Let the tin tube, with a pair of balls at one end, be placed three
feet at least from any part of the room, and the air rendered very
dry by means of a fire: electrify the apparatus to a considerable
degree; then touch the tin tube with a finger, or any other
conductor, and the balls will, notwithstanding, continue to repel
each other; though not at so great a distance as before.
The air surrounding the apparatus to the distance of two or three
feet, is supposed to contain more or less of the electrical fire,
than its common share, as the tin tube is electrified positively,
or negatively; and when very dry, may not part with its overplus,
or have its deficiency supplied so suddenly, as the tin; but may
continue to be electrified, after that has been touched for a
considerable time.