he
influence of metals, whilst others tend to _separate_, and that this
property varies in opposite directions with the different metals. At the
close of their second paper they observe, that the action is of a kind that
cannot be connected with any known theory; and though it is very remarkable
that the effects are transient, like those of most electrical actions, yet
they state that the greater number of the results observed by them are
inexplicable, by supposing them to be of a purely electric origin.

613. Dr. Fusinieri has also written on this subject, and given a theory
which he considers as sufficient to account for the phenomena[A]. He
expresses the immediate cause thus: "The platina determines upon its
surface a continual renovation of _concrete laminae_ of the combustible
substance of the gases or vapours, which flowing over it are burnt, pass
away, and are renewed: this combustion at the surface raises and sustains
the temperature of the metal." The combustible substance, thus reduced into
imperceptible laminae, of which the concrete parts are in contact with the
oxygen, is presumed to be in a state combinable with the oxygen at a much
lower temperature than when it is in the gaseous state, and more in analogy
with what is called the nascent condition. That combustible gases should
lose their elastic state, and become concrete, assuming the form of
exceedingly attenuated but solid strata, is considered as proved by facts,
some of which are quoted in the Giornale di Fisica for 1824[B]; and though
the theory requires that they should assume this state at high
temperatures, and though the _similar_ films of aqueous and other matter
are dissipated by the action of heat, still the facts are considered as
justifying the conclusion against all opposition of reasoning.

[A] Giornale di Fisica, &c., 1825, tom. viii. p. 259.

[B] pp. 138, 371.

614. The power or force which makes combustible gas or vapour abandon its
elastic state in contact with a solid, that it may cover the latter with a
thin stratum of its own proper substance, is considered as being neither
attraction nor affinity. It is able also to extend liquids and solids in
concrete laminae over the surface of the acting solid body, and consists in
a _repulsion_, which is developed from the parts of the solid body by the
simple fact of attenuation, and is highest when the attenuation is most
complete. The force has a progressive development, and acts mo