish, C. I., 199.Parsons, G. S., 145.Parsons, J. B., 122.Partharasathy, S., 23.Partington, J. R., 116.Paschen, F., 84, 37T.Patat, F., 16, 47, 74.Patnode, W. I., 119.Paton, R. P., 385.Patscheke, G., 133.Patterson, H. S., 95, 97? 295.Patterson, W. J., 341.Patterson, W. S., 142.Patwardhan, H. W., 70.Paul, M. A., 77.Paul, R. E., 50.Pauli, W., 394.Pauling, H., 66.Pauling, L., 38, SO, 88, 103, I l l , 242.Peaoock, D. H., 145INDEX OF AUTHORS’ NAMES. 423Peakes, I,. V., 251.Pearman, S. A., 183.Pearsall, W. H., 353.Pearson, E. A., 311.Pearson, T. G., 14, 48, 252, 254.Pease, R. N., 55.Pedersen, K. O., 67.Pegram, G. B., 393.Peierls, R., 397.Penney, W.G., 87, 88, 144.Penston, N. L., 355.Percival, E. G. V., 177, 182.Perkin, W. H., 279.Perkins, M. E., 308.Perman, E. P., 60.Perrin, F., 395, 402.Pesta, E., 258, 259.Peter, B., 305.Peters, R. A., 328.Petersen, E., 247.Peterson, J. M., 344.Peterson, W. H., 346.Petrenko-Kritschenko, P., 243.Petrey, A. W., 289.Petri, H., 246.Pfeiffer, M., 261.Pfleger, R., 192.Pfotzer, G., 405.Phelps, F. P., 163, 176.Philip, J. C., 66.Philipson, T., 365.Phillips, H., 175.Phillips, M., 307, 308.Phillis, E., 352.Philpot, J. St. L., 328.Piaux, L., 23, 31.Pickering, W., 401, 405.Picon, M., 113.Pielemeier, W. H., 90.Pierce, W. C., 80, 90, 144.Pigman, W., 176.Pikl, J., 267.Pinkard, F. W., 118, 152, 153.Pirie, N. W., 341.Placzek, G., 25, 32, 34, 36.Plant, F., 330.Plant, (Niss) M.M. T., 157.Plotze, E., 63.Pohland, E., 110.Pohlman, G. G., 348.Pohlman, R., 82.Polanyi, M., 16, 18, 20, 21, 49, 52, 66,Pollack, H., 307.Pollard, E. C., 385.Polonovski, M., 164.Poluektov, N. S., 316, 317.Pomonis, C., 255.Pongratz, A., 23, 30, 37, 196.Pontecorvo, B., 386.Popov, B., 53.Porai-Koschitz, A. E., 300.Porret, D., 48, 55.57.Porter, C. W., 145.Porter, J. M., 56.Poulton, E. P., 343.Pramanik, B. N., 365.Pratesi, P., 31.Pmisler, P. W., 308, 309.Preiswerk, P., 392.Prentiss, 8. S., 58.Preston, G. H., 152.Prianischnikov, D ., 35 1.Price, D., 59.Price, H. P., 300.Prileshaeva, N. A., 92.Proca, A., 397.Prochownick, V., 192.Proskurnina, N., 274.Prytherch, J.C., 140.Ptizyn, P., 153.Pugh, W., 120.Pummerer, R., 247.Purcell, R. H., 14.Purves, C. B., 164.Pyman, F. L., 276.Quarrell, A. G., 135.Quastel, J. H., 333, 334.Quiller, B., 82.Rabe, P., 272.Rabi, I. I., 374, 377.Rabinovitsch, E., 92.Rabinovitsch, M., 370.Raether, H., 85.Raisin, C. G., 21.Raitt, R. W., 380.Rajmann, E., 317.Raman, (Sir) C. V., 22.Ramm, W., 22.Ramshorn, K., 363.Randall, M., 59, 60.Rangaramanujam, P., 66.Rank, B., 216.Rank, D. H., 14, 24, 27.Rao, I. R., 23, 24.Raper, R., 150, 270.Rapkine, L., 308.Rapoport, S., 300.Rasetti, F., 386, 391.Rasmussen, E., 377.Rathsburg, H., 314.Rauch, C., 270.Raudnitz, H., 216.RBy, J. N., 271, 272, 276.Rhy, P., 298.Ray, S. N., 309.Rayleigh, (Lord), 380.Raymond, 298.Raymond, A.L., 165, 166, 174.Read, J., 150.Redlich, O., 17, 36, 59, 64.Reese, J., 264424 INDEX OF AUTHORS’ NAMES.Regener, E., 404, 405.Reichardt, H., 251.Reich-Rohrwig, W., 299.Reichstein, T., 170, 177, 182, 184,185, 186, 332.Reid, J. A., 91.Reimers, F., 75.Reincke, R., 356.Reinemund, R., 263.Reissert, 281.Resau, C., 207.Revans, R. W., 92.Reyerson, L. H., 21.Reynolds, R. J. W., 171, 177.Reynolds, (Miss) T. M., 257, 272, 279.Reznikoff, P., 307.Rheineck, A. E., 154.Rice, F. O., 48, 49, 197, 252, 253, 254.Rice, 0. K., 50, 90.Rich, F. V., 167.Richards, T. W., 60, 96.Richards, W. T., 90, 91.Richardson, E. G., 90.Richardson, L. A., 286.Richardson, 0. W., 81.Richardson, R.E., 286.Richter, D., 56.Rideal, E. K., 19, 57, 58, 158.Ridgely, G. H., 121.Riehl, N., 286.Rienacker, G., 300.Rigg, T., 354.Rindal, E., 84, 377.Ritchie, 338.Rittenberg, D., 16.Robbins, R. C., 367.Robertson, G. J., 173, 175.Robertson, J. K., 14.Robertson, J. M., 80, 144.Robertson, (Sir) R., 113.Robinet, P., 145.Robinson, (Mrs.) G. M., 257.Robinson, H. V. W., 145.Robinson, P. L., 57, 124, 125, 254.Robinson, R., 198, 255, 257, 266,Rochow, E. G., 123.Rodowskas, E. L., 48.Rblz, E., 262.Rogers, E., 195.Rogers, H. H., 91.Rohwer, A. G., 301.Rolfe, A. C., 53.Rolla, L., 379.Rollefson, G. K., 65, 56.Roschal, R. B., 300.Rosenblum, S., 381.Rosenfeld, P., 36, 59.Rosenheim, O., 208.Ross, J., 195, 196.Ross, W.F., 47, 253.Rossi, B., 406.Rossini, F. D., 43, 59, 60.272, 276, 279.Rossman, E., 158.Roth, H., 312.Roth, W. A., 124.Rothen, A,, 226.Rothhaas, A., 263.Roughton, F. J. W., 56.Rousset, A., 35.Rouvillois, J., 99.Roy, A. S., 92.Royen, P., 120.Ruark, A. E., 381.Rudge, A. J., 124.Rudy, H., 329, 330.Ruter, R., 305, 308.Ruff, O., 124.Rumbaugh, L. H., 371.Rumpf, P., 243.Rupp, E., 247.Ruschig, H., 209, 326.Rushton, J. H., 139.Russanov, A. K., 289.Rutherford, (Lord), 381, 384, 385,Ruzicka, F. C. J., 228.Ruzicka, L., 146, 207, 208, 209, 211,261, 262, 323, 327.387.SB, A., 300.Sachsse, H., 53.Saenger, H., 117, 153.Sah, P. P. T., 302, 303, 304.Saha, M. N., 396.Sahashi, K., 164.Saito, K., 267.Sakamura, T., 360.Sakata, S., 398.Sakurada, I., 161.Salazar, M.T., 96, 97.Salmon, M. R., 346.Salomon, G., 260, 261.Salow, H., 83.Saltmarsh. (Miss) 0. D., 47, 253. - .Salzberg, P.’ L., 244.Samaras, N. N. T., 64, 71.Samec, M., 187.Samuel, R., 34, 89, 103.Samuels, H., 156.Sanborn, N. H., 139.Sancho, J., 97.Sarge, B. W., 15.Sargent, B. W., 382, 394.Sarver, L. A., 310, 311.Sauerwald, A., 260.Saunders, B. C., 304.Sevanur, K. S., 30.Savel, P., 382, 385, 389.Savib, M. L., 92.Sawyer, J. H., 406.Saxton, B., 74.Scarborough, H. A., 255.Scatchard, G., 58, 7 1.Schafer, H., 202INDEX OF AUTAORS’ NAMES. 425Schiifer, W., 360.Schaffert, R., 82.Schapiro, S., 250.Scharnow, B., 125.Scharrer, K., 355, 357.Scheibe, G., 253.Scheiber, J., 196.Scheibler, H., 200, 201, 202, 203, 204.Schernjakin, F.M., 299.Schenk, P. W., 120.Scherp, H. W., 251.Schetelig, W., 164.Schick, K., 301.Schiedt, B., 163, 179, 332.Schiele, J., 63.Schiff, W., 300.SchildwBchter, H., 291.Schindler, H., 407.Schinle, R., 164, 165, 166, 168.Schintlemeister, J., 379.Schinz, H., 261.Schlenk, W., 248, 249.Schlesinger, H. I., 109.Schlichting, O., 210, 226.Schlinder, F. D., 75.Schlittler, E., 277, 278.Schlosser, C., 257, 319.Schlubach, H. H., 163, 164, 184, 190,Schmid, H., 107.Schmid-Bielenberg, H., 189.Sehmidlin, J., 242.Schmidt, C. L. A., 78, 141.Schmidt, J., 209, 212, 214, 325, 326.Schmidt, 0. T., 170.Schmidt, T., 377.Schmidt, W. B., 296.Schminke, K. H., 60.Schmucker, T., 358.Schoeller, W., 207, 366.Schonberg, A., 246, 247.Schopf, C., 275, 280.Schopp, K., 330.Scholl, E., 256.Schollenberger, C.J., 310.Scholz, C., 267, 268.Scholz, H., 188, 194.Scholz, W., 356.Schopfer, W. H., 366.Schroeder, W. C., 300.Schrodinger, E., 32.Schropp, W., 355, 357.Schtschepkin, G., 387, 392.Schubert, M. P., 308.Schuchardt, W., 337.Schuler, H., 85, 372, 377.Schutze, W., 14, 378.Schuler, 108.Schulman, J. E., 58.Schulman, V. M., 118, 152.Schulten, H., 247.Schultz, R. F., 50, 242, 244.Schumacher, H. J., 55, 57, 82.192.Schunkert, M., 139.Schutz, P. W., 17.Schwabe, K., 129, 132.Schwarte, G., 218, 219.Schwartz, R., 355.Schwarz, K., 13, 21, 318, 319.Schwarz, R., 120, 121.Schwarzenbach, G., 76.Schwenk, E., 207, 325.Schwenker, A,, 64.Schwieger, A., 220.Scott, A.B., 220.Scott, A. F., 60.Scott, R. B., 17.Scott, W. D., 51.Scott, W. W., 311.Scott-Moncrieff, (Miss) R., 257.Searle, N. E., 152.Sears, S. S., 367.Sederholm, P., 128.Segrb, E., 85, 373, 386, 391.Sejersted, J., 137.Seka, R., 30.Sekera, V. C., 303.Selwood, P. W., 17.Bementschenko, V. K., 61.Hementzov, A., 160.Sen, J. N., 270.Sen-Gupta, P. K., 82, 83.Senior, J. K., 152.Serpinski, V. V., 61.Sessler, P., 164.Setoh, S., 133.Beubert, E., 361.Rharratt, E., 118, 153.Shaw, G. T., 50.Shedlovsky, T., 60, 61, 74, 75.Sheldrick, G., 215.Shen, T., 302.Shepherd, M., 294.Sherborne, J. E., 36.Sherman, J., 38, 80, 88.Shibata, K., 343.Shih, C., 303.Shildneck, P.R., 151.Shilov, E. A., 162.Sliinoda, J., 256.Shire, E. S., 378, 387.Shive, J. W., 349, 350.Short, W. F., 202.Shuman, A. C., 372.Shutt, W. J., 133.Sickman, D. V., 50, 254.Sidappa, G. S., 361.Sidgwick, N. V., 38, 45, 75, 88, 101,Sierra, F., 312.Sieverts, A., 124, 125.Signer, R., 188.Simon, E., 334.Simons, J. EL, 115.Simons, L., 35.Sirkar, S. C., 21.102, 106, 111, 114, 195.0 426 INDEX OX AUTHORS’ NAMES.Sitte, K., 395.Skobeltzyn, D., 402.gkolnik, M., 357.Skow, N. A., 120.Slagle, F. B., 80.Slater, J. C., 80.Slotta, K. H., 209, 326.Smakula, A., 51.Small, L. F., 251.Smallwood, H. M., 57.Smekal, A., 24, 32.Smirnova, A. E., 162.Smirnova, T. N., 297.Smith, E. R., 14.Smith, E.W., 255.Smith, F., 177, 182, 183.Smith, G. F., 53, 314.Smith, J. C., 159, 279.Smith, P. T., 97, 98, 369, 371, 387.Smith, S., 218.Smyth, H. D., 371, 387.Smythe, W. R., 370, 371.Snell, A. H., 14.Snell, J. M., 198, 203.Sorensen, J. U., 35, 36.Solheim, W. G., 367.Solomon, E., 49.Soltan, A., 385, 387, 388.Soltzberg, S., 168.Someya, K., 311, 312, 314.Sommerfeld, A,, 106.Sonnekalb, F., 100.Soskina, E. A., 50.Spacu, G., 298, 302.Spacu, P., 298, 302.Splith, E., 257, 258, 259, 260, 266,267, 269, 271, 273, 274, 275, 276,277, 278, 283.Spangler, R. D., 86.Sparmberg, G., 164.Spencer, F., 52.Spencer, J. F., 112.Spinks, J. W. T., 56.Sponer, H., 46, 83.Spong, A. H., 115.Spooner, E. C. R., 138.Squire, C. F., 27.Stacey, M., 182.Stahel, E., 382, 399, 400, 401.Stamm, A.J., 188.Stampfli, J. G., 244.Stanger, D. W., 152.Staudinger, H., 162, 188, 189.Steacie, E. W. R., 20, 49, 50.Steadman, F., 48.Steed, J. G., 289.Steele, B. D., 108.Steffens, C. C., 36.Stegmann, H., 385.Steiger, B., 316.Stein, G., 224, 232, 236.Stein, H., 203.Steiner, H., 13, 19, 21.Steinet, W., 83.Steinke, E. G., 407.Stekol, J. A., 340, 341.Stelling, O., 80.Stenger, V. A., 299.Stepanova, E., 402.Stephens, H. N., 156.Stephenson, A., 247.Stephenson, R. J., 404.Stern, A., 56.Stern, K. G., 308, 329, 330.Stern, O., 374.Stetter, G., 3g5.Stewart, C. P., 335.Stewart, G. W., 85, 86.Stiehler, R. D., 308, 309.Stiller, E. T., 176.Stock, A., 108, 109.Stockdale, J., 127.Stoddart, E.M., 125, 252, 264.Stoher, R., 337.Stoll, A., 218, 237, 238.Stoll, M., 216, 261.Storch, H. H., 50.Storrie, F. R., 303.Stoutenbeek, P., 36.Strada, M., 14.Strafford, N., 216.Strain, R. W. M., 340.Stranathan, R. K., 377.Straumanis, M., 138.Strebeyko, P., 351.Strebinger, R., 301.Striebel, H., 96.Strugger, S., 363.Struyk, A. P., 308.Stschigol, M., 299.Stuart, J. M., 135.Stucklen, H., 253.Stugart, R., 301.Stuhlmann, H., 101.Subrahmanyan, V., 36 1.Suciu, G., 298.Suckfull, F., 167, 169, 170.Suess, H., 19.Sutterlin, W., 109.Sugasawa, S., 275.Sugden, S., 195, 249.Suginome, H., 266.Sullivan, J. J., 197.Sullivan, J. T., 353.Sullivan, M. X., 308.Sun, T. H., 303.Surbotin, W., 118.Suszko, J., 273.Suter, C.M., 304.Suter, E., 218.Sutherland, G. B. B. M., 15, 24, 87.Sutherland, R. O., 74.Sutton, H., 127.Sutton, L. E., 38, 102, 103, 143.Sutton, T. C., 295.Svedberg, T., 187INDEX OB AUTHORS’ NAMES. 427Svirbely, J. L., 309.Swamen, J. C., 91.Swarts, F., 200.Szabo, A. L., 20, 57.SzebellBdy, L., 291, 301, 310, 312.Szego, L., 106.Szent-Gyorgyi, A., 187.Szilard, L., 393, 404.Tiidel, K., 305.Takahashi, T., 216.Talley, S. K., 62.Tamm, I., 85, 396.Tammann, G., 138.Tamura, S., 122.Tananaev, N. A., 316.Tarrant, G. T. P., 397, 399, 400.Tate, J. T., 97, 98, 371.Tatematsu, K., 182.Tauring, A., 302.Taylor, B. S., 251.Taylor, E. G., 64.Taylor, F. M. H., 175.Taylor, H. M., 384.Taylor, H. S., 13, 16, 17, 54, 371.Taylor, P.B., 73.Tchakirian, A., 24.Teece, E. G., 172.Teller, E., 25, 29, 31, 376.Tenniswood, C. R. S., 270.Terenin, A., 56, 253, 254.Tettamanzi, A,, 298, 299.Thal, A., 249.Thaler, H., 305.Tharrer, K., 277, 278.Thatcher, R. W., 301Theorell, H., 331.Thibaud, J., 402, 403.Thiel, H., 174.Thimann, K. V., 359, 360, 363.Thomann, G., 209.Thomas, H. E., 356.Thomas, J. S., 120, 370.Thomas, P. E., 150.Thompson, A., 168.Thompson, A. F., 197.Thompson, D. W., 17.Thompson, H., 215.Thompson, H. W., 56, 52.Thompson, J. C., 155.Thompson, J. J., 302.Thompson, N., 92.Thomsoii, G. P., 134.Thorne, A. M., 23.Thornton, H. G., 347, 349.Tiedjens, V. A., 350.Tillmans, J., 309.Tipson, R. S., 176, 189.Titani, T., 13.TitBica, R., 29.Todd, A.R., 257.Todt, F., 137.Tonnis, B., 361.Tolansky, S., 84, 377.Tomanek, A., 273.Tomimura, K., 277.Tommila, E., 298.Tomonaga, S., 398, 403.Toonder, F. E., 122.Topley, B., 17, 20.Toptschiev, K. S., 273.Torrance, C. C., 88.Toth, G., 189.Toul, F., 162.Tovborg-Jensen, A., 75, 78.Townsend, G. R., 356.Traube, W., 203.Traubenberg, H. R. von, 387.Treiber, R., 170.Triwosch, S., 356.Trogus, C., 161.Tronstad, L., 13, 128, 133, 134, 137.Trtilek, J., 298, 300, 317.Truchet, R., 31.Truesdail, J..H., 365.Trumpy, B., 23, 35, 37.Tsao, J. C. Y., 244.Tsatsas, T., 250.Tschelincev, G. V., 200, 203, 273.Tschernig, K., 323.Tscherning, K., 207.‘I’schervinskaja, L. V., 300.‘rschesche, R., 228, 229, 231, 232,Tschudnowsky, M., 283.Tschugaeff, L., 118.‘rseng, C.L., 300.Tsuda, K., 262.Tulleners, A. J., 163.Turnbull, L. G., 382.Turner, E. E., 151, 152, 283.Turner, J. O., 303.Tutin, J., 81.Twyman, F., 289.‘rzinberg, S. L., 297.235, 328.Udby, O., 71.Ueeda, S., 256.Ulich, H., 66.Ulvin, G. B., 352.TJnderwood, H. W., jun., 303.Ungemach, O., 144.TJngley, C. C., 332.IJre, W., 50.Urey, H. C., 16, 17, 291.Urry, W. D., 60.Vaidya, W. M., 83.Valadares, M. J. N., 382.Valentin, F., 174.Van Atta, C. M., 84, 377.Vanossi, R., 314.Van Veen, A. G., 327428 INDEX OF AUTHORS' NAMES.Vargha, L. von, 165, 173, 174.Varvoglis, G., 250.'Vass, P., 70.Vaubel, R,, 309.Vaughan, A. L., 97, 371.Vaughan, W. E., 50, 162.Vaughan-Jackson, M.W., 80.Vavon, G., 208.Vedder, H., 82.Velculescu, A. J., 297.Vellinger, E., 308.Venkateswaran, S., 35.Vercelloni, A., 337.Verhoek, F. H., 49.Vernon, E., 62.Vernon, W. H. J., 127, 140, 141, 142.Verzhr, F., 340.Vesper, H. G., 55.Vetter, H., 100.Vibe, A., 387, 392.ViBles, P., 149.Vinet, E., 352.Virgili, J. F., 106.Virtanen, A. I., 348, 349, 361.Virtue, R. W., 341.Vleck, J. H. van, 32, 88.Vocke, F., 239, 280.Voge, H. H., 76.Vogel, H. U. von, 122.Vogt, W., 283.Voigt, A., 115.Voigt, W., 71, 79.Volkringer, H., 23, 24.Voll, H., 17.Volqvartz, K., 75, 76.Vorliinder, D., 304.Vorwerk, J., 163, 182.Vosburgh, W. C., 59.Voss, H. E., 207, 324.Voss, J., 200.Vreeswijk, J. A., jun., 371.Wada, I., 301.Wadano, M., 161.Wagenaar, M., 304.Wagner.C.. 64.Wainer; H:, 299.Wagner, 0. H., 105.Wagner-Jauregg, T., 308, 329, 330,331.Wahl, M. H., 17.Wahl, W., 116.Wainer, E., 287.Wakeman, R. L., 23.Walden, G. H., 312, 313, 314.Walden, P., 66.Waldram, J. M., 142.Walker, R. H., 348.Wallace, J. H., 310, 312, 313, 314.Walling, E., 381.Wallis, E. S., 242.Walter, M., 268.Walton, A., 133.Walton, E. T. S., 387, 388, 393.Wanag, G., 194.Wang, A. B., 303.Wang, K. C., 383.Wanka, L., 256.Warburg, O., 331.Ward, A. L., 292.Ward, A. M., 297, 313.Ward, H. K., 85.Wardlaw, W., 117, 118, 152, 153.Warington, K., 356.Warner, T., 364.Warren, B., 122.Warren, B. G., 86.Warren, L. A., 247.Wartiovaara, U., 349.Washburn, E. W., 14.Waterman, H.I., 163.Watson, H. E., 95.Wattiez, M., 354.Watts, H. G., 51.Watts, 0. P., 138.Weber, K., 92, 241.Weeks, M. E., 312.Weibke, F., 126.Weickel, T., 249.Weidenfeld, L., 317.Weidlich, H. A., 215.Weidner, B. V., 76.Weigert, F., 51.Weil, F. J., 239.Weiland, H., 290, 297, 299, 300.Weiler, J., 23, 27, 36.Weisberg, H., 299.Wells, F. B., 150, 284.Wenck, P., 346.Went, F. W., 358, 359, 361.Wenz, A., 163.Werner, T. H., 76.Wertenstein, L., 390.West, E. S., 155.West, S. S., 371.West, W., 24, 137.Westcott, C. H., 392.Western, F., 381.Westmeyer, H., 377.Westphal, K., 224, 236.Westphal, U., 209, 211, 213, 326.Wettstein, A., 209, 326.Wey, H. G. van der, 359,361.Weygand, F., 164, 263, 329, 330, 331.Whaley, F. R., 49.Whalley, F. R., 254.Wheatley, A. H. M., 333.Wheland, G. W., 38, 88.Wheland, H., 242.Whitaker, H., 98.Whitby, L., 139, 142.White, H. E., 377.Whiting, R. E., 22.Whitmore, B. G., 63.Whytlaw-Gray, R., 96, 96, 98, 114'INDEX OF AUTHORS' NAMES. 429Wibaut, J. P., 267, 268.Wiberg, E., 110.Wick, G. C., 396.Wieland, H., 210, 226, 239, 241, 250,Wien, M., 62, 63.Wiener, B., 31.Wiener, M., 262.Wiesenberger, E., 320.Wieth-Knudsen, N., 377.Wiggins, W. R., 297.Wignall, E. W., 230.Wijk, W. R. van, 36, 92.Wilder, F. N., 199.Wildner, F., 304.Wildschut, A. J., 161.Wilke-Dorfurt, E., 105, 125.Wilkinson, (Miss) M. D., 187.Willan, A., 76.Willard, H. H., 302, 311, 312, 313,Williams, E. G., 52.Williams, E. J., 403.Williams, H. G., 163.Williams, J. H., 371.Williams, R. C., 14.Williams, R. J., 365.Williamson, A. T., 18, 47, 53, 54.Willits, C. O., 110.Willstrop, J. W. W., 127.Wilson, B. D., 356.Wilson, C. L., 20, 21, 89.Wilson, C. V., 150, 284.Wilson, E. B., 36, 88.Wilson, G. L., 188.Wilson, P. W., 346, 347.Wilson, R. W., 60.Windaus, A., 207, 210, 218, 219, 220,Windsor, M. M., 99.Winkler, C. A., 49.Winterfeld, K., 270.Wintersberger, K., 95.Winterstein, E., 268.Wintersteiner, O., 209.Wittig, G., 245, 246.Witzinger, R., 243.Wolbling, H., 316.Wojcik, B., 197.Wolfenden, J. H., 18, 20, 54, 62.Wolfes, O., 270.Wolff, K., 55.Wolfrom, M. L., 167, 168.Wolfsohn, G., 371.Wollthan, H., 163.Wood, C. E., 183, 297.279, 280.314.224, 232, 233, 236, 328.Wood, R. W., 27, 92.Woodhead, M., 96.Woods, H. J., 80.Woodward, L. A., 23, 74, 75.Wooster, C. B., 248, 249.Worboys, W. J., 75.Work, R. W., 119, 123.Wormwell, F., 135.Wornam, W. E., 157.Wrede, F., 263.Wrigge, F. W., 124, 125.Wright, A., 353.Wright, C. R., 204.Wright, D. D., 74.Wroncberg, A., 379.Wyatt, G. H., 118, 152, 153.Wynne-Jones, W. F. K., 17, 19, 20,Wynn-Williams, C. E., 381.66, 78.Yakimov, G. I., 162.Yamamoto, Y., 128.Yana.gihara, T., 360.Yen, J. Y., 304.Yoneda, A,, 182.Yoshikawa, H., 275.Yost. D. M.. 36. 38.YoGg, J. T., 50.Young, (Miss) P., 311, 312, 313, 314.Young, R. V., 255.Yuster, S., 21.Zacharias, J. R., 377.Zachariasen, W. H., 40, 143.Zacharov, A., 305.Zappert, R., 315.Zappi, V., 115.Zechmeister, L., 189.Zeeman, P., 368, 377.Zehender, F., 334.Zelinski, N. D., 162.Zener, C., 53.Zervas, L., 164, 171.Ziegert, H., 380.Ziegler, K., 161, 163, 240, 241, 260.Ziegner, H., 200.Ziel, A. van der, 83.Zilva, S. S., 186, 187, 332.Zlotowski, I., 382.Zocher, H., 133.Zondek, B., 324.Zunker, P., 139.Zvenigorodskaja, V. M., 297.Zyw, M., 390

ISSN:0365-6217    

DOI:10.1039/AR9343100409

出版商:RSC    

年代:1934

数据来源: RSC

摘要:

INDEX OF SUBJECTSACETALDEHYDE, thermal decom-Acetic acid, thermodynamic dissoci-Acetoacetic acid, ethyl ester, RamanClaisen reaction with, 200.Acetone, interchange of hydrogenbetween water and, 21.1 : %Acetone 3 : 6-anhydro-a-d-gluco-fixanose, 174.Acetonephosphoric acid, dihydroxy-,formation of, from hexosedi-phosphoric acid, 336.Acetylene, .photobromination of, 55.position of, 49.ation constant of, 74.spectrum of, 196.polymerisation of, 162.interchange of hydrogen betweenwater and, 21.Acetylenedicarboxylic acid, methylester, condensations of, 264,265.Acids, 71.definition of, 72.definition of strength of, 73.aliphatic unsaturated long-chain,carboxylic, ring formation with,Actinodaphne Hookeri, actinodaph-Actinodaphnine, 278.Actinometry, ultra-violet, 56.Act inouranium, half-value period for,Adenylic acid in muscle, 338.Adnatoda vasica, vasicine from, 270.Z-Adonose, 185.Adrenaline, effect of, on root develop-ment, 366.Adsorption, measurement of surfaceequilibria of, 293.Bsculin, 354.ACscuZus, aesculin in leaves of, 354.aZZoBtiocholanic acid, 232.BtioaZhcholan - 1 'I-one, physiologicalactivity of, 208.Btiocholanones, hydroxy-, 209.Aglucones, cardiac, 218.Aldehydes, photodissociation of, 47,154.41.nine from, 278.381.254.reamgents for det'ection of, 302.o-Aldehydophenols, structure of, 41.Aliphatic compounds, 143.long-chain, polymerisation of, 157.Alkaloids, 266.Alkyl halides, stereoisomerism andZ-Allantoin, resolution of, 149.fi-d-Allose, 163.6-Z-Allose, 163.Alloys, radioactive analysis of, 287.d- Altroket ohep tose, 163.jI-Z-Altrose, 163.Aluminium, bombardment of, bya-particles, 390.velocity of solution of, in hydro-chloric acid, 139.determination of, in dyes, 289.Amines, reagents for detection of,determination of, volumetrically,Amino-acids, metabolism of, 340.sulphur-containing, oxidation of,Aminometry, 304.Ammonia, photodecomposition of,54.composition of compound obtainedfrom, with Nessler's reagent,110.determination of, m icrochemically ,319.isoAmyl alcohol as solvent in analysis,301.Anabasis aphylla, alkaloids from,270.Anaemia, pernicious, vitamin-B, intreatment of, 332.Analysis, Raman effect in, 22.by means of dielectric constants,292.by radioactive methods, 286.reagents for spot tests in, 316.fluorescence, 291.gas, 293.gravimetric, adsorption on pre-cipitates in, 285.inorganic quan ti ta t'ive , 320.interferometric, 291.microchemical, 314.organic, 302.structure of, 144.303.304.341.43431 MDEX OF SUBJECTS.Analysis, photoelectric colorimetric,quantitative, on the " gamma "X-ray, 287.spectrographic, 288.ultra-centrifugal, limitation of, 161.volumetric, indicators for, 309.standards for, 295.Androsterone, 207, 323.Angelica root, constituents of, 259.Angelicalact ones, 220.Angelicin, 259.AnhaIamine, structure of, 274.Anhalonidine, structure of, 273.Anhydrides, cyclic, 146.a-, /I-, and w-Anhydrides, polymeric,160.5 : 6-Anhydro-1 : 2-acetone d-gluco-furanose, 174.3 : 5-Anhydro-1 : 2-acetone d-xylose,174.3 : 6 - Anhydro - a - methyl - d - galacto-pyranoside, 174.Anhydro-ouabain hept a -acet ate, 2 37.Anhydro-sugars, 173.Anthocyanins, 257.Aphyllidine, 270.Apocynacem, cardiac poisons from,Aporphine alkaloids, 277.Apple trees, effect of temperatureon nitrogenous nutrition of, 351.cl-Arabo-ascorbic acid, 333.phenylhydrazine derivatives, iso-merism of, with those of 1-ascorbic acid, 181.d- and Z-Arabo-ascorbic acids, 179.Argon, abundance ratio of isotopesArsenic atoms, asymmetric, 150.Arsenic trifluoride, Raman spectrumand structure of, 36.Ascorbic acid, 177.and its homologues, anti-scorbuticactivity of, 186.identity of, with vitamin-C, 332.1-Ascorbic acid, structure of, 177.synthesis of, 182, 184.phenylhydrazine derivatives, iso-merism of, with those of d-arabo-ascorbic acid, 181.Asparagine anhydride, enzymichydrolysis of, 343.Aspergillus, effect of heavy water ongrowth of, 345.Aspergillus niger, auxin in, 360.effect of auxin-B on growth of, 364.Atebrin, 273.Atoms, alternative theory of, 81.ionised, emission spectra of, 83.Atomic nuclei, mechanical and mag-netic moments of, 372.290.scale, 317.218.of, 372.Atomic nuclei, transformations pro-Atomic weights, 94.Auxin in animal organs, 361.Auxin-A, 358.Auxin-B, 364.determination of, 365.Auxins, 358.structure of, 206, 216.Avena colsoptiles, growth renewalin, by auxins, 368.Azides, structure of, 111.Azoimide, structure of, 111.Azomethane, decomposition of, 253.p-L4zoxyanisole, fused, structure of,duced in, by fmt particles, 384.86.Bacillus prodigiogus, pigment from,Bacteria, nodule, fixation of nitrogenBalance, micro - , elec tro -mrtgne t ic,Badum sulphate, precipitated,Bases, 71.263.by, 346..319.adsorption by, 285.definition of, 72.definition of strength of, 73.strong, nature of, 76.Baans, effect of boron on yield of,Benzaldehydes, o-nitro-, photo-Benzene, structure of, 87.Raman effect and symmetry of, 36.and its derivatives, Raman spectraof, 30.interchange of hydrogen betweenwater and, 21.Bcnzophenoneoximes, o-chloro-, iso-meric, 145.Bonzoylacetone, and i t s derivatives,absorption spectra of, 195.Bcnzylme t hylglyoxals , isomeric ,absorption spectra of, 196.(IZ- l-Benzylisoquinoline, resolution of,282.3-Benzyltetrahydroharman, 267.Bonzylxanthyl, reactions of, 251.Borberonic acid, 268.Borgapten, 258.Btryl, helium content of, 380.Boryllium, bombardment of, byneutrons from disintegration of, 404.radioactivity of, 379.detection of, 316.determination of, 289.Biochemistry, animal, 32 3.plant, 346.Bios, 365.Bismuth, determination of, 298.358.isomerisation of, 61.deuterons, 386432 INDEX OF SUBJECTS.Bisnorcholenic acid, physiologicallyactive compounds from, 211.Bis( trimethylbenzoyl)ethanol, 200.Bistriphenylmethyl /3-methyl-d-xvloside, 176.'Z-a-p-Carboxybenzenesulphony1-a-p-tolylthiolethane, resolution of,Bolde; fraqans, boldine from, 278.Boldine, 278.Boletus edulis, auxins in, 360, 365.Boric acid, detection of, 291, 316.Boron, activation of, 393.disintegration of, 388.in nutrition of plants, 357.detection of, 316.Boron hydrides, structure of, 108.Bromine, thermal reactions of, withhydrogen or deuterium, 55.Bufagin, 238.isoBufocholanic acid, 239.Bufotalien, 239.Bufotalin, 239.Bufotenidine, 279.Bufotenine, 279.Bufotoxin, 239.Burettes, micro-, 318.isoButene, polymerisation of, 163.Butin, 256.i8oButyric acid, ethyl ester, con-densation of, with benzaldehyde,204.Cadmium sulphate octahydrate asvolumetric standard, 296.sulphide, colour and crystal struc-ture of, 112.Cadmous compounds, non-existenceof, 112.Czsium, at.wt.of, 370.Calcium, determination of, colori-metrically, 299.Calcium sulphate hemihydrate, 112.Calorimetry, indirect, 343.Carbohydrates, 163.Carbon, at. wt. of, 96.formation of, from fat in the body,valency angles of, 144.activation of, by protons, 393.disintegration of, 388.by neutrons, 386.Carbon suboxide, thermal decom-position of, 57.monoxide, structure of, 102.commercial, analysis of, 295.dioxide, resonance and structureRaman effect and moleculardispersion of supersonic waveE343.of, 38.symmetry of, 35.by, 91.metallic, 99.Carbonyls, structure of, 88.photolysis of, 56.149.Iarnegine, 274.:ells, physiological, effect of heavybllobiose, synthesis of, 164.bllulose, molecular size and weightidentity of, from various sources,water on, 345.of, 188.189.:Wan Su, 238.Jhlorene, 162.Morine, photochemical reactionswith, 55.dispersion of supersonic waves by,91.Xlorine dioxide, photolysis of, 56.Zhlorophyll, 263.Zhlorophyll-a, formula for, 263.2holestano1, structure of, 208.3piCholestano1, structure of, 208.2holestanyl acetates, oxidation of,Zhromium, active and passive, struc-Chromium carbonyls, 99.Chrysene, molecular structure of,Cinchona alkaloids, 272.h-Cinchonine, 273.Cinnmic acid, photohalogenationethyl ester, Claisen synthesis of,208.ture of, 134.passive, activation of, 129.144.of, 55.201 *cis-Cinnamic acids, 145.Cinobufagin, 239.Cinobufotoxin, 239.Citric acid, effect of, on corrosion oftinplate, 140.Claisen reaction, mechanism of, 200.Clover, effect of leaf-hopper on carbo-hydrates in, 353.New Zealand, glucosides of, 354.Clupanodonic acid, 154.Cobalt carbonyls, 101.Coca leaves, dihydroxytropan from,270.Cocaines, 269.Coeroxonones, synthesis of, 256.Colouring matters, 263.Compressibility of electrolytes, 60.Conhydrine, structure of, 269.dl-Coniine, conversion of indolizidineCopper, a-rays from, 380.into, 262.paasivity of, 128.anodic passivity of, 133.atmospheric corrosion of, 141.oxide films on, 134.green patina of, 142.co-ordination compounds of, 116INDEX OFCopper, in pknt chlorosis, 356.detection of, 316.determination of, 297, 301.as mercuri-iodide, 302.Copper ca-rbonyls and nitrosyls, 105.Coprostanol, structure of, 208.epicoprostanol, structure of, 208.Goronilla seeds, coronillin in, 354.Coronillin, 354.Corpus luteum, hormone from, 209.Corrosion of metals, 126.in aqueous solutions, 135.atmospheric, 140.Corydaldine, synthesis of, 276.Cotton plants, distribution of carbo-hydrates in, 352.Counters, tube, for use with penetrat-ing rays, 405.Crops, farm, various sources ofnitrogen for, 350.Crystals, liquid, 85.Cyanogen, emission spectrum of,253.determination of C-C linkageenergy in, 82.Cyanuric triazide, structure of, 11 1.Cyclic compounds, containing nitro-gen, 260.containing oxygen, 266.Cymarin, 219.Cymarose, 2 19.Cystine, metabolism of, 340.Decoic acid, t-hydroxy-, polyestersDelphin, 257.Deoxyeseroline, synthesis of, 267.Dephanthanic acid, 225.Dephanthic acid, 226.Desiccator, micro-vacuum, 320.Desoxoequilenin, structure of, 213.Deuterium (heavy hydrogen), 13.action of y-rays on, 403.liquid and solid, thermal propertiesof, 17.pure, 14.Deuterium iodide, thermal dissoci-ation of, 16.oxide (heavy water), 13.structure of, 86.pure, physical properties of, 17.Raman spectrum of, 27.velocity of reactions in waterand, 19.constancy of, in water, in passingthrough the body, 345.biological action of, 344.determination of, in water, 291.Deuteroacetylene, Ramn spectrumof, 27.Deuteroammonhs, photodecompo-sition of, 64.from, 160.SUB JECTPS.433Deuterobenzene, Raman spectrumDeuterons, 387, 393.Diacetyl, determination of, in butter,Diadenosine-pentaphosphoric acid,Diamond, types of, 113.Diazomethane, decomposition of, 253.methylation with, 194.Dibenzoylethenol, reduction of, 199.cycZoDiela.?ostearic acid, 158.Dielectric constant of electrolytes,use of, in analysis, 292.Digilanides, 218.Digilanidobiose, 2 18.Digitalin, 218.Digitalis, cardiac glucosides from,218.Digitoxigenin, 218, 232.Digitoxose, 218.cis- and trans-Diglycineplatinum, 153.Digoxigenin, 21 8.Digoxin, 218.Dihydro-osthol, synthesis of, 260.15-Diketones, constitution and fissionof, 197.optically active, rate of racemis-ation of, 197.dl-Dilactyldiamide, resolution of, 149.Dimethoxyborine, 109.Dimethyl ether.See Methyl ether.p - Dimethylaminotriphenylcarbinol,reduction products of, 261.1 : 2-Dimethylphenanthrene, 7-hydr-oxy-, synthesis of, 216.1 : 2 - Dimethylcyclopropane - 1 : 2 -dicarboxylic acids, isomeric, 144.s-Dioxaspirohep tane, 282.Dioxan as solvent in dielectricconstant determinations, 292.Dioxidoheterocoerdianthrone, 266.cgcbDipentadecamethylenedi - imine,262.Diphenyl disulphide, radical form-ation by, 247.Diphenylamine as indicator, 310.derivatives as indicators, 312.Diphenylbenzene derivatives, optic-D iphenylbenzidine -viol0 t aa in -Diphenylcarbazide as indicator, 300.Diphenylcarbazone as indicator, 300.Diphenyldihydroglyoxaline disul-phide, radical formation by,247.Diphenylene oxide, dipole momentand structure of, 283.oxide and sulphide, substitutionin, 256.of, 27.290.340.63.&telluride, 252.ally active, 151.dicator, 311434 INDEX OB SUBJEOTS.aa’ - Diphenyltetrahydro - y - pyrones,isomeric, 145.Dipole moment in relation to struc-ture, 80.Dipropionic anhydride, diamino-,enzymic hydrolysis of, 343.2 : 3’ - Dipyridyl- 2’ : 3 - dicarboxylicacid, salts, resolution of, 282.Dipyrrylbenzenes, isomeric , 2 8 2.Diradicals, 245.Dissociation constants, measurementof, 73.Disulphidoheterocoerdianthrone, 256.s-Dithiaspiroheptane, 282.Di-a-thionaphthoyl disulphide,radical formation by, 247.Dithizone, use of, in analysis, 300.CycbDitridecamethyleneimine, 262.Divinylacetylene, polymerisation ofDurene, molecular structure of, 144.Dyes, determination in, of aluminium,162.289.Earths, raze, at.wts. of elements of,Ecgonines, 269.cycZoElzostearic acid, 158.Elzostearic acids, oxidation of, 155.Elaidic acid, synthesis of, 154.Electrodes, antimony sulphide, 296.comparison and indicator, 296.silver halide and sulphide, 296.Electrolysis, microscopic, 320.Electrolytes, 58.dielectric constants of, 63.in solutions, thermal properties of,strong, viscosity of, 62.Electrolytic conductivity a t highfield strengths, 63.Electromagnet for a-particles, 381.Electrons, emission of, in reactions,81.positive. See Positrons.Elements, heavy, radioactivity of,light, radioactivity of, 378.Enols, structure of, 194.Enolisation, degree of, 194.free energy of, 197.Enzymes, effect of heavy water onaction of, 345.Equations for kinetics of reactions, 67.Equilenin, structure of, 214.Erbium, at. wt.of, 370.Ergosterol, structure of, 211.irradiated, vitamin-D from, 57.Eriochrome-cyanin R, detection ofaluminium with, 289.2-Erythro-ascorbic acid; 185.94,370.isotopes of, 368.60.380.dZ-Erythronic acid, resolution of, 149.dZ-Eserethole, synthesis of, 266.Ester condensations, 193.Esters, hydrolysis of, by alkali, 57.Esterification, 53.Ethane, ~-dichloro-, Raman effectand symmetry of, 37.nitro-, neutralisation of, by baryta,in water and heavy water, 20.Ethanes, structure and radical form-ation of, 244.Ethyl ether, decomposition of, 49.iodide, liquid photolysis of, 56.Ethylene, flame spectrum of, 83.velocity of sound in, 91.Ethylidene, free, attempts to pre-Eudyalite, radioactivity of, 380.Extractor, micro-Soxhlet, 320.cyclic, 146.pare, 253.Fats, formation of carbohydratesfrom, in the body, 343.Films, surface potentials of, 57.of aliphatic compounds on aqueoussolutions, 156.air-formed, 127.anodic, 129.Fish, poisons for, 257.Flavan derivatives, 256.Flavins, 329.Flax, lime-induced chlorosis in, 356.Fluorescence, quenching of, by inortFluorescence analysis, 291.Fluorine, at.wt. of, 97.disintegration of, 388.by neutrons, 391.detection of, 316, 317.determination of, in water, 289.Folliculin, effect of, on flowering ofhyacinths, 366.Formaldehyde, absorption spectrumand photochemical decom-position of, 47.Freezing points of uni-univalentsalts, 58.keto-Fructose penta-acetate, 167.aldehydo-Z-Fucose tetra-acetate, 167,Fungi, auxin in, 360.Furfural, determination of, bromo-Furoic acid as volumetric standard,gases, 92.metrically, 304.295.Galactogen, 192.Galactose oxbe, acetylation of, 168.aldehydo-d-Galactose penta-acetate,aldehydo-Galactose, 6-iodo-, tetra-169.acetate, 169INDEX OF SUBJECTS.435ti-Galactoseptanose tetra-acetate, 169.6-~-d-Galactosido-d-glucose, 164.a- Galahep t ose , 1 63.Gallium, and its compounds, 121.Gamabufogenin, 239.Gamabufot oxin, 239.Gas analysis, 293.Gases, dispersion of supersonic wavesin, 90.inert, quenching of fluorescenceby, 92.Germanam, 120.Germanium, and its compounds, 119.Gitoxigenin, 218, 233.isoGi t oxigenin, 2 34.isoGitoxigeninic acid, 234.n- and $80-Gitoxigenones, 234.Gitoxin, 218.isoGluca1, 17 1.Glucals, 170.d-Gluco-ascorbic acid, synthesis of,183.a-d- Glucohep tdose, 1 68.Glucose, mutarotation of, in waterj5-d-Glucose 1 : 2 : 3 : 6-tetra-acetate,Glucosides, plant, 353.5-Glucosidylapigenidin, 257.Glycerides, heat polymerisation of,159.Glycyldiaminopropionic anhydride,enzymic hydrolysis of, 343.Glycylglutaminic anhydride, enzymichydrolysis of, 343.Gold, a-rays from, 380.anodic passivity of, 133.Ururninece, utilisation of amino-acidsGrass, meadow, levan in, 190.Growth substances, 358, 365.sources of error in, 293.and heavy water, 19.172.by, 349.Hsmoglobin, reactivity of, 56.Heart, poisons acting on, 218.Heat, animal, errors in calculationof production of, 343.specific, of electrolytes, 60.Heat of formation in homologousseries, 43.Helium, abundance ratio for isotopesof, 371.in beryl, 380.Hepaflavin, 329.Hepatoflavin, 329.cycloHeptamethyleneimine, prepar-ation of, 261.trans-cycZoHeptane-1 : 2-diol, resolu-tion of, 145.Heterocyclic compounds, 255.diene syntheses of, 264.stereochemistry of, 281.Heteropolar compounds, constitutionand light absorption of, 243.Hexamethylenetetramine, determin-ation of, 304.Hexaphenyle t hane , dissociation of,241.E-Hexolactone, 161.Hibiscus, growth substance in pollenHistidine, 342.dl-Histidine hydrochloride, resolutionHolmium, at.wt. of, 370.Homocyclic compounds, 194.dl-Homolaudanosine, synthesis of,Homomethionine, 341.Homopolar compounds, constitutionand light absorption of, 243.Hormones, effect of, on plant growth,366.of, 359.of, 149.275.animal and vegetable, 206.corpus luteum, 209, 326.follicular, 324.male sexual, 207.plant, 358.secondary sex, 323.sex, origin of, 327.testicular, 323.Hyacinths, effect of folliculin onHydrast ine, stereoisomerides of, 27 6.Hydrazine, structure of, 87.Hydrazobenzene, condensation of,with methyl acetylenedicarb-oxylate, 264.Hydrazoic acid.See Azoimide.Hydrocarbons, distinction between,by reflectivity, 292.aliphatic unsaturated, polymeris-ation of, 162.analysis of, by oxidation on silicagel, 295.Hydrochloric acid, ionisation of,in non-aqueous solvents, 24.solutions, standardisation of, 295.Hydrocinchonidine, 2 72.epiHydrocinchonidine, 2 72.Hydrocinchonine, 272.epiHydrocinchonine, 272.Hydrogen, at.wt. of, 97.isotopes of, nuclear magneticmoments of, 376.separation of, 378.heavy isotope of, 13.See also Deuterium.energy of dissociation of, and itsisotopes, 83.co-ordination of, and theory ofresonance, 37.interchmge of, between differentsubstances, 20.reaction of, with oxygen, 63.flowering of, 366436 INDEX OB SUBJECTS.Hydrogen peroxide, structure of, 87.photodecomposition of, 56.Hydrogenation, investigation of, withhydrogen isotope, 57.Hydroxyl, absorption spectrum of,252.emission spectrum of, 253.Hypophysin, effect of, on rootdevelopment, 366.Imines, cyclic, 260.Imperatoria ostruthium, imperat orinfrom, 257.n- and iso-Imperatorins, 257, 259.Indicators, 309.Indium, and its compounds, 121.Indole alkaloids, 266.Indolizidine, conversion of, into dl-coniine, 262.Inorganic chemistry, 94.Interferometric analysis, 291.Iodine, at.wt. of, 96.Ions, mobility of, 61.oxidation-reduction, 306.ions, spot tests for, 316.electrostatic energy of, in relationactivation ofpassivemetals by, 128.Ionisation of electrolytes in solution,23.Ionisation bursts due to penetratingrays, 407.Irisin, constitution of, 190.Iron, velocity of solution of, inhydrochloric acid, 139.mirrors of, 133.electron-diffraction pattern of ruston, 134.in plant chlorosis, 355.active and passive, structure of,134.determination of, 299.in water, 291.separation of, from beryllium, 299.Iron carbonyls, 100.tetmnitrosyl, 102.Isomerism, geometric, of aliphaticketo-enol, 193.Isoprene, polymerisation of, 163.Isotopes, 368.separation of, 378.abundance ratios for, 371.table of, 369.Ivory nut, rnannans in, 190.to dissociation, 77.compounds, 144.Keto-enols, structure of, 41.Ketones, photodissociation of, 47,254.condensation of, with o-amino-cyclic, 161.benzaldehyde, 262.Ketones, reagents for detection of,Ketonic acids, detection of, 303.p-Ketonic esters, constitution andfission of, 197.Ketoyobyrine, structure of, 268.Ketyls, aliphatic, 250.Kinetic salt effects, 67.Kinetics, chemical, 46.Kynurenic acid, formation of, from302.metallic, 248.tryptophan, 342.iaolactal, 171.Lactic acid, formation of, fromcarbohydrate in muscle, 334.Lactoflavin, 329.with properties like vitamin-B,,164.Laurotetanine, structure of, 277.Lead, determination of, colorimetric-Lettuce, boron-deficiency disease of,Levan, from raffinose and sucrose,Linseed oil, drying of, 154.Liquids,.structure of, 85.analysis, 300.Liquiritigenin, 256.Liquorice root, flavan from, 256.Lithium, disintegration of, 387.solubility of, in unsaturated hydro-carbons, 163.Lithium chloride, viscosity of, inacetone, 62.solutions of, in ethyl, propyl,and butyl alcohols, 86.hydride, solid, photodecompositionof, 55.Litsea citrata, laurotetanine from, 277.Lolium italicurn, effect of potashfertilisers on, 355.Lucerne, effect of leaf-hopper oncarbohydrates in, 353.Lurni-lactoflavin, synthesis of, 263.Lupins, blue and yellow, chlorosisin, 356.Lupin alkaloids, 270./3 -Lupinam, 270.Lupinus albus, auxin in, 359.Luteosterone, 209,326.Lgcoris radiatu, sekisanine in, 276.ally, 299.357.189.absorption of oxygen by, 155.organic, us0 of, as solvents inMagnesium, bombardment of, byvelocity of solution of, in hydro-atmospheric corrosion of, 142.a-part icles, 390.chloric acid, 139IXDEX OEMagnesium, determination of, 297.Magnetic moments, table of, 374.Maize, effect of growth of, on reactionMaize oil, auxin-B in, 365.Malt, auxin-B in, 365.Manganese in plant chlorosis, 355.detection of, 317.determination of, 298.in water, 291.Mannans, ivory-nut, 190.Manninotriose, 164.Manometers, thin-walled tube, 295.Matteucinol, 256.Mercaptides, metallic, reduction of,Mercuric compounds, determinationMercury, photo-oxidation of vapourof media, 350.107.of, 297.of, 55.as iodate, 302.298.determination of, 299.separation and determination of,Metals, electron theory of, 81.solution of, in acids, 138.corrosion of, 126.highly-polished, tarnishing of, 142.passive, activation of, by ions, 128.Metallic3 halides, ultra-violet absorp-tion spectra, of aqueous solutionsof, 67.Methane, structure of, 88.Methionine, oxidation of, 341.Methyl, free, production of, in photo-reaction of, with tellurium, 252.Methyl ether, thermal decompositionof, 49.Methyl-orange as indicator, 314.Methyl-red as indicator, 314.8-Methylbutadiene, a-chloro-, 163.2 - Methylbutanes, 1 - halogeno-,specific rotations of, 149.fi-Methyl-AB-butene, a&dichloro-,163.Methylene, formation of, 253.Methylene-blue, determination of,Methylene carbonates, polymeric,y-Methylfructoside, crystalline, 164.Methylglucopyranoses, 165.Methylglyoxal, formation of, inmuscle, 334.O-Methylmandelamide, urethanefrom, 179.1 O-Methylphenoxarsine-2-carboxylicacid, resolution of, 284.Microanalysis, 3 14.Micro-balance.See under Balance.Micro-burettes. See under Burettes.Microchemical apparatus, 320.decomposition, 48.298.100.SUBJECTS. 437Micrococcus eykmccnii, growth sub-Molecular symmetry and RamanMolecules, restoring forces in, andpolyatomic, theory of " normal "Molybdenum, determination of, 297.Monosaccharides, monomethyl deriv-Muscle, change of carbohydrate intophysical nature of contraction of,poisoning of, with iodoacetic acid,stance in, 366.effect, 32.Raman effect, 24.vibrations of, 88.atives of, 165.lactic acid in, 334.338.339.Naphthalene, structure of, 88, 144.Narcissus tazettu, tazettine from, 276.Narcotine, stereoisomerides of, 276.Nematospora gossypii, growth sub-Neodymium, at.wt. of, 370.Neon, separation of isotopes of, 378.Xeutrino, 84,395.Neutrons, 386, 391.mass of, 404.magnetic and spin moments of,Nickel, oxide films on, 134.anodic passivity of, 133.active and passive, structure of,Nickel carbonyl, preparation of, 108.Nickel steel.See under Steel.Niobium, at. wt. of, 95.Nitrates, determination of, 300.Nitric acid, passivation in, 127.Nitrogen, at. wt. of, 97.heat of atomisation of, 46.fixation of, by nodule bacteria, 346.Nitrogen dioxide (nitric oxide), struc-action of, with metallic carbonyls,stance in, 365.radioactivity of, 379.85.134.ture of, 105.101.oxides, photolysis of, 56.Nitroprussides, 106.Nitrosyls, structure of, 88.metallic, 99.Nitrous acid, detection of, 317.Norbornylane, preparation of, 148.P-aZZoNorcholanic acid, 3-hydroxy-,Norsalsoline, synthesis of, 276.Nuclear moments, 84.Nucleic acids, 176.211.cyclo Oc t amethyleneimine, 2 62.cycZoOctanone thioisooxime, 261438 INDEX OF SUBJECTS.(Estriol, determination of, in urine,325.(Estrone, 324.Oleic acid, synthesis of, 154.Optical activity, 86.Oreoselone, 257.Organs, animal, auxin in, 361.Organic analysis, 302.Organo -metallic compounds, complex,Osmium, at.wt. of, 94.Osmium tetroxide, absorption spec-trumof, 82.Osthol, 258.Ostruthin, 259.Ostruthol, 259.Ouabagenin, 219, 237.Oxalic acid, potassium cobalt salt,optical activity of, 87.Oximes, ring formation with, 41.Oxine, use of, in analysis, 297.Oxygen, at. wt. of, 98.polarisation molecule of, 83.valency angles of, 143.use of isotope of, in investigation ofester hydrolysis, 57.abundance ratio of isotopes of, 370.reaction of, with hydrogen, 53..determination of, in gas mixtures,Oxypeucedanin, 258.Ozone, photolysis of, 56.structure of, 214.determination of, in urine, 325.calculation of, 148.chemistry, 143.compounds, spot tests for, 315.152.294.Pachycarpine, 270.Paints, struc$xe of, !,57.Paint films, bloom of, 156.Palladium, co-ordination compoundsdetermination of, 297, 299, 316.Palladium ammines, 153.Palladium bis-antibenzylmethyl di-p-Palladodiammines, 152.Panthothenic acid, 365.Paraffins, heats of formation of, 44.a-Particles, bombardment by, 389.of, 117, 118.oxime, 153.transformations in nuclei by,385.emission of, 381.8-Particles, emission of, 382.theory of disintegration by, 394.Passivity, optical investigation of,and film formation, 127.anodic, 129.133.Pears, exanthema in, due t o copperdeficiency, 357.Pecan rosette due to copper de-Peganine, 271.Peganum harmla, alkaloids from, 271.Pellagra, prevention of, by vitamin-&,331.Pellotine, structure of, 273.Pentaerythrit oldipyruvic acid,optical activity of, 87.Pentocystine, 341.Peptides, hydrolysis of, by enzymes,342.Periodic acid, structure of, 116.isoPeriplogenic acid, 230.Periplogenin, 219, 230.Permanganates, indicators for titra-tion with, 312.Per-rhenic acid, salts, 125.Peucedanin, 257.Phenanthridine alkaloids, 276.o-Phenanthroline ferrous salts asPhenol, determination of, in water,Phenol, dinitro-, dissociation con-Phenoxarsinecarboxylic acid, resolu-Phenyl dichloroiodide, structure of,ethers, rates of chlorination of, 52.Phen yle t h ylisoprop ylgermaniumbromide, optically active, 121.Js-Phenyl- a - 1 - hydroxyhydrindene-2-propionic acids, isomeric, 145.Phenylxanthyl, reactions of, 25 1.Phosphagen, hydrolysis and re-synthesis of, in muscle, 337.Phosphoglyceric acid, degradation of,to pyruvic acid, 337.Phosphorus pentachloride, structureof, 115.Photographs, cloud-chamber, ofpenetrating rays, 405.Phthalocyanine, 146, 2 64.Phycomyces blalcesleeanus, acceler-ation of growth of, by substancefrom wheat, 366.a-Picoline, formation of, from hexa-methyleneimine, 262.Picric acid, dissociation constant of,74.determination of, 298, 305.Picrolonic acid, use of, in analysis,Pipettes, capillary, 317.Plants, growth substances in, 358.auxins in, 359.cell elongation and metabolism in,in relation to auxin-A, 363.geotropism, phototropism, andelectrotropism in, in relation toauxin-A, 361.ficiency, 357.indicators, 313.291.stant of, 74.tion of, 151.115.299INDEX OF SUBJECTS.439PIants, boron in nutrition of, 357.carbohydrates in, 352.copper in relation to chlorosis in,effect of hormones on growth of,iron and manganese in relation tonitrogen nutrition and metabolismpotassium in nutrition of, 354.higher, biochemistry of, 349.356.366.chlorosis of, 355.in, 349.Plant diseases, effect of, on carbo-Plant glucosides, 353.Plant roots, carbohydrate content of,Plasmoquin, 273.Platinum, co-ordination compoundsof, 116.Platinum ammines, 153.Platotetrammines, isomeric, 153.Pleochroic haloes, 382.Poisons, cardiac, 218.plant, for fish, 257.toad, 238, 279.of aliphatic long-chain compounds,condensation, 160.Polymethylene compounds, cyclic,146.Polysaccharides, molecular size of,187.Positrons, 402.Potassium, radioactivity of, 378.hydrate content, 353.353.Pollen, growth substance in, 359.Polymerisation, acceleration of, 50.157.in plant nutrition, 355.detection of, 317.determination of, 298.Potassium alloy with sodium, emissionof electrons by, 81.Potassium mperouide, structure of,88.Potato plants, effect of leaf-roll oncarbohydrates in, 353.Potent ids, oxidation-reduc tion, 305.Precipitates, adsorption by, 285.Pregnanediol, luteosterone from,aZZoPregnanol-20-one, 21 3.Prodigiosine, 263.isoPropy1 alcohol as solvent inanalysis, 301.isopropyl mercaptan, Raman spec-trum of, 28.2 : 3-isoPropylidene-a - d - fructofuran-ose, 164.Proscillaridin A, 219.Proteins, possibility of diketopiper-azines in, 342.digestion of layers of, by enzymes,58.212.Protium, at.wt. of, 98.Protoactiniim, separation and puri-Protoglucal, 171.Protons, 387, 393.Psicaine, 269.Pueraria hirsuta, kzmpferol rhamno-side from, 354.Pj’ridine, condensation of, withmethyl acetylenedicarboxylate,265.Pyridine, 2-amino-, use of, in analysis,300.Pyrogallol, use of, in analysis, 299.Pyruvic acid, formation of, fromphosphoglyceric acid, 337.fication of, 384.magnetic moment of, 85.Quantum mechanics, 80.Quinaldinic acid, use of, in analysis,298.Qirinoline, 8-hydroxy-, use of, andits derivatives, in analysis,296.Qirinoline alkaloids, 270.isoQuinoline alkaloids, 273.Quinoline dicyanides, 281.Radicals, free, 80, 240.long-life, 240.short-life, 251.Radioactivity, 368.containing univalent sulphur, 247.use of, in analysis, 286.artificial, emission of positrons in,383, 402.Radium-C’ and -D, half-value periodsfor, 381.Raman effect, 21.Rays, penetrating, 404.y-Rays,.382.vibrational frequencies in, 25.emission of, in nuclear disin-hard, anomalous absorption of,tegrations, 388.397.X -Rays, analysis by means of, 287.apparatus for, 287.Reactions, normal and slow, insolution, 51.Reductic acid, 185.Reductone, 186.Renoflavin, 330.Rosins, structure of, 167.Resonance, theory of, and co-ordin-Rhenium compounds, 123.Rhizobia, fixation of nitrogen by,346.Rhizopus minus, auxin in, 360.Ribose, 176.ation of hydrogen, 37,40440 INDEX OERoses, effect of “blind wood” oncarbohydrates in, 353.Rubianic acid, use of, for deter-mination of platinum metals,316.Rubidium, radioactivity of, 378.Rubrene, photo-oxidation of, 48.Rubrenes, irradiated, absorption ofRutabagas, effect of “ dark centre ”oxygen by, 246.on carbohydrates in, 353.Salamanders, samandarine from,Salireposide, 354.Salsola Richteri, salsoline from, 274.Salsoline, 274.Salt effect, primary, 70.Salt hydrates, structure of, 89.Salts, uni-univalent, f.p.of, 58.Salvia patens, anthocyanin in, 257.Samandarine, 280.Samarium, isotopes of, 378.Sarmentogenin, 219.Scilla, fructoside from, 354.Scillabiose, 219.Scillaren A , 218.Scillaridin, 2 19.Scillaridin A , 219, 237.Sekisanine, 276.Selenium, at. wt. of, 370.detection of, 317.Septanoses, 169.Silica gel, platinised, use of, in gasanalysis, 295.Silver halides, photolysis of, 56.Snails, galactogen in, 192.Sodium, at. wt. of, 95.Sodium alloy with potassium,emission of electrons by, 81.Sodium iodide, viscosity of, in ethylalcohol, 62.Soils, diffusion of nodule nitrogeninto, 349.peat, treatment of, with copper,356.Solutions, aqueous, corrosion in,135.Solvents, influence of, on ionisationof electrolytes, 66.“ aprotic,” 79.Solvent effect, influence of, on degreeof enolisation, 196.Sophocarpine, 270.Sophoridine, 270.Z-Sorbose, preparation of, 184.Sorghum, effect of growth of, onreaction of media, 351.Sorghum vulgare, gluuosides in, 353.Soya beans, stigmasterol in, 210.280.secondary, 71.radioactivity of, 379.IUBJEOTS.n- and iso-Sparteines, 270.Spectra, emission, of ionised atoms,infra-red and Raman, relation of,visual flame, analysis by means of,Spectrographic analysis, 288.Spectroscopy, physico-chemicalapplications of, 81.Spirogyra nitida, effect of heavy wateron, 345.Spot tests, 314.Squills, glucosides of, 218.Stachyose, 164.Starch, thermal degradation of,in plants, 352.Steel, mild, effect of non-metallicinclusions on corrosion of, 137.nickel, resistance of, to sea water,137.Stereochemistry of aliphatic com-pounds, 143.Stigmasterol, structure of, 210.Stilbene, photo-isomerisation of, 51.a-isostrophanthic acid, 222.a-isostrophanthidic acid, 222.Strophanthidin, 219, 220.formula for, 227.isostrophanthidin, 221.#-Strophanthidin, 223.a-zsostrophanthidinic acid, 222.Strophanthus, cardiac glucosides of,Strychnine, 279.Styphnic acid as reagent in organicStyrene, detection of, in ethyl-Sucrose, inversion of, in water andSugars, migration of acyl groups in,83.25.288.192.degradation of, 326.219.determination of, 304.analysis, 303.benzene, 23.heavy water, 19.172.action of pyridine on, 170.acetylation of oximes of, 168.cyclic and open-chain, distinctionbetween acetates of, 168.open-chain, 166.detection of, 304.determination of, microchemically,319.Sugar cane, sugar and starch form-ation in, 352.Sulphonyl groups, acidifying actionof, 193.Sulphosalicylic acid, use of, inanalysis, 299.Sulphur, valency angles of, 143.Sulphur chlorides, 114.fluorides, 114INDEX OF SURJECTS.441Sulphur bzduorides, Raman effectand structure of, 36.Supersonic waves, 90.Surface tension of dilute electrolyticsolutions, 64.Tantalum, at. wt. of, 95.Tazettine, 276.Tellurium, at. wt. of, 370.rn reagent for detection of freemethyl, 252.detection of, 317.Tetraimamyla,mmonium nitrate, con-ductivity of, in dioxm-watermixtures, 65.Tetra-anhydro-ouabain, 237.1 : 3 : 4 : 6-Tetrabenzoyl fructose,164.Tetraethylammonium picrate, vis-cosity of, in nitrobenzene, 62.Tetrahydro -@-carboline, 2 67.Tetrahydroharman, 267.Tetrahydroyobyrine, structure of,268.Tetrakisdiphenylyldi - (tert.- butyl-acetylenyl)ethane, 244.Tetrakisdiphenylyldi - tert. - butyl-ethane, 245.Te trame t hy 1 me thylgalac t osep t -anoside, 169.Thallium, separation of, by etherextraction, 301.Thermostat, air, 141.Thianthren, dipole moment andstructure of, 283.dl-@-Thiodipropionic acid, resolutionof, 149.Thiyls, 248.Thorium, half-value period for, 381.Thyreoidin, effect of, on plantThyroxine, effect of, on leaf develop-Tin, and its alloys, corrosion of, byTinplate, corrosion of, 139.Toads, poisons from, 238, 279.Tobacco plants, effect of virus oncarbohydrates in, 353.N-p-Toluenesulphonylhexamethyl-eneimine, 260.Tolyl ethers, rates of chlorination of,52.p-Tolylbenzylethyl-n-propyl-arsonium iodide, resolution of,150.Tomato plants, ammonia and nitrate’intake by, 349.Transport numbers, measurement of,by moving-boundary method,61.B@-Trehalose, 164.growth, 366.ment, 366.tap water, 137.Tr ikobutene, 163.Triethylamine, trihydroxy-, w e of,Tr iethylenediaminocadmimn chloride,Triglycerides, structure of, 169.Triketones, isomeric, 199.Tr imet hylindium , 1 2 3.Trime thylrhenium, 125.s-Triphenylbenzene, molecular shapoTriphenylmethane dyes as indicatorsTriphenylmethyl, 242.formation of, 251.reactions of, 251.Triphenylmethyl a-methyl-Z-fucoside,Tr iphenylme thylpyrophosphoric acid,Tropine alkaloids, “ open,” 269.Tryptophan, 341.T u g oil, gelation of, 157.Tungsten carbonyls, 99.in analysis, 298.optical activation of, 152.of, 144.for permanganate, 312.176.ethyl esters, isomeric, 151.Uranium-I and JI, half-value periodsUranium-X,, limit for @particles of,Urine, auxin in, 361.Uaarigenin, 219, 230.for, 381.382.male, oestrone in, 324.Vctlency, electron theory of, 89.and molecular structure, 87.Vdonia rnacrophysa,.auxin in, 361.Vmadium, determination of, 297.Varnish films, “ bloom ” of, 156.Varnishes, structure of, 157.Vasicine, 270.isoVasicine, 271.Volocity of reaction, 46.equations for, 67.in unimolecular films, 57.in water and heavy water, 19.Vibrational frequency in relation toVines, accumulation of sugar in,Vinylacetylene, preparation andViscosity of strong electrolytes, 62.Vitamin-B,, 327.Vitamin-B,, 329.Vitamin-0, 332.Vitamin-D, formation of, from irradi-Volumetric analysis, indicators for,isotopes, 26.352.polymerisation of, 162.determination of, 309.ated ergosterol, 57.309.standards for, 296442 INDEX OF SUBJECTS.Water, structure of, 86.Raman spectrum of, 24.heavy.See Deuterium oxide.natural, ratio of hydrogen todetermination in, of fluorine, 289.deuterium in, 13.of iron, manganese, and phenol,291. 4Water lilies, tropical, boron in relationto pollen of, 358.Wave mechanics, 80.Wheat, effect of “rust” on carbo-hydrates in, 353.Xan t hine derivatives , spectrographicdetermination of substitution in,177.Xylan, structure of, 191.m-Xylene, detection of, in op-mix-tures, 23.Yeast, auxin in, 361.effect of auxin-B on regenerationof, 364.Yobyrine, structure of, 268.Yohimbine, 267.Zea mais, auxin in roots of, 359.Zinc, radioactivity of, 380.velocity of solution of, in acids, 138.oxide films on, 135.dome formation in corrosion of,determination of, 297.Zirconium sulphides, 113.135

ISSN:0365-6217    

DOI:10.1039/AR9343100430

出版商:RSC    

年代:1934

数据来源: RSC