ation of the degree of dissociation of water.
H. M. Da w s o n (J.C.S., 1927, 1290— 1297).— The calculation of the ionisation constant of water from the results of ester hydrolysis by means of the equation K ~ v?lik hlcon is described (cf. this vol., 632). The minimum velocity of reaction, t\, must he measured in buffer solutions, preferably, for mathematical simplicity, of constant acid or constant salt concen
tration. The acid and salt effects associated with the use of buffer solutions for the stabilisation of p a in reaction velocity measurements are discussed. From the results of Karlsson’s experiments (A., 1925, ii, the values K „ = l - 2 5 x lO’ 14 at 25° and 3 4 x 10~14
&L &>-5° are calculated. S. K . Tw e e d y. Influence of water on the com bination of the nalogens with hydrogen. M. Bo d e n s t e i n and w .Jaw (J. Amer. Chem. Soc., 1927, 4 9 ,1416— 1418).
Experiments are described indicating that the 3o
investigations of Lewis and Rideal (A., 1926,1111) do not prove that intensive drying retards the reaction between hydrogen and bromine or iodine. The presence of phosphorus pentoxide in the heated gases is shown to vitiate the results. S. K . Tw e e d y.
Chain-reaction theory of negative catalysis.
H. L. J. Ba c k s t r o m (J. Amer. Chem. Soc., 1927, 4 9 , 1460— 1472).— The autoxidation of benzaldehyde, of heptaldehyde, and of sodium sulphite solution at 20°, both in the light and in the dark, exhibits marked negative catalysis. An inhibitor for the light reaction invariably inhibits the dark reaction, although in the case of benzaldehyde the dark reaction is the more sensitive to inhibitors. Some inhibitors suppress the light reaction in the case of sodium sulphite more strongly than the dark reaction; alcohols exert parallel effects on both reactions. Quantum efficiency measurements indicate that a large number of mole
cules react for every light-quantum absorbed, and, in general, it is concluded that the above photochemical reactions represent instances of thermal chain reactions (cf. Christiansen, A ., 1924, ii, 242). S. K . Tw e e d y.
Activity of various metals and metal oxide catalysts in promoting the oxidation of methane by air. W . P. Ya n t and C. O. Ha w k (J. Amer.
Chem. Soc., 1927, 4 9 , 1454— 1460).— The catalytic oxidation of 3-75—4-1% of methane in air b y various metals, metal oxides, and mixtures of oxides was investigated between 150° and 350°. Cobaltic oxide was the most efficient catalyst; excluding mixtures, it was followed b y manganese dioxide and nickelic oxide. 10% of platinum-black when added to metallic nickel appears to act as a promoter. Mixtures of the oxides gave results corresponding with the proportion of each active material present. S. K . Tw e e d y.
Reduction of mixed oxides. Copper and zinc oxides. W . Ro g e r s, jun. (J. Amer. Chem. Soc., 1927, 4 9 , 1432— 1435).— Zinc oxide in a mixture with copper oxide (prepared in the fused state) is completely reduced by hydrogen at 300°. It is considered that the presence of one oxide prevents the crystal units of the other oxide from arranging themselves in the normal way. The forces between the units in the lattice structure are thus altered, and the properties of each component would be expected to be different from those for the pure state. S. K . Tw e e d y.
Catalytic activity of lead. F. A. Ma d e n w a l d, C. 0 . He n k e, and O. W . Br o w (J. Physical Chem., 1927, 31, 862— 866).— The activity of various lead catalysts in the reduction of nitrobenzene b y hydrogen has been compared b y the method previously used (Brown and Henke, A., 1922, i, 445). Light red lead, heavy red lead, and a light and a heavy litharge, prepared from recrystallised lead nitrate by varying heat treatments, on reduction b y hydrogen at 308°
gave the catalysts used. The activity of the catalysts increased with use, but more slowly than is the case with copper catalysts. It also increased more rapidly in an iron than in a glass tube. The initial activity of the different samples varies, but the final activity is the same. The optimum temperature for the reduction of nitrobenzene is 308°, and one catalyst prepared from heavy litharge maintained a 97% yield
738 BRITISH CHEMICAL ABSTRACTS.----A.
of aniline for approximately 200 experiments. Grind
ing the catalyst had no permanent effect on its activity, but hydrogen alone destroyed the activity. The optimum rate of flow is 14 litres of hydrogen and 4 g. of nitrobenzene per hr. at 308°. Appreciable yields of azobenzene (up to 25% ) were obtained only during the first few runs. L. S. Th e o b a l d.
Catalytic actions of silver chloride in oxidation- reduction processes. R. La n g (Ber., 1927, 60, [E], 1389— 1390).— A solution containing the higher chlorides of manganese in 2 • 5 iV - h y d r o c h 1 o r i c acid, which does not decompose appreciably at the atmo
spheric temperature, rapidly and quantitatively yields chlorine and manganous chloride after addition of silver nitrate. If the acid is more dilute, a higher temperature is required for the change. Ceric nitrate dissolved in hydrochloric acid becomes almost instantaneously decolorised after addition of silver
nitrate. H. Wr e n.
New kinds of mixed crystals. III. D. Ba l a r e v
and G . Ka n d il a r o v (Z. anorg. Chern., 1927, 163, 141— 144; cf. A., 1926, 1195).— The presence of finely-divided barium sulphate reduces the velocity of oxidation of hydrogen chloride by permanganates in dilute solution. That the barium sulphate does not behave as a chemically inert substance is demon
strated by the fact that no diminution of the reaction velocity is caused by the presence of sand. For different permanganates, the magnitude of the effect is different, being greatest for potassium perman
ganate. The phenomenon is ascribed to variations in the extent of the adsorption of different perman
ganates by barium sulphate. ■ H. F. Gil l b e. Electrolytic oxidation of concentrated formic acid solutions. F. Mü l l e r (Z. Elektrochem., 1927, 3 3 , 173— 176).— A 95% formic acid solution (some
times with addition of 5% of sodium formate) has been electrolysed between platinum electrodes at 0-065 am p./cm .2 The theoretical amount of hydrogen was obtained at the cathode, but it was accompanied by considerable amounts of carbon dioxide. A t the anode, however, the carbon dioxide obtained was always less than that corresponding with the process 2H C02'+ © = H - C 0 2H + C 0 2. This deficiency is shown to be due to the considerable solubility of carbon dioxide in the electrolyte. Diffusion of carbon dioxide in solution to the cathode causes it to he carried off with the hydrogen evolved there. When the electrodes are separated by a diaphragm, no carbon dioxide is obtained at the cathode.
H. J. T. El l in g h a m. Action of iron as an impurity in the lead accumulator. I and II. F. M. Le a and J. T.
Cr e n n e l l.—See B., 1927, 528.
Oxidation of sodium plumbite to plumbate by alternating current. II. F. Jir s a and F.
Ko r n a l ik (Z. Elektrochem., 1927, 3 3 , 192— 196).—
The current efficiency, ij, for the production of sodium plumbate by the passage of sinusoidal alternating current through sodium hydroxide solutions saturated with lead monoxide has been investigated under various conditions (cf. A., 1920, ii, 620). W ith elec
trodes of gold or cadmium, 17 is extremely small, with palladium it is somewhat higher, but with nickel
electrodes it is about ten times as great as with palladium. With nickel electrodes, rj decreases with increasing alkali concentration up to 1-5N, then increases up to 4-5JV, and finally diminishes at higher concentrations : with palladium electrodes, however, these variations are reversed, the maximum being at
l-5iV. Using alternating current at 49 cycles, the highest value of 7; recorded is 11-33% (calculated 011 current shown by an alternating-current ammeter), using 0-412 am p./cm .2 at nickel electrodes in 4-66IV- sodium hydroxide saturated with lead oxide at 18°.
Increasing the frequency over the range from 18 to 60 cycles decreases rj considerably. W ith platinum electrodes, no oxidation to plumbate occurs, but the platinum is attacked, giving a brown deposit con
taining lead and platinum, the latter being partly in the metallic state and partly in the form of platinic oxide. It is believed that platinum dissolves essen
tially in the bivalent form, which subsequently changes to satisfy the equilibrium 2P t"==^:P t"''+P t.
The dissolution of platinum in pure iV-sodium hydr
oxide by alternating current is also examined.
H. J. T. El lin g h a m. Production of ozone in air by ultra-violet rays.
J. Da d l e z (Compt. rend., 1927, 1 8 5 , 89— 91).—The diminution of the ozone content of the air at increasing distances from quartz lamps of various makes and candle-powers has been measured. The minimum ozone content of air producing the first symptoms of distress in adults is 1-0— 1*5 mg./m.3, the effects being felt after 30 min. Since only 0-05— 0-3 mg./m.3 of ozone are produced normally, there is little chance of danger in a large, well-ventilated room. The symptoms produced in an adult after various periods in atmospheres containing various amounts of ozone
are described. J. Graxt.
Glow in hydrogen at high pressure. J.
Ka p l a n (Nature, 1927, 1 2 0 , 48).— During attempts to obtain atomic hydrogen by means of an incan
descent tungsten filament in wet hydrogen at 20—
350 mm. pressure, a blue glow was observed. The glow may be caused by some material liberated from the filament; it is not due to excitation of the hydrogen by electrons from the filament. The spec
trum of the glow extends from 5000 to 4400 A., and is probably continuous. A. A. El d r id g e.
Photolysis of hydrogen cyanide by the total and filtered radiations of the mercury arc. A.
A n d a n t and E. R o u s s e a u (Compt. rend., 1927, 184, 1553— 1555).— The method previously described (this vol., 538) has been applied to the irradiation of cherry-laurel water covered with a layer of olive oil, and containing pure manganous chloride (0-126%)- After 4 hrs., the phenomenon of photocatalysis follows that of photolysis. The mercury radiation 3650 A . produces, under the same conditions, a photo- lytic effect of the same order as that produced bj the whole of the mercury radiations up to 3130 A Allowing for the selective absorption of the _ raj 3650 A ., it appears that photolysis by ultra-violel radiation is in h ib ited by th e presence of radiations of greater wTave-length. J- G r a n t .
Effect of added gases on the decomposition o:
ammonia sensitised by optically excited mercurj
vapour. A. C. G. Mit c h e l l and R. G. Di c k i n s o n
(J. Amer. Chem. Soc., 1927, 4 9 , 1478— 1485).—
Whereas argon and nitrogen at 0-3 mm. pressure have no influence on the rate of photochemical de
composition of ammonia sensitised to 2537 A. by optically excited mercury vapour, hydrogen at the same and lower pressures has a large inhibiting effect (Stuart, A., 1925, ii, 629). This is partly due to the fact that hydrogen can be activated by collisions of the second kind with excited mercury atoms, this activated hydrogen having no effect on the ammonia decomposition. Hydrogen can also take activation from activated ammonia (cf. Kuhn, A., 1924, ii, 249).
The rate of decomposition of the ammonia increases with increasing pressure. The specific rate of activ
ation of ammonia is 4 % of that of hydrogen b y excited mercury atoms. S. K . Tw e e d y.
Light oxidation of alcohols as contribution to the knowledge of photochemical phenomena.
J. Bo e se k e n and S. L . La n g e d ij k (Proc. K . Akad.
Wetensch. Amsterdam, 1927, 30, 189— 196).— Certain aromatic mono- and aliphatic a-di-ketones can behave as photocatalysts in the oxidation of alcohols to the corresponding aldehyde. The photoactive region lies between 400 and 410 [j.u. The theoretical bearing of these results is discussed. The reaction has been used to effect the decomposition of optical antipodes.
Z-Mcnthyl benzophenone-^-carboxylate was dissolved in methylethylcarbinol, and exposed to light in pres
ence of oxygen. The racemic alcohol was used, and after the experiment the fractionated alcohol was found to be Isevorotatory. W . E. Do w n e y.
Photochemical reaction of bromine with fumaric and maleic esters. J. Eg g e r t [with F.
Wachholtz and R. Sc h m id t] (Oesterr. Chem. Ztg., 1927, 30, 110).— Measurements of the rate of photo
chemical conversion of ethyl maleate into fumarate in carbon tetrachloride solution, in presence of bromine, show that the quantum efficiency varies with tem
perature and the wave-length of the light used, but is independent of the concentrations of ester, bromine, and added ethyl fumarate. The photochemical effect is merely the initiator of the process, which is essen
tially chemical. The process is complicated by the fact that, under the experimental conditions, both esters take up bromine, the quantum efficiency of this reaction varying -with the concentration of bromine. A reaction mechanism is suggested accord
ing to which bromine atoms are responsible for the observed effects. Bromine molecules are first dis
sociated into their atoms, which form an intermediate complex on collision with ester molecules. The com plex is very unstable, and undergoes rearrangement and subsequent decomposition. Collisions between bromine molecules and the complex are responsible for the appearance of dibromosuccinic ester. Experi
ments with the methyl esters and with an aqueous solution containing maleic acid, bromic acid, and a ierrous salt furnish evidence in support of the sug
gested mechanism. J. S. Ca r t e r. Addition of bromine to a-phenylcinnamonitrile under the influence of light. A. Be r t h o u d and 7 Nicolet (Helv. Chim. Acta, 1927, 10, 417— 429;
c • Berthoud and Bellenot, A., 1924, ii, 327; Plot
nikov, “ Lehrbuch der Photochemie,” p. 250).— The addition of bromine to a-phenylcinnamonitrile and the reverse reaction both take place much more slowly in the dark than Bauer and Moser allege (A., 1907, i, 307). The rate of addition, <Z[dibromide]/iZi, for small absorption is ¿ ^ ' “[bromine]1'5; for total ab
sorption, ¿^/¡¡’ [bromine], The thermal coefficient is 1-4. The photochemical decomposition of the di
bromide occurs only in presence of bromine, which acts as an optical sensitiser. The rate of this reaction,
—¿[clibromide]/(Zi, when the nitrile is in large excess, is for small absorption &2/ 2'5[dibromide][bromine]0'5/
[nitrile], for total absorption £2/g'5[dibromide]/
[nitrile]; whilst in absence of large excess of nitrile the denominator must be [nitrile]-fra [dibromide].
The thermal coefficient is 1-96. The photochemical equilibrium is independent of intensity of illumination, and is represented by the expression Z '= ([n it r ile ]+
m[dibromide])[bromine]/[dibromide], m becoming zero when the nitrile is in large excess. A theory of these results, which are quite different from those of Plot
nikov, is developed. C. Ho l l in s. Oxidising agents in the study of the sensitivity of photographic emulsions. W . Cl a r k.— S ee B., 1927, 507.
Precipitation of metals and their oxides from salt solutions by hydrogen at high temperatures and pressures, and synthesis of minerals. I.
Influence of other metals in the precipitation of copper. W . Ip a t ie v and N . Kl i n k o i a. II. Pre
cipitation of oxides from salts of chromium, manganese, and iron. W . Ip a t ie v and A . Ki s s e l e v. III. Precipitation of metals of the iron group from solutions of their cyanides and salts with organic acids. W . Ip a t ie v and I. N.
Ko n d y i i e v. IV. Precipitation of phosphorus, arsenic, and antimony from their salts at high temperatures and pressures. W . Ip a t ie v and W. Nik o l a ie v (J. Russ. Pliys. Chem. Soc., 1926, 5 8 , 664— 686, 686— 692, 692— 698, 698— 704).— I. The effect of temperature, pressure, concentration, and duration of reaction, as well as the presence of the salts of iron, nickel, zinc, and of free acids on the precipitation of copper from solutions of its salts (mainly copper sulphate) was investigated. The ex
periments were performed in glass tubes, but above 200° quartz vessels were used. Increase of concen
tration gave a precipitate containing cuprous oxide and basic salts, owing to secondary hydrolysis reac
tions. The amount of copper precipitated was pro
portional to the time. Rise of temperature favours deposition up to 150°, but above that inhibits it.
Increase of pressure always favours deposition. The significance of these results from the point of view of the dynamics of the reactions is discussed. Above 150°, the sulphuric acid liberated was reduced by the hydrogen, the deposited copper acting as a catalyst, and cuprous oxide or basic salts were formed. A t higher temperatures and pressures, cupric sulphide was obtained in a crystalline form. Addition of free sulphuric acid in small quantities favoured the precipitation of metallic copper, since it inhibited the secondary hydrolytic reactions. The addition of salts of nickel, zinc, and iron had no effect on the
740 BRITISH CHEMICAL ABSTRACTS.— A.
precipitation of copper, provided some free acid was present to prevent the formation of basic salts of the metals.
II. The cxperimente were performed at higher temperatures (300°) and pressures (> 1 5 0 atm.) in silver, gold, and platinum balls, as quartz vessels gave with the salts crystals of metal silicates. Basic salts and oxides of the metals were obtained as well- developed crystals, often identical with the naturally- occurring minerals. Chromic acid gave at 300° and 150— 180 atm. a greyish-violet powder, of the formula Cr20 3,H20 , whilst in a quartz tube a bright green substance of the same composition was obtamed.
A mixture of potassium chromate and sulphuric acid (50%) gave an insoluble crystalline substance of the formula Cr2(S04)3,Cr20 3,K 20 ,H 20 , which was exam
ined by the X -ray spectrograph. Potassium mangan- ate and manganese nitrate under similar conditions gave the crystalline mineral hausmannite Mn30 4,H20 . In presence of free nitric acid in a quartz tube a manganese silicate was obtained. Manganese chloride gave a hydrated oxide, M n0,H 20 , whilst manganese sulphate gave manganese sulphide.
Iron salts precipitated mixtures of iron oxide, and finally, as the pressure increased and the temperature was raised, crystalline magnetic iron oxide, Fe30 4.
No metallic iron was obtained, even when potassium ferrocyanide was used, which on decomposition gave first formic acid and then nascent hydrogen, capable of reducing any iron oxide, owing to hydrolytic reactions. Ferric chloride gave a white, crystalline mass; ferric acetate did not react, except with water- gas, when ferrosoferric oxide was obtained; ferrous sulphate precipitated a mixture of magnetic oxide and ferrous sulphide.
III. Iron formate gave magnetic oxide; nickel formate gave metallic nickel mixed with nickel oxide, the amount of which increased with rise of temper
ature and pressure, owing to hydrolysis, whilst nickel cyanide gave only anhydrous, crystalline, black nickelous oxide. Ferrous cyanide, formate, and acetate gave magnetic oxide, whilst the thiocyanate gave a mixture of oxide and sulphide. W ith the double cyanide of potassium and manganese, crys
talline manganese carbonate was obtained. In a quartz tube, manganese and zinc nitrate deposited the corresponding crystalline silicates.
IV. Free phosphoric acid and its alkali salts re
mained unaffected, but ferric phosphate gave a con
tinuous series of crystalline complex phosphates of the type Fe/ "»F e"mP 0 4,a;H20 , depending on the conditions, identical with the naturally occurring minerals— the vivianites. Lead phosphate at 250—
300 atm. and 360— 400° deposited a colloidal orange oxide, Pb20 , and hypophosphorous acid, whilst with water-gas at 400 atm., phosphine and some metallic lead were obtained. With lead hypophosphite, at high pressures, in presence of water, black, elementary phosphorus was formed. This form was also obtained by the action of water on red phosphorus at 260°
and 100 atm. The salts of arsenic acid and iron oxide gave green, crystalline hydrated ferric arsenate, identical with the mineral scorodite. Further action resulted in the formation of elementary arsenic. If the action is prolonged for a few days, crystalline
arsenical pyrites, F e'"„A sm, is obtained. Copper arsenate gave the mineral domeite (cuprous arsenide, Cu3As). With elementary arsenic a little arsine was evolved. Antimony sulphate formed crystals of anti
m ony glance, Sb2S3, and potassium pyroantimonate formed crystalline elementary antimony. In general, antimony salts are more easily reduced than those of arsenic and phosphorus. M. Zv e g in t z o v.
Double sulphates of the copper-magnesium group and the sulphonium bases. I. P. C. Ra y and N. Ra y (J. Indian Chem. Soc., 1927, 4, 37—
42).— Double sulphates having the general formula M "S 0 4,(Et3S)2S 0 4,10H20 , where M " = F e " , Zn, Ni, Co, Cd, have been prepared by slow evaporation of triethylsulphonium sulphate (obtainable only in solu
tion) with the appropriate metallic sulphate in the ratio 2 : 1 . These compounds are hygroscopic; alco
hol added to their aqueous solutions causes separation of the inorganic components. Salts of the type 2M "S04,(Et3S)2S 0 4,l lH 20 were also formed, where M "= M g or Mn, and when trimethylsulphonium sulphate was substituted for the ethyl derivative nickel formed a salt of this tj’pe.
B. W . Anderson. Reactions of active magnesium. A. P. Teren t i e v (Z. anorg. Chem., 1927,162, 349—352).—Active magnesium may be prepared by passing the vapour of an alcoholic solution of iodine over the powdered m etal; 1 g. of iodine is sufficient to activate 24 g. of magnesium, which must be dried beforehand by strong heating. The active product must be freshly prepared for use, as it is very hygroscopic and its activity is destroyed by traces of moisture. A mixture of active magnesium and ethyl alcohol does not reduce the methyl esters of the fatty acids, but yields the ethyl esters. When heated in ammonia at 350— 400°, the active metal forms a grey powder, consisting of magnesium amide. Ordinary magnesium reacts with aniline vapour at about 370°, whereas the active form reacts with the vapour at about 240° and with the liquid at 130— 140°.
H. F. Gil l be. Setting of dihydrates of calcium sulphate.
P. P. Bu d n i k o v.—^See B ., 1927, 483.
P. P. Bu d n i k o v.—^See B ., 1927, 483.