CIV
§ 262. Also the form of a body influences the way in
which electricity is distributed. If the body has a spherical
form, electricity is equally charged all over the surface; in elon
gated bodies it accumulates towards the points, and here of
course tension is increased. About the power of points see:
432.
§ 263. The influence of an electrified body upon neutral
bodies exerted through air or other insulating bodies is called
electrification by induction. In this respect again the same
may be observed, what we have met with in magnetism (see
coercive force: § 243). Although good conductors may easi
ly be electrified, it is only temporary, bad conductors are not so
easily acted upon by induction, but when once charged the
electric state is far more permanent.
§ 264. 3) The most important instrument in connection
with frictional electricity are:
a) The Electrosphorus, an instrument by which large
quantities of electricity may not only be produced but also kept
for a long time, 428. It consists of a cake of resin placed on
a metallic surface; on the cake we place a wooden disc, lined
on its under surface with tinfoil and provided with an insulat
ed glass-handle (“the cover”). The chief experiments made
with the electrophorus are the following:
1). The electrophorus is insulated, the cake flapped with
a cat skin and cake as well as the form will show negative
electricity.
2) Place the cover on it and it will show negative electricity,
whilst that of the form is weakened. If the cover is removed, it
loses its electricity and that of the form is strengthened again.
3) Place the cover on it, touch the cover with the finger
and a spark will spring off; the form shows positive electricity. If
