f elevation
of the water over the end of the wire; and though a few minute bubbles of
gas were at the same time formed there, so as to prevent me from asserting
that the effect was unequivocally the same as that obtained by DAVY in the
metals, yet, according to my best judgement, it was partly, and I believe
principally, of that nature.

1609. I employed a voltaic battery of 100 pair of four-inch plates for
experiments of a similar nature with electrolytes. In these cases the
shell-lac was cupped, and the wire _b_ 0.2 of an inch in diameter.
Sometimes I used a positive amalgamated zinc wire in contact with dilute
sulphuric acid; at others, a negative copper wire in a solution of sulphate
of copper; but, because of the evolution of gas, the precipitation of
copper, &c., I was not able to obtain decided results. It is but right to
mention, that when I made use of mercury, endeavouring to repeat DAVY's
experiment, the battery of 100 pair was not sufficient to produce the
elevations[A].

[A] In the experiments at the Royal Institution, Sir H. Davy used, I
think, 500 or 600 pairs of plates. Those at the London Institution
were made with the apparatus of Mr. Pepys (consisting of an enormous
single pair of plates), described in the Philosophical Transactions
for 1832, p. 187.

1610. The latter experiments (1609.) may therefore be considered as failing
to give the hoped-for proof, but I have much confidence in the former
(1605. 1608.), and in the considerations (1603.) connected with them. If I
have rightly viewed them, and we may be allowed to compare the currents at
points and surfaces in such extremely different bodies as air and the
metals, and admit that they are effects of the _same_ kind, differing only
in degree and in proportion to the insulating or conducting power of the
dielectric used, what great additional argument we obtain in favour of that
theory, which in the phenomena of insulation and conduction also, as in
these, would link _the same_ apparently dissimilar substances together
(1336. 1561.); and how completely the general view, which refers all the
phenomena to the direct action of the molecules of matter, seems to embrace
the various isolated phenomena as they successively come under
consideration!

* * * * *

1611. The connection of this convective or carrying effect, which depends
upon a certain degree of insulation, with conduction; i.e. the occurrence
of bo