the
ground, conduct the electricities into the earth, and thus answer the
purpose?

MRS. B.

It would answer the purpose of carrying off the electricity, I admit;
but recollect, that though it is necessary to find a vent for the
electricity, yet we must not lose it, since it is the power which we are
endeavouring to obtain. Instead, therefore, of conducting it into the
ground, let us make the wires, from either plate, meet: the two
electricities will thus be brought together, and will combine and
neutralize each other; and as long as this communication continues, the
two plates having a vent for their respective electricities, the action
of the acid will go on freely and uninterruptedly.

EMILY.

That is very clear, so far as two plates only are concerned; but I
cannot say I understand how the energy of the succession of plates, or
rather pairs of plates, of which the Galvanic trough is composed, is
propagated and accumulated throughout a battery?

MRS. B.

In order to shew you how the intensity of the electricity is increased
by increasing the number of plates, we will examine the action of four
plates; if you understand these, you will readily comprehend that of any
number whatever. In this figure (PLATE VI. Fig. 4.), you will observe
that the two central plates are united; they are soldered together, (as
we observed in describing the Voltaic trough,) so as to form but one
plate which offers two different surfaces, the one of copper, the other
of zinc.

Now you recollect that, in explaining the action of two plates, we
supposed that a quantity of electricity was evolved from the surface of
the first zinc plate, in consequence of the action of the acid, and was
conveyed by the interposed fluid to the copper plate, No. 2, which thus
became positive. This copper plate communicates its electricity to the
contiguous zinc plate, No. 3, in which, consequently, some accumulation
of electricity takes place. When, therefore, the fluid in the next cell
acts upon the zinc plate, electricity is extricated from it in larger
quantity, and in a more concentrated form, than before. This
concentrated electricity is again conveyed by the fluid to the next pair
of plates, No. 4 and 5, when it is farther increased by the action of
the fluid in the third cell, and so on, to any number of plates of which
the battery may consist; so that the electrical energy will continue to
accumulate in proportion to the number of double plates