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The Illuminated Vacuum


Take a tall receiver that is very dry, and fix through the top of it,

with cement, a blunt wire; then exhaust the receiver, and present the

knob of the wire to the conductor, and every spark will pass through

the vacuum in a broad stream of light, visible through the whole

length of the receiver, let it be as tall as it will. This generally

divides into a variety of beautiful rivulets, which are continually

changing th
ir course, uniting and dividing again in the most pleasing

manner.



If a jar be discharged through this vacuum, it presents the appearance

of a very dense body of fire, darting directly through the centre of

the vacuum, without touching the sides; whereas, when a single spark

passes through, it generally goes more or less to the side, and a

finger placed on the outside of the glass will draw it wherever a

person pleases. If the vessel be grasped by both hands, every spark is

felt like the pulsation of a large artery; and all the fire makes

towards the hands. This pulsation is even felt at some distance from

the receiver, and a light is seen between the hand and the glass.



All this while, the pointed wire is supposed to be electrified

positively; if it be electrified negatively, the appearance is

astonishingly different; instead of streams of fire, nothing is seen

but one uniform luminous appearance, like a white cloud, or the milky

way in a clear star-light night. It seldom reaches the whole length

of the vessel, but generally appears only at the end of the wire, like

a lucid ball.



If a small phial be inserted in the neck of a small receiver, so that

the external surface of the glass be exposed to the vacuum, it will

produce a very beautiful appearance. The phial must be coated on the

inside; and while it is charging, at every spark taken from the

conductor into the inside, a flash of light is seen to dart at the

same time from every part of the external surface of the phial, so as

to quite fill the receiver. Upon making the discharge, the light is

seen to run in a much closer body, the whole coming out at once.



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