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Electrified Air

Fix two or three pointed needles into the prime conductor of an

electrical machine, and set the glass in motion so as to keep the

prime conductor electrified for several minutes. If now, an

electometer be brought within the air that is contiguous to the prime

conductor, it will exhibit signs of electricity, and this air will

continue electrified for some time, even after the machine has been

removed into another room.
he air, in this case, is electrified

positively; it maybe negatively electrified by fixing the needles in

the negative conductor while insulated, and making a communication

between the prime conductor and the table, by means of a chain or

other conducting substance.

The air of a room may be electrified in another way. Charge a large

jar, and insulate it; then connect two or more sharp-pointed wires or

needles, with the knob of the jar, and connect the outside coating of

the jar with the table. If the jar be charged positively, the air of

the room will soon become positively electrified likewise; but if the

jar be charged negatively, the electricity communicated by it to the

air will also become negative. A charged jar being held in one hand,

and the flame of an insulated candle held in the other being brought

near the knob of the jar, will also produce the same effect.