FIG. 4. Let a ring of thin lead, or paper, surround a bottle (_i_)
even at some distance from or above the bottom. From that ring let a
wire proceed up, till it touch the wire of the cork (_k_). A bottle
so fixt cannot by any means be electrised: the equilibrium is never
destroyed: for while the communication between the upper and lower
parts of the bottle is continued by the outside wire, the fire only
circulates: what is driven out at bottom, is constantly supplied
from the top[30]. Hence a bottle cannot be electrised that is foul
or moist on the outside, if such moisture continue up to the cork or
wire.