Ray examination indicates that a small particle size of the dry hydroxide gel is associated with the

more active catalysts. A minimum particle size at 22“ may be produced as the result of two opposing factors, viz., the tendency for the initial particle size to decrease with falling temperature of precipitation, and the tendency for the initially formed particles to grow while the hydroxide is drying at 110°.

S. K. T w e e d y . Copper catalysts prepared from precipitated hydroxide. II. C om parison of sod iu m hydroxide and am m onia as a p recip itatin g agent. P . K.

F r o l i c h , M. R. F e n sice, L. R. P e r r y , and N . L.

H u r d (J. Amer. Chcm. Soc., 1929, 51, 187—193).—

When sodium hydroxide is the precipitating agent (cf. preceding abstract) the catalysts are much more active, due to promoter action of occluded sodium salts. Below 313° the activity of such catalysts is independent of tim e; at 380° the catalytic power is immediately destroyed. Thus fused occluded sodium salts appear to cover the active patches of the cata­

lysts. Copper catalysts prepared by precipitating copper chloride or sulphate with sodium hydroxide

are practically inactive. The promoted catalysts favour the formation of methyl formate in the thermal decomposition of methyl alcohol rather than that of formaldehyde. The conclusions are confirmed by experiments with catalysts containing known amounts of sodium nitrate. The results may explain some of the discordant observations recorded in the literature.

S. K . T w e e d y . S y n th e sis of w ater w ith a silv er catalyst. II.

E nergy of activation and m ech a n ism . A. F.

B e n t o n and J. C. E l g i n (J. Amer. Chem. Soc., 1929, 51, 7— 18).—The synthesis of water in presence of a silver catalyst was investigated, the adsorption by the catalyst of oxygen and of water vapour (in presence of oxygen) being measured also. The oxygen adsorption is nearly independent of temperature and pressure (cf. A., 1927,118). Water vapour is adsorbed much more strongly by a silver surface covered with adsorbed oxygen than by a bare surface. The reaction rate is independent of the oxygen pressure, but pro­

portional to the hydrogen pressure and to the fraction of catalyst surface free from adsorbed water. The calculated energy of activation is 16,000 g.-cal. It is concluded that reaction occurs at every collision of hydrogen with “ dry ” adsorbed oxygen in which the energy available on collision exceeds the energy of activation. The results are probably not in disagree­

ment with Taylor’s theory of catalyst surfaces.

S. K. Tw e e d y. [Catalytic] sy n th esis of m ethane fro m carbon d ioxid e and hydrogen. M. R a n d a l l a n d F . W.

G e r a r d . — See B ., 1929, 82.

[Catalytic] sy n th esis of h igh er hydrocarbons fro m w ater-g as [at atm ospheric p ressu re]. II.

D. F. S m ith , C. O. H a w k , and D. A. R e y n o l d s . — See B „ 1929, 82.

Catalytic oxidation of naphthalene. T.

K u s a m a .—See B ., 1929, 88.

E ffect of inh ib itors on the acid d issolu tion of copper and copper alloys. H. O. F o r r e s t , J. K.

R o b e r t s , a n d B . E . R o e t h e l i . — See B ., 1929, 98.

T heory of ch em ical action in electrical discharge. S. C. L i n d (Science, 1928, 67, 565—

569).—An address to the American Electrochemical Society, April 26, 192S.

F orm ation of ozone in the electrical discharge at p ressu res b elow 3 m m . J. K. H u n t (J. Amer.

Chem. Soc., 1929, 51, 30—3S).—During the first half minute the quantity of ozone formed is approximately proportional to the input of electricity, but equilibrium is soon reached. The yield increases with increasing pressure, but at a decreasing rate; it is independent of the electrode material (small electrodes were used;

aluminium gives abnormally high results) and increases with increasing cathode area. The number of ion pairs and of ozone molecules produced are both of the same order of magnitude. The following mechan­

ism is suggested: 0 2= 0 ++ 0 - ; 0 + + 0 2= 0 3+ ; 0 - + 0 2= 0 3- ; < V + 0 3- = 2 0 3 or 0 3++ 0 - = 2 0 2 and 0 3~ -f 0 += 2 0 2. S. K. T w e e d y .

E lectrolytic preparation of h ydroxylam ine.

J. G. S t s c h e r b a k o v a n d D. M. L i b i n a (Z. E le k tro - c h e m ., 1929, 35, 70—S3).—D iffe re n t m e th o d s of

determination of the liydroxylamine produced by the electrolytic reduction of nitric acid in sulphuric acid solution using a mercury cathode yield distinctly different results, and it is concluded that, besides hydroxylamine, considerable quantities of a second reducing agent are formed by the electrolysis. This is proved to be a compound of hydroxylamineiso- monosulphonic acid with sulphuric acid,

(NH2,0 ,S03H)2,H2S 0 4. A low nitric acid concentra­

tion favours the formation of the wo-compound, which liberates iodine from potassium iodide, is oxidised to nitric acid by titration with permanganate in the cold, and is hydrolysed by heating to hydroxylamine. The combined sulphuric acid may be determined by titra­

tion with alkali, using phenolphthalein. An electro­

lyte containing the two compounds remains stable at the ordinary temperature for an indefinite period of time. An increase in the sulphuric and nitric acid concentrations up to certain limits (15— 16iV-sulphuric acid and iV-nitric acid) causes an increase in the current yield of hydroxylamine, whilst below 3— 4i\r- sulphuric acid a pronounced decrease takes place.

For nitric acid concentrations above N , considerable quantities of oxides of nitrogen are formed. The most favourable acid concentrations, current densities, and temperatures are given, with which a mean current yield of GO—70% of hydroxylamine is obtain­

able. Under certain conditions (e.g., the presence of foreign metals in the electrolyte, dissolved from the electrodes), the nitric acid is not reduced at the mercury cathode, but a hydrogen evolution of almost 100% takes place. At higher nitric acid concentra­

tions, oxides of nitrogen are formed. In these cir­

cumstances, the cathode is found to be covered with a thin, scarcely visible film, which acts as a diaphragm and prevents reduction. The presence of the film increases the current yield of the iso-compound. At the end of the electrolysis, the free nitric acid may conveniently be removed by electrolysing with a copper cathode, since by this means the nitric acid is reduced to ammonia, whilst the hydroxylamine and iso-compound are unaffected.

L. L. B ir c u m s h a w . Influence of current d en sity in th e electrolytic preparation of sod iu m perborate. F. G i o r d a n i and R. I n t o n t i (Rend. Accad. Sci. fis. mat. Napoli, 1928, [iii], 3 4 , 30—36).—The yields of sodium per­

borate, obtained by electrolysing solutions of borax and sodium carbonate under conditions in which the current passing through the electrolyte was 10, 5, and 2*5 amp./litre, respectively, have been deter­

mined. Assuming that the perborate is formed according to the schemes Na„C03— 2>-NaC03'+ N a', 2NaC03'+ 2 F — >Na2G,Ofl, Na“„C20 6+ N a B 0 2+ 2 H ,0 2N aH C O .,+N aB O H 20 2, Na2B40-+ 2 N a O H —^

4NaB02+ H 20 , it is shown that the effective instan­

taneous yield of perborate is given by p = 2 F (V /

^)t(Na.,C2O0)(NaBO2)/pj, where Pj is the current efficiency in the formation of sodium percarbonate, V the volume of the solution, and I the current

•intensity. F. G. T r y h o r n . Electrolytic p recip itation of m eta ls. K.

Arndt (Ber., 1929, 6 2 , [5], 80—84).—Study of the distribution of a metal on a cathodic surface frequently

gives wave-like curves with distinct maxima and minima. Interposition of a non-conducting screen of mica or celluloid, pierced with a fine hole in the centre, between cathode and anode in the electrolysis of Ottel’s solution (150 g. CuS04,5H20 , 50 g. B^SO^

and 50 g. of alcohol per litre) causes the metal to be deposited in concentric rings which are more or less sharply defined. All the crystals have approximately the same size (5 a). I t is considered that the current initially causes an approximately uniform distribution of crystal nuclei and that subsequently the particles in unfavourable positions pass into solution whilst metal is deposited at the favourable positions. Study has also been made of the deposition of copper on a silvered cathode without a shield with a current density so small that the individual crystals can be measured and counted, Ottel’s solution being used. Increased current density, cooling, or dilution increases the number of copper crystals, which is lessened by warm­

ing or decrease in current density. At the ordinary temperature with 8 milliamp. the size is about 1-5 ¡x, with 40 milliamp. about 0-5 [x. At 0° the size is also approximately 0-5 |x, whereas at 35° the few particles may attain 5 (i. From the warm bath crystals are obtained as much as 5 [x long. Addition of 0-1% of gelatin to the acid copper bath renders the copper particles so small that they cannot be distinguished under the microscope. A uniform copper deposit is also obtained from a copper bath containing potassium cyanide. H. W r e n .

T heory of electro-d ep osition of ch rom iu m fro m aqueous so lu tio n s of ch ro m ic acid. E.

Müller and P. Ekwall (Z. Elektrochem., 1929, 3 5 , 84— 89; cf. Schischkin and Gernet, A., 1928, 4S9).—

A microscopical examination has been made of the deposits obtained under various conditions when 30%

aqueous solutions of chromic acid are electrolysed, using smooth platinum electrodes. Photomicrographs are reproduced, showing the results with very carefully purified chromic acid, free from all traces of sulphate, with chromic acid 0-001, 0-01, 0-05, and 0-liV with respect to sulphuric acid, and chromic acid free from sulphate but containing tervalent chromium. The last-named solution was prepared by boiling chromic acid with hydrogen peroxide and contained about 0-13 g. of tervalent chromium to 1 g. of sexavalent chromium. The results confirm Midler’s previous view (cf. A., 1926, 913), that a non-conducting diaphragm of chromic chromate is formed at the cathode, which hinders access of chromium ions but is permeable to hydrogen ions. At potentials lower than —1-1 volt, deposition of metallic chromium begins to take place, the first layer of metal deposited forming an alloy with the platinum. In the presence of sulphate ions, the chromic chromate diaphragm is considered to be mechanically imperfect and may be removed by the gaseous hydrogen evolved. For this reason, the presence of sulphates promotes deposition of chromium in a bright coherent form.

Similar residts are obtained if sulphate-free chromic acid containing tervalent chromium is used. A study was made of the cataphoretic behaviour of solid chromic chromate in the colloidal state, prepared by adding excess of alcohol to a concentrated solution

276 B R IT IS H CHEM ICA L A BSTRACTS.— A.

of pure chromic acid, dissolving the brown gel, which formed after some time, in water, and dialysing the resulting solution. The chromic chromate migrates to the cathode, and is believed to be a basic compound with the composition Cr2(0H )4Cr04.

L. L. B ir c u m s h a w . E lectrolytic oxidation of m eth yl alcohol in alkaline solution. S. T a n a k a (Z. Elektrochem., 1929, 3 5 , 38—42).—An investigation has been made of the relations between anode potential and current density in the electrolytic oxidation of methyl alcohol mixed with an equal volume of SX-sodium hydroxide, using as anode material smooth and spongy platinum, palladium, and rhodium, smooth gold, and silver.

The current-potential curves for the smooth metals are all similar in form, but differ from those for the spongy metals, which resemble those obtained in the electrolytic oxidation of formaldehyde in alkaline solution (cf. Müller and Takegami, A., 192S, 1338).

A current rise is observed in the low potential region, followed by a sudden fall, after which a second current rise occurs in the high potential region. In no case was any evolution of gas observed on the first rise, and with the smooth metals, the current rise at low potentials was absent. With rising temperature, the first rise becomes steeper and leads to higher current densities. The anolyte was analysed for form­

aldehyde and formic acid. No aldehydo appears to be produced, and it is considered that the reaction occurring in the low potential region may be repre­

sented by CH30 ' + 0 H ' —4 faradavs=H-CO,,H+2H' or CH3Ö'-f 3 0 H '—4 faradays=H-C02H + 2 H 20 . A theory developed to explain the observed phenomena is based on the supposed adsorption of the alcohol anions on the electrode surface.

L . L . Bir c u m sh a w. R egularity of the p hysical and ch em ical action of A'-rays. R. G l o c k e r (Z. tech. Phys., 1928, 9 , 201—207 ; Chem. Zentr., 1928, ii, 1063).—The law of photochemical equivalence is not applicable to X-rays, since the number of electrons liberated as a secondary process far exceeds that of the electrons primarily liberated by the absorption of the radiation.

In photochemical reactions in solution, electrons liberated from all the molecules present, and not merely those of the solute, are active in the chemical

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

P h oto-expan sion of chlorine. W. H. M a r t i n , A. F. W. C o l e , and E. E. L e n t (J. Physical Chem., 1929, 3 3 , 14S— 153).—Contrary to the observation of Slienstone (J.C.S., 1897, 71, 471), purified and dried chlorine still shows expansion when exposed to light.

Chlorine fractionated by means of liquid air over purified phosphorus pentoxide showed practically no decrease in expansion, as compared with the undried chlorine, when insolated by the light from a carbon arc. Baking-out the expansion bulb at 425° under a pressure of less than 0-0001 mm. of mercury for 4 days before admission of the dried chlorine had no effect on the photo-expansion. The present experi­

ments together with those previously reported (A., 1926, 559) show that dried chlorine at 1 atm', and at lower pressures exhibits no abnormal scattering nor any fluorescence which can be detected visually or

p h o to g ra p h ic a lly . T h e a s su m p tio n t h a t d r y chlorine d o es n o t e x p a n d o n in so la tio n b u t r e -ra d ia te s adsorbed e n e rg y is u n w a rra n te d . L. S. T h e o b a l d .

P h otoch em ical union of h ydrogen and chlorine.

A . J. A l l m a n d and E . B e e s l e y (Nature, 1929,1 2 3 , 164).—The results of a study of the effect of the intensity of monochromatic light arc in agreement with those of (Mrs.) Chapman, Kornfeld and Steiner, and Marshall. The effect of wave-length (A.) on the quantum efficiency is as follows: 2600, 0-10; 3130, 0-49; 3650,0-53; 4050,1-00; 4360,0-67; 5460,0-22.

The sensitivity of the gas used corresponded with a yield of the order of 2 x 105 mols. of hydrogen chloride per quantum of blue light absorbed ; the mixture showed no induction period, but gavo a marked Draper effect during the first instants of insolation.

The relative temperature coefficients (between 19-7°

and 25°) of the quantum efficiency increase slowly with wave-length between 3130 and 4360 A. When acting simultaneously, two monochromatic beams gave a velocity equal to the sum of their separate effects. A. A. E l d r i d g e .

B udde effect in brom ine. E. M a t t h e w s (Trans.

Farada\' Soc., 1929, 2 5 , 41—43).—A slight expansion on illumination by a 100-c.p. lamp was recorded for mixtures of dried bromine vapour and air at temper­

atures between 20° and 95°; a smaller expansion was shown by dry bromine vapour in the absence of air, and a somewhat greater one in the case of a mixture of bromine vapour and air which had not been dried over phosphorus pentoxide. F. C. T r y i i o r n .

Further te st of th e radiation h ypothesis. L. S.

K a s s e l (J. Amor. Chem. Soc., 1929, 5 1 , 54—61).—

The decomposition rate of nitrogen pentoxide, even at very low pressure, is not increased by radiation of wave-length less than 5 ¡j.; not more than 3% of the total thermal reaction can be caused exclusively by radiation of wave-length less than 5 ¡j.. The region between 5 and 10 ¡x may be all-important if the radi­

ation theory is the true explanation (which is improb­

able) of the anomalous nitrogen pentoxide decom­

position. If the diameter for intrinsic energy transfer of the nitrogen pentoxide molecule is approximately independent of the energy, and if it is larger than the kinetic theory diameter (which would supply an explanation of the anomalous decomposition rate), then the thermal conductivity of the gas should be abnormally large. ' S. K . T w e e d y .

M echanism of the photochem ical d ecom ­ p o sition of nitrogen pentoxide. W. P. B a x t e r and R. C. D ic k i n s o n (J. Amer. Chem. Soc., 1929, 5 1 , 109—116).—From measurements of the relative rates of decomposition of nitrogen pentoxide at 0°

by radiations of wave-lengths 4350, 4050, and 3660 A., and comparison with the rates of decomposition of nitrogen dioxide, it is concluded that the mechanism of the pentoxide decomposition is essentially that suggested by Norrish (A., 1927, 119, 528).

S. K. T w e e d y . H erschel effect. L u p p o -C ra m e r (Z. wiss. Phot., 1928, 2 6 , 249—259).

S pectral distribution of th e inn er photo­

effect in th e silver halides. E. A. K i r i l l o v (Z.

wiss. Phot., 1928, 26, 235—248).—The photo-electric conductivity of granular layers of silver halides has been investigated. New maxima in the longer waves have been found. In the case of silver bromide, the conductivity was less in the presence of light.

W. E. D o w n e y . Photolysis of silv er b rom id e. E. M u t t e r (Z.

wiss. Phot., 1928, 26, 193—234).—The bromine liberated by the photolysis of silver bromide in the presence of water exists as ions. Nitric acid dissolves the photolytic silver in small degree, the degree of regression being a function of the time and of the concentration of the solution. As a result of second­

ary reactions, hydrogen ions and free oxygen also appear. This behaviour is explained by the hypo­

thesis that the hydroxyl ion behaves as an acceptor.

The nitrite ion behaves similarly. The quantum yield in the presence of the nitrite ion is approximately 1. For equivalent substances the yield is only about 0-1 owing to the strong regression. Thus, the same amount of silver causes a much stronger blacken­

ing in the presence of nitrite than in that of equivalent

substances. W. E. D o w n e y .

Photolysis of silv er h a lid es in th e lig h t of the quantum th eory and th e p hoto-electric effect.

H. K i e s e r (Z. wiss. Phot., 1928, 26, 275—287).—

Theoretical. Cf. Mutter (preceding abstract).

W. E . D o w n e y . Sensitom etry of d esen sitised film s. H. A r e n s and J. E g g e r t (Z. wiss. Phot., 1928, 26, 111— 126).—

Three-dimensional models have been prepared showing the relationships between the darkening D and log i and log t for the Agfa “ extra rapid ” plate and for the same plate when desensitised before exposure by immersion in 1 /2000 phenosafranine solution contain­

ing 2% of potassium bromide. The forms of surface obtained differ in both position and form. For the desensitised plate a section parallel to the log t axis exhibits maxima, which decrease as i decreases; at low values of i no darkening is produced. The intensity plane, parallel to the log i axis, is of the normal form, which, however, remains unaltered at high values of t. Although the desensitised plate has a rather steeper intensity curve, there is no typical difference in the time curves. The Schwarzschild exponent n assumes anomalous values for the desensi­

tised plate; over a wide range n = 0 and in the region of reversal n ~ —2-3. No simple numerical expression can be obtained for the degree of desensitisation.

H. F. G i l l b e . Relation b etw een th e p h oto-electric and the photographic effect in silv er b rom id e. L. W.

Butler (Proe. Iowa Acad. Sci., 1927, 3 4 , 277).—

I’he^results obtained by Toy, Edgerton, and Vick (A., 1927, 293) are confirmed. Ch e m ic a l Ab st r a c t s.

Photom etric and sp ectrop h otom etric stu d ies.

“I- R eflexion sp ectroscop y. K. S c h a ttm (Z.

''iss. Phot., 1928,26,97— 110).—A method is described for the measurement of reflexion spectra, especially

°f opaque substances. The reflexion spectra of a number of aromatic azo-compounds have been deter­

mined, and in general the curves obtained resemble those of the absorption spectra. The influence of irradiation on films of a number of dyes has been

investigated; the number of large particles increases, W hilst the reflexion, and to a smaller extent the absorption, spectra are altered; this effect is depen­

dent on the presence of oxygen, since it is at a maxi­

mum in pure oxygen but is not produced in a vacuum or in an atmosphere of hydrogen, and is probably partly photochemical and partly physical in nature.

Analogous effects on the spectra are produced in some cases by treatment of the film with hydrogen peroxide, whilst coagulation of certain dye solutions by electrolytes results in similar effects.

H. F. G i l l b e . Influence of m e ta llic m a g n e siu m on th e fo rm ­ ation of form aldehyd e and su g a rs by the action of u ltra-violet ra y s on calciu m h ydrogen carbon­

ate solution s. G. M e z z a d r o l i and E. V a r e t o n (Atti R. Accad. Lincei, 1928, [vi], 8, 511—515).—

The power to reduce iodine solution acquired by calcium hydrogen carbonate solutions on exposure to ultra-violet rays (cf. Mezzadroli and Gardano, A., 1928, 255) rises to a maximum after 30 min. when open basins, or after 1 hr. when closed transparent vessels, are used to contain the liquid, the reducing power being the higher in the latter case. The total amount of reducing substances formed is increased by the presence in the solutions of metallic magnesium, which also results in the formation of sugars which reduce Fehling’s solution and form an osazone.

T. H. P o p e . Induction period and after-effect in p hoto­

ch em ical reaction s. R. M. P u r a k a y a s t h a (J.

Indian Chem. Soc., 1928, 5, 721—732).—The induc­

tion period in the photo-bromination of cinnamic acid and stilbene (A., 1926, 366; 1928, 172) is diminished by any factor (e.g., temperature, intensity of light) causing an increase in the velocity of the reaction.

During the oxidation of tartaric acid by bromine (A., 1925, ii, 1179) the induction period increases with increased concentrations of tartaric acid, and to a certain point with bromine. Above this concentra­

tion of bromine a decrease is manifested owing to

tion of bromine a decrease is manifested owing to