ction, the action of
presence, or by what learned name we choose. Give what name to it we
will, it is a manifestation of power which crosses our established laws
of combination at a very open angle of intersection. I think we may
find an analogy for it in electrical induction, the disturbance of the
equilibrium of the electricity of a body by the approach of a charged
body to it, without interchange of electrical conditions between the
two bodies. But an analogy is not an explanation, and why a few drops
of yeast should change a saccharine mixture to carbonic acid and
alcohol,--a little leaven leavening the whole lump,--not by combining
with it, but by setting a movement at work, we not only cannot explain,
but the fact is such an exception to the recognized laws of combination
that Liebig is unwilling to admit the new force at all to which
Berzelius had given the name so generally accepted.

The phenomena of isomerism, or identity of composition and proportions
of constituents with difference of qualities, and of isomorphism, or
identity of form in crystals which have one element substituted for
another, were equally surprises to science; and although the mechanism
by which they are brought about can be to a certain extent explained
by a reference to the hypothetical atoms of which the elements are
constituted, yet this is only turning the difficulty into a fraction
with an infinitesimal denominator and an infinite numerator.

So far we have studied the working of force and its seeming anomalies
in purely chemical phenomena. But we soon find that chemical force is
developed by various other physical agencies,--by heat, by light, by
electricity, by magnetism, by mechanical agencies; and, vice versa, that
chemical action develops heat, light, electricity, magnetism, mechanical
force, as we see in our matches, galvanic batteries, and explosive
compounds. Proceeding with our experiments, we find that every kind
of force is capable of producing all other kinds, or, in Mr. Faraday's
language, that "the various forms under which the forces of matter are
made manifest have a common origin, or, in other words, are so directly
related and mutually dependent that they are convertible one into
another."

Out of this doctrine naturally springs that of the conservation of
force, so ably illustrated by Mr. Grove, Dr. Carpenter, and Mr. Faraday.
This idea is no novelty, though it seems so at first sight. It was
maintained and dispu