st
powerfully, or at first, in the direction in which the dimensions of the
attenuated mass decrease, and then in the direction of the angles or
corners which from any cause may exist on the surface. This force not only
causes spontaneous diffusion of gases and other substances over the
surface, but is considered as very elementary in its nature, and competent
to account for all the phenomena of capillarity, chemical affinity,
attraction of aggregation, rarefaction, ebullition, volatilization,
explosion, and other thermometric effects, as well as inflammation,
detonation, &c. &c. It is considered as a form of heat to which the term
_native calorie_ is given, and is still further viewed as the principle of
the two electricities and the two magnetisms.

615. I have been the more anxious to give a correct abstract of Dr.
Fusinieri's view, both because I cannot form a distinct idea of the power
to which he refers the phenomena, and because of my imperfect knowledge of
the language in which the memoir is written. I would therefore beg to refer
those who pursue the subject to the memoir itself.

616. Not feeling, however, that the problem has yet been solved, I venture
to give the view which seems to me sufficient, upon _known principles_, to
account for the effect.

617. It may be observed of this action, that, with regard to platina, it
cannot be due to any peculiar, temporary condition, either of an electric
or of any other nature: the activity of plates rendered either positive or
negative by the pole, or cleaned with such different substances as acids,
alkalies, or water; charcoal, emery, ashes, or glass; or merely heated, is
sufficient to negative such an opinion. Neither does it depend upon the
spongy and porous, or upon the compact and burnished, or upon the massive
or the attenuated state of the metal, for in any of these states it may be
rendered effective, or its action may be taken away. The only essential
condition appears to be a _perfectly clean_ and _metallic surface_, for
whenever that is present the platina acts, whatever its form and condition
in other respects may be; and though variations in the latter points will
very much affect the rapidity, and therefore the visible appearances and
secondary effects, of the action, i.e. the ignition of the metal and the
inflammation of the gases, they, even in their most favourable state,
cannot produce any effect unless the condition of a clean, pure, metallic
surf