298 Intelligence and Miscellaneous Articles. 



A rod of zinc, under similar circumstances, covers itself with gray 

 granules of metallic zinc, especially at its lower end. In this case 

 also the zinc is dissolved at the point of contact of the fluids. 



Cadmium behaves in a similar manner in the solution of its 

 nitrate; the reduced metal is more pulverulent, and therefore much 

 more readily oxidized in the air than the reduced zinc. 



Lead, in a solution of neutral nitrate or acetate of lead, furnishes 

 small sliining crystals of lead. 



Bismuth precipitates the metal from a solution of protochloride of 

 bismuth, if the latter has been overlaid first with muriatic acid, and 

 afterwards with water. 



On silver, immersed in a concentrated solution of nitrate of silver 

 overlaid with water, metallic silver is deposited in a dendritic form, 

 always originating from a few scattered points of the surface of the 

 silver. — Atm. der Chein. und Pharm., Ixxxv. p. 253. 



ON THE DECOMPOSITION OF WATER BY THE PILE, BY J. JAMIN. 



M. Foucault has just published a note in which he shows that two 

 voltameters traversed by the same current disengage different quan- 

 tities of gas, if one contain acidulated water, with electrodes of pla- 

 tinum wire, and the other only pure water, with plates of a certain 

 size for electrodes. 



M. Foucault explains this phsenomenon by supposing that fluids 

 transmit electricity in two ways : by physical conductibility, which 

 is effected without decomposition ; and by chemical conductibility, 

 which causes a separation of their elements. M. Foucault collected 

 the gases in the same receiver, and did not endeavour to ascertain 

 whether the passage of the current gave rise to any new chemical 

 compound. The author has been occupied for several months in 

 similar researches, and had ascertained the fact which M. Foucault 

 has published. He now confirms it, but adds some experiments 

 which prevent his admitting the theoretical consequences of M. 

 Foucault. 



In attentively studying the decomposition of water, it is evident 

 the separation of its elements does not take place with the simplicity 

 hitherto supposed. The double volume of hydrogen is scarcely ever 

 obtained, and predominating quantities of either gas may be produced 

 by alteration of circumstances, and especially by changing the extent 

 of one of the electrodes. 



Employing as a positive electrode a Wollaston wire, and as a ne- 

 gative a plate of 15 square centimetres, the author obtained five cubic 

 centimetres of hydrogen and nine of oxygen, being in a proportion 

 of 0'55 instead of 2 to 1. By changing the direction of the current 

 so as to reverse the electrodes, and waiting for some hours to avoid 

 errors of polarization, the volume of hydrogen collected was to that 

 of oxygen as 9'3 to I'O instead of 2. These experiments, frequently 

 repeated, did not always furnish equally decisive results, but they 

 had always the same tendency ; showing that electrodes with a 

 large surface, whether positive or negative, disengage less gas than 

 fine slender wires employed as the opposite electrodes in the same 

 voltameters. 



