produced by that very evaporation
itself; for as, in proportion to the increase of elastic fluids, the
pressure of the atmosphere would be augmented, as every degree of
pressure tends, in some measure, to prevent evaporation, and as even the
most evaporable fluids can resist the operation of a very high
temperature without evaporating, if prevented by a proportionally
stronger compression, water and all other liquids being able to sustain
a red heat in Papin's digester; we must admit, that the new atmosphere
would at last arrive at such a degree of weight, that the water which
had not hitherto evaporated would cease to boil, and, of consequence,
would remain liquid; so that, even upon this supposition, as in all
others of the same nature, the increasing gravity of the atmosphere
would find certain limits which it could not exceed. We might even
extend these reflections greatly farther, and examine what change might
be produced in such situations upon stones, salts, and the greater part
of the fusible substances which compose the mass of our earth. These
would be softened, fused, and changed into fluids, &c.: But these
speculations carry me from my object, to which I hasten to return.

By a contrary supposition to the one we have been forming, if the earth
were suddenly transported into a very cold region, the water which at
present composes our seas, rivers, and springs, and probably the greater
number of the fluids we are acquainted with, would be converted into
solid mountains and hard rocks, at first diaphanous and homogeneous,
like rock crystal, but which, in time, becoming mixed with foreign and
heterogeneous substances, would become opake stones of various colours.
In this case, the air, or at least some part of the aeriform fluids
which now compose the mass of our atmosphere, would doubtless lose its
elasticity for want of a sufficient temperature to retain them in that
state: They would return to the liquid state of existence, and new
liquids would be formed, of whose properties we cannot, at present, form
the most distant idea.

These two opposite suppositions give a distinct proof of the following
corollaries: _First_, That _solidity_, _liquidity_, and _aeriform
elasticity_, are only three different states of existence of the same
matter, or three particular modifications which almost all substances
are susceptible of assuming successively, and which solely depend upon
the degree of temperature to which they