rass hemisphere (fig. 110.), observations were made
with the carrier ball as before (1224.). The results were the same, and the
circumstance of some of the positions being within the fluid and some
without, made no sensible difference.

1228. Lastly, I used a few solid dielectrics for the same purpose, and with
the same results. These were shell-lac, sulphur, fused and cast borate of
lead, flint glass well-covered with a film of lac, and spermaceti. The
following was the form of experiment with sulphur, and all were of the same
kind. A square plate of the substance, two inches in extent and 0.6 of an
inch in thickness, was cast with a small hole or depression in the middle
of one surface to receive the carrier ball. This was placed upon the
surface of the metal hemisphere (fig. 112.) arranged on the excited lac as
in former cases, and observations were made at _n, o, p_, and _q_. Great
care was required in these experiments to free the sulphur or other solid
substance from any charge it might previously have received. This was done
by breathing and wiping (1203.), and the substance being found free from
all electrical excitement, was then used in the experiment; after which it
was removed and again examined, to ascertain that it had received no
charge, but had acted really as a dielectric. With all these precautions
the results were the same: and it is thus very satisfactory to obtain the
curved inductive action through _solid bodies_, as any possible effect from
the translation of charged particles in fluids or gases, which some persons
might imagine to be the case, is here entirely negatived.

1229. In these experiments with solid dielectrics, the degree of charge
assumed by the carrier ball at the situations _n, o, p_ (fig. 112.), was
decidedly greater than that given to the ball at the same places when air
only intervened between it and the metal hemisphere. This effect is
consistent with what will hereafter be found to be the respective relations
of these bodies, as to their power of facilitating induction through them
(1269. 1273. 1277.).

1230. I might quote _many_ other forms of experiment, some old and some
new, in which induction in curved or contorted lines takes place, but think
it unnecessary after the preceding results; I shall therefore mention but
two. If a conductor A, (fig. 111.) be electrified, and an uninsulated
metallic ball B, or even a plate, provided the edges be not too thin, be
held before it,