_Proving that the Leyden Bottle has no more electrical Fire in
it when charged, than before: nor less when discharged: that, in
discharging, the Fire does not issue from the Wire and the Coating
at the same Time, as some have thought, but that the Coating always
receives what is discharged by the Wire, or an equal Quantity; the
outer Surface being always in a negative State of Electricity, when
the inner Surface is in a positive State._
Place a thick plate of glass under the rubbing cushion, to cut off
the communication of electrical fire from the floor to the cushion;
then if there be no fine points or hairy threads sticking out from
the cushion, or from the parts of the machine opposite to the
cushion, (of which you must be careful) you can get but a few sparks
from the prime conductor, which are all the cushion will part with.
Hang a phial then on the prime conductor, and it will not charge
though you hold it by the coating.--But,
Form a communication by a chain from the coating to the cushion, and
the phial will charge.
For the globe then draws the electric fire out of the outside surface
of the phial and forces it through the prime conductor and wire of
the phial into the inside surface.
Thus the bottle is charged with its own fire, no other being to be
had while the glass plate is under the cushion.
Hang two cork balls by flaxen threads to the prime conductor; then
touch the coating of the bottle, and they will be electrified and
recede from each other.
For just as much fire as you give the coating, so much is discharged
through the wire upon the prime conductor, whence the cork balls
receive an electrical atmosphere.--But,
Take a wire bent in the form of a C, with a stick of wax fixed to
the outside of the curve, to hold it by; and apply one end of this
wire to the coating, and the other at the same time to the prime
conductor, the phial will be discharged; and if the balls are not
electrified before the discharge, neither will they appear to be so
after the discharge, for they will not repel each other.
If the phial really exploded at both ends, and discharged fire from
both coating and wire, the balls would be _more_ electrified, and
recede _farther_; for none of the fire can escape, the wax handle
preventing.
But if the fire with which the inside surface is surcharged be
so much precisely as is wanted by the outside surface, it will
pass round through the wire fixed to the wax handle, restore the
equilibrium in the glass, and make no alteration in the state of the
prime conductor.
Accordingly we find, that if the prime conductor be electrified,
and the cork balls in a state of repellency before the bottle is
discharged, they continue so afterwards. If not, they are not
electrified by that discharge.