o
states. Thus, hot dry steam and cold water pass by insensible gradations
into each other; yet the one is amongst the gases as an insulator, and the
other a comparatively good conductor. As to conducting power, therefore,
the transition from metals even up to gases is gradual; substances make but
one series in this respect, and the various cases must come under one
condition and law (444.). The specific differences of bodies as to
conducting power only serves to strengthen the general argument, that
conduction, like insulation, is a result of induction, and is an action of
contiguous particles.

[A] Annales de Chimie, xxi. pp. 127, 178, or Quarterly Journal of
Science, xv. 145.

1337. I might go on now to consider induction and its concomitant,
_conduction_, through mixed dielectrics, as, for instance, when a charged
body, instead of acting across air to a distant uninsulated conductor, acts
jointly through it and an interposed insulated conductor. In such a case,
the air and the conducting body are the mixed dielectrics; and the latter
assumes a polarized condition as a mass, like that which my theory assumes
_each particle_ of the air to possess at the same time (1679). But I fear
to be tedious in the present condition of the subject, and hasten to the
consideration of other matter.

1338. To sum up, in some degree, what has been said, I look upon the first
effect of an excited body upon neighbouring matters to be the production of
a polarized state of their particles, which constitutes _induction_; and
this arises from its action upon the particles in immediate contact with
it, which again act upon those contiguous to them, and thus the forces are
transferred to a distance. If the induction remain undiminished, then
perfect insulation is the consequence; and the higher the polarized
condition which the particles can acquire or maintain, the higher is the
intensity which may be given to the acting forces. If, on the contrary, the
contiguous particles, upon acquiring the polarized state, have the power to
communicate their forces, then conduction occurs, and the tension is
lowered, conduction being a distinct act of discharge between neighbouring
particles. The lower the state of tension at which this discharge between
the particles of a body takes place, the better conductor is that body. In
this view, insulators may be said to be bodies whose particles can retain
the polarized state; whilst conductors are thos