Above 0-01A7 a strong medium effect of the undis
F. U. (c) Change of equilibrium by adsorption
H a h n and R. K l o c k m a n n (Naturwiss., 1932, 20, 331).—The p n of an JV/2000-pyridino solution is 7-14;
when hydrated A1203 is suspended in the pyridine solution the p n rises to 8-8, and with activated char
coal suspended in the pyridine the p n rises to 9-2.
W. R. A.
Direct measurement of primary, secondary, and total medium effects of acetic acid. B. B.
O w e n (J. Amer. Chem. Soc., 1932, 54, 175S—1769;
cf. A., 1931, 308).—Primary, secondary, and total medium effects are defined and their calculation from e.m.f. data is described. From e.m.f. data for HC1 solutions containing AcOH the total medium effect of AcOII has been calc. Approx. equations connecting the primary medium effects of a particular medium on two similar electrolytes have been obtained.
G. M. M. (c)
¡(-Potential for a double layer of anomalous viscosity. H. R e i c h a r d t (Z. physikal. Chem., 1932, 159, 417—427 ; cf. A., 1931, 795).—Equations have been derived for the ¡(-potential, and the thickness of the doublo layer and stratum of anomalous viscosity when a certain min. shearing stress, which diminishes continually as the distance from the wall increases, must bo applied before any flow occurs in the double layer. Variation of ¡(-potential with rate of flow and Kohler’s results (this vol., 17) are accounted
for. R-
C-Theory of hydrogen overvoltage. A. Fr u m e iN (Z. physikal. Chem., 1932,160, 116—118).—By treat
ing the electrode charged with H as an acid in Brdn- sted’s sense the relation between current strength and H2 overvoltage is shown to reduce to an equation of the same form as that relating the affinity const, of a weak acid or base to its catalytic activity. R. Q.
Mechanism of overvoltage and its relation to the combination of hydrogen atoms at metal electrodes. J. A. V. B u t l e r (Trans. Faraday Soc., 1932, 28, 379—382; cf. A., 1924, ii, 598; this vol.,
G E N E R A L , P H Y S IC A L , A N D IN O R G A N IC C H E M IS T R Y . 7 0 1
25).—In confirmation of the equation developed, the overvoltage at a Pt cathode varies linearly with c.d. between 10_G and 10~7 amp. per sq. cm. Tho slow decay of H2 overpotential at Hg in H2S04 per
sists after drastic treatment for removing traces of
alkali metals. J. G. A. G.
Improved commutator and some sources of error in commutator method for measurement of overvoltage. A. L. F e r g u s o n and G. M. C h e n (J. Physical Chem., 1932, 36, 1156—1165).—A commutator is described for measuring charge or discharge potentials within 0-0003 sec. of the begin
ning or end of the charge and discharge intervals for the electrodes either combined or separately.
R. H. C. (c) Measurement of polarisation by direct and commutator methods. A. L. F e r g u s o n and G. M.
C h e n (J. Physical Chem., 1932, 36, 1166—1177).—
Potentials were measured within 0-0005 sec. from end of charge or beginning of discharge. Anode, cathode, and total potentials were measured prac
tically simultaneously during the charge and discharge intervals without stopping the interrupter. For platinised electrodes in 2A’ -H2S04 there is no surface resistance of any kind for c.d. of 0-0038—0-150 amp.
With smooth Pt electrodes the decrease in discharge potential is so rapid that satisfactory results cannot be obtained with the interrupter-potentiometer
system. R. H. C. (c)
Electrolytic deposition of polonium on metals.
M. H a i s s i n s k y (Oompt. rend., 1932, 194, 1917—
1919; cf. this vol., 236).— The negative crit.
potentials in alkaline solution of the Po deposit on cathodes of Pt, Au, Au (beaten), Cu, Ag, Sn, Ni, indicate that the Po is hydrolysed. and, in the form of Po03", acts as a depolariser. In an acid medium (0-23A-HNO:l) with Ag cathode the crit. potential
is +0-36 volt, C. A. S.
Fortuitous empirical relationships in chemical kinetics. D. T. L e w i s and L. J. H u d l e s t o n
(J.C.S., 1932, 1398— 1400).—-The simple relation found between E and log B in the equation of Arr
henius for the variation of the velocity coelf. of a reaction with temp, is a necessary consequence of considering only those reactions for which log k at the mean temp, of measurement, T , does not vary greatly, and has no theoretical significance. F. L. U.
Kinetics of adsorption in relation to reaction velocity. F. H . C o n s t a b l e (Trans. Faraday Soc., 1932, 28, 227—228).—See A., 1928, 718.
J. G. A. G.
Measurements of flame velocities. A. B e c k e r
and K. Vogt (Z. Physik, 1932, 75, S04—80S).—A precision method, using rotating mirrors, is described.
A. B. D. C.
Kinetics of gas explosions. II. Thermal reaction between ozone and hydrogen bromide.
B. L e w i s and W. F e i t k n e c h t (J. Amer. Chem. Soc., 1932, 54, 1784—1792).—Reaction occurs through reaction chains which start on the wall and proceed rapidly into the gas phase, probably being propagated hy the OH radical. The rate of the non-explosive reaction is proportional to the initial concns. of HBr
and 03, and the temp, coeff. between —104° and 77°
is 1-79, giving 3800 g.-cal. for the heat of activation.
He, A, H2, and 02 have a retarding action, which increases in this order, and increase the explosion limit by an amount which increases in the reverse order. Explosion may occur at —104° under 24 mm.
total pressure. ■ C. W. (c)
Kinetics of reaction EL, (gas)^=^2H (dissolved in palladium). C. W a g n e r (Z. physikal. Chem., 1932, 159, 459—469).—Under such conditions that the changes occurring at the surface are sufficiently slow compared with diffusion within the Pd wire to determine the rate of the process as a whole, the rate of reaction may, depending on the previous thermal treatment of the Pd, be represented by d c / d t = k ' ^ / p — k c = k ( c e—c), or d c j d t = k 1p —k,,ci = k 2(ce2—c i ),
or some combination of these, where c is the concn. of H within the Pd at time f and ce the equilibrium concn. for the gas pressure p , and k \ k, k v and k 2
are consts. If the slow process were H (adsorbed) ===
H (dissolved) the first equation would result, whilst if it were II2 (adsorbed) =^=a=2H (dissolved in Pd) or H2 (adsorbed) 2H (adsorbed) the second equation would be valid. The rate of absorption of Oa by Ag foil (A., 1926, 1089) seems to be determined by reactions at the interface, rather than by diffusion.
R. C.
Explosive combination of hydrogen and oxygen. Function of walls in gaseous reactions.
H. W. T h o m p s o n (Trans. Faraday Soc., 1932, 28, 299—308).—The lower crit. explosion pressures of the gas mixtures were determined at room temp, by tho spark method (cf. A., 1931, 174). The crit. partial pressure of H2 varies greatly,1! but that of 02 is approx. const, within a wide range of composition of H„-Oo mixtures. The addition of He, A, N„, CO,,, S02, ~CH2(OEt)2, COMe2, N20, CC14, and CHCi3 depresses, in order of increasing effect, the partial pressure of H2 plus 02 required for explosion. 02 has the most marked “ inert gas” effect. Variation of diameter of the reaction vessel has approx. the effect predicted by the equation (A., 1931, 1014).
J. G. A. G.
Oxidation of phosphorus vapour at low pres
sures. H. W. M e l v i l l e (Trans. Faraday Soc., 1932, 28, 308—315).—Theory is developed and correlated with existing data. The equation (A., 1931, 1014) is corrected by replacing I ) by D l . Whilst PH3 raises the lower crit. explosion pressure, p , of P4- 0 2 mixtures, small concns. of 0 3 decrease p much more than is required by a normal diffusion effect. P vapour diminishes p for PH3- 0 2 mixtures. The effects of surfaces are examined. J. G. A. G.
Energy exchange in unimolecular reactions.
I. Decomposition of mixtures of dimethyl and diethyl ether. E. W. R. S t e a c i e (J. Physical Chem., 1932, 36, 1562—1569).—See this vol., 576.
Influence of hydrogen on the pyrolysis of ethane and ethylene near 600°. I. M. W.
T r a v e r s and L. E. H o c k i n (Proc. Roy. Soc., 1932, A, 136, 1—27).—C2H6 or C2H0-C2H4-H 2 mixtures when heated to 600° in closed tubes give rise to 3 reactions : (1) the reversible C2HG-C2H4-H 2 reaction which is independent of the other two and of the .
7 0 2 B R IT IS H C H E M IC A L A B S T R A C T S .— A .
h 2 concn. except in so far as H2 is a reactant; (2) the formation of C6Hfi and CH4 from 02HG alone;
and (3) the formation of CGHG and CH4 from C2HG and C2H4. The formation of CGHG from C2HG is endothermic and of zero order, whilst from C2H4 it is exothermic and the rate of formation follows a
complex expression. L. L. B.
Homogeneous first order gas reactions. II.
Decomposition of butylidene diacetate and ethyl- idene dipropionate. C . C . C o f f i n (Canad. J. Res., 1932, 6, 417—427).—The thermal decomps, of butyl
idene diacetate and ethylidene dipropionato, like that of ethylidene diacetate, are homogeneous unimol. reactions, proceeding to completion and each yielding an anhydride and an aldehyde. Measure
ments were made at 2 11—265°, and the velocity coeffs.
of the three esters in the above order are given by log, ¿=24-20—32,900/RT, log, ¿= 2 3-9 6 -32,900/AT, and log, ¿=23-74—32,900¡ R T , respectively. The energies of activation are thus equal, but the velocities different. It is suggested that the former is the min. energy that a linking must acquire to enable the mol. to divide, and that this is unaffected by structural changes in other parts of the mol. The velocity, however, dopends on the no. of degrees of freedom capable of contributing to this energy and is affected by changes in other parts of the mol., although it is believed that large mols. are divided into sections between which there is no energy
exchange. A. G.
Nitric acid as an oxidising agent. I. Mechan
ism of oxidation of hydrochloric acid. S. S e l t
z e r (Z. physikal. Chem., 1932, 159, 428—435).—The reaction of HN03 with a large excess of HC1 in aq.
solution at 60° follows the unimol. law, with a temp, coeff. of 2-45, and is represented quantitatively by the equation 3HC1+HN03=N 0C 1+C12+ 2H 20.
Ag2S04 has considerable catalytic action, but chlorides
seem to have no effect. R. C.
Neutral salt e fleet of the ferric-iodide ionic reaction. III. Influence of non-electrolytes on velocity of reaction. A. v o n K i s s [with P. V a s s ] (Z.
anorg. Chem., 1932, 206,196—208; cf. A., 1930,1256;
1931, S02).—The reaction is still unimol. with respect to Fe’" and bimol. with respect to I' in presence of MeOH, EtOH, Pr°OH, glycerol, COMe2, sucrose, and CO(NH2)2. Of these only CO(NH2)2 is known to form complexes with Fe” '. If KI is partly re
placed by KC1 for const. [Fe’” ], or FeCl3 by A1C13 for const. [I'], in presence of CO(NH2)2 or EtOH, the Bronsted-Debye-Hiickel rule for neutral salt action still holds. Grube and Schmid’s rule relating to the action of the medium (A., 1926, 474) is also strictly
followed. M. S. B.
Kinetics of the oxidation of oxalic acid by chlorine. R. O. G r i f f i t h and A. M c K e o w n (Trans.
Faraday Soe., 1932, 28, 518—522; cf. this vol., 344).—The data obtained at 10°, 15°, and 20° with JR/20—M/80-H2C2O4 in 0-25-0-7Ar-HCl plus 0—
l-9Ar-KCl and JR/100—JR/150-CU are consistent with the rate-determining reaction H0C1+HC204'— >- H20+2C0.,-r-Cr. The temp, coeff. of this reaction and of the initial val. of the unimol. coeff. with respect
to titratable CL is 2-49 and 4-0, respectively (cf. A.,
1930, 175). “ J. G. A. G.
Cellulose-cuprammonium solution. IV. Re
action heat and velocity between cellulose and cuprammonium solution. N. Isim (J. Cellulose Inst. Tokyo, 1932, 8, 44—48).—The lack of data as to the velocity of reaction between cellulose and alkaline Cu solutions is due to the difficulty of de
termining analytically the amounts of Cu combined with the dispersed cellulose. The heat generated when cellulose dissolves in cuprammonium solution indicates the progress of the reaction. The heat of reaction is independent of any variation in the structural properties of cellulose. The reaction is intramicellar, but is probably not confined to the surface of the micelle. V. E. Y.
Oxidation of cystine by iodine in aqueous medium. K. S h i n o h a r a (J. Biol. Chem., 1932, 96, 285—297).—Cystine, oxidised by the iodate method, reacts with more K I03 than is required for its oxid
ation to cysteine in proportion as the concn. of HC1 decreases. Measurement of the rate of consumption of I by cystine showed that cysteic acid is the final product; this acid was isolated in theoretical yield according to the reaction R'S‘S-R-}-5l2-t-6H20=
2RSO3H +10H I, and its properties were determined.
[Theory of oxidative processes. Imparity and radical chains in the reaction mechanism of organic and enzymic processes.] J. K e n n e e
(Ber., 1932, 65, [13], 705—710).—A reply to Haber and Willstatter (this vol., 352). H. W.
Open weighing of hygroscopic substances. J.
R e h n e r , jun. (Z. anal. Cliem., 1932, 88, 266—270).—
Mathematical expressions are derived for the rate of absorption of H20 from the air by Ca(N03),, CaCl2,
Mg(C104)2, and LiN03. A. R. P.
Rate of dissolution of zinc in acids. C. V . K i n g
and M. M. B r a v e r m a n (J. Amer. Chem. Soc., 1932, 54, 1744— 1757).—The effects of concn., a common ion, viscosity, rotation speed, and temp, on the rate show it to depend on a diffusion process. Whether ions other than H30 ‘ are active is undecided. Data are given for the dissolution of Mg, Cd, and CaC03
in HC1. H. A. B. (c)
Mechanism of molecular statistics of the reaction C uS04,5H20 = C uS04,H20 + 4H.0.
B. T o p l e y (Proe. Roy. Soc., 1932, A, 136, 413—
428).—The intermediate steps in the dehydration of CuS04,5H20 to the monohydrate, and the conditions governing the appearance of the trihydrate instead of the monohydrate as the product of the reaction in vac. are discussed. By means of a model, which takes account of the actual conditions in the reaction zone, a detailed statistical-mechanical interpretation of the relationships between the abs. reaction velocity and its temp, coeff. is attempted. L. L. B.
Chemical activity and particle size. II- Rate of dissolution with slow stirring of anhydrite and gypsum. P. S. R o l l e r (J. Physical Chem., 1932, 36, 1202—1231).—The relative ‘rates of dis
solution of powders consisting of particles of uniform diameter, D , varying from 1 to 250 g have been deter
G E N E R A L , P H Y S I C A L , A N D IN O R G A N IC C H E M IS T R Y . 7 0 3
mined at 20° for a fixed speed of stirring such that dissolution occurs from a settled sediment through which the solvent flows. For all sizes the rate of dissolution, v , is initially high, and falls in 2 min. to a low linear rate, hut starting from the dry powder there is a period of induction if D < 17 a. If D > 8 ¡a,
v increases proportionately to the surface exposed, but if D < 8[J. the increase is more rapid, which is attributed solely to the effect of edges and corners. Entangled air has no effect. The results lend no support to Nernst’s theory of heterogeneous reaction.
S. L. (c)