Charles. Would it serve any other non-conducting substance in the same man

ner?

Tutor. Yes, it will even break a thin piece of glass, or of resin, or of sealingwax, if they be interposed between the discharging rod and the outside of the coating of the battery.

Example 2. Place a piece of loaf-sugar in the situation in which the quire of paper was just now, the sugar will be broken, and in the dark it will appear beautifully illuminated, and remain so for many seconds of time.

Example 3. Let the small piece of wire, proceeding from the hole in the box, be laid on one side of a plate, containing some spirits of wine, and, on the opposite side of the plate, bring one of the knobs of the discharging-rod, while the other is carried to the wires connected with the inside of

the jars.

Charles. Then the electric fluid will have a passage through the spirit?

Tutor. It will set it on fire instantly. Example 4. Take two slips of common window-glass, about four inches long, and one inch broad: put a slip of gold-leaf between the glasses, leaving a small part of it out at each end, then tie the glasses together, or press them with a heavy weight, and send the charge of the battery through it, by connecting one end of the glass with the outside of the jars, and bringing the discharging-rod to the other end, and to the wires of the inside of the bat tery.

James. Will it break the glass?

Tutor. It probably will: but whether it does or not, the gold-leaf will be forced into the pores of the glass, so as to appear like glass stained with gold, which nothing can wash away.

Example 5. If the gold-leaf be put between two cards, and a strong charge passed through it, it will be completely fused or melted, the marks of which will appear on the card.

This instrument, (Plate vII. Fig. 11.) called an universal discharger, is very useful for passing charges through many substances. BB are glass pillars cemented into the frame A. To each of the pillars is cemented a brass cap, and a double joint for horizontal and vertical motions; on the top of each joint is a spring tube, which holds the sliding wires c x, cx, so that they may be set at various distances from each other, and turned in any direction; the extremities of the wires are pointed, but with screws, at about half an inch from the points, to receive balls. The table E D, inlaid with a piece of ivory, is made to move up and down in a socket, and a screw fastens it to any required height. The rings c c are very convenient for fixing a chain or wire to them, which proceeds from the conductor.

Charles. Do you lay any thing on the ivory, between the balls, when you want to send the charge of a battery through it ?

Tutor. Yes; and by drawing out the wires, the balls may be separated to any distance less than the length of the ivory. The figure H (Plate VII. Fig. 12.) represents a press, which may be substituted in the place of the table E D. It consists of two flat pieces of mahogany, which may be brought together by screws.

James. Then instead of tying the slips of glass together in Example 4, you might have done it better by making use of the press ?

Tutor. I might; but I was willing to show you how the thing might be done, if no such apparatus as this were at hand. The use of the table and press, which, in fact, always go together, is for keeping steady all descriptions of bodies through which the charge of a single jar, or any number of which a battery consists, is to be conveyed. We will now proceed with the experiments.

Example 6. I will take the knobs from the wires of the universal dischar

ger, and having laid a piece of very dry writing paper on the table E, I place the points of the wires at an inch or more from one another; then, by connecting one of the rings c with the outside wire or hook of the battery, and bringing the discharging-rod from the other ring c to one of the knobs of the battery, you will see that the paper will be torn to pieces.

Example 7. The experiment which I am now going to make, you must never attempt by yourselves: I put a little gunpowder in the tube of a quill, open at both ends, and insert the pointed extremities of the two wires in it, so as to be within a quarter of an inch or less from each other. I now send the charge of the battery through it, and the gunpowder, you see, is instantly inflamed.

Example 8. Here is a very slender wire, not a hundredth part of an inch in diameter, which I connect with the wires of the discharger, and send the charge