« ZurückWeiter »
moist on the outside, if such moisture continue up to the cork or wire.
Place a man on a cake of wax, and present him the wire of the electrified phial to touch, you standing on the floor, and holding it in your hand. As often as he touches it, he will be electrified plus; and any one standing on the floor may draw a spark from him. The fire in this experiment passes out of the wire into him; and at the same time out of your hand into the bottom of the bottle.
Give him the electrical phial to hold; and do you touch the wire; as often as you touch it, he will be electrified minus, and may draw a spark from any one standing on the floor. The fire now passes from the wire to you, and from him into the bottom of the bottle.
Lay two books on two glasses, back towards back, two or three inches distant. Set the electrified phial on one, and then touch the wire; that book will be electrified minus; the electrical fire being drawn out of it by the bottom of the bottle. Take off the bottle, and, holding it in your hand, touch the other with the wire; that book will be electrified plus; the fire passing into it from the wire, and the bottle at the same time supplied from your hand. A suspended small cork ball will play between these books till the equilibrium is restored.
When a body is electrized plus, it will repel a positively electrified feather or small cork ball. When minus (or when in the common state), it will attract them, but stronger when minus than when in the common state, the difference being greater.
Though, as in Experiment VI, a man standing on wax may be electrized a number of times by repeatedly touching the wire of an electrized bottle (held in the hand of one standing on the floor), he receiving the fire from the wire each time; yet holding it in his own hand, and touching the wire, though he draws a strong spark, and is violently shocked, no electricity remains in him; the fire only passing through him, from the upper to the lower part of the bottle. Observe, before the shock, to let some one on the floor touch him to restore the equilibrium in his body; for, in taking hold of the bottom of the bottle, he sometimes becomes a little electrized minus, which will continue after the shock, as would also any plus electricity, which he might have given him before the shock. For restoring the equilibrium in the bottle does not at all affect the electricity in the man through whom the fire passes; that electricity is neither increased nor diminished.
The passing of the electrical fire from the upper to the lower part* of the bottle, to restore the equilibrium, is rendered strongly visible by the following pretty experiment. Take a book whose covering is filleted with gold; bend a wire of eight or ten inches long, in the form of (m), Fig. 5; slip it on the end of the cover of the book, over the gold line, so as that the shoulder of it may press upon one end of the gold line, the ring up, but leaning towards the other end of the book Lay the book on a glass or wax,* and on the other end of the gold lines set the bottle electrized; then bend the springing wire, by pressing it with a stick of wax, till its ring approaches the ring of the bottle wire; instantly there is a strong spark and stroke, and the whole line of gold, which completes the communication between the top and bottom of the bottle, will appear a vivid flame, like the sharpest lightning. The closer the contact between the shoulder of the wire and the gold at one end of the line, and between the bottom of the bottle and the gold at the other end, the better the experiment succeeds. The room should be darkened. If you would have the whole filleting round the cover appear in fire at once, let the bottle and wire touch the gold in the diagonally opposite corners.
* That is, from the inside to the outside.
I am, &c.
TO PETER COLMNSON.
Farther Experiments confirming the preceding Observations. — Leyden Bottle analyzed. — Electrical Battery. — Magical Picture. —Electrical Wheel or Jack. — Electrical Feast. >j.
Sir, § 1. There will be the same explosion and shock if the electrified phial is held in one hand by the hook, and the coating touched with the other, as when held by the coating, and touched at the hook.
* Placing the book on glass or wax is not necessary to produce' t appearance; it is only to show that the visible electricity is not bron iip from the common stock in the earth.