Identity of Electricities I 3

48. A much more convenient and effectual arrangement for
chemical decompositions by common electricity is the following.
Upon a glass plate; fig. 4, placed over, but raised above a
piece of white paper, so that shadows may not interfere, put
two pieces of tinfoil a, b ; connect one of these by an insulated

Fig. 4.

wire c, or wire and string (37), with the machine,, and the other
g> with the discharging train (28) or the negative conductor;
provide two pieces of fine platina wire., bent as in fig. 5,'so
that the part d, f shall be nearly upright, whilst the whole is
resting on the three bearing points p, c, f; place these as in
fig. 4; the points p, n then become the decomposing poles. In
this way surfaces of contact, as minute as possible, can be
obtained at pleasure, and the connection can be broken or
renewed in a moment, and the sub-
stances acted upon examined with the
utmost facility.

49. A coarse line was made on the
glass with solution of sulphate of copper,
and the terminations p and n put into
it; the foil a was connected with the
positive conductor of the machine by

wire and wet string, so that no sparks g* 5

passed: twenty turns of the machine caused the precipitation
of so much copper on the end n, that it looked like copper
wire; no apparent change took place at p.

50. A mixture of equal parts of muriatic acid and water
was rendered deep blue by sulphate of indigo, and a large drop
put on the glass, fig. 4, so that p and n were immersed at
opposite sides: a single turn of the machine showed bleaching
effects round p, from evolved chlorine. After twenty revolu-
tions no effect of the kind was visible at n, but so much chlorine

w mr imm

IKTITUK OF TEGHOUft

of the experiments,