velocities in buffer solutions and compound catalytic catenaries. H. M. Da w s o n (J.C.S., 1927, 1146— 1153).— The catalytic coefficients kn and k0K of the hydrogen and hydroxyl ions, respectively, may be derived from the minimum velocity of a hydrolytic reaction (i.e., any reaction catalysed by both the hydrogen and hydroxyl ion) and the cor
responding hydrogen-ion concentration. The value of ^'oh/^h varies enormously with the hydrolyte (e.g., 12x10® for ethyl aminoacetate and 1-6 for benz- amide). Approximate velocity and hydrogen-ion concentration data may be obtained by the use of buffer solutions, provided a correction is made for the catalytic effects of constituents other than the hydrogen and hydroxyl ions. The curves obtained on plotting reaction velocity against the pa value of a series of acid-salt buffer solutions characterised by constant concentration of acid are catenary in type, but are compound in character, since the anionic catalytic effect is also shared b y the anion of the acid in the buffer mixture. The compound catenaries form a continuous series limited on the one side by the H+— OH ~ catenary and on the other by the simple H +— A - catenaries corresponding with the mixtures cHA+.tM A. The compound catenaries conform to the requirements of the general catalytic catenary, the applicability of which is further ex
tended to include anionic catalytic effects shared by the hydroxyl ion with other acid anions.
J. S. Ca r t e r.
Catalysis in the reaction between persulphate and iodide ions. A. v o n Ki s s and L. v o n Zo m b o r y
(Rec. trav. chirn., 1927, 46, 225— 239).— An examin
ation of the kinetics of the stoicheiometrieally ter- molecular reaction between persulphate and iodide in dilute aqueous solution shows that, when allow
ance is made for the amount of iodide ion involved in the tri-iodide equilibrium, the experimental numbers conform to the requirements of a reaction of the second order. The reaction scheme is there
fore : (i) S20 8" + r = S 20 8r " (measurable rate);
(ii) S20 8r " - f r = 2 S 0 4' ' + I 2 (rapid). As predicted from considerations of Bronsted’s theory of reactions (A., 1922, ii, 699), the rate of reaction is increased in presence of neutral salts. In presence of ferrous
or copper salts, an actual catalytic effect is observed, which is due to the opening of new reaction paths.
In the case of ferrous salts, the effect is satisfactorily represented by the additional reaction schem e:
(¡ii) Fe"-j-S20 8" = F e S 20 8 (measurable rate); (iv) FeS20 8+ F e " = 2 F e ‘ ” + 2 S 0 4" (rapid); (v) 2Fe"*+
2 I'= 2 F e ” - f I 2 (rapid). A similar scheme involving cuprous and cupric ions explains the catalytic activity of copper salts. The rate of the catalytic process is determined by reaction (iii), and, as predicted by Bronsted’s theory, the neutral salt effect is negative.
In presence of acid, the rate of reaction is slightly lowered. The velocity of the uncatalysed reaction is increased somewhat on illumination.
J . S. Ca r t e r.
Negative catalysis in a homogeneous system.
A. C. Ro b e r t s o n (Proc. Nat. Acad. Sci., 1927, 13, 192— 197).— Vanadic acid greatly reduces the rate of the catalytic decomposition of hydrogen peroxide b y potassium dichromate. This negative catalytic effect is explained on the assumption of a change in the catalytic path (A., 1926, 917). The catalytic decomposition by potassium dichromate is due to the reactions: (i) K 2Cr00 7+ H 20 2= 2 K C r0 4-|-H20 ; (ii) 2KCr04+ H 20 2= K 2Cr20 7-f-H20 + 0 2. Corre
sponding reactions occur with vanadic acid, the reactivity of pervanadic acid being, however, much smaller than that of potassium dichromate. In the present case, reaction (ii) is largely replaced by the reaction : (iii) 2KCr04 + H V 03= K 2Cr20 7+ H V04.
As a result, the concentration of the more reactive dichromate decreases with consequent retardation of the peroxide decomposition. J . S. Carter.
Colloid particle as revealed by catalytic studies.
H. S. Ta y l o r (Fourth Colloid Symposium Mono
graph, 1926, 19— 28).— Catalytic action is regarded as a branch of colloid chemistry. An oxide catalyst surface is composed of two catalysts, metal ions and oxide ions, and the nature of the changes induced is determined by the charge on the ion on which the reactant molecule is adsorbed. The extent of the two alternative changes depends on the relative extent of adsorption of the reactant on the two ions, on the relative frequency of occurrence of the ions, and on their specific catalytic activities. These factors depend on the degree of saturation of the lattice ions, and the extent to which the ions are already covered by poisons.
Ch e m i c a l Ab s t r a c t s.
Contact catalysis and the activation of gases by adsorption. G. M. S c h w a b and E. Pi e t s c h
(Z. physikal. Chern., 1927 ,1 2 6 ,4 7 3 -^ 7 4 ).— Polemical (cf. this vol., 426). H. F. G i l l b e .
Influence of temperature on the catalytic decomposition of hydrogen peroxide. A. G a l e c k i
and G. J e r k e (R o c z . Chem., 1927, 7 , 1— 6).—The temperature coefficient of the uncatalysed decom
position of hydrogen peroxide has a maximum value at about 50°. The temperature coefficients of the same reaction catalysed by gold hydrosols vary inversely as the temperature in those cases where the catalyst is very active; with less active catalysts, a maximum value is obtained at 35— 45°. With still weaker preparations, the temperature coefficient
GENERAL, PHYSICAL, AND INORGANIC CHEMISTRY. 633
increases with rise in temperature, and finally, with such gold hydrosols as possess no appreciable catalytic action,- the temperature coefficient at first falls to a minimum at 35— 45°, after which it rises. In all cases, the value of the temperature coefficient between 35° and 45° is lower than for the uncatalysed reaction ; between 25° and 35° it is, on the other hand, slightly higher. With silver hydrosols, the value of the temperature coefficient diminishes with rise of temperature. R . Tr u s z k o w s k i.
Kinetics of chemical reactions. I. Inter
pretation of conjugated autocatalysis in the isomérisation of alkyl phosphites. W. St a r o n k a
(Rocz. Chem., 1927, 7, 42— 53).— The velocity coefficient for the reaction of isomérisation of alkyl phosphites (Zawidzki and Staronka, Bull. Acad. Sci.
Cracovie, 1915, 310— 386) with ethyl iodide as catalyst is only an apparent case of conjugated autocatalysis ; in reality, the changes in velocity are due to changes in the reaction medium which at first is triethyl phosphite and ethyl iodide, whilst at the end it is diethyl ethylphosphite, PEtO(OEt)2, and ethyl iodide.
As a result, the physical properties of the medium change, and with them the velocity of reaction.
Hence it is concluded that Doroszewski’s law is applicable also to the velocity coefficients of reactions.
R . Tr u s z k o w s k i.
Preparation of formaldehyde by catalytic dehydrogenation of methyl alcohol. I. J. C.
Gh o sh and J. B. Ba k s i.— See B., 1927, 426.
Deterioration of mineral oils. I. Mechanism oE oxidation and action of negative catalysts as determined by a dynamic method. R . T. Ha s l a m
and P. K. Fr o l i c h.— See B., 1927, 355.
Electro-deposition of iron-nickel alloys. I.
S. Gl a s s t o n e and T. E. Sy m e s (Trans. Earaday Soc., 1927, 23, 213— 226).— An investigation has been made of the compositions of alloys deposited from well-buffered solutions of definite hydrogen-ion concentration containing mixtures of ferrous and nickel sulphates. A t very low current densities, the deposit from solutions containing more than about 20% of the total metal as iron contains a greater proportion of nickel than does the electrolyte ; ior solutions containing a smaller proportion of iron, the results are not definite. The proportion of iron in the alloy increases rapidly with increasing current density, reaches a maximum, and then either remains constant or slowly diminishes. The maximum cor
responds in all cases with the deposition of an alloy containing a greater proportion of iron than the solution, the excess being greatest hi the more con
centrated solutions or in solutions containing a greater relative amount of iron. Diminution of the iron coûtent of the alloy beyond the maximum point is most marked for dilute solutions or solutions of low hyclrogen-ion concentration, and disappears almost completely when the electrolyte is stirred so 13 to facilitate diffusion of the ferrous ions. The process of stirring also brings about an increase in the iron content at the maximum.
G. A. El l i o t t.
lnT:ectro' dePositio11 o f tin. W . Fr a i n e.— See B., 1927, 447.
TT
Study of the electrolytic deposition of the radio-elements. Jo l i o t (Compt. rend., 1927, 184, 1325— 1327).—An apparatus is described for the continuous study of the deposits produced in a given time on a gold electrode immersed in solutions (10~8 to 10~16iV) of polonium in nitric acid. The deposition electrode forms part of the electrolysing vessel, and is thin enough to allow the passage of the radiation from the active deposit into an ionisation chamber. The corresponding saturation-current is proportional t o ' the amount of the deposit. The deposition potential has been determined and the rate of deposition for the electrode-potential of +0-43 volt (Hg) shown to fall from a large value almost to zero in a few hours. Below this potential, the rate remains constant for a particular potential, but increases as the potential falls. J. Gr a n t.
Flat luminous flames. D. S. Ch a m b e r l i n and W . E. Th r u n (Ind. Eng. Chem., 1927, 19, 752— 754).
— The size and shape of flat luminous flames burning at a slit are investigated by photographic methods and the Poiseuille formula for the flow of gases through a circular orifice is modified for narrow slits. There is no simple relation between the size of the flame and the width of the slit; wide slits do not conform to the same principles as narrow slits.
A comparison was also made of the gas jet in the form of a flame and in the unignited state.
S. K . Tw e e d y.
Chemiluminescence of phosphorus vapour.
E. J. Bo w e n and E. G. Pe l l s (J.C.S., 1927, 1096—
1099).— Assuming that the final product of oxidation, phosphoric oxide, is produced as a result of a series of consecutive reactions, of which only one, involving one molecule only of oxygen, emits light, experiments in which the ratio of the number of quanta of visible light emitted to the number of molecules reactmg in the glow of phosphorus vapour and oxygen was determined photographically, show that at least 1 in 2000 molecules of phosphorus undergoing oxidation emits a quantum of visible light. The glow of phosphorus appears to be a chemiluminescence of the type described b y Kautsky (A., 1926, 558), oxidation at the surface of solid particles of an oxide exciting to luminescence adsorbed molecules of some other oxide. J. S. Ca r t e r.
N ature of p h osp h oru s ion isation . W . Bu s s e
(Ann. Physik, 1927, [iv], 82, 873— 911).— Luminous white phosphorus is undergoing slow oxidation with concomitant formation of ozone and the appearance of positively and negatively charged ions in the surrounding gas. Bloch (A., 1903, ii, 206; 1904, ii, 117; 1905, ii, 72; 1908, ii, 1032) and Harms (A., 1904, ii, 331) have investigated the mobilities of the large ions. Repetition of the measurements with improved methods shows that the ions do actually arise at the oxidising phosphorus. The two kinds of ions do not at first show different mobilities, but the results are difficult to reproduce owing to the influence of temperature and moisture; the method used nevertheless allows the ageing of ions to be followed, although an exact upper limit to the increase in ionic size cannot be fixed. A continuous range of sizes has been demonstrated, and it is therefore
634 BRITISH CHEMICAL ABSTRACTS.— A .
concluded that the phosphorus cannot be the only place at which ions originate. The rate of growth of the large ions indicates that ionisation must occur also in the air stream away from the phosphorus.
Small temperature differences play an important part in the gradual disappearance of ions. The evidence of the rate of growth of positive and negative ions indicates that the latter must be multiply charged. On the assumption of single positive charges, the positive ions increase in size from 5 x 10~8 cm. to about 2— 4 x 10~6 cm. in 8 sec.
Downey (A., 1924, ii, 250) found that the light emitted from phosphorus could ionise air through a plate of fluorite. It has not been possible to repeat this experiment, and all the evidence considered is against the view that rays between 120 and 200 ¡xa are generated. It is also concluded that photo-electric action plays no part.
The oxidation of phosphorus is greatly influenced by the presence of water vapour, and reaches a maximum when the moisture content is regulated by means of concentrated sulphuric acid (1014 to 1015 molecules of water per c.c. of vapour). It is confirmed that extreme drying retards the oxidation of phosphorus, but does not effect complete inhibition, so that, whilst water is a catalyst for the process, it is not essential.
Dry phosphorus becomes coated with a film of oxide in the dark so that a store of phosphorus tri
oxide accumulates. This midergoes sudden oxidation to the pentoxide accompanied b y luminescence when local temperature changes occur. The high mobilities of the negative ions are ascribed to multiple charges, four to six times as great as those carried by the positive ions. The latter appear to be predominantly singly charged, and in any case four charges is regarded as the maximum for a positive carrier (cf. A., 1905, ii, 244; 1906, ii, 326; 1924, ii, 255).
It. A. Mo r t o n.
Light-sensitiveness of zinc and silver salts.
F. G. Br i c k w e d d e (J. Opt. Soc. Amer., 1927, 14, 312— 322).— Lithopone, a white pigment containing about 26% of zinc sulphide, darkens on exposure to ultra-violet light. The sensitivity of several com
mercial brands was determined for light of different wave-lengths between 2536 and 3650 A. Whilst the rate of darkening varied with different samples, the ratio of the sensitivities remained constant for all wave-lengths. The sensitivity of lithopone showed a maximum at about 3126 A., and similar measure
ments on precipitated silver chloride showed an in
crease in sensitivity at 3650 A. Indirect evidence was obtained that the darkening of lithopone is due to the formation of metallic zinc and liberation of hydrogen sulphide. If impurities capable of forming dark sulphides are present, the sensitivity of lithopone is increased. A comparison of the therapeutic value of several arcs, based on their effect on lithopone, is
given. C. J. Sm i t h e l l s.
Law of blackening of the photographic plate at low densities. E. A. Baker.— See B., 1927,461.
Activation of hydrogen in the electric dis
charge. G. A. El l io t t (Trans. Faraday Soc., 1927, 23, 60— 75).— See this vol., 187.
Cuprammonium salts. VII. A complex thio- sulphate. D. W . H o r n and R . E. C r a w f o r d
(Amer. J. Pharm., 1927, 99, 274— 279; cf. Horn and others, A., 1904, ii, 662; 1906, ii, 231; 1907, i, 595, ii, 871 ; 1908, i, 121, 392).—A new, complex cuprammonium thiosulpliate, Cu1qS150 18,9NH3, was prepared by mixing a solution, dr11-26, of sodium thiosulphate in concentrated ammonia solution with cupric chloride solution. The substance forms stable, deep blue crystals. M. C a r l t o n .
Action of salts on metals. T. Pe c z a l s k i
(Compt. rend., 1927, 184, 1159— 1161).— Copper and iron, when heated in presence of salts, increase in volume and electrical resistance if no reaction occurs.
Cementation of the metal by the salt is the result of decomposition of the latter, and is facilitated by volatile salts. Copper heated at 800° in chromic chloride vapour absorbs the latter with a rise in temperature. The copper then fuses and sublimes, and its vapour combines with that of the salt to form a volatile chemical compound with liberation of heat. These phenomena explain the increased fragility and powers of electronic emission in such
cases. J. Gr a n t.
Treatment of pollucite and preparation of cæsium chloride. A. Ka s t l e r.— See B., 1927, 439.
Surface film of aluminium. W . H. Wit h e y
(Nature, 1927, 119, 923— 924).— A claim for priority against Sutton and Willstrop (this vol., 530).
A. A. El d r id g e.
[Surface film of aluminium.] H . Su t t o nand J. W. W . Wi l l s t r o p (Nature, 1927, 119, 924).—A reply to Withey (preceding abstract).
A. A. El d r id g e.
Silicic acids. III. R . Schw arz and H. Richtek (Ber., 1927, 60, [5 ], 1111— 1116; cf. A., 1925, ii, 222).— The conception of the existence of definite hydrates of silica is strengthened by the observation that whereas the meta acid is found by Röntgen spectrographic analysis to be amorphous, the acid H2Si20 5 is crystalline. At 150°, the latter acid be
comes amorphous and subsequently does not yield a crystalline, less hydrated system, but passes gradually into stable, crystalline quartz. The dehydration isotherm of the acid H2Si20 5 at 12° exhibits a definite break corresponding with the presence of about 17%
of water; the divergence from the theoretical value (13%) is ascribed to the extensive development of the surface and consequent great adsorptive power, as shown by its behaviour towards methylene-blue and its marked hygroscopicity. The water content corresponding with the break in the curve increases if the surface of the acid is increased by grinding, and it must therefore be expected that silicic acid gels will not give characteristic dehydration isotherms even if distinct hydrates are present. Metasilicic
acid at 17° gives a continuous dehydration isotherm, whereas the curve of the acid at 2° exhibits two breaks at points immediately before and after that corresponding with the theoretical water content- At the first break, about 4 % of adsorbed water is present, which can be removed only b y decreasing the vapour tension to a value at which the meta
silicic acid is itself unstable. The dehydration isobar
GENERAL, PH YSICAL, A N D INORGANIC CHEMISTRY. 035
at 10 mm. does not give evidence of the existence of a hydrate of the acid H 2Si20 5. The conclusion is therefore reached that the isothermic is to be pre
ferred to the isobaric method in the investigation of systems of this type. H. Wr e n.
Ionic exchange of zeolitic silicates with hydro- lysable salts. I. Permutite. H. Ka p p e n and P. Ru n g.— See B., 1927, 364.
Occurrence of indium in tin. J . R. Gr e e n
(Nature, 1927,1 1 9 , 893).— Garrett’s observation (this vol., 393) is confirmed. A. A. El d r i d g e.
“ Active ” n itrogen . E . J . B. W i l l e y (Nature, 1927, 1 1 9 , 924— 925).— Experiments indicate that glowing and chemically active forms of nitrogen are distinct. The luminous variety is due to the recom
bination of atoms with a heat of formation of about 250,000 g.-cal./g.-m ol.; the other variety, which possesses an energy of about 45,000 g.-cal./g.-mol., may be metastable molecular nitrogen or a more complex substance such as N3. A. A. El d r i d g e.
Decomposition of nitrous oxide in the silent electric discharge. S. S. Jo s h i (Trans. Faraday Soc., 1927, 2 3 , 227— 238).— When nitrous oxide is subjected to the silent electric discharge in a Siemens ozoniser at 6000— 12,500 volts (r.m.s.) and 150 cycles per sec., the gas is completely decomposed, with intermediate formation of nitrogen peroxide, to nitrogen and oxygen. The amounts of nitrous oxide decomposed and of nitrogen and oxygen formed increase steadily for decreasing values of the initial pressure and a constant time of exposure to the dis
charge, or during the course of a single decomposition.
The amount of nitrogen peroxide, however, rises to a maximum and then decreases to zero. The pressure
time curves show an initial rapid pressure increase, an intermediate stage for which the gradient is much smaller, and finally a sudden increase to a constant value corresponding with complete decomposition.
The current-time curves are similar, with the excep
tion that during the initial stage of increasing pressure the current diminishes. A mechanism for the decom
position is proposed from a consideration of these
results. G . A. El l i o t t.
Oxidation reactions. I. P. As k e n a s y and E.
Elod. Production of nitrates and arsenic acid.
H. Zie l e r (Z. anorg. Chem., 1927, 1 6 2 , 161— 192).—
The oxidising action of nitric acid usually ceases when reduction to nitric oxide has occurred. Since the reaction 4 N 0 + 3 0 2+ 2 H 20 = 4 H N 0 3 involves a dimin
ution in volume, attempts have been made to carry out oxidations with oxygen under pressure in presence of nitric acid, the latter to act merely as the oxygen carrier. With oxygen under a pressure of 20 atm., sodium nitrite in solutions acidified with nitric acid is quantitatively oxidised to nitrate, the oxidation occurring in slightly acid solutions entirely in the hquid phase. The rate of oxidation increases with mcrease in the acidity, dilution of the salt, temper
ature, and, to a less extent, with the oxygen pressure.
, rth neutral nitrite solutions, no oxidation occurs.
Arsenious oxide, when sufficiently finely divided, can e oxidised practically quantitatively at 90° with oxygen under 20 atm., and twice its weight of 40—
60% nitric acid in about 1 hr., the nitric acid being nearly completely regenerated. The rate both of re-formation of the nitric acid and of the oxidation increases with increase in oxygen pressure and in the temperature. Increase in the acid concentration accelerates the oxidation, but retards the regeneration of the acid. The nitric acid can be removed from the reaction mixture nearly quantitatively by distillation under 15 mm. pressure. With neutral solutions, no oxidation occurs. Arsenic sulphides are oxidised by nitric acid and oxygen under pressure to arsenic acid and sulphuric acid. With oxygen at 20 atm. and at 120°, realgar is completely oxidised with twice its weight of 10% acid in 30 min., whilst orpimcnt requires 40% acid for 15 min. In the case of arsenical pyrites, about 16% of the arsenic is not attacked, and some oxygen is used in oxidising the iron. The amount of nitric acid required is in every case less than the amount that would theoretically be needed
60% nitric acid in about 1 hr., the nitric acid being nearly completely regenerated. The rate both of re-formation of the nitric acid and of the oxidation increases with increase in oxygen pressure and in the temperature. Increase in the acid concentration accelerates the oxidation, but retards the regeneration of the acid. The nitric acid can be removed from the reaction mixture nearly quantitatively by distillation under 15 mm. pressure. With neutral solutions, no oxidation occurs. Arsenic sulphides are oxidised by nitric acid and oxygen under pressure to arsenic acid and sulphuric acid. With oxygen at 20 atm. and at 120°, realgar is completely oxidised with twice its weight of 10% acid in 30 min., whilst orpimcnt requires 40% acid for 15 min. In the case of arsenical pyrites, about 16% of the arsenic is not attacked, and some oxygen is used in oxidising the iron. The amount of nitric acid required is in every case less than the amount that would theoretically be needed