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
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