- ~ oe - : | = & aS ad 
. A ; : z . 
ie * ah ‘i * 
a ae Elecirography. 5 as 
ing granulations over its whole surface, —_ inequality —_ 
* 3 “ing to a similar one on the membrane. 
; - » These facts may be important in the sedeceal use of Oi 
oy There success depends on the beauty of the result. 
Mr. Spencer remarks, that in these experiments the zinc en 
ps a be amalgamated, notwithstanding the great advantage of 
aot of treating zinc in other Voltaic arrangements. Our 
we nce, on the other hand, has shewn us that there are advan- 
tages in adopting this method, and the results which we have 
obtained with amalgamated zinc, have been very goo 
The phenomena attending this process are interedishgi It bi 
been long known that in the electrolysis of a metallic salt, both 
the salt mid the water of the solution are decomposed. In this 
case the sulphate of copper is at first resolved into sulphuric acid 
and oxide of copper, and the water also into its elements. 
The sulphuric acid being electro-negative goes over to the zine- 
ode, whither the oxygen of the decomposed water has also gone. 
Here the oxygen unites with the zinc to form the oxide of that 
metal, which is instantly dissolved by the free sulphuric acid, 
forming sulphate of zinc. But the hydrogen liberated from the de- 
composed water all goes to the plata e, where; finding the oxide 
of copper, it unites with its oxygen to form water, and the metal- 
lic copper is deposited, according to its own laws of crystallization, 
on the nearest metallic surface in the Voltaic circuits. Hence the 
art which forms the subject of this article. It must also be re- 
membered that the same phenomena attend the zincode of this 
series that we have described as belonging to the copper or plati- 
node, namely, water is there decomposed, the oxygen forms 0% 
ide of zinc, and the hydrogen goes to reduce the oxide of cop 
per, unless indeed, there is an excess of sulphuric acid in the 
zinc cell, in which case, free hydrogen will be evolved from 
that cell. The deposit of metallic copper is an exact equivalent 
for the oxidation of the zinc. Indeed no deposit can take place’ 
until the zinc is oxidized, and hence the necessity of a free aci 
or saline fluid in the zinc cell, to commence the decomposition. 
Much light has been duben by these experiments and those 0 
Mr. Fox on the mode in which metallic deposits occur in nature. 
But at this time we can only mention the subject; to treat of it 
would require more space than we can at present command; we 
postpone it therefore to some other occasion. ~ B. S., Jz 
Yale College Laboratory, Dec. 23d, 1840. 
