Wollaston 7s JKxperiment 17

ordinary electricity. By covering fine wires with glass or other
insulating substances, and then removing only so much matter
as to expose the point, or a section of the wires, and by passing
electricity through two such wires, the guarded points of which
were immersed in water, Wollaston found that the water could
be decomposed even by the current from the machine, without
sparks, and that two streams of gas arose from the points,
exactly resembling, in appearance, those produced by voltaic
electricity, and, like the latter, giving a mixture of oxygen and
hydrogen gases. But Dr. Wollaston himself points out that
the effect is different from that of the voltaic pile, inasmuch as
both oxygen and hydrogen are evolved from each pole; he calls
it " a very close imitation of the galvanic phenomena/' but adds
that " in fact the resemblance is not complete/' and does not
trust to it to establish the principles correctly laid down in his
paper.

64. This experiment is neither more nor less than a repetition,
in a refined manner, of that made by Dr. Pearson in 1797,*
and previously by MM. Paets Van Troostwyk and Deiman in
1789 or earlier. That the experiment should never be quoted
as proving true electro-chemical decomposition, is sufficiently
evident from the circumstance, that the law which regulates
the transference and final place of the evolved bodies (14, 45)
has no influence here. The water is decomposed at both poles
independently of each other, and the oxygen and hydrogen
evolved at the wires are the elements of the water existing
the instant before in those places. That, the poles, or rather
points, have no mutual decomposing dependence, may be
shown by substituting a wire, or the finger, for one of them, a
change which does not at all interfere with the other, though it
stops all action at the changed pole. This fact may be observed
by turning the machine for some time; for though bubbles
will rise from the point left unaltered, in quantity sufficient
to cover entirely the wire used for the other communication, if
they could be applied to it, yet not a single bubble will appear
on that wire.

65. When electro-chemical decomposition takes place, there
is great reason to believe that the quantity of matter decom-
posed is not proportionate to the intensity, but to the quantity
of electricity passed (56). Of this I shall be able to offer some
proofs in a future part of this paper (in, 113). But in the
experiment under consideration, this is not the case. If, with

1 Nicholson's Journal, 4to, vol. i. pp. 241, 299, 349.

Bed pole. The whole instrument was protected