ny collateral operation, by which the nature of
that concretion might be ascertained in the same manner. In all
those cases, we see nothing but the concreted substances or their
crystallizations; but, no mark of any solvent or incrusting process is
to be perceived. On the contrary, almost all, or the greatest part
of them, are so situated, and attended with such circumstances, as
demonstrate the physical impossibility of that being the manner in which
they had been concreted; for, they are situated within close cavities,
through which nothing can pervade but heat, electricity, magnetism,
etc.; and they fill those cavities more or less, from the thinnest
incrustation of crystals to the full content of those cavities with
various substances, all regularly concreted or crystallised according to
an order which cannot apply to the concretion of any manner of solution.

That there is, in the mineral system, an operation of water which may
with great propriety be termed _infiltration_, I make no doubt. But this
operation of water, that may be employed in consolidating the strata
in the mineral regions, is essentially different from that which is
inconsiderately employed or supposed by mineralists when they talk
of infiltration; these two operations have nothing in common except
employing the water of the surface of the earth to percolate a porous
body. Now, the percolation of water may increase the porousness of that
body which it pervades, but never can thus change it from a porous to a
perfect solid body. But even the percolation of water through the strata
deposited at the bottom of the sea, necessarily required, according to
the supposition of naturalists, must be refused; for, the interstices of
those strata are, from the supposition of the case, already filled with
water; consequently, without first removing that stagnant water, it is
in vain to propose the infiltration of any fluid from the surface.

This is a difficulty which does not occur in our theory, where the
strata, deposited at the bottom of the sea, are to be afterwards heated
by the internal fires of the earth. The natural consequence of those
heating operations may be considered as the converting of the water
contained in the strata into steam, and the expulsion of steam or
vapour, by raising it up against the power of gravity, to be delivered
upon the surface of the earth and again condensed to the state of water.

Let us now conceive the strata, which had