many at once.
We may make these different channels of different bodies, and by
proportioning their thicknesses and lengths, may include such substances as
air, lac, spermaceti, water, protoxide of iron, iron and silver, and by
_one_ discharge make each convey its proportion of the electric force.
Perhaps the air ought to be excepted, as its discharge by conduction is
questionable at present (1336.); but the others may all be limited in their
mode of discharge to pure conduction. Yet several of them suffer previous
induction, precisely like the induction through the air, it being a
necessary preliminary to their discharging action. How can we therefore
separate any one of these bodies from the others, as to the _principles and
mode_ of insulating and conducting, except by mere degree? All seem to me
to be dielectrics acting alike, and under the same common laws.

[A] _Philosophical Transactions_, 1776, p. 197.

1335. I might draw another argument in favour of the general sameness, in
nature and action, of good and bad conductors (and all the bodies I refer
to are conductors more or less), from the perfect equipoise in action of
very different bodies when opposed to each other in magneto-electric
inductive action, as formerly described (213.), but am anxious to be as
brief as is consistent with the clear examination of the probable truth of
my views.

1336. With regard to the possession by the gases of any conducting power
of the simple kind now under consideration, the question is a very
difficult one to determine at present. Experiments seem to indicate that
they do insulate certain low degrees of tension perfectly, and that the
effects which may have appeared to be occasioned by _conduction_ have been
the result of the carrying power of the charged particles, either of the
air or of dust, in it. It is equally certain, however, that with higher
degrees of tension or charge the particles discharge to one another, and
that is conduction. If the gases possess the power of insulating a certain
low degree of tension continuously and perfectly, such a result may be due
to their peculiar physical state, and the condition of separation under
which their particles are placed. But in that, or in any case, we must not
forget the fine experiments of Cagniard de la Tour[A], in which he has
shown that liquids and their vapours can be made to pass gradually into
each other, to the entire removal of any marked distinction of the tw