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 the case when the bar is bent into the form of a horse-shoe,
and the wires are insulated and coiled round its limbs. The force
communicated to a magnet of this kind, which is often immense, is the
product of the chemical action which goes on in the battery, and, in a
certain sense, the measure of it. How great that is we may judge when
we consider that, evanescent as it is in itself, it has imparted a
virtue which is both powerful and constant, and ever at our service.

_Summary_.--Thus, then, on a review of the whole, we find all things are
endowed with attractive power, and that there is no particle which is
not directly or indirectly related, in manifold ways, to the other
particles of the universe. There is, first, the universal attraction of
gravitation, under which every particle is, by a fixed law, drawn to