Electricity of the Voltaic Pile         173
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 througli the intellectual darkness,
and opened a path into knowledge before unknown to man.
 612.	The identity of the force constituting the voltaic current
or electrolytic agent, with that which holds the elements of elec-
trolytes together (590),, 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 (592).
 613.	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 experi-
ment with amalgamated zinc and platina, which I have described
minutely as to its results (598, etc.), 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 might
be looked upon as the determining cause of the current.
 614.	I thought it essential to decide this question by the
simplest possible forms of apparatus and experiment, that no
fallacy  might   be   inadvertently  admitted.    The   well-known
difficulty of effecting decomposition by a single pair of plates,
except in the fluid exciting. them into action (598), seemed to
throw insurmountable obstruction in the way of such experi-
ments;   but I remembered the easy decomposability of the
solution of iodide of potassium (52), and seeing no theoretical
reason, if metallic contact was not essential, why true electro-
decomposition should not be obtained without it, even in a
single circuit, I persevered and succeeded.
 615.	A plate of zinc, about eight inches long and half an
inch wide, was cleaned and bent in the middle to a right angle,
fig- 33? #•   A plate of platina, about three inches long and half
an inch wide, was fastened to a platina wire, and the latter bent
as in the figure, b.   These two pieces of metal were arranged
together as delineated, but as yet without the vessel c, and