Ris s e (Z. physikal. Chem., 1929, 140, 133—157).—
The conditions governing the X -ray photolysis of aqueous hydrogen peroxide solutions have been studied over the concentration range 0-001—0-2531. At very low concentrations the quantity decomposed bears a linear relationship to the product It, where I is the intensity of the incident rays and t the time of expo
sure ; the decomposition velocity is practically inde
pendent of the concentration, whilst a t the higher concentrations, and down to about 0-05i¥, the process conforms tolerably well to the law for unimolecular reactions. Since the observed values do not satisfy the equation for second- or third-order reactions a complex process is postulated. Investigation of the action of X-rays on conductivity water shows th at dissolved oxygen is converted quantitatively into hydrogen peroxide and th a t even in absence of dis
solved oxygen the conductivity and acidity increase.
Irradiation of conductivity water by a quartz-m ercury lamp results in a greater increase of acidity, but no hydrogen peroxide is produced unless a photocatalyst such as zinc oxide is present. Activation of the oxygen is thus a necessary condition for the production of hydrogen peroxide from water and oxygen. During the decomposition of hydrogen peroxide by X-rays an inflammable gas is produced in quantity equal to about 1-5—2% of the volume of oxygen liberated.
The tem perature coefficient of the reaction in about M /600-solution is unity a t temperatures from 2° to 50°. Strong acids and alkalis retard th e decomposi
tion. From energy considerations it is demonstrated th a t the energy necessary for the complete decom
position of one molecule of hydrogen peroxide, which in M /600-solution is 70 kg.-cal., decreases with increase of the hydrogen peroxide concentration.
H. F. Gil l b e. A ction of lig h t and A-rays on am m onium thiocyanate. C. G. P a t t e n and H. D. S m ith (Trans. Roy. Soc. Canada, 1928, [hi], 22, I II , 221—
224).—When a concentrated aqueous solution of ammonium thiocyanate is exposed to sunlight for 1 min. it turns bright red, but the colour disappears in the dark after 2 min. This is not due either to the formation of sub-microscopic particles of sulphur, or to the dissociation of the salt into ammonia and thiocyanic acid, as has been supposed, but- to the fact th a t minute traces of iron in the salt are oxidised by a photo-reaction and then form the red ferric thiocyanate, the process being reversed in the dark.
The wave-lengths effective in this reaction extend from the middle of the visible spectrum well into the ultra-violet. X-Rays are equally effective as sun
light. The importance of this photo-reaction with iron in the explanation of the coloration and change in optical transparency produced in m any glasses by X-rays and intense sources of ultra-violet light is
being investigated. A. J . M ee.
408 B R ITISH CHEMICAL ABSTRACTS.— A.
Action of X-rays on ferrous sulphate solutions.
H. F ric k e and S. M orse (Phil. Mag., 1929, [vii], 7, 129—141).—The action of different X-ray doses on 0-01—4 X 10_5i/-solutions of ferrous sulphate in 0-SiV- sulphuric acid saturated with a h has been inves
tigated. W ith 0-00878Ji-, 0-000337M-, and 0-001Jf- solutions the rate of decomposition is linear up to the same X -ray dosage. For increased dosages the decomposition is still linear, but the rate is halved.
W ith a 0-0000406M -solution the rate of decomposi
tion has a linear relationship to the X -ray dosage until decomposition is practically complete. W ith increased doses th e concentration of ferrous sulphate is gradually restored to an equilibrium value about 50% of the initial one. In the first cases the change in the rate of decomposition is shown to take place a t the point where all the dissolved oxygen in the solutions has been used up. I t is concluded th a t in the later stages of the decomposition the transform ation of the ferrous ions is a secondary effect due to activated water molecules produced by secondary X -ray electrons. The apparent reversal of the reac
tion in the last case is attributed to the presence in the solution of a reducing substance (perhaps hydrogen peroxide) which would interfere with the analysis, which was carried out by an oxidation-reduction potential method. A. E. M i t c h e l l .
Production of colour in g la ss and in g e m s by X-rays and radium rays. M. C. R e in iia rd and B. F. Sc h r e in e r.—See B., 1929, 208.
Lattice energies and photochem ical decom position of the silver halides. S. E. S h e p p a r d and W. V a n s e lo w (J. Physical Chem., 1929, 33, 250—273).—Theoretical. The energy changes accom
panying the decomposition of the silver halides are discussed in relation to the lattice energies of the crystals concerned. The lattice energies of silver chloride, bromide, and iodide are first evaluated using the thermochemical cycle of Born (A., 1920, ii, 156) after a consideration from th e results of previous investigators of the best values for the terms to be taken. By this method the lattice energies have the values 212, 205, and 201-5 kg.-cal., respectively, as compared with the values 184,178, and 150 calculated from the electrostatic theory. I t follows th a t the quantum required to overcome electron affinity is greater th an th a t actually found by experiment to be necessary. The relation of lattice energy to photo
chemical change is discussed in the hght of these results and of other evidence, and it appears th at lattice loosening and electron liberation and transfer are closely connected with any photochemical change in solids. A discussion of lattice disorientation and of ionic deformation in the light of the work of von Hevesy and Fajans, respectively, leads to the con
clusion th a t both photochemical and photo-electric effects take place primarily in such disoriented parts of the lattice th a t the initial work can be supphed by the quanta available, a view which receives sup
port from the fact th a t photochemical decomposition commences locally on the surface of crystals. The preliminary overcoming of lattice energy which is necessary before absorbed radiation can loosen an electron is analogous to energy of activation in
chemical reactions, and it is concluded th a t the photochemical decomposition of the silver halides can be regarded as a typical case of heterogeneous catalysis a t an interface. Internal disorientation and photo
conductance, photo-electric effects, and orientation at interfaces are also discussed. L . S. Th e o b a l d.
Interm ediate regression s. L u p p o -C ra m e r (Z.
wiss. Phot., 1929, 26, 295—299).—If a negative which has been treated with a sodium nitrite solution is exposed under the Eder-H echt scale under conditions which would cause solarisation in an untreated plate, solarisation is hindered except under the red strip.
Since the ordinary Herschel effect cannot be obtained with this red filter, it is suggested th a t the red rays exert a protective influence on the silver halide, pre
venting blackening when the silver nuclei are nascent, as in the present experiments, but not when, owing to previous exposure, they have become larger and
less reactive. R. C u t h i l l .
L im iting short w ave-length for the Herschel effect. E. M a u z (Z. wiss. Phot., 1929, 26, 289—
294).—On exposure to yellowish-orange light of
“ Satrox ” paper which has previously been blackened by exposure to white light, the blackening a t first diminishes, i.e., the Herschel effect appears, but later increases again. In explanation it is suggested th at one p a rt of the orange light causes bleaching, and the other p a rt blackening, and th a t when the time of exposure is increased beyond a certain point the blackening effect predominates. By photographing a spectrum on paper previously exposed to white light, it is found th a t light of wave-length shorter than about 600 m[x, will not cause the Herschel effect.
R. Cu t h il l. P hoto-decom position of ethyl iodide. T. I r e -d a l e (J. Physical Chem., 1929, 33, 290—295).—
Measurements of the photo-decomposition of ethyl iodide a t the ordinary tem perature by light of the region 365 jxu from a quartz-m ercury vapour lamp indicate th a t this is a simple process (cf. Job and Emschwiller, A., 1924, i, 929) in which one quantum effects the detachment of an atom of iodine from one molecule of the iodide. Preliminary experiments indicate th at, contrary to Stobbc and Schmitt (A., 1921, ii, 76), oxygen is not necessary for the decom
position. L . S. T h e o b a ld . P hotosynthesis of naturally occurring co m pounds. IV. Tem perature coefficient of the photosynthesis of carbohydrates from carbonic acid. E. C. C. B a l y and N. R. H o o d (Proc. Roy.
Soc., 1929, A, 122, 393—398; cf. A., 1927, 1040, 1041).—Nickel carbonate, free from every trace of adsorbed salts, may be prepared by the electrolysis of pure conductivity water, saturated with carbon dioxide, with nickel electrodes. The carbonate is dried a t 100°, heated a t 140° for 30 min., passed through a 100-mesh sieve, and activated by exposure to light. Nickel carbonate thus prepared gives very constant yields of carbohydrates if the temperature, hght intensity, and relation between volume of water and weight of powder are kept constant. If the yield of carbohydrates (weight of photosynthesised organic m atter soluble in absolute methyl alcohol) obtained with 50 g. of the carbonate suspended in
GENERAL, PH Y SICA L, AND INORGANIC CHEMISTRY. 409 1500 c.c. of water is plotted against th e temperature,
the relation is found to be a linear one between 5°
and 31° (maximum yield, 0-0783 g.), after which there is a rapid decrease in yield. The values of the temperature coefficient for 10° are in good agreement with those found by W arburg with the unicellular alga Chlorella under constant illumination (Biochem.
Z., 1919,1 0 0 ,258). The close analogy shown between the photosynthetic process in vitro and in vivo is discussed, with special reference to the work of Matthaei on the assimilation of carbon dioxide at various temperatures (Phil. Trans., 1905, B, 197, 47), and to the fact th a t the process, both in the living leaf and in the laboratory, has an upper and a lower temperature limit. The results recorded support the view previously expressed (loc. cit.), th a t the complete activation of the carbonic acid takes place in two stages, i.e., partial activation by adsorption on the surface of the catalyst and a farther activation by the action of visible light on the adsorbed layer.
L. L. Bir c u m sh a w. Photochem ical decom position of benzalde- hyde. A. d e H e m p tin n e (Ann. Soc. Sci. Bruxelles, 1928, 48, B , 98—100).—I t is concluded th a t the photolysis of benzaldehyde by light of wave-lengths less than 2600 Â., which was previously observed (A., 1928, 720), takes place as follows : CcH 5-CHO=
C8H 5+ H - f CO, the hydrogen then reacting with the phenyl group to form benzene. The energy necessary for this decomposition is calculated to be 115,780 g.-cal„ corresponding with light of wave-length 2461 Â. This is the wave-length a t which the total absorption band of the benzaldehyde spectrum begins.
For benzaldehyde there is a complete parallelism between the appearance of total absorption and the possibility of photochemical decomposition.
O. J . Wa l k e r. Photochem ical decom position of benzaldehyde vapour. A. d e H e m p tin n e (J. Phys. Radium, 1928, [vi], 9, 357—364; cf. preceding abstract).—
The decomposition by ultra-violet light of benzalde
hyde vapour a t 0-2 mm. has been investigated. Only those wave-lengths corresponding with the “ total absorption ” portions of the benzaldehyde spectrum are effective in the photochemical decomposition.
With rise of tem perature the intensities of the bands gradually decrease until a t 200° a continuous spectrum results, which in tu rn disappears a t 400°. Below this tem perature the photolysis is reversible. Be
tween 400° and 500° benzaldehyde begins to decom
pose thermally and irreversibly. The decrease in the light energy necessary for decomposition a t the higher temperatures is of the same order of magnitude as the increase in the vibration energy of the benz- aldehyde molecule, as calculated from the variation of the specific heat with the tem perature. The theory of absorption spectra and photochemical decomposition is discussed. O. J . W a l k e r .
Relations betw een the photochem ical reactivity and the fluorescence of organic compounds.
Qualitative fundam ental law. G. K ô g e l (Z.
wiss. Phot., 1929, 26, 311—319).—Theoretical. From the fact th a t by opening the rings of fluorescent closed-chain compounds and introducing unsaturated
groups a t the point of fission, if such groups are not already present there, compounds which are very sensitive to light are obtained, it is concluded th a t fluorescence is a criterion of photochemical activity.
If, however, owing to structural or physical conditions reaction is not possible, the fluorescence represents only potential activity. The principal groups giving rise to photochemical sensitivity a r e : *CH;CH-,
•CH.'N*, > C :0 , -NOg, 'NClrN, and IN:N. Substituents for the hydrogen atoms hi the benzene ring will enhance the fluorescence or promote chemical action according as they oppose or facilitate, respectively, the opening of the ring. The groups Me and OMe and the halogens increase the reactivity of the sensitive groups, whilst the nitro-group has the opposite effect. R. Cu t iiil l.
Physico-chem ical investigations of irradiated proteins. V. Changes in serum -album in pro
duced by radium rays and their relation to coagulation by heat and light. A. F e r n a t j and M. S p i e g e l - A d o l f (Biochem. Z., 1929, 204, 14—27).
—Freshly elcctrodialysed serum-albumin kept under toluene loses its power of coagulation by exposure to radium owing to the formation of traces of ammonia.
To prevent visible changes under radium irradiation, small amounts of acid or alkali are effective. Even when visible changes are prevented by hydrochloric acid there is almost complete denaturation. The period of coagulation is practically independent of the concentration of the serum-albumin. Coagulation is prevented by high concentrations of neutral salts.
Radium coagulates are not rendered soluble by the action of alkali. Hydrogen peroxide coagulates show properties similar to those produced by radium.
J . H. Bir k i n s h a w.
Reaction of m onatom ic hydrogen w ith hydro
carbons. K. F. B o n h o e f f e r and P. H a r te c k (Z.
physikal. Chem., 1928, 139, 64—74).—When hydro
carbon vapours, methane excepted, are allowed to m ix with a stream of monatomic hydrogen a greenish - blue light, resembling that of the imier cone of a Bunsen flame, is emitted. The products of reaction have been examined for the following substances : ethane, pentane, ethylene, acetylene, and benzene.
No change takes place in the case of methane, but the evidence indicates that this gas facilitates the recom
bination of monatomic hydrogen according to the equations : CH.l+ H = C H 3+ H 2, CH3+ H = C F L . Ethane gives small quantities of ethylene and acetyl
ene and some methane, but is mostly unchanged. Pent
ane gives the same products as ethane with propane in addition. Ethylene yields acetylene, but acetylene, although giving a strong light emission, gives only traces of ethane and ethylene and remains practically unchanged. In the case of benzene the ring is broken, and methane, together with some ethylene and acetylene, is formed. The results therefore show that monatomic hydrogen may hydrogenate and dehydro- genate hydrocarbons, and may rupture very stable
rings. R. W. Lunt.
Form ation of acid lithium alum inate. D.
Pr o c iv (J. Czechoslov. Chem. Comm., 1929, 1, 95—
103).—The solution obtained by the dissolution of aluminium amalgam in aqueous lithium hydroxide
410 B R IT ISH CHEMICAL ABSTRACTS.— A.
which exhibits “ supersaturation ” (cf. Allen and Rogers, A., 1900, ii, 727) has been investigated by conductance and cryoseopic methods and it is con
cluded th a t the aluminium in the solution exists mainly as the normal alumínate, Al(OH)4', before spontaneous precipitation. The solubility of acid lithium alumínate, Li[Al2(0H )7],2H20 or
Li2Al40 7,l l H 20 , deduced from the conductance measurements is 1-2 x lO-4 and 3-3 X10~4 g.-equiv. per litre a t 25° and 80°, respectively. The separation of the acid lithium alumínate takes place according to the equation, 2A1(OH)4':5=í=A12(OH)7'x OH', the mass action constant of which is about I x l O 4. A method for the determination of lithium based on its precipitation as the acid alumínate in sodium or potassium hydroxide solutions is described.
A. I . Vo g e l. Com bination of alkali m etals w ith carbon. II.
K. Fr e d e n h a g e n and H . Su ck (Z. anorg. Chem., 1929, 178, 353—365).—The investigation previous^
described (A., 1927, 218) has been continued with improved apparatus. When heated a t 400° in potassium vapour a t a given pressure, both graphite and lampblack take up the same amount of metal, but with lampblack equilibrium is reached only after a considerable time. A curve constructed with the pressures of vapour as absciss* and the amounts of metal taken up as ordinates consists of two almost vertical portions separated by a short flatter p a rt;
with further increase in pressure, the second and longer steep section is ultim ately succeeded by a part which slopes much less. There is no evidence of the formation of K 2C2, and the most satisfactory explan
ation of the form of the curve seems to be th a t adsorp
tion occurs in two stages. Neither sodium nor potassium reacts with diamond a t 500°.
R . Cu t h il l. D isplacem ent of copper from neutral and acidic copper sulphate solutions by hydrogen under pressure. V. I p a t i e v and V. I p a t i e v , jun.
(Ber., 1929, 62, [JB], 386—390).—The experiments are performed in an Ipatiev high-pressure autoclave containing the solution in a glass tube. Under all conditions cuprous and cupric salt and metallic copper are present a t the close of the experiment. Copper cannot be displaced without the simultaneous presence of cuprous and cupric ions in the solution, the latter frequently in very small amount. Precipitation of copper is never quantitative, a portion of the metal remaining ionised in solution no m atter how long the experiment is continued. I t appears th a t the following reactions proceed simultaneously: 2CuS04+
H o= C u 2S 0 4+ H 2S 0 4; Cu2S04+ H 2= 2 C u + H 2S04;
CuS04+ C u = C u 2S 04. W ith increasing acidity of the solution, the conditions become more favourable for a high concentration of cuprous ions; in some cases, this increase is effected a t the expense of the precipitated copper. A t a constant pressure of hydrogen, the influence of added acid becomes less marked with increasing concentration of the copper
sulphate solution. H. Wr e n.
Reaction of cupric sa lts w ith thiosulphate.
J . H a n u s and V. H o v o r k a (J. Czechoslov. Chem.
Comm., 1929, 1, 65—S2).—A re-investigation of the
reaction between cupric salts and sodium thiosulphate in aqueous solution over a wide variety of conditions has been made. The resultant precipitate was analysed as follows : sulphur, by extraction with nitrobenzene a t 100°; cuprous sulphide, by tre a t
m ent with silver sulphate solution which converts the cuprous sidphide into cupric sulphate, silver sulphate, and an equivalent quantity of silver (cf.
Posnjak, A., 1915, ii, 24), the last-named being removed by dissolution in 6% fem e nitrate solution a t about 80° and the silver determined by Volhard’s method. The precipitate consisted of a m ixture of cuprous and cupric sulphides and free sulphur in varying proportions, the composition depending on the duration of boiling, the amount of thiosulphate, and the acidity of the solution. The maximum am ount of cuprous sulphide in the precipitate was obtained from solutions in which the ratio was 1 g.- at. of copper to 2-5—3 mols. of thiosulphate. Further increase of the thiosulphate content resulted hi a decrease of the amount of cuprous sulphide until with a very large excess (1 : 15—30) the precipitate consisted largely of cupric sulphide and free sulphur.
The composition of the precipitate formed in acid solutions according to the analytical methods of Carnot (A., 1886, ii, 580) and Girard (Aim. Cliim.
anal., 1899, 4, 382) (copper: thiosulphate about 1 : 4 —5) was 8% Cu2S + 92% CuS.
A. I. Vo g e l. Constitution of silver subfluoride. C. d e l F r e s n o (Anal. F is. Q uim ., 1928, 26, 407—416).—
See A., 1928, 694.
Action of w ater on calcium alum inates. L. S.
W e l l s .—See B., 1929, 173.
Carbon sulphidoselenide. H . V. A. B r is c o e , J. B . P e e l , and P . L. R o b in s o n (J.C.S., 1929, 56—
60).—Carbon sulphidoselenide (cf. Stock and Will- froth, A., 1914, ii, 200), a yellow oil, b. p. 83-90—
83'95°/749-2 mm., has been prepared by treatingferrous selenide with carbon disulphide vapour a t 650°, and repeatedly fractionating the product. The mol. wt., determined by vapour density and by cryoscopic measurement, is normal. Thesurfacetension y =40-44 dynes/cm.2 a t 20°, lienee the molecular parachor is 156-4. If the constitution S-C-Se be assumed for the sulphidoselenide, the atomic parachor of selenium is 58-7 (cf. Briscoe and Peel, A., 1928, 1021).
Carbon sulphidoselenide is reduced by zinc and hydrochloric acid to hydrogen sulphide and hydrogen selenide. I t reacts with ammonia, b u t the products are ill-defined. W ith phenylhydrazine in alcoholic solution it yields the compound (NHPh-NH2)2,CSSe, m. p. 98°, which is unstable and decomposes when kept; under similar conditions aniline yields a com
pound, (NHPh)4CSSe, m. p. 164°, which is somewhat more stable in air. C. W. Sh o p p e e.
[Silicic acids.] H. S t a u d i n g e r (Ber., 1929, 62, [J5], 442).—The conception of the relationship between fibrous structure and molecular size, a ttri
buted by Dilthey and Holterhoff (this vol., 280) to Meyer, has been enunciated previously by the author.
H . Wr e n. Reactions betw een colloidal silica and lim e.
P. Jolib o is and L. Ch a sse v e n t (Compt. rend., 1929,
GENERA L, PH YSICA L, AND INORGANIC CHEMISTRY. 411
GENERA L, PH YSICA L, AND INORGANIC CHEMISTRY. 411