ric,
and muriatic. The sulphuric acid was strong oil of vitriol; one cubical
inch of it was equivalent to 486 grains of marble. The nitric acid was very
nearly pure; one cubical inch dissolved 150 grains of marble. The muriatic
acid was also nearly pure, and one cubical inch dissolved 108 grains of
marble. These were always mixed with water by volumes, the standard of
volume being a cubical inch.

1128. An acid was prepared consisting of 200 parts water, 4-1/2 parts
sulphuric acid, and 4 parts nitric acid; and with this both my trough
containing forty pairs of three-inch plates, and four porcelain troughs,
arranged in succession, each containing ten pairs of plates with double
coppers four inches square, were charged. These two batteries were then
used in succession, and the action of each was allowed to continue for
twenty or thirty minutes, until the charge was nearly exhausted, the
connexion with the volta-electrometer being carefully preserved during the
whole time, and the acid in the troughs occasionally mixed together. In
this way the former trough acted so well, that for each equivalent of water
decomposed in the volta-electrometer only from 2 to 2.5 equivalents of zinc
were dissolved from each plate. In four experiments the average was 2.21
equivalents for each plate, or 88.4 for the whole battery. In the
experiments with the porcelain troughs, the equivalents of consumption at
each plate were 3.51, or 141.6 for the whole battery. In a perfect voltaic
battery of forty pairs of plates (991. 1001.) the consumption would have
been one equivalent for each zinc plate, or forty for the whole.

1129. Similar experiments were made with two voltaic batteries, one
containing twenty pairs of four-inch plates, arranged as I have described
(1124.), and the other twenty pairs of four-inch plates in porcelain
troughs. The average of five experiments with the former was a consumption
of 3.7 equivalents of zinc from each plate, or 74 from the whole: the
average of three experiments with the latter was 5.5 equivalents from each
plate, or 110 from the whole: to obtain this conclusion two experiments
were struck out, which were much against the porcelain troughs, and in
which some unknown deteriorating influence was supposed to be accidentally
active. In all the experiments, care was taken not to compare _new_ and
_old_ plates together, as that would have introduced serious errors into
the conclusions (1146.).

1130. When ten pa