If this consolidating operation be performed at the bottom of the
ocean, or under great depths of the earth, of which our continents are
composed, we cannot be witnesses to this mineral process, or acquire the
knowledge of natural causes, by immediately observing the changes which
they produce; but though we have not this immediate observation of those
changes of bodies, we have, in science, the means of reasoning from
distant events; consequently, of discovering, in the general powers of
nature, causes for those events of which we see the effects.

That the consolidating operation, in general, lies out of the reach of
our immediate observation, will appear from the following truth: All the
consolidated masses, of which we now inquire into the cause, are, upon
the surface of the earth, in a state of general decay, although the
various natures of those bodies admit of that dissolution in very
different degrees[4]

From every view of the subject, therefore, we are directed to look into
those consolidated masses themselves, in order to find principles from
whence to judge of those operations by which they had attained their
hardness or consolidated state.

It must be evident, that nothing but the most general acquaintance with
the laws of acting substances, and with those of bodies changing by the
powers of nature, can enable us to set about this undertaking with any
reasonable prospect of success; and here the science of Chemistry must
be brought particularly to our aid; for this science, having for its
object the changes produced upon the sensible qualities, as they are
called, of bodies, by its means we may be enabled to judge of that which
is possible according to the laws of nature, and of that which, in like
manner, we must consider as impossible.