with a reverse current passing through the cell. T h e two values agree very well, showing the reversibility of the cells. [This is a very surprising resnlt for copper in cupric chloride solutions, since the electrode is not reversible.]
1v. D . R. On the theory of the electrolytic solution-pressure. K . A.Lehfedtit. Phil. iJfag.[j]48, $30 (1899) ; Zeit. plzys. Cheii~.32, 360 (1900).-Starting from the assumption of an electrical double layer at the contact between metal and solution, the author * ’ arrives at the conclusion that, in order to produce the solution-pressure attributed to zinc, 1 . 2 7 grams of the metal would have to pass into t h e ionic form per square centimeter immersed, which is obviously not t h e case. ’ ’ lV. 11. R. Note on the theory of solution-pressure. S. /Z. dJlil?iei*. Phil. 1JIag. [j] author gives a new deduction of the S e r n s t forniiila for the difference of potential between a metal and solution. Ilis proof as t o t h e effect of other substances in the solution is sound only so long a s we make t h e assumption that the solution-pressure is not unchanged by such addition. Lehfeldt’s difficulty in regard to the solution-pressure (preceding review) is dismissed with the explanation of “ variation from the gas laws.” IV, D.6. 49, 417 ( 1 9 0 0 ) . - T h e
Electromotive behavior of substances with several oxidation stages, I. A’. Luther nizd U . X. lt’ifsoir. ZeiL. p h j ~ . ~Cheiit. . 34, ,491 ( / 9 0 0 ) .- T h e author shows that it is possible to deduce the potential difference Cu I CuSO, from measurements of Cu j CuCl in KC1 and P t 1 CuCl in CuSOI - KC1. T h e calculated value was practically identical with that found experinlentally. I t was also sliown that the concentration of copper as ion in a copper sulphate solution is not changed by the addition of potassium chloride or bromide. M , .D. 1;. Novel thermo-electric phenomena. W. F. Bnrrett. Phil. lag. 49, 3joy (1900).-- The large electrical resistance of a sample of nickel steel with j percent of manganese. led the author to determine its thernio-electric properties. When coupled with a wire of pure iron, the therrno-electric force rose with t h e temperature to about 300°, when it became almost exactly $teady u p to L O O O ~ . Experinients with the alloy were made coupled with other metals. Other iron alloys were tried and, in general. it was found that t h e indications of the temperature were not always the same, hut depended on lyhether the couple was being heated or cooled. H . T. 1z. On some effects of twist on the thermo-electric qualities of iron. K. Tssiii-ntn. [j]50, 223 ( 1 9 0 0 ) . - The author draws the folloiving conclusions : That in soft iron of certain kinds there exists t h e phenomenon of thermoelectric hysteresis with respect to twist (at least when cornbined with longitudinal tension) : That other things being equal, the hysteresis is reversed at a certain twist : T h a t mechanical agitation has its o\vn effects. which are reversed as the hysteresis is reversed. ?K ZI.6.
Phil..lZug.
The passive state in metals. 11’. Hittoi;f. Z e i f . p h j ~ .Chem 34, 383 (1900).- Passive iron gradually becomes active and the same is true of nickel
and cobalt. This leads the author to the assumption that passivity is a sort of electrical hysteresis, the elenlent being brought into t h e passive state by rlectrical stress in presence of certain anions, The author rejects the hypothesis of a film of oxide and brings the phenorrienon i n line with the behavior of lead and silver in certain solutions i n which they form peroxides. The article contains a number of most interesting ohservatioris on the conditions governing the pas14: D. L?. sivity of iron, nickel. and chromium. The magnetic properties of the alloys of iron and aluminium. .C. I f ' . Richnidsox. Phil. ;Vag. 49, i z i [ iyoo). -The author investigates the alloys of aluminiuni and iron in a way similar to the well known e s p e r i n ~ e n t of s Hopkinson on alloys of iron and nickel. T h e alloys behave magnetically as though they consisted of two distinct media superposed. A numher of €3 and H curves are given as well as R and T curves, and B and p curves. The experiniei?ts were carri.ed over a range of teniperature extending from about ~- 83' to gtm'.
N.T, E . Elert v0ly.r is a 12 d Elrci'i+oiyfic D issocia t io?/ Electrolysis of the alkali salts of organic acids, J . Pefrv-se.n. %if. fl/zy.c. cheiii. 33, 9 9 , z p j , 698 ( r y o o ) .- T h e author has electrolyzed solutions of the potassium salts of formic, acetic, propionic, butyric. isobutyric. isovalerianic. valerianic, trimethyl acetic, capronic, oxalic, malonic, succinic, niethyl malonic. pyrotartaric. ethyl malonic, and sebacic acids. The author worked with large quantities of niaterial. passing a current of about one-half ampere. in one case, for nearly seven hundred hours. The gases and liquids formed were all identified and determilied q~iantitativelyas far as possible. The conclusions drawn by the author are hardly cominensurate with the labor expended. R'. I:.
n.
The electrolytic preparation of benzidine. TI'. Lob. ,BPI.. he,^. CLT.fie.!-lin, 33, 2329 ( 1 9 0 0 ) . - I n the reduction of iiitroheiizene either in alkaliiie or i n acid solation, the numher of intermediate products, under ordinary circumstances. is great and the reduction cannot he stopped at the \\ished-for product. T h e most favorable conditions for the formation of benzidine are the primary formation of azobenzene in acid solution, or of azoxyhenzene i n alkaline solution, and the subsequent reduction of the compounde to l ~ e t ~ z i d i nin e an acid electrolyte. The reductions took place i n a porous cnp, the bottom of which, filled with mercury. served as the cathode. Vigorous stirring was found to he of service. In the reduction of azohenzene to benzidine, perfect absorption of hydrogen takes place. Eighty percent of henzidine was obtained. The yield of diphenyline was at the highest 7 percent. I n the direct reduction of ~ ~ i t r o henzsne iii ail alcoholic solutiorl of sodium acetate or socliurn hydroxide, and the subsequent reduction of the same misture in acid solution. a yield of 76-So percent of benzidine was obtained. I n aqueous solution the reduction of nitroheiizene to azoxybenzene, and the reduction of this compound to benzidine was accomplished. The latter takes place i n alcoholic solution of sulphuric acid. c.G. L . I{ '.
