conjecture, which I had thus formed, has been fully
confirmed by the accurate analysis of those waters. See vol. 3d. of the
Phil. Trans. of Edin.]

It may be, therefore, asserted, that no siliceous body having the
hardness of flint, nor any crystallization of that substance, has ever
been formed, except by fusion. If, by any art, this substance shall be
dissolved in simple water, or made to crystallise from any solution, in
that case, the assertion which has been here made may be denied.
But where there is not the vestige of any proof, to authorise the
supposition of flinty matter being dissolved by water, or crystallized
from that solution, such an hypothesis cannot be admitted, in opposition
to general and evident appearances[6].

[Note 6: The Chevalier de Dolomieu has imagined an ingenious theory for
the solution of siliceous substances in water [Journal de Physique, Mai
1792.]. This theory has not been taken up merely at a venture, but
is founded upon very accurate and interesting chemical experiments.
Hitherto, however, the nature of the siliceous substance is not
sufficiently known, to enable us to found, upon chemical principles, the
mineral operations of nature. That siliceous substance may be dissolved,
or rendered soluble in water, by means of alkaline salt, and that it may
be also volatilised by means of the fluor acid, is almost all that we
know upon the subject. But this is saying no more in relation to the
mineral operations employed upon the siliceous substance, than it would
be, in relation to those upon gold, to say that this metal is dissolved
by aqua regia.

It is to be admitted, that every simple substance may have its
menstruum, by means of which it may be retained with water in a
dissolved state; but from this it does not follow, that it is by the
means of aqueous solutions of all those mineral bodies, that nature
operates the consolidation of bodies, which we find actually
accomplished with all those different substances. It is the business of
this work to show, that from all appearances in the mineral regions, as
well as those upon the surface in the atmosphere, the supposition, of
that manner of consolidating bodies by solution, is inconsistent both
with natural appearances, and also with chemical principles.

Our ingenious author, who has, with, great diligence as well as an
enlightened mind, observed the operations of nature upon the surface
of the earth, here says, "ce n'est pas sans eto