Of Gunpowder &c
Gunpowder being a principal ingredient in fire-works, it will not be
improper to give a short definition of its strange explosive force,
and cause of action, which, according to Dr. Shaw's opinion of the
chemical cause of the explosive force of gunpowder, is as
follows:--"Each grain of gunpowder consisting of a certain proportion
of sulphur, nitre, and coal, the coal presently taking fire, upon
contact of the smallest
park; at which time both the sulphur and the
nitre immediately melt, and by means of the coal interposed between
them, burst into flame; which spreading from grain to grain,
propagates the same effect almost instantaneously, whence the whole
mass of powder comes to be fired; and as nitre contains a large
proportion both of air and water, which are now violently rarefied by
the heat, a kind of fiery explosive blast is thus produced, wherein
the nitre seems, by its aqueous and aerial parts, to act as bellows to
the other inflammable bodies (sulphur and coal) to blow them into a
flame, and carry off their whole substance in smoke and vapour."