a continuous current through the apparatus, and we may regard the
part where the acid is acting on the plates and the part where the
current is acting upon the water as the reciprocals of each other. In
both parts we have the two conditions, _inseparable in such bodies as
these_: the passing of a current, and decomposition. In the one case we
have decomposition associated with a current; in the other, a current
followed by decomposition.

Let us apply this in support of my surmise respecting the enormous
electric power of each particle or atom of matter.

Two wires, one of platina, and one of zinc, each one-eighteenth of an
inch in diameter, placed five-sixteenths of an inch apart, and immersed
to the depth of five-eighths of an inch in acid, consisting of one drop
of oil of vitriol and four ounces of distilled water at a temperature of
about 60 deg. Fahrenheit, and connected at the other ends by a copper wire
eighteen feet long, and one-eighteenth of an inch in thickness, yielded
as much electricity in little more than three seconds of time as a
Leyden battery charged by thirty turns of a very large and powerful
plate electric machine in full action. This quantity, although
sufficient if passed at once through the head of a rat or cat to have
killed it, as by a flash of lightning, was evolved by the mutual action
of so small a portion of the zinc wire and water in contact with it that
the loss of weight by either would be inappreciable; and as to the water
which could be decomposed by that current, it must have been insensible
in quantity, for no trace of hydrogen appeared upon the surface of the
platina during these three seconds. It would appear that 800,000 such
charges of the Leyden battery would be necessary to decompose a single
grain of water; or, if I am right, to equal the quantity of electricity
which is naturally associated with the elements of that grain of water,
endowing them with their mutual chemical affinity.

This theory of the definite evolution and the equivalent definite action
of electricity beautifully harmonises the associated theories of
definite proportions and electro-chemical affinity.

According to it, the equivalent weights of bodies are simply those
quantities of them which contain equal quantities of electricity, or
have naturally equal electric powers, it being the electricity which
_determines_ the equivalent number, _because_ it determines the
combining force. Or, if we adopt the a