SE = 
Voltaic Electricity on Alcohol, &c. : 337 
necessarily conducted into it, by a train of investigation which, 
in its origin, had no reference to this particular part of the in- 
quiry. 
From the important aid which Mr Farapay’s principle of the 
direct connection between the quantity and chemical action of 
an electric current, is capable, if well founded, of affording, in 
determining such questions as I had in view, this principle was, 
of couyse, one of my chief subjects of examination; and I found 
it necessary to endeavour to satisfy myself, in so far as regarded 
solutions, how far the evidence was sufficient to establish that 
the chemical action of an electric stream is proportional to the 
absolute quantity of transmitted electricity, and that a given 
quantity of electricity will decompose a chemical equivalent of 
the substances on which it acts. 
For the purpose of bringing these principles to the test of ex- 
periment, Mr Farapay has employed an arrangement to which 
he gives the name of the Volta Electrometer, of which there are 
several modifications, but all of them depending on the principle 
that the hydrogen and oxygen evolved from water under decom- 
position by a given electric current, are collected, and measured, 
and compared with the same or different elements, as the case may 
be, separated from the same or a different substance, which is un- 
der decomposition by the same electric stream.* Now, I have 
had ample opportunities of confirming experimentally the truth of 
the above law, in so far as regards water, and have no doubt what- 
ever that the same current of electricity will always decompose the 
same absolute quantity of water, when it exerts its decomposing 
* It is only doing justice to MM. Gay Lussac and Tuenarp to remember, 
that they long ago employed the quantity of the gases evolved by water under the 
agency of the voltaic current as a measure of its chemical effects (Recherch. Phys. 
Chim., Part i.) They did not, however, compare this quantity with other effects 
produced by the same current at the same time. 
