the Temperature
of 55 deg., calculated from Everard's experiment, 511

ELEMENTS

OF

CHEMISTRY.

PART I.

Of the Formation and Decomposition of Aeriform Fluids--of the
Combustion of Simple Bodies--and the Formation of Acids.

CHAP. I.

_Of the Combinations of Caloric, and the Formation of Elastic Aeriform
Fluids._

That every body, whether solid or fluid, is augmented in all its
dimensions by any increase of its sensible heat, was long ago fully
established as a physical axiom, or universal proposition, by the
celebrated Boerhaave. Such facts as have been adduced for controverting
the generality of this principle offer only fallacious results, or, at
least, such as are so complicated with foreign circumstances as to
mislead the judgment: But, when we separately consider the effects, so
as to deduce each from the cause to which they separately belong, it is
easy to perceive that the separation of particles by heat is a constant
and general law of nature.

When we have heated a solid body to a certain degree, and have thereby
caused its particles to separate from each other, if we allow the body
to cool, its particles again approach each other in the same proportion
in which they were separated by the increased temperature; the body
returns through the same degrees of expansion which it before extended
through; and, if it be brought back to the same temperature from which
we set out at the commencement of the experiment, it recovers exactly
the same dimensions which it formerly occupied. But, as we are still
very far from being able to arrive at the degree of absolute cold, or
deprivation of all heat, being unacquainted with any degree of coldness
which we cannot suppose capable of still farther augmentation, it
follows, that we are still incapable of causing the ultimate particles
of bodies to approach each other as near as is possible; and,
consequently, that the particles of all bodies do not touch each other
in any state hitherto known, which, tho' a very singular conclusion, is
yet impossible to be denied.

It is supposed, that, since the particles of bodies are thus continually
impelled by heat to separate from each other, they would have no
connection between themselves; and, of consequence, that there could be
no solidity in nature, unless they were held together by some other
power which tends to unite them, and, so to speak, to chain them
together;