38 REPORT — 1839. 



minus that of oxygen for azote*; nitric acid being much more readily 

 decomposed than sulphate of copper, resistance is lessened, and the 

 power increased ; and no hydrogen being evolved from the negative 

 metal, there is no precipitation upon it, and consequently no counter- 

 action. 



" I need scarcely add a word as to the importance of improvements 

 of this description in the voltaic battery : this valuable instrument of 

 chemical research is thus made portable, and by increased power in 

 diminished space, its adaptation to mechanical, and especially to loco- 

 motive purposes, becomes more feasible." 



Notices of Experiments on the deposition of Metals by Voltaic Action. 

 By Thomas Spencer, Esq. {Liverpool.) 



Among other experiments made by the author to ascertain the truth 

 of an opinion he had been previously induced to entertain, namely, 

 that if two fluids of different densities were placed as much as possible 

 in mechanical contiguity, that is, without the fluids being suffered to 

 intermingle, an electro-chemical current would be eliminated by the 

 disturbance of the electrical equilibrium, the following was described : 



He took a very tall tubular vessel and half-filled it with a solution 

 of nitrate of silver ; he then added distilled water in the most careful 

 manner with a pipette, allowing the drops to run down the side of 

 the vessel until he had nearly filled it. By proceeding thus, he was 

 enabled to keep the fluids from intermingling, their density being 

 different. When thus filled, a narrow slip of silver was inserted, long 

 enough to go through both strata of the fluid. The whole was placed 

 in a dark situation, and suffered to remain for a few hours, when evi- 

 dent marks of voltaic action began to manifest themselves. In the 

 course of a few days beautiful metallic crystals had formed on that por- 

 tion of the silver that was immersed in the solution of the nitrate ; that 

 part of the slip situated where the two fluids met, was left to about one 

 eighth of an inch untouched, while that end placed in the acidulated 

 water became oxidized in the inverse ratio of the deposition on the 

 opposite end. 



A series of slips of different metals, including zinc, were subjected 

 to similar treatment in their respective solutions, and with like results. 



From these experiments Mr. Spencer was led to conclude, that the 

 appearances that are sometimes observed in the mines, and which have 

 been attributed to electrical action, might be simply and satisfactorily 

 explained without supposing the presence of two dissimilar metals, or 

 even metalliferous bodies, as the water found in the mines, and con- 

 taining salts of the different metals in solution, would, in their action 

 on a single metalliferous substance, generate electricity sufficient to 

 account for the deposition of crystals of the pure metal so frequently 

 found on the poorer copper ores. 



* I have thrown out of the case the resistance to decomposition of the electrolyte in 

 contact with the zinc, as common to the three combinations. 



