I have already shown, Part I. Chap. IX. that oxygen does not always part
with the whole of the caloric it contained in the state of gas when it
enters into combination with other bodies. It carries almost the whole
of its caloric alongst with it in entering into the combinations which
form nitric acid and oxygenated muriatic acid; so that in nitrats, and
more especially in oxygenated muriats, the oxygen is, in a certain
degree, in the state of oxygen gas, condensed, and reduced to the
smallest volume it is capable of occupying.
In these combinations, the caloric exerts a constant action upon the
oxygen to bring it back to the state of gas; hence the oxygen adheres
but very slightly, and the smallest additional force is capable of
setting it free; and, when such force is applied, it often recovers the
state of gas instantaneously. This rapid passage from the solid to the
aeriform state is called detonation, or fulmination, because it is
usually accompanied with noise and explosion. Deflagrations are commonly
produced by means of combinations of charcoal either with nitre or
oxygenated muriat of potash; sometimes, to assist the inflammation,
sulphur is added; and, upon the just proportion of these ingredients,
and the proper manipulation of the mixture, depends the art of making
gun-powder.
As oxygen is changed, by deflagration with charcoal, into carbonic acid,
instead of oxygen gas, carbonic acid gas is disengaged, at least when
the mixture has been made in just proportions. In deflagration with
nitre, azotic gas is likewise disengaged, because azote is one of the
constituent elements of nitric acid.
The sudden and instantaneous disengagement and expansion of these gasses
is not, however, sufficient for explaining all the phenomena of
deflagration; because, if this were the sole operating power, gun powder
would always be so much the stronger in proportion as the quantity of
gas disengaged in a given time was the more considerable, which does not
always accord with experiment. I have tried some kinds which produced
almost double the effect of ordinary gun powder, although they gave out
a sixth part less of gas during deflagration. It would appear that the
quantity of caloric disengaged at the moment of detonation contributes
considerably to the expansive effects produced; for, although caloric
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