tween respiration and fermentation, which is remarkably so in the
equality of heat produced in both in a healthy state of either, and
which seldom exceeds ninety-six degrees of Fahrenheit's thermometer;
but there are instances of their being much higher in both, without
producing much injury to either. Instances of this could be adduced at
home, without referring to warmer climates of the East and West Indies,
where the temperature of the atmosphere is so much higher than with us;
and that the temperature of the fermenting fluid, when at its height,
always exceeds that of the surrounding atmosphere in these latitudes,
which makes the similarity still stronger between these two decomposing
processes. This is a general and just remark; but, in order to regulate
it by practical facts, we must name the medium standard of heat, which
rarely exceeds eighty-five degrees with the brewers; this is the medium
of seventy-four and ninety-six degrees; but the medium heat is not
unfrequently up to ninety-six degrees in the distiller's fermenting
backs of Great Britain. Much depends on the degree of temperature the
fermentation is pitched at: here, nothing is spoken of but the
cleansing heat with the brewers, and the medium heat with the
distillers.

For the maintenance of combustion, the free access of air being
necessary, an objection may be raised to air-tight vats, as unfit to
carry on this process in, to the exclusion of external air; which
objection may seem to gather force from the compression it occasions of
the fixed air on the decomposing fluid, which is allowed to extinguish
active combustion. I must acknowledge these are formidable objections
to my definition of low combustion, but I by no means find them
unanswerable.

The aptitude of new hay, malt, and other vegetable matters, to
spontaneous combustion, when impacted together by incumbent pressure,
and a certain degree of moisture, should be recollected; and that this
tendency is not destroyed by excluding the admission of external air,
but by quickly cooling and dividing the impacted hay.

The great quantity of oxygen, or vital air, both in the water of
dilution, and in the fermentable matter, with which the fluid is more
or less saturated, should be also recollected, which is about
eighty-five parts in the former, and sixty-four parts of one hundred in
the latter.

Though, in an unelastic or fixed state, it is one of the properties of
combustion to disengage and r