Definite Chemical Force 31

(105), so as always to form the positive pole, and at the same
time retain a perpendicular position, that it might rest, with
its whole weight,, upon the test paper to be employed. The
test paper itself was supported upon a platina spatula, con-
nected either with the discharging train (28), or with the negative
wire of the voltaic apparatus, and it consisted of four thick-
nesses, moistened at all times to an equal degree in a standard
solution of hydriodate of potassa (52).

no. When the platina wire was connected with the prime
conductor of the machine, and the spatula with the discharging
train, ten turns of the machine had such decomposing power as
to produce a pale round spot of iodine of the diameter of the
wire; twenty turns made a much darker mark, and thirty turns
made a dark brown spot penetrating to the second thickness
of the paper. The difference in effect produced by two or
three turns, more or less, could be distinguished with facility.

in. The wire and spatula were then connected with the ?.
voltaic apparatus (105), the galvanometer being also included C
in the arrangement; and, a stronger acid having been prepared,
consisting of nitric acid and water, the voltaic apparatus was
immersed so far as to give a permanent deflection of the need]e
to the 5J division (108), the fourfold moistened paper inter-
vening as before.1 Then by shifting the end of the wire from
place to place upon the test paper, the effect of the current for
five, six, seven, or any number of the beats of the watch (105)
was observed, and compared with that of the machine. After
alternating and repeating the experiments of comparison man}'
times, it was constantly found that this standard current of
voltaic electricity, continued for eight beats of the watch, was
equal, in chemical effect, to thirty turns of the machine; twenty-
eight revolutions of the machine were sensibly too few.

112. Hence it results that both in magnetic deflection (107)
and in chemical force, the current of electricity of the standard
voltaic battery for eight beats of the watch was equal to that of
the machine evolved by thirty revolutions.

113. It also follows that for this case of electro-chemical de-
composition, and it is probable for all cases, that the chemical
powt,r, like the magnetic force (102), is in direct proportion to
the absolute quantity of electricity which passes.

114. Hence arises still further confirmation, if any were
required, of the identity of common and voltaic electricity,

1 Of course the heightened power of the voltaic battery was necessary
to compensate for the bad conductor now interposed. with the voltaic apparatusuarterly Journal of Science, New Series, vol. i. p. 29),