is less
liable to oxydise or rust in it. This is one reason, among others, why
gold is the most precious metal, and the conventional representative of
highest worth in things.

There are some metals, such as lead, for instance, which oxydise
readily, but this process stops short at the surface in contact with the
air, and so forms a coating which prevents the metal from further
oxydation; so that here, as in so many things else, strength is
connected with weakness.

_Electricity_.--This, in the most elementary view of it, is a more or
less attractive or repellant force latent in bodies, and which is
capable of being roused into action by the application of friction. It
is excited in a rod of glass by rubbing it with silk, and in a piece of
sealing-wax by rubbing it with flannel, though the effect is different
when we apply first the one and then the other to the same body. Thus,
_e.g._, if we apply the excited sealing-wax to a paper ring, or a
pith-ball, hung by a silk thread from a horizontal glass rod, it will,
after contact, repel it; and if, thereafter, we apply to it the excited
glass rod, it will attract it; or if we first apply the excited glass
rod to the paper ring, or pith-ball, it will, after contact, repel it;
and if thereafter we apply to it the excited sealing-wax, it will
attract it. The reason is, that when we once charge a body by contact
with either kind, it repels that kind, and attracts the opposite; if we
charge it from the glass, _i.e._, with vitreous electricity, it refuses
to have more, and is attracted to the sealing-wax; and if we charge it
from the sealing-wax, _i.e._, with resinous electricity, it refuses to
have more, and is attracted to the glass-rod; only it is to be observed
that, till the body is charged by either, it has an equal attraction for
both. From all which it appears that kindred electricities repel, and
opposite attract, each other.

Two pieces of gold leaf suspended from a metal rod, inserted at the top
of a glass shade full of perfectly pure, dry air, will separate if we
rub our foot on the carpet, and touch the top of the rod with one of our
fingers; for the motion of the body, as in walking, always excites
electricity, and it is this which, as it passes through the finger,
causes the phenomenon; though the least sensation of damp in the glass
would, by instantly draining off the electricity, defeat the experiment.
What happens in this case is, that one kind of electrici