ck contact
with the spermaceti apparatus, ascertain what was left in the former
(1281.), no great confidence can be placed in the results. They are not in
opposition to the general conclusion, but cannot be brought forward as
argument in favour of it.

* * * * *

1280. I endeavoured to find some liquids which would insulate well, and
could be obtained in sufficient quantity for these experiments. Oil of
turpentine, native naphtha rectified, and the condensed oil gas fluid,
appeared by common experiments to promise best as to insulation. Being left
in contact with fused carbonate of potassa, chloride of lime, and quick
lime for some days and then filtered, they were found much injured in
insulating power; but after distillation acquired their best state, though
even then they proved to be conductors when extensive metallic contact was
made with them.

1281. _Oil of turpentine rectified._--I filled the lower half of app. i.
with the fluid: and as it would not hold a charge sufficiently to enable me
first to measure and then divide it, I charged app. ii. containing air, and
dividing its charge with app. i. by a quick contact, measured that
remaining in app. ii.: for, theoretically, if a quick contact would divide
up to equal tension between the two apparatus, yet without sensible loss
from the conducting power of app. i.; and app. ii. were left charged to a
degree of tension above half the original charge, it would indicate that
oil of turpentine had less specific inductive capacity than air; or, if
left charged below that mean state of tension, it would imply that the
fluid had the greater inductive capacity. In an experiment of this kind,
app. ii. gave as its charge 390 deg. before division with app. i., and 175 deg.
afterwards, which is less than the half of 390 deg.. Again, being at 176 deg.
before division, it was 79 deg. after, which is also less than half the divided
charge. Being at 79 deg., it was a third time divided, and then fell to 36 deg.,
less than the half of 79 deg.. Such are the best results I could obtain; they
are not inconsistent with the belief that oil of turpentine has a greater
specific capacity than air, but they do not prove the fact, since the
disappearance of more than half the charge may be due to the conducting
power merely of the fluid.

1282. _Naphtha._--This liquid gave results similar in their nature and
direction to those with oil of turpentine.