Rub a piece of amber, a stick of red sealing-wax, or a smooth glass
tube, smartly upon the sleeve of a coat, or any other dry woollen
substance, and it will attract to itself bits of straw, paper,
fragments of gold leaf, or any small and light bodies. The amber, wax,
or glass, is then said to be excited, and the attractive power thus
developed, is called electrical attraction.
Select a clean and dry downy feather, and suspend it from a beam by a
long thread of white silk; to be used in the following experiments:
Provide a glass tube, about three feet long and three quarters of
an inch diameter; wipe it dry, and rub it gently with a warm silk
handkerchief; then apply the tube to the feather, and it will _attract_
it; withdraw the tube gently, apply it again, and the feather will be
repelled for a time, but then attracted, and then again repelled. In
this case, the feather having received electricity from the glass, is
repelled by it; for bodies similarly electrified repel each other.
Fold a silk handkerchief, warm it, and with it rub the tube; apply it
to the feather, and it will first attract and then repel it; when the
feather has just been repelled by the silk, apply the tube, and the
feather will be attracted. The handkerchief must be folded so thickly
as to keep the hand as far as possible from the glass tube.
Roll up flannel thickly, rub it with sealing-wax, and the roll will
by turns attract and repel the feather; when thus repelled, apply the
excited wax, and it will instantly attract the feather.
When the atmosphere is dry, take in one hand a rod of glass and
in the other a stick of sealing-wax, and rub them against silk or
worsted; with one of them approach a bit of gold-leaf, floating in
the air, it will first attract and then repel it. When the gold has
just been repelled, approach it with the other rod, and it will be
immediately attracted; and this alternate attraction and repulsion may
be strikingly displayed by placing the two excited rods at a small
distance asunder, with the gold leaf between them.