ever, to commit the following results to

your memory.

(1.) Bodies that are electrified positively repel each other.

(2.) Bodies that are electrified negatively repel each other.

Charles. Do you mean, that if two bodies have either more or less of the electric fluid than their natural share, they will repel each other if brought sufficiently near?

Tutor. That is exactly what I mean.

(3.) Bodies electrified by contrary powers; that is, two bodies, one having more, and the other less, than its natural share, attract each other very strongly.

(4.) Bodies that are electrified attract light substances which are not electrified.

These are facts which, I trust have been made evident to your senses. To-morrow we will decribe what is usually called the Leyden phial.

CONVERSATION XXXIII.

Of the Leyden Phial or Jar.

TUTOR. I will take away the wires and the ball from the conductor, and then remove the conductor an inch or two farther from the cylinder. If the machine acts strongly, bring an insulated pith-ball, that is, you know, one hanging on silk, to the end of the conductor, nearest to the glass cylinder.

Charles. It is immediately attracted.

Tutor. Carry it to the other end of the conductor, and see what happens.

Charles. It is attracted again; but I thought it would have been repelled.

Tutor. Then as the ball was electrified before, and is still attracted, you are sure that the electricity of the two ends of the conductor are of different names; that is, one is plus, and the other minus.

James. Which is the positive, and which is the negative end?

Tutor. That end of the conductor which is nearest to the cylinder, becomes possessed of an electricity different from that of the cylinder itself.

James

Do you mean that if the cylinder is positively electrified, the end of the conductor next to it is electrified negative. ly?

Tutor. I do and this you may see by holding an insulated pith-ball between them.

Charles. Yes, it is now very evident, for the ball fetches and carries as we have seen it before.

Tutor. What you have seen with regard to the conductor, is equally true with respect to non-conducting bodies. Here is a common glass tumbler: if I throw within

side it a greater portion of electricity than its natural share, and hold it in my hand, or place it on any conducting substance, as a table, a part of the electric fluid, that naturally belongs to the outside, will make its escape through my body, on the table. Charles. Let me try this.

Tutor. But you must be careful that you do not break the glass.

Charles. I will hang the chain on the conductor, and let the other end lie on the bottom of the glass, and James will turn the machine.

Tutor. You must take care that the chain does not touch the edge of the glass, because when the electric fluid will, by that means, run from one side of it to the other, and spoil the experiment.

James. If I have turned the machine enough, take the chain out, and try the two sides with the insulated pith-ball.

Charles. What is this? Something has pierced through my arms and shoulders.

Tutor. That is a trifling electrical shock, which you might have avoided, if you had waited for my directions.

Charles. Indeed it was not trifling: I feel it now.

Tutor. This leads us to the Leyden phial: so called, because the discovery was first made at Leyden, in Holland, and by means of a phial or small bottle.

James. Was it found out in the same manner as Charles has just discoverd it?

Tutor. Nearly so. Mr. Cuneus, a Dutch philosopher, was holding a glass phial in his hand, about half filled with water, but the sides above the water, and the outside was quite dry, a wire also hung from the conductor of an electrical machine into the wa ter.

James. Did that answer to the chain?

Tutor. Just so: and, like Charles, he was going to disengage the wire with one hand, as he held the bottle in the other, and was surprised and alarmed by a sudden shock in his arms, and through his breast, which he had not the least expected.