rs, or when the quantity of
electricity evolved or transmitted in a given time is very small.

317. A piece of litmus paper moistened in solution of common salt or
sulphate of soda, was quickly reddened at _p_. A similar piece moistened in
muriatic acid was very soon bleached at _p_. No effects of a similar kind
took place at _n_.

318. A piece of turmeric paper moistened in solution of sulphate of soda
was reddened at _n_ by two or three turns of the machine, and in twenty or
thirty turns plenty of alkali was there evolved. On turning the paper
round, so that the spot came under _p_, and then working the machine, the
alkali soon disappeared, the place became yellow, and a brown alkaline spot
appeared in the new part under _n_.

319. On combining a piece of litmus with a piece of turmeric paper, wetting
both with solution of sulphate of soda, and putting the paper on the glass,
so that _p_ was on the litmus and _n_ on the turmeric, a very few turns of
the machine sufficed to show the evolution of acid at the former and alkali
at the latter, exactly in the manner effected by a volta-electric current.

320. All these decompositions took place equally well, whether the
electricity passed from the machine to the foil _a_, through water, or
through wire only; by _contact_ with the conductor, or by _sparks_ there;
provided the sparks were not so large as to cause the electricity to pass
in sparks from _p_ to _n_, or towards _n_; and I have seen no reason to
believe that in cases of true electro-chemical decomposition by the
machine, the electricity passed in sparks from the conductor, or at any
part of the current, is able to do more, because of its tension, than that
which is made to pass merely as a regular current.

321. Finally, the experiment was extended into the following form,
supplying in this case the tidiest analogy between common and voltaic
electricity. Three compound pieces of litmus and turmeric paper (319.) were
moistened in solution of sulphate of soda, and arranged on a plate of glass
with platina wires, as in fig. 45. The wire _m_ was connected with the
prime conductor of the machine, the wire _t_ with the discharging train,
and the wires _r_ and _s_ entered into the course of the electrical current
by means of the pieces of moistened paper; they were so bent as to rest
each on three points, _n, r, p; n, s, p_, the points _r_ and _s_ being
supported by the glass, and the others by the papers; the three