himself the labour of repeating and examining the
facts, and then use his own judgement on them in preference to that of
others.

876. This state of the subject must, to those who have made up their minds
on the matter, be my apology for entering upon its investigation. The views
I have taken of the definite action of electricity in decomposing bodies
(783.), and the identity of the power so used with the power to be overcome
(855.), founded not on a mere opinion or general notion, but on facts
which, being altogether new, were to my mind precise and conclusive, gave
me, as I conceived, the power of examining the question with advantages not
before possessed by any, and which might compensate, on my part, for the
superior clearness and extent of intellect on theirs. Such are the
considerations which have induced me to suppose I might help in deciding
the question, and be able to render assistance in that great service of
removing _doubtful knowledge_. Such knowledge is the early morning light of
every advancing science, and is essential to its development; but the man
who is engaged in dispelling that which is deceptive in it, and revealing
more clearly that which is true, is as useful in his place, and as
necessary to the general progress of the science, as he who first broke
through the intellectual darkness, and opened a path into knowledge before
unknown to man.

877. The identity of the force constituting the voltaic current or
electrolytic agent, with that which holds the elements of electrolytes
together (855.), or in other words with chemical affinity, seemed to
indicate that the electricity of the pile itself was merely a mode of
exertion, or exhibition, or existence of _true chemical action_, or rather
of its cause; and I have consequently already said that I agree with those
who believe that the _supply_ of electricity is due to chemical powers
(857.).

878. But the great question of whether it is originally due to metallic
contact or to chemical action, i.e. whether it is the first or the second
which _originates_ and determines the current, was to me still doubtful;
and the beautiful and simple experiment with amalgamated zinc and platina,
which I have described minutely as to its results (863, &c.), did not
decide the point; for in that experiment the chemical action does not take
place without the contact of the metals, and the metallic contact is
inefficient without the chemical action. Hence either m