lf was
in an equally opposite state, an _inductive_ charge and not an _absolute_
charge having been acquired.

1172. Well-purified oil of turpentine, which I find to be an excellent
liquid insulator for most purposes, was put into a metallic vessel, and,
being insulated, an endeavour was made to charge its particles, sometimes
by contact of the metal with the electrical machine, and at others by a
wire dipping into the fluid within; but whatever the mode of communication,
no electricity of one kind only was retained by the arrangement, except
what appeared on the exterior surface of the metal, that portion being
present there only by an inductive action through the air to the
surrounding conductors. When the oil of turpentine was confined in glass
vessels, there were at first some appearances as if the fluid did receive
an absolute charge of electricity from the charging wire, but these were
quickly reduced to cases of common induction jointly through the fluid, the
glass, and the surrounding air.

1173. I carried these experiments on with air to a very great extent. I had
a chamber built, being a cube of twelve feet. A slight cubical wooden frame
was constructed, and copper wire passed along and across it in various
directions, so as to make the sides a large net-work, and then all was
covered in with paper, placed in close connexion with the wires, and
supplied in every direction with bands of tin foil, that the whole might be
brought into good metallic communication, and rendered a free conductor in
every part. This chamber was insulated in the lecture-room of the Royal
Institution; a glass tube about six feet in length was passed through its
side, leaving about four feet within and two feet on the outside, and
through this a wire passed from the large electrical machine (290.) to the
air within. By working the machine, the air in this chamber could be
brought into what is considered a highly electrified state (being, in fact,
the same state as that of the air of a room in which a powerful machine is
in operation), and at the same time the outside of the insulated cube was
everywhere strongly charged. But putting the chamber in communication with
the perfect discharging train described in a former series (292.), and
working the machine so as to bring the air within to its utmost degree of
charge if I quickly cut off the connexion with the machine, and at the same
moment or instantly after insulated the cube, the air