BRITISH CHEMICAL ABSTRACTS
A.-PURE CHEMISTRY
O C T O B E R , 1927.
G en eral, P h y sic a l, and
H o t-c a th o d e v a cu u m d isc h a r g es in g a s e s and th e vap o u rs of m e ta ls, p a rticu la rly iron , and th eir ap p lica tio n to sp ectro sco p y . K . L. Wo l f
(Z. Pliysik, 1927, 44, 170— 189).—A vacuum furnace is described in which a pure graphite cylinder heated electrically serves both as the hot cathode and the container for the material of which the spectrum is to be examined; the power consumption increases from 2-6 kilowatts at 1225° to 10-2 at 2155°. A variable D.C. potential (maximum 110 volts) is applied between the hot cylindrical cathode and a graphite anode placed near to one end of the cathode.
No appreciable emission was detected below 1750°;
currents of the order of 20 amp. at 30 volts are readily obtained at a temperature of 2000° when a small amount of pure iron is placed hi the centre of the cathode. A number of photographs are given which illustrate the character of the iron spectrum so produced; in particular the lines are very clear and narrow and the method is therefore especially suitable for accurate measurements. Very satis
factory argon spectrograms are obtained when argon is streamed through the apparatus. I t is also shown that the apparatus is readily adaptable for the deter
mination of the influence of gas pressure on the nature of the spectrum of the vapour of a metal such
as non. R. W. L u n t .
Quartz d oub le m o n o ch ro m a to rs and a s im p le new flu orite v a cu u m sp ectro g ra p h for th e Schum ann re g io n . C. L e i s s (Z. Physik, 1927, 44, 133—138).—A spectrograph suitable for the range 1850—1000 A. is described. R. W. L u n t .
Q uantitative s e n sitiv ity of sp ectra l lin e s. T.
Negrf.sco (Compt. rend., 1927, 185, 453—455).—
The relations between the concentrations of metals in alloys and the intensities of then spectral lines have been investigated for arc, flame, and oscillating spark spectra. With diminishing concentration of the metal the intensities of all its lines diminish con
tinuously, and disappear in the same order as with the pure metal itself under the same conditions.
Diminution of the quantity of an element in a source pf light diminishes the intensities of all the lines, independently of the potential necessary for their
production. C. W. Gib b y.
True and ap p aren t w id th of sp ectra l lin es.
H. C. B u rg er and P. EL van C it t e e t (Z. Physik, 1927, ^ 44, 58—69).—Following a mathematical analysis, the use of a Fabry-Perot interferometer for the measurement of the true width of spectral lines is described. The width of the cadmium line 6439 A.
3 o 909
In o rg a n ic C h em istry .
so determined at approximately 390° is 0-0114 0-0008 A., whilst the calculated width due to Doppler effect produced by thermal agitation is 0-0107 A .;
the width is thus due almost solely to Doppler effect.
R. W . Lu n t.
N e w re g u la r itie s in a to m ic sp ectra. J. C.
M c L e n n a n - and A. B. M c L a y (Phil. Mag., 1927, [vii], 4, 407— 413).—From an examination of the arc spectra of the elements the authors have observed a well-defined periodicity in the progression of frequency with atomic number in each period of the periodic classification, and also a similarity in the periodicities of each of the periods. A. E. M i t c h e l l .
A b so rp tio n lin e s of th e so la r sp ectru m . H.
v o n K l u b e r (Z. Physik, 1927, 44, 481—516).—An elaborate analysis of the optics of the absorption of lines in the solar spectrum is given, and data referring to the intensity distribution and half width of the following lines are tabulated : H a, sodium 6154-438, 6160-596; calcium 6102-937, 6161-503, 6162-390, 6163-968, 6166-651, 6169-249, 6169-778; iron 6200-527,
6219-494. R. W . L u n t .
N u clea r v ib ra tio n in th e b and sp e c tr u m of h eliu m . W . W e i z e l and C. F u c h t b a u e r (Z.
Physik, 1927,4 4 , 431-—454).—The spectrum produced by damped wave-train discharges in a stream of helium has been exam ined; a number of new bands characteristic of the Hea molecule have been observed associated with the vibration transitions 0 —1 and
1—1. R. W. Lttnt.
N u m er ica l evalu ation b y w a v e m e ch a n ics of th e m e a n v a lu es of th e o rth o - an d p a ro -term s of H e and L i + fro m p o la r isa tio n te r m s. Y. S u g i u b a
(Z. Physik, 1927, 44, 190—206).—The mean value of the ortho- and jjom-terms has been evaluated numeric
ally by solving Schrodinger’s equation for the central field. This analysis leads to the following values for the distance between the outermost components of the fine structure lines : lie , Av2i,=0-86 cm.-1 (ob
served 1-07); Li+, Av2p= 4-25 cm.-1 (observed 4-4);
the agreement is considered to be satisfactory.
R. W . Lu n t.
T ra n sitio n of g lo w in to a rc d isc h a r g e in n itrog en . M. W e h e l i (Z. Physik, 1927, 44, 301—
318).—The current-potential, arc length-potential, and pressure-potential characteristics have been determined for the direct-current discharge between tungsten electrodes (diameter 1-7 mm.) in pure nitrogen. Neither chemical action nor melting of the electrodes was observed; at pressures above 181 mm. the transition from glow to arc discharge
910 BRITISH CHEMICAL ABSTRACTS.— A.
is continuous and independent of the distance between the electrodes; below 104 mm. regions of instability are observed in which both glow and arc discharge can exist at a given value of the current; below 20 mm. increase in the current strength fails to effect the transition. Reproducible results cannot be ob
tained if nitrogen is contaminated with oxygen or water vapour, the discharge becoming unstable.
R. W. Ltjnt. W ave-length of th e g reen au roral lin e in th e ox y g en sp ectru m . J. C. M cLennan and J. H.
McLeod (Proc. Roy. Soc., 1927, A , 115, 515—527).—
The wave-length of the oxygen green line, determined by means of a Fabry-Perot interferometer, is found to be 5577-34:1 ¿0-004: A. This is in excellent agreement with Babcock’s value for the wave-length of the auroral green line, 5577-350+0-005 A. (Astro- phys. J., 1923, 57, 209), and confirms the view advanced by McLennan and Shrum that the green auroral line has its origin in oxygen in the upper atmosphere (cf. A., 1924, ii, 642).
L. L. Bi r c u m s h a w.
R e g u la ritie s in th e sp ectru m of io n ised neon.
P. K . K i c h l u (Proc. Physical Soc., 1927, 39, 424—
428).—Numerous lines in the spectrum obtained by passing a condensed discharge through the more volatile gases of air have been attributed to singly- ionised neon. An analysis is made which confirms the identification for the lines within the limits 7282 and 3142 A., and is in strict accord with Hund’s
theory. R. A. M o r t o n .
S p ark sp ectru m of neon, N e II. X. T. L. d e Br u i n (Z. Physik, 1927, 44, 157— 161).—A scheme of energy levels for ionised neon is advanced whereby some 200 lines of the spark spectrum have been co
ordinated; it is in complete agreement with Hund’s theory. The quadruplet terms associated with the lower energy levels and the analogies to be traced with the arc spectrum of fluorine are dealt with in
detail. R. W. Lu n t.
S p ectra of m e ta llic a rcs sta r ted in ch lorin e.
M. Mi y a n i s h i (Mem. Coll. Sci. Kyoto, 1927,10, 273—
277).—The spectra of metallic arcs and of flames from an electric furnace have been studied when the arc and furnace chambers contained an atmosphere of chlorine. The presence of chlorine causes the appearance of some super-spark lines and the enhance
ment of spark lines in the arc. The flames from the furnace also exhibit spark lines in an atmosphere of
chlorine. R. A. Mo r t o n.
S p e ctr u m of a rgon in th e ex tr e m e u ltra violet. F . A. S a u n d e r s (Proc. Nat. Acad. Sci.,
1927,13, 596—600).—A number of lines in the portion of the argon spectrum from 894 to 797 A. still require explanation. The possibility that some of the lines are due to collisions between metastable neon atoms and neutral argon atoms is considered, but the balance of evidence seems to indicate that some members of the argon series are present although certain variations in intensity must be left for further study.
The four lines 8S7, 883, 875, and 871 A. are due to a pp' group in the spectrum of A in . The neon spectrum shows a group of lines between 661 and 680 A. which include the three nconpj)’ combinations,
whilst the rest of the group is probably part of the A in spectrum. The inclusion of 932 and 919 in the A I spectrum is of doubtful validity.
R. A. Mo r t o n.
D isp la c em e n t of certain m u ltip le ts and m u lti
p le le v e ls for e lem en ts in th e fir s t lo n g p eriod . R. C. Gi b b s and H. E. Wh i t e (Proc. Nat. Acad. Sci., 1927, 13, 525— 531).—The irregular doublet law, together with the regular displacement law of multi
plets, has enabled the approximate spectral position of multiplets of Cr in and Mn m arising from the electron transitions 3d34p to 3fZ34s and SdHp to 3d44s to be located. Lande’s interval rule in con
junction with the regular doublet law has enabled certain frequency differences to be picked out. The analysis has been extended through successively increasing iso-electronic systems as far as those of the Cu i, Zn n type. The regular displacement of multiplets and the displacement of multiple levels are shown diagrammatically for the entire group.
On the Moseley diagram any term (taken with respect to its limit) in a sequence of iso-electronic systems should reveal a relation very nearly linear (cf. this
vol., 601). R. A. Mo r t o n.
A b so rp tio n sp ectra of iron , n ick el, and cobalt.
W . F. Me g g e r s and F. M . Wa l t e r s, jun. (U.S. Bur.
Standards Sci. Paper 551, 1927, 22, 205—226).—
The high-potential under-water spark spectra of iron, nickel, and cobalt has been re-examined using a grating spectrograph; 265 iron lines (2166— 4404 A.), 225 nickel lines (2124—3858 A.), and 340 cobalt lines (2137— 4120 A.) which are absorbed in the source have been recorded and classified. The majority of these lines are identical with the stronger lines of the arc emission spectra, and involve the normal state, or some low metastable state of the neutral atom.
The results confirm an earlier conclusion that the normal state of the iron atom is represented by a quintuplet-!) term, that of cobalt by a quadruplet-i1 term, and that of nickel by a triplet-f1 term.
R. W . Lu n t.
A rc sp ectru m of copper. P. K . Ki c h l u (Indian J. Physics, 1927, 1, 401— 412).—The arc spectrum of copper, recently analysed by a number of investig
ators, is discussed. Several new lines, obtained with an arc of current 20—30 amp., are also described.
M. S. Bu r r.
L en g th s of en h anced lin e s of m e ta ls excited in v a rio u s m e d ia an d lin e s of co n sta n t w ave- n u m b e r d ifferen ces a m o n g en h anced lin e s of b ism u th an d lead . M. Mi y a n i s h i (Mem. Coll. Sci.
Kyoto, 1927, 10, 263—272).—The spark spectra of copper, zinc, aluminium, lead, bismuth, chromium, manganese, and nickel have been produced in atmo
spheres of hydrogen, water vapour, nitrogen, oxygen, chlorine, bromine, and iodine. The changes which occur in the appearance of enhanced lines provide a method for classifying lines into spark, super-spark, and arc spectra. In hydrogen, the lengths of super
spark and super-super-spark lines were much greater than in the air spark; in water vapour the increase in length was small; in nitrogen and oxygen no change was observed. In an atmosphere of halogen spark lines were enhanced but super-spark lines de
creased in length and intensity. The shortening of super-spark lines with change in medium occurred in the order hydrogen (longest lines), water vapour, nitrogen, oxygen, halogen. Lines having constant wave-number differences are recorded among the enhanced lines of lead and bismuth.
R. A. Mo r t o n.
In sta n ta n eo u s sp e c tr o g r a m s of copper, silv er, an d gold . H. Na g a o k a, D. Nu k i y a m a, and T.
Fu t a g a m i (Proc. Imp. Acad. Tokyo, 1927, 3, 319—
323; cf. this vol., 809).—The spectral lines produced by the passage of a heavy disruptive discharge through electrodes of the above metals are recorded. The general character of the lines is similar in each case, and is not greatly influenced by the nature of the gas in which the electrodes are. R . Cu t h i l l.
In sta n ta n eo u s sp e c tr o g r a m s of zin c, ca d m iu m , an d m ercu ry . H. Na g a o k a, D. Nu k i y a m a, and T. Fu t a g a m i (Proc. Imp. Acad. Tokyo, 1927, 3, 324—
329).—The spectral lines produced by the passage of a heavy discharge through electrodes of the above metals are recorded. With mercury there are two distinct stages of emission, and there are some indic
ations of a similar phenomenon with the two other
metals also. R. Cu t h i l l.
In sta n ta n eo u s sp e c tr o g r a m s of b oron , a lu m in iu m , an d th a lliu m . H. Na g a o k a, D. Nu k i y a m a,
and T. Fu t a g a m i (Proc. Imp. Acad. Tokyo, 1927, 3, 330—333).—The spectral lines observed when a disruptive discharge is passed through specimens of the above metals are recorded. With thallium, the nature of the gas surrounding the electrodes influences reversal, particularly in respect of divergence.
R . Cu t h i l l.
S tru ctu re of th e sp ectra of k ryp ton and xen on . J. C. McLe n n a n and R . Ru e d y (Nature, 1927, 120, 333).—There is selective absorption of spectral lines of krypton and xenon when a weak electrical dis
charge is passed through the gas, examples of lines absorbed being 7601, 7854, 8104, 8112 Â., and 8231, 8819 A., respectively. Analysis of the xenon spec
trum also indicates that the structure of the spectra of krypton and xenon corresponds with that of the spectra of neon and argon. A. A. El d r i d g e.
E lectric fu rn ace sp ectra of y ttriu m , zirco n iu m , and lan th an u m . A. S. Ki n g and E . Ca r t e r
(Astrophys. J., 1927, 65, 86— 107).—The temperature classifications of 451 yttrium, 858 zirconium, and 695 lanthanum lines between 2808 and 7882, 2792 and 8305, and 2799 and 8347 A., respectively, are tabulated, temperatures of 2000—2800° being employed. The lanthanum spectrum contains a large number of close doublets, and some triplets, previously regarded as single lines. A. A. El d r i d g e.
Series sp ectra of silv e r -lik e a to m s. R. J.
La n g (Proc. Nat. Acad. Sci., 1927, 13, 341— 346).—
The identification of the first members of the four ordinary series for In in and Sn iv has been com
pleted (cf. Carroll, A., 1926, 214) and the members for Sb v have been identified. The term values of these and other series were determined. The first principal pair of lines in Te v i were also located.
S. K . Tw e e d y.
S e r ie s in th e sp ectru m of tr eb ly -io n ised tin (Sn iv ). K . R. Ra o (Proc. Physical Soc., 1927, 39, 408— 416).—The spectrum of tin exhibits regularities ascribed to Sn iv, and pairs of sharp and diffuse series are shown, to converge to a common lim it with a sixteen-fold value of the Rydberg constant. The fundamental and super-fundamental series doublets are also indicated, and term values are obtained from the related system of members by assuming a value for the O term. The lines in the tin spark spectrum have been measured with an accuracy of about 0-05 Â.
R . A. Mo r t o n.
S p a rk sp ectru m of cæ siu m . G. B a la s s e (J.
Phys. Radium, 1927, [vi], 8, 311—320).—The spark spectrum of cæsium produced by the electrodeless discharge has been studied. According to the method of E. and L. Bloch (A., 1923, ii, 350), the lines of the spark spectrum can be divided into two groups depending on the conditions of excitation. Arc lines belonging to the series I s— m d have been recognised for the first time, and can be definitely distinguished by their general aspect and by their relation to a continuous spectrum which is also formed at tem peratures above 200°. As a part of the spark spec
trum of the lower order, lines forming multiplets and extending from the ultra-violet region to 3200 Â., establish, in confirmation of the work of Sommer (A., 1925, ii, 4), an analogy between the spark spectrum of cæsium and those of neon and xenon. The lines observed are tabulated. L. S. Theobald.
F orb id d en lin e of m e rcu ry at 2 2 70 Â . in a b sorp tio n . ( Lo r d) Ra y l e i g h (Nature, 1927, 120, 295).
—The forbidden line 2270 A. has been observed in absofption, although the range of conditions for observation is very limited. Hence direct transition from the normal to the metastable excited state of the mercury atom can sometimes occur (cf. this vol.,
607). A. A. El d r i d g e.
E x p la n a tio n of th e in c o m p lete p o la r isa tio n of m e rcu ry reson a n ce ra d iation . W. A. Ma cNa i r
and A. El l e t t (Proc. Nat. Acad. Sci., 1927,13, 583—
584).—Whenever the theories of Breit and Heisen
berg predict 100% polarisation of resonance radiation, l 1^ —23P 1, and smaller values are observed, the depolarisation is shown to be due to the peculiar behaviour of the —0-0256 Â. component.
R . A. Mo r t o n.
P ro d u ctio n of ch a ra c ter istic X -r a y s b y elec
tr o n ic im p a ct. L. H. Th o m a s (Proc. Camb. Phil.
Soc., 1927, 23, 829—831).—Theoretical. The ex
pression obtained by Rosseland (Phil. Mag., 1923, [vi], 45, 65) connecting the ionisation energy of an electron in an atom and kinetic energy of an electron which removes it, is modified by taking into account the velocity of the core electron in its orbit and the increased velocity of the impinging electron due to the atomic field. The modified formula gives better agreement with experimental results.
W. E. Do w n e y.
D isco n tin u itie s in th e ab so rp tio n of X -ra y s by a lu m in iu m (the so -c a lled J -p h en o m en o n ). O.
Ga e r t n e r (Physikal. Z ., 1927, 28, 493—502).—Both the experimental data regarding Barkla’s ./-pheno
menon and the theories put forward to interpret it
912 BRITISH CHEMICAL ABSTRACTS.— A.
are discussed critically (cf. A., 1920, 217, 447, 987).
An attempt has been made to repeat the experiments of Barkla and Watson (this vol., 3) but similar results could not be obtained. R. A. Mo r t o n.
A b so rp tio n of A rrays of lo n g w a v e -len g th . L. H. M a r t i n (Proc. Camb. Phil. Soc., 1927,23,783—
793).—The mass absorption coefficients of iron, nickel, copper, and aluminium over a wave-length range 0-705—1-932 A. have been measured. Homogeneous beams were obtained by crystal reflexion and the absorption coefficients measured by the direct method.
For iron, nickel, and copper, when the X-rays absorbed lie in the range on the short wave-length side of the respective X-absorption discontinuities, the mass absorption coefficients are represented by a relation of the form ¡x/p=&jX2’8 (kt a constant). On the long wave-length side of the ^-discontinuities, and for aluminium throughout the entire wave-length range, the absorption coefficients are given by n/p=k.p?
(k2 a constant). W. E. D o w n e y .
S im p le rad ioactive m e th o d for th e p h o to g rap h ic m e a su r e m e n t of th e in teg ra ted in te n sity of X -ray sp ectra . W. T. Astbury (Proc. Roy. Soc., 1927, A , 115, 640—657).—Details are given of an easily constructed photometric arrangement, in which the photographic plate is replaced by a carbon print, the light by a-rays, and the light-sensitive cell by a simple cc-ray electroscope. This radioactivity photometer has been applied to the determination of the intensity distribution in X-ray crystal photo
graphs, and, with suitable adjustment, it may possibly be made to integrate the X-ray intensity of a crystal reflexion after the manner of the Bragg ionisation- spectrometer. The apparatus has been used to find the intensity ratio CuXa/X(3. In X-ray photographs of the muscovite mica cleavage plane, 1st order : 2nd order : 3rd order=66 : 31 :100, and the ratio CuK a / /v(5 is 6-2 (corrected for absorption). A further test with a double-wedge photograph of the 3rd order K a mica line gave very satisfactory intensity values for the seven steps of the wedge. The apparatus may be made to give a curve showing a relation between X-ray intensity and a-ray intensity which is approximately linear through the origin, and the application of this property to the determination of the integrated intensity of X-ray spectra is dis
cussed. The method of preparing the carbon tissues for the radioactivity photometer is described.
L. L. Bi r c u m s i i a w.
C ritical ¿ -a b so rp tio n of silv er. G. K e lls tr o m (Z. Physik, 1927, 44, 269—27S).—The S values characterising the critical ¿-absorption of silver have been determined using the technique of Molin and Jonsson (this vol., 286). The S values have been ob
tained from.the ratio of values of the constant A in the equation for the true absorption coefficient t, t=u4xc;
thus SLt—A j J A Ll. The following values have been obtained : SZl=3-17, 8^=1-47, 8Xl= l-2 5 .
R. W. Ltxnt. T e r m stru ctu re an d Z eem an effect of th e arc sp ectru m of tin . J. B. Green and R. A. Loring
(Proc. Nat. Acad. Sci., 1927, 13, 347—350).—A pre
liminary paper in which the term structure of the arc spectrum of tin is analysed. The lowest set of energy
levels is ZP. The Zeeman effect is determined for several lines and discussed briefly.
S. K . Tw e e d y.
Z eem an effect an d stru ctu re in th e sp a rk sp ectra of tin . J. B. Gr e e n and R. A. Lo r i n g
(Proc. Nat. Acad. Sci., 1927, 13, 492— 495).— Certain Zeeman patterns of tin are found to arise from com
binations of doublet terms, and from combinations either between triplet terms or between triplet and singlet terms, the two types belonging respectively to the spectra of singly-ionised and doubly-ionised tin. The following lines are classified: 2P 12S 1,
6843-81; 2P X2D2, 5332-91; *Pt *Sv 6453-15; 2P 22D„, 5596-69; 2P 22D~?, 5562-74.
Several lines in the spectrum of doubly-ionised tin have been arranged into a 3P 3D multiplet and a 3P 3S multiplet. The 4618 line is designated sP 0aS v The lines 3765, 3860, 3963, and 4216 have Zeeman effects like those due to combinations between 2P and 2S terms and are probably due to trebly-ionised
tin. R. A. Mo r t o n.
C om p ton effect w ith b ou n d electro n s. Ob
ser v a tio n s w ith clou d -ch a m b er p h o to g ra p h s in argon . F. K i r c h n e r (Ann. Physik, 1927, fivj, 83, 969— 976).—Wilson cloud-chamber photographs indi
cate that Compton recoil electrons in argon exhibit photo-emission of the second kind. When a suffi
ciently strongly bound electron is emitted as a scat
tering electron, an emission similar to the photo
emission along electron tracks recorded by Auger (A., 1925, ii, 175, 618, 730) is observed. The fre
quency with which the emission of two electrons which leads to scattering occurs is much smaller (about 8%) than that in the analogous absorption process (83%); this follows naturally from the fact that the scattering intensity varies as the number of electrons, whereas the influence of the most strongly bound X-electrons predominates greatly in the absorption process. The X-fluorescence for argon is the same for the hard (0-13 A.) X-rays used as for the soft rays used by Auger. The photo-emission is quite unsymmetrical at the wave-length used, the mean emission angle being 73° from the ray direction.
The ranges and direction-distributions for 0-13 A. are given for recoil electrons in argon. R. A. M o r t o n .
S c h r o d in g e r ’s th eo ry an d th e io n isa tio n poten
tia l of h eliu m . G . W. Ke l l n e r (Z. Physik, 1927, 44, 91— 112).— The ionisation potential of helium in volts has been calculated as the difference between the energy content in volts of the normal state (IS) as given by Schrodinger’s differential equation and the ionisation potential of singly-ionised helium, 54-9 volts. The value so obtained, 20-3 volts, is in good agreement with that computed by Uns5ld by a
different method. R. W. Lunt.
E n e rg y r e la tio n sh ip s and io n isa tio n p oten tials of a to m s of th e fir s t ro w of th e p eriod ic tab le in a ll s ta g e s of io n isa tio n . R. A. M i l l i k a n and I. S.
B o w e n (Proc. Nat. Acad. Sci., 1927, 13, 531—535).
—All lines between 2000 and 200 A. emitted by atoms in the first row of the periodic table, in all stages of stripping, are now identified, even the structure of the spectra being accounted for by the Russell- Pauli-Heisenberg-Hund rules. This makes it pos
sible to extend the Moseley diagrams into the region of low atomic numbers. Instead of following Moseley’s procedure of plotting the square root of emitted frequencies against atomic number, it is better to present the diagram as the relation between atomic number and the square root of the frequencies of energy levels, e.g., for stripped atoms (one-electron systems) the energies, spectroscopically determined, necessary to remove an electron from the 2p orbit of the stripped atoms from lithium through carbon.
Similar lines are obtained by plotting the observed energies necessary to remove an electron from the 2p orbit of a two-electron system, a three-electron system, etc. The best way of considering the exten
sion of the Moseley diagram from neon down to lithium is the somewhat irregular line connecting points denoting the energy necessary to detach a
<p electron from a neutral atom, i.e., a sequence of corresponding energy levels in neutral atoms. It is pointed out that the normal oxygen atom can be ionised in twenty-five different ways each represent
ing an ionisation potential different from all the others. The term is therefore without exact meaning unless defined, e.g., as the energy corresponding with the passage from the most stable state of the atom to the most stable state of the ion. The above definition leads to the following values in volts : lithium 5-371, beryllium 9-50, 18-141; boron 8-34, 24-2, 37-786; carbon 11-3, 24-289, 45-5, 64-23;
nitrogen 14-494, 29-56, 47-2; oxygen 13-565, 34-999, 54-8,77-0; fluorine 16-9, 82-3; neon 21-482.
R. A. Mo r t o n.
P r e c isio n m e a su r e m e n t of e / m 0 b y th e m eth o d of H. B u sc h . F. Wo l f (Ann. Physik, 1927, [iv], 83, 849—883; cf. Busch, Physikal. Z., 1922, 23, 438).—Busch’s method has been improved. The mean of 70 determinations of e/m0 is (l-767g±
0-0018) X107 e.m.u. The maximum error is ±0-2%
and the mean error about 0-07%. W. E. Do w n e y.
E xcita tio n of h ig h -v e lo city electron s. E. G.
Dy m o n d (Proc. Camb. Phil. Soc., 1927, 23, S04—- 810).—The visible helium spectrum has been excited by means of high-velocity electrons. The variation in intensity of the various lines due to excitation by electrons of different velocities was measured. The bearing of these results on the various theoretical views of excitation is discussed. W. E. Do w n e y.
E lectron v e lo c itie s in th e n o r m a l an d selectiv e photo-electric effect. P. Wo l f (Ann. Physik, 1927, [iv], 83, 1001— 1053).—The velocity of electrons liberated in the selective photo-electric effect, using wave-lengths from 365 to 546 |x[j. on potassium- sodium alloy, is substantially the same as the velocity for the normal effect, although the numbers of electrons liberated in the two cases differ enormously.
The electron velocity varies with the frequency of the light in exactly the same way for the selective as for the normal effect, a conclusion valid for a large range of angles given on the one hand by the normal to the irradiated surface and the direction of electron release, and on the other hand by the emergence- direction and the electric vector of the light for the selective effect. Although the electron velocity is substantially the same for the two effects, the values
for the selective effect are very slightly (0-02—0-03 volt) higher than those for the normal effect. The difference appears to be real. The breadth of the velocity-range increases steadily with the period of the light for the selective effect, but a maximum is shown at 400 ¡xjx for the normal effect. The gradual decrease in photo-electric sensitivity which occurs with time progresses more rapidly for the selective than for the normal effect. The contact P.D. between the potassium-sodium alloy and brass has been specially investigated and has been shown to rise at first rapidly from 1-7 to 2-1 and then more slowly to about 2-6 volts. Approximate values for the velocities of electrons leaving the surface have been calculated in absolute units. Electron velocities and frequencies are linearly related for both effects as investigated. R. A. Mo r t o n.
V ariation in th e v elo city d istrib u tio n of p h o to elec tric electro n s w ith o u tg a s s in g an d g a s s in g p r o c e sse s w ith p a lla d iu m and p la tin u m . W.
Be n n e w i t z (Ann. Physik, 1927, [iv], 83, 913— 940).
—The photo-clectric properties of palladium and platinum have been determined for a considerable number of samples of pure metal foil differing only in respect of gas content. The outgassing process was interrupted at various stages and finally carried as near to completion as possible and at the other end of the scale the metal was left in contact with oxygen, hydrogen, or a h for one night. Values for the following magnitudes were obtained in each case : photo-electric sensitivity, maximal volt velocity (voltage necessary to reduce the velocity of the fastest electrons to zero), mean volt velocity (a magni
tude taking into account the velocity distribution), contact P.D., and the long-wave limit (threshold).
If the values were plotted in the same order of samples the variation of each magnitude followed a quali
tatively similar course; the results were throughout in agreement with Einstein’s equation. In three sets of experiments the electron velocity when the number of electrons liberated reached a maximum differed b y about the same amount from the maximal velocity.
With palladium there are two maxima in the velocity distribution curves, one predominating at small sensitivity values and the other steadily increasing in importance as the sensitivity increases. Platinum, on the other hand, exhibits only a small shift in the maximum (towards the side of maximal velocity) with increashig sensitivity. R. A. Mo r t o n.
S p ace d istrib u tio n of th e p h o to -electro n s ejected b y A'-rays. E. C. Wa t s o n (Proc. Nat.
Acad. Sci., 1927, 13, 584— 588).—The theory of nuclear scattering, together with the assumption that the electrons all start from the parent atom in the same direction, explains in a satisfactory way all the details of the observed space distribution of the photo-electrons ejected by X-rays. R. A. Mo r t o n.
S u rface la y ers on tu n g ste n p ro d u ced b y a ctiv e n itrog en . C. Ke n t y and L. A. Tu r n e r (Nature, 1927, 120, 332).—A clean tungsten surface at a dull- red heat, if placed in an atmosphere of nitrogen activated either by a condensed discharge or by electron bombardment at more than 22 volts, appears to become covered with a layer of nitrogen of the
914 BRITISH CHEMICAL ABSTRACTS.— A.
order of one atom deep, and the surface is cooled.
At relatively high temperatures the layer is probably so unstable that only a small fraction of the surface can be covered at any moment. The flashing of a covered filament in the neighbourhood of a clean fila
ment causes the production of a layer on the latter.
I t is suggested that active nitrogen may be produced by the bombardment of gaseous nitrogen with 22-volt electrons. A. A. El d r i d g e.
T o ta l en erg y of b in d in g of a h eavy a tom . E. A.
Mi l n e (Proc. Camb. Phil. Soc., 1 9 2 7 , 2 3 , 7 9 4 — 7 9 9 ;
cf. Thomas, this vol., 2 0 0 ) .—Theoretical. Thomas’
differential equation for the average field inside a heavy atom is analogous to Emden’s equation for the polytropic equilibrium of a star. Using this analogy, the total electrostatic energy, and hence the total energy of binding, of an atom built on Thomas’
model is calculated. The total energy is found to be proportional to N vS, where N is the atomic number.
W. E . Do w n e y.
T o ta l io n isa tio n due to th e ab so rp tion in air of slo w cathod e ra y s. J. F. Le h m a n n and T. IL
Os g o o d (Proc. Roy. Soc., 1927, A , 115, 609—624).
-—Experiments were made to measure the average ionisation produced by the absorption in air of an electron with definite initial energy. A stream of electrons obtained from a tungsten filament charged to a definite potential was passed through an ionis
ation chamber, the initial energy of the electrons ranging from 200 to 1000 electron-volts. The ratio of ionisation current to electron current gave the average number of ions produced by the absorption of an electron. The average energy used up in the formation of a pair of ions is determined by dividing the initial energy of the electrons by the number of positive ions per electron for complete absorption.
The average ionisation per electron for complete absorption was found to be proportional to the initial energy of the electrons, and the average energy ex
pended in the formation of a pair of ions is 4 5 electron- volts in air. L . L . Bi r c u m s h a w.
A b so rp tio n of slo w cathod e ra y s in v a rio u s g a se s. J. F. Le h m a n n (Proc. Roy. Soc., 1927, A , 115, 624—639; cf. preceding abstract).— The total ionisation due to the absorption of slow cathode rays has been measured in helium, argon, hydrogen, nitrogen, and carbon dioxide. The average ionisation per electron, for complete absorption, was found to be proportional to the initial energy of the cathode ray. The rate of absorption of electronic energy required to correlate the present lfieasurements of the total ionisation and the measurements of the ionisation per unit path by Compton and Van Voorhis (A., 1926, 1074) and by Kossel (Ann. Physik, 1912, [iv], 37, 393) has been computed. Concordant results were obtained by estimating the range of the cathode rays in air from the rate of absorption of electronic energy, and from the pressure necessary to absorb the rays within the length of the ionisation chamber.
L . L . Bir c t t m s h a w.
Io n isatio n efficiency of u ltra -v io let lig h t in cæ siu m vapour. E. M. Li t t l e (Physical Rev., 1927, [ii], 30, 109—118).—The efficiency of ionisation (Einstein’s probability of absorption coefficient) in
caesium vapour at 166° increases from 0-17 x 10-10 ion per atom per erg at 3345 A. to 3-4 x 10"10 at 3135 A.
(± 5 % relative, 25% absolute). The theoretical threshold is at 3184 A. For shorter wave-lengths the value is minimal (1-2 x 10-10) at 2800 A. A surface of cassium-gold alloy is very active photo-electrically.
A. A. El d r i d g e.
M o b ilities of io n s in a ce ty len e-h y d ro g en m ix tu res. L . B . Lo e b and L . dtj Sa u l t (Proc. Nat.
Acad. Sci., 1927,13, 510—516; cf. A., 1926, 219, 449).
—Erikson (A., 1926, 989) found that neither the positive nor the negative ion in acetylene showed a change in mobility with age within time intervals greater than 0-002 sec., whilst at the same tim e the mobility was slightly greater for the negative than for the positive ion. The initial ions, positive and negative, were regarded as unimolecular. Carefully purified acetylene shows mobilities of 0-787 and 0-844 cm./sec. per volt/cm., for positive and negative ions respectively (0-708 and 0-769 on the accepted scale and 0-846 and 0-906 on the true absolute scale).
Wahlin (A., 1922, ii, 608) found the value 1-15 for the negative ion on the absolute scale. I t is con
sidered probable that the positive and negative ions in acetylene, once formed, have the same mobility of 0-846 on the absolute scale. The same is probably true for hydrogen. Cases in which the negative ion shows a higher mobility are explained b y the existence of free electrons as carriers in the early part of the life of the ion. Within experimental error, the results for acetylene-hydrogen mixtures agree with the law of mixtures for non-reacting gases. There is no evidence for a very rapid ageing of ions in acetylene, nor for clustering effects.
R. A. Mo r t o n.
N e w m a ss-sp e c tr o g r a p h and th e w h o le num ber ru le. F. W. A s t o n (Proc. Roy. Soc., 1927, A, 115, 487— 515).—The construction of the latest form of mass spectrograph is described, and details are given relating to the discharge tube, the slit system, the electric field, the magnetic field, the camera, and the vacuum technique. The photographed spectrum is nearly 16 cm. long and includes more than one octave of mass, the dispersion scale varying, for a change of mass of 1%, from 1-5 mm. at the most deflected end to 3-0 mm. at the least deflected end.
Three methods of measuring the mass ratios are described, including the method of coincidences, which consists in photographing in virtual coincidence the lines due to an unknown mass x and a known mass a by means of the application of suitable potentials the ratio of which differs by about 0-5%
from the expected ratio x : a (the magnetic field being kept constant). The intervals between the lines obtained in this way are measured with a Poynting’s tilting plate micrometer, and converted into intervals of mass by multiplying by the dispersion constants calculated for the mid-point of each interval. The unit of mass chosen is the neutral oxygen atom 0 1(S, and the masses measured in the mass-spectrograph are corrected for the mass of the electron. Details are given of recent work on hydrogen, helium, boron, carbon, nitrogen, fluorine, neon, phosphorus, sulphur, chlorine, argon, arsenic, bromine, krypton, tin, iodine, xenon, tungsten, and mercury, and measurements of
the masses (correct to 1 or 2 parts in 10,000) of 51 types of atom contained in the above elements have been made and are tabulated on the oxygen scale.
The isotopic constitution of mercury has been settled, new isotopes have been discovered in tin and sulphur, and the two doubtful isotopes of xenon confirmed.
The relations between tin and xenon previously announced have been found to be incorrect. Values for Li° and Li7 are obtained by a re-calculation of Costa’s results. A discussion is given of the “ packing fraction,” i.e., the divergence of the atom from the whole number rule divided by its atomic mass, which is a measure of the gain or loss of mass per proton when the nuclear packing is changed from that of oxygen to that of the atom in question. Theoretically, this is regarded as being due to the fact that the protons and electrons may be so closely packed that their electromagnetic fields interfere, and a fraction of the combined mass is destroyed, whereas outside the nucleus, the distances between the charges are too great for this to occur. If the packing fractions of the atoms, expressed in parts per 104, are plotted against their mass numbers, it is found that, with the exception of light atoms of even atomic number, all lie roughly on a single curve which descends from hydrogen 77-8 to a minimum of —9 in the region of bromine. It then ascends again and recrosses the zero line in the region of mercury. The packing fractions of the light atoms of even atomic number lie well below this curve and approximate to a branch rising less steeply to helium 5-4.
L. L. Bi r c u m s h a w.
R e v isio n of th e at. w t. of y ttr iu m . A n a ly sis of yttriu m ch lorid e. II. 0 . Ho n i g s c h m i d and A.
v o n We l s b a c h (Z. anorg. Chem., 1927, 165, 284—
288).—Yttrium chloride containing no spectroscopic
ally detectable quantity of other rare-earth metals has been converted into silver chloride, giving as the most probable value of the at. wt. of yttrium the value 88-925 (±0-002). H. F. Gi l l b e.
R ev isio n of th e at. w t. of d y sp r o siu m . A n a ly sis of d y sp r o siu m ch lorid e. O. Ho n i g s c h m i d and A. v o n We l s b a c h (Z. anorg. Chem., 1927,165, 289—
296).—Dysprosium sulphate, containing only about 0-1% of holmium, has been converted into the chloride, and analysed by conversion into silver chloride. Taking the at. wt. of silver as 107-88 and that of chlorine as 35-457, the most probable figure for the at. wt. of dysprosium is 162-46. H . F. Gi l l b e.
T racks of a -p articles th ro u g h silv e r b ro m id e in gelatin . L. My s s o v s k i and P. Ts c h i s h o v (Z.
Physik, 1927,44, 408— 420).—B y developing specially prepared plates of film thickness greater than 50 ¡x after they have been exposed to a-particles, records have been obtained of the tracks of these particles in the gelatin film. The method can be adapted to a continuous registration of the emission of a-particles from a source by means of a moving film.
R . W . Lu n t.
E lectrical m e th o d of counting- a- and H -p ar- ticles. H. Gr e i n a c h e r (Z. Physik, 1927, 44, 319—
325).—The use of an oscillagraph is described to give continuous photograph records of the fluctuations in the plate current in the last valve in the amplifier
which, in the author’s technique (A., 1926, 553), is employed for the detection and counting of a- and
of H-particles. R. W. Lu n t.
H ig h -sp ee d ß-rays fr o m rad io a ctiv e su b sta n c e s. D. K. Yo v a n o v i t c h and J. d’Es p i n e
(J. Phys. Radium, 1927, [vi], 8, 276—283; cf. A., 1925, ii, 732).—B y using the magnetic spectrum method with a direct deviation apparatus, high-speed ß-rays, or groups of rays, with the following values of H R (11 the radius of the path of a ray in a magnetic field of strength H) have been detected : mesothorium-2 28,000, 21,000, 16,700, 10,000, and 6800; thorium-J?+C' 18,000, 11,000, 6800, and 5480;
radium-^+C' 27,000— 15,000,10,700, and 9960 gauss- cm. The energy of some of these rays is of the same order as that of a-particles. R. Cu t h i l l.
A b so rp tio n of ß -p articles b y m a tter. G. Fo u r n i e r (Ann. Physique, 1927, [x], 8, 207—277).—An extended account of earlier work (cf. A., 1925, ii, 622; 1926, 880). R. A. Mo r t o n.
P o la risa tio n of a to m ic n u c le i and it s rela tio n to th e o rig in of y -ra y s. W. Ku h n (Z. Physik, 1927, 44, 32—35).—From a consideration of the order of magnitude of the electric moments of atoms, and of the frequency of y-rays it is concluded that the latter are associated with H- or He-particles, and not with electrons, in the nucleus. R. W. Lu n t.
T ra n sm u ta tio n of m e rcu ry in to g o ld . A. Pi u t t i
and E. Bo g g i o-Le r a (Rend. Accad. Sei. Fis. Mat.
Napoli, 1925, [iii], 31, 194— 198).— See A., 1926, 699.
In ter stella r ca lciu m . O. St r u v e (Astrophys.
J., 1927, 65, 163— 199).
T h eo ry of th e iso to p e effect in lin e sp ectra.
G. Joos (Ann. Physik, 1927, [iv], 83, 1054— 1064).—
The effect of nuclear mass on term values for higher atoms has been calculated on the basis of the scheme : nucleus, core, electrons. For deep orbits, the mass effect may be several times that valid for hydrogen
like systems, inasmuch as the dimensions of the core are little influenced, whereas for outer orbits the mass effect can be only a little greater or a little less than the hydrogen effect. R. A. Mo r t o n.
F ree p ath an d q u a n tisin g of m o le c u la r tr a n s
la tio n s. W. He i t l e r (Z. Physik, 1927, 44, 161—
169).—B y applying Schrödinger’s wave mechanics to the free electrons in a solid grating the characteristics of molecular spectra have been derived. The wave
length variation of the energy density of the radiation is shown to be equivalent to black-body radiation on which is superposed a weak fluctuation periodic with respect to wave-length. R. W. Lu n t.
Q uan tu m m e ch a n ics of lin e a r o sc illa to r s.
E. H. Ke n n a r d (Z. Physik, 1927, 44, 326— 352).—
The dynamics of an electron moving in a uniform magnetic or electric field have been analysed by quantum mechanics by assuming that the wave packets of Schrödinger m ay be identified with the discontinuous probabilities of classical quantum
theory. R. W. Lu n t.
Q uan tu m m e ch a n ics of d eg en era ted g a s e s . P. Jo r d a n (Z. Physik, 1927, 44, 473— 480).—
Mathematical. R. W. Lu n t.
916 BRITISH CHEMICAL ABSTRACTS.— A.
N e w d erivation of q u an tu m m ech a n ics. II.
P. J o r d a n (Z. Physik, 1927, 44, 1—25).—Mathem
atical. R. W. Lunt.
E lectron as a v ec to r w ave. C. G. Da r w i n (Proc.
Roy. Soc., 1927, A, 116, 227—253).—Mathematical.
E n e rg y ex ch a n g e a cco rd in g to th e w a v e m ech a n ics. E. Sc h r o d i n g e r (Ann. Physik, 1927, [iv], 83, 956—968).—Mathematical.
C h aracteristic v a lu es in th e lim itin g valu e p ro b lem of w a v e m e ch a n ics. K . Be c i i e r t (Ann.
Physik, 1927, [iv], 83, 905—912).
P h o to g ra p h ic m e th o d of sp ectro -p h o to m etry in th e red and infra-red . A. L. Sc h o e n (Brit. J.
Phot., 1927, 74, 475— 477).—See this vol., 394.
H yd rogen band sp ectru m : n ew b and s y s te m s in th e v io let. 0 . W. Ri c h a r d s o n (Proc. Roy. Soc., 1927, A, 115, 528—548).—A system of hands is de
scribed which includes much of the strength of the secondary hydrogen spectrum when this is excited by a sharply limited electron stream on the H 2 molecule. A provisional arrangement of the bands is suggested. There are two band systems (A and B), the first very strongly developed. The nucleus of the first band is at 21573-81. Only the Q branches of the bands are given, although there are indications that P and B branches exist also. The Q branch of the 1— >-0 band is the series 20Q{m) of Richardson and Tanaka (A., 1925, ii, 909). All the bands are degraded towards the violet, and each line is accom
panied by a fainter component on the long-wave side of it. The final states of the present bands appear to be the same as the initial states of the Lyman bands in the far ultra-violet. The lines with their properties and the initial and final vibration term differences are tabulated for both the A and the B bands. L. L. Bi r c u m s h a w.
S tru ctu re of certa in b a n d s in th e v is ib le s p e c tr u m of b oron m o n o x id e . F. A. Je n k i n s (Proc.
Nat. Acad. Sci., 1927, 13, 496—503).—The bright light emitted by boron trichloride in active nitrogen is due to boron monoxide. The spectrum consists of three electronic systems : a-bands extending from the red to the near ultra-violet and showing quadruple heads shaded towards the red, p-bands in the ultra
violet with single heads also shaded towards the red, and a combination system. The a-bands have now been photographed under high dispersion and their structure has been analysed. In each complete band there are two origins with four series proceeding from each. The interpretation follows the theoretical lines laid down by Mulliken (A., 1926, 452, 1079) and Hund (A., 1926, 657). Band systems for two boron isotopes have been established, and the moment of inertia for the vibrationless molecule has been com
puted for B110 and B 10O. As expected, the latter is much the smaller value, but the nuclear separation is identical for the two isotopic molecules. The structure of the a-bands is very similar to that of the CO+ comet-tail bands. The analogy also extends to the ¡3- and combination bands which resemble the negative Deslandres group of carbon and the B aldet- Johnson combination bands. R. A. Mo r t o n.
S p e ctr u m of carbon d iox id e. G. W. F ox , O. S.
Du f f e n d a c k, and E. F. Ba r k e r (Proc. Nat. Acad.
Sci., 1927, 13, 302—307).—The wave-lengths and intensities of most of the band edges in the absorption spectrum of carbon dioxide (which extends from 2800 to 5000 A.) are recorded. The continuous flow method (A., 1925, ii, 1017) was employed. Several strong band groups occur in which two or more band systems overlap. During the electrical discharge through carbon monoxide the reaction 2CO — >■
C02+ C occurs to some extent. S. K. Tw e e d y.
E lectro n ic s ta te s and b and sp ectru m stru ctu re in d ia to m ic m o le c u le s. V. B a n d s of th e v io let
C N (2S — > 2S) ty p e. R. S. Mu l l i k e n (Physical Rev., 1927, [ii], 30, 138— 149).—Theoretical intensity formulae applicable to bands of the violet CN(2&— t-28) type are obtained, and two Q branches are predicted.
Predicted intensity relations appear to be confirmed in the CaH, N 2+, and violet CN bands. The nature of the energy differences between the 2S terms corre
sponding with parallel and anti-parallel orientations of the electron spin vector is considered. I t is sug
gested that the 2;S' state in the B bands of CaH is of an unusual type. A. A. El d r i d g e.
E lectr ica l p ro p erties an d n a tu re of active n itro g en . P. A. Co n s t a n t i n i d e s (Physical Rev., 1927, [ii], 30, 95— 108).—The electrical behaviour of glowing active nitrogen indicates that the conduc
tivity between electrodes in the gas is not due to ions drawn from the discharge chamber, but to high- velocity electrons emitted from the electrode surfaces, either photo-electrically or by direct action of the active nitrogen on the metal. The glow is unaffected by helium, but is extinguished by nitrogen, hydrogen, and oxygen in order of increasing effect. Active nitrogen does not ionise hydrogen or mercury vapour, but appears to ionise iodine vapour. I t is therefore considered that active nitrogen is molecular nitrogen in a metastable state with energy between 9-4 and 10-4 volts. A. A. El d r i d g e.
|3-Bands of n itr ic ox id e. I. M easu rem en ts an d q u a n tu m a n a ly sis. . F. A. Je n k i n s, H. A.
Ba r t o n, and R. S. Mu l l i k e n (Physical Rev., 1927, [ii], 30, 150— 174).— Each complete band in the (3-system of nitric oxide (2300—5300 A.) consists of two sub-bands with P, B, and weak Q branches.
The frequencies of the band lines are tabulated, as also are the combination differences in the (0, 10), (0, 11), and (1, 11) bands, mean values of AzF{j) for various vibrational states, empirical coefficients in the rotational energy function, and the frequencies of band origins. The moment of inertia, I Q, and the internuclear distance, r0, for the vibrationless mole
cules axe evaluated a s: /„'= (24-80 ± 0 -0 2 )X 10-40 g.cm.2, 70" = (1 6 -3 0 ± 0 -0 2 )x l0 -40 g.cm.2, r'0= l- 4 1 8 x lO-8 cm., r0" = 1-150 X 10’8 cm., 7p" and r0" applying to the normal state of nitric oxide. Equations are given representing the frequencies of all observed lines, and the vibration frequencies for infinitesimal amplitudes are determined. All constants derived for the final state of the (3-bands apply equally well to that of the y-bands. The ultra-violet 0 2+ bands and certain SiN bands, the structure of which re*
