pher, for which reason I shall enlarge
a little upon the subject in this place:

"Nature is at present in a state of equilibrium, which cannot have been
attained until all the spontaneous combustions or oxygenations possible
in an ordinary degree of temperature had taken place.... To illustrate
this abstract view of the matter by example: Let us suppose the usual
temperature of the earth a little changed, and it is raised only to the
degree of boiling water; it is evident that in this case phosphorus,
which is combustible in a considerably lower degree of temperature,
would no longer exist in nature in its pure and simple state, but would
always be procured in its acid or oxygenated state, and its radical
would become one of the substances unknown to chemistry. By gradually
increasing the temperature of the earth, the same circumstance would
successively happen to all the bodies capable of combustion; and, at
the last, every possible combustion having taken place, there would
no longer exist any combustible body whatever, and every substance
susceptible of the operation would be oxygenated and consequently
incombustible.

"There cannot, therefore, exist, as far as relates to us, any
combustible body but such as are non-combustible at the ordinary
temperature of the earth, or, what is the same thing in other words,
that it is essential to the nature of every combustible body not to
possess the property of combustion unless heated, or raised to a degree
of temperature at which its combustion naturally takes place. When this
degree is once produced, combustion commences, and the caloric which
is disengaged by the decomposition of the oxygen gas keeps up the
temperature which is necessary for continuing combustion. When this is
not the case--that is, when the disengaged caloric is not sufficient
for keeping up the necessary temperature--the combustion ceases. This
circumstance is expressed in the common language by saying that a body
burns ill or with difficulty."(10)

It needed the genius of such a man as Lavoisier to complete the
refutation of the false but firmly grounded phlogiston theory, and
against such a book as his Elements of Chemistry the feeble weapons of
the supporters of the phlogiston theory were hurled in vain.

But while chemists, as a class, had become converts to the new chemistry
before the end of the century, one man, Dr. Priestley, whose work had
done so much to found it, remained unconverted. In