摘要:

ARC-WELDINGHANDBOOKbyKARL MELLERContentsI. Introduction. 11. Welding Processes (a) Carbon Arc(b) Metal Arc. 111. Physical Nature of the Arc. IV.Welding Equipment and *Accessories. (a) Direct-CurrentWelding (b) Alternating-Current Welding (c) Maintenance ofWelding Machines (d) Accessories (e) Automatic WeldingMachines. V. Welding Electrodes (a) Electrodes for MetalArc Welding (b) Carbon Electrodes for Carbon Arc Welding. VI.Welding of Steel (a) Parent Material (b) Types of WeldedJoints (c) Practical Welding (d) Strength of Welded Joints (e)Cost of Electric Arc Welding. VII. Cast Iron and Cast SteelWelding (a) General Observations on the Welding of Cast Iron(b) Cold Welding of Cast Iron (c) Hot Welding of Cast Iron(d) Welding of Cast Steel.VIII. Arc Welding of Non-Ferrous Metals (a) Aluminium and its Alloys (b) Copper and itsAlloys (c) Nickel and its Alloys. IX. Testing Welded Joints(a) Non-Destructive Tests (b) Tests to Destruction.The object of this handbook is to enable the operator tounderstand the processes involved in arc-welding, and toutilise the results of the latest research in improving and simplify-ing his work. The welding engineer will derive considerableinterest from the descriptions of plant and equipment, and moreespecially from those pages devoted to the choice and testing ofelectrodes. Owners of small shops, who are frequently thrownentirely upon their own resources, will find invaluable informationand advice in this handbook.Crown 8vo. 200 pp. 83 illustrations. 8'6 netHUTCHINSON'S SCIENTIFIC & TECHNICAL PUBLICATIONS34 PATERNOSTER Row, LONDON, E.C.4Telegraphic Address :'' Casthermo, Smith,London."Telephone :Terminus 2030.The mark of precision and eficiency.BRITISH MADETHROUGHOUTIf you use heat-it pays to measure it accuratelyB. BLACK & SON, LTD.1, Green Terrace, Rosebery Avenue,LONDON, E.C.1Thermometer Manufacturers(MERCURY IN GLASS T Y P E )Original Makers of the Improved, Gas-filled, Permanent Thermomekrs forLaboratory and Industrial Processes.Standard Thermometers of the highestaccuracy covering over a range fromminus zoo to plus 520° C.The black filling-in etchings will resistall solvents with the exception of thosethat attack the glass itself.The National Physical LaboratoryCertificates supplied, with any type.Of all the principal Scient#ic Instrument and LaboratoryApparatus Man ufac tur e n .vMODERNRUBBERCHEMISTRYA comprehensive survey of thebehaviour of rubber and latex in everyphase of their commercial applicationsby HARRY BARRONPh.D., B.Sc., A.I.C., A.I.R.I.Con ten t sCh.I. History of Rubber-Ch. 11. Sources of Rubber-Ch. 111.Latex-Ch. IV. Properties of Latex-Ch. V. CommercialRubber-Ch. VI. Theory of Coagulation-Ch. VII. Machineryand Processes-Ch. VIII. Physical Properties of Rubber-Ch. IX. Chemical Properties of Rubber-Ch. X. Mastication-Ch. XI. Chemical Composition of Rubber-Ch. XII. Structureof Rubber-Ch. XIII. Vulcanisation-Ch. XIV. Testing ofRubber-Ch.XV. Compounding of Rubber-Ch. XVI.Accelerators-Ch. XVII. Ageing of Rubber-Ch. XVIII.Vulcanisation Theory-Ch. XIX. Accelerator and AntioxidantTheory-Ch. XX. Reinforcement of Rubber-Ch. XXI.Reclaimed Rubber-Ch. XXII. Hard Rubber-Ch. XXIII.Direct Use of Latex-Ch. XXIV. Synthetic Rubber-Ch. XXV.Analysis of Rubber.Demy 8v0, 342pp., 70 illustrations. 18’- netHUTCHINSON’S SCIENTIFIC & TECHNICAL PUBLICATIONS34 PATERNOSTER Row, LONDON, E.C.4vi Just PublishedSYSTEMATIC ORGANIC CHEMISTRYModern Methods of Preparation and EstimationW. M. CUMMINC, D.Sc., I . V. HOPPER, Ph.D., and T. S. WHEELER, Ph.D.Third Edition. Demy 8vo. XXVl + 547 pages. 25/- netATOMIC THEORY: AN ELEMENTARY EXPOSITIONA. HAAS, Ph.D. New Edition revised byW. A.CASQARlDemy 8vo Many Illustrations 15'- netTranslated by T. VERSCHOYLE.PHYSICAL CHEMISTRYJOHN ECGERT. 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ISSN:0365-6217    

DOI:10.1039/AR93734FP001

出版商:RSC    

年代:1937

数据来源: RSC

摘要:

ANNUAL REPORTSON THEPROGRESS OF CHEMISTRY.RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.DURING the year the number of types and examples of nuclear trans-formations known has been greatly increased by the use of artificialsources of particles and quanta more energetic than those fromnatural radioactive sources. The intensity, also, of the artificialsources is many times greater than that from the biggest naturalsources. a-Particles from the cyclotron have facilitated the ob-servation of a-induced radioactivity in the heavier elements. Withartificial sources of very energetic neutrons and y-rays it has beenfound that the expulsion of a neutron by y-ray or neutron impactis a very general possibility among the elements. The nucleartransmutations known up to the middle of 1937 are discussed veryfully in a review by H.A. Bethe and M. S. Livingston.1The theoretical treatment of the nucleus regards it as made upof neutrons and protons, and the application of quantum theoryto nuclear problems,. with various approximations, has gone onsteadily.2Work on the penetrating radiation has been greatly helped bythe development of the quantum theory of fast electrons. It seemsthat the less penetrating part of the rays consists of electrons whichfit in with the theory, and this can therefore explain most of thecosmic ray phenomena in the atmosphere. The nature of the morepenetrating rays is not yet clear, and a great deal of experimentalattention is now focused on this part of the radiation.ISOTOPIC CONSTITUTION OF THE ELEMENTS.P.W. Aston has made a careful set of comparisons to establishthe isotopic mass of 12C, and finds 12.00355 & 0.00015 for this im-portant mass. He has also made new and accurate mass determin-Rev. Mod. Physics, 1937, 9, 246.H. A. Bethe, ibid., 1936, 8, 82; 1937, 9, 69.Nature, 1937, 139, 6228 RADIOACTIVITY AND SUB- ATOMIC PHENOMENA.ations for 78* 82* 849 86Kr and 129* 132Xe.4 J. Mattauch has madeaccurate determinations of the masses of 86* 87Sr and shown byanalysis of a specimen of strontium obtained from a mica rich inrubidium that 87Sr is produced by the p-ray transformation of thatelement. A. J. Dempster has confirmed Aston's suggestionthat neodymium has isotopes a t 148, 150 and established theexistence of 180W.7 A. 0.Nier has designed a new mass spectro-meter for the purpose of making accurate determinations of relativeabundances of isotopes. The elements Hg, Xe, Kr, Be, I, As, andCs were investigated. No new isotopes were found, but theabundance ratios for 196. 198, 199. 200, 201, 202, 204Hg, 124, 126, 128, 129, 130,131. 132, 134, 136Xe, 78, 80, 82. 83, 84, 86Kr were determined. 8Be was notfound with a detection limit of 1 in 100,000, and caesium, arsenic,and iodine were shown to be simple elements to about this limit.The abundance ratios were also determined for 184, 186s 187, 188. lgo-lg20s ; the 187 isotope was definitely found-it constitutes an iso-baric pair of adjacent elements with ls7Re.The methods available for the separation of isotopes have beendiscussed; l o the diffusion method of separation has been appliedto argon l1 and a chemical method to lithium.12NUCLEAR MOMENTS AND SPINS.The magnetic moment of the proton has been measured by I.Estermann, 0.C. Simpson, and 0. Stern,13 using the deflection in aninhomogeneous field of molecular beams of H, and HD. The valueobtained is 2.46 nuclear magnetons & 3%. The nuclear spin of6Li has been shown to be l.14 An atomic-beam method has beenused by H. C. Torrey l5 to obtain the sign of the magnetic momentof 3sK, which is found to be positive; Le., it has the spin direction.This .ciontradicts the result obtained from hyperfine structure ofspectral lines.16 The atomic-beam method gives the positivesign for 7Li, B5Rb, g7Rb, and 133Cs.17Nature, 1937, 140, 149.Physical Rev., 1937, [ii], 51, 289.Naturwiss., 1937, 25, 170, 180.irbid., 52, 1074.Idem, ibid., p.885. * Ibid., p. 933.lo G. Champetier, Bull. SOC. chim., 1936, [v], 3, 1701 ; Nature, 1937,139, 38.l1 H. Kopfermann and H. Kriiger, 2. PhysiE, 1937, 108, 389; H. Barwickl2 G. N. Lewis and R. T. Mulacdonald, J. Amer. Chem. Soc., 1936, 58, 2519.lS Physical Rev., 1937, [ii], 52, 535.l4 J. H. Manley and S. Millman, ibid., 51, 19.l5 Ibid., p. 501.l6 D. A. Jackson and H. Kuhn, Nature, 1936, 137, 107; R. A. Fisher,l7 S. Millman and J. R. Zacharias, ibid., p. 1049.and W. Schiitze, ibid., p. 395.Physical Rev., 1937, [ii], 51, 887BRADDICK. 9The hyperfine structure of barium lines leads to a value $ forthe spin of the odd isotopes.l*THE GENERAL THEORY OF THE NUCLEUS.The nucleus consisting of protons and neutrons may be treatedtheoretically 19 by an approximate wave-mechanical method anal-ogous to that introduced by Hartree for the extranuclear electrons.The method consists essentially in treating each particle as anindividual in a common field, and may be expected to be a reason-able approximation for the lightest nuclei.The model leads tothe existence of neutron and proton shells and to the appearanceof periodic nuclear properties. In particular, the binding energiesof nuclei show periodicities of the type predicted. Although thewave-functions used do not correspond to pre-formed a-particlesin the nuclei, the energies exhibit a four-shell structure.20 Using theresults of Feenberg and Wigner for the wave-functions of the par-ticles, M.E. Rose and H. A. Bethe 21 have calculated the nuclearspins and magnetic moments of the lightest nuclei. The valueof the spin for 'Li, which can be compared with experiment, is givencorrectly by the theory.This kind of approximation is useless when applied to nucleardynamics, particularly in the case of the heavier nuclei.22 On accountof the short range and high intensity of the forces between nuclearparticles, a particle which strikes the nucleus dissipates its energyamong the nuclear particles. Each particle of the " compoundnucleus " will have some energy, but none will have sufficient energyto escape from the rest, so that the compound nucleus will remainin an excited state until the energy is " by accident " concentratedon one particle and allows it to escape.There are a number ofenergy levels for the compound nuclei ; in light elements the spacingis of the order of hundreds of kv., but in heavy elements it is of theorder of a few volts. These energy levels are responsible for thephenomenon of resonance, e.g., in the capture of protons (see p. 13)and of slow neutrons (see p. 16), for the probability of formationof a compound nucleus is specially high when the energy of thesystem which includes the bombarding particle is nearly equal tothe energy of one of the levels of the compound nucleus.18 A. N. Benson and R. A. Sawyer, Physical Rev., 1937, [ii], 52,1Q H. A. Bethe and R.F. Bacher, Rev. Mod. Physics, 1936, 8, 82.20 E. Feenberg and E. Wigner, Physical Rev., 1937, [ii], 51, 95.21 Ibid., p. 205.22 N. Bohr, Nature, 1936, 137, 344; H. A. Bethe, Rev. Mod. Physics,1127.1937, 9, 6910 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.NUCLEAR DISINTEGRATION BY a-PARTICLES.(a; p) and (a; n) Transformations in the Lighter Elements.-Evidence was found for a small yield in the reactionfH + :He +- iH + in + ;He with thorium-C' a-parti~les.~~ Anattempt to detect protons from 6* iLi + :He --+ 's1;Be + ,H usingradium-C' a-particles gave a null result, though the reverse reactionis well known in the case of 6Li.24 The protons from the reactionlOB(a ; p)i3C were examined,25 since the most energetic group previ-ously known (3.3 M.E.V.) did not carry off the energy to be expectedfrom the nuclear masses.A weak group a t 4.7 M.E.V. was found,in agreement with the masses, but it seems that the production ofan excited final nucleus and a 3.3 M.E.V. proton is far more probable.The probability of the reactions 27Az(ol ; n)30P and 26Mg(a ; p)28A1has been studied as a function of the a-particle energy.26 By com-parison with the excitation function of the reaction 27Al( a ; p)30Si,27Waring and Chang conclude that the resonance observed is corre-lated with easy escape of the neutron or proton rather than witheasy penetration of the a-particle barrier. This is in harmony withBohr's view of the nuclear reaction proceeding by the instantaneousformation and disintegration of an intermediate nucleus.28Experiments have been made on the (a ; p ) transmutation of neon,calcium, and argon;29 the first two gave protons with thorium-C'a-particles, but only one group was detected.It appears that 20Nedoes not fit into the series scheme of 24Mg, 28Si, 32S, which givegroups corresponding to excited states of the product nuclei Meringby roughly 1 M.E.V. Pollard and Brasefield give a table in whichthe energies for (E; p ) reactions are used to interpolate betweennuclear masses obtained by the mass spectrograph and in this waymost of the nuclear masses between %e and 40A are determined.E. Pollard, H. L. Schultz, and G . Brubaker 30 found that chlorine andargon gave a considerable yield of neutrons under a-particle bom-bardment. The suggested reactions are 37Cl(a; p)@K andMA(.; p)43Ca.On the assumption that penetration by thea-particles takes place over the top of the potential barrier, thenuclear radii were calculated as 6.1 x cm. for chlorine, and7.3 x 10-13 cm. for argon.23 H. L. Schultz, Physical Rev., 1937, [ii], 51, 1023.24 W. G. Shepherd, R. 0. Haxby, and E. L. Hill, ibid., 52, 674.25 G. Brubaker and E. Pollard, ibid., 51, 1013.2% J. R. S. Warhg and W. Y . Chang, Proc. Roy. SOC., 1936, A , 157, 652;W. Y. Chang and A. Szalay, ibid., 1937, A, 159, 72.27 J. Chadwick and J. R. Constable, ibid., 1932, A, 135, 48; W. R. Kume,Physical Rev., 1937, [ii], 52, 266.2s E. Pollard and C. J. Brasefield, Physical Rev., 1937, [ii], 51, 8.3O Ibid., p. 140.28 See this vol., p.9BRADDICK. 11ArtiJicial Radioactivity produced by a-Particles in Elements up toslBr,-The cyclotron may be used to accelerate He++ ions and togive a strong beam of energetic or-particles; 11 M.E.V. a-particleshave been obt'ained from the Berkeley cyclotron, and this may becompared with the natural a-particles of thorium-C' which havenearly 9 M.E.V. energy. A number of elements undergo transmut-ation in such a beam, and radioactive elements are sometimesformed by (a ; p ) and sometimes by ( a ; n) reactions. The case ofvanadium is interesting and not fully explained.30 It is possiblethat 64Mn exists in two isomeric forms. The formation of 78Brwas specially checked by A. H. Snel13' in his investigation of thebromine isotopes.TABLE I.Radioactive elements produced by a-particle bombardment (adaptedfrom Ridenour and Henderson 31).Type of activityReaction.and half-life. Other known reactions.l0B(a; rt)13N + 10.3 m. radioactive a's14N(a; n)17F + 1-07 m. radioactive a's 160(d; n)l60(p; y )Z6Mg(a; p)28A1 - 2.56 m. radioactive a's 27Al(d; ~)~7Al(n; y)27Al(a; n)3OP + 2-55 m. radioactive a's 32S(d; ~ ) ~ l P ( y ; n )31P(a; n)34Cl + 32 m. radioactive a's B3S(d; n)W l ( a ; n)38K 4- 7-65 m.41K(a; n)%c + 52 h.32, 34 4Wa(d ; n)40Ca(a ; p)43Sc + 4.0 h.33. 34 43Ca(d; n)4%47Ti(a; p)49. 60V ? 35 m.; 3.7 h.35 Ti(d; n)S0Cr(a; n)63Fe ? +Wr(a; p)66Mn - 160 m.63Cu(a; n)esGa + 9.4 h.3'3WU(U; h)G8Ga + 68 m.36 69Ga(n; Zn), ( y ; n)75Aa(a; n)78Br + 6.3 m.37 'OBr(.n; Zn), ( y ; n)V(a; ?)64Mn ? 1.2 m.; 67 m.8-9 m.66Mn(n; y )Br(a; n)Rb + 1.5m.Br(a; n)Rb + 9.8m.NUCLEAR DISINTEGRATION BY PROTONS.The Production of y-Rays by bombarding the Lighter Elements.-R.G . Herb, D. W. Kerst, and J. L. McKibben38 have examineda number of elements for y-ray emission on proton bombardment.y-Rays were found from Li, Be, B, F, Na, Al, but no certain emissionwas found from C, 0, Si, K, Ca, Ni, Cu, Zn, Mo, Pt, Pb. The emissionfrom lithium is known to be due to 7Li; 39 it consists of a strong line31 L. N. Ridenour and W. J. Henderson, PhysicaE Rev., 1937, [ii], 52, 889.32 D. G. Hurst and H. Walke, ibid., 51, 1033.33 H. Walke, ibid., p. 439.35 Idem, ibid., p. 777.37 Ibid., p. 1007.30 L. H. Rumbaugh and L. R. Hafstad, ibid., 1936, 50, 681.34 Idem, ibid., 52, 400.36 W.B. Mann, ibid., p. 405.38 Ibid., 51, 69112 RADIOACTIVITY AND SUB -ATOMIC PHENOMENA.a t 17 M.E.V.40 and one or more weaker lines around 14 M.E.V.E. R. Gaerttner and H. R. Crane 41 find indications of lower energycomponents, The first reaction is presumably the formation of a8Be nucleus, The y-rays may come from transitions within thisnucleus, or from the excited levels in the a-particles produced bythe disintegration of SBe. The former process seems the morelikely, and it fits in with processes suggested for the y-rays fromberyllium and boron bombarded by protons. The excited 8Behas to have a lifetime for a-particle disintegration long comparedwith its radiation life, and according to G .Breit42 the proton iscaptured to form an excited sBe which is supposed to be odd toexclude disintegration into two g-particles. The excitation functionof this disintegration shows a very sharp resonance maximum at440 kv., a broad maximum at about 1000 kv., and a smooth rise from1200 kv. upwards.The bombardment of beryllium gives y-rays up to about 6 M.E.V.,and the excitation shows a broad resonance a t about 990 kv. Thenuclear reaction is probably :Be@; -)':B, but the y-rays of lowerenergy might be emitted from excited product nuclei in :Be@ ; a)gLior :Be@; d)8,Be. Boron gave a y-radiation increasing smoothlywith bombarding voltage, but W. Gentner 43 finds a resonance at180 kv. and a further increase a t 360 kv. This may be comparedwith the excitation functions of the reactions 44(1)(2)l;B + iH --+ 3iHeIiB + iH ---+ !Be + :HeThe excitation of the reaction (2), as measured by the emission ofhomogeneous group of a-particles, also shows a resonance at 180 kv.It is therefore likely that the y-rays come from excited levelsof 8Be.The y-radiation from boron was formerly 45 attributed tothe excited levels of I2C formed by proton capture. It does not seemthat the process is excluded, particularly at high bombardingenergies.Fluorine gave a very large y-ray yield, and the excitation function40 L. A. Delsasso, W. A. Fowler, and C. C. Lauritsen, Physical Rev., 1937,4 1 Ibid., p. 49.42 See L. R. Hafstad, N. P. Heydenburg, and M. A. Tuve, ibid., 1936, 50,43 Naturwiss., 1937, 25, 12; W.Bothe and W. Gentner, 2. Physik, 1937,44 J. H. Williams, W. H. Wells, J. T. Tate, and E. L. Hill, Physical Rev.,46 H. R. Crane, L. A. Delsasso, W, A. Fowler, and C. C. Lauritsen, ibid.,[ii], 51, 391; 52, 582.504.104, 685.1937, [ii], 51, 434.1935, [ii], 48, 102BRADDICK. 13shows prominent resonances at 328,892,942,1400 kv., with a broadresonance at 600-700 kv. and indications of resonance at 1700 kv.46The y-radiation is largely monochromatic at about 6 M.E.V.E. R. Gaerttner and H. R. Crane 47 have obtained positron and elec-tron pairs produced by internal conversion of the y-rays in thetarget, and found a second y-ray line at 4 M.E.V. The nuclei W e ,formed by proton capture, and l60, formed by ( p ; a) change,have both been suggested as providing excited levels for the tran-sition. Sodium gave y-rays with a resonance at about 1200 kv.,but the energy of the y-rays has not been measured.The reactionmay be radiative capture, ;;Na(p ; - )2,iMg ; or ;:Na(p ; a)"Ne, with20Ne in an excited state. Aluminium gave a prominent resonanceat 1370 kv. and some weaker resonances.The theoretical significance of the resonances has been discussedby F. Kalckar, J. R. Oppenheimer, and R. Serber.4* In the re-actions considered the primary effect of the hydrogen particle issupposed to be the formation of a compound nucleus.7Li -/- 'H 4 8BeA + Z4He . . . . . . . . (1419F + lH-+ 20Ne,-+ l60 +4He . . . . . ' ( 2 4'Li + IH--+ 8BeB-> 8Be + y+ Z4He . . . . ( l b )19F + 1H 4 20Nes -+ l60, + 4He + l 6 0 + 4He + y (271)l9F + lH -+ 20Ne, -> 20Ne, + y --+ l60 + 4He + y (2c)IIB + lH~----+ 12C, -+ %eA + 4He I_, 34He .. . ( 3 4llB + lH -+ 12CB -> SBe + 4He (3b)llB + lH --+ 12CB --+ I2C + y ( 3 4The sharpness of the resonance in (lb), (2b or c), (3b or c) indicatesa relatively long lifetime for the excited compound nuclei denotedby subscript B. A satisfactory reason for this has been mentionedabove in the case of 8Be. An argument based on the idea that thetotal spin and orbital angular momentum of the neutrons andprotons can only change slowly with time explains the long life ofthe other nuclei against a-emission. A detailed discussion indicatesthat the y-rays obtained by bombarding fluorine come from l60(Zc, above).Proton-induced Radioactivity in Heavier Nuclei.-The elementsSi, Cu, Cr, Mn, Co, Ni, Zn, As, Se, Mo, Cd, In, Sn, and Sb showradioactivity after bombardment with 3.6 M.E.V.protons.49Data of the activities have not yet been published, but in the case46 L. A. Delsasso, W. A. Fowler, and C. C. Lauritsen, Phyeical Rev., 1937,[iiJ, 51, 527.4 7 Ibid., 52, 582.49 S. W. Barnes, L. A. I)u Bridge, E. 0. Wiig, J. H. Buck, and C. V. Strain,4 8 Ibicl., p. 279.ibid., 1937, [ii], 51, 77514 RADIOACTIVITY AND SUB-ATOMIC PHENOMEBA.of manganese it is supposed that a deuteron is emitted and a radio-active isotope of the metal formed.NUCLEBR DISINTEGRATION BY DEUTERONS.The bombardment of deuterium,50* 51 lithium, beryllium, or car-bon 51 with deuterons provides convenient sources of neutrons andhas been studied from this technical point of view (cf.p. 17). Thecase of deuterium has been investigated theoretically ; 52 thetransmutation function and the angular distribution of the pro-ducts can be calculated by application of quantum mechanics tothe nuclear components. The p-activity of SLi, resulting from7Li(&; p ) [an identical substance is obtained from Li(n; isnow found to be accompanied by an a-activity.a The a-particleshave also been detected by W. A. Fowler and C. C. Laurit~en,~5and by L. H. Rumbaugh, R. B. Roberts, and L. R. H a f ~ t a d . ~ ~Nuclear mass data had shown that there was an excess of energyof about 3 M.E.V. over that observed in the particles from the tworeactions7Li(d ; p)sLi, sLi+ sBe + pand no y-rays from excited sBe could be detected. It now seemsprobable that the 8Li always disintegrates into two a-particles and a@-particle, No a-particles could be detected from the bombard-ment of with deuterons or of 7Li with protons, though thesemight be expected if the a-particles were due to excited *Be.Aselection rule must be invoked to forbid the transition of 8Li tounexcited sBe. The a-particles form a continuous distribution,but the energy balance apparently requires the assumption of aneutrino as in ordinary p-decay (see p. 23).The transmutation functions for the reactions W ( d ; m)13N,14N(d ; n)15O, 160(d ; n)17F have been studied.57 They show thatthe potential barriers for deuterons are at 2.8, 3.2, 3.1 M.E.V.incarbon, nitrogen, and oxygen, respectively. For energies abovethese, the transmutation curves are complicated, probably owingto side reactions. The reactions 30Si(d; ~ ) ~ l S i , 3lP(d; p)32P havebeen found to occur.58 The products are previously known @-emitters of life 170 mins., 14.5 days. The very long-lived 22Na50 W. H. Zinn and S. Seely, Physical Rev., 1937, [ii], 52,919; R. B. Roberts,ibid., 51, 810; H. Kellmann and E. Kuhn, Naturwiss., 1937,25,231; R. Dopel,Ann. Physik, 1937, [v], 28, 87.6 1 E. Amaldi, L. R. Hafstad, andM. A. Tuve, PhysicaZReu., 1937, [ii], 51,896.62 L. I. Schiff, ibid., p. 783; M. H. Johnson, aid., p. 779.58 K. S. Knol and J. Veldkamp, Physica, 1937, 4, 166,64 W. B. Lewis, W. E. Burcham, and W.Y. Chang, Nature, 1937, 139, 24.66 PhysicaE Rev., 1937, CiiJ, 51, 1103.67 H. W. Newson, ibid., p. 620.66 Ibid., p. 1106.Idem, iM., p. 624BRADDICK. 15(positron emitter, 3.0 years) was produced by bombarding mag-nesium with 5-2 M.E.V. deuterons.59 The reaction seems to be!tMg(d ; a)gNa.The reactionsinvolved are probably uCa(d; p)"Ca, g29 93Ca(d; n)41* 439 44Sc,Wa(d ; CC)~~K.The products were separated chemically, and compared withthose of a- and neutron bombardment. The half-lives and types ofemission ascribed to the various isotopes are 45Ca (2-4 h., - ve),4% (53 m., + ve), 43Sc (4.0 h., + ve), (52 h., +ve). No evid-ence for 41Ca from 40Ca ( d ; p ) was obtained, though this reactionwould be expected. This substance may have a very long or a veryshort life.The bombardment of scandium 61 gives 46Sc by a( d ; p ) process. Titanium gives 51Ti witha half-life of 2.8 mins. and a number of isotopes of vanadiumformed by ( d ; n) reactions. These have been compared with otherproducts and assigned as follows : 4*V, 16 days; 49V, 33 mins.;V, 3.7 hrs. Strontium gives active isotopes of strontium andyttrium. There is some evidence that S9Sr has isomeric forms withhalf-lives of 3 hrs. and 55 days, both emitting electrom. It isalso possible that one of the processes observed with strontium isthe capture of a deuteron to formThe bombardment of indium gives periods of 13 secs., 54 mins.,and a few hours ; that of cadmium gives periods of 4.3 hrs., 58 hrs.,and a successive transformation of the latter gives a radioactiveiaotope of indium.The relations of these elements are indicatedin Table II.62At. no. 110 111 112 113 114 115 116 117The activity produced in calcium is complex.60The half-life is 85 days.TABLE 11.'&d 15% 15% 22% 15% 24% 4.3h.J. 16% 58h.$* Percentages are those of stable isotopes, and periods those of radioactiveisotopes ; changes denoted by 4 are #bray changes, and by .f positron changes.Addition of a neutron corresponds to a step 3, and of a proton to a step >.on bombarding palladium with J. D. Kraus and J. M.deuterons, obtained the following radioactive periods :Pd isotopes, 17 mins. (-), 13 hrs. (-)Ag isotopes, 26 mins. (+), 180 hrs. (-)6D L. J. Laslett, PhysicaZ Reu., 1937, [ii], 52, 529.6o H.J. Walke, ibid., 51, 439.62 L. J. Lawson and J. M. Cork, ibid., p. 531 ; J. M. Cork and R. L. Thorn-ton, ibid., 51, 608.e3 Ibid., 52, 763.61 Idem, ibid., 52, 669, 77716 RADIOACTIVITY AND SUB -ATOMIC PHENOMENA.In order to identify these activities they were compared withthose produced by irradiating silver and palladium with fast andwith slow neutrons.64 The results are indicated in Table 111.TABLE 111.At.no. ... 105 106 107 108 109 110 111asPd ...... 23% 27% 2704 13h.J 13.5% 17m.Ja7Ag ...... 180h. ~ 52% 2.3m.$48% 22s.$ 180h.4It may be noted that there are two different long periods in silver,one being produced in a chain reaction. The isotope 106Ag has bothp- and positron-emitting isomers. The reactions in deuteronbombardment include both ( d ; p ) and ( d ; n) types.NUCLEAR DISINTEGRATION BY NEUTRONS.E.Amaldi 65 has given a collective account of the production ofartificial radioactivity by neutron bombardment , which includesa table of the activities obtained up to the middle of 1937. Fewnew cases of the addition of slow neutrons have been found. Thenoble metals 66 have been investigated. Gold gives only the well-known 2.7-day activity; iridium gives, in addition to the 19-hr.and 2-month periods, a l.5-min. period, and platinum gives periodsof 31 mins., 18 hrs., and 3.3 days. Results were also obtained withfast neutrons (see p. 19). It appears that it is necessary to postu-late isomeric nuclei to explain the results.When uranium is bombarded with neutrons, a complicated setof reactions appear^.^' The primary products disintegrate, givingwhole families of radioactive elements, which lie beyond uraniumin atomic number.These have been further investigated by bom-barding uranium with neutrons for different times, so as to bringinto prominence the series beginning with elements of longer orshorter radioactive life. Some of the radio-elements were separatedchemically.26 m.4The families are now found to beB B 9,Eka-Ir %Eka-Pt Eka-Au( 1 )B B B (2) U(n; -)g,U 40s( Eka-Re Eka-0s Eka-IrB (3) U(n; -)92U Eka-Re( '1)64 Cf. p. 19.66 E. McMillan, M. Kamen, and S . Ruben, PhysicaE Rev., 1937, 52, 375.67 L. Meitner, 0. Hahn, and F. Strassmann, 2. Physilc, 1937, 106, 268;6 5 Physikal. Z., 1937, 38, 692.see Ber., 1937, 70, 1374 for chemical aspectsBRADDICK.17The existence of a (n; a) primary reaction 6* has now been dis-proved, though there is evidence of a weak a-emission of long lifesomewhere in the series. The f3-rays of the trans-uranic elementshave been examined in the Wilson chamber, and a y-radiation hasalso been detected.69 The reactions (1) and (2) occur with fast andwith slow neutrons, and the conditions for transmutation, togetherwith the yield obtained, suggest that the process involved is theaddition of a neutron to the abundant isotope ";U. The reaction(3) goes only with slow neutrons and is a very marked case of reson-ance. In this case the reaction can only be a simple addition of aneutron, and the cross-section for capture of slow neutrons shows thatthe abundant isotope is again involved.The phenomena thereforerequire three isomeric ';gU nuclei, and it is not clear how these areto be explained on von Weizsacker's theory of metastable states.70There is some evidence that if the theory applies to these elements,the nuclei of scheme (1) are in metastable excited states.F. A. Heyn 7 1 observed a neutron-induced disintegration of a newtype on bombarding certain elements with neutrons of high energy,obtained by bombarding lithium, beryllium, and hydrogen withdeuterons. The maximum energies of the neutrons me 12, 4.5,and 2.6 M.E.V. respectively. New radio-elements were producedfrom copper and zinc and shown to be isotopic with the originalelements. The character of the copper activity makes it probablethat the reaction isi.e., the removal of a neutron by neutron impact.In the case ofzinc the period the activity is 60 mins., like that produced by slowneutrons. The processes are supposed to beandtXZn(n ; 2n);:Zn (fast neutrons)ttZn(n ; -)$!Zn (slow neutrons)Subsequent work72~73 has shown that this type of activation isvery common, and a number of cases are given in Table IV. Thisincludes also (n; a) and ( n ; p ) reactions now observed with quiteheavy elements on account of the high energy of the lithium neutrons.In the case of scandium,74 the two periods of 4 hrs. and 2 days areidentified with 43Sc and 44Sc, in agreement with the results of68 L. Meitner and 0. Hahn, Naturwiss., 1936, 24, 158; Ann.Reports, 1936,83, 26.6s L. Meitner, Ann. Physik, 1937, [v], 29, 246.70 This vol., p. 21.72 F. A. Heyn, Nature, 1937, 138, 842.73 M. L. Pool, J. M. Cork, and R. L. Thornton, Physical Rev., 1937, [ii],74 Idem, ibid., p. 41.71 Physica, 1937, 4, 160.52, 239.76 Ibid., 51, 43918 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.Element.CN0F 3SiPSc1KC&scTiVCrMn3% coNicuZnGaGeAsSeBrR bSrYTABLE IV.*Activity and assignment. Other ramtiom.20 m.10.5 m.2.1 m.108 m.15 h.10 m.15 h.6 m.11 m.3 m.2.5 h.26 m.14 d.33 m.14 d.7.5 m.4 m.1.8 h.4.5 m.4 h.2 d.1.7 h.28 h.4 m.1.8 d.4 m.1.7 1.1.3.6 m.2.5 h.2.5 h.2.5 h.2 h.6 d.10 m.12.5 d.6 m.40 m.12.5 h.20 m.55 m.1.7 h.22 h.1-3 h.20 h.1.1 d.13 d.1 h.7 m.18 m.4 h.11 m.22 h.18 m.3 h.11 m.1.2 h.6.5 h.2.4 d.+I l'C$ 9 lSN +, l 5 0 +, 18F -, 24Na-, 12Mg-, 24Na +, 27Si +, +, -, Wi +, 31s -, 32P +, a4ci -, 3ZP +, SBK+, 39Ca +, 43scf, 44Sc9 sc3 sc-, 52v-, 52v-Y v-, s6Mn-, 5 w - n -, 56Mn-9 -, "A---, 62Cuj-, 64Cu 6 -, 66Cu +, Znf, 64Cu - , 70Ga +, 88Ga$ 9 -, 72Ga-, 72Ge-, 76A~Y se78Br80Br80Br- Y-- 9 -TI Sr-9-9 -, 90YP(y; n)3 m.82Cu(y; n)10.5 mea2Zn(y; n)38 m.82Ga(y; n)20 m.82Ga(y; n)60 m.82Ga(y; n)23 h.82Br(y; m ) 5 m.82Br(y; %)16 m.82Br(y; n)4.5 h.82* From Pool, Cork, and Thornton, ref.73Element.ZrNbMoRuRhPdAgCdInSnSbTeIB&Lac ePrNdGdDYTuReIrPtAuH gT1PbThUBRADDICK.TABLE IV,-Continued.Activity and msignment.Other reactions.10 m.5 h.44 h.7-3 m.3.8 d.17 m.5 d.24 m.3.6 h.4 m.1-1 h.18 m.12.5 h.25.5 m.13 d.33 m.3 h.53 h.1.1 m.54 m.4 h.2 mo.47 m.15.4 m.2.3 d.1.1 h.30 d.26 m.2.5 m.85 m.2.2 h.40 m.3 m.20 h.2.2 h.19 h.19 h.2.5 h.9.1 h.18 h.15 h.1.8 h.3 d.17 m.2.5 d.45 m.5 m.50 m.5 m.1.5 h.5 m.1.4 h.26 m.4 h. -,13 h. - , Eka-0sMo(y; n)17 m.82A g ( y ; n)24 m.82In(y; n ) l . l m.82Sb(y; n)15 m.8819who produced the same isotopes by bombarding calcium withdeuterons and potassium with or-particles.The case of bromine is specially interesting, since three radioactiv20 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.periods are produced whereas bromine has only two stable isotopes.Since it is most unlikely that the y-ray can remove two neutronsfrom the nucleus, this effect is believed to be a case of nuclearisomerism, and SOB, to exist in two forms with different radioactivepr0perties.~6 The nuclear cross-section for this process was estim-ated for the case of copper as 5 x and in the case of theother elements the probability of disintegration was of the sameorder of magnitude.Many elements, however, show an unobservable small effect,so it is probable that a resonance process occurs.The effect is afew hundred times greater than predicted by H.A. Bethe and G .Placzek 77 on their assumption of nuclear resonance levels spacedso closely that selective resonance does not occur.The production of 43Sc by neutron bombardment involves theejection of three neutrons (including the bombarding particle).This is not inconsistent with the Bohr view of an excited intermediatenucleus. It is possible that the reactions 19F(n ; 3n)17F(17FY 1.2 mins.)and 63Cu(n; 3n)61Cu(61Cu, 3.5 hrs.) occur in this way, but theidentification of these activities is not certain.THE NUCLEAR PHOTO-EFFECT.The extraction of neutrons from a nucleus by y-rays ( y ; ntransition or nuclear photo-effect) 78 has hitherto been known onlyfor 2H(y; n)lH and sBe(y; n)8Be. F. A. Paneth and E. Gliickaufhave detected helium by microchemical methods and decided that4He is the main product of the beryllium reaction.79 The nuclearcross-section for the effect in beryllium has been obtained for twovalues of the 7-frequency, and there is satisfactory agreement withcalculation based on the method of Bethe and Peier1s.mThe nuclear photo-effect depends simply on the energy of the y-raybeing sufficient to extract a particle from the nucleus. The reverseprocess (capture of a neutron with emission of a y-ray) *l is known, andthe energies have been estimated.A great extension of the nuclearphoto-effect has been made 82 by the use of the very energeticy-rays (about 17 M.E.V.) obtained by bombarding lithium with' 6 Cf. this vol., p. 21 and refs. 37, 82.7 7 Physical Rev., 1937, [GI, 51, 450.78 Ann.Reports, 1935, 32, 28; 1936, 33, 26.7Q Nature, 1937, 139, 712.L. I. Rusinov and A. N. Sagaidak, Physikal. 2. Sovietunwn, 1936, 10,203; V. I. Mamaschlisow, ibid., p. 214; H. A. Bethe and R. Peierls, Proc.Roy. Xoc., 1935, A , 148, 146.81 R. Fleischmann, Naturwiss., 1936, 24, 77; 2. Physik, 1936, 103, 113;S. Kikuchi, K. Husini, and H. Aoki, Nature, 1936, 137, 992.82 W. Bothe and W. Gentner, 2. Physik, 1937, 106, 236; preliminaryannouncements in Naturwiss., 1937, 25, 90, 126, 191, 284BRADDICK. 21protons.83 A large number of elements were examined, and thepositive results obtained are indicated in Table V. The productsof the photodisintegration were radioactive elements which wereidentified chemically as isotopes of the original elements.In somecases they could be shown by their radioactjive properties to beidentical with the products of previously known nuclear reactions.There is an obvious and close connection between the photoelectricextraction of a neutron from the nucleus and the removal of a neutronby impact in the ( n ; 2n) reactions described on p. 20. There isin most cases a satisfactory identity between the properties of theradioelements obtained in the two ways.TABLE IT.P, Cu, Zn, Ga, Br, Mo, Ag, In, Sb as indicated in Table IV. In addition :Br(y; n)36 h. Ag(y; n)22 s. Te(y; n)60 m.NUCLEAR ISOMERISM.Recent studies of nuclear transmutation in indium,62 rhodium,bromine, uranium,67 silver,63 and iridium and platinum 66 have ledto the conclusion that there exist nuclei identical in charge andmass but differing in radioactive properties.I n the naturalradioactive series, UX, and UZ, have long been believed to be anisomeric pair with 2 = 91 and A = 234.84 C. F. von Weizsacker 85has suggested that the difference between these isomers is due todifferent states of excitation. The y-ray transition between anexcited state of a nucleus may be " forbidden " by selection rulesif it involves a spin change, and the probability of transition isreduced for greater spin changes. It appears that for reasonablevalues of the spin change the probability may be so low that themetastable excited nucleus has a sufficiently long life to accountfor nuclear isomerism.Furthermore, the paray transition is governed by selection rules,so the product nucleus from a P-disintegration of a meta-stablenucleus may itself be in a metastable excited state.This accountsfor the production of parallel families of isomers as in the case ofuranium.I n the cases of 54Mn and Ag 63 it is believed that one nuclearisomer emits positrons, and the other electrons.It has been shown 86 that the production of y-rays by fast neutrons83 L. A. Delsasso, W. A. Fowler, and C. C. Lauritsen, Physical Rev., 1937,[ii], 51, 391, and references therein; this vol., p. 11.84 0. Hahn, 8. physikal. Chem., 1922, 103, 461.85 Naturwiss., 1936, 24, 813.86 G. T. Seaborg, G. E. Gibson, and D. C. Grahame, Physical Rev., 1937,[ii], 52, 40822 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.in a number of elements is due to inelastic collisions in which theneutron raises the nucleus to an excited state and goes on withdiminished energy.THE INTERACTION BETWEEN NEUTRON AND PROTON.It is now generally assumed that neutrons and protons are thefundamental constituents of all nuclei and it is important to obtaindata on the forces between them.The stable existence of thedeuteron shows that this force is attractive and the binding energyof the deuteron has been determined as 2.25 M.E.V.87 The inter-action of neutrons and protons may be studied by investigating thescattered particles when neutrons pass through hydrogen gas in acloud chamber.Former experimental data have been rather conflicting, but therecoil proton tracks produced by the homogeneous 2-6 M.E.V.neutrons from the D(d.3He) reaction have now been investigated byseveral groups of workers.88 The distribution of recoil particles seemsto be nearly spherically symmetrical with respect to the centre ofmass of the moving particles.The theory of these collisions hasbeen worked out 89 under a variety of assumptions. It appearsthat the observed isotropic distribution shows that the interactionbetween neutron and proton is very small a t separations greater than3 x 10-13 cm., and is not consistent with '' exchange forces " betweenthe particles. It is not, however, yet possible to obtain any preciseconclusions about the shape of the potential well. In these calcula-tions it is assumed that the range of the interaction does not dependon the spins of the particles.The binding energy of the deuteron isdue to the interaction energy of the particles with parallel spins,while the large scattering of slow neutrons by hydrogen indicates,according to Wigner,go a weaker interaction with antiparallel spins.J. Schwinger and E. Tellerg1 have shown that if the interactiondepends on the spin of the particles, the scattering of very slowneutrons by ortho-hydrogen (molecule with parallel proton spins)should be much greater than for para-hydrogen (antiparallel spins)87 J. Chadwick, N. Feather, and E. Bretscher, Proc. Roy. SOC., 1937, A ,183, 366.P. I. Dee and C. W. Gilbert, ibid., p. 265; P. G. Kruger, W. E. Shoupp,and F. W. Stallmann, Physkd Rev., 1937, [ii], 52, 678; T.W. Bonner, ibid.,p. 685; G. W. Lampson, D. W. Mueller, and H. A. Barton, ibid., 51, 1021.*O H. S. W. Massey and R. A. Buckingham, Proc. Roy. Soc., 1937, A , 163,281; H. A. Bethe and R. F. Bacher, Rev. Mod. Physics, 1936, 8, 82; P. M.Morse, 3. B. Fisk, and L. I. SchifT, Physical Rev., 1937, 51, 706; S. Shareand J. R. Stehn, ibid., 52, 48.O0 See Bethe and Bacher, ref. 89.s1 Physical Rev., 1937, [ii], 52, 286BRADDICK . 23on account of an inelastic scattering process which appears in theformer case. This effect has been found by e~periment.~2 Thescattering of neutrons by deuterons has been calculated, in fairagreement with experiment .93THE MAGNETIC MOMENT OF THE NEUTRON.It has been found possible to produce partly polarised neutronbeams (Le., beams which contain more neutrons of one direction ofspin than the other) by passing a beam of slow neutrons through aplate of magnetised iron.94 This effect is due to the interaction ofthe magnetic moment of the neutron with that of the ferromagneticatoms.0. R. Frisch, H. von Halban, and J. Kochg5 showedthat a neutron beam polarised in this way should be depolarisedby passing through an axial magnetic field on account of theprecession of the magnetic neutrons, and they found that the mag-netic moment of the neutron was probably 2 nuclear magnetons.The sign of the magnetic moment was shown to be negative,96 andprobably -2 nuclear magnetons as expected from the proton anddeuteron moments. An attempt has been made to detect themagnetic scattering of slow neutrons, by comparing the scatteringof a mixture of manganese and sulphur with that of the sulphidecontaining the manganous ion.No positive results have beenobtained .9THE RAY DISINTEGRATION.The present position of the @-disintegration has formed the sub-ject of a Royal Society discu~sion.~~ The main difficulty remainsthat the @-particles form a continuous energy distribution and thatthis fact cannot be directly reconciled with the conservation ofenergy and the identity of all the atoms of the initial and finalsubstances. A suggestion that the nuclear P-rays might differin mass from other electrons has been tested, with negative results,by C. T. Zahn and A. H. S p e e ~ . ~ ~ The Fermi theory and its deriv-92 J.Halpern, I. Estermann, 0. C. Simpson, and 0. Stern, Physical Rev.,1937, [ii], 52, 142; J. R. Dunning, J. H. Manley, H. J. Hoye, and F. G.Brickwedde, ibid., p. 1076.09 L. I. SchB, ibid., p. 149.94 F. Bloch, ibid., 1936, [ii], 50, 259; J. G. Hoffmann, M. S. Livingston,and H. A. Bethe, ibid., 1937, 51, 214; J. R. Dunning, P. N. Powers, andH. G. Beyer, ibid., 51, 51, 371, 1112.95 Nature, 1937, 139, 756, 1021.0 8 P. N. Powers, J. R. Dunning, H. Carroll, and H. Beyer, Physical Rev.,9 7 M. D. Whitaker, ibid., p. 384; 0. Halpern and M. H. Johnson, ibid.,0 8 C. D. Ellis et al., PTOC. Roy. SOC., 1937, A , 161, 447.09 Physical Rev., 1937, [ii], 52, 524.1937, 52, 38.p. 5224 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.atives 1 postulate that the nucleus contains neutrons and protonswhich are to be considered as states of the same particle.Where itis energetically possible, one of these states may switch over to theother with emission of a P-particle (n + p ) or a positive electron( p --+ n). The energy of the disintegration is represented by themost energetic p-ray emitted, and the simultaneous emission of aparticle called the neutrino is required to explain the continuousenergy distribution. The modifications of this theory depend ondifferent assumptions about the law of interaction between nuclearparticles. The theories give results, which can be compared withexperiment, for the form of the p-ray energy distribution curve andfor the relation between the disintegration constant of t,he nucleiand the energy of the P-particles. The conclusion that the upperlimit of the p-spectrum corresponds with the disintegration energyhas been very well confirmed by measurements of the p-spectrumin light radioactive elements.2 In the case of carbon bombardedwith deuterons the reactions12C 4- 2H -+ I3C + lH + Q1 or 13N + n + Q213N -+ 13c + p+ + &3 + vwhere Q1 and QZ are energies carried off respectively by the protonsand neutrons in the two reactions, Q3 is the energy of the @-trans-formation, and v is the neutrino mass.Mass-spectrograph resultsexclude the possibility of energy loss by y-radiation. Q3 (+ energyequivalent to v) = 1.08 f 0.1 M.E.V., whereas the estimated end-point of the p-spectrum is a t 1-25 & 0.1 M.E.V.Similar resultswere obtained by the reactions I O B ( d ; n or p ) , 160(d; n or p ) , and27Al( cc ; n or p ) . The results show also that the neutrino mass mustbe small and the limits of error place it as less than one-fifth of theelectron mass.The general form of the energy distribution of the p-particlesfrom radium-E3i4 and 32P395 fits over a large part of the rangewith the theory of Konopinski and Uhlenbeck. The high end-point of the spectrum does not agree with the theory, for this pre-dicts an asymptotic tail which is definitely excluded by theexperiments of Lyman and of Paxton. Similarly, work on thep-spectra of 8Li and 12B shows that the end-point obtained by1 E. Fermi, 2. Physik, 1934, 88, 161 ; E. J. Konopinski and G. E. Uhlen-2 J.D. Cockcroft, Royal Society Discussion, Zoc. cit., ref. 98.3 C. M. Lyman, Physical Rev., 1937, [ii], 51, 1.4 L. M. Langer and M. D. Whitaker, ibid., p. 713; J. S. O’Conor, ibid.,beck, Physical Rev., 1935, [ii], 48, 7, 107.52, 303.H. C. Paxton, ibid., 51, 171.6 D. S. Ragley and H. R. Crane, ibid., 52, 604BRADDICK. 25extrapolation according to Konopinski and Uhlenbeck is much toohigh. The lower-energy part of the thorium-C’ p-spectrum ha,sbeen investigated by using a radioactive vapour in an expansionchamber.’ This method avoids complications due to the absorptionand scattering of the low-energy particles in window or support.The energy distribution does not go to the origin, but shows a largenumber of particles of low energy.This is in accord with theKonopinski-Uhlenbeck formula, if the electrostatic effect of thenuclear charge on the escaping P-particle is taken into account.Similar conclusions follow from Paxton’s work on 32P and B. Z.Dzelopov’s on 28A1, 30P, 152E~, and Ra-E.8 H. 0. W. Richardsonfinds that the shape of the spectrum is given over a wide range by acombination of the Fermi and the Konopinski-Uhlenbeck form~lae.~It is not yet certain how far theory agrees with experiment in thecorrelation of p-ray energies and radioactive lives. A. C. G .Mitchell lo makes Sargent logarithmic plots of the disintegrationconstants against the end-points of the p-ray spectra of a numberof radio-elements as determined by Konopinski-Uhlenbeck extra-polation. He finds that each point lies on one of three lines (Sargentcurves).The lines are supposed to correspond with different spinchanges (“ allowed ” and “ forbidden ” transitions), and thereis a partly successful attempt to fit the spins of a number of nucleiinto a simple scheme.ll Richardson 9 shows that the Konopinski-Uhlenbeck expression for the relation between life and energyis not in agreement with experiment for the P-rays from Th-C”,Th-B, and Ra-D, which are all “ permitted ” transitions, and thatthe Fermi formula fits these cases better. On the other hand,the Konopinski-Uhlenbeck expression gives a correct representationof the relative periods of p-decays of high energy, with end-points 2-12 M . E . V . Richardson finds that a formula containingboth Fermi and Konopinski-Uhlenbeck terms gives a goodapproximation throughout the spectrum.THE PASSAGE OF ENERGETIC p- AND RAYS THROUGH MATTER.The important application of the quantum theory of the inter-action of hard p- and y-rays with matter to the cosmic-ray problemis described on p.26. Several investigations have been made onthe absorption of electrons of moderately high energies (1-11H. 0. W. Richardson and A. Leigh-Smith, Proc. Roy. SOC., 1937, A , 162,391.8 Bull. Acad. Sci. U.R.S.S., 1936, 673.9 Royal Society Discussion, loc. cit. ; Nature, 1937, 139, 505.10 Physical Rev., 1937, [ii], 52, 1.11 Cf. calculations of M. Rose and H. A. Bethe, ibid., 51, 20526 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.M.E.V.) in heavy gases l2 or thin laminae l3 in a cloud chamber.In the experiments with gases it was concluded that large, suddenenergy losses, due presumably to production of radiation, occurredmuch more often than was to be expected from the current theory.The energy loss found by Turin and Crane in a light element, carbon,was in good agreement with theory.Radiation is here small.In lead, they found an average energy loss rather greater thantheoretical, but the discrepancy was not much greater than could beaccounted for by the increased path in the lead due to scattering.Laslett and Hurst, on the other hand, found energy losses markedlygreater than theoretical, and a special investigation of large energylosses showed a frequency many times the theoretical. A recentrevision of the theory 14 does not much alter the theoretical result,so that further investigation will be needed.There is some evidencefor pair production by C3-1-ays.l~ In the case of energetic y-rays,pair production becomes a most important interaction with matter.The angular distribution of the pairs has been studied.16 It hasbeen shown 1 7 that the study in a cloud chamber of the pairs pro-duced by y-rays is a convenient and reliable method of investigatingthe spectrum of the latter.THE PENETRATING RADIATION.Considerable advances have been made in the study of the cosmicradiation as a result of the application of quantum-mechanicalcalculations, known to be more or less valid in the medium-energyrange, to electrons of high energy.l**l9 A fast electron will loseenergy in the form of radiation quanta (" Bremsstrahlung "), andthe quanta will in turn produce positron-electron pairs.A cosmic-ray shower will thus arise as a complicated cascade process, and allthe particles and photons will preserve the general direction of theprimary particle. Direct calculations on these assumptions givethe numbers of emergent particles when a single particle falls on12 H. Klarmann and W. Bothe, 2. Physilc, 1936, 101, 489; L. Leprhce-Ringuet, Ann. Physique, 1937, 7, 5 .1s 5. J. Turin and H. R. Crane, PhysiccsE Rev., 1937, [ii], 52, 63, 610; L. J.Laslett and D. G. Hurst, ibid., p. 1035.J. C. Jaeger, Nature, 1937, 140, 108.lS F. C. Champion and A. Barber, ibid., p. 105; M. MonadjBmi, Compt.rend., 1937, 204, 1560.l6 L.Simona and K. Zuber, Proc. Roy. SOC., 1937, A, 159, 383; H. Adam,Naturwiss., 1937, 25, 13.1 7 L. A. Delsasso, W. A. Fowler, and C. C. Lauritsen, Physical Rev., 1937,[ii], 51, 391. Cf. E. R. Gaerttner and H. R. Crane, ibid., 52, 582.la H. J. Bhabha and W. Heitler, PPOC. Roy. SOC., 1937, A, 159, 432; 5. F.Cerlson and J. R. Oppenheimer, PhysicaE Rev., 1937, [ii], 51, 220.W. Heitler, Proc. Roy. SOC., 1937, A , 161, 261BFtADDICK. 27absorbers of different thicknesses. They reveal the main featuresof the Rossi transition curve in which number of showers is plottedagainst thickness of shower-producing material.lQ~~ They arefurther supported by special transition-curve experiments,21 andby the appearance of obvious cascade processes in many cloud-chamber photographs of showers.Similar calculations may bemade to give the main features of the phenomena of the passageof comnic rays through the upper atmosphere.22I. S. Bowen, R. A. Millikan, and H. V. Neher 23 measured cosmic-ray intensities to great heights in the atmosphere a t two differentlatitudes, and the difference between these sets of measurementsis interpreted as the effect of electrons cut off by the earth's magneticfield at the lower latitude and having energies between 6700 and17,000 M.E.V. These electrons behave in fair accord with thequantum theory predictions. The theory apparently gives a satis-factory account of the behaviour of the soft part of the rays (ab-sorbed in 10 cm. of lead) and of the greater part of the showers.The penetrating particles, which form about 80% of the verticalintensity a t sea-level and can in some cases penetrate hundreds ofmetres of water, have no obvious place in the theory, and their natureis one of the outstanding cosmic-ray problems.Heitler l9 examinesas alternatives the possibilities that they are non-electronic particles,and that the theory breaks down for very high electron energies.It appears that a breakdown of the formule for energies below about10,000 M.E.V. would spoil the explanation of the curve in the upperatmosphere. According to P. M. S. Blackett and J. G. Wilson?very few electrons following the theory a t high energies are observedat sea-level. They measured the energies of a large number ofindividual particles before and after passage through a metd plate,and found that the energy loss of particles of energy below about250 M.E.V.was nearly that given by the quantum theory for elec-trons. The particles above this limit were in the main fax morepenetrating, though a few electrons were also found. The energyloss for the penetrating particles appears to pass through a mini-mum and then increase very slowly with increasing energy. Nopenetrating particles were found with energies lower than thecritical value, and it seems that penetrating particles must appearas electrons when they enter the lower-energy range. In anunpublished experiment 25 the behaviour of particles in a gold plate20 W. H. Furry, Physical Rev., 1937, [ii], 52, 569.21 P.Auger, P. Ehrenfest, A. Freon, and (Mlle.) T. Grivet, Compt. rend.,22 See Ann. Reports, 1930, 33, 33.24 proc. Roy. SOC., 1937, A , 160, 304.26 p. M. S. Blackett, ibid., in the press.1937, 204, 1797.Physical Rev., 1937, [ii], 52, 8028 RADIOACTIVITY AND SUB-ATOMIC PHENOMENA.was studied after preliminary passage through a thick lead filter.The particles after passage through the lead still showed divisioninto a penetrating and a non-penetrating group, with a demarcationat 200-250 M.E.V., and this experiment suggests that penetratingparticles may turn into non-penetrating particles. C. D. Andersonand S. Neddermeyer,26 working in the energyrange 100-500 M.E.V.,found penetrating andnon-penetrating particles throughout the range.Particles occurring singly were penetrating, and electronic particlesoccurred in showers or produced showers.Their experimentalresults are in conflict with those of Blackett and Wilson, whofind only electronic particles over the lower part of the energyrange, and this discrepancy may reasonably be explained by thelower accuracy of their energy determinations. Anderson andNeddermeyer suggest that the penetrating particles have an elec-tronic charge combined with a mass between those of the electronand the proton. Unfortunately, particles can only be distinguishedin mass by their specific ionisation when near the end of theirrange, and there is little evidence of this kind for the existence of aheavy electron. E. C. Stevenson and J. C. Street 27 used a cloudchamber arranged specially to catch particles near the end of theirrange, and observed one proton and one particle estimated to have130 times the electronic mass. These authors2* also showed,from consideration of the range of penetrating particles of measuredenergy, that many particles were neither Heitler electrons norprotons .The very penetrating part of the cosmic rays has been studiedunder 240 m. of water,29 and shower intensities proportional to thevertical intensities were obtained down to this depth. Showers andbursts have been detected under the equivalent of 800 m. of water.30Since Heitler electrons of reasonable energy cannot penetratemore than a few metres of water, these showers must be producedby electrons secondary to the hard radiation, or by an entirelydifferent process-perhaps that suggested by W. Hei~enberg.~~Unpublished work by L. J&nossy32 suggests that both these pro-cesses are operative.The existence of heavy particles, protons,33 and neutrons 3426 Physical Rev., 1937, [ii], 51, 885.27 Ibid., 52, 1003.20 A. Ehmert, 2. Physik, 1937, 106, 751.ao Y. Nishina and C. Ishii, Nature, 1936, 138, 721.31 2. Physik, 1936, 101, 533.32 Cf. P. Auger and G. Meyer, Compt. rend., 1937, 204, 572.3s C. D. Anderson and S. Neddermeyer, Physical Rev., 1936, [ii], 49, 415.34 E. Schopper, Naturwiss., 1937, 25, 557; B. Arakatsu, K. Kimura, and28 Ibid., 51, 1005.Y. Uemura, Nature, 1937, 140, 277BRAD DICK. 29has been reported in cosmic-ray experiments, and these are usuallyregarded as secondaries produced, e.g., by the nuclear photo-effect.A suggestion has been made 35 that the magnetic field of the sunacts to prevent cosmic electrons of low energy from reaching theearth. This explains the observation that the effect of latitudeon cosmic-ray intensity ceases above about 50" N., even at a con-siderable altitude.36 It is not yet certain if the sun's field is adequatefor this effect.H. Alfvbn 37 has suggested a mechanism for accelerating electronsto very high energies in a double star. The electric and magneticfields of the star behave like those in a cyclotron, and the electronsare accelerated by multiple stages. The energies calculated onreasonable assumptions about the field are of the right order ofmagnitude to account for cosmic rays.H. J. J. BRADDICK.85 L. Jhossy, 2. Physik, 1937, 104, 430; M. S. Vallarta, Nature, 1937,86 M. Cosyns, ibid., 1936, 137, 616.87 Ibid., 1936, 138, 761; Compt. rend., 1937, 204, 1180.139, 839

ISSN:0365-6217    

DOI:10.1039/AR9373400007

出版商:RSC    

年代:1937

数据来源: RSC

摘要:

GENERAL AND PHYSICAL CHEMISTRY.1. INTRODUCTION.THE chemistry of deuterium and its compounds continues to provea fruitful field of investigation, and since the last Report ondeuterium, published two years ago, nearly 300 papers have beenpublished dealing with various aspects of the subject. It is not aneasy matter to review all this work in one article, especially as manyof the studies have been made in connexion with spectroscopicinvestigations and with the object of elucidating the mechanisms ofthermal and photochemical reactions. The general and physicalchemistry of deuterium is, therefore, described in one section ofthe Report and references are given to other articles, in this andprevious Reports, where applications relating to particularproblems are mentioned.Attention should be called here to animportant symposium on “ Deuterium and its Compounds ” heldunder the auspices of the Bunsen Gesellschaft in September,1937 ; the papers contributed are important, not so much for thenew work reported, as for the fact that they are generally verycomplete surveys of the field with full references to the originalpapers. Mention may be made of the doubt which has been caston the existence in Nature of a third isotope of hydrogen, withmass number 3, called tritium. It will be of interest to see if theclaim2 to have obtained water enriched in this isotope can besubstantiated. As forecast in a previous Report, supplies of watercontaining appreciable proportions, vix., 2-3 yo, of H,180 are nowbecoming available both in England and in the U.S.A., andprogress in the study of isotopic exchange reactions with oxygenis to be expected.The most satisfactory method of preparing thiswater is by fractional distillation. Developments are aIsomentioned in this Report of the partial separation of the isotopesof lithium, carbon, nitrogen, and argon by physical and chemicalmethods.Once again a report on chemical kinetics is inevitable : variousaspects of the subject have been discussed at meetings of theChemical Society and the Faraday S~ciety.~ Although noimportant advance is to be recorded in the “ transition-state ” or‘‘ activated-complex ” theory of reaction velocity, the fundamental1 2. Elektrochem., January 1938.3 For references, see this vol., p.44.See Ann. Reports, 1935, 32, 50GLASSTONE : INTRODUCTION. 31assumptions of the theory have been examined, with the resultthat there has been a clarification of the essential postulates.Progress continues to be made in the study of the combustion ofgaseous hydrocarbons and of reactions in solution.It is five years since the subject of photochemistry was treatedin a comprehensive manner in these Reports: in the intervalthere have been many advances, both in the study of photochemicalprocesses and in the parallel field of light absorption. Particularmention may be made of progress in the investigation of thephotolysis of carbonyl compounds and of the hydrogen-chlorinereaction. Many of the complexities of the latter process have nowbeen straightened out, and it is probably not an exaggeration tosay that the problem is well on the way to a solution as completeas is compatible with the limitations of the present state ofscientific knowledge.One of the most striking developments of this decade is theattention paid to the study of intermolecular, i.e., van der Waals,forces and to the theory of the liquid state.The time isundoubtedly ripe for an account of the present status of these andrelated subjects. Owing to the diversity of interests involved inthe study of liquids, it has been necessary to leave some aspects tobe considered in the section of this Report dealing with Crystal-lography. During 1936 the Faraday Society held a discussion on“ Structure and Molecular Forces in Liquids,” and in 1937 thecentenary of the birth of van der Waals was celebrited by asymposium, held in Amsterdam, on the properties of liquids andhighly-compressed gases.The papers have been publi~hed,~ andthe whole forms a valuable contribution to our knowledge of theliquid state and of solubility. It is appropriate to record theappearance of a second edition of J. H. Hildebrand’s well-knownmonograph on solubility : the revision has been so thoroughthat it is virtually a completely new work.Although there have been no spectacular developments,interesting results have been obtained in various fields of theelectrochemistry of solutions : a few only of these have been chosenfor discussion in this Report. Special attention may be called tothe method for determining dissociation constants of acids whichappears to be, from the theoretical standpoint, the most reliableprocedure yet devised.In conclusion, attention may be directedto the publication of a new edition of it familiar text-book,g and of4 For references, see this vol., p. 75.5 “ Solubility of Non-Electrolytes,” Reinhold Publishing Corporation, New6 S. Glasstone, “ The Electrochemistry of Solutions,” Methuen and Co.,York, U.S.A., 1936.Ltd., 193732 GENERAL AND PHYSICAL CHEMISTRY.a, monograph in which an attempt is made to interpret theproperties of ions in solution in terms of energy levels.'The writer wishes to place on record his sincere appreciation ofthe work of those who have so generously collaborated with himin the compilation of the General and Physical Chemistry sectionof these Reports during the past three years.S. G.2. NON-RADIOACTIVE ISOTOPES.(Continued from Ann. Reports, 1935, 32, 40.)Deuterium.-Separation. The normal value of the separationfactor * in electrolysis is about 6-43, but in the previous Report 1mention was made of the possibility of an exceptionally highfactor, about 100, in water containing relatively little deuterium.This result, which was of great theoretical importance since itappeared to be a striking instance of " quantum-mechanicalleakage," was based on the value for the H/D ratio in normalwater concerning which there was some uncertainty, One of thechief causes of error in the latter connexion has been the failure tomake allowance for the change in the isotopic composition ofoxygen in the preparation of deuterium-free water as a standard ofcomparison; this has been done in recent work and the followingH/D ratios in ordinary water have been recorded : 6400 & 200(Lake Mendota, Wisconsin),2 > 5600 (Osaka, Japan),3 and 6900(Lake Michigan)? From new experimental work it appears thatif the last of these ratios is accepted the separation factor in theelectrolysis of dilute alkali has an average value of about 7 at anickel cathode, both in normal water (0-014% D,O) and in watercontaining 0.25y0 of D,O.If the normal water has a higherdeuterium content than that implied by the H/D ratio of 6900, theseparation factor would be even lower.It is suggested, therefore,that the abnormally high factor mentioned above is in error.5From time to time reports have been published of the presence ofa higher concentration than normal of deuterium in substances ofnatural origin6 It is probable that some of these results are in7 R. W. Gurney, " Ions in Solution," Cambridge Univ. Press, 1936.1 Ann,. Reports, 1935, 32, 41.2 N. F. Hall and T. 0. Jones, J . Amer. Chem. Xoc., 1936, 58, 1916.3 N. Morita and T. Titani, BulE. Chem. SOC. Japan, 1936, 11, 403.4 J. L. Gabbard and M. Dole, J. Amer. Chem. Xoc., 1937, 59, 181.5 H. F. Walton and J. H. Wolfenden, J., 1937, 1677.6 For summaries, see M. Dole, J. Amer. Chem. SOC., 1936, 58, 580; N.Morita and T. Titani, Bull. Chem. SOC. Japaw, 1936, 11, 419; see also J.S.Anderson, H. V. A. Briscoe et al., J., 1937, 1492.separation factor is the H/D ratio in the gas divided by the H/Dratio in the liquid phase.ULASSTONE : NON-RADIOACTIVE ISOTOPES. 33error because, when the substances are burnt, the oxygen in theresulting water has not the same isotopic composition as theoxygen in ordinary water (cf. p. 42) : the observed differences indensity may be due to this cause and not to differences in theisotopic ratio of the hydrogen. After making all the necessarycorrections, it has been found that the H/D ratio in benzeneJ8presumably originating from coal, in cholesterol, and in halibut-liveroil9 is approximately the same, within the limits of experimentalerror, as in normal water. In view of the possibility that watersfrom different sources may have different isotopic ratios of bothhydrogen and oxygen, it might be desirable to define the litre andthe Centigrade degree in terms of lH216Q; because of thedifliculty of obtaining this substance it is recommended that thepresent definition be maintained, but that the source and treatmentof the water should be specified.10 The problem of isotopiccomposition as related to the determination of atomic weights hasbeen already considered.l1The deuterium content of the occluded gas obtained from apalladium cathode after electrolysis is greater than that evolvedduring electrolysis : l2 this result is explained in terms of thetheory of Halpern and Gross,13 that the electrolytic separation ofhydrogen and deuterium is due to the different rates of combinationof the atoms on the surface of the electrode.The same view issaid to be supported by theoretical considerations based oncalculations of absolute reaction velocities by the transition-statemeth0d.1~ On the other hand, arguments have been put forwarc!in support of the suggestion that the electrolytic separation canbe explained by the different rates of discharge of hydrogen anddeuterium ions, resulting from the difference in the zero-pointenergies of the hydrated protons (H30+) and deuterons (D,O+).15It is of interest in this connexion that wnaphthaquinoline, whichmight be expected to inhibit any catalytic process in the separationof hydrogen and deuterium, actually lowers the Separation factorsat mercury and silver cathodes, and also reverses the sign of thetemperature coefficient .168 M.Dole, loc. cit.M. Dole and R. B. Gibney, J . Amr. Chem. SOC., 1936,58, 2552.10 E. H. Riesenfeld and T. L. Chang, Physilcal. Z., 1936, 37, 690.11 Ann. Reports, 1936, 33, 141-142.12 A. Farkas, Trans. Paraday Soc., 1937, 33, 552.13 Ann. Reporta, 1935, 32, 41.14 G. Okamoto, J. Horiuti, and K. Hirota, Xci. Papers Inst. Phys. Chem.16 J. A. V. Butler, 2. Elektrochem., 1938, 44, 55.16 H. F. Walton and J. H. Wolfenden, Nature, 1936, 138, 468.Res. Tokyo, 1936, 29, 223.REP.-VOL. X X W . 34 QENERAL AND PHYSICAL CHEMISTRY.In addition to work on the electrolytic method, research has beencontinued on other methods of separation of the isotopes ofhydrogen: the efficiency of the diffusion method, using Hertzpumps, has been co&med,17 and another procedure, in which arapidly moving stream of mercury vapour acts as the membrane,has been described.18 Preliminary experiments have shown thatfractional desorption of hydrogen and deuterium gases fromactivated charcoal in a vacuum is an efiicient method of separation,l9and the separation of light and heavy waters by distillation hasbeen considered further.20 The failure to bring about enrichmentof deuterium by crystallisation of salt hydrates has beenalthough there appears to be a difference of opinion as to whetherthe isotopic ratio in the first four molecules of water of crystal-lisation of copper sulphate is the same as in the fifth molecule.22Analysis.Improvements have been recorded in the methodsfor determining the isotopic composition of hydrogen and itscompounds. The procedure involving measurement of the densityof small quantities of water has received some attention,23 and anumber of workers have used the thermal-conductivity methodwhich is applicable to minute quantities of hydrogen gas, providedthey contain a fair proportion of deuterium.24 The latter has alsobeen modified for the analysis of mixtures of light and heavy ~ a t e r . ~ 5The interferometric method, depending on the different refractiveindices of these two types of waters, has also been modified,26 anda gas-density method involving the use of tt quartz-fibre micro-17 R. Sherr and W.Bleakney, Physical Rev., 1936, 49, 882.19 K. Peters and W. L o b a r , 2. physikal. Chern., 1937, A, 189, 51.2O J. Horiuti and G. Olzamoto, Bull. Chem. SOC. Japan, 1935, 10, 503;G. B. Pegram, H. C. Urey, and J. Huffman, Physical Rev., 1936, 49, 883;E. R. Smith and M. Wojciechowski, J . Res. Nut. Bur. S t a d . , 1936, 17, 841.2 1 E. H. Riesenfeld, Ber., 1935, 68, 1962; E. H. Riesenfeld and T. L.Chang, ibid., 1936, 69, 1302.22 J. S. Anderson, H. V. A. Briscoe et al., J., 1937, 1492 (1499); H.Perperot and F. Schacherl, J. Chim. phydque, 1937, 34, 257.23 Idem, J . Phys. Radium, 1935, 6, 319; K. Fenger-Eriksen, A. Krogh,and H. Ussing, Biochem. J., 1936, 30, 1264; W. H. Hamill, J. Amer. Chem.SOC., 1937, 59, 1152; J. S. Anderson, H. V. A. Briscoe, et al., J., 1937, 1492;H. Fromherz, R.Sonderhd, and H. Thomas, Ber., 1937, 70, 1219.24 A. Farkas, L. FarkBs, and E. K. Rideal, Nature, 1936, 137, 315; K.Wirtz, 2. physikal. Chem., 1936, B, 32, 334; D. D. Eley and J. L. Tuck,Trans. Faraday SOC., 1936, 32, 1425; J. L. Bolland and H. W. Melville, ibid.,1937,33, 1316; G. H. Twigg, ibid., p. 1329; N. R. Trenner, J . Ckm. Physics,1937, 5, 382, 761.D. MecGillavry, Rec. trav. chim., 1937, 56, 330.2s A. Farkas, Trans. Paraday SOC., 1936, 32, 413.26 N. S. Filipova and M. M. Sluckaja, Acta Phy&ochim. U.R.S.S., 1936,51, 131QLASSTONE : NON-RADIOACTIVE ISOTOPES. 35balance has been described.27 The change in the consolutetemperature of the phenol-water system with varying isotopiccomposition of the water has been suggested as a means fordetermining the H/D ratio in liquid water.28 In certain instancesthe relative absorptions at various wave-lengths in the infra-redcan be applied to estimate the isotopic composition of hydrogencorn pound^.^^Properties. Further measurements have been made of thethermal conductivity 30 and viscosity of deuterium gas ; 31 fromthe latter it appears that the effective molecular diameters of thetwo isotopes do not differ by more than 2%.The refraction anddispersion,32 and the compressibility of the gas a t varioustemperatures33 have also been studied. The difference in thevapour pressure of the equilibrium 'mixture of ortho- and para-deuterium and the normal mixture has been determined attemperatures be5ween 15" and 20.4" K.,34 and measurements havebeen made of c, of the two isotopes in the liquid and solid states.35The density, compressibility, and thermal expansion of solidhydrogen and deuterium have been determined at 4.2" 1c.36Observations have been made of the solubility37 of the gases inpalladium, and of their rates of diffusion through heated palladiumand platinum and through an iron The rates ofadsorption on carbon, copper, platinum, and nickel surfaces havebeen ~tudied.3~ The theory of the interaction of atoms and27 N.R. Trenner, J. Amer. Chem. SOC., 1937, 59, 1391 ; see also M. Calvin,Trans. Paraday SOC., 1936, 32, 1428; P. Holemann and K. Clusius, 8.physikal. Chem., 1937, B, 35, 261.28 W. H. Patterson, J., 1937, 1745.2a W.S . Benedict, H. S. Taylor, et al., J . Chem. Physics, 1937, 5, 1.so C. T. Archer, Nature, 1936, 138, 286; G. W. Kannuluik, ibid., 1936,137, 741 ; W. Nothdurft, Ann. Physik, 1937, 28, 157.s1 H. C. Torrey, Physical Rev., 1935, 47, 644; A. B. Van Cleave and 0.Maass, Canadian J. Bee., 1935, 13, B, 384.92 T. Lamen, 2. Physik, 1936,100, 543 ; W. J. C. Om, Tram. Paraday SOC.,1936, 32, 1556.s3 E. Bartholom6, 2. physikal. Chem., 1936, B, 33, 387; K. Schiifer, ibid.,1937, B, 36, 85.34 F. G. Brickwedde, R. B. Scott, and H. S. Taylor, J. Chem. Physics,1935, 3, 653.36 E. Bartholom6 and A. Euckon, 2. Elektrochem., 1936, 42, 547.57 A. Sieverts and G. Zapf, 2. physikal. Chem., 1935, A, 174, 359; A.Sieverts and W. Dam, ibid., 1936, B, 34, 158.3t3 A.Farkas, Trans. Faraday SOC., 1936, 32, 1667; R. Jouan, J . Phys.Radium, 1936, 7, 101 ; P. C. Blokker, Rec. trav. chim., 1936, 55, 979.3Q R. M. Barrer, Trans. Paraday SOC., 1936, 32, 481; R. A. Beebe et al.,J . Amer. Chem. SOC., 1935, 57, 2527; E. B. Maxted and C. H. Moon, J . ,1936, 1542 ; A. Magnus and G. Sartori, 2. physikal. Chem., 1936, A , 175, 329.H. D. Megaw and F. Simon, Nature, 1936,138, 24436 GENERAL AND PHYSICAL CHEMISTRY.molecules with solid surfaces has been worked out and the resultsillustrated by reference to H,, HD, and D, molecules.40Properties* of Deuterium Oxide.-The diamagnetic susceptibility ofliquid deuterium oxide is 0.64 x 10-6 at 20", compared with0.72 x for water,41 but the surface tensions are identicalwithin O*05~0,42 contrary to results reported previously.Atordinary temperatures the vapour pressure of heavy water is lessthan that of light water-hence the possibility of separation bydistillation-but the difference diminishes as the temperature israised : it is estimated that at 224" the values would be identical.The latent heat of vaporisation of D,O exceeds that of H,O, buthere also increase of temperature decreases the differen~e.4~ Thelatent heats of fusion are in the opposite direction, the values inmixtures of light and heavy water being expressed by L 5 79.67 -4.38n2 cals. per g., where 12, is the mole-fraction of D,0.44 It hadbeen stated that the isotopic composition of ice which separatesfrom water is the same as that of the water itself ,45 but this has beenshown to be incorrect : 46 the solidus and liquidus curves are,however, not far apart, the maximum separation being 0.02" for aliquid containing 42% of D20.The specific heat of liquid heavywater is appreciably greater than that of ordinary water, thedifference being largest at low temperatures. The mean specificheat of D,O between 4" and 26" is 1.018 cals.47 New determinationshave been made of the viscosity of liquid D,O, which is found tobe greater than that of H20,48 and of the densities of mixtures oflight and heavy water. It appears that there is no volume changeon mixing, and that the system is ideal, as is to be expected; from40 5. E. Lennard-Jones and A. F. Devonshire, Proc. Roy. SOC., 1936, A,156, 16.4 1 F.E. Hoare, Nature, 1936, 137, 497; (Miss) V. C. G. Trew and J. F.Spencer, ibid., pp. 706, 998; V. Nehra and M. Qureski, Current Sci., 1937,5, 533 ; H. P. Iskenderian, Physical Rev., 1937, 51, 1092.42 H. Flood and L. Tronstad, 2. physikal. Chern., 1936, A , 175, 347; H.Lachs and I. Minkow, Rocz. Chem., 1937, 17, 363 ; G. Jones and W. A. Ray,J . Chern. Physics, 1937, 5, 505; J. Timmermans and H. Bodson, Cornpt.rend., 1937, 204, 1804.43 F. T. Miles and A. W. C. Menzies, J. Amer. Chem. SOC., 1936, 58, 1067;E. H. Riesenfeld and T. L. Chang, 2. physilal. Chern., 1936, B, 33, 120,127.44 0. Redlich and J. Zentner, Monatsh., 1936, 68, 407; E. A. Long andJ. D. Kemp, J . Arner. Chem. SOC., 1936, 58, 1829.45 M. Deielih, 2. anorg. Chem., 1935, 225, 173.46 A.Eucken and K. Schafer, ibid., p. 319.4 7 R. S. Brown, W. H. Barnes, and 0. Maass, Canadian J . Res., 1935,13, B,18 G. Jones and H. J. Fornwalt, J. Chem. Physics, 1936, 4, 30; W. N.167; A. Ferguson and A. H. Cockett, Nature, 1936, 138, 842.Baker, ibid., p. 294GLASSTONE : NON-RADIOACTIVE ISOTOPES. 37the known densities, dzP, of pure H20 (0.99705) and of pure D,O(1.10466), it is shown that n,,, = 9.235AS/(l - 0.0309AS), wherenDeo is the mo1.-fraction of D20 in a mixture and AX is equal to- d-.)/dH20, the d values being for 25" compared withordinary water a t 4'?9 The density of liquid deuterium oxide atvarious temperatures and the volume change on freezing havebeen studied; the influence of pressure on the freezing point ofdeuterium oxide is 0.00705" per kg./cm.z, which is approximatelythe same as for ~ater.~O The apparent molar volume of deuteriumoxide dissolved in dioxan is about 0.5% less than that for water,in agreement with theoretical e~pectation.~l The refractive indexof 99.2y0 D20 vapour for light of A 5462-23 A.is 1.0002501 comparedwith 1.0002527 for H,O; the dispersion has also been studied.52The difference in the ionic products of the two forms of water,mentioned in the last report, has been confirmed, the ratioKHso/KDt0 being about 5-5 at 25".53 In agreement with previouswork, it is found that replacement of water by deuterium oxideraises the upper and depresses the lower consolute temperatures ofa binary liquid system.54 The adsorption of the vapour of heavywater on active charcoal has been investigated.55Deuterates.-The dissociation pressures of the deuterates of anumber of salts, vix., CuSO,, 5D20, Na,SO,, 10D20, MgSO,, 7D20,SrCl,, 6D20, CoCl,, 6D,O, NiCl,, 6D20 and NaBrz, 2D,O, have beenmeasured over a range of temperatures.The deuterates havelower vapour pressures than the corresponding hydrates, and theheat changes involved are also lower ; as far as has been examined,the transition points of deuterates, with the exception ofNa,S04, 10D20, appear to be lower than for the correspondinghydrates.56 The colour of CuS04, 5D,O is considerably lighterthan that of CuSO,, 5H20, and a similar difference is observed insolutions in heavy and light water, respectively, a t equal concen-tration~.~' Deuterates of the inert gases, vix., Kr, 6D20 and49 L.G. Longsworth, J. Amer. Chem. SOC., 1937, 59, 1483.50 J. Timmermans et al., Conzpt. rend., 1936, 202, 1061.51 R. A. Robinson and R. P. Bell, Trans. Paraday Soc., 1937, 33, 650.62 C. Cuthbertson and M. Cuthbertson, Proc. Roy. SOC., 1936, A , 155,213.53 W. F. K. Wynne-Jones, Trans. Faraday Soc., 1936, 32, 1397; H.Erlenmeyer and A. Epprecht, Helw. Chim. Ada, 1936, 19, 677, 1292.64 J. Timmermans and G. Poppe, Compt. rend., 1935,201, 608.55 A. King and C. G. Lawson, Trans. Paraday SOC., 1936, 32, 478; K. Arii,Bull. Inst. Phys. Chem. Res. Japan, 1937, 16, 749.58 H. Perperot and F. Schacherl, J. Phys. Radium, 1935, 6, 439; J. R.Partington and (Mrs.) K. Stratton, Nature, 1936, 137, 1075; F.Schacherland 0. BBhounek, ibid., 1936, 138, 406; J. Bell, J . , 1937, 459.5 7 Idem, Nature, 1936, 137, 53438 GENERAL AND PIIYSICAL CHEMISTRY.Xe, 6D20, have been prepared; they are said to resemble thecorresponding unstable hydrates.58Solutions in Heavy Water.-The solubilities of various salts havebeen measured in heavy water and compared with the values inordinary water : in general, the former are the lower when referredto the same number of mols. of s0lvent.5~ A number of studiesare recorded of heats of dissolution and of dilution of electrolytesin light and in heavy water. The heat absorbed on dissolution inthe latter is greater than for the same salt in ordinary water, thedifferences being attributed mainly to differences in the heats ofsolvation of the ions.In dilute solution the integral heats ofdilution are independent of the isotopic composition of the water,but at higher concentrations the values become greater, numerically,in passing from ordinary to heavy water.60 The quinhydroneelectrede has been applied to the measurement of acidity in heavywater, and the dissociation constants of salicylic and acetic acidsand of quinol have been determined; the values, like the ionicproduct, are less than in normal water.61 The whole subject ofionic equilibria in H20-D,O mixtures has been considered fromthe theoretical standpoint, especially with reference to thequinhydrone and the hydrogen electrode, and the dissociation ofacids.62 The dissociation constant of acetic acid has also beendetermined from conductance measurements with potassiumacetate in deuterium oxide ; the product of the equivalentconductance a t infinite dilution and the viscosity, i.e., the Waldenconstant, changes by nearly 2% in passing from normal to heavywater.Similar results have been obtained with potassiumchloride solution^.^^ Determinations have been made of thetransport numbers and conductances of lithium, sodium, potassium,and hydrogen chlorides in heavy water, and the ionic conductancesat infinite dilution have been estimated. The value for thechlorine ion varies in a linear manner with the mo1.-fraction of D,O58 M. Godchot, (Mlle.) G. Cauquil, and R. Galas, Compt. rend., 1936, 202,759.59 F. T. Miles, R. W. Shearman, and A.W. C. Menzies, Nature, 1936, 138,121; R. W. Shearman and A. W.. C . Menzies, J . Amer. Chm. Soc., 1937,59, 185; F. T. Miles and A. W. C. Menzies, ibid., p. 2392.60 E. Lange and W. Martin, 8. Elektrochem., 1936, 42, 662; 2. physikal.Chem., 1937, A , 178, 214; 179, 427; 180, 233; W. Birnthaler and E. Lange,2. Elekt.rochem., 1937, 43, 643; for mmmary, see E. Lange, ibid., 1938, 44,31.61 IT. K. LaMer, and S. Korman, Science, 1936, 83, 624; J. Amer. Chm.SOL, 1936, 58, 1396; J. P. Chittum and V. K. LaMer, ibid:, 1937, 59, 2425.62 W. H. Hamill, ibid., p. 1492; G. Schwarzenbach, 8. Elektrochem., 1938,44, 46.63 V. K. LaMer and 5. P. Chittum, J. Amer. Chem. Soc., 1936, 58, 1642ClLASSTONE : NON-RADIOACTIVE ISOTOPES. 39in the water, but for the hydrogen ion there are considerabledeviations indicating a complex conductance me~hanism.~~ Potas-sium acetate and acetic acid have been electrolysed in heavy water,but the resulting ethane contained very little deuterium.65 Thehigher overvoltage of hydrogen in deuterium oxide at a mercurycathode has been confirmed; 66 the importance of the results inconnexion with the theory of overvoltage is considered elsewhereOther Deuterium Compounds.-The refractive indices of gaseousD,Se,67 ND,, and DC168 have been measured and compared withthe values for the analogous hydrogen compounds; the former aredways slightly less than the latter.The melting points andtransition points of CD,, D,S, and D,Se have been observed,Gg andtransformations in the solid state studied optically and by X-raymethods.' 0 Solid tetradeuteroammonium chloride, like its hydrogenanalogue, undergoes changes in its lattice dimensions at lowtemperatures, the respective transition points being - 24" and - 30°.71 The critical temperatures of various simple deuteriumcompounds have been determined and found to be less than for thecorresponding hydrogen co~npounds.~~ A number of organicdeuterium compounds have been prepared andHomogeneous Exchange Reactions .-Investigations have beenmade of exchange reactions involving isotopes of hydrogen and thehalogen acids; heats of reaction and equilibrium constants havebeen e~aluated,'~ and the results found to be in agreement with(p. 109).64 L. G. Longsworth and D. A. MacTnnes, J .Amer. Chem. BOG., 1937, 59,1666; J. P. Chittum and V. K. LaMer, Zoc. cit., ref. (61) ; see also, V . K. LaMer,Chem. Reviews, 1936, 19, 363.66 K. Erlenmeyer and W . Schoenauer, Helv. Chim. Acta, 1937, 20, 222;P. Holemann and K. Clusius, loc. cit., ref. (27)-66 J. Nov&k, Coll. Czech. Chem. Comm., 1937, 9, 237.67 0. E. Frivold, 0. Hassel, and T. Skjulstad, Physikal. Z., 1936, 37, 134.68 0. E. Frivold, 0. Hamel, and S. Rustsd, ibid., 1937, 38, 191.6Q A. Kruis, L. Popp, and K. Clusius, 2. Elektrochem., 1937, 43, 664. '* A. Kruis and K. Clusius, Z . physikal. Chem., 1937, B, 38, 156; PhysiEal.Z., 1937, 38, 510; E. Justi and H. Nitka, ibid., p. 514.71 A. Smits, G. J. Muller, and F. A. Kroger, 8. physilcal. Chem., 1937, B,38, 177 ; I. Nittrt and K.Suenaga, Sci. Papers Inst. Phys. Chem. Res. Tokyo,1937, 32, 83; J. Weigle and H. SaYni, Arch. Sci. phys. nut., 1937, 19, Suppl.28-29.72 H . Kopper, 8. physikal. Chem., 1936, A, 175, 469.78 For summary, see H. Erlenmeyer, 2. Elektrochem., 1938, 44, 8 (9); seealso Arm. Repwta, 1936, 33, 228, 291.74 P. C. Cross and P. R. Leighton, J . Chem. Physics, 1936, 4, 28; A. F.Kapustinsky, J . Amer. Chem. Soc., 1936, 58, 460; K. Wirtz, 2. physikal.Chem., 1936, B, 31, 309; Physikal. Z., 1936, 37, 165; J. R. Partington andR. P. Towndrow, Nature, 1937,140, 15640 GENERAL AND PHYSICAL CHEMISTRY.those calculated from spectroscopic data.75 The exchange reactionsbetween the isotopic forms of hydrogen and water, hydrogensulphide and water, and hydrogen and ammonia have also beenthe subject of theoretical and experimental studies.76 Theequilibrium constant and velocities of direct and reverse reactionsin the exchange between ethyl alcohol and HDO have beenmeasured, and from the results it is concluded that the reactionproceeds ionically.77 Atomic deuterium reacts with saturatedaliphatic hydrocarbons, e.g., methane, ethane, etc., hydrogenatoms being replaced by those of deuterium; the energies ofactivation of such processes have been measured, and the resultsapplied to some problems of reaction mechanism and energies oflinkage~.7~ It has been confirmed that in aqueous solutions thereis complete exchange between the hydrogen of the ammino- andaquo-groups of complex cobaltammines and the deuterium of heavywater; 79 the mechanism of the exchange has been discussed.**The hydrogen in hypophosphorous acid exchanges almost com-pletely with deuterium in deuterium oxide solution, but thedeuterium in the salt Ba(D,PO,), does not exchange with thehydrogen in ordinary water after several hours.81 Some workersclaim that the hydrogen atoms in alkali acetates can undergoexchange to a small extentYs1 whereas others 82 say that noapparent exchange occurs.Investigation of the reaction betweenacetylene and water has been continued; heats of reaction andequilibrium constants have been measured, and the latter havealso been calculated from spectroscopic data.s3 A number of75 See Ann. Reports, 1935, 32, 66.7 6 T. Jones and A. Sherman, J. Chem.Physics, 1937, 5, 375; K. Wirtzand K. F. Bonhoeffer, 2. physikal. Chem., 1936, A, 177, 1; K. Wirtz, ibid.,1935, B, 30, 289; A. Farkas, J., 1936, 26; P. A. Small, Trans. Paraday SOL,1937, 33, 820.7 7 W. 5. C. Orr, ibid., 1936, 32, 1033; see, however, J. C. Jungers andK. F. Bonhoeffer, 2. physikal. Chem., 1936, A , 177, 460,7 8 E. W. R. Steacie and N. W. F. Phillips, J . Chem. Physics, 1936, 4, 461;E. W. R. Stcacie, Canadian J . Res., 1937, 15, B, 264; N. R. Trenner, K.Morikawa, and H. S. Taylor, J. Chem. Physics, 1937, 5, 203; cf. this vol.,70 F. W. James, J. S. Anderson, and H. V. A. Hriscoe, Nature, 1937, 139,109; J. Horiuti and G. Okamoto, Sci. Papers Inst. Phys. Chem. Res. Tokyo,1937, 31, 205; G. Qkamoto, J. Pac. Sci. Hokkaido Imp. Univ., 1937, 111, 2,818.80 J. S.Anderson, N. L. Spoor, and H. V. A. Briscoe, Nature, 1937, 139, 508.81 H. Erlenmeyer, W. Schoenauer and G. Schwarzenbach, Helv. Chim.82 S . Liotta and V. K. LaMer, J . Amer. Chem. SOC., 1937, 59, 946.83 L. H. Reyerson and B. Gillespie, ibid., 1936, 58, 282; 1937, 59, 900;p. 49.Actcc, 1937, 20, 726.K. Hirota and G. Okamoto, Bull. Chem. Soc. Japan, 1936, 11, 349GLASSTONE : NON-RADIOACTNE ISOTOPES. 41papers dealing with exchange reactions involving organic com-pounds have appeared,84 some of which are of physicochemicalinterest .85Heterogeneous Exchange Reactions.-Experiments on the catalysedexchange reactions between the isotopes of hydrogen in the gaseousform and liquid water, e.g., D, + H,O =+ HD + HDO andHD -+ H,O + H, + HDO, have been continued, and the subjecthas also been considered from the theoretical standpoint, as it hassome bearing on the problem of the electrolytic separation factor.It appears that the rate of atomisation of molecular hydrogen isan important factor in determining the rate of the process, butother factors may also be operative.The heterogeneous reactionsbetween gaseous hydrogen and methyl and ethyl alcohol, and alsoprobably with other organic compounds, appear to involve similarmechanisms. 86 Deuterium and ammonia gas undergo exchangeon iron catalysts ; the reaction has been investigated between 160"and 230", and shown to proceed in the adsorption layer as follows :NH,+ NH, + H, D,+ ZD, D + H + HD and D + NH,--+ NH,D, the last stage being the one which determines theover-all rate of the process.87 Studies are being made of theexchange between deuterium and gaseous paraffin hydrocarbonson nickel catalysts ; from the results, information is being obtainedconcerning the activation of particular linkages of the hydrocarbonon the catalyst surface.88Other Properties of Deuterium Compounds.-The spectroscopy ofdeuterium compounds continues to be a subject of investigation ;this has been already considered in these Reports,s9 and a furtherdiscussion must be left until a comprehensive treatment is possible.The photochemistry and kinetics of reactions involving deuteriumand its compounds are considered on pp.68 and 49; referencemay also be made to a previous and to valuablesummaries .9184 For complete review, see C.K. Ingold and C. L. Wilson, 8. Elektrochem.,85 A. E. Brodski, Trans. Faraday Soc., 1937, 33, 1180.86 A. Farkas, ibid., 1936, 32, 922; D. D. Eley and M. Polanyi, ibid., p.1388; M. Calvin, ibid., p. 1428; J. Horiuti and G. Okamoto, ibid., p. 1492;A. Farkas and L. Farkas, ibid., 1937, 33, 678, 827; G. Okamoto, K. Hirota,and J. I-Ioriuti, Sci. Papers Inst. Phys. Chem. Res., 1936, 29, 223; 30, 151 ;1937, 31, 211.1938, 44, 62 ; see also Ann. Reports, 1936, 33, ?91.87 A. Farkas, Trans. Paraday Soc., 1936, 32, 416.88 K. Marikawa, H. S. Taylor et at., J. Amer. Chem. Soc., 1936, 58, 1445,89 Ann. Reports, 1935, 32, 64; 1936, 33, 53.01 0. Reitz, 2. Elektrochem., 1938, 44, 72; K. H. Geib, ibid., p.81.1795; 1937, 59, 1103.Ibid., pp. 92, 9842 GENERAL AND PHYSICAL CHEMISTRY.Tritiwm-Since the claim to have concentrated tritium, i.e., thehydrogen isotope of mass 3, in water was made over two years ago,there have been no further developments in this field; from acritical review of the whole problem, however, it appears that theevidence for the existence of tritium in Nature is open to seriousdoubt?2Oxygen. Isotopes.-The important discovery has been made 93and confirmedg4 that oxygen from the air is richer in the heavierisotopes than is the oxygen in ordinary water; the difference inatom weights is 0-00011 unit. Water obtained from atmosphericoxygen is thus about 7 p.p.m. heavier than lake, sea, or river waterhaving the same isotopic ratio of hydrogen.The differenceappears to be due to the exchange reaction 2H21s0(Z) + 1602(g)1802(g) + 2H2l6O(Z), for which the equilibrium constant is 1.012 a t25°,95 so that the ratio 1sO/160 is greater in the gas phase, i.e., theatmosphere, than in the liquid, i.e., water. Normally, a relativelyhigh temperature and a catalyst are required for this equilibriumto be e~tablished,~~ but it is possible that in Nature it may beattained relatively rapidly in the stratosphere under the influenceof ultra-violet radiation from the ~ ~ 1 1 . ~ 7 Another possibility isthat the excess l80 in the atmosphere may result from the exchangebetween carbon dioxide and water, leading to excess of the heavyoxygen isotope in the and this is subsequently liberatedas molecular oxygen by the photosynthetic action of plants.99The two isotopic forms of water, H,160 and H21S0, have a slightdifference of vapour pressure, and this has been utilised to bringabout a partial separation in a specially designed fractionatingcolumn consisting of seven 5-ft.lengths, each fitted with 87 fixedand 87 rotating conical plates. A steady supply of watercontaining 2.5% of H2lsO is expected.1 The ready availability of92 (Lord) Ruthsrford, Nature, 1937, 140, 303.93 M. Dole, J. Amr. Chem. Soc., 1935, 57, 2731; J . Chem. Physics, 1936,4, 268, 778; N. Morita and T. Titmi, Bull. Chem. SOC. Japan, 1936, 11, 36,414.94 C. H. Greene and R. J. Voskuyl, J. Amer. Chem. Soc., 1936, 58, 693;W. H. Hall and M. L. Johnston, ibid., p.1920; T. 0. Jones and N. F. Hall,ibid., 1937, 59, 259; E. R. Smith and H. Matheson, J. Res. Nu). Bur. Xtand.,1936, 17, 625.O6 Ann. Reports, 1935, 32, 52.g6 N. Morita and T. Titani, Bull. Chm. SOC. Japan, 1937, 12, 104; T. 0.97 H. C. Urey, quoted by M. Dole, J. Chem. Phy&s, 1936, 4, 268 (272).Q8 Ann. Reports, 1935, 32, 62.Jones and N. F. Hall, loc. cit., ref. (94).C. H. Greene and R. J. Voskuyl, loo. cit., ref. (94).J. R. Huffman and H. C. Urey, Id. Eng. Chem., 1937,29, 531 ; see alsaS. C. Datta, J. N. E. Day, and C. K. Ingold, J., 1937, 1968 (1969)WYNNE-JONES : CH.EMICAL HINE'J!IUS. 43water enriched with respect to I80 will encourage further studiesof oxygen-interchange reaction in solution.2Other Isotopes.-Considerable enrichment of the heavier isotopeof carbon (13C) in methane, of nitrogen (15N) in nitrogen gas, andof the lighter isotopes of argon (36A and 38A) has been obtainedby use of the Hertz type of diffusion apparat~s.~ By allowing finedrops of lithium amalgam to fall repeatedly through a long columncontaining lithium chloride dissolved in ethyl alcohol, or lithiumbromide in alcohol-dioxan, exchange of the lithium between thetwo phases occurs, with the result that the isotopic ratio 'Li/6Li ischanged from 11.6 to 5.1 at the bottom of the column where thelithium in the amalgam is extracted by the solution.4 A similarenrichment has been observed in the direct electrolysis of aqueouslithium hydroxide,5 the 7Li isotope remaining in the electrolyte,although failure is recorded with a lithium chloride solution and acathode of circulating mercury.6 Passage of lithium and ammoniumchlorides through a column of zeolite results in an increase in theproportion of the heavier isotope of lithium and of the lighterisotope of nitrogen, respectively, in the solutions ; this is probablythe result of preferential adsorption of the other isotope by thezeolite.5 By means of chemical exchange reactions, e.g., betweencarbon dioxide and aqueous potassium hydrogen carbonate in thepresence of carbonic anhydrase, and between ammonia and aqueousammonium sulphate or nitrate, enrichment of the isotopes 1sC and15N, respectively, has been obtained.' The best results have beenrecorded with ammonium sulphate, a 6.5-fold increase in theproportion of 15N being achieved.S. G.3. CHEMICAL KINETICS.The two main aspects of the study of chemical reactions arethe elucidation of their kinetics and the interpretation of theirmechanisms in terms of the properties of the reacting molecules.These problems may be treated separately, but the interpretationof mechanisms is dependent upon a correct analysis of the kinetics ofCf. S. C. Datta, J. N. E. Day, and C. K. Ingold, J., 1937, 1968 (1969);E. Blumenthal and J. B. M. Herbert, TTans. Farday Soc., 1937, 33, 849.D. E. Wooldridge and W. R. Smythe, Phy&al Rev., 1936, 50, 233;D. E. Wooldridge and F. A. Jenkins, ibid., 1936, 49, 404, 704; H. Barwickand W. Schiitze, 2. Physik, 1937,105, 395.4 G. N. Lewis and R.T. Macdonald, J. Amer. Chem. Soc., 1936,58, 2519.6 T. I. Taylor and H. C. Urey, J. Chem. Phyaics, 1937, 5, 597.6 G. Champetier and P. Regnault, Bull. SOC. chim., 1937, 4, 592.7 H. C. Urey et al., J . Chem. Physics, 1936, 4, 622; 1937, 5, 856; J. Amer.Chem. Soc., 1937, 59, 140744 GENERAL AND PHYSICAL CHEMISTRY.reactions, and also upon the use of an adequate theory for theformulation of reaction rates. The general theory of the rates ofelementary reactions, which has been reported in previous years,lhas been the subject of recent discussions held by the ChemicalSociety 21 3 and the Paraday Society,4 in which various diflicultieshave been cleared away. The theory, which can be most simplystated in the formk* = K K ~ . kT/hwhere k* is the specific reaction rate constant, K$ the equilibriumconstant between the activated complex and the reactants, k theBoltzmann constant, T the absolute temperature, h is Planck’sconstant and K is the transmission coefficient, involves twoassumptions, vix., (1) that the equilibrium number of activatedcomplexes is maintained throughout the course of the reaction, and(2) that for the motion of the nuclei quantum effects may be neglectedor regarded as corrections to the classical treatment. I f K is takenas unity, this is a third assumption which must be considered.Attention has been called to the first assumption by variousauthors 5s 6 who doubt its validity : the difficulty was first raised byR.H. Fowler 7 with regard to kinetic-theory calculations of reactionrates, but it was shown by L.S. Kassel that, for approximatelyequal molecular masses of the reactants, the disturbance of theMaxwell distribution by reaction would usually be of the order of0.1%. A more general argument is that k* for elementarybimolecular reactions is constant throughout the reaction andindependent of the pressure ; further, for reactions reaching anequilibrium, where it has been possible to study both the forwardand the back reactions, the ratio of the two rate constants hasbeen found to agree with the equilibrium constant. It is extremelyunlikely that in ordinary liquids, where the solvent molecules willhelp t o maintain the Maxwell distribution, there will be any greaterdivergence than in gases, and we may therefore regard the firstassumption as valid for all ordinary reaction^.^The second assumption is generally accepted, and it seems probablethat, except for hydrogen atoms, deviations from classical behaviourAnn.Reports, 1935, 32, 89; 1936, 33, 86.2 M. Polanyi, J . , 1937, 629.4 Trans. Paraday SOC., 1938, 34, 1.5 E. A. Guggenheim and J. Weiss, ibid., p, 57.6 R. H. Fowler, ibid., p. 24.7 “ Statistical Mechanics,” 1929, 461.C. N. Hinshelwood, ibid., p. 635.Physical Rev., 1930, 35, 261.This is shown in yet another way by J. A. Christiansen (Trans. ParadaySOC., 1938, 34, 73) from his theory of intramolecular diffusion, 2. physikal.Chem., 1936, B, 33, 145; 1937, B, 37, 374WYNNE-JONES : CHEMICAL KINETICS. 45are not significant.lO* l1 The evaluation of the transmissioncoefficient is not so easy : a t sufficiently low temperatures we mayregard it as unity for all reactions, but, as E.Wigner 11 has shown,if the potential surfaces are very complicated, the value of K mayfall much below unity. If the reaction is not “ adiabatic,” i.e.,if during the motion of the nuclei the electrons do not remain inthe lowest quantum state, there will also be a decreased rate whichmay be treated as a small transmission coefficient.12The general theory of reaction rates can be applied in variousways and the particular mode adopted depends upon the informationavailable with regard to molecular properties and potential-energysurfaces. For certain gaseous reactions, it has been possible to carryout a detailed analysis which leads to the calculation of the rate ofthe reaction from the properties of the reacting m0lecules.1~ Forother reactions, in particular those occurring in solution, it is moreconvenient to employ a thermodynamic formulation * and to assignto the activated complex an activity coefficient which may becompared with those of other molecular species and hence enablereaction mechanisms to be deduced.This is analogous to theprocedure which has proved so useful in the study of the equilibriumproperties of solutions, and has the merit of emphasising that anunderstanding of equilibria is essential for an interpretation ofreaction rates.A striking feature of the work under review is the increasingrealisation of the importance of equilibrium studies for the interpret -ation of the rates of reactions.For chain reactions and otherreactions showing complex kinetic behaviour it is necessary to useelaborate kinetic formulations, but for the majority of reactionsfollowing simple kinetic laws any abnormality in the rate is reflectedin the equilibrium data, and this makes it in the highest degreeimprobable that explanations involving specifically kinetic factorshave any significance.A. E. Stearn and H. Eyring l4 have discussed the mechanism ofthe Menschutkin reaction from this point of view, and have shown10 R. P. Bell, Proc. Roy. SOC., 1933, A, 139, 466.11 Trans. Faraday Xoc., 1938, 34, 29.12 A. E. Stearn and H. Eyring, J . Chem. Physics, 1935, 3, 778.13 Ann.Reports, 1936, 33, 89-91.14 J . Chem. Physics, 1937, 5, 113.* This has given rise to the unfortunate expression “the quasi-thermo-dynamic theory of reactions.’’ There is no qualification to be attached tothe thermodynamic formulation of the general theory of reaction rates; ifcompetently done, the thermodynamic expressions are precise and can beapplied with complete confidence. The theory itself is not, of course, atheorem in thermodynamics, and should not be so described. In any casethe prefix “ quasi- ” is meaningless when applied to thermodynamics46 GENERAL AND PHYSICAL CHEMISTRY.that the activity coefticient of the activated complex varies with thedielectric constant of the medium in the way to be expected for amolecule with a very high dipole moment ; they have also estimatedthe free energy of proton transfer from one water molecule to anotherfrom the data for the mobility of the hydrogen ion and for thedispersion of the dielectric constant of ice.E. A. Guggenheim l6has written a valuable account of the thermodynamic relations foractivated complexes, and the use of the correct forms of theserelations should go far to remove misunderstandings.E. Wigner 16 has considered the association of atoms by three-body collisions, and has pointed out that in such a case there is noactivation energy and that the transition state is not so muchthe passage through a surface in space as the passing of the relativeenergy of the atoms through the value zero. He is able to fixupper limits for the rates of such reactions, and these values agreefairly well with the results of E.Rabinovitsch and W. C. Wood 1 7on the recombination of iodine atoms. H. Gershinowitz 18 has usedthe energy surfaces constructed for the interaction of three hydrogenatoms in a, consideration of the transfer of energy in molecularsystems : the probability of energy transfer is dependent upon thestate of excitation of the reagents, and we thus have quite differentrelative efficiencies of gases for energy transfer in the dispersion ofsound and in unimolecular reactions.Gas Reuctiorns.-F'resh examples of unimolecular reactions havebeen found with features similar to those already investigated:amongst those investigated are the cis-tr~~s-isomerisation ofp-cyanostyrene,l9 the decomposition of tert.-butyl halides,2* thedecomposition of methylene diacetate, dipropionste, and dibutyrateand of allied 22 and the decomposition of benzylidene-azine and of a-a~otoluene,~~~ 24 of ethyl and n-propyl nitrites 25 andof tetramethylsilicon .26The status of many unholecular reactions was questioned someyears ago by F.0. Rice and K. F. Her~feld,~' who suggested thatthey are chain reactions involving free radicals. The presence of1 5 Trans. Faraday SOC., 1937, 33, 607. l6 J . Chem. Physics, 1937, 5, 72Q.17 Ibid., 1936, 4, 497. Is Ibid., 1937, 5, 54.19 G. B. Kistiakowsky and W. R. Smith, J . Amer. Chem. SOC., 1936, 58,20 G. B. Kistiakowsky and C. H. Stauffer, ibid., 1937, 59, 165.21 C. C. Cof€in and W.B. Beazley, Canadian J . Res., 1937, 15, B, 229.22 C. C. Coffin, J. R. Dacey, and N. A. D. Parlee, ibid., pp. 247, 254, 260.23 A. Williams and A. S. C. Lawrence, Proc. Roy. SOC., 1936, A , 156, 444.24 Idem, ibid., p. 455.25 E. W. R. Steacie and S. Katz, J . Chem. Phy&x, 1937, 5, 125.26 D. F. Helm and E. Mack, J . Amer. Ohern. Soc., 1937,59, 60.27 Ibid., 1934, 56, 284.2428WYNNE-JONES CHEMICAL KINETIUS. 47free radicals in these reacting systems has been shown by Pease 28* 29and by C. J. M. Fletcher and G. K. Rollef~on,~O and L. A. K. Staveleyand C. N. Hinshelwood 31 have made a detailed study of the effectof nitric oxide on the kinetics of these reactions. Nitric oxide issupposed to act by removal of free radicals, aiid the inhibitedreaction is regarded as the simple decomposition : for the ethers,aldehydes, and ketones, the mean chain length, defined as the ratioof the uninhibited and inhibited reactions, is small, and this isregarded as indicating that only a small proportion of the primaryacts yields radicals but these give rise to long chains.Since theinhibited reaction shows the same kinetic behaviour as the un-inhibited, conclusions previously drawn as to the nature of thesereactions are substantially On the other hand, M. W.Travers and his collaborators 33 have carried out an extensive seriesof detailed analyses of the reacting systems and conclude that thewhole course of these reactions is far too complex for the manometricmethod of following the reaction rate to yield results of significance.For the decomposition of dimethyl ether, P.3’. Gay and M. W.Travers 34 find that the effect of increasing additions of nitric oxideis to suppress completely the normal decomposition and to set upanother process of oxidation. It is evident that much more detailedstudy is required before our knowledge of these processes can beregarded as satisfactory.Reactions between nitric oxide and oxygen, chlorine, or bromineare the best known examples of third-order reactions in the gaseousstate, but there has always been discussion about their mechanism.R. H. Crist and G. M. Calhoun35 have studied the oxidation ofcarbon monoxide in presence of nitric oxide, and claim from theirresults at low oxygen pressures that the rate-determining step isthe formation of nitrogen trioxide from nitric oxide and oxygen;other authors have regarded the molecule (NO), as the reactingspecies.W. Krauss and M. continuing the work ofM. Bodenstein’and W. have shown that the reaction2N0 + C1, = 2NOC1 is accurately of the third order, and theirresults are of great importance, because, when combined with thedata of G. Waddington and It. C. Tolman3s for the bimolecular28 R. N. Pease, J . Arner. Chern. SOC., 1937, 59, 425.29 L. S. Echols and R. N. Pease, ibid., p. 766.30 Ibid., 1936, 58, 2129.31 Proc. Roy. SOC., 1937, A , 159, 192.33 Trans. Faraday Soc., 1937, 33, 1342.3 5 J . Chem. Physics, 1937, 5, 301.36 2. physikal. Chem., 1937, A , 178, 245.37 Ibid., 1936, A, 175, 294.3 8 J .Arner. Chem. Soc., 1935, 57, 689.32 J., 1937, 1568.s p Ibid., p. 75648 GENERAL AND PHYSICAL CHEMISTRY.decomposition of nitrosyl chloride, they give with high accuracy-J. K. Dixon’s 39 values for the equilibrium constants.Combustion of Gases.-The phenomenon of combustion is charac-terised by considerable kinetic complexity and marked dependenceupon the nature and dimensions of the containing vessel; never-theless, considerable progress has been made as the result of carefulexperimentation and the detailed working out of reaction schemes,particularly following the work of N. Semen~ff.~O R. G. W. Norrishand S. G. Foord 41 have examined the combustion of methane andshown that the marked induction period followed by a gradualincrease in the reaction velocity, the almost complete inhibition ofthe reaction by packing the vessel, and the variation of the ignitiontemperature with pressure can all be accounted for on the atom-chain hypothesis. It is assumed that oxygen atoms are producedat the surface by some such reaction asCH4 + 0, = HCHO + H,O; H*CHO + 0, = H*C02H + 0I J.H20 + COthe formaldehyde concentration then steadily increases by a straightchain of the type0 + CH, = CH, + H,O; CH, + 0, = H*CHO + 0Formaldehyde molecules may be occasionally removed by oxidationby molecular oxygen, thus causing chain-branching and allowingan exponential growth of the formaldehyde concentration. Theultimate removal of formaldehyde from the system is assumed tooccur by the reactionHCHO + 0 = CO + H2Owhich causes a decrease in the effective chain-branching factor andmakes the rate of combustion reach a steady value. As the pressureis increased, the rate increases until the system is unable to dissipatethe heat of reaction and ignition occurs.This scheme is simple and seems to account for most of the facts,but G.von Elbe and B. Lewis42 consider modification necessaryin order to explain the maximum in the rate which is observed atabout 350” for all paraffin hydrocarbons except methane, also thephenomenon of “cool” flames, and the production of methylalcohol in large amounts during the oxidation of propane. The39 2. physikal. Clz,em., 1931, Bodenstein Festband, p. 679.40 “ Chemical Kinetics and Chain Reactions,” Oxford, 1934.41 Proc.Roy. SOC., 1936, A, 157, 503.42 J . Arner. Chern. SOC., 1937, 59, 976WYNNE-JONES : CHEMICAL EINETICS. 49scheme suggested by these authors involves hydroxyl-radical chains,and for the oxidation of methane they suggestOH + CH, = CH, + H2OCH, + 0 2 = HGHO + OHfollowed byOH + HCHO = HCO + H,OHO, + H*CHO = CO + H,O + OHThis leads to much the same results as the treatment of Norrishand Foord, but in addition affords an explanation of the formationof methyl alcohol, since with higher hydrocarbons CH,R radicalswill be formed and these may react with oxygen giving first peroxideradicals and then methyl alcohol. The luminescence is ascribedto the breakdown of radicals, yielding formaldehyde with very largeexcess of energy.Numerous other investigations have been carried out on thecombustion of hydrocarbons 43 and the hydrogen-oxygen reaction.44Interesting results have been obtained from studies of the exchangereactions between hydrogen and deuterium atoms and variousmolecules containing hydrogen.A. Farkas and H. W. Melville45examined the mercury-sensitised exchange reactions of deuteriumwith ammonia, methane, and water, and compared the rates withthe absolute intensity of the light and with the rate of the ortho-para-hydrogen conversion in the reacting mixture which enabled acalculation of the concentration of hydrogen or deuterium atoms.The energies of activation for the reactions of deuterium atoms withmethane, ammonia, and water were found to be 13,11, and 7 kg.-cals.respectively.The value for methane is confirmed by the work ofE. W. R. S t e a ~ i e , ~ ~ but the measurements of H. S. Taylor and hiscollaborators 47 on the methane reaction, using the mercury reson-ance radiation and also a Wood's discharge tube for producinghydrogen atoms, suggest that the reaction is complex and that theHCO + 0, = HO, + CO43 B. V. Aivazov and M. B. Neumann, J . Phys. Chem. Russia, 1936, 8, 543;1937, 9, 231; E. A. Andreev, Acta Physicochirn. U.R.S.S., 1937, 6, 57; M.Rivin and A. Sokolik, ibid., p. 105; P. Sadovnikov, ibid., p. 419; G. P. Kane,E. A. C. Chamberlain, and D. T. A. Townend, J., 1937, 436.44 G. von Elbe and B. Lewis, J . Amer. Chern. Soc., 1937, 59, 2025; H.Kondrateeva and V. Kondrateev, Acta Physicochim. U.R.S.S., 1937, 6,625; G.von Elbe and B. Lewis, J . Amer. Chem. Soc., 1937, 59, 656; N.Semenova, Acta Physicochim. U.R.S.S., 1937, 6, 25; A. Biron and A. Nal-bandjan, ibid., p. 43.45 Proc. Roy. Soc., 1936, A, 157, 625.46 Canadian. J . Res., 1937, 15, B, 264.47 N. R. Trenner, K. Morikawa, and H. S. Taylor, J . Chem. Physics, 1937,5, 203; K. Morikawa, W. S. Benedict, and H. S. Taylor, ibid., p. 21250 GENERAL AND PHYSICAL CHEMISTRY.minimum activation energy for the exchange between deuteriumatonis and methane is 15-6 kg.-cals.Reactions in Solution.-Reactions catalysed by acids and bases areof considerable value in the study of the various factors influencingthe rates of reactions in solution, and afford the best known andmost carefully investigated example of the relation between ratesof reaction and chemical equilibria, vix., the Brernsted equationk = G , K". Recent developments in the study of these reactionshave been summarised in papers by R. P. Bell, K. J. Pedersen,W. F. K. Wynne-Jones, and K. F. Bonhoeffer, presented a t thediscussion held by the Faraday Society.48 Particular reference mustbe made to Pedersen's, whose analysis of protofropic reactions isthe most important contribution to our understanding of thesechanges since Brsnsted first showed what is the true function of anacid or basic catalyst.The decomposition of nitroamide, which was the first reaction forwhich the Brarnsted conception was shown to be applicable,49 hasbeen re-examined by E.C. Baughan and R. P. Bell," who find thatthe Brransted relation hold6 accurately for catalytic effects of anumber of anions a t different temperatures. V. K. LaMer andJ. Greenspan 61 have studied this reaction in heavy water, in whichthe rate of the solvent-catalysed reaction is about one-fifth of thatin ordinary water : at the discussion, LaMer stated that subsequentmeasurements have shown that the rate of decomposition ofdideuteronitroamide is the same as that of nitroamide, proving thatthe two hydrogen atoms in nitroamide exchange rapidly with thoseof water.Another classical reaction, the mutarotation of glucose, has beenexamined by G. F. Smith,52 who has determined values of thecatalytic coefficients of the hydroxyl, glucosate, acetate, and otherions and also of the molecules of water, acetic, and chloroaceticacids a t different temperatures. The energies of activation areabout 17,000--18,000 cals.for all the catalysed reactions, but the'' steric factors " vary enormously and can be approximatelycalculated from the equation P = 0-36 x where K is thedissociation constant of the acid. The data also show clearly thatthe energy of activation for the water-catalysed reaction is far frombeing constant over the temperature range 0-35".Tb e depolymerisation of paraldehyde in benzene, nitrobenzene,48 Tram. GaTaday Soc., 1938, 34, 229, 237, 245, 252.4Q J. N. Br~nsted and K. J. Pedersen, 2. physikal. Chem., 1924,108, 185.50 Proc. Roy. SOC., 1937, A , 158, 464.51 Trans. Faraday SOC., 1937, 33, 1266.S2 J ., 1936, 1824; G. F. Smith and (Miss) IT. C. Smith, J., 1937, 1413WYNNE-JONES : CHEWCAL KINETICS. 51amyl acetate, and anisole has been found to be catalysed by acids,and the order of the reaction suggests that all three oxygen atomsof the paraldehyde molecule are involved.53 An attempt to studythe same reaction in the gaseous phase showed that it is pre-dominantly heterogeneous.54The interesting problem of the difference between specific effectsof hydrogen and hydroxyl ions and general acid and basic catalysis,and also the question of pre-equilibria in these reactions, have beenconsiderably clarified by experiments with heavy water. Avaluable method of investigating equilibria involving hydrogenions was proposed by P.Gross, H. Suess, and H. Steine~,~~ whoshowed that the equilibrium constant for a reaction of this typewill vary with the isotopic composition of the water according tothe equation -Bin = KO . cp + K1 . cD, where Kn is the equilibriumconstant for association with hydrogen ions in a solvent with amo1.-fraction n of deuterium oxide, KO and Kl are the correspondingconstants for pure water and deuterium oxide, and cp and CD are theeffective proton and deuteron concentrations, If the rate of areaction is governed by a similar equilibrium, we have the analogousequation for the specific rate constantsIn this way it has been possible to relate the decomposition ofdiazoacetic ester,56 the hydrolysis of a ~ e t a l , ~ ~ and the inversion ofsucrose 56 to the data for the equilibrium constants of p i ~ r i c , ~ ~and acetic acids.60 These results show that the hydrogenion is a specific catalyst for these reactions.For reactions whichrequire both an acid and a bme we may have general acid andbasic catalysis in spite of the existence of pre-equilibria between thesubstrate and hydrogen ions: an important discussion of thisproblem, based on work on the bromination of acetone and ofnitromethane as well as on the mutarotation of glucose, has beengiven by K. P. Bonhoeffer and 0. Reitz.61I n last year’s Report reference was made to a determination ofthe rate of the exchange reaction C,H,-OH + HOD = C,H,*OD +H20; if this were a slow reaction, the neutralisation of acids andbases in alcohol would be slow, which is contrary to experience;53 R.P. Bell, 0. M. Lidwell, and M. W. Vaughan-Jackson, J., 1936, 1792.54 R. P. Bell, and R. le G. Burnett, Trans. Paraday SOC., 1937, 33, 355.55 Ibid., 1936, 32, 883.58 P. Gross, H. Steiner, and F. Gauss, ibid., p. 877.67 W. J. C. Orr and J. A. V. Butler, J., 1937, 330.68 P. Gross, H. Steiner, and H. Suess, Trans. Paraday Soc., 1936, 32, 883.6% p. Gross and A. Wischin, ibid., p. 879.60 V. K. LaMer and J. P. Chittum, J. Amer. Chem. Soc., 1936,58, 1642.61 Z. physikal. Chem., 1937, A, 179, 13652 GENERAL AND PHYSICAL CHEMISTRY,it is therefore satisfactory that a repetition of the work has shownthat the reaction is too rapid to be measured.62The dissolution of metals in acids, which used to be regarded as itreaction controlled largely by the rate of diffusion of hydrogen ionsto the metal surface, was shown by M.Kilpatrick and J. H.RushtonG3 and also by J. N. Brransted and N. L. Ross Kane 64 to beeffected by acid molecules, The work of C. V. King and M. M.Braverman65 made it appear that diffusion plays an importantpart in controlling the reaction rate, but these authors were unableto formulate a mechanism which would restore the unique positionof the hydrogen ion. Additional evidence has now been obtainedof the action of molecules other than the hydrogen ion,66 but ithas also been shown that the diffusion coefficients of different acidsrun roughly parallel to the rates at which they react with metals.q7Relations similar to the Bronsted equation have been observedfor overvoltage (the Tafel equation) and for oxidation-reductionreactions (Dimroth’s relation), but a generalisation of an unexpectedtype was made by L.P. Hammett and H. L. Pfluger 68 when theyround a correlation between the rates of reaction of triethylaminewith certain esters and the dissociation constants of the acids fromwhich the esters were derived. A summary of this work is givenby Hammett,6g and other recent contributions have been madeby him and Roberts 7O and also by G. N. Burkhardt, C. Horrex, andD. I. Jenkins.71These linear relationships between the free energies of equilibriumprocesses and the allied rates have been considered by Evans andP ~ l a n y i , ~ ~ who have shown that they may be fitted into a con-sistent framework * on the basis of the general theory of reactionrates. J.A. Christiansen, in developing his theory of a chemicalreaction considered as it phenomenon of intramoleeular diff~sion,~G2 J. C. Jungers and K. F. Bonhoeffer, 2. physikal. Chem., 1936, A, 1’97, 460.G3 J . Physical Chem., 1930, 34, 2180; 1934, 38, 269.64 J . Amer. Chem. Soc., 1931, 53, 3624.66 Ibid., 1932, 54, 1744.66 M. Sclar and M. Kilpatrick, ibid., 1937, 59, 584; A. Quartaroli, AttiV Cortgr. Naz. Chim., 1936, 2, 466; M. Centnerszwer and W. Heller, J . Chirn.physique, 1937, 34, 217.6 7 C. V. King and W. H. Cathcart, J . Amer. Chem. SOC., 1937, 59, 63.6 8 Ibid., 1933, 55, 4079.70 L. P. Hammett, J . Amer. Chem. SOC., 1937, 59, 96; I. Roberts and L.P.71 J., 1936, 1649, 1654.72 Trans. Faraday SOC., 1936, 32, 1333; M. Polanyi, ibid., 1938, 34, 11;M. G. Evans, ibid., p. 49. * The criticism of the “ derivation ” of these relations is really only astatement that Evans and Polanyi have made a consistent formulation.Tram. Paraday SOC., 1938, 34, 156.Hammett, ibid., p. 1063WYNNE-JONES : CHEMICAL KINETICS. 53is led to the same type of relationship and also to the well-knowncorrelation of the frequency factor and energy of activation forrelated reactions.Polymerisation reactions are being extensively studied , and someof them are of great value because they can be examined in thegaseous phase as well as in a, number of solvents. A, Wassermann 73has given an account of the results obtained by himself and hiscollaborators for a number of reversible diene syntheses.Theassociation reactions, which both in the gas and in solution appearto be simple and bimolecular, have a '' steric factor '' of aboutin all phases; this corresponds to a small entropy of the activatedstate and is in agreement with considerations of the equilibria.Wassermann has shown that if the " steric factor " is assumed tobe the same in all phases, the collision number in a liquid is aboutten times the value in the gas,J. B. Harkness, G. B. Kistiakowsky, and W. H. Mears '* haveexamined some gaseous polymerisations and found that, although thedimerisations of cyclopentadiene, AaY-pentadiene, and py-dimethyl-hay-butadiene proceed smoothly and follow a simple kinetic course,yet styrene, vinyl acetate, and methylacetylene do not appear topolymerise.Other authors 75 claim to have measured the rates ofpolymerisation of the latter substances, but their results are ascribedby A. C. Cuthbertson, G. Gee, and E. K. Rideal 76 to catalysis byperoxides.Polymerisation and other reactions have been examined at thesurfaces of solutions by following the change in the interfacialpotential difference : the results show the marked effect oforientation of the molecules upon the course of theAn investigation which merits particular notice is the work ofJ. Steinhardt 7* on the inactivation of pepsin, a reaction which isprobably typical of protein denaturation processes. By a carefuland systematic examination of salt effects, Steinhardt was able toshow that the reaction rate is inversely proportional to the fifthpower of the hydrogen-ion concentration and that it is thereforethe pepsinate ion which reacts ; this interpretation changes theactivation energy from the apparent value of 63,500 cals.for the73 Trans. Paraday Soc., 1938, 34, 128.74 J . Chem. Physics, 1937, 5, 682.7 6 G. V. Schulz and E. Husemann, 2. physikal. Chern., 1937, B, 36, 194;7 G Nature, 1937, 140, 889.77 0. Gee and E. K. Rideal, J., 1937, 772; E. K. Rideal and J. S. Mitchell,Proc. Roy. SOC., 1937, A , 159, 206; A. E. Alexander and J. H. Schulman, ibid.,161, 115; A. E. Alexander and E. K. Rideal, ibid., 163, 70.H. Suess, K. Pilch, and H. Rudorfer, ibid., 1937, A , 179, 361.7 8 Kgl.Danske Videnskab. Selskab, 1937, 14, 1164 GENERAL AND PHYSICAL CHEZVIISTRY.reaction at constant pH to a value of 18,300 cala. for the reaction ofthe ion itself, and enables a much simpler mechanism t o beformulated.Amongst other important reactions which have been studied insolution may be mentioned the formation and decomposition ofquaternary ammonium salts,79 for which valuable equilibrium datawere also obtained; the hydrolysis of esters and the formation ofmethylpyridinium iodide in various solvents ; 80 esterification inbenzene solution ; *1 the rearrangement of N-chloroacehnilide,for which the energy of activation has been shown to vary with thetemperatureYs2 and the kinetics of which have been examined bythe use of radioactive hydrochloric acid ; g3 and the reaction betweenarsenic acid and iodine, which has been followed at equilibrium bythe exchange of radioactive arsenic.84 W.I?. K. W.-J.4. PHOTOCHEMISTRY.Since the last Report on photochemistry appeared1 a veryconsiderable amount of work on photo-reactions has been carriedout, and publications of the last few years in particular have led toa greatly increased understanding of the subject in relation to thebroader principles of general chemical kinetics. As a basis for suchinvestigation, it may be stated that the Einstein law is applied onlyto the elementary act as an absorption of light by a quantumprocess involving one quantum per absorbing molecule; the totalphotochemical yield is determined by the secondary thermalreactions of the system produced by absorption.It does notfollow that every absorbing molecule becomes activated ordissociated with a consequent primary quantum yield of unity ;internal redistribution or degradation of energy is possible, moreespecially in polyatomic molecules, while collisional deactivationmust be considered. Further advance has been made in theelucidation and comparison of all such processes in both gas-phaseand solution. Considerable progress is recorded in the fullerinvestigation of the photolysis of the simpler organic compounds,the results of which, in addition to their intrinsic interest, againyield valuable information and guidance in the examination of thefundamental processes of absorption ; in this group, carbonyl79 W.C. Davies and R. G. Cox, J . , 1937, 614.80 R. A. Fairclough and C. N. Hinshelwood, ibid., p. 538.81 M. M. Davies, Trans. Paraday SOC., 1937, 33, 331.82 J. 0. Percival and V. K. LaMer, J . Amer. Chem. SOC., 1936, 58, 2413.83 A. R. Olson, C. W. Porter, F. A. Long and R. S. Halford, ibid., p. 2467.84 J. N. Wilson and R. G. Dickinson, ibid., p. 1368.1 Ann. Reports, 1932, 29, 46RITCHIE : PHOTOCHEMISTRY. 55compounds have been subjected to further detailed investigation,and it is to them that attention is first directed.Carbonyl Compounds.4tudies in this series are of particularinterest in view of recent conclusions regarding the thermaldecomposition of organic molecules in general: e.g., L. A. K.Staveley and C. N.Hinshelwood conclude that the primary act inthe thermal decomposition of an organic molecule may involveinternal rearrangement to stable products or the production offree radicals or a combination of both these processes. Norrishand his co-workers 3* * have previously recognised the existence oftwo types of photo-decomposition, type I being predominant withshort-chain compounds and expressed byROCOR'-+ CO + (RR + RR' + R'R'),while type I1 is characteristic of long-chain compounds andinvolves the cracking of the long hydrocarbon chains in a positionC Z ~ to the absorbing carbonyl group, giving a lower carbonylcompound and an olefin. Investigation of these modes ofdecomposition has been extended to the liquid state and tosolution. Liquid acetone or acetone in benzene solution shows noreaction, but in cyclohexane some reaction occurs with thesolvent, the molecules being deactivated by collision, or removedby chemical reaction, with the solvent molecules.With di-n-propylketone in cyclohexane a t 20°, practically pure ethylene is evolved(by type I1 mechanism), whereas in the gas phase both types ofdecomposition occur; hence, in solution at room temperature thetype I mechanism of decomposition is suppressed. In a similarway, methyl ethyl and diethyl ketones show no appreciablephotolysis at 20"; but at loo", the type I mechanism is againobserved, with the important difference that radicals formed byphotolysis do not readily combine to give ethane, etc.; instead,RH is formed in an amount which is more than double theequivalent amount of evolved carbon monoxide, the general resultssuggesting that the reaction CH,*CO + CnH2%+ a = CH,*CHO +C,H,,I is possible in the solution.In the aldehydes acetaldehyde,butaldehyde, and isovaleraldehyde, on the other hand, decom-position at room temperature is the same as in the gas phase, nounsaturation in the solvent being found, and less than 2% ofhydrogen in the products; accordingly, Norrish and Bamford areof the opinion that under such conditions the type I mechanism inJ., 1937, 1668.C. H. Bamford and R. G. W. Norrish, J., 1935, 1504.E. J. Bowen and A. T. Horton, J., 1936, 1685.3 R. G. W. Norrish and (Miss) M. E. S. Appleyard, J., 1934, 874.6 R. G. W. Norrish and C. H. Bamford, Natave, 1937,140, 19556 GENERAL AND PHYSICAL CHEMISTRY.aldehydes is strikingly differentiated from that in ketones, theprimary act being represented by RCHO + hv = RH + CO.Notemperature coefficient is thus observed, in contrast to the effectwith the free-radical mechanism of the ketones. Type I1mechanism is unaffected by solution ; for instance, methyl n-butylketone decomposes in cyclohexane as in the gas phase, the productsbeing independent of temperature. The mechanism of type I isthus regarded as entirely separate from that of type 11, thisdifference indicating that such molecules may be activated in twoways.No hydrogen is obtained by illumination of acetone vapour bylight corresponding roughly to 1995-1 820 A. , the absorptionspectrum in this region consisting of discrete bands overlaid witha faint continuum.The overall reaction is expressed byCO(CH,), = C,H, + CO. The independence of quantum efficiency(y) with the energy absorbed (labs.) indicates no generation ofacetone from decomposition products, while the addition of carbondioxide and nitrogen increases the quantum efficiency and indicatesdissociation of activated acetone molecules at every collision ;ethane is less efficient. y does not appear to approach zero at lowpressure; no fluorescence was detected and if it does not exist, anactivated but stable state of the molecule must be postulated,corresponding to the idea of degradation to heateg The results arecorrelated by the use of potenfial-energy surface diagrams.Theseresults for the banded region of absorption are generally confirmedby R. Spence and W. Wild,lO who conclude that the excitedmolecule may dissociate directly into ethane and carbon monoxidewithout the intervention of radicals. On the other hand, diacetylcan be isolated from acetone illuminated at room temperature bylight of the continuous region of absorption,ll this indicatingCO(CH3), + hv = CH,*CO + CH, as the primary process. Theratio C,H,/CO is no longer unity but approaches a maximum valueof about 2.5 with increasing light intensity, one of the contributingreactions being CH, + CH,*CO = C,H, + CO. The acetyl radicalis concluded to be fairly stable at room temperature, but thestability rapidly decreases as the temperature is raised.Increaseof acetone pressure or decrease in light intensity increases theproportion of methane in the products at 60°, the reactionsuggested being CH, + CO(CH,), = CH4 + CH,*CO*CH,.7 R. 0. W. Norrish and C. H. Bamford, Nature, 1936, 138, 1016.8 J. P. Howe and W. A. Noyes, jr., J. Arner. Chem. Soc., 1936, 58, 1404.9 R. G. W. Norrish, H. G. Crone, and (Miss) 0. D. Saltmarsh, J., 1933, 1533.10 J., 1937, 352.11 See also M. Barak and D. W. G. Style, Nature, 1935,135, 307RITCHIE PHOTOCHEMISTRY. 57Various types of evidence may be adduced in general support ofthe above schemes. The quantum efficiency of decomposition ofmethyl n-butyl ketone (2480-2770 A.) is given l2 as 0.03 for type Imechanism, and 0.27 for type 11, condensation or polymerisationaccounting for 0.04.No fluorescence was detected, and since theabsorption spectrum is completely diffuse, the 65 % of moleculeslosing their excitation energy are regarded as deactivated withoutdecomposition either by internal processes or by collision. Bymetallic-mirror methods, methyl and ethyl radicals have beenisolated in the photo-dissociation of dimethyl and diethyl ketones,l3and n-propyl radicals result similarly from illumination of di-n-propyl ketone l* and from diisopropyl ketone, although in thelatter case, the isopropyl radical is first formed and immediatelytautomerises.15 The interconversion of ortho- and para-hydrogenhas been employed to show the production of the paramagneticmethyl radical from illuminated acetone and methyl iodide, but nofree radicals from propaldehyde.The polymerisation of acetyleneand ethylene photo-sensitised by acetone is regarded as due to thepresence of free radi~a1s.l~ These were not isolated fromacetaldehyde, however,18 and no free hydrogen atoms were obtainedfrom f~rmaldehyde,~~ either in the region of fine structure or inthat of predissociation, but at high temperatures the chaincharacter of the photolysis is explained in terms of free hydrogenor methyl radicals;20 when light in the banded region of thespectrum is absorbed by molecules in high vibrational levels, theprobability of transition from the excited state to an unstablestate yielding free radicals is greatly increasedl0 In acetone, thequantum measurements show that at high temperatures no chainis involved, but that chain formation occurs with acetaldehyde; 21these results have been confirmed 22 for formaldehyde, propaldehyde,and acetone, and are kinetically in agreement with the idea ofvirtually simultaneous rupture of the two bonds attaching theradicals to the carbonyl grouping.Chains in the photochemicaldecomposition of acetaldehyde . and propaldehyde at 300" are12 B. M. Bloch and R. G. W. Norrish, J., 1935, 1638.13 T. G. Pearson and R, H. Yurcell, J., 1934, 1718; 1935, 1151; N.14 T. G. Pearson and R. H. Purcell, J., 1936, 253.1 5 H. H. Glazebrook and T. G. Pearson, ibid., p. 1777.16 W. West, J. Amer. Chem. SOC., 1935, 57, 1931.17 H. S. Taylor and J. C. Jungers, Trans. Faraday SOC., 1937, 33, 1353.1 8 T.G. Pearson and R. H. Purcell, J . , 1934, 1718.19 F. Patat, 2. physilcal. Chem., 1934, B, 25, 208.20 J. A. Leermakers, J. Amer. Chem. SOC., 1934, 56, 1537.21 Idem, ibid. ; C. A. Winkler, Trans. Faraday SOC., 1935, 31, 761.22 E. I. Akeroyd and R. G. W. Norrish, J., 1936, 890.Prileshajeva and A. Terenin, Trans. Paraday SOC., 1935, 31, 148358 GENERAL AND PHYSICAL CHEMISTRY.suppressed by the addition of small amounts of nitric oxide,23 onemolecule of the latter being required for each light quantumabsorbed by acetaldehyde and one for each five absorbed bypropaldehyde. Chains are regarded as broken by the reactionbetween nitric oxide and methyl, the initial step in the mechanismbeing the production, by light absorption, of methyl and CHOradicals followed by the collision of CH, with acetaldehyde to givecarbon monoxide, methane, and methyl.F.E. Blacet and J. G. Roof 24 have shown the presence ofhydrogen in the products of photolysis of acetaldehyde, and foundthat the percentage of hydrogen increases as the quantum absorbedincreases (3130-2537 A.). This is regarded as due to the differencein kinetic energy imparted to the products of dissociation, theauthors preferring to regard the initial step as CORH + hv =R + HGO, the hydrogen being derived from the recombination ofHCO radicals, which are here not regarded as unstable.25Crotonaldehyde, contrary to expectations based on analogy withthe saturated aldehydes from a comparison of their absorptionspectra,26 shows little decomposition on illuminati~n.~~ Nofluorescence was observed even at low pressures.Although theenergy transfer without decomposition may be admitted forspectral regions where the absorption is obviously banded, theauthors 27 prefer the concept of a predominating reverse reactionwith the above-mentioned initial dissociation into R and HCO.The low quantum efficiency of decomposition of acraldehyde 28 mayalso be regarded from the internal-energy degradation point ofview. A review by G. K. Rollefson29 of work on aldehydes ingeneral and on acetaldehyde in particular indicates that suchphoto-activated molecules can react in several ways a t comparablerates, e.g., emission of radiation, production of free radicals,rearrangement to give carbon monoxide and methane, polymeris-ation; the procedure favoured is a function of the energy of theexciting wa~e-length,~O considered in relation to the molecularstructure.Hydrogen atoms but no free methyl radicals are found by the23 J.W. Mitchell and C. N. Hinshelwood, Proc. Roy. SOC., 1937, A , 159,32; 600 H. W. Thompson and J. W. Linnett, Trans. Paraday SOC., 1937, 33,874; H. W. Thompson and M. Meissner, Nature, 1937, 139, 1018.24 J . Amer. Chem. SOC., 1936, 58, 278.25 See also M. Burton, ibid., p. 1655.2 6 See also P. A. Leighton, Chem. Reviews, 1935, 17, 393.27 F. E. Blecet and J. G. Roof, J. Arner.;Chem. SOC., 1936, 58, 73.28 H. W. Thompson and J. W. Linnett, J., 1935, 1452.29 J . Physical Chem., 1937, 41, 259.30 See P. A. Leighton, L.D. Levanas, F. E. Blacet, and R. D. Rowe, J..Amer. Chem. SOC., 1937, 59, 1843RITCHIE : PHOTOCHEMISTRY. 59metallic-mirror method during the photolysis of acetic acid,sl afree-radical mechanism being postulated. No hydrogen atoms arefound in the corresponding decomposition of formic acid, photolysisbeing regarded in this case as the formation of stable molecules inone primary act.32 Acetyl peroxide33 is readily decomposed byultra-violet light, the main products being carbon dioxide, ethane,and methane; the process is a complex one, although it is perhapsnoteworthy that the ratio C,H,/CH4 in the products is highestwhen the solid itself is illuminated, and falls off rapidly for theliquid and for solutions in cycluhexane and alcohol.Absorption by Halogens.--The extinction coefficients of iodinevapour a t room temperature have been measured 34 between 4300and 6200 A,, and found to be considerably greater than previouslyaccepted values; it is pointed out that the correct mean extinctioncurves in the band region can be obtained by the addition of inertgas, such addition having no effect on the continuous part of thespectrum. The “limiting” extinction curve so obtained foriodine vapour resembles that of the extinction curve of iodinedissolved in carbon tetrachloride. Extinction coefficients areincreased by solution, especially in the cases of chlorine andbromine, while the general shape or position of the maximaremains unchanged ; the electronic transitions involved are of theintercombination type lC- ---+ 311, prohibited normally in verylight atoms, but occurring under the influence of the electric fieldsof the surrounding molecules.The decrease in extinction coefficientobserved35 in strongly illuminated solutions of iodine in carbontetrachloride and benzene is due to the dissociation of iodinemolecules into atoms, where the observed interdependence of theenergy absorbed and the iodine concentration is in agreement withtheory; recombination of iodine atoms in solution is about 1000times greater than that of bromine atoms in helium a t atmosphericpressure, in accordance with the fact that triple collisions arenecessary for recombination and that each collision is a recombiningone in solution. The quantum yield of dissociation of iodinemolecules in solution is the same in the spectral region below 5000 A.in the continuum and above 5000 A.in the band region; loss ofenergy by collisions of the second kind between activated iodinemolecules and solvent molecules does not OCCUF to any appreciableextent. The quantum yield of iodine dissociation may be unity.3t M. Burton, J. Amer. Chem. Soc., 1936, 58, 1645.32 Idem, ibid., p. 1656; see E. Gorin and H. S. Taylor, &id,, 1934, 58,33 0. J. Walker and G. L. E. Wild, J., 1937, 1132.84 E. Rabinovitsch and W. C. Wood, Trans. PaTaday Soc., 1936, 32, 540.86 Idem, ibid., p. 547.2042; A. Terenin, Acto Physicochim. U.R.S.S., 1935, 3, 18160 GENERAL AND PHYSICAL CHEMISTRY.and the average lifetime of free atoms equal to the average collisioninterval in a monatomic iodine gas; or the quantum yield may bel l n (1 due to ‘‘ primary recombination ” 36 and the lifetime of theatoms n times larger than the collision interval in the gas.Thestationary concentration of radicals in such an illuminated solutionis independent of the occurrence of primary recombination providedthat the state of the atoms or radicals formed by light absorptionis not essentially different from that of the same particles meetingaccidentally in the solution.37 This last point is also discussed byG. K. Rollefson and W. F. Libby,3* who find it necessary to assumethat the primary action of light on a molecule must be ofcomparable efficiency in solution and in the gas phase, if there is aclose correlation between the two systems.Review has also beengiven of photo-reactions in non-ideal solutions,39 and a generalcorrelation of photo-reactions in gases with those in solution .40In illuminated iodine solutions in benzene and other solvents,41 thekinetics are somewhat obscured by the reaction of iodine atomswith the solvents.In iodine vapour 42 practically every excited iodine molecule(4990-6200 A.) dissociates into atoms by collision with othermolecules, the quenching of iodine fluorescence being then due todissociation and occurring at the first kinetic collision for gasesexcept helium. The transition from the stable excited state 31TOfto the unstable repulsive state 31T0-, normally prohibited in a freeiodine molecule by the symmetries involved, is made possible bythe effect of a magnetic or non-homogeneous electric field.Sincethe transition is the more difficult the further apart the potential-energy curves of the two states, the fluorescence is less sensitive(to added gas molecules) in the red than in the green. In theiodine-sensitised decomposition of ethylene iodide in carbontetrachloride,43 light corresponding to the region of continuousabsorption is only slightly more effective in bringing aboutdissociation of iodine in the solution than light corresponding tothe discontinuous absorption; in this paper attention is also givento the intensity distribution throughout the solution. Similarly,study of the photochemical reaction of bromine atoms with finely36 J.Franck and E. Rabinovitsch, Trans. Faraday SOC., 1934, 30, 120.37 E. Rabinovitsch and W. C. Wood, ibid., 1936, 32, 1381.38 J . Chem. Physics, 1937, 5, 569.39 G. K. Rollefson, Chem. Reviews, 1935, 17, 425.40 R. G. Dickinson, ibid., p. 413.4 1 E. Rabinovitsch and W. C. Wood, Trans. Paraday SOC., 1936, 33,42 Idem, J . Chem. Physics, 1936, 4, 358.43 R. G. Dickinson and N. P. Nies, J . Amor. Chem. SOC., 1935, 57, 2382.816RITCHIE : PHOTOCHEMISTRY. 61divided platinum** leads to the conclusion that the initial step inboth yellow and blue light reactions is the same.In general, the efficiency coefficient for a process involvingcollision between an excited and an unexcited atom to form adiatomic molecule with emission of radiation is very ~ma11,~5 andthere is no doubt that the general recombination of iodine andbromine atoms requires the presence of a third body as energyacceptor and stabiliser.Absolute values for the recombination ofiodine atoms with various inert gases as third bodies have beengiven by E. Rabinovitsch and W. C. Wood; 46 calculation on theordinary basis shows, for example, that one collision in 530 is arecombining one in helium, and one in 50 in carbon dioxide, atatmospheric pressure. The recombination velocity of bromineatoms is found 47, 48 to be approximately one-third of the iodinevalues; absolute figures have also been given by K. Hilferding andW. S t e k ~ e r . ~ ~ Relative values in the case of bromine have beenestimated from the rate of hydrogen bromide photo~ynthesis,~O andfrom studies of the Budde effect; 51 in general, the efficiencies ofdifferent gases in such a stabilising process may be expressed forthese gases which act as simple energy acceptors by a commonseries CO, > 0, > N, > A > Ne > He.This seems also to applyto the formation of other complexes, e.g., H02,52 NC14,s3 theefficiency being thus higher for diatomic and polyatomic moleculesthan for monatomic ones, and increasing with growing molecularsize and the intensity of the molecular fields of the collidingparticles. The recombination of chlorine atoms does not, in general,take place by a similar mechanism; G . K. Rollefson and H.Eyring 54 have discussed the formation of Cl, from atomic andmolecular chlorine, and use has been made in other connections 55of this conception, which is considered in greater detail later.Observation in such cases is frequently complicated by surface44 J.Urmston and R. M. Badger, J. Amer. Chem. SOC., 1934, 56, 343.45 R. Rompe, Physikal. Z., 1936, 37, 807.46 J . Chern. Physics, 1936, 4, 497.4 7 E. Rabinovitsch and W. C. Wood, Trans. Faraday Soc., 1936, 32, 907.4 8 E. Rabinovitsch and H. L. Lehmann, ibid., 1935, 31, 689.49 2. physikal. Chern., 1935, B, 30, 399.50 M. Ritchie, Proc. Roy. SOC., 1934, A , 146, 828.51 W. Smith, M. Ritchie, and E. B. Ludlam, J., 1937, 1680.62 M. Ritchie, ibid., p. 867.53 J. G. A. GrBiths and R. G. W. Norrish, Trans. Faraday SOC., 1931, 27,451 ; Proc. Roy. Soc., 1934, A , 147, 140.54 J .Amer. Chem. Soc., 1932, 54, 170.55 H. C. Craggs and A. J. Allmand, J., 1936, 241; H. C. Craggs, G. V. V.Squire, and A. J. Allmand, J . , 1937, 1878; C. F. Fisk and W. A. Noyes, jr.,J . Amer. Chem. SOC., 1936, 58, 170762 GENERAL AND PHYSICAL CHEMISTRY.action. The wall of the vessel may act as third body, or removeatoms from the gas phase by adsorption; diffusion and convectionmust be adequately considered.51~ 56 Various efficiencies of atomremoval have been recorded and disc~ssed.~' The reaction ofatomic iodine with quartz has been inve~tigated.~~The triple collision has been discussed by various authors :H. Senftleben and W. Hein 59 concluded that the effective collisiondiameter in the hydrogen-atom triple collision is not essentiallygreater than the gas-kinetic diameter.E, Rabinovitsch 6o dis-tinguishes between the collision mechanisms (A' + A") + X and(A' + X) $- A", assuming that recombination takes place atcomparatively large distances between the three particles, avoidingthe idea of quasi-molecules, and considering all three partners asindependent. The number of triple collisions then depends on27&g#8 + T ~ , ~ , where T ~ , ~ , . . is the period of the collision A' + A" andT ~ . ~ that of the collision A' + X ; application to recombinationdata shows that for nitrogen, oxygen, methane, and carbon dioxideas third bodies in the recombination of hydrogen, bromine, andiodine atoms, every gas-kinetic contact leads to recombination, butwith argon the efficiency is slightly smaller, and those of hydrogenand helium are about one-tenth of that of the heavier gases.Reactions involving the Halogens.-Recent studies of thehydrogen-chlorine photocombination lend support to the view thatthe various aspects of this complicated reaction may now bepresented in one comprehensive and correlated system.Ingeneral, the kinetics may be considered in three sections : (a)oxygen-free mixtures where the rate of homogeneous gas-phasereaction is proportional to the square root of the absorbedenergy,61* 62* 63 ( b ) oxygen-rich mixtures where the rate is pro-portional to the first power of the absorbed energy, and (c) atransition region where the homogeneous gas-phase rate isproportional to a power of the energy absorbed lying between 0.5and 1, and depending on the amount of oxygen present.64 In allsections, the production of chlorine atoms by the original light66 E.Rabinovitsch and W. C. Wood, Trans. Faraday SOC., 1936, 32, 917;E. Rabinovitsch, 2. physikal. Chem., 1936, B, 33, 275.67 G. Kornfeld and S . Khodschaian, ibid., 1937, B, &j, 403; W, Steiner,Trans. Faraday SOC., 1935, 31, 962; G. M. Schwab (with H. Friess), 2.phgsikal. Chem., 1936, 178, 123.5 8 G. Brauer, ibid., 1935, 174, 435.b0 Ann. Physik, 1936, 22, 1.60 Trans. Paraday SOG., 1937, 33, 283.61 J. C. Potts and G. K. Rollefson, J . Amer. Chem. Soc., 1935, 57, 1027.62 H. C. Craggs and A. J. Allmmd, J., 1936, 241.63 Craggs, Squire, and Nlmand, Eoc. cit., ref. (55).64 R. G. W.Norrish and M. Ritchie, Prm. Roy. SOC., 1933, A, 140, 713RITCHIE : PEOTOCHEMISTRY. 63absorption is followed by the propagation of chains by the Nernstmechanism.In oxygen-free mixtures, the intensity relationship indicates thatchains are brought to an end by recombination of chain carriers.In the experiments of Craggs, Squire, and Allmand 6s an importantfraction of the chains was broken by such a, recombination processunder conditions where triple collisions could be of very infrequentoccurrence; 65 a termolecular mechanism analogous to theabove-mentioned recombination of bromine and iodine atoms ishere out of the question. Recombination of chlorine atoms mustthen take place by the reversible formation of C1, from chlorineatoms and chlorine molecules, followed by the bimolecular collisionof two GI3 molecules, the reaction between Cl, and hydrogen beingtaken as negligible in comparison with that between C1 andhydrogen.Treatment of this mechanism in the usual way leads toan expression where the quantum efficiency is proportional to thepressure of hydrogen, in agreement with the results of earlierworkers, but inversely proportional to the pressure of chlorine, aneffect not previously. observed but now confirmed.66 It is alsopossible that chlorine atoms may be removed by reaction with GI,molecules, but study of the kinetic " order '' for chlorine indicatesthat this process is insignificant a t higher pressures of chlorine,although it, may play an increasing part as the chlorine pressurefalls.At low pressures of chlorine, the rate tends to become directlyproportiond to the energy absorbed, indicating that, oxygen beingabsent, reaction cliains are broken by adsorption and recombinationof chain carriers on the walls of the reaction vessel.The relativevalues of the wall collision efficiencies for chlorine atoms and GI,molecules are then of importance, that of the latter being taken asconsiderably greater.63 If the efficiency of chlorine-atom removalis high, addition of chlorine may raise the overall reaction rate by'' poisoning " the walls; but if the chlorine-atom efficiency is low,then addition of chlorine may retard the reaction rate by facilitatingthe production of the more easily adsorbed €3,. In general, the ratio[Cl,]/[Cl] must be considered in relation to pressure of chlorine,light intensity, and the nature of the walls.Similaz effects arefound with hydrogen chloride. A retardation 67 is regarded as dueto the stabilisation of the more easily adsorbed GI3 moleeules, anacceleration as due to the poisoning of the catalysed recombination of65 See also M. Tamura, Rev. Phys. Chem. Japan, 1937, 11, 1.66 G. V. V. Squire and A. J. Allmsnd, J., 1937, 1869.67 See M. Ritchie and R. G. W. Narrish, Proc. Rog. Soc., 1933, A, 140,.112; and ref. (61)64 GENERAL AND PHYSICAL CHEMISTRY.chlorine atoms on the walls, the latter state of affairs being favouredby reactive walls and low intensity.These general results of Allmand and his co-workers arecompatible with those recorded by earlier workers.Under certainconditions 63 " abnormal " intensity and chlorine-pressure effectsare obtained and related to diffusion of chlorine atoms (e.g., fromthe light beam to the dark zones).In oxygen-rich mixtures the rate of hydrogen chloride photo-synthesis is proportional to the first power of the absorbed energy,and mutual recombination of chain carriers does not occur to anyappreciable extent. When the ratio [H,]/[CI,] is large, chains arebroken predominantly by the removal of hydrogen atoms byreaction with oxygen and a third molecule; 68i G9* 62 the quantumefficiency may then be reduced by the addition of inert gas,52 ofhydrogen chloride and of hydrogen.'O In the cases of inert gas andhydrogen chloride, the process is taken to be the stabilised formationof the HO, complex, which reacts with hydrogen to give water;the quantum efficiency of water formation thus rises with increasingpressures of hydrogen chloride, carbon dioxide, nitrogen, oxygen,and hydrogen.52 The maximum efficiency (yHzo) appears to be2.52*68~ 71, 72 Hydrogen peroxide, which can be isolated undercertain conditions from illuminated mixtures of hydrogen, chlorine,and oxygen, is rapidly destroyed by illuminated chlorine,68 theperoxide molecule being able to break two chains in the hydrogen-chlorine rea~tion.'~ When the ratio [H2]/[C12] is small, chlorineatoms may be removed by reaction with oxygen, presumably bytriple collision processes also, where KO, may be produced by thereaction between chlorine atoms, oxygen, and hydrogen chloridemolecules. 74Consumption of oxygen without inhibition of hydrogen chlorideformation has been recorded and discussed.62Craggs and Allmand 62 confirm the earlier conclusion thatphoto-combination of hydrogen and chlorine will take place inlight of 5460 A., no reaction being observed at 5790 A.At 5460 A.energy chains are improbable; the primary process in the bandedregion generally is optical dissociation to chlorine atoms, the processbeing connected with the overlying continuum. These authors68 M. Bodenstein and P. W. Schenk, 2. physikal. Chem., 1933, B, 20, 420.69 K. B. Krauskopf and G. K. Rollefson, J. Amer. Chem. SOC., 1934, 56,70 R. G. W. Norrish and M. Ritchie, Proc. Roy.SOC., 1933, A , 140, 713.7 1 K. B. Krauskopf and G. K. Rollefson, Zoc. cit., ref. (69).72 D. L. Chapman and J. S. Watkins, J., 1933, 743.78 G. Kornfeld, 2. physilcal. Chew., 1937, B, 35, 236.74 G. Kornfeld and S. Khodschaian, ibid., p. 403.327RITCHIE : PHOTOCHEMISTRY. 65oalculate that the quantum efficiency rises from 5460 to 4 9 0 0 ~ .and suggest that normal chlorine molecules with v” I: 3, whenabsorbing light of these wave-lengths, dissociate into normal atomsby means of a transition from the excited state to one of thestates In, or 3xlU; according to N. S. Bayliss 75 this assumption isnot necessary, R. G. Aickin and N. S. Bayliss 76 having shown thatthe continuous absorption in this region is due a t least partly totransitions to the 3nIu state dissociating into normal atoms.Further, if it be assumed that the reaction in this region is causedby only that part of the absorption which is continuous, thequantum yields calculated by Craggs and Allmand are increased toa value practically the same as that at wave-lengths less than4 7 8 5 ~ . These authors also report that the quantum efficiency ispractically constant in the region 47854000 A., but decreases atstill shorter wave-lengths when the chlorine pressure is low andsurface action predominant ; differences may then be attributedto the more rapid absorption of Cl,.The maximum quantumefficiency is related 75 to the region in which photo-dissociationproduces both normal and excited chlorine atoms ; a6 wave-lengthsless than 4000 A., practically only normal atoms are pr0duced.7~Recalculation of Craggs and AZlmand’s earlier results by Baylissshows that the temperature coefficient of the reaction is the sameat 5460 as a t 4360a., the energy of activation being thusindependent of wave-length.It now seems definitely established that intense drying does notretard the photo-combination of hydrogen and chlorine, thequantum efficiency of the gas-phase reaction being independentof small amounts of water v a p ~ u r .~ ~ ~ 78 Where surface action isappreciable, an adsorbed film of water is found to facilitatesomewhat the catalytic action of the walls on chlorine atoms,77with a, corresponding effect on the overall rate of hydrogen chlorideformation. These results are analogous to those found for theBudde effect in bromine,51 where the rise in pressure on illuminationis practically independent of the presence of small amounts ofwater vapour, although again there is an indication that anadsorbed film of water vapour increases slightly the surface removalof bromine atoms.Other reactions involving the halogens continue to be the object75 Tram.Paraday SOL, 1937, 33, 1339.7 7 H. C. Craggs and A. J. Allmand, J., 1937, 1889.7 8 W. H. Rodebush and W. C. Klingelhoefer, jr., J. Arne?. Chem. SOC.,1933, 55, 130; F. Bernreuther and M. Bodenstein, Sitzungsber. peuss. Akad.Wis~., 1933, 333; G. K. Rollefson and J. C. Potts, J. Amw. Chern. Soc., 1933,55, 860.Ibid., p. 1333.REP.-VOL. XXXIV. 66 GENERAL AXD PHYSICAL CHEMISTRY.of invatigation and review.79 The radical C,H,Cl, is postulated inthe photochlorination of gaseous ethylene,s0 which a t constantlight intensity proceeds a t a rate proportional to the pressure ofchlorine, but is independent of the ethylene concentration ;practically no hydrogen reacts in a mixture of hydrogen, chlorine,and ethylene, while the ethylene reaction goes to completion.The photoformations of tetrachloroethane from trans- 81 and fromcis-dichloroethylene 82 are long chain reactions, retarded by oxygenand probably involving the radical C2M2C13; of similar nature isthe formation of pentachloroethane from trichloroethylene.82 Ofchain character also is the photochemical chlorination of dichloro-benzenes 83 and the reaction of chlorine with formic a ~ i d , ~ 4 thelatter involving chloroformic acid as a probable intermediate, andsurface removal of chlorine atoms being observed under certainconditions.Chlorination of tert.-butyl chloride and related com-pounds 85 and of liquid pentane 86 has been described.Photo-brominations include those of tetrachloroethylene andchloroform,87 of acetylene 88 and other unsaturated compounds, 89and photo-iodination of the ethylenic bond has also beenin~estigated.~~~ 90 The reactions of bromine with water 91 and ofiodine with sodium formate in aqueous solution92 have beendiscussed. The velocity of combination of hydrogen and fluorinein magnesium and platinum vessels is not appreciably increased byill~mination,~~ surface removal of atoms being regarded aspredominant.Halogen Compounds.-The quantum efficiency of decompositionof iodoform and related iodides is of the order unity,e* and increases79 H.J. Schumacher, Angew. Chem., 1936, 49, 613; 1937, 50, 483; Trans.80 T. D. Stewart and B. Weidenbaum, J. Amer. Chern. Soc., 1935,57, 2036.81 K. L. Miiller and H. J. Schumacher, Z. physikal. Chem., 1937, B, 35,82 Idem, ibid., p . 455.88 C. F. Fisk and W. A. Noyes, jr., J . Amer. Chem. Soc., 1936, 58, 1707.84 (Miss) H. L. West and G. K. Rollefson, ibid., p. 2140.85 A. 0. Rogers and R. E. Nelson, ibid., p. 1027.86 T. D. Stewart and B. Weidenbaum, ibid., 1935, 57, 1702.87 J. Willard and F. Daniels, ibid., p. 2240.88 W. Franke and H. J. Schumacher, 2. phgsikal. Chem., 1936, B, 34, 181.89 A.Berthoud and M. Mosset, J. Chim. physique, 1936, 33, 272.90 G. S. Forbes and A. F. Nelson, J. Amer. Chem. SOC., 1936, 58, 182;1937,59, 693; R. E. De Right and E. 0. Wiig, ibid., 1936,58, 693.91 H. A. Pagel and W. W. Carlson, 6. Physical Chem., 1936, 40, 613.Oa N. R. Dher and P. N. Bhargava, ibid., 1935,89, 1231.*a N. Bodenstein, H. Jockusch (with S. H. Chong), t. a w g . Chem., 1937,O4 K. E. Gibson and T. Iredale, Trans. Paraday Soc., 1936, 32, 571.Electrochem. Soc., 1937, 71 (26), 297.285.231, 24RITCEUE : PHOTOCHEMISTRY. 67with the length of the carbon chain, replacement of hydrogen byhalogen, and change of the central carbon atom from primary totertiary: these effects recall the reactivity of the sodium atomwith the chlorides,95 diminishing activation energies correspondingto increased quantum yields.Other investigations reported are ofethylene i0didQ6 iodof 0rm,~7 methyl iodide, and hydrogeniodide,g8 the initial light absorption being taken to form a radicalby the breaking-off of the halogen atom. In the case of oxalylchloride,9g results are in agreement with the assumption that themolecule breaks at the C-C bond in light of short wave-length(2537 A,), but with light of 3650 A. fission at, one oE the GC1 bondspredominates.Relatively large amounts of dichlorine hexoxide are formed inthe photo-decomposition of chlorine dioxide in carbon tetrachloridesolution,l where the mechanism probably resembles that operativein the gas system.2 The decomposition of chlorine monoxide bylight of the continuous absorption region of the visible spectrum isaccelerated by the presence of hydrogen, some hydrogen chlorideand water beiig formed; the reaction between (310 and hydrogenis regarded as mainly responsible.3 The quantum yield ofdecomposition of dichlorine monoxide is approximately the same at3650 A.as in the bromine-sensitised decomposition at 5460 A.,*sensitisation by bromine molecules being favoured ; some dichlorinehexoxide is formed and is taken to be due to the bromine-sensitiseddecomposition of chlorine dioxide.2Reactions of Hydrides.-In the direct decomposition by ultra-violet light of methane, hydrogen is the main product, togetherwith acetylene, some ethane and ethylene, and other hydrocarbons :the quantum efficiency is o€ the order 1.3.5 The decomposition ofethylene is also reported.6There is little doubt that the photo-decomposition of ammonia,involves the production of NH, and H in the initial stages; final96 H.von Hartel, N. Mew, and M. Polanyi, 2. physikal. Chem., 1932, B06 R. E. De Right and E. 0. Wiig, J . Amer. Chem. SOC., 1935, 57, 2411.9 7 R. Spence and W. Wild, Proc. Leede Phil. SOC., 1936-38, 3, 141.9 8 T. Iredale and (Miss) D. Stephan, Trans. Faraday SOC., 1937, 33, 800.99 I<. B. Krauskopf and G. K. Rollefson, J . Amer. Chem. SOC., 1936,58,443.1 J . W. T. Spinks and H. Taube, ibid., 1937, 59, 1155; see also B. Luther2 J. W. T. Spinks and J. I. Porter, J. Amer. Chem. Soc., 1034, 56, 264.3 T. Iredale and T.G. Edkards, ibid., 1937, 59, 761.4 A. G. Brown and J. W. T. Spinks, Canadian. J . Res., 1937, 15, B, 213.5 P. A. Leighton and A. B. Steinsr, J . Amer. Chem. ~ o c . , 1936, 58, 1823;6 R,. D. McDonald and R. G. W. Norrish, Proc. Roy. Soar, 1936, A, 157, 480.19, 139.and R. Hoffmann, 2. physikal. Chem., 1936,177, 17.W. Groth and H. Laudenklos, Natumuiss., 1936, 24, 79668 GENERAL AND PHYSICAL CHEMISTRY.products may markedly depend on the experimental conditions,e.g., size and material of the reaction vessel, total pressure, etc. Inthe initial stages of the illumination the proportion of hydrogen inthe non-condensable products may approach loo%,' the quantumefficiency then approaching unity and indicating little regenerationof ammonia from NH, and H.Triple or wall collisions accountfor the formation of hydrogen and hydrazine. As decompositiongoes on, the proportion of hydrogen falls to 75% as given by earlierworkers: a suggested reaction is H + N,H, = NH, + NH,. Athigher pressures of non-condensable products, the quantum yieldis much less than unity, and may depend markedly on the pressureof ammonia : decreased pressure decreases the number ofefficient triple collisions, e.g., in the regeneration of ammonia fromNH, and H and y rises; on the other hand, further reduction ofpressure causes the reaction to become heterogeneous, regenerationof ammonia being taken to occur at the walls, the quantumefficiency then decreasing. Under the experimental conditions,the rate was found to be proportional to the energy absorbed.The mechanism has been further discussed el~ewhere.~The direct photo-decomposition of trideuteroammonia 10 isapproximately 1.4 times slower than that of ammonia in thepredissociation bands at 2100 A.The same kind of dependence ofy upon pressure is found to hold as for ammonia under similarconditions : the mechanisms are similar, and the differences in ratedue to slower recombination of ND, radicals (+ N, + 2D,).The quantum efficiency at 2138 A. is greater than at 2100 A., thisbeing perhaps due to direct production of nitrogen and deuteriumfrom collision of activated trideuteroammonia molecules with anormal molecule without the production of radicals. The quantumefficiency of the mercury -sensitised decomposition of ammonia a tvarious temperatures 1l is found to be approximately the same asthat for the direct reaction; once the molecule is dissociated, thesecondary reactions are the same in both cases.Earlier work12points out the errors which may arise by taking the effective meanlife of the mercury atom as a constant and neglecting thereabsorption of resonance radiation at higher mercury pressures ; 137 H. J. WeIge and A. 0. Beckman, J. Amer. Chem. SOC., 1936, 58, 2462.8 E. 0. Wiig, ibid., 1935, 5'9, 1559; 1937, 59, 827.9 W. Mund, G. Brenard, and L. Kaertkemeyer, Bull. SOC. chim. Belg., 1937,46, 211 ; W. Mund and A. van Tiggelen, ibid., pp. 104, 227.10 E. 0. Wiig, J . Amer. Chem. SOC., 1937, 59, 955.11 H. W. Melville, Proc. Roy.SOC., 1936, A, 157, 621.l2 Idem, ibid., 1935, A, 152, 325.1s See also K. Morikawa, W. S. Benedict, and H. S. Taylor, J . Ciaem.Phyaics, 1937, 6, 21669 RITCHIE PHOTOCHEMISTRY.absolute and even relative values may become ~ncertain.1~ Theapplication l2 of such correction leads to the conclusion that withammonia and the trideutero-analogue, dissociation occurs oncollision with metastable mercury (3P0) atoms, derived in turn byquenching collision from mercury (3P1) atoms. The former collisionsare equally efficient for ammonia and the deutero-compound; andthe mechanism accounts for the abnormally high inhibiting effect ofhydrogen, which is 2 0 4 0 times greater than that computed fromthe relative quenching radii of ammonia and hydrogen, andtrideuteroammonia and deuterium. The efficiency of hydrogenand deuterium atoms in inhibiting the reaction of ammonia andthe trideutero-compound is equal ; the more rapid decompositionof ammonia is then due to the more rapid removal of NH, radicalsto give hydrogen and nitrogen.Quantum efficiencies in the mercury-sensitised decompositionof phosphine and trideuterophosphine l5 may vary with thepressure; i.e., the secondary reactions are not all influenced bychange in pressure to the same degree.Calculation indicates that,in contradistinction to the case of ammonia, phosphine quenchesthe initially excited mercury atom to the ground state directly.Otherwise, the mechanism resembles that of the ammoniadecomposition ; again, direct and photo-sensitised decompositionsinvolve the same secondary reactions.The temperature coefficientof the mercury-sensitised phosphine decomposition is unity,16 as isfound with the direct decomposition. The decomposition of PH,and PD, gives P, units, appearing as a deposit of red phosphorus.17The quantum yield in the mercury-sensitised photo-decompositionof arsine is found 18 to be approximately unity, the decompositionbeing only very slightly inhibited by hydrogen. The correspondingdecomposition of silane 19 yields hydrogen and a polymerisedhydride [SiHJn(x <0.9), or a mixture of silicon and such a polymer :the radicals SiH, or SiH, probably play a part in the mechanism.Photo-sensitised exchange reactions have also been furtherinvestigated. In the mercury-sensitised exchange with deuteriumand phosphine,16 the quantum efficiency of exchange exceeds unityat higher temperatures (>500"), and indicates the chain mechanism1 4 See also N.R. Trenner, K. Morikasva, and H. S. Taylor, J . Chem. Physics,15 H. W. Melville, J. L. Bolland, and H. L. Roxburgh, Proc. Roy. Soc.,1 6 H. W. Melville and J. L. Bolland, ibid., p. 384.17 See H. W. Melville and S. C. Gray, Trans. Faraday SOC., 1936, 32, 271;18 N. L. Simmons and A. 0. Beckman, J. Amer. Chem. SOC., 1936,58, 454.10 H. J. Emel6us and K. Stewart, Trans. Faraday Soc., 1936, 32, 1577.1937, 5, 208.1937, A , 160, 406.G. Rathenau, Physsica, 1937, 4, 50370 GENERAL AND PHYSICAL CHEMISTRY.(400-500") D + PH, = PH,D + H, H + D, = HD + D. ThePD,-H, exchange proceeds similarly , both reactions being charac-terised by a high temperature coefficient.At room temperatures,the temperature coefficient is unity, and the exchange proceeds bythe recombination of the radicals produced by the mercurysensitisation : PH2 -+ D = PH,D, E€ + 1), = HD + D. Mercury-sensitised exchange reactions of hydrogen and deuterium have beeninvestigated for ammonia, methane, and water, hydrogen- ordeuterium-atom concentrations being determined by the ortho-pareconversion of the element.20 For methane 2*i 21 and ammonia,20the exchange above 300" takes place by the chain D + XH =DX + H, H + D, = HD + D : the quantum efficiency is greaterthan unity. The possible reactions in the mercury-sensitiseddecomposition of methane, deizteromethanes, and the hydrogenisotopes have been extensively discussed ; 21 at high temperatures(>300") exchange owurs by the chain process as above, but atlower temperatures exchange is mainly by recombination of themethyl radical and atomic deuterium.Deuterisation of alkylradicals in presence of atomic deuterium is a more rapid processthan that of the saturated hydrocarbons.22 Approximate energiesof activation of these reactions are discussed: the quenchingefficiency of the excited mercury atom by methane to give methyland a hydrogen atom is given a temperature coefficient correspondingto an activation energy of approximately 4.5 kg.-cals. Withwater,lfr20 reaction is slow and the exact mechanism is not socertain. The exchange efficiencies in this case are much largerthan those of the mercury-sensitised decomposition itself , and muchlarger than values calculated on the assumption that in thedeuterium-water mixtures, deuterium acts simply as quenching theexcited mercury atoms; l1 exchange does not therefore take placeappreciably by the dissociation and subsequent re-formation of thewater molecule.Photo-oxidation.-Photo-oxidations may be classified into threemain groups.23 I n the first, oxidation is due to excited oxygenmolecules or atoms, e.g., the oxidation of carbon monoxide,2*nitrogen and carbon monoxide.25 Monosilane itself is not decom-posed by light from an aluminium spark or mercury arc, but may20 A.Farkas and H. W. Melville, Proc. Roy. SOC., 1937, A , 157, 625.z1 K.Morikawa, W. S. Benedict, and H. S. Taylor, J . Chem. Physics, 1937,22 N. R. Trenner, K. Morikawa, and 33. S. Taylor, ibid., p. 203.2s H. J. Schumacher, 2. Elelitrochem., 1936, 42, 522.24 B. Popov, Acta Physicochim. U.R.S.S., 1935, 3, 223; M. SisIrin, V.26 V. Kondrateev, Acta Phyaicochim. U.R.S.S., 1935, 3, 247.5, 212.Kondrateev, and T. Suschkevitsch, J . Phys. Chern. Russia, 1936, 8, 281IuI[TCJHlX : PHOTOCHEMISTRY. 71be made to explode with oxygen under these conditions a6temperatures below the normal range for thermal igniti0n.1~Mention may also be made of the effect of altered temperature onthe photo-formation of ozone by an aluminium spark;26 inagreement with theory, [O,] = K[O2l2 at equilibrium, andcalculation gives the energy of activation of the reaction betweenoxygen atoms and ozone as 6160 & 100 cals.per mole.The second group is that where the quantum is absorbed by themolecule which is oxidised, e.g., hydrogen iodide,27 hydrogen iodideand deuterium iodide,28 involving the collision-stabilised formationof HO, and DO,, where the zero-point energies of these complexesare concluded to be of the same magnitude as those of the halidemolecules. With phosphine and trideuteroph~sphine,~~ the corre-sponding reactions involved in the chain propagation, branching,and termination at t.he walls proceed with similar velocities in thetwo cases, the positions of both lower and upper explosion limitscoincide, and the chain lengths above and below these limits arerespectively identical.In the case of methylem iodide, CH, andthe peroxidic CH202 and (CH,O), are regarded as primary products,final products being hydrogen, carbon monoxide, formaldehyde,formic acid, and ethylene glycol.30 The oxidation of gaseousformaldehyde takes place by way of formic acid, no peroxide orperacid being found; 31 with acetaldehyds the occurrence ofdiacetyl peroxide is confirmed. Both oxidations are short-chainprocesses ; in aldehydes generally peroxides may be derived fromthe radical RC0.32 Peroxidic formation has been studied 33 formethyl and other alcohols, glycerol, acetone, fructose, formic andother acids, glycol, and paracetaldehyde : in each case the activatedoxidisable molecule is supposed to form with molecular oxygen aperoxidic compound, which in turn reacts with the original activatedmolecule. In the case of r~brene,,~ the initially activated moleculeis unable to form B, stable oxygenated compound by coltision withoxygen, unless the complex is stabilised by subsequent collision orthe rubrene molecule partially deactivated to a second state where28 A.Eucken and F. Patat, 2. phyaikal. Chem., 1936, B, 33, 459.27 V. Kondrateev, E. Kondrateeve, and A. Lauris, J. Phys. Chem. Russia,28 G. A. Cook and J. R. Bates, J. Amer. Chern. Soc., 1935, 57, 1775.29 H. W. Melville, J. L. Bolland, and H. L. Roxburgh, Proc. Roy. Soc.,30 R. A. Gregory a,nd D. W. G. Style, Trans. Faradccy SOC., 1936,52, 724.31 J. E. Carruthers and R. G. W. Norrish, J., 1936, 1036.32 H.L. J. BackstrBm, 2. physikal. Chem., 1934, B, 25, 99.83 R. Cantioni, Ber., 1936, 69, 1101, 1386, 1796, 2282, 2286; Helv. Chhn.34 W. Koblitz and H. J. Schumacher, 8. ph@at. Chem., 1937, B, 35, 11.1934, 5, 1411.1937, A , 160, 417.Acta, 1936, 19, 1153; 2. wiss. Phot., 1937, 38, 90, 116, 11972 GENERAL AND PHYSICAL CHEMISTRY.8 stable complex results directly. In this group also may be citedthe reaction of mercury vapour with oxygen by light of theresonance line 2537 A., ozone formation being recorded ; 35 selectiveoxidation of mercury isotopes is claimed36 by irradiation of amercury-oxygen mixture with either the I11 or the IV componentof the 2537 line.Halogen-sensitised reactions play an important part in the thirdgroup of photo-sensitised oxidations.Radicals are formed by theaction of the halogen atom, which again form peroxide chains. Onthis basis may be considered the production of carbon dioxidefrom the monoxide, chlorine, and oxygen (radical COCl),37 and ofcarbonyl chloride from carbon tetrachloride, chlorine, and oxygen(radical CCl,) .38 Intermittent illumination of carbon monoxide-chlorine mixtures with a small oxygen content 39 indicates theformation of an active oxygen-containing intermediate, of longerlife than C1 and COCl, and able t o initiate new chains in the dark.The formation of carbonyl chloride from chloroform, chlorine, andoxygen may be almost completely suppressed by added methyl orethyl alcohol or ammonia, due to the removal of chlorine atoms,an induction period being observed .40 The chlorine-sensitisedoxidations of methane, methyl chloride, ethylene dichloride, andformaldehyde are discussed on similar lines to the above ; z3quantum efficiencies (referred to carbon monoxide formation) risefrom about 80 to 800 in the order CH, < CH3Cl < CH,Cl,, aperoxide of short life being formed from the CHCl, radical in eachcase.41 The bromine-sensitised oxidation of mandelic acid has beenfurther investigated under various ~onditions.~~ Mention mayalso be made of the mercury-sensitised oxidation of mon~silane,~~the oxidation of chloroacetic acid by potassium permanganatewith uranyl salts as photo-sen~itisers,~~ and that of various organicsubstances by hydrogen peroxide with inorganic sols as catalysts.4435 I.M. Frank, J . Phys. Chem. RussZ'a, 1934, 5, 1013; Acta Physicochim.38 K. Zuber, HeZv. Physica Acta, 1935, 8, 481 ; Chem. Zentr., 1936, 1, 494.37 M. Bodenstein, W. Brenschede, and H. J. Schumacher, Z . physikal.H. J. Schumacher and K. Wolff, ibid., 1934, B, 25, 131; A. T.as M. Bodenstein, W. Brenschede, and H. J. Schumacher, 2. physikaz.40 H. J. Schumacher and D. Sundhoff, ibid., 1936, B, 34, 300.41 W. Brenschede and H. J. Schumacher, ibid., 1936, 177, 245.42 J. C. Ghosh and S . K. Bhattacharyya, ibid., 1936, B, 31, 420; J. C.Ghosh and B. B. Roy, ibid., 1936, B, 32, 158.45 Idem, J . Indian Chem. Soc., 1936, 13, 1.44 T. Banerjee, ibid., 1937, 14, 69.U.R.S.S., 1934, 1, 833.Chm., 1935, B, 28, 81.Chapman, J . Amer.Chem. SOC., 1935, 57, 419.Chem., 1937, B, 35, 382RITCHIE : PHOTOCHEMISTRY. 73A photo-stationary state in an oxidation-reduction system isdescribed,45 and the photochemical reductions of ferric salts byorganic acids 46 and of ceric ions by water.47General.-Photolysis of tetramethyl- and tetraphenyLlead48gives metallic lead and other products which are mainly thehydrocarbons, ethane and triphenyl respectively. Use of aradioactive indicator method gave y values of the order unity forthe tetramethyl compound as vapour, though short chains,retarded by oxygen, are indicated. In solution, the value is of theorder 0.3 for both compounds, these lower values in solution beingregarded as due to deactivation or secondary recombinahion. Theformation of free radicals has been demonstrated during thephotolysis of tetramethyl-lead vapour ; the decomposition ofdimethylmercury and tetraethyl-lead, as well as of acetone, hasbeen studied similarly,49 the maximum production of radicals fromthe first being at 2200a., in the region of diffuse predissociationbands.With light of wave-length 2 5 3 7 ~ . , which is near thelong-wave limit of the overlapping continuum, the quantumefficiency of decomposition of dimethylmercury is unity at roomtemperature, but at higher temperatures rises to greater values bya chain process which is suppressed by the addition of nitricoxide.50 The primary act on light absorption is regarded as theproduction of CH, and Hg*CH,; 51 results suggest that one methylradical reacts with each molecule of nitric oxide.The absorptionspectra of polyatomic molecules containing methyl and ethylradicals have been discussed 52 and the emission spectra of freeradicals produced by photodissociation of polyatomic molecules inthe Schumann ultra-violet studied.53The quantum yield of photo-decomposition of azomethaneapproaches unity as its upper limit for initial decomposition a t lowpressures.54 Change of wave-length from 2080 to 2540 A. approx-imately halves the efficiency, indicating a decreased probability of46 G. Holst, Nature, 1937, 139, 285; 2. physikal. Chem., 1937, 179, 172.** P. La1 and P. B. Ganguly, 2. anorg. Chem., 1936, 229, 16.47 J. Weiss and D. Porret, Nature, 1937, 139, 1019.48 P. A. Leighton and R. A.Mortensen, J . Amer. Chem. SOC., 1936. 58,4% N. Prileshajeva and A. Terenin, J . Phys. Ghem. Rwsia, 1936, 8, 111.50 H. W. Thompson and J. W. Linnett, Trans. Paraday Soc., 1937, 33,51 See N. Prilesliajeva and A. Terenin, ibid., 1935, 31, 1483.62 K. W. Thompson and J. W. Linnett, PTOC. Roy. SOC., 1936, A , 156,58 H. Neujmin and A. Terenin, Acta Physicochim. U.R.S.S., 1936, 5, 465.54 G. S. Forbes, L. J. Heidt, and D. V. Sickman, J . Amer. Chem. Soc.,448.874.108; 160, 539.1935, 57, 193574 GENERAL AND PHYSICAL CEEMISTRY.dissociation before deactivation. With increasing pressure: y fallsoff rapidly, apparently due to increased collisional deactivation ;argon, nitrogen, and methane also reduce the rate of decomposition.65Detailed analysis of the products of photolysis shows that, ingeneral, the amount of nitrogen produced exceeds the amount ofhydrocarbon gas, and indicates again that the molecule does notdecompose exclusively by rupture but that it may also decomposeby a rearrangement to form stable molecules.560 ther reactions involving nitrogen compounds are : the primaryprocess in the light arrangement of o-nitrobenzaldehyde,57 thedecomposition of nitromethane and nitroethane, 58 of some aliphaticnitroso-compounds,59 of nitrates, nitrites, and nitro-compounds,Mreduction of nitrates,6i deamination of amino-acids.62In relation to the changes in chemical activity with moleoularorientation in a monolayer, the photo-decomposition of stearanilidecan be suppressed by compressing the layer so that the benzenenuclei no longer absorb in the ultra-violet region.63 Illuminationof carbon suboxide by light from a, mercury-vapour lamp leadschiefly to a polymerisation with little decomposition; 64 fromsulphur dioxide, sulphur and the trioxide may be obtainedY65 andwith nitrous oxide a t least part of the primary dissociation(1850-2300 A.) is into nitrogen molecules and oxygen atoms,66although it is not possible to state definitely that none of theprimary dissociation is into nitric oxide molecules and nitrogenatoms. Mention may be made also of reactions of thiol compoundsin solution,67 photo-dissociation of gallium halides 68 and of leadhalides,Gg action of light on zinc ~ulphide,~O lead oxides,'l and6s G.Goldfhger, Compt.rend., 1936, 282, 1502.66 M. Burton, T. W. Davis, and H. A. Taylor, J. Amer. Chem. SOC., 1937,5 7 L. Kuchler and F. Patat, 2. Elektrochem., 1936, 42, 529.68 E. Hirschlaff and R. G. W. Norrish, J., 1936, 1580.59 ,D. L1. Hammick and M. W. Lister, J., 1937, 489.60 C. H. Purkis and H. W. Thompson, Trans. Faraday SOC., 1936, 32, 1466.63 C. Weizmann, E. Bergmann, and Y. Hirshberg, J . Amer. Chem. SOC.,63 E. K. Rideal and J. S. Mitchell, Proc. Roy. SOC., 1937, A, 159, 206; see64 H. W. Thompson and N. Healey, Proc. Roy. Soc., 1936, A, 157, 331.65 M. Konstantinova-Schlesinger, J . Phys. Chem. Rzcssia, 1935, 6, 601.6 6 W. A. Noyes, jr., J . Chem. Physics, 1937, 5, 807.67 J. Weiss and H. FishgoId, Nature, 1936, 187, 71.68 A. Petrova, Acta Physicochim.U.R.S.S., 1936, 4, 559.6B B. Popov and H. Neujmin, J . Phys. Chem. Russia, 1934,5, 863.70 H. Platz and P. W. Schenk, Angew. Chem., 1936, 49, 822.7l J. Eoffmann, 2. anorg. Chem., 1936,228, 160.59, 1038, 1989.R. Cultrera, Gazxetta, 1936, 88, 440.1936, 58, 1675.J. S. Mitchell, J . Chem. Physics, 1936, 4, 725BUTLER : INTERMOLECULAR FORCES. 75white pigments.72 Measurements of photochemical yield incrystals may be made by optical and electrical means.73J. Franck and K. F. Herzfeld 74 give a theory of photosyntheticproduction of oxygen covering quantitatively many observationsdescribed in the literature, the scheme involving four photochemicalsteps and two dark reactions. Plant acids are regarded assynthesised by the same mechanism; these can be photo-oxidisedin a reaction sensitised by chlorophyll.Descriptions have been given of improved sources of continuousultra-violet radiation,75* 76 and of the 2537,77* 78 1285, and1469 A .' ~ resonance radiations. M. R.5. INTERMOLECULAR FORCES AND THE PROPERTIES OF LIQLTDS.The remarkable revival of interest in the nature and propertiesof the liquid state which has taken place in the last few years isshown by a great increase in the number of papers on this subject,which has also been reviewed in two general discussions.In September 1936 the Paraday Society held a general discussionon the Structure and Intermolecular Forces in Liquids andSolutions,l and the centenary of the birth of J. D. van der Waalswas marked by a commemoration in Amsterdam in November1937, a t which papers on the properties of dense gases and liquidswere read by many of the leading workers.2 Reference should bemade to these symposia for points of view not mentiomd here.The question of structure in liquids as revealed by X-ray diffractionis discussed elsewhere in these report^.^Intermoleculur Forces.-The general state of our knowledge of theforces between molecules, which are responsible for deviations fromthe perfect-gas law, cohesion in liquids and solids, capillarity, etc.,has been summed up by F.London in an article which provides asuitable basis for this Report. The first suggestion of the origin ofthese forces was that of W. H. KeesomY5 who presumed the genera172 C. F. Goodeve, Trans. Paraday Soc., 1937, 33, 340,74 J .Chem. Physics, 1937, 5, 237.7 5 R. H. Munch, J . Amer. Chem. SOC., 1935, 57, 1863.713 G. Jacobi, Physikal. Z., 1936, 37, 808.77 G. Kornfeld and F. Muller-Skjold, 2. physikal. Chem., 1936, B, 31, 223.'@ W. Groth, 2. Elektrochem., 1936, 42, 533.1 Trans. Paraday SOC., 1937, 33, 1.3 P. 169.1922, 23, 225.R. W. Pohl, Proc. Physical SOC., 1937, 49, Extra part, 3.H. VV. Melville, Trans. Paraday SOC., 1936, 32, 1525.Physica, 1937, 4, 915.Trans. Faraday SOC., 1937, 33, 8.Leiden Camm. Suppl., 1912, 24, 25, 26; Ph.ysiJca!. Z., 1921, 22, 12976 GENERAL AND PHYSICAL CHEMISTRY.existence of permanent dipoles in molecules. These will give risesometimes to an attractive and sometimes to a repulsive forcebetween two molecules, according to their mutual orientation, butaveraging over all possible orientations, Keesom obtained a generalorientational attraction, the mean energy of which is given bywhere p is the dipole moment and r the distance between the dipoles.that dipolar molecules would also setup induced moments in molecules in their vicinity, the magnitudeof which is proportional to their polarisability, 01.This induction$fleet also gives rise to an attractive force, the energy of which isP. Debye pointed outNeither of these effects can account for the attraction betweencompletely non-polar atoms such as the inert gases, and they alsolack the additivity which is required to account for the generalcohesion.In 1930 London showed 7 that, according to the description ofsymmetrical molecules given by wave mechanics, although averagedover a period of time the charge distribution is perfectly sym-metrical, yet a t any instant there will be various configurations ofnuclei and electrons showing instantaneous dipole moments.Thesequickly varying dipoles will act on the polarisability of othermolecules and produce in them induced dipoles, giving rise to anattractive force, having to the first a.pproximation the averageenergyU = - 2 . hvoa2/r6where vo is a frequency characteristic of the molecule.This dispersion eflect * has the characteristic of additivity, i.e., thetotal interaction between a number of molecules is the sum of theinteractions of all the pairs of molecules, and therefore is of the typerequired to account for the general cohesive or van der Waals forcesbetween molecules.The magnitude of the three effects for somesimple molecules is shown in the following table, from which it canbe seen that the inductive effect is always practically negligibleand that the orientation effect is small except with highly polarmolecules.-6 Physsikal. Z., 1920, 21, 178; 1921, 22, 302.7 2. Physik, 1930, 60, 491; 63, 245; Z. physikal. Chem., 1930, B, 11,* So called because it depends on the characteristic frequencies of the223.moleculesBUTLER : INTERMOLECULAR FORCES.Relative magnitudes of molecular interactions.p . 1Ol8. a . loz4. hv,,.co ......... 0.12 1.99 14.3HI ............ 0.38 5.4 12HBr ......... 0.78 3.58 13.3HCl .........1.03 2-63 13.7NH, ......... 1.5 2.21 16H,O ......... 1.84 1-48 18He ............ - 0.20 24.5A ............ - 1.63 15.4Xe ............ - 4.00 11.5Orient -ation Inductioneffect, effect,Q . p4/kT.* 2p2a.*0.0034 0-0570.35 1.686.2 4.0518.6 5.484 10190 10 - -- -- -77Disper-sioneffect,%a2hvo. *67.53821761059347522171.2* In erg.-cm.s xMore accurate calculations of the dispersion effect have been madeby various authors,8 and the effect of including terms of a higherorder, such as that due to the interaction of a dipole in one moleculewith a quadrupole in another, or between two quadrupoles has beenin~estigated.~ The former gives rise to an r8 term which mayamount in halide lattices to 20y, of the total interaction; but thelatter, an T-10 term, is apparently negligible.At small distances it is obvious that repulsive forces must comeinto play to prevent molecules collapsing into each other.Theseare due to the facts that : (1) at short distances the electron cloudsof two molecules no longer screen the nuclear charges completelyand the latter repel each other by their electrostatic forces; (2) theelectron clouds themselves interact and produce a repulsion. Therepulsive potential can be represented empirically by a power law ,loe.g., hr-12, but calculations by wave mechanics l1 appear to favouran exponential law R = be-rlp, where b and p are constants whichmust usually be determined empirically.12London hasshown13 that the heats of sublimation of the inert gases and anumber of simple diatomic molecules are in good agreement withthe values calculated by his dispersion formula, and an approximatecalculation of the van der Waals constant a also gave reasonableagreement.A. Muller found l4 that the formula could be success-J. C. Slater and J. G. Kirkwood, PhysicaZ Rev., 1931, 37, 686; J. G.Kirkwood, Physikal. Z., 1932, 33, 57; H. Hellmann, Acta Physicochirn.U.R.S.S., 1935, 2, 273; R. A. Buckingham, Proc. Roy. Soc., 1937, A, 160, 94,113.Various tests of these equations have been made.H. llargenau, Physical Rev., 1931, 38, 747 ; R. A. Buckingham, Zoc. cit.lo J. E. Lennard-Jones, Proc. Physical SOC., 1931, 43, 461.l1 M. Born and J. E. Mayer, 2. Physilc, 1932, 75, 1 ; F.London, Zoc. cit.l2 See J . E. Mayer, J . Cham. Physics, 1933, 1, 270, 329; W. E. Bleick andl a LOC. cit., ref. (1).J . E. Mayer, ibid., 1934, 2, 252.l4 Proc. Roy. SOC., 1936, A, 154, 62478 GENZRAL AND PHYSICAL CHEMISTRY.fully applied to the sublimation energies of the long-chain paraffins.Helium and hydrogen are, however, exceptions, because the zero-point energy in condensed phases is nearly as large as the van derWaals energy. Helium is of great interest in that the solid phaseis not stable even at absolute zero, except at pressures exceeding25 atrn0s~heres.I~ There is a transition point a t 2.19" K., at whichthe heat capacity curve has a discontinuity and the viscositydecreases by one-tenth. Calculations by F. London,lG taking thezero-point motion into account, indicate that below this temperaturethe stable liquid has a tetrahedral structure.A more direct estimate of the law of force between two moleculeshas been made by H.Kuhn and P. London,17 from the effect of thepressure of an inert gas in broadening a spectral line. In thecase of the mercury resonance line, argon produces a broadeningwhich is directly proportional to the pressure of argon and ofmercury and is therefore produced by single transits. The resultsindicate that the c r 6 law is valid between 3.4 and 4-8 xEquations of State and Partition Functions of Liquids.-Theclassical approach to the liquid state, from imperfect gases, culmin-ated in various equations of state, of which van der Waals's equationis the best known. The most useful empirical equation of thiskind is, however, that suggested by Kamerlingh Onnes and Keesom,vix.cm.PV = RT(1 + B/V + C/V2 .. .)where B, C , etc., are the first, second, etc., virial coefficients.Hitherto it has only been possible to derive the first virial coefficientfrom a given law of molecular interaction with any accuracy, andthis is only sufficient for very moderate compressions. Animportant contribution to the solution of the general problem ofdetermining all the coefficients for any law of force has been madeby J. E. Mayer,Is and the method employed has been discussed andextended by M.The introduction of the intermolecular forces into equations ofequilibrium is most conveniently made by means of the partitionfunction of R.H. Fowler and C. G. Darwin. For a perfect gas thisfunction isfg = ( 2 n d ~ T ) ~ ' ~ V b ( T ) / N h ~ . . . . (1)15 W. H. Keesom, Physica, 1934, 1, 128, 161; F. Simon, Nature, 1934, 138,16 Proc. Roy. SOC., 1936, A , 153, 576.17 H. Kuhn and F. London, Phil. Mag., 1934, 18, 983, 987; H. Kuhn,Proc. Roy. Soc., 1937, A , 158, 212, 230.18 J . Chem. Phgsics, 1937, 5, 67, 75.460, 529.Physica, 1937, 4, 1034BUTLER : INTERMOLECULAR FORCES. 79where b(T) is that part of the whole partition function which dependson the vibrational and rotational energy of the molecule.* Mayerintroduces into this function coefficients expressing the interactionin clusters of 2, 3, 4, etc., molecules. The calculation of theseCoefficients from the law of force is, however, very laborious, andit is unlikely to become an effective method for the study of gasesand liquids, at least for some t h e .A less fundamental method which avoids many of these difficultiesis to introduce the average potential field of the neighbours of agiven molecule.Thus, on the assumption that the vibrationaland rotational states are the same in the liquid as the gas, Eyring 2oexpresses the partition function of a liquid aswhere AE is the energy of vaporisation t and VIN is replaced by Vf,the free volume of the liquid. The essential part of the problem isthen the determination of the free volume of the liquid. For simplecubical packing of spherical molecules, this is S( V11'3 - whereV , is the molecular volume of the liquid and d the incompressiblediameter of the molecules, or more generally Vf = b3( V11'3 - d)3.These simple expressions are in reasonable agreement with many ofthe properties of simple liquids.Mercury is, however, an exceptionand this case has been examined in detail.21When the partition function of a liquid is completely known, theheat capacity can be calculated. If Eyring's function (2) is valid,and it is assumed that the free volume of the liquid does not varywith the temperature when the total volume is constant and thatthe rotational and vibrational terms are the same in the liquid as inthe gas, it is found that the heat capacity of the liquid at constantvolume (0,) is the same as that of the gas. This is true within& 2 cals.for many polyatomic liquids,22 except associated liquids.Thus, although these assumptions may be adequate for a broadtreatment, they fail to account for the finer features. For simpleliquids Cv follows a very uniform course between the melting pointand the critioal point.23 With monatomic liquids, such as neon,2o R. F. Newton end H. Eyrhg, Trans. Paraday SOC., 1937, 33, 73;21 J. F. Kencaid and H. Eyring, J. Chem. Physics, 1937, 5, 687 ; see also22 LOC. cit., ref. (20).23 E. Bauer, M. Magat, and M. Surdin, J. Phys. Radium, 1936, 7, 441.* The Helmholtz maximum work function is A = KT logf per molecule, andt More correctly, AE a t 0' K. should be used.H. Eyring and J. Hirschfelder, J. Physical Chem., 1937, 41, 249.ref.(40).the pressure is obtained as (dA/du)F = -p80 GENERAL AND PHYSICAL CHEMISTRY.argon, mercury, and czesium, C, has near the melting point thevalue 3R = 6 cals., which is characteristic of the solid state. Asthe temperature rises, the value falls and approaches 2R = 4 cals.at the critical point. L. Brillouin 24 has suggested that the twodegrees of freedom of transverse vibrations in the solid become a,rotational motion in the liquid, which makes a contribution R(instead of 2R) to C,. The higher values a t lower temperaturesare ascribed to some sort of quasi-crystallinity. E. Bartholomi5 andA. EuckenZ5 are able to account for the large values of C,, byassuming a particular shape for the potential field of a molecule inthe liquid, but to explain the full decrease they are obliged toassume an association between molecules which decreases withrising temperature.J. D. Bernal 26 ascribes the high values of C,near the melting point to the energy required to bring about thenecessary changes in the equilibrium configuration of the liquid.The theory has not, however, been developed far enough fornumerical calculations. Liquid hydrogen and helium have muchlower Cv’s, rising with temperature, because a t these low tempera-tures the classical equipartition has not beenJ. E. Lennard-Jones and A. F. Devonshire 28 start from the samebasis as Eyring, but they go further and evaluate the potential fieldproduced by the neighbours of a given molecule from the knowninteraction constants. A molecule in a dense gas is regarded asconfined for most of its time in a cell or box, the walls of which arecomposed of its nearest neighbours. When this box is large, thepotential inside is fairly uniform except near the boundary, wherethere is a region of low potential.As the density of the gas increasesand the size of the box diminishes, the boundary fields begin tooverlap and the potential in the middle of the box falls, reachinga minimum and rising again a t high compressions when therepulsive forces become important. By using constants in theequation +(r) = Am - Br-m, derived from the deviations fromthe perfect-gas law at low densities, the potential of a molecule inthe box can thus be expressed as a function of the volume of theform x(v) = uIvv - p/vp.When this is inserted in place of AEin (2), a partition function is obtained which is capable ofreproducing the critical phenomenon? and the critical temperaturesof hydrogen, neon, nitrogen, and argon calculated from it are ingood agreement with the observed values.24 J . Phys. Radium, 1936, 7, 153; Trans. Paraday Soc., 1937, 33, 54.=5 Ibid., p. 45.27 E. Bartholorn6 and A. Eucken, 2. Elektrochem., 1936, 42, 547.28 Proc. Roy. SOC., 1937, A , 163, 63; also J. E. Lennard-Jones, Physica,26 Ibid., p. 27.1937, 4, 941BUTLER : INTERMOLECULAR FORCES. 81The entropy of vaporisation of a liquid according to (1) and (2)is approximatelyIt has long been known that AX = L/T is nearly constant for normalliquids at their boiling point (Trouton's rule).J. H. Hildebrand 29found that a better constancy was obtained when liquids are com-pared at temperatures at which they give rise to equal vapourconcentrations. Under this condition Vs is constant and (3) thenimplies that the free space in the liquid is also constant. Eyring 3Ohas pointed out that, since the energy required to make a hole ina liquid is the same as that required to remove a molecule from theliquid, the concentration of holes in the liquid must be equal to theconcentration of molecules in the vapour. At equal vapourconcentrations liquids will therefore have equal " concentrationsof holes "; in conjunction with (3) this gives a simple explanationof Trouton's rule.* When the molecular rotations are not fullydeveloped in the liquid, as in associated liquids in which directedbonds exist, the entropy of vaporisation will be greater than (3),as is found to be the case.It is evident that in the theory of liquids, so far as it has beendeveloped, the free space is of the first importance and is the maindistinction between a solid and a liquid.The existence of free spacein the liquid permits the diffusion of molecules and the movementsnecessary for viscous flow. The concept of holes of molecular sizealone is, however, much too simple. No doubt holes of all sizesexist, and the distribution of such sizes has been considered byW. Altar.31The Viscosity of Liquids.-An exponential relation between theviscosity and temperature was apparently first suggested by J.deGuzmBn Carran~io,~~ wiz., r ) = AeBIRT. Although many variantsof this equation have been suggested,33 e.g., Andrade's equation,34q = A/vl'3 . ec'wT, which frequently gives somewhat better agree-ment with the measurements, the simplicity of the original equationAB=Rlog(V,/Vj) . . . . ' (3)29 J . Amer. Chem. SOC., 1915, 37, 970.30 J . Chem. Phyaiw, 1936, 4, 283; see also 0. I(. Rice, ibid., 1937,5, 353.31 Ibid., p. 577.33 For bibliography, see A. G. Ward, Trans. Paraday SOC., 1937, 33, 88.34 Phil. Mag., 1934, 7, 17, 698.* If V , is the volume of 1 mol. of vapour, the concentration of holes in theliquid is equal to the concentration of molecules in the vapour, i.e., NIT',,where N = Avogadro's number. The free space in 1 mol.of liquid is therefore7, = (N/ V,)v,,,V,,,, where v, is the volume of the molecule and V, the rnoIe-cular volume of the liquid. Thus V,/V, is approximately V,Z/V,*. Thevalue of this for benzene a t its b. p. is 8.9 X lo4, which gives Ah'= 22.8 cds.per degree, in quite good agreement with the Trouton's law constant.32 Anal. Pis. Quim., 1913, 11, 35382 GENERAL AND PHYs1CA.L CREMISTRY.makes it more suitable as a starting point of theories of viscosity.Recent discussions have been mainly concerned with the natureof B, which can be regarded as the activation energy of the viscosityprocess. Guzm&n showed that in some cases there is a roughcorrespondence between B and the latent heat of fusion. A. G .Ward,35 discussing viscosity from the point of view of 9.D. Bernal'stheory 36 of the configuration of liquids, suggests that such a relationis to be expected when the liquid is merely a disordered version ofthe solid, but when the configuration in the liquid is essentiallydifferent, B and L will not be connected.H. Eyring has discussed the theory of viscosity in a series ofpapers.57 The theory has developed progressively and all theideas brought forward are not easily summarised, but broadly twomechanisms are considered : (1) A " unimolecular " mechanism inwhich each molecule moves independently ; this movement can onlytake place if a hole of suitable size is wailable and the activationenergy is the energy required to make the hole. (2) A " bimole-cular " process in which two molecules in adjacent layers, in relativemotion, rotate round each other through 90".The free spacenecessary for a movement of this kind is considerably smaller thanfor the first. Since the energy required to make a hole of molecularsize is equal to the energy of vaporisation, the activation energyof the viscosity process should be related to the energy ofvaporisation.Some very interesting facts emerge from the comparison of thesequantities. Liquids fall into well-defined groups. For carbontetrachloride, benzene, cydohexane, methane, argon, nitrogen, andcarbon monoxide, which have presumably practically sphericallysymmetrical fields of force, the ratio ( AE)vap./(AE)dsc. is 2-3-24, butfor unsyrnmetrical molecules such as pentane, chloroform, ethyliodide, carbon disulphide, and diethyl ether the ratio is 3-5-4.0.These ratios fit in with the bimolecular hypothesis. The metalshave much larger ratios, varying from 8 to 30, and the interestingsuggestion is made that while the unit for vaporisation is theatom, the unit of flow is the much smaller metal ion.If thedifference of size of the atom and ion is allowed for by using theratio (AEvap./AEvisc,) (riOn l ~ a t o m ) ~ , normal values of 2 4 are obtained.The normal hydrocarbons all have ratios of ca. 4, which suggeststhat the chains are curled up in the liquid state,With water, the ratio decreases as the temperature rises, i.e.,AEd, decreases more rapidly than AEv,.. Eyring suggests that36 LOC. cit., ref. (33).s7 J. Chem. Physics, 1936, 4, 283; R.H. Ewell and H. Erying, &bid., 1937,36 Trans. Farday Soc., 1937, 33, 27.5, 726; R. H. Ewell, ibid., p. 571BUTLER : INTERMOLECULAR FORCES. 83when there are directed forces, such as hydrogen bonds, the activ-ation energy of the viscosity process will consist of the usual fraction(ca. l/4) of that part of the energy of vaporisation which is due toundirected attractive forces, but all the energy of directed bondswhich must be broken in the process of flow. The rapid decrease ofAE~s, is then due to the decrease in the number of hydrogenbonds with rising temperature. The high visoosity of glycerol,sugar solutions, etc., is due to the preponderence of this structuralactivation energy.MeEting.-One of the most diEcult points to understand aboutliquids is the existence of a sharp melting point.If a liquid differsfrom a solid merely in a greater degree of thermal agitation anddisorder, it is not clear why the process of melting is so sharp.The nature of melting has been considered by a number of authors.J. Frerike13* has argued that the crystalline and the liquid state,like the gaseous and the liquid state, are separated by a continuousseries of states of increasing disorder, the intermediate stages,however, being unstable. This idea has also been supported byF. Simon,39 who suggests that, since the properties of the liquidand the crystalline state of a substance approach each other at highpressures, in the limit a critical point may be reached. J. D. Bernal,however, regards the liquid state as characterised by a fundamentalirregularity, so that the difference between solid and liquid is one ofkind rather than degree.At the melting point the free energy of the solid and liquid arethe same, and the greater energy of the liquid is therefore com-pensated by a greater entropy.One factor in this is the communaluse of the free volume of the liquid by all its rn0lecules.~0 In thesolid each molecule can be regarded as confined to a region in theneighbourhood of the lattice point, but in the liquid it is reasonableto suppose that the free volume is shared by all the molecules.This gives rise to a term R in the entropy of the liquid, and thus,when the rotational and vibrational terms are the same in the solidas in the liquid, the entropy of fusion may be expected to be 2 units.This is approximately the case with metals, but with most othersubstances rotation does not occur in the solid, and the entropy offusion is greater on account of changes of the rotations andvibrations.With many organic compounds, the entropy of fusionis about l2,41 and when a much smaller value than this is found,8 8 Trans. Paraday Sac., 1937, 33, 58; Acta Physicochim. U.R.S.S., 1935,39 Trans. Paraday Soc., 1937, 33, 65.40 J. Hirschfelder, D. Stevenson, and H. Eyring, J. Chem. Physics, 1937,4 1 P. WaIden, 2. Elektrachem., 1908, 14, 713.3, 633, 913; Bull. Awd. Sci. U.R.S.S., 1936, 371.6, 89684 GENERAL AND PHYSICAL CHEMISTRY.it is indicated that rotational degrees of freedom already exist inthe solid below the melting point.The appearance of such rotations in solids has now been observedin a considerable number of cases.42 Usually there is not a sharptransition, marked by a latent heat, when the molecules begin torotate, but this occurs gradually over a range of temperature inwhich the heat capacity rises to a maximum and falls again andanomalous dielectric constants are often observed.The theory ofthis transition has been worked out by R. H. Fowler.43Miscelbneous Relations.-E. Bauer, M. Magat, and &I. Surdin 44have found that many of the properties of a large variety of liquidsfall OE identical curves when plotted against a reduced temperature,8 = (7’ - Tf)/(Tc - Tf). This function varies from 0 a t thefreezing point (T,) to 1 at the critical point (TJ, but except at lowtemperatures it is not very sensitive to Tf, and M.Surdin45 has sinceshown that in many cases the van der Waals reduced temperatureT/Tc is equally effective. The effect of temperature on normalliquids at least is thus remarkably uniform, and it is clear that asingle model of the liquid state may be expected to apply to allnormal liquids.R. H. Fowler 46 has considered the surface tension of liquids in theneighbourhood of the critical point, and derived the relationQ = const. x (1 - T/Tc)2 for this region. Since van der Waals’sor Dieterici’s equations of state give (1 - Tc/T) K (dii,. - dVapJ2,it follows that o = K(dli,, - dvaPj4. This is Macleod’s equation?the basis of Sugden’s parachor, P = MK1/4, which has hithertobeen quite empirical.The derivation cannot, however, be extendedto lower temperatures at which Macleod’s relation still holds. Theabsolute calculation of the parachor by similar methods gavepromising results.Dielectric Properties of Polar Liquids.Dielectric Constants.-When an electric field is applied to a vapourof dipolar molecules a certain amount of orientation in the directionof the field is produced, and according to P. Debye’s well-knowncalculation the average value of the orientational polarisation permol. is related to the dipole moment p byPo = (4x/3)Np2/3kT . . . . * (1)42 For review, see C . P . Smyth, Chem. Reviews, 1936, 19, 329.43 Proc. Roy. SOC., 1935, A , 149, 1; A , 151, 1; cf.0. K. Rice, J. Chem.44 J. Phys. Radium, 1936, 7, 441 ; Trans. Paraday SOC., 1937, 33, 81.45 J. Phys. Radium, 1937, 8, 294.4 6 Proc. Roy. Soc., 1937, A, 159, 227.Physics, 1937, 5, 492 ; T. S. Chang, Proc. Camb. Phil. Soc., 1937, 33, 524BUTLER : INTERMOLECULAR FORCES. 85The total molecular polarisation is related to the dielectric constantE by the Clausius-Mosotti formula,where (4x/3)Nao is the non-orientational part of the polarisation.If the dipolar molecules were quite free to rotate in liquids, thesame orientational polarisation should be produced in solution innon-polar solvents or in the pure liquid. Actually, it is well knownthat the polarisation in the pure liquid is much smaller than that inthe vapour, or in dilute solutions in non-polar solvents; e.g., fornitrobenzene in dilute carbon tetrachloride solution a t 20", Po =369 c.c., whereas in the pure liquid Po = 95 C.C.When the molarfraction of the dipole molecules is increased from 0 to 1, two kindsof polarisation curves are encountered : (1) the polarisation of thedipolar constituent falls continuously, (2) it passes through amaximum (e.g., alcohols in non-polar solvents). This behaviourhas hitherto been ascribed to the formation of groups of two ormore molecules, the dipole moment of which may be greater orless than that of the single dipoles, according to their disposition,but no clear quantitative treatment of this conception has beenp~ssible.~'P. Debye has now extended 48 his theory of orientational polaris-ation to include the possibility of coupling of dipoles.If it besupposed that the rotation of the molecule may be hindered by apotential field which can be represented by - E cos 8 , where 8is the angle between the axis of the dipole and an axis in which themolecule is held a t any instant by the fields of neighbouringmolecules, the orientational polarisation is found to bewhere L(p) is Langevin's function of p = E[kT. When B > kT,the factor [l - L2(p)], by which the polarisation is reduced by thecoupling energy, is 2kTIE. The values of EIkT required to accountfor the polarisations in pure water and nitrobenzene are 11 and 10.It is also shown that when E is large, dielectric saturation occurs atmuch larger field strengths than is to be expected from the simpletheory, which is in accordance with experimental results.In solutions E might be expected to be a function of the con-centration of dipoles, and F.H. Muller has discussed49 the nature4 7 See C. P. Smyth, " Dielectric Constant and Molecular Structure,'' 1931,48 Physikal. Z . , 1935, 36, 100, 193; Chem. Rewiews, 1936, 19, 171.49 Physikal. Z., 1937, 38, 498.Chap. IX86 GENERAL AND PHYSICAL CHEMISTRY.of this function, comparing Debye's formula with A. E. van Arkeland J. L. Snoek's formula 50which accounts for the variation of Po with concentration over avery wide range.51 When the degree of coupling is great (cnv2 >3kT; n is the number of dipoles per c.c., and c a constant), thisbecomes Po = (4x/3)N(l /cn), and hence a comparison with Debye'sformula suggests that E = 2cnp2/3.As an explanation of thisrelation, Miiller suggests that the internal field acting on a dipole ina dielectric liquid is F = Cnp, and the Debye coupling energy, whichis the interaction of a given dipole with this field is E = @' =Cnp2. The constant C is almost the same for a wide variety ofmolecules (excluding hydroxy-compounds) and is independent ofT to near the critical temperature. In dilute solutions, where thecoupling energy is small, this does not, of course, apply, and altern-ative expressions are given.This theory gives a continuous fall in the polarisation as theconcentration of dipoles is increased, and gives no explanation of themaximum in the polarisation-concentration curves which occurswith alcohols, which are also anomalous in that the pure liquidshave dielectric constants that decrease with rising temperat~re.5~The anomalous behaviour is no doubt connected with the specialcharacteristics of hydrogen bonds.W. D. Kumler has shown 53that the orientational part of the dielectric constant, when correctedso that it applies to equal numbers of molecules, is a linear functionof the dipole moment in many liquids, but when hydrogen bond8are present the value is considerably greater.In a very important paper, L. Onsager 54 has discussed liquids ofhigh dielectric constant from a radically novel standpoint. Histreatment agrees with Debye's original value of the orientationalpolarisation, but rejects the Clausius-Mosotti formula (2) connectingthe polarisation with the dielectric constant.In the latter theinternal field is represented by F = E + 4x1, where E is theexternally applied field, and I the electric moment per unit volume.In Onsager's treatment the field which acts on a molecule in apolarised dielectric is divided into a cavity field G, proportional toE,' and a reaction field R, which is proportional to the total electricmoment and depends on the instantaneous orientation of themolecule. In Mosotti's formula it is assumed that the total internal80, 707.Physikal. Z., 1932, 33, 662; 1934, 35, 187; Trans. Paraday SOC., 1934,61 See Ann. Reports, 1936, 33, 132.52 Cf. P. Girard, Tram. Puraday SOC., 1934, 30, 763.ss J.Amer. Chem. Soc., 1935, 57, 600. 64 Ibid., 1936, 58, 1486BUTLER : INTERMOLECULAX FORCES. 87field is effective in orientating the molecule, but according foOnsager, R can never exert a torque on the molecule and theorientating couple is produced entirely by Q. The reaction field Rcauses an enhancement of the dipole moment of the molecule andalso increases the moment induced by R. Hence the dipole momentis a function of the dielectric constant of the medium. As the resultthe polarisation is represented by(E - r2)(2c - r2)/c(r2 + 2)2 = 4ni~p,2/9kTwhere r is the refractive index; or, when E is large,2&/(r2 + 2)2 - 41tN. p,-,2/9kT . . . . (5)J. Wyman 55 had found that the Clausius-Mosotti formula failedt o give an adequate interpretation of the polarisation of liquids andsolutions of high dielectric constant.In aqueous and alcoholicsolutions of amino-acids, the dielectric constant increases linearlywith the concentration (n); dzldn, is practically independent of thesolvent and is closely correlated with the relative dipole momentsof the solute molecules, so that in these solutions the dielectricconstant appears to be an additive property of the moments present.These facts find no simple interpretation on the Mosotti formula,and Wyrnan therefore suggested that for large values of E, thedielectric constant is a linear function of the polarisation. He hassince shown 56 that in many pure liquids the dielectric constant i srelated to the polarisation, calculated from the dipole moment byDebye's formula, by P = ( E + l)/q where x varies from 6 to 10 andis usually close to 8.5.Onsager's expression (5) gives this valuewhen r = 1-46.Dispersion of the Dielectric Constant .-When the frequency ofelectric oscillations is increased, a point is eventually reached atwhich the molecular rotations of the dipolar molecules can no longerkeep pace with the applied field, and the dielectric constant thenfalls from its low-frequency value E, to that produced by theelectronic part of its polarisation alone, E ~ . In Debye's theory ofthe effect, the orientational polarisation for the frequency v is givenby the complex quantityP o = T ' - 4xN p2 1.3!cT * 1 + 2XiVT 'where T is the relaxation time. Fkom the real part of this, thedielectric constant is obtained asE = EO + (Em- E0)/(1 + V2/VS2)J .Amer. Chem. SOC., 1934, 56, 636; Chem. Review, 1936, 19, 213,J . Amer. Chem. Soc., 1936, 58, 1482$8 GENERAL AND PHYSICAL CHEMISTRY.where v, is the critical frequency at which E is half-way betweenthe two limits E, and E ~ , and is related to 7 byvs = 1/2X+O + 2)/(E,+ 2)Connected with this are two other effects, which are more con-veniently measured : (1) a high-frequency conductivity whichincreases as E decreases, (2) a dielectric loss or absorption of energyin the diele~tric,~' which shows itself in an easily measured heatingeffect, This is negligible in non-polar liquids, and in dilute solutionsis proportional to the number of dipolar molecules ; it is a maximumat the frequency vs* and at considerably lower frequencies isproportional to v ~ .~ ~On the assumption that the frictional resistance to rotation of thedipoles may be represented by Stokes's law, Debye calculates therelaxation time as T = 4~ya,~/kT, where 3 is the viscosity of theliquid and a the radius of the dipolar molecule. The relaxationtimes obtained by either of the above methods are of the order of10-11 sec., and for dilute solutions in non-polar solvents are in quitegood qualitative agreement with the calculated values. 59 Quantit-atively there are discrepancies ; e.g., W. Holzmiiller has investig-ated solutions of a series of ketones and finds a progressive increasein z with the size of the molecule, but the molecular radii requiredare about half the actual values, and the ratio of the relaxationtimes in hexane and benzene is not constant and is usually smallerthan the ratio of the viscosities.Recent observations by L. D'Orand J. Henrion suggest that the relaxation time may apply tothe rotation of parts of the molecule, for z for pdi(chloromethy1)-benzene, which has rotating dipoles, is considerably less than thatfor o-dichlorobenzene.In pure liquids there are considerable discrepancies, particularlywith hydroxylic compounds, which have been extensively investig-ated with wave-lengths between 1 and 100 cm.G2 P. Girard andP. Abadie G3 found that in a series of polyhydric alcohols, a decreasesF. Harms, Ann. Physik, 1901, 5, 564; J. Malsch, Physikal. Z., 1932, 33,19; 1936, 37, 849; Ann.Physik, 1932, 12, 865; 1934, 20, 33; M. Wien,Physikal. Z., 1936, 37, 155.68 P. Debye, Trans. Paraday SOG., 1934,30,679 ; Physikal. Z., 1934,35, 102.69 G. Martin, ibid., 1936, 37, 164, 665.6o Ibid., 1937, 38, 574.Ibid., p. 635; Compt. rend., 1936, 202, 398.e2 M. von Ardenne, 0. Gross, and G. Otterbein, Ph,ysikal. Z., 1936,37,533 ;M. Wien, ibid., p. 869; J. Malsch and E. Keutner, ibid., 1936, 36, 288; C.Schreck, ibid., 1936, 37, 157, 549; C. Schmelzer, ibid., p. 162; Ann. Physik,1937, 28, 35; A. Esau and G. Boz, Physikal. Z., 1937, 38, 774; G. Hettner,ibid., p. 771 ; D. Elle, Ann. Physik, 1937, 30, 354.6s J . Phys. Radium, 1935,6, 296; 1936,7,211; Compt. rend., 1936,202,308BUTLER : MTERMOLECTJLAR FORCES. 89as the number of hydroxyl groups is increased, and with glycerol,complex curves are obtained indicating more than one relaxationtime. In solutions of these compounds, T is a maximum at thesame concentration as the maximum of the polarisation.The discrepancies from the simple theory might be due to thenot unlikely incorrectness of Stokes's law when applied to rotations.Debye has attempted to improve the theory by taking account ofhindrance of dipole rotation by the potential field of surroundingmolecules (p.85), and finds that when the coupling energy E ismuch greater than kT, (6) is replaced by4xN ,p2 1 P o = - -3 ' 3kT 0*5p( 1 + 2xiu~/O*5p)The meaning of this is that P, is divided by the factor p/2 as before(P = EJkT), and the effective relaxation time is obtained bydividing T by the same factor, i.e., T' = ~/0-5p.It is too early to judge the success of this development. Againstit are observations of W.Hackel,65 who has determined the relax-ation times of the lower alcohols over a range of temperature andfinds that for each alcohol the experimental value 7' is a linearfunction of T and at certain temperatures T i / 7 is greater than 1.Hydrogew Bonds in Associated Liquids.-The association ofmolecules in liquids through the formation of hydrogen bonds hasbeen discussed in a prcvious Report 66 and it is only necessary toreview recent developments. The whole subject is covered by alengthy article by M. L. Huggins.67 J. D. Bernal and H. D.Megaw 68 suggested that two kinds of bonds should be distinguished,for which they proposed the names, hydrogen and hydroxyl bonds,severally.In the former, the hydrogen atom is attached with equalfirmness to both oxygens, i.e., -0----33----0-, the energy of thebond is about 8000 cals./mol., and the distance between the oxygens2-5-4.65 A. In the latter, the hydrogen remains unsymmetricallyattached to one of the oxygens, i.e., -0----H-0-, giving a bondenergy of ca. 5000 cals./mol. and an oxygen distance of 2.7-2.9 A .Since it is admitted-that probably an almost continuous series ofcases between these extremes exists, the necessity of the distinctionhas not been everywhere accepted.@ The nature of the hydrogen64 Physikal. Z., 1935,36, 100, 193; P. Debye and W. Ramm, Ann. Physik,1937, 28, 28.65 Physikal.Z., 1937, 38, 195; W. Hackel and M. Wien, ibicl., p. 767;cf. E. Keutner and G. Potakempo, ibid., p. 635.6g Ann. Reports, 1934, 31, 37.6 7 J . Org. Chem., 1936, 1, 407; cf. E. N. Lassettre, Chem. Reeriews, 1937,g8 Proc. Roy. Soc., 1935, A , 151, 384.139 See, e.g., W. H. Rodebush, Chem. Review8, 1936, 19, 69.20, 25990 GENERAL AND PHYSICAL CHEMISTRY.bond has also been discussed by A. Sherman and R. H. Gillette,'Owho suggest that since its exact nature is a t present unknown, it isbest defined by the thermochemical binding energy.Hydrogen atoms attached to oxygen give rise to well-markedabsorption bands in the near infra-red, which are usually easilydistinguished from the bands due to CH, and, being characteristicallyinfluenced by changes of the binding energy, they promise to givemuch information about the nature of the hydrogen bonds, and havebeen the subject of a large number of investigations.E.Ganz 71has observed the effect of changes of temperature and the additionof salts for a wide range of wave-lengths. The two bands at 0.77 pand 0.85 p, for example, sharpen considerably as the temperature israised from 12" to go", and in concentrated salt solutions theabsorption resembles that in pure water a t a higher temperature,ie., the salts raise the " structural temperature " of water, the effectbeing greater the larger the anion. The bands at 3 p, 4.7 p, and 6 phave also been studied,72 and the effects of temperature on themaxima are recorded. J. R. Collins and C.Moran 73 have alsostudied the effect of salts on the infra-red bands of water, andfind that small ions, such as those of lithium and magnesium,decrease, while large ions increase, the structural temperature, whichagrees with J. D. Bernal and R. H. Fowler's conclusions as to theeffect of these salts on the temperature of maximum density.74G. Bosschieter and J. Errera 75 studied dilute solutions of water incarbon disulphide and carbon tetrachloride and found bands between3500 and 3700 cm.-l, which they attribute to the valency vibrationsof the single molecule. In liquid water and in more concentratedsolutions in various solvents 76 another band appears a t 3300 cm.-l,which arises from interactions between the molecules.The Raman spectrum of liquid water has been examined byM.Magat 77 and J. H. Hibben,T8 who interpret the low-frequencyshifts in terms of the Bernal-Fowler model. I. R. Rao and P.K0teswaram,7~ however, suggest that some of the lines on whichthese investigators rely are excited by weak secondary lines of theThe situation with water itself is not very clear.70 J . Arner. Chem. Soc., 1936, 58, 1135; J . Physical Chem., 1937,41, 117.2. physikal. Chem., 1936, B, 33, 163; Ann. Physik, 1936, 26, 331; E.Ganz and W. Gerlach, Physikal. Z., 1936,37, 358.72 E. Ganz, Ann. Physik, 1937, 28, 445.73 Physical Rev., 1936, 49, 869; 1937, 52, 88; cf. J. R. Collins, ibid., 1925,74 J. Chem. Physics, 1933, 1, 515.76 J . Phys. Radium, 1937, 8, 229.7 7 Ann. Physique, 1936, 6, 108; Tram.Paraday SOC., 1937, 38, 114.7 8 J . Chern. Physics, 1937, 5, 166.26, 771.76 Compt. rend., 1937, 204, 1719.70 Ibid., p. 677BUTLER : INTERMOLECULAR FORCES. 91mercury arc. P. C. Gross, J. Burnham, and P. A. LeightonS0have made a more elaborate study, and conclude that water israther more than 2-co-ordinated between 25" and go", while in icea t O", 4-co-ordination predominates.The first systematic study of the infra-red spectra of hydroxy-and amino-compounds was that of 0. R. Wulf and U. Liddel,81who, working with a glass spectrograph, examined the absorptionat about 1-5 p ( k e . , the first overtone of the fundamental band) ofmany of these compounds in dilute solution. They found aremarkable constancy of wave-length and intensity, except incompounds containing intramolecular bonds, where this bandappeared to be completely absent.(Recent investigation suggeststhat it has probably shifted to wave-lengths beyond the regionexamined.) Certain o-substituted groups in phenol cause a splittingof the band into two, ascribed by L. Pauling 82 to the possibility ofcis-trans-isomerism.Many hydroxyl compounds have, besides the sharp fundamentalband at cn. 2.75 p, another much wider band near 3 p. P. Molletand J. Errera s3 showed that in the case of ethyl alcohol the latteris due to association and disappears on dilution of the alcohol with anon-polar solvent, while the former becomes more pronounced.Similar observations were made by R. Freymarqs4 who found thatthe former band is strong in the vapour, but weak in the liquid a troom temperature, and is intensified by dilution and by raising thetemperature, while the latter predominates in the solid and liquid atlow temperatures.Similar observations have been made by A. M.Buswell, V. Dietz, and W. H. Rodebu~h.~~ J. J. Fox and A. E.Martins6 have made a careful examination of the absorption inthis region of phenol and various aliphatic and aromatic alcohols.The wave-length of the sharp band varies slightly in the differentcompounds. With phenol the intensity of the longer-wave" association band " is proportional to the number of moleculesnot contributing to the short-wave band, and it is possible todetermine the numbers of single and associated molecules. Theassociation band is complex, and its maximum moves to shorterwave-lengths as its intensity falls.The results suggest that,particularly with the aliphatic alcohols, the complex molecule may80 J. Amer. Chem. SOC., 1937, 59, 1134.81 Iblbid., 1933, 55, 3574; 1935, 57, 1464; 0. R. Wulf, U. Liddel, and S. B.82 Ibid., p. 94.8s Compt. rend., 1937, 204, 259; Trans. Furaday SOC., 1937, 33, 120.84 Compt. rend., 1937, 204, 261, 1063 ; Bull. SOC. chim., 1937, 4, 944.8 5 J. Chem. Physics, 1937, 5, 501.8 6 Proc. Roy. SOC., 1937, A , 162, 419.Hendricks, ibid., 1936, 58, 228792 QENERAL AND PHYSICAL CREMISTRY.contain more than two single molecules, in agreement with thethermoohemical results of K. L. Wolf .8'have made very similar observ-ations on the second harmonic at about 1 p.In the first place theystudied acetic acid in the vapour state and found that the intensityof the sharp band at 0.97 p was proportional to the concentration ofsingle molecules. In solutions of alcohols they found 89 two broadbands, one on each side of the narrow hydroxyl band, whichincreased in intensity as the concentration increased. Thefrequencies of the primary bands of various molecules are shiftedin the liquid state or in solutions by amounts which are proportionalto the interaction energy of the hydroxyl group with the surroundingatoms. A. Naherniac 90 has also made an extensive study of theshifts of these bands in passage from the vapour to the liquid stateand finds a correlation between the shifts and the magnitude of thevan der Waals forces.It is evident that the infra-red spectra promise to provide a verypowerful method of investigating the interactions of hydroxyl andsimilar groups with each other and with other molecules in pureliquids and solutions, but so far the work has been exploratory andthe precise origin of the broad secondary bands has not yet beenelucidated.Other investigations, which cannot be described indetail, are listed bel~w.~lR. M. Badger and S. H. BauerJ. A. V. B.6. ELECTROCHEMISTRY.Thermal Data for E.M.F. Measurements.--It has been indicated inprevious Eeports 1 that the study of heats of dilution and of otherthermal properties of solutions of strong electrolytes has attractedinterest in recent years. In view of the difficulties connected withprecise calorimetric measurements, especially with dilute solutions,it is important to record the development of methods based ondeterminations of the E.M.F.'s of reversible cells.The E.M.F. ofsuch a cell is a measure of the free-energy change in the process taking87 Trans. lraraday SOC., 1937, 33, 179; 2. physilcal. Chem., 1935, B, 28, 1.88 J . Chem. Physics, 1937, 5, 369, 605.s1 E. L. Kinsey and J. W. Ellis, J . Chem. Physics, 1937, 5, 399; P. Bar-chiewitz, Compt. rend., 1937, 204, 1184; s. Mizushima, Y. Uehara, and Y.Morino, Bull. Chem. SOC. Japan, 1937,12, 132 ; D. Williams and E. K. Plyker,J. Chem. Physics, 1936, 4, 460; J . Opt. SOC. Amer., 1936, 26, 149; M. V.Volkenstein, Acta Physicochim. U.R.S.S., 1936, 4, 357; W.Gordy et al.,J . Amer. Chem. Soc., 1937, 59, 464; Physical Rev., 1936, 50, 1151; 1937,51, 564; J . Cham. Physics, 1935, 3, 664; 1936, 4, 749; 1937, 5, 284; J .Physical Chem., 1937, 41, 645.89 Ibid., p. 399.Ann. Physique, 1937, 7, 528.Ann. Reports, 1932, 29, 29; 1934, 31, 58GLASSTONE : ELECTROCHEMISTRY. 93place therein, and by means of the Gibbs-Helmholtz equation it ispossible to calculate the decrease in heat content for the sameprocess. This method, as applied to “ chemical cells,” has been inuse for several years for the determination of the heat changesassociated with chemical reactions, and the results have been recog-nised as more accurate than those obtained by direct thermo-chemioal measurement .2 It should be possible, theoretically, byapplying an analogous method to ‘‘ concentration cells ” to acquireinformation related to heats of dilution, but it is only in the pastfew years that the technique of the study of these cells has attainedthe standard necessary for the measurements to be of value. Theappropriate thermodynamic equations have been known for sometime and various attempts were made to apply them, but the moderndevelopments may be considered as having originated four yearsago.It is probably not yet true to say that the results obtainedfrom concentration cells are more accurate than those derivedfrom the best calorimetric studies, but the former procedure has theadvantage of being simpler and more rapid.Consider a concentration cell without transport, ie., one in whichtwo solutions of the same electrolyte at different concentrations,c and c’, are separated by a suitable electrode reversible with respectto one of the ions of the electrolyte ; for the passage of x faradays ofelectricity, where x is the valency of the other ion, the quantityof electrolyte in the more concentrated solution ( c ) is decreased by1 mol., whereas that in the other (c’) is increased by the same amount.At constant pressure the change in heat content of the first solutionis equal to the partial molar heat content * of the solute (R2) at theconcentration c, whereas for the second solution ( c ‘ ) the correspond-ing change is Hz’.The free-energy change is represented by xP . AE,where AE, the E.N.F. of the concentration cell, is generally expressedas E - E’; this corresponds to the fact that in cells of the typeunder discussion it is the practice to measure the E.M.F.’s of thetwo halves separately.By the Gibbs-Helmholtz equation itfollows thatH2 - B2’ = zP[(E - E’) - T(6(E - E’)/W>] . . (1)and hence if E and E’ are measured at a number of tem-peratures, so that the temperature coefficient at constant pressure,i.e., 6(E - E’)/6T, is known, the change in heat content can bedetermined.From the thermodynamic standpoint the important quantity is2 Cf. H. S. Taylor and G. St. J. Perrott, J . Amer. Chem. SOC., 1921, 43, 45.* This is defined as the heat change on the addition of 1 mol. of solute to aninfinitely large amount of solution, i.e., 6H/6n, the pressure being constant94 GENERAL AND PHYSICAL CHEMISTRY.gz - g2, i.e., the value when one of the solutions is infinitelydilute : this is known as the relative partial molar heat content, z2,and represents the change of heat content relative to an idealsolution.Two methods have, in general, been used to determineL, from the experimental quantity R2 - H i . First, the E.M.F.’sfor a series of different concentrations are extrapolated to give Eo.Graphical extrapolation to zero concentration. is at present insuffi-ciently accurate for the purpose and the following procedure hasbeen adopted. The E.M.F. of the half-cell containing the solutionc may be represented by the equationE = EO + (vRT/xP) log, cf . . . . . (2)where Eo is the E.M.F. of the cell when c is zero, f is the meanactivity coefficient of the ions a t the concentration c, and v is thenumber of ions produced by one molecule of electrolyte.Theactivity coefficient can then be expressed in terms of the concen-tration by means of an extension of the Debye-Huckel equation,e.g., that of Gronwall, LaMer, and Sandved, and by using theE.M.P.’s for a number of cells with different concentrations of solutethe best value for Eo may be found.3 The substitution of Eo forE’ in equation (1) then gives the corresponding value of B2 - R2O.Instead of using the actual E.M.P. of the cell ( E ) for purposes ofcalculation it has been proposed to replace it by a quantity E,,where E is equal to E, - (vRT/xE’) log, c ; substituting this for Ein equation (1) and replacing E’ by EO, it is readily seen that theequation becomesRz - B,o = Lz = zE’[(Ec - EO) - T{S(Ec - EO)/ST>] .(3)so that z, is obtained directly.4 In order to evaluate the temper-ature coefficient the E.M.P.’s are expressed as a function of thetemperature, e.g., E = a + bt + ct2 + . . ., where t is the Centi-grade temperature, and then differentiated, giving b $- 2ct + . . .The second method involves the determination of the relativepa.rtia1 molar heat content of any convenient solution, say c’,i.e., H,‘ - H: is determined; hence by adding this value to thatof H , - H i , obtained from equation (l), the quantity E, for thesolution c is obtained. The relative partial molar free energy P - %Oof the solute in a solution is, by definition,F - Fi-J = (VRT) logef + (vR17) log, cwhere the symbols have the same significance as before; from this,See I.A. Couprthwaite and V. K. LaMer, J . Amer. Chem. Soc., 1931, 53,4333.4 V. K. LaMer and I. A. Cowperthwaite, ibid., 1933, 65, 1004GLASSTONE : ELEOTROCHEMISTRY. 95by direct application of the Gibbs-Helmholtz equation, it followthatBy means of an extended form of the Debye-Huckel equation,e.g., the form usually known as the Huckel equationY5 it is possibleto express logJ in terms of the concentration : then by usingequation (4) an expression for z2 may be obtained involving concen-trations, the temperature coefficient of the dielectric constant of thesolvent, and other quantities which are either universal constants ormay be calculated from the experimental E.M.F.data. By meansof the resulting equation, a,l - &O may be evaluated for theconcentration c’, and so L2 for other concentrations may be obtained.In order that the results should be as little dependent as possibleon the method used for determining z2’ - B20, it is evident thatthe reference solution c’ should be as dilute as possible; concen-trations as low as 0.001 molal have been used. For a range of nottoo concentrated solutions, for which the Huckel equation applies,the z2 values for the whole series may be calculated by means of theequation relating z2 to the concentration : the results obtained inthis way are in good agreement with those given by the othermethod6 This is, of course, to be expected provided the adjustableconstants in the Huckel equation have been correctly chosen.The familiar Kirchhoff equation states that AC, = 8(AH)/8TY andapplied t o the case under discussion this leads toH - = E2 = - v ~ T 2 ( 6 logef/sT) .. . . (4)where Zp2 is the partial molar heat mpacity of the solute * in the givensolution and is the corresponding value at infinite dilution; thedifference is called the relative partial molar heat capacity, and thismay be obtained from the temperature coefficient of z2 at constantpressure. If z2, obtained as described above, is expressed as afunction of temperature, then 6z2/6T is readily obtained by dif-ferentiation. It will be observed from equations (1) and (2) thatthe determination of z2 involves differentiation of the E.M.F.withrespect to temperature; hence zap - zi9 is dependent on the seconddifferential and a high order of accuracy is not to be expected unlessthe E.M.F. measurements are very exact. Nevertheless, wheredirect calorimetric studies have been made the results are generallyin satisfactory agreement with those obtained from E.M.F. data.6- 76 E. Hiiukel, Physikal. Z., 1925, 26, 93.* H. 8. Harned and R. W. Ehlers, J . Amer. Chem. Soc., 1933, 55, 2179.7 H. S. Harned and J. C. Hecker, ibid., p. 4838; H. S. Marned and M. A.* This is defked as the change in heat capacity of a large amount of solutionCook, ibid., 1937, 59, 496, 1290.on addition of 1 mol. of solute96 GENERAL AND PHYSIUAL CHEMISTRY.The methods described above for the determination of thermaldata from measurements on reversible cells have been applied tothe study of solutions of hydrochloric acid in water and in methylalcohol-water mixtures 8 ~ 6 ; sodium and potassium hydroxides ; '* *cadmium,10 thallium,ll b&rium,l2 and potassium 13 chlorides ;sodium,14 zinc 39 15 and cadmium 16 sulphates ; sulphuric acid ; 1'hydrobromic acid in water and in lithium chloride solutions; l8and sodium bromide.19Thermal Properties and CmLcentration.-According to the limitingDebye-Huckel equation, applicable to very dilute solutions, thelogarithm of the activity coefficient (f) is a linear function of dz;it - follows, - therefore, from equations (4) and (5) that both z2 andcpa - cgp should also vary in a linear manner with 6 .2 0 It isdoubtful whether the limiting slopes obtained by the electrochemicalprocedure for very dilute solutions have any significance, since someform of the Debye-Huckel equation is always used for the purpose ofextrapolation to infinite dilution. Until an independent method ofextrapolation is used, therefore, the data are only of theoreticalvalue in connexion with the study of relatively concentrated solu-tions. The thermal data obtained from E.M.P. measurements forsuch solutions, like those obtained calorimetrically, show a linearvariation with dz, although the concentrations are too high for thelimiting equation to be applicable; the slopes of the lines are,however, not in agreement with those to be expected at high dilu-tions, and each electrolyte shows individual behaviour.An attempthas been made to determine whether this individuality could beeliminated by expressing thermal properties a t constant volumeinstead of at constant pressure, thus avoiding any disturbing effectsthat might arise from the thermal expansibility and the compressi-bility of the solution; the results show that these factors are not* H. S. Harned and H. C. Thomas, J. Amer. Chem. SOC., 1936, 58, 761 ;G. Wkerlof and J. W. Teare, ibid., 1937, 59, 1855.9 H. S. Harned and M. A. Cook, ibid., p. 496.lo H. S. Harned and (Miss) M. E. Fitzgerald, ibid., 1936, 68, 2624.l1 I. A. Cowperthwaite, V. K. LaMer, and J. Barksdale, ibid., 1934, 56, 54.l2 E. A. Tippetts and R.F. Newton, ibid., 1934, 56, 1676.la H. S. Harned and M. A. Cook, ibid., 1937, 59, 1290.lo H. S. Harned and J. C. Hecker, ibid., 1934, 56, 650.l6 H. S. Harned, ibid., 1937, 59, 360.l6 V. K. LaMer and W. G. Parks, ibid., 1933, 55, 4343; V. I(. LaMer andE. L. Carpenter, J. Physical Chem., 1936, 40, 287.17 I. A. Cowperthwaite and J. Shrawder, J. Amer. Chem. BOG., 1934, 56,2345; H. S. Harned and W. J. Hmer, ibid., 1935, 57, 27.l8 H. S. Harned, A. S. Keston, and J. G. Donelson, ibid., 1936, 58, 989;H. S. Harned and J. G. Donelson, ibid., 1937, 59, 1280.lo H. S. Harned and C. C. Crawford, ibid., p. 1903.2o Anw. Reports, 1934, 31, 59GLASSTONE : ELECTROCHEMISTRY. 97responsible for the specific properties of differentIt appeared possible that the square-root relationship, at least asapplied to concentrated solutions, might have little theoreticalsignificance, as the non-electrolytes urea and mannitol were reportedto show a similar variation of thermal properties with concentration.22It must be pointed out, however, that the measurements extendedover a relatively small range, the heat capacities varying by onlysmall amounts, so that the conclusions cannot be regarded as estab-lished. In fact, measurements with sucrose show that the apparentmolar heat capacity is more nearly a linear function of the first powerof c than of 2/23 whereas for urea, over a considerable concentrationrange, neither relationship is appli~able.~*Since the last report on the subject,2* relatively little calorimetricwork has been done on the thermal properties of dilute solutions ofelectrolytes; some accurate measurements have been made of theintegral heat of dilution * of sodium chloride solution^,^^ and of theheat capacities of sodium and barium chloride solutions.26 Thesequantities can be related to one another and also to the relativepartial molar heat contents and heat capacities discussed above?’The Debye-Huckel limiting law is undoubtedly applicable in verydilute solutions, and the slope of the line showing the variation ofthe integral heat of dilution with the square root of the concen-tration is in better agreement with the requirements of this law 28than was a t first r e a l i ~ e d .~ ~ The difficulties lie, not only in themeasurements, but also in the extrapolation of the results obtained.Theory of Concentrated Solutions of Electrolytes.-The problem ofdilute solutions of strong electrolytes can be regarded, a t least forthe present, as solved, and consequently attention is being turnedto the theory of more concentrated solutions and of mixtures, Itappears that in both these connexions the ((principle of specificionic interaction,” originally postulated by J.N. Brmsted in 1922 2921 F. T. Gucker and T. R. Rubin, J . Amer. Chern. SOC., 1936,67, 78.22 C. M. White, ibid., 1936, 58, 1620.23 F. T. Gucker and F. D. Ayres, ibid., 1937, 59, 447.26 E. A. Gulbransen and A. L, Robinson, ibid., 1934,56,2637.26 T. F. Young and J. S. Machin, ibid., 1936, 58, 2254; C.M. White, ibid.,27 See M. Randall and F. D. Rossini, ibid., 1929,51, 323.28 T. F. Young and W. L. Groenier, ibid., 1936, 58, 187.20 See Ann. Reports 1933, 30, 24.* The integral heat of dilution per mol. of solute is the heat change ondiluting a solution containing 1 mol. of solute at a given concentration toinfinite dilution; it is related to z2 by the expression Ljmz2. dm, where WI isIdem, ibid., p. 2962.p. 1615.m athe molality of the solution.REP.-VOL. XXXIIV. 98 GENERLL BND PHYSICAL CHEMISTRY.and subsequently developed more explicitly,30 is likely to play animportant part. According to this principle the interaction betweenions of the same sign is determined entirely by electrostatic (“ long-range ”) forces, since as a result of their mutual repulsion they spendrelatively little time in close proximity, but for ions of opposite signspecific (“ short-range ”) forces, dependent on the nature of theiom, also make themselves felt.The original Debye-Huckeltreatment considered only the electrostatic forces between ions of afinite size in a medium of dielectric constant equal to that of thesolvent; later, Huckel applied a correction for the effect of theions on the dielectric constant, regarded in the nature of a ‘‘ salting-out ” effect, which was of importance for relatively concentratedsolutions. To make the picture more complete, however, it isnecessary to add a term for the interaction between ions andundissociated molecules, equivalent to the salting-out of non-electro-lytes, and a term for molecule-molecule interaction, representingthe departure of solutions of non-electrolytes from ideal behaviour.The exact trwtment is too complicated to be carried further atpresent, but it can be simplified by introducing the principle ofspecific ionic interaction: it is assumed that as far as the short-range forces are concerned only ions of opposite sign need be con-sidered, In this way G.Scatchard31 has obtained an expressionfor the “non-ideal” free energy, and using the simple thermo-dynamic relationship between this and the activity and osmoticcoefficients,* he obtained for these quantities expressions the firstterm of which corresponds to the Debye-Huckel equation. Thezeis, however, an important difference : it has been argued that thequantity K which appears in the Debye theory, and represents thesquare of the reciprocal of the thickness of the ionic atmosphere,should be proportional to the number of ions in unit volume ofsolvent, rather than of solution.This means that the quantityZcx2, where c is the volume concentration, should be replaced byXmz2, where m is the molality, i.e., mols. per 1000 g. of solvent, atconstant temperature and pressure. In order to test Scatchard’sequations, there are only two quantities which are not known withsufficient accuracy and must be obtained empirically from measure-ments on two solutions : these are (a) the volume occupied by theions in solution, and (b) the coefficient for molecule-molecule inter-action.The former is found to be 3.15 times the actual volume, as80 E, A. Guggenheim, PhiE. Mag., 1935,19, 586; 1936, 22, 322.81 Chern. Reviews, 1936,19, 309.* The osmotic coefficient is obtained by dividing by actual osmotic effect,e.g., depression of the freezing point, by the value for an ideal solution,allowance being made for ionisation assumed to be completeGLASSTONE : ELECTROCHERIISTRY. 99compared with four times to be expected from the van der Waalstheory, and the latter is one-third the value for an aliphatic hydro-carbon in water. By using these data, the calculated values for t h eosmotic coefficient have been compared with those observed for the15 alkali chlorides, bromides, and iodides at concentrations up toand generally exceeding 4 ~ .The agreement, although not perfect,a t least shows that the new development is a step in the right direc-tion, It i s of interest to record that numerous valuable experimentaldata concerning osmotic and activity coefficients, covering a consider-able range of have recently become available as aresult of an improvement in the " isopiestic '' method of determiningvapour pressures of solutions 33 first attempted, without greatsuccess, by W. R. Bousfield in 1917.Mixtures of Electrolytes.-The application of the theory outlinedabove to mixtures of electrolytes is a matter of difKculty, butprogress has been made by means of a simplified treatment. Startingfrom a general equation, based on statistical considerations, of thefree energy of a quantity of fiuid containing a number of com-ponents, an equation has been deduced3* which, for the osmoticcoefficient (+) of a particular ion in a mixture of electrolytes, can bewritten in the form4 - 1 = + Bm + Cm1'5 + Dm2 + + .. . . (6)where m is related to the total ionic concentration of the solutionand A is the appropriate Debye-Hiickel constant, and representsthe interaction between the ion and its atmosphere. The quantitiesBy C, D, E , ete., depend on the various forces in the solution and onthe respective ionic concentrations ; B is the equivalent of the short-range interaction between a pair of ions, C is that for the pair ofions and their ionic atmospheres, D for three ions, E for three ionsand their atmospheres, and so on.It has been found experi-mentally35 that B and C are linear functions of the ionic concen-trations, whereas D and E axe quadratic functions. These relation-ships are exactly those derivable from the principle of specificinteraction which would make B and C , for two ions of the samesign, and D and E, for three ions of the same sign, so small as to benegligible. In the original application of the principle Brmnstedconsidered an equation equivalent to the A and B terms only of32 R. A. Robinson et cd., J . Amer. Chem. Soc., 1934,50,1839; 1935, b7, 116133 D. A. Sinelair, J , Physical Chem., 1933, 87, 395.34 G. Scatchard and S. 8. Prentb, J . Amer. Chem. SOC., 1934,66,1486,2314.85 Idem, ibid., p. 2320; me abo B. B. Owen and T. F. Cooke, ibid., 1937,gQ,1165; 1936, 58, 959; 1937,59, 84.2273, 2277100 GENERAL AND PHYSICAL CHEMISTRY.equation (6) ; hence the modern development represents the exten-sion of the concept to the coefficients of higher powers of the concen-tration of the solution, which take further inter-ionic forces intoconsideration. It may be mentioned that a similar relationshipfor B and D, although not quite as simple for C and E, applies inconnexion with the activity coefficient of an ion in a mixture ofelectrolytes.A simpler treatment of concentrated solutions and of mixedelectrolytes, which appears, however, to be less promising, has beendeveloped by G.Akerlof : for two different strong electrolytes of thesame valency type a t the same concentration and with equal ap-parent mean ionic diameters, the Huckel equation gives the relation-ship for the two activity coefficients logfi/’f2 = Ec, where c is theconcentration.This has led to the formulation of the empiricalrule logy - log yR = Elm, where is the activity coefficicnt, interms of molality, of any electrolyte and yR is the value for a referencesubstance at the same molality m, and El is a constant for the formerelectrolyte. Activity data for a number of substances appear to bein good agreement with this rule36 for relatively concentratedsolutions. In further development of the argument, it was postu-lated that in a series of solutions of two electrolytes, at constant ionicstrength, the logarithm of the activity coefficient of either is a linearfunction of its concentration, and is independent of the total con-centration, Combining these rules with the fact that the activityof any solute must be constant in its saturated solutions, a t a definitetemperature, equations have been deduced whereby the compositionsof saturated solutions of two 36 or more 37 soluble strong electrolytescan be calculated, provided certain activity data are available. Theprocedure can also be reversed, and the activity coefficients of hydro-chloric acid a t high concentrations have been determined frommeasurements of the solubility of sodium chloride in these acidsolutions.38The postulates described above have, however, been subjected tosome criticism : the results of activity-coefficient measurements bythe freezing-point method show that the first rule is certainly notcorrect in solutions more dilute than l ~ ., although at higher concen-trations it may be a satisfactory approximati~n.~~ The rule mayalso be tested by means of calorimetric measurements ; by combiningAkerlof’s equation with equation (4), it can be shown that ananalogous expression L2 - Lz(R) = k2m should apply : this has beena e G. Akerlof and H. C. Thomas, J. Amer. Chem SOC., 1934, 56, 593.3 7 G. Akerlof, {bid., p. 1439; G. Akerl6f and 0. Short, ibid., 1937, 59, 1912.38 G. Akerlof andH. E. Turek, ibid., 1934, 56, 1876.39 G. Scatchard and S. S. Prentiss, Zoc. cit., ref. (36)GLASSTONE : ELECTROCHEMISTRY. 101found to be only approximately true, there being marked deviationsin dilute solutions.40The extensive work of H.S. Harned and others, on activity co-efficients in mixtures of halogen acids and their salts, shows that theresults may be expressed by the equationsandlogyl = aim, + logy10 . . . . . (7)log y2 = a2m2 + log yZ0 . . . . . (8)where y, and y2 are the activity coefficients of acid and salt, respec-tively, in the mixture; ylo is the value for the acid a t zero concen-tration in the salt solution, and yZ0 that for the salt at zero concen-tration in the acid; ml and m2 are the molalities of acid and saltrespectively, the sum of which is constant and equal to the ionicstrength. It can be shown that according to Akerlijf’s rules a1 anda2 should be constant and independent of the total concentration :this is not the case in dilute solution, although the values appear tobecome more constant a t higher con~entrations.~1 The rules can,therefore, only be regarded as approximate, but they may proveuseful in the study of concentrated solutions.Harned41 has shown that the application of the principle ofspecific ionic interaction in its simple form requires al and a2 inequations (7) and (8) to be equal numerically but of opposite sign,i.e., al + or2 = 0.The actual sum appears to tend towards zero invery dilute solutions, but appreciable deviations occur at higherconcentrations : it is possible that Scatchard’s extension of theBrransted principle, described above, to higher powers of the con-centration may remove the discrepancy.Dissociation Constants.-The potentiometric method in commonuse for the determination of the dissociation constants of acids andbases involves the measurement of the hydrogen-electrode potentialin mixtures of the acid, or base, and its salt, a calomel electrode beingused as standard. These measurements not only involve the un-certainty of a liquid junction, but in addition there is a divergenceof opinion concerning the potential of the calomel electrode on thenormal hydrogen scale.Both these difficulties have been avoidedin a method for the determination of the thermodynamic dissociationconstants of weak acids developed by H. S. Harned and his colla-b o r a t o r ~ . ~ ~ For an acid HA a cell without liquid junction of thetypeAglAgCl ( s ) NaCl (m3) NaA (mz) HA (m1)lH2 (1 atm.)is set up, where m,, m2, and m3 are the concentrations of acid, its40 A.L. Robinson and H. S. Frank, J. Amer. Chem. Soc., 1934,56, 2312.4 1 H. S. Harned, ibid., 1935, 5’9, 1865.42 H. 8. Harned and R. W. Ehlers, ibid., 1932, 54, 1350102 GENERAL AND PHYSICAL CHEMISTRY.salt and sodium chloride, respectively.cell is given bywhere the a terms represent the activities of the ions indicated in thesubscripts, and E, is the E.N.P. of the cell consisting of AgIAgCland the hydrogen electrode, H, (1 atni.), in a solution containinghydrochloric acid having a mean activity of unity. This is known,from measurements on cells with the acid at different concentrationsand appropriate extrapolation to infinite dilution, with an error ofless than 0.1 mv.The thermodynamic dissociation constant ( K )of the acid is equal to &.uA,/aEA, and making use of the fact thatthe activity (a;) may be replaced by the product of the activitycoefficient (y) and the molality (m), it can be readily shown thatequation (9) can be mitten in the formThe E.M.F. (E) of thisE = E, - (RT/P)log,a,.a,,, . . . . (9)and henceThe right-hand side of this equation may be put equal to - (RT/P)log K‘, where K’ becomes identical with K a t infinite dilution,for then the various activity coefficients are unity and the corre-sponding term is zero. Since E, is known and E can be measured,the left-hand side of the equation can be evaluated for various con-centrations of acid, salt, and sodium chloride; the value of m,,,may be put equal to m3 in dilute solution, mHA is given by m, -[H’], and mAt by m2 + [H’], a sufficiently accurate value of [H’],the hydrogen-ion concentration, being obtained from an approximatevalue of the dissociation constant.If the resulting quantities,which are equal to - (RT/P) log, K’, are plotted against the ionicstrength of the mixture in the cell and extrapolated to zero concen-tration, the intercept gives - (RT/P) loge K , from which the thermo-dynamic constant K may be obtained. Alternatively K‘ itself,obtained by multiplying the value of the left-hand side by PIRTand taking antilogarithms, may be plotted against the ionic strength,whence the intercept for infinite dilution gives K directly. Thisprocedure involves more calculations, but the extrapolation ispresumably more accurate.The general method has been used todetermine the dissociation constants of the following acids : aceticin water and in methyl alcohol-water and dioxan-water,43 pro-43 H. s. Warned and R. w. Ehlers, J. Amer. Ghern. Xoc., 1933, 55, 652;H. S. Harned and N. D. Embree, ibid., 1935, 57, 1669; H. S. Harned andG. L. Kazanjian, ibid., 1936,68, 1912GLASSTONE : ELECTROCHEMISTRY. 103p i o n i ~ , ~ ~ chlor~acetic,~~ sulphuric (second formic,Q7 boric,48b u t y r i ~ , ~ ~ phosphoric (first and second stages),m carbonic (bothstages),5f lactic,52 and glycollic.53 A corresponding procedure forobtaining the dissociation constant of bases by the study of cellswithout liquid junction has been proposed,5* but apparently not yettested.55If it is required to study the actual extent of ionisation of a weakacid in the presence of an added salt, e.g., a chloride MCl, a t variousconcentrations, cells of the typehave been used; from the measurements the quantity KA =m,.rnAtl* in the salt solution may be determined. The values ofKA at 25", in solutions of chlorides a t the same ionic strength, havebeen found to decrease in the order BaCl,>LiCl>NaCl>KCl.These results may prove of importance in connexion with the'L secondary kinetic salt effect '' 56 in acid-base catalysis.Dissociation of Water.-A potentiometric method for the deter-mination of the ionic activity product of water, i.e., K , = %.aoH,,which does not involve liquid junctions, has also been devised : 57it depends on measurements with the cellAgIAgCl (s) NaCl (m,) NaOH (m,)lH,the E.M.F.of which, like that of the cell described on p. 101, isgiven byE = E, - (PtT/P)log,a,.a,,, . . . . . (12)where K is ~.aOH,IaEzO, that is Kw/agpo. Substituting the activities44 H. S. Harned and R. W. Ehlers, J. Arner. Chem. Soc., 1933, 55, 2377.45 D. D. Wright, ibid., 1934, 50, 314.48 MT. J. Hamer, ibid., p. 860.4 7 H. S. Harned and N. D. Embree, ibid., p. 1042.48 B. B. Owen, ibid., p. 1695.49 H. S. Harned and R. 0. Sutherland, ibid., p. 2039.50 L. F. Nims, ibid., 1933, 55, 1946; 1934, 58, 1110.6 1 D. A. MacInnes and D. Belcher, ibid., 1933, 55, 2630; 1935, 57, 1683.52 L. F. Nims and P. K. Smith, J.Riol. Chem., 1936,IIa, 145.63 L. I?. Nims, J . Arner. Chem. SOC., 1936, 58, 987.54 E. J. Roberts, ibid., 1934, 56, 878.5 5 See, however, H. S. Harned and B. B. Owen, ibid., 1930,52, 5079, 5091 ;66 H. S. Harned and F. C. Hickey, ibid., 1937, 59, 1284, 2303.57 E. J. Roberts, ibid., 1930, 52, 3877.€3. B. Owen, ibid., 1934, 56, 24104 GENERAL AND PHYSICAL CHEMISTRY.of the ions by the products of activity coefficient and molality,equation (13) becomesAs before, if the values of the left-hand side for various concen-trations of electrolyte are plotted against the ionic strength, theintercept obtained by extrapolation to infinite dilution gives bothK and K,, since h20 and the activity coefficients are then equal tounity. An alternative method for determining K, that does notrequire a knowledge of E, has also been used : it involves the em-ployment of the cells just described together with similar cellscontaining hydrochloric acid instea>d of sodium hydroxide.58 Thismethod has been adapted to the measurement of the activity ionicproduct of heavy water.59By re-arrangement, equation (14) may be written in the formRTP E - E, +-loge % =mOHnwhenceIf the value of ymyc1,, which is equal to the square of the meanactivity coefficient of hydrochloric acid at the total ionic strengthexisting in the cell, is known from measurements on cells containingthis acid, it is possible to determine ~ H ' ~ O H ~ / ~ 2 0 , i e ., the " ionicactivity coefficient product " of water in the given cell, sinceall the other quantities are available.Further, since K , i.e.,~H.yoH.m,.m,H'/aa20, is known, for it is numerically equal to K , atinfinite dilution, it is possible to evaluate mH.moH, : this gives theactual extent of the dissociation of water in the solution present intheDissociation Constants and Temperature.-The dissociation con-stants of several acids have been observed to pass through a maximum58 H. S. Harned and W. J. Hamer, J . Amer. Chem. SOC., 1933, 55, 2194.5D E. Abel, E. Bratu, and 0. Redlich, 2. physilcal. Chem., 1935,173, 353.60 For applications, see H. S . Harned et al., J. Amer. Chem. Soc., 1932, 54,3112; 1933, 55, 2194, 2206, 4496; 1935, 57, 1873; 1937, 59, 1280, 3033,2304GLASSTONE : ELECTROCHEMISTRY. 105as the temperature is increased : this fact led to the developmentof the equationlogK - log K, = - a(t - 0)2 .. . * (17)relating the dissociation constant K at the temperature t to themaximum value K , at the temperature 0, the quantity a being auniversal constant. This equation appears to be applicable toglycine, alanine, and formic, phosphoric (second stage), propionic,chloroacetic, sulphuric (second stage),61 b u t y r i ~ , ~ ~ lactic,52and glycollic 53 acids.It has been suggested that the agreement of equation (17) with theexperimental results is to some extent fortuitous; by means of asemi-theoretical treatment, involving the empirical facts that theentropy change and the change in heat capacity for first-stageionisations are constant, the equationlogK = A + B / T - C b g T .. . (18)has been deduced.62 This can be shown to be virtually identicalwith equation (17), provided t and 0 be not too far from 25"; withwater, however, for which the maximum dissociation constantprobably occurs near 300°, the two equations give different results,equation (18) being preferable.If dissociation constants are determined over a range of tem-pcratures, then application of the van 't Hoff isochore gives the heatof ionisation ; the appropriate calculations have been made forvarious acids 43-53 and for water ; 6o and in several cases the resultshave been found to be of the same order as those determined calori-metrically.62 The heat of ionisation of water is of particular interestas it is numerically equal to the heat of neutralisation of a strongacid and strong base in dilute solution; values have been estimatedfor a series of temperatures from 0" to 60°, the results being probablymore accurate than the best calorimetric values.Activity Coeficients obtained by using Celts with Transport.-The E.M.F.method for the determination of the activity coefficientof an electrolyte in dilute solution is one of the most valuable, but ithas been limited in its application by the necessity of setting up acell " without transport " having its two electrodes reversible withrespect to the two ions of the electrolyte. Although this can bedone in many cases, it is not always possible, e.g., for nitrates, orconvenient, e.g., for salts of alkaline earth and other metals.A newmethod has, however, been developed by D. A. MacInnes 63 whereby81 H. S. Harned and N. D. Embree, J. Amer. Chem. SOC., 1934, 56, 1050,2797 (correction).63 A. S. Brown and D. A. MacInnes, ibid., 1935, 57, 1356; T. Shedlovskyand D. A. MacInnes, ibid., 1936,58,1970; 1937,59,603; D. A. MacInnes andA. S. Brown, Chsm. Rewkws, 1936,18, 335.62 K. 8. Pitzer, ibid., 1937, 59, 2365106 GENEXAL AND PHYSICAL CHEMISTRY.the activity of an electrolyte can be determined by means of cells" with transport,'' provided the transport numbers of the ions overthe concentration range to be studied are known. If the transportnumbers are constant, the E.M.F. of a cell of the typeAglAgNO,(c) i Ag~O,(c,)lAgis given by E = (2n&T/P) loge a/al, where n#a is transport numberof the anion, and a and al are the mean ionic activities in the twosolutions of silver nitrate.In actual practice the transport numbersare not constant, however, so the equation for the E.M.P. must bewrittenE =or dE =where f is the mean activity coefficient in terms of volume concen-tration, i.e., a = fc. The transport number at any concentrationmay be expressed aswhere nl is the value at some reference concentration cl. If thisvalue for n, is substituted in equation (20) and the resulting expres-sion integrated between the limits cl, i.e., the reference concentration,and any concentration c, it follows thatna=nl+An . . . . . (21)./A%. d log, c - '1 An.d(Alog,f) . . (22)n1 c1 n1 ClThe term A log,f is equal to bgef - Iog,fi, where fi is the meanactivity coefficient in the reference solution and hence may be takenas constant. The first two terms on the right-hand side of equation(22) may be evaluated directly from the experimental data, the thirdis obtained by graphical integration of An against log,c, from theknown variation of transport number with the concentration, andthe fourth term, which is small, is computed by similar integrationof An against A log, f, preliminary values of the latter quantity beingobtained from the first three terms of the equation.To convert theA logef values into actual activity coefficients based on the usualstandard, i.e., the coefficient approaches unity as the dilution isincreased, use is made of the Debye-Hiickel equation applicable todilute solutions, vix., - log,f = a f i / ( l + p&), where a is a uni-versal constant and p an adjustable one depending on the size of thQLASSTONE : ELECTROCHEMISTRY.107ions.constant, this equation may be re-written asFor dilute solutions, therefore, the plot of A log,f + C& against( A - Alogef)dF should be a straight line with intercept A andslope p; the value of A , which is required for the plot, is obtainedby a short series of approximations. The method has been used todetermine the mean activity coeficients of the ions in sodium,potassium, calcium, and hydrogen chloride, and silver nitrate solu-tions. When the E.M.F. of the concentration cell can be expressedin terms of a simple function of the concentration, as is sometimesthe case, direct substitution may be made in equation (20), which isthen integrated between the concentration limits of 0 and c, thecorresponding values of the activity coefficient being 1 andf.Thisprocedure has been used for silver nitrate solutions up to O - ~ N . ; 64the results, which do not involve the Debye-Hiickel equation, are inexcellent agreement with those obtained by the previous method.Cathodic and Anodic Phenomena.-Hydrogen overvoltage. Therehas been in recent years a revival of interest in the problems ofhydrogen overvoltage, partly because of the intrinsic importance ofthe subject and partly on account of its possible relationship to theseparation of hydrogen and deuterium by electrolysis.66 It isgenerally agreed that for a given metal the overvoltage (q), i.e.,the difference between the potential a t which hydrogen gas isliberated from a cathode and the theoretical, or reversible, value inthe same electrolyte, is related to the current density (C.D.), repre-sented by I, by the equationwhere a and b are constants.According to the older theories, whichattributed the overvoltage to the slowness of the reaction 2H --+ H,at the electrode, b should have a value of 2.302 x HeT/2P, Le.,0-029 at 17", whereas the modern viewpoint, which considers theslow stage to be H' + E + H,* i.e., the union between the ion andan electron is slow, requires b to be equal to 2.302 x 2RT/P, i.e.,0.116 at 17". At silver, gold, copper, mercury, and nickel electrodesin dilute acid, values of b approximately 0.12 have been found atordinary temperatures,66 but there is no general agreement on thisSince A IOgef = logef - log,fl = log,f + A , where A is aA log,$ + adC= A + P(A - Alog,f)dc .. . (23)r = n + b l o g I . . . . . . (24)64 D. A. MacInnes and A. S. Brown, Zoc. cit., ref. (63).G 5 See, e.g., J. A. V. Butler, 2. Elektrochern., 1938, 44, 55.66 E. Baars, Sitzungsber. Cfes. Bef6rd. Naturw. Marburg, 1928, 63, 213;F. P. Bowden and E. K. Rideal, Proc. Roy. SOC., 1928, A , 120, 59; S. Levinaand V. Sarinski, Acta Physicochim. U.R.S.S., 1937, 6, 491.* Although written H', it is probable that in aqueous solution the hydrogenion is H,O'108 GENERAL AND PHYSICAL CHEMISTRY.matter for b values from 0.072 to 0.126 and between 0.055 and 0-075have been reported for a mercury cathode in 2~-hydrochloric acidand 2~-sulphuric acid re~pectively,~~ whereas for copper b has beenfound to vary from 0.070 t o 0.116, and a figure as high as 0-3 has beenrecorded;6* high values have also been found for lead in acetic acidand for tantalum in sulphuric acid sol~tions.~g On the other hand,low values, vix., 0-025 and less, have been obtained for metals of lowovervoltage, e.g., platinum and palladium,66* 689 70 but there is atendency for them to increase with continued use of the cathodewhich becomes partly poisoned. The potential of a platinumcathode in potassium hydroxide solution increases with time, butwhen a steady condition is reached the b value is stated to be 0.11-0.12.71 This result should, however, be accepted with reserve, forthe experimental arrangement is open to criticism : not only didoxygen from the anode appear to have access to the cathode, butthe “ direct method ” of measurement was used with currents whichmust have exceeded 0.5 amp., thus introducing appreciable resistanceerrors. Mention may be made in this connexion of the developmentof a novel technique for the measurement of the potentials of polarisedelectrodes whereby this source of error is avoided.72It was indicated in a previous Report 73 that more than onemechanism appears to be necessary to account for all the facts ofovervoltage, and the results recorded above support this view. Forhigh overvoltage metals it seems probable that, at least at relativelyhigh C.D.’s, the discharge of hydrogen ions is the process whichdetermines the rate of hydrogen evolution, but at low C.D.’s, andespecially for metals with low overvoltages, e.g., platinum andpalladium, another process is the determining factor.When theenergy of adsorption of hydrogen atoms on a metal is appreciable,then the atoms can be deposited at a lower potential than thatrequired for the discharge of “ free ” hydrogen.65’ 74 If the rate ofdesorption of hydrogen from the surface in the form of molecules isG 7 St. von Nhray-Szabo, Naturwiss., 1937, 25, 12.6 8 K. Wirtz, 2. physikal. Chem., 1937, B, 36, 435.70 L. P. Hammett, J . Amer. Chem. SOC., 1924, 46, 7 ; C. A. Knorr and E.Schwartz, 2.Elektrochem., 1934, 40, 38; 2. physikal. Chem., 1936, 176, 161 ;M. G. Raeder and K. W. Nilsen, quoted by C. A. Knorr and E. Schwartz,Zoc. cit., 1936; see A., 1936, 1207; see also L. Iiandler and C. A. Knorr, 2.Elektrochem., 1936, 42, 669.T. Erdey-Grtiz and H. Wick, ibid., 1932, A, 162, 53.71 G. Masing and G. Laue, 2. physikal. Chem., 1936, 1’48, 1.7 2 A. Hickling, Trans. Faraday SOC., 1937, 33, 1540.73 Ann. Reports, 1933, 30, 37.74 J. A. V. Butler, Proc. Roy. SOC., 1936, A, 157, 423; cf. J. Horiuti and M.Polanyi, Acta Physicochim. U.R.S.S., 1935, 2: 505; J. Horiuti et al., Sci.Papers Inst. Phys. Chem. Res. Tokyo, 1936, 29, 223GLASSTONE : ELECTROCHEMISTRY. 109rapid, then the overvoltage will remain low ; in these circumstancesit can be shown that the overvoltage is a linear, instead of a logarith-mic, function of the C.D.75 At higher C.D.’s, and particularly withmetals for which desorption is slow, the discharge of ions to formadsorbed atoms can no longer keep pace with the requirements of thecurrent, the surface becoming saturated, and an alternative process,viz., the formation of “ free ” atoms, at a higher potential mustensue.The overvoltage will now vary with C.D. according toequation (24), b being approximately 0.12 at ordinary temperaturesas is frequently found.The slow change in cathode potential with time, which is a familiarphenomenon of overvoltage, has been attributed to the slow rate ofattainment of adsorption saturation ; 76 some writers have ascribedthe observation to changes in the electrode surface, e.g., inactivationof active centres,71 but this is regarded as improbable, for the effecthas been observed with a liquid mercury cathode.It should beemphasised that modern theories of overvoltage do not take suffi-ciently into account the influence of interfacial forces, especially forhigh-overvoltage metals, resulting from changes in the nature of theelectrolyte; it has been known for several years that certain batho-tonic substances lower overvoltage 77 and this ha’s been confirmedrecently for mercury with a solution of hydrochloric acid in ethylalcohol as electrolyte.78A theory of overvoltage which differs completely from thosedescribed above has been proposed to account for observalions madewith a dropping mercury cathode in electrolytes containing light andheavy water in various proportions : 79 this theory supposes theformation of molecules of hydrogen to take place through inter-action of the deposited atoms and hydrogen ions in solution.Since the latter are formed by the ionisation of water molecules, therate of this process, as indicated by the ionic product, is of import-ance.On the basis of these postulates an equation is deduced relatingthe overvoltage to the isotopic composition of the water. It isconcluded that the hydrogen-deuterium separation coefficientshould have a mean value of 5.4, the ratio of the ionic productsof the two isotopic forms of water, which should decrease to 2.7 inordinary water and increase to 50 in concentrated heavy water;76 J.A. V. Butler and G. Armstrong, J., 1934, 743; M. Volmer and H.Wick, 2. physikal. Chem., 1935,172, 429.7g St. von Naray-Szabo, ibid., 1937, 178, 356.7 7 See S . Glasstone, “ The Electrochemistry of Solutions,” 1937, pp. 427,7 8 S . Levina and M. Silberfarb, Acta Physicochim. U.R.S.S., 1936, 4, 275.7Q J. Nov&k, Coll. Czech. Chern. COM., 1937, 9, 207; J. Heyrovskf, ibid.,431.pp. 273, 346110 GENERAL AND PHYSICAL CHEMISTRY.this tvpe of variation with composition appears to be contrary toexperiment. 8oAnodic Oxidation. It has been generally accepted that in pro-cesses of electrolytic oxidation, as well as in reduction, each definiteelectrode potential stage corresponds to a different process : it is,therefore, somewhat unexpected to record that in the oxidation ofthiosulphate ions, in a buffered neutral solution, two stages ofpotential can be observed a t a smooth platinum anode, but thenature and efficiency of the oxidation process, vix., SOYo of tetra-thionate and 20 yo of sulphate, approximately, is independent of thepotential.81 The electrolysis commences at a potential of about0.8 volt, but after an interval of time, which is greater the smallerthe current, there is a rapid rise to a higher stage, about 1-5-1.6volt.The change of potential is not connected with impoverish-ment of the electrolyte, as has been but to changes in thselectrode, for previous anodic polarisation will cause the potentialto rise to the higher stage immediately after the commencement ofelectrolysis of the thiosulphate solution. Addition of small amountsof mercuric cyanide, e.g., 0.001~., also results in a rapid rise ofpotential, but the efficiency of oxidation is only affected to a, smallextent.Similar results have been obtained in the electrolysis ofsulphite solutions, the products being dithionate (40-60%) andsulphate (50-60y0) .83 Two different potential stages, withoutany apparent change in the nature of the products, have also beenobserved at a platinum anode in the oxidation of methyl alcohol,formaldehyde, formic acid,84 and ethyl alcohol.85In order to account for the independence of anode potential andthe oxidation efficiency, it has been suggested that hydroxyl ionsare primarily discharged at the anode and that pairs of the resultingradicals combine irreversibzy to form hydrogen peroxide : 20H' +2~ + 20H --+ H,O,.The latter can either oxidise it depolariserin the electrolyte, e.g., S,03" or SO3", or it can decompose intooxygen and water. It is supposed that this oxygen becomes asso-ciated with the platinum electrode and is responsible for its potential,the two stages corresponding to two modes of attachment. Theoxidation reactions occur independently, and the potentials are notindicative of these processes but of a simultaneous side reaction.Mercuric cyanide is strongly adsorbed, so that the platinum-oxygen80 Cf. 35. P. Applebey and G. Ogden, J., 1936, 163.81 S. Glasstone and A. Hickling, J., 1932, 2345.82 J.A. V. Butler and W. M. Leslie, Trans. Paraday Soc., 1936,32,435 (444).8s S, Glasstone and A. Hickling, J., 1933, 829.84 E. Miiller et al., 2. Elektrochem., 1923, 29, 264; 1927, 33, 561 ; 1928, 34,85 C. Marie and G. Lejeune, J. Chirn. physique, 1929, 26, 237.266, 704; S. Tanah, &id., 1929, 35, 38GLASSTONE : ELECTROCHEMISTRY. 111association of the first type does not occur; the stability of thehydrogen peroxide is, however, not appreciably affected and theanodic oxidation process is unchanged. The presence in the solutionof substances able to catalyse the decomposition of hydrogen per-oxide suppresses the oxidation efficiency and favours the rapid rise ofpotential which soon reaches that necessary for oxygen evolution.The change of efficiency resulting from the use of different electrodematerials can be accounted for in the same way.Under suitableconditions, ammonium molybdate can bring about a marked increasein the formation of sulphate when thiosulphate is oxidised : 86this is exactly analogous to the behaviour in the purely chemicaloxidation with hydrogen peroxide. Other evidence for the theoryof anodic formation of the peroxide is found in the increased propor-tion of oxygen obtained in the electrolysis of acidified solutions ofpermanganate and dichr~rnate.~’Some authors 82# 88 have preferred to consider the primary anodicprocess, in the electrolysis of solutions of S203”, SO3” and other ionsundergoing analogous oxidation, as being the discharge of theseions, the radicals subsequently reacting, e.g., S203” --+ 2~ + S20:,followed by S203 + S203” + S40s” ; or S203” __p E + S203 ,followed by 2S203’ --+ SaOs“.The influence of various addedsubstances has then been attributed to the deposition of oxides,e.g., of lead, manganese, and silver, on the anode which thus alterits nature. It is not easy to understand, however, why any changein the anode material should affect ionic discharge and the subsequentprocesses. This daculty is accentuated by the fact that the effectsare virtually the same for a number of oxidisable ions of differenttypes, e.g., sulphite, chloride, and acetate (see below). Further,some added substances, e.g., powdered silver, carbon, or iron andcopper salts, are able to influence the oxidation efficiency withoutforming any deposit on the anode. In the electrolysis of halidesolutions 89 the presence of catalysts for hydrogen peroxide decom-position produces a marked change in anode potential as well as inthe yield of halogen : it is not easy to account for these results on thebasis of the preferential discharge of halogen ions, since this is areversible process and should be independent of electrode material.The observations are, however, in harmony with the view thathydroxyl-ion discharge also occurs, leading to the formation ofhydrogen peroxide which acts as the oxidising agent. The sug-gestion has been made 88 that the behaviour of different electrode8 6 S. Glasstone and A. Hickling, J., 1932, 2800.8 7 A. Hickling, J., 1936, 1453.88 0. J. Walker and J. Weiss, Tram. Paraday Soc., 1935, 31, 1011; W. D.88 S. Glasstone and A. Hickling, J., 1934, 10.Bancroft, Trans. EEectrochem. SOG., 1937, 71, Preprint 7,53112 GENERAL AND PHYSICAL CHEMISTRY,materials in the oxidation of ions may be explained by the differencein anodic overvoltages, but this does not seem to be in harmony withthe experimental facts.90The anodic oxidation of chromic salts to chromic acid has longpresented a diflicult problem : the process occurs more readily a tlead dioxide and platinised platinum anodes than at one of smoothplatinum, in spite of the higher potential of the latter. A recentinvestigation 91 has shown that for electrolysis in acid solutionfactors which would tend to decompose hydrogen peroxide favourthe oxidation reaction : this is to be expected, since the peroxide isable to reduce chromic acid to chromic ions. The actual oxidationin these circumstances is apparently brought about by active oxygenthrough the intermediate formation of metallic peroxides. Inneutral and alkaline solutions, however, the results are quite dif-ferent for, in addition to this type of process, hydrogen peroxide canalso oxidise the chromic ions. The interesting results obtained inthe electrolysis of solutions of chromic salts can be explained in asatisfactory manner on the assumption that hydrogen peroxide isformed a t the anode, although it is not necessarily the effectiveoxidising agent, but do not seem capable of any other simple inter-pretation. It may be appropriate to emphasise here that otheranodic reactions are known in which hydrogen peroxide does notappear to be the essential oxidant.92The formation of hydrogen peroxide by the combination of hydr-oxyl radicals in the gas phase is generally accepted,93 but the produc-tion of the peroxide from hydroxyl ions at the anode in solution isnot commonly observed; this is probably the result of catalyticdecomposition by the anode material. At low temperatures,Mhowever, or in the presence of fluoride ionsY95 which act as a catalyticpoison, appreciable amounts of hydrogen peroxide have been ob-tained at platinum anodes in the electrolysis of solutions of alkalihydroxides. The formation of the peroxide, in amounts corre-sponding to the requirements of Faraday’s laws, has been observedwith a glow-discharge anode; 96 the electrode is then not immersedin the solution and catalytic decomposition is prevented.S. Glasstone and A. Hickling, Trans. Faraday SOC., 1935, 31, 1656.91 R. F. J. Gross and A. Kickling, J., 1937, 325.92 S. Glasstone and A. Hickling, “ Electrolytic Oxidation and Reduction,”1936, pp. 336-338, 350.08 W. H. Rodebush and M. H. Wahl, J . Chem. Physics, 1933, 1, 696; 0.Oldenberg, ibid., 1935, 3, 266; R. W. Campbell and W. H. Rodebush, ibid.,1936, 4, 293.84 E. H. Riesenfeld and B. Reinhold, Ber., 1909, 42, 2977.96 Riw 9 Miro, Helv. Chim. Acta, 1920, 3, 355.O 6 5. Glasstone and A. Hickling, J . , 1934, 1772; see also A. Klemenc andT. Kantor, 2. physikal. Chem., 1934, B , 2’9, 359GLAqSTONE : ELECTROCEEMISTRY. 113The Kolbe Reaction. Since the discovery in 1849 that ethane andcarbon dioxide are obtained by the electrolysis of aqueous solutionsof acetates, the electrolytic Kolbe reaction has attracted muchattention and two main theories of its mechanism have been held.These are (1) that acetate ions are directly discharged at the anode,the radicals then interacting, thus : 2CH3-CO*O* + C2H, + 2C0, ;and (2) that active oxygen is first produced and this oxidises theacetic acid or acetate ions to acetyl peroxide which then decomposesto give ethane and carbon dioxide. The supporters of the respectivemechanisms have put forward a large amount of experimental evid-ence in favour of their apparently opposing views : 97 it is, therefore,of interest to mention that a comprehensive theory, involving boththe above, together with the concept of the anodic formation ofhydrogen peroxide, has been proposed.g8 To explain a, variety ofobservations, e.g., influence of anode material and of added sub-stances, it is suggested that in aqueous solution the hydrogen per-oxide first produced reacts with the acetate ions to form acetateradicals ; these combine in pairs yielding acetyl peroxide, whichsubsequently decompose^,^^ thus :H,O, + BCH,*CO*O’ --+ 20H’ + 2CH3*CO*O* +In the presence of catalysts for hydrogen peroxide decomposition, orif the acetate-ion concentration at the anode is kept low, e.g., whenacetic acid solutions are electrolysed in the presence of small amountsof neutral salts, an alternative process occurs. The hydrogen peroxide,or active oxygen, oxidises the acetic acid, or acetate ions, to peraceticacid, which on decomposition gives methyl alcohol :The formation of this substance, known as the Hofer-Moest reaction,has been confirmed under the conditions mentioned. In non-aqueous solutions the formation of hydrogen peroxide is not possible ;direct discharge of the acetate ion must then occur, with the conse-quent formation of acetyl peroxide and finally the decompositionproducts of the latter, thus :ZCH,-CO*O‘ + 2~ + 2CH3*CO*O* --+A side reaction which sometimes occurs is oxidation of the non-aqueous solvent by the acetyl peroxide, thus decreasing the yield of(CJ&j*CO*O*),+ C2HG + 2C02.CH3*CO*OH + [O] .+ CH,*CO*O*OH + CH,*OH + CO,.(CH3*CO*O*), --+ C.3, + 2C0,.Q7 For summary, see S. Glasstone and A. Hickling, op. cit., Chapter VIII.98 Idem, J., 1934, 1878; 1936, 820.SQ For evidence collected by F. Fichter and collaborators, see S. Glasstoneand A. Hickling, op. cit., pp. 293-296 ; also, H. Wieland et al., Annalen, 1934,513, 93; 0. J. Walker and G. L. E. Wild, J . , 1937, 1132114 GENERAL AND PHYSICAL CHEMISTRY.ethane. Amongst the many achievements of the theory may bementioned its interpretation of the hitherto perplexing fact thatalthough the Kolbe reaction at a platinum anode takes place equallywell in aqueous and non-aqueous solutions , with a gold electrodethere is no formation of ethane in aqueous solution although it isproduced with a high efficiency in non-aqueous media. In aqueoussolution a gold anode becomes covered with a layer of oxide which is avery effective catalyst for the decomposition of hydrogen peroxide,so that the Kolbe reaction is inhibited ; the oxide, however, appearsto have little influence on the stability of acetyl peroxide and hencethe formation of ethane should occur in non-aqueous solutions.Some observations have been made recently of the electrolysis ofacetic acid and potassium acetate in deuterium oxide, and ofdeuterium trideuteroacetate and sodium trideuteroacetate in water ;1only when the deuterium is present in the acetic acid, or acetate, doesthe ethane evolved contain any appreciable amount of this isotope.The results appear to throw little light on the mechanism of theKolbe reaction; they merely show that if methyl radicals are anintermediate product in the formation of ethane they do not reactwith the solvent. Electrolysis of different deuteropropionic acids 2may, however, provide a clue as to the origin of the ethylene, whichis one of the chief products in aqueous solution : this is, however, adeviation from the usual type of Kolbe reaction. S. G.J. A. V. BUTLER.S. GLASSTONE.M. RITCHIE.W. F. K. WYNNE-JONES.1 H. Erlenmeyer and Vi. Schoenauer, Helv. ChE.irn. Acta, 1937, 20, 222;3 Idem, Ber., 1937, 70, 819.P. Holemann and K. Clusius, 2. physikal. Chern., 1937, B, 35, 261

ISSN:0365-6217    

DOI:10.1039/AR9373400030

出版商:RSC    

年代:1937

数据来源: RSC

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INORGANIC CHEMISTRY.1. THE METAPHOSPHATES AND POLYPHOSPHATES OF SODIUM.THE alkali metaphosphates comprise one of the most complicatedand puzzling groups in Inorganic Chemistry. Successive workershave added to rather than lessened the chaotic state. The complexnature of the phosphorus molecule is shown, however, not only inthese compounds but also in the element itself and in its oxides,especially the pentoxide,2 and an understanding of the nature ofthe latter and of the different complex states it can assume mightwell provide a key to the structure of its derivatives. On the otherhand, there seems little doubt that the problem has been mademore difficult by lack of strict analytical control of the initial andfinal products. Owing to the diverse values given to relativelysimple physical constants, one is forced to conclude that impure oreven very impure materials were being used in many cases.Although it is impossible at present to give a completed story ofthe metaphosphates, no apology is necessary for discussing themowing to the enormous importance they have acquired in the lastfew years in industry, especially in connection with the soMeningand conditioning of boiler-feed water, in removing calcareousdeposits from boiler-feed tubes, in the laundry and the textileindustry and in tanning processes.Their use in these diversefields is based on the remarkable fact that the so-calledhexametaphosphates (and one or two polyphosphates) will formsoluble complexes with calcium salts, the calcium becoming anessential part of a very stable un-ionised complex, which permits ofthe calcium-ion content of a water being reduced to a scarcelymeasurable value.The metaphosphates were first prepared in 1833 by T.Graham:who pointed out that when sodium dihydrogen phosphate ordisodium dihydrogen pyrophosphate was heated to 315" asparingly soluble metaphosphate was formed. When this washeated to a higher temperature it fused and, as Graham noted,"on cooling it presents itself as a transparent glass whichdeliquesces in a damp atmosphere and is highly soluble in water.But the fused salt has undergone a most extraordinary and1 Cf. Ann. Reports, 1935, 32, 156. a Cf. i b d . , 1936, 83, 185.8 Phil. Trans., 1833,123, 253116 INORGANIC CHEMISTRY.permanent change of properties.The solution has a very feebleacid reaction when compared with the crystallised biphosphate,”the initial substance. Further, he found that when the solutionwas evaporated at 40°, a gum-like mass was obtained which, ifdried at 204”, consisted of pyrophosphate with some water. Theaqueous solution seemed perfectly stable at ordinary temperaturesand was not much affected by boiling with dilute alkali. Theglassy mass was insoluble in alcohol, and when its solution wasmixed with metallic or alkaline-earth salts voluminous gelatinousprecipitates were produced.The formation of the transparent glass only follows when coolingis fairly rapid. Slow cooling results in crystallisation ; a compound,usually considered the trimetaphosphate, is formed, which has nopower of sequestering calcium ions (but see Kurrol salts, p.117).Graham’s original method of preparation of metaphosphates isthe one used technically to-day. Of the other methods, only oneneed be mentioned-that due to G. von K n ~ r r e . ~ This consists oftreating phosphoric acid on the water-bath with a concentratedsolution of sodium nitrate and then heating the mixture to 330”.Purification can be effected by conversion into the lead salt anddecomposition of this with sodium sulphide. The form so obtainedis usually referred to in the literature as Knorre’s salt.It was early realised that in the change from the insoluble intothe soluble hexametaphosphate or Graham’s salt, a number oftransitions were involved, and attempts were made to explain thesechanges on the assumption that phosphates of increasing molecularcomplexity were formed.The initial insoluble form made at lowtemperatures-commonly referred to as Maddrell’s salt 5-wasconsidered by T. Fleitmann and W. Henneberg6 to be themonomer, as they failed to prepare from it any double salts; theyclaimed, however, to have prepared di-, tri-, and tetra-metaphos-phates, usually by controlled heating and subsequent extractionwith water. The question of the chemical entity of thesecompounds has been the subject of many papers which cannot bediscussed here. The evidence in favour of their existence is basedon (a) formation of double salts, (b) molecular-weight determin-ations (ionisation sometimes considered and sometimes not), and(c) equivalent conductivities of solutions, chiefly the differences inthis property for solutions of dilution v = 32 and v = 1024.The view that Graham’s salt, Le., the product obtained by rapidcooling of the fused mass, is a hexametaphosphate rests partly onthe early work of H.Rose,7 who prepared from it a double silverR. Maddrell, Phil. Mag., 1847,30, 322.Pogg. Ann., 1849, 76, 1.8. anorg. Chem., 1900, 24, 397.Annalen, 1848,65, 328TERREY : METAPHOSPHATES AND POLYPHOSPHATES OF SODIUM. 117sodium salt (AgsNaPeOls), on the Iater work of G. Tammann,*who measured the electrical conductivity of aqueous solutions, andon molecular weights calculated from the lowering of the freezingpoint of aqueous solutions by L.Jawein and A. T h i l l ~ t . ~ Tammannfurther inferred from his conductivity work that sodium hexameta-phosphate normally behaved as a salt of a dibasic acid andsymbolised it as Na,[Na,P,Ol,f. He also considered that Graham'ssalt was a mixture of a t least three different isomeric compoundswith different amounts of sodium in the anionic complex. In additionhe claimed to have made a second soluble form of the monomer(p-form) by neutralising metaphosphoric acid with sodiumcarbonate and evaporating the solution a t 50". This form wasreadily soluble in water and easily changed into orthophosphate.Sodium metaphosphate melts normally a t a temperatureEomewhere between 610" and 640' (610", van Klooster; 619",Jaeger; 640", Pascal).By judicious heating it is said to bepossible to bring about the formation of a crystalline salt whichwill not fuse until a temperature of over 800" is reached. Themodifications existing between the normal melting point and thishigher fusing temperature have been looked upon as octa-salts andare usually classed under the name "Kurrol" salts. Thepreparation in this way seems to be capricious, although as will beseen later, P. Pascal claims to have accurately defined conditionsunder which they can be made. They resemble Maddrel17g salt inbeing insoluble in water, but differ in that with aqueous pyro- andhexa-metaphosphate, in which they are soluble, they givesolutions with a very high viscosity. It should be mentioned thathigher condensed salts, e.g., decametaphosphates, have beendescribed. l1During 1923 and 1924 a series of papers were published byPascal l2 dealing with this subject.His researches are discussedhere only in so far as they relate to the monomer and Kurrol saltsand to the changes which he supposed sodium phosphate underwenton being heated to the fusing point.By allowing water-free ether to act on phosphoric anhydride,Pascal prepared ethyl metaphosphate, presumably in the condensedstate, for he formulates it as the hexa-ester. This ester was runslowly into a solution of sodium ethoxide, the temperature notbeing allowed to exceed' 40". Sodium metaphosphate containingsodium ethoxide was obtained as a tough, transparent, faintlybrown mass. Washing with alcohol, ether, and chloroform8 J .p r . Chem., 1892, 45, 463.10 Cornpt. rend., 1924, 173, 211.12 Compt. rend., 1923, 176, 1398; 1924, 178, 1541, 1906.Rer., 1889, 22, 655.l1 Tammann, Zoc. cit., ref. ( 8 ) 118 INORGANIC CHEMISTRY.removed the ethoxide and unchanged esters, and heating the residuein a vacuum afforded quite pure metaphosphate. It is crystallineand easily soluble in water to give a neutral solution exhibiting allthe characteristic reactions of metaphosphate. Measurements ofthe molecular weight gave a value of 51, which would indicate thatthe salt was completely dissociated. The properties of the saltwere not affected by heating to 600". He concluded thatMaddrell's salt, previously regarded as the monomer, had, owingto the method of formation, already undergone condensation to apolymer .13Pascal stated that the Kurrol salts can be made with certaintyby allowing fused Graham's salt to supercool to 550", seeding themass with crystals obtained from the ignition of monosodiummethyl or ethyl phosphate, and then reheating it cautiously inorder to accelerate crystal growth.Under these conditions thewhole mass is converted into the crystalline, insoluble form. Itcan be heated to 809-811" before fusing, whereupon a liquid isformed which he considered to be essentially different from thatobtained by fusing Graham's salt. On cooling, whether a glass ora crystalline solid was formed, the product was insoluble. Additionof traces of hexametaphosphate to the fused mass resulted in itsconversion on solidification into the soluble form.The capriciousnature of the reverse change has already been mentioned.On heating Kurrol salts to different temperatures rangingbetween 600" and 800" and dissolving the products in salinesolutions, particularly in pyro- and hexameta-phosphates, heobtained viscid liquids. From observations that the viscosityincreased per saEtum according to the temperature to which theKurrol salt had been heated, it was deduced that a t least threedifferent modifications were formed. The elastic solids noted byFleitmann and regarded by Tammann as penta- or deca-metaphos-phates were looked upon by Pascal as Kurrol salts mixed withhexametaphosphates.From a study of the products obtained by heating Maddrell'ssalt to different temperatures and then quenching them in mercury,and taking into account the possible formation of Kurrol salts,Pascal summarised the changes which occurred as follows :Kurrol I1 Kurrol I11,+'-'I 21 j 8100601° 607O 640° .5.Maddrell _I, Tri-salt Tetra-salt -= Hexa-salt - - - Liquid(liquid)13 Cf.P. Nylen, 2. anorg. Chem., 1936, 229, 30TERREY : METAPHOSPHATES AND POLYPHOSPHATES OF SODIUM. 119The tetrametaphosphate has a relatively small range of existence.It can undergo change in two ways, giving the fused hexa-salts at640" or Kurrol salts at 595", fusion in the latter event not occurringuntil 810".In the last two years attempts have been made to follow thechanges by using rather more precise methods. The moreimportant of these include (a) X-ray investigations of the productsformed and ( b ) differential thermal analyses on heating and cooling.In the X-ray work, A.Boull6 l4 carried out two series of experimentson the products obtained by (i) dehydration of Na,H,P,O, up tothe melting point, or by (ii) annealing at different temperaturesthe vitreous mass got after fusion. His results may be summarisedas follows.Above 250°, insoluble Maddrell's salt or m8taphosphate-A' wasformed ; this has a distinct structure. By raising the temperatureabove 400" but keeping it below 550", an insoluble metaphosphate-Bwas formed, again with a characteristic structure. The formationof this modification below 400" was very slow-at 3S0°, even afterseveral days the spectra showed that it was a mixture of A' and B.Above 550" up to the fusing point, a soluble metaphosphate-A wasformed; this gave an X-ray spectrum identical with that of A'.Fusion of A', B, or A followed by rapid cooling gave a vitreousproduct C, which lacked structure.Tempering of C resulted incrystallisation, and whether this was carried out a t 300", 330°, 450",d90°, or 625", the same soluble metaphosphate-A was recovered.The reversible transformations recorded by Pascal seemed non-existent. A metaphosphate prepared by Knorre's method (usuallyconsidered to be the trimer) afforded an X-ray spectrum identicalwith that of A.obtainedresults which supported the X-ray investigations. In thedehydration curve two transformations were distinctly shown :(1) at a temperature of about 430°, corresponding to the passagefrom the A' to the B form; and (2) extending over the range550-590", depending on the rapidity of heating, brought aboutby the change from the insoluble B into the soluble A form.Neither change was reversible, the cooling curve indicating onlythe transformation from the liquid to the solid state A.If theheating were stopped before fusion (625") and the product allowedto cool, a smooth curve was obtained and no changes could bedetected. Heating of Knorre's salt or the product A (obtainedfrom Na2H,P207) up to the melting point failed to reveal anytransitions. Boull6 postulated the following changes, withoutIn the differential thermal analysis the same author54 Compt.rend., 1935, 200, 658. 16 Ibid., p. 832120 INORGSNIC CHEMISTRY.attempting to associate any modification with any molecularmagnitude :Na2H2P20, --+ Meta-A' + Meta-B + Meta-ANo indications were obtained of the transformation associatedby Pascal with the tetra-form. The view that this salt is non-existent has been challenged by P. Bonne?nan.lG Following thetechnique described by F. Warschauer,l7 which consists in heatingto a temperature not exceeding 400" a mixture of copper oxide andorthophosphoric acid and precipitating the copper subsequentlywith sodium sulphide, he obtained a product with an X-raystructure distinct from that of the trimetaphosphate and which,from cryoscopic determinations with fused hydrated sodiumsulphate as the so!vent and from conductivity measurements,agreed with the formula Na4(P03),.On fusion it gave Graham'ssalt. At ordinary temperatures it must be in a state of unstableequilibrium (Pascal). This was demonstrated by annealing : a t375" it was partly, and at 500" completely, converted into thetrirner.Most observersagree on the existence of the trimer. This can apparently exist intwo forms, one of which is soluble, resulting from the crystallisationof fused phosphate or from Knorre's preparatlion, and the otherinsoluble-the so-called Maddrell's salt. From the nature of thecompounds derived from it, Graham's salt is most simply regardedas the hexameta-salt. Beyond these two, there is no real evidencefor the formation of compounds in the dehydration of either themonohydrogen orthophosphate or the dihydrogen pyrophosphate.The changes noted in X-ray structure and in the thermal analysescannot satisfactorily be connected with changes in the extent ofthe polymerisation.Little can be said definitely with regard to the nature of thecomplexes formed by Graham's salt owing to the uncertainty withregard to its constitution and molecular state.If it is assumed tobe the hexametaphosphate, then one molecule of this will reactwith one of a calcium or barium salt to form the soluble complex :LiquidTo attempt to sum up the situation is not easy.N'dNa2(PO3)t.J + Gas04 + Na4[Ca(P03)6] + Na&304or (as more usually written)with sodium and calcium both forming part of the complex anion.Both of the above forms were postulated by Tammann, but the18 Compt.rend., 1937, 204, 865. l7 2. anorg. Chem., 1903, 36, 137TERREY : METAPEOSPHATES AND POLYPHOSPHATES OF SODIUM. 121reasons given in support of these structures are not very con-vincing.Of great importance in the technical use of metaphosphates isthe question of their stability, i.e., the speed of their conversion insolution into the trimeric form or into pyro- and ortho-phosphates,for the trimer and the orthophosphate have no power of removingcalcium ions and the pyrophosphate possesses this property only toa slight extent. This problem has been investigated by L. Germain,l8who carried out measurements on the loss of sequestering power ofdilute solutions towards barium salts, (i) alone and (ii) in contactwith acids and alkalis, for different periods and a t different temper-atures.He found that temperature plays a very important part inthe rate of change. Cold solutions are stable, but at the boilingpoint complete conversion was reached in a few hours. Additionof acids increased the velocity of change at all temperatures.Hydrolysis gave primarily sodium dihydrogen phosphate, so exceptin buffered solutions there is a marked decrease in the value of thepH of the solution, the reaction in water being therefore auto-catalytic. The presence of small amounts of sodium hydroxide orcarbonate, as noted by Graham, reduced the rate of change.PoZyphosphates.-Allied to the metaphosphates are the polyphos-phates of the general formula Nan + 2P,03n + produced by heatingtrisodiurn hydrogen pyrophosphate : l9or by fusing together metaphosphate and pyrophosphate : 20Na4P,07 + NaP03 --+ Na5P3O1,Na4P,07 + 2NsP03 -+ Na6P,Ol3These compounds, like Graham’s salt, possess the property offorming un-ionised calcium derivatives and have a correspondingapplication.There is still considerable controversy as to whetherthey are definite chemical entities or merely mixtures of the twocomponents. There is no evidence for compound formation whenthe two solutions are mixed, and no indication of compounds wasobtained from a thermal study of the Melts cooledquickly give an amorphous glass in which are embedded crystals ofnormal sodium pyrophosphate, and the same compound invariablyseparates on slow cooling.On the other hand, Huber has claimedthat by prolonged annealing of the vitreous mass a transformation18 Chirn. et Ind., 1936, 35, 22.19 J. R. Partington and H. E. Wallsom, Chem. News, 1928, 136, 97.20 F. Schwarte, 2. anorg. Chem., 1895, 9, 249; M. Stange, ibid., 1896, 12,444; H. Huber, ibid., 1936, 230, 123; Angew. Chem., 1937, 50, 323.21 N. Parravano and G. Calcagni, 2. anorg. Chem., 1910, 65, 1122 INORGANIC CHEMISTRY.in the solid state takes place. The temperature and time requisitefor this change are not definite, but depend on the size of thepyrophosphate crystals in the fused mass. At the melting pointthe compound Na5P301, is converted into Na,P,O, and anamorphous polyphosphate. In support of his views he adduces thefact that the dispersive action on calcium soaps increased withcontinued annealing’ and secondly, that it was possible to isolatefrom the aqueous extracts definite salts, e.g., Na6P3010,Na3H,P3Qlo,3H,0, or the corresponding zinc saltZnaNaP3Olo, 96H,O ,formed almost quantitatively when zinc acetate is added to anacetic acid solution of the sodium salt. Compounds of the sametype have also been prepared by Bonneman,16 e.8.’Na3CdP3010, 12H,O and Na2CrP3O1,,6H,O.H.T.2. ANOMALOUS VALENCY IN THE RARE-EARTH ELEMENTS.As stated in last year’s Report, in which this subject was brieflydiscussed, “ it is now & d y established that valencies of two andfour are possible with some of the rare-earth elements, although itis still. correct to say that the characteristic valency of the groupis three.” These elements are therefore properly placed togetheras one in the third group of the Periodic Table.A further reviewof the subject has appeared in which the interpretation of anomalousvalency in terms of electronic configuration, based on magneticand optical data, is discussed. These two reviews give a verycomplete list of references to the literature of the subject coveringthe period up to about 1936.The interpretation of anomalous valency in terms of electronicstructure, the investigation of new or doubtful examples, and theapplication of well-established cases of anomalous valency toprovide more rapid methods of separation and purification of therare-earth elements, continue to excite interest and justify a surveyof the most recent work in this field of investigation.Our present knowledge of the occurrence of bi- and quadri-valencyamongst the rare-earth elements is still well summarised by thediagram of Jantsch and Klemm, reproduced in last year’s Report,or by the following table, due to P.W. Selwood,2 which shows theiso-electronic arrangement of the rare-earth ions for the well-established cases of abnormal valency :1 D. W. Pearce and P. W. Selwood, J . Chem. Educ., 1936, 13, 224; cf.2 J . Amer. Chem. SOC., 1934, 56, 2393.also D. W. Pearce, Chern. Reviews, 1935, 16, 121TERREY AND WALKER : ANOMALOUS VALENCY. 123TABLE I.Iso-electronic Arrangement of the Rare-earth Ions.No. of ?lectrons No.of electrons Spectroscopicin ion. in 4f shell. term. Ions.64 0 1s La3+ Ce4+55 1 2F5/2 ~ e 3 + f ~ r 4 +56 2 3H457 3 41rt~a58 4 b459 5 6 H s l a62 8 '3663 9 6%J a64 10 "*65 11 4 1 i 5 ~ a66 12 3H667 13 2 3 7 / aPr3+ f113+Nd3+Sm3+Sm2+ gE~3+Tb3+fDy3+Ho3+Er3+lcTm3+? Y b 3 +Yb2+ gLu3+:3 En2+ )(Gd3+ Tb4+60 661 768 14 1sAs regards bivalency, the possibility of its occurrence withlanthanum, neodymium, gadolinium, thulium, and lutecium hasbeen suggested, but no direct positive evidence has been obtained.There is, however, scme reason to believe3 that bivalent thuliumhas a transitory existence during the reduction of anhydrousthulium trichloride to the metal.There is more uncertainty with regard to the occurrence ofquadrivnlency in elements other than cerium, praseodymium, andterbium, all of which form oxides MO,, obtained by ignition of thelower oxides or of some of their salts. In the case of the last twometals, however, fusion with an alkali nitrate or in an atmosphereof oxygen is necessary for complete oxidation, and, in spite ofmany attempts, it has not been possible to prepare any Pr*+ andTb4+ salts, analogous to the well-known ceric salts, since the higheroxides are decomposed under the action of acids with formation oftervalent salts.The view that neodymium can form quadrivalentcompounds4 has not been confirmed by G. Jantsch and E.Wiesenberger. They have extended their investigations into thepossible formation of higher-valency compounds of the rare-earthmetals to the case of dysprosium, which, since it bears the samerelationship to terbium as praseodymium does to ceriuni (cf.TableI), might be expected to form a higher oxide. They find that X-rayspectroscopically pure Dy,U, shows no appreciabie gain in weightwhen heated in oxygen or air at 300-1000", whilst Dy,O, con-taining a little Tb,O, shows only a slight gain. The productobtained by fusion of Dy,03 in potassium and sodium nitrates and3 G. Jantsch, N. Skdla, aad H. Grubitsch, 2. anorg. Chem., 1933, 212, 66.4 A. Brukl, Angew. Chem., 1936, 49, 533.5 Monatsh., 1936, 68, 394124 INORGANIC CHEMISTRY.in pota,ssium chloride, after removal of solid matter, contains nohigher oxide which liberates iodine from potassium iodide.W.Klemm and A. Koczy6 have shown that the oxides oflanthanum, cerium, and praseodymium, when treated with hydrogenselenide for about 5 hours a t 600-1000", are converted quanti-tatively into polyselenides of the type M,Se4. Neodymium formsan impure polyselenide, and the other elements give the normalselenides M,Se,. The polyselenides form iSI2Se3 when heated in avacuum. As in the case of the poly~ulphides,~ magneticsusceptibility and other evidence shows that the polyselenidescontain tervalent cations. They are not, therefore, abnormalvalency compounds and are best represented as M,Se,-Se.An investigation of the atomic volumes of the rare-earth elementsin the metallic state by W. Klemm and H. Bommer has disclosedsome important relationships regarding the abnormal valencystates of these elements.By means of X-ray methods, theseauthors have examined the lattice structures of all the rare-earthmetals, except holmium, using a mixture of the metal with3RC1 (R = Na, K, Rb, Cs) obtained by reduction of the rare-earthtrichloride with liquid alkali metals. When the atomic volumescalculated from the lattice-structure data are plotted against theatomic number an interesting periodicity is revealed. The valuesof the atomic volume can be regarded as lying or tending to lie onthree distinct curves, vix., the broken curves 11, 111, and IV ofFig. 1, which is reproduced from Klemm and Bommer's paper.The meaning of these curves is interpreted by them on theassumption that the rare-earth metals are built up from positiveions and an electron gas of valency electrons.Curve I11 containsthe atomic volumes of those elements which show only the normalvalency of three and contain only triply charged ions and threevalency electrons per atom in the metal. One would expect tofind a gradual decrease in atomic volume with increasing atomicnumber (lanthanide contraction), and actually the decrease fromlanthanum to lutecium is 4.5 C.C. The curve is made up of twoparts, vix., from lanthanum to gadolinium and from gadolinium tolutecium, corresponding with the usual sub-division of the rare-earth elements into two groups. Curve I1 joins the atomicvolumes of europium and ytterbium to that of barium, and it isconcluded that these two rare-earth metals contain mostly doublycharged positive ions, corresponding with their ready tendency toform bivalent compounds.For samarium, the third element of6 2, anorg. chn., 1937, 233, 84.7 W. Klemm, K. Meisel, and H. U. von Vogel, ibid., 1930, 190, 123.8 Ibid., 1937, 231, 138TERREY AND WALDR : ANOMALOUS VBLENCY. 125this type, the atomic-volume data are uncertain, but it seemsprobable from the greater instability of its bivalent compoundsthat the value of its atomic volume must lie somewhere betweenthat of europium and Curve 111. The lowest curve, IVY purportsto represent the atomic volumes of metals consisting entirely ofM4+ ions, and its position is determined approximately by theexperimentally determined point for the atomic volume of hafnium.FIG.1.The three metals which can form quadrivalent compounds, wiz.,cerium, praseodymium, and terbium, all have atomic volumes lyingbelow the normal curve 111, and this is especially marked withcerium. The atomic-volume curve reproduces, therefore, the mainwell-established features of abnormal valency in the rare-earthelement^,^ vix., that (1) the tendency towards bivalency is greaterthan that towards quadrivalency, and (2) the occurrence ofabnormal valency (both bi- and quadri-) is more noticeable in thefirst group (La --+ Gd) than in the second (Gd + Lu).Klemm and Bommer have deduced similar conclusions from9 Cf. Ann. Reporb, 1936, 33, 179 (diagram)126 INORGANIC CEEMISTRY.measurements of the magnetic susceptibilities of the rare-earthelements in the metallic state.The susceptibility of the metal willbe determined practically only by the paramagnetism of thepositive ions, since their diamagnetism and the weak temperature-independent paramagnetism of the electron gas can be neglected.Thus the paramagnetic behaviour of the metal will depend onwhether it contains only M3+ ions, or also M2+ or M4+ ions, and itshould be possible to determine what ions are present in any metalfrom magnetic measurements. The problem is complicated bythe occurrence of ferromagnetic phenomena in the yttrium-earthmetals, and the results are best discussed by considering thefollowing two groups of elements separately.These metals have no ferromagneticproperties. The effective magnetic moment, p&., is derived fromthe atomic susceptibility, Xat., by the expression pee.= 2-841/xat. . T,where T is the absolute temperature. The values so obtained canbe compared with the moments pcalc. of the various ions, whichcan be calculated from spectroscopic theory 10 and agree withthe values obtained experimentally from measurements with solidsalts such as M2(SO4),,8H,O. The values of pdf. at roomtemperature found by Klemm and Bommer, and those of pcalc.which they quote, are given in Bohr magneton units in Table 11.(1) Lanthanum-samarium.TABLE 11.pca1c..r--- Ipelf.. MA+. M3+. Ma+.- La, ..................... very small - 02-56 - Ce ..................... 2.34 0- 3-61 - Pr ..................... 3.22Nd ..................... 3.56 3.62 3.66 2.8 .....................1-55 3.40 Sm 2.07 -Lanthanum is very weakly paramagnetic, as is to be expected ifit contains only La3+ ions. Cerium has a value of peff. intermediatebetween those of pcdc. for Ce3t and Ce4+, but much nearer theformer, indicating a preponderance of Ce3+ ions. With neodymiumthe result is not so satisfactory, since pdf. is in reasonableagreement with either Nd3+ or Nd4+, both of which have practicallythe same value of pcalc.$ but at any rate Nd2+ can be excluded.For samarium the result suggests that, although it consists mostlyof Sm3+, yet the proportion of Sm2+ is considerable, wix., more than20%. The value of pa. found for praseodymium is the only reallyanomalous one, since it indicates almost equal proportions of Pr3+and PI?+ in the metal, which is contrary to other evidence.Thelo Cf. J. H. van Vleck, “The Theory of Electric and MagneticSusceptibilities,” 1932TERREY AND WAL-R : ANOMALOUS VALENCY. I27magnetic moments of cerium and praseodymium metals have alsobeen measured by a group of Russian workers l1 and found to be11.1 and 16.1 Weiss magnetons, respectively. I n these units thetheoretical values for Ce3+ and Pr3+ are 12-6 and 17.9, respectively,so the above-mentioned data are confirmed. The results forlanthanum, cerium, and neodymium are also confirmed by the workof F. Trombe,12 who obtained a value of 1’7.8 Weiss magnetons forpaf. of neodymium metal, compared with the theoretical value forNd3+ of 18.0.In this group, owing to the occurrenceof ferromagnetism to a greater or less extent, it is better to consider,not pd., but the pmamagnetic moment calculated according toPLpara.= 2.841/xat. (T - O), where 0 is the Curie temperature.Details concerning the ferromagnetic behaviour of this group willbe found in Klemm and Bommer’s paper. It is sufficient to statehere that gadolinium is the only metal of the series which manifeststhe complete beliaviour of a ferromagnetic substance, and thisobservation is confirmed by Trombe. In Table 111, Klemm andBornmer’s values of ppara, and palc. (Bob magnetons) are shown.(2) Europium-lutecium.TABLE 111.P m .EU ..................... 8.3Gd ..................... 7.8Tb ..................... (9.0)Dy .....................10.9’Ho - .....................Er ..................... 9.5Tm ..................... 7-6Yb ..................... 0Lu ..................... 0r-- M4-+.1.53.47.99.710.610.69.67.64.5pI2aJc.eM 3 - k . M2+.3.4 7.97.9 9.79.7 10.610.6 10.610.6 9.69.6 7.67-6 4.54.5 0J\0 SOFor the elements gadolinium, erbium, thulium, and lutecium theva,lues of bma agree well with those of pcalc. for M3+, and showthat only normal ions are present in those metals. With dysprosiumthe result indicates that M2+ ions might also be present, but as inthe above-mentioned case of neodymium, this possibility is excludedfrom consideration of the atomic-volume curve and of chemicalbehaviour. The magnetic data for europium and ytterbium showthat M2+ ions preponderate in these metals, and the proportion ofM3+ probably does not exceed 2 or 3%.For gadolinium metalTrombe has obtained a value for p of 39-28 Weiss magnetonscompared with a theoretical value of 39.26.11 L. F. Vereschtschagin, L. V. Schubnikov, and B. C. Lawrev, PhysikaE.2. Sovietunion, 1936, 10, 618.18 Ann. Phyaique, 1937, [xi], 7, 386128 INORGANIC CHEMISTRY.The results of the atomic-volume and magnetio-susceptibilitymeasurements do not provide any indication of a tendency to formanomalous valency compounds amongst the rare-earth elementsother than cerium, praseodymium, and terbium on the one handand samarium, europium, and ytterbium on the other. W. Noddackand A. Brukl13 have attempted to get evidence for the lowervalency state in the case of other elements from measurements ofthe current-cathode potential curves during the electrolysis ofsolutions of the normal ions, using a dropping-mercury cathodeand a large stationary mercury anode.In the case of Sm3+, Eu3+and Yb3+, from which bivalent compounds can be obtained byelectrolytic reduction, the curves show two distinct reductionstages corresponding to H3f -> M2+ and M2+ -T M (amalgam).The differences in the characteristic potentials of the two stages forthe three elements are 14300, 0.575, and 0.290 volt, respectively.The curves of all the other rare-earth ions also show breaks whichindicate two reduction stages, but the differences in the characteristicpotentials are much less than for the three elements just mentioned,in most cases about 0.1 volt or less.With Sc3+ and Gd3+, however,the differences are 0.160 and 0-145 volt, respectively, and Noddackand Brukl suggest, therefore, that salts of these two elements might,under suitable conditions, be prepared in the bivalent form. Theydo not consider that the results can be attributed to impurities,since the materials used were in most cases X-ray spectroscopicallypure, i.e., contained not more than 0.05% of any other rare-earthor disturbing impurity. It should be noted, however, that thulium,which is the most likely element after samarium, europium, andytterbium to form bivalent compounds, gives a difference betweenthe two reduction potentials of only 0.08 volt. Moreover, thereactions of scandium at the dropping-mercury cathode have beenstudied in detail by R.H. Leach and H. Terrey,l4 who found noevidence for the lower-valency Sc2+ ion.H. T.0. J. W.3. PREPARATION OF PURE COMPOUNDS AND METHODS OFSEPARATING RARE EARTHS.Several papers on the preparation of pure bivalent compounds ofsamarium, europium, and ytterbium have been published duringthe last two years. Work of this kind has an important practicalapplication, since the utilisation of anomalous valencies renderspossible rare-earth separation methods, which have many advantages13 Angew. Chem., 1937, 50, 362. l4 Trans. Faraday SOC., 1937, 33, 480TERREY AND WALKER : PREPARATION O F PURE COMPOUNDS. 1%over the more classical methods of fractional crystallisation andprecipitation.It may be recalled that, in general, four methodshave been used in the preparation of bivalent from the normaltervalent compounds, via, (1) the high-temperature reduction ofthe anhydrous trihalides with hydrogen or ammonia, (2) thethermal decomposition of the tri-iodides, (3) the electrolyticreduction of the tervalent ion in presence of sulphate ion, withconsequent precipitation of the sparingly soluble bivalent sulphate,and (4) the reduction of the tervalent ions by metals such as zincin a reductor.The instability of Sm2 + compounds makes their preparation moredifficult than that of Eu2+ and Yb2+ compounds. F. D. S. Butementand H. Terrey l5 have described a modification of the method ofC. Matignon and E.Cazes 16 for preparing anhydrous samarouschloride by means of the high-temperature reduction of the tri-chloride with hydrogen.W. Kapfenberger l7 has made a further study of L. F. Yntema’smethod l8 of separating europium from other rare-earth elementsby electrolytic reduction of a solution of the trichloride at a mercurycathode in presence of sulphuric acid. Btarting with a 3%europium material, containing mostly gadolinium and samariumand traces of terbium, a 98% europium product was obtained afterthree electrolyses. It is claimed that after one or two furtherelectrolyses an X-ray spectroscopically pure product (< 0.1 yoimpurities) can be obtained.An improved method of purifying europium has been describedby H. N. McCoy.lg The starting material is partly purified byelectrolytic reduction, followed by precipitation of europoussulphate, which is then converted into the trichloride and reducedby the zinc reductor method20 to europous chloride.The finaland complete separation depends on the fact that a concentratedsolution of the latter, containing up to 30% of other rare-earthchlorides, gives with concentrated hydrochloric acid a crystallineprecipitate of EuC1,,2H20, which is practically free from otherrare-earth elements. A few further precipitations render thematerial spectroscopically pure, as shown by both its absorptionand its emission spectra. The crystals of EuC1,,2H20, which arerapidly oxidised on exposure to air, could not be distinguished underthe microscope from those of BaC1,,2H20, which are similarlyprecipitated by concentrated hydrochloric acid, and the twohydrates are probably isomorphous.An X-ray examination byl5 J., 1937, 1112.1 7 2. anal. Chem., 1936, 105, 199.l9 Ibid., 1937, 59, 1131.l6 Comnpt. rend., 1906, 142, 83.l8 J. Arner. Chem. SOC., 1930, 52, 2782.2O H. N. McCoy, ibid., 1936, 58, 1577, 2278.REP.-VOL. XXXIV. 130 INORGAXIC CHEMISTRY.L. Pauling21 has established the isomorphism of europuus andbarium sulphates, and therefore also of strontium sulphate.The electrolytic preparation of ytterbous sulphate has beenfurther investigated by J. K. Marsh 22 and by A. BruldZ3 Hithertothis salt has been prepared by reduction at a mercury cathode, andonly in small quantities. Marsh states that electrodes ofamalgamated lead are more conveaient and may be employedsuccessfully in cells of low resistance.The purity of the lead isvery important, and the freedom of the electrolyte from heavymetals is a factor on which the stability of the reduced salt islargely dependent. Further reduction is very slow when theYb,O, content of the solution falls to 10-15 g./l. This representsa 95 o/o efficiency, with a concentrated sulphate solution initially,and marks the usual limit to which it is worth working. In fourprecipitations the purity of the sulphate can be raised to -iOOyo.Ytterbium acetate undergoes ready reduction in presence of aceticacid when treated with sodium amalgam, and addition of sulphateion then gives a precipitate.Owing to the difficulties in recoveringthe rare earth in presence of much sodium, it is doubtful whetherthis method of reduction can compete in utility with the electrolyticone, which Marsh has used to obtain 95% lutecia from ytterbiurn-lutecium mixtures.Brukl has considerably improved the electrolytic preparation ofytterbous sulphate at a mercury cathode by using an electrolytecontaining sulphuric acid. Starting with a material containing a tleast 96% of ytterbia, he obtained a very pure product by a singleelectrolysis, and from a mixture with lutecium containing about66% of ytterbium a single electrolysis gives 98 % ytterbous sulphate.The mother-liquor can be electrolysed further after the addition offreshly precipitated strontium sulphate, on which the isomorphousytterbous salt is deposited.This method is stated to be veryeffective for the removal of ytterbium from its mixtures withthulium and lutecium, such as are obtained in the fractionation ofthe yttrium earths. Brukl has also applied the electrolyticreduction of ytterbic salts as a method for the quantitativedetermination of the metal. The reduced ytterbous solution isoxidised with ferric alum, and the ferrous ion produced titratedwith permanganate.The earliest rare-earth separation method utilising the anomalousvalency of an element was that in which cerium is separatedeffectively from its neighbours in one step by oxidation to the ceric21 J . Amer. Chern. Xoc., 1937, 59, 1132.22 J., 1937, 1367.23 Angew. Chenz., 1937, 50, 26TERREY AND WALKER : PREPARATION OF PURE COMPOUNDS.131state. J. A. C. Bowles and H. M. Partridge24 describe a methodwhereby a satisfactory separation of ceric cerium and lanthanumcan be obtained by fractional precipitation of the sulphates. Themethod is based on measurements with the glajss electrode of thep , at which the various rare-earth sulphates are precipitated fromsolution on the addition of sodium hydroxide. I n the case of cerica.nd lanthanum sulphates the p , necessary for precipitation (5.78and 7.62, respectively) differs sufficiently to make possible analmost quantitative separation of Ce(SO,), from La,(SO,),. Ii'orthe precipitation of the normal tervalent sulphates there is a totalpE diEerence of only 1-46 between lanthanum and ytterbium, sothat, in general, separation of the rare-earths by this method isimpracticable.I n conclusion, reference may be made to the absorption spectraof non-tervalent rare-earth corn pound^.^^ Those of solutions ofthe tervalent ions have been much investigated, but the origin ofcolour in the rare-earth compounds is a complicated problem whichis as yet incompletely solved.It is known that the 4f electrons,which are responsible for the paramagnetism, are also responsiblefor the colour, and it might be expected that ions with the samenumber of 4f electrons would show similar absorption spectra andhence similar colours. Very few data are available, however, onthe absorption spectra of non-tervalent rare-earth ions. F.D. S.Butement and H. Terrey l5 have investigated the absorptionspectra of Eu3+ and 5m2+ from the point of view of their iso-electronic structure and find that the spectra of pink solutions ofEuCI, and of red solutions of SmCl, show a general similarity withregard to the wave-lengths of the chief absorption maxima. Thesimilarity is not complete, for whereas the bands of Eu3+ show theextremely narrow appearance characteristic of many rare-earthbands in the visible region, those of Sm2+ are among the broadestshown by any rare-earth compound. Comparison of the absorptionspectrum of samarous chloride solutions with that of samaricchloride solutions 26 shows that the shift of the valency electron inSm3f Sm2f is responsible for a profound change in theabsorption.Similarly, H. N. McCoy2' has shown that theabsorption spectrum of a solution of europous chloride in the visiblerange is quite different from that of the europic salt. The solutionof the former (20-30%) has a greenish-yellow colour like that of aconcentrated solution of chlorine. It does not show any of the24 I n d . Eng. Chem. (Anal), 1937, 9, 124.25 Cf. Pearce and Selwood, Zoc. cit., ref. ( l ) , p. 227.z 6 W. Prandtl and K. Scheiner, Z. anorg. Chem., 1934, 220, 107.27 J . Amer. Chem. SOC., 1936, 58, 1580132 INORGANIC CHEMISTRY.absorption bands of the trichloride in the visible region, but absorbscompletely below about 4480 A. There is a rough similarity withthe absorption spectrum of GdC1,,26 which also shows no bands inthe visible region, but in this case it appears that appreciableabsorption commences only in the ultra-violet region a t about3 0 0 0 ~ .A more detailed study of the absorption spectra of therare-earth ions which have an iso-electronic arrangement would beof considerable interest.H. T.0. 5. W.4. THE LOWER OXY-ACIDS OF BORON.A. Stock and E. Kuss observed that when either of the hydridesof boron, B2H6 or B4H,,, was allowed to act on a concentratedpotassium hydroxide solution a salt of the empirical formulaKOBH, was formed :B,H,, $- 4KOH -+ 4KOBHz + H2This salt possessed marked reducing properties and was only stablein the presence of strong alkali. In more nearly neutral solution itunderwent decomposition, hydrogen being evolved and metaborateremaining :2HOBH, + 2H20 --+ 2HB0, + 5H2Shortly afterwards, M.W. Travers, R. C. Ray, and N. M. Guptafound that when magnesium boride (prepared by heating to redness1 part of boric anhydride and 2$ parts of magnesium powder) wastreated with water, hydrogen containing only traces of boronhydrides was. given off, and that the resulting solution actedtowards organic and inorganic compounds as a powerful reducingagent. It had the property of evolving hydrogen on treatmentwith acids, and after acid treatment it would react with iodine.The original solution was not very stable in the air, absorbingoxygen and forming metaborate. They concluded from a study ofthe solution-the volume of hydrogen evolved and amount ofiodine taken up-that it contained the compound H,B,O,.Whensolutions were kept in sealed tubes, particularly after ammonia hadbeen added, a change took place involving an increase in thequantity of hydrogen evolved on addition of acids, and theysuggested that two isomeric compounds, which they denoted asH4 H2B202 and H2 H4B202, were present. They were at that timeunable to isolate from their solutions any definite solid product.1 Ber., 1914, 47, 3115.“Some Compounds of Boron, Oxygen and Hydrogen,” H. K. Lewis& co., 1916TERREY : THE LOWER OXY-ACIDS OF BORON. 133Later, R. C. Ray3 described the isolation of the potassium saltof one of the above acids. The magnesium boride was treatedwith dilute (N/lQQ) potassium hydroxide until the magnesium wasprecipitated ; this was filtered off, and the solution fractionallycrystallised.The first fractions consisted of metaborate andmagnesium hydroxide ; on further concentration, a crystalline solidseparated which could be recrystallised from water freed fromcarbon dioxide. The crystals, probably belonging to the cubicsystem, were slightly deliquescent and readily soluble in water.In the dry state they were quite stable, but evolved hydrogenslowly on exposure to air. Aqueous solutions behaved in theirreducing properties like the original magnesium solutions. Treat -ment with acids brought about decomposition with hydrogenevolution, and the resulting solution absorbed iodine. The atomicratio of the hydrogen given off to the iodine taken up was foundto be 2.From theequivalent conductivity of solutions it was concluded that twoatoms of boron were present in the molecule, and that the aboveformula should be doubled, i e ., K,02B,H4. The reactions withacid and iodine were expressed as follows :Analysis showed that the compound was KOBH,.H,B,(OK), + 2H2SO4 --+ BKHSO, + B,(OH), + 2HZB,(OH), + I, + B,O, + 2HI.It should be noted that the product obtained after oxidation withiodine is diboron dioxide and not the typical oxide of boron.As mentioned above, the possibility of an isomeric form of thissalt was indicated by Travers. This second form has now beenisolated by Ray.4 Magnesium boride was prepared as before, butprior to the treatment with alkali, 2% of magnesium powder andISYO of boric acid were added. The middle fraction of thecrystallised solution was fractionally recrystallised, leading to theseparation of two compounds-a dipotassium salt p-K,H,B,O,isomeric with the one earlier prepared, and a dipotassium saltK,H,0,B2, derived from another acid H4B20,.Treatment of thefirst salt with dilute potassium hydroxide resulted in the formationof a tetrapotassium salt, K4H,B,0,. This could also be obtainedby treatment of the cooled magnesium boride mass with ratherstronger alkali (N/ZQ) than was used in the earlier case. All thesecompounds are strong reducing agents and from molecular-weightand conductivity measurements seem to contain two atoms ofboron. The derivative from the acid H,B,O, differs from theothers in that no hydrogen is evolved on treatment with acid.J ., 1922,121, 1088. * Trans. Paraday SOC., 1937, 33, 1260134 INORGANIC CHEMISTRY.Ray has suggested the following structures for the isomericcompounds :[ H ~ ~ B - O H - H+ H*-B**OH - 13+1 H-B-OH J - H+ HO**B*-H -H+and [ :: 3a - Compound. b-Compound.These are cis- and transforms, the double bond implying inabilityof the boron atoms to rot,ate. They can lose two or four atoms ofhydrogen. In the case of the a-compound it is considered that theadditional two atoms of hydrogen can be more easily lost giving (I),B**OH H * B OH H B OH .. . ..R * * O H H B OH OH i: H(1.) (11.) (I11 .)but with the p-compound the loss of two atoms of hydrogen wouldlead to either (11) or (111), and since the double bond has beenremoved, these are identical.By the loss of two atoms of hydrogenthe a-compound should give a similar derivative, but this has notbeen experimentally realised.Another lower boric acid of the formula M,B,O, has been recentlyisolated by E. Wiberg and W. Ru~chrnann.~ When a boric esteracts on boron trichloride, a chloroboric ester is formed :BCI, + .ZB(OR)3 + 3B(OR),ClThe latter esters on treatment with pure sodium amalgam in thecomplete absence of water undergo reduction, with formation ofesters of the type B,(OR),. Hydrolysis of these in a vacuum(complete absence of air) with water results in the liberation of thecorresponding acid, which is obtained in the form of a white solid :B,(OR), + 4HOH -+ B,(OH), + 4ROHLike the other acids, it is a powerful reducing agent.presence of water, hydrogen is evolved and boric acid formed :In theB,(OH)4 + 2HOH + 2B(OH), + H,The solutions are stabilised by acids and alkalis ; e.g., in the presenceof B~-acid or -alkali a solution of the acid of the same concentrationwas scarcely affected by exposure to the air for 4 hours.Solutionsof silver nitrate and potassium permanganate are readily reduced,but the acid is not oxidised by iodine.This acid is apparently derived from the oxide B,O,, which wasti Ber., 1937, 70, 1303TERREY : THE LOWER OXY-ACIDS OF BORON. 135recognised by Travers and his co-workers,2 who obtained it byoxidising H2B202 with iodine. It has also been identified in anumber of other reactions. For instance, it is formed in thefollowing hydrolyses :(1) B2C14 + 2H,O 4 B202 + 4HC1In this reaction no hydrogen is evolved.6(2) BzHsK, + 4H2O + B202 + 6H2 + 2KOHHere on hydrolysis with alkalis only six molecules of hydrogen areevolved,This reaction is realised when the ammonium salt of B4H10, i.e.,(NH4),[B4H,] is treated with hydrochloric acid and the resultingproduct hydrolysed; only 9 molecules of hydrogen are evolved,whereas for completz oxidation to boric acid 11 molecules shouldbeFor an unsaturated oxide it is apparently extremely stable,especially in the presence of acids or alkalis.In acid solution it isunaffected by iodine, and in the presence of lime it can be heatedin the air without undergoing complete oxidation. On the otherhand, mere exposure of the oxide itself to the air results in theformation of boric acid.These lower boric acids can all be considered to be formed by thehydrolysis of B4H10 :(3) B4K10 + 4H20 -+ 25,02 + 9H2U) 2B4HI3 + 8H20 -+ 4B2MdOH), + 2H2(2) B,HlO + 4H,O -+ 2H4B2(OH), (two forms) + 3H,(3) B&l0 + 4H20 + 2B2(W2 + 7H2(4) B4H1, + 8 H 2 0 2B2(0H)4 9H2although this has only been experimentally carried out in the casesof (1) and (4)-in (4) B20, is actually formed.Interconversion isonly possible in the cases of (2) and (3), although in these, oxidationwith iodine leads to B202, the oxide from which (4) is derived.Stability seems to decrease in passing from (1) to (4) : B,H,(OH),is certainly the most unstable, and B2(OH), is the only one so farisolated in the solid state.H.T.A. Stock, A. Brandt, and H. Fischer, Ber., 1925, 58, 643.A. Stock, W. Sutterlin, and F. Kurzen, %. unorg. Chem., 1935, 225, 225.8 A. Stock, E. Wiberg, and H. Martini, Ber., 1930, 68, 2927136 INORGANIC CHEMISTRY.5. RECENT WORK ON THE OXIDES OF THE HALOGENS.By passing a mixture of oxygen and fluorine at a pressure of10-15 mm. through an ozoniser cooled in liquid air, 0. Ruff andW. Menzel1 obtained an oxide of fluorine F20,. This oxide can beobtained in the form of orange-coloured crystals which melt a t- 160" to a cherry-red liquid, and this can be distilled a t lowtemperatures, Le., below - loo", without decomposition, but a thigher temperatures the characteristic brown colour of the vapoursdisappears and there is formed first an oxide F O which subsequentlya t still higher temperatures breaks down into oxygen and fluorine.The change F,O, --+ 2F0 took place in an irreversible manner,but the amounts of the two gases present in a mixture startingfroni P20, were dependent on the temperature ; e.g., at - 94" thegaseous mixture consisted of 98.6% F20, + 1.4% PO, but a t - 52"complete conversion into FO had taken place.The boiling andthe freezing point of the second oxide were - 185" and - 223"respectively. Its presence as an intermediate phase in thedecomposition was deduced from the fact that the mixturecontaining F,O, and its decomposition products was completelyabsorbed by hydriodic acid, which was considered not to be feasibleif it were a mixture of oxygen and fluorine.Although vapour-density measurements of the gas were carried out and the oxidisingvalue determined, it is obvious that neither would distinguishbetween 2F0 and a mixture F2 and 0,.Two papers dealing with the thermal decomposition of F,O, haverecently been published by P. Frisch and H. J. Schumacher,2 whofollowed two lines of attack. The rate of decomposition between- 25" and - 60" was found to be homogeneous, and could berepresented by an equation of the typeCF2021 d[Bj 0 2 2 = 1012.4 x 10-17.00/457T -Such an equation could not represent the course of the reaction if itoccurred in stages, as suggested by Ruff, but indicated that directdecomposition to fluorine and oxygen took place. This wasconfirmed by examination of the absorption spectrum, vapourpressures, boiling and freezing points, and action on hydriodic acidsolutions, all of which agreed with the properties of an equimolecularmixture of oxygen and fluorine, and these authors conclude thatF O has no real existence.From the time of N.A. E. Millon in 1843, numerous observers haveclaimed to have made chlorous anhydride, CI2O,, by the action of2;. anorg. Chem., 1933, 211, 204.Ibid., 1936, 229, 423; 2. physikal. Chem., 1936, B, 84, 322TERREY : RECENT WORK ON OXIDES OF THE HALOGENS. 137some reducing agent on chloric acid. Millon3 himself used amixture of arsenious acid and dilute nitric acid, J. Schie14 usedsucrose, L. Carius benzene, and M. Hermann naphthalene.Early examination of the absorption spectrum of this oxide showedit to be identical with that of chlorine d i ~ x i d e .~ . ~ The existenceof two different compounds with the same absorption spectrumwas questioned by A. Sch~ster,~ and closer investigation of theso-called Cl,O, has shown that in general a mixture of chlorinedioxide, chlorine, and often a little carbon dioxide comprised thegas under examination, thus vindicating the use of absorptionspectra for identification purposes,The same fate has befallen the last recommended reducing agent-undecenoic acid. M. Kantzer 10 considered he had proved theexistence of this oxide by allowing sulphuric acid to react withpotassium chlorate in the presence of the above acid. From a studyof the absorption spectrum of the gas so prepared, C.F. Goodeveand F. D. Richardson l1 have shown that again the product is thedioxide.By the action of sunlight on chlorine dioxide cooled below 20°,Millon obtained a red liquid which decomposed in the dark athigher temperatures. A similar liquid was prepared by E. J.Bowen,12 who later showed that on continued illumination it wasconverted into colourless dichlorine heptoxide, Cl,07. From aconsideration of its properties he concluded that it differed fromany of the known oxides of chlorine. By analysis of the red liquidM. Bodenstein, P. Harteck, and E. Padelt,13 showed that theoxygen : chlorine ratio was 3 : 1, and from determinations ofthe molecular weight from measurements of the depression of thefreezing point of carbon tetrachloride, concluded that in thedissolved state the oxide had the formula Cl,06. Further work l4on this oxide has shown that in the vapour phase it exists in themonomeric form, but from magnetic measurzments it was concludedthat an equilibrium between the two forms existed in the liquidand the solid state.15 In the latest paper l6 the purification of thecompound is further described. It is shown that, not only is it3 Ann.Chim. Phys., 1843, 7, 298.5 Ibid., 1867, 140, 317. 6 Ibid., 1869, 151, 63.7 W, A. Miller, Phil. Mag., 1845, 27, 81.8 I ) . Gernez, Compt. rend., 1873, 74, 660.9 Rep. Brit. ASSOC., 1880, 258.11 Ibid., 1937, 205, 416.1s 2. anorg. Chem., 1925, 147, 233.14 C. F. Goodeve and F. A. Todd, Nature, 1933,132, 514.15 J.Farquharson, C. F. Goodeve, and F. D. Richardson, Trans. Baruduy18 C. F. Goodeve and F. I). Richardson, J., 1937, 294.Annalen, 1858, 108, 128.lo Compt. rend., 1936, 202, 209.l2 J . , 1923, 123, 2328; 1925,127, ,510.SOC., 1936, 32, 790138 INORGANIC CHEMISTBY.necessary to distil away the more volatile fractions, but owing tothe presence of a non-volatile residue, possibly produced by theaction of the reagents on the glass, it is essential to distil thehexoxide before determining its physical properties. The meltingpoint measured in quartz sampling tubes mas found to be3.50"&0-05", a value much higher than that previously recorded.The vapour pressure was measured over the range - 40" to + ZOO,and it was found that the values for the liquid and the solid lay ontwo straight lines which could by expressed by the followingequationsLiquid : loglopm.-- - 2070/17 + 7.1Solid : log,,p,,,, = - 2690/T + 9.3Calculation of the latent heats of evaporation and sublimation gavevalues of 9-5& 1 and 12-3&0-5 kg.-cals. per g.-mol., respectively.These values are much higher than those of any of the other oxidesof chlorine. This is coupled with the highest melting point andhighest density. Goodeve has suggested that these values,especially when compared with the heptoxide, can be accounted foron the assumption of a symmetrical non-planar structure (I) for/*\ O\ - /O 0 c1 c1-0 7 clG O ? 0 1'0(I.) Non-planar symmetrical, Cl,O,. (11.) Non-planar unsymmetrical, ClzO,.this oxide and an unsymmetrical one (11) for the heptoxide.Thesymmetry of Dhe hexoxide permits the more ready formation ofcrystals in which the molecules can pack more closely together.In 1930 E. Zintl and G. Reinicker l 7 showed that when brominewas passed over specially active mercuric oxide the issuing gascontained a small amount (about 4%) of an oxide which proved onanalysis to be Br,O. W. Brenschede and H. J. Schumacher18failed to isolate the gas in this way, but obtained it in concen-trations greater than 50% of the total bromine taken by theaddition of mercuric oxide to bromine dissolved in carbon tetra-chloride. The reaction was considered to occur through theintermediate formation of mercuric oxybromide :HgO + Br,+ RgOBr,HgOBr, + Br,+ HgBr, + Br,OEvidence for the entity of the oxide and for its molecular state wasobtained from its absorption spectrum, and cryoscopically.Itssolution in carbon tetrachloride was stable below - 20" in the darkl5 Ber., 1930, 83, 1098. l8 2. anorg. Chem., 1936, 226, 370TERREP : RECENT WORK ON OXIDES OF THE HALOGENS. 139but decomposed a t room temperature, producing oxygen, carbonylchloride, chlorine, and bromine.hadpreviously found that (Br,O& was formed as a white crystallinesolid by the action of ozone on bromine. It is only stable a t lowtemperatures, and possibly exists in two modifications with atransition temperature a t - 35".R. Schwarz and M. Schmeisser20 have now succeeded inisolating another oxide of bromine, BrO,. This can be preparedwith a yield of 80% calculated on the bromine used by the passageof a 1 : 5 mixture of bromine and oxygen through a U-shapedozoniser furnished with aluminium electrodes, the greater part ofwhich was immersed in liquid air.A favourable yield dependedon the design of the ozoniser and on the temperature. No oxidecould be detected when the gases were allowed to flow into theuncooled ozoniser and then subsequently passed through a coolingbath. If the oxygen content of the mixture was not too high theformation of ozone was practically nil, although any formed couldbe removed by fractionation, and excess of bromine could bepumped off at - 30". The oxide was obtained in the form of anegg-yellow-coloured solid. It has no definite melting point, butdecomposes spontaneously a t about 0" into oxygen and bromine.This decomposition was utilised in its analysis, the oxygen evolvedbeing measured, and the bromine determined iodometrically.Nothing is yet known about its molecular state.It was noted that if the oxide was cautiously warmed, thedecomposition seemed to take place through an intermediatestage. Together with elementary bromine, a dark brown and awhite substance were formed.The nature of these is the subjectof further investigation.J. I. 0. Masson21 has made some very interesting observationson the mode of formation of the lower oxides of iodine, which arelikely to lead to a complete elucidation of the structure of thesecompounds. The original method of preparation, due again toMillon, was t o heat iodic acid or iodine pentoxide with concentratedsulphuric acid until iodine simultaneously boils off with oxygen.According to conditions, basic iodous iodate OKIO, (iodine dioxide)or iodous sulphate (IO),S04,9H,0 (P.Chrktien's sulphate 2 z ) canseparate out.,, These products arise from the thermal decom-position of the pentoxide, which takes place in stnges :I n addition to this oxide, B. Lewis and H. J. Schumacher1205 _3 1 2 0 3 + 0, L3 I, + 240,19 2. physikal. Chern., 1928, A, 138, 462.21 Natwe, 1937, 139, 150.23 Cf., however, Ann. Reports, 1935, 32, 159.2o Ber., 1937, 70, 1163.22 See Contpt. rend., 1896, 123, 814140 INORGANIC CHEMISTEY.The iodine sesquioxide formed possesses basic properties 24 andcan unite with the sulphuric acid present, to form the sulphate, orwith iodic acid, giving initially iodate which undergoes hydrolysiswith the formation of the more insoluble basic salt.Masson hasshown that the decomposition of the pentoxide can be arrestedexactly a t the middle stage by using fuming sulphuric instead ofthe concentrated acid, such acid being strong enough to stabilisecationic tervalent iodine even a t 220".Of greater importance is the realisation by him that the reactionis a reversible equilibrium. It is displaced to the left by water togive the stable iodate ion, and to the right by acids sufficientlystrong to convert 1,03 into a salt. Thus the sulphate can beobtained in a quantitative yield by the action of concentratedsulphuric on a mixture of iodine and the pentoxide, the compoundseparating in a pure yellow form.The reaction goes through anintermediate stage, shown by the formation of a very deep brownsolute which, it is suggested, is the sulphate of the tervalent radicalI,+.H. T.6. POLYMORPHISM OF ELEMENTS AND INORGANIC COMPOUNDSAT HIGH PRESSURES.I n 1935, P. W. Bridgman 1 described his redesigned apparatusby means of which substances can be subjected to pressures up to50,000 kg./cm.,2 and reported results obtained with a number ofelements. He has now2 described the effects of high pressure onabout 90 inorganic compounds over a temperature range of - 79"(solid carbon dioxide) up to + 200". In his initial work Bridgmanwas limited to pressures of the order of 12,000 kg./cm.2 owing tothe bursting of the containing cylinders.This difficulty wasovercome by making the external walls of the cylinder cone-shapedand supporting this in an external sleeve. Application of pressureon the piston forces the cylinder with an equal pressure into thesleeve so that the external pressure on the cylinder keeps pace withthe internal. The cylinder was constructed of " solar," i.e., awater-hardening silicon-manganese steel, and the piston (whichwas about 6 mm. in diameter) of " carboloy " t h e cementedcarbide of tungsten and cobalt. Temperature control was attainedby means of a bath fixed to the sleeve. For low temperatures,24 Cf. F. Fichter and H. Kappeler, 2. anorg. Chent., 1915, 91, 134.Physical Rev., 1935, 48, 893.Proc.Nut. Acad. Sci., 1937, 23, 202; Proc. Arner. Acad., July 1937TERREY : POLYMORPHISM OF ELEMENTS, ETC. 141solid carbon dioxide, and for higher temperatures, oil electricallyheated, were used, the temperature being measured by a thermo-couple; 200" was about the maximum temperature attainable a thigh pressures owing to the softening of the steel. As in the earlierwork, the pressure was determined from that in the press and thearea of the piston, and the volume change from the movement ofthe piston.For the elements discussed in the 1935 paper, transitions arerecorded in the cases of bismuth (four solid forms 3), thallium (3forms), tellurium (3 forms), gallium (3 forms), and mercury. I nFig. 2 the phase transitions of bismuth are shown, the abscismFIG.2.denoting pressure in kg./cm.,2 and in Table I V the transitionparameters for mercury. I n this case extrapolation of thePress.,kg. /cm.2.10,00015,00020,00025,00030,00035,000TABLE IV.Av, Latent heat,Temp. 104dt/dp. ~rn.~/g x lo6. cal./g.-109" 77 104 0.518- 73 67 71 0.495- 43 57 51 0.483- 17 48 41 0.511+ 5 40 36 0.586 + 23 32 32 0.694temperature-pressure results suggests that the transition should bein the neighbourhood of liquid-air temperatures a t ordinarypressure. This has not been observed, although X-ray spectra,Physical Rev., 1935, 4'7, 427142 INORGANIC CHEMISTRY.have been taken at these temperatures. This may be due to theviscid resistance to transition a t low temperatures.With the following elements no changes were observed : Li, K,Ca, Cd (solid carbon dioxide temperatures), Mg, Ba, In, C (graphite),Ge, Sn, Pb, P (dense black form), As, Sb, S, Se (amorphous andmetallic) (at solid carbon dioxide ar,d higher temperature).A few experiments on alkali halides are also given in this paper.Earlier work had shown that rubidium chloride, bromide, or iodidechanges from the simple cubic sodium chloride structure to thebody-centred cesium chloride structure.This occurred with thepotassium salts at higher pressures, but pressures still higher than50,000 kg.lcm.2 seem requisite for lithium and sodium. Attemperatures below 200" the transition pressures for rubidium andpotassium increase in the order I, Br, C1.This is the reverse of theorder for the corresponding ammonium salts. Above ZOO",however, the transition curves for potassium iodide and bromidecross. The transition parameters for the potassium halides aregiven in Table V.TABLE V.Change ofSalt. kg./cm.2. of vol. dt/dp. cals./g. kg.-cm./g.Fractional Latent internalPress., decrease heat, energy,KC1 ............ 19,900 0.108 +0.200 -1.97 + 1006KBr ......... 19,300 0.102 -0.188 t l . 2 2 680KI ............ 17,850 0.087 +0.430 -0.42 472The fluorides seem different from the other halides. Measure-ments on czsium fluoride, the only czsium halide to crystallise inthe simple sodium chloride system and containing the alkali elementwhich would be expected to show transition at the lowest pressure,showed that it did not undergo any change.Of the 90 inorganic compounds more recently examined, 35 wereshown to exhibit polymorphism.The relevant data for an averagetemperature of about 100" in the case of 10 of these are given inTable VI.Some general observations have been made by the author basedon a statistical study of all his results. Since transitions wereusually observed irrespective of the temperature-the transitionlines passing through the entire temperature range for a pressurechange of 10,000 kg./cm.2 or less-and since a t the absolute zero atransition line must be vertical, it follows that most of the transitionlines will strike the pressure axis at 0" K., and that polymorphismmust be a common phenomenon at the absolute zero,In the earlier work up to 12,000 kg./cm.2 it was found that 14out of the 59 transition linen were of the ice type, i.e., the phasTERREY : POLYMORPHISM OF ELEMENTS, XTC.143Substance .HgCLAgNO,KCNNaClQ,NaBrQ,NaClQ,KIO,CSC10,TlClO,Mean press.,16,6002,20024,00038,50022,5004,40021,20019,00032,20015,00032,00028,00036,00018,90025,30032,50012,8001,70011,900kg.TABLE VI.Mean dtldp.-0.0180-1670.046-0.0940.056-0.0880.0900.0420.005 - 0.046-0.016-0.0100.008 - 0.0270.017 + 0.01 8-0.0130.0740.114-0.125Mean vol.change, yo.0.71.10.61.32.72.98.00.40.40.11.11.53.02.50.43.70.44.92-2Mean latent heat,kg. - em. 18.29.04.58.48.437.085.0220-0360.0197.02.0100.0350.063-0116.030-00%4.648-013-0stable at higher temperatures had the smaller volume.This typeof change is more common a t higher pressures, for 19 cases or 43%were recorded.Another difference found between transitions a t low and a t highpressures was that the internal energy of the higher-pressure formwas greater than that of the lower-pressure form in 78% of thetransitions--the reverse is the case for normal transitions a t lowpressures. Neither the latent heat nor the volume change has anystatistical trend with pressure, so that AE = L - p . A v tends toincrease proportionally to the pressure. This means that thermaleffects become less, and mechanical effects, expressed by p.Av, moreimportant at high pressures.From Schottky's theorem, the total internal kinetic energy underthe experimental conditions is expressed byAEEnetic = 4 p .A ~ - Land L can be neglected in comparison with 4 p . A ~ ; since Av isnegative, the total intlernal kinetic energy decreases on passing fromthe low- to the high-pressure phase. Part of AEkinetic arises froma change in the zero-point energy. If this increases on passing tothe high-pressure form, then the part of AE arising from the internalmotion of the electrons of the atom or molecule must decrease bymore than 4p.Av. On the view that the atoms in the solid have asimilar electronic distribution to that in the isolated state, this mustmean an increase in the size of the atom on passing to the high-pressure form.As Bridgman states : (' This result is so highlyparadoxical that one seems almost driven to the conclusion that a144 lNORGANIC CHEMISTRY.important fraction of the electrons are in an essentially differentstate from that in the free atoms and that polymorphic transitioninvolves an important change in the state of these electrons. Itsuggests itself therefore that the clue to the explanation of thesepolymorphic changes which up to now has so obstinately resistedtheoretical attack is to be found in something similar to theco-operative phenomena between the electrons of the entirestructure which are already known to be determinative forelectrical resistance. ”The same author 4 has investigated the effects of applying ashearing stress simultaneously with the pressure.It might beexpected that transitions which would not occur under anycombination of temperature and hydrostatic pressure might beexhibited under conditions where the shearing stress was verygreatly increased. With the possible exception of lithium, thiswas not found to be the case. Certain observations, however, onthe properties of crystals and glasses are worthy of mention.(a) The shearing stress a t plastic flow of a material has usuallybeen considered to be independent of the pressure. It was found,however, that the shearing strength of a crystal increased withincrease of pressure. With many metals the increase might be asmuch as ten-fold.( b ) Under conditions of great stress and high pressure, it mightbe thought that the crystalline state would break down completely,giving an amorphous mass.This is not so, for the crystalline stateis retained and may even be built up under the severest conditions,e.g., quartz glass tends to crystallise, and transitions were observedjust as they were under pure hydrostatic pressure.( c ) Resistance to plastic flow became greater the more finely thestructure was broken up by continued deformation. Thus acleavage plate of graphite, in which slip easily occurred initially,hardened rapidly on breaking down, and finally became anabrasive, rubbing metal off the hardened steel surfaces of thetesting apparatus. The hoped-for transition from graphite todiamond did not take place.As might be expected, welding of the material was almostgeneral.Under the enormous stresses the molecules are broughtinto the range of each other’s forces, where they attract just as theydo in a solid piece of matter.With certain substances, permanent non-reversible changes indensity were observed, especially where two forms are capable ofexistence. For instance, chalcocite was changed throughout itsmass into cubic cuprous sulphide and calcite became denser, owing* Phpical Rev., 1935, 48, 825; J . Geol., 1936, 44, 663TERREY SOME ELEMENTS AND COMPOUNDS. 145presumably to partial conversion into aragonite. A few changes ofa purely chemical character occurred, these being verified (owing tothe small amounts of material available) by X-ray analysis; e.g.,bismuth oxide was reduced to elementary bismuth, stannic oxidegave stannous oxide, and similar changes almost certainly occurredwith mercury and lead salts.A mixture of copper and sulphur wasconverted into cuprous sulphide, the product being a mixture ofchalcocite and the cubic variety. From the above-mentionedtransformation, this would indicate that chalcocite is the form firstproduced under these conditions.H. T.7. SOME ELEMENTS AND COMPOUNDS.In this section no attempt has been made to give a comprehensivesurvey, and the topics dealt with represent only a fraction of thework carried out during the past year in Inorganic Chemistry.The selection of these topics has been somewhat arbitrary.Although much interesting work has been carried out on molecularstructures,l these have been deliberately omitted, as have alsophase-rule studies and alloy systems.Rare-earth EZeme?zts.-By the action of alkali metal on thecorresponding halide, W.Klemm and H. Bommer have succeededin isolating all the rare-earth metals except holmium, and haveinvestigated their lattice structures and magnetic properties.Prior to this work the only rare-earth elements isolated in therelatively pure state were lanthanum, cerium, praseodymium, andneodyrni~rn,~ and gadolinium.4~ 5 The purity of samarium obtainedby Muthmann, Hofer, and Weiss is open to question, and the publisheddata on erbium seem to indicate thaL a very impure specimen wasbeing used, for the lattice constants 6 found are much greater, andthe magnetic susceptibility very much smaller, than thoserecorded in the present paper.Wohler's method of preparation was selected as the most suitablewhen dealing with small quantities, and as giving a product whichCf.E. G. Cox, A. J. Shorter, W. Wardlaw, and W. J. R. Way, J., 1937,1556; H. D. K. Drew and N. H. Pratt, ibicl., p. 506; H. D. K. Drew andF. W. Chattaway, ibid., p. 947; M. Burawoy, C. S. Gibson, G. C. Hampson,and H. M. Powell, ibid., p. 1690.2. anorg. Chem., 1937, 231, 138.W. Muthmann, H. Hofer, and L. Weiss, Annalen, 1901, 320, 231.G. Urbain, P. Weiss, and F. Trombe, Compt. rend., 1935, 200, 2132.Trombe, Bull. Xoc. chim., 1935, 2, 660.6 J . C. McLennan and R. J. Monkman, Trans. Roy. SOC. Canada, 1929, 23,255.M.Owen, Ann. PhysiE, 1912, 37, 657146 INORGANIC CHEMISTRY.could be used directly for the determination of the more importantphysical properties, the alkali chloride present acting as a calibratingmaterial for the X-ray structure and as a diluent in the magneticmeasurements. The reduction was carried out with liquid alkalimetal which avoided the difficulty experienced by E. Zintl andS. Neumayr,8 who from observafions on the reduction of CeCl, withsodium or potassium vapour and from the behaviour of ceriummetal with potassium vapour concluded Ohat the -rare-earth metaldissolved the alkali element with alteration in the lattice spacing.I n addition to potassium, Klemm and Bommer used rubidium andcmium, since it was felt that these elements with their much widerspacings would not so readily dissolve in the rare-earth element.That this procedure was justified follows from the observations that(a) the spacings obtained were identical irrespective of the alkalimetal used, ( b ) no change was experienced by allowing liquid alkalielement to act on the rare-earth metals, and ( c ) the spacings andmagnetic susceptibilities of the products obtained agreed well withthe better values already recorded in the literature.Difficulty was encountered with samarium, ytterbium, andeuropium, the three elements giving lower chlorides. Here it wasfound that a t high temperatures a back reaction tended to occur :2KC1+ Sa SaC1, + 2K.The best results were obtained withpotassium a t as low a temperature as 250".The purity of the starting product was investigated in every caseeither magnetically or spectroscopically, the estimated impuritiesbeing less than 1% except with Eu (4% Tm), Tm,03(4-7~0 Yb,03and 5.7% Lu203) and Tb, which was an 85% product.Thechlorides were prepared from the oxides by 0. Honigschmid andH. Holch's method,g and the rubidium and cmium by heating thechloride with calcium turnings in an evacuated vessel, followed bydistillation. 10Scandium-Although many attempts have been made to isolatescandium, it is only during the past year that the element has beenobtained in a relatively pure condition. It is somewhat lesspositive l1 than aluminium, but owing to the small amounts of theoxide normally available, electrolytic methods as used for aluminiumare not feasible, and Wohler's method is unsatisfactory owing tothe extraordinary reactivity of scandium and its salts.By usingmolten zinc as cathode and scandium chloride dissolved in theeutectic mixture of potassium and lithium chlorides as electrolyte,2. Elektrochem., 1933, 39, 85.Z . an'org. Chem., 1927, 165, 294; 1928,177, 94.10 Cf. W. Biltz, F. Weibke, and H. Eggers, ibid., 1934, 219, 119.l1 R. H. Leach and M. Terrey, Trans. Faraday SOC., 1937, 33, 480TERREY : SOME ELEMENTS AND COMPOUNDS. 147W. Fischer, K. Brunger, and H. Grieneisen l2 succeeded in isolatinga scandium-zinc alloy from which the zinc and any alkali metalcould be removed by distillation. As a container for the moltenelectrolyte, a magnesite crucible was used.This fitted tightly intoa cylindrical graphite container which acted as anode. Contactwith the molten zinc was obtained by means of a tungsten wirewhich at the temperature of the bath (700-800") was found not toreact with the molten zinc or subsequently formed alloy.The oxide used for the starting material contained small amountsof Zr, Hf, Th, Yb, and Lu. Conversion into the chloride, whichwas attained by heating in a stream of chlorine charged withsulphur monochloride at 1200" and fractionation by volatilisation,gave a still purer product.The alloy resulting from the electrolysis contained 2% ofscandium and about 0.1% of oxide. Unfortunately, in the removalof the zinc this oxide concentrated in the residual scandium, a veryimpure material resulting.This trouble was overcome by filteringthe molten zinc-scandium alloy through a tungsten filter, althoughit reduced the scandium content to about 1%.The element was obtained in the form of a sintered, light greymass, which darkened on exposure; fusion seemed to indicate thatit possessed a silver-white, metallic glance. Analysis showed amet'al content of 94--98y0, the impurity being chiefly oxide whichmay account for its hard and brittle properties. The meltingpoint was found to be approximately 1400" and the density of asample (9S-4y0 Sc) sintered at 1250" was 3-05, which increased to3.08 on fusion.GakZium.-F. Sebba and W. Pugh 13 have described their processfor the preparation of relatively large quantities of pure gallium.The possibility of separating this element by electrolysis has beenrealised since the early work of P.E. Lecoq de Boisbaudran,14 whoobtained it in this way from an alkaline gallate solution. Laterworkers have preferred dilute acid or ammoniacal solutions. Thelatter baths are obviously unsuitable from concentration con-siderations. The use of alkali gallate had been criticised by L. M.Dennis and J. A. Bridgman l5 on the grounds that deposition wasslow a8nd that the metal contained alkali, The authors, however,showed that these criticisms are not valid, current efficiencies of25-30~0 being possible if last traces were not removed, and thatthe metal after being washed was spectroscopically free fromalkali.The greatest difficulty was in the design of a suitable form of12 2.anorg. CJzem., 1937, 231, 54. l3 J., 1937, 1373.14 Bull. SOC. chim., 1879, 31, 50. l5 J . Amer. Chem. Soc., 1921, 43, 274.This value gives an atomic volume of 14.5 C.C148 INORGANIC CHEMISTRY.cathode. From cold solutions the metal separates in the form oftrees with a large surface and a maximum amount of impurities,from a warm solution (above 30") in the form of globules whichdrop off the cathode and, being no longer cathodic, dissolve in theelectrolyte. By using a cathode in the shape of an inverted cup,the metal could be collected in the molten condition and keptcathodic. Platinum, although slightly attacked, was preferred forelectrodes.The gallium so obtained was contaminated by traces of lead, tin,and platinum.These were removed by washing with dilutehydrochloric acid followed by dilute nitric acid, the resulting lossof gallium being only of the order of 5%. The removal of platinumin this way is rather surprising, but only traces of iron could bedetected spectroscopically in a sample of oxide prepared from themetal.Oxides.-(i) I n the AnnuaZ Reports for 1935 l6 am account wasgiven of P. W. Schenk's early investigations on sulphur monoxide.This work has been extended.l7 The formula has been confirmedby a quantitative synthesis from sulphur dioxide and sulphur.The oxide is also formed in the thermal dissociations of thionylchloride at 900°~100 or of thionyl bromide a t 52O"~lO". Atlower temperatures the reverse change takes place, SO unitingreadily with chlorine or bromine.The halogen can be removed a tlower temperatures from the thionyl compounds by means ofmetals such as sodium, tin, magnesium, or aluminium. I n thedecomposition 250 +- SO, + S the sulphur left behind containsappreciable amounts of oxygen. A product of approximatecomposition S20 is formed, which in a vacuum a t 100" gives rise toa mixture of sulphur dioxide and monoxide with a high proportionof the latter and can be used as a suitable source of the gas.Attempts to prepare the corresponding selenium compound SeOhave so far been unsuccessful.l*(ii) Further work has been carried out l9 on the bluish-violetperoxide of phosphorus, PzOs, formed when a mixture of thepentoxide and oxygen is passed through a hot discharge tube, andthe best conditions for its preparation defined.It is insoluble inchloroform, and this fact can be utilised to separate it from thepentoxide. It has been shown that the pentoxide alone whensublimed through the tube gives this oxide, and phosphorusseparates. With water P,06 gives a per-acid, probably H,P20,.It is noteworthy that permonophosphoric acid, H,PO,, originallyprepared by J. Schmidlin and P. &Iassini2* by the action ofl8 Ibid., 1937, 233, 401.2o Ber., 1910, 43, 1162.16 P. 151.lg P. W. Schenk and H. Rehaag, &id., p. 403.l7 2. anorg. Chem., 1936, 229, 305TERREY : SOME ELEMENTS AND COMPOUNDS. 149concentrated hydrogen peroxide on phosphoric oxide, and later byF. Fichter21 by the anodic oxidation of phosphates in potassiumfluoride solution, can easily be prepared by the interaction ofhydrogen peroxide and phosphoric oxide in acetonitriIe solution,yields of 65-68y0 calculated on the oxide content being obtained.22As is well known, this acid is a powerful oxidising agent, convertingmanganous salts into permanganate even in the cold.(iii) I n addition to the two simultaneous reactions in thehomogeneous gas phase already recorded in the case of carbons ~ b o x i d e , ~ ~ vix., polymerisation and the decomposition C,O, -fiCO, + C, a third reaction may also occur, C,O, + 2C+ CsOz,giving rise to a new oxide of carbon, O=C-C=C-C=C=O.This oxide 24 was obtained in a 3% yield during the polymerisationa t 200" of the suboxide prepared from malonic acid.It is describedas a very stable oxide of b. p. 105", as calculated from observationson its vapour pressure a t lower temperatures. It shows no tendencytowards polymerisation ; a t room temperatures it is slowlyconverted into carbon dioxide and an uninvestigated tricarboxylicacid, C,,H1,012. It is interesting t o note that the formation ofthis oxide was never detected in the suboxide arising from diacetyl-tartaric acid. Does this point to a difference in the oxide preparedin the two ways?Early work by electron-diffraction methods indicated that thesuboxide was a linear and symmetrical molecule. This view hasreceived further support from an examination of its ultra-violet,Raman, and infra-red 25 spectra.(iv) A.Guntz and F. Benoit,26 by heating barium with its oxidea t 1150", claim to have prepared Ba20. Their claims were basedon the production of a homogeneous reddish-brown mass and onthe fact that, if any free barium were present, it would, owing toits higher density, sink to the bottom of the melt.* As indirectevidence, they adduced the fact that aluminium reacts energeticallywith baryta, which would not be expected from the known heats offormation of the two oxides, and that reduction of the barium oxideonly proceeded as far as the suboxide stage.The existence of the suboxide is of interest in that oxide cathodes21 Helv. Chim. Acta, 1918, 1, 297.22 G. Toennies, J . Amer. Chem. SOC., 1937, 59, 555.23 A. Klemenc, R. Wechsberg, and G. Wagner, 2.physikal. Chern., 1934,24 Klemenc and Wagner, Ber., 1937, 70, 1880.2 5 R. C. Lord, junr., and N. Wright, J . Chem. Physics, 1937, 5, 642.2 6 Bull. Soc. chim., 1924, 35, 700.* This statement appears to be erroneous : the densities of baryt'a and ofA , 170, 97.the metal at room temperature are 5-39 and 3.63, respectively150 INORGANIC CHEMISTRY.only show a marked electron emission when the ratio Ba : 0 isgreater than unity although this barium excess need not be greaterthan 2-3%.27Reinvestigation of this problem by M. Schrie12* leads fairlydefinitely to the conclusion that this suboxide does not exist.Indirect calculations by Guntz seemed to show that the reactionBaO + Ba + Ba,0 was exothermic to the extent of 15.5 cals.A direct attempt to measure this heat evolution when the twocomponents were heated together failed to indicate any heatchange.The X-ray structure of the product was the same as thatof the original barium oxide, and only a slight change of densitycould be found, which might be expected from the packing ofbarium atoms into the barium oxide lattice owing to its solubilityat high temperatures.The composition of the mass only approximated to that of acompound when the components were taken in the required ratio.Barium oxide is readily soluble in molten barium, and only whenthe ratio Ba : BaO is greater than 2.5 : 1 is the barium at all readilyevolved, even on heating in a vacuum a t 900".(v) Further evidencez9 against the existence of a stable leadsuboxide has been obtained by measurements of the magneticsusceptibility of the product of vacuum decomposition of leadoxalate at 200-300".To compensate for this, a new oxide of lead,Pb,O,,, is said 30 to be formed by the dissociation of the dioxide orthe interaction of lead carbonate and oxygen a t 365-460" underan oxygen pressure of 200 atmospheres.(vi) The formation of titanium monoxide when the dioxide andmetal are heated together in a vacuum has been proved by anexamination of its crystal str~cture.~l It has a melting point of1750", and dissolves in dilute acids with evolution of hydrogen.In connexion with the oxides of titanium, it may be mentionedthat the equilibrium 2Ti0, + H,CTi,O, + H,O has beenmeasured by N. Nasu.3,Boron Hydrides.-By the action of potassium amalgam on thehydrides B,H,, BLfHl0, and B,H9, Stock and his co-workers33prepared a number of borane salts, e.g., B,H, + K2+ K,B,H6.The method used was to shake the hydride for some hours with theamalgam, run off the greater part of the mercury, and distil off the27 T.P. Berdennikowa, Physikal. 2. Sovietunion, 1932, 11, 77.28 2. anorg. Chem., 1937, 231, 313.2B L. We10 and M. Petersen, Physical Rev., 1936, [ii], 49, 864.30 C. Holtermann and P. Laffitte, Compt. rend., 1937, 204, 1813.31 W. Dawihl and K. Schroter, 2. anorg. Chem., 1937, 233, 188.s2 Kinz. no Kenk., 1935, 12, 371 ; Sci. Rep. TGhoku, 1936, 25, 510.a3 2. anorg. Chem., 1935, 225, 225TERREY : SOME ELEMENTS AND COMPOUNDS. 151remainder a t as low a temperature as possible (170-190"), thesalts being left behind in the form of iion-volatile white solids.The salt K2B2H6 could be heated to 300" without change, but a thigher temperatures about one-third sublimed unchanged, theremainder undergoing decomposition :The substance KB2H2, which may be K,B4H4, dissolved in waterwith the evolution of hydrogen.In continuation34 of this work,the corresponding sodium and calcium salts have been prepared,and the properties of the higher members more fully investigated.In each case two equivalents of metal per molecule of hydriderepresented the composition of the salt. At 170" the derivativesfrom B4H,, and B5H, lose hydrogen according to the equationsK,B$&j __t KB&& + K + 2H2K2B4H10 K2B4H8 + HZ2K2B6Hg = K4B10H16 + HZHeated to high temperatures (450"), K,B,HS gave K2B,H,.Allreact in the same way with hydrochloric acid, part forming theoriginal hydride and part being chlorinated to the chloro-hydride.Rontgen photographs of the sublimed potassium salts showed amarked similarity, indicating that they belonged to a series.Unsuccessful attempts were made to prepare KBH, by the actionof atomic hydrogen on &@&6). From Grimm's hydridedisplacement law, [BH,] should act on the one hand as an anionlike [OH]- or [NH2]-, or on the other hand like [NH,]+ or [CH,], sosalts such as k[BH,] should be capable of existence. I n connexionwith active hydrogen, reference should be made to the paper byH. Kroepelin and E. V0ge1,~~ who have investigated the action ofthis gas on nearly 90 inorganic salts.By the action of carbon monoxide under pressure on B2H6,A.B. Burg and H. I. Schlesinger 36 have obtained borine carbonyl :B2H, + 2CO 3 2BH,CO. The molecular s-tate was found fromvapour-density measurements, and it is suggested that thecompound is held together by a co-ordinate link, the electronsarising from the carbon monoxide. An addition compound isformed with ammonia, BH,CO + 2NH, + BH,CO(NH,),.With triethylamine the following reaction takes placeThe last compound is very stable and resists heating at 125" forsome hours. From measurements of the rate of decomposition ofthe carbonyl, it is concluded that BH, has a, transitory existence.In the early days, diborane B,H6 was considered to be akin toBM,CO + (CH3)3N + (CH,)zN,BH, + CQ34 A.Stock and H. Laudenklos, 2. anorg. Chern., 1936, 228, 178.3 5 Ibid., 1936, 229, 1. 36 J. Arner. Chem. SOC., 1937, 59, 780152 INORGANIC CHEMISTRY.ethane. Subsequent research modified this view and tended tolink it up with ethylene. Its unsaturated character was indicatedby its behaviour in liquid ammonia, in which an addition compoundB&,(NH,), is formed, and by the action of alkali metals. Onelectrolysis in ammonia, B,H,(NH,)2 behaves as a salt and isregarded by Stock as [B,H4](NH4), :[B,H41(NH4)2 2 62H4 + 2hH4This leads to the conception of B,H, as an H,[B,H4]. Thebivalent negative radical B2H4 has an ethane-like structure, theboron and carbon in each case being four-covalent. This is morestable than the ethylenic B,H,, which accounts for the stabilityof the metallic boranes.Yurther support for the ethylenic nature of B2H6 is claimed fromparachor measurements 38 [the value 121 -9 harrnonises best with[H,-B = B-H,]--H,' '-, i.e., with two single parachors for 2 boronatoms (2 x 16.4), 4 hydrogen atoms (4 x 17.1), a double link(23.2), and 2 electrovalencies (- 2 x 1.6) = 121.21, from ultra-violetabsorption spectra, dipole, and magnetic measurements.On the conception of the boron hydrides as acids, it is possible tobuild up structures for the two series : B,(H,+4), e.g., B,H&B,H,, etc.; and Bn(HnA6), e.g., B4HI0, B5Hll, etc. The extraelectron required to complete the boron octet and for it to assumea neon-like structure is derived electrovalently from hydrionsoutside the co-ordinate sphere.Recent determinations of the structure of diborane by electrondiffraction 39 are a t variance with any such formuh, and it appearsthat any structure with a double bond between the boron atoms isuntenable. The values obtained for the B-B and the B-Hdistance were 1-86 and 1.27, respectively, and shortening of theB-B bond below the single-bond value was not observed, whichrules out the double bond. The B-H distances are greater thanthe single-bond separations for other diatomic hydrides, so thebonds are weaker than single ones. The distances are compatiblewith structures representing resonance among the seven possiblearrangements,- -H H .. .. H H .. ..H:B:BH H:B B:H etc.H H H Hgiving each 6/7 single and 1/7 zero bond character.37 E. Wiberg, Rer., 1936, 69, 2816.38 A. Stock, E. Wiberg, and W. Mathing, ibid., p. 2811.39 5. H. Bauer, J. Amer. Chem. SOC., 1937, 59, 1096; cf. also Bauer andPauling, ibid., 1936, 58, 2403TERREY : SOME ELEMENTS AND COMPOUNDS. 153Phosphorus Hydrides.-In last year’s Reports 4O doubt wasexpressed with regard to the existence of the higher hydrides ofphosphorus. Further work by P. Royen 41 has confirmed the viewthat these are merely sorption complexes of phosphine and yellowamorphous phosphorus of indefinite composition. The solid“ hydride ” PI2H6, obtained by the decomposition of P,H4, iswithout structure and evolves only phosphine on heating; nohydrogen is given off until the decomposition temperature ofphosphine is reached. The rate of decomposition falls withdecreasing hydrogen content, but no discontinuity is shown a t thesecond solid hydride (P,H2) stage. The desorption is irreversible,although by irradiating white phosphorus and phosphine under30-40 atmospheres’ pressure an amorphous product containing upto 14% of phosphine is formed.With regard to the addition compounds which these hydridesform with piperidine, whence it was deduced that they possessedacidic properties, it is now shown that these also are adsorptioncomplexes. In the addition of piperidine, part of the phosphorusis replaced but there is no stoicheiometric relationship between thephosphorus, hydrogen, and piperidine.I n conclusion, the Reporter feels that the congratulations of allinorganic chemists must be showered on Dr. J. W. Mellor, F.R.S.,on the completion of his stupendous work.42 H. T.H. TERREY.0. J. WALKER.40 Ann. Reports, 1936, 83, 185.4 1 2. anorg. Chem., 1936, 229, 369; cf. I. Mathieson and W. Wrigge, ibid.,42 “ A Comprehensive Treatise on Inorganic and Theoretical Chemistry.”1937,232,284

ISSN:0365-6217    

DOI:10.1039/AR9373400115

出版商:RSC    

年代:1937

数据来源: RSC

摘要:

CRYSTALLOGRAPHY.1. LATTICE DEFECTS IN POLAR CRYSTALS.(a) Electrolytic Conduction in Polur Crystals.THE first theoretical treatment of electrolytic conduction in polarsalts is due to J. Frenke1,l whose ideas have recently been extendedand made more precise in a number of papers by W. Jost,2 W.Schottky,3 and C . Wagner.4 A discussion of these developmentsoccupies the greater part of a recent book by J ~ s t . ~ It is thepurpose of this article to give a brief account of this work.On the experimental side we may refer to summaries by A. vonHevesy6 and A. Smekal.7 The observations on rock salt aretypical of the alkali halides and are illustrated in Fig. 1.It will be seen that below about 600" ( 103/T >1.14) the conductivityis " structure-sensitive," i.e., it depends on the purity and pasthistory of the crystal, but that above 600" it is not structure-sensitive.Similar results follow from the investigations ofW. Lehfeldt 8 on alkali and silver halides.According to Smekal's report,g in the low-temperature region theconductivity is almost entirely due to cations, while in the high-temperature region in rock salt both ions become mobile; he statesthat the observed conductivity may be made up of the sum ofthree terms : (1) A structure-sensitive term representing conductiondue to cations, having the form Ae-B'T, with A of the order 0.8ohm-em., and B - 10,300". (2) A structure-insensitive term,1.4 x lo6 x e-23*G00!T, representing conduction due to cations.(3) A structure-insensitive term, 3.6 x lo6 x e-259700'T, repre-senting conduction due to anions.The theoretical work reported here deals only with the structure-insensitive (high-temperature) conduction.Two mechanisms havebeen proposed :(1) The mechanism of Jost.-According t o Jost, in a crystal in1 2. Physik, 1926, 35, 652.J . Chem. Physics, 1933, 1, 466; 2. physikal. Chem., 1934, A, 169, 129;W. Jost and G. Nehlep, ibid., 1936, B, 32, 1.W. Schottky, ibid., 1936, By 29, 335.C. Wagner and W. Schottky, ibid., 1930, B, 11, 1163." Diffusion und Chemische Reaktion in Festen Stoffen," Dresden, 1937," Handbuch der Physik," 1928, 10. Ibid., 1933, 23, [ii].8. Physik, 1933,85, 717, op. cit., p. 883MOTT : LATTICE DEFECTS IN POLAR CRYSTALS. 155equilibrium at temperature T, a certain number of ions will leavetheir normal lattice positions and migrate to an “ interlatticeFIU. 1.Dependence om temperature of the electrolytic conductivity 04 rock-salt crystals.A@ X Single crystals.o Polycrystalline material.position,” as shown in Pig.2. If E is the work necessary to removean ion from its normal position to an interlattice position, then thefraction of the total number of ions in interlattice positions is shownto be e-*Elkg’. Both cations and anions can move into inter-lattice positions; where, however, the ions are of very differentsizes (e.g., in sodium chloride), only for the smaller ion will E besmall enough to give an appreciable number. In an applied fiel156 CRY RTALLOGRAPHY.the ions which are in interlattice positions will be able to movethrough the lattice; their mobility will be proportional to a factore-vikT, where W is the activation energy necessary to move anion from the centre of the cube in Fig.2 to the centre of a face,which is t'he position of highest potential energy that the ion has toFIG. 2. nIon in interlattice position in sodium chloride structure.pass.will be given by a formula of the typeThus the dependence of conductivity CT on temperature T= Ae-(*E++V)lk* . . . . . . (1)where A is a constant. The vacant lattice points will also bemobile (with a different activation energy), since an ion may moveinto the vacant place from an adjacent lattice point. Eitherprocess may be the more important for the conductivity, dependingon the relative values of the activation energies.(2) The mechanism of Schottky.-According to Schottky, if thetemperature of a crystal be raised, vacant lattice points of eithersign will be formed a t the surface, or at cracks, and travel inwards.Vacant lattice points may thus exist without any ions forcingthemselves into interlattice positions.If Ef, E- are the energiesrequired to remove respectively a positive and a negative ion out ofthe crystal, and Eo the lattice energy per ion pair (and thus theenergy gained if the ions adhere to the surface), then the proportionof vacant lattice points is shown to beexp[- &(Ef f- E- - E,,)/kT] . . . - (2)For a crystal in thermal equilibrium this is, of course, independentof the number of cracks and surface, but the rate a t whichequilibrium is attained will depend on the area of surface fromwhich holes can start.Vacant lattice points of either sign will be mobile, with onlyslightly different activation energies.We thus expect motion oMOTT: LATTICE DEFECTS IN POLAR CRYSTALS. 157ions of both signs in salts where the Schottky mechanism is themore important. At sufficiently high temperatures we also expectan increase in the specific volume, unaccompanied by any increasein the lattice constant.Only rough theoretical calculations of the energies E, W , etc.,have been made a t present.1° Consider, for instance, the quantity+(E+ + E- - * . . (3)which determines the number of vacant lattice points. If only theelectrostatic forces between the ions considered as point chargeswere important, we should haveE+ = E- = E, = 1.74 e2/awhere a is the interionic distance, which gives for (3) an energy ofthe order 4 e.v.for sodium chloride. By taking into account thehigh dielectric constant of these salts, however, Jost has been ableto show that the true value is very much smaller, of the order 1 e.v.In general, a high dielectric constant will lead to a low value of thedissociation and activation energies occurring in these theories.Estimates of the energies involved suggest that conduction inthe alkali halides is mainly due to the Schottky mechanism, thatin the silver halides to the Jost mechanism. This is confirmed bythe fact that conduction by cations and anions is found in thealkali halides.Moreover, measurements by C. Wagner and J.Beyer l1 on the density and lattice constant of silver bromide a t410" show that vacant places in the anion lattice cannot be presentto any extent.The absolute magnitude of the conductivity, and thus theconstant A in (l), has been considered by Jost.12Phenomena, in which vacant lattice points present in a crystal int'hermal equilibrium play a part, are classed by these authors as" Fehlordnungserscheinungen." It may be remarked that if acrystal is cooled rapidly to a temperature at which these latticeholes are no longer mobile, a number will be " frozen in." Arock-salt crystal a t room temperature will normally have a muchlarger number of holes than the equilibrium value a t thattemperature.(b) Colour Centres in Alkali Halides.Transparent crystals may be coloured either by the presence ofcolloidal specks of some foreign substance-as, for instance, silverbromide, which after exposure to light contains colloidal silver-orby the presence of impurities dispersed in atomic form.Anlo Cf. Jost, op. cit., p. 68.l2 Ibid., 1934, A, 169, 129.11 2. physikal. Chem., 1936, B, 32, 113158 CRYSTALLOGRAPHY.example of a crystal coloured by a mechanism of the latter type isyellow rock salt. Coloured alkali halides have been investigated ingreat detail by R. W. Pohl and his co-workers, and also by Smekal.Recently, an hypothesis as to the nature of the colour centres hasbeen advanced by J. H. de Boer l3 which seems to be in agreementwith the observed facts.It is the purpose of this article to presentthe facts which can be explained by this hypothesis. Space doesnot allow any complete summary of the properties of colouredalkali halides; for this, the reader is referred to recent arti~1es.l~The absorption coefficient of coloured alkali halides plottedagainst wave-length shows a characteristic bell-like form. Theabsorbing centres are called in the literature F-centres (Farbzentren).The concentration of P-centres can be obtained from the absorptioncoefficient, values from 1015 to 1019 per cm.3 being obtained.The hypothesis of de Boer is that an P-centre is an electronreplacing a negative ion in the crystal lattice. A point where anegative ion is inissing will behave in a crystal as a positive charge,and therefore be capable of capturing a free electron.The colouris assumed to be due to the absorption spectrum of these trappedelectrons.Colour centres may be formed in the following ways :(i) By illuminating the crystal with X-rays or with certainwave-lengths of the ultra-violet light. Now, we have seen thatan alkali halide crystal at room temperature will normally have anumber of vacant lattice points. On illumination with X-rays, anumber of electrons will be raised from the inner levels of the ionsinto excited levels, where they are free to move about through thecrystal; some of these electrons will be trapped a t points wherenegative ions are missing. Crystals coloured in this way fade withincreasing time, especially a t high temperatures.Electronseventually return to their original positions.(ii) By heating the crystal in the vapour of the alkali metal.The crystal then acquires a stoicheiometric excess of a,lkali metal.The number of colour centres formed is proportional to (at hightemperatures practically equal to) the number of alkali atoms inan equal volume of the vapour.The explanation advanced is that a vacant negative lattice pointis formed a t the surface and traps an electron from an alkali atom.The positive and negative ions so formed adhere to the surface ofthe crystal, thus increasing its volume; the P-centre is mobile a thigh temperatures and travels into the body of the crystal.lS Rec. trav. chim., 1937, 56, 301.l4 R.W. Pohl, Proc. Physical SOC., 1937, 49 (extra part), 3 ; J. H. dc Boer," Electron Emission and Absorption Phenomena," Cambridge, 1936COX : CRYSTAL CHEMISTRY. 169(iii) Alkali halide crystals containing small amounts of alkalihydride show a new absorption band in the ultra-violet, on the longwave-length side of the characteristic band of the halide. Themost simple explanation of this is that H- ions replace the halogenions in the lattice; since the electron affinity of hydrogen is lessthan tha.t of the halogens, less energy will be required to excite anelectron, and the absorption will be shifted to the red.If a crystal is illuminated in this band, F-centres are formed;but the quantum efficiency, ca. lOOyo a t 4Q0°, is only 20% at 0"and falls to zero below - 100".The explanation suggested is asfollows : when a quantum of light is absorbed, an electron is movedfrom the H- ion on to a neighbouring cation. At high temperaturesthe hydrogen atom will then have time to diffuse away, leavingbehind a vacant lattice point and an electron, i.e., an P-centre. Atlow temperatures, however, the diffusion process will not havetime to take place before the electron drops back to its originalposition.N. F. M.2. CRYSTdL CHEMISTRY.A notable addition to the literature of crystal chemistry is'' Atomic Structure of Minerals " by W. L. Bragg,l which containslucid and admirably illustrated descriptions of all the principalmineral structures determined up to 1936. A perusal of this book,whilc showing very clearly the enormous advances which have beenmade in our knowledge of oxides, sulphides, silicates, and othergroups, indicates also the large regions of the mineral kingdom stillunexplored.Very little information has accumulated in the pastupon phosphates, for example, and it is satisfactory to observerecent progress in this direction. In other fields, the number ofexact structure determinations of complex co-ordination compoundsremains disappointingly small, in spite of the importance of thistype of substance both practically for determining the structure oforganic molecules and from the point of view of valency theory.From its unit cell dimensions,2 it seems probable that poloniumhas a structure analogous t o those of selenium and tellurium, but oflower symmetry.The nitrides and phosphides of lanthanum,cerium, and praseodymium 3 have rock-salt lattices, and galliumnitride 4 has the wurtzite configuration.1 Oxford University Press, 1937.2 M. A. Rollier, Gaxzetta, 1936, 66, 797.3 A. Landelli and E. Botti, Atti R. Accad. Lincei, 1936, [vi], 24, 459; 1937,4 J. V. Lirmann and H. S. Schdanov, Acta Physicochim. U.R.S.S., 1937,[vi], 25, 129.5, 306160 CRYSTALLOGRAPHY.Oxides.-Valentinite, the high-temperature form of antimQnousoxide, has been found 5 to have a structure, in marked contrast withthe molecular lattice of senarmontite containing infinite covalentdouble chains of the form (I). The Sb-0 distance in the chain is(1.12.00 A. and there is an inter-chain Sb-0 distance of 2-51 A., which isconsidered to represent a weak secondary bond holding thestructure together.The oxygen valency angles are 116" and 132",and those between the antimony bonds are 81", 89", and 93".Another interesting structure is that of selenium dioxide,6 in whichsingle chains (11) occur, with Se-0 distances of 1.73 and 1.78 A. and0 0(11.) -o-8~-o-se-o-8e-o-c,bond angles of 90" and 98" for selenium and 125" for oxygen. Thelinking between the chains is here not as strong as in Sb,O,, theSe . . . 0 distance being 2-63 A. ; on the other hand, the 0 . . . 0distance is the same in both substances, z l i x . , 2 . 5 4 ~ . The Se-0distances in the chain are about 5% less than the sum of thecovalent bond radii, and this is possibly due to resonance betweentwo structures such as (111) and (IV), the former predominating.-0-Se-O-(111.) .c.0The dioxides of selenium and tellurium are among the raresubstances which are transparent in the solid state and havecoloured liquid and vapour phases.Tellurium dioxide is recordedas having the rutile structure, but it is noteworthy that its c-axis isappreciably longer than that of any other rutile-like substance, andin the form of the mineral tellurite it is not tetragonal; are-examination of its structure would be of interest in view of thepossibility of the existence of covalent chains in this substancealso.M. J. Buerger, Amey. Min., 1936, 21, 206; M. J. Buerger and S. B.Hendricks, J. Chem. Physics, 1937, 5, 600; 2.Krist., 1937, 98, 1 ; see alsoM. C. Bloom and M. J. Buerger, ibid., 1937, 96, 365.J. D. McCulIough, J. Amer. Chem. Soc., 1937, 59, 789COX : CRYSTAL CHEMISTRY. 161I n the C 9 structure assigned by It. W. G. Wyckoff 7 toP-cristobalite, the silicon atoms occupy the same positions as thecarbon atoms in diamond, and the oxygen atoms lie midwaybetween them, thus having a valency angle of 180". From newintensity data, W. Nieuwenkamp * concludes that the oxygenatoms revolve in circles about the posit'ions assigned by Wyckoff,so that their valency angle is about 150" and the distance Si-0 is1.59 A. The fact that the transition from high to low cristobalite isnot sharp is in agreement with this suggestion, although the X-rayresults would be equally well explained by a statistical distributionof oxygen atoms over circles of the same radius.New measure-ments have also been made on or-quartz; in this case the oxygenangle is given as 142" and the Si-0 distances as 1-58 and 1.64 A.Pyrolusite, MnO,,1° is reported to have a rutile structure, andtitanium monoxide l1 probably has the sodium chloride lattice withTi-0 = 2.08 A. I n lead titanate, PbTi03,12 where the titanium isalso six-co-ordinated, the Ti-0 distances are given as 2.10, 2.00,and 1.94 A.8uZphides.-A new study of arsenopyrite, PeAsS, by M. J.Buerger 13 shows that it is monoclinic and not orthorhombic asformerly supposed, its structure being a superstructure based uponthat of marcasite. Each iron atom is surrounded by a distortedAs3S, octahedron, one face of which is a triangle of sulphur atomsand the opposite one a triangle of arsenic atoms, so that thearrangement is the same as that in cobaltite, CoAsS, which, however,has much higher (cubic) symmetry, probably because the cobalticis more symmetrical than the ferric ion.The distances areFe-S = 2.19 and 2.28 A,, Fe-As = 2.36 and 2.37 A., and S-As =2.30 A., and Buerger considers that these and other figures indicatethe presence of ferric ion not only in arsenopyrite (a conceptionwhich is not so novel as he suggests) but also in lollingite, FeAs,,and marcasite, FeS,. His conclusions are open to criticism,however; in the case of marcasite, for example, its electricalconductivity is only a small fraction of that of pyrites, whereas thepresence of ferric ions would be expected to increase the conduc-tivity.Nevertheless, a re-examination of marcasite 15 confirmsthat the distances are not the same as in pyrites ; the Pe-S distances7 " Strukturbericht," I, 169.9 F. Machabchki, Foortschr. Min., 1936, 20, 45.10 G. Vaux, Min. Mag., 1937, 24, 521.11 W. Dawihl and K. Schroter, 8. anorg. Chcm., 1937, 233, 178.12 S. S. Cole and H. Espenschied, J. Physical Chern., 1937, 41, 445.13 2. Krist., 1936, 95, 83; Amer. Min., 1937, 22, 48.14 M. L. Huggins, 2. Krist., 1937, 96, 384.15 M. J. Buerger, ibid., 97, 504.REP.-VOL. XXXIv. F* 8. Krist., 1937, 96, 454162 CRYSTALLOGRAPHY.are 2.25 and 2-23 A. (2.26 in pyrites) and the S-S distance is 2.21 A.(2.10 in pyrites).The reason for this increased S-S distance is notclear.The structure of palladous sulphide16 proves to be morecomplicated than that of ~ooperite,~' the platinous analogue, butshows the same essentjial feature, viz., a tetrahedral environmentof sulphur atoms by metal atoms each of which is surrounded byfour sulphur atoms in a plane. As in cooperite, the planar andtetrahedral systems are both distorted to accommodate each other,but to a greater extent; whereas the S-Pt-S angles are 824" and972~"~ the angles between Pd-S bonds vary from 77" to 100".Three types of PdS, co-ordination occur in the structure, slightlypuckered squares, plane rectangles, and plane trapeziums, andfrom the smaller extent of the distortion in the first case it seemsprobable that there is greater resistatnee to deflection of the bondsout of the plane than in it.In any case the resistance of the planeconfiguration to distortion is at least as great as that of thetetrahedral, since some of the Pd-S-Pd angles differ from 109*" byas much as 14". The Pd-S distances range from 2.26 to 2.43 A.,and this variation of nearly 0.2 A. is perhaps further evidence ofthe stability of the planar and the tetrahedral configurations.Apart from its bearing on the above stereochemical points, thestructure of palladous sulphide is of special interest on account ofits isomorphism with braggite (Pt,Pd,Ni)S,18 the first mineral tobe isolated and determined by X-ray methods.Among other sulphides studied,lg the stmcture of cubanite,CuSFe,S3,20 is notable for the occurrence of the iron atoms inpairs.The strong tendency of boronto form chains or nets with oxygen (as in calcium borate and boricoxide glasses) is further exemplified by the structure of potassiumrnetaboratey2l which has the structure IC,(B,O,).In this case theBO, ion has polymerised to form a six-membered flat ring of threeBO, triangles which may be looked upon as a resonance structurebetween (V) and (VI), with the former predominating, since theB-0 dista'nces are 1-38 A. in the ring and 1.33 A. outside it. TheXaZts of Oxygen Acids.-Micates.16 T. F. Gaskell, 2. Krist., 1937, 96, 203.17 F. A. Bannister, Min. Mag., 1932, 23, 188.18 Idem, {bid., p. 626; 2. Krist., 1937, 96, 201.G. A. Harcourt, Amer.Min., 1937, 22, 517; D. Lundqvist and A.Westgren, Arkiv Kemi, Min. Ceol., 1937, 12, B, No. 23; W. Biltz, J. Laar,P. Ehrlich, and K. Meisel, 2. anorg. Chem., 1937, 233, 257; W. S. Miller andA. J. King, 2. Krist., 1936, 94, 439.20 M . J. Buerger, Amer. Min., 1936, 21, 205.2 1 W. H. Zachariasen, J . Chem. Physics, 1937, 5, 919163 COX : CRYSTAL CHEMTSTRY.angle 0-B-0 in the ring is 1134". This resonating system bears amarked resemblance to certain organic structures such its the C3N3- 8 ?oHB\O/B\o -o/B\o~B\o-o/B\o OHB 0 + 0- I 1 + II -(*-(V.) VI.1 (VII.)ring in cyanuric chloride and should have high diamagneticanisotropy.22 Since NaBO, is isomorphous 23 with the potassiumsalt, its structure is presumably the same, and it seems doubtfulwhether the Raman spectrum of its solution, which is said24 toshow the presence of BO,- ions, has been correctly interpreted.N.ElliottZ5 has remeasured the G O and the N-0 distance incalcite and sodium nitrate and obtained the values 1 . 3 1 3 ~ . and1.210 A. respectively. Whereas the former is in good agreementwith the expected value, the predicted26 N-0 distance is 1 . 2 6 ~ .This discrepancy is attributed to a hitherto unrecognised effect,that of the resultant charge carried by an ittom on its covalentradim. It is pointed out that the progressive diminution in theradii of the neutral atoms carbon, nitrogen, oxygen, and fluorinemay be regarded as due to the inereatsing effective nuclear charge,and that in the nitrate ion (VII) the covalent radius of N+ shouldtherefore be smaller than that of N, and that of 0- larger than thatof the neutral atom.These two effects cancel approximately inthe case of the N+-0- bond, but the N+=O distance is estimatedt o be about 0.05 A. less than NZO (1.18 A.), with the result that thepredicted N-O distance for the actual structure of the nitrate ion[produced by resonance between the three possible forms of (VII)]is now in good accord with experiment.J. Beinterna 2' finds that although some per-rhenates andperiodates have the scheelite (CaWO,) structure, others (e.g.,CsReO,) have a very similar orthorhombic structure which it isproposed to call pseudo-scheelite. The scheme on p. 164 is suggestedto represent the effect of ionic size on the structure of RXO,compounds; tvit>h very small R and X ions, e.g., boron and22 Seep.185.23 S. Fang, J. Amer. Ceramic SOC., 1937, 20, 214; cf. S. 8. Cole, S. R.Scholes, and C. R. Amberg, ibid., p. 215.24 J. R. Nielsen and N. E. Ward, J . Chem. Physics, 1937, 5, 201.2 5 J . Amer. Chem. SOC., 1037, 59, 1380.26 L. 0. Brockway, J. Y . Beach, and L. Pauling, ibid., 1935, 57, 2693.27 8. Krist., 1937, 97, 300164 CRYSTALLOGRAPHY.aluminium phosphates, the structure approximates to that ofp-cristobalite. i Cssium osmiamatePseudo-scheeliteScheeliteMonazite Barytes ' Zircon Anh ydrit eAluminium phosphateWolframite ' Boron phosphateDiminishingradius of cationIt------+Diminishing radius of XThe significance for mineral chemistry generally of the tetrahedralco-ordination of silicon and aluminium is now fully recognised andthe classification of mineral structures on the basis of differentaggregations of SiO, and A10, tetrahedra has been one of theoutstanding achievements of modern crystallography. It is clear,however, that in principle any cation of small radius and largecharge may be able to co-ordinate oxygen tetrahedrally and thatin the most general classification of mineral types, ions such asP5*, Ass+, Ge4+, Ti4+, and Fe3+ should be regarded as capable ofplaying the same r81e as silicon, while Be, Mg, and Zn may takethe place of aluminium.An outstanding example of the co-ordinating power of a small highly charged cation is afforded bysilicon pyrophosphate,28 Si[P,07], in which (as in other cubicpyrophosphates) the phosphorus occupies a tetrahedral position,forcing the silicon into octahedral co-ordination, so that thestructure contains [P207] groups similar to the [Si,O,] groups inhemimorphite, thortveitite, Sc,Si,07, and gehlenite. It is interestingto note also that the close analogy between gehlenite, Ca,A1,Si07,and hardystonite, Ca,ZnSi,O,, is not due primarily to a commonsilicon-oxygen structure but to the possibility of zinc replacingaluminium in tetrahedral co-ordination.To take account of such cases as these, H.Strunz 29 has developeda system which constitutes a simplification of the more completeclassification of P. Niggli.30 The general formula of a mineral iswritten[RK* :Owl ( O,OH,F),]R~~VIA,,xH,Owhere RKom and RKpV1 are cations with co-ordination numbers 4and 6 respectively, and A is a cation with co-ordination number38 G.R. Levi and G. Peyronel, 2. Krist., 1936, 92, 190 ; G. Peyronol, ibid.,94, 311.29 Ibid., 1937, 98, 60; cf. H. Berman, Amer. Miiz., 1937, 23, 342.30 See Anm. Reports, 1933, 30, 387COX : CRYSTAL CHEMISTRY. 165greater than 6 (usually alkali or alkaline-earth ions). The squarebrackets enclose the whole of the complex electronegative part ofthe structure, the 0 before the vertical bar representing oxygenengaged in tetrahedral co-ordination and the (O,OH,F) followingit representing the anions not so engaged (" eingelagert " or" embedded " anions). Cations with co-ordination number 3 mustbe put inside the square bracketas.Six classes of minerals are thendistinguished :I. Framework structures. Examples : orthoclase, [Si,AlO,]K,and phenacite, [Be,SiO,]. Note that the latter does not contain acontinuous silicon-oxygen framework and would not be put in thiscategory in a classification based on SiO, and AIO, tetrahedraalone.[Si,AIO1,l (OH),]Al,K, and hemimorphite, [Zn,Si,O, (OH),]Ii,O.11. Layer structures. Examples : muscovite,111. Chain structures. Example : amphibole,IV. Group structures (RX, tetrahedra linked together to formfinite groups). Examples : barysilite, [Si,O,]Pb,, and wollastonite,[Si,O,]Ca, .V. Island structures (containing isolated RX, tetrahedra).Examples : olivine, [SiO,](Mg,Fe), ; titanite, [SiO,(O]TiCa ; andmany phosphates, arsenates, sulphates, etc.[Si,O,,l( OH)4]Al,(Mg,Fe),Cal,, which contains both [SiO,] and[Si,O,] groups.rsi*o,, I (OH),13%5Ca,.VI. Mixed structures.Example : vesuvianite,This primary classification is subdivided according as embeddedanions are present or not, etc.No great novelty appears to be associated with this scheme forthe systematisation of mineral structures when stated briefly asabove, and indeed, it does not bring about any change of outlookon the majority of silicate structures already investigated. At thepresent time, however, minerals of continually increasing complexityare the object of detailed study, and a classification such as that ofStrunz, in which the importance of cations other than silicon andaluminium in tetrahedral co-ordination is emphasised, should bevery helpful.Numerous phosphates and arsenates in particularhave been studied recently, and their relationships to correspondingsilicates demonstrated. The aluminium phosphate structure 31 isderived from that of cristobalite by replacement of silicon byaluminium and phosphorus, and in addition to the pyrophosphates31 F. Machetschki, Fortachr. Min., 1936, 20, 47166 CRYSTALLOGRAPHY.mentioned above, that of magnesium32 has been shown t o haveessentially the same structure as thortveitite, Sc,Si,O,. Aninteresting stereochemical point is that in these substances and inhemimorphite the Si-0-Si and P-0-P angles are 180", whereas inthe Si,O, groups in melilite the Si-0-Si angle is about 130°, whichis of the same order as the oxygen valency angle in per- andpyro-sulphates.The pyrophosphates furnished thefirst examples of shared PO4 tetrahedra ; another interesting caseis that of aluminium metaphosphate, Al(PO,),, the main structuralfeatures of which have been determined by L.Pauling and J.The lattice containsP4OI2 groups (Fig. 3) consisting of aring of four PO4 tetrahedra eachsharing two corners; the other twocorners of each PO4 tetrahedron areshared with AlO, octahedra.The relationships between silicates,phosphates, and arsenates is wellshown34 by the series andalusite,A1(A10)Si04 ; libethenite,Cu( CuOH)P04 ;olivenite, Cu(CuOH)As04 ; andadamine, Zn(ZnOH)As04. The struc-ture of the last mineral has now beenworked out in detail 35 and proves to be very similar indeed to thatof andalusite, containing the unusual five-co-ordinated trigonalbipyramid [Zn040H] corresponding with the AlO, group inandalusite.The shortest As-0 distance is 1 * 5 9 ~ . , and the maindifference from andalusite is the presence of hydroxyl bonds oflength 2-68 A. A point of some interest is that sdamine is probablyclosely related to higginsite Ca( CuOH)As04, descloisite(Pb,Zn)(PbOH)VO,, and particularly tilasite Ca[Mg(OH,F)]AsO,,which in turn appears 36 to have the structure of sphene Ca(TiO)SiO,.Since in this last mineral titanium has the usual octahedralco-ordination, a detailed study of the whole series would be usefulin elucidating the conditions which determine the change from5- to 6 - co-ordination .Although hydroxyl bonds undoubtedly pIay an important partas far as the energetics of crystals are concerned, their influencein the geometry of acid radical structures is frequently quite34 H.Strum, ibid., 1936, 94, 60.36 H. Strum, ibid., p. 7.Phosphates, arsenates, etc.FIG. 3.32 V. Caglioti, Atti V Congr. Naz. Chim., 1936, 1, 310.33 2. Krist., 1937, 96, 481.35 P. Kokkoros, ibid., 1937, 96, 417COX : CRYSTAL CEEMISTRY. 167small, since the length of the hydroxyl bond is very little differ-ent from the ordinary ionic 0-0 distance. Thus pharmacolite,C~[ASO,OH]~H,O,~~ and brushite, CU[PO,OH]~H,O,~~ have unitcells and presumably atomic arrangements very close to that ofgypsum, and similarly hamlinite, [P,O,OH] (A102H2)Sr, is nearlyrelated to alunite, [S,08](A10,H2)Sr.37* 39Studies of substituted apatites *O have shown that nearly all thephosphorus can be replaced by silicon and sulphur without anyessential change in structure, and have also led to the suggestionthat the carbon present in some apatites partly replaces phosphorusin tetrahedral co-ordination and partly occupies calcium positions ;in the latter case slight adjustment of the oxygen positions issupposed to take place so that CO, groups are formed.The generalformula for apatites should thus be written :Complex Ions and Co-ordination Compounds.-Of complex saltscontaining AX, groups (X = F, C1, CN, OH, H,O, NH,, NO,, etc.)over a hundred are known to possess cubic structures with abetween 10 and 11 A., in which the complex ions lie on a face-centred (Le., close-packed) lattice.Apart from the case of nickelphthalocyanine,4l one of these, [Zn(H,0)6]( Br0,),,42 is the onlycomplex compound to be analysed completely by Fourier methodsduring the period under review. The Zn(H,O)6 octahedron is verynearly regular, with Zn-H,O = 2.12 A., and the pyramidal bromateion is considerably smaller than previous measurements suggested,the distances being Br-0 = 1.54 A. and 0-0 = 2.43 A. In additionto the link to the zinc atom, each water molecule has two hydroxylbonds of 2.72 and 2.74 A. to oxygen atoms, the angle between thembeing 121". The general environment of the water molecules isthus very similar to that in various other salt hydrates (e.g.,CuS04,5H20).M.van Driel and H. J. Ver~eel,*~ assuming the dimensions ofthe nitrite group from sodium nitrite, have shown that in triplenitrites of the type A,[M(NO,),] and A,B[M(NO,),] the X-ray datarequire the NO, groups to be attached to the metal atom bynitrogen and not by the oxygen atoms as had been suggested37 B. Gossner, Portschr. Min., 1937, 21, 34; 2. Rrist., 1937, 96, 488.38 P. Terpstra, ibid., 9'7, 229.39 S. B. Hendricks, Arner. Min., 1937, 22, 773.40 D. McConnell, ibid., p. 977; J. W. Gruner and D. McConnell, 2. Krist.,41 See p. 187.43 S. H. Yu and C. A. Beevers, 2. Krist., 1936, 95, 426.43 Ibid., p. 308.1937, 97, 208168 CRYSTALLOGRAPHY.earlier. The Co-N distance in the cobaltinitrites is given as2 .0 3 ~ . Other compounds which prove to have the same generaltype of structure are several ferr~cyanides,~~ chloro- a-nd bromo-antim~niates,~~ ferrihexaflu~rides,~~ hypophosphite hexahydrates,[M(H,O),] (H2P0,)2,47 and magnesium chlorite hexahydrate,[Mg(H20)6](C102),.48 The lower symmetry of the anions in the lasttwo cases reduces the crystal symmetry from cubic to tetragonal,but without any essential change in structure type. All theantimony atoms in the lattice of A2[SbX6] (A = alkali metal,X = halogen) appear to be equivalent, so that the possibility ofalternate ter- and quinque-valent antimony in the structure is ruledout. The magnesium atoms in Mg(N0,),,4CO(NH2),,2H20 49 lie onsymmetry centres, so that if, as seems probable, the octahedralcomplex [Mg4(urea)2H20] is present, the water molecules in itoccupy trans-positions.Various quadricovalent derivatives of bivalent lead and tin,50cobalt and manganese 51 have been shown from considerations ofcell dimensions and symmetry to have planar configurations.Thestructure of the alkali pentabromodiplumbates, A P ~ , B I = , , ~ ~ is builtup of alkali and bromine ions together with PbBr, molecules, inwhich Pb-Br = 2.89 A. and the lead valencyEt \ /Br, /Et angle is 854'. I n dimeric diethylmonobromo-Et/ kBr/ gold (VIII), the planar distribution of auriccovalencies is confirmed; 53 the Br-Au-Brangle is approximately loo", and the Au-Brdistance 2.65 A. The relations between various double cyanideshave been further studied,54 but the suggested 55 planar configur-ation of [CdBr,] in Ba[CdRr4]4H,0 is rendered still more unlikelyby the results of an optical examination 56 of'the substance.Au Au(VIII.)44 R.Rigamonti, Guzzettu, 1937, 67, 137, 146; S. Fordham and J. J.45 K. A. Jensen, 2. anorg. Chem., 1937, 232, 193.4 0 W. Minder, 2. Krist., 1937, 98, 15.4 7 A. Ferrari and C. Colla, Gaxzetta, 1937, 67, 294. 48 Idem, ibid., p. 424.49 J. Y. Yee, R. 0. E. Davis, and S. E. Hendricks, J . Amer. Chem. Soc.,50 E. G. Cox, A. J. Shorter, and W. Wardlaw, Nature, 1937, 139, 71.5 1 E. G. Cox, A. J. Shorter, W. Wardlaw, and MT. J. R. Way, J., 1937,52 H. M. Powell and H. S. Tasker, ibid., p. 119.53 A. Burawoy, C. S. Gibson, G. C. Hampson, and H. M. Powell, ibid.,54 M. Brasseur and A.de Rassenfosse, Mkm. Acad. roy. Belg., 1937, 16, 1 ;55 Idem, ibid., p. 22.513 F. M. Quodling and D. P. Mellor, 2. Krist., 1937, 97, 522.Tyson, J . , 1937, 483.1937, 59, 570.1556.p. 1690.Bull. SOC. TOY. Sci. Libge, 1937, No. 1, 20RANDALL : THE STRUCTURE OF LIQUIDS AND AMORPHOUS SOLIDS. 169Other investigations 57 of complex compounds include severalof the heteropoly-acids 58 and a further study of phosphine andarsine derivatives of argentous and cuprous halides, 59 the mainfeatures of which were described last year .60E. G. C.3. TXE STRUCTURE OF LIQUIDS AND AMORPHOUS SOLIDS.During the last few years there has been a remarkable interestin liquids and amorphous solids, and it is significant of the changeof outlook that the tern1 " structure '' is now used without question.Not so very long ago it was usual to compare the liquid with thegas rather than the solid, but elementary considerations of density,the entirely different dependence of viscosity on temperature inthe two cases, and the evidence of X-ray diffraction experiments,have contributed to the fundamental change of outlook.It is the object of t'his section to consider the evidence of X-raydiffraction, and t o indicate how this method has helped in thegeneral development of facts and ideas concerning liquids andamorphous solids.A detailed account of this aspect of the subjecthas been given comparatively recently in book form; moregeneral discussion of the liquid state is to be found in a recentvolume of Faraday Society Discussions,2 and in another section ofthese report^.^The comparatively fixed positions of atoms or molecules incrystalline solids give rise to the familiar sharp diffraction spectra.In a gas, however, in which the atoms or molecules are far apartcompared with the wave-length of X-rays, the intensity of thescattered coherent beam a t any given angle depends only on thescattering unit and the number of atoms; the question of the' arrangement ' of the atoms with respect to one another does notarise.The intensity of scattering by a monatomic gas such asargon is given by the expression kP . N .fe2, where P is equal to(1 + ~0~228)/2, 28 being the scattering angle, and f e is the ratio ofthe amplitude of the wave scattered by a single atom to thatscattered by a single electron; fe is in fact the well-known structure5 7 H.A. Klasens and P. Terpstra, Rec. traw. chim., 1937, 56, 673; J. A. A.Kctelaar, Physica, 1937, 4, 619; A. F. Wells, 2. Krist., 1937, 96, 433.5 8 0. Kraus, Nutumuiss., 1937, 25, 250; 2. K r i s t . , 1936, 94, 256; J. H.Sturdivant, J . Amer. Chem. SOC., 1937, 59, 630; J. S. Anderson, Nature,1937, 140, 850.513 F. G. Mann, A. F. Wells, and D. Purdie, J., 1937, 1828.Go Arm. Reports, 1936, 33, 167; A. F. Wells, 2. Krist., 1936, 94, 447.1 J. T. Randall, " The Diffraction of X-Rays and Electrons by AmorphousSolids, Liquids, and Gases," London, Chapman and Hall, 1934.2 Trans. Paraday SOL, 1937, 33, 1. 3 seep. 75170 CRYSTALLOGRAPHY.amplitude of X-ray crystallography, which arises because of thefinite size of the atom and consequent interference effects withinit; k involves fundamental physical constants and those of theapparatus. In a liquid, even a monatomic liquid such as an alkalimetal, the density is such that the atoms are only, on the average,a little farther apart than in the solid.X-Rays scattered by oneatom will interfere with those scattered by its nearest neighbours.The neighbours are constant neither in number nor distance, andany effects observed when X-rays are scattered by liquids are aresult of the average distribution of atoms around any other. Theliquid is to be regarded as homogeneous in that the averagedistribution is independent of any atom we may choose. It is theobject of X-ray analysis to try to give more precise informationconcerning this distribution.The form of the expression for the scattering of X-rays by aliquid can most easily be seen by consideration of the scattering bya more and more complicated single molecule.The expressions inthe simpler cases are precisely those for gaseous molecules. If thesingle molecule is increased enormously in size, the scattering is thatof any piece of matter in which distances from atom to atom areknown. P. Debye was the first to develop the expression in thisway.4 He showed that if there were two kinds of atom p and q,the scattering intensity for X-rays of wave-length A would be givenI - PCZfpfq sinsrpq/wpq . . . . (1)byP 4where fp and fs are the structure amplitudes for the two types ofatom, rpq is the distance between atoms p and q, s = 41~0/1, and Phas the same meaning as before.Those familiar with this type ofexpression will realise that it reduces in simple cases to the fornmlzfor single molecules. For molecules containing one kind of atomI - Pnf2X sinsrn/srn . . . . . ( 2 ) O d YnWhere the interatomic distances are unknown, it is necessary tointroduce the idea of the average distribution of scattering matteraround any given atom ; 4xr2g(r)dr represents the number of atomslying between spheres of radii r, r + dr, surrounding any atom, andg ( r ) is called the distribution function. If we consider the case ofa monatoniic liquid, expression (2) can be transformed intoI - Pnf2Z sin synlsrn .g(r)dr . . . . (3)nAnn. Physik, 1915, 46, 809RANDALL : THE STRUCTURE OF LIQUIDS AND AMOSPHOUS SOLIDS. 171The more familiar form of this equation isI = kPnf2(l + 4m2[g(r) - p] . sin srjsr . dr ] . (4) idawhere p now represents the average density of the liquid in atomsper C.C. F. Zernike and J. A. Prins were the first to develop thisform of the expression, apparently without realising that it wasimplicit in Debye’s much earlier equation (2). As Debye did notapply this equation to the structure of single molecules for someyears,6 it seems probable that he did not realise its great importance.By the use of Fourier’s integral theorem,’ it is possible to putexpression (4) into a much more useful form, in which the distributionfunction is removed from under the integral sign, and replaced byan expression depending on the observed intensity of scattering.By puttingit can be shown that( V P -f2)/f2 == +(s)4nr2g(r) = 4nr2p + 2r/7t.lorn s$(s) . sin rs . ds . (5)The development of (4) and ( 5 ) has been set out in some detai1,sas it is on these that all quantitative estimates of the atomic ormolecular distributions within liquids and amorphous solids havebeen made.The practical importance of ( 5 ) over (4) is obvious, for it allowsus to deduce g(r) from observed intensities. To apply (4) to apractical case requires the insertion of inspired guesses at probableforms of g(r), and the working out of a laborious integral before i tis known whether g(r) is of the correct form.These equations asthey stand may be applied only to monatomic liquids, or to liquidsin which there are two equivalent scattering units, as in potassiumchloride; or where one unit scatters negligibly compared with theother, e.g., the hydrogen of water or hydrogen peroxide. There isno reason, however, why the equation cannot be used for molecularliquids in a limited way. For example, the application of theequation to sulphuric acid implies that the g(r) now refers to thedistribution of molecules, and the f 2 of equation (4) musk now bereplaced by the scattering function for the single molecule-in thiscase effectivelyfS2 + 4fO2 + 12jO2 sin sr/sr + 8fsf0 sin sl/sZ2. Physik, 1927, 41, 184.6 P. Debyo, L. Bewilogua, and F. Ehrhardt, Ber. Verhandl.Sachs. Akad.7 H . Bateman, “ Partial Differential Equations of Mathematical Physics,”* See ref. (10); also J. T. Randall, Proc. Rag. SOC., 1937, A , 159, 83.Wiss., 1929, 81, 29.p. 206, Cambridge University Press, 1932.Idem, Nature, 1936, 138, 842172 CRYSTALLOGRAPHY.where thef’s have obvious meaning, and r is the distance betweenoxygens, and I the distance from oxygen to sulphur. I n otherwords, it is necessary that the structure of the single moleculeshould be known before the general case of a complex liquid canbe solved from X-ray measurements. Knowledge of this kindfrequently exists from investigations of the solid or the vapour.Accurate results can only be obtained from (5) if greah care is takento obtain reliable values of the scattering a t large angles, and forthis either a hydrogen camera or a vacuum camera together withstrictly monochromatic radiation is advisable.Equations (4) and( 5 ) may also be applied to amorphous solids, such as glasses; thereis of course no restriction with regard to crystalline solids. B. E.Warren and N. S. Gingrich lo have, in fact, applied these equationsto the analysis of complicated powder photographs ; although theprocess is extremely laborious, it is obviously a possible methodwhere single crystals cannot be obtained. With regard toamorphous solids, it is clear that g(r) will give a space average ofthe distribution of atoms around a given one, whereas, in the caseof liquids, the g( r ) derived from the experimental intensity curvesis a time as well as a space average.Much of the earlier inspiration concerning both liquids andamorphous solids was derived from the work of G.W. Stewart,llwho was the first to show the general similarity between the X-raypatterns for liquids and the corresponding solids. Although suchsimilarity by no means always exists, the idea gradually grew upthat there was a tendency for the liquid to imitate the solid ingeneral atomic or molecular arrangement. I n a long series ofpapers, Stewart had developed the idea of cybotaxis, or theexistence of groups of molecules in the liquid. Stewart confinedhis attention to organic molecules, where the anisotropy predisposesthe molecules to some sort of arrangement over small elements ofvolume. This anisotropy on an exaggerated scale is responsible forthe unusual stages apparent between true solid and liquid which isobserved with liquid crystals.l2. l3 It is easy to see such tendencyto arrangement of molecules by the use of two-dimensional modelsof, e.g., grass seeds or small rods.Such two-dimensional modelsare in fact highly instructive, and not nearly so trivial as mightappear. They were first introduced by J. A. Prins,l4 who madethe important observation that the g(r) function was of a very10 PhysicaZ Rev., 1934, [ii], 46, 368.l1 Rev. Mod. Physics, 1930, 2, 116; Physical Rev., 1931, [ii], 37, 9.l2 See op. cit., ref. (l), pp. 251-261.13 J. T. Randall, Trans. Faraday SOC., 1933, 29; Discussion on Liquidl4 Naturwiss., 1931, 19, 435.CrystalsRANDALL : THE STRUCTURE OF LIQUIDS AND AMORPHOUS SOLIDS.173similar type for two-dimensional models and for actual liquids.W. E. Morrell and J. H. Hildebrand l5 have extended this work tothe study of three-dimensional models. By the use of gelatin ballssuspended in a gelatin sol of the same density, they have shown,from thousands of photographs taken simultaneously in pairs a tright angles, that the distribution function for such balls is verymuch the same as t'hat proposed by Prins for liquid mercury.16The use of two-dimensional models has also enabled J. D. Bernal 17to work out a very suggestive theory, which will be referred to below.Meanwhile reference must be made to a number of otherimportant investigations. The work of J.D. Bernal and R. H.Fowler l8 on the structure of water, and its applications to certainfeatures of ions in solution, is now well known; it is only necessaryto add that equation (4) was used to obtain the approximatetetrahedral distribution of water molecules around a given one.The liquid alkali metals were shown l9 to give a remarkably sharpmaximum in the intensity curve, and this was interpreted as asimilarity between the co-ordination grouping of liquid and solid.Further examination of liquid sodium 2* in greater detail confirmsthis view. Liquid lead and bismuth appear to give identicaldiffraction patterns, and the quantum theory of metals suggeststhat this should be so.21 K. Lark-Horovitz and E. P. Miller 22 havestudied liquid potassium and lithium chlorides by the method ofFourier analysis.They conclude that the number of nearestneighbours in the former liquid is less than in the solid, but it mayreasonably be questioned whether the method yet allows of suchclose distinctions. It is very important from many points of viewthat the method of Fourier analysis outlined in this summary shouldbe used in the investigation of some simple close-packed liquid atdifferent temperatures. Practically no liquid other than water 23has yet been studied in this way.In the field of amorphous solids, the carbonaceous materials suchas soot and cokes, coal, and graphitic acid complexes have receivedsome attention.24 In particular, amorphous carbon has beenexamined by B. E. Warren by the method of Fourier analysis.251 5 J .Chem. Physics, 1936, 4, 224.1 7 Trans. Paraduy SOC., 1937, 33, 27.1 8 J . Chem. Physics, 1933, 1, 515.l9 J. T. Randall and H. P. Rooksby, Nature, 1932, 130, 473.20 L. P. Tarasov and B. E. Warren, J . Chem. Physics, 1936, 4, 236.21 J. T. Randall and H. P. Rooksby, Trans. Paraduy Soc., 1937, 33, 109.22 Physical Rev., 1936, [GI, 49, 418.2 3 H. H. Meyer, Ann. Physik, 1930, [v], 5, 701.24 Op. cit., ref. (l), pp. 188-197.25 13. E. Warren, J . Chem. Physics, 1934, 2, 551.l6 2. Physik, 1929, 56, 617174 CEY STALLOGRAPHY.The apparent differences between some of the forms of phosphorushave been shown to arise from differences in size of crystallites.26Perhaps the more interesting work, however, has been confined toglasses.All true glasses give broad diffraction bands in theirX-ray patterns, and are entirely similar to liquids in this respect.Superposed lines, such as had been observed by R. W. G. Wyckoffand G. W. Mcrey27 are due to devitrification products. It wasfirst shown by J. T. Randall, H. P. Rooksby, and B. S. Cooper 28that the X-ray patterns of simple vitreous oxides and silicates boreobvious similarities to the patterns of the crystalline forms, andthis work was later extended to other vitreous compounds.29 Theconclusion reached at the time, wix., that the glass was composed ofminute crystallites, possibly of slightly differing lattice constants,would in the light of later work receive rather a different inter-pretation. It is unlikely that the regularity of arrangement arounda8ny given atom extends beyond the first and second co-ordinationspheres. Moreover, a glass is not usually in equilibrium, and itappears probable that the positions and the numbers of neighbourswill vary slightly from point to point.The X-rays can only measurethe average effect, and it appears from later Fourier analysis workthat the average effect is usually the same as that in thecorresponding crystal. B. E. Warren and his collaborators 30 haveexamined a number of glasses in this way, in particular, vitreoussilica and germania, boric oxide, and a series of soda glasses. W. H.Zachariasen3l was the first to postulate the extended networkidea, in which the arrangement is never completely regular, andthe unit cell has infinite dimensions.That considerable groups ofatoms must exist as such is suggested by the high viscosity of theglass, but the irregularity of these groups is borne out by the longmelting range of most glasses.The striking feature about liquids and amorphous solids at thepresent time is not so much any new experimental work as thegeneral tendency towards clarification of ideas and development ofnew ones. This is most clearly shown in Bernal's work,17 togetherwith his recent contribution to a Royal Society discussion.32 He26 See op. cit., ref. ( l ) , p. 198.27 J . SOC. Glass Tech., 1925, 9, 256.2* Nature, 1930, 125, 458; J . SOC. Glass Tech., 1930, 14, 219; 2. Krist.,1930, 75, 196.20 J. T. Randall and H. P. Rooksby, Glass, 1931, 8, 234; J .SOC. GlassTech., 1933, 17, 287.30 2. Krist., 1933, 86, 349; B. E. Warren and A. D. Loring, J . Arner.Ceramic SOC., 1935, 18, 269; B. E. Warren, H. Krutter, and 0. Morningstar,ibid., 1936, 19, 202.31 J . Arner. Chem. SOC., 1932, 54, 3841 ; Physical Rev., 1932, 39, 185.32 Proc. Roy. SOC., 1937, A, 163, 320RANDALL : THE STRUCTURE OF LIQUIDS AND AMORPHOUS SOLIDS. 175has shown that a much deeper physical meaning may be attachedto a closer study of distribution functions. This function, eitherfor a two-dimensional model or for a liquid, takes the form of anumber of peaks when plotted againstl r, and the first peak occursa t some small value of r representing the nearest avera.ge approachof surrounding atoms or molecules.The first peak is of outstandingintensity, the subsequent ones gradually diminishing until theyultimately coincide with the mean density line. Each peak ineffect corresponds to a co-ordination sphere, and Bernal hasamplified and extended Prins's notion s3 of artificially splitting upg(r) into a number of functions so thatg(r> = g1+ g2 + g3 + gk + - *each gk corresponding to the kth co-ordination sphere for thecorresponding solid. The approximation to a liquid was finallyobtained by blurring out these sharp peaks by means of an errorfunction. Bernal goes more deeply into the matter by showingthat we may represent the distribution function as one dependingon three variables, the mean distance of closest approach, rl, ofneighbours to a given atom, the number N of close neighbours ofany given molecule, and the irregularity h of their distribution.Thus the greater the irregularity h, the further does the value of Ndepart from the ideal, which is the co-ordination number for thesolid, The development of these ideas leads to the expression forgl(r) of the forme-(T- ~ I W I A ' gdr) = 4 3 - F- *, *where r is the actual distance of the points from the central one.This case may be extended to the more general one of the sum ofthe individual distribution funct!ions, purely from geometricalconsiderations.More precise physical meaning is then obtained bya consideration of the free energy based on the relationF = U - XT + 3kcTlog (hv/IcT)and the €act that U is of the form am/rm + unlrn.The furtherassumption that the entropy is bound, from fundamental con-siderations, to depend on the irregularity h leads to extremelyinteresting conclusions concerning the specific heat of a liquid. Itis apparent from the analysis that Cp consists of three parts andmay be writtenwhere C N and C;, correspond to any changes in energy broughtabout by changes in co-ordination and irregularity, and Cc is the33 J. A. Prins and H. Petersen, Physica, 1936, 3, 147.cp = C N + CA + c176 CRYSTALLOGRAPHY.specific heat of the crystal. For the first time we have the idea ofa configurational specific heat; energy may be absorbed, not forproducing further degrees of freedom, but in changing potentialenergy. In this way it is possible to explain qualitatively thedeviations of the specific heats of liquids from the Dulong andPetit value.The sharpness of transition from crystal to liquid receivedinteresting confirmation from a study of the distribution of circlesaround a given one.In liquid metals, where the interatomic forcesvary comparatively slowly with distance, the co-ordination N willbe high and approximately the same as in the solid; in the liquidrare gases, on the other hand, co-ordination will be low andirregularity 1 will be high. Where low values of co-ordinationnumber exist and the forces vary rapidly with distance, there is notlikely to be such a sharp distinction between liquid and solid, andthe question of the precise nature of liquid helium-I1 is of someinterest.W. H. Keesom and K. W. Taconis 3* have shown thatboth liquid helium-I and liquid helium-I1 give rise to diffuse X-raypatterns. The band for helium-I1 is, however, more diffuse thanthat of I , which may mean a lower co-ordination.35 The viscosityof a liquid on Bernal’s ideas is related to the rate of change ofmutual configuration of the molecules .32 The variation of viscositywith pressure a t a given temperature is empirically represented insome cases by Batchinsky’s relation q = C/(v - vo); if q, is putequal to the volume of the solid, w - vo is then the extra volumetaken up by the molecules in the liquid.The idea of a free volume common to all the molecules in theliquid in virtue of their motion, together with the ideas of “ holes ”in liquids of the order of size of molecular dimensions has beenreintroduced with much effect by Eyring and ~ollaborators.3~ Bymeans of arguments based on statistical mechanics, features of theviscosity relations for liquids, the law of rectilinear diametersrelating to the densities of the liquid and vapour phases, and otherproperties have received interesting interpretations which have beensummarised elsewhere in this v01ume.~J.T. R.4. MOLECULAR CRYSTALS.Progress in the study of crystal structures of molecular substancesmarches parallel with, and is to a large extent responsible for,increasing precision of ideas on the various questions arising out ofthe nature of both intra- and inter-molecular forces. As regards34 Physica, 1937, 4, 28.36 See this vol., p. 81.35 See also P.Kapitza, Nature, 1938,141, 74COX : MOLECULAR CRYSTALS. 177the former, valuable work has been done during the past year inobtaining a more satisfactory theoretical basis for dealing withthose molecules in which ‘‘ resonance ” occurs.has established a convention whereby it is possible to calculate byquantum-mechanical methods a quantity known as the “ order ”of a bond, replacing the empirical “double bond character” ofL. 0. Brockway, J. Y. Beach, and L. Pauling.2 The bond energiesand bond lengths can be obtained by interpolation when the orderis known, and the predicted bond lengths in naphthalene and @herhydrocarbons are in good agreement with the experimental work ofJ. M. Robertson and with calculations by J.E. Lennard-Jones3using a different method. L. Pauling and L. 0. Brockway,4 as aresult of an extended study of many hydrocarbons, have revisedthe value of the C-C distance to 1.34 A., so the percentage reductionson the single-bond radius for double and triple bonds now become13% and 22% respectively. These figures differ only very slightlyfrom those previously adopted by N. V. Sidgwi~k.~ Quantum-mechanical treatment has also been applied in a satisfactory mannerto the diamagnetic anisotropy of organic molecules.6With regard to intermolecular forces, preliminary results 7suggest that in the substitution of deuterium for hydrogen lies apowerful method for studying hydrogen bonds in more detail.While the hydroxyl bond (as in ice or resorcinol 9, has been shownto be practically unchanged by this substitution, it is found thatthe lattice of oxalic acid dihydrate expands markedly along thedirection of the hydrogen bonds when the latter become deuteriumbonds.The increase in length may be as much as 0.04 A. Apartfrom the purely theoretical aspects (which a t present appear to besomewhat involved) of this effect, its existence provides a means ofdetecting the occurrence of hydrogen bonds in a structure withoutthe necessity of detailed analysis, and, in favourable cases, ofdetermining their orientation. It may be added that the differencebetween hydrogen and hydroxyl bonds in this matter affordsfurther justification for maintaining a fairly sharp distinctionbetween the two, contrary to the views of various Americanwriters.W. G.PenneyProc. Roy. SOC., 1937, A , 158, 306.J . Amer. Chem. SOC., 1935, 57, 2693.Proc. Roy. SOC., 1937, A , 158, 280; J. E. Lennard-Jones and J.Turkevich, ibid., p. 297.4 J . Amer. Chem. SOC., 1937, 59, 1223.7 J. M. Robertson and A. R. Ubbelohde, Nature, 1937, 139, 504.8 (Miss) H. D. Megaw, ibid., 1934, 134, 900.9 A. R. Ubbelohde and J. M. Robertson, ibid., 1937, 140, 239.“ The Covalent Link in Chemistry,” 1933, p. 82. 6 See p. 185178 CRYSTALLOGRAPHY.Last year the Erst absolutely direct analysis of an organicmolecule was reported,lO that of phthalocyanine by J. M. Robertson.Similarly a very much simpler molecule, pentaerythritol, has duringOhe current year been analysed completely l1 without making useof chemical evidence. There is no doubt; that cases of this sort willmultiply within the next year or so, and although in general theresults of organic chemistry are sufficiently well established as notto need such independent confirmation, these tendencies are ofgreat importance in indicat,ing that the time is near whencrystallographic technique will successfully be applied to thedetailed analysis of substances whose structures have so far notproved amenable to treatment by the older methods.Excellent accounts of the more technical aspects of thedetermination of molecular structures by X-rays are given byJ.M. Robertson l2 and by H. Mark and F. Schossberger.13SirnpZe Molecular Compounds.-Although the bromine moleculeapproximates in size more nearly to that of chlorine than of iodine,yet it proves to be isomorphous with iodine at - 15Oo.l4 Owingto experimental dSculties, the Br-Br distance, 2.27 A., is subjectto a probable error of about & 0.1 A., but is in excellent agreementwith other data.The Br . . . Br distance between molecules is 3.3 A.Monoclinic (p-) sulphur has been examined by J. T. Burwell; 15there are 48 atoms in the unit cell, and if the existence of S,molecules is assumed, two of them at least must be centro-symmetrical. As this is inconsistent with the accepted structurefor the s8 molecule,16 it is supposed that the central symmetry isattained by oscillation of the molecules in the lattice. Asmonoclinic sulphur is stable only over a few degrees below themelting point, this is a plausible hypothesis; nevertheless, it isremarkable that increasing temperature should destroy the two-foldaxis which exists in the molecule of rhombic sulphur and replace itby a time-averaged centre of symmetry.Further light may bethrown on the sulphur problem by the study of the compoundsRI3,3f& (R = CH, P, As, Sb), preliminary data for which arerecorded by C. D. West.17The rhombohedra1 (C,i or C,) symmetry of the p-form of icereported last year l8 is now confirmed; l9 it is found to have cell10 Ann. Reports, 1936, 33, 214.la Physical SOC. Reports, 1937, 4, 332; see also Science Progress, 1937,18 Ergebn. exalct. Naturwiss., 1937, 16, 183.14 B. Vonnegut and B. E. Warren, J . Amer.Chem. SOC., 1936, 58, 2459.l5 2. Krist., 1937, 9 7 , 123.1' 2. Krist., 1937, 96, 459.l1 Seep. 181.32, 346.l6 Ann. Reports, 1935, 32, 225.Ann. Reports, 1936, 33, 217.N. J. Seljakov, Compt. rend. Acacl. Sci. U.R.S.S., 1937, 14, 183COX : MOLECULAR CRYSTALS. 179dimensions practically the same as those of ordinary (a-) ice, intowhich it is converted by pressure or grinding. I n agreement withearlier work,18 solid hydrogen sulphide is reported 20 to undergotwo transitions due to molecular rotation, at - 147" and - 170".The departure from cubic symmetry in the lower forms can onlybe very slight.21 S. C. Sirkar and J. Gupta22 have proposed astructure similar to that of fluorite; this involves a S-H distanceof 2.5 A. and a H-S-H angle of log", which is much larger than thevalue (92") deduced from infra-red spectra.23 Although a similarchange of valency angle occurs in ice, there can scarcely be anyanalogy between the two cases, as the tendency of sulphur to formhydrogen bridges must be exceedingly small.It has long been known that sulphur trioxide exists in at leasttwo crystalline phases, an ice-like form melting at about 17"(considered by A.Smits to be the stable modification and designated7 by him) and an asbestos-like p-form melting a t about 31". Fromstudies of dielectric constants 24 and Raman spectra 25 it is nowsuggested that the y-form contains trimeric molecules, possiblyhaving the form (I), whereas the p-form consists of endless chains(11) forming a structure resembling that of chromic anhydride.Itis to be hoped that in spite of experimental difficulties (one ofwhich is the effect of X-rays in bringing about the metastable --+stable transformation) more definite evidence on the structures ofthe various forms of crystalline sulphur trioxide will be forthcoming ;-0-80, --o--so,--o- .(11.)on the one hand, some analogies might be expected wit8h thestructure of solid oxygen, whose molecules, known to be 0,, havepresumably the same configuration as the monomeric trioxide,while on the other hand, in view of the resemblance 2G between thepolymerisation of the trioxide and that of aldehydes, it is of interestthat the proposed ring structure (I) is essentially the same as thoseof trioxymethylene and trithioformaldehyde .2720 A.Kruis and K. Clausius, Physikal. Z., 1937, 38, 510.2l E. Justi and H. Nitka, ibid., p. 514.22 Indian J . Physics, 1937, 11, 119.23 €3. L. Cramford and P. C. Cross, J . Chem. Physics, 1937, 5, 371.24 A, Smits and N. F. Moerman, Rec. trav. chim., 1937, 56, 169.25 H. Gerding and N. F. Moerman, 2. physikal. Chem., 1937, B, 35, 216.2 6 S00, e.g., G. Odd0 and A. Sconza, Gazzetta, 1927, 57, 83. 27 See p. 183180 CRYSTALLOGRAFHY.It is remarkable that the crystalline structures of the carbontetrahalides are still somewhat uncertain. C. Finbak and 0.Hassel28 now find that a t room temperature the tetraiodide is notcubic, as was formerly supposed, but is probably isomorphous withthe monoclinic low-temperature modification of the tetrabromide,for which revised cell dimensions are given.The reason for thelow symmetry of these simple compounds is not clear. Thiophos-phoryl bromide, PSBr,, is reported29 to have a cubic structuresimilar to that of stannic iodide; exact parameters were notdetermined.Electron-diffraction studies 30 show that the molecular structuresof arsenious and phosphorous oxides are essentially the same as thatdeduced for the former from early X-ray measurements; 31 theoxygen valency angle in arsenious oxide, however, appears to beconsiderably larger (probably about 140") than that previouslyassigned, and a redetermination of the atomic parameters in thecubic variety (and in senarmontite, Sb,O,) would be valuable.These results confirm that the phosphorus valency angle is about100"; in phosphorous oxide the 0-P-0 angle is 98" (cf.102" inblack phosph~rus,~~ 101" in phosphorus trichloride 33 and 104" inphosphoryl The P-0 dist'ance is 1-67 A. which is lessthan the sum of' the bond radii (1.76 A.) ; a similar contraction hasbeen found for the phosphorus halides. Phosphoric oxide, P,O1,,is less symmetrical, but appears to have approximately the structureshown in Fig. 4; this is derived from that of t'he lower oxide bythe attachment of an additional oxygen to each phosphorus, whichis thus surrounded by four oxygen atoms in a distorted tetrahedron.It is noteworthy that discrete molecules no longer exist in thestructure of the high-temperature form of antimonous oxide(valentinite) .34Aliphatic Compounds.-Very few complete structure determin-ations have been made during the past year.The earlier atomicparameters 35 given for glycine were almost certainly incorrect, and28 2. physikal. Chem., 1937, B, 36, 301; see also H. A. Levy and L. 0.Brockway, J . Amer. Chem. Soc., 1937, 59, 1662.29 I. Nitta and K. Suenaga, Sci. Papers Inst. Phys. Chem. Res, Tokyo,1937, 31, 121; A. E. van Arkel and F. J. Lebbink, Rec. trav. chim., 1937,56, 208.30 I,. R. Maxwell, S. B. Hendricks, and (Miss) L. S. Deming, J . Chew$.Physics, 1937, 5, 626.31 R. M. Bozorth, J . Amer. Chem. Xoc., 1923, 45, 1621.32 Ann. Reports, 1935, 32, 226.33 L. 0. Brockway, Rev. Mod. Physi~s, 1936, 8, 231; H. Braune and p.34 Seep. 160.35 J. Hengstenberg and F. V.Lenel, 2. Krist., 1931, 77, 424.Pinnow, 2. physikal. Chem., 1937, B, 35, 239COX : MOLECULAR CRYSTALS. 181revised values, said to be in better accord with X-ray intensities,have now been proposed ; 36 these lead to bond lengths C-C = 1-47,G N = 1-40, and G O = 1-39 A., all of which are less than the sumof the single-bond radii. It is possible to visualise 37 a system ofhydroxyl (or “ amino ”) bond chains throughout the structure ofcrystalline glycine which would increase its stability and reduceinteratomic distances, somewhat as in the case of oxalicalthough not in so marked a manner ; the above bond distances, iffully confirmed, are thus of very great importance in the develop-ment of the study of hydrogen bridge problems.FIG. 4.Another structure in which hydroxyl bonds play an importantp a t is that of pentaerythritol, C(CH,*OH),, the structure of whichhas been completely determined from Harker and ordinary Fouriersyntheses by F.J. Llewellyn, E. G . Cox, and T. H. Goodwin.39This substance was the cent,re of acute controversy40 some yearsago on account of the supposed possibility of a pyramidaldisposition of the valency bonds around the central carbon atom;although this controversy has long since been decided, on generalgrounds, in favour of the usual tetrahedral configuration, it is ofinterest that the carbon valency angles all prove to be exactlytetrahedral within the limits of experimental error (2” or less),The principal bond distances are C-C = 1-50 and G O = 1-46 A.,both h0.03 A,, so the former distance is definitely less than the36 A.Kitaigorodski, Acta Physicochim. U.R.X.X., 1936, 5, 749.37 M. L. Huggins, J . Org. Chem., 1936, 1, 407; Nature, 1937, 139, 550.38 Ann. Reports, 1936, 33, 218.40 See, e.g., ” Strukturbericht,” 1, 643; Ann. Reports, 1929, 26, 74, 304.39 J . , 1937, 883182 CRYSTALLOGRAPHY.accepted value (1.54~.), while the latter is in accordance withexpectation. It is not clear why the C-C distance should be short,since there can scarcely be any question of double-bond characterin such a substance; on the other hand, very few accuratemeasurements on aliphatic compounds are available for comparisonof a direct kind, while a similarly low value (1.52 A.) is reported forpentaerythritol tetra-a~etate.~~ The molecules of pentaerythritolare held together by a system of hydroxyl bonds remarkablysimilar to that in resorcinol,42 the chief difference being that in thelatter case the bonds form fom-sided spirals, whereas in the formerFIG.5.they extend in two dimensions only, forming closed squares, so thatthe crystals have a layered structure (Fig. 5). The length of thebonds is 2.69 A. This close similarity between the hydroxyl bondsin a phenol and a primary alcohol justifies the assumption that thehydroxyl bond is essentially the same whether in alcohols, sugars,or phenols, so it becomes possible in investigating a substance ofany of these types to eliminate from consideration all moleculararrangements except those in which each hydroxyl group is linkedto two others at a distance of 2.7 A. ; this restriction is of particularvalue in alcohols and sugars where no assistance can be derived41 T.H. Goodwin and R. Hardy, Proc. Roy. Xoc., 1938, A , 164, 369.42 Ann. Reports, 1936, 33, 221183 COX : MOLECULAR CRYSTALS.from optical or magnetic data. Naturally there will be a fewexceptional cases where steric considerations make the applicationof this criterion impossible.A preliminary report 43 has been made of an investigationleading to a structure for pentaerythritol in which the moleculesare differently oriented and have bond distances G-C = 1.57 A.and G O = 1.46 A. Further details will be awaited with interest,but the hydroxyl bond length (2.55 A.) which is involved is almostcertainly too short.A third independent analysis by E. W.Hughes44 is substantially in agreement with that of Llewellyn,Cox, and Goodwin.The molecules of trio~ymethylene,4~ (CH,O),, and trithioform-aldehydeP6 ( CH2S)3, are very similar, both containing Sachsetrans-rings consisting of three carbon atoms alternating with threeoxygen (or sulphur) atoms, but whereas the former has trigonalsymmetry, the latter has only a plane of symmetry, buildingorthorhombic crystals. The bond distances are G O = 1.42&0.03 A.and C-S = l.Sl&O*OS A,, and the valency angles are tetrahedralwithin the (rather wide) limits of error. The intermoleculardistances in trithioformaldehyde me all about 3-6 A., and intrioxymethylene the CH, . . . 0 distance is 3.04 A.More detailedanalysis of these interesting substances is highly desirable, sinceexact knowledge of valency angles would be valuable from severalpoints of view.F. Francis, F. J. E. Collins, and S. H. Piper47 have madeavailable more precise X-ray spacings and other data for manyn-fatty acids and their derivatives which are of considerable valuefor identification purposes in view of the frequent occurrence ofsuch substances in Nature. In addition, since the members of thisseries are more numerous and more readily obtained in a purecondition than those of any other type of long-chain compound,they are particularly suitable for studying the relations betweenchain length and physical properties. The glycerides furnishanother example of substances where accurate X-ray and thermaldata48 are not only essential for determinative purposes, but arelikely to lead to interesting views on the structure of branched-chainmolecules ; structural changes shown by the polymorphic trans-formations of di- and tri-glycerides, for example, may well prove toinvolve changes in molecular configuration as well as in the43 I.Nitta and T. Watanab6, Nature, 1937, 140, 365.44 Private communication.45 N. F. Moerman, Rec. trau. chim., 1937, 56, 661.46 N. F. Moerman and E. H. Wiebenga, 2. Krist., 1937,9'7, 323.47 Proc. Roy. SOC., 1937, A , 158, 691.48 T. M a w , M. R. el Shurbagy, and M. L. Meam, J., 1937, 1409184 CRYSTALLOGRAPHY.distribution of intermolecular forces, in contrast with simplerunbranched chains where the molecules retain a constant formthroughout the range of polymorphic transformati~n.~~ Thechanges which occur in the X-ray spectra of long-chain compoundsnear the melting point have been attributed to partial or completerotation of the molecules about their long axes, and further supportfor this view has been obtained from dielectric-constant measure-ments; 5o the results of A.Muller 51 for two symmetrical ketonesare particularly unambiguous, and show that rapid diminution ofthe directional forces between molecules sets in a t about 15" belowthe melting point so that from that temperature upwards themolecular dipoles are able to orient themselves in the electric field,Ketones are particularly suitable for this work, since the carbonylgroup provides the necessary polarity to show up the molecularrotation in the electric field, and a t the same time it is sufficientlysmall not to make the structure appreciably different from that ofa simple hydrocarbon, for which therefore the results are also valid.With regard to the forces between the terminal groups in fattyacids, which are generally held to be responsible for the inclinationof the molecules to the basal plane, it has been suggested 52 thatoxonium bonds are operative, but it is difficult to see whatadvantages this hypothesis possesses over the accepted ideas ofassociation between carboxyl groups.Among miscellaneous compounds studied, W.H. Taylor 53 hasdetermined the space-groilp and approximate molecular orientationin @-carotene.The molecules are centro-symmetrical, but detailedanalysis has so far not been possible.Aromatic Compounds.-The marked diamagnetic anisotropy ofaromatic compounds has been explained qualitatively by variousauthors 54 on the hypothesis that the diamagnetic currents in suchsubstances are not limited, as is normally the case, to individualatoms, but circulate from one atom to another in orbits of the orderof magnitude of, e.g., a benzene ring. This idea, indeed, is implicitin the theory of molecular orbitals as applied by Huckel and others49 F. D. la Tour, J. Phys. Radium, 1937, [vii], 8, 125; 1,. H. Storks and50 C. P. Smyth and W. 0. Baker, ibid., p. 666; see also A. H. White and51 Proc. Roy. SOC., 1937, A , 158, 403.52 V.V. Tschelincev, Cornpt. rend. Acad. Sci., U.R.R.S., 1937, 16,63 2. Krist., 1937, 96, 150.54 (Sir) C. V. Raman and K. S. Krishnan, Proc. Roy. SOC., 1927, A , 113,511; C. V. Raman, Nature, 1929,123, 945; 124, 412; E. Huckel, 2. Physik,1931, 70, 204, and later papers.L. H. Germer, J. Chem. Physics, 1937, 5, 131.S. 0. Morgan, ibid., p. 655.95COX MOLECULAR CRYSTALS. I85to aromatic molecules. L. Pauling 56 has calculated the diamagneticanisotropy of benzene and similar molecules on the assumption thatthe p , (i.e., the ‘‘ aromatic ”) electrons are free to move under theinfluence of a magnetic field from one carbon atom to an adjacentone. In order to obtain reasonable agreement with experiment hefound it necessary to introduce empirical corrections attributed tovariations in electronic density and bond lengths.F. London 56has now developed a more general theory, of the molecular orbitaltype, which represents aromatic molecules as behaving likesupra-conductors in a magnetic field, and which, withoutassumptions regarding “ aromatic ” electrons, shows that inter-atomic electronic circulation will occur in benzenoid substances andnot in saturated molecules. The theory has the merit of givingcalculated magnetic anisotropies in very good agreement withexperiment without the necessity of introducing correcting factors.On the other hand, combining the older theoretical ideas withexperimental data, (Mrs.) K. Lonsdale 57 has shown that, if it beassumed that the diamagnetic anisotropy of aromatic compounds isdue to the p , electrons occupying molecular orbits which arerestricted to the plane of the atomic nuclei, then the radii of theseorbits, calculated by the classical Larmor-Langevin formula, arerather greater than that of a benzene ring (1.39 A.), increasingsomewhat with the size of the molecule.Moreover, when allowanceis made in this way for the anisotropy, the radii of the orbits of thevalency electrons are found to be in excellent agreement with theaccepted value for the radius of the aromatic carbon atom (0.70 A.).Similar considerations apply to cyanuric triazide and metal-freephthalocyanine ; in the latter case, Mrs. Lonsdale’s calculationsshow that molecular orbitals, encompassing the whole of the16-membered inner ring of the molecule, probably exist.Thesediscussions emphasise the importance of the precise work which isbeing done on the crystal structures and magnetic properties ofaromatic compounds, since only from such work can data beobtained of sufficient accuracy to test the finer details of the varioustheories. The desirability of experimental work on conjugatedheterocyclic compounds is suggested by London’s statement of thesufficient conditions for the occurrence of diamagnetic molecularcurrents; these are, the existence of cyclic chains of equivalentpairs of atoms, and an odd number of electrons per link in the ring.It is not clear whether these conditions are also necessary, and5 5 J . Chem. Physics, 1936, 4, 673.5 6 Compt.rend., 1937, 205, 28; J . Chem. Ph,ysics, 1937, 5, 837; J . Phys.57 Proc. Roy. SOC., 1937, A , 159, 149.Radium, 1937, 8, 397186 CRYSTALLOGRAPHY.whether heterocyclic substances of the type of, e.g., thiophen should,according to the theory, show marked diamagnetic anisotropy.A detailed account of the diamagnetic and paramagneticnnisotropy of crystals has recently been given by Mrs. L~nsclale.~*Complete structure determinations of stilbene 59 and nickelphthalocyanine 6o have been recorded ; preliminary mention hasbeen made of the structures of tolan 61 and anthraquinone,G2 butdetails are not yet available. The structure of stilbene has unusualinterest from the point of view of crystallographic theory. Thespace-group is P2&(Cgh) and its symmetry elements consist ofglide-planes perpendicular to two-fold screw-axes, together witheight symmetry centres; this symmetry can be achieved by theappropriate arrangement of four asymmetric units or two centro-symmetrical units.The structures of very many substances areknown to be based upon this space-group, some having fourmolecules to the unit cell and others two. I n the former case it isassumed that the molecules are crystallographically asymmetric,while if the unit cell contains only two molecules (of finite molecularweight) each must contain a centre of symmetry coinciding with oneof the eight in the crystal lattice. One of the numerous examplesof this is diphenyl. Kow, in the case of the unit cell containingfour molecules, the conditions are more elastic, and it is possiblefor all four to be centro-symmetrical and to Be situated on four ofthe eight symmetry centres in the unit cell, but this is very unlikelybecause two such molecuIes are sufficient for the space-grouprequirements, and double the number would normally produce astructure of higher symmetry.Nevertheless, this exceptionalsituation actually arises with stilbene, the molecules of which aretruly centro-symmetrical although four of them are contained inthe unit cell. The larger number of molecules has made theanalysis more difficult than that of dibenzyl, but the full structurehas been determined with considerable accuracy. Within thelimits of error the molecules, which have a trans-configuration, arecompletely flat, in marked contrast with d i b e n ~ y l .~ ~ This flatnessis due to the conjugation of the central double bond with thebenzene rings; its implications and its influence Qn interatomicdistances are discussed el~ewhere.~* The principal bond lengthsare C-C (in the benzene rings) = 1-39 A., C-C (outside the rings) =1 . 4 4 ~ . , and C-C = 1.33 A. The angle C-GC is 130" and the58 Physical SOC. Reports, 1937, 4, 368.59 J. M. Robertson and (Miss) I. Woodward, Proc. Roy. SOC., 1937, A , 162,6" Idem, J . , 1937, 219. 61 J. M. Robertson, J., 1938, 130.62 B. C. Guha, Mature, 1937, 139, 969.63 Ann. Reports, 1935, 32, 230. 64 Seep. 203.568COX : MOLECTJLAR CRYSTALS. 187shortest intermolecular CH . . . CH distance is 3 .5 8 ~ . In tolan,conjugation maintains a flat molecule, but in addition the triplebond causes the whole molecule to be linear ; the progressive changein molecular form as the central single bond in dibenzyl is replacedby a double bond and then by a triple bond is beautifully shownby the electron-density maps 65 in Fig. 6. (It should be borne inFIG. 6.Dibenxyl. Stilbene. Tolan.. .Scale0- J 'Amind that these two-dimensional projections are not necessarily inplanes parallel to those of the benzene rings, and that dibenzyl is athree-dimensional molecule.)The analysis of nickel phthalocyanine shows that the moleculehas a more nearly tetragonal configuration than has the metal-freecompound. This is probably due to the replacement of the internalhydrogen bridges by the four nickel covalencies.The four Ni-Nlinks are each 1.83 A. in length and almost exactly at right angles;this bond length is nearly equal to the sum of the atomic radii ofneutral nickel and doubly-bonded nitrogen, but it is not yet quiteclear as to what are the exact valency relations around the centralmetal atom, and possibly further investigations of co-ordinationcompounds may show how far a metal atom participates in theresonance phenomena of an organic molecule to which it isco-ordinated. A notable feature of the nickel phthalocyaninestructure is that the increase in two C-N links caused by the covalent65 Reproduced by the courtesy of Dr. J. M. Robertson188 OBYSTALLOGRAPHY.binding of the nitrogens to the nickel atom is accompanied by asimilar expansion of the C-N links in the molecules, so that allremain equal as in the metal-free conipound, although about 0.04 A.longer.Commenting on the fact that the signs of nearly all thestructure factors are determined by that of the nickel contribution,the authors emphasise the advantages, previously noted in theseReports,66 of introducing a metal atom a t a known point in anorganic structure, and suggest that a method of direct analysis ispossible by choosing the metal atom of sufficient scattering powerto " swamp " all the reflections. This attractive procedure maynot prove to be withdut difficulties, however ; it is recognised thatin trial and error analysis the advantage of the presence of a heavyatom is discounted by the fact that the structure factors becomerelatively insensitive to the adjustments of lighter atoms, andsimilarly in direct Fourier analysis the spurious subsidiary maximaand minima associated with the heavy atom would tend to falsifydetail in its neighbourhood.It has been recognised €or some years that, in organic molecularstructures, atoms not maintained in juxtaposition by covalentbonds do not normally approach each other nearer than about3.6..More recently it has been realised that many polynucleararomatic molecules such as diphenyl, the parts of which, from thestandpoint of the older stereochemistry, could rotate aboutconnecting single bonds, are actually maintained in a planar formby the conjugation between rings, which confers some double-bondcharacter on the single bonds.It is thus a matter of some interest 67to study molecules in which there must be a conflict between thetendency to coplanarity and the tendency of groups to repel eachother a t distances less than 3.5 A. Such a molecule is that ofo-diphenylbenzene ; 68 detailed analysis has not yet been made,but it has been shown from magnetic data that the planes of thetwo ortho-phenyl groups are probably inclined a t about 50" to theplane of the parent ring, thus allowing a CH . . . CH distance ofabout 3 A. between them. There is evidence also that even in themeta-position phenyl groups repel each other slightly, since in thecrystals of s-triphenylbenzene the three phenyl groups appear tobe rotated approximately 16" out of the plane of the nucleus.Itshould be clearly understood that there is no evidence from these(or any other) compounds to suggest that the single bonds areotherwise than collinear with the centres of the rings which theylink.6 6 Aim. Reports, 1936, 33, 213.6 7 (Mrs.) K. Lonsdsle, 2. Krist., 1937, 97, 91.6 8 C. J. B. Clews and (Mrs.) K. Lonsdale, Proc. Roy. Xoc., 1937, A , 161, 493COX : MOLECULAR CRYSTALS. 189The unit cells and space-groups of several aromatic compoundshave been determined,6g and in some cases the molecularorientation has been found. Superficially the structures ofhydrazobenzene 70 and p-azotoluene 71 do not appear to resemblethat of azobenzene, but the data for the former are not self-consistent, and further study may show that it falls in thedibenzyl-azobenzene series.The atomic parameters given foracenaphthene 72 are almost certainly incorrect, and according tomeasurements made by the Reporter, the lattice dimensionsassigned to t?hianthren 73 are not primitive; the true unit cellcontains only four molecules, so that speculations regardingpolymerisation are unnecessary. Preliminary data have beenrecorded 74 for a series of quinhydrones ; the suggested interpretationof them is not entirely free from objection, but at least it is clearthat the earlier picture of infinite polymerisation chains by meansof hydrogen bonds 75 is too and it is greatly to be hopedthat the full‘ elucidation of the structure of these interestingcompounds will shortly be possible.Chlorophyll-a itself is amorphous, but by the substitution ofethyl for the phytol group a crystallisable compound can beobtained.This does not appear to have a particularly simplestructure, however,77 and its investigation has not been carriedbeyond the space-group determination.Cellulose.-The results of earlier work on the structure of cellulose,as summarised by K. H. Meyer and H. Mark,78 have been acceptedwithout serious question for some years; it is to be expected,however, that in the near future advances both in technique and inour general knowledge of organic structures will require the olderviews to be modified. Proposals for such modification have in factbeen made during the past year, and although finality has by nomeans been reached, the present time seems appropriate for areview of the situation.69 M.Milone, A t t i R. Accad. Sci. Torino, 1937, 72, 425; I. Nitta and T.Watanab6, Sci. Papers Inst. Phys. Chem. Rm. Tokyo, 1937, 31, 225; M.Prasad and J. Shanker, J . Indian Chem. SOC., 1936, 13, 663; is. Banerjeeand A. C. Guha, 2. Krist., 1937, 96, 107.70 J. Shanker and M. Prasad, Current Sci., 1937, 5, 387.7 1 M. R. Kapadia and M. Prasad, ibid., p. 423.‘i2 K. Banerjee and K. L. Sinha, Indian J . Physics, 1937, 11, 21.7 3 M. Prasad, J. Shanker, and B. H. Peermohamed, J . Indian Chern. SOC.,74 J. S. Anderson, Nature, 1937,140, 583. 75 Ann. Reports, 1933,30,420.7 6 J. Palacios and 0. R. Foz, Anal. Pis. Quim., 1936, 34, 779.7 7 J.A. A. Ketelaar and E. A. Hanson, Nature, 1937, 140, 196; cf. E. A.78 “ Der Aufbau der Hochpolymeren Organischen Naturstoffe,” 1930.1937, 14, 177.Hanson, Proc. K. Rkad. Wetensch. Amsterdam, 1937, 40, 281190 CRYSTALLOGRAPHY.All results agree in showing that the unit cell dimension parallelto the fibre-axis (" fibre-period ") is 10.3-10.4 A., correspondingvery well with the calculated length of one anhydrocellobiose unitin the cellulose chain. This axis has been assumed to be thesymmetry axis b of a monoclinic unit cell, the other dimensions (atright angles to the fibre axis) being a = 8.3 and c = 7.9 A., inclinedto each other at an angle (p) of 84". This cell contains twoanhydrocellobiose units, one of which can be regarded as part of achain running along the b-edge of the unit cell while the other isparallel to it but differently oriented in the centre of the cell.0. L.Sponsler 79 had indeed suggested an orthorhombic cell witha' = 10.7 and c' = 12.2 A., containing four C1, units, but it wasFIG. 7.pointed out 80 that (with small numerical adjustments) this mightvery well be merely an alternative and less fundamental descriptionof the monoclinic cell, which would thus remain the true unit, asshown in Fig. 7.Recently E. Sauter,B1 applying his improved experimentalmethods,B2 has obtained cellulose photographs, showing many newreflections, and has concluded that the unit cell of Meyer and Markhas only half the volume of the true cell, the dimensions of whichshould be a = 10.8, b = 10-4, c = 11-8 A., with p = 85", closelyresembling Sponsler's figures.Apart from the minor question ofexact numerical values (Sauter's results give a slightly higher7s Nature, 1930, 125, 633. (Sir) W. H. Bragg, ibid., p. 634.81 2. physikal. Chem., 1937, B, 35, 83.az 2. Krist., 1936, 93, 93; cf. Ann. Reports, 1936, 33, 224COX : MOLECULAR CRYSTALS. 191density than Meyer and Nark's), the main issue is thus whether ornot the two cellobiose units represent,ed by each of the points A(Fig. 7) are oriented identically as those represented by B ; if theyare, the true cell is as given by Meyer and Mark, and if not, theSponsler-Sauter lattice is more nearly correct. Since in thediscussion 83 of this point the same experimental results have beengiven diametrically opposite interpretations, it may be useful todescribe in detail the facts involved, with a view to clarifying thematter.An X-ray photograph of cellulose taken with the beam parallelt o the fibre shows inter ulia three prominent lines due to planesparallel to the fibre axis (Le., (h01) planes), usually called A,, A,,and A,, with spacings of approximately 6-0, 5.4, and 4 .0 ~ .respectively (Fig. 8, u). If as a result of natural growth, stretching,FIG. S.(a -1 ( h.)or otherwise, tlhe cellulose crystallites are oriented parallel to eachother, the reflections are concentrated into certain arcs of theDebye-Schemer circles and it becomes immediately obvious thatthe planes A, and A, are nearly at right angles. Referred to theMeyer-Mark lattice, these planes have indices (101) and (101).The A, reflection also breaks up into arcs, which according to theolder investigations are nearly at 45" to A, and A , (Fig.8, b) so thatA , is taken to be (002); Sauter on the other hand claims that theyare parallel to A, (Fig. 8, c), in which case, as the spacings of A,and A, are in the ratio of 3 to 2, the former cannot be a first-orderreflection. The indices assigned by Sauter are therefore A, (002),A , (200), and A , (003), necessitating the larger cell dimensionsalready given.It is exceedingly difficult to arrive at a clear-cut decision inmatters of this kind, particularly as the estimation of the positionsof intensity maxima in diffuse rings is liable to considerablesubj ect,ive errors.Nevertheless, an examination of the available83 H. Mark and K. H. Meyer, 2. physikal. Chem., 1937, B, 36, 232; €2.Sauter, &id., pp. 405, 427; 37, 161192 CRYSTALLOGRAPHY.photographs suggests very strongly that the reflection A, is due totwo sets of planes, one approximately parallel to A, and the othera t about 45" to it. There are undoubtedly reflections a t 45"(Fig. 8, b), but in all the photographs they appear to overlapconsiderably more at X than a t Y , giving the effect of 8, b + 8, c.Now in actual fact the A, reflections should not be exactly at 45"but should be a few degrees nearer A,, so that any tendency tooverlapping (on account of imperfect orientation) would be showna t Y rather than X, and the only explanation of the observedcontrary result would seem to be that there is another reflection a tX .Sauter's main conclusion that the unit cell has twice thevolume of Meyer and Mark's thus appears to be correct, but thereflection A, is probably due not only to (003) as supposed by him,but also to (202) and/or (202).A further point established by Sauter is that the b-axis is not ascrew-axis, since the (030) and (050) reflections definitely occur(although not very intensely). His suggested rotation of successiveglucose units to account for this is not acceptable in its presentform, however, either on crystallographic or on stereochemicalgrounds; the arrangement he depicts would certainly remove thescrew-axis but would still result in halving of (OlO), whereas presentinformation regarding valency angles suggests that any largerotation of the glucose rings with respect to each other is unlikely.Nevertheless, the presence of the odd orders of (010) must be takeninto account in any detailed study of cellulose, and is interestingfrom a chemical point of view in that it shows that successiveglucose units in the chain are not crystallographically identical andthat the unit of structure therefore consists of two anhydroglucoseunits.Detailed measurements of the new photographs are not yetavailable, but it is by no means clear what real evidence there isfor a monoclinic unit cell for cellulose, as opposed to an orthorhombicone.It is exceedingly difficult to believe, as Sauter suggests, thatit can be inferred from equatorial photographs that the angle p is85".His photographs were made upon oriented B-cellulose, whichis produced from a sheet of unoriented crystallites by drying undertension; thus, in the oriented specimen there will be approximatelyequal numbers of crystallites with their b-axes pointing in oppositedirections (their unit cells appearing as in Fig. 9 when viewed alongthe fibre axis), so that the photograph should show orthorhombicsymmetry. All previously reported reflections can certainly beaccounted for by an orthorhombic cell of approximately the sameaxial lengths as Sauter's monoclinic cell.I n earlier investigations it was assumed that the cellulose chainCOX : MOLECULAR CRYSTALS. 193in a crystallite were all arranged in the same sense, but as K.H.Meyer 84 has pointed out, the supposition that equal numbers ofchains run in opposite directions is equally plausible, and indeedstatistically this must be so in hydrate cellulose prepared artificially.From the fact that this regenerated hydrate cellulose has the same(or nearly the same?) lattice as hydrate cellulose prepared directlyfrom ramie, Meyer infers that in the native fibre also the chains runalternately in opposite directions. Although this may quite wellbe so, it seems to the Reporter that the above-mentionedresemblance can be explained without recourse to any hypothesisof reversed chains. It is now generally recognised that bondsFIG. 9.between hydroxyl groups are responsible for holding carbohydratemolecules together in the crystalline state, and that other forcesinvolved (as e.g., between CH groups) are relatively unimportant.Now the configuration of cellobiose is such that the six hydroxylgroups have very nearly two-fold axial symmetry; reference toFig, 10 will show that rotation through 180" about an axis through0, perpendicular t o the plane of the paper brings 0, into theposition of 0'3, 0, into that of 0'2, and 0, nearly into the position ofO',.Consequently, as far as hydroxyl-bond formation (whichconditions the molecular arrangement) is concerned, it is largely amatter of indifference if the molecule goes into the latticeupside-down, and a resemblance between regenerated hydratecellulose and that derived from ramie would be expected whetherthe latter contained reversed chains or not.It is of some interest to note that, in order to obtain as close anapproximation to the above-mentioned axial symmetry as possible,it is necessary to arrange 0, and O', slightly differently relative to84 Ber., 1937, 70, 266.ItEP.-VOL. XXXIV. 194 CRYSTALLOGRAPHY.their respective glucose rings, thus destroying the two-fold axialsymmetry parallel to the fibre axis. It is tempting to suggest thatin cellulose there is a statistical distribution of reversed chains andthat the consequent adjustment of primary alcohol groups to formhydroxyl bonds destroys the two-fold axial symmetry along thefibre-axis and gives rise to the “forbidden” (030) and (050)reflections. It should be understood that Meyer’s suggestion is foran ordered distribution of reversed chains, each chain in the latticebeing surrounded by four others running in the opposite direction.It is perhaps hardly necessary to say that at a time when there isstill controversy over the cell-dimensions, a specific suggestion ofFIG. 10.this kind, and still more the development of it to obtain exactatomic positions,85 is entirely speculative. Unless it proves possibleto obtain cellulose preparations of a considerably higher degree ofcrystallinity and orientation than those now available, it is verydoubtful whether it will ever be possible to determine the preciseat’omic arrangement by measurements on cellulose itself. Progresswill more probably be made by utilising exact data regarding theconformation of anhydrocellobiose derived from the study ofcrystalline oligosaccharides in conjunction with the best availableevidence from cellulose.Two further points in connection with the idea of reversed chainsmay be mentioned. The suggestion that cellulose chains mightform closed loops is not a new one; it is evident that if they existin the cellulose lattice then reversed chains (distributed at random)85 K. H. Meyer and L. Misch, Helv. Chim. Actcc, 1937, 20, 232COX : MOLECULaR CRYSTALS. 195must occur, but closed loops do not appear to fit in very well withpresent views on micellar and inter-micellar structure. The otherpoint is that the presence of equal numbers of chains running inopposite directions in the fibre would destroy the polar nature ofthe b-axis and would be more likely to give a structure withorthorhombic rather than monoclinic symmetry ; indeed, onaccount of the symmetrical nature of the cellobiose unit, this istrue for fibres built of unidirectional chains.To sum up, it seems probable that the cellulose unit cell isorthorhombic as suggested by Sponsler, with axial lengths as givenapproximately by him and more accurately by Sauter; in viscoseand similar artificial preparations half the chains are reversed anddist.ributed statistically, but whether this is true of celluloseproduced biologically is a matter for further investigation. In anycase, there is very little evidence at present to show exactly howthe atoms are arranged in the unit cell.In the limited space available it is impossible to discuss numerousother recent investigations 86 of cellulose, but special mentionshould be made of several papers 87 discussing its inter-micellarstructure. E. G. C.E. G . Cox.N. P. MOTT.J. T. RANDALL.86 H. Dostal and H. Mark, Trans. Paraday SOC., 1937, 33, 350; W. K.Ferr, J . Appl. Physics, 1937, 8, 228; G. L. Clark and E. A. Parker, Science,1937, 85, 203; G. L. Clark and A. F. Smith, Rev. Sci. Instr., 1937, 8, 199;0. R. Howell and A. Jackson, J., 1937, 979; J. Gundermann, 2. physikd.Chem., 1937, B, 37, 387; R. Hosemann, ibid., 1937, A, 179, 356; H.Staudinger, Naturwiss., 1937, 25, 673; K. Hess and J. Gundermann, Ber.,1937, 70, 1788, 1800; P. Nilakantan, Proc. Indian Acad. Sci., 1937, 5, A ,166 ; W. A. Sisson, Contr. Boyce Thompson Inst., 1937, 8, 389.8 7 0. Kratky and H. Mark, 2. physikal. Chem., 1937, B, 36, 129; P. H.Hermans and A. J. de Leeuw, Naturwiss., 1937, 25, 524; E. Sauter, 2;.physikal. Chem., 1937, B, 35, 117

ISSN:0365-6217    

DOI:10.1039/AR9373400154

出版商:RSC    

年代:1937

数据来源: RSC

摘要:

ORGANIC CHEMISTRY.A. General.1. THE STRUCTURE AND STEREOCHEMISTRY OF SIMPLEORGANIC MOLECULES.THE purpose of this article is to take two quantities, bond lengthand the heat changes in hydrogenation, and discuss the informationobtained from accurately determined values of them as to thestructure and stereochemistry of simple molecules. Both quantitiescan be measured with a known degree of accuracy and a number ofconclusions can be based directly on them without the need forsubsidiary hypotheses. It will be seen that in many points theyconfirm what is already known from the ordinary methods oforganic chemistry and stereochemistry and show that the simplepictures of molecules deduced by those methods are a closeapproximation to the truth, much closer than appeared to be thecase when physical methods were first applied to organic molecules.In other respects, however, they give valuable information whichcould never have been obtained by older methods; some of thisinformation has an important bearing on the correlation ofstructure and chemical reactivity, and some raises points whichindicate that certain current theories of organic chemistry are inneed of revision.Bond Lengths and Angles.The quantitative data on bond lengths available at the presenttime are fairly extensive, and those for the hydrocarbons and theirhalogen derivatives are discussed in the following paragraphs intheir relation to the structural problems of organic chemistry.Hydrocarbons.-The carbon-carbon single bond distance wasfirst measured in the diamond crystal, in which each atom isbonded tetrahedrally (ie., with bond angles of 109" 28') to fourothers at distances of 1.541 & 0-001a.l This same value withinthe experimental error of & 0.02 or 0.03 A.is observed in ethane,propane, isobutane, neopentane , cycZopropane, cydopentane, andcyclohexane (Table I) according to recent electron diffractionmeasurements on the vapours.2 X-Ray measurements on com-W. H. Bragg and W. L. Bragg, Proc. Roy. SOC., 1913, A, 89, 277; W.Ehrenberg, 2. Krist., 1926, 63, 320.L. Pauling and L. 0. Brockway, J. Amer. Chern. SOC., 1937, 59, 1223.A. Miiller, Proc. Roy. SOC., 1928, A , 120, 437BROCKWAY AND TAYLOR : STRUCTURE AND STEREOCHEMISTRY. 197202 ORGANIC CHEMISTRY.since small differences in energies of activation due to smalldifferences in structure are often responsible for very largedifferences in reactivity.At the same time the resonating moleculeis consistent with all of the observed dimensions. The inadequacyof the single Kekul6 structure is further demonstrated bycalculations of resonance energy, which could not exist in a singlestructure.Anthracene= and chrysene25 also show average ring sizes of1.41 A., a value which is consistent with the intermediate positionwhich these molecules also occupy between benzene and graphite.In the substituted benzenes the ring almost certainly retains itssize 1 7 s 1**19 except in derivatives in which the ring has severalconjugated groups attached. Several methylbenzenes have beenmeasured particularly to determine the length of the bond attachingthe methyl group to the ring.The best X-ray investigation hasbeen made on durene 26 with a resulting Car.-Cal. distance of 1.47 A.The latest electron diffraction examinations o f 1 : 3 : 5-trimethyl-and hexamethyl-benzenes show the value 1.54 & 0.02 A. In these,two values of the ratio Cm.-Cal. to C,,-C,, were used (equal to1.47/1-39 and 1.54/1.39). Qualitative differences between the twotheoretical curves when compared with the photographs led to achoice of the second ratio. Quantitative measurements then gavethe result and estimated error quoted above. It is hard to believethat either result is in error by as much as the difference betweenthem, and a discrepancy exists which can be resolved only withfurther investigation.The high value is also observed for methylethylenes (see above),so the occurrence of a double bond in the benzene ring would notbe expected to shorten the bond to the methyl group.It has beensuggested2' that the resonance in the ring may shorten theexternal bond; the same effect would then be expected in theparallel case of the bond attached to a carboxyl group. In oxalicacid dihydrate this bond is shortened by the conjugation of thetwo carboxyl groups ; but in ammonium oxalate monohydrate,28where the conjugation is inhibited by the twisting of the carboxylgroups into different planes, the carbon-carbon bond is longer than1-54 A. in spite of the resonance between the two C-0 bonds in eachcarboxyl group.The question of the bond length by which a non-conjugatinggroup such as methyl is attached is of some importance as a24 .J.M. Robertson, R o c . Roy. SOC., 1933, A, 140, 79.26 J. Iball, ibid., 1934, A, 146, 140.26 J. M. Robertson, ;bid., 1933, A , 142, 659.27 Ann. Reports, 1936, 33, 76.28 S. B. Hendricks and M. E. Jefferson, J . Chem. Physics, 1936, 4, 102BROCKWAY AND TAYLOR : STRUC!LWRE AND STEREOCHE.MISTRY. 203starting point from which to measure the effect of bond lengthwhen the benzene is part of a conjugated system. An interestingcomparison showing the effect of conjugation can be made amongthe three molecules, d i b e n ~ y l , ~ ~ stilbene,17 and tolan,ls whosestructures have been determined by Robertson (see Fig.6, p. 187).The three distances of interest are the bond length fixing the size ofthe benzene nucleus, that connecting the phenyl to the first atomin the side chain, and that connecting the two side-chain atoms(i.e., in the centre of the molecule). For dibenzyl Robertsonreported the three distances 1.41, 1.47, and 1-58 A., respectively.The accuracy of the location of the atomic positions is less in thismolecule than in the other two because of its more complicatedshape; and recently the investigator suggested 30 that the size ofthe benzene ring in dibenzyl should be reduced t o 1.39a., whichwould automatically raise the second distance to 1.49 A. Althoughthis still leaves a large difference between the side-chain bondlengths, the uncertainty of 0.03 A.in the positions of the methylenecarbon atoms would allow the difference to be materially reduced.In stilbene the three distances are 1.39,1.45, and 1.33 A. The thirddistance corresponds to the double bond. In tolan the distances are1.39, 1.40, and 1.19 A., the last representing the triple bond. As atpresent reported, the bonds holding the phenyl groups in the threemolecules have the distances 1.49, 1.45, and 1.40 A., respectively.The decrease in the second and third shows the effect on a singlebond which is involved in conjugation between a benzene ring anda double or triple bond, respectively. The extra effect in thelatter case may be due in part to the interaction of a triple on asingle bond even without conjugation as observed in methyl-acetylene.X-Ray investigations have been reported for diphenyl,31p-dipheny1benzeneF2 and 4 : 4’-diphen~ldiphenyl,~~ where now thebenzene rings are bonded together without intermediate atoms.In all these the ring size is reported to be 1.41 or 1 .4 2 ~ . and theconnecting bond lengths 1 . 4 8 ~ . If the bond from phenyl to asaturated carbon atom is 1.47-1.49~. long, as suggested by thedurene and dibenzyl results, then the distance 1 . 4 8 ~ . betweenphenyl groups seems much too large, as the following comparisonshows. Accepting the distance 1 . 5 4 ~ . for the bond between twosaturated carbon atoms (Le., each bonded to four atoms) and thedistance 1-48 A. for that between a phenyl group and one saturated29 J.M. Robertson, PTOC. Roy. Soc., 1935, A, 150, 348.30 Private communication.31 J. Dhar, Indian J. Physics, 1932, 7, 43.32 L. W. Pickett, Proc. Roy. SOC., 1933, A, 142, 333.33 Idem, J. Amer. Chm. SOC., 1936, 58, 2299204 ORGANIC CHEMISTRY.atom, we should expect the bond between two phenyl groups to benearer 1 . 4 2 ~ . than 1 . 4 8 ~ . I n addition the conjugation betweenthe rings should have a further shortening effect. On the otherhand, if the bond from the phenyl group to the saturated atom isalso near to 1.54 A., as suggested by the electron diffractionmeasurements on the methylbenzenes, then the shortening to1 . 4 8 ~ . in the diphenyl type molecules is easily understood as theconjugation effect between the benzene nuclei.The existence ofconjugation in these molecules is indicated by their planarstructures, a condition due to a degree of double bond character inthe connecting links, which is to be contrasted with the non-planararrangement of the dibenzyl molecule.Thus the carbon-carbon distances in nearly all of the hydro-carbons which have been investigated support a scheme of bondlengths in which the bonds between saturated atoms are 1.54 A.,double bonds are 1.34 A., and triple bonds are 1.20 A. long. Thesingle bond is affected little, if a t all, when it is adjacent to a doublebond or a benzene ring, but is shortened about 0 . 0 8 ~ . by anadjacent triple bond. I n molecules whose structures as ordinarilywritten contain alternate multiple bonds (conjugated systems), all ofthe bonds between carbon atoms linked to fewer than four atomsare resonance hybrids with distances intermediate betweenthe appropriate pair of the above standard lengths.(Refer-ences 2* lo* 12* 34 have been given to papers discussing the predictionof the lengths of hybrid bonds.) The two important exceptions tothis scheme, durene and dibenzyl, may be noted with the hope thatfurther investigations on molecules of this type may be undertaken.The lengths of carbon-hydrogen bonds have been measured inthe three typical cases with single, double, and triple bonds onthe carbon atom to which the hydrogen atom is bonded. Veryaccurate results have been obtained for the first and the third fromspectroscopic data. I n methane 35* l 3 the C-H distance is 1.093 A.and it is probable that practically this same value would beobserved whenever the carbon atom involved forms four singlebonds. When the C-H bond is adjacent to a triple bond, itslength is 1.057 A., this value being reported for acetylene andhydrogen cyanide.36 I n ethylene the spectroscopic analysis hasbeen performed only for the molecule containing the lighter isotopeof hydrogen, and hence only two of the three parameters requiredto fix the structure of the molecule have been supplied.Althoughthe C--H distance cannot be fixed with certainty, it very probably84 W. G. Penney, Proc. Roy. SOC., 1938 (in the press).35 N. Ginsburg and E. I?. Barker, J. Chem. Physics, 1935, 3, 668.36 P. Bartunek and E. F. Barker, Physical Rev., 1935, 48, 616HAWORTH : TRITERPENES.331This general scheme of origin of the products is also supported bythe identification of 2-hydroxy-1 : 8-dimethylpicene 27 from amyrin,and the assumption regarding the migration of the methyl group isstrongly supported by observations on some amyrin derivatives.34By Wolff reduction of the semicarbazone of amyrene (CO for CH*OHin 11), a hydrocarbon (111; R’ = R” = H) was prepared. Inaccordance with the hypothesis, 1 : 2 : 3 : 4-tetramethylbenzeneY1 : 2 : 5 : 6-tetramethylnaphthaleneY and phenolic compounds werenot produced by dehydrogenation of this compound, but 2 : 7-di-,1 : 2 : 5-, and 1. : 2 : 7-trimethylnaphthalenes and 1 : %dimethyl-picene were isolated. The dehydro-genation products of the compound(I11 ; R’ = Me ; R” = OH) were alsoA in agreement with anticipations ;HO*HC</)1 : 2 : 5 : 6-tetramethylnaphthalene (inthis case from rings A and B), 1 : 2 : 7- “’>n trimethylnaphthalene, and a new x picene homologue, probably 1 : 2 : 8-PV.) trimethylpicene, were obtained.OtherformulaeY35 e.g. (IV), consistent with the isoprene rule also supplya rational explanation of the dehydrogenation results.(b) Oxidative Degradation of Oleanolic Acid and Hederagenin.-This section will be confined to the behaviour of oleanolic acid andhederagenin towards oxidising agents, and the constitution of othertriterpenes will be deferred until later in the Report. Oleanolicacid, C30H4803,5* and hederagenin, C30H4,04,6* are mono- anddi-hydroxy-acids respectively, and esterification and hydrolysisexperiments indicate the tertiary character of the carboxyl groups.The acids contain a double bond, which resists catalytic reduction,but its presence is deduced from the formation of lactones36 andbromo-la~tones.~* 36 Although rigid proof is lacking, the acids areusually regarded as y8-unsaturated acids.Rings A and B.Important evidence concerning the structure ofthese rings has been obtained by oxidising derivatives in which thecarboxyl group is protected by ester or lactone formation.Oxidation of the methyl ester of hederagenin (V) with perman-ganate 37 yields the methyl esters of a hydroxy-keto-acid (VI) anda dibasic hydroxy-acid (VII) by oxidation of the secondary and theprimary alcoholic group respectively. When the methyl ester ofI vlu<I34 L.Ruzicka, H. Schellenberg, and M. W. Goldberg, Helu. Chim. Acta,35 Z. Kitasato, Acta Phytochirn., 1937, 10, (l), 199.313 Z. Kitasato and C. Sone, ibkl., 1932, 6, (2), 179.37 W. A. Jacobs, J. Biol. Chem., 1926, 88, 631.1937, 20, 791332 ORGANIC CHEMISTRY.hederagenin is oxidised with chromic one carbon atom iseliminated and a mixture of the methyl esters of a keto-acid,C2gH440, (VIII), and a dibasic keto-acid, C2gH,& (IX), is obtained.By oxidising the acids (VIII) and (IX) with hypobr~rnite,~~~ 39* 40the tribasic acids, C2gH4406 (X) and C28H2206 (XI) respectively,are obtained, the formation of (XI) involving the loss of oneadditional carbon atom. These and later results indicate a1 : 3-arrangement of the diol group, which must be present in aterminal ring (A), and necessitate the partial formulz given below.The synthetical product was identical with rubrene; it gave+-rubrene with acids, and yielded an oxide which evolved oxygenon heating.24 The intermediate compound (VIII), stereoisomericwith dihydroxydihydrorubrene,6* was converted into colourlessdehydrorubrene (IX) 9e 25* 26 by dehydration.An independent syn-thesis of rubrene has been effected by c. F. H. Allen and L.The reversible oxidation is, in itself, an argument in favour of (11) forrubrene. The formation of such colourless oxides is chaxacteristic ofbenzenoid compounds, and anthracene and diphenylanthracene exhibitreversible oxidation (C.Dufraisse a.nd M. Girard, Compt. rend., 1935, 201,428; C. Dufraisse and A. Etienne, ibid., p. 280; E. Willemart, ibid., p. 1201 ;1936, 202, 140).18 G. Schroeter, Ber., 1921, 54, 2242; L. I?. Fieser, J. Amer. Chem. SOC.,1931, 53, 2329; L. F. Fieser and E. L. Martin, ibid., 1935, 57, 1844.10 C. Dufraisse and M. Loury, Compt. rend., 1935, 200, 1673.2O C. Dufraisse and L. Velluz, Compt. rend., 1935, 201, 1394; Bull. SOC.21 A. Guyot and A. Haller, Bull. SOC. chim., 1904, 81, 795.chim., 1936, 3, 1905392 ORGANIC CHEMISTRY.Gilman,22 and the intermediate (VIII) obtained by these authors isidentical with dihydroxydihydrorabrene.CO CHPhCO PhThe formation of polynuclear hydrocarbons occurs frequentlywith meso-phenylnaphthacenes. The conversion of (VIII) into(IX) mentioned above provides one example, and 5 : 12-diphenyl-naphthacene is converted into the violet hydrocarbon (X) or theblue hydrocarbon (XI) by mild oxidation; (XI) is probablyidentical with a compound obta,ined previously from r~brene.~'.28Ph(IX.) (X.) (XI-)The new rubrene formula (11) gives a satisfactory explanation ofthe chemistry, and C. Dufraisse 3 has published a list of revisedformula for rubrene derivatives. One point, illustrated bydiphenyldichloronaphthacene, requires special comment. This sub-32 C. I?. H. Allon and L. Gilman, J . Arner. Chem. Soc., 1938, 58, 937.23 AUen and Gilman state that the diphenylnaphthacenequinone does notreact with phenylmagnesium bromide and therefore cannot be an intermediatein the Dufraisse synthesis.In a reply to this criticism (Bull. SOC. chim., 1936,3, 2175) it is pointed out that a large excess of the Grignard reagent isnecessary for the reaction.24 The oxides of naphthaceno and 5 : 12-diphenylnaphthacene do notevolve oxygen on heating; naphthacene oxide yields some 5-keto-5 : 12-dihydronaphthacene. The elimination of oxygen is facilitated by accumul-ation of meso-phenyl groups as in rubrene.?5 C. Dufraisse and L. Enderlin, Compt. rend., 1932, 194, 183.56 L. Enderlin, ibid., 1938, 202, 1188.27 C. Dufraisse and R. Girard, Bull. Soc. chim., 1934, 1, 1359.M. Radoche, Ann. China., 1933, 20, 200IIAWORTII : RUBRENES AND AZULENES. 393stance, readily obta,ined by the action of heat on (XII) 1i29 andpreviously represented on the basis of (I) by the planar symmetricformula (XIII), is now given the centro-symmetric formula (XIV).The latter formula is more in accordance with its conversion intothe violet (XV) 30 or blue (XI) compounds, by loss of one or twomolecides of hydrogen chloride respectively.c1 CPh CPh Ph C1(XII.) (XIII.) (XIV.)The new formula, however, still experiences a difficulty inexplaining the conversion of rubrene into 4-rubrene. The presenceof four meso-phenyl groups is essential for this reaction and it issuggested that these facilitate the addition of acid, HX, to the9 : 10-positions to give a compound of type (XVI), which isconverted into +rubrene (XVII) by loss of HX.3lPh C1 H Ph H Ph\-/(XV.) (XVI.) (XVII.)Several mechanisms for the formation of rubrene have beensuggested.39 22Axulenes.The blue colour of camomile oil was first observed in the fifteenthcentury, and since then it has been shown that, in about 20% ofthe cases investigated, essential oils contain or give rise to blue orviolet substances known as azulenes.1 I n general, the developmentof a blue colour in essential oils may be induced by dehydrogen-ation with selenium , sulphur, nickel or palladiurn-charcoal.2 Thepresence of azulenes or azulene-yielding compounds is detected byaQ C.Dufraisse and R. Buret, Compt. rend., 1932, 195, 962.30 C. Dufraisse, R. Buret, and R. Girard, Bull. SOC. chim., 1933, 55, 702.31 The oxidation of naphthacenequinone to naphthoic and benzoic acidsIt is therefore suggested Chat proves the 5 : 12-structure of the quinone.HX adds to the 5 : 12-positions.1 A.S. Pfau and P, Plattner, HeZv. Chim. Acta, 1936, 19, 858.2 L. Ruzicka, S. Pontalti, and F. Balas, ibid., 1923, 6, 855394 ORGANIC CHEMISTRY.the formation of' a blue-violet colour on the slow addition ofbromine to a chloroform or acetic acid solution of the essential 0i1.3In 1915, A. E. Shernda14 observed that the blue colour wasremoved from ethereal or petrol solutions of the oils by shakingwith concentrated phosphoric acid solution, from which theazulenes were regenerated by dilution with water. The azulenesobtained from cubebs, camphor or gurjun oils, yielded dark-colouredpicrates, and by titration of the picrate, the formula C,,H,, wasdeduced for the hydrocarbon from oil of cubebs.4~A large number of supposedly different azulenes have beenreported and named from their respective natural oils, but it nowappears that in reality only four or five isomeric and distinctsubstances are involved.S-Guaiacazulene, blue needles, m. p.30°,14 occurs naturally in geranium oil1** and in some coal tars.12It has been obtained by the action of sulphur on the sesquiterpeneor sesquiterpene alcohol fraction of the oils from guaiacum WOO^,^* 9callistris,1° patchouli,l gurjun balsam 1s ' 8 l1 and EucalyptusgZobuZus,l. and also by nickel dehydrogenation of gurjun balsamoi1s.l. l2 Camazulene, m. p. 132",l6 isolated from camomile andyarrow oils,'^ lactarazulene, a liquid recently l6 obtained from thefungus, Lactarizbs deZiciosus L., and vetivazulene, violet needles,m.p. 32",15 obtained by the action of sulphur on vetiver oil,l*15resemble S-guaiacazulene in properties. Elemazulene is obtainedin the form of a liquid in 1% yield by the action of selenium onelemol, a crystalline sesquiterpene alcohol of unknown structure.The product obtained from an essent.ia1 oil depends to some extenton the dehydrogenating agent and no azulene is obtained bytreating elemol with sulphur. A violet azulene previously knownas Se-g~aiacazulene,~ prepared by the action of selenium onguaiacum wood oil, has recently1*14 been proved a mixture ofazulenes from which S-guaiacazulene may be isolated.1920, p. 417.3 R. T. Baker and H. G. Smith, " k Research on the Eucalypts," Sydney,4 J .Amer. Chem. SOC., 1915, 37, 167, 1537.5 L. Augspurger, Science, 1915, 42, 100.6 R. E. Kremers, J. Amer. Chern. SOC., 1923, 45, 717.7 L. Ruzicka and E. A. Rudolph, HeZv. Chim. Acta, 1926,9, 118.8 P. Barbier and L. Bouveault, Compt. rend., 1894, 119, 281.9 L. Ruzicka and A. J. Haagen-Smit, HeZv. Chim. Acta, 1931,14, 1104, 1122.10 Y. Asahina and S. Nakanishi, J. P h m . Soc. Japan, 1932, 52, 1, 2, 5, 12.11 W. Treibs, Ber., 1935, $8, 1751.l2 J. Herzenberg and S. Ruhemann, Ber., 1925, 58, 2249; 1927, 60,13 J. Melville, J. Amer. Chem. Soc., 1933, 55, 3288.l4 K. S. Birrell, ibid., 1934, 56, 1248; 1935, 57, 893.15 A. St. Pfau and P. A. Plattner, Helv. Chim. Acta, 1937, 20, 224.2459 ; I?. Schlapfer and 0. Stadler, HeZv.Chim. Acta, 1926, 9, 185HAWORTH : RUBRENES AND AZULENES. 395The Sherndal method of isolation with phosphoric acid has beenextensively used, and the azulenes are characterised by picratesand styphnates, or better by the more stable and more highlycrystalline compounds with trinitrobenzene l6 or trinitrotoluene.Decomposition of the picrate and styphnate is effected withammonia, and the azulene is recovered from the trinitrobenzenecompound by reduction with ammonium sulphide, followed bydistillation with steam. Recently l5 the decomposition of thesepolynitro-derivatives has been improved by chromatographicadsorption on alumina; when cydohexane is used as solvent, theazulene derivative dissociates, the polynitro-compound is adsorbed,and the azulene is recovered from the filtrate in a very pure state.Catalytic reduction of the azulenes gives an octahydro-compound,C15H26,4 but refractivity measurements 7p suggest that theazulenes contain it dicyclic system with five double bonds, one ofwhich resists reduction.Oxidation of the azulenes with perman-ganate 6m gives acetic, isobutyric and ovalic acids and acetone, andozonolysis of the partly reduced azulenes (mainly tetrahydro-derivatives) 13* l4 yields formaldehyde, acetone, formic, isobutyricand a-rnethylglutaric acids. When the azulene-containing fractionsof vetiver or guaiacum wood oils are heated with hydriodic acidand red phosphorus, substances are produced which give smallyields of the naphthalene homologues (III) and (IV) whendehydrogenated with sulphur.The simplest explanation of theformation of (111) and (IV), which have been identified bycomparison with synthetic specimens,l7 would be to postulate aeudalene skeleton for the azulenes. This, however, is inconsistentwith the observations that fully reduced compounds of the eudesrnoltype, unlike decahydro-S-guaiacazulene, give naphthalenes but noazulenes on dehydrogenation.1 Oxidation of decahydroguaiac-azulene results in ring scission to a dibasic Cl5-acid, which onpyrolysis gives a CI4 ketone. Catalytic dehydrogenation of thisketone has furnished a, phenolic compound, thus indicating the16 H. Willstaedt, Ber., 1935, 68, 333; 1936, 69, 997.17 L. Rueicka, P. Pieth, T. Reichstein, and L. Ehmann, Ber., 1933, 66,268396 ORGANIC CHEMISTRY,presence of a seven-membered ring in the azuleiies.15 Thesuggestion is made that the naphthalene derivatives (111) and (IV)are formed from guaiacazulene (I) and vetivazulene (11) respectivelyby a retropinacolinic change, and structure (11) for vetivazulenehas been established by the synthesis of the phenol obtained bythe degrada,tion outlined above.lsThese suggestions are supported by the synthesis of a number ofcompounds of type (VIII).By ozonolysis of octalin, W. Hiickel,A. Gercke, and A. Gross l9 obtained the diketone (V), which wasreadily converted by aqueous sodium carbonate into the cyclo-pentenocycloheptanone (VI).20 A. S. Pfau and P. Plattriercondensed this ketone with Grignard reagents and dehydrogenatedthe products (VII) with nickel or sulphur to give the substitutedazulenes (VIII).The products (VIII; R f= Me, Et or Ph), isolatedR N n RW e ) (VI. 1 (VII.) (VIII * )by the phosphate method, were purified as picrates or thetrinitrobenzene compounds. Azulene, the parent hydrocarbon(VIII; R = H), was prepared l5 from (VI) by reduction, first tothe dihydro-compound and then to the carbinol, and the latter wasdehydrogenated with palladium-charcoal to ( V I I I ; R = H). Theyields of azulenes are about 5% and as they, particularly (J7111;R = H), are unstable to acids and air, the chromatographicprocedure is frequently employed in the decomposition of thepolynitro-derivatives. The synthetic compounds have an intenseblue colour, indistinguishable from that of S-guaiacazulene in dilutealcoholic solution and a comparison 1 5 3 21 of the absorption spectrabetween 2300-7500 A.suggests that azulene, S-guaiacazulene, andvetivazulene belong to the same class. Consequently vetivazuleneand S-guaiacazulene are regarded as 4 : 8-dimethyl-2-isopropylazulene(11) and 1 : 4-dimethyl-7 -isopropylazulene (I) respectively.The occurrence of this cyclopentane-cycloheptane system in theterpene family is of great interest.22 The famesol chain can beThe experimental details of the degradation of khe azulenes to, and thesynthesis of, these phenols have not yet been published.Is Ber., 1933, 66, 563.80 W. Huckel and L. Schnitzspahn, AnnaZen, 1933, 505, 2742 1 B. Susz, A. S. Pfau, and P. A. Plattner, Helv. Chim. Acta, 1937, 20, 469.33 The occurrence of azulenes, as such, in fungi or essential oils has notbeen definitely established ; they may be produced during extraction 16 (seealso Chem. Zen&., 1934, I, 81)IIAWORTH : RUBRENES AND AZULENES. 397arranged so as to give nine structures of the cyclopentane-cyclo-heptane type and vetivazulene (11) and guaiacazulene (I) representtwo of these forms.Azulenes may be obtained from sources other than the terpenes.The blue distillate reported by W. Hentzschel and J. Wislicenus 23as a by-product during the preparation of cyclopentanone bydistillation of calcium adipate, contains azulene, which has beenidentified spectro~copically.1~ The production of azulene in thisreaction is probably due to traces of impurity which facilitatedehydrogenation and it has been shown that the addition of nickelassists the azulene formation. The ketone (VI) is probably formedby the route outlined below, and converted into (VIII; R = H),[CH214*CO&Adipjc acid --+ CO --t\[CH2],*C02Hby the action of traces of nickel or impurities ; it has been shownthat (VI) is partly converted into (VIII; R = H) with selenium orpalladium-carbon . R. D. H.L. 0. BROCKWAY.R. D. HAWORTH.R. P. LINSTEAD.T. G. PEARSON.S. PEAT.T. W. J. TAYLOR.2:i Annalen, 1893, 275, 312

ISSN:0365-6217    

DOI:10.1039/AR9373400196

出版商:RSC    

年代:1937

数据来源: RSC

摘要:

BIOCHEMISTRYAT the present time biochemistry is passing through a fruitfulperiod, in fact many will say that biochemistry is now fulfilling itspromise and is helping materially to solve a few of the more complexproblems of medicine. The study of the chemistry of the vitaminsis in some cases almost complete, and the advances made duringthe past fern years can be described as little short of miraculous.Ten years or so ago it would have been extremely difficult to findanyone bold enough to suggest that at the beginning of 1938 weshould know the chemical constitution of many of the importantvitamins and have available synthetic preparations of a t leastthree of them. For practical purposes, the use of the pure naturalor synthetic vitamins is, of course, very limited (under peace-timeconditions a t least), but for the study of their physiological functionsand for the further investigation of dietetic problems, these pureproducts are of considerable value.The year 1937 has witnessed many important advances in ourknowledge about the vitamins.Of special interest might be men-tioned further syntheses of vitamin B,, the reported synthesis ofvitamin A,, the isolation from naturaJ sources of other vitamins ofthe D group, the partial clarification of the story about the vitaminB,-complex, distinct adTances in our knowledge about the chemistryof vitamin E, and the demonstration that vitamin C-deficiency isoften associated with a diminished resistance of the body to certaintypes of infection.Carbohydrate metabolism has been the subject of intensiveinvestigation in many parts of the world, and if no particularlyoutstanding advance can be mentioned, the results obtained willundoubtedly help towards a clearer understanding of this complexproblem.The views about the chemistry of muscle contractionhave certainly become more complicated during recent years, butthere is now hope that before long it will be possible to present adefinite and universally accepted general scheme to explain whathappens when a muscle fibre is stimulated and caused to contract.In chemotherapy there has been real progress, and the discoveryin 1935 of the value of the prontosil drugs has been followed by avery fruitful attack on this problem during the past two years.The less complex drug sulphanilamide, and some related compoundswhich are still more active, are proving of inestimable value for thetreatment of certain diseases, and here we can record what iWORNALL: ANIMAL.399probably the most important advance in chemotherapy for manyyears. Another noteworthy piece of work is that of H. King,E. M. Louie, and W. Yorke on the trypanocidal action of guanidinesand related compounds, an investigation which gives much promisein connection with the treatment of sleeping sickness.l n a short review of the progress of biochemistry it is naturallyimpossible to discuss more than a very small fraction of the wholefield, but in the review next year it might be possible to fill in someof the gaps. The use of deuterium and radioactive phosphorus inthe study of metabolism, and recent developments in connectionwith hormones and anti-hormones, proteins, enzymes, and thechemistry of iinmufiity have all had to be omitted from this sectionthis year.In particular it is regretted that it is not possibleto discuss here the important discoveries about the action ofprotamine-insulin, and the influence of zinc on the action of thiscompound, ordinary insulin and certain other hormones.Considerations of space have again necessitated the inclusion ofonly certain selected subjects in the Plant Biochemistry section.In view of the fact that in the last few years various aspects of thebiochemistry of the higher plants have predominated in theseR'eports, it is felt that developments in the chemistry of certain ofthe smaller organisms should be placed on record.Several yearshave elapsed since reference was made here to some of these organ-isms, and in these cases the period under review has been extendedaccordingly. The wide interest in recent inveatigations of plantvirus, and the demonstration by Stanley and others of the funda-mental chemistry concerned, demands consideration this year.1. ANIMAL BIOCHEMISTRY.The Vitamins.Vitamin A.-H. N. Holmes and R. E. Corbet have described theseparation, from certain fish liver oils, of crystalline vitamin Ain pale yellow needles, m. p. 7.5-8-0". This preparation has anextinction coefficient of 2100 and a biological assay value of 3,080,000international units per g.Analysis gives C, 83.28 ; H, 10-44%, andthe mol. wt., as determined by the freezing point depression, is294 (Karrer's formula for the vitamin requires C, 83.84 ; H, 10.56% ;mol. wt., 286).The synthesis of vitamin A has a t last been reported, this havingbeen effected from 13-iononesemicarbazormee by R. Kuhn andC. J. U. R. Morris? The identity of the synthetic product withScience, 1937, 85, 103; J. Arner. Chem. SOC., 1937, 59, 2042.Ber., 1937, 70, 853400 BIOCHEMISTRY.the natural vitamin has been shown by the mixed chromatographicadsorption test on alumina and growth tests on rats.The suggestion that a second -A exists ha’s been made by twogroups of workers. A. E. Gillam, I. M. Heilbron, E. Lederer, andV. Rosanova,3 and J. R.Edisbury, R. A. Morton, and G . W.Simpkins 4 have independently shown that in antimony trichloridesolution certain liver oils show an additional band near 6930 A.According to the latter group of investigators, this 6930 A. chromogen(designated vitamin A2) is present in halibut liver oil, but rarelyin cod liver oil and never in whale liver oil. There is apparently,as yet, no evidence as to the biological activity of this allegedsecond vitamin A.Amongst other work on this vitamin might be mentioned thatof T. Moore,5 who has determined the -A content of adult humanliver. In health the “ median ” value is found to be 220 internat.units per g. of wet tissue, whereas lower values are found in mostdiseases. The vitamin A content of the liver a t birth is very low,but it rises sharply in the earliest months and reaches a more orless static level during what would be, in normal circumstances,the later stages of lactation.6 In the latter investigations on thelivers of children under 15 years of age dying by accident or fromdisease, low liver vitamin A reserves were associated with deathfrom pneumonia, septic diseases, and heart diseases, but not acuteinfectious diseases. In general the results were in agreement withthose obtained in the study of the livers of adult^.^ The r6le of theliver in the vitamin A economy of the hen is essentially the sameas in the mammal, for administration of cod liver oil, or of avitamin A concentrate, to laying hens led to the accumulation ofthe vitamin in the liver.The vitamin A content of the eggs wasalso increased, but returned to normal when the cod liver oil treat-ment ceased, although the liver reserves were sufficient to maintainthe A content of the egg a t the raised level for about 300 ovulation^.^E. Mellanby has shown that vitamin A deficiency in young dogsproduces degenerative changes in the ganglia, nerves, and organs of’both hearing and balance inside the temporal bone. The “in-attention ” of dogs fed on these deficient diets, previously ascribedto cerebral defects, is undoubtedly due to deafness, and attemptsare being made to determine whether certain forms of deafness inman can be explained in a similar manner.Natwe, 1937, 140, 233. Ibid., p. 234.li Biochem. J . , 1937, 31, 155.6 J.B. Ellison and T. Moore, ibid., p. 165.33. M. Cruickshank and T. Moore, ibid., p. 179.Chem. and Ind., 1937, 56, 1054WORMALL ANIMAL. 401Vitamin Bl (Aneurin).-The synthesis of aneurin by R. R.Williams and J. K. Cline was mentioned last year.Q Early this yeari~ similarly successful attack on this problem, by a different method,was described by A. R. Todd and F. Bergel’lo the synthetic materialproving to be identical, as far as chemical and biological tests areconcerned, with the natural vitamin. Another synthesis has beendescribed by T. Hoshino and M. 0hta.ll The relationship betweenthe structure of aneurin and its physiological activity has beenstudied by F. Bergel and A. R. Todd.12 These authors preparedand examined the biological activity of five analogues of aneurinand were able to reach certain general conclusions as to the groupswhich are essential for vitamin B, activity.The determination of vitamin B, by chemical methods has beenstudied by several authors, for it is well recognised that a chemicalmethod would greatly facilitate many of these investigations.B.C . P. Jansen l3 described a method which involves the conversionof the vitamin into thiochrome and the determination of the latterby measuring the fluorescence with a photoelectric cell. Thismethod has been modified by W. Karrer and U. Kubli,14 J. Goudsmitand H. G . K. Westenbrink l5 and by M. A. Pyke.16 The last-named author finds that the method can be applied to a widerange of materials (milk and other foodstuffs, animal tissues andurine), although it is necessary to take special precautions in manyinstances.For the determination of the vitamin B, content ofurine it is necessary to concentrate it by adsorption on fuller’s earth.Another method which promises to be of considerable value is thatof W. H. Schopfer,17 a modification of which is described by A. P.Meiklejohn.ls The method depends on the growth-promoting effectof the vitamin on a mould, Phycomyces BZaEesZeeanus, and deter-minations can be made 011 small amounts of blood (e.g., 1-3 ml.).All workers are agreed, however, that this test is only applicable toactive concentrates and not to ordinary food materials or extracts.A fermentation test, which depends on the measurement of theaccelerating power towards the fermentation of glucose by Fleisch-mann yeast and is capable of detecting 10‘6 g.of natural or syrrtheticvitamin B,, is suggested by A. Schultz, L. Atkin, and C. N. Frey.19The “ bradycardia ” method 2o for vitamin B, determinations has9 Ann. Reports., 1936, 33, 381; cf. also J. K. Cline, R. R. Williams, and10 J., 1937, 364. l1 Proc. Imp. Acad. Tokyo, 1937,13, 101.12 J., 1937, 1504. Rec. Trav. china., 1936, 55, 1046.14 Helv. Chim. Acta, 1937, 20, 369. l5 Nature, 1937, 139, 1108.16 Biochem. J., 1937, 31, 1955. l 7 Hull. SOC. Chim. b i d . , 1935, 17, 1097.18 BiocJzein. J . , 1937, 31, 1441. l9 J . Airier. Chena. soc., 1937, 59, 948.20 T. W. Birch and L. J. Harris, Biochem. J., 1934, 28, 602.J. Finkelstein, J.Amer. Chem. Soc., 1937, 59, 1052402 BIOCHEMISTRY.been subjected to a careful reinvestigation by P. C. Leong andL. J. Harris.21 Three crystalline specimens of natural and one ofsynthetic vitamin Isl were used for the assays, and all showedapproximately the same activity (2.9 x 10-6 g. of crystallinevitamin B, hydrochloride per one I.U.). A statistical analysis ofthe results of a large number of tests shows that the accuracy ofthe method is such that the probability is 21/22 that the meanresult will be within & 22% of the true value when five " tests "are made, or within & 12% for twenty tests, each test being onedose given on one occasion to one rat.Studies on the relationship between vitamin B1 and oxidationprocesses in brain have been continued by R.A. Peters and hiscolleagues. Further investigation has shown that the action of thevitamin is related specifically to pyruvic oxidase in its aerobicreaction and the reaction can be represented as follows : 22Lactate + 0 j Pyruvate + (n)O _jr Oxidation productsZ t t Pyrophosphate (n = 4) Vitamin B,Measurements of the R.Q. and the oxygen/pyruvate ratio forpigeon brain indicate that the oxygen consumption is only aboutfour-fifths of that needed to oxidise all the pyruvate. The pro-duction of carbon dioxide is lo% in excess of that required forcomplete combustion, and it is suggested that one molecule ofpyruvic acid out of five disappears by some channel other thancomplete 0xidation.~3 The pyruvate burned does not appear toundergo conversion into succinic acid, a-ketoglutaric acid or aceto-acetic acid, and the pigeon brain " pyruvate oxidase " system, ofwhich vitamin B1 is a constituent, is not a general ~t-keto-oxidase.~~Amongst other work on vitamin BI, the discovery of K.Lohmannand P. Schuster25 that co-carboxylase is a &phosphoric ester of21 Biochem. J . , 1937, 31, 672.22 R. A. Peters, ibid., 1936, 30, 2206; Deutsche med. Woch., 1937, 63, 1144;Chem. Weelcblad, 1937, 34, 442. This theory suggesting a relationship betweenvitamin B, and pyruvate oxidation receives valuable support from the obser-vation of B. S. Platt and G. D. Lu (Pvoc. Chinese Physiol. SOC., 1936, 16;Quart. J. Med., 1936,5, 355) that in patients suffering from beri-beri there is amarked increase in the bisulphite binding substances (mainly pyruvic acid)in the blood and other body fluids. This increase appears to follow the degreeof vitamin B, deficiency.R. H. S. Thompson and R. E. Johnson (Biochem. J.,1935, 29, 694) have obtained similar results in determinations on the blood ofB,-avitaminous pigeons and rats.23 G. K. McGowan, Biochem. J., 1937,31, 1627.24 G. K. McGowan and R. A. Peters, ibid., p. 1637.Naturwiss., 1937, 25, 26; cf. also H. von Euler and R. Vestin, ibid.,p. 416. K. G. Stern and J. W. Hofer, Science, 1937, 85, 483WOR,MALL : ANIMAL. 403aneurin is of outstanding importance, and this discovery, togetherwith the above-mentioned work of the Oxford school on the partplayed by vitamin B, in brain oxidation, should throw much lighton the physiological r61e of this vitamin.The suggestion ofK. Lohmann and P. Schuster that pyruvic acid accumulation inthe experiments on avitaminous pigeon's brain is due to lack ofco-carboxylase has been tested recently by R. A. Peters,26 whofinds that, although vitamin B, may act as the diphospho-compoundin brain, the other components of the system are dissimilar fromthose of yeast.27Vitamin B, (Complex) .-There is much confusion in the literaturerelating to the vitamins of the I3 group, and it seems probable thatthis state of affairs will continue unti! we know the precise natureof all the components of this complex. Until this happens, it willprobably be wiser to group together the members of the B grocp,other than vitamin B, (aneurin), under the heading vitaminB,-complex.28Space will not allow a full review of literature on this subject,but it will probably be agreed by most authorities in this field thatthe position is a little clearer as a result of the work of the past year.The vitamin B,-complex appears to consist of at least three factors :(1) LactoAavin(2) Vitamin B, (" rat-pellagra '' or rat-antidermatitis factor)(3) Pellagra-preventing (or anti-black-tongue) factor.A considerable amount of evidence has been presented duringrecent years in support of the view that nicotinic acid (or its amide)enters somewhere into the vitamin 3,-complex. Various authorshave shown that this substance has a growth-promoting action forcertain micro-organisms29 or for pigeons or rats fed on a dietdeficient in part of the B,-complex.s C.A. Elvehjem, R. J. Madden,E'. M. Strong, and D. W. Woolley31 have shown that nicotinic acidcan cure " black-tongue " in dogs and this suggestion that the P-Pfactor and nicotinic acid are closely related, if not identical, hasreceived strong support from the recent work of L. J. Harris. Thisauthor finds that monkeys resemble human beings and dogs (and9;6 Biochem. J., 1937, 81, 2240.2 7 K. Lohmann and P. Schuster (Biochem. Z., 1937, 294, 188) have alsoreached the conclusion that the brain system differs from yeast carboxylase.28 Cf. L. J. Harris, Biochem. J., 1937, 31, 1414.29 B. C. J. G. Knight, ibid., pp. 731, 966; E. R. Holiday, ibid., p. 1299;30 C.Punk and I. C. Funk, J . Biol. Chem., 1937, 119, Proc. XXXV; D. V.s1 J. Amer. Chem. SOC., 1937, 59, 1767.J. H. Mueller, J . Biol. Chem., 1937, 120, 219.Frost and C. A. Elvehjem, ibid., 1937, 121, 265404 BIOCHEMISTRY.thus differ from rats) in requiring a factor of B, other than lacto-Aavin and vitamin B,, and this factor appears to be identical withthat which prevents pellagra in man and black-tongue in dogs.28This nutritional failure in monkeys can be cured by nicotinic acid,and this acid also produces a dramatic improvement in the con-dition of human beings suffering from pellagra.32 The suggestionis made that nicotinic acid (or its amide) may be either the P-Pvitamin itself or the less active form, or “ precursor” of a moreactive variation of the P-P vitamin, which could be formed from itin the animal body.Amongst other evidence in favour of the view that vitamin B, isof a ‘‘ tripartite ” nature, is that presented by C.E. Edgar andT. F. Macrae, who find that autoclaved yeast contains two factorswhich are required to give optimum growth of rats fed on avitamin B-deficient diet plus lactoflavin and vitamin B1.33 Thesame aut’hors 34 find that one of these factors (that present in filtratesafter exhaustive extraction of the yeast extract with fuller’s earth)appears to be distinct from vitamin B,, but is perhaps identicalwith the “filtrate factor ” from liver extracts described byS. Lepkowsky and his ~olleagues.3~ Neither nicotinic acid noriiicotinamide can, however, replace this yeast filtrate factor.36Vitamin C.-Investigations in this field have been mainly con-cerned with studies on the behaviour of ascorbic acid and relatedcompounds in the body, and the relationship between this vitaminand infection.Numerous papers z7 have been published describingthe determination of ascorbic acid in blood, urine, and tissues by amodification of the method of L. J. Harris and S. N. Ray38 or byother methods. The use of these chemical methods has undoubtedlyled to a clearer understanding of the minimum body requirementsas far as this vitamin is concerned, but its exact physiological r61eis still not clear. There is, however, a considerable amount ofevidence that ascorbic acid may have a specific function in enablingthe body to resist certain infections, and with a continuation ofthe present mass attack on this problem in various laboratories and32 Report of a lecture by L. J.Harris, Lancet, 1937, ii, 1467.33 Biochenz. J., 1937, 31, 88G.34 Ibid., p. 893.36 T. 3’. Macrae and C. E. Edgar, Biochetn. J., 1937, 31, 2225.37 P. Manceau, A. A. Polioard, and M. Ferrand, BulE. SOC. Chin~. biol.,1930, 18, 1623; W. Tschopp, Z. physiol. Chern., 1936, 244, 59; R. R. Musulinand C. G. King, J . Biol. Chem., 1936, 116, 409; F. Widenhauer, Kliiz. Woch.,1936,1& 94; R. FerrsLri rtad G. Buogo, A~ch. Pisiol., 1935,35, 125; A. Bujitanud T. Ebihara, Biockcin. z., 1937, 290, 172, 182, -192 ; P. &!kxmier, Bull. Soc.Chine. bwl., 1937, 19, 877.38 Lancet, 1935, i, 71.36 Ann.Reports, 1936, 33, 385WORMALL : ANIMAL. 405hospitals it should not be long before thc relationship betweenvitamin C-deficiency and a decreased immunity can be defined moreprecisely.There is still some disagreement as to whether the 2 : 6-dichloro-phenol-indophenol method gives a true estimate of the vitamin Ccontent of urine, blood, etc., but the same charge of non-specificitycan probably be made against the other methods.C . Mentzer and A. Vialard-Goudou39 claim that the methyleiie-blue method 40 is more specific than the 2 : 6-dichlorophenol-indophenol method, but L. J. Harris*l considers that the lattergives reliable results and that compounds containing SH groups donot interfere in practice, provided that suitable experimentalconditions are observed. A spectrophotometric determination ofascorbic acid in tissues is described by A.Chevallier and Y. Choron,4%who suggest that it, permits the detection of 0.01 mg. of the vitamin.M. Srinivasan,43 using a modification of the method of H. Tauberand I. S. Kleiner,44 has utilised an ascorbic acid oxidase for thedetermination of this vitamin in certain natural sources andconcludes that the lower values obtained are more accurate thanthose previously recorded.Some doubts have been expressed as to the exact nature of thereducing substance present in urine which is determined as vitamin C .Identscation by biological tests will be very difficult or may evenbe impossible (because of the small amount, and possibly on accountof toxic substances which may be present), but isolation andidentification by chemical means appear to offer no insuperabledifficulties.K. Hinsberg and R. Ammon45 failed, however, toisolate from normal urine the 2 : 4-dinitrophenylhydrazine derivativeof dehydroascorbic acid, and concluded that urine cannot containmore than about one-third of the amount of ascorbic acid indicatedby titration with 2 : 6-dichlorophenol-indophenol. C. P. Stewart,H. Scarborough, and P. J. Drumm 46 have more recently succeededin this quest, and have isolated from 12 litres of normal urine 20 mg.of the pure 2 : 4-dinitrophenylhydrazine derivative.T. Meuwissen and E. Noyens 47 have made similar observations,3O Bull. Xoc. Chim. biol., 1937, 19, 707.40 Cf. R. Ammon and K .Hinsberg, Klin. Woch., 1936, 15, 8 5 ; E. Trier,Ugeskr. Lceger, 1936, 98, 1238; C. Mentzer, Compt. rend. SOC. Biol., 1937,125, 330.4 1 Proc. 5th Intern. Cong. Tech. Chem. Agric. Ind., Holland, 1937, I, 112.42 Bull. SOC. Chim. biol., 1937, 19, Fill.43 Biochem. J . , 1937, 31, 1521.4 5 Biochem. Z., 1936, 288, 102.4 6 Nature, 1937, 140, 282; Biochem. .J., 1937, 31, 1874.4 7 Cited from ref. (46).44 J. Biol. Chem., 1935, 110, 559406 BIOCHEMISTRY.and there appears to be no doubt that ascorbic acid is normallypresent in ~rine.~8B. C. Guha and B. Ghosh 49 claim t o have cor&rmed their earlierobservation that rat tissues in a closed volume of air can synthesiseascorbic acid from mannose, and the negative reqults of otherauthors 50 are attributed to the fact that no synthesis can be detectedin nitrogen.J. R. Hawthorne and D. C. Harrison 51 have, however,failed to confirm this synthesis from mannose in minced rat liverincubated with Ringer-phosphate solution in the presence of oxygen ;in addition there was no increase in the vitamin C content of thelivers of rats as a result of the subcutaneous or intravenous injectionof mannose.The vitamin C requirements of man have been determined byvarious workers and the average figure usually given as about60 mg. per 70 kg. 111811.5~ P. H. O’Hara and M. N. Hauck found that2200-2800 mg. are required, at the rate of 200 mg. daily, to saturatethe tissues after feeding a deficient diet for a month, and theirresults indicated a maximum C reserve of 2500-3000 mg.53Administration by mouth may not, however, be completely satis-factory in investigations of this type, since it cannot be certainthat all the ingested vitamin is absorbed. For this reason theobservations of P.Schultzer 54 are of special interest. This authorgave a daily intravenous injection of 40 mg. of ascorbic acid to ascorbutic male adult, and found that the scurvy was cured andsaturation with ascorbic acid produced within 23 days, i.e., afteringestion of a total quantity of only 0-83 g. For satisfactory evi-dence about the reserves and the requirements of man with respectto vitamin C, it appears probable that this method of administrationwill have to be adopted, although it should not be overlooked thatfor practical purposes the information obtained from experimentswhere the vitamin is administered by mouth will be of more value.As a result of the accumulation of a large amount of evidence itseems certain that in many diseases the body is in a state of “ uii-saturation” in regard to vitamin C , although the intake may benormal or even completely adequate for healthy individuals.Whathappens to the ascorbic acid in the unhealthy is not known, but48 E. Gabbe (Klin. Woch., 1936, 15, 292) suggested that several forms ofvitamin C exist in urine, but this view has not received general acceptance.40 Nature, 1936, 138, 844. 6o Ann. Reports, 1936, 33, 387.Biochem. J . , 1937, 31, 1061.52 M. Heinemann, ibid., 1936, 30, 2299; M. Van Eekelen, ibid., p. 2291.63 J .Nutrition, 1936, 12, 413. 54 Biochem. J., 1937, 31, 1934.66 I;. J. Harris. A chapter in “ Perspectives in Biochemistry.” Editedby J. Needham and D. E. Green. Camb. Univ. Press. 1937; cf. alsorefs. 56 and 57WORMALL : ANIMAL. 407the extra consumption may be associated with the activity of theleucocytes. The early investigations arose primarily as a result ofthe observation that individuals whose diet contains a subnormalamount of vitamin C are more susceptible to certain infections, eventhough the deficiency may not be sufficient to produce scurvy.Several possible explanations of this loss of immunity can be offered,e.g., the vitamin may neutralise toxins produced by the organismsor it may play a part in the development of specific anti-bodies orof some non-specific system such as complement. This problemhas not j7et been solved, but it is not unlikely that further inves-tigation will yield results of real value in connection with immunologyand the treatment of disease.The association of a deficiency in the vitamin C intake and anincreased tendency towards infection has been observed too fre-quently to be entirely fortuitous, but it has still to be definitelyestablished that the increased usage of the vitamin in these infec-tions is not simply a result of metabolic disturbances caused by theinfection (ie., purely a secondary process).Successful results havebeen claimed, however, by many investigators following the treat-ment of certain infections with massive doses of the vitamin, and inaddition, it has been stated that periods of ill-health and epidemicshave occurred in certain countries a t a time when fruit andvegetables were not readily available.Irrespective of the questionof the exact relationship between vitamin C intake and resistanceto infection, there is thus ample justification for the advocation ofan increase in the amount of fresh fruit and vegetables to thosesuffering from certain infections. It is not possible in this reviewto quote all the work which has been carried out in this connection,but the reader will find more comprehensive surveys el~ewhere.~5As typical examples of the experiments which have been made, thework of L. J. Harris and his colleagues will be mentioned. Theseauthors have shown that osteomyelitis, in common with manyother infective conditions, causes a diminished rate of excretion ofvitamin C in the urine and a lowered response to a test dose, indi-cating an apparently increased usage of the vitamin.When thepatient is healed, he returns to normal in his usage of the vitamin.56Studies on pulmonary tuberculosis have shown that in this con-dition the deficit in vitamin C is seen in an extreme form, with agood correlation between the severity of the case and the diminutionof the urine titres.57 The suggestion is made that extra provisionof the vitamin should be made for all tuberculous patients. The56 1%. A. Abbasy, L. J. Harris, and N. Gray Hill, Lancet, 1937, 233,177.67 M. 4. Abbasy, L. J. Harris. and P. Ellman, ibid., p.181408 BIOCHEMISTRY.same authors s7 and other workers 58 have found that rheumatoidarthritis is also associated with a decreased vitamin C exmetlion anda lowered state of saturation. For the solution of this complexproblem relating to infections, a considerable amount of statisticalinformation will be required, but the task of collecting this materialwill probably be made easier by the simplified procedure for thevitamin-C urine test devised by L. J. Harris and M. A. A b b a ~ y . ~ ~It has been shown 56p 59r 59a that there is a very close parallelismbetween the dietary intake of the vitamin and its output in theurine, relatively little variation being seen between differentindividuals on the same diet. The reputed minimum intake (whichhas been determined by the amount needed to protect against anytendency to increased capillary fragility, or to cure symptoms ofincipient scurvy in mariners) is generally accepted to be about 25mg.per day. Now, this intake causes an excretion of 13 mg. perday, and it seems justifiable therefore to argue 56* 59u that, if asubject excretes less than this amount, he is “ below standard ”-not necessarily showing any clinical symptoms of deficiency, butnone the less probably not enjoying full, optimum health. Manyclinical trials have in fact shown that health is improved whenextra fruits and vegetables are included in the diet, %nd surveysbased on an analysis of urine have indicated that many workingclass subjects excreted less than the standard amount of thevitamin 59b just as an examination of national diets 5 9 ~ suggestedthat a subnormal intake was of common occurrence.The satisfactory results following administration of syntheticascorbic acid to individuals suffering from scurvy were reported bymany authors 6O very shortly after the synthesis of the vitamin wasfirst accomplished.In a very recent paper A. Elmby and E. War-burg 61 state, however, that three of their scorbutic patients failedto respond to the administration of ascorbic acid by mouth or byintravenous injection. A cure was effected, and the blood ascorbicacid was raised to a normal figure, by the administration of lemonjuice, and it is suggested that some other factor (a co-vitamin) isrequired for the absorption and retention of the vitamin.Thehypothesis that this factor is vitamin P is being investigated.Med., 1936, 35, 347; J. F. Rinehart, Ann. Intern. Med., 1936, 9, 671.6 8 J. F. Rinehart, L. D. Greenberg, and P. Baker, Proc. SOC. Exp. BioE.69 Lancet, 1937, 233, 1429.59a M. A. Abbasy, L. J. Harris, S. N. Ray, and J. R. Marrack, ibid., 1935,jg* L. J. Harris, M. A. Abbasy, and J. Yudkin (with a note by S. Kelly),59c J. B. Orr, “ Food, Health, and Iizcome,” Macmillan and Co., 1936.6o Ann. Reports, 1934, 31, 332.ii, 1399.ibid., 1936, i, 1488.61 Lancet, 1937, 233, 1363WORMALL : ANIMAL. 469Vitamin D.-Investigations carried out during the past few yearshave shown that several compounds possess antirachitic powers,and to the original vitamin 13, (calciferol) we must add several othermembers of this group.At the same time, the existence of severalprecursors of " vitamin D '' has been established. The position upto the end of last year was fully reviewed in the Annual Reports.G2Since then the search for substances having antirachitic propertiesand for substances which become active on irradia'tion or othertreatment has continued.F. Schenk 63 has isolated crystalline vitamin D, (mentioned lastyear) by hydrolysis of the m-diiiitrobenzoate ; the product hasm. p. 82-84", [%]To + 83.3' in acetone and maximum absorptiona t 2650 A. It resembles vitamin I), in giving a yellow colour withantimony trichloride and possesses an antirachitic potency equal tothat of D,.No antirachitic product other than vitamin D, couldbe isolated from halibut liver 0il.6~ A. Windaus and G. Trautmann,65starting from 22 : 23-dihydroergosterol, have obtained crystallinevitamin D, (m. p. 107-lo$', [a]:*" + 89.3" in acetone), with amaximum spectrum absorption value the same as that for vitaminAmongst the search for pro-vitamins should be mentioned theinvestigations of A. Windaus and F. Bock,66 who find that the pro-vitamin D of skin, isolated from the crude sterols of skin by adsorp-tion on alumina and fractional elution, is 7-dehydrocholesterol.Pigskin, which contains up to 5.9% of the pro-vitamin, is the richestsource encountered in this investigation. J. C. Eck, B. H. Thomas,and L. Yoder G7 have studied the chemical activation of sterols andfind that cholesterol (ordinary and purified), cholesteryl chloride,cholesterilene, dicholesteryl ether, cholestene and cholesteryl butylether are all activated by heating a t 85-90' with sulphuric acidand acetic anhydride in acetic acid, yielding it product of the sameantirachitic potency ; this product is, however, not derived from thepro-vitamin D of ordinary cholesterol, the substance which is con-verted into an antirachitic agent on irradiation.Further inves-tigations by J. C. Eck and B. H. ThomasG8 have shown thatcholesterol and cholesterilene can be rendered antirachitic by heatingwith a variety of reagents.F. W. Anderson, A. L. Bacharach, and E. L. SmithG9 havepresented revised specification values for pure calciferol (in.p. 1 16"D2.62 Ann. Repoyts, 1936, 33, 349, 390.64 H. Brockmann, 2. physiol. Chem., 1937, 245, 96.Ibid., 1937, 247, 185.6 7 J . Biol. Chem., 1937, 117, 655.I39 Analyst, 1937, 62, 430.1 3 ~ Naturwiss., 1937, 25, 159.6 6 Ibid., 1937, 245, 168.6 8 Ibid., 1937, 119, 621, 631410 BIOCHEMISTRY.(& lo), [cx]i9i1 3- 123*25-125*75” in ethyl alcohol (4% wt./vol.),E:& 2650 A. 460-500), and report that the biological activity ofeleven blends varied from 35.7 t o 45.0 internat. units per 10-6 g.The line-test assay for vitamin D, and the effect of different rachi-togenic diets on the intensity of the rickets and the response toantirachitic treatment, have been studied by A. L. Bacharach andhis c~lleagues.~OThe seasonal variation in the vitamin D content of cow’s milk hasbeen studied by J.E. Campion, K. M. Henry, S. K. Kon, andJ. Ma~kintosh,~~ who found that the direct exposure of the cow tosun- and sky-shine contributes all, and the pasture none, of theincrease in vitamin D potency of milk which takes place in thesummer.R. Nicolaysen 72 has carried out extensive investigations on themode of action of vitamin D. The results seem to indicate that theaction of this vitamin in the gut of the rat is confined to a direct actionon the absorption of calcium, and the well-known reduced absorptionof phosphorus in vitamin D deficiency is due to precipitation by theincreased amount of calcium in the bowel. The rate of absorptionof calcium from isolated loops of the small intestine increases withincreasing concentration in both normal and vitamin D-deficientrats, but the rate is lower with the latter than it is with normalrats.No difference was observed in the case of intestinal absorptionof xylose and sodium sulphate, nor was there any difference betweennormal and vitamin D-deficient rats as far as absorption of calciumfrom the abdominal cavity is concerned. The suggestion that theinfluence of vitamin D on phosphate absorption is merely a secon-dary effect is supported by the finding that isolated loops of thesmall intestine of normal and vitamin D-deficient rats are equallyeffective in absorbing potassium phosphate and sodium glycero-phospha,te.Vitamin E.-The isolation by H. 3%. Evans, 0. H. Emerson, andG .A. Emerson of substances which they named c c tocopherols ” andwhich had the formula C,9H,,0, from the unsaponifiable fraction ofwheat germ oil, and the possession of vitamin E activity by a-tocopherol, and to a lesser extent by P-tocopherol, were reportedlast ~ e a r . ~ 3 The authors have isolated the same products from cottonseed oil concentrate^,^^ and this work has undoubtedly stimulatedinterest in the relationship between the tocopherols and vitamin E.70 A. L. Bacharach, E. Allchorne, and H. E. Glynn, Biochem. J., 1936, 30,71 Biochem. J., 1937, 31, 81.73 Ann. Reports, 1936, 33, 392.74 0. H. Emerson, G. A. Emerson, and H. M. Evans, Science, 1936, 83, 421.2004; A. L. Bacharach, 2. Vitaminforschung, 1937, 6, 129.i B Ibid., pp. 107, 122, 323, 1086WORMALL : ANIMAL.41 1One significant difficulty in recognising a-tocopherol as Dhe purevitamin (or the more active of two vitamins) is the fact thai it is lesspotent in biological tests than was a similar preparation obtained byJ. C. Drummond, E. Singer, and R. J. Ma~walter,~~ and anotherobstacle is the failure of other investigators to isolate a-tocopherolin significant amounts from these oil concentrates.J. C. Drummond a,nd A. A. Hoover 76 have reinvestigated theunsaponidiable fraction of wheat germ oil and report that the resultsof attempts to separate a- and p-tocopherol as the allophanates weredisappointing. The p-allopha>nate was obtained, but in no singlecase after distillation was a-tocopherol allophanate isolated.Theiodine value of p-tocopherol suggests the presence of three ethylenelinkages, and of the two oxygen atoms, one is present in a non-phenolic reactive hydroxyl group and the other may be present inan ether linkage.77An exhaustive investigation of the unsaponifiable fractions ofrice and wheat germ oils has been carried out by A. R. Todd, F.Bergel, H. Waldmann, aEd T. S. Work.'* Three apparentlyhomogeneous alcohols, u-orysterol (m. p. 121-122"), p-orysterol(m. p. 113-114"), and y-orysterol (m. p. 119--120"), all havingthe approximate formula C,,H,,O, were isolated from rice germ oil,and wheat germ oil yielded p-amyrin, a-tritisterol (m. p. 113-114"),and a third alcohol (m. p. 174-175'). The authors suggest thatthese products, which have similar properties, may not impossiblybe mixtures of closely related compounds.All are devoid ofviitamin E activity. Compounds of the same type have beenisolated from wheat germ oil by P. Karrer and H. S a l ~ m o n , ~ ~ wh_oname their products cc- and p-tritisterols.The method of isolating tocopherols as the allophanates hasbeen improved by A. R. Todd, F. Bergel, and T. S. Work,SO whohave been able to isolate @-tocopherol allophanate in fair yieldfrom wheat germ oil. On hydrolysis this allophanate yieldsp-tocopherol, which shows full vitamin E activity in a dose of5 mg. and possibly less. The vitamin E activity of the wheatgerm oil concentrate used appears to be due almost entirely to thisalcohol. No significant amount of a-tocopherol allophanate could7 6 Biochem.J., 1935, 29, 2510.77 Cf. also E. Fernholz ( J . Arner. Chem. SOC., 1937, 59, 1154), who suggeststhat a-tocopherol is a monoether of duroquinol. F. Bergel, A. R. Todd, andT. S. Work (Chem. and Ind., 1937, 56, 1054) have also obtained duroquinolby the decomposition of active oils and in addition a quinol (m. p. 165') whichis possibly identical with #-cumoquinol. The latter authors suggest thatj3-tocopherol and " cumotocopherol" may be identical.76 Ibid., 1937, 31, 1852.7 8 Nature, 1937, 140, 361 ; Biochem. J., 1937, 31, 2247.7a Helv. Chim. Acta, 1937, 20, 424. 80 Biochem. J., 1937, 31, 3257412 BIOCHEMISTRY.be isolated, but appreciable amounts of other a,llophan' iL t es wereobtained; one of these is phytyl allophanate (m.p. 78").Further work on p-tocopherol and its isolation in larger amountswill most probably overcome the present difficulty of carrying outvitamin E assays without an accepted unit or a standard prepara-tion. This difficulty is pointed out by A. L. Bacharach, E. All-chorne, and €€. E. GlynnYs1 who discuss fully the reproductivebehaviour of female rats fed on a vitamin E-deficient diet fromweaning to maturity, and suggest that a period of vitamin E-deficiency may have an effect on the reproductive system of thematernal organism much more deep-seated than has hitherto beenbelieved. In this connection it is of interest to note that M. M. 0.Barrie 82 has found that deprivation of vitamin E leads to thyroidand anterior pituitary deficiency, and that definite pathologicalchanges in the latter can be demonstrated in vitamin E-deficientrats.Diet.The truly amazing success of investigations on vitamins duringrecent years may have tended to place in the background t,heproblem of general dietary requirements, and there was a dangerthat this more spectacular work on the chemistry of the vitaminswould completely overshadow observations on other, and probablyno less important, aspects of diet.This pitfall has, however, beenavoided, and the majority of experts on nutrition are able to takea broad view of the whole field.The present time appears opportune for a reconsideration of thedietetic requirements of man and for a general consideration of thestate of nutrition in various parts of the world.The task of makingthese surveys was undertaken by the Health Committee of theLeague of Nations, and the outcome is an excellent series ofReports 83 which may be said to contain the cream of our present-day knowledge on the subject. To the biochemist and physiologist,Volume I1 of this series will offer most interest, for it presents acompact and yet surprisingly comprehensive account of most of theessentials of nutrition. The decision of the Commission to reachagreement as to the calorie, protein, and other requirements of theaverage man will be approved by all who have had to offer "ex-81 Biochenz. J., 1937, 31, 2287.82 Nature, 1937, 139, 286; 140, 426; Lancet, 1937, 233, 251.83 League of Nations Publications. The Problem of Nutrition.Vol. I.Interim Report of the Mixed Committee on the Problem of Nutrition (Ser.L.O.N.P. 1936, 11, By 3). Vol. 11. Report on the Physiological Bases ofNutrition (1936, 11, B, 4). Vol. 111. Nutrition in Various Countries (1936,11, B, 5 ) . Vol. IV. Statistics of Food Production, Consumption and Prices(1936, 11, B, 6). Final Report (1937, IT, A, 10)WORMALL : ANIMAL. 413planations " for the widely differing accounts given in differenttext-books, and it is to be hoped that the details given in theseReports will find their way into all text-books which deal with diet.Amongst the special recommendations of the Commission are thepartial replacement of white flour by lightly milled cereals andespecially by potatoes. The last-named provide extra vitamin Cand contain more readily available calcium and phosphorus thando the cereals; they also yield more iron and B vitamins that domilled cereals.The suggestion that milk should form a conspicuouselement of the diet a t all ages should not meet with serious opposi-tion, nor will the recommendation that fresh vegetables and/orfruit should always be constituents of the normal mixed diet.Special reference is made to the high nutritive value of skimmedmilk, which contains the protein, the B and C vitamins and thecalcium and other mineral constituents of the original milk.Perusal of these reports shows that that much malnutrition un-doubtedly exists, even in the richer countries, and suggestions aremade as to the best methods of improving the general standard ofnutrition.Another report which is worthy of careful study deals with thenutritional, hygienic, and social aspects of the milk problem.8*The value of this most important foodstuff, as a source of certainof the vitamins and of protein of high biological value, is discussedin the light of modern views as to the minimum daily requirements.The diet of the cow itself has not been neglected, a.nd it is recom-mended that the animal ration should contain ample supplies ofvitamins A and D.Where necessary, vitaminised products, suchas irradiated yeast, should be supplied. After consideration of themode of collection of milk and the frequency of milk-borne diseasesin human beings, the conclusion is reached that no raw milk canbe regarded as completely safe for human consumption. Theauthors of this report suggest quite emphatically that '' all liquidmilk for human consumption should be adequately pasteurised orboiled ", and after considering all the avalilable evidence they findthat there is no real basis for the fear that pasteurisation is detri-mental to the food value of milk.The nutritive value of bread and the vexed question of white!oersus wholemeal bread have again received prominent attention,and it seems likely that the use of modern weapons will enable theprotagonists of the " wholemeal '' view to annihilate completelytheir opponents.Up to the present, the contestants have had to84 By H. C. Bendixen, U. J. Blink, J . C. Druiiimoiid, A.81. Leroy, and (2. S.JTilson, Quuvterly Bulletitz of the Health Orgunisat ion (League of Nations),1937, 6, 371414 BIOCHEMISTRY.be content with evidence which was largely indirect and oftenhypothetical, but in more ween& times it has been found possibleto define more precisely the vitamin B, requirenents of man andthe amount of this vitamin present in various types of bread. Theremoval of the germ from wheat leads to the loss of other substancesbesides B,, but it is believed that in these other instances the lossis more likely to be made good by other articles of diet. The realdeficiency of white bread as compared with wholemeal breadappears, therefore, to be concerned with the B vitamins, andparticularly B,.L. J. Harris85 finds that, whereas ordinary white bread maycontain as little as 0.12 internat.unit of vitamin B, per gram,wholemeal bread may contain as much as 0-9 unit per g., withbran bread occupying an intermediate position. These measure-ments were rendered possible by the use of the bradycardia method,for the ordinary growth tests break down when used for the assayof vitamin B, in bread. Harris concludes that the variety of“ germ-bread ” examined is not greatly superior in B, content towholemeal bread, and that the ordinary “brown bread” ascommonly sold is a reasonably good source of B,.A. Z. Baker, M. D. Wright, and J. C. Drummond 86 have reachedsimilar conclusions about the brown versus white bread problem asa result of vitamin B, determinations on various types of breadand a calculation of the B, content of present-day and past diets.A most interesting account is given of the history of milling andit is suggested that the most fundamental change, as far as thepresent problem is concerned, was the introduction of the rollermill into this country about 1870; the general adoption of thissystem led to the almost complete removal of the germ and bran.An analysis of modern diets indicates a daily vitamin B, intake offrom about 290 units at the lowest income level to 450-550 for highincome groups.From data collected from various sources it appearsthat, a’lthough 300 units of B, per day may protect man from beri-beri, the minimum daily requirement for the full maintenance ofhealth is probably about 500 units.The inadequacy of the moderndiet thus becomes apparent. The authors give the calculatedvitamin B, contents of the diet of the parish poor of 1782 (660-850units per day) and that of the Poor Law diet, City of London, 1838(1060 units per day), and they hare ample justification for statingthat the best-fed members of the population to-day consume lessvitamin B, than the parish poor of the 18th and early 19th centuries.85 Biochem. J . , 1937, 31, 799; P. C. Leong andL. J. Harris, ibid., p. 812;L. J. Harrisand P. C. Leong, J. SOC. Chena. Ind.., 1937,86, 1951..8 6 J . SOC. Chem. Ind., 1937, 56, 1 9 1 ~ WOR,MALL : ANIMAL. 415k change froin white to wholemeal bread may add to the averagediet as much as 200 units of vitamin B, per day, and cndoubtedlya strong case has been made out for a general condemnation of thewhite loaf.The last word on this question has not been said,however, and the opposing camp will probably quote the observa-tions of A. M. Copping and M. H. who conclude that theB, content of white bread is sufficiently high for this food to providea significant part of the requirements for this vitamin, bearing inmind the large amounts of bread often consumed. As against thisview must be recalled that white bread as the sole diet hasfrequently been the cause of beri-beri.Some interesting observations on the effect of overfeeding on theprotein metabolism of man are recorded by D. P. Cuthbertson,A. McCutcheon, and H. N. M u n r ~ . ~ ~ The addition of raw orboiled milk (or a mixture of beef, lactose, and butter equivalent tomilk in protein, carbohydrate, and fat content) to a diet which wasadequate for nitrogen equilibrium and for the maintenance of bodyweight, caused an increase in body weight and marked retention ofnitrogen and sulphur.The degree of retention appears to be relatedto the total increment in the energy value of the diet. In a similarmanner, the addition of glucose, or to a lesser extent fat, to anadequate diet caused nitrogen and sulphur retention.8sThe significance of the mineral constituents of the diet is in mostinstances well recognised, mainly as a result of studies on smallanimals. In this field of investigation there are not many observ-ations on man, and for this reason the experiments of R.A. McCanceand his colleaguess0 are worthy of special attention. In order toproduce a sodium chloride deficiency in normal man, McCance andcertain other volunteers lived for about 11 days on a diet which wasfree, as far as possible, from this salt. Profuse sweating was alsoinduced to increase the salt loss of the body. The symptomsobserved are fully described and it is pointed out how closely thesesymptoms resemble some of those of Addison’s disease. This salt-deficiency leads to a disordered nitrogen balance,g0 a slight inter-ference with carbohydrate rnetaboli~rn,~~ and changes in the responseof the kidney to certain tests.92 Investigations of this type areobviously most difficult to carry out and cause much inconvenienceand discomfort to the subjects concerned, but they are of inestimable8 7 Biochem,.J., 1937, 31, 1879.89 D. P. Cuthbertson and H. N. Munro, ibid., p. 691.88 Jbid., p. 681.R. A. McCmce, Proc. Roy. SOC., 1936, B, 119, 246; Lancet, 1936, i, 643,704, 765, 823.91 Idem, Biochem. J., 1937, 31, 1276.92 R. A. McCaiice and E. M. Widdowson, Proc. Roy. Soc., 1936, B, 120,228; J . Physiol., 1937, 91, 222416 RI0C)HEMlSTRY.value for the study of many diseases where salt deficiency is aprominent feature. To quote another example, the investigationsof the same authors on the absorption and excretion of irong3 havefurnished valuable information about the availability of the iron ofvarious foodstuffs and about the storage of this element in the body.Prom the results obtained it appears that the animal body has littleor no power to excrete iron and any excess which is absorbedremains in the body.Carbohydrate Oxidation.In recent times two very interesting theories have been advanced,one by Szent-Gyorgyi and the other by H.A. Krebs, to explain howsimple carbohydrates are oxidised in animal tissues. These twotheories appear to have a certain amount in common, for both areconcerned with the action of dicarboxylic acids with four carbonatoms, but fundamentally they are very different.A. Szent-Gyorgyi and his colleagues in a series of investigations 94have shown that succinic acid and related C4-dicarboxylic acidsplay it dominant rble in certain tissue oxidations. These acids forman essential link in the respiratory chain between the oxidisablefoodstuff (probably a triose) and the oxidising system cytochromeplus Warburg's atmungsferinent .Oxidation (dehydrogenation) ispictured as a, transference of hydrogen froin the foodstuff to oxalo-acetic acid, which is thereby converted into nialic acid; malic acidpasses on its hydrogen to fumaric acid, which becomes succinicacid. The succino- and nialico-dehydrogenases catalysing thesereactions should be regarded as '' hydrogen-transportases "35 Thesuccinic acid is oxidised back to fumaric acid by cytochrome, theoxidation of which is catalysed by the Warburg enzyme. Thewhole process is summarised by Szent-Gyorgyi in the followingmanner (for convenience the (&-acids are represented as free acidsand not salts) :p 2 H TO& (p2HFoodstuff 2H THz -.-+ QHz 2H SH QHz I(Triose) -4- 70 - QH*OH --+ TH C-- YH2 IOxaloacctate. Malate.Fumarate. Suecinate. IOxygen - Atmungsferment -- Cytochrome +-J93 R. A. McCance and E. M. Widdowson, Lancet, 1937, ii, 680; Biochewz. J . ,2937, 31, 2029.94 A. Szent-Gyorgyi and his colleagues, 2. physiol. Chem., 1935, 236, 1 ;1936, 244, 105; 1937, 245, 113; 247, 1, 248, 2 5 2 ; 249, 57, 61, 63, 183. 189,205, 209, 211, 217.C02H C02H COZH C02H 1 2 ~I9 5 A. Szent-Gyfirgyi, ihid., 1937, 249, 211WORMALL : ANIMAL. 41 7According to this theory the hydrogen transference is carried outby a pair of reversible reactions (oxaloacetate jt malate ; andfumarate f succinate), and since fumarase can effect the changemalate fumarate, these four compounds can be regarded as" different forms of the same substance ".Support for this theoryis given in the many publications of Szent-Gyorgyi and his col-l e a g u e ~ , ~ ~ and by the observations of other investigators who haveworked in his laboratory. F. J. Stare, for example, has shown thatliver and kidney tissues can oxidise fumarate to oxaloacetate, andthat the reverse change, the reduction of oxaloacetate to malateplus fumarate, is almost q~antitative.~6As a result of these investigations, A. KorAnyi and A. Szent-Gyorgyi were led to consider the possibility that dia,betic acidosismay be due to a destruction of the C4-dicarboxylic acid catalysissystem. To test this hypothesis, succinic acid was administered tofive diabetics, to restore the C4-acid system to normal, and satis-factory results were reported.97 Thus 10 g.of this acid per 0sper day, with a reduction later to 1 g. per day, caused the " acetonebody " excretion to fall to zero or a very small amount. The hyper-glycaemia and glycosuria remained, but with succinic acid treatmentless insulin was required to control the diabetes. Unfortunately,other authors have failed to confirm these observations. R. D.Lawrence, R. A. McCance, and N. Archer 96 treated two diabeticswith succinic acid and reported the complete failure of this treat-ment. D. M. Dunlop and W. M. Arnott 99 in a similar trial withthree patients found that succinic acid does not prevent the onsetof diabetic coma, nor does it diminish a chronic diabetic ketonuria.H.A. Krebsl has presented a somewhat different scheme toindicate the r61e of C4-dicarboxylic acids in the tissue oxidation ofcmbohydrate. Like A. Szent-Gyorgyi, Krebs considers that oxalo-acetic acid is the prime agent which is responsible for triose oxidation,but he suggests that this acid condenses with an unknown substance(a carbohydrate derivative and most probably pyruvic acid) toproduce citric acid. Citric acid is then transformed, througha-ketoghtaric, succinic, and furnaric acids, to oxaloacetic acid, thuscompleting the " citric acid cycle ". Viewed as a whole, theprocess can be regarded as the " attachment " of pyruvic acid (orits equivalent) to a C4-dicarboxylic acid, and the removal of carbondioxide and water in stages to produce once more the C4-acid. Thefollowing scheme, which is a slight modification of that given byKrebs, indicates the main features of the cycle.9 6 Biochem.J., 1936, 30, 2257.98 Brit. Med. J., 1937, ii, 214.1 Ibid., p. 736; of. also ref. 2.9 7 Deutsche med. Woch., 1937, 63, 1029.99 Lancet, 1937, 233, 738.REP .-VOL . XXXIV . 418 BIOUHEMISTRY.J.Oxaloacetic acid + carbohydrateL I VCitric acid + CO,derivative ( ? pyruvic acid)cc-Ketoglutaric acid + CO, + H,O lo Succinic acid + CO,t.1OFumaric acid + H,ONet change : CH,-CO*CO,H + 5 0 --+ 3c0, + 2H,OIt is difficult in LC short review to discuss the whole of the evidenceon which this scheme is founded, but a few of the more salientfeatures of this work might be mentioned.M:. A. Krebs andW. A. Johnson2 found that citric acid catalyses the oxidation ofcarbohydrate in muscle just as does succinic acid, and that, underanaerobic conditions, muscle can readily synthesise citric acid fromoxaloacetic acid. The same authors have also confirmed andsupplemented the observation of C. Martius and F. Knoop3 thatoxidation of citric acid by certain tissues yields a-ketoglutaric acid.This last acid is known to yield succinic acid and carbon dioxide inthe body, and the change from oxaloacetic acid (or citric acid) tosuccinic acid can be demonstrated in respiring muscle tissue whenmalonate is added to inhibit oxidation of the succinic a ~ i d . ~ * ~ Theinterconversion of succinic, fumaric and oxaloacetic acids has beenwell e~tablished.~~ This citric acid cycle appears to occur generallyin animal tissues, but not in yeast or B.coZi, and quantitativemeasurements suggest that it is the chief pathway of oxidation ofcarbohydrate in muscle (H. A. Krebs and W. A. Johnson).2The formation of ketonic substances as intermediates in carbo-hydrate metabolism has also been studied by H. A. Krebs andW. A. J~hnson,~ who suggest that acetic acid and pyruvic acidcombine to give acetopyruvic acid. Evidence is produced that thelast-named is metabolised by animal tissues (liver, muscle, etc.)to yield acetoacetic acid (aerobically) or p-hydroxybutyric acidEnzymologia, 1937, 4, 148.2. physiol. Chern., 1937, 248, 1.Biochem.J., 1937, 31, 645, 772WORMALL ANIMAL. 419plua carbon dioxide (anaerobically). The following scheme indicatesthe reactions which are most probably concerned :CH,*COeCO,H --% CH,-CO,H $- GO,CH3*CO*C0,H + CH3*C02H __P CH3*CO*CH,*CO*C0,H + H20Acetopyruvic acid.CH3*CO*CH2*C02H + CO,CH,-CO*CH,*CO*CO,H f$ Acetoacetic acid.-* CH,*CH(OH)*CH,*CO,H + CO,fl-Hydroxybutyric acid.The rate of these reactions is small compared with the citric acidcycle, but this alternative pathway of carbohydrate breakdown maybe of value in explaining certain features of diabetic acidosis. Failureof the citric acid cycle would lead to the conversion of more pyruvicacid into ‘‘ acetone bodies ”; the last-named may therefore bederived from carbohydrate as well as from fatty acids (see alsoA.Szent-Gyorgyi 94*97).These theories of carbohydrate oxidation have been describedhere at some length, but this course has been adopted because itseems likely that these views will continue to attract much attention.Criticism has been, and will be, made that the demonstration ofthe presence in tissue slices and minced tissue of systems which arecapable of effecting certain changes does not necessarily prove thatthese changes represent the main processes of metabolism in theintact animal. There is evidence, however, of a tendency to makestudies of this type more quantitative in nature, and where this isdone, it is possible to assess more accurately the significance of thevarious reactions. The investigations which have yielded evidenceagainst the theories of A.Szent-Gyorgyi and H. A. Krebs cannotbe dealt with in a short review, but the observations of J. M. Innesmight be quoted as being pertinent and typical. This author findsthat fumaric acid added to minced pigeon breast musale increasesthe oxygen uptake by an amount which is not greater than can beaccounted for by oxidation of some of the fumaric acid whichdisappears. It is suggested, therefore, that fumaric acid is utilisedas a substrate for respiration and not as a catalyst for transferenceof oxygen to other substrates in the muscle.Amongst other investigations which should have a very prominentplace in any review on oxidation are those of J. H. Quastel and hiscolleagues, who have studied the oxidation processes taking placein brain and other tissues.The inhibitory action of hydroxyrnalateon lactate, and to a lesser extent glucose, oxidation by brain6 Biochem. J., 1936, 80, 2040420 BIOCHEMlSTRY .suggests that this tissue can oxidise glucose by a mechanism whichdoes not involve lactate as an intermediary.6 Important resultshave also been obtained by studying the effect of certain narcotics(chloretone, luminal, and evipan) on brain oxidations, and it hasbeen observed that the narcotic concentrations which producenarcosis in vivo are of the same order of magnitude as those whichinhibit the in vitro respiration of cerebral cortex.’ Similar studieswith ether have shown that this substance is like the other narcoticsin some respects, but unlike in others.sThe investigations of R.A. Peters and his colleagues on therelationship between vitamin Is, and oxidations in brain have beendiscussed in the section on vitamins. For an account o€ the changeswhich are concerned with muscle contraction the reader is referredto a review by D. M. Needhamtg and to a recent paper on dis-mutations and oxidoreductions by D. E. Green, D. M. Needham,and J. G. Dewan.lo The intermediary carbohydrate metabolismin embryonic life has been the subject of extensive investigation byJ. Needham and his colleagues,11 who suggest that their results maybe interpreted upon the hypothesis that in the chick embryo thereare two separate routes of carbohydrate breakdown; (1) a veryactive non-phosphorylating glucolysis mechanism and (2) a phos-phorylating mechanism closely similar to that in muscle.Themachinery for the second system does not appear to have been laiddown fully in early embryonic development.Chemotherapy.The Prontosil Group of Drugs.-Reference was made in theseReports last year to the discovery that prontosil and prontosil Sare efficacious in the treatment of certain streptococcal infections.During the past year definite advances have been made in ourknowledge of the value and mode of action of these drugs and relatedcompounds. Most of them are given by the mouth, and, whereeffective, they usually have a marked and almost dramatic action.Unfortunately the use of these sulphonamide derivatives is riotdevoid of danger.In addition to the above-mentioned azo-compounds (prontosiland the more soluble prontosil S), sulphanilamide [p-aniinobenzene-6 M.Jowett and J. H. Quastel, Biochem. J . , 1937, 31, 275.7 Idem, ibid., p. 565. Idem, ibid., p. 1101.D “ Chemical cycles in muscle contraction.”10 Biochern. J . , 1937, 31, 2327.11 J. Needham and W. W. Nowidski, ibid., p. 1165; J. Needham, W. W.Nowiliski, K. C. Dixon, and R. P. Cook, ibid., p. 1185; J. Needham andH. Lehmann, ibid., pp. 1210, 1913.A chapter in “ Perspectivesin Biochemistry.” Cambridge Univ. Press, 1937WORMALL : ANIMAL. 42 1sulphonamide (I) or sdphonamide-PJ and many of its derivativeshave been tested. Benzylsulphanilamide [proseptasine (11)] andsodium 4 - sulphonamidophen y l- y -phenylprop ylamiI1e - ay -disulphonate[soluseptasine (IZI)] are amongst those which are available in thiscountry.(I.) N H 2 0 0 , * I V H ,(11.1 ~ H , - N H < > O , ~ N H ,(111 * ) 0p;E2*p=; C ) S 0 2 * N B ,A.T. Fuller l2 has shown that prontosil is broken down in theanimal body to yield sulphanilamide (I), an observation whichsupports the suggestion13 that the latter is the active agent inprontosil therapy. This would account for the high in vivo, a8compared with a negligible in vitro, bactericidal activity of prontosil,and for the fact that, following the administration of prontosil (orsulphanilamide), the blood of man and other animals is bactericidaltowards haemolytic streptococci.14 Various investigators haveendeavoured to find a derivative of sulphanilamide which is morepotent than this compound in the treatment of streptococcal infec-tions, but in many instances with little success.1s E.Fourneau,J. Trhfouel, F. Nitti, D. Bovet, and (Mme.) J. Trefouel lG find,however, that 4 : 4’-dinitrodiphenyl disulphide is 4-8 times andthe corresponding sulphone 10 times as active in protecting miceagainst streptococcal infections as is sulphanilamide. The samegroup of authors find a similar high activity shown by 4 :4’-di-acetamidodiphenylsulphone and 4 : 4’-diaminodiphenylsulphone.17G. A. H. Buttle, D. Stephenson, S. Smith, T. Dewing, andG. A. H. Poster 18 find that, compared with sulphanilamide, 4 : 4’-di-aminodiphenylsulphone is much more effective, and 4 : 4‘-dinitro-diphenylsulphone as effective and less toxic, when used to curestreptococcal infections in mice.Other interesting discoveries inl3 Lancet, 1937, 232, 194.13 J. and Mme. J. Trr5fouG1, F. Nitti, and 2). Bovet, Conapt. rend. Xoc. Biol.,1935, 120, 756.14 L. Colebrook, G. A. H. But’tle, and R. A. &. O’Meara, Lancet, 1936, 231,1323.16 J. and Mme. J. Trkfouel, I+’. Nitti, and D. Bovet,, Ann. I n s t . Pasteur,1937, 58, 30; W. H. Gray, G. A. H. Buttle, and D. Stephenson, Biocheni,. J . ,1937, 31, 724.16 Conzpt. rend., 1937, 204, 1763.17 E. Fourneau, (Mme.) J. Trkfoulil, J. Tri.foue1, 17. Nitti, and D. Bovet,Compt. rend., 1937, 205, 299.l8 Lancet, 1937, 232, 1331422 BIOCHEMISTRY.this field relate to the action of the “ diseptals ” A, By and C, com-pounds which have been found to be superior to some of the‘‘ prontosil ” preparations in the treatment of staphylococcal,gonococcaI, and certain other infe~ti0ns.l~ It is worthy of note thatsubstitution in the free sulphonamide group does not necessarilydestroy the bactericidal action.Diseptal C H2N<>SO2*NH<>O2*NH2E. K.Marshall, K. Emerson, and W. C. Cutting 2O have describeda method for the determination of sulphanilamide in blood andurine, based on the diazotisation of the amine and coupling of thediazo-compound with dimethyl-a-naphthylamine in acid solutionto form a purplish-red azo-dye. With the aid of this method theseauthors have found that the absorption of sulphanilamide from thealimentary tract is very rapid and is nearly complete in 4 hours;thus no advantage is gained by injecting the substance.It isexcreted in the urine mainly in the unchanged form by dogs, andboth free and conjugated by man and rabbits.21 The conjugatedform is mainly, if not entirely, p-acetamidobenzenesulphonamide.22This group of drugs has been used in the treatment of variousbacterial infections, but it is probably too early to give a dogmaticopinion as to the results of these tests. Successful results areusually obtained when the infection is due to the @-hamolyticstreptococci 23 (e.g., in puerperal sepsis, erysipelas, certain types oftonsilitis, streptococcal meningitis, etc.), and often with menin-gococcal infections Z4 and B. coli infections of the urinary tract.251 0 Cf.review by H. Hoerlein, Practitioner, 1937,139, 635.20 J . Amer. Med. ASSOC., 1937,108,953, and a, modification by E. K. Marshall,Proc. SOC. Exp. Biol. Med., 1937, 36, 422; J. Biol. Chem., 1937, 122, 263;cf. also A. T. Fuller, ref. (12).21 Cf. also A. T. Fuller, ref. (13), who found both free and conjugated formsin the urine of men and mice.82 E. K. Marshall, W. C. Cutting, andK. Emerson, Science, 1937, 85, 202.2s For the literature, see I;. Colebrook and M. Kenny, Lancet, 1936, 230,1279; 231, 1319; L. Colebrook and A. W. Purdie, ibid., 1937, 233, 1237,1292; P. H. Long and E. A. Bliss, Arch. Surg., 1937, 34, 351 ; J . Amer. Me&ASSOC., 1937, 108, 32.24 In mice:-G. A. H. Buttle, W. H. Gray, and D. Stephenson, Lancet,1936,230,1286 ; H . Proom, ibid., 1937,232,16.In man :-F. F. Schwentker,S. Gelman, and P. H. Long, J . Amer. Med. Assoc., 1937,108, 1407.26 M. Kenny, F. 13. Johnson, and T. von Haebler, Lancet, 1937, 233, 119WORMALL : ANIMAL. 423Satisfactory results are claimed by most investigators when thesedrugs are used for gonococcal infections, but others report negativeresults.Toxic effects following the use of sulphanilamide and relatedcompounds include irritation of the kidney, fever, dizziness, mildnausea, acidosis, methzmoglobinzemia, sulphmnoglobinaemia,haemolytic anzemia and agranulocytosis, of which the last two appearto be the most serious. The appearance of sulphaemoglobin in theblood of patients receiving drugs of this group has been observedby many investigators26 and is a much commoner consequence ofthis treatment than has hitherto been recognized (G.Discombe 27).H. E. Archer and G. Discombe28 conclude that sulphanilamideand related compounds catalyse in the body the reaction betweenhzmoglobin and hydrogen sulphide (which is absorbed from theintestinal tract). These authors suggest that no aperient other thanliquid paraffin should be given during treatment with these drugs,and that a low-residue diet should be given to minimise bacterialdecomposition in the colon.L. Colebrook and A. W. Purdie29 have recently reported thesatisfactory results obtained by treatment of 106 cases of puerperalfever with sulphanilamide. Some toxic effects were observed.Cyanosis, which was associated in nearly all instances with methz-moglobin or sulphzemoglobin or both in the blood, was shown byover 50% of the cases.It was concluded, however, that althoughan undesirable feature, the cyanosis had no adverse effect on theprocess of recovery. No development of agranulocytosis was.observed in these cases, but this serious sequel to sulphanilamide orprontosil treatment has been recorded by several authors.30In spite of these dangers, there appears to be no doubt thatsulphanilamide and related compounds have an extremely hightherapeutic value. Because of the possibility of toxic effects, how-ever, treatment with these drugs should be carefully controlled, andmost authorities in this field are agreed that any tendency towardsthe indiscriminate use of these drugs for every type of bacterialinfection is to be deprecated.Trypanosomiasis.-In this field of chemotherapy there have beenvery interesting developments during the past year.From the26 L. Colebrook and M. Kenny, Lancet, 1936,230, 1279; G. Discombe, ref.(27); M. A. Foulis and J. B. Barr, Brit. Med. J., 1937, i, 4-45; J. R. J. Patonand J. C. Eaton, Lancet, 1937, 232, 1159.2' Lancet, 1937, 232, 626.28 Ibid., 1937, 233, 432.29 Ibid., pp. 1237, 1292.30 J. G. G. Borst, ibid., 1937, 232, 1519; C. J. Young, Brit. Med. J., 1937,ii, 105424 BIOCHEMISTRY.scientific view point and perhaps even more important the treat-ment of trypanosomiasis and related diseases, the most promisingis that concerned with the action of guanidines and related com-pounds on trypanosomes .Over a period of many years it has been shown by many authorsthat trypanosomes metabolise large amounts of simple carbo-hydrate3I (indeed it has even been suggested that the death ofsmall animals infected with trypanosomes is due in.part to a hypo-glycaemia accompanied by the acidosis associated with the accumu-lation of lactic acid). N. and H. von Jams6 32 suggested thattrypanosomes suffering from " sugar-hunger " are more readilyphagocyted by the reticulo-endothelial cells, and that the opsoniceffect produced by Bayer 205 may depend on the toxic inhibitionby this drug of the sugar metabolism of the trypanosomes. Asa sequel to these observations the same authors studied the trypano-cidal action of synthalin (decamethylenediguanidine)? a substancewhich is known to produce hypoglycEemia in animals,33 and claimedthat this substance had a high curative effect when injected intoanimals infected with certain strains of T.bruceL3* K. Schern andR. Artagaveytia-Allende in a similar investigation 35 found that smallamounts of synthalin will cure T. equinum and T. hispanicurn butnot T. crzcxi infections. The in witro trypanocidal action ofsynthalin has been investigated fully by E. M. Lourie and W. Yorke,36who found that a concentration as low as 1 in 256,000,000 will killpractically all the trypanosomes in a suspension kept at 37" for24 hours. These authors concluded that the therapeutic action ofsynthalin is due to a direct lethal action on the trypanosomes.Very recently3' H.King, E. M. Lourie, and W. Yorke havedescribed the results of investigations which appear to open up animmense field in the search for trypanocidal agents. The in vitroand in vivo trypanocidal action of a series of hornologues of synthalinhave been tested, and a considerable therapeutic effect was observedwith those compounds containing 10 to 14 methylene groups. Otherguanidines, isothioureas, amidines, and amines, with alkyl andalkylene chains, were also prepared and tested. High trypanocidalactivity was shown by certain alkylenediamidines, compounds withtwo guanyl groups [NH:C(NH,)-] attached to the ends of a methylenechain. The most active member of two series is n-undecane-31 K. Schern, Zentr. Bakt. Orig., 1925, 96, 356, 360, 362, 440, 444, 451;Deutsche med.Woch., 1927, 53, 106; W. Yorke, A. R. D. Adams, andF. Murgatroyd, Ann. Trop. Med. Parasitol., 1927, 23, 501.32 Z . Irnmunitat., 1935, 84, 471.34 2. Immunitat., 1935, 86, 1.36 Ann. !Prop. Med. Parasitol., 1937, 31, 435.a7 Lancet, 1937, 233, 1360.33 Ann. Reports, 1927, 24, 264.36 B i d . , 1936, 89, 21, 484WORMALL : ANIMAL. 425diamidine, which is a t least as active in vitro as is synthalin andmuch less toxic. In vivo tests show quite quite definitely thatundecanediamidine can permanently cure laboratory animalsinfected with trypanosomes, and that it has a therapeutic valuemuch superior to that of synthalin. Further points of interestmentioned by these authors are that the trypanosomes do notappear to acquire very rapidly, if a t all, any resistance to the drug,and secondly that trypanosomes which have previously acquired aresistance to Bayer 205 or to arsenicals, are very sensitive toundecanediamidine.The special significance of the latter observ-ation is obvious when it is remembered that the large-scale use ofarsenicals for the treatment of sleeping sickness is accompanied bythe risk of the production of arsenic-resistant strains of trypano-somes. A further development of this work, which hasdemonstrated the high trypanocidal action of compounds with aconstitution entirely different from that of other known trypanocidalagents, will be awaited with considerable interest.Amongst other investigations on trypanosomiasis might bementioned those dealing with the action of Bayer 205 (germanin).This drug has a most powerful in vivo destructive action on trypano-somes, but in vitro it has practically no trypanocidal effect.Whenthe organisms are kept in a serum-Ringer-glucose solution a t 37”,however, a concentration of Bayer 205 of 62 mg. per 100 ml. (i.e.,62 ( ( mg.% ”) will kill all the trypanosomes present.38 N. and H.von Jancs6 39 report that as little as 1.7 mg.% is sufficient to kill theorganisms within 24 hours, but 3’. Hawking 40 finds that 125 mg.% isneeded for this purpose, although 31 mg.% will suffice to kill most ofthe trypanosomes. Much evidence is now forthcoming to show thatthe effect of this drug is indirect, and that it has an opsonin-likeaction on the trypanosomes, thus rendering them more susceptibleto the action of the phag~cytes.~~ Support for this view has beenobtained by F.Hawking,40 who finds that exposure to 10 mg.% ofBayer 205, a concentration considerably below that required tokill them, renders the trypanosomes incapable of infecting mice.A method for the determination of Bayer 205 in blood-plasma hasbeen devised by W. G. Dangerfield, W. E. Gaunt, and A. Wormall,and the presence of small but significant amounts of this drug inthe plasma of small animals three or four months after a single98 W. Yorke, F. Murgatroyd, and F. Hawking, Ann. Trop. Med. Parasitol,,1931, 25, 313.39 Zentr. Bakt. Par., 1934, 132, 257; cited from Trop. Dis. Bull., 1935, 32,22.49 In the press (personal communication to the Reporter).4 1 I,.Reiner and J. Koveskuty, Deutsche med. Woch., 1927, 53, 1988;N. and H. von Jancsb, Ann. Trop. Med. Parasitol., 1934, 28, 419426 BIOCHEMX3TRY.injection of a " normal " dose of the drug has been demonstrated.&Over this long period the amount of Bayer 205 in the plasma ismaintained at a level which may be sufficient to exert the opsonicaction noted by the above-mentioned authors.Recent developments in connection with the use of variousarsenicals for the treatment of trypanosomiasis and syphilis andthe problem of arsenic resistance were reported last year.43 Men-tion might be made, however, of a new method of approach devisedby F. Hawking, T. J. Hennelly, and J. H. Quastel44 for the studyof the efficiency of drugs used for syphilis and trypanosomiasis ofthe central nervous system.This method, which has furnishedresults of considerable interest, consists of a determination of thein vitro trypanocidal power of the cerebrospinal fluid, withdrawnafter administration of the arsenical, and comparison with the arseniccontent of the fluid.A. WORMALL.2 . PLANT BIOCHEMISTRY.Plant Viruses.Isolation and Nature of the Tobacco Mosaic Virus.--Virus diseaseswhich have presented such an enormous problem in medical andveterinary research, find a counterpart in the plant world. Foryears mosaic diseases, spotted wilt and bunchy top of tomatoes,curly top of beet, etc., have been traced to the activity of viruses,the units of which are frequently too small to be separated onbacterial filters.Although the infectivity of juices of diseasedplants suggests the virus to be an extraordinarily active livingorganism, the extreme rapidity with which its physiological effectsare translocated through plant tissue, and the speed and extent towhich the active material multiplies are perhaps more in keepingwith the properties of a biocatalyst.Controversial views as to the fundamental character of the virushave been modified very considerably by the work of W. M. Stanleyand colleagues, who have isolated from the juice of diseased tobaccoplants a crystalline substance exhibiting a high order of infectivityapproximating to 500 times that of the juice itse1f.l The methodof isolation of the active substance (fractional precipitation withammonium and magnesium sulphates), its nitrogen content ( 166y0),and its positive reaction to common protein reagents (trichloroacetic,42 Chem.and Ind., 1935, 55, 1029; Biochern. J., in the press.43 Ann. Reports, 1936, 33, 403.44 J . Pharm. Exp. Ther., 1937, 59, 167.1 Science, 1935, 81, 644; Phytopath., 1936, 26, 305; J. Biol. Chenz., 1936,81, 673POLLARD : PLANT. 427phosphotungstic, tannic acids) establish the protein character ofthe substance and confirm the earlier observations of, among others,E. Barton-Wright and A. At. McBain and also C. G. Vinson andA. W. PetreY3 who had effected a partial separation of the activematter, shown it to be nitrogenous, and speculated as to its probablechemical nature.Earlier preparations had contained phosphorusand sulphur, which, however, were separable by dialysis.The purified protein forms minute crystals (0.024-03 mm. indiameter) which are optically active ( [ a ] - 0.43') and doublyrefractive, and give characteristic X-ray patterns (R. W. G. Wyckoffand R. B. Corey4) which are identical with those observed inpreparations obtained by direct ultra-centrifuging of the juice ofdiseased plant^.^ H. P. Beale makes the interesting observationthat certain intracellular inclusions occurring in mosaic-infectedtobacco can be observed under the microscope to yield, ontreatment with dilute hydrochloric acid, crystals identical withthose obtained by Stanley. Ultracentrifugal analysis of theprotein by R.W. G. Wyckoff, J. Biscoe, and W. M. Stanley 7indicates a molecular weight of approximately 17 millions andcodrms the value obtained by I. B. Eriksson-Quensel and T.Svedberg.8 The latter workers also record the isoelectric point ofthe protein as pH 3-49.The juice of healthy plants contains proteins of molecular weightnot exceeding 30,000, and no evidence of even small amounts ofhigh-molecular proteins has been found. In diseased plants themosaic infection appears to stimulate abnormally high proteinproduction, and extracts may contain double the normal contentof total protein, of which the virus protein may constitute up toThe physical nature of the virus protein particles both withinthe plant and in vitro appears to be somewhat complex.W. N.Takahashi and T. E. Rawlins show that suspensions of the crystalsin ammonium sulphate solution contain not only visible crystalsexhibiting a stream double refraction, but also a colloidal solutionof the protein. It is suggested that the solution contains sub-microscopic rod-shaped particles. Change in the reaction of the80 yo.Nature, 1933, 132, 1003.Bot. Gaz., 1929, 87, 14; Contr. Boyce Thompson Inst., 1931, 3, 131;Science, 1934, '70, 548.4 J . Biol. Chem., 1936, 116, 51.5 R. W. G. Wyckoff and R. B. Corey, Science, 1936, 84, 513.6 Contr. Boyce Thompson Inst., 1936, 8, 333.7 J . Biol. Chem., 1937, 117, 57; also WyckoE, Compt. rend. Soc. Biol.,8 J . Amer. Chern. SOC., 1936, 58, 1863.1937,125, 5.Science, 1937, 85, 103428 BIOCHEMISTRY.suspension results in an altered proportionality between theamounts of visible crystal and colloidal solution.F. C. Bawden,N. W. Pirie, J. D. Rernal, and I. Fankuchen,lo working with anaqueous solution or suspension of the highly purified protein, havefound that this separates into two layers, the upper exhibitinganisotropy of flow, and the lower containing liquid crystals whichon drying yield a gel. The crystalline liquid and the gel giveidentical X-ray patterns. The gel stage probably consists ofhexagonally-packed particles, and the crystals of parallel, charged,rod-like molecules. The molecular weight of the protein calculatedfrom the size of the particles approximates to 17 millions (cf.Wyckoff et a?.'). In a further examination of the X-ray pattern ofthe crystals J.D. Bernal and I. Panbuchen l1 suggest that,although the long protein molecules are packed hexagonally andwith regularity a t right angles to their length, no regularity in thedirection of the packing exists. The molecules themselves aremade up of sub-molecules of definite size. Intermolecularreflections can be observed, and the authors put forward thepossibility of distinguishing and classifying viruses by means ofX-ray observations. The juice from mosaic-infected plants afterclarification by the centrifuge and storing a t a little above 0" isfound l2 to contain the virus in the form of flexible fibres, probablyconsisting of chains of protein particles weakly linked together.These fibres disintegrate or collapse when warmed to thetemperature a t which the virus loses its infectivity (70-75').The homogeneity of the crystalline virus protein has been amplydemonstrated by the constancy of the physicochemical propertiesof samples from various sources. The X-ray pattern of the crystalsis unchanged after repeated cry~tal1isation.l~ Ultracentrifugalanalysis shows the same sedimentation constant for the high-molecular protein in affected plant juice, for the crystallinecentrifugate, and for the isolated crystalline protein after extensivechemical purification. Moreover, repeated fractional crystallisationof the protein has failed to modify its infectivity.14 According toStanley,15 g.of the protein in 1 C.C. of water is almost invariablysufficient to infect the tobacco plant and in some cases 10-14 g.(i.e., approx.300 molecules) gives a positive response.Inactivation. Innumerable experiments show that whateverthe nature of the tobacco mosaic virus preparation, the presencelo Nature, 1936, 138, 1051.l2 R. J. Best, ibid., p. 628.Is R. W. G. Wyckoff and R. B. Corey, J . Bid. Chem., 1936, 116, 51.l4 H. S. Loring and W. M. Stanley, ihid., 1937, 117, 733.l1 Ibid., 1937, 139, 923.Science, 1935, 81, 644POLLARD : PLANT. 429of the high-molecular protein is always synonymous with infectiveproperties, and that treatments causing denaturation or decom-position of the protein inevitably destroy the power of inducingthe disease and of stimulating rapid formation of the characteristicprotein in tobacco-plant tissues.Thus Stanley l6 observes thatheating at 75" or transference to media of p H < 1 or > 11 denaturesthe protein and destroys virus activity. In a more detailedinvestigation R. J. Best 17 demonstrates that irreversible inactivationof the virus is initiated at pH 7.8 and is substantially complete atpH 10.2. The p=-activity curve is of the same character as theneutralisation curve of a weak acid and leads to the suggestionthat inactivation results from the neutralisation of acidic groups inthe prosthetic part of the protein molecule. Changes in the,properties of the virus are also associated with similar though notidentical ranges of pH by H. H. Thornberry.l* At pH 8.5 the viruspasses freely through a Berkefeld " W '' filter candle, but at pH 1.5it is held back and is adsorbed by the filter, from which it may beeluted by phosphate buffer solutions a t p H 8.5, a considerableconcentration of virus preparations thus being possible.Optimuminfectivity is apparent at pH 7.0-8.5. At p H 10.6 infectivity iscompletely lost in 4 hours, and at p H 11.2 inactivation is completein 5 minutes. This general range of significant pH values is inconformity with Stanley's observations.The activity of the protein appears to be eliminated fairlyrapidly by digestion with trypsin l9 and slowly by pepsin,20although it is not certain that the action in the second case is adirect proteolysis.21 Oxidising agents (hydrogen peroxide, nitrousacid) and ultra-violet light destroy the infectivity of the protein,which, however, may still exhibit certain of the initial chemicaland serological properties.22 Protein precipitants inhibit theactivity of the virus.In the case of tannic acid the effect isreversible, removal of the tannic acid restoring activity. Treatmentof plants with tannic acid before, but not after, inoculation withthe virus suppresses the infection to a degree which is proportionalto the dosage of tannic acid.23 Virus preparations are also renderednon-infective by reduced ascorbic acid, oxygen being necessary forthis action, which is catalysed by copper salts. M. Lojkin2416 Phytopath., 1935, %, 476. l7 Austral. J . Exp. Biol., 1936, 14, 323.18 Phytopath., 1935, 25, 601, 618. l8 W. M. Stanley, ibid., 1934, 24, 1055.20 Idem, ibid., p.1269.21 A. F. Ross and C. a. Vinson, Missouri Agric. Exp. Xta. Bull., 1937,22 Idem, Science, 1936, 83, 626.3 3 H, H. Thornberry, Phytopath., 1935, 25, 931.24 Contr. Boyce Thomps0.n Inst., 1936, 8, 335; 1937, 8, 446.No. 258430 BIOCHEMIS'TRY.expresses the view that this process of inactivation, which isinhibited by catalase, depends on the formation of an intermediateproduct (not dehydroascorbic acid) of a peroxide nature. It is ofinterest that neither the oxidation of reduced ascorbic acid by1 : 2 : 6-dichlorophenol-indophenol or potassium permanganatenor the autoxidation proceeding in alkaline solution in the presenceof hexoxidase provides conditions suitable for inactivation of thevirus. In this connexion A.M. Smith and W. Y. Paterson 25 recordthe significant observation that varieties of potatoes susceptible topotato mosaic virus disease show a general tendency towardslower ascorbic acid contents than do resistant varieties, althoughin individual varieties diseased stock contained larger amounts ofascorbic acid than did the healthy ones.Virus extracts lose much or all of their infectivity after treatmentwith salts of mercury, copper or silver in higher than germicidalconcentrations. In the case of copper sulphate and mercuricchloride dilution of the treated preparations (approximately I in100) results in complete reactivation of recent, but only partialreactivation of aged, preparations. Highly purified protein failedto recover after treatment with silver nitrate.Recent investigationsof these effects by J. C. Went 26 and by J. Caldwell 27 confirm theview that the action of these salts is primarily on the protein ratherthan on the cellular contents of the host plant as formerly suggestedby Stanley.It is a matter of practical interest that virus which may bewashed out from decaying plants into the soil becomes slowlyinactivated therein, aeration and drying being potent factors inthis respect. In undecayed plant tissue, however, neitherdesiccation nor freezing affects the activity of the virus.28Other Viruses.-The above considerations have concerned tobaccomosaic virus only, since this, of the many virus diseases known,has received by far the most extensive investigation on thebiochemical side.Other viruses tend to show similar properties inso far as these are as yet recorded. Much evidence indicates,however, that each virus is not necessarily a distinct entity. Thustobacco mosaic infects not only different varieties of tobacco andeven other species of the same botanical family, but in suchunrelated species as phlox and petunia, in which the normalproteins are widely different, mosaic-infected plants are found tocontain a high-molecular protein indistinguishable from that oftobacco mosaic. More extensive examination in the case of25 Biochem. J., 1937, 31, 1992.2 7 Proc. Roy. Soc., 1936, B, 119, 493.28 I. H. Hoggan and J. Johnson, J. Agrie. Res., 2936, 58, 2'91.26 Phytopath. Z., 1937, 10, 480POLLARD : PLANT.431tomato mosaic by HI. S. Loring 29 shows the indisputable identityof the protein with that of tobacco mosaic.On the other hand, Stanley 30 has isolated from Turkish tobaccothe protein associated with the yellow or aucuba-like mosaic disease.This is very closely related to the ordinary mosaic protein, butforms larger crystals and has a higher molecular weight and higherisoelectric point. It is similar to the ordinary mosaic protein inX-ray pattern31 and is inactivated by similar means. F. C. Bawdenand N. W. Pirie32 find that the protein occurring in mosaic-infected cucumber plants also possesses many of the propertiesof tobacco mosaic protein, but exhibits characteristic differences.The crystalline protein occurring in tobacco “ ring spot ” differsrather more markedly from the mosaic protein, but nevertheless isdefinitely of the same general Tobacco plants aresusceptible to at least four forms of mosaic, the ordinary variety,aucuba mosaic, “ mashed ” mosaic, and a single lesion strain, eachtending to induce the formation of a protein slightly different fromthe others.Inoculation of healthy plants with mixed viruspreparations or secondary inoculation of plants already infectedwith another virus usually results in the gradual dominance of oneof the forms 34 with a corresponding modification of proteinstructure. A form of “mutation ” among the virus proteinstherefore seems likely.Serological.-Essential differences between virus proteins demon-strated by physical or physicochemical means, in some cases maybe more definitely expressed in serological tests.Sera of animals obtained after injection of solutions of tobaccomosaic protein give a precipitin reaction with solutions of theprotein containing as little as g., with the juice from infectedplants but not with that of healthy plants.35 Chemically inactivatedprotein also produces an antiserum causing precipitation ofsolutions containing g.of active or inactivated protein.Inactivation, therefore, although modifying the chemical propertiesof the protein and its infectivity, does not necessarily destroy itsimmunological proper tie^.^^ F. C. Bawden and N. W. Pirie,37 inexamining cucumber viruses, obtained anti-sera giving specific29 H. 8. Loring and W.M. Stanley, J . Bid. Chem., 1937, 117, 733.3O Ibid., p. 325.31 R. W. G. Wyckoff and R. B. Corey, J . Biol. Chem., 1936, 116, 57.3a Nature, 1937, 139, 546.33 W. M. Stanley and R. W. (3. Wyckoff, SC~EYW, 1937,55, 181.94 H. H. McKinney, ibid., 1935, 82, 463.a5 W. M. Stanley, ibid., 1935, 81, 644.36 Idem, W., 1936,83, 626; Phytqvath., 1935, 25, 899.Nature, 1937, 139, 546432 BIOCHEMISTRY.precipitates with Q x 10-6 g. of the protein and point out that onlythose proteins serologically related to tobacco mosaic proteinexhibit anisotropy of flow and form spontaneously birefringentsolutions. Not all viruses induce precipitin reactions : those ofpeach “ yellows,” potmato leaf roll, bean mosaic, and tomato spottedwilt apparently fail in this respect.According to K. S. Chester 38serological activity in viruses is to be associated with relativestability to ageing and to temperature inactivation. On the basisof reciprocal precipitin reactions it now seems possible to classifymany viruses into groups according to their ability to producedefinite group-specific precipitins. Much remains to be done inthis connexion, but evidence already exists indicating that groupspecificity in viruses may ultimately be correlated with thestructure of the high-molecular protein.Apart from its significance in relation to virus diseases as such,current work on this subject brings out a, fundamental point ofmuch interest, vix., that physiological properties hitherto associatedwith living organisms can now be reproduced by a complex proteinmolecule. On this point Stanley 39 comments, “ It is possible thatby virtue of its size, it (the protein) is enabled to possess sufficientorganisation within the molecule to endow it with such properties(of living things).As such it would form a link between the typeof organisation within the molecule with which chemists haveconcerned themselves and the type of organisation within the cellwith which biologists have been concerned. . . , Infection may beregarded as the introduction of a few molecules of a virus proteininto a susceptible host. These few molecules appear to have theability to direct the metabolism of the host so that it produces, notnormal protein, but more of the virus protein.”Biochemistry of Certain Bacteria.The many-sidedproblem of the carbon metabolism of these organisms has beencarried forward by H.Gaffron40 in the case of the red sulphurbacteria Thiocystis. These organisms assimilate carbon dioxide indaylight but not in darkness even in the presence of hydrogen.When the cells have accumulated considerable amounts of sulphur,the evolution of carbon dioxide sometimes observed results fromsecondary metabolism of carbonaceous material. In darkness thebacteria produce hydrogen sulphide at the expense of organicreserves. This is utilised in the subsequent assimilation of carbondioxide in daylight (2C0, + H,S + 2&0 --+ 2CH,O + H,S04).Sulphur Bacteria.-Nutrition and metabolism.38 Phytopath., 1937, 27, 124.40 Biochem.Z., 1934, 269, 447; 1935,270, 1.39 Arner. J . Bot., 1937, 24, 59POLLARD : PLANT. 433Unlike the purple bacteria, Thiocystis is unable to utilise organicsubstances as hydrogen donators in the hydrogenation of carbondioxide, but can effect the reduction of sulphates to sulphides indarkness when supplied with sodium butyrate.In the case of the purple bacteria, Gaffron41 shows that underanagrobic conditions assimilation of carbon dioxide occurs in thepresence of salts of the fatty acids to extents which increase withthe molecular weight of the acid. I n an atmosphere of hydrogen,nitrates, lactates, pyruvates, and glycollates as well as carbondioxide are reduced. These organisms are apparently able toutilise the energy of infra-red light and also to assimilate oxygendirectly.According to P. 9. Roelofsen42 the purple bacteriaappear to assimilate carbon dioxide in darkness in the presence ofhydrogen, the absorption of hydrogen being proportional to theconcentration of carbon dioxide present under these conditions.Other assimilable substances are, however, necessary for thenormal growth of the organism. Oxidisable sulphur compoundssupplement the action of organic hydrogenators and increase therate of assimilation of carbon dioxide. Observed changes inoxidation-reduction potential with alteration of light intensity orconcentration of hydrogen donators are in conformity with thetheory that the bacterial suspension acts substantially as aphotoelectric half -cell. Further observations on this point byD.I. Saposhnikov43 show that the photoreduction of carbondioxide by purple sulphur bacteria is optimal a t rH 14-16 andthat one molecule of carbon dioxide is reduced for each quantumof light energy absorbed. It is noteworthy that in the case of s nentirely different organism, Streptococcus varZans, measurements ofthe photoassimilation of carbon dioxide and hydrogen by C. 8,French 44 indicate that four light quanta are required per moleculeof carbon dioxide.An interesting instance of an organism which can but does notof necessity utilise sulphur compounds in carbon assimilation isexamined by H. N a k a m ~ r a . ~ ~ The sulphur-free purple bacteriumRhodobacillus palustris develops in light or in darkness in thepresence of oxygen, but anaerobic growth is possible only in light.The assimilation process in light appears to involve the productionof an intermediate product which is subsequently decomposed inan oxidative respiration process. Since respiration does not occurin darkness, an external source of oxygen is necessary for41 Biochem.Z . , 1935, 275, 301.42 Proc. K. Akad. Wetensch. Amsterdam, 1934, 37, 660.43 Biochimia, 1937, 2, 181.45 Act4 Phytochim., 1937, 9, 189, 231.44 J . Gen. Physiol., 1937, 20, 711434 BIOCHEMISTRY.continuance of assimilation. In the presence of hydrogen sulphideand certain fatty acids, sulphur and oxidation products of the acidsare formed. It is shown that the primary reduction of carbondioxide takes place a t the expense of the hydrogen of water, theresidual hydroxyl (or hydrogen peroxide) reacting with hydrogensulphide or with hydrogen produced by dehydrogenation of thefatty acids.Specific dehydrogenases of fatty acids are present inthe organisms. The fundamental photosynthetic process, therefore,is identical with that in higher plants, in that carbon dioxide andwater are involved, and hydrogen sulphide and fatty acids areconcerned only in subsequent processes, without being essential forgrowth. In the case of Rhodospirillum giganteurn hydrogensulphide or another oxidisable sulphur compound is essential in theautotrophic culture to act as a hydrogendonator in the hydrogenationof carbon dioxide in light. In heterotrophio cultures organic acidsmay act as carbon sources, but growth is accelerated by additionof thiosulphate.The effects of different sources of sulphur on the growth of thepurple bacterium Ectothiorhodospira mobile are examined by V.A.Tschesnokov and D. I. Saposhnik~v.~~ The optimum p , forgrowth is found to be inversely related to the state of oxidation ofthe source of sulphur, e.g., NaHSO,, 7.4; Na,S,O,, 7.5; S, 8 - 5 ;Na,S, 9.0. This effect is ascribed to differences in Eh set up in themedium by the various sulphur compounds.In a series of papers R. L. Starkey records an investigation ontwo other species of sulphur bacteria, Thiobacillus thioparus andT . novellus, both of which are characterised by their ability toconvert thiosulphate into a mixture of sulphur and sulphate, othersulphur compounds being only slowly, if at all, attacked.In thecase of T. nowellus the action on thiosulphate is marked by anincreased acidity in the substrate, and is accordingly favoured byan alkaline and buffered medium. The two species are furtherdistinguished by the fact that T. thioparus can utilise nitrogen onlyin the form of ammonia, nitrite or nitrate, whereas organic formsof nitrogen are effective for 2’. n o v e l l ~ s . ~ ~ The production ofthionic acids by these organisms is now regarded as the result ofsecondary reactions, and not as an essential part of the principaltransformation .48Although the yellow substance produced by these bacteria fromthiosdphate is very generally regarded as sulphur, 0. von Deines 49had expressed the view that in the case of the larger sulphurbacteria the corresponding substance was really a polysulphide‘ti Bio&mh, 1936, 1, 63, 157.47 J. Bact., 1934, 28, 365.49 Naturwk., 1933, 21, 873. J . @en. Physiol., 1935, 18, 325POLLARD : PLANT. 435of very high sulphur content, on the ground that treatment withacid under reduced pressure yielded hydrogen sulphide. AlsoA. Monti showed that endocellular c'~uIphur droplets " producedsilver sulphidc from the nitrate, although reactions with lead andmercury salts were less definite. After a close examination of thesulphur deposits of T. thioparus Starkey 51 concludes that thesereally consist of elementary sulphur free from sulphide. He finds,however, that under certain conditions T.thioparus and T. novellusmay produce small amounts of hydrogen sulphide by hydrogenationof the initial sulphur accumulation. It would appear that thishydrogenation occurs within the bacterial cells and does not precedethe entry of sulphur into the organism.Among newly recorded sulphur transformations effected bybacteria may be mentioned the production of sulphur from 1-cystineby Achronzabacter cystinovorurn (nov. sp.) when supplied with noother source of carbon, nitrogen, or sulphur,S2 and certain activitiesof a thermal spring bacterium of the Sulphomonas thiooxidansgroup. According to 0. Baudisch, this organism, which producessulphuric acid from sulphur, is extraordinarily resistant to this acidand continues to multiply in N-solutions.I n older cultures aB~-solution of sulphuric acid may be produced in the substrate.Reduction of sulphur to hydrogen sulphide or to a thiol compoundappears to precede the oxidation process. When grown indarkness with a low oxygen tension in cultures containing thymineglycol, the bacterium produces a characteristic red pigment inthe presence of acid. It appears probable that the glycol firstloses water, yielding CO<NH.CH(~H)>C~CH~, NH- co two molecules of, ,which unite to produceoxidation of which yields the red dyePigments of purple bacteria. Purther examination of thecarotenoid pigments of the Bhodovibris by B. Karrer and U.Solmssen 53 has resulted in the isolation of five pigments, zlix.,rhodoviolascene, C42HB002, probably a, dimethyl derivative oflycopene, xhodovibrin, a polyene alcohol, rhodopurpurene, ahydrocarbon, C#&56(58), resembling but not identical withlycopene, rhodopin, an unsaturated substance having one hydroxyl50 Boll.SOC. itctl. Biol. sperirn., 1935, 10, 690.5 1 J. Bact., 1937, 33, 545.68 Helv. Clvim. Acta, 1935, 18, 306; 1936, 19, 3, 1019.52 Svensk Kern. Tidslcr., 1935, 47, 191436 BI 0 CHEMISTRY.group and probably 12 double linkings, and an amorphousflavorhodin, probably a hydrocarbon. From the sulphur-freepurple bacteria E. Schneider 54 has isolated two carotenoids, oneresembling lycopene and the other similar to photoxanthene, theratio of the former to the latter being 0.6. Comparison with theamounts of bacteriochlorophyll previously examined 55 shows theratio of chlorophyll : carotenoids in these organisms to beapproximately 2.75, a value of the same order as that obtaiiiingin the chloroplasts of higher plants.Schneider indicates thecarotenoids are concerned in carbon assimilation.From XpiriZEum rubrum C. B. Van Niel and J. H. C. Smith 56have obtained a purple pigment, spiriZEoxanthin, CP8HS603, a highlyunsaturated substance probably containing an active hydroxyl butno keto-group.An excellent survey of the activities of the sulphur bacteria byH. J. Bunke appeared in 1936.57Marine Bacteria.-A notable interest in the bacterii inhabitingsea water and sea-bottom muds has become apparent in recentyears. Much of the current work is concerned with nutritionaland environmenfal conditions which control t'he distribution ofvarious types of organisms.Sea water contains a much smallerbacterial population than does fresh water, soil, etc. S. A.Waksman and M. Hotchkiss 58 ascribe this to relative deficiency ofnutrients and energy sources, e.g., H,S, S, H,, NH,, NO,, CH,, and,perhaps more notably, to the activity of predatory protozoa, e.g.,nannoplankton. A change in biological equilibrium in sea water iseffected by alteration of the nutrient supply, of temperature, or ofthe state of aeration of the water. C. E. Renn 59 in the course ofsimilar observations emphasises the fact that the temperature of alarge proportion of the ocean is sufficiently low to be unfavournbleto bacterial multiplication and also that particulate nutrient materiallikely to encourage the formation of bacterial colonies graduallysettles to the sea bottom, carrying its bacterial population into anenvironment which in many cases is less suited to developmentthan that in which the initial colonisation occurred.Nitrifying,denitrifying, and nitrogen-fixing organisms are generally distributedin sea water, their proportions being largely influenced by theoxygen content of the water.60 I n an examination of the depth-5 6 Arch. Mikrobiol., 1935, 6, 219.54 Rev. Fac. Sci. Istanbul, 1936, 1, 74.55 2. physiol. Chem., 1934, 226, 221.57 D. 8. I. R., Chern. Res., Spec. Rept. No. 3, 48 pp.5 8 J . Bact., 1937, 33, 85; S. A. Waksman, Ecol. Monog., 1934, 4, 523.K g J . Bact., 1937, 33, 86.6o S.A. Waksman, M. Hotchkiss, and C. L. Carey, Biol. Bull., 1933, '75,137437 POLLARD : PLANT.distribution of bacterial nutrients in sea water A. Krogh 61 recordsthat the organic nitrogen and ca'rbon contents, probably the mostimportant nutrient factors likely to limit development, aresubstantially the same a t all depths. According to S. A. Waksmanand C. L. Carey G2 sea water contains sufficient dissolved organicmatter to carry an extensive bacterial population, but in manycases its utilisation is restricted by the inadequate oxygen supply.Bacterial multiplication, oxygen consumption, and the liberationof assimilable nitrogen sources are found to exhibit a directrelationship. The utilisation of nitrogen-free organic matter, e.g.,glucose, added to sea water is apparently controlled by theavailable supply of nitrogenous matter.Urea-decomposing organisms occur near the shore, especially insurface muds, and are seldom found a t depths greater than 100 m.Three groups are differentiated by C.E. Zobell and C. B. Feltham,63viz., those producing ammonia, and those which do not liberateammonia from urea, both classes developing on media containingurea as sole source of nitrogen, and a third class which multiplyonly when other sources of nitrogen (ammonium salts, amino-acids,peptone) are present in addition to urea.Luminous marine bacteria apparently utilise amino-acids (alanine,leucine, glutamic acid) and require both potassium and sodium fortheir development. Luminosity is intensified by small amounts ofcopper, zinc, iron, or manganese salts, the numbers of organismsremaining unchanged unless calcium chloride also is added.The importance of solid surfaces for the development of ma'rinebacteria is demonstrated in another paper by Z0be11.~~ Storage ofsea water causes a marked increase in bacterial numbers, the extentof the increase being great in those vessels in which the total internalsurface exposed t o the water is high.Addition of solids t o thewater produces a similar effect and microscopic observation revealsa much greater concentration of bacteria on the solid surfaces thanin the free water. Oxygen consumption, denitrification, ammoni-fication and carbohydrate decomposition increase as the area ofsolid surface increases, although these biochemical changes probablyfollow rather than accompany the enlargement of the bacterialpopulation.The effect of the solid surface may be to concentratenutrients and exo-enzymes by surface adsorption or to bring about,in the interstices between the bacterial cells and the solid surface,localised changes of environment which retard the outward diffusionof enzymes from the cells or permit the establishment of pE or ofoxidation-reduction potentials more favourable to development61 Ecol. Mofiog., 1934, 4, 421, 430.83 Science, 1935, 81, 234.e2 J. Bact., 1935, 29, 531.G4 J . Bact., 1937, 33, 86438 BIOCHEMISTRY.than those in the free water. M7. W. Smith and C. E. Zobell65find that glass slides placed in sea water rapidly attract indigenousbut not foreign types of bacteria.An interesting examination of the bacterial population of thebottom mud of the Black Sea is recorded by T.Ginsburg-Karagitscheva and K. Rodionova.66 The mud contains considerableproportiona of bituminous hydrocarbons. Organisms isolatedinclude those which decompose cellulose, proteins, and fats andalso sulphate-reducing types. The course of fat decomposition isrepresented by an increase in the degree of saturation of the acidsand in the proportion of unsaponifiable matter. The nature ofthese organisms and their chemical activities suggest a closerelationship with those occurring in various oil-bearing strata.Production of Organic Acids by Bacteria.-Propionic acid. Themechanism of the transformation of glucose into propionic acid hasbeen extensively examined by C.H. Werkman and c0lleagues,~7according to whom the general scheme involves the changes :hexose --+ hexosephosphate --+ phosphoglyceric acid -+ pyruvicacid. Further changes may take either of two courses :No dead cells are attracted.-lactic acid --+ propionic acidacetic acid + CO,Pyruvic acidsuccinic acidpropionic acid + CO,Whether the hexosephosphate and phosphoglyceric acid representessential intermediates under all conditions is not quite clear.P. Chaix and C. Fromageot 68 demonstrate that the activity ofpropionic acid bacteria is stimulated by certain sulphur compounds,e.g., cystine, methionine, glutathione (oxidised or reduced), thiolacticand thioglycollic acids, Propionibacterium I I being apparentlyunable to act on glucose in the absence of sulphur cornp0unds,6~organic thiocyanates and hydrogen sulphide being particularlyactive in this respect.'O This action of sulphur compounds is65 J .Bact., 1937, 33, 87.H. G. Wood and C. H. Werkman, Biochem. J., 1936,30,618, 624; H. G.Wood, R. W. Stone, and C. R. Werkman, ibid., 1937, 31, 349; C. H.Werkman, R. W. Stone, and H. G. Wood, Enzymologia, 1937, 4, 11, 24; J.Bact., 1937, 33, 100, 102.6e Biochem. Z., 1935, 275, 396.6 s Compt. rend., 1936, 202, 983.7O Idem, Enzymologicc, 1937,1, 321.69 P. Chaix, &id., 1935,201, 857POLLARD : PLANT. 43srelated to the pE of the medium,71 and these authors suggest thatthe enzyme system of the living organism is inactivated byoxidation, the sulphur compounds exerting a protective action.7?The lactic-fermenting system is less affected by oxygen than thatof the other stages except that concerned in the decomposition ofpyruvate, which seems uninfiuenced.Several communications show the importance of nitrogennutrition and of certain growth factors in the activity of thepropionic acid organisms.Thus C. Fromageot and P. Laroux 73record that maize contains a growth factor necessary to enablecertain of this group of organisms to utilise ammoniacal nitrogen.It is also shown 74 that, whereas several species of Propionibacteriautilise ammonia (as ammonium acetate) in the presence of palentaextract, other species fail even under these conditions through lackof an essential growth factor; in nearly all cases the efficiency ofutilisation of ammoniacal nitrogen is dependent on the nature ofthe carbon source.V. G. Lava, K. ROSS, and K. C . Blanchard 75indicate that a factor stimulating the fermentative action ofpropionic bacteria also occurs in the vitamin-B, complex. WithPropimibacterium pentoaceticum fermentation is markedly increasedby small additions of orange juice, yeast extract or potato extract,the first two named appearing to contain the necessary growthfactors. The action of the latter is due to its ammonia andasparagine contents and is operative only in the presence of growthfactors occurring in extracts of maize or liver.76 According toH. G. Wood, E. L. Tatum, and W.H. Peterson 77 the factor appearst o differ, both chemically and biologically, from other knowngrowth factors, e.g., hepatoflavin, vitamin-B,, pantothenic andindolylacetic acids, inositol, nicotinamide, and the ‘‘ X’orogenesvitamin.” In another paper 79 it is recorded that certainstrains of these bacteria producing weak growth in the absence ofamino-acids develop freely and produce more acid when suppliedwith lactoflavin.Production of lactic and other acids. The production of opticallyactive lactic acids and the transformation of one isomeride into the71 P. Chaix and C. Fromageot, Bull. Soc. Chim. biol., 1936, 18, 1436.73 C. Fromageot and P. Chaix, Enzymologia, 1937, 4, 11, 769.73 Bull. Soc. Chim. biol., 1935, 18, 797, 812.74 C.Fromageot and E. L. Piret, Arch. Mikrobiol., 1936, ’7, 551.75 Philippine J . Sci., 1936, 59, 493.76 E. L. Tatum, W. H. Peterson, and E. B. Fred, J. Bact., 1936, 32, 157;77 Ibid., 1937, 33, 227.78 A. M. Pappenheimer, jun,, Bwchem. J., 1935, 99, 2057.7@ H. G. Wood, A. A. Anderson, and C. H. Werkman, PTOC. 800. Exp.also E. L. Tatum, H. G. Wood, and W. H. Peterson, ibid., p. 167.BWZ. Med., 1937, 36, 217440 BIOCHEMISTRY,other by bacteria have long proved a source of interest. Recentwork by H. Katagiri and K. Kitahars 80 shows that S. lactis bulgarisproduces relatively more of the d- than of the l-acid even when thedl-acid is added to the fermenting glucose medium. On the otherhand, Lactobacillus pentoaceticus gives the dl-acid from glucose, andwhen either active form is added to the substrate the final productis still the inactive form.The same authors also record theracemisation of the active acids by Clostridium acetobutylicum, anaction ascribed to the presence of the enzyme racemiase. That Rand S forms of individual species may produce acids of differentoptical properties is shown by L. M. Kopeloff and N. Kopeloff.*lThe X forms of L. acidophilus and L. bulgaricus yield d-lactic acid,whereas the R forms produce the dl-acid for some time, althoughthe latter organism begins to produce d-acid in older cultures.L. G. Longsworth and D. A. McInnes,S2 in an investigation ofthe activities of L. acidophilus in media mainta.ined at constantpH, find that acid yields are highest with low pH and that for agiven pH level the production of acid reaches a minimum when theoxidation-reduction potential of the culture is high.The rates offermentation and of growth a t a constant pE tend to be inversely1-elated.8~ Conversely the growth of the culture is accompaniedby an increased Eh, which finally attains a constant andcharacteristic value.84 In a somewhat similar investigationR. W. H. Gillespie and L. P. Retger 85 show that the reversion ofEn of the culture during growth coincides with the period of mostrapid change of pE. I n buffered media these authors record thatthe final Eh reached is sufficiently specific (cf. Longsworth andMcInnes, above) to permit differentiation of different strains oforganisms, e.g., oral, intestinal, etc.Growth-promoting substances are essential t o the developmentof lactic acid-producing bacteria, streptococci included.Accordingto S. Orla-Jensen 86 the active substance is alkali-stable, is relatedto bios, and is probably pantothenic acid. In some caseslactoflavin also is required and for this purpose cannot be replacedby glutathione. In the case of L. delbriickii, E. E. Snell, E. L.Tatum, and W. H. Peterson 87 find that active growth in caseinhydrolysates containing tryptophan requires the presence of twounknown growth factors : one, possibly an acid of low molecularweight, occurs in the Neuberg filtrate of water extracts of potato,80 J . Agric. Chew. SOC. Japan, 1936, 12, 96.81 Ibid., 1935, 29, 695.84 Ibid., 1936, 32, 567.86 Nature, 1935, 135, 915; also S.Orla-Jensen and A. Snog-KjEr, Zentr.Bakt. Par., 1936, 11, 94, 434.87 J . Bact., 1937, 33, 207.J . Bact., 1937, 33, 331.83 Ibid., 1936, 31, 287.85 Ibid., 1936, 31, 14POLLARD : PLANT. 441and the other, a basic substance, is present in peptone. Bothfactors are found in liver extracts and are hydrolysable by acids.A. K. Sain 88 had previously observed that acid production by L.caucasica was stimulated by a dialysable, thermostable constituentof aqueous extracts of beans.Factors influencingthe production of gluconic acid by B. gluconicurn are examinedby S. Hermann and P. N e u s ~ h u l . ~ ~ The yield of acid variesconsiderably with the concentration of glucose supplied and withthe temperature of fermentation.In general a rise in temperaturediminishes the yield (yo) and, simultaneously, the optimum sugarconcentration. This organism also effects the oxidation of mannoseto mannonic acid, yields of 60-70y0 being obtainable. Furtheraction of B. gluconicum on calcium gluconate produces smallamounts of 2- and 5-ketogluconate and an aldehydogluconic acid,probably Z-guluronic acid. The last is also a product of the actionof B. xyZinzcrn on gluc0se.~1 T. Takahashi and T. Asai92 find,among the acid-producing bacteria of fruits, species of the gluconicacid type which convert galactose into galactonic and comenicacids, and another, Gluconoacetobacter cerinus var. ammoniacus,which oxidises glycerol to an unidentified ketogluconic acid,probably via dihydroxyacetone and succinic or glycollic acidwithout the intermediate production of glyceric and acetic acids.I n subsequent work Asai 93 shows that the optimum pH for gluconicacid production by this group of organisms is less than that formultiplication, and further that the typical biochemical changesbrought about are related to the optimum growth temperatures ofindividual species.Those growing freely a t relatively hightemperatures oxidise glucose to gluconic or glycuronic acid andacetic acid to carbon dioxide and do not act on glycerol or mannitol.Low-temperature species produce glycuronic or S-ketogluconicacid from glucose, kojic acid from niannitol (via fructose),dihydroxyacetone from glycerol, and do not ferment acetic acid.Acetone-Butanol Fermentation.-The mechanism of this type offermentation offers a problem of considerable complexity, sincethe nature and proportion of the products exhibit wide variationwith conditions of fermentation and with the nature of thecarbohydrate source.Thus K. Bernhaixer and K. Kurschner 94Bacteria producing gluconic and related acids.88 Milcrobiologiya, 1933, 2, 266.90 S. Hermann and P. Neuschul, BUZZ. SOC. Chim. bid., 1936, 18, 390.91 K. Bernhrtuer and K. Irrgang, Biochem. Z . , 1935, 280, 360; H.92 J . Agric. Chem. SOC. Japaw, 1934, 10, 604.93 Ibid., 1935, 10, 50; 11, 331, 337, 499, 610, 674.04 Biochem. Z., 1935, 280, 379.89 Biochem. Z., 1936, 287, 400.Bernhauer and B. Gorlich, ;bid., p. 367442 BIOCHEMISTRY.record that CE. butyricus in fresh cultures converts acetic acidalmost quantitatively into acetone, but in later stages yieldsincreasing amounts of ethyl alcohol.Butanol production fromstarch appears to take place via the intermediate formation ofbutyric acid. The suggestion that acetaldol or P-hydroxybutyricacid is a precursor of butyric acid in this process is negatived bythe fact that these compounds do not yield butyric acid whenadded to the actively fermenting cultures. On the other hand,addition of crotonic acid resulted in its partial transformation intobutanol with simultaneous formation of acetone and carbondioxide.In a subsequent investigation K. Bernhauer, A. Iglauer, W.Groag, and R. Kottigg5 observe that the presence of excess ofcalcium carbonate in the cultures alters the proportions if not thecharacter of the principal products, in general favouring theformation of butanol and butyric acid at the expense of acetone,acetic acid, and ethyl alcohol.Under these conditions butaldehydeis largely converted into butanol, whereas pyruvic, crotonic, andlactic acids still produce large amounts of acetic acid. Althoughthe presence in CZ. acetobutyZicum of an enzyme system capable ofreducing propionic and butyric acids to the corresponding alcoholsis fairly well established, the acceptance of butyric acid as anintermediate in the normal fermentation is by no means general.96A. Janke and V. Siedler 97 advance evidence that the formationsof butanol and of acetone by B. acetobutylicum are independentprocesses.Suspensions of washed bacilli at pE 6.0 producebutanol, butyric and acetic acids and ethyl alcohol but no acetone,but convert aldol into butyric acid without the production ofbutanol or acetone. Moreover, under these conditions acetone isnot formed from acetic acid, nor butanol from butyric. Reductionof butyric acid to butanol may occur outside the cell.Weizmann’s strain of CZ. acetobutylicum offers another exampleof the necessity of a growth-substance in association with anamino-acid for the development of bacteria. In this case,asparagine together with a constituent of yeast autolysate appearsto be essential. The active substance is neither lactoflavin norcozymase and is possibly one which is not usually included in thiscategory of biocataly~ts.~~In the commercial production of these solvents from maize mashit is found that CZ.acetobutylicum can utilise xylose, if this does not95 Biochem. Z., 1936, 287, 61.96 B. Rokusho, J . Agric. Chern. SOC. Japan, 1936, 12, 639.87 Biochem. Z., 1937, 292, 101.98 C. Weizmann and B. Rosenfeld, Biochem. J., 1937, 31, 619POLLARD : PLANT. 443exceed 40% of the mash mixture, and still produce high yields.99Bcetoin, probably formed by condensation of two molecules ofacetaldehyde, appears to be an intermediate product in theconversion of starch into acetone and butanol by B. granulobacterpectinovorunz .IBiochemistry of iioulds.Mineral Nutrition of Aspergillus niger.-The action of pota.ssiumin the nutrition of moulds appears to be directed, as in the caseof the higher plants, towards regulation of the carbohydratemetabolism.Additional evidence on this point is given by 0.Kauffmann-Cosla and R. Brull,2 who, using A . niger on Raulin'smedium, show that it exerts a catalytic effect on celluloseproduction and simultaneously inhibits the formation of lipinsfrom carbohydrates. No influence on the course of nitrogenmetabolism was apparent. A. Rippel and G. Behr3 examine theenergy relationships of the mould grown in media containingvarious levels of supply of potassium. An optimum concentrationof potassium is established, below which the energy consumptionper gram of mycelium produced falls steadily.Relationships between the development of A . niger and thesupply of magnesium form the subject of two pa'pers by J.Lavollay and F.Lab~rey.~ I n Raulin's medium growth dependson the concentration of magnesium in the medium rather than onthe absolute amount supplied. Pigmentation of the myceliumreaches a maximum when the concentration of magnesium in thesubstrate is less than the optimum for growth and is apparentlyaffected by the presence of ascorbic acid, which tends to restrictthe production of pigment. Ascorbic acid increases mycelial growthto extents which depend on the concentration of magnesiumavailable.*Secondary Nutrients.-The influence of zinc on the developmentof A . niger is directed primarily on vegetative growth, and modifiesthe course of metabolism only as a secondary effect. Therespiratory activity undergoes no change.G. M. Vassiliev showsthat with strains producing gluconic acid (alone or with citric acid)zinc restricts acid production, but ha's a stimulatory effect on otherv9 L. A. Underkofler, L. M. Christensen, and E. I. Fulmer, Id. Eng. Chem.,1036, 28, 350.1 I. Yamasaki and T. Karasima, Ernzymologia, 1937, 3, 271.2 Bull. SOC. Chim. biol., 1937, 19, 137. Arch. Milcrobiol., 1936, 7, 315.Compt. rend., 1937, 204, 1686; 205, 179.Arch. Mikrobiol., 1935, 6, 250. * H. N. Barham and B. L. Smits (p. 448) also report that pigmentationof A. flavus in xylose media is also influenced by the concentration ofmagnesium in the substrate444 BIOCHEMISTRY.strains which produce citric acid only. 0. Kauff mann-Coslal andR. Briill also observe that zinc deficiency results in n diminutionof synthesis of carbohydrates and also that of lipins and proteins.It is usually assumed that iron, unlike zinc, is concerned in thefructification rather than in the vegetative growth of A.niger.According to F. G~llmick,~ however, both zinc and iron, and alsocopper, may, under certain conditions, stimulate both inycelialgrowth and spore formation. Inter-relations between zinc andiron in respect of fungal activity are further illustrated by theobservation that iron partly counteracts the inhibitory influence oflarger dosages of zinc on fructification, but tends to increase itsaction on vegetative growth, Iron also diminishes the toxic effectsof cadmium salts.The inferior growth of A.niger on media containing suga,rpurified by alcohol (to remove bios co-enzyme R, etc.) is ascribedby R. A. Steinberg to the incidental removal of traces of zincand molybdenum salts during the purification process. It is alsosuggested that the stimulation of growth observed on the additionof yeast, malt, etc., to culture media, normally to supply accessorygrowth substances, is in reality due to the heavy-metal salts whichthese materials contain, and that growth-promoting substancesmay not be essential for the growth of the mould.Steinberg records the influence of varying proportions of zinc, iron,manganese, and copper on the growth of A . niger and indicates thatoptimum concentrations are in each case greater in media havingpH > 8. In media containing all four elements, sulphuric acid,sodium sulphate, and sodium sulphide induce a further increase ingrowth.Subsequent partial precipitation of the sulphate bybarium (itself having very little toxic action) induces deficiencysymptoms resembling those due to deficiency of nitrogen,phosphorus, magnesium, iron, or zinc. The importance of sulphurin the growth of A . niger is shown by A. Rippel and G. Bohr,lO whorecord that in potassium sulphate media the intake of sulphur ishigh and that autolysis of the mycelium results in the liberation ofcorrespondingly large proportions of organic sulphur compounds.That the intake of sulphur under these conditions is not a necessaryresult of the assimilation of potassium is shown by the fact that,when potassium is supplied as chloride instead of sulphate, nocorrespondingly large intake of chlorine occurs.A further comprehensive study l1 of the relative stimiilntory andI n other papersBull.XOC. Clziw~ b i d , 1935, 17, 1828.7 Zentr. Bakt. Par., 1936, 11, 93, 421.6, Amer. J . Bot., 1936, 23, 227; Bot. Gr'az., 1936, 9'7, 666.lo Arch. Mikrobiol., 1936, 7, 584.J . Agric. Res., 1936, 52, 439.l1 Ann. Reports, 1935, 32, 442POLLARD : PLANT. 445toxic effects of numerous metallic compounds on the growth of A .niger is reported by K. Pirschle.12 In general, metals in the anionicform of combination are more toxic than when they form thecations of salts. I n the cases examined, metals forming more thanone series of salts are more toxic in the higher state of valency.Production of Citric and Oxalic Acids by Aspergillus.-As notedin previous Reports,13 the conversion of sugars and of other organicacids into citric and oxalic acids, although examined extensivelyfrom many viewpoints, still lacks an explanation of its mechanismwhich covers anything approaching all the observed facts.Published work during the past two years has perhaps tendedmore to refute certain earlier theories than to contribute new ones,although it has in many respects clarified a number of points onwhich experimental evidence appeared contradictory.Thus T.Chrzpzcz and M. Zakomorny,14 in pursuance of thetheory that the transformation hexose + citric acid occurs byway of ethyl alcohol and acetic acid, report a further examinationof the conversion of calcium acetate into citric acid, and show thatthis change is favoured by the addition of small amounts of sugarto the medium, irrespective of the formation of oxalic acid.Enfeebled mycelium produces little citric but much oxalic acid.These authors reject the view that citric acid is derived frominycelial substance and also fail to detect the presence of aconiticacid, suggested l5 as an intermediate product in the formation ofoxalic acid.I n a further paper l6 it is shown that the addition ofsodium E-malate to calcium acetate media increases citric acidproduction, and that further increases occur if both sugar andmalate are present. The theory is advanced that both rna'lic andacetic acids are concerned in the conversion of sugar into citricacid. Chrzqszcz and Zakomorny also find l7 that prolongedpropagation of the mould leads to a form of degeneration markedby a diminished ability to produce citric acid, which is more andmore replaced by oxalic acid.Such degenerate strains regain, a tleast temporarily, their citric-producing power when propagated onglucose or sucrose media, the regeneration being favoured by thepresence of malt wort containing peptone. Guanidine and ureaappear to increase the formation of oxalic acid.R. Bonnet and J. Jacquot,l* following up earlier work,demonstrate the influence of the nitrogen nutrition of the mould12 Plccnta, 1935, 24, 649.14 Biochem. Z., 1936, 285, 340.15 K. Bernhauer and F. Slanina, Biochem.Z., 1933, 264, 109; 1934, 274, 97.16 Ibid., 1936, 285, 348.18 Compt. rend., 1935, 201, 1213.la Ann. Reports, 1935, 32, 444.Ibid., 1937, 291, 312446 BIOCHEMISTRY.on acid production, and show that with peptone or amino-acids asnitrogen source both oxalic and citric acid are formed, growth andyield of citric acid reaching a maximum after about four days andsubsequently remaining practically unchanged. Oxalic acid con-tinues to be formed over a considerable period. All commonsugars (lactose excepted) yield both acids in nitrate media, butoxalic acid was absent from all cultures in which nitrogen wassupplied as ammonium salts.The latter observations suggest that the proportions in whichcitric and oxalic acids are produced by A. niger are influenced bynutritional conditions and by the physiological state of the culture.Further evidence on this point is presented by R.Baets16,1g whoreports maximum yields of citric acid in 0.2% ammonium nitratemedia containing ZOyo of sucrose at pE 1~8-2.2. A similar resultis recorded by S. A. Barinova.20 Prolonged fermentation athigher temperatures (30") with increased concentrations ofammonium nitrate in the medium diminishes citric acid formationand results in the appearance of oxalic and gluconic acids.E. M. Johnson, E. C. Knight, and T. K. Walker 21 examine acidproduction from a different angle. Addition of small amounts ofsodium iodoacetate to mycelium of A . niger in glucose mediaincreases the rate of utilisation of sugar and the yield of acid.Larger concentrations of iodoacetate, sufficient to suppress sporeformation, also prevent the anaerobic production of ethyl alcohol,but citric acid accumulation remains unaffected.Citric acidproduction may not involve an alcoholic type of fermentation.An interesting study of the carbon balance of A . niger in relationto the glucose-+ citric acid mechanism is recorded by P. A.Wells, A. T. Moyer, and 0. E. Yields of citric acid andcarbon dioxide are found to be incompatible with any chemicalmechanism analogous to the breakdown of glucose in alcoholicfermentation, with any process involving decarboxylation ofpyruvic acid, or with Emde's mechanism.The eifect on yields of acid of neutralising the culture mediumduring fermentation is emphasised by V.A. Kirsanova,23 whofinds that with all strains examined on sucrose media acidformation ceases at pH < 3 and > 8. Addition of alkali duringfermentation increases the final yield of acid, citric, oxalic, andgluconic acids all being concerned. The efficiency of neutralisingagents was in the order CaCO, < NaOH < Na,CO,. When thereaction is thus controlled, the relative yield of oxalic acid declines19 Natuurwetensch. T;jds., 1937, 19, 5.20 Zentr. Bakt. Pm., 1936, 11, 95, 63.za J . Amer. Chem. SOC., 1936, 58, 555.21 Biochem. J., 1937, 31, 903.23 Biochimia, 1936, I, 426POLLARD : PLANT. 447with increasing time of fermentation. Frequent change of thepellicle results in increased yields of citric acid, and the interestingpractical fact emerges that with 35% sucrose solutions as much as90% of the theoretical yield of citric acid may be obtained bymaintaining the pE of the culture within the range 4-6The proposed mechanism of the production of oxalic acid viaformic acid2* is to some extent challenged by V.S. Butkevitschand L. K. Osni~kaja,~~ who observe that at 30” the yield of oxalicacid is’unaffected by the concentration of formate in the mediumand is only slightly altered by replacement of the formate bysodium carbonate. Transference of the mycelium to disodiumhydrogen phosphate buffer solutions results in a rapid accumulationof oxalic acid (up to 70% of the loss in weight of the mycelium) ina few days. The now exhausted mycelium is incapable of producingoxalic acid from formate, but when placed in sodium acetatesolution rapidly produces oxalic acid without change in its ownweight.It is suggested that oxalic acid is normally produced frommycelial substance and not from the formate, and that acetatemay be concerned in the process. This recalls Challenger’s earliertheory that the change acetate-+ oxalate takes place with theintermediate production of glycollic and glyoxylic acids. Such amechanism is now opposed by T. A. Bennet-Clarke and C. J. LaTouche26 on the grounds that glycollic acid supplied directly toactive mould cultures was rapidly utilised, but no oxalic acid wasformed. Similar results with citric acid also ruled this out as anintermediate in oxalic acid productions.In a recent paper A.Allsopp 27 throws further light on a numberof controversial points. He demonstrates a reversible equilibriumbetween oxalic acid and the reserve carbohydrate (probablyglycogen) of the mycelium. Artificially increased amounts ofoxalic acid in glucose media disappear until the same level of acidis attained as is produced by the action of the mould on glucosealone. Addition of oxalacetic, malic, succinic, pyruvic, glycollic,and other 4-, 3-, and 2-C acids to starved cultures is followed byconsumption of the acids, without corresponding production ofoxalic acid. It is unlikely, therefore, that these acids areintermediate in oxalic acid production, as has been suggested byvarious workers from time to time. The formation of oxalic acidwhen salts of the various above-mentioned acids are added toculture media is explained by a disturbance of the glycogen +glucose + oxalic equilibrium by the “trapping” of oxalic acid24 Ann.Reports, 1935, 32,44A.26 Compt. rend. Acad. Sci. U.R.S.S., 1936, 1, 361.26 New PhytoJ., 1934, 54, 211. 2 7 I b X , 1937,38, 327448 BIOCHEMISTRY.by bases liberated as the anions are assimilated by the mould. I nthe case of oxalacetate, pyruvic acid and carbon dioxide are theprincipal products, and only at a much later stage is there anyproduction of oxalic acid, which, even then, is formed in amountstotally unrelated to the proportion of oxalacetate consumed. It isconcluded, therefore, that the source of oxalic acid is the glycogenor other reserve carbohydrate of the mycelium, and that the processoccurs via sugar (glucose, fructose, galactose, arabinose, and xyloseyield oxalic acid in starved cultures} and organic acids other thanthose referred to above.Among many acids examined by additionto starved cultures, only gluconic acid yielded oxalic acid. Thetheory is advanced that oxidation of the two end carbon atoms ofa sugar molecule containing a t least 5 C produces a keto-acid andby further hydrolysis, oxalic acid ; e.g., glucose ----+ gluconicoxidationhydrolysisacid j fructuronic acid- oxalic acid + 3 or 4-C residue.It is further shown that certain organic acids, e.g., lactic acid,inhibit the accumulation of oxalic acid in mould cultures, an effectwhich is not due merely to change of p,, since hydrochloric acidin amounts to produce similar pH changes has no inhibitory action.The observation, however, affords some explanation of theapparently contradictory results obtained in cultures t o whichvarious organic acids have been added.Fermentation of Pentoses and Other Substances by VariousAspergillus Xpecies.-T. Tadokoro,28 in an investigation of sugarfermentations by A .oryxce, finds that arabinose yields principallyformic, citric, and glycollic acids with smaller proportions o€oxalic and kojic acids and glyceraldehyde. From fucose areobtained formic, glycollic, and lactic acids. I n neither case wasacetaldehyde, acetone, acetic acid, or ethyl alcohol detected. Inthe presence of a hydrogen acceptor, e.g., methylene-blue, fucoseyields maleic in place of glycollic and lactic acids.29 From xylose,H.N. Barham and B. L. Smits30 obtained considerable amountsof kojic acid (the principal acid formed) by the action of A. jlavus,utilising appropriate nutritional conditions. Optimum yields areassociated with pH 2.5-3.5 and the use of ammonium salts ratherthan nitrate as nitrogen source. The presence of zinc salts,previously observed to stimulate the activity of the mould, has noinfluence on the yield of kojic acid and iron and calcium saltsexert an inhibitory action.J. Cheymol 31 reports the fission of a glucoside, verbenaloside28 J . Agric. Chem. SOC. Japan, 1935, 11, 167, 366.29 T. Tadokoro, Bull. Chem. Xoc. Japan, 1936, 11, 239.3O Ind. Eng. Chern., 1938, 28, 667.31 Bull. SOC. Chim biol., 1937, 19, 460449 POLLARD : PLANT.into verbeiialol and glucose, by A. niger and W. €3. Deys and M. J.Dijkman32 obtained gallic acid from theotannin in the presence ofsugars with the same organism. Other carbohydrate transforxn-ations recently examined include the production of d-mannitol byA . glaucus when supplied with glycerol as sole source of carbon.33Production of Fats and Sterols by Moulds.-The formation offatty matter in moulds is usually associated with high levels ofsupply of carbon and nitrogen in the nutrient and with rapidproduction of mycelium. Under these conditions protein synthesisis considerably restri~ted.3~ A summary of data illustrating therelation between nutrient conditions and yields of fat from mouldsand bacteria is given by W.Schwartz.35According to K. Taufel, H. Thaler, and H. Schreyegg36 the fatof certain species of Citrornyces contains principally oleic andlinoleic esters and lesser proportions of stearic and palmitic esters.No acids between C, and C,, are detectable. The unsaponifiablefraction includes ergosterol.The crude fat of Rhixopus japonicus contains the same principalfatty acids, but in rather different proportions (stearic and linoleicacids low) and also yields ergosterol with a rather larger proportionof fungister01.3~ A further examination 38 of sterol production byAspergillus Jischerei is reported by P. R. Wenck, W. H. Peterson,and E. B. who indicate a general inverse relation betweenthe rate of growth of mycelium and its sterol content.The lattertends to increase with the sugar content of the medium and reachesthe maximum when the nitrogen supply is low. %'ormation ofsterols appears to be accelerated during the autolysis of mycelium.Mycelium of Aspergillus sydowi contains 0.4-0.7 yo of phospholipins,chiefly lecithin and ke~halin.~ONew Products of Mould Metabolism.-Continued investigationsof the metabolism of moulds by Raistrick and his colleagues duringthe period under review include the examination of certain productsof ,4spergiZlus terreus. On glucose media containing potassiumchloride as chlorine source this organism produces two opticallyactive chlorine-containing substances, wix., geodin, C1,H,,O,CI,,32 Proc. K . Akad. Wetensch.Amsterdam, 1937, 40, 618.33 I. Yamasaki and M. Simomura, Biochem. Z., 1937, 291, 240.3Q H. Fink, G. Haesler, and M. Schmidt, 2. Spiritusind., 1937, 60, 74, 76,35 Angew. Chem., 1937, 50, 294.37 H. Lim, J . Pac. Agric. Hoklcaid~, 1935, 3'9, 165.38 See Ann. Reports, 1935, 32, 447.39 Zentr. Bakt. Par., 1935, 11, 92, 330.413 D. W. Woolley, F. M. Strong, W. El. Peterson, and E. A. Prill, J . Amer.81.30 Fette u. Seqen, 1937, 44, 34.Chem. Xoc., 1935, 57, 2689.REP.-VOL. XXXIV. 450 BIOCHEMISTRY.m. p. 235", a dibasic acid containing two methoxy-groups, anderdin, C16Hlo07C12, m. p. 229", also a dibasic acid but containingonly one methoxy-group. Substitution of iodide or bromide forchloride in the medium failed to produce corresponding halogenatedcompound^.^^ Geodin appears to be a methyl ether of erdin.42P.W. Clutterbuck, H. Raistrick, and 3'. Reuter43 have isolatedanother metabolic product of the same organism, wix., terrein,CsHloOI, m. p. 127", probably 2-hydroxy-3 : 5-oxido-4-propenyl-cycZopen%an- 1 -one.From Penicillium paEitans 5. H. Birkinshaw and H. Raistrick 44have obtained palitantin, C14H2a04, m. p. 163", an unsa'turatedsubstance containing an aldehydo- and two hydroxyl groups.Penicillic acid, CsHl0O4, produced by P. puberulum and P. cyclopiurn,is now shown 45 to be y-keto-P-methoxy-6-methylene-Aa-hexenoicacid, which can exist in both keto and enol forms :CH,:CMe*CO*C( OMe):CE*CO*OH f CH2:CMe* (OH)*C( OMe):CH*qOThe same workers also record *6 the isolation of terrestric acid, anethylcarolic acid:' from P.terrestre.Ravenelin, a yellow colouring matter of a somewhat unusualtype among natural products, wix., a hydroxyxanthone, probably1 : 4 : S-trihydroxy:3-methylxanthone, has been obtained 48 fromthe metabolic products of Helminthosporiurn ravenelii and H .turcicum.From Fusarium culmorum four new pigments are r e p ~ r t e d , ~ ~vix., rubrofusarin, ClsH120s, rn. p. 210-211" (one methoxyl group),norrubrofusarin, m. p. > 280", aurofusarin, CsoHzoOll,HaO, m. p.> 360" (2 methoxyls), and culmorin, C1,H2,O2, m. p. 174". H.Lim 60 records the isolation, from the constituents of Rhixopusjaponicw, of a new phosphoprotein, rhizopenin, which on hydrolysisyields considerable proportions of tyrosine and tryptophan and inwhich 5-6% of the total sulphur content is in the form of cystine.A brief review of twelve years' developments in the study of thebiochemistry of moulds, more especially of the work of H.Raistrickand co-workers, is recorded by P. W. Clutterbu~k.~~41 H. Raistrick and G. Smith, Bwchem. J., 1936, 30, 1315.42 P. W. Clutterbuck, W. Koerber, and H. Raistrick, ibid., 1937, 81, 1089.43 Ibid., p. 987. 44 Ibicb., 1936, 30, 801.45 J. H. Birkinshaw, A. E. Oxford, and H. Raistrick, ibid., p. 394.46 J. H. Birkinshaw and H. Raistrick, ibid., p. 2194.4 7 See Ann. Reports, 1935, 32, 447.48 R. Raistrick, R. Robinson, and D. E. White, Biochem. J., 1936,30, 1303.49 J. N. Ashley, B. C. Hobba, and H. Raistrick, ibid., 1937, 31, 385.W J .Fac. Agric. Hokkaido, 1935, 3'7, 165.51 J . SOC. Chem. Id., 1936, 55, 5511.F,-POLLARD : PLANT. 451Biochemistry of Certain A l g aNutrition and MetaboEis,m.-Recent communications 011 thissubject are mainly concerned with the assimilation of carbon andnitrogen and with the metabolic products. Among species ofChZoreZZu examined by T. D. B e ~ k w i t h , ~ ~ considerable differencesexist in ability to utilise various forms of nitrogen. Ampply ofwhole protein is not generally essential for development and one ormore of the simpler forms (peptone, asparagine, urea, nitrate, andammonium salts) are normally effective sources of nitrogen. H.Meyer 63 examines the growth of C . Zutesviridis in media containinga wide range of organic substances.Among the simpler aliphaticalcohols, aldehydes, and acids, the lowest member is toxic in eachcase, the second member is of high nutritional value, and highermembers are utilised less and less readily as the series is ascended.I n general iso- and unsaturated acids are toxic, but p-hydroxybutyricacid is readily assimilated. Hexoses form the best sources ofcarbon, and polysaccharides have a value which is closely dependentin the ease of their hydrolysis. According to Beckwith (Zoc. cit.)only maltose and glucose, among common sugars, favourproliferation in diffuse light.W. H. Pearsall and L. Loose 54 distinguish two phases in themetabolism of Chlorella vulgaris on glucose media. I n the firststage, i.e., that of exponential proliferation, the synthesis of proteinand of protoplasmic constituents predominates.I n the secondstage the rate of increase in cell numbers slackens and is replacedby cell extension, this stage being associated with a form ofmetabolism characterised by accumulation of carbohydrates andcell-wall constituents.The interdependence of carbon and nitrogen nutrition is shownby H. L. White 55 in Lemnu. When grown with insufficiency ofpotassium, the alga accumulates large proportions of starch anddry matter per unit leaf area, but the gross rate of carbonassimilation is restricted and amylolytic activity is low. Deficiencyof nitrogen also results in carbohydrate accumulation and lowamylolytic power, the former, under these conditions, being theresult of restricted multiplication (and therefore of sugar con-sumption) and diminished respiration.The metabolism of the colourless soil-inhabiting alga Prothecaxopfli is examined by H. A. Barker.s6 Complex organic forms ofnitrogen (e.g., yeast autolysate) are apparently essential for growth,63 Publ. Univ. California Biol. Sci., 1933, 1, No. 1, 1.53 Biochem. Z., 1936, 283, 364.54 Proc. Roy. Soc., 1936, B, 121, 451.66 J . Cell. C m p . Phy.&ol., 1936, 7, 73; 1936, 8, 231,66 Ann. Bot., 1936, 60, 403452 BIOCHEMISTRY.although some ammoniacal nitrogen is also assimilated. Hexoses,certain alcohols, and fatty acids but not hydroxy-, keto-, or dibasicacids, are utilised. Under aerobic conditions glucose is convertedinto cellular matter, largely glycogen, and carbon dioxide, but inanaerobic cultures the principal product is lactic acid. 50-80~0of the carbon entering the alga is assimilated.Nitrogen fixation by the blue-green alga Nostoc rnuscorum isshown by F. E. Allison, S. R. Hoover, and H. J. Morris 57 to bemuch more intensive than that by other species of this group.Both nitrogen and carbon can be obtained from the atmosphere,and growth and nitrogen fixation proceed normally in solutions ofmineral salts. Addition of sugars to the substrate, however,markedly increases the rate of growth. Moreover, the simplerforms of combined nitrogen (nitrate, ammonia, asparagine) areoften utilised more readily than is atmospheric nitrogen. Innitrogen- free media in darkness chlorophyll is produced andgrowth and fixation of nitrogen proceed slowly, 10-12 mg. ofnitrogen being fixed per g. of glucose consumed. I n unaeratedcultures carbon may be obtained from carbonates, although thealkalinity developing in the medium may ultimately kill the cells.The nitrogen-fixation process requires the presence of calcium,although growth of the alga proceeds with no more than a trace ofthis element. The beneficial effect of humus materials on thedevelopment of the organism is ascribed to its iron content andsuggests that the mechanism of nitrogen fixation resembles thatoccurring in Axotobacter.S. Endo 58 presents evidence that glucose is the first product ofphotosynthesis in the green alga Codium Zatum, a starch-producingorganism, whereas in Chadophora Wrightiana, which contains nostarch, fructose is the first detectable sugar. The influence oforganic substances on the respiratory activities of various algae isto some extent affected by their type and molecular complexity.A. Watanabe 59 records that increased respiration in ChZoreZZaellipsoidea follows the addition to the substrate of aldehydes,polyhydric alcohols, carbohydrates, amino-acids, and somecarboxylic acids (not aliphatic). Green, brown, and red marinealga are not, in general, affected by aldehydes, alcohols, orcarbohydrates. With ChZoreZZa and the green and brown alg= thechangg in respiratory rate effected by fatty acids varies with themolecular weight and is maximal with acids containing 8-10 C.iso-Acids are less active than n-acids in this respect. Moreover,5 7 Bot. Cfax., 1937, 98, 433.8 8 Sci. Rept. Tokyo Bunrika Dnigaku, 1936, 2, 223, 291.59 Acta Phytochim., 1937, 9, 235POLLARD : PLANT. 453although unsaturated fatty acids and keto-irioiiocarboxylic acidsincrease respiration in green and brown algze, di- and tri-carboxylicacids have little or no action.Constituents of Alga?.-J. Fischer, in examining thc carotenoidpigments of certain fresh-water algae, observes that in species ofchlorophyll containing EugZena, p-carotene, zeaxanthin, lutein (asesters), and xanthophyll are commonly found. E. heliorzcbesceszsalso yields esters of euglenarhodone,60 C40H48Q4. TrentepohZia spp.also contain tc- and p-carotene (from which the alga produces smallamounts of ionone), xanthophyll, lutein, zeazanthin, and a pigmentresembling fucoxanthin.61A new sterol, pelvestrol, is isolated from Higika fusiformis byK. Shirahama,62 who also establishes the presence of fucosterol inseveral other species.Cell-wall materials in Halicystis spp. are described by G. vanIterson, j ~ n . , ~ ~ as exhibiting the properties of amyloid matter andcallose. find that X-rayexamination of the cellulose of the cell wall of Valonia ventricosaindicates that the chains of cellulose units in alternate layers fallalong meridians and along spirals terminating a t the poles. Thedirections of the chains in the alternate layers lie a t an angle ofapproximately 83" and correspond with the striations of the cellPucoidin obtained from Laminaria digitata is established byG. Lunde, E. Keen, and E. oy 65 as a carbohydrate sulphuric esterof the type RO*SO,*OR' in which R comprises 60% of fucose andR' is principally sodium with smaller amounts of potassium,ca,lcium, or magnesium.I n red, brown, and green marine algs, flavin is very generallydistributed, Irideea spp. containing notably large amounts(> 1 x I n red and brown species,from 50% upwards of the flavin present apparently occurs as aflavoprotein . 66R. D. Preston and W. T. AstburyW ~ U S .g. per g. of dry matter).A. G. POLLARD.60 2. physiol. Chem., 1936, 239, 257.62 J . Agric. Chem. Soc. Japan, 1935, 11, 980; 1936, 1% 681.63 Proc. K . A k d . Wetensch. Amsterdam, 1936, 39, 1060.64 Proc. Roy. SOC., 1937, B, 122, 76.85 2. physiol. Chem., 1937, 24'9, 189.66 A. Watanabe, Acta Phytochim., 1937, 9, 255.O1 ]bid., 1936, 243, 103

ISSN:0365-6217    

DOI:10.1039/AR9373400398

出版商:RSC    

年代:1937

数据来源: RSC

摘要:

ANALYTICAL CHEMISTRY.IN this year’s Report on Analytical Chemistry it has been decidedto include separate sections on spectrography and on silicate analysis,as it seemed that both subjects, although perhaps somewhat special-ised, were sufficiently interesting and important to justify a specialaccount of the recent advances made in them. With silicate analysissuch an account has, indeed, been long overdue. Other subjects,such as the use of the polarograph and the development of micro-chemical technique and apparatus, especially in Organic Chemistry,are also due for special consideration, but must be deferred to afuture Report. Except for a brief treatment of the subject ofstandardisation in volumetric analysis the rest of the present surveydeals only with qualitative analysis on the micro-scale.The past year has seen the publication of many important papersconnected with gravimetric and volumetric analysis, but their survey,and also a report on organic analysis prepared by Dr.R. W. West,must be omitted owingt80 the limitations of space.L. S. T.1. SPECTRUM ANALYSIS BY TIIE EMISSION SPECTRUEd (1933-1 937).IN this summary it is assumed that the reader is aware of the stateof the art of spectrum analysis as applied to chemistry five yearsago. Spectrum analysis was then already in regular use for theexamination of almost every kind of substance-metals and alloys,liquids, powders, ore8, soils, glasses, slags and other vitreous sub-stances, refractories, precipitates, and residues, and animal andvegetable tissues.At that time the determination of the metallic(and some non-metallic) constituents of a mixture or compoundcould in general be made by the spectrograph to within 10-15%of the constituent, whether the quantity present was large or small.Progress since then may be epitomised as the achievement of approxi-mately four times this accuracy. As a consequence there are manymore analyses to-day than there were five years ago of which it canbe said that the spectrographic is better than the chemical methodof analysis. This result has been reached by replacing visualobservation of the photographed spectrum by the photometry ofthe lines and by studying the best way t o produce the radiation(the arc, spark, or oxy-hydrogen flame).The methods tend to resolve themselves into a limited numbeTWYMAN : SPECTRUM ANALYSIS BY EMISSION SPECTRUM.466each of which is widely applicable ; and in this Report most attentionhas been given to methods which have become of establishedutility in analysis. Those interested in the variety of applicationsshould refer to the Bibliography (p. 463). Although, doubtless, theRpectroscope continues to be used, almost all the new developmentsare concerned with the spectrograph.The quantitative accuracy here spoken of, is only attainable whenthe substance to be detected is present in a small amount. Whatthat amount should be naturally varies greatly with differentsubstances, but as a very rough rule one may place it a t approxi-mately 4%.Principles of Procedure which have become generally accepted-The results of many investigations have established that : (a) Anymixture or combination of elements can be made to emit aline spectrum characteristic of the elements; ( b ) in such spectrathe intensities of the lines of the various elements have a relationto each other depending only on the percentages present; (c)small variations in the percentage of any of the elements presentcause no variation in the intensities of the lines of the other elements.Quantitative spectrum analysis resolves itself, therefore, into ameasurement of the intensities of spectral lines.Since statements (a), ( b ) , and (c) are the foundations of quantita-tive spectrum analysis, it is desirable to consider briefly the limitswithin which they are true.Statement ( a ) requires no qualificationwhatever, except on the score of practical considerations, for as G. R.Harrison has recently pointed out, all the elements have sensitivelines, i e . , lines which are in evidence when only minute quantitiesare present. The metals and a few of the non-metals have thesesensitive lines in the range of spectrum lying between 2,000 and10,000 A., which is accessible to the ordinary quartz spectrographworking in air. Sensitive lines of most of the non-metals, on theother hand, are of wave-lengths shorter than 1850 A., at which airbecomes almost completely opaque. This is why practical spectrumanalysis is confined to the metals, including antimony and bismuth,the metalloids arsenic, selenium, and tellurium, and the non-metalsboron, phosphorus, and silicon ; since, although very many vacuumspectrographs are in use for physical investigations, the cost of theirconstruction and the difficulties of vacuum technique preclude theiruse in analysis,The ratio of the intensitiesof two lines of a substance (whether emitted by the same element orby two different ones) may vary greatly according to the means ofexciting the radiation (arc or spark).One should, therefore, always1 Ilfetals and Alloys, Nov., 1936,Statement (b) requires qualification456 ANALYTICAL CHEMISTRY.keep these conditions constant (e.g., maintaining the same sparkingcircuit, current, and distance apart of the electrodes).Very little has been published on the effect of the factor (c), butthe effect is an important ~ n e .~ g ~ For this reason the best resultsare obtained by comparing the samples to be analysed with specimensof known and not very different composition.The methods which yield the best results all adopt a principlewhich largely avoids errors arising from variations in the arc orspark discharge, vix., that the measurement should be based on acomparison of selected spectral lines of a minor constituent withthose of the main constituent-a principle called by W. Gerlachthat of the ‘‘ internal standard.” Analysis based directly on thisprocedure has been widely used by him and other^,^ who havecompiled lists of pairs of lines of the main and minor constituentswhich are of equal intensities at stated percentages of the latter.Theory and observation alike support the recommendation ofW. Gerlach and E, Schweitzer to use for the measurements whereverpossible only lines whose intensities relative to each other do notvary with even widely varying conditions of the arc or spark; inthis method those authors confine themselves to the use of lines whoseintensities remain equal to each other under widely different con-ditions of excitation, for as Gerlach points out,6 such lines remainof equal intensity even when they are over- or under-exposed. Heuses these “ homologous line pairs,” as he calls them, as the basisof his system of analysis.* To do so is a severe restriction on thechoice of lines, and, working with the microphotometer, one can usealso line pairs of unequal intensity, though these should still beselected so that the ratio of their intensities does not alter withchanges in the conditions of excitation.Various workers recommend lines suitable for particular analyses,and reference to these can be found in Smith’s bibliography and otherbooks mentioned on p.463.Methods of Pducing the Radiation.-In the period under reviewmany variations of the three main ways (flame, arc, and spark)have been put forward to meet the special requirements of those whohave devised them. Only the most important of them will beF. Twyman and C. S. Hitehen, Proc. Roy. SOC., 1931, A, 133, 72.0. S. Duffendack,lnd. Eng. Chem. (Anal.), 1935, 7, 410.“ Foundations and Methods of Chemical Analysis by the EmissionSpectrum ” (Adam Hilger, Ltd.).D.35. Smith, J . Inst. Metals, 1934, 55, No. 2, 283; 1935, 56, No. 1, 257;E. H. S. van Someren, ibid., 1934, 55, No. 3, 265; M. Milbourn, ibid., 1934,55, No. 2, 275.6 op. cit., p. 67.* Valuable lists of homologous line pairs are given in Gerlach and Ried’sbook (see p. 463)TWYMAN : SPECTRUM ANALYSIS BY EMISSION SPECTRUM. 457mentioned here, some preference being given to those which have beenused by workers other than those introducing them.H. Lundegiirdh continues to use the method describedby him for the analysis of solution^.^ He sprays the liquid into anacetylene-air flame from an atomiser,8 and claims that this pro-cedure is superior in constancy to either arc or spark; he has usedit with success in combination with a microphotometer in soiland plant analysis, and in physiological and pathological in-vestigations.Although, in general, the spark and arc yield a moresensitive detection of many of the metals, Lundegiirdh’s methodusually suffices in this respect for those which are of the greatestinterest in such fields of work, and the accuracy attained (using amicrophotometer) is very satisfactory. LundegSirdh says that theerrors of determination never exceed 5-7 yo, and with the alkalis,calcium, and manganese are not more than P--2yo.* The method hasbeen adopted by others with satisfactory results, and R. L. Mitchellclaims an accuracy in determining the alkalis and alkaline earthsof & 47,’,’, which can be improved by replication of the spectro-grams.Determinations such as those of strontium in the presenceof large excess of calcium, which are scarcely feasible otherwise on aroutine scale, present no difficulties.H. Ramage lo continues to use his flame method in the examinationof biological material. He puts the material to be analysed in afolded filter-paper, and places this in an oxy-hydrogen flame. Themethod is simple, although it does not approach the quantitativeaccuracy of Lundegiirdh’s (probably because Ramage uses no photo-metric means of measuring line intensities). It has been used ina survey of the micro-constituent elements of biological material.11With easily oxidisable or low-melting-point metals andalloys it is sometimes exceptionally difficult to obtain an arc whichis steady in either position or character, and to remedy thisW.Gerlach introduced the interrupted arc, in which the electrodesare repeatedly brought into contact and separated ; they do not gethot enough to be oxidised, and one thus avoids the almost continuousbackground, due to the complex molecular spectra, which causesdifficulty in using the arc spectra of, e.g., aluminium.Flame.Arc.“Die Quantitative Spectralanalyse der Elemente,” Parts I and I1See Ann. Reports, 1934, 31, 288. J. 8oc. Chem. Ind., 1936, 55, 267.lo Nature, 1936, 137, 67; H. Ramage, J. H. Sheldon, and W. Sheldon,l1 D. A. Webb and W. R. Fearon, Sci. Proc. Roy. Dublin SOC., 1937, 21,* m7here accuracy is stated the Reporter means in every case the percentage(Gustav Fischer, Jena; 1929 and 1934).Proc. Roy.SOC., 1933, B, 113, 308.487, 505.of the total amoiint of constituent present458 ANALYTICAL c3HEMIsTRY.S. Judd Lewis has extended the use of his pellet methodla (inwhich an ash or other powder is compressed into a pellet and placedon the lower pole of a copper or silver arc) by synthesising a secondpellet (whose composition is thus known) so that its spectrumexactly matches that of the pellet to be analysed. This in itselfmay not be new, though Judd Lewis seems to have been the firstfully to realise how many difficulties and instrumental complexitieswere thus avoided,* but he has added to this a very useful principle.By chemical determination of the main ingredient in the specimento be analysed (e.g., a portion of a plant) and spectrographic deter-mination of the ratio of the minor ingredient to that of the main onein the ash, he is able at once to state the percentage of the minoringredient in the original substance.He calls this the “Ratioquantitative ” method. The principle can, of course, be used withother means of producing the radiation, and it was used withRamage’s flame arrangement by Webb and Bearon.ll No quantita-tive method of spectrum analysis of like accuracy requires less in theway of apparatus than this, and although synthesis is not feasiblein the routine analysis of metals and alloys, the principle can beused with advantage in laboratories dealing with a run of similaralloys.M. Milbourn l3 pointed out that enhanced sensitivity in the detec-tion of minute amounts of impurities in copper is attained byusing a globule of the sample (0-2-0-5 9.) as electrode in place of asolid rod.Suitable lines and their intensities are given for thedetection and determination of Bi, As, Pb, Fe, Ni, Ag, Sb, and Snby this method. S. Pina de Rubies and J. Doetsch,14 desiring todetect extremely minute percentages, effected a concentration of aspecimen placed in the arc by allowing it to melt there and evaporateoff the more volatile constituents. Finally, K. Cruse and H.Schubert,f6 in determining lead in blood, effect a concentration of thelead by electrolysis, a method which was used many years ago byDupr6 in detecting the presence of mercury in gun-cotton ; electro-lytic concentration has also been used by A.Schleicher and(Frl.) N. Kaiser.16Spark. It is with the spark that most progress has been made inquantitative analysis in the last five years, It does not appreciablyconsume the material, or overheat it, and most important of all, itis more constant than the arc both in position and in character.A few new modes of producing the spark may be mentioned.l2 “ Spectroscopy ” (Blackie & (20.).l4 2. anorg. Chem., 1934, 220, 199.l5 2. anal. Chem., 1936, 105, 241.* For example, quantitative analysis can be achieved without the use of18 LOC. cit., ref. ( 5 ) .16 Ibid., p. 393.any photometric measurement of the intensities of the linesTWYMAN : SPECTRW ANALYSIS BY EMISSION SPECTRUM. 459W.Gerlach,l7 analysing very small areas of non-metallic specimenssuch as thin sections of animal organs (liver, etc.), mounts the speci-mens on slides and produces a high-frequency (Tesla) dischargebetween a point and the selected portion of the specimen.K. Ruthardt 18 has analysed metallurgical specimens in this way.0. E’eussner l9 modified the usual spark oircuit, to make it more con-stant, by introducing & rotary interrupter and resonant circuit.W. Seith and E. Hofer 20 blew an air blast from twin jets on the gapof the ordinary spark to remove the outer layer of comparativelycold metallic vapour which absorbs the radiation of certain of thespectrum lines. 0. S. Duffendack, for the analysis of solutions,added to the Twyman and Hitchen sparking tube for liquids2an exhaust for drawing o f f the fine spray caused by the spark.Later, with F.K. Wiley and J. S. OwensY3 he used a Pyrex or silicatube.It does not appear that any of these special sparking devices areneeded for the ordinary run of work in chemical or metallurgicalanalyses, and it remains the general practioe to use the simpleoscillating spark, with condenser and self -induction coil.21Devices for Collecting the Radiation.-Most frequently one desiresthat the spectrum should truly represent the whole of the radiationfrom the arc or spark, and that the spectrum lines shall be of uniformintensity throughout their length. To enswe this, a convex lensof quartz i s used, preferably near the slit, to form a real image ofthe light source on or near the prism of the spectrograph.Thereappears no need in spectrum analysis to continue the use of the oncepopular sphero-cylindrical condenser.The radiation is not uniform from pole to pole of the arc or spark,some spectrum lines being short, and only originating quite cloaeto the pole, while others are continuous from pole to pole. Thespectrographer may sometimes derive useful information fromobserving these differences, and he then changes the position of hiscondenser lens so as to produce an image of the light source on theslit; e.g., V. M. Goldschmidt,22 in the analysis of rocks, minerals,etc., observes the spectrum in the layer immediately near the cathode,thereby attaining greater sensitiveness, especially when small quan-l7 “ Clinical and Pathological Applications of Spectrum Analysis ” (Adamla Mstallw., 1934, 13, 869.Is 2.tech. Phgsik, 1932,18, 573 ; Arch. Eisenhuttenw., 1933, 0, 551.21 “ The Practice of Spectrum Analysis,” F. Twyman and others, 6th edtn.,28 See L. W. Strock, “ Spectrum Analysis with the Carbon Arc CathodeHilger Ltd.).8. Elektrochern., 1934, 40, 313.p. 20 (Adam Hilger Ltd., 1935).Layer ” (Adam H,ilger Ltd., 1936)460 ANALYTICAL CHEMISTRY.tities of material are utilised for the analyses. This method, devisedby R. Mankopff and C1. Peters, was improved by L. W. Strock, 23who forms on a screen an enlarged image of the arc; that portionof the image whose spectrum is desired (i.e., the cathode layer)passing through a hole in the screen.A further condensing lensplaced near the slit serves to produce that uniform illumination whichis essential for photometric measurement of line intensities.R. Breckpot 24 (using a stepped sector and microphotometer)points out how the readings of the microphotometer can be falsifiedowing to the definition of the line falling off towards the ends whenthe long slit is employed, which is necessary in working with thesector, and for this kind of work it seems desirable to take care thatwhen such a sector is used only the central part of the spectrographlens system is utilised.Means of determining the Intensities of the Lines.-A very simplemeans of quantitative analysis, and one which has been verywidely u ~ e d , ~ * ~ ~ is provided by making lists of homologous pairs oflines, lines, namely, of minor and major constituents of a substancewhich at known percentages are of like intensity.When theminor constituent is present in only slight traces, most of the linesof the major constituent will be considerably over-exposed, butusually weaker lines will be found which can be utilised. There arecases, however, e.g., when magnesium is the major constituent, inwhich no suitable weak lines are to be found, particularly as it isdesirable, in order that comparison may be made accurately, thatthe lines to be compared should be very close together. Variousdevices have been employed to deal with such cases ; e.g., there maybe an impurity easy of determination by chemical means which pro-vides lines of a suitable low intensity, or a known quantity of stsubstance may be added to serve as an intermediate comparison.26When a synthetic mixture to match the sample can be prepared,a quantitative determination can be made without any photometricappliance, and the necessary instrumental equipment is reducedto a minimum. I n the routine analyses of metals and alloys sucha procedure is not feasible, and even where methods of synthesisare applicable, time can be saved in the chemical operations andincreased accuracy can be obtained if methods of photometry areavailable.A number of devices have been applied to this purpose,but only two, the logarithmic sector and the microphotometer, havebecome a t all widely used.The logarithmic secfor.This device, due to G. Sclieibe and A.23 op. cit.25 W. Gerlach and $1. Riedl, op. c i f .s6 qT. Seith and A , Jieil, Z. E'lektrochem., 1936, 42, 299.24 Ann. Soc. sci. Bruxelles, 1937, 57, 129TWYMAN SPECTRUM SNALYSIS BY EMISSION SPECTRUM. 461Ne~haiisser,~~ is a disc whose periphery is cut to a logarithmic curve,and which is rotated in front of the slit, so that the exposure ismade to vary along the slit. This results in the lines on the spectro-gram being of different lengths, which are thus a measure of theirrelative intensities.The logarithmic sector has been used by a number of workers inthe last five years 28 with both the arc and the spark. To give oneexample only, M. Slavin 29 used it in determining cobalt, iron,copper, cadmium, thallium, germanium, and lead in concentratedzinc sulphate solutions, and iron, copper, cadmium, and lead inmetallic zinc.His procedure differs from that of P. Twyman andA. A. Pitch30 only in that he used salts packed into holes drilledin pure carbon electrodes instead of the solid metals ; he achieves anaccuracy within 10% for the majority of tests, with occasionalerrors amounting to 20%. The speed permits the method to be usedin the works control of such operations as involve the removal ofmetal below arbitrary concentration. Slavin uses the dried saltssince it is then easy to make mixtures of known composition,It appears that an accuracy of within 10% in determining a minorconstituent is usually obtained by the use of the logarithmic sector.The method is simple, but it is very difficult to define precisely theend-points of the lines.J. S. Poster and C. A. Horton 31 find thisdifficulty reduced by the use of a special optical comparator wherebythe two lines are brought adjacent to one another and moved untilthey taper off together. These authors also replace the sector bya graduated wedge film of aluminium.The microphotometer. This gives an accuracy distinctly greaterthan that of the logarithmic sector, and by using the microphoto-meters of the non-recording type which have been designed for thiskind of work, routine analyses can be carried out very quickly.Among those who have published results obtained with this methodare H.Lundegiirdh (solutions and acetylene flame),' 0. Findeisen(lead alloys),32 0. S. Duffendack et al. (solutions used with the ~ p a r k ) , ~R. Breckpot (general analyses using the stepped sector) 24 and H. K.Whalley (aluminium alloys with the spark) .33I n confirmation of the superiority of the microphotometer to themethods of wedge or stepped spectra (logarithmic sector, etc.) onemay instance the work of J. Cholak 34 on the quantitative spectro-2 7 2. angew. Chem., 1928, 41, 1218; see also ref. (21).28 For references, see Smith, Zoc. cit., ref. (5).29 Eng. Min. J . , 1933, 134, 509.31 Proc. Roy. SOC., 1937, B, 123, 422.33 2. Metallk., 1933, 25, 12.33 J . SOC. Chem. Ind., 1937, 56, 1 8 0 ~ .34 J . Amer. Chem. Soc., 1935, 5'9, 104; Ind.Eng. Chern. (Anal.), 1935, '7, 287.30 J . Iron Steel Inst., 1930, 122, 289462 ANALYTICAL CKEMISTRY.graphic determination of lead in biological material. In his earlierwork, he used a rotating logarithmic sector, later he preferredmicrophotometer measurements.The microphotometer is a thermoelectric or photoelectric instru-ment with which the density of blackening of the lines on a spectro-gram can be measured. It was first used in astrophysical investi-gations, and the problem of deriving from such measurementsthe relative intensities of the radiations themselves was solved byphysicists by sound but laborious methods.An instrument with which measurements of blackening of theplate can be made 10 times as accurately as by eye could not longescape the notice of spectrographers, and five years ago it was alreadybeing applied by them.Some of the claims to very high accuracythen made were scarcely justified, for the authors had neglected tomake use af the experience of the physicists; but in 1933, 0. S.DuKendack was (in exceptionally favourable cases) achieving a1 yo accuracy in the analysis of solutions. The work is now develop-ing into a widely applicable routine which, while sound, is also simpleand quick when applied to routine analyses.The astrophysicists who used the microphotometer for measuringthe intensities of spectral lines found it necessary to calibrate eachspectrum plate by imposing upon it a set of exposures of thesame light source but of differing and known relative intensities,thus producing stepped spectra.This principle was adopted byDuffenda~k,~ for example, with excellent re~ults.~5 It may benecessary wherever it is important to push the method to its highestachievable accuracy (although the Reporter doubts it), but it isvery laborious and may be avoided by the procedure describedbelow.The following procedure adopted in the Reporter’s laboratory,in which he thinks an accuracy of 2-5y0 is attained in the routineestimation of minor constituents of metals and alloys by theirspark spectra, is the result of endeavours extending over someyears to reduce the methods of other workers to their simplestterms consistent with reliability. A number of standard specimensare prepared or collected, the composition of which is like that of thesamples to be tested, but in which the proportions of the variousconstituents vary over the permitted range.Spectrograms of thewhole range of specimens are taken on the one pZate. The plate isput on the microphotometer, and galvanometer deflections areobtained with selected pairs of lines, one of the main and one of36 See also D. H. Follett, J. Sci. Instr., 1936,13, 221 ; J. S. Foster and D. R.Foster and Horton, however, McRae, Proc. Roy. SOC., 1936, A , 163, 141.reverted to a wedge method, see ref. (31)TWYMBN : SPECTRUM ANALYSIS BY EMISSION SPECTRUM. 463each minor constituent. A graph is then plotted for each minorconstituent with logarithms of the ratios of the galvanometerdeflections as abscissae and logarithms of the ratios of the per-centages of the minor to those of the main constituent as ordinates.In analysis, spectrograms of the samples to be analysed are takenin the same way.Any desired number can be taken on the plate,but there must also be included spectrograms of at least two of thestandard specimens. Microphotometric measurement of the spectro-grams of the standard specimens and comparison of the results withthe graph serve to check that the graph is applicable to the conditions*obtaining a t the time, and if so, the percentages of the variousconstituents can be immediately read off from the graphs. If not,provided the discrepancy be not great, it is only necessary tomultiply the percentages obtained from the graphs by a factoreasily derived from the measurements on the spectra of the standards.Development along these lines seems likely to become the acceptedprocedure for quantitative spectrum analysis.Direct Photometry of the Lines.-A few workers have used directphotoelectric comparison of the intensities of the lines without theintermediary step of taking a photograph, and doubtless where onekind of determination has to be made very frequently such anarrangement may be quick and accurate.There are few labora-tories, however, where so specialised a method would be worthwhile.36Bibliography and TubZes.-A number of books and tables have beenpublished in the last five years, of which the following are perhapsthe most useful :W. and We. Gerlach, “ Clinical and Pathological Applications ofSpectrum Analysis ” ; translated by Joyce Hilger Twyman (AdamHilger, Ltd., 1934) : Describes methods applicable to the examin-ation of biological samples and their applications to the detection ofspecial elements in organs, secretions, etc., with notes on applicationsin mineralogy and other special chemical problems. Contains verymany valuable notes : e.g., reference to coincidence lines, vix.,lines of different elements which may be confused one with another.W. Gerlach and E. Riedl, “ Die Chemische Emissionspektral-analyse,” Part I11 (Leopold Voss, 1936) : Very valuable tables ofthe most useful lines of a number of metals, each table includinglists of coincidence lines and of homologous line-pairs.Adam Hilger, Ltd., “The Practice of Spectrum Analysis,” 6th36 W.H. Jansen, J. Heyes, and C. Richter, 2. physilcal. Chem., 1935, 174,* Such as kind of plate, temperature and kind of development, condition291.of electrodes, exposure, etc464 ANALYTICAL CHEMISTRY.edtn. (1935) : A condensed but comprehensive review of themethods of spectrum analysis.fifitroductory Books.-S. Judd Lewis, “ Spectroscopy in Scienceand Industry ” (Black & Son, 1933) : An adequate introduction tothe methods, including those of absorption spectrography.P. Swings, ‘( La Spectroscopie Appliquke ” (George ‘Shone, 1935).Finally may be mentioned the indispensable classified “ Biblio-graphy of Literature on Spectrum Analysis,” by D. M. Smith(British Non-Ferrous Metals Research Association, 1935).This isconcerned mostly with metallurgical applications, but includesalso references to the most valuable general reviews of the subject.F. T.2 . THE ANALYSIS OF ROCKS ANY MINERALS.Since the publication of the last editions of W. F. Hillebrand’sand H. S. Washington’s classic treatises on rock analysis, a con-siderable amount of work has been done in this field, but most of ithas consisted either of a critical examination of existing standardmethods, or the adaptation of previously-known ones to the specialproblems involved in rock analysis. During recent years, in-creasing importance has been attached to the distribution of theless common elements in rocks and minerals on account of theirgeochemical significance.E. Troger has discussed this questionwith reference to the igneous rocks, and stressed the desirabilityof the determination of the minor constitueflts in rock analyseswhenever possible. Owing to the very small proportions in whichthese elements occur in the majority of rocks, the ordinary chemicalmethods are frequently inapplicable, and have been largely replacedby spectroscopic processes. H. Moritz 4 has enumerated the mostsuitable lines for use in the spectroscopic detection and determinationof the various elements in ores and rock-forming minerals, but theprincipal worker in this field has been V. M. Goldschmidt. Heand his co-workers have developed a special technique in theapplication of quantitative spectroscopy to the determination oft’he proportions in which the rarer elements, such as gallium,“ The Analysis of Silicate and Carbonate Rocks,” Washington, 1919.Most of the subject-matter of this monograph has been incorporated inHillebrand and Lundell’s book, “ Applied Inorganic Analysis,” New York,1929.“The Chemical Analysis of Rocks,” New York, 1930.Other worksdealing with this subject are : “ Anleitung zur chemischen Gesteinsanalyse,”by J. Jakob, Berlin, 1928 ; “ Gesteinsanalytisches Praktikum,” by E. Dit,tler,Berlin, 1933 ; “ Silicate Analysis,” by A. W. Groves, London, 1937.Chiem. Erde, 1934, 9, 286. Ibid., 1933, 8, 321BARWOOD : ANALYSIS OF ROCKS AND MINERALS. 465germanium, the platinum metals, etc., occur in the rocks andminerals constituting the crust of the earth.5The distribution of a large number of elements has been investig-ated by them, with surprising results in many cases, such as theunsuspected presence of germanium to the extent of 1% in the ashof certain coals.The spectroscopic methods in general affordquantitative figures for percentages of the element under investig-ation ranging from 0.01 to 0*0001 yo, and thus begin where ordinarychemical methods leave off.The tendency of modern petrological research to attach greaterimportance to the chemical composition of the individual mineralspresent in the rocks rather than to the figures obtained from thebulk analysis of the rock as a whole, has led to the demand for achange in analytical technique. Although the amount of materialavailable for the analysis of a rock is usually ample, the case isdifferent where the constituent minerals are concerned.Thesemay in certain cases form only a small fraction of the whole rock,and their isolation in a pure state is often a difficult and laborioustask, so that the analyst is ultimately faced with the problem ofcarrying out a complete analysis, involving the determination ofpossibly 13 or 14 constituents, on 1 g. of material or even less.In order to cope with demands of this kind, attempts have beenmade during the past few years to adapt the existing methods ofrock analysis so as to permit of the work being carried out on asemi-micro scale.A detailed account of the modified procedure employed in suchcases is given by W.C. Guthrie and (Miss) C. C. Miller,6 who haveused it in the analysis of several igneous rocks. Samples weighing0.1 g. were taken for the various determinations, a total of about0.7 g. being required for the whole analysis. Two analyses, eachcomprising 13 constituents, could be completed in four days, andthe figures obtained were in excellent agreement with those affordedby check analyses carried out by the usual methods. Work onsimilar semi-micro lines has also been carried out by W. Janczak,'who employed it for the analysis of dolomite and chemical glass.A start has also been made with the application of purely micro-chemical methods to the analysis of minerals and rocks. Oneof the earliest analyses of this kind was made by A. Benedetti-Pichler and H.Thurnwald,s who analysed kolbeckite, a mineral6 See numerous papers in the Nach. Qes. Wiss. GGttingen, and SET. NorskeVidenskaps-Akad., Matemat.-Naturv. Klasse, €or 1930-1935, and summaryin J., 1937, 655, where a bibliography will be found.6 Min. Mag., 1933, 23, 405. Rocz. Chem., 1935,15, 304; 1936,16, 377.8 Mikrochem., 1932,11,200; see also A. Benedetti-Pichler and F. Schneider,ibid., 1930, Emich Festschrift, 1466 ANALYTICAL CHEMISTRY.containing beryllium silicate and phosphate, in addition to iron,aluminium, calcium, and magnesium. Analyses of a number ofgarnets, isolated from various rocks, have been made on a micro-chemical basis by H. Hueber,g 30 mg. of the mineral being requiredin each case.*The chief worker in this field is, however, F.Hecht, who hascarried out much excellent and painstaking pioneer work, includingmicrochemical analyses of several radioactive minerals, such aspitchblende, thorianite, and monazite, using 20-50 mg. of material.1°The same worker subsequently extended similar methods to silicaterocks, and has analysed a glassy material separated from transfusedquartz.ll In a later paper,12 Hecht instances the advantages ofemploying microchemical methods of precipitation, filtration, etc.,in the determination of the minor constituents, such as manganeseand nickel, in rocks, and describes the procedures with full experi-mental details. Two analyses of basalts are given in illustration,in which the minor constituents have been determined in this way.More recently still, a complete scheme for micro-silicate analysishas been published by the same author.13 The methods givenpermit of the determination of the 16 principal constituents ofsilicate rocks, a total of eight portions of rock powder, varyingin weight from 10 to 20 mg.each, being required for the wholeanalysis. The procedure followed differs from that employed onthe macro-scale in several respects, notably in that silica is deter-mined in one separate portion of rock powder, whilst in a secondportion alumina, titania, total iron, lime, magnesia, and manganeseoxide are determined; in the latter case, the old unsatisfactorymethod of precipitating the manganese as sulphide and igniting tooxide is retained. Five analyses carried out by the above methodare cited in the paper.Tech.Min. Petr. Mitt., 1932, 43, 84.10 Mikrochem., 1931, 10, 46; 1932, 12, 193; F. Hecht and W. Reich-Rohrwig, ibid., p. 281; F. Hecht, Amer. J . Sci., 1934, 27, 321; F. Hecht andE. Kroupa, 2. anal. Chem., 1935,102,81; 1936,108,82; in this last paper thePb/U ratio is computed from the analyticaI data, and applied to the calculationof the geological age of the minerals.11 See A. Holmes and H. F. Harwood, " Petrology of the Volcanic Area ofBufumbiro, Uganda Geological Survey Memoir, 1937, 3, Part 2, 254, wherethese analyses are given.la 2. anal. Chem., 1937,110, 385.l3 F. Hecht, Mikrochim. Acta, 1937, 2, 188. * See also H. Alber and C . Benedicks, Arkiv Kemi, Min. Qeol., 1933, 11A,nr. 6 ; R. Treje and H.Alber, Jernk. Ann., 1933, 117, 457 ; M. Shioiri and T.Nagahara, J . Imp. Agric. Exp. Sta., 1933, 2, 161 ; M. Shioiri and S. Kane-matu, J . Japanese Ass. Min. Petr. Econ. Beol., 1934,12, 180; J. Iwasaki, ibid.,1935,13, 93HARWOOD ANALYSIS OF ROCKS BND MINERALS. 467The results obtained by Hecht in his analyses of minerals and rockson a purely microchemical basis are tolerably satisfactory, but inthose cases where a comparison analysis on the macro-scale wascarried out at the same time divergencies are often noticeable, thevalues obtained microchemically for lime and magnesia in par-ticular being frequently erratic. Experiments made with an“ artificial pitchblende,” synthesised from standardised solutions,14showed similar discrepancies, and it is quite evident that the micro-chemical analysis of complex minerals md rocks in which a largenumber of separations are involved cannot yet yield results corn-parable in accuracy with those obtained by ordinary macro-methods.The present tendency to extol microanalysis in all cases at theexpense of the mecro-methods, is, in the Reporter’s opinion, entirelyunjustifiable. A number of micro-methods, especially those in-volving organic compounds, such as the micro-Kjeldahl determin-ation, are superior to the corresponding macro-methods, in that fheyeffect a great saving of time and material without any sacrifice ofaccuracy.In mineral analysis, however, the case is entirelydifferent. Here, a number of determinations have to be madesuccessively on a single weighed portion of material, involving a,series of complex separations, whilst the constituents to be de-termined are usually present in widely differing amounts.Muchstress is frequently laid upon the saving of time effected by micro-methods in comparison with macro-ones. In a recent paperdealing with the appliances and methods used for the analysis ofminerals on a rni~ro-scale,~~ Hecht rightly gives a warning againstthe very real danger that any attempt unduly to shorten the timerequired for a microchemical analysis must inevitably result in aloss of accuracy. The saving of time is, moreover, often largelyillusory when all the relevant factors are taken into account.Weighings on a micro-balance consume much more time than thosemade on an ordinary chemical balance (especially on a modernaperiodic type), and micro-analytical work requires close attentionthroughout, so that it is not easy to keep a number of analyses inprogress simultaneously, as can readily be done on the macro-scale.The oarrying out of microchemical analyses also demands ahighly specialised technique and excellent working conditions, thelatter not always readily to be attained. At the present time it isimpossible t o carry out successfully all types of mineral and rockanalyses on a micro-scale, since, as Hecht states, the necessaryconditions for the separations have in many cases not yet beenworked out. Furthermore, when coarse-grained porphyritic rocks14 F. Hecht and H. KrafYt-Ebing, Mikrochem., 1934, 15; 39.15 Osterr.Chem. Z$., 1937, nr. 10, 1468 ANALYTICAL CHEMISTRY.are being investigated, composed of minerals differing widely infriability and hardness, and especially when micaceous mineralsare present, it seems doubtful if a sample weighing only 30 mg.or so would be truly representative.16In view of the above facts, it is the Reporter’s opinion that rnicro-analytical methods should be employed for rocks and mineralsonly in those cases where the small amount of material availablerenders their use imperative, for otherwise any saving of timeand materials effected is more than offset by the diminished accura,cyof the results.l7On the other hand, serni-micro methods do not suffer to such amarked extent from the disadvantages inseparable from puremicro-methods. They can be made to embody the best points ofboth the micro- and the macro-procedure, and offer a fruitful fieldfor development in their application to this branch of analysis.Recent work in connection with the macro-analysis of silicaterocks and minerals will now be discussed under the headings of theindividual determinations.8ampEing.-The variations shown in the figures obtained insuccessive analyses made from the same rock mass, and due todifferences in sampling, are discussed by F.F. Grout,18 who con-cludes from numerous analyses that, although for fine-grained rocksa single hand specimen is sufficient to provide a representative samplefor analysis, yet a different procedure is necessary for coarse-grainedrocks.It is recommended that the latter should be sampled bytaking a large number of chips at random from a fresh outcrop, upto a total of 60 lbs. or more in weight. The material thus obtainedis then crushed and quartered in order to obtain the final samplefor analysis. SuScient consideration is often not given to thispoint, and much subsequent careful analytical work may therebybe invalidated.Silica.-In connection with the determination of silica in silicates,W. F. Hillebrand and G. E. F. Lundell l9 point out that the thirdl6 See, however, J. Mika (2. anal. Chevb., 1928, 73, 257) and B. Baule andA. Benedetti-Pichler (ibid., 74, 442), who deduce mathematicalIy from thetheory of probability that a 5 mg. sample should be fully representative,This requires a particle size of 0-001 mm., and the effects of such fine grindingon the oxidation of the ferrous compounds and sulphides present in the rockcannot be ignored.l7 F.Hecht, in a private communication to the Reporter, has endorsedthe above, stating that in his opinion it is not possible t o carry out a complexrock analysis by purely micro-methods with the same degree of accuracy as isattainable on the macro-scale.la Amner. J . Sci., 1932, [v], 24, 394.l o “ Applied Inorganic Analysis,” 1929, pp. 540, 722HARWOOD : ANALYSIS OF ROCKS AND MINERALS. 469evaporation formerly recommended is unnecessary, as equilibriumis reached after two treatments, and a third evaporation yieldsno more silica, the small amount still remaining in solution havingto be recovered subsequently from the R20, precipitate.Nonumerical data are furnished, however, in support of this contention,which is not in accordance with the Reporter's own experience.The inconvenience resulting in some cases from the presence oflarge amounts of sodium salts in the solution obtained after thefusion of the rock with an excess of sodium carbonate as usuallyprescribed, is overcome by a method put forward by A. N. Finn andJ. F. KlekotkaY2O in which 0-5 g. of the silicate is intimately mixedwith only 0.6 g. of sodium carbonate, and the whole heated in aplatinum crucible in an electric muffle furnace for two hours at875". The mass is then digested with a little water, acid is added,and the analysis finished as usual.Two new papers dealing with the determination of silica in thepresence of fluorine have appeared, by J.I. Hoffman and G. E. F.Lundell 21 and W. T. Schrenk and W. H. Ode 22 respectively. Thefirst deals with an improvement of the old Berzelius method, zincnitrate being substituted for ammonium carbonate in the removalof the main bulk of the silica; and in the second it is claimed thatfluorspar in the presence of silica can be completely decomposedwithout loss of silica if heated with perchloric and boric acids, all thefluorine being evolved as boron trifluoride. The residual silica maythen be determined as usual.A difference method, basedon the decomposition of the sample withhydrofluoric and sulphuric acids, followed by conversion of the sul-phates into orthophosphates, by ignition with sodium meta-phosphate, is described by G.T. Galfajan and W. M. T a r a j a ~ ~ . ~ ~The results are said t o be accurate to O*lyo, even in the presence of29% of alumina. The above method has been adapted for micro-chemical procedure by K. Sch~klitsch.~~" Free Silica."-The determination of the amount of " free silica "(quartz) present in a rock is of importance owing to its presumedbearing on the question of silicosis. The old Lunge and Millbergprocess gives unsatisfactory results, but for coal-measure rocks anaccuracy of 1% is claimed by A. S h a ~ , ~ ~ using a modification ofW. A. Selvig's process,26 and this is confirmed by L. R. D ~ n n . ~ 'A. Knopf 28 used hydrofluosilicic acid to attack the silicates of the2 1 Ibid., 1929, 3, 581.23 2.anal. Chem., 1933, 92, 417.25 Analyst, 1934, 59, 446.20 Bur. Stand. J . Res., 1930, 4, 809.22 I n d . Eng. Chern. (AnaZ.), 1929, 1, 201.24 Nikrochem., 1935, 18, 144.2 6 Carnegie Inst. Tech. Min. Met. Invest. Bull., 1928, No. 21.27 Analyst, 1935, 60, 36.28 U.S. Pziblic Health Reports, 1933, 48, 183470 AXALYTICAL CHEMISTRY.rock, but W. R. Line and P. W. Aradine 29 recommend the replace-ment of this by hydrofluoboric acid as having less action on thequartz present. They claim that an accuracy of approximately1% is attainable in the determination of the quartz. The errorcaused by the solubility of the quartz in hydrofluosilicic acid in-creasing with its fineness of division has also been pointed out byC.B. M ~ k e . ~ ~It has been shown 31 that micrometric estimations of the amountof quartz present in thin sections made from igneous rocks agreewithin 2% with the results obtained by chemical methods. Withsedimentary rocks the figures obtained are too low, and the methodcannot therefore be applied to shale or slate.A modified petrographic immersion method for free silica inrock powders or dusts has been described by H. L. Ross and F. W.Seh1,32 and a calorimetric method for the determination of ths“ active silica ” in puzzuolana has also been evolved.%A2umina.-The customary procedure hitherto baa been to takethe alumina by difference after determination of all the other oxidescomposing the “ ammonia precipitate.’’ A direct determinationof this constituent has now been rendered possible by the applic-ation of 8-hydroxyquinoline.Iron, titanium, and zirconium areremoved by an excess of sodium hydroxide, and the filtrate, contain-ing aluminium (and beryllium, if present) is acidified with hydro-chloric acid. The aluminium may then Be precipitated by theaddition of an acetic acid solution of 8-hydroxyquinoline, followedby the addition of 2N-ammonium acetate, the beryllium remainingin solution. By suitably modifying the conditions, a separationfrom phosphoric acid can also be attained.3* The above method hasbeen applied by Knowles 35 and by Knowles and J. C. Redmond 36to the determination of alumina in felspar. It has also beenutilised by C.0. Harvey3’ in the analysis of an apatite rock, andby P. P. Budnikov and S. S. Shukovskaja38 in that of bauxites,clays, and earthenware. The errors which result in this method iftitanium is not previously removed have also been pointedThe 8-hydroxyquinoline reagent has also been used by K. Schok-litsch40 for the precipitation of iron, aluminium, and magnesium29 Id. Eng. Chem. (Anal.), 1937, 9, 60..w A. Shaw, Bull. Inst. Min. Met., 1936, No. 385.Ind. Eng. Chem. (And.), 1935, 7 , 30.s3 P. P. Budnikov and L. G. Gulinova, Kolloid-Z., 1935, 70, 100.84 H. B. Knowles, J. Res. Nat. BUT. Stand., 1935, 15, 87.86 L O C . cit.37 Analyst, 1936, 61, 817.a9 P. Koch, Ber. deut. Iceram. Ges., 1935, 16, 118.40 MikTochem., 1936, 20, 247.30 J .I d . Hyg., 1936, 18, 299.a6 J . Arner. Ceramic Soc., 1936, 18, 106.88 J . Appl. Chem. Ru8sk, 1936, 9, 2079HARWOOD : ANALYSIS OF ROCKS AND MINERALS. 471in the micro-analysis of silicates. Contrary to the generallyaccepted view, 0. V. Krasnovski41 states that alumina can beaccurately determined by the usual methods (precipitation withammonia in presence of methyl-red as indicator) in aluminium-bearing borosilicates without previous removal of the boric oxide,even when as much as 30% of the latter is present. With more than10% of alumina, however, a double precipitation is necessary.The replacement of ammonia by pyridine * has been recommendedfor the precipitation of the R,O, oxides in the analysis of cobaltand manganese ores, but does not appear to have been tested yetfor rocks, although from a preliminary experiment carried out in theReporter's laboratory the method seems promising.Ferrous and Ferric OxidM.-In the determination of ferrous oxidein rocks, V.Smirnov and N. Aidinjan43 decompose the samplewith hydrofluoric and sulphuric acids under a layer of toluene.The resulting solution is poured into water, and the determinationcompleted as usual.In order to avoid any transference of the ferrous iron solution,as is inevitable in the usual methods of procedure, B. A. Soule44effects decomposition of the sample in a Pyrex flask with hydro-fluoric and sulphuric acids ; the titration is made electrornetricallyin the same vessel with ceric sulphate solution. In these circum-stances reducing substances (arsenious oxide) dissolved from theglass are without influence, which is not the case if permanganateis used.A number of rock-forming minerals such as tourmaline,ilmenite, and some varieties of garnet are very imperfectly decom-posed by hydrofluoric acid; in such cases Pratt's method giveslow results for the ferrous oxide content, but a method worked outby H. P. Rowledge45 can be employed. The rock or mineral isfused at 950" in a Pyrex tube with sodium borofluoride, the melt dis-solved in sulphuric acid in absence of air, and the solution titratedwith permanganate. A. T. Tscherni 46 determines ferrous oxidein rocks and minerals containing manganese peroxide by heatingthe sample in carbon dioxide for one hour a t 100" with standardisedferrous sulphate solution in the presence of sulphuric and hydro-fluoric acids; the excess of ferrous salt is then titrated with per-manganate.In another sample the active oxygen present is de-termined by the usual method, and the ferrous oxide content canthen be calculated.2. anal. Chern., 1929, 79, 175.dz See Ann. Reports, 1936, 33, 442, ref. 88.43 Compt. Tend. Acad. Sci. U.R.S.S., 1937, 14, 353.44 J . Amer. Ghem. Soc., 1928, 50, 1691; 51, 2117.45 J . Roy. SOC. Western Australia, 1933-1934, 20, 165.46 Ukrain. Chern. J., 1936, 11, 15472 ANALYTICAL CHEMISTRY.In general, the amount of ferric oxide in a rock is obtained bydifference, after determinations have been made of the ferrous ironand total iron content.It may, however, be determined directlyby a method due to 0. Kackl.47 The solution obtained by dis-solving the rock in hydrofluoric and sulphuric acids is titrated withtitanous sulphate solution, after addition of boric acid to combinewith the excess of hydrofluoric acid. The results are always slightlytoo high, due to oxidation taking place during the decompositionof the sample, but the process is useful whenever organic matteris present (e.g., in bituminous shales) which would interfere withthe customary permanganate titration.Magnesium.-If manganese has not previously been removed, itwill be precipitated with the magnesium, and L. A. Dean and E.Truog 48 have shown that this precipitation is quantitative. Theseworkers precipitate the two metals together as phosphates, weighor titrate the precipitate, and then determine the manganese presentby the bismuthate method, the magnesium being found bydifference.*8-Hydroxyquinoline has been applied by several workers to thedetermination of magnesium in silicates.49 A point which does notappear to have been fully investigated in this connection is thebehaviour of any manganese, not previously removed, in the solu-tion a t the time the precipitation is made, and the necessity forintroducing a correction for its possible presence in the precipitate.According to K. Schoklit~ch,5~ who worked on a micro-scale, thewhole of the small amount of manganese present was precipitatedwith the magnesium complex, and could be determined colori-metrically after destruction of the oxine with nitric acid and hydro-gen peroxide.Only two results are quoted, however, and in eachcase the amount of manganese found was only half that given in acorresponding macro-analysis.Potassium and Sodium.-As the blank on the reagents used inLawrence Smith’s process comes almost entirely from the calcium47 2. anal. Ch,em., 1925, 66, 401.4 8 Ind. Eng. Chem. (Anal.), 1935, 7, 383.49 J. I. Hoffman and G. E. F. Lundell, Bur. Stand. J . Res., 1930, 5, 299;6o Milcrochem., 1936, 20, 247.* In the Reporter’s laboratory, it has been the practice for years to deter-mine the amount of manganese present in the magnesia precipitate after thishas been weighed, and correct the weight accordingly. It has been foundthat in general about two-thirds of the total manganese present is precipitatedwith the magnesia, and the balance with the R,03 oxides, onIy a negligibleamount accompanying the lime.This method has proved more satisfact’orythan separating the manganese as sulphide in the course of the analysis,J. Robitschek, J . Arner. Ceramic SOL, 1928, 11, 587, et alHARWOOD : ANALYSIS OF ROCKS AND MINERALS. 473carbonate, E. R. Caley 51 prefers to dissolve 2 g. of this in hydro-chloric acid, and to determine the sodium directly in the solutionwith magnesium uranyl acetate. Whether it is permissible toignore the amount of alkali introduced from the glass of the washbottles, etc., during the operations is a moot point, although thework of Miller and Traves (see below) seems to support the con-tention.No provision is made, however, for the possible presenceof potash, a small amount of which is generally obtained in a blankrun, according to the Reporter’s own experience.A modification of the Lawrence Smith method which permitsof the determination of the alkalis without previous removal of thecalcium has been worked out by (Miss) C. C. Miller and (Miss) F.Traves.52 The solution obtained by the usual procedure is made upto a known volume, and sodium is determined in an aliquot part bydouble precipitation with zinc uranyl acetate. In a second portion,potassium is determined as perchlorate after a preliminary separa-tion as cobaltinitrite. Lithium, if present, is determined by extrac-tion of the lithium chloride (and calcium chloride) with isoamylalcohol or acetone, and subsequent determination as lithium zincuranyl acetate under carefully controlled conditions.It wasfound by these workers that a direct determination of the sodiumcontent of the calcium carbonate used, made by a double precipit-ation with magnesium uranyl acetate, checked well with the amountactually obtained in a blank run.The well-known Berzelius method has been modified by E. W.Koenig,53 who removes aluminium, iron, and magnesium fromthe solution of the rock by the addition of lime, the remaining silicabeing simultaneously eliminated as silicofluoride . The excess ofcalcium is then removed with ammonium carbonate, and theanalysis finished as usual.Cmsium and Rubidium.-These two elements are present inappreciable quantities in many naturally occurring silicates, suchas beryl and zinnwaldite (see V.M. Goldschmidt 5), but have rarelybeen determined owing to the difficulties attending their separation.A procedure for the separation and determination of all the alkalimetals has now been worked out 54 which enables small quantitiesof rubidium and c*sium to be determined in minerals in additionto lithium, sodium, and potassium ; the principal reagents requiredare platinic chloride, alcohol, ether, and ammonium sulphate. Iflarge amounts of rubidium or cesium are present (as in pollucite)some modification of the original method is ne~essary.~5I n d . Eng. Chern. (Anal.), 1929, 1, 191.53 Ind. Eng.Chern. (Anal.), 1935, 7, 314.54 R. C. Wells and R. E. Stevens, ibid., 1934, 6, 439.66 J. C. Hillyer, ibid., 1937,9,236; R. C. Wells and R. E. Stevens, ibid, (reply).62 tJ., 1936, 1390474 ANALYTIUAL CHEMISTRY.Wader.-The usual methods for the determination of water insilicates give untrustworthy results in the case of many micas, andan improved procedure, which is a combination of Penfield's andthe sodium tungstate method, has been devised by K. Wiskont andI. Alimarin 56 for use in the analysis of micas. The fact that epidoteis one of the few minerals which do not give up the whole of theirwater when heated to 1000" in a current of dry air has been pointedout by A. F. S m e t h ~ r s t , ~ ~ who obtained only 0.35% of water inthis way from a specimen of the mineral, whereas fusion with sodiumtungstate gave 1.32%.It has been frequently confirmed in theReporter's laboratory also that; with many rocks fusion with sodiumtungstate yields a higher percentage of water.F. Hecht 58 determines water in minerals microchemicdly byignition in a current of dry air, using a modified Pregl combustionapparatus; sulphur dioxide and hydrochloric acid if present are re-moved by a layer of lead monoxide and dioxide. The determin-ation of water in rocks and minerals by micro-methods has also beencarried out by E. Dittler and H. H ~ e b e r . ~ ~Carbon Dioxide and Carbon.-The use of perchloric acid forliberating carbon dioxide in the analysis of carbonates has beenrecommended 6O and an apparatus for the purpose described.M.H. Hey has devised an apparatus in which the liberatedcarbon dioxide is absorbed in barium hydroxide solution, and theresulting barium carbonate filtered off and washed in the absenceof atmospheric air before being weighed. Although doubtlesssatisfactory, the method seems unnecessarily elaborate by corn-parison with the excellent and much simpler one in which G. T.Morgan advocated the use of phosphoric acid.62 A micro-methodfor the determination of carbon dioxide in minerals such as Icelandspar is given by E. Dittler and H. Hueber 63 : 3-5 mg. of the mineralare decomposed by hydrochloric acid, the oarbon dioxide evolvedis collected in barium hydroxide solution (containing a little bariumchloride to diminish the solubility of the barium carbonate formed),and the excess baryta is titrated with 0.01N-hydrochloric acid.An improved wet-combustion method for the determination oforganic carbon in rocks and minords has been worked Thisis based on Morgan's process, but an additional flask is used, con-taining chromic acid, phosphorio acid, and a, little mercuric oxide,to ensure completeness of the oxidation.Carbon dioxide and56 2. anal. Ckem., 1929, 79, 271.6 8 Mikrochim. Aca, 1937, 1, 194.59 2. anorg. Chem., 1931, 195, 41; 199, 17.6o C. A. Jackson and J. W. Haught, Ind. Eng. Chem. (Anal.), 1930, 2, 334.61 Min. Mag., 1935, 24, 76. 62 See Ann. Reports, 1936, 38, 447.c3 2. anorg. Chem., 1931, 199, 26. O4 B. E. Dixon, Analyst, 1934, 59, 739.6 7 Min. Mag., 1935, 24, 173HXRWOOD : ANALYSIS OF ROCKS AND MINERALS.475carbon are determined successively in the mme aample of material,and the method is especially well suited for the determination oforganic carbon in rocks which contain considerable amounts ofcarbon dioxide.Titanium Dioxide.-The colorimetric determination of titaniumby means of hydrogen peroxide has been studied in detail by H.Gin~berg,~~ who finds that as little as 0.07 mg. of titanium dioxidein 100 ml. of solution can be determined with an accuracy of 10%if a Pulfrich photometer is used. The well-known bleaching of theyellow pertitanate colour due to phosphate ion may be prevented,according to I?. G. GermuthYG6 by the addition of 1 ml. of 0.1%uranium acetate solution for each 0.1 mg.of titanium dioxidepresent.An extremely useful method for the gravimetric determinationof titanium 67 affords a direct separation from iron, aluminium,manganese, and phosphoric acid, and can consequently be applieddirectly to the R,03 precipitate. The latter is dissolved in sulphuricmid, and the titanium precipitated from the acid solution by theaddition of tannin and phenazone, an orange-red precipitate beingformed, which on ignition yields titanium dioxide. The Reporterhas obtained promising results with this method in the determinationof titanium in rocks when the amount present was too large for thecolorimetric method to be used.Phosphoric Oxide.-The well-known effect of titanium in hinder-ing the quantitative precipitation of phosphoric acid as ammoniumphosphomolybdate may be offset G8 by the addition of considerableammonium nitrate or chloride together with free acid, providedthat less than 35 mg.of titanium are present ; with more than thatamount, quantitative precipitation of the phosphorus cannot beattained. The complete analysis of a phosphate rock requiresmodification of the usual methods, and a scheme for use in such acase as exemplified by apatite rock is given with full practical detailsby C. 0. Har~ey.6~ The determination of phosphoric oxide by 8direct precipitation with magnesia mixture in the presence ofammonium citrate to prevent interference by iron and other metalshas been used successfully by J. I. Hoffman and G. E. F. Lundell 70in the analysis of phosphate rock, silicate cements, eto., and itsemployment in referee analyses of these materials is advocated.2irconia.-The selenite method for the determination ofa@ 2.anorg. Chsm., 1931,198, 162; 1932, 209, 106; 1933, 211, 401; 1935,66 J. AmeT. Chern. Soc., 1928, 50, 1910.6 7 L. Moser, K. Neumayer, and K. Winter, Monatsh., 1930, 55, 86.68 G. HergBrd, Z. anal. Chem., 1933, 9S, 329.69 Analyst, 1936, 61, 817.226, 57.7* J. Res. Nat. BUT. Stand., 1937, 19, 59476 ANALYTICAL CHEMISTRY.zirconium 7 1 has now been combined with the older phosphateprocess, and applied to 0res.72 A further modification consists inthe precipitation of the zirconium as arsenate, and conversion intozirconia by ignition, the arsenic in the precipitate being removedby ignition with carbon (filter-paper).73Hillebrand’s original method for the determination of zirconiumin rocks, which is somewhat tedious, has been modified by H. F.Harwood. 74Fluorine.-0. Hack1 75 uses a duplication method based onSteiger’s colorimetric process with titanium sulphate and hydrogenperoxide. R. E. Stevens 76 uses the Berzelius method of attack,and treats the solution containing sodium chloride and fluoridewith gelatin, alcohol, and calcium chloride. Calcium fluoride isformed as a protected colloid, and may be determined nephelo-metrically ; an accuracy of 1 yo on the fluorine is claimed. The fadingin colour produced by fluorine in solutions of iron acetylacetone isutilised by W. D. Armstrong 77 for the determination of this element ;differences due to variations in acidity are eliminated by a duplica-tion method.F. Specht 78 has applied the lead chlorofluoridemethod to the analysis of cryolite, and the determination of fluorinein glasses and enamels is the subject of a paper by J. I. Hoffmanand G. E. F. L~ndell,’~ who substitute zinc nitrate for ammoniumcarbonate in the removal of the silica,* and determine the fluorineas lead chlorofluoride. Fluorine may be determined in cryoliteby a volumetric method due to F. J. Frere,80 in which the titrationis effected with yttrium nitrate or cerous nitrate solution; the leadchlorofluoride method was found to give low results. A numberof volumetric and gravimetric methods for the determinationof fluorine in zinc ores are discussed by I,.P. Taylor.81The bleaching action of fluorine on the reddish-violet colourgiven by alizarinsulphonic acid with soluble zirconium salts hasbeen utilised by several workers. H. Leitmeier and F. Feigl 82and also I. P. Alimaring3 have applied the reaction to thedetection of small amounts of fluorine in minerals and rocks.7 1 S. G. Simpson and W. C. Schumb, J . Amer. Chem. A~OC., 1931, 53, 921.72 Idem, Ind. Eng. Chem. (Anal.), 1935, 7, 36.75 W. C. Schumb and E. J. Nolan, ibid., 1937, 9, 371.54 Tidsskr. Kjemi Berg., 1932, 12, 23. 75 2. anal. Chem., 1934, 97, 254.713 Ind. Eng. Chem. (Anal.), 1936, 8, 248. 7 7 Ibid., 1933, 5, 300.78 2. anorg. Chem., 1937, 231, 181.Ind. Eng. Chem. (Anal.), 1933, 5, 17.82 Tsch. Min. Petr.Mitt., 1929, 40, 6. * This method for the removal of silica has been adopted in the Reporter’slaboratory for use in the Berzelius method of determining fluorine, and foiindto be a decided improvement, efferting an appreciable saving of time.Bur. Stand. J . Res., 1929, 3, 581.81 I n d . Chem., 1937, 13, 221.83 2. anal. Chem., 1930, 81, 8HARWOOD : ANALYSIS OF ROCKS AND MINERALS. 477The last worker mixes the powdered rock with boric oxideand heats it in a hard-glass tube, as in Penfield’s method forwater. If fluorine is present, hydrofluoboric acid collects withthe water in the bulb, and the fluorine may then be detectedby the zirconium-alizarin reaction. It is claimed that O . O O S ~ Oof fluorine can thus be detected in 0.3 g. of rock.According toF. Feigl and E. Rajmann,84 the sensitivity of the above tests maybe greatly increased by the replacement of zirconium-alizarin byzirconium p-dimethylaminoazophenylarsonate : 0.25 pg. of fluorinecan then be detected. Attention has been directed 85 to the fact,that the volatilisation method for fluorine (as silicon tetrafluoride)yields untrustworthy results for slags and certain mineral phosphateswhich contain silicates decomposable by acid. The error is ascribedto the formation of a non-volatile compound of fluorine, probablySiOF, .Vanadium, Chromium, Molybdenwm-The methods employedfor the determination of vanadium in rocks are discussed by K.Jost,86 and the distribution of chromium in rocks has been studiedby both ordinary and X-ray spectroscopic methods by several~orkers.~7 An entirely new process for the determination of theabove three elements in rocks, based on colorimetric methods, hasbeen worked out by E.B. Sandell; 88 0.001% of chromium orvanadium, and O - O O O l ~ o of molybdenum can be determined in thesame 1-g. sample, which is decomposed by fusion with sodiumcarbonate. Vanadium is determined colorimetrically with phospho-tungstic acid in an aliquot part of the aqueous extract of the melt,after it has been previously separated from chromium by the ex-traction of its 8-hydroxyquinoline compound with chloroform.Chromium is determined with diphenylcarbazide after removal ofvanadium, and molybdenum by the stannous chloride-thiocyanate-ether process. The Reporter finds that the method gives quitesatisfactory resultls, and effects a considerable saving of time andmaterial over the older process of Hillebrand, which required 5 g.of rock.A new study of the colorimetric phosphotungstate methodfor vanadium, as used in the above process, has been made byE. R. Wright and M. G. Mel10n.~~Nickel.-A direct method for the determination of nickel oxide inrocks has been worked out by H. F. Harwood and L. S. Theobald.9084 Mikrochem., 1932, 12, 133.85 D. S. Reynolds and K. D. Jacob, Irtd. Eng. Chern. (Anal.), 1931, 3, 371.86 Chern. Erde, 1932, 7, 177.V. M. Goldschmidt and C1. Peters, Nach. Ges. Wiss. GBttingen, 1933, 278;G. voii Hevesy, A. Mesha, and K. Wiirstlin, 2. anorg. Chem., 1934, 219, 192,88 Ind.Eng. Chem. (AnaE.), 1936, 8, 336.89 Ibid., 1937, 9, 251. O0 Analyst, 1933, 58, 673478 ANALYTICAL OHEMISTRY.The rock is dissolved in hydrofiuoric and sulphuric itcid8, andthe nickel determined directly in the resulting solution by precipit-ation with dimethylglyoxime or a-furildioxime, citric acid beingadded to prevent the precipitation of the R,03 oxides; 0-0025~0of nickel oxide can thus be detected when working on 2 g. of rock.Tho same authors have investigated the behaviour of nickel in rockanalysis. In the ordinary course of analysis some nickel is pre-cipitated with the R,O, oxides, and when the total nickel exceedsO-OEi% a correction must be made for this. The whole of the re-mainder passes into the filtrate from the magnesia, and may bedetermined in this after the removal of ammonium salts.Ncmganese.-The addition of various oxidising agents to thesolution during the precipitation of the R,03 oxides by ammoniahag been studied by E.V. Holt and H. F. MarwoodYg1 who find thatthe addition of bromine water simultaneously with the ammoniaensures complete co-precipitation of the manganese, provided thatnot more than 60 mg. of manganous oxide be present. Potassiumpersulphate, or hydrogen peroxide, is not satisfactory, as it is thenimpossible to obtain the whole of the calcium in the atrate, evenwhen two precipitations are made. 0. HackIy92 however, appearsto have overlooked the latter point, and precipitates manganesetogether with the R,O, oxides by the addition of ammonia andhydrogen peroxide.The precipitate is dissolved in cold 50%nitric acid, and reprecipitated. The manganese in the ignitedprecipitate is determined calorimetrically after fusion with potasaiumand sodium pyrosdphates ; titanium and iron may be subsequentlydetermined in the same solution. Unfortunately no numericaldata are adduced in support of the completeness of the separationfrom the alkaline earths.Burium and 8trontium.-The inaccuracy of the usual method forthe determination of strontiuin in rocks has been pointed out by€I. IF. Harwood93 and by W. NolI.94 The principal source of errorlies in the incompleteness of the precipitation of strontium as oxalatealong with the caIcium, especially when two precipitations are made ;according to Noll, an error of 5% on the strontium may result fromthis cause. Most of this strontium can be recovered by the additionof a strontium-free calcium salt to the filtrate from the second pre-cipitate of calcium oxalate, and determination of the strontiumin the precipitate so obtained.The nitric acid method of W.No11 95 is preferable to the ether-alcohol process in the separationO1 Min. Mag., 1927, 21, 318.sa 2. anal. Chem., 2936, 105, 81, 182; 1937,110, 401.Og aeol. Mag., 1033, 78, 142.95 2. anorg. Chem., 1931,199, 193.B4 Chem. Erde, 1933-1934, 8, 507HARWOOD : ANALYSIS OF ROCKS AND MINERALS. 479of small amounts of strontium from Euch calcium. For thegreatest accuracy, however, a spectroscopic method is preferred to apurely chemical one where strontium is concerned, C.J, vanNieuwenberg and R. H. Dewald,96 on the other hand, have testedfive different rocks of various types for their strontium content, bothby chemical and by spectroscopic methods. The two sets of valuesagreed well; hence they conclude that the apparent anomaly in thegeochemical frequency of barium and strontium (which occur inrocks in approximately equal amounts, whereas in most othergroups of elements the geochemical frequency falls with increasingatomic weight) is not due to analytical under-estimation of thestrontium present.The errors in the usual chemical methods for the determinationof barium in rocks are discussed by W. von EngelhardtY97 and thesomewhat disturbing conclusion is reached that the results areuntrustworthy for small amounts of barium (less than O.lyo).Aspectroscopic method is advocated.Borofi.-Boron is rarely determined in ordinary analyses of rocks,but V. M. Goldschmidt and C1. Petersgs find that, although thiselement is usually present in igneous rocks only to a very minuteextent (O~oO05-0~OOl yo), yet a large number of determinationscarried out on sedimentary rocks (clay-slates) showed that thesehad an average content of 0.1% of boric oxide. Whenever rocksof this class are being analysed, a determination of boric oxide isconsequently clearly desirable.Rare Earths.-A new method for the determination of thoria inmonazite sand, based on the separation of this oxide from the ceriumearths by means of hexamethylenetetramine, is given by A.M.Ismail and H. F. H a r ~ o o d . ~ ~ The existing method of W. F. Hille-brand for the determination of rare earths in silicate rocks is longand tedious; a shorter process is much to be desired, but has sofar not appeared.Copper, Lead, Zinc.-The colorimetric method for copper withsodium diethyldithiocarbamate has been applied by A. W. Grovesto the determination of copper in rocks ; 0.001 yo of copper can bedetermined in a 2-g. sample of rock. A procedure €or the de-termination of copper, lead, and zinc in silicate rocks, based onFischer’s use of dithizone for the detection of traces of the heavymetals, has been worked out by E. B. Sandell : O.OOOZ~o of leador copper and o.oo3~0 of zinc can thus be detected. The limit96 Rec.Trav. chim., 1935, 54, 633.g 8 Nach. Qes. Wiss. QGttingen, 1932, 402.O9 Analyst, 1937, 62, 185.Ind. Eng. Chem. (Anal.), 1937, 9, 464.97 Chem. Erde, 1935-1936, 10, 187.Min. Mag., 1935, $4, 35480 ANALYTICAL CHEMISTRY.of accuracy of the determination is about 20% when working on0.25 g. of rock powder.Beryllium.-The detection and determination of beryllium inrocks has been discussed by G. Reinii~ker,~ who states that anapproximate idea of the beryllium content of a rock may be obtainedby means of Fischer's quinalizarin reaction, the solution beingdiluted until the limit of sensitivity is reached; 3-5 pg. give apositive, and 2 pg. a negative, reaction. A direct colour comparisonis not possible with this process. One of the main difficulties in thedetermination of beryllium in rocks has hitherto lain in the separationof the small amount of beryllium from the titanium present.Thishas now been overcome by B. E. D i ~ o n , ~ who precipitates thetitanium with p-chloroaniline, the beryllium being subsequentlyprecipitated by ammonia.H. F. H.3. INORGANIC ANALYSIS.S'tandards for Volumetric Analysis.This subject has been dealt with in the last two Reports1 anddeserves to be mentioned once again. G. F. Smith and G. F. Croadhave been unable t o confirm the work of Waldbauer et a.L3 concerningthe stability of anhydrous sodium carbonate at temperatures up to450"; they have shown that at temperatures above 300" there isappreciable decomposition, and the resulting product is unsuitableas an acidimetric standard.This, of course, is in harmony with thegenerally accepted procedure, but the lack of agreement overpoints such as this seems to be typical of the whole subject ofstandardisation.The use of borax as an acidimetric standard was highly recom-mended in 1926: but chemists have been reluctant to change fromthe sodium carbonate method in spite of many objections that canbe raised against it. Now that the findings of H. Menzel5 thatborax can be kept indefinitely over a solution saturated with respectto sucrose and sodium chloride have been confirmed,6 it seems thatthe last objection to the use of borax has been removed. This,and the superiority over the carbonate in other respects, makethe change-over eminently desirable.3 2.anat. Chem., 1932, 88, 29. Analyst, 1929, 54, 268.Ann. Reports, 1935, 32, 452; 1936, 33, 433.I n d . Eng. Chem. (Anal.), 1937, 9, 141.See Ann. Reports, 1935,32, 453, ref. (15).I. M. Kolthoff, J . Amer. Chem. Soc., 1926, 48, 1453.2. anorg. Chem., 1935, 224, 10.F. H. Hurley, jun., Ind. Eng. Chem. (Anal.), 1937, 9, 237; cf. G. Kilde,Dansk Tidsskr. Farm., 1936, 10, 273THEOBALD : INORGANIC ANALYSIS. 481The advantages of using copper vessels for the storage of standardsolutions of acids and alkalis have been discussed as well as theold problem of the preservation of solutions of sodium thiosulphate. 8In the latter case it is now found that 0.1N-solutions containingno preservative are stable if prepared with " aged " distilled waternot more than six months old.The stability of 0-1N-potassiumthiocyanate, recently pointed out by I. M. Kolthoff and J. J.Lingane, lo has received confirmation ;ll the addition of amyl alcoholas a preservative is not recommended.In the standardisation of ceric sulphate with potassium iodideby the acetone method it has been found l2 that the titre varies withthe concentration of acid, but within the range ~~~-2-7"-sulphuricacid, the results are accurate to 0.1%.Ammonium oxalate precipitated from aqueous solution by ethylalcohol and dried at 85-90' has been recommended for the standard-isation of potassium permanganate,13 but I. M. Kolthoff, H. A.Laitinen, and J. J. Lingane l4 now prefer potassium iodide andarsenious oxide as primary standards, rather than sodium oxalate.In agreement with R.M. Fowler and H. A. Bright,15 they findthat McBride's procedure gives high normalities and the best resultswith sodium oxalate are afforded by Fowler and Bright's method,but even here there is a positive error referred to potassium iodide.Finally, H. A. Bright l6 has compared the values obtained in thisstandardisation against arsenious oxide, using potassium iodideor iodate as catalyst, with those given by the new oxalate meth0d.l'For 0.1N-solutions the normalities agreed to within 1 part in 3000,showing that arsenious oxide is suitable as a direct primary standard.The Nicrochemical Detection of Cations and Anions.General.-It is probably true to say that colour reactions for theinorganic ions have now established their worth in analytical chem-istry, and that they should occupy a permanent place in the tech-nical equipment of every analytical chemist.The present positionJ. Lindner, Mikrochem., Molisch Festschr., 1936, 301.See Ann. Reportu, 1935, 32, 454.* P. Horkheimer, Pharm. Ztg., 1936, 81, 1184; cf. E. Tschirch, ibid., 1937,lo See An%. Reports, 1936, 33, 434, ref. (12).l1 F. H. Campbell and G. R. Hook, J . Xoc. Chem. Ind. Victorh, 1936,88,1106.12 D. Lewis, J . Arner. Chem. Xoc., 1937, 59, 1401; cf. Ann. Reports, 1936,13 M. M. Kirilov, J . Appl. Chem. Russia, 1936, 9, 2065.11 J . Amer. Chem. SOC., 1937, 59, 429.1 5 J . Re$. Nut. Bur. Stand., 1935, 15, 493; see Ann. Reports, 1935, 32, 453.16 I n d . Eng. Chem.(Anal.), 1937, 9, 577.17 Fowler and Bright, Zoc. cit.82, 450.33, 447, ref. (36); and ref. (14) below.REP.-VOL. XXXIV482 ANALYTXCAL CHEMISTRY.requires consideration, however, and it is well that some attentionis being directed to the development of existing methods as distinctfrom the breaking of new ground. For inBtance, H. Fritz haspublished further work on methods involving electro-drop analysis,lbut perhaps the best example of development is afforded by thework of 33. L. Clarke and H. W. HermanceY2 who have obtained amuch increased sensitivity in many well-known reactions by amodification of technique. Anyone using these reactions on papersoon discovers that the sensitivity of a test is much affected by theway in which it is carried out, and these authors have emphasisedthis fact.They have aimed a t reducing to a minimum the areacovered by the products of reaction, so as to increase the sensitivity,and they achieve this by means of a capillary burette to control therate of spreading, and thin, close-textured papers impregnated withreagents of low solubility. A factor of considerable importanceis the selection of the precipitating reagent; e.g., a paper impreg-nated with zinc ferrocyanide instead of the more soluble potassiumsalt provides a much improved test for iron. Again, cadmiumxanthate is preferable to the potassium salt as an impregnatingreagent in teat papers for the paper then remains sensitive for months ;moreover, it is more selective and gives sensitive reactiom only withcopper and molybdenum.By such devices as these, a 5-100-foldincrease in sensitivity has been obtained for many familiar reactions,H. Yagoda3 uses another method in order to confine the area ofreaction. He embeds a ring of paraffin wax in the fibres of the paper,leaving a clear space of known size in which to carry out the test.An approximation to the amount of an ion present can thus be moreeasily made, and it is claimed that the metal content of pure copperand nickel salts, for example, can be determined with an accuracyBy removing the silver from glossy or semi-matt bromide paperwith sodium thiosulphate and then soaking the paper with theappropriate reagent, I. M. Korenman also obtains a much increasedsensitivity with various tests.The same medium of silver-freephotographic paper or gelatin has been used 5 in the microchemicalanalysis of very small particles of material. The grains are spreadon a glass plate, attacked by exposure to the vapour of nitric orhydrochloric acid, and then brought into contact with the impreg-nated paper or gelatin, whereupon each grain leaves a coloured spot,of 1-370.1 Mikrochem., 1935,19, 6; 1936, 21,47; 1937, aR,34,168; 23,61; Molischa Ind. Eng. Chem. (Anal.), 1937, 9, 292.6 M. Rey and M. Zeicher, Bull. SOC. chirn. BeEg., 1937, 48, 173.Festschr., 1936, 125 ; 2. anal. Chem., 1929,78, 418.Ibid., p. 79. 4Mikr~hRm., 1936, 21, 17THEOBPLLD : INORGANIC ANALYSIS. 483which, in favourable cases, gives an indication of the amountpresent.The method is reminiscent of that used for the detectionof phosphate in rocks,6 and has been employed by these authorsin the investigation of mineral particles which cannot be identifiedby examination under the microscope.An increased sensitivity is also reached in reactions carried out incapillary tubes by a method described by T. A. Thomson.7 Nosuperiority is claimed in general for the method over drop analysis,but it may have useful practical applications in microbiochemistry.As examples of some recent applications showing the steadyextensions of these reactions in many and varied fields, we maymention the identification of drugs, reactions for some 270 of whichhave been given,s the detection of traces of nickel carbonyl in oilsand gases by virtue of its direct reaetions with dimethylglyoximeand dithizoneYg the distribution of injected heavy metals in celltissues and in the cell contents of plants,lO or that of the chlorideion on the surface of wood or contaminated fabric by means of silverchromate in a gelatin sol a8 a reagent,ll and the detection of thesolubility corrosion of metals, especially zinc, copper, tin, brass, andgun-metal, by sea-wster.12Separation into Groups.-Several schemes that combine a separa-tion of cations into groups with the use of drop reactions have beenput forward from time to time,13 but they appear to have beenneglected. The tendency has been to make short cuts and to avoida separation, a course of action that has many dangers.Indeed,the more one’s experience of these tests in applied work widens themore one realises how real these dangers are and how unsoundthis course must be.It, is a healthy sign that attention is againbeing direeted to the necessity for a preliminary separation in manycases. Thus, a procedure recently given for the qualitative analysisof the commoner cations on a semi-micro scale separates them intotheir usual groups and then applies drop reactions directly for the6 See F. Feigl, “ Qualitative Analyse mit Hilfe von Tupfelreaktionen,”1935, p. 456.7 Mikrochem., 1937, 21, 209.8 C. A. Rojahn et al., Pharna. Zentr., 1937, 78, 81, 127, 146.9 B. Steiger, Mikrochem., 1937, 22, 216. See idem, Petroleum, 1937, 33,No. 27, Motoreenbetr., 10, 3, for the detection of tetraetlqd-lead and nickelcarbonyl.10 S.Pritt, Mikmchem., Molisch Festschr., 1936, 342; see also B. Broda,Wiado9la. fm., 1936, 63, 0, 15.11 F. G. Lennox, J . Proc. Austral. Chem. Inst., 1936, 3, 313.12 W. R. G. Atkins, Trans. P a r h y SOC., 1937, 33, 431.13 See F. Feigl, op. cit., p. 345; C . J. Engelder, T. H. Dunkelberger, andW. J. Schiller, “ Semi-micro Qualitative h l y s i s , ” J. Wiley and Sons, NewYork, 1936484 ANALYTICAL CHEMISTRY.detection of the ions concerned.la Much time can thus be saved,especially in Group 11. The most important work, however, inthis connexion is the continuation of a series of papers by A. A.Benedetti-Pichler and W. F. Spikes l5 mentioned in last year’sReport.16 Details of a complete scheme for the analysis of theammonium sulphide group, including gallium, indium, and therare earths, etc., on a milligram scale using less than 1 ml.ofsolution and following, in the main, the macro-separations ofNoyes and Bray, have been worked out. Unusual difficulties wereencountered in the analysis of the chromium group and in the detec-tion of tungsten, and the authors are of opinion that, at present, nochemical method for the detection of small amounts of this elementin the presence of relatively large amounts of chromium, uranium,vanadium, and phosphate ion can be recommended. Many differentschemes for the separation of these elements were investigated, andare summarised in a second paper; l7 both these papers are ofconsiderable interest. *This work has been done on a milligram scale, but in a later paperA.A. Benedetti-Pichler l8 has described a general working techniqueapplicable to the qualitative analysis of 1 pg. of solid material.The chemical separations are carried out in cones of 0.5 c.mm.capacity, and the transfer of solutions is effected by means ofmicrurgical pipettes operated by a hypodermic syringe. Most ofthe manipulations have to be done under observation with a low-powered microscope. Working procedures are described in theanalysis of 0-01 c.mm. of a solution containing 0.1 p.g. of antimonyand 0.01 pg. of bismuth. The author states that the separationsobtained have the same sharpness as in the analysis of larger amounts,and although the operations at present are rather time- consuming,they have the merit of demonstrating that even on this small scalethe familiar tests are still valid.For the micro-detection of siZver, theblue colour formed with o-tolidine is said to develop in the presenceof not leas than 3 x 10-8 g.of this metal.l9 To the numeroussensitive tests already available for copper must be added the darkred colour given by cupric salts with potassium bromide and sul-14 J. H. Winkley, L. K. Yanowski, and W. A. Hynes, Mikrochern., 1936,21, 102.Drop Reactions.-Cations.1 5 Mikrochem., Molisch Festschr., 1936, 3. l6 P. 453.1 7 A. A. Benedetti-Pichler and TY. F. Spikes, Mikrochem., Molisch Festschr.,18 I n d . Eng. Chem. (Awal.), 1937, 9, 483.1s L. M. Kulberg and S. B. Serebriani, J .Gen. Chem. Russia, 1936, 6, 1335.* See also A. A. Benedetti-Pichler and J. R. Rachele, I n d . Eng. Chem.1936, 36.(Anal.), 1937, 9, 589, for the selenium group of Noyes and BrayTHEOBALD : INORGANIC ANALYSIS. 485phuric acid,20 the yellowish -brown precipitate obtained with anilinethiocyanateY2l the pink to purple colour obtained with -urobilin,22and the catalytic acceleration of the atmospheric oxidation andrecoloration of phen~lphthalin.~~ The last test is carried out in thepresence of potassium cyanide and is reasonably selective : it isrecommended by the authors for the detection of copper in naturalwaters.Satisfactory drop reactions for cadmium are scarce, but the needfor a good reagent seems to have been met by F. P. Dwyer,24 whoutilises the red lake formed between cadmium hydroxide andp-nitrodiazoaminoazobenzene (" Cadion ").Used as a drop reactionon paper, the test is selective and highly sensitive ; only silver andmercury ions have previously to be removed, and other interferingelements are provided against by the addition of Rochelle salt.*The solution of the reagent showed no sign of deterioration after2 months' keeping.Osmium, as the tetroxide, gives sensitive colourations on filterpaper impregnated with an acetic acid solution of potassium ferro-cyanide or benzidine, and by boiling the solution and directing thevapour containing the tetroxide on to the reagent, traces of osmiumare said to be detectable in the presence of all other cations.25Less sensitive colours, blue or orange, respectively, are obtained whena solution of sodium osmate is treated with pyrogallol or withephedrine hydrochloride .26Rhenium is detected by utilising the fact that reduction oftellurate by stannous chloride is catalysed by ReO,'.A blackprecipitate is obtained with 2.5 x lo-* g. of rhenium in 0.05 ml.Vanadium, tungsten, arsenic, selenium, osmium, and molybdenuminterfere above certain limiting concentration^.^^The red colouration observed in blue light when hydroxynaphth-acenequinonesulphonic acid in sulphuric acid is added serves as asensitive reaction for germanium.28The reduction of the selenite ion by ammonium thiocyanate in the20 S. Augusti, Mikrochem., 1937, 22, 139.21 F. P. Dwyer and R. K. Murphy, J . Proc.Austral. Chern. Inst., 1937,4, 334.22 G. Bertrand and L. de Saint-Rat, Mikrochim. Actu, 1937, 1, 5.23 I. M. Kolthoff and J. J. Lingane, Mikrochem., Molisch Festschr., 1936,274.24 J . Proc. Austral. Chem. Inst., 1937, 4, 26; J . SOC. Chem?. Ind., 1937, 56,25 N. A. Tananaev and A. N. Romanjuk, 2. anal. Chem., 1937, 108, 30.26 S. 0. Thompson, F. E. Beamish, and M. Scott, Ind. Eng. Chem. (Anal.),37 N. S . Poluektov, J . Appl. Chem. Russia, 1936, 9, 2312.2 8 Idem, ibid., p. 2302.* The Reporter now prefers this test t o that with dinitrodiphenylcarbazide7 0 ~ .1937, 9, 421.and it has proved very satisfactory486 ANALYTICAL CHEMISTRY.presence of hydrochloric acid has been employed as a qualitativetest for selenium. Reduction to the red form is rapid and completein 6~-hydrochloric acid at the boilkg point.Interference is causedby ferrous iron, tervalent antimony, and stannous tin, but not byferric iron, lead, copper, or mercuric mercury, e t ~ . ~ ~ Por the sameelement F. Feigl and V. Demant 30 utilise the red to reddish-violetcolour resulting from the oxidation of as-diphenylhydrazine in aceticacid by the selenite ion. Other oxidising agents such as iodate,permanganate, and peroxides must first be destroyed by treatmentwith hydrochloric acid, and the effect of those such as ferric iron,copper, molybdate, and tungstate, must be prevented by conversioninto a complex oxalate. Tellurates and tellurites do not react.The test is applicable to elementary selenium, to selenides or toselenates after conversion into selenite.*2 : 3 : 7-Trihydroxy-9-methy1-6-fluorone has been suggested as areagent for antimony. At a p H of approx,4, ter- and quinque.valent antimony ions give bright red precipitates in a hydrochloricacid solution or in 10% nitric acid in the presence of tartaric acid.It is claimed that antimony can be detected with certainty in mineralscontaining arsenic, bismuth, et c.31A neutral or slightly acid solution containing as little as 4 x lO-7g.of moZybdenumt in 0.04 C.C. gives a reddish-violet colouration with2 : 2‘-dipyridyl in ethyl alcohol and stannous chloride.32 Rhenium,vanadium, and quinquevalent arsenic do not interfere, but in thepresence of tungsten, tartaric acid should be added. Iron must,of course, be absent.In an investigation of the serviceability ofother methods suggested for the detection of molybdenum, A. C.Rice and L. A. Yerkes 33 find that the thiocyanate-stannous chloridemethod is the most sensitive, with the potassium ethylxanthatemethod ranking next to it. In both ca,ses sensitivity is increasedby extraction with ether.29 H. A. Ljung, Ind. Eng. Chem. (Anal.), 1937, 9, 328.30 Mikrochim. Acta, 1937, 1, 322.31 R. Duckert, HeZv. Chim. Acta, 1937,20,362 ; P. Wenger, R. Duckert, and52 A. S. Komarovski and N. S . Poluektov, J. Appl. Chern. Russia, 1937,33 U. S , Bur. Mines, Rept. Invest. 3328, 1937, p. 37. * The danger of loss in selenium analyses owing to volatilisation on evapor-ation with hydrochloric acid solutions of an acid concentration greater than6~ appears to the Reporter to have been overlooked in the procedure recom-mended by the authors for the detection of selenium in minerals (for data,see Hillebrand and Lundell, “ Applied Inorganic Analysis,” 1929, p.259,and K. Briickner, 2. anal. Chem., 1933, 94, 305). t For a fluorescence reaction with cochineal see L. Szebelledy and J. J b d ~ ,Mikrochim. Acta, 1937, 1, 46.C1. P. Blmcpain, ibid., p. 1437.10, 565; Mikrochim. Acta, 1937, 1, 264THEOBALD INOBGANIC AHALYSIS. 487Traces of gold can be detected by means of the blue colour that isgiven with leuco-nitrobrilliant-gree11.3~ In the presence of colouredions, the blue colour is rendered visible by extraction with chloro-form in which it is soluble. The reaction has been applied tocolorimetric determinations.phsanilic acid forms a reddish-brown to pink colour with cericions in dilute acid solution, and may meet the need for a good testfor this element.Cerous ions, the rare earths, and many otherions (e.g., those of titanium, ferric iron, manganese, tungstate,molybdate) do not interfere. Chromium and cobalt may beinimical on account of their colour, and fluoride must be absent.Zirconium is also precipitated, and excess of reagent tends to pre-cipitate thorium .s5 The chocolate-coloured precipitate obtainedwith both ter- and quadri-valent cerium and morphine hydro-chloride in the presence of an excess of ammonia can also be usedas a drop reaction.362 : 4-Dihydroxyacetophenone is an addition to the qualitativereagents for iron.37 The sensitivity (0.002 mg.per ml. of solution)compares well with that of ammonium thiocyanate or potassiumferrocyanide, and, unlike 2 : 2'-dipyridyl, the reagent is neithercostly nor difficult; to prepare. An alcoholic solution produces a,red colour with ferric iron in a weakly acid solution and the inter-ferences from other ions are not marked. Phosphates (and, presum-ably, fluorides) must be absent.A test for aluminium is provided by the orange-red fluorescenceobtained with Pontachrome-blue-black-R in ultra-violet light.Highly-coloured ions should be removed by means of sodiumhydroxide, but beryllium does not interfere.3* The sensitivity ofthe reaction of aluminium with eriochromcyanin-R in the presenceof other ions has also been rec0rded.3~ In this case beryllium doesgive a similar reaction, but by a suitable procedure g.ofaluminium can be identified in the presence of 500 times as muchberyllium.The sensitivity of the potassium periodate test for manganese ismuch increased by the introduction of p-tetramethyldiamino-diphenylmethane,m which is catalytically oxidised to a blue productby traces of permanagnate formed from the manganese ion and theperiodate. The same effect has been attained by the substitution34 L. M . Kulberg, Zuvod. Lab., 1936, 5, 170.35 J. F. Miller, I n d . Eng. Chem. (Anal.), 1937, 9, 181.36 F. M. Schemjakin, Compt. rend. Acad, Sci. U.R.S.S., 1937,14, 115.37 S. R. Cooper, Ind. Eng. Chem. (Anal.), 1937, 9, 334.58 C.E. White and C. S. Lowe, ibid., p. 430.3Q E. Eegriwe, 8. anal. Chem., 1937, 108, 268; 1929, 76, 440.40 F. Feigl, op. cit., p. 228488 ANAL1 TICAL CHEMISTRY.of p-phenetidine for the tetramethyl base. A violet-red colourresults, and chloride, iron in the presence of sodium fluoride, cobalt,and chromium are said not to interfere. With chromate present,the sensitivity is reduced and more periodate is consumed.41The same base in the form of its hydrochloride furnishes, togetherwith potassium ferricyanide, a sensitive drop reaction forA large excess of the alkaline earths, magnesium, sodium, potassium,or ammonium has no effect on the blue colouration produced.New work on magnesium concerns the blue colour obtained withbenzoazurin-G-a test that is subject to interference by manyions, h0wever.4~Anions.-In the fluorescein test 44 for bromide in the presence oflarge amounts of chloride, aqueous chromic acid is preferred45to potassium permanganate and sulphuric acid 46 since it causesless general bleaching of the fluorescein and is easier to handle.Successive extraction of a solution with chloroform and hydrogenperoxide, which liberates only iodine, and with aqueous nitrousacid and chloroform permits the detection of 1 x g.of iodideand bromide, respectively.The xylenol method for nitrate 47 has been modified so as to detect0-001 mg. of NO,’ by the yellow to red colouration formed when5-nitro-m-xylenol is distilled into dilute sodium hydroxide. Per-oxides and nitrites must first be destroyed, and alkali sulphidesremoved by means of copper sulphate.I n a modification of the Griess-Ilosvay test for nitrites, substitu-tion of a-naphthylamine by dimethylaniline leads to formation ofmethyl-orange, which, of course, is turned red by the acid present.48The sensitivity and selectivity of the alizarin test for boric acid 49are both said to be improved by examination in ultra-violet light.50According to E.SchroerY5l sulphur in all its compounds is reducedto hydrogen sulphide by nascent hydrogen. Organic compoundsmay be converted into mercaptans, detectable in minute amountsby their odour. The hydrogen sulphide is best detected by theblue luminosity that it confers on the flame of burning hydrogen.4 1 L. Szebellhdy and M . Bhrtfay, Z .anal. Chem., 1936, 106, 408.42 L. SzebellBdy and S. Tanay, ibid., p. 342.43 E. Eegriwe, ibid., 1937, 108, 34.44 Cf. F. Feigl, op. cit., p. 277.4 5 R. G. Aickin, J . Proa. Austral. Chem. Inst., 1937, 4, 267.4 6136, 90.4 7 F. Werr, 2. anal. Chem., 1937, 109, 81.4 8 J. C. Giblin and G. Chapman, Analyst, 1936, 61, 686.49 F. Feigl and P. Krumholz, Mikrochem., Pregl Festschr., 1929, 79.60 L. Szebellhdy and S. Tanay, 2. anal. Chem., 1936,107, 26.51 Mikrochem., 1937, 22, 338.Cf. R. Lorenz, E. Grau, and E. Bergheimer, 2. anorg. Chem., 1924THCEOBALD : INORGANIC ANALYSIS. 489Selenium and tellurium appear to be the only elements likely tobe seriously detrimental to the test.The Use of the Term “ Speci$c.”-In the above-mentioned dropreactions, the limiting amount of an element or ion that can bedetected is generally less than g.per drop. The actualsensitivities found are those for a solution containing only the ionin question, but it must always be remembered that this is themost favourable case, and that in practice the presence of otherions usually necessitates a modification of procedure which, moreoften than not, involves a loss in sensitivity. Almost withoutexception each test is subject to interference from the presence ofother ions, and it cannot be too strongly emphasised that the possi-bility of these interferences occurring must be taken into considerationbefore a test is applied. The ideal of a reaction that is “ specific ”in the true sense of the word is far from being realised in many ofthese reactions; indeed, it is hardly to be expected that it should.This point has been emphasised in the two preceding Reports,52and as a result of the last note the following announcement has beenmade, by the Committee appointed by the International Unionof Chemistry for the study of new analyticaJ reagents, concerningthe use of the terms “ specific ” and “ selective ” : “ The Committee.. . has decided to differentiate between specific and selectivereactions (and reagents) and recommends this convention for generaluse. Reactions (and reagents), which under the experimentalconditions employed are indicative of one substance (or ion) only,are designated as speci$c, whilst those reactions (and reagents)which are characteristic of a comparatively small number of sub-stances are classified as selective. From this it follows that it ispermissible to describe reactions (or reagents) as having varyingdegrees of selectivity; on the other hand a reaction (or reagent)can be only specific or not specific.” 53It is to be hoped that this recommendation will be followed, foronly by some such means can a correct statement of the facts,which is at present lacking, be attained.It would be deplorableif, through laxity of expression or a misunderstanding of terms,some of these reactions should undeservedly fall into disrepute,and as a result their utility in chemical analysis should not beexploited to the full.The Behrens Tests.-As distinct from colour reactions, thesetests, involving the recognition of crystalline precipitates under themicroscope, still find favour in certain quarters, especially amongmineralogists in the United States.These, as well as certain62 Ann. Reports, 1936, 82, 471; 1936, 33, 453.63 See Analyst, 1937,62, 568; Chem. and Ind., 1937,56, 636490 ANALYTICAL CHEMISTRY.chemists whose work is connected with mineralogy, will welcometwo recent papers concerning these tests. In the first,64 the inter-ferences in size, shape, or colour of the crystals produced in certainstandard tests of the U.S.. Geological Survey’s scheme 55 for thedetection of elements in ore minerals are hlly described, and arediscussed with the object of avoiding the pitfalls attendant onthe use of such methods.These pitfalls are numerous and mayoften lead to error for, as the authors point out, in skilled andexperienced hands changes in colour or form, or possibly a negativetest, occur and make interpretation difficult. This strengthens anopinion expressed in an earlier Report,56 and for the general run ofminerals, at least, it is preferable in most cases to use colour reactionsinstead of the Behrens tests.*With the precious metals the case is different. The colour re-actions t for these need further development and the Behrenstests are still of great vdue, all the more so as these metals,with the exception of palladium, form an easily-segregated groupby virtue of their insolubility in dilute hydrochloric or nitricacid.The second of the papers 57 mentioned above deals first with theindividual reactions of platinum, palladium, rhodium, ruthenium,iridium, osmium, and gold with ammonium dichromate, benzidine,thiourea, pyridine hydrobromide, etc., and secondly with theinterferences that may be produced by one of these metals in thepresence of another.The most suitable tests for the identificationof these metals in their minerals and alloys are indicated.The characteristic habits of the silver compound with hexa-methylenetetramine, of copper sulphate and potassium bromide withantipyrine, and of barium hydroxide with caffeic acid are amongthe tests described 58 for numerous substances both organic andinorganic.I. M. Korenman 59 employs the Behrens tests for the detection ofcopper, tin, lead, antimony, bismuth, silver, and nickel in alloys,64 H. J. Praser and R. M. Drayer, Amer. Min., 1937, 22, 949.6 6 Bulletin No. 825.66 Ann. Reports. 1935, 32, 471.67 H. J. Fraser, Amer. Min., 1937, 22, 1016; cf. aleo Ann. Reports, 1935,68 L. Rosenthaler, Mikrochem., 1937, 21, 215.68 Zavod. Lab., 1937, 6, 308. * The Reporter’s experience is that these tests are not so suitable, even forpost-graduate students, as the colour reactions, for which previous experienceis not essential.t The utility and efficiency of some of these tests are discussed by S. 0.Thompson, F. E. Beamish, and M. Scott, Ind. Eng. Chern. (Anal.), 1937,9, 421.32, 474, ref. (66)THEOBALD INORGANIC ANALYSIS. 491and with S. S. Messonshnik 6o records data for the limiting amountsof lead detectable with the well-known triple nitrite test and withother reagents.Other investigations deal with tetraethylammonium iodide as ilreagent for quinquevalent antimony (purple, hexagonal plates) andbismuth (dark amber, triangular plates) ,61 the identification oftellurium by the formation of yellow crystals of the bromide orblack crystals of the tetraiodide, 62 and the crystalline Precipitatesof characteristic habit formed with sparteine, ammonium thio-cyanate, and cobalt or ferric ~ a l t s . ~ 3W. Geilmann and W. Wrigge 64 describe the crystalline doublesalts, suitable for identification microscopically, given by rhenium(as ReCl, or H,ReCl,) with reagents such as potassium, rubidium,or casium chloride, and the hydrochlorides of certain organic bases.After a discussion of many confirmatory tests for beryllium which,with the exception of the quinalizarin test, they consider to beunsatisfactory, A. A. Benedetti-Pichler and W. F. Spikes 65 preferto convert beryllium into its acetate which, on sublimation, yieldseasily-recognisable, well-formed crystals of the basic acetate. Asa good confirmatory test for gallium they recommend the formationof an alum with caesium chloride containing a trace of potashalum.In order to differentiate between chromate and dichromate ions,advantage is taken of the fact that with [Co(NH,),]Cl, these ionsyield [Go( NH,) ,]Cr 04c1 and [ co( NH,),] ( cr,o,)s, respectively, ofvery different crystalline form.66 The same reagent providesrapid tests for dithionate, ferrocyanide, ferricyanide, iodate, sulpho-salicylate, etc., and gives characteristic precipitates also withphosphomolybdate, phosphotungstate, tellurite, cobaltinitrite,nitroprusside , and other ions more common thanBook-A new edition, the ninth in English, of the qualitativesection, Vol. I, of Treadwell and Hall's text-book has recentlybeen published. In bringing this well-known work up-to-date,many changes and improvements have been made.W. R. Schoeller has published his monograph on tantalum andniobium under the title " The Analytical Chemistry of Tantalum and60 Zavod. Lab., 1936, 5, 168.61 F. T. Jones and C. W. Mason, I n d . Eng. Chem. (Anal.), 1936, 8, 428.62 G. DenigBs, Compt. rend., 1937, 204, 1256.68 A. Martini, Mikrochim. Acta, 1937, 1, 164.64 2. anorg. Chem., 1937, 231, 66.6 5 Mikrochem., 1937, 21, 268; c f . idem, ibid., Molisch Festschr., 1936, 23.6 6 M. G. Malko, L. K. Yanowski, and W. A. Hynes, Mikrochem., 1936,67 W. A. Hynes and L. K. Yanowski, Mikrochem., 1937, 23, 1.21, 57492 ANALYTICAL CHEMISTRY,Niobium. The Analysis of their Minerals and the Application ofTannin in Gravimetric Analysis ” (Chapman and Hall Ltd., 1937).It is a work that will be needed whenever an anatlysis of theseminerals has to be undertaken.L. S. T.H. F. HARWOOD.L. S. THEOBALD.F. TWYMAN

ISSN:0365-6217    

DOI:10.1039/AR9373400454

出版商:RSC    

年代:1937

数据来源: RSC

摘要:

INDEX OP AUTHORS’ NAMES.ABAUIE, P., 88.Abbasy, M. A., 407, 408.Abel, E., 104.Abkin, A., 250.Abraham, E. P., 305.Adam, H., 26.hdams, A. R. D., 424.Adams, R., 221, 222, 256.Adkins, H., 223, 224, 225, 226, 227,Aickin, R. G., 65, 488.Aidinjan, N., 471.Ainley, A. D., 349.Aivasov, B. V., 49.Akerlof, G., 96, 100.Akeroyd, E. I., 57, 877.Alber, H., 466.Albers, V. M., 370.Alexander, A. E., 53.Alexander, W. A., 267, 278.Alfvh, H., 29.Alimarin, I., 474, 476.Allard, J., 239, 240.Allchorne, E., 410, 412.Allen, A. O., 278.Allen, C. F. H., 263, 391, 392.Allison, F. E., 452.Allmand, A. J., 61, 62, 63, 65.Allsopp, A., 447.Altar, W., 81.Amaldi, E., 14, 16.Amberg, C. R., 163.Ammon, R., 405.Anchel, M.. 262.Andersag, IS., 353.Anderson, A.A., 439.Anderson, C. D., 28.Anderson, E., 299.Anderson, F. W., 409.Anderson, J. S., 32, 34, 40, 169, 189.Andreev, E. A., 49.Anson, M. L., 319.Aoki, H., 20.Applebey, M. P., 110.Appleyard, (Miss) M. E. S., 55.Aradine, P. W., 470.Arakatsu, B., 28.Archer, C. T., 35.Archer, H. E., 423.Archer, N., 417.228.Angus, w. R., 200.Ardenne, fil. voii, 88.Arii, K., 37.Arkel, A. E. van, 86, 180.Armstrong, G., 109.Armstrong, K. F., 239.Armstrong, W. D., 476.Arndt, F., 263.Arnim, K. von, 357.Amott, W. M., 417.Arsdell, P. M. van, 260.Art agave y t ia - Allende, R . , 42 4.Asahina, Y., 394.Asai, T., 441.Ashley, J. N., 450.Askew, F. A., 337.Askey, P. J., 234.Astbury, W. T., 303, 311, 316, 320,322, 326, 453.Astin, S., 239.Aston, F.W., 7.Atkin, L., 401.Atkin, W. R., 315.Atkins, W. R. G., 483.Audrieth, L. F., 323.Auger, P., 27, 28.Augspurger, L., 394.Augusti, S., 485.Aumiiller, W., 333.Auwers, K., 329.Ayling, E. E., 258, 259.Ayres, F. D., 97.Baars, E., 107.Babers, F. H., 296.Babha, H. J., 26.Bacharach, A. L., 409, 410, 412.Bacher, R. F., 9, 22.Bachmann, W. E., 284.Backer, H. J., 242.Badger, R. M., 61, 92, 198, 199, 213.Badoche, M., 389, 392.Biickstrom, H. L. J., 71, 234.BLihr, K., 249.Baerstein, H. D., 315.BaetslB, R., 446.Baeyer, A. von, 242.Bagley, D. S., 24.Bailey, C. F., 380.Bailey, C. R., 200.Bailey, K., 311.49494 INDEX OF AUTHORS’ NAMES.Bailey, K. C., 233.Baker, A. Z., 414.Baker, F., 408.Baker, R. T., 394.Baker, W., 219.Baker, W.N., 36.Baker, W. O., 184.Balas, T., 393.Baldeschwieler, E. L., 222.Bamford, C. H., 55, 56, 270, 276, 283.Bancroft, W. D., 111.Banerjeo, K., 189.Banerjee, S., 189.Banerjee, T., 72.Bannister, F. A., 162.Barak, M., 56, 270.Barber, A., 26.Barbier, P., 394.Barchiewitz, P., 92.Barger, G., 353, 357, 358.Barham, H. N., 443, 448.Barinova, S. A., 446.Barker, E, F., 204.Barker, H. A., 451.Barksdale, J., 96.Barnes, S. W., 13.Barnes, W. H., 36.Barr, J. B., 423.Barr6, R., 389.Barrer, R. M., 35.Barrett, J. W., 262.Barrett, P. A., 369, 371.Barrie, M. M. O., 412.Bhrtfay, M., 488.Bartholom6, E., 35, 80.Barton, H. A., 22.Barton-Wright, E., 427.Bartunek, P., 204.Barwick, H., 8, 43.Bateman, H., 171.Bates, J.R., 71, 280.Baud, J., 343.Baudisch, O., 435.Bauer, E., 79, 84.Bauer, K., 386.Bauer, S. H., 92, 152, 198, 213.Baughan, E. C., 50.Baule, B., 468.Baur, L., 299,300.Bawden, F. C., 428, 431.Bayliss, N. S., 65.Beach, J. Y., 163, 177, 199, 209.Beale, 23. P., 427.Beamish, F. E., 485, 490.Beazley, W. B., 46.Beck, P. A. A. van der, 234.Becker, M., 296.Beckman, A. O., 68, 69.Beckwith, T. D., 451.Beebe, R. A., 35.Beevers, C. A,, 167.Bghounek, O., 37.Behr, G., 443, 444.Beintema, J., 163.Belcher, D., 103.Belchetz, L., 265, 271.Bell, (Miss) J. C., 345, 346.Bell, R. P., 37, 45, 50, 51.Bendixen, H. C., 413.Benedetti-Pichler, A. a., 465, 468,Benedicks, C., 466.Benedict, W. S., 35, 49, 68, 70.Bennet-Clarke, T.A., 447.Benoit, F., 149.Benoy, M. P., 287.Benson, A. N., 9.Berdennikowa, T. P., 150.Berg, C. P., 313.Bergel, F., 242, 353, 354, 355, 356,Berger, H. W., 285.Bergheimer, E., 48%.Bergmann, E., 74, 243, 246, 249, 339.Bergmann, F., 339.Bergmann, M., 290, 310, 313, 314,Bergstrom, S., 294, 295.Bergstrom, F. W., 248.Berman, H., 164.Bernal, J. D., 80, 82, 89, 90, 173, 199,Bernhauer, K., 441, 442, 445.Bernreuther, F., 65.Berthoud, A., 66.Bertrand, G., 485.Best, A. P., 200.Best, R. J., 428.Bethe, H. A., 7, 9, 20, 22, 23, 25.Bettag, L., 251, 256.Bewilopa, L., 171.Beyer, H., 366.Beyer, H. G., 23.Beyer, J., 157.Beynon, J. H., 259, 340.Bhargava, P. N., 66.Bhattacharyya, S. K., 72.Bilton, J.A., 372.Biltz, W., 146, 162.Birch, S. F., 248.Birch, T. W., 401.Birkinshaw, J. K., 450.Birnthaler, W., 38.Biron, A,, 49.Birrell, K. S., 394.Biscoe, J., 427.Blacet, F. E., 58, 274, 277, 278.Blackett, P. M. S., 27.Blanchard, K. C., 439.Blanchard, L., 223.Blancpain, C. P., 486.Blanke, E., 222.Bleakney, W., 34.Bleick, W. E., 77.Blink, G. J., 413.Bliss, E. A., 422.484, 491.401, 411.315, 316, 320, 323, 324, 326.329, 428INDBX OF AUTHORS’ NAJHES. 495Blix, G., 295.Bloch, B. M., 57.Bloch, F., 23.Block, R. J., 314.Blokker, P. C., 35.Bloom, M. C., 160.Blumann, A., 236.Blum-Bergmann, O., 249.Blumenthal, E., 43.Boam, J. J., 346.Bock, F., 409.Bock, H., 300.Bodenstein, M., 47, 64, 65, 66, 72, 137,Bodroux, D., 261.Bodson, H., 36.Boedtker, E., 260.Boeseken, J., 232, 242, 251.Bohme, H., 242.Borner, K., 285.Boersch, H., 199.Boz, G., 88.Bogert, M.T., 234.B o b , N., 9.Bohrens, 0. K., 325.Bolland, J. L., 34, 69, 71.Bommer, H., 124, 145.Bonhoeffer, K. F., 40, 60, 51, 52, 271,Bonneman, P., 120, 122.Bonner, T. W., 22.Bonnet, R., 445.Borek, E., 263.Borgwardt, E., 239, 240.Born, M., 77, 78.Borst, J. G. G., 423.Bose, P. K., 344, 368.Bosschieter, G., 90.Boswell, M. C., 253.Bothe, W., 12, 20, 26.Bott, H. G., 297.Botti, E., 159.Boull6, A., 119.Bourguel, M., 223.Bouveault, L., 394.Bovarnick, M., 292.Bovet, D., 421.Bowden, F. P., 107.Bowen, E. J., 55, 137, 234.Bowen, I. S., 27.Bowles, J. A. C., 131.Bozorth, R.M., 180.Bradbrook, E. F., 372.Brady, 0. L., 263.Bragg, (Sir) W. H., 190, 196.Bragg, W. L., 159, 196.Brandt, A., 135.Brasefield, C. J., 10.Brassew, H., 168.Bratu, E., 104.Brauer, G., 62.Braun, J. von, 234, 350.234.273.Boyd-Barrrttt, H. S., 285.Braune, H., 180.Braverman, M. M., 62.Breckpot, R., 460, 461.Breit, G., 12.Breitner, S., 378.Brenard, G., 68.Brenschede, W., 72, 138.Bretscher, E., 22.Brickwedde, F. G., 23, 35.Bridge, W., 347.Bridgman, J. A., 147.Bridgman, P. W., 140.Bright, H. A., 481.Brillouin, L., 80.Briscoe, H. V. A., 32, 34, 40.Brockmann, H., 348, 409.Brockway, L. O., 163, 177, 180, 196,197, 198, 199, 208, 209, 210, 213,214.Broda, B., 483.Brodski, A. E., 41.Brtansted, J. N., 60, 52, 97.Broser, W., 295.Brown, A.G., 67.Brown, A. S., 105, 107.Brown, J. H., 222.Brown, R. S., 36.Brubaker, G., 10.Bruce, W. F., 222.Bruck, J., 344.Bruckner, K., 486.Brunger, K., 147.Brukl, A., 123, 128, 130.Brull, R., 443, 444.Brungger, H., 328, 329, 330, 340.Brunner, O., 330.Bub, K., 384.Buchman, E. R., 353.Buck, J. H., 13.Buckingham, R. A., 22, 77.Buckton, G. B., 243.Budnikov, P. P., 470.Burgel, E., 295.Buerger, M. J., 160, 161, 162.Bunke, H. J., 436.Buogo, G., 404.Bmwoy, A., 145, 168.Burch, C. R., 221.Burcham, W. E., 14.Buret, R., 393.Burg, A. B., 151.Burger, A., 227.Burgers, W., 300.Burk, N. F., 306, 308.Burkhardt, G. N., 52.Burnett, R. leG., 51.Burnham, J., 91.Burtner, R. R., 260, 261.Burton, M., 58, 59, 74, 274, 278.Burwell, J.T., 178.Busch, M., 379.Buswell, A. M., 91, 213.Butement, F. D. S., 129, 131496 I N D ~ X OF AUTHORS’ NAMES.Butenandt, A., 230.Butkevitsch, V. S., 447.Butler, J. A. V., 33, 51, 107, 108, 109,Buttenschon, W., 358.Buttle, G. A. H., 421, 422.110.Caglioti, V., 166.Cahill, W., 296.Cahn, R. S., 346.Calas, R., 38.Calcagni, G., 121.Caldwell, J., 430.Caley, E. R., 473.Calhoun, G. M., 47.Callow, R. K., 239.Calloway, N. O., 251, 253, 254, 265,Calvery, H. O., 315.Calvin, M., 35, 41.Campbell, F. H., 481.Campbell, H. A., 299.Campbell, R. W., 112, 273, 274.Campion, J. E., 410.Cantieni, R., 71.Cantuniari, I. P., 253, 256, 257, 258.Capron, P., 214.Carey, C. L., 436, 437.Carius, L., 137.Carlson, J.F., 26.Carlson, W. W., 66.Carman, E. F., 337.Carpenter, E. L., 96.Carroll, H., 23.Carruthers, J. E., 71, 277.Cathcart, W. H., 52.Cauquil, (Mlle.) G., 38, 239.Cams, E., 129.Centnerszwer, M., 52.Cerkovnikov, E., 350, 351.Chadwell, H. M., 280.Chadwick, J., 10, 22.Chaix, P., 438, 439.Challinor, S. W., 297.Chamberlain, E. A. C., 49.Champetier, G., 8, 43.Champion, F. C., 26.Chang, T. L., 33, 34, 36.Chang, T. S., 84.Chang, W. Y., 10, 14.Chao, J. C., 339.Chapman, A. T., 72.Chapman, D. L., 64.Chapman, G., 488.Chargaff, E., 292.Charles, A. F., 294.Chattaway, F. W., 145.Chavanne, G., 237.Chester, K. S., 432.Chevallier, A., 405.Cheymol, J., 448.Chicos, I., 257.261.Child, W.C., 228.Chittum, J. P., 38, 39, 51.Chiummo, (Signa.) C., 223.Cholak, J., 461.Cholnoky, L. von, 220, 222.Chong, S. H., 66.Choron, Y., 405.Chow, B. F., 384.Chrhtien, P., 139.Christeleit, W., 291, 312.Christensen, L. M., 443.Christiani, A. F. von, 249.Chistiansen, J. A., 44, 52.Christman, C. C., 292.Chrzaszcz, T., 445.Cior&escu, E., 257.Claisen, L., 228.Clark, G. L., 195.Clarke, B. L., 482.Clarke, H. T., 262, 263, 353.Clemo, G. R., 350, 359, 365.Clews, C. J. B., 188, 212.Cline, J. K., 355, 356, 401.Clusius, K., 35, 39, 114, 179.Clutterbuck, P. W., 450.Cockcroft, J. D., 24.Cockett, A. H., 36.Coffin, C. C., 46.Cohen, S. L., 328, 333.Cohn, E. J., 303.Cole, S. S., 161, 163.Colebrook, L., 421, 422, 423.Colla, C., 168.Collins, F.J. E., 183.Collins, J. R., 90.Colonius, H., 243, 244.Comet, (Mlle.), 237.Conant, J. B., 243, 378, 380, 384, 385.Connor, R., 225.Constable, J. R., 10.Cook, A. H., 220, 263, 369, 373.Cook, G. A., 71.Cook, J. W., 257, 261.Cook, M. A., 95, 96.Cook, R. P., 420.Cooke, T. F., 99.Cooper, B. S., 174.Cooper, S. R., 487.Copping, A. M., 415.Corbeau, L., 300.Corbet, R. E., 399.Corey, R. B., 427, 428, 431.Cork, J. M., 15, 17.Cornthwaite, W. R., 287.Coryell, C. D., 383.Cosyns, M., 29.Couch, H. B., 256.Covert, L. W., 223, 225, 226.Cowperthwaite, I. A., 94, 96.Cox, E. G., 145, 168, 181.Cox, E. H., 254.Cox, G. J., 313.Cox, R. G., 54INDEX OF AUTHORS’ NAMES. 497Craggs, H. C., 61, 62, 65.Cramer, H.I., 225.Crane, H. R., 12, 13, 24, 26.Crawford, B. L., 179.Crawford, C. C., 90.Criegee, R., 231, 232, 233, 236, 238.Crist, R. H., 47.Croad, G. F., 480.Crossman, F., 250.Crone, H. J., 56, 271.Cross, P. C., 39, 179, 197.Crossley, F. S., 229.Crowfoot, (Miss) D. M., 329.Croxall, W. J., 261.Cruickshank, E. M., 400.Cruse, K., 458.Cultrera, R., 74.Cuthbertson, A., 200.Cuthbertson, A. C., 53.Cuthbertson, C., 37.Cuthbertson, D. P., 415.Cuthbertson, M., 37.Cutler, W. O., 294.Cutting, W. C., 422.Dacey, J. R., 46.Dakin, H. D., 312.Dane, (Frl.) E., 241.Dangerfield, W. G., 425.Daniels, F., 66.Danz, W., 35.Darapsky, A., 325.Darrer, E., 259.Darzens, G., 256.Datta, S. C., 42, 43.Davidson, D., 234.Davies, M. M., 54.Davies, W. C., 54.Davis, R.0. E., 168.Davis, T. W., 74, 278.Dawihl, W., 150, 161.Day, J. N. E., 42, 43.Dean, L. A., 472.De Boer, J. H., 158.Debye, P., 76, 85, 88, 89, 170, 171.Dee, P. I., 22.De GuxmQn Carrancio, J., 81.De Hemptinne, M., 214.Deines, 0. von, 434.De Laszlo, H., 210.De Leeuw, A. J., 195.Delbpine, M., 223.Delsasso, L. A., 12, 13, 21, 26.Demant, V., 486.Deming, (Miss) L. S., 180.Dempster, A. J., 8.Denigbs, G., 491.Dennis, L. M., 147.Dennstedt, I., 286.Dent, C. E., 369, 371, 374, 375.Denyes, R. O., 343.De Rassenfosse, A., 168.De Right, R. E., 66, 67.Dersch, F., 245.De Saint-Rat, L., 485.Desnouelle, P., 305, 312, 313, 315.Devonshire, A. F., 36, 80.Dewald, R. H., 479.Dewan, J. G., 420.Dewing, T., 421.Deys, W.B., 449.Deilelid., M., 36, 388.Dhar, J., 203.Dhar, N. R., 66,Dickey, J. B., 244.Dickinson, R. G., 54, 60.Dickinson, S., 311.Diels, W., 366.Dieterich, H., 360.Dietz, E. M., 378, 385.Dietz, J., 213.Dietz, V., 91.Dijkman, M. J., 449.Dimroth, O., 237.Dintzes, A. I., 281.Dischendorfer, O., 339, 340.Discombe, G., 423.Dittler, E., 464, 474.Dixon, B. E., 474, 480.Dixon, J. K., 48, 273.Dixon, K. C., 420.Dobbelstein, O., 285.Doblhammer, F., 361.Dobrovolny, F. J., 343.Dopel, R., 14.Doetsch, J., 458.Dmuvre, J., 230.Dole, M., 32, 33, 48.Dolliver, M. A., 215.Donath, W. F., 352.Donelson, J. G., 96.Dooley, M. D., 271.D’Or, L., 88.Dostal, H., 195.Dougherty, G., 251.Dragan, A., 261.Drew, H.D. K., 145.Dreyer, R. M., 490.Driel, M. van, 167.Drumm, P. J., 405.Drummond, J. C., 411, 413, 414.Du Bridge, L. A., 13.Duckert, R., 486.Duffendack, 0. S., 456,459,461,462.Dufraisse, C., 234, 235, 389, 390, 391,Dull, M. F., 269.Dulon, R., 240.Dunkelberger, T. H., 483.Dunlop, D. M., 417.Dunn, L. R., 469.Dunn, R. T., 259.Dunning, J. R., 23.Dupont, G., 223, 240.Dupont, R., 236, 237.392, 393498 INDEX OF AUTHORS’ NAMES.Durand, H. W., 222.Durland, J. R., 227.Du Vigneaud, V., 323, 324, 325.Duzee, E. M. van, 226.Dwyer, F. P., 485.Dielopov, B. Z., 25.Dziewohski, K., 254.Eaton, J. C., 423.Eaton, J. T., 260.Eberle, H., 248.Ebihara, T., 404.Echols, L. S., 47.Eck, J. C., 389, 409.Eck, R., 313.Edgar, C.E., 404.Edisbwy, J. R., 400.Edwards, T. G., 67.Eegriwe, E., 487, 488.Eekelen, M. van, 406.Eggers, H., 146.Egli, R., 327, 328, 329, 330.Egloff, G., 260.Ehlers, R. W., 95, 101, 102, 103.Ehmann, L., 328, 329, 330, 395.Ehmert, A., 28.Ehrenberg, W., 196.Ehrenfest, P., 27.Ehrenstein, M., 358.Ehrhardt, F., 171.Ehrhart, O., 232.Ehrlich, F., 299.Ehrlich, P., 162.Eistert, B., 263.Elbe, G. von, 48, 49.Eley, D. D., 34, 41.Elle, D., 88.Elliot, N., 163.Ellis, C., 224.Ellis, C. D., 23.Ellis, J. W., 92.Ellison, J. B., 400.Ellman, P., 407.Elmby, A., 408.Elmer, H., 295.Elsmie, G. V., 263.Elson, L. A., 292, 293.Eltekoff, A., 268.Elvehjem, C. A., 403.Embree, N. D., 102, 103, 105.Emelem, H. J., 69.Emerson, G.A., 410.Emerson, K., 422.Emerson, 0. H., 410.Enderlin, L., 389, 390, 392.Endermam, F., 369, 374.Endo, S., 452.Engelder, C. J., 483.Engelhardt, W. von, 479.Epprecht, A,, 37.Erdey-Gfiz, T., 108.Eriksson-Quensel, I. B., 427.Erlenmeyer, A., 234.Erlenmeyer, H., 37, 39, 40, 114.Errera, J., 90, 91.Esau, A., 88.Espenschied, H., 161.ESS, P. R. van, 247.Esterrnann, I., 8, 23.Etienne, A., 391.Eucken, A., 35, 36, 71, 80.Euler, H. von, 402.Evans, H. M., 410.Evans, M. G., 52.Evans, W. C., 239.Evans, W. L., 286, 287, 288.Evering, B. L., 265, 267, 278.Ewell, R. H., 82.Eyring, H., 45, 61, 79, 81, 82, 83.Fairbrother, F., 252.Fairclough, R. A., 54.Faltis, F., 360, 361.Fang, S., 163.Fankuchen, I., 428.Farkas, A., 33, 34, 35, 40, 41, 49.Farkas, L., 34, 41.Farlow, M., 225.Farlow, M.W., 260.Farquharson, J., 137.Farr, ?V. K., 195.Fearon, W. R., 457, 468.Feather, N., 22.Feenberg, E., 9.Feigl, F., 476, 477, 483, 486, $87,Feltham, C. B., 437.Fenger-Eriksen, K., 34.Ferguson, A., 36.Fermi, E., 24.Fernelius, W. C., 248.Fernholz, E., 411.Ferrand, M., 405.Ferrari, A., 168.Ferrari, R., 404.Feussner, O., 459.Fichter, F., 113, 140, 149.Fiedler, H., 343.Fielding, G. H., 278.Fieser, L. F., 201, 219, 391.Filipova, N. S., 34.Finbak, C., 180, 214.Finch, G. I., 199.Findeisen, O., 461.Fink, H., 449.Finkelstein, J., 355, 356, 401.Finn, A. N., 469.Firla, T., 252.Fischer, Hans, 369, 370, 371, 373,374, 375, 376, 377, 378, 379, 380,381, 382, 384, 385, 386, 387.Fischer, Hans (Berlin-Dahlem), 135.Fischer, J., 453.Fischer, W., 147, 269.488INDEX OF AUTHORS’ NAMES. 499Fisher, C.H., 239.Fisher, R. A., 8.Fishgold, H., 74.Fisk, C. F., 61, 66.Fisk, J. B., 22.Fitch, A. A., 461.Fitzgerald, (Miss) M. E., 96.Fleck, E. E., 339.Fleischmann, R., 20.Fleitmann, T., 116.Fletcher, C. 5. M., 47, 277.Fleury, P., 230.Flood, H., 36.Follett, D. H., 462.Foord, S. G., 48, 281.Forbes, G. S., 66, 73, 278.Fordham, J. J., 168.Foresti, B., 223.Fornwalt, H. J., 36.Foster, G. A. H., 421.Foster, G. L., 313.Foster, J. S., 461, 462.Foulis, M. A., 423.Fourneau, E., 421.Fowler, R. H., 44, 84, 90, 173.Fowler, R. M., 481.Fowler, W. A., 12, 13, 14, 21, 26.Fox, J. J., 91.Fox, S.W., 314.Foz, 0. R., 189.Fraenkel-Conrat, H., 310, 326, 356.Frame, G. F., 330.Francis, F., 183.Franck, J., 60, 75.Frank, H. S., 101.Frank, 1. M., 72.Franke, A., 342.Franke, W., 66.Fraser, H. J., 490.Frauendorfer, H., 360.Fred, E. B., 439, 449.Frei, J., 329.French, C. S., 433.Frenkel, J., 83, 154.Freon, A,, 27.Frere, F. J., 476.Frey, C. N., 401.Frey, F. E., 269.Freymann, R., 91.Friedrich, W., 373.Friedrichsen, W., 358.Friend, J. N., 266.Friend, N. A. C., 238, 239, 240.Friess, H., 62.Frisch, 0. R., 23.Frisch, P., 136.Fritz, H., 482.Frivold, 0. E., 39.Fromageot, C., 438, 439.Fromherz, H., 34.Frost, JS A., 272.Frost, A. V., 281.Frost, D. V., 403.Fruton, J. S., 310.Fujita, A., 404.Fuller, A.T., 421, 422.Fulmer, E. I., 443.Funk, C., 403.Funk, I. C., 403.Furry, W. H., 27.Furter, M., 327, 328, 337.Fuson, R. C., 239, 240, 260.Gabbard, J. L., 32.Gabbe, E., 406.Gabriel, S., 390.Gartner, M., 310.Gaerttner, E. R., 12, 13, 26.Gaffron, H., 432, 433.Galfajan, G. T., 469.Gallay, W., 253.Ganguly, P. B., 73.Ganz, E., 90.Gardiner, J. H., 289.Garvey, B. S., 243.Gaskell, T. F., 162.Gattermann, L., 253.Gaunt, W. E., 425.Gavat, I. G., 258.Gay, P. F., 47, 281.Gee, G., 53.Gehrmann, H., 288.Geib, K. H., 41, 273, 281.Geilmann, W., 491.Gelman, S., 422.Gempp, A., 364.Gentner, W., 12, 20.George, S. W., 347.Gercke, A,, 396.Gerding, H., 179.Gerlaoh, E., 90.Gerlaoh, W., 456, 457, 459, 460,Gerlach, Werner, 463.Germain, L., 121.Germer, L.H., 184.Germuth, F. G., 475.Gernea, D., 137.Gershinowitz, H., 46.Ghosh, B., 406.Ghosh, J. C., 72.Ghosh, S. K., 344.Giacomello, G., 327, 338.Giblin, J. C., 488.Gibney, R. B., 33.Gibson, C. S., 145, 168.Gibson, G. E., 21.Gibson, K. E., 66.Gilbert, C. W., 22.Gillam, A. E., 400.Gillespie, B., 40.Gillespie, R. W. H., 440.Gillette, R. H., 90.Gilman, H., 244, 245, 246, 247, 254,260, 261, 392.46500 INDEX OF AUTHORS’ NAMES.Gingrich, N. S., 172.Ginsberg, H., 475.Ginsburg, N., 204.Ginsburg-Karagitscheva, T., 438.Girard, A,, 262.Girard, M., 391.Girard, P., 86, 88.Girard, R., 392, 393.Girardet, A., 357.Glasebrook, A. L., 265, 271.Glasstone, S., 31, 109, 110, 111, 112,Glazebrook, H.H., 57, 265, 266, 269,Gleim, W., 370.Gluckauf, E., 20.Glynn, H. E., 410, 412.Godchot, M., 38, 239.Goebel, S., 378, 379, 385, 386.Goebel, W. F., 296.Gorlich, B., 441.Goldberg, M. W., 329, 330, 331.Goldfarb, I., 261.Goldfinger, G., 74.Goldschmidt, V. M., 459, 464, 473,Goldsworthy, L. J., 349.Gollmick, F., 444.Gomberg, M., 284, 285.GonzBlez, F. G., 293.Goodemoot, K., 261.Goodeve, C. F., 75, 137, 279.Goodson, J. A., 364.Goodwin, T. H., 181, 182.Gordon, R. R., 200.Gordy, W., 92.Gorin, E., 59, 274.Gossner, B., 167.Gossrau, K., 242.Goto, K., 360.Goudsmit, J., 401.Graham, T., 115.Grahame, D. C., 21.Grassmann, W., 357, 358.Grau, E., 488.Gray, A. R., 239, 240.Gray, S. C., 69.Gray, W. H., 421, 422.Green, D. E., 420.Green, L.D., 255.Greenberg, L. D., 408.Greene, C. H., 42.Greenspan, J., 50.Greenstein, J. P., 310.Gregory, R. A,, 71.Gresham, T. L., 215.Grewe, R., 353, 354.Grieneisen, H., 147.Grieve, W. S. M., 284.Griffiths, J. G. A., 61.Grillmayer, H., 339.Grivet, (Mlle.) T., 27.Groag, W., 442.113, 264.270, 277.477, 479.Groenier, W. L., 97.Groggins, P. H., 255.Groll, H. P. A., 248.Gross, A., 396.Gross, O., 88.Gross, P., 33, 51, 282.Gross, P. C., 91.Gross, R. F. J., 112.Grosse, A. V., 260.Groth, W., 67, 75, 282.Grout, F. F., 468.Groves, A. W., 464, 479.Grubitsch, H., 123.Gruner, J. W., 167.Gucker, F. T., 97.Guggenheim, E. A., 44, 46, 98.Guha, A. C., 189.Guha, B. C., 186, 406.Guillemonat , A ., 24 1.Gulbransen, E.A., 97.Gulinova, L. G., 470.Gundermann, J., 195.Guntz, A., 149.Gupta, J., 179.Gupta, N. M., 132.Gurin, S., 352, 353.Gurney, It. W., 32.Gustus, E. L., 332, 340.Guthrie, W. C., 465.Guttmann, R., 299.Guyot, A., 391.Haagen-Smit, A. J., 394.Haberland, H. W., 373.Hackel, W., 89.Hackl, O., 472, 476, 478.Haebler, T. von, 422.Haesler, G., 449.Hafstad, L. R., 11, 12, 14.Hager, F. D., 243.Hahn, O., 16, 17, 21.Halban, H. von, 23.Hale, J. B., 200.Halford, R. S., 54.Hall, N. F., 32, 42.Hall, W. H., 42.Hall, W. T., 491.Haller, A., 391.Halpern, J., 23.Halpern, O., 23, 33.Halse, 0. M., 260.Hamann, K., 379.Hamer, W. J., 96, 103, 104.Hamill, W. H., 34, 38.Hamilton, C. S., 226.Hamilton, T.S., 222.Hammerle, W., 327.Hammett, L. P., 52, 108.Hammick, D. L., 74.Hamonet, J., 231.Hampson, G. C., 145, 168.Hanegraaff, C., 223INDEX OF AUTHORS' NAMES. 501Hanisch, G., 230.Hanson, E. A., 189.Hantzsch, A., 284.Harcourt, G. A., 162.Hardy, R., 182.Harington, C. R., 309, 323.Harkins, W. D., 337.Harkness, J. B., 53, 282.Harms, F., 88.Harned, H. S., 95, 96, 101, 102, 103,104, 105.Harries, C., 249.Harris, L. J., 401, 402, 403, 404, 405,406, 407, 408, 414.Harrison, D. C., 406.Harrison, G. R., 455.Harteck, P., 137, 271, 281, 283.Hartel, H. von, 67.Hartmann, M., 236.Hartung, W. H., 229.Harvey, C. O., 470, 475.Harwood, H. I?., 466, 476, 477, 478,Hashima, H., 299.Haslewood, G. A. D., 261.Hass, H. B., 287.Hassel, O., 39, 180, 214.Hatt, H.H., 239.Hauck, H. M., 406.Haught, J. W., 474.Haurowitz, F., 381.Hawking, F., 425, 426.Haworth, W. N., 294, 297.Hawthorne, J. R., 406.Haxby, R. O., 10.Healey, N., 74.Hecht3 F., 466, 467, 468, 474.Hecker, J. C., 95, 96.Heckmaier, J., 381.Heen, E., 453.Heidt, L. J., 73, 278.Heilbron, I. M., 340, 400.Rein, W., 62.Heinemmn, M., 406.Heisenberg, W., 28.Heitler, W., 26, 27.Helberger, J. H., 374.Helferich, B., 288, 289.Heller, W., 52.Hellmann, H., 77.Hellriegel, W., 236.Helm, D. F., 46.Henderson, W. J., 11.Hendricks, S. B., 91, 160, 167,>168,Henglein, F. A., 300.Hengstenberg, J., 180.Henne, A. L., 207.Henneberg, W., 116.Hennelly, T. J., 426.Henrion, J., 88.Henry, K.M., 410.Henry, T. A., 364.479.180, 202, 211.Hentzschel, W., 397,Henze, M., 240.Hepp, H. J., 269.Herb, R. G., 11.Herbert, J. B. M., 43.Hermance, H. W., 482.Hermann, M., 137.Hermann, S., 441.Hermans, P. H., 195.Herrle, K., 376, 379, 380, 385, 386.Herzberg, G., 197, 199, 279.Herzenberg, J., 394.Herzfeld, K. F., 46, 75, 280.Hess, K., 195, 357.Hesse, G., 220.Hettner, G., 88.Hevesy, G. von, 154, 477.Hewett, C. L., 261.Hey, D. H., 258, 264, 282, 283, 284,285.Hey, M. H., 474.Heydenburg, N. P., 12.Heyes, J., 463.Heyes, R. G., 347.Heymann, K., 285.Heyn, F. A., 17.Heyne, G., 253.Heyrovskf, J., 109.Hibben, J. H., 90.Hickey, F. C., 103.Hickling, A., 108, 1 0, 111, 112, 1Hickman, K. C. D., 221.Hicks, C.S., 358.Hilbert, G. E., 351.Hildebrand, J. H., 31, 81, 173.Hilferding, K., 61.Hill, E. L., 10, 12.3.HHHHHHHHHHHHHHHHHI3HHHHHHH:ill; N. G.', 403.Iillebrand, W. F., 464, 468, 479, 486.Illy, G., 223.Iillyer, J. C., 473.inkel, L. E., 258, 259.:insberg, K., 405.inahelwood, C. N., 44, 47, 54, 55,htermaier, A., 285.inton, H. D., 261.hohata, R., 232.Iirota, K., 33, 40, 41.:irschfelder, J., 79, 83.?schlaff, E., 74, 282..irshberg, Y., 74.:irst, E. L., 297.itchen, C. S., 456.:oare, F. E., 36.:ebbs, B. C., 450.Iockett, R. C., 288.:olemann, P., 35, 39, 114.:onigschmid, O., 146.brghrd, G., 475.:oerlein, H., 422.Iosli, H., 328, 329, 330, 333.:ofeditz, W., 265, 266, 267, 275.58, 276602 XNDEX OF AUTHORS’ NAMES.Hofer, E., 459.Hofer, H., 145, 330.Hofer, J.W., 402.Hoffman, J. I., 469, 472, 475, 476.Hoffmann, A., 260.Hoffmann, E., 358.Hoffmann, J., 74.Hoffmann, J. G., 23.Hoffrnann, R., 67.Hofmann, E., 296.Hofmann, H. J., 371.Hofmann, K., 329, 330, 333, 335.Hofmann, K. A., 232.Hoggan, I. H., 430.Holch, H., 146.Holiday, E. R., 403.Holl, H., 342.Holloway, J. H., 258.Holmes, A., 466.Holmes, H. N., 399.Holscher, F., 368.Holschneider, F. W., 358.Holst, G., 73.Holt, E. V., 478.Holtermann, C., 150.Holtz, (Frl.) J., 243.Holzmiiller, W., 88.Hook, G. R., 481.Hook, H., 236.Hoover, A. A., 411.Hoover, S. R., 452.Hopff, H., 257, 258.Horclois, R., 390.Horeau, A., 223.Horiuti, J., 33, 34, 40, 41, 108.Horkheimer, P., 481.Horn, E., 269.Horner, L., 367, 368.Horrex, C., 52.Horton, A.T., 55.Horton, C. A., 461, 462.Hosemann, R., 195.Hoshi, M., 349.Hoshino, T., 356, 401.Hotchkiss, M., 436.Houben, J., 259.Houk, A. L., 261.Hove, H. van, 285.Howe, J. P., 56.Howell, 0. R., 195.Howell, W. N., 345.Hoye, H. J., 23.Hozacik, A. P., 260.Hromatka, O., 329.Huber, H., 121.Hudson, C. S., 301.Hueber, H., 466, 474.Hiickel, E., 95, 184.Huckel, W., 396.Huffman, J., 34.Huffman, J. R., 42.Huggins, M. L., 89, 161, 181, 213,323.Hughes, E. W., 183.Bugill, J. A. C., 214.Hulla, G., 260.Hurd, C. D., 255, 275.Hurley, F. H., jun., 480.Hurran, W. J., 239.Hurst, D. G., 11, 26.Husemann, E., 53.Husini, K., 20.Huston, R.C., 261.Huyser, H. W., 328.Hyde, J. F., 385.Hynd, A., 290.Hynes, W. A., 484, 491.I. G. Farbenindustrie, 245, 254.Iball, J., 202.Iglauer, A., 442.Imai, T., 354.Inata, R., 360.Ingold, C. K., 41, 42, 43, 200.Innes, J. M., 419.Inouye, J. M., 262.Ionescu, C. N., 252, 256.Ipatiev, V. N., 224, 258, 260.Iredale, T., 66, 67, 279.Irrgang, K., 441.Irvine, J. C., 290.Isticescu, D. A., 252, 257, 258.Ishii, C., 28.Ishiwata! S., 351, 362, 363.Iskendenan, H. P., 36,Isler, O., 341.Ismail, A. M., 479.Itschner, V., 292.Iwasaki, J., 466.Jackson, A,, 195.Jackson, C. A., 474,Jackson, D. A., 8,Jackson, E. L., 301.Jackson, H., 222.Jackson, W. F., 273.Jacob, (Misa) A., 353, 356.Jacob, K. D., 477.Jacobi, G., 75.Jacobs, W.A., 331, 332, 339.Jacquot, J., 445.Jaeger, J. C., 26.Jakob, J., 464.James, F. W., 40.Jancsb, H. von, 424, 425.Jancs6, N. von, 424, 425.Janczak, W., 465.Janke, A., 442.JAnossy, L., 28, 29.Jansen, B. C. P., 362, 401.Jansen, W. H., 463.Jantsch, G., 123.Jawein, L., 117.Jefferson, M. E., 202, 211INDEX OF AUTHORS’ NAMES. 503Jenkins, D. I., 52.Jenkins, F. A,, 43.Jenkins, H. O., 213.Jensen, K. A., 168.Jerzmanowska-Sienkiewiczowa, Z.,Jochem, E., 284.Jockusch, H., 66.Johnson, E. M., 446.Johnson, F. D., 422.Johmon, J., 430.Johnson, K. C., 343.Johnson, M. H., 14, 23.Johnson, R. E., 402.Johnson, W. A., 418.Johnston, H. L., 42.Johnston, W. R., 265, 267.Jois, H. S., 345.J6n&s, J., 486.Jones, F.T., 491.Jones, G., 36.Jones, J. L., 269.Jones, R. N., 222.Jones, T., 40.Jones, T. O., 32, 42.Jordan-Lloyd, D., 323, 326.Jorg, H., 254.Jonssen, W. P., 233, 234.Jorpes, E., 294, 295.Jost, K,, 477.Jost, W., 154, 157.Jouan, R., 35.Jowett, M., 420.Juchum, D., 285.Jungers, J. C., 40, 52, 57, 204, 281.Justi, E., 39, 179.344.Kadiera, K., 361.Kaertkemeyer, L., 68.Kagan, M. J., 234.Kahr, K., 382, 385.Kainrath, P., 344.Kaiser, (Frl.) N., 458.Kajiro, K., 367.Kalckar, F., 13.Kallmann, H., 14.Kamen, M., 16.Kamp, J. van de, 227.Kampfhammer, J., 313.Kandler, L., 108.Kane, G. P., 49.Kane, N. L. R., 52.Kanematu, S., 466.Kannuluik, G. W., 35.Kantor, T., 112.Kantzer, M., 137.Kapadia, M. R., 189.Kapfenberger, W., 129.Kapitza, P., 176.Kappeler, H., 140.Kagustinsky, A.F., 39.Karasima, T., 443.Karimullah, 353.Karlberg, O., 295.Karrer, P., 232, 290, 292, 301, 339,Karrer, W., 339, 401.Kaschtanov, L. I., 253.Kasprzyk, K., 313.Kassel, L. S., 44, 281.Katagiri, H., 440.Katz, S., 46.Katzenstein, (Mlle.), 237.Kauffmann-Cosla, O., 443, 444.Keesom, W. H., 75, 78, 176.Keil, A., 460.Keller, W., 234.Kellermam, H., 376, 377, 379.Kelly, S., 408.Kemp, J. D., 36.Kencaid, J. Y., 79.Kenner, J., 352.Kenny, M., 422, 423.Kerestky, J. C., 353.Kerst, D. W., 11.Keston, A. S., 96.Kesztler, F., 358.Ketelaar, J. A. A., 169, 189.Keutner, E., 88, 89.Khodschaian, S., 62, 64.Kikuchi, S., 20.Kilde, G., 480.Kilpetrick, M., 52.Kimmig, J., 368.Kimpel, W., 350.Kimura, K., 28.Kimura, Y., 349.King, A., 37.King, A.J., 162.King, C. G., 404.King, C. V,, 62.King, F. E., 359.King, H., 313, 360, 361, 399, 424.Kinnersley, H. W., 352.Kinsey, E. L., 92.Kirby, R. H., 246.Kirilov, M. M., 481.Kirkwood, J. G., 77.Kirsanove, V. A., 446.Kistiakowsky, G. B., 46, 53, 200, 215,Kitagawa, S., 330.Kitahara, K., 440.Kitaigorodski, A., 181.Kitasato, Z., 328, 331, 332, 333, 334,335, 337, 360.Klarmann, H., 26.Klasens, H. A., 169.Klaveren, F. W. van, 353.Klein, P., 339.Kleiner, H., 249, 250.Kleiner, I. S., 405.Klekotka, J. F., 469.Klemenc, A,, 112, 149.Klemm, W., 124, 145.411, 435.271, 282504 INDEX OF AUTHORS’ NAMES.Klingelhoefer, W. C., jun., 65.Klit, A., 200.Knight, B.C. J. G., 403.Knight, E. C., 446.Knol, K. S., 14.Knoop, F., 418.Knopf, A., 469.Knorr, C. A., 108.Knorr, H. V., 370.Knorre, G. von, 116.Knowles, H. B., 470.Koblitz, W., 71.Koch, J., 23.Koch, J. A., 253.Koch, P., 470.Kocknitz, A., 329.KOCZY, A., 124.Koelsch, C. F., 389.Koenig, E. W., 473.Koerber, W., 450.Kottig, R., 442.Kotz, A., 235.Koveskuty, J., 425.Kohlbach, D., 351.Kohler, E. P., 389.Kohlrausch, K. W. F., 200.Kokkoros, P., 166.Kolthoff, I. M., 480, 481, 485.Kornarewsky, V. I., 258.Komarovski, A. S., 486.Kon, S. K., 410.Kondakoff, I. L., 256.Kondo, H., 351, 362, 363.Kondrateev, V., 49, 70, 71.Kondrateeva, E., 71.Kondrateeva, H., 49.Konopinski, E. J., 24.Konovalova, R.A., 357.Konstantinova-Schlesinger, M., 74.Kopeloff, L. M., 440.Kopeloff, N., 440.Kopfermann, H., 8.Kopper, H., 39.Kor&nyi, A., 417.Korenman, I. M., 482, 490.Korman, S., 38.Kornfeld, G., 62, 64, 75.Kotake, M., 365, 366.Koteswaram, P., 90.Krafft-Ebing, H., 467.Kraft, L., 231.Kranzlein, G., 251, 262.Krasnovski, 0. V., 471.Kratky, O., 195.Kraus, J. D., 15.Kraus, O., 169.Krause, N. W., 258.Krauskopf, K. B., 64, 67.Krauss, F., 51.Krauss, G., 379.Krauss, w., 47.Krebs, H. A., 417, 418.Kreider, L. C., 288, 298, 301.Sremers, R. E., 394.Irishnan, K. S., 184.<roger, F. A., 39.Crohnke, F., 359, 366.Croepelin, H., 151.(rogh, A., 34, 437.Zroupa, A., 342.Croup&, E., 466.Cruber, O., 329.huger, H., 8.huger, P.G., 22.Cruis, A., 39, 179.< m h o l z , P., 488.grutter, H., 174.Krznarich, P. W., 299.Kubiczek, G., 345.Kubli, U., 401.Kuchler, L., 74, 282.Kuhlewein, M. von, 288.Kuffner, F., 345.Kuhn, E., 14.Kuhn, H., 8, 78, 358.Kuhn, R., 221, 305, 312, 313, 315,353, 399.Kuick, L. F., 225.Kulberg, L. M., 484, 487.Kumler, W. D., 86.Kunne, W. R., 10.Kurschner, K., 441.Kurzen, F., 135.Kuss, E., 132.Laar, J., 162.Laborey, F., 443.Labriola, G., 285.Lachs, H., 36.Laffitte, P., 150.La Forgo, F. B., 290.Laitinen, H. A., 481.Lal, P., 73.Lambert, J. D., 282.La Mer, V. K., 38, 39, 40, 50, 51, 54,94, 96.L a m , O., 304.Lampson, G. W., 22.Landelli, A., 159.Lange, E., 38.Lange, J., 230.Langer, L.M., 24.Langseth, A., 200.Lark-Horovitz, K., 173.Laroux, P., 439.Larsh, T., 35.Lasarev, B. G., 127.Laslett, L. J., 15, 26.Lassettre, E. N., 89.La Touche, C. J., 447.La Tour, F. D., 184.Laudenklos, H., 67, 151, 282.Laue, G., 108.Lauris, A,, 71.Lauritsen, C. C., 12, 13, 14, 21, 26INDEX OF AUTHORS’ NAMES. 505Lautenschlager, W., 387.Lautsch, W., 267, 268, 269, 271, 276,380, 381, 386.Lava, V. G., 439.Lavin, G. I., 273.Lavollay, J., 443.Lawrence, A. S. C., 46.Lawrence, C. A., 257.Lawrence, R. D., 417.Lawson, C. G., 37.Lawson, L. J., 15.Leach, R. H., 128, 146.Lebbink, F. J., 180.Leckie, A. H., 200.Lecoq de Boisbaudran, P. E., 147.L’Ecuyer, P., 359.Leder-Packendorff, L., 222.Lederer, E., 400.Leermakers, J.A., 57, 277, 278, 279.Lehfeldt, W., 154.Lehmann, H., 420.Lehmann, H. L., 61.Leicester, H. M., 330,Leigh-Smith, A., 25.Leighton, P. A., 39, 58, 67, 73, 91,Leitmeier, H., 476.Lejeune, G., 110.Lenel, F. V., 180.Lennard-Jones, J. E., 36, 77, 80, 177.Lennox, F. G., 483.Leo, M., 246.Leong, P. C., 402, 414.Lepkowsky, S., 404.Leprince-Ringuet, L,, 26.Leroy, A. M., 413.Leschhorn, O., 377.Leslie, W. M., 110.Letort, M., 278.Leuchs, H., 366.Leuenberger, H., 327, 328.Leupold, E., 390.Leupold, H., 269.Levanas, L. D., 58, 277.Levene, P. A., 290, 292, 298, 301,Levi, G. R., 164.Levina, S., 107, 109.Levy, H., 214.LBvy, H. A,, 180.Lewis, B., 48, 49, 139.Lewis, D., 481.Lewis, G. N., 8, 43.Lewis, H. K., 132.Lewis, S.J., 458, 464.Lewis, W. B., 14.Libby, W. F., 60.Liddel, U., 91.Lidwell, 0. M., 51.Lieber, E., 223.Liguori, M., 330.Lim, H., 449, 460.Linch, F. W., 246.267, 277.312.Lindner, J., 481.Line, W. R., 470.Lingane, J. J., 481, 485.Link, K. P., 298, 299, 300.Linnett, J. W., 58, 73, 267.Linstead, R. P., 255, 262, 263, 369,371, 372, 373, 374.Liotta, S., 40.Lirmann, J. V., 159.Lister, M. W., 74, 214.Livingston, M. S., 7, 23.Ljung, H. A., 486.Llewellyn, F. J., 181.Locker, T., 278.Lohmann, K., 402, 403.Lohmar, W., 34.Lojkin, M., 429.Loleit, H., 265.Lomax, R., 322.London,Long, E. A,, 36.Long, F. A., 54.Long, P. H., 422.Longsworth, L. G., 37, 39, 440.Lonsdale, (Mrs.) K., 185, 186, 188,212, 372.Loose, L., 451.Lord, R.C., jun., 149, 200.Lorenz, R., 488.Loring, A. D., 174.Loring, H. S., 324, 428, 431.Lothrop, W. C., 219.Lourie, E. M., 399, 424.Loury, M., 391.Lowe, A. R., 369.Lowe, C. S., 487.Lu, G. D., 402.Lubarsky, G. D., 233.Lucas, R., 269.Ludlam, E. B., 61.Ludwig, C., 292.Luttringhaus, A., 247, 342.Lugovkin, B. P., 239, 240.Lund, H., 229.Lunde, G., 453.LundegBrdh, H., 457, 461.Lundell, G. E. F., 464, 468, 469, 472.475, 476, 486.Lundgren, H. P., 307.Lundqvist, D., 162.Lupin, F. von, 231.Luther, R., 67.Lyman, C. M., 24.75, 76, 77, 78, 185.Maass, O., 35, 36.McBain, A. M., 427.McCance, R. A., 415, 416, 417.McConnell, D., 167.McCorkle, M., 261.McCoy, H. N., 129, 131.MacCulloch, A. F., 237.MoCullough, J.D., 160506 INDEX OB AUTHORS’ NAWES.McCutcheon, A., 415.McDonald, R. D., 67.Macdonald, R. T., 8, 43.MacDougall, F. H., 329.Macfarlane, A. S., 307.McGechen, J. F., 260.MacGillavry, D., 34.McGookin, A., 348.McGowan, G. K., 402.Machatschki, F., 161, 165.Machin, J. S., 97,MacInnes, D. A., 39, 103, 105, 107,Mack, E., 46.McKenna, J. F., 261.McKibben, J. L., 11.McKinney, H. H., 431.Mackintosh, J., 410.McLaughlin, R. R., 253.McLennan, J. C., 145.McMillan, E., 16.MacMullen, C. W., 343.McNarnee, R. W., 275.McRae, D. R., 462.Macrae, T. F., 404.Macwalter, R. J., 411.McWaters, L. S., 253.Madden, R. J., 403.Maddrell, R., 116.Madinaveitia, J., 358.Magat, M., 79, 84, 90.Magnm, A,, 35.Maier, K., 348.Malaprade, L., 230.Malkin, T., 183.Malko, M.G., 491.Malsch, J., 88.Mamaschlisow, V. I., 20.Manceau, P., 404.Mandryk, G. T., 239.Manjunath, B. L., 345.Mankopff, R., 460.Manley, J. H., 8, 23.Mann, D. W., 272.Mann, F. G., 169.Mann, W. B., 11.Margenau, H., 77.Marie, C., 110.Mark, H., 178, 189, 191, 195, 300.Marrack, J. R., 408.Marsh, J. K., 130.Marshall, E. K., 422.Marshall, J. R., 222.Martin, A. E., 91.Martin, E. L., 391.Martin, G., 88.Martin, L. F., 253.Martin, W., 38.Martin, W. F., 358.Martini, A., 491.Martini, H., 136.Martius, C., 418.Marvel, C. S., 222, 243, 389,440.Masing, G., 108.Mason, C. W., 491.Massoy, H. S. W., 22.Massini, P., 148.Masson, J. I. O., 139.Matheson, H., 42.Mathieson, I., 153.Mathing, W., 152.Matignon, C., 129.Mattauch, J., 8.Matthews, F.E., 249.Matuszeski, J. F., 239.Mauguin, C., 199.Maxted, E. B., 35.Maxwell, L. R., 180, 211.May, A., 350.May, 0. E., 446.Mayer, J., 290, 292.Mayer, J. E., 77, 78.Mead, T. H., 323.Meara, M. L., 183.Mears, W. H., 53, 282.Mecke, R., 271, 274.Medvedev, S., 250.Meer, N., 67.Meerwein, H., 228, 229, 251.Megaw, H. D., 35, 89, 177.Meiklejohn, A. P., 401.Meisel, K., 124, 162.Meissner, M., 58.Meitner, L., 16, 17.Mellanby, E., 400.Mellon, M. G., 477.Mellor, D. P., 168.Mellor, J. W., 153.Melville, H. W., 34, 49, 68, 69, 70,Melville, J., 394.Menschikov, G., 350.Mentzer, C., 405.Menael, H., 480.Menzel, W., 136.Monzies, A. W. C., 36, 38.Mesha, A., 477.Messiner-Klebermass, L., 293.Messonshnik, S.S., 491.Metcalf, T. P., 350, 365.Moth, H., 377.Metzger, W., 373.Meunier, P., 404.Meuwissen, T., 405.Meyer, C. E., 312.Meyer, G., 28.Meyer, H., 451.Meyer, H. H., 173.Moyer, J., 327.Meyer, K., 234.Meyer, Karl, 296.Meyer, K. H., 189, 191, 193, 194, 300.Michael, A., 268.Micheel, F., 350.Midgley, T., jun., 207.Mika, J., 468.71, 75INDEX OF AUTHORS’ NAMES. 607Mikeska, L. A., 222.Milas, N. A., 233, 234, 235.Milbourn, M., 456, 458.Miles, F. T., 36, 38.Miller, (Miss) C. C., 465, 473.Miller, E. J., 297.Miller, E. P., 173.Miller, J. F., 487.Miller, O., 237.Miller, W. A., 137.Miller, W. S., 162.Milligan, C. H., 261.Millikan, R. A., 27.Millman, S., 8.Millon, N.A. E., 137.Mills, A. G., 279.Mills, W. H., 219.Milone, M., 189.Minder, W., 168.Minkow, I., 36.Mirsky, A. E., 308, 323.Misch, L., 194.Mitchell, A. C. G., 25.Mitchell, D. R., 255.Mitchell, J. S., 53, 74.Mitchell, J. W., 58.Mitchell, N. W., 243.Mitchell, R. L,, 457.Mitchell, W., 358.Mitsuwa, T., 365, 366.Mitter, P. C., 263.Mizushima, S., 92.Moller, E. F., 222.Morgeli, E., 329.Moerman, N. F., 179, 183.Moffet, G. L., 340.Moke, C. B., 470.Mollet, P., 91.Molvig, H., 370, 388.MonadjBmi, M., 26.Monkman, R. J., 145.Monti, A., 435.Moon, C. H., 35.Moonik, W., 346.Moore, T., 400.Moran, C., 90.Morell, S., 298, 299.Morey, G. W., 174.Morgan, (Sir) G. T., 237, 474.Morgan, S. O., 184.Morgan, W. H., 259.Morgan, W.M., 359.Morgan, W. T. J., 292, 293.Mori, K., 365.Morikawa, K., 40, 41, 49, 68, 69, 70.Morino, Y., 92.Morita, N., 32, 42.Moritz, H., 464.Morley, J. F., 238, 239.Morningstar, O., 174.Morrell, W. E., 173.Morris, C. J. U. R., 399.Morris, H. J., 452.Morse, P. M., 22.Mortensen, R. A., 73, 267.Morton, A. A., 245.Morton, R. A., 400.Moseley, V. L., 211.Moser, L., 475.Mosettig, E., 227.Mosset, M., 66.Moulds, L. de V., 239.Moureu, C., 234, 235, 390.Moyer, A. T., 446.Moyer, W. W,, 380, 388.Muller, Adolf, 196, 371, 373.Nuller, Alex., 77, 184.Mueller, D. W., 22.Muller, E., 110.Muller, F. H., 85.Mueller, J. H., 403.Muller, K., 377.Muller, K. L., 66.Muller, R., 240.Muller, G. J., 39.Muller-Skjold, F., 75.Mumm, O., 358.Munch, R.H., 75.Mund, W., 68.Munro, H. N., 415.Murgatroyd, F., 424, 425.Murphy, R. K., 485.Musulin, R. R., 404.Muthmann, W., 145.Nagahara, T., 466.Nagel, R. H., 255.Naherniac, A., 92.Nakamura, H., 433.Nakanishi, S., 394.Nalbandjan, A,, 49.Narang, K. S., 348.Naray-Szabo, S. von, 108, 109.Nasu, N., 150.Natelson, S., 261.Neddermeyer, S., 28.Needham, D. M., 420.Needham, J., 420.Neher, H. V., 27.Nehlep, G., 154.Nehra, V., 36.Nellis, J., 350.Nelson, A. I?., 66.Nelson, R. E., 66.Nenitzescu, C. D., 252, 253, 256, 257,Neuberg, C., 292, 296.Neuberger, A., 309.Neuhausser, A., 461.Neujmin, G., 267.Neujmin, H., 73, 74.Neuman, M:B., 49.Neumayer, K., 475.Neumayr, S., 146.Neuschul, P., 441.258, 261508 INDEX OF AUTHORS’ NAMES.Newman, A.C. C., 239.Newson, H. W., 14.Newton, R. F., 79, 96.Nicolaysen, R., 410.Niel, C. €3. van, 436.Nielsen, J. R., 163.Niemann, C., 299, 314, 315, 316, 320,Nier, A. O., 8.Nies, N. P., 60.Nieuwenberg, C. J. van, 479.Nieuwenkamp, W., 16 1.Nieuwland, J. A., 261.Niggli, P., 164.Nilakantan, P., 195.Nilsen, K. W., 108.Nims, L. F., 103.Nishida, K., 299.Nishina, Y., 28.Nitka, H., 39, 179.Nitta, I., 39, 180, 183, 189.Nitfi, F., 421.Nixon, I. G., 219.Noble, E. G., 255, 372, 374.Noddack, W., 128.Nolan, E. J., 476.Noll, W., 478.Noller, C. R., 253, 255.Norkina, S., 357.Norris, J. F., 256.Norrish, R. G. W., 48, 55, 56, 57, 61,62, 63, 64, 67, 71, 74, 270, 271,274, 276, 277, 281, 282, 283.Northrop, J.H., 319.Nothdurft, W., 35.Novkk, J., 39, 109.Nowiiiski, W. W., 420.Noyens, E., 405.Noyes, W. A., jun., 56, 61, 66, 74.Nozaki, H., 360.Nussle, W., 236.Nylen, P., 118.326.Ochiai, E., 330.O’Conor, J. S., 24.Oddo, G., 179.Ode, W. H., 469.oy, E., 453.Ogden, G., 110.Ogg, R. A., jun., 269.Ogston, A. G., 307.O’Hara, P. H., 406,Ohdake, S., 355.Ohlinger, H., 248.Ohta, M., 356, 401.Okahara, K., 345.Okamoto, G., 33, 34, 40, 41.Oldenberg, O., 112, 272.Olivier, S. C. J., 253.Olson, A. R., 54.O’Meara, R. A. Q., 421.Onsager, L., 86.Openshaw, H. T., 365, 368.Oppenauer, R. V., 230.Oppenheimer, J. R., 13, 26.Or&hov, A. P., 357.Orla-Jensen, S., 440.Orlov, N. N., 260.Om, J.B., 408.Orr, W. J. C., 35, 40, 51.Orth, H., 369.Osnizkaja, L. K., 447.Otterbein, G., 88.Owen, B. B., 99, 103.Owen, M., 145.Owens, J. S., 459.Oxford, A. E., 450.Ozaki, G., 295.Packendorff, K., 232.Padelt, E., 137.Paden, J. H., 227.Pagel, H. A., 66.Pahlavouni, (Mme.), 237.Pajeau, R., 254.Palacios, J., 189.Palmer, J. W., 296.Palmer, K. J., 210.Paneth, F. A., 20, 265, 266, 267, 268,Pappenheimer, A. M., jun., 439.Parker, E. A., 195.Parks, W. G., 96.Parlee, N. A. D., 46.Parravano, N., 121.Partington, J. R., 37, 39, 121.Partridge, H. M., 131.Pascal, P., 117.Patat, F., 57, 71, 74, 197, 199, 267.Paterson, W. Y., 430.Paton, J. R. J., 423.Patterson, W. H., 35.Paul, R., 223.Pauling, L., 91, 130, 163, 166, 177,185, 196, 199, 209, 213, 219, 308,323, 383.Pauly, H., 292.Paxton, H.C., 24.Pearce, D. W., 122.Pearsall, W. H., 451.269, 271, 275, 276.278, 279, 281.Pearson, T. G., 67, 264,265,266, 267,Pease, R. N., 47.269, 270, 272, 273, 276, 277.Peat, -S., 294:Pedersen, K. J., 50.Pedersen, K. O., 307.Peermohamed, B. H.., 189.Pegram, G. B., 34.Peierls, R., 20.Penney, W. G., 177, 199, 204.Percival, J. O., 54.Perkin, W. H., sun., 249.Perkins, G. W., 236INDEX OF AUTHORS’ NAMES. 509Perlinghi, S. L. T., 214.Pernert, J. C., 284.Perperot, H., 34, 37.Perret, H., 230.Perrier, G., 251.Perrott, G. St. J., 93.Peters, C., 460, 477, 479.Peters, K., 34.Peters, R. A., 352, 353, 402, 403, 420.Petersen, H., 175.Petersen, M., 150.Peterson, W.H., 439, 440, 449.Petre, A. W., 427.Petri, H., 247.Petrova, A., 74.Peyronel, G., 164.Pfaehler, K., 301.Pfau, A. S., 393, 394, 396.Pfeifer, P., 291, 312.Pfeiffer, M., 328.P k c h k e , J., 300.Pfluger, H. L., 52.Phillips, N. W. F., 40, 281.Philpot, J. St. L., 308.Piantanida, M., 263.Pickard, (Sir) R. H., 237.Pickett, L. W., 203.Pieroh, K., 341.Pieth, P., 328, 337, 395.Pilch, K., 53.Pilgrim, A., 239.PiAa de Rubies, S., 458.Pinck, L. A., 351.Pinnow, P., 180.Piper, S. H., 183.Piret, E. L., 439.Pirie, N. W., 428, 431.Pirschle, K., 445.Pitzer, K. S., 106.Piutti, P., 239.Piezolato, P., 253.Placzek, G., 20.Plant, S. G. P., 255.Plantanida, M., 351.Platt, B. S., 402.Plattner, P. A., 393, 394, 396.Platz, H., 74.Ploeg, W., 255.Plyler, E.K., 92.Pohl, R. W., 75, 158.Polanyi, M., 41, 44, 52, 67, 108, 269.Policard, A. A., 404.Pollak, O., 339.Pollard, E., 10.Poller, K., 254.Polson, A. G., 304.Poluektov, N. S., 485, 486.Ponndorf, W., 228, 229.Pontalti, S., 393.Pool, M. L., 17.Popov, B., 70, 74.Popp, L., 39.Poppe, G., 37.Popper, E., 285.Porret, D., 73, 279.Porter, C. W., 54.Porter, J. M., 67.Postovski, J. J., 239, 240.Potakempo, G., 89.Potts, J. C., 62, 65.Powell, H. M., 145, 168.Powers, P. N., 23.Prandtl, W., 131.Prasad, M., 189.PrAt, S., 483.Pratt, N. H., 146.Pray, H. A. H., 283.Prelog, V., 263, 350, 361.Prentiss, S. S., 99, 100.Preston, R. D., 453.Price, (Miss) G. M., 244.Price, J. R., 349.Prileshajeva, N., 57, 73, 267.Prill, E.A., 449.Prins, J. A., 171, 172, 175.Proom, H., 422.Pruckner, (Frl.) F., 374, 385, 388.Pryde, J., 297.Przylecki, S. J. von, 313.Pugh, W., 147.Pummerer, R., 242.Purcell, R. H., 57, 265, 272, 276.Purdie, A. W., 422, 423.Purdie, D., 169.Purkis, C. H., 74.Pyke, M. A., 401.Quarfaroli, A., 52.Quastel, J. H., 419, 420, 426.Quodling, F. M., 168.Qureshi, M., 36.Rebiiiovitsch, E., 46, 59, 60, 61, 62.Rachele, J. R., 484.Raeder, M. G., 108.Raisin, C. G., 200.Reistrick, H., 449, 450.Rajmann, E., 477.Ramage, H., 457.Raman, (Sir) C. V., 184.Ramm, W., 89.Ramsperger, H. C., 278.Randall, J. T., 169, 171, 172, 173,Randall, M., 97.Raney, M., 222.Rank, I3., 231.Rao, I. R., 90.Raper, R., 359.Rautenstrauch, C., 241.Rawlins, T.E., 427.Ray, J. N., 348.Ray, R. C., 132, 133.Ray, S. N., 404, 408.174510 INDEX OF AUTEORS' NAMES.Ray, W. A., 36.Raymond, E., 234.Rebay, A. von, 374.Redlich, O., 36, 104.Redmond, J. C., 470.Reed, F. P., 348.Regnault, P., 43.Rehaag, H., 148.Reich-Rohrwig, W., 466.Reichstein, T., 255, 343, 396.Reid, E. a., 261.Reiniicker, G., 138, 480.Reindel, W., 242.Reiner, L., 425.Reinhold, B., €12.Reitz, O., 41, 51.Renn, C. E., 436.Renoll, M. W., 207.Retger, L. F., 440.Reuter, F., 450.Rey, M., 482.Reyerson, L. H., 40.Reynolds, D. S., 477.Reynolds, (Miss) T. M., 365.Riblett, E. W., 278.Rice, A. C., 486.Rice, F. O., 46, 264, 205, 267, 271,Rice, K. K., 264.Rice, 0.K., 81, 84, 278.Richardson, F. D., 137.Richardson, H. 0. W., 25.Richardson, T., 352.Richmond, J. H., 263.Richter, C., 463.Richter, D., 234.Richter, H. J., 389.Richter, K., 235.Riddell, W. A., 253.Rideal, E. K., 34,53,74, 107,265,271.Ridenour, L. N., 11.Ridgion, J. M., 239.Rieche, A., 233.Riedl, E., 460, 463.Ries, H. E., 337.Riesenfeld, E. H., 33, 34, 36, 112.Rigamonti, R., 168.R!ley, H. L., 238, 239, 240, 242.Rmehart, J. F., 408.Rinke, H., 290.Rinkes, J., 343.Rippel, A., 443, 444.Ritchie, M., 61, 62, 63, 64.Ritchie, W. H., 352.Rim 9 Miro, 112.Rivin, M., 49.Rizek, A., 351.Roberts, E. J., 103.Roberts, I., 52.Roberts, R. B., 14.Robertson, A., 345, 346, 347, 348.Robertson, J. M., €77, 178, 186, $98,199,201, 202, 20.3, 214, 371, 372.278, 280.Robinson, A.L., 97, 100, 101.Robinson, P. L., 286,Robinson, R., 239, 305, 343, 349, 352,Robinson, R. A., 37, 99.Robitschek, J., 472.Roche, E., 304.Rodd, E. H., 245.Rodebush, W. H., 65, 89, 91, 112,213, 272, 273, 274.Rodionova, K., 438.Roedemr, E., 283.Roelofsen, P. A., 433.Rogers, A. O., 66.Rojahn, C. A,, 483.Rokusho, B., 442.Rollefson, G. K., 47, 58, 60, 61, 62,Rollier, M. A., 159.Romanjuk, A. N., 485.Romeyn, El., 215.Rompe, R., 61.Roof, J. G., 58, 274, 277, 278.Rooksby, H. P., 173, 174.Rosanova, V., 400.Roscoe, M. H., 415.Rose, H., 116, 339.Rose, M. E., 9, 25.Rose, W. C., 311, 312.Rosenfeld, B., 442.Rosenheim, O., 239.Rosenmund, H. W., 2%.Rosenthaler, L., 490.Ross, A.F., 429.ROSS, H. L., 470.Ross, K., 439.Ross, W. F., 271, 324.Rossini, F. D., 97, 217.Rothemund, P., 370.Rowe, R. D., 58, 277.Rowledge, H. P., 471.Roxburgh, H. L., 69, 71.Roy, B. B., 72.Roy, B. S., 348.Royen, P., 153.Ruben, S., 16.Rubin, L. C., 278.Rubin, T. R., 97.Rudolph, E. A., 394,Rudorfer, H., 53,Ruff, O., 136.Ruhemann, S., 394.Ruhkopf, H., 352.Ruhoff, J. R., 215.Rule, A. E., 353, 355.Rumbaugh, L. H., 11, 14.Ruschmann, W., 134.Rushby, G. L., 348.Rushton, J. H., 52.Rusinov, L. I., 20.Russell, A. D., 349.Rustad, S., 39.Ruthardt, K., 459.354, 357, 365, 368, 450.64, 65, 66, 67, 277, 278INDEX OF AUTHORS’ NAMES. 51 1Rutherford, (Lord), 42.Ruzicka, L., 327, 328, 329, 330, 331,333, 334, 335, 337, 338, 340, 341,393, 394, 395.Sachssc, H., 278, 281.Sadovnikov, P., 49.Sagaidak, A.N., 20.Sagel, H., 258.Saini, H., 39.Saigh, G., 272.Sain, A. K., 441.Salmon-Legagneur, F., 269.Salomon, H., 41 1.Saltmarsh, (Miss) 0. D., 56, 270,271,Sandell, E. B., 477, 479.Sandulesco, G., 262.Saposhnikov, D. I., 433, 434.Saracini, M., 47.Sannski, V., 107.Sarkar, A. K., 253.Sartori, G., 35.Sauer, H., 339.Sauer, J., 227.Sauter, E., 190, 191, 195.Sawyer, R. A., 9.Scarborough, H., 405.Scatchard, G., 98, 99, 100.Schacherl, F., 34, 37.Schlifer, K., 35, 36.Schiifer, O., 243, 250.Schafer, W., 250.SchiiLffner, H., 309.Schdanov, H. S., 159.Scheibe, G., 279, 460.Scheiner, K., 131.Schellenberg, 328, 329, 331, 337, 340.Schemjakin, F.M., 487.Schenk, F., 409.Schenk, P. W., 64, 74, 148.Schern, K., 424.Schicke, W., 333.Schiel, J., 137.Schiff, L. I., 14, 22, 23.Schiller, W. J., 483.Schlliger, J., 344.Schlapfer, P., 394.Schleich, H., 290.Schleicher, A., 458.Schlemmer, F., 364.Schlenck, G., 364.Schlenk, W., 243, 249.Schlesinger, H. I., 151.Schlubach, H. H., 243.Schmeisser, M., 139.Schmelzer, C., 88.Schmidlin, J., 148.Schmidt, C. L. A., 313.Schmidt, H. F., 343,Schmidt, M., 449.Scbmidt, O., 231.277.Schmidt, R., 228.Schmitt, J., 241.Schmitz, A., 296.Schmitz-Dumont, O., 379.Schneider, E., 436.Schneider, F., 465.Schneider, G. G., 300, 301Schneider, O., 232.Schnell, B., 243.Schnitxspahn, L., 396.Schnurr, W., 254.Schoeller, W.R., 491.Schon, K., 390.Schoenauer, W., 39, 40, 114.Schoenheimer, R., 262.Schoklitsch, K., 469, 470, 472.Scholes, S. R., 163.Schopfer, W. H., 401.Schoppe, R., 211.Schopper, E., 28.Schossberger, F., 178.Schottky, W., 154.Schreck, C., 88.Schrenk, W. T., 469.Schreyegg, H., 449.Schriel, M., 150.Schroer, E., 488.Schroeter, G., 252, 391.Schrater, K., 150, 161.Schubert, H., 458.Schubnikov, L. V., 127.Schiitze, W., 8, 43.Schulman, J. H., 53.Schultz, A., 401.Schultz, H. L., 10.Schultzer, P., 406.Schulz, F. N., 296.Schulz, G. V., 53.Schulz, L., 236.Schulze, H., 341.Schumacher, H. J., 66, 70, 71, 72,136, 138, 139.Schumb, W. C., 476.Schumm, P., 236.Schuster, A., 137.Schuster, P., 402, 403.Schwab, G.M., 62.Schwartz, E., 108.Schwartz, I?., 121.Schwartz, W., 449.Schwarz, R., 139.Schwarzenbach, G., 38, 40.Schweitzer, E., 456.Schweizer, R., 237.Schwenk, E., 239, 24-0.Schwentker, F. F., 422.Schwinger, J., 22.Sclar, M., 52.Scorn&, A., 179.Scott, D. A., 294.Scott, M., 486, 490.Scott, R. B., 35.Seaborg, G. T., 21512 INDEX OF AUTHORS’ NAMES.Sebba, I?., 147.Seefried, H., 285.Seely, S., 14.Seemann, C. von, 370.Sehl, F. W., 470.Seiberth, M., 236.Seidel, C. F., 328.Seidell, A., 352.Seijo, E., 352.Seith, W., 459, 460.Selby, W. M., 244, 246.Seljakov, N. J., 178.Selvig, W. A., 469.Selwood, P. W., 122.Semenoff, N., 48.Semenova, N., 49.Senftleben, H., 62.Serber, R., 13.Serebriani, S. B., 484.Shankar, J., 189.Share, S., 22.Sharkova, V.R., 281.Shaw, A., 469.Shearman, R. W., 38.Shedlovsky, T., 105.Sheldon, J. H., 457.Sheldon, W., 457.Shepherd, W. G., 10.Sherko, A. V., 281.Sherman, A., 40, 90.Sherman, J., 166, 219.Sherndal, A. E., 394.Sherr, R., 34.Shibata, K., 310.Shioiri, M., 466.Shirahama, K., 453.Shishidi, H., 360.Shoesmith, J. B., 260.Shore, A., 315.Short, O., 100.Shorter, A. J., 145, 168.Shoupp, W. E., 22.Shrawder, J., 96.Shriner, R. L., 221.Shukovskaja, S. S., 470.Shurbagy, M. R. el, 183.Sickman, D. V., 73, 278, 279.Sidgwick, N. V., 177, 213, 219.Siedler, V., 442.Sieverts, A., 35.Sifferd, R. H., 324.Signaigo, F., 225.Silberfarb, M., 109.Silbermann, H., 328.Simmons, N. L., 69.Sirnomum, M., 449.Simon, F., 35, 78, 83.Simons, J.H., 269, 275.Simons, L., 26.Simonsen, J. L., 239.Simpkins, G. W., 400.Simpson, 0. C., 8, 23.Simpson, S . G., 476.Sinclair, D. A., 99.Singer, E., 411.Sinha, K. L., 189.Sirkar, S. C., 179.Siskin, M., 70.Sisson, W. A., 105.Skalla, N., 123.Skjulstad, T., 39.Skraup, S., 254.Slater, J. C., 77.Slavin, M., 461.Slavina, O., 445.Slotte, K. A., 222.Sluckaja, M. M., 34.Small, P. A., 40.Smekal, A., 154.Smethurst, A. F., 474.Smirnov, V., 471.Smith, A. F., 195.Smith, A. M., 430.Smith, D. M., 456, 464.Smith, E. L., 409.Smith, E. R., 34, 42.Smith, G., 450.Smith, G. B. L., 223.Smith, G. Frederick, 480.Smith, Gilbert F., 50.Smith, H. A., 215.Smith, H. G., 394.Smith, J.C., 222.Smith, J. H. C., 436.Smith, L. H., 343.Smith, L. I., 329, 343.Smith, (Miss) M. C., 50.Smith, M. J., 352.Smith, P. K., 103.Smith, R. A., 261.Smith, S., 421.Smith, W., 61.Smith, W. R., 46.Smith, W. W., 438.Smits, A., 39, 179.Smita, B. L., 443, 448.Smoledski, K., 298.Smyth, C. P., 84, 85, 184.Smyth, E. M., 296.Smythe, W. R., 43.Snell, A. H., 11.Snell, E. E., 440.Snoek, J. L., 86.Snog-Kjaer, A., 440.Sokolik, A., 49.Solmssen, U., 435.Solodar, L. S., 260.Solomon, A. K., 200.Solomon, W., 364.Someren, E. H. S. van, 456.Sonderhuff, R., 34.Sone, C., 331, 332, 337.Sonnenfeld, E., 235.SouIe, B. A., 471.Sowa, F. J., 261.Spiith, E., 329,344,346,346,358,364INDEX OF AU’IXORS’ NAMES. 513Spealman, M.L., 273.Specht, F., 476.Spees, A. H., 23.Speitmann, M., 377.Spence, R., 56, 67, 270, 275, 279, 280.Spencer, J. F., 36, 244.Spielberger, G.; 385.Spikes, W. F., 484, 491.Spinks, J. W. T., 67, 199.Spirer, J., 254.Sponsler, 0. L., 190.Spoor, N. L., 40.Sprague, J. M., 226.Spring, F. S., 255, 328, 337, 339,Springall, H. D., 213, 219.Squire, G. V. V., 61, 63.Srinivasan, M., 405.Stadler, O., 394.Stadnikov, G. L., 261.Stallrnann, F. W., 22.Stamm, H., 242.Stange, M., 121.Stanger, H., 232.Stanley, W. M., 426, 427, 428, 429,Stare, F. J., 417.Starkey, R. L., 434, 435.Statham, F. S., 352.Staudinger, H., 195.Stauffer, C. H., 46.Staveley, L. A. K., 47, 55, 276.Steacie, C. W. R., 40, 46, 49, 267, 278,Stearn, A.E., 45.Steele, B. D., 253.Steele, (Miss) C. C., 375.Stehn, J. R., 22.Steiger, B., 483.Stein, B., 330.Stein, G., 327.Stein, O., 358.Steinberg, R. A., 444.Steiner, A. B., 67.Steiner, H., 51.Steiner, W., 61, 62, 273.Steinhardt , J., ’ 53.Steinkopf, W., 343.Stephan, (Miss) D., 67, 279.Stephens, H. N., 234, 235.Stephenson, D., 421, 422.Stern, A., 370, 374, 385, 388.Stern, K. G., 402.Stern, O., 8, 23.Stevens, J. R., 245.Stevens, R. E., 473, 476.Stevenson, D., 83.Stevenson, E. C., 28.Stevinson, M. R., 226.Stewart, C. P., 405.Stewart, F. B., 273.Stewart, G. W., 172.Stewart, K., 69.340.431, 432.281.REP.-VOL. XXXN.Stewart, T. D., 66.Stirton, A. J., 255.Stock, A., 132, 135, 150, 151, 152.Stoddart, E.M., 266, 273.Stone, R. W., 438.Storch, H. H., 281.Storks, L. H., 184.Strain, C. V., 13.Strain, H. H., 263.Strassmann, F., 16.Strating, J., 242.Stratton, (Mrs.) K., 37.Street, J. C., 28.Strickler, H. W., 261.Strock, L. W., 459, 460.Strong, F. M., 403, 449.Strunz, H., 164, 166.Stuart, A., 346.Sturdivant, J. H., 169.Sturm, K., 344.Stursa, F., 246.Style, D. W. G,, 56, 71, 270.Subramaniam, T. S., 346.Suenaga, K., 39, 180.Suess, H., 51, 53, 282.Sutterlin, W., 135.Sundhoff, D., 72.Surdin, M., 79, 84.Suschkevitsch, T., 70.Susemihl, W., 236.Suszko, J., 365.Sutherland, G. B. €3. M., 206.Sutherland, R. O., 103.Sutton, L. E., 214, 219.Svedberg, T., 304, 307, 427.Swings, P., 464.Szalay, A., 10.Szebellhdy, L., 486, 488.Szelag, F., 365.Szent-Gyorgyi, A., 416, 417, 419.Tabuteau, J., 240.Taconis, K.W., 176.Tadokoro, T., 448.Takahashi, T., 441.Takahashi, W. N., 427.Tammann, G., 117.Tamura, M., 63.Tanaka, S., 110.Tananaev, N. A., 485.Tanay, S., 488.Tarajan, W. M., 469.Tarasov, L. P., 173.Tarassova, E. M., 257.Tasker, H. S., 168.Tate, J. T., 12.Tatum, E. L., 439, 440.Taube, H., 67.Tauber, R., 405.Taufel, K., 449.Taylor, A. A,, 278.Taylor, H. A., 74, 278.514 INDEX OF AUTHORS' NAMES.Taylor, H. S., 35, 40, 41, 49, 57, 59,Taylor, L. F., 476.Taylor, T. I., 43.Taylor, W. H., 184.Teare, J. W., 96.Teller, E., 22, 200.Tenenbaum, D., 343.Terenin, A., 57, 59, 73, 267.Terpstra, P., 167, 169.Terrey, H., 128, 129, 131, 146.Theobald, L.S., 477.Thielmann, F., 243.Thillot, A., 117.Thomas, B. H., 409.Thomas, H., 34.Thomas, H. C., 96, 100.Thomer, G., 199.Thompson, H. W., 58, 73, 74, 267.Thompson, J. W., 200.Thompson, R. H. S., 402.Thompson, S. O., 485, 490.Thomson, T. A., 483.Thornberry, H., 429.Thornton, R. L., 15, 17.Thorpe, J. F., 248.Thurnwald, H., 465.Tietz, E. L., 234.Tiggelen, A. van, 68.Timmermans, J., 36, 37.Tippetts, E. A., 96.Tischtschenko, W. E., 228.Titani, T., 32, 42, 280.Todd, A. R., 353, 354, 355, 356, 401,Todd, F. A., 137.Todd, J., 349.Toennies, G., 149, 236.Tolman, R. C., 47.Tomimura, K., 362.Tomita, M., 362.Tomlinson, (Miss) M. L., 353, 354.Torres, R. T., 293.Torrey, K. C., 8, 35.Towndrow, R.P., 39.Townend, D. T. A., 49.Trautmann, G., 409.Travers, M. W., 47, 132, 281.Traves, (Miss) F., 473.Treadwell, F. P., 491.Trefouel, J., 421.TrBfouel, (Mme.) J., 421.Treibs, W., 237, 394.Treje, R., 466.Trenner, N. R., 34, 35, 40, 49, 69Trew, (Miss) V. C. G., 36.Trier, E., 405.Troger, E., 464.Trombe, F., 127, 145.Tronstad, L., 36.Truchet, R., 241.Truffault, R., 223.68, 69, 70, 93, 273, 274, 281.411.70.h o g , E., 472.Csatsas, T., 285.rschelincev, V. V., 184.lbcherni, A. T., 471.rscherning, K., 230.Pschesche, R., 352, 353, 355.rschesnokov, V. A., 434.t!schirch, E., 481.rschopp, W., 404.rseng, K., 349.buds, K., 330.ruck, J. L., 34.rureck, H. E., 100.Furin, J. J., 26.rurkevich, J., 177.ruve, M. A., 12, 14.rwigg, G.H., 34.Twyman, F., 456, 459, 461.Twyman, J. H., 463.Tyson, J. J., 168.Ubbelohde, A. R., 177, 214.Uehara, Y., 92.Uemm,a,, Y., 28.Uhlenbeck, G. E., 24.Ulich, H., 253.Unger, F., 252, 256.Unterkofler, L. A., 443.Urbain, G., 145.Urey, H. C., 34, 42, 43, 273.Urion, E., 241.Urmston, J., 61.Ussing, H., 34.Uyeo, S., 351, 362.Vaisfeld, P. G., 260.Vallarta, M. S., 29.Van Cleave, A. B., 35.Vantu, G. G., 256.Varvoglis, G., 285.Vassiliev, G. M., 443.Vaughan, W. E., 215.Vaughan-Jackson, M. W., 61.Vaux, G., 161.Veen, A. G. van, 327.Veldkamp, J., 14.Velluz, L., 391.Vereschtschagin, L. F., 127.Verleger, H., 197, 199.Verley, A., 228, 229.Verweel, H. J., 167.Vesel3, V., 246.Vesterberg, A., 339, 340, 341.Vestin, R., 402.Vetter, H., 353, 390.Vialard-Goudou, A., 405.Vickerstaff, T., 255, 328, 339.Vickery, H.B., 314, 315.Vierhapper, F., 345.Villiger, V., 242.Vinson, C. G., 427, 429INDEX OF AUTHORS' NAMES. 515Vleck, 5. H. van, 126.Vogel, E., 151.Vogel, H. U. von, 124.Volkenstein, M. V., 92.Volmer, M., 109.Vonnegut, B., 178.Vorhees, V., 221.Vorliinder, D., 242.Voskuyl, R. J., 42.Voss, W., 300, 339.Waddington, G., 47.Wagner, C., 154, 157.Wagner, G., 149.Wagner-Jauregg, T., 353.Wahl, M. H., 112.Wain, R. L., 352.Waksman, S. A., 436, 437.Walden, P., 83.Waldmann, H., 411.Waldschmidt-Leitz, E., 309, 310.Walke, H., 11, 15.Walker, A. W., 291.Walker, 0. J., 59, 111, 113, 285.Walker, T. K., 446.Wallace, W.N. W., 279.Wallsom, H. E., 121.Waltnitzki, G., 246.Walton, H. F., 32, 33.Warburg, E., 408.Ward, A. G., 82.Ward, N. E., 163.Wardlaw, W., 145, 168.Waring, J. R. S., 10.Warren, B. E., 172, 173, 174, 178.Warschauer, F., 120.Washington, H. S., 464.Wassermann, A., 53.Watanabe, A., 452, 453.Watanabe, K., 295.Wetanab6, T., 183, 189.Waterman, R. E., 352, 353, 355.Waters, W. A., 264, 282, 283, 284,Watkins, J. S., 64.Way, W. J. R., 145, 168.Webb, D. A., 457, 458.Webster, I. M., 343.Wechsberg, R., 149.Wedekind, E., 333.Wedum, A. E., 291.Weibke, I?., 146.Weidenbaum, B., 66.Weigle, J., 39.Weiss, J., 44, 73, 74, 111.Weiss, L., 145.Weiss, P., 145.Weissgerber, R., 329.Weizmann, C., 74, 442.Weizshcker, C. F.von, 21.Weldon, L. H. P., 200.Welge, H. J., 68.285.Wells, A. F., 169.Wells, P. A., 446.Wells, R. C., 473.Wells, W. H., 12.Welo, L., 150.Wenck, P. R., 449.Wende, C. W. J., 274.Wendorlein, H., 370, 388.Wenger, P., 486.Went, J. C., 430.Werkman, C. H., 438, 439.Werr, F., 488.Wertyporoch, E., 252, 258.Wesely, F., 344, 345.West, C. D., 178.West, (Miss) H. L., 66.West, W., 57, 279, 280.Westenbrink, H. G. K., 401.Westerlind, S., 340.Westgren, A., 162.Westphal, K., 353.Whalley, H. K., 461.Whitaker, M. D., 23, 24.Whitby, G. S., 253.White, A., 314.White, A. H., 184.White, C. E., 487.White, C . M., 97.White, D. E., 450.White, H. L., 451.Wiberg, E., 134, 135, 152.Wick, H., 108, 109.Widdowson, E. M., 415, 416.Widenbauer, F., 404.Wiebenga, E. H., 183.Wiegand, W., 327.Wieland, K., 113, 234, 242, 251, 256,259, 285, 367, 368.Wierner, W., 246.Wien, M., 88, 89.Wienhaus, H., 236.Wiesenberger, E., 123.Wigner, E., 9, 45, 46.Wiig, E. O., 13, 66, 67, 68.Wild, G. L. E., 59, 113, 285.Wild, W., 56, 67, 270, 275, 279.Wiley, F. H., 459.Willard, J., 66.Willemart, E., 391.Williams, A., 46.Williams, D., 92.Williams, E. C., 237.Williams, J. H., 12.Williams, R. R., 352, 353, 355, 356,Williams, R. T., 297.Willstaedt, H., 395.Willstiitter, R., 235.Wilman, H., 199.Wilson, C. L., 41, 200, 349.Wilson, E., 260.Wilson, G. S., 413.Wilson, J. G., 27.401516 INDEX OF AUTHORS’ NAMES.Wilson, J. N., 54.Winans, C. F., 225.Windaus, A., 352, 353, 355, 409.Winkler, C. A., 57.Winkley, J. H., 484.Winter, K., 475.Winterfeld, K., 358.Winterstein, A., 327, 390.Wirtz, K., 34, 39, 40, 108.Wischin, A., 51.Wiskont, K., 474.Wislicenus, J., 397.Wittig, G., 231, 246, 247.Wohl, A., 252.Wohlgemuth, K., 342.Wohmann, M., 353.Wojciechowski, M., 34.Wojcik, B., 225, 226.Wolf, K. L., 92.Wolfenden, J. H., 32, 33.WoH, K., 72.Wood, H. G., 438, 439.Wood, W. C., 46, 59, 60, 61, 62.Woodward, (Miss) I., 186, 198,Wooldridge, D. E., 43.Woolley, D. W., 403, 449.Wooster, C. B., 243, 245.Work, T. S., 357, 411.Wormall, A., 425.Wrigge, W., 153, 491.Wright, D. D., 103.Wright, E. R., 477.Wright, G. F., 245.Wright, J. M., 255, 372.Wright, M. D., 414.Wright, N., 149.Wrinch, D. M., 311, 322, 323.Wurstlin, K., 477.Wulf, 0. R., 91.Wunsch, A., 265, 266, 275.Wyckoff, R. W. G., 161, 174, 427,Wyman, J., 87.Wynne-Jones, W. F. K., 37, 50.199.428, 431.Yagoda, H., 482.Yamagishi, T., 355.Yamasaki, I., 443, 449,Yanowski, L. I<., 484, 491.Yee, J. Y., 168.Yerkes, L. A., 486.Yntema, L. F., 129.Yoder, L., 409.Yorke, W., 399, 424, 425.Young, C . J., 423.Young, R. V., 245, 246.Young, T. F., 97.Young, W. G., 229.Yu, S. H., 167.Yudkin, J., 408.Zacharewicz, W., 240, 242.Zacharias, J. R., 8.Zachariasen, W. H., 162, 174.Zahn, C. T., 23.Zajic, E., 358.Zakomorny, M., 445.Zapf, G., 35.Zartman, W. H., 225.Zechmeister, L., 220, 222.Zeicher, M., 482.Zeiser, H., 249.Zeitschel, O., 236.Zelinski, N. D., 222, 257.Zentner, J., 36.Zernike, F., 171.Zervas, L., 290, 323, 324.Ziegler, K., 243, 244, 245, 248, 249,Ziervogel, M., 301.Zimmermam, J., 338, 339.Zinn, W. H., 14.Zintl, E., 138, 146.Z€otnek, A., 298.Zobell, C. E., 437, 438.Zoellner, E. A., 244, 246.Zuber, K., 26, 72.Zuckerkandl, F., 293.250, 342

ISSN:0365-6217    

DOI:10.1039/AR9373400493

出版商:RSC    

年代:1937

数据来源: RSC

摘要:

INDEX OE’ SUBJECTS.ACENAPHTHENE, crystal structure of,Acetaldehyde, oxidation of, to gly-photo-decomposition of, 55, 57,photo-oxidation of, 71.thermal decomposition of, 277.Acetanilide, N-chloro-, rearrange-nitroso-, decomposition of, 284.Acetic acid, and chloro-, dissociationconstants of, 102.and its potassium salt, electrolysisof, in deuterium oxide, 114.lead tetra-salt, as oxidising agent,auto-oxidation with, 237.photo-decomposition of, 59, 274.Acetic anhydride, oxidation of, toglyoxylic acid, 241.Acetone, formation of, by fer-mentation, 441.oxidation of, to methylglyoxal,239.photo-decomposition of, 56, 275,276, 283.189.oxal, 239.274, 277.ment df, 54.231.Acetonylacetone, oxidation of, 239.Acetophenone, preparation of, 255.Acetopyruvic acid, formation andmetabolism of, in tissues, 418.Acetoxyl, 285.10- Ace toxyphre oporphyrin a5, 3 8 1.10- Ace toxy-2 -vinylphaeoporphyrin u5,Acetyl, 270.Acetylene, carbon-hydrogen bondin, 204.silver salt, 381.oxidation of, to glyoxal, 241.photo-bromination of, 66.polymerisation of, ,induced byacetone, 281.2 - Acetylc yclohexane, 1 -chloro - , 256.2-Acetyl-l-methylcycZopentane, 256.Acetyl peroxide, photo-decompositionof, 69.N-Acetyl trime thy1 P-me thylglucos -aminide, 294.Achromobacter cystinovorum, form-ation of sulphur from E-cystineby, 435.Acids, a-fatty, crystal structure of,183.methyl esters, preparation of,263.Acids, transition of, to higher homo.weak, dissociation constants of,Acraldehyde, photo -decomposition of,Activity coefficients, 105.Adamine, crystal structure of, 166.Adipic acid, calcium salt, azuleneformed in distillation of, 397.Agranulocytosis from sulphanilamidetreatment, 423.Akerliif’s equation, 100.Albumin, egg, amino-acids from, 315.Alcohols, formation of, by oxidation,logues, 263.101.58, 278.structure of, 319.241.hydrogenolysis in, 225.structure of, 213.Aldehydes, aromatic, synthesis of,auto-oxidation of, 234.catalytic hydrogenation of, 223.photochemistry of, 277.2 -Aldehyde - 1 : 3 : 5 : 8 - tetramethyl-4 -vinylporphin - 6 : 7 - dipropionicacid, iron derivative, 370.Aldobionic acids, 299.Aldotrionic acid, 299.Algze, biochemistry of, 451.constituents of, 453.nutrition and metabolism of, 451.Aliphatic compounds, crystal struc-ture of, 180.Alkali halides, colour centres in, 157.effect of high pressures on, 142.osmotic coefficients of, 99.metals, determination and separ-ation of, in minerals, 473.organic compounds, 243.pentabromodiplumbates, crystalAlkaloids, 357.Alkyl halides, photo-dissociation of,tautomerism of, 268.Alkylation, 259.Allene, carbon-carbon double bondin, 199.Allylglucoside, alkaline degradationof, 288.Alpinone, 349.zpoAlpinone, 349.258.liquid, structure of, 173.structure of, 168.279.resonance energy in, 218.61518 INDEX OF SUBJECTS.Aluminium, detection of.micro- htimonv alkali halides, crvstalchemically, 487.als, 470.hydrogenation with, 228.chloride, preparation of, 262.use of, in syntheses, 251.metuphosphate, crystal structure of,166.isopropoxide, catalytic hydrogen-ation with, 229.determination of, in silicate miner-Aluminium alkoxides, catalyticAlunite, 167.Amides, hydrogenolysis of, 227.Amino-acids from protein hydrolysis,a-Amino-acids, preparation of, 323.Amino - compounds, infra-red spectraof, 91.Ammonia, photo-decomposition of,67.Ammonium salts, quaternary, form-ation and decomposition of, 54.Ammoresinol, 344.Amphibole, 165.trans-a-Amylcinnamaldehyde, auto-Amyrin, 339.dehydrogenation of, 330./3-Amyrin from wheat germ oil, 411.Amyrones, 339.Analysis, electro-drop, 482.inorganic, 480.microchemical, 220.in capillary tubes, 483.qualitative, 481.books on, 491.group separations in, 483.mineralogical, 464.organic, chromatographic adsorp -spectrographic, 454.volumetric, standards for, 480.311.mixed, analysis of, 312.oxidation of, 234.microchemical, 465.tion, 220.Anatabine, structure of, 358.dl- and Z-Anatabines, 358.Andalusite, 166.Andrade's equation, 81.Aneurin, 362.structure of, 363.synthesis of, 356, 401.Angelicin, 345.Anisole, Friedel-Crafts reaction with254.Anisotropy, diamagnetic, of aromaticcompounds, 184.Anthocyanins, 349.Anthracene, oxidation of, to anthraring size of, 202.Antimony, detection of, 486,490,491magnetic, of crystals, 186.quinone, 240.- " structure of, 168.ture of, 168.ture of, 168.Bromoantimoniates, crystal struc-Chloroant hnoniat es, crys t a1 st rue -qpatites, crystal structure of, 167.Qrginine, preparation of peptides of,krgon, disintegration of, 10.hromatic compounds, acylation of,325.isotopes, 43.separation of, 8.crystal structure of, 184.hydrogenation of, 225.position of, 69.iodine, 54.251.Arsenic trihydride, photo-decom-trioxide, crystal structure of, 180.Arsenic acid, reaction of, withArsenopyrits, crystal structure of, 161.Arundo donax, donaxine from, 357.Ascorbic acid, determination of, 404.synthetic, treatment of scurvyAsh bark, trihydroxycoumarins from,Aspergillus, acid production by, 445.fermentation of pentoses by, 448.Aspergillus Jischerei, sterol formationby, 449.Aspergillus Jclavus, xylose ferment -ation by, 448.Aspergillua niger, mineral nutrition of,443.Aspergillus oryzm, sugar fermentationby, 448.Aspergillus sydowi, phospholipins ofmycelium of, 449.Aspergillus terreus, metabolic pro-ducts of, 449.Aurofusarin, 450.Auto -oxidation, 2 33.Ayapin, 344.Azacoproporphyrin, 3 73.Aza-tetioporphyrin, 3 73.bicyclorl : 2 : 21Aza-l-heptane, 350.bicyclo[3 : 2 : 2]Aza-l-nonane, 351.Azaporphyrins, 3 72.Azomethane, photo-decompositionof, 73, 278.p-Azotoluene, crystal structure of,189.w-Azotoluene, decomposition of, 46.Azulene, preparation of, 396.Azulenes, 393.oxidation and reduction of, 395.with, 408.344.thermal decomposition of, 278.Bacteria, acetone-butenol, 441.biochemistry of, 432INDEX OF SUBJECTS.519Bacteria, gluconic, 441.lactic, 439.marine, 436.organic acids formed by, 438.propionic, 438.sulphur, 432.purple, pigments of, 435.purple and red, 432.Bacterium acetobutylicum, acetone-butanol formation by, 442.Bacterium gluconicum, gluconic acidformation by, 441.Bacterium granulobacter pectinouorurn ,acetone-butanol formation by,443.Bacterium xylinum, acid formationby, 441.Barium, detection of, 490.determination of, in rocks, 479.Barium chloride solutions, heat capac-ity of, 97.suboxide, 149.Barysilite, 165.Basalt, analysis of, 466.Bases, dissociation constants of, 103.organic, introduction of alkalimetals into, 248.Basseol, and its acetate, 340.Bayer 205, determination of, inblood-plasma, 425.trypanocidal action of, 425.Behrens tests, 489.Benzaldehyde, preparation of, fromBenzazaporphyrins, 374.Benzene, bromo-derivat’ives, carbon-benzene, 258.bromine bond in, 211.carbon-carbon bond in, 199.chloro-derivatives, structure of,210.iodo-derivatives, carbon-iodinebond in, 211.planarity of, 212.Benzenes, substituted, structure of,202.Benzenediazonium chloride, dry, de-composition of, 283.Benzoic acid, lead tetra-salt, as oxidis-ing agent, 231.Benzophenone, photo-dissociation of,269.Benzoylbenzoic acid, formation of,from phthalic anhydride, 255.Benzyl, 269.Benzyl alcohol, oxidation of, 239.Benzyl glycuronide, p-nitro-, methylester, 298.Benzylideneazine, decomposition of,46.Benzyl-lithium, 245.2-BenzylpyridineY action of copperon, 350.Bergamottin, 345.Bergapten, 345.isoBergapten, 345.Bergaptol, 345.Bsryllium, detection of, 491.rocks, 480.detection and determination of, indeuteron bombardment of, 14.proton bombardment of, 12.Betanidin chloride from beet, 349.Betulin, 340.dehydrogenation of, 330.alZoBetulin, 341.Biochemistry, animal, 399.plant, 426.Biological material, analysis of, byflame method, 457.Bismuth, detection of, 490, 491.effect of high pressures on, 141.liquid, structure of, 173.Bis - (7 : 8 : 3’ : 4’- tetrahydr0xy)flav-pinacol, 350.Black-tongue, factors preventing,403.Blood, determination in, of vitamin-B,, 401.Bond angles, 21 1.Bond lengths, 196.Bond radii, 213.Bonds, double, detection of, 328.Borax. See Sodium borate.Boric acids.See under Boron.Borine carbonyl, 151.Bornyl d-glycuronide, structure of,Boron, determination of, in rocks,Boron trifluoride in alkylation, 261.297.479.proton bombardment of, 12.hydrides, 150.oxides, 134.Boric acid, detection of, micro-dissociation constant of, 103.Boric acids, lower, 132.from, 349.chemically, 488.BougainvilZma glabra, anthocyaninBraggite, crystal structure of, 162.Brain, oxidation in, 419.in relation to vitamin-B,, 402.Bread, brown versus white, 414.nutritive value of, 413.Bromelin, protein hydrolysis by, 326.Bromine, crystal structure of, 178.neutron bombardment of, 19.Bromine oxides, 138.Bromides, detection of, micro-chemically, 488.3romoantimoniates. See underAntimony.Brucine, degradation of, 365.Brushite, crystal structure of, 167.Butaldehyde, photo-decompositionof, 55, 277520 INDEX OF SUBJECTS.Butane, 1 : 4-diiodo-, oxidation of,tert.-Butyl, 269.Butyl alcohol, formation of, byte.rt.-Butyl chloride, photo-chlorin-4-tert.-Butyl-2-furoic acid, 5-bromo-,Butyric acid, dissociation constant231.fermentation, 441.ation of, 66.ethyl ester, 260.of, 103.halides, decomposition of, 46.Cadmium, detection of, micro-chemically, 485.minerals, 473.409.deuteron bombardment of, 15.Casium, determination of, in silicateCalciferol, specification values for,Calcite, crystal structure of, 163.effect of high pressures and stressCalcium, deuteron bombardment of,Camazulene, 394.Camomile oil, azulenes from, 393.Camphor, oxidation of, 239.Carbobenzyloxy-group, introductionof, in syntheses, 323.Carbohydrates, 286.complexes of, with proteins, 295.containing nitrogen, 289.oxidation of, in animal tissues, 416.on, 144.15.disintegration of, 10.Carbohydrazidomethylp yridiniumchloride, 262.Carbohydrazidomethyltrimethyl-ammonium chloride, 262.Carbon, amorphous, structure of, 173.determination of, in minerals androcks, 474.deuteron bombardment of, 14.isotopes, 43.isotopic mass of, 7.Carbon tetraiodide, crystal structureof, 180.suhoxide, bond lengths in, 199.photo-decomposition of, 74.monoxide, oxidation of, in presencereactions with, 258.oxides, 149.Carbonic acid, dissociation con-stants of, 103.Carbon-carbon bond, 196.Carbonyl chloride, photochemicalformation of, 72.compounds, catalytic hydrogen-ation of, with aluminium alk-oxides, 228.group, reagents for, 262.of nitric oxide, 47.Carica papaya, carpaine from, 357.Carnosine, 6-aminopropionio acida-Carotene, crystal structure of,Carotenoids from purple bacteria,Carpaine, structure of, 357.Cartilage, chondroitinsulphuric acidCatalysts for auto-oxidation, 233.Catalytic hydrogenation, 22 1.Cathepsin, protein hydrolysis by,Cedrene, oxidation of, 236.Cells, concentration, thermal datafrom measurements on, 93.electrochemical, with transport,106.living, formation of proteins in, 325.papain from, 326.synthesis of, 324.from, 311.184.435.from, 296.for hydrogenation, 221.326.Cellobiose, lactic acid from, 288.Cellulose, structure of, 189.P-Centres, 158.Cerebrospinal fluid, trypanocidalpower of, in arsenical treatment,426.Cerium, ceric, detection of, micro-chemically, 487.magnetic properties of, 126.separation of, 130.Cerium nitride and phosphide, crystalstructure of, 159.Cerie salts, photo-reduction of, 73.sulphate, standardisation of solu-tions of, 481.Chalcocite, effect of high pressures andstress on, 144.Chemotherapy , 42 0.Chlorella ellipsoidea, respiration in,452.Chlorella lutes&ridis and vulgaris,growth and metabolism of 451.Chlorins, 376.Chlorin e, 377.Chlorin f, 380.Chlorin p s , 382.$-Chlorin ps, 382.Chlorine, disintegration of, 10.gen, 62.Chlorine oxides, 136.67.137.mony.66.absorption spectra of, 388.photo-combination of, with hydro-dioxide, photo-decomposition of,Dichlorine he@- and hex-oxides,Chloroantimoniates. See under Anti-Chloroform, photo-bromination ofINDEX 01Chlorophyll, 37 5.388.derivatives, absorption spectra of,leuco-compounds of, 384.oxidation of, 378.Chlorophyll-a, 375.Chlorophyll - b, 3 8 6.derivatives, oxidation and reduc-tion of, 387.isoChloroporphyrin e4, and its de-rivatives, 377.Cholestenone, separation of, 262.Cholesterol, antirachitic activation of,and its derivatives, 409.catalytic hydrogenation of, 230.Chondrosamine from chondroitin-sulphuric acid, 295.Chromanochromanones, 346.Chromium, determination of, in rocks,477.Chromic salts, anodic oxidation of,112.Cinchona alkaloids, 364./I-isoCinchonine, 364.Citric acid, formation of, by Asper-oxidation and synthesis of, inCitromyces, fat format ion by speciesCladophora Wrightiana, photosyn-Clausius-Mosotti formula, 85.Clostridiurn acetobutylicum, ferment-Clostridiurn butyricus, acetone form-Co-carboxvlase. relation of, t o aneu-gillus, 445.tissues, 418.of, 449.thesis in, 452.ation by, 442.ation by, 442.lactic acid formation by, 440.rin, 4th.Cocoa-bush.ervthrodiol from fruit of, - I 338.Codium laturn, photosynthesis in, 452.Colour centres, 157, 158.Combustion, gaseous, 48.Compounds, co-ordination, crystalstructure of, 167.Cooperite, crystal structure of, 162.Copper, detection in, of impurities,458.microchemically, 484.detection of, 490.determination of, in rocks, 479.neutron bombardment of, 17.“ Copper chromite,” catalytic, 224.Copper salts, effect of, on tobaccoCosmic rays.See under Rays.Coumarins, natural, 343.Cows, diet of, 413./3 -Crist obalite, cry st a1 structure of,101.Crotonaldehyde, photolysis of, 278..mosaic virus, 430.SUBJECTS. 521Cryolite, analysis of, 476.Crystals, chemistry of, 159.effect of high pressures and stressmolecular, 176.polar, electrolytic conductivity in,on, 144.154,lattice defects in, 154.Cubanite, crystal structure of, 162.Cucumber mosaic virus, 431.Culmorin, 450.Cyanogen :-Hydrocyanic acid, carbon-hydro-Cyanosis from treatment with sul-Cybotaxis, 172.Cyclotron, 11.Cysteine derivatives, removal of carb-oxybenzyloxy-groups from, 323.gen bond in, 204.reactions with, 258.phanilamide, 423.Daphne g e n h a , genkwanin from, 349.Deafness, vitamin-A deficiency in re-lation to, 400.7-Dehydrocholesterol as provitaminin skin, 409.Dehydrorubrene, 3 9 1.3-Demethylphylloerythrin, 388.3 - Demethylpyrrophsophorbide a,Denaturation, 303.Descloisite, 106.Deuterates, 37.Deuterium, deuteron bombardmentof, 14.exchange of, with hydrogen, 49.exchange reactions of, 40.mercury-sensitised, 70.properties of, 35.separation of, 32.Deuterium compounds, physical pro-hydroxido, exchange of, with ethyloxide, ionic activityproduct of, 104.Deuterons, nuclear disintegration by,Diabetes, treatment of, with mccinicPS-Diaza-aetioporpliyrin-11, 373.Diazacoproporphyrin, 373.Diazomethane, thermal decom-position of, 271.Dibenzyl, crystal structure of, 187.Dibenzyl ketone, decomposition of,269.Diborane, 152.388.perties of, 39, 41.alcohol, 51.properties of, 36.solubility of salts in, 38.14.acid, 417.oxidation of, to bend, 240.structure of, 203522 INDEX OF XJBJECTS.Di- tert.-but yl ketone, pho tolysis of,Dielectric constant, dispersion of, 87.Dielectric constants of polar liquids,Diet, 412.Diethyl ketone, photolysis of, 267,276.Diethylmonobromogold, dimeric,crystal structure of, 168.Dihydrobetulin, 341.Diketopiperazines in hydrolysis pro-ducts of proteins, 309.Dimethylbutadiene, action of lithiumalkyls on, 250.py-Dimethyl-day-butadiene, dimeris-ation of, 53.Dimethyldihydroresorcinol, seleniumcompound with, 242.2 : 5-D$nethylpyrimidine, 5 : 6-di-amino-, from aneurin, 355.Dioxan, thermal decomposition of,282.Diphenyl, structure of, 203.o-Diphenylbenzene, crystal structureof, 188.p-Diphenylbenzene, structure of, 203.Diphenyldichloronaphthalene, struc-ture of, 392.4 : 4’-Diphenyldiphenyl, structure of,203.Diphenylmethane, oxidation of, t obenzophenone, 240.Diphenyl disulphide, 4 : 4’-dinitro-,therapeutic action of, 421.Diphenylsulphone, 4 : 4’-diamino-,and its diacetyl derivative, and4 : 4’-dinitro-, therapeutic actionof, 421.Diisopropyl ether, explosive proper-ties of, 237.Di-m-propyl ketone, irradiation of,268.photo-decomposition of, 55, 57,276.Diisopropyl ketone, photo-decom-position of, 57.Dipyrroles, 350.Disaccharides, action of alkalis on,286.Diseptals, 422.Dispersion effect, 76.Dissociation constants, 101.in relation to temperature, 104.Distillation, molecular, 221.p-Dithiocarboxymethoxyphenol, 254.Dithioformic acid, chloro-, methylDolomite, analysis of, 465.Domesticine, structure of, 360.Donaxine, structure of, 357.Drop reactions, 484.Drugs, identification of, 483.269.84.ester, 254.Duboisia, alkaloids from species of,358.Durene, carbon-carbon bond in, 202.Dypnone, 255.Dysprosium, magnetic properties of,127.valency of, 123.Earths, rare, anomalous valency in,atomic volumes of, 124.determination of, in silicaterocks, 479.isolation of, 145.magnetic properties of, 126.polyselenides of, 124.separation of, and preparationof pure compounds, 128.table of iso-electronic arrange-ment of ions of, 123.Ectothiorhodospira mobile, effect ofsulphur on growth of, 434.Electric arc in spectrographic ana-lysis, 457.spark in spectrographic analysis,458.122.Electrochemistry, 92.Electrolytes, mixed, 99.theory of concentrated solutions of,97.Electrolytic conductivity in polarcrystals, 154.Elemazulene, 394.Elements, and their compounds,polymorphism of, a t high pres-sures, 140.isotopic constitution of, 7.Elemi resin, amyrin from, 339.Elemol, azulene from, 394.Enamels, determination in, of fluor-Enzyme, yellow, protein bearer in,Epidote, determipation in, of water,Equations of state, 78.Erbium, magnetic properties of, 127.Erdin, 450.Erythrodiol, 338.Esters, hydrogenolysis of, 225.Ethane, nitro-, photo-decompositionof, 282.Ethers, auto-oxidation of, 237.Ethyl, 267.Ethyl alcohol, exchange of, withdeuterium hydroxide, 51.infra-red spectrum of, 91.oxidation of, t o glyoxal, 240.nitrite, decomposition of, 46.Ethylene, benzoylation of, 256.carbon-carbon double bond in, 199.ine, 476.315.474.hydrogenolysis of, 225INDEX OF SUBJECTS.523Ethylene, carbon-hydrogen bond in,chloro-derivatives, bond angles in,tetrachloro -? photo -bromination ofdiiodide, photo-decomposition of ,oxidation of, t o glyoxal, 240.photo -chlorination of , 6 6.polymerisation of, induced byacetone, 281.Euglena, constituents of, 453.Euglenarhodone, 453.Eupatorium ayapana, ayapin from,Europium, absorption spectrum of,magnetic properties of, 127,purification and separation of, 129.Excelsin, effect of X-rays on crystals204.212.structure of, 209.66.60.344.131.of, 311.“ Fehlordnungserscheinungen,” 157.Ferric oxide and salts.See underFerrocyanides, crystal structure of,Fibroin, silk, 303.Flames in spectrographic analysis,457.Flavones, 349.Flavonols, 349.Flavoprotein, amino-acids from, 316.analysis of, 312.Flavpinacols, 349.Flax-seed mucilage, aldobionic acidfrom, 299.Fluorenes, 9 -chloroamino -, Stieglitzrearrangement of, 35 1.Fluorine, determination of, inminerals and rocks, 476.proton bombardment of, 12.Fluorine oxides, 136.Formaldehyde, photolysis of, 278.photo-oxidation of, 71.Formic acid, dissociation constant of,photo-chlorination of, 66.photolysis of, 274.Iron.168.103.Formyl, 274.Fraxetin, 344.n- and iso-Fraxidins, 344.Fraxinol, 344.FriedelLCrafts synthesis, 25 1.Fries rearrangement, 254.Fruits, acid-producing bacteria of,441.Fucoidin, 453.Fumaric acid, effect of, on respirationin tissues, 419.Furan derivatives, alkylation of, 261.Pusariurn culmorum, pigments from,450.Gadolinium, absorption spectrum of,Galactose, action of alkalis on, 286.Galacturonic acid and its derivatives,Gallium, detection of, 491.preparation and properties of, 147.Gallium halides, photo-dissociation of,nitride, crystal structure of, 159.Garnets, analysis of, 466.Gas reactions, 46.Gases, combustion of, 48.Gattermann-Koch reaction , 2 5 8.Gehlenite, crystal structure of, 164.Gelatin, amino-acid content of, 315.Genkwanin, 349.Gentiobiose, lactic acid from, 288.Geodin, 449.Germanin.Xee Bayer 205.Germanium, detection of, micro-Glass, determination in, of fluorine,quartz, effact of high pressures andstructure of, 174.Gluconic acid, formation of, by bac-teria, 441.Gluconoacetobacter cerinus var. am-moniaczcs, acid production by,441.132.magnetic properties of, 127.298.74.analysis of, 312.chemically, 485.476.stress on, 144.Glucoproteins, 295.Glucosamic acid, reduction of, 292.Glucosamine, deamination of, 290.determination of, 292.from heparin, 295.isolation of, 292.reduction of, 292.mutarotation of, 50.Glucose, action of alkalis on, 286.Glucosidodihydroxyacetone, alkaline2-Glucosidoerythrose, 289.Glutaminylcysteine, preparation of,Glutathione, synthesis of, 323.Glycerides, crystal structure of, 183.Glycine, crystal structure of, 180.Glycollic acid, dissociation constantGlycollic acid, O-amino-, 263.Glycols, oxidation of, 231.Glycuronic acid, 296.bacterial formation of, 441.degradation of, 288.324.determination of, 314.of, 103524 INDEX OF SUBJECTS.Glycyl-d-glucosamic acid, action ofdipeptidase on, 290.Glycyl-d-epiglucosamic acid, action ofdipeptidase on, 290.Glycyrrhetic acid, 339.dehydrogenation of, 330.Glycyrrhizin, hydrolysis of, 300.Gold, detection of, 487, 490.neutron bombardment of, 16.Graham's salt, 116.Gramine, identity of, with donaxino,357.Graphite, effect of high pressures andstress on, 144.Grignard reagents, 246.Growth substances for bacteria, 439,440.8- Guaiacazulene, 3 94.Se-Guaiacazulene, 394.Guanidines, trypanocidal action of,Z-Guluronic acid, 441.Gum benzoin, sumaresinolic acidGypsogenin, 338.399, 424.from, 339.dehydrogenation of, 330.Hsemin, Spirographis, structure of,Hamocyanin, mol.wt. of, 306.Hzemoglobin, cattle, amino -acidsfrom, and its structure, 318.Hemoglobins, constituents of, 314.Hulicystis, cell-wall constituents of,453.Halides, electrolysis of, in solution,111.Halogens, light absorption by, 59.oxides of, 136.photochemical reactions with, 62.Hamlinite, 167.Hardystonite, crystal structure of,164.Heat of hydrogenation of unsatur-ated hydrocarbons, 214, 216.Hederagenin, dehydrogenation of,330.370.'oxidation of, 331.structure of, 335.Helium, liquid, structure of I and I1forms of, 176.solid, stability of, 78.Helix pomutia, hzemocyanin from, 306.Helminthosporium species, metabolicproducts of, 450.Hemimorphite, 165, 166.Hens, vitamin-A in, and in eggs,400.Heparin, 294.anti-coagulating action of, 295.n-Heptane, reaction of, with alumin.ium chloride, 261.Ieterocyclic compounds, 342.leteropoly-acids, crystal structureof, 169.lexamminocobaltic chloride as re-agent in qualitative analysis, 491.a-Hexane, reaction of, with alumin-ium chloride, 261.ycZoHexane, photo-decomposition of,55.ycZoHexanone, oxidation of, 239.:ycZoHexene, acetylation of, 256.oxidation of, in presence of os-y-dl-cycloHexenylbutyry1 chloride,Hsxonic acids, classification of, 290.Higginsite, 166.Uigika fwiformia,constituents of, 453.Histidine, preparation of peptides of,Kofer-Moest reaction, 113.Huckel equation, 95.Hydrazobenzene, crystal structure of,Kydrides, photochemical reactionsHydrindene, resonance energy in, 219.Hydrocarbons, addition of organo-acylation of, 255.hydrogenation of, 225.mium, 235.cyclisation of, 257.325.189.of, 67.alkali compounds to, 249.bond lengths in, 196.combustion of, 49.cyclic saturated, auto-oxidation of,free-radical theory of dissociationhalogen derivatives, structure of,introduction of alkali metals into,unsatura t ed , heat of hydrogenation237.of, 280.206.248.of, 214.resonance energy of, 218.in associated liquids, 89.exchange of, with deuterium, 49.exchange reactidns of, mercury-sensitised, 70.ions, equilibria involving, 51.isotopes, exchange reactions of, 39.separation and analysis of, 34.overvoltage, 107.photo-combination of, with chlor-ine, 62.Hydrogen cyanide.See Hydrocyanioacid under Cyanogen.peroxide, formation of, in anodicoxidation, 112.sulphide, solid, crystal structure of,179.Hydrogen bonds, 177, 213.Hydrogen-t ransport ases, 4 1 6.Hydrogenation, 221INDEX OF SUBJECTS.525Hydrogenolysis, 225.Hydroxy -compounds, hydrogen bondsin, 213.infra-red spectra of, 91.Hydroxyl, 272.bonds, 177.Hypophosphites. See under Phos-in associated liquids, 89.phorus.Ice, jl-form, crystal structure of, 178.n- and iso-Imperatorins, 345.Indium, deuteron bombardment of,Indole alkaloids, 357.~-3-IndolylethylamineY formation of,Induction effect, 76.Inorganic analysis, 480.Insulin, electrometric titration of,Integral theorem, Fourier’s, 171.Intermolecular forces , 7 5.Iodine vapour, extinction coefficientof, 59.Iodine oxides, 139.Iodides, detection of, microchemic-ally, 488.Periodic acid as oxidising agent,230.Periodates, crystal structure of,163.Iodof orm, photo-decomposition of ,66.Ions, complex, crystal structure of,167.Iridecea, flavin in species of, 453.Iridium, detection of, 490.neutron bombardment of, 16.Iron, detection of, microchemically,15.from strychnine, 365.309.487.in foods and in the body, 416.in nutrition of moulds, 444.Ferric oxide, determination of, inrocks and minerals, 471, 472.Ferrihexafluorides, crystal struc-salts, photo-reduction of, 73.ture of, 168.ium, 249.IsQmerism, nuclear, 2 1.Isoprene, polymerisation of, by sod-Isotopes, 7.non-radioactive, 32.Kadsura japonica, aldobionic acidKamala, Indian, rottlerin from, 348.Keratin, 303.p-Keratin of wool, 320.Ketones, aromatic, formation of, 255.catalytic hydrogenation of, 223.from, 299.Ketones, from higher paraffins, 257.Kinetics, chemical, 43.Kirchhoff equation, 95.Knorre’s salt, 116.Kojic acid, bacterial production of,formation of, from xylose ferment-ajl-unsaturated, auto-oxidation of,237.441.ation, 448.Kolbe reaction, 113.Kolbeckite, analysis of, 465.’Krypton, isotopes, 8.‘‘ Kurrol ” salts, 117.Lactarazulene, 394.Lactarius deliciosus, azulene from,Lactic acid, dissociation constant of,formation of, by bacteria, 439.Lactobacillus, lactic acid formation byspecies of, 440.Lactobacillus caucasica, growth factorfor, 441.Lactobacillw delbriickii, growth fac-tors for, 440.Lactoflavin, 403.Lactose, lactic acid from, 288.Laminaria digitata, fucoidin from,453.Lanthanum, magnetic properties of,126.Lanthanum nitride and phosphide,crystal structure of, 159.Lead, detection of, 490.determination of, in blood, 458.in rocks, 479.liquid, structure of, 173.Lead halides, photo-dissociation of,oxide, new, 150.oxides, action of light on, 74.tetra -e th y 1 , thermal decompositiontitanate, crystal structure of, 161.Lemna, dutrition and metabolism of,dl-Leucine, enzymic resolution of, 326.Libethenite, 166.Light, ultra-violet, sources of, 75.Liquids, associated, hydrogen andhydroxyl bonds in, 89.partition functions of, 78.polar, dielectric properties of, 84.scattering of X-rays by, 170.structure of, 169.surface tension of, 84.viscosity of, 81.384.103.74.of, 263.451.Liquorice, saponin from, 339.Lithium, determination of, in rocks,473526 INDEX OF SUBJECTS.Lithium, deuteron bombardment of,14.isotopes, 43.separation of, 8.nuclear spin of, 8.proton bombardment of, 11.Lithium alkyls and aryls, 244.chloride, liquid, structure of, 173.Liver, human, vitamin-A content of,ox, extraction of heparin from, 294.pig’s, cathepsin from, 326.Logarithmic sector, 460.Lupaiiine, structure of, 358.Lupeol, dehydrogenation of, 337.Lupin alkaloids, 358.dl-n- and -480-Lupinines, synthesis of,Lutecium, magnetic properties of,Lycoramine, 363.Lycorine, structure of, 362.Lycoris, alkaloids from, 362.Lysine, preparation of peptides of,400.359.127.324.Macleod’s equation, 84.Maddrell’s salt, 116.Magnesium, detection of, micro-chemically, 488.determination of, in silicateminerals, 472.in nutrition of moulds, 443.hydrogenation with, 230.ture of, 168.structure of, 168.166.elements, 126.439.oxide on, 287.degradation 01, 289.Magnesium alkoxides, catalyticchlorite hexahydrate, crystal struc-nitrate, urea compound, crystalpyrophosphate, crystal structure of,Magnetic susceptibility of rare-earthMaize, bacterial growth factor in,Maltose, action of potassium hydr-Mandelic acid, photo-oxidation of, 72.Mandelic acid, ethyl ester, oxidationManganese, detection of, micro-determination of, in minerals andManganese dioxide, and its salts, inMarcasite, crystal structure of, 161.Melibiose, lactic acid from, 288.Melilite, crystal structure of, 166.Melting, 83.Menschutkin reaction, 45.of, 239.chemically, 487.rocks, 472, 478.auto-oxidation, 234.dl-p-Menthene, oxidation of, 240.d3-p-Menthene, oxidation of, 240.Mercury, effect of high pressures on,vapour, photo-oxidation of, 72.Mercury salts, effect of, on tobaccomosaic virus, 430.Mesityl oxide, synthesis of, fromisobutylene, 256.Mesochlorin p6, 382.Meso-#-chlorin p6, 382.MesophEophorbide a, 382.Metabolism, carbohydrate inter -Metals, detection of corrosion of, bydissolution of, in acids, 52.of the ammonium sulphide group,analysis of, 484.of the chromium group, analysis of,484.Metallic chlorides, anhydrous, assubstitutes for aluminium chlor-ide in syntheses, 253.Metaphosphates.See under Phos-phorus.Methane, carbon-hydrogen bond in,204.141.mediary, in embryos, 420.sea-water, 483.combustion of, 48.photo-decomposition of, 67.thermal decomposition of, 271.Me thane, fluoro -derivat ives, s true -ture and properties of, 207.halogeno-derivatives, bond anglesstructure of, 205, 206.nitro-, photo-decomposition of, 282.streaming through quartz tube,products from, 275.nitrate, structure of, 213.in, 212.Methyl, 267.Methyl ether, decomposition of, 47.Met hylace t y lene , carb on-carb on bondZ-N-Methylanabesine, 358.Z-N-Methylanatabine, 358.O-Methylbebeerhe, structure of, 360.Methyl rt-butyl ketone, photo-Methylene, 270.Methyleneformamidine, chloro-, 259.1-Methyl-dl-cyclohexene, oxidationMethylcyclohexenes, auto-oxidation1 -Methyl-d -cycZopentene, oxidationMethylphzophorbide a, synthesis of,Mica, analysis of, 474.Microphotometer, 461.in, 197.decomposition of, 56, 57.esters, decomposition of, 46.iodide, photo-oxidation of, 71.of, 241.of, 236.of, 241.386INDEX OF SUBJECTS.521Milk, cow’s, vitamin-D content of,supply and value of, 413.Minerals, analysis of, 464.atomic structure of, 159.classification of, 164.detection of elements in, 490.radioactive, analysis of, micro-silicate, sampling of, 468.410.chemically, 466.Mirrors, tellurium, standard, 266.Molecular weights of proteins, 304.Moloxides, 233.Molybdenum, detection of, micro-determination of, in rocks, 477.Moulds, biochemistry of, 443.fat and sterol formation by, 449.metabolism of, 449.Monazite sand, determination in, ofMonosaccharides, action of alkalis on,Mucin, gastric, of pigs, polysac-Mucoproteins, 295.Mud, marine, bacteria in, 436.Muscle, contraction of, 420.Muscovite, 165.Mussel shells, porphyrin in, 371.chemically, 486.thoria, 479.286.charides from, 296.of Black Sea, bacteria in, 438.Naphthacene, purification and prop-Naphthalene, carbon-carbon bondsNaphthalocyanines, 3 72.Narcotics, effect of, on brain oxid-Neodymium, isotopes of, €4-Neon, disintegration of, 10.Neutrons, action of, with protons,magnetic moment of, 23.nuclear disintegration by, 16.determination of, in rocks, 477.Raney, as catalyst, 222.Nickel carbonyl, detection of, micro-phthalocyanine, crystal structureNicotinic acid, relation of, t o vitamin-Nicotyrine, 358.Nitriles, reaction of, with organo-Nitroamide, decomposition of, 50.Nitrogen, fixation of, by algae, 452.erties of, 390.in, 201.ation, 420.magnetic properties of, 126.22.Nickel, detection of, 490.chemically, 483.of, 187.B, complex, 403.alkali compounds, 248.isotopes, 43.ring compounds, 350.Nitrogen monoxide, photo-decom-position of, 74.Nitrates, detection of, microchemic-ally, 488.Nitrites, detection of, microchemic-triple, crystal structure of, 167.ally, 488.Nitrosyl chloride, formation of, 47.Nornicotines, 358.Norrubrofusarin, 450.Nostoc muscorum, nitrogen fixationby, 452.Nuclei, disintegration of, by deu-terons, 14.by neutrons, 16.by a-particles, 10.by protons, 11.isomerism of, 21.moments and spins of, 8.photo-effect of, 20.theory of, 9.Nutrition, 412.Oat husks, aldotrionic acid fromhemicellulose of, 299.Octalin, ozonolysis of, 396.cis-[0 : 3 : 3]-bicycZoOctane, reaction of,with aluminium chloride, 261.Octaphenyltetra-azaporphin, 374.Oils, essential, azulenes from, 393.Oleanolic acid, dehydrogenation of,330.oxidation of, 331.structure of, 335.Olefins, acylation of, 251, 256.auto-oxidation of, 233, 237.catalytic hydrogenation of, 223,oxidation of, 235.Oleic acid, butyl ester, catalyticOligosaccharides, alkaline degrad-Olivenite, 166.Olivine, 165.Oreoselone, 344.Organic compounds, structure andOrthoclase, 165.Orysterols, 411.Osmium, detection of, 490.isotopes, 8.Osteomyelitis, vitamin-C in, 407.Osthenol, 344.Osthol, 344.Ostruthin, 344.Ostruthol, 345.Overfeeding, effect of, on proteinOvsrvoltage, 107.Dvomucoid, 295.224.hydrogenation of, 227.ation of, 288.stereochemistry of, 196.microchernically, 485.metabolism, 415528 INDEX OF SUBJECTS.Oxalic acid, formation of, by Asper-dihydrate, structure of, 198, 202,214.Oxa,lic acid, chromium potassiumsalt, as reagent for glycine, 314.Oxaloacetic acid in tissue oxidation,417.Oxal yl chloride, photo - dec omp osi tionof, 67.Oxidation, 230.anodic, 110.Oxides, preparation of, 242.Oxorhodoporphyrin, synthesis of, 379.Oxygen isotopes, 42.Oxypeucedanin, 345.Ozone, action of, on bromine, 139.gillzls, 445.photosynthesis of, 75.ring compounds, 342.Palitantin, 450.Palladium, detection of, 490.deuteron bombardment of, 15.Palladous sulphide, crystal struc-Palladium-carbon, dehydrogenationPapain, protein hydrolysis by, 326.Paraffis, acylation of, 256.cycZoPara%hs, acylation of, 256.reactions of, with aluminium chlor-Paraldehyde, depolymerisation of, 50.a-Particles, nuclear disintegration by,Partition functions of liquids, 78.Pectic acid, 301.Pectin, 300.Pellagra, vitamin factors preventing,Pelvestrol, 453.Penicillic acid, 450.Penicillium palitans, metabolic pro-Penicil lium terrestre, terres tric acidday-Pentadiene, dimerisation of, 53.cycloPentadiene, dimerisation of, 53.Pentaerythritol, crystal structure of,Pentane, liquid, photo-chlorinationcycZoPentane ring, strain in, 219.cyclopentene, oxidation of, 241.Pentoses, fermentation of, by Asper-Pepsin, inactivation of, 53.Perbenzoic acid, oxidation with, 242.Percamphoric acid, oxidation with,ture of, 162.by, 329.reactions of, with aluminium chlor-ide, 261.ide, 261.10.403.ducts of, 450.from, 450.178, 181.of, 66.g i l l u s , 448.242.Perhydroxyl, 273.Periodates and Periodic acid.Seeunder Iodine.Perphthalic acid, oxidation with, 242.Per-rhenates. See under Rhenium.Peucedanin, 344.PhEophorbide b, catalytic reductionof, 387.Phaeophorbides, ring fission of, 378.PhEoporphyrin a, esterification of,386.Phsoporphyrins, 376.Phsoporphyrinogen a5, colourless,Phaeopurpurin, degradation productsPhaecpurpurin-7, 381.structure of, 385.Phsopurpurin- 18, 382.Pharmacolite, crystal structure of , 167.Phenacite, 165.Phenanthrene, catalytic hydrogon-Phenanthridine derivatives, 351.Phenol, infra-red spectrum of, 91.Phenols, and their ethers, acylationof, 254.Phenols, dihydroxy-, cyclic ethers of,342.Phenyl, 269.in solution, 285.Phenylacet ylene, o- hydroxy -, form-ation of, 343.1-Phenylalanyl-d-glucosamic acid,action'of dipeptidase on, 290.Phenylazotriphenylmethane, decom-position of, in solution, 285.1-Phenylbutadiene, polymerisationof, 249.Phenylhydrazine, 2 : 4-dinitro-, asreagent for carbonyl group, 263.Phenylhydrazine-p-carboxylic acid,262.Phenylisopropylpo tassium, 243.Phenylsodium, 245.Phlobatannins, 349.Phorbides, 376.absorption spectra of, 388.Phorbins, 376.Phosphorus, structure of, 174.Phosphorus acids, 148.384.of, 379.ation of, 227.hydrides, 153.photo-decomposition of, 69.peToxide, 148.pentoxide, determination of, inrocks, 475.oxides, crystal structure of, 180.Phosphoric acid, dissociation con-Hypophosphites, hexahydrated,Metaphosphates, 115.Polyphosphates, 121.stants of, 103.crystal structure of, 168INDEX OF SWJECTS.529Photochemistry, 54.Photo-oxidation, 70.Phthalocyanine, structure of, 37 1.Phthalocyanines, metallic, 37 1.Phylloerythrin, 376.Phytyl allophanate, 412.Pigments, macrocyclic, 369.white, action of light on, 75.Pineapple, bromelin from, 326.Pinene, auto-oxidation of, 236.oxidation of, 240.Piperitone, oxidation of, 239.Plants, detection in, of heavy metals,photosynthesis of acids in, 75.Plant viruses, 426.serological properties of proteins of,Platinum, detection of, 490.neutron bombardment of, 16.Platinum oxide, catalytic, 221.Polonium, crystal structure of, 159.Polymerisation, 53.by alkali metals, 249.Polymorphism a t high pressures,of compounds a t high pressures,Polyphosphates. See wnder Phos-Polyuronides, 297.hydrolysis products of, 299.Porphin, and its derivatives, 370.Porphin - 1 : 3 : 5 : 7 -tetra - acetic -2 : 4 : 6 : 8-tetra-p-propionic acid,371.Porphyrins, 369.conversion of, into chlorins, 386.nomenclature for, 370.Potassium, determination of, in rocks,in nutrition of moulds, 443.magnetic moment of, 8.Potassium metaborate, crystal struc-chloride, liquid, structure of, 173.permangana te , s t andardisa tion ofsolutions of, 481.Pot-curare, alkaloids from, 361.Potential, thermal data for measure-ments of, 92.Praseodymium, magnetic propertiesof, 126.Praseodymium nitride and phos-phide, crystal structure of, 159.Pressure, high, effect of, on elementsand compounds, 140.Proline, determination of, 313.Promotors in catalysis, 223, 224.Prontosil, 420.Prontosil S, 420.Propaldehyde, photo-decompositionof, 57.483.431.140.table of, 143.phorus.473.ture of, 162.Propionibacteriurn I I , effect of sulphurPropionibacteriurn pemtoaceticzcm,Propionic acid, dissociation constantn-Propyl, 268.n-Propyl nitrite, decomposition of,46.Propylene, oxidation of, to methyl-glyoxal, 240.Proteins, analysis of, 311.chemistry of, 302.classification of, 303.complexes of, with carbohydrates,denaturation of, 303.mol.wt. of, 304.effect of denaturation on, 308.table of, 305.synthesis of, 323.Protheca zap$, growth and meta-bolism of, 451.Protocuridine, 361.neoProtocuridine, 361.Protons, action of, with neutrons,compounds on activity of, 438.growth factors for, 439.of, 102.formation of, by bacteria, 438.295.22.magnetic moment of, 8.nuclear disintegration by, 11.Protoseptasine, 421.Psoralene, 345.Puerperal fever, treatment of, withPurpurins, 376.Pyridine alkaloids, 358.Pyridocolines, 350.Pyrolusite, crystal structure of, 161.Pyrrochlorin, 380.Pyrrocolines, 350.Pyrrole alkaloids, 357.P yrroporph yrin , 3 8 0.sulphanilamide, 423.absorption spectra of, 388.hydrogenation of, 386.Quartz, determination of, in silicatea-Quartz, crystal structure of, 161.Quinhydrones, crystal structure of,Quinidine, action of acids on, 364.isoQuinidines, 364..Quinine, action of acids on, 364.a- and ,&iso&uinines, 364.apo- and.isoapo-Quinines, 364.Quinizarinqunone, dichloro-, con-densation of, with hydrocarbons,236.Quinoline, 8-hydroxy-, in minera-logical analysis, 470, 472.~80Quinoline alkaloids, 359.Quinuclidine, 351.minerals, 469.189530 INDEX OF SUBJECTS.Radicals, free, 264.gaseous, isolation of, 265.half-value period of, 266.liquid, 283.metallic alkyl and aryl comRadioactive elements, table of, 11.Radioactivity, artificial, produce(produced by neutron bombardproduced by protons, 13.Rana esculenta, carbohydrate fromalbuminous gland of, 296.Resonance, 9.Ravenelin, 450.Rays, cosmic, 26.resonance, sources of, 75.P-Rays, disintegration by, 23.passage of, through matter, 25.y-Rays, emission of, on protonneutron extraction from nuclei by.passage of, through matter, 25.X-Rays, scattering of, by liquids, 170.Reactions, chemical, kinetics of, 43.exchange, heterogeneous, 41.exchange, homogeneous, 39.in solution, 50.selective and specific, 489.Reagents, selective and specific, 489.Reinecke’s salt, 313.R,esonance energy, 218.Rhenium, detection of, 485, 491.pounds from, 266.by a-particles, 11.ment, 16.bombardment, 11.20.Per-rhenates, crystal structure of,Rheumatoid arthritis, vitamin4 in,Rhizopenin, 450.Rhixopus juponicus, fat formation by2phosphoprotein from, 450.Rhodanilic acid, ammonium salt, asreagent for proline, 313.Rhodin g, derivatives of, 386.Rhodium, detection of, 490.Rhodobacillw palustris, 433.Rhodochlorin, 380.Rhodopin, 435.Rhodoporphyrins, 380.Rhodopurpurene, 435.Rhodospirillum gigunteum, ntilisationof sulphur compounds by, 434..Rhodovibrin, 436.Rhodovibris, pigments of, 435.Rhodoviolascene, 435.Rice germ oil, products from, 411.Rocks, analysis of, 464.silicate, sampling of, 468.Rock salt, electrolytic conductivityRottlerin, structure of, 348.163.408.449.of, 154.Rubidium, determination of, inRubrene, photo-oxidation of, 71.IL-Rubrene, structure of, 390.Rubrenes, 389.Rubrofusarin, 450.Ruthenium, detection of, 490.silicate minerals, 473.structure of, 389.Salts, solubility of, in deuteriumSamarium, absorption spectrum of,magnetic properties of, 126.Samarous chloride, preparation of,Sanguinaria canadensis, alkaloidSanguinarine, hydroxy-.36Sapogenins, 327.Sapotaline, 328.Scandium, deuteron bombardment of,preparation and properties of, 146.Scurvy, cure of, 406, 408.Sea water, bacteria in, 436.Selenium, dehydrogenation by, 328.detection of, microchemically, 486.Selenium dioxide as oxidising agent,Selenones, cyclic, 242.Serum mucoid, 295.Shea nut oil, basseol from, 340.Shearing stress, effect of, on crystalsSiaresinolic acid, dehydrogenation of,Wane, photo-decomposition of, 69.photo-oxidation of, 70.3ilicon dioxide, determination of, insilicate minerals, 468.pyrophosphate, crystal structureof, 164.silver, detection of, 484, 490.Silver bromide, density and latticeconstant of, 157.salts, effect of, on tobacco mosaicvirus, 430.skin, provitamin in, 409.Sleeping sickness, treatment of, 399,Soapwort, saponin of, 338.;odium, determination of, in rocks,oxide, 38.131.129.from, 364.15.238.crystal structure of, 160.and glasses, 144.330.425.473.liquid, structure of, 173.polymerisation by, 250.proton bombardment of, 13.use of, in liquid ammonia in syn-!odium borate (borax) as volumetrictheses, 325.standard, 480INDEX OF SUBJECTS.531Sodium metaborate, crystal structureof, 163.chloride crystals, structure of, 156.solutions, thermal properties of,97.symptoms of deprivation of,415.nitrate, crystal structure of, 163.metaphosphates, 11 5.polyphosphates,lZl.thiosulphate, preservation of solu-Solids, amorphous, structure of, 169.Soluseptasine, 42 1.Soyasapogenol B, dehydrogenationof, 330.Specific ionic interaction, 97.Spectra, absorption, of non-tervalentrare-earth ions, 131.emission, determination of inten-sity of lines in, 460.homologous line pairs in, 456.Spectrographic analysis, collectingdevices for radiation in, 459.production of radiation for, 456.Spectrum analysis, bibliography andtables of, 463.by emission spectra, 454.Spirilloxanthin, 436.Spirillum rubrum, pigment from, 436.Stearanilide, photo-decomposition of,Stereochemistry and structure ofSterols, 327.Stilbene, addition of phenylisopropyl-tions of, 481.74.organic molecules, 196.potassium to, 249.crystal structure of, 186.oxidation of, to bend, 240.structure of, 203.Streptococczcs lactis bulgaris, lacticStreptococcus varians, assimilation by,Strontium, determination of, in rocks,acid formation by, 440.433.478.deuteron bombardment of, 15.isotopes, 8.Strychnine, structure of, 365.Strychnos alkaloids, 365.Styrene, auto-oxidation of, 235.Styrene, 8-cyano-, isomerisation of, 46.Succinic acid in tissue oxidation, 416.Succinic acid, ethyl ester, oxidationof, 238.Sulphamoglobin in blood of patientstreated with sulphanilamide, 423.polymerisation of, 249.Sulphanilamide, chemotherapy with,determination of, in blood and398, 420.urine, 422.toxic effects of, 423.Sulphomonas th?iodzidans, formationof sulphuric acid by, 435.Sulphones, preparation of, 242.Sulphoxides, preparation of, 242.Sulphur, detection of, microchemic-in nutrition of moulds, 444.monoclinic, crystal structure of, 178.ring compounds, 342.Sulphur monoxide, 148.dioxide, photo-decomposition of,trioxide, crystal structure of, 179.Sulphuric acid, dissociation constantSulphites, electrolysis of, 110.Thiosulphates, electrolysis of, 110.Sumaresinolic acid, 339.dehydrogenation of, 330.Sumatrol, constitution of, 348.Surface tension of liquids, 84.Synthalin, trypanocidal action of,Syphilis, arsenicals for treatment of,ally, 488.74.of, 103.424.426.Tangerines, tangeritin from peel of,Tangerit in, 3 49.&Tartaric acid, ethyl ester, oxidationof, 239.Tellurium, detection of, 491.Tellurium &oxide, crystal structureof, 160.Terrein, 450.Terrestric acid, 450.Test papers for analysis, 482.Tetra -aza - ae t ioporph yr in, 3 74.Tetra-azaporphyrins, 373.Tetrabenzmonoazaporphin, 374.Tetradeuteroammonium chloride,structure of, a t low temperatures,39.Tetradeuteromethane, melting andtransition points of, 39.5 : 6 : 7 : 8-Tetrahydrophenanthr-idines, dehydrogenation of, 351.Tetrahydropyran-4-acetic acid, ethylester, 350.Tetralin, auto-oxidation of, 238.@-Tetralone, 236.Tetramethyl-lead, photolysis of, 73.Te t rame t h ylsilic on , decompositionTetraphenylethane, disodio - deriv-Tetraphenyl-lead, photolysis of, 73.5 : 6 : 11 : 12 - Tetraphenylnaphtha -Thermal properties and concentra-349.oxidation of, 236.of, 46.ative, oxidation of, 231.cene, synthesis of, 391.tion of solutions, 96532 INDEX OF SUBJECTS.Thianthren, crystal structure of, 189.Thiobacillzcs novellus and thioparus,utilisationof nitrogen and sulphurby, 434.Thiochrome, 352.Thiocyanic acid, potassium salt,stability of solutions of, 481.Thiocystis, nutrition and metabolismof, 432.Thiophen, tetraiodo-, reduction of,with aluminium amalgam, 343.Thiophosphoryl bromide, crystalstructure of, 180.Thiosulphates.Bee under Sulphur.Thorium dioxide, determination of,in monazite sand, 479.Threonine, isolation of, from proteins,311.Thulium, magnetic properties of, 126.Tigloidine, 358.Tilasite, crystal structure of, 166.Tin, detection of, 490.Tin tetrabenzyl, decomposition of,269.Titanite, 165.Titanium, determination of, in rocks,475.Titanium Tonoxide, 150.Tobacco alkaloids, 358.structure of, 353.synthesis of, 356.deuteron bombardment of, 15.crystal structure of, 161.mosaic virus, aucuba-like, 43 1.inactivation of, 428.isolation and nature of, 426.ring spot virus, 431.a- and ,&Tocopherols, 410.Tolan, crystal structure of, 187.oxidation of, to benzil, 241.structure of, 203.Toluene, benzoylation of, with cata-lysts, 253.Tomato mosaic virus, 431.Toxicarol, constitution of, 346.apoToxicarol, 347.Trentepohbia, constituents of, 453.Trideuteroacetic acid, deuterium andsodium salts, electrolysis of, inwater, 114.Trideuteroammonia, photo-decom-position of, 68.Trideuterophosphine, photo-decom-position of, 69.Triethylamine, reactions of, withesters, 52.Trimethyl B-methylglycuronide,structure of, 297.Trioxymethylene, crystal structureof, 183.Tripep tides, synthetic , enzymichydrolysis of, 310.refractive index of, 39.Triphenylme thy 1, 2 82.Triterpenes, 327.Tri thio f ormaldehyde, crys t a1 s truc -turs of, 183.a- and P-Tritisterols, 411.Tritium, 42.Tropane bases, 358.Trouton's rule, 81.Trypanosomiasis, 423.Tuberculosis, pulmonary, vitamin4deficiency in, 407.Tudaramine, structure of, 360.Tungsten, detection of, microchemic-ally, 484.dehydrogenation of, 329.Umbilical cord, polysaccharide from,n-Undecanediamidine, trypanocidalUnsaturation, determination of, 221,Uranium, neutron bombardment of,Urea, denaturation of proteins by,Urine, determination in, of vitamin-nature of reducing substance in,acetylation of, 298.296.action of, 424.242.16.308.B,, 401.405.Uronic acids, 296.Valency, anomalous, in rare-earthelements, 122.Valentinite, crystal structure of, 160,180.isovaleraldehyde, photo-decomposi-tion of, 55.Valeroidine, 358.VaZonia uentricosa, cell-wall celluloseof, 453.Vanadium, determination of, inrocks, 477.Vapour pressure of solutions, deter-mination of, 99.Verbenaloside, fission of, by Asper-g i l l u s niger, 448.$-Verdoporphyrin, 380.Vesuvianite, 165.Vetivazulene, 394.Virus, plant.See Plant viruses,Viscosity of liquids, 81.Vitamins, 399.Vitamin-A, content of, in humanliver, 400.crystalline, from fish-liver oils, 399.deficiency of, in relation to deaf-ness, 400.synthesis of, 399.Vitamin-& 400INDEX OF SUBJECTS. 533Vi t amin-B 3 5 2.determination of, 402.in bread, 414.See also Aneurin.Vitamin-B,, 403.Vitamin-B,, 403.Vitamin-C, 404.determination of, 405.requirement of, for man, 406.See also Ascorbic acid.mode of action of, 410.See also Calciferol.Vitamin-D, 409.Vitamin-D,, 409.Vitamin-D,, 409.Vitamin-D,, 409.Vitamin-E, 410.Vitellomucoid, 295.Vitreous humour, polysaccharidefrom, 296.Volume, atomic, of rare earths,124.effects of deficiency of, 412.free, of liquids, 79.Vomicidine, 367.Vomicine, structure of, 367.Water, determination of, in minerals,474.dissociation constant of, 103.heavy. See Deuterium oxide.isotopic forms of, 42.isotopic composition of, and over-voltage, 109.Water, Raman spectrum and struc-Wheat germ oil, tocopherols from,\Vollastoriite, 165.Wool, composition and structure of,ture of, 90.410.structure of, 173.321.Xanthotoxin, 345.Xanthotoxol, 345.n- and aZZo-Xanthoxyletins, 345.Xanthoxylum americanurn, bark of,Xant hylet in, 345.Xenon, isotopes, 8.345.Ytterbium, magnetic properties of.Ytterbous sulphate, eIectrolytic127.preparation of, 130.Zinc, determination of, in rocks, 479.in nutrition of moulds, 443.neutron bombardment of, 17.Zinc bromate hemhydrate, crystalores, determination in, of fluorine,sulphide, action of light on, 74.structure of, 167.476.Zirconium, determination of, in rocks,476

ISSN:0365-6217    

DOI:10.1039/AR9373400517

出版商:RSC    

年代:1937

数据来源: RSC