British Chemical Abstracts. A. Pure Chemistry, July

BRITISH CHEMICAL ABSTRACTS

A .-P U R E CHEMISTRY

JU LY , 1927.

General, Physical, and Inorganic Chemistry.

Orbits and light-radiation of hydrogen elec­

trons. T. En gs e t (Ann. Physik, 1927, [iv], 82, 1017— 1024).— An extension of earlier theoretical work (this vol., 181). R. A. Mo r t o n.

Reversibility o f spectral lines. M. Ki m u r a

(Japan. J. Phys., 1927, 4, 75— 80).— From a re­

view of the known reversals occurring in the spectra of magnesium, calcium, zinc, cadmium, mercury, aluminium, thallium, and indium, it is shown that in the non-luminous vapours of these metals lower members of the spectral series are most easily absorbed, whilst higher members are more easily absorbed in the vapour produced by a spark discharge under water. The hypothesis that an electric field increases the probability of a large orbital transition and decreases that of a small one is advanced to interpret these results. It involves the conclusion that the order of reversibility of series lines depends on the intensity of the electric field in which the absorbing atom is placed. Confirmatory evidence is cited from data on the reversibility of lines in the heavy-current arc spectra of aluminium and thallium. R . W . Lunt.

Ratio of the numbers of resonating electrons for the potassium doublets. V. K . Pr o k o f i e v

(Phil. Mag., 1927, [vii], 3, 1010— 1025).— It has been shown, from measurements of the dispersion of potassium vapour in the regions of the first and second doublets of the principal series, that the ratio of the numbers of resonating electrons corresponding with the two doublets is 110 :1, and is independent of the density of the vapour. The corresponding measurements of this ratio for the individual lines of each doublet are 1-995 for the red and 2-046 for the violet doublet. These results are 20— 50% lower than those obtained by Bevan (A., 1911, ii, 349) and by Baxter (Phil. Mag., 1921, [vi], 42, 289), and it is suggested that these observers worked at greater distances than has the author from the absorption lines, which are outside the absorption bands always seen in the red end of the spectrum at high vapour density. A. E. Mi t c h e l l.

Multiplets in three-electron systems of the first long period. R. C. Gi b b s and H. E. W h i t e

(Physical Rev., 1927, [ii], 29, 655— 662).— The triad of multiplets of V in designated iF i

__A ]? ' ‘ ----I * t-i A r\

2.3.4-5

' 2.3.4. 5 3 . 4 . 5 - 6 ’ - 2.3.4- 5 > a n -d P2. 3. 4 .5 -® 1 ,2 .3 .4 an< J

multiplet i , 2 . 3 . 4 , 5 — 4 - f 1 2 . 3 . 4 . 5 have been identified.

In the V in multiplets, the initial state is given by one 4p electron and two 3d electrons ; in the final state, one electron is in a 4s orbit and the other two are m 3d orbits. A comparison of the data for one-,

two-, and three-electron systems of scandium, titan­

ium, and vanadium shows that the addition of first one and then a second d electron causes, not only an increase in the multiplicity, but also successive shifts in the radiated lines towards the longer wave-lengths by approximately the same frequency interval.

A. A. El d r i d g e.

Line absorption spectra of the alkaline-earth elements. 0 . H. Wa l t e r s and S. Ba r r a t t (Phil.

Mag., 1927, [vii], 3, 991— 993).— Observations of the line absorption spectra of the vapours of calcium, strontium, barium, and magnesium show the possi­

bility of transitions of the series electron from its normal IS orbit to orbits of the P , p 2, D, and F types. The transition to a D orbit has been observed in calcium and strontium vapours. Transition to an F orbit has been found in barium vapour. It is thus evident that the selection rule of unit change in azimuthal quantum number does not hold, and that changes of 2 and 3 occur in the absence of any applied field. Theseries IS —711P is the most readily absorbed.

The widths of these lines are sensitive to the partial pressure of the metal vapour, the behaviour being analogous to that of the corresponding series of the alkali metals. The 1 s —mpz and the 1 S ~ tnD lines are weakly absorbed, and their observation is diffi­

cult. Only the first three members of the 1 s—viF series of barium are strongly in evidence.

A. E . Mi t c h e l l.

Screening constants from optical data. O.

La p o r t e (Physical Rev., 1927, [ii], 29, 650— 654).—

The screening constants of copper, rhodium, palladium, and gold, computed from the optical data, are in agreement with those obtained from X -ray data.

A. A. El d r i d g e.

Line absorption of the non-luminous vapours of selenium and tellurium. M. Ki m u r a (Japan.

J. Phys., 1927, 4, 81— 84).— The spectrum obtained by filling a small cavity in the anode of a carbon arc (40 amp.) with selenium or tellurium has been examined; it is found that the group of lines I960, 2040, 2063, 2075 are self-reversed for selenium, and 20S1, 2143, 2147, 2209, 2259, 2383, 2386 A. for tellurium. The cadmium line 2259 is absorbed by tellurium vapour at 1600° (presumed to contain some monatomic tellurium); so also at 2143 is the wing of the fine 2144 broadened b y a condensed discharge;

it is therefore concluded that tellurium vapour absorbs the lines 2259 and 2143. Similar observations on selenium vapour showed that it absorbs the lines 1960 and 2040, and it is thought that the former can be identified with the 1<S— 2P line. R . W . Lu n t.

r r 601

602 BRITISH CHEMICAL ABSTRACTS.— A .

Large displacements and broadening of the lines of bromine and iodine. K. A s a g o e (Japan.

J. Phys., 1927, 4, 85— 102),—The broadening and displacement of a number of lines of the spectra of bromine and iodine have been determined in the range 6500— 2270 A. as functions of the pressure of the vapour and the current density. The displace­

ment increases as these two factors increase, the largest amount recorded being 2 A. The modes of broadening can be classified into three types as ■with chlorine (this vol., 2). R. W. Lunt.

Secondary radiation and polarisation of reson­

ance radiation in cadmium. W. A. M a c N a i k

(Physical Rev., 1927, [ii], 29, 677— 682).— When cadmium vapour containing a trace of mercury is illuminated by light of wave-length 2288 A., only the cadmium line 2288 A. appears in the secondary radiation if the vapour is stagnant, but if the metal is distilling, the mercury line 2536-7 A. and the cadmium lines 2288 and 3261 A , appear. It is sug­

gested that unstable molecules of CdHg are present in the distilling vapour. In order to account for the polarisation (35%) of the cadmium resonance radi­

ation (3261 A.) in zero magnetic field, it is necessary to assign effective radii to the colliding atoms which are 30 times as great, as the radii effective in ordinary collisions. A. A. E l d r i d g e .

Stages in the excitation of the spectrum of indium. J . G. F r a y n e and C. W . J a r v i s (Physical Rev., 1927, [ii], 29, 673— 676).— Electronic excitation of indium vapour gave the following lines (A.) : 3-3 volts, 4511-31,4101-76; 4-2 volts, 3258-56, 3039-35 in addition; 6-9 volts, 3051-19, 2957-01, 2932-63, 285S-30, 2836-91, 2775-35, 2753-88 in addition;

13-2 volts, 2710-26, 260P75, 2560-15, 2523-OS, 2306-07 in addition. The resonance lines were less intense than the corresponding lines due to the mete- stable atoms. A. A. El d r i d g e.

Structure of the La n spectrum. W. F.

Me g g e r s (J. Opt. Soc. Amer., 1927, 14, 191—204).—

Existing data on the spark spectrum of lanthanum have been correlated and a system of terms has been applied covering many of the observations.

L. F. Gi l b e r t.

New lines in the arc spectrum of gadolinium between 3100 and 2200

A.

(Anal. Fis. Quim., 1927, 25, 90— 93).— Data are given for 250 new lines between 3064-9 and 2217 A.

in the arc spectrum of gadolinium at normal pressure.

G . W . Ro b i n s o n.

Possible abnormal spectral series of mercury.

R. G. Lo y a r t b and A. T. Wi l l i a m s (Physikal. Z., 1927,2 8 ,383— 3S7).— Investigations on the excitation potentials of mercury atoms have disclosed a constant difference of 1-4 volts (Franck and Einsporn, Z.

Physik, 1920, 2, 18; Loyarte, A., 1926, 1073). The regularity can be explained spectroscopically by the assumption of an abnormal arc spectrum for the mercury atom, based on a deep 1 S' term 174,940 1, combining with terms of the form where x may be F P 2, F P v l^PQ, and 1P15 n 1, 2, 3, 4, 5, 6, or 7, and At> a displacement constant corresponding with 1-4 volt«. Mercury vapour excited by means of electron impacts has been examined spectroscopic­

ally. In addition to other lines (normal triplet series etc.), abnormal lines at 2045 and 1973, design­

ated l 1/®—a3i V , V S —aPPj}, are disclosed, and it is thought very probable that they are the first terms of two abnormal mercury series. R. A. Mo r t o n.

Broadening of the mercury resonance line by the addition of foreign gases. W. Or t h m a n n

and P . Pr i n g s h e i m (Z. Physik, 1927, 43, 9— 15).—

By the addition of foreign gases, the breadth of the absorption line corresponding with the resonance radiation of mercury vapour becomes 2-5 times the normal Doppler breadth. The line-breadth of the resonance radiation has been shown by absorption measurements to be the same for broadened and unbroadened primary radiation. This result is discussed theoretically (cf. A., 1926, 224).

R . A. Mo r t o n.

Modified scattered A'-radiation due to super­

position. C. G. Ba r k l a (Nature, 1927, 119, 778— 779).— Systematic examination of the radiation scattered from various thicknesses of scattering sub­

stance shows that a perfectly regular development of the modified scattered radiation can be traced to the superposition of unmodified radiation from thin

layers. A. A. El d r i d g e.

Soft A'-ray spectra. T. H. Os g o o d (Nature, 1927, 119, 817).— Using the anti-cathode of an X-ray tube as a source of radiation, and a concave glass grating mounted at a large angle of incidence, some 15 lines between 40 and 200 A. have been photo­

graphed. Strontium, barium, and platinum are possible causes of the observed spectra. The most prominent of the lines which have been fitted into the scheme of X-ray levels is the M It u doublet of strontium (159, 160-1 A.). The ’ spectrum of aluminium contains a kind of band with sharp limit at 166-6 A., shading off towards the longer wave­

lengths. A. A. El d r i d g e.

A'-Ray isochromats of copper taken in different directions relative to the cathode stream. W. W.

N i c h o l a s (Physical Rev., 1927, [ii], 29, 619— 631)-—

Measurements of the variation with potential of the intensity of monochromatic X-rays of wave-lengths 0-823— 0-247 A. for directions making angles of 36°, 90°, and 144° with the cathode stream show that an isochromat of frequency v is linear from [5j4H)v to 2Hv, where Hv is the quantum voltage for excit­

ation of frequency v. The intercepts on the intensity axis at Hv are tabulated. The energy distribution in the X-ray continuous spectrum from a thick and a thin target, respectively, is investigated.

A. A. E l d r i d g e .

Selective displacement o f 0 0153 A . in X-ray spectral lines. V and VI. F. H. Lo r in c, (Chem.

News, 1927, 134, 291— 292, 321— 322; cf. this vol., 391).— Y. A new method is given for the derivation of the displacement value based on the relationship of Ay to AH#.

VI. The inter-relationships between the displace­

ment value and various constants is further dis­

cussed. The question of the absolute constancy of the Planck, Rydberg, and other constants is raised.

R . A. Mo r t o n.

GENERAL, PHYSICAL, AND INOEGANIC CHEMISTRY. 603

Precision measurements of the Jt-series of molybdenum and iron. A. La r s s o n (Phil. Mag., 1927, [vii], 3, 1136— 1160).— A detailed description is given of a precision spectrograph intended for wave­

length measurements over the range 0-4— 2-5 A.

The method of measurement is described, and the results of measurements of the iT-series of iron and molybdenum are given. Absolute measurements in the first order gave for molybdenum for the wave­

lengths of Koij and K $ v the values of 0-707831 and 0-630978 A., respectively. The corresponding value for the line FeA’ aj was 1-932066 A. Relative measurements in the first order of the lines M o Z «,, MoA62, MoAS3, and FeA’ x2 gave the wave-lengths of 0-712089, 0-619698, 0-631579, and 1-935987 A., respectively. Relative measurements in the second order gave the wave-length of the line M oAa2 as 0-712115 A. Similar measurements in the third order gave the wave-lengths of the lines MoAa2 and MoAS3 as 0-712116 and 0-631547 A., respectively. The accuracy of the measurements is discussed, and the results are compared with those of other observers.

A. E. Mi t c h e l l.

Positions of the Ji-absorption limits of van­

adium in various of its compounds. S. B.

H e n d r i c k s and R. W . G. W y c k o f f (J. Physical Chem., 1927, 31, 703— 712).— Data for the A-absorp- tion limits of vanadium in many of its compounds are given and discussed. The lower the valency the longer, in general, are the wave-lengths of the absorp­

tion edges. Pronounced variations occur in com ­ pounds of the same valency type, and the positions of the absorption edges depend on factors other than the numerical value of the valency. These factors are briefly discussed. L. S. T h e o b a l d .

Theory of the Compton effect. G. We n t z e l

(Z. Physik, 1927, 43. 1— 8).— The Compton effect has hitherto been studied by means of the wave mechanics only for the limiting case of free-electron scattering. A theory applicable to weakly-bound electron scattering has now been developed which shows satisfactory agreement with experiment.

R. A. Mo r t o n.

Photo-electric threshold fo r germanium. G . B . W e lc h (J . Opt. Soc. Amer., 1927, 14, 233).—Germ­

anium was exposed to monochromatic radiations of measured intensities in the range 2550— 2375 A., and the consequent, photo-currents were determined.

Extrapolation of the curve formed by plotting currents per unit intensity of radiation against the wave­

lengths used until it cuts the wave-length axis give the photo-electric threshold of germanium as probably 2590—25 A. L. F. G i l b e r t .

Changes in the photo-electric threshold of mercury. H. K. D u n n (Physical Rev.. 1927, [iij- 2S. 693— 700).— Kazda’s value (2735 A .; A., 1926,3) for the long wave-length limit of the flowing surface of mercury is confirmed. Hydrogen in con­

tact with the surface does not change the photo­

metric behaviour, but when the mercury is con- censed in presence of hydrogen the variations in the photo-electric threshold in a high vacuum caused by some impurity are greatly impeded by the dissolved

£as- A. A. E l d r i d g e . -

Thermionic emission from iron-alkali m ix­

tures used as catalysts in the synthesis of ammonia. C. H. Ku n s j i a n (J. Franklin Inst., 1927, 203, 635— 646).— A convenient source of posi­

tive ions of the alkali and alkaline-earth metals is desci'ibed. Fused artificial magnetite with 1% of aluminium oxide and 1% of the desired alkali or alkaline-earth oxide are placed on a platinum strip, mounted in a vacuum tube, and reduced. The result­

ing metal mixture forms a plentiful source of positive ions. The emission consists of single positively- charged ions, no joined atoms being detected in any case. In contrast to ions obtained from thin con­

densed films, the source is free from any marked change in the temperature of the surface. The positive and negative equivalent work functions are determined, and the mechanism of the emission is discussed. Finally, the bearing of the foregoing on the increased catalytic activity of an iron-alumin- ium-alkali mixture over a plain iron catalyst for the ammonia reaction is discussed. W . E. Do w n e y.

Electrons [as a] gas. T. d e Do n d e r (Bull.

Acad. roy. Belg., 1926, [v], 12, 854— 855).— It is suggested that for purposes of the study of super­

conductivity, “ electron gas ” should be considered as a van der Waals gas. Taking Tc as 8°, calculation gives a = 5 -1 5 x l0 * 4 and 6 = r 2 5 x l 0 ~ 10 c.g.s.u.

C. W . Gi b b y.

Electron stream and space charge in dense gases. F. Sk a u p y and W . Da u d t (Physikal. Z., 1927, 28, 313— 315).

Number of detachable electrons in various elements. M. Ki m c r a (Japan. J. Phys., 1927, 4, 71— 74).— The number of easily detachable electrons of a number of elements, the enhanced spectra of which have been classified by the author (A., 1925, ii, 726), has been estimated by making use of the Bohr interpretation that arc, spark, and super-spark spectra are to bo associated with orbital transitions of neutral, singly-, and doubly-charged atoms, respectively. This number increases with the positive valency of the element, and rises to a maximum in groups IV and V. It is concluded that this number increases with the number of electrons in the highest

?i1-orbit, and that the presence of electrons in the

« 2-orbit protects the electrons in the former orbit from

being detached. R. W . Lu n t.

Mechanism of [electron] emission from oxide [coated] cathodes. W. Es p e (Wiss. Veroff. Siemens- Konz., 1927, 5, 29— 45).— The effect of time, temper­

ature, and anode voltage on the electron emission from cathodes coated with oxides of barium, stron­

tium, or calcium is investigated. It is concluded that the oxide layer is electrolysed b y the initial small emission current, with the formation of emission centres composed of the free alkaline-earth metal.

This also diffuses to the surface. The lack of satur­

ation, characteristic of these cathodes, is attributed to the effect of the anode voltage, which increases the electrolysis and raises the temperature of the cathode.

It is not considered that residual gases play an important part. For a constant chemical state, the emission-temperature relation follows Richardson's equation. The constant -4 in this equation is deter-

604 BRITISH CHEMICAL ABSTRACTS.---- A .

mined by the chemical state, but the work function B is unaffected. Any cause which aids the formation of the emission surface increases A and improves the emission. Evaporation and oxidation which destroy the emission centres lower the value of A and decrease the emission. C. J. Sm i t h e l l s.

Work function for cathodes coated with alkaline-earth oxides. W . E s p e (Wiss. Verôff.

Siemens-Konz., 1927, 5, 46— 61).— The emission from oxide-coated cathodes is measured at different temper­

atures and the work function calculated from the results, both for the V T~ and for the T-~ law. The values (in degrees Abs. and volts, respectively), obtained from Richardson’s equation are for cal­

cium oxide 22,400+300°, l-93±0-03 ; for strontium oxide 16,600 ^250°, l-93+ 0'02 ; for barium oxide 12,900±250°, 1 11¿0 -0 2 . The values from Dush- man’s equation are 20,500+300°, 1-77 ¿0 -0 3 ; 14,7504;

300°, l-2 7 ± 0 0 2 5 ; and ll-5 0 0 ±3 0 0 °, 0-99±0-03, respectively. C. J. S m i t h e l l s .

Influence of the physical and chemical con­

stitution of resistance cellules on the intensity of the radiation which they emit. G . Re b o u l,

G. Dé c h è n e, and R . Ja c q u e s s o n (J . Phys. Radium, 1927, [vi], 8, 199— 214).— Compressed pastilles of inorganic salts connected to a P.D . of a few hundred volts emit short-wave radiations in the region 40—

300 Â., the intensity of which can be measured by determining the state of ionisation of the gas in the neighbourhood of one or other of the electrodes.

The change in ionisation brought about by changing the chemical constitution or the physical condition of the pastilles has been studied. The emission of short-wave radiation depends on the occurrence of voltage discontinuities near the electrodes. Any physical change likely to influence the cohesion of the particles making up the pastille would be expected to show itself in the intensity of emission. This general idea of the process has been confirmed by detailed investigations of the influence of time, of fatigue in the pastilles, and of the previous history, grain size, moisture content, and degree of compression of the preparation used. The physical factor is of such preponderating importance that no clearly-defined relationship emerges between chemical constitution and intensity of emission. A physical mechanism of the phenomena is suggested which is in accord with the data on the effect of varying the physical con­

ditions (cf. Bodin, this vol., 289). R . A. Mo r t o n.

Chemical activation by collisions. R. C . To l m a n, D . M . Yo s t, and R. G. Di c k i n s o n (Proc.

Nat. Acad. Sci., 1927, 13, 188— 192).— Since in the great majority of activating collisions the total energy available is only slightly greater than that necessary for activation, the assumption of Fowler and Rideal (this vol., 114) that activation occurs at every collision where the total available energy is sufficient for the purpose, involves the further, apparently improbable, assumption that practically all the energy can flow into one of the two molecules. Another serious difiiculty which the theory encounters is that it involves diameters for deactivational collisions which ate inconveniently large. J. S. Ca r t e r.

Ionisation by collisions of the second kind in the rare gases. G. P. H a r n w e l l (Physical R ev., 1927, [ii], 29, 683— 692).— In a mixture of helium and neon (50%) ionised by electron impact the ratio He+/Ne+ decreases regularly between 0-03 and O'15 mm. The probable reaction is Ne-j-He+— >-Ne++He.

With a mixture of neon and argon (50%), the regular decrease in the ratio N e+/A+ between0-05 and 0-15 mm.

waslessrapid; A + N e +— ->Af -fN e. W itham ixture of helium and argon (50%), the ratio H e+/A+ was constant; using 85% of argon, the ratio decreased slightly. Presumablythe reaction is A + H e + — ->A++

He. The effects are ascribed to a type of collision of the second kind equivalent to ionisation by positive

ions. A. A. E l d r i d g e .

Simultaneous ionisation and excitation by foreign ions in a gaseous mixture. O. S . Du f f e n- d a c k and H. L. Sm i t h (Nature, 1927,119, 743— 744).

— Experiments with mixtures of carbon monoxide and of nitrogen with argon, neon, and helium indicate that an ion of one kind may, on collision with a molecule of another gas, ionise that molecule and excite the resulting ion to the degree that the energy required to ionise the one exceeds the energy required to ionise the other. The results support Duffendack and F ox’s assignment (A., 1926, 777) of the Baldet- Johnson bands. A. A. El d r i d g e.

Ionisation processes in hydrogen and nitrogen.

H. K a l l m a n n and M. A. Bredig (Z. Physik, 1927, 43,16— 27).— H + ions originate at the same ionisation potential as H ,+ ions, and the ratio of intensities is approximately independent of electron energy. The assumption that the H + ions arise from thermal dissociation of H2+ ions leads to a low value for the heat of ionisation of hydrogen. The discrepancy may possibly be explained by the formation of H + ions as a result of chemical change of the H2+ ions in the gas space, or else by a greater electrical acceleration of these ions. No primary ionisation into atoms has been detected for nitrogen or hydrogen. Provided the kinetic energy is not considerably in excess of the dissociation energy, the number of atom-ions formed as a result of accelerating the molecular ions is very small. Ions of apparent mass ¿H and |N originate from molecule-ions which have passed through the electric field (cf. A., 1926, 104).

R. A. Mo r t o n.

Ionisation by bubbling air through solutions.

C. R. P i t t s (J. Physical Chem., 1927, 31, 693— 702).—

The ratio of the number of positive ions to that of negative ions liberated when air is bubbled through aqueous solutions of many salts has been measured.

The ratio may be greater or less than unity for a particular solution, but in every case examined it is greater than the ratio obtained with distilled water.

The ratio depends to a small extent on the time of bubbling, and on the concentration of the solution.

With an aqueous solution of sodium chloride, the ratio first of all decreases, then increases to a maximum at a mol. fraction of 10%, and finally decreases up to a mol. fraction of 25% . When air is bubbled through distilled water, both positive and negative ions are liberated, the latter in excess.

L. S . Th e o b a l d.

GENERAL, PH YSICAL, A N D INORGANIC CHEMISTRY. 605

Gaseous explosions. II. Ionisation in deton­

ating and non-detonating mixtures of hydrogen and oxygen. S . W . Sa u n d e r s (Trans. Faraday Soc., 1927, 23, 242— 248; cf., A., 1926, 689).— The ionisation, produced when mixtures of hydrogen and oxygen are exploded in a spherical bomb has been studied by measurements of the currents between parallel electrodes placed at its centre, using an Einthoven galvanometer. The mixtures were sparked at the ends of firing tubes of different lengths which were attached to the bomb. It was found that the currents increased linearly with increasing length of the firing tube, and that the slopes of these lines, and also the magnitude of the current for zero length of firing tube, were greatest for a mixture of the composition 2H2+ 0 2. These results are ex­

plained in terms of the changes in temperature of explosion caused by the turbulence set up in the bomb by expulsion of gases from the firing tubes. When the mixtures were sparked near the surface of the bomb, the currents were diminished by the addition of “ anti-knocks ” and increased by the addition of

“ knock-inducers.” The variation of current with length of firing tube is, however, not affected by

“ anti-knocks ” when the mixtures do not detonate, or by “ knock-inducers ” when the mixtures are already detonating. • G. A. El l i o t t.

Gaseous explosions. III. Ionisation in ex­

plosions of carbon monoxide and oxygen. S. W .

Sa u n d e r s and K. Sa t o (Trans. Faraday Soc., 1927, 23, 248— 256; cf. preceding abstract).— The elec­

trical conductivity of mixtures of dry carbon monoxide and oxygen exploded in a spherical bomb is greatest for a mixture of composition 2C0 + 0 2, and the variation of conductivity with composition confirms the view that ionisation in gaseous explosions is mainly thermal. In presence of hydrogen or water, when the velocity of the explosion wave is increased, there is a corresponding increase in the ionisation produced on explosion, whilst dry mixtures contain­

ing no hydrogen, for which the development of pressure during explosion is slow, exhibit a corre­

sponding increased duration of ionisation.

G. A. El l i o t t.

Gaseous explosions. IV. Ionisation in methane-oxygen and acetylene-oxygen m ix­

tures. S . W . Sa u n d e r s (Trans. Faraday Soc., 1927, 23, 256— 266; cf. preceding abstracts).— Maxi­

mum conductivity is attained when mixtures of methane and oxygen are exploded to form water and carbon dioxide, or when mixtures of acetylene and oxygen are burnt to water and carbon monoxide.

The addition of 70% of nitrogen to the acetylene- oxygen mixtures, however, lowers the maximum temperature of explosion so that combustion of carbon monoxide to dioxide occurs in the mixture which gives maximum conductivity. The ionisation 1 j thermal in character and is probably not related to

the ignition temperature of the initial mixture.

G. A. El l i o t t.

Electrodeless discharge and active nitrogen.

870— 8-m S (5,u11- A ca d ' r° y - B elg-> 1 9 2 6 ’ M > 1 2 >

i T ''—’The electrical conductivity of nitrogen as “een measured during the luminescence produced

by an electrodeless discharge. In addition to the usual luminescence, a very brief green glow was observed to continue after the cessation of the discharge at pressures between 2 and 10 mm. It is shown that the ionisation current follows the same variations, as a function of the pressure, as the intensity of the luminescence, and that the latter is not directly connected with the magnitude of the ionisation current (cf. Thomson, A., 1926, 988).

Hysteresis is found in the relation between the ionis­

ation current and that in the primary of the exciting coil. The roles of pressure and of the nature and frequency of the discharge are discussed.

C . W . Gi b b y.

Continuous spectra obtained by the electrode­

less discharge in mercury vapour. G . Ba l a s s e

(Compt. rend., 1927, 184, 1320— 1322).— Two con­

tinuous spectra have been obtained b y electrodeless discharges in mercury vapour at constant temperatures and the results correlated with those of Bloch for the fractionated spark spectra of mercury (A., 1923, ii, 350). The passage from a state of ionisation £ p + l) to a state of ionisation p is accompanied by the emission of a continuous spectrum (this vol., 490).

J. Gr a n t.

General characteristics of electrically exploded wires. J. A . An d e r s o n and S . Sm i t h (Astrophys.

J., 1926, 64,295— 314).— A discussion of experimental procedure and probable mechanism.

Ch e m i c a l Ab s t r a c t s.

Diffraction of cathode rays by a thin [celluloid]

film. G . P. Th o m s o n and A. Re i d (Nature, 1927, 119, S90).

Velocity selector for atomic rays. J. Ty k o- c i n s k i- Ty k o c i n e r (J. Opt. Soc. Amer., 1927, 14, 423— 430).— Theoretical. The theory of an apparatus for selecting atoms of particular velocities from atomic and molecular rays is given. The character­

istics of the expected spectrum-like images are

discussed. W . E. Do w n e y.

Radioactivity in the environs of the pitchblende mines of St. Joachimsthal, Czechoslovakia. F.

Be h o u n e k (Physikal. Z., 1927, 28, 333— 342).— The radioactivities of spring water, the soil, the air, and the air of mines have been determined at various points near the mines. The effects are found to be extremely local. R . A. Mo r t o n.

Radioactivity of lead exposed for a long period to solar radiation. (Ml l e.) S . Ma r a c i n e a n u

(Compt. rend., 1927, 184, 1322— 1324; cf. A., 1926, 6, 879).— Determination by an electrometer of the radiations from the lead roof of the Paris Observatory, at all hours of the day and in all weathers, indicates the existence of radioactivity consisting chiefly of a-particles with probably some penetrating rays of low intensity. This radioactivity is found to be stimulated b y sunlight. H. De s l a n d r e s (Compt.

rend., 1927, 184, 1324— 1325) appeals for specimens of lead which have been insolated for long periods to further these experiments. J. Gr a n t.

Grouping of atoms of radioactive elements in mercury. (Ml l e.) C. Ch a m i e (Compt. rend., 1927, 184, 1243— 1245).— The effects on a photographic

606 BRITISH CHEMICAL ABSTRACTS.---- A .

plate of distilled mercury containing small quantities of platinum and radiothorium have been determined.

Well-defined, circular, star-shaped images were obtained similar to those produced directly by a radio­

active element. There was evidence of the presence of the radioactive substances in small groups of atoms of diameters of the order of a micron, the photo­

graphic effect being due to the emission of a-particles.

J . Gr a n t.

Heat of radiation of radiothorium. A Do r a­ b i a l s k a and D . K. Jo w a n o w i c z (Rocz. Chem., 1927, 7, 23— 29).— The heat produced by the [3-, and y-radiations from radiothorium enclosed in cylin­

drical screens of various thicknesses of aluminium, copper, and lead for a quantity of radiothorium the y-radiation of which is equivalent to that of 289-5 mg.

of radium, is (in g.-cal. per hour) 58 for a-, and 8-2 for (5-radiation. The average absorption coefficient for the ¡3-radiation of radiothorium in aluminium is 38-3 cm."1 The ratio of the heat of radiation to the intensity of y-radiation is 60% greater for radio- thorium than for radium. R. Tr u s z k o w s k i.

Vaporisation of polonium. P. Bo n e t-Ma u r y

(Compt. rend., 1927, 184, 1376— 1378).— When a deposit of polonium is maintained electrically at 400°

in a vacuum, the polonium vaporised may be con­

densed quantitatively on the outside of a thin copper cylinder containing liquid air and placed at a distance from the deposit less than the mean free path of polonium. Tho polonium atoms travel in straight lines, and are retained b y the copper at the points on which they strike it. From measurements of the activity, the distribution of the atoms on the copper was determined, and Lambert’s cosine law, that the number of atoms vaporised in an infinitely small solid angle is proportional to the cosine of the angle between the axis of the solid angle and the normal to the surface of emission, was confirmed.

J . Gr a n t.

Effect of the orbital velocity of the electrons in heavy atoms on their stopping power for a- particles. L. H. Th o m a s (Proc. Camb. Phil. Soc., 1927, 23, 713— 716).— Theoretical. The stopping powers of neon, argon, krypton, and xenon have been calculated. The electrons are supposed to be moving in orbits; collisions are treated as in Henderson’s theory, but, in addition, the speed of the electron in its orbit is taken into account. The values calculated are in fair agreement with those determined experimentally. W . E. Do w n e y.

Stopping power of hydrogen atoms for a- particles according to the new quantum theory.

J. A. Ga u n t (Proc. Camb. Phil. Soc., 1927, 23, 732—

754).—Mathematical. The a-particle is represented by a point moving with constant velocity in a straight line and forming the centre of a Coulomb field. The effect on the atom is found by perturbation theory.

It is deduced on the new quantum theory, as on the classical theory, that there is an average transfer of energy from the a-particle to atoms at all distances, and of nearly the classical amount. The difficulties in the theory of the stopping of a-particles, therefore, are no longer fundamental, as in the old quantum

theory. W . E. Do w n e y.

Absolute intensities of the y-rays of radium-/?

and -C. C. D. E l l i s and W . A. W o o s t e r (Proc.

Camb. Phil. Soc., 1927, 23, 717— 729).— Theoretical.

It is shown that the heating effect of the y-rays, the total number of quanta emitted, and the intensities of the ß-ray groups may all be correlated in terms of the absolute intensities of the y-rays. This correl­

ation depends only on the value and rate of variation with frequency of the internal conversion coefficient of the y-rays, and once this has been ascertained, the intensities of the y-rays follow at once from the intensities of the ß-ray groups. Determination of this conversion coefficient would settle whether continuous y-rays are emitted or not. A reasonable value for the conversion coefficient is deduced which accounts for the total energy of the y-rays, so that the evidence is against the existence of a continuous y-ray spectrum (A., 1925, ii, 923). W . E . D o w n e y .

Absorptive power of atom-nuclei for y-rays.

W. K u h n (Z. Physik, 1927, 43, 56— 65).— Theoretical.

Meitner’s ideas (A., 1926, 106) are extended, and it is concluded that marked selective absorption of y-rays, e.g., from thorium-C" by thorium-ft, is

probable. R. A . M o r t o n .

Transmutation of elements. L . T h o m a s s e n

(Nature, 1927, 119, 813).— Smits and Karssen'a experiments (this vol., 87) on the spectroscopic behaviour of lead subjected to prolonged arc and spark discharge have been repeated, but the results have not been confirmed; the spectrum of the lead is unchanged. A. A . E l d r i d o e .

Transmutation of hydrogen into helium.

F. P a n e t h (Nature, 1927, 119, 706— 707).— See this vol., 429.

Structure of an atom of nitrogen. III. H.

Co l l i n s (C h e m . N e w s , 1927, 134, 369— 374).—

S p e c u la tiv e .

Spinning electron and wave mechanics. E.

G u t h (Nature, 1927, 119, 744).— Mathematical. An attempt to derive the assumption that the magnetic moment corresponding with the spinning movement of the electron is exactly twice as great as that of the revolving electric point-charge with the same mechanical angular momentum, from the relativistic Schrödinger wave equation in connexion with the electrodynamic meaning of the wave-function

A . A . El d r i d g e.

Unidirectional quanta in wave mechanics-

G . B r e i t (J. Opt. Soc. Amer., 1927,14, 374— 3S0).- Theoretical. The distribution of charge responsible for the emission is represented by a plane wave having the direction of the emitted quantum for it»

wave-normal and having the frequency and wave­

length of the normal. W . E . D o w n e y .

Wave theory of the electron. W. P. A l l i s

and H. M ü l l e r (J. Math. Pliys. Mass. Inst. Tech., 1927, 6, 119— 132).— The electron is regarded as a wave of frequency v= (m c2+eV)/h and wave number

¡i.=c(m2—m02)*/h, with which electricity is associated as energy is associated with an electromagnetic wave.

The velocity of the electron is given by the group velocity Sv/8(i. The quantum conditions are studied, with the result that a quantum jump is regarded as a

GENERAL, PHYSICAL, AND INORGANIC CHEMISTRY. 607

continuous process, with the charge passing gradually from the wave characteristic of the initial state to that corresponding with the final state. During the process, the waves form groups of velocity v—Av/Ajx.

The electron is thus conceived as a bundle of very slighty differing waves obeying electromagnetic laws.

The theory permits the Compton effect to be regarded as a Doppler effect. R. A. Mo r t o n.

Quantum mechanics and direction-degener- ation. J. R. Op p e n h e i m e r (Z. Physik, 1927, 43, 27— 46).— The quantum mechanics of the displace­

ments in degenerate systems are investigated in a simplified maimer, and the spontaneous radiation from such disturbed systems is calculated in terms of Dirac’s theory. The treatment allows several important rules, such as Heisenberg’s polarisation rules for resonance light, Skinner’s rules for impact emission, and Hanle’s rules for the effect of external fields, to be included as special cases of a wider theory. An explanation of the anomalous polar­

isation of the mercury resonance line is advanced.

R. A. Mo r t o n.

Scattering coefficient for short waves according to Schrodinger's theory. J. A. St r a t t o n (Physikal.

Z., 1927, 28, 316— 323).

Electronic states and band spectrum structure in diatomic molecules. IV. Hund's theory;

second positive nitrogen and Swan bands ; alternating intensities. R. S. Mu l l i k e n (Physical Rev., 1927, [ii], 29, 637— 649).— Practically all the available evidence supports Hund’s theory of molecular electronic states and band spectra. Hund’s interpretation of the second positive nitrogen bands as a 3P — >- 3P transition is extended to the Swan bands. The alternating intensities or alternate missing lines in the He2, N2> Swan, and N2+ bands are formally accounted for. The N H bands classed by Hulthen and Nakamura (this vol., 185) as 3P ---- >- lS are probably 3P — >■ 3S. A. A. El d r i d g e.

Bands in the extreme ultra-violet spectrum of a helium discharge. L. A. S o m m e r (Proc. Nat.

Acad. Sci., 1927, 13, 213— 216).— The helium line 600-3^0-6 A. is apparently in reality a band arising from a low-lying term in the spectrum of molecular helium corresponding with the fundamental term XS in the spectrum of atomic helium and having almost

the same term value. J. S. C a r t e r .

Structure of the ultra-violet absorption band of ozone. D. C h a l o n g e and M . L a m b r e y (Compt.

rend., 1927,184,1165— 1167).— The complete structure of the ultra-violet absorption spectrum of ozone has heen determined by the use of the continuous spec­

trum of hydrogen, and the results have been correlated with those obtained in the Shaver and Huggins regions. By means of the microphotometer, a series of undulations on the absorption graph, situated on an ascending curve, has been established, and the positions of their maxima have been determined.

J. Gr a n t.

Absorption spectra of gallium, indium, man­

ganese, chromium, nickel, and cobalt in under­

water sparks. A. W . Smith and M. M u s k a t

physical Rev., 1927, [ii], 29, 663— 672).— The

absorption lines found in the under-water spark spectra of indium and gallium, in agreement with observations in the vapour state, indicate that the normal state of the valency electron is the 2p state;

for manganese, the normal state of the valency electron is the 1-s sextet level. The assignment of lines and arrangement of terms with respect to the ground level given by Catalan (A., 1923, ii, 519) and Gieseler (A., 1924, ii, 285) for chromium, Bechert and Sommer (A., 1925, ii, 913, 1014) for nickel, and Catalan (A., 1925, ii, 611) for cobalt are verified.

A. A. El d r i d g e.

Absorption spectra and pleochroism of iodine and herapathite. P. Bovis (Compt. rend., 1927, 184, 1237— 1239).—The optical densities of layers 1 ¡x thick of iodine and herapathite have been deter­

mined, using natural and polarised light. In natural light, iodine and herapathite prepared according to the Baume and Zimmern-Coutin methods (A., 1926, 706) had almost the same opacities for a wave-length of 0-650 ¡X. The Baume herapathite had the most accentuated pleochroism, the Zimmern-Coutin pre­

paration behaving like a mixture of iodine and herapathite. Solid iodine gave a large absorption band at a wave-length of about 0-255 (x.

J. Gr a n t.

Bands in the absorption spectrum of mercury.

( L o r d ) R a y l e i g h (Nature, 1927, 119, 778).— Bands allied to, but not identical with, the emission bands previously observed from 3055 to 2697 A. (this vol., 496) have been obtained in absorption. Closer examination of the diffuse absorption bands at 2345, 2338, 2334, and 2339 A. shows that superposed on this structure is a much finer one of the order of 1 A. The lines 2270 and 2656 A. were not detected in absorption. A. A. E l d r i d g e .

Intensities of molecular beams. T. H. Jo h n­

s o n (Nature, 1927, 119, 745— 746).— When the

region between the two slits through which the beam of mercury molecules is passed (Knauer and Stern, this vol., 92) is surrounded by a surface cooled with liquid air, the intensity of the beam increases uni­

formly with the oven pressure between 0-1 and 30 mm.

A. A. El d r i d o e.

Effect of temperature on the refractive index of rock salt. (Si r) R . Ro b e r t s o n and J . J . F o x (Nature, 1927, 119, 818).— The acceptance of the 4-4 (x emission band of carbon dioxide or the quartz reflexion bands as bench marks is misleading unless combined with suitable temperature corrections of the prism used. A variation of 5° in the working temperature with rock salt or fluorite results in a difference of 0-075 [i in certain parts of the near infra-red. A. A. El d r i d g e.

Transformation spectra. E. L. Ni c h o l s, H . L.

Ho w e s, and D. T. Wi l b e r (J. Opt. Soc. Amer., 1927, 14, 205—222).— Lenard’s observations on the colours of molten beads of salts of the alkali metals (A., 1905, ii, 565) were confirmed and the temperatures at which the effects occur determined. Observations on 37 elements the salts of which cannot readily be obtained in the form of molten beads were made by introducing small quantities of their compounds into sodium phosphate or borax beads. Such beads

608 BRITISH CHEMICAL ABSTRACTS.---- A ,

when heated in a hydrogen flame underwent trans­

formations characterised by a sudden clouding or clearing at definite temperatures. These trans­

formations were marked by changes of brightness, and frequently by a characteristic colour which was present only during the transformation stage. The effects were reversible, i.e., could be observed either during the heating or the cooling of the beads. The transformation spectra of beads containing the rare earths correspond with those of the cathode fluorescence of the element. L. F. Gi l b e r t.

New infra-red absorption bands of methane.

J. W . El l is (Proc. Nat. Acad. Sci., 1927, 13, 202—

207).— Five new absorption maxima at 1-15, 1-37, 1-66, 1-72, and 1-80 ^ are reported. The combined data of Cooley (A., 1926, 659) and the author are tabulated and the observed bands identified hi terms of four fundamental frequencies. Chloroform ex­

hibits bands at 1-15, 1-40, and 1-69 ¡j.. The bands intimately associated with the carbon-hydrogen linking do not appear to constitute a single parabolic series, as was formerly supposed. Wave-length corrections to be applied to all the author’s previously published work (A., 1924, ii, 218, 219; 1926, 454, 883)

are given. j . S. C a r t e r .

Spectroscopic researches on aromatic amino- acids and their derivatives. E . Ab d e r h a l d e n

and R. Ha a s (Z. physiol. Chem., 1927,166, 78— 83).—

Absorption spectra for o- and m-hydroxyphenyl- alanines and tyrosine are closely alike, the curve for the mefo-compound lying between those for the ortho- and para-compounds. The main absorption band (i'=3580) is independent of the nitrogen, since it also appears in the spectra of glycyl-Z-tyrosine and tyrosine anhydride (3 : 6-di-p-hydroxybenzyl-2 : 5- diketopiperazine). In 0 - carbethoxy - N - formyl- tyrosine, the band shifts to 3740, from which it seems probable that in proteins the phenolic hydroxyl group of tyrosine is free. Absorption spectra for 3 : 5-dibromo- and 3 : 5-di-iodo-tyrosines and 3 : 6-di- (3 : 5-di-iodo-4-hydroxybenzyl)-2 : 5-diketopiperazine are given. Those of thyroxine and tryptophan are quite dissimilar, contrary to the statement of Hicks (A., 1925, ii, 473).

The preparation of 3 : 6-di-(3 : 5-di-iodo-4-hydroxy- benzyl)-2 : 5-diketopiperazine, decomp, about 204°, by the action of iodine on Z-tyrosine anhydride in alkaline

solution is described. C. Ho l l i n s.

Ultra-violet absorption spectra of cyclohexene, ethyl ether, methyl n-amyl ether, and ethylene- chlorohydrin. A. W . Sm i t h, C. S. Ad a m s, and C. S. Pe a s e (J. Amer. Chem. Soc., 1927, 49, 1335—

1346).— The ultra-violet absorption spectra of cyclo- hexene, ethyl ether, methyl ?i-amyl ether, and ethylenechlorohydrin all show three series of band spectra, identical with those previously found in benzene. As the only linkings common to the compounds compared are the carbon-hydrogen and carbon-carbon linkings, it appears that one or other of these gives riso to the band systems. On this assumption, the positions of the absorption bands in the near infra-red are found to agree with those calculated from the positions of the observed ultra­

violet bands by Henri’s formula based on the quantum

theory (A., 1922, ii, 679), and it is shown that these positions agree with those reported for a large number of organic liquids. F. G. Wi l l s o n.

Absorption spectra and the constitution of benzene derivatives. IX. N. A. Va l a s c h k o (J.

Russ. Phys. Chem. Soc., 192G, 58, 779— 822).— See this vol., 396. E . Ro t h s t e i n.

Ultra-violet absorption spectra of substances containing two benzene rings. A. C a s t i l l e

(Bull. Soc. chim. Belg., 1927, 36, 292— 309).— The absorption spectra of a series of compounds containing two benzene rings have been studied, in hexane solution and in the vapour state, over the range 4000— 2000 A. The coefficients of absorption are considerably greater than the corresponding values for compounds containing a single benzene ring.

The spectra of diphenylmethane and of dibenzyl show the seven narrow bands characteristic of benzene, which are, however, broader and displaced towards the visible region by about 90 A. Com­

pounds in which the two rings are joined by an unsaturated chain exhibit a single wide band resulting from the fusion of the narrow benzene bands, with, in some cases, a second band corresponding with the benzene band in the extreme ultra-violet. An increase in the length of the connecting chain is accompanied by a displacement of these bands towards the region of longer wave-lengths. The coefficients of absorption increase with the number of ethylenic linkings; diphenylamine, however, possesses an abnormally high power of absorption.

When the two benzene rings are linked by a group containing a chromophore, as in benzil or azobenzene, the modified benzene bands are displaced, and one or more bands characteristic of the chromophore appear near the visible region. G. A. E l l i o t t .

Resonance, fluorescence, and absorption spec­

tra in group VI of the periodic system. B. R o s e n

(Z. Physik, 1927, 43, 69— 130).— The resonance spectra of tellurium, selenium, and sulphur vapours are very similar to the resonance spectra of iodine in respect of fine structure and intensity relations. The resonance spectra of tellurium are given by v = a — 250-4?i-f0'53n2, where a has the values 23,930, 25,451, and 22,411, respectively, for the exciting mercury lines 4359, 4046, and 5461 A. For selenium, the analogous expression is v—a— 397-5rc-l-l-32tt2, a being 27,423 for the 4046 series, whilst for sulphur v = a —724-ora—2-91ra2, a being 33,359 for 3132 A The vapour fluorescence in this group begins to be marked at pressures of the order 10~3 mm., and in­

creases up to pressures of 1 mm., beyond which point surface fluorescence occurs. The disappearance of the fluorescence is due largely to re-absorption.

With tellurium, the effect of foreign gases is limited to a weakening of the intensity. The absorption and fluorescence spectra of all three elements have been analysed and classified schematically, and formulse derived. It is shown that the higher the level to which a molecule is raised by the absorption o f the exciting line the more numerous will be the

“ anti-Stokes ” lines. The nudlear vibration fre­

quencies in the normal state are approximately inversely proportional to the atomic numbers, a

GENERAL, PHYSICAL, AND INORGANIC CHEMISTRY. 609

conclusion valid for groups V, VI, and V II of the periodic system. It follows, therefore, that the binding force is approximately inversely proportional to the atomic numbers or to the atomic weights.

The heats of dissociation of diatomic sulphur, selenium, and tellurium are found by the optical method to be 112,000±5000,84,000, and 65,000 g.-eal., respectively. R. A. Mo r t o n.

Fluorescence and molecular induction by resonance. J. Pe r r i n (Compt. rend., 1927, 184, 1097— 1100).— Activation occurs when a molecule changes suddenly to a state of higher internal energy as the result of the absorption of a quantum from an exciting source. Fluorescence, which may thus be correlated with deactivation, the reverse of activ­

ation, is shown to increase as the concentration of the solution diminishes, since at high concentrations the molecules are closer together and the proportion of non-luminous deactivations is increased. Molecular induction is the non-luminous deactivation, with the expulsion of kinetic energy, resulting from the proximity of an ordinary and an active molecule of the same substance. Selective molecular induction by resonance may he produced between molecules of different substances the absorption bands of which are close or identical. Thus eosin lowers the fluorescence of uranium more than uranium itself.

When the absorption bands of the fluorescent sub­

stance and the added substance are dissimilar, the mutual induction is less pronounced. The coefficient of mutual induction may be calculated analogously to the method for F. Perrin’s expression for the exponential decrease of fluorescence (cf. following

abstracts). J. Gr a n t.

Action of anti-oxygenic compounds on fluores­

cence. Pr i v a u l t (Compt. rend., 1927, 184, 1120—

1121; cf. preceding and following abstracts).— The reducing effect of certain anti-oxygenic salts (e.g., iodides, sulphides, etc.) on the luminosity of fluorescence (A., 1926, 223) is due to the physical actions of the ions concerned on the excited molecules of the fluorescent substance, which favour a return to the normal state without emission of light. Such substances should also lower the photochemical activity of fluorescent substances. Thus, quinol inhibits the photochemical oxidation of uranium and also its power of fluorescence, and the latter action has the same physical characteristics as those referred to above. Other anti-oxygenic compounds (phenols, nuclear amines, certain sulphur and nitrogen compounds, and, to a lesser extent, the aliphatic amines and pyridine) behave similarly. The phenomenon is

non-chemical. J. Gr a n t.

Induced deactivation of molecules and the theory of anti-oxygenic compounds. F. P e r r i n

(Compt. rend., 1927, 184, 1121— 1124).— The pheno­

menon observed by Privault (cf. preceding abstract) is styled forced induction (in opposition to resonance induction), and is related to the deactivation of an excited molecule by a free electron such as would be ound loosely bound in an easily oxidisable substance ike an anti-oxygen. An explanation of anti-oxygenic ettects is to be found in a chain theory of reaction (.such as Bodenstein’s), in which the energy liberated

by a reacting molecule supplies energy to activate other molecules, which can then also react. The diminution of the mean lives of the activated molecules by the deactivating molecules diminishes the chances of reaction of the former. Thus, anti­

oxygens may also inhibit certain photochemical reactions which are not necessarily oxidations.

J. Gr a n t.

Luminescence of cæsium vapour in the silent discharge. G . Ba l a s s e and O. Go c h e (Bull.

Acad. roy. Belg., 1926, [v], 12, 835— 839).— A pre­

liminar}' investigation of the cæsium spectrum pro­

duced in the silent discharge shows that all the lines of the arc spectrum are present, together with some of the spark lines. Several faint diffuse lines in the arc series 1 s —md, which have not been observed previously, have been measured. There is some continuous spectrum produced at temperatures above about 200°. The spectra obtained with decreasing intensity of excitation extend less and less into the short wave-length region, an effect which is thought to be independent of the substance studied. The differentiation among rays of the spark spectrum, observed with certain intensities of excitation, is not thought to be due to ionisation with the loss of one and two electrons, as required by Bohr’s theory of the structure of the cæsium atom. H. F. Gi l l b e.

Excitation of phosphorescence by means of slow cathode rays. H. W . Er n s t (Ann. Physik, 1927, [iv], 82, 1051— 1076).— With the CaS-Cu phosphor the a- and [3-bancLs are excited both by cathode rays and light, but the a-band is much the stronger of the two with light, whereas the (3-band predominates slightly with cathode-ray excitation.

The specific light intensity during cathode-ray excitation is over a wide range directly proportional to the electron density, if the voltage is maintained

• constant. An upper limit to the degree of excitation was not reached. The economy quotient for a defined CaS-Bi phosphor was 0-11, and for other phosphors it was even smaller. Curves expressing the relation between specific light intensity and electron-accelerating potentials are given. For small velocities, the rate of increase of intensity is slow, but as the velocity increases, the intensity gradually approaches a linear rate of increase, which is main­

tained until the velocity becomes large. For the same band occurring in different preparations with different intensities and voltages (so long as these are not too great), the same economy quotient is obtained, provided the metal content is maintained constant. The momentary light exerts no appreciable effect. The economy quotient for CaS-Cua and CaS-Cu(3 increases with increasing metal content up to a maximum of 0-13 and 0-10 at 0-75 x lO '3 and 0-9 X 10~3 g. of copper per g., respectively ; it falls off somewhat rapidly with further increase of con­

centration. R . A. Mo r t o n.

Dielectric constants and magnetic suscepti­

bilities in the new quantum mechanics. I.

General proof of the Langevin-Debye formula.

J. H. V a n V l e c k (Physical Rev., 1927, [ii], 29, 727— 744).— Mathematical. The proof of the formula X = N a.-\-N$/Z1cT, where x '-s the susceptibility,