Page:Popular Science Monthly Volume 9.djvu/360

 338 This experience agrees with mine. In the theatre of the Royal Institution, and in the presence of an audience, I once received the discharge of a battery of fifteen Leyden-jars. Unlike Franklin's six men, I did not fall, but, like them, I felt nothing. I was simply extinguished for a sensible interval.

This may be regarded as an experimental proof that people killed by lightning suffer no pain.

21. Seat of Charge in the Leyden-Jar.—Franklin sought to determine how the charge was hidden in the Leyden-jar. He charged with electricity a bottle half-filled with water and coated on the outside with tin-foil; dipping the finger of one hand into the water, and touching the outside coating with the other, he received a shock. He was thus led to inquire, Is the electricity in the water? He poured the water into a second bottle, examined it, and found that it had carried no electricity along with it.

His conclusion was, that "the electric fire must either have been lost in the decanting or must have remained in the bottle. The latter he found to be true; for, filling the charged bottle with fresh water, he obtained the shock, and was, therefore, satisfied that the power of giving it resided in the glass itself." An account of Franklin's discoveries was given by him in a series of letters addressed to Peter Collinson, Esq., F.R.S., from 1747 to 1754.

So much for history; but you are to verify the history by repeating Franklin's experiments. Place water in a wide glass vessel; place a second glass vessel within the first, and fill it to the same height with water. Connect the outer water by a wire with the earth, and the inner water by a wire with the electric machine. One or two turns furnish a sufficient charge. Removing the inner wire, and dipping one finger into the outside and the other into the inside water, a smart shock is felt. This was Franklin's first experiment.

Pass on to the second. Coat a glass jar with tin-foil (not too high); fill it to the same height with water, and place it on India-rubber cloth. Charge it by connecting the outside coating with the earth, and the water inside (by means of a stem cemented to the bottom of the jar and a knob) with an electric machine. You obtain a bright spark on discharging. This proves your apparatus to be in good order.

Recharge. Take hold of the charged jar with the India-rubber, and pour the water into a second similar jar. No sensible charge is imparted to the latter. Pour fresh unelectrifled water into the first jar, and discharge it. The retention of the charge is shown by a brilliant spark. Be careful in these experiments, or you will fail, as I did at first. Note that the edge of the jar out of which the water is poured is to be surrounded by a band of bibulous paper to catch the final drop.