BRITISH CHEMICAL ABSTRACTS
A .- P U R E CHEMISTRY
___________________
JULY, 1928.
G en eral, P h y sic a l, and In o rg a n ic C h em istry .
P r i m a r y d a r k s p a c e of a G e is s le r d is c h a r g e . K . B. Em e l e u s and (Mi s s) N. M . Ca r m ic h a e l (Phil.
Mag., 192S, [vii], 5, 1039— 1048).—Some of th e properties of th e p rim ary d ark space on th e cold cathode of a Geissler discharge can he accounted for b y an application of th e equations developed by Langm uir for th e positive ion sheaths present on exploring cathodes. There are, however, discrep
ancies which indicate th a t the cathode receives fast electrons from ad jacent p a rts of th e discharge which could subsequently produce a secondary electronic emission from the m etal. A. E . Mi t c h e l l.
E m is s io n of p a r ti c le s f r o m h o t p la t in u m in a i r a t a tm o s p h e r ic p r e s s u r e , W . D. Fl o w e r
(Phil. Mag., 1928, [vii], 5, 1084— 1094).—The W ilson cloud m ethod has been emplojred for th e ultra- microscopic exam ination of th e large ions an d nuclei em itted from a h o t platin u m wire in air a t norm al pressure. A fter removing th e source of th e nuclei it was found th a t th e num ber visible increased to a m axim um an d th en dim inished, a result which is explained on th e th eory th a t a t emission the nuclei are too sm all to be seen an d subsequently coagulate.
The coagulation of th e nuclei has been observed and th e ra te of coagulation is expressed by th e equation d n /d t— — kn2, where n is th e num ber of particles present an d k is a c o n sta n t= 0-15 X 10~8 cm.3/sec.
This value is in fair agreem ent w ith th e value 0-13 X
1 0 "8 cm .3/sec., obtained by K ennedy for large ions and nuclei from a B unsen flame. A. E . Mi t c h e l l.
F in e s t r u c t u r e of t h e s p e c tr u m lin e s of t h a lliu m in th e u ltr a - v io le t. W. Mo h a m m a d and S. B. L. Ma t h u r (Phil. Mag., 1928, [vii], 5, l l l l - l l 14).—Of th e tw enty-one lines of thallium reported by E x n er an d H aschek betw een 6550-15 an d 25S0-25 A., only eleven have sufficient intensity to be ph o to graphed by th e aid of a q u artz Lum m er-Gehrcke plate. The fine stru ctu re of these lines has been exam ined an d the positions of the satellites are given.
A. E . Mi t c h e l l. D is tr ib u tio n of e le c tro n s a m o n g a to m ic lev els.
E. C. St o n e r (Proc. Leeds P hil. Soc., 1928, 1, 226—
231).—Theoretical. I t is shown th a t electrons m ay be divided into n, k groups, b u t a subdivision into n, k, j grouplets is n o t justifiable. F or an n, k group for which th e m axim um num ber of electrons is z [z =2(2&— 1)] the X -ray sub-level scheme is appro
p riate when th e group contains 1 or z— 1 electrons.
F or other num bers of electrons, the level scheme is com pletely different, corresponding w ith other m ultiplicities. W. E. Do w n e y.
x x 677
S p e c t r u m of io n is e d s o d iu m . K . Ma j u m d a r
(Indian J . Physics, 1928, 2, 345—354).—The spectral lines of sodium h av e been classified by th e application of th e irregular doublet law. A n approxim ate value of 47 volts is deduced for th e ionisation p o ten tial of
sodium. M . S. Bu r r.
E x te n s io n of th e i r r e g u l a r d o u b le t la w to c o m p le x s p e c tr a . M. Sa h a and P . K . Ki c h l u (Indian J . Physics, 192S, 2, 319—342).—The d a ta for Milli- k an an d Bowen’s irregular d oublet law have been collected and tab u lated , an d th e law has been shown to hold good in th e case of complex spectra. On th e basis of th is law the ionisation p o ten tial of carbon should be approxim ately 11 volts. This has been confirmed experim entally (Fowler, N ature, 1928,121, 304). Predictions have also been m ade w ith regard to spectral lines which are still unknow n, belonging to o th er elem ents. M. S. Bu r r.
R e g u la r itie s in th e s p e c tr a of s e x a v a le n t e le m e n ts . D . S. Jo g (Indian J . Physics, 1928, 2, 343—344).—The stru ctu re of spectra m ay be eluci
d a te d by com paring th e spectra of successive ele
m ents which, b y electric discharge, have been reduced to th e same electronic configuration, e.g., O, F +, and N a ++. Several lines have been identified as belonging to these elem ents by th e help of th e extension of th e irregular doublet law discussed by Saha an d K ichlu (cf. preceding ab stract). M. S. Bu r r.
S c a t t e r in g of e le c tro n s b y c r y s ta ls . H . Be t h e
(Naturwiss., 1927,15. 786—788; Chem. Zentr., 1928, i, 154).
E x c ita tio n fu n c tio n of s p e c tr a l lin e s . W.
H a n l e (Naturwiss., 1927, 15, 832—833; Chem.
Z entr., 1928, i, 158).—T he excitation function (excitation probability in relation to the acceleration voltage of th e bom barding electrons) of th e m ercury line 2537 A. has been observed in th e neighbourhood of th e excitation potential. A. A. E l o r i d g e .
N e w ty p e of d is c h a r g e in n e o n tu b e s . J . W.
Ry d e, L. Ja c o b, an d B. S. Go s s l i n g (Nature, 1928, 121, 794).
R y d b e r g t e r m ta b le s . F . Pa s c h e n (J. Opt.
Soc. Amer., 1928, 16, 231—24 3 )— Values of Z 2N / ( r a + a)2 are tab u lated for Z==d , 2, 3, an d 4, Z being th e num ber of th e spectrum , N R ydberg’s constant, m th e order num ber of th e term , and a th e R ydberg
correction. C. W. Gi b b y.
N e w r e g u la r i t ie s in th e b a n d s p e c tr u m of h e liu m . G . H . Di e k e, T . Ta k a m i n e, and T . Su g a
(N ature, 1928, 121, 793—794).—More th a n 20 new
678 BRITISH CHEMICAL ABSTRACTS.--- A.
bands, and p arts of other bands, have been found;
m ost of the new bands have the 2p state as final state.
Besides bands in which term s of a new' ty p e are involved, there were found new bands originating from th e com bination of C urtis’ term s w ith th e vibrational quantum num ber 1 an d 2.
A. A. El d r i d g e. /f - E le c tr o n io n is a tio n b y d ir e c t im p a c t of c a th o d e r a y s . D. L. We b s t e r (Proc. N at. Acad.
S c i, 1928, 14, 339—344).-—The assum ptions un der
lying the theory of indirect /¿"-ionisation used in previous work (this vol., 691) and here, are first tested by finding th e ratio of th e indirect /ix-line rays of silver to its continuous spectrum rays of th e same wave-length. This should be independent of all questions of resolving power, sensitivity function, etc. The results obtained are of the right order, although no t strictly accurate. The probability of direct ii-ionisation by a cathode ray in silver is found to be 0-9 times the probability of an equivalent quantum emission in the continuous sp e c tru m ; th e ratio is practically constant w ith change of voltage, an d therefore m ust hold, n o t only for ordinary th ick targets, b u t for infinitely th in targ ets also. The absolute probability of direct /¿'-ionisation is also estim ated w ith large lim its of error, an d found to agree w ith Thom as’ theory. I t seems probable th a t the process of direct ionisation is n o t usually an intern al photo-electric effect, b u t ra th e r a process of repulsion between electrons obeying laws m uch like the inverse square law. A. J . Me e.
A n a ly s is of s p e c tr a a r is in g f r o m q u a d r u p ly - io n is e d tin , S n v . R. C. Gi b b s and H . E. Wh i t e
(Proc. N at. Acad. S c i, 1928, 14, 345—348).—Most of the strong lines in th e spectrum of S n v have been identified. A table showing th e intensities, wave
lengths, an d frequencies of th e identified lines is given, and th e spectrum is analysed. A. J . Me e.
S tr u c t u r e of s o m e s p e c tr a w it h r e g a r d to r e c e n t th e o r e tic a l c o n s id e r a tio n s . T. L. d e
Br u i n (Arch. N é erlan d , 1928, [iii], A, 11, 70— 153).—
A comprehensive paper giving th e results of researches which confirm th e spectroscopic displacem ent law of Sommerfeld and Kossel. The arc and spark spectra of several elements were photographed, using th e m ethod of discharge w ithout electrodes. The spectrum of potassium was exam ined an d th e exist
ence of two characteristic spectra shown. One is yellowish-green and the other is bluish-violet. The form er is due to th e n eu tral atom , K I, th e la tte r to th e singly-ionised atom , K n , and is com paratively simple. The spectrum of K ii was analysed and com pared w ith th a t of n eutral neon, Ne i, and neutral argon, A i. I t shows some analogy to both these spectra, as it should do if the Bohr theory is correct.
The stru ctu re of the spectrum is discussed in relation
ship to th e configuration of the atom . I t is also shown th a t th e 3;t stru ctu re is m ore stable th a n th e 42, which is n o t so for th e rare gases. The Zeeman effect in th e case of th e K i i lines was examined p artly for ordering the spectrum , an d p artly in an a tte m p t to verify th e theory of Landé an d Heisen
berg, b u t th e diffuse w ay in which th e lines split m ade m easurem ents impossible. The spectra of
doubly-ionised potassium , K in , and triply-ionised potassium , K iv, were difficult to study, b u t should be equivalent to those of non-ionised fluorine, F i, and chlorine, Cl I, an d singly-ionised fluorine, F n , and chlorine, C ln , respectively. The spectrum of fluorine was obtained by passing a discharge w ithout electrodes through silicon tetrafluoride. The theo
retical scheme for term s of F i is draw n up, and th e term s found are experim entally identified. The ionisation p o tential of fluorine calculated from the fundam ental term is found to be 16-7 volts. The spectrum of singly-ionised fluorine F n was inves
tigated an d com pared w ith th e analogous spectra of non-ionised oxygen, 0 1, and non-ionised sulphur, S i ; th e stru ctu re is shown to be similar. The spectrum of singly-ionised neon, Ne n , wras analysed and shown to be analogous to th a t of non-ionised fluorine, w hilst th a t of doubly-ionised neon, N e in , is sim ilar to th a t of singly-ionised fluorine. The structure of th e term s of th e spectra exam ined con
forms to the new th eory of Heisenberg and H und on complex spectra. The spectra of selenium, arsenic, and indium were investigated by th e same m ethod w ith a view to relate them w ith th e theory
of H und. A. J . Me e.
S p e c tr u m of io n is e d n e o n . T. L. d e Br u i n
(Proc. K . Akad. W etensch. A m sterdam , 1928, 31, 2— 13).— 180 Lines of the spectrum of ionised neon (Ne i i) have been classified in a term scheme and th e deepest quadruplet term s identified. The N e ii spectrum has a stru ctu re analogous to th a t of the F I spectrum . This is in agreem ent w ith the theory according to which th e spectra of the ionised rare gases should have th e same stru ctu re as th e F I spectrum (cf. A , 1927, 82). I n Ne n th e term s have approxim ately double th e value of the analogous
term s of F I. M. S. Bu r r.
I n te n s ity m e a s u r e m e n t s in th e s e c o n d a ry s p e c tr u m of h y d ro g e n . L. S. Or n s t e i n, W.
Ka p u s c i n s k i, an d (Miss) J . G. Ey m e r s (Proc. Roy.
S o c, 1928, A, 119, 83—91).—The figures given by M cLennan for th e intensities in th e secondary spec
tru m of hydrogen (A , 1927, 1004) are only densities, and it is shown th a t, since th e relations between density an d intensity are n o t simple, M cLennan’s values could n o t be used for theoretical investigations of th e secondary spectrum . The intensities of about 230 lines over th e region 4500—4900 A. have now been m easured by the U tre ch t m ethod. In this region, th e value of th e sensitivity of th e photo
graphic p late depends strongly on th e wave-length, and allowance was m ade for this. The m ethod used for the analysis of closely ad jacen t lines is described in detail. The inten sity values are com pared w ith M cLennan’s d en sities; for m oderate intensities the ra tio of th e results is alm ost constant, b u t no propor
tio n ality is shown for higher intensities.
L. L. Bir c u m s h a w. R e la tio n b e tw e e n m e a n s to p p in g p o w e r a n d m e a n r a n g e of (3-rays. . E . J . Wi l l ia m s (Proc.
Camb. Phil. S o c, 1928, 24, 315—319).—The tru e ra te of loss of energy or “ stopping power ” of [3-rays is th e q u an tity d T /d x, w'here d T is th e m ean energy lost by rays of energy T in travelling a distance dx
GENERAL, PHYSICAL, AND INORGANIC CHEMISTRY. 6 7 9
along th eir paths. The cloud m ethod enables only the to ta l ranges of (3-particles to be observed, and in deducing th e stopping power from th e m ean range R , d T /d R is n o t exactly th e same as d T /d x, owing to straggling. The relation betw een these two q u an tities is calculated so th a t th e cloud m ethod m ay be rigorously interpreted. F or rays of 10,000 volts traversing light elem ents the correction is ab o u t 7% , whilst for a-rays it is negligible. C. J . Sm i t h e l l s.
A b s o lu te in te n s ity m e a s u r e m e n t s o n th e s o d iu m fla m e . D u r a tio n of th e e x c ite d s ta te . L . S. Or n s t e i n and E. F . M. v a n d e r He l d (Ann.
Physik, 1928, [iv], 85, 953—960).—The absolute intensity of th e green m ercury line from a quartz lamp was first m easured an d th en photographic com
parisons were m ade of the sodium flame and the yellow light from a N itra lam p, and th e green line w ith the green light from th e N itra lam p. F or the sodium flame, 250 q u an ta per sec. per atom are em itted a t 1970° Abs. The E instein equation leads to the value 5 x l 0~8 sec. for the period of excitation as .against th e values 1-6 an d 3-8 x l 0~8 sec. due to Minkowski (A., 1926, 650) an d K erschbaum (A., 1926, 652), respectively. R . A. Mo r t o n.
M e th o d s of e s t im a t in g th e i n te n s itie s of s p e c tr a l lin e s . W. H . J . Ch i l d s (Proc. Physical Soc., 1928, 40, 132— 148).—A critical discussion of several m ethods of spectral p h otom etry applied to the special case of th e b and spectrum of helium is given. The. preferred m ethod is to photograph the line spectrum in th e usual w ay an d th en calibrate the p late by illum inating th e slit w ith a tungsten- filam ent lam p in such a w ay th a t on developm ent a num ber of continuous spectra of progressively increas
ing density are obtained. From these images the relation between the intensity of light and density of image, and between p late sensitivity and w ave
length, m ay be ascertained. D ensity m easurem ents are obtained by m eans of a selenium cell m icro- photom eter. C. J . Sm i t h e l l s.
S t r u c t u r e of th e s e c o n d o r d e r s p e c tr u m of s u lp h u r. J . Gi l l e s (Compt. rend., 1928, 186, 1354— 1355).—The values of th e com binations of the m ultiplets a m j^ S andiP of th e S n spectrum , are deduced from those previously published (cf. this
vol., 565). J . Gr a n t.
C e rta in m u ltip l e t s in th e s p e c tr a of C d i n a n d In iv . R. C. Gi b b s and H . E . Wh i t e (Physical Rev., 1928, [ii], 31, 776—781).—W ith th e aid of th e tra n sitions from 3PJ)F, 1P I)F (4d95p) to 3D, lD(4d'Jos) already determ ined for P d I and Ag II, th e corre
sponding lines in th e spectra of Cd h i and I n iv have been identified an d ta b u la te d ; th e transitions from 3D V 3P 1, an d 1P1(4d95jj) to 1<S'0(4fZ10), th e lowest level, have also been identified for Ag n , Cd h i, and In iv. The validity of th e irregular doublet law is confirmed. " A. A. El d r i d g e.
A p p lic a tio n of th e X -ra y la w s to o p tic a l s p e c tr a of h ig h e r r a n k , a n d th e c la s s ific a tio n of G a i v a n d Ge v . J . E . Ma c k, 0 . La p o r t e, and R. J . La n g (Physical R ev., 1928, [ii], 31, 74S—772).—The (3c£94s) and (3d94p) levels of Ga iv an d Ge v, and a te n ta tiv e (3d10) level for Ga iv have been found, and
th e levels form erly classified as 3D V 1P1(3rf°4p) of Zn h i have been interchanged. Evidence is adduced to show th a t of the 3D, W ^P s) th e 3D 2 level approaches th e lim it 2£>3(d9), co ntrary to H u n d ’s theory. Dis
tinctions between X -ray an d optical spectra in application of th e X -ray laws are considered, as also is th e shape of th e c 1 (first order screening num ber) curve for isoelectronic spectra. The irregular doublet law is n o t always valid. A. A. El d r i d g e. A rc s p e c tr u m of g e r m a n iu m . C. W . G a r t l e i n (Physical R ev., 1928, [ii], 31, 782—792).—The w ave
lengths (± 0-03 A.) of germ anium arc lines above 1870 A. are ta b u la te d ; the relative energy levels have been determ ined an d transitions corresponding w ith 73 lines identified. The first resonance potential is 4-65 volts and th e ionisation p otential determ ined by th e lim it 2P 1 is 7-85 volts. Sim ilarities in the arc spectra of silicon, germ anium , tin , and lead are
considered. A. A. E l d r i d g e .
L o w e s t t e r m s in th e s p a r k s p e c tr u m of n ic k e l a n d c o p p e r (N i n a n d C u i i). R . J . La n g (Physical R ev., 1928, [ii], 31, 773—775).—In th e spark spec
tru m of nickel th e lowest term s 2D23(d°) lie 6884 and 8391 cm.-1 below (PF\ ; in th a t of copper 1S 0(d10) lies 21925 cm.-1 below a3Z>3. A. A. El d r i d g e. A rc a n d s p a r k s p e c tr a of t i ta n iu m . I. S p a r k s p e c tr u m , T i II. II . A rc s p e c tr u m , T i I.
H. N. Ru s s e l l (Astrophys. J ., 1927, 6 6, 283—328, 347— 43S).—I. All b u t th e w eakest lines have been classified; 33 doublet an d 17 quadru plet term s have been identified. Three series of two m em bers each indicate an ionisation p o ten tial of 13-6 volts. H u n d ’s th eo ry of th e relation of spectral lijies to electronic configurations in the atom is confirmed. A com parison of th e spectra of Ti n and Sc i shows th a t Moseley’s law is closely satisfied.
II . The arc spectrum is com plicated; 43 singlet, 65 trip let, and 34 q uintu plet term s have been id en ti
fied. There are no intercom binations betw een sing
lets and quintuplets. H u n d ’s theory is again con
firmed. Seventeen series, converging to seven differ
en t lim its, all term s of Ti n , have been iden tified ; th e ionisation p o ten tial is 6-81 volts. The spectra of Ti i an d V ii are sim ilar in s tru c tu re ; com parison indicates th a t the ionisation p o ten tial of V n is approxim ately 14-1 volts. A. A. El d r i d g e.
Z e e m a n e ffec t a n d s p e c tr a l t e r m s in th e a r c s p e c tr u m of p la tin u m . A. C. Ha u s s m a n n
(Astrophys. J ., 1927, 6 6. 333—346).—The Zeeman effect of 173 arc lines of p latin um was investigated in th e region 5500—2500 A . ; 33 of th e lines could be identified from their p attern s. Twelve low levels have been identified; th e ground term is 3D3, d9s.
There are 45 interm ediate and 15 high levels. P ra c tically all th e strong lines in the arc spectrum are a ttrib u te d to com binations between these levels.
A. A. El d r i d g e. W a v e -le n g th s of c a rb o n , o x y g en , a n d n itr o g e n i n th e e x tr e m e u ltr a - v io le t w ith a co n c av e g r a t i n g a t g r a z in g in c id e n c e . J . B. H o a g (Astrophys. J ., 1927, 6 6, 225—232).—W ith a vacuum spectrograph of special design, wave-lengths from 1658 to 558 A. for spark discharge through mag-
68 0 BRITISH CHEMICAL ABSTRACTS.— A.
nesiurn and carbon electrodes were o b tain ed ; by passing gases through th e electrodes, gaseous an d metallic spectra are sim ultaneously obtained.
A. A. El d r i d g e. S e c o n d a ry s t a n d a r d s of w a v e -le n g th ; i n t e r f e r o m e te r m e a s u r e m e n ts of ir o n a n d n e o n lin e s . H . D. Ba b c o c k (Astrophys. J ., 1927, 6 6, 256—282);
—S tan d ard wave-lengths are recorded for 286 iron lines, X 3407—6677 A., an d for 11 neon lines, >. 5852—
6506 A'., m easured in term s of th e p rim ary standard, 6438-4696 A., of cadm ium . The neon wave-lengths agree precisely w ith th e values adopted as secondary standards, b u t th e n o n wave-lengths are system atic
ally smaller th a n the adopted values. The differences are discussed. A. A. El d r i d g e.
A b s o r p tio n s p e c tr u m of m e r c u r y a t h ig h p r e s s u r e a d m ix e d w ith n itr o g e n . H . R . M o o r e (Science, 1927 , 6 6, 543—544).—The bands already observed (Mohler an d Moore, A., 1927, 917) have been extended tow ards the red to 3087 A. a t 215—- 305°, an d tow ards the violet to 2666 A. a t 425—530°, b y th e addition of nitrogen. F orty-tw o such bands were observed. The b an d a t 2528 A. was always obtained w ith m ixtures of m ercury an d nitrogen, an d appears to be definitely conditioned by th e presence of nitrogen. Resonance broadening increases w ith th e pressure of th e nitrogen. The extension of th e bands m ay be ascribed to th e increase in concentration of H g2 molecules resulting from th e com bined effect of th e nitrogen an d th e rad iatio n used as a source, or th ey m ay represent th e v ibrational spectra of H gN , molecules, unstable or quasi-stable, form ed betw een nitrogen molecules an d excited m ercury atom s.
A . A . El d r i d g e. B a n d s p e c tr u m of m e r c u r y e x c ite d b y a h ig h - fre q u e n c y d is c h a r g e . J . G. Wi n a n s (N ature, 1928,121, 863—864).—The spectrum of th e discharge showed the m ercury arc lines an d the m ercury bands w ith m axim a a t 4850, 3300, 2540, an d 2345 A. ; distilling vapour is necessar3r for the ex citatio n of the bands 4850, 3300, an d 2345 in a high-frequency discharge. The ban d a t 4850 A. is destroyed b y local heating. The initial excited sta te for th e ban d 4850 A. differs from th a t of th e b an d a t 3300 A. an d from those of the bands a t 2345 and 2540 A., b u t th e final states of th e bands a t 2345 and 2540 A. are th e
same. A. A. El d r i d g e.
S p e c tr a of d o u b ly - a n d tre b ly -io n is e d t ita n iu m . (T i h i a n d T i iv ). H . N. R u s s e l l an d R. J . La n g
(Astrophys. J ., 1927 , 6 6, 13—42).—T hirty-one new lines of Ti iv and 90 lines (mostly new) of T i i n have been identified between 5492 and 423 A . ; all th e form er an d all b u t four of the la tte r have been classified.
Twelve term s are tab u lated for T i i v ; th e 3D term is th e lowest, an d th e ionisation p o ten tial is 43-06 volts. N ineteen term s were identified for Ti i l l ; th e estim ated ionisation p otential is 27-64; 1-0 volts.
The spectrum of Sc m is briefly discussed.
Ch e m i c a l Ab s t r a c t s. P h o to g r a p h y of th e in f r a - r e d s o la r s p e c tr u m . H . D. Ba b c o c k (N ature, 1928, 121, 830—831).—
A bout 1 2 lines betw een 1 0 0 0 0 an d 10750 A. have been observed on prism atic plates, one a t 10049-8 A.
being specially conspicuous; it is evidently th e fourth
m em ber of th e Paschen series of hydrogen. On grating plates a num ber of lines were also observed.
A. A. El d r i d g e. A p p lic a tio n of th e i r r e g u l a r d o u b le t la w to c o m p le x s p e c tr a . K . Ma j u m d a r an d G. R.
To s h n iw a l (N ature, 1928, 121, 828—829).—Saha a n d K ichlu’s application of the irregular doublet law to complex spectra (this vol., 209) is confirmed in the groups Ne, N a +, Mg+ + and A, K +, Ca+ + . The: view th a t th e spectrum of th e solar corona is composed of th e lines of Ca+H_ is n o t supported. The ionisation p o ten tial of Ca~^ is about 52 volts.
A. A. El d r i d g e. R e la te d lin e s in th e s p e c tr a of th e e le m e n ts of th e i r o n g ro u p . H . N. Ru s s e l l (Astrophys. J ., 1927, 6 6, 184—216).—T h e arc and spark spectra of potassium , calcium, scandium , titan iu m , vanadium , chromium, iron, cobalt, nickel, copper* and zinc have been classified sufficiently to illu strate th e sim ilarity of spectral groups resulting from sim ilar electron transitions. Homologous term s an d homologous lines as n varies from 1 to 1 2 are tabu lated.
Ch e m i c a l Ab s t r a c t s. S p e c t r u m of io n is e d s o d iu m . 0 . La p o r t e
(N ature, 1928, 121, 941).—B y using one of th e differences between p a h s of lines in th e N a i ispectrum (Newman, 1 his vol., 210), it is possible to arrange num erous strong lines as com binations of four s term s w ith te n j) term s corresponding w ith th e transition 3s1 3P —3?:)1 2 (S,P,D ). A. A. El d r i d g e.
O p tic a l c h a r a c te r is a tio n of s p a r k e m is s io n s p e c tr a . G. I . P o k r o w s k i (Z. Physik, 1 9 2 8 , 4 8 , 5 8 6—5 9 3 ).—B y assum ing th a t th e energy consum ed in a spark is proportional to th e square of th e root m ean square value of th e curren t flowing throug h the arc, th e to ta l in ten sity I of n spectral lines is shown to be related to th e curren t i and to th e absorptive power, k, of th e m etal vapour through which th e sp ark takes places b y th e expression I= a i--\-b ( 1 — erkci'), where a, b, an d c are constants. I t is also shown th a t for a given value of i, I is linearly related to th e width, of th e sp ark gap. D a ta relating to lines 5 0 0 0 , 5 2 0 0 , 5 8 9 0 A. in th e spark betw een copper an d electrodes are shown to be in agreem ent w ith th e
above expression. R . W. L u n t .
A c tiv e n itr o g e n . P . K . K i c h l u and D. P . A c i i a r y a (N ature, 1928, 121, 982—983).—The spec
tru m of active nitrogen includes a b and system from 7500 to S900 A., doubtless originating from the N2 molecule, an d presum ably analogous to A , B , a bands of oxygen. The results of McLennan, R uedy, and Anderson (this vol., 456) are criticised.
A. A. El d r i d g e. N e w p h o to -e le c tric p h e n o m e n o n w i t h t h i n s h e e ts of a lk a li m e ta ls . R . Su h r m a n n (N atur- wiss., 1928, 16, 336).—W hen th in sheets of alkali m etals are illum inated w ith th e m ercury 240 [4/. line, th e lig ht intensity -vo ltag e characteristic reaches a sharp satu ra tio n value a t a few volts. A t th e red lim it (313 ¡xa), however, it rises steadily w ith increasing p otential. The sam e phenom enon is found b u t to a less degree w ith thicker sheets. J . W . Sm i t h.
P r e d ic te d io n is a tio n p o te n tia l of r a d o n . S. C.
Bisw as (Phil. Mag., 1928, [vii], 5, 1094—1098).—I t
GENERAL, PHYSICAL, AND INORGANIC CHEMISTRY. 6 81
is shown th a t th e ionisation p o ten tial of an atoin is given b y th e expression / (V0ll6)= 3-S 3/m /r2, where k and n are respectively th e azim uthal an d radial q u antum num bers of th e external electron and r2 is the m ean square radius of th e nk orbit. Since for elements of th e sam e group of th e periodic classi
fication k is constant, i t follows th a t th e ionisation potentials of these elem ents will be proportional inversely to th e square of th e radius an d directly to the rad ial q u antum num ber. From crystal stru ctu re and other m easurem ents it is shown th a t th e atom ic radius of rad o n shonld be 1-81 ¿ 0 -0 3 A., whence taking the q u antum num bers in question as 6 an d 2 th e ionisation p o ten tial should be 14-0 ± 0 -5 volts, a result in general accordance w ith th e know n values for k ry p to n arid xenon, b u t in disagreem ent w ith th e predictions of T urner (A., 1924. ii, 797) and others.
A. E . Mi t c h e l l. C a u se of lo s s of t h e r m io n ic a c tiv ity of th o r i a t e d tu n g s te n f ila m e n ts u n d e r c e r ta i n v o lta g e c o n d itio n s . (Miss) A. C. Da v i e s a n d (Miss) R . N.
Moss (Phil. Mag., 1928, [vii], 5, 989— 1010).—I t is found th a t loss of therm ionic ac tiv ity is due to th e bom bardm ent of th e filam ent by positive ions which originate in th eir tu rn from th e electron bom bard
m ent of th e grid and plate. W. E. Do w n e y. E le c tr o n th e o r y of m e ta ls . A. So m m e r f e l d
(Naturwiss,, 1927, 15, 825—832; 1928, 16, 374—
381 j,—The old electron theory of m etals is discredited, b u t i t can be reh abilitated w ithout th e adoption of new physical assum ptions. The statistical tre a tm e n t of the assum ptions of D rude and Lorentz m u st be replaced by a new tre a tm e n t based on th e wave- mechanics. The present work is concerned m ainly w ith th e developm ent of a wave-m echanical th eory of conductivity in m etals, and the variations w ith changes in tem p eratu re and pressure. S tartin g from the P auli principle and th e F erm i-D irac statistics, it is shown th a t th e m ean velocity of an electron-gas is independent of te m p eratu re; wave-lengths in term s of de Broglie’s ideas are th en calculated, and after considering th e R ichardson and V olta effects, i t is possible to develop th e theory of m etallic conduction so as to obtain satisfactory agreem ent betw een the observed and calculated d ata. A final section is devoted to th e direction-dependence of conductivity and th e th erm al forces in unicrystalline m aterial.
R . A. Mo r t o n. E le c tr o n e m is s io n in in te n s e e le c tric field s.
R. H . Fo w l e r an d L. No r d h e i m (Proc. R oy. Soc., 1928, A, 1 1 9 ,173—1 8 1) .—The phenom enon of electron emission in intense fields can be accounted for in a satisfactory q u a n tita tiv e w ay by Somm erfeld’s revived electron th eo ry of m etals (see preceding abstract). N ordheim ’s results (this vol., 4 5 2 ) are extended to include th e effect of an external field, using th e sam e m ethods and th e same underlying picture of th e m etal. The form ula 1 = CF2e~al1' is established, independent of th e tem perature a t low tem peratures, in agreem ent w ith experim ent. No theoretical justification is found for th e general form ula for th e current, valid over wide ranges of tem perature an d field stren gth, suggested-by Millilian an d L auritsen (Proc. N at. Acad. Sci., 1 9 2 8 , 14, 4 5 ).
E xception is tak en to th e assertion of these au th ors t h a t th e conduction electrons, unlike th e therm ions, do n o t share in th e therm al energy of ag itatio n of th e atom s. I t is found th a t Sommerfeld’s picture of a m etal yields th e form ula b oth for strong fields and for therm ionic emission, a single set of free conduction electrons distrib u ted according to th e F erm i-D irac statistics sufficing for b o th purposes.
L. L. Bir c u m s h a w. L ib e r a tio n of e le c tro n s f r o m a m e t a l s u rfa c e b y p o s itiv e io n s . F . M. Pe n n i n g (Proc. K . Akad.
W etensch. A m sterdam , 1928, 3 1 , 14—23).—In order to get m ore inform ation as to th e p a r t played by positive ions in a gas discharge, tw o m ethods have been devised for determ ining experim entally th e num ber of positive ions required to liberate one electron from a m etal surface. In neon, th e num ber of electrons liberated b y one positive ion a t zero velocity from a copper or iron surface, is of th e order of 0-05. I n argon a0 is sm aller th a n in neon, b u t a t a m agnesium surface it is larger th a n a t a copper surface. M easurem ents have also been carried out w ith hydrogen to com pare th e m ethod w ith th a t em ployed b y B aerw ald (Ann. Physik, 1921, [iv], 6 5 , 167), b u t, for a p otential of 1000 volts, th e value of a was only 10% of th a t found by Baerwald.
M. S. Bu r r. H y d ro g e n a c tiv a te d b y th e e le c tric d is c h a r g e . A. d e He m p t i n n e (Bull. Acad. roy. Belg., 1928, [v], 1 4 , 8— 17).— See th is vol., 139.
P h o to - e le c tr ic th r e s h o ld a n d h e a t of d is s o c i
a tio n of th e p o t a s s i u m m o le c u le . R . W. Di t c h-
b u r n (Proc. Camb. Phil. Soc., 1928, 2 4 , 320—327).—
A bsorption curves and photo-ionisation experim ents agree an d give for th e m olecular photo-electric threshold value of potassium 2 5 5 5 ^ 2 0 A . The energy of dissociation of th e potassium molecule is O-SOgiO-Ol volt, and th e h e a t of dissociation 11400 g.-cal. Between 200° a n d 500° th e fraction associated varies from 10~4 to 1 0~2.
C. J . Sm i t h e l l s. H ig h -fre q u e n c y e le c tric d is c h a r g e a t lo w p r e s s u r e s . * J . Ta y l o r and W . Ta y l o r (Proc.
Camb. Phil. Soc., 1928, 2 4 , 259—267).—E xperim ents have been carried o u t under widely varied conditions on discharges th rou gh gases, under th e influence of high-frequency oscillations (order 1 0 7 cycles per sec.), using tubes of th e electrodeless typ e. The influence of th e wall m aterial is shown by th e fa c t th a t on pum ping down tubes n o t previously baked out, th e order in which th e discharges were first obtained on increasing th e voltage w a s: soft glass, pyrex, and qu artz. E ven a t th e highest degree of exhaustion an d w ith th e m ercury vapour (from th e pumps) frozen out, faintly lum inous discharges could be obtained. W ith a high frequency of alternation th ere will be no separation of charges, and th e n e tt effect will be a periodic m ovem ent of th e electrons through an atm osphere of positive ions, th e observed lum inosity arising from recom binations proceeding betw een oppositely charged particles. The discharge passes m ore easily in wide tubes th a n in narrow ones, w ith a d ark space between th e glow an d th e wall.
The lum inosity can be conducted along th e tu b e by
6 82 BRITISH CHEMICAL ABSTRACTS.--- A.
moving an earthed conductor such as th e hand along th e outer walls. B y lining th e inside of a tu b e w ith m etal gauze connected to a voltage supply, it is shown th a t th e lum inosity is destroyed by a u n i
p otential wall. Injection of slow electrons into th e glow has little effect. A new ty p e of spherical glow has been obtained in bulbs, and discharges of this kind are regarded as uniform high-tcm perature enclosures of electrons an d positive ions m aintained
artificially. R . A. Mo r t o n.
E le c tr o d e le s s d is c h a r g e t h r o u g h g a s e s . J . J . Thomson (Proc. Physical Soc., 1928, 4 0 , 79—89).—
An electrodeless discharge is produced by placing outside a glass tube containing gas a t a low pressure a solenoid connected to the outsides of tw o Leyden jars, th e insides of which are connected to the term inals of an induction coil. R apidly alternating currents pass through the solenoid, and the electro
m agnetic induction starts currents in th e exhausted vessel w hich flow in rings co-axial w ith the solenoid.
The theory of the discharge is discussed. There is a critical gas pressure, depending on the frequency, at which the discharge passes m ost easily. W ith heavy currents the m agnetic force is greatest near the walls of the bulb and produces a condition resem bling the H eaviside layer. The discharge is assisted by the action of light, which is attributed to the absorption of energy by the gas molecules rendering them more easily ionised. The effect of impurities in the bulb is investigated. Free electrons become attached to electronegative elem ents like phosphorus and sulphur and ionisation is reduced. Metals also hinder the discharge b y combining w ith gas m olecules which are in a more active state th an normal. The normal oxides of m agnesium, calcium , and zinc combine w ith oxygen under the influence of the discharge to form
higher oxides. C. J. Smithells.
E x c ita tio n of th e D -lin e s b y th e g r e e n s o d iu m b a n d . E . L. K i n s e y (N ature, 1928, 121, 904—
905).—In accord w ith th e views of W ood and K insey (this vol., 687), th e green sodium b and excites the .D-lines in pure sodium vapour, b u t only in a narrow tem perature ra n g e ; th e atom ic lines appear som ewhat below 400°, are m axim al a t 410°, and disappear above 450°. A t 410° th e molecules are probably only 55% dissociated. A. A. E l d r i d g e .
S p a c e -d is tr ib u tio n of th e p h o to -e le c tro n s e je c te d b y A '-rays. E . C. Wa t s o n (Physical Rev., 1928, [ii], 3 1 , 728—741).—R u th erfo rd ’s theory of nuclear scattering, together w ith the assum ption th a t all th e electrons s ta rt from the p aren t atom in th e same direction, accord w ith the observed distribution of the photo-electrons ejected b y X -rays.
A. A. El d r i d g e. P h o to - e le c tr ic effec t a n d th e r m io n ic e m is s io n . P. W. Br i d g m a n (Physical R ev., 1928, [ii], 31, 862— S66).—A correction and extension of previous w ork (this vol., 213). A. A. El d r i d g e.
V o lta g e - in te n s ity r e la tio n s in th e m e r c u r y s p e c tr u m . W. D. Cr o z i e r (Physical R ev., 1928, [ii], 3 1 , 800—811).—V oltage-intensity curves were obtained for 2 0 m ercury lines, when excited by elec
tro n im pact. There is no significant change in the
num ber of atom s in a given energy sta te as the ionisation p o ten tial is passed. The probability of different transitions down from a given energy state m ay n o t be independent of th e w ay in which this s ta te is excited. A. A. El d r i d g e.
S e r ie s a n d io n is a tio n p o te n tia ls of th e e le m e n t s of th e ir o n g ro u p . H . N. Ru s s e l l (Astro- phys. J ., 1927, 6 6, 233—255).—Series, usually of two m em bers only, have been identified in th e arc spectra of potassium , calcium, scandium , titanium , vanadium , chromium , manganese, iron, cobalt, nickel, copper, zinc, an d in th e spark spectra of calcium, scandium , titanium , manganese, nickel, copper, an d z in c ; approxim ate series lim its are determ ined an d ta b u lated. F ou r im p o rtan t modes of ionisation of the n eutral atom and three for th e second ionisation are indicated. The following principal an d second ionis
ation potentials are recorded : potassium 4-32,
— ; calcium 6-09, 11-82; scandium 6-57, 12-80;
titan iu m 6-80, 13-60; vanadium 6-76, 14-7; chromium 6-74, 16-6 ; m anganese 7-40, 15-70 ; iron 7-S3, 16-5 ; cobalt 7-81, 17-2; nickel 7-64, 18-2; copper 7-69, 20-34; zinc 9-36, 17-89. New high term s, arising from configurations involving a 5« electron, have been identified in th e spectra of vanadium , m an
ganese, cobalt, and ionised m anganese.
A. A. El d r i d g e. A s tro p h y s ic a l e s tim a te s of io n is a tio n p o te n t i a l s of iro n , y t t r i u m , a n d l a n th a n u m . A. V.
Do u g l a s (N ature, 1928, 1 2 1 , 906).—Ionisation potentials are estim ated, from astrophysical d ata, to have the following values : iron, 6 -6 (by comparison w ith scandium and titanium ), 5-5 (by com parison w ith stron tiu m and b a riu m ); y ttriu m , 6 -6 ; lan th an u m , 4-9 volts. ” A. A. El d r i d g e.
I o n is a tio n b y m e t a s t a b l e a to m s . F . M. Pe n
n i n g (Naturwiss., 1927, 1 5 , 818; Chcm. Zentr., 1928, i, 155).—The condition for the reduction of the sparking potential of an in ert gas for large values of pel (pressure X separation of electrodes) on adm ixture of another gas is Vmtl> V i’ ( F met= e x c ita tio n p otential of th e m etastable form of th e in ert g a s ; F,-»^ionisation p otential of th e adm ixed gas). The explanation is based on th e scheme : m etastable atom -[-foreign a to m = n o rm a l a to m + foreign ion.
M easurem ents were m ade on neon w ith adm ixed m ercury, krypton, argon, hydrogen, an d nitrogen, an d on argon w ith adm ixed iodine, m ercury, xenon, and k ry pton . A. A. El d r i d g e.
C u r r e n t d e n s ity of th e n o r m a l c a th o d e fa ll.
W . d e Gr o o t (Naturwiss., 1927, 1 5 , 818; Chem.
Zentr., 1928, i, 155).—The curren t density was sm aller in a m ixtu re of neon (containing 30% of helium) an d argon (0-1—2%) Jthan in th e separate gases; two types of discharge were observed.
A. A. El d r i d g e. L o ss of c h a r g e of p o s itiv e r a y s a n d th e in flu e n c e of n e ig h b o u r in g m e ta llic w a lls . E . Ru c h a r d t (Z. Physik, 1928, 4 8 , 594—599).—
Polemical. A reply to Koenigsberger (A., 1927,
806). J . W. Sm i t h.
•M ob ilities of th e p o s itiv e io n s f o r m e d b y a lp h a - r a y s in a ir , h y d ro g e n , a n d h e liu m . J . S . Ro g e r s
(Phil. Mag., 1928, [vii], 5, 881—903).—From th e
GENERAL, PHYSICAL, AND INORGANIC CHEMISTRY. 68 3
experim entally observed decrease in th e m obility of ions during their life i t is concluded th a t an ion, in a very short tim e after its form ation, has developed into a cluster. The m obility changes in definite steps.
If th e changes in m obility were due to th e gradual addition of n eu tra l molecules, a gradual change in the m obility w ith the life of th e ion would be expected.
This step change in m obility is unexplained.
W. E. Do w n e y. M e a s u r e m e n t of d is p la c e m e n ts of n e g a tiv e c a r r i e r s in fla m e s . E . Ma r x and P . Ka b p l e r
(Physikal. Z , 1928, 2 9 , 261—269).—A flame is charged w ith solutions of alkali m etal salts and th e variation of th e “ displacem ent ” K 2 , where iiY = pX2 (p being the charge-num ber and K 2 the mobility) w ith th e concentration c determ ined. I i 2 varies as (1 /c )i+ c o n sta n t, and the m agnitude AY x (at. wt.) * is th e same for rubidium , potassium , and sodium a t a given n o rm a lity ; lithium is anomalous.
R . A. Mo r t o n. R e fle x io n of e le c tro n s b y a c r y s ta l of n ic k e l.
C. J . Da v is s o n an d L. H . Ge r m e r (Proc. N at. Acad.
S c i, 1928, 1 4 , 317—322).—In continuation of p re vious w ork (A , 1927, 492), an electron beam was directed against a {1 1 1} face of a nickel crystal a t various angles of incidence, and th e intensity of scattering in th e incidence plane m easured as a function of bom barding p o ten tial an d direction.
W henever the speed of th e incident electrons is com prised w ithin any of certain ranges, changing in location as th e angle of incidence is varied, a sharply- defined beam of scattered electrons issues from the crystal in th e direction of regular reflexion. In each of these ranges there is an optim um speed where the in ten sity of th e reflected beam is a m axim um . The phenom enon is th e analogue of th e regular selective reflexion of X -rays, b u t th e Bragg form ula does not hold, although there is a simple correlation between the observed positions of th e m axim a and th e positions calculated by th e Bragg form ula. A. J . Me e.
L u m in o u s b e a d s of m e t a l p a r tic le s s p u tte r e d b y d is r u p tiv e d is c h a r g e in m a g n e tic field . H.
Na g a o k a and T. Fu t a g a m i(Proc. Im p. Acad. Tokyo, 1928, 4 , 106—108).—P hotographs are given showing th e peculiar beaded track s of m etal particles sp uttered in a m agnetic field. Various explanations of the phenom ena are offered, the m ost probable cause being th e altern ate form ation and loss of an oxide film on the surface of th e particle. C. J . Sm i t h e l l s.
R e la tio n b e tw e e n c o lo u r a n d m a g n e ti s m of io n s. B. Ma l y s c h e v (Ann. Physik, 1928, [iv], 85, 794).—In connexion w ith th e w ork of Joos (A , 1927, 94) it is suggested th a t th e investigation of th e magnetic susceptibilities of th e carbonyls of p a ra magnetic m etals in the gaseous, liquid, and solid states should prove interesting. R. A. Mo r t o n.
R a d ia tio n s e m itte d a t th e i m p a c t of h y d ro g e n c a n a l r a y s o n m e ta ls . C . Ge r t h s e n (Ann. Physik, 1928, [iv], 8 5 , 881— 912).—The possibility of exciting characteristic radiations by m eans of th e im pact of canal ray s on m etals has been investigated (cf. A., 1926, 655). Optical reflexion from a concave m irror makes possible th e detection of weak rays em itted from th e points of im pact, b u t it has n o t proved
possible to decide w hether the rays are characteristic radiations from th e atom s of th e surface, or w hether th ey correspond w ith th e excitation of th e L ym an series. The effects observed by Thomson (A , 1926, 988) are ascribed to reflected canal rays. An experi
m en t designed to separate th e w ave-radiation effect from th e reflected positive-ray effect showed th a t some of the canal rays are scattered with alm ost unchanged velocities. These reflected rays increase in velocity as th e velocity of th e prim ary rays increases. The scattering from different m aterials follows the laws for th e scattering of a-particles a t atom ic nuclei, nam ely, proportionality with the num ber of atom s per c .c , and w ith th e square of the atom ic num ber. R . A. Mo r t o n.
P o s itiv e - r a y a n a ly s is of w a t e r v a p o u r io n is e d b y i m p a c t of s lo w e le c tro n s . H . A. Ba r t o n and J . H . Ba r t l e t t, jun. (Physical R ev., 1928, [ii], 3 1 , S22— 826).—B y th e use of an electrom agnetic m ethod th e ions H20 ; an d O H + were detected, the form er being th e more ab un dant, w ith small quantities of a th ird ion, probably H30 ! ; no negative ions were observed, an d scarcely an y H + an d H 2+ ions. The ionisation p otential corresponding w ith H 20 1 was 1 3 ± l-5 volts, and th a t of O H + W as n o t distinguish- ably different. The H20 + ion is probably th e p rim ary ion. A. A. El d r i d g e.
D e te c tio n a n d d e te r m in a tio n of io n s in a g a s e o u s d is c h a r g e b y o p tic a l m e th o d s . W . d e. Gr o o t and L. Bl o k (Physica, 1927, 7, 315—320).—
L ig ht from a carbon arc passes throu gh an are form ed in neon between a tun gsten cathode an d a nickel anode w ith a barium c o re ; th e light from the carbon arc is cu t off in phase w ith an alternating, cu rren t superim posed on th e direct current for the barium arc, so th a t th e absorption effects can be observed during those periods when th e barium arc is extinguished. The barium lines 4934 an d 4554 were observed in absorption. A positive-colum n discharge tu b e w ith argon and m ercury vapour showed th e m ercury line 2847 A . a t 20° and —12°, b u t n o t a t 120°. The absorption is dependent on th e effective num ber of absorbing atom s and the thickness of th e absorbing layer. F o r barium , the num ber of ions per c.c. a t 3 am p. arc current is 1012.
Ch e m i c a l Ab s t r a c t s. I o n is a tio n in p o s itiv e -io n s h e a th s . P . M - Mo r s e an d W . Uy t e r h o e v e n (Physical R e v , 1928,.
[ii], 3 1 , 8£7—832).—The positive-ion curren t to a plane auxiliary collector placed in a neon discharge is double th a t an ticip ated ; th e increase is probably caused by th e ionisation of th e m etastable atom s w ithin th e sheath by rad iatio n from th e discharge..
A sim ilar increase is to be expected in helium and
argon. A. A. El d r i d g e.
A c tiv e n itr o g e n . J . Ka p l a n and G . Ca r i o
(N ature, 1928, 1 2 1 , 906—907).—The long life and behaviour in th e presence of catalysts of active nitrogen indicates th a t it is atom ic, and th a t m eta
stable molecules are formed under the influence of th e recom bination of atom s to molecules. This process is considered to be accom panied by th e form atio n of m etastable atom s. This view is shown to be in accord w ith experim ental d ata. A. A. El d r i d g e.
6 8 4 BRITISH CHEMICAL ABSTRACTS.— A.
A c tiv e n itro g e n . B. Le w i s (N ature, 1928, 121, 864— 865).—Polemical an d explanatory (cf. Willey, th is vol., 341). A. A. El d r i d g e.
A ctiv e n itr o g e n . B. Le w i s (N ature, 1928, 121, 938—939).— On introduction of pure oxygen (1%) in to glowless nitrogen im m ediately after discontinuing th e electrodeless discharge, no glow was produced;
furth er, subsequent subjection of th e m ixture to th e discharge caused little or no glow. The observation accords w ith those of H erzberg (this vol., 457) and of Bonhoeffer and K am insky (A., 1927, 801). Intense nitrogen after-glows have been obtained in m ixtures containing up to 57% of oxygen in th e electrodeless discharge a t or below 0-2 m m . pressure. A t higher pressures th e ty p e of afterglow changes, u n til a t abo u t 1 m m . and up to 2 m m. (in air) only th e con
tinuous after-glow spectrum of oxygen is observed.
A. A. El d r i d g e. N itr o g e n a fte r-g lo w . S. P . McCa l l u m and W. E . Pe r r y (N ature, 1928, 121, 942).—A nitrogen after-glow appears when a discharge is passed through a m ixture of air and argon a t low pressures;
th e relative proportions of th e m ixture m ay be varied over a fairly wide range. M ixtures of neon and helium are ineffective. A. A. El d r i d g e.
A c tio n of 1 ‘ a c tiv e n itr o g e n ’ ’ on io d in e v a p o u r . L. H . Ea s o n an d R . W. Ar m o u r (Proe. R oy. Soc.
E din., 1928, 48, 1—9).—The spectrum of iodine excited b y active nitrogen was investigated and, in addition to th e iodine line a t 206 ;iy., a line a t 185 ¡¿ix was found. I n order to dissociate th e iodine and raise th e atom to the level of electronic energy required to em it th is line, a to ta l of 189,000 g.-cal., or S-4 volts, is necessary. There m ust therefore be some form of nitrogen present capable of supplying th e energy.
The high energy level can be accounted for on th e view th a t the glow is produced b y th e com bination of atom s of nitrogen. A n experim ent was conducted to find w hat pressure of iodine vapour was required to increase th e velocity of “ reaction ” betw een the iodine and the nitrogen so th a t simple decay could be neglected. I t is concluded from th e fa ct th a t th e pressure of iodine required to produce practically nothing b u t iodine glow is of the order of 1 /15th p a rt of th e active nitrogen present, and th a t th e glow is practically instantaneous, th a t chemical action is very unlikely, an d th a t th e iodine receives energy and radiates i t over and over again. The view is confirmed b y the fact th a t even w ith pressures of iodine 1 /1250th p a rt of th e p artia l pressure of active nitrogen, there is still a decided photographic effect due to th e iodine. By attem pting to m easure th e duration of th e glow by m eans of a kinem atographic cam era it was found th a t when th e pressures of iodine vapour and of active nitrogen were of th e same order th e glow did n o t last for more th a n 0 -0 1 sec.
A. J . Me e. C h e m ic a l a t. w t. d e te r m in a tio n a n d t r u e a t.
w t. G. Ki r s c h (Naturwiss., 1928, 16, 334—335).—
A discussion of th e discrepancy between th e chemically determ ined a t. w t. of radium -(? an d th a t deduced from th e disintegration series an d of th e difficulty of reconciling these w ith th e a t. w ts. of lead found by
A ston. J . W . Sm i t h.
A t. w t. of a c tin iu m -le a d , t h e l a s t m e m b e r of t h e a c tin iu m s e r ie s . F . Lo t z e (Z. anorg. Chem., 1928, 170, 213—221).—The published a t. w t. d eter
m inations w ith lead of purely radioactive origin, and therefore consisting of radium -6-', thoriu m -/), and actinium -D , have been exam ined. Calculating th e am ounts of thorium -D an d radium-C? from th e proportions of thorium an d uranium , respectively, in th e original m inerals, th e m ean value of 207 is obtained for th e at.- w t. of actinium -D . R . Cu t h i l l.
S e p a r a tio n of is o to p e s of p o ta s s iu m . / G. von He v e s y and M. Lo g s t r u p (Z. anorg. Chem., 1928, 171, 1— 13).—B y subjecting potassium to th e process of ideal distillation (cf. A., 1922, ii, 149), a residue was obtained having at. wt. 39-109, corresponding w ith an increase of 4-8% in th e proportion of th e isotope K 11. As th e radio activ ity increased a t th e same tim e by 4-2%, it is concluded th a t th is isotope is probably responsible for th e radioactivity of
potassium . R . Cu t h i l l.
D e te r m in a tio n of is o to p e s b y s p e c tr a l lin e s . E . K . Pl y l e r (J. E lisha M itchell Sci. Soc., 1927, 43, 24).—The b and sp ectra of sulphates of isotopes are m ultiple. Nickel, potassium , an d m agnesium con
tain , respectively, 2, 2, and 3 isotopes.
Ch e m i c a l Ab s t r a c t s. P u r if ic a tio n of r a d o n . L . We r t e n s t e i n (Phil.
Mag., 1928, [vii], 5, 1017— 1027).—An all-glass ap p aratu s in which rad on preparations of high p u r it}' m ay be m ade is described. Purification is effected by the usual reagents, copper oxide, copper, potassium hydroxide, and phosphoric anhydride, and condensing th e gas b y liquid air. Pressures are m easured by m eans of a calibrated K nudsen gauge.
E v acu atio n is effected b y a m ercury diffusion pum p, and in order to avoid contam ination w ith h y d ro carbons from , ta p grease a m ercury seal is em ployed to isolate th e ap p a ratu s from th e pum p. Considerable difficulty was encountered in rem oving th e la st traces of carbon dioxide. I t is concluded th a t carbon dioxide is th e only gas left as an im pu rity. In general quantities of rad on of th e order of 50— 100 millicuries can be concentrated b y th is m ethod so th a t th ey contain only 20—50% of carbon dioxide.
A . E . Mi t c h e l l. R a n g e s of th e a - p a rtic le s of u r a n i u m I a n d II . G. C. La u r e n c e (Phil. Mag., 1928, fvii}, 5, 1027—
1038).—A m ore detailed account, based on a g reater num ber of observations, of previous w ork (this vol., 4) is given. The ranges of th e a-particles from uranium I and uranium I I were found to be respect
ively 2-73 an d 3-28 cm., a t 150° and 760 m m . These results are in close agreem ent w ith th e prelim inary determ inations and th e probable error is less th a n 1% . The decay co nstant of uranium I I calculated from th e above figure is 1-7 X 10~12 sec.-1, equivalent to a half- life period of 13,000 years. A . E . Mi t c h e l l.
F o r m a t i o n of a g a s e o u s h e lid e of r a d i u m a c tiv e d e p o s it. D. M. Mo r r i s o n (Proc. Camb. P hil. Soc., 1928, 24, 268—275).— On th e assum ption th a t th e helium atom can exist in hydrogen-like form, in which one electron is relatively far from th e nucleus, th e form ation of com pounds corresponding w ith hydrides m ay be expected. Helium was passed over
