uantity_, and the same with
the volume of hydrogen evolved in the volta-electrometer, showing that in
all the vessels the current had decomposed an equal quantity of water. In
this trying case, therefore, the _chemical action of electricity_ proved to
be _perfectly definite_.

810. A similar experiment was made with muriatic acid diluted with its bulk
of water. The three positive electrodes were zinc, silver, and platina; the
first being able to separate and combine with the chlorine _without_ the
aid of the current; the second combining with the chlorine only after the
current had set it free; and the third rejecting almost the whole of it.
The three negative electrodes were, as before, platina plates fixed within
glass tubes. In this experiment, as in the former, the quantity of hydrogen
evolved at the _cathodes_ was the same for all, and the same as the
hydrogen evolved in the volta-electrometer. I have already given my reasons
for believing that in these experiments it is the muriatic acid which is
directly decomposed by the electricity (764.); and the results prove that
the quantities so decomposed are _perfectly definite_ and proportionate to
the quantity of electricity which has passed.

811. In this experiment the chloride of silver formed in the second basin
retarded the passage of the current of electricity, by virtue of the law of
conduction before described (394.), so that it had to be cleaned off four
or five times during the course of the experiment; but this caused no
difference between the results of that vessel and the others.

812. Charcoal was used as the positive electrode in both sulphuric and
muriatic acids (808. 810.); but this change produced no variation of the
results. A zinc positive electrode, in sulphate of soda or solution of
common salt, gave the same constancy of operation.

813. Experiments of a similar kind were then made with bodies altogether in
a different state, i.e. with _fused_ chlorides, iodides, &c. I have already
described an experiment with fused chloride of silver, in which the
electrodes were of metallic silver, the one rendered negative becoming
increased and lengthened by the addition of metal, whilst the other was
dissolved and eaten away by its abstraction. This experiment was repeated,
two weighed pieces of silver wire being used as the electrodes, and a
volta-electrometer included in the circuit. Great care was taken to
withdraw the negative electrodes so regularly a