pper say, is steeped in a solution of the coating substance, and
connected by means of wires with a galvanic battery, under the action of
which the metal in solution unites with the surface of the plate
immersed in it. Heat also is developed under magnetic influence, and
that often of great intensity. Thus, if we connect the poles of a
voltaic battery by means of a platinum wire, heat will develop to such a
degree that the platinum will almost instantaneously become red hot and
emit a bright light, and that along a wire of some considerable length.
A similar effect is noticeable when we substitute other metals, such as
silver or iron, for platinum. And the _electric light_, which flashes
out rays of sunlike brilliance, is the result of placing a piece of
compact charcoal between the separated but confronting poles of a
powerful galvanic battery, light, developing more at the one pole and
heat more at the other of the incandescent substance.

Kindred, though much milder, results will show themselves under simpler,
though similar, contrivances. A flounder will jump and jerk about
uneasily if we lay it upon a piece of tinfoil and place over it a thin
plate of zinc, and then connect the two with a bent metal rod; which
will happen to an eel also, if we expose it to a gentle current from a
battery.

By means of electric or magnetic action we can separate bodies
chemically combined, as well as unite them into chemical compounds; as
will appear if we place a piece of blotting paper upon tinfoil, and this
upon wool; if we then spread above these two pieces of test-paper,
litmus and turmeric, the one the test of acids, and the other of
alkalis, and saturate both with Glauber salt (which is by itself neither
an acid nor an alkali, but a combination of the two), and, finally,
connect each by means of a piece of zinc with the poles of a battery,
the test-papers will immediately change colour, as they do the one in
the presence of an acid simply, and the other of an alkali simply, but
never in a compound where these are neutralised; thus proving that the
compound has in this case been decomposed, and its elements
disintegrated one from another.

A very powerful magnet can be produced by coiling a wire round a bar of
soft iron, and attaching its extremities to the poles of a galvanic
battery, when it will be found that its strength will be proportioned to
the strength of the current and the turns of the coil. This is
especially th