by Compounds for Decomposition. 847 
of time in each, we shall find that in the Grove’s three or four 
times as much zinc has been dissolved as in the other. What, 
then, is the fact ?—that in the Grove’s pair the electricity passes 
with three or four times the rapidity it does in the pair with one 
fluid ; and the only difference between the pairs being, that in 
the latter water is decomposed, and in the former nitric acid, it 
follows that an equivalent of nitric acid is decomposed three or 
four times more quickly than one of water under like circumstances. 
To proceed more exactly. I puta porous vessel into a gutta- 
percha trough, and filled the latter with sulphuric acid, sp. gr. 
1-1. In the sulphuric acid I placed an amalgamated zinc plate, 
and in the porous cell a platina plate surrounded by several solu- 
tions in succession, such as nitric acid, solution of sulphate of 
copper, solution of nitrate of silver, &e. These solutions in the 
porous cell suffered decomposition when the zinc and platina 
plates were joined externally, the base being thrown down on 
the platina plate. There was therefore no polarization; and I 
introduced a sufficient resistance externally to render the resist- 
ances of the solutions which were decomposed comparatively 
nothing. I had therefore several combinations similar in every 
way, except in the fluid that surrounded the negative or platina 
plate ; and the only difference in the chemical actions of the 
pairs was in the decompositions which occurred. If, therefore, 
on transmitting the current produced by joining the metals 
through a galvanometer, there was any difference in the amount 
of electricity, this difference must have been occasioned by the 
decomposition alone. 
Sulphuric acid surrounding the porous cell, and amalgamated 
zinc in the acid, I put the platina plate in the porous cell and 
filled it with nitric acid, thus forming a Grove’s pair. When the 
metals were joined, a certain resistance and galvanometer being 
included in the circuit, the needle of the galvanometer stood at 
103 degrees of the scale. 
I now removed the nitric acid and substituted solution of sul- 
phate of copper, thus forming a Daniell’s pair: with the same 
resistance and arrangement as in the former experiment, the 
needle stood at 54 degrees. 
With solution of nitrate of silver in place of the sulphate of 
copper, the needle stood at 9. 
With solution of iodic acid, the needle stood at 10; with aci- 
dulated water, at 32. 
Now each of these numbers represents the quantity of elec- 
tricity passing in a given time, or its rapidity; and as the pairs 
only differ from each other in the decomposition cell, it follows 
that an equivalent of each compound is decomposed in a different 
period of time. The numbers likewise represent the electromo- 
