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
