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 electrised plus; the fire passing into it from the wire, and the bottle at the same time supply'd from your hand. A suspended small cork-ball will play between these books 'till the equilibrium is restored.
EXPERIMENT IX.
When a body is electrised plus it will repel an 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.
EXPERIMENT X.
Tho', as in EXPER. VI. a man standing on wax may be electrised a number of times, by repeatedly touching the wire of an electrised 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, tho' he draws a strong spark, and is violently shock'd, no Electricity remains in him; the fire only passing thro' 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 electrised 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 thro' whom the fire passes; that Electricity is neither increased nor diminish'd.
EXPERIMENT XI.
The passing of the electrical fire from the upper to the lower part of the bottle, to restore the equilibrium is render'd strongly visible by the following pretty experiment. Take a book whose cover is filletted 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 electrised: 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 filletting round the cover appear in fire at once, let the bottle and wire touch the gold in the diagonally opposite corners.
I am, &c.
B. FRANKLIN.