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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.
I am, &c.
TO PETER COLLINSON.
Farther Experiments confirming the preceding Obser
vations. — Leyden Bottle analyzed. — Electrical Battery. — Magical Picture. — Electrical Wheel or Jack. - Electrical Feast.
Philadelphia, 1748. 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 the appearance; it is only to show that the visible electricity is not brought up from the common stock in the earth.
2. To take the charged phial safely by the hook, and not at the same time diminish its force, it must first be set down on an electric per se.
3. The phial will be electrified as strongly, if held by the hook, and the coating applied to the globe or tube; as when held by the coating, and the hook applied.*
4. But the direction of the electrical fire, being different in the charging, will also be different in the explosion. The bottle charged through the hook, will be discharged through the hook; the bottle charged through the coating, will be discharged through the coating; and not otherways; for the fire must come out the same way it went in.
5. To prove this, take two bottles that were equally charged through the hooks, one in each hand; bring their hooks near each other, and no spark or shock will follow; because each hook is disposed to give fire, and neither to receive it. Set one of the bottles down on glass, take it up by the hook, and apply its coating to the hook of the other; then there will be an explosion and shock, and both bottles will be discharged.
6. Vary the experiment, by charging two phials equally, one through the hook, the other through the coating; hold that by the coating which was charged through the hook, and that by the hook which was charged through the coating ; apply the hook of the first to the coating of the other, and there will be no shock or spark. Set that down on glass which you held by the hook, take it up by the coating, and bring the two hooks together; a spark and shock will follow, and both phials be discharged.
* This was a discovery of the very ingenious Mr. Kinnersley, and by him communicated to me.
In this experiment the bottles are totally discharged, or the equilibrium within them restored. The abounding of fire in one of the hooks (or rather in the internal surface of one bottle) being exactly equal to the wanting of the other; and therefore, as each bottle has in itself the abounding as well as the wanting, the wanting and abounding must be equal in each bottle. See § 8, 9, 10, 11. But if a man holds in his hands two bottles, one fully electrified, the other not at all
, and brings their hooks together, he has but half a shock, and the bottles will both remain half electrified, the one being half discharged, and the other half charged.
7. Place two phials equally charged on a table, at five or six inches distance. Let a cork ball, suspended by a silk thread, hang between them. If the phials were both charged through their hooks, the cork, when it has been attracted and repelled by the one, will not be attracted, but equally repelled by the other. But, if the phials were charged, the one through the hook, and the other through the coating,* the ball, when it is repelled from one hook, will be as strongly attracted by the other, and play vigorously between them, fetching the electric fluid from the one, and delivering it to the other, till both phials are nearly discharged.
8. When we use the terms of charging and discharging the phial, it is in compliance with custom, and for want of others more suitable. Since we are of opinion, that there is really no more electrical fire in the phial after what is called its charging, than before, nor less after its discharging ; excepting only the small spark
* To charge a bottle commodiously through the coating, place it on a glass stand; form a communication from the prime conductor to the coating, and another from the hook to the wall or floor. When it is charged, remove the latter communication before you take hold of the bottle, otherwise great part of the fire will escape by it.