ELECTRICAL ATTRACTION AND REPULSION.
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.