But whether this dissolution is performed by pure water, or by means
also of an acid, may perhaps be questioned. This, however, is certain,
that we must consider siliceous substances as insoluble in water.
The water of Glezer in Iceland undoubtedly contains this substance in
solution; but there is no reason to believe, that it is here dissolved
by any other than the natural means; that is, an alkaline substance, by
which siliceous bodies may be rendered soluble in water[5].
[Note 5: This 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].
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